Genome-wide transcriptomic analysis of the effects of sub-ambient atmospheric oxygen and elevated atmospheric carbon dioxide levels on gametophytes of the moss, Physcomitrella patens

PubMed Central

Shinde, Suhas; Behpouri, Ali; McElwain, Jennifer C.; Ng, Carl K.-Y.

2015-01-01

It is widely accepted that atmospheric O2 has played a key role in the development of life on Earth, as evident from the coincidence between the rise of atmospheric O2 concentrations in the Precambrian and biological evolution. Additionally, it has also been suggested that low atmospheric O2 is one of the major drivers for at least two of the five mass-extinction events in the Phanerozoic. At the molecular level, our understanding of the responses of plants to sub-ambient O2 concentrations is largely confined to studies of the responses of underground organs, e.g. roots to hypoxic conditions. Oxygen deprivation often results in elevated CO2 levels, particularly under waterlogged conditions, due to slower gas diffusion in water compared to air. In this study, changes in the transcriptome of gametophytes of the moss Physcomitrella patens arising from exposure to sub-ambient O2 of 13% (oxygen deprivation) and elevated CO2 (1500 ppmV) were examined to further our understanding of the responses of lower plants to changes in atmospheric gaseous composition. Microarray analyses revealed that the expression of a large number of genes was affected under elevated CO2 (814 genes) and sub-ambient O2 conditions (576 genes). Intriguingly, the expression of comparatively fewer numbers of genes (411 genes) was affected under a combination of both sub-ambient O2 and elevated CO2 condition (low O2–high CO2). Overall, the results point towards the effects of atmospheric changes in CO2 and O2 on transcriptional reprogramming, photosynthetic regulation, carbon metabolism, and stress responses. PMID:25948702

Genome-wide transcriptomic analysis of the effects of sub-ambient atmospheric oxygen and elevated atmospheric carbon dioxide levels on gametophytes of the moss, Physcomitrella patens.

PubMed

Shinde, Suhas; Behpouri, Ali; McElwain, Jennifer C; Ng, Carl K-Y

2015-07-01

It is widely accepted that atmospheric O2 has played a key role in the development of life on Earth, as evident from the coincidence between the rise of atmospheric O2 concentrations in the Precambrian and biological evolution. Additionally, it has also been suggested that low atmospheric O2 is one of the major drivers for at least two of the five mass-extinction events in the Phanerozoic. At the molecular level, our understanding of the responses of plants to sub-ambient O2 concentrations is largely confined to studies of the responses of underground organs, e.g. roots to hypoxic conditions. Oxygen deprivation often results in elevated CO2 levels, particularly under waterlogged conditions, due to slower gas diffusion in water compared to air. In this study, changes in the transcriptome of gametophytes of the moss Physcomitrella patens arising from exposure to sub-ambient O2 of 13% (oxygen deprivation) and elevated CO2 (1500 ppmV) were examined to further our understanding of the responses of lower plants to changes in atmospheric gaseous composition. Microarray analyses revealed that the expression of a large number of genes was affected under elevated CO2 (814 genes) and sub-ambient O2 conditions (576 genes). Intriguingly, the expression of comparatively fewer numbers of genes (411 genes) was affected under a combination of both sub-ambient O2 and elevated CO2 condition (low O2-high CO2). Overall, the results point towards the effects of atmospheric changes in CO2 and O2 on transcriptional reprogramming, photosynthetic regulation, carbon metabolism, and stress responses. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Evaluation of three automatic oxygen therapy control algorithms on ventilated low birth weight neonates.

PubMed

Morozoff, Edmund P; Smyth, John A

2009-01-01

Neonates with under developed lungs often require oxygen therapy. During the course of oxygen therapy, elevated levels of blood oxygenation, hyperoxemia, must be avoided or the risk of chronic lung disease or retinal damage is increased. Low levels of blood oxygen, hypoxemia, may lead to permanent brain tissue damage and, in some cases, mortality. A closed loop controller that automatically administers oxygen therapy using 3 algorithms - state machine, adaptive model, and proportional integral derivative (PID) - is applied to 7 ventilated low birth weight neonates and compared to manual oxygen therapy. All 3 automatic control algorithms demonstrated their ability to improve manual oxygen therapy by increasing periods of normoxemia and reducing the need for manual FiO(2) adjustments. Of the three control algorithms, the adaptive model showed the best performance with 0.25 manual adjustments per hour and 73% time spent within target +/- 3% SpO(2).

Evaluation of reactive oxygen metabolites in patients with non-small cell lung cancer after chemotherapy

PubMed Central

2014-01-01

Background The aim of this study was to evaluate the level of reactive oxygen metabolites (ROMs) after chemotherapy in patients with non-small cell lung cancer (NSCLC) and its association with response to treatment. Methods Fifty-eight untreated NSCLC patients and twenty-three healthy subjects were selected for the study. Patients received two courses of platinum-based chemotherapy and were evaluated for oxidative stress and treatment response. As a marker of reactive oxygen species, ROMs levels were measured using the d-ROMs test. Results ROMs level (mean ± standard deviation) before chemotherapy in NSCLC patients (416 ± 135 U.CARR) was significantly elevated (p = 0.016) compared to normal healthy subjects (320 ± 59 U.CARR). Patients who responded to chemotherapy showed significantly decreased (p = 0.014) ROMs levels after chemotherapy, whereas patients who had stable disease or progressive disease showed no change in ROMs level (p = 0.387). Conclusions NSCLC patients had significantly elevated ROMs levels before chemotherapy compared with normal healthy subjects. Chemotherapy may suppress ROMs production in responders but not in non-responders. ROMs level may be a predictor of clinical outcome in patients receiving chemotherapy for NSCLC. PMID:25180083

Lung and Diaphragm Damage at Varying Oxygen Levels and Ventilator Modes Pst Hemorrhagic

DTIC Science & Technology

2011-12-20

scavenging in prenatal neonates (Vento et al., 2009). In addition, Lee et al. found that mice breathing 40% oxygen had elevated tissue levels of...pulmonary mechanics. Another limitation was that we did not administer any fluid resuscitation to correct the hemorrhagic shock during mechanical... resuscitation . Testing only a controlled mode of mechanical ventilation was a limitation to our study. Most mechanical ventilations offer a mixed mode of

Low Oxygen Tension Enhances Hepatitis C Virus Replication

PubMed Central

Kalliampakou, K. I.; Kotta-Loizou, I.; Befani, C.; Liakos, P.; Simos, G.; Mentis, A. F.; Kalliaropoulos, A.; Doumba, P. P.; Smirlis, D.; Foka, P.; Bauhofer, O.; Poenisch, M.; Windisch, M. P.; Lee, M. E.; Koskinas, J.; Bartenschlager, R.

2013-01-01

Low oxygen tension exerts a significant effect on the replication of several DNA and RNA viruses in cultured cells. In vitro propagation of hepatitis C virus (HCV) has thus far been studied under atmospheric oxygen levels despite the fact that the liver tissue microenvironment is hypoxic. In this study, we investigated the efficiency of HCV production in actively dividing or differentiating human hepatoma cells cultured under low or atmospheric oxygen tensions. By using both HCV replicons and infection-based assays, low oxygen was found to enhance HCV RNA replication whereas virus entry and RNA translation were not affected. Hypoxia signaling pathway-focused DNA microarray and real-time quantitative reverse transcription-PCR (qRT-PCR) analyses revealed an upregulation of genes related to hypoxic stress, glycolytic metabolism, cell growth, and proliferation when cells were kept under low (3% [vol/vol]) oxygen tension, likely reflecting cell adaptation to anaerobic conditions. Interestingly, hypoxia-mediated enhancement of HCV replication correlated directly with the increase in anaerobic glycolysis and creatine kinase B (CKB) activity that leads to elevated ATP production. Surprisingly, activation of hypoxia-inducible factor alpha (HIF-α) was not involved in the elevation of HCV replication. Instead, a number of oncogenes known to be associated with glycolysis were upregulated and evidence that these oncogenes contribute to hypoxia-mediated enhancement of HCV replication was obtained. Finally, in liver biopsy specimens of HCV-infected patients, the levels of hypoxia and anaerobic metabolism markers correlated with HCV RNA levels. These results provide new insights into the impact of oxygen tension on the intricate HCV-host cell interaction. PMID:23269812

Storage Capacity and Water Quality of Lake Ngardok, Babeldaob Island, Republic of Palau, 1996-98

USGS Publications Warehouse

Yeung, Chiu Wang; Wong, Michael F.

1999-01-01

A bathymetric survey conducted during March and April, 1996, determined the total storage capacity Lake Ngardok to be between 90 and 168 acre-feet. Elevation-surface area and elevation-capacity curves summarizing the current relations among elevation, surface area, and storage capacity were created from the bathymetric map. Rainfall and lake-elevation data collected from April 1996 to March 1998 indicated that lake levels correlated to rainfall values with lake elevation rising rapidly in response to heavy rainfall and then returning to normal levels within a few days. Mean lake elevation for the 22 month period of data was 59.5 feet which gives a mean storage capacity of 107 acre-feet and a mean surface area of 24.1 acre. A floating mat of reeds, which covered 58 percent of the lake surface area at the time of the bathymetric survey, makes true storage capacity difficult to estimate. Water-quality sampling during April 1996 and November 1997 indicated that no U.S. Environmental Protection Agency primary drinking-water standards were violated for analyzed organic and inorganic compounds and radionuclides. With suitable biological treatment, the lake water could be used for drinking-water purposes. Temperature and dissolved oxygen measurements indicated that Lake Ngardok is stratified. Given that air temperature on Palau exhibits little seasonal variation, it is likely that this pattern of stratification is persistent. As a result, complete mixing of the lake is probably rare. Near anaerobic conditions exist at the lake bottom. Low dissolved oxygen (3.2 milligrams per liter) measured at the outflow indicated that water flowing past the outflow was from the deep oxygen-depleted depths of the lake.

Muscle Microvascular Blood Flow, Oxygenation, pH, and Perfusion Pressure Decrease in Simulated Acute Compartment Syndrome.

PubMed

Challa, Sravya T; Hargens, Alan R; Uzosike, Amarachi; Macias, Brandon R

2017-09-06

The current gold standard for diagnosing acute compartment syndrome (ACS) is an assessment of clinical signs, invasive measurement of intramuscular pressure (IMP), and measurement of local perfusion pressure. However, IMP measurements have several shortcomings, including pain, risk of infection, risk of technique error, plugging of the catheter tip, lack of consensus on the diagnostic pressure threshold, and lack of specificity and sensitivity. The objective of this study was to evaluate muscle hemodynamics, oxygenation, and pH as diagnostic parameters in a human model of ACS. We hypothesized that as IMP increases, muscle microvascular blood flow, oxygenation, and pH decrease in the anterior compartment of a leg at heart level and that they decrease significantly more when the leg is elevated further. An external pneumatic leg pressure chamber, combined with a venous stasis thigh cuff, was used to increase IMP and simulate ACS. Eight healthy subjects (5 males and 3 females; mean age, 26 years) had photoplethysmography and near-infrared spectroscopy-pH sensors placed over the middle aspect of the tibialis anterior muscle of the right (experimental) and left (control) legs. Leg chamber pressure conditions (40, 50, and 60 mm Hg) were applied in a randomized order after baseline measurements were taken. Data were collected continuously for each 11-minute pressure condition, with an 11-minute recovery period after each condition, and the average of the last 6 minutes was used for data analyses. The same protocol was repeated with each subject's legs elevated 12 cm above heart level. Data were analyzed using repeated-measures analysis of variance (ANOVA). As IMP increased, muscle microvascular blood flow (p = 0.01), oxygenation (p < 0.001), and pH (p < 0.001) all decreased significantly in the experimental leg compared with the control leg. At all IMP levels, leg elevation significantly decreased muscle oxygenation (p = 0.013) and perfusion pressure (p = 0.03) compared with the control leg at heart level. These results indicate that muscle microvascular blood flow, oxygenation, pH, and perfusion pressure decrease significantly as IMP increases in a human model of ACS. This study identifies hemodynamic and metabolic parameters as potential noninvasive diagnostic tools for ACS.

Aerobic scope fails to explain the detrimental effects on growth resulting from warming and elevated CO2 in Atlantic halibut.

PubMed

Gräns, Albin; Jutfelt, Fredrik; Sandblom, Erik; Jönsson, Elisabeth; Wiklander, Kerstin; Seth, Henrik; Olsson, Catharina; Dupont, Sam; Ortega-Martinez, Olga; Einarsdottir, Ingibjörg; Björnsson, Björn Thrandur; Sundell, Kristina; Axelsson, Michael

2014-03-01

As a consequence of increasing atmospheric CO2, the world's oceans are becoming warmer and more acidic. Whilst the ecological effects of these changes are poorly understood, it has been suggested that fish performance including growth will be reduced mainly as a result of limitations in oxygen transport capacity. Contrary to the predictions given by the oxygen- and capacity-limited thermal tolerance hypothesis, we show that aerobic scope and cardiac performance of Atlantic halibut (Hippoglossus hippoglossus) increase following 14-16 weeks exposure to elevated temperatures and even more so in combination with CO2-acidified seawater. However, the increase does not translate into improved growth, demonstrating that oxygen uptake is not the limiting factor for growth performance at high temperatures. Instead, long-term exposure to CO2-acidified seawater reduces growth at temperatures that are frequently encountered by this species in nature, indicating that elevated atmospheric CO2 levels may have serious implications on fish populations in the future.

Differential signal pathway activation and 5-HT function: the role of gut enterochromaffin cells as oxygen sensors.

PubMed

Haugen, Martin; Dammen, Rikard; Svejda, Bernhard; Gustafsson, Bjorn I; Pfragner, Roswitha; Modlin, Irvin; Kidd, Mark

2012-11-15

The chemomechanosensory function of the gut enterochromaffin (EC) cell enables it to respond to dietary agents and mechanical stretch. We hypothesized that the EC cell, which also sensed alterations in luminal or mucosal oxygen level, was physiologically sensitive to fluctuations in O(2). Given that low oxygen levels induce 5-HT production and secretion through a hypoxia inducible factor 1α (HIF-1α)-dependent pathway, we also hypothesized that increasing O(2) would reduce 5-HT production and secretion. Isolated normal EC cells as well as the well-characterized EC cell model KRJ-I were used to examine HIF signaling (luciferase-assays), hypoxia transcriptional response element (HRE)-mediated transcription (PCR), signaling pathways (Western blot), and 5-HT release (ELISA) during exposure to different oxygen levels. Normal EC cells and KRJ-I cells express HIF-1α, and transient transfection with Renilla luciferase under HRE control identified a hypoxia-mediated pathway in these cells. PCR confirmed activation of HIF-downstream targets, GLUT1, IGF2, and VEGF under reduced O(2) levels (0.5%). Reducing O(2) also elevated 5-HT secretion (2-3.2-fold) as well as protein levels of HIF-1α (1.7-3-fold). Increasing O(2) to 100% inhibited HRE-mediated signaling, transcription, reduced 5-HT secretion, and significantly lowered HIF-1α levels (∼75% of control). NF-κB signaling was also elevated during hypoxia (1.2-1.6-fold), but no significant changes were noted in PKA/cAMP. We concluded that gut EC cells are oxygen responsive, and alterations in O(2) levels differentially activate HIF-1α and tryptophan hydroxylase 1, as well as NF-κB signaling. This results in alterations in 5-HT production and secretion and identifies that the chemomechanosensory role of EC cells extends to oxygen sensing.

Changes in plasma phenylalanine, isoleucine, leucine, and valine are associated with significant changes in intracranial pressure and jugular venous oxygen saturation in patients with severe traumatic brain injury.

PubMed

Vuille-Dit-Bille, Raphael N; Ha-Huy, Riem; Stover, John F

2012-09-01

Changes in plasma aromatic amino acids (AAA = phenylalanine, tryptophan, tyrosine) and branched chain amino acids (BCAA = isoleucine, leucine, valine) levels possibly influencing intracranial pressure (ICP) and cerebral oxygen consumption (SjvO(2)) were investigated in 19 sedated patients up to 14 days following severe traumatic brain injury (TBI). Compared to 44 healthy volunteers, jugular venous plasma BCAA were significantly decreased by 35% (p < 0.001) while AAA were markedly increased in TBI patients by 19% (p < 0.001). The BCAA to AAA ratio was significantly decreased by 55% (p < 0.001) which persisted during the entire study period. Elevated plasma phenylalanine was associated with decreased ICP and increased SjvO(2), while higher plasma isoleucine and leucine levels were associated with increased ICP and higher plasma leucine and valine were linked to decreased SjvO(2). The amount of enterally administered amino acids was associated with significantly increased plasma levels with the exception of phenylalanine. Contrary to the initial assumption that elevated AAA and decreased BCAA levels are detrimental, increased plasma phenylalanine levels were associated with beneficial signs in terms of decreased ICP and reduced cerebral oxygen consumption reflected by increased SjvO(2); concomitantly, elevated plasma isoleucine and leucine levels were associated with increased ICP while leucine and valine were associated with decreased SjvO(2) following severe TBI, respectively. The impact of enteral nutrition on this observed pattern must be examined prospectively to determine if higher amounts of phenylalanine should be administered to promote beneficial effects on brain metabolism and if normalization of plasma BCAA levels is without cerebral side effects.

Oxygenation level and hemoglobin concentration in experimental tumor estimated by diffuse optical spectroscopy

NASA Astrophysics Data System (ADS)

Orlova, A. G.; Kirillin, M. Yu.; Volovetsky, A. B.; Shilyagina, N. Yu.; Sergeeva, E. A.; Golubiatnikov, G. Yu.; Turchin, I. V.

2017-07-01

Using diffuse optical spectroscopy the level of oxygenation and hemoglobin concentration in experimental tumor in comparison with normal muscle tissue of mice have been studied. Subcutaneously growing SKBR-3 was used as a tumor model. Continuous wave fiber probe diffuse optical spectroscopy system was employed. Optical properties extraction approach was based on diffusion approximation. Decreased blood oxygen saturation level and increased total hemoglobin content were demonstrated in the neoplasm. The main reason of such differences between tumor and norm was significant elevation of deoxyhemoglobin concentration in SKBR-3. The method can be useful for diagnosis of tumors as well as for study of blood flow parameters of tumor models with different angiogenic properties.

Sustained Radiosensitization of Hypoxic Glioma Cells after Oxygen Pretreatment in an Animal Model of Glioblastoma and In Vitro Models of Tumor Hypoxia

PubMed Central

Clarke, Ryon H.; Moosa, Shayan; Anzivino, Matthew; Wang, Yi; Floyd, Desiree Hunt; Purow, Benjamin W.; Lee, Kevin S.

2014-01-01

Glioblastoma multiforme (GBM) is the most common and lethal form of brain cancer and these tumors are highly resistant to chemo- and radiotherapy. Radioresistance is thought to result from a paucity of molecular oxygen in hypoxic tumor regions, resulting in reduced DNA damage and enhanced cellular defense mechanisms. Efforts to counteract tumor hypoxia during radiotherapy are limited by an attendant increase in the sensitivity of healthy brain tissue to radiation. However, the presence of heightened levels of molecular oxygen during radiotherapy, while conventionally deemed critical for adjuvant oxygen therapy to sensitize hypoxic tumor tissue, might not actually be necessary. We evaluated the concept that pre-treating tumor tissue by transiently elevating tissue oxygenation prior to radiation exposure could increase the efficacy of radiotherapy, even when radiotherapy is administered after the return of tumor tissue oxygen to hypoxic baseline levels. Using nude mice bearing intracranial U87-luciferase xenografts, and in vitro models of tumor hypoxia, the efficacy of oxygen pretreatment for producing radiosensitization was tested. Oxygen-induced radiosensitization of tumor tissue was observed in GBM xenografts, as seen by suppression of tumor growth and increased survival. Additionally, rodent and human glioma cells, and human glioma stem cells, exhibited prolonged enhanced vulnerability to radiation after oxygen pretreatment in vitro, even when radiation was delivered under hypoxic conditions. Over-expression of HIF-1α reduced this radiosensitization, indicating that this effect is mediated, in part, via a change in HIF-1-dependent mechanisms. Importantly, an identical duration of transient hyperoxic exposure does not sensitize normal human astrocytes to radiation in vitro. Taken together, these results indicate that briefly pre-treating tumors with elevated levels of oxygen prior to radiotherapy may represent a means for selectively targeting radiation-resistant hypoxic cancer cells, and could serve as a safe and effective adjuvant to radiation therapy for patients with GBM. PMID:25350400

A benzoxazine derivative induces vascular endothelial cell apoptosis in the presence of fibroblast growth factor-2 by elevating NADPH oxidase activity and reactive oxygen species levels.

PubMed

Zhao, Jing; He, Qiuxia; Cheng, Yizhe; Zhao, Baoxiang; Zhang, Yun; Zhang, Shangli; Miao, Junying

2009-09-01

Previously, we found that 6,8-dichloro-2,3-dihydro-3-hydroxymethyl-1,4-benzoxazine (DBO) promoted apoptosis of human umbilical vascular endothelial cells (HUVECs) deprived of growth factors. In this study, we aimed to investigate the effect of DBO and its mechanism of action on angiogenesis and apoptosis of HUVECs in the presence of fibroblast growth factor-2 (FGF-2), which promotes angiogenesis and inhibits apoptosis in vivo and in vitro. DBO significantly inhibited capillary-like tube formation by promoting apoptosis of HUVECs in the presence of FGF-2 in vitro. Furthermore, DBO elevated the levels of reactive oxygen species (ROS) and nitric oxide (NO) and increased the activity of NADPH oxidase and inducible nitric oxide synthase (iNOS) in promoting apoptosis under this condition. Moreover, when NADPH oxidase was inhibited by its specific inhibitor, dibenziodolium chloride (DPI), DBO could not elevate ROS and NO levels in HUVECs. The data suggest that DBO is a new modulator of apoptosis in vitro, and it might function by increasing the activity of NADPH oxidase and iNOS, subsequently elevating the levels of ROS and NO in HUVECs. The findings of this study provide a new small molecule for investigating the FGF-2/NADPH oxidase/iNOS signaling pathway in apoptosis.

Results of a preimpoundment water-quality study of Swatara Creek, Pennsylvania

USGS Publications Warehouse

Fishel, David K.; Richardson, J.E.

1986-01-01

The impoundment will act as a sediment trap and thus reduce the concentrations of total phosphorus, iron, aluminum, lead, copper, and zinc immediately downstream from the impoundment. Large storm discharges and releases from the hypolimnion of the reservoir to attain the winter-pool level may contain low oxygen concentrations and elevated concentrations of iron, aluminum, lead, copper, and zinc. Unless conservation releases from the multi-level release gates are carefully controlled, low dissolved-oxygen levels and high metal concentrations may degrade the downstream water quality and be detrimental to the aquatic community.

Serum Aminotransferase Levels are Associated with Markers of Hypoxia in Patients with Obstructive Sleep Apnea

PubMed Central

Norman, Daniel; Bardwell, Wayne A.; Arosemena, Farah; Nelesen, Richard; Mills, Paul J.; Loredo, Jose S.; Lavine, Joel E.; Dimsdale, Joel E.

2008-01-01

Study Objectives: Nonalcoholic fatty liver disease (NAFLD) is a disorder that often presents with elevated serum aminotransferase levels. Although it has classically been linked with the metabolic syndrome, recent studies suggest NAFLD may also be associated with obstructive sleep apnea (OSA). This study evaluates the association between serum aminotransferase levels and factors connected with: either the metabolic syndrome (elevated body mass index [BMI], lipid profile, blood pressure, fasting glucose), or with OSA severity (apnea hypopnea index, lowest oxygen saturation level, oxygen desaturation index, percent of time below 90% saturation [%T<90]). Design: Retrospective case series. Patients and Setting: 109 adult patients with OSA at a university hospital general clinical research center. Measurements and Results: Markers of hypoxia (lowest oxygen saturation level and %T<90), correlated significantly with aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels (Pearson's r = −0.31 to −0.38, P <0.003), while apnea hypopnea index, body mass index, blood pressure, fasting glucose, triglyceride, and cholesterol levels did not. Hierarchical linear regression was then done to determine the best predictors of aminotransferase levels. Markers of metabolic syndrome were entered as one block and markers of sleep apnea as another. Regression analyses explained 16.3% of the variance in AST and 18.9% of the variance in ALT, with %T<90 playing the largest role. Conclusions: In patients with obstructive sleep apnea, serum aminotransferase levels are better predicted by markers of oxygen desaturation than by factors traditionally associated with the metabolic syndrome. Citation: Norman D; Bardwell WA; Arosemena F; Nelesen R; Mills PJ; Loredo JS; Lavine JE; Dimsdale JE. Serum aminotransferase levels are associated with markers of hypoxia in patients with obstructive sleep apnea. SLEEP 2008;31(1):-121-126. PMID:18220085

Preservation of high glycolytic phenotype by establishing new acute lymphoblastic leukemia cell lines at physiologic oxygen concentration.

PubMed

Sheard, Michael A; Ghent, Matthew V; Cabral, Daniel J; Lee, Joanne C; Khankaldyyan, Vazgen; Ji, Lingyun; Wu, Samuel Q; Kang, Min H; Sposto, Richard; Asgharzadeh, Shahab; Reynolds, C Patrick

2015-05-15

Cancer cells typically exhibit increased glycolysis and decreased mitochondrial oxidative phosphorylation, and they continue to exhibit some elevation in glycolysis even under aerobic conditions. However, it is unclear whether cancer cell lines employ a high level of glycolysis comparable to that of the original cancers from which they were derived, even if their culture conditions are changed to physiologically relevant oxygen concentrations. From three childhood acute lymphoblastic leukemia (ALL) patients we established three new pairs of cell lines in both atmospheric (20%) and physiologic (bone marrow level, 5%) oxygen concentrations. Cell lines established in 20% oxygen exhibited lower proliferation, survival, expression of glycolysis genes, glucose consumption, and lactate production. Interestingly, the effects of oxygen concentration used during cell line initiation were only partially reversible when established cell cultures were switched from one oxygen concentration to another for eight weeks. These observations indicate that ALL cell lines established at atmospheric oxygen concentration can exhibit relatively low levels of glycolysis and these levels are semi-permanent, suggesting that physiologic oxygen concentrations may be needed from the time of cell line initiation to preserve the high level of glycolysis commonly exhibited by leukemias in vivo. Copyright © 2015. Published by Elsevier Inc.

Fluctuations in oxygen influence facultative endothermy in bumblebees.

PubMed

Dzialowski, Edward M; Tattersall, Glenn J; Nicol, Stewart C; Frappell, Peter B

2014-11-01

Bumblebees are facultative endotherms, having the ability to elevate thorax temperature above ambient temperature by elevating metabolism. Here, we investigated the influence of hypoxia on metabolic demands and thermoregulatory capabilities of the bumblebee Bombus terrestris. We measured thorax temperature, rates of oxygen consumption and carbon dioxide production, and abdominal pumping rates of bees randomly exposed to oxygen levels of 20, 15, 10 and 5 kPa at 26°C. Under normoxia, bumblebees maintained an elevated mean thorax temperature of 35.5°C. There was no significant change in thorax temperature at 15 kPa O2 (33.4°C). Mean thorax temperature decreased significantly at 10 kPa O2 (31.6°C) and 5 kPa O2 (27.3°C). Bees were able to maintain an elevated metabolic rate at 15 and 10 kPa O2. In normoxia, endothermic bees exhibited periods of rapid abdominal pumping (327 min(-1)) interspaced by periods of no abdominal pumping. At 10 kPa O2, abdominal pumping rate decreased (255 min(-1)) but became more continuous. Upon exposure to 5 kPa, metabolic rate and abdominal pumping rate (152 min(-1)) decreased, although the animals continued abdominal pumping at the reduced rate throughout the exposure period. Bumblebees are able to meet the energetic demands of endothermy at 15 kPa O2, but become compromised at levels of 10 kPa O2 and below. © 2014. Published by The Company of Biologists Ltd.

Effects of oxygen on responses to heating in two lizard species sampled along an elevational gradient.

PubMed

DuBois, P Mason; Shea, Tanner K; Claunch, Natalie M; Taylor, Emily N

2017-08-01

Thermal tolerance is an important variable in predictive models about the effects of global climate change on species distributions, yet the physiological mechanisms responsible for reduced performance at high temperatures in air-breathing vertebrates are not clear. We conducted an experiment to examine how oxygen affects three variables exhibited by ectotherms as they heat-gaping threshold, panting threshold, and loss of righting response (the latter indicating the critical thermal maximum)-in two lizard species along an elevational (and therefore environmental oxygen partial pressure) gradient. Oxygen partial pressure did not impact these variables in either species. We also exposed lizards at each elevation to severely hypoxic gas to evaluate their responses to hypoxia. Severely low oxygen partial pressure treatments significantly reduced the gaping threshold, panting threshold, and critical thermal maximum. Further, under these extreme hypoxic conditions, these variables were strongly and positively related to partial pressure of oxygen. In an elevation where both species overlapped, the thermal tolerance of the high elevation species was less affected by hypoxia than that of the low elevation species, suggesting the high elevation species may be adapted to lower oxygen partial pressures. In the high elevation species, female lizards had higher thermal tolerance than males. Our data suggest that oxygen impacts the thermal tolerance of lizards, but only under severely hypoxic conditions, possibly as a result of hypoxia-induced anapyrexia. Copyright © 2017. Published by Elsevier Ltd.

Pancreas Oxygen Persufflation Increases ATP Levels as Shown by Nuclear Magnetic Resonance

PubMed Central

Scott, W.E.; Weegman, B.P.; Ferrer-Fabrega, J.; Stein, S.A.; Anazawa, T.; Kirchner, V.A.; Rizzari, M.D.; Stone, J.; Matsumoto, S.; Hammer, B.E.; Balamurugan, A.N.; Kidder, L.S.; Suszynski, T.M.; Avgoustiniatos, E.S.; Stone, S.G.; Tempelman, L.A.; Sutherland, D.E.R.; Hering, B.J.; Papas, K.K.

2010-01-01

Background Islet transplantation is a promising treatment for type 1 diabetes. Due to a shortage of suitable human pancreata, high cost, and the large dose of islets presently required for long-term diabetes reversal; it is important to maximize viable islet yield. Traditional methods of pancreas preservation have been identified as suboptimal due to insufficient oxygenation. Enhanced oxygen delivery is a key area of improvement. In this paper, we explored improved oxygen delivery by persufflation (PSF), ie, vascular gas perfusion. Methods Human pancreata were obtained from brain-dead donors. Porcine pancreata were procured by en bloc viscerectomy from heparinized donation after cardiac death donors and were either preserved by either two-layer method (TLM) or PSF. Following procurement, organs were transported to a 1.5-T magnetic resonance (MR) system for 31P nuclear magnetic resonance spectroscopy to investigate their bioenergetic status by measuring the ratio of adenosine triphosphate to inorganic phosphate (ATP:Pi) and for assessing PSF homogeneity by MRI. Results Human and porcine pancreata can be effectively preserved by PSF. MRI showed that pancreatic tissue was homogeneously filled with gas. TLM can effectively raise ATP:Pi levels in rat pancreata but not in larger porcine pancreata. ATP:Pi levels were almost undetectable in porcine organs preserved with TLM. When human or porcine organs were preserved by PSF, ATP:Pi was elevated to levels similar to those observed in rat pancreata. Conclusion The methods developed for human and porcine pancreas PSF homogeneously deliver oxygen throughout the organ. This elevates ATP levels during preservation and may improve islet isolation outcomes while enabling the use of marginal donors, thus expanding the usable donor pool. PMID:20692395

Bidirectional Control of Blood Flow by Astrocytes: A Role for Tissue Oxygen and Other Metabolic Factors.

PubMed

Gordon, Grant R J; Howarth, Clare; MacVicar, Brian A

2016-01-01

Altering cerebral blood flow through the control of cerebral vessel diameter is critical so that the delivery of molecules important for proper brain functioning is matched to the activity level of neurons. Although the close relationship of brain glia known as astrocytes with cerebral blood vessels has long been recognized, it is only recently that these cells have been demonstrated to translate information on the activity level and energy demands of neurons to the vasculature. In particular, astrocytes respond to elevations in extracellular glutamate as a consequence of synaptic transmission through the activation of group 1 metabotropic glutamate receptors. These Gq-protein coupled receptors elevate intracellular calcium via IP3 signaling. A close examination of astrocyte endfeet calcium signals has been shown to cause either vasoconstriction or vasodilation. Common to both vasomotor responses is the generation of arachidonic acid in astrocytes by calcium sensitive phospholipase A2. Vasoconstriction ensues from the conversion of arachidonic acid to 20-hydroxyeicosatetraenoic acid, while vasodilation ensues from the production of epoxyeicosatrienoic acids or prostaglandins. Factors that determine whether constrictor or dilatory pathways predominate include brain oxygen, lactate, adenosine as well as nitric oxide. Changing the oxygen level itself leads to many downstream changes that facilitate the switch from vasoconstriction at high oxygen to vasodilation at low oxygen. These findings highlight the importance of astrocytes as sensors of neural activity and metabolism to coordinate the delivery of essential nutrients via the blood to the working cells.

Preservation of high glycolytic phenotype by establishing new acute lymphoblastic leukemia cell lines at physiologic oxygen concentration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sheard, Michael A., E-mail: msheard@chla.usc.edu; Ghent, Matthew V., E-mail: mattghent@gmail.com; Cabral, Daniel J., E-mail: dcabral14@gmail.com

2015-05-15

Cancer cells typically exhibit increased glycolysis and decreased mitochondrial oxidative phosphorylation, and they continue to exhibit some elevation in glycolysis even under aerobic conditions. However, it is unclear whether cancer cell lines employ a high level of glycolysis comparable to that of the original cancers from which they were derived, even if their culture conditions are changed to physiologically relevant oxygen concentrations. From three childhood acute lymphoblastic leukemia (ALL) patients we established three new pairs of cell lines in both atmospheric (20%) and physiologic (bone marrow level, 5%) oxygen concentrations. Cell lines established in 20% oxygen exhibited lower proliferation, survival,more » expression of glycolysis genes, glucose consumption, and lactate production. Interestingly, the effects of oxygen concentration used during cell line initiation were only partially reversible when established cell cultures were switched from one oxygen concentration to another for eight weeks. These observations indicate that ALL cell lines established at atmospheric oxygen concentration can exhibit relatively low levels of glycolysis and these levels are semi-permanent, suggesting that physiologic oxygen concentrations may be needed from the time of cell line initiation to preserve the high level of glycolysis commonly exhibited by leukemias in vivo. - Highlights: • Establishing new ALL cell lines in 5% oxygen resulted in higher glycolytic expression and function. • Establishing new ALL cell lines in 5% oxygen resulted in higher proliferation and lower cell death. • The divergent metabolic phenotypes selected in 5% and 20% oxygen are semi-permanent.« less

Natriuretic Peptide and High-Sensitive Troponin T Concentrations Correlate with Effectiveness of Short-Term CPAP in Patients with Obstructive Sleep Apnea and Coronary Artery Disease.

PubMed

Strehmel, Ralf; Valo, Misa; Teupe, Claudius

2016-01-01

The risk of cardiovascular complications is increased in patients with obstructive sleep apnea (OSA). Continuous positive airway pressure (CPAP) is the most effective way to treat clinically significant OSA. We hypothesized that the concentrations of the cardiac risk markers N-terminal brain natriuretic peptide (NT-proBNP) and high-sensitive troponin T (hs-TropT) correlate with the effectiveness of CPAP therapy in patients with OSA and coexisting coronary artery disease (CAD). Twenty-one patients with severe OSA and coexisting CAD (group 1) and 20 control patients with severe OSA alone (group 2) were treated with CPAP and monitored by laboratory-based polysomnography. NT-proBNP and hs-TropT levels were measured before and after CPAP. Apnea-hypopnea index (AHI) and oxygen desaturation were similar in both groups. In group 1, hs-TropT levels correlated with AHI and oxygen desaturation upon CPAP. Elevated NT-proBNP levels in group 1 were significantly reduced by CPAP. NT-proBNP levels correlated with AHI and showed negative correlation with ST-segment depression. No such correlations were found in group 2. CPAP has the potential to normalize elevated NT-proBNP serum levels in patients with severe OSA and coexisting CAD. Levels of NT-proBNP and hs-TropT correlated with AHI and oxygen desaturation.

Did the Laurentide ice sheet survive through Marine Isotope Stage 9?

NASA Astrophysics Data System (ADS)

Carlson, A. E.; Tarasov, L.; Ullman, D. J.

2016-12-01

Looking at the global benthic oxygen isotope stack, only marine oxygen isotope stage (MIS) 7 stands out as an anomalous interglaciation with a higher oxygen isotope value than other interglaciations of the last half million years. However, benthic oxygen isotopes are an integrator of global ice volume plus temperature, and records of local ice-sheet change are needed to partition the sources of the global signal. Here we use the Laurentide ice-sheet (LIS) proximal record of IODP Site U1302/1303 off of Orphan Knoll to test LIS presence/absence on the eastern Canadian shield. Ice-sheet model calibrated Si relative to Sr is low in most interglaciations of the last 500 ka reflecting the removal of the LIS and its erosive power from the Canadian Shield. However, like MIS 7, MIS 9 has continued elevated inputs of Si. Furthermore, planktic oxygen isotopes do not decrease to full interglacial levels like in MIS 1, 5e and 11. MIS 9 had a similar orbital forcing as MIS 5e, but a much shorter period of elevated interglacial carbon dioxide concentration. Based on climate model simulations of LIS stability, we suggest that the reduced period of elevated atmospheric carbon dioxide allowed the LIS to survive through MIS 9 (like MIS 7), providing important constraints for the climatic thresholds necessary for a full interglaciation.

Forearm Muscle Oxygenation Decreases During Low Levels of Brief, Isometric Contraction

NASA Technical Reports Server (NTRS)

Murthy Gita; Kahan, N. J.; Hargens, Alan R.; Rempel, D. M.; Hargens, Murthy G. (Technical Monitor)

1997-01-01

Regional muscle pain syndromes can be caused by repeated and sustained exertion of a specific muscle. Such exertion may elevate local tissue fluid pressure, reduce blood flow and tissue oxygenation (TO2), and cause fatigue, pain and functional deficits of the Involved muscle. Low levels (less than 20% maximum voluntary contraction (MVC)) of prolonged static contraction of the upper extremity are common In many occupational settings and May cause fatigue. The purpose of our Investigation was to determine whether TO2 decreases significantly at low levels of static contraction of the extensor carpi radialis brevis (ECRB).

Altitude Above Sea Level and Body Mass Index as Determinants of Oxygen Saturation in Children: The SON@ Study.

PubMed

Gochicoa-Rangel, Laura; Pérez-Padilla, José Rogelio; Rodríguez-Moreno, Luis; Montero-Matamoros, Arturo; Ojeda-Luna, Nancy; Martínez-Carbajal, Gema; Hernández-Raygoza, Roberto; Ruiz-Pedraza, Dolores; Fernández-Plata, María Rosario; Torre-Bouscoulet, Luis

2015-01-01

Altitude above sea level and body mass index are well-recognized determinants of oxygen saturation in adult populations; however, the contribution of these factors to oxygen saturation in children is less clear. To explore the contribution of altitude above sea level and body mass index to oxygen saturation in children. A multi-center, cross-sectional study conducted in nine cities in Mexico. Parents signed informed consent forms and completed a health status questionnaire. Height, weight, and pulse oximetry were recorded. We studied 2,200 subjects (52% girls) aged 8.7 ± 3.0 years. Mean body mass index, z-body mass index, and oxygen saturation were 18.1 ± 3.6 kg·m-2, 0.58 ± 1.3, and 95.5 ± 2.4%, respectively. By multiple regression analysis, altitude proved to be the main predictor of oxygen saturation, with non-significant contributions of age, gender, and body mass index. According to quantile regression, the median estimate of oxygen saturation was 98.7 minus 1.7% per km of altitude above sea level, and the oxygen saturation fifth percentile 97.4 minus 2.7% per km of altitude. Altitude was the main determinant of oxygen saturation, which on average decreased 1.7% per km of elevation from a percentage of 98.7 at sea level. In contrast with adults, this study in children found no association between oxygen saturation and obesity or age.

Differences in Hematological Traits between High- and Low-Altitude Lizards (Genus Phrynocephalus)

PubMed Central

Lu, Songsong; Xin, Ying; Tang, Xiaolong; Yue, Feng; Wang, Huihui; Bai, Yucheng; Niu, Yonggang; Chen, Qiang

2015-01-01

Phrynocephalus erythrurus (Lacertilia: Agamidae) is considered to be the highest living reptile in the world (about 4500-5000 m above sea level), whereas Phrynocephalus przewalskii inhabits low altitudes (about 1000-1500 m above sea level). Here, we report the differences in hematological traits between these two different Phrynocephalus species. Compared with P. przewalskii, the results indicated that P. erythrurus own higher oxygen carrying capacity by increasing red blood cell count (RBC), hemoglobin concentration ([Hb]) and hematocrit (Hct) and these elevations could promote oxygen carrying capacity without disadvantage of high viscosity. The lower partial pressure of oxygen in arterial blood (PaO2) of P. erythrurus did not cause the secondary alkalosis, which may be attributed to an efficient pulmonary system for oxygen (O2) loading. The elevated blood-O2 affinity in P. erythrurus may be achieved by increasing intrinsic O2 affinity of isoHbs and balancing the independent effects of potential heterotropic ligands. We detected one α-globin gene and three β-globin genes with 1 and 33 amino acid substitutions between these two species, respectively. Molecular dynamics simulation results showed that amino acids substitutions in β-globin chains could lead to the elimination of hydrogen bonds in T-state Hb models of P. erythrurus. Based on the present data, we suggest that P. erythrurus have evolved an efficient oxygen transport system under the unremitting hypobaric hypoxia. PMID:25955247

In-vitro evaluation of limitations and possibilities for the future use of intracorporeal gas exchangers placed in the upper lobe position.

PubMed

Schumer, Erin; Höffler, Klaus; Kuehn, Christian; Slaughter, Mark; Haverich, Axel; Wiegmann, Bettina

2018-03-01

The lack of donor organs has led to the development of alternative "destination therapies", such as a bio-artificial lung (BA) for end-stage lung disease. Ultimately aiming at a fully implantable BA, general capabilities and limitations of different oxygenators were tested based on the model of BA positioning at the right upper lobe. Three different-sized oxygenators (neonatal, paediatric, and adult) were tested in a mock circulation loop regarding oxygenation and decarboxylation capacities for three respiratory pathologies. Blood flows were imitated by a roller pump, and respiration was imitated by a mechanical ventilator with different FiO 2 applications. Pressure drops across the oxygenators and the integrity of the gas-exchange hollow fibers were analyzed. The neonatal oxygenator proved to be insufficient regarding oxygenation and decarboxylation. Despite elevated pCO 2 levels, the paediatric and adult oxygenators delivered comparable sufficient oxygen levels, but sufficient decarboxylation across the oxygenators was ensured only at flow rates of 0.5 L min. Only the adult oxygenator indicated no significant pressure drops. For all tested conditions, gas-exchange hollow fibers remained intact. This is the first study showing the general feasibility of delivering sufficient levels of gas exchange to an intracorporeal BA via patient's breathing, without damaging gas-exchange hollow fiber membranes.

[Effects of elevated ozone concentrations on reactive oxygen metabolism and related gene expression in Ginkgo biloba leaves].

PubMed

Ruan, Ya Nan; Xu, Sheng; Guo, Long; Zhu, Ming Zhu; Wang, Cong; Li, Shu Yuan; Wang, Hong Yan

2017-11-01

By using the open top chambers (OTCs) fumigation method, this paper investigated the changes of foliar injury, level of reactive oxygen species (ROS), activities and gene expression of antioxidant enzymes in Ginkgo biloba leaves under different ozone (ambient ozone≈40, 80, 160, 200 nmol·mol -1 ) concentrations, in order to study the effects of elevated ozone (O 3 ) concentrations on reactive metabolism. The results showed that the obvious foliar injuries were observed in 160 and 200 nmol·mol -1 O 3 treatments, while no visible injury was observed in 80 nmol·mol -1 O 3 and ambient O 3 treatments. After 20 d, a significant increase in O 2 -· generation rate was observed in G. biloba leaves exposed to 160, 200 nmol·mol -1 O 3 , compared with ambient ozone and 80 nmol·mol -1 O 3 , and there were no significant differences between ambient O 3 and 80 nmol·mol -1 treatments. After 40 d, H 2 O 2 content of G. biloba leaves in 160 and 200 nmol·mol -1 O 3 was significantly higher than that in 80 nmol·mol -1 and ambient ozone, respectively. The activities of catalase (CAT) in 160 and 200 nmol·mol -1 treatments were also significantly higher than that in 80 nmol·mol -1 and ambient O 3 treatments. The ascorbate peroxidase (APX) activity of leaves for each elevated O 3 treatment was lower than that of ambient ozone. The level of CAT and APX expression increased progressively after 40 d O 3 treatment. The expression intensity of GbD was conspicuously strengthened along with the increase of ozone concentration and fumigation time. Le-vel of reactive oxygen increased, activities of antioxidant enzyme decreased, level of gene expression down-regulated, and foliar visible injury was observed in leaves of G. biloba in elevated ozone stress.

Metal ions induced heat shock protein response by elevating superoxide anion level in HeLa cells transformed by HSE-SEAP reporter gene.

PubMed

Yu, Zhanjiang; Yang, Xiaoda; Wang, Kui

2006-06-01

The aim of this work is to define the relationship between heat shock protein (HSP) and reactive oxygen species (ROS) in the cells exposed to different concentrations of metal ions, and to evaluate a new method for tracing the dynamic levels of cellular reactive oxygen species using a HSE-SEAP reporter gene. The expression of heat shock protein was measured using a secreted alkaline phosphatase (SEAP) reporter gene transformed into HeLa cell strain, the levels of superoxide anion (O(2)(-)) and hydrogen peroxide (H(2)O(2)) were determined by NBT reduction assay and DCFH staining flow cytometry (FCM), respectively. The experimental results demonstrated that the expression of heat shock protein induced by metal ions was linearly related to the cellular superoxide anion level before cytotoxic effects were observed, but not related to the cellular hydrogen peroxide level. The experimental results suggested that metal ions might induce heat shock protein by elevating cellular superoxide anion level, and thus the expression of heat shock protein indicated by the HSE-SEAP reporter gene can be an effective model for monitoring the dynamic level of superoxide anion and early metal-induced oxidative stress/cytotoxicity.

Temperature-dependent endogenous oxygen concentration regulates microsomal oleate desaturase in developing sunflower seeds.

PubMed

Rolletschek, Hardy; Borisjuk, Ljudmilla; Sánchez-García, Alicia; Gotor, Cecilia; Romero, Luis C; Martínez-Rivas, José M; Mancha, Manuel

2007-01-01

Oleoyl-phosphatidylcholine desaturase (FAD2) is a key enzyme involved in fatty acid desaturation in oilseeds, which is affected by environmental temperature. The results of this study show that FAD2 is regulated in vivo via temperature-dependent endogenous oxygen concentrations in developing sunflower (Helianthus annuus L.) seeds. By combining in vivo oxygen profiling, in situ hybridization of FAD2 genes, an assay of energy status, fatty acid analysis, and an in vitro FAD2 enzyme activity assay, it is shown that: (i) the oil-storing embryo is characterized by a very low oxygen level that is developmentally regulated. Oxygen supply is mainly limited by the thin seed coat. (ii) Elevations of external oxygen supply raised the energy status of seed and produced a dramatic increase of the FAD2 enzyme activity as well as the linoleic acid content. (iii) A clear negative correlation exists between temperature and internal oxygen concentration. The changes occurred almost instantly and the effect was fully reversible. The results indicate that the internal oxygen level acts as a key regulator for the activity of the FAD2 enzyme. It is concluded that a major mechanism by which temperature modifies the unsaturation degree of the sunflower oil is through its effect on dissolved oxygen levels in the developing seed.

Reactive oxygen species, oxidative stress, glaucoma and hyperbaric oxygen therapy.

PubMed

McMonnies, Charles

This review examines the role of oxidative stress in damage to cells of the trabecular meshwork and associated impaired aqueous drainage as well as damage to retinal ganglion cells and associated visual field losses. Consideration is given to the interaction between vascular and mechanical explanations for pathological changes in glaucoma. For example, elevated intraocular pressure (IOP) forces may contribute to ischaemia but there is increasing evidence that altered blood flow in a wider sense is also involved. Both vascular and mechanical theories are involved through fluctuations in intraocular pressure and dysregulation of blood flow. Retinal function is very sensitive to changes in haemoglobin oxygen concentration and the associated variations in the production of reactive oxygen species. Reperfusion injury and production of reactive oxygen species occurs when IOP is elevated or blood pressure is low and beyond the capacity for blood flow autoregulation to maintain appropriate oxygen concentration. Activities such as those associated with postural changes, muscular effort, eye wiping and rubbing which cause IOP fluctuation, may have significant vascular, mechanical, reperfusion and oxidative stress consequences. Hyperbaric oxygen therapy exposes the eye to increased oxygen concentration and the risk of oxidative damage in susceptible individuals. However, oxygen concentration in aqueous humour, and the risk of damage to trabecular meshwork cells may be greater if hyperbaric oxygen is delivered by a hood which exposes the anterior ocular surface to higher than normal oxygen levels. Oronasal mask delivery of hyperbaric oxygen therapy appears to be indicated in these cases. Copyright © 2017 Spanish General Council of Optometry. Published by Elsevier España, S.L.U. All rights reserved.

Negative impacts of elevated nitrate on physiological performance are not exacerbated by low pH.

PubMed

Gomez Isaza, Daniel F; Cramp, Rebecca L; Franklin, Craig E

2018-05-15

Multiple environmental stressors, including nutrient effluents (i.e. nitrates [NO 3 - ]) and altered pH regimes, influence the persistence of freshwater species in anthropogenically disturbed habitats. Independently, nitrate and low pH affect energy allocation by increasing maintenance costs and disrupting oxygen uptake, which ultimately results in impacts upon whole animal performance. However, the interaction between these two stressors has not been characterised. To address this, the effects of nitrate and pH and their interaction on aerobic scope and physiological performance were investigated in the blueclaw crayfish, Cherax destructor. Crayfish were exposed to a 2 × 3 factorial combination, with two pH levels (pH 5.0 and 7.0) and three nitrate concentrations (0, 50 and 100 mg L -1 NO 3 - ). Crayfish were exposed to experimental conditions for 65 days and growth and survival were monitored. Aerobic scope (i.e. maximal - standard oxygen uptake) was measured at six time points (1, 3, 5, 7, 14, and 21 days) during exposure to experimental treatments. Crayfish performance was assessed after 28 days, by measuring chelae strength and whole animal activity capacity via the righting response. Survival was reduced in crayfish exposed to pH 5.0, but there was no exacerbation of this effect by exposure to high nitrate levels. Aerobic scope was compromised by the interaction between low pH and nitrate and resulted in prolonged elevations of standard oxygen uptake rates. Exposure to nitrate alone affected aerobic scope, causing a 59% reduction in maximum oxygen uptake. Reduced aerobic capacity translated to reduced chelae strength and righting capacity. Together, these data show that low pH and elevated nitrate levels reduce aerobic scope and translate to poorer performance in C. destructor, which may have the potential to affect organismal fitness in disturbed habitats. Copyright © 2018 Elsevier B.V. All rights reserved.

Gene expression profiling reveals decreased expression of two hemoglobin genes associated with increased consumption of oxygen in Chironomus tentans exposed to atrazine: a possible mechanism for adapting to oxygen deficiency.

PubMed

Anderson, Troy D; Jin-Clark, Ying; Begum, Khurshida; Starkey, Sharon R; Zhu, Kun Yan

2008-01-31

Atrazine is an extensively used triazine herbicide in agricultural and residential areas and has been routinely detected in many surface and ground waters. This study reveals various up- and down-regulated genes associated with hypoxic stress in atrazine-treated fourth-instar Chironomus tentans larvae (midges) by using restriction fragment differential display-PCR. Two down-regulated hemoglobin cDNAs were isolated from the midges. Northern blot analysis indicated CteHb-IIbeta and CteHb-III mRNA expressions decreased by 36 and 21%, respectively, in midges exposed to atrazine at 1 microg/L for 96h. Decreased hemoglobin gene expression was associated with elevated oxygen consumption in atrazine-treated midges. Midges exposed to atrazine at 1 microg/L increased their oxygen consumption by 47%, whereas midges exposed to atrazine at 1000 microg/L for 48h increased their oxygen consumption by 66%. Our study demonstrates for the first time that atrazine, at environmentally relevant concentrations, can elevate respiration, possibly eliciting counteractive measures at the transcriptional level to adapt to oxygen deficiency in an ecologically important aquatic insect. Our results further suggest that the ability to modulate both the quantity and quality of Hb serves as an adaptive response to counteract the initial onset of oxygen deficiency induced by atrazine in midges.

Exhaustive Exercise-induced Oxidative Stress Alteration of Erythrocyte Oxygen Release Capacity.

PubMed

Xiong, Yanlian; Xiong, Yanlei; Wang, Yueming; Zhao, Yajin; Li, Yaojin; Ren, Yang; Wang, Ruofeng; Zhao, Mingzi; Hao, Yitong; Liu, Haibei; Wang, Xiang

2018-05-24

The aim of the present study is to explore the effect of exhaustive running exercise (ERE) in the oxygen release capacity of rat erythrocytes. Rats were divided into sedentary control (C), moderate running exercise (MRE) and exhaustive running exercise groups. The thermodynamics and kinetics properties of the erythrocyte oxygen release process of different groups were tested. We also determined the degree of band-3 oxidative and phosphorylation, anion transport activity and carbonic anhydrase isoform II(CAII) activity. Biochemical studies suggested that exhaustive running significantly increased oxidative injury parameters in TBARS and methaemoglobin levels. Furthermore, exhaustive running significantly decreased anion transport activity and carbonic anhydrase isoform II(CAII) activity. Thermodynamic analysis indicated that erythrocytes oxygen release ability also significantly increased due to elevated 2,3-DPG level after exhaustive running. Kinetic analysis indicated that exhaustive running resulted in significantly decreased T50 value. We presented evidence that exhaustive running remarkably impacted thermodynamics and kinetics properties of RBCs oxygen release. In addition, changes in 2,3-DPG levels and band-3 oxidation and phosphorylation could be the driving force for exhaustive running induced alterations in erythrocytes oxygen release thermodynamics and kinetics properties.

Differential responses of juvenile and adult South African abalone (Haliotis midae Linnaeus) to low and high oxygen levels.

PubMed

Vosloo, Andre; Laas, Anél; Vosloo, Dalene

2013-01-01

Marine invertebrates have evolved multiple responses to naturally variable environmental oxygen, all aimed at either maintaining cellular oxygen homeostasis or limiting cellular damage during or after hypoxic or hyperoxic events. We assessed organismal (rates of oxygen consumption and ammonia excretion) and cellular (heat shock protein expression, anti-oxidant enzymes) responses of juvenile and adult abalone exposed to low (~83% of saturation), intermediate (~95% of saturation) and high (~115% of saturation) oxygen levels for one month. Using the Comet assay, we measured DNA damage to determine whether the observed trends in the protective responses were sufficient to prevent oxidative damage to cells. Juveniles were unaffected by moderately hypoxic and hyperoxic conditions. Elevated basal rates of superoxide dismutase, glutathione peroxidase and catalase were sufficient to prevent DNA fragmentation and protein damage. Adults, with their lower basal rate of anti-oxidant enzymes, had increased DNA damage under hypoxic and hyperoxic conditions, indicating that the antioxidant enzymes were unable to prevent oxidative damage under hypoxic and hyperoxic conditions. The apparent insensitivity of juvenile abalone to decreased and increased oxygen might be related to their life history and development in algal and diatom biofilms where they are exposed to extreme diurnal fluctuations in dissolved oxygen levels. Copyright © 2012 Elsevier Inc. All rights reserved.

Increased blood glycohemoglobin A1c levels lead to overestimation of arterial oxygen saturation by pulse oximetry in patients with type 2 diabetes

PubMed Central

2012-01-01

Background Non-enzymatic glycation increases hemoglobin-oxygen affinity and reduces oxygen delivery to tissues by altering the structure and function of hemoglobin. Objectives We investigated whether an elevated blood concentration of glycosylated hemoglobin (HbA1c) could induce falsely high pulse oximeter oxygen saturation (SpO2) in type 2 diabetic patients during mechanical ventilation or oxygen therapy. Methods Arterial oxygen saturation (SaO2) and partial pressure of oxygen (PO2) were determined with simultaneous monitoring of SpO2 in 261 type 2 diabetic patients during ventilation or oxygen inhalation. Results Blood concentration of HbA1c was >7% in 114 patients and ≤ 7% in 147 patients. Both SaO2 (96.2 ± 2.9%, 95% confidence interval [CI] 95.7-96.7% vs. 95.1 ± 2.8%, 95% CI 94.7-95.6%) and SpO2 (98.0 ± 2.6%, 95% CI 97.6-98.5% vs. 95.3 ± 2.8%, 95% CI 94.9-95.8%) were significantly higher in patients with HbA1c >7% than in those with HbA1c ≤ 7% (Data are mean ± SD, all p < 0.01), but PO2 did not significantly differ between the two groups. Bland-Altman analysis demonstrated a significant bias between SpO2 and SaO2 (1.83 ±0.55%, 95% CI 1.73% -1.94%) and limits of agreement (0.76% and 2.92%) in patients with HbA1c >7%. The differences between SpO2 and SaO2 correlated closely with blood HbA1c levels (Pearson’s r = 0.307, p < 0.01). Conclusions Elevated blood HbA1c levels lead to an overestimation of SaO2 by SpO2, suggesting that arterial blood gas analysis may be needed for type 2 diabetic patients with poor glycemic control during the treatment of hypoxemia. PMID:22985301

Increased blood glycohemoglobin A1c levels lead to overestimation of arterial oxygen saturation by pulse oximetry in patients with type 2 diabetes.

PubMed

Pu, Li Jin; Shen, Ying; Lu, Lin; Zhang, Rui Yan; Zhang, Qi; Shen, Wei Feng

2012-09-17

Non-enzymatic glycation increases hemoglobin-oxygen affinity and reduces oxygen delivery to tissues by altering the structure and function of hemoglobin. We investigated whether an elevated blood concentration of glycosylated hemoglobin (HbA1c) could induce falsely high pulse oximeter oxygen saturation (SpO2) in type 2 diabetic patients during mechanical ventilation or oxygen therapy. Arterial oxygen saturation (SaO2) and partial pressure of oxygen (PO2) were determined with simultaneous monitoring of SpO2 in 261 type 2 diabetic patients during ventilation or oxygen inhalation. Blood concentration of HbA1c was >7% in 114 patients and ≤ 7% in 147 patients. Both SaO2 (96.2 ± 2.9%, 95% confidence interval [CI] 95.7-96.7% vs. 95.1 ± 2.8%, 95% CI 94.7-95.6%) and SpO2 (98.0 ± 2.6%, 95% CI 97.6-98.5% vs. 95.3 ± 2.8%, 95% CI 94.9-95.8%) were significantly higher in patients with HbA1c >7% than in those with HbA1c ≤ 7% (Data are mean ± SD, all p < 0.01), but PO2 did not significantly differ between the two groups. Bland-Altman analysis demonstrated a significant bias between SpO2 and SaO2 (1.83 ±0.55%, 95% CI 1.73% -1.94%) and limits of agreement (0.76% and 2.92%) in patients with HbA1c >7%. The differences between SpO2 and SaO2 correlated closely with blood HbA1c levels (Pearson's r = 0.307, p < 0.01). Elevated blood HbA1c levels lead to an overestimation of SaO2 by SpO2, suggesting that arterial blood gas analysis may be needed for type 2 diabetic patients with poor glycemic control during the treatment of hypoxemia.

Oxidative stress in deep scattering layers: Heat shock response and antioxidant enzymes activities of myctophid fishes thriving in oxygen minimum zones

NASA Astrophysics Data System (ADS)

Lopes, Ana Rita; Trübenbach, Katja; Teixeira, Tatiana; Lopes, Vanessa M.; Pires, Vanessa; Baptista, Miguel; Repolho, Tiago; Calado, Ricardo; Diniz, Mário; Rosa, Rui

2013-12-01

Diel vertical migrators, such as myctophid fishes, are known to encounter oxygen minimum zones (OMZ) during daytime in the Eastern Pacific Ocean and, therefore, have to cope with temperature and oxidative stress that arise while ascending to warmer, normoxic surface waters at night-time. The aim of this study was to investigate the antioxidant defense strategies and heat shock response (HSR) in two myctophid species, namely Triphoturus mexicanus and Benthosema panamense, at shallow and warm surface waters (21 kPa, 20-25 °C) and at hypoxic, cold (≤1 kPa, 10 °C) mesopelagic depths. More specifically, we quantified (i) heat shock protein concentrations (HSP70/HSC70) (ii) antioxidant enzyme activities [including superoxide dismutase (SOD), catalase (CAT) and glutathione-S-transferase (GST)], and (iii) lipid peroxidation [malondialdehyde (MDA) levels]. HSP70/HSC70 levels increased in both myctophid species at warmer, well-oxygenated surface waters probably to prevent cellular damage (oxidative stress) due to increased oxygen demand under elevated temperatures and reactive oxygen species (ROS) formation. On the other hand, CAT and GST activities were augmented under hypoxic conditions, probably as preparatory response to a burst of oxyradicals during the reoxygenation phase (while ascending). SOD activity decreased under hypoxia in B. panamense, but was kept unchanged in T. mexicanus. MDA levels in B. panamense did not change between the surface and deep-sea conditions, whereas T. mexicanus showed elevated MDA and HSP70/HSC70 concentrations at warmer surface waters. This indicated that T. mexicanus seems to be not so well tuned to temperature and oxidative stress associated to diel vertical migrations. The understanding of such physiological strategies that are linked to oxygen deprivation and reoxygenation phases may provide valuable information about how different species might respond to the impacts of environmental stressors (e.g. expanding mesopelagic hypoxia) coupled with global climate change.

The effect of carbon dioxide on the twinkling artifact in ultrasound imaging of kidney stones: A pilot study

PubMed Central

Simon, Julianna C.; Wang, Yak-Nam; Cunitz, Bryan W.; Thiel, Jeffrey; Starr, Frank; Liu, Ziyue; Bailey, Michael R.

2016-01-01

Bone demineralization, dehydration, and stasis put astronauts at an increased risk of forming kidney stones in space. The color-Doppler ultrasound “twinkling artifact”, which highlights kidney stones with color, can make stones readily detectable with ultrasound; however our previous results suggest twinkling is caused by microbubbles on the stone surface which could be affected by the elevated levels of carbon dioxide found on space vehicles. Four pigs were implanted with kidney stones and imaged with ultrasound while the anesthetic carrier gas oscillated between oxygen and air containing 0.8% carbon dioxide. Upon exposing pigs to 0.8% carbon dioxide, twinkling was significantly reduced after 9–25 minutes and recovered when the carrier gas returned to oxygen. These trends repeated when pigs were again exposed to 0.8% carbon dioxide followed by oxygen. The reduction of twinkling from exposure to elevated carbon dioxide may make kidney stone detection with twinkling difficult in current space vehicles. PMID:28190622

Effect of elevated pCO2 on metabolic responses of porcelain crab (Petrolisthes cinctipes) Larvae exposed to subsequent salinity stress.

PubMed

Miller, Seth H; Zarate, Sonia; Smith, Edmund H; Gaylord, Brian; Hosfelt, Jessica D; Hill, Tessa M

2014-01-01

Future climate change is predicted to alter the physical characteristics of oceans and estuaries, including pH, temperature, oxygen, and salinity. Investigating how species react to the influence of such multiple stressors is crucial for assessing how future environmental change will alter marine ecosystems. The timing of multiple stressors can also be important, since in some cases stressors arise simultaneously, while in others they occur in rapid succession. In this study, we investigated the effects of elevated pCO2 on oxygen consumption by larvae of the intertidal porcelain crab Petrolisthes cinctipes when exposed to subsequent salinity stress. Such an exposure mimics how larvae under future acidified conditions will likely experience sudden runoff events such as those that occur seasonally along portions of the west coast of the U.S. and in other temperate systems, or how larvae encounter hypersaline waters when crossing density gradients via directed swimming. We raised larvae in the laboratory under ambient and predicted future pCO2 levels (385 and 1000 µatm) for 10 days, and then moved them to seawater at ambient pCO2 but with decreased, ambient, or elevated salinity, to monitor their respiration. While larvae raised under elevated pCO2 or exposed to stressful salinity conditions alone did not exhibit higher respiration rates than larvae held in ambient conditions, larvae exposed to elevated pCO2 followed by stressful salinity conditions consumed more oxygen. These results show that even when multiple stressors act sequentially rather than simultaneously, they can retain their capacity to detrimentally affect organisms.

Effect of Elevated pCO2 on Metabolic Responses of Porcelain Crab (Petrolisthes cinctipes) Larvae Exposed to Subsequent Salinity Stress

PubMed Central

Miller, Seth H.; Zarate, Sonia; Smith, Edmund H.; Gaylord, Brian; Hosfelt, Jessica D.; Hill, Tessa M.

2014-01-01

Future climate change is predicted to alter the physical characteristics of oceans and estuaries, including pH, temperature, oxygen, and salinity. Investigating how species react to the influence of such multiple stressors is crucial for assessing how future environmental change will alter marine ecosystems. The timing of multiple stressors can also be important, since in some cases stressors arise simultaneously, while in others they occur in rapid succession. In this study, we investigated the effects of elevated pCO2 on oxygen consumption by larvae of the intertidal porcelain crab Petrolisthes cinctipes when exposed to subsequent salinity stress. Such an exposure mimics how larvae under future acidified conditions will likely experience sudden runoff events such as those that occur seasonally along portions of the west coast of the U.S. and in other temperate systems, or how larvae encounter hypersaline waters when crossing density gradients via directed swimming. We raised larvae in the laboratory under ambient and predicted future pCO2 levels (385 and 1000 µatm) for 10 days, and then moved them to seawater at ambient pCO2 but with decreased, ambient, or elevated salinity, to monitor their respiration. While larvae raised under elevated pCO2 or exposed to stressful salinity conditions alone did not exhibit higher respiration rates than larvae held in ambient conditions, larvae exposed to elevated pCO2 followed by stressful salinity conditions consumed more oxygen. These results show that even when multiple stressors act sequentially rather than simultaneously, they can retain their capacity to detrimentally affect organisms. PMID:25295878

Surface modification effects of fluorine-doped tin dioxide by oxygen plasma ion implantation

NASA Astrophysics Data System (ADS)

Tang, Peng; Liu, Cai; Zhang, Jingquan; Wu, Lili; Li, Wei; Feng, Lianghuan; Zeng, Guanggen; Wang, Wenwu

2018-04-01

SnO2:F (FTO), as a kind of transparent conductive oxide (TCO), exhibits excellent transmittance and conductivity and is widely used as transparency electrodes in solar cells. It's very important to modifying the surface of FTO for it plays a critical role in CdTe solar cells. In this study, modifying effects of oxygen plasma on FTO was investigated systematically. Oxygen plasma treatment on FTO surface with ion accelerating voltage ranged from 0.4 kV to 1.6 kV has been processed. The O proportion of surface was increased after ion implantation. The Fermi level of surface measurement by XPS valance band spectra was lowered as the ion accelerating voltage increased to 1.2 kV and then raised as accelerating voltage was elevated to 1.6 kV. The work function measured by Kelvin probe force microscopy increased after ion implanting, and it was consistent with the variation of Fermi level. The change of energy band structure of FTO surface mainly originated from the surface composition variation. As FTO conduction was primarily due to oxyanion hole, the carrier was electron and its concentration was reduced while O proportion was elevated at the surface of FTO, as a result, the Fermi level lowered and the work function was enlarged. It was proved that oxygen plasma treatment is an effective method to modulate the energy band structure of the surface as well as other properties of FTO, which provides much more space for interface and surface modification and then photoelectric device performance promotion.

Importance of measuring lactate levels in children with sepsis.

PubMed

Anil, Nisha

2017-10-10

Sepsis is a major public health problem as well as one of the leading causes of preventable death in children because of failure to recognise the early signs and symptoms and to resuscitate rapidly. Blood lactate levels are used to assess the severity of sepsis and the effectiveness of resuscitation. Lactate levels are easily obtainable and should be checked in all patients admitted with suspected sepsis within six hours of presentation. The test should be repeated four and eight-hours post-diagnosis of sepsis. For the diagnosis of sepsis, patients' clinical symptoms, along with the combined analysis of partial pressure of oxygen, carbon dioxide and lactate levels, should be used. A multitude of factors can cause elevated lactate levels and so clinicians should use elevated levels cautiously by considering all other aetiologies. This article, which focuses on practice in Australia but makes reference to the UK, discusses the importance of measuring lactate levels in sepsis, the pathophysiology of lactate production, causes of elevated lactate levels, lactate measurement, nursing management of patients with elevated lactate levels, limitations of using lactate as a biomarker for diagnosing sepsis and implications for practice. ©2012 RCN Publishing Company Ltd. All rights reserved. Not to be copied, transmitted or recorded in any way, in whole or part, without prior permission of the publishers.

Oxidative stress and antioxidant biomarker responses after a moderate-intensity soccer training session.

PubMed

Mello, Rodrigo; Mello, Ricardo; Gomes, Diego; Paz, Gabriel Andrade; Nasser, Igor; Miranda, Humberto; Salerno, Verônica P

2017-01-01

The present study investigated the effects of a moderate-intensity soccer training session on the production of reactive oxygen species (ROS) and the antioxidant capacity in athletes along with the biomarkers creatine kinase and transaminases for lesions in muscle and liver cells. Twenty-two male soccer players participated in this study. Blood samples were collected 5 min before and after a moderate-intensity game simulation. The results showed a decrease in the concentration of reduced glutathione (GSH) from an elevation in the production of ROS that maintained the redox homeostasis. Although the session promoted an elevated energy demand, observed by an increase in lactate and glucose levels, damage to muscle and/or liver cells was only suggested by a significant elevation in the levels of alanine transaminase (ALT). Of the two biomarkers analysed, the results suggest that measurements of the ALT levels could be adopted as a method to monitor recovery in athletes.

Magnetic nanoparticles: reactive oxygen species generation and potential therapeutic applications

NASA Astrophysics Data System (ADS)

Mai, Trang; Hilt, J. Zach

2017-07-01

Magnetic nanoparticles have been demonstrated to produce reactive oxygen species (ROS), which play a major role in various cellular pathways, via Fenton and Haber-Weiss reaction. ROS act as a double-edged sword inside the body. At normal conditions, the generation of ROS is in balance with their elimination by scavenger systems, and they can promote cell proliferation as well as differentiation. However, at an increased level, they can cause damages to protein, lead to cellular apoptosis, and contribute to many diseases including cancer. Many recent studies proposed a variety of strategies to either suppress toxicity of ROS generation or exploit the elevated ROS levels for cancer therapy.

An elevated level of copper zinc superoxide dismutase fails to prevent oxygen induced retinopathy in mice.

PubMed

Klaeger, C; de Sa, L; Klaeger, A J; Carlson, E J; Good, W V; Epstein, C J

1996-05-01

To determine whether a higher level of copper zinc superoxide dismutase (CuZnSOD) can reduce the severity of oxygen induced retinopathy (OIR) in a mouse model. CuZnSOD transgenic mice with a threefold increase in CuZnSOD activity and control non-transgenic mice were exposed to 90% oxygen for 12 hours a day during the first 5 days of life. After oxygen treatment, all mice were reared in room air for 10 days. Another group of transgenic and non-transgenic mice were kept in room air for 15 days and served as control groups for the oxygen effect. At day 15, all mice were killed and perfused with India ink. The retinas were flat mounted on slides and examined with a light microscope. There was a statistically significant increase in the incidence of OIR in mice exposed to high levels of oxygen, whether or not they were transgenic. However, there was no statistically significant difference in the severity of OIR between oxygen treated transgenic and non-transgenic mice. A threefold higher CuZnSOD activity does not protect against OIR in mice. This is an unexpected finding, since oxygen radicals are considered a major factor causing OIR, and increased CuZnSOD activity has reduced oxygen radical induced damage in several neuronal and non-neuronal systems. The possibility of a damaging role for other radicals not affected by CuZnSOD cannot be excluded.

Probing the Molecular Mechanism of Hypericin-Induced Parasite Death Provides Insight into the Role of Spermidine beyond Redox Metabolism in Leishmania donovani

PubMed Central

Singh, Shalini; Sarma, Shyamali; Katiyar, Shashank P.; Das, Mousumi; Bhardwaj, Ruchika; Sundar, Durai

2014-01-01

Hypericin, a natural compound from Hypericum perforatum (St. John's wort), has been identified as a specific inhibitor of Leishmania donovani spermidine synthase (LdSS) using integrated computational and biochemical approaches. Hypericin showed in vitro inhibition of recombinant LdSS enzyme activity. The in vivo estimation of spermidine levels in Leishmania promastigotes after hypericin treatment showed significant decreases in the spermidine pools of the parasites, indicating target specificity of the inhibitor molecule. The inhibitor, hypericin, showed significant antileishmanial activity, and the mode of death showed necrosis-like features. Further, decreased trypanothione levels and increased glutathione levels with elevated reactive oxygen species (ROS) levels were observed after hypericin treatment. Supplementation with trypanothione in the medium with hypericin treatment restored in vivo trypanothione levels and ROS levels but could not prevent necrosis-like death of the parasites. However, supplementation with spermidine in the medium with hypericin treatment restored in vivo spermidine levels and parasite death was prevented to a large extent. The data overall suggest that the parasite death due to spermidine starvation as a result of LdSS inhibition is not related to elevated levels of reactive oxygen species. This suggests the involvement of spermidine in processes other than redox metabolism in Leishmania parasites. Moreover, the work provides a novel scaffold, i.e., hypericin, as a potent antileishmanial molecule. PMID:25313212

Lack of Methemoglobin Elevations After Topical Applications of Benzocaine Alone or Benzocaine Plus Tetracaine to the Oral Mucosa.

PubMed

Wang, Steven; Giannakopoulos, Helen; Lowstetter, Jamie; Kaye, Laura; Lee, Catherine; Secreto, Stacey; Ho, Vanessa; Hutcheson, Matthew C; Farrar, John T; Wang, Ping; Doyle, Geraldine; Cooper, Stephen A; Hersh, Elliot V

2017-10-01

This study evaluated changes in methemoglobin and oxygen saturation concentrations after the administration of recommended doses of 14% benzocaine alone or 14% benzocaine combined with 2% tetracaine. American Society of Anesthesiology class 1 and 2 subjects (n = 40) were enrolled in this modified crossover study. Subjects were administered 0.2 mL of 14% benzocaine alone, 0.2 mL of 14% benzocaine plus 2% tetracaine, or 0.4 mL of 14% benzocaine plus 0.2% benzocaine to their cheek mucosa. Venous blood (5 mL) was drawn from the antecubital fossa before and 60 minutes after drug application for methemoglobin analyses. Oxygen saturation was also recorded via pulse oximetry at baseline and every 10 minutes through 60 minutes after drug application. Methemoglobin and oxygen saturation levels did not change from baseline after the administration of benzocaine alone or when combined with tetracaine. Recommended doses of benzocaine or benzocaine combined with tetracaine when applied to the cheek mucosa do not induce even clinically insignificant elevations in methemoglobin levels. Metered dosing, such as that used in this study, can help avoid this overdose phenomena with these drugs. ClinicalTrials.gov identifier: NCT02908620. Copyright © 2017 Elsevier HS Journals, Inc. All rights reserved.

Blood Transfusion Therapy in Patients with Heart Disease.

DTIC Science & Technology

1982-04-07

Delivoria-Papadopoulos M, Miller WW. Red cell 2,3 diphosphoglycerate levels in subjects with chronic hypoxemia. N Engl J Med 1969;280:1165-66. I 60...solution will do this. Red cells with elevated 2,3 DPG levels do ensure optimum delivery of oxygen to tissue, especially during hypothermia, although...increased in congestive heart failure. More- over, certain drugs may reduce plasma volume and raise the hematocrit level , and splenomegaly will further reduce

Influence of glutamate-evoked pain and sustained elevated muscle activity on blood oxygenation in the human masseter muscle.

PubMed

Suzuki, Shunichi; Arima, Taro; Kitagawa, Yoshimasa; Svensson, Peter; Castrillon, Eduardo

2017-12-01

This study aimed to investigate the effect of glutamate-evoked masseter muscle pain on intramuscular oxygenation during rest and sustained elevated muscle activity (SEMA). Seventeen healthy individuals participated in two sessions in which they were injected with glutamate and saline in random order. Each session was divided into three, 10-min periods. During the first (period 1) and the last (period 3) 10-min periods, participants performed five intercalated 1-min bouts of masseter SEMA with 1-min periods of 'rest'. At onset of the second 10-min period, glutamate (0.5 ml, 1 M; Ajinomoto, Tokyo, Japan) or isotonic saline (0.5 ml; 0.9%) was injected into the masseter muscle and the participants kept the muscle relaxed in a resting position for 10 min (period 2). The hemodynamic characteristics of the masseter muscle were recorded simultaneously during the experiment by a laser blood-oxygenation monitor. The results demonstrated that glutamate injections caused significant levels of self-reported pain in the masseter muscle; however, this nociceptive input did not have robust effects on intramuscular oxygenation during rest or SEMA tasks. Interestingly, these findings suggest an uncoupling between acute nociceptive activity and hemodynamic parameters in both resting and low-level active jaw muscles. Further studies are needed to explore the pathophysiological significance of blood-flow changes for persistent jaw-muscle pain conditions. © 2017 Eur J Oral Sci.

Jumonji Domain Containing Protein 6: A Novel Oxygen Sensor in the Human Placenta.

PubMed

Alahari, Sruthi; Post, Martin; Caniggia, Isabella

2015-08-01

Persistent low oxygen is implicated in the pathogenesis of placental-associated pathologies such as preeclampsia, a serious disorder of pregnancy. Emerging evidence implicates a novel family of Jumonji C catalytic domain proteins as mediators of hypoxic gene expression. Here, we investigated the regulatory relationship between Jumonji C domain containing protein 6 (JMJD6) and hypoxia-inducible factor (HIF)1A in the human placenta at physiological and pathological conditions. JMJD6 expression inversely correlated with changes in oxygen tension during early placental development, ie, high at 7-9 weeks when-partial pressure of O2 is low and declining afterwards when-partial pressure of O2 increases. Moreover, JMJD6 protein was significantly elevated in early-onset preeclamptic placentae, localizing to the syncytiotrophoblast layer and syncytial knots. Exposure of primary isolated trophoblast cells, human villous explants, and JEG3 choriocarcinoma cells to low oxygen (3%) and sodium nitroprusside (inducer of oxidative stress) also resulted in elevated JMJD6 levels, which was abrogated by HIF1A knockdown. In normoxia, knockdown of JMJD6 in JEG3 cells stabilized HIF1A with a concomitant decrease in von Hippel-Lindau (VHL) tumor suppressor protein, a negative regulator of HIF1A stability. In contrast, overexpression of JMJD6 enhanced VHL expression and destabilized HIF1A. JMJD6 regulation of VHL stability did not involve the ubiquitin-proteasome system but likely occurred through lysyl hydroxylation and small ubiquitin-like modifier 1-dependent small ubiquitin-like modifierylation. In summary, our data signify a novel role for JMJD6 as an oxygen sensor in the human placenta, and alterations in the JMJD6-VHL-HIF1A feedback loop may indirectly contribute to elevated HIF1A found in preeclampsia.

The importance of physiological oxygen concentrations in the sandwich cultures of rat hepatocytes on gas-permeable membranes.

PubMed

Xiao, Wenjin; Shinohara, Marie; Komori, Kikuo; Sakai, Yasuyuki; Matsui, Hitoshi; Osada, Tomoharu

2014-01-01

Oxygen supply is a critical issue in the optimization of in vitro hepatocyte microenvironments. Although several strategies have been developed to balance complex oxygen requirements, these techniques are not able to accurately meet the cellular oxygen demand. Indeed, neither the actual oxygen concentration encountered by cells nor the cellular oxygen consumption rates (OCR) was assessed. The aim of this study is to define appropriate oxygen conditions at the cell level that could accurately match the OCR and allow hepatocytes to maintain liver specific functions in a normoxic environment. Matrigel overlaid rat hepatocytes were cultured on the polydimethylsiloxane (PDMS) membranes under either atmospheric oxygen concentration [20%-O2 (+)] or physiological oxygen concentrations [10%-O2 (+), 5%-O2 (+)], respectively, to investigate the effects of various oxygen concentrations on the efficient functioning of hepatocytes. In parallel, the gas-impermeable cultures (polystyrene) with PDMS membrane inserts were used as the control groups [PS-O2 (-)]. The results indicated that the hepatocytes under 10%-O2 (+) exhibited improved survival and maintenance of metabolic activities and functional polarization. The dramatic elevation of cellular OCR up to the in vivo liver rate proposed a normoxic environment for hepatocytes, especially when comparing with PS-O2 (-) cultures, in which the cells generally tolerated hypoxia. Additionally, the expression levels of 84 drug-metabolism genes were the closest to physiological levels. In conclusion, this study clearly shows the benefit of long-term culture of hepatocytes at physiological oxygen concentration, and indicates on an oxygen-permeable membrane system to provide a simple method for in vitro studies. © 2014 American Institute of Chemical Engineers.

Diaphorina citri (Hemiptera: Liviidae) Abundance in Puerto Rico Declines with Elevation.

PubMed

Jenkins, David A; Hall, David G; Goenaga, Ricardo

2015-02-01

Diaphorina citri Kuwayama is the primary vector of Huanglongbing, the most devastating disease of citrus. D. citri populations in Puerto Rico were monitored with yellow sticky traps on citrus trees or other psyllid host plants at different elevations, ranging from 10 to 880 m above sea level. Trapping was conducted in March through May of 2013 and 2014 when psyllid populations usually are highest. Population levels of D. citri, based on the trapping data, varied among the sites, and there was a strong trend in both years for decreasing psyllid abundance with increased elevation based on the number of psyllids captured on traps and the proportion of trees shown to be infested. No psyllids were collected at an elevation of >600 m. Reduced populations at higher elevations could be a consequence of differences in temperature, air pressure, oxygen levels, ultraviolet light, or other factors alone or in combination. We discuss our results as they pertain to management of D. citri and Huanglongbing. Published by Oxford University Press on behalf of Entomological Society of America. 2015. This work is written by US Government employees and is in the public domain in the US.

Mitochondrial DNA markers reveal high genetic diversity but low genetic differentiation in the black fly Simulium tani Takaoka & Davies along an elevational gradient in Malaysia.

PubMed

Low, Van Lun; Adler, Peter H; Takaoka, Hiroyuki; Ya'cob, Zubaidah; Lim, Phaik Eem; Tan, Tiong Kai; Lim, Yvonne A L; Chen, Chee Dhang; Norma-Rashid, Yusoff; Sofian-Azirun, Mohd

2014-01-01

The population genetic structure of Simulium tani was inferred from mitochondria-encoded sequences of cytochrome c oxidase subunits I (COI) and II (COII) along an elevational gradient in Cameron Highlands, Malaysia. A statistical parsimony network of 71 individuals revealed 71 haplotypes in the COI gene and 43 haplotypes in the COII gene; the concatenated sequences of the COI and COII genes revealed 71 haplotypes. High levels of genetic diversity but low levels of genetic differentiation were observed among populations of S. tani at five elevations. The degree of genetic diversity, however, was not in accordance with an altitudinal gradient, and a Mantel test indicated that elevation did not have a limiting effect on gene flow. No ancestral haplotype of S. tani was found among the populations. Pupae with unique structural characters at the highest elevation showed a tendency to form their own haplotype cluster, as revealed by the COII gene. Tajima's D, Fu's Fs, and mismatch distribution tests revealed population expansion of S. tani in Cameron Highlands. A strong correlation was found between nucleotide diversity and the levels of dissolved oxygen in the streams where S. tani was collected.

Orion Emergency Mask Approach

NASA Technical Reports Server (NTRS)

Tuan, George C.; Graf, John C.

2008-01-01

Emergency mask approach on Orion poses a challenge to the traditional Shuttle or Station approaches. Currently, in the case of a fire or toxic spill event, the crew utilizes open loop oxygen masks that provide the crew with oxygen to breath, but also dumps the exhaled oxygen into the cabin. For Orion, with a small cabin volume, the extra oxygen will exceed the flammability limit within a short period of time, unless a nitrogen purge is also provided. Another approach to a fire or toxic spill event is the use of a filtering emergency masks. These masks utilize some form of chemical beds to scrub the air clean of toxic providing the crew safe breathing air for a period without elevating the oxygen level in the cabin. Using the masks and a form of smoke-eater filter, it may be possible to clean the cabin completely or to a level for safe transition to a space suit to perform a cabin purge. Issues with filters in the past have been the reaction temperature and high breathing resistance. Development in a new form of chemical filters has shown promise to make the filtering approach feasible.

Orion Emergency Mask Approach

NASA Technical Reports Server (NTRS)

Tuan, George C.; Graf, John C.

2009-01-01

Emergency mask approach on Orion poses a challenge to the traditional Shuttle or Station approaches. Currently, in the case of a fire or toxic spill event, the crew utilizes open loop oxygen masks that provide the crew with oxygen to breath, but also dumps the exhaled oxygen into the cabin. For Orion, with a small cabin volume, the extra oxygen will exceed the flammability limit within a short period of time, unless a nitrogen purge is also provided. Another approach to a fire or toxic spill event is the use of a filtering emergency masks. These masks utilize some form of chemical beds to scrub the air clean of toxic providing the crew safe breathing air for a period without elevating the oxygen level in the cabin. Using the masks and a form of smoke-eater filter, it may be possible to clean the cabin completely or to a level for safe transition to a space suit to perform a cabin purge. Issues with filters in the past have been the reaction time, breakthroughs, and high breathing resistance. Development in a new form of chemical filters has shown promise to make the filtering approach feasible.

Water electrolysis

NASA Technical Reports Server (NTRS)

Schubert, Franz H. (Inventor); Grigger, David J. (Inventor)

1992-01-01

This disclosure is directed to an electrolysis cell forming hydrogen and oxygen at space terminals. The anode terminal is porous and able to form oxygen within the cell and permit escape of the gaseous oxygen through the anode and out through a flow line in the presence of backpressure. Hydrogen is liberated in the cell at the opposing solid metal cathode which is permeable to hydrogen but not oxygen so that the migratory hydrogen formed in the cell is able to escape from the cell. The cell is maintained at an elevated pressure so that the oxygen liberated by the cell is delivered at elevated pressure without pumping to raise the pressure of the oxygen.

Measurement of predation and biofilm formation under different ambient oxygen conditions using a simple gasbag-based system.

PubMed

Kadouri, Daniel E; Tran, Aimy

2013-09-01

Bdellovibrio bacteriovorus and Micavibrio aeruginosavorus are Gram-negative bacteria characterized by predatory behavior. The aim of this study was to evaluate the ability of the predators to prey in different oxygen environments. When placed on an orbital shaker, a positive association between the rate of aeration and predation was observed. To further examine the effects of elevated ambient oxygen levels on predation, a simple gasbag system was developed. Using the system, we were able to conduct experiments at ambient oxygen levels of 3% to 86%. When placed in gasbags and inflated with air, 50% O2, and 100% O2, positive predation was seen on both planktonic and biofilm-grown prey cells. However, in low-oxygen environments, predatory bacteria were able to attack only prey cells grown as biofilms. To further evaluate the gasbag system, biofilm development of Gram-positive and Gram-negative microorganisms was also measured. Although the gasbag system was found to be suitable for culturing bacteria that require a low-oxygen environment, it was not capable of supporting, with its current configuration, the growth of obligate anaerobes in liquid or agar medium.

Sources and transport of sediment, nutrients, and oxygen-demanding substances in the Minnesota River basin, 1989-92

USGS Publications Warehouse

Payne, G.A.

1994-01-01

The Minnesota River, 10 major tributaries, and 21 springs were sampled to determine the sources and transport of sediment, nutrients, and oxygen- demanding substances. The study was part of a four-year assessment of non-point source pollution in the Minnesota River Basin. Runoff from tributary watersheds was identified as the primary source of suspended sediment and nutrients in the Minnesota River mainstem. Suspended-sediment, phosphorus, and nitrate concentrations were elevated in all major tributaries during runoff, but tributaries in the south-central and eastern part of the basin produce the highest annual loading to the mainstem because of higher annual precipitation and runoff in that part of the basin. Particle-size analyses showed that most of the suspended sediment in transport consisted of silt- and clay-size material. Phosphorus enrichment was indicated throughout the mainstem by total phosphorus concentrations that ranged from 0.04 to 0.48 mg/L with a median value of 0.22 mg/L, and an interquartile range of 0.15 to 0.29 mg/L. Nitrate concentrations periodically exceeded drinking water standards in tributaries draining the south-central and eastern part of the basin. Oxygen demand was most elevated during periods of summer low flow. Correlations between levels of biochemical oxygen demand and levels of algal productivity suggest that algal biomass comprises much of the oxygen-demanding material in the mainstem. Transport of sediment, nutrients, and organic carbon within the mainstem was found to be conservative, with nearly all tributary inputs being transported downstream. Uptake and utilization of nitrate and orthophosphorus was indicated during low flow, but at normal and high flow, inputs of these constituents greatly exceeded biological utilization.

Enhanced proliferation and dopaminergic differentiation of ventral mesencephalic precursor cells by synergistic effect of FGF2 and reduced oxygen tension

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jensen, Pia; Department of Neurosurgery, University of Bern, CH-3010 Bern; Gramsbergen, Jan-Bert

Effective numerical expansion of dopaminergic precursors might overcome the limited availability of transplantable cells in replacement strategies for Parkinson's disease. Here we investigated the effect of fibroblast growth factor-2 (FGF2) and FGF8 on expansion and dopaminergic differentiation of rat embryonic ventral mesencephalic neuroblasts cultured at high (20%) and low (3%) oxygen tension. More cells incorporated bromodeoxyuridine in cultures expanded at low as compared to high oxygen tension, and after 6 days of differentiation there were significantly more neuronal cells in low than in high oxygen cultures. Low oxygen during FGF2-mediated expansion resulted also in a significant increase in tyrosine hydroxylase-immunoreactivemore » (TH-ir) dopaminergic neurons as compared to high oxygen tension, but no corresponding effect was observed for dopamine release into the culture medium. However, switching FGF2-expanded cultures from low to high oxygen tension during the last two days of differentiation significantly enhanced dopamine release and intracellular dopamine levels as compared to all other treatment groups. In addition, the short-term exposure to high oxygen enhanced in situ assessed TH enzyme activity, which may explain the elevated dopamine levels. Our findings demonstrate that modulation of oxygen tension is a recognizable factor for in vitro expansion and dopaminergic differentiation of rat embryonic midbrain precursor cells.« less

Effect of catalase inactivation on levels of inorganic peroxides, superoxide dismutase, glutathione, oxygen consumption and life span in adult houseflies (Musca domestica).

