Ebselen alters cellular oxidative status and induces endoplasmic reticulum stress in rat hippocampal astrocytes.

PubMed

Santofimia-Castaño, Patricia; Izquierdo-Alvarez, Alicia; de la Casa-Resino, Irene; Martinez-Ruiz, Antonio; Perez-Lopez, Marcos; Portilla, Juan C; Salido, Gines M; Gonzalez, Antonio

2016-05-16

Ebselen (2-phenyl-1,2-benzisoselenazol-3(2H)-one) is an organoselenium radical scavenger compound, which has strong antioxidant and anti-inflammatory effects. Because of its properties, it may be protective against injury to the nervous tissue. However, evidence suggests that its glutathione peroxidase activity could underlie certain deleterious actions on cell physiology. In this study we have analyzed the effect of ebselen on rat hippocampal astrocytes in culture. Cellular oxidative status, cytosolic free-Ca(2+) concentration ([Ca(2+)]c), setting of endoplasmic reticulum stress and phosphorylation of glial fibrillary acidic protein and major mitogen-activated protein kinases were analyzed. Our results show that ebselen induced a concentration-dependent increase in the generation of reactive oxygen species in the mitochondria. We observed a concentration-dependent increase in global cysteine oxidation and in the level of malondialdehyde in the presence of ebselen. We also detected increases in catalase, glutathione S-transferase and glutathione reductase activity. Ebselen also evoked a concentration-dependent increase in [Ca(2+)]c. Moreover, we observed a concentration-dependent increase in the phosphorylation of the unfolded protein response markers, eukaryotic translation initiation factor 2α and X-box binding protein 1. Finally, ebselen also induced an increase in the phosphorylation of glial fibrillary acidic protein, SAPK/JNK, p38 MAPK and p44/42 MAPK. Our results provide strong evidence that implicate endoplasmic reticulum stress and activation of crucial mitogen-activated protein kinases in an oxidative damage of cells in the presence of ebselen. The compound thus might exert deleterious actions on astrocyte physiology that could compromise their function. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Concentration Dependence of Pool Nucleate Boiling Heat Transfer Coefficients for R134a and Polyolester Oil System

NASA Astrophysics Data System (ADS)

Sato, Tomoaki; Takaishi, Yoshinori; Oguchi, Kosei

This paper presents experimental results of the concentration dependence of heat transfer coefficients for mixtures of R134a and polyolester (POE) oil under the conditions of pool nuc1eateboiling. The experiments are conducted by means of ah horizontal platinum wire at saturation tel11peraturesof 9, 19, and 29°C and at oil concentrations from 0 to 8 mass%. The present results show that the boiling heat transfer coefficient for the system concerned decreases with increasing oil concentration as a whole but increases slightly at a low oil concentration of about 4 mass%. A correlation equation is also given as a function of heat flux, temperature and oil concentration to reproduce the experimental boiling heat transfer coefficient within an uncertainly of about±15%.

Low concentrations of procaine and diethylaminoethanol reduce the excitability but not the action potential amplitude of hippocampal pyramidal cells.

PubMed

Butterworth, J F; Cole, L R

1990-10-01

To determine whether concentrations of diethylaminoethanol (DEAE) and procaine below those that reduce the amplitude of action potentials might alter the excitability of brain cells, a single microelectrode intracellular recording technique was used to measure firing threshold and action potential amplitude of pyramidal cells in rat hippocampal slices. At low concentrations of both DEAE (less than or equal to 5 mM) and procaine (less than or equal to 0.5 mM), firing threshold was significantly increased (P less than 0.01), whereas action potential spike amplitude was minimally altered. At higher concentrations, both drugs significantly decreased action potential spike amplitude (P less than 0.025) as well as increased firing threshold (P less than 0.001). Diethylaminoethanol tended to increase threshold relatively more than procaine, when drug concentrations that similarly reduced action potential amplitude were compared. All actions of DEAE and procaine were reversible. Inhibition of action potentials by DEAE and procaine was clearly concentration-dependent (P less than or equal to 0.015). Diethylaminoethanol effects on threshold were marginally concentration-dependent (P = 0.08); procaine did not demonstrate clear concentration-dependent effects (P = 0.33) over the concentrations tested in this study. These similar actions of procaine and DEAE on brain cells suggest a mechanism by which intravenous local anesthetics may contribute to the general anesthetic state. Moreover, it appears possible that procaine metabolism and DEAE accumulation may underlie the prolonged effects sometimes seen after intravenous procaine administration.

Oxycodone physical dependence and its oral self-administration in C57BL/6J mice.

PubMed

Enga, Rachel M; Jackson, Asti; Damaj, M Imad; Beardsley, Patrick M

2016-10-15

Abuse of prescription opioids, such as oxycodone, has markedly increased in recent decades. While oxycodone's antinociceptive effects have been detailed in several preclinical reports, surprisingly few preclinical reports have elaborated its abuse-related effects. This is particularly surprising given that oxycodone has been in clinical use since 1917. In a novel oral operant self-administration procedure, C57BL/6J mice were trained to self-administer water before introducing increasing concentrations of oxycodone (0.056-1.0mg/ml) under post-prandial conditions during daily, 3-h test sessions. As the concentration of oxycodone increased, the numbers of deliveries first increased, then decreased in an inverted U-shape fashion characteristic of the patterns of other drugs self-administered during limited access conditions. After post-prandial conditions were removed, self-administration at the highest concentration was maintained suggesting oral oxycodone served as a positive reinforcer. In other mice, using a novel regimen of physical dependence, mice were administered increasing doses of oxycodone (9.0-33.0mg/kg, s.c.) over 9 days, challenged with naloxone (0.1-10.0mg/kg, s.c.), and then observed for 30min. Naloxone dose-dependently increased the observed number of somatic signs of withdrawal, suggesting physical dependence of oxycodone was induced under this regimen. This is the first report demonstrating induction of oral operant self-administration of oxycodone and dose-dependent precipitations of oxycodone withdrawal in C57BL/6J mice. The use of oral operant self-administration as well as the novel physical dependence regimen provides useful approaches to further examine the abuse- and dependence-related effects of this highly abused prescription opioid. Copyright © 2016 Elsevier B.V. All rights reserved.

Influence of local meteorology and NO2 conditions on ground-level ozone concentrations in the eastern part of Texas, USA.

PubMed

Gorai, A K; Tuluri, F; Tchounwou, P B; Ambinakudige, S

2015-02-01

The influence of local climatic factors on ground-level ozone concentrations is an area of increasing interest to air quality management in regards to future climate change. This study presents an analysis on the role of temperature, wind speed, wind direction, and NO 2 level on ground-level ozone concentrations over the region of Eastern Texas, USA. Ozone concentrations at the ground level depend on the formation and dispersion processes. Formation process mainly depends on the precursor sources, whereas, the dispersion of ozone depends on meteorological factors. Study results showed that the spatial mean of ground-level ozone concentrations was highly dependent on the spatial mean of NO 2 concentrations. However, spatial distributions of NO 2 and ozone concentrations were not uniformed throughout the study period due to uneven wind speeds and wind directions. Wind speed and wind direction also played a significant role in the dispersion of ozone. Temperature profile in the area rarely had any effects on the ozone concentrations due to low spatial variations.

Influence of local meteorology and NO2 conditions on ground-level ozone concentrations in the eastern part of Texas, USA

PubMed Central

Gorai, A. K.; Tuluri, F.; Tchounwou, P. B.; Ambinakudige, S.

2014-01-01

The influence of local climatic factors on ground-level ozone concentrations is an area of increasing interest to air quality management in regards to future climate change. This study presents an analysis on the role of temperature, wind speed, wind direction, and NO2 level on ground-level ozone concentrations over the region of Eastern Texas, USA. Ozone concentrations at the ground level depend on the formation and dispersion processes. Formation process mainly depends on the precursor sources, whereas, the dispersion of ozone depends on meteorological factors. Study results showed that the spatial mean of ground-level ozone concentrations was highly dependent on the spatial mean of NO2 concentrations. However, spatial distributions of NO2 and ozone concentrations were not uniformed throughout the study period due to uneven wind speeds and wind directions. Wind speed and wind direction also played a significant role in the dispersion of ozone. Temperature profile in the area rarely had any effects on the ozone concentrations due to low spatial variations. PMID:25755687

Effect of pH and glucose on cultured human peritoneal mesothelial cells.

PubMed

Shao, J C; Yorioka, N; Nishida, Y; Yamakido, M

1999-08-01

We investigated the effects of various pH and glucose concentrations on the growth of human peritoneal mesothelial cells and on coagulation and fibrinolytic factors. Cells were cultured at various pH values in Ham's F-12 medium containing 1.0% foetal calf serum and supplemented with D-glucose or D-mannitol at various concentrations. After 4-48 h, cell proliferation and 3H-thymidine incorporation were determined. Coagulation and fibrinolytic factors were measured after 48 h. Glucose caused concentration-dependent inhibition of cell growth at all pH values, but the deleterious effect of low pH on cell proliferation was faster and stronger than that of high glucose. At a similar osmolality, mannitol caused less inhibition of cell proliferation than glucose. There was a glucose concentration-dependent increase of thrombin-antithrombin III complex production at all pH values. At pH 5.2, tissue-type plasminogen activator production was far lower than at higher pH values, and production of the plasminogen activator inhibitor showed a glucose concentration-dependent increase. At pH 6.5 or 7.3, however, the plasminogen activator inhibitor production decreased and tissue-type plasminogen activator production increased in a glucose concentration-dependent manner. Low pH and/or high glucose culture medium had an inhibitory effect on peritoneal mesothelial cells, with the effect of high glucose being partially related to hyperosmolality. These cells may modulate peritoneal coagulant and fibrinolytic activity, with the balance between coagulation and fibrinolysis being disturbed by low pH and/or high glucose.

Concentration dependent survival and neural differentiation of murine embryonic stem cells cultured on polyethylene glycol dimethacrylate hydrogels possessing a continuous concentration gradient of n-cadherin derived peptide His-Ala-Val-Asp-Lle.

PubMed

Lim, Hyun Ju; Mosley, Matthew C; Kurosu, Yuki; Smith Callahan, Laura A

2017-07-01

N-cadherin cell-cell signaling plays a key role in the structure and function of the nervous system. However, few studies have incorporated bioactive signaling from n-cadherin into tissue engineering matrices. The present study uses a continuous gradient approach in polyethylene glycol dimethacrylate hydrogels to identify concentration dependent effects of n-cadherin peptide, His-Ala-Val-Asp-Lle (HAVDI), on murine embryonic stem cell survival and neural differentiation. The n-cadherin peptide was found to affect the expression of pluripotency marker, alkaline phosphatase, in murine embryonic stem cells cultured on n-cadherin peptide containing hydrogels in a concentration dependent manner. Increasing n-cadherin peptide concentrations in the hydrogels elicited a biphasic response in neurite extension length and mRNA expression of neural differentiation marker, neuron-specific class III β-tubulin, in murine embryonic stem cells cultured on the hydrogels. High concentrations of n-cadherin peptide in the hydrogels were found to increase the expression of apoptotic marker, caspase 3/7, in murine embryonic stem cells compared to that of murine embryonic stem cell cultures on hydrogels containing lower concentrations of n-cadherin peptide. Increasing the n-cadherin peptide concentration in the hydrogels facilitated greater survival of murine embryonic stem cells exposed to increasing oxidative stress caused by hydrogen peroxide exposure. The combinatorial approach presented in this work demonstrates concentration dependent effects of n-cadherin signaling on mouse embryonic stem cell behavior, underscoring the need for the greater use of systematic approaches in tissue engineering matrix design in order to understand and optimize bioactive signaling in the matrix for tissue formation. Single cell encapsulation is common in tissue engineering matrices. This eliminates cellular access to cell-cell signaling. N-cadherin, a cell-cell signaling molecule, plays a vital role in the development of neural tissues, but has not been well studied as a bioactive signaling element in neural tissue engineering matrices. The present study uses a systematic continuous gradient approach to identify concentration dependent effects of n-cadherin derived peptide, HAVDI, on the survival and neural differentiation of murine embryonic stem cells. This work underscores the need for greater use to combinatorial strategies to understand the effect complex bioactive signaling, such as n-cadherin, and the need to optimize the concentration of such bioactive signaling within tissue engineering matrices for maximal cellular response. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Regulation of renal urea transport by vasopressin.

PubMed

Sands, Jeff M; Blount, Mitsi A; Klein, Janet D

2011-01-01

Terrestrial life would be miserable without the ability to concentrate urine. Production of concentrated urine requires complex interactions among the nephron segments and vasculature in the kidney medulla. In addition to water channels (aquaporins) and sodium transporters, urea transporters are critically important to the theories proposed to explain the physiologic processes occurring when urine is concentrated. Vasopressin (anti-diuretic hormone) is the key hormone regulating the production of concentrated urine. Vasopressin rapidly increases water and urea transport in the terminal inner medullary collecting duct (IMCD). Vasopressin rapidly increases urea permeability in the IMCD through increases in phosphorylation and apical plasma-membrane accumulation of the urea transporter A1 (UT-A1). Vasopressin acts through two cAMP-dependent signaling pathways in the IMCD: protein kinase A and exchange protein activated by cAMP Epac. Protein kinase A phosphorylates UT-A1 at serines 486 and 499. In summary, vasopressin regulates urea transport acutely by increasing UT-A1 phosphorylation and the apical plasma-membrane accumulation of UT-A1 through two cAMP-dependent pathways.

Soil Nitrification and N2O Production: the connection with N concentration and Soil Water Content

NASA Astrophysics Data System (ADS)

Zhu-Barker, X.; Horwath, W. R.

2016-12-01

The development of mitigation strategies to reduce nitrous oxide (N2O) emission from soils is dependent on explicating the biophysical factors affecting different N2O production pathways. Ammonia oxidation and heterotrophic denitrification are the main pathways of N2O production, depending on soil conditions such as soil moisture content, oxygen (O2) content and N substrate. Many researchers have reported that N2O production increased as substrate concentration and soil moisture content increased. However, less understood is how N fertilizer concentration and moisture content interact to affect N2O production pathways. To investigate interaction and its effect on O2 consumption, we incubated three agricultural soils (clay, sandy loam, and peat) with different concentrations of (NH4)2SO4 (0-1000 µg N g-1) under 50 %, 75%, and 100% of water holding capacity. All treatments received 15N -KNO3 to bring the concentrations of NO3-_N in soils to 50 mg kg-1 soil and the NO3- pool to an enrichment of 10 atom% 15N. In all soils, the total amount of O2 consumption and N2O production increased as soil ammonical N concentration increased. The increased soil moisture significantly promoted N2O production in sandy loam and clay loam soils, compared to the peat soil. These results indicate that N2O production increased as substrate concentration increased likely due to the onset of O2 limitation caused by ammonia oxidation.

pH-dependent interaction and resultant structures of silica nanoparticles and lysozyme protein.

PubMed

Kumar, Sugam; Aswal, Vinod K; Callow, P

2014-02-18

Small-angle neutron scattering (SANS) and UV-visible spectroscopy studies have been carried out to examine pH-dependent interactions and resultant structures of oppositely charged silica nanoparticles and lysozyme protein in aqueous solution. The measurements were carried out at fixed concentration (1 wt %) of three differently sized silica nanoparticles (8, 16, and 26 nm) over a wide concentration range of protein (0-10 wt %) at three different pH values (5, 7, and 9). The adsorption curve as obtained by UV-visible spectroscopy shows exponential behavior of protein adsorption on nanoparticles. The electrostatic interaction enhanced by the decrease in the pH between the nanoparticle and protein (isoelectric point ∼11.4) increases the adsorption coefficient on nanoparticles but decreases the overall amount protein adsorbed whereas the opposite behavior is observed with increasing nanoparticle size. The adsorption of protein leads to the protein-mediated aggregation of nanoparticles. These aggregates are found to be surface fractals at pH 5 and change to mass fractals with increasing pH and/or decreasing nanoparticle size. Two different concentration regimes of interaction of nanoparticles with protein have been observed: (i) unaggregated nanoparticles coexisting with aggregated nanoparticles at low protein concentrations and (ii) free protein coexisting with aggregated nanoparticles at higher protein concentrations. These concentration regimes are found to be strongly dependent on both the pH and nanoparticle size.

Estimated effects of temperature on secondary organic aerosol concentrations.

PubMed

Sheehan, P E; Bowman, F M

2001-06-01

The temperature-dependence of secondary organic aerosol (SOA) concentrations is explored using an absorptive-partitioning model under a variety of simplified atmospheric conditions. Experimentally determined partitioning parameters for high yield aromatics are used. Variation of vapor pressures with temperature is assumed to be the main source of temperature effects. Known semivolatile products are used to define a modeling range of vaporization enthalpy of 10-25 kcal/mol-1. The effect of diurnal temperature variations on model predictions for various assumed vaporization enthalpies, precursor emission rates, and primary organic concentrations is explored. Results show that temperature is likely to have a significant influence on SOA partitioning and resulting SOA concentrations. A 10 degrees C decrease in temperature is estimated to increase SOA yields by 20-150%, depending on the assumed vaporization enthalpy. In model simulations, high daytime temperatures tend to reduce SOA concentrations by 16-24%, while cooler nighttime temperatures lead to a 22-34% increase, compared to constant temperature conditions. Results suggest that currently available constant temperature partitioning coefficients do not adequately represent atmospheric SOA partitioning behavior. Air quality models neglecting the temperature dependence of partitioning are expected to underpredict peak SOA concentrations as well as mistime their occurrence.

Characterization and modelling of the boron-oxygen defect activation in compensated n-type silicon

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

Schön, J.; Niewelt, T.; Broisch, J.

2015-12-28

A study of the activation of the light-induced degradation in compensated n-type Czochralski grown silicon is presented. A kinetic model is established that verifies the existence of both the fast and the slow components known from p-type and proves the quadratic dependence of the defect generation rates of both defects on the hole concentration. The model allows for the description of lifetime degradation kinetics in compensated n-type silicon under various intensities and is in accordance with the findings for p-type silicon. We found that the final concentrations of the slow defect component in compensated n-type silicon only depend on themore » interstitial oxygen concentration and on neither the boron concentration nor the equilibrium electron concentration n{sub 0}. The final concentrations of the fast defect component slightly increase with increasing boron concentration. The results on n-type silicon give new insight to the origin of the BO defect and question the existing models for the defect composition.« less

Ultrasteep Voltage Dependence in a Membrane Channel

NASA Astrophysics Data System (ADS)

Mangan, Patrick S.; Colombini, Marco

1987-07-01

A mechanism for regulating voltage-gated channels is presented. The treatment amplifies the effect of the applied membrane potential resulting in a dramatic increase in the channel's voltage dependence. Addition of a large polyvalent anion to the medium bathing a phospholipid bilayer containing the voltage-dependent channel from the mitochondrial outer membrane, VDAC, induced up to a 12-fold increase in the channel's voltage sensitivity. The highest polyvalent anion concentration tested resulted in an e-fold conductance change for a 0.36-mV change in membrane potential. On the low end, a concentration of 2 μ M resulted in a 50% increase in VDAC voltage dependence. A mechanism based on polyvalent anion accumulation in the access resistance region at the mouth of the pore is consistent with all findings. Perhaps the voltage dependence of voltage-gated channels is amplified in vivo by polyvalent ions. If so, the control of excitable phenomena may be under much finer regulation than that provided by membrane potential alone.

Dual regulation of Ca2+-dependent glutamate release from astrocytes: vesicular glutamate transporters and cytosolic glutamate levels.

PubMed

Ni, Yingchun; Parpura, Vladimir

2009-09-01

Vesicular glutamate transporters (VGLUTs) are responsible for vesicular glutamate storage and exocytotic glutamate release in neurons and astrocytes. Here, we selectively and efficiently overexpressed individual VGLUT proteins (VGLUT1, 2, or 3) in solitary astrocytes and studied their effects on mechanical stimulation-induced Ca2+-dependent glutamate release. Neither VGLUT1 nor VGLUT2 overexpression changed the amount of glutamate release, whereas overexpression of VGLUT3 significantly enhanced Ca2+-dependent glutamate release from astrocytes. None of the VGLUT overexpression affected mechanically induced intracellular Ca2+ increase. Inhibition of glutamine synthetase activity by L-methionine sulfoximine in astrocytes, which leads to increased cytosolic glutamate concentration, greatly increased their mechanically induced Ca2+-dependent glutamate release, without affecting intracellular Ca2+ dynamics. Taken together, these data indicate that both VGLUT3 and the cytosolic concentration of glutamate are key limiting factors in regulating the Ca2+-dependent release of glutamate from astrocytes.

Comprehensive analysis of structure and temperature, frequency and concentration-dependent dielectric properties of lithium-substituted cobalt ferrites (Li x Co1- x Fe2O4)

NASA Astrophysics Data System (ADS)

Anjum, Safia; Nisa, Mehru; Sabah, Aneeqa; Rafique, M. S.; Zia, Rehana

2017-08-01

This paper has been dedicated to the synthesis and characterization of a series of lithium-substituted cobalt ferrites Li x Co1- x Fe2O4 ( x = 0, 0.2, 0.4, 0.6, 0.8, 1). These samples have been prepared using simple ball milling machine through powder metallurgy route. The structural analysis is carried out using X-ray diffractometer and their 3D vitalization is simulated using diamond software. The frequency and temperature-dependent dielectric properties of prepared samples have been measured using inductor capacitor resistor (LCR) meter. The structural analysis confirms that all the prepared samples have inverse cubic spinel structure. It is also revealed that the crystallite size and lattice parameter decrease with the increasing concentration of lithium (Li+1) ions, it is due to the smaller ionic radii of lithium ions. The comprehensive analysis of frequency, concentration and temperature-dependent dielectric properties of prepared samples is described in this paper. It is observed that the dielectric constant and tangent loss have decreased and conductivity increased as the frequency increases. It is also revealed that the dielectric constant, tangent loss and AC conductivity increase as the concentration of lithium increases due to its lower electronegativity value. Temperature plays a vital role in enhancing the dielectric constant, tangent loss and AC conductivity because the mobility of ions increases as the temperature increases.

Oxygen Inhibition of Photosynthesis and Stimulation of Photorespiration in Soybean Leaf Cells

PubMed Central

Servaites, Jerome C.; Ogren, William L.

1978-01-01

The occurrence of photorespiration in soybean (Glycine max [L.] Merr.) leaf cells was demonstrated by the presence of an O2-dependent CO2 compensation concentration, a nonlinear time course for photosynthetic 14CO2 uptake at low CO2 and high O2 concentrations, and an O2 stimulation of glycine and serine synthesis which was reversed by high CO2 concentration. The compensation concentration was a linear function of O2 concentration and increased as temperature increased. At atmospheric CO2 concentration, 21% O2 inhibited photosynthesis at 25 C by 27%. Oxygen inhibition of photosynthesis was competitive with respect to CO2 and increased with increasing temperature. The Km (CO2) of photosynthesis was also temperature-dependent, increasing from 12 μm CO2 at 15 C to 38 μm at 35 C. In contrast, the Ki (O2) was similar at all temperatures. Oxygen inhibition of photosynthesis was independent of irradiance except at 10 mm bicarbonate and 100% O2, where inhibition decreased with increasing irradiance up to the point of light saturation of photosynthesis. Concomitant with increasing O2 inhibition of photosynthesis was an increased incorporation of carbon into glycine and serine, intermediates of the photorespiratory pathway, and a decreased incorporation into starch. The effects of CO2 and O2 concentration and temperature on soybean cell photosynthesis and photorespiration provide further evidence that these processes are regulated by the kinetic properties of ribulose-1,5-diphosphate carboxylase with respect to CO2 and O2. PMID:16660238

DIFFERENT CONCENTRATIONS OF SIJUNZI DECOCTION INHIBIT PROLIFERATION AND INDUCE APOPTOSIS OF HUMAN GASTRIC CANCER SGC-7901 SIDE POPULATION.

PubMed

Qian, Jun; Li, Jing; Jia, Jianguang; Jin, Xin; Yu, Dajun; Guo, Chenxu; Xie, Bo; Qian, Liyu

2016-01-01

Sijunzi Decoction (SD) is a traditional Chinese medicine which is composed of Ginseng, Atractylodes, Poria and Licorice. It is one of the commonly used Chinese traditional medicines that showed anti-gastric cancer activity in clinical studies. Previous evidence demonstrated SD parties (Ginseng, Atractylodes, Poria, Licorice) can inhibit proliferation and induced apoptosis for gastric cancer cell. In order to further investigate the anticancer effect of SD in gastric cancer, we observed the effects of different concentrations of SD on proliferation and apoptosis of Side Population Cells (SP) of human gastric cancer SGC-7901. SGC-7901 SP and Non- Side Population Cells (NSP) were sorted through flow cytometry; to detect the changes of proliferation of SP and NSP before and after the intervention of serum containing different concentrations of SD using cck-8 method; to detect the changes of cell cycle and apoptosis of SP and NSP before and after the intervention of serum containing different concentrations of SD through flow cytometry; to detect the effects of serum containing different concentrations of SD on apoptosis-related proteins Bax and Bcl-2 of SP and NSP before and after the intervention by western-blot. It was found that different concentrations of SD serum treatments inhibited cell proliferation in a time-dependent and concentration-dependent manner. Compared with the control group (normal saline serum treatment), there were increase in G1/G0 phase population of SP and NSP, and decrease in G2/M and S phase population ( P <0.05). Meanwhile, we found G1/G0 arrest induced by different concentrations of SD serum which was followed by apoptosis in a time-dependent and concentration-dependent manner. The apoptosis rate of SD serum treatment group was higher than the control group ( P <0.05), the apoptosis rate of 48 h treatment was higher than 24 h treatment ( P <0.05), and as the SD serum concentration increases, apoptosis rate is higher and higher ( P <0.05). The expression of Bax protein of SP and NSP was higher than the control group in a time-dependent and concentration dependent manner. The expression of Bcl-2 protein of SP and NSP was lower than the control group in a time-dependent and concentration- dependent manner. With the increase of SD serum concentrations, SD can gradually inhibits the proliferation of SP of SGC-7901 cell lines through G1/G0 phase arrest and followed by apoptosis which involves the up-regulation of Bax and the down-regulation of Bcl-2. List of Abbreviations: (SD) Sijunzi Decoction, (SP) side population, (NSP) non-side population, (Control) normal saline serum group, (L) low concentration SD serum group, (N) normal concentration SD serum group, (H) high concentration SD serum group, (ABCG-2) Adenosine triphosphate Binding Cassette super family G member-2 of transport protein, (Bcl-2) B-cell lymphoma 2, (BAX) Bcl-2 Associated X Protein, (FBS) Fetal bovine serum, (PBS) Phosphate buffer solution, (CCK-8) Cell Counting Kit-8 reagent, (AV) Annexin V-FITC, (PI) Propidium iodide, (EDTA) Ethylene Diamine Tetraacetic Acid, (PMSF) Phenylmethanesulfonyl fluoride, (RIPA) Radio Immunoprecipitation Assay, (PVDF) Poly (vinylidene fluoride), (TBST) Tris-buffered saline containing Tween-20.

Miscibility and crystallization behavior of poly (3-hydroxybutyrate) and poly (ethylene glycol) blends studied by positron annihilation spectroscopy

NASA Astrophysics Data System (ADS)

Abdel-Hady, E. E.; Abdel-Hamed, M. O.; Hammam, A. M.

2011-01-01

Positron annihilation Lifetime (PAL) spectroscopy has been used to study the effect of PEG concentrations on the free volume properties of PHB. The data revealed that the ortho-positronium (o-Ps) lifetime τPs increases with 20% increase in concentration, decrease as the concentration increases to 40%, then rapid increase at 50% concentration of PEG. The o-Ps intensity, I3, shows a linear dependence as the concentration increases with a discontinuity at 20% concentration of PEG. Furthermore, the results presented and discussed in this work show that the PHB and PEG are miscible up to 40% of PEG but greater than 40%, the blend is immiscible. In addition, the mechanical properties of PHB are well improved by the addition of PEG with a low concentration up to 20%, while at higher concentration the blend becomes waxy.

Two-stage concentrating systems for pumping of solar lasers

NASA Astrophysics Data System (ADS)

Klichev, Sh.; Bakhramov, S.; Abdurakhmanov, A.; Fazilov, A.; Payziyev, Sh.; Ismanjanov, A.; Bokoev, K.; Dudko, J.; Klichev, Z.

2008-02-01

One of the ways to increase the concentrating ability of solar concentrators used for pumping of lasers is an additional concentration of a sunlight by a secondary concentrator allocated in a focal area of the primary concentrator. Limiting concentrations of those compound systems on the basis of non-imaging optics have been received by Winston. However more detailed calculations on the basis of irradiance integral are necessary for designing and practical realization of such systems. It is especially important for the systems including generally compound of two secondary concentrators. The full design procedure for concentration by systems of type compound parabolic concentrator or Winston concentrator (focon) and a cone concentrator is developed in the work in view of real distribution of brightness on a solar disk and discrepancies of primary concentrator geometry. The generalized dependences of efficiency of compound systems for the maximal and mean concentration in a focal plane of the primary paraboloidal concentrator depending on its disclosing angle U 0 and discrepancies of geometry are received. It is shown, that focon only up to U 0 < 30° is more effective, than the cone and further their efficiencies are identical. It is shown, that secondary concentrator allows to increase the pumping efficiency not less, than 30%.

Nonlinear photoacoustic spectroscopy of hemoglobin

PubMed Central

Danielli, Amos; Maslov, Konstantin; Favazza, Christopher P.; Xia, Jun; Wang, Lihong V.

2015-01-01

As light intensity increases in photoacoustic imaging, the saturation of optical absorption and the temperature dependence of the thermal expansion coefficient result in a measurable nonlinear dependence of the photoacoustic (PA) signal on the excitation pulse fluence. Here, under controlled conditions, we investigate the intensity-dependent photoacoustic signals from oxygenated and deoxygenated hemoglobin at varied optical wavelengths and molecular concentrations. The wavelength and concentration dependencies of the nonlinear PA spectrum are found to be significantly greater in oxygenated hemoglobin than in deoxygenated hemoglobin. These effects are further influenced by the hemoglobin concentration. These nonlinear phenomena provide insights into applications of photoacoustics, such as measurements of average inter-molecular distances on a nm scale or with a tuned selection of wavelengths, a more accurate quantitative PA tomography. PMID:26045627

Nonlinear photoacoustic spectroscopy of hemoglobin.

PubMed

Danielli, Amos; Maslov, Konstantin; Favazza, Christopher P; Xia, Jun; Wang, Lihong V

2015-05-18

As light intensity increases in photoacoustic imaging, the saturation of optical absorption and the temperature dependence of the thermal expansion coefficient result in a measurable nonlinear dependence of the photoacoustic (PA) signal on the excitation pulse fluence. Here, under controlled conditions, we investigate the intensity-dependent photoacoustic signals from oxygenated and deoxygenated hemoglobin at varied optical wavelengths and molecular concentrations. The wavelength and concentration dependencies of the nonlinear PA spectrum are found to be significantly greater in oxygenated hemoglobin than in deoxygenated hemoglobin. These effects are further influenced by the hemoglobin concentration. These nonlinear phenomena provide insights into applications of photoacoustics, such as measurements of average inter-molecular distances on a nm scale or with a tuned selection of wavelengths, a more accurate quantitative PA tomography.

Salt Inactivates Endothelial Nitric Oxide Synthase in Endothelial Cells12

PubMed Central

Li, Juan; White, James; Guo, Ling; Zhao, Xiaomin; Wang, Jiafu; Smart, Eric J.; Li, Xiang-An

2009-01-01

There is a 1–4 mmol/L rise in plasma sodium concentrations in individuals with high salt intake and in patients with essential hypertension. In this study, we used 3 independent assays to determine whether such a small increase in sodium concentrations per se alters endothelial nitric oxide synthase (eNOS) function and contributes to hypertension. By directly measuring NOS activity in living bovine aortic endothelial cells, we demonstrated that a 5-mmol/L increase in salt concentration (from 137 to 142 mmol/L) caused a 25% decrease in NOS activity. Importantly, the decrease in NOS activity was in a salt concentration-dependent manner. The NOS activity was decreased by 25, 45, and 70%, with the increase of 5, 10, and 20 mmol/L of NaCl, respectively. Using Chinese hamster ovary cells stably expressing eNOS, we confirmed the inhibitory effects of salt on eNOS activity. The eNOS activity was unaffected in the presence of equal milliosmol of mannitol, which excludes an osmotic effect. Using an ex vivo aortic angiogenesis assay, we demonstrated that salt attenuated the nitric oxide (NO)-dependent proliferation of endothelial cells. By directly monitoring blood pressure changes in response to salt infusion, we found that in vivo infusion of salt induced an acute increase in blood pressure in a salt concentration-dependent manner. In conclusion, our findings demonstrated that eNOS is sensitive to changes in salt concentration. A 5-mmol/L rise in salt concentration, within the range observed in essential hypertension patients or in individuals with high salt intake, could significantly suppress eNOS activity. This salt-induced reduction in NO generation in endothelial cells may contribute to the development of hypertension. PMID:19176751

Salt inactivates endothelial nitric oxide synthase in endothelial cells.

PubMed

Li, Juan; White, James; Guo, Ling; Zhao, Xiaomin; Wang, Jiafu; Smart, Eric J; Li, Xiang-An

2009-03-01

There is a 1-4 mmol/L rise in plasma sodium concentrations in individuals with high salt intake and in patients with essential hypertension. In this study, we used 3 independent assays to determine whether such a small increase in sodium concentrations per se alters endothelial nitric oxide synthase (eNOS) function and contributes to hypertension. By directly measuring NOS activity in living bovine aortic endothelial cells, we demonstrated that a 5-mmol/L increase in salt concentration (from 137 to 142 mmol/L) caused a 25% decrease in NOS activity. Importantly, the decrease in NOS activity was in a salt concentration-dependent manner. The NOS activity was decreased by 25, 45, and 70%, with the increase of 5, 10, and 20 mmol/L of NaCl, respectively. Using Chinese hamster ovary cells stably expressing eNOS, we confirmed the inhibitory effects of salt on eNOS activity. The eNOS activity was unaffected in the presence of equal milliosmol of mannitol, which excludes an osmotic effect. Using an ex vivo aortic angiogenesis assay, we demonstrated that salt attenuated the nitric oxide (NO)-dependent proliferation of endothelial cells. By directly monitoring blood pressure changes in response to salt infusion, we found that in vivo infusion of salt induced an acute increase in blood pressure in a salt concentration-dependent manner. In conclusion, our findings demonstrated that eNOS is sensitive to changes in salt concentration. A 5-mmol/L rise in salt concentration, within the range observed in essential hypertension patients or in individuals with high salt intake, could significantly suppress eNOS activity. This salt-induced reduction in NO generation in endothelial cells may contribute to the development of hypertension.

/sup 3/H-PAF-acether displacement and inhibition of binding in intact human platelets by BN 52021

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

Korth, R.; Le Couedic, J.P.; Benveniste, J.

1986-03-05

Intact washed human platelets incubated at 20/sup 0/C in Tyrode's buffer containing 0.25% (w/v) bovine serum albumin bound /sup 3/H paf-acether in a concentration (0-6.5 nM) and time (0-60 min) dependent manner (n=3). BN 52021 (60 ..mu..M) a chemically defined extract from Ginkgo biloba inhibited the binding of increasing concentrations of /sup 3/H paf-acether. Calculated differences between /sup 3/H paf-acether binding in the presence or absence of BN 52021 (60 ..mu..M) reached nearly a plateau in concentrations higher than 0.65 nM /sup 3/H paf-acether. Increasing concentrations of BN 52021 (0-60 ..mu..M) as well as of unlabelled paf-acether (0-50 nM) preventedmore » within 15 min /sup 3/H paf-acether binding (0.65 nM) to platelets in a concentration-dependent way. Increasing BN 52021 concentrations (0-60 ..mu..M) also displaced platelet-bound /sup 3/H paf-acether (0.65 nM) in a concentration-dependent way. Displacement increased with the time length of platelet incubation with BN 52021 and reached a plateau at 15 min. Platelet-bound /sup 3/H paf-acether displacement of 28.3 +/- 6.3%, 31.1 +/- 4.0% and 26.7 +/- 5.6% was observed using 50 nM unlabelled paf-acether, 60 ..mu..M BN 52021 or both substances together (vs 4.3 +/- 7.2% for vehicle alone). No degradation of /sup 3/H paf-acether occurred as assessed by high pressure liquid chromatography. These results demonstrate that BN 52021 competes directly with paf-acether binding sites on human platelets.« less

Strong composition-dependent variation of MCs + calibration factors in TiO x and GeO x ( x ≤ 2) films

NASA Astrophysics Data System (ADS)

Gnaser, Hubert; Le, Yongkang; Su, Weifeng

2006-07-01

The emission of MCs + secondary ions (M designates the analyte species) from TiO x (0.2 ≤ x ≤ 2) and GeO x (0.001 ≤ x ≤ 0.8) films under Cs + bombardment was examined. The relative calibration factors of OCs +/TiCs + and OCs +/GeCs + were determined and were found to depend pronouncedly on the O/Ti and O/Ge atomic concentration ratios. Specifically, with increasing oxygen content OCs + ions form much more efficiently (as compared to TiCs + or GeCs + ions), an enhancement amounting to more than a factor of 10 for the highest oxygen concentrations. Concurrently, the formation of TiOCs + or GeOCs + ions increases drastically. For both oxide systems, an empirical relation for the oxygen-concentration dependence of the relative calibration factors could be established.

Direction dependence of displacement time for two-fluid electroosmotic flow.

PubMed

Lim, Chun Yee; Lam, Yee Cheong

2012-03-01

Electroosmotic flow that involves one fluid displacing another fluid is commonly encountered in various microfludic applications and experiments, for example, current monitoring technique to determine zeta potential of microchannel. There is experimentally observed anomaly in such flow, namely, the displacement time is flow direction dependent, i.e., it depends if it is a high concentration fluid displacing a low concentration fluid, or vice versa. Thus, this investigation focuses on the displacement flow of two fluids with various concentration differences. The displacement time was determined experimentally with current monitoring method. It is concluded that the time required for a high concentration solution to displace a low concentration solution is smaller than the time required for a low concentration solution to displace a high concentration solution. The percentage displacement time difference increases with increasing concentration difference and independent of the length or width of the channel and the voltage applied. Hitherto, no theoretical analysis or numerical simulation has been conducted to explain this phenomenon. A numerical model based on finite element method was developed to explain the experimental observations. Simulations showed that the velocity profile and ion distribution deviate significantly from a single fluid electroosmotic flow. The distortion of ion distribution near the electrical double layer is responsible for the displacement time difference for the two different flow directions. The trends obtained from simulations agree with the experimental findings.

Direction dependence of displacement time for two-fluid electroosmotic flow

PubMed Central

Lim, Chun Yee; Lam, Yee Cheong

2012-01-01

Electroosmotic flow that involves one fluid displacing another fluid is commonly encountered in various microfludic applications and experiments, for example, current monitoring technique to determine zeta potential of microchannel. There is experimentally observed anomaly in such flow, namely, the displacement time is flow direction dependent, i.e., it depends if it is a high concentration fluid displacing a low concentration fluid, or vice versa. Thus, this investigation focuses on the displacement flow of two fluids with various concentration differences. The displacement time was determined experimentally with current monitoring method. It is concluded that the time required for a high concentration solution to displace a low concentration solution is smaller than the time required for a low concentration solution to displace a high concentration solution. The percentage displacement time difference increases with increasing concentration difference and independent of the length or width of the channel and the voltage applied. Hitherto, no theoretical analysis or numerical simulation has been conducted to explain this phenomenon. A numerical model based on finite element method was developed to explain the experimental observations. Simulations showed that the velocity profile and ion distribution deviate significantly from a single fluid electroosmotic flow. The distortion of ion distribution near the electrical double layer is responsible for the displacement time difference for the two different flow directions. The trends obtained from simulations agree with the experimental findings. PMID:22662083

Gastric inhibitory polypeptide-dependent cortisol hypersecretion--a new cause of Cushing's syndrome.

PubMed

Lacroix, A; Bolté, E; Tremblay, J; Dupré, J; Poitras, P; Fournier, H; Garon, J; Garrel, D; Bayard, F; Taillefer, R

1992-10-01

Corticotropin-independent nodular adrenal hyperplasia is a rare cause of Cushing's syndrome, and the factors responsible for the adrenal hyperplasia are not known. We studied a 48-year-old woman with Cushing's syndrome, nodular adrenal hyperplasia, and undetectable plasma corticotropin concentrations in whom food stimulated cortisol secretion. Cortisol secretion had an inverse diurnal rhythm in this patient, with low-to-normal fasting plasma cortisol concentrations and elevated postprandial cortisol concentrations that could not be suppressed with dexamethasone. The cortisol concentrations increased in response to oral glucose (4-fold increase) and a lipid-rich meal (4.8-fold increase) or a protein-rich meal (2.6-fold increase), but not intravenous glucose. The infusion of somatostatin blunted the plasma cortisol response to oral glucose. Intravenous infusion of gastric inhibitory polypeptide (GIP) for one hour increased the plasma cortisol concentration in the patient but not in four normal subjects. Fasting plasma GIP concentrations in the patient were similar to those in the normal subjects; feeding the patient test meals induced increases in plasma GIP concentrations that paralleled those in plasma cortisol concentrations. Cell suspensions of adrenal tissue from the patient produced more cortisol when stimulated by GIP than when stimulated by corticotropin. In contrast, adrenal cells from normal adults and fetuses or patients with cortisol-producting or aldosterone-producing adenomas responded to corticotropin but not to GIP. Nodular adrenal hyperplasia and Cushing's syndrome may be food-dependent as a result of abnormal responsiveness of adrenal cells to physiologic secretion of GIP. "Illicit" (ectopic) expression of GIP receptors on adrenal cells presumably underlies this disorder.

Consequences of copper treatment on pigeon pea photosynthesis, osmolytes and antioxidants defense.

PubMed

Sharma, Poonam; Sirhindi, Geetika; Singh, Anil Kumar; Kaur, Harpreet; Mushtaq, Ruqia

2017-10-01

An attempt was made to explore the effect of copper sulphate treatment on growth, photosynthesis, osmolytes and antioxidants in 15 days old seedlings of C. cajan (Pigeonpea). C. cajan seedlings were grown in 0, 1, 5 and 10 mM concentrations of copper sulphate in petriplates lined with Whatman filter paper for 15 days. Root length and shoot length was decreased in a dose dependent manner with highest decrease of 82.80 and 45.92% in 10 mM Cu stress. Photosynthetic efficiency (qP, qN and Y) was decreased in a dose dependent manner whereas NPQ was increased in 1 and 5 mM and decreased in 10 mM Cu. Photosynthetic pigments viz total chlorophyll and carotenoids were increased in low concentrations and decreased in high concentrations of Cu. Osmolytes such as proline, glycine betaine and sugars were found to be increased in a dose dependent manner. Similarly antioxidants such as superoxide dismutase and catalase increased to 129.17 and 169.7%, respectively under Cu stress. Vitamin C and vitamin E was also increased in different concentrations of Cu to a significant level. It can be concluded from the present study that C. cajan can tolerate Cu stress up to 5 mM by adjusting the proportion of proline, glycine betaine, sugars and vitamins along with increasing the activity of some of the antioxidant enzymes.

Enzymatic glucose sensor compensation for variations in ambient oxygen concentration

NASA Astrophysics Data System (ADS)

Collier, Bradley B.; McShane, Michael J.

2013-02-01

Due to the increasing prevalence of diabetes, research toward painless glucose sensing continues. Oxygen sensitive phosphors with glucose oxidase (GOx) can be used to determine glucose levels indirectly by monitoring oxygen consumption. This is an attractive combination because of its speed and specificity. Packaging these molecules together in "smart materials" for implantation will enable non-invasive glucose monitoring. As glucose levels increase, oxygen levels decrease; consequently, the luminescence intensity and lifetime of the phosphor increase. Although the response of the sensor is dependent on glucose concentration, the ambient oxygen concentration also plays a key role. This could lead to inaccurate glucose readings and increase the risk of hyper- or hypoglycemia. To mitigate this risk, the dependence of hydrogel glucose sensor response on oxygen levels was investigated and compensation methods explored. Sensors were calibrated at different oxygen concentrations using a single generic logistic equation, such that trends in oxygen-dependence were determined as varying parameters in the equation. Each parameter was found to be a function of oxygen concentration, such that the correct glucose calibration equation can be calculated if the oxygen level is known. Accuracy of compensation will be determined by developing an overall calibration, using both glucose and oxygen sensors in parallel, correcting for oxygen fluctuations in real time by intentionally varying oxygen, and calculating the error in actual and predicted glucose levels. While this method was developed for compensation of enzymatic glucose sensors, in principle it can also be implemented with other kinds of sensors utilizing oxidases.

Leiomyoma Cells in 3-Dimensional Cultures Demonstrate an Attenuated Response to Fasudil, a Rho-Kinase Inhibitor, When Compared to 2-Dimensional Cultures

PubMed Central

Malik, Minnie; Britten, Joy; Segars, James

2014-01-01

Uterine leiomyomata are common benign tumors in women of reproductive age and demonstrate an attenuated response to mechanical signaling that involves Rho and integrins. To further characterize the impairment in Rho signaling, we studied the effect of Rho-kinase inhibitor, fasudil, on extracellular matrix production, in 2-dimensional (2D) and 3-dimensional (3D) cultures of leiomyoma and myometrial cells. Leiomyoma 2D cultures demonstrated a rapid decrease in gene transcripts and protein for fibronectin, procollagen 1A, and versican. In 3D cultures, fibronectin and procollagen 1A proteins demonstrated increased levels at lower concentrations of fasudil, followed by a concentration-dependent decrease. Versican protein increased up to 3-fold, whereas fibromodulin demonstrated a significant decrease of 1.92-fold. Myometrial 2D or 3D cultures demonstrated a decrease in all proteins after 72 hours of treatment. The 3D leiomyoma cultures demonstrated a significant increase in active RhoA, followed by a concentration-dependent decrease at higher concentrations. A concentration-dependent increase in phospho-extracellular regulated signal kinase and proapoptotic protein Bax was observed in 3D leiomyoma cultures. Fasudil relaxed the contraction of the 3D collagen gels caused by myometrium and leiomyoma cell growth. These findings indicate that the altered state of Rho signaling in leiomyoma was more clearly observed in 3D cultures. The results also suggest that fasudil may have clinical applicability for treatment of uterine leiomyoma. PMID:25084783

TBT-induced imposex in marine neogastropods is mediated by an increasing androgen level

NASA Astrophysics Data System (ADS)

Bettin, C.; Oehlmann, J.; Stroben, E.

1996-09-01

Tributyltin (TBT) exposure at different concentrations (5, 60, and 100 ng TBT as Sn/l) induces a concentration- and time-dependent imposex (=pseudohermaphroditism) development in female Nucella lapillus and Hinia reticulata. In both species the average imposex stage, termed as vas deferens sequence (VDS) index, and the average female penis length increases with increasing TBT concentration and duration of TBT exposure. Testosterone added at a concentration of 500 ng/l induces a faster and more intensive imposex development compared to that induced by the TBT concentrations used in the present experiments. Radioimmunological determination of endogenous steroid content reveals increasing testosterone titres in female gastropods exposed to TBT which correlate with the TBT concentration used and the duration of the experiment. The most marked and highest increase of the endogenous testosterone level is exhibited by females, of both species exposed to testosterone. Simulataneous exposure to TBT and to the antiandrogen cyproterone acetate which suppresses imposex development completely in N. lapillus and reduces imposex development strongly in H. reticulata proves that the imposex-inducing effects of TBT are mediated by an increasing androgen level and are not caused directly by the organotin compound itself. Further-more, TBT-induced imposex development can be suppressed in both snails by adding estrogens to the aqueous medium. These observations suggest that TBT causes an inhibition of the cytochrome P-450 dependent aromatase system which catalyses the aromatization of androgens to estrogens. The increase of the androgen content or the shift of the androgen-estrogen balance in favour of androgens induces the development of pseudohermaphroditism in marine prosobranchs. Artificial inhibition of the cytochrome P-450 dependent aromatase system using SH 489 (1-methyl-1,4-androstadiene-3,17-dione) as a steroidal aromatase inhibitor and flavone as a nonsteroidal aromatase inhibitor induces imposex development in N. lapillus as well as in H. reticulata.

Concentration dependent switch in the kinetic pathway of lysozyme fibrillation: Spectroscopic and microscopic analysis

NASA Astrophysics Data System (ADS)

Kiran Kumar, E.; Prasad, Deepak Kumar; Prakash Prabhu, N.

2017-08-01

Formation of amyloid fibrils is found to be a general tendency of many proteins. Investigating the kinetic mechanisms and structural features of the intermediates and the final fibrillar state is essential to understand their role in amyloid diseases. Lysozyme, a notable model protein for amyloidogenic studies, readily formed fibrils in vitro at neutral pH in the presence of urea. It, however, showed two different kinetic pathways under varying urea concentrations when probed with thioflavin T (ThT) fluorescence. In 2 M urea, lysozyme followed a nucleation-dependent fibril formation pathway which was not altered by varying the protein concentration from 2 mg/ml to 8 mg/ml. In 4 M urea, the protein exhibited concentration dependent change in the mechanism. At lower protein concentrations, lysozyme formed fibrils without any detectable nuclei (nucleation-independent polymerization pathway). When the concentration of the protein was increased above 3 mg/ml, the protein followed nucleation-dependent polymerization pathway as observed in the case of 2 M urea condition. This was further verified using microscopic images of the fibrils. The kinetic parameters such as lag time, elongation rate, and fibrillation half-time, which were derived from ThT fluorescence changes, showed linear dependency against the initial protein concentration suggested that under the nucleation-dependent pathway conditions, the protein followed primary-nucleation mechanism without any significant secondary nucleation events. The results also suggested that the differences in the initial protein conformation might alter the mechanism of fibrillation; however, at the higher protein concentrations lysozyme shifted to nucleation-dependent pathway.

Repair strength dependence on solder protein concentration: a study in laser tissue-welding.

PubMed

Lauto, A

1998-01-01

A novel laser-activated solid solder has been coupled with a diode laser to investigate the dependence of the solder protein concentration on the tensile strength of the soldered tissues. The uncertainty of laser welding, due to the fluid glue, was overcome using the solid solder. Sixty-two severed rat tibial nerves and vas deferens were repaired using rectangular protein bands with two different albumin concentrations (58% and 68% by weight). The laser power (90 mW and 140 mW), dose (12.9 +/- 0.7 J/mg, mean +/- s.d.), and solder dimensions (thickness = 0.15 +/- 0.01 mm, surface area = 7.8 +/- 0.4 mm2) were kept constant during the operations. The laser welds with high protein solder concentration were significantly (P < 0.05) stronger (28 +/- 3.5 g) than the welds with low protein solder concentration (23 +/- 5 g). The average tensile strength of the laser soldered tissues increased as the protein solder concentration increased.

Mechanistic explanation of time-dependent cross-phenomenon based on quorum sensing: A case study of the mixture of sulfonamide and quorum sensing inhibitor to bioluminescence of Aliivibrio fischeri.

PubMed

Sun, Haoyu; Pan, Yongzheng; Gu, Yue; Lin, Zhifen

2018-07-15

Cross-phenomenon in which the concentration-response curve (CRC) for a mixture crosses the CRC for the reference model has been identified in many studies, expressed as a heterogeneous pattern of joint toxic action. However, a mechanistic explanation of the cross-phenomenon has thus far been extremely insufficient. In this study, a time-dependent cross-phenomenon was observed, in which the cross-concentration range between the CRC for the mixture of sulfamethoxypyridazine (SMP) and (Z-)-4-Bromo-5-(bromomethylene)-2(5H)-furanone (C30) to the bioluminescence of Aliivibrio fischeri (A. fischeri) and the CRC for independent action model with 95% confidence bands varied from low-concentration to higher-concentration regions in a timely manner expressed the joint toxic action of the mixture changing with an increase of both concentration and time. Through investigating the time-dependent hormetic effects of SMP and C30 (by measuring the expression of protein mRNA, simulating the bioluminescent reaction and analyzing the toxic action), the underlying mechanism was as follows: SMP and C30 acted on the quorum sensing (QS) system of A. fischeri, which induced low-concentration stimulatory effects and high-concentration inhibitory effects; in the low-concentration region, the stimulatory effects of SMP and C30 made the mixture produce a synergistic stimulation on the bioluminescence; thus, the joint toxic action exhibited antagonism. In the high-concentration region, the inhibitory effects of SMP and C30 in the mixture caused a double block in the loop circuit of the QS system; thus, the joint toxic action exhibited synergism. With the increase of time, these stimulatory and inhibitory effects of SMP and C30 were changed by the variation of the QS system at different growth phases, resulting in the time-dependent cross-phenomenon. This study proposes an induced mechanism for time-dependent cross-phenomenon based on QS, which may provide new insight into the mechanistic investigation of time-dependent cross-phenomenon, benefitting the environmental risk assessment of mixtures. Copyright © 2018 Elsevier B.V. All rights reserved.

Comparison of the effects of acute fluvoxamine and desipramine administration on melatonin and cortisol production in humans.

PubMed Central

Skene, D J; Bojkowski, C J; Arendt, J

1994-01-01

1. Acute administration of the specific serotonin uptake inhibitor, fluvoxamine (100 mg at 16.00 h), markedly increased nocturnal plasma melatonin concentrations, with high levels extending into the morning hours. 2. Acute administration of the noradrenaline uptake inhibitor, desipramine (DMI) (100 mg at 16.00 h), increased evening plasma melatonin concentrations. 3. Both drug treatments increased the duration of melatonin secretion, fluvoxamine significantly delaying the offset time and DMI significantly advancing the onset time. 4. The stimulatory effect of DMI on plasma melatonin was mirrored by increased urinary 6-sulphatoxymelatonin (aMT6s) excretion. 5. On the contrary, there was no correlation between plasma melatonin and urinary aMT6s concentrations following fluvoxamine treatment, suggesting that fluvoxamine may inhibit the metabolism of melatonin. 6. Treatment with DMI increased plasma cortisol concentrations in the evening and early morning, treatment with fluvoxamine increased plasma cortisol at 03.00 h, 10.00 h and 11.00 h. 7. The drug treatments affected different aspects of the nocturnal plasma melatonin profile suggesting that the amplitude of the melatonin rhythm may depend upon serotonin availability and/or melatonin metabolism whilst the onset of melatonin production depends upon noradrenaline availability. PMID:8186063

Segregation of chlorine in n-type tin monosulfide ceramics: Actual chlorine concentration for carrier-type conversion

NASA Astrophysics Data System (ADS)

Iguchi, Yuki; Sugiyama, Taiki; Inoue, Kazutoshi; Yanagi, Hiroshi

2018-05-01

Tin monosulfide (SnS) is an attractive material for photovoltaic cells because of its suitable band-gap energy, high absorption coefficient, and non-toxic and abundant constituent elements. The primary drawback of this material is the lack of n-type SnS. We recently demonstrated n-type SnS by doping with Cl. However, the Cl-doped n-type SnS bulk ceramics exhibited an odd behavior in which carrier-type conversion but not electron carrier concentration depended on the Cl concentration. In this study, the electron probe microanalysis (EPMA) elemental mapping of Cl-doped SnS revealed continuous homogeneous regions with a relatively low Cl concentration along with the islands of high Cl concentration in which Sn/S is far from unity. The difference between the Cl concentration in the homogeneous region (determined by EPMA) and the bulk Cl concentration (determined by wavelength-dispersive X-ray fluorescence spectroscopy) increased with the increasing Cl doping amount. The carrier concentration and the Hall coefficient clearly depended on the Cl concentration in the homogeneous region. Carrier-type conversion was observed at the Cl concentration of 0.26 at. % (in the homogeneous region).

Phosphate-dependent glutaminase in enterocyte mitochondria and its regulation by ammonium and other ions.

