Science.gov

Sample records for intestinal oxygen uptake

  1. Effects of varying hematocrit on intestinal oxygen uptake in neonatal lambs

    SciTech Connect

    Holzman, I.R.; Tabata, B.; Edelstone, D.I.

    1985-04-01

    The authors chronically catheterized 15 newborn lambs (9.5 +/- 2.8 days) and measured intestinal blood flow (Qi) by the radionuclide microsphere technique at hematocrit levels ranging from 10 to 55%. Seven animals were made progressively anemic and eight polycythemic by means of exchange transfusions. Using the Fick principle, they calculated intestinal oxygen delivery (Di O/sub 2/), oxygen consumption (Vi O/sub 2/), and oxygen extraction. Initial base-line values were Qi = 195.5 ml . min-1 . 100 g intestine-1, Di O/sub 2/ = 22.1 ml . min-1 . 100 g-1, Vi O/sub 2/ = 4.8 ml . min-1 . 100 g-1, and O/sub 2/ extraction = 22.5%. As the hematocrit was lowered, Di O/sub 2/ decreased and O2 extraction increased and vice versa when the hematocrit was raised. Vi O/sub 2/ remained constant, but Qi did not correlate with changes in hematocrit. However, intestinal blood flow, as a percent distribution of total blood flow, decreased with lower hematocrit levels. At no time was there any evidence of anaerobic metabolism as measured by excess lactate production. The data indicate that the intestines of neonatal lambs are capable of maintaining their metabolic needs over a wide range of oxygen availability induced by a changing hematocrit. The primary mechanism is through alteration of oxygen extraction. Within the range of the experiments, no critically low oxygen availability was attained at which anaerobic metabolism became significant.

  2. Sugar uptake by intestinal basolateral membrane vesicles.

    PubMed

    Wright, E M; van Os, C H; Mircheff, A K

    1980-03-27

    A high yield of membrane vesicles was prepared from the basolateral surface of rat intestinal cells using an N2 cavitation bomb and density gradient centrifugation. The membranes were enriched 10-fold and were free of significatn contamination by brush border membranes and mitochondria. The rate of D-E114C]glucose and L-E13H]glucose uptake into the vesicle was measured using a rapid filtration technique. D-Glucose equilibrated within the vesicles with a half-time 1/25th that for L-glucose. The stereospecific uptake exhibited saturation kinetics with a Km of approx. 44 mM and a V of approx. 110 nmol . mg-1 min-1 at 10 degrees C. The activation energy for the process was 14 kcal . mol-1 below 15 degrees C and it approached 3 kcal . mol-1 above 22 degrees C. Carrier-mediated uptake was eliminated in the presence of 1 mM HgCl2 and 0.5 mM phloretin. The rate of transport was unaffected by the absence or presence of sodium concentration gradients. Competition studies demonstrated that all sugars with the D-glucose pyranose ring chair conformation shared the transport system, and that, with the possible exception of the -OH group at carbon No. 1, there were no specific requirements for an equatorial -OH group at any position in the pyranose ring. In the case of alpha-methyl-D-glucoside its inability to share the D-glucose transport system may be due to steric hindrance posed by the -OCH3 group rather than by a specific requirement for a free hydroxyl group at the position in the ring. It is concluded that sugars are transported across the basolateral membrane of the intestinal epithelium by a facilitated diffusion system reminiscent of that in human red blood cells. PMID:6245688

  3. Blood flow and oxygen uptake during exercise

    NASA Technical Reports Server (NTRS)

    Mitchell, J. W.; Stolwijk, J. A. J.; Nadel, E. R.

    1973-01-01

    A model is developed for predicting oxygen uptake, muscle blood flow, and blood chemistry changes under exercise conditions. In this model, the working muscle mass system is analyzed. The conservation of matter principle is applied to the oxygen in a unit mass of working muscle under transient exercise conditions. This principle is used to relate the inflow of oxygen carried with the blood to the outflow carried with blood, the rate of change of oxygen stored in the muscle myoglobin, and the uptake by the muscle. Standard blood chemistry relations are incorporated to evaluate venous levels of oxygen, pH, and carbon dioxide.

  4. OXYGEN UPTAKE AND NUTRIENT REGENERATION IN THE PECONIC ESTUARY

    EPA Science Inventory

    EXECUTIVE SUMMARY: OXYGEN UPTAKE AND NUTRIENT REGENERATION IN THE PECONIC ESTUARY Rates of oxygen consumption and nutrient regeneration were measured annually throughout the Peconic Estuarine System. Sediment and water column oxygen uptake were measured to determine the potential...

  5. 21 CFR 868.1730 - Oxygen uptake computer.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Oxygen uptake computer. 868.1730 Section 868.1730...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Diagnostic Devices § 868.1730 Oxygen uptake computer. (a) Identification. An oxygen uptake computer is a device intended to compute the amount of oxygen consumed by...

  6. 21 CFR 868.1730 - Oxygen uptake computer.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Oxygen uptake computer. 868.1730 Section 868.1730...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Diagnostic Devices § 868.1730 Oxygen uptake computer. (a) Identification. An oxygen uptake computer is a device intended to compute the amount of oxygen consumed by...

  7. 21 CFR 868.1730 - Oxygen uptake computer.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Oxygen uptake computer. 868.1730 Section 868.1730...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Diagnostic Devices § 868.1730 Oxygen uptake computer. (a) Identification. An oxygen uptake computer is a device intended to compute the amount of oxygen consumed by...

  8. 21 CFR 868.1730 - Oxygen uptake computer.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Oxygen uptake computer. 868.1730 Section 868.1730...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Diagnostic Devices § 868.1730 Oxygen uptake computer. (a) Identification. An oxygen uptake computer is a device intended to compute the amount of oxygen consumed by...

  9. 21 CFR 868.1730 - Oxygen uptake computer.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Oxygen uptake computer. 868.1730 Section 868.1730...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Diagnostic Devices § 868.1730 Oxygen uptake computer. (a) Identification. An oxygen uptake computer is a device intended to compute the amount of oxygen consumed by...

  10. Computer program for calculation of oxygen uptake

    NASA Technical Reports Server (NTRS)

    Castle, B. L.; Castle, G.; Greenleaf, J. E.

    1979-01-01

    A description and operational precedures are presented for a computer program, written in Super Basic, that calculates oxygen uptake, carbon dioxide production, and related ventilation parameters. Program features include: (1) the option of entering slope and intercept values of calibration curves for the O2 and CO2 and analyzers; (2) calculation of expired water vapor pressure; and (3) the option of entering inspured O2 and CO2 concentrations. The program is easily adaptable for programmable laboratory calculators.

  11. Acquisition of dietary copper: a role for anion transporters in intestinal apical copper uptake.

    PubMed

    Zimnicka, Adriana M; Ivy, Kristin; Kaplan, Jack H

    2011-03-01

    Copper is an essential micronutrient in humans and is required for a wide range of physiological processes, including neurotransmitter biosynthesis, oxidative metabolism, protection against reactive oxygen species, and angiogenesis. The first step in the acquisition of dietary copper is absorption from the intestinal lumen. The major human high-affinity copper uptake protein, human copper transporter hCTR1, was recently shown to be at the basolateral or blood side of both intestinal and renal epithelial cell lines and thus does not play a direct role in this initial step. We sought to functionally identify the major transport pathways available for the absorption of dietary copper across the apical intestinal membrane using Caco2 cells, a well-established model for human enterocytes. The initial rate of apical copper uptake into confluent monolayers of Caco2 cells is greatly elevated if amino acids and serum proteins are removed from the growth media. Uptake from buffered saline solutions at neutral pH (but not at lower pH) is inhibited by either d- or l-histidine, unaltered by the removal of sodium ions, and inhibited by ∼90% when chloride ions are replaced by gluconate or sulfate. Chloride-dependent copper uptake occurs with Cu(II) or Cu(I), although Cu(I) uptake is not inhibited by histidine, nor by silver ions. A well-characterized inhibitor of anion exchange systems, DIDS, inhibited apical copper uptake by 60-70%, while the addition of Mn(II) or Fe(II), competitive substrates for the divalent metal transporter DMT1, had no effect on copper uptake. We propose that anion exchangers play an unexpected role in copper absorption, utilizing copper-chloride complexes as pseudo-substrates. This pathway is also observed in mouse embryonic fibroblasts, human embryonic kidney cells, and Cos-7 cells. The special environment of low pH, low concentration of protein, and protonation of amino acids in the early intestinal lumen make this pathway especially important in

  12. Explanatory Variance in Maximal Oxygen Uptake

    PubMed Central

    Robert McComb, Jacalyn J.; Roh, Daesung; Williams, James S.

    2006-01-01

    The purpose of this study was to develop a prediction equation that could be used to estimate maximal oxygen uptake (VO2max) from a submaximal water running protocol. Thirty-two volunteers (n =19 males, n = 13 females), ages 18 - 24 years, underwent the following testing procedures: (a) a 7-site skin fold assessment; (b) a land VO2max running treadmill test; and (c) a 6 min water running test. For the water running submaximal protocol, the participants were fitted with an Aqua Jogger Classic Uni-Sex Belt and a Polar Heart Rate Monitor; the participants’ head, shoulders, hips and feet were vertically aligned, using a modified running/bicycle motion. A regression model was used to predict VO2max. The criterion variable, VO2max, was measured using open-circuit calorimetry utilizing the Bruce Treadmill Protocol. Predictor variables included in the model were percent body fat (% BF), height, weight, gender, and heart rate following a 6 min water running protocol. Percent body fat accounted for 76% (r = -0.87, SEE = 3.27) of the variance in VO2max. No other variables significantly contributed to the explained variance in VO2max. The equation for the estimation of VO2max is as follows: VO2max ml.kg-1·min-1 = 56.14 - 0.92 (% BF). Key Points Body Fat is an important predictor of VO2 max. Individuals with low skill level in water running may shorten their stride length to avoid the onset of fatigue at higher work-loads, therefore, the net oxygen cost of the exercise cannot be controlled in inexperienced individuals in water running at fatiguing workloads. Experiments using water running protocols to predict VO2max should use individuals trained in the mechanics of water running. A submaximal water running protocol is needed in the research literature for individuals trained in the mechanics of water running, given the popularity of water running rehabilitative exercise programs and training programs. PMID:24260003

  13. Muscular Oxygen Uptake Kinetics in Aged Adults.

    PubMed

    Koschate, J; Drescher, U; Baum, K; Eichberg, S; Schiffer, T; Latsch, J; Brixius, K; Hoffmann, U

    2016-06-01

    Pulmonary oxygen uptake (V˙O2) kinetics and heart rate kinetics are influenced by age and fitness. Muscular V˙O2 kinetics can be estimated from heart rate and pulmonary V˙O2. In this study the applicability of a test using pseudo-random binary sequences in combination with a model to estimate muscular V˙O2 kinetics was tested. Muscular V˙O2 kinetics were expected to be faster than pulmonary V˙O2 kinetics, slowed in aged subjects and correlated with maximum V˙O2 and heart rate kinetics. 27 elderly subjects (73±3 years; 81.1±8.2 kg; 175±4.7 cm) participated. Cardiorespiratory kinetics were assessed using the maximum of cross-correlation functions, higher maxima implying faster kinetics. Muscular V˙O2 kinetics were faster than pulmonary V˙O2 kinetics (0.31±0.1 vs. 0.29±0.1 s; p=0.004). Heart rate kinetics were not correlated with muscular or pulmonary V˙O2 kinetics or maximum V˙O2. Muscular V˙O2 kinetics correlated with maximum V˙O2 (r=0.35; p=0.033). This suggests, that muscular V˙O2 kinetics are faster than estimates from pulmonary V˙O2 and related to maximum V˙O2 in aged subjects. In the future this experimental approach may help to characterize alterations in muscular V˙O2 under various conditions independent of motivation and maximal effort. PMID:27116341

  14. Bile Diversion in Roux-en-Y Gastric Bypass Modulates Sodium-Dependent Glucose Intestinal Uptake.

    PubMed

    Baud, Gregory; Daoudi, Mehdi; Hubert, Thomas; Raverdy, Violeta; Pigeyre, Marie; Hervieux, Erik; Devienne, Magalie; Ghunaim, Mohamed; Bonner, Caroline; Quenon, Audrey; Pigny, Pascal; Klein, André; Kerr-Conte, Julie; Gmyr, Valery; Caiazzo, Robert; Pattou, François

    2016-03-01

    Gastro-intestinal exclusion by Roux-en-Y gastric bypass (RYGB) improves glucose metabolism, independent of weight loss. Although changes in intestinal bile trafficking have been shown to play a role, the underlying mechanisms are unclear. We performed RYGB in minipigs and showed that the intestinal uptake of ingested glucose is blunted in the bile-deprived alimentary limb (AL). Glucose uptake in the AL was restored by the addition of bile, and this effect was abolished when active glucose intestinal transport was blocked with phlorizin. Sodium-glucose cotransporter 1 remained expressed in the AL, while intraluminal sodium content was markedly decreased. Adding sodium to the AL had the same effect as bile on glucose uptake. It also increased postprandial blood glucose response in conscious minipigs following RYGB. The decrease in intestinal uptake of glucose after RYGB was confirmed in humans. Our results demonstrate that bile diversion affects postprandial glucose metabolism by modulating sodium-glucose intestinal cotransport. PMID:26924216

  15. IMPAIRED INTESTINAL VITAMIN B1 (THIAMIN) UPTAKE IN THIAMIN TRANSPORTER-2 DEFICIENT MICE

    PubMed Central

    Reidling, Jack C.; Lambrecht, Nils; Kassir, Mohammad; Said, Hamid M.

    2016-01-01

    BACKGROUND & AIMS Intestinal thiamin uptake process is vital for maintaining normal body homeostasis of the vitamin; in vitro studies suggest that both thiamin transporter-1 (THTR-1) and -2 (THTR-2) are involved. Mutations in THTR-1 cause thiamin-responsive megaloblastic anemia (TRMA), a tissue specific disease associated with diabetes mellitus, megaloblastic anemia, and sensorineural deafness. However in patients with TRMA, plasma thiamin levels are within normal range, indicating that THTR2 (or another carrier) could provide sufficient intestinal thiamin absorption. We tested this possibility and examined the role of THTR-2 in uptake of thiamin in the intestine of mice. METHODS THTR-2 deficient mice were generated by SLC19A3 gene knockout and used to examine intestinal uptake of thiamin in vitro (isolated cells) and in vivo (intact intestinal loops). We also examined intestinal thiamin uptake in THTR-1 deficient mice. RESULTS Intestine of THTR-2 deficient mice had reduced uptake of thiamin compared to those of wild –type littermate mice (p<0.01); this reduction was associated with a decrease (p<0.01) in blood thiamin levels in THTR-2 deficient mice. However, intestinal uptake of thiamin in THTR-1 deficient mice was not significantly different from that of wild-type littermate animals. Level of expression of THTR-1 was not altered in the intestine of THTR-2 deficient mice, but level of expression of THTR-2 was up-regulated in the intestine of THTR-1 deficient mice. CONCLUSION THTR-2 is required for normal uptake of thiamin in the intestine and can fulfill normal levels of uptake in conditions associated with THTR-1 dysfunction. PMID:19879271

  16. Relationship between maximal oxygen uptake and oxygen uptake attained during treadmill middle-distance running.

    PubMed

    James, David V B; Sandals, Leigh E; Draper, Stephen B; Wood, Dan M

    2007-06-01

    Traditionally, it has been assumed that during middle-distance running oxygen uptake (VO2) reaches its maximal value (VO2max) providing the event is of a sufficient duration; however, this assumption is largely based on observations in individuals with a relatively low VO2max. The aim of this study was to determine whether VO2max is related to the VO2 attained (i.e. VO2peak) during middle-distance running on a treadmill. Fifteen well-trained male runners (age 23.3 +/- 3.8 years, height 1.80 +/- 0.10 m, body mass 76.9 +/- 10.6 kg) volunteered to participate in the study. The participants undertook two 800-m trials to examine the reproducibility of the VO2 response. These two trials, together with a progressive test to determine VO2max, were completed in a randomized order. Oxygen uptake was determined throughout each test using 15-s Douglas bag collections. Following the application of a 30-s rolling average, the highest VO2 during the progressive test (i.e. VO2max) was compared with the highest VO2 during the 800-m trials (i.e. VO2peak) to examine the relationship between VO2max and the VO2 attained in the 800-m trials. For the 15 runners, VO2max was 58.9 +/- 7.1 ml x kg(-1) x min(-1). Two groups were formed using a median split based on VO2max. For the high and low VO2max groups, VO2max was 65.7 +/- 3.0 and 52.4 +/- 1.8 ml x kg(-1) x min(-1) respectively. The limits of agreement (95%) for test-retest reproducibility for the VO2 attained during the 800-m trials were +/- 3.5 ml x kg(-1) x min(-1) for a VO2peak of 50.6 ml x kg(-1) x min(-1) (the mean VO2peak for the low VO2max group) and +/- 2.3 ml x kg(-1) x min(-1) for a VO2peak of 59.0 ml x kg(-1) x min(-1) (the mean VO2peak for the high VO2max group), with a bias in VO2peak between the 800-m runs (i.e. the mean difference) of 1.2 ml x kg(-1) x min(-1). The VO2peak for the 800-m runs was 54.8 +/- 4.9 ml x kg(-1) x min(-1) for all 15 runners. For the high and low VO2max groups, VO2peak was 59.0 +/- 3.3 ml x kg(-1

  17. Maximum Oxygen Uptake Determination in Insulin-Dependent Diabetes Mellitus.

    ERIC Educational Resources Information Center

    Fremion, Amy S.; And Others

    1987-01-01

    A study of 10 children with insulin-dependent diabetes mellitus performing a maximum-effort cycling test indicated blood glucose levels did not change appreciably during test, while maximal oxygen uptake was substandard for their age groups. Findings suggest patients in fair to poor metabolic control can tolerate stress testing without…

  18. Glyceroglycolipids Affect Uptake of Carotenoids Solubilized in Mixed Micelles by Human Intestinal Caco-2 Cells.

    PubMed

    Kotake-Nara, Eiichi; Yonekura, Lina; Nagao, Akihiko

    2015-09-01

    We previously reported that phospholipids markedly affected the uptake of carotenoids solubilized in mixed micelles by human intestinal Caco-2 cells. In the present study, we found that two classes of dietary glyceroglycolipids and the corresponding lysoglyceroglycolipids affected uptake of β-carotene and lutein by differentiated Caco-2 cells. The levels of carotenoid uptake from micelles containing digalactosyldiacylglycerol or sulfoquinovosyldiacylglycerol were significantly lower than that from control micelles. On the other hand, the uptakes from micelles containing digalactosylmonoacylglycerol or sulfoquinovosylmonoacylglycerol were significantly higher than that from control micelles. In dispersed cells and Caco-2 cells with poor cell-to-cell adhesion, however, the levels of uptake from micelles containing these lyso-lipids were much lower than that from control micelles. The uptake levels from control micelles were markedly decreased depending on the development of cell-to-cell/cell-matrix adhesion in Caco-2 cells, but the uptake levels from the micelles containing these lyso-lipids were not substantially changed, suggesting that the intercellular barrier formed by cell-to-cell/cell-matrix adhesion inhibited the uptake from control micelles, but not from the lyso-lipid-containing micelles. The lyso-lipids appeared to enhance carotenoid uptake by decreasing the intercellular barrier integrity. The results showed that some types of glyceroglycolipids have the potential to modify the intestinal uptake of carotenoids. PMID:26012480

  19. One minute oxygen uptake in peripheral ischemic vascular disease.

    PubMed Central

    Auchincloss, J H; Meade, J W; Gilbert, R; Chamberlain, B E

    1980-01-01

    Six males, ages 31-58, with ischemic vascular disease of the lower extremities, underwent treadmill testing with measurement of oxygen uptake at 45-60 seconds of exercise (VO2-45-60) as the test score. Tests were performed at 41, 123 and 164 watts of power against gravity. Depressed values were found in five subjects with aortic, iliac or common femoral disease but normal values in a subject with narrowing of the left superficial femoral artery. Reconstructive surgery resulted in normal values in four subjects retested. In three of these a calculation was made of the increased volume of oxygen uptake during the first minute of exercise associated with postsurgical improvement. The average was 430 ml, a value high enough to suggest increased aerobic metabolism of exercising muscles. PMID:7362287

  20. Reference Values of Maximal Oxygen Uptake for Polish Rowers

    PubMed Central

    Klusiewicz, Andrzej; Starczewski, Michał; Ładyga, Maria; Długołęcka, Barbara; Braksator, Wojciech; Mamcarz, Artur; Sitkowski, Dariusz

    2014-01-01

    The aim of this study was to characterize changes in maximal oxygen uptake over several years and to elaborate current reference values of this index based on determinations carried out in large and representative groups of top Polish rowers. For this study 81 female and 159 male rowers from the sub-junior to senior categories were recruited from the Polish National Team and its direct backup. All the subjects performed an incremental exercise test on a rowing ergometer. During the test maximal oxygen uptake was measured with the BxB method. The calculated reference values for elite Polish junior and U23 rowers allowed to evaluate the athletes’ fitness level against the respective reference group and may aid the coach in controlling the training process. Mean values of VO2max achieved by members of the top Polish rowing crews who over the last five years competed in the Olympic Games or World Championships were also presented. The results of the research on the “trainability” of the maximal oxygen uptake may lead to a conclusion that the growth rate of the index is larger in case of high-level athletes and that the index (in absolute values) increases significantly between the age of 19–22 years (U23 category). PMID:25713672

  1. Measuring oxygen uptake in fishes with bimodal respiration.

    PubMed

    Lefevre, S; Bayley, M; McKenzie, D J

    2016-01-01

    Respirometry is a robust method for measurement of oxygen uptake as a proxy for metabolic rate in fishes, and how species with bimodal respiration might meet their demands from water v. air has interested researchers for over a century. The challenges of measuring oxygen uptake from both water and air, preferably simultaneously, have been addressed in a variety of ways, which are briefly reviewed. These methods are not well-suited for the long-term measurements necessary to be certain of obtaining undisturbed patterns of respiratory partitioning, for example, to estimate traits such as standard metabolic rate. Such measurements require automated intermittent-closed respirometry that, for bimodal fishes, has only recently been developed. This paper describes two approaches in enough detail to be replicated by the interested researcher. These methods are for static respirometry. Measuring oxygen uptake by bimodal fishes during exercise poses specific challenges, which are described to aid the reader in designing experiments. The respiratory physiology and behaviour of air-breathing fishes is very complex and can easily be influenced by experimental conditions, and some general considerations are listed to facilitate the design of experiments. Air breathing is believed to have evolved in response to aquatic hypoxia and, probably, associated hypercapnia. The review ends by considering what realistic hypercapnia is, how hypercapnic tropical waters can become and how this might influence bimodal animals' gas exchange. PMID:26358224

  2. Echocardiographic dimensions and maximal oxygen uptake in oarsmen during training.

    PubMed Central

    Wieling, W; Borghols, E A; Hollander, A P; Danner, S A; Dunning, A J

    1981-01-01

    We studied nine freshmen and 14 senior oarsmen undergraduates during seven months of training and compared them with 17 age and sex-matched sedentary control subjects in order to assess the influence of heavy physical exercise on cardiac dimensions and maximal oxygen uptake. Standard M-mode echocardiographic techniques were used. At the start of the season senior oarsmen had a greater left ventricular end-diastolic dimension, and a thicker interventricular septum and posterior left ventricular wall than control subjects and freshmen oarsmen. The two latter groups did not differ from each other. During the training period there was a slight and gradual increase in left ventricular end-diastolic dimension, and interventricular septum and posterior wall thickness in freshmen. In seniors only left ventricular end-diastolic dimension increased significantly. Maximal oxygen uptake showed a distinct increase between the fourth and seventh month during the period of intensive rowing training. There was no relation between echocardiographic variables and maximal oxygen uptake. A combination of heavy dynamic and static exercise can thus lead to significant changes in both left ventricular wall thickness and chamber size within months. Echocardiographic variables measured at rest cannot be used as a suitable index of performance capacity. PMID:7272130

  3. Reference values of maximal oxygen uptake for polish rowers.

    PubMed

    Klusiewicz, Andrzej; Starczewski, Michał; Ładyga, Maria; Długołęcka, Barbara; Braksator, Wojciech; Mamcarz, Artur; Sitkowski, Dariusz

    2014-12-01

    The aim of this study was to characterize changes in maximal oxygen uptake over several years and to elaborate current reference values of this index based on determinations carried out in large and representative groups of top Polish rowers. For this study 81 female and 159 male rowers from the sub-junior to senior categories were recruited from the Polish National Team and its direct backup. All the subjects performed an incremental exercise test on a rowing ergometer. During the test maximal oxygen uptake was measured with the BxB method. The calculated reference values for elite Polish junior and U23 rowers allowed to evaluate the athletes' fitness level against the respective reference group and may aid the coach in controlling the training process. Mean values of VO2max achieved by members of the top Polish rowing crews who over the last five years competed in the Olympic Games or World Championships were also presented. The results of the research on the "trainability" of the maximal oxygen uptake may lead to a conclusion that the growth rate of the index is larger in case of high-level athletes and that the index (in absolute values) increases significantly between the age of 19-22 years (U23 category). PMID:25713672

  4. Differentiation-dependent regulation of intestinal vitamin B2 uptake: studies utilizing human-derived intestinal epithelial Caco-2 cells and native rat intestine

    PubMed Central

    Subramanian, Veedamali S.; Ghosal, Abhisek; Subramanya, Sandeep B.; Lytle, Christian

    2013-01-01

    Intestinal epithelial cells undergo differentiation as they move from the crypt to the villi, a process that is associated with up- and downregulation in expression of a variety of genes, including those involved in nutrient absorption. Whether the intestinal uptake process of vitamin B2 [riboflavin (RF)] also undergoes differentiation-dependent regulation and the mechanism through which this occurs are not known. We used human-derived intestinal epithelial Caco-2 cells and native rat intestine as models to address these issues. Caco-2 cells showed a significantly higher carrier-mediated RF uptake in post- than preconfluent cells. This upregulation was associated with a significantly higher level of protein and mRNA expression of the RF transporters hRFVT-1 and hRFVT-3 in the post- than preconfluent cells; it was also accompanied with a significantly higher rate of transcription of the respective genes (SLC52A1 and SLC52A3), as indicated by the higher level of expression of heterogeneous nuclear RNA and higher promoter activity in post- than preconfluent cells. Studies with native rat intestine also showed a significantly higher RF uptake by epithelial cells of the villus tip than epithelial cells of the crypt; this again was accompanied by a significantly higher level of expression of the rat RFVT-1 and RFVT-3 at the protein, mRNA, and heterogeneous nuclear RNA levels. These findings show, for the first time, that the intestinal RF uptake process undergoes differentiation-dependent upregulation and suggest that this is mediated (at least in part) via transcriptional mechanisms. PMID:23413253

  5. Uptake and dynamics of infectious prion protein in the intestine.

    PubMed

    Ano, Yasuhisa; Sakudo, Akikazu; Nakayama, Hiroyuki; Onodera, Takashi

    2009-01-01

    Transmissible spongiform encephalopathies (TSEs) are characterized by the accumulation of a protease-resistant abnormal isoform of the prion protein (PrPSc), which is converted from the cellular isoform of the prion protein (PrPC). In the oral transmission of prion protein, PrPSc can invade a host body through the intestinal tract. There is only limited information available on how the infectious agent passes through one or several biological barriers before it can finally reach the brain. After oral administration, PrPSc withstands the digestive process and may be incorporated by microfold (M) cells or villous columnar epithelial cells in the intestine. After entry into the intestinal epithelium, PrPSc accumulates and is amplified in follicular dendritic cells (FDCs) within Peyer's patches and other isolated lymphoid follicles possibly by an interaction with dendritic cells or macrophages. Following accumulation in gut-associated lymphoid tissues, PrPSc is thought to move to the enteric nervous systems (ENS) by an interaction with FDCs or dendritic cells. As a result of neuroinvasion into the ENS, PrPSc spreads to the central nervous system. In addition, an epidemiological study suggested that most bovine spongiform encephalopathy cases had been exposed to the agent in the first 6 months of life. Developments of the intestinal defense and immune system may be involved in the susceptibility to infection. PMID:19275737

  6. Modeling oxygen dissolution and biological uptake during pulse oxygen additions in oenological fermentations.

    PubMed

    Saa, Pedro A; Moenne, M Isabel; Pérez-Correa, J Ricardo; Agosin, Eduardo

    2012-09-01

    Discrete oxygen additions during oenological fermentations can have beneficial effects both on yeast performance and on the resulting wine quality. However, the amount and time of the additions must be carefully chosen to avoid detrimental effects. So far, most oxygen additions are carried out empirically, since the oxygen dynamics in the fermenting must are not completely understood. To efficiently manage oxygen dosage, we developed a mass balance model of the kinetics of oxygen dissolution and biological uptake during wine fermentation on a laboratory scale. Model calibration was carried out employing a novel dynamic desorption-absorption cycle based on two optical sensors able to generate enough experimental data for the precise determination of oxygen uptake and volumetric mass transfer coefficients. A useful system for estimating the oxygen solubility in defined medium and musts was also developed and incorporated into the mass balance model. Results indicated that several factors, such as the fermentation phase, wine composition, mixing and carbon dioxide concentration, must be considered when performing oxygen addition during oenological fermentations. The present model will help develop better oxygen addition policies in wine fermentations on an industrial scale. PMID:22349928

  7. Effects of dietary starch source on electrophysiological intestinal epithelial properties and intestinal glucose uptake in growing goats.

    PubMed

    Klinger, Stefanie; Zurich, Meike; Schröder, Bernd; Breves, Gerhard

    2013-08-01

    In ruminants, the potential benefit of by-pass starch to improve energy supply is under discussion. As efficient intestinal starch digestion and monosaccharide absorption are important prerequisites for an energetic benefit compared to ruminal fermentation, this study was conducted to characterise potential adaptations of intestinal tissues to different dietary starch sources qualitatively. The Ussing chamber technique was used to determine electrophysiological parameters of jejunal tissues and glucose flux rates. Kinetics of sodium-dependent glucose uptake into isolated brush-border membrane vesicles (BBMV) were calculated, and the expression level of sodium-dependent glucose transporter 1 (SGLT1) was determined. Samples were collected from goats that were assigned to three dietary treatments differing in starch content (hay/concentrate) and starch source (wheat/corn). Additionally, ingesta samples were analysed for starch and glucose contents. Jejunal tissues from hay-fed animals showed higher tissue conductances (G t) and numerically higher short-circuit currents (I sc). Unidirectional glucose flux rates were higher for hay-fed animals, whereas net flux rates were unaffected. The maximal glucose transport capacity into BBMV was increased for concentrate-fed animals, but the affinity and SGLT1 expression were not affected. Our results may indicate an adaptation of glucose uptake via SGLT1 to variations in dietary starch but it could not be excluded that intestinal uptake capacity was saturated under the given conditions or that the measured capacity was sufficient for absorption of available glucose. PMID:23879718

  8. Heart size estimated by echocardiography correlates with maximal oxygen uptake.

    PubMed

    Young, L E; Marlin, D J; Deaton, C; Brown-Feltner, H; Roberts, C A; Wood, J L N

    2002-09-01

    Maximum oxygen uptake also appears to correlate to athletic performance in horses. In the Thoroughbred industry, there has long been an empirical theory that heart size is related to athletic performance, despite a lack of scientific evidence supporting this assertion. To investigate the relationship between peak oxygen consumption (VO2max) and cardiac size measured by echocardiography, guided M-mode and 2-dimensional echocardiography were performed in 17 conditioned Thoroughbreds with a range of VO2max from 126 to 217 ml/min/kg STPD (mean +/- s.d. 158 +/- 28 m/min/kg). Horses were age 2-10 years and weighed 430-510 kg. Echocardiography was performed using a Vingmed System V echocardiograph with a 2.25 MHz phased array ultrasound transducer. All images were obtained from the right hemithorax using a short axis view of the left ventricle (LV) at the level of the chordae tendinae. All horses were free from significant regurgitation at the aortic or mitral valves. Maximal oxygen uptake was measured during a standardised incremental treadmill exercise test to fatigue. Maximal oxygen uptake was correlated significantly with LVIDd (r = 0.71; P = 0.001), MWT (r = 0.72; P = 0.001), LV mass (r = 0.78; P = 0.0002) and LV short-axis area (r = 0.69; P = 0.003). When indices of heart size were indexed to bodyweight, the correlation between VO2max and indices of heart size were LVIDd (r = 0.57; P = 0.01), MWT (r = 0.44; P = 0.07), LV mass (r = 0.78; P = 0.0002) and LV short-axis area (r = 0.69; P = 0.003). The current study suggests there is a strong relationship between VO2max and measurements of left ventricular size in Thoroughbred horses when individuals with a range of VO2max are compared. PMID:12405735

  9. Chemical form of selenium affects its uptake, transport and glutathione peroxidase activity in the human intestinal Caco-2 cell model

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Determining the effect of selenium (Se) chemical form on uptake and transport in human intestinal cells is critical to assess Se bioavailability. In the present study, we measured the uptake and transport of various Se compounds in the human intestinal Caco-2 cell model. We found that two sources...

  10. Branchial versus intestinal silver toxicity and uptake in the marine teleost Parophrys vetulus.

    PubMed

    Grosell, M; Wood, C M

    2001-10-01

    Exposure to elevated waterborne silver as AgNO3 (4.07 microM=448 microg l(-1)) in seawater resulted in osmoregulatory disturbance in the lemon sole (Parophrys vetulus). The main effects were increased plasma Na+ and Cl- concentrations which translated into increased plasma osmolality. Plasma Mg2+ levels were also slightly increased after 96 h exposure. Using radioisotopic flux measurements, a 50% reduction in branchial unidirectional Na+ extrusion was observed after 48 h silver exposure. By applying an intestinal perfusion approach, we were able to separate and thus quantify the intestinal contribution to the observed silver-induced physiological disturbance and internal silver accumulation. This analysis revealed that the intestinal contribution to silver-induced ionoregulatory toxicity was as high as 50-60%. In marked contrast, internal silver accumulation (in liver and kidney) was found to be derived exclusively from uptake across the gills. Drinking of silver-contaminated seawater resulted in substantial silver accumulation in the intestinal tissue (but apparently not silver uptake across the intestine), which probably explains the intestinal contribution to silver-induced physiological disturbance. PMID:11686617

  11. Uptake of codeine into intestinal epithelial (Caco-2) and brain endothelial (RBE4) cells.

    PubMed

    Fischer, Wiebke; Bernhagen, Jennifer; Neubert, Reinhard H H; Brandsch, Matthias

    2010-09-11

    Orally administered codeine has to permeate both the intestinal and the blood-brain barrier in order to act as analgesic and cough suppressant. In this study we characterized the uptake of codeine at intestinal epithelial (Caco-2) and brain endothelial (RBE4) cells. At both cell types, uptake of [(3)H]codeine was independent of an inwardly directed Na(+) gradient. Uptake was, however, strongly stimulated by an outwardly directed H(+) gradient and inhibited by the protonophore FCCP. [(3)H]Codeine uptake into Caco-2 cells was strongly temperature dependent. In the presence of excess amounts of unlabeled codeine, the uptake was inhibited by up to 87% (Caco-2) or 94% (RBE4), respectively. Synthetic opioids and some non-opioid organic cations like propranolol, pyrilamine and quinidine potently inhibited [(3)H]codeine uptake. Several prototype substrates of known transporters for amino acids, neurotransmitters and organic cations were ineffective. Our data are consistent with a hypothetic saturable, H(+)-dependent (antiport) mechanism not yet identified on a molecular level. The pH dependence of codeine uptake and its intracellular accumulation can partially also be explained by a model comprising diffusional membrane permeation of unionized species of codeine followed by codeine sequestration into acidic vesicles and distribution into cellular lipids. PMID:20510359

  12. Cardiovascular consequences of bed rest: effect on maximal oxygen uptake.

    PubMed

    Convertino, V A

    1997-02-01

    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

  13. 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

  14. Ursodeoxycholic and deoxycholic acids: Differential effects on intestinal Ca(2+) uptake, apoptosis and autophagy of rat intestine.

    PubMed

    Rodríguez, Valeria A; Rivoira, María A; Pérez, Adriana del V; Marchionatti, Ana M; Tolosa de Talamoni, Nori G

    2016-02-01

    The aim of this work was to study the effect of sodium deoxycholate (NaDOC) and ursodeoxycholic acid (UDCA) on Ca(2+) uptake by enterocytes and the underlying mechanisms. Rats were divided into four groups: a) controls, b) treated with NaDOC, c) treated with UDCA d) treated with NaDOC and UDCA. Ca(2+) uptake was studied in enterocytes with different degrees of maturation. Apoptosis, autophagy and NO content and iNOS protein expression were evaluated. NaDOC decreased and UDCA increased Ca(2+) uptake only in mature enterocytes. The enhancement of protein expression of Fas, FasL, caspase-8 and caspase-3 activity by NaDOC indicates triggering of the apoptotic extrinsic pathway, which was blocked by UDCA. NO content and iNOS protein expression were enhanced by NaDOC, and avoided by UDCA. The increment of acidic vesicular organelles and LC3 II produced by NaDOC was also prevented by UDCA. In conclusion, the inhibitory effects of NaDOC on intestinal Ca(2+) absorption occur by decreasing the Ca(2+) uptake by mature enterocytes. NaDOC triggers apoptosis and autophagy, in part as a result of nitrosative stress. In contrast, UDCA increases the Ca(2+) uptake by mature enterocytes, and in combination with NaDOC acts as an antiapoptotic and antiautophagic agent normalizing the transcellular Ca(2+) pathway. PMID:26707246

  15. Oxygen uptake during modern dance class, rehearsal, and performance.

    PubMed

    Wyon, Matthew A; Abt, Grant; Redding, Emma; Head, Andrew; Sharp, N Craig C

    2004-08-01

    The aim of the present study was to examine whether the workload, expressed in oxygen uptake and heart rate, during dance class and rehearsal prepared the dancer for performance. Previous research on the demands of class and performance has been affected by equipment limitations and could only provide limited insight into the physiological demands placed on the dancer. The present study noted that dance performance had significantly greater mean oxygen uptake and heart rate than noted in both class and rehearsal (p < 0.05). Further analysis noted that, during class and rehearsal, heart rates were rarely within the aerobic training zone (60-90%HRmax, where HRmax is the maximum heart rate). Dance performance placed a greater demand on the aerobic and anaerobic glycolytic energy systems than seen during class and rehearsal, which placed a greater emphasis on the adenosine triphosphate-creatine phosphate system. Practical implications suggest the need to supplement training within dance companies to overcome this deficit in training demand. PMID:15320648

  16. The Relationship between Heart Rate Reserve and Oxygen Uptake Reserve in Children and Adolescents

    ERIC Educational Resources Information Center

    Hui, Stanley Sai-chuen; Chan, Janus Wan-sze

    2006-01-01

    The purpose of the present study was to examine the relationship between oxygen uptake (VO[subscript 2]) and heart rate (HR) responses during rest and exercise in Chinese children and youth and to evaluate the relationships between maximal heart rate (%HRmax), heart rate reserve (%HRR), peak oxygen uptake (%VO[subscript 2]peak), and oxygen uptake…

  17. Can bioadhesive nanoparticles allow for more effective particle uptake from the small intestine?

    PubMed

    Reineke, J; Cho, D Y; Dingle, Y L; Cheifetz, P; Laulicht, B; Lavin, D; Furtado, S; Mathiowitz, E

    2013-09-28

    There has been increasing interest in developing bioadhesive nanoparticles due to their great potential as carriers for therapeutics in oral drug delivery systems. Despite decades of research, such a system still has not been successfully implemented. This paper demonstrates the enormous potential of such engineered systems: the incorporation of a bioadhesive coating, poly(butadiene-maleic anhydride-co-L-DOPA) (PBMAD), to non-bioadhesive nanospheres resulted in an enhancement of particle uptake in the small intestine from 5.8±1.9% to 66.9±12.9%. Direct correlation was obtained between bulk tensile strength, in vitro binding to everted intestinal sacs and quantitative in vivo uptake; this data suggests that bulk properties of polymers can be used to predict bioadhesive properties of nano- and microparticles. The differential distribution of the nanospheres to various tissues following uptake suggests surface chemistry plays a significant role in their localization within the body. The results of these studies provide strong support for the use of bioadhesive polymers to enhance nano- and micro-particle uptake from the small intestine for oral drug delivery. PMID:23796432

  18. Linking Pulmonary Oxygen Uptake, Muscle Oxygen Utilization and Cellular Metabolism during Exercise

    PubMed Central

    Lai, Nicola; Camesasca, Marco; Saidel, Gerald M.; Dash, Ranjan K.; Cabrera, Marco E.

    2014-01-01

    The energy demand imposed by physical exercise on the components of the oxygen transport and utilization system requires a close link between cellular and external respiration in order to maintain ATP homeostasis. Invasive and non-invasive experimental approaches have been used to elucidate mechanisms regulating the balance between oxygen supply and consumption during exercise. Such approaches suggest that the mechanism controlling the various subsystems coupling internal to external respiration are part of a highly redundant and hierarchical multi-scale system. In this work, we present a “systems biology” framework that integrates experimental and theoretical approaches able to provide simultaneously reliable information on the oxygen transport and utilization processes occurring at the various steps in the pathway of oxygen from air to mitochondria, particularly at the onset of exercise. This multi-disciplinary framework provides insights into the relationship between cellular oxygen consumption derived from measurements of muscle oxygenation during exercise and pulmonary oxygen uptake by indirect calorimetry. With a validated model, muscle oxygen dynamic responses is simulated and quantitatively related to cellular metabolism under a variety of conditions. PMID:17380394

  19. Maximal oxygen uptake during exercise using trained or untrained muscles.

    PubMed

    Moreira-da-Costa, M; Russo, A K; Piçarro, I C; Silva, A C; Leite-de-Barros-Neto, T; Tarasantchi, J; Barbosa, A S

    1984-01-01

    Maximal oxygen uptake, VO2 max, was determined for cyclists, long-distance runners and non-athletes during uphill running (treadmill) and cycling (cycloergometer) to compare trained and untrained muscles. Blood lactate, maximal heart rate and maximal ventilation during work were also measured. VO2 max was higher for runners and non-athletes during exercise on the treadmill and higher for cyclists during exercise on the cycloergometer. For runners and non-athletes, maximal heart rate accompanied the increase in VO2 max, whereas similar values were obtained for cyclists on both ergometers. Maximal ventilation during work accompanied the difference in VO2 max in both groups of athletes but among non-athletes it was similar during exercise on both the cycloergometer and the treadmill. Blood lactate was similar during exercise on both ergometers for all groups. These results suggest that the quantitative effects of training on cardiovascular and respiratory functions may only be properly evaluated by using an ergometer which requires an activity similar to that usually performed by the subjects. Cycle riding may possibly induce significant and specific alterations in the muscles involved in the exercise, thus increasing peripheral O2 uptake even after stabilization of maximal cardiac output, whereas running may well induce an improvement of all factors which are responsible for aerobic work power. PMID:6518340

  20. Molecular Mechanisms Mediating the Adaptive Regulation of Intestinal Riboflavin Uptake Process

    PubMed Central

    Subramanian, Veedamali S.; Ghosal, Abhisek; Kapadia, Rubina; Nabokina, Svetlana M.; Said, Hamid M.

    2015-01-01

    The intestinal absorption process of vitamin B2 (riboflavin, RF) is carrier-mediated, and all three known human RF transporters, i.e., hRFVT-1, -2, and -3 (products of the SLC52A1, 2 & 3 genes, respectively) are expressed in the gut. We have previously shown that the intestinal RF uptake process is adaptively regulated by substrate level, but little is known about the molecular mechanism(s) involved. Using human intestinal epithelial NCM460 cells maintained under RF deficient and over-supplemented (OS) conditions, we now show that the induction in RF uptake in RF deficiency is associated with an increase in expression of the hRFVT-2 & -3 (but not hRFVT-1) at the protein and mRNA levels. Focusing on hRFVT-3, the predominant transporter in the intestine, we also observed an increase in the level of expression of its hnRNA and activity of its promoter in the RF deficiency state. An increase in the level of expression of the nuclear factor Sp1 (which is important for activity of the SLC52A3 promoter) was observed in RF deficiency, while mutating the Sp1/GC site in the SLC52A3 promoter drastically decreased the level of induction in SLC52A3 promoter activity in RF deficiency. We also observed specific epigenetic changes in the SLC52A3 promoter in RF deficiency. Finally, an increase in hRFVT-3 protein expression at the cell surface was observed in RF deficiency. Results of these investigations show, for the first time, that transcriptional and post-transcriptional mechanisms are involved in the adaptive regulation of intestinal RF uptake by the prevailing substrate level. PMID:26121134

  1. Carrier-mediated uptake of nobiletin, a citrus polymethoxyflavonoid, in human intestinal Caco-2 cells.

    PubMed

    Kimura, Osamu; Ohta, Chiho; Koga, Nobuyuki; Haraguchi, Koichi; Kato, Yoshihisa; Endo, Tetsuya

    2014-07-01

    The mechanism of intestinal absorption of nobiletin (NBL) was investigated using Caco-2 cells. The uptake of NBL from the apical membranes of Caco-2 cells was rapid and temperature-dependent and the presence of metabolic inhibitors, NaN3 and carbonylcyanide p-trifluoromethoxyphenylhydrazone, did not cause a decrease in NBL uptake. The relationship between the initial uptake of NBL and its concentration was saturable, suggesting the involvement of a carrier-mediated process. The Km and uptake clearance (Vmax/Km) values for NBL were 50.6 and 168.1μl/mg protein/min, respectively. This clearance value was about 9-fold greater than that of the non-saturable uptake clearance (Kd: 18.5μl/mg protein/min). The presence of structurally similar compounds, such as quercetin and luteolin, competitively inhibited NBL uptake. These results suggest that uptake of NBL from the apical membranes of Caco-2 cells is mainly mediated by an energy-independent facilitated diffusion process. PMID:24518326

  2. Involvement of intestinal uptake transporters in the absorption of azithromycin and clarithromycin in the rat.

    PubMed

    Garver, Eric; Hugger, Erin D; Shearn, Shawn P; Rao, Anuradha; Dawson, Paul A; Davis, Charles B; Han, Chao

    2008-12-01

    Macrolide antibiotics azithromycin (AZI) and clarithromycin (CLARI) are large molecular weight compounds and are substrates for apically polarized efflux transporters such as P-glycoprotein, which can potentially restrict intestinal absorption. However, despite these undesired physicochemical and biopharmaceutical properties, AZI and CLARI exhibit moderate to excellent p.o. bioavailability in preclinical species and humans. Intestinal uptake transporters, such as organic anion transporting polypeptides (OATPs), can facilitate the uptake of drugs that are substrates and hence increase p.o. absorption. The present study was designed to determine whether the intestinal Oatps are involved in absorption of these macrolides. AZI or CLARI was dosed p.o. to Sprague-Dawley rats after p.o. administration with vehicle or rifamycin SV (RIF), an OATP inhibitor. The p.o. exposures of AZI and CLARI were reduced 65 and 45%, respectively, when coadministered with an optimized RIF regimen. The p.o. RIF had no affect on the total blood clearance of these macrolides and most likely did not cause induction of metabolizing enzymes and/or transporters. Therefore, the results suggest that inhibition of an RIF-sensitive uptake transporter such as Oatp along the rat gastrointestinal tract was responsible for reduced p.o. exposure of AZI and CLARI. In addition, AZI and CLARI caused inhibition of taurocholate uptake in rat Oatp1a5-transfected Madin-Darby canine kidney cell monolayers. The in vitro and in vivo results suggest that the intestinal Oatps are involved in the p.o. absorption of AZI and CLARI in the rat. PMID:18755851

  3. Role of iron in the intestinal uptake of cadmium in the newborn rat

    SciTech Connect

    Leon, L.

    1983-01-01

    There is evidence that suckling rats have a greater capacity for intestinal transport of heavy metals than do mature animals. It has been suggested that iron transport mechanisms provide a way for non-essential metals like Cd to be absorbed. The effect of iron on intestinal uptake of cadmium (/sup 109/Cd) was investigated in suckling (14 day old), adolescent (28 day old) and young adult rats (42 day old) using an in situ incubation technique. In the presence of 0.4 and 2.0 mM Fe SO/sub 4/, intestinal uptake of Cd was significantly decreased in 14 day old pups. When dams and pups were placed on an iron deficient diet (ID) tissue iron levels decreased in 28 and 42 day old rats but not in 14 day old rats. The results of the present studies suggest that intestinal cadmium transport in the suckling, adolescent and young adult rat is mediated, at least in part, by iron transport pathways.

  4. Critical evaluation of oxygen-uptake assessment in swimming.

    PubMed

    Sousa, Ana; Figueiredo, Pedro; Pendergast, David; Kjendlie, Per-Ludvik; Vilas-Boas, João P; Fernandes, Ricardo J

    2014-03-01

    Swimming has become an important area of sport science research since the 1970s, with the bioenergetic factors assuming a fundamental performance-influencing role. The purpose of this study was to conduct a critical evaluation of the literature concerning oxygen-uptake (VO2) assessment in swimming, by describing the equipment and methods used and emphasizing the recent works conducted in ecological conditions. Particularly in swimming, due to the inherent technical constraints imposed by swimming in a water environment, assessment of VO2max was not accomplished until the 1960s. Later, the development of automated portable measurement devices allowed VO2max to be assessed more easily, even in ecological swimming conditions, but few studies have been conducted in swimming-pool conditions with portable breath-by-breath telemetric systems. An inverse relationship exists between the velocity corresponding to VO2max and the time a swimmer can sustain it at this velocity. The energy cost of swimming varies according to its association with velocity variability. As, in the end, the supply of oxygen (whose limitation may be due to central-O2 delivery and transportation to the working muscles-or peripheral factors-O2 diffusion and utilization in the muscles) is one of the critical factors that determine swimming performance, VO2 kinetics and its maximal values are critical in understanding swimmers' behavior in competition and to develop efficient training programs. PMID:24414133

  5. The interrelationship between muscle oxygenation, muscle activation, and pulmonary oxygen uptake to incremental ramp exercise: influence of aerobic fitness.

    PubMed

    Boone, Jan; Barstow, Thomas J; Celie, Bert; Prieur, Fabrice; Bourgois, Jan

    2016-01-01

    We investigated whether muscle and ventilatory responses to incremental ramp exercise would be influenced by aerobic fitness status by means of a cross-sectional study with a large subject population. Sixty-four male students (age: 21.2 ± 3.2 years) with a heterogeneous peak oxygen uptake (51.9 ± 6.3 mL·min(-1)·kg(-1), range 39.7-66.2 mL·min(-1)·kg(-1)) performed an incremental ramp cycle test (20-35 W·min(-1)) to exhaustion. Breath-by-breath gas exchange was recorded, and muscle activation and oxygenation were measured with surface electromyography and near-infrared spectroscopy, respectively. The integrated electromyography (iEMG), mean power frequency (MPF), deoxygenated [hemoglobin and myoglobin] (deoxy[Hb+Mb]), and total[Hb+Mb] responses were set out as functions of work rate and fitted with a double linear function. The respiratory compensation point (RCP) was compared and correlated with the breakpoints (BPs) (as percentage of peak oxygen uptake) in muscle activation and oxygenation. The BP in total[Hb+Mb] (83.2% ± 3.0% peak oxygen uptake) preceded (P < 0.001) the BP in iEMG (86.7% ± 4.0% peak oxygen uptake) and MPF (86.3% ± 4.1% peak oxygen uptake), which in turn preceded (P < 0.01) the BP in deoxy[Hb+Mb] (88.2% ± 4.5% peak oxygen uptake) and RCP (87.4% ± 4.5% peak oxygen uptake). Furthermore, the peak oxygen uptake was significantly (P < 0.001) positively correlated to the BPs and RCP, indicating that the BPs in total[Hb+Mb] (r = 0.66; P < 0.001), deoxy[Hb+Mb] (r = 0.76; P < 0.001), iEMG (r = 0.61; P < 0.001), MPF (r = 0.63; P < 0.001), and RCP (r = 0.75; P < 0.001) occurred at a higher percentage of peak oxygen uptake in subjects with a higher peak oxygen uptake. In this study a close relationship between muscle oxygenation, activation, and pulmonary oxygen uptake was found, occurring in a cascade of events. In subjects with a higher aerobic fitness level this cascade occurred at a higher relative intensity. PMID:26701120

  6. Increased sediment oxygen uptake caused by oxygenation-induced hypolimnetic mixing.

    PubMed

    Bryant, Lee D; Gantzer, Paul A; Little, John C

    2011-06-01

    Hypolimnetic oxygenation systems (HOx) are increasingly used in lakes and reservoirs to elevate dissolved oxygen (O(2)) while preserving stratification, thereby decreasing concentrations of reduced chemical species in the hypolimnion. By maintaining an oxic zone in the upper sediment, HOx suppress fluxes of reduced soluble species from the sediment into the overlying water. However, diminished HOx performance has been observed due to HOx-induced increases in sediment O(2) uptake. Based on a series of in situ O(2) microprofile and current velocity measurements, this study evaluates the vertical O(2) distribution at the sediment-water interface as a function of HOx operation. These data were used to determine how sediment O(2) uptake rate (JO2) and sediment oxic-zone depth (z(max)) were affected by applied oxygen-gas flow rate, changes in near-sediment mixing and O(2) concentration, and proximity to the HOx. The vertical sediment-water O(2) distribution was found to be strongly influenced by oxygenation on a reservoir-wide basis. Elevated JO2 and an oxic sediment zone were maintained during continuous HOx operation, with z(max) increasing linearly with HOx flow rate. In contrast, JO2 decreased to zero and the sediment became anoxic as the vertical O(2) distribution at the sediment-water interface collapsed during periods when the HOx was turned off and near-sediment mixing and O(2) concentrations decreased. JO2 and z(max) throughout the reservoir were found to be largely governed by HOx-induced mixing rather than O(2) levels in the water column. By quantifying how JO2 and z(max) vary in response to HOx operations, this work (1) characterizes how hypolimnetic oxygenation affects sediment O(2) dynamics, (2) contributes to the optimization of water quality and management of HOx-equipped lakes and reservoirs, and (3) enhances understanding of the effect of mixing and O(2) concentrations in other systems. PMID:21565379

  7. Estimating peak oxygen uptake based on postexercise measurements in swimming.

    PubMed

    Chaverri, Diego; Iglesias, Xavier; Schuller, Thorsten; Hoffmann, Uwe; Rodríguez, Ferran A

    2016-06-01

    To assess the validity of postexercise measurements in estimating peak oxygen uptake (V̇O2peak) in swimming, we compared oxygen uptake (V̇O2) measurements during supramaximal exercise with various commonly adopted methods, including a recently developed heart rate - V̇O2 modelling procedure. Thirty-one elite swimmers performed a 200-m maximal swim where V̇O2 was measured breath-by-breath using a portable gas analyzer connected to a respiratory snorkel, 1 min before, during, and 3 min postexercise. V̇O2peak(-20-0) was the average of the last 20 s of effort. The following postexercise measures were compared: (i) first 20-s average (V̇O2peak(0-20)); (ii) linear backward extrapolation (BE) of the first 20 s (BE(20)), 30 s, and 3 × 20-, 4 × 20-, and 3 or 4 × 20-s averages; (iii) semilogarithmic BE at 20 s (LOG(20)) and at the other same time intervals as in linear BE; and (iv) predicted V̇O2peak using mathematical modelling (pV̇O2(0-20)]. Repeated-measures ANOVA and post-hoc Bonferroni tests compared V̇O2peak (criterion) and each estimated value. Pearson's coefficient of determination (r(2)) was used to assess correlation. Exercise V̇O2peak(-20-0) (mean ± SD 3531 ± 738 mL·min(-1)) was not different (p > 0.30) from pV̇O2(0-20) (3571 ± 735 mL·min(-1)), BE(20) (3617 ± 708 mL·min(-1)), or LOG(20) (3627 ± 746 mL·min(-1)). pV̇O2(0-20) was very strongly correlated with exercise V̇O2peak (r(2) = 0.962; p < 0.001), and showed a low standard error of the estimate (146 mL·min(-1), 4.1%) and the lowest mean difference (40 mL·min(-1); 1.1%). We confirm that the new modelling procedure based on postexercise V̇O2 and heart rate measurements is a valid and accurate procedure for estimating V̇O2peak in swimmers and avoids the estimation bias produced by other methods. PMID:27226382

  8. Influence of sodium on major diffusion barriers to passive intestinal uptake.

    PubMed

    Thomson, A B

    1982-08-01

    Intestinal active transport processes have been shown to be sodium dependent, but the effect of varying the concentration of sodium in the luminal bulk phase on the passive uptake of lipids has not been established. An in vitro technique was used to measure the uptake of fatty acids and alcohols into the rabbit jejunum under conditions of stirring of the bulk phase selected to reduce the effective resistance of the unstirred water layer (UWL). Sodium withdrawal had no effect on the uptake of a homologous series of fatty alcohols, and thus the UWL was not influenced by varying bulk-phase sodium; in contrast, the uptake of a homologous series of short-, medium, and long-chain-length saturated fatty acids (FA) was progressively inhibited by reducing bulk-phase sodium from 145 to 0 meq/l. There was no difference in FA uptake between the use of magnesium chloride and mannitol for maintenance of isotonicity with sodium withdrawal. At each sodium concentration, the uptake of FA rose with increasing FA chain length. The relation between sodium concentration and incremental change in free energy (delta delta Fw leads to 1) was described by a sigmoid-shaped curve. The uptake of cholesterol was also inhibited by reducing sodium in the bulk phase. In summary, varying bulk-phase sodium has no effect on UWL, and the influence of sodium on the uptake of FA is mediated by altering delta delta Fw leads to 1 and therefore the physicochemical properties of the brush-border membrane. PMID:7114222

  9. Intestinal zinc uptake in freshwater rainbow trout: evidence for apical pathways associated with potassium efflux and modified by calcium.

    PubMed

    Glover, Chris N; Bury, Nicolas R; Hogstrand, Christer

    2004-05-27

    Understanding the mechanisms of intestinal zinc uptake in fish is of considerable interest from both nutritional and toxicological perspectives. In this study, properties of zinc transport across the apical membrane of freshwater rainbow trout intestinal epithelia were examined using right-side-out brush border membrane vesicles (BBMV's). Extravesicular calcium was found to have complex actions on zinc uptake. At a low zinc concentration of 1 microM, calcium (0.1-2 mM) significantly stimulated zinc uptake. In contrast, calcium inhibited zinc uptake at higher zinc levels (100 microM). Lanthanum and cadmium in the external medium did not block zinc uptake, suggesting that interactions between zinc and calcium were not exerted at a calcium channel. Copper also failed to exercise any inhibitory action. Zinc association with the BBMV's was enhanced by an outward potassium gradient. This stimulatory effect was only present at a zinc concentration of 100 microM. The potassium channel blocker, tetraethylammonium chloride inhibited zinc uptake at this relatively high zinc concentration, suggesting the presence of a low affinity zinc uptake pathway linked to potassium efflux. The present study provides evidence that the mechanism of intestinal zinc uptake in rainbow trout is pharmacologically very different from that of the piscine gill and the mammalian intestine. PMID:15157623

  10. Reduction in peak oxygen uptake after prolonged bed rest

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.; Kozlowski, S.

    1982-01-01

    The hypothesis that the magnitude of the reduction in peak oxygen uptake (VO2) after bed rest is directly proportional to the level of pre-bed rest peak VO2 is tested. Complete pre and post-bed rest working capacity and body weight data were obtained from studies involving 24 men (19-24 years old) and 8 women (23-34 years old) who underwent bed rest for 14-20 days with no remedial treatments. Results of regression analyses of the present change in post-bed rest peak VO2 on pre-bed rest peak VO2 with 32 subjects show correlation coefficients of -0.03 (NS) for data expressed in 1/min and -0.17 for data expressed in ml/min-kg. In addition, significant correlations are found that support the hypothesis only when peak VO2 data are analyzed separately from studies that utilized the cycle ergometer, particularly with subjects in the supine position, as opposed to data obtained from treadmill peak VO2 tests. It is concluded that orthostatic factors, associated with the upright body position and relatively high levels of physical fitness from endurance training, appear to increase the variability of pre and particularly post-bed rest peak VO2 data, which would lead to rejection of the hypothesis.

  11. Pulmonary Oxygen Uptake Kinetics During Exercise in Subclinical Hypothyroidism

    PubMed Central

    Coelho, Emerson Filipino; de Lima, Jorge Roberto Perrout; Laterza, Mateus Camaroti; Barral, Marselha Marques; Teixeira, Patrícia de Fátima dos Santos; Vaisman, Mário

    2014-01-01

    Background: Patients with subclinical hypothyroidism (SCH) have lower exercise tolerance, but the impact on oxygen uptake (VO2) kinetics is unknown. This study evaluated VO2 kinetics during and after a constant load submaximal exercise in SCH. Methods: The study included 19 women with SCH (thyrotropin (TSH)=6.87±2.88 μIU/mL, free thyroxine (fT4)=0.97±0.15 ng/dL) and 19 controls (TSH=2.29±0.86 μIU/mL, T4=0.99±0.11 ng/dL) aged between 20 and 55 years. Ergospirometry exercise testing was performed for six minutes with a constant load of 50 W, followed by six minutes of passive recovery. The VO2 kinetics was quantified by the mean response time (MRT), which is the exponential time constant and approximates the time needed to reach 63% of change in VO2 (ΔVO2). The O2 deficit—energy supplied by anaerobic metabolism at the onset of exercise—and O2 debit—extra energy demand during the recovery period—were calculated by the formula MRT×ΔVO2. Values are mean±standard deviation. Results: In the rest-exercise transition, patients with SCH showed slower VO2 kinetics (MRT=47±8 sec vs. 40±6 sec, p=0.004) and a higher oxygen deficit (580±102 mL vs. 477±95 mL, p=0.003) than controls respectively. In the exercise-recovery transition, patients with SCH also showed slower VO2 kinetics (MRT=54±6 sec vs. 44±6 sec, p=0.001) and a higher oxygen debit (679±105 mL vs. 572±104 mL, p=0.003). The VO2 kinetics showed a significant correlation with TSH (p<0.05). Conclusions: This study demonstrates that women with SCH have the slowest VO2 kinetics in the onset and recovery of a constant-load submaximal exercise and highlights that this impairment is already manifest in the early stage of the disease. PMID:24512502

  12. Transport and uptake effects of marine complex lipid liposomes in small intestinal epithelial cell models.

    PubMed

    Du, Lei; Yang, Yu-Hong; Xu, Jie; Wang, Yu-Ming; Xue, Chang-Hu; Kurihara, Hideyuki; Takahashi, Koretaro

    2016-04-20

    Nowadays, marine complex lipids, including starfish phospholipids (SFP) and cerebrosides (SFC) separated from Asterias amurensis as well as sea cucumber phospholipids (SCP) and cerebrosides (SCC) isolated from Cucumaria frondosa, have received much attention because of their potent biological activities. However, little information is known on the transport and uptake of these lipids in liposome forms in small intestinal cells. Therefore, this study was undertaken to investigate the effects of these complex lipid liposomes on transport and uptake in Caco-2 and M cell monolayer models. The results revealed that SFP and SCP contained 42% and 47.9% eicosapentaenoic acid (EPA), respectively. The average particle sizes of liposomes prepared in this study were from 169 to 189 nm. We found that the transport of the liposomes across the M cell monolayer model was much higher than the Caco-2 cell monolayer model. The liposomes consisting of SFP or SCP showed significantly higher transport and uptake than soy phospholipid (soy-PL) liposomes in both Caco-2 and M cell monolayer models. Our results also exhibited that treatment with 1 mM liposomes composed of SFP or SCP for 3 h tended to increase the EPA content in phospholipid fractions of both differentiated Caco-2 and M cells. Moreover, it was also found that the hybrid liposomes consisting of SFP/SFC/cholesterol (Chol) revealed higher transport and uptake across the M cell monolayer in comparison with other liposomes. Furthermore, treatment with SFP/SFC/Chol liposomes could notably decrease the trans-epithelial electrical resistance (TEER) values of Caco-2 and M cell monolayers. The present data also showed that the cell viability of differentiated Caco-2 and M cells was not affected after the treatment with marine complex lipids or soy-PL liposomes. Based on the data in this study, it was suggested that marine complex lipid liposomes exhibit prominent transport and uptake in small intestinal epithelial cell models. PMID

  13. Dependence of intestinal amino acid uptake on dietary protein or amino acid levels

    SciTech Connect

    Karasov, W.H.; Solberg, D.H.; Diamond, J.M.

    1987-05-01

    To understand how intestinal amino acid (AA) transport is regulated by dietary substrate levels, the authors measured uptake of seven radioactively-labelled AAs and glucose across the jejunal brush-border membrane of mice kept on one of three isocaloric rations differing in nitrogen content. In the high-protein ration, uptake increased by 77-81% for the nonessential, less toxic AAs, proline, and aspartate but only by 32-61% for the more toxic essential AAs tested. In the nitrogen-deficient ration, uptake decreased for the nonessential aspartate and proline but stayed constant or increased for essential AAs and for the nonessential alanine. These patterns imply independent regulation of the intestine's various AA transporters. With decreasing dietary AA (or protein), the imino acid and acidic AA private transporters are repressed, while activities of the basic AA transporter and the neutral AA public transporter decrease to an asymptote or else go through a minimum. These regulatory patterns can be understood as a compromise among conflicting constraints imposed by protein's multiple roles as a source of calories, nitrogen, and essential AAs and by the toxicity of essential AAs at high concentrations.

  14. Effects of xylitol on carbohydrate digesting enzymes activity, intestinal glucose absorption and muscle glucose uptake: a multi-mode study.

    PubMed

    Chukwuma, Chika Ifeanyi; Islam, Md Shahidul

    2015-03-01

    The present study investigated the possible mechanism(s) behind the effects of xylitol on carbohydrate digesting enzymes activity, muscle glucose uptake and intestinal glucose absorption using in vitro, ex vivo and in vivo experimental models. The effects of increasing concentrations of xylitol (2.5%-40% or 164.31 mM-2628.99 mM) on alpha amylase and alpha glucosidase activity in vitro and intestinal glucose absorption and muscle glucose uptake were investigated under ex vivo conditions. Additionally, the effects of an oral bolus dose of xylitol (1 g per kg BW) on gastric emptying and intestinal glucose absorption and digesta transit in the different segments of the intestinal tract were investigated in normal and type 2 diabetic rats at 1 hour after dose administration, when phenol red was used as a recovery marker. Xylitol exhibited concentration-dependent inhibition of alpha amylase (IC₅₀ = 1364.04 mM) and alpha glucosidase (IC₅₀ = 1127.52 mM) activity in vitro and small intestinal glucose absorption under ex vivo condition. Xylitol also increased dose dependent muscle glucose uptake with and without insulin, although the uptake was not significantly affected by the addition of insulin. Oral single bolus dose of xylitol significantly delayed gastric emptying, inhibited intestinal glucose absorption but increased the intestinal digesta transit rate in both normal and diabetic rats compared to their respective controls. The data of this study suggest that xylitol reduces intestinal glucose absorption via inhibiting major carbohydrate digesting enzymes, slowing gastric emptying and fastening the intestinal transit rate, but increases muscle glucose uptake in normal and type 2 diabetic rats. PMID:25656339

  15. Characteristics of pancreatic cholesterol esterase binding to and uptake by rat intestinal cells

    SciTech Connect

    Wright Wiesenfeld, P.L.

    1988-01-01

    In the intestinal lumen cholesterol esterase derived from pancreatic juice catalyzes the hydrolysis of cholesteryl esters (CE). The characteristics of Ce'ase binding to and uptake by rat intestinal cells were determined. CE'ase purified from rat pancreas with a specific activity 2 fold higher and a yield 5 fold greater than that previously attainable was judged as homogeneous on the basis of SDS-PAGE and sedimentation equilibrium centrifugation. Intestinal cell types and membranes were isolated and judged as pure on the basis of marker enzyme analyses. The enzyme was radiolabeled with ({sup 125}-I) to a specific radioactivity of 55 Ci/mmole with retention of biological activity, gross molecular size, secondary structure, and immunological properties. ({sup 125}-I) CE'ase bound preferentially to mature absorptive cells from proximal intestine and their brush border membranes. A specific, low affinity binding phenomenon was demonstrated with the following characteristics: linearity with increasing ligand concentration (non-saturability) or cell concentration, time and temperature dependency, and irreversibility. Native CE'ase, at a 500 fold molar excess did not displace bound ({sup 125}-I) CE'ase.

  16. The role of vasoactive intestinal peptide in scavenging singlet oxygen

    SciTech Connect

    Misra, B.R.; Misra, H.P. )

    1990-02-26

    The neuropeptide vasoactive intestinal peptide (VIP), a highly basic 28 amino acid peptide, has a widespread distribution in the body. The functional specificity of this peptide not only includes its potent vasodilatory activity, but also its role in protecting lungs against acute injury, in preventing T-lymphocyte proliferation and in modulating immune function. The purpose of this study was to examine the possible antioxidant properties of VIP. The authors found that VIP up to 50 {mu}g/ml had no inhibitory effect on its reduction of cytochrome C by xanthine and xanthine oxidase, indicating that the peptide does not have significant O{sub 2} scavenging ability. However, VIP was found to inhibit, in a dose-dependent manner, the {sup 1}O{sub 2} dependent 2, 2, 6, 6 tetramethyl piperidine oxide (TEMPO) formation. {sup 1}O{sub 2} was produced by rose benzal photosensitizing system and was detected as TEMP-{sup 1}O{sub 2} adduct (TEMPO) by electron paramagnetic resonance (EPR) spectroscopic technique. The formation of TEMPO signal was strongly inhibited by {beta}-carotene, histidine as well as azide, but not by superoxide dismutase (48 {mu}g/ml), catalase (20 {mu}g/ml) and mannitol (6mM), indicating that TEMPO signal was a TEMP-{sup 1}O{sub 2} adduct. These results indicate that VIP has potent antioxidant activity and may serve as a singlet O{sub 2} scavenger, thus it may modulate the oxidative tissue injury caused by this reactive oxygen species.

  17. Maximal oxygen uptake in Chilean workers of normal nutritional status.

    PubMed

    Sánchez, J; Donoso, H

    1988-01-01

    Maximum oxygen uptake (VO2max) was measured directly and predicted from cardiac frequency measurements in 54 healthy Chilean industrial workers aged 20 to 55 years, together with assessment of their dietary intake, body composition and blood chemistry. Measurement of VO2 was performed on a motor-driven treadmill. The predicted VO2max was obtained using a cycle ergometer by two methods: 1) the Astrand-Ryhming nomogram and 2) the linear relationship between "steady state" heart rate (HR) and submaximum work, with subsequent extrapolation to "maximum" heart rate. Extrapolation of the HR/load regression line to 170 bpm permitted determination of the physical working capacity at 170 bpm (W170). VO2max for the 20-29 year group (Group I) averaged 3624 ml.min-1 and decreased to 3066 ml.min-1 in the 50-55 year group (Group IV). Lower values were obtained using the Astrand-Ryhming nomogram and HR/load regression (-15% and -9% respectively). W170 was also affected by age (Group I: 190.6 W and Group IV: 158.5 W). No significant correlation were found between VO2max and plasma variables, with the exception of cholesterol (r = 0.59). On the contrary, anthropometric variables showed significant correlations with VO2max, which permitted the prediction of VO2max using multiple regression equations. The two best correlations were: 1. VO2max = 0.800 - 0.0225.(A) +0.0189.(W)+1.26.(H) (r = 0.87; p less than 0.001) 2. VO2max = 0.996 - 0.0176.(A) + 0.025.(W) + 0.838.(H) + 0.0255.(LBM) (r = 0.88; p less than 0.001) where A = years of age; W = body weight in kg; H = height in m and LBM = lean body mass in kg. PMID:3342789

  18. Reduced Oxygen Uptake Efficiency Slope in Patients with Cardiac Sarcoidosis

    PubMed Central

    Ammenwerth, Wilhelm; Wurps, Henrik; Klemens, Mark A.; Crolow, Catharina; Schulz-Menger, Jeanette; Schönfeld, Nicolas; Bittner, Roland C.; Bauer, Torsten T.

    2014-01-01

    Background The non-invasive diagnosis of cardiac sarcoidosis (CS) is difficult. Cardiovascular magnetic resonance (CMR) has become a very valuable diagnostic tool in patients with suspected CS, but usually a combination of different tests is used. Oxygen uptake efficiency slope (OUES) is a parameter of cardiopulmonary exercise testing (CPET), which is used as an indicator for cardiovascular impairment. We investigated the predictive value of OUES for the diagnosis of myocardial involvement in sarcoid patients. Methods Retrospectively 37 consecutive patients (44.9±13.8 years) with histologically confirmed sarcoidosis and clinical suspicion of heart involvement underwent noninvasive diagnostic testing including CMR. CS was diagnosed according to the guidelines from the Japanese Society of Sarcoidosis and other Granulomatous Disorders with additional consideration of CMR findings. Furthermore, CPET with calculation of predicted OUES according to equations by Hollenberg et al. was carried out. Results Patients with CS (11/37; 30%) had a worse cardiovascular response to exercise. OUES was significantly lower in CS-group compared to non-CS-group (59.3±19.1 vs 88.0±15.4%pred., p<0.0001). ROC curve method identified 70%pred. as the OUES cut-off point, which maximized sensitivity and specificity for detection of CS (96% sensitivity, 82% specificity, 89% overall accuracy). OUES <70%pred. was the single best predictor of CS (Odds ratio: 100.43, 95% CI: 1.99 to 5064, p<0.001) even in multivariate analyses. Conclusion OUES assessed in CPET may be helpful in identifying patient with cardiac involvement of sarcoidosis. Patient selection for CMR may be assisted by CPET findings in patients with sarcoidosis. PMID:25029031

  19. Background Intestinal 18F-FDG Uptake Is Related to Serum Lipid Profile and Obesity in Breast Cancer Patients

    PubMed Central

    Yoon, Hai-Jeon; Kim, Han-Na; Yun, Yeojun; Kim, Yemi; Ha, Ae-Na

    2015-01-01

    Background This study investigated the relationships between background intestinal uptake on 18F–FDG PET and cardio-metabolic risk (CMR) factors. Methods A total of 326 female patients that underwent 18F–FDG PET to determine the initial stage of breast cancer were enrolled. None of the patients had history of diabetes or hypertension. The background intestinal uptake on PET was visually graded (low vs. high uptake group) and quantitatively measured using the maximal standardized uptake value (SUVmax). SUVmax of 7 bowel segments (duodenum, jejunum, ileum, cecum, hepatic flexure, splenic flexure, and descending colon-sigmoid junction) were averaged for the total bowel (TB SUVmax). Age, body mass index (BMI), fasting blood glucose level (BST), triglyceride (TG), cholesterol, high density lipoprotein (HDL), and low density lipoprotein (LDL) were the considered CMR factors. The relationships between background intestinal 18F–FDG uptake on PET and diverse CMR factors were analyzed. Results The visual grades based on background intestinal 18F–FDG uptake classified 100 (30.7%) patients into the low uptake group, while 226 (69.3%) were classified into the high uptake group. Among CMR factors, age (p = 0.004), BMI (p<0.001), and TG (p<0.001) were significantly different according to visual grade of background intestinal 18F–FDG uptake. Quantitative TB SUVmax showed significant positive correlation with age (r = 0.203, p<0.001), BMI (r = 0.373, p<0.001), TG (r = 0.338, p<0.001), cholesterol (r = 0.148, p = 0.008), and LDL (r = 0.143, p = 0.024) and significant negative correlation with HDL (r = -0.147, p = 0.022). Multivariate analysis indicated that BMI and TG were independent factors in both visually graded background intestinal 18F–FDG uptake (p = 0.027 and p = 0.023, respectively) and quantitatively measured TB SUVmax (p = 0.006 and p = 0.004, respectively). Conclusion Increased background intestinal 18F–FDG uptake on PET may suggest alteration of lipid

  20. Transcobalamin derived from bovine milk stimulates apical uptake of vitamin B12 into human intestinal epithelial cells.

    PubMed

    Hine, Brad; Boggs, Irina; Green, Ralph; Miller, Joshua W; Hovey, Russell C; Humphrey, Rex; Wheeler, Thomas T

    2014-11-01

    Intestinal uptake of vitamin B12 (hereafter B12) is impaired in a significant proportion of the human population. This impairment is due to inherited or acquired defects in the expression or function of proteins involved in the binding of diet-derived B12 and its uptake into intestinal cells. Bovine milk is an abundant source of bioavailable B12 wherein it is complexed with transcobalamin. In humans, transcobalamin functions primarily as a circulatory protein, which binds B12 following its absorption and delivers it to peripheral tissues via its cognate receptor, CD320. In the current study, the transcobalamin-B12 complex was purified from cows' milk and its ability to stimulate uptake of B12 into cultured bovine, mouse and human cell lines was assessed. Bovine milk-derived transcobalamin-B12 complex was absorbed by all cell types tested, suggesting that the uptake mechanism is conserved across species. Furthermore, the complex stimulated the uptake of B12 via the apical surface of differentiated Caco-2 human intestinal epithelial cells. These findings suggest the presence of an alternative transcobalamin-mediated uptake pathway for B12 in the human intestine other than that mediated by the gastric glycoprotein, intrinsic factor. Our findings highlight the potential for transcobalamin-B12 complex derived from bovine milk to be used as a natural bioavailable alternative to orally administered free B12 to overcome B12 malabsorption. PMID:24913691

  1. Luminal fructose inhibits rat intestinal sodium-phosphate cotransporter gene expression and phosphate uptake24

    PubMed Central

    Kirchner, Séverine; Muduli, Anjali; Casirola, Donatella; Prum, Kannitha; Douard, Véronique; Ferraris, Ronaldo P

    2008-01-01

    Background While searching by microarray for sugar-responsive genes, we inadvertently discovered that sodium-phosphate cotransporter 2B (NaPi-2b) mRNA concentrations were much lower in fructose-perfused than in glucose-perfused intestines of neonatal rats. Changes in NaPi-2b mRNA abundance by sugars were accompanied by similar changes in NaPi-2b protein abundance and in rates of inorganic phosphate (Pi) uptake. Objective We tested the hypothesis that luminal fructose regulates NaPi-2b. Design We perfused into the intestine fructose, glucose, and non-metabolizable or poorly transported glucose analogs as well as phlorizin. Results NaPi-2b mRNA concentrations and Pi uptake rates in fructose-perfused intestines were ≈30% of those in glucose and its analogs. NaPi-2b inhibition by fructose is specific because the mRNA abundance and activity of the fructose transporter GLUT5 (glucose transporter 5) increased with fructose perfusion, whereas those of other transporters were independent of the perfusate. Plasma Pi after 4 h of perfusion was independent of the perfusate, probably because normal kidneys can maintain normophosphatemia. Inhibiting glucose-6-phosphatase, another fructose-responsive gene, with tungstate or vanadate nonspecifically inhibited NaPi-2b mRNA expression and Pi uptake in both glucose- or fructose-perfused intestines. The AMP kinase (AMPK)–activator AICAR (5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside) enhanced and the fatty acid synthase–AMPK inhibitor C75 (3-carboxy-4-octyl-2-methylene-butyrolactone trans-4-carboxy-5-octyl-3-methylenebutyrolactone) prevented fructose inhibition of NaPi-2b but had no effect on expression of other transporters. NaPi-2b expression decreased markedly with age and was inhibited by fructose in all age groups. Conclusions Energy levels in enterocytes may play a role in NaPi-2b inhibition by luminal fructose. Consumption of fructose that supplies ≈10% of caloric intake by Americans clearly affects absorption of

  2. Oxygen Uptake by a Cobalt(II) Complex: An Undergraduate Experiment

    ERIC Educational Resources Information Center

    Appleton, Trevor G.

    1977-01-01

    An experimental procedure is described for studying oxygen uptake by a transition metal. This procedure is designed for use with undergraduates and may be used in organic or biochemistry laboratories. Diagrams of the apparatus are included. (MR)

  3. CONTINUOUS, AUTOMATED AND SIMULTANEOUS MEASUREMENT OF OXYGEN UPTAKE AND CARBON DIOXIDE EVOLUTION IN BIOLOGICAL SYSTEMS

    EPA Science Inventory

    Commercial respirometers are capable of continuously and automatically measuring oxygen uptake in bioreactors. A method for continuously and automatically measuring carbon dioxide evolution can be retrofitted to commercial respirometers. Continuous and automatic measurements of...