PubMed Central

Allen, R G; Farmer, K J; Sohal, R S

1983-01-01

The effects of total inhibition of catalase, induced by 3-amino-1,2,4-triazole, on the adult housefly (Musca domestica) were examined. The lack of catalase activity had no effect on the longevity of the houseflies. Inorganic-peroxide concentration was elevated at younger ages, but declined in older flies. The rate of oxygen consumption by the flies was greatly decreased and the levels of oxidized as well as reduced glutathione were augmented. Superoxide dismutase activity showed a slight increase. This study suggests that loss of catalase activity does not affect survival of houseflies due to adaptive responses. PMID:6661212

Encystment of parasitic freshwater pearl mussel (Margaritifera margaritifera) larvae coincides with increased metabolic rate and haematocrit in juvenile brown trout (Salmo trutta).

PubMed

Filipsson, Karl; Brijs, Jeroen; Näslund, Joacim; Wengström, Niklas; Adamsson, Marie; Závorka, Libor; Österling, E Martin; Höjesjö, Johan

2017-04-01

Gill parasites on fish are likely to negatively influence their host by inhibiting respiration, oxygen transport capacity and overall fitness. The glochidia larvae of the endangered freshwater pearl mussel (FPM, Margaritifera margaritifera (Linnaeus, 1758)) are obligate parasites on the gills of juvenile salmonid fish. We investigated the effects of FPM glochidia encystment on the metabolism and haematology of brown trout (Salmo trutta Linnaeus, 1758). Specifically, we measured whole-animal oxygen uptake rates at rest and following an exhaustive exercise protocol using intermittent flow-through respirometry, as well as haematocrit, in infested and uninfested trout. Glochidia encystment significantly affected whole-animal metabolic rate, as infested trout exhibited higher standard and maximum metabolic rates. Furthermore, glochidia-infested trout also had elevated levels of haematocrit. The combination of an increased metabolism and haematocrit in infested fish indicates that glochidia encystment has a physiological effect on the trout, perhaps as a compensatory response to the potential respiratory stress caused by the glochidia. When relating glochidia load to metabolism and haematocrit, fish with low numbers of encysted glochidia were the ones with particularly elevated metabolism and haematocrit. Standard metabolic rate decreased with substantial glochidia loads towards levels similar to those of uninfested fish. This suggests that initial effects visible at low levels of encystment may be countered by additional physiological effects at high loads, e.g. potential changes in energy utilization, and also that high numbers of glochidia may restrict oxygen uptake by the gills.

Oxidative stress and pathology in muscular dystrophies: focus on protein thiol oxidation and dysferlinopathies.

PubMed

Terrill, Jessica R; Radley-Crabb, Hannah G; Iwasaki, Tomohito; Lemckert, Frances A; Arthur, Peter G; Grounds, Miranda D

2013-09-01

The muscular dystrophies comprise more than 30 clinical disorders that are characterized by progressive skeletal muscle wasting and degeneration. Although the genetic basis for many of these disorders has been identified, the exact mechanism for pathogenesis generally remains unknown. It is considered that disturbed levels of reactive oxygen species (ROS) contribute to the pathology of many muscular dystrophies. Reactive oxygen species and oxidative stress may cause cellular damage by directly and irreversibly damaging macromolecules such as proteins, membrane lipids and DNA; another major cellular consequence of reactive oxygen species is the reversible modification of protein thiol side chains that may affect many aspects of molecular function. Irreversible oxidative damage of protein and lipids has been widely studied in Duchenne muscular dystrophy, and we have recently identified increased protein thiol oxidation in dystrophic muscles of the mdx mouse model for Duchenne muscular dystrophy. This review evaluates the role of elevated oxidative stress in Duchenne muscular dystrophy and other forms of muscular dystrophies, and presents new data that show significantly increased protein thiol oxidation and high levels of lipofuscin (a measure of cumulative oxidative damage) in dysferlin-deficient muscles of A/J mice at various ages. The significance of this elevated oxidative stress and high levels of reversible thiol oxidation, but minimal myofibre necrosis, is discussed in the context of the disease mechanism for dysferlinopathies, and compared with the situation for dystrophin-deficient mdx mice. © 2013 The Authors Journal compilation © 2013 FEBS.

Effect of Carbon Dioxide on the Twinkling Artifact in Ultrasound Imaging of Kidney Stones: A Pilot Study.

PubMed

Simon, Julianna C; Wang, Yak-Nam; Cunitz, Bryan W; Thiel, Jeffrey; Starr, Frank; Liu, Ziyue; Bailey, Michael R

2017-05-01

Bone demineralization, dehydration and stasis put astronauts at increased risk of forming kidney stones in space. The color-Doppler ultrasound "twinkling artifact," which highlights kidney stones with color, can make stones readily detectable with ultrasound; however, our previous results suggest twinkling is caused by microbubbles on the stone surface which could be affected by the elevated levels of carbon dioxide found on space vehicles. Four pigs were implanted with kidney stones and imaged with ultrasound while the anesthetic carrier gas oscillated between oxygen and air containing 0.8% carbon dioxide. On exposure of the pigs to 0.8% carbon dioxide, twinkling was significantly reduced after 9-25 min and recovered when the carrier gas returned to oxygen. These trends repeated when pigs were again exposed to 0.8% carbon dioxide followed by oxygen. The reduction of twinkling caused by exposure to elevated carbon dioxide may make kidney stone detection with twinkling difficult in current space vehicles. Copyright © 2016 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

Reactive oxygen species may play an essential role in driving biological evolution: The Cambrian Explosion as an example.

PubMed

Yang, Dong; Guo, Xuejun; Xie, Tian; Luo, Xiaoyan

2018-01-01

The Cambrian Explosion is one of the most significant events in the history of life; essentially all easily fossilizable animal body plans first evolved during this event. Although many theories have been proposed to explain this event, its cause remains unresolved. Here, we propose that the elevated level of oxygen, in combination with the increased mobility and food intake of metazoans, led to increased cellular levels of reactive oxygen species (ROS), which drove evolution by enhancing mutation rates and providing new regulatory mechanisms. Our hypothesis may provide a unified explanation for the Cambrian Explosion as it incorporates both environmental and developmental factors and is also consistent with ecological explanations for animal radiation. Future studies should focus on testing this hypothesis, and may lead to important insights into evolution. Copyright © 2017. Published by Elsevier B.V.

Lung development and the host response to influenza A virus are altered by different doses of neonatal oxygen in mice

PubMed Central

Buczynski, Bradley W.; Yee, Min; Paige Lawrence, B.

2012-01-01

Oxygen exposure in preterm infants has been associated with altered lung development and increased risk for respiratory viral infections later in life. Although the dose of oxygen sufficient to exert these changes in humans remains unknown, adult mice exposed to 100% oxygen between postnatal days 1–4 exhibit alveolar simplification and increased sensitivity to influenza virus infection. Additionally, two nonlinear thresholds of neonatal oxygen exposures were previously identified that promote modest (between 40% and 60% oxygen) and severe (between 80% and 100% oxygen) changes in lung development. Here, we investigate whether these two thresholds correlate with the severity of lung disease following respiratory viral infection. Adult mice exposed to 100% oxygen at birth, and to a lesser extent 80% oxygen, demonstrated enhanced body weight loss, persistent inflammation, and fibrosis following infection compared with infected siblings exposed to room air at birth. In contrast, the host response to infection was indistinguishable between mice exposed to room air and 40% or 60% oxygen. Interestingly, levels of monocyte chemoattractant protein (MCP)-1 were equivalently elevated in infected mice that had been exposed to 80% or 100% oxygen as neonates. However, reducing levels of MCP-1 using heterozygous Mcp-1 mice did not affect oxygen-dependent changes in the response to infection. Thus lung development and the host response to respiratory viral infection are disrupted by different doses of oxygen. Our findings suggest that measuring lung function alone may not be sufficient to identify individuals born prematurely who have increased risk for respiratory viral infection. PMID:22408042

Reduction of blood oxygen levels enhances postprandial cardiac hypertrophy in Burmese python (Python bivittatus).

PubMed

Slay, Christopher E; Enok, Sanne; Hicks, James W; Wang, Tobias

2014-05-15

Physiological cardiac hypertrophy is characterized by reversible enlargement of cardiomyocytes and changes in chamber architecture, which increase stroke volume and via augmented convective oxygen transport. Cardiac hypertrophy is known to occur in response to repeated elevations of O2 demand and/or reduced O2 supply in several species of vertebrate ectotherms, including postprandial Burmese pythons (Python bivittatus). Recent data suggest postprandial cardiac hypertrophy in P. bivittatus is a facultative rather than obligatory response to digestion, though the triggers of this response are unknown. Here, we hypothesized that an O2 supply-demand mismatch stimulates postprandial cardiac enlargement in Burmese pythons. To test this hypothesis, we rendered animals anemic prior to feeding, essentially halving blood oxygen content during the postprandial period. Fed anemic animals had heart rates 126% higher than those of fasted controls, which, coupled with a 71% increase in mean arterial pressure, suggests fed anemic animals were experiencing significantly elevated cardiac work. We found significant cardiac hypertrophy in fed anemic animals, which exhibited ventricles 39% larger than those of fasted controls and 28% larger than in fed controls. These findings support our hypothesis that those animals with a greater magnitude of O2 supply-demand mismatch exhibit the largest hearts. The 'low O2 signal' stimulating postprandial cardiac hypertrophy is likely mediated by elevated ventricular wall stress associated with postprandial hemodynamics. © 2014. Published by The Company of Biologists Ltd.

Simultaneously multiparametric spectroscopic monitoring of tissue viability in the brain and small intestine

NASA Astrophysics Data System (ADS)

Tolmasov, Michael; Barbiro-Michaely, Efrat; Mayevsky, Avraham

2007-02-01

Under body O II imbalance, the Autonomic Nervous System is responsible for redistribution of blood flow with preference to the most vital organs (brain, heart), while the less vital organs (intestine, GI tract) are hypoperfused. The aim of this study was to develop and use an animal model for real time monitoring of tissue viability in the brain, and the small intestine, under various levels of oxygen and blood supply. Male Wistar rats were anesthetized, the brain cortex and intestinal serosa were exposed and connected by optical fibers to the Multi-Site Multi-Parametric (MSMP) monitoring system. Tissue blood flow (TBF) and mitochondrial NADH redox state were monitored simultaneously in the two organs. The rats were subjected to short anoxia, 20 minutes hypoxia or epinephrine (2& 8μg/kg I.V.). Under oxygen deficiency, cerebral blood flow (CBF) was elevated, whereas intestinal TBF was reduced. Mitochondrial NADH was significantly elevated in both organs. Systemic injection of Adrenaline showed a dose-depended increase in systemic blood pressure and CBF response whereas, intestinal TBF similarly decreased in both doses. In addition, NADH was elevated (reduced form) in the intestine whereas oxidation was observed in the brain. In conclusion, our preliminary results may imply the ability of using of the MSMP for monitoring non-vital organs in order to detect early changes in the balance between oxygen supply and demand in the body.

Static feed water electrolysis subsystem development

NASA Technical Reports Server (NTRS)

Schubert, Franz H. (Inventor); Grigger, David J. (Inventor)

1991-01-01

This disclosure is directed to an electrolysis cell forming hydrogen and oxygen at spaced terminals. The anode terminal is porous and able to form oxygen within the cell and permit escape of the gaseous oxygen through the anode and out through a flow line in the presence of backpressure. Hydrogen is liberated in the cell at the opposing solid metal cathode which is permeable to hydrogen but not oxygen so that the migratory hydrogen formed in the cell is able to escape from the cell. The cell is maintained at an elevated pressure so that oxygen liberated by the cell is delivered at elevated pressure without pumping to raise the pressure of the oxygen.

Effect of Prolonged Exposure to Elevated Carbon Monoxide and Carbon Dioxide Levels on Red Blood Cell Parameters during Submarine Patrols

DTIC Science & Technology

1975-12-01

rise in Hb, Hct. and red cells, to compensate for the anoxic stress induced by higher carboxyhemoglobin levels (HbCO). Inhalation of CO2 in higher...expected to cause an equilibrium value of 8-50% carboxyhemoglobin (HbCO). Under these conditions, Schulte (1961) did not find any gross changes in...according to Stewart (1974). Carboxyhemoglobin levels of 1-5% cause an increased blood Cow to vital organs, which compensates for the loss of oxygen

Photoacoustic microscopy of cerebral hemodynamic and oxygen-metabolic responses to anesthetics

NASA Astrophysics Data System (ADS)

Cao, Rui; Li, Jun; Ning, Bo; Sun, Naidi; Wang, Tianxiong; Zuo, Zhiyi; Hu, Song

2017-02-01

General anesthetics are known to have profound effects on cerebral hemodynamics and neuronal activities. However, it remains a challenge to directly assess anesthetics-induced hemodynamic and oxygen-metabolic changes from the true baseline under wakefulness at the microscopic level, due to the lack of an enabling technology for high-resolution functional imaging of the awake mouse brain. To address this challenge, we have developed head-restrained photoacoustic microscopy (PAM), which enables simultaneous imaging of the cerebrovascular anatomy, total concentration and oxygen saturation of hemoglobin (CHb and sO2), and blood flow in awake mice. From these hemodynamic measurements, two important metabolic parameters, oxygen extraction fraction (OEF) and the cerebral metabolic rate of oxygen (CMRO2), can be derived. Side-by-side comparison of the mouse brain under wakefulness and anesthesia revealed multifaceted cerebral responses to isoflurane, a volatile anesthetic widely used in preclinical research and clinical practice. Key observations include elevated cerebral blood flow (CBF) and reduced oxygen extraction and metabolism.

Increased capillaries in mitochondrial myopathy: implications for the regulation of oxygen delivery.

PubMed

Taivassalo, Tanja; Ayyad, Karen; Haller, Ronald G

2012-01-01

Human skeletal muscle respiratory chain defects restrict the ability of working muscle to extract oxygen from blood, and result in a hyperkinetic circulation during exercise in which oxygen delivery is excessive relative to oxygen uptake and oxygen levels within contracting muscle are abnormally high. To investigate the role of the muscle microcirculation in this anomalous circulatory response and possible implications for the regulation of muscle angiogenesis, we assessed muscle oxidative capacity during cycle exercise and determined capillary levels and distribution and vascular endothelial growth factor expression in quadriceps muscle biopsies in patients with mitochondrial myopathy attributable to heteroplasmic mitochondrial DNA mutations. We found that in patients with mitochondrial myopathy, muscle capillary levels were twice that of sedentary healthy subjects (3.0 ± 0.9% compared with 1.4 ± 0.3%, P < 0.001) despite the fact that oxygen utilization during peak cycle exercise was half that of control subjects (11.1 ± 4.0 ml/kg/min compared with 20.7 ± 7.9 ml/kg/min, P < 0.01); that capillary area was greatest in patients with the most severe muscle oxidative defects and was more than two times higher around muscle fibre segments with defective (i.e. cytochrome oxidase negative/succinic dehydrogenase-positive or 'ragged-red' fibres) compared with more preserved respiratory chain function; and that vascular endothelial growth factor expression paralleled capillary distribution. The increased muscle capillary levels in patients correlated directly (r(2) = 0.68, P < 0.05) with the severity of the mismatch between systemic oxygen delivery (cardiac output) and oxygen utilization during cycle exercise. Our results suggest that capillary growth is increased as a result of impaired muscle oxidative phosphorylation in mitochondrial myopathy, thus promoting increased blood flow to respiration-incompetent muscle fibres and a mismatch between oxygen delivery and utilization during exercise. Furthermore, the finding of high capillary levels despite elevated tissue oxygen levels during exercise in respiration-deficient muscle fibres implies that mitochondrial metabolism activates angiogenesis in skeletal muscle by a mechanism that is independent of hypoxia.

Production of recombinant protein by a novel oxygen-induced system in Escherichia coli.

PubMed

Baez, Antonino; Majdalani, Nadim; Shiloach, Joseph

2014-04-07

The SoxRS regulon of E. coli is activated in response to elevated dissolved oxygen concentration likely to protect the bacteria from possible oxygen damage. The soxS expression can be increased up to 16 fold, making it a possible candidate for recombinant protein expression. Compared with the existing induction approaches, oxygen induction is advantageous because it does not involve addition or depletion of growth factors or nutrients, addition of chemical inducers or temperature changes that can affect growth and metabolism of the producing bacteria. It also does not affect the composition of the growth medium simplifying the recovery and purification processes. The soxS promoter was cloned into the commercial pGFPmut3.1 plasmid creating pAB49, an expression vector that can be induced by increasing oxygen concentration. The efficiency and the regulatory properties of the soxS promoter were characterized by measuring the GFP expression when the culture dissolved oxygen concentration was increased from 30% to 300% air saturation. The expression level of recombinant GFP was proportional to the oxygen concentration, demonstrating that pAB49 is a controllable expression vector. A possible harmful effect of elevated oxygen concentration on the recombinant product was found to be negligible by determining the protein-carbonyl content and its specific fluorescence. By performing high density growth in modified LB medium, the cells were induced by increasing the oxygen concentration. After 3 hours at 300% air saturation, GFP fluorescence reached 109000 FU (494 mg of GFP/L), representing 3.4% of total protein, and the cell concentration reached 29.1 g/L (DW). Induction of recombinant protein expression by increasing the dissolved oxygen concentration was found to be a simple and efficient alternative expression strategy that excludes the use of chemical, nutrient or thermal inducers that have a potential negative effect on cell growth or the product recovery.

Evaluating optimal superficial limb perfusion at different angles using non-invasive micro-lightguide spectrophotometry.

PubMed

Darmanin, Geraldine; Jaggard, Matthew; Hettiaratchy, Shehan; Nanchahal, Jagdeep; Jain, Abhilash

2013-06-01

It is common practice to elevate the limbs postoperatively to reduce oedema and hence optimise perfusion and facilitate rehabilitation. However, elevation may be counterproductive as it reduces the mean perfusion pressure. There are no clear data on the optimal position of the limbs even in normal subjects. The optimal position of limbs was investigated in 25 healthy subjects using a non-invasive micro-lightguide spectrophotometry system "O2C", which indirectly measures skin and superficial tissue perfusion through blood flow, oxygen saturation and relative haemoglobin concentration. We found a reduction in skin and superficial tissue blood flow of 17% (p=0.0001) on arm elevation (180° shoulder flexion) as compared to heart level and an increase in skin and superficial tissue blood flow of 25% (p=0.02) on forearm elevation of 45°. Lower limb skin and superficial tissue blood flow decreased by 15% (p=0.004) on elevation to 47 cm and by 70% on dependency (p=0.0001) compared to heart level. However, on elevation of the lower limb there was also a 28% reduction in superficial venous pooling (p=0.0001) compared to heart level. In the normal limb, the position for optimal superficial perfusion of the upper limb is with the arm placed at heart level and forearm at 45°. In the lower limb the optimal position for superficial perfusion would be at heart level. However, some degree of elevation may be useful if there is an element of venous congestion. Copyright © 2013 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

Mitochondrial DNA Markers Reveal High Genetic Diversity but Low Genetic Differentiation in the Black Fly Simulium tani Takaoka & Davies along an Elevational Gradient in Malaysia

PubMed Central

Low, Van Lun; Adler, Peter H.; Takaoka, Hiroyuki; Ya’cob, Zubaidah; Lim, Phaik Eem; Tan, Tiong Kai; Lim, Yvonne A. L.; Chen, Chee Dhang; Norma-Rashid, Yusoff; Sofian-Azirun, Mohd

2014-01-01

The population genetic structure of Simulium tani was inferred from mitochondria-encoded sequences of cytochrome c oxidase subunits I (COI) and II (COII) along an elevational gradient in Cameron Highlands, Malaysia. A statistical parsimony network of 71 individuals revealed 71 haplotypes in the COI gene and 43 haplotypes in the COII gene; the concatenated sequences of the COI and COII genes revealed 71 haplotypes. High levels of genetic diversity but low levels of genetic differentiation were observed among populations of S. tani at five elevations. The degree of genetic diversity, however, was not in accordance with an altitudinal gradient, and a Mantel test indicated that elevation did not have a limiting effect on gene flow. No ancestral haplotype of S. tani was found among the populations. Pupae with unique structural characters at the highest elevation showed a tendency to form their own haplotype cluster, as revealed by the COII gene. Tajima’s D, Fu’s Fs, and mismatch distribution tests revealed population expansion of S. tani in Cameron Highlands. A strong correlation was found between nucleotide diversity and the levels of dissolved oxygen in the streams where S. tani was collected. PMID:24941043

Simulation of hydrodynamics, temperature, and dissolved oxygen in Beaver Lake, Arkansas, 1994-1995

USGS Publications Warehouse

Haggard, Brian; Green, W. Reed

2002-01-01

The tailwaters of Beaver Lake and other White River reservoirs support a cold-water trout fishery of significant economic yield in northwestern Arkansas. The Arkansas Game and Fish Commission has requested an increase in existing minimum flows through the Beaver Lake dam to increase the amount of fishable waters downstream. Information is needed to assess the impact of additional minimum flows on temperature and dissolved-oxygen qualities of reservoir water above the dam and the release water. A two-dimensional, laterally averaged hydrodynamic, thermal and dissolved-oxygen model was developed and calibrated for Beaver Lake, Arkansas. The model simulates surface-water elevation, currents, heat transport and dissolved-oxygen dynamics. The model was developed to assess the impacts of proposed increases in minimum flows from 1.76 cubic meters per second (the existing minimum flow) to 3.85 cubic meters per second (the additional minimum flow). Simulations included assessing (1) the impact of additional minimum flows on tailwater temperature and dissolved-oxygen quality and (2) increasing initial water-surface elevation 0.5 meter and assessing the impact of additional minimum flow on tailwater temperatures and dissolved-oxygen concentrations. The additional minimum flow simulation (without increasing initial pool elevation) appeared to increase the water temperature (<0.9 degrees Celsius) and decrease dissolved oxygen concentration (<2.2 milligrams per liter) in the outflow discharge. Conversely, the additional minimum flow plus initial increase in pool elevation (0.5 meter) simulation appeared to decrease outflow water temperature (0.5 degrees Celsius) and increase dissolved oxygen concentration (<1.2 milligrams per liter) through time. However, results from both minimum flow scenarios for both water temperature and dissolved oxygen concentration were within the boundaries or similar to the error between measured and simulated water column profile values.

The Effects of Elevated pCO2, Hypoxia and Temperature on Larval Sheepshead minnow, Cyprinodon variegatus: How much stress is too much?

EPA Science Inventory

Estuarine fish are acclimated to living in an environment with rapid and frequent changes in temperature, salinity, pH, and dissolved oxygen (DO) levels; the physiology of these organisms is well suited to cope with extreme thermal, hypercapnic, and hypoxic stress. While the adve...

Oxygen Candle Background for Subs and Space

NASA Technical Reports Server (NTRS)

Graf, John

2017-01-01

"At any time and without warning, a submarine may have to remain submerged for several days on account of the presence of the enemy, or rough weather, or serious accident to the machinery. Fortunately such occurrences are rare; but every commanding officer must be prepared to meet such an emergency that will afford his men the greatest possible chance of survival." Reference (1) This quotation is taken from a review of submarine air purification technology published by the Bureau of Medicine and Surgery in 1919. At that time, the U.S. Navy had just begun to experiment with possible air purification devices and supplies of oxygen that might permit submarines to remain submerged longer that the untreated closed atmosphere would allow. Submariners were exposed to elevated levels of carbon dioxide and reduced levels of oxygen that would be considered completely unacceptable by current standards. It was a different world, but humans are still humans, and the requirements for safe and effective functioning in a self-contained environment are really unchanged. The maximum submergence time for submarines as published in that work was approximately 48 hours, reference (1) In early submarines, the preferred supply of oxygen was 1800 psig compressed gas bled into the boat as needed, references (1,2). The need for added oxygen was occasionally "measured" by the physiological impact on the crew rather than a reliable instrument, reference (1). The design of submarine oxygen supply was limited to approximately 25 day submerged operation, reference (2). It was not until 1958 that U.S. submarines were able to carry out dives beyond that period and necessitated new sources of oxygen, reference (2). A curious second source of oxygen at the time was compressed air vessels that were bled into the boat while "vitiated" air (air with reduced oxygen and elevated carbon dioxide) from the opposite end of the boat was compressed into waiting empty vessels, reference (1). The periodic use of pressurized air to control oxygen caused swings in ambient pressure that was uncomfortable to the crew, reference (1). As early as 1919, liquid oxygen was a commercially available product and its use on submarines was contemplated, reference (1). It is interesting that even at this date, 1919, the danger of oils or greases when exposed to compressed or liquid oxygen was recognized: "One precaution must be always taken. No oil or grease should be used in the gauge or fittings or a dangerous explosion may result."

3-Mercaptopyruvate Sulfurtransferase, Not Cystathionine β-Synthase Nor Cystathionine γ-Lyase, Mediates Hypoxia-Induced Migration of Vascular Endothelial Cells.

PubMed

Tao, Beibei; Wang, Rui; Sun, Chen; Zhu, Yichun

2017-01-01

Hypoxia-induced angiogenesis is a common phenomenon in many physiological and patho-physiological processes. However, the potential differential roles of three hydrogen sulfide producing systems cystathionine γ-lyase (CSE)/H 2 S, cystathionine β-synthase (CBS)/H 2 S, and 3-mercaptopyruvate sulfurtransferase (MPST)/H 2 S in hypoxia-induced angiogenesis are still unknown. We found that minor hypoxia (10% oxygen) significantly increased the migration of vascular endothelial cells while hypoxia (8% oxygen) significantly inhibited cell migration. The present study was performed using cells cultured in 10% oxygen. RNA interference was used to block the endogenous generation of hydrogen sulfide by CSE, CBS, or MPST in a vascular endothelial cell migration model in both normoxia and hypoxia. The results showed that CBS had a promoting effect on the migration of vascular endothelial cells cultured in both normoxic and hypoxic conditions. In contrast, CSE had an inhibitory effect on cell migration. MPST had a promoting effect on the migration of vascular endothelial cells cultured in hypoxia; however, it had no effect on the cells cultured in normoxia. Importantly, it was found that the hypoxia-induced increase in vascular endothelial cell migration was mediated by MPST, but not CSE or CBS. The western blot analyses showed that hypoxia significantly increased MPST protein levels, decreased CSE protein levels and did not change CBS levels, suggesting that these three hydrogen sulfide-producing systems respond differently to hypoxic conditions. Interestingly, MPST protein levels were elevated by hypoxia in a bi-phasic manner and MPST mRNA levels increased later than the first stage elevation of the protein levels, implying that the expression of MPST induced by hypoxia was also regulated at a post-transcriptional level. RNA pull-down assay showed that some candidate RNA binding proteins, such as nucleolin and Annexin A2, were dissociated from the 3'-UTR of MPST mRNA in hypoxia which implied their involvement in MPST mRNA regulation.

Sympathetic neural overactivity in healthy humans after prolonged exposure to hypobaric hypoxia

PubMed Central

Hansen, Jim; Sander, Mikael

2003-01-01

Acute exposure to hypoxia causes chemoreflex activation of the sympathetic nervous system. During acclimatization to high altitude hypoxia, arterial oxygen content recovers, but it is unknown to what degree sympathetic activation is maintained or normalized during prolonged exposure to hypoxia. We therefore measured sympathetic nerve activity directly by peroneal microneurography in eight healthy volunteers (24 ± 2 years of age) after 4 weeks at an altitude of 5260 m (Chacaltaya, Bolivian Andes) and at sea level (Copenhagen). The subjects acclimatized well to altitude, but in every subject sympathetic nerve activity was highly elevated at altitude vs. sea level (48 ± 5 vs. 16 ± 3 bursts min−1, respectively, P < 0.05), coinciding with increased mean arterial blood pressure (87 ± 3 vs. 77 ± 2 mmHg, respectively, P < 0.05). To examine the underlying mechanisms, we administered oxygen (to eliminate chemoreflex activation) and saline (to reduce cardiopulmonary baroreflex deactivation). These interventions had minor effects on sympathetic activity (48 ± 5 vs. 38 ± 4 bursts min−1, control vs. oxygen + saline, respectively, P < 0.05). Moreover, sympathetic activity was still markedly elevated (37 ± 5 bursts min−1) when subjects were re-studied under normobaric, normoxic and hypervolaemic conditions 3 days after return to sea level. In conclusion, acclimatization to high altitude hypoxia is accompanied by a striking and long-lasting sympathetic overactivity. Surprisingly, chemoreflex activation by hypoxia and baroreflex deactivation by dehydration together could account for only a small part of this response, leaving the major underlying mechanisms unexplained. PMID:12563015

Oxidative Stress Markers Correlate with Renal Dysfunction and Thrombocytopenia in Severe Leptospirosis

PubMed Central

Araújo, Alan M.; Reis, Eliana A. G.; Athanazio, Daniel A.; Ribeiro, Guilherme S.; Hagan, José E.; Araujo, Guilherme C.; Damião, Alcineia O.; Couto, Nicolli S.; Ko, Albert I.; Noronha-Dutra, Alberto; Reis, Mitermayer G.

2014-01-01

Leptospirosis is a zoonotic disease that causes severe manifestations such as Weil's disease and pulmonary hemorrhage syndrome. The aim of this study was to evaluate whether reactive oxygen species (ROS) production and antioxidant reduced glutathione (GSH) levels are related to complications in patients hospitalized with leptospirosis. The ROS production and GSH levels were measured in blood samples of 12 patients and nine healthy controls using chemiluminescence and absorbance assays. We found that ROS production was higher and GSH levels were lower in leptospirosis patients compared with healthy individuals. Among patients, GSH depletion was correlated with thrombocytopenia and elevated serum creatinine, whereas a strong positive correlation was observed between ROS production and elevated serum potassium. Additional investigation of the biological significance of ROS production and GSH levels is warranted as they may guide the development of novel adjuvant therapies for leptospirosis targeting oxidative stress. PMID:24493675

Water quality and processes affecting dissolved oxygen concentrations in the Blackwater River, Canaan Valley, West Virginia

USGS Publications Warehouse

Waldron, M.C.; Wiley, J.B.

1996-01-01

The water quality and environmental processes affecting dissolved oxygen were determined for the Blackwater River in Canaan Valley, West Virginia. Canaan Valley is oval-shaped (14 miles by 5 miles) and is located in the Allegheny Mountains at an average elevation of 3,200 feet above sea level. Tourism, population, and real estate development have increased in the past two decades. Most streams in Canaan Valley are a dilute calcium magnesium bicarbonate-type water. Streamwater typicaly was soft and low in alkalinity and dissolved solids. Maximum values for specific conductance, hardness, alkalinity, and dissolved solids occurred during low-flow periods when streamflow was at or near baseflow. Dissolved oxygen concentrations are most sensitive to processes affecting the rate of reaeration. The reaeration is affected by solubility (atmospheric pressure, water temperature, humidity, and cloud cover) and processes that determine stream turbulence (stream depth, width, velocity, and roughness). In the headwaters, photosynthetic dissolved oxygen production by benthic algae can result in supersaturated dissolved oxygen concentrations. In beaver pools, dissolved oxygen consumption from sediment oxygen demand and carbonaceous biochemical oxygen demand can result in dissolved oxygen deficits.

The effects of arterial carbon dioxide partial pressure and sevoflurane on capillary venous cerebral blood flow and oxygen saturation during craniotomy.

PubMed

Klein, Klaus Ulrich; Glaser, Martin; Reisch, Robert; Tresch, Achim; Werner, Christian; Engelhard, Kristin

2009-07-01

Intraoperative routine monitoring of cerebral blood flow and oxygenation remains a technological challenge. Using the physiological principle of carbon dioxide reactivity of cerebral vasculature, we investigated a recently developed neuromonitoring device (oxygen-to-see, O2C device) for simultaneous measurements of regional cerebral blood flow (rvCBF), blood flow velocity (rvVelo), oxygen saturation (srvO2), and hemoglobin amount (rvHb) at the capillary venous level in patients subjected to craniotomy. Twenty-six neurosurgical patients were randomly assigned to anesthesia with 1.4% or 2.0% sevoflurane end-tidal concentration. After craniotomy, a fiberoptic probe was applied on a macroscopically healthy surface of cerebral tissue next to the site of surgery. Simultaneous measurements in 2 and 8 mm cerebral depth were performed in each patient during lower (35 mm Hg) and higher (45 mm Hg) levels (random order) of arterial carbon dioxide partial pressure (PaCO2). The principle of these measurements relies on the combination of laser-Doppler flowmetry (rvCBF, rvVelo) and photo-spectrometry (srvO2, rvHb). Linear models were fitted to test changes of end points (rvCBF, rvVelo, srvO2, rvHb) in response to lower and higher levels of PaCO2, 1.4% and 2.0% sevoflurane end-tidal concentration, and 2 and 8 mm cerebral depth. RvCBF and rvVelo were elevated by PaCO2 independent of sevoflurane concentration in 2 and 8 mm depth of cerebral tissue (P < 0.001). Higher PaCO2 induced an increase in mean srvO2 from 50% to 68% (P < 0.001). RvVelo (P < 0.001) and srvO2 (P = 0.007) were higher in 8 compared with 2 mm cerebral depth. RvHb was not influenced by alterations in PaCO2 but positively correlated to sevoflurane concentration (P = 0.005). Increases in rvCBF and rvVelo by PaCO2 suggest preserved hypercapnic vasodilation under anesthesia with sevoflurane 1.4% and 2.0% end-tidal concentration. A consecutive increase in srvO2 implies that cerebral arteriovenous difference in oxygen was decreased by elevated PaCO2. Unchanged levels of rvHb signify that there was no blood loss during measurements. Data suggest that the device allows detection of local changes in blood flow and oxygen saturation in response to different PaCO2 levels in predominant venous cerebral microvessels.

Reactive oxygen species triggering systemic programmed cell death process via elevation of nuclear calcium ion level in tomatoes resisting tobacco mosaic virus.

PubMed

Li, Yang; Li, Qi; Hong, Qiang; Lin, Yichun; Mao, Wang; Zhou, Shumin

2018-05-01

Programmed cell death (PCD) plays a positive role in the systemic response of plants to pathogen resistance. It has been confirmed that local tobacco mosaic virus (TMV) infecting tomato leaves can induce systemic PCD process in root-tip tissues. But up to now the underlying physiological mechanisms are poorly understood. This study focused on the detailed investigation of the physiological responses of root-tip cells during the initiation of systemic PCD. Physiological, biochemical examination and cytological observation showed that 1 day post-inoculation (dpi) of TMV inoculation there was an increase in calcium fluorescence intensity in root tip tissue cells. Then at 2 dpi, 4 dpi, 8 dpi and 15 dpi, the fluorescence intensity of calcium ion continued to increase. However, at 5 dpi, the reactive oxygen species (ROS) began to accumulate in the root-tip cells. And finally at 20 dpi, the obvious PCD reaction was detected. In addition, the experimental results also showed that the above process involved the elevation of two types of intracellular Ca 2+ , including cytoplasmic calcium ([Ca 2+ ] cyt ) and nuclear calcium ([Ca 2+ ] nuc ). The [Ca 2+ ] cyt , as a pilot signal could lead to the subsequent elevation of intracellular ROS concentration. Then, the high levels of ROS stimulated an increase of [Ca 2+ ] nuc and eventually caused PCD reactions in the root-tip tissues. In particular, the high level of nuclear calcium is an essential mediator in systemic PCD of plants. Copyright © 2018 Elsevier B.V. All rights reserved.

In-situ restoration of one-stage partial nitritation-anammox process deteriorated by nitrate build-up via elevated substrate levels

PubMed Central

Wang, Xiaolong; Gao, Dawen

2016-01-01

The one-stage partial nitritation and anammox process (PN/A) has been a promising microbial process to remove ammonia from wastewater especially with low carbon/nitrogen ratio. The main breakdown was the deterioration caused by overgrowth of nitrite oxidizing bacteria (NOB) resulting effluent nitrate build-up in the PN/A process. This study presented an in-situ restoring strategy for suppressing NOB activity in a one-stage granular PN/A system deteriorated over 2 months, using elevated concentrations of substrates (ammonia and nitrite) under limited dissolved oxygen level. The results showed that the NOB activity was successfully suppressed after 56 days of restoration, and finally the ratio of produced nitrate/consumed ammonium was reduced from 36.8% to 7%. On day 66 the nitrogen removal rate obtained as 1.2 kg N/(m3·d). The high FA level (5–40 mg/L) and low dissolved oxygen (<0.13 mg/L) were responsible for NOB suppression. From quantitative PCR (qPCR) analysis, after this restoration, anammox bacteria had a widely growth, and AOB stay stable, but Nitrospira increase and Nitrobacter declined. High amount of NOB was still persistent in the granules, which was not easy to wash-out and threaten the deammonification performance. PMID:27881860

Response of sediment microbial community structure in a freshwater reservoir to manipulations in oxygen availability.

PubMed

Bryant, Lee D; Little, John C; Bürgmann, Helmut

2012-04-01

Hypolimnetic oxygenation systems (HOx) are being increasingly used in freshwater reservoirs to elevate dissolved oxygen levels in the hypolimnion and suppress sediment-water fluxes of soluble metals (e.g. Fe and Mn) which are often microbially mediated. We assessed changes in sediment microbial community structure and corresponding biogeochemical cycling on a reservoir-wide scale as a function of HOx operations. Sediment microbial biomass as quantified by DNA concentration was increased in regions most influenced by the HOx. Following an initial decrease in biomass in the upper sediment while oxygen concentrations were low, biomass typically increased at all depths as the 4-month-long oxygenation season progressed. A distinct shift in microbial community structure was only observed at the end of the season in the upper sediment near the HOx. While this shift was correlated to HOx-enhanced oxygen availability, increased TOC levels and precipitation of Fe- and Mn-oxides, abiotic controls on Fe and Mn cycling, and/or the adaptability of many bacteria to variations in prevailing electron acceptors may explain the delayed response and the comparatively limited changes at other locations. While the sediment microbial community proved remarkably resistant to relatively short-term changes in HOx operations, HOx-induced variation in microbial structure, biomass, and activity was observed after a full season of oxygenation. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

Genetic Diversity of Coastal Bottlenose Dolphins Revealed by Structurally and Functionally Diverse Hemoglobins

PubMed Central

Remington, Nicole; Stevens, Robert D.; Wells, Randall S.; Hohn, Aleta; Dhungana, Suraj; Taboy, Celine H.; Crumbliss, Alvin L.; Henkens, Robert; Bonaventura, Celia

2007-01-01

Studies of structure-function relationships in the respiratory proteins of marine mammals revealed unexpected variations in the number and types of hemoglobins (Hbs) present in coastal bottlenose dolphins, Tursiops truncatus. We obtained blood samples from free-ranging coastal bottlenose dolphins as a component of capture-release studies. We found that the oxygen-binding functions of bottlenose dolphin blood are poised between effector-saturated and unsaturated levels, enabling exercise-dependent shifts in oxygen transfer functions. Isolated bottlenose dolphin Hbs showed elevated pH sensitivities (Bohr effects) and appreciably lower oxygen affinities than adult human Hb in the absence of allosteric effectors. These properties may be an adaptive modification that enhance oxygen delivery during diving episodes when oxygen tensions and effector levels are low. The Hbs of individual dolphins showed similar oxygen affinities, responses to effectors, and expression of heme-heme interaction in oxygen binding, but differed in their redox potentials and rates of autoxidation. The heterogeneity suggested by these functional variations in Hbs of individual dolphins was born out by variations in the molecular weights and numbers of their α and β globin chains. Although coastal bottlenose dolphins were expected to have a single type of Hb, the mass differences observed revealed considerable genetic diversity. There were multiple Hb forms in some individuals and differences in Hb patterns among individuals within the same community. PMID:17604574

Genetic diversity of coastal bottlenose dolphins revealed by structurally and functionally diverse hemoglobins.

PubMed

Remington, Nicole; Stevens, Robert D; Wells, Randall S; Holn, Aleta; Dhungana, Suraj; Taboy, Celine H; Crumbliss, Alvin L; Henkens, Robert; Bonaventura, Celia

2007-08-15

Studies of structure-function relationships in the respiratory proteins of marine mammals revealed unexpected variations in the number and types of hemoglobins (Hbs) present in coastal bottlenose dolphins, Tursiops truncatus. We obtained blood samples from free-ranging coastal bottlenose dolphins as a component of capture-release studies. We found that the oxygen-binding functions of bottlenose dolphin blood are poised between effector-saturated and unsaturated levels, enabling exercise-dependent shifts in oxygen transfer functions. Isolated bottlenose dolphin Hbs showed elevated pH sensitivities (Bohr effects) and appreciably lower oxygen affinities than adult human Hb in the absence of allosteric effectors. These properties may be an adaptive modification that enhances oxygen delivery during diving episodes when oxygen tensions and effector levels are low. The Hbs of individual dolphins showed similar oxygen affinities, responses to effectors, and expression of heme-heme interaction in oxygen binding, but differed in their redox potentials and rates of autoxidation. The heterogeneity suggested by these functional variations in Hbs of individual dolphins was born out by variations in the molecular weights and numbers of their alpha and beta globin chains. Although coastal bottlenose dolphins were expected to have a single type of Hb, the mass differences observed revealed considerable genetic diversity. There were multiple Hb forms in some individuals and differences in Hb patterns among individuals within the same community.

Linear and non-linear contributions to oxygen transport and utilization during moderate random exercise in humans.

PubMed

Beltrame, T; Hughson, R L

2017-05-01

What is the central question of this study? The pulmonary oxygen uptake (pV̇O2) data used to study the muscle aerobic system dynamics during moderate-exercise transitions is classically described as a mono-exponential function controlled by a complex interaction of the oxygen delivery-utilization balance. This elevated complexity complicates the acquisition of relevant information regarding aerobic system dynamics based on pV̇O2 data during a varying exercise stimulus. What is the main finding and its importance? The elevated complexity of pV̇O2 dynamics is a consequence of a multiple-order interaction between muscle oxygen uptake and circulatory distortion. Our findings challenge the use of a first-order function to study the influences of the oxygen delivery-utilization balance over the pV̇O2 dynamics. The assumption of aerobic system linearity implies that the pulmonary oxygen uptake (pV̇O2) dynamics during exercise transitions present a first-order characteristic. The main objective of this study was to test the linearity of the oxygen delivery-utilization balance during random moderate exercise. The cardiac output (Q̇) and deoxygenated haemoglobin concentration ([HHb]) were measured to infer the central and local O 2 availability, respectively. Thirteen healthy men performed two consecutive pseudorandom binary sequence cycling exercises followed by an incremental protocol. The system input and the outputs pV̇O2, [HHb] and Q̇ were submitted to frequency-domain analysis. The linearity of the variables was tested by computing the ability of the response at a specific frequency to predict the response at another frequency. The predictability levels were assessed by the coefficient of determination. In a first-order system, a participant who presents faster dynamics at a specific frequency should also present faster dynamics at any other frequency. All experimentally obtained variables (pV̇O2, [HHb] and Q̇) presented a certainly degree of non-linearity. The local O 2 availability, evaluated by the ratio pV̇O2/[HHb], presented the most irregular behaviour. The overall [HHb] kinetics were faster than pV̇O2 and Q̇ kinetics. In conclusion, the oxygen delivery-utilization balance behaved as a non-linear phenomenon. Therefore, the elevated complexity of the pulmonary oxygen uptake dynamics is governed by a complex multiple-order interaction between the oxygen delivery and utilization systems. © 2017 The Authors. Experimental Physiology © 2017 The Physiological Society.

Oxygen as a driver of early arthropod micro-benthos evolution.

PubMed

Williams, Mark; Vannier, Jean; Corbari, Laure; Massabuau, Jean-Charles

2011-01-01

We examine the physiological and lifestyle adaptations which facilitated the emergence of ostracods as the numerically dominant Phanerozoic bivalve arthropod micro-benthos. The PO(2) of modern normoxic seawater is 21 kPa (air-equilibrated water), a level that would cause cellular damage if found in the tissues of ostracods and much other marine fauna. The PO(2) of most aquatic breathers at the cellular level is much lower, between 1 and 3 kPa. Ostracods avoid oxygen toxicity by migrating to waters which are hypoxic, or by developing metabolisms which generate high consumption of O(2). Interrogation of the Cambrian record of bivalve arthropod micro-benthos suggests a strong control on ecosystem evolution exerted by changing seawater O(2) levels. The PO(2) of air-equilibrated Cambrian-seawater is predicted to have varied between 10 and 30 kPa. Three groups of marine shelf-dwelling bivalve arthropods adopted different responses to Cambrian seawater O(2). Bradoriida evolved cardiovascular systems that favoured colonization of oxygenated marine waters. Their biodiversity declined during intervals associated with black shale deposition and marine shelf anoxia and their diversity may also have been curtailed by elevated late Cambrian (Furongian) oxygen-levels that increased the PO(2) gradient between seawater and bradoriid tissues. Phosphatocopida responded to Cambrian anoxia differently, reaching their peak during widespread seabed dysoxia of the SPICE event. They lacked a cardiovascular system and appear to have been adapted to seawater hypoxia. As latest Cambrian marine shelf waters became well oxygenated, phosphatocopids went extinct. Changing seawater oxygen-levels and the demise of much of the seabed bradoriid micro-benthos favoured a third group of arthropod micro-benthos, the ostracods. These animals adopted lifestyles that made them tolerant of changes in seawater O(2). Ostracods became the numerically dominant arthropod micro-benthos of the Phanerozoic. Our work has implications from an evolutionary context for understanding how oxygen-level in marine ecosystems drives behaviour.

Oxygen as a Driver of Early Arthropod Micro-Benthos Evolution

PubMed Central

Williams, Mark; Vannier, Jean; Corbari, Laure; Massabuau, Jean-Charles

2011-01-01

Background We examine the physiological and lifestyle adaptations which facilitated the emergence of ostracods as the numerically dominant Phanerozoic bivalve arthropod micro-benthos. Methodology/Principal Findings The PO2 of modern normoxic seawater is 21 kPa (air-equilibrated water), a level that would cause cellular damage if found in the tissues of ostracods and much other marine fauna. The PO2 of most aquatic breathers at the cellular level is much lower, between 1 and 3 kPa. Ostracods avoid oxygen toxicity by migrating to waters which are hypoxic, or by developing metabolisms which generate high consumption of O2. Interrogation of the Cambrian record of bivalve arthropod micro-benthos suggests a strong control on ecosystem evolution exerted by changing seawater O2 levels. The PO2 of air-equilibrated Cambrian-seawater is predicted to have varied between 10 and 30 kPa. Three groups of marine shelf-dwelling bivalve arthropods adopted different responses to Cambrian seawater O2. Bradoriida evolved cardiovascular systems that favoured colonization of oxygenated marine waters. Their biodiversity declined during intervals associated with black shale deposition and marine shelf anoxia and their diversity may also have been curtailed by elevated late Cambrian (Furongian) oxygen-levels that increased the PO2 gradient between seawater and bradoriid tissues. Phosphatocopida responded to Cambrian anoxia differently, reaching their peak during widespread seabed dysoxia of the SPICE event. They lacked a cardiovascular system and appear to have been adapted to seawater hypoxia. As latest Cambrian marine shelf waters became well oxygenated, phosphatocopids went extinct. Changing seawater oxygen-levels and the demise of much of the seabed bradoriid micro-benthos favoured a third group of arthropod micro-benthos, the ostracods. These animals adopted lifestyles that made them tolerant of changes in seawater O2. Ostracods became the numerically dominant arthropod micro-benthos of the Phanerozoic. Conclusions/Significance Our work has implications from an evolutionary context for understanding how oxygen-level in marine ecosystems drives behaviour. PMID:22164241

Cardiovascular consequences of bed rest: effect on maximal oxygen uptake

NASA Technical Reports Server (NTRS)

Convertino, V. A.

1997-01-01

Maximal oxygen uptake (VO2max) is reduced in healthy individuals confined to bed rest, suggesting it is independent of any disease state. The magnitude of reduction in VO2max is dependent on duration of bed rest and the initial level of aerobic fitness (VO2max), but it appears to be independent of age or gender. Bed rest induces an elevated maximal heart rate which, in turn, is associated with decreased cardiac vagal tone, increased sympathetic catecholamine secretion, and greater cardiac beta-receptor sensitivity. Despite the elevation in heart rate, VO2max is reduced primarily from decreased maximal stroke volume and cardiac output. An elevated ejection fraction during exercise following bed rest suggests that the lower stroke volume is not caused by ventricular dysfunction but is primarily the result of decreased venous return associated with lower circulating blood volume, reduced central venous pressure, and higher venous compliance in the lower extremities. VO2max, stroke volume, and cardiac output are further compromised by exercise in the upright posture. The contribution of hypovolemia to reduced cardiac output during exercise following bed rest is supported by the close relationship between the relative magnitude (% delta) and time course of change in blood volume and VO2max during bed rest, and also by the fact that retention of plasma volume is associated with maintenance of VO2max after bed rest. Arteriovenous oxygen difference during maximal exercise is not altered by bed rest, suggesting that peripheral mechanisms may not contribute significantly to the decreased VO2max. However reduction in baseline and maximal muscle blood flow, red blood cell volume, and capillarization in working muscles represent peripheral mechanisms that may contribute to limited oxygen delivery and, subsequently, lowered VO2max. Thus, alterations in cardiac and vascular functions induced by prolonged confinement to bed rest contribute to diminution of maximal oxygen uptake and reserve capacity to perform physical work.

Hypoxia tolerance in coral-reef triggerfishes (Balistidae)

NASA Astrophysics Data System (ADS)

Wong, Corrie C.; Drazen, Jeffrey C.; Callan, Chatham K.; Korsmeyer, Keith E.

2018-03-01

Despite high rates of photosynthetic oxygen production during the day, the warm waters of coral reefs are susceptible to hypoxia at night due to elevated respiration rates at higher temperatures that also reduce the solubility of oxygen. Hypoxia may be a challenge for coral-reef fish that hide in the reef to avoid predators at night. Triggerfishes (Balistidae) are found in a variety of reef habitats, but they also are known to find refuge in reef crevices and holes at night, which may expose them to hypoxic conditions. The critical oxygen tension ( P crit) was determined as the point below which oxygen uptake could not be maintained to support standard metabolic rate (SMR) for five species of triggerfish. The triggerfishes exhibited similar levels of hypoxia tolerance as other coral-reef and coastal marine fishes that encounter low oxygen levels in their environment. Two species, Rhinecanthus rectangulus and R. aculeatus, had the lowest P crit ( 3.0 kPa O2), comparable to the most hypoxia-tolerant obligate coral-dwelling gobies, while Odonus niger and Sufflamen bursa were moderately tolerant to hypoxia ( P crit 4.5 kPa), and Xanthichthys auromarginatus was intermediate ( P crit 3.7 kPa). These differences in P crit were not due to differences in oxygen demand, as all the species had a similar SMR once mass differences were taken into account. The results suggest that triggerfish species are adapted for different levels of hypoxia exposure during nocturnal sheltering within the reef.

Naturally high plasma glucose levels in mourning doves (Zenaida macroura) do not lead to high levels of reactive oxygen species in the vasculature.

PubMed

Smith, Christina L; Toomey, Matthew; Walker, Benjimen R; Braun, Eldon J; Wolf, Blair O; McGraw, Kevin; Sweazea, Karen L

2011-06-01

Plasma glucose (P(Glu)) concentrations in birds are 1.5-2 times higher than those of mammals of similar body mass. In mammals, sustained elevations of P(Glu) lead to oxidative stress and free radical-mediated scavenging of endogenous vasodilators (e.g., nitric oxide), contributing to elevated blood pressure. Despite the relatively high P(Glu) levels in birds, they appear resistant to the development of oxidative stress in tissues such as the heart, brain and kidneys. To our knowledge no information exists on oxidative stress susceptibility in the resistance vasculature of birds. Therefore, we compared endogenous antioxidant mechanisms in the resistance vasculature of mourning doves (MODO; Zenaida macroura) and rats (Rattus norvegicus). Reactive oxygen species (ROS) were assessed with the fluorescent indicator 7'-dichlorodihydrofluorescein diacetate, acetyl ester in mesenteric arteries from rats and wild-caught MODO. Despite having significantly higher P(Glu) than rats, there were no significant differences in ROS levels between mesenteric arteries from rats or doves. Although superoxide dismutase and catalase activities were lower in the plasma, total antioxidant capacity, uric acid, vitamin E (α-tocopherol), and carotenoids (lutein and zeaxanthin) were significantly higher in MODO than in rats. Thus, compared to rats, MODO have multiple circulating antioxidants that may prevent the development of oxidative stress in the vasculature. Copyright © 2011 Elsevier GmbH. All rights reserved.

Environmental Flow for Sungai Johor Estuary

NASA Astrophysics Data System (ADS)

Adilah, A. Kadir; Zulkifli, Yusop; Zainura, Z. Noor; Bakhiah, Baharim N.

2018-03-01

Sungai Johor estuary is a vital water body in the south of Johor and greatly affects the water quality in the Johor Straits. In the development of the hydrodynamic and water quality models for Sungai Johor estuary, the Environmental Fluid Dynamics Code (EFDC) model was selected. In this application, the EFDC hydrodynamic model was configured to simulate time varying surface elevation, velocity, salinity, and water temperature. The EFDC water quality model was configured to simulate dissolved oxygen (DO), dissolved organic carbon (DOC), chemical oxygen demand (COD), ammoniacal nitrogen (NH3-N), nitrate nitrogen (NO3-N), phosphate (PO4), and Chlorophyll a. The hydrodynamic and water quality model calibration was performed utilizing a set of site specific data acquired in January 2008. The simulated water temperature, salinity and DO showed good and fairly good agreement with observations. The calculated correlation coefficients between computed and observed temperature and salinity were lower compared with the water level. Sensitivity analysis was performed on hydrodynamic and water quality models input parameters to quantify their impact on modeling results such as water surface elevation, salinity and dissolved oxygen concentration. It is anticipated and recommended that the development of this model be continued to synthesize additional field data into the modeling process.

Effects of nitrite exposure on functional haemoglobin levels, bimodal respiration, and swimming performance in the facultative air-breathing fish Pangasianodon hypophthalmus.

PubMed

Lefevre, Sjannie; Jensen, Frank B; Huong, Do T T; Wang, Tobias; Phuong, Nguyen T; Bayley, Mark

2011-07-01

In this study we investigated nitrite (NO₂⁻) effects in striped catfish, a facultative air-breather. Fish were exposed to 0, 0.4, and 0.9 mM nitrite for 0, 1, 2, 4, and 7 days, and levels of functional haemoglobin, methaemoglobin (metHb) and nitrosyl haemoglobin (HbNO) were assessed using spectral deconvolution. Plasma concentrations of nitrite, nitrate, chloride, potassium, and sodium were also measured. Partitioning of oxygen consumption was determined to reveal whether elevated metHb (causing functional hypoxia) induced air-breathing. The effects of nitrite on maximum oxygen uptake (MO(2max)) and critical swimming speed (U(crit)) were also assessed. Striped catfish was highly tolerant to nitrite exposure, as reflected by a 96 h LC₅₀ of 1.65 mM and a moderate nitrite uptake into the blood. Plasma levels of nitrite reached a maximum after 1 day of exposure, and then decreased, never exceeding ambient levels. MetHb, HbNO and nitrate (a nitrite detoxification product) also peaked after 1 day and then decreased. Only high levels of nitrite and metHb caused reductions in MO(2max) and U(crit). The response of striped catfish contrasts with that seen in most other fish species and discloses efficient mechanisms of combating nitrite threats. Furthermore, even though striped catfish is an efficient air-breather, this species has the ability to sustain aerobic scope and swimming performance without air-breathing, even when faced with nitrite-induced reductions in blood oxygen carrying capacity. Our study is the first to confirm that high levels of nitrite and metHb reduce MO(2max) and thereby aerobic scope, while more moderate elevations fail to do so. Further studies are needed to elucidate the mechanisms underlying the low nitrite accumulation in striped catfish. Copyright © 2011 Elsevier B.V. All rights reserved.

Oxygen plasma immersion ion implantation treatment to enhance data retention of tungsten nanocrystal nonvolatile memory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Jer-Chyi, E-mail: jcwang@mail.cgu.edu.tw; Chang, Wei-Cheng; Lai, Chao-Sung, E-mail: cslai@mail.cgu.edu.tw

Data retention characteristics of tungsten nanocrystal (W-NC) memory devices using an oxygen plasma immersion ion implantation (PIII) treatment are investigated. With an increase of oxygen PIII bias voltage and treatment time, the capacitance–voltage hysteresis memory window is increased but the data retention characteristics become degraded. High-resolution transmission electron microscopy images show that this poor data retention is a result of plasma damage on the tunneling oxide layer, which can be prevented by lowering the bias voltage to 7 kV. In addition, by using the elevated temperature retention measurement technique, the effective charge trapping level of the WO{sub 3} film surrounding themore » W-NCs can be extracted. This measurement reveals that a higher oxygen PIII bias voltage and treatment time induces more shallow traps within the WO{sub 3} film, degrading the retention behavior of the W-NC memory.« less

Weight loss by Ppc-1, a novel small molecule mitochondrial uncoupler derived from slime mold.

PubMed

Suzuki, Toshiyuki; Kikuchi, Haruhisa; Ogura, Masato; Homma, Miwako K; Oshima, Yoshiteru; Homma, Yoshimi

2015-01-01

Mitochondria play a key role in diverse processes including ATP synthesis and apoptosis. Mitochondrial function can be studied using inhibitors of respiration, and new agents are valuable for discovering novel mechanisms involved in mitochondrial regulation. Here, we screened small molecules derived from slime molds and other microorganisms for their effects on mitochondrial oxygen consumption. We identified Ppc-1 as a novel molecule which stimulates oxygen consumption without adverse effects on ATP production. The kinetic behavior of Ppc-1 suggests its function as a mitochondrial uncoupler. Serial administration of Ppc-1 into mice suppressed weight gain with no abnormal effects on liver or kidney tissues, and no evidence of tumor formation. Serum fatty acid levels were significantly elevated in mice treated with Ppc-1, while body fat content remained low. After a single administration, Ppc-1 distributes into various tissues of individual animals at low levels. Ppc-1 stimulates adipocytes in culture to release fatty acids, which might explain the elevated serum fatty acids in Ppc-1-treated mice. The results suggest that Ppc-1 is a unique mitochondrial regulator which will be a valuable tool for mitochondrial research as well as the development of new drugs to treat obesity.

Liquid films on shake flask walls explain increasing maximum oxygen transfer capacities with elevating viscosity.

PubMed

Giese, Heiner; Azizan, Amizon; Kümmel, Anne; Liao, Anping; Peter, Cyril P; Fonseca, João A; Hermann, Robert; Duarte, Tiago M; Büchs, Jochen

2014-02-01

In biotechnological screening and production, oxygen supply is a crucial parameter. Even though oxygen transfer is well documented for viscous cultivations in stirred tanks, little is known about the gas/liquid oxygen transfer in shake flask cultures that become increasingly viscous during cultivation. Especially the oxygen transfer into the liquid film, adhering on the shake flask wall, has not yet been described for such cultivations. In this study, the oxygen transfer of chemical and microbial model experiments was measured and the suitability of the widely applied film theory of Higbie was studied. With numerical simulations of Fick's law of diffusion, it was demonstrated that Higbie's film theory does not apply for cultivations which occur at viscosities up to 10 mPa s. For the first time, it was experimentally shown that the maximum oxygen transfer capacity OTRmax increases in shake flasks when viscosity is increased from 1 to 10 mPa s, leading to an improved oxygen supply for microorganisms. Additionally, the OTRmax does not significantly undermatch the OTRmax at waterlike viscosities, even at elevated viscosities of up to 80 mPa s. In this range, a shake flask is a somehow self-regulating system with respect to oxygen supply. This is in contrary to stirred tanks, where the oxygen supply is steadily reduced to only 5% at 80 mPa s. Since, the liquid film formation at shake flask walls inherently promotes the oxygen supply at moderate and at elevated viscosities, these results have significant implications for scale-up. © 2013 Wiley Periodicals, Inc.

Hydrogen peroxide production regulates the mitochondrial function in insulin resistant muscle cells: effect of catalase overexpression.

PubMed

Barbosa, Marina R; Sampaio, Igor H; Teodoro, Bruno G; Sousa, Thais A; Zoppi, Claudio C; Queiroz, André L; Passos, Madla A; Alberici, Luciane C; Teixeira, Felipe R; Manfiolli, Adriana O; Batista, Thiago M; Cappelli, Ana Paula Gameiro; Reis, Rosana I; Frasson, Danúbia; Kettelhut, Isis C; Parreiras-e-Silva, Lucas T; Costa-Neto, Claudio M; Carneiro, Everardo M; Curi, Rui; Silveira, Leonardo R

2013-10-01

The mitochondrial redox state plays a central role in the link between mitochondrial overloading and insulin resistance. However, the mechanism by which the ROS induce insulin resistance in skeletal muscle cells is not completely understood. We examined the association between mitochondrial function and H2O2 production in insulin resistant cells. Our hypothesis is that the low mitochondrial oxygen consumption leads to elevated ROS production by a mechanism associated with reduced PGC1α transcription and low content of phosphorylated CREB. The cells were transfected with either the encoded sequence for catalase overexpression or the specific siRNA for catalase inhibition. After transfection, myotubes were incubated with palmitic acid (500μM) and the insulin response, as well as mitochondrial function and fatty acid metabolism, was determined. The low mitochondrial oxygen consumption led to elevated ROS production by a mechanism associated with β-oxidation of fatty acids. Rotenone was observed to reduce the ratio of ROS production. The elevated H2O2 production markedly decreased the PGC1α transcription, an effect that was accompanied by a reduced phosphorylation of Akt and CREB. The catalase transfection prevented the reduction in the phosphorylated level of Akt and upregulated the levels of phosphorylated CREB. The mitochondrial function was elevated and H2O2 production reduced, thus increasing the insulin sensitivity. The catalase overexpression improved mitochondrial respiration protecting the cells from fatty acid-induced, insulin resistance. This effect indicates that control of hydrogen peroxide production regulates the mitochondrial respiration preventing the insulin resistance in skeletal muscle cells by a mechanism associated with CREB phosphorylation and β-oxidation of fatty acids. Copyright © 2013 Elsevier B.V. All rights reserved.

Elevated Mitochondrial Reactive Oxygen Species and Cellular Redox Imbalance in Human NADPH-Oxidase-Deficient Phagocytes

PubMed Central

Sundqvist, Martina; Christenson, Karin; Björnsdottir, Halla; Osla, Veronica; Karlsson, Anna; Dahlgren, Claes; Speert, David P.; Fasth, Anders; Brown, Kelly L.; Bylund, Johan

2017-01-01

Chronic granulomatous disease (CGD) is caused by mutations in genes that encode the NADPH-oxidase and result in a failure of phagocytic cells to produce reactive oxygen species (ROS) via this enzyme system. Patients with CGD are highly susceptible to infections and often suffer from inflammatory disorders; the latter occurs in the absence of infection and correlates with the spontaneous production of inflammatory cytokines. This clinical feature suggests that NADPH-oxidase-derived ROS are not required for, or may even suppress, inflammatory processes. Experimental evidence, however, implies that ROS are in fact required for inflammatory cytokine production. By using a myeloid cell line devoid of a functional NADPH-oxidase and primary CGD cells, we analyzed intracellular oxidants, signs of oxidative stress, and inflammatory cytokine production. Herein, we demonstrate that phagocytes lacking a functional NADPH-oxidase, namely primary CGD phagocytes and a gp91phox-deficient cell line, display elevated levels of ROS derived from mitochondria. Accordingly, these cells, despite lacking the major source of cellular ROS, display clear signs of oxidative stress, including an induced expression of antioxidants and altered oxidation of cell surface thiols. These observed changes in redox state were not due to abnormalities in mitochondrial mass or membrane integrity. Finally, we demonstrate that increased mitochondrial ROS enhanced phosphorylation of ERK1/2, and induced production of IL8, findings that correlate with previous observations of increased MAPK activation and inflammatory cytokine production in CGD cells. Our data show that elevated baseline levels of mitochondria-derived oxidants lead to the counter-intuitive observation that CGD phagocytes are under oxidative stress and have enhanced MAPK signaling, which may contribute to the elevated basal production of inflammatory cytokines and the sterile inflammatory manifestations in CGD. PMID:29375548

Puget Sound Dissolved Oxygen Modeling Study: Development of an Intermediate-Scale Hydrodynamic Model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Zhaoqing; Khangaonkar, Tarang; Labiosa, Rochelle G.

2010-11-30

The Washington State Department of Ecology contracted with Pacific Northwest National Laboratory to develop an intermediate-scale hydrodynamic and water quality model to study dissolved oxygen and nutrient dynamics in Puget Sound and to help define potential Puget Sound-wide nutrient management strategies and decisions. Specifically, the project is expected to help determine 1) if current and potential future nitrogen loadings from point and non-point sources are significantly impairing water quality at a large scale and 2) what level of nutrient reductions are necessary to reduce or dominate human impacts to dissolved oxygen levels in the sensitive areas. In this study, anmore » intermediate-scale hydrodynamic model of Puget Sound was developed to simulate the hydrodynamics of Puget Sound and the Northwest Straits for the year 2006. The model was constructed using the unstructured Finite Volume Coastal Ocean Model. The overall model grid resolution within Puget Sound in its present configuration is about 880 m. The model was driven by tides, river inflows, and meteorological forcing (wind and net heat flux) and simulated tidal circulations, temperature, and salinity distributions in Puget Sound. The model was validated against observed data of water surface elevation, velocity, temperature, and salinity at various stations within the study domain. Model validation indicated that the model simulates tidal elevations and currents in Puget Sound well and reproduces the general patterns of the temperature and salinity distributions.« less

The effect of diet, temperature and intermittent low oxygen on the metabolism of rainbow trout.

PubMed

Stiller, Kevin T; Vanselow, Klaus H; Moran, Damian; Riesen, Guido; Koppe, Wolfgang; Dietz, Carsten; Schulz, Carsten

2017-03-01

An automated respirometer system was used to measure VO2, protein catabolism as ammonia quotient and the energy budget to evaluate whether the crude protein content of a standard protein (SP) diet (42·5 %) or a high-protein (HP) diet (49·5 %) influences metabolism in rainbow trout under challenging intermittent, low dissolved oxygen concentrations. In total, three temperature phases (12, 16, 20°C) were tested sequentially, each of which were split into two oxygen periods with 5 d of unmanipulated oxygen levels (50-70 %), followed by a 5d manipulated oxygen period (16.00-08.00 hours) with low oxygen (40-50 %) levels. For both diets, catabolic protein usage was lowest at 16°C and was not altered under challenging oxygen conditions. Low night-time oxygen elevated mean daily VO2 by 3-14 % compared with the unmanipulated oxygen period for both diets at all temperatures. The relative change in VO2 and retained energy during the intermittent low oxygen period was smaller for the HP diet compared with the SP diet. However, in absolute terms, the SP diet was superior to the HP diet as the former demonstrated 30-40 % lower protein fuel use rates, higher retained energy (1-4 % digestible energy) and slightly lowered VO2 (0-8 %) over the range of conditions tested. The decrease in retained energy under low oxygen conditions suggests that there is scope to improve the performance of SP diets under challenging conditions; however, this study suggests that simply increasing the dietary protein content is not a remedy, and other strategies need to be explored.

Sodium fluoride affects zebrafish behaviour and alters mRNA expressions of biomarker genes in the brain: Role of Nrf2/Keap1.

PubMed

Mukhopadhyay, Debdip; Priya, Pooja; Chattopadhyay, Ansuman

2015-09-01

Sodium fluoride (NaF), used as pesticides and for industrial purposes are deposited in the water bodies and therefore affects its biota. Zebrafish exposed to NaF in laboratory condition showed hyperactivity and frequent surfacing activity, somersaulting and vertical swimming pattern as compared to the control group. Reactive oxygen species level was elevated and glutathione level was depleted along with increased malondialdehyde content in the brain. Levels of glutathione-s-transferase (GST), catalase (CAT) and superoxide dismutase were also elevated in the treatment groups. Expression of mRNA of nuclear factor erythroid 2 related factor 2 (Nrf2) and its inhibitor Kelch-like ECH-associated protein 1 (Keap1) during stress condition were observed along with Gst, Cat, NADPH: quinone oxidoreductase 1(Nqo1) and p38. Except Keap1, all other genes exhibited elevated expression. Nrf2/Keap1 proteins had similar expression pattern as their corresponding mRNA. The findings in this study might help to understand the molecular mechanism of fluoride induced neurotoxicity in fish. Copyright © 2015 Elsevier B.V. All rights reserved.

Nasal high-flow therapy reduces work of breathing compared with oxygen during sleep in COPD and smoking controls: a prospective observational study

PubMed Central

Kirkness, Jason P.; Grote, Ludger; Fricke, Kathrin; Schwartz, Alan R.; Smith, Philip; Schneider, Hartmut

2017-01-01

Patients with chronic obstructive pulmonary disease (COPD) endure excessive resistive and elastic loads leading to chronic respiratory failure. Oxygen supplementation corrects hypoxemia but is not expected to reduce mechanical loads. Nasal high-flow (NHF) therapy supports breathing by reducing dead space, but it is unclear how it affects mechanical loads of patients with COPD. The objective of this study was to compare the effects of low-flow oxygen and NHF therapy on ventilation and work of breathing (WOB) in patients with COPD and controls during sleep. Patients with COPD (n = 12) and controls (n = 6) were recruited and submitted to polysomnography to measure sleep parameters and ventilation in response to administration of oxygen and NHF. A subset of six patients also had an esophageal catheter inserted for the purpose of measuring WOB. Patients with COPD had similar minute ventilation (V̇e) but lower tidal volumes than matched controls. With oxygen, SaO2was increased and V̇e was reduced in both controls and patients with COPD, but there was an increase in transcutaneous CO2 levels. NHF produced a greater reduction in V̇e and was associated with a reduction in CO2 levels. Although NHF halved WOB, oxygen produced only a minor reduction in this parameter. We conclude that oxygen produced little change in WOB, which was associated with CO2 elevations. On the other hand, NHF produced a large reduction in V̇e and WOB with a concomitant decrease in CO2 levels. Our data indicate that NHF improves alveolar ventilation during sleep compared with oxygen and room air in patients with COPD and therefore can decrease their cost of breathing. NEW & NOTEWORTHY Nasal high-flow (NHF) therapy can support ventilation in patients with chronic obstructive pulmonary disease during sleep by decreasing the work of breathing and improving CO2 levels. On the other hand, oxygen supplementation corrects hypoxemia, but it produces only a minimal reduction in work of breathing and is associated with increased CO2 levels. Therefore, NHF can be a useful method to assist ventilation in patients with increased respiratory mechanical loads. PMID:27815367

Effects of Ocean Acidification and Flow on Oxygen and pH Conditions of Developing Squid (Doryteuthis pealeii) Egg Cases

NASA Astrophysics Data System (ADS)

Panyi, A.; Long, M. H.; Mooney, T. A.

2016-02-01

While young animals found future cohorts and populations, these early life stages are often particularly susceptible to conditions of the local environment in which they develop. The oxygen and pH of this critical developmental environment is likely impacted by the nearby physical conditions and the animals own respirations. Yet, in nearly all cases, this microenvironment is unknown, limiting our understanding of animal tolerances to current and future OA and hypoxic conditions. This study investigated the oxygen and pH environment adjacent to and within the egg cases of a keystone species, the longfin squid, Doryteuthis pealeii, under ambient and elevated CO2 (400 and 2200 ppm), and across differing water flow rates (0, 1, and 10 cm/s) using microprobes. Under both CO2 treatments, oxygen and pH in the egg case centers dropped dramatically across development to levels generally considered metabolically stressful even for adults. In the ambient CO2 trial, oxygen concentrations reached a minimum of 4.351 µmol/L, and pH reached a minimum of 7.36. In the elevated CO2 trial, oxygen concentrations reached a minimum of 9.910 µmol/L, and pH reached a minimum of 6.79. Flow appeared to alleviate these conditions, with highest O2 concentrations in the egg cases exposed to 10 cm/s flow in both CO2 trials, across all age classes measured. Surprisingly, all tested egg cases successfully hatched, demonstrating that developing D. pealeii embryos have a strong tolerance for low oxygen and pH, but there were more unsuccessful embryos counted in the 0 and 1 cm/s flow conditions. Further climate change could place young, keystone squid outside of their physiological limits, but water flow may play a key role in mitigating developmental stress to egg case bound embryos by increasing available oxygen.

Programmatic Life Cycle Environmental Assessment for Smoke/Obscurants. Volume 2. Red, White, and Plasticized White Phosphorus

DTIC Science & Technology

1983-07-01

data on toxic effects of unreacted P4 on soil systems are available. (3) Aquatic systems . Aquatic toxicity data on WP are presented in section IV.f...elevated phosphorus levels in aquatic systems will cause adverse effects . Phosphoric acids may lower water pH in systems with low water hardness. A pH...eutrophication of the system , will cause detrimental effects on the fish population. Fish kills can occur over the winter due to low oxygen levels. The

Overshoot of atmospheric oxygen caused by the Paleoproterozoic snowball glaciation: constraining its magnitude and duration from biogeochemical cycle modeling

NASA Astrophysics Data System (ADS)

Harada, M.; Ozaki, K.; Tajika, E.; Sekine, Y.

2014-12-01

Rise of atmospheric oxygen in the Paleoproterozoic has been long recognized as a unidirectional, stepwise oxidation event. However, recent geochemical studies have reported the occurrences of deep-water oxygenation and sulfate accumulation in the Paleoproterozoic oceans [e.g., 1], suggesting that the oxidation was a dynamic transition associated with an overshoot of oxygen (so called, 'the Great Oxygen Transition' or GOT) [2]. During the GOT, the oxygen levels might have achieved 0.1-1 Present Atmospheric Level (PAL) over ~108 years [2]. Such an intense long-term oxygen overshoot appears to require some specific mechanism and strong oxidative forcing as a trigger. In this study, we provide the first numerical model that is capable of explaining the dynamics of the atmospheric oxygen during the GOT. We focus on a climate jump at the end of the Paleoproterozoic snowball glaciation as a trigger, and constrain the magnitude and duration of the snowball-induced oxygenation by using a biogeochemical cycle model. The results show that super greenhouse condition after the glaciation causes an increase in nutrient input from the continent to the oceans, which lead to a high rate of organic carbon burial in the oceans. This triggers a rapid jump in oxygen levels from low (<10-5 PAL) to high (~0.01 PAL) steady states within <104 years after deglaciation. The jump in oxygen levels is followed by the massive deposition of carbonate minerals, which corresponds to the "cap-carbonates". The elevated rate of organic carbon burial is prolonged over ~106 years, which results in an overshoot of atmospheric oxygen by up to ~0.1-1 PAL. The overshoot lasts for ~107-108 years because net consumption of oxygen accumulated in the atmosphere does not proceed efficiently. Such an extensive overshoot causes the oxygenation of the deep-water, and lead to the accumulation of sulfate ions by up to 1-10 mM and the deposition of sulfate minerals in the oceans. These results are in good agreement with the geological and geochemical data in the Paleoproterozoic [2, 3], implying that the Paleoproterozoic snowball glaciation would have been a sufficiently strong forcing to trigger the GOT. [1] Canfield et al. 2013, Pros. Natl. Acad. Sci. U.S.A., 110, 16736. [2] Lyons et al. 2014, Nature, 506, 307. [3] Schröder et al. 2008, Terra Nova, 20, 108.

Effects of positive end-expiratory pressure on intracranial pressure in mechanically ventilated dogs under hyperbaric oxygenation.

PubMed

Sun, Qing; Wu, Di; Yu, Tao; Yang, Ying; Wei, Li; Lv, Fuxiang; Gao, Guangkai

2014-01-01

Mechanical ventilation with positive end-expiratory pressure (PEEP) has been advocated as an essential life support for critical patients. However, its side effect, which is demonstrated by an elevation of intracranial pressure (ICP) under normobaric (NBO2) conditions, is potentially detrimental to patients. Hyperbaric oxygen (HBO2) therapy, on the other hand, is frequently applied for the same group of patients, and its efficacy is shown by maintaining a higher PaO2 and a reduced ICP. Our study investigated the effect of HBO2 and NBO2 on ICP with or without PEEP ventilation on healthy dogs by comparing cerebrospinal fluid pressure (CSFP) and concluded that the elevation of PEEP resulted in a significant increase of ICP (CSFP) under both conditions (p < 0.05). HBO2 leads to a lower ICP increase compared to the NBO2 group. Under the same level of PEEP, the joint use of PEEP and HBO2 is safe and highly practical in clinical medicine.

Water resources data, Kansas, water year 2004

USGS Publications Warehouse

Putnam, J.E.; Schneider, D.R.

2005-01-01

Water-resources data for the 2004 water year for Kansas consist of records of stage, discharge, and water quality of streams; elevation and contents of lakes and reservoirs; and water levels of ground-water wells. This report contains records for water discharge at 155 complete-record gaging stations; elevation and contents at 17 lakes and reservoirs; water-quality records at 2 precipitation stations, water-level data at 14 observation wells; and records of specific conductance, pH, water temperature, dissolved oxygen, and turbidity at 16 gaging stations and 2 lakes with water-quality monitors. Also included are discharge data for 29 high-flow partial-record stations. These data represent that part of the National Water Information System collected by the U.S. Geological Survey in cooperation with local, State, and Federal agencies in Kansas.

Oxygenation-Enhanced Radiation Therapy of Breast Tumors

DTIC Science & Technology

2011-11-01

development of stabilized perfluorocarbon emulsions as oxygen carriers, their characterization, and response to external triggers, including...elevated temperature, reduced pressure, and dwell time. Targeted oxygenation, perfluorocarbon emulsions, breast cancer 29 The University of Utah Salt...investigation of the proposed novel strategy of radio sensitization of hypoxic breast tumors by targeted oxygen release from perfluorocarbon oxygen

Seed storage at elevated partial pressure of oxygen, a fast method for analysing seed ageing under dry conditions.

PubMed

Groot, S P C; Surki, A A; de Vos, R C H; Kodde, J

2012-11-01

Despite differences in physiology between dry and relative moist seeds, seed ageing tests most often use a temperature and seed moisture level that are higher than during dry storage used in commercial practice and gene banks. This study aimed to test whether seed ageing under dry conditions can be accelerated by storing under high-pressure oxygen. methods: Dry barley (Hordeum vulgare), cabbage (Brassica oleracea), lettuce (Lactuca sativa) and soybean (Glycine max) seeds were stored between 2 and 7 weeks in steel tanks under 18 MPa partial pressure of oxygen. Storage under high-pressure nitrogen gas or under ambient air pressure served as controls. The method was compared with storage at 45 °C after equilibration at 85 % relative humidity and long-term storage at the laboratory bench. Germination behaviour, seedling morphology and tocopherol levels were assessed. The ageing of the dry seeds was indeed accelerated by storing under high-pressure oxygen. The morphological ageing symptoms of the stored seeds resembled those observed after ageing under long-term dry storage conditions. Barley appeared more tolerant of this storage treatment compared with lettuce and soybean. Less-mature harvested cabbage seeds were more sensitive, as was the case for primed compared with non-primed lettuce seeds. Under high-pressure oxygen storage the tocopherol levels of dry seeds decreased, in a linear way with the decline in seed germination, but remained unchanged in seeds deteriorated during storage at 45 °C after equilibration at 85 % RH. Seed storage under high-pressure oxygen offers a novel and relatively fast method to study the physiology and biochemistry of seed ageing at different seed moisture levels and temperatures, including those that are representative of the dry storage conditions as used in gene banks and commercial practice.

Total dissolved gas, barometric pressure, and water temperature data, lower Columbia River, Oregon and Washington, 1996

USGS Publications Warehouse

Tanner, Dwight Q.; Harrison, Howard E.; McKenzie, Stuart W.

1996-01-01

Increased levels of total dissolved gas pressure can cause gas-bubble trauma in fish downstream from dams on the Columbia River. In cooperation with the U.S. Army Corps of Engineers, the U.S. Geological Survey collected data on total dissolved gas pressure, barometric pressure, water temperature, and dissolved oxygen pressure at 11 stations on the lower Columbia River from the John Day forebay (river mile 215.6) to Wauna Mill (river mile 41.9) from March to September 1996. Methods of data collection, review, and processing are described in this report. Summaries of daily minimum, maximum, and mean hourly values are presented for total dissolved gas pressure, barometric pressure, and water temperature. Hourly values for these parameters are presented graphically. Dissolved oxygen data are not presented in this report because the quality-control data show that the data have poor precision and high bias. Suggested changes to monitoring procedures for future studies include (1) improved calibration procedures for total dissolved gas and dissolved oxygen to better define accuracy at elevated levels of supersaturation and (2) equipping dissolved oxygen sensors with stirrers because river velocities at the shoreline monitoring stations probably cannot maintain an adequate flow of water across the membrane surface of the dissolved oxygen sensor.

SET8 is involved in the regulation of hyperglycemic memory in human umbilical endothelial cells.

PubMed

Chen, Xiangyuan; Wu, Qichao; Jiang, Hui; Wang, Jiaqiang; Zhao, Yanjun; Xu, Yajun; Zhu, Minmin

2018-05-14

Hyperglycemic memory occurs in diabetic cardiovascular complications, but the underlying mechanism remains to be elucidated. Although the depletion of SET8 leads to increased mitochondrial oxidative stress via increasing cellular reactive oxygen species (ROS) production, the role of SET8 in hyperglycemic memory-induced mitochondrial dysfunction is not well understood. Here, we investigated the role of SET8 in this setting. Our results showed that high glucose-induced vascular inflammation, ROS production and apoptosis remained at high levels even when glucose returned to normal level. Elevated glucose reduced SET8 expression, which also remained at low level after returning to normoglycemia. SET8 overexpression protected cells from elevated glucose and hyperglycemic memory-induced endothelial injury by blocking ROS accumulation, attenuating vascular inflammation, and restoring nitric oxide production. Thus, our results suggest that SET8 may be a key mediator in hyperglycemic memory.

Why do premature newborn infants display elevated blood adenosine levels?

PubMed

Panfoli, Isabella; Cassanello, Michela; Bruschettini, Matteo; Colella, Marina; Cerone, Roberto; Ravera, Silvia; Calzia, Daniela; Candiano, Giovanni; Ramenghi, Luca

2016-05-01

Our preliminary data show high levels of adenosine in the blood of very low birth weight (VLBW) infants, positively correlating to their prematurity (i.e. body weight class). This prompted us to look for a mechanism promoting such impressive adenosine increase. We hypothesized a correlation with oxygen challenge. In fact, it is recognized that either oxygen lack or its excess contribute to the pathogenesis of the injuries of prematurity, such as retinopathy (ROP) and periventricular white matter lesions (PWMI). The optimal concentration of oxygen for resuscitation of VLBW infants is currently under revision. We propose that the elevated adenosine blood concentrations of VLBW infants recognizes two sources. The first could be its activity-dependent release from unmyelinated brain axons. Adenosine in this respect would be an end-product of the hypometabolic VLBW newborn unmyelinated axon intensely firing in response to the environmental stimuli consequent to premature birth. Adenosine would be eventually found in the blood due to blood-brain barrier immaturity. In fact, adenosine is the primary activity-dependent signal promoting differentiation of premyelinating oligodendrocyte progenitor cells (OPC) into myelinating cells in the Central Nervous System, while inhibiting their proliferation and inhibiting synaptic function. The second, would be the ecto-cellular ATP synthesized by the endothelial cell plasmalemma exposed to ambient oxygen concentrations due to premature breathing, especially in lung. ATP would be rapidly transformed into adenosine by the ectonucleotidase activities such as NTPDase I (CD39), and NT5E (CD73). An ectopic extra-mitochondrial aerobic ATP synthetic ability was reported in many cell plasma-membranes, among which endothelial cells. The potential implications of the cited hypotheses for the neonatology area would be great. The amount of oxygen administration for reviving of newborns would find a molecular basis for its assessment. VLBW infants may be regarded as those in which premature exposure to ambient oxygen concentrations and oxidative stress causes a premature functioning of the extra-mitochondrial oxidative phosphorylation primarily in axons and endothelium. Adenosine may become a biomarker of prematurity risk, whose implications further studies may assess. Copyright © 2016 Elsevier Ltd. All rights reserved.

Mitochondrial and Cytoplasmic ROS Have Opposing Effects on Lifespan

PubMed Central

Schaar, Claire E.; Dues, Dylan J.; Spielbauer, Katie K.; Machiela, Emily; Cooper, Jason F.; Senchuk, Megan; Hekimi, Siegfried; Van Raamsdonk, Jeremy M.

2015-01-01

Reactive oxygen species (ROS) are highly reactive, oxygen-containing molecules that can cause molecular damage within the cell. While the accumulation of ROS-mediated damage is widely believed to be one of the main causes of aging, ROS also act in signaling pathways. Recent work has demonstrated that increasing levels of superoxide, one form of ROS, through treatment with paraquat, results in increased lifespan. Interestingly, treatment with paraquat robustly increases the already long lifespan of the clk-1 mitochondrial mutant, but not other long-lived mitochondrial mutants such as isp-1 or nuo-6. To genetically dissect the subcellular compartment in which elevated ROS act to increase lifespan, we deleted individual superoxide dismutase (sod) genes in clk-1 mutants, which are sensitized to ROS. We find that only deletion of the primary mitochondrial sod gene, sod-2 results in increased lifespan in clk-1 worms. In contrast, deletion of either of the two cytoplasmic sod genes, sod-1 or sod-5, significantly decreases the lifespan of clk-1 worms. Further, we show that increasing mitochondrial superoxide levels through deletion of sod-2 or treatment with paraquat can still increase lifespan in clk-1;sod-1 double mutants, which live shorter than clk-1 worms. The fact that mitochondrial superoxide can increase lifespan in worms with a detrimental level of cytoplasmic superoxide demonstrates that ROS have a compartment specific effect on lifespan – elevated ROS in the mitochondria acts to increase lifespan, while elevated ROS in the cytoplasm decreases lifespan. This work also suggests that both ROS-dependent and ROS-independent mechanisms contribute to the longevity of clk-1 worms. PMID:25671321

Detection of HOCl-mediated protein oxidation products in the extracellular matrix of human atherosclerotic plaques.

PubMed Central

Woods, Alan A; Linton, Stuart M; Davies, Michael J

2003-01-01

Oxidation is believed to play a role in atherosclerosis. Oxidized lipids, sterols and proteins have been detected in early, intermediate and advanced human lesions at elevated levels. The spectrum of oxidized side-chain products detected on proteins from homogenates of advanced human lesions has been interpreted in terms of the occurrence of two oxidative mechanisms, one involving oxygen-derived radicals catalysed by trace transition metal ions, and a second involving chlorinating species (HOCl or Cl2), generated by the haem enzyme myeloperoxidase (MPO). As MPO is released extracellularly by activated monocytes (and possibly macrophages) and is a highly basic protein, it would be expected to associate with polyanions such as the glycosaminoglycans of the extracellular matrix, and might result in damage being localized at such sites. In this study proteins extracted from extracellular matrix material obtained from advanced human atherosclerotic lesions are shown to contain elevated levels of oxidized amino acids [3,4-dihydroxyphenylalanine (DOPA), di-tyrosine, 2-hydroxyphenylalanine ( o-Tyr)] when compared with healthy (human and pig) arterial tissue. These matrix-derived materials account for 83-96% of the total oxidized protein side-chain products detected in these plaques. Oxidation of matrix components extracted from healthy artery tissue, and model proteins, with reagent HOCl is shown to give rise to a similar pattern of products to those detected in advanced human lesions. The detection of elevated levels of DOPA and o-Tyr, which have been previously attributed to the occurrence of oxygen-radical-mediated reactions, by HOCl treatment, suggests an alternative route to the formation of these materials in plaques. This is believed to involve the formation and subsequent decomposition of protein chloramines. PMID:12456264

An elevated respiratory quotient predicts complications after cardiac surgery under extracorporeal circulation: an observational pilot study.

PubMed

Piot, J; Hébrard, A; Durand, M; Payen, J F; Albaladejo, P

2018-04-17

Following cardiac surgery, hyperlactatemia due to anaerobic metabolism is associated with an increase in both morbidity and mortality. We previously found that an elevated respiratory quotient (RQ) predicts anaerobic metabolism. In the present study we aimed to demonstrate that it is also associated with poor outcome following cardiac surgery. This single institution, prospective, observational study includes all those patients that were consecutively admitted to the intensive care unit (ICU) after cardiac surgery with cardiopulmonary bypass, that had also been monitored using pulmonary artery catheter. Data were recorded at admission (H0) and after one hour (H1) including: oxygen consumption ([Formula: see text]), carbon dioxide production ([Formula: see text]), RQ ([Formula: see text]), lactate levels and mixed venous oxygen saturation ([Formula: see text]). The primary endpoint was defined as mortality at 30 days. Comparison of the area under the curve (AUC) for receiver operating characteristic curves was used to analyze the prognostic predictive value of RQ, lactate levels and [Formula: see text], in terms of patient outcome. We studied 151 patients admitted to the ICU between May 2015 and February 2016. Seventy eight patients experienced a worse than expected outcome in the post-operative period, and among those seven died. RQ at H1 in non-survivors ([Formula: see text]) was higher than in survivors ([Formula: see text]; p = 0.02). The AUC for RQ to predict mortality was 0.77 (IC 95% [0.70-0.84]), with a threshold value of 0.76 (sensitivity 64%, specificity 100%). By comparison, the AUC for lactate levels was significantly superior (AUClact 0.89, IC 95% [0.83-0.93], p = 0.02). In this study, elevated RQ appeared to be predictive of mortality after cardiac surgery with CPB.

Atmospheric oxygen level affects growth trajectory, cardiopulmonary allometry and metabolic rate in the American alligator (Alligator mississippiensis)

PubMed Central

Owerkowicz, Tomasz; Elsey, Ruth M.; Hicks, James W.

2009-01-01

Summary Recent palaeoatmospheric models suggest large-scale fluctuations in ambient oxygen level over the past 550 million years. To better understand how global hypoxia and hyperoxia might have affected the growth and physiology of contemporary vertebrates, we incubated eggs and raised hatchlings of the American alligator. Crocodilians are one of few vertebrate taxa that survived these global changes with distinctly conservative morphology. We maintained animals at 30°C under chronic hypoxia (12% O2), normoxia (21% O2) or hyperoxia (30% O2). At hatching, hypoxic animals were significantly smaller than their normoxic and hyperoxic siblings. Over the course of 3 months, post-hatching growth was fastest under hyperoxia and slowest under hypoxia. Hypoxia, but not hyperoxia, caused distinct scaling of major visceral organs–reduction of liver mass, enlargement of the heart and accelerated growth of lungs. When absorptive and post-absorptive metabolic rates were measured in juvenile alligators, the increase in oxygen consumption rate due to digestion/absorption of food was greatest in hyperoxic alligators and smallest in hypoxic ones. Hyperoxic alligators exhibited the lowest breathing rate and highest oxygen consumption per breath. We suggest that, despite compensatory cardiopulmonary remodelling, growth of hypoxic alligators is constrained by low atmospheric oxygen supply, which may limit their food utilisation capacity. Conversely, the combination of elevated metabolism and low cost of breathing in hyperoxic alligators allows for a greater proportion of metabolised energy to be available for growth. This suggests that growth and metabolic patterns of extinct vertebrates would have been significantly affected by changes in the atmospheric oxygen level. PMID:19376944

Exercise intolerance in Type 2 diabetes: is there a cardiovascular contribution?