PubMed

Masola, B; Zvinavashe, E

2003-06-01

The effects of ammonium and other ions on phosphate dependent glutaminase (PDG) activity in intact rat enterocyte mitochondria were investigated. Sulphate and bicarbonate activated the enzyme in absence and presence of added phosphate. In presence of 10 mM phosphate, ammonium at concentrations <1 mM inhibited the enzyme. This inhibition was reversed by increased concentration of phosphate or sulphate. The inhibition of PDG by ammonium in presence of 10 mM phosphate was biphasic with respect to glutamine concentration, its effect being through a lowering of V(max) at glutamine concentration of

Pharmacologic characterization of the oxytocin receptor in human uterine smooth muscle cells

PubMed Central

Tahara, Atsuo; Tsukada, Junko; Tomura, Yuichi; Wada, Koh-ichi; Kusayama, Toshiyuki; Ishii, Noe; Yatsu, Takeyuki; Uchida, Wataru; Tanaka, Akihiro

2000-01-01

[3H]-oxytocin was used to characterize the oxytocin receptor found in human uterine smooth muscle cells (USMC). Specific binding of [3H]-oxytocin to USMC plasma membranes was dependent upon time, temperature and membrane protein concentration. Scatchard plot analysis of equilibrium binding data revealed the existence of a single class of high-affinity binding sites with an apparent equilibrium dissociation constant (Kd) of 0.76 nM and a maximum receptor density (Bmax) of 153 fmol mg−1 protein. The Hill coefficient (nH) did not differ significantly from unity, suggesting binding to homogenous, non-interacting receptor populations. Competitive inhibition of [3H]-oxytocin binding showed that oxytocin and vasopressin (AVP) receptor agonists and antagonists displaced [3H]-oxytocin in a concentration-dependent manner. The order of potencies for peptide agonists and antagonists was: oxytocin>[Asu1,6]-oxytocin>AVP= atosiban>d(CH2)5Tyr(Me)AVP>[Thr4,Gly7]-oxytocin>dDAVP, and for nonpeptide antagonists was: L-371257>YM087>SR 49059>OPC-21268>SR 121463A>OPC-31260. Oxytocin significantly induced concentration-dependent increase in intracellular Ca2+ concentration ([Ca2+]i) and hyperplasia in USMC. The oxytocin receptor antagonists, atosiban and L-371257, potently and concentration-dependently inhibited oxytocin-induced [Ca2+]i increase and hyperplasia. In contrast, the V1A receptor selective antagonist, SR 49059, and the V2 receptor selective antagonist, SR 121463A, did not potently inhibit oxytocin-induced [Ca2+]i increase and hyperplasia. The potency order of antagonists in inhibiting oxytocin-induced [Ca2+]i increase and hyperplasia was similar to that observed in radioligand binding assays. In conclusion, these data provide evidence that the high-affinity [3H]-oxytocin binding site found in human USMC is a functional oxytocin receptor coupled to [Ca2+]i increase and cell growth. Thus human USMC may prove to be a valuable tool in further investigation of the physiologic and pathophysiologic roles of oxytocin in the uterus. PMID:10694212

Leuco-crystal-violet micelle gel dosimeters: Component effects on dose-rate dependence

NASA Astrophysics Data System (ADS)

Xie, J. C.; Katz, E. A. B.; Alexander, K. M.; Schreiner, L. J.; McAuley, K. B.

2017-05-01

Designed experiments were performed to produce empirical models for the dose sensitivity, initial absorbance, and dose-rate dependence respectively for leucocrystal violet (LCV) micelle gel dosimeters containing cetyltrimethylammonium bromide (CTAB) and 2,2,2-trichloroethanol (TCE). Previous gels of this type showed dose-rate dependent behaviour, producing an ˜18% increase in dose sensitivity between dose rates of 100 and 600 cGy min-1. Our models predict that the dose rate dependence can be reduced by increasing the concentration of TCE, CTAB and LCV. Increasing concentrations of LCV and CTAB produces a significant increase in dose sensitivity with a corresponding increase in initial absorbance. An optimization procedure was used to determine a nearly dose-rate independent gel which maintained high sensitivity and low initial absorbance. This gel which contains 33 mM CTAB, 1.25 mM LCV, and 96 mM TCE in 25 mM trichloroacetic acid and 4 wt% gelatin showed an increase in dose sensitivity of only 4% between dose rates of 100 and 600 cGy min-1, and provides an 80% greater dose sensitivity compared to Jordan’s standard gels with similar initial absorbance.

Se enhanced phytoremediation of diesel in soil by Trifolium repens.

PubMed

Xi, Ying; Song, Yizhi; Johnson, David M; Li, Meng; Liu, Huigang; Huang, Yingping

2018-06-15

A pot-culture experiment was conducted to assess the effects of selenium (Se) (0.5 mg kg -1 ) on Trifolium repens exposed to various levels of diesel (0, 15, 20, 25 g kg -1 ) for 30 days and 60 days. Exposure to diesel for 60 day led to concentration-dependent decreases in root morphogenesis, chlorophyll content and CAT activity, and to dose-dependent increases in MDA content and SOD activity. The residual diesel concentration in soil increased and the removal efficiency decreased with soil diesel concentration. The chlorophyll content and residual diesel concentration after were slightly higher at 30 days than at 60days. Application of Se to soil increased Trifolium repens tolerance to diesel and significantly increased the phytoremediation effect at 60 days, with a removal rate of 36 ± 8%, compared to 28 ± 7% in the control. These results contribute to the ongoing effort to develop an effective phytoremediation system for soils highly contaminated by diesel. Copyright © 2018 Elsevier Inc. All rights reserved.

Regulation of Renal Urea Transport by Vasopressin

PubMed Central

Sands, Jeff M.; Blount, Mitsi A.; Klein, Janet D.

2011-01-01

Terrestrial life would be miserable without the ability to concentrate urine. Production of concentrated urine requires complex interactions among the nephron segments and vasculature in the kidney medulla. In addition to water channels (aquaporins) and sodium transporters, urea transporters are critically important to the theories proposed to explain the physiologic processes occurring when urine is concentrated. Vasopressin (anti-diuretic hormone) is the key hormone regulating the production of concentrated urine. Vasopressin rapidly increases water and urea transport in the terminal inner medullary collecting duct (IMCD). Vasopressin rapidly increases urea permeability in the IMCD through increases in phosphorylation and apical plasma-membrane accumulation of the urea transporter A1 (UT-A1). Vasopressin acts through two cAMP-dependent signaling pathways in the IMCD: protein kinase A and exchange protein activated by cAMP Epac. Protein kinase A phosphorylates UT-A1 at serines 486 and 499. In summary, vasopressin regulates urea transport acutely by increasing UT-A1 phosphorylation and the apical plasma-membrane accumulation of UT-A1 through two cAMP-dependent pathways. PMID:21686211

Insulin-like growth factor-1 protects preimplantation embryos from anti-developmental actions of menadione.

PubMed

Moss, James I; Pontes, Eduardo; Hansen, Peter James

2009-11-01

Menadione is a naphthoquinone used as a vitamin K source in animal feed that can generate reactive oxygen species (ROS) and cause apoptosis. Here, we examined whether menadione reduces development of preimplantation bovine embryos in a ROS-dependent process and tested the hypothesis that actions of menadione would be reduced by insulin-like growth factor-1 (IGF-1). Menadione caused a concentration-dependent decrease in the proportion of embryos that became blastocysts. All concentrations tested (1, 2.5, and 5.0 microM) inhibited development. Treatment with 100 ng/ml IGF-1 reduced the magnitude of the anti-developmental effects of the two lowest menadione concentrations. Menadione also caused a concentration-dependent increase in the percent of cells positive for the TUNEL reaction. The response was lower for IGF-1-treated embryos. The effects of menadione were mediated by ROS because (1) the anti-developmental effect of menadione was blocked by the antioxidants dithiothreitol and Trolox and (2) menadione caused an increase in ROS generation. Treatment with IGF-1 did not reduce ROS formation in menadione-treated embryos. In conclusion, concentrations of menadione as low as 1.0 muM can compromise development of bovine preimplantation embryos to the blastocyst stage of development in a ROS-dependent mechanism. Anti-developmental actions of menadione can be blocked by IGF-1 through effects downstream of ROS generation.

Icosapent ethyl: Eicosapentaenoic acid concentration and triglyceride-lowering effects across clinical studies.

PubMed

Bays, Harold E; Ballantyne, Christie M; Doyle, Ralph T; Juliano, Rebecca A; Philip, Sephy

2016-09-01

Icosapent ethyl is a high-purity prescription form of eicosapentaenoic acid (EPA) ethyl ester approved at a dose of 4g/day as an adjunct to diet to reduce triglyceride (TG) levels in adult patients with severe (≥500mg/dL) hypertriglyceridemia. This post-hoc exploratory analysis examined the relationship of icosapent ethyl dose with EPA concentrations in plasma and red blood cells (RBCs) across 3 clinical studies-a phase 1 pharmacokinetic study in healthy adult volunteers and 2 pivotal phase 3 studies (MARINE and ANCHOR) in adult patients with hypertriglyceridemia-and examined the relationship between EPA levels and TG-lowering effects in MARINE and ANCHOR. In all 3 studies, icosapent ethyl produced dose-dependent increases in the concentrations of EPA in plasma and RBCs. In both MARINE and ANCHOR, these dose-dependent EPA increases correlated with the degree of TG level lowering (all P<0.01). In patients with high TG levels (≥200mg/dL) and treated with icosapent ethyl 4g/day, the end-of-treatment plasma and RBC EPA concentrations were >170μg/mL and>70μg/mL, respectively. These studies support icosapent ethyl as producing predictable dose-dependent pharmacokinetics/pharmacodynamics, with TG level lowering dependent upon icosapent ethyl dose and EPA concentrations in plasma and RBCs. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Effects of the addition of different nitrogen sources in the tequila fermentation process at high sugar concentration.

PubMed

Arrizon, J; Gschaedler, A

2007-04-01

To study the effect of the addition of different nitrogen sources at high sugar concentration in the tequila fermentation process. Fermentations were performed at high sugar concentration (170 g l(-1)) using Agave tequilana Weber blue variety with and without added nitrogen from different sources (ammonium sulfate; glutamic acid; a mixture of ammonium sulfate and amino acids) during the exponential phase of growth. All the additions increased the fermentation rate and alcohol efficiency. The level of synthesis of volatile compounds depended on the source added. The concentration of amyl alcohols and isobutanol were decreased while propanol and acetaldehyde concentration increased. The most efficient nitrogen sources for fermentation rate were ammonium sulfate and the mixture of ammonium sulfate and amino acids. The level of volatile compounds produced depended upon types of nitrogen. The synthesis of some volatile compounds increased while others decreased with nitrogen addition. The addition of nitrogen could be a strategy for improving the fermentation rate and efficiency in the tequila fermentation process at high sugar Agave tequilana concentration. Furthermore, the sensory quality of the final product may change because the synthesis of the volatile compounds is modified.

Electrospinning of nickel oxide nanofibers: Process parameters and morphology control

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

Khalil, Abdullah, E-mail: akhalil@masdar.ac.ae; Hashaikeh, Raed, E-mail: rhashaikeh@masdar.ac.ae

2014-09-15

In the present work, nickel oxide nanofibers with varying morphology (diameter and roughness) were fabricated via electrospinning technique using a precursor composed of nickel acetate and polyvinyl alcohol. It was found that the diameter and surface roughness of individual nickel oxide nanofibers are strongly dependent upon nickel acetate concentration in the precursor. With increasing nickel acetate concentration, the diameter of nanofibers increased and the roughness decreased. An optimum concentration of nickel acetate in the precursor resulted in the formation of smooth and continuous nickel oxide nanofibers whose diameter can be further controlled via electrospinning voltage. Beyond an optimum concentration ofmore » nickel acetate, the resulting nanofibers were found to be ‘flattened’ and ‘wavy’ with occasional cracking across their length. Transmission electron microscopy analysis revealed that the obtained nanofibers are polycrystalline in nature. These nickel oxide nanofibers with varying morphology have potential applications in various engineering domains. - Highlights: • Nickel oxide nanofibers were synthesized via electrospinning. • Fiber diameter and roughness depend on nickel acetate concentration used. • With increasing nickel acetate concentration the roughness of nanofibers decreased. • XRD and TEM revealed a polycrystalline structure of the nanofibers.« less

Effects of Sublethal Concentrations of the Chitin Synthesis Inhibitor, Hexaflumuron, on the Development and Hemolymph Physiology of the Cutworm, Spodoptera litura

PubMed Central

Zhu, Qiqi; He, Yuan; Yao, Jing; Liu, Yinzhao; Tao, Liming; Huang, Qingchun

2012-01-01

The effects of sublethal concentrations 0.1, 0.5, and 1.2 µg mL-1of the chitin synthesis inhibitor, hexaflumuron, on larval growth and development, the count and proportion of hemocytes, and carbohydrate content (trehalose and glyceride) in hemolymph were investigated in the cutworm, Spodoptera litura (Fabricious) (Lepidoptera: Noctuidae). When 3rdinstar larvae were subjected to the sublethal concentrations, there were dose-dependent effects on larval weight and length of each instar larvae, percent pupation and the duration of development. Most of the larvae died during the molting process at all concentrations. Few individuals from 0.5 and 1.2 µg mL -1concentrations could develop to the 6thinstar, while the pupae emerging from the 0.1 µg mL -1concentrations did not exceed 16% of the number of the initial larvae. In 5thinstar S. litura, the total number of hemocytes was significantly increased at 24 hours post—treatment, whereas the proliferation of hemocytes was inhibited, plasmatocyte pseudopodia contracted, and granulocyte expanded at 96 hours post—treatment. The increases of plasmatocyte count and the decreases of granulocyte count were dose—dependent. The longer treatment time of the sublethal concentrations increased the content of total carbohydrate and trehalose in hematoplasma, and was dose—dependent in hemocytes. The content of glyceride in hemolymph was significantly higher at 24 hours post—treatment, but gradually returned to normal levels at 96 hours post—treatment as compared with the control. The results suggested that sublethal concentrations of hexaflumuron reduced S. litura larval survival and interfered with hemolymph physiological balances. PMID:22958164

Gestational age and dose influence on placental transfer of 63Ni in rats.

PubMed

Wang, X-W; Gu, J-Y; Li, Z; Song, Y-F; Wu, W-S; Hou, Y-P

2010-04-01

The effects of gestational age and dose of nickel exposure on regulating and influencing placental transfer were investigated. Pregnant rats on gestational day (GD) 12, 15 or 20 were injected intraperitoneally with saline, 64,320 or 640 kBq/kg body weight of (63)Ni. Twenty-four hours after administration, samples were harvested from each for measurement of radioactivity by liquid scintillation counting and for autoradiography. In placenta, amniotic fluid and fetal membrane, (63)Ni concentrations increased with increasing doses and gestational age. In fetus, (63)Ni concentrations reached a maximum on GD 15 and then declined on GD 20 although they maintained a dose-dependency for each GD group. In fetal blood on GD 20, (63)Ni concentration increased dose-dependently and was higher than in maternal blood. The autoradiographs demonstrated that (63)Ni radioactivity was located within placental basal lamina, fetal bones and most organs. These findings suggest that the nickel uptake, retention and transport in placenta increase dose- and gestation age-dependently, and nickel transfer through placental barrier is primarily from mother into the fetus, but hardly from fetus to mother. Copyright 2010 Elsevier Ltd. All rights reserved.

Chronic Exposure to Zinc Chromate Induces Centrosome Amplification and Spindle Assembly Checkpoint Bypass in Human Lung Fibroblasts

PubMed Central

Holmes, Amie L.; Wise, Sandra S.; Pelsue, Stephen C.; Aboueissa, AbouEl-Makarim; Lingle, Wilma; Salisbury, Jeffery; Gallagher, Jamie; Wise, John Pierce

2010-01-01

Hexavalent chromium (Cr(VI)) compounds are known human lung carcinogens. Solubility plays an important role in its carcinogenicity with the particulate or insoluble form being the most potent. Of the particulate Cr(VI) compounds, zinc chromate appears to be the most potent carcinogen, however, very few studies have investigated its carcinogenic mechanism. In this study, we investigated the ability of chronic exposure to zinc chromate to induce numerical chromosome instability. We found no increase in aneuploidy after a 24 hour exposure to zinc chromate, but with more chronic exposures, zinc chromate induced concentration- and time-dependent increases in aneuploidy in the form of hypodiploidy, hyperdiploidy and tetraploidy. Zinc chromate also induced centrosome amplification in a concentration- and time-dependent manner in both interphase and mitotic cells after chronic exposure, producing cells with centriolar defects. Further, chronic exposure to zinc chromate induced concentration- and time-dependent increases in spindle assembly checkpoint bypass with increases in centromere spreading, premature centromere division and premature anaphase. Lastly, we found that chronic exposure to zinc chromate induced a G2 arrest. All together, these data indicate that zinc chromate can induce chromosome instability after prolonged exposures. PMID:20030412

Nonlinear photoacoustic spectroscopy of hemoglobin

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

Danielli, Amos; Maslov, Konstantin; Favazza, Christopher P.

2015-05-18

As light intensity increases in photoacoustic imaging, the saturation of optical absorption and the temperature dependence of the thermal expansion coefficient result in a measurable nonlinear dependence of the photoacoustic (PA) signal on the excitation pulse fluence. Here, under controlled conditions, we investigate the intensity-dependent photoacoustic signals from oxygenated and deoxygenated hemoglobin at varied optical wavelengths and molecular concentrations. The wavelength and concentration dependencies of the nonlinear PA spectrum are found to be significantly greater in oxygenated hemoglobin than in deoxygenated hemoglobin. These effects are further influenced by the hemoglobin concentration. These nonlinear phenomena provide insights into applications of photoacoustics,more » such as measurements of average inter-molecular distances on a nm scale or with a tuned selection of wavelengths, a more accurate quantitative PA tomography.« less

[Effect of chloride ion on corrosion of two commonly used dental alloys].

PubMed

Chen, Lei; Zhang, Weidan; Zhang, Yuanyuan

2014-11-01

To investigate the eff ect of chloride concentration on the corrosion of Co-Cr alloy and pure Ti in a simulated oral environment. The electrochemical corrosion tests of pure Ti and Co-Cr alloy were carried out in neutral artificial saliva solutions with different NaCl concentrations (0.9%, 2.0%, and 3.0%). Th e morphologies of corroded surface for pure Ti and Co-Cr alloy were observed by scanning electron microscope (SEM). Th e changes in the self-corrosion potentials (Ecorr) for pure Ti and Co-Cr alloy in three kinds of artificial saliva solutions was not obvious. However, the self-corrosion current densities (Icorr) of pure Ti were much lower than those of Co-Cr. The Icorr of Co-Cr alloy increased in a concentration-dependent manner of NaCl, whereas the breakdown potential (Eb) of Co-Cr alloy decreased in a concentration-dependent manner. Th e potential ranged for the breakdown of oxide film (Ev) was shortened in a concentration-dependent manner of NaCl. There was no obvious difference in the Icorr of pure Ti with different concentrations of NaCl. The breakdown potential was not seen according to the polarization curves. In a certain range, the increase of the concentration of Cl- leads to accelerate the corrosion behavior of Co-Cr alloy, but it does not affect pure Ti.

Optimal concentrations in nectar feeding

PubMed Central

Kim, Wonjung; Gilet, Tristan; Bush, John W. M.

2011-01-01

Nectar drinkers must feed quickly and efficiently due to the threat of predation. While the sweetest nectar offers the greatest energetic rewards, the sharp increase of viscosity with sugar concentration makes it the most difficult to transport. We here demonstrate that the sugar concentration that optimizes energy transport depends exclusively on the drinking technique employed. We identify three nectar drinking techniques: active suction, capillary suction, and viscous dipping. For each, we deduce the dependence of the volume intake rate on the nectar viscosity and thus infer an optimal sugar concentration consistent with laboratory measurements. Our results provide the first rationale for why suction feeders typically pollinate flowers with lower sugar concentration nectar than their counterparts that use viscous dipping. PMID:21949358

A reactive oxygen species activation mechanism contributes to JS-K-induced apoptosis in human bladder cancer cells.

PubMed

Qiu, Mingning; Chen, Lieqian; Tan, Guobin; Ke, Longzhi; Zhang, Sai; Chen, Hege; Liu, Jianjun

2015-10-13

Reactive oxygen species (ROS) and cellular oxidant stress are regulators of cancer cells. The alteration of redox status, which is induced by increased generation of ROS, results in increased vulnerability to oxidative stress. The aim of this study is to investigate the influence of O2-(2,4-dinitrophenyl) 1-[(4-ethoxycarbonyl)piperazin-1-yl]diazen-1-ium-1,2-diolate (JS-K, C13H16N6O8) on proliferation and apoptosis in bladder cancer cells and explored possible ROS-related mechanisms. Our results indicated that JS-K could suppress bladder cancer cell proliferation in a concentration- and time-dependent manner and induce apoptosis and ROS accumulation in a concentration-dependent manner. With increasing concentrations of JS-K, expression of proteins that are involved in cell apoptosis increased in a concentration-dependent manner. Additionally, the antioxidant N-acetylcysteine (NAC) reversed JS-K-induced cell apoptosis; conversely, the prooxidant oxidized glutathione (GSSG) exacerbated JS-K-induced cell apoptosis. Furthermore, we found that nitrites, which were generated from the oxidation of JS-K-released NO, induced apoptosis in bladder cancer cells to a lower extent through the ROS-related pathway. In addition, JS-K was shown to enhance the chemo-sensitivity of doxorubicin in bladder cancer cells. Taken together, the data suggest that JS-K-released NO induces bladder cancer cell apoptosis by increasing ROS levels, and nitrites resulting from oxidation of NO have a continuous apoptosis-inducing effect.

A reactive oxygen species activation mechanism contributes to JS-K-induced apoptosis in human bladder cancer cells

PubMed Central

Qiu, Mingning; Chen, Lieqian; Tan, Guobin; Ke, Longzhi; Zhang, Sai; Chen, Hege; Liu, Jianjun

2015-01-01

Reactive oxygen species (ROS) and cellular oxidant stress are regulators of cancer cells. The alteration of redox status, which is induced by increased generation of ROS, results in increased vulnerability to oxidative stress. The aim of this study is to investigate the influence of O2-(2,4-dinitrophenyl) 1-[(4-ethoxycarbonyl)piperazin-1-yl]diazen-1-ium-1,2-diolate (JS-K, C13H16N6O8) on proliferation and apoptosis in bladder cancer cells and explored possible ROS-related mechanisms. Our results indicated that JS-K could suppress bladder cancer cell proliferation in a concentration- and time-dependent manner and induce apoptosis and ROS accumulation in a concentration-dependent manner. With increasing concentrations of JS-K, expression of proteins that are involved in cell apoptosis increased in a concentration-dependent manner. Additionally, the antioxidant N-acetylcysteine (NAC) reversed JS-K-induced cell apoptosis; conversely, the prooxidant oxidized glutathione (GSSG) exacerbated JS-K-induced cell apoptosis. Furthermore, we found that nitrites, which were generated from the oxidation of JS-K-released NO, induced apoptosis in bladder cancer cells to a lower extent through the ROS-related pathway. In addition, JS-K was shown to enhance the chemo-sensitivity of doxorubicin in bladder cancer cells. Taken together, the data suggest that JS-K-released NO induces bladder cancer cell apoptosis by increasing ROS levels, and nitrites resulting from oxidation of NO have a continuous apoptosis-inducing effect. PMID:26458509

Small-Angle Neutron Scattering and Neutron Spin Echo Characterization of Monoclonal Antibody Self-Associations at High Concentrations

NASA Astrophysics Data System (ADS)

Yearley, Eric; Zarraga, Isidro (Dan); Godfrin, Paul (Doug); Perevozchikova, Tatiana; Wagner, Norman; Liu, Yun

2013-03-01

Concentrated therapeutic protein formulations offer numerous delivery and stability challenges. In particular, it has been found that several therapeutic proteins exhibit a large increase in viscosity as a function of concentration that may be dependent on the protein-protein interactions. Small-Angle Neutron Scattering (SANS) and Neutron Spin Echo (NSE) investigations have been performed to probe the protein-protein interactions and diffusive properties of highly concentrated MAbs. The SANS data demonstrate that the inter-particle interactions for a highly viscous MAb at high concentrations (MAb1) are highly attractive, anisotropic and change significantly with concentration while the viscosity and interactions do not differ considerably for MAb2. The NSE results furthermore indicate that MAb1 and MAb2 have strong concentration dependencies of dynamics at high Q that are correlated to the translational motion of the proteins. Finally, it has also been revealed that the individual MAb1 proteins form small clusters at high concentrations in contrast to the MAb2 proteins, which are well-dispersed. It is proposed that the formation of these clusters is the primary cause of the dramatic increase in viscosity of MAb1 in crowded or concentrated environments.

On the Alloying and Properties of Tetragonal Nb₅Si₃ in Nb-Silicide Based Alloys.

PubMed

Tsakiropoulos, Panos

2018-01-04

The alloying of Nb₅Si₃ modifies its properties. Actual compositions of (Nb,TM)₅X₃ silicides in developmental alloys, where X = Al + B + Ge + Si + Sn and TM is a transition and/or refractory metal, were used to calculate the composition weighted differences in electronegativity (Δχ) and an average valence electron concentration (VEC) and the solubility range of X to study the alloying and properties of the silicide. The calculations gave 4.11 < VEC < 4.45, 0.103 < Δχ < 0.415 and 33.6 < X < 41.6 at.%. In the silicide in Nb-24Ti-18Si-5Al-5Cr alloys with single addition of 5 at.% B, Ge, Hf, Mo, Sn and Ta, the solubility range of X decreased compared with the unalloyed Nb₅Si₃ or exceeded 40.5 at.% when B was with Hf or Mo or Sn and the Δχ decreased with increasing X. The Ge concentration increased with increasing Ti and the Hf concentration increased and decreased with increasing Ti or Nb respectively. The B and Sn concentrations respectively decreased and increased with increasing Ti and also depended on other additions in the silicide. The concentration of Sn was related to VEC and the concentrations of B and Ge were related to Δχ. The alloying of Nb₅Si₃ was demonstrated in Δχ versus VEC maps. Effects of alloying on the coefficient of thermal expansion (CTE) anisotropy, Young's modulus, hardness and creep data were discussed. Compared with the hardness of binary Nb₅Si₃ (1360 HV), the hardness increased in silicides with Ge and dropped below 1360 HV when Al, B and Sn were present without Ge. The Al effect on hardness depended on other elements substituting Si. Sn reduced the hardness. Ti or Hf reduced the hardness more than Cr in Nb₅Si₃ without Ge. The (Nb,Hf)₅(Si,Al)₃ had the lowest hardness. VEC differentiated the effects of additions on the hardness of Nb₅Si₃ alloyed with Ge. Deterioration of the creep of alloyed Nb₅Si₃ was accompanied by decrease of VEC and increase or decrease of Δχ depending on alloying addition(s).

Ultrafine particle concentrations in and around idling school buses

NASA Astrophysics Data System (ADS)

Zhang, Qunfang; Fischer, Heidi J.; Weiss, Robert E.; Zhu, Yifang

2013-04-01

Unnecessary school bus idling increases children's exposure to diesel exhaust, but to what extent children are exposed to ultrafine particles (UFPs, diameter < 100 nm) in and around idling school buses remains unclear. This study employed nine school buses and simulated five scenarios by varying emissions source, wind direction, and window position. The purpose was to investigate the impact of idling on UFP number concentration and PM2.5 mass concentration inside and near school buses. Near the school buses, total particle number concentration increased sharply from engine off to engine on under all scenarios, by a factor of up to 26. The impact of idling on UFP number concentration inside the school buses depended on wind direction and window position: wind direction was important and statistically significant while the effect of window positions depended on wind direction. Under certain scenarios, idling increased in-cabin total particle number concentrations by a factor of up to 5.8, with the significant increase occurring in the size range of 10-30 nm. No significant change of in-cabin PM2.5 mass concentration was observed due to idling, regardless of wind direction and window position, indicating that PM2.5 is not a good indicator for primary diesel exhaust particle exposure. The deposition rates based on total particle number concentration inside school bus cabins varied between 1.5 and 5.0 h-1 across nine tested buses under natural convection conditions, lower than those of passenger cars but higher than those of indoor environments.

The ignition delay times of hydrogen/silan/air mixtures at low temperatures

NASA Astrophysics Data System (ADS)

Tropin, D. A.; Bochenkov, E. S.; Fedorov, A. V.

2018-03-01

In the paper the ignition delay times of hydrogen-silane-air mixtures at low pressures from 0.4 atm to 1 atm and mixture temperatures from 300 K to 900 K using the detailed kinetic mechanisms were calculated. It was shown that dependencies of ignition delay time on temperature are non-monotonic. In these dependences a region of "negative temperature coefficient" is presented. The effect of the mixture pressure and the silane concentration in the mixture on the length of this region was revealed. It was shown that the increasing of the silane concentration in the mixture, as well as the increasing the mixture pressure, leads to increasing of the "negative temperature coefficient" region length.

Carrier concentration dependent photoluminescence properties of Si-doped InAs nanowires

NASA Astrophysics Data System (ADS)

Sonner, M.; Treu, J.; Saller, K.; Riedl, H.; Finley, J. J.; Koblmüller, G.

2018-02-01

We report the effects of intentional n-type doping on the photoluminescence (PL) properties of InAs nanowires (NWs). Employing silicon (Si) as a dopant in molecular beam epitaxy grown NWs, the n-type carrier concentration is tuned between 1 × 1017 cm-3 and 3 × 1018 cm-3 as evaluated from Fermi-tail fits of the high-energy spectral region. With the increasing carrier concentration, the PL spectra exhibit a distinct blueshift (up to ˜50 meV), ˜2-3-fold peak broadening, and a redshift of the low-energy tail, indicating both the Burstein-Moss shift and bandgap narrowing. The low-temperature bandgap energy (EG) decreases from ˜0.44 eV (n ˜ 1017 cm-3) to ˜0.41 eV (n ˜ 1018 cm-3), following a ΔEG ˜ n1/3 dependence. Simultaneously, the PL emission is quenched nearly 10-fold, while the pump-power dependent analysis of the integrated PL intensity evidences a typical 2/3-power-law scaling, indicative of non-radiative Auger recombination at high carrier concentrations. Carrier localization and activation at stacking defects are further observed in undoped InAs NWs by temperature-dependent measurements but are absent in Si-doped InAs NWs due to the increased Fermi energy.

Magnetic storms and variations in hormone levels among residents of North Polar area - Svalbard

NASA Astrophysics Data System (ADS)

Breus, T. K.; Boiko, E. R.; Zenchenko, T. A.

2015-01-01

In the present work four examinations (January, March, June, October 1991-1992) of the blood concentration of adrenal hormones (cortisol) and thyroid hormones (triiodothyronine (T3) and thyroxine T4) and their dependence on space and terrestrial weather parameters have been done for large groups of healthy inhabitants of high latitudes (Svalbard, the most northerly in the world year-round inhabited settlements). The aim of this study was to find the possible sensitivity of these biochemical parameters to variations of external natural factors at high latitudes in three independent groups of people living in this region (miners and people working underground (364 samples), the men working on the ground (274 samples) and women working on the ground (280 samples)). The obtained data indicate that the most expressed dependence of concentration of the three studied hormones is on the level of geomagnetic activity (GMA) - Kp, Ap, Kpmax - 3h. For two of the four seasons (June and October) with increasing levels of GMA a significant (p < 0.05) increase in cortisol concentration in all three independent groups of people was observed. Range of increases in cortisol concentration in different groups were about 30% of the observed variation in the average intragroup concentration in June and from 16% to 38% in October. For T3 dependence was found only in June: drop in hormone secretion with increasing levels of GMA from 18 to 30% of the average range of intragroup variations. Thus it was shown for the first time that at high geographical latitudes with increased level of GMA a significant change in the level of secretion of several hormones leads to the type of adaptive stress reaction.

Magnetic storms and variations in hormone levels among residents of North Polar area--Svalbard.

PubMed

Breus, T K; Boiko, E R; Zenchenko, T A

2015-01-01

In the present work four examinations (January, March, June, October 1991-1992) of the blood concentration of adrenal hormones (cortisol) and thyroid hormones (triiodothyronine (T3) and thyroxine T4) and their dependence on space and terrestrial weather parameters have been done for large groups of healthy inhabitants of high latitudes (Svalbard, the most northerly in the world year-round inhabited settlements). The aim of this study was to find the possible sensitivity of these biochemical parameters to variations of external natural factors at high latitudes in three independent groups of people living in this region (miners and people working underground (364 samples), the men working on the ground (274 samples) and women working on the ground (280 samples)). The obtained data indicate that the most expressed dependence of concentration of the three studied hormones is on the level of geomagnetic activity (GMA) - Kp, Ap, Kpmax - 3h. For two of the four seasons (June and October) with increasing levels of GMA a significant (p<0.05) increase in cortisol concentration in all three independent groups of people was observed. Range of increases in cortisol concentration in different groups were about 30% of the observed variation in the average intragroup concentration in June and from 16% to 38% in October. For T3 dependence was found only in June: drop in hormone secretion with increasing levels of GMA from 18 to 30% of the average range of intragroup variations. Thus it was shown for the first time that at high geographical latitudes with increased level of GMA a significant change in the level of secretion of several hormones leads to the type of adaptive stress reaction. Copyright © 2014 The Committee on Space Research (COSPAR). Published by Elsevier Ltd. All rights reserved.

Temperature Dependence of Inorganic Nitrogen Uptake: Reduced Affinity for Nitrate at Suboptimal Temperatures in Both Algae and Bacteria

PubMed Central

Reay, David S.; Nedwell, David B.; Priddle, Julian; Ellis-Evans, J. Cynan

1999-01-01

Nitrate utilization and ammonium utilization were studied by using three algal isolates, six bacterial isolates, and a range of temperatures in chemostat and batch cultures. We quantified affinities for both substrates by determining specific affinities (specific affinity = maximum growth rate/half-saturation constant) based on estimates of kinetic parameters obtained from chemostat experiments. At suboptimal temperatures, the residual concentrations of nitrate in batch cultures and the steady-state concentrations of nitrate in chemostat cultures both increased. The specific affinity for nitrate was strongly dependent on temperature (Q10 ≈ 3, where Q10 is the proportional change with a 10°C temperature increase) and consistently decreased at temperatures below the optimum temperature. In contrast, the steady-state concentrations of ammonium remained relatively constant over the same temperature range, and the specific affinity for ammonium exhibited no clear temperature dependence. This is the first time that a consistent effect of low temperature on affinity for nitrate has been identified for psychrophilic, mesophilic, and thermophilic bacteria and algae. The different responses of nitrate uptake and ammonium uptake to temperature imply that there is increasing dependence on ammonium as an inorganic nitrogen source at low temperatures. PMID:10347046

In-silico prediction of concentration-dependent viscosity curves for monoclonal antibody solutions

PubMed Central

Tomar, Dheeraj S.; Li, Li; Broulidakis, Matthew P.; Luksha, Nicholas G.; Burns, Christopher T.; Singh, Satish K.; Kumar, Sandeep

2017-01-01

ABSTRACT Early stage developability assessments of monoclonal antibody (mAb) candidates can help reduce risks and costs associated with their product development. Forecasting viscosity of highly concentrated mAb solutions is an important aspect of such developability assessments. Reliable predictions of concentration-dependent viscosity behaviors for mAb solutions in platform formulations can help screen or optimize drug candidates for flexible manufacturing and drug delivery options. Here, we present a computational method to predict concentration-dependent viscosity curves for mAbs solely from their sequence—structural attributes. This method was developed using experimental data on 16 different mAbs whose concentration-dependent viscosity curves were experimentally obtained under standardized conditions. Each concentration-dependent viscosity curve was fitted with a straight line, via logarithmic manipulations, and the values for intercept and slope were obtained. Intercept, which relates to antibody diffusivity, was found to be nearly constant. In contrast, slope, the rate of increase in solution viscosity with solute concentration, varied significantly across different mAbs, demonstrating the importance of intermolecular interactions toward viscosity. Next, several molecular descriptors for electrostatic and hydrophobic properties of the 16 mAbs derived using their full-length homology models were examined for potential correlations with the slope. An equation consisting of hydrophobic surface area of full-length antibody and charges on VH, VL, and hinge regions was found to be capable of predicting the concentration-dependent viscosity curves of the antibody solutions. Availability of this computational tool may facilitate material-free high-throughput screening of antibody candidates during early stages of drug discovery and development. PMID:28125318

In-silico prediction of concentration-dependent viscosity curves for monoclonal antibody solutions.

PubMed

Tomar, Dheeraj S; Li, Li; Broulidakis, Matthew P; Luksha, Nicholas G; Burns, Christopher T; Singh, Satish K; Kumar, Sandeep

2017-04-01

Early stage developability assessments of monoclonal antibody (mAb) candidates can help reduce risks and costs associated with their product development. Forecasting viscosity of highly concentrated mAb solutions is an important aspect of such developability assessments. Reliable predictions of concentration-dependent viscosity behaviors for mAb solutions in platform formulations can help screen or optimize drug candidates for flexible manufacturing and drug delivery options. Here, we present a computational method to predict concentration-dependent viscosity curves for mAbs solely from their sequence-structural attributes. This method was developed using experimental data on 16 different mAbs whose concentration-dependent viscosity curves were experimentally obtained under standardized conditions. Each concentration-dependent viscosity curve was fitted with a straight line, via logarithmic manipulations, and the values for intercept and slope were obtained. Intercept, which relates to antibody diffusivity, was found to be nearly constant. In contrast, slope, the rate of increase in solution viscosity with solute concentration, varied significantly across different mAbs, demonstrating the importance of intermolecular interactions toward viscosity. Next, several molecular descriptors for electrostatic and hydrophobic properties of the 16 mAbs derived using their full-length homology models were examined for potential correlations with the slope. An equation consisting of hydrophobic surface area of full-length antibody and charges on V H , V L , and hinge regions was found to be capable of predicting the concentration-dependent viscosity curves of the antibody solutions. Availability of this computational tool may facilitate material-free high-throughput screening of antibody candidates during early stages of drug discovery and development.

Spectroscopic Study of Deep Level Emissions from Acceptor Defects in ZnO Thin Films with Oxygen Rich Stoichiometry

NASA Astrophysics Data System (ADS)

Ilyas, Usman; Rawat, R. S.; Tan, T. L.

2013-10-01

This paper reports the tailoring of acceptor defects in oxygen rich ZnO thin films at different post-deposition annealing temperatures (500-800°C) and Mn doping concentrations. The XRD spectra exhibited the nanocrystalline nature of ZnO thin films along with inconsistent variation in lattice parameters suggesting the temperature-dependent activation of structural defects. Photoluminescence emission spectra revealed the temperature dependent variation in deep level emissions (DLE) with the presence of acceptors as dominating defects. The concentration of native defects was estimated to be increased with temperature while a reverse trend was observed for those with increasing doping concentration. A consistent decrease in DLE spectra, with increasing Mn content, revealed the quenching of structural defects in the optical band gap of ZnO favorable for good quality thin films with enhanced optical transparency.

Thalidomide has a significant effect in patients with thalassemia intermedia.

PubMed

Li, YunShuan; Ren, Quan; Zhou, Yali; Li, Pingping; Lin, Wanhua; Yin, Xiaolin

2018-01-01

To investigate the effect of thalidomide in patients with thalassemia intermedia. We observed the effect of thalidomide in seven patients with thalassemia intermedia requiring blood transfusion. Four of the patients were transfusion-independent, and three patients were transfusion-dependent. For the four transfusion-independent patients, hemoglobin concentration increased significantly (≥2 g/dl) in three and moderately (1-2 g/dl) in one. After 3 months of treatment, hemoglobin concentration increased 3.2 ± 1.2 g/dl compared to pretreatment. Among the three transfusion-dependent patients, transfusion was terminated after one month of treatment in one patient and decreased >50% in the other two patients, accompanied by an increase in the average hemoglobin concentration. Thalidomide had a significant effect in patients with thalassemia intermedia. Further studies of a larger scale and more rigorous design are warranted.

Equilibrium and kinetic modelling of chromium(III) sorption by animal bones.

PubMed

Chojnacka, Katarzyna

2005-04-01

The paper discusses sorption of Cr(III) ions from aqueous solutions by animal bones. Animal bones were found to be an efficient sorbent with the maximum experimentally determined sorption capacity in the range 29-194 mg g(-1) that depended on pH and temperature. The maximum experimentally determined sorption capacity was obtained at 50 degrees C, pH 5. Batch kinetics and equilibrium experiments were performed in order to investigate the influence of contact time, initial concentration of sorbate and sorbent, temperature and pH. It was found that sorption capacity increased with increase of Cr(III) concentration, temperature and initial pH of metal solution. Mathematical models describing kinetics and statics of sorption were proposed. It was found that process kinetics followed the pseudo-second-order pattern. The influence of sorbent concentration was described with Langmuir-type equation and the influence of sorbate concentration was described with empirical dependence. The models were positively verified.

Phytotoxic and genotoxic effects of ZnO nanoparticles on garlic (Allium sativum L.): a morphological study.

PubMed

Shaymurat, Talgar; Gu, Jianxiu; Xu, Changshan; Yang, Zhikun; Zhao, Qing; Liu, Yuxue; Liu, Yichun

2012-05-01

The effects of zinc oxide nanoparticles (ZnO NPs) on the root growth, root apical meristem mitosis and mitotic aberrations of garlic (Allium sativum L.) were investigated. ZnO NPs caused a concentration-dependent inhibition of root length. When treated with 50 mg/L ZnO NPs for 24 h, the root growth of garlic was completely blocked. The 50% inhibitory concentration (IC(50)) was estimated to be 15 mg/L. The mitosis index was also decreased in a concentration- and time-dependent manner. ZnO NPs also induced several kinds of mitotic aberrations, mainly consisted of chromosome stickiness, bridges, breakages and laggings. The total percentage of abnormal cells increased with the increase of ZnO NPs concentration and the prolongation of treatment time. The investigation provided new information for the possible genotoxic effects of ZnO NPs on plants.

Adsorption of goethite onto quartz and kaolinite

USGS Publications Warehouse

Goldberg, M.C.; Weiner, Eugene R.; Boymel, P.M.

1984-01-01

The adsorption of colloidal goethite onto quartz and kaolinite substrates has been studied as a function of pH and NaCl concentration. Goethite adsorption was measured quantitatively by Fourier-transform infrared spectroscopy. The results indicate that adsorption onto both substrates is due primarily to coulombic forces; however, the pH dependence of adsorption is very different for the two substrates. This is explained by the fact that the surface charge on quartz is entirely pH-dependent, while kaolinite has surface faces which carry a permanent negative charge. Adsorption of goethite on to kaolinite increases markedly with increasing NaCl concentration, while adsorption onto quartz is relatively independent of NaCl concentration. This can be explained by the influence of NaCl concentration upon the development of surface charge on the substrates. A method is described for separating surface-bound goethite from free goethite.

Diuretic effects of medetomidine compared with xylazine in healthy dogs.

PubMed

Talukder, Md Hasanuzzaman; Hikasa, Yoshiaki

2009-07-01

This study aimed to investigate and compare the effects of medetomidine and xylazine on diuretic and hormonal variables in healthy dogs. Five dogs, used in each of 11 groups, were injected intramuscularly with physiological saline solution (control), 5, 10, 20, 40, and 80 microg/kg of medetomidine, and 0.25, 0.5, 1, 2, and 4 mg/kg of xylazine. Urine and blood samples were taken 11 times over 24 h. Both medetomidine and xylazine increased urine production in a dose-dependent manner up to 4 h after injection, but the increase was much less with medetomidine than with xylazine at the tested doses. Urine specific gravity, pH, osmolality, and concentrations of creatinine, sodium, potassium, chloride, and arginine vasopressin (AVP) were decreased in a dose-dependent manner with both medetomidine and xylazine. Plasma osmolality and concentrations of sodium, potassium, and chloride were increased significantly with both drugs. Total amounts of urine AVP excreted and plasma AVP concentrations were significantly decreased by higher doses of medetomidine but were not significantly decreased by xylazine. Higher doses of both drugs significantly increased the plasma concentration of atrial natriuretic peptide (ANP), but the effect was greater with medetomidine than with xylazine. The results revealed that both drugs induce a profound diuresis, but medetomidine's effect is less dose-dependent than xylazine's effect. Although changes in plasma concentrations of AVP and ANP may partially influence the diuresis induced by medetomidine, other factors may be involved in the mechanism of the diuretic response to both drugs. Thus, both agents can be used clinically for transient but effective diuresis accompanied by sedation.

The effect of alcohols on red blood cell mechanical properties and membrane fluidity depends on their molecular size.

PubMed

Sonmez, Melda; Ince, Huseyin Yavuz; Yalcin, Ozlem; Ajdžanović, Vladimir; Spasojević, Ivan; Meiselman, Herbert J; Baskurt, Oguz K

2013-01-01

The role of membrane fluidity in determining red blood cell (RBC) deformability has been suggested by a number of studies. The present investigation evaluated alterations of RBC membrane fluidity, deformability and stability in the presence of four linear alcohols (methanol, ethanol, propanol and butanol) using ektacytometry and electron paramagnetic resonance (EPR) spectroscopy. All alcohols had a biphasic effect on deformability such that it increased then decreased with increasing concentration; the critical concentration for reversal was an inverse function of molecular size. EPR results showed biphasic changes of near-surface fluidity (i.e., increase then decrease) and a decreased fluidity of the lipid core; rank order of effectiveness was butanol > propanol > ethanol > methanol, with a significant correlation between near-surface fluidity and deformability (r = 0.697; p<0.01). The presence of alcohol enhanced the impairment of RBC deformability caused by subjecting cells to 100 Pa shear stress for 300 s, with significant differences from control being observed at higher concentrations of all four alcohols. The level of hemolysis was dependent on molecular size and concentration, whereas echinocytic shape transformation (i.e., biconcave disc to crenated morphology) was observed only for ethanol and propanol. These results are in accordance with available data obtained on model membranes. They document the presence of mechanical links between RBC deformability and near-surface membrane fluidity, chain length-dependence of the ability of alcohols to alter RBC mechanical behavior, and the biphasic response of RBC deformability and near-surface membrane fluidity to increasing alcohol concentrations.

The Effect of Alcohols on Red Blood Cell Mechanical Properties and Membrane Fluidity Depends on Their Molecular Size

PubMed Central

Sonmez, Melda; Ince, Huseyin Yavuz; Yalcin, Ozlem; Ajdžanović, Vladimir; Spasojević, Ivan; Meiselman, Herbert J.; Baskurt, Oguz K.

2013-01-01

The role of membrane fluidity in determining red blood cell (RBC) deformability has been suggested by a number of studies. The present investigation evaluated alterations of RBC membrane fluidity, deformability and stability in the presence of four linear alcohols (methanol, ethanol, propanol and butanol) using ektacytometry and electron paramagnetic resonance (EPR) spectroscopy. All alcohols had a biphasic effect on deformability such that it increased then decreased with increasing concentration; the critical concentration for reversal was an inverse function of molecular size. EPR results showed biphasic changes of near-surface fluidity (i.e., increase then decrease) and a decreased fluidity of the lipid core; rank order of effectiveness was butanol > propanol > ethanol > methanol, with a significant correlation between near-surface fluidity and deformability (r = 0.697; p<0.01). The presence of alcohol enhanced the impairment of RBC deformability caused by subjecting cells to 100 Pa shear stress for 300 s, with significant differences from control being observed at higher concentrations of all four alcohols. The level of hemolysis was dependent on molecular size and concentration, whereas echinocytic shape transformation (i.e., biconcave disc to crenated morphology) was observed only for ethanol and propanol. These results are in accordance with available data obtained on model membranes. They document the presence of mechanical links between RBC deformability and near-surface membrane fluidity, chain length-dependence of the ability of alcohols to alter RBC mechanical behavior, and the biphasic response of RBC deformability and near-surface membrane fluidity to increasing alcohol concentrations. PMID:24086751

Cl(-) concentration dependence of photovoltage generation by halorhodopsin from Halobacterium salinarum.

PubMed Central

Muneyuki, Eiro; Shibazaki, Chie; Wada, Yoichiro; Yakushizin, Manabu; Ohtani, Hiroyuki

2002-01-01

The photovoltage generation by halorhodopsin from Halobacterium salinarum (shR) was examined by adsorbing shR-containing membranes onto a thin polymer film. The photovoltage consisted of two major components: one with a sub-millisecond range time constant and the other with a millisecond range time constant with different amplitudes, as previously reported. These components exhibited different Cl(-) concentration dependencies (0.1-9 M). We found that the time constant for the fast component was relatively independent of the Cl(-) concentration, whereas the time constant for the slow component increased sigmoidally at higher Cl(-) concentrations. The fast and the slow processes were attributed to charge (Cl(-)) movements within the protein and related to Cl(-) ejection, respectively. The laser photolysis studies of shR-membrane suspensions revealed that they corresponded to the formation and the decay of the N intermediate. The photovoltage amplitude of the slow component exhibited a distorted bell-shaped Cl(-) concentration dependence, and the Cl(-) concentration dependence of its time constant suggested a weak and highly cooperative Cl(-)-binding site(s) on the cytoplasmic side (apparent K(D) of approximately 5 M and Hill coefficient > or =5). The Cl(-) concentration dependence of the photovoltage amplitude and the time constant for the slow process suggested a competition between spontaneous relaxation and ion translocation. The time constant for the relaxation was estimated to be >100 ms. PMID:12324398

Sulfate reduction in sulfuric material after re-flooding: Effectiveness of organic carbon addition and pH increase depends on soil properties.

PubMed

Yuan, Chaolei; Fitzpatrick, Rob; Mosley, Luke M; Marschner, Petra

2015-11-15

Sulfuric material is formed upon oxidation of sulfidic material; it is extremely acidic, and therefore, an environmental hazard. One option for increasing pH of sulfuric material may be stimulation of bacterial sulfate reduction. We investigated the effects of organic carbon addition and pH increase on sulfate reduction after re-flooding in ten sulfuric materials with four treatments: control, pH increase to 5.5 (+pH), organic carbon addition with 2% w/w finely ground wheat straw (+C), and organic carbon addition and pH increase (+C+pH). After 36 weeks, in five of the ten soils, only treatment +C+pH significantly increased the concentration of reduced inorganic sulfur (RIS) compared to the control and increased the soil pore water pH compared to treatment+pH. In four other soils, pH increase or/and organic carbon addition had no significant effect on RIS concentration compared to the control. The RIS concentration in treatment +C+pH as percentage of the control was negatively correlated with soil clay content and initial nitrate concentration. The results suggest that organic carbon addition and pH increase can stimulate sulfate reduction after re-flooding, but the effectiveness of this treatment depends on soil properties. Copyright © 2015 Elsevier B.V. All rights reserved.

Effects of turbulence on warm clouds and precipitation with various aerosol concentrations

NASA Astrophysics Data System (ADS)

Lee, Hyunho; Baik, Jong-Jin; Han, Ji-Young

2015-02-01

This study investigates the effects of turbulence-induced collision enhancement (TICE) on warm clouds and precipitation by changing the cloud condensation nuclei (CCN) number concentration using a two-dimensional dynamic model with bin microphysics. TICE is determined according to the Taylor microscale Reynolds number and the turbulent dissipation rate. The thermodynamic sounding used in this study is characterized by a warm and humid atmosphere with a capping inversion layer, which is suitable for simulating warm clouds. For all CCN concentrations, TICE slightly reduces the liquid water path during the early stage of cloud development and accelerates the onset of surface precipitation. However, changes in the rainwater path and in the amount of surface precipitation that are caused by TICE depend on the CCN concentrations. For high CCN concentrations, the mean cloud drop number concentration (CDNC) decreases and the mean effective radius increases due to TICE. These changes cause an increase in the amount of surface precipitation. However, for low CCN concentrations, changes in the mean CDNC and in the mean effective radius induced by TICE are small and the amount of surface precipitation decreases slightly due to TICE. A decrease in condensation due to the accelerated coalescence between droplets explains the surface precipitation decrease. In addition, an increase in the CCN concentration can lead to an increase in the amount of surface precipitation, and the relationship between the CCN concentration and the amount of surface precipitation is affected by TICE. It is shown that these results depend on the atmospheric relative humidity.

Electronic bandstructure of semiconductor dilute bismide structures

NASA Astrophysics Data System (ADS)

Erucar, T.; Nutku, F.; Donmez, O.; Erol, A.

2017-02-01

In this work electronic band structure of dilute bismide GaAs/GaAs1-xBix quantum well structures with 1.8% and 3.75% bismuth compositions have been investigated both experimentally and theoretically. Photoluminescence (PL) measurements reveal that effective bandgap of the samples decreases approximately 65 meV per bismuth concentration. Temperature dependence of the effective bandgap is obtained to be higher for the sample with higher bismuth concentration. Moreover, both asymmetric characteristic at the low energy tail of the PL and full width at half maximum (FWHM) of PL peak increase with increasing bismuth composition as a result of increased Bi related defects located above valence band (VB). In order to explain composition dependence of the effective bandgap quantitatively, valence band anti-crossing (VBAC) model is used. Bismuth composition and temperature dependence of effective bandgap in a quantum well structure is modeled by solving Schrödinger equation and compared with experimental PL data.

Benzodiazepine sensitivity in normal human subjects.

PubMed

Hommer, D W; Matsuo, V; Wolkowitz, O; Chrousos, G; Greenblatt, D J; Weingartner, H; Paul, S M

1986-06-01

Increasing intravenous doses of diazepam or placebo were administered to ten healthy normal volunteers, and the changes in saccadic eye velocity, self-rated sedation and anxiety, and plasma cortisol and growth hormone concentrations were measured. Diazepam administration (4.4 to 140 micrograms/kg, cumulative dose) resulted in a dose-dependent decrease in saccadic eye velocity and plasma cortisol level as well as a dose-dependent increase in self-rated sedation and plasma growth hormone level. Self-rated anxiety was unaffected in these relatively nonanxious subjects. The diazepam-induced changes in saccadic eye velocity, sedation, and growth hormone and cortisol levels were highly correlated with each other and with increasing plasma diazepam concentration. These results are consistent with a benzodiazepine receptor-mediated action of diazepam. The highly quantifiable and dose-dependent decrease in saccadic eye velocity by benzodiazepines should make this a useful measure of benzodiazepine receptor sensitivity in humans.

Interaction of silver nanoparticles with proteins: a characteristic protein concentration dependent profile of SPR signal.

PubMed

Banerjee, Victor; Das, K P

2013-11-01

Silver nanoparticles are finding increasing applications in biological systems, for example as antimicrobial agents and potential candidates for control drug release systems. In all such applications, silver nanoparticles interact with proteins and other biomolecules. Hence, the study of such interactions is of considerable importance. While BSA has been extensively used as a model protein for the study of interaction with the silver nanoparticles, studies using other proteins are rather limited. The interaction of silver nanoparticles with light leads to collective oscillation of the conducting electrons giving rise to surface plasmon resonance (SPR). Here, we have studied the protein concentration dependence of the SPR band profiles for a number of proteins. We found that for all the proteins, with increase in concentration, the SPR band intensity initially decreased, reaching minima and then increased again leading to a characteristic "dip and rise" pattern. Minimum point of the pattern appeared to be related to the isoelectric point of the proteins. Detailed dynamic light scattering and transmission electron microscopy studies revealed that the consistency of SPR profile was dependent on the average particle size and state of association of the silver nanoparticles with the change in the protein concentration. Fluorescence spectroscopic studies showed the binding constants of the proteins with the silver nanoparticles were in the nano molar range with more than one nanoparticle binding to protein molecule. Structural studies demonstrate that protein retains its native-like structure on the nanoparticle surface unless the molar ratio of silver nanoparticles to protein exceeds 10. Our study reveals that nature of the protein concentration dependent profile of SPR signal is a general phenomena and mostly independent of the size and structure of the proteins. Copyright © 2013 Elsevier B.V. All rights reserved.

Physiologic volume of phosphorus during hemodialysis: predictions from a pseudo one-compartment model.