  4. Pathophysiology of intestinal uptake and absorption of antigens in food allergy.

    PubMed

    Walker, W A

    1987-11-01

    An important adaptation of the gastrointestinal tract to the extrauterine environment is its development of a mucosal barrier against the penetration of proteins and protein fragments. To combat the potential danger of invasion across the mucosal barrier, the infant must develop within the lumen and on the luminal mucosal surface an elaborate system of defense mechanisms that act to control and maintain the epithelium as an impermeable barrier to the uptake of macromolecular antigens. These defenses include a unique local immunologic system adapted to function in the complicated milieu of the intestine as well as other nonimmunologic processes such as a gastric barrier, intestinal surface secretions, peristaltic movement, etc, all of which help to provide maximum protection for the intestinal surface. Unfortunately, during the immediate postpartum period, especially for premature and "small-for-date" infants, this elaborate local defense system is incompletely developed. As a result of the delay in the maturation of the mucosal barrier, newborn infants are particularly vulnerable to pathologic penetration by harmful intraluminal substances. The consequences of altered defense are susceptibility to infection and the potential for hypersensitivity reactions and the formation of immune complexes. With these reactions comes the potential for developing life-threatening diseases such as necrotizing enterocolitis, sepsis, and hepatitis. Fortunately, nature has provided a means for passively protecting the "vulnerable" newborn against the dangers of a deficient intestinal defense system: human milk. It is now increasingly apparent that human milk contains not only antibodies and viable leukocytes, but many other substances that can interfere with bacterial colonization and prevent antigen penetration. PMID:3318588

  5. Influence of age in estimating maximal oxygen uptake

    PubMed Central

    de Souza e Silva, Christina G; Franklin, Barry A; Forman, Daniel E; Araújo, Claudio Gil S

    2016-01-01

    Objective To assess the influence of age on the error of estimate (EE) of maximal oxygen uptake (VO2max) using sex and population specific-equations in cycle ergometer exercise testing, since estimated VO2 max is associated with a substantial EE, often exceeding 20%, possibly due to intrinsic variability of mechanical efficiency. Methods 1850 adults (68% men), aged 18 to 91 years, underwent maximal cycle ergometer cardiopulmonary exercise testing. Cardiorespiratory fitness (CRF) was assessed relative to sex and age [younger (18 to 35 years), middle-aged (36 to 60 years) and older (> 60 years)]. VO2max [mL·(kg·min)−1] was directly measured by assessment of gas exchange and estimated using sex and population specific-equations. Measured and estimated values of VO2max and related EE were compared among the three age- and sex-specific groups. Results Directly measured VO2max of men and women were 29.5 ± 10.5 mL·(kg·min)−1 and 24.2 ± 9.0 mL·(kg·min)−1 (P < 0.01). EE [mL·(kg·min)−1] and percent errors (%E) for men and women had similar values, 0.5 ± 3.2 and 0.4 ± 2.9 mL·(kg·min)−1, and −0.8 ± 13.1% and −1.7 ± 15.4% (P > 0.05), respectively. EE and %E for each age-group were, respectively, for men: younger = 1.9 ± 4.1 mL·(kg·min)−1 and 3.8 ± 10.5%, middle-aged = 0.6 ± 3.1 mL·(kg·min)−1 and 0.4 ± 10.3%, older = −0.2 ± 2.7 mL·(kg·min)−1 and −4.2 ± 16.6% (P < 0.01); and for women: younger = 1.2 ± 3.1 mL·(kg·min)−1 and 2.7 ± 10.0%, middle-aged = 0.7 ± 2.8 mL·(kg·min)−1 and 0.5 ± 11.1%, older = -0.8 ± 2.3 mL·(kg·min)−1 and −9.5 ± 22.4% (P < 0.01). Conclusion VO2max were underestimated in younger age-groups and were overestimated in older age groups. Age significantly influences the magnitude of the EE of VO2max in both men and women and should be considered when CRF is estimated using population specific equations, rather than directly measured. PMID:27168737

  6. Factors influencing intestinal cadmium uptake in pregnant Bangladeshi women-A prospective cohort study

    SciTech Connect

    Kippler, M.; Goessler, W.; Nermell, B.; Ekstroem, E.C.; Loennerdal, B.; El Arifeen, S.; Vahter, M.

    2009-10-15

    Experimental studies indicate that zinc (Zn) and calcium (Ca) status, in addition to iron (Fe) status, affect gastrointestinal absorption of cadmium (Cd), an environmental pollutant that is toxic to kidneys, bone and endocrine systems. The aim of this study was to evaluate how various nutritional factors influence the uptake of Cd in women, particularly during pregnancy. The study was carried out in a rural area of Bangladesh, where malnutrition is prevalent and exposure to Cd via food appears elevated. The uptake of Cd was evaluated by associations between erythrocyte Cd concentrations (Ery-Cd), a marker of ongoing Cd exposure, and concentrations of nutritional markers. Blood samples, collected in early pregnancy and 6 months postpartum, were analyzed by inductively coupled plasma mass spectrometry (ICPMS). Ery-Cd varied considerably (range: 0.31-5.4 {mu}g/kg) with a median of 1.1 {mu}g/kg (approximately 0.5 {mu}g/L in whole blood) in early pregnancy. Ery-Cd was associated with erythrocyte manganese (Ery-Mn; positively), plasma ferritin (p-Ft; negatively), and erythrocyte Ca (Ery-Ca; negatively) in decreasing order, indicating common transporters for Cd, Fe and Mn. There was no evidence of Cd uptake via Zn transporters, but the association between Ery-Cd and p-Ft seemed to be dependent on adequate Zn status. On average, Ery-Cd increased significantly by 0.2 {mu}g/kg from early pregnancy to 6 months postpartum, apparently due to up-regulated divalent metal transporter 1 (DMT1). In conclusion, intestinal uptake of Cd appears to be influenced either directly or indirectly by several micronutrients, in particular Fe, Mn and Zn. The negative association with Ca may suggest that Cd inhibits the transport of Ca to blood.

  7. An Inexpensive Electrode and Cell for Measurement of Oxygen Uptake in Chemical and Biochemical Systems.

    ERIC Educational Resources Information Center

    Brunet, Juan E.; And Others

    1983-01-01

    The continuous measurement of oxygen consumption in an enzymatic reaction is a frequent experimental fact and extremely important in the enzymatic activity of oxygenase. An electrochemical system, based on a polarographic method, has been developed to monitor the oxygen uptake. The system developed and electrode used are described. (JN)

  8. Oxygen Uptake. Operational Control Tests for Wastewater Treatment Facilities. Instructor's Manual [and] Student Workbook.

    ERIC Educational Resources Information Center

    Wooley, John F.

    Biological waste treatment in the activated sludge process is based on the ability of microorganisms to use dissolved oxygen in breaking down soluble organic substances. The oxygen uptake test is a means of measuring the respiration rate of microorganisms in this process. Designed for individuals who have completed National Pollutant Discharge…

  9. Uptake of polypeptide fragments of proteins by rat intestine in vitro and in vivo

    SciTech Connect

    Bloch, K.J.; Wright, J.A.; Bishara, S.M.; Bloch, M.B.

    1988-11-01

    Minute amounts of intact proteins were previously shown to be taken up from the intestine into the systemic circulation of mature animals; fragments were not detected. In this study, we sought evidence for uptake of fragments in both in vitro and in vivo experiments. Polypeptide fragments produced by pepsin digestion of bovine serum albumin (ranging in molecular weight from approximately 6000 to 25,000) were labeled with /sup 125/I. Everted jejunal gut sacs prepared from rat intestine were incubated with labeled fragments. After incubation, fluid exposed to the serosal surface was applied to a Sephadex G-50 gel permeation column. Radioactivity was detected in fractions corresponding to the elution position of the fragments. Transfer of fragments from the mucosal to the serosal surface was temperature-dependent. In in vivo studies, labeled fragments were infused into the jejunum of rats. Blood samples obtained from a mesenteric vein or the portal vein contained labeled fragments. After infusion of unlabeled fragments, nanogram amounts of immunoreactive fragments were detected by radioimmunoassay of mesenteric and portal venous blood. Thus, polypeptide fragments of a potential food protein were capable of being transferred across the mucosa in vitro and in vivo. Failure to detect fragments in the systemic circulation most likely results from their rapid clearance.

  10. Impact of food components during in vitro digestion of silver nanoparticles on cellular uptake and cytotoxicity in intestinal cells.

    PubMed

    Lichtenstein, Dajana; Ebmeyer, Johanna; Knappe, Patrick; Juling, Sabine; Böhmert, Linda; Selve, Sören; Niemann, Birgit; Braeuning, Albert; Thünemann, Andreas F; Lampen, Alfonso

    2015-11-01

    Because of the rising application of nanoparticles in food and food-related products, we investigated the influence of the digestion process on the toxicity and cellular uptake of silver nanoparticles for intestinal cells. The main food components--carbohydrates, proteins and fatty acids--were implemented in an in vitro digestion process to simulate realistic conditions. Digested and undigested silver nanoparticle suspensions were used for uptake studies in the well-established Caco-2 model. Small-angle X-ray scattering was used to estimate particle core size, size distribution and stability in cell culture medium. Particles proved to be stable and showed radii from 3.6 to 16.0 nm. Undigested particles and particles digested in the presence of food components were comparably taken up by Caco-2 cells, whereas the uptake of particles digested without food components was decreased by 60%. Overall, these findings suggest that in vivo ingested poly (acrylic acid)-coated silver nanoparticles may reach the intestine in a nanoscaled form even if enclosed in a food matrix. While appropriate for studies on the uptake into intestinal cells, the Caco-2 model might be less suited for translocation studies. Moreover, we show that nanoparticle digestion protocols lacking food components may lead to misinterpretation of uptake studies and inconclusive results. PMID:26040006

  11. Cellular uptake and transcytosis of lipid-based nanoparticles across the intestinal barrier: Relevance for oral drug delivery.

    PubMed

    Neves, Ana Rute; Queiroz, Joana Fontes; Costa Lima, Sofia A; Figueiredo, Francisco; Fernandes, Rui; Reis, Salette

    2016-02-01

    Oral administration is the preferred route for drug delivery and nanosystems represent a promising tool for protection and transport of hardly soluble, chemically unstable and poorly permeable drugs through the intestinal barrier. In the present work, we have studied lipid nanoparticles cellular uptake, internalization pathways and transcytosis routes through Caco-2 cell monolayers. Both lipid nanosystems presented similar size (∼180nm) and surface charge (-30mV). Nanostructured lipid carriers showed a higher cellular uptake and permeability across the barrier, but solid lipid nanoparticles could enter cells faster than the former. The internalization of lipid nanoparticles occurs mainly through a clathrin-mediated endocytosis mechanism, although caveolae-mediated endocytosis is also involved in the uptake. Both lipid nanoparticles were able to cross the intestinal barrier by a preferential transcellular route. This work contributed to a better knowledge of the developed nanosystems for the oral delivery of a wide spectrum of drugs. PMID:26550783

  12. Hyperbaric oxygen therapy for intestinal obstruction in children: an exceptional experience in a compromised child.

    PubMed

    Ohno, Y; Kanematsu, T

    1998-10-01

    Intestinal obstruction in a 2-year-old girl with a histologically proven diagnosis of retroperitoneal yolk sac carcinoma developed after the second course of anticancer chemotherapy. Nonoperative treatment was not effective. Because the patient had fallen into a state of chemotherapy-induced myelosuppression, surgery was ruled out. Thus, hyperbaric oxygen therapy was the next treatment of choice. It was performed twice under hyperbaric oxygen conditions at 2.8 atmospheric pressure for 111 minutes. After the procedure, her general status recovered well. The air-fluid level disappeared on the radiograph, and no adverse effects were observed. Later, a surgical removal of the primary tumor was performed successfully, but an intestinal resection was not required. This is the first instance in which we performed hyperbaric oxygen therapy on a child in the management of an intestinal obstruction. Based on the successful outcome in this case, hyperbaric oxygen therapy is suggested to be a useful adjunct to nonoperative therapy for intestinal obstruction when a patient's overall state does not allow operative intervention. PMID:9802810

  13. Maximal Oxygen Uptake, Sweating and Tolerance to Exercise in the Heat

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.; Castle, B. L.; Ruff, W. K.

    1972-01-01

    The physiological mechanisms that facilitate acute acclimation to heat have not been fully elucidated, but the result is the establishment of a more efficient cardiovascular system to increase heat dissipation via increased sweating that allows the acclimated man to function with a cooler internal environment and to extend his performance. Men in good physical condition with high maximal oxygen uptakes generally acclimate to heat more rapidly and retain it longer than men in poorer condition. Also, upon first exposure trained men tolerate exercise in the heat better than untrained men. Both resting in heat and physical training in a cool environment confer only partial acclimation when first exposed to work in the heat. These observations suggest separate additive stimuli of metabolic heat from exercise and environmental heat to increase sweating during the acclimation process. However, the necessity of utilizing physical exercise during acclimation has been questioned. Bradbury et al. (1964) have concluded exercise has no effect on the course of heat acclimation since increased sweating can be induced by merely heating resting subjects. Preliminary evidence suggests there is a direct relationship between the maximal oxygen uptake and the capacity to maintain thermal regulation, particularly through the control of sweating. Since increased sweating is an important mechanism for the development of heat acclimation, and fit men have high sweat rates, it follows that upon initial exposure to exercise in the heat, men with high maximal oxygen uptakes should exhibit less strain than men with lower maximal oxygen uptakes. The purpose of this study was: (1) to determine if men with higher maximal oxygen uptakes exhibit greater tolerance than men with lower oxygen uptakes during early exposure to exercise in the heat, and (2) to investigate further the mechanism of the relationship between sweating and maximal work capacity.

  14. Iron content of ferritin modulates its uptake by intestinal epithelium: implications for co-transport of prions.

    PubMed

    Bhupanapadu Sunkesula, Solomon Raju; Luo, Xiu; Das, Dola; Singh, Ajay; Singh, Neena

    2010-01-01

    The spread of Chronic Wasting Disease (CWD) in the deer and elk population has caused serious public health concerns due to its potential to infect farm animals and humans. Like other prion disorders such a sporadic Creutzfeldt-Jakob-disease of humans and Mad Cow Disease of cattle, CWD is caused by PrP-scrapie (PrPSc), a beta-sheet rich isoform of a normal cell surface glycoprotein, the prion protein (PrPC). Since PrPSc is sufficient to cause infection and neurotoxicity if ingested by a susceptible host, it is important to understand the mechanism by which it crosses the stringent epithelial cell barrier of the small intestine. Possible mechanisms include co-transport with ferritin in ingested food and uptake by dendritic cells. Since ferritin is ubiquitously expressed and shares considerable homology among species, co-transport of PrPSc with ferritin can result in cross-species spread with deleterious consequences. We have used a combination of in vitro and in vivo models of intestinal epithelial cell barrier to understand the role of ferritin in mediating PrPSc uptake and transport. In this report, we demonstrate that PrPSc and ferritin from CWD affected deer and elk brains and scrapie from sheep resist degradation by digestive enzymes, and are transcytosed across a tight monolayer of human epithelial cells with significant efficiency. Likewise, ferritin from hamster brains is taken up by mouse intestinal epithelial cells in vivo, indicating that uptake of ferritin is not limited by species differences as described for prions. More importantly, the iron content of ferritin determines its efficiency of uptake and transport by Caco-2 cells and mouse models, providing insight into the mechanism(s) of ferritin and PrPSc uptake by intestinal epithelial cells. PMID:20429907

  15. Relating pulmonary oxygen uptake to muscle oxygen consumption at exercise onset: in vivo and in silico studies

    PubMed Central

    Lai, N.; Dash, R. K.; Nasca, M. M.; Saidel, G. M.

    2014-01-01

    Assessment of the rate of muscle oxygen consumption, UO2m, in vivo during exercise involving a large muscle mass is critical for investigating mechanisms regulating energy metabolism at exercise onset. While UO2m is technically difficult to obtain under these circumstances, pulmonary oxygen uptake, VO2p, can be readily measured and used as a proxy to UO2m. However, the quantitative relationship between VO2p and UO2m during the nonsteady phase of exercise in humans, needs to be established. A computational model of oxygen transport and utilization—based on dynamic mass balances in blood and tissue cells—was applied to quantify the dynamic relationship between model-simulated UO2m and measured VO2p during moderate (M), heavy (H), and very heavy (V) intensity exercise. In seven human subjects, VO2p and muscle oxygen saturation, StO2m, were measured with indirect calorimetry and near infrared spectroscopy (NIRS), respectively. The dynamic responses of VO2p and StO2m at each intensity were in agreement with previously published data. The response time of muscle oxygen consumption, τUO2m, estimated by direct comparison between model results and measurements of StO2m was significantly faster (P < 0.001) than that of pulmonary oxygen uptake, τVO2p, (M: 13 ± 4 vs. 65 ± 7 s; H: 13 ± 4 vs. 100 ± 24 s; V: 15 ± 5 vs. 82 ± 31 s). Thus, by taking into account the dynamics of oxygen stores in blood and tissue and determining muscle oxygen consumption from muscle oxygenation measurements, this study demonstrates a significant temporal dissociation between UO2m and VO2p at exercise onset. PMID:16636861

  16. Submaximal oxygen uptake kinetics, functional mobility, and physical activity in older adults with heart failure and reduced ejection fraction

    PubMed Central

    Hummel, Scott L; Herald, John; Alpert, Craig; Gretebeck, Kimberlee A; Champoux, Wendy S; Dengel, Donald R; Vaitkevicius, Peter V; Alexander, Neil B

    2016-01-01

    Background Submaximal oxygen uptake measures are more feasible and may better predict clinical cardiac outcomes than maximal tests in older adults with heart failure (HF). We examined relationships between maximal oxygen uptake, submaximal oxygen kinetics, functional mobility, and physical activity in older adults with HF and reduced ejection fraction. Methods Older adults with HF and reduced ejection fraction (n = 25, age 75 ± 7 years) were compared to 25 healthy age- and gender-matched controls. Assessments included a maximal treadmill test for peak oxygen uptake (VO2peak), oxygen uptake kinetics at onset of and on recovery from a submaximal treadmill test, functional mobility testing [Get Up and Go (GUG), Comfortable Gait Speed (CGS), Unipedal Stance (US)], and self-reported physical activity (PA). Results Compared to controls, HF had worse performance on GUG, CGS, and US, greater delays in submaximal oxygen uptake kinetics, and lower PA. In controls, VO2peak was more strongly associated with functional mobility and PA than submaximal oxygen uptake kinetics. In HF patients, submaximal oxygen uptake kinetics were similarly associated with GUG and CGS as VO2peak, but weakly associated with PA. Conclusions Based on their mobility performance, older HF patients with reduced ejection fraction are at risk for adverse functional outcomes. In this population, submaximal oxygen uptake measures may be equivalent to VO2 peak in predicting functional mobility, and in addition to being more feasible, may provide better insight into how aerobic function relates to mobility in older adults with HF. PMID:27594875

  17. Intestine.

    PubMed

    Smith, J M; Skeans, M A; Horslen, S P; Edwards, E B; Harper, A M; Snyder, J J; Israni, A K; Kasiske, B L

    2016-01-01

    Intestine and intestine-liver transplant plays an important role in the treatment of intestinal failure, despite decreased morbidity associated with parenteral nutrition. In 2014, 210 new patients were added to the intestine transplant waiting list. Among prevalent patients on the list at the end of 2014, 65% were waiting for an intestine transplant and 35% were waiting for an intestine-liver transplant. The pretransplant mortality rate decreased dramatically over time for all age groups. Pretransplant mortality was highest for adult candidates, at 22.1 per 100 waitlist years compared with less than 3 per 100 waitlist years for pediatric candidates, and notably higher for candidates for intestine-liver transplant than for candidates for intestine transplant without a liver. Numbers of intestine transplants without a liver increased from a low of 51 in 2013 to 67 in 2014. Intestine-liver transplants increased from a low of 44 in 2012 to 72 in 2014. Short-gut syndrome (congenital and other) was the main cause of disease leading to both intestine and intestine-liver transplant. Graft survival improved over the past decade. Patient survival was lowest for adult intestine-liver recipients and highest for pediatric intestine recipients. PMID:26755265

  18. Growth hormone enhances amino acid uptake by the human small intestine.

    PubMed Central

    Inoue, Y; Copeland, E M; Souba, W W

    1994-01-01

    OBJECTIVE: The effects of growth hormone (GH) on the luminal transport of amino acids and glucose by the human small intestine were investigated. SUMMARY BACKGROUND DATA: The anabolic effect of growth hormone administration is associated with nitrogen retention and an increase muscle strength, but the impact of growth hormone on nutrient uptake from the gut lumen has not been examined. METHODS: Twelve healthy patients received a daily subcutaneous dose of low-dose GH (0.1 mg/kg), high-dose GH (0.2 mg/kg), or no treatment (controls) for 3 days before surgery. At operation, ileum (8 patients) or jejunum (4 patients) was resected, and brush border membrane vesicles (BBMVs) were prepared by differential centrifugation. Vesicle purity was confirmed by a 16-fold enrichment of marker enzymes. The carrier-mediated transport of glutamine (System B), leucine (System L), alanine (System B), arginine (System y+), MeAIB (methyl alpha-aminoisobutyric acid [System A]), and glucose (Na(+)-dependent glucose transporter) by BBMVs was measured by a rapid mixing/filtration technique. RESULTS: Treatment with low-dose GH resulted in a statistically insignificant increase in amino acid transport rates in jejunal and ileal BBMVs. High-dose GH resulted in a generalized 20%-to 70%-stimulation of amino acid transport, whereas glucose transport was not affected. The effects of GH were similar in ileum and jejunum. Kinetic analysis of the transport of glutamine (the most abundant amino acid in the body and the principal gut fuel) and the essential amino acid leucine revealed that the increase in transport was caused by a 50% increase in carrier Vmax, consistent with an increase in the number of functional carriers in the brush border membrane. Pooled analysis of transport velocities demonstrated that total rates of amino acid uptake from the gut lumen were increased significantly by 35% in GH-treated patients. CONCLUSIONS: The ability of GH to enhance amino acid uptake from the gut lumen

  19. Central Cardiovascular Responses of Quadriplegic Subjects to Arm Exercise at Varying Levels of Oxygen Uptake.

    ERIC Educational Resources Information Center

    Figoni, Stephen F.

    The purpose of this study was to assess selected central cardiovascular functions of spinal cord injured, quadriplegic subjects at varying levels of oxygen uptake (VO sub 2). Subjects included 11 untrained, male college students with C5, C6, or C7 complete quadriplegia and 11 able-bodied reference subjects. Exercise was performed on a Monark cycle…

  20. Oxygen uptake and heart rate response of 6 standardized tennis drills.

    PubMed

    Bekraoui, Nabyl; Fargeas-Gluck, Marie-Agnès; Léger, Luc

    2012-10-01

    The purpose of this study was to compare the oxygen uptake of various on-court tennis drills. Eleven tennis players were monitored with a portable metabolic device to measure oxygen uptake of 6 different tennis drills at low and high speeds. The 6 drills were done with or without striking the ball, over half or full-width of the court, in attack or defense mode, using forehand or backhand strokes. Oxygen uptake values (mean ± SD) ranged from 33.8 ± 4.2 to 42.3 ± 5.1 mL·kg⁻¹·min⁻¹ when running at low speed on the full-width court in defense mode without striking the ball and when running at high speed on the full-width court in attack mode while striking the ball, respectively. Specific differences were observed. Attacking mode requires 6.5% more energy than defensive playing mode. Backhand strokes demand 7% more energy at low speed than forehand ones. Running and striking the ball costs 10% more energy than running without striking the ball. While striking the ball, shuttle running on half-width court costs 14% more energy than running on full-width courts. The specificity of the oxygen uptake responses obtained for these various tennis drills gives an improved representation of their energy cost and could be used to optimize training loads. PMID:22871149

  1. Prediction of Maximum Oxygen Uptake Using Both Exercise and Non-Exercise Data

    ERIC Educational Resources Information Center

    George, James D.; Paul, Samantha L.; Hyde, Annette; Bradshaw, Danielle I.; Vehrs, Pat R.; Hager, Ronald L.; Yanowitz, Frank G.

    2009-01-01

    This study sought to develop a regression model to predict maximal oxygen uptake (VO[subscript 2max]) based on submaximal treadmill exercise (EX) and non-exercise (N-EX) data involving 116 participants, ages 18-65 years. The EX data included the participants' self-selected treadmill speed (at a level grade) when exercise heart rate first reached…

  2. Operation Everest II: maximal oxygen uptake at extreme altitude.

    PubMed

    Cymerman, A; Reeves, J T; Sutton, J R; Rock, P B; Groves, B M; Malconian, M K; Young, P M; Wagner, P D; Houston, C S

    1989-05-01

    Chronic exposure to high altitude reduces maximal O2 uptake (VO2max). At extreme altitudes approaching the summit of Mt. Everest [inspiratory PO2(PIO2) = 43 Torr], mean VO2max have been determined to be 15.3 ml.kg-1.min-1 in two subjects who breathed 14% O2 at 6,300 m on Mt. Everest (West et al., J. Appl. Physiol. 54: 1188-1194, 1983). To provide a more complete description of performance near the limits of human tolerance to chronic hypoxia, we measured VO2max in volunteers in an altitude chamber before, during, and after a 40-day decompression to a barometric pressure (PB) of 240 Torr (PIO2 = 43 Torr). In five of eight subjects studied at sea level and PB of 464, 347, 289, and 240 Torr, VO2max was reduced from 4.13 to 1.17 l/min (49.1-15.3 ml.kg-1.min-1) in agreement with the prior study. Although the range decreased, the rank order among the subjects was preserved. Arterial O2 saturation at maximum effort decreased (46% by ear oximetry), but minute ventilation, respiratory frequency, and tidal volume did not. The highest minute ventilation (201 l/min BTPS) was observed at PB of 464 Torr. Arterial PCO2 in three subjects at PB of 240 Torr, at rest, and with maximum effort, averaged 10.3 and 9.6 Torr, respectively. Sustained hyperventilation was crucial to exercise performance during chronic, severe hypoxemia. VO2max was lower after altitude exposure compared with initial sea level values, indicating that exposure had not improved sea level exercise capacity. PMID:2745305

  3. Intestinal ammonia transport in freshwater and seawater acclimated rainbow trout (Oncorhynchus mykiss): evidence for a Na+ coupled uptake mechanism.

    PubMed

    Rubino, Julian G; Zimmer, Alex M; Wood, Chris M

    2015-05-01

    In vitro gut sac experiments were performed on freshwater and 60% seawater acclimated trout (Oncorhynchus mykiss) under treatments designed to discern possible mechanisms of intestinal ammonia transport. Seawater acclimation increased ammonia flux rate into the serosal saline (Jsamm) in the anterior intestine, however it did not alter Jsamm in the mid- or posterior intestine suggesting similar mechanisms of ammonia handling in freshwater and seawater fish. Both fluid transport rate (FTR) and Jsamm were inhibited in response to basolateral ouabain treatment, suggesting a linkage of ammonia uptake to active transport, possibly coupled to fluid transport processes via solvent drag. Furthermore, decreases in FTR and Jsamm caused by low Na(+) treatment indicated a Na(+) linked transport mechanism. Mucosal bumetanide (10(-4) M) had no impact on FTR, yet decreased Jsamm in the anterior and mid-intestine, suggesting NH4(+) substitution for K(+) on an apical NKCC, and at least a partial uncoupling of ammonia transport from fluid transport. Additional treatments (amiloride, 5-(N-ethyl-N-isopropyl)amiloride (EIPA), phenamil, bafilomycin, 4',6-diamidino-2-phenylindole (DAPI), high sodium) intended to disrupt alternative routes of Na(+) uptake yielded no change in FTR or Jsamm, suggesting the absence of direct competition between Na(+) and ammonia for transport. Finally, [(14)C]methylamine permeability (PMA) measurements indicated the likely presence of an intestinal Rh-mediated ammonia transport system, as increasing NH4Cl (0, 1, 5 mmol l(-1)) concentrations reduced PMA, suggesting competition for transport through Rh proteins. Overall, the data presented in this paper provide some of the first insights into mechanisms of teleost intestinal ammonia transport. PMID:25545914

  4. Multiscale model for pulmonary oxygen uptake and its application to quantify hypoxemia in hepatopulmonary syndrome.

    PubMed

    Chakraborty, Saikat; Balakotaiah, Vemuri; Bidani, Akhil

    2007-01-21

    This paper presents a novel multiscale methodology for quantitative analysis of pulmonary gas exchange. The process of oxygen uptake in the lungs is a complex multiscale process, characterized by multiple time and length scales which are coupled nonlinearly through the processes of diffusion, convection and reaction, and the overall oxygen uptake is significantly influenced by the transport and reaction rate processes at the small-scales. Based on the separation of length scales, we characterize these disparate scales by three representative ones, namely micro (red blood cell), meso (capillary and alveolus) and macro (lung). We start with the fundamental convection-diffusion-reaction (CDR) equation that quantifies transport and reaction rates at each scale and apply spatial averaging techniques to reduce the dimensionality of these models. The resultant low-dimensional models embed each scale hierarchically within the other while retaining the important parameters of the small-scales in the averaged equations, and drastically reduce the computational efforts involved in solving them. We use our multiscale model for pulmonary gas exchange to quantify the oxygen uptake abnormalities in patients with hepatopulmonary syndrome (HPS), a disease which is characterized by coupled abnormalities in multiple length scales. Based on our multiscale modeling, we suggest a strategy to stratify patients with HPS into two categories--those who are oxygen-responsive and those who are oxygen non-responsive with intractable hypoxemia. PMID:16973178

  5. The influence of thermal annealing on oxygen uptake and combustion rates of a bituminous coal char

    SciTech Connect

    Osvalda Senneca; Piero Salatino; Daniela Menghini

    2007-07-01

    The effect of thermal annealing on the combustion reactivity of a bituminous coal char has been investigated with a focus on the role of the formation of surface oxides by oxygen chemisorption. The combined use of thermogravimetric analysis and of analysis of the off-gas during isothermal combustion of char samples enabled the determination of the rate and extent of oxygen uptake along burn-off. Combustion was carried out at temperatures between 350 and 510{sup o}C. Char samples were prepared by controlled isothermal heat treatment of coal for different times (in the range between 1 s and 30 min) at different temperatures (in the range 900-2000{sup o}C). Results indicate that oxygen uptake is extensive along burn-off of chars prepared under mild heat treatment conditions. The maximum oxygen uptake is barely affected by the combustion temperature within the range of combustion conditions investigated. The severity of heat treatment has a pronounced effect on char combustion rate as well as on the extent and rate at which surface oxides are built up by oxygen chemisorption. Chars prepared under severe heat treatment conditions show negligible oxygen uptake and strongly reduced combustion rates. Altogether it appears that a close correlation can be established between the extent and the accessibility of active sites on the carbon surface and the combustion rate. Despite the investigation has been carried out at temperatures well below those of practical interest, results provide useful insight into the relationship existing between thermal annealing, formation of surface oxide and combustion reactivity which is relevant to the proper formulation of detailed kinetic models of char combustion. 31 refs., 6 figs., 1 tab.

  6. Calcium bioaccessibility and uptake by human intestinal like cells following in vitro digestion of casein phosphopeptide-calcium aggregates.

    PubMed

    Perego, Silvia; Del Favero, Elena; De Luca, Paola; Dal Piaz, Fabrizio; Fiorilli, Amelia; Cantu', Laura; Ferraretto, Anita

    2015-06-01

    Casein phosphopeptides (CPPs), derived by casein proteolysis, can bind calcium ions and keep them in solution. In vitro studies have demonstrated CPP-induced cell calcium uptake, depending on the formation of (CPP + calcium) complexes and on the degree of differentiation of the intestinal cells. With the present study, we address the persistence of the complexes and of the CPP-induced calcium uptake in intestinal like cells after the digestion process, thus examining their eligibility to serve as nutraceuticals. A calcium-preloaded CPP preparation of commercial origin (Ca-CPPs) was subjected to in vitro digestion. The evolution of the supramolecular structure of the Ca-CPP complexes was studied using laser-light and X-ray scattering. The bioactivity of the pre- and post-digestion Ca-CPPs was determined in differentiated Caco2 and HT-29 cells by video imaging experiments using Fura-2. We found that Ca-CPP aggregates keep a complex supramolecular organization upon digestion, despite getting smaller in size and increasing internal calcium dispersion. Concomitantly and most interestingly, digested Ca-CPPs clearly enhance the uptake of calcium ions, especially in Caco2 cells. In contrast, digestion depletes the ability of post-loaded decalcified-CPPs (Ca-dekCPPs), with a weaker internal structure, to induce calcium uptake. The enhanced bioactivity reached upon digestion strongly suggests a recognized role of Ca-CPPs, in the form used here, as nutraceuticals. PMID:25927875

  7. Oxygen microenvironment affects the uptake of nanoparticles in head and neck tumor cells

    NASA Astrophysics Data System (ADS)

    Chen, Eunice Y.; Hodge, Sasson; Tai, Katherine; Hou, Huagang; Khan, Nadeem; Hoopes, P. Jack; Samkoe, Kimberley S.

    2013-02-01

    Survival of head and neck cancer patients has not improved in several decades despite advances in diagnostic and therapeutic techniques. Tumor hypoxia in head and neck cancers is a critical factor that leads to poor prognosis, resistance to radiation and chemotherapies, and increased metastatic potential. Magnetic nanoparticle hyperthermia (mNPHT) is a promising therapy for hypoxic tumors because nanoparticles (NP) can be directly injected into, or targeted to, hypoxic tumor cells and exposed to alternating magnetic fields (AMF) to induce hyperthermia. Magnetic NPHT can improve therapeutic effectiveness by two modes of action: 1) direct killing of hypoxic tumor cells; and 2) increase in tumor oxygenation, which has the potential to make the tumor more susceptible to adjuvant therapies such as radiation and chemotherapy. Prior studies in breast cancer cells demonstrated that a hypoxic microenvironment diminished NP uptake in vitro; however, mNPHT with intratumoral NP injection in hypoxic tumors increased tumor oxygenation and delayed tumor growth. In this study, head and neck squamous cell carcinoma (HNSCC) cell lines were incubated in normoxic, hypoxic, and hyperoxic conditions with iron oxide NP for 4-72 hours. After incubation, the cells were analyzed for iron uptake by mass spectrometry, Prussian blue staining, and electron microscopy. In contrast to breast cancer cells, uptake of NPs was increased in hypoxic microenvironments as compared to normoxic conditions in HNSCC cells. In future studies, we will confirm the effect of the oxygen microenvironment on NP uptake and efficacy of mNPHT both in vitro and in vivo.

  8. Oxygen microenvironment affects the uptake of nanoparticles in head and neck tumor cells.

    PubMed

    Chen, Eunice Y; Hodge, Sassan; Tai, Katherine; Hou, Huagang; Khan, Nadeem; Hoopes, P Jack; Samkoe, Kimberley S

    2013-02-26

    Survival of head and neck cancer patients has not improved in several decades despite advances in diagnostic and therapeutic techniques. Tumor hypoxia in head and neck cancers is a critical factor that leads to poor prognosis, resistance to radiation and chemotherapies, and increased metastatic potential. Magnetic nanoparticle hyperthermia (mNPHT) is a promising therapy for hypoxic tumors because nanoparticles (NP) can be directly injected into, or targeted to, hypoxic tumor cells and exposed to alternating magnetic fields (AMF) to induce hyperthermia. Magnetic NPHT can improve therapeutic effectiveness by two modes of action: 1) direct killing of hypoxic tumor cells; and 2) increase in tumor oxygenation, which has the potential to make the tumor more susceptible to adjuvant therapies such as radiation and chemotherapy. Prior studies in breast cancer cells demonstrated that a hypoxic microenvironment diminished NP uptake in vitro; however, mNPHT with intratumoral NP injection in hypoxic tumors increased tumor oxygenation and delayed tumor growth. In this study, head and neck squamous cell carcinoma (HNSCC) cell lines were incubated in normoxic, hypoxic, and hyperoxic conditions with iron oxide NP for 4-72 hours. After incubation, the cells were analyzed for iron uptake by mass spectrometry, Prussian blue staining, and electron microscopy. In contrast to breast cancer cells, uptake of NPs was increased in hypoxic microenvironments as compared to normoxic conditions in HNSCC cells. In future studies, we will confirm the effect of the oxygen microenvironment on NP uptake and efficacy of mNPHT both in vitro and in vivo. PMID:25301994

  9. Variation in oxygen isotope ratio of dissolved orthophosphate induced by uptake process in natural coral holobionts

    NASA Astrophysics Data System (ADS)

    Ferrera, Charissa M.; Miyajima, Toshihiro; Watanabe, Atsushi; Umezawa, Yu; Morimoto, Naoko; San Diego-McGlone, Maria Lourdes; Nadaoka, Kazuo

    2016-06-01

    A model incubation experiment using natural zooxanthellate corals was conducted to evaluate the influence of phosphate uptake by coral holobionts on oxygen isotope ratio of dissolved PO4 3- (δ18Op). Live coral samples of Acropora digitifera, Porites cylindrica, and Heliopora coerulea were collected from coral reefs around Ishigaki Island (Okinawa, Japan) and Bolinao (northern Luzon, Philippines) and incubated for 3-5 d after acclimatization under natural light conditions with elevated concentrations of PO4 3-. Phosphate uptake by corals behaved linearly with incubation time, with uptake rate depending on temperature. δ18Op usually increased with time toward the equilibrium value with respect to oxygen isotope exchange with ambient seawater, but sometimes became higher than equilibrium value at the end of incubation. The magnitude of the isotope effect associated with uptake depended on coral species; the greatest effect was in A. digitifera and the smallest in H. coerulea. However, it varied even within samples of a single coral species, which suggests multiple uptake processes with different isotope effects operating simultaneously with varying relative contributions in the coral holobionts used. In natural environments where concentrations of PO4 3- are much lower than those used during incubation, PO4 3- is presumably turned over much faster and the δ18Op easily altered by corals and other major primary producers. This should be taken into consideration when using δ18Op as an indicator of external PO4 3- sources in coastal ecosystems.

  10. Influence of simulated weightlessness on maximal oxygen uptake of untrained rats

    NASA Technical Reports Server (NTRS)

    Overton, J. Michael; Tipton, Charles M.

    1987-01-01

    The purpose of this study was to determine the effect of hindlimb suspension on maximal oxygen uptake of rodents. Male Sprague-Dawley rats were assigned to head-down (HD) suspension, horizontal (HOZ) suspension, or cage (C) control for 6-9 days. Rats were tested for maximal oxygen uptake before and after surgical instrumentation (Doppler flow probes, carotid and jugular cannulae), and after suspension. Body weight was significantly decreased after suspension in both HD and HOZ groups, but was significantly increased in the C group. Absolute maximal O2 uptake (ml/min) was not different in the C group. However, because of their increased weight, relative maximal O2 uptake (ml/min per kg) was significantly reduced. In contrast, both relative and absolute maximal O2 uptake were significantly lower, following suspension, for the HD and HOZ groups. These preliminary results support the use of hindlimb suspension as an effective model to study the mechanism(s) of cardiovascular deconditioning.

  11. The Role of Oxygen Uptake and Scale Formation on the Embrittlement of Vanadium Alloys

    SciTech Connect

    Pint, Bruce A; Distefano, James R

    2005-01-01

    Vanadium alloys are of interest in fusion energy systems, however, their environmental durability is a major concern. Specimens of V-4Cr-4Ti were exposed to air and oxygen (10{sup 5},Pa), low pressure (10{sup -3}-10{sup -6} Pa) oxygen and high purity He environments (10{sup 5}-10{sup 1} Pa) it at 500-700 C in order to characterize the surface oxide, determine oxidation kinetics and quantify effects on mechanical properties at 25 and 600 C. At low oxygen pressures (P{sub O{sub 2}}.10{sup -5} Pa), linear reaction kinetics were measured for exposures up to 2000 hr and the data were used to develop a mathematical expression for the oxidation rate as a function of temperature and oxygen pressure. At higher pressures, linear-parabolic reaction kinetics were associated with high oxygen uptake and the formation of an external oxide layer. Room-temperature and 600 C tensile ductility was reduced by these exposures, but specimens which formed an external oxide were found to retain some tensile ductility after exposure. However, similar specimens with an external oxide that were subsequently annealed for 2000 hr at 700 C became severely embrittled demonstrating that a surface oxide will not prevent degradation of this refractory alloy. Exposures in He were performed to determine the effect of total gas pressure on oxygen uptake.

  12. Bile enhances glucose uptake, reduces permeability, and modulates effects of lectins, trypsin inhibitors and saponins on intestinal tissue.

    PubMed

    Bakke, Anne Marie; Chikwati, Elvis M; Venold, Fredrik F; Sahlmann, Christian; Holm, Halvor; Penn, Michael H; Oropeza-Moe, Marianne; Krogdahl, Åshild

    2014-02-01

    Antinutritional factors (ANFs) can disrupt digestive and other intestinal functions. ANFs in soybean meal (SBM) are implicated in proliferative and inflammatory responses in the intestine of various (functionally) monogastric animals, including Atlantic salmon (Salmo salar L.). The goal of the current study was to investigate the effect of ex vivo exposure of mid and distal intestinal tissue of salmon to soybean saponins (SAP), lectin (LEC) and Kunitz' trypsin inhibitor (KTI), singly and in combination, on epithelial function, as assessed by measuring in vitro glucose uptake pathways along a glucose concentration gradient. As solubilization of SAP in the calcium-containing Ringer's solution was problematic but resolved with the addition of a physiological concentration of bile collected from the gall bladder of salmon, an evaluation of bile effects became an added element. Results indicated that bile increased baseline glucose absorption and possibly transport, and also had a protective effect on the epithelial barrier, at least partially due to taurocholate. Compared to controls, tissues exposed to LEC+bile, KTI+bile and LEC+KTI+bile exhibited increased glucose uptake at the higher glucose concentrations, apparently due to markedly increased tissue permeability. Addition of SAP, however, attenuated the response, possibly by binding bile components. SAP+bile, also in combination with LEC and/or KTI, as well as LEC, KTI and LEC+KTI without bile often reduced transcellular glucose uptake pathways, while maintaining low tissue permeability. SAP+LEC+KTI+bile, LEC and KTI caused the most marked reductions. The distal intestine was more affected, reflecting the restriction of in vivo SBM-induced inflammatory changes to this region. PMID:24291392

  13. Effect of zinc source and picolinic acid on /sup 65/Zn uptake in an in vitro continuous-flow perfusion system for pig and poultry intestinal segments

    SciTech Connect

    Hill, D.A.; Peo, E.R. Jr.; Lewis, A.J.

    1987-10-01

    Twenty weanling pigs and fourteen 9-wk-old broiler chickens were used in three continuous-flow in vitro perfusion experiments using noneverted intestinal sacs to 1) determine differences in /sup 65/Zn absorption due to location within the intestinal tract, 2) evaluate /sup 65/Zn uptake from ZnCl/sub 2/ and Zn-methionine (ZnMet) with or without added picolinic acid (PA) in pig intestinal sacs and 3) evaluate /sup 65/Zn uptake from ZnCl/sub 2/ and ZnMet in chicken intestinal sacs. No differences in /sup 65/Zn uptake due to gut segment position were observed in the pigs. A Zn source x PA interaction was observed for /sup 65/Zn uptake into the pig gut tissue and for /sup 65/Zn uptake to the serosal side of the gut sacs. Total /sup 65/Zn absorption in the pig gut sacs from the two Zn sources was not different, but the addition of a 5 M ratio of PA to Zn depressed /sup 65/Zn absorption. No differences were observed in total /sup 65/Zn absorption or /sup 65/Zn uptake in poultry gut sac tissue. There was, however, greater uptake of /sup 65/Zn from ZnCl/sub 2/ to the serosal side of the sacs than from ZnMet. The data indicate that /sup 65/Zn from ZnCl/sub 2/ and ZnMet is similar in total absorption and that the addition of PA depresses Zn uptake.

  14. Surface-modified solid lipid nanoparticles for oral delivery of docetaxel: enhanced intestinal absorption and lymphatic uptake

    PubMed Central

    Cho, Hyun-Jong; Park, Jin Woo; Yoon, In-Soo; Kim, Dae-Duk

    2014-01-01

    Docetaxel is a potent anticancer drug, but development of an oral formulation has been hindered mainly due to its poor oral bioavailability. In this study, solid lipid nanoparticles (SLNs) surface-modified by Tween 80 or D-alpha-tocopheryl poly(ethylene glycol 1000) succinate (TPGS 1000) were prepared and evaluated in terms of their feasibility as oral delivery systems for docetaxel. Tween 80-emulsified and TPGS 1000-emulsified tristearin-based lipidic nanoparticles were prepared by a solvent-diffusion method, and their particle size distribution, zeta potential, drug loading, and particle morphology were characterized. An in vitro release study showed a sustained-release profile of docetaxel from the SLNs compared with an intravenous docetaxel formulation (Taxotere®). Tween 80-emulsified SLNs showed enhanced intestinal absorption, lymphatic uptake, and relative oral bioavailability of docetaxel compared with Taxotere in rats. These results may be attributable to the absorption-enhancing effects of the tristearin nanoparticle. Moreover, compared with Tween 80-emulsified SLNs, the intestinal absorption and relative oral bioavailability of docetaxel in rats were further improved in TPGS 1000-emulsified SLNs, probably due to better inhibition of drug efflux by TPGS 1000, along with intestinal lymphatic uptake. Taken together, it is worth noting that these surface-modified SLNs may serve as efficient oral delivery systems for docetaxel. PMID:24531717

  15. Uptake of caprolactam and its influence on growth and oxygen production of Desmodesmus quadricauda algae.

    PubMed

    Kalinová, Jana Pexová; Tříska, Jan; Vrchotová, Naděžda; Novák, Jan

    2016-06-01

    The consumption of polyamides produced from caprolactam is increasing continuously, and for that reason the danger of environmental contamination by this lactam is also rising. This study's aim was to evaluate the influence of caprolactam on the growth and oxygen production of the green alga Desmodesmus quadricauda and on caprolactam uptake by this alga. The presence of caprolactam in water was observed to cause the algae significantly to increase its oxygen production. Caprolactam concentration of 5,000 mg/L stopped algae growth after 6 days and influenced coenobia structure (seen as disappearance of pyrenoids, deformation of cells) but did not decrease the number of cells in the coenobia. Caprolactam uptake is probably passive but relatively rapid. Maximum concentration in the algae was reached after 18-24 h. PMID:26985739

  16. The effects of strenuous exercises on resting heart rate, blood pressure, and maximal oxygen uptake.

    PubMed

    Oh, Deuk-Ja; Hong, Hyeon-Ok; Lee, Bo-Ae

    2016-02-01

    The purpose of this study is to investigate the effects of strenuous exercises on resting heart rate, blood pressure, and maximal oxygen uptake. To achieve the purpose of the study, a total of 30 subjects were selected, including 15 people who performed continued regular exercises and 15 people as the control group. With regard to data processing, the IBM SPSS Statistics ver. 21.0 was used to calculate the mean and standard deviation. The difference of mean change between groups was verified through an independent t-test. As a result, there were significant differences in resting heart rate, maximal heart rate, maximal systolic blood pressure, and maximal oxygen uptake. However, the maximal systolic blood pressure was found to be an exercise-induced high blood pressure. Thus, it is thought that a risk diagnosis for it through a regular exercise stress test is necessary. PMID:26933659

  17. The effects of strenuous exercises on resting heart rate, blood pressure, and maximal oxygen uptake

    PubMed Central

    Oh, Deuk-Ja; Hong, Hyeon-Ok; Lee, Bo-Ae

    2016-01-01

    The purpose of this study is to investigate the effects of strenuous exercises on resting heart rate, blood pressure, and maximal oxygen uptake. To achieve the purpose of the study, a total of 30 subjects were selected, including 15 people who performed continued regular exercises and 15 people as the control group. With regard to data processing, the IBM SPSS Statistics ver. 21.0 was used to calculate the mean and standard deviation. The difference of mean change between groups was verified through an independent t-test. As a result, there were significant differences in resting heart rate, maximal heart rate, maximal systolic blood pressure, and maximal oxygen uptake. However, the maximal systolic blood pressure was found to be an exercise-induced high blood pressure. Thus, it is thought that a risk diagnosis for it through a regular exercise stress test is necessary. PMID:26933659

  18. The effect of dietary lipid composition on the intestinal uptake and tissue distribution of benzo[a]pyrene and phenanthrene in Atlantic salmon (Salmo salar).

    PubMed

    de Gelder, Stefan; Bakke, Marit J; Vos, Joëlle; Rasinger, Josef D; Ingebrigtsen, Kristian; Grung, Merete; Ruus, Anders; Flik, Gert; Klaren, Peter H M; Berntssen, Marc H G

    2016-01-01

    Uptake of polycyclic aromatic hydrocarbons (PAHs) across the intestine is suggested to occur in association with dietary lipids. Partial replacement of fish ingredients by vegetable ingredients in aquafeeds has led to increased levels of PAHs in marine farmed fish. We therefore investigated, intestinal uptake, tissue distribution and PAH metabolism after a single dose of (14)C-benzo[a]pyrene (BaP) or (14)C-phenanthrene (PHE) given to Atlantic salmon (Salmo salar) acclimatized to a fish oil or vegetable oil based diet. Both BaP and PHE were absorbed along the intestine. Fish oil based feed increased BaP concentration in the pyloric caeca and that of PHE in the proximal intestine. In contrast, vegetable oil increased BaP concentrations in the distal intestine. Extraction of whole body autoradiograms removed PHE-associated radiolabeling almost completely from the intestinal mucosa, but not BaP-associated radiolabeling, indicating the presence of BaP metabolites bound to cellular macromolecules. This observation correlates with the increased cyp1a expression in the proximal intestine, distal intestine and liver in the BaP exposed group. Furthermore, BaP-induced cyp1a expression was higher in the distal intestine of salmon fed fish oil compared to the vegetable oil fed group. PHE had no significant effect on cyp1a expression in any of these tissues. We conclude that dietary lipid composition affects intestinal PAH uptake. Fish oil based feed increased intestinal PAH concentrations probably due to an enhanced solubility in micelles composed of fish oil fatty acids. Increased BaP accumulation in the distal intestine of vegetable oil fed fish seems to be associated with a reduced Cyp1a-mediated BaP metabolism. PMID:26972757

  19. Head louse control by suffocation due to blocking their oxygen uptake.

    PubMed

    Al-Quraishy, Saleh; Abdel-Ghaffar, Fathy; Mehlhorn, Heinz

    2015-08-01

    The present study shows that head lice (Pediculus humanus capitis) are killed by suffocation when submersed into the anti-louse shampoo Licener®, which contains a mild shampoo component and an extract of neem seeds after their oil components had been pressed off. It is shown that the inner tracheal system becomes completely filled by the very fluid product. Within 3-10 min, oxygen uptake is prohibited and death of all thus treated lice stages occurred. PMID:25990060

  20. Impaired oxygen uptake efficiency slope and off-transient kinetics of pulmonary oxygen uptake in sickle cell anemia are associated with hemorheological abnormalities.

    PubMed

    Charlot, Keyne; Waltz, Xavier; Hedreville, Mona; Sinnapah, Stéphane; Lemonne, Nathalie; Etienne-Julan, Maryse; Soter, Valérie; Hue, Olivier; Hardy-Dessources, Marie-Dominique; Connes, Philippe

    2015-01-01

    Oxygen uptake efficiency slope (OUES) and excess post-exercise oxygen consumption (EPOC) are markers of physical fitness in the general population but have never been characterized in sickle cell anemia (SCA) where hematological and hemorheological properties are severely altered. Eight SCA patients and eleven healthy subjects (CONT) performed a submaximal incremental exercise conducted until the first ventilatory threshold (VT1). OUES was calculated from the data collected during the incremental period and EPOC parameters (amplitude [A] and time constant [τ]) were calculated from the data measured during exercise recovery. We found that OUES (p = 0.007) and A (p = 0.010) were lower, and τ (p = 0.035) was higher, in SCA patients compared to CONT subjects. OUES and τ were significantly correlated with hematocrit, red blood cell (RBC) deformability and RBC aggregates strength. Our findings suggest that both the abilities to use oxygen during exercise and to recover after a physical activity are impaired in SCA patients. This poor physical fitness seems to depend on the degree of anemia and RBC rheological alterations. PMID:25261432

  1. Adaptive regulation of human intestinal thiamine uptake by extracellular substrate level: a role for THTR-2 transcriptional regulation

    PubMed Central

    Nabokina, Svetlana M.; Subramanian, Veedamali S.; Valle, Judith E.

    2013-01-01

    The intestinal thiamine uptake process is adaptively regulated by the level of vitamin in the diet, but the molecular mechanism involved is not fully understood. Here we used the human intestinal epithelial Caco-2 cells exposed to different levels of extracellular thiamine to delineate the molecular mechanism involved. Our results showed that maintaining Caco-2 cells in a thiamine-deficient medium resulted in a specific and significant increase of [3H]thiamine uptake compared with cell exposure to a high level of thiamine (1 mM). This adaptive regulation was also associated with a higher level of mRNA expression of thiamine transporter-2 (THTR-2), but not thiamine transporter-1 (THTR-1), in the deficient condition and a higher level of promoter activity of gene encoding THTR-2 (SLC19A3). Using 5′-truncated promoter-luciferase constructs, we identified the thiamine level-responsive region in the SLC19A3 promoter to be between −77 and −29 (using transcriptional start site as +1). By means of mutational analysis, a key role for a stimulating protein-1 (SP1)/guanosine cytidine box in mediating the effect of extracellular thiamine level on SLC19A3 promoter was established. Furthermore, extracellular level of thiamine was found to affect SP1 protein expression and binding pattern to the thiamine level-responsive region of SLC19A3 promoter in Caco-2 cells as shown by Western blotting and electrophoretic mobility shift assay analysis, respectively. These studies demonstrate that the human intestinal thiamine uptake is adaptively regulated by the extracellular substrate level via transcriptional regulation of the THTR-2 system, and report that SP1 transcriptional factor is involved in this regulation. PMID:23989004

  2. Effects of naphthalene on the hemoglobin concentration and oxygen uptake of daphnia magna

    SciTech Connect

    Crider, J.Y.; Wilhm, J.; Harman, H.J.

    1982-01-01

    In addition to acute testing for survival of Daphnia magna exposed to naphthalene, various physiological tests were made. Short term studies were conducted to calculate LC50 values and physiological responses. Daphnia of 24 h were fed initially 0.25 ml food/l and the pH, dissolved oxygen and temperature, conductivity, swimming movements, and the number of survivors were determined at 0, 24, and 48 h. These experiments were run at least three times and the dosage-mortality curves were determined by the use of probit and regression analyses. Physiological studies were made for concentrations of 1, 5, and 10 mg/l. Oxygen consumption of Daphnia was measured polarographically and a carboxyhemoglobin method was used to measure total hemoglobin. The hemoglobin concentrations of the treated organisms decreased from 102 nmoles/animal at 1 mg/l naphthalene to 67 nmoles/animal at 9 mg/l. Oxygen uptake decreased from 37 nmoles/animal/h at 1 mg/l to 28 nmoles/animal/h at8 mg/l. Results show that hemoglobin concentration and oxygen uptake may be useful tools in assessing water quality and its effects on the biota. (JMT)

  3. Predicting Blood Lactate Concentration and Oxygen Uptake from sEMG Data during Fatiguing Cycling Exercise.

    PubMed

    Ražanskas, Petras; Verikas, Antanas; Olsson, Charlotte; Viberg, Per-Arne

    2015-01-01

    This article presents a study of the relationship between electromyographic (EMG) signals from vastus lateralis, rectus femoris, biceps femoris and semitendinosus muscles, collected during fatiguing cycling exercises, and other physiological measurements, such as blood lactate concentration and oxygen consumption. In contrast to the usual practice of picking one particular characteristic of the signal, e.g., the median or mean frequency, multiple variables were used to obtain a thorough characterization of EMG signals in the spectral domain. Based on these variables, linear and non-linear (random forest) models were built to predict blood lactate concentration and oxygen consumption. The results showed that mean and median frequencies are sub-optimal choices for predicting these physiological quantities in dynamic exercises, as they did not exhibit significant changes over the course of our protocol and only weakly correlated with blood lactate concentration or oxygen uptake. Instead, the root mean square of the original signal and backward difference, as well as parameters describing the tails of the EMG power distribution were the most important variables for these models. Coefficients of determination ranging from R(2) = 0:77 to R(2) = 0:98 (for blood lactate) and from R(2) = 0:81 to R(2) = 0:97 (for oxygen uptake) were obtained when using random forest regressors. PMID:26295396

  4. Predicting Blood Lactate Concentration and Oxygen Uptake from sEMG Data during Fatiguing Cycling Exercise

    PubMed Central

    Ražanskas, Petras; Verikas, Antanas; Olsson, Charlotte; Viberg, Per-Arne

    2015-01-01

    This article presents a study of the relationship between electromyographic (EMG) signals from vastus lateralis, rectus femoris, biceps femoris and semitendinosus muscles, collected during fatiguing cycling exercises, and other physiological measurements, such as blood lactate concentration and oxygen consumption. In contrast to the usual practice of picking one particular characteristic of the signal, e.g., the median or mean frequency, multiple variables were used to obtain a thorough characterization of EMG signals in the spectral domain. Based on these variables, linear and non-linear (random forest) models were built to predict blood lactate concentration and oxygen consumption. The results showed that mean and median frequencies are sub-optimal choices for predicting these physiological quantities in dynamic exercises, as they did not exhibit significant changes over the course of our protocol and only weakly correlated with blood lactate concentration or oxygen uptake. Instead, the root mean square of the original signal and backward difference, as well as parameters describing the tails of the EMG power distribution were the most important variables for these models. Coefficients of determination ranging from R2=0.77 to R2=0.98 (for blood lactate) and from R2=0.81 to R2=0.97 (for oxygen uptake) were obtained when using random forest regressors. PMID:26295396

  5. Oxygen uptake during post dive recovery in a diving bird Aythya fuligula: implications for optimal foraging models.

    PubMed

    Parkes, Roland; Halsey, Lewis G; Woakes, Anthony J; Holder, Roger L; Butler, Patrick J

    2002-12-01

    The rate of oxygen uptake at the surface between dives was measured for four tufted ducks, Aythya fuligula, during bouts of foraging dives to a depth of 1.8 m. The ducks surfaced into a respirometer box after each dive so that the rate of oxygen uptake ((O(2))) could be measured. (O(2)) decreased over time at the surface and there was a particularly rapid phase of oxygen uptake for approximately the first 3s. The specific shape of the oxygen uptake curve is dependent upon the duration of the preceding dive. The uptake curve after longer dives was significantly steeper during the first 3s at the surface than after shorter dives, although (O(2)) after the first 3s was not significantly different between these two dive duration bins. Thus, the mean total oxygen uptake (V(O(2))) was higher after surface periods following longer dives. Due to the high (O(2)) during the initial part of the surface period, the curve associated with longer dives was statistically biphasic, with the point of inflection at 3.3s. The curve for shorter dives was not statistically biphasic. The birds may increase their respiratory frequency during the first 3s after longer dives, producing the increased (O(2)), which would enable the birds to resaturate their oxygen stores more rapidly in response to the increased oxygen depletion of the longer submergence time. PMID:12432016

  6. Enhanced uptake and transport of (+)-catechin and (-)-epigallocatechin gallate in niosomal formulation by human intestinal Caco-2 cells.

    PubMed

    Song, Qinxin; Li, Danhui; Zhou, Yongzhi; Yang, Jie; Yang, Wanqi; Zhou, Guohua; Wen, Jingyuan

    2014-01-01

    The aim of this study was to evaluate (+)-catechin and (-)-epigallocatechin gallate (EGCG) cellular uptake and transport across human intestinal Caco-2 cell monolayer in both the absence and presence of niosomal carrier in variable conditions. The effect of free drugs and drug-loaded niosomes on the growth of Caco-2 cells was studied. The effects of time, temperature, and concentration on drug cellular uptake in the absence or presence of its niosomal delivery systems were investigated. The intestinal epithelial membrane transport of the drug-loaded niosomes was examined using the monolayer of the human Caco-2 cells. The kinetics of transport, and the effect of temperature, adenosine triphosphate inhibitor, permeability glycoprotein inhibitor, multidrug resistance-associated protein 2 inhibitor, and the absorption enhancer on transport mechanism were investigated. It was found that the uptake of catechin, EGCG, and their niosomes by Caco-2 cells was 1.22 ± 0.16, 0.90 ± 0.14, 3.25 ± 0.37, and 1.92 ± 0.22 μg/mg protein, respectively (n=3). The apparent permeability coefficient values of catechin, EGCG, and their niosomes were 1.68 ± 0.16, 0.88 ± 0.09, 2.39 ± 0.31, and 1.42 ± 0.24 cm/second (n=3) at 37°C, respectively. The transport was temperature- and energy-dependent. The inhibitors of permeability glycoprotein and multidrug resistance-associated protein 2 and the absorption enhancer significantly enhanced the uptake amount. Compared with the free drugs, niosomal formulation significantly enhanced drug absorption. Additionally, drug-loaded niosomes exhibited stronger stability and lower toxicity. These findings showed that the oral absorption of tea flavonoids could be improved by using the novel drug delivery systems. PMID:24855353

  7. The intestinal uptake of particles and the implications for drug and antigen delivery.

    PubMed Central

    O'Hagan, D T

    1996-01-01

    A number of researchers from different scientific disciplines have independently described the uptake of a variety of particulates across the gastrointestinal tract in animal models. The reports of particle uptake are briefly reviewed and the alternative mechanisms and proposed sites of uptake are discussed. Following these observations, some researchers have exploited the phenomenon of particulate uptake by using microparticles and nanoparticles as oral delivery systems for active agents, such as drugs and vaccines. The potential use of particulate carrier systems as drug and vaccine delivery systems is also briefly discussed. PMID:8982819

  8. Oxygen convective uptakes in gas exchange cycles in early diapause pupae of Pieris brassicae.

    PubMed

    Jõgar, Katrin; Kuusik, Aare; Ploomi, Angela; Metspalu, Luule; Williams, Ingrid; Hiiesaar, Külli; Kivimägi, Irja; Mänd, Marika; Tasa, Tea; Luik, Anne

    2011-09-01

    Oxygen convective uptakes in gas exchange cycles were directly recorded in early diapause pupae of Pieris brassicae L. (Lepidoptera; Pieridae) by means of O2 coulometric respirometry. This method was combined with flow-through CO2 respirometry, the two systems being switchable one to the other. During recording with both systems, measurements were also taken with infrared actography. The pupae displayed short discontinuous gas exchange cycles lasting 40-70 min. No true C phase was found by flow-through measurements; instead, flutter opening of the spiracles with discrete convective O2 uptakes began shortly after the O phase whereas CO2 release was suppressed by the inward directed passive suction ventilation. The F phase was characterized by a series of small CO2 bursts (flutter events). Between these bursts, novel sub-phase `miniflutter' was observed, which consisted of six to 10 miniature inspirations without any CO2 emission. During the flow-through measurements, oxygen convective uptakes were indirectly recorded by the infrared actograph as sudden extensions (lengthening) of the abdominal segments at each spiracular microopening. PMID:21832124

  9. Transcriptomic Analysis of Compromise Between Air-Breathing and Nutrient Uptake of Posterior Intestine in Loach (Misgurnus anguillicaudatus), an Air-Breathing Fish.

    PubMed

    Huang, Songqian; Cao, Xiaojuan; Tian, Xianchang

    2016-08-01

    Dojo loach (Misgurnus anguillicaudatus) is an air-breathing fish species by using its posterior intestine to breathe on water surface. So far, the molecular mechanism about accessory air-breathing in fish is seldom addressed. Five cDNA libraries were constructed here for loach posterior intestines form T01 (the initial stage group), T02 (mid-stage of normal group), T03 (end stage of normal group), T04 (mid-stage of air-breathing inhibited group), and T05 (the end stage of air-breathing inhibited group) and subjected to perform RNA-seq to compare their transcriptomic profilings. A total of 92,962 unigenes were assembled, while 37,905 (40.77 %) unigenes were successfully annotated. 2298, 1091, and 3275 differentially expressed genes (fn1, ACE, EGFR, Pxdn, SDF, HIF, VEGF, SLC2A1, SLC5A8 etc.) were observed in T04/T02, T05/T03, and T05/T04, respectively. Expression levels of many genes associated with air-breathing and nutrient uptake varied significantly between normal and intestinal air-breathing inhibited group. Intraepithelial capillaries in posterior intestines of loaches from T05 were broken, while red blood cells were enriched at the surface of intestinal epithelial lining with 241 ± 39 cells per millimeter. There were periodic acid-schiff (PAS)-positive epithelial mucous cells in posterior intestines from both normal and air-breathing inhibited groups. Results obtained here suggested an overlap of air-breathing and nutrient uptake function of posterior intestine in loach. Intestinal air-breathing inhibition in loach would influence the posterior intestine's nutrient uptake ability and endothelial capillary structure stability. This study will contribute to our understanding on the molecular regulatory mechanisms of intestinal air-breathing in loach. PMID:27457889

  10. Effects of glutamine and hyperoxia on pulmonary oxygen uptake and muscle deoxygenation kinetics.

    PubMed

    Marwood, Simon; Bowtell, Joanna L

    2007-01-01

    The aim of the present study was to determine whether glutamine ingestion, which has been shown to enhance the exercise-induced increase in the tricarboxylic acid intermediate (TCAi) pool size, resulted in augmentation of the rate of increase in oxidative metabolism at the onset of exercise. In addition, the potential interaction with oxygen availability was investigated by completing exercise in both normoxic and hyperoxic conditions. Eight male cyclists cycled for 6 min at 70% VO2max following consumption of a drink (5 ml kg body mass(-1)) containing a placebo or 0.125 g kg body mass(-1) of glutamine in normoxic (CON and GLN respectively) and hyperoxic (HYP and HPG respectively) conditions. Breath-by-breath pulmonary oxygen uptake and continuous, non-invasive muscle deoxygenation (via near infrared spectroscopy: NIRS) data were collected throughout exercise. The time constant of the phase II component of pulmonary oxygen uptake kinetics was unchanged between trials (CON: 21.5 +/- 3.0 vs. GLN: 18.2 +/- 1.3 vs. HYP: 18.9 +/- 2.0 vs. HPG: 18.6 +/- 1.2 s). There was also no alteration of the kinetics of relative muscle deoxygenation as measured via NIRS (CON: 5.9 +/- 0.7 vs. GLN: 7.3 +/- 0.8 vs. HYP: 6.5 +/- 0.9 vs. HPG: 5.2 +/- 0.4 s). Conversely, the mean response time of pulmonary oxygen uptake kinetics was faster (CON: 33.4 +/- 1.2 vs. GLN: 29.8 +/- 2.3 vs. HYP: 33.2 +/- 2.6 vs. HPG: 31.6 +/- 2.6 s) and the time at which muscle deoxygenation increased above pre-exercise values was earlier (CON: 9.6 +/- 0.9 vs. GLN: 8.7 +/- 1.1 vs. HYP: 8.5 +/- 0.8 vs. HPG: 8.4 +/- 0.7 s) following glutamine ingestion. In normoxic conditions, plasma lactate concentration was lower following glutamine ingestion compared to placebo. Whilst the results of the present study provide some support for the present hypothesis, the lack of any alteration in the time constant of pulmonary oxygen uptake and muscle deoxygenation kinetics suggest that the normal exercise induced expansion of

  11. Resiniferatoxin and piperine: capsaicin-like stimulators of oxygen uptake in the perfused rat hindlimb.

    PubMed

    Eldershaw, T P; Colquhoun, E Q; Bennett, K L; Dora, K A; Clark, M G

    1994-01-01

    The naturally occurring capsaicin-like molecules, resiniferatoxin (RTX, Euphorbia spp.) and piperine (Piper nigrum), each stimulated oxygen uptake (VO2) in association with increased vascular resistance in a concentration-dependent manner when infused into the perfused rat hindlimb. 5 microM glyceryl trinitrate (GTN, a nitrovasodilator) significantly blocked the oxygen and pressure responses to both RTX and piperine, indicating a close relationship between changes in VO2 and the vasoconstriction. Concentrations greater than those required for maximal VO2 resulted in an inhibition of VO2, although perfusion pressure continued to increase. Time course studies showed that both RTX and piperine at high doses resulted in a tri-phasic response. An initial phase of transient VO2 stimulation was followed by a second phase of inhibition. A third phase involving an often larger but transient stimulation of VO2 followed removal of the agents and continued after the pressure returned to basal. The actions of RTX and piperine were similar to those of other active capsaicin-like molecules tested previously in this system, including capsaicinoids (Capsicum spp.), gingerols (Zingiber officinale), and shogoals (Zingiber officinale). RTX was the most potent, and piperine the least potent of this series. Although receptor involvement has yet to be unequivocally established, the data are consistent with the presence of a functional capsaicin-like (vanilloid) receptor in the vasculature of the rat hindlimb that mediates vasoconstriction and oxygen uptake. These findings may have implications for the future development of thermogenic agents. PMID:8035653

  12. Effects of acute hypoxia on the oxygen uptake kinetics of older adults during cycling exercise.

    PubMed

    Zerbini, Livio; Brighenti, Alfredo; Pellegrini, Barbara; Bortolan, Lorenzo; Antonetti, Tommaso; Schena, Federico

    2012-08-01

    Pulmonary oxygen uptake, heart rate (HR), and deoxyhemoglobin (HHb) kinetics were studied in a group of older adults exercising in hypoxic conditions. Fourteen healthy older adults (aged 66 ± 6 years) performed 4 exercise sessions that consisted of (i) an incremental test to exhaustion on a cycloergometer while breathing normoxic room air (fractional inspired oxygen (FiO(2)) = 20.9% O(2)); (ii) an incremental test to exhaustion on a cycloergometer while breathing hypoxic room air (FiO(2) = 15% O(2)); (iii) 3 repeated square wave cycling exercises at moderate intensity while breathing normoxic room air; and (iv) 3 repeated square wave cycling exercises at moderate intensity while breathing hypoxic room air. During all exercise sessions, pulmonary gas exchange was measured breath-by-breath; HHb was determined on the vastus lateralis muscle by near-infrared spectroscopy; and HR was collected beat-by-beat. The pulomary oxygen uptake kinetics became slower in hypoxia (31 ± 9 s) than in normoxia (27 ± 7 s) because of an increased mismatching between O(2) delivery to O(2) utilization at the level of the muscle. The HR and HHb kinetics did not change between hypoxia and normoxia. PMID:22680339

  13. Oxygen uptake kinetics of constant-load work - Upright vs. supine exercise

    NASA Technical Reports Server (NTRS)

    Convertino, V. A.; Goldwater, D. J.; Sandler, H.

    1984-01-01

    Supine and upright positions were used in a comparitive study of the effects of constant load exercise on oxygen uptake (VO2), O2 deficit, steady-state VO2 and VO2 following recovery from constant load work. Ten male subjects (36-40 yr.) performed one submaximal exercise test in the supine and one test in the upright position consisting of 5 min rest and 5 min cycle ergometer exercise at 700 kg/min followed by ten minutes of recovery. It is found that the significant difference in VO2 kinetics during exercise in the upright compared to supine position resulted from changes in oxygen transport and utilization mechanisms rather than changes in mechanical efficiency. To the extent that data measured in the supine position can be used to estimate physiological responses to zero gravity, it is suggested that limitation of systemic O2 consumption may be the result of slow rates of oxygen uptake during transient periods of muscular work. Significant reductions in the rate of steady-state VO2 attainment at submaximal work intensities may produce an onset of muscle fatigue and exhaustion.

  14. Understanding low uptake of mass treatment for intestinal schistosomiasis among school children: a qualitative study in Jinja district, Uganda.

    PubMed

    Muhumuza, Simon; Olsen, Annette; Nuwaha, Fred; Katahoire, Anne

    2015-07-01

    Despite attempts to control intestinal schistosomiasis through school-based mass drug administration (MDA) with praziquantel using school teachers in Uganda, less than 30% of the school children take the treatment in some areas. The aim of the study was to understand why the uptake of praziquantel among school children is low and to suggest strategies for improved uptake. This was a cross-sectional qualitative study in which 24 focus group discussions and 15 key informant interviews were conducted 2 months after MDA. The focus group discussions were held with school children in twelve primary schools and the key informant interviews were held with school teachers, sub-county health assistants and the District Vector Control Officer. The study shows that the low uptake of praziquantel among school children is a result of a complex interplay between individual, interpersonal, institutional, community and public policy factors. The individual and interpersonal factors underpinning the low uptake include inadequate information about schistosomiasis prevention, beliefs and attitudes in the community about treatment of schistosomiasis and shared concerns among children and teachers about the side-effects of praziquantel, especially when the drug is taken on an empty stomach. The institutional, policy and community factors include inadequate preparation and facilitation of teachers and the school feeding policy, which requires parents to take responsibility for providing their children with food while at school, yet many parents cannot meet the cost of a daily meal due to the prevailing poverty in the area. It is concluded that strategies to improve uptake of praziquantel among school children need to be multi-pronged addressing not only the preparation and motivation of teachers and health education for children, but also the economic and political aspects of drug distribution, including the school feeding policy. PMID:24735860

  15. Noninvasive monitoring of small intestinal oxygen in a rat model of chronic mesenteric ischemia

    PubMed Central

    Fisher, Elaine M.; Khan, Mahmood; Salisbury, Ronald; Kuppusamy, Periannan

    2013-01-01

    We noninvasively monitored the partial pressure of oxygen (pO2) in rat small intestine using a model of chronic mesenteric ischemia by electron paramagnetic resonance oximetry (EPR) over a 7-day period. The particulate probe lithium octa-n-butoxynaphthalocyanine (LiNc-BuO) was embedded into the oxygen permeable material polydimethyl siloxane (PDMS) by cast-molding and polymerization (Oxy-Chip). A one-time surgical procedure was performed to place the Oxy-Chip on the outer wall of the small intestine (SI). The superior mesenteric artery (SMA) was banded to approximately 30% blood flow for experimental rats. Noninvasive measurement of pO2 was performed at baseline for control rats or immediate post-banding and on days 1, 3, and 7. The SI pO2 for control rats remained stable over the 7-day period. The pO2 on day 7 was 54.5 ± 0.9 mmHg (mean ± SE). SMA banded rats were significantly different from controls with a noted reduction in pO2 post banding with a progressive decline to a final pO2 of 20.9 ± 4.5 mmHg (mean ± SE; p = 0.02). All SMA-banded rats developed adhesions around the Oxy-Chip yet remained asymptomatic. The hypoxia marker Hypoxyprobe™ was used to validate low tissue pO2. Brown cytoplasmic staining was consistent with hypoxia. Mild brown staining was noted predominantly on the villus tips in control animals. SMA-banded rats had an extended region of hypoxic involvement in the villus with a higher intensity of cytoplasmic staining. Deep brown staining of the enteric nervous system neurons and connective tissue both within layers and in the mesentery were noted. SMA banded rats with lower pO2 values had a higher intensity of staining. Thus, monitoring SI pO2 using the probe Oxy-Chip provides a valid measure of tissue oxygenation. Tracking pO2 in conditions that produce chronic mesenteric ischemia will contribute to our understanding of intestinal tissue oxygenation and how changes impact symptom evolution and the trajectory of chronic disease. PMID

  16. Fermentation process using specific oxygen uptake rates as a process control

    SciTech Connect

    Van Hoek, Pim; Aristidou, Aristos; Rush, Brian

    2011-05-10

    Specific oxygen uptake (OUR) is used as a process control parameter in fermentation processes. OUR is determined during at least the production phase of a fermentation process, and process parameters are adjusted to maintain the OUR within desired ranges. The invention is particularly applicable when the fermentation is conducted using a microorganism having a natural PDC pathway that has been disrupted so that it no longer functions. Microorganisms of this sort often produce poorly under strictly anaerobic conditions. Microaeration controlled by monitoring OUR allows the performance of the microorganism to be optimized.

  17. Fermentation process using specific oxygen uptake rates as a process control

    SciTech Connect

    Van Hoek; Pim , Aristidou; Aristos , Rush; Brian

    2007-06-19

    Specific oxygen uptake (OUR) is used as a process control parameter in fermentation processes. OUR is determined during at least the production phase of a fermentation process, and process parameters are adjusted to maintain the OUR within desired ranges. The invention is particularly applicable when the fermentation is conducted using a microorganism having a natural PDC pathway that has been disrupted so that it no longer functions. Microorganisms of this sort often produce poorly under strictly anaerobic conditions. Microaeration controlled by monitoring OUR allows the performance of the microorganism to be optimized.

  18. Fermentation process using specific oxygen uptake rates as a process control

    SciTech Connect

    Van Hoek, Pim; Aristidou, Aristos; Rush, Brian

    2014-09-09

    Specific oxygen uptake (OUR) is used as a process control parameter in fermentation processes. OUR is determined during at least the production phase of a fermentation process, and process parameters are adjusted to maintain the OUR within desired ranges. The invention is particularly applicable when the fermentation is conducted using a microorganism having a natural PDC pathway that has been disrupted so that it no longer functions. Microorganisms of this sort often produce poorly under strictly anaerobic conditions. Microaeration controlled by monitoring OUR allows the performance of the microorganism to be optimized.

  19. Fermentation process using specific oxygen uptake rates as a process control

    DOEpatents

    Van Hoek, Pim; Aristidou, Aristos; Rush, Brian J.

    2016-08-30

    Specific oxygen uptake (OUR) is used as a process control parameter in fermentation processes. OUR is determined during at least the production phase of a fermentation process, and process parameters are adjusted to maintain the OUR within desired ranges. The invention is particularly applicable when the fermentation is conducted using a microorganism having a natural PDC pathway that has been disrupted so that it no longer functions. Microorganisms of this sort often produce poorly under strictly anaerobic conditions. Microaeration controlled by monitoring OUR allows the performance of the microorganism to be optimized.

  20. Does apical membrane GLUT2 have a role in intestinal glucose uptake?

    PubMed Central

    Naftalin, Richard J

    2014-01-01

    It has been proposed that the non-saturable component of intestinal glucose absorption, apparent following prolonged exposure to high intraluminal glucose concentrations, is mediated via the low affinity glucose and fructose transporter, GLUT2, upregulated within the small intestinal apical border. The evidence that the non-saturable transport component is mediated via an apical membrane sugar transporter is that it is inhibited by phloretin, after exposure to phloridzin. Since the other apical membrane sugar transporter, GLUT5, is insensitive to inhibition by either cytochalasin B, or phloretin, GLUT2 was deduced to be the low affinity sugar transport route. As in its uninhibited state, polarized intestinal glucose absorption depends both on coupled entry of glucose and sodium across the brush border membrane and on the enterocyte cytosolic glucose concentration exceeding that in both luminal and submucosal interstitial fluids, upregulation of GLUT2 within the intestinal brush border will usually stimulate downhill glucose reflux to the intestinal lumen from the enterocytes; thereby reducing, rather than enhancing net glucose absorption across the luminal surface. These states are simulated with a computer model generating solutions to the differential equations for glucose, Na and water flows between luminal, cell, interstitial and capillary compartments. The model demonstrates that uphill glucose transport via SGLT1 into enterocytes, when short-circuited by any passive glucose carrier in the apical membrane, such as GLUT2, will reduce transcellular glucose absorption and thereby lead to increased paracellular flow. The model also illustrates that apical GLUT2 may usefully act as an osmoregulator to prevent excessive enterocyte volume change with altered luminal glucose concentrations. PMID:25671087

  1. In vitro intestinal lead uptake and transport in relation to speciation.

    PubMed

    Oomen, A G; Tolls, J; Sips, A J A M; Groten, J P

    2003-01-01

    Children might be exposed substantially to contaminants such as lead via soil ingestion. In risk assessment of soil contaminants there is a need for information on oral bioavailability of soilborne lead. Oral bioavailability can be seen as the result of four steps: (1) soil ingestion; (2) mobilization from soil during digestion, i.e., bioaccessibility; (3) transport across the intestinal epithelium; and (4) first-pass effect. Lead bioaccessibility and speciation in artificial human small intestinal fluid, i.e., chyme, have been investigated in previous studies. In the present study, transport of bioaccessible lead across the intestinal epithelium was investigated using the Caco-2 cell line. Cell monolayers were exposed to (diluted) artificial chyme. In 24 h, approximately 27% of the lead were associated to the cells and 3% were transported across the cell monolayer, without signs of approaching equilibrium. Lead associated to the cells showed a linear relationship with the total amount of lead in the system. Bile levels did not affect the fraction of lead associated to Caco-2 cells. Extrapolation of the lead flux across the Caco-2 monolayer to the in vivo situation indicates that only a fraction of the bioaccessible lead is transported across the intestinal epithelium. Furthermore, the results indicate that as the free Pb(2+) concentration in chyme was negligible, lead species other than the free metal ion must have contributed to the lead flux toward the cells. On the basis of lead speciation in chyme, this can be attributed to dissociation of labile lead species, such as lead phosphate and lead bile complexes, and subsequent transport of the released free metal ions toward the intestinal membrane. PMID:12434226

  2. Effects of carbohydrate on the internal oxygen concentration, oxygen uptake, and nitrogenase activity in detached pea nodules

    SciTech Connect

    Monroe, J.D. ); LaRue, T.A. )

    1989-10-01

    The interaction between carbon substrates and O{sub 2} and their effects on nitrogenase activity (C{sub 2}H{sub 2}) were examined in detached nodules of pea (Pisum sativum L. cv Sparkle). The internal O{sub 2} concentration was estimated from the fractional oxygenation of leghemoglobin measured by reflectance spectroscopy. Lowering the endogenous carbohydrate content of nodules by excising the shoots 16 hours before nodule harvest or by incubating detached nodules at 100 kPa O{sub 2} for 2 hours resulted in a 2- to 10-fold increase in internal O{sub 2}, and a decline in nitrogenase activity. Conversely, when detached nodules were supplied with 100 millimolar succinate, the internal O{sub 2} was lowered. Nitrogenase activity was stimulated by succinate but only at high external O{sub 2}. Oxygen uptake increased linearly with external O{sub 2} but was affected only slightly by the carbon treatments. The apparent diffusion resistance in the nodule cortex was similar in all of the treatments. Carbon substrates can thus affect nitrogenase activity indirectly by affecting the O{sub 2} concentration within detached nodules.