PubMed

Poitras, Veronica J; Hudson, Robert W; Tschakovsky, Michael E

2018-05-01

Physical activity is critically important for Type 2 diabetes management, yet adherence levels are poor. This might be partly due to disproportionate exercise intolerance. Submaximal exercise tolerance is highly sensitive to muscle oxygenation; impairments in exercising muscle oxygen delivery may contribute to exercise intolerance in Type 2 diabetes since there is considerable evidence for the existence of both cardiac and peripheral vascular dysfunction. While uncompromised cardiac output during submaximal exercise is consistently observed in Type 2 diabetes, it remains to be determined whether an elevated cardiac sympathetic afferent reflex could sympathetically restrain exercising muscle blood flow. Furthermore, while deficits in endothelial function are common in Type 2 diabetes and are often cited as impairing exercising muscle oxygen delivery, no direct evidence in exercise exists, and there are several other vasoregulatory mechanisms whose dysfunction could contribute. Finally, while there are findings of impaired oxygen delivery, conflicting evidence also exists. A definitive conclusion that Type 2 diabetes compromises exercising muscle oxygen delivery remains premature. We review these potentially dysfunctional mechanisms in terms of how they could impair oxygen delivery in exercise, evaluate the current literature on whether an oxygen delivery deficit is actually manifest, and correspondingly identify key directions for future research.

Anaerobic metabolism at thermal extremes: a metabolomic test of the oxygen limitation hypothesis in an aquatic insect.

PubMed

Verberk, W C E P; Sommer, U; Davidson, R L; Viant, M R

2013-10-01

Thermal limits in ectotherms may arise through a mismatch between supply and demand of oxygen. At higher temperatures, the ability of their cardiac and ventilatory activities to supply oxygen becomes insufficient to meet their elevated oxygen demand. Consequently, higher levels of oxygen in the environment are predicted to enhance tolerance of heat, whereas reductions in oxygen are expected to reduce thermal limits. Here, we extend previous research on thermal limits and oxygen limitation in aquatic insect larvae and directly test the hypothesis of increased anaerobic metabolism and lower energy status at thermal extremes. We quantified metabolite profiles in stonefly nymphs under varying temperatures and oxygen levels. Under normoxia, the concept of oxygen limitation applies to the insects studied. Shifts in the metabolome of heat-stressed stonefly nymphs clearly indicate the onset of anaerobic metabolism (e.g., accumulation of lactate, acetate, and alanine), a perturbation of the tricarboxylic acid cycle (e.g., accumulation of succinate and malate), and a decrease in energy status (e.g., ATP), with corresponding decreases in their ability to survive heat stress. These shifts were more pronounced under hypoxic conditions, and negated by hyperoxia, which also improved heat tolerance. Perturbations of metabolic pathways in response to either heat stress or hypoxia were found to be somewhat similar but not identical. Under hypoxia, energy status was greatly compromised at thermal extremes, but energy shortage and anaerobic metabolism could not be conclusively identified as the sole cause underlying thermal limits under hyperoxia. Metabolomics proved useful for suggesting a range of possible mechanisms to explore in future investigations, such as the involvement of leaking membranes or free radicals. In doing so, metabolomics provided a more complete picture of changes in metabolism under hypoxia and heat stress.

Combined effects of hypoxia and ammonia to Daphnia similis estimated with life-history traits.

PubMed

Lyu, Kai; Cao, Huansheng; Chen, Rui; Wang, Qianqian; Yang, Zhou

2013-08-01

The degradation of cyanobacterial blooms often causes hypoxia and elevated concentrations of ammonia, which can aggravate the adverse effects of blooms on aquatic organisms. However, it is not clear how one stressor would work in the presence of other coexistent stressors. We studied the toxic effects of elevated ammonia under hypoxia using a common yet important cladoceran species Daphnia similis isolated from heavily eutrophicated Lake Taihu. A 3 × 2 factorial experimental design was conducted with animals exposed to three un-ionized ammonia levels under two dissolved oxygen levels. Experiments lasted for 14 days and we recorded the life-history traits such as survival, molt, maturation, and fecundity. Results showed that hypoxia significantly decreased survival time and the number of molts of D. similis, whereas ammonia had no effect on them. Elevated ammonia significantly delayed development to maturity in tested animals and decreased their body sizes at maturity. Both ammonia and hypoxia were significantly detrimental to the number of broods, the number of offspring per female, and the number of total offspring per female, and significantly synergistic interactions were detected. Our data clearly demonstrate that elevated ammonia and hypoxia derived from cyanobacterial blooms synergistically affect the cladoceran D. similis.

Marked elevation of hepatic transaminases in recipients of an orthotopic liver transplant from a brain-dead donor receiving extracorporeal membrane oxygenation.

PubMed

Teng-Wei, Chen; Chung-Bao, Hsieh; Chan, De-Chuan; Yu, Jyh-Cherng; Kuo, Shih-Ming; Tsai, Chien-Sung; Fan, Hsiu-Lung

2014-12-29

Hemodynamic instability can lead to failure of donor organ procurement in brain-dead donors. Extracorporeal membrane oxygenation (ECMO) has been used in non-heart-beating donors to increase the donor pool, but the use of ECMO to salvage donor organs has been rarely used. We aimed to analyze postoperative liver function test results in patients receiving orthotopic liver transplants from ECMO-supported brain-dead donors. We retrospectively reviewed the records of 43 recipients of orthotopic liver transplantation from May 2009 to June 2012. Six recipients received liver grafts from ECMO-maintained donors designated as the ECMO group (n=6). The remaining patients were assigned to the non-ECMO group (n=37). Complication and mortality rates and liver function test results on postoperative days 1, 3, 5, 7, and 14 were compared between the 2 groups. Serum glutamate oxaloacetate transaminase and serum glutamate pyruvate transaminase levels were significantly elevated on postoperative Day 1 in the ECMO group. There were no significant differences in the complication and overall survival rates between the 2 groups (P=0.411). Although serum transaminases markedly elevated on postoperative Day 1, ECMO successfully preserved potential liver grafts in hemodynamically unstable brain-dead donors.

Postprandial gastrointestinal blood flow, oxygen consumption and heart rate in rainbow trout (Oncorhynchus mykiss).

PubMed

Eliason, Erika J; Higgs, David A; Farrell, Anthony P

2008-04-01

The present study is the first to simultaneously and continuously measure oxygen consumption (MO(2)) and gastrointestinal blood flow (q(gi)) in fish. In addition, while it is the first to compare the effects of three isoenergetic diets on q(gi) in fish, no significant differences among diets were found for postprandial MO(2), q(gi) or heart rate (f(H)) in rainbow trout, Oncorhynchus mykiss. Postprandial q(gi), f(H) and MO(2) were significantly elevated above baseline levels by 4 h. Postprandial q(gi) peaked at 136% above baseline after 11 h, f(H) peaked at 110% above baseline after 14 h and MO(2) peaked at 96% above baseline after 27 h. Moreover, postprandial MO(2) remained significantly elevated above baseline longer than q(gi) (for 41 h and 30 h, respectively), perhaps because most of the increase in MO(2) associated with feeding is due to protein handling, a process that continues following the absorption of nutrients which is thought to be the primary reason for the elevation of q(gi). In addition to the positive relationships found between postprandial MO(2) and q(gi) and between postprandial MO(2) and f(H), we discovered a novel relationship between postprandial q(gi) and f(H).

Cardiovascular and metabolic activity at rest and during psychological and physical challenge in normotensives and subjects with mildly elevated blood pressure.

PubMed

Sims, J; Carroll, D

1990-03-01

Heart rate, systolic and diastolic blood pressure, and respiratory and metabolic activity were recorded prior to and during mental arithmetic and a video game task in 20 young men with mildly elevated casual systolic blood pressures. Twenty-five unambiguously normotensive young men were tested under the same protocol. For pretask baseline physiological activity, group differences emerged for all cardiovascular and metabolic variables; thus the elevated blood pressure group displayed not only higher resting cardiovascular levels than normotensive subjects, but higher levels of metabolic activity too. With regard to change in physiological activity from rest to task, the group with mildly elevated blood pressure showed reliably larger increases in heart rate to the mental arithmetic task than the normotensive subjects. These effects, however, were not paralleled by group differences in metabolic activity increase. Physiological measures were also taken prior to and during graded dynamic exercise. The subsequent calculation of individual heart rate-oxygen consumption exercise regression lines allowed the comparison of actual and predicted heart rates during psychological challenge. The subjects with mildly elevated blood pressure displayed significantly greater discrepancies between actual and predicted heart rate values than normotensives during the psychological tasks in general and mental arithmetic in particular. Group differences in physiological activity during exercise largely reflected the pattern seen at rest. A possible exception here was systolic blood pressure. Not only were systolic blood pressure levels higher throughout the exercise phase for mildly elevated blood pressure subjects, but this group evidenced more of an increase from rest to exercise than the normotensives.

Water Resources Data, Kansas, Water Year 2001

USGS Publications Warehouse

Putnam, J.E.; Lacock, D.L.; Schneider, D.R.

2002-01-01

Water-resources data for the 2001 water year for Kansas consist of records of stage, discharge, and water quality of streams; elevation and contents of lakes and reservoirs; and water levels of ground-water wells. This report contains records for water discharge at 145 complete-record gaging stations; elevation and contents at 20 lakes and reservoirs; waterquality records at 2 precipitation stations, water-level data at 19 observation wells; and records of specific conductance, pH, water temperature, dissolved oxygen, and turbidity at 11 gaging stations. Also included are discharge data for 26 high-flow partial-record stations, miscellaneous onsite water-quality data collected at 140 stations, and suspended-sediment concentration for 12 stations. These data represent that part of the National Water Information System collected by the U.S. Geological Survey in cooperation with local, State, and Federal agencies in Kansas.

Water Resources Data, Kansas, Water Year 2002

USGS Publications Warehouse

Putnam, J.E.; Schneider, D.R.

2003-01-01

Water-resources data for the 2002 water year for Kansas consist of records of stage, discharge, and water quality of streams; elevation and contents of lakes and reservoirs; and water levels of ground-water wells. This report contains records for water discharge at 149 complete-record gaging stations; elevation and contents at 20 lakes and reservoirs; waterquality records at 2 precipitation stations, water-level data at 18 observation wells; and records of specific conductance, pH, water temperature, dissolved oxygen, and turbidity at 11 gaging stations. Also included are discharge data for 26 high-flow partial-record stations, miscellaneous onsite water-quality data collected at 142 stations, and suspended-sediment concentration for 12 stations. These data represent that part of the National Water Information System collected by the U.S. Geological Survey in cooperation with local, State, and Federal agencies in Kansas.

Water Resources Data, Kansas, Water Year 2000

USGS Publications Warehouse

Putnam, J.E.; Lacock, D.L.; Schneider, D.R.; Carlson, M.D.

2001-01-01

Water-resources data for the 2000 water year for Kansas consist of records of stage, discharge, and water quality of streams; elevation and contents of lakes and reservoirs; and water levels of ground-water wells. This report contains records for water discharge at 144 complete-record gaging stations; elevation and contents at 19 lakes and reservoirs; water-quality records at 2 precipitation stations, water-level data at 18 observation wells; and records of specific conductance, pH, water temperature, dissolved oxygen, and turbidity at 8 gaging stations. Also included are discharge data for 26 high-flow partial-record stations, and miscellaneous onsite water-quality data collected at 134 stations, and suspended-sediment concentration for 12 stations. These data represent that part of the National Water Information System collected by the U.S. Geological Survey in cooperation with local, State, and Federal agencies in Kansas.

Water Resources Data, Kansas, Water Year 1999

USGS Publications Warehouse

Putnam, J.E.; Lacock, D.L.; Schneider, D.R.; Carlson, M.D.

2000-01-01

Water-resources data for the 1999 water year for Kansas consist of records of stage, discharge, and water quality of streams; elevation and contents of lakes and reservoirs; and water levels of ground-water wells. This report contains records for water discharge at 143 gaging stations; elevation and contents at 19 watershed lakes and reservoirs; and water-level data at 19 observation wells; and records of specific conductance, pH, water temperature, dissolved oxygen, and turbidity at 4 stations. Also included are data for 26 high-flow and 2 low-flow partial-record stations; and 2 chemical quality of precipitation stations. Miscellaneous onsite water-quality data were collected at 132 stations. These data represent that part of the National Water Information System collected by the U.S. Geological Survey in cooperation with State, local, and Federal agencies in Kansas.

The First 10 Years of Aerobic Exercise Responses to Long-Duration ISS Flights.

PubMed

Moore, Alan D; Lynn, Peggy A; Feiveson, Alan H

2015-12-01

Aerobic deconditioning may occur during International Space Station (ISS) flights. This paper documents findings from exercise testing conducted before, during, and after ISS expeditions. There were 30 male and 7 female astronauts on ISS missions (48 to 219 d, mean 163 d) who performed cycle exercise protocols consisting of 5-min stages eliciting 25%, 50%, and 75% peak oxygen uptake (Vo(2peak)). Tests were conducted 30 to 90 d before missions, on flight day 15 and every 30 flight days thereafter, and on recovery (R) days +5 and +30. During pre- and postflight tests, heart rate (HR) and metabolic gas exchange were measured. During flight, extrapolation of the HR and Vo2 relationship to preflight-measured peak HR provided an estimate of Vo(2peak), referred to as the aerobic capacity index (ACI). HR during each exercise stage was elevated (P < 0.05) and oxygen pulse was reduced (P < 0.05) on R+5 compared to preflight; however, no other metabolic gas analysis values significantly changed. Compared to preflight, the ACI declined (P < 0.001) on R+5, but recovered to levels greater than preflight by R+30 (P = 0.008). During flight, ACI decreased below preflight values, but increased with mission duration (P < 0.001). Aerobic deconditioning likely occurs initially during flight, but ACI recovers toward preflight levels as flight duration increases, presumably due to performance of exercise countermeasures. Elevated HR and lowered oxygen pulse on R+5 likely results from some combination of relative hypovolemia, lowered cardiac stroke volume, reduced cardiac distensibility, and anemia, but recovery occurs by R+30.

Comparison of the Protective Effects of Melatonin and Silymarin Against Gentamicin-Induced Nephrotoxicity in Rats.

PubMed

Ghaznavi, Habib; Mehrzadi, Saeed; Dormanesh, Banafshe; Tabatabaei, Seyyed Mohammad Taghi Hosseini; Vahedi, Habib; Hosseinzadeh, Azam; Pazoki-Toroudi, HamidReza; Rashidian, Amir

2016-10-01

This study compared the possible protective effects of silymarin and melatonin against gentamicin (GEN)-induced nephrotoxicity in rats. Rats were allocated to 6 groups: Group I, control group; Groups II and III, administered with silymarin or melatonin; Group IV, injected with GEN; and Groups V and VI, administered with silymarin or melatonin, and then injected with GEN. Compared with the rats in the control group, all rats injected with GEN significantly presented elevated levels of serum creatinine and urea that was accompanied by an increase in relative kidney weight, increase in renal reactive oxygen species (ROS) and malondialdehyde (MDA) levels, and reduction in renal glutathione (GSH) level and superoxide dismutase (SOD) activity. Silymarin and melatonin pretreatment significantly lowered the elevated serum urea and creatinine concentration, kidney weight, and renal ROS and MDA levels. In addition, silymarin and melatonin significantly enhanced renal GSH level and SOD activity. This study indicates that silymarin and melatonin can attenuate renal injury in rats treated with GEN possibly by reducing the ROS level. © The Author(s) 2015.

Skylab experiment M-171 'Metabolic Activity' - Results of the first manned mission

NASA Technical Reports Server (NTRS)

Michel, E. L.; Rummel, J. A.; Sawin, C. F.

1975-01-01

The experiment was performed to ascertain whether man's ability to perform mechanical work would be altered as a result of exposure to the weightless environment. Skylab II crewmen were exercised on a bicycle ergometer at loads approximating 25%, 50%, and 75% of their maximum oxygen uptake while their physiological responses were monitored. The results of these tests indicate that the crewmen had no significant decrement in their response to exercise during their exposure to zero gravity. Immediately postflight, however, all crewmen demonstrated an inability to perform the programmed exercise with the same metabolic effectiveness as they did both preflight and inflight. The most significant changes were elevated heart rates for the same work load and oxygen consumption (decreased oxygen pulse), decreased stroke volume, and decreased cardiac output at the same oxygen consumption level. It is apparent that the changes occurred inflight, but did not manifest themselves until the crewmen attempted to readapt to the 1-G environment.

Improved accuracy of methemoglobin detection by pulse CO-oximetry during hypoxia.

PubMed

Feiner, John R; Bickler, Philip E

2010-11-01

Methemoglobin in the blood cannot be detected by conventional pulse oximetry and may bias the oximeter's estimate (Spo(2)) of the true arterial functional oxygen saturation (Sao(2)). A recently introduced "pulse CO-oximeter" (Masimo Rainbow SET® Radical-7) that measures SpMet, a noninvasive measurement of the percentage of methemoglobin in arterial blood (%MetHb), was shown to read spuriously high values during hypoxia. In this study we sought to determine whether the manufacturer's modifications have improved the device's ability to detect and accurately measure methemoglobin and deoxyhemoglobin simultaneously. Twelve healthy adult volunteer subjects were fitted with sensors on the middle finger of each hand, and a radial arterial catheter was placed for blood sampling. Intravenous administration of ∼300 mg of sodium nitrite elevated subjects' methemoglobin levels to a 7% to 11% target level, and hypoxia was induced to different levels of Sao(2) (70% to 100%) by varying fractional inspired oxygen. Pulse CO-oximeter readings were compared with arterial blood values measured with a Radiometer ABL800 FLEX multi-wavelength oximeter. Pulse CO-oximeter methemoglobin reading performance was analyzed by the bias (SpMet-%MetHb), and by observing the incidence of meaningful reading errors and predictive value at the various hypoxia levels. Spo(2) bias (Spo(2)--Sao(2)), precision, and root-mean-square error were evaluated during conditions of elevated methemoglobin. Observations spanned 74% to 100% Sao(2) and 0.4% to 14.4% methemoglobin with 307 blood draws and 602 values from the 2 oximeters. Masimo methemoglobin reading bias and precision over the full Sao(2) span was 0.16% and 0.83%, respectively, and was similar across the span. Masimo Spo(2) readings were biased -1.93% across the 70% to 100% Sao(2) range. The Rainbow's methemoglobin readings are acceptably accurate over an oxygen saturation range of 74%-100% and a methemoglobin range of 0%-14%.

In Vitro Cytotoxic Potential of Afghanistan Sand Extract

DTIC Science & Technology

2013-02-05

significant reduction in total antioxidant capacity ( TAC ) with an elevation of reactive oxygen species (ROS). However, N-acetyl cysteine (NAC...The brain is vulnerable to oxidative stress damage because of its high energy use, low levels of endogenous scavengers (e.g., vitamin C, catalase...Zhang et al., 2009; Prabhakaran et al., 2009). Cells were cultured on poly-l-lysine-pre- coated plates in Dulbecco’s Modified Eagle Medium (DMEM

Acetone photophysics at 282 nm excitation at elevated pressure and temperature. II: Fluorescence modeling

NASA Astrophysics Data System (ADS)

Hartwig, Jason; Raju, Mandhapati; Sung, Chih-Jen

2017-07-01

This is the second in a series of two papers that presents an updated fluorescence model and compares with the new experimental data reported in the first paper, as well as the available literature data, to extend the range of acetone photophysics to elevated pressure and temperature conditions. This work elucidates the complete acetone photophysical model in terms of each and every competing radiative and non-radiative rate. The acetone fluorescence model is then thoroughly examined and optimized based on disparity with recently conducted elevated pressure and temperature photophysical calibration experiments. The current work offers insight into the competition between non-radiative and vibrational energy decay rates at elevated temperature and pressure and proposes a global optimization of model parameters from the photophysical model developed by Thurber (Acetone Laser-Induced Fluorescence for Temperature and Multiparameter Imaging in Gaseous Flows. PhD thesis, Stanford University Mechanical Engineering Department, 1999). The collisional constants of proportionality, which govern vibrational relaxation, are shown to be temperature dependent at elevated pressures. A new oxygen quenching rate is proposed which takes into account collisions with oxygen as well as the oxygen-assisted intersystem crossing component. Additionally, global trends in ketone photophysics are presented and discussed.

Weight Loss by Ppc-1, a Novel Small Molecule Mitochondrial Uncoupler Derived from Slime Mold

PubMed Central

Suzuki, Toshiyuki; Kikuchi, Haruhisa; Ogura, Masato; Homma, Miwako K.; Oshima, Yoshiteru; Homma, Yoshimi

2015-01-01

Mitochondria play a key role in diverse processes including ATP synthesis and apoptosis. Mitochondrial function can be studied using inhibitors of respiration, and new agents are valuable for discovering novel mechanisms involved in mitochondrial regulation. Here, we screened small molecules derived from slime molds and other microorganisms for their effects on mitochondrial oxygen consumption. We identified Ppc-1 as a novel molecule which stimulates oxygen consumption without adverse effects on ATP production. The kinetic behavior of Ppc-1 suggests its function as a mitochondrial uncoupler. Serial administration of Ppc-1 into mice suppressed weight gain with no abnormal effects on liver or kidney tissues, and no evidence of tumor formation. Serum fatty acid levels were significantly elevated in mice treated with Ppc-1, while body fat content remained low. After a single administration, Ppc-1 distributes into various tissues of individual animals at low levels. Ppc-1 stimulates adipocytes in culture to release fatty acids, which might explain the elevated serum fatty acids in Ppc-1-treated mice. The results suggest that Ppc-1 is a unique mitochondrial regulator which will be a valuable tool for mitochondrial research as well as the development of new drugs to treat obesity. PMID:25668511

Brain stem activity changes associated with restored sympathetic drive following CPAP treatment in OSA subjects: a longitudinal investigation

PubMed Central

Lundblad, Linda C.; Fatouleh, Rania H.; McKenzie, David K.; Macefield, Vaughan G.

2015-01-01

Obstructive sleep apnea (OSA) is associated with significantly elevated muscle sympathetic nerve activity (MSNA), leading to hypertension and increased cardiovascular morbidity. Although little is known about the mechanisms responsible for the sympathoexcitation, we have recently shown that the elevated MSNA in OSA is associated with altered neural processing in various brain stem sites, including the dorsolateral pons, rostral ventrolateral medulla, medullary raphe, and midbrain. Given the risk associated with elevated MSNA, we aimed to determine if treatment of OSA with continuous positive airway pressure (CPAP) would reduce the elevated MSNA and reverse the brain stem functional changes associated with the elevated MSNA. We performed concurrent recordings of MSNA and blood oxygen level-dependent (BOLD) signal intensity of the brain stem, using high-resolution functional magnetic resonance imaging, in 15 controls and 13 subjects with OSA, before and after 6 mo CPAP treatment. As expected, 6 mo of CPAP treatment significantly reduced MSNA in subjects with OSA, from 54 ± 4 to 23 ± 3 bursts/min and from 77 ± 7 to 36 ± 3 bursts/100 heart beats. Importantly, we found that MSNA-coupled changes in BOLD signal intensity within the dorsolateral pons, medullary raphe, and rostral ventrolateral medulla returned to control levels. That is, CPAP treatment completely reversed brain stem functional changes associated with elevated MSNA in untreated OSA subjects. These data highlight the effectiveness of CPAP treatment in reducing one of the most significant health issues associated with OSA, that is, elevated MSNA and its associated elevated morbidity. PMID:25995345

Brain stem activity changes associated with restored sympathetic drive following CPAP treatment in OSA subjects: a longitudinal investigation.

PubMed

Lundblad, Linda C; Fatouleh, Rania H; McKenzie, David K; Macefield, Vaughan G; Henderson, Luke A

2015-08-01

Obstructive sleep apnea (OSA) is associated with significantly elevated muscle sympathetic nerve activity (MSNA), leading to hypertension and increased cardiovascular morbidity. Although little is known about the mechanisms responsible for the sympathoexcitation, we have recently shown that the elevated MSNA in OSA is associated with altered neural processing in various brain stem sites, including the dorsolateral pons, rostral ventrolateral medulla, medullary raphe, and midbrain. Given the risk associated with elevated MSNA, we aimed to determine if treatment of OSA with continuous positive airway pressure (CPAP) would reduce the elevated MSNA and reverse the brain stem functional changes associated with the elevated MSNA. We performed concurrent recordings of MSNA and blood oxygen level-dependent (BOLD) signal intensity of the brain stem, using high-resolution functional magnetic resonance imaging, in 15 controls and 13 subjects with OSA, before and after 6 mo CPAP treatment. As expected, 6 mo of CPAP treatment significantly reduced MSNA in subjects with OSA, from 54 ± 4 to 23 ± 3 bursts/min and from 77 ± 7 to 36 ± 3 bursts/100 heart beats. Importantly, we found that MSNA-coupled changes in BOLD signal intensity within the dorsolateral pons, medullary raphe, and rostral ventrolateral medulla returned to control levels. That is, CPAP treatment completely reversed brain stem functional changes associated with elevated MSNA in untreated OSA subjects. These data highlight the effectiveness of CPAP treatment in reducing one of the most significant health issues associated with OSA, that is, elevated MSNA and its associated elevated morbidity. Copyright © 2015 the American Physiological Society.

Intraoperative Oxygen Consumption During Liver Transplantation.

PubMed

Shibata, M; Matsusaki, T; Kaku, R; Umeda, Y; Yagi, T; Morimatsu, H

2015-12-01

The aim of this study was to investigate the changes in oxygen consumption during liver transplantation and to examine the relationship between intraoperatively elevated systemic oxygen consumption and postoperative liver function. This study was performed in 33 adult patients undergoing liver transplantation between September 2011 and March 2014. We measured intraoperative oxygen consumption through the use of indirect calorimetry, preoperative and intraoperative data, liver function tests, and postoperative complications and outcomes. The mean age of patients was 52 ± 9.7 years; 14 (42%) of them were women. Average Model for End-Stage Liver Disease scores were 20 ± 8.9. Oxygen consumption significantly increased after reperfusion from 172 ± 30 mL/min during the anhepatic phase to 209 ± 30 mL/min (P < .0001). We divided patients into 2 groups according to the increase in oxygen consumption after reperfusion (oxygen consumption after reperfusion minus anhepatic phase oxygen consumption: 40 mL/min increase as cutoff). The higher consumption group had a longer cold ischemia time and higher postoperative aspartate aminotransferase and alanine aminotransferase levels as compared with the lower oxygen consumption group. There were no statistically significant differences in major postoperative complications, but the higher oxygen consumption group tended to have shorter hospital stays than the lower consumption group (58 versus 95 days). We have demonstrated that oxygen consumption significantly increased after reperfusion. Furthermore, this increased oxygen consumption was associated with a longer cold ischemia time and shorter hospital stays. Copyright © 2015 Elsevier Inc. All rights reserved.

Atomic-Level Co3O4 Layer Stabilized by Metallic Cobalt Nanoparticles: A Highly Active and Stable Electrocatalyst for Oxygen Reduction.

PubMed

Liu, Min; Liu, Jingjun; Li, Zhilin; Wang, Feng

2018-02-28

Developing atomic-level transition oxides may be one of the most promising ways for providing ultrahigh electrocatalytic performance for oxygen reduction reaction (ORR), compared with their bulk counterparts. In this article, we developed a set of atomically thick Co 3 O 4 layers covered on Co nanoparticles through partial reduction of Co 3 O 4 nanoparticles using melamine as a reductive additive at an elevated temperature. Compared with the original Co 3 O 4 nanoparticles, the synthesized Co 3 O 4 with a thickness of 1.1 nm exhibits remarkably enhanced ORR activity and durability, which are even higher than those obtained by a commercial Pt/C in an alkaline environment. The superior activity can be attributed to the unique physical and chemical structures of the atomic-level oxide featuring the narrowed band gap and decreased work function, caused by the escaped lattice oxygen and the enriched coordination-unsaturated Co 2+ in this atomic layer. Besides, the outstanding durability of the catalyst can result from the chemically epitaxial deposition of the Co 3 O 4 on the cobalt surface. Therefore, the proposed synthetic strategy may offer a smart way to develop other atomic-level transition metals with high electrocatalytic activity and stability for energy conversion and storage devices.

Cocaine- and amphetamine-regulated transcript peptide increases mitochondrial respiratory chain complex II activity and protects against oxygen-glucose deprivation in neurons.

PubMed

Sha, Dujuan; Wang, Luna; Zhang, Jun; Qian, Lai; Li, Qiming; Li, Jin; Qian, Jian; Gu, Shuangshuang; Han, Ling; Xu, Peng; Xu, Yun

2014-09-25

The mechanisms of ischemic stroke, a main cause of disability and death, are complicated. Ischemic stroke results from the interaction of various factors including oxidative stress, a key pathological mechanism that plays an important role during the acute stage of ischemic brain injury. This study demonstrated that cocaine- and amphetamine-regulated transcript (CART) peptide, specifically CART55-102, increased the survival rate, but decreased the mortality of neurons exposed to oxygen-glucose deprivation (OGD), in a dose-dependent manner. The above-mentioned effects of CART55-102 were most significant at 0.4nM. These results indicated that CART55-102 suppressed neurotoxicity and enhanced neuronal survival after oxygen-glucose deprivation. CART55-102 (0.4nM) significantly diminished reactive oxygen species levels and markedly increased the activity of mitochondrial respiratory chain complex II in oxygen-glucose deprived neurons. In summary, CART55-102 suppressed oxidative stress in oxygen-glucose deprived neurons, possibly through elevating the activity of mitochondrial respiratory chain complex II. This result provides evidence for the development of CART55-102 as an antioxidant drug. Copyright © 2014 Elsevier B.V. All rights reserved.

Physiological plasticity of cardiorespiratory function in a eurythermal marine teleost, the longjaw mudsucker, Gillichthys mirabilis.

PubMed

Jayasundara, Nishad; Somero, George N

2013-06-01

An insufficient supply of oxygen under thermal stress is thought to define thermal optima and tolerance limits in teleost fish. When under thermal stress, cardiac function plays a crucial role in sustaining adequate oxygen supply for respiring tissues. Thus, adaptive phenotypic plasticity of cardiac performance may be critical for modifying thermal limits during temperature acclimation. Here we investigated effects of temperature acclimation on oxygen consumption, cardiac function and blood oxygen carrying capacity of a eurythermal goby fish, Gillichthys mirabilis, acclimated to 9, 19 and 26°C for 4 weeks. Acclimation did not alter resting metabolic rates or heart rates; no compensation of rates was observed at acclimation temperatures. However, under an acute heat ramp, warm-acclimated fish exhibited greater heat tolerance (CTmax=33.3, 37.1 and 38.9°C for 9°C-, 19°C- and 26°C-acclimated fish, respectively) and higher cardiac arrhythmia temperatures compared with 9°C-acclimated fish. Heart rates measured under an acute heat stress every week during 28 days of acclimation suggested that both maximum heart rates and temperature at onset of maximum heart rates changed over time with acclimation. Hemoglobin levels increased with acclimation temperature, from 35 g l(-1) in 9°C-acclimated fish to 60-80 g l(-1) in 19°C- and 26°C-acclimated fish. Oxygen consumption rates during recovery from acute heat stress showed post-stress elevation in 26°C-acclimated fish. These data, coupled with elevated resting metabolic rates and heart rates at warm temperatures, suggest a high energetic cost associated with warm acclimation in G. mirabilis. Furthermore, acclimatory capacity appears to be optimized at 19°C, a temperature shown by behavioral studies to be close to the species' preferred temperature.

Influence of high altitude on cerebral blood flow and fuel utilization during exercise and recovery.

PubMed

Smith, K J; MacLeod, D; Willie, C K; Lewis, N C S; Hoiland, R L; Ikeda, K; Tymko, M M; Donnelly, J; Day, T A; MacLeod, N; Lucas, S J E; Ainslie, P N

2014-12-15

We examined the hypotheses that: (1) during incremental exercise and recovery following 4-6 days at high altitude (HA) global cerebral blood flow (gCBF) increases to preserve cerebral oxygen delivery (CDO2) in excess of that required by an increasing cerebral metabolic rate of oxygen ( CM RO2); (2) the trans-cerebral exchange of oxygen vs. carbohydrates (OCI; carbohydrates = glucose + ½lactate) would be similar during exercise and recovery at HA and sea level (SL). Global CBF, intra-cranial arterial blood velocities, extra-cranial blood flows, and arterial-jugular venous substrate differences were measured during progressive steady-state exercise (20, 40, 60, 80, 100% maximum workload (Wmax)) and through 30 min of recovery. Measurements (n = 8) were made at SL and following partial acclimatization to 5050 m. At HA, absolute Wmax was reduced by ∼50%. During submaximal exercise workloads (20-60% Wmax), despite an elevated absolute gCBF (∼20%, P < 0.05) the relative increases in gCBF were not different at HA and SL. In contrast, gCBF was elevated at HA compared with SL during 80 and 100% Wmax and recovery. Notwithstanding a maintained CDO2 and elevated absolute CM RO2 at HA compared with SL, the relative increase in CM RO2 was similar during 20-80% Wmax but half that of the SL response (i.e. 17 vs. 27%; P < 0.05 vs. SL) at 100% Wmax. The OCI was reduced at HA compared with SL during 20, 40, and 60% Wmax but comparable at 80 and 100% Wmax. At HA, OCI returned almost immediately to baseline values during recovery, whereas at SL it remained below baseline. In conclusion, the elevations in gCBF during exercise and recovery at HA serve to maintain CDO2. Despite adequate CDO2 at HA the brain appears to increase non-oxidative metabolism during exercise and recovery. © 2014 The Authors. The Journal of Physiology © 2014 The Physiological Society.

Influence of high altitude on cerebral blood flow and fuel utilization during exercise and recovery

PubMed Central

Smith, K J; MacLeod, D; Willie, C K; Lewis, N C S; Hoiland, R L; Ikeda, K; Tymko, M M; Donnelly, J; Day, T A; MacLeod, N; Lucas, S J E; Ainslie, P N

2014-01-01

We examined the hypotheses that: (1) during incremental exercise and recovery following 4–6 days at high altitude (HA) global cerebral blood flow (gCBF) increases to preserve cerebral oxygen delivery () in excess of that required by an increasing cerebral metabolic rate of oxygen (); (2) the trans-cerebral exchange of oxygen vs. carbohydrates (OCI; carbohydrates = glucose + ½lactate) would be similar during exercise and recovery at HA and sea level (SL). Global CBF, intra-cranial arterial blood velocities, extra-cranial blood flows, and arterial–jugular venous substrate differences were measured during progressive steady-state exercise (20, 40, 60, 80, 100% maximum workload (Wmax)) and through 30 min of recovery. Measurements (n = 8) were made at SL and following partial acclimatization to 5050 m. At HA, absolute Wmax was reduced by ∼50%. During submaximal exercise workloads (20–60% Wmax), despite an elevated absolute gCBF (∼20%, P < 0.05) the relative increases in gCBF were not different at HA and SL. In contrast, gCBF was elevated at HA compared with SL during 80 and 100% Wmax and recovery. Notwithstanding a maintained and elevated absolute at HA compared with SL, the relative increase in was similar during 20–80% Wmax but half that of the SL response (i.e. 17 vs. 27%; P < 0.05 vs. SL) at 100% Wmax. The OCI was reduced at HA compared with SL during 20, 40, and 60% Wmax but comparable at 80 and 100% Wmax. At HA, OCI returned almost immediately to baseline values during recovery, whereas at SL it remained below baseline. In conclusion, the elevations in gCBF during exercise and recovery at HA serve to maintain . Despite adequate at HA the brain appears to increase non-oxidative metabolism during exercise and recovery. PMID:25362150

Lake Roosevelt Fisheries Evaluation Program; Limnological and Fisheries Monitoring, Annual Report 2000.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Chuck; Scofield, Ben; Pavlik, Deanne

2003-03-01

A slightly dryer than normal year yielded flows in Lake Roosevelt that were essentially equal to the past ten year average. Annual mean inflow and outflow were 3,160.3 m3/s and 3,063.4 m3/s respectively. Mean reservoir elevation was 387.2 m above sea level at the Grand Coulee Dam forebay. The forebay elevation was below the mean elevation for a total of 168 days. During the first half of the 2000 forebay elevation changed at a rate of 0.121 m/d and during the last half changed at a rate of 0.208 m/d. The higher rate of elevation change earlier in the yearmore » is due to the drawdown to accommodate spring runoff. Mean annual water retention time was 40 days. Annual mean total dissolved gas was 108%. Total dissolved gas was greatest at upriver locations (110% = US/Canada Border annual mean) and decreased moving toward Grand Coulee Dam (106% = Grand Coulee Dam Forebay annual mean). Total dissolved gas was greatest in May (122% reservoir wide monthly mean). Gas bubble trauma was observed in 16 fish primarily largescale suckers and was low in severity. Reservoir wide mean temperatures were greatest in August (19.5 C) and lowest in January (5.5 C). The Spokane River and Sanpoil River Arms experienced higher temperatures than the mainstem reservoir. Brief stratification was observed at the Sanpoil River shore location in July. Warm water temperatures in the Spokane Arm contributed to low dissolved oxygen concentrations in August (2.6 mg/L at 33 m). However, decomposition of summer algal biomass was likely the main cause of depressed dissolved oxygen concentrations. Otherwise, dissolved oxygen profiles were relatively uniform throughout the water column across other sampling locations. Annual mean Secchi depth throughout the reservoir was 5.7 m. Nutrient concentrations were generally low, however, annual mean total phosphorus (0.016 mg/L) was in the mesotrophic range. Annual mean total nitrogen was in the meso-oligotrophic range. Total nitrogen to total phosphorus ratios were large (31:1 annual mean) likely indicating phosphorus limitations to phytoplankton.« less

The cumulative influence of hyperoxia and hypercapnia on blood oxygenation and R2*

PubMed Central

Faraco, Carlos C; Strother, Megan K; Siero, Jeroen CW; Arteaga, Daniel F; Scott, Allison O; Jordan, Lori C; Donahue, Manus J

2015-01-01

Cerebrovascular reactivity (CVR)-weighted blood-oxygenation-level-dependent magnetic resonance imaging (BOLD-MRI) experiments are frequently used in conjunction with hyperoxia. Owing to complex interactions between hyperoxia and hypercapnia, quantitative effects of these gas mixtures on BOLD responses, blood and tissue R2*, and blood oxygenation are incompletely understood. Here we performed BOLD imaging (3 T; TE/TR=35/2,000 ms; spatial resolution=3 × 3 × 3.5 mm3) in healthy volunteers (n=12; age=29±4.1 years) breathing (i) room air (RA), (ii) normocapnic–hyperoxia (95% O2/5% N2, HO), (iii) hypercapnic–normoxia (5% CO2/21% O2/74% N2, HC-NO), and (iv) hypercapnic–hyperoxia (5% CO2/95% O2, HC-HO). For HC-HO, experiments were performed with separate RA and HO baselines to control for changes in O2. T2-relaxation-under-spin-tagging MRI was used to calculate basal venous oxygenation. Signal changes were quantified and established hemodynamic models were applied to quantify vasoactive blood oxygenation, blood–water R2*, and tissue–water R2*. In the cortex, fractional BOLD changes (stimulus/baseline) were HO/RA=0.011±0.007; HC-NO/RA=0.014±0.004; HC-HO/HO=0.020±0.008; and HC-HO/RA=0.035±0.010; for the measured basal venous oxygenation level of 0.632, this led to venous blood oxygenation levels of 0.660 (HO), 0.665 (HC-NO), and 0.712 (HC-HO). Interleaving a HC-HO stimulus with HO baseline provided a smaller but significantly elevated BOLD response compared with a HC-NO stimulus. Results provide an outline for how blood oxygenation differs for several gas stimuli and provides quantitative information on how hypercapnic BOLD CVR and R2* are altered during hyperoxia. PMID:26174329

[Several indicators of tissue oxygen during modeling of extravehicular activity of man].

PubMed

Lan'shina, O E; Loginov, V A; Akinfiev, A V; Kovalenko, E A

1995-01-01

Investigations of tissue oxygen indices during simulation of extravehicular activity (EVA) of cosmonauts demonstrated that breathing pure oxygen at approximately 280 mmHg elevates oxygen tension in capillary blood, and capillary-tissue gradient during physical work. Physical work alone stimulates tissue oxygenation due to, apparently, intensification of the processes of oxidative phosphorylation. The observed shifts in oxygen status reverse significantly within the first 5 min after completion of the experiment.

Calcium Signaling Is Involved in Cadmium-Induced Neuronal Apoptosis via Induction of Reactive Oxygen Species and Activation of MAPK/mTOR Network

PubMed Central

Luo, Yan; Chen, Zi; Liu, Lei; Zhou, Hongyu; Chen, Wenxing; Shen, Tao; Han, Xiuzhen; Chen, Long; Huang, Shile

2011-01-01

Cadmium (Cd), a toxic environmental contaminant, induces oxidative stress, leading to neurodegenerative disorders. Recently we have demonstrated that Cd induces neuronal apoptosis in part by activation of the mitogen-activated protein kineses (MAPK) and mammalian target of rapamycin (mTOR) pathways. However, the underlying mechanism remains elusive. Here we show that Cd elevated intracellular calcium ion ([Ca2+]i) level in PC12, SH-SY5Y cells and primary murine neurons. BAPTA/AM, an intracellular Ca2+ chelator, abolished Cd-induced [Ca2+]i elevation, and blocked Cd activation of MAKPs including extracellular signal-regulated kinase 1/2 (Erk1/2), c-Jun N-terminal kinase (JNK) and p38, and mTOR-mediated signaling pathways, as well as cell death. Pretreatment with the extracellular Ca2+ chelator EGTA also prevented Cd-induced [Ca2+]i elevation, MAPK/mTOR activation, as well as cell death, suggesting that Cd-induced extracellular Ca2+ influx plays a critical role in contributing to neuronal apoptosis. In addition, calmodulin (CaM) antagonist trifluoperazine (TFP) or silencing CaM attenuated the effects of Cd on MAPK/mTOR activation and cell death. Furthermore, Cd-induced [Ca2+]i elevation or CaM activation resulted in induction of reactive oxygen species (ROS). Pretreatment with BAPTA/AM, EGTA or TFP attenuated Cd-induced ROS and cleavage of caspase-3 in the neuronal cells. Our findings indicate that Cd elevates [Ca2+]i, which induces ROS and activates MAPK and mTOR pathways, leading to neuronal apoptosis. The results suggest that regulation of Cd-disrupted [Ca2+]i homeostasis may be a new strategy for prevention of Cd-induced neurodegenerative diseases. PMID:21544200

Sphingosine-1-phosphate promotes erythrocyte glycolysis and oxygen release for adaptation to high-altitude hypoxia

PubMed Central

Sun, Kaiqi; Zhang, Yujin; D'Alessandro, Angelo; Nemkov, Travis; Song, Anren; Wu, Hongyu; Liu, Hong; Adebiyi, Morayo; Huang, Aji; Wen, Yuan E.; Bogdanov, Mikhail V.; Vila, Alejandro; O'Brien, John; Kellems, Rodney E.; Dowhan, William; Subudhi, Andrew W.; Jameson-Van Houten, Sonja; Julian, Colleen G.; Lovering, Andrew T.; Safo, Martin; Hansen, Kirk C.; Roach, Robert C.; Xia, Yang

2016-01-01

Sphingosine-1-phosphate (S1P) is a bioactive signalling lipid highly enriched in mature erythrocytes, with unknown functions pertaining to erythrocyte physiology. Here by employing nonbiased high-throughput metabolomic profiling, we show that erythrocyte S1P levels rapidly increase in 21 healthy lowland volunteers at 5,260 m altitude on day 1 and continue increasing to 16 days with concurrently elevated erythrocyte sphingonisne kinase 1 (Sphk1) activity and haemoglobin (Hb) oxygen (O2) release capacity. Mouse genetic studies show that elevated erythrocyte Sphk1-induced S1P protects against tissue hypoxia by inducing O2 release. Mechanistically, we show that intracellular S1P promotes deoxygenated Hb anchoring to the membrane, enhances the release of membrane-bound glycolytic enzymes to the cytosol, induces glycolysis and thus the production of 2,3-bisphosphoglycerate (2,3-BPG), an erythrocyte-specific glycolytic intermediate, which facilitates O2 release. Altogether, we reveal S1P as an intracellular hypoxia-responsive biolipid promoting erythrocyte glycolysis, O2 delivery and thus new therapeutic opportunities to counteract tissue hypoxia. PMID:27417539

P53 alters the cytotoxicity and genotoxicity for oxidized graphene in human B-lymphoblastoid cells

NASA Astrophysics Data System (ADS)

Petibone, Dayton Matthew

Widespread use of oxidized graphene nanomaterials in industry, medicine, and consumer products raises concern about potential adverse impacts on human health. The p53 tumor suppressor protein is crucial to maintaining cellular and genetic stability to prevent carcinogenesis. Here, we show that oxygen functionalized graphene (f-G) absorption and p53 functional status correlate with cytotoxicity and genotoxicity in human B-lymphoblastoid cells. Trends in f-G absorption by were dose-dependent. Cells with functional p53 exposed to f-G arrested in G0/G1 phase of the cell cycle, suppressed f-G induced reactive oxygen species (ROS), and had elevated apoptosis. While compared to p53 competent cells, the p53 deficient cells exposed to f-G accumulated in S-phase of the cell cycle, had elevated ROS levels, and evaded apoptosis. The f-G genotoxicity was evident as increased loss-of-heterozygosity mutants independent of p53 status, and structural chromosome damage in p53 deficient cells. These findings have broad implications for the safety and efficacy of oxidized graphene nanomaterials in industrial, consumer products and biomedical applications.

Impact of trans-resveratrol-sulfates and -glucuronides on endothelial nitric oxide synthase activity, nitric oxide release and intracellular reactive oxygen species.

PubMed

Ladurner, Angela; Schachner, Daniel; Schueller, Katharina; Pignitter, Marc; Heiss, Elke H; Somoza, Veronika; Dirsch, Verena M

2014-10-17

Resveratrol (3,5,4'-trihydroxy-trans-stilbene) is a polyphenolic natural product mainly present in grape skin, berries and peanuts. In the vasculature resveratrol is thought to boost endothelial function by increasing endothelial nitric oxide synthase (eNOS) expression, by enhancing eNOS activity, and by reduction of reactive oxygen species (ROS) levels. Recent studies show that dietary resveratrol is metabolized in the liver and intestine into resveratrol-sulfate and -glucuronide derivatives questioning the relevance of multiple reported mechanistic in vitro data on resveratrol. In this study, we compare side by side different physiologically relevant resveratrol metabolites (resveratrol sulfates- and -glucuronides) and their parent compound in their influence on eNOS enzyme activity, endothelial NO release, and intracellular ROS levels. In contrast to resveratrol, none of the tested resveratrol metabolites elevated eNOS enzyme activity and endothelial NO release or affected intracellular ROS levels, leaving the possibility that not tested metabolites are active and able to explain in vivo findings.

Effects of oolong tea on plasma antioxidative capacity in mice loaded with restraint stress assessed using the oxygen radical absorbance capacity (ORAC) assay.

PubMed

Kurihara, Hiroshi; Fukami, Harukazu; Asami, Sumio; Toyoda, Yoshiko; Nakai, Masaaki; Shibata, Hiroshi; Yao, Xin-Sheng

2004-07-01

In the present study, we investigated the antioxidative effect of oolong tea in vitro and in vivo using the oxygen radical absorbance capacity (ORAC) assay. An oolong tea extract, catechin and related compounds suppressed the oxidation of fluorescence induced by AAPH in a dose-dependent manner, that is, they prolonged the antioxidant time in vitro. Oral administration of the oolong tea extract to mice treated with restraint stress increased ORAC activity in plasma as compared with a stress control group. The extract also increased plasma vitamin C levels, and there was a good relationship between ORAC activity and the vitamin C level in plasma. The elevation of plasma ORAC and vitamin C level may have been related to the stress-relieving effect of oolong tea. These effects are probably due to the antioxidative properties of the tea. Thus, these findings suggested that oolong tea has beneficial effects on health related to its antioxidative action.

Variation in temperature tolerance among families of Atlantic salmon (Salmo salar) is associated with hypoxia tolerance, ventricle size and myoglobin level.

PubMed

Anttila, Katja; Dhillon, Rashpal S; Boulding, Elizabeth G; Farrell, Anthony P; Glebe, Brian D; Elliott, Jake A K; Wolters, William R; Schulte, Patricia M

2013-04-01

In fishes, performance failure at high temperature is thought to be due to a limitation on oxygen delivery (the theory of oxygen and capacity limited thermal tolerance, OCLTT), which suggests that thermal tolerance and hypoxia tolerance might be functionally associated. Here we examined variation in temperature and hypoxia tolerance among 41 families of Atlantic salmon (Salmo salar), which allowed us to evaluate the association between these two traits. Both temperature and hypoxia tolerance varied significantly among families and there was a significant positive correlation between critical maximum temperature (CTmax) and hypoxia tolerance, supporting the OCLTT concept. At the organ and cellular levels, we also discovered support for the OCLTT concept as relative ventricle mass (RVM) and cardiac myoglobin (Mb) levels both correlated positively with CTmax (R(2)=0.21, P<0.001 and R(2)=0.17, P=0.003, respectively). A large RVM has previously been shown to be associated with high cardiac output, which might facilitate tissue oxygen supply during elevated oxygen demand at high temperatures, while Mb facilitates the oxygen transfer from the blood to tissues, especially during hypoxia. The data presented here demonstrate for the first time that RVM and Mb are correlated with increased upper temperature tolerance in fish. High phenotypic variation between families and greater similarity among full- and half-siblings suggests that there is substantial standing genetic variation in thermal and hypoxia tolerance, which could respond to selection either in aquaculture or in response to anthropogenic stressors such as global climate change.

Microvascular oxygen consumption during sickle cell pain crisis.

PubMed

Rowley, Carol A; Ikeda, Allison K; Seidel, Miles; Anaebere, Tiffany C; Antalek, Matthew D; Seamon, Catherine; Conrey, Anna K; Mendelsohn, Laurel; Nichols, James; Gorbach, Alexander M; Kato, Gregory J; Ackerman, Hans

2014-05-15

Sickle cell disease is an inherited blood disorder characterized by chronic hemolytic anemia and episodic vaso-occlusive pain crises. Vaso-occlusion occurs when deoxygenated hemoglobin S polymerizes and erythrocytes sickle and adhere in the microvasculature, a process dependent on the concentration of hemoglobin S and the rate of deoxygenation, among other factors. We measured oxygen consumption in the thenar eminence during brachial artery occlusion in sickle cell patients and healthy individuals. Microvascular oxygen consumption was greater in sickle cell patients than in healthy individuals (median [interquartile range]; sickle cell: 0.91 [0.75-1.07] vs healthy: 0.75 [0.62-0.94] -ΔHbO2/min, P < .05) and was elevated further during acute pain crisis (crisis: 1.10 [0.78-1.30] vs recovered: 0.88 [0.76-1.03] -ΔHbO2/min, P < .05). Increased microvascular oxygen consumption during pain crisis could affect the local oxygen saturation of hemoglobin when oxygen delivery is limiting. Identifying the mechanisms of elevated oxygen consumption during pain crisis might lead to the development of new therapeutic interventions. This trial was registered at www.clinicaltrials.gov as #NCT01568710.

Understanding and Controlling Sialylation in a CHO Fc-Fusion Process

PubMed Central

Lewis, Amanda M.; Croughan, William D.; Aranibar, Nelly; Lee, Alison G.; Warrack, Bethanne; Abu-Absi, Nicholas R.; Patel, Rutva; Drew, Barry; Borys, Michael C.; Reily, Michael D.; Li, Zheng Jian

2016-01-01

A Chinese hamster ovary (CHO) bioprocess, where the product is a sialylated Fc-fusion protein, was operated at pilot and manufacturing scale and significant variation of sialylation level was observed. In order to more tightly control glycosylation profiles, we sought to identify the cause of variability. Untargeted metabolomics and transcriptomics methods were applied to select samples from the large scale runs. Lower sialylation was correlated with elevated mannose levels, a shift in glucose metabolism, and increased oxidative stress response. Using a 5-L scale model operated with a reduced dissolved oxygen set point, we were able to reproduce the phenotypic profiles observed at manufacturing scale including lower sialylation, higher lactate and lower ammonia levels. Targeted transcriptomics and metabolomics confirmed that reduced oxygen levels resulted in increased mannose levels, a shift towards glycolysis, and increased oxidative stress response similar to the manufacturing scale. Finally, we propose a biological mechanism linking large scale operation and sialylation variation. Oxidative stress results from gas transfer limitations at large scale and the presence of oxygen dead-zones inducing upregulation of glycolysis and mannose biosynthesis, and downregulation of hexosamine biosynthesis and acetyl-CoA formation. The lower flux through the hexosamine pathway and reduced intracellular pools of acetyl-CoA led to reduced formation of N-acetylglucosamine and N-acetylneuraminic acid, both key building blocks of N-glycan structures. This study reports for the first time a link between oxidative stress and mammalian protein sialyation. In this study, process, analytical, metabolomic, and transcriptomic data at manufacturing, pilot, and laboratory scales were taken together to develop a systems level understanding of the process and identify oxygen limitation as the root cause of glycosylation variability. PMID:27310468

Daily nursing care on patients undergoing venous-venous extracorporeal membrane oxygenation: a challenging procedure!

PubMed

Redaelli, Sara; Zanella, Alberto; Milan, Manuela; Isgrò, Stefano; Lucchini, Alberto; Pesenti, Antonio; Patroniti, Nicolò

2016-12-01

Daily nursing in critical care patients may alter vital parameters, especially in the most critically ill patients. The aim of our study was to evaluate feasibility and safety of daily nursing on patients undergoing venous-venous extracorporeal membrane oxygenation (vv-ECMO) for severe respiratory failure. Daily nursing was performed following defined phases (sponge bath, elevation with scooping stretcher, change position of endotracheal tube, dressing replacement). We recorded physiological and ECMO parameters before and during daily nursing in 5 patients for several days (total: 25 daily nursing) and adverse events: desaturation, hypertension, reduction of mixed venous oxygen saturation, arterial oxygen saturation or ECMO blood flow and elevation in minute ventilation. Sedative drug dosage and additional bolus were recorded. Daily nursing was performed in 92 % of cases (23/25), with a minimum of two adverse events per daily nursing. Hypertension and tachycardia were mostly recorded at the beginning, while desaturation, reduction in mixed venous oxygen saturation and blood flow were recorded during elevation with scooping stretcher. Increase in minute ventilation was frequent in spontaneous breathing patients. Additional bolus of sedation was required before and/or during nursing. Daily nursing significantly alters physiologic parameters; thus, it should be performed only when physicians are readily available to treat adverse events.

Water Resources Data--Kansas, Water Year 2003

USGS Publications Warehouse

Putnam, J.E.; Schneider, D.R.

2004-01-01

Water-resources data for the 2003 water year for Kansas consist of records of stage, discharge, and water quality of streams; elevation and contents of lakes and reservoirs; and water levels of ground-water wells. This report contains records for water discharge at 148 complete-record gaging stations; elevation and contents at 17 lakes and reservoirs; water-quality records at 2 precipitation stations, water-level data at 12 observation wells; and records of specific conductance, pH, water temperature, dissolved oxygen, and turbidity at 11 gaging stations and 2 lakes with water-quality monitors. Also included are discharge data for 27 high-flow partial-record stations, miscellaneous onsite water-quality data collected at 138 stations, and suspended-sediment concentration for 11 stations. These data represent that part of the National Water Information System collected by the U.S. Geological Survey in cooperation with local, State, and Federal agencies in Kansas.

Exercise-induced myalgia may limit the cardiovascular benefits of statins.

PubMed

Opie, Lionel H

2013-12-01

The positive health benefits of statins extend beyond the cardiovascular and include increased flow mediated dilation, decreased atrial fibrillation, modest antihypertensive effects and reduced risks of malignancies. Prominent among the statin side-effects are myalgia and muscular weakness, which may be associated with a rise in circulating creatine kinase values. In increasing severity and decreasing incidence, the statin-induced muscle related conditions are myalgia, myopathy with elevated creatine kinase (CK) levels with or without symptoms, and rhabdomyolysis. Statin use may increase CK levels without decreasing average muscle strength or exercise performance. In one large study, only about 2 % had myalgia that could be attributed to statin use. A novel current hypothesis is that statins optimize cardiac mitochondrial function but impair the vulnerable skeletal muscle by inducing different levels of reactive oxygen species (ROS) in these two sites. In an important observational study, both statins and exercise reduced the adverse outcomes of cardiovascular disease, and the effects were additive. The major unresolved problem is that either can cause muscular symptoms with elevation of blood creatine kinase levels. There is, as yet, no clearly defined outcomes based policy to deal with such symptoms from use of either statins or exercise or both. A reasonable practical approach is to assess the creatine kinase levels, and if elevated to reduce the statin dose or the intensity of exercise.

Impact of long-term moderate hypercapnia and elevated temperature on the energy budget of isolated gills of Atlantic cod (Gadus morhua).

PubMed

Kreiss, Cornelia M; Michael, Katharina; Bock, Christian; Lucassen, Magnus; Pörtner, Hans-O

2015-04-01

Effects of severe hypercapnia have been extensively studied in marine fishes, while knowledge on the impacts of moderately elevated CO2 levels and their combination with warming is scarce. Here we investigate ion regulation mechanisms and energy budget in gills from Atlantic cod acclimated long-term to elevated PCO2 levels (2500 μatm) and temperature (18°C). Isolated perfused gill preparations were established to determine gill thermal plasticity during acute exposures (10-22°C) and in vivo costs of Na(+)/K(+)-ATPase activity, protein and RNA synthesis. Maximum enzyme capacities of F1Fo-ATPase, H(+)-ATPase and Na(+)/K(+)-ATPase were measured in vitro in crude gill homogenates. After whole animal acclimation to elevated PCO2 and/or warming, branchial oxygen consumption responded more strongly to acute temperature change. The fractions of gill respiration allocated to protein and RNA synthesis remained unchanged. In gills of fish CO2-exposed at both temperatures, energy turnover associated with Na(+)/K(+)-ATPase activity was reduced by 30% below rates of control fish. This contrasted in vitro capacities of Na(+)/K(+)-ATPase, which remained unchanged under elevated CO2 at 10°C, and earlier studies which had found a strong upregulation under severe hypercapnia. F1Fo-ATPase capacities increased in hypercapnic gills at both temperatures, whereas Na(+)/K(+)ATPase and H(+)-ATPase capacities only increased in response to elevated CO2 and warming indicating the absence of thermal compensation under CO2. We conclude that in vivo ion regulatory energy demand is lowered under moderately elevated CO2 levels despite the stronger thermal response of total gill respiration and the upregulation of F1Fo-ATPase. This effect is maintained at elevated temperature. Copyright © 2014 Elsevier Inc. All rights reserved.

Seed storage at elevated partial pressure of oxygen, a fast method for analysing seed ageing under dry conditions

PubMed Central

Groot, S. P. C.; Surki, A. A.; de Vos, R. C. H.; Kodde, J.

2012-01-01

Background and Aims Despite differences in physiology between dry and relative moist seeds, seed ageing tests most often use a temperature and seed moisture level that are higher than during dry storage used in commercial practice and gene banks. This study aimed to test whether seed ageing under dry conditions can be accelerated by storing under high-pressure oxygen. Methods Dry barley (Hordeum vulgare), cabbage (Brassica oleracea), lettuce (Lactuca sativa) and soybean (Glycine max) seeds were stored between 2 and 7 weeks in steel tanks under 18 MPa partial pressure of oxygen. Storage under high-pressure nitrogen gas or under ambient air pressure served as controls. The method was compared with storage at 45 °C after equilibration at 85 % relative humidity and long-term storage at the laboratory bench. Germination behaviour, seedling morphology and tocopherol levels were assessed. Key Results The ageing of the dry seeds was indeed accelerated by storing under high-pressure oxygen. The morphological ageing symptoms of the stored seeds resembled those observed after ageing under long-term dry storage conditions. Barley appeared more tolerant of this storage treatment compared with lettuce and soybean. Less-mature harvested cabbage seeds were more sensitive, as was the case for primed compared with non-primed lettuce seeds. Under high-pressure oxygen storage the tocopherol levels of dry seeds decreased, in a linear way with the decline in seed germination, but remained unchanged in seeds deteriorated during storage at 45 °C after equilibration at 85 % RH. Conclusions Seed storage under high-pressure oxygen offers a novel and relatively fast method to study the physiology and biochemistry of seed ageing at different seed moisture levels and temperatures, including those that are representative of the dry storage conditions as used in gene banks and commercial practice. PMID:22967856

Traffic Lights in Trichodesmium. Regulation of Photosynthesis for Nitrogen Fixation Studied by Chlorophyll Fluorescence Kinetic Microscopy1

PubMed Central

Küpper, Hendrik; Ferimazova, Naila; Šetlík, Ivan; Berman-Frank, Ilana

2004-01-01

We investigated interactions between photosynthesis and nitrogen fixation in the non-heterocystous marine cyanobacterium Trichodesmium IMS101 at the single-cell level by two-dimensional (imaging) microscopic measurements of chlorophyll fluorescence kinetics. Nitrogen fixation was closely associated with the appearance of cells with high basic fluorescence yield (F0), termed bright cells. In cultures aerated with normal air, both nitrogen fixation and bright cells appeared in the middle of the light phase. In cultures aerated with 5% oxygen, both processes occurred at a low level throughout most of the day. Under 50% oxygen, nitrogen fixation commenced at the beginning of the light phase but declined soon afterwards. Rapid reversible switches between fluorescence levels were observed, which indicated that the elevated F0 of the bright cells originates from reversible uncoupling of the photosystem II (PSII) antenna from the PSII reaction center. Two physiologically distinct types of bright cells were observed. Type I had about double F0 compared to the normal F0 in the dark phase and a PSII activity, measured as variable fluorescence (Fv = Fm − F0), similar to normal non-diazotrophic cells. Correlation of type I cells with nitrogen fixation, oxygen concentration, and light suggests that this physiological state is connected to an up-regulation of the Mehler reaction, resulting in oxygen consumption despite functional PSII. Type II cells had more than three times the normal F0 and hardly any PSII activity measurable by variable fluorescence. They did not occur under low-oxygen concentrations, but appeared under high-oxygen levels outside the diazotrophic period, suggesting that this state represents a reaction to oxidative stress not necessarily connected to nitrogen fixation. In addition to the two high-fluorescence states, cells were observed to reversibly enter a low-fluorescence state. This occurred mainly after a cell went through its bright phase and may represent a fluorescence-quenching recovery phase. PMID:15299119

Determination of the Role of Oxygen in Suspected Acute Myocardial Infarction by Biomarkers

ClinicalTrials.gov

2017-12-08

Acute Myocardial Infarction (AMI); Acute Coronary Syndrome (ACS); ST Elevation (STEMI) Myocardial Infarction; Ischemic Reperfusion Injury; Non-ST Elevation (NSTEMI) Myocardial Infarction; Angina, Unstable

Genomic evidence of reactive oxygen species elevation in papillary thyroid carcinoma with Hashimoto thyroiditis.

PubMed

Yi, Jin Wook; Park, Ji Yeon; Sung, Ji-Youn; Kwak, Sang Hyuk; Yu, Jihan; Chang, Ji Hyun; Kim, Jo-Heon; Ha, Sang Yun; Paik, Eun Kyung; Lee, Woo Seung; Kim, Su-Jin; Lee, Kyu Eun; Kim, Ju Han

2015-01-01

Elevated levels of reactive oxygen species (ROS) have been proposed as a risk factor for the development of papillary thyroid carcinoma (PTC) in patients with Hashimoto thyroiditis (HT). However, it has yet to be proven that the total levels of ROS are sufficiently increased to contribute to carcinogenesis. We hypothesized that if the ROS levels were increased in HT, ROS-related genes would also be differently expressed in PTC with HT. To find differentially expressed genes (DEGs) we analyzed data from the Cancer Genomic Atlas, gene expression data from RNA sequencing: 33 from normal thyroid tissue, 232 from PTC without HT, and 60 from PTC with HT. We prepared 402 ROS-related genes from three gene sets by genomic database searching. We also analyzed a public microarray data to validate our results. Thirty-three ROS related genes were up-regulated in PTC with HT, whereas there were only nine genes in PTC without HT (Chi-square p-value < 0.001). Mean log2 fold changes of up-regulated genes was 0.562 in HT group and 0.252 in PTC without HT group (t-test p-value = 0.001). In microarray data analysis, 12 of 32 ROS-related genes showed the same differential expression pattern with statistical significance. In gene ontology analysis, up-regulated ROS-related genes were related with ROS metabolism and apoptosis. Immune function-related and carcinogenesis-related gene sets were enriched only in HT group in Gene Set Enrichment Analysis. Our results suggested that ROS levels may be increased in PTC with HT. Increased levels of ROS may contribute to PTC development in patients with HT.

Analysis of reactive oxygen metabolites (ROMs) after cardiovascular surgery as a marker of oxidative stress.

PubMed

Kanaoka, Yuji; Inagaki, Ei-ichirou; Hamanaka, Souhei; Masaki, Hisao; Tanemoto, Kazuo

2010-10-01

The transient systemic low perfusion that occurs during cardiovascular surgery leads to oxidative stress and the production of free radicals. A systemic increase of various markers of oxidative stress has been shown to occur during cardiopulmonary bypass (CPB). However, these markers have not been adequately evaluated because they seem to be reactive and short-lived. Here, oxidative stress was measured using the free radical analytical system (FRAS 4) assessing the derivatives of reactive oxygen metabolites (d-ROMs) and biological antioxidant potential (BAP). Blood samples were taken from 21 patients undergoing elective cardiovascular surgery. CPB was used in 15 patients, and abdominal aortic aneurysm (AAA) surgery without CPB was performed in 6. Measurements of d-ROMs and BAP were taken before surgery, 1 day, 1 week, and 2 weeks after surgery, and oxidative stress was evaluated. The d-ROM level increased gradually after cardiovascular surgery up to 2 weeks. Over time, the d-ROM level after surgery involving CPB became higher than that after AAA surgery. This difference reached statistical significance at 1 week and lasted to 2 weeks. The prolongation of CPB was prone to elevate the d-ROM level whereas the duration of the aortic clamp in AAA surgery had no relation to the d-ROM level. The BAP was also elevated after surgery, and was positively correlated with the level of d-ROMs. In this study, patients who underwent cardiovascular surgery involving CPB had significant oxidative damage. The production of ROMs was shown to depend on the duration of CPB. Damage can be reduced if CPB is avoided. When CPB must be used, shortening the CPB time may be effective in reducing oxidative stress.

Dietary nitrate increases arginine availability and protects mitochondrial complex I and energetics in the hypoxic rat heart

PubMed Central

Ashmore, Tom; Fernandez, Bernadette O; Branco-Price, Cristina; West, James A; Cowburn, Andrew S; Heather, Lisa C; Griffin, Julian L; Johnson, Randall S; Feelisch, Martin; Murray, Andrew J

2014-01-01

Hypoxic exposure is associated with impaired cardiac energetics in humans and altered mitochondrial function, with suppressed complex I-supported respiration, in rat heart. This response might limit reactive oxygen species generation, but at the cost of impaired electron transport chain (ETC) activity. Dietary nitrate supplementation improves mitochondrial efficiency and can promote tissue oxygenation by enhancing blood flow. We therefore hypothesised that ETC dysfunction, impaired energetics and oxidative damage in the hearts of rats exposed to chronic hypoxia could be alleviated by sustained administration of a moderate dose of dietary nitrate. Male Wistar rats (n = 40) were given water supplemented with 0.7 mmol l−1 NaCl (as control) or 0.7 mmol l−1 NaNO3, elevating plasma nitrate levels by 80%, and were exposed to 13% O2 (hypoxia) or normoxia (n = 10 per group) for 14 days. Respiration rates, ETC protein levels, mitochondrial density, ATP content and protein carbonylation were measured in cardiac muscle. Complex I respiration rates and protein levels were 33% lower in hypoxic/NaCl rats compared with normoxic/NaCl controls. Protein carbonylation was 65% higher in hearts of hypoxic rats compared with controls, indicating increased oxidative stress, whilst ATP levels were 62% lower. Respiration rates, complex I protein and activity, protein carbonylation and ATP levels were all fully protected in the hearts of nitrate-supplemented hypoxic rats. Both in normoxia and hypoxia, dietary nitrate suppressed cardiac arginase expression and activity and markedly elevated cardiac l-arginine concentrations, unmasking a novel mechanism of action by which nitrate enhances tissue NO bioavailability. Dietary nitrate therefore alleviates metabolic abnormalities in the hypoxic heart, improving myocardial energetics. PMID:25172947

The Effects of Oxygen Therapy on Myocardial Salvage in ST Elevation Myocardial Infarction Treated with Acute Percutaneous Coronary Intervention: The Supplemental Oxygen in Catheterized Coronary Emergency Reperfusion (SOCCER) Study.

PubMed

Khoshnood, Ardavan; Carlsson, Marcus; Akbarzadeh, Mahin; Bhiladvala, Pallonji; Roijer, Anders; Bodetoft, Stefan; Höglund, Peter; Zughaft, David; Todorova, Lizbet; Erlinge, David; Ekelund, Ulf

2015-01-01

Despite a lack of scientific evidence, oxygen has long been a part of standard treatment for patients with acute myocardial infarction (AMI). However, several studies suggest that oxygen therapy may have negative cardiovascular effects. We here describe a randomized controlled trial, i.e. Supplemental Oxygen in Catheterized Coronary Emergency Reperfusion (SOCCER), aiming to evaluate the effect of oxygen therapy on myocardial salvage and infarct size in patients with ST elevation myocardial infarction (STEMI) treated with a primary percutaneous coronary intervention (PCI). One hundred normoxic STEMI patients accepted for a primary PCI are randomized in the ambulance to either standard oxygen therapy or no supplemental oxygen. All patients undergo cardiovascular magnetic resonance imaging (CMR) 2-6 days after the primary PCI, and a subgroup of 50 patients undergo an extended echocardiography during admission and at 6 months. All patients are followed for 6 months for hospital admission for heart failure and subjective perception of health. The primary endpoint is the myocardial salvage index on CMR. Even though oxygen therapy is a part of standard care, oxygen may not be beneficial for patients with AMI and is possibly even harmful. The results of the present and concurrent oxygen trials may change international treatment guidelines for patients with AMI or ischemia.

Reactive oxygen species activate differentiation gene transcription of acute myeloid leukemia cells via the JNK/c-JUN signaling pathway.

PubMed

Lam, Chung Fan; Yeung, Hoi Ting; Lam, Yuk Man; Ng, Ray Kit

2018-05-01

Reactive oxygen species (ROS) and altered cellular redox status are associated with many malignancies. Acute myeloid leukemia (AML) cells are maintained at immature state by differentiation blockade, which involves deregulation of transcription factors in myeloid differentiation. AML cells can be induced to differentiate by phorbol-12-myristate-13-acetate (PMA), which possesses pro-oxidative activity. However, the signaling events mediated by ROS in the activation of transcriptional program during AML differentiation has not been fully elucidated. Here, we investigated AML cell differentiation by treatment with PMA and ROS scavenger N-acetyl-l-cysteine (NAC). We observed elevation of intracellular ROS level in the PMA-treated AML cells, which correlated with differentiated cell morphology and increased CD11b + mature cell population. The effect of PMA can be abolished by NAC co-treatment, supporting the involvement of ROS in the process. Moreover, we demonstrated that short ROS elevation mediated cell cycle arrest, but failed to activate myeloid gene transcription; whereas prolonged ROS elevation activated JNK/c-JUN signaling pathway. Inhibition of JNK suppressed the expression of key myeloid transcriptional regulators c-JUN, SPI-1 and MAFB, and prevented AML cells from undergoing terminal differentiation. These findings provide new insights into the crucial role of JNK/c-Jun signaling pathway in the activation of transcriptional program during ROS-mediated AML differentiation. Copyright © 2018 Elsevier Ltd. All rights reserved.

The Interactive Effects of Elevated CO2 and Ammonium Enrichment on the Physiological Performances of Saccharina japonica (Laminariales, Phaeophyta)

NASA Astrophysics Data System (ADS)

Kang, Jin Woo; Chung, Ik Kyo

2018-04-01

Environmental challenges such as ocean acidification and eutrophication influence the physiology of kelp species. We investigated their interactive effects on Saccharina japonica (Laminariales, Phaeophyta) under two pH conditions [Low, 7.50; High (control), 8.10] and three NH4 +concentrations (Low, 4; Medium, 60; High, 120 μM). The degree of variation of pH values in the culture medium and inhibition rate of photosynthetic oxygen evolution by acetazolamide were affected by pH treatments. Relative growth rates, carbon, nitrogen, and the C:N ratio in tissue samples were influenced by higher concentrations of NH4 + . Rates of photosynthetic oxygen evolution were enhanced under elevated CO2 or NH4 +conditions, independently, but these two factors did not show an interactive effect. However, rates of NH4 +uptake were influenced by the interactive effect of increased CO2 under elevated NH4 +treatment. Although ocean acidification and eutrophication states had an impact on physiological performance, chlorophyll fluorescence was not affected by those conditions. Our results indicated that the physiological reactions by this alga were influenced to some extent by a rise in the levels of CO2 and NH4 + . Therefore, we expect that the biomass accumulation of S. japonica may well increase under future scenarios of ocean acidification and eutrophication.

Mitochondrial reactive oxygen species enhance AMP-activated protein kinase activation in the endothelium of patients with coronary artery disease and diabetes.

PubMed

Mackenzie, Ruth M; Salt, Ian P; Miller, William H; Logan, Angela; Ibrahim, Hagar A; Degasperi, Andrea; Dymott, Jane A; Hamilton, Carlene A; Murphy, Michael P; Delles, Christian; Dominiczak, Anna F

2013-03-01

The aim of the present study was to determine whether the endothelial dysfunction associated with CAD (coronary artery disease) and T2D (Type 2 diabetes mellitus) is concomitant with elevated mtROS (mitochondrial reactive oxygen species) production in the endothelium and establish if this, in turn, regulates the activity of endothelial AMPK (AMP-activated protein kinase). We investigated endothelial function, mtROS production and AMPK activation in saphenous veins from patients with advanced CAD. Endothelium-dependent vasodilation was impaired in patients with CAD and T2D relative to those with CAD alone. Levels of mitochondrial H(2)O(2) and activity of AMPK were significantly elevated in primary HSVECs (human saphenous vein endothelial cells) from patients with CAD and T2D compared with those from patients with CAD alone. Incubation with the mitochondria-targeted antioxidant, MitoQ(10) significantly reduced AMPK activity in HSVECs from patients with CAD and T2D but not in cells from patients with CAD alone. Elevated mtROS production in the endothelium of patients with CAD and T2D increases AMPK activation, supporting a role for the kinase in defence against oxidative stress. Further investigation is required to determine whether pharmacological activators of AMPK will prove beneficial in the attenuation of endothelial dysfunction in patients with CAD and T2D.

Oxygen Isotope Compositions of Meteoric Water Across an Elevation Gradient in Southern Peru

NASA Astrophysics Data System (ADS)

Xu, D. R.; White, E.; Cassel, E. J.; Lynch, B.; Yanites, B.; Breecker, D.

2017-12-01

The Central Andes is a prime example of elevated topography generated by oceanic plate subduction. Whereas previous stable isotope studies have investigated the paleoelevation of the Andean Eastern Cordillera, little is known about the paleoelevation of the Western Cordillera, where arc volcanism now occurs. As a first step towards studying the paleoelevation of this region, we investigated the change in δ18O values of modern soil waters across an elevation gradient from sea level to about 4725 meters in southern Peru. We sampled soil profiles from 5 to 80 cm in 15-20cm increments, and we sampled water from flowing natural streams at various elevations. We used cryogenic vacuum extraction to quantitatively remove non-structural water from soil samples. The δ18O values of water extracted from soil samples varies with the depth in the soil due to the diminishing effect of seasonality and evaporation. Every high elevation (>3500m) soil profile we measured had nearly constant δ18O values below 5cm and a total range of δ18O values between -12.8‰ and -17.1‰, apart from the Cusco profile. In the Cusco profile, the δ18O values ranged from -7.2 ‰ at 5 cm to -21.8 ‰ at 60 cm, defining a strong monotonic decrease not seen in other soil profiles. The δ18O trend in the Cusco profile may be different due to the impact of evaporation, soil hydrology, and/or seasonality in the δ18O values of precipitation. Further spatial analysis must be conducted to pinpoint a specific cause. Considering only the samples collected below 40cm, which are likely the best estimate of mean annual precipitation, the δ18O values decrease with increasing elevation at a rate higher than the global mean, suggesting that oxygen isotope paleoaltimetry can work in this study region.

Crouch severity is a poor predictor of elevated oxygen consumption in cerebral palsy.

PubMed

Steele, Katherine M; Shuman, Benjamin R; Schwartz, Michael H

2017-07-26

Children with cerebral palsy (CP) expend more energy to walk compared to typically-developing peers. One of the most prevalent gait patterns among children with CP, crouch gait, is often singled out as especially exhausting. The dynamics of crouch gait increase external flexion moments and the demand on extensor muscles. This elevated demand is thought to dramatically increase energy expenditure. However, the impact of crouch severity on energy expenditure has not been investigated among children with CP. We evaluated oxygen consumption and gait kinematics for 573 children with bilateral CP. The average net nondimensional oxygen consumption during gait of the children with CP (0.18±0.06) was 2.9 times that of speed-matched typically-developing peers. Crouch severity was only modestly related to oxygen consumption, with measures of knee flexion angle during gait explaining only 5-20% of the variability in oxygen consumption. While knee moment and muscle activity were moderately to strongly correlated with crouch severity (r 2 =0.13-0.73), these variables were only weakly correlated with oxygen consumption (r 2 =0.02-0.04). Thus, although the dynamics of crouch gait increased muscle demand, these effects did not directly result in elevated energy expenditure. In clinical gait analysis, assumptions about an individual's energy expenditure should not be based upon kinematics or kinetics alone. Identifying patient-specific factors that contribute to increased energy expenditure may provide new pathways to improve gait for children with CP. Copyright © 2017 Elsevier Ltd. All rights reserved.

Impact of reactive oxygen species on antioxidant capacity of male reproductive system.

PubMed

Riaz, Muhammad; Mahmood, Zahed; Shahid, Muhammad; Saeed, M Usman Qamar; Tahir, Imtiaz Mahmood; Shah, Sm Ali; Munir, Naveed; El-Ghorab, Ahmed

2016-09-01

The present research work was aimed to study the mutual interaction of reactive oxygen species (ROS) and basal cells antioxidant capacity in the male reproductive system and to further establish the association between selected heavy metals and stress markers. Total oxidant status (TOS) and total antioxidant status (TAS) of serum and seminal plasma were determined by automated photometric methods. The concentrations of Selenium (Se), Lead (Pb), and Cadmium (Cd) were determined by using atomic absorption spectrophotometer. The TOS was increased significantly (P <0.05) in seminal plasma as well as in the serum of the infertile group when compared with the fertile group. On the other hand, the TAS of the infertile group was found to be noticeably decreased (P <0.05) when compared with the TAS of the fertile group. Among the heavy metals, a noticeably lower concentration of Se was detected in the infertile group whereas markedly elevated levels of Cd and Pb were observed in the infertile group compared with the fertile group. Among the infertile group a significant inverse correlation (r = -0.521, P <0.05) was observed between Se and TOS and between Cd and Pb (r = -0.407, P <0.05). Contrarily among the infertile group a considerable positive relationship was established between Se and TAS (r = 0.507, P <0.05). It was concluded that the oxidant stress reduces the antioxidant activity in infertile men by elevating the production of ROS. A lower concentration of Se and elevated levels of Pb and Cd explain the individual's exposure to these heavy metals. The study also revealed that the heavy metal toxicity contributes significantly to male infertility. © The Author(s) 2015.

Maximum Oxygen Uptake During and After Long-Duration Space Flight

NASA Technical Reports Server (NTRS)

Moore, Alan D., Jr.; Evetts, Simon N.; Feiveson, Alan H.; Lee, Stuart M. C.; McCleary. Frank A.; Platts, Steven H.

2010-01-01

Decreased maximum oxygen consumption (VO2max) during and after space flight may impair a crewmember s ability to perform mission-critical work that is high intensity and/or long duration in nature (Human Research Program Integrated Research Plan Risk 2.1.2: Risk of Reduced Physical Performance Capabilities Due to Reduced Aerobic Capacity). When VO2max was measured in Space Shuttle experiments, investigators reported that it did not change during short-duration space flight but decreased immediately after flight. Similar conclusions, based on the heart rate (HR) response of Skylab crewmembers, were made previously concerning long-duration space flight. Specifically, no change in the in-flight exercise HR response in 8 of 9 Skylab crewmembers indicated that VO2max was maintained during flight, but the elevated exercise HR after flight indicated that VO2max was decreased after landing. More recently, a different pattern of in-flight exercise HR response, and assumed changes in VO2max, emerged from routine testing of International Space Station (ISS) crewmembers. Most ISS crewmembers experience an elevated in-flight exercise HR response early in their mission, with a gradual return toward preflight levels as the mission progresses. Similar to previous reports, exercise HR is elevated after ISS missions and returns to preflight levels by 30 days after landing. VO2max has not been measured either during or after long-duration space flight. The purposes of the ISS VO2max experiment are (1) to measure VO2max during and after long-duration spaceflight, and (2) to determine if submaximal exercise test results can be used to accurately estimate VO 2max.

Oxygenation state and twilight vision at 2438 m.

PubMed

Connolly, Desmond M

2011-01-01

Under twilight viewing conditions, hypoxia, equivalent to breathing air at 3048 m (10,000 ft), compromises low contrast acuity, dynamic contrast sensitivity, and chromatic sensitivity. Selected past experiments have been repeated under milder hypoxia, equivalent to altitude exposure below 2438 m (8000 ft), to further define the influence of oxygenation state on mesopic vision. To assess photopic and mesopic visual function, 12 subjects each undertook three experiments using the Contrast Acuity Assessment test, the Frequency Doubling Perimeter, and the Color Assessment and Diagnosis (CAD) test. Experiments were conducted near sea level breathing 15.2% oxygen (balance nitrogen) and 100% oxygen, representing mild hypobaric hypoxia at 2438 m (8000 ft) and the benefit of supplementary oxygen, respectively. Oxygenation state was a statistically significant determinant of visual performance on all three visual parameters at mesopic, but not photopic, luminance. Mesopic sensitivity was greater with supplementary oxygen, but the magnitude of each hypoxic decrement was slight. Hypoxia elevated mesopic contrast acuity thresholds by approximately 4%; decreased mesopic dynamic contrast sensitivity by approximately 2 dB; and extended mean color ellipse axis length by approximately one CAD unit at mesopic luminance (that is, hypoxia decreased chromatic sensitivity). The results indicate that twilight vision may be susceptible to conditions of altered oxygenation at upper-to-mid mesopic luminance with relevance to contemporary night flying, including using night vision devices. Supplementary oxygen should be considered when optimal visual performance is mission-critical during flight above 2438 m (8000 ft) in dim light.

Remedial Investigation Concept Plan for Picatinny Arsenal. Volume 2. Descriptions of and Sampling Plans for Remedial Investigation Sites

DTIC Science & Technology

1991-03-22

by sulfur dioxide to convert hexavalent chromium into trivalent chromium , and by sodium hydroxide to promote precipitation. After being transferred...Regulations COD chemical oxygen demand Cr chromium CTF chlorine trifluoride Cu copper 2,4-D 2,4-dichlorophenoxyaoetic acid 11DCE 1,1...the Site. Inorganic results for surface soil showed elevated values for arsenic, cadmium, chromium , lead, and zinc (Table 2.1). These levels are to be

Solid state oxygen sensor

DOEpatents

Garzon, Fernando H.; Brosha, Eric L.

1997-01-01

A potentiometric oxygen sensor is formed having a logarithmic response to a differential oxygen concentration while operating as a Nernstian-type sensor. Very thin films of mixed conducting oxide materials form electrode services while permitting diffusional oxygen access to the interface between the zirconia electrolyte and the electrode. Diffusion of oxygen through the mixed oxide is not rate-limiting. Metal electrodes are not used so that morphological changes in the electrode structure do not occur during extended operation at elevated temperatures.

Solid state oxygen sensor

DOEpatents

Garzon, F.H.; Brosha, E.L.

1997-12-09

A potentiometric oxygen sensor is formed having a logarithmic response to a differential oxygen concentration while operating as a Nernstian-type sensor. Very thin films of mixed conducting oxide materials form electrode services while permitting diffusional oxygen access to the interface between the zirconia electrolyte and the electrode. Diffusion of oxygen through the mixed oxide is not rate-limiting. Metal electrodes are not used so that morphological changes in the electrode structure do not occur during extended operation at elevated temperatures. 6 figs.

RNS60, a charge-stabilized nanostructure saline alters Xenopus Laevis oocyte biophysical membrane properties by enhancing mitochondrial ATP production

PubMed Central

Choi, Soonwook; Yu, Eunah; Kim, Duk-Soo; Sugimori, Mutsuyuki; Llinás, Rodolfo R

2015-01-01

We have examined the effects of RNS60, a 0.9% saline containing charge-stabilized oxygen nanobubble-based structures. RNS60 is generated by subjecting normal saline to Taylor–Couette–Poiseuille (TCP) flow under elevated oxygen pressure. This study, implemented in Xenopus laevis oocytes, addresses both the electrophysiological membrane properties and parallel biological processes in the cytoplasm. Intracellular recordings from defolliculated X. laevis oocytes were implemented in: (1) air oxygenated standard Ringer's solution, (2) RNS60-based Ringer's solution, (3) RNS10.3 (TCP-modified saline without excess oxygen)-based Ringer's, and (4) ONS60 (saline containing high pressure oxygen without TCP modification)-based Ringer's. RNS60-based Ringer's solution induced membrane hyperpolarization from the resting membrane potential. This effect was prevented by: (1) ouabain (a blocker of the sodium/potassium ATPase), (2) rotenone (a mitochondrial electron transfer chain inhibitor preventing usable ATP synthesis), and (3) oligomycin A (an inhibitor of ATP synthase) indicating that RNS60 effects intracellular ATP levels. Increased intracellular ATP levels following RNS60 treatment were directly demonstrated using luciferin/luciferase photon emission. These results indicate that RNS60 alters intrinsic the electrophysiological properties of the X. laevis oocyte membrane by increasing mitochondrial-based ATP synthesis. Ultrastructural analysis of the oocyte cytoplasm demonstrated increased mitochondrial length in the presence of RNS60-based Ringer's solution. It is concluded that the biological properties of RNS60 relate to its ability to optimize ATP synthesis. PMID:25742953

Reactive oxygen species: role in the development of cancer and various chronic conditions

PubMed Central

Waris, Gulam; Ahsan, Haseeb

2006-01-01

Oxygen derived species such as superoxide radical, hydrogen peroxide, singlet oxygen and hydroxyl radical are well known to be cytotoxic and have been implicated in the etiology of a wide array of human diseases, including cancer. Various carcinogens may also partly exert their effect by generating reactive oxygen species (ROS) during their metabolism. Oxidative damage to cellular DNA can lead to mutations and may, therefore, play an important role in the initiation and progression of multistage carcinogenesis. The changes in DNA such as base modification, rearrangement of DNA sequence, miscoding of DNA lesion, gene duplication and the activation of oncogenes may be involved in the initiation of various cancers. Elevated levels of ROS and down regulation of ROS scavengers and antioxidant enzymes are associated with various human diseases including various cancers. ROS are also implicated in diabtes and neurodegenerative diseases. ROS influences central cellular processes such as proliferation a, apoptosis, senescence which are implicated in the development of cancer. Understanding the role of ROS as key mediators in signaling cascades may provide various opportunities for pharmacological intervention. PMID:16689993

Elevated expression of glutathione peroxidase in PC12 cells results in protection against methamphetamine but not MPTP toxicity.

PubMed

Hom, D G; Jiang, D; Hong, E J; Mo, J Q; Andersen, J K

1997-06-01

In vivo administration of either 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) or methamphetamine (MA) produces damage to the dopaminergic nervous system which may be due in part to the generation of reactive oxygen species (ROS). The resistance of superoxide dismutase (SOD) over-expressing transgenic mice to the effects of both MPTP and MA suggests the involvement of superoxide in the resulting neurotoxicity of both compounds. Superoxide can be converted by SOD to hydrogen peroxide, which itself can cause cellular degeneration by reacting with free iron to produce highly reactive hydroxyl radicals resulting in damage to proteins, nucleic acids and membrane phospholipids. Hydrogen peroxide has also been reported to be produced via inhibition of NADH dehydrogenase by MPP + formed during oxidation of MPTP by MAO-B and by dopamine auto-oxidation following MA-induced dopamine release from synaptic vesicles within nerve terminals. To test whether hydrogen peroxide is an important factor in the toxicity of either of these two neurotoxins, we created clonal PC12 lines expressing elevated levels of the hydrogen peroxide-reducing enzyme glutathione peroxidase (GSHPx). Elevation of GSHPx levels in PC12 was found to diminish the rise in ROS levels and lipid peroxidation resulting from MA but not MPTP treatment. Elevated levels of GSHPx also appeared to prevent decreases in transport-mediated dopamine uptake produced via MA administration as well as to attenuate toxin-induced cell loss as measured by either MTT reduction or LDH release. Our data, therefore, suggest that hydrogen peroxide production likely contributes to MA toxicity in dopaminergic neurons.

Impact of CO2 on Intracranial Hypertension in Spaceflight. Visual Impairment and Intracranial Hypertension: An Emerging Spaceflight Risk [Part 1 and 2

NASA Technical Reports Server (NTRS)

Fogarty, Jennifer A.; Polk, James D.; Tarver, William J.; Gibson, Charles R.; Sargsyan, Ashot E.; Taddeo, Terrance A.; Alexander, David J.; Otto, Christian A.

2010-01-01

A. CO2 - Acute: Given the history of uneven removal of CO2 from spacecraft areas, there is a history of acute illness that impacts short-term health and performance. 1) Acute CO2 symptoms occur in space flight due to a combination of CO2 scrubbing limitations, microgravity-related lack of convection, and possibly interaction with microgravity-related physiological changes. 2) Reported symptoms mainly include headaches, malaise, and lethargy. Symptoms are treatable with analgesics, rest, temporarily increasing scrubbing capability, and breathing oxygen. This does not treat the underlying pathology. 3)ld prevent occurrence of symptoms. B. CO2 - Chronic: Given prolonged exposure to elevated CO2 levels, there is a history that the long-term health of the crew is impacted. 1) Chronic CO2 exposures occur in space flight due to a combination of CO2 scrubbing limitations and microgravity-related lack of convection, with possible contribution from microgravity-related physiological changes. 2) Since acute symptoms are experienced at levels significantly lower than expected, there are unidentified long-term effects from prolonged exposure to elevated CO2 levels on orbit. There have been long term effects seen terrestrially and research needed to further elucidate long term effects on orbit. 3) Recommended disposition: Research required to further elucidate long term effects. In particular, elucidation of the role of elevated CO2 on various levels of CO2 vasodilatation of intracranial blood vessels and its potential contribution to elevation of intracranial pressure.