PubMed

Leypoldt, John K; Akonur, Alp; Agar, Baris U; Culleton, Bruce F

2012-10-01

The kinetics of plasma phosphorus concentrations during hemodialysis (HD) are complex and cannot be described by conventional one- or two-compartment kinetic models. It has recently been shown by others that the physiologic (or apparent distribution) volume for phosphorus (Vr-P) increases with increasing treatment time and shows a large variation among patients treated by thrice weekly and daily HD. Here, we describe the dependence of Vr-P on treatment time and predialysis plasma phosphorus concentration as predicted by a novel pseudo one-compartment model. The kinetics of plasma phosphorus during conventional and six times per week daily HD were simulated as a function of treatment time per session for various dialyzer phosphate clearances and patient-specific phosphorus mobilization clearances (K(M)). Vr-P normalized to extracellular volume from these simulations were reported and compared with previously published empirical findings. Simulated results were relatively independent of dialyzer phosphate clearance and treatment frequency. In contrast, Vr-P was strongly dependent on treatment time per session; the increase in Vr-P with treatment time was larger for higher values of K(M). Vr-P was inversely dependent on predialysis plasma phosphorus concentration. There was significant variation among predicted Vr-P values, depending largely on the value of K(M). We conclude that a pseudo one-compartment model can describe the empirical dependence of the physiologic volume of phosphorus on treatment time and predialysis plasma phosphorus concentration. Further, the variation in physiologic volume of phosphorus among HD patients is largely due to differences in patient-specific phosphorus mobilization clearance. © 2012 The Authors. Hemodialysis International © 2012 International Society for Hemodialysis.

Speciation of trihalomethane mixtures for the Mississippi, Missouri, and Ohio Rivers

USGS Publications Warehouse

Rathbun, R.E.

1996-01-01

Trihalomethane formation potentials were determined for the chlorination of water samples from the Mississippi, Missouri, and Ohio Rivers. Samples were collected during the summer and fall of 1991 and the spring of 1992 at 12 locations on the Mississippi from New Orleans, LA, to Minneapolis, MN, and on the Missouri and Ohio 1.6 km upstream from their confluences with the Mississippi. Formation potentials were determined as a function of pH and initial free-chlorine concentration. Chloroform concentrations decreased with distance downstream and approximately paralleled the decrease of the dissolved organic-carbon concentration. Bromide concentrations were 3.7-5.7 times higher for the Missouri and 1.4-1.6 times higher for the Ohio than for the Mississippi above their confluences, resulting in an overall increase of the bromide concentration with distance downstream. Variations of the concentrations of the brominated trihalomethanes with distance downstream approximately paralleled the variation of the bromide concentration. Concentrations of all four trihalomethanes increased as the pH increased. Concentrations of chloroform and bromodichloromethane increased slightly and the concentration of bromoform decreased as the initial free-chlorine concentration increased; the chlorodibromomethane concentration had little dependence on the free-chlorine concentration.

Borderline maintenance of erythrocyte 2,3-diphosphoglycerate concentrations in normoxic type 1 (insulin dependent) diabetic subjects.

PubMed

Story, C J; Roberts, A P; Ryall, R G

1986-02-01

Erythrocyte 2,3-diphosphoglycerate and haemoglobin A1c concentrations were measured in 26 clinically normoxic patients with type 1 (insulin dependent) diabetes mellitus. The concentration of 2,3-diphosphoglycerate theoretically required to maintain normal erythrocyte oxygen delivery function in each subject was calculated and compared with the measured concentrations. In the majority of diabetic patients 2,3-diphosphoglycerate concentrations were sufficient to keep the erythrocyte oxygen dissociation curve within the normal range under otherwise normal blood conditions. There was, however, a minority of patients in which this was not true. It is concluded that the increased erythrocyte 2,3-diphosphoglycerate concentrations in clinically normoxic diabetic subjects are generally less than compensatory for the effect of haemoglobin A1c formation on the haemoglobin-oxygen dissociation curve.

Effect of dexamethasone on expression of glucocorticoid receptor in human monocyte cell line THP-1.

PubMed

Li, Bo; Bai, Xiangjun; Wanh, Haiping

2006-01-01

The effect of dexamethasone with different concentrations and different stimulating periods on the expression of glucocorticoid receptors (GRalpha, GRbeta) protein was investigated in human monocyte cell line THP-1. The cultured human monocyte line THP-1 cells were stimulated by dexamethasone with different concentrations and different periods. The expression of GRalpha and GRbeta protein was detected by Western blotting. The results showed that the expression of GRalpha and GRbeta was detected in the THP-1 cells. The quantity of GRalpha expression was reduced by dexamethasone under the same concentration with the prolongation of the stimulating periods. The quantity of GRbeta expression was increased by dexamethasone treatment in a time- and dose-dependent manner. It was concluded that dexamethasone stimulation time-dependently reduced the GRalpha expression in THP-1 cells. Dexamethasone stimulation time- and dose-dependently increased the GRbeta expression in THP-1 cells. The expression of GRalpha and GRbeta was regulated by glucocorticoid.

Growth promotion effect of steelmaking slag on Spirulina platensis

NASA Astrophysics Data System (ADS)

Nogami, R.; Tam, L. T.; Anh, H. T. L.; Quynh, H. T. H.; Thom, L. T.; Nhat, P. V.; Thu, N. T. H.; Hong, D. D.; Wakisaka, M.

2016-04-01

A growth promotion effect of steelmaking slag on Spirulina platensis M135 was investigated. The growth promotion effect was obtained that was 1.27 times greater than that obtained by the control by adding 500 mg L-1 of steelmaking slag and culturing for 60 days. The lipid content decreased in a concentration-dependent manner with steelmaking slag, whereas the carbohydrate content remained constant. The protein content of S. platensis M135 increased in a concentration-dependent manner with steelmaking slag when cultured at day 45. The superoxide dismutase activity of S. platensis M135 exhibited a decreasing trend in a time-dependent manner and an increasing trend in the control. The superoxide dismutase activity was lower than that of the control at day 1 but was higher at day 30. No genetic damage was observed up to 500 mg L-1 of steelmaking slag at 30 days of culture. Recovery from genetic damage was observed at 1,000 mg L-1 of steelmaking slag but not at higher concentrations.

Osmotic swelling of polyacrylate hydrogels in physiological salt solutions.

PubMed

Horkay, F; Tasaki, I; Basser, P J

2000-01-01

The swelling behavior of fully neutralized sodium polyacrylate gels was investigated in aqueous solutions of alkali metal (LiCl, NaCl, KCl, CsCl) and alkaline earth metal salts (CaCl2, SrCl2, BaCl2). The total salt concentration and the ratio of monovalent to divalent cations were varied in the biologically significant range. It is found that the concentrations of both monovalent and divalent cations vary continuously and smoothly in the gel despite the abrupt change in the gel volume. The individual elastic, mixing, and ionic contributions to the free energy of the gel were separately determined as a function of the degree of network swelling to elucidate the thermodynamics of swelling. Shear modulus measurements performed at different Ca2+ concentrations suggest that Ca2+ does not form stable cross-links between the polymer chains. At low and moderate swelling ratios the concentration dependence of the shear modulus follows a power law behavior, G variation of phi n, with n = 0.34 +/- 0.03. At high swelling degrees, however, the shear modulus increases with increasing swelling. The value of the Flory-Huggins interaction parameter, chi, determined from osmotic swelling pressure and shear modulus measurements, strongly depends on the ionic composition of the equilibrium solution and increases with increasing Ca2+ concentration.

The Effects of Ibogaine on Uterine Smooth Muscle Contractions: Relation to the Activity of Antioxidant Enzymes.

PubMed

Oreščanin-Dušić, Zorana; Tatalović, Nikola; Vidonja-Uzelac, Teodora; Nestorov, Jelena; Nikolić-Kokić, Aleksandra; Mijušković, Ana; Spasić, Mihajlo; Paškulin, Roman; Bresjanac, Mara; Blagojević, Duško

2018-01-01

Ibogaine is an indole alkaloid originally extracted from the root bark of the African rainforest shrub Tabernanthe iboga . It has been explored as a treatment for substance abuse because it interrupts drug addiction and relieves withdrawal symptoms. However, it has been shown that ibogaine treatment leads to a sharp and transient fall in cellular ATP level followed by an increase of cellular respiration and ROS production. Since contractile tissues are sensitive to changes in the levels of ATP and ROS, here we investigated an ibogaine-mediated link between altered redox homeostasis and uterine contractile activity. We found that low concentrations of ibogaine stimulated contractile activity in spontaneously active uteri, but incremental increase of doses inhibited it. Inhibitory concentrations of ibogaine led to decreased SOD1 and elevated GSH-Px activity, but doses that completely inhibited contractions increased CAT activity. Western blot analyses showed that changes in enzyme activities were not due to elevated enzyme protein concentrations but posttranslational modifications. Changes in antioxidant enzyme activities point to a vast concentration-dependent increase in H 2 O 2 level. Knowing that extracellular ATP stimulates isolated uterus contractility, while H 2 O 2 has an inhibitory effect, this concentration-dependent stimulation/inhibition could be linked to ibogaine-related alterations in ATP level and redox homeostasis.

The Effects of Ibogaine on Uterine Smooth Muscle Contractions: Relation to the Activity of Antioxidant Enzymes

PubMed Central

Paškulin, Roman

2018-01-01

Ibogaine is an indole alkaloid originally extracted from the root bark of the African rainforest shrub Tabernanthe iboga. It has been explored as a treatment for substance abuse because it interrupts drug addiction and relieves withdrawal symptoms. However, it has been shown that ibogaine treatment leads to a sharp and transient fall in cellular ATP level followed by an increase of cellular respiration and ROS production. Since contractile tissues are sensitive to changes in the levels of ATP and ROS, here we investigated an ibogaine-mediated link between altered redox homeostasis and uterine contractile activity. We found that low concentrations of ibogaine stimulated contractile activity in spontaneously active uteri, but incremental increase of doses inhibited it. Inhibitory concentrations of ibogaine led to decreased SOD1 and elevated GSH-Px activity, but doses that completely inhibited contractions increased CAT activity. Western blot analyses showed that changes in enzyme activities were not due to elevated enzyme protein concentrations but posttranslational modifications. Changes in antioxidant enzyme activities point to a vast concentration-dependent increase in H2O2 level. Knowing that extracellular ATP stimulates isolated uterus contractility, while H2O2 has an inhibitory effect, this concentration-dependent stimulation/inhibition could be linked to ibogaine-related alterations in ATP level and redox homeostasis. PMID:29599898

Physical and radiological properties of radiochromic gel as of its composition

NASA Astrophysics Data System (ADS)

Lee, Sang Hoon; Kim, Juree; Shim, Su Jung; Chang, Kyung Hwan; Lim, Sangwook; Huh, Hyun Do; Shin, Dong Oh; Cho, Sam Ju

2014-04-01

In the research, we evaluated the use of leuco crystal violet (LCV) gel as a dosimeter for therapeutic radiation by investigating its optical characteristics at various component concentrations. We also investigated the aging effect of the LCV gel at different beam energies, doserates, and dosing times to evaluate the LCV's applicability to radiation therapy. We confirmed that the optimal optical wavelength of the LCV gel dosimeter was 600 nm. The dose sensitivity increased with increasing concentration of LCV; however, the optimal concentration was 1 mM LCV because the transparency of the gel dosimeter is important for use in optical CT scanners. However, the dose sensitivity decreased with increasing concentration of trichloroacetic acid (TAA). Moreover, the transparency of LCV rapidly decreased because of the generation of a white precipitate at TAA concentrations below 25 mM. Thus, an optimal TAA concentration of 30 mM was used in this study. Triton X-100 (8 mM) was identified as the optimal reagent for determining the optimum gel transparency and dose sensitivity. Thus, we present an LCV gel dosimeter composed of 4% gelatin by mass, 1 mM LCV, 30 mM TAA, and 8-mM Triton X-100 for use with an optical CT scanner. We showed good dose linearity up to 30 Gy. There was a little doserate dependency at a beam energy of 6 MV while the doserate dependence was more than 4.2% at a beam energy of 10 MV. To evaluate the energy dependence of the LCV gel dosimeter, we irradiated it at 20 Gy by using 6 MV and 10 MV beams. At the high doserate, the difference in the dose energy dependence was relatively small at approximately 1%, but the difference increased to 4.6% at the low doserate. With respect to the radiation absorbance at a photon energy of 6 MV, the absorbance at an electron energy of 6 MeV decreased by 5.4%, and the absorbances at 9, 12, and 15 MeV increased by 3, 18.7, and 12.2%, respectively. Furthermore, the aging effect was larger in the low-dose group then in the high-dose group. Moreover, we observed that the absorbance between 24 and 48 h after irradiation increased by approximately 5% at 5 Gy. For gel groups tested at high doses, the aging effect was reduced by approximately 1%.

Evolution of Fermi Surface Properties in CexLa1-xB6 and PrxLa1-xB6

NASA Astrophysics Data System (ADS)

Endo, Motoki; Nakamura, Shintaro; Isshiki, Toshiyuki; Kimura, Noriaki; Nojima, Tsutomu; Aoki, Haruyoshi; Harima, Hisatomo; Kunii, Satoru

2006-11-01

We report the de Haas-van Alphen (dHvA) effect measurements of the Fermi surface properties in LaB6, CexLa1-xB6 (x = 0.1, 0.25, 0.5, 0.75, 1.0) and PrxLa1-xB6 (x = 0.25, 0.5, 0.75, 1.0) with particular attention to the spin dependence of the Fermi surface properties. The Fermi surface shape and dimension of CexLa1-xB6 change considerably with Ce concentration, while those of PrxLa1-xB6 change very slightly up to x = 0.75, and in PrB6 the Fermi surface splits into the up and down spin Fermi surfaces. The effective mass of CexLa1-xB6 increases considerably with Ce concentration and is nearly proportional to the number of Ce ions, whereas that of PrxLa1-xB6 increases slightly with Pr concentration. In CexLa1-xB6 the effective mass depends very strongly on field and increases divergently with decreasing field, while that of PrxLa1-xB6 increases slightly with decreasing field. The contribution to the dHvA signal from the conduction electrons of one spin direction diminishes with Ce concentration and appears to disappear somewhere around x = 0.25--0.5. A weak spin dependence is also found in PrxLa1-xB6. The behaviors of CexLa1-xB6 and PrxLa1-xB6 are compared to discuss the origin of the spin dependence of the Fermi surface properties.

Effect of gold nanoparticles on the fluorescence excitation spectrum of α-fetoprotein: Local environment dependent fluorescence quenching

NASA Astrophysics Data System (ADS)

Li, Jian-jun; Chen, Yu; Wang, A.-qing; Zhu, Jian; Zhao, Jun-wu

2011-01-01

The effect of colloid gold nanoparticles (AuNPs) on the fluorescence excitation spectrum of α-fetoprotein (AFP) has been investigated experimentally. The excitation spectral peaks of AFP with low concentration from 0.01 ng ml -1 to 12 ng ml -1 increase monotonically with increasing of AFP concentration. When some gold colloids were added to the AFP solution, the excitation peak at 285 nm decreases distinctly. By comparing the excitation peak intensity of AFP solution with gold colloids and without gold colloids at different AFP concentrations, the quenching effect from gold nanoparticle was more effective at lower AFP concentration. So the range of concentration from 0.01 ng ml -1 to 0.09 ng ml -1 will be the potential range of applications because of the higher sensitivity. The physical origin based on local field effect was investigated to illuminate this local environment dependent fluorescence quenching. The changing extent of quenching with different AFP concentrations can be attributed to the nonlinear decreasing of the local field factor of gold nanoparticles as a function of environmental dielectric constant.

Lithium concentration dependent structure and mechanics of amorphous silicon

NASA Astrophysics Data System (ADS)

Sitinamaluwa, H. S.; Wang, M. C.; Will, G.; Senadeera, W.; Zhang, S.; Yan, C.

2016-06-01

A better understanding of lithium-silicon alloying mechanisms and associated mechanical behavior is essential for the design of Si-based electrodes for Li-ion batteries. Unfortunately, the relationship between the dynamic mechanical response and microstructure evolution during lithiation and delithiation has not been well understood. We use molecular dynamic simulations to investigate lithiated amorphous silicon with a focus to the evolution of its microstructure, phase composition, and stress generation. The results show that the formation of LixSi alloy phase is via different mechanisms, depending on Li concentration. In these alloy phases, the increase in Li concentration results in reduction of modulus of elasticity and fracture strength but increase in ductility in tension. For a LixSi system with uniform Li distribution, volume change induced stress is well below the fracture strength in tension.

Plasma cannabinoid concentrations during dronabinol pharmacotherapy for cannabis dependence.

PubMed

Milman, Garry; Bergamaschi, Mateus M; Lee, Dayong; Mendu, Damodara R; Barnes, Allan J; Vandrey, Ryan; Huestis, Marilyn A

2014-04-01

Recently, high-dose oral synthetic delta-9-tetrahydrocannabinol (THC) was shown to alleviate cannabis withdrawal symptoms. The present data describe cannabinoid pharmacokinetics in chronic, daily cannabis smokers who received high-dose oral THC pharmacotherapy and later a smoked cannabis challenge. Eleven daily cannabis smokers received 0, 30, 60, or 120 mg/d THC for four 5-day medication sessions, each separated by 9 days of ad libitum cannabis smoking. On the fifth day, participants were challenged with smoking one 5.9% THC cigarette. Plasma collected on the first and fifth days was quantified by two-dimensional gas chromatography mass spectrometer for THC, 11-hydroxy-THC (11-OH-THC), and 11-nor-9-carboxy-THC (THCCOOH). Linear ranges (ng/mL) were 0.5-100 for THC, 1-50 for 11-OH-THC, and 0.5-200 for THCCOOH. During placebo dosing, THC, 11-OH-THC, and THCCOOH concentrations consistently decreased, whereas all cannabinoids increased dose dependently during active dronabinol administration. THC increase over time was not significant after any dose, 11-OH-THC increased significantly during the 60- and 120-mg/d doses, and THCCOOH increased significantly only during the 120-mg/d dose. THC, 11-OH-THC, and THCCOOH concentrations peaked within 0.25 hours after cannabis smoking, except after 120 mg/d THC when THCCOOH peaked 0.5 hours before smoking. The significant withdrawal effects noted during placebo dronabinol administration were supported by significant plasma THC and 11-OH-THC concentration decreases. During active dronabinol dosing, significant dose-dependent increases in THC and 11-OH-THC concentrations support withdrawal symptom suppression. THC concentrations after cannabis smoking were only distinguishable from oral THC doses for 1 hour, too short a period to feasibly identify cannabis relapse. THCCOOH/THC ratios were higher 14 hours after overnight oral dronabinol abstinence but cannot distinguish oral THC dosing from the smoked cannabis intake.

Plasma Cannabinoid Concentrations during Dronabinol Pharmacotherapy for Cannabis Dependence

PubMed Central

Milman, Garry; Bergamaschi, Mateus M.; Lee, Dayong; Mendu, Damodara R.; Barnes, Allan J.; Vandrey, Ryan; Huestis, Marilyn A.

2013-01-01

Background Recently, high-dose oral synthetic delta-9-tetrahydrocannabinol (THC) was shown to alleviate cannabis withdrawal symptoms. The present data describe cannabinoid pharmacokinetics in chronic daily cannabis smokers who received high-dose oral THC pharmacotherapy and later, a smoked cannabis challenge. Methods 11 daily cannabis smokers received 0, 30, 60, or 120 mg/day THC for four 5-day medication sessions, each separated by 9-days of ad-libitum cannabis smoking. On the 5th day, participants were challenged with smoking one 5.9% THC cigarette. Plasma collected on the 1st and 5th days was quantified by GC-GC-MS for THC, 11-hydroxy-THC (11-OH-THC), and 11-nor-9-carboxy-THC (THCCOOH). Linear ranges (ng/mL) were 0.5–100 for THC, 1–50 11-OH-THC, and 0.5–200 THCCOOH. Results During placebo dosing, THC, 11-OH-THC and THCCOOH concentrations consistently decreased, while all cannabinoids increased dose-dependently during active dronabinol administration. THC increase over time was not significant after any dose, 11-OH-THC increased significantly during 60 and 120 mg/day doses, and THCCOOH increased significantly only during the 120 mg/day dose. THC and 11-OH-THC, and THCCOOH concentrations peaked within 0.25 h after cannabis smoking, except after 120 mg/day THC when THCCOOH peaked 0.5 h before smoking. Conclusions The significant withdrawal effects noted during placebo dronabinol administration were supported by significant plasma THC and 11-OH-THC concentration decreases. During active dronabinol dosing, significant dose-dependent increases in THC and 11-OH-THC concentrations support withdrawal symptom suppression. THC concentrations after cannabis smoking were only distinguishable from oral THC doses for 1 h, too short a period to feasibly identify cannabis relapse. THCCOOH/THC ratios were higher 14 h after overnight oral dronabinol abstinence, but cannot distinguish oral THC dosing from smoked cannabis intake. PMID:24067260

Tributyltin-induced endoplasmic reticulum stress and its Ca{sup 2+}-mediated mechanism

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

Isomura, Midori; Kotake, Yaichiro, E-mail: yaichiro@hiroshima-u.ac.jp; Masuda, Kyoichi

2013-10-01

Organotin compounds, especially tributyltin chloride (TBT), have been widely used in antifouling paints for marine vessels, but exhibit various toxicities in mammals. The endoplasmic reticulum (ER) is a multifunctional organelle that controls post-translational modification and intracellular Ca{sup 2+} signaling. When the capacity of the quality control system of ER is exceeded under stress including ER Ca{sup 2+} homeostasis disruption, ER functions are impaired and unfolded proteins are accumulated in ER lumen, which is called ER stress. Here, we examined whether TBT causes ER stress in human neuroblastoma SH-SY5Y cells. We found that 700 nM TBT induced ER stress markers suchmore » as CHOP, GRP78, spliced XBP1 mRNA and phosphorylated eIF2α. TBT also decreased the cell viability both concentration- and time-dependently. Dibutyltin and monobutyltin did not induce ER stress markers. We hypothesized that TBT induces ER stress via Ca{sup 2+} depletion, and to test this idea, we examined the effect of TBT on intracellular Ca{sup 2+} concentration using fura-2 AM, a Ca{sup 2+} fluorescent probe. TBT increased intracellular Ca{sup 2+} concentration in a TBT-concentration-dependent manner, and Ca{sup 2+} increase in 700 nM TBT was mainly blocked by 50 μM dantrolene, a ryanodine receptor antagonist (about 70% inhibition). Dantrolene also partially but significantly inhibited TBT-induced GRP78 expression and cell death. These results suggest that TBT increases intracellular Ca{sup 2+} concentration by releasing Ca{sup 2+} from ER, thereby causing ER stress. - Highlights: • We established that tributyltin induces endoplasmic reticulum (ER) stress. • Tributyltin induces ER stress markers in a concentration-dependent manner. • Tributyltin increases Ca{sup 2+} release from ER, thereby causing ER stress. • Dibutyltin and monobutyltin did not increase GRP78 or intracellular Ca{sup 2+}.« less

Dependence of Initial Oxygen Concentration on Ozone Yield Using Inductive Energy Storage System Pulsed Power Generator

NASA Astrophysics Data System (ADS)

Go, Tomio; Tanaka, Yasushi; Yamazaki, Nobuyuki; Mukaigawa, Seiji; Takaki, Koichi; Fujiwara, Tamiya

Dependence of initial oxygen concentration on ozone yield using streamer discharge reactor driven by an inductive energy storage system pulsed power generator is described in this paper. Fast recovery type diodes were employed as semiconductor opening switch to interrupt a circuit current within 100 ns. This rapid current change produced high-voltage short pulse between a secondary energy storage inductor. The repetitive high-voltage short pulse was applied to a 1 mm diameter center wire electrode placed in a cylindrical pulse corona reactor. The streamer discharge successfully occurred between the center wire electrode and an outer cylinder ground electrode of 2 cm inner diameter. The ozone was produced with the streamer discharge and increased with increasing pulse repetition rate. The ozone yield changed in proportion to initial oxygen concentration contained in the injected gas mixture at 800 ns forward pumping time of the current. However, the decrease of the ozone yield by decreasing oxygen concentration in the gas mixture at 180 ns forward pumping time of the current was lower than the decrease at 800 ns forward pumping time of the current. This dependence of the initial oxygen concentration on ozone yield at 180 ns forward pumping time is similar to that of dielectric barrier discharge reactor.

The effect of isoenzyme-selective PDE inhibitors on methacholine-induced contraction of guinea-pig and rat ileum.

PubMed Central

Tomkinson, A.; Raeburn, D.

1996-01-01

1. We have examined the effects of the isoenzyme-selective phosphodiesterase (PDE) inhibitors, vinpocetine (type 1), siguazodan (type 3), rolipram (type 4) and zaprinast (type 5) and the non-selective PDE inhibitor enprofylline on methacholine (MCh) contractile concentration-response curves on guinea-pig and rat isolated ileum. 2. In guinea-pig ileum, vinpocetine (10-300 microM), zaprinast (1-300 microM) and enprofylline (100-1000 microM) produced a concentration-dependent depression of the maximum response (Emax) to MCh only without effect on the MCh EC50 values (rank order of potency: zaprinast > vinpocetine > enprofylline). In contrast, siguazodan (10-300 microM) and rolipram (10-300 microM) produced a rightward displacement of the MCh concentration-response curve (increase in EC50: rank order; rolipram > siguazodan), with effects on the MCh maximum seen only at higher concentrations. 3. In the rat ileum, vinpocetine (10-300 microM), zaprinast (0.1-300 microM) and enprofylline (100-1000 microM) caused depression of the MCh maximum contraction (rank order: zaprinast > vinpocetine > enprofylline). Low concentrations of rolipram and siguazodan had no significant effect on the MCh maximum. In the presence of higher concentrations (> 100 microM) of rolipram and siguazodan, a maximum response was not achieved at the highest concentration of MCh tested. As in the guinea-pig ileum, only rolipram (10-300 microM) and siguazodan (10-300 microM) produced a significant, concentration-dependent, rightward displacement of the MCh concentration-response curve (increase in EC50: rank order: rolipram > siguazodan). 4. In the guinea-pig ileum, isoprenaline (0.1 microM) produced a rightward displacement (approximately 3 fold) of the MCh concentration-response curve, accompanied by a significant depression of the maximum response. Increasing the isoprenaline concentration (1 microM) had no further effect on either parameter. Sodium nitroprusside (SNP, > or = 10 microM) produced a concentration-dependent depression of the MCh maximum without an effect on the EC50. 5. In the rat ileum, isoprenaline (1 microM) produced a concentration-dependent rightward displacement (approximately 2.8 fold) of the MCh concentration-response curve with depression of the MCh maximum at higher (> or = 100 microM) concentrations. SNP produced depression of the MCh maximum at a concentration of 10 microM and above. Effects on the MCh EC50 were seen only at 100 and 300 microM. 6. In guinea-pig ileum, isoprenaline (0.1 microM) in combination with rolipram (10 microM) further increased the MCh EC50 and reduced the MCh maximum. The combination of SNP (10 microM) with zaprinast (0.1 microM) produced no further significant effect than SNP alone. 7. In rat ileum, isoprenaline (1 microM) in combination with rolipram (10 microM) further increased the EC50 and reduced the maximum. SNP (10 microM) had no significant effect on either the MCh maximum or EC50. A combination with zaprinast (1 microM) had no further effect. 8. In conclusion, all the PDE inhibitors tested produced a concentration-dependent inhibition of the MCh concentration-response curve, indicating a modulator role for the PDE isoenzymes in gastrointestinal smooth muscle contractility. The PDE inhibitors that elevate cyclic GMP produced a depression of the MCh maximum response only, whilst those that elevate cyclic AMP produced a rightward displacement of the MCh concentration-response curve. This was confirmed by the use of isoprenaline and SNP. This difference in the type of inhibition produced by these PDE isoenzyme inhibitors may reflect a different intracellular site/mechanism by which the cyclic AMP- and cyclic GMP-activated kinases act functionally to antagonize the contractile response. PMID:8864552

Structure and phase transitions of asphaltenes in solutions

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

Tar, M.M. de; Sheu, E.Y.; Storm, D.A.

The authors investigated the rheological properties of two vacuum resid fractions in a series of solvents. The authors measured the viscosity as a function of concentration and temperature respectively. In this study, two aspects were focused: (1) the concentration dependence of viscosity for the pentane soluble fractions in a series of n-alkane solvents for study of the particle structure, and (2) the temperature dependence of viscosity of the heptane insoluble fraction in toluene at various concentrations for the study of the phase transitions. From their results it was found that all the systems studied are Newtonian. The results for (1)more » show that the particles are approximately spherical and as the carbon number of the n-alkane solvent increases, the quality of the solvent increases, thereby increasing the particle solvation. This result is consistent with that reported in a recent paper by Ali and Saleem. Also, the particles were found to behave similarly to colloidal particles. As for (2), a glass-like transition was observed at 50% concentration (0.31 volume fraction) with glass transition temperature at about 254 K, while no structural or phase transitions were observed for concentrations below 50%.« less

Role of protein concentration and protein-saliva interactions in the astringency of whey proteins at low pH.

PubMed

Kelly, M; Vardhanabhuti, B; Luck, P; Drake, M A; Osborne, J; Foegeding, E A

2010-05-01

Whey protein beverages are adjusted to pH <4.5 to enhance clarity and stability, but this pH level is also associated with increased astringency. The goal of this investigation was to determine the effects of protein concentration on astringency and interactions between whey and salivary proteins. Whey protein beverages containing 0.25 to 13% (wt/wt) beta-lactoglobulin and 0.017% (wt/wt) sucralose at pH 2.6 to 4.2 were examined using descriptive sensory analysis. Controls were similar pH phosphate buffers at phosphate concentrations equivalent to the amount of phosphoric acid required to adjust the pH of the protein solution. Changes in astringency with protein concentration depended on pH. At pH 3.5, astringency significantly increased with protein concentration from 0.25 to 4% (wt/wt) and then remained constant from 4 to 13% (wt/wt). Conversely, at pH 2.6, astringency decreased with an increase in protein concentration [0.5-10% (wt/wt)]. This suggests a complex relationship that includes pH and buffering capacity of the beverages. Furthermore, saliva flow rates increased with increasing protein concentrations, showing that the physiological conditions in the mouth change with protein concentration. Maximum turbidity of whey protein-saliva mixtures was observed between pH 4.6 and 5.2. Both sensory evaluation and in vitro study of interactions between beta-LG and saliva indicate that astringency of whey proteins is a complex process determined by the extent of aggregation occurring in the mouth, which depends on the whey protein beverage pH and buffering capacity in addition to saliva flow rate. Copyright 2010 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Stiffness of Ca(2+)-pectin gels: combined effects of degree and pattern of methylesterification for various Ca(2+) concentrations.

PubMed

Ngouémazong, Doungla E; Jolie, Ruben P; Cardinaels, Ruth; Fraeye, Ilse; Van Loey, Ann; Moldenaers, Paula; Hendrickx, Marc

2012-02-01

The influence of the degree and pattern of methylesterification (DM and PM, respectively) on the stiffness of Ca(2+)-pectin gels is extensively examined, at various Ca(2+) concentrations. Accordingly, a highly methyl-esterified pectin was selectively de-esterified using NaOH, plant or fungal pectin methylesterase in order to produce series of pectins with varied pattern and broad ranges of methylesterification. The PM was quantified as absolute degree of blockiness (DB(abs)). Ca(2+)-pectin gels were prepared at various Ca(2+) concentrations. Gel stiffness (G' at 1rad/s) was determined and mapped out as a function of DM, DB(abs) and Ca(2+) concentration. At low Ca(2+) concentrations, G' depends on polymer's DM and DB(abs). At high Ca(2+) concentrations, a master curve is obtained over a wide range of DM, irrespective of DB(abs). Depending on methylesterification pattern, increase of G' is related not only to an increase in the number of junction zones per pectin chain, but also to an increase in the size of junction zones and the number of dimerised chains occurring in the gels. These results provide a detailed insight into the occurrence of junction zones in Ca(2+)-pectin gels. Copyright © 2011 Elsevier Ltd. All rights reserved.

Analysis and effects of cytosolic free calcium increases in response to elicitors in Nicotiana plumbaginifolia cells.

PubMed

Lecourieux, David; Mazars, Christian; Pauly, Nicolas; Ranjeva, Raoul; Pugin, Alain

2002-10-01

Cell suspensions obtained from Nicotiana plumbaginifolia plants stably expressing the apoaequorin gene were used to analyze changes in cytosolic free calcium concentrations ([Ca(2+)](cyt)) in response to elicitors of plant defenses, particularly cryptogein and oligogalacturonides. The calcium signatures differ in lag time, peak time, intensity, and duration. The intensities of both signatures depend on elicitor concentration and extracellular calcium concentration. Cryptogein signature is characterized by a long-sustained [Ca(2+)](cyt) increase that should be responsible for sustained mitogen-activated protein kinase activation, microtubule depolymerization, defense gene activation, and cell death. The [Ca(2+)](cyt) increase in elicitor-treated cells first results from a calcium influx, which in turns leads to calcium release from internal stores and additional Ca(2+) influx. H(2)O(2) resulting from the calcium-dependent activation of the NADPH oxidase also participates in [Ca(2+)](cyt) increase and may activate calcium channels from the plasma membrane. Competition assays with different elicitins demonstrate that [Ca(2+)](cyt) increase is mediated by cryptogein-receptor interaction.

Analysis and Effects of Cytosolic Free Calcium Increases in Response to Elicitors in Nicotiana plumbaginifolia Cells

PubMed Central

Lecourieux, David; Mazars, Christian; Pauly, Nicolas; Ranjeva, Raoul; Pugin, Alain

2002-01-01

Cell suspensions obtained from Nicotiana plumbaginifolia plants stably expressing the apoaequorin gene were used to analyze changes in cytosolic free calcium concentrations ([Ca2+]cyt) in response to elicitors of plant defenses, particularly cryptogein and oligogalacturonides. The calcium signatures differ in lag time, peak time, intensity, and duration. The intensities of both signatures depend on elicitor concentration and extracellular calcium concentration. Cryptogein signature is characterized by a long-sustained [Ca2+]cyt increase that should be responsible for sustained mitogen-activated protein kinase activation, microtubule depolymerization, defense gene activation, and cell death. The [Ca2+]cyt increase in elicitor-treated cells first results from a calcium influx, which in turns leads to calcium release from internal stores and additional Ca2+ influx. H2O2 resulting from the calcium-dependent activation of the NADPH oxidase also participates in [Ca2+]cyt increase and may activate calcium channels from the plasma membrane. Competition assays with different elicitins demonstrate that [Ca2+]cyt increase is mediated by cryptogein–receptor interaction. PMID:12368509

Lipotoxicity in HepG2 cells triggered by free fatty acids

PubMed Central

Yao, Hong-Rui; Liu, Jun; Plumeri, Daniel; Cao, Yong-Bing; He, Ting; Lin, Ling; Li, Yu; Jiang, Yuan-Ying; Li, Ji; Shang, Jing

2011-01-01

The goal of this study was to investigate the lipid accumulation and lipotoxicity of free fatty acids (FFAs) induced in HepG2 cells. HepG2 cells were co-incubated with various concentrations of FFAs for 24h and the intracellular lipid contents were observed by Oil Red O and Nile Red staining methods. The lipotoxicity of HepG2 cells were then detected by Hoechest 33342/PI, Annexin V-FITC/PI double-staining and 3-(4,5-dimethylthiazol-2-yl)-2,5-di phenyltetrazolium bromide (MTT) experiment tests. The experiments showed a lipid accumulation and lipotoxicity by increasing FFA concentration gradients. Through cell morphological observation and quantitative analysis, FFAs have shown to increase in a dose-dependent manner compared with the control group. The data collected from hoechst 33342/PI, annexin V-FITC/PI double staining and also MTT experiments showed that cell apoptosis and necrosis significantly increased with increasing FFA concentrations. Apoptosis was not obvious in the 1 mM FFAs-treated group compared to the other two groups. In a certain concentration range, FFAs induced intracellular lipid accumulation and lipotoxicity of HepG2 cells in a dose-dependent manner. PMID:21654881

Effect of water on structure and dynamics of [BMIM][PF6] ionic liquid: An all-atom molecular dynamics simulation investigation.

PubMed

Sharma, Anirban; Ghorai, Pradip Kr

2016-03-21

Composition dependent structural and dynamical properties of aqueous hydrophobic 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]) ionic liquid (IL) have been investigated by using all-atom molecular dynamics simulation. We observe that addition of water does not increase significant number of dissociated ions in the solution over the pure state. As a consequence, self-diffusion coefficient of the cation and anion is comparable to each other at all water concentration similar to that is observed for the pure state. Voronoi polyhedra analysis exhibits strong dependence on the local environment of IL concentration. Void and neck distributions in Voronoi tessellation are approximately Gaussian for pure IL but upon subsequent addition of water, we observe deviation from the Gaussian behaviour with an asymmetric broadening with long tail of exponential decay at large void radius, particularly at higher water concentrations. The increase in void space and neck size at higher water concentration facilitates ionic motion, thus, decreasing dynamical heterogeneity and IL reorientation time and increases self-diffusion coefficient significantly.

Effect of water on structure and dynamics of [BMIM][PF{sub 6}] ionic liquid: An all-atom molecular dynamics simulation investigation

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

Sharma, Anirban; Ghorai, Pradip Kr., E-mail: pradip@iiserkol.ac.in

2016-03-21

Composition dependent structural and dynamical properties of aqueous hydrophobic 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF{sub 6}]) ionic liquid (IL) have been investigated by using all-atom molecular dynamics simulation. We observe that addition of water does not increase significant number of dissociated ions in the solution over the pure state. As a consequence, self-diffusion coefficient of the cation and anion is comparable to each other at all water concentration similar to that is observed for the pure state. Voronoi polyhedra analysis exhibits strong dependence on the local environment of IL concentration. Void and neck distributions in Voronoi tessellation are approximately Gaussian for pure ILmore » but upon subsequent addition of water, we observe deviation from the Gaussian behaviour with an asymmetric broadening with long tail of exponential decay at large void radius, particularly at higher water concentrations. The increase in void space and neck size at higher water concentration facilitates ionic motion, thus, decreasing dynamical heterogeneity and IL reorientation time and increases self-diffusion coefficient significantly.« less

River chloride trends in snow-affected urban watersheds: increasing concentrations outpace urban growth rate and are common among all seasons

USGS Publications Warehouse

Corsi, Steven R.; De Cicco, Laura A.; Lutz, Michelle A.; Hirsch, Robert M.

2014-01-01

Chloride concentrations in northern U.S. included in this study have increased substantially over time with average concentrations approximately doubling from 1990 to 2011, outpacing the rate of urbanization in the northern U.S. Historical data were examined for 30 monitoring sites on 19 streams that had chloride concentration and flow records of 18 to 49 years. Chloride concentrations in most studied streams increased in all seasons (13 of 19 in all seasons; 16 of 19 during winter); maximum concentrations occurred during winter. Increasing concentrations during non-deicing periods suggest that chloride was stored in hydrologic reservoirs, such as the shallow groundwater system, during the winter and slowly released in baseflow throughout the year. Streamflow dependency was also observed with chloride concentrations increasing as streamflow decreased, a result of dilution during rainfall- and snowmelt-induced high-flow periods. The influence of chloride on aquatic life increased with time; 29% of sites studied exceeded the concentration for the USEPA chronic water quality criteria of 230 mg/L by an average of more than 100 individual days per year during 2006–2011. The rapid rate of chloride concentration increase in these streams is likely due to a combination of possible increased road salt application rates, increased baseline concentrations, and greater snowfall in the Midwestern U.S. during the latter portion of the study period.

River chloride trends in snow-affected urban watersheds: increasing concentrations outpace urban growth rate and are common among all seasons.

PubMed

Corsi, Steven R; De Cicco, Laura A; Lutz, Michelle A; Hirsch, Robert M

2015-03-01

Chloride concentrations in northern U.S. included in this study have increased substantially over time with average concentrations approximately doubling from 1990 to 2011, outpacing the rate of urbanization in the northern U.S. Historical data were examined for 30 monitoring sites on 19 streams that had chloride concentration and flow records of 18 to 49 years. Chloride concentrations in most studied streams increased in all seasons (13 of 19 in all seasons; 16 of 19 during winter); maximum concentrations occurred during winter. Increasing concentrations during non-deicing periods suggest that chloride was stored in hydrologic reservoirs, such as the shallow groundwater system, during the winter and slowly released in baseflow throughout the year. Streamflow dependency was also observed with chloride concentrations increasing as streamflow decreased, a result of dilution during rainfall- and snowmelt-induced high-flow periods. The influence of chloride on aquatic life increased with time; 29% of sites studied exceeded the concentration for the USEPA chronic water quality criteria of 230 mg/L by an average of more than 100 individual days per year during 2006-2011. The rapid rate of chloride concentration increase in these streams is likely due to a combination of possible increased road salt application rates, increased baseline concentrations, and greater snowfall in the Midwestern U.S. during the latter portion of the study period. Published by Elsevier B.V.

[Erythremia: the activity of erythrocyte antioxidant enzymes and the association with iron deficiency].

PubMed

Petukhov, V I; Kumerova, A O; Letse, A G; Silova, A A; Shkesters, A P; Krishchuna, M A; Mironova, N A

1997-01-01

Concentration of malonic dialdehyde (MDA) and activity of antioxidant enzymes G-6-PD, glutation peroxidase (GP), glutation reductase, catalase, superoxide dismutase were measured in red cells of patients with polycythemia vera. Plasmic ions Fe3+ were estimated by means of electron-paramagnetic resonance. MDA concentration and antioxidant enzymes (except GP) in polycythemia red cells were found increased, while the activity of selenium-dependent GP was reduced, the inhibition being greatest in severe iron deficiency. It is suggested that GP activity in red cells depends on both selenium levels in the body and concentrations of non-hematic iron.

Polylogarithmic equilibrium treatment of molecular aggregation and critical concentrations.

PubMed

Michel, Denis; Ruelle, Philippe

2017-02-15

A full equilibrium treatment of molecular aggregation is presented for prototypes of 1D and 3D aggregates, with and without nucleation. By skipping complex kinetic parameters like aggregate size-dependent diffusion, the equilibrium treatment allows us to predict directly time-independent quantities such as critical concentrations. The relationships between the macroscopic equilibrium constants for different paths are first established by statistical corrections and so as to comply with the detailed balance constraints imposed by nucleation, and the composition of the mixture resulting from homogeneous aggregation is then analyzed using a polylogarithmic function. Several critical concentrations are distinguished: the residual monomer concentration at equilibrium (RMC) and the critical nucleation concentration (CNC), which is the threshold concentration of total subunits necessary for initiating aggregation. When increasing the concentration of total subunits, the RMC converges more strongly to its asymptotic value, the equilibrium constant of depolymerization, for 3D aggregates and in the case of nucleation. The CNC moderately depends on the number of subunits in the nucleus, but sharply increases with the difference between the equilibrium constants of polymerization and nucleation. As the RMC and CNC can be numerically but not analytically determined, ansatz equations connecting them to thermodynamic parameters are proposed.

Concentration dependent refractive index of a binary mixture at high pressure.

PubMed

Croccolo, Fabrizio; Arnaud, Marc-Alexandre; Bégué, Didier; Bataller, Henri

2011-07-21

In the present work binary mixtures of varying concentrations of two miscible hydrocarbons, 1,2,3,4-tetrahydronaphtalene (THN) and n-dodecane (C12), are subjected to increasing pressure up to 50 MPa in order to investigate the dependence of the so-called concentration contrast factor (CF), i.e., (∂n/∂c)(p, T), on pressure level. The refractive index is measured by means of a Mach-Zehnder interferometer. The setup and experimental procedure are validated with different pure fluids in the same pressure range. The refractive index of the THN-C12 mixture is found to vary both over pressure and concentration, and the concentration CF is found to exponentially decrease as the pressure is increased. The measured values of the refractive index and the concentration CFs are compared with values obtained by two different theoretical predictions, the well-known Lorentz-Lorenz formula and an alternative one proposed by Looyenga. While the measured refractive indices agree very well with predictions given by Looyenga, the measured concentration CFs show deviations from the latter of the order of 6% and more than the double from the Lorentz-Lorenz predictions.

Enhancement of anti-Aeromonas salmonicida activity in Atlantic salmon (Salmo salar) macrophages by a mannose-binding lectin

USGS Publications Warehouse

Ottinger, C.A.; Johnson, S.C.; Ewart, K.V.; Brown, L.L.; Ross, N.W.

1999-01-01

We investigated the effects of a calcium-dependent mannose-binding lectin isolated from the serum of Atlantic salmon on Aeromonassalmonicida viability and the anti-A. salmonicida activity of Atlantic salmon macrophages. In the absence of other factors, binding of this lectin at concentrations of 0.8, 4.0 and 20.0 ng ml−1 to virulent A. salmonicida failed to significantly reduce (P>0.05) cell viability. However, binding of the lectin to A. salmonicida did result in significant (P≤0.05) dose-dependent increases in phagocytosis, and bactericidal activity. Significant increases (P≤0.05) were also observed in phagocyte respiratory burst activity within the lectin concentration range of 4.0–20.0 ng ml−1 but the stimulation was not dose dependent at these lectin concentrations. At the lowest lectin concentration tested (0.32 ng ml−1), a significant decrease (P≤0.05) in respiratory burst was observed. The structure and activity of this lectin are similar to that of mammalian mannose-binding lectins, which are known to play a pivotal role in innate immunity. The presence of this lectin may be an important defense mechanism against Gram-negative bacteria such as A. salmonicida.

The storage capacity of fluorine in olivine and pyroxene under upper mantle conditions

NASA Astrophysics Data System (ADS)

Grützner, Tobias; Kohn, Simon C.; Bromiley, David W.; Rohrbach, Arno; Berndt, Jasper; Klemme, Stephan

2017-07-01

We present new experimental results on the fluorine storage capacity of olivine and orthopyroxene in the Earth's mantle. Experiments were performed in the system MgO-SiO2 + MgF2 at temperatures between 1350 °C and 1700 °C and pressures up to 17 GPa. Electron microprobe measurements show that fluorine concentrations in olivine reach up to 5100 μg/g. The storage capacity of fluorine in olivine shows only a small pressure dependence but a strong temperature dependence with a positive correlation between increasing temperature and fluorine storage capacity. Fluorine concentrations found in enstatite are one order of magnitude smaller and reach up to 670 μg/g. Our data show that concentrations of fluorine in fluorine-saturated olivine are in the same range as water concentrations in olivine. Nevertheless, fluorine and water solubility in olivine show opposing behavior with increasing pressure and temperature. The fluorine solubility in olivine increases with increasing temperature but is not much affected by pressure. In contrast, water solubility in olivine has previously been shown to decrease with increasing temperature and increase with increasing pressure. Our experiments show that nominally fluorine-free minerals like forsterite and enstatite are capable of storing the entire fluorine budget of the upper mantle, without the need to invoke accessory phases such as apatite or amphibole.

Different patterns of nuclear and mitochondrial penetration by the G3 PAMAM dendrimer and its biotin–pyridoxal bioconjugate BC-PAMAM in normal and cancer cells in vitro

PubMed Central

Uram, Łukasz; Szuster, Magdalena; Filipowicz, Aleksandra; Gargasz, Krzysztof; Wołowiec, Stanisław; Wałajtys-Rode, Elżbieta

2015-01-01

The intracellular localization and colocalization of a fluorescently labeled G3 amine-terminated cationic polyamidoamine (PAMAM) dendrimer and its biotin–pyridoxal (BC-PAMAM) bioconjugate were investigated in a concentration-dependent manner in normal human fibroblast (BJ) and squamous epithelial carcinoma (SCC-15) cell lines. After 24 hours treatment, both cell lines revealed different patterns of intracellular dendrimer accumulation depending on their cytotoxic effects. Cancer cells exhibited much higher (20-fold) tolerance for native PAMAM treatment than fibroblasts, whereas BC-PAMAM was significantly toxic only for fibroblasts at 50 µM concentration. Fibroblasts accumulated the native and bioconjugated dendrimers in a concentration-dependent manner at nontoxic range of concentration, with significantly lower bioconjugate loading. After reaching the cytotoxicity level, fluorescein isothiocyanate-PAMAM accumulation remains at high, comparable level. In cancer cells, native PAMAM loading at higher, but not cytotoxic concentrations, was kept at constant level with a sharp increase at toxic concentration. Mander’s coefficient calculated for fibroblasts and cancer cells confirmed more efficient native PAMAM penetration as compared to BC-PAMAM. Significant differences in nuclear dendrimer penetration were observed for both cell lines. In cancer cells, PAMAM signals amounted to ~25%–35% of the total nuclei area at all investigated concentrations, with lower level (15%–25%) observed for BC-PAMAM. In fibroblasts, the dendrimer nuclear signal amounted to 15% at nontoxic and up to 70% at toxic concentrations, whereas BC-PAMAM remained at a lower concentration-dependent level (0.3%–20%). Mitochondrial localization of PAMAM and BC-PAMAM revealed similar patterns in both cell lines, depending on the extracellular dendrimer concentration, and presented significantly lower signals from BC-PAMAM, which correlated well with the cytotoxicity. PMID:26379435

New Insights into the Compositional Dependence of Li-Ion Transport in Polymer-Ceramic Composite Electrolytes.

PubMed

Zheng, Jin; Hu, Yan-Yan

2018-01-31

Composite electrolytes are widely studied for their potential in realizing improved ionic conductivity and electrochemical stability. Understanding the complex mechanisms of ion transport within composites is critical for effectively designing high-performance solid electrolytes. This study examines the compositional dependence of the three determining factors for ionic conductivity, including ion mobility, ion transport pathways, and active ion concentration. The results show that with increase in the fraction of ceramic Li 7 La 3 Zr 2 O 12 (LLZO) phase in the LLZO-poly(ethylene oxide) composites, ion mobility decreases, ion transport pathways transit from polymer to ceramic routes, and the active ion concentration increases. These changes in ion mobility, transport pathways, and concentration collectively explain the observed trend of ionic conductivity in composite electrolytes. Liquid additives alter ion transport pathways and increase ion mobility, thus enhancing ionic conductivity significantly. It is also found that a higher content of LLZO leads to improved electrochemical stability of composite electrolytes. This study provides insight into the recurring observations of compositional dependence of ionic conductivity in current composite electrolytes and pinpoints the intrinsic limitations of composite electrolytes in achieving fast ion conduction.

Nitric oxide signaling depends on biotin in Jurkat human lymphoma cells.

PubMed

Rodriguez-Melendez, Rocio; Zempleni, Janos

2009-03-01

Biotin affects gene expression through a diverse array of cell signaling pathways. Previous studies provided evidence that cGMP-dependent signaling also depends on biotin, but the mechanistic sequence of cGMP regulation by biotin is unknown. Here we tested the hypothesis that the effects of biotin in cGMP-dependent cell signaling are mediated by nitric oxide (NO). Human lymphoid (Jurkat) cells were cultured in media containing deficient (0.025 nmol/L), physiological (0.25 nmol/L), and pharmacological (10 nmol/L) concentrations of biotin for 5 wk. Both levels of intracellular biotin and NO exhibited a dose-dependent relationship in regard to biotin concentrations in culture media. Effects of biotin on NO levels were disrupted by the NO synthase (NOS) inhibitor N-monomethyl-arginine. Biotin-dependent production of NO was linked with biotin-dependent expression of endothelial and neuronal NOS, but not inducible NOS. Previous studies revealed that NO is an activator of guanylate cyclase. Consistent with these previous observations, biotin-dependent generation of NO increased the abundance of cGMP in Jurkat cells. Finally, the biotin-dependent generation of cGMP increased protein kinase G activity. Collectively, the results of this study are consistent with the hypothesis that biotin-dependent cGMP signaling in human lymphoid cells is mediated by NO.

Determination of the glass-transition temperature of proteins from a viscometric approach.

PubMed

Monkos, Karol

2015-03-01

All fully hydrated proteins undergo a distinct change in their dynamical properties at glass-transition temperature Tg. To determine indirectly this temperature for dry albumins, the viscosity measurements of aqueous solutions of human, equine, ovine, porcine and rabbit serum albumin have been conducted at a wide range of concentrations and at temperatures ranging from 278 K to 318 K. Viscosity-temperature dependence of the solutions is discussed on the basis of the three parameters equation resulting from Avramov's model. One of the parameter in the Avramov's equation is the glass-transition temperature. For all studied albumins, Tg of a solution monotonically increases with increasing concentration. The glass-transition temperature of a solution depends both on Tg for a dissolved dry protein Tg,p and water Tg,w. To obtain Tg,p for each studied albumin the modified Gordon-Taylor equation was applied. This equation describes the dependence of Tg of a solution on concentration, and Tg,p and a parameter depending on the strength of the protein-solvent interaction are the fitting parameters. Thus determined the glass-transition temperature for the studied dry albumins is in the range (215.4-245.5)K. Copyright © 2014 Elsevier B.V. All rights reserved.

Nano porous silicon microcavity sensor for determination organic solvents and pesticide in water

NASA Astrophysics Data System (ADS)

Pham, Van Hoi; Van Nguyen, Thuy; Nguyen, The Anh; Pham, Van Dai; Bui, Huy

2014-12-01

In this paper we present a sensing method using nano-porous silicon microcavity sensor, which was developed in order to obtain simultaneous determination of two volatile substances with different solvent concentrations as well as very low pesticide concentration in water. The temperature of the solution and the velocity of the air stream flowing through the solution have been used to control the response of the sensor for different solvent solutions. We study the dependence of the cavity-resonant wavelength shift on solvent concentration, velocity of the airflow and solution temperature. The wavelength shift depends linearly on concentration and increases with solution temperature and velocity of the airflow. The dependence of the wavelength shift on the solution temperature in the measurement contains properties of the temperature dependence of the solvent vapor pressure, which characterizes each solvent. As a result, the dependence of the wavelength shift on the solution temperature discriminates between solutions of ethanol and acetone with different concentrations. This suggests a possibility for the simultaneous determination of the volatile substances and their concentrations. On the other hand, this method is able to detect the presence of atrazine pesticide by the shift of the resonant wavelength, with good sensitivity (0.3 nm pg-1 ml) and limit of detection (LOD) (0.8-1.4 pg ml-1), that we tested for concentrations in the range from 2.15 to 21.5 pg ml-1, which is the range useful for monitoring acceptable water for human consumption.

Concentration-jump analysis of voltage-dependent conductances activated by glutamate and kainate in neurons of the avian cochlear nucleus.

PubMed Central

Raman, I M; Trussell, L O

1995-01-01

We have examined the mechanisms underlying the voltage sensitivity of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate receptors in voltage-clamped outside-out patches and whole cells taken from the nucleus magnocellularis of the chick. Responses to either glutamate or kainate had outwardly rectifying current-voltage relations. The rate and extent of desensitization during prolonged exposure to agonist, and the rate of deactivation after brief exposure to agonist, decreased at positive potentials, suggesting that a kinetic transition was sensitive to membrane potential. Voltage dependence of the peak conductance and of the deactivation kinetics persisted when desensitization was reduced with aniracetam or blocked with cyclothiazide. Furthermore, the rate of recovery from desensitization to glutamate was not voltage dependent. Upon reduction of extracellular divalent cation concentration, kainate-evoked currents increased but preserved rectifying current-voltage relations. Rectification was strongest at lower kainate concentrations. Surprisingly, nonstationary variance analysis of desensitizing responses to glutamate or of the current deactivation after kainate removal revealed an increase in the mean single-channel conductance with more positive membrane potentials. These data indicate that the rectification of the peak response to a high agonist concentration reflects an increase in channel conductance, whereas rectification of steady-state current is dominated by voltage-sensitive channel kinetics. Images FIGURE 2 FIGURE 3 PMID:8580330

The vesicle-to-micelle transition of phosphatidylcholine vesicles induced by nonionic detergents: effects of sodium chloride, sucrose and urea.

PubMed

Walter, A; Kuehl, G; Barnes, K; VanderWaerdt, G

2000-11-23

The vesicle-to-micelle transition of egg phosphatidylcholine LUVs induced by octylglucoside was studied in buffers with 0-4 M sodium chloride, sucrose or urea. We used both light scattering and fluorescent probes to follow the lipid-detergent complexes in these buffers. The vesicle-to-micelle transition process was fundamentally the same in each solute. However, the detergent-to-lipid ratio required for micelle formation shifted in ways that depended on the aqueous solute. The partitioning of octylglucoside between the vesicles and the aqueous phase was primarily determined by the change in its critical micelle concentration (cmc) induced by each solute. Specifically, the cmc decreased in high salt and sucrose buffers but increased in high concentrations of urea. Cmc for two additional nonionic detergents, decyl- and dodecyl-maltoside, and three zwittergents (3-12, 3-14 and 3-16) were determined as a function of concentration for each of the solutes. In all cases NaCl and sucrose decreased the solubility of the detergents, whereas urea increased their solubilities. The effects clearly depended on acyl chain length in urea-containing solutions, but this dependence was less clear with increasing NaCl and sucrose concentrations. The contributions of these solutes to solubility and to interfacial interactions in the bilayers, pure and mixed micelles are considered.