  3. Combustion, respiration and intermittent exercise: a theoretical perspective on oxygen uptake and energy expenditure.

    PubMed

    Scott, Christopher B

    2014-01-01

    While no doubt thought about for thousands of years, it was Antoine Lavoisier in the late 18th century who is largely credited with the first "modern" investigations of biological energy exchanges. From Lavoisier's work with combustion and respiration a scientific trend emerges that extends to the present day: the world gains a credible working hypothesis but validity goes missing, often for some time, until later confirmed using proper measures. This theme is applied to glucose/glycogen metabolism where energy exchanges are depicted as conversion from one form to another and, transfer from one place to another made by both the anaerobic and aerobic biochemical pathways within working skeletal muscle, and the hypothetical quantification of these components as part of an oxygen (O2) uptake measurement. The anaerobic and aerobic energy exchange components of metabolism are represented by two different interpretations of O2 uptake: one that contains a glycolytic component (1 L O2 = 21.1 kJ) and one that does not (1 L O2 = 19.6 kJ). When energy exchange transfer and oxygen-related expenditures are applied separately to exercise and recovery periods, an increased energy cost for intermittent as compared to continuous exercise is hypothesized to be a direct result. PMID:24833508

  4. Combustion, Respiration and Intermittent Exercise: A Theoretical Perspective on Oxygen Uptake and Energy Expenditure

    PubMed Central

    Scott, Christopher B.

    2014-01-01

    While no doubt thought about for thousands of years, it was Antoine Lavoisier in the late 18th century who is largely credited with the first “modern” investigations of biological energy exchanges. From Lavoisier’s work with combustion and respiration a scientific trend emerges that extends to the present day: the world gains a credible working hypothesis but validity goes missing, often for some time, until later confirmed using proper measures. This theme is applied to glucose/glycogen metabolism where energy exchanges are depicted as conversion from one form to another and, transfer from one place to another made by both the anaerobic and aerobic biochemical pathways within working skeletal muscle, and the hypothetical quantification of these components as part of an oxygen (O2) uptake measurement. The anaerobic and aerobic energy exchange components of metabolism are represented by two different interpretations of O2 uptake: one that contains a glycolytic component (1 L O2 = 21.1 kJ) and one that does not (1 L O2 = 19.6 kJ). When energy exchange transfer and oxygen-related expenditures are applied separately to exercise and recovery periods, an increased energy cost for intermittent as compared to continuous exercise is hypothesized to be a direct result. PMID:24833508

  5. Influence of Prolonged Spaceflight on Heart Rate and Oxygen Uptake Kinetics

    NASA Astrophysics Data System (ADS)

    Hoffmann, U.; Moore, A.; Drescher, U.

    2013-02-01

    During prolonged spaceflight, physical training is used to minimize cardiovascular deconditioning. Measurement of the kinetics of cardiorespiratory parameters, in particular the kinetic analysis of heart rate, respiratory and muscular oxygen uptake, provides useful information with regard to the efficiency and regulation of the cardiorespiratory system. Practically, oxygen uptake kinetics can only be measured at the lung site (V’O2 resp). The dynamics of V’O2 resp, however, is not identical with the dynamics at the site of interest: skeletal muscle. Eight Astronauts were tested pre- and post-flight using pseudo random binary workload changes between 30 and 80 W. Their kinetic responses of heart rate, respiratory as well as muscular V’O2 kinetics were estimated by using time-series analysis. Statistical analysis revealed that the kinetic responses of respiratory as well as muscular V’O2 kinetics are slowed post-flight than pre-flight. Heart rate seems not to be influenced following flight. The influence of other factors (e. g. astronauts’ exercise training) may impact these parameters and is an area for future studies.

  6. Benthic oxygen uptake, hydrolytic potentials and microbial biomass at the Arctic continental slope

    NASA Astrophysics Data System (ADS)

    Boetius, Antje; Damm, Ellen

    1998-02-01

    Oxygen (O 2) uptake and microbial activity in sediments of the eastern Arctic continental slope were investigated in both ice-covered and ice-free areas of the Laptev Sea. Total O 2 flux ( J) decreased markedly from 2 mmol m -2 d -1 at the shelf edge (50 m) to 0.07 mmol m -2 d -1 at the bottom of the slope (3500 m), matched by the more than tenfold decline in chlorophyll pigments (CPE), protein and dissolved amino acids (DFAA). Furthermore, concentrations of these labile organic compounds were strongly correlated with extracellular enzyme potentials (EEA) in the sediments as well as with microbial biomass. The concentrations of labile substances and total microbial biomass (TMB) as well as the rates of O 2 uptake and EEA were independent of the distribution of TOC, probably due to the dominance of non-labile terrigenous compounds. Differences in O 2 uptake and microbial EEA between ice-covered and ice-free transects were relatively small. Values of O 2 uptake, CPE, EEA and TMB at the Laptev Sea slope were considerably lower than at temperate continental slopes but nevertheless higher than in the central Arctic deep-sea basin. Considering newly published data on primary productivity in the central Arctic, our results indicate that the benthic respiratory demand at the Laptev Sea slope and in the Arctic basin could be satisfied by the vertical flux of POC and does not necessarily depend on lateral advection of POC from the shelf seas as previously anticipated.

  7. First respiration estimates of cold-seep vesicomyid bivalves from in situ total oxygen uptake measurements.

    PubMed

    Decker, Carole; Caprais, Jean-Claude; Khripounoff, Alexis; Olu, Karine

    2012-04-01

    Vesicomyid bivalves are one of the most abundant symbiont-bearing species inhabiting deep-sea reducing ecosystems. Nevertheless, except for the hydrothermal vent clam Calyptogena magnifica, their metabolic rates have not been documented, and only assessed with ex situ experiments. In this study, gathering benthic chamber measurements and biomass estimation, we give the first in situ assessment of the respiration rate of these bivalves. The giant pockmark Regab, located at 3160m depth along the Congo-Angola margin, is a cold-seep site characterised by dense assemblages of two species of vesicomyids: Christineconcha regab and Laubiericoncha chuni with high dominance of C. regab. Two sites with dense aggregates of vesicomyids were selected to measure total oxygen uptake (TOU), and methane fluxes using IFREMER's benthic chamber CALMAR deployed by the ROV Quest 4000 (MARUM). Photographs were taken and bivalves were sampled using blade corers to estimate density and biomass. Total oxygen uptake was higher at Site 2 compared to Site 1 (respectively 492 mmol.m(-2).d(-1) and 332 mmol.m(-2).d(-1)). However, given vesicomyid densities and biomass, mean oxygen consumption rates were similar at both sites (1.9 to 2.5 μmol.g total dry mass(-1).h(-1) at the Site 1 and 1.8 to 2.3 μmol.g total dry mass(-1).h(-1) at Site 2). These respiration rates are higher than published ex situ estimates for cold-seep or hydrothermal vent bivalves. Although methane fluxes at the base of sulphide production were clearly higher at Site 2 (14.6 mmol.m(-2).d(-1)) than at Site 1 (0.3 mmol.m(-2).d(-1)), they do not seem to influence the respiration rates of these bivalves associated to sulphide-oxidizing symbionts. PMID:22578572

  8. In vitro micellarization and intestinal cell uptake of cis isomers of lycopene exceed those of all-trans lycopene.

    PubMed

    Failla, Mark L; Chitchumroonchokchai, Chureeporn; Ishida, Betty K

    2008-03-01

    The ratio of cis and all-trans lycopene (LYC) in human and animal tissues exceeds that in foods. The basis for this difference remains unknown, although differences in their stability, transport, and metabolism have been suggested. Here, we systematically compared the digestive stability, efficiency of micellarization, and uptake and intracellular stability of cis and all-trans isomers of LYC and carotenes using the coupled in vitro digestion and Caco-2 human intestinal cell model. Aril and oil from the carotenoid-rich gac fruit (Momordica cochinchinensis Spreng) were cooked with rice to provide a natural source of LYC and carotenes. The ratio of cis:trans isomers of LYC and beta-carotene was similar before and after simulated gastric and small intestinal digestion with recovery of total carotenoids in the digesta exceeding 70%. Micellarization of cis isomers of LYC during digestion of meals with both gac aril and oil was significantly greater than that of the all-trans isomer but less than for the carotenes. Uptake of cis isomers of LYC by Caco-2 cells was similar to that of carotenes and significantly greater than all-trans LYC. Micellarized carotenoids were relatively stable in micelles incubated in the cell culture environment and after accumulation in Caco-2 cells. These data suggest that the greater bioaccessibility of cis compared with all-trans isomers of LYC contributes to the enrichment of the cis isomers in tissues and that gac fruit is an excellent source of bioaccessible LYC and provitamin A carotenoids. PMID:18287353

  9. Polyphenols from artichoke heads (Cynara cardunculus (L.) subsp. scolymus Hayek): in vitro bio-accessibility, intestinal uptake and bioavailability.

    PubMed

    D'Antuono, Isabella; Garbetta, Antonella; Linsalata, Vito; Minervini, Fiorenza; Cardinali, Angela

    2015-04-01

    Artichoke is a rich source of health promoting compounds such as polyphenols, important for their pharmaceutical and nutritional properties. In this study, the potential for bioavailability of the artichoke polyphenols was estimated by using both in vitro digestion and Caco-2 human intestinal cell models. In vitro digestive recoveries (bio-accessibility) were found to be 55.8% for total artichoke phenolics and in particular, 70.0% for chlorogenic acid, 41.3% for 3,5-O-dicaffeoylquinic acid, and 50.3% for 1,5-O-dicaffeoylquinic acid, highlighting potential sensitivity of these compounds to gastric and small intestinal digestive conditions. Uptake of artichoke polyphenols was rapid with peak accumulation occurring after 30 min with an efficiency of 0.16%, according to the poor uptake of dietary polyphenols. Some compounds, such as coumaric acid, caffeic acid and caffeic acid derivatives, were also detected in the basolateral side assuming extra and intracellular esterase activities on chlorogenic acid. Only apigenin-7-O-glucoside was transported through the Caco-2 monolayer demonstrating its bioavailability to the extent of 1.15% at 60 min. In addition, permeability coefficient (Papp = 2.29 × 10(-5) cm s(-1)), involving apical to basolateral transport of apigenin 7-O-glucoside, was calculated to facilitate estimation of transport through the Caco-2 monolayer. Finally, the mono and dicaffeoylquinic acids present in artichoke heads exert an antioxidant activity on the human low density lipoprotein system correlated to their chemical structure. In conclusion, the utilized in vitro models, although not fully responding to the morphological and physiological features of human in vivo conditions, could be a useful tool for investigating mechanistic effects of polyphenols released from the food matrix. PMID:25758164

  10. Directed evolution to produce sludge communities with improved oxygen uptake abilities.

    PubMed

    Kunkel, Stephanie A; Pagilla, Krishna R; Stark, Benjamin C

    2015-12-01

    Two activated sludge cultures, seeded with activated sludge from the same source, were cultivated for 370 days in synthetic wastewater. Both cultures were transferred weekly to fresh medium; one culture was operated at high dissolved oxygen (DO) (near saturation) and the other at low DO (0.25 mg O2/L). There were significant changes in the abundances of bacterial species and phyla present in each culture throughout the 370-day operational period. In the low DO culture, over time, there was a continuously increasing proportion of cells of species known to encode truncated hemoglobins (Hbs). These are the types of Hbs which may enhance delivery of oxygen to the respiratory chain, to enhance ATP production, especially under low aeration conditions. The levels of heme b, the heme found in Vitreoscilla hemoglobin, increased in parallel to the increase in Hb-encoding species, to much higher levels in the low DO culture than in the high DO culture. Specific oxygen uptake rates increased by 3 % for the high DO culture near the end of the 370-day period, while those for the low DO culture increased steadily to a level 28 % higher than that of the starting culture. Thus, imposition of low DO conditions may, due to selection for Hb-expressing species, be useful in developing bacterial communities with enhanced ability to function efficiently in aerobic wastewater treatment, especially under low aeration conditions. PMID:26278534

  11. Specific oxygen uptake rate variations during batch fermentation of Bacillus thuringiensis subspecies kurstaki HD-1.

    PubMed

    Rowe, Gerald E; Margaritis, Argyrios; Wei, Ning

    2003-01-01

    The specific oxygen uptake rate (q(O)2, respiration rate) of Bacillus thuringiensis subsp. kurstaki HD-1 was very high at inoculation and was found to decrease essentially monotonically throughout both vegetative growth phase and transition phase under different batch culture conditions. Average q(O)2 values decreased from 8-10 mmol/g h at 1 h after inoculation to less than 2 mmol/g h by the time growth ended. The results are shown to be consistent with the few previous reports on q(O)2 in B. thuringiensis in the literature but also novel in that this pattern of monotonic decline has not been described previously. Both pH control and EDTA in low concentration shortened the vegetative growth phase and reduced the 10 h biomass concentration. Using plots of q(O)2 versus specific growth rate, mu, biomass yield based on the oxygen used for growth, was calculated for transition phase to be 0.041-0.047 g/mmol, consistent with literature values. The same plot also showed that the presence of EDTA resulted in an atypical q(O)2-mu trajectory and apparently much higher biomass yield from the oxygen consumed. PMID:14524704

  12. Uptake of phytodetritus by benthic foraminifera under oxygen depletion at the Indian margin (Arabian Sea)

    NASA Astrophysics Data System (ADS)

    Enge, A. J.; Witte, U.; Kucera, M.; Heinz, P.

    2014-04-01

    Benthic foraminifera in sediments on the Indian margin of the Arabian Sea, where the oxygen minimum zone (OMZ) impinges on the continental slope, are exposed to particularly severe levels of oxygen depletion. Food supply for the benthic community is high but delivered in distinct pulses during upwelling and water mixing events associated with summer and winter monsoon periods. In order to investigate the response by benthic foraminifera to such pulsed food delivery under oxygen concentrations of less than 0.1 mL L-1 (4.5 μmol L-1), an in situ isotope labeling experiment (13C, 15N) was performed on the western continental slope of India at 540 m water depth (OMZ core region). The assemblage of living foraminifera (>125 μm) in the uppermost centimeter at this depth is characterized by an unexpectedly high population density of 3982 individuals 10 cm-2 and a strong dominance by few calcareous species. For the experiment, we concentrated on the nine most abundant taxa, which constitute 93% of the entire foraminiferal population at 0-1 cm sediment depth. Increased concentrations of 13C and 15N in the cytoplasm indicate that all investigated taxa took up labeled phytodetritus during the 4 day experimental phase. In total, these nine species had assimilated 113.8 mg C m-2 (17.5% of the total added carbon). Uptake of nitrogen by the three most abundant taxa (Bolivina aff. B. dilatata, Cassidulina sp., Bulimina gibba) was 2.7 mg N m-2 (2% of the total added nitrogen). The response to the offered phytodetritus varied largely among foraminiferal species with Uvigerina schwageri being by far the most important species in short-term processing, whereas the most abundant taxa Bolivina aff. B. dilatata and Cassidulina sp. showed comparably low uptake of the offered food. We suggest the observed species-specific differences are related to species biomass and specific feeding preferences. In summary, the experiment in the OMZ core region shows rapid processing of fresh

  13. Comparative Effects of Aerobic Training and Erythropoietin on Oxygen Uptake in Untrained Humans.

    PubMed

    Sieljacks, Peter; Thams, Line; Nellemann, Birgitte; Larsen, Mads Sørensen; Vissing, Kristian; Christensen, Britt

    2016-08-01

    Sieljacks, P, Thams, L, Nellemann, B, Larsen, MS, Vissing, K, and Christensen, B. Comparative effects of aerobic training and erythropoietin on oxygen uptake in untrained humans. J Strength Cond Res 30(8): 2307-2317, 2016-The present study examines responses to 10 weeks of aerobic training and/or erythropoiesis-stimulating agent (ESA) treatment on maximal oxygen uptake (V[Combining Dot Above]O2max). Thirty-six healthy, untrained men were randomly assigned to sedentary-placebo (n = 9), sedentary-ESA (SE) (n = 9), training-placebo (TP) (n = 10), or training-ESA (TE) (n = 8). The participants were treated subcutaneously once weekly with ESA (darbepoietin-α, week 1-3; 40 μg and week 4-10; 20 μg) or a placebo for 10 weeks. The training consisted of supervised cycling 3 times per week for 1 hour at an average of 65% of maximal watt, with a progressive overload during the intervention period. V[Combining Dot Above]O2max, wattmax, and hematological values were measured throughout the study. In addition, the total training workload and estimated energy consumption were recorded after each training session. ESA treatment increased hemoglobin (∼11 and ∼14%, p < 0.001) and hematocrit (∼12 and ∼13%, p < 0.001) in the SE and TE groups, respectively. The relative (but not absolute) increases in V[Combining Dot Above]O2max were more pronounced (p < 0.01) in TE (27 ± 6%), compared with SE (15 ± 4%) but not TP (19 ± 4%), indicating that training is superior to ESA in stimulating V[Combining Dot Above]O2max in untrained men. The increased oxygen uptake in the TE group did not result in higher absolute training workloads than in the TP group. In untrained men, training exhibits a greater stimulus for improvements in V[Combining Dot Above]O2max than ESA treatment, without pronounced additive effects, which is supported by similar average training workloads and energy consumption in TP and TE. Thus, in untrained men, training alone seems sufficient to induce improvement in

  14. The uptake and accumulation of iron by the intestinal bacterium Desulfotomaculum acetoxidans DSM 771.

    PubMed

    Pado, Ryszard; Pawłowska-Cwiek, Lucyna

    2005-01-01

    Sulfate-reducing bacteria (e.g. Desulfotomaculum acetoxidans) exist in animal intestine. These bacteria are able to bind heavy metals (e.g. cadmium or lead). Comparative investigations on the composition of cellular walls of Desulfotomaculum acetoxidans--depending on the initial Fe2+ supplement in the medium (7.5, 57.5 and 507.5 M) were performed. Iron(II) was cumulated as FeS or as pyrite (FeS2). However, if the initial amount of iron was higher, its majority (46% 85%) was transported onto the membrane. It was determined that the siderophore found in Desulfotomaculum acetoxidans was deferroxamine as in animals. PMID:16212113

  15. Effects of emphysema on oxygen uptake during maximal exercise in COPD.

    PubMed

    Miniati, Massimo; Catapano, Giosuè Angelo; Monti, Simonetta; Mannucci, Francesca; Bottai, Matteo

    2013-02-01

    The objective of the study is to assess the effects of emphysema on peak oxygen uptake ([Formula: see text]) during a cardiopulmonary exercise test in patients with chronic obstructive pulmonary disease (COPD). We measured [Formula: see text] and oxygen pulse in 80 patients with stable COPD exercising maximally. Oxygen saturation was measured by pulse oximetry (SpO(2)), and the ventilatory response assessed by the ratio of tidal volume (V (T)) at peak to slow vital capacity (SVC) at baseline, and by the percent increase of peak V (T) over baseline. Computed tomography imaging (CT scan) served as the reference diagnostic standard for emphysema. Based on the panel-grading (PG) method, emphysema was rated absent or mild (PG ≤ 30, n = 54), or moderate to severe (PG > 30, n = 26). Multiple quantile regression was applied to estimate the effects of PG > 30 on [Formula: see text]. At peak exercise, the patients with PG > 30 had significantly lower [Formula: see text], oxygen pulse and SpO(2), and featured a blunted ventilatory response with respect to those with PG ≤ 30 (p < 0.001). With multiple quantile regression, the effects of PG > 30 on [Formula: see text] were only partially explained by the degree of lung hyperinflation, a substantial component being imputable to impairment of lung diffusing capacity. In conclusion, chronic obstructive pulmonary disease patients with moderate to severe emphysema feature significantly lower exercise tolerance than those with no or mild emphysema. Our findings underscore the need of tailoring therapeutic interventions for COPD to the predominant clinical phenotype to improve exercise capacity. PMID:21451988

  16. Exploring the interplay between the motivational climate and goal orientation in predicting maximal oxygen uptake.

    PubMed

    Buch, Robert; Nerstad, Christina G L; Aandstad, Anders; Säfvenbom, Reidar

    2016-01-01

    Drawing upon achievement goal theory, this study explored the interplay between the perceived motivational climate, achievement goals and objective measurements of maximal oxygen uptake (VO2max). The results of a study of 123 individuals from three Norwegian military academies revealed that under the condition of a high-performance orientation there is a stronger positive relationship between performance climate and VO2max for individuals reporting a low (rather than high)-mastery orientation. Furthermore, we found that for individuals with a high-mastery orientation there is a stronger positive relationship between mastery climate and VO2max for individuals reporting a low (rather than high)-performance orientation. These findings contribute to achievement goal theory by providing support for an interactionist person-environment fit perspective. Implications for future research and practice are discussed. PMID:25995068

  17. 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.

  18. Uptake of phytodetritus by benthic foraminifera under oxygen depletion at the Indian Margin (Arabian Sea)

    NASA Astrophysics Data System (ADS)

    Enge, A. J.; Witte, U.; Kucera, M.; Heinz, P.

    2013-09-01

    Benthic foraminifera in sediments on the Indian margin of the Arabian Sea where the oxygen minimum zone (OMZ) impinges on the continental slope are exposed to particularly severe levels of oxygen depletion. Food supply for the benthic community is high but delivered in distinct pulses during upwelling and water mixing events associated with summer and winter monsoon periods. In order to investigate the response by benthic foraminifera to such pulsed food delivery under oxygen concentrations of less than 0.1 mL L-1 (4.5 μmol L-1), an in situ isotope labeling experiment (13C, 15N) was performed at the western continental slope of India at 540 m water depth (OMZ core region). The assemblage of living foraminifera (>125 μm) in the uppermost centimeter at this depth is characterized by an unexpectedly high population density of 3982 ind. 10 cm-2 and a strong dominance by few calcareous species. For the experiment, we concentrated on the nine most abundant taxa, which constitute 93% of the entire foraminifera population at 0-1 cm sediment depth. Increased concentrations of 13C and 15N in the cytoplasm indicate that all investigated taxa took up the labeled phytodetritus during the 4 day experimental phase. In total, these nine species had assimilated 113.8 mg C m-2 (17.5% of the total added carbon). The uptake of nitrogen by the three most abundant taxa (Bolivina aff. B. dilatata, Cassidulina sp., Bulimina gibba) was 2.7 mg N m-2 (2% of the total added nitrogen) and showed the successful application of 15N as tracer in foraminiferal studies. The short-term response to the offered phytodetritus varied largely among foraminiferal species with Uvigerina schwageri being by far the most important species in short-term processing whereas the most abundant taxa Bolivina aff. B. dilatata and Cassidulina sp. showed comparably low uptake of the offered food. We suggest that the observed species-specific differences are related to individual biomass of species and to specific

  19. Ischemic preconditioning increases muscle perfusion, oxygen uptake, and force in strength-trained athletes.

    PubMed

    Paradis-Deschênes, Pénélope; Joanisse, Denis R; Billaut, François

    2016-09-01

    Muscle ischemia and reperfusion induced by ischemic preconditioning (IPC) can improve performance in various activities. However, the underlying mechanisms are still poorly understood. The purpose of this study was to examine the effects of IPC on muscle hemodynamics and oxygen (O2) uptake during repeated maximal contractions. In a cross-over, randomized, single-blind study, 10 strength-trained men performed 5 sets of 5 maximal voluntary knee extensions of the right leg on an isokinetic dynamometer, preceded by either IPC of the right lower limb (3×5-min compression/5-min reperfusion cycles at 200 mm Hg) or sham (20 mm Hg). Changes in deoxyhemoglobin, expressed as a percentage of arterial occlusion, and total hemoglobin ([THb]) concentrations of the vastus lateralis muscle were monitored continuously by near-infrared spectroscopy. Differences between IPC and sham were analyzed using Cohen's effect size (ES) ± 90% confidence limits, and magnitude-based inferences. Compared with sham, IPC likely increased muscle blood volume at rest (↑[THb], 46.5%; ES, 0.56; 90% confidence limits for ES, -0.21, 1.32). During exercise, peak force was almost certainly higher (11.8%; ES, 0.37; 0.27, 0.47), average force was very likely higher (12.6%; ES, 0.47; 0.29, 0.66), and average muscle O2 uptake was possibly increased (15.8%; ES, 0.36; -0.07, 0.79) after IPC. In the recovery periods between contractions, IPC also increased blood volume after sets 1 (23.6%; ES, 0.30; -0.05, 0.65) and 5 (25.1%; ES, 0.32; 0.09, 0.55). Three cycles of IPC immediately increased muscle perfusion and O2 uptake, conducive to higher repeated force capacity in strength-trained athletes. This maneuver therefore appears relevant to enhancing exercise training stimulus. PMID:27574913

  20. A Fast-Start Pacing Strategy Speeds Pulmonary Oxygen Uptake Kinetics and Improves Supramaximal Running Performance

    PubMed Central

    Turnes, Tiago; Salvador, Amadeo Félix; Lisbôa, Felipe Domingos; de Aguiar, Rafael Alves; Cruz, Rogério Santos de Oliveira; Caputo, Fabrizio

    2014-01-01

    The focus of the present study was to investigate the effects of a fast-start pacing strategy on running performance and pulmonary oxygen uptake () kinetics at the upper boundary of the severe-intensity domain. Eleven active male participants (28±10 years, 70±5 kg, 176±6 cm, 57±4 mL/kg/min) visited the laboratory for a series of tests that were performed until exhaustion: 1) an incremental test; 2) three laboratory test sessions performed at 95, 100 and 110% of the maximal aerobic speed; 3) two to four constant speed tests for the determination of the highest constant speed (HS) that still allowed achieving maximal oxygen uptake; and 4) an exercise based on the HS using a higher initial speed followed by a subsequent decrease. To predict equalized performance values for the constant pace, the relationship between time and distance/speed through log-log modelling was used. When a fast-start was utilized, subjects were able to cover a greater distance in a performance of similar duration in comparison with a constant-pace performance (constant pace: 670 m±22%; fast-start: 683 m±22%; P = 0.029); subjects also demonstrated a higher exercise tolerance at a similar average speed when compared with constant-pace performance (constant pace: 114 s±30%; fast-start: 125 s±26%; P = 0.037). Moreover, the mean response time was reduced after a fast start (constant pace: 22.2 s±28%; fast-start: 19.3 s±29%; P = 0.025). In conclusion, middle-distance running performances with a duration of 2–3 min are improved and response time is faster when a fast-start is adopted. PMID:25360744

  1. Uptake and transport of insulin across intestinal membrane model using trimethyl chitosan coated insulin niosomes.

    PubMed

    Moghassemi, Saeid; Parnian, Ehsan; Hakamivala, Amirhossien; Darzianiazizi, Maedeh; Vardanjani, Marzieh Mowlavi; Kashanian, Susan; Larijani, Bagher; Omidfar, Kobra

    2015-01-01

    This study reports the development of a highly stable niosomal nanostructure based on Span 60/cholesterol (CH)/N-trimethyl chitosan (TMC) system and its potential application for oral delivery of insulin. Insulin loaded niosomes were prepared by reversed-phase evaporation and TMC coating was performed by incubation of niosomal suspensions with TMC solution. The efficiency of nanoparticulate delivery system in enhancement of insulin permeation was evaluated by Caco-2 cell monolayer as intestinal membrane models. The prepared niosomes were characterized for entrapment efficiency (EE), particle size, zeta potential and stability. The particles were between 100 and 180 nm in diameter, and they were stable for over 60 days at 4 °C. Insulin permeability through Caco-2 cell monolayer was enhanced 4-fold by niosomal nanoparticles, compared with insulin alone. Further work is demanded to optimize this formulation with the object of maximizing its potential to facilitate oral delivery of insulin. PMID:25491995

  2. Pedaling rate is an important determinant of human oxygen uptake during exercise on the cycle ergometer

    PubMed Central

    Formenti, Federico; Minetti, Alberto E; Borrani, Fabio

    2015-01-01

    Estimation of human oxygen uptake () during exercise is often used as an alternative when its direct measurement is not feasible. The American College of Sports Medicine (ACSM) suggests estimating human during exercise on a cycle ergometer through an equation that considers individual's body mass and external work rate, but not pedaling rate (PR). We hypothesized that including PR in the ACSM equation would improve its prediction accuracy. Ten healthy male participants’ (age 19–48 years) were recruited and their steady-state was recorded on a cycle ergometer for 16 combinations of external work rates (0, 50, 100, and 150 W) and PR (50, 70, 90, and 110 revolutions per minute). was calculated by means of a new equation, and by the ACSM equation for comparison. Kinematic data were collected by means of an infrared 3-D motion analysis system in order to explore the mechanical determinants of . Including PR in the ACSM equation improved the accuracy for prediction of sub-maximal during exercise (mean bias 1.9 vs. 3.3 mL O2 kg−1 min−1) but it did not affect the accuracy for prediction of maximal (P > 0.05). Confirming the validity of this new equation, the results were replicated for data reported in the literature in 51 participants. We conclude that PR is an important determinant of human during cycling exercise, and it should be considered when predicting oxygen consumption. PMID:26371230

  3. Regional and systemic oxygen delivery/uptake relations and lactate flux in hyperdynamic, endotoxin-treated dogs.

    PubMed

    Curtis, S E; Cain, S M

    1992-02-01

    Pathologic oxygen supply dependency (PO2SD) may be etiologic in multisystem organ failure (MSOF) and has been related to mortality in sepsis. Although elevated lactate levels are generally assumed to be a marker of anaerobiosis in these patients, endotoxin may increase serum lactate by inactivation of pyruvate dehydrogenase (PDH), unrelated to tissue PO2. We hypothesized that regional lactate flux may correlate poorly with local oxygen delivery in sepsis. This study examined both the whole-body (WB) and regional (isolated hind limb L and gut G) responses to endotoxin infusion in terms of oxygen delivery, oxygen uptake, and lactate flux in 12 pentobarbital-anesthetized dogs. To separate hypoxia-induced lactate production from that related to inactivation of PDH by endotoxin, half the dogs received dichloroacetate (DCA), a PDH activator. After endotoxin and volume resuscitation, each animal had low systemic vascular resistance with normal to high cardiac output. Despite adequate oxygen delivery to WB, L, and G, arterial lactate levels rose significantly. A 30-min hypoxic challenge (12% FIO2) did not increase lactate levels but did increase WB O2 uptake. DCA normalized lactate levels without influencing oxygen delivery and uptake relations. These data show that lactate levels in endotoxic states may be a poor marker of tissue hypoxia and may be more related to PDH activity. PMID:1736740

  4. Hydrophobic Effect Drives Oxygen Uptake in Myoglobin via Histidine E7*

    PubMed Central

    Boechi, Leonardo; Arrar, Mehrnoosh; Martí, Marcelo A.; Olson, John S.; Roitberg, Adrián E.; Estrin, Darío A.

    2013-01-01

    Since the elucidation of the myoglobin (Mb) structure, a histidine residue on the E helix (His-E7) has been proposed to act as a gate with an open or closed conformation controlling access to the active site. Although it is believed that at low pH, the His-E7 gate is in its open conformation, the full relationship between the His-E7 protonation state, its conformation, and ligand migration in Mb is hotly debated. We used molecular dynamics simulations to first address the effect of His-E7 protonation on its conformation. We observed the expected shift from the closed to the open conformation upon protonation, but more importantly, noted a significant difference between the conformations of the two neutral histidine tautomers. We further computed free energy profiles for oxygen migration in each of the possible His-E7 states as well as in two instructive Mb mutants: Ala-E7 and Trp-E7. Our results show that even in the closed conformation, the His-E7 gate does not create a large barrier to oxygen migration and permits oxygen entry with only a small rotation of the imidazole side chain and movement of the E helix. We identify, instead, a hydrophobic site in the E7 channel that can accommodate an apolar diatomic ligand and enhances ligand uptake particularly in the open His-E7 conformation. This rate enhancement is diminished in the closed conformation. Taken together, our results provide a new conceptual framework for the histidine gate hypothesis. PMID:23297402

  5. Human intestinal transporter database: QSAR modeling and virtual profiling of drug uptake, efflux and interactions

    PubMed Central

    Sedykh, Alexander; Fourches, Denis; Duan, Jianmin; Hucke, Oliver; Garneau, Michel; Zhu, Hao; Bonneau, Pierre; Tropsha, Alexander

    2013-01-01

    Purpose Membrane transporters mediate many biological effects of chemicals and play a major role in pharmacokinetics and drug resistance. The selection of viable drug candidates among biologically active compounds requires the assessment of their transporter interaction profiles. Methods Using public sources, we have assembled and curated the largest, to our knowledge, human intestinal transporter database (>5,000 interaction entries for >3,700 molecules). This data was used to develop thoroughly validated classification Quantitative Structure-Activity Relationship (QSAR) models of transport and/or inhibition of several major transporters including MDR1, BCRP, MRP1-4, PEPT1, ASBT, OATP2B1, OCT1, and MCT1. Results & Conclusions QSAR models have been developed with advanced machine learning techniques such as Support Vector Machines, Random Forest, and k Nearest Neighbors using Dragon and MOE chemical descriptors. These models afforded high external prediction accuracies of 71–100% estimated by 5-fold external validation, and showed hit retrieval rates with up to 20-fold enrichment in the virtual screening of DrugBank compounds. The compendium of predictive QSAR models developed in this study can be used for virtual profiling of drug candidates and/or environmental agents with the optimal transporter profiles. PMID:23269503

  6. The influence of different space-related physiological variations on exercise capacity determined by oxygen uptake kinetics

    NASA Astrophysics Data System (ADS)

    Stegemann, J.

    Oxygen uptake kinetics, following defined variations of work load changes allow to estimate the contribution of aerob and anaerob energy supply which is the base for determining work capacity. Under the aspect of long duration missions with application of adequate dosed countermeasures, a reliable estimate of the astronaut's work capacity is important to adjust the necessary inflight training. Since the kinetics of oxygen uptake originate in the working muscle group itself, while measurements are performed at the mouth, various influences within the oxygen transport system might disturb the determinations. There are not only detraining effects but also well-known other influences, such as blood- and fluid shifts induced by weightlessness. They might have an impact on the circulatory system. Some of these factors have been simulated by immersion, blood donation, and changing of the body position.

  7. Exercise intensity and oxygen uptake kinetics in African-American and Caucasian women

    PubMed Central

    Lai, Nicola; Tolentino-Silva, Fatima; Nasca, Melita M.; Silva, Marco A.; Gladden, L. Bruce; Cabrera, Marco E.

    2012-01-01

    The effect of exercise intensity on the on- and off-transient kinetics of oxygen uptake (VO2) was investigated in African American (AA) and Caucasian (C) women. African American (n=7) and Caucasian (n=6) women of similar age, body mass index and weight, performed an incremental test and bouts of square-wave exercise at moderate, heavy and very heavy intensities on a cycle ergometer. Gas exchange threshold (LTGE) was lower in AA (13.6±2.3mL·kg−1min−1) than C (18.6±5.6mL·kg−1min−1). The dynamic exercise and recovery VO2 responses were characterized by mathematical models. There were no significant differences in 1) peak oxygen uptake (VO2peak) between AA (28.5±5mL kg−1min−1) and C (31.1±6.6mL kg−1min−1) and 2) VO2 kinetics at any exercise intensity. At moderate exercise, the on- and off- VO2 kinetics was described by a mono-exponential function with similar time constants τ1,on (39.4±12.5s;38.8±15s) and τ1,off (52.7±10.1s;40.7±4.4s) for AA and C, respectively. At heavy and very heavy exercise, the VO2 kinetics was described by a double-exponential function. The parameter values for heavy and very heavy exercise in the AA group were respectively: τ1,on (47.0±10.8;44.3±10s), τ2,on (289±63;219±90s), τ1,off (45.9±6.2;50.7±10s), τ2,off (259±120;243±93s) while in the C group were respectively: τ1,on (41±12;43.2±15s); τ2,on(277±81;215±36s), τ1,off (40.2±3.4;42.3±7.2s), τ2,off (215±133;228±64s). The on- and off-transients were symmetrical with respect to model order and dependent on exercise intensity regardless of race. Despite similar VO2 kinetics, LTGE and gain of the VO2 on-kinetics at moderate intensity were lower in AA than C. However, generalization to the African American and Caucasian populations is constrained by the small subject numbers. PMID:21717119

  8. Hydraulic Permeability of Resorcinol-Formaldehyde Ion-Exchange Resin - Effects of Oxygen Uptake and Radiation

    SciTech Connect

    Taylor, Paul Allen

    2009-01-01

    An ion-exchange process, using spherical resorcinol-formaldehyde (RF) resin is the baseline process for removing cesium from the dissolved salt solution in the high-level waste tanks at the U.S. Department of Energy's (DOE) Hanford site in Washington State. The RF resin is also being evaluated for use in the proposed Small Column Ion Exchange (SCIX) system, which is an alternative treatment option at DOE's Savannah River Site (SRS)in South Carolina. Testing at ORNL will determine the impact of radiation exposure and oxygen uptake by the RF resin on the hydraulic permeability of the resin. Samples of the resin will be removed periodically to measure physical properties (bead size and compressibility) and cesium capacity. The proposed full-scale treatment system at Hanford, the Waste Treatment Plant (WTP), will use an ion-exchange column containing nominally 680 gal of resin, which will treat 30 gpm of waste solution. The ion-exchange column is designed for a typical pressure drop of 6 psig, with a maximum of 9.7 psig. The lab-scale column is 3-in. clear PVC pipe and is prototypic of the proposed Hanford column. The fluid velocity in the lab-scale test will be much higher than for the full-scale column, in order to generate the maximum pressure drop expected in that column (9.7 psig). The frictional drag from this high velocity will produce similar forces on the resin in the lab-scale column as would be expected at the bottom of the full-scale column. The chemical changes in the resin caused by radiation exposure and oxygen uptake are expected to cause physical changes in the resin that could reduce the bed porosity and reduce the hydraulic permeability of the resin bed. These changes will be monitored by measuring the pressure drop through the lab-scale column and by measuring the physical properties of samples of the resin. The test loop with the lab-scale column is currently being fabricated, and operation will start by late May. Testing will be completed by the

  9. Oxygen uptake during high-intensity running: response following a single bout of interval training.

    PubMed

    James, D V; Doust, J H

    1999-02-01

    Elevated oxygen uptake (VO2) during moderate-intensity running following a bout of interval running training has been studied previously. To further investigate this phenomenon, the VO2 response to high-intensity exercise was examined following a bout of interval running. Well-trained endurance runners were split into an experimental group [maximum oxygen uptake, VO2max 4.73 (0.39)l x min(-1)] and a reliability group [VO2max 4.77 (0.26)l x min(-1)]. The experimental group completed a training session (4 x 800 m at 1 km x h(-1) below speed at VO2max, with 3 min rest between each 800-m interval). Five minutes prior to, and 1 h following the training session, subjects completed 6 min 30 s of constant speed, high-intensity running designed to elicit 40% delta (where delta is the difference between VO2 at ventilatory threshold and VO2max; tests 1 and 2, respectively). The slow component of VO2 kinetics was quantified as the difference between the VO2 at 6 min and the VO2 at 3 min of exercise, i.e. deltaVO2(6-3). The deltaVO2(-3) was the same in two identical conditions in the reliability group [mean (SD): 0.30 (0.10)l x min(-1) vs 0.32 (0.13)l x min(-1)]. In the experimental group, the magnitude of the slow component of VO2 kinetics was increased in test 2 compared with test 1 by 24.9% [0.27 (0.14)l x min(-1) vs 0.34 (0.08)l x min(-1), P < 0.05]. The increase in deltaVO2(6-3) in the experimental group was observed in the absence of any significant change in body mass, core temperature or blood lactate concentration, either at the start or end of tests 1 or 2. It is concluded that similar mechanisms may be responsible for the slow component of VO2 kinetics and for the fatigue following the training session. It has been suggested previously that this mechanism may be linked primarily to changes within the active limb, with the recruitment of alternative and/or additional less efficient fibres. PMID:10048628

  10. Influence of pacing strategy on oxygen uptake during treadmill middle-distance running.

    PubMed

    Sandals, L E; Wood, D M; Draper, S B; James, D V B

    2006-01-01

    The oxygen uptake (VO2) attained during a constant speed 800-m pace trial on a treadmill is less than the maximal VO2 (VO2max) in male middle-distance runners with a high VO2max (i.e., > 65 ml x kg (-1) x min (-1)). We therefore investigated whether the VO2 attained was influenced by the pacing strategy adopted. Eight male middle-distance runners (age 25.8 +/- 3.3 years; height 1.78 +/- 0.10 m; mass 67.8 +/- 4.7 kg) with a personal best 800-m time of 112.0 +/- 3.3 s volunteered to participate. Subjects undertook a speed ramped progressive test to determine VO2max and three 800-m pace runs to exhaustion all in a randomised order. The three 800-m pace runs included constant speed, acceleration, and race simulation runs. Oxygen uptake was determined throughout each test using 15-s Douglas bag collections. Following the application of a 30-s rolling average, the highest VO2 during the progressive test (i.e., VO2max) and the highest VO2 during the 800-m pace runs (i.e., VO2peak) were compared. For the eight runners, VO2max was 67.2 +/- 4.3 ml x kg (-1) x min (-1) x VO2peak was 60.1 +/- 5.1 ml x kg (-1) x min (-1), 61.1 +/- 5.2 ml x kg (-1) x min (-1), and 62.2 +/- 4.9 ml x kg (-1) x min (-1), yielding values of 89.3 +/- 2.4 %, 90.8 +/- 2.8 %, and 92.5 +/- 3.1 % VO2max for the constant speed, acceleration and race simulation runs, respectively. Across runs, repeated measures ANOVA revealed a significant effect (p = 0.048). Trend analysis identified a significant linear trend (p = 0.025) with the % VO2max attained being higher for the acceleration run than the constant speed run, and higher still for the race simulation run. These results demonstrate that in middle-distance runners a) pacing strategy influences the VO2 attained, with a race simulation run elevating the VO2 attained compared with other pacing strategies, and b) regardless of pacing strategy the VO2 attained in an 800-m pace run on a treadmill is less than VO2max. PMID:16388440

  11. Machine learning and statistical methods for the prediction of maximal oxygen uptake: recent advances.

    PubMed

    Abut, Fatih; Akay, Mehmet Fatih

    2015-01-01

    Maximal oxygen uptake (VO2max) indicates how many milliliters of oxygen the body can consume in a state of intense exercise per minute. VO2max plays an important role in both sport and medical sciences for different purposes, such as indicating the endurance capacity of athletes or serving as a metric in estimating the disease risk of a person. In general, the direct measurement of VO2max provides the most accurate assessment of aerobic power. However, despite a high level of accuracy, practical limitations associated with the direct measurement of VO2max, such as the requirement of expensive and sophisticated laboratory equipment or trained staff, have led to the development of various regression models for predicting VO2max. Consequently, a lot of studies have been conducted in the last years to predict VO2max of various target audiences, ranging from soccer athletes, nonexpert swimmers, cross-country skiers to healthy-fit adults, teenagers, and children. Numerous prediction models have been developed using different sets of predictor variables and a variety of machine learning and statistical methods, including support vector machine, multilayer perceptron, general regression neural network, and multiple linear regression. The purpose of this study is to give a detailed overview about the data-driven modeling studies for the prediction of VO2max conducted in recent years and to compare the performance of various VO2max prediction models reported in related literature in terms of two well-known metrics, namely, multiple correlation coefficient (R) and standard error of estimate. The survey results reveal that with respect to regression methods used to develop prediction models, support vector machine, in general, shows better performance than other methods, whereas multiple linear regression exhibits the worst performance. PMID:26346869

  12. The effects of corticosterone and cortisone on the uptake of polyvinyl pyrrolidone and the transmission of immunoglobulin G by the small intestine in young rats.

    PubMed Central

    Morris, B; Morris, R

    1976-01-01

    1. The distribution of polyvinyl pyrrolidone along the intestinal lumen and in the intestinal wall, following oral administration to normal and corticosterone treated rats, was found to be extremely variable. Valid comparisons between the two groups of animals could not be made using this technique. 2. Three, 4 and 5 days after corticosterone treatment there was no significant change in the uptake of 125I-labelled polyvinyl pyrrolidone from standard doses injected into ligated segments of the distal small intestine; nor did the treatment induce precocious replacement of the absorptive cells in this region. Cortisone induced precocious cell replacement, a process which took up to 4 days to complete, and also led to a marked reduction in the uptake of 125I-labelled polyvinyl pyrrolidone from ligated segments of the distal intestine. 3. Three days after treatment with corticosterone (5 mg I.P. at 12 days) there was a marked reduction of labelled immunoglobulin G transport into the blood. Four and 5 days after treatment there was some recovery of the immunoglobulin G transport function. Three days after treatment with cortisone (5 mg I.P. at 12 days) there was closure of the gut to labelled immunoglobulin G. 4. The relevance of these results to antibody transmission and the termination of immunoglobulin transport is discussed. PMID:1249782

  13. Oxygen uptake and energy expenditure for children during rock climbing activity.

    PubMed

    Watts, Phillip Baxter; Ostrowski, Megan L

    2014-02-01

    The purpose of this study was to measure oxygen uptake and energy expenditure in children during rock climbing activity. 29 children (age = 10.9 ± 1.7 yr) participated in the study. A commercially available rock climbing structure with ample features for submaximal effort climbing provided continuous terrain. Participants were instructed to climb at a comfortable pace. Following an initial 5-min rest, each child climbed one sustained 5-min bout followed by 5-min sitting recovery for a total of 10 min (SUS). This was immediately followed by five 1-min climbing + 1-min recovery intervals for a second total of 10 min (INT). Expired air was analyzed continuously. Energy expenditure (EE) was determined via the Weir method for 10-s intervals throughout the full protocol. The total energy expenditure in kilocalories during the 10-min SUS period was 34.3 ± 11.3 kcal. Energy expenditure during the 10-min INT period averaged 39.3 ± 13.1 kcal and was significantly higher than during SUS (p < .05). The mean total EE for SUS + INT was 73.7 ± 24.2 kcal. EE was correlated with body mass; r = .86. The rock climbing tasks employed in this study produced EE levels similar to what have been reported in children for stair climbing, sports/games activities, and easy jogging. PMID:24018310

  14. Influence of blood donation on oxygen uptake kinetics during moderate and heavy intensity cycle exercise.

    PubMed

    Gordon, D; Marshall, K; Connell, A; Barnes, R J

    2010-05-01

    The purpose of this study was to determine the effects of a reduced whole body blood volume on the kinetic response of VO(2) during moderate and heavy intensity exercise. Six males and four females (age, 21+/-2 yrs; height, 175.2+/-5.1 cm; weight, 66.4+/-2.8 kg; VO(2)max, 53.0+/-4.1 ml x kg (-1) x min(-1)), completed a square-wave cycling ramp test to determine ventilatory threshold (VT) and VO(2max). Kinetics trials were completed 24 h pre and post donation of 450 cm (3) of blood. The kinetics trials were moderate intensity (80%VT) and heavy intensity (Delta50% VT - VO(2max)). Breath-by-breath gas exchange, heart rate, blood pressure, haemoglobin O(2) saturation, and blood [lactate] were measured throughout the trials. Post-donation haemoglobin, haematocrit and erythrocyte count were all significantly reduced (por= 0.05), or in the amplitude of the slow component. The capacity of the cardiovascular system to meet the metabolic demands of skeletal muscle at the onset of exercise does not limit the oxygen uptake. PMID:20180178

  15. Oxygen uptake during moderate intensity running: response following a single bout of interval training.

    PubMed

    James, D V; Doust, J H

    1998-05-01

    Eight male endurance runners [mean+/-(SD): age 25 (6) years; height 1.79 (0.06) m; body mass 70.5 (6.0) kg; % body fat 12.5 (3.2); maximal oxygen consumption (VO2max 62.9 (1.7) ml x kg(-1) x min(-1)] performed an interval training session, preceded immediately by test 1, followed after 1 h by test 2, and after 72 h by test 3. The training session was six 800-m intervals at 1 km x h(-1) below the velocity achieved at VO2max with 3 min of recovery between each interval. Tests 1, 2 and 3 were identical, and included collection of expired gas, measurement of ventilatory frequency (fr), heart rate (Fc)r rate of perceived exertion (RPE), and blood lactate concentration ([La-]B) during the final 5 min of 15 min of running at 50% of the velocity achieved at V02max (50% v-VO2max). Oxygen uptake (VO2), ventilation (VE), and respiratory exchange ratio (R) were subsequently determined from duplicate expired gas collections. Body mass and plasma volume changes were measured preceding and immediately following the training session, and before tests 1-3. Subjects ingested water immediately following the training session, the volume of which was determined from the loss of body mass during the session. Repeated measures analysis of variance with multiple comparison (Tukey) was used to test differences between results. No significant differences in body mass or plasma volume existed between the three test stages, indicating that the differences recorded for the measured parameters could not be attributed to changes in body mass or plasma volume between tests, and that rehydration after the interval training session was successful. A significant (P < 0.05) increase was found from test 1 to test 2 [mean (SD)] for VO2 [2.128 (0.147) to 2.200 (0.140) l x min(-1)], fc [125 (17) to 132 (16) beats x min(-1)], and RPE [9 (2) to 11 (2)]. A significant (P < 0.05) decrease was found for submaximal R [0.89 (0.03) to 0.85 (0.04)]. These results suggest that alterations in VO2 during moderate

  16. Inhibition of glucose uptake and glycogenolysis by availability of oleate in well-oxygenated perfused skeletal muscle

    PubMed Central

    Rennie, Michael J.; Holloszy, John O.

    1977-01-01

    The effects of exogenous oleate on glucose uptake, lactate production and glycogen concentration in resting and contracting skeletal muscle were studied in the perfused rat hindquarter. In preliminary studies with aged erythrocytes at a haemoglobin concentration of 8g/100ml in the perfusion medium, 1.8mm-oleate had no effect on glucose uptake or lactate production. During these studies it became evident that O2 delivery was inadequate with aged erythrocytes. Perfusion with rejuvenated human erythrocytes at a haemoglobin concentration of 12g/100ml resulted in a 2-fold higher O2 uptake at rest and a 4-fold higher O2 uptake during muscle contraction than was obtained with aged erythrocytes. Rejuvenated erythrocytes were therefore used in subsequent experiments. Glucose uptake and lactate production by the well-oxygenated hindquarter were inhibited by one-third, both at rest and during muscle contraction, when 1.8mm-oleate was added to the perfusion medium. Addition of oleate also significantly protected against glycogen depletion in the fast-twitch red and slow-twitch red types of muscle, but not in white muscle, during sciatic-nerve stimulation. In the absence of added oleate, glucose was confined to the extracellular space in resting muscle. Addition of oleate resulted in intracellular glucose accumulation in red muscle. Contractile activity resulted in accumulation of intracellular glucose in all three muscle types, and this effect was significantly augmented in the red types of muscle by perfusion with oleate. The concentrations of citrate and glucose 6-phosphate were also increased in red muscle perfused with oleate. We conclude that, as in the heart, availability of fatty acids has an inhibitory effect on glucose uptake and glycogen utilization in well-oxygenated red skeletal muscle. PMID:597267

  17. Prediction of oxygen uptake during walking in ambulatory persons with multiple sclerosis.

    PubMed

    Agiovlasitis, Stamatis; Sandroff, Brian M; Motl, Robert W

    2016-01-01

    People with multiple sclerosis (MS) have an increased rate of gross oxygen uptake (gross-VO2) during treadmill walking, and their gross-VO2 may further vary with walking impairment. This study attempted to develop an equation for predicting gross-VO2 from walking speed and an index of walking impairment in persons with MS and examine its accuracy. Gross-VO2 was measured with open-circuit spirometry in 43 persons with MS (47 +/- 9 yr; 38 women) during five treadmill walking trials, each lasting 6 min, at 2.0, 2.5, 3.0, 3.5, and 4.0 mph (0.89, 1.12, 1.34, 1.56, and 1.79 m/s). The 12-Item Multiple Sclerosis Walking Scale (MSWS-12) and the single-item Patient Determined Disease Steps scale (PDDS) provided indices of walking impairment. Multilevel modeling with random intercepts and slopes showed significant effects of speed and MSWS-12 on gross-VO2 (p

  18. Short-chain oxygenated VOCs: Emission and uptake by plants and atmospheric sources, sinks, and concentrations

    NASA Astrophysics Data System (ADS)

    Seco, Roger; Peñuelas, Josep; Filella, Iolanda

    Emissions of volatile organic compounds (VOCs) have multiple atmospheric implications and play many roles in plant physiology and ecology. Among these VOCs, growing interest is being devoted to a group of short-chain oxygenated VOCs (oxVOCs). Technology improvements such as proton transfer reaction-mass spectrometry are facilitating the study of these hydrocarbons and new data regarding these compounds is continuously appearing. Here we review current knowledge of the emissions of these oxVOCs by plants and the factors that control them, and also provide an overview of sources, sinks, and concentrations found in the atmosphere. The oxVOCs reviewed here are formic and acetic acids, acetone, formaldehyde, acetaldehyde, methanol, and ethanol. In general, because of their water solubility (low gas-liquid partitioning coefficient), the plant-atmosphere exchange is stomatal-dependent, although it can also take place via the cuticle. This exchange is also determined by atmospheric mixing ratios. These compounds have relatively long atmospheric half-lives and reach considerable concentrations in the atmosphere in the range of ppbv. Likewise, under non-stressed conditions plants can emit all of these oxVOCs together at fluxes ranging from 0.2 up to 4.8 μg(C)g -1(leaf dry weight)h -1 and at rates that increase several-fold when under stress. Gaps in our knowledge regarding the processes involved in the synthesis, emission, uptake, and atmospheric reactivity of oxVOCs precludes the clarification of exactly what is conditioning plant-atmosphere exchange—and also when, how, and why this occurs—and these lacunae therefore warrant further research in this field.

  19. Peak Oxygen Uptake after Cardiac Rehabilitation: A Randomized Controlled Trial of a 12-Month Maintenance Program versus Usual Care

    PubMed Central

    Madssen, Erik; Arbo, Ingerid; Granøien, Ingrid; Walderhaug, Liv; Moholdt, Trine

    2014-01-01

    Background Exercise capacity is a strong predictor of survival in patients with coronary artery disease (CAD). Exercise capacity improves after cardiac rehabilitation exercise training, but previous studies have demonstrated a decline in peak oxygen uptake after ending a formal rehabilitation program. There is a lack of knowledge on how long-term exercise adherence can be achieved in CAD patients. We therefore assessed if a 12-month maintenance program following cardiac rehabilitation would lead to increased adherence to exercise and increased exercise capacity compared to usual care. Materials and Methods Two-centre, open, parallel randomized controlled trial with 12 months follow-up comparing usual care to a maintenance program. The maintenance program consisted of one monthly supervised high intensity interval training session, a written exercise program and exercise diary, and a maximum exercise test every third month during follow-up. Forty-nine patients (15 women) on optimal medical treatment were included following discharge from cardiac rehabilitation. The primary endpoint was change in peak oxygen uptake at follow-up; secondary endpoints were physical activity level, quality of life and blood markers of cardiovascular risk. Results There was no change in peak oxygen uptake from baseline to follow-up in either group (intervention group 27.9 (±4.7) to 28.8 (±5.6) mL·kg (-1) min (−1), control group 32.0 (±6.2) to 32.8 (±5.8) mL·kg (−1) min (−1), with no between-group difference, p = 0.22). Quality of life and blood biomarkers remained essentially unchanged, and both self-reported and measured physical activity levels were similar between groups after 12 months. Conclusions A maintenance exercise program for 12 months did not improve adherence to exercise or peak oxygen uptake in CAD patients after discharge from cardiac rehabilitation compared to usual care. This suggests that infrequent supervised high intensity interval training sessions are

  20. Evaluation of Optimum Moisture Content for Composting of Beef Manure and Bedding Material Mixtures Using Oxygen Uptake Measurement

    PubMed Central

    Kim, Eunjong; Lee, Dong-Hyun; Won, Seunggun; Ahn, Heekwon

    2016-01-01

    Moisture content influences physiological characteristics of microbes and physical structure of solid matrices during composting of animal manure. If moisture content is maintained at a proper level, aerobic microorganisms show more active oxygen consumption during composting due to increased microbial activity. In this study, optimum moisture levels for composting of two bedding materials (sawdust, rice hull) and two different mixtures of bedding and beef manure (BS, Beef cattle manure+sawdust; BR, Beef cattle manure+rice hull) were determined based on oxygen uptake rate measured by a pressure sensor method. A broad range of oxygen uptake rates (0.3 to 33.3 mg O2/g VS d) were monitored as a function of moisture level and composting feedstock type. The maximum oxygen consumption of each material was observed near the saturated condition, which ranged from 75% to 98% of water holding capacity. The optimum moisture content of BS and BR were 70% and 57% on a wet basis, respectively. Although BS’s optimum moisture content was near saturated state, its free air space kept a favorable level (above 30%) for aerobic composting due to the sawdust’s coarse particle size and bulking effect. PMID:26954138

  1. Evaluation of Optimum Moisture Content for Composting of Beef Manure and Bedding Material Mixtures Using Oxygen Uptake Measurement.

    PubMed

    Kim, Eunjong; Lee, Dong-Hyun; Won, Seunggun; Ahn, Heekwon

    2016-05-01

    Moisture content influences physiological characteristics of microbes and physical structure of solid matrices during composting of animal manure. If moisture content is maintained at a proper level, aerobic microorganisms show more active oxygen consumption during composting due to increased microbial activity. In this study, optimum moisture levels for composting of two bedding materials (sawdust, rice hull) and two different mixtures of bedding and beef manure (BS, Beef cattle manure+sawdust; BR, Beef cattle manure+rice hull) were determined based on oxygen uptake rate measured by a pressure sensor method. A broad range of oxygen uptake rates (0.3 to 33.3 mg O2/g VS d) were monitored as a function of moisture level and composting feedstock type. The maximum oxygen consumption of each material was observed near the saturated condition, which ranged from 75% to 98% of water holding capacity. The optimum moisture content of BS and BR were 70% and 57% on a wet basis, respectively. Although BS's optimum moisture content was near saturated state, its free air space kept a favorable level (above 30%) for aerobic composting due to the sawdust's coarse particle size and bulking effect. PMID:26954138

  2. Species-Dependent Uptake of Glycylsarcosine but Not Oseltamivir in Pichia pastoris Expressing the Rat, Mouse, and Human Intestinal Peptide Transporter PEPT1

    PubMed Central

    Hu, Yongjun; Chen, Xiaomei

    2012-01-01

    The purpose of this study was to determine whether glycylsarcosine (a model dipeptide) and oseltamivir (an antiviral prodrug) exhibited a species-dependent uptake in yeast Pichia pastoris expressing the rat, mouse, and human homologs of PEPT1. Experiments were performed with [3H]glycylsarcosine (GlySar) in yeast P. pastoris expressing human, mouse, and rat peptide transporter 1 (PEPT1), in which uptake was examined as a function of time, concentration, potential inhibitors, and the dose-response inhibition of GlySar by oseltamivir. Studies with [14C]oseltamivir were also performed under identical experimental conditions. We found that GlySar exhibited saturable uptake in all three species, with Km values for human (0.86 mM) > mouse (0.30 mM) > rat (0.16 mM). GlySar uptake in the yeast transformants was specific for peptides (glycylproline) and peptide-like drugs (cefadroxil, cephradine, and valacyclovir), but was unaffected by glycine, l-histidine, cefazolin, cephalothin, cephapirin, acyclovir, 4-acetamido-4′-isothiocyanostilbene-2,2′-disulfonic acid, tetraethylammonium, and elacridar. Although oseltamivir caused a dose-dependent inhibition of GlySar uptake [IC50 values for human (27.4 mM) > rat (18.3 mM) > mouse (10.7 mM)], the clinical relevance of this interaction would be very low in humans. Of importance, oseltamivir was not a substrate for the intestinal PEPT1 transporter in yeast expressing the three mammalian species tested. Instead, the prodrug exhibited nonspecific binding to the yeast vector and PEPT1 transformants. Finally, the mouse appeared to be a better animal model than the rat for exploring the intestinal absorption and pharmacokinetics of peptides and peptide-like drugs in human. PMID:22490229

  3. Mechanisms of dietary Cu uptake in freshwater rainbow trout: evidence for Na-assisted Cu transport and a specific metal carrier in the intestine.

    PubMed

    Nadella, Sunita Rao; Grosell, Martin; Wood, Chris M

    2007-05-01

    Copper (Cu) is both a vital nutrient and a potent toxicant. The objective of this study was to analyze the mechanistic nature of intestinal Cu transport in rainbow trout using radiolabeled Cu (64Cu) and an in vitro gut sac technique. Reduction of mucosal NaCl levels inhibited Cu transport while increase caused stimulation; Na(2)SO(4) had an identical effect, implicating Na(+) rather than the anion. These responses were unrelated to solvent drag, osmotic pressure or changes in transepithelial potential. The presence of elevated luminal Ag stimulated Cu and Na(+) uptake. Phenamil caused a partial inhibition of both Cu and Na(+) uptake while hypercapnia stimulated Na(+) and Cu transport. Cu uptake was sensitive to luminal pH and inhibited by a tenfold excess of Fe and Zn. These factors had no effect on Na(+ )uptake. On the basis of these results we propose a novel Na(+)-assisted mechanism of Cu uptake wherein the Na(+) gradient stimulates an increase in the H(+) concentration of the brushborder creating a suitable microenvironment for the effective transport of Cu via either DMT1 or Ctr1. PMID:17279389

  4. Effects of aerobic fitness on oxygen uptake kinetics in heavy intensity swimming.

    PubMed

    Reis, Joana F; Alves, Francisco B; Bruno, Paula M; Vleck, Veronica; Millet, Gregoire P

    2012-05-01

    This study aimed to characterise both the VO2 kinetics within constant heavy-intensity swimming exercise, and to assess the relationships between VO2 kinetics and other parameters of aerobic fitness, in well-trained swimmers. On separate days, 21 male swimmers completed: (1) an incremental swimming test to determine their maximal oxygen uptake (VO2 max), first ventilatory threshold (VT), and the velocity associated with VO2max (vVO(2 max)) and (2) two square-wave transitions from rest to heavy-intensity exercise, to determine their VO2 kinetics. All the tests involved breath-by-breath analysis of freestyle swimming using a swimming snorkel. VO2 kinetics was modelled with two exponential functions. The mean values for the incremental test were 56.0 ± 6.0 ml min(-1) kg(-1), 1.45 ± 0.08 m s(-1); and 42.1 ± 5.7 ml min(-1) kg(-1) for VO2 max, vVO(2 max) and VT, respectively. For the square-wave transition, the time constant of the primary phase (sp) averaged 17.3 ± 5.4 s and the relevant slow component (A'sc) averaged 4.8 ± 2.9 ml min(-1) kg(-1) [representing 8.9% of the end-exercise VO2 (%A'sc)]. sp was correlated with vVO(2 max) (r = -0.55, P = 0.01), but not with either VO2max (r = 0.05, ns) or VT (r = 0.14, ns). The %A' sc did not correlate with either VO2max (r = -0.14, ns) or vVO(2 max) (r = 0.06, ns), but was inversely related with VT (r = -0.61, P < 0.01). This study was the first to describe the VO2 kinetics in heavy-intensity swimming using specific swimming exercise and appropriate methods. As has been demonstrated in cycling, faster VO2 kinetics allow higher aerobic power outputs to be attained. The slow component seems to be reduced in swimmers with higher ventilatory thresholds. PMID:21879352

  5. Maximum Oxygen Uptake During Long-Duration Space Flight: Preliminary Results

    NASA Technical Reports Server (NTRS)

    Moore, A. D., Jr.; Evetts, S. N.; Feiveson, A.H.; Lee, S. M. C.; McCleary, F. A.; Platts, S. H.; Ploutz-Snyder, L.

    2010-01-01

    INTRODUCTION: Maximum oxygen uptake (VO2max) is maintained during space flight lasting <15 d, but has not been measured during long-duration missions. This abstract describes pre-flight and in-flight preliminary findings from the International Space Station (ISS) VO2max experiment. METHODS: Seven astronauts (4 M, 3 F: 47 +/- 5 yr, 174 +/- 7 cm, 74.1 +/- 14.7 kg [mean +/- SD]) performed cycle exercise tests to volitional maximum approx.45 d before flight and tests were scheduled every 30 d during flight beginning on flight day (FD) 14. Tests consisted of three 5-min stages designed to elicit 25%, 50%, and 75% of preflight VO2max, followed by 25 W/min increases. VO2 and heart rate (HR) were measured using the ISS Portable Pulmonary Function System (PPFS) (Damec, Odense, DK). Unfortunately the PPFS did not arrive at the ISS in time to support early test sessions for 3 crewmembers. Descriptive statistics are presented for pre-flight vs. late-flight (FD 147 +/- 33 d) comparisons for all subjects (n=7); and pre-flight, early (FD 18 +/- 3) and late-flight (FD 156 +/- 5) data are presented for subjects (n=4) who completed all of these test sessions. RESULTS: When all subjects are considered, average VO2max decreased from pre- to late in-flight (2.98 +/- 0.85 vs. 2.57 +/- 0.50 L/min) while maximum HR late-flight seemed unchanged (178 +/- 9 vs. 175 +/- 8 beats/min). Similarly, for subjects who completed pre-, early, and late flight measurements (n=4), mean VO2max declined from 3.19 +/- 0.75 L/min preflight to 2.43 +/- 0.43 and 2.62 +/- 0.38 L/min early and late-flight, respectively. Maximum HR was 183 +/- 8, 174 +/- 8, and 179 +/- 6 beats/min pre-, early- and late-flight. DISCUSSION: Average VO2max declined during flight and did not appreciably recover as flight duration increased; however much inter-subject variation occurred in these changes.

  6. Estimation of maximal oxygen uptake via submaximal exercise testing in sports, clinical, and home settings.

    PubMed

    Sartor, Francesco; Vernillo, Gianluca; de Morree, Helma M; Bonomi, Alberto G; La Torre, Antonio; Kubis, Hans-Peter; Veicsteinas, Arsenio

    2013-09-01

    Assessment of the functional capacity of the cardiovascular system is essential in sports medicine. For athletes, the maximal oxygen uptake [Formula: see text] provides valuable information about their aerobic power. In the clinical setting, the (VO(2max)) provides important diagnostic and prognostic information in several clinical populations, such as patients with coronary artery disease or heart failure. Likewise, VO(2max) assessment can be very important to evaluate fitness in asymptomatic adults. Although direct determination of [VO(2max) is the most accurate method, it requires a maximal level of exertion, which brings a higher risk of adverse events in individuals with an intermediate to high risk of cardiovascular problems. Estimation of VO(2max) during submaximal exercise testing can offer a precious alternative. Over the past decades, many protocols have been developed for this purpose. The present review gives an overview of these submaximal protocols and aims to facilitate appropriate test selection in sports, clinical, and home settings. Several factors must be considered when selecting a protocol: (i) The population being tested and its specific needs in terms of safety, supervision, and accuracy and repeatability of the VO(2max) estimation. (ii) The parameters upon which the prediction is based (e.g. heart rate, power output, rating of perceived exertion [RPE]), as well as the need for additional clinically relevant parameters (e.g. blood pressure, ECG). (iii) The appropriate test modality that should meet the above-mentioned requirements should also be in line with the functional mobility of the target population, and depends on the available equipment. In the sports setting, high repeatability is crucial to track training-induced seasonal changes. In the clinical setting, special attention must be paid to the test modality, because multiple physiological parameters often need to be measured during test execution. When estimating VO(2max), one has

  7. Evaluation of Maximal Oxygen Uptake and Submaximal Estimates of VO2max Before, During, and After Long Duration International Space Station Missions

    NASA Technical Reports Server (NTRS)

    2008-01-01

    Evaluation of Maximal Oxygen Uptake and Submaximal Estimates of VO2max Before, During, and After Long Duration International Space Station Missions (VO2max) will document changes in maximum oxygen uptake for crewmembers onboard the International Space Station (ISS) on long-duration missions, greater than 90 days. This investigation will establish the characteristics of VO2max during flight and assess the validity of the current methods of tracking aerobic capacity change during and following the ISS missions.

  8. The role of oxygen in the uptake of deuterium in lithiated graphite

    SciTech Connect

    Taylor, C. N.; Luitjohan, K. E.; Dadras, J.; Allain, J. P.; Krstic, P. S.; Skinner, C. H.

    2013-12-14

    We investigate the mechanism of deuterium retention by lithiated graphite and its relationship to the oxygen concentration through surface sensitive experiments and atomistic simulations. Deposition of lithium on graphite yielded 5%–8% oxygen surface concentration and when subsequently irradiated with D ions at energies between 500 and 1000 eV/amu and fluences over 10{sup 16} cm{sup −2} the oxygen concentration rose to between 25% and 40%. These enhanced oxygen levels were reached in a few seconds compared to about 300 h when the lithiated graphite was allowed to adsorb oxygen from the ambient environment under equilibrium conditions. Irradiating graphite without lithium deposition, however, resulted in complete removal of oxygen to levels below the detection limit of XPS (e.g., <1%). These findings confirm the predictions of atomistic simulations, which had concluded that oxygen was the primary component for the enhanced hydrogen retention chemistry on the lithiated graphite surface.

  9. The role of oxygen in the uptake of deuterium in lithiated graphite

    SciTech Connect

    C.N. Taylor; J. Dadras; K.E. Luitjohan; J.P. Allain; P.S. Krstic; C.H. Skinner

    2013-12-01

    We investigate the mechanism of deuterium retention by lithiated graphite and its relationship to the oxygen concentration through surface sensitive experiments and atomistic simulations. Deposition of lithium on graphite yielded 5%–8% oxygen surface concentration and when subsequently irradiated with D ions at energies between 500 and 1000?eV/amu and fluences over 1016?cm-2 the oxygen concentration rose to between 25% and 40%. These enhanced oxygen levels were reached in a few seconds compared to about 300?h when the lithiated graphite was allowed to adsorb oxygen from the ambient environment under equilibrium conditions. Irradiating graphite without lithium deposition, however, resulted in complete removal of oxygen to levels below the detection limit of XPS (e.g., <1%). These findings confirm the predictions of atomistic simulations, which had concluded that oxygen was the primary component for the enhanced hydrogen retention chemistry on the lithiated graphite surface.

  10. Skeletal muscle blood flow and oxygen uptake at rest and during exercise in humans: a pet study with nitric oxide and cyclooxygenase inhibition.

    PubMed

    Heinonen, Ilkka; Ilkka, Heinonen; Saltin, Bengt; Bengt, Saltin; Kemppainen, Jukka; Jukka, Kemppainen; Sipilä, Hannu T; Oikonen, Vesa; Vesa, Oikonen; Nuutila, Pirjo; Pirjo, Nuutila; Knuuti, Juhani; Juhani, Knuuti; Kalliokoski, Kari; Kari, Kalliokoski; Hellsten, Ylva; Ylva, Hellsten

    2011-04-01

    The aim of the present study was to determine the effect of nitric oxide and prostanoids on microcirculation and oxygen uptake, specifically in the active skeletal muscle by use of positron emission tomography (PET). Healthy males performed three 5-min bouts of light knee-extensor exercise. Skeletal muscle blood flow and oxygen uptake were measured at rest and during the exercise using PET with H(2)O(15) and (15)O(2) during: 1) control conditions; 2) nitric oxide synthase (NOS) inhibition by arterial infusion of N(G)-monomethyl-L-arginine (L-NMMA), and 3) combined NOS and cyclooxygenase (COX) inhibition by arterial infusion of L-NMMA and indomethacin. At rest, inhibition of NOS alone and in combination with indomethacin reduced (P < 0.05) muscle blood flow. NOS inhibition increased (P < 0.05) limb oxygen extraction fraction (OEF) more than the reduction in muscle blood flow, resulting in an ∼20% increase (P < 0.05) in resting muscle oxygen consumption. During exercise, muscle blood flow and oxygen uptake were not altered with NOS inhibition, whereas muscle OEF was increased (P < 0.05). NOS and COX inhibition reduced (P < 0.05) blood flow in working quadriceps femoris muscle by 13%, whereas muscle OEF and oxygen uptake were enhanced by 51 and 30%, respectively. In conclusion, by specifically measuring blood flow and oxygen uptake by the use of PET instead of whole limb measurements, the present study shows for the first time in humans that inhibition of NO formation enhances resting muscle oxygen uptake and that combined inhibition of NOS and COX during exercise increases muscle oxygen uptake. PMID:21257921

  11. Laser irradiation of mouse spermatozoa enhances in-vitro fertilization and Ca2+ uptake via reactive oxygen species

    NASA Astrophysics Data System (ADS)

    Cohen, Natalie; Lubart, Rachel; Rubinstein, Sara; Breitbart, Haim

    1996-11-01

    630 nm He-Ne laser irradiation was found to have a profound influence on Ca2+ uptake in mouse spermatozoa and the fertilizing potential of these cells. Laser irradiation affected mainly the mitochondrial Ca2+ transport mechanisms. Furthermore, the effect of light was found to be Ca2+-dependent. We demonstrate that reactive oxygen species (ROS) are involved in the cascade of biochemical events evoked by laser irradiation. A causal association between laser irradiation, ROS generation, and sperm function was indicated by studies with ROS scavengers, superoxide dismutase (SOD) and catalase, and exogenous hydrogen peroxide. SOD treatment resulted in increased Ca2+ uptake and in enhanced fertilization rate. Catalase treatment impaired the light-induced stimulation in Ca2+ uptake and fertilization rate. Exogenous hydrogen peroxide was found to enhance Ca2+ uptake in mouse spermatozoa and the fertilizing capability of these cells in a dose-dependent manner. These results suggest that the effect of 630 nm He-Ne laser irradiation is mediated through the generation of hydrogen peroxide by the spermatozoa and that this effect plays a significant role in the augmentation of the sperm cells' capability to fertilize metaphase II-arrested eggs in-vitro.

  12. Simultaneous phosphorus uptake and denitrification by EBPR-r biofilm under aerobic conditions: effect of dissolved oxygen.

    PubMed

    Wong, Pan Yu; Ginige, Maneesha P; Kaksonen, Anna H; Cord-Ruwisch, Ralf; Sutton, David C; Cheng, Ka Yu

    2015-01-01

    A biofilm process, termed enhanced biological phosphorus removal and recovery (EBPR-r), was recently developed as a post-denitrification approach to facilitate phosphorus (P) recovery from wastewater. Although simultaneous P uptake and denitrification was achieved despite substantial intrusion of dissolved oxygen (DO >6 mg/L), to what extent DO affects the process was unclear. Hence, in this study a series of batch experiments was conducted to assess the activity of the biofilm under various DO concentrations. The biofilm was first allowed to store acetate (as internal storage) under anaerobic conditions, and was then subjected to various conditions for P uptake (DO: 0-8 mg/L; nitrate: 10 mg-N/L; phosphate: 8 mg-P/L). The results suggest that even at a saturating DO concentration (8 mg/L), the biofilm could take up P and denitrify efficiently (0.70 mmol e(-)/g total solids*h). However, such aerobic denitrification activity was reduced when the biofilm structure was physically disturbed, suggesting that this phenomenon was a consequence of the presence of oxygen gradient across the biofilm. We conclude that when a biofilm system is used, EBPR-r can be effectively operated as a post-denitrification process, even when oxygen intrusion occurs. PMID:26398030

  13. Evidence for carrier-mediated uptake and efflux of sugars at the serosal side of the rat intestinal mucosa in vitro.

    PubMed Central

    Bronk, J R; Ingham, P A

    1976-01-01

    A modification of the everted sac technique is described which allows several sacs to be prepared rapidly and simultaneously from the same segment of rat intestine. 2. A method has been developed for comparing the transport of two sugars by measuring changes in the ratios of their concentrations as they pass across the intestinal wall. 3. With this method significant differences were observed between the D-[3H]galactose and L-[14C]glucose ratios in the mucosal epithelium, the serosal tissue and the serosal compartment. These results indicate that both the efflux of galactose from the serosal side of the mucosal epithelium and the uptake of the sugar into the mucosa are carrier-mediated processes. 4. The mediated efflux of galactose at the serosal side of the epithelial layer is inhibited by the presence of phlorizin on the mucosal side and to some extent by any reduction in the mucosal Na+ concentration. Both of these treatments inhibited galactose uptake at the brush border. Serosal efflux of the sugar appeared to be saturated at high concentrations of D-galactose. 5. Pre-treatment of the sacs with mercuric chloride considerably reduced D-galactose uptake from the luminal side, but did not affect its efflux relative to L-glucose at the serosal side of the mucosal epithelium. 6. Carrier-mediated sugar uptake into the mucosal epithelium from the serosal side was also examined. The role of the bidirectional, carrier-mediated sugar transport processes at the serosal pole of the mucosal epithelial cell in transintestinal transport is discussed. PMID:1255529

  14. L-arginine stimulates CAT-1-mediated arginine uptake and regulation of inducible nitric oxide synthase for the growth of chick intestinal epithelial cells.

    PubMed

    Yuan, Chao; Zhang, Xiaoyun; He, Qiang; Li, Junming; Lu, Jianjun; Zou, Xiaoting

    2015-01-01

    L-arginine (L-Arg) uptake is mediated by members of cationic amino acid transporter (CAT) family and may coincide with the induction of nitric oxide synthases (NOS). The present study was conducted to investigate the extracellular concentrations of L-Arg regulating the CAT-1, CAT-4 and inducible NOS (iNOS) in chick intestinal epithelial cells. The cells were cultured for 4 days in Arg-free Dulbecco's modified Eagle's medium containing 10, 100, 200, 400, or 600 μM L-Arg. Cell viability, nitric oxide (NO) concentrations, uptake and metabolism of L-[3H]-Arg as well as expression of CAT-1, CAT-4, and iNOS were determined. Our results showed that L-Arg enhances cell growth with a maximal response at 10-400 μM. Addition of 100, 200, or 400 μM L-Arg increased the L-[3H]-Arg uptake, which was associated with greater conversion of L-[3H]-citrulline and NO production in comparison with 10 μM L-Arg group. Increasing extracellular concentrations of L-Arg from 10 to 400 μM dose dependently increased the levels of CAT-1 mRNA and protein, while no effect on CAT-4 mRNA abundance was found. Furthermore, supplementation of 100, 200, or 400 μM L-Arg upregulated the expression of iNOS mRNA, and the relative protein levels for iNOS in 200 and 400 μM L-Arg groups were higher than those in 10 and 100 μM L-Arg groups. Collectively, we conclude that the CAT-1 isoform plays a role in L-Arg uptake, and L-Arg-mediated elevation of NO via iNOS promotes the growth of chick intestinal epithelial cells. PMID:25336270

  15. Chronic reactive oxygen species exposure inhibits glucose uptake and causes insulin resistance in C2C12 myotubes.

    PubMed

    Ding, Hongwen; Heng, Baoli; He, Wenfang; Shi, Liping; Lai, Caiyong; Xiao, Long; Ren, Haolin; Mo, Shijie; Su, Zexuan

    2016-09-16

    Reactive oxygen species (ROS) is an important regulator in cellular signaling transduction, and many previous studies have indicated that acute ROS stimulation improves insulin sensitivity in skeletal muscle. In the study, we found that chronic ROS treatment caused serious insulin resistance in C2C12 myotubes. Glucose uptake and consumption assay indicated that pretreatment with 80 μM H2O2 for 2 h inhibited insulin-stimulated glucose uptake in C2C12 myotubes, and the reason for it, is that chronic H2O2 treatment decreased insulin-induced glucose transporter 4 (GLUT4) translocation from cell plasma to cell membrane. Moreover, Akt2 phosphorylation depended on insulin was reduced in C2C12 myotubes of chronic H2O2 treatment. Together, this study provides further demonstration that chronic ROS stress is associated with insulin resistance of skeletal muscle in the progression of type 2 diabetes. PMID:27501754

  16. Induction of arginase II by intestinal epithelium promotes the uptake of L-arginine from the lumen of C. parvum infected porcine ileum

    PubMed Central

    Gookin, Jody L.; Stauffer, Stephen H.; Coccaro, Maria R.