Dissolved oxygen: Chapter 6

USGS Publications Warehouse

Senn, David; Downing-Kunz, Maureen; Novick, Emily

2016-01-01

Dissolved oxygen (DO) concentration serves as an important indicator of estuarine habitat condition, because all aquatic macro-organisms require some minimum DO level to survive and prosper. The instantaneous DO concentration, measured at a specific location in the water column, results from a balance between multiple processes that add or remove oxygen (Figure 6.1): primary production produces O2; aerobic respiration in the water column and sediments consumes O2; abiotic or microbially-mediated biogeochemical reactions utilize O2 as an oxidant (e.g., oxidation of ammonium, sulfide, and ferrous iron); O2 exchange occurs across the air:water interface in response to under- or oversaturated DO concentrations in the water column; and water currents and turbulent mixing transport DO into and out of zones in the water column. If the oxygen loss rate exceeds the oxygen production or input rate, DO concentration decreases. When DO losses exceed production or input over a prolonged enough period of time, hypoxia ((<2-3 mg/L) or anoxia can develop. Persistent hypoxia or anoxia causes stress or death in aquatic organism populations, or for organisms that can escape a hypoxic or anoxic area, the loss of habitat. In addition, sulfide, which is toxic to aquatic organisms and causes odor problems, escapes from sediments under low oxygen conditions. Low dissolved oxygen is a common aquatic ecosystem response to elevated organic

p21{sup WAF1/Cip1/Sdi1} knockout mice respond to doxorubicin with reduced cardiotoxicity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Terrand, Jerome; Xu, Beibei; Morrissy, Steve

2011-11-15

Doxorubicin (Dox) is an antineoplastic agent that can cause cardiomyopathy in humans and experimental animals. As an inducer of reactive oxygen species and a DNA damaging agent, Dox causes elevated expression of p21{sup WAF1/Cip1/Sdi1} (p21) gene. Elevated levels of p21 mRNA and p21 protein have been detected in the myocardium of mice following Dox treatment. With chronic treatment of Dox, wild type (WT) animals develop cardiomyopathy evidenced by elongated nuclei, mitochondrial swelling, myofilamental disarray, reduced cardiac output, reduced ejection fraction, reduced left ventricular contractility, and elevated expression of ANF gene. In contrast, p21 knockout (p21KO) mice did not show significantmore » changes in the same parameters in response to Dox treatment. In an effort to understand the mechanism of the resistance against Dox induced cardiomyopathy, we measured levels of antioxidant enzymes and found that p21KO mice did not contain elevated basal or inducible levels of glutathione peroxidase and catalase. Measurements of 6 circulating cytokines indicated elevation of IL-6, IL-12, IFN{gamma} and TNF{alpha} in Dox treated WT mice but not p21KO mice. Dox induced elevation of IL-6 mRNA was detected in the myocardium of WT mice but not p21KO mice. While the mechanism of the resistance against Dox induced cardiomyopathy remains unclear, lack of inflammatory response may contribute to the observed cardiac protection in p21KO mice. -- Highlights: Black-Right-Pointing-Pointer Doxorubicin induces p21 elevation in the myocardium. Black-Right-Pointing-Pointer Doxorubicin causes dilated cardiomyopathy in wild type mice. Black-Right-Pointing-Pointer p21 Knockout mice are resistant against doxorubicin induced cardiomyopathy. Black-Right-Pointing-Pointer Lack of inflammatory response correlates with the resistance in p21 knockout mice.« less

Dexamethasone therapy for preventing delayed encephalopathy after carbon monoxide poisoning.

PubMed

Li, Q; Song, J J; Zhang, H Y; Fu, K; Lan, H B; Deng, Y

2015-01-01

We investigated dexamethasone therapy for preventing delayed encephalopathy after carbon monoxide (CO) poisoning. Eighty healthy male rats were exposed to CO and randomly divided into four groups: hyperbaric oxygen treatment (H), treatment (D), combined hyperbaric and dexamethasone treatment (C), and a control (M) group in which the rats inhaled CO to coma in the hyperbaric oxygen chamber, then were removed without further treatment. Twelve rats were put into the hyperbaric oxygen chamber and treated with air for 60 min (N) group. An eight arm maze was used to evaluate cognitive and memory abilities of these mice. Serum myelin basic protein (MBP) levels were evaluated using ELISA, and magnetic resonance imaging was used to observe brain demyelination and morbidity associated with delayed encephalopathy. A sample of the hippocampus from each group was examined by light microscopy. Cognitive and memory functions decreased in the control group M. Three days after CO poisoning, the serum MBP level of each group increased significantly. On Day 10 after CO poisoning, the MBP levels in groups C and D decreased significantly, but returned to normal on Day 18. MBP levels in the M and H groups were elevated at all time points. Brain MRIs showed significant differences among C, D, H and control M groups. Hematoxylin & eosin staining of the hippocampus showed greater damage in the control M and H groups. Early dexamethasone treatment may be useful for preventing delayed encephalopathy after CO poisoning and may reduce serum MBP levels.

Characterization of the Differential Response of Endothelial Cells Exposed to Normal and Elevated Laminar Shear Stress

PubMed Central

White, Stephen J; Hayes, Elaine M; Lehoux, Stéphanie; Jeremy, Jamie Y; Horrevoets, Anton JG; Newby, Andrew C

2011-01-01

Most acute coronary events occur in the upstream region of stenotic atherosclerotic plaques that experience laminar shear stress (LSS) elevated above normal physiological levels. Many studies have described the atheroprotective effect on endothelial behavior of normal physiological LSS (approximately 15 dynes/cm2) compared to static or oscillatory shear stress (OSS), but it is unknown whether the levels of elevated shear stress imposed by a stenotic plaque would preserve, enhance or reverse this effect. Therefore we used transcriptomics and related functional analyses to compare human endothelial cells exposed to laminar shear stress of 15 (LSS15-normal) or 75 dynes/cm2 (LSS75-elevated). LSS75 upregulated expression of 145 and downregulated expression of 158 genes more than twofold relative to LSS15. Modulation of the metallothioneins (MT1-G, -M, -X) and NADPH oxidase subunits (NOX2, NOX4, NOX5, and p67phox) accompanied suppression of reactive oxygen species production at LSS75. Shear induced changes in dual specificity phosphatases (DUSPs 1, 5, 8, and 16 increasing and DUSPs 6 and 23 decreasing) were observed as well as reduced ERK1/2 but increased p38 MAP kinase phosphorylation. Amongst vasoactive substances, endothelin-1 expression decreased whereas vasoactive intestinal peptide (VIP) and prostacyclin expression increased, despite which intracellular cAMP levels were reduced. Promoter analysis by rVISTA identified a significant over representation of ATF and Nrf2 transcription factor binding sites in genes upregulated by LSS75 compared to LSS15. In summary, LSS75 induced a specific change in behavior, modifying gene expression, reducing ROS levels, altering MAP kinase signaling and reducing cAMP levels, opening multiple avenues for future study. J. Cell. Physiol. 226: 2841–2848, 2011. © 2011 Wiley-Liss, Inc. PMID:21302282

Characterization of the differential response of endothelial cells exposed to normal and elevated laminar shear stress.

PubMed

White, Stephen J; Hayes, Elaine M; Lehoux, Stéphanie; Jeremy, Jamie Y; Horrevoets, Anton J G; Newby, Andrew C

2011-11-01

Most acute coronary events occur in the upstream region of stenotic atherosclerotic plaques that experience laminar shear stress (LSS) elevated above normal physiological levels. Many studies have described the atheroprotective effect on endothelial behavior of normal physiological LSS (approximately 15 dynes/cm(2)) compared to static or oscillatory shear stress (OSS), but it is unknown whether the levels of elevated shear stress imposed by a stenotic plaque would preserve, enhance or reverse this effect. Therefore we used transcriptomics and related functional analyses to compare human endothelial cells exposed to laminar shear stress of 15 (LSS15-normal) or 75 dynes/cm(2) (LSS75-elevated). LSS75 upregulated expression of 145 and downregulated expression of 158 genes more than twofold relative to LSS15. Modulation of the metallothioneins (MT1-G, -M, -X) and NADPH oxidase subunits (NOX2, NOX4, NOX5, and p67phox) accompanied suppression of reactive oxygen species production at LSS75. Shear induced changes in dual specificity phosphatases (DUSPs 1, 5, 8, and 16 increasing and DUSPs 6 and 23 decreasing) were observed as well as reduced ERK1/2 but increased p38 MAP kinase phosphorylation. Amongst vasoactive substances, endothelin-1 expression decreased whereas vasoactive intestinal peptide (VIP) and prostacyclin expression increased, despite which intracellular cAMP levels were reduced. Promoter analysis by rVISTA identified a significant over representation of ATF and Nrf2 transcription factor binding sites in genes upregulated by LSS75 compared to LSS15. In summary, LSS75 induced a specific change in behavior, modifying gene expression, reducing ROS levels, altering MAP kinase signaling and reducing cAMP levels, opening multiple avenues for future study. Copyright © 2011 Wiley-Liss, Inc.

Extracorporeal membrane oxygenation and cytokine adsorption

PubMed Central

Träger, Karl

2018-01-01

Extracorporeal membrane oxygenation (ECMO) is an increasingly used technology for mechanical support of respiratory and cardio-circulatory failure. Excessive systemic inflammatory response is observed during sepsis and after cardiopulmonary bypass (CPB) with similar clinical features. The overwhelming inflammatory response is characterized by highly elevated pro- and anti-inflammatory cytokine levels. The excessive cytokine release during the overwhelming inflammatory response may result in multiple organ damage and failure. During ECMO therapy activation of complement and contact systems occur which may be followed by cytokine release. Controlling excessively increased cytokines may be considered as a valuable treatment option. Hemoadsorption therapy may be used to decrease cytokine levels in case of excessive inflammatory response and due to its unspecific adsorptive characteristics also substances like myoglobin, free hemoglobin or bilirubin. Controlling pro-inflammatory response with hemoadsorption may have positive impact on the endothelial glycocalix and also may be advantageous for maintenance of the vascular barrier function which plays a pivotal role in the development of tissue edema and oxygen mismatch. Hemoadsorption therapy seems to offer a promising new option for the treatment of patients with overwhelming inflammatory response leading to faster hemodynamic and metabolic stabilization finally resulting in preserved organ functions. PMID:29732183

Extracorporeal membrane oxygenation and cytokine adsorption.

PubMed

Datzmann, Thomas; Träger, Karl

2018-03-01

Extracorporeal membrane oxygenation (ECMO) is an increasingly used technology for mechanical support of respiratory and cardio-circulatory failure. Excessive systemic inflammatory response is observed during sepsis and after cardiopulmonary bypass (CPB) with similar clinical features. The overwhelming inflammatory response is characterized by highly elevated pro- and anti-inflammatory cytokine levels. The excessive cytokine release during the overwhelming inflammatory response may result in multiple organ damage and failure. During ECMO therapy activation of complement and contact systems occur which may be followed by cytokine release. Controlling excessively increased cytokines may be considered as a valuable treatment option. Hemoadsorption therapy may be used to decrease cytokine levels in case of excessive inflammatory response and due to its unspecific adsorptive characteristics also substances like myoglobin, free hemoglobin or bilirubin. Controlling pro-inflammatory response with hemoadsorption may have positive impact on the endothelial glycocalix and also may be advantageous for maintenance of the vascular barrier function which plays a pivotal role in the development of tissue edema and oxygen mismatch. Hemoadsorption therapy seems to offer a promising new option for the treatment of patients with overwhelming inflammatory response leading to faster hemodynamic and metabolic stabilization finally resulting in preserved organ functions.

Cadmium-dependent oxygen limitation affects temperature tolerance in eastern oysters (Crassostrea virginica Gmelin).

PubMed

Lannig, Gisela; Cherkasov, Anton S; Pörtner, Hans-O; Bock, Christian; Sokolova, Inna M

2008-04-01

Marine ectotherms, including oysters are exposed to variable environmental conditions in coastal shallow waters and estuaries. In the light of global climate change, additional stressors like pollution might pose higher risk to populations. On the basis of the concept of oxygen- and capacity-limited thermal tolerance in aquatic ectotherms (40), we show that a persistent pollutant, cadmium, can have detrimental effects on oysters (Crassostrea virginica). During acute warming from 20 to 28 degrees C (4 degrees C/48 h) standard metabolic rate (SMR) rose in control and cadmium-exposed (50 microg Cd2+/l) animals, with a consistently higher SMR in Cd-exposed oysters. Additionally, Cd-exposed oysters showed a stronger temperature-dependent decrease in hemolymph oxygen partial pressures. This observation indicates that the effect of temperature on aerobic metabolism was exacerbated due to the additional Cd stress. The oxygen delivery systems could not provide enough oxygen to cover Cd-induced elevated metabolic demands at high temperatures. Interestingly, cardiac performance (measured as the heart rate and hemolymph supply to tissues) rose to a similar extent in control and Cd-exposed oysters with warming indicating that cardiac output was unable to compensate for elevated energy demand in Cd-exposed oysters. Together with the literature data on metal-induced reduction of ventilatory capacity, these findings suggest that synergistic effects of elevated temperatures and cadmium exposure led to oxygen limitation by impaired performance in oxygen supply through ventilation and circulation. Overall, cadmium exposure resulted in progressive hypoxemia in oysters at high temperatures, suggesting that the thermal tolerance window is narrowed in marine ectotherms inhabiting polluted areas compared with pristine environments.

Dietary deficiency of vitamin E aggravates retinal ganglion cell death in experimental glaucoma of rats.

PubMed

Ko, Mei-Lan; Peng, Pai-Huei; Hsu, Shens-Yao; Chen, Chau-Fong

2010-09-01

Investigate the effect of dietary vitamin E (Vit E) on the retinas of a rat model of induced glaucoma, in which surgically induced elevation of intraocular pressure (IOP) is associated with an increase in reactive oxygen species. Rats were fed a standard chow, Vit E-supplemented diet, or Vit E-deficient diet and subjected to surgically induced IOP elevation (or sham surgery) for five weeks. The retinal ganglion cells (RGCs) were subjected to retrograde fluorescent tracer labeling. The mean number of RGCs of rats on the standard chow, Vit E-supplemented diet, and Vit E-deficient diet were 79.6%, 78.6%, and 71.3% of controls, respectively. Lipid peroxidation of the retinas of rats given a Vit E-deficient diet were significantly higher after IOP elevation for three days (14.42 +/- 0.25 microM, P = 0.016) and five weeks (10.46 +/- 0.11 microM, p = 0.042), compared to rats given standard chow (11.37 +/- 0.31 microM; 8.95 +/- 0.16 microM). Compared with rats given standard chow, rats given a Vit E-deficient diet had significantly elevated concentrations of glutathione (p = 0.032), but no significant differences in the levels of total superoxide dismutase (SOD), Cu/Zn SOD, or catalase activities three days after IOP elevation. Rats fed a Vit E-deficient diet with surgically induced IOP elevation experience significantly more RGC death than rats fed a normal diet. This phenomenon may be related to the increased level of lipid peroxidation in Vit E-deficient rats.

Oxygen index tests of thermosetting resins

NASA Technical Reports Server (NTRS)

Gilwee, W. J., Jr.; Parker, J. A.; Kourtides, D. A.

1980-01-01

The flammability characteristics of nine thermosetting resins under evaluation for use in aircraft interiors are described. These resins were evaluated using the Oxygen Index (ASTM 2863) testing procedure. The test specimens consisted of both neat resin and glass reinforced resin. When testing glass-reinforced samples it was observed that Oxygen Index values varied inversely with resin content. Oxygen values were also obtained on specimens exposed to temperatures up to 300 C. All specimens experienced a decline in Oxygen Index when tested at an elevated temperature.

Mechanical circulatory support is associated with loss of platelet receptors glycoprotein Ibα and glycoprotein VI.

PubMed

Lukito, P; Wong, A; Jing, J; Arthur, J F; Marasco, S F; Murphy, D A; Bergin, P J; Shaw, J A; Collecutt, M; Andrews, R K; Gardiner, E E; Davis, A K

2016-11-01

Essentials Relationship of acquired von Willebrand disease (VWD) and platelet dysfunction is explored. Patients with ventricular assist devices and on extracorporeal membrane oxygenation are investigated. Acquired VWD and platelet receptor shedding is demonstrated in the majority of patients. Loss of platelet adhesion receptors glycoprotein (GP) Ibα and GPVI may increase bleeding risk. Background Ventricular assist devices (VADs) and extracorporeal membrane oxygenation (ECMO) are associated with bleeding that is not fully explained by anticoagulant or antiplatelet use. Exposure of platelets to elevated shear in vitro leads to increased shedding. Objectives To investigate whether loss of platelet receptors occurs in vivo, and the relationship with acquired von Willebrand syndrome (AVWS). Methods Platelet counts, coagulation tests and von Willebrand factor (VWF) analyses were performed on samples from 21 continuous flow VAD (CF-VAD), 20 ECMO, 12 heart failure and seven aortic stenosis patients. Levels of platelet receptors were measured by flow cytometry or ELISA. Results The loss of high molecular weight VWF multimers was observed in 18 of 19 CF-VAD and 14 of 20 ECMO patients, consistent with AVWS. Platelet receptor shedding was demonstrated by elevated soluble glycoprotein (GP) VI levels in plasma and significantly reduced surface GPIbα and GPVI levels in CF-VAD and ECMO patients as compared with healthy donors. Platelet receptor levels were also significantly reduced in heart failure patients. Conclusions These data link AVWS and increased platelet receptor shedding in patients with CF-VADs or ECMO for the first time. Loss of the platelet surface receptors GPIbα and GPVI in heart failure, CF-VAD and ECMO patients may contribute to ablated platelet adhesion/activation, and limit thrombus formation under high/pathologic shear conditions. © 2016 International Society on Thrombosis and Haemostasis.

CNTF-ACM promotes mitochondrial respiration and oxidative stress in cortical neurons through upregulating L-type calcium channel activity.

PubMed

Sun, Meiqun; Liu, Hongli; Xu, Huanbai; Wang, Hongtao; Wang, Xiaojing

2016-09-01

A specialized culture medium termed ciliary neurotrophic factor-treated astrocyte-conditioned medium (CNTF-ACM) allows investigators to assess the peripheral effects of CNTF-induced activated astrocytes upon cultured neurons. CNTF-ACM has been shown to upregulate neuronal L-type calcium channel current activity, which has been previously linked to changes in mitochondrial respiration and oxidative stress. Therefore, the aim of this study was to evaluate CNTF-ACM's effects upon mitochondrial respiration and oxidative stress in rat cortical neurons. Cortical neurons, CNTF-ACM, and untreated control astrocyte-conditioned medium (UC-ACM) were prepared from neonatal Sprague-Dawley rat cortical tissue. Neurons were cultured in either CNTF-ACM or UC-ACM for a 48-h period. Changes in the following parameters before and after treatment with the L-type calcium channel blocker isradipine were assessed: (i) intracellular calcium levels, (ii) mitochondrial membrane potential (ΔΨm), (iii) oxygen consumption rate (OCR) and adenosine triphosphate (ATP) formation, (iv) intracellular nitric oxide (NO) levels, (v) mitochondrial reactive oxygen species (ROS) production, and (vi) susceptibility to the mitochondrial complex I toxin rotenone. CNTF-ACM neurons displayed the following significant changes relative to UC-ACM neurons: (i) increased intracellular calcium levels (p < 0.05), (ii) elevation in ΔΨm (p < 0.05), (iii) increased OCR and ATP formation (p < 0.05), (iv) increased intracellular NO levels (p < 0.05), (v) increased mitochondrial ROS production (p < 0.05), and (vi) increased susceptibility to rotenone (p < 0.05). Treatment with isradipine was able to partially rescue these negative effects of CNTF-ACM (p < 0.05). CNTF-ACM promotes mitochondrial respiration and oxidative stress in cortical neurons through elevating L-type calcium channel activity.

Gene sequence variations and expression patterns of mitochondrial genes are associated with the adaptive evolution of two Gynaephora species (Lepidoptera: Lymantriinae) living in different high-elevation environments.

PubMed

Zhang, Qi-Lin; Zhang, Li; Zhao, Tian-Xuan; Wang, Juan; Zhu, Qian-Hua; Chen, Jun-Yuan; Yuan, Ming-Long

2017-04-30

The adaptive evolution of animals to high-elevation environments has been extensively studied in vertebrates, while few studies have focused on insects. Gynaephora species (Lepidoptera: Lymantriinae) are endemic to the Qinghai-Tibetan Plateau (QTP) and represent an important insect pest of alpine meadows. Here, we present a detailed comparative analysis of the mitochondrial genomes (mitogenomes) of two Gynaephora species inhabiting different high-elevation environments: G. alpherakii and G. menyuanensis. The results indicated that the general mitogenomic features (genome size, nucleotide composition, codon usage and secondary structures of tRNAs) were well conserved between the two species. All of mitochondrial protein-coding genes were evolving under purifying selection, suggesting that selection constraints may play a role in ensuring adequate energy production. However, a number of substitutions and indels were identified that altered the protein conformations of ATP8 and NAD1, which may be the result of adaptive evolution of the two Gynaephora species to different high-elevation environments. Levels of gene expression for nine mitochondrial genes in nine different developmental stages were significantly suppressed in G. alpherakii, which lives at the higher elevation (~4800m above sea level), suggesting that gene expression patterns could be modulated by atmospheric oxygen content and environmental temperature. These results enhance our understanding of the genetic bases for the adaptive evolution of insects endemic to the QTP. Copyright © 2017 Elsevier B.V. All rights reserved.

Experimental manipulations of tissue oxygen supply do not affect warming tolerance of European perch.

PubMed

Brijs, Jeroen; Jutfelt, Fredrik; Clark, Timothy D; Gräns, Albin; Ekström, Andreas; Sandblom, Erik

2015-08-01

A progressive inability of the cardiorespiratory system to maintain systemic oxygen supply at elevated temperatures has been suggested to reduce aerobic scope and the upper thermal limit of aquatic ectotherms. However, few studies have directly investigated the dependence of thermal limits on oxygen transport capacity. By manipulating oxygen availability (via environmental hyperoxia) and blood oxygen carrying capacity (via experimentally induced anaemia) in European perch (Perca fluviatilis Linneaus), we investigated the effects of oxygen transport capacity on aerobic scope and the critical thermal maximum (CT(max)). Hyperoxia resulted in a twofold increase in aerobic scope at the control temperature of 23°C, but this did not translate to an elevated CT(max) in comparison with control fish (34.6±0.1 versus 34.0±0.5°C, respectively). Anaemia (∼43% reduction in haemoglobin concentration) did not cause a reduction in aerobic scope or CT(max) (33.8±0.3°C) compared with control fish. Additionally, oxygen consumption rates of anaemic perch during thermal ramping increased in a similar exponential manner to that in control fish, highlighting that perch have an impressive capacity to compensate for a substantial reduction in blood oxygen carrying capacity. Taken together, these results indicate that oxygen limitation is not a universal mechanism determining the CT(max) of fishes. © 2015. Published by The Company of Biologists Ltd.

Toxicity and oxidative stress induced by chromium in workers exposed from different occupational settings around the globe: A review.

PubMed

Junaid, Muhammad; Hashmi, Muhammad Zaffar; Malik, Riffat Naseem; Pei, De-Sheng

2016-10-01

The present review focused on the levels and toxicological status of heavy metals especially chromium (Cr) in the exposed workers from different occupational settings around the globe and in Pakistan. It was found that exposed workers from leather tanning and metal plating units showed elevated levels of Cr than the workers from other occupational settings. Cr and other heavy metals level in biological matrices of the exposed workers in different occupational settings revealed that developing countries are severely contaminated. Occupational settings from the Sialkot district, Pakistan exhibited elevated level of Cr in biological entities of the exposed workers. Review suggested that higher level of Cr exposure to the workers enhance the oxidative stress (reactive oxygen species (ROS) and hydroxyl (OH) radical generation) which may cause; cellular and molecular damage such as genotoxicity and chromosomal aberration formations, and carcinogenic effects. This review will help to understand the Cr contamination mechanisms and associated health implications in different occupational settings around the globe in general and particularly to Pakistan. This study will also assist occupational health and safety management authorities to devise or change the Cr recommended exposure limits (REL) for different occupational settings.

A newly developed solution enhances thirty-hour preservation in a canine lung transplantation model.

PubMed

Liu, C J; Ueda, M; Kosaka, S; Hirata, T; Yokomise, H; Inui, K; Hitomi, S; Wada, H

1996-09-01

Ischemia and reperfusion cause the production of oxygen free radicals. These damage grafts or disrupt normal vascular homeostatic mechanisms, with a parallel reduction in endothelial nitric oxide and adenosine 3',5'-cyclic monophosphate levels. We hypothesized that lung preservation failure may be related to these events. To improve lung preservation, we prepared a new ET-Kyoto solution, which contains N-acetylcysteine (a radical scavenger), nitroglycerin (to elevate the nitric oxide level), and dibutyryl adenosine 3',5'-cyclic monophosphate (to elevate the adenosine 3',5'-cyclic monophosphate level) and examined its efficacy in a canine single-lung transplantation model. Lungs were flushed with new ET-Kyoto solution (group I, n = 9), basal ET-Kyoto solution (group II, n = 6), basal ET-Kyoto solution plus ethanol and propylene glycol (solvents of nitroglycerin; group III, n = 6), or low-potassium dextran glucose solution (group IV, n = 6), and stored at 4 degrees C for 30 hours. After left single-lung transplantation, the right main bronchus and right pulmonary artery were ligated and the functions of the transplanted lung were assessed for 6 hours. Arterial oxygen tension was significantly higher in group I than in groups II, III, and IV (p < 0.05). Peak inspiratory pressure and wet-to-dry lung weight ratio were significantly lower in group I than in groups II and IV (p < 0.01). Histologic and ultrastructural studies showed better preservation in group I than in groups II, III, and IV. We conclude that the new ET-Kyoto solution provides enhanced 30-hour lung preservation.

Opposite Roles for p38MAPK-Driven Responses and Reactive Oxygen Species in the Persistence and Resolution of Radiation-Induced Genomic Instability

PubMed Central

Werner, Erica; Wang, Huichen; Doetsch, Paul W.

2014-01-01

We report the functional and temporal relationship between cellular phenotypes such as oxidative stress, p38MAPK-dependent responses and genomic instability persisting in the progeny of cells exposed to sparsely ionizing low-Linear Energy Transfer (LET) radiation such as X-rays or high-charge and high-energy (HZE) particle high-LET radiation such as 56Fe ions. We found that exposure to low and high-LET radiation increased reactive oxygen species (ROS) levels as a threshold-like response induced independently of radiation quality and dose. This response was sustained for two weeks, which is the period of time when genomic instability is evidenced by increased micronucleus formation frequency and DNA damage associated foci. Indicators for another persisting response sharing phenotypes with stress-induced senescence, including beta galactosidase induction, increased nuclear size, p38MAPK activation and IL-8 production, were induced in the absence of cell proliferation arrest during the first, but not the second week following exposure to high-LET radiation. This response was driven by a p38MAPK-dependent mechanism and was affected by radiation quality and dose. This stress response and elevation of ROS affected genomic instability by distinct pathways. Through interference with p38MAPK activity, we show that radiation-induced stress phenotypes promote genomic instability. In contrast, exposure to physiologically relevant doses of hydrogen peroxide or increasing endogenous ROS levels with a catalase inhibitor reduced the level of genomic instability. Our results implicate persistently elevated ROS following exposure to radiation as a factor contributing to genome stabilization. PMID:25271419

Survival with 98% methemoglobin levels in a school-aged child during the "festival of colors".

PubMed

Sankar, Jhuma; Devangare, Shashikant; Dubey, N K

2013-10-01

Methemoglobin levels more than 70% have almost always been reported to have been fatal. The case of a 4-year-old boy who survived with methemoglobin levels of 98% is presented here. He was brought to the emergency department with complaints of vomiting, pain abdomen, and altered sensorium following accidental ingestion of paint thinner mixed with "Holi" colors. On examination, the child was in altered sensorium, cyanosed with saturations of 55%, who did not respond despite positive pressure ventilation with 100% oxygen. A possibility of toxic methemoglobinemia was considered and confirmed by finding of elevated methemoglobin levels of 98%. The child survived with definitive therapy with methylene blue and aggressive goal-directed approach.

Regulatory Mechanisms Involved in the Expression of Brain-Derived Neurotrophic Factor and Glial Cell Line-Derived Neurotrophic Factor

DTIC Science & Technology

1996-03-01

neurotoxic dopamine analog that is taken up by nigral dopaminergic cells where it is metabolized to highly reactive oxygen free radicals that cause ...brain regions is elevated after other types of brain insults, including ischemia and hypoglycemia (see Lindvall et al. 1994 for review). Lindvall et a1...with kainic acid were also reported. These investigators also reported significant increases in BDNF mRNA levels in cultures of neonatal astrocytes

Comparative genomic analysis as a tool for biologicaldiscovery

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nobrega, Marcelo A.; Pennacchio, Len A.

2003-03-30

Biology is a discipline rooted in comparisons. Comparative physiology has assembled a detailed catalogue of the biological similarities and differences between species, revealing insights into how life has adapted to fill a wide-range of environmental niches. For example, the oxygen and carbon dioxide carrying capacity of vertebrate has evolved to provide strong advantages for species respiring at sea level, at high elevation or within water. Comparative- anatomy, -biochemistry, -pharmacology, -immunology and -cell biology have provided the fundamental paradigms from which each discipline has grown.

Ignition and Combustion Characteristics of Pure Bulk Metals: Normal-Gravity Test Results

NASA Technical Reports Server (NTRS)

Abbud-Madrid, A.; Fiechtner, G. J.; Branch, M. C.; Daily, J. W.

1994-01-01

An experimental apparatus has been designed for the study of bulk metal ignition under elevated, normal and reduced gravity environments. The present work describes the technical characteristics of the system, the analytical techniques employed, the results obtained from the ignition of a variety of metals subjected to normal gravity conditions and the first results obtained from experiments under elevated gravity. A 1000 W xenon short-arc lamp is used to irradiate the top surface of a cylindrical metal specimen 4 mm in diameter and 4 mm high in a quiescent pure-oxygen environment at 0.1 MPa. Iron, titanium, zirconium, magnesium, zinc, tin, and copper specimens are investigated. All these metals exhibit ignition and combustion behavior varying in strength and speed. Values of ignition temperatures below, above or in the range of the metal melting point are obtained from the temperature records. The emission spectra from the magnesium-oxygen gas-phase reaction reveals the dynamic evolution of the ignition event. Scanning electron microscope and x-ray spectroscopic analysis provide the sequence of oxide formation on the burning of copper samples. Preliminary results on the effect of higher-than-normal gravity levels on the ignition of titanium specimens is presented.

Genetic adaptations of the plateau zokor in high-elevation burrows.

PubMed

Shao, Yong; Li, Jin-Xiu; Ge, Ri-Li; Zhong, Li; Irwin, David M; Murphy, Robert W; Zhang, Ya-Ping

2015-11-25

The plateau zokor (Myospalax baileyi) spends its entire life underground in sealed burrows. Confronting limited oxygen and high carbon dioxide concentrations, and complete darkness, they epitomize a successful physiological adaptation. Here, we employ transcriptome sequencing to explore the genetic underpinnings of their adaptations to this unique habitat. Compared to Rattus norvegicus, genes belonging to GO categories related to energy metabolism (e.g. mitochondrion and fatty acid beta-oxidation) underwent accelerated evolution in the plateau zokor. Furthermore, the numbers of positively selected genes were significantly enriched in the gene categories involved in ATPase activity, blood vessel development and respiratory gaseous exchange, functional categories that are relevant to adaptation to high altitudes. Among the 787 genes with evidence of parallel evolution, and thus identified as candidate genes, several GO categories (e.g. response to hypoxia, oxygen homeostasis and erythrocyte homeostasis) are significantly enriched, are two genes, EPAS1 and AJUBA, involved in the response to hypoxia, where the parallel evolved sites are at positions that are highly conserved in sequence alignments from multiple species. Thus, accelerated evolution of GO categories, positive selection and parallel evolution at the molecular level provide evidences to parse the genetic adaptations of the plateau zokor for living in high-elevation burrows.

Behaviour during elevated water temperatures: can physiology explain movement of juvenile Atlantic salmon to cool water?

PubMed

Breau, Cindy; Cunjak, Richard A; Peake, Stephan J

2011-07-01

1. Temperature governs most physiological processes in animals. Ectotherms behaviourally thermoregulate by selecting habitats with temperatures regulating their body temperature for optimal physiological functioning. However, ectotherms can experience temperature extremes forcing the organisms to seek temperature refuge. 2. Fish actively avoid potentially lethal temperatures by moving to cool-water sites created by inflowing tributaries and groundwater seeps. Juvenile Atlantic salmon (Salmo salar) of different age classes exhibit different behavioural responses to elevated temperatures (>23 °C). Yearling (1+) and 2-year-old (2+) Atlantic salmon often cease feeding, abandon territorial behaviour and swim continuously in aggregations in cool-water sites; whereas young-of-the-year (0+) fish continue defending territories and foraging. 3. This study determined whether the behavioural shift in older individuals (2+) occurred when basal metabolic rate, driven by increasing water temperature, reached the maximum metabolic rate such that anaerobic pathways were recruited to provide energy to support vital processes. Behaviour (feeding and stress responses), oxygen consumption, muscle lactate and glycogen, and circulating blood lactate and glucose concentrations were measured in wild 0+ and 2+ Atlantic salmon acclimated to water temperatures between 16 and 28 °C. 4. Results indicate that oxygen consumption of the 2+ fish increased with temperature and reached a plateau at 24 °C, a temperature that corresponded to cessation of feeding and a significant increase in muscle and blood lactate levels. By contrast, oxygen consumption in 0+ fish did not reach a plateau, feeding continued and muscle lactate did not increase, even at the highest temperatures tested (28 °C). 5. To conclude, the experiment demonstrated that the 0+ and 2+ fish had different physiological responses to the elevated water temperatures. The results suggest that wild 2+ Atlantic salmon employ behavioural responses (e.g. movement to cool-water sites) at elevated temperatures in an effort to mitigate physiological imbalances associated with an inability to support basal metabolism through aerobic metabolic processes. © 2011 The Authors. Journal of Animal Ecology © 2011 British Ecological Society.

Impact of Trans-Resveratrol-Sulfates and -Glucuronides on Endothelial Nitric Oxide Synthase Activity, Nitric Oxide Release and Intracellular Reactive Oxygen Species

PubMed Central

Ladurner, Angela; Schachner, Daniel; Schueller, Katharina; Pignitter, Marc; Heiss, Elke H.; Somoza, Veronika; Dirsch, Verena M.

2015-01-01

Resveratrol (3,5,4′-trihydroxy-trans-stilbene) is a polyphenolic natural product mainly present in grape skin, berries and peanuts. In the vasculature resveratrol is thought to boost endothelial function by increasing endothelial nitric oxide synthase (eNOS) expression, by enhancing eNOS activity, and by reduction of reactive oxygen species (ROS) levels. Recent studies show that dietary resveratrol is metabolized in the liver and intestine into resveratrol-sulfate and -glucuronide derivatives questioning the relevance of multiple reported mechanistic in vitro data on resveratrol. In this study, we compare side by side different physiologically relevant resveratrol metabolites (resveratrol sulfates- and -glucuronides) and their parent compound in their influence on eNOS enzyme activity, endothelial NO release, and intracellular ROS levels. In contrast to resveratrol, none of the tested resveratrol metabolites elevated eNOS enzyme activity and endothelial NO release or affected intracellular ROS levels, leaving the possibility that not tested metabolites are active and able to explain in vivo findings. PMID:25329867

Evaluating Use of Environmental Flows to Aerate Streams by Modelling the Counterfactual Case.

PubMed

Stewardson, Michael J; Skinner, Dominic

2018-03-01

This paper evaluates an experimental environmental flow manipulation by modeling the counterfactual case that no environmental flow was applied. This is an alternate approach to evaluating the effect of an environmental flow intervention when a before-after or control-impact comparison is not possible. In this case, the flow manipulation is a minimum flow designed to prevent hypoxia in a weir on the low-gradient Broken Creek in south-eastern Australia. At low flows, low reaeration rates and high respiration rates associated with elevated organic matter loading in the weir pool can lead to a decline in dissolved oxygen concentrations with adverse consequences both for water chemistry and aquatic biota. Using a one dimensional oxygen balance model fitted to field measurements, this paper demonstrates that increased flow leads to increases in reaeration rates, presumably because of enhanced turbulence and hence mixing in the surface layers. By comparing the observed dissolved oxygen levels with the modeled counterfactual case, we show that the environmental flow was effective in preventing hypoxia.

[The effect of altered oxygen partial pressure on the resisitance to hypoxia and expression of oxygen-sensitive genes in Drosophila melanogaster].

PubMed

Berezovs'kyĭ, V Ia; Chaka, O H; Litovka, I H; Levashov, M I; Ianko, R V

2014-01-01

As a result of resistance test to hypoxia of Drosophilas melanogaster of Oregon strain, we identified a high resistance (Group II) and low resistance (Group III) subpopulations of flies. Flies from groups II and III were incubated in a constant normobaric hypoxia (Po2=62-64 mm Hg) for 10 generations. A highly resistant group (Group IV) were exposed to a shortterm anoxia (Po,=1,5 mm Hg, 5 min) every generation. Larvae from Groups II, III, and IV demonstrated significantly elevated levels of Sir and CG 14740 expression. Larvae from Group II had a significantly higher expression of CG 14740 compared to group III. The restitution time after exposure to anoxia was significantly reduced in Group II (on 31% of the control values) Our results suggest that long-term adaptation to low oxygen partial pressure of highly resistant Drosophila significantly reduces the time of restitution and increases the expression of Sir2 and CG14740 genes.

Evaluating Use of Environmental Flows to Aerate Streams by Modelling the Counterfactual Case

NASA Astrophysics Data System (ADS)

Stewardson, Michael J.; Skinner, Dominic

2018-03-01

This paper evaluates an experimental environmental flow manipulation by modeling the counterfactual case that no environmental flow was applied. This is an alternate approach to evaluating the effect of an environmental flow intervention when a before-after or control-impact comparison is not possible. In this case, the flow manipulation is a minimum flow designed to prevent hypoxia in a weir on the low-gradient Broken Creek in south-eastern Australia. At low flows, low reaeration rates and high respiration rates associated with elevated organic matter loading in the weir pool can lead to a decline in dissolved oxygen concentrations with adverse consequences both for water chemistry and aquatic biota. Using a one dimensional oxygen balance model fitted to field measurements, this paper demonstrates that increased flow leads to increases in reaeration rates, presumably because of enhanced turbulence and hence mixing in the surface layers. By comparing the observed dissolved oxygen levels with the modeled counterfactual case, we show that the environmental flow was effective in preventing hypoxia.

Paleosols as Archives of Environmental Change in Deep Time

NASA Astrophysics Data System (ADS)

Crowley, Quentin

2015-04-01

Paleosols develop at the geosphere-atmosphere interface and potentially provide an archive of environmental conditions at the time of their formation. Although paleosols from deep time can be difficult to recognize due to the masking of pedogenic features by metamorphism and deformation, they may record transient (i.e. time-dependent) events which are often difficult to recognize in other geological proxies. Paleosols from the Archean and Paleoproterozoic are rare and complex to study, but offer an opportunity to gain insight into what may be relatively short-scale temporal variations in the Earth's atmospheric composition. For instance, it is widely believed that atmospheric oxygen saturation rose from <10E-05 present atmospheric level (PAL) in the Archean to >10E-02 PAL at the Great Oxidation Event (GOE) at ca. 2.4 Ga. Until recently however, chemical or physical evidence from paleosols for earlier oxygenation events were generally thought to be lacking. Recent studies of paleosols from eastern India (Keonjhar Paleosol, Singhbhum Craton) and South Africa (Nsuze Paleosol, Kaapvaal Craton) have provided chemical evidence for transient Mesoarchean atmospheric oxygenation at ca. 3.0 Ga. These paleosols are considered to preserve the earliest known vestiges of terrestrial oxidative weathering, signifying a transient, early oxygen accumulation in the Earth's atmosphere. This has far-reaching implications from both atmospheric and biological evolutionary perspectives in that chemical signatures preserved in these Mesoarchean paleosols are thought to signify the presence of molecular oxygen at levels higher than those attributable to photo-dissociation of atmospheric water alone. Such elevated levels of atmospheric oxygen could only be due to the presence of a sufficiently large biomass of micro-organisms capable of oxidative photosynthesis. Although the Archean-Paleoproterozoic paleosol geological record is fragmentary and geochemical signatures are not necessarily straightforward to interpret, these paleosols provide an opportunity to study the nature and timing of atmospheric compositional changes at a crucial time in the Earth's evolutionary history.

In vivo Ca2+ buffering capacity and microvascular oxygen pressures following muscle contractions in diabetic rat skeletal muscles: fiber-type specific effects.

PubMed

Eshima, Hiroaki; Poole, David C; Kano, Yutaka

2015-07-15

In Type 1 diabetes, skeletal muscle resting intracellular Ca(2+) concentration ([Ca(2+)]i) homeostasis is impaired following muscle contractions. It is unclear to what degree this behavior is contingent upon fiber type and muscle oxygenation conditions. We tested the hypotheses that: 1) the rise in resting [Ca(2+)]i evident in diabetic rat slow-twitch (type I) muscle would be exacerbated in fast-twitch (type II) muscle following contraction; and 2) these elevated [Ca(2+)]i levels would relate to derangement of microvascular partial pressure of oxygen (PmvO2 ) rather than sarcoplasmic reticulum dysfunction per se. Adult male Wistar rats were divided randomly into diabetic (DIA: streptozotocin ip) and healthy (CONT) groups. Four weeks later extensor digitorum longus (EDL, predominately type II fibers) and soleus (SOL, predominately type I fibers) muscle contractions were elicited by continuous electrical stimulation (120 s, 100 Hz). Ca(2+) imaging was achieved using fura 2-AM in vivo (i.e., circulation intact). DIA increased fatigability in EDL (P < 0.05) but not SOL. In recovery, SOL [Ca(2+)]i either returned to its resting baseline within 150 s (CONT 1.00 ± 0.02 at 600 s) or was not elevated in recovery at all (DIA 1.03 ± 0.02 at 600 s, P > 0.05). In recovery, EDL CONT [Ca(2+)]i also decreased to values not different from baseline (1.06 ± 0.01, P > 0.05) at 600 s. In marked contrast, EDL DIA [Ca(2+)]i remained elevated for the entire recovery period (i.e., 1.23 ± 0.03 at 600 s, P < 0.05). The inability of [Ca(2+)]i to return to baseline in EDL DIA was not associated with any reduction of SR Ca(2+)-ATPase (SERCA) 1 or SERCA2 protein levels (both increased 30-40%, P < 0.05). However, Pmv(O2) recovery kinetics were markedly slowed in EDL such that mean Pmv(O2) was substantially depressed (CONT 27.9 ± 2.0 vs. DIA 18.4 ± 2.0 Torr, P < 0.05), and this behavior was associated with the elevated [Ca(2+)]i. In contrast, this was not the case for SOL (P > 0.05) in that neither [Ca(2+)]i nor Pmv(O2) were deranged in recovery with DIA. In conclusion, recovery of [Ca(2+)]i homeostasis is impaired in diabetic rat fast-twitch but not slow-twitch muscle in concert with reduced Pmv(O2) pressures. Copyright © 2015 the American Physiological Society.

The effects of hyperthermia and hypoxia on ventilation during low-intensity steady-state exercise.

PubMed

Chu, Aaron L; Jay, Ollie; White, Matthew D

2007-01-01

This study assessed whether the elevated sensitivity of ventilation to hypoxia during exercise is accounted for by an elevation of esophageal temperature (T(es)). Eleven males volunteered for two exercise sessions on an underwater, head-out cycle ergometer at a steady-state rate of oxygen consumption (V(.)(O(2))) of approximately 0.87 l/min (SD 0.07). In one exercise session, 31.5 degrees C (SD 1.4) water held T(es) at a normothermic level of approximately 37.1 degrees C, and in the other exercise session, water at 38.2 degrees C (SD 0.1) maintained a hyperthermic T(es) of approximately 38.5 degrees C. After a 30-min rest and 20-min warm-up, exercising participants inhaled air for 10 min [Euoxia 1 (E1)], an isocapnic hypoxic gas mixture with 12% O(2) in N(2) (H1) for the next 10 min and air again [Euoxia 2 (E2)] for the last 10 min. A significant increase in V(.)(E) during all hyperthermia conditions (0.01< P < 0.048) was evident; however, during hyperthermic hypoxia, there was a disproportionate and significant (P = 0.017) increase in V(.)(E) relative to normothermic hypoxia. This was the main explanation for a significant esophageal temperature and gas type interaction (P = 0.012) for V(.)(E). Significant effects of hyperthermia, isocapnic hypoxia, and their positive interaction remained evident after removing the influence of (V(.)(O(2))) on V(.)(E). Serum lactate and potassium concentrations, as well as hemoglobin oxygen saturation, were each not significantly different between normothermic and hyperthermic-hypoxic conditions. In conclusion, the elevated sensitivity of exercise ventilation to hypoxia during exertion appears to be modulated by elevations in esophageal temperature, potentially because of a temperature-mediated stimulation of the peripheral chemoreceptors.

Atmospheric Management for Closed Bioregenerative Life Support Systems

NASA Astrophysics Data System (ADS)

Wheeler, Raymond

Bioregenerative life support systems for future space missions will likely center on photosynthetic organisms, such as higher plants, that could produce biomass and oxygen, while removing CO2. When the systems are sized sufficiently to produce most of the food for the humans, they would also provide all of the oxygen and removal of CO2. But managing the atmosphere must consider the ratio of CO2 uptake and oxygen production of the plants (assimilation quotients), and the CO2 production and oxygen uptake by humans (respiration quotients). Both of these ratios are affected by the composition of the biomass being produced or consumed (e.g., CH2O, protein, and fat content), and other factors such the form of nitrogen cycling back to the photosynthetic organisms. Planting and harvest strategies must also be considered because of their direct effects on near term photosynthetic capacity. For example, staggered planting and harvest strategies could reduce the impacts on oxygen production within the system. Maintaining optimal concentrations of the CO2 will also be important for the plants, where maximum photosynthetic rates for most C3 plants occur when CO2 greater than 1000 ppm. But allowing CO2 to rise to super-elevated levels, such as greater than 5000 ppm may be undesirable, and could also increase water use. This latter effect of increased transpiration at super-elevated CO2 is poorly understood and needs further research. The plants and other living organisms will also produce a range of volatile organic compounds (VOCs), and these VOCs must be managed just like any other trace contaminants in human space habitats. For plants, ethylene control will be especially important because of its potent effects on plant growth and development. Ultimately, a combination of biological systems with some physico-chemical control capabilities will likely provide the best approach.

Escherichia coli avoids high dissolved oxygen stress by activation of SoxRS and manganese-superoxide dismutase.

PubMed

Baez, Antonino; Shiloach, Joseph

2013-03-12

High concentrations of reactive oxygen species (ROS) were reported to cause oxidative stress to E. coli cells associated with reduced or inhibited growth. The high ROS concentrations described in these reports were generated by exposing the bacteria to H2O2 and superoxide-generating chemicals which are non-physiological growth conditions. However, the effect of molecular oxygen on oxidative stress response has not been evaluated. Since the use of oxygen-enriched air is a common strategy to support high density growth of E. coli, it was important to investigate the effect of high dissolved oxygen concentrations on the physiology and growth of E. coli and the way it responds to oxidative stress. To determine the effect of elevated oxygen concentrations on the growth characteristics, specific gene expression and enzyme activity in E. coli, the parental and SOD-deficient strain were evaluated when the dissolved oxygen (dO2) level was increased from 30% to 300%. No significant differences in the growth parameters were observed in the parental strain except for a temporary decrease of the respiration and acetate accumulation profile. By performing transcriptional analysis, it was determined that the parental strain responded to the oxidative stress by activating the SoxRS regulon. However, following the dO2 switch, the SOD-deficient strain activated both the SoxRS and OxyR regulons but it was unable to resume its initial growth rate. The transcriptional analysis and enzyme activity results indicated that when E. coli is exposed to dO2 shift, the superoxide stress regulator SoxRS is activated and causes the stimulation of the superoxide dismutase system. This enables the E. coli to protect itself from the poisoning effects of oxygen. The OxyR protecting system was not activated, indicating that H2O2 did not increase to stressing levels.

Escherichia coli avoids high dissolved oxygen stress by activation of SoxRS and manganese-superoxide dismutase

PubMed Central

2013-01-01

Background High concentrations of reactive oxygen species (ROS) were reported to cause oxidative stress to E. coli cells associated with reduced or inhibited growth. The high ROS concentrations described in these reports were generated by exposing the bacteria to H2O2 and superoxide-generating chemicals which are non-physiological growth conditions. However, the effect of molecular oxygen on oxidative stress response has not been evaluated. Since the use of oxygen-enriched air is a common strategy to support high density growth of E. coli, it was important to investigate the effect of high dissolved oxygen concentrations on the physiology and growth of E. coli and the way it responds to oxidative stress. Results To determine the effect of elevated oxygen concentrations on the growth characteristics, specific gene expression and enzyme activity in E. coli, the parental and SOD-deficient strain were evaluated when the dissolved oxygen (dO2) level was increased from 30% to 300%. No significant differences in the growth parameters were observed in the parental strain except for a temporary decrease of the respiration and acetate accumulation profile. By performing transcriptional analysis, it was determined that the parental strain responded to the oxidative stress by activating the SoxRS regulon. However, following the dO2 switch, the SOD-deficient strain activated both the SoxRS and OxyR regulons but it was unable to resume its initial growth rate. Conclusion The transcriptional analysis and enzyme activity results indicated that when E. coli is exposed to dO2 shift, the superoxide stress regulator SoxRS is activated and causes the stimulation of the superoxide dismutase system. This enables the E. coli to protect itself from the poisoning effects of oxygen. The OxyR protecting system was not activated, indicating that H2O2 did not increase to stressing levels. PMID:23497217

Physiological oxygen concentration alters glioma cell malignancy and responsiveness to photodynamic therapy in vitro.

PubMed

Albert, Ina; Hefti, Martin; Luginbuehl, Vera

2014-11-01

The partial pressure of oxygen (pO2) in brain tumors ranges from 5 to 15%. Nevertheless, the majority of in vitro experiments with glioblastoma multiforme (GBM) cell lines are carried out under an atmospheric pO2 of 19 to 21%. Recently, 5-aminolevulinic acid (5-ALA), a precursor of protoporphyrin IX (PpIX), has been introduced to neurosurgery to allow for photodynamic diagnosis and photodynamic therapy (PDT) in high-grade gliomas. Here, we investigate whether low pO2 affects GBM cell physiology, PpIX accumulation, or PDT efficacy. GBM cell lines (U-87 MG and U-251 MG) were cultured under atmospheric (pO2  =  19%) and physiological (pO2  =  9%) oxygen concentrations. PpIX accumulation and localization were investigated, and cell survival and cell death were observed following in vitro PDT. A physiological pO2 of 9% stimulated GBM cell migration, increased hypoxia-inducible factor (HIF)-1 alpha levels, and elevated resistance to camptothecin in U-87 MG cells compared to cultivation at a pO2 of 19%. This oxygen reduction did not alter 5-ALA-induced intracellular PpIX accumulation. However, physiological pO2 changed the responsiveness of U-87 MG but not of U-251 MG cells to in vitro PDT. Around 20% more irradiation light was required to kill U-87 MG cells at physiological pO2, resulting in reduced lactate dehydrogenase (LDH) release (one- to two-fold) and inhibition of caspase 3 activation. Reduction of oxygen concentration from atmospheric to a more physiological level can influence the malignant behavior and survival of GBM cell lines after in vitro PDT. Therefore, precise oxygen concentration control should be considered when designing and performing experiments with GBM cells.

Endogenous CO monitoring in exhalation with tunable diode lasers: applications to clinical and biomedical diagnostics

NASA Astrophysics Data System (ADS)

Stepanov, Eugene V.; Zyrianov, Pavel V.; Miliaev, Valerii A.; Shulagin, Yurii A.; D'yachenko, Alexander I.

1999-07-01

Middle IR tunable diode lasers were applied to studies of pulmonary excretion of endogenous carbon monoxide (CO). Variations of the CO content level in exhaled air of healthy nonsmokers were investigated for different environmental conditions with the applied laser technique. Correlation of the obtained data with atmospheric CO contamination and elevated oxygen content were studied as well as diurnal variations of the endogenous CO in exhalation was observed. Criteria for correct conditions of the endogenous CO detection in breath could be derive don this basis. Developed laser approach and methods were applied for the analysis of the excreted CO level in different diseases like bronchial asthma, cystic fibrosis, idiopathic pulmonary fibrosis, chronic obstructive pulmonary disease, anemia and hepatitis. Laser based close-to-real-time monitoring of the endogenous CO elimination with breath in the course of different dynamic tests was demonstrated to be informative in studies of blood oxygen transport and pH variations in tissues for different challenges tests in human physiology.

Atherosclerotic renal artery stenosis is associated with elevated cell cycle arrest markers related to reduced renal blood flow and postcontrast hypoxia.

PubMed

Saad, Ahmed; Wang, Wei; Herrmann, Sandra M S; Glockner, James F; Mckusick, Michael A; Misra, Sanjay; Bjarnason, Haraldur; Lerman, Lilach O; Textor, Stephen C

2016-11-01

Atherosclerotic renal artery stenosis (ARAS) reduces renal blood flow (RBF), ultimately leading to kidney hypoxia and inflammation. Insulin-like growth factor binding protein-7 (IGFBP-7) and tissue inhibitor of metalloproteinases-2 (TIMP-2) are biomarkers of cell cycle arrest, often increased in ischemic conditions and predictive of acute kidney injury (AKI). This study sought to examine the relationships between renal vein levels of IGFBP-7, TIMP-2, reductions in RBF and postcontrast hypoxia as measured by blood oxygen level-dependent (BOLD) magnetic resonance imaging. Renal vein levels of IGFBP-7 and TIMP-2 were obtained in an ARAS cohort (n= 29) scheduled for renal artery stenting and essential hypertensive (EH) healthy controls (n = 32). Cortical and medullary RBFs were measured by multidetector computed tomography (CT) immediately before renal artery stenting and 3 months later. BOLD imaging was performed before and 3 months after stenting in all patients, and a subgroup (N = 12) underwent repeat BOLD imaging 24 h after CT/stenting to examine postcontrast/procedure levels of hypoxia. Preintervention IGFBP-7 and TIMP-2 levels were elevated in ARAS compared with EH (18.5 ± 2.0 versus 15.7 ± 1.5 and 97.4 ± 23.1 versus 62.7 ± 9.2 ng/mL, respectively; P< 0.0001); baseline IGFBP-7 correlated inversely with hypoxia developing 24 h after contrast injection (r = -0.73, P< 0.0001) and with prestent cortical blood flow (r = -0.59, P= 0.004). These data demonstrate elevated IGFBP-7 and TIMP-2 levels in ARAS as a function of the degree of reduced RBF. Elevated baseline IGFBP-7 levels were associated with protection against postimaging hypoxia, consistent with 'ischemic preconditioning'. Despite contrast injection and stenting, AKI in these high-risk ARAS subjects with elevated IGFBP-7/TIMP-2 was rare and did not affect long-term kidney function. © The Author 2016. Published by Oxford University Press on behalf of ERA-EDTA. All rights reserved.

[The role of neuroglobin in oxygen-glucose deprivation and reoxygenation-induced mitochondrial depolarization and reactive oxygen species production in SH-SY5Y cells].

PubMed

Deng, S Y; Ai, Y H; Zhang, L N; Wu, L; Chen, C X; Wang, Y M; Liu, Z Y; Huang, L; Peng, Q Y

2017-01-01

Objective: To investigate the role of neuroglobin (NGB) in oxygen-glucose deprivation and reoxygenation (OGD/R) induced mitochondrial depolarization and reactive oxygen species (ROS)production in a human neuroblastoma cell line (SH-SY5Y). Methods: SH-SY5Y cells were transfected with lentivirus to establish a stable cell line of NGB knockdown (KD). After treated with OGD/R, cells were collected at different time points to analyze NGB mRNA and protein levels. Furthermore, cells were stained with JC-1 and DCFH-DA to evaluate mitochondrial depolarization and ROS production by inverted fluorescence microscope. Also, to determine the neurotoxicity, we measured the lactate dehydrogenase(LDH)level in the cell culture medium. Results: After the treatment of OGD/R, the NGB mRNA and protein started to elevate and peak at 4 h and 8 h (2.04±0.35 fold, 1.69±0.18 fold). Compared with the vector group, NGB KD group had much more mitochondrial depolarization [JC-1 red/green (1.10±0.10) vs (1.46±0.11), P <0.05] and ROS production [DCFH-DA fluorescence (36.30±5.32) vs (16.26±2.97), P <0.05]. Furthermore, NGB KD groups had a higher level of LDH release [(63.42±6.14)%vs (49.65±5.09)%, P <0.05]. Conclusions: NGB plays an important role in the homeostasis of mitochondria. Knockdown of NGB results in increased mitochondrial depolarization, ROS production and neurotoxicity under hypoxia circumstances.

Production of nitric oxide using a microwave plasma torch and its application to fungal cell differentiation

NASA Astrophysics Data System (ADS)

Na, Young Ho; Kumar, Naresh; Kang, Min-Ho; Cho, Guang Sup; Choi, Eun Ha; Park, Gyungsoon; Uhm, Han Sup

2015-03-01

The generation of nitric oxide by a microwave plasma torch is proposed for its application to cell differentiation. A microwave plasma torch was developed based on basic kinetic theory. The analytical theory indicates that nitric oxide density is nearly proportional to oxygen molecular density and that the high-temperature flame is an effective means of generating nitric oxide. Experimental data pertaining to nitric oxide production are presented in terms of the oxygen input in units of cubic centimeters per minute. The apparent length of the torch flame increases as the oxygen input increases. The various levels of nitric oxide are observed depending on the flow rate of nitrogen gas, the mole fraction of oxygen gas, and the microwave power. In order to evaluate the potential of nitric oxide as an activator of cell differentiation, we applied nitric oxide generated from the microwave plasma torch to a model microbial cell (Neurospora crassa: non-pathogenic fungus). Germination and hyphal differentiation of fungal cells were not dramatically changed but there was a significant increase in spore formation after treatment with nitric oxide. In addition, the expression level of a sporulation related gene acon-3 was significantly elevated after 24 h upon nitric oxide treatment. Increase in the level of nitric oxide, nitrite and nitrate in water after nitric oxide treatment seems to be responsible for activation of fungal sporulation. Our results suggest that nitric oxide generated by plasma can be used as a possible activator of cell differentiation and development.

The effect of biofiltration on red blood cells 2.3-diphosphoglycerate and pH.

PubMed

Umimoto, K; Hirai, Y; Hayashi, T; Tanaka, H

2000-12-01

To investigate the effect of biofiltration (BF) on the ability of blood to supply oxygen to the peripheral tissues, a 2 week crossover study was conducted with bicarbonate hemodialysis (BcHD) and BF using 5 male patients with diabetic renal failure as subjects. BcHD and BF were performed for 4 h and 3.5 h per session, respectively. Blood gases, the pH of red blood cells (RBC-pH), and 2. 3-diphosphoglycerate in RBC (RBC-2.3DPG) were measured during each treatment. After a 2 week BF treatment, the plasma HCO3- at the beginning of BF was significantly higher than that of BcHD (p < 0.01), and the blood pH improved with an elevated plasma bicarbonate level (p < 0.05). The RBC-pH at the beginning of BF was higher than that of BcHD (p < 0.05) although the RBC-pH at the end of both therapies increased to similar levels. The RBC-2.3DPG during BcHD remained unchanged, but during BF significantly increased (p < 0.05). Metabolic acidosis was significantly improved by BF with its effect reaching to the RBC intracellular level. The improved metabolic acidosis might occur as a result of the increase in RBC-2.3DPG during BF. This increase in RBC-2.3DPG has the effect of reducing the affinity of oxygen for hemoglobin and allows more oxygen to be delivered to the peripheral tissues although the increase in RBC-pH by dialysis restricts the dissociation of oxygen from hemoglobin.

Cocaine Exposure Increases Blood Pressure and Aortic Stiffness via the miR-30c-5p-Malic Enzyme 1-Reactive Oxygen Species Pathway.

PubMed

Zhu, Wei; Wang, Huilan; Wei, Jianqin; Sartor, Gregory C; Bao, Michelle Meiqi; Pierce, Clay T; Wahlestedt, Claes R; Dykxhoorn, Derek M; Dong, Chunming

2018-04-01

Cocaine abuse increases the risk of cardiovascular mortality and morbidity; however, the underlying molecular mechanisms remain elusive. By using a mouse model for cocaine abuse/use, we found that repeated cocaine injection led to increased blood pressure and aortic stiffness in mice associated with elevated levels of reactive oxygen species (ROS) in the aortas, a phenomenon similar to that observed in hypertensive humans. This ROS elevation was correlated with downregulation of Me1 (malic enzyme 1), an important redox molecule that counteracts ROS generation, and upregulation of microRNA (miR)-30c-5p that targets Me1 expression by directly binding to its 3'UTR (untranslated region). Remarkably, lentivirus-mediated overexpression of miR-30c-5p in aortic smooth muscle cells recapitulated the effect of cocaine on Me1 suppression, which in turn led to ROS elevation. Moreover, in vivo silencing of miR-30c-5p in smooth muscle cells resulted in Me1 upregulation, ROS reduction, and significantly suppressed cocaine-induced increases in blood pressure and aortic stiffness-a similar effect to that produced by treatment with the antioxidant N-acetyl cysteine. Discovery of this novel cocaine-↑miR-30c-5p-↓Me1-↑ROS pathway provides a potential new therapeutic avenue for treatment of cocaine abuse-related cardiovascular disease. © 2018 American Heart Association, Inc.

Device for measuring the total concentration of oxygen in gases

DOEpatents

Isaacs, Hugh S.; Romano, Anthony J.

1977-01-01

This invention provides a CO equilibrium in a device for measuring the total concentration of oxygen impurities in a fluid stream. To this end, the CO equilibrium is produced in an electrochemical measuring cell by the interaction of a carbon element in the cell with the chemically combined and uncombined oxygen in the fluid stream at an elevated temperature.

Positron beam study of indium tin oxide films on GaN

NASA Astrophysics Data System (ADS)

Cheung, C. K.; Wang, R. X.; Beling, C. D.; Djurisic, A. B.; Fung, S.

2007-02-01

Variable energy Doppler broadening spectroscopy has been used to study open-volume defects formed during the fabrication of indium tin oxide (ITO) thin films grown by electron-beam evaporation on n-GaN. The films were prepared at room temperature, 200 and 300 °C without oxygen and at 200 °C under different oxygen partial pressures. The results show that at elevated growth temperatures the ITO has fewer open volume sites and grows with a more crystalline structure. High temperature growth, however, is not sufficient in itself to remove open volume defects at the ITO/GaN interface. Growth under elevated temperature and under partial pressure of oxygen is found to further reduce the vacancy type defects associated with the ITO film, thus improving the quality of the film. Oxygen partial pressures of 6 × 10-3 mbar and above are found to remove open volume defects associated with the ITO/GaN interface. The study suggests that, irrespective of growth temperature and oxygen partial pressure, there is only one type of defect in the ITO responsible for trapping positrons, which we tentatively attribute to the oxygen vacancy.

[Diagnostic importance of the alveolar-arterial oxygen gradient].

PubMed

Weinans, Marije A E; Drost-de Klerck, Amanda M; ter Maaten, Jan C

2012-01-01

The alveolar-arterial (A-a) oxygen gradient is the difference between the partial pressure of oxygen in the alveoli and the partial pressure of arterial oxygen and can be elevated in the case of pulmonary disease. We describe a 41-year-old patient with pneumonia who presented with abdominal pain, in whom calculation of the A-a gradient could have led to earlier diagnosis. The A-a oxygen gradient is mainly of diagnostic importance and the presented nomogram allows easy and quick interpretation. This might lead to a more frequent use of the A-a oxygen gradient in the future.

Influence of the pineal gland and melatonin on blood flow and evaporative water loss during heat stress in rats.

PubMed

Harlow, H J

1987-01-01

Plasma melatonin levels of laboratory rats were elevated both during acute heat exposure (43 degrees C for 40 min) and chronic exposure (33 degrees C for 17 days) suggesting a possible correlation between melatonin and thermoregulatory mechanisms. Pinealectomy reduced the nighttime elevation in oxygen consumption and evaporative water loss. In addition, pinealectomized animals exhibited a significantly lower cutaneous evaporative water loss both at night and during the day when exposed to an acute heat exposure of 38 degrees C for 45 min. Pinealectomy elevated the blood pressure over the control group whereas melatonin infusion depressed the blood pressure without altering the cardiac output. This relationship implies an action by melatonin on the peripheral vasculature. In support of this conclusion, melatonin pretreatment tended to dampen the vasopressive effect of infused norepinephrine. These data, therefore, suggest a role of the pineal gland and melatonin in thermoregulation through an influence on the cardiovascular system and evaporative water loss.

Examining the relationships between egg cortisol and oxidative stress in developing wild sockeye salmon (Oncorhynchus nerka).

PubMed

Taylor, Jessica J; Sopinka, Natalie M; Wilson, Samantha M; Hinch, Scott G; Patterson, David A; Cooke, Steven J; Willmore, William G

2016-10-01

Maternally-derived hormones in oocytes, such as glucocorticoids (GCs), play a crucial role in embryo development in oviparous taxa. In fishes, maternal stressor exposure increases circulating and egg cortisol levels, the primary GC in fishes, as well as induces oxidative stress. Elevated egg cortisol levels modify offspring traits but whether maternal oxidative stress correlates with circulating and egg cortisol levels, and whether maternal/egg cortisol levels correlate with offspring oxidative stress have yet to be determined. The objective of this study was to examine the relationships among maternal and egg cortisol, and maternal and offspring oxidative stress to provide insight into the potential intergenerational effects of stressor exposure in sockeye salmon (Oncorhynchus nerka). Antioxidant concentration and oxidative stress were measured in maternal tissues (plasma, brain, heart and liver) as well as offspring developmental stages (pre-fertilization, 24h post-fertilization, eyed, and hatch), and were compared to both naturally-occurring and experimentally-elevated (via cortisol egg bath) levels of cortisol in eggs. Oxygen radical absorptive capacity of tissues from maternal sockeye salmon was measured spectrophotometrically and was not correlated with maternal or egg cortisol concentrations. Also, naturally-occurring and experimentally-elevated cortisol levels in eggs (to mimic maternal stress) did not affect oxidative stress or antioxidant capacity of the offspring. We conclude that the metrics of maternal stress examined in sockeye salmon (i.e., maternal/egg cortisol, maternal oxidative stress) are independent of each other, and that egg cortisol content does not influence offspring oxidative stress. Copyright © 2016 Elsevier Inc. All rights reserved.

PP043. Oxidative stress in the maternal body also affects the fetus in preeclamptic women with fetal growth restriction.

PubMed

Watanabe, Kazushi; Iwasaki, Ai; Mori, Toshitaka; Kimura, Chiharu; Matsushita, Hiroshi; Shinohara, Koichi; Wakatsuki, Akihiko

2013-04-01

The purpose of the present study was to determine whether oxidative stress occurring in the maternal body also affects the fetus in preeclamptic women with FGR. We ∥@consecutively recruited 17 preeclamptic women with FGR, 16 preeclamptic women without FGR, and 16 healthy pregnant women with uncomplicated pregnancy. We measured concentrations of derivatives of reactive oxygen metabolites (d-ROMs) as a marker of oxygen free radicals in a maternal vein, umbilical artery, and umbilical vein. ∥@Maternal d-ROM levels were higher in preeclamptic groups compared to the control group. Umbilical artery and vein d-ROM levels were elevated in preeclamptic women with FGR compared to the control group. Umbilical artery d-ROM levels were significantly higher than in the vein in preeclamptic women with FGR, but not in those without FGR. Umbilical arterial blood pH was significantly lower in preeclamptic women with FGR. The partial pressure of oxygen (PaO2) in umbilical arterial blood tended to be lower in preeclamptic women with FGR (p=0.08). The partial pressure of carbon dioxide (PaCO2) in umbilical arterial blood was significantly higher in preeclamptic women with FGR. These results indicate that oxidative stress occurring in the maternal body also affects the fetus in preeclamptic women with FGR. Copyright © 2013. Published by Elsevier B.V.

Oxygen vacancies dependent phase transition of Y2O3 films

NASA Astrophysics Data System (ADS)

Yu, Pengfei; Zhang, Kan; Huang, Hao; Wen, Mao; Li, Quan; Zhang, Wei; Hu, Chaoquan; Zheng, Weitao

2017-07-01

Y2O3 films have great application potential in high-temperature metal matrix composite and nuclear engineering, used as interface diffusion and reaction barrier coating owing to their excellent thermal and chemical stability, high melting point and extremely negative Gibbs formation energy, and thus their structural and mechanical properties at elevated temperature are especially important. Oxygen vacancies exist commonly in yttrium oxide (Y2O3) thin films and act strongly on the phase structure and properties, but oxygen vacancies dependent phase transition at elevated temperature has not been well explored yet. Y2O3 thin films with different oxygen vacancy concentrations have been achieved by reactive sputtering through varying substrate temperature (Ts), in which oxygen vacancies increase monotonously with increasing Ts. For as-deposited Y2O3 films, oxygen vacancies present at high Ts can promote the nucleation of monoclinic phase, meanwhile, high Ts can induce the instability of monoclinic phase. Thus their competition results in forming mixed phases of cubic and monoclinic at high Ts. During vacuum annealing at 1000 °C, a critical oxygen vacancy concentration is observed, below which phase transition from monoclinic to cubic takes place, and above which phase transfer from monoclinic to the oxygen defective phase (ICDD file no. 39-1063), accompanying by stress reversal from compressive to tensile and maintenance of high hardness.

Spatial contrast sensitivity at twilight: luminance, monocularity, and oxygenation.

PubMed

Connolly, Desmond M

2010-05-01

Visual performance in dim light is compromised by lack of oxygen (hypoxia). The possible influence of altered oxygenation on foveal contrast sensitivity under mesopic (twilight) viewing conditions is relevant to aircrew flying at night, including when using night vision devices, but is poorly documented. Foveal contrast sensitivity was measured binocularly and monocularly in 12 subjects at 7 spatial frequencies, ranging from 0.5 to approximately 16 cycles per degree, using sinusoidal Gabor patch gratings. Hypoxic performance breathing 14.1% oxygen, equivalent to altitude exposure at 3048 m (10,000 ft), was compared with breathing air at sea level (normoxia) at low photopic (28 cd x m(-2)), borderline upper mesopic (approximately 2.1 cd x m(-2)) and midmesopic (approximately 0.26 cd x m(-2)) luminance. Mesopic performance was also assessed breathing 100% oxygen (hyperoxia). Typical 'inverted U' log/log plots of the contrast sensitivity function were obtained, with elevated thresholds (reduced sensitivity) at lower luminance. Binocular viewing enhanced sensitivity by a factor approximating square root of 2 for most conditions, supporting neural summation of the contrast signal, but had greater influence at the lowest light level and highest spatial frequencies (8.26 and 16.51 cpd). Respiratory challenges had no effect. Contrast sensitivity is poorer when viewing monocularly and especially at midmesopic luminance, with relevance to night flying. The foveal contrast sensitivity function is unaffected by respiratory disturbance when twilight conditions favor cone vision, despite known effects on retinal illumination (pupil size). The resilience of the contrast sensitivity function belies the vulnerability of foveal low contrast acuity to mild hypoxia at mesopic luminance.

Noninvasive imaging of brain oxygen metabolism in children with primary nocturnal enuresis during natural sleep.

PubMed

Yu, Bing; Huang, Mingzhu; Zhang, Xu; Ma, Hongwei; Peng, Miao; Guo, Qiyong

2017-05-01

A series of studies have revealed that nocturnal enuresis is closely related to hypoxia in children with primary nocturnal enuresis (PNE). However, brain oxygen metabolism of PNE children has not been investigated before. The purpose of this study was to investigate changes in whole-brain cerebral metabolic rate of oxygen (CMRO 2 ), cerebral blood flow (CBF), and oxygen extraction fraction (OEF) in children suffering from PNE. We used the newly developed T2-relaxation-under-spin-tagging (TRUST) magnetic resonance imaging technique. Neurological evaluation, structural imaging, phase-contrast, and the TRUST imaging method were applied in children with PNE (n = 37) and healthy age- and sex-matched control volunteers (n = 39) during natural sleep to assess whole-brain CMRO 2 , CBF, OEF, and arousal from sleep scores. Results showed that whole-brain CMRO 2 and OEF values of PNE children were higher in controls, while there was no significant difference in CBF. Consequently, OEF levels of PNE children were increased to maintain oxygen supply. The elevation of OEF was positively correlated with the difficulty of arousal. Our results provide the first evidence that high oxygen consumption and high OEF values could make PNE children more susceptible to hypoxia, which may induce cumulative arousal deficits and make them more prone to nocturnal enuresis. Hum Brain Mapp 38:2532-2539, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

A unique mode of tissue oxygenation and the adaptive radiation of teleost fishes.

PubMed

Randall, D J; Rummer, J L; Wilson, J M; Wang, S; Brauner, C J

2014-04-15

Teleost fishes constitute 95% of extant aquatic vertebrates, and we suggest that this is related in part to their unique mode of tissue oxygenation. We propose the following sequence of events in the evolution of their oxygen delivery system. First, loss of plasma-accessible carbonic anhydrase (CA) in the gill and venous circulations slowed the Jacobs-Stewart cycle and the transfer of acid between the plasma and the red blood cells (RBCs). This ameliorated the effects of a generalised acidosis (associated with an increased capacity for burst swimming) on haemoglobin (Hb)-O2 binding. Because RBC pH was uncoupled from plasma pH, the importance of Hb as a buffer was reduced. The decrease in buffering was mediated by a reduction in the number of histidine residues on the Hb molecule and resulted in enhanced coupling of O2 and CO2 transfer through the RBCs. In the absence of plasma CA, nearly all plasma bicarbonate ultimately dehydrated to CO2 occurred via the RBCs, and chloride/bicarbonate exchange was the rate-limiting step in CO2 excretion. This pattern of CO2 excretion across the gills resulted in disequilibrium states for CO2 hydration/dehydration reactions and thus elevated arterial and venous plasma bicarbonate levels. Plasma-accessible CA embedded in arterial endothelia was retained, which eliminated the localized bicarbonate disequilibrium forming CO2 that then moved into the RBCs. Consequently, RBC pH decreased which, in conjunction with pH-sensitive Bohr/Root Hbs, elevated arterial oxygen tensions and thus enhanced tissue oxygenation. Counter-current arrangement of capillaries (retia) at the eye and later the swim bladder evolved along with the gas gland at the swim bladder. Both arrangements enhanced and magnified CO2 and acid production and, therefore, oxygen secretion to those specialised tissues. The evolution of β-adrenergically stimulated RBC Na(+)/H(+) exchange protected gill O2 uptake during stress and further augmented plasma disequilibrium states for CO2 hydration/dehydration. Finally, RBC organophosphates (e.g. NTP) could be reduced during hypoxia to further increase Hb-O2 affinity without compromising tissue O2 delivery because high-affinity Hbs could still adequately deliver O2 to the tissues via Bohr/Root shifts. We suggest that the evolution of this unique mode of tissue O2 transfer evolved in the Triassic/Jurassic Period, when O2 levels were low, ultimately giving rise to the most extensive adaptive radiation of extant vertebrates, the teleost fishes.

Studies on the temperature distribution of a thick film transcutaneous oxygen sensor and its thermal influences on oxygen measurement.

PubMed

Lam, Liza; Bilek, Jaromir; Atkinson, John

2006-11-01

The partial pressures of gases, namely oxygen and carbon dioxide, in the arterial blood are important parameters for doctors to determine the respiratory conditions of patients. Currently in practice, there are a number of ways to measure these parameters, one of which is transcutaneous blood gas monitoring. This technique is a popular noninvasive measurement method for obtaining fast and relatively accurate responses. In this investigation, thick film technology has been employed to develop an amperometric oxygen sensor which consists of a heating module to elevate the temperature at the skin surface to transcutaneous levels. The heating module includes a heating element and its temperature is regulated by a temperature control circuit. Using an infrared camera, the transient and steady-state temperature distributions as well as the stability of the heating element have been analysed. The influence of temperature on the oxygen sensing module is also studied. In addition, a three-dimensional theoretical model is established to evaluate the thermal response of the sensor and subsequently compared with the results from the practical prototype. With this model, the design stages can be simplified and future heating modules for transcutaneous sensors could be generated and improved more easily and effectively.

Endothelial microvesicles in hypoxic hypoxia diseases.

PubMed

Deng, Fan; Wang, Shuang; Xu, Riping; Yu, Wenqian; Wang, Xianyu; Zhang, Liangqing

2018-05-29

Hypoxic hypoxia, including abnormally low partial pressure of inhaled oxygen, external respiratory dysfunction-induced respiratory hypoxia and venous blood flow into the arterial blood, is characterized by decreased arterial oxygen partial pressure, resulting in tissue oxygen deficiency. The specific characteristics include reduced arterial oxygen partial pressure and oxygen content. Hypoxic hypoxia diseases (HHDs) have attracted increased attention due to their high morbidity and mortality and mounting evidence showing that hypoxia-induced oxidative stress, coagulation, inflammation and angiogenesis play extremely important roles in the physiological and pathological processes of HHDs-related vascular endothelial injury. Interestingly, endothelial microvesicles (EMVs), which can be induced by hypoxia, hypoxia-induced oxidative stress, coagulation and inflammation in HHDs, have emerged as key mediators of intercellular communication and cellular functions. EMVs shed from activated or apoptotic endothelial cells (ECs) reflect the degree of ECs damage, and elevated EMVs levels are present in several HHDs, including obstructive sleep apnoea syndrome and chronic obstructive pulmonary disease. Furthermore, EMVs have procoagulant, proinflammatory and angiogenic functions that affect the pathological processes of HHDs. This review summarizes the emerging roles of EMVs in the diagnosis, staging, treatment and clinical prognosis of HHDs. © 2018 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.

Promoted Metals Combustion at Ambient and Elevated Temperatures

NASA Technical Reports Server (NTRS)

Engel, Carl D.; Herald, Stephen D.; Davis, S. Eddie

2005-01-01

Promoted combustion testing of materials, Test 17 of NASA STD-6001, has been used to assess metal propensity to burn in oxygen rich environments. An igniter is used at the bottom end of a rod to promote ignition, and if combustion is sustained, the burning progresses from the bottom to the top of the rod. The physical mechanisms are very similar to the upward flammability test, Test 1 of NASA STD-6001. The differences are in the normal environmental range of pressures, oxygen content, and sample geometry. Upward flammability testing of organic materials can exhibit a significant transitional region between no burning to complete quasi-state burning. In this transitional region, the burn process exhibits a probabilistic nature. This transitional region has been identified for metals using the promoted combustion testing method at ambient initial temperatures. The work given here is focused on examining the transitional region and the quasi-steady burning region both at conventional ambient testing conditions and at elevated temperatures. A new heated promoted combustion facility and equipment at Marshall Space Flight Center have just been completed to provide the basic data regarding the metals operating temperature limits in contact with oxygen rich atmospheres at high pressures. Initial data have been obtained for Stainless Steel 304L, Stainless Steel 321, Haynes 214, and Inconel 718 at elevated temperatures in 100-percent oxygen atmospheres. These data along with an extended data set at ambient initial temperature test conditions are examined. The pressure boundaries of acceptable, non-burning usage is found to be lowered at elevated temperature.

Low earth orbit durability evaluation of Haynes 188 solar receiver material

NASA Technical Reports Server (NTRS)

De Groh, Kim K.; Rutledge, Sharon K.; Burke, Christopher A.; Dever, Therese M.; Olle, Raymond M.; Terlep, Judith A.

1992-01-01

The effects of elevated-temperature vacuum and elevated-temperature atomic oxygen exposure on the mass, surface chemistry, surface morphology, and optical properties of Haynes 188, a possible heat receiver material for space-based solar dynamic power systems, have been studied. Pristine and surface modified Haynes 188 were exposed to vacuum less than or equal to 10 exp -6 torr at 820 C for 5215.5 h, and to atomic oxygen in an air plasma asher at 34 and 827 C for fluences up to 5.6 x 10 exp 21 atoms/sq cm. Results obtained indicate that vacuum heat treatment caused surface morphology and chemistry changes with corresponding optical property changes. Atomic oxygen exposure caused optical property changes which diminished with time. Mass changes are considered to be negligible for both exposures.

Effect of Acute Dietary Nitrate Consumption on Oxygen Consumption During Submaximal Exercise in Hypobaric Hypoxia.

PubMed

Carriker, Colin R; Mermier, Christine M; Van Dusseldorp, Trisha A; Johnson, Kelly E; Beltz, Nicholas M; Vaughan, Roger A; McCormick, James J; Cole, Nathan H; Witt, Christopher C; Gibson, Ann L

2016-08-01

Reduced partial pressure of oxygen impairs exercise performance at altitude. Acute nitrate supplementation, at sea level, may reduce oxygen cost during submaximal exercise in hypobaric hypoxia. Therefore, we investigated the metabolic response during exercise at altitude following acute nitrate consumption. Ten well-trained (61.0 ± 7.4 ml/kg/min) males (age 28 ± 7 yr) completed 3 experimental trials (T1, T2, T3). T1 included baseline demographics, a maximal aerobic capacity test (VO2max) and five submaximal intensity cycling determination bouts at an elevation of 1600 m. A 4-day dietary washout, minimizing consumption of nitrate-rich foods, preceded T2 and T3. In a randomized, double-blind, placebo-controlled, crossover fashion, subjects consumed either a nitrate-depleted beetroot juice (PL) or ~12.8 mmol nitrate rich (NR) beverage 2.5 hr before T2 and T3. Exercise at 3500 m (T2 and T3) via hypobaric hypoxia consisted of a 5-min warm-up (25% of normobaric VO2max) and four 5-min cycling bouts (40, 50, 60, 70% of normobaric VO2max) each separated by a 4-min rest period. Cycling RPM and watts for each submaximal bout during T2 and T3 were determined during T1. Preexercise plasma nitrite was elevated following NR consumption compared with PL (1.4 ± 1.2 and 0.7 ± 0.3 uM respectively; p < .05). There was no difference in oxygen consumption (-0.5 ± 1.8, 0.1 ± 1.7, 0.7 ± 2.1, and 1.0 ± 3.0 ml/kg/min) at any intensity (40, 50, 60, 70% of VO2max, respectively) between NR and PL. Further, respiratory exchange ratio, oxygen saturation, heart rate and rating of perceived exertion were not different at any submaximal intensity between NR and PL either. Blood lactate, however, was reduced following NR consumption compared with PL at 40 and 60% of VO2max (p < .0.05). Our findings suggest that acute nitrate supplementation before exercise at 3500 m does not reduce oxygen cost but may reduce blood lactate accumulation at lower intensity workloads.

Combined effects of acidification and hypoxia on the estuarine ctenophore, Mnemiopsis leidyi

EPA Science Inventory

Estuaries are transitive zones which experience large fluctuations in environmental parameters (temperature, dissolved oxygen, pH, etc.). The interactive effects of reduced dissolved oxygen (DO) and elevated pCO2 on estuarine organisms is not currently well understood. Ctenophore...

The response of aircraft oxygen generators exposed to elevated temperatures

DOT National Transportation Integrated Search

2003-04-01

The purpose of this testing was to determine the temperatures that would cause self-activation of sodium chlorate oxygen generators. The data will be used to establish the degree of thermal protection that would be required to prevent the activation ...

Protein phosphatases 2A as well as reactive oxygen species involved in tributyltin-induced apoptosis in mouse livers.

PubMed

Zhang, Yali; Chen, Yonggang; Sun, Lijun; Liang, Jing; Guo, Zonglou; Xu, Lihong

2014-02-01

Tributyltin (TBT), a highly toxic environmental contaminant, has been shown to induce caspase-3-dependent apoptosis in human amniotic cells through protein phosphatase 2A (PP2A) inhibition and consequent JNK activation. This in vivo study was undertaken to further verify the results derived from our previous in vitro study. Mice were orally dosed with 0, 10, 20, and 60 mg/kg of body weight TBT, and levels of PP2A, reactive oxygen species (ROS), mitogen-activated protein kinase (MAPK), Bax/Bcl-2, and caspase-3 were detected in the mouse livers. Apoptosis was also evaluated using the TUNEL assay. The results showed that PP2A activity was inhibited, ROS levels were elevated, and MAPKs including ERK, JNK, and p38 were activated in mouse livers treated with the highest dose of TBT. Additionally, the ratio of Bax/Bcl-2 was increased, caspase-3 was activated, and apoptosis in mouse livers could be detected in the highest dose group. Therefore, a possible signaling pathway in TBT-induced apoptosis in mouse livers involves PP2A inhibition and ROS elevation serving a pivotal function as upstream activators of MAPKs; activation of MAPKs in turn leads to an increase in the Bax/Bcl-2 ratio, ultimately leading to the activation of caspase-3. The results give a comprehensive and novel description of the mechanism of TBT-induced toxicity. Copyright © 2011 Wiley Periodicals, Inc., A Wiley Company.

Preserved arterial flow secures hepatic oxygenation during haemorrhage in the pig

PubMed Central

Rasmussen, Allan; Skak, Claus; Kristensen, Michael; Ott, Peter; Kirkegaard, Preben; Secher, Niels H

1999-01-01

This study examined the extent of liver perfusion and its oxygenation during progressive haemorrhage. We examined hepatic arterial flow and hepatic oxygenation following the reduced portal flow during haemorrhage in 18 pigs. The hepatic surface oxygenation was assessed by near-infrared spectroscopy and the hepatic metabolism of oxygen, lactate and catecholamines determined the adequacy of the hepatic flow. Stepwise haemorrhage until circulatory collapse resulted in proportional reductions in cardiac output and in arterial, central venous and pulmonary wedge pressures. While heart rate increased, pulmonary arterial pressure remained stable. In addition, renal blood flow decreased, renal vascular resistance increased and there was elevated noradrenaline spill-over. Further, renal surface oxygenation was lowered from the onset of haemorrhage. Similarly, the portal blood flow was reduced in response to haemorrhage, and, as for the renal flow, the reduced splanchnic blood flow was associated with an elevated noradrenaline spill-over. In contrast, hepatic arterial blood flow was only slightly reduced by haemorrhage, and surface oxygenation did not change. The hepatic oxygen uptake was maintained until the blood loss represented more than 30 % of the estimated blood volume. At 30 % reduced blood volume, hepatic catecholamine uptake was reduced, and the lactate uptake approached zero. Subsequent reduction of cardiac output and portal blood flow elicited a selective dilatation of the hepatic arterial vascular bed. Due to this dilatation liver blood flow and hepatic cell oxygenation and metabolism were preserved prior to circulatory collapse. PMID:10087351

A Chinese herbal medicine, jia-wei-xiao-yao-san, prevents dimethylnitrosamine-induced hepatic fibrosis in rats.

PubMed

Chien, Shu-Chen; Chang, Wei-Chiao; Lin, Pu-Hua; Chang, Wei-Pin; Hsu, Shih-Chung; Chang, Jung-Chen; Wu, Ya-Chieh; Pei, Jin-Kuo; Lin, Chia-Hsien

2014-01-01

Jia-wei-xiao-yao-san (JWXYS) is a traditional Chinese herbal medicine that is widely used to treat neuropsychological disorders. Only a few of the hepatoprotective effects of JWXYS have been studied. The aim of this study was to investigate the hepatoprotective effects of JWXYS on dimethylnitrosamine- (DMN-) induced chronic hepatitis and hepatic fibrosis in rats and to clarify the mechanism through which JWXYS exerts these effects. After the rats were treated with DMN for 3 weeks, serum glutamic oxaloacetic transaminase (SGOT) and serum glutamic pyruvic transaminase (SGPT) levels were significantly elevated, whereas the albumin level decreased. Although DMN was continually administered, after the 3 doses of JWXYS were orally administered, the SGOT and SGPT levels significantly decreased and the albumin level was significantly elevated. In addition, JWXYS treatment prevented liver fibrosis induced by DMN. JWXYS exhibited superoxide-dismutase-like activity and dose-dependently inhibited DMN-induced lipid peroxidation and xanthine oxidase activity in the liver of rats. Our findings suggest that JWXYS exerts antifibrotic effects against DMN-induced chronic hepatic injury. The possible mechanism is at least partially attributable to the ability of JWXYS to inhibit reactive-oxygen-species-induced membrane lipid peroxidation.

Oxygen isotopes of marine mollusc shells record Eocene elevation change in the Pyrenees

NASA Astrophysics Data System (ADS)

Huyghe, Damien; Mouthereau, Frédéric; Emmanuel, Laurent

2012-09-01

Constraining paleoaltimetry of collisional orogens is critical to understand the dynamics of topographic evolution and climate/tectonics retroactions. Here, we use oxygen stable-isotope record on oyster shells, preserved in marine foreland deposits, to examine the past elevation of the Pyrenees during the Eocene. Our approach is based on the comparison with the Paris basin, an intracratonic basin not influenced by orogenic growth. The finding of a shift of 1.5‰ between 49 and 41 Ma, indicating more negative δ18Oc in the south Pyrenean foreland, is interpreted to reflect the inflow of river water sourced from higher elevation in the Pyrenees. To test this and provide paleoelevation estimate, we adopt a morphologic-hydrological model accounting for the hypsometry of drainage basin. Our best fitting model shows that the Pyrenees rose up to 2000 m. This indicates that the Pyrenees reached high elevation in the Eocene, thus providing new critical constraints on their long-term orogenic development. δ18O of marine mollusc shells are proved potentially attractive for paleoelevation studies, especially for mountain belts where elevated continental surfaces have not been preserved.

Physiological effects of environmental acidification in the deep-sea urchin Strongylocentrotus fragilis

NASA Astrophysics Data System (ADS)

Taylor, J. R.; Lovera, C.; Whaling, P. J.; Buck, K. R.; Pane, E. F.; Barry, J. P.

2014-03-01

Anthropogenic CO2 is now reaching depths over 1000 m in the Eastern Pacific, overlapping the Oxygen Minimum Zone (OMZ). Deep-sea animals are suspected to be especially sensitive to environmental acidification associated with global climate change. We have investigated the effects of elevated pCO2 and variable O2 on the deep-sea urchin Strongylocentrotus fragilis, a species whose range of 200-1200 m depth includes the OMZ and spans a pCO2 range of approx. 600-1200 μatm (approx. pH 7.6 to 7.8). Individuals were evaluated during two exposure experiments (1-month and 4 month) at control and three levels of elevated pCO2 at in situ O2 levels of approx. 10% air saturation. A treatment of control pCO2 at 100% air saturation was also included in experiment two. During the first experiment, perivisceral coelomic fluid (PCF) acid-base balance was investigated during a one-month exposure; results show S. fragilis has limited ability to compensate for the respiratory acidosis brought on by elevated pCO2, due in part to low non-bicarbonate PCF buffering capacity. During the second experiment, individuals were separated into fed and fasted experimental groups, and longer-term effects of elevated pCO2 and variable O2 on righting time, feeding, growth, and gonadosomatic index (GSI) were investigated for both groups. Results suggest that the acidosis found during experiment one does not directly correlate with adverse effects during exposure to realistic future pCO2 levels.

Effects of natural and human-induced hypoxia on coastal benthos

NASA Astrophysics Data System (ADS)

Levin, L. A.; Ekau, W.; Gooday, A. J.; Jorissen, F.; Middelburg, J. J.; Naqvi, S. W. A.; Neira, C.; Rabalais, N. N.; Zhang, J.