Diuretic effects of medetomidine compared with xylazine in healthy dogs

PubMed Central

Talukder, Md. Hasanuzzaman; Hikasa, Yoshiaki

2009-01-01

This study aimed to investigate and compare the effects of medetomidine and xylazine on diuretic and hormonal variables in healthy dogs. Five dogs, used in each of 11 groups, were injected intramuscularly with physiological saline solution (control), 5, 10, 20, 40, and 80 μg/kg of medetomidine, and 0.25, 0.5, 1, 2, and 4 mg/kg of xylazine. Urine and blood samples were taken 11 times over 24 h. Both medetomidine and xylazine increased urine production in a dose-dependent manner up to 4 h after injection, but the increase was much less with medetomidine than with xylazine at the tested doses. Urine specific gravity, pH, osmolality, and concentrations of creatinine, sodium, potassium, chloride, and arginine vasopressin (AVP) were decreased in a dose-dependent manner with both medetomidine and xylazine. Plasma osmolality and concentrations of sodium, potassium, and chloride were increased significantly with both drugs. Total amounts of urine AVP excreted and plasma AVP concentrations were significantly decreased by higher doses of medetomidine but were not significantly decreased by xylazine. Higher doses of both drugs significantly increased the plasma concentration of atrial natriuretic peptide (ANP), but the effect was greater with medetomidine than with xylazine. The results revealed that both drugs induce a profound diuresis, but medetomidine’s effect is less dose-dependent than xylazine’s effect. Although changes in plasma concentrations of AVP and ANP may partially influence the diuresis induced by medetomidine, other factors may be involved in the mechanism of the diuretic response to both drugs. Thus, both agents can be used clinically for transient but effective diuresis accompanied by sedation. PMID:19794896

Correlative and multivariate analysis of increased radon concentration in underground laboratory.

PubMed

Maletić, Dimitrije M; Udovičić, Vladimir I; Banjanac, Radomir M; Joković, Dejan R; Dragić, Aleksandar L; Veselinović, Nikola B; Filipović, Jelena

2014-11-01

The results of analysis using correlative and multivariate methods, as developed for data analysis in high-energy physics and implemented in the Toolkit for Multivariate Analysis software package, of the relations of the variation of increased radon concentration with climate variables in shallow underground laboratory is presented. Multivariate regression analysis identified a number of multivariate methods which can give a good evaluation of increased radon concentrations based on climate variables. The use of the multivariate regression methods will enable the investigation of the relations of specific climate variable with increased radon concentrations by analysis of regression methods resulting in 'mapped' underlying functional behaviour of radon concentrations depending on a wide spectrum of climate variables. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

LUNG INJURY AFTER OZONE EXPOSURE IS IRON-DEPENDENT

EPA Science Inventory

We tested the hypothesis that oxidative stress and biological effect after ozone (O3) exposure are dependent on changes in iron homeostasis. After O3 exposure, healthy volunteers demonstrated increased lavage concentrations of iron, transferrin, lactoferrin, and ferritin. In norm...

Absorption, distribution and excretion of inhaled hydrogen fluoride in the rat

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

Morris, J.B.

1979-01-01

Rats were subjected to whole body HF exposure for 6 hrs or to nose-only HF exposure for 1 hr. Total and/or ionic fluoride concentrations in selected tissues were determined at various times following exposure. In rats sacrificed 6 hrs after whole body exposure, dose-dependent increases in lung, plasma, and kidney total and ionic fluoride concentration occurred. Rats excreted more fluoride in the urine after whole body exposure than could be explained by the amount of HF inhaled. Considerable evidence suggests that airborne HF deposits on fur and is then ingested due to preening activity. Urinary fluoride excretion was increased bymore » nose-only exposure. The urinary fluoride excretion accounted for approximately twice the fluoride estimated to be inhaled during exposure. Tissue fluoride concentrations were elevated immediately after nose-only exposure. Fluoride concentrations in lung and kidney returned to control levels within 12 hrs. Plasma fluoride concentration was slightly elevated 24 hrs after the start of the 1 hr exposure but was at control levels at 96 hrs. Immediately following nose-only exposure, lung ionic fluoride concentrations were less than plasma ionic fluoride concentrations suggesting that the fluoride in the lung had reached that site via plasma transport rather than by inhalation. A dose-dependent increase in plasma ionic fluoride concentration occurred after upper respiratory tract HF exposure providing strong evidence that fluoride is absorbed systemically from that site. The plasma ionic fluoride concentration after upper respiratory tract exposure was of sufficient magnitude to account for the plasma fluoride concentrations observed in intact nose-only exposed rats. (ERB)« less

Pharmacologic characterization of the oxytocin receptor in human uterine smooth muscle cells.

PubMed

Tahara, A; Tsukada, J; Tomura, Y; Wada, K i; Kusayama, T; Ishii, N; Yatsu, T; Uchida, W; Tanaka, A

2000-01-01

[(3)H]-oxytocin was used to characterize the oxytocin receptor found in human uterine smooth muscle cells (USMC). Specific binding of [(3)H]-oxytocin to USMC plasma membranes was dependent upon time, temperature and membrane protein concentration. Scatchard plot analysis of equilibrium binding data revealed the existence of a single class of high-affinity binding sites with an apparent equilibrium dissociation constant (K(d)) of 0.76 nM and a maximum receptor density (B(max)) of 153 fmol mg(-1) protein. The Hill coefficient (n(H)) did not differ significantly from unity, suggesting binding to homogenous, non-interacting receptor populations. Competitive inhibition of [(3)H]-oxytocin binding showed that oxytocin and vasopressin (AVP) receptor agonists and antagonists displaced [(3)H]-oxytocin in a concentration-dependent manner. The order of potencies for peptide agonists and antagonists was: oxytocin>[Asu(1,6)]-oxytocin>AVP= atosiban>d(CH(2))(5)Tyr(Me)AVP>[Thr(4),Gly(7)]-oxytocin>dDAVP, and for nonpeptide antagonists was: L-371257>YM087>SR 49059>OPC-21268>SR 121463A>OPC-31260. Oxytocin significantly induced concentration-dependent increase in intracellular Ca(2+) concentration ([Ca(2+)](i)) and hyperplasia in USMC. The oxytocin receptor antagonists, atosiban and L-371257, potently and concentration-dependently inhibited oxytocin-induced [Ca(2+)](i) increase and hyperplasia. In contrast, the V(1A) receptor selective antagonist, SR 49059, and the V(2) receptor selective antagonist, SR 121463A, did not potently inhibit oxytocin-induced [Ca(2+)](i) increase and hyperplasia. The potency order of antagonists in inhibiting oxytocin-induced [Ca(2+)](i) increase and hyperplasia was similar to that observed in radioligand binding assays. In conclusion, these data provide evidence that the high-affinity [(3)H]-oxytocin binding site found in human USMC is a functional oxytocin receptor coupled to [Ca(2+)](i) increase and cell growth. Thus human USMC may prove to be a valuable tool in further investigation of the physiologic and pathophysiologic roles of oxytocin in the uterus. British Journal of Pharmacology (2000) 129, 131 - 139

Quantifying Main Trends in Lysozyme Nucleation: The Effect of Precipitant Concentration and Impurities

NASA Technical Reports Server (NTRS)

Burke, Michael W.; Judge, Russell A.; Pusey, Marc L.; Rose, M. Franklin (Technical Monitor)

2000-01-01

Full factorial experiment design incorporating multi-linear regression analysis of the experimental data allows the main trends and effects to be quickly identified while using only a limited number of experiments. These techniques were used to identify the effect of precipitant concentration and the presence of an impurity, the physiological lysozyme dimer, on the nucleation rate and crystal dimensions of the tetragonal form of chicken egg white lysozyme. Increasing precipitant concentration was found to decrease crystal numbers, the magnitude of this effect also depending on the supersaturation. The presence of the dimer generally increased nucleation. The crystal axial ratio decreased with increasing precipitant concentration independent of impurity.

On the Alloying and Properties of Tetragonal Nb5Si3 in Nb-Silicide Based Alloys

PubMed Central

Tsakiropoulos, Panos

2018-01-01

The alloying of Nb5Si3 modifies its properties. Actual compositions of (Nb,TM)5X3 silicides in developmental alloys, where X = Al + B + Ge + Si + Sn and TM is a transition and/or refractory metal, were used to calculate the composition weighted differences in electronegativity (Δχ) and an average valence electron concentration (VEC) and the solubility range of X to study the alloying and properties of the silicide. The calculations gave 4.11 < VEC < 4.45, 0.103 < Δχ < 0.415 and 33.6 < X < 41.6 at.%. In the silicide in Nb-24Ti-18Si-5Al-5Cr alloys with single addition of 5 at.% B, Ge, Hf, Mo, Sn and Ta, the solubility range of X decreased compared with the unalloyed Nb5Si3 or exceeded 40.5 at.% when B was with Hf or Mo or Sn and the Δχ decreased with increasing X. The Ge concentration increased with increasing Ti and the Hf concentration increased and decreased with increasing Ti or Nb respectively. The B and Sn concentrations respectively decreased and increased with increasing Ti and also depended on other additions in the silicide. The concentration of Sn was related to VEC and the concentrations of B and Ge were related to Δχ. The alloying of Nb5Si3 was demonstrated in Δχ versus VEC maps. Effects of alloying on the coefficient of thermal expansion (CTE) anisotropy, Young’s modulus, hardness and creep data were discussed. Compared with the hardness of binary Nb5Si3 (1360 HV), the hardness increased in silicides with Ge and dropped below 1360 HV when Al, B and Sn were present without Ge. The Al effect on hardness depended on other elements substituting Si. Sn reduced the hardness. Ti or Hf reduced the hardness more than Cr in Nb5Si3 without Ge. The (Nb,Hf)5(Si,Al)3 had the lowest hardness. VEC differentiated the effects of additions on the hardness of Nb5Si3 alloyed with Ge. Deterioration of the creep of alloyed Nb5Si3 was accompanied by decrease of VEC and increase or decrease of Δχ depending on alloying addition(s). PMID:29300327

Synergistic Effect of Transient Receptor Potential Antagonist and Amiloride against Maitotoxin Induced Calcium Increase and Cytotoxicity in Human Neuronal Stem Cells.

PubMed

Boente-Juncal, Andrea; Vale, Carmen; Alfonso, Amparo; Botana, Luis M

2018-05-16

Maitotoxins (MTX) are among the most potent marine toxins identified to date causing cell death trough massive calcium influx. However, the exact mechanism for the MTX-induced calcium entry and cytotoxicity is still unknown. In this work, the effect of MTX-1 on the cytosolic free calcium concentration and cellular viability of human neuronal stem cells was evaluated. MTX elicited a concentration-dependent decrease in cell viability which was already evident after 1 h of treatment with 0.25 nM MTX; however, at a concentration of 0.1 nM, the toxin did not cause cell death even after 14 days of exposure. Moreover, the toxin caused a concentration dependent rise in the cytosolic calcium concentration which was maximal at toxin concentrations of 1 nM and dependent on the presence of extracellular calcium on the bathing solution. Several pharmacological approaches were employed to evaluate the role of canonical transient potential receptor channels (TRPC) on the MTX effects. The results presented here lead to the identification of the TRPC4 channels as contributors to the MTX effects in human neuronal cells. Both, the calcium increase and the cytotoxicity of MTX were either fully (for the calcium increase) or partially (in the case of cytotoxicity) reverted by the blockade of canonical TRPC4 receptors with the selective antagonist ML204. Furthermore, the sodium proton exchanger blocker amiloride also partially inhibited the calcium rise and the cell death elicited by MTX while the combination of amiloride and ML204 fully prevented both the cytotoxicity and the calcium rise elicited by the toxin.

Functional coupling between sodium-activated potassium channels and voltage-dependent persistent sodium currents in cricket Kenyon cells.

PubMed

Takahashi, Izumi; Yoshino, Masami

2015-10-01

In this study, we examined the functional coupling between Na(+)-activated potassium (KNa) channels and Na(+) influx through voltage-dependent Na(+) channels in Kenyon cells isolated from the mushroom body of the cricket Gryllus bimaculatus. Single-channel activity of KNa channels was recorded with the cell-attached patch configuration. The open probability (Po) of KNa channels increased with increasing Na(+) concentration in a bath solution, whereas it decreased by the substitution of Na(+) with an equimolar concentration of Li(+). The Po of KNa channels was also found to be reduced by bath application of a high concentration of TTX (1 μM) and riluzole (100 μM), which inhibits both fast (INaf) and persistent (INaP) Na(+) currents, whereas it was unaffected by a low concentration of TTX (10 nM), which selectively blocks INaf. Bath application of Cd(2+) at a low concentration (50 μM), as an inhibitor of INaP, also decreased the Po of KNa channels. Conversely, bath application of the inorganic Ca(2+)-channel blockers Co(2+) and Ni(2+) at high concentrations (500 μM) had little effect on the Po of KNa channels, although Cd(2+) (500 μM) reduced the Po of KNa channels. Perforated whole cell clamp analysis further indicated the presence of sustained outward currents for which amplitude was dependent on the amount of Na(+) influx. Taken together, these results indicate that KNa channels could be activated by Na(+) influx passing through voltage-dependent persistent Na(+) channels. The functional significance of this coupling mechanism was discussed in relation to the membrane excitability of Kenyon cells and its possible role in the formation of long-term memory. Copyright © 2015 the American Physiological Society.

Self-organisation of semi-flexible rod-like particles

NASA Astrophysics Data System (ADS)

de Braaf, Bart; Oshima Menegon, Mariana; Paquay, Stefan; van der Schoot, Paul

2017-12-01

We report on a comprehensive computer simulation study of the liquid-crystal phase behaviour of purely repulsive, semi-flexible rod-like particles. For the four aspect ratios we consider, the particles form five distinct phases depending on their packing fraction and bending flexibility: the isotropic, nematic, smectic A, smectic B, and crystal phase. Upon increasing the particle bending flexibility, the various phase transitions shift to larger packing fractions. Increasing the aspect ratio achieves the opposite effect. We find two different ways in which the layer thickness of the particles in the smectic A phase may respond to an increase in concentration. The layer thickness may either decrease or increase depending on the aspect ratio and flexibility. For the smectic B and the crystalline phases, increasing the concentration always decreases the layer thickness. Finally, we find that the layer spacing jumps to a larger value on transitioning from the smectic A phase to the smectic B phase.

Intracellular calcium rise is not a necessary step for the stimulated actin polymerization

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

Yassin, R.

1986-03-01

Stimulation of rabbit peritoneal neutrophils by many chemotactic (formyl Methionyl-Leucyl-Phenylalanine (fMLP), Leukotriene B/sub 4/ (LTB/sub 4/)) and non-chemotactic (phorbol 12-myristate, 13-acetate (PMA), platelet activating factor (PAF), and the calcium ionophore A23187) factors produces rapid and dose dependent increases in the amount of actin associated with the cytoskeleton. The stimulated increase in cytoskeletal actin does not appear to require a rise in the intracellular concentration of free calcium. The increase in cytoskeletal actin produced by A23187 is transient and does not depend on the presence of calcium in the suspending medium. In the presence of extracellular calcium, the effect of themore » ionophore is biphasic with respect to concentration. The increases in actin association with cytoskeletal produced by fMLP, LTB/sub 4/, and A23187 but not by PMA, are inhibited by hyperosmolarity and pertussis toxin pretreatment. On the other hand, the addition of hyperosmolarity or pertussis toxin has small effect on the rise in the intracellular calcium produced by A23187. The results presented here suggest that an increase in the intracellular concentration of free calcium is not necessary for the stimulated increases in cytoskeletal actin.« less

Time-dependent efficiency measurements of polymer solar cells with dye additives: unexpected initial increase of efficiency

NASA Astrophysics Data System (ADS)

Bandaccari, Kyle J.; Chesmore, Grace E.; Bugaj, Mitchel; Valverde, Parisa Tajalli-Tehrani; Barber, Richard P.; McNelis, Brian J.

2018-04-01

We report the effects of the addition of two azo-dye additives on the time-dependent efficiency of polymer solar cells. Although the maximum efficiencies of devices containing different amounts of dye do not vary greatly over the selected concentration range, the time dependence results reveal a surprising initial increase in efficiency in some samples. We observe this effect to be correlated with a leakage current, although a specific mechanism is not yet identified. We also present the measured lifetimes of these solar cells, and find that variations in dye concentrations produce a small effect at most. Characterization of the bulk heterojunction layer (active layer) morphology using atomic-force microscope (AFM) imaging reveals reordering patterns which suggest that the primary effects of the dyes arise via structural, not absorptive, characteristics.

Structure, magnetization, and low-temperature impedance response of polycrystalline InSe intercalated with nickel

NASA Astrophysics Data System (ADS)

Stakhira, Y. M.; Tovstyuk, N. K.; Fomenko, V. L.; Grigorchak, I. I.; Borysyuk, A. K.; Seredyuk, B. A.

2012-01-01

A solid-phase mechanochemical technology of production of polycrystalline InSе intercalated with Ni up to 1.25 at. % has been developed. The x-ray and phase analyses of the produced NixInSe samples confirm their homogeneity and demonstrate a nonmonotonic Ni-content dependence of the lattice constant along the axis normal to the layers. Analysis of the low-temperature (77 K) impedance response within the frequency region 10-3-106 Hz shows a good correlation between the change in interlayer distance and in the band conductivity observed with increasing Ni concentration. However, the Ni concentration dependence of specific magnetization demonstrates an irregular increase at x ˜ 1 and does not coincide with the former. Such behavior is explained by the proposed theoretical model, which at the same time unveiled the mechanism behind the increasing contribution of free carrier concentration to conductivity - hybridization of electron orbitals of guest nickel and the lattice layers.

Influence of humic acid addition on the degradation of pharmaceuticals by biofilms in effluent wastewater.

PubMed

Tang, Kai; Escola Casas, Monica; Ooi, Gordon T H; Kaarsholm, Kamilla M S; Bester, Kai; Andersen, Henrik R

2017-05-01

The degradation of organic micropollutants in wastewater treatment is suspected to depend on co-degradation i.e. be dependent on concentrations of substrate. This complicates predicting and modelling their fate. The effect of humic acid, as a model for complex organic substrate, was investigated in relation to the biodegradation of pharmaceuticals by suspended biofilm carriers adapted to polishing effluent water from a tertiary sewage treatment plant. Twelve out of 22 investigated pharmaceuticals were significantly biodegradable. The biodegradation rate constants of ten of those compounds were increasing with increased humic acid concentrations. At the highest humic acid concentration (30mgC/L), the biodegradation rate constants were four times higher than the biodegradation rate constants without added humic acid. This shows that the presence of complex substrate stimulates degradation via a co-metabolism-like mechanism and competitive inhibition does not occur. Increases of rate constant per mgC/L are tentatively calculated. Copyright © 2017 Elsevier GmbH. All rights reserved.

Mn2+ concentration manipulated red emission in BaMg2Si2O7:Eu2+,Mn2+

NASA Astrophysics Data System (ADS)

Ye, Song; Zhang, Jiahua; Zhang, Xia; Lu, Shaozhe; Ren, Xinguang; Wang, Xiaojun

2007-02-01

The luminescent properties of concentration dependence are reported in BaMg2Si2O7:Eu2+,Mn2+ red phosphor. It is observed that the broad red emission of Mn2+ consists of two bands, located at 620 and 675 nm, respectively, which are attributed to two different Mn2+ centers [Mn2+(I) and Mn2+(II)] substituting for two nonidentical Mg2+ sites [Mg2+(I) and Mg2+(II)] in the host. It is also found that the relative emission intensity of the Mn2+(II) to the Mn2+(I) increases with increasing Mn2+ concentration, leading to a red-shift of the overall emission. A detail analysis on the energy transfer from Eu2+ to the two Mn2+ centers is presented, which indicates that the number ratio of Mn2+(II) to Mn2+(I) increases with increasing Mn2+ concentration. This result is interpreted by the preferential formation of Mn2+(I) substituting for Mg2+(I) site. Based on energy transfer, the emission intensity ratios of Mn2+(I) to Eu2+ and Mn2+(II) to Eu2+, which is Mn2+ concentration dependent, are calculated using related fluorescence lifetimes. The calculated results are in good agreement with that obtained experimentally in the emission spectra.

High-Intensity Locomotor Exercise Increases Brain-Derived Neurotrophic Factor in Individuals with Incomplete Spinal Cord Injury.

PubMed

Leech, Kristan A; Hornby, T George

2017-03-15

High-intensity locomotor exercise is suggested to contribute to improved recovery of locomotor function after neurological injury. This may be secondary to exercise-intensity-dependent increases in neurotrophin expression demonstrated previously in control subjects. However, rigorous examination of intensity-dependent changes in neurotrophin levels is lacking in individuals with motor incomplete spinal cord injury (SCI). Therefore, the primary aim of this study was to evaluate the effect of locomotor exercise intensity on peripheral levels of brain-derived neurotrophic factor (BDNF) in individuals with incomplete SCI. We also explored the impact of the Val66Met single-nucleotide polymorphism (SNP) on the BDNF gene on intensity-dependent changes. Serum concentrations of BDNF and insulin-like growth factor-1 (IGF-1), as well as measures of cardiorespiratory dynamics, were evaluated across different levels of exercise intensity achieved during a graded-intensity, locomotor exercise paradigm in 11 individuals with incomplete SCI. Our results demonstrate a significant increase in serum BDNF at high, as compared to moderate, exercise intensities (p = 0.01) and 15 and 30 min post-exercise (p < 0.01 for both), with comparison to changes at low intensity approaching significance (p = 0.05). Serum IGF-1 demonstrated no intensity-dependent changes. Significant correlations were observed between changes in BDNF and specific indicators of exercise intensity (e.g., rating of perceived exertion; R = 0.43; p = 0.02). Additionally, the data suggest that Val66Met SNP carriers may not exhibit intensity-dependent changes in serum BDNF concentration. Given the known role of BDNF in experience-dependent neuroplasticity, these preliminary results suggest that exercise intensity modulates serum BDNF concentrations and may be an important parameter of physical rehabilitation interventions after neurological injury.

High-Intensity Locomotor Exercise Increases Brain-Derived Neurotrophic Factor in Individuals with Incomplete Spinal Cord Injury

PubMed Central

Leech, Kristan A.

2017-01-01

Abstract High-intensity locomotor exercise is suggested to contribute to improved recovery of locomotor function after neurological injury. This may be secondary to exercise-intensity–dependent increases in neurotrophin expression demonstrated previously in control subjects. However, rigorous examination of intensity-dependent changes in neurotrophin levels is lacking in individuals with motor incomplete spinal cord injury (SCI). Therefore, the primary aim of this study was to evaluate the effect of locomotor exercise intensity on peripheral levels of brain-derived neurotrophic factor (BDNF) in individuals with incomplete SCI. We also explored the impact of the Val66Met single-nucleotide polymorphism (SNP) on the BDNF gene on intensity-dependent changes. Serum concentrations of BDNF and insulin-like growth factor-1 (IGF-1), as well as measures of cardiorespiratory dynamics, were evaluated across different levels of exercise intensity achieved during a graded-intensity, locomotor exercise paradigm in 11 individuals with incomplete SCI. Our results demonstrate a significant increase in serum BDNF at high, as compared to moderate, exercise intensities (p = 0.01) and 15 and 30 min post-exercise (p < 0.01 for both), with comparison to changes at low intensity approaching significance (p = 0.05). Serum IGF-1 demonstrated no intensity-dependent changes. Significant correlations were observed between changes in BDNF and specific indicators of exercise intensity (e.g., rating of perceived exertion; R = 0.43; p = 0.02). Additionally, the data suggest that Val66Met SNP carriers may not exhibit intensity-dependent changes in serum BDNF concentration. Given the known role of BDNF in experience-dependent neuroplasticity, these preliminary results suggest that exercise intensity modulates serum BDNF concentrations and may be an important parameter of physical rehabilitation interventions after neurological injury. PMID:27526567

Associations between butane hash oil use and cannabis-related problems.

PubMed

Meier, Madeline H

2017-10-01

High-potency cannabis concentrates are increasingly popular in the United States, and there is concern that use of high-potency cannabis might increase risk for cannabis-related problems. However, little is known about the potential negative consequences of concentrate use. This study reports on associations between past-year use of a high-potency cannabis concentrate, known as butane hash oil (BHO), and cannabis-related problems. A sample of 821 college students were recruited to complete a survey about their health and behavior. Participants who had used cannabis in the past year (33%, n=273) completed questions about their cannabis use, including their use of BHO and cannabis-related problems in eight domains: physical dependence, impaired control, academic-occupational problems, social-interpersonal problems, self-care problems, self-perception, risk behavior, and blackouts. Approximately 44% (n=121) of past-year cannabis users had used BHO in the past year. More frequent BHO use was associated with higher levels of physical dependence (RR=1.8, p<0.001), impaired control (RR=1.3, p<0.001), cannabis-related academic/occupational problems (RR=1.5, p=0.004), poor self-care (RR=1.3, p=0.002), and cannabis-related risk behavior (RR=1.2, p=0.001). After accounting for sociodemographic factors, age of onset of cannabis use, sensation seeking, overall frequency of cannabis use, and frequency of other substance use, BHO use was still associated with higher levels of physical dependence (RR=1.2, p=0.014). BHO use is associated with greater physiological dependence on cannabis, even after accounting for potential confounders. Longitudinal research is needed to determine if cannabis users with higher levels of physiological dependence seek out BHO and/or if BHO use increases risk for physiological dependence. Copyright © 2017 Elsevier B.V. All rights reserved.

Contaminant transport in soil with depth-dependent reaction coefficients and time-dependent boundary conditions.

PubMed

Gao, Guangyao; Fu, Bojie; Zhan, Hongbin; Ma, Ying

2013-05-01

Predicting the fate and movement of contaminant in soils and groundwater is essential to assess and reduce the risk of soil contamination and groundwater pollution. Reaction processes of contaminant often decreased monotonously with depth. Time-dependent input sources usually occurred at the inlet of natural or human-made system such as radioactive waste disposal site. This study presented a one-dimensional convection-dispersion equation (CDE) for contaminant transport in soils with depth-dependent reaction coefficients and time-dependent inlet boundary conditions, and derived its analytical solution. The adsorption coefficient and degradation rate were represented as sigmoidal functions of soil depth. Solute breakthrough curves (BTCs) and concentration profiles obtained from CDE with depth-dependent and constant reaction coefficients were compared, and a constant effective reaction coefficient, which was calculated by arithmetically averaging the depth-dependent reaction coefficient, was proposed to reflect the lumped depth-dependent reaction effect. With the effective adsorption coefficient and degradation rate, CDE could produce similar BTCs and concentration profiles as those from CDE with depth-dependent reactions in soils with moderate chemical heterogeneity. In contrast, the predicted concentrations of CDE with fitted reaction coefficients at a certain depth departed significantly from those of CDE with depth-dependent reactions. Parametric analysis was performed to illustrate the effects of sinusoidally and exponentially decaying input functions on solute BTCs. The BTCs and concentration profiles obtained from the solutions for finite and semi-infinite domain were compared to investigate the effects of effluent boundary condition. The finite solution produced higher concentrations at the increasing limb of the BTCs and possessed a higher peak concentration than the semi-infinite solution which had a slightly long tail. Furthermore, the finite solution gave a higher concentration in the immediate vicinity of the exit boundary than the semi-infinite solution. The applicability of the proposed model was tested with a field herbicide and tracer leaching experiment in an agricultural area of northeastern Greece. The simulation results indicated that the proposed CDE with depth-dependent reaction coefficients was able to capture the evolution of metolachlor concentration at the upper soil depths. However, the simulation results at deep depths were not satisfactory as the proposed model did not account for preferential flow observed in the field. Copyright © 2013 Elsevier Ltd. All rights reserved.

Acidic pH increases airway surface liquid viscosity in cystic fibrosis

PubMed Central

Tang, Xiao Xiao; Ostedgaard, Lynda S.; Hoegger, Mark J.; Moninger, Thomas O.; Karp, Philip H.; McMenimen, James D.; Choudhury, Biswa; Varki, Ajit; Stoltz, David A.; Welsh, Michael J.

2016-01-01

Cystic fibrosis (CF) disrupts respiratory host defenses, allowing bacterial infection, inflammation, and mucus accumulation to progressively destroy the lungs. Our previous studies revealed that mucus with abnormal behavior impaired mucociliary transport in newborn CF piglets prior to the onset of secondary manifestations. To further investigate mucus abnormalities, here we studied airway surface liquid (ASL) collected from newborn piglets and ASL on cultured airway epithelia. Fluorescence recovery after photobleaching revealed that the viscosity of CF ASL was increased relative to that of non-CF ASL. CF ASL had a reduced pH, which was necessary and sufficient for genotype-dependent viscosity differences. The increased viscosity of CF ASL was not explained by pH-independent changes in HCO3– concentration, altered glycosylation, additional pH-induced disulfide bond formation, increased percentage of nonvolatile material, or increased sulfation. Treating acidic ASL with hypertonic saline or heparin largely reversed the increased viscosity, suggesting that acidic pH influences mucin electrostatic interactions. These findings link loss of cystic fibrosis transmembrane conductance regulator–dependent alkalinization to abnormal CF ASL. In addition, we found that increasing Ca2+ concentrations elevated ASL viscosity, in part, independently of pH. The results suggest that increasing pH, reducing Ca2+ concentration, and/or altering electrostatic interactions in ASL might benefit early CF. PMID:26808501

Nitric oxide mediates brassinosteroid-induced flavonoid biosynthesis in Camellia sinensis L.

PubMed

Li, Xin; Zhang, Lan; Ahammed, Golam Jalal; Li, Zhi-Xin; Wei, Ji-Peng; Shen, Chen; Yan, Peng; Zhang, Li-Ping; Han, Wen-Yan

2017-07-01

Flavonoids are one of the key secondary metabolites determining the quality of tea. Although exogenous brassinosteroid (BR), a steroidal plant hormone, can stimulate polyphenol biosynthesis in tea plants (Camellia sinensis L.), the relevance of endogenous BR in flavonoid accumulation and the underlying mechanisms remain largely unknown. Here we show that BR enhances flavonoid concentration in tea leaves by inducing an increase in the endogenous concentration of nitric oxide (NO). Notably, exogenous BR increased levels of flavonoids as well as NO in a concentration dependent manner, while suppression of BR levels by an inhibitor of BR biosynthesis, brassinazole (BRz), decreased the concentrations of both flavonoids and NO in tea leaves. Interestingly, combined treatment of BR and BRz reversed the inhibitory effect of BRz alone on the concentrations of flavonoids and NO. Likewise, exogenous NO also increased flavonoids and NO levels dose-dependently. When the NO level in tea leaves was suppressed by using a NO scavenger, 2,4-carboxyphenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO), flavonoid concentration dramatically decreased. Although individual application of 0.1μM BR increased the concentrations of flavonoids and NO, combined treatment with exogenous NO scavenger, cPTIO, reversed the effect of BR on flavonoid concentration. Furthermore, BR or sodium nitroprusside (SNP) promoted but cPTIO inhibited the transcription and activity of phenylalanine ammonia-lyase (PAL) in leaves, while combined treatment of BR with SNP or cPTIO had no additive effect. The results of this study suggest that an optimal level of endogenous NO is essential for BR-induced promotion of flavonoid biosynthesis in tea leaves. In conclusion, this study unveiled a crucial mechanism of BR-induced flavonoid biosynthesis, which might have potential implication in improving the quality of tea. Copyright © 2017 Elsevier GmbH. All rights reserved.

New understanding and quantification of the regime dependence of aerosol-cloud interaction for studying aerosol indirect effects

DOE PAGES

Chen, Jingyi; Liu, Yangang; Zhang, Minghua; ...

2016-02-28

In this study, aerosol indirect effects suffer from large uncertainty in climate models and among observations. This study focuses on two plausible factors: regime dependence of aerosol-cloud interactions and the effect of cloud droplet spectral shape. We show, using a new parcel model, that combined consideration of droplet number concentration (N c) and relative dispersion (ε, ratio of standard deviation to mean radius of the cloud droplet size distribution) better characterizes the regime dependence of aerosol-cloud interactions than considering N c alone. Given updraft velocity (w), ε increases with increasing aerosol number concentration (N a) in the aerosol-limited regime, peaksmore » in the transitional regime, and decreases with further increasing N a in the updraft-limited regime. This new finding further reconciles contrasting observations in literature and reinforces the compensating role of dispersion effect. The nonmonotonic behavior of ε further quantifies the relationship between the transitional N a and w that separates the aerosol- and updraft-limited regimes.« less

Label-free electrochemical detection of botulinum neurotoxin type E based on its enzymatic activity using interdigitated electrodes

NASA Astrophysics Data System (ADS)

Hyun, Sang Hwa; Park, Dae Keun; Kang, Aeyeon; Kim, Soohyun; Kim, Daehee; Shin, Yu Mi; Song, Ji-Joon; Yun, Wan Soo

2016-02-01

We report a simple label-free electrochemical method of detecting low concentrations of botulinum neurotoxin type E light chain (BoNT/E LC) based on its peptide cleavage activity. Dual-mode cyclic voltammetry was employed to observe changes in the redox signal of ferri-/ferro-cyanide on interdigitated microelectrodes, whose surfaces were covered by peptides designed from synaptosomal-associated protein 25 to be cleaved by BoNT/E LC. With the introduction of BoNT/E LC, the redox signal showed a time-dependent increase due to cleavage of the immobilized peptide molecules. In addition to the increased redox signal intensity, its time-dependence can be considered as a strong evidence of BoNT/E sensing, since the time-dependent increase can only result from the enzymatic activity of BoNT/E LC. Using this method, BoNT/E LC, at concentrations as low as 5 pg/ml, was readily measurable with only an hour of incubation.

CO2 convective dissolution controlled by temporal changes in free-phase CO2 properties

NASA Astrophysics Data System (ADS)

Jafari Raad, S. M.; Emami-Meybodi, H.; Hassanzadeh, H.

2017-12-01

Understanding the factors that control CO2 convective dissolution, which is one of the permanent trapping mechanisms, in the deep saline aquifer is crucial in the long-term fate of the injected CO2. The present study investigates the effects of temporal changes in the solubility of CO2 at the free-phase CO2/brine interface on the onset of natural convection and the subsequent convective mixing by conducting linear stability analyses (LSA) and direct numerical simulations (DNS). A time-dependent concentration boundary is considered for the free-phase CO2/brine interface where the CO2 concentration first decreases with the time and then remains constant. The LSA results show that the temporal variation in the concentration increases the onset of natural convection up to two orders of magnitude. In addition, the critical Rayleigh number significantly increases as CO2 concentration decreases. In other words, size and pressure of the injected CO2 affect the commencement of convective mixing. Based on LSA results, several scaling relations are proposed to correlate critical Rayleigh number, critical time, and its corresponding wavenumbers with time-dependent boundary's parameters, such as concentration decline rate and equilibrium concentration ratio. The DNS results reveal that the convective fingering patterns are significantly influenced by the variation of CO2 concentration at the interface. These findings improve our understanding of CO2 solubility trapping and are particularly important in estimation of potential storage capacity, risk assessment, and storage sites characterization and screening. Keywords: CO2 sequestration; natural convection; solubility trapping; time-dependent boundary condition; numerical simulation; stability analysis

Photoluminescence properties of polystyrene-hosted fluorophore thin films

NASA Astrophysics Data System (ADS)

Chakraborty, Subha; Harris, Katherine; Huang, Mengbing

2016-12-01

We report on a photo-luminescence study of four different fluorophores: Coumarin 6, 2,5-Diphenyloxazole (PPO), 1,4-Bis(5-phenyl-2-oxazolyl)benzene (POPOP) and Para-terpehnyl (PTP), doped in a polystyrene-based thin film. All of the samples are prepared by spin coating from a non-polar polymer solution at various concentrations. Their emission spectra and transient properties are characterized by photoluminescence measurements. Red-shifts in the emission spectra are observed for all four types of fluorophores as their concentration increases. We explain this phenomenon based on concentration dependence of solvatochromic effects and the results show good agreement with existing literature. We also show that the singlet-singlet annihilation processes are possibly a prevalent mechanism in the high concentration regime that affects the steady state and transient emission characteristics of the fluors. With the exception of PTP, photoluminescence quenching occurs as the fluorophore concentration in the polymer is increased. Rate equations for excited state decay mechanisms are analysed by considering different radiative and non-radiative energy transfer mechanisms. The results show consistency with our experimental observations. PTP shows the best photoluminescence results as an efficient fluor in the thin film, whereas PPO shows the strongest concentration dependent quenching and an anomalous lifetime distribution.

Application of DBS sampling in combination with LC-MS/MS for pharmacokinetic evaluation of a compound with species-specific blood-to-plasma partitioning.

PubMed

Xu, Guifen; Chen, Jiyun S; Phadnis, Ruta; Huang, Tom; Uyeda, Craig; Soto, Marcus; Stouch, Brian; Wells, Mary C; James, Christopher A; Carlson, Timothy J

2012-08-01

Dried blood spot (DBS) sampling in combination with LC-MS/MS has been used increasingly in drug discovery for quantitative analysis to support pharmacokinetic (PK) studies. In this study, we assessed the effect of blood-to-plasma (B:P) partitioning on the bioanalytical performance and PK data acquired by DBS for a compound AMG-1 with species and concentration-dependent B:P ratio. B:P partitioning did not adversely affect bioanalytical performance of DBS for AMG-1. For rat, (B:P ratio of 0.63), PK profiles from DBS and plasma methods were comparable. For dog, concentration-dependence of B:P ratio was observed both in vivo and in vitro. Additional studies demonstrated concentration-dependence of the compound's unbound fraction in plasma, which may contribute to the concentration-dependence of the B:P ratio. DBS is a promising sampling technique for preclinical pharmacokinetic studies. For compounds with high B:P ratio, caution needs to be applied for data comparison and interpretation between matrices.

A comparative sonochemical reaction that is independent of the intensity of ultrasound and the geometry of the exposure apparatus.

PubMed

Sostaric, Joe Z

2008-09-01

Sonolysis of aqueous solutions of n-alkyl anionic surfactants results in the formation of secondary carbon-centered radicals (-*CH-). The yield of -*CH- depends on the bulk surfactant concentration up to a maximum attainable radical yield (the 'plateau yield') where an increasing surfactant concentration (below the critical micelle concentration) no longer affects the -*CH- yield. In an earlier study it was found that the ratio of -*CH- detected following sonolysis of aqueous solutions of sodium pentane sulfonate (SPSo) to that of sodium dodecyl sulfate (SDS) (i.e. CH(SPSo)/CH(SDS)) depended on the frequency of sonolysis, but was independent of the ultrasound intensity, at the plateau concentrations [J.Z. Sostaric, P. Riesz, Adsorption of surfactants at the gas/solution interface of cavitation bubbles: an ultrasound intensity-independent frequency effect in sonochemistry, J. Phys. Chem. B 106 (2002) 12537-12548]. In the current study, it was found that the CH(SPSo)/CH(SDS) ratio depended only on the ultrasound frequency and did not depend on the geometry of the ultrasound exposure apparatus considered.

Inflammaging and Frailty Status Do Not Result in an Increased Extracellular Vesicle Concentration in Circulation

PubMed Central

Alberro, Ainhoa; Sáenz-Cuesta, Matías; Muñoz-Culla, Maider; Mateo-Abad, Maider; Gonzalez, Esperanza; Carrasco-Garcia, Estefania; Araúzo-Bravo, Marcos J.; Matheu, Ander; Vergara, Itziar; Otaegui, David

2016-01-01

In the last decades extracellular vesicles (EVs) have emerged as key players for intercellular communication. In the case of inflammation, several studies have reported that EV levels are increased in circulation during inflammatory episodes. Based on this, we investigated whether aging results in elevated EV number, as a basal proinflammatory status termed “inflammaging” has been described in aged individuals. Moreover, we also hypothesized that frailty and dependence conditions of the elderly could affect EV concentration in plasma. Results showed that inflammaging, frailty or dependence status do not result in EV increase, at least in the total number of EVs in circulation. These results open a new perspective for investigating the role of EVs in human aging and in the inflammaging process. PMID:27447627

Inflammaging and Frailty Status Do Not Result in an Increased Extracellular Vesicle Concentration in Circulation.

PubMed

Alberro, Ainhoa; Sáenz-Cuesta, Matías; Muñoz-Culla, Maider; Mateo-Abad, Maider; Gonzalez, Esperanza; Carrasco-Garcia, Estefania; Araúzo-Bravo, Marcos J; Matheu, Ander; Vergara, Itziar; Otaegui, David

2016-07-20

In the last decades extracellular vesicles (EVs) have emerged as key players for intercellular communication. In the case of inflammation, several studies have reported that EV levels are increased in circulation during inflammatory episodes. Based on this, we investigated whether aging results in elevated EV number, as a basal proinflammatory status termed "inflammaging" has been described in aged individuals. Moreover, we also hypothesized that frailty and dependence conditions of the elderly could affect EV concentration in plasma. Results showed that inflammaging, frailty or dependence status do not result in EV increase, at least in the total number of EVs in circulation. These results open a new perspective for investigating the role of EVs in human aging and in the inflammaging process.

Power law relation between particle concentrations and their sizes in the blood plasma

NASA Astrophysics Data System (ADS)

Kirichenko, M. N.; Chaikov, L. L.; Zaritskii, A. R.

2016-08-01

This work is devoted to the investigation of sizes and concentrations of particles in blood plasma by dynamic light scattering (DLS). Blood plasma contains many different proteins and their aggregates, microparticles and vesicles. Their sizes, concentrations and shapes can give information about donor's health. Our DLS study of blood plasma reveals unexpected dependence: with increasing of the particle sizes r (from 1 nm up to 1 μm), their concentrations decrease as r-4 (almost by 12 orders). We found also that such dependence was repeated for model solution of fibrinogen and thrombin with power coefficient is -3,6. We believe that this relation is a fundamental law of nature that shows interaction of proteins (and other substances) in biological liquids.

Detection on emamectin benzoate-induced apoptosis and DNA damage in Spodoptera frugiperda Sf-9 cell line.

PubMed

Wu, Xiwei; Zhang, Lei; Yang, Chao; Zong, Mimi; Huang, Qingchun; Tao, Liming

2016-01-01

Emamectin benzoate (EMB), an important macrocyclic lactone insecticide that belongs to the avermectin family and possesses excellent potency in controlling pests, is non-carcinogenic and non-mutagenic conducted in rats and mice, but EMB-induced cytotoxicity and genotoxicity in arthropod insect have been seldom reported yet. In the present paper, we quantified the cytotoxicity of EMB through the detections on cell viability, DNA damage, and cell apoptosis in Spodoptera frugiperda Sf-9 cells in vitro. The results showed that EMB caused a concentration- and time-dependent reduction on the viability of Sf-9 cells, and the median inhibitory concentrations (IC50) were 3.34μM at 72h of exposure. The dual acridine orange/ethidium bromide staining showed that exposure to EMB induced a significant time- and concentration-dependent increase on cell apoptosis. The alkaline comet assay revealed that EMB induced significant increases on single-strand DNA breaks, and the percentage of γH2AX-positive cells represented a time- and concentration-dependent formation of DNA double-strand breaks in Sf-9 cells. Interestingly, the similar cytotoxic actions of EMB also went for the human cancerous HeLa cells as a control cell group. Data demonstrated the potential cytotoxic effect of EMB on Sf-9 cells that was significantly greater than the effect of hydrogen peroxide at the same concentrations. Copyright © 2015 Elsevier Inc. All rights reserved.

Dietary selenomethionine increases exon-specific DNA methylation of the p53 gene in rat liver and colon mucosa.

PubMed

Zeng, Huawei; Yan, Lin; Cheng, Wen-Hsing; Uthus, Eric O

2011-08-01

The regulation of site-specific DNA methylation of tumor suppressor genes has been considered as a leading mechanism by which certain nutrients exert their anticancer property. This study was to investigate whether selenium (Se) affects the methylation of globe genomic DNA and the exon-specific p53 gene. Three groups of rats (n = 6-7/group) were fed the AIN-93G basal diet supplemented with 0 [Se deficient (D)], 0.15 [Se adequate (A)], or 4 mg [Se supranutritional (S)] (Se as l-selenomethionine)/kg diet for 104 d, respectively. Rats fed the A or S diet had greater plasma and liver glutathione peroxidase activity, liver thioredoxin reductase activity, and plasma homocysteine concentration than those fed the D diet. However, compared with the A diet, rats fed the S diet did not further increase these Se-dependent enzyme activities or homocysteine concentration. In contrast, Se concentrations in kidney, liver, gastrocnemius muscle, and plasma were increased in a Se-dose-dependent manner. Interestingly, rats fed the S diet had significantly less global liver genomic DNA methylation than those fed the D diet. However, the S diet significantly increased the methylation of the p53 gene (exons 5-8) but not the β-actin gene (exons 2-3) DNA in liver and colon mucosa compared with those fed the D diet. Taken together, long-term Se consumption not only affects selenoprotein enzyme activities, homocysteine, tissue Se concentrations, and global genomic DNA methylation but also increases exon-specific DNA methylation of the p53 gene in a Se-dose-dependent manner in rat liver and colon mucosa.

Quantification of Kinetic Rate Law Parameters of Uranium Release from Sodium Autunite as a Function of Aqueous Bicarbonate Concentrations

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

Gudavalli, Ravi; Katsenovich, Yelena; Wellman, Dawn M.

2013-09-05

ABSTRACT: Hydrogen carbonate is one of the most significant components within the uranium geochemical cycle. In aqueous solutions, hydrogen carbonate forms strong complexes with uranium. As such, aqueous bicarbonate may significantly increase the rate of uranium release from uranium minerals. Quantifying the relationship of aqueous hydrogen carbonate solutions to the rate of uranium release during dissolution is critical to understanding the long-term fate of uranium within the environment. Single-pass flow-through (SPTF) experiments were conducted to estimate the rate of uranium release from Na meta-autunite as a function of bicarbonate solutions (0.0005-0.003 M) under the pH range of 6-11 and temperaturesmore » of 5-60oC. Consistent with the results of previous investigation, the rate of uranium release from sodium autunite exhibited minimal dependency on temperature; but were strongly dependent on pH and increasing concentrations of bicarbonate solutions. Most notably at pH 7, the rate of uranium release exhibited 370 fold increases relative to the rate of uranium release in the absence of bicarbonate. However, the effect of increasing concentrations of bicarbonate solutions on the release of uranium was significantly less under higher pH conditions. It is postulated that at high pH values, surface sites are saturated with carbonate, thus the addition of more bicarbonate would have less effect on uranium release. Results indicate the activation energies were unaffected by temperature and bicarbonate concentration variations, but were strongly dependent on pH conditions. As pH increased from 6 to 11, activation energy values were observed to decrease from 29.94 kJ mol-1 to 13.07 kJ mol-1. The calculated activation energies suggest a surface controlled dissolution mechanism.« less

Genotoxicity of two heavy metal compounds: lead nitrate and cobalt chloride in Polychaete Perinereis cultrifera.

PubMed

Singh, Nisha; Bhagat, Jacky; Ingole, Baban S

2017-07-01

The present study explores the in vivo and in vitro genotoxic effects of lead nitrate, [Pb(NO 3 ) 2 ] a recognized environmental pollutant and cobalt chloride (CoCl 2 ), an emerging environmental pollutant in polychaete Perinereis cultrifera using comet assay. Despite widespread occurrence and extensive industrial applications, no previous published reports on genotoxicity of these compounds are available in polychaete as detected by comet assay. Polychaetes were exposed in vivo to Pb(NO 3 ) 2 (0, 100, 500, and 1000 μg/l) and CoCl 2 (0, 100, 300, and 500 μg/l) for 5 days. At 100 μg/l Pb(NO 3 ) 2 concentration, tail DNA (TDNA) values in coelomocytes were increase by 1.16, 1.43, and 1.55-fold after day 1, day 3, and day 5, whereas, OTM showed 1.12, 2.33, and 2.10-fold increase in in vivo. Pb(NO 3 ) 2 showed a concentration and time-dependent genotoxicity whereas CoCl 2 showed a concentration-dependent genotoxicity in in vivo. A concentration-dependent increase in DNA damage was observed in in vitro studies for Pb(NO 3 ) 2 and CoCl 2 . DNA damage at 500 μg/L showed almost threefold increase in TDNA and approximately fourfold increase in OTM as compared to control in in vitro. Our studies suggest that Pb(NO 3 ) 2 and CoCl 2 have potential to cause genotoxic damage, with Pb(NO 3 ) 2 being more genotoxic in polychaete and should be used more carefully in industrial and other activities. Graphical abstract.

Tunable Assembly of Gold Nanorods in Polymer Solutions To Generate Controlled Nanostructured Materials

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

Poling-Skutvik, Ryan; Lee, Jonghun; Narayanan, Suresh

In this study, gold nanorods grafted with short chain polymers are assembled into controlled open structures using polymer-induced depletion interactions and structurally characterized using small angle x-ray scattering. When the nanorod diameter is smaller than the radius of gyration of the depletant polymer, the depletion interaction depends solely on the correlation length of the polymer solution and not directly on the polymer molecular weight. As the polymer concentration increases, the stronger depletion interactions increasingly compress the grafted chains and push the gold nanorods closer together. By contrast, other structural characteristics such as the number of nearest neighbors and fractal dimensionmore » exhibit a non-monotonic dependence on polymer concentration. These parameters are maximal at intermediate concentrations, which are attributed to a crossover from reaction-limited to diffusion-limited aggregation. Finally, the control over structural properties of anisotropic nanoscale building blocks demonstrated here will be beneficial to designing and producing materials in situ with specific direction-dependent nanoscale properties and provides a crucial route for advances in additive manufacturing.« less

Tunable Assembly of Gold Nanorods in Polymer Solutions To Generate Controlled Nanostructured Materials

DOE PAGES

Poling-Skutvik, Ryan; Lee, Jonghun; Narayanan, Suresh; ...

2018-01-17

In this study, gold nanorods grafted with short chain polymers are assembled into controlled open structures using polymer-induced depletion interactions and structurally characterized using small angle x-ray scattering. When the nanorod diameter is smaller than the radius of gyration of the depletant polymer, the depletion interaction depends solely on the correlation length of the polymer solution and not directly on the polymer molecular weight. As the polymer concentration increases, the stronger depletion interactions increasingly compress the grafted chains and push the gold nanorods closer together. By contrast, other structural characteristics such as the number of nearest neighbors and fractal dimensionmore » exhibit a non-monotonic dependence on polymer concentration. These parameters are maximal at intermediate concentrations, which are attributed to a crossover from reaction-limited to diffusion-limited aggregation. Finally, the control over structural properties of anisotropic nanoscale building blocks demonstrated here will be beneficial to designing and producing materials in situ with specific direction-dependent nanoscale properties and provides a crucial route for advances in additive manufacturing.« less

Pesticide-contaminated feeds in integrated grass carp aquaculture: toxicology and bioaccumulation.

PubMed

Pucher, J; Gut, T; Mayrhofer, R; El-Matbouli, M; Viet, P H; Ngoc, N T; Lamers, M; Streck, T; Focken, U

2014-02-19

Effects of dissolved pesticides on fish are widely described, but little is known about effects of pesticide-contaminated feeds taken up orally by fish. In integrated farms, pesticides used on crops may affect grass carp that feed on plants from these fields. In northern Vietnam, grass carp suffer seasonal mass mortalities which may be caused by pesticide-contaminated plants. To test effects of pesticide-contaminated feeds on health and bioaccumulation in grass carp, a net-cage trial was conducted with 5 differently contaminated grasses. Grass was spiked with 2 levels of trichlorfon/fenitrothion and fenobucarb. Unspiked grass was used as a control. Fish were fed at a daily rate of 20% of body mass for 10 d. The concentrations of fenitrothion and fenobucarb in pond water increased over time. Effects on fish mortality were not found. Fenobucarb in feed showed the strongest effects on fish by lowering feed uptake, deforming the liver, increasing blood glucose and reducing cholinesterase activity in blood serum, depending on feed uptake. Fenobucarb showed increased levels in flesh in all treatments, suggesting bio-concentration. Trichlorfon and fenitrothion did not significantly affect feed uptake but showed concentration-dependent reduction of cholinesterase activity and liver changes. Fenitrothion showed bioaccumulation in flesh which was dependant on feed uptake, whereas trichlorfon was only detected in very low concentrations in all treatments. Pesticide levels were all detected below the maximum residue levels in food. The pesticide-contaminated feeds tested did not cause mortality in grass carp but were associated with negative physiological responses and may increase susceptibility to diseases.

Liquid ``Coffee Rings'' and the Spreading of Volatile Liquid Mixtures

NASA Astrophysics Data System (ADS)

Wood, Clay; Pye, Justin; Burton, Justin

When a volatile liquid drop is placed on a wetting surface, it rapidly spreads and evaporates. The spreading dynamics and drop geometry are determined by a balance between thermal and interfacial forces, including Marangoni effects. However, this spreading behavior is drastically altered when drops contain a miniscule amount of a less-volatile miscible liquid (solute) in the bulk (solvent); contact line instabilities in the form of ``fingers'' develop. Characteristic finger size increases with increasing solute concentration and is apparent for concentrations as small as 0.1% by volume. Also, the spreading rate depends sensitively on the solute concentration, especially if the solute preferentially wets the substrate. At higher solute concentrations, the spreading droplet will form ``beads'' at the contact line, rather than fingers, and are deposited as the solvent recedes and evaporates, leaving behind a complex pattern of solute micro-droplets. Liquid ``coffee rings'' are often left behind after evaporation because there is a high evaporation rate of the solvent at the contact line, which increases the concentration of the solute, and the longevity of the rings depends on the solute vapor pressure. These results highlight the unusual sensitivity to contamination of volatile spreading, and the complex patterns of liquid contamination deposited following evaporation from a wetted surface. NSF 1455086.

Evidence for a hyperglycaemia-dependent decrease of antithrombin III-thrombin complex formation in humans.

PubMed

Ceriello, A; Giugliano, D; Quatraro, A; Marchi, E; Barbanti, M; Lefèbvre, P

1990-03-01

In the presence of increased levels of fibrinopeptide A, decreased antithrombin III biological activity, and thrombin-antithrombin III complex levels are seen in diabetic patients. Induced-hyperglycaemia in diabetic and normal subjects decreased antithrombin III activity and thrombin-antithrombin III levels, and increased fibrinopeptide A plasma levels, while antithrombin III concentration did not change; heparin was shown to reduced these phenomena. In diabetic patients, euglycaemia induced by insulin infusion restored antithrombin III activity, thrombin-antithrombin III complex and fibrinopeptide A concentrations; heparin administration had the same effects. These data stress the role of a hyperglycaemia-dependent decrease of antithrombin III activity in precipitating thrombin hyperactivity in diabetes mellitus.

Composition-dependent damping and relaxation dynamics in miscible polymer blends above glass transition temperature by anelastic spectroscopy

NASA Astrophysics Data System (ADS)

Wu, Xuebang; Shang, Shuying; Xu, Qiaoling; Liu, Changsong; Zhu, Zhengang; Zhang, Guangzhao

2008-07-01

Anelastic spectroscopy is used to study the composition dependence of the damping and molecular relaxation dynamics in miscible poly(ethylene oxide) (PEO)/poly(methyl methacrylate) (PMMA) blends above the glass transition temperature. The ultrahigh damping peak of the relaxation type is shown to be associated with the liquid-liquid transition of PMMA. A higher PEO concentration leads to a higher damping performance and a lower transition temperature. The decreasing activation energy with increasing PEO concentration indicates a drastic increase in molecular mobility. Moreover, the relaxation time reveals a transition from the Vogel-Fulcher-Tamman behavior to the Arrhenius behavior due to the intermolecular guest-host interactions.

Controls on Mixing-Dependent Denitrification in Hyporheic Zones

NASA Astrophysics Data System (ADS)

Hester, E. T.; Young, K. I.; Widdowson, M. A.