    2013-01-01

    Objectives To determine the specific transport system activities and expression of transporter genes responsible for uptake of L-arginine from the lumen of normal and C. parvum infected neonatal porcine ileum and the influence of L-arginine catabolic pathways on L-arginine uptake. Methods Intact sheets of ileal mucosa from control and C. parvum infected neonatal piglets were mounted in Ussing chambers and the uptake of 14C-L-arginine was determined under initial rate conditions and in the presence of transport system-selective inhibitors. Epithelial expression of L-arginine transporter genes was quantified by real time RT-PCR. L-arginine catabolic enzyme expression was examined by immunoblotting epithelial lysates for arginase I and II. The role of intracellular catabolism in promoting uptake of L-arginine was determined by pharmacological inhibition of NOS and arginase activities. Results C. parvum infected ileum transported L-arginine at rates equivalent to uninfected epithelium despite profound villous atrophy. This was attributed to enhanced uptake of L-arginine by individual epithelial cells in the infection. There were no differences in L-arginine transport system activities (y+ and B0,+) or level of transporter gene expression (CAT-1, CAT-2A, and ATB0,+) between uninfected and C. parvum infected epithelial cells. However, infected epithelia had induced expression of the L-arginine hydrolytic enzyme arginase II and lower concentrations of L-arginine. Further, transport of L-arginine by the infected epithelium was significantly inhibited by pharmacological blockade of arginase. Conclusions Intracellular catabolism by arginase II, the induction of which has not been previously described for intestinal epithelium, facilitates uptake of L-arginine by infected epithelium using transport systems that do not differ from that of uninfected cells. Induction of arginase II may limit NO synthesis by competing with NOS for utilization of L-arginine or promote use of L

  17. Usefulness of Decrease in Oxygen Uptake Efficiency to Identify Gas Exchange Abnormality in Patients with Idiopathic Pulmonary Arterial Hypertension

    PubMed Central

    Yang, Wenlan; Guo, Jian; Zhang, Yan; Sapkota, Rikesh; Kushwaha, Shailendra Prasad; Gong, Sugang; Sun, Xingguo; Liu, Jinming

    2014-01-01

    Background Decline in oxygen uptake efficiency (OUE), especially during exercise, is found in patients with chronic heart failure. In this study we aimed to test the validity and usefulness of OUE in evaluating gas exchange abnormality of patients with idiopathic pulmonary arterial hypertension (IPAH). Methods We retrospectively investigated the cardiopulmonary exercise test (CPET) with gas exchange measurements in 32 patients with confirmed IPAH. All patients also had resting hemodynamic measurements and pulmonary function test (PFT). Sixteen healthy subjects, matched by age, sex, and body size were used as controls, also had CPET and PFT measurements. Results In IPAH patients, the magnitude of absolute and percentage of predicted (%pred) oxygen uptake efficiency slope (OUES) and oxygen uptake efficiency plateau (OUEP), as well as several other CPET parameters, were strikingly worse than healthy subjects (P<0.0001). Pattern of changes in OUE in patients is similar to that in controls, In IPAH patients, OUE values at rest, warming up, anaerobic threshold and peak exercise were all significantly lower than in normal (P<0.0001). OUEP%pred, better than OUES%pred, correlated significantly with New York Heart Association (NYHA) functional Class (r = −0.724, P<0.005), Total Pulmonary Vascular Resistance (TPVR) (r = −0.694, P<0.005), diffusing capacity for carbon monoxide (DLCO) (r = 0.577, P<0.05), and the lowest ventilation versus CO2 output ratio during exercise (LowestV˙E/V˙CO2) (r = −0.902, P<0.0001). In addition, the coefficient of variation (COV) of OUEP was lower (20.9%) markedly than OUES (34.3%) (P<0.0001). Conclusions In patients with IPAH, OUES and OUEP are both significantly lower than the healthy subjects. OUEP is a better physiological parameter than OUES in evaluating the gas exchange abnormality of patients with IPAH. PMID:24905576

  18. Oxygen Uptake and Photosynthesis of the Red Macroalga, Chondrus crispus, in Seawater

    PubMed Central

    Brechignac, François; Andre, Marcel

    1984-01-01

    With an experimental system using mass spectrometry techniques and infra-red gas analysis of CO2 developed for aquatic plants, we studied the responses to various light intensities and CO2 concentrations of photosynthesis and O2 uptake of the red macroalga Chondrus crispus S. The CO2 exchange resistance at air-water interface which could limit the photosynthesis was experimentally measured. It allowed the calculation of the free dissolved CO2 concentration. The response to light showed a small O2 uptake (37% of net photosynthesis in standard conditions) compared to C3 plants; it was always higher than dark respiration and probably included a photoindependent part. The response to CO2 showed: (a) an O2 uptake relatively insensitive to CO2 concentration and not completely inhibited with high CO2, (b) a general inhibition of gas exchanges below 130 microliters CO2 per liter (gas phase), (c) an absence of an inverse relationship between O2 and CO2 uptakes, and (d) a low apparent Km of photosynthesis for free CO2 (1 micromolar). These results suggest that O2 uptake in the light is the sum of different oxidation processes such as the glycolate pathway, the Mehler reaction, and mitochondrial respiration. The high affinity for CO2 is discussed in relation to the use of HCO3− and/or the internal CO2 accumulation. PMID:16663760

  19. Effect of the Artificial Sweetener, Acesulfame Potassium, a Sweet Taste Receptor Agonist, on Glucose Uptake in Small Intestinal Cell Lines

    PubMed Central

    Zheng, Ye; Sarr, Michael G.

    2012-01-01

    Sweet taste receptors may enhance glucose absorption. AIM To explore the cell biology of sweet taste receptors on glucose uptake. HYPOTHESIS Artificial sweeteners increase glucose uptake via activating sweet taste receptors in the enterocyte to translocate GLUT2 to the apical membrane through the PLC βII pathway. METHODS Caco-2, RIE-1, and IEC-6 cells, starved from glucose for 1 h were pre-incubated with 10 mM acesulfame potassium (AceK). Glucose uptake was measured by incubating cells for 1 to 10 min with 0.5–50 mM glucose with or without U-73122, chelerythrine, and cytochalasin B. RESULTS In Caco-2 and RIE-1 cells, 10 mM AceK increased glucose uptake by 20~30% at glucose ≥ 25 mM, but not in lesser glucose concentrations (≤10 mM), nor at 1 min or 10 min incubations. U-73122 inhibited uptake at glucose ≥ 25 mM and for 5 min incubation; chelerythrine and cytochalasin B had similar effects. No effect occurred in IEC-6 cells. SUMMARY Activation of sweet taste receptors had no effect on glucose uptake in low (<25 mM) glucose concentrations but increased uptake at greater concentrations (≥ 25 mM). CONCLUSIONS Role of artificial sweeteners on glucose uptake appears to act in part by effects on the enterocyte itself. PMID:22948835

  20. Influence of Chironomus riparius (Diptera, Chironomidae) and Tubifex tubifex (Annelida, Oligochaeta) on oxygen uptake by sediments. Consequences of uranium contamination.

    PubMed

    Lagauzère, S; Pischedda, L; Cuny, P; Gilbert, F; Stora, G; Bonzom, J-M

    2009-04-01

    The diffusive oxygen uptake (DOU) of sediments inhabited by Chironomus riparius and Tubifex tubifex was investigated using a planar oxygen optode device, and complemented by measurements of bioturbation activity. Additional experiments were performed within contaminated sediments to assess the impact of uranium on these processes. After 72h, the two invertebrate species significantly increased the DOU of sediments (13-14%), and no temporal variation occurred afterwards. Within contaminated sediments, it was already 24% higher before the introduction of the organisms, suggesting that uranium modified the sediment biogeochemistry. Although the two species firstly reacted by avoidance of contaminated sediment, they finally colonized it. Their bioturbation activity was reduced but, for T. tubifex, it remained sufficient to induce a release of uranium to the water column and an increase of the DOU (53%). These results highlight the necessity of further investigations to take into account the interactions between bioturbation, microbial metabolism and pollutants. PMID:19121883

  1. Calculation of hydrogen and oxygen uptake in fuel rod cladding during severe accidents using the integral diffusion method -- Preliminary design report

    SciTech Connect

    Siefken, L.J.

    1999-02-01

    Preliminary designs are described for models of hydrogen and oxygen uptake in fuel rod cladding during severe accidents. Calculation of the uptake involves the modeling of seven processes: (1) diffusion of oxygen from the bulk gas into the boundary layer at the external cladding surface, (2) diffusion from the boundary layer into the oxide layer, (3) diffusion from the inner surface of the oxide layer into the metallic part of the cladding, (4) uptake of hydrogen in the event that the cladding oxide layer is dissolved in a steam-starved region, (5) embrittlement of cladding due to hydrogen uptake, (6) cracking of cladding during quenching due to its embrittlement and (7) release of hydrogen from the cladding after cracking of the cladding. An integral diffusion method is described for calculating the diffusion processes in the cladding. Experimental results are presented that show a rapid uptake of hydrogen in the event of dissolution of the oxide layer and a rapid release of hydrogen in the event of cracking of the oxide layer. These experimental results are used as a basis for calculating the rate of hydrogen uptake and the rate of hydrogen release. The uptake of hydrogen is limited to the equilibrium solubility calculated by applying Sievert's law. The uptake of hydrogen is an exothermic reaction that accelerates the heatup of a fuel rod. An embrittlement criteria is described that accounts for hydrogen and oxygen concentration and the extent of oxidation. A design is described for implementing the models for hydrogen and oxygen uptake and cladding embrittlement into the programming framework of the SCDAP/RELAP5 code. A test matrix is described for assessing the impact of the proposed models on the calculated behavior of fuel rods in severe accident conditions. This report is a revision and reissue of the report entitled; ``Preliminary Design Report for Modeling of Hydrogen Uptake in Fuel Rod Cladding During Severe Accidents.''

  2. Modified Dietary Fiber from Cassava Pulp and Assessment of Mercury Bioaccessibility and Intestinal Uptake Using an In Vitro Digestion/Caco-2 Model System.

    PubMed

    Kachenpukdee, Natta; Santerre, Charles R; Ferruzzi, Mario G; Oonsivilai, Ratchadaporn

    2016-07-01

    The ability of modified dietary fiber (MDF) generated from cassava pulp to modulate the bioaccessibility and intestinal absorption of heavy metals may be helpful to mitigate health risk associated with select foods including select fish high in methyl mercury. Using a coupled in vitro digestion/Caco-2 human intestinal cell model, the reduction of fish mercury bioaccessibility and intestinal uptake by MDF was investiaged. MDF was prepared from cassava pulp, a byproduct of tapioca production. The highest yield (79.68%) of MDF was obtained by enzymatic digestion with 0.1% α-amylase (w/v), 0.1% amyloglucosidase (v/v) and 1% neutrase (v/v). MDF and fish tissue were subjected to in vitro digestion and results suggest that MDF may reduce mercury bioaccessibility from fish to 34% to 85% compared to control in a dose-dependent manner. Additionally, accumulation of mercury from digesta containing fish and MDF was only modestly impacted by the presence of MDF. In conclusion, MDF prepared from cassava pulp may be useful as an ingredient to reduce mercury bioavailability from food such as fish specifically by inhibiting mercury transfer to the bioaccessibile fraction during digestion. PMID:27220052

  3. Improved vitamin B(12) production by step-wise reduction of oxygen uptake rate under dissolved oxygen limiting level during fermentation process.

    PubMed

    Wang, Ze-Jian; Wang, Hui-Yuan; Li, Yong-Liang; Chu, Ju; Huang, Ming-Zhi; Zhuang, Ying-Ping; Zhang, Si-Liang

    2010-04-01

    Effects of different oxygen transfer rates (OTR) on the cell growth and vitamin B(12) biosynthesis of Pseudomonas denitrificans were first investigated under dissolved oxygen limiting conditions. The results demonstrated that high OTR accelerated cell growth and initial vitamin B(12) biosynthesis rate, while lower OTR was critical for higher productivity in the late fermentation process. The oxygen uptake rates (OUR) corresponded well with OTR. Based on the metabolic intermediate analysis, a step-wise OUR control strategy was proposed. The strategy was successfully implemented in scale-up to an industrial fermenter (120,000 l). A stable maximum vitamin B(12) production of 208 + or - 2.5 mg/l was achieved, which was increased by 17.3% compared with the control. Furthermore, the glucose consumption coefficient to vitamin B(12) was 34.4% lower than that of the control. An efficient and economical fermentation process based on OUR criterion was established for industrial vitamin B(12) fermentation by P. denitrificans. PMID:20022743

  4. Calculation of hydrogen and oxygen uptake in fuel rod cladding during severe accidents using the integral diffusion method -- Final Design Report

    SciTech Connect

    Siefken, L.J.

    1999-05-01

    Final designs are described for models of hydrogen and oxygen uptake in fuel rod cladding during severe accidents. Calculation of the uptake involves the modeling of seven processes: (1) diffusion of oxygen from the bulk gas into the boundary layer at the external cladding surface, (2) diffusion from the boundary layer into the oxide layer, (3) diffusion from the inner surface of the oxide layer into the metallic part of the cladding, (4) uptake of hydrogen in the event that the cladding oxide layer is dissolved in a steam-starved region, (5) embrittlement of cladding due to hydrogen uptake, (6) cracking of cladding during quenching due to its embrittlement and (7) release of hydrogen from the cladding after cracking of the cladding. An integral diffusion method is described for calculating the diffusion processes in the cladding. Experimental results are presented that show a rapid uptake of hydrogen in the event of dissolution of the oxide layer and a rapid release of hydrogen in the event of cracking of the oxide layer. These experimental results are used as a basis for calculating the rate of hydrogen uptake and the rate of hydrogen release. A description is given of the implementation of the models for hydrogen and oxygen uptake and cladding embrittlement into the programming framework of the SCDAP/RELAP5/MOD3.3 code.

  5. Calculation of Hydrogen and Oxygen Uptake in Fuel Rod Cladding During Severe Accidents Using the Integral Diffusion Method - Final Design Report

    SciTech Connect

    Siefken, Larry James

    1999-06-01

    Final designs are described for models of hydrogen and oxygen uptake in fuel rod cladding during severe accidents. Calculation of the uptake involves the modeling of seven processes: (1) diffusion of oxygen from the bulk gas into the boundary layer at the external cladding surface, (2) diffusion from the boundary layer into the oxide layer, (3) diffusion from the inner surface of the oxide layer into the metallic part of the cladding, (4) uptake of hydrogen in the event that the cladding oxide layer is dissolved in a steam-starved region, (5) embrittlement of cladding due to hydrogen uptake, (6) cracking of cladding during quenching due to its embrittlement and (7) release of hydrogen from the cladding after cracking of the cladding. An integral diffusion method is described for calculating the diffusion processes in the cladding. Experimental results are presented that show a rapid uptake of hydrogen in the event of dissolution of the oxide layer and a rapid release of hydrogen in the event of cracking of the oxide layer. These experimental results are used as a basis for calculating the rate of hydrogen uptake and the rate of hydrogen release. A description is given of the implementation of the models for hydrogen and oxygen uptake and cladding embrittlement into the programming framework of the SCDAP/RELAP5/MOD3.3 code.

  6. Oxygen uptake from aquatic macrophyte decomposition from Piraju Reservoir (Piraju, SP, Brazil).

    PubMed

    Bianchini Jr, I; Cunha-Santino, M B; Panhota, R S

    2011-02-01

    The kinetics of oxygen consumption related to mineralisation of 18 taxa of aquatic macrophytes (Cyperus sp, Azolla caroliniana, Echinodorus macrophyllus, Eichhornia azurea, Eichhornia crassipes, Eleocharis sp1, Eleocharis sp2, Hetereanthera multiflora, Hydrocotyle raniculoides, Ludwigia sp, Myriophyllum aquaticum, Nymphaea elegans, Oxycaryum cubense, Ricciocarpus natans, Rynchospora corymbosa, Salvinia auriculata, Typha domingensis and Utricularia foliosa) from the reservoir of Piraju Hydroelectric Power Plant (São Paulo state, Brazil) were described. For each species, two incubations were prepared with ca. 300.0 mg of plant (DW) and 1.0 L of reservoir water sample. The incubations were maintained in the dark and at 20 ºC. Periodically the dissolved oxygen (DO) concentrations were measured; the accumulated DO values were fitted to 1st order kinetic model and the results showed that: i) high oxygen consumption was observed for Ludwigia sp (533 mg g-1 DW), while the lowest was registered for Eleocharis sp1 (205 mg g-1 DW) mineralisation; ii) the higher deoxygenation rate constants were verified in the mineralisation of A. caroliniana (0.052 day-1), H. raniculoides (0.050 day-1) and U. foliosa (0.049 day-1). The oxygen consumption rate constants of Ludwigia sp and Eleocharis sp2 mineralisation (0.027 day-1) were the lowest. The half-time of oxygen consumption varied from 9 to 26 days. In the short term, the detritus of E. macrophyllus, H. raniculoides, Ludwigia sp, N. elegans and U. foliosa were the critical resources to the reservoir oxygen demand; while in the long term, A. caroliniana, H. multiflora and T. domingensis were the resources that can potentially contribute to the benthic oxygen demand of this reservoir. PMID:21437396

  7. Myocardial uptake of thallium and rubidium during alterations in perfusion and oxygenation in isolated rabbit hearts

    SciTech Connect

    Leppo, J.A.

    1987-05-01

    The comparative effects of altered cellular function and coronary perfusion on myocardial /sup 201/Tl and /sup 83/Rb uptake were evaluated in three groups of isolated rabbit hearts having isovolumic contractions. Paired-indication dilution experiments were performed with /sup 201/Tl, /sup 83/Rb, and /sup 111/In-labeled albumin as an intravascular reference marker. In Group A hearts (n = 12), isotope transport was determined during control, hypoxia, and ischemia. In Group B hearts (n = 8), isotope transport was measured at control flow and again at a 50% and 80% reduction. In Group C hearts (n = 8) only /sup 201/Tl uptake was determined at control and following coronary reperfusion. Myocardial /sup 201/Tl and /sup 83/Rb transport were not significantly different and were proportional to flow. Although all interventions caused significant hemodynamic alterations, neither tracer was affected by hypoxia at constant flow. Thallium-201 permeation, however, was transiently decreased immediately after coronary reperfusion. We conclude that myocardial uptake of /sup 201/Tl and /sup 83/Rb are similar and directly related to flow, but do not reflect hypoxia induced cellular dysfunction.

  8. Effects of continuous vs interval exercise training on oxygen uptake efficiency slope in patients with coronary artery disease

    PubMed Central

    Prado, D.M.L.; Rocco, E.A.; Silva, A.G.; Rocco, D.F.; Pacheco, M.T.; Silva, P.F.; Furlan, V.

    2016-01-01

    The oxygen uptake efficiency slope (OUES) is a submaximal index incorporating cardiovascular, peripheral, and pulmonary factors that determine the ventilatory response to exercise. The purpose of this study was to evaluate the effects of continuous exercise training and interval exercise training on the OUES in patients with coronary artery disease. Thirty-five patients (59.3±1.8 years old; 28 men, 7 women) with coronary artery disease were randomly divided into two groups: continuous exercise training (n=18) and interval exercise training (n=17). All patients performed graded exercise tests with respiratory gas analysis before and 3 months after the exercise-training program to determine ventilatory anaerobic threshold (VAT), respiratory compensation point, and peak oxygen consumption (peak VO2). The OUES was assessed based on data from the second minute of exercise until exhaustion by calculating the slope of the linear relation between oxygen uptake and the logarithm of total ventilation. After the interventions, both groups showed increased aerobic fitness (P<0.05). In addition, both the continuous exercise and interval exercise training groups demonstrated an increase in OUES (P<0.05). Significant associations were observed in both groups: 1) continuous exercise training (OUES and peak VO2 r=0.57; OUES and VO2 VAT r=0.57); 2) interval exercise training (OUES and peak VO2 r=0.80; OUES and VO2 VAT r=0.67). Continuous and interval exercise training resulted in a similar increase in OUES among patients with coronary artery disease. These findings suggest that improvements in OUES among CAD patients after aerobic exercise training may be dependent on peripheral and central mechanisms. PMID:26871969

  9. Oxygen consumption and labile dissolved organic carbon uptake by benthic biofilms

    NASA Astrophysics Data System (ADS)

    de Falco, Natalie; Boano, Fulvio; Arnon, Shai

    2015-04-01

    Biogeochemical activity in streams is often magnified at interfaces, such as in the case of biofilm growth near the surface of the stream sediments. The objective of this study was to evaluate the relative importance of surficial biofilms versus the biofilm in the hyporheic zone to the processes of biodegradation of a labile dissolved organic carbon (DOC) and to oxygen consumption. Experiments were conducted in a recirculating flume, equipped with a drainage system that enables the control on losing and gaining fluxes. A surficial biofilm was developed over a sandy streambed with dune-shaped bed forms, by providing labile DOC (sodium benzoate) and nitrate. Homogeneously distributed biofilm was obtained by the same feeding strategy but with mixing the sediments manually on a daily basis. After the biofilm growth period, transformation of the labile DOC under different overlying velocities and losing or gaining fluxes was studied after spiking with sodium benzoate and by monitoring the decrease in DOC concentration in the bulk water over time using an online UV/Vis spectrophotometer. In addition, oxygen profiles across the water-streambed interface were measured at different locations along the bed form using oxygen microelectrodes. Preliminary results showed that the rate of labile DOC degradation increased exponentially with increasing overlying water velocity, regardless of the type of biofilm. Gaining and losing conditions did not play a critical role in the DOC degradation regardless of the type of biofilm, because the labile DOC was quickly utilized close to the surface. Under losing conditions, complete depletion of oxygen was observed within the top 5 millimeters, regardless of the biofilm type. In contrast, oxygen profiles under gaining condition showed an incomplete consumption of oxygen followed by an increase in the concentration of oxygen deeper in the sediments due to the upward flow of oxygenated groundwater. The results suggest that the transformation

  10. Intestinal circulation during inhalation anesthesia

    SciTech Connect

    Tverskoy, M.; Gelman, S.; Fowler, K.C.; Bradley, E.L.

    1985-04-01

    This study was designed to evaluate the influence of inhalational agents on the intestinal circulation in an isolated loop preparation. Sixty dogs were studied, using three intestinal segments from each dog. Selected intestinal segments were pumped with aortic blood at a constant pressure of 100 mmHg. A mixture of /sub 86/Rb and 9-microns spheres labeled with /sup 141/Ce was injected into the arterial cannula supplying the intestinal loop, while mesenteric venous blood was collected for activity counting. A very strong and significant correlation was found between rubidium clearance and microsphere entrapment (r = 0.97, P less than 0.0001). Nitrous oxide anesthesia was accompanied by a higher vascular resistance (VR), lower flow (F), rubidium clearance (Cl-Rb), and microspheres entrapment (Cl-Sph) than pentobarbital anesthesia, indicating that the vascular bed in the intestinal segment was constricted and flow (total and nutritive) decreased. Halothane, enflurane, and isoflurane anesthesia were accompanied by a much lower arteriovenous oxygen content difference (AVDO/sub 2/) and oxygen uptake than pentobarbital or nitrous oxide. Compared with pentobarbital, enflurane anesthesia was not accompanied by marked differences in VR, F, Cl-Rb, and Cl-Sph; halothane at 2 MAC decreased VR and increased F and Cl-Rb while isoflurane increased VR and decreased F. alpha-Adrenoceptor blockade with phentolamine (1 mg . kg-1) abolished isoflurane-induced vasoconstriction, suggesting that the increase in VR was mediated via circulating catecholamines.

  11. Cell uptake, intracellular distribution, fate and reactive oxygen species generation of polymer brush engineered CeO2-x NPs

    NASA Astrophysics Data System (ADS)

    Qiu, Yuan; Rojas, Elena; Murray, Richard A.; Irigoyen, Joseba; Gregurec, Danijela; Castro-Hartmann, Pablo; Fledderman, Jana; Estrela-Lopis, Irina; Donath, Edwin; Moya, Sergio E.

    2015-04-01

    Cerium Oxide nanoparticles (CeO2-x NPs) are modified with polymer brushes of negatively charged poly (3-sulfopropylmethacrylate) (PSPM) and positively charged poly (2-(methacryloyloxy)ethyl-trimethylammonium chloride) (PMETAC) by Atom Transfer Radical Polymerisation (ATRP). CeO2-x NPs are fluorescently labelled by covalently attaching Alexa Fluor® 488/Fluorescein isothiocyanate to the NP surface prior to polymerisation. Cell uptake, intracellular distribution and the impact on the generation of intracellular Reactive Oxygen Species (ROS) with respect to CeO2-x NPs are studied by means of Raman Confocal Microscopy (CRM), Transmission Electron Microscopy (TEM) and Inductively Coupled Plasma Mass Spectroscopy (ICP-MS). PSPM and PMETAC coated CeO2-x NPs show slower and less uptake compared to uncoated Brush modified NPs display a higher degree of co-localisation with cell endosomes and lysosomes after 24 h of incubation. They also show higher co-localisation with lipid bodies when compared to unmodified CeO2-x NPs. The brush coating does not prevent CeO2-x NPs from displaying antioxidant properties.Cerium Oxide nanoparticles (CeO2-x NPs) are modified with polymer brushes of negatively charged poly (3-sulfopropylmethacrylate) (PSPM) and positively charged poly (2-(methacryloyloxy)ethyl-trimethylammonium chloride) (PMETAC) by Atom Transfer Radical Polymerisation (ATRP). CeO2-x NPs are fluorescently labelled by covalently attaching Alexa Fluor® 488/Fluorescein isothiocyanate to the NP surface prior to polymerisation. Cell uptake, intracellular distribution and the impact on the generation of intracellular Reactive Oxygen Species (ROS) with respect to CeO2-x NPs are studied by means of Raman Confocal Microscopy (CRM), Transmission Electron Microscopy (TEM) and Inductively Coupled Plasma Mass Spectroscopy (ICP-MS). PSPM and PMETAC coated CeO2-x NPs show slower and less uptake compared to uncoated Brush modified NPs display a higher degree of co-localisation with cell

  12. Calibration of simultaneous measurements of photosynthetic carbon dioxide uptake and oxygen evolution in leaves.

    PubMed

    Oja, Vello; Eichelmann, Hillar; Laisk, Agu

    2007-01-01

    The stoichiometric ratio of O2 evolution to CO2 uptake during photosynthesis reveals information about reductive metabolism, including the reduction of alternative electron acceptors, such as nitrite and oxaloacetate. Recently we reported that in simultaneous measurements of CO2 uptake and O2 evolution in a sunflower leaf, O2 evolution changed by 7% more than CO2 uptake when light intensity was varied. Since the O2/CO2 exchange ratio is approximately 1, small differences are important. Thus, these gas exchange measurements need precise calibration. In this work, we describe a new calibration procedure for such simultaneous measurements, based on the changes of O2 concentration caused by the addition of pure CO2 or O2 into a flow of dry air (20.95% O2) through one and the same capillary. The relative decrease in O2 concentration during the addition of CO2 and the relative increase in O2 concentration during the addition of O2 allowed us to calibrate the CO2 and O2 scales of the measurement system with an error (relative standard deviation, RSD) of <1%. Measurements on a sunflower leaf resulted in an O2/CO2 ratio between 1.0 and 1.03 under different CO2 concentrations and light intensities, in the presence of an ambient O2 concentration of 20-50 micromol mol(-1). This shows that the percentage use of reductive power from photochemistry in synthesis of inorganic or organic matter other than CO2 assimilation in the C3 cycle is very low in mature leaves and, correspondingly, the reduction of alternative acceptors is a weak source of coupled ATP synthesis. PMID:17169918

  13. Maximal oxygen uptake is proportional to muscle fiber oxidative capacity, from chronic heart failure patients to professional cyclists.

    PubMed

    van der Zwaard, Stephan; de Ruiter, Jo C; Noordhof, Dionne A; Sterrenburg, Renske; Bloemers, Frank W; de Koning, Jos J; Jaspers, Richard T; van der Laarse, Willem J

    2016-09-01

    V̇o2 max during whole body exercise is presumably constrained by oxygen delivery to mitochondria rather than by mitochondria's ability to consume oxygen. Humans and animals have been reported to exploit only 60-80% of their mitochondrial oxidative capacity at maximal oxygen uptake (V̇o2 max). However, ex vivo quantification of mitochondrial overcapacity is complicated by isolation or permeabilization procedures. An alternative method for estimating mitochondrial oxidative capacity is via enzyme histochemical quantification of succinate dehydrogenase (SDH) activity. We determined to what extent V̇o2 max attained during cycling exercise differs from mitochondrial oxidative capacity predicted from SDH activity of vastus lateralis muscle in chronic heart failure patients, healthy controls, and cyclists. V̇o2 max was assessed in 20 healthy subjects and 28 cyclists, and SDH activity was determined from biopsy cryosections of vastus lateralis using quantitative histochemistry. Similar data from our laboratory of 14 chronic heart failure patients and 6 controls were included. Mitochondrial oxidative capacity was predicted from SDH activity using estimated skeletal muscle mass and the relationship between ex vivo fiber V̇o2 max and SDH activity of isolated single muscle fibers and myocardial trabecula under hyperoxic conditions. Mitochondrial oxidative capacity predicted from SDH activity was related (r(2) = 0.89, P < 0.001) to V̇o2 max measured during cycling in subjects with V̇o2 max ranging from 9.8 to 79.0 ml·kg(-1)·min(-1) V̇o2 max measured during cycling was on average 90 ± 14% of mitochondrial oxidative capacity. We conclude that human V̇o2 max is related to mitochondrial oxidative capacity predicted from skeletal muscle SDH activity. Mitochondrial oxidative capacity is likely marginally limited by oxygen supply to mitochondria. PMID:27445298

  14. Alterations of oxygen uptake and the redox state of ubiquinone in rabbit sperm exposed to a variety of physiologic treatments.

    PubMed

    Killian, G J; Gelerinter, E; Chapman, D A

    1985-11-01

    The rate of TEMPONE reduction by electrons originating from ubiquinone in intact rabbit spermatozoa was observed for control, high ionic strength (HIS) medium-treated, and HIS-seminal plasma-treated (HIS-SP) samples. The presence of TEMPONE in the incubation medium had no effect on oxygen consumption, demonstrating the utility of TEMPONE as a nonperturbing probe of the ubiquinol redox state. The rate of TEMPONE reduction was significantly increased over control levels for sperm incubated in hypertonic medium and was correlated to a decrease in oxygen consumption and a relative increase in ATP in the total adenine nucleotide pool. This increase in TEMPONE reduction in HIS sperm was reversed by treatment of sperm with seminal plasma, but seminal plasma had no effect on oxygen consumption or relative amounts of ATP in the adenine nucleotide pool. These observations are consistent with state 3 respiration in control sperm and state 4 respiration in HIS- and HIS-SP-treated sperm. Arrhenius data were obtained for ejaculated and epididymal sperm subjected to a variety of treatments. Lines fitted to plots of Arrhenius data revealed that each treatment affected the activation energy and intercept relative to controls. Evidence is presented for a phase transition occurring at 13 degrees C based on changes in the rate of TEMPONE reduction by ubiquinol. It was noted that, above the phase transition, rate constants for the reaction were dependent upon both treatment and temperature, but below the transition the differential effects of treatment were no longer apparent. The present study has demonstrated that events taking place in the respiratory chain can be closely monitored by measuring oxygen uptake and TEMPONE reduction, and that these events are affected by alterations in the sperm environment. PMID:4084632

  15. Oxygen uptake by excised gills of Procambarus clarkii (Girard) from Albufera Lake of Valencia, Spain, under heavy metal treatments

    SciTech Connect

    Diaz-Mayans, J.; Torreblanca, A.; Del Ramo, J.; Nunez, A.

    1986-06-01

    The American red crayfish Procambarus clarkii, originally from Louisiana (USA) was introduced in Spain in the 70's in the Guadalquivir River swamps. It appeared first randomly and in a more regular basis afterwards since 1978 in the Albufera Lake south of Valencia and in the surrounding rice fields. Albufera lake and surrounding rice fields waters are being subject since the last three decades to very heavy load of sewage, toxic industrial residues including heavy metals and pesticides from the many urban and industrial settlements in the zone. In the present study, the authors have investigated the effect that heavy metals (Chromium, Cadmium and Mercury) have on the oxygen uptake by excised bills of Procambarus clarkii (Girard) coming from the Albufera Lake (Valencia).

  16. Athletic Differences in the Characteristics of the Photoplethysmographic Pulse Shape: Effect of Maximal Oxygen Uptake and Maximal Muscular Voluntary Contraction

    PubMed Central

    Wang, Anran; Yang, Lin; Liu, Chengyu; Cui, Jingxuan; Li, Yao; Yang, Xingxing; Zhang, Song

    2015-01-01

    This study aimed to investigate the athletic differences in the characteristics of the photoplethysmographic (PPG) pulse shape. 304 athletes were enrolled and divided into three subgroups according to a typical sport classification in terms of the maximal oxygen uptake (MaxO2_low, MaxO2_middle and MaxO2_high groups) or the maximal muscular voluntary contraction (MMVC_low, MMVC_middle, and MMVC_high groups). Finger PPG pulses were digitally recorded and then normalized to derive the pulse area, pulse peak time Tp, dicrotic notch time Tn, and pulse reflection index (RI). The four parameters were finally compared between the three subgroups categorized by MaxO2 or by MMVC. In conclusion, it has been demonstrated by quantifying the characteristics of the PPG pulses in different athletes that MaxO2, but not MMVC, had significant effect on the arterial properties. PMID:25710022

  17. Biomass characterization by dielectric monitoring of viability and oxygen uptake rate measurements in a novel membrane bioreactor.

    PubMed

    Shariati, Farshid Pajoum; Heran, Marc; Sarrafzadeh, Mohammad Hossein; Mehrnia, Mohammad Reza; Sarzana, Gabriele; Ghommidh, Charles; Grasmick, Alain

    2013-07-01

    The application of permittivity and oxygen uptake rate (OUR) as biological process control parameters in a wastewater treatment system was evaluated. Experiments were carried out in a novel airlift oxidation ditch membrane bioreactor under different organic loading rates (OLR). Permittivity as representative of activated sludge viability was measured by a capacitive on-line sensor. OUR was also measured as a representative for respirometric activity. Results showed that the biomass concentration increases with OLR and all biomass related measurements and simulators such as MLSS, permittivity, OUR, ASM1 and ASM3 almost follow the same increasing trends. The viability of biomass decreased when the OLR was reduced from 5 to 4 kg COD m(-3)d(-1). During decreasing of OLR, biomass related parameters generally decreased but not in a similar manner. Also, protein concentration in the system during OLR decreasing changed inversely with the activated sludge viability. PMID:23708851

  18. The Contribution of "Resting" Body Muscles to the Slow Component of Pulmonary Oxygen Uptake During High-Intensity Cycling

    PubMed Central

    Ozyener, Fadil; Whipp, Brian J.; Ward, Susan A.

    2012-01-01

    Oxygen uptake (VO2) kinetics during moderate constant-workrate (WR) exercise (>lactate-threshold (θL)) are well described as exponential. AboveθL, these kinetics are more complex, consequent to the development of a delayed slow component (VO2sc), whose aetiology remains controversial. To assess the extent of the contribution to the VO2sc from arm muscles involved in postural stability during cycling, six healthy subjects completed an incremental cycle-ergometer test to the tolerable limit for estimation of θL and determination of peak VO2. They then completed two constant-WR tests at 90% of θL and two at 80% of ∆ (difference between θL and VO2peak). Gas exchange variables were derived breath-by-breath. Local oxygenation profiles of the vastus lateralis and biceps brachii muscles were assessed by near-infrared spectroscopy, with maximal voluntary contractions (MVC) of the relevant muscles being performed post-exercise to provide a frame of reference for normalising the exercise-related oxygenation responses across subjects. Above supra-θL, VO2 rose in an exponential-like fashion ("phase 2), with a delayed VO2sc subsequently developing. This was accompanied by an increase in [reduced haemoglobin] relative to baseline (∆[Hb]), which attained 79 ± 13 % (mean, SD) of MVC maximum in vastus lateralis at end-exercise and 52 ± 27 % in biceps brachii. Biceps brachii ∆[Hb] was significantly correlated with VO2 throughout the slow phase. In contrast, for sub- L exercise, VO2 rose exponentially to reach a steady state with a more modest increase in vastus lateralis ∆[Hb] (30 ± 11 %); biceps brachii ∆[Hb] was minimally affected (8 ± 2 %). That the intramuscular O2 desaturation profile in biceps brachii was proportional to that for VO2sc during supra-θL cycle ergometry is consistent with additional stabilizing arm work contributing to the VO2sc. Key points The source(s) of the "slow component" component of pulmonary oxygen uptake kinetics (VO2sc) associated

  19. Effect of ship locking on sediment oxygen uptake in impounded rivers

    NASA Astrophysics Data System (ADS)

    Lorke, A.; McGinnis, D. F.; Maeck, A.; Fischer, H.

    2012-12-01

    In the majority of large river systems, flow is regulated and/or otherwise affected by operational and management activities, such as ship locking. The effect of lock operation on sediment-water oxygen fluxes was studied within a 12.9 km long impoundment at the Saar River (Germany) using eddy-correlation flux measurements. The continuous observations cover a time period of nearly 5 days and 39 individual locking events. Ship locking is associated with the generation of surges propagating back and forth through the impoundment which causes strong variations of near-bed current velocity and turbulence. These wave-induced flow variations cause variations in sediment-water oxygen fluxes. While the mean flux during time periods without lock operation was 0.5 ± 0.1 g m-2 d-1, it increased by about a factor of 2 to 1.0 ± 0.5 g m-2 d-1within time periods with ship locking. Following the daily schedule of lock operations, fluxes are predominantly enhanced during daytime and follow a pronounced diurnal rhythm. The driving force for the increased flux is the enhancement of diffusive transport across the sediment-water interface by bottom-boundary layer turbulence and perhaps resuspension. Additional means by which the oxygen budget of the impoundment is affected by lock-induced flow variations are discussed.

  20. Targeted drug delivery systems 6: Intracellular bioreductive activation, uptake and transport of an anticancer drug delivery system across intestinal Caco-2 cell monolayers.

    PubMed

    Gharat, L; Taneja, R; Weerapreeyakul, N; Rege, B; Polli, J; Chikhale, P J

    2001-05-21

    We demonstrate transport across, intracellular accumulation and bioreductive activation of a conformationally constrained, anticancer drug delivery system (the CH(3)-TDDS) using Caco-2 cell monolayers (CCMs) as an in vitro model of the human intestinal mucosa. Reverse-phase High Performance Liquid Chromatography (HPLC) coupled with UV detection was used to detect CH(3)-TDDS, the bioreduction product (lactone) and the released drug (melphalan methyl ester; MME). Upon incubation of the CH(3)-TDDS with the apical (AP) surface of 21-day-old CCM, we observed rapid decrease in the AP concentration of the CH(3)-TDDS (60%/hr) as a result of cellular uptake. Rapid intracellular accumulation of the CH(3)-TDDS was followed by bioreductive activation to deplete the cellular levels of CH(3)-TDDS. The drug part (MME) and lactone, as well as CH(3)-TDDS, were detected in the basolateral (BL) chamber. Intracellular Caco-2 levels of TDDS and lactone were also detectable. Bioreductive activation of the CH(3)-TDDS was additionally confirmed by formation of lactone after incubation of the CH(3)-TDDS in the presence of freshly prepared Caco-2 cell homogenates. During transport studies of melphalan or MME alone (as control), the intact drug was not detected in the intracellular compartment or in the BL chamber. These observations demonstrate that CH(3)-TDDS has potential for improving intestinal delivery of MME. TDDS could be useful in facilitating oral absorption of MME as well as the oral delivery of other agents. PMID:11337161

  1. A comparison of estimated maximal oxygen uptake in 9 and 10 year old schoolchildren in Tanzania and Norway

    PubMed Central

    Aandstad, A; Berntsen, S; Hageberg, R; Klasson‐Heggebø, L; Anderssen, S A

    2006-01-01

    Objective To compare estimated maximal oxygen uptake (V̇O2max) in Tanzanian and Norwegian children, by using the same bicycle protocol in both samples. Methods Maximal oxygen uptake was estimated from an indirect maximal watt cycle ergometer test in 156 rural boys and girls in Tanzania. Similarly aged urban Norwegian boys and girls (n = 379) who underwent the same test were used for comparison. The Tanzanian children also participated in a 20 metre shuttle run test and a test of bicycle skill. The Tanzanian children were tested at altitude (∼1800 metres), while the Norwegian children were tested at sea level. Results In the cycle ergometer test, estimated relative V̇O2max was similar in Tanzanian and Norwegian boys, while Tanzanian girls had 8% lower estimated V̇O2max compared with Norwegian girls (p<0.001). Only one third of the Tanzanian children were able to ride a conventional bicycle. Excluding subjects not able to ride a bicycle, there was no difference in estimated V̇O2max between Norwegian and Tanzanian children. The Tanzanian boys and girls reached significantly higher estimated V̇O2max in the shuttle run test compared with the cycle ergometer test (p<0.001). Conclusions Tanzanian and Norwegian children attained similar relative V̇O2max in the cycle ergometer test. However, the comparison was hampered by differences in altitude and the poor cycle ergometer skills in the Tanzanian children, both of which probably underestimated their V̇O2max. PMID:16556780

  2. Effect of +Gz Acceleration on the Oxygen Uptake-Excercise Load Relationship during Lower Extremity Ergometer Excercise

    NASA Technical Reports Server (NTRS)

    Jackson, Catherine G. R.

    1996-01-01

    Long term spaceflight and habitation of a space station and/or the moon require that astronauts be provided with sufficient environmental and physiological support so that they can not only function in microgravity but be returned to earth safely. As the duration of habitation in microgravity increase the effects of the concomitant deconditioning of body systems becomes a concern for added exercise in space and for reentry to Earth gravity. Many countermeasures have been proposed to maintain proper functioning of the body, but none have proved sufficient, especially when the cost of crew time spent in these activities is considered. The issue of appropriate countermeasures remains unresolved. Spaceflight deconditioning decreases tolerance to +Gz acceleration, head to foot, the direction which is experienced during reentry; the result is that the crew member is more prone to becoming pre-syncopal or syncopal, thus exacerbating the orthostatic intolerance. All ground-based research using microgravity analogues has produced this same lowered G tolerance. When intermittent exposure to +1 to +4 Gz acceleration training was used, some alleviation of orthosatic intolerance and negative physiological effects of deconditioning occurred. Exercise alone was not as effective; but the added G force was. The physiological responses to acceleration added to exercise training have not been clearly shown. We will test the hypothesis that there will be no difference in the exercise oxygen uptake-exercise load relationship with added +Gz acceleration. We wi also compare oxygen uptake during graded exercise-acceleration loads in the human-powered short arm centrifuge with those from normal supine exercise loads. The human-powered short arm centrifuge was built by NASA engineers at Ames Research Center.

  3. Maximal Aerobic Capacity and the Oxygen Uptake Efficiency Slope as Predictors of Large Artery Stiffness in Apparently Healthy Subjects

    PubMed Central

    Arena, Ross; Arrowood, James A.; Fei, Ding-Yu; Helm, Shirley; Kraft, Kenneth A.

    2009-01-01

    PURPOSE Large artery stiffness is now recognized as an important marker of cardiovascular health. The purpose of the present investigation was to assess the relationship between large artery stiffness and the oxygen uptake efficiency slope (OUES) and to determine if the OUES is a viable surrogate for maximal oxygen uptake (VO2max) in a multivariate regression analysis developed to estimate large artery stiffness. METHODS Two hundred seventy-five apparently healthy subjects (149 males; age=48.1±15.8 yrs/126 females; age=47.0±15.3 yrs) participated in this study. Subjects underwent maximal cardiopulmonary exercise testing to determine VO2max and the OUES. The OUES was calculated using 50% and 100% of the exercise data. Measurement of aortic wave velocity (AWV in meters/second) was obtained via magnetic resonance imaging. RESULTS Pearson product moment correlation analysis revealed VO2max (r = -0.49, P<.001), the OUES calculation using 50% of exercise data (r = -0.25, P<.001) and the OUES calculation using 100% of the exercise data (r = -0.34, P<.001) were all significantly related to AWV. However, only VO2max was retained in a linear regression (also including age and resting systolic blood pressure) used to predict AWV. DISCUSSION Previous research has demonstrated a relationship between VO2max and AWV, which was also found in the present study. While the OUES was significantly correlated with AWV, it does not appear to be an adequate replacement for VO2max when attempting to gauge large artery compliance. PMID:19451829

  4. Cell uptake, intracellular distribution, fate and reactive oxygen species generation of polymer brush engineered CeO(2-x) NPs.

    PubMed

    Qiu, Yuan; Rojas, Elena; Murray, Richard A; Irigoyen, Joseba; Gregurec, Danijela; Castro-Hartmann, Pablo; Fledderman, Jana; Estrela-Lopis, Irina; Donath, Edwin; Moya, Sergio E

    2015-04-21

    Cerium Oxide nanoparticles (CeO(2-x) NPs) are modified with polymer brushes of negatively charged poly (3-sulfopropylmethacrylate) (PSPM) and positively charged poly (2-(methacryloyloxy)ethyl-trimethylammonium chloride) (PMETAC) by Atom Transfer Radical Polymerisation (ATRP). CeO(2-x) NPs are fluorescently labelled by covalently attaching Alexa Fluor® 488/Fluorescein isothiocyanate to the NP surface prior to polymerisation. Cell uptake, intracellular distribution and the impact on the generation of intracellular Reactive Oxygen Species (ROS) with respect to CeO(2-x) NPs are studied by means of Raman Confocal Microscopy (CRM), Transmission Electron Microscopy (TEM) and Inductively Coupled Plasma Mass Spectroscopy (ICP-MS). PSPM and PMETAC coated CeO(2-x) NPs show slower and less uptake compared to uncoated Brush modified NPs display a higher degree of co-localisation with cell endosomes and lysosomes after 24 h of incubation. They also show higher co-localisation with lipid bodies when compared to unmodified CeO(2-x) NPs. The brush coating does not prevent CeO(2-x) NPs from displaying antioxidant properties. PMID:25789459

  5. Tracer study of oxygen and hydrogen uptake by Mg alloys in air with water vapor

    DOE PAGESBeta

    Brady, M. P.; Fayek, M.; Meyer, H. M.; Leonard, D. N.; Elsentriecy, H. H.; Unocic, K. A.; Anovitz, L. M.; Cakmak, E.; Keiser, J. R.; Song, G. L.; et al

    2015-05-15

    We studied the pure oxidation of Mg, Mg–3Al–1Zn (AZ31B), and Mg–1Zn–0.25Zr–<0.5Nd (ZE10A) at 85 °C in humid air using sequential exposures with H218O and D216O for water vapor. Incorporation of 18O in the hydroxide/oxide films indicated that oxygen from water vapor participated in the reaction. Moreover, penetration of hydrogen into the underlying metal was observed, particularly for the Zr- and Nd-containing ZE10A. Isotopic tracer profiles suggested a complex mixed inward/outward film growth mechanism.

  6. Biogeochemical cycling in an organic-rich coastal marine basin. 7. Sulfur mass balance, oxygen uptake and sulfide retention

    USGS Publications Warehouse

    Chanton, J.P.; Martens, C.S.; Goldhaber, M.B.

    1987-01-01

    Sulfur and oxygen fluxes were quantified in the seasonally varying anoxic marine sedimentary system of Cape Lookout Bight, N.C., U.S.A. Over the three year study period, 1981-1983, the mean annual sulfate reduction rate was determined to be 18.2 ?? 1.6 moles ?? m-2 ?? y-1. This value, added to the estimate of the detrital sulfur input of 1.2 ?? 4.4 gave a total sulfur input of 19.4 ?? 4.7 moles ?? m-2 ?? y-1. The sulfide flux to the sediment-water interface, measured in anaerobic benthic chambers was 4.6 ?? 0.5 moles ?? m-2 ?? y-1, and represented 37% of the annual oxygen uptake rate of 25.2 ?? 2.8 moles ?? m-2 ?? y-1. The sulfide burial rate, determined to be 15.5 ?? 3.1 moles ?? m-2 ?? y-1, was within 5% of the value predicted by summing the fluxes at the sediment-water interface. The C S weight ratio of sediment below the depth of diagenetic reaction was determined to be 2.75. The sulfide retention rate in these rapidly accumulating sediments (10 cm/yr) was 77 ?? 19%. Comparison of this result with previous studies shows that rapid sediment accumulation and the lack of bioturbation control this unusually high degree of sulfide retention. ?? 1987.

  7. Ozone uptake and formation of reactive oxygen intermediates on glassy, semi-solid and liquid organic matter

    NASA Astrophysics Data System (ADS)

    Berkemeier, Thomas; Steimer, Sarah S.; Krieger, Ulrich K.; Peter, Thomas; Pöschl, Ulrich; Ammann, Markus; Shiraiwa, Manabu

    2016-04-01

    Heterogeneous and multiphase reactions of ozone are important pathways for chemical ageing of atmospheric organic aerosols (Abbatt, Lee and Thornton, 2012). The effects of particle phase state on the reaction kinetics are still not fully elucidated and cannot be described by classical models assuming a homogeneous condensed phase (Berkemeier et al., 2013). We apply a kinetic multi-layer model, explicitly resolving gas adsorption, condensed phase diffusion and condensed phase chemistry (Shiraiwa et al., 2010), to systematic measurements of ozone uptake onto proxies for secondary organic aerosols (SOA). Our findings show how moisture-induced phase changes affect the gas uptake and chemical transformation of organic matter through change in the physicochemical properties of the substrate: the diffusion coefficients are found to be low under dry conditions, but increase by several orders of magnitude toward higher relative humidity (RH). The solubility of ozone in the dry organic matrix is found to be one order of magnitude higher than in the dilute aqueous solution. The model simulations reveal that at high RH, ozone uptake is mainly controlled by reaction throughout the particle bulk, whereas at low RH, bulk diffusion is retarded severely and reaction at the surface becomes the dominant pathway, with ozone uptake being limited by replenishment of unreacted organic molecules from the bulk phase. The experimental results can only be reconciled including a pathway for ozone self-reaction, which becomes especially important under dry and polluted conditions. Ozone self-reaction can be interpreted as formation and recombination of long-lived reactive oxygen intermediates at the aerosol surface, which could also explain several kinetic parameters and has implications for the health effects of organic aerosol particles. This study hence outlines how kinetic modelling can be used to gain mechanistic insight into the coupling of mass transport, phase changes, and chemical

  8. Hydrocarbon contamination affects deep-sea benthic oxygen uptake and microbial community composition

    NASA Astrophysics Data System (ADS)

    Main, C. E.; Ruhl, H. A.; Jones, D. O. B.; Yool, A.; Thornton, B.; Mayor, D. J.

    2015-06-01

    Accidental oil well blowouts have the potential to introduce large quantities of hydrocarbons into the deep sea and disperse toxic contaminants to midwater and seafloor areas over ocean-basin scales. Our ability to assess the environmental impacts of these events is currently impaired by our limited understanding of how resident communities are affected. This study examined how two treatment levels of a water accommodated fraction of crude oil affected the oxygen consumption rate of a natural, deep-sea benthic community. We also investigated the resident microbial community's response to hydrocarbon contamination through quantification of phospholipid fatty acids (PLFAs) and their stable carbon isotope (δ13C) values. Sediment community oxygen consumption rates increased significantly in response to increasing levels of contamination in the overlying water of oil-treated microcosms, and bacterial biomass decreased significantly in the presence of oil. Multivariate ordination of PLFA compositional (mol%) data showed that the structure of the microbial community changed in response to hydrocarbon contamination. However, treatment effects on the δ13C values of individual PLFAs were not statistically significant. Our data demonstrate that deep-sea benthic microbes respond to hydrocarbon exposure within 36 h.

  9. Oxygen uptake occurs faster than sodium pumping in bee retina after a light flash.

    PubMed

    Tsacopoulos, M; Orkand, R K; Coles, J A; Levy, S; Poitry, S

    When neurones are active there is an entry of Na+, which must subsequently be pumped out, and an increase in their oxygen consumption rate (Qo2). The Na+ pump derives its energy from ATP, splitting it into ADP and Pi, and it has reasonably been proposed that the changes in concentrations of ATP, ADP and Pi lead to a stimulation of the O2 consumption by the mitochondria and hence to a restoration of the stock of ATP. Here we present evidence suggesting that Qo2 must be controlled differently in the retinal photoreceptor cells of the honeybee drone. Stimulation of drone photoreceptors with a flash of light causes an entry of Na+ (ref. 4) and a transient increase in Qo2 that indicates respiration of the right order of magnitude to provide ATP to pump the Na+ out. We report intracellular recordings of changes in intracellular sodium (Nai+) and potassium (Ki+) in response to single light flashes and have compared the time course of extra oxygen consumption (delta Qo2) with these ion changes and other indices of Na+ pumping. We found that the time course of pumping seems to lag behind the time course of delta Qo2. It follows that the mitochondrial respiration must be stimulated by some signal which is generated earlier than the rise in ADP produced by the Na+ pump. PMID:6828139

  10. Evidence that diffusion limitation determines oxygen uptake kinetics during exercise in humans.

    PubMed Central

    Koike, A; Wasserman, K; McKenzie, D K; Zanconato, S; Weiler-Ravell, D

    1990-01-01

    To determine the role of arterial O2 content on the mechanism of muscle O2 utilization, we studied the effect of 2, 11, and 20% carboxyhemoglobin (COHb) on O2 uptake (VO2), and CO2 output (VCO2) kinetics in response to 6 min of constant moderate- and heavy-intensity cycle exercise in 10 subjects. Increased COHb did not affect resting heart rate, VO2 or VCO2. Also, the COHb did not affect the asymptotic VO2 in response to exercise. However, VO2 and VCO2 kinetics were affected differently. The time constant (TC) of VO2 significantly increased with increased COHb for both moderate and heavy work intensities. VO2 TC was positively correlated with blood lactate. In contrast, VCO2 TC was negatively correlated with increased COHb for the moderate but unchanged for the heavy work intensity. The gas exchange ratio reflected a smaller increase in CO2 stores and faster VCO2 kinetics relative to VO2 with increased COHb. These changes can be explained by compensatory cardiac output (heart rate) increase in response to reduced arterial O2 content. The selective slowing of VO2 kinetics, with decreased blood O2 content and increased cardiac output, suggests that O2 is diffusion limited at the levels of exercise studied. PMID:2122982

  11. Intestinal Phospholipid Remodeling Is Required for Dietary-Lipid Uptake and Survival on a High-Fat Diet.

    PubMed

    Wang, Bo; Rong, Xin; Duerr, Mark A; Hermanson, Daniel J; Hedde, Per Niklas; Wong, Jinny S; Vallim, Thomas Q de Aguiar; Cravatt, Benjamin F; Gratton, Enrico; Ford, David A; Tontonoz, Peter

    2016-03-01

    Phospholipids are important determinants of membrane biophysical properties, but the impact of membrane acyl chain composition on dietary-lipid absorption is unknown. Here we demonstrate that the LXR-responsive phospholipid-remodeling enzyme Lpcat3 modulates intestinal fatty acid and cholesterol absorption and is required for survival on a high-fat diet. Mice lacking Lpcat3 in the intestine thrive on carbohydrate-based chow but lose body weight rapidly and become moribund on a triglyceride-rich diet. Lpcat3-dependent incorporation of polyunsaturated fatty acids into phospholipids is required for the efficient transport of dietary lipids into enterocytes. Furthermore, loss of Lpcat3 amplifies the production of gut hormones, including GLP-1 and oleoylethanolamide, in response to high-fat feeding, contributing to the paradoxical cessation of food intake in the setting of starvation. These results reveal that membrane phospholipid composition is a gating factor in passive lipid absorption and implicate LXR-Lpcat3 signaling in a gut-brain feedback loop that couples absorption to food intake. PMID:26833026

  12. Oxygen uptake in Pacific salmon Oncorhynchus spp.: when ecology and physiology meet.

    PubMed

    Eliason, E J; Farrell, A P

    2016-01-01

    Over the past several decades, a substantial amount of research has examined how cardiorespiratory physiology supports the diverse activities performed throughout the life cycle of Pacific salmon, genus Oncorhynchus. Pioneering experiments emphasized the importance of aerobic scope in setting the functional thermal tolerance for activity in fishes. Variation in routine metabolism can have important performance and fitness consequences as it is related to dominance, aggression, boldness, territoriality, growth rate, postprandial oxygen consumption, life history, season, time of day, availability of shelter and social interactions. Wild fishes must perform many activities simultaneously (e.g. swim, obtain prey, avoid predators, compete, digest and reproduce) and oxygen delivery is allocated among competing organ systems according to the capacity of the heart to deliver blood. For example, salmonids that are simultaneously swimming and digesting trade-off maximum swimming performance in order to support the oxygen demands of digestion. As adult Pacific salmonids cease feeding in the ocean prior to their home migration, endogenous energy reserves and cardiac capacity are primarily partitioned among the demands for swimming upriver, sexual maturation and spawning behaviours. Furthermore, the upriver spawning migration is under strong selection pressure, given that Pacific salmonids are semelparous (single opportunity to spawn). Consequently, these fishes optimize energy expenditures in a number of ways: strong homing, precise migration timing, choosing forward-assist current paths and exploiting the boundary layer to avoid the strong currents in the middle of the river, using energetically efficient swimming speeds, and recovering rapidly from anaerobic swimming. Upon arrival at the spawning ground, remaining energy can be strategically allocated to the various spawning behaviours. Strong fidelity to natal streams has resulted in reproductively isolated populations that

  13. Benthic Oxygen Uptake in the Arctic Ocean Margins - A Case Study at the Deep-Sea Observatory HAUSGARTEN (Fram Strait).

    PubMed

    Cathalot, Cecile; Rabouille, Christophe; Sauter, Eberhard; Schewe, Ingo; Soltwedel, Thomas

    2015-01-01

    The past decades have seen remarkable changes in the Arctic, a hotspot for climate change. Nevertheless, impacts of such changes on the biogeochemical cycles and Arctic marine ecosystems are still largely unknown. During cruises to the deep-sea observatory HAUSGARTEN in July 2007 and 2008, we investigated the biogeochemical recycling of organic matter in Arctic margin sediments by performing shipboard measurements of oxygen profiles, bacterial activities and biogenic sediment compounds (pigment, protein, organic carbon, and phospholipid contents). Additional in situ oxygen profiles were performed at two sites. This study aims at characterizing benthic mineralization activity along local bathymetric and latitudinal transects. The spatial coverage of this study is unique since it focuses on the transition from shelf to Deep Ocean, and from close to the ice edge to more open waters. Biogeochemical recycling across the continental margin showed a classical bathymetric pattern with overall low fluxes except for the deepest station located in the Molloy Hole (5500 m), a seafloor depression acting as an organic matter depot center. A gradient in benthic mineralization rates arises along the latitudinal transect with clearly higher values at the southern stations (average diffusive oxygen uptake of 0.49 ± 0.18 mmol O2 m-2 d-1) compared to the northern sites (0.22 ± 0.09 mmol O2 m-2 d-1). The benthic mineralization activity at the HAUSGARTEN observatory thus increases southward and appears to reflect the amount of organic matter reaching the seafloor rather than its lability. Although organic matter content and potential bacterial activity clearly follow this gradient, sediment pigments and phospholipids exhibit no increase with latitude whereas satellite images of surface ocean chlorophyll a indicate local seasonal patterns of primary production. Our results suggest that predicted increases in primary production in the Arctic Ocean could induce a larger export of more

  14. Inorganic nitrate supplementation improves muscle oxygenation, O₂ uptake kinetics, and exercise tolerance at high but not low pedal rates.

    PubMed

    Bailey, Stephen J; Varnham, Richard L; DiMenna, Fred J; Breese, Brynmor C; Wylie, Lee J; Jones, Andrew M

    2015-06-01

    We tested the hypothesis that inorganic nitrate (NO3 (-)) supplementation would improve muscle oxygenation, pulmonary oxygen uptake (V̇o2) kinetics, and exercise tolerance (Tlim) to a greater extent when cycling at high compared with low pedal rates. In a randomized, placebo-controlled cross-over study, seven subjects (mean ± SD, age 21 ± 2 yr, body mass 86 ± 10 kg) completed severe-intensity step cycle tests at pedal cadences of 35 rpm and 115 rpm during separate nine-day supplementation periods with NO3 (-)-rich beetroot juice (BR) (providing 8.4 mmol NO3 (-)/day) and placebo (PLA). Compared with PLA, plasma nitrite concentration increased 178% with BR (P < 0.01). There were no significant differences in muscle oxyhemoglobin concentration ([O2Hb]), phase II V̇o2 kinetics, or Tlim between BR and PLA when cycling at 35 rpm (P > 0.05). However, when cycling at 115 rpm, muscle [O2Hb] was higher at baseline and throughout exercise, phase II V̇o2 kinetics was faster (47 ± 16 s vs. 61 ± 25 s; P < 0.05), and Tlim was greater (362 ± 137 s vs. 297 ± 79 s; P < 0.05) with BR compared with PLA. These results suggest that short-term BR supplementation can increase muscle oxygenation, expedite the adjustment of oxidative metabolism, and enhance exercise tolerance when cycling at a high, but not a low, pedal cadence in healthy recreationally active subjects. These findings support recent observations that NO3 (-) supplementation may be particularly effective at improving physiological and functional responses in type II muscle fibers. PMID:25858494

  15. Real-time monitoring of oxygen uptake in hepatic bioreactor shows CYP450-independent mitochondrial toxicity of acetaminophen and amiodarone.

    PubMed

    Prill, Sebastian; Bavli, Danny; Levy, Gahl; Ezra, Elishai; Schmälzlin, Elmar; Jaeger, Magnus S; Schwarz, Michael; Duschl, Claus; Cohen, Merav; Nahmias, Yaakov

    2016-05-01

    Prediction of drug-induced toxicity is complicated by the failure of animal models to extrapolate human response, especially during assessment of repeated dose toxicity for cosmetic or chronic drug treatments. In this work, we present a 3D microreactor capable of maintaining metabolically active HepG2/C3A spheroids for over 28 days in vitro under stable oxygen gradients mimicking the in vivo microenvironment. Mitochondrial respiration was monitored using two-frequency phase modulation of phosphorescent microprobes embedded in the tissue. Phase modulation is focus independent and unaffected by cell death or migration. This sensitive measurement of oxygen dynamics revealed important information on the drug mechanism of action and transient subthreshold effects. Specifically, exposure to antiarrhythmic agent, amiodarone, showed that both respiration and the time to onset of mitochondrial damage were dose dependent showing a TC50 of 425 μm. Analysis showed significant induction of both phospholipidosis and microvesicular steatosis during long-term exposure. Importantly, exposure to widely used analgesic, acetaminophen, caused an immediate, reversible, dose-dependent loss of oxygen uptake followed by a slow, irreversible, dose-independent death, with a TC50 of 12.3 mM. Transient loss of mitochondrial respiration was also detected below the threshold of acetaminophen toxicity. The phenomenon was repeated in HeLa cells that lack CYP2E1 and 3A4, and was blocked by preincubation with ascorbate and TMPD. These results mark the importance of tracing toxicity effects over time, suggesting a NAPQI-independent targeting of mitochondrial complex III might be responsible for acetaminophen toxicity in extrahepatic tissues. PMID:26041127

  16. Benthic Oxygen Uptake in the Arctic Ocean Margins - A Case Study at the Deep-Sea Observatory HAUSGARTEN (Fram Strait)

    PubMed Central

    Cathalot, Cecile; Rabouille, Christophe; Sauter, Eberhard; Schewe, Ingo; Soltwedel, Thomas

    2015-01-01

    The past decades have seen remarkable changes in the Arctic, a hotspot for climate change. Nevertheless, impacts of such changes on the biogeochemical cycles and Arctic marine ecosystems are still largely unknown. During cruises to the deep-sea observatory HAUSGARTEN in July 2007 and 2008, we investigated the biogeochemical recycling of organic matter in Arctic margin sediments by performing shipboard measurements of oxygen profiles, bacterial activities and biogenic sediment compounds (pigment, protein, organic carbon, and phospholipid contents). Additional in situ oxygen profiles were performed at two sites. This study aims at characterizing benthic mineralization activity along local bathymetric and latitudinal transects. The spatial coverage of this study is unique since it focuses on the transition from shelf to Deep Ocean, and from close to the ice edge to more open waters. Biogeochemical recycling across the continental margin showed a classical bathymetric pattern with overall low fluxes except for the deepest station located in the Molloy Hole (5500 m), a seafloor depression acting as an organic matter depot center. A gradient in benthic mineralization rates arises along the latitudinal transect with clearly higher values at the southern stations (average diffusive oxygen uptake of 0.49 ± 0.18 mmol O2 m-2 d-1) compared to the northern sites (0.22 ± 0.09 mmol O2 m-2 d-1). The benthic mineralization activity at the HAUSGARTEN observatory thus increases southward and appears to reflect the amount of organic matter reaching the seafloor rather than its lability. Although organic matter content and potential bacterial activity clearly follow this gradient, sediment pigments and phospholipids exhibit no increase with latitude whereas satellite images of surface ocean chlorophyll a indicate local seasonal patterns of primary production. Our results suggest that predicted increases in primary production in the Arctic Ocean could induce a larger export of more

  17. Tracer study of oxygen and hydrogen uptake by Mg alloys in air with water vapor

    SciTech Connect

    Brady, M. P.; Fayek, M.; Meyer, H. M.; Leonard, D. N.; Elsentriecy, H. H.; Unocic, K. A.; Anovitz, L. M.; Cakmak, E.; Keiser, J. R.; Song, G. L.; Davis, B.

    2015-05-15

    We studied the pure oxidation of Mg, Mg–3Al–1Zn (AZ31B), and Mg–1Zn–0.25Zr–<0.5Nd (ZE10A) at 85 °C in humid air using sequential exposures with H218O and D216O for water vapor. Incorporation of 18O in the hydroxide/oxide films indicated that oxygen from water vapor participated in the reaction. Moreover, penetration of hydrogen into the underlying metal was observed, particularly for the Zr- and Nd-containing ZE10A. Isotopic tracer profiles suggested a complex mixed inward/outward film growth mechanism.

  18. Convective and Diffusive O2 Transport Components of Peak Oxygen Uptake Following Long-duration Spaceflight

    NASA Technical Reports Server (NTRS)

    Ade, Carl J.; Moore, A. D.

    2014-01-01

    Spaceflight reduces aerobic capacity and may be linked with maladaptations in the O2 transport pathway. The aim was to 1) evaluate the cardiorespiratory adaptations following 6 months aboard the International Space Station and 2) model the contributions of convective (Q (raised dot) O2) and peripheral diffusive (DO2) components of O2 transport to changes in peak O2 uptake (V (raised dot) O2PEAK). To date, 1 male astronaut (XX yrs) completed an incremental exercise test to measure V (raised dot) O2PEAK prior to and 2 days post-flight. Cardiac output (Q (raised dot) ) was measured at three submaximal work rates via carbon dioxide rebreathing. The Q (raised dot) :V (raised dot) O2 relationship was extrapolated to V (raised dot) O2PEAK to determine Q (raised dot) PEAK. Hemoglobin concentration was measured at rest via a venous blood sample. These measurements were used to model the changes in Q (raised dot) O2 and DO2 using Fick's principle of mass conservation and Law of Diffusion as established by Wagner and colleagues (Annu. Rev. Physiol 58: 21-50, 1996 and J. Appl. Physiol. 73: 1067-1076, 1992). V (raised dot) O2PEAK decreased postflight from 3.72 to 3.45 l min-1, but Q (raised dot) PEAK increased from 24.5 to 27.7 l min-1. The decrease in V (raised dot) O2PEAK post-flight was associated with a 21.2% decrease in DO2, an 18.6% decrease in O2 extraction, but a 3.4% increase in Q (raised dot) O2. These preliminary data suggest that long-duration spaceflight reduces peripheral diffusing capacity and that it largely contributes to the post-flight decrease in aerobic capacity.

  19. Carbon and Nitrogen Uptake of Calcareous Benthic Foraminifera along a Depth-Related Oxygen Gradient in the OMZ of the Arabian Sea

    PubMed Central

    Enge, Annekatrin J.; Wukovits, Julia; Wanek, Wolfgang; Watzka, Margarete; Witte, Ursula F. M.; Hunter, William R.; Heinz, Petra

    2016-01-01

    Foraminifera are an important faunal element of the benthos in oxygen-depleted settings such as Oxygen Minimum Zones (OMZs) where they can play a relevant role in the processing of phytodetritus. We investigated the uptake of phytodetritus (labeled with 13C and 15N) by calcareous foraminifera in the 0–1 cm sediment horizon under different oxygen concentrations within the OMZ in the eastern Arabian Sea. The in situ tracer experiments were carried out along a depth transect on the Indian margin over a period of 4 to 10 days. The uptake of phytodetrital carbon within 4 days by all investigated species shows that phytodetritus is a relevant food source for foraminifera in OMZ sediments. The decrease of total carbon uptake from 540 to 1100 m suggests a higher demand for carbon by species in the low-oxygen core region of the OMZ or less food competition with macrofauna. Especially Uvigerinids showed high uptake of phytodetrital carbon at the lowest oxygenated site. Variation in the ratio of phytodetrital carbon to nitrogen between species and sites indicates that foraminiferal carbon and nitrogen use can be decoupled and different nutritional demands are found between species. Lower ratio of phytodetrital carbon and nitrogen at 540 m could hint for greater demand or storage of food-based nitrogen, ingestion, or hosting of bacteria under almost anoxic conditions. Shifts in the foraminiferal assemblage structure (controlled by oxygen or food availability) and in the presence of other benthic organisms are likely to account for observed changes in the processing of phytodetritus in the different OMZ habitats. Foraminifera dominate the short-term processing of phytodetritus in the OMZ core but are less important in the lower OMZ boundary region of the Indian margin as biological interactions and species distribution of foraminifera change with depth and oxygen levels. PMID:26903959

  20. Carbon and Nitrogen Uptake of Calcareous Benthic Foraminifera along a Depth-Related Oxygen Gradient in the OMZ of the Arabian Sea.

    PubMed

    Enge, Annekatrin J; Wukovits, Julia; Wanek, Wolfgang; Watzka, Margarete; Witte, Ursula F M; Hunter, William R; Heinz, Petra

    2016-01-01

    Foraminifera are an important faunal element of the benthos in oxygen-depleted settings such as Oxygen Minimum Zones (OMZs) where they can play a relevant role in the processing of phytodetritus. We investigated the uptake of phytodetritus (labeled with (13)C and (15)N) by calcareous foraminifera in the 0-1 cm sediment horizon under different oxygen concentrations within the OMZ in the eastern Arabian Sea. The in situ tracer experiments were carried out along a depth transect on the Indian margin over a period of 4 to 10 days. The uptake of phytodetrital carbon within 4 days by all investigated species shows that phytodetritus is a relevant food source for foraminifera in OMZ sediments. The decrease of total carbon uptake from 540 to 1100 m suggests a higher demand for carbon by species in the low-oxygen core region of the OMZ or less food competition with macrofauna. Especially Uvigerinids showed high uptake of phytodetrital carbon at the lowest oxygenated site. Variation in the ratio of phytodetrital carbon to nitrogen between species and sites indicates that foraminiferal carbon and nitrogen use can be decoupled and different nutritional demands are found between species. Lower ratio of phytodetrital carbon and nitrogen at 540 m could hint for greater demand or storage of food-based nitrogen, ingestion, or hosting of bacteria under almost anoxic conditions. Shifts in the foraminiferal assemblage structure (controlled by oxygen or food availability) and in the presence of other benthic organisms are likely to account for observed changes in the processing of phytodetritus in the different OMZ habitats. Foraminifera dominate the short-term processing of phytodetritus in the OMZ core but are less important in the lower OMZ boundary region of the Indian margin as biological interactions and species distribution of foraminifera change with depth and oxygen levels. PMID:26903959

  1. Oxygen uptake kinetics during low level exercise in patients with heart failure: relation to neurohormones, peak oxygen consumption, and clinical findings

    PubMed Central

    Rocca, H; Weilenmann, D; Follath, F; Schlumpf, M; Rickli, H; Schalcher, C; Maly, F; Candinas, R; Kiowski, W

    1999-01-01

    Objective—To investigate whether oxygen uptake (V̇O2) kinetics during low intensity exercise are related to clinical signs, symptoms, and neurohumoral activation independently of peak oxygen consumption in chronic heart failure.
Design—Comparison of V̇O2 kinetics with peak V̇O2, neurohormones, and clinical signs of chronic heart failure.
Setting—Tertiary care centre.
Patients—48 patients with mild to moderate chronic heart failure.
Interventions—Treadmill exercise testing with "breath by breath" gas exchange monitoring. Measurement of atrial natriuretic factor (ANF), brain natriuretic peptide (BNP), and noradrenaline. Assessment of clinical findings by questionnaire.
Main outcome measures—O2 kinetics were defined as O2 deficit (time [rest to steady state] × ΔV̇O2 − ∑V̇O2 [rest to steady state]; normalised to body weight) and mean response time of oxygen consumption (MRT; O2 deficit/ΔV̇O2).
Results—V̇O2 kinetics were weakly to moderately correlated to the peak V̇O2 (O2 deficit, r = −0.37, p < 0.05; MRT, r = −0.49, p < 0.001). Natriuretic peptides were more closely correlated with MRT (ANF, r = 0.58; BNP, r = 0.53, p < 0.001) than with O2 deficit (ANF, r = 0.48, p = 0.001; BNP, r = 0.37, p < 0.01) or peak V̇O2 (ANF, r = −0.40; BNP, r = −0.31, p < 0.05). Noradrenaline was correlated with MRT (r = 0.33, p < 0.05) and O2 deficit (r = 0.39, p < 0.01) but not with peak V̇O2 (r = −0.20, NS). Symptoms of chronic heart failure were correlated with all indices of oxygen consumption (MRT, r = 0.47, p < 0.01; O2 deficit, r = 0.39, p < 0.01; peak V̇O2, r = −0.48, p < 0.01). Multivariate analysis showed that the correlation of V̇O2 kinetics with neurohormones and symptoms of chronic heart failure was independent of peak V̇O2 and other variables.
Conclusions—Oxygen kinetics during low intensity exercise may provide additional information over peak V̇O2 in patients

  2. The influence of tumor oxygenation on 18F-FDG (Fluorine-18 Deoxyglucose) uptake: A mouse study using positron emission tomography (PET)

    PubMed Central

    Chan, Linda W; Hapdey, Sebastien; English, Sean; Seidel, Jurgen; Carson, Joann; Sowers, Anastasia L; Krishna, Murali C; Green, Michael V; Mitchell, James B; Bacharach, Stephen L

    2006-01-01

    Background This study investigated whether changing a tumor's oxygenation would alter tumor metabolism, and thus uptake of 18F-FDG (fluorine-18 deoxyglucose), a marker for glucose metabolism using positron emission tomography (PET). Results Tumor-bearing mice (squamous cell carcinoma) maintained at 37°C were studied while breathing either normal air or carbogen (95% O2, 5% CO2), known to significantly oxygenate tumors. Tumor activity was measured within an automatically determined volume of interest (VOI). Activity was corrected for the arterial input function as estimated from image and blood-derived data. Tumor FDG uptake was initially evaluated for tumor-bearing animals breathing only air (2 animals) or only carbogen (2 animals). Subsequently, 5 animals were studied using two sequential 18F-FDG injections administered to the same tumor-bearing mouse, 60 min apart; the first injection on one gas (air or carbogen) and the second on the other gas. When examining the entire tumor VOI, there was no significant difference of 18F-FDG uptake between mice breathing either air or carbogen (i.e. air/carbogen ratio near unity). However, when only the highest 18F-FDG uptake regions of the tumor were considered (small VOIs), there was a modest (21%), but significant increase in the air/carbogen ratio suggesting that in these potentially most hypoxic regions of the tumor, 18F-FDG uptake and hence glucose metabolism, may be reduced by increasing tumor oxygenation. Conclusion Tumor 18F-FDG uptake may be reduced by increases in tumor oxygenation and thus may provide a means to further enhance 18F-FDG functional imaging. PMID:16722588

  3. Peak Oxygen Uptake during and after Long-duration Space Flight

    NASA Technical Reports Server (NTRS)

    Moore, Alan D., Jr.; Downs, Meghan E.; Lee, Stuart M. C.; Feiveson, Alan H.; Knudsen, Poul; Evetts, Simon N.; Ploutz-Snyder, Lori

    2014-01-01

    Aerobic capacity (VO2peak) previously has not been measured during or after long-duration spaceflight. PURPOSE: To measure VO2peak and submaximal exercise responses during and after International Space Station (ISS) missions. METHODS: Astronauts (9 M, 5 F: 49 +/- 5 yr, 175 +/- 7 cm, 77.2 +/- 15.1 kg, 40.6 +/- 6.4 mL/kg/min [mean +/-SD]) performed graded peak cycle tests 90 days before spaceflight, 15 d (FD15) after launch and every 30 d thereafter during flight, and 1 (R+1), 10 (R+10), and 30 d (R+30) after landing. Oxygen consumption (VO2) and heart rate (HR) were measured from rest to peak exercise, while cardiac output (Q), stroke volume (SV), and arterial-venous oxygen difference (a-vO2diff) were measured only during rest and submaximal exercise. Data were analyzed using mixed-model linear regression. Body mass contributed significantly to statistical models, and thus results are reported as modeled estimates for an average subject. RESULTS: Early inflight (FD15) VO2peak was 17% lower (95% CI = - 22%, -13%) than preflight. VO2peak increased during spaceflight (0.001 L/min/d, P = 0.02) but did not return to preflight levels. On R+1 VO2peak was 15% (95% CI = -19%, -10%) lower than preflight but recovered to within 2% of preflight by R+30 (95% CI = -6%, +3%). Peak HR was not significantly different from preflight at any time. Inflight submaximal VO2 and a-vO2diff were generally lower than preflight, but the Q vs. VO2 slope was unchanged. In contrast, the SV vs. VO2 slope was lower (P < 0.001), primarily due to elevated SV at rest, and the HR vs. VO2 slope was greater (P < 0.001), largely due to elevated HR during more intense exercise. On R+1 although the relationships between VO2 and Q, SV, and HR were not statistically different than preflight, resting and submaximal exercise SV was lower (P < 0.001), resting and submaximal exercise HR was higher (P < 0.002), and a-vO2diff was unchanged. HR and SV returned to preflight levels by R+30. CONCLUSION: In the average

  4. Predicting peak oxygen uptake from submaximal exercise after spinal cord injury.

    PubMed

    Totosy de Zepetnek, Julia O; Au, Jason S; Hol, Adrienne T; Eng, Janice J; MacDonald, Maureen J

    2016-07-01

    The purpose of this study was to determine the validity of the 6-min arm ergometry test (6MAT) in predicting peak oxygen consumption (V̇O2peak) in individuals with chronic spinal cord injury (SCI). Fifty-two individuals with chronic SCI (age, 38 ± 10 years; American Spinal Injury Association Impairment Scale (AIS), A-D; neurological level of injury (NLI), C1-L2; years post-injury (YPI), 13 ± 10 years) completed an incremental arm ergometry V̇O2peak test and a submaximal 6MAT. Oxygen consumption (V̇O2) data from both tests were used to create a predictive equation with regression analysis. Subsequently, a cross-validation group comprising an additional 10 individuals with SCI (age, 39 ± 13 years; AIS, A-D; NLI, C3-L3; YPI, 9 ± 9 years) were used to determine the predictive power of the equation. All participants were able to complete both the V̇O2peak and 6MAT assessments. Regression analysis yielded the following equation to predict V̇O2peak from end-stage 6MAT V̇O2: V̇O2peak (mL·kg(-1)·min(-1)) = 1.501(6MAT V̇O2) - 0.940. Correlation between measured and predicted V̇O2peak was excellent (r = 0.89). No significant difference was found between measured (17.41 ± 7.44 mL·kg(-1)·min(-1)) and predicted (17.42 ± 6.61 mL·kg(-1)·min(-1)) V̇O2peak (p = 0.97). When cross-validated with a sample of 10 individuals with SCI, correlation between measured and predicted V̇O2peak remained high (r = 0.89), with no differences between measured (18.81 ± 8.35 mL·kg(-1)·min(-1)) and predicted (18.73 ± 7.27 mL·kg(-1)·min(-1)) V̇O2peak (p = 0.75). Results suggest that 6MAT V̇O2 can be used to predict V̇O2peak among individuals with chronic SCI. The 6MAT should be used as a clinical tool for assessing aerobic capacity when peak exercise testing is not feasible. PMID:27363732

  5. Effects of isoleucine on glucose uptake through the enhancement of muscular membrane concentrations of GLUT1 and GLUT4 and intestinal membrane concentrations of Na+/glucose co-transporter 1 (SGLT-1) and GLUT2.

    PubMed

    Zhang, Shihai; Yang, Qing; Ren, Man; Qiao, Shiyan; He, Pingli; Li, Defa; Zeng, Xiangfang

    2016-08-01

    Knowledge of regulation of glucose transport contributes to our understanding of whole-body glucose homoeostasis and human metabolic diseases. Isoleucine has been reported to participate in regulation of glucose levels in many studies; therefore, this study was designed to examine the effect of isoleucine on intestinal and muscular GLUT expressions. In an animal experiment, muscular GLUT and intestinal GLUT were determined in weaning pigs fed control or isoleucine-supplemented diets. Supplementation of isoleucine in the diet significantly increased piglet average daily gain, enhanced GLUT1 expression in red muscle and GLUT4 expression in red muscle, white muscle and intermediate muscle (P<0·05). In additional, expressions of Na+/glucose co-transporter 1 and GLUT2 were up-regulated in the small intestine when pigs were fed isoleucine-supplemented diets (P<0·05). C2C12 cells were used to examine the expressions of muscular GLUT and glucose uptake in vitro. In C2C12 cells supplemented with isoleucine in the medium, cellular 2-deoxyglucose uptake was increased (P<0·05) through enhancement of the expressions of GLUT4 and GLUT1 (P<0·05). The effect of isoleucine was greater than that of leucine on glucose uptake (P<0·05). Compared with newborn piglets, 35-d-old piglets have comparatively higher GLUT4, GLUT2 and GLUT5 expressions. The results of this study demonstrated that isoleucine supplementation enhanced the intestinal and muscular GLUT expressions, which have important implications that suggest that isoleucine could potentially increase muscle growth and intestinal development by enhancing local glucose uptake in animals and human beings. PMID:27464458

  6. 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.