2009-10-01

Coastal hypoxia (defined here as <1.42 ml L-1; 62.5 μM; 2 mg L-1, approx. 30% oxygen saturation) develops seasonally in many estuaries, fjords, and along open coasts as a result of natural upwelling or from anthropogenic eutrophication induced by riverine nutrient inputs. Permanent hypoxia occurs naturally in some isolated seas and marine basins as well as in open slope oxygen minimum zones. Responses of benthos to hypoxia depend on the duration, predictability, and intensity of oxygen depletion and on whether H2S is formed. Under suboxic conditions, large mats of filamentous sulfide oxidizing bacteria cover the seabed and consume sulfide. They are hypothesized to provide a detoxified microhabitat for eukaryotic benthic communities. Calcareous foraminiferans and nematodes are particularly tolerant of low oxygen concentrations and may attain high densities and dominance, often in association with microbial mats. When oxygen is sufficient to support metazoans, small, soft-bodied invertebrates (typically annelids), often with short generation times and elaborate branchial structures, predominate. Large taxa are more sensitive than small taxa to hypoxia. Crustaceans and echinoderms are typically more sensitive to hypoxia, with lower oxygen thresholds, than annelids, sipunculans, molluscs and cnidarians. Mobile fish and shellfish will migrate away from low-oxygen areas. Within a species, early life stages may be more subject to oxygen stress than older life stages. Hypoxia alters both the structure and function of benthic communities, but effects may differ with regional hypoxia history. Human-caused hypoxia is generally linked to eutrophication, and occurs adjacent to watersheds with large populations or agricultural activities. Many occurrences are seasonal, within estuaries, fjords or enclosed seas of the North Atlantic and the NW Pacific Oceans. Benthic faunal responses, elicited at oxygen levels below 2 ml L-1, typically involve avoidance or mortality of large species and elevated abundances of enrichment opportunists, sometimes prior to population crashes. Areas of low oxygen persist seasonally or continuously beneath upwelling regions, associated with the upper parts of oxygen minimum zones (SE Pacific, W Africa, N Indian Ocean). These have a distribution largely distinct from eutrophic areas and support a resident fauna that is adapted to survive and reproduce at oxygen concentrations <0.5 ml L-1. Under both natural and eutrophication-caused hypoxia there is loss of diversity, through attrition of intolerant species and elevated dominance, as well as reductions in body size. These shifts in species composition and diversity yield altered trophic structure, energy flow pathways, and corresponding ecosystem services such as production, organic matter cycling and organic C burial. Increasingly the influences of nature and humans interact to generate or exacerbate hypoxia. A warmer ocean is more stratified, holds less oxygen, and may experience greater advection of oxygen-poor source waters, making new regions subject to hypoxia. Future understanding of benthic responses to hypoxia must be established in the context of global climate change and other human influences such as overfishing, pollution, disease, habitat loss, and species invasions.

The Calcium-Dependent Protein Kinase CPK28 Regulates Development by Inducing Growth Phase-Specific, Spatially Restricted Alterations in Jasmonic Acid Levels Independent of Defense Responses in Arabidopsis[OPEN

PubMed Central

Matschi, Susanne; Hake, Katharina; Herde, Marco; Hause, Bettina; Romeis, Tina

2015-01-01

Phytohormones play an important role in development and stress adaptations in plants, and several interacting hormonal pathways have been suggested to accomplish fine-tuning of stress responses at the expense of growth. This work describes the role played by the CALCIUM-DEPENDENT PROTEIN KINASE CPK28 in balancing phytohormone-mediated development in Arabidopsis thaliana, specifically during generative growth. cpk28 mutants exhibit growth reduction solely as adult plants, coinciding with altered balance of the phytohormones jasmonic acid (JA) and gibberellic acid (GA). JA-dependent gene expression and the levels of several JA metabolites were elevated in a growth phase-dependent manner in cpk28, and accumulation of JA metabolites was confined locally to the central rosette tissue. No elevated resistance toward herbivores or necrotrophic pathogens was detected for cpk28 plants, either on the whole-plant level or specifically within the tissue displaying elevated JA levels. Abolishment of JA biosynthesis or JA signaling led to a full reversion of the cpk28 growth phenotype, while modification of GA signaling did not. Our data identify CPK28 as a growth phase-dependent key negative regulator of distinct processes: While in seedlings, CPK28 regulates reactive oxygen species-mediated defense signaling; in adult plants, CPK28 confers developmental processes by the tissue-specific balance of JA and GA without affecting JA-mediated defense responses. PMID:25736059

Relative impact of H 2 O and O 2 in the oxidation of UO 2 powders from 50 to 300 °C

DOE Office of Scientific and Technical Information (OSTI.GOV)

Donald, Scott B.; Davisson, M. Lee; Dai, Zurong

Here, we studied the reaction of water and molecular oxygen with stoichiometric uranium dioxide (i.e. UO 2) powder at elevated temperature by high-resolution x-ray photoelectron spectroscopy (XPS), infrared (IR) spectroscopy, powder x-ray diffraction (XRD), and scanning electron microscopy (SEM). We observed and quatified oxidation resulting from the dissociative chemisorption of the adsorbing molecules and subsequent incorporation into the oxide lattice. Molecular oxygen was found to be a stronger oxidation agent than water at elevated temperatures but not at ambient.

Relative impact of H2O and O2 in the oxidation of UO2 powders from 50 to 300 °C

NASA Astrophysics Data System (ADS)

Donald, Scott B.; Davisson, M. Lee; Dai, Zurong; Roberts, Sarah K.; Nelson, Art J.

2017-12-01

The reaction of water and molecular oxygen with stoichiometric uranium dioxide (i.e. UO2) powder at elevated temperature was studied by high-resolution x-ray photoelectron spectroscopy (XPS), infrared (IR) spectroscopy, powder x-ray diffraction (XRD), and scanning electron microscopy (SEM). Oxidation resulting from the dissociative chemisorption of the adsorbing molecules and subsequent incorporation into the oxide lattice was observed and quantified. Molecular oxygen was found to be a stronger oxidation agent than water at elevated temperatures but not at ambient.

Relative impact of H 2 O and O 2 in the oxidation of UO 2 powders from 50 to 300 °C

DOE PAGES

Donald, Scott B.; Davisson, M. Lee; Dai, Zurong; ...

2017-10-04

Here, we studied the reaction of water and molecular oxygen with stoichiometric uranium dioxide (i.e. UO 2) powder at elevated temperature by high-resolution x-ray photoelectron spectroscopy (XPS), infrared (IR) spectroscopy, powder x-ray diffraction (XRD), and scanning electron microscopy (SEM). We observed and quatified oxidation resulting from the dissociative chemisorption of the adsorbing molecules and subsequent incorporation into the oxide lattice. Molecular oxygen was found to be a stronger oxidation agent than water at elevated temperatures but not at ambient.

The Biogeographic Pattern of Microbial Functional Genes along an Altitudinal Gradient of the Tibetan Pasture

PubMed Central

Qi, Qi; Zhao, Mengxin; Wang, Shiping; Ma, Xingyu; Wang, Yuxuan; Gao, Ying; Lin, Qiaoyan; Li, Xiangzhen; Gu, Baohua; Li, Guoxue; Zhou, Jizhong; Yang, Yunfeng

2017-01-01

As the highest place of the world, the Tibetan plateau is a fragile ecosystem. Given the importance of microbial communities in driving soil nutrient cycling, it is of interest to document the microbial biogeographic pattern here. We adopted a microarray-based tool named GeoChip 4.0 to investigate grassland microbial functional genes along an elevation gradient from 3200 to 3800 m above sea level open to free grazing by local herdsmen and wild animals. Interestingly, microbial functional diversities increase with elevation, so does the relative abundances of genes associated with carbon degradation, nitrogen cycling, methane production, cold shock and oxygen limitation. The range of Shannon diversities (10.27–10.58) showed considerably smaller variation than what was previously observed at ungrazed sites nearby (9.95–10.65), suggesting the important role of livestock grazing on microbial diversities. Closer examination showed that the dissimilarity of microbial community at our study sites increased with elevations, revealing an elevation-decay relationship of microbial functional genes. Both microbial functional diversity and the number of unique genes increased with elevations. Furthermore, we detected a tight linkage of greenhouse gas (CO2) and relative abundances of carbon cycling genes. Our biogeographic study provides insights on microbial functional diversity and soil biogeochemical cycling in Tibetan pastures. PMID:28659870

DOE Office of Scientific and Technical Information (OSTI.GOV)

Akter, Nusnin; Wang, Mengen; Zhong, Jian-Qiang

Copper is an important industrial catalyst. The ability to manipulate the oxidation state of copper clusters in a controlled way is critical to understanding structure–reactivity relations of copper catalysts at the molecular level. Experimentally, cupric oxide surfaces or even small domains can only be stabilized at elevated temperatures and in the presence of oxygen, as copper can be easily reduced under reaction conditions. Herein bilayer silica films grown on a metallic substrate are used to trap diluted copper oxide clusters. By combining in situ experiments with first principles calculations, it is found that the confined space created by the silicamore » film leads to an increase in the energy barrier for Cu diffusion. Dispersed copper atoms trapped by the silica film can be easily oxidized by surface oxygen chemisorbed on the metallic substrate, which results in the formation and stabilization of Cu 2+ cations.« less

Feed-derived volatile basic nitrogen increases reactive oxygen species production of blood leukocytes in lactating dairy cows.

PubMed

Tsunoda, Ei; Gross, Josef J; Kawashima, Chiho; Bruckmaier, Rupert M; Kida, Katsuya; Miyamoto, Akio

2017-01-01

The present study investigated over 9 months the changes of fermentative quality of total mixed rations (TMR) containing grass silage (GS) as a major component, associated with changes in the volatile basic nitrogen (VBN) levels in an experimental dairy farm. Effects of VBN levels in TMR on metabolic parameters, reactive oxygen species (ROS) production by blood polymorphonuclear leukocytes (PMNs) and conception rates for dairy cows were analyzed. According to VBN levels in TMR during survey periods, three distinct phases were identified; phase A with low VBN; phase B with high VBN; and phase C with mid-VBN. Metabolic parameters in blood were all within normal range. However, during phases B and C, nitrogen metabolic indices such as blood urea nitrogen and milk urea nitrogen showed higher levels compared to those in phase A, and a simultaneous increase in ROS production by blood PMNs and the load on hepatic function in metabolic parameters was observed in the cows with a lower conception rate. This suggests that feeding TMR with elevated VBN levels due to poor fermented GS results in stimulation of ROS production by PMNs by ammonia, and negatively affects metabolism and reproductive performance in lactating dairy cow. © 2016 Japanese Society of Animal Science.

Hemoglobin and 2,3-diphosphoglycerate levels in transfused dialysis patients with myocardial infarction.

PubMed

Crowley, J P; Valeri, C R; Metzger, J B; Pono, L; Chazan, J

1992-01-01

Thirty frequently transfused patients on long term hemodialysis were studied and a similar number of age and sex-matched patients who were infrequently transfused were used as a control group to ascertain the influence of a previous myocardial infarction (MI) on transfusion requirements. The frequency of previous MI on electrocardiogram (ECG) in the transfused and control groups was similar (40 percent and 37 percent, respectively). In frequently transfused dialysis patients with MI, the hemoglobin level (transfusion trigger) at which these patients were transfused was higher than that of frequently transfused patients without MI (8.3 +/- 1.5 g per dl vs. 6.9 +/- 1 g per dl, p less than 0.01) which indicated that patients without MI tolerated a greater degree of anemia than those with MI. The 2,3-diphosphoglycerate (2,3-DPG) levels were significantly elevated in all transfused patients when compared to matched controls. However, levels of 2,3-DPG were significantly higher in MI patients receiving frequent transfusions than in other transfused patients, suggesting oxygen demands may not have been fully met despite the frequent transfusions. The results suggest levels of 2,3-DPG deserve further study in relation to the adequacy of tissue oxygenation in anemic dialysis patients.

Controlled temperature expansion in oxygen production by molten alkali metal salts

DOEpatents

Erickson, Donald C.

1985-06-04

A continuous process is set forth for the production of oxygen from an oxygen containing gas stream, such as air, by contacting a feed gas stream with a molten solution of an oxygen acceptor to oxidize the acceptor and cyclically regenerating the oxidized acceptor by releasing oxygen from the acceptor wherein the oxygen-depleted gas stream from the contact zone is treated sequentially to temperature reduction by heat exchange against the feed stream so as to condense out entrained oxygen acceptor for recycle to the process, combustion of the gas stream with fuel to elevate its temperature and expansion of the combusted high temperature gas stream in a turbine to recover power.

Controlled temperature expansion in oxygen production by molten alkali metal salts

DOEpatents

Erickson, D.C.

1985-06-04

A continuous process is set forth for the production of oxygen from an oxygen containing gas stream, such as air, by contacting a feed gas stream with a molten solution of an oxygen acceptor to oxidize the acceptor and cyclically regenerating the oxidized acceptor by releasing oxygen from the acceptor wherein the oxygen-depleted gas stream from the contact zone is treated sequentially to temperature reduction by heat exchange against the feed stream so as to condense out entrained oxygen acceptor for recycle to the process, combustion of the gas stream with fuel to elevate its temperature and expansion of the combusted high temperature gas stream in a turbine to recover power. 1 fig.

Parental Effect of Long Acclimatization on Thermal Tolerance of Juvenile Sea Cucumber Apostichopus japonicus

PubMed Central

Dong, Yun-wei

2015-01-01

To evaluate the thermal resistance of marine invertebrates to elevated temperatures under scenarios of future climate change, it is crucial to understand parental effect of long acclimatization on thermal tolerance of offspring. To test whether there is parental effect of long acclimatization, adult sea cucumbers (Apostichopus japonicus) from the same broodstock were transplanted southward and acclimatized at high temperature in field mesocosms. Four groups of juvenile sea cucumbers whose parents experienced different durations of high temperature acclimatization were established. Upper thermal limits, oxygen consumption and levels of heat shock protein mRNA of juveniles was determined to compare thermal tolerance of individuals from different groups. Juvenile sea cucumbers whose parents experienced high temperature could acquire high thermal resistance. With the increase of parental exposure duration to high temperature, offspring became less sensitive to high temperature, as indicated by higher upper thermal limits (LT50), less seasonal variations of oxygen consumption, and stable oxygen consumption rates between chronic and acute thermal stress. The relatively high levels of constitutive expression of heat-shock proteins should contribute to the high thermal tolerance. Together, these results indicated that the existence of a parental effect of long acclimatization would increase thermal tolerance of juveniles and change the thermal sensitivity of sea cucumber to future climate change. PMID:26580550

Parental Effect of Long Acclimatization on Thermal Tolerance of Juvenile Sea Cucumber Apostichopus japonicus.

PubMed

Wang, Qing-Lin; Yu, Shan-Shan; Dong, Yun-Wei

2015-01-01

To evaluate the thermal resistance of marine invertebrates to elevated temperatures under scenarios of future climate change, it is crucial to understand parental effect of long acclimatization on thermal tolerance of offspring. To test whether there is parental effect of long acclimatization, adult sea cucumbers (Apostichopus japonicus) from the same broodstock were transplanted southward and acclimatized at high temperature in field mesocosms. Four groups of juvenile sea cucumbers whose parents experienced different durations of high temperature acclimatization were established. Upper thermal limits, oxygen consumption and levels of heat shock protein mRNA of juveniles was determined to compare thermal tolerance of individuals from different groups. Juvenile sea cucumbers whose parents experienced high temperature could acquire high thermal resistance. With the increase of parental exposure duration to high temperature, offspring became less sensitive to high temperature, as indicated by higher upper thermal limits (LT50), less seasonal variations of oxygen consumption, and stable oxygen consumption rates between chronic and acute thermal stress. The relatively high levels of constitutive expression of heat-shock proteins should contribute to the high thermal tolerance. Together, these results indicated that the existence of a parental effect of long acclimatization would increase thermal tolerance of juveniles and change the thermal sensitivity of sea cucumber to future climate change.

FirefOx Design Reference fO2 Sensor for Hot, Deep Atmospheres

NASA Astrophysics Data System (ADS)

Izenberg, N.; Papadakis, S.; Deglau, D.; Francomacaro, A. S.

2016-12-01

Understanding the composition of the lowest portion of Venus' atmosphere is critical to knowing the stable mineralogy of the rocks there. Oxygen gas is a critical trace component, with fugacity, or partial pressure, estimated in the range of 10-19 to 10-22 from early probe measurements down to 22km altitude (Pioneer Venus, Venera), chemical equilibrium measurements, and other modeling. "FirefOx" is a simple oxygen fugacity sensor with the express purpose of determining the partial pressure of oxygen in the lowest scale heights of the Venus atmosphere, and especially the lowest hundreds of meters; the surface atmosphere interface, where the atmosphere and surface move to thermodynamic equilibrium. Knowledge of the fO2 at the surface atmosphere interface is crucial to determining the stable mineralogy of surface materials (e.g. magnetite vs. hematite) and gas chemistry in the near-surface atmosphere FirefOx is a Metal/Metal Oxide oxygen fugacity sensor intended to be mounted on the outside of a Venus descent probe, with electronics housed inside a thermally controlled environment. The sole sensor capability is the precise, accurate detection of the partial pressure of oxygen gas (fO2) in the near-surface environment of Venus, at up to 95-bar pressure (predominantly CO2. Surface temperatures at mean planetary elevation are near 735 K, thus a required operational temperature range of 710-740 K covers a range of near-surface elevations. FirefOx system requirements are low ( 100-200 grams, mass, milliwatt power, several kilobytes total science data). A design reference sensor, composed of custom, Yittria-ZrO ceramic electrolyte, with an encapsulated Pd/PdO standard and patterned Pt electrodes has demonstrated scientifically useful signal-to-noise millivolt level potential at temperatures as low as 620 K, relatable to fO2 by a Nernst equation E = RT/4F ln(PO2/PrefO2) where E = open circuit potential across the sensor electrolyte, R = universal gas constant, T = temperature, F = Faraday constant, PrefO2 = reference oxygen pressure, and PO2 = unknown oxygen pressure of the outside environment. The FirefOx sensor shows promise for direct fO2 measurement on potential upcoming Venus in situ and other deep atmosphere probes.

Bringing organic carbon isotopes and phytoliths to the table as additional constraints on paleoelevation

NASA Astrophysics Data System (ADS)

Sheldon, N. D.; Cotton, J. M.; Hren, M. T.; Hyland, E. G.; Smith, S. Y.; Strömberg, C. A. E.

2015-12-01

A commonly used tool in paleotectonic and paleoaltimetry studies is the oxygen isotopic composition of authigenic carbonates formed that formed in lakes or soils, with both spatial (e.g., shoreline to mountain top) or temporally resolved records potentially providing constraints. However, in many cases there is a substantial spread in the oxygen isotope data for a given time period, often to the point of allowing for essentially any interpretation of the data depending upon how they have been used by the investigator. One potential way of distinguishing between different potential paleotectonic or paleoaltimetric interpretations is to use carbon isotope and plant microfossil (phytolith) analyses from the same paleosols to screen the oxygen isotope data by looking for evidence of evaporative enrichment. For example, if both inorganic (carbonate) and organic carbon isotopes are measured from the same paleosol, then in it possible to determine if the two isotope record equilibrium conditions or if they record disequilibrium driven by kinetic effects. In the former case, the oxygen isotope results can be considered reliable whereas in the latter case, the oxygen isotope results can be considered unreliable and could be culled from the interpretation. Similarly, because the distribution of C4 plants varies as a function of temperature and elevation, the presence/absence or abundance of C4 plant phytoliths, or of carbon isotope compositions that require a component of C4 vegetation can also be used to constrain paleoelevation by providing a maximum elevation constraint. Worked examples will include the late Miocene-Pliocene of Catamarca, Argentina, where phytoliths and organic carbon isotopes provide a maximum elevation constraint and can be used to demonstrate that oxygen isotopes do not provide a locally useful constraint on paleoelevation, and Eocene-Miocene of southwestern Montana where organic matter and phytoliths can be used to select between different potential uplift histories as indicated by pedogenic carbonate oxygen isotope data.

Testing metals and alloys for use in oxygen systems

NASA Technical Reports Server (NTRS)

Stoltzfus, Joel M.

1986-01-01

When oxygen is present in high concentrations or large quantities, as in oxygen-based life-support systems, the likelihood of combustion and the probable intensity of a conflagration increase, together with the severity of the damage caused. Even stainless steel will burn vigorously when ignited in a 1000-psi oxygen environment. The hazards involved in the use of oxygen increase with system operation at the elevated temperatures typical of propulsion systems. Fires in oxygen systems are generally catastrophic, causing a threat to life in manned vehicles. When mechanical components of a mechanism generate friction heat in the presence of oxygen, many commonly used metal alloys ignite and burn. Attention is presently given to frictional heating, particle impact, and flame propagation tests conducted in oxygen environments.

Generation of High Pressure Oxygen via Electrochemical Pumping in a Multi-stage Electrolysis Stack

NASA Technical Reports Server (NTRS)

Setlock, John A (Inventor); Green, Robert D (Inventor); Farmer, Serene (Inventor)

2016-01-01

An oxygen pump can produce high-purity high-pressure oxygen. Oxygen ions (O.sup.2-) are electrochemically pumped through a multi-stage electrolysis stack of cells. Each cell includes an oxygen-ion conducting solid-state electrolyte between cathode and anode sides. Oxygen dissociates into the ions at the cathode side. The ions migrate across the electrolyte and recombine at the anode side. An insulator is between adjacent cells to electrically isolate each individual cell. Each cell receives a similar volt potential. Recombined oxygen from a previous stage can diffuse through the insulator to reach the cathode side of the next stage. Each successive stage similarly incrementally pressurizes the oxygen to produce a final elevated pressure.

Generation of High Pressure Oxygen via Electrochemical Pumping in a Multi-Stage Electrolysis Stack

NASA Technical Reports Server (NTRS)

Setlock, John A (Inventor); Green, Robert D (Inventor); Farmer, Serene (Inventor)

2017-01-01

An oxygen pump can produce high-purity high-pressure oxygen. Oxygen ions (O(2-)) are electrochemically pumped through a multi-stage electrolysis stack of cells. Each cell includes an oxygen-ion conducting solid-state electrolyte between cathode and anode sides. Oxygen dissociates into the ions at the cathode side. The ions migrate across the electrolyte and recombine at the anode side. An insulator is between adjacent cells to electrically isolate each individual cell. Each cell receives a similar volt potential. Recombined oxygen from a previous stage can diffuse through the insulator to reach the cathode side of the next stage. Each successive stage similarly incrementally pressurizes the oxygen to produce a final elevated pressure.

Evaluation of submarine atmospheres: effects of carbon monoxide, carbon dioxide and oxygen on general toxicology, neurobehavioral performance, reproduction and development in rats. I. Subacute exposures.

PubMed

Hardt, Daniel J; James, R Arden; Gut, Chester P; McInturf, Shawn M; Sweeney, Lisa M; Erickson, Richard P; Gargas, Michael L

2015-02-01

The inhalation toxicity of submarine contaminants is of concern to ensure the health of men and women aboard submarines during operational deployments. Due to a lack of adequate prior studies, potential general, neurobehavioral, reproductive and developmental toxicity was evaluated in male and female rats exposed to mixtures of three critical submarine atmospheric components: carbon monoxide (CO) and carbon dioxide (CO2; levels elevated above ambient), and oxygen (O2; levels decreased below ambient). In a 14-day, 23 h/day, whole-body inhalation study of exposure to clean air (0.4 ppm CO, 0.1% CO2 and 20.6% O2), low-dose, mid-dose and high-dose gas mixtures (high dose of 88.4 ppm CO, 2.5% CO2 and 15.0% O2), no adverse effects on survival, body weight or histopathology were observed. Reproductive, developmental and neurobehavioral performance were evaluated after a 28-day exposure in similar atmospheres. No adverse effects on estrus phase, mating, gestation or parturition were observed. No developmental or functional deficits were observed in either exposed parents or offspring related to motor activity, exploratory behavior or higher-level cognitive functions (learning and memory). Only minimal effects were discovered in parent-offspring emotionality tests. While statistically significant increases in hematological parameters were observed in the offspring of exposed parents compared to controls, these parameters remained within normal clinical ranges for blood cells and components and were not considered adverse. In summary, subacute exposures to elevated concentrations of the submarine atmosphere gases did not affect the ability of rats to reproduce and did not appear to have any significant adverse health effects.

Microbial community functional structure in response to micro-aerobic conditions in sulfate-reducing sulfur-producing bioreactor.

PubMed

Yu, Hao; Chen, Chuan; Ma, Jincai; Xu, Xijun; Fan, Ronggui; Wang, Aijie

2014-05-01

Limited oxygen supply to anaerobic wastewater treatment systems had been demonstrated as an effective strategy to improve elemental sulfur (S(0)) recovery, coupling sulfate reduction and sulfide oxidation. However, little is known about the impact of dissolved oxygen (DO) on the microbial functional structures in these systems. We used a high throughput tool (GeoChip) to evaluate the microbial community structures in a biological desulfurization reactor under micro-aerobic conditions (DO: 0.02-0.33 mg/L). The results indicated that the microbial community functional compositions and structures were dramatically altered with elevated DO levels. The abundances of dsrA/B genes involved in sulfate reduction processes significantly decreased (p < 0.05, LSD test) at relatively high DO concentration (DO: 0.33 mg/L). The abundances of sox and fccA/B genes involved in sulfur/sulfide oxidation processes significantly increased (p < 0.05, LSD test) in low DO concentration conditions (DO: 0.09 mg/L) and then gradually decreased with continuously elevated DO levels. Their abundances coincided with the change of sulfate removal efficiencies and elemental sulfur (S(0)) conversion efficiencies in the bioreactor. In addition, the abundance of carbon degradation genes increased with the raising of DO levels, showing that the heterotrophic microorganisms (e.g., fermentative microorganisms) were thriving under micro-aerobic condition. This study provides new insights into the impacts of micro-aerobic conditions on the microbial functional structure of sulfate-reducing sulfur-producing bioreactors, and revealed the potential linkage between functional microbial communities and reactor performance. Copyright © 2014 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

Negative Regulation of Leptin-induced Reactive Oxygen Species (ROS) Formation by Cannabinoid CB1 Receptor Activation in Hypothalamic Neurons.

PubMed

Palomba, Letizia; Silvestri, Cristoforo; Imperatore, Roberta; Morello, Giovanna; Piscitelli, Fabiana; Martella, Andrea; Cristino, Luigia; Di Marzo, Vincenzo

2015-05-29

The adipocyte-derived, anorectic hormone leptin was recently shown to owe part of its regulatory effects on appetite-regulating hypothalamic neuropeptides to the elevation of reactive oxygen species (ROS) levels in arcuate nucleus (ARC) neurons. Leptin is also known to exert a negative regulation on hypothalamic endocannabinoid levels and hence on cannabinoid CB1 receptor activity. Here we investigated the possibility of a negative regulation by CB1 receptors of leptin-mediated ROS formation in the ARC. Through pharmacological and molecular biology experiments we report data showing that leptin-induced ROS accumulation is 1) blunted by arachidonyl-2'-chloroethylamide (ACEA) in a CB1-dependent manner in both the mouse hypothalamic cell line mHypoE-N41 and ARC neuron primary cultures, 2) likewise blocked by a peroxisome proliferator-activated receptor-γ (PPAR-γ) agonist, troglitazone, in a manner inhibited by T0070907, a PPAR-γ antagonist that also inhibited the ACEA effect on leptin, 3) blunted under conditions of increased endocannabinoid tone due to either pharmacological or genetic inhibition of endocannabinoid degradation in mHypoE-N41 and primary ARC neuronal cultures from MAGL(-/-) mice, respectively, and 4) associated with reduction of both PPAR-γ and catalase activity, which are reversed by both ACEA and troglitazone. We conclude that CB1 activation reverses leptin-induced ROS formation and hence possibly some of the ROS-mediated effects of the hormone by preventing PPAR-γ inhibition by leptin, with subsequent increase of catalase activity. This mechanism might underlie in part CB1 orexigenic actions under physiopathological conditions accompanied by elevated hypothalamic endocannabinoid levels. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

Effects of saturated palmitic acid and omega-3 polyunsaturated fatty acids on Sertoli cell apoptosis.

PubMed

Hu, Xuechun; Ge, Xie; Liang, Wei; Shao, Yong; Jing, Jun; Wang, Cencen; Zeng, Rong; Yao, Bing

2018-05-25

Obesity is believed to negatively affect male semen quality and is accompanied by dysregulation of free fatty acid (FFA) metabolism in plasma. However, the implication of dysregulated FFA on semen quality and the involvement of Sertoli cells remain unclear. In the present study, we report obesity decreased Sertoli cell viability through dysregulated FFAs. We observed an increased rate of apoptosis in Sertoli cells, accompanied with elevated FFA levels, in the testes of obese mice that were provided a high-fat diet (HFD). Moreover, the levels of reactive oxygen species were elevated. Furthermore, we demonstrated by in vitro assays that saturated palmitic acid (PA), which is the most common saturated FFA in plasma, led to decreased cell viability of TM4 Sertoli cells in a time- and dose-dependent manner. A similar finding was noted in primary mouse Sertoli cells. In contrast to saturated FFA, omega-3 (ω-3) polyunsaturated fatty acids (PUFAs) protected Sertoli cells from PA-induced lipotoxicity at the physiologically relevant levels. These results indicated that the lipotoxicity of saturated fatty acids might be the cause of obesity-induced Sertoli cell apoptosis, which leads to decreased semen quality. In addition, ω-3 PUFAs could be classified as protective FFAs. FFA: free fatty acid; HFD: high-fat diet; SD: standard diet; PA: palmitic acid; PUFA: polyunsaturated fatty acid; AI: apoptotic index; MTT: 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide; ROS: reactive oxygen species; HE: Hematoxylin and eosin; WT1: Wilm Tumor 1; NAFLD: non- alcoholic fatty liver disease; DCFH-DA: 2', 7' dichlorofluorescin diacetate; 36B4: acidic ribosomal phosphoprotein P0; SD: standard deviation; EPA: eicosapentaenoic acid; PI: propidium iodide; DHA: docosahexenoic acid.

Elevated Prostaglandin E Metabolites and Abnormal Plasma Fatty Acids at Baseline in Pediatric Cystic Fibrosis Patients: A Pilot Study

PubMed Central

O’Connor, Michael Glenn; Thomsen, Kelly; Brown, Rebekah F.; Laposata, Michael; Seegmiller, Adam

2016-01-01

Background Airway inflammation is a significant contributor to the morbidity of cystic fibrosis (CF) disease. One feature of this inflammation is the production of oxygenated metabolites, such as prostaglandins. Individuals with CF are known to have abnormal metabolism of fatty acids, typically resulting in reduced levels of linoleic acid (LA) and docosahexaenoic acid (DHA). Methods This is a randomized, double-blind, cross-over clinical trial of DHA supplementation with endpoints of plasma fatty acid levels and prostaglandin E metabolite (PGE-M) levels. Patients with CF age 6 to 18 years with pancreatic insufficiency were recruited. Each participant completed 3 four-week study periods: DHA at two different doses (high dose and low dose) and placebo with a minimum 4 week wash-out between each period. Blood, urine, and exhaled breath condensate (EBC) were collected at baseline and after each study period for measurement of plasma fatty acids as well as prostaglandin E metabolites. Results Seventeen participants were enrolled, and 12 participants completed all 3 study periods. Overall, DHA supplementation was well tolerated without significant adverse events. There was a significant increase in plasma DHA levels with supplementation, but no significant change in arachidonic acid (AA) or LA levels. However, at baseline, AA levels were lower and LA levels were higher than previously reported for individuals with CF. Urine PGE-M levels were elevated in the majority of participants at baseline, and while levels decreased with DHA supplementation, they also decreased with placebo. Conclusions Urine PGE-M levels are elevated at baseline in this cohort of pediatric CF patients, but there was no significant change in these levels with DHA supplementation compared to placebo. In addition, baseline plasma fatty acid levels for this cohort showed some difference to prior reports, including higher levels of LA and lower levels of AA, which may reflect changes in clinical care, and consequently warrants further investigation. PMID:27720040

Elevated prostaglandin E metabolites and abnormal plasma fatty acids at baseline in pediatric cystic fibrosis patients: a pilot study.

PubMed

O'Connor, Michael Glenn; Thomsen, Kelly; Brown, Rebekah F; Laposata, Michael; Seegmiller, Adam

2016-10-01

Airway inflammation is a significant contributor to the morbidity of cystic fibrosis (CF) disease. One feature of this inflammation is the production of oxygenated metabolites, such as prostaglandins. Individuals with CF are known to have abnormal metabolism of fatty acids, typically resulting in reduced levels of linoleic acid (LA) and docosahexaenoic acid (DHA). This is a randomized, double-blind, cross-over clinical trial of DHA supplementation with endpoints of plasma fatty acid levels and prostaglandin E metabolite (PGE-M) levels. Patients with CF age 6-18 years with pancreatic insufficiency were recruited. Each participant completed 3 four-week study periods: DHA at two different doses (high dose and low dose) and placebo with a minimum 4 week wash-out between each period. Blood, urine, and exhaled breath condensate (EBC) were collected at baseline and after each study period for measurement of plasma fatty acids as well as prostaglandin E metabolites. Seventeen participants were enrolled, and 12 participants completed all 3 study periods. Overall, DHA supplementation was well tolerated without significant adverse events. There was a significant increase in plasma DHA levels with supplementation, but no significant change in arachidonic acid (AA) or LA levels. However, at baseline, AA levels were lower and LA levels were higher than previously reported for individuals with CF. Urine PGE-M levels were elevated in the majority of participants at baseline, and while levels decreased with DHA supplementation, they also decreased with placebo. Urine PGE-M levels are elevated at baseline in this cohort of pediatric CF patients, but there was no significant change in these levels with DHA supplementation compared to placebo. In addition, baseline plasma fatty acid levels for this cohort showed some difference to prior reports, including higher levels of LA and lower levels of AA, which may reflect changes in clinical care, and consequently warrants further investigation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Dual-cycle ergometry as an exercise modality during prebreathe with 100 percent oxygen

NASA Technical Reports Server (NTRS)

Heaps, Cristine L.; Fischer, Michele D.; Webb, James T.

1994-01-01

In an effort to reduce prebreathe time requirements prior to extravehicular activities and high-altitude flights, a combined arm and leg exercise task proposes to enhance denitrogenation by incorporation of both upper and lower body musculature at a moderately high work intensity during prebreathe with 100% oxygen. Preliminary findings indicated peak oxygen consumption (VO2peak) levels attained on the dual-cycle ergometer do not differ significantly from those levels attained on the treadmill. Eight male subjects were exercised to VO2peak using leg-only cycle ergometry and dual-cycle ergometry on separate days. Preliminary data during dual-cycle ergometry showed arm work equaling 30% of the leg workrate at each stage of the incremental test resulted in arm fatigue in several subjects and a reduced VO2peak compared to dual-cycle ergometry with arm work at 20%. Thus, the 20% workrate was used during the dual-cycle VO2peak trial. On a third experimental day, subjects performed a 10 minute exercise test at a workrate required to elicit 75% of VO2peak for each subject on the dual-cycle ergometer. Blood lactate response to the exercise was monitored as an objective measure of fatigue. Peak VO2 levels attained on the leg-only and the dual-cycle ergometry tasks were not significantly different. Blood lactate levels were significantly elevated following the dual-cycle ergometry at 75% VO2peak. However, lactate levels show the expected rate of decline during recovery and, as demonstrated in the literature, should return to baseline levels within 30 minutes following exercise cessation. Thus, dual-cycle ergometry at 75% VO2peak appears to be a valid exercise for use during prebreathe and should not contribute to fatigue during subsequent EVA's.

HIGH ARSENIC CONCENTRATIONS AND ENRICHED SULFUR AND OXYGEN ISOTOPES IN A FRACTURED-BEDROCK GROUND-WATER SYSTEM

EPA Science Inventory

Elevated arsenic concentrations are coincident with enriched sulfur and oxygen isotopes of sulfate in bedrock ground water within Kelly's Cove watershed, Northport, Maine, USA. Interpretation of the data is complicated by the lack of correlations between sulfate concentrations an...

Oxygen delivery does not limit thermal tolerance in a tropical eurythermal crustacean.

PubMed

Ern, Rasmus; Huong, Do Thi Thanh; Phuong, Nguyen Thanh; Wang, Tobias; Bayley, Mark

2014-03-01

In aquatic environments, rising water temperatures reduce water oxygen content while increasing oxygen demand, leading several authors to propose cardiorespiratory oxygen transport capacity as the main determinant of aquatic animal fitness. It has also been argued that tropical species, compared with temperate species, live very close to their upper thermal limit and hence are vulnerable to even small elevations in temperature. Little, however, is known about physiological responses to high temperatures in tropical species. Here we report that the tropical giant freshwater shrimp (Macrobrachium rosenbergii) maintains normal growth when challenged by a temperature rise of 6°C above the present day average (from 27°C to 33°C). Further, by measuring heart rate, gill ventilation rate, resting and maximum oxygen uptake, and hemolymph lactate, we show that oxygen transport capacity is maintained up to the critical maximum temperature around 41°C. In M. rosenbergii heart rate and gill ventilation rate increases exponentially until immediately below critical temperatures and at 38°C animals still retained more than 76% of aerobic scope measured at 30°C, and there was no indication of anaerobic metabolism at the high temperatures. Our study shows that the oxygen transport capacity is maintained at high temperatures, and that other mechanisms, such as protein dysfunction, are responsible for the loss of ecological performance at elevated temperatures.

The cingulo-opercular network provides word-recognition benefit.

PubMed

Vaden, Kenneth I; Kuchinsky, Stefanie E; Cute, Stephanie L; Ahlstrom, Jayne B; Dubno, Judy R; Eckert, Mark A

2013-11-27

Recognizing speech in difficult listening conditions requires considerable focus of attention that is often demonstrated by elevated activity in putative attention systems, including the cingulo-opercular network. We tested the prediction that elevated cingulo-opercular activity provides word-recognition benefit on a subsequent trial. Eighteen healthy, normal-hearing adults (10 females; aged 20-38 years) performed word recognition (120 trials) in multi-talker babble at +3 and +10 dB signal-to-noise ratios during a sparse sampling functional magnetic resonance imaging (fMRI) experiment. Blood oxygen level-dependent (BOLD) contrast was elevated in the anterior cingulate cortex, anterior insula, and frontal operculum in response to poorer speech intelligibility and response errors. These brain regions exhibited significantly greater correlated activity during word recognition compared with rest, supporting the premise that word-recognition demands increased the coherence of cingulo-opercular network activity. Consistent with an adaptive control network explanation, general linear mixed model analyses demonstrated that increased magnitude and extent of cingulo-opercular network activity was significantly associated with correct word recognition on subsequent trials. These results indicate that elevated cingulo-opercular network activity is not simply a reflection of poor performance or error but also supports word recognition in difficult listening conditions.

Intermittent hypoxia activates peptidylglycine α-amidating monooxygenase in rat brain stem via reactive oxygen species-mediated proteolytic processing

PubMed Central

Sharma, Suresh D.; Raghuraman, Gayatri; Lee, Myeong-Seon; Prabhakar, Nanduri R.; Kumar, Ganesh K.

2009-01-01

Intermittent hypoxia (IH) associated with sleep apneas leads to cardiorespiratory abnormalities that may involve altered neuropeptide signaling. The effects of IH on neuropeptide synthesis have not been investigated. Peptidylglycine α-amidating monooxygenase (PAM; EC 1.14.17.3) catalyzes the α-amidation of neuropeptides, which confers biological activity to a large number of neuropeptides. PAM consists of O2-sensitive peptidylglycine α-hydroxylating monooxygenase (PHM) and peptidyl-α-hydroxyglycine α-amidating lyase (PAL) activities. Here, we examined whether IH alters neuropeptide synthesis by affecting PAM activity and, if so, by what mechanisms. Experiments were performed on the brain stem of adult male rats exposed to IH (5% O2 for 15 s followed by 21% O2 for 5 min; 8 h/day for up to 10 days) or continuous hypoxia (0.4 atm for 10 days). Analysis of brain stem extracts showed that IH, but not continuous hypoxia, increased PHM, but not PAL, activity of PAM and that the increase of PHM activity was associated with a concomitant elevation in the levels of α-amidated forms of substance P and neuropeptide Y. IH increased the relative abundance of 42- and 35-kDa forms of PHM (∼1.6- and 2.7-fold, respectively), suggesting enhanced proteolytic processing of PHM, which appears to be mediated by an IH-induced increase of endoprotease activity. Kinetic analysis showed that IH increases Vmax but has no effect on Km. IH increased generation of reactive oxygen species in the brain stem, and systemic administration of antioxidant prevented IH-evoked increases of PHM activity, proteolytic processing of PHM, endoprotease activity, and elevations in substance P and neuropeptide Y amide levels. Taken together, these results demonstrate that IH activates PHM in rat brain stem via reactive oxygen species-dependent posttranslational proteolytic processing and further suggest that PAM activation may contribute to IH-mediated peptidergic neurotransmission in rat brain stem. PMID:18818385

Intermittent hypoxia activates peptidylglycine alpha-amidating monooxygenase in rat brain stem via reactive oxygen species-mediated proteolytic processing.

PubMed

Sharma, Suresh D; Raghuraman, Gayatri; Lee, Myeong-Seon; Prabhakar, Nanduri R; Kumar, Ganesh K

2009-01-01

Intermittent hypoxia (IH) associated with sleep apneas leads to cardiorespiratory abnormalities that may involve altered neuropeptide signaling. The effects of IH on neuropeptide synthesis have not been investigated. Peptidylglycine alpha-amidating monooxygenase (PAM; EC 1.14.17.3) catalyzes the alpha-amidation of neuropeptides, which confers biological activity to a large number of neuropeptides. PAM consists of O(2)-sensitive peptidylglycine alpha-hydroxylating monooxygenase (PHM) and peptidyl-alpha-hydroxyglycine alpha-amidating lyase (PAL) activities. Here, we examined whether IH alters neuropeptide synthesis by affecting PAM activity and, if so, by what mechanisms. Experiments were performed on the brain stem of adult male rats exposed to IH (5% O(2) for 15 s followed by 21% O(2) for 5 min; 8 h/day for up to 10 days) or continuous hypoxia (0.4 atm for 10 days). Analysis of brain stem extracts showed that IH, but not continuous hypoxia, increased PHM, but not PAL, activity of PAM and that the increase of PHM activity was associated with a concomitant elevation in the levels of alpha-amidated forms of substance P and neuropeptide Y. IH increased the relative abundance of 42- and 35-kDa forms of PHM ( approximately 1.6- and 2.7-fold, respectively), suggesting enhanced proteolytic processing of PHM, which appears to be mediated by an IH-induced increase of endoprotease activity. Kinetic analysis showed that IH increases V(max) but has no effect on K(m). IH increased generation of reactive oxygen species in the brain stem, and systemic administration of antioxidant prevented IH-evoked increases of PHM activity, proteolytic processing of PHM, endoprotease activity, and elevations in substance P and neuropeptide Y amide levels. Taken together, these results demonstrate that IH activates PHM in rat brain stem via reactive oxygen species-dependent posttranslational proteolytic processing and further suggest that PAM activation may contribute to IH-mediated peptidergic neurotransmission in rat brain stem.

Net superoxide levels: steeper increase with activity in cooler female and hotter male lizards.

PubMed

Ballen, Cissy; Healey, Mo; Wilson, Mark; Tobler, Michael; Wapstra, Erik; Olsson, Mats

2012-03-01

Ectotherms increase their body temperature in response to ambient heat, thereby elevating their metabolic rate. An often inferred consequence of this is an overall upregulation of gene expression and energetic expenditure, and a concomitant increased production of reactive oxygen species (e.g. superoxide) and, perhaps, a shortened lifespan. However, recent work shows that this may be a superficial interpretation. For example, sometimes a reduced temperature may in fact trigger up-regulation of gene expression. We studied temperature and associated activity effects in male and female Australian painted dragon lizards (Ctenophorus pictus) by allowing the lizards to bask for 4 h versus 12 h, and scoring their associated activity (inactive versus active basking and foraging). As predicted, long-basking lizards (hereafter 'hot') showed heightened activity in both sexes, with a more pronounced effect in females. We then tested for sex-specific effects of basking treatment and activity levels on the increase in net levels of superoxide. In males, short-baskers (hereafter 'cold') had significantly more rapidly decreasing levels of superoxide per unit increasing activity than hot males. In females, however, superoxide levels increased faster with increasing activity in the cold than in the hot basking treatment, and females earlier in the ovarian cycle had lower superoxide levels than females closer to ovulation. In short, males and females differ in how their levels of reactive oxygen species change with temperature-triggered activity.

Cumulative mtDNA damage and mutations contribute to the progressive loss of RGCs in a rat model of glaucoma

PubMed Central

Nickerson, John M.; Gao, Feng-juan; Sun, Zhongmou; Chen, Xin-ya; Zhang, Shu-jie; Gao, Feng; Chen, Jun-yi; Luo, Yi; Wang, Yan; Sun, Xing-huai

2015-01-01

Glaucoma is a chronic neurodegenerative disease characterized by the progressive loss of retinal ganglion cells (RGCs). Mitochondrial DNA (mtDNA) alterations have been documented as a key component of many neurodegenerative disorders. However, whether mtDNA alterations contribute to the progressive loss of RGCs and the mechanism whereby this phenomenon could occur are poorly understood. We investigated mtDNA alterations in RGCs using a rat model of chronic intraocular hypertension and explored the mechanisms underlying progressive RGC loss. We demonstrate that the mtDNA damage and mutations triggered by intraocular pressure (IOP) elevation are initiating, crucial events in a cascade leading to progressive RGC loss. Damage to and mutation of mtDNA, mitochondrial dysfunction, reduced levels of mtDNA repair/replication enzymes, and elevated reactive oxygen species form a positive feedback loop that produces irreversible mtDNA damage and mutation and contributes to progressive RGC loss, which occurs even after a return to normal IOP. Furthermore, we demonstrate that mtDNA damage and mutations increase the vulnerability of RGCs to elevated IOP and glutamate levels, which are among the most common glaucoma insults. This study suggests that therapeutic approaches that target mtDNA maintenance and repair and that promote energy production may prevent the progressive death of RGCs. PMID:25478814

Aldosterone induces fibrosis, oxidative stress and DNA damage in livers of male rats independent of blood pressure changes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Queisser, Nina; Happ, Kathrin; Link, Samuel

Mineralocorticoid receptor blockers show antifibrotic potential in hepatic fibrosis. The mechanism of this protective effect is not known yet, although reactive oxygen species seem to play an important role. Here, we investigated the effects of elevated levels of aldosterone (Ald), the primary ligand of the mineralocorticoid receptor, on livers of rats in a hyperaldosteronism model: aldosterone-induced hypertension. Male Sprague–Dawley rats were treated for 4 weeks with aldosterone. To distinguish if damage caused in the liver depended on increased blood pressure or on increased Ald levels, the mineralocorticoid receptor antagonist spironolactone was given in a subtherapeutic dose, not normalizing blood pressure.more » To investigate the impact of oxidative stress, the antioxidant tempol was administered. Aldosterone induced fibrosis, detected histopathologically, and by expression analysis of the fibrosis marker, α-smooth muscle actin. Further, the mRNA amount of the profibrotic cytokine TGF-β was increased significantly. Fibrosis could be reduced by scavenging reactive oxygen species, and also by blocking the mineralocorticoid receptor. Furthermore, aldosterone treatment caused oxidative stress and DNA double strand breaks in livers, as well as the elevation of DNA repair activity. An increase of the transcription factor Nrf2, the main regulator of the antioxidative response could be observed, and of its target genes heme oxygenase-1 and γ-glutamylcysteine synthetase. All these effects of aldosterone were prevented by spironolactone and tempol. Already after 4 weeks of treatment, aldosteroneinfusion induced fibrosis in the liver. This effect was independent of elevated blood pressure. DNA damage caused by aldosterone might contribute to fibrosis progression when aldosterone is chronically increased. - Highlights: • Aldosterone has direct profibrotic effects on the liver independent of blood pressure. • Fibrosis is mediated by the mineralocorticoid receptor and oxidative stress. • Aldosterone induces transcription factor Nrf2 and Nrf2-regulated genes in the liver. • DNA damage caused by aldosterone might contribute to fibrosis progression.« less

Combined effects of constant sublethal UVA irradiation and elevated temperature on the survival and general metabolism of the convict-cichlid fish, Cichlasoma nigrofasciatum.

PubMed

Winckler, K; Fidhiany, L

1996-04-01

In a previous study we observed that a constant sublethal UVA (320-400 nm) irradiation had a significant effect on the general metabolism in the Convict-cichlid fish (Cichlasoma nigrofasciatum) [Winckler, K. and Fidhiany, L. (1996) J. Photochem. Photobiol. B. Biol. (In press)]. In the present study we show that sublethal UVA irradiation in combination with elevated environmental temperature has a deleterious effect on the same population. The threshold temperature for a sudden increase in mortality of fish receiving an additional sublethal UVA irradiation was 32 degrees C. Prior to the increased mortality, the fish started to avoid the UV light source when the water temperature increased to 31.5 degrees C. Mortality decreased when the temperature declined below 31.5 degrees C. As soon as the temperature changed to normal (adapted) condition (27-29 degrees C) mortality returned to normal levels. In contrast, no changes of fish behavior or mortality were observed at elevated temperature in the nonirradiated reference population. The percentages of fish surviving the high temperature stress were 21.9% for the UVA population and 96.8% for the reference population. The specific oxygen consumption (SOC, average +/- SD) of the survivors from the UVA population during temperature stress was 0.21 +/- 0.05 mg O2 h-1 g body weight (BW)-1, while it was 0.54 +/- 0.11 mg O2 h-1 g BW-1 in the reference population. After the environmental temperature returned below the apparent upper temperature tolerance limit, the oxygen consumption of the UVA population gradually normalized. The SOC measured at different temperature levels--after after the fish passed the temperature stress--showed no significant differences between the UVA population and its reference at 23, 25, 27 and 29 degrees C. However, the SOC at 31 degrees C was significantly (P < 0.05) lower than reference, while at 33 degrees C it was higher (P < 0.10).

Facing the river gauntlet: understanding the effects of fisheries capture and water temperature on the physiology of coho salmon.

PubMed

Raby, Graham D; Clark, Timothy D; Farrell, Anthony P; Patterson, David A; Bett, Nolan N; Wilson, Samantha M; Willmore, William G; Suski, Cory D; Hinch, Scott G; Cooke, Steven J

2015-01-01

An improved understanding of bycatch mortality can be achieved by complementing field studies with laboratory experiments that use physiological assessments. This study examined the effects of water temperature and the duration of net entanglement on physiological disturbance and recovery in coho salmon (Oncorhynchus kisutch) after release from a simulated beach seine capture. Heart rate was monitored using implanted electrocardiogram biologgers that allowed fish to swim freely before and after release. A subset of fish was recovered in respirometers to monitor metabolic recovery, and separate groups of fish were sacrificed at different times to assess blood and white muscle biochemistry. One hour after release, fish had elevated lactate in muscle and blood plasma, depleted tissue energy stores, and altered osmoregulatory status, particularly in warmer (15 vs. 10°C) and longer (15 vs. 2 min) capture treatments. A significant effect of entanglement duration on blood and muscle metabolites remained after 4 h. Oxygen consumption rate recovered to baseline within 7-10 h. However, recovery of heart rate to routine levels was longer and more variable, with most fish taking over 10 h, and 33% of fish failing to recover within 24 h. There were no significant treatment effects on either oxygen consumption or heart rate recovery. Our results indicate that fishers should minimize handling time for bycatch and maximize oxygen supply during crowding, especially when temperatures are elevated. Physiological data, such as those presented here, can be used to understand mechanisms that underlie bycatch impairment and mortality, and thus inform best practices that ensure the welfare and conservation of affected species.

Low-Dose Ethanol Preconditioning Protects Against Oxygen-Glucose Deprivation/Reoxygenation-Induced Neuronal Injury By Activating Large Conductance, Ca2+-Activated K+ Channels In Vitro.

PubMed

Su, Fang; Guo, An-Chen; Li, Wei-Wei; Zhao, Yi-Long; Qu, Zheng-Yi; Wang, Yong-Jun; Wang, Qun; Zhu, Yu-Lan

2017-02-01

Increasing evidence suggests that low to moderate ethanol ingestion protects against the deleterious effects of subsequent ischemia/reperfusion; however, the underlying mechanism has not been elucidated. In the present study, we showed that expression of the neuronal large-conductance, Ca 2+ -activated K + channel (BK Ca ) α-subunit was upregulated in cultured neurons exposed to oxygen-glucose deprivation/reoxygenation (OGD/R) compared with controls. Preconditioning with low-dose ethanol (10 mmol/L) increased cell survival rate in neurons subjected to OGD/R, attenuated the OGD/R-induced elevation of cytosolic Ca 2+ levels, and reduced the number of apoptotic neurons. Western blots revealed that ethanol preconditioning upregulated expression of the anti-apoptotic protein Bcl-2 and downregulated the pro-apoptotic protein Bax. The protective effect of ethanol preconditioning was antagonized by a BK Ca channel inhibitor, paxilline. Inside-out patches in primary neurons also demonstrated the direct activation of the BK Ca channel by 10 mmol/L ethanol. The above results indicated that low-dose ethanol preconditioning exerts its neuroprotective effects by attenuating the elevation of cytosolic Ca 2+ and preventing neuronal apoptosis, and this is mediated by BK Ca channel activation.

Role of Oxygen Free Radicals, Nitric Oxide and Mitochondria in Mediating Cardiac Alterations During Liver Cirrhosis Induced by Thioacetamide.

PubMed

Amirtharaj, G Jayakumar; Natarajan, Sathish Kumar; Pulimood, Anna; Balasubramanian, K A; Venkatraman, Aparna; Ramachandran, Anup

2017-04-01

Thioacetamide (TAA) administration is widely used for induction of liver cirrhosis in rats, where reactive oxygen radicals (ROS) and nitric oxide (NO) participate in development of liver damage. Cardiac dysfunction is an important complication of liver cirrhosis, but the role of ROS or NO in cardiac abnormalities during liver cirrhosis is not well understood. This was investigated in animals after TAA-induced liver cirrhosis and temporal changes in oxidative stress, NO and mitochondrial function in the heart evaluated. TAA induced elevation in cardiac levels of nitrate before development of frank liver cirrhosis, without gross histological alterations. This was accompanied by an early induction of P38 MAP kinase, which is influenced by ROS and plays an important signaling role for induction of iNOS. Increased nitrotyrosine, protein oxidation and lipid peroxidation in the heart and cardiac mitochondria, suggestive of oxidative stress, also preceded frank liver cirrhosis. However, compromised cardiac mitochondrial function with a decrease in respiratory control ratio and increased mitochondrial swelling was seen later, when cirrhosis was evident. In conclusion, TAA induces elevations in ROS and NO in the heart in parallel to early liver damage. This leads to later development of functional deficits in cardiac mitochondria after development of liver cirrhosis.

Reactive oxygen species, vascular Noxs, and hypertension: focus on translational and clinical research.

PubMed

Montezano, Augusto C; Touyz, Rhian M

2014-01-01

Reactive oxygen species (ROS) are signaling molecules that are important in physiological processes, including host defense, aging, and cellular homeostasis. Increased ROS bioavailability and altered redox signaling (oxidative stress) have been implicated in the onset and/or progression of chronic diseases, including hypertension. Although oxidative stress may not be the only cause of hypertension, it amplifies blood pressure elevation in the presence of other pro-hypertensive factors, such as salt loading, activation of the renin-angiotensin-aldosterone system, and sympathetic hyperactivity, at least in experimental models. A major source for ROS in the cardiovascular-renal system is a family of nicotinamide adenine dinucleotide phosphate oxidases (Noxs), including the prototypic Nox2-based Nox, and Nox family members: Nox1, Nox4, and Nox5. Although extensive experimental data support a role for increased ROS levels and altered redox signaling in the pathogenesis of hypertension, the role in clinical hypertension is unclear, as a direct causative role of ROS in blood pressure elevation has yet to be demonstrated in humans. Nevertheless, what is becoming increasingly evident is that abnormal ROS regulation and aberrant signaling through redox-sensitive pathways are important in the pathophysiological processes which is associated with vascular injury and target-organ damage in hypertension. There is a paucity of clinical information related to the mechanisms of oxidative stress and blood pressure elevation, and a few assays accurately measure ROS directly in patients. Such further ROS research is needed in humans and in the development of adequately validated analytical methods to accurately assess oxidative stress in the clinic.

Genetic predisposition to liver damage after halothane anesthesia in guinea pigs.

PubMed

Lunam, C A; Cousins, M J; Hall, P M

1986-11-01

Three 4-hr normoxic (21% oxygen) exposures to 1% halothane administered 3 days apart were associated with elevations in serum alanine aminotransferase (ALT) activity in four of 20 guinea pigs after the initial and third exposures. Serum alanine aminotransferase values were not measured after the second anesthetic. Susceptibility was defined as an ALT level greater than 300 IU/L after halothane. Nonsusceptible animals, that is, animals without significant increases in ALT values after halothane, remained nonsusceptible after reexposure. Serum alanine aminotransferase values after the first and third anesthesias were significantly correlated (rs = 0.86, P less than 0.001). Two exposures of another 30 guinea pigs at a 5-week interval resulted in high elevations of ALT in the same eight animals after both anesthetics. In contrast, after an initial exposure nonsusceptible animals remained nonsusceptible upon reexposure. Serum alanine aminotransferase levels after the first and second anesthetics were significantly correlated (rs = 0.85, P less than 0.001). The proportion of first generation (F1) males with elevated ALTs whose parents were susceptible to halothane hepatotoxicity (HH) was significantly higher than the proportion of males with elevated ALTs in a random group of 90 males (P less than 0.005). First generation males and females of nonsusceptible parents had ALTs within the normal range after halothane exposure. These studies suggest that in the guinea pig genetic predisposition is an important determinant of susceptibility to HH, although other contributing factors are not excluded.

On the role of radiation and dimensionality in predicting flow opposed flame spread over thin fuels

NASA Astrophysics Data System (ADS)

Kumar, Chenthil; Kumar, Amit

2012-06-01

In this work a flame-spread model is formulated in three dimensions to simulate opposed flow flame spread over thin solid fuels. The flame-spread model is coupled to a three-dimensional gas radiation model. The experiments [1] on downward spread and zero gravity quiescent spread over finite width thin fuel are simulated by flame-spread models in both two and three dimensions to assess the role of radiation and effect of dimensionality on the prediction of the flame-spread phenomena. It is observed that while radiation plays only a minor role in normal gravity downward spread, in zero gravity quiescent spread surface radiation loss holds the key to correct prediction of low oxygen flame spread rate and quenching limit. The present three-dimensional simulations show that even in zero gravity gas radiation affects flame spread rate only moderately (as much as 20% at 100% oxygen) as the heat feedback effect exceeds the radiation loss effect only moderately. However, the two-dimensional model with the gas radiation model badly over-predicts the zero gravity flame spread rate due to under estimation of gas radiation loss to the ambient surrounding. The two-dimensional model was also found to be inadequate for predicting the zero gravity flame attributes, like the flame length and the flame width, correctly. The need for a three-dimensional model was found to be indispensable for consistently describing the zero gravity flame-spread experiments [1] (including flame spread rate and flame size) especially at high oxygen levels (>30%). On the other hand it was observed that for the normal gravity downward flame spread for oxygen levels up to 60%, the two-dimensional model was sufficient to predict flame spread rate and flame size reasonably well. Gas radiation is seen to increase the three-dimensional effect especially at elevated oxygen levels (>30% for zero gravity and >60% for normal gravity flames).

Effects of natural and human-induced hypoxia on coastal benthos

NASA Astrophysics Data System (ADS)

Levin, L. A.; Ekau, W.; Gooday, A. J.; Jorissen, F.; Middelburg, J. J.; Naqvi, W.; Neira, C.; Rabalais, N. N.; Zhang, J.

2009-04-01

Coastal hypoxia (<1.42 ml L-1; 62.5 μM; 2 mg L-1, approx. 30% oxygen saturation) occurs seasonally in many estuaries, fjords, and along open coasts subject to upwelling or excessive riverine nutrient input, and permanently in some isolated seas and marine basins. Underlying causes of hypoxia include enhanced nutrient input from natural causes (upwelling) or anthropogenic origin (eutrophication) and reduction of mixing by limited circulation or enhanced stratification; combined these lead to higher surface water production, microbial respiration and eventual oxygen depletion. Advective inputs of low-oxygen waters may initiate or expand hypoxic conditions. Responses of estuarine, enclosed sea, and open shelf benthos to hypoxia depend on the duration, predictability, and intensity of oxygen depletion and on whether H2S is formed. Under suboxic conditions, large mats of filamentous sulfide oxidizing bacteria cover the seabed and consume sulfide, thereby providing a detoxified microhabitat for eukaryotic benthic communities. Calcareous foraminiferans and nematodes are particularly tolerant of low oxygen concentrations and may attain high densities and dominance, often in association with microbial mats. When oxygen is sufficient to support metazoans, small, soft-bodied invertebrates (typically annelids), often with short generation times and elaborate branchial structures, predominate. Large taxa are more sensitive than small taxa to hypoxia. Crustaceans and echinoderms are typically more sensitive to hypoxia, with lower oxygen thresholds, than annelids, sipunculans, molluscs and cnidarians. Mobile fish and shellfish will migrate away from low-oxygen areas. Within a species, early life stages may be more subject to oxygen stress than older life stages. Hypoxia alters both the structure and function of benthic communities, but effects may differ with regional hypoxia history. Human-caused hypoxia is generally linked to eutrophication, and occurs adjacent to watersheds with large populations or agricultural activities. Many occurrences are seasonal, within estuaries, fjords or enclosed seas of the North Atlantic and the NW Pacific Oceans. Benthic faunal responses, elicited at oxygen levels below 2 ml L-1, typically involve avoidance or mortality of large species and elevated abundances of enrichment opportunists, sometimes prior to population crashes. Areas of low oxygen persist seasonally or continuously beneath upwelling regions, associated with the upper parts of oxygen minimum zones (SE Pacific, W Africa, N Indian Ocean). These have a distribution largely distinct from eutrophic areas and support a resident fauna that is adapted to survive and reproduce at oxygen concentrations <0.5 ml L-1. Under both natural and eutrophication-caused hypoxia there is loss of diversity, through attrition of intolerant species and elevated dominance, as well as reductions in body size. These shifts in species composition and diversity yield altered trophic structure, energy flow pathways, and corresponding ecosystem services such as production, organic matter cycling and organic C burial. Increasingly the influences of nature and humans interact to generate or exacerbate hypoxia. A warmer ocean is more stratified, holds less oxygen, and may experience greater advection of oxygen-poor source waters, making new regions subject to hypoxia. Future understanding of benthic responses to hypoxia must be established in the context of global climate change and other human influences such as overfishing, pollution, disease, habitat loss, and species invasions.

Oxygen Consumption and Usage During Physical Exercise: The Balance Between Oxidative Stress and ROS-Dependent Adaptive Signaling

PubMed Central

Zhao, Zhongfu; Koltai, Erika; Ohno, Hideki; Atalay, Mustafa

2013-01-01

Abstract The complexity of human DNA has been affected by aerobic metabolism, including endurance exercise and oxygen toxicity. Aerobic endurance exercise could play an important role in the evolution of Homo sapiens, and oxygen was not important just for survival, but it was crucial to redox-mediated adaptation. The metabolic challenge during physical exercise results in an elevated generation of reactive oxygen species (ROS) that are important modulators of muscle contraction, antioxidant protection, and oxidative damage repair, which at moderate levels generate physiological responses. Several factors of mitochondrial biogenesis, such as peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α), mitogen-activated protein kinase, and SIRT1, are modulated by exercise-associated changes in the redox milieu. PGC-1α activation could result in decreased oxidative challenge, either by upregulation of antioxidant enzymes and/or by an increased number of mitochondria that allows lower levels of respiratory activity for the same degree of ATP generation. Endogenous thiol antioxidants glutathione and thioredoxin are modulated with high oxygen consumption and ROS generation during physical exercise, controlling cellular function through redox-sensitive signaling and protein–protein interactions. Endurance exercise-related angiogenesis, up to a significant degree, is regulated by ROS-mediated activation of hypoxia-inducible factor 1α. Moreover, the exercise-associated ROS production could be important to DNA methylation and post-translation modifications of histone residues, which create heritable adaptive conditions based on epigenetic features of chromosomes. Accumulating data indicate that exercise with moderate intensity has systemic and complex health-promoting effects, which undoubtedly involve regulation of redox homeostasis and signaling. Antioxid. Redox Signal. 18, 1208–1246. PMID:22978553

Climate-dependent evolution of Antarctic ectotherms: An integrative analysis

NASA Astrophysics Data System (ADS)

Pörtner, Hans O.

2006-04-01

The paper explores the climate-dependent evolution of marine Antarctic fauna and tries to identify key mechanisms involved as well as the driving forces that have caused the physiological and life history characteristics observed today. In an integrative approach it uses the recent concept of oxygen and capacity limited thermal tolerance to identify potential links between molecular, cellular, whole-organism, and ecological characteristics of marine animal life in the Antarctic. As a generalized pattern, minimization of baseline energy costs, for the sake of maximized growth in the cold, appears as one over-arching principle shaping the evolution and functioning of Antarctic marine ectotherms. This conclusion is supported by recent comparisons with (sub-) Arctic ectotherms, where elevated levels of energy turnover result at unstable, including cold temperatures, and are related to wide windows of thermal tolerance and associated metabolic features. At biochemical levels, metabolic regulation at low temperatures in general, is supported by the cold compensation of enzyme kinetic parameters like substrate affinities and turnover numbers, through minute structural modifications of the enzyme molecule. These involve a shift in protein folding, sometimes supported by the replacement of individual amino acids. The hypothesis is developed that efficient metabolic regulation at low rates in Antarctic marine stenotherms occurs through high mitochondrial densities at low capacities and possibly enhanced levels of Arrhenius activation energies or activation enthalpies. This contrasts the more costly patterns of metabolic regulation at elevated rates in cold-adapted eurytherms. Energy savings in Antarctic ectotherms, largely exemplified in fish, typically involve low-cost, diffusive oxygen distribution due to high density of lipid membranes, loss of haemoglobin, myoglobin and the heat shock response, reduced anaerobic capacity, large myocytes with low ion exchange activities, and the use of lipid body stores for neutral buoyancy. Important trade-offs result from obligatory energy savings in the permanent cold: low metabolic rates support cold-compensated growth but imply narrow windows of thermal tolerance and reduced scopes for activity. The degree of thermal specialization is not uniformly defined by cold temperature but varies with life style characteristics and activity levels and associated aerobic scope. Trade-offs for the sake of cold compensated growth parallel reduced capacities for exercise performance, exacerbated by the effect of high haemolymph magnesium levels in crustaceans and, possibly, other invertebrates. High magnesium levels likely exclude the group of reptant decapod crustaceans from Antarctic waters below 0 °C. The hypothesis is developed that energy savings imposed by the permanent cold bear specific life history consequences. Due to effects of allometry, energy savings are exacerbated at small body size, favouring passive lecithotrophic larvae. At all stages of life history, reduced energy turnover for the sake of growth causes delays and low rates in other higher functions, with the result of late maturity, fecundity and offspring release, as well as extended development. As a consequence, extended life spans evolved due to life history requirements. At the same time, polar gigantism is enabled by a combination of elevated oxygen levels in cold waters, of reduced metabolism and of extended periods of growth at slow developmental rates.

Remote sensing of stress using electro-optics imaging technique

NASA Astrophysics Data System (ADS)

Chen, Tong; Yuen, Peter; Hong, Kan; Tsitiridis, Aristeidis; Kam, Firmin; Jackman, James; James, David; Richardson, Mark; Oxford, William; Piper, Jonathan; Thomas, Francis; Lightman, Stafford

2009-09-01

Emotional or physical stresses induce a surge of adrenaline in the blood stream under the command of the sympathetic nerve system, which, cannot be suppressed by training. The onset of this alleviated level of adrenaline triggers a number of physiological chain reactions in the body, such as dilation of pupil and an increased feed of blood to muscles etc. This paper reports for the first time how Electro-Optics (EO) technologies such as hyperspectral [1,2] and thermal imaging[3] methods can be used for the detection of stress remotely. Preliminary result using hyperspectral imaging technique has shown a positive identification of stress through an elevation of haemoglobin oxygenation saturation level in the facial region, and the effect is seen more prominently for the physical stressor than the emotional one. However, all results presented so far in this work have been interpreted together with the base line information as the reference point, and that really has limited the overall usefulness of the developing technology. The present result has highlighted this drawback and it prompts for the need of a quantitative assessment of the oxygenation saturation and to correlate it directly with the stress level as the top priority of the next stage of research.

Ammonium excretion and oxygen respiration of tropical copepods and euphausiids exposed to oxygen minimum zone conditions

NASA Astrophysics Data System (ADS)

Kiko, Rainer; Hauss, Helena; Buchholz, Friedrich; Melzner, Frank

2016-04-01

Calanoid copepods and euphausiids are key components of marine zooplankton communities worldwide. Most euphausiids and several copepod species perform diel vertical migrations (DVMs) that contribute to the export of particulate and dissolved matter to midwater depths. In vast areas of the global ocean, and in particular in the eastern tropical Atlantic and Pacific, the daytime distribution depth of many migrating organisms corresponds to the core of the oxygen minimum zone (OMZ). At depth, the animals experience reduced temperature and oxygen partial pressure (pO2) and an increased carbon dioxide partial pressure (pCO2) compared to their near-surface nighttime habitat. Although it is well known that low oxygen levels can inhibit respiratory activity, the respiration response of tropical copepods and euphausiids to relevant pCO2, pO2, and temperature conditions remains poorly parameterized. Further, the regulation of ammonium excretion at OMZ conditions is generally not well understood. It was recently estimated that DVM-mediated ammonium supply could fuel bacterial anaerobic ammonium oxidation - a major loss process for fixed nitrogen in the ocean considerably. These estimates were based on the implicit assumption that hypoxia or anoxia in combination with hypercapnia (elevated pCO2) does not result in a down-regulation of ammonium excretion. We exposed calanoid copepods from the Eastern Tropical North Atlantic (ETNA; Undinula vulgaris and Pleuromamma abdominalis) and euphausiids from the Eastern Tropical South Pacific (ETSP; Euphausia mucronata) and the ETNA (Euphausia gibboides) to different temperatures, carbon dioxide and oxygen levels to study their survival, respiration and excretion rates at these conditions. An increase in temperature by 10 °C led to an approximately 2-fold increase of the respiration and excretion rates of U. vulgaris (Q10, respiration = 1.4; Q10, NH4-excretion = 1.6), P. abdominalis (Q10, respiration = 2.0; Q10, NH4-excretion = 2.4) and E. gibboides (Q10, respiration = 2.0; Q10, NH4-excretion = 2.4; E. mucronata not tested). Exposure to differing carbon dioxide levels had no overall significant impact on the respiration or excretion rates. Species from the ETNA were less tolerant to low oxygen levels than E. mucronata from the ETSP, which survived exposure to anoxia at 13 °C. Respiration and excretion rates were reduced upon exposure to low oxygen levels, albeit at different species-specific levels. Reduction of the excretion and respiration rates in ETNA species occurred at a pO2 of 0.6 (P. abdominalis) and 2.4 kPa (U. vulgaris and E. gibboides) at OMZ temperatures. Such low oxygen levels are normally not encountered by these species in the ETNA. E. mucronata however regularly migrates into the strongly hypoxic to anoxic core of the ETSP OMZ. Exposure to low oxygen levels led to a strong reduction of respiration and ammonium excretion in E. mucronata (pcrit respiration = 0.6, pcrit NH4-excretion = 0.73). A drastic reduction of respiratory activity was also observed by other authors for euphausiids, squat lobsters and calanoid copepods, but was not yet accounted for when calculating DVM-mediated active fluxes into the ETSP OMZ. Current estimates of DVM-mediated active export of carbon and nitrogen into the ETSP OMZ are therefore likely too high and future efforts to calculate these export rates should take the physiological responses of migratory species to OMZ conditions into account.

Integration of the Second Messenger c-di-GMP into the Chemotactic Signaling Pathway

PubMed Central

Russell, Matthew H.; Bible, Amber N.; Fang, Xin; Gooding, Jessica R.; Campagna, Shawn R.; Gomelsky, Mark; Alexandre, Gladys

2013-01-01

ABSTRACT Elevated intracellular levels of the bacterial second messenger c-di-GMP are known to suppress motility and promote sessility. Bacterial chemotaxis guides motile cells in gradients of attractants and repellents over broad concentration ranges, thus allowing bacteria to quickly adapt to changes in their surroundings. Here, we describe a chemotaxis receptor that enhances, as opposed to suppresses, motility in response to temporary increases in intracellular c-di-GMP. Azospirillum brasilense’s preferred metabolism is adapted to microaerophily, and these motile cells quickly navigate to zones of low oxygen concentration by aerotaxis. We observed that changes in oxygen concentration result in rapid changes in intracellular c-di-GMP levels. The aerotaxis and chemotaxis receptor, Tlp1, binds c-di-GMP via its C-terminal PilZ domain and promotes persistent motility by increasing swimming velocity and decreasing swimming reversal frequency, which helps A. brasilense reach low-oxygen zones. If c-di-GMP levels remain high for extended periods, A. brasilense forms nonmotile clumps or biofilms on abiotic surfaces. These results suggest that association of increased c-di-GMP levels with sessility is correct on a long-term scale, while in the short-term c-di-GMP may actually promote, as opposed to suppress, motility. Our data suggest that sensing c-di-GMP by Tlp1 functions similar to methylation-based adaptation. Numerous chemotaxis receptors contain C-terminal PilZ domains or other sensory domains, suggesting that intracellular c-di-GMP as well as additional stimuli can be used to modulate adaptation of bacterial chemotaxis receptors. PMID:23512960

Drought effects on water quality in the South Platte River Basin, Colorado

USGS Publications Warehouse

Sprague, Lori A.

2005-01-01

Twenty-three stream sites representing a range of forested, agricultural, and urban land uses were sampled in the South Platte River Basin of Colorado from July through September 2002 to characterize water quality during drought conditions. With a few exceptions, dissolved ammonia, Kjeldahl nitrogen, total phosphorus, and dissolved orthophosphate concentrations were similar to seasonal historical levels in all land use areas during the drought. At some agricultural sites, decreased dilution of irrigation return flow may have contributed to higher concentrations of some nutrient species, increased primary productivity, and higher dissolved oxygen concentrations. At some urban sites, decreased dilution of base flow and wastewater treatment plant effluent may have contributed to higher dissolved nitrite-plus-nitrate concentrations, increased primary productivity, and higher dissolved oxygen concentrations. Total pesticide concentrations in urban and agricultural areas were not consistently higher or lower during the drought. At most forested sites, decreased dilution of ground water-derived calcium bicarbonate type base flow likely led to elevated pH and specific-conductance values. Water temperatures at many of the forested sites also were higher, contributing to lower dissolved oxygen concentrations during the drought.

Coal/Biomass-to-Liquids Demonstration Testing for DLA Energy: Report on Project Tests, Evaluations, and Recommendations

DTIC Science & Technology

2015-08-20

elevated temperatures with sub- stoichiometric oxygen to produce primarily hydrogen and carbon monoxide (called syngas). Syngas can be used for the...of the gasifier and flows downward concurrently with nitrogen, pure oxygen , and steam. The EFG operates at very high temperatures (nominal 2,700... temperature slagging gasifiers), these components are cracked and thermally converted to product gas, especially in the presence of steam and oxygen . For

Mechanisms Underlying Endothelin-1 Level Elevations Caused by Excessive Fluoride Exposure.

PubMed

Sun, Liyan; Gao, Yanhui; Zhang, Wei; Liu, Xiaona; Li, Bingyun; Cui, Xiaohui; Sun, Dianjun

2016-01-01

To explore the mechanisms underlying endothelin-1 (ET-1) elevations induced by excessive fluoride exposure. We measured serum and bone fluoride ion content and plasma ET-1 levels and compared these parameters among different groups in an animal model. We also observed morphological changes in the aorta and endothelium of rabbits. In cell experiments, human umbilical vein endothelial cells (HUVECs) were treated with varying concentrations of NaF for 24h, with or without 10 µM U0126 pretreatment for 1 h. ET-1 levels in culture fluid and intracellular reactive oxygen species (ROS) levels, as well as ET1 gene, endothelin-converting enzyme-1 (ECE-1), extracellular signal-regulating kinase 1/2 (ERK1/2), pERK1/2 expression levels and RAS activation were measured and compared among the groups. Plasma ET-1 levels of rabbits increased significantly in fluorinated groups compared with those in the control group. The rabbit thoracic aortas became slightly hardened in fluorinated groups compared with those in the control group, and some vacuoles were present in the endothelial cell cytoplasm of the rabbits in fluorinated groups. In our cell experiments, ET1 gene and ECE-1 expression levels in HUVECs and ET-1 expression levels in the cell culture supernatants increased significantly in some experimental groups compared with those in the control group. These trends paralleled the changes in intracellular ROS levels, RAS activation, and the pERK1/2-to-ERK1/2 ratio. After U0126 was added, ECE-1 expression and ET-1 levels decreased significantly. Excessive fluoride exposure leads to characteristic endothelial damage (vacuoles), thoracic aorta hardening, and plasma ET-1 level elevations in rabbits. In addition, the ROS-RAS-MEK1/2-pERK1/2/ERK1/2 pathway plays a crucial-and at least partial-role in ET-1 over-expression, which is promoted by excessive fluoride exposure. © 2016 The Author(s) Published by S. Karger AG, Basel.

Influence of In Vitro and In Vivo Oxygen Modulation on β Cell Differentiation From Human Embryonic Stem Cells

PubMed Central

Cechin, Sirlene; Álvarez-Cubela, Silvia; Giraldo, Jaime A.; Molano, Ruth D.; Villate, Susana; Ricordi, Camillo; Pileggi, Antonello; Inverardi, Luca

2014-01-01

The possibility of using human embryonic stem (hES) cell-derived β cells as an alternative to cadaveric islets for the treatment of type 1 diabetes is now widely acknowledged. However, current differentiation methods consistently fail to generate meaningful numbers of mature, functional β cells. In order to address this issue, we set out to explore the role of oxygen modulation in the maturation of pancreatic progenitor (PP) cells differentiated from hES cells. We have previously determined that oxygenation is a powerful driver of murine PP differentiation along the endocrine lineage of the pancreas. We hypothesized that targeting physiological oxygen partial pressure (pO2) levels seen in mature islets would help the differentiation of PP cells along the β-cell lineage. This hypothesis was tested both in vivo (by exposing PP-transplanted immunodeficient mice to a daily hyperbaric oxygen regimen) and in vitro (by allowing PP cells to mature in a perfluorocarbon-based culture device designed to carefully adjust pO2 to a desired range). Our results show that oxygen modulation does indeed contribute to enhanced maturation of PP cells, as evidenced by improved engraftment, segregation of α and β cells, body weight maintenance, and rate of diabetes reversal in vivo, and by elevated expression of pancreatic endocrine makers, β-cell differentiation yield, and insulin production in vitro. Our studies confirm the importance of oxygen modulation as a key variable to consider in the design of β-cell differentiation protocols and open the door to future strategies for the transplantation of fully mature β cells. PMID:24375542

A Physiological Signature of the Cost of Reproduction Associated with Parental Care.

PubMed

Fowler, Melinda A; Williams, Tony D

2017-12-01

Costs of reproduction are an integral and long-standing component of life-history theory, but we still know relatively little about the specific physiological mechanisms underlying these trade-offs. We experimentally manipulated workload during parental care in female European starlings (Sturnus vulgaris) using attachment of radios and/or wing clipping and assessed measures of workload, current breeding productivity, future fecundity, and survival (local return rate) in relation to treatment. Females with wing clipping and radio attachment paid a clear cost of reproduction compared with all other treatment groups: they had lower future fecundity and lower return rates despite having lower current breeding productivity. We then measured 13 physiological traits, including measures of aerobic/metabolic capacity, oxidative stress and muscle damage, intermediary metabolism and energy supply, and immune function. Our results show that the cost of reproduction in females with wing clipping and radio attachment was associated with lower oxygen-carrying capacity (lower hematocrit and hemoglobin levels), lower energy reserves (plasma nonesterified fatty acid and triglyceride levels), decreased immune function (lower haptoglobin levels), and elevated levels of oxidative stress (higher levels of dROMs [reactive oxygen metabolites] and lower levels of the endogenous antioxidant uric acid). Our study provides evidence that costs of reproduction involve a widespread decline in physiological function across multiple physiological systems consistent with long-standing ideas of cumulative "wear and tear" and allostatic load.

Cenozoic topographic and climatic response to changing tectonic boundary conditions in Western North America

NASA Astrophysics Data System (ADS)

Kent-Corson, Malinda L.; Sherman, Laura S.; Mulch, Andreas; Chamberlain, C. Page

2006-12-01

This study presents an oxygen isotopic record from the Paleocene to the Pliocene based on the analysis of predominantly paleosol carbonate from intermontane basins in southwestern Montana and eastern Idaho. δ18O values of calcite decrease by 7 to 10‰ between ˜ 50 and 47 Ma in southwestern Montana and Idaho most likely as a result of an increase in elevation of 2.5 to 3.5 km. This rise in elevation is roughly contemporaneous with the emplacement of the nearby Challis Volcanics, and the formation of metamorphic core complexes in the hinterland of the Sevier thrust belt. Moreover, when compared to previous oxygen isotopic studies that show oxygen isotopic shifts of similar magnitude occurring later (in the late Eocene to early Oligocene in northeastern Nevada, and late Oligocene to Miocene in southern Nevada), the results of this study add to a growing body of evidence for a spatial and temporal migration of high surface elevations from north to south in the Great Basin of western United States. This surface uplift history supports tectonic models calling for north to south removal of the Farallon slab or delamination of the mantle lithosphere.

Algogenic substances and metabolic status in work-related Trapezius Myalgia: a multivariate explorative study.

PubMed

Gerdle, Björn; Kristiansen, Jesper; Larsson, Britt; Saltin, Bengt; Søgaard, Karen; Sjøgaard, Gisela

2014-10-28

This study compares the levels of algesic substances between subjects with trapezius myalgia (TM) and healthy controls (CON) and explores the multivariate correlation pattern between these substances, pain, and metabolic status together with relative blood flow changes reported in our previous paper (Eur J Appl Physiol 108:657-669, 2010). 43 female workers with (TM) and 19 females without (CON) trapezius myalgia were - using microdialysis - compared for differences in interstitial concentrations of interleukin-6 (IL-6), bradykinin (BKN), serotonin (5-HT), lactate dehydrogenas (LDH), substance P, and N-terminal propeptide of procollagen type I (PINP) in the trapezius muscle at rest and during repetitive/stressful work. These data were also used in multivariate analyses together with previously presented data (Eur J Appl Physiol 108:657-669, 2010): trapezius muscle blood flow, metabolite accumulation, oxygenation, and pain development and sensitivity. Substance P was significantly elevated in TM (p=0.0068). No significant differences were found in the classical algesic substances (p: 0.432-0.926). The multivariate analysis showed that blood flow related variables, interstitial concentrations of metabolic (pyruvate), and algesic (BKN and K+) substances were important for the discrimination of the subjects to one of the two groups (R2: 0.19-0.31, p<0.05). Pain intensity was positively associated with levels of 5-HT and K+ and negatively associated with oxygenation indicators and IL-6 in TM (R2: 0.24, p<0.05). A negative correlation existed in TM between mechanical pain sensitivity of trapezius and BKN and IL-6 (R2: 0.26-0.39, p<0.05). The present study increased understanding alterations in the myalgic muscle. When considering the system-wide aspects, increased concentrations of lactate, pyruvate and K+ and decreased oxygenation characterized TM compared to CON. There are three major possible explanations for this finding: the workers with pain had relatively low severity of myalgia, metabolic alterations preceded detectable alterations in levels of algesics, or peripheral sensitization and other muscle alterations existed in TM. Only SP of the investigated algesic substances was elevated in TM. Several of the algesics were of importance for the levels of pain intensity and mechanical pain sensitivity in TM. These results indicate peripheral contribution to maintenance of central nociceptive and pain mechanisms and may be important to consider when designing treatments.

Bartter/Gitelman syndromes as a model to study systemic oxidative stress in humans.

PubMed

Maiolino, Giuseppe; Azzolini, Matteo; Rossi, Gian Paolo; Davis, Paul A; Calò, Lorenzo A

2015-11-01

Reactive oxygen species (ROS) are intermediates in reduction-oxidation reactions that begin with the addition of one electron to molecular oxygen, generating the primary ROS superoxide, which in turn interacts with other molecules to produce secondary ROS, such as hydrogen peroxide, hydroxyl radical, and peroxynitrite. ROS are continuously produced during metabolic processes and are deemed to play an important role in cardiovascular diseases, namely, myocardial hypertrophy and fibrosis and atherosclerosis, via oxidative damage of lipids, proteins, and deoxyribonucleic acid. Angiotensin II (Ang II) is a potent vasoactive agent that also exerts mitogenic, proinflammatory, and profibrotic effects through several signaling pathways, in part involving ROS, particularly superoxide and hydrogen peroxide. Moreover, Ang II stimulates NADPH oxidases, leading to higher ROS generation and oxidative stress. Bartter/Gitelman syndrome patients, despite elevated plasma renin activity, Ang II, and aldosterone levels, exhibit reduced peripheral resistance, normal/low blood pressure, and blunted pressor effect of vasoconstrictors. In addition, notwithstanding the activation of the renin-angiotensin system and the increased plasma levels of Ang II, these patients display decreased production of ROS, reduced oxidative stress, and increased antioxidant defenses. In fact, Bartter/Gitelman syndrome patients are characterized by reduced levels of p22(phox) gene expression and undetectable plasma peroxynitrite levels, while showing increased plasma antioxidant power and expression of antioxidant enzymes, such as heme oxygenase-1. In conclusion, multifarious data suggest that Bartter and Gitelman syndrome patients are a model of low oxidative stress and high antioxidant defenses. The contribution offered by the study of these syndromes in elucidating the molecular mechanisms underlying this favorable status could offer chances for new therapeutic targets in disease characterized by high levels of reactive oxygen species. Copyright © 2015 Elsevier Inc. All rights reserved.

Preterm birth and oxidative stress: Effects of acute physical exercise and hypoxia physiological responses.

PubMed

Martin, Agnès; Faes, Camille; Debevec, Tadej; Rytz, Chantal; Millet, Grégoire; Pialoux, Vincent

2018-05-01

Preterm birth is a global health issue that can induce lifelong medical sequela. Presently, at least one in ten newborns are born prematurely. At birth, preterm newborns exhibit higher levels of oxidative stress (OS) due to the inability to face the oxygen rich environment in which they are born into. Moreover, their immature respiratory, digestive, immune and antioxidant defense systems, as well as the potential numerous medical interventions following a preterm birth, such as oxygen resuscitation, nutrition, phototherapy and blood transfusion further contribute to high levels of OS. Although the acute effects seem well established, little is known regarding the long-term effects of preterm birth on OS. This matter is especially important given that chronically elevated OS levels may persist into adulthood and consequently contribute to the development of numerous non-communicable diseases observed in people born preterm such as diabetes, hypertension or lung disorders. The purpose of this review is to summarize the current knowledge regarding the consequences of preterm birth on OS levels from newborn to adulthood. In addition, the effects of physical activity and hypoxia, both known to disrupt redox balance, on OS modulation in preterm individuals are also explored. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

Impaired Muscle Oxygenation and Elevated Exercise Blood Pressure in Hypertensive Patients: Links With Vascular Stiffness.

PubMed

Dipla, Konstantina; Triantafyllou, Areti; Koletsos, Nikolaos; Papadopoulos, Stavros; Sachpekidis, Vasileios; Vrabas, Ioannis S; Gkaliagkousi, Eugenia; Zafeiridis, Andreas; Douma, Stella

2017-08-01

This study examined in vivo (1) skeletal muscle oxygenation and microvascular function, at rest and during handgrip exercise, and (2) their association with macrovascular function and exercise blood pressure (BP), in newly diagnosed, never-treated patients with hypertension and normotensive individuals. Ninety-one individuals (51 hypertensives and 40 normotensives) underwent office and 24-hour ambulatory BP, arterial stiffness, and central aortic BP assessment, followed by a 5-minute arterial occlusion and a 3-minute submaximal handgrip exercise. Changes in muscle oxygenated and deoxygenated hemoglobin and tissue oxygen saturation were continuously monitored by near-infrared spectroscopy and beat-by-beat BP by Finapres. Hypertensives had higher ( P <0.001) central aortic BP and pulse wave velocity versus normotensives and exhibited (1) a blunted tissue oxygen saturation response during occlusion, with slower ( P =0.006) deoxygenation rate, suggesting reduced muscle oxidative capacity, and (2) a slower reoxygenation rate and blunted hyperemic response ( P <0.05), showing reduced microvascular reactivity. Muscle oxygenation responses were correlated with aortic systolic and pulse pressure and augmentation index ( P <0.05; age and body mass index (BMI) adjusted). When exercising at the same submaximal intensity, hypertensives required a significantly greater ( P <0.001) increase in BP for achieving similar muscle oxygenation levels as normotensives. This response was correlated with the magnitude of microvascular hyperemia and aortic BP. In conclusion, nontreated patients with hypertension exhibit prominent reductions in in vivo indices of skeletal muscle oxidative capacity, suggestive of mitochondrial dysfunction, and blunted muscle microvascular reactivity. These dysfunctions were associated with higher aortic systolic BP and arterial stiffness. Dysregulations in muscle oxygen delivery/utilization and microvascular stiffness, in hypertensive patients, partially contribute to their exaggerated BP during exercise. © 2017 American Heart Association, Inc.

Modified atmosphere packaging of fruits and vegetables.

PubMed

Kader, A A; Zagory, D; Kerbel, E L

1989-01-01

Modified atmospheres (MA), i.e., elevated concentrations of carbon dioxide and reduced levels of oxygen and ethylene, can be useful supplements to provide optimum temperature and relative humidity in maintaining the quality of fresh fruits and vegetables after harvest. MA benefits include reduced respiration, ethylene production, and sensitivity to ethylene; retarded softening and compositional changes; alleviation of certain physiological disorders; and reduced decay. Subjecting fresh produce to too low an oxygen concentration and/or to too high a carbon dioxide level can result in MA stress, which is manifested by accelerated deterioration. Packaging fresh produce in polymeric films can result in a commodity-generated MA. Atmosphere modification within such packages depends on film permeability, commodity respiration rate and gas diffusion characteristics, and initial free volume and atmospheric composition within the package. Temperature, relative humidity, and air movement around the package can influence the permeability of the film. Temperature also affects the metabolic activity of the commodity and consequently the rate of attaining the desired MA. All these factors must be considered in developing a mathematical model for selecting the most suitable film for each commodity.

Tamoxifen dosing for Cre-mediated recombination in experimental bronchopulmonary dysplasia.