2013-12-01

Interaction of surface water and groundwater in hyporheic sediments of river systems is known to create unique biogeochemical conditions that can attenuate contaminants flowing downstream. Oxygen, carbon, and the contaminants themselves (e.g., excess nitrate) often advect together through the hyporheic zone from sources in surface water. However, the ability of the hyporheic zone to attenuate contaminants in upwelling groundwater plumes as they exit to rivers is less known. Such reactions may be more dependent on mixing of carbon and oxygen sources from surface water with contaminants from deeper groundwater. We simulated hyporheic flow cells and upwelling groundwater together with mixing-dependent denitrification of an upwelling nitrate plume in shallow riverbed sediments using MODFLOW and SEAM3D. For our first set of model scenarios, we set biogeochemical boundary conditions to be consistent with situations where only mixing-dependent denitrification occurred within the model domain. This occurred where dissolved organic carbon (DOC) advecting from surface water through hyporheic flow cells meets nitrate upwelling from deeper groundwater. This would be common where groundwater is affected by septic systems which contribute nitrate that upwells into streams that do not have significant nitrate sources from upstream. We conducted a sensitivity analysis that showed that mixing-dependent denitrification increased with parameters that increase mixing itself, such as the degree of heterogeneity of sediment hydraulic conductivity (K). Mixing-dependent denitrification also increased with certain biogeochemical boundary concentrations such as increasing DOC or decreasing dissolved oxygen (DO) advecting from surface water. For our second set of model scenarios, we set biogeochemical boundary conditions to be consistent with common situations where non-mixing-dependent denitrification also occurred within the model domain. For example, when nitrate concentrations are substantial in water advecting from surface water, non-mixing-dependent denitrification can occur within the hyporheic flow cells. This would be common where surface water and groundwater have high nitrate concentrations in agricultural areas. We conducted a sensitivity analysis for this set of model scenarios as well, to evaluate controls on the relative balance of mixing-dependent and non-mixing-dependent denitrification. We found that non-mixing-dependent denitrification often has higher potential to consume nitrate than mixing-dependent denitrification. This is because non-mixing-dependent denitrification is not confined to the relatively small mixing zone between upwelling groundwater and hyporheic flow cells, and hence often has longer residence times available for consumption of existing oxygen followed by consumption of nitrate. Nevertheless, the potential for hyporheic zones to attenuate upwelling nitrate plumes appears to be substantial, yet is variable depending on geomorphic, hydraulic, and biogeochemical conditions.

Underscreening in concentrated electrolytes.

PubMed

Lee, Alpha A; Perez-Martinez, Carla S; Smith, Alexander M; Perkin, Susan

2017-07-01

Screening of a surface charge by an electrolyte and the resulting interaction energy between charged objects is of fundamental importance in scenarios from bio-molecular interactions to energy storage. The conventional wisdom is that the interaction energy decays exponentially with object separation and the decay length is a decreasing function of ion concentration; the interaction is thus negligible in a concentrated electrolyte. Contrary to this conventional wisdom, we have shown by surface force measurements that the decay length is an increasing function of ion concentration and Bjerrum length for concentrated electrolytes. In this paper we report surface force measurements to test directly the scaling of the screening length with Bjerrum length. Furthermore, we identify a relationship between the concentration dependence of this screening length and empirical measurements of activity coefficient and differential capacitance. The dependence of the screening length on the ion concentration and the Bjerrum length can be explained by a simple scaling conjecture based on the physical intuition that solvent molecules, rather than ions, are charge carriers in a concentrated electrolyte.

The ice-core record - Climate sensitivity and future greenhouse warming

NASA Technical Reports Server (NTRS)

Lorius, C.; Raynaud, D.; Jouzel, J.; Hansen, J.; Le Treut, H.

1990-01-01

The prediction of future greenhouse-gas-warming depends critically on the sensitivity of earth's climate to increasing atmospheric concentrations of these gases. Data from cores drilled in polar ice sheets show a remarkable correlation between past glacial-interglacial temperature changes and the inferred atmospheric concentration of gases such as carbon dioxide and methane. These and other palaeoclimate data are used to assess the role of greenhouse gases in explaining past global climate change, and the validity of models predicting the effect of increasing concentrations of such gases in the atmosphere.

Active Brownian agents with concentration-dependent chemotactic sensitivity.

PubMed

Meyer, Marcel; Schimansky-Geier, Lutz; Romanczuk, Pawel

2014-02-01

We study a biologically motivated model of overdamped, autochemotactic Brownian agents with concentration-dependent chemotactic sensitivity. The agents in our model move stochastically and produce a chemical ligand at their current position. The ligand concentration obeys a reaction-diffusion equation and acts as a chemoattractant for the agents, which bias their motion towards higher concentrations of the dynamically altered chemical field. We explore the impact of concentration-dependent response to chemoattractant gradients on large-scale pattern formation, by deriving a coarse-grained macroscopic description of the individual-based model, and compare the conditions for emergence of inhomogeneous solutions for different variants of the chemotactic sensitivity. We focus primarily on the so-called receptor-law sensitivity, which models a nonlinear decrease of chemotactic sensitivity with increasing ligand concentration. Our results reveal qualitative differences between the receptor law, the constant chemotactic response, and the so-called log law, with respect to stability of the homogeneous solution, as well as the emergence of different patterns (labyrinthine structures, clusters, and bubbles) via spinodal decomposition or nucleation. We discuss two limiting cases, where the model can be reduced to the dynamics of single species: (I) the agent density governed by a density-dependent effective diffusion coefficient and (II) the ligand field with an effective bistable, time-dependent reaction rate. In the end, we turn to single clusters of agents, studying domain growth and determining mean characteristics of the stationary inhomogeneous state. Analytical results are confirmed and extended by large-scale GPU simulations of the individual based model.

Induction of sister chromatid exchanges and inhibition of cellular proliferation in vitro. I. Caffeine

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

Guglielmi, G.E.; Vogt, T.F.; Tice, R.R.

1982-01-01

While many agents have been examined for their ability to induce SCE's, complete dose-response information has often been lacking. We have reexamined the ability of one such compound - caffeine - to induce SCEs and also to inhibit cellular proliferation in human peripheral lymphocytes in vitro. An acute exposure to caffeine prior to the DNA synthetic period did not affect either SCE frequency or the rate of cellular proliferation. Chronic exposure to caffeine throughout the culture period lead to both a dose-dependent increase in SCEs (SCE/sub d/ or doubling dose = 2.4 mM; SCE/sub 10/ or the dose capable ofmore » inducing 10 SCE = 1.4 mM) and a dose-dependent inhibition of cellular proliferation (IC/sub 50/ or the 50% inhibition concentration = 2.6 mM). The relative proportion of first generation metaphase cells, an assessment of proliferative inhibiton, increased linearly with increasing caffeine concentrations. However, SCE frequency increased nonlinearly over the same range of caffeine concentrations. Examination of the ratio of nonsymmetrical to symmetrical SCEs in third generation metaphase cells indicated that caffeine induced SCEs in equal frequency in each of three successive generations. The dependency of SCE induction and cellular proliferative inhibition on caffeine's presence during the DNA synthetic period suggests that caffeine may act as an antimetabolite in normal human cells.« less

Rheology of Carbon Fibre Reinforced Cement-Based Mortar

NASA Astrophysics Data System (ADS)

Banfill, Phillip F. G.; Starrs, Gerry; McCarter, W. John

2008-07-01

Carbon fibre reinforced cement based materials (CFRCs) offer the possibility of fabricating "smart" electrically conductive materials. Rheology of the fresh mix is crucial to satisfactory moulding and fresh CFRC conforms to the Bingham model with slight structural breakdown. Both yield stress and plastic viscosity increase with increasing fibre length and volume concentration. Using a modified Viskomat NT, the concentration dependence of CFRC rheology up to 1.5% fibre volume is reported.

Selected Contribution: Skeletal muscle focal adhesion kinase, paxillin, and serum response factor are loading dependent

NASA Technical Reports Server (NTRS)

Gordon, S. E.; Fluck, M.; Booth, F. W.

2001-01-01

This investigation examined the effect of mechanical loading state on focal adhesion kinase (FAK), paxillin, and serum response factor (SRF) in rat skeletal muscle. We found that FAK concentration and tyrosine phosphorylation, paxillin concentration, and SRF concentration are all lower in the lesser load-bearing fast-twitch plantaris and gastrocnemius muscles compared with the greater load-bearing slow-twitch soleus muscle. Of these three muscles, 7 days of mechanical unloading via tail suspension elicited a decrease in FAK tyrosine phosphorylation only in the soleus muscle and decreases in FAK and paxillin concentrations only in the plantaris and gastrocnemius muscles. Unloading decreased SRF concentration in all three muscles. Mechanical overloading (via bilateral gastrocnemius ablation) for 1 or 8 days increased FAK and paxillin concentrations in the soleus and plantaris muscles. Additionally, whereas FAK tyrosine phosphorylation and SRF concentration were increased by < or =1 day of overloading in the soleus muscle, these increases did not occur until somewhere between 1 and 8 days of overloading in the plantaris muscle. These data indicate that, in the skeletal muscles of rats, the focal adhesion complex proteins FAK and paxillin and the transcription factor SRF are generally modulated in association with the mechanical loading state of the muscle. However, the somewhat different patterns of adaptation of these proteins to altered loading in slow- vs. fast-twitch skeletal muscles indicate that the mechanisms and time course of adaptation may partly depend on the prior loading state of the muscle.

Lithium concentration dependent structure and mechanics of amorphous silicon

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

Sitinamaluwa, H. S.; Wang, M. C.; Will, G.

2016-06-28

A better understanding of lithium-silicon alloying mechanisms and associated mechanical behavior is essential for the design of Si-based electrodes for Li-ion batteries. Unfortunately, the relationship between the dynamic mechanical response and microstructure evolution during lithiation and delithiation has not been well understood. We use molecular dynamic simulations to investigate lithiated amorphous silicon with a focus to the evolution of its microstructure, phase composition, and stress generation. The results show that the formation of Li{sub x}Si alloy phase is via different mechanisms, depending on Li concentration. In these alloy phases, the increase in Li concentration results in reduction of modulus ofmore » elasticity and fracture strength but increase in ductility in tension. For a Li{sub x}Si system with uniform Li distribution, volume change induced stress is well below the fracture strength in tension.« less

Trigeminal induced arousals during human sleep.

PubMed

Heiser, Clemens; Baja, Jan; Lenz, Franziska; Sommer, J Ulrich; Hörmann, Karl; Herr, Raphael M; Stuck, Boris A

2015-05-01

Arousals caused by external stimuli during human sleep have been studied for most of the sensorial systems. It could be shown that a pure nasal trigeminal stimulus leads to arousals during sleep. The frequency of arousals increases dependent on the stimulus concentration. The aim of the study was to evaluate the influence of different stimulus durations on arousal frequency during different sleep stages. Ten young healthy volunteers with 20 nights of polysomnography were included in the study. Pure trigeminal stimulation with both different concentrations of CO2 (0, 10, 20, 40% v/v) and different stimulus durations (1, 3, 5, and 10 s) were applied during different sleep stages to the volunteers using an olfactometer. The application was performed during different sleep stages (light sleep, deep sleep, REM sleep). The number of arousals increased with rising stimulus duration and stimulus concentration during each sleep stage. Trigeminal stimuli during sleep led to arousals in dose- and time-dependent manner.

Effect of co-existing copper and calcium on the removal of As(V) by reused aluminum oxides.

PubMed

Yang, J K; Park, Y J; Kim, K H; Lee, H Y; Min, K C; Lee, S M

2013-01-01

Among the various heavy metals, arsenic is frequently found in abandoned mine drainage and the environmental fate of arsenic in real aqueous solutions can be highly dependent on the presence of co-existing ions. In this study, removal of arsenate through adsorption on the reused aluminum oxide or through precipitation was investigated in a single and in a binary system as a function of pH and concentration. Different removal behaviors of arsenate were observed in the presence of different cations as well as a variation of the molar ratios of arsenate to cations. Co-operative effects on arsenate removal by precipitation in solution occurred with an increase of copper concentration, while a decrease of arsenate removal resulted in increasing calcium concentration. It was observed that the arsenate removal in the presence of calcium would be highly dependent on the molar ratios of both elements.

Base-line O sub 2 extraction influences cerebral blood flow response to hematocrit

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

Hudak, M.L.; Tang, Yuilin; Massik, J.

1988-01-01

The authors have shown that the fall in cerebral blood flow (CBF) as hematocrit (Hct) rises is due to the independent effects of increasing red blood cell (RBC) concentration and arterial O{sub 2} content (Ca{sub O{sub 2}}). In the present study, they tested the hypothesis that the magnitude of the effect of RBC concentration depends on the base-line cerebral fractional oxygen extraction (E). Pentobarbital-anesthetized 1- to 7-day-old sheep were first exchange transfused with plasma to lower Hct to 20%. Base-line E was set to either high or low levels by induction of hypocarbia, or hypercarbia. A second isovolemic exchange transfusionmore » with pure methemoglobin-containing adult sheep red cells then raised Hct with no significant increase in Ca{sub O{sub 2}}. Pa{sub CO{sub 2}} was maintained and other variables with potential effect on CBF did not change. CBF corrected for any individual alteration in CMRo{sub 2}. This study supports the hypothesis that the magnitude of the decline in CBF secondary to an increase in RBC concentration depends on the initial E. The effect of RBC concentration on CBF is greatest when E is low.« less

Dimethyl sulfoxide induces oxidative stress in the yeast Saccharomyces cerevisiae.

PubMed

Sadowska-Bartosz, Izabela; Pączka, Aleksandra; Mołoń, Mateusz; Bartosz, Grzegorz

2013-12-01

Dimethyl sulfoxide (DMSO) is used as a cryoprotectant for the preservation of cells, including yeast, and as a solvent for chemical compounds. We report that DMSO induces oxidative stress in the yeast. Saccharomyces cerevisiae wt strain EG-103 and its mutants Δsod1, Δsod2, and Δsod1 Δsod2 were used. Yeast were subjected to the action of 1-14% DMSO for 1 h at 28 °C. DMSO induced a concentration-dependent inhibition of yeast growth, the effect being more pronounced for mutants devoid of SOD (especially Δsod1 Δsod2). Cell viability was compromised. DMSO-concentration-dependent activity loss of succinate dehydrogenase, a FeS enzyme sensitive to oxidative stress, was observed. DMSO enhanced formation of reactive oxygen species, estimated with dihydroethidine in a concentration-dependent manner, the effect being again more pronounced in mutants devoid of superoxide dismutases. The content of cellular glutathione was increased with increasing DMSO concentrations, which may represent a compensatory response. Membrane fluidity, estimated by fluorescence polarization of DPH, was decreased by DMSO. These results demonstrate that DMSO, although generally considered to be antioxidant, induces oxidative stress in yeast cells. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

Concentration-dependent changes in apparent diffusion coefficients as indicator for colloidal stability of protein solutions.

PubMed

Bauer, Katharina Christin; Göbel, Mathias; Schwab, Marie-Luise; Schermeyer, Marie-Therese; Hubbuch, Jürgen

2016-09-10

The colloidal stability of a protein solution during downstream processing, formulation, and storage is a key issue for the biopharmaceutical production process. Thus, knowledge about colloidal solution characteristics, such as the tendency to form aggregates or high viscosity, at various processing conditions is of interest. This work correlates changes in the apparent diffusion coefficient as a parameter of protein interactions with observed protein aggregation and dynamic viscosity of the respective protein samples. For this purpose, the diffusion coefficient, the protein phase behavior, and the dynamic viscosity in various systems containing the model proteins α-lactalbumin, lysozyme, and glucose oxidase were studied. Each of these experiments revealed a wide range of variations in protein interactions depending on protein type, protein concentration, pH, and the NaCl concentration. All these variations showed to be mirrored by changes in the apparent diffusion coefficient in the respective samples. Whereas stable samples with relatively low viscosity showed an almost linear dependence, the deviation from the concentration-dependent linearity indicated both an increase in the sample viscosity and probability of protein aggregation. This deviation of the apparent diffusion coefficient from concentration-dependent linearity was independent of protein type and solution properties for this study. Thus, this single parameter shows the potential to act as a prognostic tool for colloidal stability of protein solutions. Copyright © 2016 Elsevier B.V. All rights reserved.

The organophosphate insecticide chlorpyrifos confers its genotoxic effects by inducing DNA damage and cell apoptosis.

PubMed

Li, Diqiu; Huang, Qingchun; Lu, Miaoqing; Zhang, Lei; Yang, Zhichuan; Zong, Mimi; Tao, Liming

2015-09-01

The organophosphate insecticide chlorpyrifos (CPF) is known to induce neurological effects, malformation and micronucleus formation, persistent developmental disorders, and maternal toxicity in rats and mice. The binding of chlorpyrifos with DNA to produce DNA adducts leads to an increasing social concern about the genotoxic risk of CPF in human, but CPF-induced cytotoxicity through DNA damage and cell apoptosis is not well understood. Here, we quantified the cytotoxicity and potential genotoxicity of CPF using the alkaline comet assay, γH2AX foci formation, and the DNA laddering assay in order to detect DNA damage and apoptosis in human HeLa and HEK293 cells in vitro. Drosophila S2 cells were used as a positive control. The alkaline comet assay showed that sublethal concentrations of CPF induced significant concentration-dependent increases in single-strand DNA breaks in the treated cells compared with the control. The percentage of γH2AX-positive HeLa cells revealed that CPF also causes DNA double-strand breaks in a time-dependent manner. Moreover, DNA fragmentation analysis demonstrated that exposure to CPF induced a significant concentration- and time-dependent increase in cell apoptosis. We conclude that CPF is a strongly genotoxic agent that induces DNA damage and cell apoptosis. Copyright © 2015 Elsevier Ltd. All rights reserved.

Computational Examination of Orientation-Dependent Morphological Evolution during the Electrodeposition and Electrodissolution of Magnesium

DOE PAGES

DeWitt, S.; Hahn, N.; Zavadil, K.; ...

2015-12-30

Here a new model of electrodeposition and electrodissolution is developed and applied to the evolution of Mg deposits during anode cycling. The model captures Butler-Volmer kinetics, facet evolution, the spatially varying potential in the electrolyte, and the time-dependent electrolyte concentration. The model utilizes a diffuse interface approach, employing the phase field and smoothed boundary methods. Scanning electron microscope (SEM) images of magnesium deposited on a gold substrate show the formation of faceted deposits, often in the form of hexagonal prisms. Orientation-dependent reaction rate coefficients were parameterized using the experimental SEM images. Three-dimensional simulations of the growth of magnesium deposits yieldmore » deposit morphologies consistent with the experimental results. The simulations predict that the deposits become narrower and taller as the current density increases due to the depletion of the electrolyte concentration near the sides of the deposits. Increasing the distance between the deposits leads to increased depletion of the electrolyte surrounding the deposit. Two models relating the orientation-dependence of the deposition and dissolution reactions are presented. Finally, the morphology of the Mg deposit after one deposition-dissolution cycle is significantly different between the two orientation-dependence models, providing testable predictions that suggest the underlying physical mechanisms governing morphology evolution during deposition and dissolution.« less

Effect of chloroquine on insulin and glucose homoeostasis in normal subjects and patients with non-insulin-dependent diabetes mellitus.

PubMed Central

Smith, G D; Amos, T A; Mahler, R; Peters, T J

1987-01-01

Plasma glucose, insulin, and C peptide concentrations were determined after an oral glucose load in normal subjects and in a group of patients with non-insulin-dependent diabetes mellitus before and during a short course of treatment with chloroquine. In the control group there was a small but significant reduction in fasting blood glucose concentration but overall glucose tolerance and hormone concentrations were unaffected. In contrast, the patients with non-insulin-dependent diabetes mellitus showed a significant improvement in their glucose tolerance, which paralleled the severity of their diabetes. This response seems to reflect decreased degradation of insulin rather than increased pancreatic output. These observations suggest that treatment with chloroquine or suitable analogues may be a new approach to the management of diabetes. PMID:3103729

Geochemical controls on microbial nitrate-dependent U(IV) oxidation

USGS Publications Warehouse

Senko, John M.; Suflita, Joseph M.; Krumholz, Lee R.

2005-01-01

After reductive immobilization of uranium, the element may be oxidized and remobilized in the presence of nitrate by the activity of dissimilatory nitrate-reducing bacteria. We examined controls on microbially mediated nitrate-dependent U(IV) oxidation in landfill leachate-impacted subsurface sediments. Nitrate-dependent U(IV)-oxidizing bacteria were at least two orders of magnitude less numerous in these sediments than glucose- or Fe(II)-oxidizing nitrate-reducing bacteria and grew more slowly than the latter organisms, suggesting that U(IV) is ultimately oxidized by Fe(III) produced by nitrate-dependent Fe(II)-oxidizing bacteria or by oxidation of Fe(II) by nitrite that accumulates during organotrophic dissimilatory nitrate reduction. We examined the effect of nitrate and reductant concentration on nitrate-dependent U(IV) oxidation in sediment incubations and used the initial reductive capacity (RDC = [reducing equivalents] - [oxidizing equivalents]) of the incubations as a unified measurement of the nitrate or reductant concentration. When we lowered the RDC with progressively higher nitrate concentrations, we observed a corresponding increase in the extent of U(IV) oxidation, but did not observe this relationship between RDC and U(IV) oxidation rate, especially when RDC > 0, suggesting that nitrate concentration strongly controls the extent, but not the rate of nitrate-dependent U(IV) oxidation. On the other hand, when we raised the RDC in sediment incubations with progressively higher reductant (acetate, sulfide, soluble Fe(II), or FeS) concentrations, we observed progressively lower extents and rates of nitrate-dependent U(IV) oxidation. Acetate was a relatively poor inhibitor of nitrate-dependent U(IV) oxidation, while Fe(II) was the most effective inhibitor. Based on these results, we propose that it may be possible to predict the stability of U(IV) in a bioremediated aquifer based on the geochemical characteristics of that aquifer.

Photoluminescence of Er-doped silicon-rich oxide thin films with high Al concentrations

NASA Astrophysics Data System (ADS)

Rozo, Carlos; Fonseca, Luis F.; Jaque, Daniel; García Solé, José

Er-doped silicon-rich oxide (SRO) thin films co-doped with Al in high concentrations were prepared by sputtering. Some films were deposited using a substrate heater (150 °C

Metabolic response to MMS-mediated DNA damage in Saccharomyces cerevisiae is dependent on the glucose concentration in the medium.

PubMed

Kitanovic, Ana; Walther, Thomas; Loret, Marie Odile; Holzwarth, Jinda; Kitanovic, Igor; Bonowski, Felix; Van Bui, Ngoc; Francois, Jean Marie; Wölfl, Stefan

2009-06-01

Maintenance and adaptation of energy metabolism could play an important role in the cellular ability to respond to DNA damage. A large number of studies suggest that the sensitivity of cells to oxidants and oxidative stress depends on the activity of cellular metabolism and is dependent on the glucose concentration. In fact, yeast cells that utilize fermentative carbon sources and hence rely mainly on glycolysis for energy appear to be more sensitive to oxidative stress. Here we show that treatment of the yeast Saccharomyces cerevisiae growing on a glucose-rich medium with the DNA alkylating agent methyl methanesulphonate (MMS) triggers a rapid inhibition of respiration and enhances reactive oxygen species (ROS) production, which is accompanied by a strong suppression of glycolysis. Further, diminished activity of pyruvate kinase and glyceraldehyde-3-phosphate dehydrogenase upon MMS treatment leads to a diversion of glucose carbon to glycerol, trehalose and glycogen accumulation and an increased flux through the pentose-phosphate pathway. Such conditions finally result in a significant decline in the ATP level and energy charge. These effects are dependent on the glucose concentration in the medium. Our results clearly demonstrate that calorie restriction reduces MMS toxicity through increased respiration and reduced ROS accumulation, enhancing the survival and recovery of cells.

The kinetics of nucleated polymerizations at high concentrations: amyloid fibril formation near and above the "supercritical concentration".

PubMed

Powers, Evan T; Powers, David L

2006-07-01

The formation of amyloid and other types of protein fibrils is thought to proceed by a nucleated polymerization mechanism. One of the most important features commonly associated with nucleated polymerizations is a strong dependence of the rate on the concentration. However, the dependence of fibril formation rates on concentration can weaken and nearly disappear as the concentration increases. Using numerical solutions to the rate equations for nucleated polymerization and analytical solutions to some limiting cases, we examine this phenomenon and show that it is caused by the concentration approaching and then exceeding the equilibrium constant for dissociation of monomers from species smaller than the nucleus, a quantity we have named the "supercritical concentration". When the concentration exceeds the supercritical concentration, the monomer, not the nucleus, is the highest-energy species on the fibril formation pathway, and the fibril formation reaction behaves initially like an irreversible polymerization. We also derive a relation that can be used in a straightforward method for determining the nucleus size and the supercritical concentration from experimental measurements of fibril formation rates.

Plasma growth hormone (GH), insulin and amino acid responses to arginine with or without aspartic acid in pigs. Effect of the dose.

PubMed

Cochard, A; Guilhermet, R; Bonneau, M

1998-01-01

The aim of the present study was to examine, for the first time in pigs, the dose-dependent effect of arginine (ARG) on growth hormone (GH) and insulin release and the effect of the combined ARG and aspartic acid (ASP) treatment on GH and insulin release. ARG (0.5 or 1 g/kg body weight) with or without an equimolar supplement of ASP (0.38 or 0.76 g/kg, respectively) was administered in piglets via the duodenum. ARG increased plasma arginine, ornithine, urea, proline and branched chain amino acid concentrations. ASP increased specifically plasma aspartic acid, glutamic acid, alanine and citrulline concentrations. Plasma insulin increased with no apparent difference between treatments. Maximum GH level and the area under the GH curve (AUC) were increased in a dose-dependent manner in response to ARG treatment. GH response to the combined ARG and ASP treatment (ARGASP) was delayed compared to ARG alone and was not dose-dependent. AUC for GH after ARGASP treatments were intermediate between those observed after the two ARG doses. Our data suggest that high ASP doses transiently inhibit and delay ARG-induced GH release in pigs and that an equimolar supplement of ASP stimulates or inhibits ARG-induced GH release depending on the dose used.

Resistance of Saccharomyces cerevisiae to High Concentrations of Furfural Is Based on NADPH-Dependent Reduction by at Least Two Oxireductases ▿ †

PubMed Central

Heer, Dominik; Heine, Daniel; Sauer, Uwe

2009-01-01

Biofuels derived from lignocellulosic biomass hold promises for a sustainable fuel economy, but several problems hamper their economical feasibility. One important problem is the presence of toxic compounds in processed lignocellulosic hydrolysates, with furfural as a key toxin. While Saccharomyces cerevisiae has some intrinsic ability to reduce furfural to the less-toxic furfuryl alcohol, higher resistance is necessary for process conditions. By comparing an evolved, furfural-resistant strain and its parent in microaerobic, glucose-limited chemostats at increasing furfural challenge, we elucidate key mechanism and the molecular basis of both natural and high-level furfural resistance. At lower concentrations of furfural, NADH-dependent oxireductases are the main defense mechanism. At furfural concentrations above 15 mM, however, 13C-flux and global array-based transcript analysis demonstrated that the NADPH-generating flux through the pentose phosphate pathway increases and that NADPH-dependent oxireductases become the major resistance mechanism. The transcript analysis further revealed that iron transmembrane transport is upregulated in response to furfural. While these responses occur in both strains, high-level resistance in the evolved strain was based on strong induction of ADH7, the uncharacterized open reading frame (ORF) YKL071W, and four further, likely NADPH-dependent, oxireductases. By overexpressing the ADH7 gene and the ORF YKL071W, we inversely engineered significantly increased furfural resistance in the parent strain, thereby demonstrating that these two enzymes are key elements of the resistance phenotype. PMID:19854918

Hydrologic controls on DOC, As and Pb export from a polluted peatland - the importance of heavy rain events, antecedent moisture conditions and hydrological connectivity

NASA Astrophysics Data System (ADS)

Broder, T.; Biester, H.

2015-03-01

Bogs can store large amounts of lead (Pb) and arsenic (As) attributed to atmospheric deposition of anthropogenic emissions. Pb and As are exported along with dissolved organic carbon (DOC) in these organic-rich systems, but it is not yet clear which hydrological (pre-)conditions favor their export. This study combines one year continuous monitoring of precipitation, bog water level and pore water concentration changes with bog discharge, DOC, As and Pb stream concentrations and fluxes. Concentrations ranged from 5 to 30 mg L-1 for DOC, 0.2 to 1.9 μg L-1 for As and 1.3 to 12 μg L-1 for Pb with highest concentrations in late summer. As and Pb concentrations significantly correlated with DOC concentrations. Fluxes depended strongly on discharge, as 40% of As and 43% of Pb were exported by the upper 10% of discharge, pointing out the over-proportional contribution of heavy rain and high discharge events to annual As, Pb and DOC export. Exponential increase in element export from the bog is explained by connection of additional DOC, As and Pb pools in the acrotelm during water table rise, which is most pronounced after drought. Pb, As and DOC concentrations in pore water provide evidence of an increase of the soluble Pb pool as soon as the peat layer gets hydrologically connected, while DOC and As peak concentrations in runoff lag in comparison to Pb. Our data indicates a distinct bog-specific discharge threshold of 8 L s-1, which is thought to depend mainly on the bogs size and drainage conditions. Above this threshold element concentration do not further increase and discharge gets diluted. Combining pore water and discharge data shows that As and Pb exports are not only dependent on the amount of precipitation and discharge, but on the frequency and depth of water table fluctuations. Comparing the annual bog As and Pb export with element inventories indicates that As is much more mobilized than Pb, with annual fluxes accounting for 0.85 and 0.27‰ of total As and Pb inventory, respectively.

Modulation of JB6 Mouse Epidermal Cell Transformation Response by the Prostaglandin F2 Alpha Receptor

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

Weber, Thomas J.; Markillie, Lye MENG.; Chrisler, William B.

2002-12-01

Prostaglandin F2a (PGF2a) has been associated with the modulation of clonal selection processes in the mouse skin model of carcinogenesis. We have investigated whether JB6 mouse epidermal cells express a functional PGF2a receptor (FP) coupled to the regulation of anchorage-dependent and -independent growth. Treatment of JB6 cells with a FP receptor ligand (fluprostenol) potently (pM-nM) increased anchorage-dependent and -independent growth, as determined by a battery of in vitro assays. Treatment of JB6 cells with PGF2a and fluprostenol increased inositol phospholipid accumulation and extracellular signal regulated kinase (ERK) activity, consistent with FP receptor-related signaling. FP receptor mRNA was detected by reversemore » transcription-polymerase chain reaction and a radiolabel binding assay determined the average specific [3H]PGF2a binding to be 8.25 + 0.95 fmol/mg protein. Treatment of cells with fluprostenol as a single exposure resulted in a significant increase in anchorage-dependent and -independent growth in media containing low (0.1-0.5%), but not high (5%) concentrations of fetal bovine serum (FBS). In contrast, treatment of cells with fluprostenol at two day intervals resulted in a more robust growth response under anchorage-dependent conditions only in media containing low FBS concentrations; and under anchorage-independent conditions only in media containing high FBS concentrations. ERK activation and colony size were increased by cotreatment of JB6 cells with EGF and fluprostenol to a greater extent than either treatment alone, while the cotreatment effect on colony number appeared to be simply additive. In summary, FBS concentration and signal oscillation exert pronounced effects on the biological response to a FP receptor agonist. The data raise the possibility that the FP receptor may independently contribute to clonal selection processes, but may play a more important role as a response modifier.« less

Concentration and size dependence of peak wavelength shift on quantum dots in colloidal suspension

NASA Astrophysics Data System (ADS)

Rinehart, Benjamin S.; Cao, Caroline G. L.

2016-08-01

Quantum dots (QDs) are semiconductor nanocrystals that have significant advantages over organic fluorophores, including their extremely narrow Gaussian emission bands and broad absorption bands. Thus, QDs have a wide range of potential applications, such as in quantum computing, photovoltaic cells, biological sensing, and electronics. For these applications, aliasing provides a detrimental effect on signal identification efficiency. This can be avoided through characterization of the QD fluorescence signals. Characterization of the emissivity of CdTe QDs as a function of concentration (1 to 10 mg/ml aqueous) was conducted on 12 commercially available CdTe QDs (emission peaks 550 to 730 nm). The samples were excited by a 50-mW 405-nm laser with emission collected via a free-space CCD spectrometer. All QDs showed a redshift effect as concentration increased. On average, the CdTe QDs exhibited a maximum shift of +35.6 nm at 10 mg/ml and a minimum shift of +27.24 nm at 1 mg/ml, indicating a concentration dependence for shift magnitude. The concentration-dependent redshift function can be used to predict emission response as QD concentration is changed in a complex system.

Permeation and gating properties of the L-type calcium channel in mouse pancreatic beta cells

PubMed Central

1993-01-01

Ba2+ currents through L-type Ca2+ channels were recorded from cell- attached patches on mouse pancreatic beta cells. In 10 mM Ba2+, single- channel currents were recorded at -70 mV, the beta cell resting membrane potential. This suggests that Ca2+ influx at negative membrane potentials may contribute to the resting intracellular Ca2+ concentration and thus to basal insulin release. Increasing external Ba2+ increased the single-channel current amplitude and shifted the current-voltage relation to more positive potentials. This voltage shift could be modeled by assuming that divalent cations both screen and bind to surface charges located at the channel mouth. The single- channel conductance was related to the bulk Ba2+ concentration by a Langmuir isotherm with a dissociation constant (Kd(gamma)) of 5.5 mM and a maximum single-channel conductance (gamma max) of 22 pS. A closer fit to the data was obtained when the barium concentration at the membrane surface was used (Kd(gamma) = 200 mM and gamma max = 47 pS), which suggests that saturation of the concentration-conductance curve may be due to saturation of the surface Ba2+ concentration. Increasing external Ba2+ also shifted the voltage dependence of ensemble currents to positive potentials, consistent with Ba2+ screening and binding to membrane surface charge associated with gating. Ensemble currents recorded with 10 mM Ca2+ activated at more positive potentials than in 10 mM Ba2+, suggesting that external Ca2+ binds more tightly to membrane surface charge associated with gating. The perforated-patch technique was used to record whole-cell currents flowing through L-type Ca2+ channels. Inward currents in 10 mM Ba2+ had a similar voltage dependence to those recorded at a physiological Ca2+ concentration (2.6 mM). BAY-K 8644 (1 microM) increased the amplitude of the ensemble and whole-cell currents but did not alter their voltage dependence. Our results suggest that the high divalent cation solutions usually used to record single L-type Ca2+ channel activity produce a positive shift in the voltage dependence of activation (approximately 32 mV in 100 mM Ba2+). PMID:7687645

Dependence of Non-Prestonian Behavior of Ceria Slurry with Anionic Surfactant on Abrasive Concentration and Size in Shallow Trench Isolation Chemical Mechanical Polishing

NASA Astrophysics Data System (ADS)

Kang, Hyun‑Goo; Kim, Dae‑Hyeong; Katoh, Takeo; Kim, Sung‑Jun; Paik, Ungyu; Park, Jea‑Gun

2006-05-01

The dependencies of the non-Prestonian behavior of ceria slurry with anionic surfactant on the size and concentration of abrasive particles were investigated by performing chemical mechanical polishing (CMP) experiments using blanket wafers. We found that not only the abrasive size but also the abrasive concentration with surfactant addition influences the non-Prestonian behavior. Such behavior is clearly exhibited with small abrasive sizes and a higher concentrations of abrasives with surfactant addition, because the abrasive particles can locally contact the film surface more effectively with applied pressure. We introduce a factor to quantify these relations with the non-Prestonian behavior of a slurry. For ceria slurry, this non-Prestonian factor, βNP, was determined to be almost independent of the abrasive concentration for a larger size and a smaller weight conentration of abrasive particles, but it increased with the surfactant concentration for a smaller size and a higher concentration of abrasives with surfactant addition.

Effects of concentration, temperature and solvent composition on density and apparent molar volume of the binary mixtures of cationic-anionic surfactants in methanol-water mixed solvent media.

PubMed

Bhattarai, Ajaya; Chatterjee, Sujeet Kumar; Niraula, Tulasi Prasad

2013-01-01

The accurate measurements on density of the binary mixtures of cetyltrimethylammonium bromide and sodium dodecyl sulphate in pure water and in methanol(1) + water (2) mixed solvent media containing (0.10, 0.20, and 0.30) volume fractions of methanol at 308.15, 318.15, and 323.15 K are reported. The concentrations are varied from (0.03 to 0.12) mol.l(-1) of sodium dodecyl sulphate in presence of ~ 5.0×10(-4) mol.l(-1) cetyltrimethylammonium bromide. The results showed almost increase in the densities with increasing surfactant mixture concentration, also the densities are found to decrease with increasing temperature over the entire concentration range, investigated in a given mixed solvent medium and these values are found to decrease with increasing methanol content in the solvent composition. The concentration dependence of the apparent molar volumes appear to be negligible over the entire concentration range, investigated in a given mixed solvent medium and the apparent molar volumes increase with increasing temperature and are found to decrease with increasing methanol content in the solvent composition.

Molecular Dynamics Simulation of Surface Tension of NaCl Aqueous Solution at 298.15K: from Diluted to Highly Supersaturated Concentrations

NASA Astrophysics Data System (ADS)

Wang, Xiaoxiang; Chen, Chuchu; Poeschl, Ulirch; Su, Hang; Cheng, Yafang

2017-04-01

Sodium chloride (NaCl) is one of the key components of atmospheric aerosol particles. Concentration-depend surface tension of aqueous NaCl solution is essential to determine the equilibrium between droplet NaCl solution and water vapor, which is important in regards to aerosol-cloud interaction and aerosol climate effects. Although supersaturated NaCl droplets can be widely found under atmospheric conditions, the experimental determined concentration dependency of surface tension is limited up to the saturated concentration range due to technical difficulties, i.e., heterogeneous nucleation since nearly all surface tension measurement techniques requires contact of the sensor and solution surface. In this study, the surface tension of NaCl aqueous solution with solute mass fraction from 0 to 1 was calculated using molecular dynamics (MD) simulation. The surface tension increases monotonically and near linearly when mass fraction of NaCl (xNaCl) is lower than 0.265 (saturation point), which follows theoretical predictions (e.g., E-AIM, SP parameterization, and PK parameterization). Once entering into the supersaturated concentration range, the calculated surface tension starts to deviate from the near-linear extrapolation and adopts a slightly higher increasing rate until xNaCl of 0.35. We found that these two increasing phases (xNaCl 0.35) is mainly driven by the increase of excessive surface enthalpy when the solution becomes concentrated. After that, the surface tension remains almost unchanged until xNaCl of 0.52. This phenomenon is supported by the results from experiment based Differential Koehler Analyses. The stable surface tension in this concentration range is attributed to a simultaneous change of surface excess enthalpy and entropy at similar degree. When the NaCl solution is getting more concentrated than xNaCl of 0.52, the simulated surface tension regains an even faster growing momentum and shows the tendency of ultimately approaching the surface tension of molten NaCl at 298.15 K ( 148.4 mN/m by MD simulation). Energetic analyses imply that this fast increase is primarily still an excessive surface enthalpy-driven process, although concurrent fluctuation of excessive surface entropy is also expected but in a much smaller scale. Our results unfold the global landscape of concentration dependence of aqueous NaCl solution and its driven forces: a water surface tension dominated regime (xNaCl from 0 to 0.35), a transition regime (xNaCl from 0.35 to 0.52) and a molten NaCl surface tension dominated regime (xNaCl beyond 0.52).

Urea-Induced Unfolding of the Immunity Protein Im9 Monitored by spFRET

PubMed Central

Tezuka-Kawakami, Tomoko; Gell, Chris; Brockwell, David J.; Radford, Sheena E.; Smith, D. Alastair

2006-01-01

We have studied the urea-induced unfolding of the E colicin immunity protein Im9 using diffusion single-pair fluorescence resonance energy transfer. Detailed examination of the proximity ratio of the native and denatured molecules over a wide range of urea concentrations suggests that the conformational properties of both species are denaturant-dependent. Whereas native molecules become gradually more expanded as urea concentration increases, denatured molecules show a dramatic dependence of the relationship between proximity ratio and denaturant concentration, consistent with substantial compaction of the denatured ensemble at low denaturant concentrations. Analysis of the widths of the proximity ratio distributions for each state suggests that whereas the native state ensemble is relatively narrow and homogeneous, the denatured state may possess heterogeneity in mildly denaturing conditions. PMID:16798813

Electrodiffusive Model for Astrocytic and Neuronal Ion Concentration Dynamics

PubMed Central

Halnes, Geir; Østby, Ivar; Pettersen, Klas H.; Omholt, Stig W.; Einevoll, Gaute T.

2013-01-01

The cable equation is a proper framework for modeling electrical neural signalling that takes place at a timescale at which the ionic concentrations vary little. However, in neural tissue there are also key dynamic processes that occur at longer timescales. For example, endured periods of intense neural signaling may cause the local extracellular K+-concentration to increase by several millimolars. The clearance of this excess K+ depends partly on diffusion in the extracellular space, partly on local uptake by astrocytes, and partly on intracellular transport (spatial buffering) within astrocytes. These processes, that take place at the time scale of seconds, demand a mathematical description able to account for the spatiotemporal variations in ion concentrations as well as the subsequent effects of these variations on the membrane potential. Here, we present a general electrodiffusive formalism for modeling of ion concentration dynamics in a one-dimensional geometry, including both the intra- and extracellular domains. Based on the Nernst-Planck equations, this formalism ensures that the membrane potential and ion concentrations are in consistency, it ensures global particle/charge conservation and it accounts for diffusion and concentration dependent variations in resistivity. We apply the formalism to a model of astrocytes exchanging ions with the extracellular space. The simulations show that K+-removal from high-concentration regions is driven by a local depolarization of the astrocyte membrane, which concertedly (i) increases the local astrocytic uptake of K+, (ii) suppresses extracellular transport of K+, (iii) increases axial transport of K+ within astrocytes, and (iv) facilitates astrocytic relase of K+ in regions where the extracellular concentration is low. Together, these mechanisms seem to provide a robust regulatory scheme for shielding the extracellular space from excess K+. PMID:24367247

Effects of calcium channel blockers on the kinetics of voltage-dependent changes in synaptosomal calcium concentrations.

PubMed

Thomas, M M; Puligandla, P S; Dunn, S M

1994-01-28

Synaptosomal preparations from rat cerebral cortex have been used in stopped-flow fluorescence studies to measure rapid changes in intrasynaptosomal calcium concentrations upon depolarization. Synaptosomes were loaded with the fluorescent calcium chelating dye, Fura-2, by incubation with the membrane permeant acetoxymethyl ester derivative. Depolarization by elevated external K+ concentration resulted in a rapid increase in cytoplasmic Ca2+ as measured by a quench in Fura-2 fluorescence when excited at 390 nm. The fluorescence change could be reasonably fit by a single exponential process with an apparent rate of 10-15 s-1 and the magnitude of the response was voltage-dependent, increasing with increasing external K+ over the range of 5-30 mM. The observed quench was blocked by micromolar concentrations of the inorganic calcium channel blockers, Cd2+, Co2+ and La3+. Nimodipine, a dihydropyridine which blocks L-type calcium channels, inhibited only 10-15% of the flux response while nitrendipine had no consistent effect. omega-Conotoxin GVIA, a blocker of N-type channels in many species, had only a small inhibitory effect at high (1-10 microM) concentrations. The response was, however, inhibited by pre-incubation of the synaptosomes with venom of the funnel web spider. Agelenopsis aperta (0.1-300 micrograms/ml). Inhibition was observed with both a purified polyamine fraction (FTX) from the venom (IC50 = 4 nl/ml) and a purified peptide toxin, omega-AgaIVA (IC50 = 30 nM). These results indicate that voltage-dependent Ca2+ uptake by mammalian nerve terminals is mediated primarily by channels that are insensitive to dihydropyridines and omega-conotoxin GVIA but are sensitive to components of funnel web spider venom.

Ebselen alters mitochondrial physiology and reduces viability of rat hippocampal astrocytes.

PubMed

Santofimia-Castaño, Patricia; Salido, Ginés M; González, Antonio

2013-04-01

The seleno-organic compound and radical scavenger ebselen (2-phenyl-1,2-benzisoselenazol-3(2H)-one) have been extensively employed as an anti-inflammatory and neuroprotective compound. However, its glutathione peroxidase activity at the expense of cellular thiols groups could underlie certain deleterious actions of the compound on cell physiology. In this study, we have analyzed the effect of ebselen on rat hippocampal astrocytes in culture. Cellular viability, the intracellular free-Ca(2+) concentration ([Ca(2+)]c), the mitochondrial free-Ca(2+) concentration ([Ca(2+)]m), and mitochondrial membrane potential (ψm) were analyzed. The caspase-3 activity was also assayed. Our results show that cell viability was reduced by treatment of cells with ebselen, depending on the concentration employed. In the presence of ebselen, we observed an initial transient increase in [Ca(2+)]c that was then followed by a progressive increase to an elevated plateau. We also observed a transient increase in [Ca(2+)]m in the presence of ebselen that returned toward a value over the prestimulation level. The compound induced depolarization of ψm and altered the permeability of the mitochondrial membrane. Additionally, a disruption of the mitochondrial network was observed. Finally, we did not detect changes in caspase-3 activation in response to ebselen treatment. Collectively, these data support the likelihood of ebselen, depending on the concentration employed, reduces viability of rat hippocampal astrocytes via its action on the mitochondrial activity. These may be early effects that do not involve caspase-3 activation. We conclude that, depending on the concentration used, ebselen might exert deleterious actions on astrocyte physiology that could compromise cell function.

Bisphenol S impairs blood functions and induces cardiovascular risks in rats.

PubMed

Pal, Sanghamitra; Sarkar, Kaushik; Nath, Partha Pratim; Mondal, Mukti; Khatun, Ashma; Paul, Goutam

2017-01-01

Bisphenol S (BPS) is an industrial chemical which is recently used to replace the potentially toxic Bisphenol A (BPA) in making polycarbonate plastics, epoxy resins and thermal receipt papers. The probable toxic effects of BPS on the functions of haemopoietic and cardiovascular systems have not been reported till to date. We report here that BPS depresses haematological functions and induces cardiovascular risks in rat. Adult male albino rats of Sprague-Dawley strain were given BPS at a dose level of 30, 60 and 120 mg/kg BW/day respectively for 30 days. Red blood cell (RBC) count, white blood cell (WBC) count, Hb concentration, and clotting time have been shown to be significantly (*P < 0.05) reduced in a dose dependent manner in all exposed groups of rats comparing to the control. It has also been shown that BPS increases total serum glucose and protein concentration in the exposed groups of rats. We have observed that BPS increases serum total cholesterol, triglyceride, glycerol free triglyceride, low density lipoprotein (LDL) and very low density lipoprotein (VLDL) concentration, whereas high density lipoprotein (HDL) concentration has been found to be reduced in the exposed groups. BPS significantly increases serum aspartate aminotransferase (AST), alanine aminotransferase (ALT) and alkaline phosphatase (ALP) activities dose dependently. Moreover, serum calcium, bilirubin and urea concentration have been observed to be increased in all exposed groups. In conclusion, BPS probably impairs the functions of blood and promotes cardiovascular risks in rats.

The essential oil of bergamot enhances the levels of amino acid neurotransmitters in the hippocampus of rat: implication of monoterpene hydrocarbons.

PubMed

Morrone, Luigi A; Rombolà, Laura; Pelle, Cinzia; Corasaniti, Maria T; Zappettini, Simona; Paudice, Paolo; Bonanno, Giambattista; Bagetta, Giacinto

2007-04-01

The effects of bergamot essential oil (BEO) on the release of amino acid neurotransmitters in rat hippocampus have been studied by in vivo microdialysis and by in vitro superfusion of isolated nerve terminals. Intraperitoneal administration of BEO (100microl/kg) significantly elevated the extracellular concentration of aspartate, glycine and taurine in a Ca(2+)-dependent manner. A dose-relation study generated a bell-shaped curve. When perfused into the hippocampus via the dialysis probe (20microl/20min), BEO produced a significant increase of extracellular aspartate, glycine, taurine as well as of GABA and glutamate. The augmentation of all amino acids was Ca(2+)-independent. Focally injected 1:1 diluted BEO preferentially caused extracellular increase of glutamate. Interestingly, this release appeared to be strictly Ca(2+)-dependent. BEO concentration-dependently enhanced the release of [(3)H]D-aspartate from superfused hippocampal synaptosomes. Similar results were obtained by monitoring the BEO-evoked release of endogenous glutamate. At relatively high concentrations, the BEO-induced [(3)H]d-aspartate release was almost entirely prevented by the glutamate transporter blocker dl-threo-beta-benzyloxyaspartic acid (DL-TBOA) and was Ca(2+)-independent. At relatively low concentrations the release of [(3)H]D-aspartate was only in part ( approximately 50%) DL-TBOA-sensitive and Ca(2+)-independent; the remaining portion of release was dependent on extracellular Ca(2+). Interestingly, the monoterpene hydrocarbon-free fraction of the essential oil appeared to be inactive while the bergapten-free fraction superimposed the releasing effect of BEO supporting the deduction that psoralens may not be implicated. To conclude, BEO contains into its volatile fraction still unidentified monoterpene hydrocarbons able to stimulate glutamate release by transporter reversal and/or by exocytosis, depending on the dose administered.

Pre-Steady-State Kinetics of Ba-Ca Exchange Reveals a Second Electrogenic Step Involved in Ca2+ Translocation by the Na-Ca Exchanger

PubMed Central

Haase, Andreas; Hartung, Klaus

2009-01-01

Kinetic properties of the Na-Ca exchanger (guinea pig NCX1) expressed in Xenopus oocytes were investigated with excised membrane patches in the inside-out configuration and photolytic Ca2+ concentration jumps with either 5 mM extracellular Sr2+ or Ba2+. After a Ca2+ concentration jump on the cytoplasmic side, the exchanger performed Sr-Ca or Ba-Ca exchange. In the Sr-Ca mode, currents are transient and decay in a monoexponential manner similar to that of currents in the Ca-Ca exchange mode described before. Currents recorded in the Ba-Ca mode are also transient, but the decay is biphasic. In the Sr-Ca mode the amount of charge translocated increases at negative potentials in agreement with experiments performed in the Ca-Ca mode. In the Ba-Ca mode the total amount of charge translocated after a Ca2+ concentration jump is ∼4 to 5 times that in Ca-Ca or Sr-Ca mode. In the Ba-Ca mode the voltage dependence of charge translocation depends on the Ca2+ concentration on the cytosolic side before the Ca2+ concentration jump. At low initial Ca2+ levels (∼0.5 μM), charge translocation is voltage independent. At a higher initial concentration (1 μM Ca2+), the amount of charge translocated increases at positive potentials. Biphasic relaxation of the current was also observed in the Ca-Ca mode if the external Ca2+ concentration was reduced to ≤0.5 mM. The results reported here and in previous publications can be described by using a 6-state model with two voltage-dependent conformational transitions. PMID:19486679

Culture growth of testate amoebae under different silicon concentrations.

PubMed

Wanner, Manfred; Seidl-Lampa, Barbara; Höhn, Axel; Puppe, Daniel; Meisterfeld, Ralf; Sommer, Michael

2016-10-01

Testate amoebae with self-secreted siliceous shell platelets ("idiosomes") play an important role in terrestrial silicon (Si) cycles. In this context, Si-dependent culture growth dynamics of idiosomic testate amoebae are of interest. Clonal cultures of idiosomic testate amoebae were analyzed under three different Si concentrations: low (50μmolL -1 ), moderate/site-specific (150μmolL -1 ) and high Si supply (500μmolL -1 ). Food (Saccharomyces cerevisiae) was provided in surplus. (i) Shell size of four different clones of idiosomic testate amoebae either decreased (Trinema galeata, Euglypha filifera cf.), increased (E. rotunda cf.), or did not change (E. rotunda) under the lowest Si concentration (50μmolSiL -1 ). (ii) Culture growth of idiosomic Euglypha rotunda was dependent on Si concentration. The more Si available in the culture medium, the earlier the entry into exponential growth phase. (iii) Culture growth of idiosomic Euglypha rotunda was dependent on origin of inoculum. Amoebae previously cultured under a moderate Si concentration revealed highest sustainability in consecutive cultures. Amoebae derived from cultures with high Si concentrations showed rapid culture growth which finished early in consecutive cultures. (iv) Si (diluted in the culture medium) was absorbed by amoebae and fixed in the amoeba shells resulting in decreased Si concentrations. Copyright © 2016 Elsevier GmbH. All rights reserved.

Impact of radon gas concentration in the aerosoles profile

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

Lukaj, Edmond, E-mail: mondilukaj@yahoo.com; Vila, Floran, E-mail: floranvila@yahoo.com; Mandija, Florian, E-mail: fmandija@yahoo.com

Radon gases relased from building materials and from earth surface are the major responsibility of air ionization. Radon nuclear decay can produce an alpha particle with high energy and Radon progeny. This particle and gamma rays can deliver particles in the air and produce ions with different polarities. This ions, because of induced electric charge, can attach with air aerosols and charge them with their electric charge. The charged aerosols can interact with the other aerosols and ions. Because of this exchange, the air conductivity and the aerosol profiles will change dependently by Radon gas concentration and gamma radiation. Observationsmore » show an increase in concentration of Radon during the night, and a decrease during the daylight time. The Radon gas concentration changed hour by hour can induce aerosol profile to change. This dependency between the aerosol profiles and the Radon gas concentrations is discussed.« less

Microphysiometric analysis of human α1a-adrenoceptor expressed in Chinese hamster ovary cells

PubMed Central

Taniguchi, Takanobu; Inagaki, Rika; Murata, Satoshi; Akiba, Isamu; Muramatsu, Ikunobu

1999-01-01

The human recombinant α1a-adrenoceptor (AR) has been stably expressed in Chinese hamster ovary cells. Four stable clones, aH4, aH5, aH6 and aH7, expressing 30, 370, 940 and 2900 fmol AR mg−1 protein, respectively, have been employed to characterize this AR subtype using radioligand binding and microphysiometry to measure extracellular acidification rates.Noradrenaline (NA) gave concentration-dependent responses in microphysiometry with increasing extracellular acidification rates. The potency of NA increased as the receptor density increased; pEC50 values of NA for the clones aH4, aH5, aH6 and aH7 were 6.9, 7.5, 7.8 and 8.1, respectively. This increase of potency according to receptor density indicates the presence of spare receptor for NA. Methoxamine, phenylephrine, oxymetazoline and clonidine also gave concentration-dependent responses with various intrinsic activities.Antagonists shifted concentration-response curves for NA rightward in a concentration-dependent manner. Schild analysis revealed that the affinity profile of this AR subtype to antagonists in the clone aH7 had a typical pattern for the α1a-AR; high affinity for prazosin and WB 4101, and low affinity for BMY7378 (pA2=9.5, 9.8 and 7.3, respectively). This profile is similar in the case of the clone aH4. These affinities were in good agreement with those obtained in binding experiments.These results have demonstrated that (1) classical receptor theory can be applied in microphysiometry, and (2) microphysiometry is a useful tool to investigate the pharmacological characterization of α1a-AR. PMID:10433504

Assessment of phosphamidon-induced apoptosis in human peripheral blood mononuclear cells: protective effects of N-acetylcysteine and curcumin.

PubMed

Ahmed, Tanzeel; Tripathi, Ashok K; Ahmed, Rafat S; Banerjee, Basu Dev

2010-01-01

The molecular mechanism for noncholinergic toxicity of phosphamidon, an extensively used organophosphate pesticide, is still not clear. The aim of the present study is to find the possible molecular mechanism of this pesticide to induce apoptosis and the role of different drugs for attenuation of such effects. Human peripheral blood mononuclear cells (PBMC) were incubated with increasing concentrations of phosphamidon (0-20 μM) for 6-24 h. The MTT assay reveals that phosphamidon induces cytotoxicity in a dose-dependent manner. Cellular glutathione (GSH) is depleted in a dose-dependent manner from 55% to 70% at concentrations between 10 and 20 μM. The percentage of cells that bind to Annexin-V, which is a representative of cells either undergoing apoptosis or necrosis during 24 h incubation, increases in a dose-dependent manner. Above 5 μM, significant necrosis of cells was observed. DNA fragmentation assay revealed that at low concentration of phosphamidon (1 μM), no appreciable change in DNA fragmentation was seen; however, distinct fragmentation was observed beyond 2.5 μM. Phosphamidon was found to cause significant depletion of GSH, which correlates well with the percentage of cells undergoing apoptosis. An increasing trend in levels of cytochrome c was observed with increasing concentration of phosphamidon, indicating that the apoptotic effect of phosphamidon is mediated through cytochrome c release. Coadministration of the antioxidants N-acetylcysteine and curcumin attenuated phosphamidon-induced apoptosis. This further supports our hypothesis that oxidative stress, as indicated by GSH depletion, results in the induction of apoptosis by release of cytochrome c. Copyright 2010 Wiley Periodicals, Inc.