  7. A comparison of the relation between oxygen uptake and heart rate during different styles of aerobic dance and a traditional step test in women.

    PubMed

    Bell, J M; Bassey, E J

    1994-01-01

    The oxygen uptake and heart rate in various styles of dance and in a graded step test have been compared in ten healthy women aged [mean (SD)] 34 (5) years. Dance was choreographed into progressively more energetic sequences typical of community classes, and videotaped. Oxygen uptake was assessed using a respirometer carried in a back-pack. Each of the two tests (dance and step) took 15-20 min and measurements were made in randomised balanced order on the same day. The mean oxygen costs of dance ranged from 1.29 l.min-1 for low impact style to 1.83 l.min-1 for high impact style with arm work; mean heart rates were 135 and 174 beats.min-1 respectively. Low impact dance raised heart rates above 60% of predicted maximum and so would provide training; during high impact dance recorded heart rates sometimes exceeded recommended safe limits. The addition of arm work significantly increased heart rates in both high and low impact dance but when oxygen pulses for each style of dance were compared no significant differences attributable to arm work were found. Moreover calculated differences between oxygen uptakes in stepping and dance at the same heart rates (those recorded during dance) were not significant for any of the four styles. Analysis of variance confirmed that neither arm work nor impact contributed significantly to the differences, so there was no evidence that these forms of dance change the normal relation between heart rate and oxygen uptake found in dynamic activities with large muscle groups such as stepping. PMID:8162917

  8. Are the oxygen uptake and heart rate off-kinetics influenced by the intensity of prior exercise?

    PubMed

    do Nascimento Salvador, Paulo Cesar; de Aguiar, Rafael Alves; Teixeira, Anderson Santiago; Souza, Kristopher Mendes de; de Lucas, Ricardo Dantas; Denadai, Benedito Sérgio; Guglielmo, Luiz Guilherme Antonacci

    2016-08-01

    The aim of this study was to investigate the effect of prior exercise on the heart rate (HR) and oxygen uptake (VO2) off-kinetics after a subsequent high-intensity running exercise. Thirteen male futsal players (age 22.8±6.1years) performed a series of high-intensity bouts without prior exercise (control), preceded by a prior same intensity continuous exercise (CE+CE) and a prior sprint exercise (SE+CE). The magnitude of excess post-exercise oxygen consumption (EPOCm-4.25±0.19 vs. 3.69±0.20Lmin(-1) in CE+CE and 3.62±0.18Lmin(-1) in control; p<0.05) and the parasympathetic reactivation (HRR60s-33±3 vs. 37±3bpm in CE+CE and 42±3 bpm in control; p<0.05) in the SE+CE were higher and slower, compared with another two conditions. The EPOCτ (time to attain 63% of total response; 53±2s) and the heart rate time-course (HRτ-86±5s) were significantly longer after the SE+CE condition than control transition (48±2s and 69±5s, respectively; p<0.05). The SE+CE induce greater stress on the metabolic function, respiratory system and autonomic nervous system regulation during post-exercise recovery than CE, highlighting that the inclusion of sprint-based exercises can be an effective strategy to increase the total energy expenditure following an exercise session. PMID:27181327

  9. Familiarity with and uptake of alternative methods to control sheep gastro-intestinal parasites on farms in England.

    PubMed

    Moore, Hope; Pandolfi, Fanny; Kyriazakis, Ilias

    2016-05-15

    A questionnaire was distributed electronically amongst sheep farmers in England; it aimed to provide a quantification of current anthelmintic practices, farmer awareness of the issue of anthelmintic resistance (AR) and the uptake, awareness and opinions surrounding conventional and alternative methods of nematode control. The majority of farmers relied on several anthelmintics and used faecal egg counts to identify worm problems. Although farmers were aware of the issue of AR amongst helminth parasites in the UK, there was a disconnection between such awareness and on farm problems and practice of nematode control. Grazing management was used by 52% of responders, while breeding for resistance and bioactive forages by 22 and 18% respectively. Farms with more than 500 ewes, and farmers who felt nematodes were a problem, had a higher probability of using selective breeding. Farmers who considered their wormer effective, had a qualification in agriculture and whose staff did not include any family members, were more likely to use bioactive forages; the opposite was the case if farmers dosed their lambs frequently. Amongst the alternatives, highest preference was for selective breeding and vaccination, if the latter was to become commercially available, with more respondents having a preference for breeding than actually using it. Several barriers to the uptake of an alternative were identified, the most influential factor being the cost to set it up and the length of time for which it would remain effective. The disconnection between awareness of AR and practice of nematode control on farm reinforces the need for emphasising the links between the causes of AR and the consequences of strategies to address its challenge. PMID:27084464

  10. Simple exponential regression model to describe the relation between minute ventilation and oxygen uptake during incremental exercise.

    PubMed

    Baba, Reizo; Mori, Emiko; Tauchi, Nobuo; Nagashima, Masami

    2002-11-01

    The physiological significance of an exponential regression model between minute ventilation (VE) and oxygen uptake (VO2) during incremental exercise was examined. Thirty-eight subjects, including 12 patients with chronic heart failure, participated in cardiopulmonary exercise testing on a bicycle ergometer. The equation VE = a e(bVO2), where a and b are parameters, was used to describe the relation between VE and VO2 during incremental exercise. Arterialized blood gas analysis was measured before and during exercise. The correlation coefficient of the regression model was high (r = 0.97 +/- 0.02). Parameter a negatively correlated with the arterial partial pressure of carbon dioxide during exercise (r = -0.44, p < 0.01), and positively correlated with peak VO2 (r = 0.47, p < 0.01). Parameter b negatively correlated with peak VO2 (r = -0.86, p < 0.01) and positively correlated with the dead space to tidal volume ratio (r = 0.68, p < 0.01). The regression model, as well as parameters a and b, is physiologically useful in expressing metabolic response to exercise. This model, a specific solution to the differential equation dVE/dVO2 = bVE, implies that the more a subject breathes, the greater is the increment in ventilation needed to meet a further increment of metabolic demand. PMID:12580535

  11. The relationship between skeletal muscle mitochondrial citrate synthase activity and whole body oxygen uptake adaptations in response to exercise training

    PubMed Central

    Vigelsø, Andreas; Andersen, Nynne B; Dela, Flemming

    2014-01-01

    Citrate synthase (CS) activity is a validated biomarker for mitochondrial density in skeletal muscle. CS activity is also used as a biochemical marker of the skeletal muscle oxidative adaptation to a training intervention, and a relationship between changes in whole body aerobic capacity and changes in CS activity is often assumed. However, this relationship and absolute values of CS and maximal oxygen uptake (V.O2max) has never been assessed across different studies. A systematic PubMed search on literature published from 1983 to 2013 was performed. The search profile included: citrate, synthase, human, skeletal, muscle, training, not electrical stimulation, not in-vitro, not rats. Studies that reported changes in CS activity and V.O2max were included. Different training types and subject populations were analyzed independently to assess correlation between relative changes in V.O2max and CS activity. 70 publications with 97 intervention groups were included. There was a positive (r = 0.45) correlation (P < 0.001) between the relative change in V.O2max and the relative change in CS activity. All reported absolute values of CS and V.O2max did not correlate (r =- 0.07, n = 148, P = 0.4). Training induced changes in whole body oxidative capacity is matched by changes in muscle CS activity in a nearly 1:1 relationship. Absolute values of CS across different studies cannot be compared unless a standardized analytical method is used by all laboratories. PMID:25057335

  12. Measuring the activities of higher organisms in activated sludge by means of mechanical shearing pretreatment and oxygen uptake rate.

    PubMed

    Hao, Xiaodi; Wang, Qilin; Cao, Yali; van Loosdrecht, Mark C M

    2010-07-01

    A pretreatment method was developed to assess the activities of higher organisms. The method is based on mechanical shearing to damage the large cells of the protozoan and metazoan community in activated sludge. The procedure was confirmed through experimentation to be effective in determining the activities of higher organisms by comparing oxygen uptake rates (OURs) before and after the higher organisms were eradicated. Shearing led to disintegration of flocs, which could be effectively reconstituted by centrifugation. The reconstitution of the sludge flocs was essential since otherwise the activity of the floc mass would be too high due to lack of diffusion limitation. Mechanical shearing had no influence on the morphology, quantity and specific activity of yeasts, and it was inferred that bacteria smaller than yeasts in size would also not be influenced by the applied shearing procedure. Moreover, the effect of filamentous organisms on the measured activities of higher organisms was experimentally demonstrated and analyzed, and determined to be so weak that it could be ignored. Based on these tests, five typical activated sludge processes were selected to measure the contribution of higher organisms to the original OUR. The measured activities of higher organisms ranged from 9.4 to 25.0% of the original OURs. PMID:20605188

  13. Relationship between muscle blood flow and oxygen uptake during exercise in endurance-trained and untrained men.

    PubMed

    Kalliokoski, Kari K; Knuuti, Juhani; Nuutila, Pirjo

    2005-01-01

    A recent study showed good correlation between regional blood flow (BF) and oxygen uptake (Vo(2)) 30 min after exhaustive exercise. The question that remains open is whether there is similar good correlation between BF and Vo(2) also during exercise. We reanalyzed our previous data from a study in which BF and Vo(2) was measured in different quadriceps femoris muscles in seven healthy endurance-trained and seven healthy untrained men at rest and during low-intensity intermittent static knee-extension exercise (Kalliokoski KK, Oikonen V, Takala TO, Sipila H, Knuuti J, and Nuutila P. Am J Physiol Endocrinol Metab 280: E1015-E1021, 2001). When the mean values of each muscle were considered, there was good correlation between BF and Vo(2) during exercise in both groups (r(2) = 0.82 in untrained and 0.97 in trained). However, when calculated individually, the correlations were poorer, and the mean correlation coefficient (r(2)) was significantly higher in the trained men (0.71 +/- 0.07 vs. 0.40 +/- 0.11, P = 0.03). These results suggest that there is large individual variation in matching BF to Vo(2) in human skeletal muscles during exercise, ranging from very poor to excellent. Furthermore, this matching seems to be better in the endurance-trained than in untrained men. PMID:15347632

  14. PlanHab: hypoxia exaggerates the bed-rest-induced reduction in peak oxygen uptake during upright cycle ergometry.

    PubMed

    Keramidas, Michail E; Kölegård, Roger; Mekjavic, Igor B; Eiken, Ola

    2016-08-01

    The study examined the effects of hypoxia and horizontal bed rest, separately and in combination, on peak oxygen uptake (V̇o2 peak) during upright cycle ergometry. Ten male lowlanders underwent three 21-day confinement periods in a counterbalanced order: 1) normoxic bed rest [NBR; partial pressure of inspired O2 (PiO2 ) = 133.1 ± 0.3 mmHg]; 2) hypoxic bed rest (HBR; PiO2 = 90.0 ± 0.4 mmHg), and 3) hypoxic ambulation (HAMB; PiO2 = 90.0 ± 0.4 mmHg). Before and after each confinement, subjects performed two incremental-load trials to exhaustion, while inspiring either room air (AIR), or a hypoxic gas (HYPO; PiO2 = 90.0 ± 0.4 mmHg). Changes in regional oxygenation of the vastus lateralis muscle and the frontal cerebral cortex were monitored with near-infrared spectroscopy. Cardiac output (CO) was recorded using a bioimpedance method. The AIR V̇o2 peak was decreased by both HBR (∼13.5%; P ≤ 0.001) and NBR (∼8.6%; P ≤ 0.001), with greater drop after HBR (P = 0.01). The HYPO V̇o2 peak was also reduced by HBR (-9.7%; P ≤ 0.001) and NBR (-6.1%; P ≤ 0.001). Peak CO was lower after both bed-rest interventions, and especially after HBR (HBR: ∼13%, NBR: ∼7%; P ≤ 0.05). Exercise-induced alterations in muscle and cerebral oxygenation were blunted in a similar manner after both bed-rest confinements. No changes were observed in HAMB. Hence, the bed-rest-induced decrease in V̇o2 peak was exaggerated by hypoxia, most likely due to a reduction in convective O2 transport, as indicated by the lower peak values of CO. PMID:27342877

  15. Oxygen uptake, heart rate and blood lactate concentration during a normal training session of an aerobic dance class.

    PubMed

    De Angelis, M; Vinciguerra, G; Gasbarri, A; Pacitti, C

    1998-07-01

    The aim of this research was to investigate the physiological responses and, in particular, the participation of lactic acid anaerobic metabolism in aerobic dance, which is claimed to be pure aerobic exercise. In contrast to previous studies, that have put subjects in very unfamiliar situations, the parameters were monitored in the familiar context of gymnasium, practice routine and habitual instructor. A group of 30 skilled fairly well-trained women performed their usual routine, a combination of the two styles: low (LI) and high impact (HI), and were continuously monitored for heart rate (HR) and every 8 min for blood lactate concentration ([La-]b). Of the group, 15 were tested to determine their maximal aerobic power (VO2max) using a cycle-ergometer. They were also monitored during the routine for oxygen uptake (VO2) by a light telemetric apparatus. The oxygen pulses of the routine and of the corresponding exercise intensity in the incremental test were not statistically different. The mean values in the exercise session were: peak HR 92.8 (SD 7.8)% of the subject's maximal theoretical value, peak VO2 99.5 (SD 12.4)% of VO2max, maximal [La-]b 6.1 (SD 1.7) mmol x l(-1), and mean 4.8 (SD 1.3) mmol x l(-1). Repeated measures ANOVA found statistically significant differences between the increasing [La-]b values (P < 0.001). In particular, the difference between the [La-]b values at the end of the mainly LI phase and those of the LI-HI combination phase, and the difference between the samples during the combination LI-HI phase were both statistically significant (both P = 0.002 and P = 0.002). The similar oxygen pulses confirmed the validity of the present experiment design and the reliability of HR monitoring in this activity. The HR, VO2 and, above all, the increase of [La-]b to quite high values, showing a non steady state, demonstrated the high metabolic demand made by this activity that involved lactic acid metabolism at a much higher level than expected. PMID

  16. Utilization of extracorporeal membrane oxygenation alleviates intestinal ischemia-reperfusion injury in prolonged hemorrhagic shock animal model.

    PubMed

    Zhao, Liang; Luo, Lin; Chen, Jinjin; Xiao, Juan; Jia, Weikun; Xiao, Yingbin

    2014-12-01

    Intestinal ischemia-reperfusion injury is one of the main factors leading to multiple organ failure after resuscitation of prolonged hemorrhagic shock; however, the current conventional fluid resuscitation still cannot effectively reduce intestinal injury caused by prolonged hemorrhagic shock. To investigate the effect of ECMO resuscitation on alleviating intestinal ischemia-reperfusion injury in a prolonged hemorrhagic shock rabbit model. Thirty New Zealand white rabbits were randomly divided into three groups: control group, conventional fluid resuscitation group, and ECMO resuscitation group. The prolonged hemorrhagic shock model was established by keeping the arterial blood pressure from 31 to 40 mmHg for 3 h through the femoral artery bleeding, and performing the resuscitation for 2 h by conventional fluid resuscitation and ECMO resuscitation, respectively. Chiu's score of intestinal injury, serum lactate and TNF-α levels, intestinal mucosamyeloperoxidase (MPO) activity, intercellular adhesion molecule (ICAM-1), and Claudin-1expression were detected. The mean arterial blood pressure in Group 2 was significantly higher after resuscitation than in Group 1, but serum lactate and inflammatory cytokines TNF-α level were significantly lower. And Chiu's score of intestinal injury and myeloperoxidase (MPO) activity level and ICAM-1 expression were significantly lower in the ECMO resuscitation group, in which the Claudin-1 levels were significantly increased. ECMO resuscitation for the prolonged hemorrhagic shock improves tissue perfusion and reduces the systemic inflammation, and thus alleviates intestinal damage caused by prolonged hemorrhagic shock. PMID:25018149

  17. Maximal Oxygen Uptake cannot be Determined in the Incremental Phase of The Lactate Minimum Test on a Cycle Ergometer

    PubMed Central

    Miyagi, Willian Eiji; Malta, Elvis de Souza; Zagatto, Alessandro Moura

    2015-01-01

    The aim of this study was to investigate the maximal oxygen uptake (VO2MAX) determined using the incremental phase of the lactate minimum test (LM) on a cycle ergometer. Fifteen trained men were submitted to a graded exercise test (GXT) to evaluate the VO2MAX and LM. The total durations of the GXT and LM were 11.2±1.8 minutes (CI95%:10.2-12.3 minutes) and 25.3±3.2 minutes (CI95%:23.5-27.0), respectively. For the variables measured at exhaustion in both the GXT and LM, the oxygen uptake (54.6 ± 8.1 ml·kg−1·min−1vs 50.0 ± 7.7 ml·kg−1·min−1), carbon dioxide production (66.1 ± 7.5 ml·kg−1·min−1 vs 50.4 ± 8.0 ml·kg−1·min−1), ventilation (153.9 ± 19.0 L·min−1 vs 129.9 ± 22.9 L·min−1), respiratory exchange ratio (1.22 ± 0.10 vs1.01 ± 0.05), maximal power output achieved (331.6 ± 45.8 W vs 242.4 ± 41.0 W), heart rate (183.1 ± 6.9 bpm vs175.9 ± 10.6 bpm) and lactate (10.5 ± 2.3 mmol·L−1 vs 6.6 ± 2.2 mmol·L−1) were statistically lower in the LM (p < 0.05). However, the values of rating of perceived exertion (17.6 ± 2.5 for GXT and 17.2 ± 2.3 for LM) did not differ (ES = 0.12 and CV = 7.8%). There was no good agreement between the values of the VO2MAX from the GXT and VO2PEAK from the LM, as evidenced in the Bland-Altman plot (4.7 ml·kg−1·min−1 and 0.34 L·min−1 of mean differences, respectively), as well as the high values of the upper and lower limits of agreement. We conclude that the VO2PEAK values obtained in the incremental phase of the LM underestimate the VO2MAX. Key points The VO2MAX is not attained during the incremental phase of the lactate minimum test; The physiological responses at exhaustion during LM are not similar to physiological responses measured during GXT; There is a weak agreement between the peak VO2 measured at exhaustion during LM and the VO2MAX measured during GXT. PMID:25983587

  18. Maximal Oxygen Uptake cannot be Determined in the Incremental Phase of The Lactate Minimum Test on a Cycle Ergometer.

    PubMed

    Miyagi, Willian Eiji; Malta, Elvis de Souza; Zagatto, Alessandro Moura

    2015-06-01

    The aim of this study was to investigate the maximal oxygen uptake (VO2MAX) determined using the incremental phase of the lactate minimum test (LM) on a cycle ergometer. Fifteen trained men were submitted to a graded exercise test (GXT) to evaluate the VO2MAX and LM. The total durations of the GXT and LM were 11.2±1.8 minutes (CI95%:10.2-12.3 minutes) and 25.3±3.2 minutes (CI95%:23.5-27.0), respectively. For the variables measured at exhaustion in both the GXT and LM, the oxygen uptake (54.6 ± 8.1 ml·kg(-1)·min(-1) vs 50.0 ± 7.7 ml·kg(-1)·min(-1)), carbon dioxide production (66.1 ± 7.5 ml·kg(-1)·min(-1) vs 50.4 ± 8.0 ml·kg(-1)·min(-1)), ventilation (153.9 ± 19.0 L·min(-1) vs 129.9 ± 22.9 L·min(-1)), respiratory exchange ratio (1.22 ± 0.10 vs1.01 ± 0.05), maximal power output achieved (331.6 ± 45.8 W vs 242.4 ± 41.0 W), heart rate (183.1 ± 6.9 bpm vs175.9 ± 10.6 bpm) and lactate (10.5 ± 2.3 mmol·L(-1) vs 6.6 ± 2.2 mmol·L(-1)) were statistically lower in the LM (p < 0.05). However, the values of rating of perceived exertion (17.6 ± 2.5 for GXT and 17.2 ± 2.3 for LM) did not differ (ES = 0.12 and CV = 7.8%). There was no good agreement between the values of the VO2MAX from the GXT and VO2PEAK from the LM, as evidenced in the Bland-Altman plot (4.7 ml·kg(-1)·min(-1) and 0.34 L·min(-1) of mean differences, respectively), as well as the high values of the upper and lower limits of agreement. We conclude that the VO2PEAK values obtained in the incremental phase of the LM underestimate the VO2MAX. Key pointsThe VO2MAX is not attained during the incremental phase of the lactate minimum test;The physiological responses at exhaustion during LM are not similar to physiological responses measured during GXT;There is a weak agreement between the peak VO2 measured at exhaustion during LM and the VO2MAX measured during GXT. PMID:25983587

  19. The effects of hypobaric hypoxia on erythropoiesis, maximal oxygen uptake and energy cost of exercise under normoxia in elite biathletes.

    PubMed

    Czuba, Milosz; Maszczyk, Adam; Gerasimuk, Dagmara; Roczniok, Robert; Fidos-Czuba, Olga; Zając, Adam; Gołaś, Artur; Mostowik, Aleksandra; Langfort, Jozef

    2014-12-01

    The aim of the present study was to evaluate the effects of 3 weeks altitude training according to the HiHiLo (live high-base train high-interval train low) procedure as described by Chapman et al. (1998), on erythropoiesis, maximal oxygen uptake and energy cost of exercise under normoxia in elite biathletes. Fifteen male elite biathletes randomly divided into an experimental (H) group (n = 7; age 27.1 ± 4.6 years; maximal oxygen uptake (VO2max) 66.9 ± 3.3 ml·kg(-1)·min(-1); body height (BH) 1.81 ± 0.06 m; body mass (BM) 73.1 ± 5.4kg), and a control (C) group (n = 8; age 23.2 ± 0.9 years; VO2max 68.2 ± 4.1 ml·kg(-1)·min(-1); BH 1.75 ± 0.03 m; BM 63.1 ± 1.5 kg) took part in the study. The H group stayed for 3 weeks at an altitude of 2015 m and performed endurance training on skis four times per week at 3000 m. Additionally, the training protocol included three high-intensity interval sessions at an altitude of 1000 m. The C group followed the same training protocol with skirollers in normoxia at an altitude of 600 m. The HiHiLo protocol applied in our study did not change VO2max or maximal workload (WRmax) significantly during the incremental treadmill test in group H. However, the energy cost for selected submaximal workloads in group H was significantly (p < 0.01) reduced compared to group C (-5.7%, -4.4%, -6% vs. -3.5%, -2.1%, -2.4%). Also a significant (p < 0.001) increase in serum EPO levels during the first two weeks of HiHiLo training at 2015 m was observed, associated with a significant (p < 0.05) increase in hemoglobin mass, number of erythrocytes, hematocrit value and percent of reticulocytes compared with initial values (by 6.4%, 5%, 4.6% and 16,6%, respectively). In group C, changes in these variables were not observed. These positive changes observed in our study led to a conclusion that the HiHiLo training method could improve endurance in normoxia, since most of the biathlon competitions are performed at submaximal intensities. Key points

  20. Haematological rather than skeletal muscle adaptations contribute to the increase in peak oxygen uptake induced by moderate endurance training.

    PubMed

    Montero, David; Cathomen, Adrian; Jacobs, Robert A; Flück, Daniela; de Leur, Jeroen; Keiser, Stefanie; Bonne, Thomas; Kirk, Niels; Lundby, Anne-Kristine; Lundby, Carsten

    2015-10-15

    It remains unclear whether improvements in peak oxygen uptake (V̇(O2peak)) following endurance training (ET) are primarily determined by central and/or peripheral adaptations. Herein, we tested the hypothesis that the improvement in V̇(O2peak) following 6 weeks of ET is mainly determined by haematological rather than skeletal muscle adaptations. Sixteen untrained healthy male volunteers (age = 25 ± 4 years, V̇(O2peak) = 3.5 ± 0.5 l min(-1)) underwent supervised ET (6 weeks, 3-4 sessions per week). V̇(O2peak), peak cardiac output (Q̇(peak)), haemoglobin mass (Hb(mass)) and blood volumes were assessed prior to and following ET. Skeletal muscle biopsies were analysed for mitochondrial volume density (Mito(VD)), capillarity, fibre types and respiratory capacity (OXPHOS). After the post-ET assessment, red blood cell volume (RBCV) was re-established at the pre-ET level by phlebotomy and V̇(O2peak) and Q̇(peak) were measured again. We speculated that the contribution of skeletal muscle adaptations to the ET-induced increase in V̇(O2peak) would be revealed when controlling for haematological adaptations. V̇(O2peak) and Q̇(peak) were increased (P < 0.05) following ET (9 ± 8 and 7 ± 6%, respectively) and decreased (P < 0.05) after phlebotomy (-7 ± 7 and -10 ± 7%). RBCV, plasma volume and Hb(mass) all increased (P < 0.05) after ET (8 ± 4, 4 ± 6 and 6 ± 5%). As for skeletal muscle adaptations, capillary-to-fibre ratio and total Mito(VD) increased (P < 0.05) following ET (18 ± 16 and 43 ± 30%), but OXPHOS remained unaltered. Through stepwise multiple regression analysis, Q̇(peak), RBCV and Hb(mass) were found to be independent predictors of V̇(O2peak). In conclusion, the improvement in V̇(O2peak) following 6 weeks of ET is primarily attributed to increases in Q̇(peak) and oxygen-carrying capacity of blood in untrained healthy young subjects. PMID:26282186

  1. Measuring Steady-State Oxygen Uptake during the 6-Min Walk Test in Adults with Cerebral Palsy: Feasibility and Construct Validity

    ERIC Educational Resources Information Center

    Maltais, Desiree B.; Robitaille, Nancy-Michelle; Dumas, Francine; Boucher, Normand; Richards, Carol L.

    2012-01-01

    This study evaluated the feasibility of measuring steady-state oxygen uptake (V[Combining Dot Above]O[subscript 2]) during the 6-min walk test (6MWT) in adults with cerebral palsy (CP) who walk without support and whether there is construct validity for net 6MWT V[Combining Dot Above]O[subscript 2] as a measure of their walking ability.…

  2. Influence of menopause and Type 2 diabetes on pulmonary oxygen uptake kinetics and peak exercise performance during cycling.

    PubMed

    Kiely, Catherine; Rocha, Joel; O'Connor, Eamonn; O'Shea, Donal; Green, Simon; Egaña, Mikel

    2015-10-15

    We investigated if the magnitude of the Type 2 diabetes (T2D)-induced impairments in peak oxygen uptake (V̇O2) and V̇O2 kinetics was affected by menopausal status. Twenty-two women with T2D (8 premenopausal, 14 postmenopausal), and 22 nondiabetic (ND) women (11 premenopausal, 11 postmenopausal) matched by age (range = 30-59 yr) were recruited. Participants completed four bouts of constant-load cycling at 80% of their ventilatory threshold for the determination of V̇O2 kinetics. Cardiac output (CO) (inert gas rebreathing) was recorded at rest and at 30 s and 240 s during two additional bouts. Peak V̇O2 was significantly (P < 0.05) reduced in both groups with T2D compared with ND counterparts (premenopausal, 1.79 ± 0.16 vs. 1.55 ± 0.32 l/min; postmenopausal, 1.60 ± 0.30 vs. 1.45 ± 0.24 l/min). The time constant of phase II of the V̇O2 response was slowed (P < 0.05) in both groups with T2D compared with healthy counterparts (premenopausal, 29.1 ± 11.2 vs. 43.0 ± 12.2 s; postmenopausal, 33.0 ± 9.1 vs. 41.8 ± 17.7 s). At rest and during submaximal exercise absolute CO responses were lower, but the "gains" in CO larger (both P < 0.05) in both groups with T2D. Our results suggest that the magnitude of T2D-induced impairments in peak V̇O2 and V̇O2 kinetics is not affected by menopausal status in participants younger than 60 yr of age. PMID:26269520

  3. Changes in peak oxygen uptake and plasma volume in fit and unfit subjects following exposure to a simulation of microgravity

    NASA Technical Reports Server (NTRS)

    Convertino, V. A.

    1998-01-01

    To test the hypothesis that the magnitude of reduction in plasma volume and work capacity following exposure to simulated microgravity is dependent on the initial level of aerobic fitness, peak oxygen uptake (VO2peak) was measured in a group of physically fit subjects and compared with VO2peak in a group of relatively unfit subjects before and after 10 days of continuous 6 degrees head-down tilt (HDT). Ten fit subjects (40 +/- 2 year) with mean +/- SE VO2peak = 48.9 +/- 1.7 mL kg-1 min-1 were matched for age, height, and lean body weight with 10 unfit subjects (VO2peak = 37.7 +/- 1.6 mL kg-1 min-1). Before and after HDT, plasma, blood, and red cell volumes and body composition were measured and all subjects underwent a graded supine cycle ergometer test to determine VO2peak period needed. Reduced VO2peak in fit subjects (-16.2%) was greater than that of unfit subjects (-6.1%). Similarly, reductions in plasma (-18.3%) and blood volumes (-16.0%) in fit subjects were larger than those of unfit subjects (blood volume = -5.6%; plasma volume = -6.6%). Reduced plasma volume was associated with greater negative body fluid balance during the initial 24 h of HDT in the fit group (912 +/- 154 mL) compared with unfit subjects (453 +/- 200 mL). The percentage change for VO2peak correlated with percentage change in plasma volume (r = +0.79). Following exposure to simulated microgravity, fit subjects demonstrated larger reductions in VO2peak than unfit subjects which was associated with larger reductions in plasma and blood volume. These data suggest that the magnitude of physical deconditioning induced by exposure to microgravity without intervention of countermeasures was influenced by the initial fitness of the subjects.

  4. A short period of high-intensity interval training improves skeletal muscle mitochondrial function and pulmonary oxygen uptake kinetics.

    PubMed

    Christensen, Peter M; Jacobs, Robert A; Bonne, Thomas; Flück, Daniela; Bangsbo, Jens; Lundby, Carsten

    2016-06-01

    The aim of the present study was to examine whether improvements in pulmonary oxygen uptake (V̇o2) kinetics following a short period of high-intensity training (HIT) would be associated with improved skeletal muscle mitochondrial function. Ten untrained male volunteers (age 26 ± 2 yr; mean ± SD) performed six HIT sessions (8-12 × 60 s at incremental test peak power; 271 ± 52 W) over a 2-wk period. Before and after the HIT period, V̇o2 kinetics was modeled during moderate-intensity cycling (110 ± 19 W). Mitochondrial function was assessed with high-resolution respirometry (HRR), and maximal activities of oxidative enzymes citrate synthase (CS) and cytochrome c oxidase (COX) were accordingly determined. In response to HIT, V̇o2 kinetics became faster (τ: 20.4 ± 4.4 vs. 28.9 ± 6.1 s; P < 0.01) and fatty acid oxidation (ETFP) and leak respiration (LN) both became elevated (P < 0.05). Activity of CS and COX did not increase in response to training. Both before and after the HIT period, fast V̇o2 kinetics (low τ values) was associated with large values for ETFP, electron transport system capacity (ETS), and electron flow specific to complex II (CIIP) (P < 0.05). Collectively, these findings support that selected measures of mitochondrial function obtained with HRR are important for fast V̇o2 kinetics and better markers than maximal oxidative enzyme activity in describing the speed of the V̇o2 response during moderate-intensity exercise. PMID:26846547

  5. Scaling maximal oxygen uptake to predict cycling time-trial performance in the field: a non-linear approach.

    PubMed

    Nevill, A M; Jobson, S A; Palmer, G S; Olds, T S

    2005-08-01

    The purpose of the present article is to identify the most appropriate method of scaling VO2max for differences in body mass when assessing the energy cost of time-trial cycling. The data from three time-trial cycling studies were analysed (N = 79) using a proportional power-function ANCOVA model. The maximum oxygen uptake-to-mass ratio found to predict cycling speed was VO2max(m)(-0.32) precisely the same as that derived by Swain for sub-maximal cycling speeds (10, 15 and 20 mph). The analysis was also able to confirm a proportional curvilinear association between cycling speed and energy cost, given by (VO2max(m)(-0.32))0.41. The model predicts, for example, that for a male cyclist (72 kg) to increase his average speed from 30 km h(-1) to 35 km h(-1), he would require an increase in VO2max from 2.36 l min(-1) to 3.44 l min(-1), an increase of 1.08 l min(-1). In contrast, for the cyclist to increase his mean speed from 40 km h(-1) to 45 km h(-1), he would require a greater increase in VO2max from 4.77 l min(-1) to 6.36 l min(-1), i.e. an increase of 1.59 l min(-1). The model is also able to accommodate other determinants of time-trial cycling, e.g. the benefit of cycling with a side wind (5% faster) compared with facing a predominately head/tail wind (P<0.05). Future research could explore whether the same scaling approach could be applied to, for example, alternative measures of recording power output to improve the prediction of time-trial cycling performance. PMID:15906080

  6. The Correlation between Running Economy and Maximal Oxygen Uptake: Cross-Sectional and Longitudinal Relationships in Highly Trained Distance Runners

    PubMed Central

    Shaw, Andrew J.; Ingham, Stephen A.; Atkinson, Greg; Folland, Jonathan P.

    2015-01-01

    A positive relationship between running economy and maximal oxygen uptake (V̇O2max) has been postulated in trained athletes, but previous evidence is equivocal and could have been confounded by statistical artefacts. Whether this relationship is preserved in response to running training (changes in running economy and V̇O2max) has yet to be explored. This study examined the relationships of (i) running economy and V̇O2max between runners, and (ii) the changes in running economy and V̇O2max that occur within runners in response to habitual training. 168 trained distance runners (males, n = 98, V̇O2max 73.0 ± 6.3 mL∙kg-1∙min-1; females, n = 70, V̇O2max 65.2 ± 5.9 mL kg-1∙min-1) performed a discontinuous submaximal running test to determine running economy (kcal∙km-1). A continuous incremental treadmill running test to volitional exhaustion was used to determine V̇O2max 54 participants (males, n = 27; females, n = 27) also completed at least one follow up assessment. Partial correlation analysis revealed small positive relationships between running economy and V̇O2max (males r = 0.26, females r = 0.25; P<0.006), in addition to moderate positive relationships between the changes in running economy and V̇O2max in response to habitual training (r = 0.35; P<0.001). In conclusion, the current investigation demonstrates that only a small to moderate relationship exists between running economy and V̇O2max in highly trained distance runners. With >85% of the variance in these parameters unexplained by this relationship, these findings reaffirm that running economy and V̇O2max are primarily determined independently. PMID:25849090

  7. The Uptake Hydrogenase in the Unicellular Diazotrophic Cyanobacterium Cyanothece sp. Strain PCC 7822 Protects Nitrogenase from Oxygen Toxicity

    PubMed Central

    Zhang, Xiaohui; Sherman, Debra M.

    2014-01-01

    Cyanothece sp. strain PCC 7822 is a unicellular, diazotrophic cyanobacterium that can produce large quantities of H2 when grown diazotrophically. This strain is also capable of genetic manipulations and can represent a good model for improving H2 production from cyanobacteria. To this end, a knockout mutation was made in the hupL gene (ΔhupL), and we determined how this would affect the amount of H2 produced. The ΔhupL mutant demonstrated virtually no nitrogenase activity or H2 production when grown under N2-fixing conditions. To ensure that this mutation only affected the hupL gene, a complementation strain was constructed readily with wild-type properties; this indicated that the original insertion was only in hupL. The mutant had no uptake hydrogenase activity but had increased bidirectional hydrogenase (Hox) activity. Western blotting and immunocytochemistry under the electron microscope indicated that the mutant had neither HupL nor NifHDK, although the nif genes were transcribed. Interestingly, biochemical analysis demonstrated that both HupL and NifH could be membrane associated. The results indicated that the nif genes were transcribed but that NifHDK was either not translated or was translated but rapidly degraded. We hypothesized that the Nif proteins were made but were unusually susceptible to O2 damage. Thus, we grew the mutant cells under anaerobic conditions and found that they grew well under N2-fixing conditions. We conclude that in unicellular diazotrophs, like Cyanothece sp. strain PCC 7822, the HupLS complex helps remove oxygen from the nitrogenase, and that this is a more important function than merely oxidizing the H2 produced by the nitrogenase. PMID:24317398

  8. Influence of fentanyl and morphine on intestinal circulation

    SciTech Connect

    Tverskoy, M.; Gelman, S.; Fowler, K.C.; Bradley, E.L.

    1985-06-01

    The influence of fentanyl and morphine on the intestinal circulation was evaluated in an isolated loop preparation in 37 dogs anesthetized with pentobarbital intravenously. Selected intestinal segments were pumped with aortic blood at a constant pressure of 100 mm Hg. A mixture of /sup 86/Rb and 9-micron spheres labeled with /sup 141/Ce was injected into the arterial cannula supplying the intestinal loop, while mesenteric venous blood was collected for activity counting. A strong correlation was found between the clearances of rubidium and microspheres (r = 0.97, P less than 0.0001), suggesting that the shunting of 9-micron spheres through the intestines reflects the shunting of blood through nonnutritive vessels. Intravenous fentanyl decreased oxygen uptake (O/sub 2/up), and vascular resistance (VR), and increased blood flow (BF), rubidium and microsphere clearances (Cl-Rb, Cl-Sph, respectively), and permeability--surface area product (PS) in a dose-related fashion. Intravenous morphine in a dose of 1 mg X kg-1 increased Cl-Rb (nutritive BF) without changes in total (nutritive and nonnutritive) BF. This increase in nutritive BF is probably related to morphine-induced histamine release. Morphine in a dose of 5 mg X kg-1 was accompanied by vasoconstriction that was completely abolished by alpha-adrenoceptor blockade. The data suggest that morphine-induced intestinal vasoconstriction is mediated via a release of epinephrine, apparently from the adrenal medulla. It is concluded that changes in the intestinal circulation during anesthesia with narcotics might play a certain role in the cardiovascular homeostasis during anesthesia and surgery. An increase in oxygen content in portal venous blood, resulting from a decrease in intestinal oxygen uptake, should facilitate hepatic oxygenation.

  9. Effect of dl-ethionine on the intestinal absorption and transport of palmitic acid-1-14C and tripalmitin-14C. Role of intramucosal factors in the uptake of luminal lipids

    PubMed Central

    Kessler, Jacques I.; Mishkin, S.; Stein, J.

    1969-01-01

    The effect of DL-ethionine on the uptake and transport of lipid by the rat small intestine was investigated. A cottonseed oil emulsion containing 14C-labeled tripalmitin or palmitic acid was administered intragastrically to rats pretreated with DL-ethionine, DL-ethionine plus methionine, or saline, and the rats were sacrificed 2, 4, and 6 hr later. Lipids from the plasma, the stomach, the colon, the luminal contents of the small intestine, and the wall of the small intestine were extracted, fractionated, and their radioactivity assayed. Ethionine markedly inhibited the uptake of lipids by the small intestine. This inhibition was not related to impairment of intraluminal lipolysis since analagous inhibitions were observed when palmitic acid or predigested triglyceride (TG), obtained through a jejunal fistula from normal animals, was administered instead of tripalmitin. Ethionine also inhibited the transport of lipid from the wall of the small intestine. A significant fraction of the administered lipid remained in the wall of the small intestine, and only a small fraction was transported to the blood stream. Although most of the wall radioactivity was in the form of TG, significant proportions were also found in the free fatty acid (FFA) and partial glyceride fractions, indicating a marked inhibition of mucosal reesterification to TG. The degree of inhibition of mucosal reesterification and the degree of inhibition of transport of wall lipids were directly related to the degree of inhibition of uptake of luminal radioactivity. This relationship suggests that the rate of reesterification, the level of mucosal FFA, and the rate of transport of intramucosal TG may be of importance in determining the extent of uptake of intraluminal lipid by the mucosal cells. Since a significant fraction of the wall radioactivity was in the form of TG, the decreased transport of wall lipids was attributed to an impairment of chylomicron completion due to inhibition of either the

  10. Involvement of the Niacin Receptor GPR109a in the Local Control of Glucose Uptake in Small Intestine of Type 2 Diabetic Mice

    PubMed Central

    Wong, Tung Po; Chan, Leo Ka Yu; Leung, Po Sing

    2015-01-01

    Niacin is a popular nutritional supplement known to reduce the risk of cardiovascular diseases by enhancing high-density lipoprotein levels. Despite such health benefits, niacin impairs fasting blood glucose. In type 2 diabetes (T2DM), an increase in jejunal glucose transport has been well documented; however, this is intriguingly decreased during niacin deficient state. In this regard, the role of the niacin receptor GPR109a in T2DM jejunal glucose transport remains unknown. Therefore, the effects of diabetes and high-glucose conditions on GPR109a expression were studied using jejunal enterocytes of 10-week-old m+/db and db/db mice, as well as Caco-2 cells cultured in 5.6 or 25.2 mM glucose concentrations. Expression of the target genes and proteins were quantified using real-time polymerase chain reaction (RT-PCR) and Western blotting. Glucose uptake in Caco-2 cells and everted mouse jejunum was measured using liquid scintillation counting. 10-week T2DM increased mRNA and protein expression levels of GPR109a in jejunum by 195.0% and 75.9%, respectively, as compared with the respective m+/db control; high-glucose concentrations increased mRNA and protein expression of GPR109a in Caco-2 cells by 130.2% and 69.0%, respectively, which was also confirmed by immunohistochemistry. In conclusion, the enhanced GPR109a expression in jejunal enterocytes of T2DM mice and high-glucose treated Caco-2 cells suggests that GPR109a is involved in elevating intestinal glucose transport observed in diabetes. PMID:26371038

  11. Oxygen uptake, respiratory exchange ratio, or total distance: a comparison of methods to equalize exercise volume in Wistar rats

    PubMed Central

    Paes, L.S.; Borges, J.P.; Cunha, F.A.; Souza, M.G.C.; Cyrino, F.Z.G.A.; Bottino, D.A.; Bouskela, E.; Farinatti, P.

    2016-01-01

    This study compared strategies to equalize the volume of aerobic exercise performed with different intensities by Wistar rats, based on the distance covered during exercise bouts and energy expenditure (EE, isocaloric sessions) obtained from oxygen uptake (V̇O2) or respiratory exchange ratio (RER). Thirty-three male rats (270.5±12.8 g) underwent maximal exercise tests to determine V̇O2 reserve (V̇O2R), being randomly assigned to three groups: moderate-intensity continuous exercise at speed corresponding to 50% V̇O2R (MIC; n=11); high-intensity continuous exercise at 80% V̇O2R (HIC; n=11); and high-intensity intermittent exercise (HII; n=11) at 60% V̇O2R (3 min) and 80% V̇O2R (4 min). Exercise duration was calculated individually to elicit EE of 5 kcal in each session. No difference between groups was found for total running distance (MIC: 801±46, HIC: 734±42, HII: 885±64 m; P=0.13). Total EE measured by RER was systematically underestimated compared to values obtained from V̇O2 (HII: 4.5% and MIC: 6.2%, P<0.05). Total EE (calculated from V̇O2), and duration of HIC bouts (2.8 kcal and 30.8±2.2 min) were lower (P<0.0001) than in MIC (4.9 kcal and 64.7±1.8 min) and HII (4.7 kcal and 46.9±2.2 min). Predicted and actual values of total V̇O2, total EE, and duration of isocaloric sessions were similar in MIC and HII (P>0.05), which were both higher than in HIC (P<0.0001). In conclusion, the time to achieve a given EE in exercise bouts with different intensities did not correspond to the total distance. Therefore, the volume of aerobic exercise in protocols involving Wistar rats should be equalized using EE rather than total covered distance. PMID:27487418

  12. Oxygen uptake, respiratory exchange ratio, or total distance: a comparison of methods to equalize exercise volume in Wistar rats.

    PubMed

    Paes, L S; Borges, J P; Cunha, F A; Souza, M G C; Cyrino, F Z G A; Bottino, D A; Bouskela, E; Farinatti, P

    2016-07-28

    This study compared strategies to equalize the volume of aerobic exercise performed with different intensities by Wistar rats, based on the distance covered during exercise bouts and energy expenditure (EE, isocaloric sessions) obtained from oxygen uptake (V̇O2) or respiratory exchange ratio (RER). Thirty-three male rats (270.5±12.8 g) underwent maximal exercise tests to determine V̇O2 reserve (V̇O2R), being randomly assigned to three groups: moderate-intensity continuous exercise at speed corresponding to 50% V̇O2R (MIC; n=11); high-intensity continuous exercise at 80% V̇O2R (HIC; n=11); and high-intensity intermittent exercise (HII; n=11) at 60% V̇O2R (3 min) and 80% V̇O2R (4 min). Exercise duration was calculated individually to elicit EE of 5 kcal in each session. No difference between groups was found for total running distance (MIC: 801±46, HIC: 734±42, HII: 885±64 m; P=0.13). Total EE measured by RER was systematically underestimated compared to values obtained from V̇O2 (HII: 4.5% and MIC: 6.2%, P<0.05). Total EE (calculated from V̇O2), and duration of HIC bouts (2.8 kcal and 30.8±2.2 min) were lower (P<0.0001) than in MIC (4.9 kcal and 64.7±1.8 min) and HII (4.7 kcal and 46.9±2.2 min). Predicted and actual values of total V̇O2, total EE, and duration of isocaloric sessions were similar in MIC and HII (P>0.05), which were both higher than in HIC (P<0.0001). In conclusion, the time to achieve a given EE in exercise bouts with different intensities did not correspond to the total distance. Therefore, the volume of aerobic exercise in protocols involving Wistar rats should be equalized using EE rather than total covered distance. PMID:27487418

  13. The influence of metabolic and circulatory heterogeneity on the expression of pulmonary oxygen uptake kinetics in humans.

    PubMed

    Keir, Daniel A; Robertson, Taylor C; Benson, Alan P; Rossiter, Harry B; Kowalchuk, John M

    2016-01-01

    We examined the relationship amongst baseline work rate (WR), phase II pulmonary oxygen uptake (V̇(O2p)) time constant (τV̇(O2p)) and functional gain (G(P)=ΔV̇(O2p)/ΔWR) during moderate-intensity exercise. Transitions were initiated from a constant or variable baseline WR. A validated circulatory model was used to examine the role of heterogeneity in muscle metabolism (V̇(O2m)) and blood flow (Q̇(m)) in determining V̇(O2p) kinetics. We hypothesized that τV̇(O2p) and G(P) would be invariant in the constant baseline condition but would increase linearly with increased baseline WR. Fourteen men completed three to five repetitions of ∆40 W step transitions initiated from 20, 40, 60, 80, 100 and 120 W on a cycle ergometer. The ∆40 W step transitions from 60, 80, 100 and 120 W were preceded by 6 min of 20 W cycling, from which the progressive ΔWR transitions (constant baseline condition) were examined. The V̇(O2p) was measured breath by breath using mass spectrometry and a volume turbine. For a given ΔWR, both τV̇(O2p) (22-35 s) and G(P) (8.7-10.5 ml min(-1) W(-1)) increased (P < 0.05) linearly as a function of baseline WR (20-120 W). The τV̇(O2p) was invariant (P < 0.05) in transitions initiated from 20 W, but G(P) increased with ΔWR (P < 0.05). Modelling the summed influence of multiple muscle compartments revealed that τV̇(O2p) could appear fast (24 s), and similar to in vivo measurements (22 ± 6 s), despite being derived from τV̇(O2p) values with a range of 15-40 s and τQ̇(m) with a range of 20-45 s, suggesting that within the moderate-intensity domain phase II V̇(O2p) kinetics are slowed dependent on the pretransition WR and are strongly influenced by muscle metabolic and circulatory heterogeneity. PMID:26537768

  14. Slowed muscle oxygen uptake kinetics with raised metabolism are not dependent on blood flow or recruitment dynamics.

    PubMed

    Wüst, Rob C I; McDonald, James R; Sun, Yi; Ferguson, Brian S; Rogatzki, Matthew J; Spires, Jessica; Kowalchuk, John M; Gladden, L Bruce; Rossiter, Harry B

    2014-04-15

    Oxygen uptake kinetics (τVO2) are slowed when exercise is initiated from a raised metabolic rate. Whether this reflects the recruitment of muscle fibres differing in oxidative capacity, or slowed blood flow (Q) kinetics is unclear. This study determined τVO2 in canine muscle in situ, with experimental control over muscle activation and Q during contractions initiated from rest and a raised metabolic rate. The gastrocnemius complex of nine anaesthetised, ventilated dogs was isolated and attached to a force transducer. Isometric tetanic contractions (50 Hz; 200 ms duration) via supramaximal sciatic nerve stimulation were used to manipulate metabolic rate: 3 min stimulation at 0.33 Hz (S1), followed by 3 min at 0.67 Hz (S2). Circulation was initially intact (SPON), and subsequently isolated for pump-perfusion (PUMP) above the greatest value in SPON. Muscle VO2 was determined contraction-by-contraction using an ultrasonic flowmeter and venous oximeter, and normalised to tension-time integral (TTI). τVO2/TTI and τQ were less in S1SPON (mean ± s.d.: 13 ± 3 s and 12 ± 4 s, respectively) than in S2SPON (29 ± 19 s and 31 ± 13 s, respectively; P < 0.05). τVO2/TTI was unchanged by pump-perfusion (S1PUMP, 12 ± 4 s; S2PUMP, 24 ± 6 s; P < 0.001) despite increased O2 delivery; at S2 onset, venous O2 saturation was 21 ± 4% and 65 ± 5% in SPON and PUMP, respectively. VO2 kinetics remained slowed when contractions were initiated from a raised metabolic rate despite uniform muscle stimulation and increased O2 delivery. The intracellular mechanism may relate to a falling energy state, approaching saturating ADP concentration, and/or slowed mitochondrial activation; but further study is required. These data add to the evidence that muscle VO2 control is more complex than previously suggested. PMID:24469073

  15. Iron uptake and transport across physiological barriers.

    PubMed

    Duck, Kari A; Connor, James R

    2016-08-01

    Iron is an essential element for human development. It is a major requirement for cellular processes such as oxygen transport, energy metabolism, neurotransmitter synthesis, and myelin synthesis. Despite its crucial role in these processes, iron in the ferric form can also produce toxic reactive oxygen species. The duality of iron's function highlights the importance of maintaining a strict balance of iron levels in the body. As a result, organisms have developed elegant mechanisms of iron uptake, transport, and storage. This review will focus on the mechanisms that have evolved at physiological barriers, such as the intestine, the placenta, and the blood-brain barrier (BBB), where iron must be transported. Much has been written about the processes for iron transport across the intestine and the placenta, but less is known about iron transport mechanisms at the BBB. In this review, we compare the established pathways at the intestine and the placenta as well as describe what is currently known about iron transport at the BBB and how brain iron uptake correlates with processes at these other physiological barriers. PMID:27457588

  16. In vitro absorption of γ-globulin by neonatal intestinal epithelium of the pig

    PubMed Central

    Lecce, James G.

    1966-01-01

    1. An in vitro method, using fluorescent γ-globulin and everted neonatal pig's intestinal slices, for the study of the active transport of large molecules is described. 2. Uptake of γ-globulin occurred within 15 min and required no exogenous substrates. 3. In vitro absorption of γ-globulin by intestinal epithelium was limited to the neonatal pig and 5-day-old mouse. No uptake was seen in intestines from a mature mouse, a pig with diarrhoea, a normal pig, a mature rabbit, a guinea-pig, a chick, and a chick embryo. Chick embryo yolk sac readily took up γ-globulin. 4. Rings of everted intestinal epithelium remained active (still absorbed γ-globulin) after incubating for 4-6 hr in balanced salt solution (BSS). 5. Uptake of γ-globulin required oxygen and sodium and was reversibly inhibited by metabolic antagonists such as iodoacetate, arsenate, fluoride, 4,6-dinitro-ϕ-cresol, phlorrhizin, anaerobiosis and cold. Under the conditions of the test, large colloidal molecules did not inhibit uptake of γ-globulin. 6. Similar results (although not as clear-cut) with metabolic inhibitors were obtained with preparations of chick embryo yolk sacs. 7. Injuring mature pig's intestinal epithelium with surface-active agents did not produce non-specific absorption artifacts that resembled the specific absorption found in immature pig's intestinal epithelium. ImagesFig. 1Fig. 2Fig. 3Fig. 4 PMID:4164327

  17. Taurine uptake across the human intestinal brush-border membrane is via two transporters: H+-coupled PAT1 (SLC36A1) and Na+- and Cl−-dependent TauT (SLC6A6)

    PubMed Central

    Anderson, Catriona M H; Howard, Alison; Walters, Julian R F; Ganapathy, Vadivel; Thwaites, David T

    2009-01-01

    Taurine is an essential amino acid in some mammals and is conditionally essential in humans. Taurine is an abundant component of meat and fish-based foods and has been used as an oral supplement in the treatment of disorders such as cystic fibrosis and hypertension. The purpose of this investigation was to identity the relative contributions of the solute transporters involved in taurine uptake across the luminal membrane of human enterocytes. Distinct transport characteristics were revealed following expression of the candidate solute transporters in Xenopus laevis oocytes: PAT1 (SLC36A1) is a H+-coupled, pH-dependent, Na+- and Cl−-independent, low-affinity, high-capacity transporter for taurine and β-alanine; TauT (SLC6A6) is a Na+- and Cl−-dependent, high-affinity, low-capacity transporter of taurine and β-alanine; ATB0,+ (SLC6A14) is a Na+- and Cl−-dependent, high-affinity, low-capacity transporter which accepts β-alanine but not taurine. Taurine uptake across the brush-border membrane of human intestinal Caco-2 cell monolayers showed characteristics of both PAT1- and TauT-mediated transport. Under physiological conditions, Cl−-dependent TauT-mediated uptake predominates at low taurine concentrations, whereas at higher concentrations typical of diet, Cl−-independent PAT1-mediated uptake is the major absorptive mechanism. Real-time PCR analysis of human duodenal and ileal biopsy samples demonstrates that PAT1, TauT and ATB0,+ mRNA are expressed in each tissue but to varying degrees. In conclusion, this study is the first to demonstrate both taurine uptake via PAT1 and functional coexpression of PAT1 and TauT at the apical membrane of the human intestinal epithelium. PAT1 may be responsible for bulk taurine uptake during a meal whereas TauT may be important for taurine supply to the intestinal epithelium and for taurine capture between meals. PMID:19074966

  18. Systematic development of solid self-nanoemulsifying oily formulations (S-SNEOFs) for enhancing the oral bioavailability and intestinal lymphatic uptake of lopinavir.

    PubMed

    Garg, Babita; Katare, O P; Beg, Sarwar; Lohan, Shikha; Singh, Bhupinder

    2016-05-01

    The present studies entail the development of the systematically optimized solid self-nanoemulsifying oily formulations (S-SNEOFs) for enhancing the systemic bioavailability of lopinavir and targeting the same to the sanctuary site, i.e., lymphatic system for complete HIV inhibition. The patient-centric quality target product profile (QTPP) was defined and critical quality attributes (CQAs) earmarked. Risk assessment studies, carried out through failure mode and effect critically analysis (FMECA), helped in identifying the plausible risks or failure modes affecting the quality attributes of the drug product. As per the preliminary studies, viz solubility and phase titration studies, and factor screening studies, Maisine (i.e., lipid), Tween 80 (emulgent), Transcutol HP (i.e., cosolvent) were selected as the critical material attributes (CMAs) of the liquid SNEOFs (L-SNEOFs). D-optimal mixture design was employed for the optimization of aforesaid CMAs and evaluated for in vitro dissolution, globule size, ex vivo permeation studies as the critical quality attributes (CQAs). Optimal composition of CMAs, was embarked through numerical optimization and desirability function, exhibited excellent permeation and drug release characteristics besides possessing globule size in nano range, i.e., 53.16nm. Further to increase the stability and drug loading, the OPT-L-SNEOFs were then adsorbed onto the porous carrier, i.e., Aeroperl, to prepare the OPT-SNEOF tablets which were finally compressed into the tablet employing MCC as the filler. The performance evaluation through in situ SPIP studies ascribed the significant enhancement in absorptivity parameters of both the SNEOFs vis-à-vis the pure drug. Also, chylomicron flow block SPIP studies revealed lymphatic uptake of lopinavir from the SNEOFs. Overall, in vivo pharmacokinetic studies in rats revealed significant improvement in the rate and extent of oral bioavailability of the SNEOFs compared to the pure drug. These studies

  19. The influence of a six-week, high-intensity games intervention on the pulmonary oxygen uptake kinetics in prepubertal obese and normal-weight children.

    PubMed

    McNarry, Melitta A; Lambrick, Danielle; Westrupp, Nicole; Faulkner, James

    2015-10-01

    The pulmonary oxygen uptake response is deleteriously influenced by obesity in prepubertal children, as evidenced by a slower phase II response. To date, no studies have investigated the ability of an exercise intervention to ameliorate this. The objective of the study was to investigate the influence of a 6-week, high-intensity, games-orientated intervention on the oxygen uptake kinetic response of prepubertal obese and normal-weight children during heavy-intensity exercise. Thirteen normal-weight and 15 obese children participated in a twice-weekly exercise intervention involving repeated bouts of 6-min high-intensity, games-orientated exercises followed by 2 min of recovery. Sixteen normal-weight and 11 obese children served as a control group. At baseline and post-intervention, each participant completed a graded-exercise test to volitional exhaustion and constant work-rate, heavy-intensity exercise. Post-intervention, obese children demonstrated a reduced phase II τ (pre-intervention: 30 ± 8 cf. post-intervention: 24 ± 7 s), mean response time (pre-intervention: 50 ± 10 cf. post-intervention: 38 ± 9 s) and phase II amplitude (pre-intervention: 1.51 ± 0.30 cf. post-intervention: 1.34 ± 0.27 L·min(-1)). No changes were evident in the normal-weight children. In conclusion, the present findings demonstrate that a 6-week, high-intensity intervention can have a significant positive impact on the dynamic oxygen uptake response of obese prepubertal children. PMID:26352388

  20. Molecular dynamics simulations reveal highly permeable oxygen exit channels shared with water uptake channels in photosystem II.

    PubMed

    Vassiliev, Serguei; Zaraiskaya, Tatiana; Bruce, Doug

    2013-10-01

    Photosystem II (PSII) catalyzes the oxidation of water in the conversion of light energy into chemical energy in photosynthesis. Water delivery and oxygen removal from the oxygen evolving complex (OEC), buried deep within PSII, are critical requirements to facilitate the reaction and minimize reactive oxygen damage. It has often been assumed that water and oxygen travel through separate channels within PSII, as demonstrated in cytochrome c oxidase. This study describes all-atom molecular dynamics simulations of PSII designed to investigate channels by fully characterizing the distribution and permeation of both water and oxygen. Interestingly, most channels found in PSII were permeable to both oxygen and water, however individual channels exhibited different energetic barriers for the two solutes. Several routes for oxygen diffusion within PSII with low energy permeation barriers were found, ensuring its fast removal from the OEC. In contrast, all routes for water showed significant energy barriers, corresponding to a much slower permeation rate for water through PSII. Two major factors were responsible for this selectivity: (1) hydrogen bonds between water and channel amino acids, and (2) steric restraints. Our results reveal the presence of a shared network of channels in PSII optimized to both facilitate the quick removal of oxygen and effectively restrict the water supply to the OEC to help stabilize and protect it from small water soluble inhibitors. PMID:23816955

  1. Fish embryos on land: terrestrial embryo deposition lowers oxygen uptake without altering growth or survival in the amphibious fish Kryptolebias marmoratus.

    PubMed

    Wells, Michael W; Turko, Andy J; Wright, Patricia A

    2015-10-01

    Few teleost fishes incubate embryos out of water, but the oxygen-rich terrestrial environment could provide advantages for early growth and development. We tested the hypothesis that embryonic oxygen uptake is limited in aquatic environments relative to air using the self-fertilizing amphibious mangrove rivulus, Kryptolebias marmoratus, which typically inhabits hypoxic, water-filled crab burrows. We found that adult mangrove rivulus released twice as many embryos in terrestrial versus aquatic environments and that air-reared embryos had accelerated developmental rates. Surprisingly, air-reared embryos consumed 44% less oxygen and possessed larger yolk reserves, but attained the same mass, length and chorion thickness. Water-reared embryos moved their opercula ∼2.5 more times per minute compared with air-reared embryos at 7 days post-release, which probably contributed to the higher rates of oxygen uptake and yolk utilization we observed. Genetically identical air- and water-reared embryos from the same parent were raised to maturity, but the embryonic environment did not affect growth, reproduction or emersion ability in adults. Therefore, although aspects of early development were plastic, these early differences were not sustained into adulthood. Kryptolebias marmoratus embryos hatched out of water when exposed to aerial hypoxia. We conclude that exposure to a terrestrial environment reduces the energetic costs of development partly by reducing the necessity of embryonic movements to dispel stagnant boundary layers. Terrestrial incubation of young would be especially beneficial to amphibious fishes that occupy aquatic habitats of poor water quality, assuming low terrestrial predation and desiccation risks. PMID:26491194

  2. Visualization of lipid metabolism in the larval zebrafish intestine reveals a relationship between NPC1L1 mediated cholesterol uptake and dietary fatty acids

    PubMed Central

    Walters, James W.; Anderson, Jennifer L.; Bittman, Robert; Pack, Michael; Farber, Steven A.

    2012-01-01

    SUMMARY The small intestine is the primary site of dietary lipid absorption in mammals. The balance of nutrients, microorganisms, bile, and mucus that determine intestinal luminal environment cannot be recapitulated ex vivo, thus complicating studies of lipid absorption. We show that fluorescently labeled lipids can be used to visualize and study lipid absorption in live zebrafish larvae. We demonstrate that the addition of BODIPY-fatty acid to a diet high in atherogenic lipids enables imaging of enterocyte lipid droplet dynamics in real time. We find that a lipid-rich meal promotes BODIPY-cholesterol absorption into an endosomal compartment distinguishable from lipid droplets. We also show that dietary fatty acids promote intestinal cholesterol absorption by rapid relocalization of NPC1L1 to intestinal brush border. These data illustrate the power of the zebrafish system to address longstanding questions in vertebrate digestive physiology. PMID:22749558

  3. Diminishing impairments in glucose uptake, mitochondrial content, and ADP-stimulated oxygen flux by mesenchymal stem cell therapy in the infarcted heart.

    PubMed

    Hughey, Curtis C; James, Freyja D; Ma, Lianli; Bracy, Deanna P; Wang, Zhizhang; Wasserman, David H; Rottman, Jeffrey N; Shearer, Jane

    2014-01-01

    A constant provision of ATP is of necessity for cardiac contraction. As the heart progresses toward failure following a myocardial infarction (MI), it undergoes metabolic alterations that have the potential to compromise the ability to meet energetic demands. This study evaluated the efficacy of mesenchymal stem cell (MSC) transplantation into the infarcted heart to minimize impairments in the metabolic processes that contribute to energy provision. Seven and twenty-eight days following the MI and MSC transplantation, MSC administration minimized cardiac systolic dysfunction. Hyperinsulinemic-euglycemic clamps, coupled with 2-[(14)C]deoxyglucose administration, were employed to assess systemic insulin sensitivity and tissue-specific, insulin-mediated glucose uptake 36 days following the MI in the conscious, unrestrained, C57BL/6 mouse. The improved systolic performance in MSC-treated mice was associated with a preservation of in vivo insulin-stimulated cardiac glucose uptake. Conserved glucose uptake in the heart was linked to the ability of the MSC treatment to diminish the decline in insulin signaling as assessed by Akt phosphorylation. The MSC treatment also sustained mitochondrial content, ADP-stimulated oxygen flux, and mitochondrial oxidative phosphorylation efficiency in the heart. Maintenance of mitochondrial function and density was accompanied by preserved peroxisome proliferator-activated receptor-γ coactivator-1α, a master regulator of mitochondrial biogenesis. These studies provide insight into mechanisms of action that lead to an enhanced energetic state in the infarcted heart following MSC transplantation that may assist in energy provision and dampen cardiac dysfunction. PMID:24196528

  4. Diminishing impairments in glucose uptake, mitochondrial content, and ADP-stimulated oxygen flux by mesenchymal stem cell therapy in the infarcted heart

    PubMed Central

    James, Freyja D.; Ma, Lianli; Bracy, Deanna P.; Wang, Zhizhang; Wasserman, David H.; Rottman, Jeffrey N.; Shearer, Jane

    2013-01-01

    A constant provision of ATP is of necessity for cardiac contraction. As the heart progresses toward failure following a myocardial infarction (MI), it undergoes metabolic alterations that have the potential to compromise the ability to meet energetic demands. This study evaluated the efficacy of mesenchymal stem cell (MSC) transplantation into the infarcted heart to minimize impairments in the metabolic processes that contribute to energy provision. Seven and twenty-eight days following the MI and MSC transplantation, MSC administration minimized cardiac systolic dysfunction. Hyperinsulinemic-euglycemic clamps, coupled with 2-[14C]deoxyglucose administration, were employed to assess systemic insulin sensitivity and tissue-specific, insulin-mediated glucose uptake 36 days following the MI in the conscious, unrestrained, C57BL/6 mouse. The improved systolic performance in MSC-treated mice was associated with a preservation of in vivo insulin-stimulated cardiac glucose uptake. Conserved glucose uptake in the heart was linked to the ability of the MSC treatment to diminish the decline in insulin signaling as assessed by Akt phosphorylation. The MSC treatment also sustained mitochondrial content, ADP-stimulated oxygen flux, and mitochondrial oxidative phosphorylation efficiency in the heart. Maintenance of mitochondrial function and density was accompanied by preserved peroxisome proliferator-activated receptor-γ coactivator-1α, a master regulator of mitochondrial biogenesis. These studies provide insight into mechanisms of action that lead to an enhanced energetic state in the infarcted heart following MSC transplantation that may assist in energy provision and dampen cardiac dysfunction. PMID:24196528

  5. Ozone uptake on glassy, semi-solid and liquid organic matter and the role of reactive oxygen intermediates in atmospheric aerosol chemistry.

    PubMed

    Berkemeier, Thomas; Steimer, Sarah S; Krieger, Ulrich K; Peter, Thomas; Pöschl, Ulrich; Ammann, Markus; Shiraiwa, Manabu

    2016-05-14

    Heterogeneous and multiphase reactions of ozone are important pathways for chemical ageing of atmospheric organic aerosols. To demonstrate and quantify how moisture-induced phase changes can affect the gas uptake and chemical transformation of organic matter, we apply a kinetic multi-layer model to a comprehensive experimental data set of ozone uptake by shikimic acid. The bulk diffusion coefficients were determined to be 10(-12) cm(2) s(-1) for ozone and 10(-20) cm(2) s(-1) for shikimic acid under dry conditions, increasing by several orders of magnitude with increasing relative humidity (RH) due to phase changes from amorphous solid over semisolid to liquid. Consequently, the reactive uptake of ozone progresses through different kinetic regimes characterised by specific limiting processes and parameters. At high RH, ozone uptake is driven by reaction throughout the particle bulk; at low RH it is restricted to reaction near the particle surface and kinetically limited by slow diffusion and replenishment of unreacted organic molecules. Our results suggest that the chemical reaction mechanism involves long-lived reactive oxygen intermediates, likely primary ozonides or O atoms, which may provide a pathway for self-reaction and catalytic destruction of ozone at the surface. Slow diffusion and ozone destruction can effectively shield reactive organic molecules in the particle bulk from degradation. We discuss the potential non-orthogonality of kinetic parameters, and show how this problem can be solved by using comprehensive experimental data sets to constrain the kinetic model, providing mechanistic insights into the coupling of transport, phase changes, and chemical reactions of multiple species in complex systems. PMID:27095585

  6. Arm Crank and Wheelchair Ergometry Produce Similar Peak Oxygen Uptake but Different Work Economy Values in Individuals with Spinal Cord Injury

    PubMed Central

    Helgerud, Jan

    2016-01-01

    Objective. To study whether values for peak oxygen uptake (VO2peak) and work economy (WE) at a standardized workload are different when tested by arm crank ergometry (ACE) and wheelchair ergometry (WCE). Methods. Twelve paraplegic men with spinal cord injury (SCI) in stable neurological condition participated in this cross-sectional repeated-measures study. We determined VO2peak and peak power output (POpeak) values during ACE and WCE in a work-matched protocol. Work economy was tested at a standardized workload of 30 Watts (W) for both ACE and WCE. Results. There were no significant differences in VO2peak (mL·kg−1·min−1) between ACE (27.3 ± 3.2) and WCE (27.4 ± 3.8) trials, and a Bland-Altman plot shows that findings are within 95% level of agreement. WE or oxygen consumption at 30 W (VO2-30W) was significantly lower during WCE compared to ACE (P < 0.039). Mean (95% CI) POpeak (W) were 130 (111–138) and 100 (83–110) during ACE and WCE, respectively. Conclusion. The findings in the present study support the use of both ACE and WCE for testing peak oxygen uptake. However, WE differed between the two test modalities, meaning that less total energy is used to perform external work of 30 W during wheelchair exercise when using this WCE (VP100 Handisport ergometer). Clinical Trials Protocol Record is NCT00987155/4.2007.2271. PMID:27144169

  7. Arm Crank and Wheelchair Ergometry Produce Similar Peak Oxygen Uptake but Different Work Economy Values in Individuals with Spinal Cord Injury.

    PubMed

    Tørhaug, Tom; Brurok, Berit; Hoff, Jan; Helgerud, Jan; Leivseth, Gunnar

    2016-01-01

    Objective. To study whether values for peak oxygen uptake (VO2peak) and work economy (WE) at a standardized workload are different when tested by arm crank ergometry (ACE) and wheelchair ergometry (WCE). Methods. Twelve paraplegic men with spinal cord injury (SCI) in stable neurological condition participated in this cross-sectional repeated-measures study. We determined VO2peak and peak power output (POpeak) values during ACE and WCE in a work-matched protocol. Work economy was tested at a standardized workload of 30 Watts (W) for both ACE and WCE. Results. There were no significant differences in VO2peak (mL·kg(-1)·min(-1)) between ACE (27.3 ± 3.2) and WCE (27.4 ± 3.8) trials, and a Bland-Altman plot shows that findings are within 95% level of agreement. WE or oxygen consumption at 30 W (VO2-30W) was significantly lower during WCE compared to ACE (P < 0.039). Mean (95% CI) POpeak (W) were 130 (111-138) and 100 (83-110) during ACE and WCE, respectively. Conclusion. The findings in the present study support the use of both ACE and WCE for testing peak oxygen uptake. However, WE differed between the two test modalities, meaning that less total energy is used to perform external work of 30 W during wheelchair exercise when using this WCE (VP100 Handisport ergometer). Clinical Trials Protocol Record is NCT00987155/4.2007.2271. PMID:27144169

  8. GLP-2-MEDIATED UP-REGULATION OF INTESTINAL BLOOD FLOW AND GLUCOSE UPTAKE IS NITRIC OXIDE-DEPENDENT IN TPN-FED PIGLETS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    BACKGROUND & AIMS: Our aim was to determine whether the intestinotrophic effects of GLP-2 are mediated by acute up-regulation of intestinal substrate utilization in TPN-fed piglets. METHODS: Twenty-four 12-day-old pigs, fitted with a portal flow probe and carotid, jugular and portal catheters, were ...

  9. Effect of training on maximal oxygen uptake and aerobic capacity of locomotory muscles in tufted ducks, Aythya fuligula.

    PubMed

    Butler, P J; Turner, D L

    1988-07-01

    1. The effects of artificial swim training on maximal oxygen consumption and heart rate, as well as on the capillarity and oxidative capacity of locomotory muscles, have been studied in the tufted duck, Aythya fuligula. 2. The artificial training programme resulted in a 27% increase in maximal oxygen consumption, mainly as a result of an increase in muscle capillarity (20% increase in capillary/fibre ratio). In addition, activity of an oxidative enzyme, citrate synthase, increased (by 42%) and there was a significant transformation of fibre types in the lateral gastrocnemius muscle. 3. Altering the duration and nature of the training stimulus, for example flying and diving, can bring about different degrees of muscular adaptation, particularly in oxidative capacity. PMID:3171990

  10. Effect of training on maximal oxygen uptake and aerobic capacity of locomotory muscles in tufted ducks, Aythya fuligula.

    PubMed Central

    Butler, P J; Turner, D L

    1988-01-01

    1. The effects of artificial swim training on maximal oxygen consumption and heart rate, as well as on the capillarity and oxidative capacity of locomotory muscles, have been studied in the tufted duck, Aythya fuligula. 2. The artificial training programme resulted in a 27% increase in maximal oxygen consumption, mainly as a result of an increase in muscle capillarity (20% increase in capillary/fibre ratio). In addition, activity of an oxidative enzyme, citrate synthase, increased (by 42%) and there was a significant transformation of fibre types in the lateral gastrocnemius muscle. 3. Altering the duration and nature of the training stimulus, for example flying and diving, can bring about different degrees of muscular adaptation, particularly in oxidative capacity. PMID:3171990

  11. Evaluating CMIP5 ocean biogeochemistry and Southern Ocean carbon uptake using atmospheric potential oxygen: Present-day performance and future projection

    NASA Astrophysics Data System (ADS)

    Nevison, C. D.; Manizza, M.; Keeling, R. F.; Stephens, B. B.; Bent, J. D.; Dunne, J.; Ilyina, T.; Long, M.; Resplandy, L.; Tjiputra, J.; Yukimoto, S.

    2016-03-01

    Observed seasonal cycles in atmospheric potential oxygen (APO ~ O2 + 1.1 CO2) were used to evaluate eight ocean biogeochemistry models from the Coupled Model Intercomparison Project (CMIP5). Model APO seasonal cycles were computed from the CMIP5 air-sea O2 and CO2 fluxes and compared to observations at three Southern Hemisphere monitoring sites. Four of the models captured either the observed APO seasonal amplitude or phasing relatively well, while the other four did not. Many models had an unrealistic seasonal phasing or amplitude of the CO2 flux, which in turn influenced APO. By 2100 under RCP8.5, the models projected little change in the O2 component of APO but large changes in the seasonality of the CO2 component associated with ocean acidification. The models with poorer performance on present-day APO tended to project larger net carbon uptake in the Southern Ocean, both today and in 2100.

  12. CKM Gene G (Ncoi-) Allele Has a Positive Effect on Maximal Oxygen Uptake in Caucasian Women Practicing Sports Requiring Aerobic and Anaerobic Exercise Metabolism

    PubMed Central

    Gronek, Piotr; Holdys, Joanna; Kryściak, Jakub; Stanisławski, Daniel

    2013-01-01

    The search for genes with a positive influence on physical fitness is a difficult process. Physical fitness is a trait determined by multiple genes, and its genetic basis is then modified by numerous environmental factors. The present study examines the effects of the polymorphism of creatine kinase (CKM) gene on VO2max – a physiological index of aerobic capacity of high heritability. The study sample consisted of 154 men and 85 women, who were students of the University School of Physical Education in Poznań and athletes practicing various sports, including members of the Polish national team. The study revealed a positive effect of a rare G (NcoI−) allele of the CKM gene on maximal oxygen uptake in Caucasian women practicing sports requiring aerobic and anaerobic exercise metabolism. Also a tendency was noted in individuals with NcoI−/− (GG) and NcoI−/+ (GA) genotypes to reach higher VO2max levels. PMID:24511349

  13. Respiratory oxygen uptake is not decreased by an instantaneous elevation of [CO2], but is increased with long-term growth in the field at elevated [CO2].

    PubMed

    Davey, Phillip A; Hunt, Stephen; Hymus, Graham J; DeLucia, Evan H; Drake, Bert G; Karnosky, David F; Long, Stephen P

    2004-01-01

    Averaged across many previous investigations, doubling the CO2 concentration ([CO2]) has frequently been reported to cause an instantaneous reduction of leaf dark respiration measured as CO2 efflux. No known mechanism accounts for this effect, and four recent studies have shown that the measurement of respiratory CO2 efflux is prone to experimental artifacts that could account for the reported response. Here, these artifacts are avoided by use of a high-resolution dual channel oxygen analyzer within an open gas exchange system to measure respiratory O2 uptake in normal air. Leaf O2 uptake was determined in response to instantaneous elevation of [CO2] in nine contrasting species and to long-term elevation in seven species from four field experiments. Over six hundred separate measurements of respiration failed to reveal any decrease in respiratory O2 uptake with an instantaneous increase in [CO2]. Respiration was found insensitive not only to doubling [CO2], but also to a 5-fold increase and to decrease to zero. Using a wide range of species and conditions, we confirm earlier reports that inhibition of respiration by instantaneous elevation of [CO2] is likely an experimental artifact. Instead of the expected decrease in respiration per unit leaf area in response to long-term growth in the field at elevated [CO2], there was a significant increase of 11% and 7% on an area and mass basis, respectively, averaged across all experiments. The findings suggest that leaf dark respiration will increase not decrease as atmospheric [CO2] rises. PMID:14701915

  14. Oxygen Uptake Efficiency Slope and Breathing Reserve, Not Anaerobic Threshold, Discriminate Between Patients With Cardiovascular Disease Over Chronic Obstructive Pulmonary Disease

    PubMed Central

    Barron, Anthony; Francis, Darrel P.; Mayet, Jamil; Ewert, Ralf; Obst, Anne; Mason, Mark; Elkin, Sarah; Hughes, Alun D.; Wensel, Roland

    2016-01-01

    Objectives The study sought to compare the relative discrimination of various cardiopulmonary exercise testing (CPX) variables between cardiac and respiratory disease. Background CPX testing is used in many cardiorespiratory diseases. However, discrimination of cardiac and respiratory dysfunction can be problematic. Anaerobic threshold (AT) and oxygen-uptake to work-rate relationship (VO2/WR slope) have been proposed as diagnostic of cardiac dysfunction, but multiple variables have not been compared. Methods A total of 73 patients with chronic obstructive pulmonary disease (COPD) (n = 25), heart failure with reduced ejection fraction (HFrEF) (n = 40), or combined COPD and HFrEF (n = 8) were recruited and underwent CPX testing on a bicycle ergometer. Following a familiarization test, each patient underwent a personalized second test aiming for maximal exercise after ∼10 min. Measurements from this test were used to calculate area under the receiver-operator characteristic curve (AUC). Results Peak VO2 was similar between the 2 principal groups (COPD 17.1 ± 4.6 ml/min/kg; HFrEF 16.4 ± 3.6 ml/min/kg). Breathing reserve (AUC: 0.91) and percent predicted oxygen uptake efficiency slope (OUES) (AUC: 0.87) had the greatest ability to discriminate between COPD and HFrEF. VO2/WR slope performed significantly worse (AUC: 0.68). VO2 at the AT did not discriminate (AUC for AT as percent predicted peak VO2: 0.56). OUES and breathing reserve remained strong discriminators when compared with an external cohort of healthy matched controls, and were comparable to B-type natriuretic peptide. Conclusions Breathing reserve and OUES discriminate heart failure from COPD. Despite it being considered an important determinant of cardiac dysfunction, the AT could not discriminate these typical clinical populations while the VO2/WR slope showed poor to moderate discriminant ability. (Identifying an Ideal Cardiopulmonary Exercise Test Parameter [PVA]; NCT01162083) PMID:26874378

  15. Roles of Oxygen and the Intestinal Microflora in the Metabolism of Lignin-Derived Phenylpropanoids and Other Monoaromatic Compounds by Termites

    PubMed Central

    Brune, A.; Miambi, E.; Breznak, J. A.

    1995-01-01

    10(sup3) bacteria per gut). Neither inclusion of potential cosubstrates (H(inf2), pyruvate, lactate) nor inclusion of hydrogenotrophic partner organisms resulted in anoxic ring cleavage in most-probable-number tubes prepared with gut homogenates of either termite. The oxygen dependence of aromatic ring cleavage by the termite gut microbiota is consistent with the presence, and uptake by microbes, of O(inf2) in the peripheral region of otherwise anoxic gut lumina (as reported in the accompanying paper [A. Brune, D. Emerson, and J. A. Breznak, Appl. Environ. Microbiol. 61:2681-2687, 1995]). Taken together, our results indicate that microbial degradation of plant aromatic compounds can occur in termite guts and may contribute to the carbon and energy requirement of the host. PMID:16535077

  16. Gas analyzer's drift leads to systematic error in maximal oxygen uptake and maximal respiratory exchange ratio determination

    PubMed Central

    Garcia-Tabar, Ibai; Eclache, Jean P.; Aramendi, José F.; Gorostiaga, Esteban M.

    2015-01-01

    The aim was to examine the drift in the measurements of fractional concentration of oxygen (FO2) and carbon dioxide (FCO2) of a Nafion-using metabolic cart during incremental maximal exercise in 18 young and 12 elderly males, and to propose a way in which the drift can be corrected. The drift was verified by comparing the pre-test calibration values with the immediate post-test verification values of the calibration gases. The system demonstrated an average downscale drift (P < 0.001) in FO2 and FCO2 of −0.18% and −0.05%, respectively. Compared with measured values, corrected average maximal oxygen uptakevalues were 5–6% lower (P < 0.001) whereas corrected maximal respiratory exchange ratio values were 8–9% higher (P < 0.001). The drift was not due to an electronic instability in the analyzers because it was reverted after 20 min of recovery from the end of the exercise. The drift may be related to an incomplete removal of water vapor from the expired gas during transit through the Nafion conducting tube. These data demonstrate the importance of checking FO2 and FCO2 values by regular pre-test calibrations and post-test verifications, and also the importance of correcting a possible shift immediately after exercise. PMID:26578980

  17. Slowed oxygen uptake kinetics in hypoxia correlate with the transient peak and reduced spatial distribution of absolute skeletal muscle deoxygenation.