PubMed

Ruiz-Camp, Jordi; Rodríguez-Castillo, José Alberto; Herold, Susanne; Mayer, Konstantin; Vadász, István; Tallquist, Michelle D; Seeger, Werner; Ahlbrecht, Katrin; Morty, Rory E

2017-02-01

Bronchopulmonary dysplasia (BPD) is the most common complication of preterm birth characterized by blunted post-natal lung development. BPD can be modelled in mice by exposure of newborn mouse pups to elevated oxygen levels. Little is known about the mechanisms of perturbed lung development associated with BPD. The advent of transgenic mice, where genetic rearrangements can be induced in particular cell-types at particular time-points during organogenesis, have great potential to explore the pathogenic mechanisms at play during arrested lung development. Many inducible, conditional transgenic technologies available rely on the application of the estrogen-receptor modulator, tamoxifen. While tamoxifen is well-tolerated and has been widely employed in adult mice, or in healthy developing mice; tamoxifen is not well-tolerated in combination with hyperoxia, in the most widely-used mouse model of BPD. To address this, we set out to establish a safe and effective tamoxifen dosing regimen that can be used in newborn mouse pups subjected to injurious stimuli, such as exposure to elevated levels of environmental oxygen. Our data reveal that a single intraperitoneal dose of tamoxifen of 0.2 mg applied to newborn mouse pups in 10 μl Miglyol vehicle was adequate to successfully drive Cre recombinase-mediated genome rearrangements by the fifth day of life, in a murine model of BPD. The number of recombined cells was comparable to that observed in regular tamoxifen administration protocols. These findings will be useful to investigators where tamoxifen dosing is problematic in the background of injurious stimuli and mouse models of human and veterinary disease.

Cell Wall Invertase Promotes Fruit Set under Heat Stress by Suppressing ROS-Independent Cell Death1[OPEN

PubMed Central

2016-01-01

Reduced cell wall invertase (CWIN) activity has been shown to be associated with poor seed and fruit set under abiotic stress. Here, we examined whether genetically increasing native CWIN activity would sustain fruit set under long-term moderate heat stress (LMHS), an important factor limiting crop production, by using transgenic tomato (Solanum lycopersicum) with its CWIN inhibitor gene silenced and focusing on ovaries and fruits at 2 d before and after pollination, respectively. We found that the increase of CWIN activity suppressed LMHS-induced programmed cell death in fruits. Surprisingly, measurement of the contents of H2O2 and malondialdehyde and the activities of a cohort of antioxidant enzymes revealed that the CWIN-mediated inhibition on programmed cell death is exerted in a reactive oxygen species-independent manner. Elevation of CWIN activity sustained Suc import into fruits and increased activities of hexokinase and fructokinase in the ovaries in response to LMHS. Compared to the wild type, the CWIN-elevated transgenic plants exhibited higher transcript levels of heat shock protein genes Hsp90 and Hsp100 in ovaries and HspII17.6 in fruits under LMHS, which corresponded to a lower transcript level of a negative auxin responsive factor IAA9 but a higher expression of the auxin biosynthesis gene ToFZY6 in fruits at 2 d after pollination. Collectively, the data indicate that CWIN enhances fruit set under LMHS through suppression of programmed cell death in a reactive oxygen species-independent manner that could involve enhanced Suc import and catabolism, HSP expression, and auxin response and biosynthesis. PMID:27462084

Low-Dissolved-Oxygen Nitrifying Systems Exploit Ammonia-Oxidizing Bacteria with Unusually High Yields▿

PubMed Central

Bellucci, Micol; Ofiţeru, Irina D.; Graham, David W.; Head, Ian M.; Curtis, Thomas P.

2011-01-01

In wastewater treatment plants, nitrifying systems are usually operated with elevated levels of aeration to avoid nitrification failures. This approach contributes significantly to operational costs and the carbon footprint of nitrifying wastewater treatment processes. In this study, we tested the effect of aeration rate on nitrification by correlating ammonia oxidation rates with the structure of the ammonia-oxidizing bacterial (AOB) community and AOB abundance in four parallel continuous-flow reactors operated for 43 days. Two of the reactors were supplied with a constant airflow rate of 0.1 liter/min, while in the other two units the airflow rate was fixed at 4 liters/min. Complete nitrification was achieved in all configurations, though the dissolved oxygen (DO) concentration was only 0.5 ± 0.3 mg/liter in the low-aeration units. The data suggest that efficient performance in the low-DO units resulted from elevated AOB levels in the reactors and/or putative development of a mixotrophic AOB community. Denaturing gel electrophoresis and cloning of AOB 16S rRNA gene fragments followed by sequencing revealed that the AOB community in the low-DO systems was a subset of the community in the high-DO systems. However, in both configurations the dominant species belonged to the Nitrosomonas oligotropha lineage. Overall, the results demonstrated that complete nitrification can be achieved at low aeration in lab-scale reactors. If these findings could be extended to full-scale plants, it would be possible to minimize the operational costs and greenhouse gas emissions without risk of nitrification failure. PMID:21926211

Low NO[sub x], cogeneration process and system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bell, R.D.

1993-07-06

A process is described for low NO[sub x] cogeneration to produce electricity and useful heat, which comprises: providing fuel and oxygen to an internal combustion engine connected to drive an electric generator, to thereby generate electricity; recovering from said engine an exhaust stream including elevated NO[sub x] levels and combined oxygen; adding to said exhaust stream sufficient fuel to create a fuel-rich mixture, the quantity of fuel being sufficient to react with the available oxygen and reduce the NO[sub x], in said exhaust stream; providing said fuel-enriched exhaust stream to a thermal reactor and reacting therein said fuel, NO[sub x]more » and available oxygen, to provide a heated oxygen-depleted stream; cooling said oxygen-depleted stream by passing same through a first heat exchanger; adding conversion oxygen to said cooled stream from said heat exchanger, and passing the cooled oxygen-augmented stream over a first catalyst bed operated at a temperature of about 750 to 1,250 F under overall reducing conditions, the quantity of conversion oxygen added being in stoichiometric excess of the amount of NO[sub x], but less than the amount of combustibles; whereby the NO[sub x] is first oxidized to NO[sub 2], and then the NO[sub 2] is reduced by the excess combustibles; cooling said stream from said first catalyst bed to a temperature of about 450 to 650 F by passing said stream through a second heat exchanger; adding air to the resulting cooled stream to produce a further cooled stream at a temperature of about 400 to 600 F, and having a stoichiometric excess of oxygen; and passing said stream having said stoichiometric excess of oxygen over an oxidizing catalyst bed at said temperature of 400 to 600 F to oxidize remaining excess combustibles, to thereby provide an effluent stream having environmentally safe characteristics.« less

Low Oxygen and Ocean Acidification on the Vancouver Island Shelf

NASA Astrophysics Data System (ADS)

Bianucci, L.; Denman, K.

2008-12-01

In the recent years hypoxic events have been observed along the west coast of North America (off Oregon and California). Although a common cause of coastal hypoxia is usually anthropogenic eutrophication, in these upwelling regions the advection of oxygen-depleted waters from offshore is a key mechanism. Moreover, the high productivity typical of these margins generates a large flux of sinking particular organic matter. The remineralization of this matter below the euphotic zone produces an elevated consumption of oxygen. When concentrations become lower than certain threshold, hypoxia leads to a major change in the ecosystem and the affected areas are called 'dead zones'. Furthermore, the two processes that drive oxygen levels down (physical upwelling and biological demand) also increase dissolved inorganic carbon in the shelf, which leads to a pH reduction. Ocean acidification and hypoxia can severely affect ecosystems, and the links between these phenomena have not been explored. This presentation will discuss a model study of the carbon and oxygen coupling on the Vancouver Island shelf, with focus on the connection between acidification and hypoxia. Moreover, the role of biology versus physics will be investigated. This region comprises the northern end of the wind-driven upwelling margin off western North America, where low oxygen events have not been extensively studied. However, the proximity to an Oxygen Minimum Zone offshore and the observed decline of oxygen in the Northeast Pacific turns this shelf into a potential candidate to suffer from low-oxygen events. The model used is the Regional Ocean Modeling System (ROMS) in a quasi-2D configuration of the shelf (across-shore section with uniform properties alongshore). The biogeochemical model has carbon, oxygen, and nitrogen as state variables, and includes cycling of dissolved organic matter. Carbon and oxygen cycles are coupled through ecosystem processes such as photosynthesis and remineralization, while they are decoupled by other processes (e.g., nitrification and denitrification).

Reduced Autophagy in 5-Fluorouracil Resistant Colon Cancer Cells

PubMed Central

Yao, Cheng Wen; Kang, Kyoung Ah; Piao, Mei Jing; Ryu, Yea Seong; Fernando, Pattage Madushan Dilhara Jayatissa; Oh, Min Chang; Park, Jeong Eon; Shilnikova, Kristina; Na, Soo-Young; Jeong, Seung Uk; Boo, Sun-Jin; Hyun, Jin Won

2017-01-01

We investigated the role of autophagy in SNUC5/5-FUR, 5-fluorouracil (5-FU) resistant SNUC5 colon cancer cells. SNUC5/5-FUR cells exhibited low level of autophagy, as determined by light microscopy, confocal microscopy, and flow cytometry following acridine orange staining, and the decreased level of GFP-LC3 puncta. In addition, expression of critical autophagic proteins such as Atg5, Beclin-1 and LC3-II and autophagic flux was diminished in SNUC5/5-FUR cells. Whereas production of reactive oxygen species (ROS) was significantly elevated in SNUC5/5-FUR cells, treatment with the ROS inhibitor N-acetyl cysteine further reduced the level of autophagy. Taken together, these results indicate that decreased autophagy is linked to 5-FU resistance in SNUC5 colon cancer cells. PMID:27737524

Markers of Oxidative Stress and Neuroprogression in Depression Disorder

PubMed Central

Vaváková, Magdaléna; Trebatická, Jana

2015-01-01

Major depression is multifactorial disorder with high prevalence and alarming prognostic in the nearest 15 years. Several mechanisms of depression are known. Neurotransmitters imbalance and imbalance between neuroprogressive and neuroprotective factors are observed in major depression. Depression is accompanied by inflammatory responses of the organism and consequent elevation of proinflammatory cytokines and increased lipid peroxidation are described in literature. Neuropsychiatric disorders including major depression are also associated with telomerase shortening, oxidative changes in nucleotides, and polymorphisms in several genes connected to metabolism of reactive oxygen species. Mitochondrion dysfunction is directly associated with increasing levels of oxidative stress. Oxidative stress plays significant role in pathophysiology of major depression via actions of free radicals, nonradical molecules, and reactive oxygen and nitrogen species. Products of oxidative stress represent important parameters for measuring and predicting of depression status as well as for determining effectiveness of administrated antidepressants. Positive effect of micronutrients, vitamins, and antioxidants in depression treatment is also reviewed. PMID:26078821

Increased Interleukin-23 in Hashimoto's Thyroiditis Disease Induces Autophagy Suppression and Reactive Oxygen Species Accumulation.

PubMed

Zheng, Tingting; Xu, Chengcheng; Mao, Chaoming; Mou, Xiao; Wu, Fei; Wang, Xuefeng; Bu, Ling; Zhou, Yuepeng; Luo, Xuan; Lu, Qingyan; Liu, Hongli; Yuan, Guoyue; Wang, Shengjun; Chen, Deyu; Xiao, Yichuan

2018-01-01

Hashimoto's thyroiditis (HT) represents the most common organ-specific autoimmune disease. Inflammatory factors and reactive oxygen species (ROS) play detrimental roles during the pathogenesis of HT. In this study, we found that thyroid follicular cells (TFCs) from HT patients expressed an elevated level of interleukin-23 (IL-23), which contributed to autophagy suppression and ROS accumulation. Additionally, IL-23-induced autophagy suppression and ROS accumulation in human TFCs was attributed to AKT/mTOR/NF-κB signaling pathway activation. Inhibition of either IL-23 by a specific neutralization antibody, or mTOR by rapamycin, or NF-κB by IKK-16, significantly reversed the autophagy suppression and ROS accumulation. These results demonstrate a key role for IL-23 in HT pathogenesis and provide a potential therapeutic strategy against IL-23 or its signaling pathway in HT.

Increased Interleukin-23 in Hashimoto’s Thyroiditis Disease Induces Autophagy Suppression and Reactive Oxygen Species Accumulation

PubMed Central

Zheng, Tingting; Xu, Chengcheng; Mao, Chaoming; Mou, Xiao; Wu, Fei; Wang, Xuefeng; Bu, Ling; Zhou, Yuepeng; Luo, Xuan; Lu, Qingyan; Liu, Hongli; Yuan, Guoyue; Wang, Shengjun; Chen, Deyu; Xiao, Yichuan

2018-01-01

Hashimoto’s thyroiditis (HT) represents the most common organ-specific autoimmune disease. Inflammatory factors and reactive oxygen species (ROS) play detrimental roles during the pathogenesis of HT. In this study, we found that thyroid follicular cells (TFCs) from HT patients expressed an elevated level of interleukin-23 (IL-23), which contributed to autophagy suppression and ROS accumulation. Additionally, IL-23-induced autophagy suppression and ROS accumulation in human TFCs was attributed to AKT/mTOR/NF-κB signaling pathway activation. Inhibition of either IL-23 by a specific neutralization antibody, or mTOR by rapamycin, or NF-κB by IKK-16, significantly reversed the autophagy suppression and ROS accumulation. These results demonstrate a key role for IL-23 in HT pathogenesis and provide a potential therapeutic strategy against IL-23 or its signaling pathway in HT. PMID:29434604

Stabilization of Oxidized Copper Nanoclusters in Confined Spaces

DOE PAGES

Akter, Nusnin; Wang, Mengen; Zhong, Jian-Qiang; ...

2018-01-04

Copper is an important industrial catalyst. The ability to manipulate the oxidation state of copper clusters in a controlled way is critical to understanding structure–reactivity relations of copper catalysts at the molecular level. Experimentally, cupric oxide surfaces or even small domains can only be stabilized at elevated temperatures and in the presence of oxygen, as copper can be easily reduced under reaction conditions. Herein bilayer silica films grown on a metallic substrate are used to trap diluted copper oxide clusters. By combining in situ experiments with first principles calculations, it is found that the confined space created by the silicamore » film leads to an increase in the energy barrier for Cu diffusion. Dispersed copper atoms trapped by the silica film can be easily oxidized by surface oxygen chemisorbed on the metallic substrate, which results in the formation and stabilization of Cu 2+ cations.« less

Oxygen Uptake Responses to Submaximal Exercise Loads Do Not Change During Long-Duration Space Flight

NASA Technical Reports Server (NTRS)

Moore, Alan D., Jr.; Evetts, Simon N.; Feiveson, Alan H.; Lee, S. M. C.; McCleary, Frank A.; Platts, Steven H.; Ploutz-Snyder, Lori

2011-01-01

In previous publications we have reported that the heart rate (HR) responses to graded submaximal exercise tests are elevated during long-duration International Space Station (ISS) flights. Furthermore, the elevation in HR appears greater earlier, rather than later, during the missions. A potential confounder in the interpretation of HR results from graded exercise tests on ISS is that the cycle ergometer used (CEVIS) is vibration-isolated from the station structure. This feature causes the CEVIS assembly to sway slightly during its use and debriefing comments by some crewmembers indicate that there is a "learning curve" associated with CEVIS use. Therefore, one could not exclude the possibility that the elevated HRs experienced in the early stages of ISS missions were related to a lowered metabolic efficiency of CEVIS exercise that would raise the submaximal oxygen uptake (VO2) associated with graded exercise testing work rates.

Oxygen isotopes suggest elevated thermometabolism within multiple Permo-Triassic therapsid clades

PubMed Central

Rey, Kévin; Amiot, Romain; Fourel, François; Abdala, Fernando; Fluteau, Frédéric; Jalil, Nour-Eddine; Liu, Jun; Rubidge, Bruce S; Smith, Roger MH; Steyer, J Sébastien; Viglietti, Pia A; Wang, Xu; Lécuyer, Christophe

2017-01-01

The only true living endothermic vertebrates are birds and mammals, which produce and regulate their internal temperature quite independently from their surroundings. For mammal ancestors, anatomical clues suggest that endothermy originated during the Permian or Triassic. Here we investigate the origin of mammalian thermoregulation by analysing apatite stable oxygen isotope compositions (δ18Op) of some of their Permo-Triassic therapsid relatives. Comparing of the δ18Op values of therapsid bone and tooth apatites to those of co-existing non-therapsid tetrapods, demonstrates different body temperatures and thermoregulatory strategies. It is proposed that cynodonts and dicynodonts independently acquired constant elevated thermometabolism, respectively within the Eucynodontia and Lystrosauridae + Kannemeyeriiformes clades. We conclude that mammalian endothermy originated in the Epicynodontia during the middle-late Permian. Major global climatic and environmental fluctuations were the most likely selective pressures on the success of such elevated thermometabolism. DOI: http://dx.doi.org/10.7554/eLife.28589.001 PMID:28716184

Insight into the grain boundary effect on the ionic transport of yttria-stabilized zirconia at elevated temperatures from a molecular modeling perspective

NASA Astrophysics Data System (ADS)

Chang, Kai-Shiun; Lin, Yi-Feng; Tung, Kuo-Lun

A molecular dynamics (MD) simulation is used to reveal the grain boundary effect on the ionic transport of yttria-stabilized zirconia (YSZ). The oxygen ion displacements and diffusivities of the ideal and grain boundary-inserted YSZ models are analyzed at elevated temperatures. An optimized Y 2O 3 concentration within YSZ for the best ionic conductivity is achieved by balancing the trade-off between the increased vacancies and the decreased accessible free space. The mass transfer resistance of the grain boundary in YSZ can be more easily found at higher temperatures by observing the oxygen ion diffusivities or traveling trajectories. At lower temperatures, the grain interior and the grain boundary control the ionic transport. In contrast, the grain boundary effect on the diffusion barrier is gradually eliminated at elevated temperatures. The modeled results in this work agree well with previous experimental data.

Optical imaging characterizing brain response to thermal insult in injured rodent

NASA Astrophysics Data System (ADS)

Abookasis, David; Shaul, Oren; Meitav, Omri; Pinhasi, Gadi A.

2018-02-01

We used spatially modulated optical imaging system to assess the effect of temperature elevation on intact brain tissue in a mouse heatstress model. Heatstress or heatstroke is a medical emergency defined by abnormally elevated body temperature that causes biochemical, physiological and hematological changes. During experiments, brain temperature was measured concurrently with a thermal camera while core body temperature was monitored with rectal thermocouple probe. Changes in a battery of macroscopic brain physiological parameters, such as hemoglobin oxygen saturation level, cerebral water content, as well as intrinsic tissue optical properties were monitored during temperature elevation. These concurrent changes reflect the pathophysiology of the brain during heatstress and demonstrate successful monitoring of thermoregulation mechanisms. In addition, the variation of tissue refractive index was calculated showing a monotonous decrease with increasing wavelength. We found increased temperature to greatly affect both the scattering properties and refractive index which represent cellular and subcellular swelling indicative of neuronal damage. The overall trends detected in brain tissue parameters were consistent with previous observations using conventional medical devices and optical modalities.

Proteins altered by elevated levels of palmitate or glucose implicated in impaired glucose-stimulated insulin secretion

PubMed Central

Sol, E-ri M; Hovsepyan, Meri; Bergsten, Peter

2009-01-01

Background Development of type 2 diabetes mellitus (T2DM) is characterized by aberrant insulin secretory patterns, where elevated insulin levels at non-stimulatory basal conditions and reduced hormonal levels at stimulatory conditions are major components. To delineate mechanisms responsible for these alterations we cultured INS-1E cells for 48 hours at 20 mM glucose in absence or presence of 0.5 mM palmitate, when stimulatory secretion of insulin was reduced or basal secretion was elevated, respectively. Results After culture, cells were protein profiled by SELDI-TOF-MS and 2D-PAGE. Differentially expressed proteins were discovered and identified by peptide mass fingerprinting. Complimentary protein profiles were obtained by the two approaches with SELDI-TOF-MS being more efficient in separating proteins in the low molecular range and 2D-PAGE in the high molecular range. Identified proteins included alpha glucosidase, calmodulin, gars, glucose-6-phosphate dehydrogenase, heterogenous nuclear ribonucleoprotein A3, lon peptidase, nicotineamide adenine dinucleotide hydrogen (NADH) dehydrogenase, phosphoglycerate kinase, proteasome p45, rab2, pyruvate kinase and t-complex protein. The observed glucose-induced differential protein expression pattern indicates enhanced glucose metabolism, defense against reactive oxygen species, enhanced protein translation, folding and degradation and decreased insulin granular formation and trafficking. Palmitate-induced changes could be related to altered exocytosis. Conclusion The identified altered proteins indicate mechanism important for altered β-cell function in T2DM. PMID:19607692

Influence of acute progressive hypoxia on cardiovascular variability in conscious spontaneously hypertensive rats

PubMed Central

Sugimura, Mitsutaka; Hirose, Yohsuke; Hanamoto, Hiroshi; Okada, Kenji; Boku, Aiji; Morimoto, Yoshinari; Taki, Kunitaka; Niwa, Hitoshi

2008-01-01

The purpose of this study is to examine the influence of acute progressive hypoxia on cardiovascular variability and striatal dopamine (DA) levels in conscious, spontaneously hypertensive rats (SHR) and Wistar Kyoto rats (WKY). After preparation for measurement, the inspired oxygen concentration of rats was decreased to 10% within 5 min (descent stage), maintained at 10% for 10 min (fixed stage), and then elevated back to 20% over 5 min (recovery stage). The systolic blood pressure (SBP) and heart rate (HR) variability at each stage was calculated to evaluate the autonomic nervous system response using the wavelet method. Striatal DA during each stage was measured using in vivo microdialysis. We found that SHR showed a more profound hemodynamic response to progressive hypoxia as compared to WKY. Cardiac parasympathetic activity in SHR was significantly inhibited by acute progressive hypoxia during all stages, as shown by the decrease in the high frequency band of HR variability (HR-HF), along with transient increase in sympathetic activity during the early hypoxic phase. This decrease in the HR-HF continued even when SBP was elevated. Striatal DA levels showed the transient similar elevation in both groups. These findings suggest that acute progressive hypoxic stress in SHR inhibits cardiac parasympathetic activity through reduction of baroreceptor reflex sensitivity, with potentially severe deleterious effects on circulation, in particular on HR and circulatory control. Furthermore, it is thought that the influence of acute progressive hypoxia on striatal DA levels is similar in SHR and WKY. PMID:18599365

Elevated Serum Hepcidin Levels during an Intensified Training Period in Well-Trained Female Long-Distance Runners

PubMed Central

Ishibashi, Aya; Maeda, Naho; Sumi, Daichi; Goto, Kazushige

2017-01-01

Iron is essential for providing oxygen to working muscles during exercise, and iron deficiency leads to decreased exercise capacity during endurance events. However, the mechanism of iron deficiency among endurance athletes remains unclear. In this study, we compared iron status between two periods involving different training regimens. Sixteen female long-distance runners participated. Over a seven-month period, fasting blood samples were collected during their regular training period (LOW; middle of February) and during an intensified training period (INT; late of August) to determine blood hematological, iron, and inflammatory parameters. Three-day food diaries were also assessed. Body weight and lean body mass did not differ significantly between LOW and INT, while body fat and body fat percentage were significantly lower in INT (p < 0.05). Blood hemoglobin, serum ferritin, total protein, and iron levels, total iron-binding capacity, and transferrin saturation did not differ significantly between the two periods. Serum hepcidin levels were significantly higher during INT than LOW (p < 0.05). Carbohydrate and iron intakes from the daily diet were significantly higher during INT than LOW (p < 0.05). In conclusion, an elevated hepcidin level was observed during an intensified training period in long-distance runners, despite an apparently adequate daily intake of iron. PMID:28335426

Elevated Serum Hepcidin Levels during an Intensified Training Period in Well-Trained Female Long-Distance Runners.

PubMed

Ishibashi, Aya; Maeda, Naho; Sumi, Daichi; Goto, Kazushige

2017-03-14

Iron is essential for providing oxygen to working muscles during exercise, and iron deficiency leads to decreased exercise capacity during endurance events. However, the mechanism of iron deficiency among endurance athletes remains unclear. In this study, we compared iron status between two periods involving different training regimens. Sixteen female long-distance runners participated. Over a seven-month period, fasting blood samples were collected during their regular training period (LOW; middle of February) and during an intensified training period (INT; late of August) to determine blood hematological, iron, and inflammatory parameters. Three-day food diaries were also assessed. Body weight and lean body mass did not differ significantly between LOW and INT, while body fat and body fat percentage were significantly lower in INT ( p < 0.05). Blood hemoglobin, serum ferritin, total protein, and iron levels, total iron-binding capacity, and transferrin saturation did not differ significantly between the two periods. Serum hepcidin levels were significantly higher during INT than LOW ( p < 0.05). Carbohydrate and iron intakes from the daily diet were significantly higher during INT than LOW ( p < 0.05). In conclusion, an elevated hepcidin level was observed during an intensified training period in long-distance runners, despite an apparently adequate daily intake of iron.

Optically stimulated luminescence age controls on late Pleistocene and Holocene coastal lithosomes, North Carolina, USA

USGS Publications Warehouse

Mallinson, D.; Burdette, K.; Mahan, S.; Brook, G.

2008-01-01

Luminescence ages from a variety of coastal features on the North Carolina Coastal Plain provide age control for shoreline formation and relative sea-level position during the late Pleistocene. A series of paleoshoreline ridges, dating to Marine Isotope Stage (MIS) 5a and MIS 3 have been defined. The Kitty Hawk beach ridges, on the modern Outer Banks, yield ages of 3 to 2??ka. Oxygen-isotope data are used to place these deposits in the context of global climate and sea-level change. The occurrence of MIS 5a and MIS 3 shorelines suggests that glacio-isostatic adjustment (GIA) of the study area is large (ca. 22 to 26??m), as suggested and modeled by other workers, and/or MIS 3 sea level was briefly higher than suggested by some coral reef studies. Correcting the shoreline elevations for GIA brings their elevation in line with other sea-level indicators. The age of the Kitty Hawk beach ridges places the Holocene shoreline well west of its present location at ca. 3 to 2??ka. The age of shoreline progradation is consistent with the ages of other beach ridge complexes in the southeast USA, suggesting some regionally contemporaneous forcing mechanism. ?? 2007 University of Washington.

Expression of Aleutian Low variations by a proxy record of precipitation oxygen isotopes in the Matanuska-Susitna region on Cook Inlet, south central Alaska

NASA Astrophysics Data System (ADS)

Finney, B.; Anderson, L.; Engstrom, D. R.

2017-12-01

North Pacific ocean-atmosphere processes strongly influence the climatology of Alaska by altering the strength and position of the Aleutian Low. During the past decade, the development of oxygen isotope proxy records that reflect the isotope composition of precipitation has provided substantial evidence of hydroclimatic variability in Alaska in response to Aleutian Low variations during the Holocene. However, a clear understanding of how the isotopic composition of precipitation reflects Aleutian Low variations remains uncertain because modern and proxy observations and modeling studies provide different predictions for regions (coastal and interior), elevations (0 to 5000 m), and time-scales (seasonal to century) that cannot be adequately tested by existing data. Precipitation isotope proxy records from Mount Logan, Denali, Jellybean Lake and Horse Trail Fen provide valuable perspectives at high elevation and interior (leeward) locations but no data has been available from near sea level on the coastal (windward) side of the Alaska and Chugach Mountain Ranges. Here we present newly recovered marl lake sediment cores from the Matanuska-Susitna region of Knik Arm on Cook Inlet, near Wasilla, 50 km north of Anchorage, AK that provide complete de-glacial and Holocene records of precipitation oxygen isotopes. Geochronology is underway based on identification of known tephras and AMS radiocarbon dating of terrestrial macrofossils. Modern and historic sediments are dated by 210Pb. The groundwater fed site is hydrologically open, unaffected by evaporation, has exceptionally high rates of marl sedimentation and preliminary results indicate clearly defined oxygen isotope excursions in the late 1970's and early 1940's, periods when North Pacific ocean-atmosphere forcing of the Aleutian Low is known to have undergone shifts. These results help to evaluate contrasting models of atmospheric circulation and associated isotope fractionation which is critical for proxy interpretation of paleo-records.

[The results of combined ozone therapy using in complex treatment of soft tissues infections in patients with diabetes mellitus type II].

PubMed

Vinnik, Iu S; Salmina, A B; Tepliakova, O V; Drobushevskaia, A I; Pozhilenkova, E A; Morgun, A V; Shapran, M V; Kovalenko, A O

2015-01-01

Levels of interleukins-6, 8, 10, TNF-alpha and basic fibroblast growth factor (bFGF) were examined in peripheral blood of 60 patients with diabetes mellitus type II and soft tissues infections. It was revealed the elevated levels of proinflammatory (IL-6, 8), anti-inflammatory (IL-10) cytokines and basic fibroblast growth factor at the time of admission. Application of combined ozone therapy including ozonated autohemotherapy and superficial management of wounds with ozone-oxygen mixture resulted in significant decrease of IL-6, 8, 10 production and high level of bFGF on blood serum. Thus effective local bactericidal impact of ozone in combination with normalization of proinflammatory cytokines levels and preserved high level of bFGF in peripheral blood provide better results of wound healing process in patients with diabetes mellitus type II.

Effect of Rhizobium and arbuscular mycorrhizal fungi inoculation on electrolyte leakage in Phaseolus vulgaris roots overexpressing RbohB.

PubMed

Arthikala, Manoj-Kumar; Nava, Noreide; Quinto, Carmen

2015-01-01

Respiratory oxidative burst homolog (RBOH)-mediated reactive oxygen species (ROS) regulate a wide range of biological functions in plants. They play a critical role in the symbiosis between legumes and nitrogen-fixing bacteria or arbuscular mycorrhizal (AM) fungi. For instance, overexpression of PvRbohB enhances nodule numbers, but reduces mycorrhizal colonization in Phaseolus vulgaris hairy roots and downregulation has the opposite effect. In the present study, we assessed the effect of both rhizobia and AM fungi on electrolyte leakage in transgenic P. vulgaris roots overexpressing (OE) PvRbohB. We demonstrate that elevated levels of electrolyte leakage in uninoculated PvRbohB-OE transgenic roots were alleviated by either Rhizobium or AM fungi symbiosis, with the latter interaction having the greater effect. These results suggest that symbiont colonization reduces ROS elevated electrolyte leakage in P. vulgaris root cells.

Polycythemia vera.

PubMed

Stuart, Brian J; Viera, Anthony J

2004-05-01

Polycythemia vera is a chronic myeloproliferative disorder characterized by increased red blood cell mass. The resultant hyperviscosity of the blood predisposes such patients to thrombosis. Polycythemia vera should be suspected in patients with elevated hemoglobin or hematocrit levels, splenomegaly, or portal venous thrombosis. Secondary causes of increased red blood cell mass (e.g., heavy smoking, chronic pulmonary disease, renal disease) are more common than polycythemia vera and must be excluded. Diagnosis is made using criteria developed by the Polycythemia Vera Study Group; major criteria include elevated red blood cell mass, normal oxygen saturation, and palpable splenomegaly. Untreated patients may survive for six to 18 months, whereas adequate treatment may extend life expectancy to more than 10 years. Treatment includes phlebotomy with the possible addition of myelosuppressive agents based on a risk-stratified approach. Agents under investigation include interferon alfa-2b, anagrelide, and aspirin. Consultation with a hematologist is recommended.

Concepts in hypoxia reborn

PubMed Central

2010-01-01

The human fetus develops in a profoundly hypoxic environment. Thus, the foundations of our physiology are built in the most hypoxic conditions that we are ever likely to experience: the womb. This magnitude of exposure to hypoxia in utero is rarely experienced in adult life, with few exceptions, including severe pathophysiology in critical illness and environmental hypobaric hypoxia at high altitude. Indeed, the lowest recorded levels of arterial oxygen in adult humans are similar to those of a fetus and were recorded just below the highest attainable elevation on the Earth's surface: the summit of Mount Everest. We propose that the hypoxic intrauterine environment exerts a profound effect on human tolerance to hypoxia. Cellular mechanisms that facilitate fetal well-being may be amenable to manipulation in adults to promote survival advantage in severe hypoxemic stress. Many of these mechanisms act to modify the process of oxygen consumption rather than oxygen delivery in order to maintain adequate tissue oxygenation. The successful activation of such processes may provide a new chapter in the clinical management of hypoxemia. Thus, strategies employed to endure the relative hypoxia in utero may provide insights for the management of severe hypoxemia in adult life and ventures to high altitude may yield clues to the means by which to investigate those strategies. PMID:20727228

Elevated pentraxin 3 level at the early stage of exercise training is associated with reduction of arterial stiffness in middle-aged and older adults.

PubMed

Zempo-Miyaki, A; Fujie, S; Sato, K; Hasegawa, N; Sanada, K; Maeda, S; Hamaoka, T; Iemitsu, M

2016-09-01

Regular exercise improves aging-induced deterioration of arterial stiffness, and is associated with elevated production of pentraxin 3 (PTX3) and anti-inflammatory as well as anti-atherosclerotic effects. However, the time-dependent effect of exercise training on arterial stiffness and PTX3 production remains unclear. The purpose of this study was to investigate the time course of the association between the effects of training on the circulating PTX3 level and arterial stiffness in middle-aged and older adults. Thirty-two healthy Japanese subjects (66.2±1.3 year) were randomly divided into two groups: training (exercise intervention) and sedentary controls. Subjects in the training group completed 8 weeks of aerobic exercise training (60-70% peak oxygen uptake (VO2peak) for 45 min, 3 days per week); during the training period, we evaluated plasma PTX3 concentration and carotid-femoral pulse wave velocity (cfPWV) every 2 wk. cfPWV gradually declined over the 8-week training period, and was significantly reduced after 6 and 8 week of exercise intervention (P<0.05). Plasma PTX3 level was significantly increased after 4 weeks of the intervention (P<0.05). In addition, the exercise training-induced reduction in cfPWV was negatively correlated with the percent change in plasma PTX3 level after 6 week (r=-0.54, P<0.05) and 8 weeks (r=-0.51, P<0.05) of the intervention, but not correlated at 4 weeks. Plasma PTX3 level was elevated at the early stage of the exercise training intervention, and was subsequently associated with training-induced alteration of arterial stiffness in middle-aged and older adults.

Mitigation of acrylamide-induced behavioral deficits, oxidative impairments and neurotoxicity by oral supplements of geraniol (a monoterpene) in a rat model.

PubMed

Prasad, Sathya N; Muralidhara

2014-11-05

In the recent past, several phytoconstituents are being explored for their potential neuromodulatory effects in neurological diseases. Repeated exposure of acrylamide (ACR) leads to varying degree of neuronal damage in experimental animals and humans. In view of this, the present study investigated the efficacy of geraniol (GE, a natural monoterpene) to mitigate acrylamide (ACR)-induced oxidative stress, mitochondrial dysfunction and neurotoxicity in a rat model and compared its efficacy to that of curcumin (CU, a spice active principle with multiple biological activities). ACR administration (50mg/kg bw, i.p. 3times/week) for 4weeks to growing rats caused typical symptoms of neuropathy. ACR rats provided with daily oral supplements of phytoconstituents (GE: 100mg/kg bw/d; CU: 50mg/kg bw/d, 4weeks) exhibited marked improvement in behavioral tests. Both phytoconstituents markedly attenuated ACR-induced oxidative stress as evidenced by the diminished levels of reactive oxygen species, malondialdehyde and nitric oxide and restored the reduced glutathione levels in sciatic nerve (SN) and brain regions (cortex - Ct, cerebellum - Cb). Further, both phytoconstituents effectively diminished ACR-induced elevation in cytosolic calcium levels in SN and Cb. Furthermore, diminution in the levels of oxidative markers in the mitochondria was associated with elevation in the activities of antioxidant enzymes. While ACR mediated elevation in the acetylcholinesterase activity was reduced by both actives, the depletion in dopamine levels was restored only by CU in brain regions. Taken together our findings for the first time demonstrate that the neuromodulatory propensity of GE is indeed comparable to that of CU and may be exploited as a therapeutic adjuvant in the management of varied human neuropathy conditions. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

110K Bi-Sr-Ca-Cu-O superconductor oxide and method for making same

DOEpatents

Veal, B.W.; Downey, J.W.; Lam, D.J.; Paulikas, A.P.

1992-12-22

A superconductor is disclosed consisting of a sufficiently pure phase of the oxides of Bi, Sr, Ca, and Cu to exhibit a resistive zero near 110K resulting from the process of forming a mixture of Bi[sub 2]O[sub 3], SrCO[sub 3], CaCO[sub 3] and CuO into a particulate compact wherein the atom ratios are Bi[sub 2], Sr[sub 1.2-2.2], Ca[sub 1.8-2.4], Cu[sub 3]. Thereafter, heating the particulate compact rapidly in the presence of oxygen to an elevated temperature near the melting point of the oxides to form a sintered compact, and then maintaining the sintered compact at the elevated temperature for a prolonged period of time. The sintered compact is cooled and reground. Thereafter, the reground particulate material is compacted and heated in the presence of oxygen to an elevated temperature near the melting point of the oxide and maintained at the elevated temperature for a time sufficient to provide a sufficiently pure phase to exhibit a resistive zero near 110K. 7 figs.

110K Bi-Sr-Ca-Cu-O superconductor oxide and method for making same

DOEpatents

Veal, Boyd W.; Downey, John W.; Lam, Daniel J.; Paulikas, Arvydas P.

1992-01-01

A superconductor consisting of a sufficiently pure phase of the oxides of Bi, Sr, Ca, and Cu to exhibit a resistive zero near 110K resulting from the process of forming a mixture of Bi.sub.2 O.sub.3, SrCO.sub.3, CaCO.sub.3 and CuO into aparticulate compact wherein the atom ratios are Bi.sub.2, Sr.sub.1.2-2.2, Ca.sub.1.8-2.4, Cu.sub.3. Thereafter, heating the particulate compact rapidly in the presence of oxygen to an elevated temperature near the melting point of the oxides to form a sintered compact, and then maintaining the sintered compact at the elevated temperature for a prolonged period of time. The sintered compact is cooled and reground. Thereafter, the reground particulate material is compacted and heated in the presence of oxygen to an elevated temperature near the melting point of the oxide and maintained at the elevated temperature for a time sufficient to provide a sufficiently pure phase to exhibit a resistive zero near 110K.

The Biogeographic Pattern of Microbial Functional Genes along an Altitudinal Gradient of the Tibetan Pasture

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qi, Qi; Zhao, Mengxin; Wang, Shiping

As the highest place of the world, the Tibetan plateau is a fragile ecosystem. Given the importance of microbial communities in driving soil nutrient cycling, it is of interest to document the microbial biogeographic pattern here. We adopted a microarray-based tool named GeoChip 4.0 to investigate grassland microbial functional genes along an elevation gradient from 3200 to 3800 m above sea level open to free grazing by local herdsmen and wild animals. Interestingly, microbial functional diversities increase with elevation, so does the relative abundances of genes associated with carbon degradation, nitrogen cycling, methane production, cold shock and oxygen limitation. Themore » range of Shannon diversities (10.27–10.58) showed considerably smaller variation than what was previously observed at ungrazed sites nearby (9.95–10.65), suggesting the important role of livestock grazing on microbial diversities. Closer examination showed that the dissimilarity of microbial community at our study sites increased with elevations, revealing an elevation-decay relationship of microbial functional genes. Both microbial functional diversity and the number of unique genes increased with elevations. Furthermore, we detected a tight linkage of greenhouse gas (CO2) and relative abundances of carbon cycling genes. Our biogeographic study provides insights on microbial functional diversity and soil biogeochemical cycling in Tibetan pastures.« less

A product of its environment: the epaulette shark (Hemiscyllium ocellatum) exhibits physiological tolerance to elevated environmental CO2

PubMed Central

Heinrich, Dennis D. U.; Rummer, Jodie L.; Morash, Andrea J.; Watson, Sue-Ann; Simpfendorfer, Colin A.; Heupel, Michelle R.; Munday, Philip L.

2014-01-01

Ocean acidification, resulting from increasing anthropogenic CO2 emissions, is predicted to affect the physiological performance of many marine species. Recent studies have shown substantial reductions in aerobic performance in some teleost fish species, but no change or even enhanced performance in others. Notably lacking, however, are studies on the effects of near-future CO2 conditions on larger meso and apex predators, such as elasmobranchs. The epaulette shark (Hemiscyllium ocellatum) lives on shallow coral reef flats and in lagoons, where it may frequently encounter short-term periods of environmental hypoxia and elevated CO2, especially during nocturnal low tides. Indeed, H. ocellatum is remarkably tolerant to short periods (hours) of hypoxia, and possibly hypercapnia, but nothing is known about its response to prolonged exposure. We exposed H. ocellatum individuals to control (390 µatm) or one of two near-future CO2 treatments (600 or 880 µatm) for a minimum of 60 days and then measured key aspects of their respiratory physiology, namely the resting oxygen consumption rate, which is used to estimate resting metabolic rate, and critical oxygen tension, a proxy for hypoxia sensitivity. Neither of these respiratory attributes was affected by the long-term exposure to elevated CO2. Furthermore, there was no change in citrate synthase activity, a cellular indicator of aerobic energy production. Plasma bicarbonate concentrations were significantly elevated in sharks exposed to 600 and 880 µatm CO2 treatments, indicating that acidosis was probably prevented by regulatory changes in acid–base relevant ions. Epaulette sharks may therefore possess adaptations that confer tolerance to CO2 levels projected to occur in the ocean by the end of this century. It remains uncertain whether other elasmobranchs, especially pelagic species that do not experience such diurnal fluctuations in their environment, will be equally tolerant. PMID:27293668

Participation of reactive oxygen species in diabetes-induced endothelial dysfunction.

PubMed

Zúrová-Nedelcevová, Jana; Navarová, Jana; Drábiková, Katarína; Jancinová, Viera; Petríková, Margita; Bernátová, Iveta; Kristová, Viera; Snirc, Vladimír; Nosál'ová, Viera; Sotníková, Ruzena

2006-12-01

In the present study, the relationship between diabetes-induced hyperglycemia, reactive oxygen species production and endothelium-mediated arterial function was examined. The effect of antioxidant on the reactive oxygen species induced damage was tested. Diabetes was induced by streptozotocin (STZ), 3 x 30 mg/kg i.p., administered on three consecutive days. After 10 weeks of diabetes, the functional state of the endothelium of the aorta was tested, endothelemia evaluation was performed and systolic blood pressure was measured. Reactive oxygen species (ROS) formation in blood and the aorta was measured using luminol-enhanced chemiluminescence (CL). Levels of reduced glutathione (GSH) were determined in the aorta, kidney, and plasma. To study the involvement of hyperglycemia in functional impairment of the endothelium, aortal rings incubated in solution with high glucose concentration were tested in in vitro experiments. After 10 weeks of diabetes, endothelial injury was observed, exhibited by diminished endothelium-dependent relaxation of the aorta, increased endothelemia and by elevated systolic blood pressure. Using luminol-enhanced CL, a significant increase of ROS production was found in arterial tissue and blood. GSH levels were significantly increased in the kidney, while there were no GSH changes in plasma and the aorta. Incubation of aortic rings in solution with high glucose concentration led to impairment of endothelium-dependent relaxation. The synthetic antioxidant SMe1EC2 was able to restore reduced endothelium-mediated relaxation. Our results suggest an important role of hyperglycemia-induced ROS production in mediating endothelial dysfunction in experimental diabetes, confirmed by CL and the protective effect of the antioxidant SMe1EC2.

Duration of effects of acute environmental changes on food anticipatory behaviour, feed intake, oxygen consumption, and cortisol release in Atlantic salmon parr.

PubMed

Folkedal, Ole; Torgersen, Thomas; Olsen, Rolf Erik; Fernö, Anders; Nilsson, Jonatan; Oppedal, Frode; Stien, Lars H; Kristiansen, Tore S

2012-01-18

We compared behavioural and physiological responses and recovery time after different acute environmental challenges in groups of salmon parr. The fish were prior to the study conditioned to a flashing light signalling arrival of food 30 s later to study if the strength of Pavlovian conditioned food anticipatory behaviour can be used to assess how salmon parr cope with various challenges. The effect on anticipatory behaviour was compared to the effect on feed intake and physiological responses of oxygen hyper-consumption and cortisol excretion. The challenges were temperature fluctuation (6.5C° over 4 h), hyperoxia (up to 380% O(2) saturation over 4 h), and intense chasing for 10 min. Cortisol excretion was only elevated after hyperoxia and chasing, and returned to baseline levels after around 3 h or less. Oxygen hyper-consumption persisted for even shorter periods. Feed intake was reduced the first feeding after all challenges and recovered within 3 h after temperature and hyperoxia, but was reduced for days after chasing. Food anticipatory behaviour was reduced for a longer period than feed intake after hyperoxia and was low at least 6 h after chasing. Our findings suggest that a recovery of challenged Atlantic salmon parr to baseline levels of cortisol excretion and oxygen consumption does not mean full recovery of all psychological and physiological effects of environmental challenges, and emphasise the need for measuring several factors including behavioural parameters when assessing fish welfare. Copyright © 2011 Elsevier Inc. All rights reserved.

Are global warming and ocean acidification conspiring against marine ectotherms? A meta-analysis of the respiratory effects of elevated temperature, high CO2 and their interaction.

PubMed

Lefevre, Sjannie

2016-01-01

With the occurrence of global change, research aimed at estimating the performance of marine ectotherms in a warmer and acidified future has intensified. The concept of oxygen- and capacity-limited thermal tolerance, which is inspired by the Fry paradigm of a bell-shaped increase-optimum-decrease-type response of aerobic scope to increasing temperature, but also includes proposed negative and synergistic effects of elevated CO2 levels, has been suggested as a unifying framework. The objectives of this meta-analysis were to assess the following: (i) the generality of a bell-shaped relationship between absolute aerobic scope (AAS) and temperature; (ii) to what extent elevated CO2 affects resting oxygen uptake MO2rest and AAS; and (iii) whether there is an interaction between elevated temperature and CO2. The behavioural effects of CO2 are also briefly discussed. In 31 out of 73 data sets (both acutely exposed and acclimated), AAS increased and remained above 90% of the maximum, whereas a clear thermal optimum was observed in the remaining 42 data sets. Carbon dioxide caused a significant rise in MO2rest in only 18 out of 125 data sets, and a decrease in 25, whereas it caused a decrease in AAS in four out of 18 data sets and an increase in two. The analysis did not reveal clear evidence for an overall correlation with temperature, CO2 regime or duration of CO2 treatment. When CO2 had an effect, additive rather than synergistic interactions with temperature were most common and, interestingly, they even interacted antagonistically on MO2rest and AAS. The behavioural effects of CO2 could complicate experimental determination of respiratory performance. Overall, this meta-analysis reveals heterogeneity in the responses to elevated temperature and CO2 that is not in accordance with the idea of a single unifying principle and which cannot be ignored in attempts to model and predict the impacts of global warming and ocean acidification on marine ectotherms.

Are global warming and ocean acidification conspiring against marine ectotherms? A meta-analysis of the respiratory effects of elevated temperature, high CO2 and their interaction

PubMed Central

Lefevre, Sjannie

2016-01-01

Abstract With the occurrence of global change, research aimed at estimating the performance of marine ectotherms in a warmer and acidified future has intensified. The concept of oxygen- and capacity-limited thermal tolerance, which is inspired by the Fry paradigm of a bell-shaped increase–optimum–decrease-type response of aerobic scope to increasing temperature, but also includes proposed negative and synergistic effects of elevated CO2 levels, has been suggested as a unifying framework. The objectives of this meta-analysis were to assess the following: (i) the generality of a bell-shaped relationship between absolute aerobic scope (AAS) and temperature; (ii) to what extent elevated CO2 affects resting oxygen uptake MO2rest and AAS; and (iii) whether there is an interaction between elevated temperature and CO2. The behavioural effects of CO2 are also briefly discussed. In 31 out of 73 data sets (both acutely exposed and acclimated), AAS increased and remained above 90% of the maximum, whereas a clear thermal optimum was observed in the remaining 42 data sets. Carbon dioxide caused a significant rise in MO2rest in only 18 out of 125 data sets, and a decrease in 25, whereas it caused a decrease in AAS in four out of 18 data sets and an increase in two. The analysis did not reveal clear evidence for an overall correlation with temperature, CO2 regime or duration of CO2 treatment. When CO2 had an effect, additive rather than synergistic interactions with temperature were most common and, interestingly, they even interacted antagonistically on MO2rest and AAS. The behavioural effects of CO2 could complicate experimental determination of respiratory performance. Overall, this meta-analysis reveals heterogeneity in the responses to elevated temperature and CO2 that is not in accordance with the idea of a single unifying principle and which cannot be ignored in attempts to model and predict the impacts of global warming and ocean acidification on marine ectotherms. PMID:27382472

Effects of reactive oxygen species levels in prepared culture media on embryo development: a comparison of two media.

PubMed

Shih, Ying-Fu; Lee, Tsung-Hsien; Liu, Chung-Hsien; Tsao, Hui-Mei; Huang, Chun-Chia; Lee, Maw-Sheng

2014-12-01

This study determined the correlation between the levels of reactive oxygen species (ROS) in prepared culture media and the early development of human embryos. This was an autocontrolled comparison study. A total of 159 patients undergoing in vitro fertilization/intracytoplasmic sperm injection treatment were recruited in this study. The pH values, osmolarity pressures, and ROS levels of 15 batches of two culture media were measured. Sibling oocytes or embryos from individual patients were randomly assigned to two culture groups with Quinn's Advantage Cleavage and Blastocyst media (QAC/QAB) or GIII series cleavage and blastocyst media (G1.3/G2.3). The difference between the two culture groups was analyzed using one-sample t test. The QAC/QAB and G1.3/G2.3 media exhibited similar pH values and osmolarity pressures. However, the prepared QAC/QAB media were characterized to contain lower amounts of ROS than the G1.3/G2.3 media. Furthermore, the blastocysts that developed under the QAC/QAB media were morphologically superior to those that developed under the G1.3/G2.3 media. The elevated ROS levels in culture media were associated with poor development of blastocyst-stage embryos. Measurement of ROS levels may be a valuable process for medium selection or modification. Copyright © 2014. Published by Elsevier B.V.

Oxygen depth profiling by resonant RBS in NiTi after plasma immersion ion implantation

NASA Astrophysics Data System (ADS)

Mändl, S.; Lindner, J. K. N.

2006-08-01

NiTi exhibits super-elastic as well as shape-memory properties, which results in a large potential application field in biomedical technology. Using oxygen ion implantation at elevated temperatures, it is possible to improve the biocompatibility. Resonant Rutherford backscattering spectroscopy (RRBS) is used to investigate the oxygen depth profile obtained after oxygen plasma immersion ion implantation (PIII) at 25 kV and 400-600 °C. At all temperatures, a layered structure consisting of TiO2/Ni3Ti/NiTi was found with sharp interfaces while no discernible content of oxygen inside Ni3Ti or nickel in TiO2 was found. These data are compatible with a titanium diffusion from the bulk towards the implanted oxygen.

Acclimation of respiratory O{sub 2} uptake in green tissues of field-grown native species after long-term exposure to elevated atmospheric CO{sub 2}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Azcon-Bieto, J.; Gonzalez-Meler, M.A.; Doherty, W.

1994-11-01

C{sub 3} and C{sub 4} plants were grown in open-top chambers in the field at two CO{sub 2} concentrations, normal ambient (ambient) and normal ambient + 340 {mu}L L{sup {minus}1} (elevated). Dark oxygen uptake was measured in leaves and stems using a liquid-phase Clark-type oxygen electrode. High CO{sub 2} treatment decreased dark oxygen uptake in stems of Scirpus olneyi (C{sub 3}) and leaves of Lindera benzoin (C{sub 3}) expressed on either a dry weight or area basis. Respiration of Spartina patens (C{sub 4}) leaves was unaffected by CO{sub 2} treatment. Leaf dry weight per unit area was unchanged by CO{submore » 2}, but respiration per unit of carbon or per unit of nitrogen was decreased in the C{sub 3} species grown at high CO{sub 2}. The component of respiration in stems of S. olneyi and leaves of L. benzoin primarily affected by long-term exposure to the elevated CO{sub 2} treatment was the activity of the cytochrome pathway. Elevated CO{sub 2} had no effect on activity and capacity of the alternative pathway in S. olneyi. The cytochrome c oxidase activity, assayed in a cell-free extract, was strongly decreased by growth at high CO{sub 2} in stems of S. olneyi but it was unaffected in S. patens leaves. The activity of cytochrome c oxidase and complex III extracted from mature leaves of L. benzoin was also decreased after one growing season of plant exposure to elevated CO{sub 2} concentration. These results show that in some C{sub 3} species respiration will be reduced when plants are grown in elevated atmospheric CO{sub 2}. The possible physiological causes and implications of these effects are discussed. 34 refs., 1 fig., 6 tabs.« less

Genetic and metabolite diversity of Sardinian populations of Helichrysum italicum.

PubMed

Melito, Sara; Sias, Angela; Petretto, Giacomo L; Chessa, Mario; Pintore, Giorgio; Porceddu, Andrea

2013-01-01

Helichrysum italicum (Asteraceae) is a small shrub endemic to the Mediterranean Basin, growing in fragmented and diverse habitats. The species has attracted attention due to its secondary metabolite content, but little effort has as yet been dedicated to assessing the genetic and metabolite diversity present in these populations. Here, we describe the diversity of 50 H. italicum populations collected from a range of habitats in Sardinia. H. italicum plants were AFLP fingerprinted and the composition of their leaf essential oil characterized by GC-MS. The relationships between the genetic structure of the populations, soil, habitat and climatic variables and the essential oil chemotypes present were evaluated using Bayesian clustering, contingency analyses and AMOVA. The Sardinian germplasm could be partitioned into two AFLP-based clades. Populations collected from the southwestern region constituted a homogeneous group which remained virtually intact even at high levels of K. The second, much larger clade was more diverse. A positive correlation between genetic diversity and elevation suggested the action of natural purifying selection. Four main classes of compounds were identified among the essential oils, namely monoterpenes, oxygenated monoterpenes, sesquiterpenes and oxygenated sesquiterpenes. Oxygenated monoterpene levels were significantly correlated with the AFLP-based clade structure, suggesting a correspondence between gene pool and chemical diversity. The results suggest an association between chemotype, genetic diversity and collection location which is relevant for the planning of future collections aimed at identifying valuable sources of essential oil.

Comparison of the bulk geochemical features and thermal reactivity of kerogens from Mol (Boom Clay), Bure (Callovo-Oxfordian argillite) and Tournemire (Toarcian shales) underground research laboratories.

PubMed

Deniau, I; Devol-Brown, I; Derenne, S; Behar, F; Largeau, C

2008-01-25

Deep argillaceous formations are potential repositories for the long-term disposal of nuclear waste because of their low permeability and high sorption capacity with respect to radioelements and heavy metals. Such sedimentary rocks contain organic matter, mostly macromolecular and insoluble (kerogen). Upon temperature elevation related to high-level long-lived radioactive waste disposal, the kerogen may release significant quantities of gaseous and liquid effluents, especially oxygen-containing ones, which may influence the ability of the clay to retain radionuclides. The aim of the present study is to assess the global geochemical features and the thermal reactivity of the kerogens isolated from samples collected in the Bure and Tournemire sites, France (Callovo-Oxfordian Clay and Toarcian Shales, respectively) and to draw comparisons with data previously obtained for the Mol site, Belgium (Boom Clay). The study is based on a combination of elemental, spectroscopic (FTIR, solid state (13)C NMR) and pyrolytic (Rock-Eval pyrolysis, Curie point pyrolysis-gas chromatography/mass spectrometry) analyses. Different levels of maturity and resulting differences in the relative abundance of oxygen-containing groups were thus observed for the three kerogens. This is linked with differences in their ability to generate CO(2) and various oxygen-containing, low molecular weight, water-soluble compounds under thermal stress, decreasing from Mol to Bure and to Tournemire.

75 FR 54822 - Endangered and Threatened Wildlife and Plants; 12-Month Finding on a Petition To List the Jemez...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-09-09

... be surface active (feeding and mating). Moreover, elevated temperatures lead to increases in oxygen... disease and parasites. Effects from temperature increases are discussed in greater detail under Factor E... distribution and occurrence as well as its oxygen consumption rates and growth rates (Wyman and Hawksley...

Nitrate retention in riparian ground water at natural and elevated nitrate levels in North Central Minnesota

USGS Publications Warehouse

Duff, J.H.; Jackman, A.P.; Triska, F.J.; Sheibley, R.W.; Avanzino, R.J.

2007-01-01

The relationship between local ground water flows and NO3- transport to the channel was examined in three well transects from a natural, wooded riparian zone adjacent to the Shingobee River, MN. The hillslope ground water originated as recharge from intermittently grazed pasture up slope of the site. In the hillslope transect perpendicular to the stream, ground water NO3- concentrations decreased from ???3 mg N L-1 beneath the ridge (80 m from the channel) to 0.01 to 1.0 mg N L-1 at wells 1 to 3 m from the channel. The Cl- concentrations and NO3/Cl ratios decreased toward the channel indicating NO3- dilution and biotic retention. In the bankside well transect parallel to the stream, two distinct ground water environments were observed: an alluvial environment upstream of a relict beaver dam influenced by stream water and a hillslope environment downstream of the relict beaver dam. Nitrate was elevated to levels representative of agricultural runoff in a third well transect looted ???5 m from the stream to assess the effectiveness of the riparian zone as a NO3- sink. Subsurface NO3- injections revealed transport of up to 15 mg N L-1 was nearly conservative in the alluvial riparian environment. Addition of glucose stimulated dissolved oxygen uptake and promoted NO3- retention under both background and elevated NO 3- levels in summer and winter. Disappearance of added NO3- was followed by transient NO2- formation and, in the presence of C2H2, by N2O formation, demonstrating potential denitrification. Under current land use, most NO3- associated with local ground water is biotically retained or diluted before reaching the channel. However, elevating NO 3- levels through agricultural cultivation would likely result in increased NO3- transport to the channel. ?? ASA, CSSA, SSSA.

Different Effects of Oral Contraceptive and Dydrogesterone Treatment on Oxidative Stress Levels in Premenopausal Women.

PubMed

Chen, Jui-Tung; Kotani, Kazuhiko

2018-02-01

The aim of the study was to observe the changes in blood oxidative stress levels by oral contraceptive (OC) and/or dydrogesterone (DG) treatment. A retrospective cohort of 27 premenopausal women with primary dysmenorrhea consisted of the OC treatment group (N = 17) and the DG treatment group (N = 10) by choice of the initial treatment. The OC group included two subgroups: patients with continuous OC treatment (treated for at least 15 months, N = 10) and patients with discontinuous OC treatment (switched to DG treatment after approximately 6 months of initial OC treatment: N = 7). The DG group had 15 months of continuous DG treatment. Blood parameters, including diacron-reactive oxygen metabolites (d-ROMs: an oxidative stress marker), were measured. The d-ROMs level was elevated in the OC group 3 months after initial treatment (mean: from 321 (at baseline) to 512 Carratelli Units (Carr U); P < 0.01), while such changes were not observed in the DG group. The d-ROMs level was reduced in the discontinuous OC subgroup 15 months after initial treatment (from 508 (3 months after initial treatment) to 372 Carr U; P < 0.01), while such changes were not observed in the continuous OC subgroup. The DG group displayed unchanged the d-ROMs level. Replacing OC with DG can attenuate oxidative stress as elevated by OC, thereby alleviating the possible vascular risks with OC treatment.

Facing the River Gauntlet: Understanding the Effects of Fisheries Capture and Water Temperature on the Physiology of Coho Salmon

PubMed Central

Raby, Graham D.; Clark, Timothy D.; Farrell, Anthony P.; Patterson, David A.; Bett, Nolan N.; Wilson, Samantha M.; Willmore, William G.; Suski, Cory D.; Hinch, Scott G.; Cooke, Steven J.

2015-01-01

An improved understanding of bycatch mortality can be achieved by complementing field studies with laboratory experiments that use physiological assessments. This study examined the effects of water temperature and the duration of net entanglement on physiological disturbance and recovery in coho salmon (Oncorhynchus kisutch) after release from a simulated beach seine capture. Heart rate was monitored using implanted electrocardiogram biologgers that allowed fish to swim freely before and after release. A subset of fish was recovered in respirometers to monitor metabolic recovery, and separate groups of fish were sacrificed at different times to assess blood and white muscle biochemistry. One hour after release, fish had elevated lactate in muscle and blood plasma, depleted tissue energy stores, and altered osmoregulatory status, particularly in warmer (15 vs. 10°C) and longer (15 vs. 2 min) capture treatments. A significant effect of entanglement duration on blood and muscle metabolites remained after 4 h. Oxygen consumption rate recovered to baseline within 7–10 h. However, recovery of heart rate to routine levels was longer and more variable, with most fish taking over 10 h, and 33% of fish failing to recover within 24 h. There were no significant treatment effects on either oxygen consumption or heart rate recovery. Our results indicate that fishers should minimize handling time for bycatch and maximize oxygen supply during crowding, especially when temperatures are elevated. Physiological data, such as those presented here, can be used to understand mechanisms that underlie bycatch impairment and mortality, and thus inform best practices that ensure the welfare and conservation of affected species. PMID:25901952

Sediment-Overlying Water Relationships Affecting Wintertime Dissolved Oxygen Conditions in the Big Eau Pleine Reservoir, Wisconsin.

DTIC Science & Technology

1992-07-01

22202-4302. and to the Office of Managel ent and Bidget . P worki Reduction Pfo4ect(07T4-016 Wahington. DC 20S03. -1. AGENCY USE ONLY (Leave blank) 2...higher pool elevation can not be maintained, it is likely that additional aerators must be installed for incremental use to meet periodic heavy oxygen...install additional aerators throughout the reservoir for incremental use as needed to enhance oxygen diffusion processes. The difficulty with this

Rhenium/Oxygen Interactions at Elevated Temperatures

NASA Technical Reports Server (NTRS)

Jacobson, Nathan; Myers, Dwight; Zhu, Dong-Ming; Humphrey, Donald

2000-01-01

The oxidation of pure rhenium is examined from 600-1400 C in oxygen/argon mixtures. Linear weight loss kinetics are observed. Gas pressures, flow rates, and temperatures are methodically varied to determine the rate controlling steps. The reaction at 600 and 800 C appears to be controlled by a chemical reaction step at the surface; whereas the higher temperature reactions appear to be controlled by gas phase diffusion of oxygen to the rhenium surface. Attack of the rhenium appears to be along grain boundaries and crystallographic planes.

Humans permanently occupied the Andean highlands by at least 7 ka

PubMed Central

Stefanescu, Ioana C.; Garcia-Putnam, Alexander; Aldenderfer, Mark S.; Clementz, Mark T.; Murphy, Melissa S.; Llave, Carlos Viviano; Watson, James T.

2017-01-01

High-elevation environments above 2500 metres above sea level (m.a.s.l.) were among the planet's last frontiers of human colonization. Research on the speed and tempo of this colonization process is active and holds implications for understanding rates of genetic, physiological and cultural adaptation in our species. Permanent occupation of high-elevation environments in the Andes Mountains of South America tentatively began with hunter–gatherers around 9 ka according to current archaeological estimates, though the timing is currently debated. Recent observations on the archaeological site of Soro Mik'aya Patjxa (8.0–6.5 ka), located at 3800 m.a.s.l. in the Andean Altiplano, offer an opportunity to independently test hypotheses for early permanent use of the region. This study observes low oxygen (δ18O) and high carbon (δ13C) isotope values in human bone, long travel distances to low-elevation zones, variable age and sex structure in the human population and an absence of non-local lithic materials. These independent lines of evidence converge to support a model of permanent occupation of high elevations and refute logistical and seasonal use models. The results constitute the strongest empirical support to date for permanent human occupation of the Andean highlands by hunter–gatherers before 7 ka. PMID:28680685

Proteinaceous and oligosaccharidic elicitors induce different calcium signatures in the nucleus of tobacco cells.

PubMed

Lecourieux, David; Lamotte, Olivier; Bourque, Stéphane; Wendehenne, David; Mazars, Christian; Ranjeva, Raoul; Pugin, Alain

2005-12-01

We previously reported elevated cytosolic calcium levels in tobacco cells in response to elicitors [D. Lecourieux, C. Mazars, N. Pauly, R. Ranjeva, A. Pugin, Analysis and effects of cytosolic free calcium elevations in response to elicitors in Nicotiana plumbaginifolia cells, Plant Cell 14 (2002) 2627-2641]. These data suggested that in response to elicitors, Ca2+, as a second messenger, was involved in both systemic acquired resistance (RSA) and/or hypersensitive response (HR) depending on calcium signature. Here, we used transformed tobacco cells with apoaequorin expressed in the nucleus to monitor changes in free nuclear calcium concentrations ([Ca2+](nuc)) in response to elicitors. Two types of elicitors are compared: proteins leading to necrosis including four elicitins and harpin, and non-necrotic elicitors including flagellin (flg22) and two oligosaccharidic elicitors, namely the oligogalacturonides (OGs) and the beta-1,3-glucan laminarin. Our data indicate that the proteinaceous elicitors induced a pronounced and sustainable [Ca2+](nuc) elevation, relative to the small effects of oligosaccharidic elicitors. This [Ca2+](nuc) elevation, which seems insufficient to induce cell death, is unlikely to result directly from the diffusion of calcium from the cytosol. The [Ca2+](nuc) rise depends on free cytosolic calcium, IP3, and active oxygen species (AOS) but is independent of nitric oxide.

Experimental Limiting Oxygen Concentrations for Nine Organic Solvents at Temperatures and Pressures Relevant to Aerobic Oxidations in the Pharmaceutical Industry

PubMed Central

2015-01-01

Applications of aerobic oxidation methods in pharmaceutical manufacturing are limited in part because mixtures of oxygen gas and organic solvents often create the potential for a flammable atmosphere. To address this issue, limiting oxygen concentration (LOC) values, which define the minimum partial pressure of oxygen that supports a combustible mixture, have been measured for nine commonly used organic solvents at elevated temperatures and pressures. The solvents include acetic acid, N-methylpyrrolidone, dimethyl sulfoxide, tert-amyl alcohol, ethyl acetate, 2-methyltetrahydrofuran, methanol, acetonitrile, and toluene. The data obtained from these studies help define safe operating conditions for the use of oxygen with organic solvents. PMID:26622165

Reactive Oxygen Species, Vascular Noxs, and Hypertension: Focus on Translational and Clinical Research

PubMed Central

Montezano, Augusto C.

2014-01-01

Abstract Significance: Reactive oxygen species (ROS) are signaling molecules that are important in physiological processes, including host defense, aging, and cellular homeostasis. Increased ROS bioavailability and altered redox signaling (oxidative stress) have been implicated in the onset and/or progression of chronic diseases, including hypertension. Recent Advances: Although oxidative stress may not be the only cause of hypertension, it amplifies blood pressure elevation in the presence of other pro-hypertensive factors, such as salt loading, activation of the renin-angiotensin-aldosterone system, and sympathetic hyperactivity, at least in experimental models. A major source for ROS in the cardiovascular-renal system is a family of nicotinamide adenine dinucleotide phosphate oxidases (Noxs), including the prototypic Nox2-based Nox, and Nox family members: Nox1, Nox4, and Nox5. Critical Issues: Although extensive experimental data support a role for increased ROS levels and altered redox signaling in the pathogenesis of hypertension, the role in clinical hypertension is unclear, as a direct causative role of ROS in blood pressure elevation has yet to be demonstrated in humans. Nevertheless, what is becoming increasingly evident is that abnormal ROS regulation and aberrant signaling through redox-sensitive pathways are important in the pathophysiological processes which is associated with vascular injury and target-organ damage in hypertension. Future Directions: There is a paucity of clinical information related to the mechanisms of oxidative stress and blood pressure elevation, and a few assays accurately measure ROS directly in patients. Such further ROS research is needed in humans and in the development of adequately validated analytical methods to accurately assess oxidative stress in the clinic. Antioxid. Redox Signal. 20, 164–182. PMID:23600794

The effects of elevated temperature and ocean acidification on the metabolic pathways of notothenioid fish

PubMed Central

Enzor, Laura A.; Hunter, Evan M.

2017-01-01

Abstract The adaptations used by notothenioid fish to combat extreme cold may have left these fish poorly poised to deal with a changing environment. As such, the expected environmental perturbations brought on by global climate change have the potential to significantly affect the energetic demands and subsequent cellular processes necessary for survival. Despite recent lines of evidence demonstrating that notothenioid fish retain the ability to acclimate to elevated temperatures, the underlying mechanisms responsible for temperature acclimation in these fish remain largely unknown. Furthermore, little information exists on the capacity of Antarctic fish to respond to changes in multiple environmental variables. We have examined the effects of increased temperature and pCO2 on the rate of oxygen consumption in three notothenioid species, Trematomus bernacchii, Pagothenia borchgrevinki, and Trematomus newnesi. We combined these measurements with analysis of changes in aerobic and anaerobic capacity, lipid reserves, fish condition, and growth rates to gain insight into the metabolic cost associated with acclimation to this dual stress. Our findings indicated that temperature is the major driver of the metabolic responses observed in these fish and that increased pCO2 plays a small, contributing role to the energetic costs of the acclimation response. All three species displayed varying levels of energetic compensation in response to the combination of elevated temperature and pCO2. While P. borchgrevinki showed nearly complete compensation of whole animal oxygen consumption rates and aerobic capacity, T. newnesi and T. bernacchii displayed only partial compensation in these metrics, suggesting that at least some notothenioids may require physiological trade-offs to fully offset the energetic costs of long-term acclimation to climate change related stressors. PMID:28852515

The effects of elevated temperature and ocean acidification on the metabolic pathways of notothenioid fish.

PubMed

Enzor, Laura A; Hunter, Evan M; Place, Sean P

2017-01-01

The adaptations used by notothenioid fish to combat extreme cold may have left these fish poorly poised to deal with a changing environment. As such, the expected environmental perturbations brought on by global climate change have the potential to significantly affect the energetic demands and subsequent cellular processes necessary for survival. Despite recent lines of evidence demonstrating that notothenioid fish retain the ability to acclimate to elevated temperatures, the underlying mechanisms responsible for temperature acclimation in these fish remain largely unknown. Furthermore, little information exists on the capacity of Antarctic fish to respond to changes in multiple environmental variables. We have examined the effects of increased temperature and p CO 2 on the rate of oxygen consumption in three notothenioid species, Trematomus bernacchii , Pagothenia borchgrevinki , and Trematomus newnesi . We combined these measurements with analysis of changes in aerobic and anaerobic capacity, lipid reserves, fish condition, and growth rates to gain insight into the metabolic cost associated with acclimation to this dual stress. Our findings indicated that temperature is the major driver of the metabolic responses observed in these fish and that increased p CO 2 plays a small, contributing role to the energetic costs of the acclimation response. All three species displayed varying levels of energetic compensation in response to the combination of elevated temperature and p CO 2 . While P. borchgrevinki showed nearly complete compensation of whole animal oxygen consumption rates and aerobic capacity, T. newnesi and T. bernacchii displayed only partial compensation in these metrics, suggesting that at least some notothenioids may require physiological trade-offs to fully offset the energetic costs of long-term acclimation to climate change related stressors.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yu, Shu; Cheng, Qiong; Li, Lu

Salidroside is proven to be a neuroprotective agent of natural origin, and its analog, 2-(4-Methoxyphenyl)ethyl-2-acetamido-2-deoxy-β-D-pyranoside (named SalA-4 g), has been synthesized in our lab. In this study, we showed that SalA-4 g promoted neuronal survival and inhibited neuronal apoptosis in primary hippocampal neurons exposed to oxygen and glucose deprivation (OGD) and in rats subjected to ischemia by transient middle cerebral artery occlusion (MCAO), respectively, and that SalA-4 g was more neuroprotective than salidroside. We further found that SalA-4 g elevated glucose uptake in OGD-injured primary hippocampal neurons and increased the expression and recruitment of glucose transporter 3 (GLUT3) in ischemicmore » brain. Signaling analysis revealed that SalA-4 g triggered the phosphorylation of CREB, and increased the expression of PKA RII in primary hippocampal neurons exposed to OGD injury, while inhibition of PKA/CREB by H-89 alleviated the elevation in glucose uptake and GLUT3 expression, and blocked the protective effects of SalA-4 g. Moreover, SalA-4 g was noted to inhibit intracellular Ca{sup 2+} influx and calpain1 activation in OGD-injured primary hippocampal neurons. Our results suggest that SalA-4 g neuroprotection might be mediated by increased glucose uptake and elevated GLUT3 expression through calpain1/PKA/CREB pathway. - Highlights: • A salidroside (Sal) analog (SalA-4 g) is prepared to be more neuroprotective than Sal. • SalA-4 g protected hippocampal neurons from oxygen and glucose deprivation insult. • SalA-4 g reduced ischemic injury after transient middle cerebral artery occlusion in rats. • Neuroprotection of SalA-4 g was mediated by GLUT3 level via calpain/PKA/CREB pathway.« less

Hypoxic Niche-Mediated Regeneration of Hematopoiesis in the Engraftment Window Is Dominantly Affected by Oxygen Tension in the Milieu

PubMed Central

Moirangthem, Ranjita Devi; Singh, Shweta; Adsul, Ashwini; Jalnapurkar, Sapana; Limaye, Lalita

2015-01-01

The bone marrow (BM) microenvironment or the hematopoietic stem cell (HSC) niche is normally hypoxic, which maintains HSC quiescence. Paradoxically, transplanted HSCs rapidly proliferate in this niche. Pretransplant myelosuppression results in a substantial rise in oxygen levels in the marrow microenvironment due to reduced cellularity and consequent low oxygen consumption. Therefore, it may be construed that the rapid proliferation of the engrafted HSCs in the BM niche is facilitated by the transiently elevated oxygen tension in this milieu during the “engraftment window.” To determine whether oxygen tension dominantly affects the regeneration of hematopoiesis in the BM niche, we created an “oxygen-independent hypoxic niche” by treating BM-derived mesenchymal stromal cells (BMSCs) with a hypoxia-mimetic compound, cobalt chloride (CoCl2) and cocultured them with BM-derived HSC-enriched cells under normoxic conditions (HSCs; CoCl2-cocultures). Cocultures with untreated BMSCs incubated under normoxia (control- cocultures) or hypoxia (1% O2; hypoxic-cocultures) were used as comparators. Biochemical analyses showed that though, both CoCl2 and hypoxia evoked comparable signals in the BMSCs, the regeneration of hematopoiesis in their respective cocultures was radically different. The CoCl2-BMSCs supported robust hematopoiesis, while the hypoxic-BMSCs exerted strong inhibition. The hematopoiesis-supportive ability of CoCl2-BMSCs was abrogated if the CoCl2-cocultures were incubated under hypoxia, demonstrating that the prevalent oxygen tension in the milieu dominantly affects the outcome of the HSC-BM niche interactions. Our data suggest that pharmacologically delaying the reestablishment of hypoxia in the BM may boost post-transplant regeneration of hematopoiesis. PMID:26107807

Ventilatory strategies and supportive care in acute respiratory distress syndrome.

PubMed

Luks, Andrew M

2013-11-01

While antiviral therapy is an important component of care in patients with the acute respiratory distress syndrome (ARDS) following influenza infection, it is not sufficient to ensure good outcomes, and additional measures are usually necessary. Patients usually receive high levels of supplemental oxygen to counteract the hypoxemia resulting from severe gas exchange abnormalities. Many patients also receive invasive mechanical ventilation for support for oxygenation, while in resource-poor settings, supplemental oxygen via face mask may be the only available intervention. Patients with ARDS receiving mechanical ventilation should receive lung-protective ventilation, whereby tidal volume is decreased to 6 ml/kg of their predicted weight and distending pressures are maintained ≤ 30 cm H2 O, as well as increased inspired oxygen concentrations and positive end-expiratory pressure (PEEP) to prevent atelectasis and support oxygenation. While these measures are sufficient in most patients, a minority develop refractory hypoxemia and may receive additional therapies, including prone positioning, inhaled vasodilators, extracorporeal membrane oxygenation, recruitment maneuvers followed by high PEEP, and neuromuscular blockade, although recent data suggest that this last option may be warranted earlier in the clinical course before development of refractory hypoxemia. Application of these "rescue strategies" is complicated by the lack of guidance in the literature regarding implementation. While much attention is devoted to these strategies, clinicians must not lose sight of simple interventions that affect patient outcomes including head of bed elevation, prophylaxis against venous thromboembolism and gastrointestinal bleeding, judicious use of fluids in the post-resuscitative phase, and a protocol-based approach to sedation and spontaneous breathing trials. © 2013 Blackwell Publishing Ltd.

Exogenous pyruvate facilitates cancer cell adaptation to hypoxia by serving as an oxygen surrogate

PubMed Central

Yin, Chengqian; He, Dan; Chen, Shuyang; Tan, Xiaoling; Sang, Nianli

2016-01-01

Molecular oxygen is the final electron acceptor in cellular metabolism but cancer cells often become adaptive to hypoxia, which promotes resistance to chemotherapy and radiation. The reduction of endogenous glycolytic pyruvate to lactate is known as an adaptive strategy for hypoxic cells. Whether exogenous pyruvate is required for hypoxic cell proliferation by either serving as an electron acceptor or a biosynthetic substrate remains unclear. By using both hypoxic and ρ0 cells defective in electron transfer chain, we show that exogenous pyruvate is required to sustain proliferation of both cancer and non-cancer cells that cannot utilize oxygen. Particularly, we show that absence of pyruvate led to glycolysis inhibition and AMPK activation along with decreased NAD+ levels in ρ0 cells; and exogenous pyruvate increases lactate yield, elevates NAD+/NADH ratio and suppresses AMPK activation. Knockdown of lactate dehydrogenase significantly inhibits the rescuing effects of exogenous pyruvate. In contrast, none of pyruvate-derived metabolites tested (including acetyl-CoA, α-ketoglutarate, succinate and alanine) can replace pyruvate in supporting ρ0 cell proliferation. Knockdown of pyruvate carboxylase, pyruvate dehydrogenase and citrate synthase do not impair exogenous pyruvate to rescue ρ0 cells. Importantly, we show that exogenous pyruvate relieves ATP insufficiency and mTOR inhibition and promotes proliferation of hypoxic cells, and that well-oxygenated cells release pyruvate, providing a potential in vivo source of pyruvate. Taken together, our data support a novel pyruvate cycle model in which oxygenated cells release pyruvate for hypoxic cells as an oxygen surrogate. The pyruvate cycle may be targeted as a new therapy of hypoxic cancers. PMID:27374086

Exogenous pyruvate facilitates cancer cell adaptation to hypoxia by serving as an oxygen surrogate.

PubMed

Yin, Chengqian; He, Dan; Chen, Shuyang; Tan, Xiaoling; Sang, Nianli

2016-07-26

Molecular oxygen is the final electron acceptor in cellular metabolism but cancer cells often become adaptive to hypoxia, which promotes resistance to chemotherapy and radiation. The reduction of endogenous glycolytic pyruvate to lactate is known as an adaptive strategy for hypoxic cells. Whether exogenous pyruvate is required for hypoxic cell proliferation by either serving as an electron acceptor or a biosynthetic substrate remains unclear. By using both hypoxic and ρ0 cells defective in electron transfer chain, we show that exogenous pyruvate is required to sustain proliferation of both cancer and non-cancer cells that cannot utilize oxygen. Particularly, we show that absence of pyruvate led to glycolysis inhibition and AMPK activation along with decreased NAD+ levels in ρ0 cells; and exogenous pyruvate increases lactate yield, elevates NAD+/NADH ratio and suppresses AMPK activation. Knockdown of lactate dehydrogenase significantly inhibits the rescuing effects of exogenous pyruvate. In contrast, none of pyruvate-derived metabolites tested (including acetyl-CoA, α-ketoglutarate, succinate and alanine) can replace pyruvate in supporting ρ0 cell proliferation. Knockdown of pyruvate carboxylase, pyruvate dehydrogenase and citrate synthase do not impair exogenous pyruvate to rescue ρ0 cells. Importantly, we show that exogenous pyruvate relieves ATP insufficiency and mTOR inhibition and promotes proliferation of hypoxic cells, and that well-oxygenated cells release pyruvate, providing a potential in vivo source of pyruvate. Taken together, our data support a novel pyruvate cycle model in which oxygenated cells release pyruvate for hypoxic cells as an oxygen surrogate. The pyruvate cycle may be targeted as a new therapy of hypoxic cancers.

Cumulative mtDNA damage and mutations contribute to the progressive loss of RGCs in a rat model of glaucoma.

PubMed

Wu, Ji-Hong; Zhang, Sheng-Hai; Nickerson, John M; Gao, Feng-Juan; Sun, Zhongmou; Chen, Xin-Ya; Zhang, Shu-Jie; Gao, Feng; Chen, Jun-Yi; Luo, Yi; Wang, Yan; Sun, Xing-Huai

2015-02-01

Glaucoma is a chronic neurodegenerative disease characterized by the progressive loss of retinal ganglion cells (RGCs). Mitochondrial DNA (mtDNA) alterations have been documented as a key component of many neurodegenerative disorders. However, whether mtDNA alterations contribute to the progressive loss of RGCs and the mechanism whereby this phenomenon could occur are poorly understood. We investigated mtDNA alterations in RGCs using a rat model of chronic intraocular hypertension and explored the mechanisms underlying progressive RGC loss. We demonstrate that the mtDNA damage and mutations triggered by intraocular pressure (IOP) elevation are initiating, crucial events in a cascade leading to progressive RGC loss. Damage to and mutation of mtDNA, mitochondrial dysfunction, reduced levels of mtDNA repair/replication enzymes, and elevated reactive oxygen species form a positive feedback loop that produces irreversible mtDNA damage and mutation and contributes to progressive RGC loss, which occurs even after a return to normal IOP. Furthermore, we demonstrate that mtDNA damage and mutations increase the vulnerability of RGCs to elevated IOP and glutamate levels, which are among the most common glaucoma insults. This study suggests that therapeutic approaches that target mtDNA maintenance and repair and that promote energy production may prevent the progressive death of RGCs. Copyright © 2014 Elsevier Inc. All rights reserved.

Comparing floral and isotopic paleoelevation estimates: Examples from the western United States

NASA Astrophysics Data System (ADS)

Hyland, E. G.; Huntington, K. W.; Sheldon, N. D.; Smith, S. Y.; Strömberg, C. A. E.

2016-12-01

Describing paleoelevations is crucial to understanding tectonic processes and deconvolving the effects of uplift and climate on environmental change in the past. Decades of work has gone into estimating past elevation from various proxy archives, particularly using modern relationships between elevation and temperature, floral assemblage compositions, or oxygen isotope values. While these methods have been used widely and refined through time, they are rarely applied in tandem; here we provide two examples from the western United States using new multiproxy methods: 1) combining clumped isotopes and macrofloral assemblages to estimate paleoelevations along the Colorado Plateau, and 2) combining oxygen isotopes and phytolith methods to estimate paleoelevations within the greater Yellowstone region. Clumped isotope measurements and refined floral coexistence methods from sites on the northern Colorado Plateau like Florissant and Creede (CO) consistently estimate low (< 2km) elevations through the Eocene/Oligocene, suggesting slower uplift and a south-north propagation of the plateau. Oxygen isotope measurements and C4 phytolith estimates from sites surrounding the Yellowstone hotspot consistently estimate moderate uplift (0.2-0.7km) propagating along the hotspot track, suggesting migrating dynamic topography associated with the region. These examples provide support for the emerging practice of using multiproxy methods to estimate paleoelevations for important time periods, and can help integrate environmental and tectonic records of the past.

Oxygen saturation in optic nerve head structures by hyperspectral image analysis.

PubMed

Beach, James; Ning, Jinfeng; Khoobehi, Bahram

2007-02-01

A method is presented for the calculation and visualization of percent blood oxygen saturation from specific tissue structures in hyperspectral images of the optic nerve head (ONH). Trans-pupillary images of the primate optic nerve head and overlying retinal blood vessels were obtained with a hyperspectral imaging (HSI) system attached to a fundus camera. Images were recorded during normal blood flow and after partially interrupting flow to the ONH and retinal circulation by elevation of the intraocular pressure (IOP) from 10 mmHg to 55 mmHg in steps. Percent oxygen saturation was calculated from groups of pixels associated with separate tissue structures, using a linear least-squares curve fit of the recorded hemoglobin spectrum to reference spectra obtained from fully oxygenated and deoxygenated red cell suspensions. Color maps of saturation were obtained from a new algorithm that enables comparison of oxygen saturation from large vessels and tissue areas in hyperspectral images. Percent saturation in retinal vessels and from the average over ONH structures (IOP = 10 mmHg) was (mean +/- SE): artery 81.8 +/- 0.4%, vein 42.6 +/- 0.9%, average ONH 68.3 +/- 0.4%. Raising IOP from 10 mmHg to 55 mmHg for 5 min caused blood oxygen saturation to decrease (mean +/- SE): artery 46.1 +/- 6.2%, vein 36.1 +/- 1.6%, average ONH 41.9 +/- 1.6%. The temporal cup showed the highest saturation at low and high IOP (77.3 +/- 1.0% and 60.1 +/- 4.0%) and the least reduction in saturation at high IOP (22.3%) compared with that of the average ONH (38.6%). A linear relationship was found between saturation indices obtained from the algorithm and percent saturation values obtained by spectral curve fits to calibrated red cell samples. Percent oxygen saturation was determined from hyperspectral images of the ONH tissue and retinal vessels overlying the ONH at normal and elevated IOP. Pressure elevation was shown to reduce blood oxygen saturation in vessels and ONH structures, with the smallest reduction in the ONH observed in the temporal cup. IOP-induced saturation changes were visualized in color maps using an algorithm that follows saturation-dependent changes in the blood spectrum and blood volume differences across tissue. Reduced arterial saturation at high IOP may have resulted from a flow-dependent mechanism.

Impaired Insulin Signaling is Associated with Hepatic Mitochondrial Dysfunction in IR+/−-IRS-1+/− Double Heterozygous (IR-IRS1dh) Mice

PubMed Central

Franko, Andras; Kunze, Alexander; Böse, Marlen; von Kleist-Retzow, Jürgen-Christoph; Paulsson, Mats; Hartmann, Ursula; Wiesner, Rudolf J.

2017-01-01

Mitochondria play a pivotal role in energy metabolism, but whether insulin signaling per se could regulate mitochondrial function has not been identified yet. To investigate whether mitochondrial function is regulated by insulin signaling, we analyzed muscle and liver of insulin receptor (IR)+/−-insulin receptor substrate-1 (IRS-1)+/− double heterozygous (IR-IRS1dh) mice, a well described model for insulin resistance. IR-IRS1dh mice were studied at the age of 6 and 12 months and glucose metabolism was determined by glucose and insulin tolerance tests. Mitochondrial enzyme activities, oxygen consumption, and membrane potential were assessed using spectrophotometric, respirometric, and proton motive force analysis, respectively. IR-IRS1dh mice showed elevated serum insulin levels. Hepatic mitochondrial oxygen consumption was reduced in IR-IRS1dh animals at 12 months of age. Furthermore, 6-month-old IR-IRS1dh mice demonstrated enhanced mitochondrial respiration in skeletal muscle, but a tendency of impaired glucose tolerance. On the other hand, 12-month-old IR-IRS1dh mice showed improved glucose tolerance, but normal muscle mitochondrial function. Our data revealed that deficiency in IR/IRS-1 resulted in normal or even elevated skeletal muscle, but impaired hepatic mitochondrial function, suggesting a direct cross-talk between insulin signaling and mitochondria in the liver. PMID:28556799

Impaired Insulin Signaling is Associated with Hepatic Mitochondrial Dysfunction in IR+/--IRS-1+/- Double Heterozygous (IR-IRS1dh) Mice.

PubMed

Franko, Andras; Kunze, Alexander; Böse, Marlen; von Kleist-Retzow, Jürgen-Christoph; Paulsson, Mats; Hartmann, Ursula; Wiesner, Rudolf J

2017-05-30

Mitochondria play a pivotal role in energy metabolism, but whether insulin signaling per se could regulate mitochondrial function has not been identified yet. To investigate whether mitochondrial function is regulated by insulin signaling, we analyzed muscle and liver of insulin receptor (IR) +/- -insulin receptor substrate-1 (IRS-1) +/- double heterozygous (IR-IRS1dh) mice, a well described model for insulin resistance. IR-IRS1dh mice were studied at the age of 6 and 12 months and glucose metabolism was determined by glucose and insulin tolerance tests. Mitochondrial enzyme activities, oxygen consumption, and membrane potential were assessed using spectrophotometric, respirometric, and proton motive force analysis, respectively. IR-IRS1dh mice showed elevated serum insulin levels. Hepatic mitochondrial oxygen consumption was reduced in IR-IRS1dh animals at 12 months of age. Furthermore, 6-month-old IR-IRS1dh mice demonstrated enhanced mitochondrial respiration in skeletal muscle, but a tendency of impaired glucose tolerance. On the other hand, 12-month-old IR-IRS1dh mice showed improved glucose tolerance, but normal muscle mitochondrial function. Our data revealed that deficiency in IR/IRS-1 resulted in normal or even elevated skeletal muscle, but impaired hepatic mitochondrial function, suggesting a direct cross-talk between insulin signaling and mitochondria in the liver.

Changes in diadenosine tetraphosphate levels in Physarum polycephalum with different oxygen concentrations.

PubMed Central

Garrison, P N; Mathis, S A; Barnes, L D

1989-01-01

Cellular levels of diadenosine tetraphosphate (Ap4A) were measured, by a specific high-pressure liquid chromatography method, in microplasmodia of Physarum polycephalum subjected to different degrees of hypoxia, hyperoxia, and treatment with H2O2. Ap4A levels increased three- to sevenfold under anaerobic conditions, and the microplasmodia remained viable after such treatment. Elevated levels of Ap4A returned to the basal level within 5 to 10 min upon reoxygenation of the microplasmodia. The increases in Ap4A levels were larger in stationary-phase or starved microplasmodia than in fed, log-phase microplasmodia. The maximal increase measured in log-phase microplasmodia was twofold. No significant changes in Ap4A levels occurred in microplasmodia subjected to mild hypoxia, hyperoxia, or treatment with 1 mM H2O2. These results indicate that in P. polycephalum, Ap4A may function in the metabolic response to anaerobic conditions rather than in the response to oxidative stress. PMID:2921243

Assessment of thermal stress adaptation by monitoring Hsp70 and MnSOD in the freshwater gastropod, Bellamya bengalensis (Lamark 1882).

PubMed

Dutta, Sangita Maiti; Mustafi, Soumyajit Banerjee; Raha, Sanghamitra; Chakraborty, Susanta Kumar

2014-12-01

Expression of the stress biomarkers 70-kDa heat shock proteins (Hsp70) and manganese superoxide dismutase (MnSOD) was measured as the molecular basis of adaptive response against increased experimental temperatures (32-40 °C for a span of 24-72 h) on the fresh water molluscan species, Bellamya bengalensis (Lamark 1882). The experimental snail specimens were collected during summer and winter seasons from two contrasting wetlands: an ecorestored (free from human interference) site (SI) and other experiencing anthropogenic stresses (SII). The mortality rate of the B. bengalensis and the immunoblotting of MnSOD and Hsp70 of their digestive glands were performed at regular intervals during the period of heat stress. The SI provided a lower stress environment based on physicochemical parameters such as pH, dissolved oxygen (DO), biological oxygen demand (BOD), chemical oxygen demand (COD), and alkalinity for the survival of test species, although both sites experienced mortality due to thermal stresses. The parity in protein expressions displayed a uniform mode of adaptive impact to temperature elevations in both field and laboratory exposure. The Hsp70 expression was minimal at lower thermal stress, but increased with a rise in temperature. It is very likely that higher Hsp70 levels are not directly related to survival or adaptation. In contrast, MnSOD levels appeared to be an indicator of adaptive responses vis-a-vis survival of the animals. So, the expression levels of a universal free radical scavenger like MnSOD are recognized as a potential biomarker in a bioindicator species like Bellamya.