Confocal spectroscopic imaging measurements of depth dependent hydration dynamics in human skin in-vivo

NASA Astrophysics Data System (ADS)

Behm, P.; Hashemi, M.; Hoppe, S.; Wessel, S.; Hagens, R.; Jaspers, S.; Wenck, H.; Rübhausen, M.

2017-11-01

We present confocal spectroscopic imaging measurements applied to in-vivo studies to determine the depth dependent hydration profiles of human skin. The observed spectroscopic signal covers the spectral range from 810 nm to 2100 nm allowing to probe relevant absorption signals that can be associated with e.g. lipid and water-absorption bands. We employ a spectrally sensitive autofocus mechanism that allows an ultrafast focusing of the measurement spot on the skin and subsequently probes the evolution of the absorption bands as a function of depth. We determine the change of the water concentration in m%. The water concentration follows a sigmoidal behavior with an increase of the water content of about 70% within 5 μm in a depth of about 14 μm. We have applied our technique to study the hydration dynamics of skin before and after treatment with different concentrations of glycerol indicating that an increase of the glycerol concentration leads to an enhanced water concentration in the stratum corneum. Moreover, in contrast to traditional corneometry we have found that the application of Aluminium Chlorohydrate has no impact to the hydration of skin.

Proximal renal tubular injury in rats sub-chronically exposed to low fluoride concentrations

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

Cárdenas-González, Mariana C.; Del Razo, Luz M.; Barrera-Chimal, Jonatan

2013-11-01

Fluoride is usually found in groundwater at a very wide range of concentration between 0.5 and 25 ppm. At present, few studies have assessed the renal effects of fluoride at environmentally relevant concentrations. Furthermore, most of these studies have used insensitive and nonspecific biomarkers of kidney injury. The aim of this study was to use early and sensitive biomarkers to evaluate kidney injury after fluoride exposure to environmentally relevant concentrations. Recently weaned male Wistar rats were exposed to low (15 ppm) and high (50 ppm) fluoride concentrations in drinking water for a period of 40 days. At the end ofmore » the exposure period, kidney injury biomarkers were measured in urine and renal mRNA expression levels were assessed by real time RT-PCR. Our results showed that the urinary kidney injury molecule (Kim-1), clusterin (Clu), osteopontin (OPN) and heat shock protein 72 excretion rate significantly increased in the group exposed to the high fluoride concentration. Accordingly, fluoride exposure increased renal Kim-1, Clu and OPN mRNA expression levels. Moreover, there was a significant dose-dependent increase in urinary β-2-microglobulin and cystatin-C excretion rate. Additionally, a tendency towards a dose dependent increase of tubular damage in the histopathological light microscopy findings confirmed the preferential impact of fluoride on the tubular structure. All of these changes occurred at early stages in which, the renal function was not altered. In conclusion using early and sensitive biomarkers of kidney injury, we were able to found proximal tubular alterations in rats sub-chronically exposed to fluoride. - Highlights: • Exposure to low concentrations of fluoride induced proximal tubular injury • Increase in urinary Kim-1, Clu, OPN and Hsp72 in 50 ppm fluoride-exposed group • Increase in urinary B2M and CysC in 15 and 50 ppm fluoride-exposed groups • Fluoride exposure increased renal Kim, Clu and OPN mRNA expression levels. • Fluoride increased kidney injury biomarkers at stages where eGFR was unaltered.« less

The Effects of Urban Form on Ambient Air Pollution and Public Health Risk: A Case Study in Raleigh, North Carolina

PubMed Central

Rodriguez, Daniel A.; Huegy, Joseph; Gibson, Jacqueline MacDonald

2014-01-01

Since motor vehicles are a major air pollution source, urban designs that decrease private automobile use could improve air quality and decrease air pollution health risks. Yet, the relationships among urban form, air quality, and health are complex and not fully understood. To explore these relationships, we model the effects of three alternative development scenarios on annual average fine particulate matter (PM2.5) concentrations in ambient air and associated health risks from PM2.5 exposure in North Carolina’s Raleigh-Durham-Chapel Hill area. We integrate transportation demand, land-use regression, and health risk assessment models to predict air quality and health impacts for three development scenarios: current conditions, compact development, and sprawling development. Compact development slightly decreases (−0.2%) point estimates of regional annual average PM2.5 concentrations, while sprawling development slightly increases (+1%) concentrations. However, point estimates of health impacts are in opposite directions: compact development increases (+39%) and sprawling development decreases (−33%) PM2.5-attributable mortality. Further, compactness increases local variation in PM2.5 concentrations and increases the severity of local air pollution hotspots. Hence, this research suggests that while compact development may improve air quality from a regional perspective, it may also increase the concentration of PM2.5 in local hotspots and increase population exposure to PM2.5. Health effects may be magnified if compact neighborhoods and PM2.5 hotspots are spatially co-located. We conclude that compactness alone is an insufficient means of reducing the public health impacts of transportation emissions in automobile-dependent regions. Rather, additional measures are needed to decrease automobile dependence and the health risks of transportation emissions. PMID:25490890

Effects of biochar on enhanced nutrient use efficiency of green bean, Vigna radiata L.

PubMed

Prapagdee, Songkrit; Tawinteung, Nukoon

2017-04-01

Biochar is the carbonized material produced from biomass and is used in several environmental applications. The biochar characteristics depend on the carbonization conditions and feedstock. The suitability of a given biochar for soil improvement depends on the biochar characteristics, soil properties, and target plants. Biochar has been applied at 1-20% (w/w) in the soil, but currently there is a lack of information on what type and concentration of biochar are most suitable for a specific plant and soil quality. Too much biochar will reduce plant growth because of the high alkalinity of biochar, which will cause long-term soil alkalinity. In contrast, too little biochar might be insufficient to enhance plant productivity. In this study, a suitable concentration of cassava stem (an abundant agricultural waste in Thailand) biochar produced at 350 °C was evaluated for green bean (Vigna radiata L.) growth from germination to seed production in pots over 8 weeks. The soil fertility was increased with increasing biochar concentration. At 5% (w/w) biochar, the soil fertility and plant growth were significantly enhanced, while 10% (w/w) biochar significantly enhanced bean growth and bean pod production. The increased biochar concentration in the soil significantly increased the soil total nitrogen and extractable potassium (K) levels but did not affect the amount of available phosphorous. Biochar at 10% (w/w) significantly induced the accumulation of K in the stems, leaves, nut shells, and roots but not in nut seeds. Moreover, biochar not only increased the K concentration in soil but also increased the plant nutrient use efficiency of K, which is important for plant growth. Graphical abstract ᅟ.

The effect of medium viscosity on kinetics of ATP hydrolysis by the chloroplast coupling factor CF1.

PubMed

Malyan, Alexander N

2016-05-01

The coupling factor CF1 is a catalytic part of chloroplast ATP synthase which is exposed to stroma whose viscosity is many-fold higher than that of reaction mixtures commonly used to measure kinetics of CF1-catalyzed ATP hydrolysis. This study is focused on the effect of medium viscosity modulated by sucrose or bovine serum albumin (BSA) on kinetics of Ca(2+)- and Mg(2+)-dependent ATP hydrolysis by CF1. These agents were shown to reduce the maximal rate of Ca(2+)-dependent ATPase without changing the apparent Michaelis constant (К m), thus supporting the hypothesis on viscosity dependence of CF1 activity. For the sulfite- and ethanol-stimulated Mg(2+)-dependent reaction, the presence of sucrose increased К m without changing the maximal rate that is many-fold as high as that of Ca(2+)-dependent hydrolysis. The hydrolysis reaction was shown to be stimulated by low concentrations of BSA and inhibited by its higher concentrations, with the increasing maximal reaction rate estimated by extrapolation. Sucrose- or BSA-induced inhibition of the Mg(2+)-dependent ATPase reaction is believed to result from diffusion-caused deceleration, while its BSA-induced stimulation is probably caused by optimization of the enzyme structure. Molecular mechanisms of the inhibitory effect of viscosity are discussed. Taking into account high protein concentrations in the chloroplast stroma, it was suggested that kinetic parameters of ATP hydrolysis, and probably those of ATP synthesis in vivo as well, must be quite different from measurements taken at a viscosity level close to that of water.

Bimodal dielectric relaxation of electrolyte solutions in weakly polar solvents.

PubMed

Yamaguchi, Tsuyoshi; Koda, Shinobu

2014-12-28

The dielectric relaxation spectra of dilute electrolyte solutions in solvents of small dielectric constants are investigated both theoretically and experimentally. The theoretical calculation in our previous work [T. Yamaguchi, T. Matsuoka, and S. Koda, J. Chem. Phys. 135, 164511 (2011)] is reanalyzed, and it is shown that the dielectric relaxation spectra are composed of three components, namely, the relaxation of ionic atmosphere, the reorientational relaxation of ion pairs, and the collision between ions. The relaxation frequency of the slowest one increases with increasing the concentration, and the slower two relaxations, those of ionic atmosphere and ion pairs, merge into one at the concentration where the Debye length is comparable to the size of ions. Experimentally, the dielectric relaxation spectra of some electrolytes in two solvents, tetrahydrofuran and tetraglyme, are determined at frequencies from 300 kHz to 200 MHz, and the presence of the slower two relaxations was confirmed. The concentration dependence of the relaxation frequency is also in harmony with the theoretical calculation. The relationship between the dielectric relaxation spectra and the concentration dependence of the ionic conductivity is discussed.

Bimodal dielectric relaxation of electrolyte solutions in weakly polar solvents

NASA Astrophysics Data System (ADS)

Yamaguchi, Tsuyoshi; Koda, Shinobu

2014-12-01

The dielectric relaxation spectra of dilute electrolyte solutions in solvents of small dielectric constants are investigated both theoretically and experimentally. The theoretical calculation in our previous work [T. Yamaguchi, T. Matsuoka, and S. Koda, J. Chem. Phys. 135, 164511 (2011)] is reanalyzed, and it is shown that the dielectric relaxation spectra are composed of three components, namely, the relaxation of ionic atmosphere, the reorientational relaxation of ion pairs, and the collision between ions. The relaxation frequency of the slowest one increases with increasing the concentration, and the slower two relaxations, those of ionic atmosphere and ion pairs, merge into one at the concentration where the Debye length is comparable to the size of ions. Experimentally, the dielectric relaxation spectra of some electrolytes in two solvents, tetrahydrofuran and tetraglyme, are determined at frequencies from 300 kHz to 200 MHz, and the presence of the slower two relaxations was confirmed. The concentration dependence of the relaxation frequency is also in harmony with the theoretical calculation. The relationship between the dielectric relaxation spectra and the concentration dependence of the ionic conductivity is discussed.

Near-infrared studies of glucose and sucrose in aqueous solutions: water displacement effect and red shift in water absorption from water-solute interaction.

PubMed

Jung, Youngeui; Hwang, Jungseek

2013-02-01

We used near infrared spectroscopy to obtain concentration dependent glucose absorption spectra in aqueous solutions in the near-infrared range (3800-7500 cm(-1)). Here we introduce a new method to obtain reliable glucose absorption bands from aqueous glucose solutions without measuring the water displacement coefficients of glucose separately. Additionally, we were able to extract the water displacement coefficients of glucose, and this may offer a new general method using spectroscopy techniques applicable to other water-soluble materials. We also observed red shifts in the absorption bands of water in the hydration shell around solute molecules, which comes from the contribution of the interacting water molecules around the glucose molecules in solutions. The intensity of the red shift gets larger as the concentration increases, which indicates that as the concentration increases more water molecules are involved in the interaction. However, the red shift in frequency does not seem to depend significantly on the concentration. We also performed the same measurements and analysis with sucrose instead of glucose as solute and compared.

Modulation of interleukin-1 secretion by immunosuppressive drugs, alone and in combination.

PubMed

Reisman, L; Lin, W G; Martinelli, G P

1995-03-01

This study evaluates the ability of the immunosuppressive drugs dexamethasone, cyclosporine, FK506 and rapamycin, alone and in combination to suppress interleukin-1 beta (IL-1 beta) secretion in vitro by THP-1 cells when stimulated by lipopolysaccharide. All four drugs, when added to cell culture medium at therapeutic concentrations, significantly decrease secretion of the monokine to well below control levels. However, only dexamethasone completely suppresses IL-1 beta secretion in a dose-dependent fashion. Cyclosporine, FK506 and rapamycin only partially suppress secretion of IL-1 beta at concentrations within their therapeutic ranges and increasing concentrations of the drugs do not result in further suppression of secretion. Likewise, the combination of any two of these three drugs does not provide any additional suppressive effect. Dexamethasone, however, when added in increasing concentrations in combination with any of the other drugs, results in further suppression of IL-1 secretion in a dose-dependent fashion. These data suggest that cyclosporine, FK506 and rapamycin all share a common effect on the production of IL-1 beta, different from that of dexamethasone.

Supercooling of aqueous NaCl and KCl solutions under acoustic levitation.

PubMed

Lü, Y J; Wei, B

2006-10-14

The supercooling capability of aqueous NaCl and KCl solutions is investigated at containerless state by using acoustic levitation method. The supercooling of water is obviously enhanced by the alkali metal ions and increases linearly with the augmentation of concentrations. Furthermore, the supercooling depends on the nature of ions and is 2-3 K larger for NaCl solution than that for KCl solution in the present concentration range: Molecular dynamics simulations are performed to reveal the intrinsic correlation between supercoolability and microstructure. The translational and orientational order parameters are applied to quantitatively demonstrate the effect of ionic concentration on the hydrogen-bond network and ice melting point. The disrupted hydrogen-bond structure determines essentially the concentration dependence of supercooling. On the other hand, the introduced acoustic pressure suppresses the increase of supercooling by promoting the growth and coalescence of microbubbles, the effective nucleation catalysts, in water. However, the dissolved ions can weaken this effect, and moreover the degree varies with the ion type. This results in the different supercoolability for NaCl and KCl solutions under the acoustic levitation conditions.

Natural Mineral Particles Are Cytotoxic to Rainbow Trout Gill Epithelial Cells In Vitro

PubMed Central

de Capitani, Christian; Burkhardt-Holm, Patricia; Pietsch, Constanze

2014-01-01

Worldwide increases in fluvial fine sediment are a threat to aquatic animal health. Fluvial fine sediment is always a mixture of particles whose mineralogical composition differs depending on the sediment source and catchment area geology. Nonetheless, whether particle impact in aquatic organisms differs between mineral species remains to be investigated. This study applied an in vitro approach to evaluate cytotoxicity and uptake of four common fluvial mineral particles (quartz, feldspar, mica, and kaolin; concentrations: 10, 50, 250 mg L−1) in the rainbow trout epithelial gill cell line RTgill-W1. Cells were exposed for 24, 48, 72, and 96 h. Cytotoxicity assays for cell membrane integrity (propidium iodide assay), oxidative stress (H2DCF-DA assay), and metabolic activity (MTT assay) were applied. These assays were complemented with cell counts and transmission electron microscopy. Regardless of mineral species, particles ≤2 µm in diameter were taken up by the cells, suggesting that particles of all mineral species came into contact and interacted with the cells. Not all particles, however, caused strong cytotoxicity: Among all assays the tectosilicates quartz and feldspar caused sporadic maximum changes of 0.8–1.2-fold compared to controls. In contrast, cytotoxicity of the clay particles was distinctly stronger and even differed between the two particle types: mica induced concentration-dependent increases in free radicals, with consistent 1.6–1.8-fold-changes at the 250 mg L−1 concentration, and a dilated endoplasmic reticulum. Kaolin caused concentration-dependent increases in cell membrane damage, with consistent 1.3–1.6-fold increases at the 250 mg L−1 concentration. All effects occurred in the presence or absence of 10% fetal bovine serum. Cell numbers per se were marginally affected. Results indicate that (i.) natural mineral particles can be cytotoxic to gill epithelial cells, (ii.) their cytotoxic potential differs between mineral species, with clay particles being more cytotoxic, and (iii.) some clays might induce effects comparable to engineered nanoparticles. PMID:24991818

Concentration-Dependent Inhibitory Effect of Baicalin on the Plasma Protein Binding and Metabolism of Chlorzoxazone, a CYP2E1 Probe Substrate, in Rats In Vitro and In Vivo

PubMed Central

Gao, Na; Zou, Dan; Qiao, Hai-Ling

2013-01-01

Some of the components found in herbs may be inhibitors or inducers of cytochrome P450 enzymes, which may therefore result in undesired herb-drug interactions. As a component extracted from Radix Scutellariae, the direct effect of baicalin on cytochrome P450 has not been investigated sufficiently. In this study, we investigated concentration-dependent inhibitory effect of baicalin on the plasma protein binding and metabolism of chlorzoxazone (CZN), a model CYP2E1 probe substrate, in rats in vitro and in vivo. Animal experiment was a randomized, three-period crossover design. Significant changes in pharmacokinetic parameters of CZN such as Cmax, t1/2 and Vd were observed after treatment with baicalin in vivo (P<0.05). Cmax decreased by 25% and 33%, whereas t1/2 increased by 34% and 53%, Vd increased by 37% and 50% in 225 mg/kg and 450 mg/kg baicalin-treated rats, respectively. The AUC and CL of CZN were not affected (P>0.05). Correlation analysis showed that the changes in CZN concentrations and baicalin concentrations were in good correlation (r>0.99). In vitro experiments, baicalin decreased the formation of 6-OH-chlorzoxazone in a concentration-dependent manner and exhibited a competitive inhibition in rat liver microsomes, with a Ki value of 145.8 µM. The values of Cmax/Ki were 20 and 39 after treatment with baicalin (225 and 450 mg/kg), respectively. Protein binding experiments in vivo showed that the plasma free-fraction (fu) of CZN increased 2.6-fold immediately after baicalin treatment (450 mg/kg) and in vitro showed that baicalin (125–2500 mg/L) increased the unbound CZN from 1.63% to 3.58%. The results indicate that pharmacokinetic changes in CZN are induced by inhibitory effect of baicalin on the plasma protein binding of CZN and CYP2E1 activity. PMID:23301016

Slow-Down in Diffusion in Crowded Protein Solutions Correlates with Transient Cluster Formation.

PubMed

Nawrocki, Grzegorz; Wang, Po-Hung; Yu, Isseki; Sugita, Yuji; Feig, Michael

2017-12-14

For a long time, the effect of a crowded cellular environment on protein dynamics has been largely ignored. Recent experiments indicate that proteins diffuse more slowly in a living cell than in a diluted solution, and further studies suggest that the diffusion depends on the local surroundings. Here, detailed insight into how diffusion depends on protein-protein contacts is presented based on extensive all-atom molecular dynamics simulations of concentrated villin headpiece solutions. After force field adjustments in the form of increased protein-water interactions to reproduce experimental data, translational and rotational diffusion was analyzed in detail. Although internal protein dynamics remained largely unaltered, rotational diffusion was found to slow down more significantly than translational diffusion as the protein concentration increased. The decrease in diffusion is interpreted in terms of a transient formation of protein clusters. These clusters persist on sub-microsecond time scales and follow distributions that increasingly shift toward larger cluster size with increasing protein concentrations. Weighting diffusion coefficients estimated for different clusters extracted from the simulations with the distribution of clusters largely reproduces the overall observed diffusion rates, suggesting that transient cluster formation is a primary cause for a slow-down in diffusion upon crowding with other proteins.

Soil Solution Phosphorus Status and Mycorrhizal Dependency in Leucaena leucocephala.

PubMed

Habte, M; Manjunath, A

1987-04-01

A phosphorus sorption isotherm was used to establish concentrations of P in a soil solution ranging from 0.002 to 0.807 mug/ml. The influence of P concentration on the symbiotic interaction between the tropical tree legume Leucaena leucocephala and the vesicular-arbuscular mycorrhizal (VAM) fungus Glomus fasciculatum was evaluated in pot experiments. The level of mycorrhizal infection in Leucaena roots increased as the concentration of P was raised from 0.002 to 0.153 mug/ml. Higher levels of P depressed mycorrhizal infection, but the level of infection never declined below 50%. Periodic monitoring of P contents of Leucaena subleaflets indicated that significant mycorrhizal activity was detected as early as 17 days after planting, with the activity peaking 12 to 16 days thereafter. The highest level of mycorrhizal activity was associated with a soil solution P level of 0.021 mug/ml. Even though the mycorrhizal inoculation effect diminished as the concentration of P in the soil solution was increased, mycorrhizal inoculation significantly increased P uptake and dry-matter yield of Leucaena at all levels of soil solution P examined. The concentration of P required by nonmycorrhizal L. leucocephala for maximum yield was 27 to 38 times higher than that required by mycorrhizal L. leucocephala. The results illustrate the very high dependence of L. leucocephala on VAM fungi and the significance of optimizing soil solution phosphorus for enhancing the benefits of the VAM symbiosis.

Rapid frequency‐dependent changes in free mitochondrial calcium concentration in rat cardiac myocytes

PubMed Central

Wüst, Rob C. I.; Helmes, Michiel; Martin, Jody L.; van der Wardt, Thomas J. T.; Musters, René J. P.; van der Velden, Jolanda

2017-01-01

Key points Calcium ions regulate mitochondrial ATP production and contractile activity and thus play a pivotal role in matching energy supply and demand in cardiac muscle.The magnitude and kinetics of the changes in free mitochondrial calcium concentration in cardiac myocytes are largely unknown.Rapid stimulation frequency‐dependent increases but relatively slow decreases in free mitochondrial calcium concentration were observed in rat cardiac myocytes. This asymmetry caused a rise in the mitochondrial calcium concentration with stimulation frequency.These results provide insight into the mechanisms of mitochondrial calcium uptake and release that are important in healthy and diseased myocardium. Abstract Calcium ions regulate mitochondrial ATP production and contractile activity and thus play a pivotal role in matching energy supply and demand in cardiac muscle. Little is known about the magnitude and kinetics of the changes in free mitochondrial calcium concentration in cardiomyocytes. Using adenoviral infection, a ratiometric mitochondrially targeted Förster resonance energy transfer (FRET)‐based calcium indicator (4mtD3cpv, MitoCam) was expressed in cultured adult rat cardiomyocytes and the free mitochondrial calcium concentration ([Ca2+]m) was measured at different stimulation frequencies (0.1–4 Hz) and external calcium concentrations (1.8–3.6 mm) at 37°C. Cytosolic calcium concentrations were assessed under the same experimental conditions in separate experiments using Fura‐4AM. The increases in [Ca2+]m during electrical stimulation at 0.1 Hz were rapid (rise time = 49 ± 2 ms), while the decreases in [Ca2+]m occurred more slowly (decay half time = 1.17 ± 0.07 s). Model calculations confirmed that this asymmetry caused the rise in [Ca2+]m during diastole observed at elevated stimulation frequencies. Inhibition of the mitochondrial sodium–calcium exchanger (mNCE) resulted in a rise in [Ca2+]m at baseline and, paradoxically, in an acceleration of Ca2+ release. In conclusion: rapid increases in [Ca2+]m allow for fast adjustment of mitochondrial ATP production to increases in myocardial demand on a beat‐to‐beat basis and mitochondrial calcium release depends on mNCE activity and mitochondrial calcium buffering. PMID:28028811

Functional Relationship between Sucrose and a Cariogenic Biofilm Formation

PubMed Central

Cai, Jian-Na; Jung, Ji-Eun; Dang, Minh-Huy; Kim, Mi-Ah; Yi, Ho-Keun; Jeon, Jae-Gyu

2016-01-01

Sucrose is an important dietary factor in cariogenic biofilm formation and subsequent initiation of dental caries. This study investigated the functional relationships between sucrose concentration and Streptococcus mutans adherence and biofilm formation. Changes in morphological characteristics of the biofilms with increasing sucrose concentration were also evaluated. S. mutans biofilms were formed on saliva-coated hydroxyapatite discs in culture medium containing 0, 0.05, 0.1, 0.5, 1, 2, 5, 10, 20, or 40% (w/v) sucrose. The adherence (in 4-hour biofilms) and biofilm composition (in 46-hour biofilms) of the biofilms were analyzed using microbiological, biochemical, laser scanning confocal fluorescence microscopic, and scanning electron microscopic methods. To determine the relationships, 2nd order polynomial curve fitting was performed. In this study, the influence of sucrose on bacterial adhesion, biofilm composition (dry weight, bacterial counts, and water-insoluble extracellular polysaccharide (EPS) content), and acidogenicity followed a 2nd order polynomial curve with concentration dependence, and the maximum effective concentrations (MECs) of sucrose ranged from 0.45 to 2.4%. The bacterial and EPS bio-volume and thickness in the biofilms also gradually increased and then decreased as sucrose concentration increased. Furthermore, the size and shape of the micro-colonies of the biofilms depended on the sucrose concentration. Around the MECs, the micro-colonies were bigger and more homogeneous than those at 0 and 40%, and were surrounded by enough EPSs to support their structure. These results suggest that the relationship between sucrose concentration and cariogenic biofilm formation in the oral cavity could be described by a functional relationship. PMID:27275603

Bioaccumulation and toxicity of selenium compounds in the green alga Scenedesmus quadricauda

PubMed Central

Umysová, Dáša; Vítová, Milada; Doušková, Irena; Bišová, Kateřina; Hlavová, Monika; Čížková, Mária; Machát, Jiří; Doucha, Jiří; Zachleder, Vilém

2009-01-01

Background Selenium is a trace element performing important biological functions in many organisms including humans. It usually affects organisms in a strictly dosage-dependent manner being essential at low and toxic at higher concentrations. The impact of selenium on mammalian and land plant cells has been quite extensively studied. Information about algal cells is rare despite of the fact that they could produce selenium enriched biomass for biotechnology purposes. Results We studied the impact of selenium compounds on the green chlorococcal alga Scenedesmus quadricauda. Both the dose and chemical forms of Se were critical factors in the cellular response. Se toxicity increased in cultures grown under sulfur deficient conditions. We selected three strains of Scenedesmus quadricauda specifically resistant to high concentrations of inorganic selenium added as selenite (Na2SeO3) – strain SeIV, selenate (Na2SeO4) – strain SeVI or both – strain SeIV+VI. The total amount of Se and selenomethionine in biomass increased with increasing concentration of Se in the culturing media. The selenomethionine made up 30–40% of the total Se in biomass. In both the wild type and Se-resistant strains, the activity of thioredoxin reductase, increased rapidly in the presence of the form of selenium for which the given algal strain was not resistant. Conclusion The selenium effect on the green alga Scenedesmus quadricauda was not only dose dependent, but the chemical form of the element was also crucial. With sulfur deficiency, the selenium toxicity increases, indicating interference of Se with sulfur metabolism. The amount of selenium and SeMet in algal biomass was dependent on both the type of compound and its dose. The activity of thioredoxin reductase was affected by selenium treatment in dose-dependent and toxic-dependent manner. The findings implied that the increase in TR activity in algal cells was a stress response to selenium cytotoxicity. Our study provides a new insight into the impact of selenium on green algae, especially with regard to its toxicity and bioaccumulation. PMID:19445666

Dietary saturated triacylglycerols suppress hepatic low density lipoprotein receptor activity in the hamster.

PubMed

Spady, D K; Dietschy, J M

1985-07-01

The liver plays a key role in the regulation of circulating levels of low density lipoproteins (LDL) because it is both the site for the production of and the major organ for the degradation of this class of lipoproteins. In this study, the effects of feeding polyunsaturated or saturated triacylglycerols on receptor-dependent and receptor-independent hepatic LDL uptake were measured in vivo in the hamster. In control animals, receptor-dependent LDL transport manifested an apparent Km value of 85 mg/dl (plasma LDL-cholesterol concentration) and reached a maximum transport velocity of 131 micrograms of LDL-cholesterol/hr per g, whereas receptor-independent uptake increased as a linear function of plasma LDL levels. Thus, at normal plasma LDL-cholesterol concentrations, the hepatic clearance rate of LDL equaled 120 and 9 microliter/hr per g by receptor-dependent and receptor-independent mechanisms, respectively. As the plasma LDL-cholesterol was increased, the receptor-dependent (but not the receptor-independent) component declined. When cholesterol (0.12%) alone or in combination with polyunsaturated triacylglycerols was fed for 30 days, receptor-dependent clearance was reduced to 36-42 microliter/hr per g, whereas feeding of cholesterol plus saturated triacylglycerols essentially abolished receptor-dependent LDL uptake (5 microliter/hr per g). When compared to the appropriate kinetic curves, these findings indicated that receptor-mediated LDL transport was suppressed approximately equal to 30% by cholesterol feeding alone and this was unaffected by the addition of polyunsaturated triacylglycerols to the diet. In contrast, receptor-dependent uptake was suppressed approximately equal to 90% by the intake of saturated triacylglycerols. As compared to polyunsaturated triacylglycerols, the intake of saturated lipids was also associated with significantly higher plasma LDL-cholesterol concentrations and lower levels of cholesteryl esters in the liver.

The potential impact on atmospheric ozone and temperature of increasing trace gas concentrations

NASA Technical Reports Server (NTRS)

Brasseur, G.; Derudder, A.

1987-01-01

The response of the atmosphere to emissions of chlorofluorocarbons (CFCs) and other chlorocarbons, and to increasing concentrations of other radiatively active trace gases such as CO2, CH4, and N2O is calculated by a coupled chemical-radiative transport one-dimensional model. It is shown that significant reductions in the ozone concentration and in the temperature are expected in the upper stratosphere as a result of increasing concentrations of active chlorine produced by photodecomposition of the CFCs. The ozone content is expected to increase in the troposphere, as a consequence of increasing concentrations of methane and nitrogen oxides. Due to enhanced greenhouse effects, the Earth's surface should warm up by several degrees. The amplitude and even the sign of future changes in the ozone column are difficult to predict as they are strongly scenario-dependent. An early detection system to prevent noticeable ozone changes as a result of increasing concentrations of source gases should thus be based on a continuous monitoring of the ozone amount in the upper stratosphere rather than on measurements of the ozone column only. Measurements of NOx, Clx, and HOx are also required for unambiguous trend detection and interpretation.

Effects of L-arabinose efflux on λ Red recombination-mediated gene knockout in multiple-antimicrobial-resistant Salmonella enterica serovar Choleraesuis.

PubMed

Liao, Shi-Wei; Lee, Jen-Jie; Ptak, Christopher P; Wu, Ying-Chen; Hsuan, Shih-Ling; Kuo, Chih-Jung; Chen, Ter-Hsin

2018-03-01

In this study, six swine-derived multiple-antimicrobial-resistant (MAR) strains of Salmonella Choleraesuis (S. Choleraesuis) were demonstrated to possess higher efflux pump activity than the wild-type (WT). L-Arabinose, a common inducer for gene expression, modulated S. Choleraesuis efflux pump activity in a dose-dependent manner. At low L-arabinose concentrations, increasing L-arabinose led to a corresponding increase in fluorophore efflux, while at higher L-arabinose concentrations, increasing L-arabinose decreased fluorophore efflux activity. The WT S. Choleraesuis that lacks TolC (ΔtolC), an efflux protein associated with bacterial antibiotic resistance and virulence, was demonstrated to possess a significantly reduced ability to extrude L-arabinose. Further, due to the rapid export of L-arabinose, an efficient method for recombination-mediated gene knockout, the L-arabinose-inducible bacteriophage λ Red recombinase system, has a reduced recombination frequency (~ 12.5%) in clinically isolated MAR Salmonella strains. An increased recombination frequency (up to 60%) can be achieved using a higher concentration of L-arabinose (fivefold) for genetic manipulation and functional analysis for MAR Salmonella using the λ Red system. The study suggests that L-arabinose serves not only as an inducer of the TolC-dependent efflux system but also acts as a competitive substrate of the efflux system. In addition, understanding the TolC-dependent efflux of L-arabinose should facilitate the optimization of L-arabinose induction in strains with high efflux activity.

Microalgal cell disruption via ultrasonic nozzle spraying.

PubMed

Wang, M; Yuan, W

2015-01-01

The objective of this study was to understand the effect of operating parameters, including ultrasound amplitude, spraying pressure, nozzle orifice diameter, and initial cell concentration on microalgal cell disruption and lipid extraction in an ultrasonic nozzle spraying system (UNSS). Two algal species including Scenedesmus dimorphus and Nannochloropsis oculata were evaluated. Experimental results demonstrated that the UNSS was effective in the disruption of microalgal cells indicated by significant changes in cell concentration and Nile red-stained lipid fluorescence density between all treatments and the control. It was found that increasing ultrasound amplitude generally enhanced cell disruption and lipid recovery although excessive input energy was not necessary for best results. The effect of spraying pressure and nozzle orifice diameter on cell disruption and lipid recovery was believed to be dependent on the competition between ultrasound-induced cavitation and spraying-generated shear forces. Optimal cell disruption was not always achieved at the highest spraying pressure or biggest nozzle orifice diameter; instead, they appeared at moderate levels depending on the algal strain and specific settings. Increasing initial algal cell concentration significantly reduced cell disruption efficiency. In all UNSS treatments, the effectiveness of cell disruption and lipid recovery was found to be dependent on the algal species treated.

Phenylethylamine induces an increase in cytosolic Ca2+ in yeast.

PubMed

Pinontoan, Reinhard; Krystofova, Svetlana; Kawano, Tomonori; Mori, Izumi C; Tsuji, Frederick I; Iida, Hidetoshi; Muto, Shoshi

2002-05-01

Beta-phenylethylamine (PEA) induced an increase in cytosolic free calcium ion concentration ([Ca2+]c) in Saccharomyces cerevisiae cells monitored with transgenic aequorin, a Ca2+-dependent photoprotein. The PEA-induced [Ca2+]c increase was dependent on the concentrations of PEA applied, and the Ca2+ mostly originated from an extracellular source. Preceding the Ca2+ influx, H2O2 was generated in the cells by the addition of PEA. Externally added H2O2 also induced a [Ca2+]c increase. These results suggest that PEA induces the [Ca2+]c increase via H2O2 generation. The PEA-induced [Ca2+]c increase occurred in the mid1 mutant with a slightly smaller peak than in the wild-type strain, indicating that Mid1, a stretch-activated nonselective cation channel, may not be mainly involved in the PEA-induced Ca2+ influx. When PEA was applied, the MATa mid1 mutant was rescued from alpha-factor-induced death in a Ca2+-limited medium, suggesting that the PEA-induced [Ca2+]c increase can reinforce calcium signaling in the mating pheromone response pathway.

The Kinetics of Nucleated Polymerizations at High Concentrations: Amyloid Fibril Formation Near and Above the “Supercritical Concentration”

PubMed Central

Powers, Evan T.; Powers, David L.

2006-01-01

The formation of amyloid and other types of protein fibrils is thought to proceed by a nucleated polymerization mechanism. One of the most important features commonly associated with nucleated polymerizations is a strong dependence of the rate on the concentration. However, the dependence of fibril formation rates on concentration can weaken and nearly disappear as the concentration increases. Using numerical solutions to the rate equations for nucleated polymerization and analytical solutions to some limiting cases, we examine this phenomenon and show that it is caused by the concentration approaching and then exceeding the equilibrium constant for dissociation of monomers from species smaller than the nucleus, a quantity we have named the “supercritical concentration”. When the concentration exceeds the supercritical concentration, the monomer, not the nucleus, is the highest-energy species on the fibril formation pathway, and the fibril formation reaction behaves initially like an irreversible polymerization. We also derive a relation that can be used in a straightforward method for determining the nucleus size and the supercritical concentration from experimental measurements of fibril formation rates. PMID:16603497

The effect on endothelial function of vitamin C during methionine induced hyperhomocysteinaemia.

PubMed

Hanratty, C G; McGrath, L T; McAuley, D F; Young, I S; Johnston, D G

2001-01-01

Manipulation of total homocysteine concentration with oral methionine is associated with impairment of endothelial-dependent vasodilation. This may be caused by increased oxidative stress. Vitamin C is an aqueous phase antioxidant vitamin and free radical scavenger. We hypothesised that if the impairment of endothelial function related to experimental hyperhomocysteinaemia was free radically mediated then co-administration of vitamin C should prevent this. Ten healthy adults took part in this crossover study. Endothelial function was determined by measuring forearm blood flow (FBF) in response to intra-arterial infusion of acetylcholine (endothelial-dependent) and sodium nitroprusside (endothelial-independent). Subjects received methionine (100 mg/Kg) plus placebo tablets, methionine plus vitamin C (2 g orally) or placebo drink plus placebo tablets. Study drugs were administered at 9 am on each study date, a minimum of two weeks passed between each study. Homocysteine (tHcy) concentration was determined at baseline and after 4 hours. Endothelial function was determined at 4 hours. Responses to the vasoactive substances are expressed as the area under the curve of change in FBF from baseline. Data are mean plus 95% Confidence Intervals. Following oral methionine tHcy concentration increased significantly versus placebo. At this time endothelial-dependent responses were significantly reduced compared to placebo (31.2 units [22.1-40.3] vs. 46.4 units [42.0-50.8], p < 0.05 vs. Placebo). Endothelial-independent responses were unchanged. Co-administration of vitamin C did not alter the increase in homocysteine or prevent the impairment of endothelial-dependent responses (31.4 [19.5-43.3] vs. 46.4 units [42.0-50.8], p < 0.05 vs. Placebo) This study demonstrates that methionine increased tHcy with impairment of the endothelial-dependent vasomotor responses. Administration of vitamin C did not prevent this impairment and our results do not support the hypothesis that the endothelial impairment is mediated by adverse oxidative stress.

Lanthanum Affects Bell Pepper Seedling Quality Depending on the Genotype and Time of Exposure by Differentially Modifying Plant Height, Stem Diameter and Concentrations of Chlorophylls, Sugars, Amino Acids, and Proteins.

PubMed

García-Jiménez, Atonaltzin; Gómez-Merino, Fernando C; Tejeda-Sartorius, Olga; Trejo-Téllez, Libia I

2017-01-01

Lanthanum (La) is considered a beneficial element, capable of inducing hormesis. Hormesis is a dose-response relationship phenomenon characterized by low-dose stimulation and high-dose inhibition. Herein we tested the effect of 0 and 10 μM La on growth and biomolecule concentrations of seedlings of four sweet bell pepper ( Capsicum annuum L.) varieties, namely Sven, Sympathy, Yolo Wonder, and Zidenka. Seedling evaluations were performed 15 and 30 days after treatment applications (dat) under hydroponic greenhouse conditions. Seedling height was significantly increased by La, growing 20% taller in Yolo Wonder plants, in comparison to the control. Similarly, La significantly enhanced shoot diameter, with increases of 9 and 9.8% in measurements performed 15 and 30 dat, respectively, as compared to the control. Likewise, La-treated seedlings had a higher number of flower buds than the control. An increase in the number of leaves because of La application was observed in Yolo Wonder seedlings, both 15 and 30 dat, while leaf area was augmented in this variety only 30 dat. Nevertheless, La did not affect dry biomass accumulation. La effects on biomolecule concentration were differential over time. In all varieties, La stimulated the biosynthesis of chlorophyll a, b and total 15 dat, though 30 dat only the varieties Sympathy and Yolo Wonder showed enhanced concentrations of these molecules because of La. Total soluble sugars increased in La-treated seedlings 30 dat. Interestingly, while most varieties exposed to La showed a reduction in amino acid concentration 15 dat, the opposite trend was observed 30 dat. Importantly, in all varieties evaluated, La stimulated soluble protein concentration 30 dat. It is important to note that while chlorophyll concentrations increased in all varieties exposed to La, both 15 and 30 dat, those of soluble sugars and proteins consistently increased only 30 dat, but not 15 dat. Our results confirm that La may improve seedling quality by enhancing some growth parameters and biomolecule concentrations, depending on the genotype, and time of exposure.

Regulation of synthesis and activity of NAD(+)-dependent 15-hydroxy-prostaglandin dehydrogenase (15-PGDH) by dexamethasone and phorbol ester in human erythroleukemia (HEL) cells

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

Xun, C.Q.; Ensor, C.M.; Tai, H.H.

1991-06-28

Dexamethasone stimulated 15-PGDH activity in HEL cells in a time and concentration dependent manner. Increase in 15-PGDH activity by dexamethasone was found to be accompanied by an increase in enzyme synthesis as revealed by Western blot and (35S)methionine labeling studies. In addition to dexamethasone, other anti-inflammatory steroids also increased 15-PGDH activity in the order of their glucocorticoid activity. Among sex steroids only progesterone increased significantly 15-PGDH activity. 12-0-Tetradecanoylphorbol-13-acetate (TPA) also induced the synthesis of 15-PGDH but inhibited the enzyme activity. It appears that TPA caused a time dependent inactivation of 15-PGDH by a protein kinase C mediated mechanism.

Effect of 1,25-dihydroxyvitamin D3 on plasma concentrations of calcium-binding protein in normal and rachitic (vitamin D-dependent rickets type I) pigs.

PubMed

Maunder, E M; Pillay, A V; Care, A D

1987-10-01

An i.v. injection of calcitriol (1,25-(OH)2D3) had no effect within 2.5 h on plasma concentrations of calbindin-D9K (vitamin D-induced calcium-binding protein; CaBP) in hypocalcaemic pigs with inherited vitamin D-dependent rickets type I or in their normocalcaemic siblings or half-siblings. Three days later the plasma concentration of CaBP had doubled in the hypocalcaemic pigs, but was unaltered in the normocalcaemic siblings and half-siblings. Following daily i.v. injections of 1,25-(OH)2D3 for a further 5 days (days 4-8) plasma concentrations of CaBP increased in both the hypocalcaemic (days 4-8) and normocalcaemic (day 8) pigs, the effect being more rapid and greater in the hypocalcaemic 1,25-(OH)2D3-deficient animals. An i.v. injection of 1,25-(OH)2D3 to pure Yucatan pigs also had no effect on plasma concentrations of CaBP within 1.5 h, but in the following 1 h there was some indication of an increase in plasma CaBP levels. In contrast to the normal pigs, insulin-induced hypoglycaemia did not lead to a peak in plasma CaBP concentrations in the hypocalcaemic pigs. There was also no change in the plasma concentrations of 1,25-(OH)2D3 associated with the peak in plasma CaBP following insulin-induced hypoglycaemia in normocalcaemic pigs. These results suggest that changes in plasma concentrations of 1,25-(OH)2D3 are not directly involved in mediating the increase in plasma CaBP which follows hypoglycaemia induced by insulin in normal pigs, although 1,25-(OH)2D3 probably plays a permissive role.

The effects of magnesium on potassium transport in ferret red cells.

PubMed Central

Flatman, P W

1988-01-01

1. The magnesium dependence of net and isotopic (using 86Rb as tracer) potassium transport was measured in fed ferret red cells. Bumetanide (0.1 mM) was used to dissect total flux into two components: bumetanide sensitive and bumetanide resistant. 2. Increasing the external magnesium concentration from zero (added) to 2 mM stimulated bumetanide-sensitive uptake by 16% but inhibited the bumetanide-resistant component by about 20%. 3. Ionophore A23187 was used to control internal magnesium concentration. A23187 was usually present in the cells during measurement of isotopic fluxes but was washed away before measurement of net fluxes. The magnesium-buffering characteristics of fed ferret red cells were assessed during these experiments. The cytoplasm acts as a high-capacity, low-affinity magnesium buffer over most of the range. Some high-affinity binding was seen in the presence of A23187 and 2 mM-EDTA. 4. A23187 itself slightly inhibits bumetanide-sensitive potassium transport. 5. Bumetanide-sensitive potassium transport is strongly dependent on the concentration of internal ionized magnesium. Transport is 35% maximal at 10(-7) M and increases up to the maximal rate at 1.3 mM. Further increase in ionized magnesium concentration to 3.5 mM has no additional effect. The curve relating activity to magnesium concentration is steepest at the physiological magnesium concentration. The effects of changing magnesium concentration are fully reversible. 6. Reduction of internal ionized magnesium concentration to 10(-7) M with A23187 and EDTA approximately doubles bumetanide-resistant potassium transport. 7. Bumetanide-sensitive fluxes occur via the sodium-potassium-chloride co-transport system under the conditions used. Results described in this paper thus suggest that internal magnesium may be an important physiological controller of sodium-potassium-chloride co-transport activity. PMID:3137332

Cadmium-induced glutathionylation of actin occurs through a ROS-independent mechanism: Implications for cytoskeletal integrity

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

Choong, Grace; Liu, Ying; Xiao, Weiqun

2013-10-15

Cadmium disrupts the actin cytoskeleton in rat mesangial cells, and we have previously shown that this involves a complex interplay involving activation of kinase signaling, protein translocation, and disruption of focal adhesions. Here we investigate the role that glutathionylation of actin plays in Cd{sup 2+}-associated cytoskeletal reorganization. Low concentrations of Cd{sup 2+} (0.5–2 μM) caused an increase in actin glutathionylation by 6 h, whereas at higher concentrations glutathionylation remained at basal levels. Although oxidation with diamide increased glutathionylation, reactive oxygen species (ROS) were not involved in the Cd{sup 2+}-dependent effect, as only Cd{sup 2+} concentrations above 2 μM were sufficientmore » to increase ROS. However, low [Cd{sup 2+}] increased total glutathione levels without affecting the ratio of reduced/oxidized glutathione, and inhibition of glutathione synthesis suppressed actin glutathionylation. Cadmium increased the activity of the enzyme glutaredoxin, which influences the equilibrium between glutathionylated and deglutathionylated proteins and thus may influence levels of glutathionylated actin. Together these observations show that cadmium-dependent effects on actin glutathionylation are affected by glutathione metabolism and not by direct effects of ROS on thiol chemistry. In vitro polymerization assays with glutathionylated actin show a decreased rate of polymerization. In contrast, immunofluorescence of cytoskeletal structure in intact cells suggests that increases in actin glutathionylation accompanying increased glutathione levels occurring under low Cd{sup 2+} exposure are protective in vivo, with cytoskeletal disruption ensuing only when higher Cd{sup 2+} concentrations increase ROS levels and prevent an increase in actin–glutathione conjugates. - Highlights: • Cadmium disrupts the actin cytoskeleton in mesangial cells. • Cadmium induces glutathionylation of actin at low concentrations. • Glutathionylation requires glutathione synthesis but is independent of ROS. • Glutathionylation is protective against cytoskeletal disruption at low cadmium.« less

QUADRICEPS LOW FREQUENCY FATIGUE AND MUSCLE PAIN ARE CONTRACTION TYPE DEPENDENT

PubMed Central

Iguchi, Masaki; Shields, Richard K.

2010-01-01

Introduction Eccentric contractions are thought to induce greater low frequency fatigue (LFF) and delayed onset muscle soreness (DOMS) than concentric contractions. This study induced a similar amount of eccentric quadriceps muscle fatigue during either a concentric or eccentric fatigue task to compare LFF and DOMS. Methods Subjects (n=22) performed concentric or eccentric fatigue tasks using 75% of the pre-fatigue maximal voluntary contraction (MVC) torque, and both tasks ended when the MVC eccentric torque decreased by 25% pre-fatigue. Results When subjects reached the failure criterion during the eccentric and concentric tasks, the concentric MVC was 78 ± 9.8% and 64 ± 8.4% of initial, respectively. LFF was greater after the concentric than the eccentric protocols (22 ± 12.4% and 15 ± 7.6% increase, respectively; p < 0.01). DOMS was over 100% greater for the eccentric protocol. Discussion These results indicate that DOMS is not dependent on the events that contribute to LFF. PMID:20544933

Real-time study of a DNA strand displacement reaction using dual polarization interferometry.

PubMed

Xu, Pingping; Huang, Fujian; Liang, Haojun

2013-03-15

A DNA strand displacement reaction on a solid-liquid interface was investigated using dual polarization interferometry. This effective analytical technique allows the real-time, simultaneous determination of the thickness, density, and mass of a biological layer. The displacement process was examined, and the changes in thickness, density, and mass were determined. Injection of the displacement DNA resulted in an increase in density and a decrease in mass and thickness, which indicated that a portion of the target DNA was displaced from the double-stranded DNA (dsDNA). The effects of the displacement DNA concentration and toehold length on the displacement efficiency were also examined. Increasing the displacement DNA concentration and the toehold length increased the changes in mass and the displacement efficiency. At the concentration of 0.2 μM, the toeholds with 4, 5, 6, and 7 bases had displacement percentages of 24.54%, 25.99%, 30.16%, and 70.41%, respectively. At displacement DNA concentrations exceeding that of the dsDNA, the displacement percentage was not concentration-dependent. Above a certain concentration, the percentage remained stable with increasing concentration. Comparison using different toehold sequences showed that the displacement efficiency increases with increasing bonding force between the base pairs. Copyright © 2012. Published by Elsevier B.V.

Mechanism of Tacrine Block at Adult Human Muscle Nicotinic Acetylcholine Receptors

PubMed Central

Prince, Richard J.; Pennington, Richard A.; Sine, Steven M.

2002-01-01

We used single-channel kinetic analysis to study the inhibitory effects of tacrine on human adult nicotinic receptors (nAChRs) transiently expressed in HEK 293 cells. Single channel recording from cell-attached patches revealed concentration- and voltage-dependent decreases in mean channel open probability produced by tacrine (IC50 4.6 μM at −70 mV, 1.6 μM at −150 mV). Two main effects of tacrine were apparent in the open- and closed-time distributions. First, the mean channel open time decreased with increasing tacrine concentration in a voltage-dependent manner, strongly suggesting that tacrine acts as an open-channel blocker. Second, tacrine produced a new class of closings whose duration increased with increasing tacrine concentration. Concentration dependence of closed-times is not predicted by sequential models of channel block, suggesting that tacrine blocks the nAChR by an unusual mechanism. To probe tacrine's mechanism of action we fitted a series of kinetic models to our data using maximum likelihood techniques. Models incorporating two tacrine binding sites in the open receptor channel gave dramatically improved fits to our data compared with the classic sequential model, which contains one site. Improved fits relative to the sequential model were also obtained with schemes incorporating a binding site in the closed channel, but only if it is assumed that the channel cannot gate with tacrine bound. Overall, the best description of our data was obtained with a model that combined two binding sites in the open channel with a single site in the closed state of the receptor. PMID:12198092

Surface roughening of undoped and in situ B-doped SiGe epitaxial layers deposited by using reduced pressure chemical vapor deposition

NASA Astrophysics Data System (ADS)

Kim, Youngmo; Park, Jiwoo; Sohn, Hyunchul

2018-01-01

Si1- x Ge x (:B) epitaxial layers were deposited by using reduced pressure chemical vapor deposition with SiH4, GeH4, and B2H6 source gases, and the dependences of the surface roughness of undoped Si1- x Ge x on the GeH4 flow rate and of Si1- x Ge x :B on the B2H6 flow rate were investigated. The root-mean-square (RMS) roughness value of the undoped Si1- x Ge x at constant thickness increased gradually with increasing Ge composition, resulting from an increase in the amplitude of the wavy surface before defect formation. At higher Ge compositions, the residual strain in Si1- x Ge x significantly decreased through the formation of defects along with an abrupt increase in the RMS roughness. The variation of the surface roughness of Si1- x Ge x :B depended on the boron (B) concentration. At low B concentrations, the RMS roughness of Si1- x Ge x remained constant regardless of Ge composition, which is similar to that of undoped Si1- x Ge x . However, at high B concentrations, the RMS roughness of Si1- x Ge x :B increased greatly due to B islanding. In addition, at very high B concentrations ( 9.9 at%), the RMS roughness of Si1- x Ge x :B decreased due to non-epitaxial growth.

Myocardium distribution of sertindole and its metabolite dehydrosertindole in guinea-pigs.

PubMed

Canal-Raffin, Mireille; Titier, Karine; Déridet, Evelyne; Martinez, Béatrice; Abouelfath, Abdelilah; Miras, Alain; Gromb, Sophie; Molimard, Mathieu; Moore, Nicholas

2006-05-01

Sertindole, like other atypical antipsychotics, has been shown to increase the action potential duration and QT interval in a concentration dependent manner, in in vitro electrophysiological studies. However, this does not always translate into increased duration of the QT interval, increased risk of torsade de pointes or sudden death in clinical practice. The reasons for these apparent discrepancies are unclear and many studies have underscored the importance of the interpretation of in vitro electrophysiological data in the context of other pharmacodynamic (e.g. cardiac ion channels target, receptor affinity) and pharmacokinetic parameters (total plasma drug concentration and drug distribution). To address the possible relevance of the concentrations used in experimental studies, the myocardium distribution of sertindole and its metabolite was determined after single and repeated intraperitoneal administration to guinea-pigs. The data suggest that the plasma concentration appears to predict the concentration in the myocardium and that the myocardium concentrations of sertindole are 3.1 times higher than plasma concentrations. Using these data, the relevance of in vitro electrophysiological studies to clinical plasma concentrations has been appraised. Copyright 2006 John Wiley & Sons, Ltd.

Electrophysiological effects of calcitonin gene-related peptide in bull-frog and guinea-pig atrial myocytes.

PubMed Central

Ono, K; Giles, W R

1991-01-01

1. Electrophysiological effects of calcitonin gene-related peptide (CGRP) on action potentials and corresponding transmembrane currents in single myocytes from bull-frog and guinea-pig atria were studied using a whole-cell voltage-clamp method. 2. CGRP at relatively low concentrations increased the height of the action potential plateau in a dose-dependent manner in both bull-frog and guinea-pig myocytes. In addition, in bull-frog cells CGRP accelerated the early phase of repolarization, thus shortening the overall duration of the action potential. In contrast, in guinea-pig myocytes CGRP prolonged the action potential duration at all concentrations that were studied. 3. Voltage-clamp measurements demonstrated that CGRP increased transmembrane calcium current (ICa) in guinea-pig myocytes without a significant change in its voltage dependence. The ED50 value for this effect on ICa was 1.28 +/- 0.55 X 10(-8) M (n = 4). The time course of the inactivation of ICa was not affected by CGRP. 4. CGRP increased the delayed rectifier K+ current (IK) at relatively low concentrations in bull-frog atria, whereas relatively high concentrations were needed to increase IK in guinea-pig myocytes. This effect was observed even after complete inhibition of ICa. 5. CGRP had no significant effect on the inwardly rectifying background K+ current, IK1, even at very high concentrations. 6. Comparison of the time course of ICa augmentation in bull-frog and guinea-pig myocytes revealed an important difference in the effect of CGRP in these two types of cells. CGRP at maximal concentrations increased ICa transiently in bull-frog myocytes, whereas this response was sustained in guinea-pig myocytes. Isoprenaline (Iso) induced sustained increase in ICa in both species. When ICa was fully activated by Iso, CGRP at high concentrations strongly inhibited ICa in the bull-frog, whereas it had little effect on ICa in guinea-pig myocytes. 7. Intracellular application of GTP gamma S (guanosine 5'-O-(3-thiotriphosphate) 10(-4) M) greatly potentiated the CGRP effect on ICa; in contrast, GDP beta S (guanosine 5'-O-(2-thiodiphosphate), 2 x 10(-3) M) partially inhibited the CGRP-induced augmentation of ICa. Taken together, these results indicate that the stimulation of ICa by CGRP is mediated by a GTP-binding protein. 8. The observed dose-dependent changes in ICa and IK in bull-frog and guinea-pig myocytes can explain the different patterns of CGRP-induced changes in action potential shape in these two myocyte preparations. PMID:1905755

Interdependence of the kinetics of NTP hydrolysis and the stability of the RecA-ssDNA complex.

PubMed

Katz, F S; Bryant, F R

2001-09-18

The ssDNA-dependent NTP hydrolysis activity of the RecA protein was examined using a series of dTn oligomers ranging in size from dT10 to dT2000 as the ssDNA effector. There were three distinct manifestations of the dTn-dependent NTP hydrolysis reaction, depending on the length of the dTn effector that was used. With longer dTn oligomers, NTP hydrolysis occurred with a turnover number of 20-25 min(-1) and the observed S0.5 value for the NTP was independent of the concentration of the dTn oligomer (DNA concentration-independent hydrolysis). With dTn oligomers of intermediate length, NTP hydrolysis still occurred with a turnover number of 20-25 min(-1), but the observed S0.5 for the NTP decreased with increasing dTn concentration until reaching a value similar to that obtained with the longer dTn oligomers (DNA concentration-dependent hydrolysis). With shorter dTn oligomers, the NTP hydrolysis activity was effectively eliminated. Although this general progression of kinetic behavior was observed for the three structurally related NTPs (dATP, ATP, and GTP), the dTn oligomer length at which DNA concentration-independent, DNA concentration-dependent, and no NTP hydrolysis was observed depended on the NTP being considered. For example, dATP (S0.5 = 35 microM) was hydrolyzed in the presence of dT20, whereas ATP (S0.5 = 70 microM) and GTP (S0.5 = 1200 microM) required at least dT50 and dT200 for hydrolysis, respectively. These results are discussed in terms of a kinetic model in which the stability of the RecA-ssDNA-NTP complex is dependent on the intrinsic S0.5 value of the NTP being hydrolyzed.