    PubMed

    Bowen, T Scott; Rossiter, Harry B; Benson, Alan P; Amano, Tatsuro; Kondo, Narihiko; Kowalchuk, John M; Koga, Shunsaku

    2013-11-01

    It remains unclear whether an overshoot in skeletal muscle deoxygenation (HHb; reflecting a microvascular kinetic mismatch of O2 delivery to consumption) contributes to the slowed adjustment of oxidative energy provision at the onset of exercise. We progressively reduced the fractional inspired O2 concentration (F(I,O2)) to investigate the relationship between slowed pulmonary O2 uptake (V(O2)) kinetics and the dynamics and spatial distribution of absolute[HHb]. Seven healthy men performed 8 min cycling transitions during normoxia (F(I,O2) = 0.21),moderate hypoxia (F(I,O2) = 0.16) and severe hypoxia (F(I,O2)= 0.12). V(O2) uptake was measured using a flowmeter and gas analyser system. Absolute [HHb] was quantified by multichannel,time-resolved near-infrared spectroscopy from the rectus femoris and vastus lateralis (proximal and distal regions), and corrected for adipose tissue thickness. The phase II V(O2) time constant was slowed (P <0.05) as F(I,O2) decreased (normoxia, 17 ± 3 s;moderate hypoxia, 22 ± 4 s; and severe hypoxia, 29 ± 9 s). The [HHb] overshoot was unaffected by hypoxia, but the transient peak [HHb] increased with the reduction in F(I,O2) (P <0.05). Slowed V(O2) kinetics in hypoxia were positively correlated with increased peak [HHb] in the transient (r(2) = 0.45; P <0.05), but poorly related to the [HHb] overshoot. A reduction of spatial heterogeneity in peak [HHb]was inversely correlated with slowed V(O2) kinetics (r(2) = 0.49; P <0.05). These data suggest that aerobic energy provision at the onset of exercise may be limited by the following factors: (i) the absolute ratio (i.e. peak [HHb]) rather than the kinetic ratio (i.e. [HHb] overshoot) of microvascular O2 delivery to consumption; and (ii) a reduced spatial distribution in the ratio of microvascular O2 delivery to consumption across the muscle. PMID:23851917

  18. Oxygen-Dependent Transcriptional Regulator Hap1p Limits Glucose Uptake by Repressing the Expression of the Major Glucose Transporter Gene RAG1 in Kluyveromyces lactis▿

    PubMed Central

    Bao, Wei-Guo; Guiard, Bernard; Fang, Zi-An; Donnini, Claudia; Gervais, Michel; Passos, Flavia M. Lopes; Ferrero, Iliana; Fukuhara, Hiroshi; Bolotin-Fukuhara, Monique

    2008-01-01

    The HAP1 (CYP1) gene product of Saccharomyces cerevisiae is known to regulate the transcription of many genes in response to oxygen availability. This response varies according to yeast species, probably reflecting the specific nature of their oxidative metabolism. It is suspected that a difference in the interaction of Hap1p with its target genes may explain some of the species-related variation in oxygen responses. As opposed to the fermentative S. cerevisiae, Kluyveromyces lactis is an aerobic yeast species which shows different oxygen responses. We examined the role of the HAP1-equivalent gene (KlHAP1) in K. lactis. KlHap1p showed a number of sequence features and some gene targets (such as KlCYC1) in common with its S. cerevisiae counterpart, and KlHAP1 was capable of complementing the hap1 mutation. However, the KlHAP1 disruptant showed temperature-sensitive growth on glucose, especially at low glucose concentrations. At normal temperature, 28°C, the mutant grew well, the colony size being even greater than that of the wild type. The most striking observation was that KlHap1p repressed the expression of the major glucose transporter gene RAG1 and reduced the glucose uptake rate. This suggested an involvement of KlHap1p in the regulation of glycolytic flux through the glucose transport system. The ΔKlhap1 mutant showed an increased ability to produce ethanol during aerobic growth, indicating a possible transformation of its physiological property to Crabtree positivity or partial Crabtree positivity. Dual roles of KlHap1p in activating respiration and repressing fermentation may be seen as a basis of the Crabtree-negative physiology of K. lactis. PMID:18806211

  19. Goblet Cells and Mucus Types in the Digestive Intestine and Respiratory Intestine in Bronze Corydoras (Callichthyidae: Teleostei).

    PubMed

    Leknes, I L

    2015-10-01

    The structure and histochemical properties of the intestine in bronze corydoras (Corydoras aeneus), a stomach-containing teleost, are described, with emphasis on goblet cells and mucin types. The proximal intestine displayed a normal structure for teleosts, whereas the distal intestine was wide, translucent, thin-walled, richly vascularized and constantly filled with air, suggesting an important respiratory role. Goblet cells were common throughout the entire intestine and displayed a variable, but mainly faint metachromatic colour after toluidine blue. They were moderately coloured by alcian blue at both pH 2.5 and 0.2 and displayed no colour after periodic acid followed by Schiff's solution (PAS), but a distinct purple-brown colour after high iron diamine followed by alcian blue (pH 2.5). Together, these results suggest that the mucin in the intestine goblet cells consists mainly of sulphated proteoglycans. Further, the results from the present lectin and neuraminidase tests suggest that these mucins contain much N-acetylglucoseamines and some N-acetylgalactosamines and sialic acid, but seem to lack glucose and mannose. They also contain some galactose-N-acetylgalactosamines sequences, normally hidden by sialic acid. The distinct brush border and mucus layer on the epithelial cells in the respiratory intestine may indicate some digestive roles, such as absorption of water, ions and simple carbohydrates. As sulphated proteoglycans are tough and attract much water, this mucus may play important roles in the protection against mechanical and chemical damages and in the defence against micro-organisms throughout the entire intestine, but in the respiratory intestine it may impede significantly the oxygen uptake. However, as this part of the intestine usually contains no digesta, but is completely filled with air, frequently renewed by dry air from the atmosphere, and the main function of the mucus may be to protect the respiratory epithelium against a destroying and

  20. The leveling-off of oxygen uptake is related to blood lactate accumulation. Retrospective study of 94 elite rowers.

    PubMed

    Lacour, Jean-René; Messonnier, Laurent; Bourdin, Muriel

    2007-09-01

    To assess whether the ability to demonstrate a plateau in oxygen consumption VO2 could be related to adaptation to exercise, the data obtained over a period of 10 years on 94 elite oarsmen who had participated in annual testing were re-evaluated. The test consisted in an incremental step protocol until volitional exhaustion. VO2, heart rate (HR), blood lactate ([La]b) and respiratory exchange ratio (RER) were measured at each step. The maximal oxygen consumption (VO2max), the power corresponding to VO2maxPamax and the maximal power achieved (Ppeak) were recorded. Thirty-eight oarsmen achieved a VO2 plateau and were designated as Pla; 56 did not and were designed as N-Pla. The Pla and N-Pla VO2max, Pamax and maximal HR values were similar. In comparison with N-Pla, the Pla group displayed a rightward shift of the [La]b versus power curve, accounted for by both the increased percentage of VO2max corresponding to 4 mmol l(-1) and the decreased value of [La]b corresponding to Pamax (P<0.05). Pla oarsmen attained a higher Ppeak expressed as % of Pamax (P<0.05) and also showed better ergometer performance (P<0.05). In a sub-group of 53 oarsmen constituted on the basis of Pamax values close to 400 W, for a given power output, the Pla subjects had significantly lower HR, RER, and [La]b values at each sub-maximal stage of the test. These results suggest that achieving a [Formula: see text] plateau during completion of an incremental step protocol accounts for greater muscle ability to maintain homeostasis during exercise. These differences give the oarsmen an advantage in rowing competitions. PMID:17564723

  1. Effects of bile and bile salts on growth and membrane lipid uptake by Giardia lamblia. Possible implications for pathogenesis of intestinal disease.

    PubMed Central

    Farthing, M J; Keusch, G T; Carey, M C

    1985-01-01

    We have shown previously that ox and pig bile accelerate in vitro growth of Giardia lamblia. We have now investigated the possible mechanisms by which mammalian biles promote parasite growth. Growth effects of (a) ox, pig, guinea pig, and human biles, (b) pure bile salts, and (c) egg and soybean lecithins were studied in the presence of a lecithin-containing growth medium. Individually, dilute native bile and pure sodium taurocholate (TC), glycocholate (GC), and taurodeoxycholate (TDC) promoted parasite growth; growth was most marked with biles of high phospholipid content, with biles enriched in more hydrophobic bile salts (ox approximately equal to human greater than pig greater than guinea pig) and with micellar concentrations of GC and submicellar concentrations of TC and TDC. By measuring uptake of radiolabeled biliary lipids from bile and bile salt-supplemented growth medium, we showed that the parasite consumed bile lipids, with the rank order lecithin greater than bile salts. Apparent net uptake of cholesterol was considered to be due to exchange, since net loss of cholesterol from the growth medium was not detected. Although bile and bile salt-stimulated parasite growth was associated with enhanced lecithin uptake, reduction in generation time was observed at low bile and bile salt concentrations when lecithin uptake was similar to bile free controls. Thus, bile salts may stimulate Giardia growth initially by a mechanism independent of enhanced membrane phospholipid uptake. However, since Giardia has no capacity to synthesize membrane lipid, biliary lecithin may be a major source of phospholipid for growth of this parasite. PMID:4056050

  2. Oxygen uptake on-kinetics in dog gastrocnemius in situ following activation of pyruvate dehydrogenase by dichloroacetate.

    PubMed

    Grassi, Bruno; Hogan, Michael C; Greenhaff, Paul L; Hamann, Jason J; Kelley, Kevin M; Aschenbach, William G; Constantin-Teodosiu, Dumitru; Gladden, L Bruce

    2002-01-01

    The aim of the present study was to determine whether the activation of the pyruvate dehydrogenase complex (PDC) by dichloroacetate (DCA) is associated with faster O(2) uptake (V(O2)) on-kinetics. V(O2) on-kinetics was determined in isolated canine gastrocnemius muscles in situ (n = 6) during the transition from rest to 4 min of electrically stimulated isometric tetanic contractions, corresponding to approximately 60-70 % of peak V(O2). Two conditions were compared: (1) control (saline infusion, C); and (2) DCA infusion (300 mg (kg body mass)(-1), 45 min before contraction). Muscle blood flow (Q) was measured continuously in the popliteal vein; arterial and popliteal vein O(2) contents were measured at rest and at 5-7 s intervals during the transition. Muscle V(O2) was calculated as Q multiplied by the arteriovenous O(2) content difference. Muscle biopsies were taken before and at the end of contraction for determination of muscle metabolite concentrations. DCA activated PDC at rest, as shown by the 9-fold higher acetylcarnitine concentration in DCA (vs. C; P < 0.0001). Phosphocreatine degradation and muscle lactate accumulation were not significantly different between C and DCA. DCA was associated with significantly less muscle fatigue. Resting and steady-state V(O2) values during contraction were not significantly different between C and DCA. The time to reach 63 % of the V(O2) difference between the resting baseline and the steady-state V(O2) values during contraction was 22.3 +/- 0.5 s in C and 24.5 +/- 1.4 s in DCA (n.s.). In this experimental model, activation of PDC by DCA resulted in a stockpiling of acetyl groups at rest and less muscle fatigue, but it did not affect 'anaerobic' energy provision and V(O2) on-kinetics. PMID:11773328

  3. Effects of nitric oxide synthase inhibition by l-NAME on oxygen uptake kinetics in isolated canine muscle in situ

    PubMed Central

    Grassi, Bruno; Hogan, Michael C; Kelley, Kevin M; Howlett, Richard A; Gladden, L Bruce

    2005-01-01

    Nitric oxide (NO) has an inhibitory action on O2 uptake (V˙O2) at the level of the mitochondrial respiratory chain. The aim of this study was to evaluate the effects of NO synthase (NOS) inhibition on muscle V˙O2 kinetics. Isolated canine gastrocnemius muscles in situ (n= 6) were studied during transitions from rest to 4-min of electrically stimulated contractions corresponding to ∼60% of the muscle peak V˙O2. Two conditions were compared: (i) Control (CTRL) and (ii) l-NAME, in which the NOS inhibitor l-NAME (20 mg kg−1) was administered. In both conditions the muscle was pump-perfused with constantly elevated blood flow (Q˙), at a level measured during a preliminary contraction trial with spontaneous self-perfused Q˙. A vasodilatory drug was also infused. Arterial and venous O2 concentrations were determined at rest and at 5–7 s intervals during the transition. V˙O2 was calculated by Fick's principle. Muscle biopsies were obtained at rest and during contractions. Muscle force was measured continuously. Phosphocreatine hydrolysis and the calculated substrate level phosphorylation were slightly (but not significantly) lower in l-NAME than in CTRL. Significantly (P < 0.05) less fatigue was found in l-NAME versus CTRL. The time delay (TDf) and the time constant (τf) of the ‘fundamental’ component of V˙O2 kinetics were not significantly different between CTRL (TDf 7.2 ± 1.2 s; and τf 10.6 ± 1.3, ±s.e.m.) and l-NAME (TDf 9.3 ± 0.6; and τf 10.4 ± 1.0). Contrary to our hypothesis, NOS inhibition did not accelerate muscle V˙O2 kinetics. The down-regulation of mitochondrial respiration by NO does not limit the kinetics of adjustment of oxidative metabolism at exercise onset. PMID:16081490

  4. Intestinal leiomyoma

    MedlinePlus

    Leiomyoma - intestine ... McLaughlin P, Maher MM. The duodenum and small intestine. In: Adam A, Dixon AK, Gillard JH, Schaefer- ... Roline CE, Reardon RF. Disorders of the small intestine. In: Marx JA, Hockberger RS, Walls RM, et ...

  5. Intestinal Cancer

    MedlinePlus

    ... connects your stomach to your large intestine. Intestinal cancer is rare, but eating a high-fat diet ... increase your risk. Possible signs of small intestine cancer include Abdominal pain Weight loss for no reason ...

  6. Contribution of Upper-Body Strength, Body Composition, and Maximal Oxygen Uptake to Predict Double Poling Power and Overall Performance in Female Cross-Country Skiers.

    PubMed

    Østerås, Sindre; Welde, Boye; Danielsen, Jørgen; van den Tillaar, Roland; Ettema, Gertjan; Sandbakk, Øyvind

    2016-09-01

    Østerås, S, Welde, B, Danielsen, J, van den Tillaar, R, Ettema, G, and Sandbakk, Ø. Contribution of upper-body strength, body composition, and maximal oxygen uptake to predict double poling power and overall performance in female cross-country skiers. J Strength Cond Res 30(9): 2557-2564, 2016-Maximal oxygen uptake (V[Combining Dot Above]O2max) is regarded as the most performance-differentiating physiological measure in cross-country (XC) skiing. In addition, upper-body strength and lean mass have been associated with double poling (DP) power in XC skiers. In this study, we tested upper-body maximal strength, lean mass, and V[Combining Dot Above]O2max's contributions to predict DP power production of different durations and the overall XC skiing performance level of elite female XC skiers. Thirteen skiers (V[Combining Dot Above]O2max: 64.9 ± 4.2 ml·kg·min) performed one 30-second and one 3-minute DP performance test using a ski ergometer. The International Ski Federation's (FIS) ranking points determined their overall XC skiing performance. The skiers performed three 1-repetition maximal strength tests in poling-specific exercises that isolated the elbow extension, shoulder extension, and trunk flexion movements. Body composition was determined by a DXA scan, and V[Combining Dot Above]O2max was tested in an incremental running test. Multiple regressions were used to predict power production in the 30-second and 3-minute tests and FIS points. The 2 best predictions of 30-second DP power were lean upper-body mass and maximal upper-body strength (with the 3 strength tests normalized and pooled together as one variable) (R = 0.84 and 0.81, p < 0.001). Along with V[Combining Dot Above]O2max, the same 2 variables were the best predictions of both 3-minute DP power (R = 0.60 and 0.44, p ≤ 0.05) and overall XC skiing performance (R = 0.43 and 0.40, p ≤ 0.05). Although the importance of upper-body strength and lean mass to predict DP power production and the

  7. Skeletal Muscle-Specific Expression of PGC-1α-b, an Exercise-Responsive Isoform, Increases Exercise Capacity and Peak Oxygen Uptake

    PubMed Central

    Tadaishi, Miki; Miura, Shinji; Kai, Yuko; Kano, Yutaka; Oishi, Yuichi; Ezaki, Osamu

    2011-01-01

    Background Maximal oxygen uptake (VO2max) predicts mortality and is associated with endurance performance. Trained subjects have a high VO2max due to a high cardiac output and high metabolic capacity of skeletal muscles. Peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α), a nuclear receptor coactivator, promotes mitochondrial biogenesis, a fiber-type switch to oxidative fibers, and angiogenesis in skeletal muscle. Because exercise training increases PGC-1α in skeletal muscle, PGC-1α-mediated changes may contribute to the improvement of exercise capacity and VO2max. There are three isoforms of PGC-1α mRNA. PGC-1α-b protein, whose amino terminus is different from PGC-1α-a protein, is a predominant PGC-1α isoform in response to exercise. We investigated whether alterations of skeletal muscle metabolism by overexpression of PGC-1α-b in skeletal muscle, but not heart, would increase VO2max and exercise capacity. Methodology/Principal Findings Transgenic mice showed overexpression of PGC-1α-b protein in skeletal muscle but not in heart. Overexpression of PGC-1α-b promoted mitochondrial biogenesis 4-fold, increased the expression of fatty acid transporters, enhanced angiogenesis in skeletal muscle 1.4 to 2.7-fold, and promoted exercise capacity (expressed by maximum speed) by 35% and peak oxygen uptake by 20%. Across a broad range of either the absolute exercise intensity, or the same relative exercise intensities, lipid oxidation was always higher in the transgenic mice than wild-type littermates, suggesting that lipid is the predominant fuel source for exercise in the transgenic mice. However, muscle glycogen usage during exercise was absent in the transgenic mice. Conclusions/Significance Increased mitochondrial biogenesis, capillaries, and fatty acid transporters in skeletal muscles may contribute to improved exercise capacity via an increase in fatty acid utilization. Increases in PGC-1α-b protein or function might be a useful strategy

  8. Photodynamic Inactivation of Candida albicans with Imidazoacridinones: Influence of Irradiance, Photosensitizer Uptake and Reactive Oxygen Species Generation

    PubMed Central

    Taraszkiewicz, Aleksandra; Szewczyk, Grzegorz; Sarna, Tadeusz; Bielawski, Krzysztof P.; Nakonieczna, Joanna

    2015-01-01

    The increasing applicability of antifungal treatments, the limited range of available drug classes and the emergence of drug resistance in Candida spp. suggest the need for new treatment options. To explore the applicability of C. albicans photoinactivation, we examined nine structurally different imidazoacridinone derivatives as photosensitizing agents. The most effective derivatives showed a >104-fold reduction of viable cell numbers. The fungicidal action of the three most active compounds was compared at different radiant powers(3.5 to 63 mW/cm2), and this analysis indicated that 7 mW/cm2 was the most efficient. The intracellular accumulation of these compounds in fungal cells correlated with the fungicidal activity of all 9 derivatives. The lack of effect of verapamil, an inhibitor targeting Candida ABC efflux pumps, suggests that these imidazoacridinones are not substrates for ABC transporters. Thus, unlike azoles, a major class of antifungals used against Candida, ABC transporter-mediated resistance is unlikely. Electron paramagnetic resonance (EPR)-spin trapping data suggested that the fungicidal light-induced action of these derivatives might depend on the production of superoxide anion. The highest generation rate of superoxide anion was observed for 1330H, 1610H, and 1611. Singlet oxygen production was also detected upon the irradiation of imidazoacridinone derivatives with UV laser light, with a low to moderate yield, depending on the type of compound. Thus, imidazoacridinone derivatives examined in the present study might act via mixed type I/type II photodynamic mechanism. The presented data indicate lack of direct correlation between the structures of studied imidazoacridinones, cell killing ability, and ROS production. However, we showed for the first time that for imidazoacridinones not only intracellular accumulation is necessary prerequisite of lethal photosensitization of C. albicans, but also localization within particular cellular structures

  9. Photodynamic Inactivation of Candida albicans with Imidazoacridinones: Influence of Irradiance, Photosensitizer Uptake and Reactive Oxygen Species Generation.

    PubMed

    Taraszkiewicz, Aleksandra; Szewczyk, Grzegorz; Sarna, Tadeusz; Bielawski, Krzysztof P; Nakonieczna, Joanna

    2015-01-01

    The increasing applicability of antifungal treatments, the limited range of available drug classes and the emergence of drug resistance in Candida spp. suggest the need for new treatment options. To explore the applicability of C. albicans photoinactivation, we examined nine structurally different imidazoacridinone derivatives as photosensitizing agents. The most effective derivatives showed a >10(4)-fold reduction of viable cell numbers. The fungicidal action of the three most active compounds was compared at different radiant powers (3.5 to 63 mW/cm2), and this analysis indicated that 7 mW/cm2 was the most efficient. The intracellular accumulation of these compounds in fungal cells correlated with the fungicidal activity of all 9 derivatives. The lack of effect of verapamil, an inhibitor targeting Candida ABC efflux pumps, suggests that these imidazoacridinones are not substrates for ABC transporters. Thus, unlike azoles, a major class of antifungals used against Candida, ABC transporter-mediated resistance is unlikely. Electron paramagnetic resonance (EPR)-spin trapping data suggested that the fungicidal light-induced action of these derivatives might depend on the production of superoxide anion. The highest generation rate of superoxide anion was observed for 1330H, 1610H, and 1611. Singlet oxygen production was also detected upon the irradiation of imidazoacridinone derivatives with UV laser light, with a low to moderate yield, depending on the type of compound. Thus, imidazoacridinone derivatives examined in the present study might act via mixed type I/type II photodynamic mechanism. The presented data indicate lack of direct correlation between the structures of studied imidazoacridinones, cell killing ability, and ROS production. However, we showed for the first time that for imidazoacridinones not only intracellular accumulation is necessary prerequisite of lethal photosensitization of C. albicans, but also localization within particular cellular

  10. Cross-Validation of the Recumbent Stepper Submaximal Exercise Test to Predict Peak Oxygen Uptake in Older Adults

    PubMed Central

    Herda, Ashley A.; Lentz, Angela A.; Mattlage, Anna E.; Sisante, Jason-Flor

    2014-01-01

    Background Submaximal exercise testing can have a greater application in clinical settings because peak exercise testing is generally not available. In previous work, a prediction equation was developed to estimate peak oxygen consumption (V̇o2) using a total body recumbent stepper (TBRS) and the Young Men's Christian Association (YMCA) protocol in adults who were healthy. Objective The purpose of the present study was to cross-validate the TBRS peak V̇o2 prediction equation in older adults. Design A cross-sectional study was conducted. Methods Thirty participants (22 female, 8 male; mean age=66.8 years, SD=5.52; mean weight=68.51 kg, SD=13.39) who previously completed a peak exercise test and met the inclusion criteria were invited to participate in the cross-validation study. Within 5 days of the peak V̇o2 test, participants completed the TBRS submaximal exercise test. The TBRS submaximal exercise test equation was used to estimate peak V̇o2. The variables in the equation included age, weight, sex, watts (at the end of the submaximal exercise test), and heart rate (at the end of the submaximal exercise test). Results A strong correlation was found between the predicted peak V̇o2 and the measured peak V̇o2. The difference between the values was 0.9 mL·kg−1·min−1, which was not statistically different. The standard error of the estimate was 4.2 mL·kg−1·min−1. Limitations The sample included individuals who volunteered to perform a peak exercise test, which may have biased the results toward those willing to exercise to fatigue. Conclusion The data suggest the TBRS submaximal exercise test and prediction equation can be used to predict peak V̇o2 in older adults. This finding is important for health care professionals wanting to provide information to their patients or clients regarding their fitness level. PMID:24435104

  11. Uptake of 2S albumin allergens, Ber e 1 and Ses i 1, across human intestinal epithelial Caco-2 cell monolayers.

    PubMed

    Moreno, F Javier; Rubio, Luis A; Olano, Agustín; Clemente, Alfonso

    2006-11-01

    We have investigated the absorption rates of two purified major allergen 2S albumins, Ber e 1 from Brazil nuts (Bertholletia excelsa Humb. & Bonpl.) and Ses i 1 from white sesame seeds (Sesamum indicum L.), across human intestinal epithelial Caco-2 cell monolayers following gastrointestinal digestion in vitro. The transport from apical to basolateral side in cell monolayers was evaluated by RP-HPLC-UV and indirect competitive ELISA methods, being confirmed by western-blotting analysis. Significant amounts (approximately 15-25 nmol micromol(-1) initial amount/h) of intact Ber e 1 and Ses i 1 were found in the basolateral side. The absorption rates of both plant allergens through the cell monolayer were shown to be constant during the whole incubation period (4 h at 37 degrees C), verifying that the permeability of the membrane was not altered by the allergen digests. Our findings revealed that both purified 2S albumin allergens may be able to survive in immunologically reactive forms to the simulated harsh conditions of the gastrointestinal tract to be transported across the Caco-2 cell monolayers, so that they would be able to sensitize the mucosal immune system and/or elicit an allergic response. PMID:17061844

  12. Delta-aminolevulinate synthase 2 polymorphism is associated with maximal oxygen uptake after Living-high exercise-high training-low in a male Chinese population

    PubMed Central

    Xu, Yali; Hu, Yang; Ren, Zhijun; Yi, Longyan

    2015-01-01

    Objective: Each individual shows great variations to hypoxic training, which may be due to individual differences in genotype or gene polymorphism. δ-aminolevulinic acid synthase 2 (ALAS2) polymorphism is used as a marker for X-linked sideroblastic anemia. This study assessed the ALAS2 polymorphism for an association with response to Living-high exercise-high training-low (HiHiLo) training in Han Chinese males. Methods: A total of 244 healthy young male subjects of Han nationality were recruited from Northern China for detection of the ALAS2 polymorphism, 72 of whom were then selected for undergoing a four-week HiHiLo training program (i.e., subject to 10 h of hypoxia training daily at 14.5-14.8% O2 exposure, three occurrences of hypoxic training every week at 15.4% O2 level, and normal training at sea level). GeneScan and DNA sequencing were used to analyze ALAS2 polymorphism. Before and after training, the maximal oxygen uptake (VO2 max) in each individual was recorded. Results: A successive cut-point analysis showed that the initial hemoglobin value in individuals with dinucleotide repeats ≤ 166 bp was significantly higher than in individuals with dinucleotide repeats > 166-bp (P = 0.05). The ∆VO2 max and ∆rVO2 max after HiHiLo training were significantly higher in individuals with dinucleotide repeats ≤ 166 bp than in individuals with dinucleotide repeats > 166 bp (P < 0.01). Conclusions: The compound dinucleotide repeat polymorphism in ALAS2 intron 7 correlated with response to HiHiLo training. Further study will evaluate this ALAS2 SNP as a genetic marker to predict responses to HiHiLo training. PMID:26885114

  13. Long-term low-level laser therapy promotes an increase in maximal oxygen uptake and exercise performance in a dose-dependent manner in Wistar rats.

    PubMed

    Perini, Júlia Luiza; Hentschke, Vítor Scotta; Sonza, Anelise; Dal Lago, Pedro

    2016-02-01

    The use of low-level laser therapy (LLLT) represents a new intervention modality that has been explored to enhance exercise performance. The aim of this study was to evaluate the influence of LLLT (GaAIAs-850 nm) at different doses on VO2max and on exercise performance in rats. Male Wistar rats were divided into three groups: "placebo" rats (P-LLLT, n = 10), rats at a dose of 0.315 J per treatment point of LLLT (8.7 J/cm(2)-LLLT, n = 10), and rats at a dose of 2.205 J per treatment point of LLLT (61.2 J/cm(2)-LLLT, n = 10). The LLLT was applied bilaterally at the biceps femoris, gluteus, lateral and medial gastrocnemius, iliopsoas, and adductor longus muscles. One spot in each muscle belly was applied, with a sum of 12 spots in each rat, once a day, for 10 days. All animals performed the maximal exercise test (ET) at a metabolic treadmill for rats, with simultaneous gas analysis. The distance covered was measured during ET, before and after the conclusion of the LLLT protocol. The data were compared by a repeated measures two-way ANOVA followed by the Student-Newman-Keuls post hoc tests (p < .05). The 61.2 J/cm(2)-LLLT group increased VO2basal (~40 %), VO2max (~24 %), VCO2max (~17 %), and distance covered (~34 %) after LLLT application on the skeletal muscle. No significant results were found comparing before and after conditions for the studied variables considering P-LLLT and 8.7 J/cm(2)-LLLT groups. The LLLT promoted in a dose-dependent manner an increase in oxygen consumption uptake and a performance increment of male Wistar rats. PMID:26714977

  14. Absolute vs. weight-related maximum oxygen uptake in firefighters: fitness evaluation with and without protective clothing and self-contained breathing apparatus among age group.

    PubMed

    Perroni, Fabrizio; Guidetti, Laura; Cignitti, Lamberto; Baldari, Carlo

    2015-01-01

    During fire emergencies, firefighters wear personal protective devices (PC) and a self-contained breathing apparatus (S.C.B.A.) to be protected from injuries. The purpose of this study was to investigate the differences of aerobic level in 197 firefighters (age: 34±7 yr; BMI: 24.4±2.3 kg.m-2), evaluated by a Queen's College Step field Test (QCST), performed with and without fire protective garments, and to analyze the differences among age groups (<25 yr; 26-30 yr, 31-35 yr, 36-40 yr and >40 yr). Variance analysis was applied to assess differences (p < 0.05) between tests and age groups observed in absolute and weight-related values, while a correlation was examined between QCST with and without PC+S.C.B.A. The results have shown that a 13% of firefighters failed to complete the test with PC+S.C.B.A. and significant differences between QCST performed with and without PC+S.C.B.A. in absolute (F(1,169) = 42.6, p < 0.0001) and weight-related (F(1,169) = 339.9, p < 0.0001) terms. A better correlation has been found in L•min-1 (r=0.67) than in ml•kg-1•min-1 (r=0.54). Moreover, we found significant differences among age groups both in absolute and weight-related values. The assessment of maximum oxygen uptake of firefighters in absolute term can be a useful tool to evaluate the firefighters' cardiovascular strain. PMID:25764201

  15. Intestinal Malrotation

    MedlinePlus

    ... the intestines don't position themselves normally during fetal development and aren't attached inside properly as a result. The exact reason this occurs is unknown. When a fetus develops in the womb, the intestines start out ...

  16. Intestinal obstruction

    MedlinePlus

    ... of the major causes of intestinal obstruction in infants and children. Causes of paralytic ileus may include: Bacteria or viruses that cause intestinal infections ( gastroenteritis ) Chemical, electrolyte, or mineral imbalances (such as decreased ...

  17. Intestine Transplant

    MedlinePlus

    ... intestine segment, most intestine transplants involve a whole organ from a deceased donor. In addition, most intestine transplants are performed in ... blood before surgery. I am looking for ... allocation About UNOS Being a living donor Calculator - CPRA Calculator - KDPI Calculator - LAS Calculator - MELD ...

  18. Validation of a single-stage fixed-rate step test for the prediction of maximal oxygen uptake in healthy adults.

    PubMed

    Hansen, Dominique; Jacobs, Nele; Thijs, Herbert; Dendale, Paul; Claes, Neree

    2016-09-01

    Healthcare professionals with limited access to ergospirometry remain in need of valid and simple submaximal exercise tests to predict maximal oxygen uptake (VO2max ). Despite previous validation studies concerning fixed-rate step tests, accurate equations for the estimation of VO2max remain to be formulated from a large sample of healthy adults between age 18-75 years (n > 100). The aim of this study was to develop a valid equation to estimate VO2max from a fixed-rate step test in a larger sample of healthy adults. A maximal ergospirometry test, with assessment of cardiopulmonary parameters and VO2max , and a 5-min fixed-rate single-stage step test were executed in 112 healthy adults (age 18-75 years). During the step test and subsequent recovery, heart rate was monitored continuously. By linear regression analysis, an equation to predict VO2max from the step test was formulated. This equation was assessed for level of agreement by displaying Bland-Altman plots and calculation of intraclass correlations with measured VO2max . Validity further was assessed by employing a Jackknife procedure. The linear regression analysis generated the following equation to predict VO2max (l min(-1) ) from the step test: 0·054(BMI)+0·612(gender)+3·359(body height in m)+0·019(fitness index)-0·012(HRmax)-0·011(age)-3·475. This equation explained 78% of the variance in measured VO2max (F = 66·15, P<0·001). The level of agreement and intraclass correlation was high (ICC = 0·94, P<0·001) between measured and predicted VO2max . From this study, a valid fixed-rate single-stage step test equation has been developed to estimate VO2max in healthy adults. This tool could be employed by healthcare professionals with limited access to ergospirometry. PMID:26046474

  19. Oxygen uptake kinetics and maximal aerobic power are unaffected by inspiratory muscle training in healthy subjects where time to exhaustion is extended.

    PubMed

    Edwards, A M; Cooke, C B

    2004-10-01

    The aim of this study was to determine whether 4 weeks of inspiratory muscle training (IMT) would be accompanied by alteration in cardiopulmonary fitness as assessed through moderate intensity oxygen uptake (V(.)O(2)) kinetics and maximal aerobic power (V(.)O(2max)). Eighteen healthy males agreed to participate in the study [training group (Tra) n=10, control group (Con) n=8]. Measurements of spirometry and maximal static inspiratory mouth pressure ( PI(max)) were taken pre- and post-training in addition to: (1) an incremental test to volitional exhaustion, (2) three square-wave transitions from walking to running at a moderate intensity (80% ventilatory threshold) and (3) a maximal aerobic constant-load running test to volitional fatigue for the determination of time to exhaustion ( T(lim)). Training was performed using an inspiratory muscle trainer (Powerbreathe). There were no significant differences in spirometry either between the two groups or when comparing the post- to pre-training results within each group. Mean PI(max) increased significantly in Tra ( P<0.01) and showed a trend for improvement ( P<0.08) in Con. Post-training T(lim) was significantly extended in both Tra [232.4 (22.8) s and 242.8 (20.1) s] ( P<0.01) and Con [224.5 (19.6) and 233.5 (12.7) s] ( P<0.05). Post-training T(lim) was significantly extended in Tra compared to Con ( P<0.05). In conclusion, the most plausible explanation for the stability in V(.)O(2) kinetics and V(.)O(2max) following IMT is that it is due to insufficient whole-body stress to elicit either central or peripheral cardiopulmonary adaptation. The extension of post-training T(lim) suggests that IMT might be useful as a stratagem for producing greater volumes of endurance work at high ventilatory loads, which in turn could improve cardiopulmonary fitness. PMID:15322855

  20. A Review of Stature, Body Mass and Maximal Oxygen Uptake Profiles of U17, U20 and First Division Players in Brazilian Soccer

    PubMed Central

    Da Silva, Cristiano Diniz; Bloomfield, Jonathan; Marins, João Carlos Bouzas

    2008-01-01

    Investigations in the physiological demands of soccer have identified that a significant percentage of energy production in match performance is provided through the aerobic pathways. It is therefore important to assess maximal oxygen uptake (VO2Max) of players in order to evaluate their aerobic fitness status and optimize their physical conditioning. However, it is also important to consider the variation of (VO2Max) profiles for soccer players, with differences having been identified in terms of playing position as well as playing style. This paper reviews the academic literature between 1996 and 2006 and reports on the methodologies employed and the values obtained for stature, body mass and (VO2Max) profiles of soccer players of different positions in professional Brazilian clubs at U-17, U-20 and First Division levels. Indirect measurements accounted for the majority of tests conducted at U-17 (70%) and U-20 (84.6%) levels whereas at First Division level almost half of the (VO2Max) evaluations were performed by direct measurements (47.8%). The mean (VO2Max) profiles obtained for outfield players in U-17 was 56.95 ± 3.60 ml·kg-1·min-1, 58.13 ± 3.21 ml·kg-1·min-1 for U-20 players and 56.58 ± 5.03 ml·kg-1·min-1 for First Division players. In Brazil, the U-20 players appear to have highest VO2Max values, however the profiles reported for all outfield positions in U-17 and First Division levels are often lower than those reported for the same category of players from other countries. This may be a reflection of the style of play used in Brazilian soccer. This is further emphasized by the fact that the playing position with the highest VO2Max values was the external defenders whereas most findings from studies performed in European soccer indicate that midfielders require the highest VO2Max values. Key pointsPhysical and physiological differences exist between Brazilian soccer and European soccer.Players in Brazil appear to be shorter in stature, similar in

  1. Effect of supplementing a fibrous diet with a xylanase and β-glucanase blend on growth performance, intestinal glucose uptake, and transport-associated gene expression in growing pigs.

    PubMed

    Agyekum, A K; Sands, J S; Regassa, A; Kiarie, E; Weihrauch, D; Kim, W K; Nyachoti, C M

    2015-07-01

    The present study evaluated supplemental carbohydrase effect on performance, intestinal nutrient uptake, and transporter mRNA expressions in growing pigs offered a high-fiber diet manufactured with distillers dried grains with solubles (DDGS). Twenty-four pigs (22.4 ± 0.7 kg BW) were randomly assigned to 1of 3 nutritionally adequate diets (8 pigs per diet) based on corn and soybean meal (SBM) with either 0 (control) or 30% DDGS (high fiber [HF]). The third diet was supplemented with a xylanase and β-glucanase blend (XB) in addition to the 30% DDGS (HF+XB). Parameters determined were ADFI, ADG, G:F, plasma glucose and plasma urea nitrogen (PUN) concentrations, jejunal tissue electrophysiological properties, and mRNA expressions of the sodium-dependent glucose transport 1 (SGLT1) and cationic AA transporter, bo,+AT, in the jejunal and ileal tissues. In addition, mRNA expressions of the short-chain fatty acid transporters, monocarboxylate transporter 1 (MCT1) and sodium-coupled monocarboxylate transporter, and mucin genes were quantified in the ileum. Feed intake, plasma glucose, and jejunal tissue electrophysiological properties were not affected (P > 0.05) by diet. However, control-fed pigs had superior growth rate and feed efficiency and higher PUN (P < 0.05) than HF- and HF+XB-fed pigs. The HF diet increased (P < 0.05) SGLT1 mRNA expression in the jejunum and decreased (P < 0.05) bo,+ mRNA expression in the ileum. The XB supplementation also increased bo,+ mRNA expression in the ileum relative to HF-fed pigs. Additionally, MCT1 mRNA expression was greater (P < 0.05) in the ileum of the HF- and HF+XB-fed pigs. In the present study, XB supplementation influenced nutrient transporter mRNA expression, although it was not accompanied by improved pig performance. PMID:26440017

  2. Comparison of oxygen uptake during cycle ergometry with and without functional electrical stimulation in patients with COPD: protocol for a randomised, single-blind, placebo-controlled, cross-over trial

    PubMed Central

    Medrinal, Clément; Prieur, Guillaume; Debeaumont, David; Robledo Quesada, Aurora; Combret, Yann; Quieffin, Jean; Contal, Olivier; Lamia, Bouchra

    2016-01-01

    Introduction Chronic obstructive pulmonary disease (COPD) has systemic repercussions that can lead to peripheral muscle dysfunction. Muscle atrophy reduces aerobic capacity, greatly limiting activities of daily living and quality of life. Pulmonary rehabilitation is the gold standard treatment for these patients, however, patients may not be able to reach sufficient training intensities for benefits to occur. Technologies such as functional electrical stimulation (FES) are currently being adapted and tested to enhance exercise training. We hypothesise that FES coupled with cycling (FES-cycling) will improve maximal uptake of oxygen (VO2) and aerobic capacity more than endurance training with placebo stimulation. Methods A randomised, single-blind, placebo-controlled crossover trial will be carried out to evaluate the effects of FES-cycling on VO2 during endurance exercise on a cycle ergometer in patients with COPD. 25 patients with COPD will carry out two 30 min sessions at a constant load; one session with active and one with placebo FES. The primary outcome is oxygen uptake recorded with a metabolic measurement system. Secondary outcomes include ventilation equivalent for oxygen, ventilation equivalent for carbon dioxide, cardiac output, lactate values, perceived dyspnoea and perceived muscle fatigue. Results and conclusions Approval has been granted by our Institutional Review Board (Comité de Protection des Personnes Nord-Ouest 3). The results of the trial will be presented at national and international meetings and published in peer-reviewed journals. Trial registration number NCT02594722. PMID:27110364

  3. Intestinal transplantation.

    PubMed

    Rege, Aparna; Sudan, Debra

    2016-04-01

    Intestinal transplantation has now emerged as a lifesaving therapeutic option and standard of care for patients with irreversible intestinal failure. Improvement in survival over the years has justified expansion of the indications for intestinal transplantation beyond the original indications approved by Center for Medicare and Medicaid services. Management of patients with intestinal failure is complex and requires a multidisciplinary approach to accurately select candidates who would benefit from rehabilitation versus transplantation. Significant strides have been made in patient and graft survival with several advancements in the perioperative management through timely referral, improved patient selection, refinement in the surgical techniques and better understanding of the immunopathology of intestinal transplantation. The therapeutic efficacy of the procedure is well evident from continuous improvements in functional status, quality of life and cost-effectiveness of the procedure. This current review summarizes various aspects including current practices and evidence based recommendations of intestinal transplantation. PMID:27086894

  4. Glucagon increases hepatic oxygen supply-demand ratio in pigs

    SciTech Connect

    Gelman, S.; Dillard, E.; Parks, D.A.

    1987-05-01

    The present study was performed on eight young pigs to test the hypothesis that glucagon increases hepatic oxygen supply to a greater extent than hepatic oxygen uptake, providing a better hepatic oxygen supply-demand relationship. The experiments were performed under pentobarbital sodium anesthesia and controlled ventilation. Splanchnic blood flow was studied using radioactive microspheres. Glucagon was administered in doses of 1 and 5 ..mu..g x kg/sup -1/ x min/sup -1/. During glucagon infusion, hepatic arterial blood flow substantially increased, splenic and pancreatic blood flows increased moderately, while stomach and intestinal blood flows, as well as portal blood flow did not change significantly. Shunting of both 9- and 15-..mu..m spheres through preportal tissues did not change significantly. Oxygen content in arterial or portal venous blood did not change significantly, while it increased in hepatic venous blood by 30%. There were no differences in the effects between the doses of glucagon administered. There was no correlation found between changes in hepatic oxygen supply and cardiac output or blood pressure. The changes observed during glucagon administration resulted in an increase in oxygen delivery to the liver and hepatic oxygen supply-uptake ratio.

  5. INTESTINAL TRANSPLANTATION

    PubMed Central

    Tzakis, Andreas G.; Todo, Satoru; Starzl, Thomas E.

    2010-01-01

    Intestinal transplantation is often the only alternative form of treatment for patients dependent on total parenteral nutrition for survival. Although a limited number of intestinal transplantations have been performed, results with FK 506 immunosuppression are comparable to those for other organ transplants. The impact of successful intestinal transplantation on gastroenterology will likely be similar to the impact of kidney and liver transplantation on nephrology and hepatology. PMID:7515221

  6. Proton uptake in the H(+)-SOFC cathode material Ba(0.5)Sr(0.5)Fe(0.8)Zn(0.2)O(3-δ): transition from hydration to hydrogenation with increasing oxygen partial pressure.

    PubMed

    Poetzsch, Daniel; Merkle, Rotraut; Maier, Joachim

    2015-01-01

    Thermogravimetric investigations on the perovskite Ba(0.5)Sr(0.5)Fe(0.8)Zn(0.2)O(3-δ) (BSFZ, with mixed hole, oxygen vacancy and proton conductivity) from water vapor can occur by acid-base reaction (hydration) or redox reaction (hydrogen uptake), depending on the oxygen partial pressure, i.e. on the material's defect concentrations. In parallel, the effective diffusion coefficient of the stoichiometry relaxation kinetics also changes. These striking observations can be rationalized in terms of a defect chemical model and transport equations for materials with three mobile carriers. Implications for the search of cathode materials with mixed electronic and protonic conductivity for application on proton conducting oxide electrolytes are discussed. PMID:26206522

  7. Differences in reactive hyperemia between the intestinal mucosa and muscularis.

    PubMed

    Shepherd, A P; Riedel, G L

    1984-12-01

    In a previous study of regional intestinal blood flow by laser-Doppler velocimetry, we noted that the mucosa displayed reactive hyperemia following arterial occlusion but that the muscularis did not. Therefore, to determine whether this observation is generally valid, we compared responses of the mucosa and muscularis externa to arterial occlusion. We measured total blood flow to isolated loops of canine small bowel with an electromagnetic flow probe on the supply artery; blood flow either in the mucosa or in the muscularis was measured by laser-Doppler velocimetry. Mucosal and total blood flow consistently showed reactive hyperemia in response to a 60-s occlusion, but the muscularis did not. To determine whether metabolic rate influenced reactive hyperemia, we increased enteric oxygen uptake by placing 5% bile and transportable solutes in the lumen; these agents increased oxygen consumption by 36%. After a 60-s occlusion, the durations of both total and mucosal reactive hyperemia were significantly prolonged by increased metabolic rate. Similarly, the payback-to-debt ratios in both total and mucosal blood flows were significantly increased at elevated metabolic rate. These data support the conclusions that reactive hyperemia occurs more frequently and has a greater magnitude in the mucosa compared with the muscularis and both total and mucosal reactive hyperemia are strongly influenced by the preocclusive oxygen demand. These findings therefore constitute further evidence that metabolic factors contribute to reactive hyperemia in the intestinal circulation. PMID:6391202

  8. Intestinal absorption and biomagnification of organochlorines

    SciTech Connect

    Gobas, F.A.P.C. ); McCorquodale, J.R.; Haffner, G.D. )

    1993-03-01

    Dietary uptake rates of several organochlorines from diets with different lipid contents were measured in goldfish (Carassius auratus) to investigate the mechanism of intestinal absorption and biomagnification of organic chemical. The results suggest that intestinal absorption is predominantly controlled by chemical diffusion rather than lipid cotransport. Data for chemical uptake in human infants are presented to illustrate that biomagnification is caused by the digestion of food in the gastrointestinal tract. The findings are discussed in the context of two conflicting theories for the mechanism of biomagnification, and a mechanistic model is presented for the dietary uptake and biomagnification of organic chemicals in fish and mammals.

  9. The effect of gastric inhibitory polypeptide on intestinal glucose absorption and intestinal motility in mice

    SciTech Connect

    Ogawa, Eiichi; Hosokawa, Masaya; Harada, Norio; Yamane, Shunsuke; Hamasaki, Akihiro; Toyoda, Kentaro; Fujimoto, Shimpei; Fujita, Yoshihito; Fukuda, Kazuhito; Tsukiyama, Katsushi; Yamada, Yuichiro; Seino, Yutaka; Inagaki, Nobuya

    2011-01-07

    Research highlights: {yields} Exogenous GIP inhibits intestinal motility through a somatostatin-mediated pathway. {yields} Exogenous GIP inhibits intestinal glucose absorption by reducing intestinal motility. {yields} The GIP-receptor-mediated action in intestine does not involve in GLP-1-mediated pathway. -- Abstract: Gastric inhibitory polypeptide (GIP) is released from the small intestine upon meal ingestion and increases insulin secretion from pancreatic {beta} cells. Although the GIP receptor is known to be expressed in small intestine, the effects of GIP in small intestine are not fully understood. This study was designed to clarify the effect of GIP on intestinal glucose absorption and intestinal motility. Intestinal glucose absorption in vivo was measured by single-pass perfusion method. Incorporation of [{sup 14}C]-glucose into everted jejunal rings in vitro was used to evaluate the effect of GIP on sodium-glucose co-transporter (SGLT). Motility of small intestine was measured by intestinal transit after oral administration of a non-absorbed marker. Intraperitoneal administration of GIP inhibited glucose absorption in wild-type mice in a concentration-dependent manner, showing maximum decrease at the dosage of 50 nmol/kg body weight. In glucagon-like-peptide-1 (GLP-1) receptor-deficient mice, GIP inhibited glucose absorption as in wild-type mice. In vitro examination of [{sup 14}C]-glucose uptake revealed that 100 nM GIP did not change SGLT-dependent glucose uptake in wild-type mice. After intraperitoneal administration of GIP (50 nmol/kg body weight), small intestinal transit was inhibited to 40% in both wild-type and GLP-1 receptor-deficient mice. Furthermore, a somatostatin receptor antagonist, cyclosomatostatin, reduced the inhibitory effect of GIP on both intestinal transit and glucose absorption in wild-type mice. These results demonstrate that exogenous GIP inhibits intestinal glucose absorption by reducing intestinal motility through a somatostatin

  10. Min-By-Min Respiratory Exchange and Oxygen Uptake Kinetics During Steady-State Exercise in Subjects of High and Low Max VO2

    ERIC Educational Resources Information Center

    Weltman, Arthur; Katch, Victor

    1976-01-01

    No statistically meaningful differences in steady-state vo2 uptake for high and low max vo2 groups was indicated in this study, but a clear tendency was observed for the high max vo2 group to reach the steady-state at a faster rate. (MB)

  11. Intestinal Parasitoses.

    ERIC Educational Resources Information Center

    Lagardere, Bernard; Dumburgier, Elisabeth

    1994-01-01

    Intestinal parasites have become a serious public health problem in tropical countries because of the climate and the difficulty of achieving efficient hygiene. The objectives of this journal issue are to increase awareness of the individual and collective repercussions of intestinal parasites, describe the current conditions of contamination and…

  12. Intestinal Cancer

    MedlinePlus

    ... increase your risk. Possible signs of small intestine cancer include Abdominal pain Weight loss for no reason Blood in the stool A lump in the abdomen Imaging tests that create pictures of the small ... help diagnose intestinal cancer and show whether it has spread. Surgery is ...

  13. Intestinal steroidogenesis.

    PubMed

    Bouguen, Guillaume; Dubuquoy, Laurent; Desreumaux, Pierre; Brunner, Thomas; Bertin, Benjamin

    2015-11-01

    Steroids are fundamental hormones that control a wide variety of physiological processes such as metabolism, immune functions, and sexual characteristics. Historically, steroid synthesis was considered a function restricted to the adrenals and the gonads. In the past 20 years, a significant number of studies have demonstrated that steroids could also be synthesized or metabolized by other organs. According to these studies, the intestine appears to be a major source of de novo produced glucocorticoids as well as a tissue capable of producing and metabolizing sex steroids. This finding is based on the detection of steroidogenic enzyme expression as well as the presence of bioactive steroids in both the rodent and human gut. Within the intestinal mucosa, the intestinal epithelial cell layer is one of the main cellular sources of steroids. Glucocorticoid synthesis regulation in the intestinal epithelial cells is unique in that it does not involve the classical positive regulator steroidogenic factor-1 (SF-1) but a closely related homolog, namely the liver receptor homolog-1 (LRH-1). This local production of immunoregulatory glucocorticoids contributes to intestinal homeostasis and has been linked to pathophysiology of inflammatory bowel diseases. Intestinal epithelial cells also possess the ability to metabolize sex steroids, notably estrogen; this mechanism may impact colorectal cancer development. In this review, we contextualize and discuss what is known about intestinal steroidogenesis and regulation as well as the key role these functions play both in physiological and pathological conditions. PMID:25560486

  14. Intestinal obstruction

    MedlinePlus

    Obstruction of the bowel may due to: A mechanical cause, which means something is in the way ... lung disease Use of certain medicines, especially narcotics Mechanical causes of intestinal obstruction may include: Adhesions or ...

  15. The role of hypoxia in intestinal inflammation.

    PubMed

    Shah, Yatrik M

    2016-12-01

    Inflammatory bowel disease (IBD) is a chronic relapsing inflammatory disease of the intestine. IBD is a multifactorial disorder, and IBD-associated genes are critical in innate immune response, inflammatory response, autophagy, and epithelial barrier integrity. Moreover, epithelial oxygen tension plays a critical role in intestinal inflammation and resolution in IBD. The intestines have a dynamic and rapid fluctuation in cellular oxygen tension, which is dysregulated in IBD. Intestinal epithelial cells have a steep oxygen gradient where the tips of the villi are hypoxic and the oxygenation increases at the base of the villi. IBD results in heightened hypoxia throughout the mucosa. Hypoxia signals through a well-conserved family of transcription factors, where hypoxia-inducible factor (HIF)-1α and HIF-2α are essential in maintaining intestinal homeostasis. In inflamed mucosa, HIF-1α increases barrier protective genes, elicits protective innate immune responses, and activates an antimicrobial response through the increase in β-defensins. HIF-2α is essential in maintaining an epithelial-elicited inflammatory response and the regenerative and proliferative capacity of the intestine following an acute injury. HIF-1α activation in colitis leads to a protective response, whereas chronic activation of HIF-2α increases the pro-inflammatory response, intestinal injury, and cancer. In this mini-review, we detail the role of HIF-1α and HIF-2α in intestinal inflammation and injury and therapeutic implications of targeting HIF signaling in IBD. PMID:26812949

  16. Mechanisms underlying the protective effects of myricetin and quercetin following oxygen/glucose deprivation-induced cell swelling and the reduction in glutamate uptake in glial cells

    Technology Transfer Automated Retrieval System (TEKTRAN)

    C6 glial cells were exposed to oxygen-glucose deprivation (OGD) in cell culture for 5 hr and cell swelling was determined 90 min after the end of OGD. The OGD-induced increase in swelling was significantly blocked by the two flavonoids studied, quercetin and myricetin. The OGD-induced increase in ...

  17. Sublethal effect of silver and chromium in the green mussel Perna viridis with reference to alterations in oxygen uptake, filtration rate and membrane bound ATPase system as biomarkers.

    PubMed

    Vijayavel, K; Gopalakrishnan, S; Balasubramanian, M P

    2007-10-01

    Perna viridis is an ideal animal for studying the impairment caused by the effects of heavy metals that are often detected in coastal areas. Preliminary bioassay tests revealed that the lethal (LC(100)), median lethal (LC(50)) and sublethal (LC(0)) concentration of silver and chromium to P. viridis were 6.5, 4.0, 2.0 mg l(-1) and 4.5, 2.5, 1.0 mg l(-1), respectively. Toxic effect of silver and chromium was evaluated in the green mussel P. viridis, with reference to oxygen consumption, filtration rate and ATPase system in laboratory experiments. These parameters were selected as the end point of sublethal stress. Oxygen consumption and filtration rates were calculated as a measure of decline in the dissolved oxygen level and algal concentration (feed) in the aquaria water, respectively. Silver and chromium affects both oxygen consumption and filtration rate significantly (P<0.01) at 96 h when compared to control. The activity of ATPases system in the gills, hepatopancreas, ovary and muscle of mussels were inhibited by silver and chromium indicating that metals exerted significant toxic effect. The inhibition of Na(+)K(+) ATPase, Ca(2+) ATPase and Mg(2+) ATPase in the mussels were significant (P<0.05) for silver and highly significant (P<0.01) for chromium, which indicates that chromium was more toxic to mussels when compared to silver. The assessment of oxygen consumption, filtration and ATPases system can thus be used as a valid biomarker in aquatic ecotoxicology studies. PMID:17585996

  18. Uptake of triclopyr (3,5,6-trichloro-2-pyridinyloxyacetic acid) and dicamba (3,6-dichloro-2-methoxybenzoic acid) from the apical membranes of the human intestinal Caco-2 cells.

    PubMed

    Kimura, Osamu; Tsukagoshi, Kensuke; Hayasaka, Moriaki; Endo, Tetsuya

    2012-01-01

    We investigated whether the uptake of triclopyr (3, 5, 6-trichloro-2-pyridinyloxyacetic acid) and dicamba (3,6-dichloro-2-methoxybenzoic acid) across the apical membrane of Caco-2 cells was mediated via proton-linked monocarboxylic acid transporters (MCTs). The uptake of triclopyr from the apical membranes was fast, pH-, temperature-, and concentration dependent, required metabolic energy to proceed, and was competitively inhibited by monocarboxylic acids such as benzoic acid and ferulic acid (substrates of L-lactic acid-insensitive MCTs), but not by L-lactic acid. Thus, the uptake of triclopyr in Caco-2 cells appears to be mediated mainly via L-lactic acid-insensitive MCTs. In contrast, the uptake of dicamba (a benzoic acid derivative) was slow, and it was both pH- and temperature dependent. Coincubation with ferulic acid did not decrease the uptake of dicamba, although coincubation with benzoic acid moderately decreased it. The uptake of dicamba appears to be mediated mainly via passive diffusion, which is in contrast to the uptake of benzoic acid via MCTs. We speculate that the substituted groups in dicamba may inhibit uptake via MCTs. PMID:21766207

  19. Small Intestine Disorders

    MedlinePlus

    ... disease Crohn's disease Infections Intestinal cancer Intestinal obstruction Irritable bowel syndrome Ulcers, such as peptic ulcer Treatment of disorders of the small intestine depends on the cause.

  20. Intestinal Iron Homeostasis and Colon Tumorigenesis

    PubMed Central

    Xue, Xiang; Shah, Yatrik M.

    2013-01-01

    Colorectal cancer (CRC) is the third most common cause of cancer-related deaths in industrialized countries. Understanding the mechanisms of growth and progression of CRC is essential to improve treatment. Iron is an essential nutrient for cell growth. Iron overload caused by hereditary mutations or excess dietary iron uptake has been identified as a risk factor for CRC. Intestinal iron is tightly controlled by iron transporters that are responsible for iron uptake, distribution, and export. Dysregulation of intestinal iron transporters are observed in CRC and lead to iron accumulation in tumors. Intratumoral iron results in oxidative stress, lipid peroxidation, protein modification and DNA damage with consequent promotion of oncogene activation. In addition, excess iron in intestinal tumors may lead to increase in tumor-elicited inflammation and tumor growth. Limiting intratumoral iron through specifically chelating excess intestinal iron or modulating activities of iron transporter may be an attractive therapeutic target for CRC. PMID:23812305

  1. Effect of dissolved inorganic carbon on oxygen evolution and uptake by Chlamydomonas reinhardtii suspensions adapted to ambient and CO2-enriched air.

    PubMed

    Sültemeyer, D F; Klug, K; Fock, H P

    1987-01-01

    Mass spectrometric measurements of (16)O2 and (18)O2 isotopes were used to compare the rates of gross O2 evolution (E0), O2 uptake (U0) and net O2 evolution (NET) in relation to different concentrations of dissolved inorganic carbon (DIC) by Chlamydomonas reinhardtii cells grown in air (air-grown), in air enriched with 5% CO2 (CO2-grown) and by cells grown in 5% CO2 and then adapted to air for 6h (air-adapted).At a photon fluence rate (PFR) saturating for photosynthesis (700 μmol photons m(-2) s(-1)), pH=7.0 and 28°C, U0 equalled E0 at the DIC compensation point which was 10μM DIC for CO2-grown and zero for air-grown cells. Both E0 and U0 were strongly dependent on DIC and reached DIC saturation at 480 μM and 70 μM for CO2-grown and air-grown algae respectively. U0 increased from DIC compensation to DIC saturation. The U0 values were about 40 (CO2-grown), 165 (air-adapted) and 60 μmol O2 mg Chl(-1) h(-1) (air-grown). Above DIC compensation the U0/E0 ratios of air-adapted and air-grown algae were always higher than those of CO2-grown cells. These differences in O2 exchange between CO2- and air-grown algae seem to be inducable since air-adapted algae respond similarly to air-grown cells.For all algae, the rates of dark respiratory O2 uptake measured 5 min after darkening were considerably lower than the rates of O2 uptake just before darkening. The contribution of dark respiration, photorespiration and the Mehler reaction to U0 is discussed and the energy requirement of the inducable CO2/HCO3 (-) concentrating mechanism present in air-adapted and air-grown C. reinhardtii cells is considered. PMID:24435578

  2. Evaluation of Maximal Oxygen Uptake (V02max) and Submaximal Estimates of VO2max Before, During and After Long Duration ISS Missions

    NASA Technical Reports Server (NTRS)

    Moore, Alan; Evetts, Simon; Feiveson, Alan; Lee, Stuart; McCleary, Frank; Platts, Steven

    2009-01-01

    NASA's Human Research Program Integrated Research Plan (HRP-47065) serves as a road-map identifying critically needed information for future space flight operations (Lunar, Martian). VO2max (often termed aerobic capacity) reflects the maximum rate at which oxygen can be taken up and utilized by the body during exercise. Lack of in-flight and immediate postflight VO2max measurements was one area identified as a concern. The risk associated with not knowing this information is: Unnecessary Operational Limitations due to Inaccurate Assessment of Cardiovascular Performance (HRP-47065).

  3. Uptake of algal carbon and the synthesis of an "essential" fatty acid by Uvigerina ex. gr. semiornata (Foraminifera) within the Pakistan margin oxygen minimum zone: evidence from fatty acid biomarker and 13C tracer experiments

    NASA Astrophysics Data System (ADS)

    Larkin, K. E.; Gooday, A. J.; Woulds, C.; Jeffreys, R.; Schwartz, M.; Cowie, G.; Whitcraft, C.; Levin, L.; Dick, J. R.; Pond, D. W.

    2014-01-01

    Foraminifera are an important component of benthic communities in oxygen depleted settings, where they potentially play a~significant role in the processing of organic matter. We tracked the uptake of a 13C-labeled algal food source into individual fatty acids in the benthic foraminiferal species, Uvigerina ex. gr. semiornata, from the Arabian Sea oxygen minimum zone (OMZ). The tracer experiments were conducted on the Pakistan Margin during the late/post monsoon period (August-October 2003). A monoculture of the diatom Thalassiosira weisflogii was 13C-labeled and used to simulate a pulse of phytoplankton in two complementary experiments. A lander system was used for in situ incubations at 140 m and for 2.5 days duration, whilst a laboratory incubation used an oxystat system to maintain ambient dissolved oxygen concentrations. These shipboard experiments were terminated after 5 days. Uptake of diatoms was rapid, with high incorporation of diatom fatty acids into foraminifera after ~2 days in both experiments. Ingestion of the diatom food source was indicated by the increase over time in the quantity of diatom biomarker fatty acids in the foraminifera and by the high percentage of 13C in many of the fatty acids present at the endpoint of both in~situ and laboratory-based experiments. These results indicate that U. ex. gr. semiornata rapidly ingested the diatom food source and that this foraminifera will play an important role in the short-term cycling of organic matter within this OMZ environment. The experiments also suggested that U. ex. gr. semiornata consumed non-labeled bacterial food items, particularly bacteria, and synthesised the polyunsaturated fatty acid 20:4(n-6) de novo. 20:4(n-6) is often abundant in benthic fauna yet its origins and function have remained unclear. This study demonstrates that U. ex. gr. semiornata is capable of de novo synthesis of this "essential fatty acid" and is potentially a major source of this dietary nutrient in benthic food

  4. Uptake of algal carbon and the likely synthesis of an "essential" fatty acid by Uvigerina ex. gr. semiornata (Foraminifera) within the Pakistan margin oxygen minimum zone: evidence from fatty acid biomarker and 13C tracer experiments

    NASA Astrophysics Data System (ADS)

    Larkin, K. E.; Gooday, A. J.; Woulds, C.; Jeffreys, R. M.; Schwartz, M.; Cowie, G.; Whitcraft, C.; Levin, L.; Dick, J. R.; Pond, D. W.

    2014-07-01

    Foraminifera are an important component of benthic communities in oxygen-depleted settings, where they potentially play a significant role in the processing of organic matter. We tracked the uptake of a 13C-labelled algal food source into individual fatty acids in the benthic foraminiferal species Uvigerina ex. gr. semiornata from the Arabian Sea oxygen minimum zone (OMZ). The tracer experiments were conducted on the Pakistan margin during the late/post monsoon period (August-October 2003). A monoculture of the diatom Thalassiosira weisflogii was 13C-labelled and used to simulate a pulse of phytoplankton in two complementary experiments. A lander system was used for in situ incubations at 140 m water depth and for 2.5 days in duration. Shipboard laboratory incubations of cores collected at 140 m incorporated an oxystat system to maintain ambient dissolved oxygen concentrations and were terminated after 5 days. Uptake of diatoms was rapid, with a high incorporation of diatom fatty acids into foraminifera after ~ 2 days in both experiments. Ingestion of the diatom food source was indicated by the increase over time in the quantity of diatom biomarker fatty acids in the foraminifera and by the high percentage of 13C in many of the fatty acids present at the endpoint of both in situ and laboratory-based experiments. These results indicate that

  5. Direct measurement of the initial and early ratios of proton extrusion to oxygen uptake accompanying cytochrome c oxidation by rat liver mitoplasts.

    PubMed

    Hendler, R W; Setty, O H

    1988-02-01

    We have recently described new methods that enable the sharp initiation of a respiratory pulse by photolysis of the CO complex of cytochrome oxidase in a stirred suspension of mitochondria, succinate, O2, and CO (Setty, O. H., R. I. Shrager, B. Bunow, B. Reynafarje, A. L. Lehninger, and R. W. Hendler. 1986. Biophys. J. 50:391-404). Data are collected directly into a microcomputer at 10-ms intervals from fast responding O2 and pH electrodes. These procedures eliminate delays and uncertainties due to mixing times, recorder response, and recovery of the O2 electrode from responding to the injection of O2. Correction procedures were also described for the inherent electrode delays. These procedures revealed an initial burst in medium acidification and a lag in O2 uptake that led to H+/O rates of 20-30 during the first 50 ms and relaxed to "normal" levels by 300 ms. Subsequent changes in [H+] and [O2] followed time courses that appeared to be, but were not strictly, first order. We describe here similar studies in which cytochrome c served as electron donor to site III of rat liver mitoplasts. A qualitatively similar but quantitatively smaller burst in medium acidification and H+/O ratio was seen in these studies. Implications of the previous (Setty et al., 1986) and current studies on defining "mechanistic" H+/O ratios are discussed. PMID:2830923

  6. Intestinal Obstruction

    MedlinePlus

    ... the small intestine (duodenum) may be caused by cancer of the pancreas, scarring from an ulcer, or Crohn disease . Rarely, a gallstone, a mass of undigested food, or a collection of parasitic worms may block ... commonly caused by cancer, diverticulitis , or a hard lump of stool (fecal ...

  7. Influence of mechanical disintegration on the microbial growth of aerobic sludge biomass: A comparative study of ultrasonic and shear gap homogenizers by oxygen uptake measurements.

    PubMed

    Divyalakshmi, P; Murugan, D; Sivarajan, M; Saravanan, P; Lajapathi Rai, C

    2015-11-01

    Wastewater treatment plant incorporates physical, chemical and biological processes to treat and remove the contaminants. The main drawback of conventional activated sludge process is the huge production of excess sludge, which is an unavoidable byproduct. The treatment and disposal of excess sludge costs about 60% of the total operating cost. The ideal way to reduce excess sludge production during wastewater treatment is by preventing biomass formation within the aerobic treatment train rather than post treatment of the generated sludge. In the present investigation two different mechanical devices namely, Ultrasonic and Shear Gap homogenizers have been employed to disintegrate the aerobic biomass. This study is intended to restrict the multiplication of microbial biomass and at the same time degrade the organics present in wastewater by increasing the oxidative capacity of microorganisms. The disintegrability on biomass was determined by biochemical methods. Degree of inactivation provides the information on inability of microorganisms to consume oxygen upon disruption. The soluble COD quantifies the extent of release of intra cellular compounds. The participation of disintegrated microorganism in wastewater treatment process was carried out in two identical respirometeric reactors. The results show that Ultrasonic homogenizer is very effective in the disruption of microorganisms leading to a maximum microbial growth reduction of 27%. On the other hand, Shear gap homogenizer does not favor the sludge growth reduction rather it facilitates the growth. This study also shows that for better microbial growth reduction, floc size reduction alone is not sufficient but also microbial disruption is essential. PMID:25866205

  8. Coordination polymers of Fe(iii) and Al(iii) ions with TCA ligand: distinctive fluorescence, CO2 uptake, redox-activity and oxygen evolution reaction.

    PubMed

    Dhara, Barun; Sappati, Subrahmanyam; Singh, Santosh K; Kurungot, Sreekumar; Ghosh, Prasenjit; Ballav, Nirmalya

    2016-04-28

    Fe and Al belong to different groups in the periodic table, one from the p-block and the other from the d-block. In spite of their different groups, they have the similarity of exhibiting a stable 3+ oxidation state. Here we have prepared Fe(iii) and Al(iii) based coordination polymers in the form of metal-organic gels with the 4,4',4''-tricarboxyltriphenylamine (TCA) ligand, namely Fe-TCA and Al-TCA, and evaluated some important physicochemical properties. Specifically, the electrical conductivity, redox-activity, porosity, and electrocatalytic activity (oxygen evolution reaction) of the Fe-TCA system were noted to be remarkably higher than those of the Al-TCA system. As for the photophysical properties, almost complete quenching of the fluorescence originating from TCA was observed in case of the Fe-TCA system, whereas for the Al-TCA system a significant retention of fluorescence with red-shifted emission was observed. Quantum mechanical calculations based on density functional theory (DFT) were performed to unravel the origin of such discriminative behaviour of these coordination polymer systems. PMID:26961352

  9. [Intestinal endometriosis].

    PubMed

    González Rodríguez, C I; Cires, M; Jiménez, F J; Rubio, T

    2008-01-01

    Endometriosis is a chronic, benign gynaecological disorder that is frequent in women of a child-bearing age. It is estimated that there is some degree of endometriosis in as many as 15% of pre-menopausal women, associated with a history of infertility, caesarean antecedents, dysmenorrhoea and abnormality in uterine bleeding. It is believed to be due to the rise of menstrual contents through the Fallopian tubes (retrograde menstruation). In the intestinal affectation, the colon is the segment most frequently affected, above all at the rectosigmoidal level. The clinical features are unspecific, with abdominal pain the most frequent and/or pelvic pain of a cholic type that coincides with, or is exacerbated by, menstruation. Differential diagnosis includes intestinal inflammatory disease, diverticulitis, ischemic colitis and neoplastic processes, with the definitive diagnosis being anatomopathological. With respect to treatment, this will depend on the clinical features and the age of the patient, as well as her wishes with regard to pregnancy. PMID:18953367

  10. Autophagy and Intestinal Homeostasis

    PubMed Central

    Patel, Khushbu K.; Stappenbeck, Thaddeus S.

    2013-01-01

    Nutrient absorption is the basic function that drives mammalian intestinal biology. To facilitate nutrient uptake, the host’s epithelial barrier is composed of a single layer of cells. This constraint is problematic, as a design of this type can be easily disrupted. The solution during the course of evolution was to add numerous host defense mechanisms that can help prevent local and systemic infection. These mechanisms include specialized epithelial cells that produce a physiochemical barrier overlying the cellular barrier, robust and organized adaptive and innate immune cells, and the ability to mount an inflammatory response that is commensurate with a specific threat level. The autophagy pathway is a critical cellular process that strongly influences all these functions. Therefore, a fundamental understanding of the components of this pathway and their influence on inflammation, immunity, and barrier function will facilitate our understanding of homeostasis in the gastrointestinal tract. PMID:23216414

  11. Autophagy and intestinal homeostasis.

    PubMed

    Patel, Khushbu K; Stappenbeck, Thaddeus S

    2013-01-01

    Nutrient absorption is the basic function that drives mammalian intestinal biology. To facilitate nutrient uptake, the host's epithelial barrier is composed of a single layer of cells. This constraint is problematic, as a design of this type can be easily disrupted. The solution during the course of evolution was to add numerous host defense mechanisms that can help prevent local and systemic infection. These mechanisms include specialized epithelial cells that produce a physiochemical barrier overlying the cellular barrier, robust and organized adaptive and innate immune cells, and the ability to mount an inflammatory response that is commensurate with a specific threat level. The autophagy pathway is a critical cellular process that strongly influences all these functions. Therefore, a fundamental understanding of the components of this pathway and their influence on inflammation, immunity, and barrier function will facilitate our understanding of homeostasis in the gastrointestinal tract. PMID:23216414

  12. INTESTINAL OBSTRUCTION

    PubMed Central

    Cole, Warren H.

    1950-01-01

    Despite improvements in knowledge of the pathologic physiology of intestinal obstruction, the introduction of gastrointestinal decompression, and more effective antibiotics, obstruction remains a serious disease with a high mortality rate. Although the diagnosis is often obscure, it can usually be made with a fair degree of accuracy by the history alone; pain is fairly constant and characteristically is of a cramping type simulated by very few other lesions. Distention is present in low lesions but absent in high lesions; on the contrary, vomiting is minimal in low lesions but prominent in high lesions. Visible peristaltic waves are almost pathognomonic of intestinal obstruction. Increased peristaltic sounds, as noted by auscultation, are extremely helpful in diagnosis; they are absent in paralytic ileus. Although intestinal obstruction is a surgical lesion, it must be remembered that in the type produced by adhesions the obstruction can be relieved by gastrointestinal decompression in 80 to 90 per cent of cases. Operation is usually indicated a short time after relief because of the probability of recurrence. In practically all other types of obstruction decompression is indicated only while the patient is being prepared for operation. Obviously any type of strangulation demands early operation. Strangulation can usually be diagnosed, particularly if it develops while the patient is under observation. Increase in pain, muscle spasm and pulse rate are important indications of development of strangulation. Dehydration and electrolytic imbalance are produced almost universally in high obstruction. Usually, it is unwise to wait until these two deficiencies are corrected before operation is undertaken, but correction must be well under way at the time of operation. Resections should be avoided in the presence of intestinal obstruction, but obviously will be necessary in strangulation. Operative technique must be expert and carried out with minimal trauma. Postoperative

  13. Intestinal spirochaetosis

    PubMed Central

    Lee, F. D.; Kraszewski, A.; Gordon, J.; Howie, J. G. R.; McSeveney, D.; Harland, W. A.

    1971-01-01

    An abnormal condition of the large intestine is described in which the surface epithelium is infested by short spirochaetes. Diagnosis can be made by light microscopy. A review of 14 cases diagnosed by rectal biopsy and 62 cases involving the appendix shows no consistent symptom complex. The possible significance is discussed. ImagesFig. 2Fig. 3Fig. 4Fig. 5Fig. 6Fig. 1 PMID:5548558

  14. Small intestinal ischemia and infarction

    MedlinePlus

    ... small intestine; Atherosclerosis - small intestine; Hardening of the arteries - small intestine ... Embolus: Blood clots can block one of the arteries supplying the intestine. People who have had a ...

  15. Acute oxygen uptake and resistance exercise performance using different rest interval lengths: the influence of maximal aerobic capacity and exercise sequence.

    PubMed

    Ratamess, Nicholas A; Rosenberg, Joseph G; Kang, Jie; Sundberg, Samantha; Izer, Kerrie A; Levowsky, Jaclyn; Rzeszutko, Christina; Ross, Ryan E; Faigenbaum, Avery D

    2014-07-01

    The purpose of this study was to examine the relationship between VO2max and acute resistance exercise performance and the acute metabolic effects of exercise sequencing. Seventeen resistance-trained men were tested for VO2max and 1 repetition maximum (1RM) strength. Subjects were randomly assigned to either a group that performed the squat first in sequence followed by the bench press (S; n = 8) or a group that performed the bench press first followed by the squat (BP; n = 9). Each group performed 3 protocols (using 1-, 2-, or 3-minute rest intervals [RIs] between sets in random order) consisting of 5 sets of each exercise with 75% of their 1RM for up to 10 repetitions while oxygen consumption was measured. Total repetitions completed were highest with 3-minute RI and lowest with 1-minute RI. Mean VO2 was significantly highest with 1-minute RI and lowest using 3-minute RI. Analysis of each exercise revealed a tendency (p = 0.07) for mean bench press VO2 to be higher when it was performed after the squat using 1- and 2-minute RIs. VO2max was significantly negatively correlated to 1RM bench press and squat (r = -0.79 and -0.60, respectively) and was significantly correlated to squat repetitions (r = 0.43-0.57) but did not correlate to bench press performance. It seems that VO2max is related to lower-body resistance exercise performance when short RIs are used, and the metabolic response to the bench press is augmented when it follows the squat in sequence using short RIs. PMID:24714546

  16. ANTIBODIES TO INTESTINAL MICROVILLOUS MEMBRANES

    PubMed Central

    Mackenzie, Iain L.; Donaldson, Robert M.; Kopp, William L.; Trier, Jerry S.

    1968-01-01

    Microvillous membranes isolated from the distal, but not proximal, half of hamster small bowel induced in rabbits the formation of antisera which inhibited intrinsic factor-mediated uptake of vitamin B12 by hamster brush borders. The extent of inhibition was directly proportional to the concentration of antiserum, and an excess of IF-bound vitamin B12 could overcome the inhibitory effect. The inhibitory factor was absorbed from antisera by brush borders isolated from the distal, but not proximal, half of the hamster intestine. Fractionation of antisera by gel filtration and DEAE-cellulose chromatography established that immunoglobulin G contained the inhibitory factor. Antisera capable of completely blocking uptake of IF-bound vitamin B12 did not react with hamster IF or with the IF-vitamin B12 complex, did not inhibit brush border disaccharidase activity and did not impair glucose transport by everted sacs of hamster intestine. These results demonstrate that an antibody to distal microvillous membranes competes with the IF-vitamin B12 complex for a specific binding site or receptor located on the surface of distal hamster intestine. PMID:19867301

  17. Rates of total oxygen uptake of sediments and benthic nutrient fluxes measured using an in situ autonomous benthic chamber in the sediment of the slope off the southwestern part of Ulleung Basin, East Sea

    NASA Astrophysics Data System (ADS)

    Lee, Jae Seong; An, Sung-Uk; Park, Young-Gyu; Kim, Eunsoo; Kim, Dongseon; Kwon, Jung No; Kang, Dong-Jin; Noh, Jae-Hoon

    2015-09-01

    We have developed a new autonomous benthic lander for deep-sea research, the Korea Institute of Ocean Science and Technology (KIOST) Belc II and Belp II. The benthic lander was successfully tested at 950 and 1450 m water depths on the slope off the southwestern part of the Ulleung Basin in the East Sea of Korea. The ex situ measurements of the total oxygen uptake (TOU) rates at all the stations exceeded the in situ measurement values, and may indicate artificial effects from onboard incubation. The TOU rates were estimated to be 5.80 mmol m-2 d-1 and 3.77 mmol m-2 d-1 at water depths of 950 m and 1450 m, respectively. The benthic nutrient fluxes were also higher at water depths of 950 m, which indicates a partitioning of organic degradation with water depth. In addition, the negative phosphate and nitrogen benthic flux ratios and the higher nitrate removal flux via the sediment-water interface at the slope imply that the nitrogen in the bottom water may be preferentially removed via microbial respiration processes in the sediments, and may be coupled with the low nitrogen-to-phosphate ratio found in the deep water. Although our measurements comprised just two experiments in the slope sediment, the robust in situ measurement of the benthic fluxes in the slope sediment is a forerunner for new research into the biogeochemical cycles across the shelf edge-slope-basin system in the East Sea.

  18. Intestinal perfusion monitoring using photoplethysmography

    NASA Astrophysics Data System (ADS)

    Akl, Tony J.; Wilson, Mark A.; Ericson, M. Nance; Coté, Gerard L.

    2013-08-01

    In abdominal trauma patients, monitoring intestinal perfusion and oxygen consumption is essential during the resuscitation period. Photoplethysmography is an optical technique potentially capable of monitoring these changes in real time to provide the medical staff with a timely and quantitative measure of the adequacy of resuscitation. The challenges for using optical techniques in monitoring hemodynamics in intestinal tissue are discussed, and the solutions to these challenges are presented using a combination of Monte Carlo modeling and theoretical analysis of light propagation in tissue. In particular, it is shown that by using visible wavelengths (i.e., 470 and 525 nm), the perfusion signal is enhanced and the background contribution is decreased compared with using traditional near-infrared wavelengths leading to an order of magnitude enhancement in the signal-to-background ratio. It was further shown that, using the visible wavelengths, similar sensitivity to oxygenation changes could be obtained (over 50% compared with that of near-infrared wavelengths). This is mainly due to the increased contrast between tissue and blood in that spectral region and the confinement of the photons to the thickness of the small intestine. Moreover, the modeling results show that the source to detector separation should be limited to roughly 6 mm while using traditional near-infrared light, with a few centimeters source to detector separation leads to poor signal-to-background ratio. Finally, a visible wavelength system is tested in an in vivo porcine study, and the possibility of monitoring intestinal perfusion changes is showed.