Perspectives on Proterozoic surface ocean redox from iodine contents in ancient and recent carbonate

NASA Astrophysics Data System (ADS)

Hardisty, Dalton S.; Lu, Zunli; Bekker, Andrey; Diamond, Charles W.; Gill, Benjamin C.; Jiang, Ganqing; Kah, Linda C.; Knoll, Andrew H.; Loyd, Sean J.; Osburn, Magdalena R.; Planavsky, Noah J.; Wang, Chunjiang; Zhou, Xiaoli; Lyons, Timothy W.

2017-04-01

The Proterozoic Eon hosted the emergence and initial recorded diversification of eukaryotes. Oxygen levels in the shallow marine settings critical to these events were lower than today's, although how much lower is debated. Here, we use concentrations of iodate (the oxidized iodine species) in shallow-marine limestones and dolostones to generate the first comprehensive record of Proterozoic near-surface marine redox conditions. The iodine proxy is sensitive to both local oxygen availability and the relative proximity to anoxic waters. To assess the validity of our approach, Neogene-Quaternary carbonates are used to demonstrate that diagenesis most often decreases and is unlikely to increase carbonate-iodine contents. Despite the potential for diagenetic loss, maximum Proterozoic carbonate iodine levels are elevated relative to those of the Archean, particularly during the Lomagundi and Shuram carbon isotope excursions of the Paleo- and Neoproterozoic, respectively. For the Shuram anomaly, comparisons to Neogene-Quaternary carbonates suggest that diagenesis is not responsible for the observed iodine trends. The baseline low iodine levels in Proterozoic carbonates, relative to the Phanerozoic, are linked to a shallow oxic-anoxic interface. Oxygen concentrations in surface waters would have at least intermittently been above the threshold required to support eukaryotes. However, the diagnostically low iodine data from mid-Proterozoic shallow-water carbonates, relative to those of the bracketing time intervals, are consistent with a dynamic chemocline and anoxic waters that would have episodically mixed upward and laterally into the shallow oceans. This redox instability may have challenged early eukaryotic diversification and expansion, creating an evolutionary landscape unfavorable for the emergence of animals.

Mycobacterium tuberculosis Ser/Thr protein kinase B mediates an oxygen-dependent replication switch

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ortega, Corrie; Liao, Reiling; Anderson, Lindsey N.

In the majority of cases, Mycobacterium tuberculosis (Mtb) infections are clinically latent, characterized by little or no bacterial replication and drug tolerance. Low oxygen tension is a major host factor inducing bacteriostasis, but the molecular mechanisms driving oxygen-dependent replication are poorly understood. Mtb encodes eleven serine/threonine protein kinases, a family of signaling molecules known to regulate similar replicative adaptations in other bacteria. Here, we tested the role of serine/threonine phosphorylation in the Mtb response to altered oxygen status, using an in vitro model of latency (hypoxia) and reactivation (reaeration). Broad kinase inhibition compromised survival of Mtb in hypoxia. Activity-based proteinmore » profiling and genetic mutation identified PknB as the kinase critical for surviving hypoxia. Mtb replication was highly sensitive to changes in PknB levels in aerated culture, and even more so in hypoxia. A mutant overexpressing PknB specifically in hypoxia showed a 10-fold loss in viability in low oxygen conditions. In contrast, chemically reducing PknB activity during hypoxia specifically compromised resumption of growth during reaeration. These data support a model in which PknB activity is reduced to achieve bacteriostasis, and elevated when replication resumes. Together, these data show that phosphosignaling controls replicative transitions associated with latency and reactivation, that PknB is a major regulator of these transitions, and that PknB could provide a highly vulnerable therapeutic target at every step of the Mtb life cycle - active disease, latency, and reactivation.« less

Electronic properties and surface reactivity of SrO-terminated SrTiO3 and SrO-terminated iron-doped SrTiO3

PubMed Central

Staykov, Aleksandar; Tellez, Helena; Druce, John; Wu, Ji; Ishihara, Tatsumi; Kilner, John

2018-01-01

Abstract Surface reactivity and near-surface electronic properties of SrO-terminated SrTiO3 and iron doped SrTiO3 were studied with first principle methods. We have investigated the density of states (DOS) of bulk SrTiO3 and compared it to DOS of iron-doped SrTiO3 with different oxidation states of iron corresponding to varying oxygen vacancy content within the bulk material. The obtained bulk DOS was compared to near-surface DOS, i.e. surface states, for both SrO-terminated surface of SrTiO3 and iron-doped SrTiO3. Electron density plots and electron density distribution through the entire slab models were investigated in order to understand the origin of surface electrons that can participate in oxygen reduction reaction. Furthermore, we have compared oxygen reduction reactions at elevated temperatures for SrO surfaces with and without oxygen vacancies. Our calculations demonstrate that the conduction band, which is formed mainly by the d-states of Ti, and Fe-induced states within the band gap of SrTiO3, are accessible only on TiO2 terminated SrTiO3 surface while the SrO-terminated surface introduces a tunneling barrier for the electrons populating the conductance band. First principle molecular dynamics demonstrated that at elevated temperatures the surface oxygen vacancies are essential for the oxygen reduction reaction. PMID:29535797

Cancer cells growing on perfused 3D collagen model produced higher reactive oxygen species level and were more resistant to cisplatin compared to the 2D model.

PubMed

Liu, Qingxi; Zhang, Zijiang; Liu, Yupeng; Cui, Zhanfeng; Zhang, Tongcun; Li, Zhaohui; Ma, Wenjian

2018-03-01

Three-dimensional (3D) collagen scaffold models, due to their ability to mimic the tissue and organ structure in vivo, have received increasing interest in drug discovery and toxicity evaluation. In this study, we developed a perfused 3D model and studied cellular response to cytotoxic drugs in comparison with traditional 2D cell cultures as evaluated by cancer drug cisplatin. Cancer cells grown in perfused 3D environments showed increased levels of reactive oxygen species (ROS) production compared to the 2D culture. As determined by growth analysis, cells in the 3D culture, after forming a spheroid, were more resistant to the cancer drug cisplatin compared to that of the 2D cell culture. In addition, 3D culturing cells showed elevated level of ROS, indicating a physiological change or the formation of a microenvironment that resembles tumor cells in vivo. These data revealed that cellular response to drugs for cells growing in 3D environments are dramatically different from that of 2D cultured cells. Thus, the perfused 3D collagen scaffold model we report here might be a potentially very useful tool for drug analysis.

Chronic alcoholism in rats induces a compensatory response, preserving brain thiamine diphosphate, but the brain 2-oxo acid dehydrogenases are inactivated despite unchanged coenzyme levels.

PubMed

Parkhomenko, Yulia M; Kudryavtsev, Pavel A; Pylypchuk, Svetlana Yu; Chekhivska, Lilia I; Stepanenko, Svetlana P; Sergiichuk, Andrej A; Bunik, Victoria I

2011-06-01

Thiamine-dependent changes in alcoholic brain were studied using a rat model. Brain thiamine and its mono- and diphosphates were not reduced after 20 weeks of alcohol exposure. However, alcoholism increased both synaptosomal thiamine uptake and thiamine diphosphate synthesis in brain, pointing to mechanisms preserving thiamine diphosphate in the alcoholic brain. In spite of the unchanged level of the coenzyme thiamine diphosphate, activities of the mitochondrial 2-oxoglutarate and pyruvate dehydrogenase complexes decreased in alcoholic brain. The inactivation of pyruvate dehydrogenase complex was caused by its increased phosphorylation. The inactivation of 2-oxoglutarate dehydrogenase complex (OGDHC) correlated with a decrease in free thiols resulting from an elevation of reactive oxygen species. Abstinence from alcohol following exposure to alcohol reactivated OGDHC along with restoration of the free thiol content. However, restoration of enzyme activity occurred before normalization of reactive oxygen species levels. Hence, the redox status of cellular thiols mediates the action of oxidative stress on OGDHC in alcoholic brain. As a result, upon chronic alcohol consumption, physiological mechanisms to counteract the thiamine deficiency and silence pyruvate dehydrogenase are activated in rat brain, whereas OGDHC is inactivated due to impaired antioxidant ability. © 2011 The Authors. Journal of Neurochemistry © 2011 International Society for Neurochemistry.

Extracorporeal membrane oxygenation causes loss of intestinal epithelial barrier in the newborn piglet.

PubMed

Kurundkar, Ashish R; Killingsworth, Cheryl R; McIlwain, R Britt; Timpa, Joseph G; Hartman, Yolanda E; He, Dongning; Karnatak, Rajendra K; Neel, Mary L; Clancy, John P; Anantharamaiah, G M; Maheshwari, Akhil

2010-08-01

Extracorporeal membrane oxygenation (ECMO) is an important life-support system used in neonates and young children with intractable cardiorespiratory failure. In this study, we used our porcine neonatal model of venoarterial ECMO to investigate whether ECMO causes gut barrier dysfunction. We subjected 3-wk-old previously healthy piglets to venoarterial ECMO for up to 8 h and evaluated gut mucosal permeability, bacterial translocation, plasma levels of bacterial products, and ultrastructural changes in gut epithelium. We also measured plasma lipopolysaccharide (LPS) levels in a small cohort of human neonates receiving ECMO. In our porcine model, ECMO caused a rapid increase in gut mucosal permeability within the first 2 h of treatment, leading to a 6- to 10-fold rise in circulating bacterial products. These changes in barrier function were associated with cytoskeletal condensation in epithelial cells, which was explained by phosphorylation of a myosin II regulatory light chain. In support of these findings, we also detected elevated plasma LPS levels in human neonates receiving ECMO, indicating a similar loss of gut barrier function in these infants. On the basis of these data, we conclude that ECMO is an independent cause of gut barrier dysfunction and bacterial translocation may be an important contributor to ECMO-related inflammation.

Extracorporeal Membrane Oxygenation Causes Loss of Intestinal Epithelial Barrier in the Newborn Piglet

PubMed Central

Kurundkar, Ashish R.; Killingsworth, Cheryl R.; McILwain, R. Britt; Timpa, Joseph G.; Hartman, Yolanda E.; He, Dongning; Karnatak, Rajendra K.; Neel, Mary Lauren; Clancy, John P.; Anantharamaiah, G. M.; Maheshwari, Akhil

2010-01-01

Extracorporeal membrane oxygenation (ECMO) is an important life-support system used in neonates and young children with intractable cardiorespiratory failure. In this study, we used our porcine neonatal model of venoarterial ECMO to investigate whether ECMO causes gut barrier dysfunction. We subjected 3-week-old previously-healthy piglets to venoarterial ECMO for up to 8 hours and evaluated gut mucosal permeability, bacterial translocation, plasma levels of bacterial products, and ultrastructural changes in gut epithelium. We also measured plasma lipopolysaccharide (LPS) levels in a small cohort of human neonates receiving ECMO. In our porcine model, ECMO caused a rapid increase in gut mucosal permeability within the first 2 hours of treatment, leading to a 6–10 fold rise in circulating bacterial products. These changes in barrier function were associated with cytoskeletal condensation in epithelial cells, which was explained by phosphorylation of a myosin II regulatory light chain. In support of these findings, we also detected elevated plasma LPS levels in human neonates receiving ECMO, indicating a similar loss of gut barrier function in these infants. Based on these data, we conclude that ECMO is an independent cause of gut barrier dysfunction, and that bacterial translocation may be an important contributor to ECMO-related inflammation. PMID:20442689

The combined effect of pressure and oxygen concentration on piloted ignition of a solid combustible

Treesearch

Sara McAllister; Carlos Fernandez-Pello; David Urban; Gary Ruff

2010-01-01

There are a number of situations when fires may occur at low pressures and oxygen concentrations that are different than standard atmospheric conditions, such as in buildings at high elevation, airplanes, and spacecraft. The flammability of materials may be affected by these environmental conditions. Since ignition delay is a measure of material flammability and...

PRODUCTION OF HAFNIUM METAL

DOEpatents

Elger, G.W.; Boubel, R.W.

1963-01-01

This patent deals with a process of producing pure Hf metal from oxygen- contaminated gaseous Hf chloride. The oxygen compounds in the chioride gas are halogenated by contacting the gas at elevated temperature with Cl/sub 2/ in the presence of C. The Hf chloride, still in gaseous form, is contacted with molten Mg whereby Hf metal is formed and condensed on the Mg. (AEC)

Studying neuroprotective effect of Atorvastatin as a small molecule drug on high glucose-induced neurotoxicity in undifferentiated PC12 cells: role of NADPH oxidase.

PubMed

Rayegan, Samira; Dehpour, Ahmad Reza; Sharifi, Ali Mohammad

2017-02-01

Overproduction of reactive oxygen species (ROS) by NADPH oxidase (NOX) activation has been considered the essential mechanism induced by hyperglycemia in various tissues. However, there is no comprehensive study on the role of NOXs in high glucose (HG)-induced toxic effect in neural tissues. Recently, a therapeutic strategy in oxidative related pathologies has been introduced by blocking the undesirable actions of NOX enzymes by small molecules. The protective roles of Statins in ameliorating oxidative stress by NOX inhibition have been shown in some tissues except neural. We hypothesized then, that different NOXs may have role in HG-induced neural cell injury. Furthermore, we postulate that Atorvastatin as a small molecule may modulate this NOXs activity to protect neural cells. Undifferentiated PC12 cells were treated with HG (140 mM/24 h) in the presence and absence of Atorvastatin (1 μM/96 h). The cell viability was measured by MTT assay and the gene and protein expressions profile of NOX (1-4) were determined by RT-PCR and western blotting, respectively. Levels of ROS and malondialdehyde (MDA) were also evaluated. Gene and protein expression levels of NOX (1-4) and consequently ROS and MDA levels were elevated in HG-treated PC12 cells. Atorvastatin could significantly decrease HG-induced NOXs, ROS and MDA elevation and improve impaired cell viability. It can be concluded that HG could elevate NOXs activity, ROS and MDA levels in neural tissues and Atorvastatin as a small molecule NOX inhibitor drug may prevent and delay diabetic complications, particularly neuropathy.

Astroglial pentose phosphate pathway rates in response to high-glucose environments

PubMed Central

Takahashi, Shinichi; Izawa, Yoshikane; Suzuki, Norihiro

2012-01-01

ROS (reactive oxygen species) play an essential role in the pathophysiology of diabetes, stroke and neurodegenerative disorders. Hyperglycaemia associated with diabetes enhances ROS production and causes oxidative stress in vascular endothelial cells, but adverse effects of either acute or chronic high-glucose environments on brain parenchymal cells remain unclear. The PPP (pentose phosphate pathway) and GSH participate in a major defence mechanism against ROS in brain, and we explored the role and regulation of the astroglial PPP in response to acute and chronic high-glucose environments. PPP activity was measured in cultured neurons and astroglia by determining the difference in rate of 14CO2 production from [1-14C]glucose and [6-14C]glucose. ROS production, mainly H2O2, and GSH were also assessed. Acutely elevated glucose concentrations in the culture media increased PPP activity and GSH level in astroglia, decreasing ROS production. Chronically elevated glucose environments also induced PPP activation. Immunohistochemical analyses revealed that chronic high-glucose environments induced ER (endoplasmic reticulum) stress (presumably through increased hexosamine biosynthetic pathway flux). Nuclear translocation of Nrf2 (nuclear factor-erythroid 2 p45 subunit-related factor 2), which regulates G6PDH (glyceraldehyde-6-phosphate dehydrogenase) by enhancing transcription, was also observed in association with BiP (immunoglobulin heavy-chain-binding protein) expression. Acute and chronic high-glucose environments activated the PPP in astroglia, preventing ROS elevation. Therefore a rapid decrease in glucose level seems to enhance ROS toxicity, perhaps contributing to neural damage when insulin levels given to diabetic patients are not properly calibrated and plasma glucose levels are not adequately maintained. These findings may also explain the lack of evidence for clinical benefits from strict glycaemic control during the acute phase of stroke. PMID:22300409

Laurentide Ice-Sheet Meltwater Sources to the Gulf of Mexico During the Last Deglaciation: Assessing Data Reconstructions Using Water Isotope Enabled Simulations

NASA Astrophysics Data System (ADS)

Vetter, L.; LeGrande, A. N.; Ullman, D. J.; Carlson, A. E.

2017-12-01

Sediment cores from the Gulf of Mexico show evidence of meltwater derived from the Laurentide Ice Sheet during the last deglaciation. Recent studies using geochemical measurements of individual foraminifera suggest changes in the oxygen isotopic composition of the meltwater as deglaciation proceeded. Here we use the water isotope enabled climate model simulations (NASA GISS ModelE-R) to investigate potential sources of meltwater within the ice sheet. We find that initial melting of the ice sheet from the southern margin contributed an oxygen isotope value reflecting a low-elevation, local precipitation source. As deglacial melting proceeded, meltwater delivered to the Gulf of Mexico had a more negative oxygen isotopic value, which the climate model simulates as being sourced from the high-elevation, high-latitude interior of the ice sheet. This study demonstrates the utility of combining stable isotope analyses with climate model simulations to investigate past changes in the hydrologic cycle.

Short-term and long-term prognostic outcomes of patients with ST-segment elevation myocardial infarction complicated by profound cardiogenic shock undergoing early extracorporeal membrane oxygenator-assisted primary percutaneous coronary intervention.

PubMed

Chung, Sheng-Ying; Tong, Meng-Shen; Sheu, Jiunn-Jye; Lee, Fan-Yen; Sung, Pei-Hsun; Chen, Chien-Jen; Yang, Cheng-Hsu; Wu, Chiung-Jen; Yip, Hon-Kan

2016-11-15

This study investigated the 30-day and long-term prognostic outcomes in patients with ST-segment elevation myocardial infarction (STEMI) complicated with profound cardiogenic shock (CS) undergoing early routine extracorporeal membrane oxygenator (ECMO)-assisted primary percutaneous coronary intervention (PCI). Between December 2005 and December 2014, 65 consecutive STEMI patients with profound CS underwent routine ECMO-supported primary PCI. The incidences of acute pulmonary edema, respiratory failure with requirement of mechanical ventilatory support upon presentation, and 30-day mortality rate were 100%, 95.4%, and 43.1%, respectively. The duration of hospitalization, mean long-term follow-up, and survival rate were 32.1±53.1 (days), 733.6±986.7 (days), and 32.3%, respectively. The mean APACHE score (32.6±8.3 vs. 28.5±7.5), peak serum creatinine level (4.3±2.4 vs. 1.7±1.2mg/dL), incidences of failed ECMO weaning (57.1% vs. 0%), successful ECMO weaning but in-hospital death (40.0% vs. 0%) were significantly lower in 30-day survivors than those in non-survivors (all p<0.05), whereas final thrombolysis in myocardial infarction (TIMI)-3 flow [53.6% vs. 91.9%] showed an opposite pattern compared to that of APACHE score in the two groups (p<0.02). Multivariate analysis demonstrated that unsuccessful reperfusion, failed ECMO weaning, and peak creatinine level were independent predictors of 30-day mortality (all p<0.01). Early ECMO-supported primary PCI in STEMI patients with profound CS was feasible as a life-saving strategy with acceptable 30-day and long-term prognostic outcomes. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Cell Wall Invertase Promotes Fruit Set under Heat Stress by Suppressing ROS-Independent Cell Death.

PubMed

Liu, Yong-Hua; Offler, Christina E; Ruan, Yong-Ling

2016-09-01

Reduced cell wall invertase (CWIN) activity has been shown to be associated with poor seed and fruit set under abiotic stress. Here, we examined whether genetically increasing native CWIN activity would sustain fruit set under long-term moderate heat stress (LMHS), an important factor limiting crop production, by using transgenic tomato (Solanum lycopersicum) with its CWIN inhibitor gene silenced and focusing on ovaries and fruits at 2 d before and after pollination, respectively. We found that the increase of CWIN activity suppressed LMHS-induced programmed cell death in fruits. Surprisingly, measurement of the contents of H2O2 and malondialdehyde and the activities of a cohort of antioxidant enzymes revealed that the CWIN-mediated inhibition on programmed cell death is exerted in a reactive oxygen species-independent manner. Elevation of CWIN activity sustained Suc import into fruits and increased activities of hexokinase and fructokinase in the ovaries in response to LMHS Compared to the wild type, the CWIN-elevated transgenic plants exhibited higher transcript levels of heat shock protein genes Hsp90 and Hsp100 in ovaries and HspII17.6 in fruits under LMHS, which corresponded to a lower transcript level of a negative auxin responsive factor IAA9 but a higher expression of the auxin biosynthesis gene ToFZY6 in fruits at 2 d after pollination. Collectively, the data indicate that CWIN enhances fruit set under LMHS through suppression of programmed cell death in a reactive oxygen species-independent manner that could involve enhanced Suc import and catabolism, HSP expression, and auxin response and biosynthesis. © 2016 American Society of Plant Biologists. All rights reserved.

Accumulation of electrophilic aldehydes during postovulatory aging of mouse oocytes causes reduced fertility, oxidative stress, and apoptosis.

PubMed

Lord, Tessa; Martin, Jacinta H; Aitken, R John

2015-02-01

With increasing periods of time following ovulation, the metaphase II (MII)-stage oocyte experiences overproduction of reactive oxygen species and elevated levels of lipid peroxidation that are implicitly linked with functional deficiencies acquired during postovulatory oocyte aging. We have demonstrated that the electrophilic aldehydes 4-hydroxynonenal (4HNE), malondialdehyde, and acrolein are by-products of nonenzymatic lipid peroxidation in the murine MII-stage oocyte, adducting to multiple proteins within the cell. The covalent modification of oocyte proteins by these aldehydes increased with extended periods of time postovulation; the mitochondrial protein succinate dehydrogenase (SDHA) was identified as a primary target for 4HNE adduction. Time- and dose-dependent studies revealed that exposure to elevated levels of electrophilic aldehydes causes mitochondrial reactive oxygen species production, lipid peroxidation, loss of mitochondrial membrane potential, and eventual apoptosis within the MII oocyte, presumably as a consequence of electron transport chain collapse following SDHA adduction. Additionally, we have determined that short-term exposure to low doses of 4HNE dramatically impairs the oocyte's ability to participate in fertilization and support embryonic development; however, this loss of functionality can be prevented by supplementation with the antioxidant penicillamine. In conclusion, this study has revealed that the accumulation of electrophilic aldehydes is linked to postovulatory oocyte aging, causing reduced fertility, oxidative stress, and apoptosis of this highly specialized cell. These data highlight the importance of timely fertilization of the mammalian oocyte postovulation and emphasize the potential advantages associated with antioxidant supplementation of oocyte culture medium in circumstances where reinsemination of oocytes may be desirable (i.e., rescue intracytoplasmic sperm injection), or where in vitro fertilization may be delayed. © 2015 by the Society for the Study of Reproduction, Inc.

Increased sensitivity to apoptosis induced by methotrexate is mediated by Jun N-terminal kinase

PubMed Central

Spurlock, Charles F.; Aune, Zachary T.; Tossberg, John T.; Collins, Patrick L.; Aune, Jessica P.; Huston, Joseph W.; Crooke, Philip S.; Olsen, Nancy J.; Aune, Thomas M.

2011-01-01

Objective Low-dose methotrexate [MTX] is an effective therapy for rheumatoid arthritis yet its mechanism of action is incompletely understood. Here, we explored induction of apoptosis by MTX. Methods We employed flow cytometry to assess changes in levels of intracellular proteins, reactive oxygen species [ROS], and apoptosis.Quantitative polymerase chain reaction was usedtoassess changes in transcript levels of select target genes in response to MTX. Results MTX does not directly induce apoptosis but rather ‘primes’ cells for markedly increased sensitivity to apoptosis via either mitochondrial or death receptor pathways by a Jun N-terminal kinase [JNK]-dependent mechanism. Increased sensitivity to apoptosis is mediated, at least in part, by MTX-dependent production of reactive oxygen species, JNK activation and JNK-dependent induction of genes whose protein products promote apoptosis. Supplementation with tetrahydrobiopterin blocks these methotrexate-induced effects. Subjects with rheumatoid arthritis on low-dose MTX therapy express elevated levels of the JNK-target gene, JUN. Conclusions Our results support a model whereby methotrexate inhibits reduction of dihydrobiopterin to tetrahydrobiopterin resulting in increased production of ROS, increased JNK activity and increased sensitivity to apoptosis. The finding of increased JUN levels in subjects with RA taking low-dose MTX supports the notion that this pathway is activated by MTX, in vivo, and may contribute to efficacy of MTX in inflammatory disease. PMID:21618198

A new cell morphotype among methane oxidizers: a spiral-shaped obligately microaerophilic methanotroph from northern low-oxygen environments.

PubMed

Danilova, Olga V; Suzina, Natalia E; Van De Kamp, Jodie; Svenning, Mette M; Bodrossy, Levente; Dedysh, Svetlana N

2016-11-01

Although representatives with spiral-shaped cells are described for many functional groups of bacteria, this cell morphotype has never been observed among methanotrophs. Here, we show that spiral-shaped methanotrophic bacteria do exist in nature but elude isolation by conventional approaches due to the preference for growth under micro-oxic conditions. The helical cell shape may enable rapid motility of these bacteria in water-saturated, heterogeneous environments with high microbial biofilm content, therefore offering an advantage of fast cell positioning under desired high methane/low oxygen conditions. The pmoA genes encoding a subunit of particulate methane monooxygenase from these methanotrophs form a new genus-level lineage within the family Methylococcaceae, type Ib methanotrophs. Application of a pmoA-based microarray detected these bacteria in a variety of high-latitude freshwater environments including wetlands and lake sediments. As revealed by the environmental pmoA distribution analysis, type Ib methanotrophs tend to live very near the methane source, where oxygen is scarce. The former perception of type Ib methanotrophs as being typical for thermal habitats appears to be incorrect because only a minor proportion of pmoA sequences from these bacteria originated from environments with elevated temperatures.

Dexamethasone inhibits activation of monocytes/macrophages in a milieu rich in 27-oxygenated cholesterol.

PubMed

Kim, Bo-Young; Son, Yonghae; Lee, Jeonga; Choi, Jeongyoon; Kim, Chi Dae; Bae, Sun Sik; Eo, Seong-Kug; Kim, Koanhoi

2017-01-01

Molecular mechanisms underlying the decreased number of macrophages and T cells in the arteries of cholesterol-fed-rabbits following dexamethasone administration are unknown. We investigated the possibility that dexamethasone could affect activation of monocytic cells induced by oxygenated derivatives of cholesterol (oxysterols) using THP-1 monocyte/macrophage cells. 27-Hydroxycholesterol (27OHChol), an oxysterol elevated with hypercholesterolemia, enhanced production of CCL2, known as MCP1, chemokine from monocytes/macrophages and migration of the monocytic cells, but the CCL2 production and the cell migration were reduced by treatment with dexamethasone. Dexamethasone inhibited superproduction of CCL2 induced by 27OHChol plus LPS and attenuated transcription of matrix metalloproteinase 9 as well as secretion of its active gene product induced by 27OHChol. The drug downregulated cellular and surface levels of CD14 and blocked release of soluble CD14 without altering transcription of the gene. Dexamethasone also inhibited expression and phosphorylation of the NF-κB p65 subunit enhanced by 27OHChol. Collectively, these results indicate that dexamethasone inhibits activation of monocytes/macrophages in response to 27OHChol, thereby leading to decreased migration of inflammatory cells in milieu rich in oxygenated derivatives of cholesterol.

Dexamethasone inhibits activation of monocytes/macrophages in a milieu rich in 27-oxygenated cholesterol

PubMed Central

Kim, Bo-Young; Son, Yonghae; Lee, Jeonga; Choi, Jeongyoon; Kim, Chi Dae; Bae, Sun Sik; Eo, Seong-Kug

2017-01-01

Molecular mechanisms underlying the decreased number of macrophages and T cells in the arteries of cholesterol-fed-rabbits following dexamethasone administration are unknown. We investigated the possibility that dexamethasone could affect activation of monocytic cells induced by oxygenated derivatives of cholesterol (oxysterols) using THP-1 monocyte/macrophage cells. 27-Hydroxycholesterol (27OHChol), an oxysterol elevated with hypercholesterolemia, enhanced production of CCL2, known as MCP1, chemokine from monocytes/macrophages and migration of the monocytic cells, but the CCL2 production and the cell migration were reduced by treatment with dexamethasone. Dexamethasone inhibited superproduction of CCL2 induced by 27OHChol plus LPS and attenuated transcription of matrix metalloproteinase 9 as well as secretion of its active gene product induced by 27OHChol. The drug downregulated cellular and surface levels of CD14 and blocked release of soluble CD14 without altering transcription of the gene. Dexamethasone also inhibited expression and phosphorylation of the NF-κB p65 subunit enhanced by 27OHChol. Collectively, these results indicate that dexamethasone inhibits activation of monocytes/macrophages in response to 27OHChol, thereby leading to decreased migration of inflammatory cells in milieu rich in oxygenated derivatives of cholesterol. PMID:29236764

Short-term acute hypercapnia affects cellular responses to trace metals in the hard clams Mercenaria mercenaria.

PubMed

Ivanina, Anna V; Beniash, Elia; Etzkorn, Markus; Meyers, Tiffany B; Ringwood, Amy H; Sokolova, Inna M

2013-09-15

Estuarine and coastal habitats experience large fluctuations of environmental factors such as temperature, salinity, partial pressure of CO2 ( [Formula: see text] ) and pH; they also serve as the natural sinks for trace metals. Benthic filter-feeding organisms such as bivalves are exposed to the elevated concentrations of metals in estuarine water and sediments that can strongly affect their physiology. The effects of metals on estuarine organisms may be exacerbated by other environmental factors. Thus, a decrease in pH caused by high [Formula: see text] (hypercapnia) can modulate the effects of trace metals by affecting metal bioavailability, accumulation or binding. To better understand the cellular mechanisms of interactions between [Formula: see text] and trace metals in marine bivalves, we exposed isolated mantle cells of the hard clams (Mercenaria mercenaria) to different levels of [Formula: see text] (0.05, 1.52 and 3.01 kPa) and two major trace metal pollutants - cadmium (Cd) and copper (Cu). Elevated [Formula: see text] resulted in a decrease in intracellular pH (pHi) of the isolated mantle cells from 7.8 to 7.4. Elevated [Formula: see text] significantly but differently affected the trace metal accumulation by the cells. Cd uptake was suppressed at elevated [Formula: see text] levels while Cu accumulation has greatly accelerated under hypercapnic conditions. Interestingly, at higher extracellular Cd levels, labile intracellular Cd(2+) concentration remained the same, while intracellular levels of free Zn(2+) increased suggesting that Cd(2+) substitutes bound Zn(2+) in these cells. In contrast, Cu exposure did not affect intracellular Zn(2+) but led to a profound increase in the intracellular levels of labile Cu(2+) and Fe(2+). An increase in the extracellular concentrations of Cd and Cu led to the elevated production of reactive oxygen species under the normocapnic conditions (0.05 kPa [Formula: see text] ); surprisingly, this effect was mitigated in hypercapnia (1.52 and 3.01 kPa). Overall, our data reveal complex and metal-specific interactions between the cellular effects of trace metals and [Formula: see text] in clams and indicate that variations in environmental [Formula: see text] may modulate the biological effects of trace metals in marine organisms. Copyright © 2013 Elsevier B.V. All rights reserved.

AGEs/sRAGE, a novel risk factor in the pathogenesis of end-stage renal disease.

PubMed

Prasad, Kailash; Dhar, Indu; Zhou, Qifeng; Elmoselhi, Hamdi; Shoker, Muhammad; Shoker, Ahmed

2016-12-01

Interaction of advanced glycation end products (AGEs) with its cell-bound receptor (RAGE) results in cell dysfunction through activation of nuclear factor kappa-B, increase in expression and release of inflammatory cytokines, and generation of oxygen radicals. Circulating soluble receptors, soluble receptor (sRAGE), endogenous secretory receptor (esRAGE) and cleaved receptor (cRGAE) act as decoy for RAGE ligands and thus have cytoprotective effects. Low levels of sRAGE and esRAGE have been proposed as biomarkers for many diseases. However sRAGE and esRAGE levels are elevated in diabetes and chronic renal diseases and still tissue injury occurs. It is possible that increases in levels of AGEs are greater than increases in the levels of soluble receptors in these two diseases. Some new parameters have to be used which could be an universal biomarkers for cell dysfunction. It is hypothesized that increases in serum levels of AGEs are greater than the increases in the soluble receptors, and that the levels of AGEs is correlated with soluble receptors and that the ratios of AGEs/sRAGE, AGEs/esRAGE and AGEs/cRAGE are elevated in patients with end-stage renal disease (ESRD) and would serve as an universal risk marker for ESRD. The study subject comprised of 88 patients with ESRD and 20 healthy controls. AGEs, sRAGE and esRAGE were measured using commercially available enzyme linked immune assay kits. cRAGE was calculated by subtracting esRAGE from sRAGE. The data show that the serum levels of AGEs, sRAGE, cRAGE are elevated and that the elevation of AGEs was greater than those of soluble receptors. The ratios of AGEs/sRAGE, AGEs/esRAGE and AGEs/cRAGE were elevated and the elevation was similar in AGEs/sRAGE and AGEs/cRAGE but greater than AGEs/esRAGE. The sensitivity, specificity, accuracy, and positive and negative predictive value of AGEs/sRAGE and AGEs/cRAGE were 86.36 and 84.88 %, 86.36 and 80.95 %, 0.98 and 0.905, 96.2 and 94.8 %, and 61.29 and 56.67 % respectively. There was a positive correlation of sRAGE with esRAGE and cRAGE, and AGEs with esRAGE; and negative correlation between sRAGE and AGEs/sRAGE, esRAGE and AGES/esRAGE, and cRAGE and AGES/cRAGE. In conclusion, AGEs/sRAGE, AGEs/cRAGE and AGEs/esRAGE may serve as universal risk biomarkers for ESRD and that AGEs/sRAGE and AGEs/cRAGE are better risk biomarkers than AGEs/esRAGE.

Interdependent genotoxic mechanisms of monomethylarsonous acid: Role of ROS-induced DNA damage and poly(ADP-ribose) polymerase-1 inhibition in the malignant transformation of urothelial cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wnek, Shawn M.; Kuhlman, Christopher L.; Camarillo, Jeannie M.

2011-11-15

Exposure of human bladder urothelial cells (UROtsa) to 50 nM of the arsenic metabolite, monomethylarsonous acid (MMA{sup III}), for 12 weeks results in irreversible malignant transformation. The ability of continuous, low-level MMA{sup III} exposure to cause an increase in genotoxic potential by inhibiting repair processes necessary to maintain genomic stability is unknown. Following genomic insult within cellular systems poly(ADP-ribose) polymerase-1 (PARP-1), a zinc finger protein, is rapidly activated and recruited to sites of DNA strand breaks. When UROtsa cells are continuously exposed to 50 nM MMA{sup III}, PARP-1 activity does not increase despite the increase in MMA{sup III}-induced DNA single-strandmore » breaks through 12 weeks of exposure. When UROtsa cells are removed from continuous MMA{sup III} exposure (2 weeks), PARP-1 activity increases coinciding with a subsequent decrease in DNA damage levels. Paradoxically, PARP-1 mRNA expression and protein levels are elevated in the presence of continuous MMA{sup III} indicating a possible mechanism to compensate for the inhibition of PARP-1 activity in the presence of MMA{sup III}. The zinc finger domains of PARP-1 contain vicinal sulfhydryl groups which may act as a potential site for MMA{sup III} to bind, displace zinc ion, and render PARP-1 inactive. Mass spectrometry analysis demonstrates the ability of MMA{sup III} to bind a synthetic peptide representing the zinc-finger domain of PARP-1, and displace zinc from the peptide in a dose-dependent manner. In the presence of continuous MMA{sup III} exposure, continuous 4-week zinc supplementation restored PARP-1 activity levels and reduced the genotoxicity associated with MMA{sup III}. Zinc supplementation did not produce an overall increase in PARP-1 protein levels, decrease the levels of MMA{sup III}-induced reactive oxygen species, or alter Cu-Zn superoxide dismutase levels. Overall, these results present two potential interdependent mechanisms in which MMA{sup III} may increase the susceptibility of UROtsa cells to genotoxic insult and/or malignant transformation: elevated levels of MMA{sup III}-induced DNA damage through the production of reactive oxygen species, and the direct MMA{sup III}-induced inhibition of PARP-1.« less

Biochemical modifications in Pinus pinaster Ait. as a result of environmental pollution.

PubMed

Acquaviva, Rosaria; Vanella, Luca; Sorrenti, Valeria; Santangelo, Rosa; Iauk, Liliana; Russo, Alessandra; Savoca, Francesca; Barbagallo, Ignazio; Di Giacomo, Claudia

2012-11-01

Exposure to chemical pollution can cause significant damage to plants by imposing conditions of oxidative stress. Plants combat oxidative stress by inducing antioxidant metabolites, enzymatic scavengers of activated oxygen and heat shock proteins. The accumulation of these proteins, in particular heat shock protein 70 and heme oxygenase, is correlated with the acquisition of thermal and chemical adaptations and protection against oxidative stress. In this study, we used Pinus pinaster Ait. collected in the areas of Priolo and Aci Castello representing sites with elevated pollution and reference conditions, respectively. The presence of heavy metals and the levels of markers of oxidative stress (lipid hydroperoxide levels, thiol groups, superoxide dismutase activity and expression of heat shock protein 70, heme oxygenase and superoxide dismutase) were evaluated, and we measured in field-collected needles the response to environmental pollution. P. pinaster Ait. collected from a site characterized by industrial pollution including heavy metals had elevated stress response as indicated by significantly elevated lipid hydroperoxide levels and decreased thiol groups. In particular, we observed that following a chronic chemical exposure, P. pinaster Ait. showed significantly increased expression of heat shock protein 70, heme oxygenase and superoxide dismutase. This increased expression may have protective effects against oxidative stress and represents an adaptative cellular defence mechanism. These results suggest that evaluation of heme oxygenase, heat shock protein 70 and superoxide dismutase expression in P. pinaster Ait. could represent a useful tool for monitoring environmental contamination of a region and to better understand mechanisms involved in plant defence and stress tolerance.

Berberine improves endothelial function by inhibiting endoplasmic reticulum stress in the carotid arteries of spontaneously hypertensive rats.

PubMed

Liu, Limei; Liu, Jian; Huang, Zhengxiang; Yu, Xiaoxing; Zhang, Xinyu; Dou, Dou; Huang, Yu

2015-03-20

Activation of endoplasmic reticulum (ER) stress in endothelial cells leads to increased oxidative stress and often results in cell death, which has been implicated in hypertension. The present study investigated the effects of berberine, a botanical alkaloid purified from Coptidis rhizoma, on ER stress in spontaneously hypertensive rats (SHRs) and the underling mechanism. Isolated carotid arteries from normotensive WKYs and SHRs were suspended in myograph for isometric force measurement. Protein phosphorylations and expressions were determined by Western blotting. Reactive oxygen species (ROS) level was measured by DHE staining. SHR carotid arteries exhibited exaggerated acetylcholine-triggered endothelium-dependent contractions (EDCs) and elevated ROS accumulation compared with WKY arteries. Moreover, Western blot analysis revealed the reduced AMPK phosphorylation, increased eIF2α phosphorylation, and elevated levels of ATF3, ATF6, XBP1 and COX-2 in SHR carotid arteries while these pathological alterations were reversed by 12 h-incubation with berberine. Furthermore, AMPK inhibitor compound C or dominant negative AMPK adenovirus inhibited the effects of berberine on above-mentioned marker proteins and EDCs. More importantly, ROS scavengers, tempol and tiron plus DETCA, or ER stress inhibitors, 4-PBA and TUCDA normalized the elevated levels of ROS and COX-2 expression, and attenuated EDCs in SHR arteries. Taken together, the present results suggest that berberine reduces EDCs likely through activating AMPK, thus inhibiting ER stress and subsequently scavenging ROS leading to COX-2 down-regulation in SHR carotid arteries. The present study thus provides additional insights into the vascular beneficial effects of berberine in hypertension. Copyright © 2015 Elsevier Inc. All rights reserved.

Metabolic effects of physiological levels of caffeine in myotubes.

PubMed

Schnuck, Jamie K; Gould, Lacey M; Parry, Hailey A; Johnson, Michele A; Gannon, Nicholas P; Sunderland, Kyle L; Vaughan, Roger A

2018-02-01

Caffeine has been shown to stimulate multiple major regulators of cell energetics including AMP-activated protein kinase (AMPK) and Ca 2+ /calmodulin-dependent protein kinase II (CaMKII). Additionally, caffeine induces peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) and mitochondrial biogenesis. While caffeine enhances oxidative metabolism, experimental concentrations often exceed physiologically attainable concentrations through diet. This work measured the effects of low-level caffeine on cellular metabolism and gene expression in myotubes, as well as the dependence of caffeine's effects on the nuclear receptor peroxisome proliferator-activated receptor beta/delta (PPARβ/δ). C2C12 myotubes were treated with various doses of caffeine for up to 24 h. Gene and protein expression were measured via qRT-PCR and Western blot, respectively. Cellular metabolism was determined via oxygen consumption and extracellular acidification rate. Caffeine significantly induced regulators of mitochondrial biogenesis and oxidative metabolism. Mitochondrial staining was suppressed in PPARβ/δ-inhibited cells which was rescued by concurrent caffeine treatment. Caffeine-treated cells also displayed elevated peak oxidative metabolism which was partially abolished following PPARβ/δ inhibition. Similar to past observations, glucose uptake and GLUT4 content were elevated in caffeine-treated cells, however, glycolytic metabolism was unaltered following caffeine treatment. Physiological levels of caffeine appear to enhance cell metabolism through mechanisms partially dependent on PPARβ/δ.

Method for producing electricity from a fuel cell having solid-oxide ionic electrolyte

DOEpatents

Mason, David M.

1984-01-01

Stabilized quadrivalent cation oxide electrolytes are employed in fuel cells at elevated temperatures with a carbon and/or hydrogen containing fuel anode and an oxygen cathode. The fuel cell is operated at elevated temperatures with conductive metallic coatings as electrodes and desirably having the electrolyte surface blackened. Of particular interest as the quadrivalent oxide is zirconia.

A Review of Human Health and Ecological Risks due to CO2 Exposure

NASA Astrophysics Data System (ADS)

Hepple, R. P.; Benson, S. M.

2001-05-01

This paper presents an overview of the human health and ecological consequences of exposure to elevated levels of carbon dioxide (CO2) in the context of geologic carbon sequestration. The purpose of this effort is to provide a baseline of information to guide future efforts in risk assessment for CO2 sequestration. Scenarios for hazardous CO2 exposure include surface facility leaks, leaks from abandoned or aging wells, and leakage from geologic CO2 storage structures. Amounts of carbon in various reservoirs, systems, and applications were summarized, and the levels of CO2 encountered in nature and everyday life were compared along with physiologically relevant concentrations. Literature pertaining to CO2 occupational exposure limits, regulations, monitoring, and ecological consequences was reviewed. The OSHA, NIOSH, and ACGIH occupational exposure standards are 0.5% CO2 averaged over a 40 hour week, 3% average for a short-term (15 minute) exposure, and 4% as the maximum instantaneous limit considered immediately dangerous to life and health. All three conditions must be satisfied at all times. Any detrimental effects of low-level CO2 exposure are reversible, including the long-term metabolic compensation required by chronic exposure to 3% CO2. Breathing rate doubles at 3% CO2 and is four times the normal rate at 5% CO2. According to occupational exposure and controlled atmosphere research into CO2 toxicology, CO2 is hazardous via direct toxicity at levels above 5%, concentrations not encountered in nature outside of volcanic settings and water-logged soils. Small leaks do not present any danger to people unless the CO2 does not disperse quickly enough through atmospheric mixing but accumulates instead in depressions and confined spaces. These dangers are the result of CO2 being more dense than air. Carbon dioxide is regulated for diverse purposes but never as a toxic substance. Catastrophic incidents involving large amounts and/or rapid release of CO2 such as Lake Nyos in Cameroon, Mammoth Mountain in California, Dieng Volcanic Complex in Java, Indonesia, and industrial accidents with CO2 fire suppression systems teach that slow leakage rates and effective dilution must be proven to ensure human and environmental safety. Monitoring CO2 levels in occupational settings is done with reliable IR sensors. Remote sensing of low levels of CO2 over long distances cannot be done easily yet, although LIDAR, an airborne laser technique under development, may have good potential. The environmental impacts of elevated CO2 levels on vegetation are being investigated now in free-air CO2 enrichment studies. In general, persistent elevated CO2 levels cause a change in species composition, favoring C3 plants over C4 or CAM. The ecological effects of catastrophic releases are severe but depend upon (a) release rate and amount, (b) surface topography and rate of atmospheric mixing (c) exposure concentrations and duration, (d) the respiratory mechanism of the form of life under discussion, (e) its tolerance for oxygen deprivation, and (f) its ability to maintain homeostatic pH levels. Suppression of root respiration due to elevated soil-gas CO2 concentrations and acidifiction of the root zone are known mechanisms of tree-kill. Soil-gas CO2 in the tree-kill areas at Mammoth Mountain exceeded 20-30% at 15 cm depth. Surface masses of concentrated CO2 probably smother the canopy through oxygen deprivation, but the precise mechanism is not known. Lake Nyos and Mammoth Mountain reveal that catastrophic releases can result in complete dead zones.

Experimental limiting oxygen concentrations for nine organic solvents at temperatures and pressures relevant to aerobic oxidations in the pharmaceutical industry

DOE PAGES

Osterberg, Paul M.; Niemeier, Jeffry K.; Welch, Christopher J.; ...

2014-12-06

Applications of aerobic oxidation methods in pharmaceutical manufacturing are limited in part because mixtures of oxygen gas and organic solvents often create the potential for a flammable atmosphere. To address this issue, limiting oxygen concentration (LOC) values, which define the minimum partial pressure of oxygen that supports a combustible mixture, have been measured for nine commonly used organic solvents at elevated temperatures and pressures. The solvents include acetic acid, N-methylpyrrolidone, dimethyl sulfoxide, tert-amyl alcohol, ethyl acetate, 2-methyltetrahydrofuran, methanol, acetonitrile, and toluene. Furthermore, the data obtained from these studies help define safe operating conditions for the use of oxygen with organicmore » solvents.« less

The Precambrian Biogeochemical Carbon Isotopic Record: Contributions of Thermal Versus Biological Processes

NASA Technical Reports Server (NTRS)

DesMarais, David J.; DeVincenzi, Donald L. (Technical Monitor)

2000-01-01

Superplumes offer a new approach for understanding global C cycles. Isotopes help to discern the impacts of geological, environmental and biological processes ujpun the evolution of these cycles. For example, C-13/C-12 values of coeval sedimentary organics and carbonates give global estimates of the fraction of C buried as organics (Forg), which today lies near 0.2. Before Oxygenic photosynthesis arose, our biosphere obtained reducing power for biosynthesis solely from thermal volatiles and rock alteration. Thus Forg was dominated by the mantle redox state, which has remained remarkably constant for greater than Gy. Recent data confirm that the long-term change in Forg had been small, indicating that the mantle redox buffer remains important even today. Oxygenic photosynthesis enabled life to obtain additional reducing power by splitting the water molecule. Accordingly, biological organic production rose above the level constrained by the mantle-derived flux of reduced species. For example, today, chemoautotrophs harvesting energy from hydrothermal emanations can synthesize at most between 0.2 x 10(exp 12) and 2x 10(exp 12) mol C yr-1 of organic C globally. In contrast, global photosynthetic productivity is estimated at 9000 x 10(exp 12) mol C yr-1. Occasionally photosynthetic productivity did contribute to dramatically -elevated Forg values (to 0.4 or more) as evidenced by very high carbonate C-13/C-12. The interplay between biological, tectonic and other environmental factors is illustrated by the mid-Archean to mid-Proterozoic isotopic record. The relatively constant C-13/C-12 values of Archean carbonates support the view that photosynthetically-driven Forg increases were not yet possible. In contrast, major excursions in C-13/C-12, and thus also in Forg, during the early Proterozoic confirmed the global importance of oxygenic photosynthesis by that time. Remarkably, the superplume event at 1.9 Ga did not trigger another major Forg increase, despite the favorable conditions for organic burial that were evidenced by elevated sea levels and higher black shale abundances. Perhaps those superplume-rated processes that favored enhanced organic burial were offset by the ability of mantle-derived redox buffering, which was enhanced during the superplume event, to limit excursions in Forg.

Responses of the brackish-water amphipod Gammarus duebeni (crustacea) to saline sewage

NASA Astrophysics Data System (ADS)

Jones, M. B.; Johnson, I.

Soon after the openiing of the Looe sewage treatment works (Cornwall, southwest England) in 1973, it became colonized by the brackish-water amphipod Gammarus duebeni Liljeborg. The works is unusual as it operates with saline sewage and has a tidally-based pattern of salinity fluctuation (S=13 to 34). Various responses of this unique amphipod population (sewage amphipods) have been compared with G. duebeni from the adjacent Looe River estuary (estuarine amphipods) in an attempt to identify long-term responses to sewage. Sewage amphipods were significantly smaller than their estuarine equivalents; the sewage population was biased significantly to males, whereas the sex ratio of the estuarine population significantly favours females. Compared with the estuary, the consistently lower oxygen levels in the works were reflected in significant differences in metabolism. Sewage amphipods maintained high levels of activity under hypoxia ( e.g. swimming), and the higher survival and lower rates of lactic acid accumulation under anoxia than estuarine individuals. In addition, sewage amphipods recovered more rapidly from anoxia and had a lower critical oxygen tension (p c) than estuarine amphipods. Sewage amphipods are exposed to higher levels of heavy metals associated with the domestic sewage and zinc concentrations are particularly elevated in the works. Exposure to elevated zinc concentrations resulted in similar patterns of body zinc uptake for sewage and estuarine Gammarus at high (30) and low (10) salinity, with zinc regulation apparently occuring to an external threshold of 200 γmgZn·dm -3. No consistent interpopulational differences in the effect ofzinc on zinc uptake or on osmoregulation have been identified. However, sewage amphipods had higher survival at all zinc/salinity combinations compared with estuarine individuals. These indicate that sewage amphipods are adapted to the unusual combination of conditions prevailing in the treatment works and, if reproductive isolation is confirmed, suggest that the speciation process may have commenced.

Higher fine particulate matter and temperature levels impair exercise capacity in cardiac patients.

PubMed

Giorgini, Paolo; Rubenfire, Melvyn; Das, Ritabrata; Gracik, Theresa; Wang, Lu; Morishita, Masako; Bard, Robert L; Jackson, Elizabeth A; Fitzner, Craig A; Ferri, Claudio; Brook, Robert D

2015-08-01

Fine particulate matter (PM2.5) air pollution and variations in ambient temperature have been linked to increased cardiovascular morbidity and mortality. However, no large-scale study has assessed their effects on directly measured aerobic functional capacity among high-risk patients. Using a cross-sectional observational design, we evaluated the effects of ambient PM2.5 and temperature levels over 7 days on cardiopulmonary exercise test results performed among 2078 patients enrolling into a cardiac rehabilitation programme at the University of Michigan (from January 2003 to August 2011) using multiple linear regression analyses (controlling for age, sex, body mass index). Peak exercise oxygen consumption was significantly decreased by approximately 14.9% per 10 μg/m(3) increase in ambient PM2.5 levels (median 10.7 μg/m(3), IQR 10.1 μg/m(3)) (lag days 6-7). Elevations in PM2.5 were also related to decreases in ventilatory threshold (lag days 5-7) and peak heart rate (lag days 2-3) and increases in peak systolic blood pressure (lag days 4-5). A 10°C increase in temperature (median 10.5°C, IQR 17.5°C) was associated with reductions in peak exercise oxygen consumption (20.6-27.3%) and ventilatory threshold (22.9-29.2%) during all 7 lag days. In models including both factors, the outcome associations with PM2.5 were attenuated whereas the effects of temperature remained significant. Short-term elevations in ambient PM2.5, even at low concentrations within current air quality standards, and/or higher temperatures were associated with detrimental changes in aerobic exercise capacity, which can be linked to a worse quality of life and cardiovascular prognosis among cardiac rehabilitation patients. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Longevity of animals under reactive oxygen species stress and disease susceptibility due to global warming.

PubMed

Paital, Biswaranjan; Panda, Sumana Kumari; Hati, Akshaya Kumar; Mohanty, Bobllina; Mohapatra, Manoj Kumar; Kanungo, Shyama; Chainy, Gagan Bihari Nityananda

2016-02-26

The world is projected to experience an approximate doubling of atmospheric CO2 concentration in the next decades. Rise in atmospheric CO2 level as one of the most important reasons is expected to contribute to raise the mean global temperature 1.4 °C-5.8 °C by that time. A survey from 128 countries speculates that global warming is primarily due to increase in atmospheric CO2 level that is produced mainly by anthropogenic activities. Exposure of animals to high environmental temperatures is mostly accompanied by unwanted acceleration of certain biochemical pathways in their cells. One of such examples is augmentation in generation of reactive oxygen species (ROS) and subsequent increase in oxidation of lipids, proteins and nucleic acids by ROS. Increase in oxidation of biomolecules leads to a state called as oxidative stress (OS). Finally, the increase in OS condition induces abnormality in physiology of animals under elevated temperature. Exposure of animals to rise in habitat temperature is found to boost the metabolism of animals and a very strong and positive correlation exists between metabolism and levels of ROS and OS. Continuous induction of OS is negatively correlated with survivability and longevity and positively correlated with ageing in animals. Thus, it can be predicted that continuous exposure of animals to acute or gradual rise in habitat temperature due to global warming may induce OS, reduced survivability and longevity in animals in general and poikilotherms in particular. A positive correlation between metabolism and temperature in general and altered O2 consumption at elevated temperature in particular could also increase the risk of experiencing OS in homeotherms. Effects of global warming on longevity of animals through increased risk of protein misfolding and disease susceptibility due to OS as the cause or effects or both also cannot be ignored. Therefore, understanding the physiological impacts of global warming in relation to longevity of animals will become very crucial challenge to biologists of the present millennium.

The Accuracy of Pulse Spectroscopy for Detecting Hypoxemia and Coexisting Methemoglobin or Carboxyhemoglobin.

PubMed

Kulcke, Axel; Feiner, John; Menn, Ingolf; Holmer, Amadeus; Hayoz, Josef; Bickler, Philip

2016-06-01

Pulse spectroscopy is a new noninvasive technology involving hundreds of wavelengths of visible and infrared light, enabling the simultaneous quantitation of multiple types of normal and dysfunctional hemoglobin. We evaluated the accuracy of a first-generation pulse spectroscopy system (V-Spec™ Monitoring System, Senspec, Germany) in measuring oxygen saturation (SpO2) and detecting carboxyhemoglobin (COHb) or methemoglobin (MetHb), alone or simultaneously, with hypoxemia. Nineteen volunteers were fitted with V-Spec probes on the forehead and fingers. A radial arterial catheter was placed for blood sampling during (1) hypoxemia with arterial oxygen saturations (SaO2) of 100% to 58.5%; (2) normoxia with MetHb and COHb increased to approximately 10%; (3) 10% COHb or MetHb combined with hypoxemia with SaO2 of 100% to 80%. Standard measures of pulse-oximetry performance were calculated: bias (pulse spectroscopy measured value - arterial measured value) mean ± SD and root-mean-square error (Arms). The SpO2 bias for SaO2 approximately 60% to 100% was 0.06% ± 1.30% and Arms of 1.30%. COHb bias was 0.45 ± 1.63, with an Arms of 1.69% overall, and did not degrade substantially during moderate hypoxemia. MetHb bias was 0.36 ± 0.80 overall and stayed small with hypoxemia. Arms was 0.88 and was <3% at all levels of SaO2 and MetHb. Hypoxemia was also accurately detected by pulse spectroscopy at elevated levels of COHb. At elevated MetHb levels, a substantial negative bias developed, -10.3 at MetHb >10%. Pulse spectroscopy accurately detects hypoxemia, MetHb, and COHb. The technology also accurately detects these dysfunctional hemoglobins during hypoxemia. Future releases of this device may have an improved SpO2 algorithm that is more robust with methemoglobinemia.

Saltwater intrusion coupled with drought accelerates carbon loss from a brackish coastal wetland

NASA Astrophysics Data System (ADS)

Wilson, B.; Troxler, T.

2017-12-01

Coastal wetlands, such as the Everglades, are critical ecosystems for blue carbon (C) storage, yet this storage capacity is vulnerable to environmental change, such as saltwater intrusion and altered hydrology. Saltwater intrusion can stress vegetation and bring new metabolites for microbial respiration, thereby altering the C cycle. Drought can reduce the depth of water covering the wetland soil, and, in extreme cases, lead to exposed soil surface. This increases oxygen levels, thus speeding up C decomposition and potentially leading to peat collapse. The combined effects of both saltwater intrusion and drought on coastal marshes, however, are still uncertain, but recent evidence suggests that saltwater intrusion accelerates C loss from wetlands when coupled with drought. Our objective was to determine the change in CO2 flux, decomposition, root and shoot production, and elevation in a brackish water marsh under conditions of drought and elevated salinity. During the onset of drought, soil CO2 efflux increased by 124% and 237% in the ambient and elevated salinity treatments, respectively, compared to the control. Within one month, elevated salinity decreased net ecosystem production (NEP) by 40%, while after 6 months it had decreased by 85%. During the onset of the drought, there was no difference in NEP with ambient salinity between the inundated and exposed monoliths (-3.4 ± 0.8 vs. -4.2 ± 2.0 μmol CO2 m-2 s-1, respectively). However, drought conditions in the elevated salinity treatment resulted in more CO2 release in the exposed monoliths than the inundated monoliths (1.5 ± 0.4 vs. -0.5 ± 0.3 μmol CO2 m-2 s-1, respectively). Elevation change collected at the end of the experiment will allow us to test if elevated salinity combined with drought contributes to peat collapse, and what mechanisms of ecosystem C cycling has the greatest influence. While the restoration of water flows to the southern Everglades is hypothesized to mitigate the periods of drought and slow down saltwater intrusion, this restoration has not occurred yet. Given accelerating sea level rise, increasing frequencies of saltwater intrusion coupled with drought could accelerate C loss from these coastal marshes.

Liquid oxygen-compatible filament-winding matrix resin

NASA Technical Reports Server (NTRS)

Harrison, E. S.

1973-01-01

Polyurethanes derived from hydroxy terminated polyperfluoro propylene oxide prepolymers were evaluated as matrix resins for filament wound composites which would be exposed to liquid (and 100% gaseous) oxygen environments. A number of structural modifications were brought about by variations in prepolymer molecular weight, and alternative curing agents which allowed retention of the oxygen compatibility. Although satisfactory performance was achieved at sub-ambient temperatures, the derived composites suffered considerable property loss at ambient or slightly elevated temperatures. To attain overall effectiveness of the composite system, upgrading of the polymer thermomechanical properties must first be achieved.

Effects of temperature on the metabolic response to feeding in Python molurus.

PubMed

Wang, Tobias; Zaar, Morten; Arvedsen, Sine; Vedel-Smith, Christina; Overgaard, Johannes

2002-11-01

As ectothermic vertebrates, reptiles undergo diurnal and seasonal changes in body temperature, which affect many biological functions. In conjunction with a general review regarding the effects of temperature on digestion in reptiles, we describe the effects of various temperatures (20-35 degrees C) on the metabolic response to digestion in the Burmese python (Python molurus). The snakes were fed mice amounting to 20% of their body weight and gas exchange (oxygen uptake and CO(2) production) were measured until digestion had ended and gas exchange returned to fasting levels. Elevated temperature was associated with a faster and larger metabolic increase after ingestion, and the time required to return to fasting levels was markedly longer at low temperature. The factorial increase between fasting oxygen consumption (VO(2)) and maximal VO(2) during digestion was, however, similar at all temperatures studied. Furthermore, the integrated SDA response was not affected by temperature suggesting the costs associated with digestion are temperature-independent. Other studies on reptiles show that digestive efficiency is only marginally affected by temperature and we conclude that selection of higher body temperatures during digestion (postprandial thermophilic response) primarily reduces the time required for digestion.

Assessment of acute toxicity of carbofuran in Macrobrachium olfersii (Wiegmann, 1836) at different temperature levels.

PubMed

Barbieri, Edison; Moreira, Priscila; Luchini, Luiz Alberto; Hidalgo, Karla Ruiz; Muñoz, Alejandro

2016-01-01

Carbofuran (2,3-dihydro-2,2-dimethyl-7-benzofuranyl methylcarbamate; C12H15NO3) is one of the most toxic carbamate pesticides. For acute toxicity of carbofuran, juveniles of Macrobrachium olfersii were exposed to different concentrations of carbofuran using the static renewal method at different temperature levels (15, 20 and 25°C) at pH 7.0. The main purpose of the present study was to detect the acute toxicity of carbofuran to M. olfersii and investigate its effects on oxygen consumption and ammonium excretion; these tests have not been carried out in this species before. First, the acute toxicity - median lethal concentration - of carbofuran to M. olfersii for 24, 48, 72 and 96 h was examined, which resulted in the following values: 1.64, 1.22, 0.86 and 0.42 mg L(-1), respectively. Furthermore, we also found that carbofuran caused an inhibition in oxygen consumption of 60.6, 65.3 and 66.2% with respect to the control. In addition, after separate exposures to carbofuran, elevations in ammonium excretion were more than 500% with respect to the control. © The Author(s) 2013.

Influence of cardiopulmonary bypass on platelet and neutrophil accumulations in internal organs.

PubMed

Bhujle, R; Li, J; Shastri, P; Gaffke, J N; Clift, J E; Ye, Y W; Dollar, M L; Ching, P; Chao, R; Constantinescu, A; Kulkarni, P V; Cheng, Q C; Wians, F; Jessen, M E; Eberhart, R C

1997-01-01

The authors employed gamma scintigraphy to quantify the post bypass accumulations of platelets and neutrophils in the lung, liver, and heart of adult pigs subjected to a standard 90 min regimen of normothermic cardiopulmonary bypass (CPB). Coated and uncoated microporous polypropylene oxygenator circuits were studied for Cobe Duo (Arvada, CO) oxygenators (amphophilic silicone-caprolactone oligomer [SMA] coating, n = 8 each) and Medtronic Maxima (Irvine, CA) oxygenators (Carmeda heparin coating, n = 5 each). Images of cells in the organs (deposited + blood pool) were corrected for tissue absorption and other factors and compared for a 2 hr period post CPB, using repeat measures ANOVA and rank tests. Platelet accumulations in internal organs correlated positively with whole blood platelet counts and negatively with platelet deposits in oxygenators during CPB. In general, uncoated CPB circuits significantly reduced platelet and neutrophil accumulations in lung, liver, and heart versus preCPB controls for the post CPB interval, for both systems. The SMA treatment significantly increased platelet accumulations versus uncoated controls in lung, liver, and heart for the 2 hr period, including the majority of the post CPB sampling intervals; platelet densities did not reach preCPB levels. Neutrophil accumulations were unaffected by the SMA coating. Carmeda heparin treatment significantly increased platelet accumulations in the liver, but not lung or heart. Despite preservation of circulating neutrophils observed with the Carmeda heparin treatment, neutrophil accumulations in internal organs were not elevated post CPB.

Dynamics of Productivity-Related Oxygen Minimum Zone along the Shirshov Ridge, Western Bering Sea, during the Last Glacial Termination

NASA Astrophysics Data System (ADS)

Ovsepyan, E.; Ivanova, E. V.; Tiedemann, R.

2017-12-01

Seasonally sea-ice covered Bering Sea is known to be a sensitive region to study rapid climatic oscillations. Based on benthic (BF) and planktic (PF) foraminiferal data from two sediment cores SO201-2-85KL (85KL, w.d. 968 m) and SO201-2-77KL (77KL, w.d. 2163 m) we reconstruct variations in intensity of oxygen minimum zone (OMZ) and its relation to sea-surface bioproductivity in the central and southern parts of the Shirshov Ridge, western Bering Sea, during the Termination I. A prevalence of suboxic BF group (Kaiho, 1994) in both cores mirrors moderately oxygenated intermediate and deep waters during LGM-Heinrich I interval. Rapid increase in percentages of dysoxic group is registered in the core 77KL at the onset of Bølling/Allerød. This implies that relatively low-oxygen conditions developed at 2 km water depths in the southwestern Bering Sea, but occurrence (20-30%) of suboxic group suggests that oxygen depletion was not dramatic. Simultaneous spikes of high-productivity species point to a bioproductivity rise above the southern part of the ridge. Increase in bioproductivity and decrease in oxygen content are detected 0.9 kyr later above the central part of Shirshov Ridge than above the southern one. This delay might reflect a gradual sea ice retreat from station 77 KL to 85KL during the global warming and sea level rise. Moderate bottom-water oxygenation is suggested for the intermediate depths of 1 km whereas no changes in relative oxygen content are found at 2 km below sea level during the Younger Dryas. Concurrent decrease in bioproductivity is reconstructed from BF records from the core 85KL. However, presence of high-productivity species and elevated BF accumulation rates in the core 77KL point to higher organic matter flux to the sea floor in the southern part of the ridge at the end of Younger Dryas. For the Early Holocene, bioproductivity rise and oxygen depletion in the intermediate waters are inferred from BF data. Strong dominance of dysoxic group in the 85KL indicates that oxygen content at the intermediate depths was much lower during the Early Holocene than during the Bølling/Allerød. The results provide evidence for complex development of OMZ in the western Bering Sea during the Termination I. They also demonstrate high potential to extend such studies to the North Pacific realm.

Elevated concentrations of nonesterified fatty acids increase monocyte expression of CD11b and adhesion to endothelial cells.

PubMed

Zhang, Wei-Yang; Schwartz, Eric; Wang, Yingjie; Attrep, Jeanne; Li, Zhi; Reaven, Peter

2006-03-01

Monocyte proinflammatory activity has been demonstrated in obesity, insulin resistance, and type 2 diabetes, metabolic conditions that are frequently associated with elevated levels of nonesterified fatty acids (NEFA). We therefore tested the hypothesis that NEFA may induce monocyte inflammation. Monocytes exposed to NEFA for 2 days demonstrated a dose-related increase in intracellular reactive oxygen species (ROS) formation and adhesion to endothelial cells. All of these effects were inhibited by the coaddition of antioxidants such as glutathione or butylated hydroxytoluene, by inhibition of ROS generation by NADPH oxidase inhibitors, and by inhibition of protein kinase C, a recognized stimulator of NAPDH oxidase. Monocytes exposed to NEFA also demonstrated a significant increase in CD11b message expression. Stimulation of monocyte adhesion to endothelial cells by NEFA was inhibited by addition of neutralizing antibodies to either CD11b or CD18. Finally, surface expression of CD11b increased significantly on monocytes as measured by flow cytometry, after their incubation with NEFA. These studies indicate that elevated concentrations of NEFA may enhance integrin facilitated monocyte adhesion to endothelial cells and these effects appear mediated, in part, through activation of NADPH oxidase and oxidative stress.

Effects of ocean acidification on immune responses of the Pacific oyster Crassostrea gigas.

PubMed

Wang, Qing; Cao, Ruiwen; Ning, Xuanxuan; You, Liping; Mu, Changkao; Wang, Chunlin; Wei, Lei; Cong, Ming; Wu, Huifeng; Zhao, Jianmin

2016-02-01

Ocean acidification (OA), caused by anthropogenic CO2emissions, has been proposed as one of the greatest threats in marine ecosystems. A growing body of evidence shows that ocean acidification can impact development, survival, growth and physiology of marine calcifiers. In this study, the immune responses of the Pacific oyster Crassostrea gigas were investigated after elevated pCO2 exposure for 28 days. The results demonstrated that OA caused an increase of apoptosis and reactive oxygen species (ROS) production in hemocytes. Moreover, elevated pCO2 had an inhibitory effect on some antioxidant enzyme activities and decreased the GSH level in digestive gland. However, the mRNA expression pattern of several immune related genes varied depending on the exposure time and tissues. After exposure to pCO2 at ∼2000 ppm for 28 days, the mRNA expressions of almost all tested genes were significantly suppressed in gills and stimulated in hemocytes. Above all, our study demonstrated that elevated pCO2 have a significant impact on the immune systems of the Pacific oyster, which may constitute as a potential threat to increased susceptibility of bivalves to diseases. Copyright © 2015 Elsevier Ltd. All rights reserved.

Equivalent air depth: fact or fiction.

PubMed

Berghage, T E; McCraken, T M

1979-12-01

In mixed-gas diving theory, the equivalent air depth (EAD) concept suggests that oxygen does not contribute to the total tissue gas tension and can therefore be disregarded in calculations of the decompression process. The validity of this assumption has been experimentally tested by exposing 365 rats to various partial pressures of oxygen for various lengths of time. If the EAD assumption is correct, under a constant exposure pressure each incremental change in the oxygen partial pressure would produce a corresponding incremental change in pressure reduction tolerance. Results of this study suggest that the EAD concept does not adequately describe the decompression advantages obtained from breathing elevated oxygen partial pressures. The authors suggest that the effects of breathing oxygen vary in a nonlinear fashion across the range from anoxia to oxygen toxicity, and that a simple inert gas replacement concept is no longer tenable.

Thermochemistry of tantalum-wall cooling system with lithium and sodium working fluids

NASA Technical Reports Server (NTRS)

Tower, L. K.

1972-01-01

Plots are presented which show the distribution of oxygen between liquid lithium and tantalum or niobium, and between liquid sodium and tantalum at elevated temperatures. Additional plots showing the composition of the gas phase above the solutions of oxygen and alkali metal are presented. The use of the plots is illustrated by an example tantalum heat pipe filled with lithium.

Tafenoquine, an Antiplasmodial 8-Aminoquinoline, Targets Leishmania Respiratory Complex III and Induces Apoptosis ▿

PubMed Central

Carvalho, Luis; Luque-Ortega, Juan Román; Manzano, José Ignacio; Castanys, Santiago; Rivas, Luis; Gamarro, Francisco

2010-01-01

Tafenoquine (TFQ), an 8-aminoquinoline analogue of primaquine, which is currently under clinical trial (phase IIb/III) for the treatment and prevention of malaria, may represent an alternative treatment for leishmaniasis. In this work, we have studied the mechanism of action of TFQ against Leishmania parasites. TFQ impaired the overall bioenergetic metabolism of Leishmania promastigotes, causing a rapid drop in intracellular ATP levels without affecting plasma membrane permeability. TFQ induced mitochondrial dysfunction through the inhibition of cytochrome c reductase (respiratory complex III) with a decrease in the oxygen consumption rate and depolarization of mitochondrial membrane potential. This was accompanied by ROS production, elevation of intracellular Ca2+ levels and concomitant nuclear DNA fragmentation. We conclude that TFQ targets Leishmania mitochondria, leading to an apoptosis-like death process. PMID:20837758

Tafenoquine, an antiplasmodial 8-aminoquinoline, targets leishmania respiratory complex III and induces apoptosis.

PubMed

Carvalho, Luis; Luque-Ortega, Juan Román; Manzano, José Ignacio; Castanys, Santiago; Rivas, Luis; Gamarro, Francisco

2010-12-01

Tafenoquine (TFQ), an 8-aminoquinoline analogue of primaquine, which is currently under clinical trial (phase IIb/III) for the treatment and prevention of malaria, may represent an alternative treatment for leishmaniasis. In this work, we have studied the mechanism of action of TFQ against Leishmania parasites. TFQ impaired the overall bioenergetic metabolism of Leishmania promastigotes, causing a rapid drop in intracellular ATP levels without affecting plasma membrane permeability. TFQ induced mitochondrial dysfunction through the inhibition of cytochrome c reductase (respiratory complex III) with a decrease in the oxygen consumption rate and depolarization of mitochondrial membrane potential. This was accompanied by ROS production, elevation of intracellular Ca(2+) levels and concomitant nuclear DNA fragmentation. We conclude that TFQ targets Leishmania mitochondria, leading to an apoptosis-like death process.

A mitochondrial redox oxygen sensor in the pulmonary vasculature and ductus arteriosus.

PubMed

Dunham-Snary, Kimberly J; Hong, Zhigang G; Xiong, Ping Y; Del Paggio, Joseph C; Herr, Julia E; Johri, Amer M; Archer, Stephen L

2016-01-01

The mammalian homeostatic oxygen sensing system (HOSS) initiates changes in vascular tone, respiration, and neurosecretion that optimize oxygen uptake and tissue oxygen delivery within seconds of detecting altered environmental or arterial PO2. The HOSS includes carotid body type 1 cells, adrenomedullary cells, neuroepithelial bodies, and smooth muscle cells (SMCs) in pulmonary arteries (PAs), ductus arteriosus (DA), and fetoplacental arteries. Hypoxic pulmonary vasoconstriction (HPV) optimizes ventilation-perfusion matching. In utero, HPV diverts placentally oxygenated blood from the non-ventilated lung through the DA. At birth, increased alveolar and arterial oxygen tension dilates the pulmonary vasculature and constricts the DA, respectively, thereby transitioning the newborn to an air-breathing organism. Though modulated by endothelial-derived relaxing and constricting factors, O2 sensing is intrinsic to PASMCs and DASMCs. Within the SMC's dynamic mitochondrial network, changes in PO2 alter the reduction-oxidation state of redox couples (NAD(+)/NADH, NADP(+)/NADPH) and the production of reactive oxygen species, ROS (e.g., H2O2), by complexes I and III of the electron transport chain (ETC). ROS and redox couples regulate ion channels, transporters, and enzymes, changing intracellular calcium [Ca(2+)]i and calcium sensitivity and eliciting homeostatic responses to hypoxia. In PASMCs, hypoxia inhibits ROS production and reduces redox couples, thereby inhibiting O2-sensitive voltage-gated potassium (Kv) channels, depolarizing the plasma membrane, activating voltage-gated calcium channels (CaL), increasing [Ca(2+)]i, and causing vasoconstriction. In DASMCs, elevated PO2 causes mitochondrial fission, increasing ETC complex I activity and ROS production. The DASMC's downstream response to elevated PO2 (Kv channel inhibition, CaL activation, increased [Ca(2+)]i, and rho kinase activation) is similar to the PASMC's hypoxic response. Impaired O2 sensing contributes to human diseases, including pulmonary arterial hypertension and patent DA.

Remodeling of Aorta Extracellular Matrix as a Result of Transient High Oxygen Exposure in Newborn Rats: Implication for Arterial Rigidity and Hypertension Risk

PubMed Central

Castro, Michele M.; Cloutier, Anik; Bertagnolli, Mariane; Sartelet, Hervé; Germain, Nathalie; Comte, Blandine; Schulz, Richard; DeBlois, Denis; Nuyt, Anne Monique

2014-01-01

Neonatal high-oxygen exposure leads to elevated blood pressure, microvascular rarefaction, vascular dysfunction and arterial (aorta) rigidity in adult rats. Whether structural changes are present in the matrix of aorta wall is unknown. Considering that elastin synthesis peaks in late fetal life in humans, and early postnatal life in rodents, we postulated that transient neonatal high-oxygen exposure can trigger premature vascular remodelling. Sprague Dawley rat pups were exposed from days 3 to 10 after birth to 80% oxygen (vs. room air control) and were studied at 4 weeks. Blood pressure and vasomotor response of the aorta to angiotensin II and to the acetylcholine analogue carbachol were not different between groups. Vascular superoxide anion production was similar between groups. There was no difference between groups in aortic cross sectional area, smooth muscle cell number or media/lumen ratio. In oxygen-exposed rats, aorta elastin/collagen content ratio was significantly decreased, the expression of elastinolytic cathepsin S was increased whereas collagenolytic cathepsin K was decreased. By immunofluorescence we observed an increase in MMP-2 and TIMP-1 staining in aortas of oxygen-exposed rats whereas TIMP-2 staining was reduced, indicating a shift in the balance towards degradation of the extra-cellular matrix and increased deposition of collagen. There was no significant difference in MMP-2 activity between groups as determined by gelatin zymography. Overall, these findings indicate that transient neonatal high oxygen exposure leads to vascular wall alterations (decreased elastin/collagen ratio and a shift in the balance towards increased deposition of collagen) which are associated with increased rigidity. Importantly, these changes are present prior to the elevation of blood pressure and vascular dysfunction in this model, and may therefore be contributory. PMID:24743169

Simulation of hydrodynamics, temperature, and dissolved oxygen in Table Rock Lake, Missouri, 1996-1997

USGS Publications Warehouse

Green, W. Reed; Galloway, Joel M.; Richards, Joseph M.; Wesolowski, Edwin A.

2003-01-01

Outflow from Table Rock Lake and other White River reservoirs support a cold-water trout fishery of substantial economic yield in south-central Missouri and north-central Arkansas. The Missouri Department of Conservation has requested an increase in existing minimum flows through the Table Rock Lake Dam from the U.S. Army Corps of Engineers to increase the quality of fishable waters downstream in Lake Taneycomo. Information is needed to assess the effect of increased minimum flows on temperature and dissolved- oxygen concentrations of reservoir water and the outflow. A two-dimensional, laterally averaged, hydrodynamic, temperature, and dissolved-oxygen model, CE-QUAL-W2, was developed and calibrated for Table Rock Lake, located in Missouri, north of the Arkansas-Missouri State line. The model simulates water-surface elevation, heat transport, and dissolved-oxygen dynamics. The model was developed to assess the effects of proposed increases in minimum flow from about 4.4 cubic meters per second (the existing minimum flow) to 11.3 cubic meters per second (the increased minimum flow). Simulations included assessing the effect of (1) increased minimum flows and (2) increased minimum flows with increased water-surface elevations in Table Rock Lake, on outflow temperatures and dissolved-oxygen concentrations. In both minimum flow scenarios, water temperature appeared to stay the same or increase slightly (less than 0.37 ?C) and dissolved oxygen appeared to decrease slightly (less than 0.78 mg/L) in the outflow during the thermal stratification season. However, differences between the minimum flow scenarios for water temperature and dissolved- oxygen concentration and the calibrated model were similar to the differences between measured and simulated water-column profile values.

The formation of a subsurface anticyclonic eddy in the Peru-Chile Undercurrent and its impact on the near-coastal salinity, oxygen, and nutrient distributions

NASA Astrophysics Data System (ADS)

Thomsen, Soeren; Kanzow, Torsten; Krahmann, Gerd; Greatbatch, Richard J.; Dengler, Marcus; Lavik, Gaute

2016-01-01

The formation of a subsurface anticyclonic eddy in the Peru-Chile Undercurrent (PCUC) in January and February 2013 is investigated using a multiplatform four-dimensional observational approach. Research vessel, multiple glider, and mooring-based measurements were conducted in the Peruvian upwelling regime near 12°30'S. The data set consists of >10,000 glider profiles and repeated vessel-based hydrography and velocity transects. It allows a detailed description of the eddy formation and its impact on the near-coastal salinity, oxygen, and nutrient distributions. In early January, a strong PCUC with maximum poleward velocities of ˜0.25 m/s at 100-200 m depth was observed. Starting on 20 January, a subsurface anticyclonic eddy developed in the PCUC downstream of a topographic bend, suggesting flow separation as the eddy formation mechanism. The eddy core waters exhibited oxygen concentration of <1 μmol/kg, an elevated nitrogen deficit of ˜17 μmol/L, and potential vorticity close to zero, which seemed to originate from the bottom boundary layer of the continental slope. The eddy-induced across-shelf velocities resulted in an elevated exchange of water masses between the upper continental slope and the open ocean. Small-scale salinity and oxygen structures were formed by along-isopycnal stirring, and indications of eddy-driven oxygen ventilation of the upper oxygen minimum zone were observed. It is concluded that mesoscale stirring of solutes and the offshore transport of eddy core properties could provide an important coastal open ocean exchange mechanism with potentially large implications for nutrient budgets and biogeochemical cycling in the oxygen minimum zone off Peru.

Spectral reflectance of the ocular fundus as a diagnostic marker for cerebral malaria

NASA Astrophysics Data System (ADS)

Liu, Xun; Rice, David A.; Khoobehi, Bahram

2012-03-01

The challenge of correctly identifying malaria infection continues to impede our efforts to control this disease. Recent studies report highly specific retinal changes in severe malaria patients; these retinal changes may represent a very useful diagnostic indicator for this disease. To further explore the ocular manifestations of malaria, we used hyperspectral imaging to study retinal changes caused by Plasmodium berghei ANKA parasitization in a mouse model. We collected the spectral reflectance of the ocular fundus from hyperspectral images of the mouse eye. The blood oxygen sensitive spectral region was normalized for variances in illumination, and used to calculate relative values that correspond to oxygenated hemoglobin levels. Oxygen hemoglobin levels are markedly lower in parasitized mice, indicating that hemoglobin digestion by P. berghei may be detected using spectral reflectance. Furthermore, the ocular reflectance of parasitized mice was abnormally elevated between 660nm and 750nm, suggesting fluorescence in this region. While the source of this fluorescence is not yet clear, its presence correlates strongly with P. Berghei parasitization, and may indicate the presence of hemozoin deposits in the retinal vasculature. The pathology of severe malaria still presents many questions for clinicians and scientists, and our understanding of cerebral malaria has been generally confined to clinical observation and postmortem examination. As the retina represents a portion of the central nervous system that can be easily examined noninvasively, our technique may provide the basis for an automated tool to detect and examine severe malaria via retinal changes.

Genetic and Metabolite Diversity of Sardinian Populations of Helichrysum italicum

PubMed Central

Melito, Sara; Sias, Angela; Petretto, Giacomo L.; Chessa, Mario; Pintore, Giorgio; Porceddu, Andrea

2013-01-01

Background Helichrysum italicum (Asteraceae) is a small shrub endemic to the Mediterranean Basin, growing in fragmented and diverse habitats. The species has attracted attention due to its secondary metabolite content, but little effort has as yet been dedicated to assessing the genetic and metabolite diversity present in these populations. Here, we describe the diversity of 50 H. italicum populations collected from a range of habitats in Sardinia. Methods H. italicum plants were AFLP fingerprinted and the composition of their leaf essential oil characterized by GC-MS. The relationships between the genetic structure of the populations, soil, habitat and climatic variables and the essential oil chemotypes present were evaluated using Bayesian clustering, contingency analyses and AMOVA. Key results The Sardinian germplasm could be partitioned into two AFLP-based clades. Populations collected from the southwestern region constituted a homogeneous group which remained virtually intact even at high levels of K. The second, much larger clade was more diverse. A positive correlation between genetic diversity and elevation suggested the action of natural purifying selection. Four main classes of compounds were identified among the essential oils, namely monoterpenes, oxygenated monoterpenes, sesquiterpenes and oxygenated sesquiterpenes. Oxygenated monoterpene levels were significantly correlated with the AFLP-based clade structure, suggesting a correspondence between gene pool and chemical diversity. Conclusions The results suggest an association between chemotype, genetic diversity and collection location which is relevant for the planning of future collections aimed at identifying valuable sources of essential oil. PMID:24260149

Optimal ventilatory patterns in periodic breathing.

PubMed

Ghazanshahi, S D; Khoo, M C

1993-01-01

The goal of this study was to determine whether periodic breathing (PB), which is highly prevalent during sleep at high altitudes, imposes physiological penalties on the respiratory system in the absence of any accompanying disease. Using a computer model of respiratory gas exchange, we compared the effects of a variety of PB patterns on the chemical and mechanical costs of breathing to those resulting from regular tidal breathing. Although PB produced considerable fluctuation in arterial blood gas tensions, for the same cycle-averaged ventilation, higher arterial oxygen saturation and lower arterial carbon dioxide levels were achieved. This result can be explained by the fact that the combination of large breaths and apnea in PB leads to a substantial reduction in dead space ventilation. At the same time, the savings in mechanical cost achieved by the respiratory muscles during apnea partially offset the increase during the breathing phase. Consequently, the "pressure cost," a criterion based on mean inspiratory pressure, was elevated only slightly, although the average work rate of breathing increased significantly. We found that, at extreme altitudes, PB patterns with clusters of 2 to 4 large breaths that alternate with apnea produce the highest arterial oxygenation levels and lowest pressure costs. The common occurrence of PB patterns with closely similar features has been reported in sleeping healthy sojourners at extreme altitudes. Taken together, these findings suggest that PB favors a reduction in the oxygen demands of the respiratory muscles and therefore may not be as detrimental as it is generally believed to be.

Consumption of flavanol-rich cocoa acutely increases microcirculation in human skin.

PubMed

Neukam, Karin; Stahl, Wilhelm; Tronnier, Hagen; Sies, Helmut; Heinrich, Ulrike

2007-02-01

Long term cocoa ingestion leads to an increased resistance against UV-induced erythema and a lowered transepidermal water loss. To investigate the acute effects of a single dose of cocoa rich in flavanols on dermal microcirculation. In a crossover design study, 10 healthy women ingested a cocoa drink (100 ml) with high (329 mg) or low (27 mg) content of flavanols. The major flavanol monomer in both drinks was epicatechin, 61 mg in the high flavanol, and 6.6 mg in the low flavanol product per 100 ml. Dermal blood flow and oxygen saturation of hemoglobin were examined by laser Doppler flowmetry and spectroscopically at 1 mm skin depth at t = 0, 1, 2, 4, and 6 h. At the same time points, plasma levels of total epicatechin (free compound plus conjugates) were measured by means of HPLC. Subsequent to the intake of high flavanol cocoa, dermal blood flow was significantly increased by 1.7-fold at t = 2 h and oxygen saturation was elevated 1.8-fold. No statistically significant changes were found upon intake of low flavanol cocoa. Maximum plasma levels of total epicatechin were observed 1 h after ingestion of the high flavanol cocoa drink, 11.6 +/- 7.4 nmol/l at baseline, and 62.9 +/- 35.8 nmol/l at 1 h. No change of total epicatechin was found in the low flavanol group. Flavanol-rich cocoa consumption acutely increases dermal blood flow and oxygen saturation.

Interleukin-6, interleukin-8, and soluble tumor necrosis factor receptor-I in the cord blood as predictors of chronic lung disease in premature infants.

PubMed

An, Hiromi; Nishimaki, Shigeru; Ohyama, Makiko; Haruki, Atsushi; Naruto, Takuya; Kobayashi, Naoki; Sugai, Toshiyuki; Kobayashi, Yoshinori; Mori, Masaaki; Seki, Kazuo; Yokota, Shumpei

2004-11-01

In order to predict the late-development of chronic lung disease of prematurity (CLD), cytokines in the cord blood were assessed in this study. Eighteen premature infants with CLD were enrolled. Cord blood plasma levels of cytokines of these infants and 12 control infants without CLD were measured including interleukin (IL)-1beta, IL-2, IL-4, IL-6, IL-8, IL-10, interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha, soluble TNF receptor-I, and soluble IL-6 receptor using a cytometric bead array and an enzyme-linked immunosorbent assay. The cord blood IL-6, IL-8, and sTNFR-I levels were significantly elevated in CLD infants compared with those in control (P < .05). IL-1beta, IL-2, IL-4, IL-10, and IFN-gamma were undetectable in both groups. CLD infants with maternal chorioamnionitis had higher IL-6 than those without chorioamnionitis (P < .01). In CLD infants, IL-6 was higher in the infants who required prolonged oxygen therapy (P < .05). Elevated inflammatory cytokines in the cord blood are associated with the progression to CLD.

Puerarin protects against lead-induced cytotoxicity in cultured primary rat proximal tubular cells.

PubMed

Liu, Gang; Li, Zifa; Wang, Jinqiu; Wang, Hong; Wang, Zhenyong; Wang, Lin

2014-10-01

Puerarin, a potent free radicals scavenger, has been demonstrated to have protective efficacy in oxidative damage induced by nephrotoxins. In the present study, the attenuating effect of puerarin (PU) on lead (Pb)-induced apoptosis and oxidative stress was investigated in cultured primary rat proximal tubular (rPT) cells. Results showed that exposure to 0.5 µM Pb induced a decrease in cell viability accompanied with obvious cellular morphological alterations and caused an increase in apoptotic rate and apoptotic morphological changes. Simultaneously, depletion of mitochondrial membrane potential (ΔΨ) and intracellular glutathione (GSH); elevation of caspase-3 activity, intracellular reactive oxygen species, and malondialdehyde levels; and inhibition of GSH peroxidase (GSH-Px) activity were revealed in the cells exposed to Pb alone. However, simultaneous supplementation with PU (50 and 100 µM) protected rPT cells from Pb-induced cytotoxicity through inhibiting apoptosis, attenuating lipid peroxidation, renewing mitochondrial function, and elevating the intracellular antioxidants (nonenzymatic and enzymic) levels. In conclusion, these findings suggested that PU, as a widely distributed dietary antioxidant, contributes potentially to inhibition of Pb-induced cytotoxicity in rPT cells. © The Author(s) 2014.

Marked over expression of uncoupling protein-2 in beta cells exerts minor effects on mitochondrial metabolism

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hals, Ingrid K., E-mail: ingrid.hals@ntnu.no; Ogata, Hirotaka; Pettersen, Elin

2012-06-29

Highlights: Black-Right-Pointing-Pointer The impact of UCP-2 over expression on mitochondrial function is controversial. Black-Right-Pointing-Pointer We tested mitochondrial functions at defined levels of overexpression. Black-Right-Pointing-Pointer We find minor increases of fatty acid oxidation and uncoupling. Black-Right-Pointing-Pointer Effects were seen only at high level (fourfold) of over expression. Black-Right-Pointing-Pointer Hence it is doubtful whether these effects are of importance in diabetes. -- Abstract: Evidence is conflicting as to the impact of elevated levels of uncoupling protein-2 (UCP-2) on insulin-producing beta cells. Here we investigated effects of a fourfold induction of UCP-2 protein primarily on mitochondrial parameters and tested for replication of positivemore » findings at a lower level of induction. We transfected INS-1 cells to obtain a tet-on inducible cell line. A 48 h exposure to 1 {mu}g/ml of doxycycline (dox) induced UCP-2 fourfold (424 {+-} 113%, mean {+-} SEM) and 0.1 {mu}g/ml twofold (178 {+-} 29%, n = 3). Fourfold induced cells displayed normal viability (MTT, apoptosis), normal cellular insulin contents and, glucose-induced insulin secretion (+27 {+-} 11%) as well as D-[U-{sup 14}C]-glucose oxidation (+5 {+-} 9% at 11 mM glucose). Oxidation of [1-{sup 14}C]-oleate was increased from 4088 to 5797 fmol/{mu}g prot/2 h at 3.3 mM glucose, p < 0.03. Oxidation of L-[{sup 14}C(U)]-glutamine was unaffected. Induction of UCP-2 did not significantly affect measures of mitochondrial membrane potential (Rhodamine 123) or mitochondrial mass (Mitotracker Green) and did not affect ATP levels. Oligomycin-inhibited oxygen consumption (a measure of mitochondrial uncoupling) was marginally increased, the effect being significant in comparison with dox-only treated cells, p < 0.05. Oxygen radicals, assessed by dichlorofluorescin diacetate, were decreased by 30%, p < 0.025. Testing for the lower level of UCP-2 induction did not reproduce any of the positive findings. A fourfold induction of UCP-2 was required to exert minor metabolic effects. These findings question an impact of moderately elevated UCP-2 levels in beta cells as seen in diabetes.« less

Oxidative Lung Damage Resulting from Repeated Exposure to Radiation and Hyperoxia Associated with Space Exploration.