The role of external and internal mass transfer in the process of Cu2+ removal by natural mineral sorbents.

PubMed

Sljivić, M; Smiciklas, I; Plećas, I; Pejanović, S

2011-07-01

The kinetics of Cu2+ sorption on to zeolite, clay and diatomite was investigated as a function of initial metal concentrations. For consideration of the mass transfer phenomena, single resistance models based on both film and intraparticle diffusion were tested and compared. The obtained results suggested that the rate-limiting step in Cu2+ sorption strongly depended on the sorbent type, as well as on initial cation concentration. The decrease in external mass transfer coefficients with the increase in initial metal concentrations was in excellent agreement with expressions based on Sherwood and Schmidt dimensionless numbers. The internal diffusivities through zeolite particles were in the range 1.0 x 10(-11) to 1.0 x 10(-13) m2/min, depending on the Cu2+ concentration and the applied theoretical model.

Time-dependent mobility and recombination of the photoinduced charge carriers in conjugated polymer/fullerene bulk heterojunction solar cells

NASA Astrophysics Data System (ADS)

Mozer, A. J.; Dennler, G.; Sariciftci, N. S.; Westerling, M.; Pivrikas, A.; Österbacka, R.; Juška, G.

2005-07-01

Time-dependent mobility and recombination in the blend of poly[2-methoxy-5-(3,7-dimethyloctyloxy)-phenylene vinylene] (MDMO-PPV) and 1-(3-methoxycarbonyl)propyl-1-phenyl-(6,6)- C61 (PCBM) is studied simultaneously using the photoinduced charge carrier extraction by linearly increasing voltage technique. The charge carriers are photogenerated by a strongly absorbed, 3 ns laser flash, and extracted by the application of a reverse bias voltage pulse after an adjustable delay time (tdel) . It is found that the mobility of the extracted charge carriers decreases with increasing delay time, especially shortly after photoexcitation. The time-dependent mobility μ(t) is attributed to the energy relaxation of the charge carriers towards the tail states of the density of states distribution. A model based on a dispersive bimolecular recombination is formulated, which properly describes the concentration decay of the extracted charge carriers at all measured temperatures and concentrations. The calculated bimolecular recombination coefficient β(t) is also found to be time-dependent exhibiting a power law dependence as β(t)=β0t-(1-γ) with increasing slope (1-γ) with decreasing temperatures. The temperature dependence study reveals that both the mobility and recombination of the photogenerated charge carriers are thermally activated processes with activation energy in the range of 0.1 eV. Finally, the direct comparison of μ(t) and β(t) shows that the recombination of the long-lived charge carriers is controlled by diffusion.

Medication development for addictive disorders: the state of the science.

PubMed

Vocci, Frank J; Acri, Jane; Elkashef, Ahmed

2005-08-01

In 1989, the National Institute on Drug Abuse (NIDA) established its Medications Development Program. This program has concentrated on developing pharmacotherapies for opiate and cocaine dependence and, more recently, for methamphetamine and cannabis dependence. The major goals of this program are to optimize existing treatments and to expand treatment options for physicians and patients. This review will concentrate on the development of pharmacotherapies for the following substance abuse disorders: opiate, cocaine, methamphetamine, and cannabis dependence. Left untreated, opiate and stimulant dependence are responsible for significant morbidity and mortality. For example, use of illicit opiates is associated with an increased risk of hepatitis C infection, HIV infection, and other medical consequences, e.g., an overdose. The NIDA Medications Development Program has had success in developing, with pharmaceutical partners, levomethadyl acetate, buprenorphine, and buprenorphine/naloxone for opiate dependence. Moreover, several marketed medications have shown promise in reducing cocaine use. Of interest, these medications likely operate through diverse neurochemical mechanisms, suggesting that combination therapy may be a rational next step that could increase treatment gains further in cocaine-dependent patients. The Medications Development Program has also identified multiple neuronal mechanisms that are altered by chronic administration of drugs of abuse. Advances in neuroscience have identified changes in conditioned cueing, drug priming, stress-induced increases in drug intake, and reduced frontal inhibitory mechanisms as all being possible for the development of, maintenance of, and possible relapse to, addiction. Potential medications that modulate these mechanisms are highlighted.

Phosphatidylinositol 4,5-bisphosphate regulates SNARE-dependent membrane fusion.

PubMed

James, Declan J; Khodthong, Chuenchanok; Kowalchyk, Judith A; Martin, Thomas F J

2008-07-28

Phosphatidylinositol 4,5-bisphosphate (PI 4,5-P(2)) on the plasma membrane is essential for vesicle exocytosis but its role in membrane fusion has not been determined. Here, we quantify the concentration of PI 4,5-P(2) as approximately 6 mol% in the cytoplasmic leaflet of plasma membrane microdomains at sites of docked vesicles. At this concentration of PI 4,5-P(2) soluble NSF attachment protein receptor (SNARE)-dependent liposome fusion is inhibited. Inhibition by PI 4,5-P(2) likely results from its intrinsic positive curvature-promoting properties that inhibit formation of high negative curvature membrane fusion intermediates. Mutation of juxtamembrane basic residues in the plasma membrane SNARE syntaxin-1 increase inhibition by PI 4,5-P(2), suggesting that syntaxin sequesters PI 4,5-P(2) to alleviate inhibition. To define an essential rather than inhibitory role for PI 4,5-P(2), we test a PI 4,5-P(2)-binding priming factor required for vesicle exocytosis. Ca(2+)-dependent activator protein for secretion promotes increased rates of SNARE-dependent fusion that are PI 4,5-P(2) dependent. These results indicate that PI 4,5-P(2) regulates fusion both as a fusion restraint that syntaxin-1 alleviates and as an essential cofactor that recruits protein priming factors to facilitate SNARE-dependent fusion.

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

Black, Adrienne T.; Hayden, Patrick J.; Casillas, Robert P.

Sulfur mustard is a potent vesicant that induces inflammation, edema and blistering following dermal exposure. To assess molecular mechanisms mediating these responses, we analyzed the effects of the model sulfur mustard vesicant, 2-chloroethyl ethyl sulfide, on EpiDerm-FT{sup TM}, a commercially available full-thickness human skin equivalent. CEES (100-1000 {mu}M) caused a concentration-dependent increase in pyknotic nuclei and vacuolization in basal keratinocytes; at high concentrations (300-1000 {mu}M), CEES also disrupted keratin filament architecture in the stratum corneum. This was associated with time-dependent increases in expression of proliferating cell nuclear antigen, a marker of cell proliferation, and poly(ADP-ribose) polymerase (PARP) and phosphorylated histonemore » H2AX, markers of DNA damage. Concentration- and time-dependent increases in mRNA and protein expression of eicosanoid biosynthetic enzymes including COX-2, 5-lipoxygenase, microsomal PGE{sub 2} synthases, leukotriene (LT) A{sub 4} hydrolase and LTC{sub 4} synthase were observed in CEES-treated skin equivalents, as well as in antioxidant enzymes, glutathione S-transferases A1-2 (GSTA1-2), GSTA3 and GSTA4. These data demonstrate that CEES induces rapid cellular damage, cytotoxicity and inflammation in full-thickness skin equivalents. These effects are similar to human responses to vesicants in vivo and suggest that the full thickness skin equivalent is a useful in vitro model to characterize the biological effects of mustards and to develop potential therapeutics.« less

Desensitization of atriopeptin stimulated accumulation and extrusion of cyclic GMP from a kidney epithelial cell line (MDCK).

PubMed

Woods, M; Houslay, M D

1991-02-01

Atriopeptin caused dose- (EC50 ca. 2 x 10(-8) M) and time-dependent increases in the intracellular concentration of cyclic GMP in the MDCK kidney epithelial cell line; an effect potentiated by the phosphodiesterase inhibitor, IBMX. The atriopeptin-catalysed increase in cyclic GMP was transient and reached a maximum some 10-20 min after challenge of cells with atriopeptin. The basis for the transience of this increase was shown to be due to the desensitization of guanylate cyclase coupled with extrusion of cyclic GMP from the cells and the degradation of cyclic GMP by phosphodiesterase activity. Atriopeptin-catalysed extrusion of cyclic GMP was time- and dose-(EC50 ca. 1.5 x 10(-8) M) dependent and was inhibited by probenecid but not by high external cyclic GMP concentrations. The extrusion process underwent apparent desensitization as did guanylate cyclase with similar half lives (T1/2 of ca. 20 min). Desensitization was dose-dependent upon atriopeptin and did not appear to be mediated by elevated cyclic GMP concentrations as pre-incubation with 8-bromo cyclic GMP did not cause desensitization and the half-times for desensitization were similar whether or not IBMX was present. The majority of the cyclic nucleotide phosphodiesterase activity was found in the cytosol fraction of the cells and could be separated into two cyclic AMP specific forms and two cyclic GMP preferring forms.

Response of serum and red blood cell folate concentrations to folic acid supplementation depends on methylenetetrahydrofolate reductase C677T genotype: Results from a crossover trial

PubMed Central

Anderson, Cheryl A.M.; Beresford, Shirley A. A.; McLerran, Dale; Lampe, Johanna W.; Deeb, Samir; Feng, Ziding; Motulsky, Arno G.

2013-01-01

Scope By increasing blood folate concentrations, folic acid supplementation reduces risk for neural tube defect-affected pregnancies, and lowers homocysteine concentrations. We assessed response of red blood cell (RBC) and serum folate to folic acid supplementation, and examined association of response with the genetic polymorphism C677T of the methylenetetrahydrofolate NAD(P)H (MTHFR) gene. Methods and Results Randomized, controlled, crossover trial with two folic acid supplement treatment periods and a 30-week washout period. The primary outcome is blood folate (serum and RBC) concentrations. Volunteers (n=142) aged 18-69 were randomized to two of three doses (0, 200, and 400 μg) of folic acid for twelve weeks. Serum folate response depended on treatment period with significant responses to 200 μg seen only in the second treatment periods (4.4 ng/mL or 3.4 ng/mL). Additionally, serum folate increased as folic acid dose increased to 400 μg (p< 0.01) and response was greater after the washout period (8.7 ng/mL), than after a 6-week run-in (2.3 ng/mL). The differential change attributable to a daily supplement of 400 μg compared to 200 μg was 96.8 ng/mL; while the change attributable to 400 μg compared to 0 μg was 121.4. Increases in RBC folate concentrations with 400 μg occurred within MTHFR gene mutation (C677T); and in the African American group. Conclusions Serum folate concentration is responsive to modest increases in folic acid intake. Red blood cell folate increases only with higher additional doses of folic acid supplementation, and this is true for each MTHFR C677T genotype. PMID:23456769

Lipid raft components cholesterol and sphingomyelin increase H+/OH− permeability of phosphatidylcholine membranes

PubMed Central

Gensure, Rebekah H.; Zeidel, Mark L.; Hill, Warren G.

2006-01-01

H+/OH− permeation through lipid bilayers occurs at anomalously high rates and the determinants of proton flux through membranes are poorly understood. Since all life depends on proton gradients, it is important to develop a greater understanding of proton leak phenomena. We have used stopped-flow fluorimetry to probe the influence of two lipid raft components, chol (cholesterol) and SM (sphingomyelin), on H+/OH− and water permeability. Increasing the concentrations of both lipids in POPC (palmitoyl-2-oleoyl phosphatidylcholine) liposomes decreased water permeability in a concentration-dependent manner, an effect that correlated with increased lipid order. Surprisingly, proton flux was increased by increasing the concentration of chol and SM. The chol effect was complex with molar concentrations of 17.9, 33 and 45.7% giving 2.8-fold (P<0.01), 2.2-fold (P<0.001) and 5.1-fold (P<0.001) increases in H+/OH− permeability from a baseline of 2.4×10−2 cm/s. SM at 10 mole% effected a 2.8-fold increase (P<0.01), whereas 20 and 30 mole% enhanced permeability by 3.6-fold (P<0.05) and 4.1-fold respectively (P<0.05). Supplementing membranes containing chol with SM did not enhance H+/OH− permeability. Of interest was the finding that chol addition to soya-bean lipids decreased H+/OH− permeability, consistent with an earlier report [Ira and Krishnamoorthy (2001) J. Phys. Chem. B 105, 1484–1488]. We speculate that the presence of proton carriers in crude lipid extracts might contribute to this result. We conclude that (i) chol and SM specifically and independently increase rates of proton permeation in POPC bilayers, (ii) domains enriched in these lipids or domain interfaces may represent regions with high H+/OH− conductivity, (iii) H+/OH− fluxes are not governed by lipid order and (iv) chol can inhibit or promote H+/OH− permeability depending on the total lipid environment. Theories of proton permeation are discussed in the light of these results. PMID:16706750

Physical and Flavor Characteristics, Fatty Acid Profile, Antioxidant Status and Nrf2-Dependent Antioxidant Enzyme Gene Expression Changes in Young Grass Carp (Ctenopharyngodon idella) Fillets Fed Dietary Valine.

PubMed

Luo, Jian-Bo; Feng, Lin; Jiang, Wei-Dan; Liu, Yang; Wu, Pei; Jiang, Jun; Kuang, Sheng-Yao; Tang, Ling; Tang, Wu-Neng; Zhang, Yong-An; Zhou, Xiao-Qiu

2017-01-01

This study was conducted to examine the effects of dietary valine on the physical and flavor characteristics, fatty acid (FA) profile, antioxidant status and Nrf2-dependent antioxidant enzyme gene expression in the muscle of young grass carp (Ctenopharyngodon idella) fed increasing levels of valine (4.3, 8.0, 10.6, 13.1, 16.9 and 19.1 g/kg) for 8 weeks. Compared with the control group, the group fed valine showed improved physical characteristics of fish fillets (increased relative shear force, hydroxyproline, protein and lipid levels and decreased cathepsin B and L activities, as well as cooking loss, were observed). Moreover, valine improved the flavor of young grass carp fillets by increasing the amino acid (AA) concentration in fish muscle (increased aspartic acid, threonine, glutamine, cystine, methionine, leucine, tyrosine, phenylalanine, lysine, histidine, arginine and valine concentrations were observed). Additionally, optimal valine supplementation increased the potential health benefits to humans by decreasing the saturated FA (C15:0 and C16:0) concentration and increasing the unsaturated FA (monounsaturated FAs (MUFAs), such as C16:1, C18:1c+t and C20:1, and polyunsaturated FAs (PUFAs), such as C18:3n-3, C20:2 and C22:6) concentration. In addition, the reduced glutathione (GSH) content and the activities of Cu/Zn superoxide dismutase (SOD1), catalase (CAT) and Selenium-dependent glutathione peroxydase (Se-GPx) increased under valine supplementation (P < 0.05). Furthermore, the SOD1, CAT and Se-GPx mRNA levels increased with dietary valine levels, possibly due to the up-regulation of NF-E2-related factor 2 (Nrf2), target of rapamycin (TOR) and ribosomal protein S6 kinase 1 (S6K1) and the down-regulation of Kelch-like-ECH-associated protein 1 (Keap1) in muscle (P < 0.05). In conclusion, valine improved the physical and flavor characteristics, FA profile, and antioxidant status and regulated the expression of the antioxidant enzyme genes Nrf2, Keap1, TOR and S6K1 in fish fillets.

Physical and Flavor Characteristics, Fatty Acid Profile, Antioxidant Status and Nrf2-Dependent Antioxidant Enzyme Gene Expression Changes in Young Grass Carp (Ctenopharyngodon idella) Fillets Fed Dietary Valine

PubMed Central

Jiang, Wei-Dan; Liu, Yang; Wu, Pei; Jiang, Jun; Kuang, Sheng-Yao; Tang, Ling; Tang, Wu-Neng; Zhang, Yong-An; Zhou, Xiao-Qiu

2017-01-01

This study was conducted to examine the effects of dietary valine on the physical and flavor characteristics, fatty acid (FA) profile, antioxidant status and Nrf2-dependent antioxidant enzyme gene expression in the muscle of young grass carp (Ctenopharyngodon idella) fed increasing levels of valine (4.3, 8.0, 10.6, 13.1, 16.9 and 19.1 g/kg) for 8 weeks. Compared with the control group, the group fed valine showed improved physical characteristics of fish fillets (increased relative shear force, hydroxyproline, protein and lipid levels and decreased cathepsin B and L activities, as well as cooking loss, were observed). Moreover, valine improved the flavor of young grass carp fillets by increasing the amino acid (AA) concentration in fish muscle (increased aspartic acid, threonine, glutamine, cystine, methionine, leucine, tyrosine, phenylalanine, lysine, histidine, arginine and valine concentrations were observed). Additionally, optimal valine supplementation increased the potential health benefits to humans by decreasing the saturated FA (C15:0 and C16:0) concentration and increasing the unsaturated FA (monounsaturated FAs (MUFAs), such as C16:1, C18:1c+t and C20:1, and polyunsaturated FAs (PUFAs), such as C18:3n-3, C20:2 and C22:6) concentration. In addition, the reduced glutathione (GSH) content and the activities of Cu/Zn superoxide dismutase (SOD1), catalase (CAT) and Selenium-dependent glutathione peroxydase (Se-GPx) increased under valine supplementation (P < 0.05). Furthermore, the SOD1, CAT and Se-GPx mRNA levels increased with dietary valine levels, possibly due to the up-regulation of NF-E2-related factor 2 (Nrf2), target of rapamycin (TOR) and ribosomal protein S6 kinase 1 (S6K1) and the down-regulation of Kelch-like-ECH-associated protein 1 (Keap1) in muscle (P < 0.05). In conclusion, valine improved the physical and flavor characteristics, FA profile, and antioxidant status and regulated the expression of the antioxidant enzyme genes Nrf2, Keap1, TOR and S6K1 in fish fillets. PMID:28118364

Nitric oxide affects IL-6 expression in human peripheral blood mononuclear cells involving cGMP-dependent modulation of NF-κB activity.

PubMed

Siednienko, Jakub; Nowak, Joanna; Moynagh, Paul N; Gorczyca, Wojciech A

2011-06-01

Interleukin 6 (IL-6) and nitric oxide (NO) are important mediators of the inflammatory response. We report that in human peripheral blood mononuclear cells (PBMCs), NO exerts a biphasic effect on the expression of IL-6. Using sodium nitroprusside (SNP) and S-nitrosoglutathione (GSNO) as NO-donating compounds, we observed that both mRNA and protein levels of IL-6 increased at lower (≤10μM) and decreased at higher (>100μM) concentrations of NO donors. Changes in the expression of IL-6 correlated with changes in the activity of NF-κB, which increased at lower and decreased at higher concentrations of both NO donors as shown by the electrophoretic mobility shift assay (EMSA). The effects of NO on NF-κB activity were cGMP-dependent because they were reversed in the presence of ODQ, the inhibitor of soluble guanylyl cyclase (sGC), and KT5823, the inhibitor of cGMP-dependent protein kinase (PKG). Moreover, the membrane permeable analog of cGMP (8-Br-cGMP) mimicked the effect of the NO donors. These observations show that NO, depending on its concentration, may act in human PBMCs as a stimulator of IL-6 expression involving the sGC/cGMP/PKG pathway. Copyright © 2011 Elsevier Ltd. All rights reserved.

Effects of phosphoramidon on endothelin-1 and big endothelin-1 production in human aortic endothelial cells.

PubMed

Matsumura, Y; Tsukahara, Y; Kojima, T; Murata, S; Murakami, A; Takada, K; Takaoka, M; Morimoto, S

1995-03-01

Using cultured human aortic endothelial cells, we examined the effects of phosphoramidon, an endothelin converting enzyme (ECE) inhibitor, on the release of endogenous endothelin-1 (ET-1) and big endothelin-1 (big ET-1), and on the generation of ET-1 from exogenously applied big ET-1. Phosphoramidon, at concentrations of 10(-6) to 2 x 10(-4) M, caused a biphasic alteration of the ET-1 release, i.e., at lower concentrations of the drug, there were slight but unexpected increases of the release, whereas higher concentrations led to a decrease which is due to the drug-induced inhibition of ECE. The former effect appears to be based on the inhibition of ET-1 degradation by neutral endopeptidase 24.11 (NEP), since kelatorphan, a specific NEP inhibitor, produced a similar increasing effect on ET-1 release. Phosphoramidon enhanced the big ET-1 release from the cells in a concentration-dependent manner. When high concentrations of phosphoramidon were added, there was a dramatic increase in the release of big ET-1, which cannot be explained only by the drug-induced inhibition of ECE. This increase in big ET-1 release appeared to be partly due to a transient stimulation of the expression of prepro ET-1 mRNA. The amount of ET-1 generated from exogenously applied big ET-1 was markedly decreased by phosphoramidon in a concentration-dependent manner. In a similar fashion, phosphoramidon markedly inhibited ECE activity of the membrane fraction of cultured cells. Thus, ET-1 generation from exogenously applied big ET-1 reflects the functional phosphoramidon-sensitive ECE activities in human aortic endothelial cells.(ABSTRACT TRUNCATED AT 250 WORDS)

The Seismic Velocity In Gas-charged Magma

NASA Astrophysics Data System (ADS)

Sturton, S.; Neuberg, J. W.

2001-12-01

Long-period and hybrid events, seen at the Soufrière Hills Volcano, Montserrat, show dominant low frequency content suggesting the seismic wavefield is formed as a result of interface waves at the boundary between a fluid and a solid medium. This wavefield will depend on the impedance contrast between the two media and therefore the difference in seismic velocity. For a gas-charged magma, increasing pressure with depth reduces the volume of gas exsolved, increasing the seismic velocity with depth in the conduit. The seismic radiation pattern along the conduit can then be modelled. Where single events merge into tremor, gliding lines can sometimes be seen in the spectra and indicate either changes in the seismic parameters with time or varying triggering rates of single events.The differential equation describing the time dependence of bubble growth by diffusion is solved numerically for a stationary magma column undergoing a decompression event. The volume of gas is depth dependent and increases with time as the bubbles grow and expand. It is used to calculate the depth and time dependence of the density, pressure and seismic velocity. The effect of different viscosities associated with different magma types and concentration of water in the melt on the rate of bubble growth is explored. Crystal growth, which increases the concentration of water in the melt, affects the amount of gas that can be exsolved.

Evaporation-induced self-assembly of quantum dots-based concentric rings on polymer-based nanocomposite films.

PubMed

Zhang, Shaofu; Luan, Weiling; Zhong, Qixin; Yin, Shaofeng; Yang, Fuqian

2016-10-12

The "ball-on-film" template is used to construct concentric rings on the surface of PMMA-QDs (polymethyl methacrylate - quantum dots) nanocomposite films via the evaporation of pure chloroform droplets, which are confined by a steel ball. The concentric rings consist of QDs, as revealed by the fluorescence images of the concentric rings. The photoluminescence intensity of the concentric rings increases with the increase of the distance to the ball center, suggesting that the amount of QDs accumulated around the contact line at individual stick state increases with the increase of the distance to the ball center. Both the wavelength and cross-sectional area (width) of the concentric rings increase approximately linearly with increasing distance to the ball center, independent of the ball size, the film thickness and the QDs concentration. For the PMMA-QDs nanocomposite films prepared from the same QDs concentration in chloroform, the thicker the PMMA-QDs nanocomposite film, the larger the wavelength for the same distance to the ball center. The effect of confinement of two steel balls on the surface patterns over the PMMA-QDs nanocomposite films is studied via a template of "two spheres on film". Symmetric surface patterns are formed. There exist two types of featureless zone between the two balls, depending on the distance between the two balls: one is the inner featureless zone and the other is the outer featureless zone. The size of both featureless zones increases with the increase of the ball distance.

Absorption Spectroscopy Analysis of Calcium-Phosphate Glasses Highly Doped with Monovalent Copper.

PubMed

Jiménez, José A

2016-06-03

CaO-P2 O5 glasses with high concentrations of monovalent copper ions were prepared by a simple melt-quench method through CuO and SnO co-doping. Spectroscopic characterization was carried out by optical absorption with the aim of analyzing the effects of Cu(+) ions on the optical band-gap energies, which were estimated on the basis of indirect-allowed transitions. The copper(I) content is estimated in the CuO/SnO-containing glasses after the assessment of the concentration dependence of Cu(2+) absorption in the visible region for CuO singly doped glasses. An exponential dependence of the change in optical band gaps (relative to the host) with Cu(+) concentration is inferred up to about 10 mol %. However, the entire range is divided into two distinct linear regions that are characterized by different rates of change with respect to concentration: 1) below 5 mol %, where the linear dependence presents a relatively high magnitude of the slope; and 2) from 5-10 mol %, where a lower magnitude of the slope is manifested. With increasing concentration, the mean Cu(+) -Cu(+) interionic distance decreases, thereby decreasing the sensitivity of monovalent copper for light absorption. The decrease in optical band-gap energies is ultimately shown to follow a linear dependence with the interionic distance, suggesting the potential of the approach to gauge the concentration of monovalent copper straightforwardly in amorphous hosts. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hair Mercury Concentrations in Western Hudson Bay Polar Bear Family Groups.

PubMed

Bechshoft, Thea; Derocher, Andrew E; Richardson, Evan; Lunn, Nicholas J; St Louis, Vincent L

2016-05-17

Methylmercury is one of the more toxic forms of mercury (Hg), the biomagnification of which is prevalent in the Arctic where apex predators such as polar bears (Ursus maritimus) can carry high loads. The maternal transfer of contaminants to offspring is a concern, as offspring may be particularly sensitive to the effects of environmental pollutants during early development. However, few studies of polar bears report on Hg in dependent young. We examined hair total Hg (THg) concentrations in 24 polar bear family groups in western Hudson Bay: mother, cub-of-the-year (COY), yearling, and 2 year old. THg concentrations increased with bear age, with COYs having lower concentrations than other offspring groups (p ≤ 0.008). Using AICc-based regression models, we found maternal THg to be positively related to body condition and litter size, while overall offspring THg was positively related to maternal body condition in addition to being dependent on the sex and age of the offspring. COY THg concentrations were positively related to maternal THg while also depending on the sex of the offspring. Considering our results, future studies in polar bear ecotoxicology are encouraged to include offspring of different ages and sexes.

Association between Air Pollution and Hemoptysis

PubMed Central

Garcia-Olive, Ignasi; Radua, Joaquim; Fiz, Jose Antonio; Sanz-Santos, Jose; Ruiz-Manzano, Juan

2016-01-01

Background. The relationship between air pollution and exacerbation of respiratory diseases is well established. Nevertheless, its association with hemoptysis has been poorly investigated. This paper describes the relationship of air pollutants with severe hemoptysis. Methods. All consecutive subjects with severe hemoptysis during a 5-year period were included. The relationship between the contamination measurements and the frequency of embolizations was analyzed using Poisson regressions. In these regressions, the dependent variable was the monthly number of embolizations in a given month and the independent variable was either the concentration of an air contaminant during the same month, the concentration of the air contaminant during the previous month, or the difference between the two. Results. A higher total number of embolizations per month were observed over the months with increases in the concentration of NO. The number of embolizations was 2.0 in the 33 months with no increases in the concentration of NO, 2.1 in the 12 months with small increases, 2.2 in the 5 months with moderate increases, 2.5 in the 4 months with large increases, and 4.0 in the 5 months with very large increases. Conclusion. There is association between hemoptysis and increases in the concentration of atmospheric NO in Badalona (Spain). PMID:27445569

Statistical theory of diffusion in concentrated bcc and fcc alloys and concentration dependencies of diffusion coefficients in bcc alloys FeCu, FeMn, FeNi, and FeCr

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

Vaks, V. G.; Khromov, K. Yu., E-mail: khromov-ky@nrcki.ru; Pankratov, I. R.

2016-07-15

The statistical theory of diffusion in concentrated bcc and fcc alloys with arbitrary pairwise interatomic interactions based on the master equation approach is developed. Vacancy–atom correlations are described using both the second-shell-jump and the nearest-neighbor-jump approximations which are shown to be usually sufficiently accurate. General expressions for Onsager coefficients in terms of microscopic interatomic interactions and some statistical averages are given. Both the analytical kinetic mean-field and the Monte Carlo methods for finding these averages are described. The theory developed is used to describe sharp concentration dependencies of diffusion coefficients in several iron-based alloy systems. For the bcc alloys FeCu,more » FeMn, and FeNi, we predict the notable increase of the iron self-diffusion coefficient with solute concentration c, up to several times, even though values of c possible for these alloys do not exceed some percent. For the bcc alloys FeCr at high temperatures T ≳ 1400 K, we show that the very strong and peculiar concentration dependencies of both tracer and chemical diffusion coefficients observed in these alloys can be naturally explained by the theory, without invoking exotic models discussed earlier.« less

Antitumor effect of the selective COX-2 inhibitor celecoxib on endometrial adenocarcinoma in vitro and in vivo

PubMed Central

XIAO, YITAO; TENG, YINCHENG; ZHANG, RUI; LUO, LAIMIN

2012-01-01

The aim of this study was to investigate the antitumor effect of the selective cyclooxygenase-2 (COX-2) inhibitor celecoxib on endometrial adenocarcinoma in mice. Various amounts of celecoxib were added to HEC-1B cells in vitro for different durations. Cell cycle and apoptosis were analyzed using flow cytometry. HEC-1B cytostasis, invasiveness and COX-2 expression were examined by MTT, transwell cabin and western blot assays, respectively. An in vivo human endometrial adenocarcinoma model was established in BALB/c nude mice using HEC-1B cells. For two weeks, the celecoxib groups were treated with celecoxib 2 or 4 mg/day via oral administration and the control group was treated with saline. Tumor volume, growth curves and the inhibition rate (IR) were recorded. COX-2 expression levels and microvessel density (MVD) were investigated using an immunohistochemical technique. In the celecoxib groups, cell proliferation was significantly inhibited in a concentration- and time-dependent manner. The proportion of cells in the G0/G1 phase increased within 24 h after the addition of celecoxib whereas those in the S and G2/M phases decreased with an increasing apoptosis peak (sub-G1) and apoptosis rate. The microporous Matrigel-coated polycarbonate membrane of the Transwell cabin was traversable for the HEC-1B cells. The invasiveness was attenuated when the celecoxib concentration was increased. The tumor growth was also greatly inhibited when the celecoxib concentration was increased. The tumor IRs were 32.4 and 48.6% following treatment with 2 and 4 mg/day celecoxib, respectively. COX-2 was mainly expressed in the cytoplasm of the tumor cells. In the celecoxib groups, the COX-2 expression levels were concentration-dependent. The COX-2 expression level and MVD decreased when the celecoxib concentration was increased. The results of dependability analysis revealed that the COX-2 expression level was positively correlated with MVD (r=0.921; P<0.01). The antitumor effect of celecoxib on endometrial adenocarcinoma in nude mice may be related to the inhibition of COX-2 expression and microangiogenesis. PMID:23226798

CMOS image sensors as an efficient platform for glucose monitoring.

PubMed

Devadhasan, Jasmine Pramila; Kim, Sanghyo; Choi, Cheol Soo

2013-10-07

Complementary metal oxide semiconductor (CMOS) image sensors have been used previously in the analysis of biological samples. In the present study, a CMOS image sensor was used to monitor the concentration of oxidized mouse plasma glucose (86-322 mg dL(-1)) based on photon count variation. Measurement of the concentration of oxidized glucose was dependent on changes in color intensity; color intensity increased with increasing glucose concentration. The high color density of glucose highly prevented photons from passing through the polydimethylsiloxane (PDMS) chip, which suggests that the photon count was altered by color intensity. Photons were detected by a photodiode in the CMOS image sensor and converted to digital numbers by an analog to digital converter (ADC). Additionally, UV-spectral analysis and time-dependent photon analysis proved the efficiency of the detection system. This simple, effective, and consistent method for glucose measurement shows that CMOS image sensors are efficient devices for monitoring glucose in point-of-care applications.

Glymphatic clearance controls state-dependent changes in brain lactate concentration.

PubMed

Lundgaard, Iben; Lu, Minh Lon; Yang, Ezra; Peng, Weiguo; Mestre, Humberto; Hitomi, Emi; Deane, Rashid; Nedergaard, Maiken

2017-06-01

Brain lactate concentration is higher during wakefulness than in sleep. However, it is unknown why arousal is linked to an increase in brain lactate and why lactate declines within minutes of sleep. Here, we show that the glymphatic system is responsible for state-dependent changes in brain lactate concentration. Suppression of glymphatic function via acetazolamide treatment, cisterna magna puncture, aquaporin 4 deletion, or changes in body position reduced the decline in brain lactate normally observed when awake mice transition into sleep or anesthesia. Concurrently, the same manipulations diminished accumulation of lactate in cervical, but not in inguinal lymph nodes when mice were anesthetized. Thus, our study suggests that brain lactate is an excellent biomarker of the sleep-wake cycle and increases further during sleep deprivation, because brain lactate is inversely correlated with glymphatic-lymphatic clearance. This analysis provides fundamental new insight into brain energy metabolism by demonstrating that glucose that is not fully oxidized can be exported as lactate via glymphatic-lymphatic fluid transport.

Glymphatic clearance controls state-dependent changes in brain lactate concentration

PubMed Central

Lu, Minh Lon; Yang, Ezra; Peng, Weiguo; Mestre, Humberto; Hitomi, Emi; Deane, Rashid; Nedergaard, Maiken

2016-01-01

Brain lactate concentration is higher during wakefulness than in sleep. However, it is unknown why arousal is linked to an increase in brain lactate and why lactate declines within minutes of sleep. Here, we show that the glymphatic system is responsible for state-dependent changes in brain lactate concentration. Suppression of glymphatic function via acetazolamide treatment, cisterna magna puncture, aquaporin 4 deletion, or changes in body position reduced the decline in brain lactate normally observed when awake mice transition into sleep or anesthesia. Concurrently, the same manipulations diminished accumulation of lactate in cervical, but not in inguinal lymph nodes when mice were anesthetized. Thus, our study suggests that brain lactate is an excellent biomarker of the sleep–wake cycle and increases further during sleep deprivation, because brain lactate is inversely correlated with glymphatic-lymphatic clearance. This analysis provides fundamental new insight into brain energy metabolism by demonstrating that glucose that is not fully oxidized can be exported as lactate via glymphatic-lymphatic fluid transport. PMID:27481936

The effects of ABCG5/G8 polymorphisms on plasma HDL cholesterol concentrations depend on smoking habit in the Boston Puerto Rican Health Study

USDA-ARS?s Scientific Manuscript database

Background-Low high-density lipoprotein cholesterol (HDL-C) is associated with an increased risk for atherosclerosis and concentrations are modulated by genetic and environmental factors such as smoking. Objective- To assess whether the association of common single nucleotide polymorphisms (SNPs...

Regulation of ATP production: dependence on calcium concentration and respiratory state.

PubMed

Fink, Brian D; Bai, Fan; Yu, Liping; Sivitz, William I

2017-08-01

Nanomolar free calcium enhances oxidative phosphorylation. However, the effects over a broad concentration range, at different respiratory states, or on specific energy substrates are less clear. We examined the action of varying [Ca 2+ ] over respiratory states ranging 4 to 3 on skeletal muscle mitochondrial respiration, potential, ATP production, and H 2 O 2 production using ADP recycling to clamp external [ADP]. Calcium at 450 nM enhanced respiration in mitochondria energized by the complex I substrates, glutamate/malate (but not succinate), at [ADP] of 4-256 µM, but more substantially at intermediate respiratory states and not at all at state 4. Using varied [Ca 2+ ], we found that the stimulatory effects on respiration and ATP production were most prominent at nanomolar concentrations, but inhibitory at 10 µM or higher. ATP production decreased more than respiration at 10 µM calcium. However, potential continued to increase up to 10 µM; suggesting a calcium-induced inability to utilize potential for phosphorylation independent of opening of the mitochondrial permeability transition pore (MTP). This effect of 10 µM calcium was confirmed by direct determination of ATP production over a range of potential created by differing substrate concentrations. Consistent with past reports, nanomolar [Ca 2+ ] had a stimulatory effect on utilization of potential for phosphorylation. Increasing [Ca 2+ ] was positively and continuously associated with H 2 O 2 production. In summary, the stimulatory effect of calcium on mitochondrial function is substrate dependent and most prominent over intermediate respiratory states. Calcium stimulates or inhibits utilization of potential for phosphorylation dependent on concentration with inhibition at higher concentration independent of MTP opening.

Electroencephalographic patterns of lithium poisoning: a study of the effect/concentration relationships in the rat.

PubMed

Hanak, Anne-Sophie; Malissin, Isabelle; Poupon, Joël; Risède, Patricia; Chevillard, Lucie; Mégarbane, Bruno

2017-03-01

Lithium overdose may result in encephalopathy and electroencephalographic abnormalities. Three poisoning patterns have been identified based on the ingested dose, previous treatment duration and renal function. Whether the severity of lithium-induced encephalopathy depends on the poisoning pattern has not been established. We designed a rat study to investigate lithium-induced encephalopathy and correlate its severity to plasma, erythrocyte, cerebrospinal fluid and brain lithium concentrations previously determined in rat models mimicking human poisoning patterns. Lithium-induced encephalopathy was assessed and scored using continuous electroencephalography. We demonstrated that lithium overdose was consistently responsible for encephalopathy, the severity of which depended on the poisoning pattern. Acutely poisoned rats developed rapid-onset encephalopathy which reached a maximal grade of 2/5 at 6 h and disappeared at 24 h post-injection. Acute-on-chronically poisoned rats developed persistent and slightly fluctuating encephalopathy which reached a maximal grade of 3/5. Chronically poisoned rats developed rapid-onset but gradually increasing life-threatening encephalopathy which reached a maximal grade of 4/5. None of the acutely, 20% of the acute-on-chronically and 57% of the chronically lithium-poisoned rats developed seizures. The relationships between encephalopathy severity and lithium concentrations fitted a sigmoidal E max model based on cerebrospinal fluid concentrations in acute poisoning and brain concentrations in acute-on-chronic poisoning. In chronic poisoning, worsening of encephalopathy paralleled the increase in plasma lithium concentrations. The severity of lithium-induced encephalopathy is dependent on the poisoning pattern, which was previously shown to determine lithium accumulation in the brain. Our data support the proposition that electroencephalography is a sensitive tool for scoring lithium-related neurotoxicity. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Sonophoresis Using Ultrasound Contrast Agents: Dependence on Concentration.

PubMed

Park, Donghee; Song, Gillsoo; Jo, Yongjun; Won, Jongho; Son, Taeyoon; Cha, Ohrum; Kim, Jinho; Jung, Byungjo; Park, Hyunjin; Kim, Chul-Woo; Seo, Jongbum

2016-01-01

Sonophoresis can increase skin permeability to various drugs in transdermal drug delivery. Cavitation is recognized as the predominant mechanism of sonophoresis. Recently, a new logical approach to enhance the efficiency of transdermal drug delivery was tried. It is to utilize the engineered microbubble and its resonant frequency for increase of cavitation activity. Actively-induced cavitation with low-intensity ultrasound (less than ~1 MPa) causes disordering of the lipid bilayers and the formation of aqueous channels by stable cavitation which indicates a continuous oscillation of bubbles. Furthermore, the mutual interactions of microbubble determined by concentration of added bubble are also thought to be an important factor for activity of stable cavitation, even in different characteristics of drug. In the present study, we addressed the dependence of ultrasound contrast agent concentration using two types of drug on the efficiency of transdermal drug delivery. Two types of experiment were designed to quantitatively evaluate the efficiency of transdermal drug delivery according to ultrasound contrast agent concentration. First, an experiment of optical clearing using a tissue optical clearing agent was designed to assess the efficiency of sonophoresis with ultrasound contrast agents. Second, a Franz diffusion cell with ferulic acid was used to quantitatively determine the amount of drug delivered to the skin sample by sonophoresis with ultrasound contrast agents. The maximum enhancement ratio of sonophoresis with a concentration of 1:1,000 was approximately 3.1 times greater than that in the ultrasound group without ultrasound contrast agent and approximately 7.5 times greater than that in the control group. These results support our hypothesis that sonophoresis becomes more effective in transdermal drug delivery due to the presence of engineered bubbles, and that the efficiency of transdermal drug delivery using sonophoresis with microbubbles depends on the concentration of microbubbles in case stable cavitation is predominant.

Effects of T-2 Toxin on Pacific White Shrimp Litopenaeus vannamei: Growth, and Antioxidant Defenses and Capacity and Histopathology in the Hepatopancreas.

PubMed

Deng, Yijia; Wang, Yaling; Zhang, Xiaodi; Sun, Lijun; Wu, Chaojin; Shi, Qi; Wang, Rundong; Sun, Xiaodong; Bi, Siyuan; Gooneratne, Ravi

2017-03-01

Modified-masked T-2 toxin (mT-2) formed during metabolism in edible aquatic animals may go undetected by traditional analytical methods, thereby underestimating T-2 toxicity. The effects of T-2 on growth and antioxidant capacity and histopathological changes in the hepatopancreas were studied in Pacific white shrimp Litopenaeus vannamei exposed for 20 d to 0, 0.5, 1.2, 2.4, 4.8, and 12.2 mg/kg of T-2 in their feed. The concentration of mT-2 in the hepatopancreas was detected by liquid chromatography-tandem mass spectrophotometry before and after trifluoroacetic acid (TFA) treatment that converted mT-2 to free T-2. A dose-dependent increase in mT-2 concentration was observed in the hepatopancreas. Dietary exposure to T-2 significantly decreased (P < 0.05) shrimp growth and survival rate compared with the controls. The malondialdehyde (MDA) concentration was significantly increased in shrimp exposed to feed with ≥2.4 mg/kg T-2 (P < 0.05). The antioxidant enzymes, superoxide dismutase (SOD) and glutathione peroxidase (GPx), total antioxidant capacity (T-AOC), and also glutathione (GSH) content increased in shrimp dosed with 2.4-4.8 mg/kg T-2 but declined at the highest dose (12.2 mg/kg), probably indicating an inability to cope with high concentrations of reactive oxygen species (ROS) as evident from a marked increase in MDA (P < 0.05) culminating in cellular toxicity. Histopathological changes in the hepatopancreas were dose dependent, with cell autophagy evident at the highest exposure dose. This is the first report in shrimp of a dose-dependent increase in ROS, SOD enzyme activity, and T-AOC at low T-2 exposures, and associated histopathological changes in the hepatopancreas, in response to dietary T-2. Received January 26, 2016; accepted October 9, 2016.

Electrical conductivity of cobalt doped La 0.8Sr 0.2Ga 0.8Mg 0.2O 3- δ

NASA Astrophysics Data System (ADS)

Wang, Shizhong; Wu, Lingli; Liang, Ying

La 0.8Sr 0.2Ga 0.8Mg 0.2O 3- δ (LSGM8282), La 0.8Sr 0.2Ga 0.8Mg 0.15Co 0.05O 3- δ (LSGMC5) and La 0.8Sr 0.2Ga 0.8Mg 0.115Co 0.085O 3- δ (LSGMC8.5) were prepared using a conventional solid-state reaction. Electrical conductivities and electronic conductivities of the samples were measured using four-probe impedance spectrometry, four-probe dc polarization and Hebb-Wagner polarization within the temperature range of 973-1173 K. The electrical conductivities in LSGMC5 and LSGMC8.5 increased with decreasing oxygen partial pressures especially in the high (>10 -5 atm) and low oxygen partial pressure regions (<10 -15 atm). However, the electrical conductivity in LSGM8282 had no dependency on the oxygen partial pressure. At temperatures higher than 1073 K, PO2 dependencies of the free electron conductivities in LSGM8282, LSGMC5 and LSGMC8.5 were about -1/4, and PO2 dependencies of the electron hole conductivities were about 0.25, 0.12 and 0.07, respectively. Oxygen ion conductivities in LSGMC5 and LSGMC8.5 increased with decreasing oxygen partial pressures especially in the high and low oxygen partial pressure regions, which was due to the increase in the concentration of oxygen vacancies. The change in the concentration of oxygen vacancies and the valence of cobalt with oxygen partial pressure were determined using a thermo-gravimetric technique. Both the electronic conductivity and oxygen ion conductivity in cobalt doped lanthanum gallate samples increased with increasing concentration of cobalt, suggesting that the concentration of cobalt should be optimized carefully to maintain a high electrical conductivity and close to 1 oxygen ion transference number.

Charge carrier dynamics and relaxation in (polyethylene oxide-lithium-salt)-based polymer electrolyte containing 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide as ionic liquid

NASA Astrophysics Data System (ADS)

Karmakar, A.; Ghosh, A.

2011-11-01

In this paper we report the dynamics of charge carriers and relaxation in polymer electrolytes based on polyethylene oxide (PEO), lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) and 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (BMPTFSI) ionic liquid prepared by solution cast technique. It has been observed that the incorporation of BMPTFSI into PEO-LiTFSI electrolyte is an effective way for increasing the amorphous phase to a large extent. It has also been observed that both the glass transition and melting temperatures decrease with the increase of BMPTFSI concentration. The ionic conductivity of these polymer electrolytes increases with the increase of BMPTFSI concentration. The highest ionic conductivity obtained at 25 °C is ˜3×10-4 S cm-1 for the electrolyte containing 60 wt % BMPTFSI and ethylene oxide (EO)/Li ratio of 20. The temperature dependence of the dc conductivity and the hopping frequency show Vogel-Tamman-Fulcher type behavior indicating a strong coupling between the ionic and the polymer chain segmental motions. The frequency dependence of the ac conductivity exhibits a power law with an exponent n which decreases with the increase of temperature. The scaling of the ac conductivity indicates that relaxation dynamics of charge carriers follows a common mechanism for all temperatures and BMPTFSI concentrations. We have also presented the electric modulus data which have been analyzed in the framework of a Havriliak-Negami equation and the shape parameters obtained by the analysis show slight temperature dependence, but change sharply with BMPTFSI concentration. The stretched exponent β obtained from Kohlrausch-Williams-Watts fit to the modulus data is much lower than unity signifying that the relaxation is highly nonexponential. The decay function obtained from analysis of experimental modulus data is highly asymmetric with time.

In vivo evidence for the reversible action of the monoamine oxidase inhibitor brofaromine on 5-hydroxytryptamine release in rat brain.

PubMed

Bel, N; Artigas, F

1995-05-01

We have used intracerebral microdialysis to examine the reversibility of the action of brofaromine, a selective inhibitor of monoamine oxidase-A (MAO, E.C. 1.4.3.4.), on 5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) output in rat frontal cortex. Brofaromine significantly increased the 5-HT output to about 200% of basal values 4 h after the s.c. administration of 10 and 30 mg/kg (but not 3 mg/kg) and reduced the concentration of 5-HIAA in the dialysate dose-dependently (61%, 53% and 41% of basal value with doses of 3, 10 and 30 mg/kg, respectively). At this time, cortical 5-HT concentration was increased and cortical 5-HIAA concentration was decreased in a dose-dependent manner. Treatment of rats with 10 mg/kg brofaromine plus 2.5 mg/kg of the irreversible MAO-B inhibitor L-deprenyl increased the concentration of 5-HT in the dialysate more than did brofaromine alone (503% vs 206% of the basal value, 4h after administration). Similarly, clorgyline (5 mg/kg) plus L-deprenyl (2.5 mg/kg) increased the concentration of 5-HT in the dialysate to 461% of the control value. This indicates that the concurrent inhibition of both types of MAO increases 5-HT output more than the selective blockade of either enzyme subtype. We have used this characteristic to examine, in vivo, the reversibility of the interaction of brofaromine with MAO-A. The output of 5-HT and 5-HIAA was examined 19-21 h after treatment with L-deprenyl plus clorgyline or L-deprenyl plus brofaromine.(ABSTRACT TRUNCATED AT 250 WORDS)

Trends in the suspended-sediment yields of coastal rivers of northern California, 1955–2010

USGS Publications Warehouse

Warrick, J.A.; Madej, Mary Ann; Goñi, M. A.; Wheatcroft, R.A.

2013-01-01

Time-dependencies of suspended-sediment discharge from six coastal watersheds of northern California – Smith River, Klamath River, Trinity River, Redwood Creek, Mad River, and Eel River – were evaluated using monitoring data from 1955 to 2010. Suspended-sediment concentrations revealed time-dependent hysteresis and multi-year trends. The multi-year trends had two primary patterns relative to river discharge: (i) increases in concentration resulting from both land clearing from logging and the flood of record during December 1964 (water year 1965), and (ii) continual decreases in concentration during the decades following this flood. Data from the Eel River revealed that changes in suspended-sediment concentrations occurred for all grain-size fractions, but were most pronounced for the sand fraction. Because of these changes, the use of bulk discharge-concentration relationships (i.e., “sediment rating curves”) without time-dependencies in these relationships resulted in substantial errors in sediment load estimates, including 2.5-fold over-prediction of Eel River sediment loads since 1979. We conclude that sediment discharge and sediment discharge relationships (such as sediment rating curves) from these coastal rivers have varied substantially with time in response to land use and climate. Thus, the use of historical river sediment data and sediment rating curves without considerations for time-dependent trends may result in significant errors in sediment yield estimates from the globally-important steep, small watersheds.

Effect of overcharge on Li(Ni0.5Mn0.3Co0.2)O2/Graphite lithium ion cells with poly(vinylidene fluoride) binder. I - Microstructural changes in the anode

NASA Astrophysics Data System (ADS)

Dietz Rago, Nancy; Bareño, Javier; Li, Jianlin; Du, Zhijia; Wood, David L.; Steele, Leigh Anna; Lamb, Joshua; Spangler, Scott; Grosso, Christopher; Fenton, Kyle; Bloom, Ira

2018-05-01

Cells based on NMC/graphite, containing poly(vinylidene difluoride) (PVDF) binders in the positive and negative electrodes, were systematically overcharged to 100, 120, 140, 160, 180, and 250% state-of-charge (SOC). At 250% SOC the cell vented. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) of the anodes showed several state-of-overcharge-dependent trends. Starting at 120% SOC, dendrites appeared and increased in concentration as the SOC increased. Dendrite morphology appeared to be dependent on whether the active material was on the "dull" or "shiny" side of the copper collector. Significantly more delamination of the active material from the collector was seen on the "shiny" side of the collector particularly at 180 and 250% SOC. Transition metals were detected at 120% SOC and increased in concentration as the SOC increased. There was considerable spatial heterogeneity in the microstructures across each laminate with several regions displaying complex layered structures.

Determination of ethane, pentane and isoprene in exhaled air--effects of breath-holding, flow rate and purified air.

PubMed

Lärstad, M A E; Torén, K; Bake, B; Olin, A-C

2007-01-01

Exhaled ethane, pentane and isoprene have been proposed as biomarkers of oxidative stress. The objectives were to explore whether ethane, pentane and isoprene are produced within the airways and to explore the effect of different sampling parameters on analyte concentrations. The flow dependency of the analyte concentrations, the concentrations in dead-space and alveolar air after breath-holding and the influence of inhaling purified air on analyte concentrations were investigated. The analytical method involved thermal desorption from sorbent tubes and gas chromatography. The studied group comprised 13 subjects with clinically stable asthma and 14 healthy controls. Ethane concentrations decreased slightly, but significantly, at higher flow rates in subjects with asthma (P = 0.0063) but not in healthy controls. Pentane levels were increased at higher flow rates both in healthy and asthmatic subjects (P = 0.022 and 0.0063 respectively). Isoprene levels were increased at higher flow rates, but only significantly in healthy subjects (P = 0.0034). After breath-holding, no significant changes in ethane levels were observed. Pentane and isoprene levels increased significantly after 20 s of breath-holding. Inhalation of purified air before exhalation resulted in a substantial decrease in ethane levels, a moderate decrease in pentane levels and an increase in isoprene levels. The major fractions of exhaled ethane, pentane and isoprene seem to be of systemic origin. There was, however, a tendency for ethane to be flow rate dependent in asthmatic subjects, although to a very limited extent, suggesting that small amounts of ethane may be formed in the airways.

Uptake of silver nanoparticles by monocytic THP-1 cells depends on particle size and presence of serum proteins

NASA Astrophysics Data System (ADS)

Kettler, Katja; Giannakou, Christina; de Jong, Wim H.; Hendriks, A. Jan; Krystek, Petra

2016-09-01

Human health risks by silver nanoparticle (AgNP) exposure are likely to increase due to the increasing number of NP-containing products and demonstrated adverse effects in various cell lines. Unfortunately, results from (toxicity) studies are often based on exposure dose and are often measured only at a fixed time point. NP uptake kinetics and the time-dependent internal cellular concentration are often not considered. Macrophages are the first line of defense against invading foreign agents including NPs. How macrophages deal with the particles is essential for potential toxicity of the NPs. However, there is a considerable lack of uptake studies of particles in the nanometer range and macrophage-like cells. Therefore, uptake rates were determined over 24 h for three different AgNPs sizes (20, 50 and 75 nm) in medium with and without fetal calf serum. Non-toxic concentrations of 10 ng Ag/mL for monocytic THP-1 cells, representing realistic exposure concentration for short-term exposures, were chosen. The uptake of Ag was higher in medium without fetal calf serum and showed increasing uptake for decreasing NP sizes, both on NP mass and on number basis. Internal cellular concentrations reached roughly 32/10 %, 25/18 % and 21/15 % of the nominal concentration in the absence of fetal calf serum/with fetal calf serum for 20-, 50- and 75-nm NPs, respectively. Our research shows that uptake kinetics in macrophages differ for various NP sizes. To increase the understanding of the mechanism of NP toxicity in cells, the process of uptake (timing) should be considered.

Alterations by glyburide of effects of BRL 34915 and P 1060 on contraction, 86Rb efflux and the maxi-K+ channel in rat portal vein

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

Hu, S.L.; Kim, H.S.; Okolie, P.

1990-05-01

Effects of the K+ channel blocking agent, glyburide, on the actions of two K+ channel openers, BRL 34915 (cromakalim) and P 1060 (Leo), a potent pinacidil derivative (N-(t-butyl)-N{double prime}-cyano-N{prime}-3-pyridyl-guanidine), were ascertained. Tension responses and {sup 86}Rb fluxes in rat portal vein strips and single channel electrophysiological recordings in enzymatically dissociated rat portal vein cells were obtained. Glyburide (0.3 microM) increased spontaneous contractile activity and caused concentration-dependent shifts in the relaxation responses to BRL 34915 and P 1060. Increases in {sup 86}Rb efflux were obtained only at much higher concentrations of BRL 34915 or P 1060, and these increases were blockedmore » only at higher concentrations of glyburide (5.0 microM). BRL 34915 and P 1060 specifically increase the open-state probability of the Ca+(+)-activated K+ (maxi-K+) channel, and these actions are blocked by glyburide and also by charybdotoxin. Changes in single channel activity and contractile responsiveness occur at similar concentrations of agonists and antagonists. Thus, the membrane channel in rat portal vein affected by glyburide, BRL 34915 and P 1060 appears to be the Ca+(+)-activated maxi-K+ channel (that does not show ATP dependence under the conditions of these experiments). Concentrations of agonists and antagonists effective on maxi-K+ channel activity correspond to those affecting contractile responsiveness and are lower than those eliciting changes in {sup 86}Rb flux.« less

Interdependence of free zinc changes and protein complex assembly - insights into zinc signal regulation.