  19. Enterocyte Fatty Acid Binding Proteins (FABPs): Different Functions of Liver- and Intestinal- FABPs in the Intestine

    PubMed Central

    Gajda, Angela M.; Storch, Judith

    2014-01-01

    SUMMARY Fatty acid binding proteins (FABP) are highly abundant cytosolic proteins that are expressed in most mammalian tissues. In the intestinal enterocyte, both Liver- (LFABP; FABP1) and Intestinal-fatty acid binding proteins (IFABP; FABP2) are expressed. These proteins display high affinity binding for long chain fatty acids (FA) and other hydrophobic ligands, thus they are believed to be involved with uptake and trafficking of lipids in the intestine. In vitro studies have identified differences in ligand binding stoichiometry and specificity, and in mechanisms of FA transfer to membranes, and it has been hypothesized that LFABP and IFABP have difference functions in the enterocyte. Studies directly comparing LFABP- and IFABP-null mice have revealed markedly different phenotypes, indicating that these proteins indeed have different functions in intestinal lipid metabolism and whole body energy homeostasis. In this review, we discuss the evolving knowledge of the functions of LFABP and IFABP in the intestinal enterocyte. PMID:25458898

  20. Large intestine (colon) (image)

    MedlinePlus

    The large intestine is the portion of the digestive system most responsible for absorption of water from the indigestible ... the ileum (small intestine) passes material into the large intestine at the cecum. Material passes through the ...

  1. Antigen sampling in the fish intestine.

    PubMed

    Løkka, Guro; Koppang, Erling Olaf

    2016-11-01

    Antigen uptake in the gastrointestinal tract may induce tolerance, lead to an immune response and also to infection. In mammals, most pathogens gain access to the host though the gastrointestinal tract, and in fish as well, this route seems to be of significant importance. The epithelial surface faces a considerable challenge, functioning both as a barrier towards the external milieu but simultaneously being the site of absorption of nutrients and fluids. The mechanisms allowing antigen uptake over the epithelial barrier play a central role for maintaining the intestinal homeostasis and regulate appropriate immune responses. Such uptake has been widely studied in mammals, but also in fish, a number of experiments have been reported, seeking to reveal cells and mechanisms involved in antigen sampling. In this paper, we review these studies in addition to addressing our current knowledge of the intestinal barrier in fish and its anatomical construction. PMID:26872546

  2. Intestinal capillariasis.

    PubMed Central

    Cross, J H

    1992-01-01

    Intestinal capillariasis caused by Capillaria philippinensis appeared first in the Philippines and subsequently in Thailand, Japan, Iran, Egypt, and Taiwan, but most infections occur in the Philippines and Thailand. As established experimentally, the life cycle involves freshwater fish as intermediate hosts and fish-eating birds as definitive hosts. Embryonated eggs from feces fed to fish hatch and grow as larvae in the fish intestines. Infective larvae fed to monkeys, Mongolian gerbils, and fish-eating birds develop into adults. Larvae become adults in 10 to 11 days, and the first-generation females produce larvae. These larvae develop into males and egg-producing female worms. Eggs pass with the feces, reach water, embryonate, and infect fish. Autoinfection is part of the life cycle and leads to hyperinfection. Humans acquire the infection by eating small freshwater fish raw. The parasite multiplies, and symptoms of diarrhea, borborygmus, abdominal pain, and edema develop. Chronic infections lead to malabsorption and hence to protein and electrolyte loss, and death results from irreversible effects of the infection. Treatment consists of electrolyte replacement and administration of an antidiarrheal agent and mebendazole or albendazole. Capillariasis philippinensis is considered a zoonotic disease of migratory fish-eating birds. The eggs are disseminated along flyways and infect the fish, and when fish are eaten raw, the disease develops. Images PMID:1576584

  3. Control of oxygen uptake during exercise.

    PubMed

    Poole, David C; Barstow, Thomas J; McDonough, Paul; Jones, Andrew M

    2008-03-01

    Other than during sleep and contrived laboratory testing protocols, humans rarely exist in prolonged metabolic steady states; rather, they transition among different metabolic rates (V O2). The dynamic transition of V O2 (V O2 kinetics), initiated, for example, at exercise onset, provides a unique window into understanding metabolic control. This brief review presents the state-of-the art regarding control of V O2 kinetics within the context of a simple model that helps explain the work rate dependence of V O2 kinetics as well as the effects of environmental perturbations and disease. Insights emerging from application of novel approaches and technologies are integrated into established concepts to assess in what circumstances O2 supply might exert a commanding role over V O2 kinetics, and where it probably does not. The common presumption that capillary blood flow dynamics can be extrapolated accurately from upstream arterial measurements is challenged. From this challenge, new complexities emerge with respect to the relationships between O2 supply and flux across the capillary-myocyte interface and the marked dependence of these processes on muscle fiber type. Indeed, because of interfiber type differences in O2 supply relative to V O2, the presence of much lower O2 levels in the microcirculation supplying fast-twitch muscle fibers, and the demonstrated metabolic sensitivity of muscle to O2, it is possible that fiber type recruitment profiles (and changes thereof) might help explain the slowing of V O2 kinetics at higher work rates and in chronic diseases such as heart failure and diabetes. PMID:18379208

  4. Robust bioengineered 3D functional human intestinal epithelium

    PubMed Central

    Chen, Ying; Lin, Yinan; Davis, Kimberly M.; Wang, Qianrui; Rnjak-Kovacina, Jelena; Li, Chunmei; Isberg, Ralph R.; Kumamoto, Carol A.; Mecsas, Joan; Kaplan, David L.

    2015-01-01

    Intestinal functions are central to human physiology, health and disease. Options to study these functions with direct relevance to the human condition remain severely limited when using conventional cell cultures, microfluidic systems, organoids, animal surrogates or human studies. To replicate in vitro the tissue architecture and microenvironments of native intestine, we developed a 3D porous protein scaffolding system, containing a geometrically-engineered hollow lumen, with adaptability to both large and small intestines. These intestinal tissues demonstrated representative human responses by permitting continuous accumulation of mucous secretions on the epithelial surface, establishing low oxygen tension in the lumen, and interacting with gut-colonizing bacteria. The newly developed 3D intestine model enabled months-long sustained access to these intestinal functions in vitro, readily integrable with a multitude of different organ mimics and will therefore ensure a reliable ex vivo tissue system for studies in a broad context of human intestinal diseases and treatments. PMID:26374193

  5. Cutaneous thermal injury alters macromolecular permeability of rat small intestine.

    PubMed

    Carter, E A; Tompkins, R G; Schiffrin, E; Burke, J F

    1990-03-01

    The intestinal epithelium normally provides a barrier function that prevents absorption of potentially harmful materials from the intestinal lumen. It has been postulated but never demonstrated that a cutaneous thermal injury will result in increased small-intestinal permeability. In a standardized 20% body surface area full-thickness scald injury, with polyethylene glycol 3350 and horseradish peroxidase used as permeability probes, small-intestinal permeability was examined regionally in an everted intestinal sac model. In the normal animals, the upper (proximal) and lower (distal) small intestine were less permeable to these probes than the middle segment. Within 6 hours after the injury, an increase in the mucosal uptake and transmural permeability was seen in all three small-intestinal segments; the most dramatic increase in permeability occurred in the ileum, p less than 0.01. The maximum increase in permeability was seen at 18 hours, and permeability was normal by 72 hours after the injury. This increase in intestinal permeability may represent a transient failure of the intestinal barrier function and may allow absorption of potentially toxic macromolecules from the intestinal lumen into the portal circulation early after thermal injury. Absorption of these macromolecules, such as endotoxin, may be potentially harmful by direct toxic actions or potentially helpful by activation of the immune system. PMID:2309150

  6. Nutritional Keys for Intestinal Barrier Modulation

    PubMed Central

    De Santis, Stefania; Cavalcanti, Elisabetta; Mastronardi, Mauro; Jirillo, Emilio; Chieppa, Marcello

    2015-01-01

    The intestinal tract represents the largest interface between the external environment and the human body. Nutrient uptake mostly happens in the intestinal tract, where the epithelial surface is constantly exposed to dietary antigens. Since inflammatory response toward these antigens may be deleterious for the host, a plethora of protective mechanisms take place to avoid or attenuate local damage. For instance, the intestinal barrier is able to elicit a dynamic response that either promotes or impairs luminal antigens adhesion and crossing. Regulation of intestinal barrier is crucial to control intestinal permeability whose increase is associated with chronic inflammatory conditions. The cross talk among bacteria, immune, and dietary factors is able to modulate the mucosal barrier function, as well as the intestinal permeability. Several nutritional products have recently been proposed as regulators of the epithelial barrier, even if their effects are in part contradictory. At the same time, the metabolic function of the microbiota generates new products with different effects based on the dietary content. Besides conventional treatments, novel therapies based on complementary nutrients are now growing. Fecal therapy has been recently used for the clinical treatment of refractory Clostridium difficile infection instead of the classical antibiotic therapy. In the present review, we will outline the epithelial response to nutritional components derived from dietary intake and microbial fermentation focusing on the consequent effects on the integrity of the epithelial barrier. PMID:26697008

  7. The pathophysiology of intestinal lipoprotein production

    PubMed Central

    Giammanco, Antonina; Cefalù, Angelo B.; Noto, Davide; Averna, Maurizio R.

    2015-01-01

    Intestinal lipoprotein production is a multistep process, essential for the absorption of dietary fats and fat-soluble vitamins. Chylomicron assembly begins in the endoplasmic reticulum with the formation of primordial, phospholipids-rich particles that are then transported to the Golgi for secretion. Several classes of transporters play a role in the selective uptake and/or export of lipids through the villus enterocytes. Once secreted in the lymph stream, triglyceride-rich lipoproteins (TRLs) are metabolized by Lipoprotein lipase (LPL), which catalyzes the hydrolysis of triacylglycerols of very low density lipoproteins (VLDLs) and chylomicrons, thereby delivering free fatty acids to various tissues. Genetic mutations in the genes codifying for these proteins are responsible of different inherited disorders affecting chylomicron metabolism. This review focuses on the molecular pathways that modulate the uptake and the transport of lipoproteins of intestinal origin and it will highlight recent findings on TRLs assembly. PMID:25852563

  8. Intestinal scavenger receptors are involved in vitamin K1 absorption.

    PubMed

    Goncalves, Aurélie; Margier, Marielle; Roi, Stéphanie; Collet, Xavier; Niot, Isabelle; Goupy, Pascale; Caris-Veyrat, Catherine; Reboul, Emmanuelle

    2014-10-31

    Vitamin K1 (phylloquinone) intestinal absorption is thought to be mediated by a carrier protein that still remains to be identified. Apical transport of vitamin K1 was examined using Caco-2 TC-7 cell monolayers as a model of human intestinal epithelium and in transfected HEK cells. Phylloquinone uptake was then measured ex vivo using mouse intestinal explants. Finally, vitamin K1 absorption was compared between wild-type mice and mice overexpressing scavenger receptor class B type I (SR-BI) in the intestine and mice deficient in cluster determinant 36 (CD36). Phylloquinone uptake by Caco-2 cells was saturable and was significantly impaired by co-incubation with α-tocopherol (and vice versa). Anti-human SR-BI antibodies and BLT1 (a chemical inhibitor of lipid transport via SR-BI) blocked up to 85% of vitamin K1 uptake. BLT1 also decreased phylloquinone apical efflux by ∼80%. Transfection of HEK cells with SR-BI and CD36 significantly enhanced vitamin K1 uptake, which was subsequently decreased by the addition of BLT1 or sulfo-N-succinimidyl oleate (CD36 inhibitor), respectively. Similar results were obtained in mouse intestinal explants. In vivo, the phylloquinone postprandial response was significantly higher, and the proximal intestine mucosa phylloquinone content 4 h after gavage was increased in mice overexpressing SR-BI compared with controls. Phylloquinone postprandial response was also significantly increased in CD36-deficient mice compared with wild-type mice, but their vitamin K1 intestinal content remained unchanged. Overall, the present data demonstrate for the first time that intestinal scavenger receptors participate in the absorption of dietary phylloquinone. PMID:25228690

  9. Intestinal Scavenger Receptors Are Involved in Vitamin K1 Absorption*

    PubMed Central

    Goncalves, Aurélie; Margier, Marielle; Roi, Stéphanie; Collet, Xavier; Niot, Isabelle; Goupy, Pascale; Caris-Veyrat, Catherine; Reboul, Emmanuelle

    2014-01-01

    Vitamin K1 (phylloquinone) intestinal absorption is thought to be mediated by a carrier protein that still remains to be identified. Apical transport of vitamin K1 was examined using Caco-2 TC-7 cell monolayers as a model of human intestinal epithelium and in transfected HEK cells. Phylloquinone uptake was then measured ex vivo using mouse intestinal explants. Finally, vitamin K1 absorption was compared between wild-type mice and mice overexpressing scavenger receptor class B type I (SR-BI) in the intestine and mice deficient in cluster determinant 36 (CD36). Phylloquinone uptake by Caco-2 cells was saturable and was significantly impaired by co-incubation with α-tocopherol (and vice versa). Anti-human SR-BI antibodies and BLT1 (a chemical inhibitor of lipid transport via SR-BI) blocked up to 85% of vitamin K1 uptake. BLT1 also decreased phylloquinone apical efflux by ∼80%. Transfection of HEK cells with SR-BI and CD36 significantly enhanced vitamin K1 uptake, which was subsequently decreased by the addition of BLT1 or sulfo-N-succinimidyl oleate (CD36 inhibitor), respectively. Similar results were obtained in mouse intestinal explants. In vivo, the phylloquinone postprandial response was significantly higher, and the proximal intestine mucosa phylloquinone content 4 h after gavage was increased in mice overexpressing SR-BI compared with controls. Phylloquinone postprandial response was also significantly increased in CD36-deficient mice compared with wild-type mice, but their vitamin K1 intestinal content remained unchanged. Overall, the present data demonstrate for the first time that intestinal scavenger receptors participate in the absorption of dietary phylloquinone. PMID:25228690

  10. Transcriptomic responses in the fish intestine.

    PubMed

    Martin, Samuel A M; Dehler, Carola E; Król, Elżbieta

    2016-11-01

    The intestine, being a multifunctional organ central to both nutrient uptake, pathogen recognition and regulating the intestinal microbiome, has been subjected to intense research. This review will focus on the recent studies carried out using high-throughput gene expression approaches, such as microarray and RNA sequencing (RNA-seq). These techniques have advanced greatly in recent years, mainly as a result of the massive changes in sequencing methodologies. At the time of writing, there is a transition between relatively well characterised microarray platforms and the developing RNA-seq, with the prediction that within a few years as costs decrease and computation power increase, RNA-seq related approaches will supersede the microarrays. Comparisons between the approaches are made and specific examples of how the techniques have been used to examine intestinal responses to pathogens, dietary manipulations and osmoregulatory challenges are given. PMID:26995769

  11. Identification of an intestinal heme transporter.

    PubMed

    Shayeghi, Majid; Latunde-Dada, Gladys O; Oakhill, Jonathan S; Laftah, Abas H; Takeuchi, Ken; Halliday, Neil; Khan, Yasmin; Warley, Alice; McCann, Fiona E; Hider, Robert C; Frazer, David M; Anderson, Gregory J; Vulpe, Christopher D; Simpson, Robert J; McKie, Andrew T

    2005-09-01

    Dietary heme iron is an important nutritional source of iron in carnivores and omnivores that is more readily absorbed than non-heme iron derived from vegetables and grain. Most heme is absorbed in the proximal intestine, with absorptive capacity decreasing distally. We utilized a subtractive hybridization approach to isolate a heme transporter from duodenum by taking advantage of the intestinal gradient for heme absorption. Here we show a membrane protein named HCP 1 (heme carrier protein 1), with homology to bacterial metal-tetracycline transporters, mediates heme uptake by cells in a temperature-dependent and saturable manner. HCP 1 mRNA was highly expressed in duodenum and regulated by hypoxia. HCP 1 protein was iron regulated and localized to the brush-border membrane of duodenal enterocytes in iron deficiency. Our data indicate that HCP 1 is the long-sought intestinal heme transporter. PMID:16143108

  12. Role of Intestinal HIF-2α in Health and Disease.

    PubMed

    Ramakrishnan, Sadeesh K; Shah, Yatrik M

    2016-01-01

    The intestine is supported by a complex vascular system that undergoes dynamic and transient daily shifts in blood perfusion, depending on the metabolic state. Moreover, the intestinal villi have a steep oxygen gradient from the hypoxic epithelium adjacent to the anoxic lumen to the relative higher tissue oxygenation at the base of villi. Due to the daily changes in tissue oxygen levels in the intestine, the hypoxic transcription factors hypoxia-inducible factor (HIF)-1α and HIF-2α are essential in maintaining intestinal homeostasis. HIF-2α is essential in maintaining proper micronutrient balance, the inflammatory response, and the regenerative and proliferative capacity of the intestine following an acute injury. However, chronic activation of HIF-2α leads to enhanced proinflammatory response, intestinal injury, and colorectal cancer. In this review, we detail the major mechanisms by which HIF-2α contributes to health and disease of the intestine and the therapeutic implications of targeting HIF-2α in intestinal diseases. PMID:26667076

  13. Vasoactive intestinal peptide test

    MedlinePlus

    ... medlineplus.gov/ency/article/003508.htm Vasoactive intestinal peptide test To use the sharing features on this page, please enable JavaScript. Vasoactive intestinal peptide (VIP) is a test that measures the amount ...

  14. Intestinal transport as a potential determinant of drug bioavailability.

    PubMed

    Nauli, Andromeda M; Nauli, Surya M

    2013-08-01

    Orally administered drugs are generally absorbed by the small intestine and transported either to the lymphatic system or to the hepatic portal system. In general, lipid soluble drugs and vitamins are transported by the small intestine to the lymphatics, and water-soluble drugs are transported to the hepatic portal system. By avoiding the early hepatic first pass effect, the lymphatic transport system may increase drug bioavailability. In addition to its transport systems, the small intestine may affect drug bioavailability through drug uptake, intestinal first pass effect, recruitment of drugs by chylomicrons, formation and secretion of chylomicrons, and enterohepatic circulation. All of these factors should be considered when formulating orally administered lipophilic drugs. Our data also suggest that Caco-2 cells may serve as a valuable in vitro model to study the intestinal transport of orally administered drugs. PMID:23343017

  15. Vertebrate Intestinal Endoderm Development

    PubMed Central

    Spence, Jason R.; Lauf, Ryan; Shroyer, Noah F.

    2010-01-01

    The endoderm gives rise to the lining of the esophagus, stomach and intestines, as well as associated organs. To generate a functional intestine, a series of highly orchestrated developmental processes must occur. In this review, we attempt to cover major events during intestinal development from gastrulation to birth, including endoderm formation, gut tube growth and patterning, intestinal morphogenesis, epithelial reorganization, villus emergence as well as proliferation and cytodifferentiation. Our discussion includes morphological and anatomical changes during intestinal development as well as molecular mechanisms regulating these processes. PMID:21246663

  16. Enterocyte fatty acid-binding proteins (FABPs): different functions of liver and intestinal FABPs in the intestine.

    PubMed

    Gajda, Angela M; Storch, Judith

    2015-02-01

    Fatty acid-binding proteins (FABP) are highly abundant cytosolic proteins that are expressed in most mammalian tissues. In the intestinal enterocyte, both liver- (LFABP; FABP1) and intestinal FABPs (IFABP; FABP2) are expressed. These proteins display high-affinity binding for long-chain fatty acids (FA) and other hydrophobic ligands; thus, they are believed to be involved with uptake and trafficking of lipids in the intestine. In vitro studies have identified differences in ligand-binding stoichiometry and specificity, and in mechanisms of FA transfer to membranes, and it has been hypothesized that LFABP and IFABP have different functions in the enterocyte. Studies directly comparing LFABP- and IFABP-null mice have revealed markedly different phenotypes, indicating that these proteins indeed have different functions in intestinal lipid metabolism and whole body energy homeostasis. In this review, we discuss the evolving knowledge of the functions of LFABP and IFABP in the intestinal enterocyte. PMID:25458898

  17. Establishment of Intestinal Bacteriology

    PubMed Central

    MITSUOKA, Tomotari

    2014-01-01

    Research on intestinal bacteria began around the end of the 19th century. During the last 5 decades of the 20th century, research on the intestinal microbiota made rapid progress. At first, in my work, I first developed a method of comprehensive analysis of the intestinal microbiota, and then I established classification and identification methods for intestinal anaerobes. Using these methods I discovered a number of ecological rules governing the intestinal microbiota and the role of the intestinl microbiota in health and disease. Moreover, using germfree animals, it was proven that the intestinal microbiota has a role in carcinogenesis and aging in the host. Thus, a new interdisciplinary field, “intestinal bacteriology” was established. PMID:25032084

  18. Rat splanchnic net oxygen consumption, energy implications.

    PubMed Central

    Casado, J; Fernández-López, J A; Esteve, M; Rafecas, I; Argilés, J M; Alemany, M

    1990-01-01

    1. The blood flow, PO2, pH and PCO2 have been estimated in portal and suprahepatic veins as well as in hepatic artery of fed and overnight starved rats given an oral glucose load. From these data the net intestinal, hepatic and splanchnic balances for oxygen and bicarbonate were calculated. The oxygen consumption of the intact animal has also been measured under comparable conditions. 2. The direct utilization of oxygen balances as energy equivalents when establishing the contribution of energy metabolism of liver and intestine to the overall energy expenses of the rat, has been found to be incorrect, since it incorporates the intrinsic error of interorgan proton transfer through bicarbonate. Liver and intestine produced high net bicarbonate balances in all situations tested, implying the elimination (by means of oxidative pathways, i.e. consuming additional oxygen) of high amounts of H+ generated with bicarbonate. The equivalence in energy output of the oxygen balances was then corrected for bicarbonate production to 11-54% lower values. 3. Intestine and liver consume a high proportion of available oxygen, about one-half in basal (fed or starved) conditions and about one-third after gavage, the intestine consumption being about 15% in all situations tested and the liver decreasing its oxygen consumption with gavage. PMID:2129230

  19. Effect of oxygen pressure during incubation with a (10)B-carrier on (10)B uptake capacity of cultured p53 wild-type and mutated tumor cells: dependency on p53 status of tumor cells and types of (10)B-carriers.

    PubMed

    Masunaga, Shin-ichiro; Tatebe, Hitoshi; Nishimura, Yasumasa; Tano, Keizo; Sanada, Yu; Moriwaki, Takahiro; Sakurai, Yoshinori; Tanaka, Hiroki; Suzuki, Minoru; Kondo, Natsuko; Maruhashi, Akira; Ono, Koji

    2016-01-01

    Purpose To evaluate the effect of oxygen pressure during incubation with a (10)B-carrier on (10)B uptake capacity of cultured p53 wild-type and mutated tumor cells. Materials and methods Cultured human head and neck squamous cell carcinoma cell line transfected with mutant TP53 (SAS/mp53), or with a neo vector as a control (SAS/neo) was incubated with L-para-boronophenylalanine-(10)B (BPA) or sodium mercaptoundecahydrododecaborate-(10)B (BSH) as a (10)B-carrier at the (10)B concentration of 60 ppm for 24 h under aerobic (20.7% of oxygen) or hypoxic (0.28% of oxygen) conditions. Immediately after incubation, cultured tumor cells received reactor thermal neutron beams, and a cell survival assay was performed. (10)B concentration of cultured SAS/neo or SAS/mp53 cells incubated under aerobic or hypoxic conditions was determined with a thermal neutron guide tube. Results Hypoxic incubation significantly decreased (10)B concentration of cultured cells with a clearer tendency observed following BPA than BSH treatment in both SAS/neo and SAS/mp53 cells. Following neutron beam irradiation, SAS/mp53 cells showed significantly higher relative biological effectiveness values than SAS/neo cells because of the significantly lower radiosensitivity of SAS/mp53 to γ-rays than SAS/neo cells. Conclusion Oxygen pressure during incubation with a (10)B-carrier had a critical impact on (10)B uptake of cultured tumor cells. PMID:26887694

  20. Oxygen Therapy

    MedlinePlus

    Oxygen therapy is a treatment that provides you with extra oxygen. Oxygen is a gas that your body needs to function. Normally, your lungs absorb oxygen from the air you breathe. But some conditions ...

  1. Examining urea flux across the intestine of the spiny dogfish, Squalus acanthias.

    PubMed

    Gary Anderson, W; McCabe, Chris; Brandt, Catherine; Wood, Chris M

    2015-03-01

    Recent examination of urea flux in the intestine of the spiny dogfish shark, Squalus acanthias, has shown that feeding significantly enhances urea uptake across the intestine, and this was significantly inhibited following mucosal addition of phloretin. The present study examined potential mechanisms of urea uptake across the dogfish intestine in starved and fed dogfish. Unidirectional flux chambers were used to examine the kinetics of urea uptake, and to determine the influence of sodium, ouabain, competitive urea analogues, and phloretin on urea uptake across the gut of fed dogfish. Intestinal epithelial preparations from starved and fed dogfish were mounted in Ussing chambers to examine the effect of phloretin on bidirectional solute transport across the intestine. In the unidirectional studies, the maximum uptake rate of urea was found to be 35.3±6.9 μmol.cm(-2).h(-1) and Km was found to be 291.8±9.6 mM in fed fish, and there was a mild inhibition of urea uptake following mucosal addition of competitive agonists. Addition of phloretin, Na-free Ringers and ouabain to the mucosal side of intestinal epithelia also led to a significant reduction in urea uptake in fed fish. In the Ussing chamber studies there was a net influx of urea in fed fish and a small insignificant efflux in starved fish. Addition of phloretin blocked urea uptake in fed fish when added to the mucosal side. Furthermore, phloretin had no effect on ion transport across the intestinal epithelia with the exception of the divalent cations, magnesium and calcium. PMID:25479361

  2. Microbiota regulate intestinal absorption and metabolism of fatty acids in the zebrafish

    PubMed Central

    Semova, Ivana; Carten, Juliana D.; Stombaugh, Jesse; Mackey, Lantz C.; Knight, Rob; Farber, Steven A.; Rawls, John F.

    2012-01-01

    SUMMARY Regulation of intestinal dietary fat absorption is critical to maintaining energy balance. While intestinal microbiota clearly impact the host’s energy balance, their role in intestinal absorption and extra-intestinal metabolism of dietary fat is less clear. Using in vivo imaging of fluorescent fatty acid (FA) analogs delivered to gnotobiotic zebrafish hosts, we reveal that microbiota stimulate FA uptake and lipid droplet (LD) formation in the intestinal epithelium and liver. Microbiota increase epithelial LD number in a diet-dependent manner. The presence of food led to the intestinal enrichment of bacteria from the phylum Firmicutes. Diet-enriched Firmicutes and their products were sufficient to increase epithelial LD number, whereas LD size was increased by other bacterial types. Thus, different members of the intestinal microbiota promote FA absorption via distinct mechanisms. Diet-induced alterations in microbiota composition might influence fat absorption, providing mechanistic insight into how microbiota-diet interactions regulate host energy balance. PMID:22980325

  3. Dosimetry Model for Radioactivity Localized to Intestinal Mucosa

    SciTech Connect

    Fisher, Darrell R.; Rajon, Didier; Breitz, Hazel B.; Goris, Michael L.; Bolch, Wesley E.; Knox, Susan J.

    2004-06-30

    This paper provides a new model for calculating radiation absorbed dose to the full thickness of the small and large intestinal walls, and to the mucosal layers. The model was used to estimate the intestinal radiation doses from yttrium-90-labeled-DOTA-biotin binding to NR-LU-10-streptavidin in patients. We selected model parameters from published data and observations and used the model to calculate energy absorbed fractions using the EGS4 radiation transport code. We determined the cumulated 90Y activity in the small and large intestines of patients from gamma camera images and calculated absorbed doses to the mucosal layer and to the whole intestinal wall. The mean absorbed dose to the wall of the small intestine was 16.2 mGy/MBq (60 cGy/mCi) administered from 90Y localized in the mucosa and 70 mGy/MBq (260 cGy/mCi) to the mucosal layer within the wall. Doses to the large intestinal wall and to the mucosa of the large intestine were lower than those for small intestine by a factor of about 2.5. These doses are greater by factors of about 5 to 6 than those that would have been calculated using the standard MIRD models that assume the intestinal activity is in the bowel contents. The specific uptake of radiopharmaceuticals in mucosal tissues may lead to dose-related intestinal toxicities. Tissue dosimetry at the sub-organ level is useful for better understanding intestinal tract radiotoxicity and associated dose-response relationships.

  4. Intestinal lymphangiectasia in children

    PubMed Central

    Isa, Hasan M.; Al-Arayedh, Ghadeer G.; Mohamed, Afaf M.

    2016-01-01

    Intestinal lymphangiectasia (IL) is a rare disease characterized by dilatation of intestinal lymphatics. It can be classified as primary or secondary according to the underlying etiology. The clinical presentations of IL are pitting edema, chylous ascites, pleural effusion, acute appendicitis, diarrhea, lymphocytopenia, malabsorption, and intestinal obstruction. The diagnosis is made by intestinal endoscopy and biopsies. Dietary modification is the mainstay in the management of IL with a variable response. Here we report 2 patients with IL in Bahrain who showed positive response to dietary modification. PMID:26837404

  5. Salmonella infection inhibits intestinal biotin transport: cellular and molecular mechanisms

    PubMed Central

    Ghosal, Abhisek; Jellbauer, Stefan; Kapadia, Rubina; Raffatellu, Manuela

    2015-01-01

    Infection with the nontyphoidal Salmonella is a common cause of food-borne disease that leads to acute gastroenteritis/diarrhea. Severe/prolonged cases of Salmonella infection could also impact host nutritional status, but little is known about its effect on intestinal absorption of vitamins, including biotin. We examined the effect of Salmonella enterica serovar Typhimurium (S. typhimurium) infection on intestinal biotin uptake using in vivo (streptomycin-pretreated mice) and in vitro [mouse (YAMC) and human (NCM460) colonic epithelial cells, and human intestinal epithelial Caco-2 cells] models. The results showed that infecting mice with wild-type S. typhimurium, but not with its nonpathogenic isogenic invA spiB mutant, leads to a significant inhibition in jejunal/colonic biotin uptake and in level of expression of the biotin transporter, sodium-dependent multivitamin transporter. In contrast, infecting YAMC, NCM460, and Caco-2 cells with S. typhimurium did not affect biotin uptake. These findings suggest that the effect of S. typhimurium infection is indirect and is likely mediated by proinflammatory cytokines, the levels of which were markedly induced in the intestine of S. typhimurium-infected mice. Consistent with this hypothesis, exposure of NCM460 cells to the proinflammatory cytokines TNF-α and IFN-γ led to a significant inhibition of biotin uptake, sodium-dependent multivitamin transporter expression, and activity of the SLC5A6 promoter. The latter effects appear to be mediated, at least in part, via the NF-κB signaling pathway. These results demonstrate that S. typhimurium infection inhibits intestinal biotin uptake, and that the inhibition is mediated via the action of proinflammatory cytokines. PMID:25999427

  6. AMINO ACIDS MODULATE INTESTINAL ZINC UPTAKE IN FISH. (R826104)

    EPA Science Inventory

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  7. IN VIVO INTESTINAL ZINC UPTAKE IN FRESHWATER TROUT. (R826104)

    EPA Science Inventory

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  8. [The biliary intestinal obstruction].

    PubMed

    Demetrashvili, Z M; Asatiani, G A; Nemsadze, G Sh; Kenchadze, G Z

    2012-01-01

    The successful experience of treatment of 3 patients with biliary intestinal obstruction is depicted. The most informative means of diagnostics was the multispiral computed tomography. Authors state, that the volume of the operation should include only the liquidation of the intestinal obstruction. The simultaneous biliodigestive fistulae closure should be performed only in rare situations. PMID:22678540

  9. Hydroxyethyl Starch (HES 130/0.4) Impairs Intestinal Barrier Integrity and Metabolic Function: Findings from a Mouse Model of the Isolated Perfused Small Intestine

    PubMed Central

    Dombrowsky, Heike; Zitta, Karina; Bein, Berthold; Krause, Thorsten; Goldmann, Torsten; Frerichs, Inez; Steinfath, Markus; Weiler, Norbert; Albrecht, Martin

    2015-01-01

    Background The application of hydroxyethyl starch (HES) for volume resuscitation is controversially discussed and clinical studies have suggested adverse effects of HES substitution, leading to increased patient mortality. Although, the intestine is of high clinical relevance and plays a crucial role in sepsis and inflammation, information about the effects of HES on intestinal function and barrier integrity is very scarce. We therefore evaluated the effects of clinically relevant concentrations of HES on intestinal function and barrier integrity employing an isolated perfused model of the mouse small intestine. Methods An isolated perfused model of the mouse small intestine was established and intestines were vascularly perfused with a modified Krebs-Henseleit buffer containing 3% Albumin (N=7) or 3% HES (130/0.4; N=7). Intestinal metabolic function (galactose uptake, lactate-to-pyruvate ratio), edema formation (wet-to-dry weight ratio), morphology (histological and electron microscopical analysis), fluid shifts within the vascular, lymphatic and luminal compartments, as well as endothelial and epithelial barrier permeability (FITC-dextran translocation) were evaluated in both groups. Results Compared to the Albumin group, HES perfusion did not significantly change the wet-to-dry weight ratio and lactate-to-pyruvate ratio. However, perfusing the small intestine with 3% HES resulted in a significant loss of vascular fluid (p<0.01), an increased fluid accumulation in the intestinal lumen (p<0.001), an enhanced translocation of FITC-dextran from the vascular to the luminal compartment (p<0.001) and a significantly impaired intestinal galactose uptake (p<0.001). Morphologically, these findings were associated with an aggregation of intracellular vacuoles within the intestinal epithelial cells and enlarged intercellular spaces. Conclusion A vascular perfusion with 3% HES impairs the endothelial and epithelial barrier integrity as well as metabolic function of the small

  10. Oxygen dependence of cellular uptake of EF5 [2-(2-nitro-1H-imidazol-1-yl)-N-(2,2,3,3,3-pentafluoropropyl)a cet amide] : analysis of drug adducts by fluorescent antibodies vs bound radioactivity.

    PubMed

    Koch, C J; Evans, S M; Lord, E M

    1995-10-01

    The present studies were initiated to quantitate the oxygen dependence of bioreductive metabolism-induced binding of EF5, a pentafluorinated derivative of the 2-nitroimidazole, etanidazole. Two different assays were compared: first, radioactive drug incorporation into cell lysates, which provides a direct measure of drug metabolism or uptake; second, monoclonal antibody detection of cellular macromolecular adducts of EF5 after whole cell permeabilisation and fixing. The antibodies (a single clone designated ELK3-51) were conjugated with the fluorescent dye Cy3, with fluorescence determined by fluorescence microscopy and flow cytometry. For the two cell lines tested (V79 Chinese hamster fibroblasts and 9L rat glioma), the oxygen dependence of binding was found to be the same for the two techniques. Using the antibody binding technique, the fluorescence signal was highly reproducible between experiments, resistant to light or chemical bleaching and stable over time following cell or tissue staining. Flow cytometric analysis of cells from rat 9L tumours treated with EF5 in vivo or in vitro showed a distribution of fluorescent signal which was very compatible, on both a relative and absolute basis, with the in vitro results. Our results indicate that immunofluorescent techniques provide a quantitative assay for bioreductive drug adducts, and therefore may be able to measure the absolute oxygen concentration distribution in cell populations and tissues of interest. PMID:7547233

  11. Intestinal adaptation after massive intestinal resection

    PubMed Central

    Weale, A; Edwards, A; Bailey, M; Lear, P

    2005-01-01

    Patients with short bowel syndrome require long term parenteral nutrition support. However, after massive intestinal resection the intestine undergoes adaptation and nutritional autonomy may be obtained. Given that the complications of parenteral nutrition may be life threatening or result in treatment failure and the need for intestinal transplantation, a more attractive option is to wean patients off nutrition support by optimising the adaptive process. The article examines the evidence that after extensive small bowel resection adaptation occurs in humans and focuses on the factors that influence adaptation and the strategies that have been used to optimise this process. The review is based on an English language Medline search with secondary references obtained from key articles. There is evidence that adaptation occurs in humans. Adaptation is a complex process that results in response to nutrient and non-nutrient stimuli. Successful and reproducible strategies to improve adaptation remain elusive despite an abundance of experimental data. Nevertheless given the low patient survival and quality of life associated with other treatments for irreversible intestinal failure it is imperative that clinical research continues into the optimisation of the adaptation. PMID:15749794

  12. Intestinal colonization resistance

    PubMed Central

    Lawley, Trevor D; Walker, Alan W

    2013-01-01

    Dense, complex microbial communities, collectively termed the microbiota, occupy a diverse array of niches along the length of the mammalian intestinal tract. During health and in the absence of antibiotic exposure the microbiota can effectively inhibit colonization and overgrowth by invading microbes such as pathogens. This phenomenon is called ‘colonization resistance’ and is associated with a stable and diverse microbiota in tandem with a controlled lack of inflammation, and involves specific interactions between the mucosal immune system and the microbiota. Here we overview the microbial ecology of the healthy mammalian intestinal tract and highlight the microbe–microbe and microbe–host interactions that promote colonization resistance. Emerging themes highlight immunological (T helper type 17/regulatory T-cell balance), microbiota (diverse and abundant) and metabolic (short-chain fatty acid) signatures of intestinal health and colonization resistance. Intestinal pathogens use specific virulence factors or exploit antibiotic use to subvert colonization resistance for their own benefit by triggering inflammation to disrupt the harmony of the intestinal ecosystem. A holistic view that incorporates immunological and microbiological facets of the intestinal ecosystem should facilitate the development of immunomodulatory and microbe-modulatory therapies that promote intestinal homeostasis and colonization resistance. PMID:23240815

  13. Norepinephrine uptake by rat jejunum: Modulation by angiotensin II

    SciTech Connect

    Suvannapura, A.; Levens, N.R. )

    1988-02-01

    Angiotensin II (ANG II) is believed to stimulate sodium and water absorption from the small intestine by enhancing sympathetic nerve transmission. This study is designed to determine whether ANG II can enhance sympathetic neurotransmission within the small intestine by inhibition norepinephrine (NE) uptake. Intracellular NE accumulation by rat jejunum was concentration dependent and resolved into high- and low-affinity components. The high-affinity component (uptake 1) exhibited a Michaelis constant (K{sub m}) of 1.72 {mu}M and a maximum velocity (V{sub max}) of 1.19 nmol {center dot} g{sup {minus}1} {center dot} 10 min{sup {minus}1}. The low-affinity component (uptake 2) exhibited a K{sub m} of 111.1 {mu}M and a V{sub max} of 37.1 nmol {center dot} g{sup {minus}1} {center dot} 10 min{sup {minus}1}. Cocaine, an inhibitor of neuronal uptake, inhibited the intracellular accumulation of label by 80%. Treatment of animals with 6-hydroxydopamine, which depletes norepinephrine from sympathetic terminals, also attenuated NE uptake by 60%. Thus accumulation within sympathetic nerves constitutes the major form of ({sup 3}H)NE uptake into rat jejunum. ANG II inhibited intracellular ({sup 3}H)NE uptake in a concentration-dependent manner. At a dose of 1 mM, ANG II inhibited intracellular ({sup 3}H)NE accumulation by 60%. Cocaine failed to potentiate the inhibition of ({sup 3}H)NE uptake produced by ANG II. Thus ANG II appears to prevent ({sup 3}H)NE accumulation within rat jejunum by inhibiting neuronal uptake.

  14. Pediatric intestinal motility disorders

    PubMed Central

    Gfroerer, Stefan; Rolle, Udo

    2015-01-01

    Pediatric intestinal motility disorders affect many children and thus not only impose a significant impact on pediatric health care in general but also on the quality of life of the affected patient. Furthermore, some of these conditions might also have implications for adulthood. Pediatric intestinal motility disorders frequently present as chronic constipation in toddler age children. Most of these conditions are functional, meaning that constipation does not have an organic etiology, but in 5% of the cases, an underlying, clearly organic disorder can be identified. Patients with organic causes for intestinal motility disorders usually present in early infancy or even right after birth. The most striking clinical feature of children with severe intestinal motility disorders is the delayed passage of meconium in the newborn period. This sign is highly indicative of the presence of Hirschsprung disease (HD), which is the most frequent congenital disorder of intestinal motility. HD is a rare but important congenital disease and the most significant entity of pediatric intestinal motility disorders. The etiology and pathogenesis of HD have been extensively studied over the last several decades. A defect in neural crest derived cell migration has been proven as an underlying cause of HD, leading to an aganglionic distal end of the gut. Numerous basic science and clinical research related studies have been conducted to better diagnose and treat HD. Resection of the aganglionic bowel remains the gold standard for treatment of HD. Most recent studies show, at least experimentally, the possibility of a stem cell based therapy for HD. This editorial also includes rare causes of pediatric intestinal motility disorders such as hypoganglionosis, dysganglionosis, chronic intestinal pseudo-obstruction and ganglioneuromatosis in multiple endocrine metaplasia. Underlying organic pathologies are rare in pediatric intestinal motility disorders but must be recognized as early as

  15. Pediatric intestinal motility disorders.

    PubMed

    Gfroerer, Stefan; Rolle, Udo

    2015-09-01

    Pediatric intestinal motility disorders affect many children and thus not only impose a significant impact on pediatric health care in general but also on the quality of life of the affected patient. Furthermore, some of these conditions might also have implications for adulthood. Pediatric intestinal motility disorders frequently present as chronic constipation in toddler age children. Most of these conditions are functional, meaning that constipation does not have an organic etiology, but in 5% of the cases, an underlying, clearly organic disorder can be identified. Patients with organic causes for intestinal motility disorders usually present in early infancy or even right after birth. The most striking clinical feature of children with severe intestinal motility disorders is the delayed passage of meconium in the newborn period. This sign is highly indicative of the presence of Hirschsprung disease (HD), which is the most frequent congenital disorder of intestinal motility. HD is a rare but important congenital disease and the most significant entity of pediatric intestinal motility disorders. The etiology and pathogenesis of HD have been extensively studied over the last several decades. A defect in neural crest derived cell migration has been proven as an underlying cause of HD, leading to an aganglionic distal end of the gut. Numerous basic science and clinical research related studies have been conducted to better diagnose and treat HD. Resection of the aganglionic bowel remains the gold standard for treatment of HD. Most recent studies show, at least experimentally, the possibility of a stem cell based therapy for HD. This editorial also includes rare causes of pediatric intestinal motility disorders such as hypoganglionosis, dysganglionosis, chronic intestinal pseudo-obstruction and ganglioneuromatosis in multiple endocrine metaplasia. Underlying organic pathologies are rare in pediatric intestinal motility disorders but must be recognized as early as

  16. Brazilian Twin Registry: A Bright Future for Twin Studies/Twin Research: Twin Study of Alcohol Consumption and Mortality; Oxygen Uptake in Adolescent Twins/In the News: Superfecundated Twins In Vietnam; Adolescent Twin Relations; Twin and Triplet Co-Workers; A Special Twin Ultrasound; Monozygotic Twins With Different Skin Color; Identical Twin Returns from Space.

    PubMed

    Segal, Nancy L

    2016-06-01

    The establishment of the Brazilian Twin Registry for the study of genetic, social, and cultural influences on behavior is one of eleven newly funded projects in the Department of Psychology at the University of São Paulo. These 11 interrelated projects form the core of the university's Center for Applied Research on Well-Being and Human Behavior. An overview of the planned twin research and activities to date is presented. Next, two recent twin studies are reviewed, one on the relationship between alcohol consumption and mortality, and the other on factors affecting maximal oxygen uptake. Twins cited in the media include the first identified superfecundated twins in Vietnam, adolescent twin relations, twins and triplets who work together, monozygotic twins with different skin tones and a co-twin control study that addresses the effects of space travel. PMID:27121223

  17. Microbiota regulate intestinal absorption and metabolism of fatty acids in the zebrafish.

    PubMed

    Semova, Ivana; Carten, Juliana D; Stombaugh, Jesse; Mackey, Lantz C; Knight, Rob; Farber, Steven A; Rawls, John F

    2012-09-13

    Regulation of intestinal dietary fat absorption is critical to maintaining energy balance. While intestinal microbiota clearly impact the host's energy balance, their role in intestinal absorption and extraintestinal metabolism of dietary fat is less clear. Using in vivo imaging of fluorescent fatty acid (FA) analogs delivered to gnotobiotic zebrafish hosts, we reveal that microbiota stimulate FA uptake and lipid droplet (LD) formation in the intestinal epithelium and liver. Microbiota increase epithelial LD number in a diet-dependent manner. The presence of food led to the intestinal enrichment of bacteria from the phylum Firmicutes. Diet-enriched Firmicutes and their products were sufficient to increase epithelial LD number, whereas LD size was increased by other bacterial types. Thus, different members of the intestinal microbiota promote FA absorption via distinct mechanisms. Diet-induced alterations in microbiota composition might influence fat absorption, providing mechanistic insight into how microbiota-diet interactions regulate host energy balance. PMID:22980325

  18. Conditional knockout of the Slc5a6 gene in mouse intestine impairs biotin absorption

    PubMed Central

    Ghosal, Abhisek; Lambrecht, Nils; Subramanya, Sandeep B.; Kapadia, Rubina

    2013-01-01

    The Slc5a6 gene expresses a plasma membrane protein involved in the transport of the water-soluble vitamin biotin; the transporter is commonly referred to as the sodium-dependent multivitamin transporter (SMVT) because it also transports pantothenic acid and lipoic acid. The relative contribution of the SMVT system toward carrier-mediated biotin uptake in the native intestine in vivo has not been established. We used a Cre/lox technology to generate an intestine-specific (conditional) SMVT knockout (KO) mouse model to address this issue. The KO mice exhibited absence of expression of SMVT in the intestine compared with sex-matched littermates as well as the expected normal SMVT expression in other tissues. About two-thirds of the KO mice died prematurely between the age of 6 and 10 wk. Growth retardation, decreased bone density, decreased bone length, and decreased biotin status were observed in the KO mice. Microscopic analysis showed histological abnormalities in the small bowel (shortened villi, dysplasia) and cecum (chronic active inflammation, dysplasia) of the KO mice. In vivo (and in vitro) transport studies showed complete inhibition in carrier-mediated biotin uptake in the intestine of the KO mice compared with their control littermates. These studies provide the first in vivo confirmation in native intestine that SMVT is solely responsible for intestinal biotin uptake. These studies also provide evidence for a casual association between SMVT function and normal intestinal health. PMID:23104561

  19. Intestinal pseudo-obstruction

    MedlinePlus

    ... syndrome). Special diets often do not work. However, vitamin B12 and other vitamin supplements should be used for ... JM, Blackshaw LA. Small intestinal motor and sensory function and dysfunction. In: Feldman M, Friedman LS, Brandt ...

  20. Intestinal obstruction repair

    MedlinePlus

    ... organs in the body Formation of scar tissue ( adhesions ) Heart attack or stroke Infection, including the lungs, ... Saunders; 2010:chap 119. Read More Abdomen - swollen Adhesion Colostomy Cyst Intestinal obstruction Intussusception - children Large bowel ...

  1. Intestinal mucosal adaptation

    PubMed Central

    Drozdowski, Laurie; Thomson, Alan BR

    2006-01-01

    Intestinal failure is a condition characterized by malnutrition and/or dehydration as a result of the inadequate digestion and absorption of nutrients. The most common cause of intestinal failure is short bowel syndrome, which occurs when the functional gut mass is reduced below the level necessary for adequate nutrient and water absorption. This condition may be congenital, or may be acquired as a result of a massive resection of the small bowel. Following resection, the intestine is capable of adaptation in response to enteral nutrients as well as other trophic stimuli. Identifying factors that may enhance the process of intestinal adaptation is an exciting area of research with important potential clinical applications. PMID:16937429

  2. Diet, Microbiome, and the Intestinal Epithelium: An Essential Triumvirate?

    PubMed Central

    Guzman, Javier Rivera; Conlin, Victoria Susan; Jobin, Christian

    2013-01-01

    The intestinal epithelium represents a critical barrier protecting the host against diverse luminal noxious agents, as well as preventing the uncontrolled uptake of bacteria that could activate an immune response in a susceptible host. The epithelial monolayer that constitutes this barrier is regulated by a meshwork of proteins that orchestrate complex biological function such as permeability, transepithelial electrical resistance, and movement of various macromolecules. Because of its key role in maintaining host homeostasis, factors regulating barrier function have attracted sustained attention from the research community. This paper will address the role of bacteria, bacterial-derived metabolism, and the interplay of dietary factors in controlling intestinal barrier function. PMID:23586037

  3. Claudins in intestines

    PubMed Central

    Lu, Zhe; Ding, Lei; Lu, Qun; Chen, Yan-Hua

    2013-01-01

    Intestines are organs that not only digest food and absorb nutrients, but also provide a defense barrier against pathogens and noxious agents ingested. Tight junctions (TJs) are the most apical component of the junctional complex, providing one form of cell-cell adhesion in enterocytes and playing a critical role in regulating paracellular barrier permeability. Alteration of TJs leads to a number of pathophysiological diseases causing malabsorption of nutrition and intestinal structure disruption, which may even contribute to systemic organ failure. Claudins are the major structural and functional components of TJs with at least 24 members in mammals. Claudins have distinct charge-selectivity, either by tightening the paracellular pathway or functioning as paracellular channels, regulating ions and small molecules passing through the paracellular pathway. In this review, we have discussed the functions of claudin family members, their distribution and localization in the intestinal tract of mammals, their alterations in intestine-related diseases and chemicals/agents that regulate the expression and localization of claudins as well as the intestinal permeability, which provide a therapeutic view for treating intestinal diseases. PMID:24478939

  4. Vibrio vulnificus VvpE Stimulates IL-1β Production by the Hypomethylation of the IL-1β Promoter and NF-κB Activation via Lipid Raft-Dependent ANXA2 Recruitment and Reactive Oxygen Species Signaling in Intestinal Epithelial Cells.

    PubMed

    Lee, Sei-Jung; Jung, Young Hyun; Song, Eun Ju; Jang, Kyung Ku; Choi, Sang Ho; Han, Ho Jae

    2015-09-01

    An inflammatory response is a hallmark of necrosis evoked by bacterial pathogens. Vibrio vulnificus, VvpE, is an elastase that is responsible for tissue necrosis and inflammation; however, the molecular mechanism by which it regulates host cell death has not been characterized. In the present study, we investigate the cellular mechanism of VvpE with regard to host cell death and the inflammatory response of human intestinal epithelial (INT-407) cells. The recombinant protein (r)VvpE (50 pg/ml) caused cytotoxicity mainly via necrosis coupled with IL-1β production. The necrotic cell death induced by rVvpE is highly susceptible to the knockdown of annexin A (ANXA)2 and the sequestration of membrane cholesterol. We found that rVvpE induces the recruitment of NADPH oxidase 2 and neutrophil cytosolic factor 1 into membrane lipid rafts coupled with ANXA2 to facilitate the production of reactive oxygen species (ROS). The bacterial signaling of rVvpE through ROS production is uniquely mediated by the phosphorylation of redox-sensitive transcription factor NF-κB. The silencing of NF-κB inhibited IL-1β production during necrosis. rVvpE induced hypomethylation and region-specific transcriptional occupancy by NF-κB in the IL-1β promoter and has the ability to induce pyroptosis via NOD-, LRR-, and pyrin domain-containing 3 inflammasome. In a mouse model of V. vulnificus infection, the mutation of the vvpE gene from V. vulnificus negated the proinflammatory responses and maintained the physiological levels of the proliferation and migration of enterocytes. These results demonstrate that VvpE induces the hypomethylation of the IL-1β promoter and the transcriptional regulation of NF-κB through lipid raft-dependent ANXA2 recruitment and ROS signaling to promote IL-1β production in intestinal epithelial cells. PMID:26223656

  5. Uptake As Language Awareness.

    ERIC Educational Resources Information Center

    Ellis, Rod

    1995-01-01

    Investigates the sincerity and validity of uptake as a measure of language learning by comparing the words students report they have learned after completing a listening task with the words they score correctly on a translation test. Results indicate that whereas uptake may have construct validity, its concurrent validity is uncertain. (16…

  6. Modeling Oxygen Transport in the Human Placenta

    NASA Astrophysics Data System (ADS)

    Serov, Alexander; Filoche, Marcel; Salafia, Carolyn; Grebenkov, Denis

    Efficient functioning of the human placenta is crucial for the favorable pregnancy outcome. We construct a 3D model of oxygen transport in the placenta based on its histological cross-sections. The model accounts for both diffusion and convention of oxygen in the intervillous space and allows one to estimate oxygen uptake of a placentone. We demonstrate the existence of an optimal villi density maximizing the uptake and explain it as a trade-off between the incoming oxygen flow and the absorbing villous surface. Calculations performed for arbitrary shapes of fetal villi show that only two geometrical characteristics - villi density and the effective villi radius - are required to predict fetal oxygen uptake. Two combinations of physiological parameters that determine oxygen uptake are also identified: maximal oxygen inflow of a placentone and the Damköhler number. An automatic image analysis method is developed and applied to 22 healthy placental cross-sections demonstrating that villi density of a healthy human placenta lies within 10% of the optimal value, while overall geometry efficiency is rather low (around 30-40%). In a perspective, the model can constitute the base of a reliable tool of post partum oxygen exchange efficiency assessment in the human placenta. Also affiliated with Department of Chemistry and Biochemistry, UCLA, Los Angeles, CA 90095, USA.

  7. Stress modulates intestinal secretory immunoglobulin A

    PubMed Central

    Campos-Rodríguez, Rafael; Godínez-Victoria, Marycarmen; Abarca-Rojano, Edgar; Pacheco-Yépez, Judith; Reyna-Garfias, Humberto; Barbosa-Cabrera, Reyna Elizabeth; Drago-Serrano, Maria Elisa

    2013-01-01

    Stress is a response of the central nervous system to environmental stimuli perceived as a threat to homeostasis. The stress response triggers the generation of neurotransmitters and hormones from the hypothalamus pituitary adrenal axis, sympathetic axis and brain gut axis, and in this way modulates the intestinal immune system. The effects of psychological stress on intestinal immunity have been investigated mostly with the restraint/immobilization rodent model, resulting in an up or down modulation of SIgA levels depending on the intensity and time of exposure to stress. SIgA is a protein complex formed by dimeric (dIgA) or polymeric IgA (pIgA) and the secretory component (SC), a peptide derived from the polymeric immunoglobulin receptor (pIgR). The latter receptor is a transmembrane protein expressed on the basolateral side of gut epithelial cells, where it uptakes dIgA or pIgA released by plasma cells in the lamina propria. As a result, the IgA-pIgR complex is formed and transported by vesicles to the apical side of epithelial cells. pIgR is then cleaved to release SIgA into the luminal secretions of gut. Down modulation of SIgA associated with stress can have negative repercussions on intestinal function and integrity. This can take the form of increased adhesion of pathogenic agents to the intestinal epithelium and/or an altered balance of inflammation leading to greater intestinal permeability. Most studies on the molecular and biochemical mechanisms involved in the stress response have focused on systemic immunity. The present review analyzes the impact of stress (mostly by restraint/immobilization, but also with mention of other models) on the generation of SIgA, pIgR and other humoral and cellular components involved in the intestinal immune response. Insights into these mechanisms could lead to better therapies for protecting against pathogenic agents and avoiding epithelial tissue damage by modulating intestinal inflammation. PMID:24348350

  8. [Intestinal obstruction during pregnancy].

    PubMed

    Stukan, Maciej; Kruszewski Wiesław, Janusz; Dudziak, Mirosław; Kopiejć, Arkadiusz; Preis, Krzysztof

    2013-02-01

    This is a review of literature concerning intestinal obstruction in pregnant women. Approximately 50-90% and 30% of pregnant women, respectively suffer from nausea and vomiting, mostly during the first trimester. There is also increased risk of constipation. During the perioperative period, the administration of tocolytics should be considered only in women showing symptoms of a threatening premature delivery. Intensive hydration should be ordered to sustain uterine blood flow. The incidence of intestinal obstruction during pregnancy is estimated at 1:1500-1:66431 pregnancies and is diagnosed in II and III trimester in most cases. However, it can also occur in the I trimester (6%) or puerperium. Symptoms of intestinal obstruction in pregnancy include: abdominal pains (98%), vomiting (82%), constipation (30%). Abdominal tenderness on palpation is found in 71% and abnormal peristalsis in 55% of cases. The most common imaging examination in the diagnosis of intestinal obstruction is the abdominal X-ray. However ionizing radiation may have a harmful effect on the fetus, especially during the first trimester. X-ray is positive for intestinal obstruction in 82% of pregnant women. Ultrasonography and magnetic resonance imaging are considered safe and applicable during pregnancy. Intestinal obstruction in pregnant women is mostly caused by: adhesions (54.6%), intestinal torsion (25%), colorectal carcinoma (3.7%), hernia (1.4%), appendicitis (0.5%) and others (10%). Adhesive obstruction occurs more frequently in advanced pregnancy (6% - I trimester 28% - II trimester; 45% - III trimester 21% - puerperium). Treatment should begin with conservative procedures. Surgical treatment may be necessary in cases where the pain turns from recurrent into continuous, with tachycardia, pyrexia and a positive Blumberg sign. If symptoms of fetal anoxia are observed, a C-section should be carried out before surgical intervention. The extent of surgical intervention depends on the

  9. The intestine is a blender

    NASA Astrophysics Data System (ADS)

    Yang, Patricia; Lamarca, Morgan; Kravets, Victoria; Hu, David

    According to the U.S. Department of Health and Human Services, digestive disease affects 60 to 70 million people and costs over 140 billion annually. Despite the significance of the gastrointestinal tract to human health, the physics of digestion remains poorly understood. In this study, we ask a simple question: what sets the frequency of intestinal contractions? We measure the frequency of intestinal contractions in rats, as a function of distance down the intestine. We find that intestines Contract radially ten times faster than longitudinally. This motion promotes mixing and, in turn, absorption of food products by the intestinal wall. We calculate viscous dissipation in the intestinal fluid to rationalize the relationship between frequency of intestinal contraction and the viscosity of the intestinal contents. Our findings may help to understand the evolution of the intestine as an ideal mixer.

  10. The intestine is a blender

    NASA Astrophysics Data System (ADS)

    Yang, Patricia; Lamarca, Morgan; Hu, David

    2015-11-01

    According to the U.S. Department of Health and Human Services, digestive disease affects 60 to 70 million people and costs over 140 billion annually. Despite the significance of the gastrointestinal tract to human health, the physics of digestion remains poorly understood. In this study, we ask a simple question: what sets the frequency of intestinal contractions? We measure the frequency of intestinal contractions in rats, as a function of distance down the intestine. We find that intestines contract radially ten times faster than longitudinally. This motion promotes mixing and, in turn, absorption of food products by the intestinal wall. We calculate viscous dissipation in the intestinal fluid to rationalize the relationship between frequency of intestinal contraction and the viscosity of the intestinal contents. Our findings may help to understand the evolution of the intestine as an ideal mixer.

  11. Rac1 drives intestinal stem cell proliferation and regeneration

    PubMed Central

    Myant, Kevin B; Scopelliti, Alessandro; Haque, Sara; Vidal, Marcos; Sansom, Owen J; Cordero, Julia B

    2013-01-01

    Adult stem cells are responsible for maintaining the balance between cell proliferation and differentiation within self-renewing tissues. The molecular and cellular mechanisms mediating such balance are poorly understood. The production of reactive oxygen species (ROS) has emerged as an important mediator of stem cell homeostasis in various systems. Our recent work demonstrates that Rac1-dependent ROS production mediates intestinal stem cell (ISC) proliferation in mouse models of colorectal cancer (CRC). Here, we use the adult Drosophila midgut and the mouse small intestine to directly address the role of Rac1 in ISC proliferation and tissue regeneration in response to damage. Our results demonstrate that Rac1 is necessary and sufficient to drive ISC proliferation and regeneration in an ROS-dependent manner. Our data point to an evolutionarily conserved role of Rac1 in intestinal homeostasis and highlight the value of combining work in the mammalian and Drosophila intestine as paradigms to study stem cell biology. PMID:23974108

  12. Dietary cholesterol directly induces acute inflammasome-dependent intestinal inflammation.

    PubMed

    Progatzky, Fränze; Sangha, Navjyot J; Yoshida, Nagisa; McBrien, Marie; Cheung, Jackie; Shia, Alice; Scott, James; Marchesi, Julian R; Lamb, Jonathan R; Bugeon, Laurence; Dallman, Margaret J

    2014-01-01

    Prolonged ingestion of a cholesterol- or saturated fatty acid-enriched diet induces chronic, often systemic, auto-inflammatory responses resulting in significant health problems worldwide. In vivo information regarding the local and direct inflammatory effect of these dietary components in the intestine and, in particular, on the intestinal epithelium is lacking. Here we report that both mice and zebrafish exposed to high-fat (HFDs) or high-cholesterol (HCDs) diets develop acute innate inflammatory responses within hours, reflected in the localized interleukin-1β-dependent accumulation of myeloid cells in the intestine. Acute HCD-induced intestinal inflammation is dependent on cholesterol uptake via Niemann-Pick C1-like 1 and inflammasome activation involving apoptosis-associated Speck-like protein containing a caspase recruitment domain, which leads to Caspase-1 activity in intestinal epithelial cells. Extended exposure to HCD results in localized, inflammation-dependent, functional dysregulation as well as systemic pathologies. Our model suggests that dietary cholesterol initiates intestinal inflammation in epithelial cells. PMID:25536194

  13. Dietary cholesterol directly induces acute inflammasome-dependent intestinal inflammation

    PubMed Central

    Progatzky, Fränze; Sangha, Navjyot J.; Yoshida, Nagisa; McBrien, Marie; Cheung, Jackie; Shia, Alice; Scott, James; Marchesi, Julian R.; Lamb, Jonathan R.; Bugeon, Laurence; Dallman, Margaret J.

    2014-01-01

    Prolonged ingestion of a cholesterol- or saturated fatty acid-enriched diet induces chronic, often systemic, auto-inflammatory responses resulting in significant health problems worldwide. In vivo information regarding the local and direct inflammatory effect of these dietary components in the intestine and, in particular, on the intestinal epithelium is lacking. Here we report that both mice and zebrafish exposed to high-fat (HFDs) or high-cholesterol (HCDs) diets develop acute innate inflammatory responses within hours, reflected in the localized interleukin-1β-dependent accumulation of myeloid cells in the intestine. Acute HCD-induced intestinal inflammation is dependent on cholesterol uptake via Niemann-Pick C1-like 1 and inflammasome activation involving apoptosis-associated Speck-like protein containing a caspase recruitment domain, which leads to Caspase-1 activity in intestinal epithelial cells. Extended exposure to HCD results in localized, inflammation-dependent, functional dysregulation as well as systemic pathologies. Our model suggests that dietary cholesterol initiates intestinal inflammation in epithelial cells. PMID:25536194

  14. Wastewater treatment with zero dissolved oxygen

    SciTech Connect

    Hirl, P.J.

    1998-07-01

    Many wastewater treatment plants operate their biological reactors inefficiently because the aeration is not adjusted so that the oxygen supply rate equals the microbial oxygen demand in real times. Tapered aeration systems vary aeration based on the oxygen demand profile but these systems are static. Dynamic oxygen control systems have been successful but do not operate at low dissolved oxygen concentrations. The purpose of the research described is to develop a control system and reactor operating strategies to dynamically change the aeration rate to match the oxygen uptake rate while maintaining the dissolve oxygen concentration less than 0.5 mg/L. Though, low dissolved oxygen operation can reduce the rate of carbon degradation and/or promote filamentous bulking, it also maximizes the oxygen transfer rate and can promote simultaneous nitrification and denitrification. Development and testing of a control system and operating strategies at the bench scale is in progress.

  15. Claudin-2 as a mediator of leaky gut barrier during intestinal inflammation.

    PubMed

    Luettig, J; Rosenthal, R; Barmeyer, C; Schulzke, J D

    2015-01-01

    The epithelial tight junction determines the paracellular water and ion movement in the intestine and also prevents uptake of larger molecules, including antigens, in an uncontrolled manner. Claudin-2, one of the 27 mammalian claudins regulating that barrier function, forms a paracellular channel for small cations and water. It is typically expressed in leaky epithelia like proximal nephron and small intestine and provides a major pathway for the paracellular transport of sodium, potassium, and fluid. In intestinal inflammation (Crohn's disease, ulcerative colitis), immune-mediated diseases (celiac disease), and infections (HIV enteropathy), claudin-2 is upregulated in small and large intestine and contributes to diarrhea via a leak flux mechanism. In parallel to that upregulation, other epithelial and tight junctional features are altered and the luminal uptake of antigenic macromolecules is enhanced, for which claudin-2 may be partially responsible through induction of tight junction strand discontinuities. PMID:25838982

  16. Noncanonical role of transferrin receptor 1 is essential for intestinal homeostasis

    PubMed Central

    Chen, Alan C.; Donovan, Adriana; Ned-Sykes, Renee; Andrews, Nancy C.

    2015-01-01

    Transferrin receptor 1 (Tfr1) facilitates cellular iron uptake through receptor-mediated endocytosis of iron-loaded transferrin. It is expressed in the intestinal epithelium but not involved in dietary iron absorption. To investigate its role, we inactivated the Tfr1 gene selectively in murine intestinal epithelial cells. The mutant mice had severe disruption of the epithelial barrier and early death. There was impaired proliferation of intestinal epithelial cell progenitors, aberrant lipid handling, increased mRNA expression of stem cell markers, and striking induction of many genes associated with epithelial-to-mesenchymal transition. Administration of parenteral iron did not improve the phenotype. Surprisingly, however, enforced expression of a mutant allele of Tfr1 that is unable to serve as a receptor for iron-loaded transferrin appeared to fully rescue most animals. Our results implicate Tfr1 in homeostatic maintenance of the intestinal epithelium, acting through a role that is independent of its iron-uptake function. PMID:26324903

  17. Epithelial tight junctions in intestinal inflammation.

    PubMed

    Schulzke, Joerg D; Ploeger, Svenja; Amasheh, Maren; Fromm, Anja; Zeissig, Sebastian; Troeger, Hanno; Richter, Jan; Bojarski, Christian; Schumann, Michael; Fromm, Michael

    2009-05-01

    The epithelium in inflamed intestinal segments of patients with Crohn's disease is characterized by a reduction of tight junction strands, strand breaks, and alterations of tight junction protein content and composition. In ulcerative colitis, epithelial leaks appear early due to micro-erosions resulting from upregulated epithelial apoptosis and in addition to a prominent increase of claudin-2. Th1-cytokine effects by interferon-gamma in combination with TNFalpha are important for epithelial damage in Crohn's disease, while interleukin-13 (IL-13) is the key effector cytokine in ulcerative colitis stimulating apoptosis and upregulation of claudin-2 expression. Focal lesions caused by apoptotic epithelial cells contribute to barrier disturbance in IBD by their own conductivity and by confluence toward apoptotic foci or erosions. Another type of intestinal barrier defect can arise from alpha-hemolysin harboring E. coli strains among the physiological flora, which can gain pathologic relevance in combination with proinflammatory cytokines under inflammatory conditions. On the other hand, intestinal barrier impairment can also result from transcellular antigen translocation via an initial endocytotic uptake into early endosomes, and this is intensified by proinflammatory cytokines as interferon-gamma and may thus play a relevant role in the onset of IBD. Taken together, barrier defects contribute to diarrhea by a leak flux mechanism (e.g., in IBD) and can cause mucosal inflammation by luminal antigen uptake. Immune regulation of epithelial functions by cytokines may cause barrier dysfunction not only by tight junction impairments but also by apoptotic leaks, transcytotic mechanisms, and mucosal gross lesions. PMID:19538319

  18. Defective small intestinal anion secretion, dipeptide absorption, and intestinal failure in suckling NBCe1-deficient mice.

    PubMed

    Yu, Qin; Liu, Xuemei; Liu, Yongjian; Riederer, Brigitte; Li, Taolang; Tian, De-An; Tuo, Biguang; Shull, Gary; Seidler, Ursula

    2016-08-01

    The electrogenic Na(+)HCO3 (-) cotransporter NBCe1 (Slc4a4) is strongly expressed in the basolateral enterocyte membrane in a villous/surface predominant fashion. In order to better understand its physiological function in the intestine, isolated mucosae in miniaturized Ussing chambers and microdissected intestinal villi or crypts loaded with the fluorescent pH-indicator BCECF were studied from the duodenum, jejunum, and colon of 14- to 17-days-old slc4a4-deficient (KO) and WT mice. NBCe1 was active in the basal state in all intestinal segments under study, most likely to compensate for acid loads imposed upon the enterocytes. Upregulation of other basolateral base uptake mechanism occurs, but in a segment-specific fashion. Loss of NBCe1 resulted in severely impaired Cl(-) and fluid secretory response, but not HCO3 (-) secretory response to agonist stimulation. In addition, NBCe1 was found to be active during transport processes that load the surface enterocytes with acid, such as Slc26a3 (DRA)-mediated luminal Cl(-)/HCO3 (-) exchange or PEPT1-mediated H(+)/dipeptide uptake. Possibly because of the high energy demand for hyperventilation in conjunction with the fluid secretory and nutrient absorptive defects and the relative scarcity of compensatory mechanisms, NBCe1-deficient mice developed progressive jejunal failure, worsening of metabolic acidosis, and death in the third week of life. Our data suggest that the electrogenic influx of base via NBCe1 maintains enterocyte anion homeostasis and pHi control. Its loss impairs small intestinal Cl(-) and fluid secretion as well as the neutralization of acid loads imposed on the enterocytes during nutrient and electrolyte absorption. PMID:27228994

  19. Oxygen Therapy

    MedlinePlus

    ... 85-95% pure oxygen. The concentrator runs on electricity or a battery. A concentrator for home usually ... systems deliver 100% oxygen, and do not require electricity. A small canister can be filled from the ...

  20. Oxygen analyzer

    DOEpatents

    Benner, William H.

    1986-01-01

    An oxygen analyzer which identifies and classifies microgram quantities of oxygen in ambient particulate matter and for quantitating organic oxygen in solvent extracts of ambient particulate matter. A sample is pyrolyzed in oxygen-free nitrogen gas (N.sub.2), and the resulting oxygen quantitatively converted to carbon monoxide (CO) by contact with hot granular carbon (C). Two analysis modes are made possible: (1) rapid determination of total pyrolyzable oxygen obtained by decomposing the sample at 1135.degree. C., or (2) temperature-programmed oxygen thermal analysis obtained by heating the sample from room temperature to 1135.degree. C. as a function of time. The analyzer basically comprises a pyrolysis tube containing a bed of granular carbon under N.sub.2, ovens used to heat the carbon and/or decompose the sample, and a non-dispersive infrared CO detector coupled to a mini-computer to quantitate oxygen in the decomposition products and control oven heating.

  1. Intestinal and multivisceral transplantation

    PubMed Central

    Meira, Sérgio Paiva; Guardia, Bianca Della; Evangelista, Andréia Silva; Matielo, Celso Eduardo Lourenço; Neves, Douglas Bastos; Pandullo, Fernando Luis; Felga, Guilherme Eduardo Gonçalves; Alves, Jefferson André da Silva; Curvelo, Lilian Amorim; Diaz, Luiz Gustavo Guedes; Rusi, Marcela Balbo; Viveiros, Marcelo de Melo; de Almeida, Marcio Dias; Epstein, Marina Gabrielle; Pedroso, Pamella Tung; Salvalaggio, Paolo; Meirelles, Roberto Ferreira; Rocco, Rodrigo Andrey; de Almeida, Samira Scalso; de Rezende, Marcelo Bruno

    2015-01-01

    Intestinal transplantation has shown exceptional growth over the past 10 years. At the end of the 1990’s, intestinal transplantation moved out of the experimental realm to become a routine practice in treating patients with severe complications related to total parenteral nutrition and intestinal failure. In the last years, several centers reported an increasing improvement in survival outcomes (about 80%), during the first 12 months after surgery, but long-term survival is still a challenge. Several advances led to clinical application of transplants. Immunosuppression involved in intestinal and multivisceral transplantation was the biggest gain for this procedure in the past decade due to tacrolimus, and new inducing drugs, mono- and polyclonal anti-lymphocyte antibodies. Despite the advancement of rigid immunosuppression protocols, rejection is still very frequent in the first 12 months, and can result in long-term graft loss. The future of intestinal transplantation and multivisceral transplantation appears promising. The major challenge is early recognition of acute rejection in order to prevent graft loss, opportunistic infections associated to complications, post-transplant lymphoproliferative disease and graft versus host disease; and consequently, improve results in the long run. PMID:25993080

  2. Selected Phytochemicals and Culinary Plant Extracts Inhibit Fructose Uptake in Caco-2 Cells.

    PubMed

    Lee, Yurim; Lim, Yeni; Kwon, Oran

    2015-01-01

    This study compared the ability of nine culinary plant extracts containing a wide array of phytochemicals to inhibit fructose uptake and then explored the involvement of intestinal fructose transporters and phytochemicals for selected samples. The chemical signature was characterized by high performance liquid chromatography with mass spectrometry. Inhibition of [(14)C]-fructose uptake was tested by using human intestinal Caco-2 cells. Then, the relative contribution of the two apical-facing intestinal fructose transporters, GLUT2 and GLUT5, and the signature components for fructose uptake inhibition was confirmed in naive, phloretin-treated and forskolin-treated Caco-2 cells. HPLC/MS analysis of the chemical signature revealed that guava leaf contained quercetin and catechin, and turmeric contained curcumin, bisdemethoxycurcumin and dimethoxycurcumin. Similar inhibition of fructose uptake (by ~50%) was observed with guava leaf and turmeric in Caco-2 cells, but with a higher contribution of GLUT2 for turmeric and that of GLUT5 for guava leaf. The data suggested that, in turmeric, demethoxycurcumin specifically contributed to GLUT2-mediated fructose uptake inhibition, and curcumin did the same to GLUT5-mediated fructose uptake inhibition, but GLUT2 inhibition was more potent. By contrast, in guava leaf, catechin specifically contributed to GLUT5-mediated fructose uptake inhibition, and quercetin affected both GLUT5- and GLUT2-mediated fructose uptake inhibition, resulting in the higher contribution of GLUT5. These results suggest that demethoxycurcumin is an important contributor to GLUT2-mediated fructose uptake inhibition for turmeric extract, and catechin is the same to GLUT5-mediated fructose uptake inhibition for guava leaf extract. Quercetin, curcumin and bisdemethoxycurcumin contributed to both GLUT5- and GLUT2-mediated fructose uptake inhibition, but the contribution to GLUT5 inhibition was higher than the contribution to GLUT2 inhibition. PMID:26393568

  3. Inhibition of Intestinal Thiamin Transport in Rat Model of Sepsis

    PubMed Central

    Sassoon, Catherine S.; Zhu, Ercheng; Fang, Liwei; Subramanian, Veedamali S.; Said, Hamid M.

    2016-01-01

    Objective Thiamin deficiency is highly prevalent in patients with sepsis, but the mechanism by which sepsis induces thiamin deficiency is unknown. This study aimed to determine the influence of various severity of sepsis on carrier-mediated intestinal thiamin uptake, level of expressions of thiamin transporters (thiamin transporter-1 (THTR-1) and thiamin transporter-2 (THTR-2)), and mitochondrial thiamin pyrophosphate transporter (MTPPT). Design Randomized, controlled study Setting Research laboratory at a Veterans Affairs Medical Center Subjects Twenty-four Sprague-Dawley rats were randomized into controls, mild, moderate and severe sepsis with equal number of animals in each group. Measurements and Main Results Sepsis was induced by cecal ligation and puncture with the cecum ligated below the cecal valve at 25 %, 50 % and 75 % of cecal length, defined as severe, moderate and mild sepsis, respectively. Control animals underwent laparotomy only. After 2 days of induced sepsis, carrier-mediated intestinal thiamin uptake was measured using [3H]thiamin. Expressions of THTR-1, THTR-2, and MTPPT proteins and mRNA were measured. Proinflammatory cytokines (IL-1β and IL-6), and adenosine triphosphate (ATP) were also measured. Sepsis inhibited [3H]thiamin uptake and the inhibition was a function of sepsis severity. Both cell membranes thiamin transporters and MTPPT expression levels were suppressed; also levels of ATP in the intestine of animals with moderate and severe sepsis were significantly lower than that of sham operated controls. Conclusions For the first time we demonstrated that sepsis inhibited carrier-mediated intestinal thiamin uptake as a function of sepsis severity, suppressed thiamin transporters and MTPPT, leading to ATP depletion. PMID:27065466

  4. [Small intestine bacterial overgrowth].

    PubMed

    Leung Ki, E L; Roduit, J; Delarive, J; Guyot, J; Michetti, P; Dorta, G

    2010-01-27

    Small intestine bacterial overgrowth (SIBO) is a condition characterised by nutrient malabsorption and excessive bacteria in the small intestine. It typically presents with diarrhea, flatulence and a syndrome of malabsorption (steatorrhea, macrocytic anemia). However, it may be asymptomatic in the eldery. A high index of suspicion is necessary in order to differentiate SIBO from other similar presenting disorders such as coeliac disease, lactose intolerance or the irritable bowel syndrome. A search for predisposing factor is thus necessary. These factors may be anatomical (stenosis, blind loop), or functional (intestinal hypomotility, achlorydria). The hydrogen breath test is the most frequently used diagnostic test although it lacks standardisation. The treatment of SIBO consists of eliminating predisposing factors and broad-spectrum antibiotic therapy. PMID:20214190

  5. Small Intestinal Infections.

    PubMed

    Munot, Khushboo; Kotler, Donald P

    2016-06-01

    Small intestinal infections are extremely common worldwide. They may be bacterial, viral, or parasitic in etiology. Most are foodborne or waterborne, with specific etiologies differing by region and with diverse pathophysiologies. Very young, very old, and immune-deficient individuals are the most vulnerable to morbidity or mortality from small intestinal infections. There have been significant advances in diagnostic sophistication with the development and early application of molecular diagnostic assays, though these tests have not become mainstream. The lack of rapid diagnoses combined with the self-limited nature of small intestinal infections has hampered the development of specific and effective treatments other than oral rehydration. Antibiotics are not indicated in the absence of an etiologic diagnosis, and not at all in the case of some infections. PMID:27168147

  6. How Is Small Intestine Adenocarcinoma Staged?

    MedlinePlus

    ... small intestine adenocarcinoma, by stage How is small intestine adenocarcinoma staged? Staging is a process that tells ... distant m etastasis (M). T categories for small intestine adenocarcinoma T categories of small intestine cancer describe ...

  7. Radioactive iodine uptake

    MedlinePlus

    ... uptake may be due to: Factitious hyperthyroidism Iodine overload Subacute thyroiditis Silent (or painless) thyroiditis Amiodarone Risks ... to achieve this important distinction for online health information and services. Learn more about A.D.A. ...

  8. Assessment of intestinal malabsorption.

    PubMed

    Nikaki, K; Gupte, G L

    2016-04-01

    Significant efforts have been made in the last decade to either standardize the available tests for intestinal malabsorption or to develop new, more simple and reliable techniques. The quest is still on and, unfortunately, clinical practice has not dramatically changed. The investigation of intestinal malabsorption is directed by the patient's history and baseline tests. Endoscopy and small bowel biopsies play a major role although non-invasive tests are favored and often performed early on the diagnostic algorithm, especially in paediatric and fragile elderly patients. The current clinically available methods and research tools are summarized in this review article. PMID:27086887

  9. Small Intestinal Bacterial Overgrowth

    PubMed Central

    Dukowicz, Andrew C.; Levine, Gary M.

    2007-01-01

    Small intestinal bacterial overgrowth (SIBO), defined as excessive bacteria in the small intestine, remains a poorly understood disease. Initially thought to occur in only a small number of patients, it is now apparent that this disorder is more prevalent than previously thought. Patients with SIBO vary in presentation, from being only mildly symptomatic to suffering from chronic diarrhea, weight loss, and malabsorption. A number of diagnostic tests are currently available, although the optimal treatment regimen remains elusive. Recently there has been renewed interest in SIBO and its putative association with irritable bowel syndrome. In this comprehensive review, we will discuss the epidemiology, pathogenesis, clinical manifestations, diagnosis, and treatment of SIBO. PMID:21960820

  10. Small intestine contrast injection (image)

    MedlinePlus

    ... and throat, through the stomach into the small intestine. When in place, contrast dye is introduced and ... means of demonstrating whether or not the small intestine is normal when abnormality is suspected.

  11. Small intestine aspirate and culture

    MedlinePlus

    ... ency/article/003731.htm Small intestine aspirate and culture To use the sharing features on this page, please enable JavaScript. Small intestine aspirate and culture is a lab test to check for infection ...

  12. A PHYSIOLOGICALLY BASED TOXICOKINETIC MODEL FOR DIETARY UPTAKE OF HYDROPHOBIC ORGANIC COMPOUNDS BY FISH: I. FEEDING STUDIES WITH 2,2',5,5'-TETRACHLOROBIPHENYL

    EPA Science Inventory

    A physiologically-based toxicokinetic (PBTK) model was developed to describe dietary uptake of hydrophobic organic compounds by fish. The gastrointestinal (GI) tract was modeled using four compartments corresponding to the stomach, pyloric ceca, upper intestine, and lower intesti...

  13. Oxygen analyzer

    DOEpatents

    Benner, W.H.