PubMed

Pietrofesa, Ralph A; Turowski, Jason B; Arguiri, Evguenia; Milovanova, Tatyana N; Solomides, Charalambos C; Thom, Stephen R; Christofidou-Solomidou, Melpo

2013-09-30

Spaceflight missions may require crewmembers to conduct Extravehicular Activities (EVA) for repair, maintenance or scientific purposes. Pre-breathe protocols in preparation for an EVA entail 100% hyperoxia exposure that may last for a few hours (5-8 hours), and may be repeated 2-3 times weekly. Each EVA is associated with additional challenges such as low levels of total body cosmic/galactic radiation exposure that may present a threat to crewmember health and therefore, pose a threat to the success of the mission. We have developed a murine model of combined, hyperoxia and radiation exposure (double-hit) in the context of evaluating countermeasures to oxidative lung damage associated with space flight. In the current study, our objective was to characterize the early and chronic effects of repeated single and double-hit challenge on lung tissue using a novel murine model of repeated exposure to low-level total body radiation and hyperoxia. This is the first study of its kind evaluating lung damage relevant to space exploration in a rodent model. Mouse cohorts (n=5-15/group) were exposed to repeated: a) normoxia; b) >95% O 2 (O 2 ); c) 0.25Gy single fraction gamma radiation (IR); or d) a combination of O 2 and IR (O 2 +IR) given 3 times per week for 4 weeks. Lungs were evaluated for oxidative damage, active TGFβ1 levels, cell apoptosis, inflammation, injury, and fibrosis at 1, 2, 4, 8, 12, 16, and 20 weeks post-initiation of exposure. Mouse cohorts exposed to all challenge conditions displayed decreased bodyweight compared to untreated controls at 4 and 8 weeks post-challenge initiation. Chronic oxidative lung damage to lipids (malondialdehyde levels), DNA (TUNEL, cleaved Caspase 3, cleaved PARP positivity) leading to apoptotic cell death and to proteins (nitrotyrosine levels) was elevated all treatment groups. Importantly, significant systemic oxidative stress was also noted at the late phase in mouse plasma, BAL fluid, and urine. Importantly, however, late oxidative damage across all parameters that we measured was significantly higher than controls in all cohorts but was exacerbated by the combined exposure to O 2 and IR. Additionally, impaired levels of arterial blood oxygenation were noted in all exposure cohorts. Significant but transient elevation of lung tissue fibrosis ( p <0.05), determined by lung hydroxyproline content, was detected as early as 2 week in mice exposed to challenge conditions and persisted for 4-8 weeks only. Interestingly, active TGFβ1 levels in +BAL fluid was also transiently elevated during the exposure time only (1-4 weeks). Inflammation and lung edema/lung injury was also significantly elevated in all groups at both early and late time points, especially the double-hit group. We have characterized significant, early and chronic lung changes consistent with oxidative tissue damage in our murine model of repeated radiation and hyperoxia exposure relevant to space travel. Lung tissue changes, detectable several months after the original exposure, include significant oxidative lung damage (lipid peroxidation, DNA damage and protein nitrosative stress) and increased pulmonary fibrosis. These findings, along with increased oxidative stress in diverse body fluids and the observed decreases in blood oxygenation levels in all challenge conditions (whether single or in combination), lead us to conclude that in our model of repeated exposure to oxidative stressors, chronic tissue changes are detected that persist even months after the exposure to the stressor has ended. This data will provide useful information in the design of countermeasures to tissue oxidative damage associated with space exploration.

Oxidative Lung Damage Resulting from Repeated Exposure to Radiation and Hyperoxia Associated with Space Exploration

PubMed Central

Pietrofesa, Ralph A; Turowski, Jason B; Arguiri, Evguenia; Milovanova, Tatyana N; Solomides, Charalambos C; Thom, Stephen R; Christofidou-Solomidou, Melpo

2013-01-01

Background Spaceflight missions may require crewmembers to conduct Extravehicular Activities (EVA) for repair, maintenance or scientific purposes. Pre-breathe protocols in preparation for an EVA entail 100% hyperoxia exposure that may last for a few hours (5-8 hours), and may be repeated 2-3 times weekly. Each EVA is associated with additional challenges such as low levels of total body cosmic/galactic radiation exposure that may present a threat to crewmember health and therefore, pose a threat to the success of the mission. We have developed a murine model of combined, hyperoxia and radiation exposure (double-hit) in the context of evaluating countermeasures to oxidative lung damage associated with space flight. In the current study, our objective was to characterize the early and chronic effects of repeated single and double-hit challenge on lung tissue using a novel murine model of repeated exposure to low-level total body radiation and hyperoxia. This is the first study of its kind evaluating lung damage relevant to space exploration in a rodent model. Methods Mouse cohorts (n=5-15/group) were exposed to repeated: a) normoxia; b) >95% O2 (O2); c) 0.25Gy single fraction gamma radiation (IR); or d) a combination of O2 and IR (O2+IR) given 3 times per week for 4 weeks. Lungs were evaluated for oxidative damage, active TGFβ1 levels, cell apoptosis, inflammation, injury, and fibrosis at 1, 2, 4, 8, 12, 16, and 20 weeks post-initiation of exposure. Results Mouse cohorts exposed to all challenge conditions displayed decreased bodyweight compared to untreated controls at 4 and 8 weeks post-challenge initiation. Chronic oxidative lung damage to lipids (malondialdehyde levels), DNA (TUNEL, cleaved Caspase 3, cleaved PARP positivity) leading to apoptotic cell death and to proteins (nitrotyrosine levels) was elevated all treatment groups. Importantly, significant systemic oxidative stress was also noted at the late phase in mouse plasma, BAL fluid, and urine. Importantly, however, late oxidative damage across all parameters that we measured was significantly higher than controls in all cohorts but was exacerbated by the combined exposure to O2 and IR. Additionally, impaired levels of arterial blood oxygenation were noted in all exposure cohorts. Significant but transient elevation of lung tissue fibrosis (p<0.05), determined by lung hydroxyproline content, was detected as early as 2 week in mice exposed to challenge conditions and persisted for 4-8 weeks only. Interestingly, active TGFβ1 levels in +BAL fluid was also transiently elevated during the exposure time only (1-4 weeks). Inflammation and lung edema/lung injury was also significantly elevated in all groups at both early and late time points, especially the double-hit group. Conclusion We have characterized significant, early and chronic lung changes consistent with oxidative tissue damage in our murine model of repeated radiation and hyperoxia exposure relevant to space travel. Lung tissue changes, detectable several months after the original exposure, include significant oxidative lung damage (lipid peroxidation, DNA damage and protein nitrosative stress) and increased pulmonary fibrosis. These findings, along with increased oxidative stress in diverse body fluids and the observed decreases in blood oxygenation levels in all challenge conditions (whether single or in combination), lead us to conclude that in our model of repeated exposure to oxidative stressors, chronic tissue changes are detected that persist even months after the exposure to the stressor has ended. This data will provide useful information in the design of countermeasures to tissue oxidative damage associated with space exploration. PMID:24358450

Thermal analysis and kinetics of coal during oxy-fuel combustion

NASA Astrophysics Data System (ADS)

Kosowska-Golachowska, Monika

2017-08-01

The pyrolysis and oxy-fuel combustion characteristics of Polish bituminous coal were studied using non-isothermal thermogravimetric analysis. Pyrolysis tests showed that the mass loss profiles were almost similar up to 870°C in both N2 and CO2 atmospheres, while further mass loss occurred in CO2 atmosphere at higher temperatures due to char-CO2 gasification. Replacement of N2 in the combustion environment by CO2 delayed the combustion of bituminous coal. At elevated oxygen levels, TG/DTG profiles shifted through lower temperature zone, ignition and burnout temperatures decreased and mass loss rate significantly increased and complete combustion was achieved at lower temperatures and shorter times. Kinetic analysis for the tested coal was performed using Kissinger-Akahira-Sunose (KAS) method. The activation energies of bituminous coal combustion at the similar oxygen content in oxy-fuel with that of air were higher than that in air atmosphere. The results indicated that, with O2 concentration increasing, the activation energies decreased.

[Effect of argon and nitrogen on the peritoneal macrophages in mice and their resistance to the UV damaging effect in vitro].

PubMed

Galchuk, S V; Turovetskiĭ, V B; Andreev, A I; Buravkova, L B

2001-01-01

Explored were effects of argon and nitrogen on intracellular pH in peritoneal macrophages in mice and resistance of cellular membranes to the UV damaging effect in vitro. Blasting argon or nitrogen along the surface of cell cultures in airtight chamber for 20 minutes was shown to decrease 5-folds the oxygen content of solution as compared with initial level with culture pH unchanged. Ten-minute blasting argon or nitrogen through the incubation chamber slightly elevates intracellular pH in macrophages. The standard cell incubation conditions recovered following approximately 60 minutes in hypoxic atmosphere, the ability of macrophages to build up fluorescein was degraded and they increased intracellular pH no matter the indifferent gas yet more marked in case of nitrogen in use. It was demonstrated that the normobaric gas environment with oxygen partly replaced by nitrogen or argon protects plasmatic membranes of cells from UV-induced damage.

Creatine kinase response to high-intensity aerobic exercise in adult-onset muscular dystrophy.

PubMed

Andersen, Søren P; Sveen, Marie-Louise; Hansen, Regitze S; Madsen, Karen L; Hansen, Jonas B; Madsen, Mads; Vissing, John

2013-12-01

We investigated the effect of high-intensity exercise on plasma creatine kinase (CK) in patients with muscular dystrophies. Fourteen patients with Becker (BMD), facioscapulohumeral (FSHD), or limb-girdle type 2 (LGMD2) muscular dystrophy, and 8 healthy subjects performed 5 cycling tests: an incremental max test, and tests at 65%, 75%, 85%, and 95% of maximal oxygen uptake (VO2max ). Heart rate and oxygen consumption were measured during the tests, and plasma CK was measured before, immediately after, and 24 hours after exercise. All subjects were able to perform high-intensity exercise at the different levels. In patients with LGMD2 and FSHD, CK normalized 24 hours after exercise compared with the pre-exercise value, whereas those with BMD and healthy controls had elevated CK values 24 hours after exercise. The findings suggest that high-intensity exercise is generally well tolerated in patients with LGMD2 and FSHD, whereas those with BMD may be more prone to exercise-induced damage. Copyright © 2013 Wiley Periodicals, Inc.

Environmental consequences of the flooding of the Bay Park Sewage Treatment Plant during Superstorm Sandy.

PubMed

Swanson, R Lawrence; Wilson, Robert; Brownawell, Bruce; Willig, Kaitlin

2017-08-15

Failure of the Bay Park Sewage Treatment Plant (STP) during Superstorm Sandy led to adverse effects in the waters of Hempstead Bay, Long Island, NY. These appear to be related to large discharges of partially treated sewage through its primary and auxiliary outfalls. Modeled dilution discharges indicate that sewage infiltrated the bay, remaining up to 10days. Water column impacts included salinity and dissolved oxygen declines, and biological oxygen demand and nitrogen concentration increases. While the STP does not appear to have released fecal coliform, there were elevated levels of enterococci within the bay for a considerable period following the storm, probably from multiple sources. The STP's reduced functioning and associated environmental impacts, even with resilience upgrades, are not conducive to removing the bay from the list of Impaired Water Bodies. The results reinforce the need to transfer the discharge from the existing outfall to the ocean. Copyright © 2017 Elsevier Ltd. All rights reserved.

Rare earth nanoparticles prevent retinal degeneration induced by intracellular peroxides:

NASA Astrophysics Data System (ADS)

Chen, Junping; Patil, Swanand; Seal, Sudipta; McGinnis, James F.

2006-11-01

Photoreceptor cells are incessantly bombarded with photons of light, which, along with the cells' high rate of oxygen metabolism, continuously exposes them to elevated levels of toxic reactive oxygen intermediates (ROIs). Vacancy-engineered mixed-valence-state cerium oxide nanoparticles (nanoceria particles) scavenge ROIs. Our data show that nanoceria particles prevent increases in the intracellular concentrations of ROIs in primary cell cultures of rat retina and, in vivo, prevent loss of vision due to light-induced degeneration of photoreceptor cells. These data indicate that the nanoceria particles may be effective in inhibiting the progression of ROI-induced cell death, which is thought to be involved in macular degeneration, retinitis pigmentosa and other blinding diseases, as well as the ROI-induced death of other cell types in diabetes, Alzheimer's disease, atherosclerosis, stroke and so on. The use of nanoceria particles as a direct therapy for multiple diseases represents a novel strategy and suggests that they may represent a unique platform technology.

REE compositions in fossil vertebrate dental tissues indicate biomineral preservation

NASA Astrophysics Data System (ADS)

Žigaite, Ž.; Kear, B.; Pérez-Huerta, A.; Jeffries, T.; Blom, H.

2012-04-01

Rare earth element (REE) abundances have been measured in a number of Palaeozoic and Mesozoic dental tissues using Laser Ablation Inductively Coupled Plasma Mass-spectrometry (LA-ICP-MS). Fossil vertebrates analysed comprise scales and tesserae of Silurian and Devonian acanthodians, chondrichthyans, galeaspids, mongolepids, thelodonts, as well as teeth of Cretaceous lungfish and marine reptiles. The evaluation of fossil preservation level has been made by semi-quantitative spot geochemistry analyses on fine polished teeth and scale thin sections, using Energy Dispersive X-ray Spectroscopy (EDS). Fossil teeth and scales with significant structure and colour alteration have shown elevated heavy element concentrations, and the silicification of bioapatite has been common in their tissues. Stable oxygen isotope measurements (δ18O) of bulk biomineral have been conducted in parallel, and showed comparatively lower heavy oxygen values in the same fossil tissues with stronger visible alteration. Significant difference in REE concentrations has been observed between the dentine and enamel of Cretaceous plesiosaurs, suggesting the enamel to be more geochemically resistant to diagenetic overprint.

Effect of supplemental oxygen on post-exercise inflammatory response and oxidative stress.

PubMed

White, Jodii; Dawson, Brian; Landers, Grant; Croft, Kevin; Peeling, Peter

2013-04-01

This investigation explored the influence of supplemental oxygen administered during the recovery periods of an interval-based running session on the post-exercise markers of reactive oxygen species (ROS) and inflammation. Ten well-trained male endurance athletes completed two sessions of 10 × 3 min running intervals at 85 % of the maximal oxygen consumption velocity (vVO(2)peak) on a motorised treadmill. A 90-s recovery period was given between each interval, during which time the participants were administered either a hyperoxic (HYP) (Fraction of Inspired Oxygen (FIO2) 99.5 %) or normoxic (NORM) (FIO2 21 %) gas, in a randomized, single-blind fashion. Pulse oximetry (SpO(2)), heart rate (HR), blood lactate (BLa), perceived exertion (RPE), and perceived recovery (TQRper) were recorded during each trial. Venous blood samples were taken pre-exercise, post-exercise and 1 h post-exercise to measure Interleukin-6 (IL-6) and Isoprostanes (F2-IsoP). The S(p)O(2) was significantly lower than baseline following all interval repetitions in both experimental trials (p < 0.05). The S(p)O(2) recovery time was significantly quicker in the HYP when compared to the NORM (p < 0.05), with a trend for improved perceptual recovery. The IL-6 and F2-IsoP were significantly elevated immediately post-exercise, but had significantly decreased by 1 h post-exercise in both trials (p < 0.05). There were no differences in IL-6 or F2-IsoP levels between trials. Supplemental oxygen provided during the recovery periods of interval based exercise improves the recovery time of SPO(2) but has no effect on post-exercise ROS or inflammatory responses.

Oxidation-Induced Degradable Nanogels for Iron Chelation

NASA Astrophysics Data System (ADS)

Liu, Zhi; Wang, Yan; Purro, Max; Xiong, May P.

2016-02-01

Iron overload can increase cellular oxidative stress levels due to formation of reactive oxygen species (ROS); untreated, it can be extremely destructive to organs and fatal to patients. Since elevated oxidative stress levels are inherent to the condition in such patients, oxidation-induced degradable nanogels for iron chelation were rationally designed by simultaneously polymerizing oxidation-sensitive host-guest crosslinkers between β-cyclodextrin (β-CD) and ferrocene (Fc) and iron chelating moieties composed of deferoxamine (DFO) into the final gel scaffold in reverse emulsion reaction chambers. UV-Vis absorption and atomic absorption spectroscopy (AAS) was used to verify iron chelating capability of nanogels. These materials can degrade into smaller chelating fragments at rates proportional to the level of oxidative stress present. Conjugating DFO reduces the cytotoxicity of the chelator in the macrophage cells. Importantly, the nanogel can effectively reduce cellular ferritin expression in iron overloaded cells and regulate intracellular iron levels at the same time, which is important for maintaining a homeostatic level of this critical metal in cells.

Oxidation-Induced Degradable Nanogels for Iron Chelation

PubMed Central

Liu, Zhi; Wang, Yan; Purro, Max; Xiong, May P.

2016-01-01

Iron overload can increase cellular oxidative stress levels due to formation of reactive oxygen species (ROS); untreated, it can be extremely destructive to organs and fatal to patients. Since elevated oxidative stress levels are inherent to the condition in such patients, oxidation-induced degradable nanogels for iron chelation were rationally designed by simultaneously polymerizing oxidation-sensitive host-guest crosslinkers between β-cyclodextrin (β-CD) and ferrocene (Fc) and iron chelating moieties composed of deferoxamine (DFO) into the final gel scaffold in reverse emulsion reaction chambers. UV-Vis absorption and atomic absorption spectroscopy (AAS) was used to verify iron chelating capability of nanogels. These materials can degrade into smaller chelating fragments at rates proportional to the level of oxidative stress present. Conjugating DFO reduces the cytotoxicity of the chelator in the macrophage cells. Importantly, the nanogel can effectively reduce cellular ferritin expression in iron overloaded cells and regulate intracellular iron levels at the same time, which is important for maintaining a homeostatic level of this critical metal in cells. PMID:26868174

The effect of interstitial pressure on tumor growth: coupling with the blood and lymphatic vascular systems

PubMed Central

Wu, Min; Frieboes, Hermann B.; McDougall, Steven R.; Chaplain, Mark A.J.; Cristini, Vittorio; Lowengrub, John

2013-01-01

The flow of interstitial fluid and the associated interstitial fluid pressure (IFP) in solid tumors and surrounding host tissues have been identified as critical elements in cancer growth and vascularization. Both experimental and theoretical studies have shown that tumors may present elevated IFP, which can be a formidable physical barrier for delivery of cell nutrients and small molecules into the tumor. Elevated IFP may also exacerbate gradients of biochemical signals such as angiogenic factors released by tumors into the surrounding tissues. These studies have helped to understand both biochemical signaling and treatment prognosis. Building upon previous work, here we develop a vascular tumor growth model by coupling a continuous growth model with a discrete angiogenesis model. We include fluid/oxygen extravasation as well as a continuous lymphatic field, and study the micro-environmental fluid dynamics and their effect on tumor growth by accounting for blood flow, transcapillary fluid flux, interstitial fluid flow, and lymphatic drainage. We thus elucidate further the non-trivial relationship between the key elements contributing to the effects of interstitial pressure in solid tumors. In particular, we study the effect of IFP on oxygen extravasation and show that small blood/lymphatic vessel resistance and collapse may contribute to lower transcapillary fluid/oxygen flux, thus decreasing the rate of tumor growth. We also investigate the effect of tumor vascular pathologies, including elevated vascular and interstitial hydraulic conductivities inside the tumor as well as diminished osmotic pressure differences, on the fluid flow across the tumor capillary bed, the lymphatic drainage, and the IFP. Our results reveal that elevated interstitial hydraulic conductivity together with poor lymphatic function is the root cause of the development of plateau profiles of the IFP in the tumor, which have been observed in experiments, and contributes to a more uniform distribution of oxygen, solid tumor pressure and a broad-based collapse of the tumor lymphatics. We also find that the rate that IFF is fluxed into the lymphatics and host tissue is largely controlled by an elevated vascular hydraulic conductivity in the tumor. We discuss the implications of these results on microenvironmental transport barriers, and the tumor invasive and metastatic potential. Our results suggest the possibility of developing strategies of targeting tumor cells based on the cues in the interstitial fluid. PMID:23220211

Different Effects of Oral Contraceptive and Dydrogesterone Treatment on Oxidative Stress Levels in Premenopausal Women

PubMed Central

Chen, Jui-Tung; Kotani, Kazuhiko

2018-01-01

Background The aim of the study was to observe the changes in blood oxidative stress levels by oral contraceptive (OC) and/or dydrogesterone (DG) treatment. Methods A retrospective cohort of 27 premenopausal women with primary dysmenorrhea consisted of the OC treatment group (N = 17) and the DG treatment group (N = 10) by choice of the initial treatment. The OC group included two subgroups: patients with continuous OC treatment (treated for at least 15 months, N = 10) and patients with discontinuous OC treatment (switched to DG treatment after approximately 6 months of initial OC treatment: N = 7). The DG group had 15 months of continuous DG treatment. Blood parameters, including diacron-reactive oxygen metabolites (d-ROMs: an oxidative stress marker), were measured. Results The d-ROMs level was elevated in the OC group 3 months after initial treatment (mean: from 321 (at baseline) to 512 Carratelli Units (Carr U); P < 0.01), while such changes were not observed in the DG group. The d-ROMs level was reduced in the discontinuous OC subgroup 15 months after initial treatment (from 508 (3 months after initial treatment) to 372 Carr U; P < 0.01), while such changes were not observed in the continuous OC subgroup. The DG group displayed unchanged the d-ROMs level. Conclusion Replacing OC with DG can attenuate oxidative stress as elevated by OC, thereby alleviating the possible vascular risks with OC treatment. PMID:29317960

Ribose in the heart.

PubMed

Herrick, James; St Cyr, John

2008-01-01

Every cell needs energy, i.e., adenosine triphosphate (ATP), to carry out its function. Decreased oxygen levels, decreased blood flow, and other stressful conditions can drastically effect the intracellular concentrations of these energy compounds. Skeletal muscle, unlike the heart, can address this drop in ATP by employing the myokinase reaction, ultimately producing ATP with a subsequent elevation in adenosine monophosphate (AMP). Ribose, a naturally occurring 5-carbon monosaccharide, is a key component of RNA, DNA (which has deoxyribose), acetyl coenzyme A, and ATP. Each cell produces its own ribose, involved in the pentose phosphate pathway (PPP), to aid in ATP production. States of ischemia and/or hypoxia can severely lower levels of cellular energy compounds in the heart, with an associated compromise in cellular processes, ultimately reflected in altered function. Ribose appears to provide a solution to the problem in replenishing the depressed ATP levels and improving functional status of patients afflicted with cardiovascular diseases.

Trace elemental correlation study in malignant and normal breast tissue by PIXE technique

NASA Astrophysics Data System (ADS)

Raju, G. J. Naga; Sarita, P.; Kumar, M. Ravi; Murty, G. A. V. Ramana; Reddy, B. Seetharami; Lakshminarayana, S.; Vijayan, V.; Lakshmi, P. V. B. Rama; Gavarasana, Satyanarayana; Reddy, S. Bhuloka

2006-06-01

Particle induced X-ray emission technique was used to study the variations in trace elemental concentrations between normal and malignant human breast tissue specimens and to understand the effects of altered homeostasis of these elements in the etiology of breast cancer. A 3 MeV proton beam was used to excite the biological samples of normal and malignant breast tissues. The elements Cl, K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, Zn, As, Se, Br, Rb and Sr were identified and their relative concentrations were estimated. Almost all the elements were found to be elevated (p < 0.05, Wilcoxon signed-ranks test) in the cancerous tissues when compared with normal tissues. The excess levels of trace elements observed in the cancerous breast tissues could either be a cause or a consequence of breast cancer. Regarding their role in the initiation or promotion of breast cancer, one possible interpretation is that the elevated levels of Cu, Fe and Cr could have led to the formation of free radicals or other reactive oxygen species (ROS) that adversely affect DNA thereby causing breast cancer, which is mainly attributed to genetic abnormalities. Moreover, since Cu and Fe are required for angiogenesis, elevated concentrations of these elements are likely to promote breast cancer by increasing the blood supply for tumor growth. On the other hand elevated concentrations of elements in breast cancer tissues might also be a consequence of the cancer. This can be understood in terms of the biochemical and histological differences between normal and cancerous breast tissues. Tumors, characterized by unregulated multiplication of cells, need an ever-increasing supply of essential nutrients including trace elements. This probably results in an increased vascularity of malignant tissues, which in turn leads to enhancement of elemental concentrations in tumors.

In vivo photoacoustic imaging of chorioretinal oxygen gradients

NASA Astrophysics Data System (ADS)

Hariri, Ali; Wang, Junxin; Kim, Yeji; Jhunjhunwala, Anamik; Chao, Daniel L.; Jokerst, Jesse V.

2018-03-01

Chorioretinal imaging has a crucial role for the patients with chorioretinal vascular diseases, such as neovascular age-related macular degeneration. Imaging oxygen gradients in the eye could better diagnose and treat ocular diseases. Here, we describe the use of photoacoustic ocular imaging (PAOI) in measuring chorioretinal oxygen saturation (CR - sO2) gradients in New Zealand white rabbits (n = 5) with ocular ischemia. We observed good correlation (R2 = 0.98) between pulse oximetry and PAOI as a function of different oxygen percentages in inhaled air. We then used an established ocular ischemia model in which intraocular pressure is elevated to constrict ocular blood flow, and notice a positive correlation (R2 = 0.92) between the injected volume of phosphate buffered saline (PBS) and intraocular pressure (IOP) as well as a negative correlation (R2 = 0.98) between CR - sO2 and injected volume of PBS. The CR - sO2 was measured before (baseline), during (ischemia), and after the infusion (600-μL PBS). The ischemia-reperfusion model did not affect the measurement of the sO2 using a pulse oximeter on the animal's paw, but the chorioretinal PAOI signal showed a nearly sixfold decrease in CR - sO2 (n = 5, p = 0.00001). We also observe a sixfold decrease in CR - sO2 after significant elevation of IOP during ischemia, with an increase close to baseline during reperfusion. These data suggest that PAOI can detect changes in chorioretinal oxygenation and may be useful for application to imaging oxygen gradients in ocular disease.

Altered respiratory responses to hypoxia in mutant mice deficient in neuronal nitric oxide synthase

PubMed Central

Kline, David D; Yang, Tianen; Huang, Paul L; Prabhakar, Nanduri R

1998-01-01

The role of endogenous nitric oxide (NO) generated by neuronal nitric oxide synthase (NOS-1) in the control of respiration during hypoxia and hypercapnia was assessed using mutant mice deficient in NOS-1. Experiments were performed on awake and anaesthetized mutant and wild-type control mice. Respiratory responses to varying levels of inspired oxygen (100, 21 and 12 % O2) and carbon dioxide (3 and 5 % CO2 balanced oxygen) were analysed. In awake animals, respiration was monitored by body plethysmograph along with oxygen consumption (V̇O2), CO2 production (V̇CO2) and body temperature. In anaesthetized, spontaneously breathing mice, integrated efferent phrenic nerve activity was monitored as an index of neural respiration along with arterial blood pressure and blood gases. Cyclic 3′,5′-guanosine monophosphate (cGMP) levels in the brainstem were analysed by radioimmunoassay as an index of nitric oxide generation. Unanaesthetized mutant mice exhibited greater respiratory responses during 21 and 12 % O2 than the wild-type controls. Respiratory responses were associated with significant decreases in oxygen consumption in both groups of mice, and the magnitude of change was greater in mutant than wild-type mice. Changes in CO2 production and body temperature, however, were comparable between both groups of mice. Similar augmentation of respiratory responses during hypoxia was also observed in anaesthetized mutant mice. In addition, five of the fourteen mutant mice displayed periodic oscillations in respiration (brief episodes of increases in respiratory rate and tidal phrenic nerve activity) while breathing 21 and 12 % O2, but not during 100 % O2. The time interval between the episodes decreased by reducing inspired oxygen from 21 to 12 % O2. Changes in arterial blood pressure and arterial blood gases were comparable at any given level of inspired oxygen between both groups of mice, indicating that changes in these variables do not account for the differences in the response to hypoxia. Respiratory responses to brief hyperoxia (Dejours test) and to cyanide, a potent chemoreceptor stimulant, were more pronounced in mutant mice, suggesting augmented peripheral chemoreceptor sensitivity. cGMP levels were elevated in the brainstem during 21 and 12 % O2 in wild-type but not in mutant mice, indicating decreased formation of nitric oxide in mutant mice. The magnitude of respiratory responses to hypercapnia (3 and 5 % CO2 balanced oxygen) was comparable in both groups of mice in the awake and anaesthetized conditions. These observations suggest that the hypoxic responses were selectively augmented in mutant mice deficient in NOS-1. Peripheral as well as central mechanisms contributed to the altered responses to hypoxia. These results support the idea that nitric oxide generated by NOS-1 is an important physiological modulator of respiration during hypoxia. PMID:9679181

Physiological response of the cold-water coral Desmophyllum dianthus to thermal stress and ocean acidification.

PubMed

Gori, Andrea; Ferrier-Pagès, Christine; Hennige, Sebastian J; Murray, Fiona; Rottier, Cécile; Wicks, Laura C; Roberts, J Murray

2016-01-01

Rising temperatures and ocean acidification driven by anthropogenic carbon emissions threaten both tropical and temperate corals. However, the synergistic effect of these stressors on coral physiology is still poorly understood, in particular for cold-water corals. This study assessed changes in key physiological parameters (calcification, respiration and ammonium excretion) of the widespread cold-water coral Desmophyllum dianthus maintained for ∼8 months at two temperatures (ambient 12 °C and elevated 15 °C) and two pCO2 conditions (ambient 390 ppm and elevated 750 ppm). At ambient temperatures no change in instantaneous calcification, respiration or ammonium excretion rates was observed at either pCO2 levels. Conversely, elevated temperature (15 °C) significantly reduced calcification rates, and combined elevated temperature and pCO2 significantly reduced respiration rates. Changes in the ratio of respired oxygen to excreted nitrogen (O:N), which provides information on the main sources of energy being metabolized, indicated a shift from mixed use of protein and carbohydrate/lipid as metabolic substrates under control conditions, to less efficient protein-dominated catabolism under both stressors. Overall, this study shows that the physiology of D. dianthus is more sensitive to thermal than pCO2 stress, and that the predicted combination of rising temperatures and ocean acidification in the coming decades may severely impact this cold-water coral species.

Arsenic occurrence, mobility, and retardation in sandstone and dolomite formations of the Fox River Valley, Eastern Wisconsin.

PubMed

Thornburg, Katie; Sahai, Nita

2004-10-01

Elevated levels of groundwater arsenic (approximately 100 microg L(-1) = 1.3 x 10(-6) M) are found in the Fox River Valley, eastern Wisconsin. The goals of this study were to identifythe sources of As contamination and to determine the reactions responsible for As mobilization and retardation in areas lacking a discrete zone of As-enriched sulfides, shown previouslyto cause elevated arsenic in groundwater. Detailed mineralogical and chemical analyses were conducted on samples from the Sinnipee Group dolomite and St. Peter sandstone in eastern Wisconsin. Solution chemistry was monitored in batch reactions of dolomite, quartz, and sulfide mineral fractions with a 0.01 M CsCl solution at pH 7 for 3 weeks in air. Results indicate that arsenic is present in isomorphous substitution with pyrite/marcasite (FeS2), which occurs as disseminated veins, grains, and nodules in the dolomite and sandstone. The released As subsequently sorbs on the ferric oxyhydroxides formed or coprecipitates in a scorodite-like phase. Significantly, oxidative dissolution of the disseminated As-rich FeS2 grains and nodules is sufficient to explain the elevated As levels observed in eastern Wisconsin groundwater. Although complete uptake of As is observed in the batch experiments, persistent elevated As levels with spatial and temporal variations in regional groundwaters are attributed to differences in the type of sulfide occurrence (discrete horizon vs dispersed grains, veins, and nodules), variations in the dissolved oxygen content of the groundwater, and variable (limited) buildup of reacted surface layers on sulfide grains in the natural flow-through system. Discrete nanoparticulate As phases, As surface precipitates on sulfides, and sorbed As on dolomite and quartz are eliminated as major sources, and sorption of arsenic on dolomite and quartz is deemed less important than association with ferric oxyhydroxides for retardation in the regional system.

Copper modified carbon molecular sieves for selective oxygen removal

NASA Technical Reports Server (NTRS)

Sharma, Pramod K. (Inventor); Seshan, Panchalam K. (Inventor)

1992-01-01

Carbon molecular sieves modified by the incorporation of finely divided elemental copper useful for the selective sorption of oxygen at elevated temperatures. The carbon molecular sieves can be regenerated by reduction with hydrogen. The copper modified carbon molecular sieves are prepared by pyrolysis of a mixture of a copper-containing material and polyfunctional alcohol to form a sorbent precursor. The sorbent precursors are then heated and reduced to produce copper modified carbon molecular sieves. The copper modified carbon molecular sieves are useful for sorption of all concentrations of oxygen at temperatures up to about 200.degree. C. They are also useful for removal of trace amount of oxygen from gases at temperatures up to about 600.degree. C.

Impact of oxidative stress on exercising skeletal muscle.

PubMed

Steinbacher, Peter; Eckl, Peter

2015-04-10

It is well established that muscle contractions during exercise lead to elevated levels of reactive oxygen species (ROS) in skeletal muscle. These highly reactive molecules have many deleterious effects, such as a reduction of force generation and increased muscle atrophy. Since the discovery of exercise-induced oxidative stress several decades ago, evidence has accumulated that ROS produced during exercise also have positive effects by influencing cellular processes that lead to increased expression of antioxidants. These molecules are particularly elevated in regularly exercising muscle to prevent the negative effects of ROS by neutralizing the free radicals. In addition, ROS also seem to be involved in the exercise-induced adaptation of the muscle phenotype. This review provides an overview of the evidences to date on the effects of ROS in exercising muscle. These aspects include the sources of ROS, their positive and negative cellular effects, the role of antioxidants, and the present evidence on ROS-dependent adaptations of muscle cells in response to physical exercise.

Metabolic engineering for improved production of ethanol by Corynebacterium glutamicum.

PubMed

Jojima, Toru; Noburyu, Ryoji; Sasaki, Miho; Tajima, Takahisa; Suda, Masako; Yukawa, Hideaki; Inui, Masayuki

2015-02-01

Recombinant Corynebacterium glutamicum harboring genes for pyruvate decarboxylase (pdc) and alcohol dehydrogenase (adhB) can produce ethanol under oxygen deprivation. We investigated the effects of elevating the expression levels of glycolytic genes, as well as pdc and adhB, on ethanol production. Overexpression of four glycolytic genes (pgi, pfkA, gapA, and pyk) in C. glutamicum significantly increased the rate of ethanol production. Overexpression of tpi, encoding triosephosphate isomerase, further enhanced productivity. Elevated expression of pdc and adhB increased ethanol yield, but not the rate of production. Fed-batch fermentation using an optimized strain resulted in ethanol production of 119 g/L from 245 g/L glucose with a yield of 95% of the theoretical maximum. Further metabolic engineering, including integration of the genes for xylose and arabinose metabolism, enabled consumption of glucose, xylose, and arabinose, and ethanol production (83 g/L) at a yield of 90 %. This study demonstrated that C. glutamicum has significant potential for the production of cellulosic ethanol.

High affinity hemoglobin and Parkinson's disease.

PubMed

Graham, Jeffrey; Hobson, Douglas; Ponnampalam, Arjuna

2014-12-01

Parkinson's disease (PD) is a neurodegenerative disorder characterized by the loss of dopaminergic neurons in the substantia nigra (SN) region of the midbrain. Oxidative damage in this region has been shown to play an important role in the pathogenesis of this disease. Human neurons have been discovered to contain hemoglobin, with an increased concentration seen in the neurons of the SN. High affinity hemoglobin is a clinical entity resulting from mutations that create a functional increase in the binding of hemoglobin to oxygen and an inability to efficiently unload it to tissues. This can result in a number of metabolic compensatory changes, including an elevation in circulating hemoglobin and an increase in the molecule 2,3-diphosphoglycerate (2,3-DPG). Population based studies have revealed that patients with PD have elevated hemoglobin as well as 2,3-DPG levels. Based on these observations, we hypothesize that the oxidative damage seen in PD is related to an underlying high affinity hemoglobin subtype. Copyright © 2014 Elsevier Ltd. All rights reserved.

Oxidative stress tolerance in intertidal red seaweed Hypnea musciformis (Wulfen) in relation to environmental components.

PubMed

Maharana, Dusmant; Das, Priya Brata; Verlecar, Xivanand N; Pise, Navnath M; Gauns, Manguesh

2015-12-01

Oxidative stress parameters in relation to temperature and other factors have been analysed in Hypnea musciformis, the red seaweed from Anjuna beach, Goa, with an aim to understand its susceptibility to the changing seasons. The results indicate that elevated temperature, sunshine and dessication during peak summer in May enhanced the activity of lipid peroxide, hydrogen peroxide and antioxidants such as catalase, glutathione and ascorbic acid. Statistical tests using multivariate analysis of variance and correlation analysis showed that oxidative stress and antioxidants maintain significant relation with temperature, salinity, sunshine and pH at an individual or interactive level. The dissolved nitrates, phosphates and biological oxygen demand in ambient waters and the trace metals in seaweeds maintained sufficiently low values to provide any indication that could exert contaminant oxidative stress responses. The present field studies suggest that elevated antioxidant content in H. musciformis offer sufficient relief to sustain against harsh environmental stresses for its colonization in the rocky intertidal zone.

Hemoglobin Affinity for Oxygen in the Anginal Syndrome with Normal Coronary Arteriograms

PubMed Central

Vokonas, Pantel S.; Cohn, Peter F.; Klein, Michael D.; Laver, Myron B.; Gorlin, Richard

1974-01-01

Oxyhemoglobin dissociation (OHD) curves were performed on whole blood (WB) from 20 patients with anginal pain, normal hemodynamics, and normal coronary arteries, as demonstrated by selective coronary cinearteriography. OHD curves in 19 of 20 patients, from zero to full saturation, were nearly identical to those in normal control subjects with values for P50 (Po2 at 50% saturation and pH 7.4) of 26.7±1.5 (mean±SD of the mean) torr (mm Hg) and red blood cell (RBC) levels of 2,3-diphosphoglyceric acid (2, 3-DPG) of 0.72±0.10 (mean±SD of the mean) M/M hemoglobin (Hb). Normal values for nonsmoking adults were: P50, 26.6±1.4 (mean±SD of the mean) torr: and RBC 2,3-DPG, 0.81±0.09 (mean±SD of the mean) M/M Hb. Mean levels of carbon monoxide were normal at 0.14±0.01 (mean±SEM) ml/100 ml WB in 10 patients who were nonsmokers and 0.45±0.15 (mean±SEM) ml/100 ml WB in 10 smokers. In one patient, a heavy smoker with markedly elevated blood carbon monoxide levels, an abnormal leftward shift of the OHD curve was observed. This was corrected after discontinuation of smoking. In utilizing these methods, we could not detect consistent abnormalities of Hb affinity for oxygen at rest in the patients studied, which suggests that a defect in oxygen transport at rest is an unlikely explanation for the symptoms of chest pain in patients with the anginal syndrome and normal coronary arteriograms. Images PMID:4847250

Response of benthic foraminifera to phytodetritus in the eastern Arabian Sea under low oxygen conditions

NASA Astrophysics Data System (ADS)

Enge, Annekatrin; Wukovits, Julia; Wanek, Wolfgang; Watzka, Margarete; Witte, Ursula; Hunter, William; Heinz, Petra

2016-04-01

At water depths between 100 and 1500 m a permanent Oxygen Minimum Zone (OMZ) impinges on the sea floor in the eastern Arabian Sea, exposing benthic organisms to anoxic to suboxic conditions. The flux of organic matter to the sea floor is relatively high at these depths but displays seasonal variation. Deposition of relatively fresh phytodetrital material (phytoplankton remains) can occur within a short period of time after monsoon periods. Several organism groups including foraminifera are involved to different extent in the processing of phytodetritus in the OMZs of the northern Arabian Sea. A series of in situ feeding experiments were performed to study the short-term processing (< 11 days) of organic carbon, nitrogen and nutritional demands of foraminifera at different oxygen concentrations on the continental margin in the eastern Arabian Sea. For the experiments, a single pulse of isotopically labeled phytodetritus was added to the sediment along a depth transect (540-1100 m) on the Indian Margin, covering the OMZ core and the lower OMZ boundary region. Uptake of phytodetritus within 4 days shows the relevance of phytodetritus as food source for foraminifera. Lower content of phytodetrital carbon recorded in foraminifera from more oxygenated depths shows greater food uptake by foraminifera in the OMZ core than in the OMZ boundary region. The foraminiferal assemblage living under almost anoxic conditions in the OMZ core is dominated by species typically found in eutroph environments (such as Uvigerinids) that are adapted to high flux of organic matter. The elevated carbon uptake can also result from missing food competition by macrofauna or from greater energy demand in foraminifera to sustain metabolic processes under hypoxic stress. Variable levels and ratios of phytodetrital carbon and nitrogen indicate specific nutritional demands and storage of food-derived nitrogen in some foraminifera species under near anoxia where the mean phytodetrital nitrogen content in foraminifera was elevated. In summary, foraminifera dominate the short-term processing of phytodetritus by fauna in the OMZ core but are less important in the lower OMZ boundary region of the Indian margin as a result of biological interactions and changes in the distribution of individual foraminiferal species.

Adrenal Demedullation and Oxygen Supplementation Independently Increase Glucose-Stimulated Insulin Concentrations in Fetal Sheep With Intrauterine Growth Restriction

PubMed Central

Macko, Antoni R.; Yates, Dustin T.; Chen, Xiaochuan; Shelton, Leslie A.; Kelly, Amy C.; Davis, Melissa A.; Camacho, Leticia E.; Anderson, Miranda J.

2016-01-01

In pregnancies complicated by placental insufficiency and intrauterine growth restriction (IUGR), fetal glucose and oxygen concentrations are reduced, whereas plasma norepinephrine and epinephrine concentrations are elevated throughout the final third of gestation. Here we study the effects of chronic hypoxemia and hypercatecholaminemia on β-cell function in fetal sheep with placental insufficiency-induced IUGR that is produced by maternal hyperthermia. IUGR and control fetuses underwent a sham (intact) or bilateral adrenal demedullation (AD) surgical procedure at 0.65 gestation. As expected, AD-IUGR fetuses had lower norepinephrine concentrations than intact-IUGR fetuses despite being hypoxemic and hypoglycemic. Placental insufficiency reduced fetal weights, but the severity of IUGR was less with AD. Although basal plasma insulin concentrations were lower in intact-IUGR and AD-IUGR fetuses compared with intact-controls, glucose-stimulated insulin concentrations were greater in AD-IUGR fetuses compared with intact-IUGR fetuses. Interestingly, AD-controls had lower glucose- and arginine-stimulated insulin concentrations than intact-controls, but AD-IUGR and AD-control insulin responses were not different. To investigate chronic hypoxemia in the IUGR fetus, arterial oxygen tension was increased to normal levels by increasing the maternal inspired oxygen fraction. Oxygenation of IUGR fetuses enhanced glucose-stimulated insulin concentrations 3.3-fold in intact-IUGR and 1.7-fold in AD-IUGR fetuses but did not lower norepinephrine and epinephrine concentrations. Together these findings show that chronic hypoxemia and hypercatecholaminemia have distinct but complementary roles in the suppression of β-cell responsiveness in IUGR fetuses. PMID:26937714

Oxygen- and NssR-dependent Globin Expression and Enhanced Iron Acquisition in the Response of Campylobacter to Nitrosative Stress*S⃞

PubMed Central

Monk, Claire E.; Pearson, Bruce M.; Mulholland, Francis; Smith, Holly K.; Poole, Robert K.

2008-01-01

Pathogenic bacteria experience nitrosative stress from NO generated in the host and from nitrosating species such as S-nitrosoglutathione. The food-borne pathogen Campylobacter jejuni responds by activating gene expression from a small regulon under the control of the NO-sensitive regulator, NssR. Here, we describe the full extent of the S-nitrosoglutathione response using transcriptomic and proteomic analysis of batch- and chemostat-cultured C. jejuni. In addition to the NssR regulon, which includes two hemoglobins (Cgb and Ctb), we identify more than 90 other up-regulated genes, notably those encoding heat shock proteins and proteins involved in oxidative stress tolerance and iron metabolism/transport. Up-regulation of a subset of these genes, including cgb, is also elicited by NO-releasing compounds. Mutation of the iron-responsive regulator Fur results in insensitivity of growth to NO, suggesting that derepression of iron-regulated genes and augmentation of iron acquisition is a physiological response to nitrosative damage. We describe the effect of oxygen availability on nitrosative stress tolerance; cells cultured at higher rates of oxygen diffusion have elevated levels of hemoglobins, are more resistant to inhibition by NO of both growth and respiration, and consume NO more rapidly. The oxygen response is mediated by NssR. Thus, in addition to NO detoxification catalyzed by the hemoglobins Cgb and possibly Ctb, C. jejuni mounts an extensive stress response. We suggest that inhibition of respiration by NO may increase availability of oxygen for Cgb synthesis and function. PMID:18682395

Ammonium excretion and oxygen respiration of tropical copepods and euphausiids exposed to oxygen minimum zone conditions

NASA Astrophysics Data System (ADS)

Kiko, R.; Hauss, H.; Buchholz, F.; Melzner, F.

2015-10-01

Calanoid copepods and euphausiids are key components of marine zooplankton communities worldwide. Most euphausiids and several copepod species perform diel vertical migrations (DVMs) that contribute to the export of particulate and dissolved matter to midwater depths. In vast areas of the global ocean, and in particular in the eastern tropical Atlantic and Pacific, the daytime distribution depth of many migrating organisms corresponds to the core of the oxygen minimum zone (OMZ). At depth, the animals experience reduced temperature and oxygen partial pressure (pO2) and an increased carbon dioxide partial pressure (pCO2) compared to their near-surface nighttime habitat. Although it is well known that low oxygen levels can inhibit respiratory activity, the respiration response of tropical copepods and euphausiids to relevant pCO2, pO2 and temperature conditions remains poorly parameterized. Further, the regulation of ammonium excretion at OMZ conditions is generally not well understood. It was recently estimated that DVM-mediated ammonium supply considerably fuels bacterial anaerobic ammonium oxidation - a major loss process for fixed nitrogen in the ocean. These estimates were based on the implicit assumption that hypoxia or anoxia in combination with hypercapnia (elevated pCO2) does not result in a downregulation of ammonium excretion. Here we show that exposure to OMZ conditions can result in strong depression of respiration and ammonium excretion in calanoid copepods and euphausiids from the Eastern Tropical North Atlantic and the Eastern Tropical South Pacific. These physiological responses need to be taken into account when estimating DVM-mediated fluxes of carbon and nitrogen into OMZs.

Capillary transit time heterogeneity and flow-metabolism coupling after traumatic brain injury

PubMed Central

Østergaard, Leif; Engedal, Thorbjørn S; Aamand, Rasmus; Mikkelsen, Ronni; Iversen, Nina K; Anzabi, Maryam; Næss-Schmidt, Erhard T; Drasbek, Kim R; Bay, Vibeke; Blicher, Jakob U; Tietze, Anna; Mikkelsen, Irene K; Hansen, Brian; Jespersen, Sune N; Juul, Niels; Sørensen, Jens CH; Rasmussen, Mads

2014-01-01

Most patients who die after traumatic brain injury (TBI) show evidence of ischemic brain damage. Nevertheless, it has proven difficult to demonstrate cerebral ischemia in TBI patients. After TBI, both global and localized changes in cerebral blood flow (CBF) are observed, depending on the extent of diffuse brain swelling and the size and location of contusions and hematoma. These changes vary considerably over time, with most TBI patients showing reduced CBF during the first 12 hours after injury, then hyperperfusion, and in some patients vasospasms before CBF eventually normalizes. This apparent neurovascular uncoupling has been ascribed to mitochondrial dysfunction, hindered oxygen diffusion into tissue, or microthrombosis. Capillary compression by astrocytic endfeet swelling is observed in biopsies acquired from TBI patients. In animal models, elevated intracranial pressure compresses capillaries, causing redistribution of capillary flows into patterns argued to cause functional shunting of oxygenated blood through the capillary bed. We used a biophysical model of oxygen transport in tissue to examine how capillary flow disturbances may contribute to the profound changes in CBF after TBI. The analysis suggests that elevated capillary transit time heterogeneity can cause critical reductions in oxygen availability in the absence of ‘classic' ischemia. We discuss diagnostic and therapeutic consequences of these predictions. PMID:25052556

SNJ-1945, a calpain inhibitor, protects SH-SY5Y cells against MPP(+) and rotenone.

PubMed

Knaryan, Varduhi H; Samantaray, Supriti; Park, Sookyoung; Azuma, Mitsuyoshi; Inoue, Jun; Banik, Naren L

2014-07-01

Complex pathophysiology of Parkinson's disease involves multiple CNS cell types. Degeneration in spinal cord neurons alongside brain has been shown to be involved in Parkinson's disease and evidenced in experimental parkinsonism. However, the mechanisms of these degenerative pathways are not well understood. To unravel these mechanisms SH-SY5Y neuroblastoma cells were differentiated into dopaminergic and cholinergic phenotypes, respectively, and used as cell culture model following exposure to two parkinsonian neurotoxicants MPP(+) and rotenone. SNJ-1945, a cell-permeable calpain inhibitor was tested for its neuroprotective efficacy. MPP(+) and rotenone dose-dependently elevated the levels of intracellular free Ca(2+) and induced a concomitant rise in the levels of active calpain. SNJ-1945 pre-treatment significantly protected cell viability and preserved cellular morphology following MPP(+) and rotenone exposure. The neurotoxicants elevated the levels of reactive oxygen species more profoundly in SH-SY5Y cells differentiated into dopaminergic phenotype, and this effect could be attenuated with SNJ-1945 pre-treatment. In contrast, significant levels of inflammatory mediators cyclooxygenase-2 (Cox-2 and cleaved p10 fragment of caspase-1) were up-regulated in the cholinergic phenotype, which could be dose-dependently attenuated by the calpain inhibitor. Overall, SNJ-1945 was efficacious against MPP(+) or rotenone-induced reactive oxygen species generation, inflammatory mediators, and proteolysis. A post-treatment regimen of SNJ-1945 was also examined in cells and partial protection was attained with calpain inhibitor administration 1-3 h after exposure to MPP(+) or rotenone. Taken together, these results indicate that calpain inhibition is a valid target for protection against parkinsonian neurotoxicants, and SNJ-1945 is an efficacious calpain inhibitor in this context. SH-SY5Y cells, differentiated as dopaminergic (TH positive) and cholinergic (ChAT positive), were used as in vitro models for Parkinson's disease. MPP+ and rotenone induced up-regulation of calpain, expression, and activity as a common mechanism of neurodegeneration. SNJ-1945, a novel calpain inhibitor, protected both the cell phenotypes against MPP+ and rotenone. © 2013 International Society for Neurochemistry.

Beneficial effect of resveratrol on bovine oocyte maturation and subsequent embryonic development after in vitro fertilization.

PubMed

Wang, Feng; Tian, XiuZhi; Zhang, Lu; He, ChangJiu; Ji, PengYun; Li, Yu; Tan, DunXian; Liu, GuoShi

2014-02-01

To analyze the potential beneficial effects and mechanisms of action of resveratrol on the maturation of bovine oocytes that were incubated in different concentrations of resveratrol (0.1, 1.0, or 10.0 μM) as germinal vesicle-stage oocytes. In vitro prospective study. University research laboratory. Animal models for human studies. In vitro culture in the presence of various concentrations of the antioxidant resveratrol. Parameters of hormone levels, oocyte nuclear maturation, cumulus expansion, levels of intracellular glutathione and reactive oxygen species, embryonic cleavage, blastocyst formation, gene expression associated with mature bovine oocytes and cumulus cells, and level of sirtuin 1 gene expression. Resveratrol statistically significantly increased progesterone secretion and decreased estradiol-17β secretion by cumulus cells. The elevated levels of progesterone activated the Mos/MEK/p42 mitogen-activated protein kinase (MAPK) cascade in the oocytes. At a concentration of 1.0 μM, resveratrol statistically significantly improved cumulus expansion, polar body formation, the (hatched) blastocyst rate, and the mean number of cells/blastocysts. Meanwhile, resveratrol statistically significantly reduced the level of reactive oxygen species (ROS) and increased the level of glutathione (GSH). For the first time, the expression of the sirtuin-1 gene was identified in granulosa cells, cumulus cells, oocytes, and blastocysts. Further studies revealed that resveratrol promoted sirtuin-1 gene expression. Resveratrol promoted bovine oocyte maturation and subsequent post-in vitro fertilization embryonic development by inducing progesterone secretion and an antioxidant effect, probably in a manner dependent on sirtuin-1. Copyright © 2014 American Society for Reproductive Medicine. All rights reserved.

Isometric exercise (image)

MedlinePlus

Isometric exercise works muscles and strengthens bone. Increased muscle mass elevates metabolism, which in turn burns fat. Strength training is also called anaerobic exercise, as opposed to aerobic, because increased oxygen production is not ...

Reactive Oxygen Species-Producing Myeloid Cells Act as a Bone Marrow Niche for Sterile Inflammation-Induced Reactive Granulopoiesis.

PubMed

Zhu, Haiyan; Kwak, Hyun-Jeong; Liu, Peng; Bajrami, Besnik; Xu, Yuanfu; Park, Shin-Young; Nombela-Arrieta, Cesar; Mondal, Subhanjan; Kambara, Hiroto; Yu, Hongbo; Chai, Li; Silberstein, Leslie E; Cheng, Tao; Luo, Hongbo R

2017-04-01

Both microbial infection and sterile inflammation augment bone marrow (BM) neutrophil production, but whether the induced accelerated granulopoiesis is mediated by a common pathway and the nature of such a pathway are poorly defined. We recently established that BM myeloid cell-derived reactive oxygen species (ROS) externally regulate myeloid progenitor proliferation and differentiation in bacteria-elicited emergency granulopoiesis. In this article, we show that BM ROS levels are also elevated during sterile inflammation. Similar to in microbial infection, ROS were mainly generated by the phagocytic NADPH oxidase in Gr1 + myeloid cells. The myeloid cells and their ROS were uniformly distributed in the BM when visualized by multiphoton intravital microscopy, and ROS production was both required and sufficient for sterile inflammation-elicited reactive granulopoiesis. Elevated granulopoiesis was mediated by ROS-induced phosphatase and tensin homolog oxidation and deactivation, leading to upregulated PtdIns(3,4,5)P3 signaling and increased progenitor cell proliferation. Collectively, these results demonstrate that, although infection-induced emergency granulopoiesis and sterile inflammation-elicited reactive granulopoiesis are triggered by different stimuli and are mediated by distinct upstream signals, the pathways converge to NADPH oxidase-dependent ROS production by BM myeloid cells. Thus, BM Gr1 + myeloid cells represent a key hematopoietic niche that supports accelerated granulopoiesis in infective and sterile inflammation. This niche may be an excellent target in various immune-mediated pathologies or immune reconstitution after BM transplantation. Copyright © 2017 by The American Association of Immunologists, Inc.

Reactive oxygen species-producing myeloid cells act as a bone marrow niche for sterile inflammation-induced reactive granulopoiesis

PubMed Central

Zhu, Haiyan; Kwak, Hyun-Jeong; Liu, Peng; Bajrami, Besnik; Xu, Yuanfu; Park, Shin-Young; Nombela-Arrieta, Cesar; Mondal, Subhanjan; Kambara, Hiroto; Yu, Hongbo; Chai, Li; Silberstein, Leslie E.; Cheng, Tao; Luo, Hongbo R.

2017-01-01

Summary Both microbial infection and sterile inflammation augment bone marrow (BM) neutrophil production, but whether the induced accelerated granulopoiesis is mediated by a common pathway and the nature of such a pathway are poorly defined. We recently established that BM myeloid cell-derived reactive oxygen species (ROS) externally regulate myeloid progenitor proliferation and differentiation in bacteria-elicited emergency granulopoiesis. Here we show that BM ROS levels are also elevated during sterile inflammation. Similar to in microbial infection, ROS were mainly generated by the phagocytic NADPH oxidase in Gr1+ myeloid cells. The myeloid cells and their ROS were uniformly distributed in the BM when visualized by multi-photon intravital microscopy, and ROS production was both required and sufficient for sterile inflammation-elicited reactive granulopoiesis. Elevated granulopoiesis was mediated by ROS-induced PTEN oxidation and deactivation leading to upregulated PtdIns(3,4,5)P3 signaling and increased progenitor cell proliferation. Collectively, these results demonstrate that although infection-induced emergency granulopoiesis and sterile inflammation-elicited reactive granulopoiesis are triggered by different stimuli and are mediated by distinct upstream signals, the pathways converge to NADPH oxidase-dependent ROS production by BM myeloid cells. Thus, BM Gr1+ myeloid cells represent a key hematopoietic niche that supports accelerated granulopoiesis in both infective and sterile inflammation. This niche may be an excellent target in various immune-mediated pathologies or immune reconstitution after BM transplantation. PMID:28235862

Role of NADP+-dependent isocitrate dehydrogenase (NADP+-ICDH) on cellular defence against oxidative injury by gamma-rays.

PubMed

Lee, S H; Jo, S H; Lee, S M; Koh, H J; Song, H; Park, J W; Lee, W H; Huh, T L

2004-09-01

To investigate the regulation of NADPH-producing isocitrate dehydrogenase (ICDH) in cytosol (IDPc) and mitochondria (IDPm) upon gamma-ray irradiation, and the roles of IDPc and IDPm in the protection against cellular damage induced by gamma-ray irradiation. Changes of IDPc and IDPm proteins upon gamma-ray irradiation to NIH3T3 cells were analysed by immunoblotting. To increase or decrease the expression of IDPc or IDPm, NIH3T3 cells were stably transfected with mouse IDPc or IDPm cDNA in either the sense or the antisense direction. The transfected cells with either increased or decreased IDPc or IDPm were exposed to gamma-rays, and the levels of reactive oxygen species generation, protein oxidation and lipid peroxidation were measured. Both IDPc and IDPm activities were induced by gamma-ray in NIH3T3 cells. Cells with decreased expression of IDPc or IDPm had elevated reactive oxygen species generation, lipid peroxidation and protein oxidation. Conversely, overproduction of IDPc or IDPm protein partially protected the cells from oxidative damage induced by gamma-ray irradiation. The protective role of IDPc and IDPm against gamma-ray-induced cellular damage can be attributed to elevated NADPH, reducing equivalents needed for recycling reduced glutathione in the cytosol and mitochondria. Thus, a primary biological function of the ICDHs may be production of NADPH, which is a prerequisite for some cellular defence systems against oxidative damage.

Quercetin reverses hypobaric hypoxia-induced hippocampal neurodegeneration and improves memory function in the rat.

PubMed

Prasad, Jyotsna; Baitharu, Iswar; Sharma, Alpesh Kumar; Dutta, Ruma; Prasad, Dipti; Singh, Shashi Bala

2013-12-01

Inadequate oxygen availability at high altitude causes elevated oxidative stress, resulting in hippocampal neurodegeneration and memory impairment. Though oxidative stress is known to be a major cause of neurodegeneration in hypobaric hypoxia, neuroprotective and ameliorative potential of quercetin, a flavonoid with strong antioxidant properties in reversing hypobaric hypoxia-induced memory impairment has not been studied. Four groups of male adult Sprague Dawley rats were exposed to hypobaric hypoxia for 7 days in an animal decompression chamber at an altitude of 7600 meters. Rats were supplemented with quercetin orally by gavage during 7 days of hypoxic exposure. Spatial working memory was assessed by a Morris Water Maze before and after exposure to hypobaric hypoxia. Changes in oxidative stress markers and apoptotic marker caspase 3 expression in hippocampus were assessed. Histological assessment of neurodegeneration was performed by cresyl violet and fluoro Jade B staining. Our results showed that quercetin supplementation during exposure to hypobaric hypoxia decreased reactive oxygen species levels and consequent lipid peroxidation in the hippocampus by elevating antioxidant status and free radical scavenging enzyme system. There was reduction in caspase 3 expression, and decrease in the number of pyknotic and fluoro Jade B-positive neurons in hippocampus after quercetin supplementation during hypoxic exposure. Behavioral studies showed that quercetin reversed the hypobaric hypoxia-induced memory impairment. These findings suggest that quercetin provides neuroprotection to hippocampal neurons during exposure to hypobaric hypoxia through antioxidative and anti-apoptotic mechanisms, and possesses promising therapeutic potential to ameliorate hypoxia-induced memory dysfunction.

A novel biological function of soluble biglycan: Induction of erythropoietin production and polycythemia.

PubMed

Frey, Helena; Moreth, Kristin; Hsieh, Louise Tzung-Harn; Zeng-Brouwers, Jinyang; Rathkolb, Birgit; Fuchs, Helmut; Gailus-Durner, Valérie; Iozzo, Renato V; de Angelis, Martin Hrabě; Schaefer, Liliana

2017-06-01

Secondary polycythemia, a disease characterized by a selective increase in circulating mature erythrocytes, is caused by enhanced erythropoietin (Epo) concentrations triggered by hypoxia-inducible factor-2α (HIF-2α). While mechanisms of hypoxia-dependent stabilization of HIF-2α protein are well established, data regarding oxygen-independent regulation of HIF-2α are sparse. In this study, we generated a novel transgenic mouse model, in which biglycan was constitutively overexpressed and secreted by hepatocytes (BGN Tg ), thereby providing a constant source of biglycan released into the blood stream. We discovered that although the mice were apparently normal, they harbored an increase in mature circulating erythrocytes. In addition to erythrocytosis, the BGN Tg mice showed elevated hemoglobin concentrations, hematocrit values and enhanced total iron binding capacity, revealing a clinical picture of polycythemia. In BGN Tg mice markedly enhanced Epo mRNA expression was observed in the liver and kidney, while elevated Epo protein levels were found in liver, kidney and blood. Mechanistically, we showed that the transgenic animals had an abundance of HIF-2α protein in the liver and kidney. Finally, by transiently overexpressing circulating biglycan in mice deficient in various Toll-like receptors (TLRs), we determined that this novel function of biglycan to promote Epo synthesis was specifically mediated by a selective interaction with TLR2. Thus, we discovered a novel biological pathway of soluble biglycan inducing HIF-2α protein stabilization and Epo production presumably in an oxygen-independent manner, ultimately giving rise to secondary polycythemia.

Galectin-3 in ambulatory patients with heart failure: results from the HF-ACTION study.

PubMed

Felker, G Michael; Fiuzat, Mona; Shaw, Linda K; Clare, Robert; Whellan, David J; Bettari, Luca; Shirolkar, Shailesh C; Donahue, Mark; Kitzman, Dalane W; Zannad, Faiez; Piña, Ileana L; O'Connor, Christopher M

2012-01-01

Galectin-3 is a soluble ß-galactoside-binding lectin released by activated cardiac macrophages. Elevated levels of galectin-3 have been found to be associated with adverse outcomes in patients with heart failure. We evaluated the association between galectin-3 and long-term clinical outcomes in ambulatory heart failure patients enrolled in the HF-ACTION study. HF-ACTION was a randomized, controlled trial of exercise training in patients with chronic heart failure caused by left ventricular systolic dysfunction. Galectin-3 was assessed at baseline in a cohort of 895 HF-ACTION subjects with stored plasma samples available. The association between galectin-3 and clinical outcomes was assessed using a series of Cox proportional hazards models. Higher galectin-3 levels were associated with other measures of heart failure severity, including higher New York Heart Association class, lower systolic blood pressure, higher creatinine, higher amino-terminal proB-type natriuretic peptide (NTproBNP), and lower maximal oxygen consumption. In unadjusted analysis, there was a significant association between elevated galectin-3 levels and hospitalization-free survival (unadjusted hazard ratio, 1.14 per 3-ng/mL increase in galectin-3; P<0.0001). In multivariable modeling, the prognostic impact of galectin-3 was significantly attenuated by the inclusion of other known predictors, and galectin-3 was no longer a significant predictor after the inclusion of NTproBNP. Galectin-3 is elevated in ambulatory heart failure patients and is associated with poor functional capacity and other known measures of heart failure severity. In univariate analysis, galectin-3 was significantly predictive of long-term outcomes, but this association did not persist after adjustment for other predictors, especially NTproBNP. URL: http://www.clinicaltrials.gov. Unique identifier: NCT00047437.

Galectin-3 in Ambulatory Patients with Heart Failure: Results from the HF-ACTION Study

PubMed Central

Felker, G. Michael; Fiuzat, Mona; Shaw, Linda K.; Clare, Robert; Whellan, David J.; Bettari, Luca; Shirolkar, Shailesh C.; Donahue, Mark; Kitzman, Dalane W.; Zannad, Faiez; Piña, Ileana L.; O’Connor, Christopher M.

2011-01-01

Background Galectin-3 is a soluble ß-galactoside-binding lectin released by activated cardiac macrophages. Elevated levels of galectin-3 have been found to be associated with adverse outcomes in patients with heart failure. We evaluated the association between galectin-3 and long-term clinical outcomes in ambulatory heart failure patients enrolled in the HF-ACTION study. Methods and Results HF-ACTION was a randomized controlled trial of exercise training in patients with chronic heart failure due to left ventricular (LV) systolic dysfunction. Galectin-3 was assessed at baseline in a cohort of 895 HF-ACTION subjects with stored plasma samples available. The association between galectin-3 and clinical outcomes was assessed using a series of Cox proportional hazards models. Higher galectin-3 levels were associated with other measures of heart failure severity, including higher NYHA class, lower systolic blood pressure, higher creatinine, higher NTproBNP, and lower maximal oxygen consumption. In unadjusted analysis, there was a significant association between elevated galectin-3 levels and hospitalization-free survival (unadjusted hazard ratio = 1.14 per 3 ng/mL increase in galectin-3, P<0.0001). In multivariable modeling, the prognostic impact of galectin-3 was significantly attenuated by the inclusion of other known predictors and galectin-3 was no longer a significant predictor after the inclusion of NTproBNP. Conclusions Galectin-3 is elevated in ambulatory heart failure patients and is associated with poor functional capacity and other known measures of heart failure severity. In univariate analysis, galectin-3 was significantly predictive of long-term outcomes, but this association did not persist after adjustment for other predictors, especially NTproBNP. PMID:22016505

Effects of chronic elevated ozone concentration on the redox state and fruit yield of red pepper plant Capsicum baccatum.

PubMed

Bortolin, Rafael Calixto; Caregnato, Fernanda Freitas; Divan, Armando Molina; Reginatto, Flávio Henrique; Gelain, Daniel Pens; Moreira, José Cláudio Fonseca

2014-02-01

Ozone (O3) is one of the most harmful air pollutants to crops, contributing to high losses on crop yield. Tropospheric O3 background concentrations have increased since pre-industrial times reaching phytotoxic concentrations in many world regions. Capsicum peppers are the second most traded spice in the world, but few studies concerning the O3 effects in this genus are known. Thereby, the aim of this work was to evaluate the effects of chronic exposure to elevated O3 concentrations in red pepper plant Capsicum baccatum L. var. pendulum with especial considerations on the leaf redox state and fruit yield. Fifteen C. baccatum plants were exposed to O3 in open-top chambers during fruit ripening (62 days) at a mean concentration of 171.6 µg/m(3) from 10:00 am to 4:00 pm. We found that O3 treated plants significantly decreased the amount and the total weight of fruits, which were probably a consequence of the changes on leaf oxidative status induced by ozone exposure. Ozone exposed plants increased the reactive oxygen species (ROS) levels on the leaves, which may be associated with the observed decrease on the activity of enzymatic antioxidant defense system, as well with lower levels of polyphenol and reduced thiol groups. Enhanced ROS production and the direct O3 reaction lead to biomacromolecules damages as seen in the diminished chlorophyll content and in the elevated lipid peroxidation and protein carbonylation levels. Through a correlation analysis it was possible to observe that polyphenols content was more important to protect pepper plants against oxidative damages to lipids than to proteins. © 2013 Published by Elsevier Inc.

Oxygen as a factor in eukaryote evolution - Some effects of low levels of oxygen on Saccharomyces cerevisiae

NASA Technical Reports Server (NTRS)

Jahnke, L.; Klein, H. P.

1979-01-01

A comparative study of the effects of varying levels of oxygen on some of the metabolic functions of the primitive eukaryote, Saccharomyces cerevisiae, has shown that these cells are responsive to very low levels of oxygen: the level of palmitoyl-Co A desaturase was greatly enhanced by only 0.03 vol % oxygen. Similarly, an acetyl-CoA synthetase associated predominantly with anaerobic growth was stimulated by as little as 0.1% oxygen, while an isoenzyme correlated with aerobic growth was maximally active at much higher oxygen levels (greater than 1%). Closely following this latter pattern were three mitochondrial enzymes that attained maximal activity only under atmospheric levels of oxygen.

Alterations of chemical composition, construction cost and payback time in needles of Masson pine (Pinus massoniana L.) trees grown under pollution.

PubMed

Liu, Nan; Guan, Lan-Lan; Sun, Fang-Fang; Wen, Da-Zhi

2014-07-01

Previous studies show that Masson pine (Pinus massoniana L.) stands grown at the industrially-polluted site have experienced unprecedented growth decline, but the causal mechanisms are poorly understood. In this study, to understand the mechanisms of growth decline of Mason pine strands under pollution stresses, we determined the reactive oxygen species levels and chemical composition of the current-year (C) and one-year-old (C + 1) needles, and calculated the needle construction costs (CCmass) of Masson pine trees grown at an industrially-polluted site and an unpolluted remote site. Pine trees grown at the polluted site had significantly higher levels of hydroxyl radical and superoxide anion in their needles than those grown at the unpolluted site, and the former trees eventually exhibited needle early senescence. The contents of lipids, soluble phenolics and lignins in C and C + 1 needles were significantly higher at the polluted site than at the unpolluted site, but the total amounts of non-construction carbohydrates were lower in non-polluted needles than in polluted needles. Elevated levels of the reactive oxygen species and early senescence in polluted needles together led to significant increases in CCmass and a longer payback time. We infer that the lengthened payback time and needle early senescence under pollution stress may reduce the Masson pine tree growth and consequently accelerate tree decline.

The influence of changes in blood flow on the accuracy of pulse oximetry in humans.

PubMed

Vegfors, M; Lindberg, L G; Lennmarken, C

1992-05-01

Oxygen saturation (SpO2) was measured with a pulse oximeter in ten healthy, young men breathing air. A pulse oximeter probe was attached to the second toe and a laser Doppler probe to the first toe of the same foot for measurement of changes in peripheral blood flow. The pulse oximeter and laser Doppler readings were simultaneously compared when the foot was positioned 40 cm (position 1) above heart level, elevated 10 cm (position 2) above heart level and horizontally at heart level (position 3). Using this experimental human model, we achieved various blood flows. The AC and DC optical signals used for determination of oxygen saturation were recorded from the pulse oximeter and analysed. There was a significant increase (P less than 0.05) between position 1 and 3 in blood flow as measured by the laser Doppler flow meter. The corresponding pulse oximeter readings of haemoglobin saturation also increased significantly (P less than 0.05) comparing these two leg positions. Analysing the AC- and DC optical signals, the AC value of infrared light increased considerably, while the AC value of the red light decreased slightly. The DC values of red and infrared light did not change significantly. In summary, when blood flow was decreased, the ratio of red to infrared transmitted light was changed, resulting in a low SpO2 reading.

Reactive oxygen species dynamics in roots of salt sensitive and salt tolerant cultivars of rice.

PubMed

Saini, Shivani; Kaur, Navdeep; Pati, Pratap Kumar

2018-06-01

Salinity stress is one of the major constraints for growth and survival of plants that affects rice productivity worldwide. Hence, in the present study, roots of two contrasting salinity sensitive cultivars, IR64 (IR64, salt sensitive) and Luna Suvarna (LS, salt tolerant) were compared with regard to the levels of reactive oxygen species (ROS) to derive clues for their differential salt stress adaptation mechanisms. In our investigation, the tolerant cultivar exhibited longer primary roots, more lateral roots, higher root number leading to increased root biomass, with respect to IR64. It was observed that LS roots maintained higher level of H 2 O 2 in comparison to IR64. The activities of various enzymes involved in enzymatic antioxidant defense mechanism (SOD, CAT, GPX, DHAR and MDHAR) were found to be greater in LS roots. Further, the higher transcript level accumulation of genes encoding ROS generating (RbohA, RbohD and RbohE) and scavenging enzymes (Fe-SOD, Chloroplastic Cu/Zn-SOD, CAT and DHAR) were noticed in the roots of tolerant cultivar, LS. Moreover, the content of other stress markers such as total protein and proline were also elevated in LS roots. While, the expression of proline biosynthesis gene (P5CS) and proline catabolism gene (PDH) was observed to be lower in LS. Copyright © 2018. Published by Elsevier Inc.

Flow Field Measurements of Methane-Oxygen Turbulent Nonpremixed Flames at High Pressure

NASA Astrophysics Data System (ADS)

Iino, Kimio; Kikkawa, Hoshitaka; Akamatsu, Fumiteru; Katsuki, Masashi

We carried out the flow field measurement of methane-oxygen turbulent nonpremixed flame in non-combusting and combusting situations at high pressures using LDV. The main objectives are to study the influences of combustion on the turbulence structure at high pressures and to provide detailed data on which numerical predictions on such flows can rely. Direct observation and CH* chemiluminescence detection are conducted at high pressures up to 1.0MPa. It was found that the flame length at elevated pressures became constant. From flow field measurements, the following features of flames at elevated pressure were found: (1) the existence of flame suppressed turbulence in the upstream region of the jet and enhanced it in the downstream region with increasing pressure; (2) Turbulence in the flame was more anisotropic than in the corresponding cold jet in all regions of the flow with increasing pressure; (3) Reynolds shear stresses did not change at elevated pressure; (4) Combustion processes had a marked influence on the turbulence macroscale under high pressures, however, the turbulence macroscale was not changed even with the increase in pressure.

A study on the influence of tides on the water table conditions of the shallow coastal aquifers

NASA Astrophysics Data System (ADS)

Singaraja, C.; Chidambaram, S.; Jacob, Noble

2018-03-01

Tidal variation and water level in aquifer is an important function in the coastal environment, this study attempts to find the relationship between water table fluctuation and tides in the shallow coastal aquifers. The study was conducted by selecting three coastal sites and by monitoring the water level for every 2-h interval in 24 h of observation. The study was done during two periods of full moon and new moon along the Cuddalore coastal region of southern part of Tamil Nadu, India. The study shows the relationship between tidal variation, water table fluctuations, dissolved oxygen, and electrical conductivity. An attempt has also been made in this study to approximate the rate of flow of water. Anyhow, the differences are site specific and the angle of inclination of the water table shows a significant relation to the mean sea level, with respect to the distance of the point of observation from the sea and elevation above mean sea level.

Hyperglycaemia does not affect antigen-specific activation and cytolytic killing by CD8+ T cells in vivo.

PubMed

Recino, Asha; Barkan, Kerry; Wong, F Susan; Ladds, Graham; Cooke, Anne; Wallberg, Maja

2017-08-31

Metabolism is of central importance for T cell survival and differentiation. It is well known that T cells cannot function in the absence of glucose, but it is less clear how they respond to excessive levels of glucose. In the present study, we investigated how increasing levels of glucose affect T-cell-mediated immune responses. We examined the effects of increased levels of glucose on CD8 + T-cell behaviour in vitro by assessing activation and cytokine production, as well as oxygen consumption rate (OCR), extracellular acidification rate (ECAR) and intracellular signalling. In addition, we assessed in vivo proliferation, cytokine production and cytolytic activity of cells in chemically induced diabetic C57BL/6 mice. Elevated levels of glucose in in vitro cultures had modest effects on proliferation and cytokine production, while in vivo hyperglycaemia had no effect on CD8 + T-cell proliferation, interferon γ (IFNγ) production or cytolytic killing. © 2017 The Author(s).

Separating the roles of nitrogen and oxygen in high pressure-induced blood-borne microparticle elevations, neutrophil activation, and vascular injury in mice.

PubMed

Yang, Ming; Bhopale, Veena M; Thom, Stephen R

2015-08-01

An elevation in levels of circulating microparticles (MPs) due to high air pressure exposure and the associated inflammatory changes and vascular injury that occur with it may be due to oxidative stress. We hypothesized that these responses arise due to elevated partial pressures of N2 and not because of high-pressure O2. A comparison was made among high-pressure air, normoxic high-pressure N2, and high-pressure O2 in causing an elevation in circulating annexin V-positive MPs, neutrophil activation, and vascular injury by assessing the leakage of high-molecular-weight dextran in a murine model. After mice were exposed for 2 h to 790 kPa air, there were over 3-fold elevations in total circulating MPs as well as subgroups bearing Ly6G, CD41, Ter119, CD31, and CD142 surface proteins-evidence of neutrophil activation; platelet-neutrophil interaction; and vascular injury to brain, omentum, psoas, and skeletal muscles. Similar changes were found in mice exposed to high-pressure N2 using a gas mixture so that O2 partial pressure was the same as that of ambient air, whereas none of these changes occurred after exposures to 166 kPa O2, the same partial pressure that occurs during high-pressure air exposures. We conclude that N2 plays a central role in intra- and perivascular changes associated with exposure to high air pressure and that these responses appear to be a novel form of oxidative stress. Copyright © 2015 the American Physiological Society.

[Study of blood oxygen saturation, heart rate changes and plateau reaction of the Antarctic Kunlun station investigation team in different plateau environments].

PubMed

Zhao, Shun-yun; Wu, Xin-min; Guo, Ya-min; Zhang, Shu-shun; An, Yan-ming; Li, Bing; Wang, Hao

2013-06-11

To explore the blood oxygen saturation and heart rate changes of the Antarctic explorers. During August 2010 to April 2011, the changes in blood oxygen saturation, heart rate and plateau reaction of 16 Antarctic expedition team in different plateau environments (Tibetan plateau versus Antarctic plateau) were monitored with the noninvasive pulse oximeter MD300-C. The extent of acute mountain sickness was determined according to the Lake Louise Consensus acute mountain reaction symptom scores and judgment method. The changes of blood oxygen saturation, heart rate at different altitudes of 110, 3650, 4300 m (96.8% ± 1.2%,89.1% ± 1.2%, 86.1% ± 2.0%, (75.0 ± 5.4) times/min, (104.0 ± 4.3) times/min, (113.0 ± 5.2) times/min,F = 214.155, 240.088,both P < 0.05). With rising latitude and elevation gradient in Antarctic plateau, the changes of blood oxygen saturation, heart rate at different altitudes of 2000, 2500, 3000, 3500 and 4087 m(91.9% ± 1.3%,90.5% ± 1.3%,87.6% ± 1.4%,85.0% ± 1.8%,81.5% ± 2.2%, (85.9 ± 3.2) times/min, (90.6 ± 2.8) times/min, (97.8 ± 4.1) times/min, (102.0 ± 3.4) times/min, (106.3 ± 3.9) times/min, F = 105.418, 90.174, both P < 0.05). Levels of blood oxygen saturation and heart rate were both correlated with the risk of altitude sickness (r = -0.446 and 0.565, both P < 0.05). As the increases of altitude, there are significant changes in oxygen saturation, heart rate of the Antarctic explorers. And with the increases of altitude, the risk of altitude sickness gradually increases.

Salt stress causes cell wall damage in yeast cells lacking mitochondrial DNA.

PubMed

Gao, Qiuqiang; Liou, Liang-Chun; Ren, Qun; Bao, Xiaoming; Zhang, Zhaojie

2014-03-03

The yeast cell wall plays an important role in maintaining cell morphology, cell integrity and response to environmental stresses. Here, we report that salt stress causes cell wall damage in yeast cells lacking mitochondrial DNA (ρ 0 ). Upon salt treatment, the cell wall is thickened, broken and becomes more sensitive to the cell wall-perturbing agent sodium dodecyl sulfate (SDS). Also, SCW11 mRNA levels are elevated in ρ 0 cells. Deletion of SCW11 significantly decreases the sensitivity of ρ 0 cells to SDS after salt treatment, while overexpression of SCW11 results in higher sensitivity. In addition, salt stress in ρ 0 cells induces high levels of reactive oxygen species (ROS), which further damages the cell wall, causing cells to become more sensitive towards the cell wall-perturbing agent.

The relationship of metals, bifenthrin, physical habitat metrics, grain size, total organic carbon, dissolved oxygen and conductivity to Hyalella sp. abundance in urban California streams.

PubMed

Hall, Lenwood W; Anderson, Ronald D

2013-01-01

The objectives of this study were to determine the relationship between Hyalella sp. abundance in four urban California streams and the following parameters: (1) 8 bulk metals (As, Cd, Cr, Cu, Pb, Hg, Ni, and Zn) and their associated sediment Threshold Effect Levels (TELs); (2) bifenthrin sediment concentrations; (3) 10 habitat metrics and total score; (4) grain size (% sand, silt and clay); (5) Total Organic Carbon (TOC); (6) dissolved oxygen; and (7) conductivity. California stream data used for this study were collected from Kirker Creek (2006 and 2007), Pleasant Grove Creek (2006, 2007 and 2008), Salinas streams (2009 and 2010) and Arcade Creek (2009 and 2010). Hyalella abundance in the four California streams generally declined when metals concentrations were elevated beyond the TELs. There was also a statistically significant negative relationship between Hyalella abundance and % silt for these 4 California streams as Hyalella were generally not present in silt areas. No statistically significant relationships were reported between Hyalella abundance and metals concentrations, bifenthrin concentrations, habitat metrics, % sand, % clay, TOC, dissolved oxygen and conductivity. The results from this study highlight the complexity of assessing which factors are responsible for determining the abundance of amphipods, such as Hyalella sp., in the natural environment.

The effects of deoxygenation of adult and fetal hemoglobin on the synthesis of red cell 2,3-diphosphoglycerate and its in vivo consequences.

PubMed

Oski, F A; Gottlieb, A J; Miller, W W; Delivoria-Papadopoulos, M

1970-02-01

Patients over 1 month of age with arterial oxygen pressures of less than 60 mm Hg were found to have elevated red cell 2,3-diphosphoglycerate (2,3-DPG) levels and blood with a decreased affinity for oxygen. The increase in 2,3-DPG was proportional to the degree of hypoxemia. In patients under 1 month of age this relationship was not observed. Red cells from adults, but not newborns, showed rapid increases in 2,3-DPG when incubated under nitrogen. Adult, but not fetal, deoxyhemoglobin was shown to facilitate in vitro synthesis of 2,3-DPG by binding this organic phosphate and relieving the product inhibition of 2,3-DPG mutase. Throughout a wide range change in oxygen affinity as measured by the P(50) is linear with respect to the 2,3-DPG concentration; a change of 430 mmumoles of 2,3-DPG/ml of red blood corpuscles (RBC) resulting in a change of the P(50) of 1 mm Hg. It appears that the 2,3-DPG of the adult's red cells responds rapidly to metabolic and environmental influences and in turn effects metabolism and the cellular environment. Many of these effects are not shared by the red cells of the newborn.

Nitrite produced by Mycobacterium tuberculosis in human macrophages in physiologic oxygen impacts bacterial ATP consumption and gene expression

PubMed Central

Cunningham-Bussel, Amy; Zhang, Tuo; Nathan, Carl F.

2013-01-01

In high enough concentrations, such as produced by inducible nitric oxide synthase (iNOS), reactive nitrogen species (RNS) can kill Mycobacterium tuberculosis (Mtb). Lesional macrophages in macaques and humans with tuberculosis express iNOS, and mice need iNOS to avoid succumbing rapidly to tuberculosis. However, Mtb’s own ability to produce RNS is rarely considered, perhaps because nitrate reduction to nitrite is only prominent in axenic Mtb cultures at oxygen tensions ≤1%. Here we found that cultures of Mtb-infected human macrophages cultured at physiologic oxygen tensions produced copious nitrite. Surprisingly, the nitrite arose from the Mtb, not the macrophages. Mtb responded to nitrite by ceasing growth; elevating levels of ATP through reduced consumption; and altering the expression of 120 genes associated with adaptation to acid, hypoxia, nitric oxide, oxidative stress, and iron deprivation. The transcriptomic effect of endogenous nitrite was distinct from that of nitric oxide. Thus, whether or not Mtb is hypoxic, the host expresses iNOS, or hypoxia impairs the action of iNOS, Mtb in vivo is likely to encounter RNS by producing nitrite. Endogenous nitrite may slow Mtb’s growth and prepare it to resist host stresses while the pathogen waits for immunopathology to promote its transmission. PMID:24145454

CO2 clearance by membrane lungs.

PubMed

Sun, Liqun; Kaesler, Andreas; Fernando, Piyumindri; Thompson, Alex J; Toomasian, John M; Bartlett, Robert H

2018-05-01

Commercial membrane lungs are designed to transfer a specific amount of oxygen per unit of venous blood flow. Membrane lungs are much more efficient at removing CO 2 than adding oxygen, but the range of CO 2 transfer is rarely reported. Commercial membrane lungs were studied with the goal of evaluating CO 2 removal capacity. CO 2 removal was measured in 4 commercial membrane lungs under standardized conditions. CO 2 clearance can be greater than 4 times that of oxygen at a given blood flow when the gas to blood flow ratio is elevated to 4:1 or 8:1. The CO 2 clearance was less dependent on surface area and configuration than oxygen transfer. Any ECMO system can be used for selective CO 2 removal.

Chemistry of the metal-polymer interfacial region.

PubMed

Leidheiser, H; Deck, P D

1988-09-02

In many polymer-metal systems, chemical bonds are formed that involve metal-oxygen-carbon complexes. Infrared and Mössbauer spectroscopic studies indicate that carboxylate groups play an important role in some systems. The oxygen sources may be the polymer, the oxygen present in the oxide on the metal surface, or atmospheric oxygen. Diffusion of metal ions from the substrate into the polymer interphase may occur in some systems that are cured at elevated temperatures. It is unclear whether a similar, less extensive diffusion occurs over long time periods in systems maintained at room temperature. The interfacial region is dynamic, and chemical changes occur with aging at room temperature. Positron annihilation spectroscopy may have application to characterizing the voids at the metal-polymer interface.

Copper crystallite in carbon molecular sieves for selective oxygen removal

NASA Technical Reports Server (NTRS)

Sharma, Pramod K. (Inventor); Seshan, Panchalam K. (Inventor)

1993-01-01

Carbon molecular sieves modified by the incorporation of finely divided elemental copper useful for the selective sorption of oxygen at elevated temperatures. The carbon molecular sieves can be regenerated by reduction with hydrogen. The copper modified carbon molecular sieves are prepared by pyrolysis of a mixture of a copper-containing material and polyfurfuryl alcohol to form a sorbent precursor. The sorbent precursors are then heated and reduced to produce copper modified carbon molecular sieves. The copper modified carbon molecular sieves are useful for sorption of all concentrations of oxygen at temperatures up to about 200.degree. C. They are also useful for removal of trace amount of oxygen from gases at temperatures up to about 600.degree. C.

Hepatoprotective effect of 10% ethanolic extract from Curdrania tricuspidata leaves against ethanol-induced oxidative stress through suppression of CYP2E1.

PubMed

You, Yanghee; Min, Seoyoung; Lee, Yoo-Hyun; Hwang, Kwontack; Jun, Woojin

2017-10-01

The hepatoprotective effect of 10% ethanolic extract of Curdrania tricuspidata (CTE) was investigated in HepG2/2E1 cells and C57BL/6 J mice. When compared ethanol-only treated HepG2/2E1 cells, pretreatment of CTE prevented increased intra-cellular reactive oxygen species levels and decreased antioxidant activities by ethanol-induced oxidative stress. In C57BL/6 J mice, CTE at a dose of 250 mg/kg/day was administered for 10 days, with ethanol (5 g/kg/day) administered for the final 3 days. Pretreatment with CTE prevented the elevated activities of serum aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase caused by ethanol-induced hepatic damage. CTE-treated mice displayed a reduced level of malondialdehyde and increased antioxidant activities of catalase, glutathione S-transferase, glutathione peroxidase, and superoxide dismutase, as well as a reduced level of glutathione as compared with ethanol-only-treated mice. CTE-treated mice exhibited significant inhibition of CYP2E1 activities and expression. These results suggest that CTE could be a useful agent for the prevention of ethanol-induced oxidative damage in the liver, elevating antioxidative potentials and alleviating oxidative stress by suppressing CYP2El. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effects of deoxygenation on active and passive Ca2+ transport and on the cytoplasmic Ca2+ levels of sickle cell anemia red cells.

PubMed

Etzion, Z; Tiffert, T; Bookchin, R M; Lew, V L

1993-11-01

Elevated [Ca2+]i in deoxygenated sickle cell anemia (SS) red cells (RBCs) could trigger a major dehydration pathway via the Ca(2+)-sensitive K+ channel. But apart from an increase in calcium permeability, the effects of deoxygenation on the Ca2+ metabolism of sickle cells have not been previously documented. With the application of 45Ca(2+)-tracer flux methods and the combined use of the ionophore A23187, Co2+ ions, and intracellular incorporation of the Ca2+ chelator benz-2, in density-fractionated SS RBCs, we show here for the first time that upon deoxygenation, the mean [Ca2+]i level of SS discocytes was significantly increased, two- to threefold, from a normal range of 9.4 to 11.4 nM in the oxygenated cells, to a range of 21.8 to 31.7 nM in the deoxygenated cells, closer to K+ channel activatory levels. Unlike normal RBCs, deoxygenated SS RBCs showed a two- to fourfold increase in pump-leak Ca2+ turnover. Deoxygenation of the SS RBCs reduced their Ca2+ pump Vmax, more so in reticulocyte- and discocyte-rich than in dense cell fractions, and decreased their cytoplasmic Ca2+ buffering. Analysis of these results suggests that both increased Ca2+ influx and reduced Ca2+ pump extrusion contribute to the [Ca2+]i elevation.

HDT701, a histone H4 deacetylase, negatively regulates plant innate immunity by modulating histone H4 acetylation of defense-related genes in rice.

PubMed

Ding, Bo; Bellizzi, Maria del Rosario; Ning, Yuese; Meyers, Blake C; Wang, Guo-Liang

2012-09-01

Histone acetylation and deacetylation play an important role in the modification of chromatin structure and regulation of gene expression in eukaryotes. Chromatin acetylation status is modulated antagonistically by histone acetyltransferases and histone deacetylases (HDACs). In this study, we characterized the function of histone deacetylase701 (HDT701), a member of the plant-specific HD2 subfamily of HDACs, in rice (Oryza sativa) innate immunity. Transcription of HDT701 is increased in the compatible reaction and decreased in the incompatible reaction after infection by the fungal pathogen Magnaporthe oryzae. Overexpression of HDT701 in transgenic rice leads to decreased levels of histone H4 acetylation and enhanced susceptibility to the rice pathogens M. oryzae and Xanthomonas oryzae pv oryzae (Xoo). By contrast, silencing of HDT701 in transgenic rice causes elevated levels of histone H4 acetylation and elevated transcription of pattern recognition receptor (PRR) and defense-related genes, increased generation of reactive oxygen species after pathogen-associated molecular pattern elicitor treatment, as well as enhanced resistance to both M. oryzae and Xoo. We also found that HDT701 can bind to defense-related genes to regulate their expression. Taken together, these results demonstrate that HDT701 negatively regulates innate immunity by modulating the levels of histone H4 acetylation of PRR and defense-related genes in rice.