    1984-05-08

    An oxygen analyzer which identifies and classifies microgram quantities of oxygen in ambient particulate matter and for quantitating organic oxygen in solvent extracts of ambient particulate matter. A sample is pyrolyzed in oxygen-free nitrogen gas (N/sub 2/), and the resulting oxygen quantitatively converted to carbon monoxide (CO) by contact with hot granular carbon (C). Two analysis modes are made possible: (1) rapid determination of total pyrolyzable obtained by decomposing the sample at 1135/sup 0/C, or (2) temperature-programmed oxygen thermal analysis obtained by heating the sample from room temperature to 1135/sup 0/C as a function of time. The analyzer basically comprises a pyrolysis tube containing a bed of granular carbon under N/sub 2/, ovens used to heat the carbon and/or decompose the sample, and a non-dispersive infrared CO detector coupled to a mini-computer to quantitate oxygen in the decomposition products and control oven heating.

  14. Case-Based Learning of Blood Oxygen Transport

    ERIC Educational Resources Information Center

    Cliff, William H.

    2006-01-01

    A case study about carbon monoxide poisoning was used help students gain a greater understanding of the physiology of oxygen transport by the blood. A review of student answers to the case questions showed that students can use the oxygen-hemoglobin dissociation curve to make meaningful determinations of oxygen uptake and delivery. However, the…

  15. Involvement of Concentrative Nucleoside Transporter 1 in Intestinal Absorption of Trifluridine Using Human Small Intestinal Epithelial Cells.

    PubMed

    Takahashi, Koichi; Yoshisue, Kunihiro; Chiba, Masato; Nakanishi, Takeo; Tamai, Ikumi

    2015-09-01

    TAS-102, which is effective for refractory metastatic colorectal cancer, is a combination drug of anticancer trifluridine (FTD; which is derived from pyrimidine nucleoside) and FTD-metabolizing enzyme inhibitor tipiracil hydrochloride (TPI) at a molecular ratio of 1:0.5. To evaluate the intestinal absorption mechanism of FTD, the uptake and transcellular transport of FTD by human small intestinal epithelial cell (HIEC) monolayer as a model of human intestinal epithelial cells was investigated. The uptake and membrane permeability of FTD by HIEC monolayers were saturable, Na(+) -dependent, and inhibited by nucleosides. These transport characteristics are mostly comparable with those of concentrative nucleoside transporters (CNTs). Moreover, the uptake of FTD by CNT1-expressing Xenopus oocytes was the highest among human CNT transporters. The obtained Km and Vmax values of FTD by CNT1 were 69.0 μM and 516 pmol/oocyte/30 min, respectively. The transcellular transport of FTD by Caco-2 cells, where CNT1 is heterologously expressed, from apical to basolateral side was greater than that by Mock cells. In conclusion, these results demonstrated that FTD exhibits high oral absorption by the contribution of human CNT1. PMID:25900515

  16. Intestinal volvulus in cetaceans.

    PubMed

    Begeman, L; St Leger, J A; Blyde, D J; Jauniaux, T P; Lair, S; Lovewell, G; Raverty, S; Seibel, H; Siebert, U; Staggs, S L; Martelli, P; Keesler, R I

    2013-07-01

    Intestinal volvulus was recognized as the cause of death in 18 cetaceans, including 8 species of toothed whales (suborder Odontoceti). Cases originated from 11 institutions from around the world and included both captive (n = 9) and free-ranging (n = 9) animals. When the clinical history was available (n = 9), animals consistently demonstrated acute dullness 1 to 5 days prior to death. In 3 of these animals (33%), there was a history of chronic gastrointestinal illness. The pathological findings were similar to those described in other animal species and humans, and consisted of intestinal volvulus and a well-demarcated segment of distended, congested, and edematous intestine with gas and bloody fluid contents. Associated lesions included congested and edematous mesentery and mesenteric lymph nodes, and often serofibrinous or hemorrhagic abdominal effusion. The volvulus involved the cranial part of the intestines in 85% (11 of 13). Potential predisposing causes were recognized in most cases (13 of 18, 72%) but were variable. Further studies investigating predisposing factors are necessary to help prevent occurrence and enhance early clinical diagnosis and management of the condition. PMID:23150643

  17. Congenital intestinal atresia.

    PubMed

    Davenport, M; Bianchi, A

    1990-09-01

    Surgery for infants with intestinal atresia has evolved along with the development of specialized neonatal surgical units. This once fatal condition now carries a better than 85% chance of survival and an excellent long-term prognosis. Recent advances in bowel preservation techniques have reduced morbidity and improved gut function in both the long and the short term. PMID:2257399

  18. Small Intestine Cancer Treatment

    MedlinePlus

    ... small intestine cancer include unexplained weight loss and abdominal pain. These and other signs and symptoms may be ... doctor if you have any of the following: Pain or cramps in the middle of the abdomen. Weight loss with no known reason. A lump ...

  19. Simulated gastrointestinal digestion, intestinal permeation and plasma protein interaction of white, green, and black tea polyphenols.

    PubMed

    Tenore, Gian Carlo; Campiglia, Pietro; Giannetti, Daniela; Novellino, Ettore

    2015-02-15

    The gastrointestinal digestion, intestinal permeation, and plasma protein interaction of polyphenols from a single tea cultivar at different stages of processing (white, green, and black teas) were simulated. The salivary phase contained 74.8-99.5% of native polyphenols, suggesting potential bioavailability of significant amounts of antioxidants through the oral mucosal epithelium that might be gastric sensitive and/or poorly absorbed in the intestine. White tea had the highest content and provided the best intestinal bioaccessibility and bioavailability for catechins. Since most of native catechins were not absorbed, they were expected to accumulate in the intestinal lumen where a potential inhibition capacity of cellular glucose and cholesterol uptake was assumed. The permeated catechins (approximately, 2-15% of intestinal levels) significantly bound (about 37%) to plasma HDLs, suggesting a major role in cholesterol metabolism. White tea and its potential nutraceuticals could be effective in the regulation of plasma glucose and cholesterol levels. PMID:25236233

  20. The gut wall provides an effective barrier against nanoparticle uptake

    PubMed Central

    Sinnecker, Heike; Krause, Thorsten; Koelling, Sabine; Lautenschläger, Ingmar

    2014-01-01

    Summary Background: The omnipresence of nanoparticles (NPs) in numerous goods has led to a constant risk of exposure and inadvertent uptake for humans. This situation calls for thorough investigation of the consequences of NP intake. As the vast mucosa of the human gastrointestinal tract represents an attractive site of entry, we wanted to take a look on the fate that ingested NPs suffer in the gut. As a model to investigate NP uptake we used the isolated perfused rat small intestine. Differently sized fluorescent latex particles were used as exemplary anthropogenic NPs. Results: The particles were administered as bolus into the isolated intestine, and samples from the luminal, vascular and lymphatic compartments were collected over time. NP amounts in the different fluids were determined by fluorescence measurements. No particles could be detected in the vascular and lymphatic system. By contrast a major amount of NPs was found in luminal samples. Yet, a substantial share of particles could not be recovered in the fluid fractions, indicating a sink function of the intestinal tissue for NPs. A histological examination of the gut revealed that virtually no particles adhered to the epithelium or resided in the tissue, the bulk of particles seemed to be trapped in the mucus lining the gut tube. When this mucus was dissolved and removed from the gut almost the entire amount of particles missing could be recovered: over 95% of the given NPs were present in the two fractions, the luminal samples and the dissolved mucus. To foster NP uptake via an extended interaction time with the epithelium, the intestinal peristalsis was decelerated and the duration of the experiment was prolonged. Even under those conditions, no particle fluorescence was detected in the vascular and lymphatic samples. Conclusion: We could show that after intestinal exposure with a large dose of NPs the vast majority of NPs did obviously not come into contact with the epithelium but was either directly

  1. Nutrient uptake by rat enterocytes during diabetes mellitus; evidence for an increased sodium electrochemical gradient.

    PubMed Central

    Debnam, E S; Karasov, W H; Thompson, C S

    1988-01-01

    1. The effect of streptozotocin-induced diabetes (7 day duration) in rats on D-glucose uptake in vivo, the unidirectional uptake of D-glucose and L-proline in vitro, the passive uptake of L-glucose in vitro and the potential difference across the brush-border membrane has been studied. 2. Diabetes resulted in an increased carrier-mediated glucose uptake both in vivo and in vitro and a stimulation of L-proline uptake at a concentration of the amino acid (0.025 mM) at which uptake was largely Na+ dependent. Diabetes was without effect on uptake using a proline concentration of 50 mM at which transport was predominantly Na+ independent. 3. A marked hyperpolarization of the brush-border membrane and an enhanced passive glucose uptake were also evident during diabetes. 4. We conclude that the stimulation of glucose uptake in vivo in diabetic intestine involves events at the brush-border membrane. The mechanisms include an increased surface area for uptake and an enhanced transmembrane electrical gradient. The latter will have a major effect on the transport of other substrates when the uptake pathway is primarily Na+ dependent. PMID:3411516

  2. Effect of various antibiotics on modulation of intestinal microbiota and bile acid profile in mice

    SciTech Connect

    Zhang, Youcai; Limaye, Pallavi B.; Renaud, Helen J.; Klaassen, Curtis D.

    2014-06-01

    Antibiotic treatments have been used to modulate intestinal bacteria and investigate the role of intestinal bacteria on bile acid (BA) homeostasis. However, knowledge on which intestinal bacteria and bile acids are modified by antibiotics is limited. In the present study, mice were administered various antibiotics, 47 of the most abundant bacterial species in intestine, as well as individual BAs in plasma, liver, and intestine were quantified. Compared to the two antibiotic combinations (vancomycin + imipenem and cephalothin + neomycin), the three single antibiotics (metronidazole, ciprofloxacin and aztreonam) have less effect on intestinal bacterial profiles, and thus on host BA profiles and mRNA expression of genes that are important for BA homeostasis. The two antibiotic combinations decreased the ratio of Firmicutes to Bacteroidetes in intestine, as well as most secondary BAs in serum, liver and intestine. Additionally, the two antibiotic combinations significantly increased mRNA of the hepatic BA uptake transporters (Ntcp and Oatp1b2) and canalicular BA efflux transporters (Bsep and Mrp2), but decreased mRNA of the hepatic BA synthetic enzyme Cyp8b1, suggesting an elevated enterohepatic circulation of BAs. Interestingly, the two antibiotic combinations tended to have opposite effect on the mRNAs of most intestinal genes, which tended to be inhibited by vancomycin + imipenem but stimulated by cephalothin + neomycin. To conclude, the present study clearly shows that various antibiotics have distinct effects on modulating intestinal bacteria and host BA metabolism. - Highlights: • Various antibiotics have different effects on intestinal bacteria. • Antibiotics alter bile acid composition in mouse liver and intestine. • Antibiotics influence genes involved in bile acid homeostasis. • Clostridia appear to be important for secondary bile acid formation.

  3. Appreciating Oxygen

    ERIC Educational Resources Information Center

    Weiss, Hilton M.

    2008-01-01

    Photosynthetic flora and microfauna utilize light from the sun to convert carbon dioxide and water into carbohydrates and oxygen. While these carbohydrates and their derivative hydrocarbons are generally considered to be fuels, it is the thermodynamically energetic oxygen molecule that traps, stores, and provides almost all of the energy that…

  4. Oxygen safety

    MedlinePlus

    ... Watch out for splattering grease. It can catch fire. Keep children with oxygen away from the stove top and oven. Cooking ... under the bed. Keep liquids that may catch fire away from your oxygen. This includes cleaning products that contain oil, grease, ...

  5. The Cystic Fibrosis Intestine

    PubMed Central

    De Lisle, Robert C.; Borowitz, Drucy

    2013-01-01

    The clinical manifestations of cystic fibrosis (CF) result from dysfunction of the cystic fibrosis transmembrane regulator protein (CFTR). The majority of people with CF have a limited life span as a consequence of CFTR dysfunction in the respiratory tract. However, CFTR dysfunction in the gastrointestinal (GI) tract occurs earlier in ontogeny and is present in all patients, regardless of genotype. The same pathophysiologic triad of obstruction, infection, and inflammation that causes disease in the airways also causes disease in the intestines. This article describes the effects of CFTR dysfunction on the intestinal tissues and the intraluminal environment. Mouse models of CF have greatly advanced our understanding of the GI manifestations of CF, which can be directly applied to understanding CF disease in humans. PMID:23788646

  6. Oxidation and microstrucure of V-Cr-Ti alloys exposed to oxygen-containing environments

    SciTech Connect

    Natesan, K.; Uz, M.; Ulie, T.

    1997-08-01

    The objectives of this task are to (a) evaluate the oxygen uptake of several V-Cr-Ti alloys as a function of temperature and oxygen partial pressure in the exposure environment, (b) examine the microstructural characteristics of oxide scales and oxygen trapped at the grain boundaries in the substrate alloys, and (c) evaluate the influence of alloy composition on oxygen uptake and develop correlation(s) between alloy composition, exposure environment, and temperature.

  7. Elenoside increases intestinal motility

    PubMed Central

    Navarro, E; Alonso, SJ; Navarro, R; Trujillo, J; Jorge, E

    2006-01-01

    AIM: To study the effects of elenoside, an arylnaph-thalene lignan from Justicia hyssopifolia, on gastro-intestinal motility in vivo and in vitro in rats. METHODS: Routine in vivo experimental assessments were catharsis index, water percentage of boluses, intestinal transit, and codeine antagonism. The groups included were vehicle control (propylene glycol-ethanol-plant oil-tween 80), elenoside (i.p. 25 and 50 mg/kg), cisapride (i.p. 10 mg/kg), and codeine phosphate (intragastric route, 50 mg/kg). In vitro approaches used isolated rat intestinal tissues (duodenum, jejunum, and ileum). The effects of elenoside at concentrations of 3.2 x 10-4, 6.4 x 10-4 and 1.2 x 10-3 mol/L, and cisapride at 10-6 mol/L were investigated. RESULTS: Elenoside in vivo produced an increase in the catharsis index and water percentage of boluses and in the percentage of distance traveled by a suspension of activated charcoal. Codeine phosphate antagonized the effect of 25 mg/kg of elenoside. In vitro, elenoside in duodenum, jejunum and ileum produced an initial decrease in the contraction force followed by an increase. Elenoside resulted in decreased intestinal frequency in duodenum, jejunum, and ileum. The in vitro and in vivo effects of elenoside were similar to those produced by cisapride. CONCLUSION: Elenoside is a lignan with an action similar to that of purgative and prokinetics drugs. Elenoside, could be an alternative to cisapride in treatment of gastrointestinal diseases as well as a preventive therapy for the undesirable gastrointestinal effects produced by opioids used for mild to moderate pain. PMID:17131476

  8. Alcohol and the Intestine

    PubMed Central

    Patel, Sheena; Behara, Rama; Swanson, Garth R.; Forsyth, Christopher B.; Voigt, Robin M.; Keshavarzian, Ali

    2015-01-01

    Alcohol abuse is a significant contributor to the global burden of disease and can lead to tissue damage and organ dysfunction in a subset of alcoholics. However, a subset of alcoholics without any of these predisposing factors can develop alcohol-mediated organ injury. The gastrointestinal tract (GI) could be an important source of inflammation in alcohol-mediated organ damage. The purpose of review was to evaluate mechanisms of alcohol-induced endotoxemia (including dysbiosis and gut leakiness), and highlight the predisposing factors for alcohol-induced dysbiosis and gut leakiness to endotoxins. Barriers, including immunologic, physical, and biochemical can regulate the passage of toxins into the portal and systemic circulation. In addition, a host of environmental interactions including those influenced by circadian rhythms can impact alcohol-induced organ pathology. There appears to be a role for therapeutic measures to mitigate alcohol-induced organ damage by normalizing intestinal dysbiosis and/or improving intestinal barrier integrity. Ultimately, the inflammatory process that drives progression into organ damage from alcohol appears to be multifactorial. Understanding the role of the intestine in the pathogenesis of alcoholic liver disease can pose further avenues for pathogenic and treatment approaches. PMID:26501334

  9. Intestinal folate absorption

    PubMed Central

    Strum, Williamson; Nixon, Peter F.; Bertino, Joseph B.; Binder, Henry J.

    1971-01-01

    Intestinal absorption of the monoglutamate form of the principal dietary and circulating folate compound, 5-methyltetrahydrofolic acid (5-MTHF), was studied in the rat utilizing a synthetic highly purified radiolabeled diastereoisomer. Chromatography confirmed that the compound was not altered after transfer from the mucosa to the serosa. Accumulation against a concentration gradient was not observed in duodenal, jejunal, or ileal segments at 5-MTHF concentration from 0.5 to 500 nmoles/liter. Unidirectional transmural flux determination also did not indicate a significant net flux. Mucosal to serosal transfer of 5-MTHF was similar in all segments of the intestine and increased in a linear fashion with increased initial mucosal concentrations. Further, no alteration in 5-MTHF transfer was found when studied in the presence of metabolic inhibitors or folate compounds. These results indicate that 5-MTHF is not absorbed by the rat small intestine by a carrier-mediated system and suggest that 5-MTHF transfer most likely represents diffusion. Images PMID:5564397

  10. Intestinal pregnane X receptor links xenobiotic exposure and hypercholesterolemia.

    PubMed

    Sui, Yipeng; Helsley, Robert N; Park, Se-Hyung; Song, Xiulong; Liu, Zun; Zhou, Changcheng

    2015-05-01

    Recent studies have associated endocrine-disrupting chemical (EDC) exposure with the increased risk of cardiovascular disease in humans, but the underlying mechanisms responsible for these associations remain elusive. Many EDCs have been implicated in activation of the nuclear receptor pregnane X receptor (PXR), which acts as a xenobiotic sensor to regulate xenobiotic metabolism in the liver and intestine. Here we report an important role of intestinal PXR in linking xenobiotic exposure and hyperlipidemia. We identified tributyl citrate (TBC), one of a large group of Food and Drug Administration-approved plasticizers for pharmaceutical or food applications, as a potent and selective PXR agonist. TBC efficiently activated PXR and induced PXR target gene expression in vitro and in vivo. Interestingly, TBC activated intestinal PXR but did not affect hepatic PXR activity. Exposure to TBC increased plasma total cholesterol and atherogenic low-density lipoprotein cholesterol levels in wild-type mice, but not in PXR-deficient mice. TBC-mediated PXR activation stimulated the expression of an essential cholesterol transporter, Niemann-Pick C1-like 1 (NPC1L1), in the intestine. Promoter analysis revealed a DR-4 type of PXR response element in the human NPC1L1 promoter, and TBC promoted PXR recruitment onto the NPC1L1 promoter. Consistently, TBC treatment significantly increased lipid uptake by human and murine intestinal cells and deficiency of PXR inhibited TBC-elicited lipid uptake. These findings provide critical mechanistic insight for understanding the impact of EDC-mediated PXR activation on lipid homeostasis and demonstrate a potential role of PXR in mediating the adverse effects of EDCs on cardiovascular disease risk in humans. PMID:25811240

  11. Intestinal Pregnane X Receptor Links Xenobiotic Exposure and Hypercholesterolemia

    PubMed Central

    Sui, Yipeng; Helsley, Robert N.; Park, Se-Hyung; Song, Xiulong; Liu, Zun

    2015-01-01

    Recent studies have associated endocrine-disrupting chemical (EDC) exposure with the increased risk of cardiovascular disease in humans, but the underlying mechanisms responsible for these associations remain elusive. Many EDCs have been implicated in activation of the nuclear receptor pregnane X receptor (PXR), which acts as a xenobiotic sensor to regulate xenobiotic metabolism in the liver and intestine. Here we report an important role of intestinal PXR in linking xenobiotic exposure and hyperlipidemia. We identified tributyl citrate (TBC), one of a large group of Food and Drug Administration–approved plasticizers for pharmaceutical or food applications, as a potent and selective PXR agonist. TBC efficiently activated PXR and induced PXR target gene expression in vitro and in vivo. Interestingly, TBC activated intestinal PXR but did not affect hepatic PXR activity. Exposure to TBC increased plasma total cholesterol and atherogenic low-density lipoprotein cholesterol levels in wild-type mice, but not in PXR-deficient mice. TBC-mediated PXR activation stimulated the expression of an essential cholesterol transporter, Niemann-Pick C1-like 1 (NPC1L1), in the intestine. Promoter analysis revealed a DR-4 type of PXR response element in the human NPC1L1 promoter, and TBC promoted PXR recruitment onto the NPC1L1 promoter. Consistently, TBC treatment significantly increased lipid uptake by human and murine intestinal cells and deficiency of PXR inhibited TBC-elicited lipid uptake. These findings provide critical mechanistic insight for understanding the impact of EDC-mediated PXR activation on lipid homeostasis and demonstrate a potential role of PXR in mediating the adverse effects of EDCs on cardiovascular disease risk in humans. PMID:25811240

  12. Oxygen therapy and intraocular oxygenation.

    PubMed Central

    Jampol, L M

    1987-01-01

    When delivered to the corneal surface of rabbits or monkeys, 100% oxygen can significantly increase the pO2 in the aqueous humor. Under hyperbaric conditions (two atmospheres), an observed rise in the aqueous pO2 in rabbits breathing room air can be increased further by exposing the rabbit cornea to 100% oxygen. The high oxygen levels under hyperbaric conditions are mediated by intravascular and transcorneal delivery of oxygen. The increase in the pO2 levels in the aqueous can prevent sickling of intracameral human erythrocytes containing sickle hemoglobin. Thus, oxygen therapy transcorneally or systemically could potentially be used to treat a sickle cell hyphema. The exposure of rabbit eyes to 100% oxygen at the corneal surface is followed by autoregulation (constriction) of the iris vasculature. We could demonstrate no constriction in the eyes of two normal human volunteers or of four patients with chronic stable rubeosis iridis. Preretinal vitreous pO2 levels can be significantly raised by exposing monkeys to hyperbaric 100% oxygen. This procedure may be of value in treating acute, reversible ischemic inner retinal diseases. Transcorneal or vascular delivery of oxygen to the eye under normobaric or hyperbaric conditions may be effective in treating ischemic diseases of the anterior segment, such as anterior segment necrosis or rubeosis iridis, or ischemic inner retinal diseases. Images FIGURE 2 FIGURE 3 FIGURE 4 FIGURE 5 B FIGURE 5 C FIGURE 5 A FIGURE 6 PMID:3447339

  13. Intestinal absorption of triglyceride and vitamin D3 in aged and young rats

    SciTech Connect

    Holt, P.R.; Dominguez, A.A.

    1981-12-01

    (3H)Trioleyl glycerol (TO) and (14C)vitamin D3 were perfused intraduodenally for 5 hr in aged (19-21 months) and young adult (4-5 months) Sprague-Dawley rats. The rate of intestinal uptake from the gastrointestinal lumen and transport into the body of these lipids were decreased in the aged animals. Since the distribution of TO lipolytic products in the lumen was unchanged, reduced intestinal uptake rate probably occurred at the mucosal membrane. Furthermore, in the aged rats, the rate of transintestinal transport of both trioleyl glycerol and vitamin D3 was impaired. No evidence for impaired mucosal TO reesterification or for accumulation of vitamin D3 metabolites was found, suggesting that intestinal lipid accumulation resulted from a defect in lipoprotein assembly or in discharge from the mucosal cell. Impaired absorption of lipids may contribute to malnutrition and osteopenia of advancing age.

  14. Phasic study of intestinal homeostasis disruption in experimental intestinal obstruction

    PubMed Central

    Yu, Xiang-Yang; Zou, Chang-Lin; Zhou, Zhen-Li; Shan, Tao; Li, Dong-Hua; Cui, Nai-Qiang

    2014-01-01

    AIM: To investigate the phasic alteration of intestinal homeostasis in an experimental model of intestinal obstruction. METHODS: A rabbit model of intestinal obstruction was established by transforming parts of an infusion set into an in vivo pulled-type locking clamp and creating a uniform controllable loop obstruction in the mesenteric non-avascular zone 8 cm from the distal end of the ileum. The phasic alteration of intestinal homeostasis was studied after intestinal obstruction. The changes in goblet cells, intraepithelial lymphocytes, lamina propria lymphocytes, and intestinal epithelium were quantified from periodic acid-Schiff-stained sections. Ornithine decarboxylase (ODC) activity and serum citrulline levels were measured by high-performance liquid chromatography. Claudin 1 mRNA expression was examined by real-time polymerase chain reaction analysis. Intestinal microorganisms, wet/dry weight ratios, pH values, and endotoxin levels were determined at multiple points after intestinal obstruction. Furthermore, the number and ratio of CD3+, CD4+ and CD8+ T cells were determined by flow cytometry, and secretory IgA levels were measured with an enzyme-linked immunosorbent assay. RESULTS: A suitable controllable rabbit model of intestinal obstruction was established. Intestinal obstruction induced goblet cell damage and reduced cell number. Further indicators of epithelial cell damage were observed as reduced serum citrulline levels and claudin 1 gene expression, and a transient increase in ODC activity. In addition, the wet/dry weight ratio and pH of the intestinal lumen were also dramatically altered. The ratio of Bacillus bifidus and enterobacteria was reversed following intestinal obstruction. The number and area of Peyer’s patches first increased then sharply decreased after the intestinal obstruction, along with an alteration in the ratio of CD4/CD8+ T cells, driven by an increase in CD3+ and CD8+ T cells and a decrease in CD4+ T cells. The number of

  15. How to make an intestine

    PubMed Central

    Wells, James M.; Spence, Jason R.

    2014-01-01

    With the high prevalence of gastrointestinal disorders, there is great interest in establishing in vitro models of human intestinal disease and in developing drug-screening platforms that more accurately represent the complex physiology of the intestine. We will review how recent advances in developmental and stem cell biology have made it possible to generate complex, three-dimensional, human intestinal tissues in vitro through directed differentiation of human pluripotent stem cells. These are currently being used to study human development, genetic forms of disease, intestinal pathogens, metabolic disease and cancer. PMID:24496613

  16. Modulation of intestinal L-glutamate transport by luminal leptin.

    PubMed

    Fanjul, Carmen; Barrenetxe, Jaione; Lostao, María Pilar; Ducroc, Robert

    2015-06-01

    Leptin is secreted into the digestive tract and contributes to the absorption of dietary molecules by regulating transporters activity. Here, we studied the effect of luminal leptin on the intestinal transport of L-glutamate, an important component of human diet. We examined the effect of leptin on L-glutamate uptake in rat intestine in vitro measuring glutamate-induced short-circuit current (Isc) in Ussing chambers and L-[(3)H (U)]-glutamate uptake in jejunal everted rings. Glutamate-induced Isc was only observed in Na(+)-free conditions. This Isc was concentration (1-60 mmol L(-1)) and pH dependent. Luminal leptin increased glutamate Isc (∼100 %). Dose-response curve showed a biphasic pattern, with maximal stimulations observed at 10(-13) and 10(-10) mmol L(-1), that were sensitive to leptin receptor antagonist. In everted rings, two glutamate transport mechanisms were distinguished: a Na(+)-dependent, H(+)-independent, that was inhibited by leptin (∼20 %), and a Na(+)-independent but H(+)-dependent, that was enhanced by leptin (∼20 %), in line with data obtained in Ussing chambers. Altogether, these data reveal original non-monotonic effect of luminal leptin in the intestine and demonstrate a new role for this hormone in the modulation of L-glutamate transport, showing that luminal active gut peptides can influence absorption of amino acids. PMID:25935421

  17. Effects of an enteric anaerobic bacterial culture supernatant and deoxycholate on intestinal calcium absorption and disaccharidase activity.

    PubMed Central

    Walshe, K; Healy, M J; Speekenbrink, A B; Keane, C T; Weir, D G; O'Moore, R R

    1990-01-01

    Fifty two strains of anaerobic bacteria isolated from the upper gut of patients with small intestinal bacterial overgrowth were screened for phospholipase activity. Bacteroides melaninogenicus spp intermedius had the greatest activity. The effects of culture supernatants of this organism and deoxycholate on intestinal calcium absorption and disaccharidase activity were studied using a rat closed loop model. The supernatant decreased the in vitro uptake of calcium by 15% (p less than 0.001). Deoxycholate reduced calcium uptake by 16% (p less than 0.001). Combined culture supernatant and deoxycholate reduced calcium uptake by 39% (p less than 0.001) suggesting a potentiation of supernatant activity by deoxycholate. Culture supernatant and deoxycholate, both alone and combined, significantly reduced lactase, sucrase, and maltase activity. Electron microscopic evidence showed degeneration of microvilli, disruption of mitochondrial structure, and swelling of the endoplasmic reticulum after exposure of the intestinal loops to the supernatant or deoxycholate. Images Figure 2 Figure 3 Figure 4 PMID:1973395

  18. Characterization of the rabbit intestinal fructose transporter (GLUT5).

    PubMed Central

    Miyamoto, K; Tatsumi, S; Morimoto, A; Minami, H; Yamamoto, H; Sone, K; Taketani, Y; Nakabou, Y; Oka, T; Takeda, E

    1994-01-01

    Recent studies suggest that the jejunal/kidney-type facilitative glucose transporter (GLUT5) functions as a high-affinity D-fructose transporter. However, its precise role in the small intestine is not clear. In an attempt to identify the fructose transporter in the small intestine, we measured fructose uptake in Xenopus oocytes expressing jejunal mRNA from five species (rat, mouse, rabbit, hamster and guinea-pig). Only jejunal mRNA from the rabbit significantly increased fructose uptake. We also cloned a rabbit GLUT5 cDNA from a jejunal library The predicted amino acid sequence of the 487-residue rabbit GLUT5 showed 72.3 and 67.1% identity with human and rat GLUT5 respectively. Northern-blot analysis revealed GLUT5 transcripts in rabbit duodenum, jejunum and, to a lesser extent, kidney. After separation of rabbit jejunal mRNA on a sucrose density gradient, the fractions that conferred D-fructose transport activity in oocytes also hybridized with rabbit GLUT5 cDNA. Hybrid depletion of jejunal mRNA with a GLUT5 antisense oligonucleotide markedly inhibited the mRNA-induced fructose uptake in oocytes. Immunoblot analysis indicated that GLUT5 (49 kDa) is located in the brush-border membrane of rabbit intestinal epithelial cells. Xenopus oocytes injected with rabbit GLUT5 cRNA exhibited fructose uptake activity with a Km of 11 mM for D-fructose. D-Fructose transport by GLUT5 was significantly inhibited by D-glucose and D-galactose. D-Fructose uptake in brush-border membrane vesicles shows a Km similar to that of GLUT5, but was not inhibited by D-glucose or D-galactose. Finally, cytochalasin B photolabelled a 49 kDa protein in rabbit brush-border-membrane preparations that was immunoprecipitated by antibodies to GLUT5. Our results suggest that GLUT5 functions as a fructose transporter in rabbit small intestine. However, biochemical properties of fructose transport in Xenopus oocytes injected with GLUT5 cRNA differed from those in rabbit jejunal vesicles. Images Figure 2

  19. Human, rat and chicken small intestinal Na+-Cl−-creatine transporter: functional, molecular characterization and localization

    PubMed Central

    Peral, M J; García-Delgado, M; Calonge, M L; Durán, J M; De La Horra, M C; Wallimann, T; Speer, O; Ilundáin, A A

    2002-01-01

    In spite of all the fascinating properties of oral creatine supplementation, the mechanism(s) mediating its intestinal absorption has(have) not been investigated. The purpose of this study was to characterize intestinal creatine transport. [14C]Creatine uptake was measured in chicken enterocytes and rat ileum, and expression of the creatine transporter CRT was examined in human, rat and chicken small intestine by reverse transcription-polymerase chain reaction, Northern blot, in situ hybridization, immunoblotting and immunohistochemistry. Results show that enterocytes accumulate creatine against its concentration gradient. This accumulation was electrogenic, Na+- and Cl−-dependent, with a probable stoichiometry of 2 Na+: 1 Cl−: 1 creatine, and inhibited by ouabain and iodoacetic acid. The kinetic study revealed a Km for creatine of 29 μm. [14C]Creatine uptake was efficiently antagonized by non-labelled creatine, guanidinopropionic acid and cyclocreatine. More distant structural analogues of creatine, such as GABA, choline, glycine, β-alanine, taurine and betaine, had no effect on intestinal creatine uptake, indicating a high substrate specificity of the creatine transporter. Consistent with these functional data, messenger RNA for CRT was detected only in the cells lining the intestinal villus. The sequences of partial clones, and of the full-length cDNA clone, isolated from human and rat small intestine were identical to previously cloned CRT cDNAs. Immunological analysis revealed that CRT protein was mainly associated with the apical membrane of the enterocytes. This study reports for the first time that mammalian and avian enterocytes express CRT along the villus, where it mediates high-affinity, Na+- and Cl−-dependent, apical creatine uptake. PMID:12433955

  20. Intestinal transplantation: living related.

    PubMed

    Pollard, S G

    1997-01-01

    The use of live donors in intestinal transplantation could potentially both reduce the severity of rejection responses against this highly immunogenic organ by better tissue matching and also reduce cold ischaemia times. These two advantages over cadaveric grafts could preserve mucosal integrity and reduce the risk of systemic sepsis from bacterial translocation. The disadvantages of live donation are the inherent risk to the donor and the compromise of using a shorter graft. Although only a handful of such cases have been performed, the success rate has been high and this is a therapeutic modality which should be explored further. PMID:9536535

  1. Pro-oxidant environment of the colon compared to the small intestine may contribute to greater cancer susceptibility.

    PubMed

    Sanders, Lisa M; Henderson, Cara E; Hong, Mee Young; Barhoumi, Rola; Burghardt, Robert C; Carroll, Raymond J; Turner, Nancy D; Chapkin, Robert S; Lupton, Joanne R

    2004-05-28

    The colon and small intestine have inherent differences (e.g. redox status) that may explain the variation in cancer occurrence at these two sites. This study examined basal and induced (oxidative challenge) reactive oxygen species (ROS) generation, antioxidant enzyme activity and oxidative DNA damage. Basal ROS and antioxidant enzyme activities in the colon were greater than in the small intestine. During oxidative stress, 8-oxo-deoxyguanosine (8-oxodG) DNA adducts in the colon exceeded levels in the small intestine concomitant with increased ROS. Thus the colon responds to oxidative stress less effectively than the small intestine, possibly contributing to increased cancer incidence at this site. PMID:15142673

  2. Reversible oxygen scavenging at room temperature using electrochemically reduced titanium oxide nanotubes

    NASA Astrophysics Data System (ADS)

    Close, Thomas; Tulsyan, Gaurav; Diaz, Carlos A.; Weinstein, Steven J.; Richter, Christiaan

    2015-05-01

    A material capable of rapid, reversible molecular oxygen uptake at room temperature is desirable for gas separation and sensing, for technologies that require oxygen storage and oxygen splitting such as fuel cells (solid-oxide fuel cells in particular) and for catalytic applications that require reduced oxygen species (such as removal of organic pollutants in water and oil-spill remediation). To date, however, the lowest reported temperature for a reversible oxygen uptake material is in the range of 200-300 °C, achieved in the transition metal oxides SrCoOx (ref. 1) and LuFe2O4+x (ref. 2) via thermal cycling. Here, we report rapid and reversible oxygen scavenging by TiO2-x nanotubes at room temperature. The uptake and release of oxygen is accomplished by an electrochemical rather than a standard thermal approach. We measure an oxygen uptake rate as high as 14 mmol O2 g-1 min-1, ˜2,400 times greater than commercial, irreversible oxygen scavengers. Such a fast oxygen uptake at a remarkably low temperature suggests a non-typical mechanistic pathway for the re-oxidation of TiO2-x. Modelling the diffusion of oxygen, we show that a likely pathway involves ‘exceptionally mobile’ interstitial oxygen produced by the oxygen adsorption and decomposition dynamics, recently observed on the surface of anatase.

  3. Defective intestinal amino acid absorption in Ace2 null mice.

    PubMed

    Singer, Dustin; Camargo, Simone M R; Ramadan, Tamara; Schäfer, Matthias; Mariotta, Luca; Herzog, Brigitte; Huggel, Katja; Wolfer, David; Werner, Sabine; Penninger, Josef M; Verrey, François

    2012-09-15

    Mutations in the main intestinal and kidney luminal neutral amino acid transporter B(0)AT1 (Slc6a19) lead to Hartnup disorder, a condition that is characterized by neutral aminoaciduria and in some cases pellagra-like symptoms. These latter symptoms caused by low-niacin are thought to result from defective intestinal absorption of its precursor L-tryptophan. Since Ace2 is necessary for intestinal B(0)AT1 expression, we tested the impact of intestinal B(0)AT1 absence in ace2 null mice. Their weight gain following weaning was decreased, and Na(+)-dependent uptake of B(0)AT1 substrates measured in everted intestinal rings was defective. Additionally, high-affinity Na(+)-dependent transport of L-proline, presumably via SIT1 (Slc6a20), was absent, whereas glucose uptake via SGLT1 (Slc5a1) was not affected. Measurements of small intestine luminal amino acid content following gavage showed that more L-tryptophan than other B(0)AT1 substrates reach the ileum in wild-type mice, which is in line with its known lower apparent affinity. In ace2 null mice, the absorption defect was confirmed by a severalfold increase of L-tryptophan and of other neutral amino acids reaching the ileum lumen. Furthermore, plasma and muscle levels of glycine and L-tryptophan were significantly decreased in ace2 null mice, with other neutral amino acids displaying a similar trend. A low-protein/low-niacin diet challenge led to differential changes in plasma amino acid levels in both wild-type and ace2 null mice, but only in ace2 null mice to a stop in weight gain. Despite the combination of low-niacin with a low-protein diet, plasma niacin concentrations remained normal in ace2 null mice and no pellagra symptoms, such as photosensitive skin rash or ataxia, were observed. In summary, mice lacking Ace2-dependent intestinal amino acid transport display no total niacin deficiency nor clear pellagra symptoms, even under a low-protein and low-niacin diet, despite gross amino acid homeostasis alterations

  4. Mieap suppresses murine intestinal tumor via its mitochondrial quality control

    PubMed Central

    Tsuneki, Masayuki; Nakamura, Yasuyuki; Kinjo, Takao; Nakanishi, Ruri; Arakawa, Hirofumi

    2015-01-01

    Mieap, a novel p53-inducible protein, plays a key role in maintaining healthy mitochondria in various pathophysiological states. Here, we show that Mieap deficiency in ApcMin/+ mice is strikingly associated with the malignant progression of murine intestinal tumors. To understand the role that Mieap plays in in vivo tumorigenesis, we generated Mieap heterozygous (ApcMin/+ Mieap+/−) and homozygous (ApcMin/+ Mieap−/−) ApcMin/+ mice. Interestingly, the ApcMin/+ mice with the Mieap+/− and Mieap−/− genetic background revealed remarkable shortening of the lifetime compared to ApcMin/+ mice because of severe anemia. A substantial increase in the number and size of intestinal polyps was associated with Mieap gene deficiency. Histopathologically, intestinal tumors in the Mieap-deficient ApcMin/+ mice clearly demonstrated advanced grades of adenomas and adenocarcinomas. We demonstrated that the significant increase in morphologically unhealthy mitochondria and trace accumulations of reactive oxygen species may be mechanisms underlying the increased malignant progression of the intestinal tumors of Mieap-deficient ApcMin/+ mice. These findings suggest that the Mieap-regulated mitochondrial quality control plays a critical role in preventing mouse intestinal tumorigenesis. PMID:26216032

  5. Glutathione plays a role in the chick intestinal calcium absorption.

    PubMed

    Tolosa de Talamoni, N; Marchionatti, A; Baudino, V; Alisio, A

    1996-10-01

    DL-buthionine-S,R-sulfoximine (BSO) administration to vitamin D-deficient chicks treated with cholecalciferol produces a rapid decrease in the Ca2+ transfer from lumen-to-plasma and in the intestinal glutathione content. This response was reversed by addition of glutathione monoester to the intestinal sac. Variables related to the Ca2+ homeostasis such as plasma Ca and P, and intestinal calbindin D28k were not modified by BSO given to vitamin D-deficient chicks treated with cholecalciferol. Intestinal alkaline phosphatase activity, on the contrary, was highly reduced by BSO in vitamin D-deficient chicks treated with vitamin D3. This effect showed time and dose-dependency. Although the mechanism/s of action of BSO on the intestinal Ca absorption is unknown, it is quite possible that thiol groups of protein involved in the Ca2+ transport are affected by the GSH depletion and/or by block of the antioxidant ability of vitamin D3. Thus, reactive oxygen compounds would be increased and, therefore, the Ca2+ movement from lumen to plasma decreases. PMID:8916550

  6. Anaerobic respiration of Escherichia coli in the mouse intestine.

    PubMed

    Jones, Shari A; Gibson, Terri; Maltby, Rosalie C; Chowdhury, Fatema Z; Stewart, Valley; Cohen, Paul S; Conway, Tyrrell

    2011-10-01

    The intestine is inhabited by a large microbial community consisting primarily of anaerobes and, to a lesser extent, facultative anaerobes, such as Escherichia coli, which we have shown requires aerobic respiration to compete successfully in the mouse intestine (S. A. Jones et al., Infect. Immun. 75:4891-4899, 2007). If facultative anaerobes efficiently lower oxygen availability in the intestine, then their sustained growth must also depend on anaerobic metabolism. In support of this idea, mutants lacking nitrate reductase or fumarate reductase have extreme colonization defects. Here, we further explore the role of anaerobic respiration in colonization using the streptomycin-treated mouse model. We found that respiratory electron flow is primarily via the naphthoquinones, which pass electrons to cytochrome bd oxidase and the anaerobic terminal reductases. We found that E. coli uses nitrate and fumarate in the intestine, but not nitrite, dimethyl sulfoxide, or trimethylamine N-oxide. Competitive colonizations revealed that cytochrome bd oxidase is more advantageous than nitrate reductase or fumarate reductase. Strains lacking nitrate reductase outcompeted fumarate reductase mutants once the nitrate concentration in cecal mucus reached submillimolar levels, indicating that fumarate is the more important anaerobic electron acceptor in the intestine because nitrate is limiting. Since nitrate is highest in the absence of E. coli, we conclude that E. coli is the only bacterium in the streptomycin-treated mouse large intestine that respires nitrate. Lastly, we demonstrated that a mutant lacking the NarXL regulator (activator of the NarG system), but not a mutant lacking the NarP-NarQ regulator, has a colonization defect, consistent with the advantage provided by NarG. The emerging picture is one in which gene regulation is tuned to balance expression of the terminal reductases that E. coli uses to maximize its competitiveness and achieve the highest possible population in

  7. Halide uptake by the filamentous ascomycete Neocosmospora vasinfecta.

    PubMed Central

    Miller, A G; Budd, K

    1975-01-01

    The uptake of Cl minus by the ascomycetes Neocosmospora vasinfecta was investigated. Intramycelial concentrations of more than 55 mM (890-fold the external concentration) were reached. Accumulation was as inorganic Cl minus and nystatin induced total loss of mycelial Cl minus without extensive protein loss, implying that Cl minus retention was not due to binding to macromolecules. Cl minus transport was largely unidirectional with efflux being low under all conditions. Uptake was temperature dependent (maximal Arrhenius activation energy of 18.0 kcal/mol) and was severely reduced by KCN, dicyclohexylcarbodiimide, and anaerobiosis. A comparison with the inhibition of oxygen uptake under the same conditions implied that Cl minus transport was not directly coupled to aerobic electron transport. Cl minus uptake was a saturatable function of the external Cl minus concentration, and apparent Km values of 6.4 times 10-6 M and 10-4 M were calculated. Of the anions tested, only Br minus effectively inhibited Cl minus uptake and I minus, NO3 minus, SO4 minus 2, HCO3 minus, and H2PO4 minus were without effect. Cl minus uptake did not require concomitant cation uptake. PMID:234943

  8. Maximal oxygen uptake validation in children with expiratory flow limitation.

    PubMed

    Robben, Katherine E; Poole, David C; Harms, Craig A

    2013-02-01

    A two-test protocol (incremental/ramp (IWT) + supramaximal constant-load (CWR)) to affirm max and obviate reliance on secondary criteria has only been validated in highly fit children. In girls (n = 15) and boys (n = 12) with a wide range of VO2max (17-47 ml/kg/min), we hypothesized that this procedure would evince a VO2-WR plateau and unambiguous VO2max even in the presence of expiratory flow limitation (EFL). A plateau in the VO2-work rate relationship occurred in 75% of subjects irrespective of EFL There was a range in RER at max exercise for girls (0.97-1.14; mean 1.06 ± 0.04) and boys (0.98-1.09; mean 1.03 ± 0.03) such that 3/15 girls and 2/12 boys did not achieve the criterion RER. Moreover, in girls with RER > 1.0 it would have been possible to achieve this criterion at 78% VO2max. Boys achieved 92% VO2max at RER = 1.0. This was true also for HRmax where 8/15 girls' and 6/12 boys' VO2max would have been rejected based on HRmax being < 90% of age-predicted HRmax. In those who achieved the HRmax criterion, it represented a VO2 of 86% (girls) and 87% (boys) VO2max. We conclude that this two-test protocol confirms VO2max in children across a threefold range of VO2max irrespective of EFL and circumvents reliance on secondary criteria. PMID:23406709

  9. Alterations in the Intestinal Assimilation of Oxidized PUFAs Are Ameliorated by a Polyphenol-Rich Grape Seed Extract in an In Vitro Model and Caco-2 Cells123

    PubMed Central

    Maestre, Rodrigo; Douglass, John D.; Kodukula, Sarala; Medina, Isabel; Storch, Judith

    2013-01-01

    The (n-3) PUFAs 20:5 (n-3) (EPA) and 22:6 (n-3) (DHA) are thought to benefit human health. The presence of prooxidant compounds in foods, however, renders them susceptible to oxidation during both storage and digestion. The development of oxidation products during digestion and the potential effects on intestinal PUFA uptake are incompletely understood. In the present studies, we examined: 1) the development and bioaccessibility of lipid oxidation products in the gastrointestinal lumen during active digestion of fatty fish using the in vitro digestive tract TNO Intestinal Model-1 (TIM-1); 2) the mucosal cell uptake and metabolism of oxidized compared with unoxidized PUFAs using Caco-2 intestinal cells; and 3) the potential to limit the development of oxidation products in the intestine by incorporating antioxidant polyphenols in food. We found that during digestion, the development of oxidation products occurs in the stomach compartment, and increased amounts of oxidation products became bioaccessible in the jejunal and ileal compartments. Inclusion of a polyphenol-rich grape seed extract (GSE) during the digestion decreased the amounts of oxidation products in the stomach compartment and intestinal dialysates (P < 0.05). In Caco-2 intestinal cells, the uptake of oxidized (n-3) PUFAs was ~10% of the uptake of unoxidized PUFAs (P < 0.05) and addition of GSE or epigallocatechin gallate protected against the development of oxidation products, resulting in increased uptake of PUFAs (P < 0.05). These results suggest that addition of polyphenols during active digestion can limit the development of (n-3) PUFA oxidation products in the small intestine lumen and thereby promote intestinal uptake of the beneficial, unoxidized, (n-3) PUFAs. PMID:23325921

  10. Oxygen Incorporation in Rubrene Single Crystals

    PubMed Central

    Mastrogiovanni, Daniel D. T.; Mayer, Jeff; Wan, Alan S.; Vishnyakov, Aleksey; Neimark, Alexander V.; Podzorov, Vitaly; Feldman, Leonard C.; Garfunkel, Eric

    2014-01-01

    Single crystal rubrene is a model organic electronic material showing high carrier mobility and long exciton lifetime. These properties are detrimentally affected when rubrene is exposed to intense light under ambient conditions for prolonged periods of time, possibly due to oxygen up-take. Using photoelectron, scanning probe and ion-based methods, combined with an isotopic oxygen exposure, we present direct evidence of the light-induced reaction of molecular oxygen with single crystal rubrene. Without a significant exposure to light, there is no reaction of oxygen with rubrene for periods of greater than a year; the crystal's surface (and bulk) morphology and chemical composition remain essentially oxygen-free. Grand canonical Monte Carlo computations show no sorbtion of gases into the bulk of rubrene crystal. A mechanism for photo-induced oxygen inclusion is proposed. PMID:24786311

  11. [INTESTINAL TRANSPLANTATION IN PEDIATRICS

    PubMed

    Alarcón M, Pedro; Alarcón M, Jorge

    1997-01-01

    Intestinal Transplantation used to be an utopia in Medicine, and this was mainly due to the factor that the surgical technique was not the best at the beginning. When this was perfectioned, the next obstacle for the adequate progress of this surgery was the limited availability of anti-rejection drugs due to the fact that Ciclosporine has been and still is a drug of relative effectiveness. With the discovery of new anti-rejection drugs and with a best knowledge of the concomitant liver transplantation roll on the prognosis of these patients, it was possible to get in this decade, specifically in the last 2 years, extraordinary results; for example, from 170 pacients who underwent intestinal transplantation around the world, more than half were done by the University of Pittsburg. This university reported a survival of 62%. But, this percentage has been improved even more, the University of Miami reported a survival of 70% through the use of corticoides and two powerful anti-rejection drugs: FK-506 and Mycophelate. PMID:12219105

  12. Regulation of Intestinal Glucose Absorption by Ion Channels and Transporters

    PubMed Central

    Chen, Lihong; Tuo, Biguang; Dong, Hui

    2016-01-01

    The absorption of glucose is electrogenic in the small intestinal epithelium. The major route for the transport of dietary glucose from intestinal lumen into enterocytes is the Na+/glucose cotransporter (SGLT1), although glucose transporter type 2 (GLUT2) may also play a role. The membrane potential of small intestinal epithelial cells (IEC) is important to regulate the activity of SGLT1. The maintenance of membrane potential mainly depends on the activities of cation channels and transporters. While the importance of SGLT1 in glucose absorption has been systemically studied in detail, little is currently known about the regulation of SGLT1 activity by cation channels and transporters. A growing line of evidence suggests that cytosolic calcium ([Ca2+]cyt) can regulate the absorption of glucose by adjusting GLUT2 and SGLT1. Moreover, the absorption of glucose and homeostasis of Ca2+ in IEC are regulated by cation channels and transporters, such as Ca2+ channels, K+ channels, Na+/Ca2+ exchangers, and Na+/H+ exchangers. In this review, we consider the involvement of these cation channels and transporters in the regulation of glucose uptake in the small intestine. Modulation of them may be a potential strategy for the management of obesity and diabetes. PMID:26784222

  13. OXYGEN TRANSPORT CERAMIC MEMBRANES

    SciTech Connect

    Dr. Sukumar Bandopadhyay; Dr. Nagendra Nagabhushana

    2002-04-01

    This report covers the following tasks: Task 1--Design, fabricate and evaluate ceramic to metal seals based on graded ceramic powder/metal braze joints; Task 2--Evaluate the effect of defect configuration on ceramic membrane conductivity and long term chemical and structural stability; Task 3--Determine materials mechanical properties under conditions of high temperatures and reactive atmospheres; Task 4--Evaluate phase stability and thermal expansion of candidate perovskite membranes and develop techniques to support these materials on porous metal structures; Task 5--Assess the microstructure of membrane materials to evaluate the effects of vacancy-impurity association, defect clusters, and vacancy-dopant association on the membrane performance and stability; and Task 6--Measure kinetics of oxygen uptake and transport in ceramic membrane materials under commercially relevant conditions using isotope labeling techniques.

  14. 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.

  15. MicroRNA-682-mediated downregulation of PTEN in intestinal epithelial cells ameliorates intestinal ischemia–reperfusion injury

    PubMed Central

    Liu, Z; Jiang, J; Yang, Q; Xiong, Y; Zou, D; Yang, C; Xu, J; Zhan, H

    2016-01-01

    Intestinal ischemia–reperfusion (I/R) injury causes inflammation and tissue damage and contributes to high morbidity and mortality, but the underlying mechanism remains elusive and effective therapies are still lacking. We report here a critical role of the microRNA 682 (miR-682) as a key regulator and therapeutic target in intestinal I/R injury. MiR-682 was markedly induced in intestinal epithelial cells (IECs) during intestinal ischemia in mice and in the human colonic epithelial cells during hypoxia, but was undetected rapidly after intestinal reperfusion in IEC of mice. MiR-682 induction during hypoxia was modulated by hypoxia-inducible factor-1α (HIF-1α). On lentivirus-mediated miR-682 overexpression in vivo during intestinal reperfusion or miR-682 mimic transfection in vitro during hypoxia, miR-682 decreased the expression of phosphatase and tensin homolog (PTEN) and subsequently activated nuclear translocation of nuclear factor kappa B (NF-κB) p65. Consequently, NF-κB activation by miR-682-mediated PTEN downregulation prevented reactive oxygen species (ROS) induction, inflammatory reaction, mitochondrial-mediated apoptosis and IEC apoptosis. The effect of miR-682-mediated PTEN/NF-κB pathway on IECs resulted in protection against intestinal I/R injury in mice. However, NF-κB chemical inhibitor reversed miR-682-mediated decreased PTEN expression, ROS induction, inflammation and IEC apoptosis. Collectively, these results identify a novel miR-682/PTEN/NF-κBp65 signaling pathway in IEC injury induced by I/R that could be targeted for therapy. PMID:27124584

  16. Involvement of concentrative nucleoside transporter 1 in intestinal absorption of trifluorothymidine, a novel antitumor nucleoside, in rats.

    PubMed

    Okayama, Takashige; Yoshisue, Kunihiro; Kuwata, Keizo; Komuro, Masahito; Ohta, Shigeru; Nagayama, Sekio

    2012-02-01

    ααα-Trifluorothymidine (TFT), an anticancer nucleoside analog, is a potent thymidylate synthase inhibitor. TFT exerts its antitumor activity primarily by inducing DNA fragmentation after incorporation of the triphosphate form of TFT into the DNA. Although an oral combination of TFT and a thymidine phosphorylase inhibitor has been clinically developed, there is little information regarding TFT absorption. Therefore, we investigated TFT absorption in the rat small intestine. After oral administration of TFT in rats, more than 75% of the TFT was absorbed. To identify the uptake transport system, uptake studies were conducted by using everted sacs prepared from rat small intestines. TFT uptake was saturable, significantly reduced under Na(+)-free conditions, and strongly inhibited by the addition of an endogenous pyrimidine nucleoside. From these results, we suggested the involvement of concentrative nucleoside transporters (CNTs) in TFT absorption into rat small intestine. In rat small intestines, the mRNAs coding for rat CNT1 (rCNT1) and rCNT2, but not for rCNT3, were predominantly expressed. To investigate the roles of rCNT1 and rCNT2 in TFT uptake, we conducted uptake assays by using Xenopus laevis oocytes injected with rCNT1 complementary RNA (cRNA) and rCNT2 cRNA. TFT uptake by X. laevis oocytes injected with rCNT1 cRNA, and not rCNT2 cRNA, was significantly greater than that by water-injected oocytes. In addition, in situ single-pass perfusion experiments performed using rat jejunum regions showed that thymidine, a substrate for CNT1, strongly inhibited TFT uptake. In conclusion, TFT is absorbed via rCNT1 in the intestinal lumen in rats. PMID:22076553

  17. Putrescine uptake in saintpaulia petals.

    PubMed

    Bagni, N; Pistocchi, R

    1985-02-01

    Putrescine uptake and the kinetics of this uptake were studied in petals of Saintpaulia ionantha Wendl. Uptake experiments of [(3)H] or [(14)C] putrescine were done on single petals at room temperature at various pH values. The results show that putrescine uptake occurs against a concentration gradient at low external putrescine concentration (0.5-100 micromolar) and follows a concentration gradient at higher external putrescine concentrations (100 micromolar to 100 millimolar). 2,4-Dinitrophenol and carbonylcyanide-m-chlorophenylhydrazone, two uncouplers, had no effect on putrescine uptake. Uptake rates were constant for 2 hours, reaching a maximum after 3 to 4 hours. Putrescine uptake depended markedly on the external pH and two maxima were observed: at low external concentrations of putrescine, the optimum was at pH 5 to 5.5; at higher concentrations the optimum was at pH 8. PMID:16664065

  18. Real-time quantification of fatty acid uptake using a novel fluorescence assay.

    PubMed

    Liao, Jinfang; Sportsman, Richard; Harris, Jeff; Stahl, Andreas

    2005-03-01

    Uptake of nonesterified long-chain fatty acids (LCFAs) into many cell types and organs such as liver, heart, intestine, and skeletal muscle occurs primarily through a saturable, protein-mediated mechanism. Membrane proteins that increase the uptake of LCFAs, such as FAT/CD36 and fatty acid transport proteins, represent significant therapeutic targets for the treatment of metabolic disorders, including type 2 diabetes. However, currently available methods for the quantification of LCFA uptake neither allow for real-time measurements of uptake kinetics nor are ideally suited for the development of LCFA uptake inhibitors in high-throughput screens. To address both problems, we developed a LCFA uptake assay using a fluorescently labeled fatty acid and a nontoxic cell-impermeable quenching agent that allows fatty acid transport to be measured in real time using fluorescence plate readers or standard fluorescence microscopy. With this assay, we faithfully reproduced known differentiation- and hormone-induced changes in LCFA uptake by 3T3-L1 cells and determined LCFA uptake kinetics with previously unobtainable temporal resolution. Applications of this novel assay should facilitate new insights into the biology of fatty acid uptake and provide new means for obesity-related drug discovery. PMID:15547301

  19. Regional distribution of solute carrier mRNA expression along the human intestinal tract.

    PubMed

    Meier, Yvonne; Eloranta, Jyrki J; Darimont, Jutta; Ismair, Manfred G; Hiller, Christian; Fried, Michael; Kullak-Ublick, Gerd A; Vavricka, Stephan R

    2007-04-01

    Intestinal absorption of drugs, nutrients, and other compounds is mediated by uptake transporters expressed at the apical enterocyte membrane. These compounds are returned to the intestinal lumen or released into portal circulation by intestinal efflux transporters expressed at apical or basolateral membranes, respectively. One important transporter superfamily, multiple members of which are intestinally expressed, are the solute carriers (SLCs). SLC expression levels may determine the pharmacokinetics of drugs that are substrates of these transporters. In this study we characterize the distribution of 15 human SLC transporter mRNAs in histologically normal biopsies from five regions of the intestine of 10 patients. The mRNA expression levels of CNT1, CNT2, apical sodium-dependent bile acid transporter (ABST), serotonin transporter (SERT), PEPT1, and OCTN2 exhibit marked differences between different regions of the intestine: the first five are predominantly expressed in the small intestine, whereas OCTN2 exhibits strongest expression in the colon. Two transporter mRNAs studied (OCTN1, OATP2B1) are expressed at similar levels in all gut sections. In addition, ENT2 mRNA is present at low levels across the colon, but not in the small intestine. The other six SLC mRNAs studied are not expressed in the intestine. Quantitative knowledge of transporter expression levels in different regions of the human gastrointestinal tract could be useful for designing intestinal delivery strategies for orally administered drugs. Furthermore, changes in transporter expression that occur in pathological states, such as inflammatory bowel disease, can now be defined more precisely by comparison with the expression levels measured in healthy individuals. PMID:17220238

  20. Role of organic anion-transporting polypeptides for cellular mesalazine (5-aminosalicylic acid) uptake.

    PubMed

    König, Jörg; Glaeser, Hartmut; Keiser, Markus; Mandery, Kathrin; Klotz, Ulrich; Fromm, Martin F

    2011-06-01

    The therapeutic effects and metabolism of mesalazine (5-aminosalicylic acid) in patients with inflammatory bowel disease require intracellular accumulation of the drug in intestinal epithelial cells and hepatocytes. The molecular mechanisms of mesalazine uptake into cells have not been characterized so far. Using human embryonic kidney cells stably expressing uptake transporters of the organic anion-transporting polypeptide (OATP) family, which are expressed in human intestine and/or liver, we found that mesalazine uptake is mediated by OATP1B1, OATP1B3, and OATP2B1 but not by OATP1A2 and OATP4A1. Moreover, genetic variations (*1b, *5, *15) in the SLCO1B1 gene encoding OATP1B1 reduced the K(m) value for mesalazine uptake from 55.1 to 16.3, 24.3, and 32.4 μM, respectively, and the respective V(max) values. Finally, budesonide, cyclosporine, and rifampin were identified as inhibitors of OATP1B1-, OATP1B3-, and OATP2B1-meditated mesalazine uptake. These in vitro data indicate that OATP-mediated uptake and its modification by genetic factors and comedications may play a role for mesalazine effects. PMID:21430235

  1. Oxygen-Concentrating Cell

    NASA Technical Reports Server (NTRS)

    Buehler, K.

    1986-01-01

    High-purity oxygen produced from breathing air or from propellantgrade oxygen in oxygen-concentrating cell. Operating economics of concentrator attractive: Energy consumption about 4 Wh per liter of oxygen, slightly lower than conventional electrochemical oxygen extractors.

  2. Using oxygen at home

    MedlinePlus

    ... DO NOT use oil-based products, such as petroleum jelly (Vaseline). Ask your oxygen equipment provider about ... oxygen; Hypoxia - home oxygen; Hospice - home oxygen References American Thoracic Society. Why do I need oxygen therapy? ...

  3. [Malaria and intestinal protozoa].

    PubMed

    Rojo-Marcos, Gerardo; Cuadros-González, Juan

    2016-03-01

    Malaria is life threatening and requires urgent diagnosis and treatment. Incidence and mortality are being reduced in endemic areas. Clinical features are unspecific so in imported cases it is vital the history of staying in a malarious area. The first line treatments for Plasmodium falciparum are artemisinin combination therapies, chloroquine in most non-falciparum and intravenous artesunate if any severity criteria. Human infections with intestinal protozoa are distributed worldwide with a high global morbid-mortality. They cause diarrhea and sometimes invasive disease, although most are asymptomatic. In our environment populations at higher risk are children, including adopted abroad, immune-suppressed, travelers, immigrants, people in contact with animals or who engage in oral-anal sex. Diagnostic microscopic examination has low sensitivity improving with antigen detection or molecular methods. Antiparasitic resistances are emerging lately. PMID:26832999

  4. Correlation between lead retention and intestinal pinocytosis in the suckling mouse

    SciTech Connect

    Keller, C.A.; Doherty, R.A.

    1980-01-01

    Young animals absorb and retain a greater fraction of an oral dose of lead than do adult animals. It has been proposed that pinocytotic activity in young animals is partially responsible for the increased lead retention and absorption. Radiolabeled lead (5 mg/kg) and polyvinylpyrrolidone (PVP, 50 mg/kg) were administered orally to 12-day-old suckling mice and to adult mice, and the uptake of lead and PVP was determined periodically during a 6-day interval. Intestinal tissue from the distal jejunum and ileum were found to contain the greatest quantities of both lead and PVP. Pretreatment of suckling mice with cortisone acetate resulted in decreased content of lead and PVP within tissue of the intestine, and decreased whole-body lead retention. Cortisone pretreatment produced lower lead concentrations in blood, brain, kidney, and liver. Lead and PVP uptake into intestinal tissue of adult mice was much less than uptake in suckling pups. Cortisone pretreatment of adult mice had no effect on whole-body lead retention or intestinal tissue content of lead or PVP.

  5. Delivery Rate Affects Uptake of a Fluorescent Glucose Analog in Murine Metastatic Breast Cancer

    PubMed Central

    Rajaram, Narasimhan; Frees, Amy E.; Fontanella, Andrew N.; Zhong, Jim; Hansen, Katherine; Dewhirst, Mark W.; Ramanujam, Nirmala

    2013-01-01

    We demonstrate an optical strategy using intravital microscopy of dorsal skin flap window chamber models to image glucose uptake and vascular oxygenation in vivo. Glucose uptake was imaged using a fluorescent glucose analog, 2-[N-(7-nitrobenz-2-oxa-1,3-diaxol-4-yl)amino]-2-deoxyglucose (2-NBDG). SO2 was imaged using the differential absorption properties of oxygenated [HbO2] and deoxygenated hemoglobin [dHb]. This study was carried out on two sibling murine mammary adenocarcinoma lines, 4T1 and 4T07. 2-NBDG uptake in the 4T1 tumors was lowest when rates of delivery and clearance were lowest, indicating perfusion-limited uptake in poorly oxygenated tumor regions. For increasing rates of delivery that were still lower than the glucose consumption rate (as measured in vitro), both 2-NBDG uptake and the clearance rate from the tumor increased. When the rate of delivery of 2-NBDG exceeded the glucose consumption rate, 2-NBDG uptake decreased with any further increase in rate of delivery, but the clearance rate continued to increase. This inflection point was not observed in the 4T07 tumors due to an absence of low delivery rates close to the glucose consumption rate. In the 4T07 tumors, 2-NBDG uptake increased with increasing rates of delivery at low rates of clearance. Our results demonstrate that 2-NBDG uptake in tumors is influenced by the rates of delivery and clearance of the tracer. The rates of delivery and clearance are, in turn, dependent on vascular oxygenation of the tumors. Knowledge of the kinetics of tracer uptake as well as vascular oxygenation is essential to make an informed assessment of glucose demand of a tumor. PMID:24204635

  6. Tissue engineering the small intestine.

    PubMed

    Spurrier, Ryan G; Grikscheit, Tracy C

    2013-04-01

    Short bowel syndrome (SBS) results from the loss of a highly specialized organ, the small intestine. SBS and its current treatments are associated with high morbidity and mortality. Production of tissue-engineered small intestine (TESI) from the patient's own cells could restore normal intestinal function via autologous transplantation. Improved understanding of intestinal stem cells and their niche have been coupled with advances in tissue engineering techniques. Originally described by Vacanti et al of Massachusetts General Hospital, TESI has been produced by in vivo implantation of organoid units. Organoid units are multicellular clusters of epithelium and mesenchyme that may be harvested from native intestine. These clusters are loaded onto a scaffold and implanted into the host omentum. The scaffold provides physical support that permits angiogenesis and vasculogenesis of the developing tissue. After a period of 4 weeks, histologic analyses confirm the similarity of TESI to native intestine. TESI contains a differentiated epithelium, mesenchyme, blood vessels, muscle, and nerve components. To date, similar experiments have proved successful in rat, mouse, and pig models. Additional experiments have shown clinical improvement and rescue of SBS rats after implantation of TESI. In comparison with the group that underwent massive enterectomy alone, rats that had surgical anastomosis of TESI to their shortened intestine showed improvement in postoperative weight gain and serum B12 values. Recently, organoid units have been harvested from human intestinal samples and successfully grown into TESI by using an immunodeficient mouse host. Current TESI production yields approximately 3 times the number of cells initially implanted, but improvements in the scaffold and blood supply are being developed in efforts to increase TESI size. Exciting new techniques in stem cell biology and directed cellular differentiation may generate additional sources of autologous intestinal

  7. OXYGEN TRANSPORT CERAMIC MEMBRANES

    SciTech Connect

    Dr. Sukumar Bandopadhyay; Dr. Nagendra Nagabhushana

    2000-10-01

    This is the third quarterly report on oxygen Transport Ceramic Membranes. In the following, the report describes the progress made by our university partners in Tasks 1 through 6, experimental apparatus that was designed and built for various tasks of this project, thermodynamic calculations, where applicable and work planned for the future. (Task 1) Design, fabricate and evaluate ceramic to metal seals based on graded ceramic powder/metal braze joints. (Task 2) Evaluate the effect of defect configuration on ceramic membrane conductivity and long term chemical and structural stability. (Task 3) Determine materials mechanical properties under conditions of high temperatures and reactive atmospheres. (Task 4) Evaluate phase stability and thermal expansion of candidate perovskite membranes and develop techniques to support these materials on porous metal structures. (Task 5) Assess the microstructure of membrane materials to evaluate the effects of vacancy-impurity association, defect clusters, and vacancy-dopant association on the membrane performance and stability. (Task 6) Measure kinetics of oxygen uptake and transport in ceramic membrane materials under commercially relevant conditions using isotope labeling techniques.

  8. Preliminary Design Report for Modeling of Hydrogen Uptake in Fuel Rod Cladding During Severe Accidents

    SciTech Connect

    Siefken, Larry James

    1999-02-01

    Preliminary designs are described for models of hydrogen and oxygen uptake in fuel rod cladding during severe accidents. Calculation of the uptake involves the modeling of seven processes: (1) diffusion of oxygen from the bulk gas into the boundary layer at the external cladding surface, (2) diffusion from the boundary layer into the oxide layer, (3) diffusion from the inner surface of the oxide layer into the metallic part of the cladding, (4) uptake of hydrogen in the event that the clad-ding oxide layer is dissolved in a steam-starved region, (5) embrittlement of cladding due to hydrogen uptake, (6) cracking of cladding during quenching due to its embrittlement and (7) release of hydrogen from the cladding after cracking of the cladding. An integral diffusion method is described for calculating the diffusion processes in the cladding. Experimental results are presented that show a rapid uptake of hydrogen in the event of dissolution of the oxide layer and a rapid release of hydrogen in the event of cracking of the oxide layer. These experimental results are used as a basis for calculating the rate of hydrogen uptake and the rate of hydrogen release. The uptake of hydrogen is limited to the equilibrium solubility calculated by applying Sievert's law. The uptake of hydrogen is an exothermic reaction that accelerates the heatup of a fuel rod. An embrittlement criteria is described that accounts for hydrogen and oxygen concentration and the extent of oxidation. A design is described for implementing the models for hydrogen and oxygen uptake and cladding embrittlement into the programming framework of the SCDAP/RELAP5 code. A test matrix is described for assessing the impact of the proposed models on the calculated behavior of fuel rods in severe accident conditions. This report is a revision and reissue of the report entitled; "Preliminary Design Report for Modeling of Hydrogen Uptake in Fuel Rod Cladding During Severe Accidents."

  9. Intestinal nematodes: biology and control.

    PubMed

    Epe, Christian

    2009-11-01

    A variety of nematodes occur in dogs and cats. Several nematode species inhabit the small and large intestines. Important species that live in the small intestine are roundworms of the genus Toxocara (T canis, T cati) and Toxascaris (ie, T leonina), and hookworms of the genus Ancylostoma (A caninum, A braziliense, A tubaeforme) or Uncinaria (U stenocephala). Parasites of the large intestine are nematodes of the genus Trichuris (ie, whipworms, T vulpis). After a comprehensive description of their life cycle and biology, which are indispensable for understanding and justifying their control, current recommendations for nematode control are presented and discussed thereafter. PMID:19932365

  10. Megacystis microcolon intestinal hypoperistalsis syndrome

    PubMed Central

    Hiradfar, Mehran; Shojaeian, Reza; Dehghanian, Paria; Hajian, Sara

    2013-01-01

    Megacystis microcolon intestinal hypoperistalsis syndrome (MMIHS) is a multisystemic disorder in which impaired intestinal motor activity causes recurrent symptoms of intestinal obstruction in the absence of mechanical occlusion, associated with bladder distention without distal obstruction of the urinary tract. MMIHS and prune belly syndrome may overlap in most of the clinical features and discrimination of these two entities is important because the prognosis, management and consulting with parents are completely different. MMIHS outcome is very poor and in this article we present two neonates with MMIHS that both died in a few days. PMID:23729700

  11. Megacystis microcolon intestinal hypoperistalsis syndrome.

    PubMed

    Hiradfar, Mehran; Shojaeian, Reza; Dehghanian, Paria; Hajian, Sara

    2013-01-01

    Megacystis microcolon intestinal hypoperistalsis syndrome (MMIHS) is a multisystemic disorder in which impaired intestinal motor activity causes recurrent symptoms of intestinal obstruction in the absence of mechanical occlusion, associated with bladder distention without distal obstruction of the urinary tract. MMIHS and prune belly syndrome may overlap in most of the clinical features and discrimination of these two entities is important because the prognosis, management and consulting with parents are completely different. MMIHS outcome is very poor and in this article we present two neonates with MMIHS that both died in a few days. PMID:23729700

  12. High tolerance of methanogens in granular sludge to oxygen

    SciTech Connect

    Kato, M.T.; Field, J.A.; Lettinga, G. . Dept. of Environmental Technology)

    1993-12-01

    This research assessed the effect of oxygen exposure on the methanogenic activity of anaerobic granular sludges. The toxicity of oxygen to acetoclastic methanogens in five different anaerobic granular sludges was determined in serum flasks with effective gas-to-liquid volumes of 4.65 to 1. The amount of oxygen that caused 50% inhibition of the methanogenic activity after 3 days of exposure ranged from 7% to 41% oxygen in the head space. These results indicate that methanogens located in granular sludge have a high tolerance for oxygen. The most important factor contributing to the tolerance was the oxygen consumption by facultative bacteria metabolizing biodegradable substrates. Uptake of oxygen by these bacteria creates anaerobic microenvironments where the methanogenic bacteria are protected. The results also indicate that methanogens in sludge consortia still have some tolerance to oxygen, even in the absence of facultative substrate for oxygen respiration.

  13. Small bowel preservation for intestinal transplantation: a review.

    PubMed

    Roskott, Anne Margot C; Nieuwenhuijs, Vincent B; Dijkstra, Gerard; Koudstaal, Lyan G; Leuvenink, Henri G D; Ploeg, Rutger J

    2011-02-01

    Intestinal transplantation has become the therapy of choice for patients with intestinal failure and life-threatening complications from total parenteral nutrition. Results, however, remain inferior as compared with other transplant types with the quality of the organ graft as the most important factor of outcome after transplantation. The intestine is extremely sensitive to ischemia. Unfortunately, a relatively long ischemic preservation period is inevitable. The current standard in organ preservation [cold storage (CS) with University of Wisconsin solution] was developed for kidney/liver preservation and is suboptimal for the intestinal graft despite good results for other organs. This review aimed at appraising the results from the use of previously applied and recently developed preservation solutions and techniques to identify key areas for improvement. As the studies available do not reveal the most effective method for intestinal preservation, an optimal strategy will result from a synergistic effect of different vital elements identified from a review of published material from the literature. A key factor is the composition of the solution using a low-viscosity solution to facilitate washout of blood, including amino acids to improve viability, impermeants and colloids to prevent edema, and buffer for pH-homeostasis. Optimizing conditions include a vascular flush before CS and luminal preservation. The most effective composition of the luminal solution and a practical, clinically applicable optimal technique are yet to reach finality. Short-duration oxygenated arterial and/or luminal perfusion have to be considered. Thus, a tailor-made approach to luminal preservation solution and technique need further investigation in transplant models and the human setting to develop the ultimate technique meeting the physiologic demands of the intestinal graft during preservation. PMID:21083772

  14. The impact of hypoxia on intestinal epithelial cell functions: consequences for invasion by bacterial pathogens.

    PubMed

    Zeitouni, Nathalie E; Chotikatum, Sucheera; von Köckritz-Blickwede, Maren; Naim, Hassan Y

    2016-12-01

    The maintenance of oxygen homeostasis in human tissues is mediated by several cellular adaptations in response to low-oxygen stress, called hypoxia. A decrease in tissue oxygen levels is initially counteracted by increasing local blood flow to overcome diminished oxygenation and avoid hypoxic stress. However, studies have shown that the physiological oxygen concentrations in several tissues are much lower than atmospheric (normoxic) conditions, and the oxygen supply is finely regulated in individual cell types. The gastrointestinal tract has been described to subsist in a state of physiologically low oxygen level and is thus depicted as a tissue in the state of constant low-grade inflammation. The intestinal epithelial cell layer plays a vital role in the immune response to inflammation and infections that occur within the intestinal tissue and is involved in many of the adaptation responses to hypoxic stress. This is especially relevant in the context of inflammatory disorders, such as inflammatory bowel disease (IBD). Therefore, this review aims to describe the intestinal epithelial cellular response to hypoxia and the consequences for host interactions with invading gastrointestinal bacterial pathogens. PMID:27002817

  15. Endothelin-mediated vasoconstriction in postischemic newborn intestine.

    PubMed

    Nankervis, C A; Schauer, G M; Miller, C E

    2000-10-01

    We previously suggested that the profound, sustained vasoconstriction noted in 3-day-old swine intestine after a moderate episode of ischemia-reperfusion (I/R) reflects the unmasking of underlying constrictor tone consequent to a loss of endothelium-derived nitric oxide (NO). In this study, we sought to determine whether endothelin-1 (ET-1) was the unmasked constrictor and whether selective loss of endothelial ET(B) receptors, which mediate NO-based vasodilation, participated in the hemodynamic consequences of I/R in newborn intestine. Studies were performed in innervated, autoperfused intestinal loops in 3- and 35-day-old swine. Selective blockade of ET(A) receptors with BQ-610 had no effect on hemodynamics under control conditions; however, when administered before and during I/R, BQ-610 significantly attenuated the post-I/R vasoconstriction and reduction in arteriovenous O(2) difference in the younger group. In 3-day-old intestine, reduction of intestinal O(2) uptake to a level similar to that noted after I/R by lowering tissue temperature had no effect on the response to BQ-610 or ET-1, indicating that the change in response to BQ-610 noted after I/R was not simply consequent to the reduction in tissue O(2) demand. In studies in mesenteric artery rings suspended in myographs, we observed a leftward shift in the dose-response curve for ET-1 after selective blockade of ET(B) receptors with BQ-788 in 3- but not 35-day-old swine. Rings exposed to I/R in vivo behaved in a manner similar to control rings treated with BQ-788 or endothelium-denuded non-I/R rings. PMID:11005754

  16. [Imaging of intestinal ischemia].

    PubMed

    Van Beers, B E; Danse, E; Hammer, F; Goffette, P

    2004-04-01

    Ischemic bowel disease includes acute and chronic mesenteric ischemia, and colon ischemia. Cross-sectional imaging, and more particularly computed tomography, has an increasing role in the detection of acute and chronic mesenteric ischemia. Vascular obstructions or stenoses and changes in the bowel wall can be observed. Functional information can be added with MRI by using sequences that are sensitive to oxygen saturation in the superior mesenteric vein. Arteriography remains the reference examination in patients with acute mesenteric ischemia. PMID:15184799

  17. Deuterium Uptake in Magnetic-Fusion Devices with Lithium-Conditioned Carbon Walls

    SciTech Connect

    Krstic, Predrag S.; Allain, J. P.; Taylor, C. N.; Dadras, J.; Morokuma, K.; Jakowski, J.; Allouche, A.; Skinner, C. H.

    2013-01-01

    Lithium wall conditioning has lowered hydrogenic recycling and dramatically improved plasma performance in many magnetic-fusion devices. In this Letter, we report quantum-classical atomistic simulations and laboratory experiments that elucidate the roles of lithium and oxygen in the uptake of hydrogen in amorphous carbon. Surprisingly, we show that lithium creates a high oxygen concentration on a carbon surface when bombarded by deuterium. Furthermore, surface oxygen, rather than lithium, plays the key role in trapping hydrogen.

  18. Intestinal Lipid Absorption and Lipoprotein Formation

    PubMed Central

    Hussain, M. Mahmood

    2014-01-01

    Purpose of review The purpose of this review is to summarize evidence for the presence of two pathways of lipid absorption and their regulation. Recent findings Lipid absorption involves hydrolysis of dietary fat in the lumen of the intestine followed by the uptake of hydrolyzed products by enterocytes. Lipids are re-synthesized in the endoplasmic reticulum and are either secreted with chylomicrons and high density lipoproteins or stored as cytoplasmic lipid droplets. Lipids in the droplets are hydrolyzed and are secreted at a later time. Secretion of lipids by the chylomicron and HDL pathways are critically dependent on MTP and ABCA1, respectively, and are regulated independently. Gene ablation studies showed that MTP function and chylomicron assembly is essential for the absorption of triglyceride and retinyl esters. Ablation of MTP abolishes triglyceride absorption and results in massive triglyceride accumulation in enterocytes. Although majority of phospholipid, cholesterol and vitamin E are absorbed through the chylomicron pathway, a significant amount of these lipids are also absorbed via the HDL pathway. Chylomicron assembly and secretion is increased by the enhanced availability of fatty acids, whereas HDL pathway is upregulated by LXR agonists. Intestinal insulin resistance increases chylomicron and might reduce HDL production. Summary Triglycerides are exclusively transported via the chylomicron pathway and this process is critically dependent on MTP. Besides chylomicrons, absorption of phospholipids, free cholesterol, retinol, and vitamin E also involves high density lipoproteins. These two pathways are complementary and are regulated independently. They may be targeted to lower lipid absorption in order to control hyperlipidemia, obesity, metabolic syndrome, steatosis, insulin resistance, atherosclerosis and other disorders. PMID:24751933

  19. Recombinant glucose uptake system

    DOEpatents

    Ingrahm, Lonnie O.; Snoep, Jacob L.; Arfman, Nico

    1997-01-01

    Recombinant organisms are disclosed that contain a pathway for glucose uptake other than the pathway normally utilized by the host cell. In particular, the host cell is one in which glucose transport into the cell normally is coupled to PEP production. This host cell is transformed so that it uses an alternative pathway for glucose transport that is not coupled to PEP production. In a preferred embodiment, the host cell is a bacterium other than Z. mobilis that has been transformed to contain the glf and glk genes of Z. mobilis. By uncoupling glucose transport into the cell from PEP utilization, more PEP is produced for synthesis of products of commercial importance from a given quantity of biomass supplied to the host cells.

  20. Vacuolar Ca(2+) uptake.

    PubMed

    Pittman, Jon K

    2011-08-01

    Calcium transporters that mediate the removal of Ca(2+) from the cytosol and into internal stores provide a critical role in regulating Ca(2+) signals following stimulus induction and in preventing calcium toxicity. The vacuole is a major calcium store in many organisms, particularly plants and fungi. Two main pathways facilitate the accumulation of Ca(2+) into vacuoles, Ca(2+)-ATPases and Ca(2+)/H(+) exchangers. Here I review the biochemical and regulatory features of these transporters that have been characterised in yeast an