PubMed

Kocyła, Anna; Adamczyk, Justyna; Krężel, Artur

2018-01-24

Cellular zinc (Zn(ii)) is bound with proteins that are part of the proteomes of all domains of life. It is mostly utilized as a catalytic or structural protein cofactor, which results in a vast number of binding architectures. The Zn(ii) ion is also important for the formation of transient protein complexes with a Zn(ii)-dependent quaternary structure that is formed upon cellular zinc signals. The mechanisms by which proteins associate with and dissociate from Zn(ii) and the connection with cellular Zn(ii) changes remain incompletely understood. In this study, we aimed to examine how zinc protein domains with various Zn(ii)-binding architectures are formed under free Zn(ii) concentration changes and how formation of the Zn(ii)-dependent assemblies is related to the protein concentration and reactivity. To accomplish these goals we chose four zinc domains with different Zn(ii)-to-protein binding stoichiometries: classical zinc finger (ZnP), LIM domain (Zn 2 P), zinc hook (ZnP 2 ) and zinc clasp (ZnP 1 P 2 ) folds. Our research demonstrated a lack of changes in the saturation level of intraprotein zinc binding sites, despite various peptide concentrations, while homo- and heterodimers indicated a concentration-dependent tendency. In other words, at a certain free Zn(ii) concentration, the fraction of a formed dimeric complex increases or decreases with subunit concentration changes. Secondly, even small or local changes in free Zn(ii) may significantly affect protein saturation depending on its architecture, function and subcellular concentration. In our paper, we indicate the importance of interdependence of free Zn(ii) availability and protein subunit concentrations for cellular zinc signal regulation.

Threonine deaminase from extremely halophilic bacteria - Cooperative substrate kinetics and salt dependence.

NASA Technical Reports Server (NTRS)

Lieberman, M. M.; Lanyi, J. K.

1972-01-01

The effect of salt on the activity, stability, and allosteric properties of catabolic threonine deaminase from Halobacterium cutirubrum was studied. The enzyme exhibits sigmoidal kinetics with the substrate, threonine. The Hill slope is 1.55 at pH 10. The enzyme is activated by ADP at low substrate concentrations. In the presence of this effector, sigmoidal kinetics are no longer observed. At pH 10, in the absence of ADP, enzyme activity increases with increasing NaCl concentration from 0 to 4 M.

Concentration-Dependent Protection by Ethanol Extract of Propolis against γ-Ray-Induced Chromosome Damage in Human Blood Lymphocytes.

PubMed

Montoro, A; Barquinero, J F; Almonacid, M; Montoro, A; Sebastià, N; Verdú, G; Sahuquillo, V; Serrano, J; Saiz, M; Villaescusa, J I; Soriano, J M

2011-01-01

Radioprotection with natural products may be relevant to the mitigation of ionizing radiation-induced damage in mammalian systems; in this sense, propolis extracts have shown effects such as antioxidant, antitumoral, anti-inflammatory, and immunostimulant. We report for the first time a cytogenetic study to evaluate the radioprotective effect, in vitro, of propolis against radiation-induced chromosomal damage. Lymphocytes were cultured with increasing concentrations of ethanol extract of propolis (EEP), including 20, 40, 120, 250, 500, 750, 1000, and 2000 μg mL(-1) and then exposed to 2 Gy γ-rays. A significant and concentration-dependent decrease is observed in the frequency of chromosome aberrations in samples treated with EEP. The protection against the formation of dicentrics was concentration-dependent, with a maximum protection at 120 μg mL(-1) of EEP. The observed frequency of dicentrics is described as negative exponential function, indicating that the maximum protectible fraction of dicentrics is approximately 44%. Free radical scavenging and antioxidant activities are the mechanisms that these substances use to protect cells from ionizing radiation.

Concentration-Dependent Protection by Ethanol Extract of Propolis against γ-Ray-Induced Chromosome Damage in Human Blood Lymphocytes

PubMed Central

Montoro, A.; Barquinero, J. F.; Almonacid, M.; Montoro, A.; Sebastià, N.; Verdú, G.; Sahuquillo, V.; Serrano, J.; Saiz, M.; Villaescusa, J. I.; Soriano, J. M.

2011-01-01

Radioprotection with natural products may be relevant to the mitigation of ionizing radiation-induced damage in mammalian systems; in this sense, propolis extracts have shown effects such as antioxidant, antitumoral, anti-inflammatory, and immunostimulant. We report for the first time a cytogenetic study to evaluate the radioprotective effect, in vitro, of propolis against radiation-induced chromosomal damage. Lymphocytes were cultured with increasing concentrations of ethanol extract of propolis (EEP), including 20, 40, 120, 250, 500, 750, 1000, and 2000 μg mL−1 and then exposed to 2 Gy γ-rays. A significant and concentration-dependent decrease is observed in the frequency of chromosome aberrations in samples treated with EEP. The protection against the formation of dicentrics was concentration-dependent, with a maximum protection at 120 μg mL−1 of EEP. The observed frequency of dicentrics is described as negative exponential function, indicating that the maximum protectible fraction of dicentrics is approximately 44%. Free radical scavenging and antioxidant activities are the mechanisms that these substances use to protect cells from ionizing radiation. PMID:20981159

Hydrogen absorption and its effect on magnetic properties of Nd2Fe14B

NASA Astrophysics Data System (ADS)

Bezdushnyi, R.; Damianova, R.; Tereshina, I. S.; Pankratov, N. Yu.; Nikitin, S. A.

2018-05-01

Magnetic properties of hydrides of the intermetallic compound Nd2Fe14BHx are investigated in the temperature range covering the Curie temperatures (TC) of the compounds (up to 670 K). The temperature dependencies of magnetization are measured under continuous control of hydrogen content in the investigated samples. The dependencies of Curie and spin-reorientation transition (TSR) temperatures on the hydrogen concentration are studied in detail. The dependence of hydrogen concentration on pressure at a constant temperature (near TC) and on the temperature at various pressures are obtained. We attempted to estimate the contributions of the unit cell volume increase upon hydrogenation and the electronic structure change in the variation of TC of the hydrogenated Nd2Fe14 B .

Acetylcysteine reduces plasma homocysteine concentration and improves pulse pressure and endothelial function in patients with end-stage renal failure.

PubMed

Scholze, Alexandra; Rinder, Christiane; Beige, Joachim; Riezler, Reiner; Zidek, Walter; Tepel, Martin

2004-01-27

Increased oxidative stress, elevated plasma homocysteine concentration, increased pulse pressure, and impaired endothelial function constitute risk factors for increased mortality in patients with end-stage renal failure. We investigated the metabolic and hemodynamic effects of intravenous administration of acetylcysteine, a thiol-containing antioxidant, during a hemodialysis session in a prospective, randomized, placebo-controlled crossover study in 20 patients with end-stage renal failure. Under control conditions, a hemodialysis session reduced plasma homocysteine concentration to 58+/-22% predialysis (mean+/-SD), whereas in the presence of acetylcysteine, the plasma homocysteine concentration was significantly more reduced to 12+/-7% predialysis (P<0.01). The reduction of plasma homocysteine concentration was significantly correlated with a reduction of pulse pressure. A 10% decrease in plasma homocysteine concentration was associated with a decrease of pulse pressure by 2.5 mm Hg. Analysis of the second derivative of photoplethysmogram waveform showed changes of arterial wave reflectance during hemodialysis in the presence of acetylcysteine, indicating improved endothelial function. Acetylcysteine-dependent increase of homocysteine removal during a hemodialysis session improves plasma homocysteine concentration, pulse pressure, and endothelial function in patients with end-stage renal failure.

Frequency-Dependent Capacitance of Hydrophobic Membranes Containing Fixed Negative Charges

PubMed Central

Ilani, Asher

1968-01-01

Filters containing fixed negative charges were saturated with hydrophobic solvent and interposed between aqueous solutions. The capacitance of such membranes was measured in the frequency range of 0.05-30 kc. The capacitance increased with decrease in frequency. The frequency dependence of the capacitance was sensitive to nature of the cation present and to salt concentration in the aqueous solution. It is suggested that variation of membrane resistivity in the space charge region of the membrane is responsible for this phenomenon. Possible effects of the potential and counterion concentration profiles at the membrane-water interface are discussed. PMID:5699796

Dependence of mobility on the electron concentration upon scattering at polar optical phonons in A{sup III}–N nitrides

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

Borisenko, S. I., E-mail: sib@tpu.ru

2016-04-15

The dependence of the effective relaxation time on the electron concentration in A{sup III}–N nitrides in the case of electron scattering at polar longitudinal optical phonons is calculated by the marching method. The method takes into account the inelasticity of electron scattering at polar optical phonons for nitrides in the zinc-blende approximation. The calculations show a substantial increase in mobility in samples with a degenerate electron gas, if screening of the long-range potential of polar longitudinal optical phonons is taken into account.

Nicotine-induced stimulation of steroidogenesis in adrenocortical cells of the cat.

PubMed Central

Rubin, R P; Warner, W

1975-01-01

1. The effect of nicotine on steroid production and release from trypsin-dispersed cat adrenocortical cells was investigated. 2. Nicotine, like adrenocorticotrophin (ACTH), elicited a dose-dependent increase in steroidogenesis, which depended upon the presence of calcium in the medium. 3. Augmented steroid production evoked by submaximal concentrations of ACTH monobutyryl cyclic adenosine 3',5'-monophosphate (AMP), or prostaglandin E2 was further enhanced by steroidogenic concentrations of nicotine. 4. These results are discussed in relation to the possible mode of action of nicotine on cortical cells and to the potential consequences of smoking during stress. PMID:165845

Toxicity of silver nanoparticles in zebrafish models

NASA Astrophysics Data System (ADS)

Asharani, P. V.; Lian Wu, Yi; Gong, Zhiyuan; Valiyaveettil, Suresh

2008-06-01

This study was initiated to enhance our insight on the health and environmental impact of silver nanoparticles (Ag-np). Using starch and bovine serum albumin (BSA) as capping agents, silver nanoparticles were synthesized to study their deleterious effects and distribution pattern in zebrafish embryos (Danio rerio). Toxicological endpoints like mortality, hatching, pericardial edema and heart rate were recorded. A concentration-dependent increase in mortality and hatching delay was observed in Ag-np treated embryos. Additionally, nanoparticle treatments resulted in concentration-dependent toxicity, typified by phenotypes that had abnormal body axes, twisted notochord, slow blood flow, pericardial edema and cardiac arrhythmia. Ag+ ions and stabilizing agents showed no significant defects in developing embryos. Transmission electron microscopy (TEM) of the embryos demonstrated that nanoparticles were distributed in the brain, heart, yolk and blood of embryos as evident from the electron-dispersive x-ray analysis (EDS). Furthermore, the acridine orange staining showed an increased apoptosis in Ag-np treated embryos. These results suggest that silver nanoparticles induce a dose-dependent toxicity in embryos, which hinders normal development.

Two nucleotide binding sites modulate ( sup 3 H) glyburide binding to rat cortex membranes

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

Johnson, D.E.; Gopalakrishnan, M.; Triggle, D.J.

1991-03-11

The effects of nucleotides on the binding of the ATP-dependent K{sup +}-channel antagonist ({sup 3}H)glyburide (GLB) to rat cortex membranes were examined. Nucleotide triphosphates (NTPs) and nucleotide diphosphate (NDPs) inhibited the binding of GLB. This effect was dependent on the presence of dithiothreitol (DTT). Inhibition of binding by NTPs, with the exception of ATP{gamma}S, was dependent on the presence of Mg{sup 2+}. GLB binding showed a biphasic response to ADP: up to 3 mM, ADP inhibited binding, and above this concentration GLB binding increased rapidly, and was restored to normal levels by 10 mM ADP. In the presence of Mg{supmore » 2+}, ADP did not stimulate binding. Saturation analysis in the presence of Mg{sup 2+} and increasing concentrations of ADP showed that ADP results primarily in a change of the B{sub max} for GLB binding. The differential effects of NTPS and NDPs indicate that two nucleotide binding sites regulate GLB binding.« less

The Effect of Ultrafine Process on the Dissolution, Antibacterial Activity, and Cytotoxicity of Coptidis rhizoma

PubMed Central

Jiang, Zhen-Yu; Deng, Hai-Ying; Yu, Zhi-Jun; Ni, Jun-Yan; Kang, Si-He

2016-01-01

Background: The dosage of herb ultrafine particle (UFP) depended on the increased level of its dissolution, toxicity, and efficacy. Objective: The dissolution, antibacterial activity, and cytotoxicity of Coptidis rhizoma (CR) UFP were compared with those of traditional decoction (TD). Materials and Methods: The dissolution of berberine (BBR) of CR TD and UFP was determined by high-performance liquid chromatography. The antibacterial activity of CR extract was assayed by plate-hole diffusion and broth dilution method; the inhibitory effect of rat serums against bacteria growth was evaluated after orally given CR UFP or TD extract. The cytotoxicity of CR extract was evaluated by 3-(4,5-dimethylthiazol-2-Yl)-2,5-diphenyltetrazolium bromide assay. Results: The dissolution amount of BBR from CR UFP increased 6–8-folds in comparison to TD at 2 min, the accumulative amount of BBR in both UFP and TD group increased in a time-dependent manner. The minimal inhibitory concentrations and minimal bactericidal concentrations of CR UFP extract decreased to 1/2~1/4 of those of TD extract. The inhibitory effect of rat serums against bacteria growth decreased time-dependently, and no statistical difference was observed between two groups at each time point. The 50% cytotoxic concentrations of UFP extract increased 1.66~1.97 fold than those of TD. Conclusions: The antibacterial activity and cytotoxicity of CR UFP increased in a dissolution-effect manner in vitro, the increased level of cytotoxicity was lower than that of antibacterial activity, and the inhibitory effect of rat serums containing drugs of UFP group did not improve. SUMMARY Ultrafine grinding process caused a rapid increase of BBR dissolution from CR.The antibacterial activity and cytotoxicity of UFP extract in vitro increased in a dissolution-effect manner, but the cytotoxicity increased lower than the antibacterial activity.The antibacterial activity of rat serums of UFP group did not improve in comparison to that of TD group PMID:26941540

Voltage-dependent formation of gramicidin channels in lipid bilayers.

PubMed Central

Sandblom, J; Galvanovskis, J; Jilderos, B

2001-01-01

The formation kinetics of gramicidin A channels in lipid bilayer membranes has been characterized as a function of voltage for different solution conditions and membrane composition. The frequency of channel events was measured during the application of voltage ramps and counted in given intervals, a procedure that eliminated the effects of drift in gramicidin concentration. The formation rate was found to increase strongly with voltages up to approximately 50 mV and then to level off slightly. The shape of the voltage dependence was independent of lipid solvent and ramp speed but differed for different ions and different solution concentrations. This suggested an ion occupancy effect on the formation rate that was further supported by the fact that the minimum of the formation rate was shifted toward the equilibrium potential in asymmetric solution concentrations. The effects are explained in terms of a model that contains two contributions to the voltage dependence, a voltage-dependent ion binding to the monomers and a polarization of monomers by the applied electric field and by the occupied ions. The theory is found to give a good fit to experimental data. PMID:11463628

Hydrologic controls on DOC, As and Pb export from a polluted peatland - the importance of heavy rain events, antecedent moisture conditions and hydrological connectivity

NASA Astrophysics Data System (ADS)

Broder, T.; Biester, H.

2015-08-01

Bogs can store large amounts of lead (Pb) and arsenic (As) from atmospheric deposition of anthropogenic emissions. Pb and As are exported along with dissolved organic carbon (DOC) from these organic-rich systems, but it is not yet clear which hydrological (pre)conditions favor their export. This study combines a 1-year monitoring of precipitation, bog water level and pore water concentration changes with bog discharge and DOC, iron, As and Pb stream concentrations. From these data, annual DOC, As, and Pb exports were calculated. Concentrations ranged from 5 to 30 mg L-1 for DOC, 0.2 to 1.9 μg L-1 for As, and 1.3 to 12 μg L-1 for Pb, with highest concentrations in late summer. As and Pb concentrations significantly correlated with DOC concentrations. Fluxes depended strongly on discharge, as 40 % of As and 43 % of Pb were exported during 10 % of the time with the highest discharge, pointing out the over-proportional contribution of short-time, high-discharge events to annual As, Pb and DOC export. Exponential increase in element export from the bog is explained by connection of additional DOC, As and Pb pools in the acrotelm during water table rise, which is most pronounced after drought. Pb, As and DOC concentrations in pore water provide evidence of an increase in the soluble Pb pool as soon as the peat layer becomes hydrologically connected, while DOC and As peak concentrations in runoff lag behind in comparison to Pb. Our data indicate a distinct bog-specific discharge threshold of 8 L s-1, which is thought to depend mainly on the bogs size and drainage conditions. Above this threshold, element concentrations do not further increase and discharge becomes diluted. Combining pore water and discharge data shows that As and Pb exports are dependent on not only the amount of precipitation and discharge but also on the frequency and depth of water table fluctuations. Comparing the annual bog As and Pb export with element inventories indicates that As is much more mobilized than Pb, with annual fluxes accounting for 0.85 and 0.27 ‰ of total As and Pb inventory, respectively.

Lateral dimension-dependent antibacterial activity of graphene oxide sheets.

PubMed

Liu, Shaobin; Hu, Ming; Zeng, Tingying Helen; Wu, Ran; Jiang, Rongrong; Wei, Jun; Wang, Liang; Kong, Jing; Chen, Yuan

2012-08-21

Graphene oxide (GO) is a promising precursor to produce graphene-family nanomaterials for various applications. Their potential health and environmental impacts need a good understanding of their cellular interactions. Many factors may influence their biological interactions with cells, and the lateral dimension of GO sheets is one of the most relevant material properties. In this study, a model bacterium, Escherichia coli ( E. coli ), was used to evaluate the antibacterial activity of well-dispersed GO sheets, whose lateral size differs by more than 100 times. Our results show that the antibacterial activity of GO sheets toward E. coli cells is lateral size dependent. Larger GO sheets show stronger antibacterial activity than do smaller ones, and they have different time- and concentration-dependent antibacterial activities. Large GO sheets lead to most cell loss after 1 h incubation, and their concentration strongly influences antibacterial activity at relative low concentration (<10 μg/mL). In contrast, when incubating with small GO sheets up to 4 h, the inactivation rate of E. coli cells continues increasing. The increase of small GO sheet concentration also results in persistent increases in their antibacterial activity. In this study, GO sheets with different lateral sizes are all well dispersed, and their oxidation capacity toward glutathione is similar, consistent with X-ray photoelectron spectroscopy and ultraviolet-visible absorption spectroscopy results. This suggests the lateral size-dependent antibacterial activity of GO sheets is caused by neither their aggregation states, nor oxidation capacity. Atomic force microscope analysis of GO sheets and cells shows that GO sheets interact strongly with cells. Large GO sheets more easily cover cells, and cells cannot proliferate once fully covered, resulting in the cell viability loss observed in the followed colony counting test. In contrast, small GO sheets adhere to the bacterial surfaces, which cannot effectively isolate cells from environment. This study highlights the importance of tailoring the lateral dimension of GO sheets to optimize the application potential with minimal risks for environmental health and safety.

Dose-dependent effects of homologous seminal plasma on motility and kinematic characteristics of post-thaw stallion epididymal spermatozoa.

PubMed

Neuhauser, S; Dörfel, S; Handler, J

2015-05-01

Preservation of epididymal spermatozoa is important to save genetic material of endangered species and breeds, or in case of unexpected injury, which will end the breeding career of valuable sires. Seminal plasma (SP) influences sperm quality in a dose-dependent manner and its addition to preserved semen immediately before insemination may be beneficial for sperm fertility. Increased plasma membrane stability of epididymal spermatozoa reduces freezing injury of cells, and the addition of SP after freezing and thawing might have activating and protecting effects on spermatozoa within the female genital tract. In this study, epididymal spermatozoa were harvested by retrograde flush of the epididymal cauda immediately after routine castration and frozen. Seminal plasma was collected from other six stallions. Homologous SP (SP from the same species, but from a different animal) was added to frozen-thawed epididymal spermatozoa at concentrations of 0, 5, 20, 50 and 80% SP. Addition of SP increased sperm motility and influenced kinematic values in a dose-dependent manner (p < 0.05). Motility improved at concentrations of 20 and 50% SP, but did not further increase at 80% SP. There was no difference in sperm motility among SP from six different donor stallions regardless of the concentrations of SP (p > 0.05). Total and progressive motility of ten frozen-thawed epididymal spermatozoa samples collected from different stallions after dilution with extender and 5, 20, 50 or 80% SP differed significantly (p < 0.05). In conclusion, addition of homologous SP to frozen-thawed stallion epididymal spermatozoa immediately improved motility in a dose-dependent manner regardless of semen quality of SP donor stallions. This might positively influence fertility when SP is added before insemination. Moreover, there seems to be a threshold level of SP concentration for optimal improvement of sperm motility. © 2015 American Society of Andrology and European Academy of Andrology.

Green Tea Potentially Ameliorates Bisphenol A-Induced Oxidative Stress: An In Vitro and In Silico Study

PubMed Central

Suthar, Hiral; Verma, R. J.; Patel, Saumya; Jasrai, Y. T.

2014-01-01

The present investigation was an attempt to elucidate oxidative stress induced by bisphenol A on erythrocytes and its amelioration by green tea extract. For this, venous blood samples from healthy human adults were collected in EDTA vials and used for preparation of erythrocytes suspension. When erythrocyte suspensions were treated with different concentrations of BPA/H2O2, a dose-dependent increase in hemolysis occurred. Similarly, when erythrocytes suspensions were treated with either different concentrations of H2O2 (0.05–0.25 mM) along with BPA (50 μg/mL) or 0.05 mM H2O2 along with different concentrations of BPA (50–250 μg/mL), dose-dependent significant increase in hemolysis occurred. The effect of BPA and H2O2 was found to be additive. For the confirmation, binding capacity of bisphenol A with erythrocyte proteins (hemoglobin, catalase, and glutathione peroxidase) was inspected using molecular docking tool, which showed presence of various hydrogen bonds of BPA with the proteins. The present data clearly indicates that BPA causes oxidative stress in a similar way as H2O2 . Concurrent addition of different concentrations (10–50 μg/mL) of green tea extract to reaction mixture containing high dose of bisphenol A (250 μg/mL) caused concentration-dependent amelioration in bisphenol A-induced hemolysis. The effect was significant (P < 0.05). It is concluded that BPA-induced oxidative stress could be significantly mitigated by green tea extract. PMID:25180096

Charge trapping in detector grade thallium bromide and cadmium zinc telluride: Measurement and theory

NASA Astrophysics Data System (ADS)

Elshazly, Ezzat S.; Tepper, Gary; Burger, Arnold

2010-08-01

Carrier trapping times were measured in detector grade thallium bromide (TlBr) and cadmium zinc telluride (CZT) from 300 to 110 K and the experimental data were analyzed using a trapping model. In CZT, because the majority carrier concentration is close to the intrinsic carrier concentration, the trapping time increases exponentially as the temperature decreases below about 160 K. In TlBr, the majority carrier concentration is many orders of magnitude greater than the intrinsic carrier concentration and the trapping time followed a (1/ T) 1/2 temperature dependence over the range of temperatures studied. The results of the model suggest that a moderately deep compensation center could be used to significantly increase the room temperature trapping time in TlBr.

Pressure Effects on Oxygen Concentration Flammability Thresholds of Materials for Aerospace Applications

NASA Technical Reports Server (NTRS)

Hirsch, David; Williams, Jim; Beeson, Harold

2006-01-01

Spacecraft materials selection is based on an upward flammability test conducted in a quiescent environment in the highest-expected oxygen-concentration environment. However, NASA s advanced space exploration program is anticipating using various habitable environments. Because limited data is available to support current program requirements, a different test logic is suggested to address these expanded atmospheric environments through the determination of materials self-extinguishment limits. This paper provides additional pressure effects data on oxygen concentration and partial pressure self-extinguishment limits under quiescent conditions. For the range of total pressures tested, the oxygen concentration and oxygen partial pressure flammability thresholds show a near linear function of total pressure. The oxygen concentration/oxygen partial pressure flammability thresholds depend on the total pressure and appear to increase with increasing oxygen concentration (and oxygen partial pressure). For the Constellation Program, the flammability threshold information will allow NASA to identify materials with increased flammability risk because of oxygen concentration and total pressure changes, minimize potential impacts, and allow for development of sound requirements for new spacecraft and extraterrestrial landers and habitats.

Exposure-dependent incorporation of trifluridine into DNA of tumors and white blood cells in tumor-bearing mouse.

PubMed

Yamashita, Fumiaki; Komoto, Ikumi; Oka, Hiroaki; Kuwata, Keizo; Takeuchi, Mayuko; Nakagawa, Fumio; Yoshisue, Kunihiro; Chiba, Masato

2015-08-01

Trifluridine (TFT) is an antitumor component of a novel nucleoside antitumor agent, TAS-102, which consists of TFT and tipiracil hydrochloride (thymidine phosphorylase inhibitor). Incorporation of TFT into DNA is a probable mechanism of antitumor activity and hematological toxicity. The objective of this study was to examine the TFT incorporation into tumor- and white blood cell-DNA, and to elucidate the mechanism of TFT-related effect and toxicity. TFT effect on the colony formation of mouse bone marrow cells was also investigated. Pharmacokinetics of TFT was determined in nude mice after single oral administration of TAS-102, while the antitumor activity and body weight change were evaluated in the tumor-bearing nude mice after multiple oral administrations for 2 weeks. TFT concentrations in the blood- and tumor-DNA were determined by LC/MS/MS. The colony formation was evaluated by CFU-GM assay. TFT systemic exposure in plasma increased dose-dependently. The tumor growth rate and body weight gain decreased dose-dependently, but TFT concentrations in the DNA of tumor tissues and white blood cells increased dose-dependently. TFT inhibited colony formation of bone marrow cells in a concentration-dependent manner. A significant relationship between systemic exposure of TFT and pharmacological effects including the antitumor activity and body weight change was well explained by the TFT incorporation into DNA. TFT inhibited proliferations of mouse bone marrow cells and human colorectal carcinoma cells implanted to nude mice dose-dependently. The highest tolerable TFT exposure provides the highest antitumor activity, and the hematological toxicity may serve as a potential surrogate indicator of TAS-102 efficacy.

Modelling interactions of toxicants and density dependence in wildlife populations

USGS Publications Warehouse

Schipper, Aafke M.; Hendriks, Harrie W.M.; Kauffman, Matthew J.; Hendriks, A. Jan; Huijbregts, Mark A.J.

2013-01-01

1. A major challenge in the conservation of threatened and endangered species is to predict population decline and design appropriate recovery measures. However, anthropogenic impacts on wildlife populations are notoriously difficult to predict due to potentially nonlinear responses and interactions with natural ecological processes like density dependence. 2. Here, we incorporated both density dependence and anthropogenic stressors in a stage-based matrix population model and parameterized it for a density-dependent population of peregrine falcons Falco peregrinus exposed to two anthropogenic toxicants [dichlorodiphenyldichloroethylene (DDE) and polybrominated diphenyl ethers (PBDEs)]. Log-logistic exposure–response relationships were used to translate toxicant concentrations in peregrine falcon eggs to effects on fecundity. Density dependence was modelled as the probability of a nonbreeding bird acquiring a breeding territory as a function of the current number of breeders. 3. The equilibrium size of the population, as represented by the number of breeders, responded nonlinearly to increasing toxicant concentrations, showing a gradual decrease followed by a relatively steep decline. Initially, toxicant-induced reductions in population size were mitigated by an alleviation of the density limitation, that is, an increasing probability of territory acquisition. Once population density was no longer limiting, the toxicant impacts were no longer buffered by an increasing proportion of nonbreeders shifting to the breeding stage, resulting in a strong decrease in the equilibrium number of breeders. 4. Median critical exposure concentrations, that is, median toxicant concentrations in eggs corresponding with an equilibrium population size of zero, were 33 and 46 μg g−1 fresh weight for DDE and PBDEs, respectively. 5. Synthesis and applications. Our modelling results showed that particular life stages of a density-limited population may be relatively insensitive to toxicant impacts until a critical threshold is crossed. In our study population, toxicant-induced changes were observed in the equilibrium number of nonbreeding rather than breeding birds, suggesting that monitoring efforts including both life stages are needed to timely detect population declines. Further, by combining quantitative exposure–response relationships with a wildlife demographic model, we provided a method to quantify critical toxicant thresholds for wildlife population persistence.

Non-monotonic changes in clonogenic cell survival induced by disulphonated aluminum phthalocyanine photodynamic treatment in a human glioma cell line

PubMed Central

2010-01-01

Background Photodynamic therapy (PDT) involves excitation of sensitizer molecules by visible light in the presence of molecular oxygen, thereby generating reactive oxygen species (ROS) through electron/energy transfer processes. The ROS, thus produced can cause damage to both the structure and the function of the cellular constituents resulting in cell death. Our preliminary investigations of dose-response relationships in a human glioma cell line (BMG-1) showed that disulphonated aluminum phthalocyanine (AlPcS2) photodynamically induced loss of cell survival in a concentration dependent manner up to 1 μM, further increases in AlPcS2concentration (>1 μM) were, however, observed to decrease the photodynamic toxicity. Considering the fact that for most photosensitizers only monotonic dose-response (survival) relationships have been reported, this result was unexpected. The present studies were, therefore, undertaken to further investigate the concentration dependent photodynamic effects of AlPcS2. Methods Concentration-dependent cellular uptake, sub-cellular localization, proliferation and photodynamic effects of AlPcS2 were investigated in BMG-1 cells by absorbance and fluorescence measurements, image analysis, cell counting and colony forming assays, flow cytometry and micronuclei formation respectively. Results The cellular uptake as a function of extra-cellular AlPcS2 concentrations was observed to be biphasic. AlPcS2 was distributed throughout the cytoplasm with intense fluorescence in the perinuclear regions at a concentration of 1 μM, while a weak diffuse fluorescence was observed at higher concentrations. A concentration-dependent decrease in cell proliferation with accumulation of cells in G2+M phase was observed after PDT. The response of clonogenic survival after AlPcS2-PDT was non-monotonic with respect to AlPcS2 concentration. Conclusions Based on the results we conclude that concentration-dependent changes in physico-chemical properties of sensitizer such as aggregation may influence intracellular transport and localization of photosensitizer. Consequent modifications in the photodynamic induction of lesions and their repair leading to different modes of cell death may contribute to the observed non-linear effects. PMID:20433757

Homocysteine induces oxidative stress to damage trabecular meshwork cells.

PubMed

You, Zhi-Peng; Zhang, Yue-Zhi; Zhang, Yu-Lan; Shi, Lu; Shi, Ke

2018-05-01

The aim of the present study was to investigate the effect of homocysteine (Hcy) in on human trabecular meshwork cells (HTMCs). A total of 41 patients with primary open-angle glaucoma (POAG) and 53 patients with senile cataracts (control group) were recruited. Plasma and aqueous humor samples were collected and the Hcy concentrations were determined using enzymatic cycling assays. In cell experiments, normal HTMCs were passaged and randomly divided into a blank control group, a normal HTMC group and experimental groups, which were treated with different concentrations of Hcy. The HTMC activities were detected using the Cell Counting Kit-8 method and the HTMC mitochondrial membrane potential (MMP) was detected using JC-1 staining. Reactive oxygen species (ROS) released by trabecular meshwork cells was detected using flow cytometry and superoxide dismjutase-1 (SOD1) expression was detected using immunoblotting. The results revealed that the concentration of Hcy in the plasma and aqueous humor of the POAG group (14.44±0.86 and 1.60±0.27 µmol/l, respectively) was significantly higher compared with the control group (10.82±0.29 and 0.69±0.39 µmol/l). All tested concentrations (30, 100, 300 and 1,000 µmol/l) of Hcy reduced the MMP in HTMCs and inhibited HTMC proliferation in a dose-dependent manner. ROS production by HTMCs significantly increased with increased concentrations of Hcy, whereas SOD1 expression significantly decreased in a dose-dependent manner. In summary, patients with POAG were demonstrated to have increased concentrations of Hcy in the plasma and aqueous humor. High concentrations of Hcy in HTMCs induced an oxidative stress state, thereby further inhibiting HTMC proliferation. The results of the present study demonstrate that Hcy may be a potential treatment target in patients with POAG.

Extracellular Ca(2+)-dependent enhancement of cytocidal potency of zoledronic acid in human oral cancer cells.

PubMed

Inoue, Sayaka; Arai, Naoya; Tomihara, Kei; Takashina, Michinori; Hattori, Yuichi; Noguchi, Makoto

2015-08-15

Direct antitumor effects of bisphosphonates (BPs) have been demonstrated in various cancer cells in vitro. However, the effective concentrations of BPs are typically much higher than their clinically relevant concentrations. Oral cancers frequently invade jawbone and may lead to the release of Ca(2+) in primary lesions. We investigated the effects of the combined application of zoledronic acid (ZA) and Ca(2+) on proliferation and apoptosis of oral cancer cells. Human oral cancer cells, breast cancer cells, and colon cancer cells were treated with ZA at a wide range of concentrations in different Ca(2+) concentration environments. Under a standard Ca(2+) concentration (0.6mM), micromolar concentrations of ZA were required to inhibit oral cancer cell proliferation. Increasing extracellular Ca(2+) concentrations greatly enhanced the potency of the ZA cytocidal effect. The ability of Ca(2+) to enhance the cytocidal effects of ZA was negated by the Ca(2+)-selective chelator EGTA. In contrast, the cytocidal effect of ZA was less pronounced in breast and colon cancer cells regardless of whether extracellular Ca(2+) was elevated. In oral cancer cells incubated with 1.6mM Ca(2+), ZA up-regulated mitochondrial Bax expression and increased mitochondrial Ca(2+) uptake. This was associated with decreased mitochondrial membrane potential and increased release of cytochrome c. We suggest that ZA can specifically produce potent cytocidal activity in oral cancer cells in an extracellular Ca(2+)-dependent manner, implying that BPs may be useful for treatment of oral squamous cell carcinoma with jawbone invasion leading to the hypercalcemic state. Copyright © 2015 Elsevier B.V. All rights reserved.

Oxidation of RyR2 Has a Biphasic Effect on the Threshold for Store Overload-Induced Calcium Release.

PubMed

Waddell, Helen M M; Zhang, Joe Z; Hoeksema, Katie J; McLachlan, Julia J; McLay, Janet C; Jones, Peter P

2016-06-07

At the single-channel level, oxidation of the cardiac ryanodine receptor (RyR2) is known to activate and inhibit the channel depending on the level of oxidation. However, the mechanisms through which these changes alter the activity of RyR2 in a cellular setting are poorly understood. In this study, we determined the effect of oxidation on a common form of RyR2 regulation; store overload-induced Ca(2+) release (SOICR). We found that oxidation resulted in concentration and time-dependent changes in the activation threshold for SOICR. Low concentrations of the oxidant H2O2 resulted in a decrease in the threshold for SOICR, which led to an increase in SOICR events. However, higher concentrations of H2O2, or prolonged exposure, reversed these changes and led to an increase in the threshold for SOICR. This increase in the threshold for SOICR in most cells was to such an extent that it led to the complete inhibition of SOICR. Acute exposure to high concentrations of H2O2 led to an initial decrease and then increase in the threshold for SOICR. In the majority of cells the increased threshold could not be reversed by the application of the reducing agent dithiothreitol. Therefore, our data suggest that low levels of RyR2 oxidation increase the channel activity by decreasing the threshold for SOICR, whereas high levels of RyR2 oxidation irreversibly increase the threshold for SOICR leading to an inhibition of RyR2. Combined, this indicates that oxidation regulates RyR2 by the same mechanism as phosphorylation, methylxanthines, and mutations, via changes in the threshold for SOICR. Copyright © 2016 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Concentration-dependence of the explosion characteristics of chlorine dioxide gas.

PubMed

Jin, Ri-ya; Hu, Shuang-qi; Zhang, Yin-ghao; Bo, Tao

2009-07-30

The explosion characteristics of chlorine dioxide gas have been studied for the first time in a cylindrical exploder with a shell capacity of 20 L. The experimental results have indicated that the lower concentration limit for the explosive decomposition of chlorine dioxide gas is 9.5% ([ClO(2)]/[air]), whereas there is no corresponding upper concentration limit. Under the experimental conditions, and within the explosion limits, the pressure of explosion increases with increasing concentration of chlorine dioxide gas; the maximum pressure of explosion relative to the initial pressure was measured as 0.024 MPa at 10% ClO(2) and 0.641 MPa at 90% ClO(2). The induction time (the time from the moment of sparking to explosion) has also been found to depend on the concentration of chlorine dioxide gas; thus, at 10% ClO(2) the induction time was 2195 ms, but at 90% ClO(2) the induction time was just 8 ms. The explosion reaction mechanism of ClO(2) is of a degenerate chain-branching type involving the formation of a stable intermediate (Cl(2)O(3)), from which the chain-branching occurs. Chain initiation takes place at the point of ignition and termination takes place at the inner walls of the exploder.

Evaluation of taste-masking effects of pharmaceutical sweeteners with an electronic tongue system.

PubMed

Choi, Du Hyung; Kim, Nam Ah; Nam, Tack Soo; Lee, Sangkil; Jeong, Seong Hoon

2014-03-01

Electronic tongue systems have been developed for taste measurement of bitter drug substances in accurate taste comparison to development palatable oral formulations. This study was to evaluate the taste masking effect of conventional pharmaceutical sweeteners such as neohesperidin dihydrochalcone, sucrose, sucralose and aspartame. The model drugs were acetaminophen, ibuprofen, tramadol hydrochloride, and sildenafil citrate (all at 20 mM). The degree of bitterness was measured by a multichannel taste sensor system (an electronic tongue). The data was collected by seven sensors and analyzed by a statistical method of principal components analysis (PCA). The effect of taste masking excipient was dependent on the type of model drug. Changing the concentration of taste masking excipients affected the sensitivity of taste masking effect according to the type of drug. As the excipient concentration increased, the effect of taste masking increased. Moreover, most of the sensors showed a concentration-dependent pattern of the taste-masking agents as higher concentration provided higher selectivity. This might indicate that the sensors can detect small concentration changes of a chemical in solution. These results suggest that the taste masking could be evaluated based on the data of the electronic tongue system and that the formulation development process could be performed in a more efficient way.

Partitioning of lysolipids, fatty acids and their mixtures in aqueous lipid bilayers: solute concentration/composition effects.

PubMed

Singh, Jasmeet; Lai, Amy Jo; Alaee, Yasmin; Ranganathan, Radha

2014-01-01

Distributions of lysopalmitoylphosphatidylcholine (LPPC), palmitic acid (PA) and their 1:1 mixtures between water and dipalmitoylphosphatidylcholine (DPPC) bilayer were determined using a fluorescence probe that selectively detects only the solutes in water. Water solute concentrations were obtained at each of several lipid concentrations. Dynamic Light Scattering experiments confirmed that the lipid/solute aggregates were vesicles in the concentration range investigated. Lipid concentration dependence of the solute component in water was fit to a thermodynamic model of solute distribution between two coexisting solvents. Water/bilayer partition coefficient and the free energy of transfer, for each of these solutes were determined from the fit. Main findings are: (1) Water/bilayer partition coefficient of solute is greater for 2 to 10% solute mole fraction than for 0 to 2%, signaling solute induced bilayer perturbation that increases bilayer solubility, beginning at 2% solute mole fraction. (2) Partition coefficients are in the order LPPC

Partitioning of Lysolipids, Fatty Acids and Their Mixtures in Aqueous Lipid Bilayers: Solute Concentration / Composition Effects

PubMed Central

Singh, Jasmeet; Lai, Amy Jo; Alaee, Yasmin; Ranganathan, Radha

2013-01-01

Distribution of lysopalmitoylphosphatidylcholine (LPPC), Palmitic acid (PA) and their 1:1 mixtures between water and dipalmitoylphosphatidylcholine (DPPC) bilayer were determined using a fluorescence probe that selectively detects only the solutes in water. Water solute concentrations were obtained at each of several lipid concentrations. Dynamic Light Scattering experiments confirmed that the lipid/solute aggregates were vesicles in the concentration range investigated. Lipid concentration dependence of the solute component in water was fit to a thermodynamic model of solute distribution between two coexisting solvents. Water/bilayer partition coefficient and the free energy of transfer, for each of these solutes were determined from the fit. Main findings are: (1) Water/bilayer partition coefficient of solute is greater for 2 to 10 % solute mole fraction than for 0 to 2 %, signaling solute induced bilayer perturbation that increases bilayer solubility, beginning at 2 % solute mole fraction. (2) Partition coefficients are in the order LPPC

N-acetylcysteine does not improve the endothelial and smooth muscle function in the human saphenous vein.

PubMed

Sharif, Muhammad Anees; Bayraktutan, Ulvi; Young, Ian Stuart; Soong, Chee Voon

2007-01-01

Oxidative stress can lead to vein graft dysfunction in the saphenous vein. This ex vivo study is aimed to compare the effects of increasing concentrations of the antioxidant N-acetylcysteine (NAC) with heparinized saline (HS) on endothelial and smooth muscle function in the human saphenous vein. Long saphenous vein segment obtained during infrainguinal bypass surgery was divided into 7 rings; 1 immersed in HS and the remaining 6 in increasing NAC concentrations (0.0025%, 0.005%, 0.01%, 0.02%, 0.03%, and 0.04%). Rings were mounted in an organ bath, and relaxant responses to acetylcholine and sodium nitroprusside were assessed through isometric tension studies. Endothelium-dependent relaxations were observed in 77 vein segments from 11 patients. No significant difference was seen in veins treated with either lower NAC concentrations (0.0025%, 0.005%, 0.01%, 0.02%, and 0.03%) or HS. However, HS-treated veins showed significantly better relaxation compared to those treated with maximum (0.04%) NAC (P < .05). Endothelium-independent relaxations were observed in 91 segments from 13 patients. No difference in relaxation was observed between veins treated with HS or any of the NAC concentrations. In conclusion, lower NAC concentrations do not offer better endothelial protection than HS, whereas the highest NAC concentration has a detrimental effect on endothelium-dependent relaxation. Moreover, NAC did not show beneficial effect on direct smooth muscle relaxation.

Effect of process parameters and operational mode on nitrous oxide emissions from a nitritation reactor treating reject wastewater.

PubMed

Pijuan, Maite; Torà, Josep; Rodríguez-Caballero, Adrián; César, Elvira; Carrera, Julián; Pérez, Julio

2014-02-01

Nitrous oxide (N2O) and methane emissions were monitored in a continuous granular airlift nitritation reactor from ammonium-rich wastewater (reject wastewater). N2O emissions were found to be dependent on dissolved oxygen (DO) concentration in the range of 1-4.5 mg O2/L, increasing within this range when reducing the DO values. At higher DO concentrations, N2O emissions remained constant at 2.2% of the N oxidized to nitrite, suggesting two different mechanisms behind N2O production, one dependent and one independent of DO concentration. Changes on ammonium, nitrite, free ammonia and free nitrous acid concentrations did not have an effect on N2O emissions within the concentration range tested. When operating the reactor in a sequencing batch mode under high DO concentration (>5 mg O2/L), N2O emissions increased one order of magnitude reaching values of 19.3 ± 7.5% of the N oxidized. Moreover, CH4 emissions detected were due to the stripping of the soluble CH4 that remained dissolved in the reject wastewater after anaerobic digestion. Finally, an economical and carbon footprint assessment of a theoretical scaled up of the pilot plant was conducted. Copyright © 2013 Elsevier Ltd. All rights reserved.

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

Ruiz-Ramos, Ruben; Departamento de Toxicologia, Centro de Investigacion y de Estudios Avanzados del Instituto Politecnico Nacional, 07360 Mexico D.F.; Lopez-Carrillo, Lizbeth

There is limited available information on the effects of arsenic on enzymes participating in the folate cycle. Therefore, our aim was to evaluate the effects of sodium arsenite on the protein levels of methylenetetrahydrofolate reductase (MTHFR) and dihydrofolate reductase (DHFR) and its further relationship with the expression MT1/2 and c-myc in MCF-7 cells. Arsenite treatment (0-10 muM) for 4 h decreased MTHFR levels in a concentration-dependent fashion without significant effects on DHFR. The effects on MTHFR were observed at arsenite concentrations not significantly affecting cell viability. We also observed an increase in S-phase recruitment at all concentrations probed. Lower concentrationsmore » (< 5 muM) induced cell proliferation, showing a high proportion of BrdU-stained cells, indicating a higher DNA synthesis rate. However, higher concentrations (>= 5 muM) or longer treatment periods induced apoptosis. Arsenite also induced dose-dependent increases in MT1/2 and c-Myc protein levels. The levels of MTHFR were inversely correlated to MT1/2 and c-Myc overexpression and increased S-phase recruitment. Our findings indicate that breast epithelial cells are responsive to arsenite and suggest that exposure may pose a risk for breast cancer. The reductions in MTHFR protein levels contribute to understand the mechanisms underlying the induction of genes influencing growth regulation, such as c-myc and MT1/2. However, further research is needed to ascertain if the effects here reported following short-time and high-dose exposure are relevant for human populations chronically exposed to low arsenic concentrations.« less

The seleno-organic compound ebselen impairs mitochondrial physiology and induces cell death in AR42J cells.

PubMed

Santofimia-Castaño, Patricia; Garcia-Sanchez, Lourdes; Ruy, Deborah Clea; Fernandez-Bermejo, Miguel; Salido, Gines M; Gonzalez, Antonio

2014-09-17

Ebselen is a seleno-organic compound that causes cell death in several cancer cell types. The mechanisms underlying its deleterious effects have not been fully elucidated. In this study, the effects of ebselen (1 μM-40 μM) on AR42J tumor cells have been examined. Cell viability was studied using AlamarBlue(®) test. Cell cycle phase determination was carried out by flow cytometry. Changes in intracellular free Ca(2+) concentration were followed by fluorimetry analysis of fura-2-loaded cells. Distribution of mitochondria, mitochondrial Ca(2+) concentration and mitochondrial membrane potential were monitored by confocal microscopy of cells loaded with Mitotracker Green™ FM, rhod-2 or TMRM respectively. Caspase-3 activity was calculated following the luorogenic substrate ACDEVD-AMC signal with a spectrofluorimeter. Results show that cell viability decreased in the presence of ebselen. An increase in the number of cells in the S-phase of the cell cycle was observed. Ebselen induced a concentration-dependent mobilization of Ca(2+) from agonist- and thapsigargin-sensitive Ca(2+) pools. Ebselen induced also a transient increase in mitochondrial Ca(2+) concentration, a progressive decrease of the mitochondrial membrane potential and a disruption of the mitochondrial network. Finally, a concentration-dependent increase in caspase-3 activity was detected. We conclude that ebselen exerts deleterious actions on the cells that involve the impairment of mitochondrial physiology and the activation of caspase-3-mediated apoptotic pathway. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Soil Solution Phosphorus Status and Mycorrhizal Dependency in Leucaena leucocephala†

PubMed Central

Habte, Mitiku; Manjunath, Aswathanarayan

1987-01-01

A phosphorus sorption isotherm was used to establish concentrations of P in a soil solution ranging from 0.002 to 0.807 μg/ml. The influence of P concentration on the symbiotic interaction between the tropical tree legume Leucaena leucocephala and the vesicular-arbuscular mycorrhizal (VAM) fungus Glomus fasciculatum was evaluated in pot experiments. The level of mycorrhizal infection in Leucaena roots increased as the concentration of P was raised from 0.002 to 0.153 μg/ml. Higher levels of P depressed mycorrhizal infection, but the level of infection never declined below 50%. Periodic monitoring of P contents of Leucaena subleaflets indicated that significant mycorrhizal activity was detected as early as 17 days after planting, with the activity peaking 12 to 16 days thereafter. The highest level of mycorrhizal activity was associated with a soil solution P level of 0.021 μg/ml. Even though the mycorrhizal inoculation effect diminished as the concentration of P in the soil solution was increased, mycorrhizal inoculation significantly increased P uptake and dry-matter yield of Leucaena at all levels of soil solution P examined. The concentration of P required by nonmycorrhizal L. leucocephala for maximum yield was 27 to 38 times higher than that required by mycorrhizal L. leucocephala. The results illustrate the very high dependence of L. leucocephala on VAM fungi and the significance of optimizing soil solution phosphorus for enhancing the benefits of the VAM symbiosis. PMID:16347323

Factors affecting shear thickening behavior of a concentrated injectable suspension of levodopa.

PubMed

Allahham, Ayman; Stewart, Peter; Marriott, Jennifer; Mainwaring, David

2005-11-01

Previous clinical studies on a subcutaneous injectable suspension of levodopa showed poor injectability into human tissue. When this formulation was rheologically characterised, a clinical shear thickening interval was observed at increased shear rates. The formulation parameters that contributed to this rheological behavior were systematically evaluated with the aim of removing this flow limitation while maintaining the concentration of 60% levodopa to retain the clinical applicability. The three suspension parameters examined were: levodopa volume fraction, concentration of the HPMC suspending vehicle, and particle size distribution. Shear thickening increased with the drug concentration and the critical shear rate was inversely dependent on the drug concentration. Increasing the vehicle concentration retarded the shear thickening but increased the overall suspension viscosity. There was an increase in shear thickening with increased average particle diameter. Combinations of micronized and non-micronized particles were used to prepare bimodal particle size distributions. The rheology of these bimodal distributions resulted in removal of shear thickening. This allowed the preparation of 60% levodopa formulations that showed a range of flow characteristics spanning near Newtonian flow or shear thinning at initial injectable viscosities of about 0.6 Pa.s and final viscosities in the range of 0.1 Pa.s, alleviating the shear thickening limitation of these levodopa formulations.

Magnetic and absorbing properties of M-type substituted hexaferrites BaFe{sub 12–x}Ga{sub x}O{sub 19} (0.1 < x < 1.2)

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

Trukhanov, S. V., E-mail: trukhanov@ifttp.bas-net.by; Trukhanov, A. V.; Kostishin, V. G.

2016-09-15

X-ray powder diffraction is used to determine the unit cell parameters and to refine the crystal structure of the solid solutions of M-type hexagonal barium ferrite BaFe{sub 12–x}Ga{sub x}O{sub 19} (x = 0.1–1.2) with isostructural diamagnetic cation Ga{sup 3+} substitution at T = 300 K. As the level of substitution increases, the unit cell parameters are shown to decrease monotonically. The temperature (300 K ≤ T ≤ 750 K, H = 8.6 kOe) and field (T = 300 K,–20 kOe ≤ H ≤ 20 kOe) dependences of the saturation magnetization of these solid solutions are studied with a vibrating-sample magnetometer.more » The concentration dependences of the Curie temperature T{sub C}, the specific spontaneous magnetization, and the coercive force are plotted. The magnetic parameters are found to decrease with increasing substitution. The microwave properties of the solid solutions are analyzed in an external magnetic field (0 ≤ H ≤ 4 kOe). As the cation Ga{sup 3+} concentration increases from x = 0.1 to 0.6, the natural ferromagnetic resonance (NFMR) frequency decreases; as the concentration increases further to x = 1.2, this frequency again increases. As the cation Ga{sup 3+} concentration increases, the NFMR line width increases, which indicates a widening of the frequency range where electromagnetic radiation is intensely absorbed. Here, the resonance curve peak amplitude changes insignificantly. The shift of the NFMR frequency in an applied magnetic field is more pronounced for samples with low cation Ga{sup 3+} concentrations. The role of diamagnetic substitution is revealed, and the prospects and advantages of Ga-substituted beryllium hexaferrite as the material absorbing high-frequency electromagnetic radiation are demonstrated.« less

Untersuchungen zum Harnsäuremetabolismus von Littorina littorea (Gastropoda)

NASA Astrophysics Data System (ADS)

Heil, K. P.; Eichelberg, D.

1983-12-01

Periwinkles, as typical inhabitants of sea-shores, are subjected to extreme changes of environmental conditions, which affect their excretion. In Littorina littorea uric acid, urea and ammonium were detected particularly in the kidney, but the only metabolite excreted was ammonium. Only the concentration of uric acid was dependent on the availability of water; decreasing periods of submersion during low tide and raised salinities caused a higher concentration of uric acid, while increasing periods of submersion and lowered salinities effected the opposite. Transfer of periwinkles within their intertidal habitat and laboratory experiments to test the effect of salinity showed that the concentration of uric acid in the kidney is adaptable. The dependence of uric acid concentration in the kidney on environmental conditions and the ammoniotelic excretion of L. littorea are discussed with regard to its particular living conditions. It is suggested that uric acid serves as nitrogen depot and has a particular function in osmoregulation.

Architectural and Mechanical Cues Direct Mesenchymal Stem Cell Interactions with Crosslinked Gelatin Scaffolds

PubMed Central

McAndrews, Kathleen M.; Kim, Min Jeong; Lam, Tuyet Y.; McGrail, Daniel J.

2014-01-01

Naturally derived biomaterials have emerged as modulators of cell function and tissue substitutes. Here, we developed crosslinked glutaraldehyde (GTA) scaffolds for the expansion and differentiation of mesenchymal stem cells (MSCs). The mechanical and architectural properties of the scaffolds were altered by varying the concentration of gelatin and GTA. Higher GTA concentrations were associated with an increase in more confined pores and osteogenic differentiation. In addition, myogenic potential varied with crosslinking degree, although bulk mechanical properties were unaltered. Correlation analysis revealed that ALP activity of differentiated MSCs on higher gelatin concentration scaffolds was dependent on traditional effectors, including environment elasticity and spread area. In contrast, the differentiation capacity of cells cultured on lower gelatin concentration scaffolds did not correlate with these factors, instead it was dependent on the hydrated pore structure. These results suggest that scaffold composition can determine what factors direct differentiation and may have critical implications for biomaterial design. PMID:24873687

Kinetics of the monomer-dimer reaction of yeast hexokinase PI.

PubMed

Hoggett, J G; Kellett, G L

1992-10-15

Kinetic studies of the glucose-dependent monomer-dimer reaction of yeast hexokinase PI at pH 8.0 in the presence of 0.1 M-KCl have been carried out using the fluorescence temperature-jump technique. A slow-relaxation effect was observed which was attributed from its dependence on enzyme concentration to the monomer-dimer reaction; the reciprocal relaxation times tau-1 varied from 3 s-1 at low concentrations of glucose to 42 s-1 at saturating concentrations. Rate constants for association (kass.) and dissociation (kdiss.) were determined as a function of glucose concentration using values of the equilibrium association constant of the monomer-dimer reaction derived from sedimentation ultracentrifugation studies under similar conditions, and also from the dependence of tau-2 on enzyme concentration. kass. was almost independent of glucose concentration and its value (2 x 10(5) M-1.s-1) was close to that expected for a diffusion-controlled process. The influence of glucose on the monomer-dimer reaction is entirely due to effects on kdiss., which increases from 0.21 s-1 in the absence of glucose to 25 s-1 at saturating concentrations. The monomer and dimer forms of hexokinase have different affinities and Km values for glucose, and the results reported here imply that there may be a significant lag in the response of the monomer-dimer reaction to changes in glucose concentrations in vivo with consequent hysteretic effects on the hexokinase activity.

Kinetics of the monomer-dimer reaction of yeast hexokinase PI.

PubMed Central

Hoggett, J G; Kellett, G L

1992-01-01

Kinetic studies of the glucose-dependent monomer-dimer reaction of yeast hexokinase PI at pH 8.0 in the presence of 0.1 M-KCl have been carried out using the fluorescence temperature-jump technique. A slow-relaxation effect was observed which was attributed from its dependence on enzyme concentration to the monomer-dimer reaction; the reciprocal relaxation times tau-1 varied from 3 s-1 at low concentrations of glucose to 42 s-1 at saturating concentrations. Rate constants for association (kass.) and dissociation (kdiss.) were determined as a function of glucose concentration using values of the equilibrium association constant of the monomer-dimer reaction derived from sedimentation ultracentrifugation studies under similar conditions, and also from the dependence of tau-2 on enzyme concentration. kass. was almost independent of glucose concentration and its value (2 x 10(5) M-1.s-1) was close to that expected for a diffusion-controlled process. The influence of glucose on the monomer-dimer reaction is entirely due to effects on kdiss., which increases from 0.21 s-1 in the absence of glucose to 25 s-1 at saturating concentrations. The monomer and dimer forms of hexokinase have different affinities and Km values for glucose, and the results reported here imply that there may be a significant lag in the response of the monomer-dimer reaction to changes in glucose concentrations in vivo with consequent hysteretic effects on the hexokinase activity. Images Fig. 1. PMID:1445216

Protective Effects of Maillard Reaction Products of Whey Protein Concentrate against Oxidative Stress through an Nrf2-Dependent Pathway in HepG2 Cells.

PubMed

Pyo, Min Cheol; Yang, Sung-Yong; Chun, Su-Hyun; Oh, Nam Su; Lee, Kwang-Won

2016-09-01

Whey protein concentrate (WPC), which contains α-lactalbumin and β-lactoglobulin, is utilized widely in the food industry. The Maillard reaction is a complex reaction that produces Maillard reaction products (MRPs), which are associated with the formation of antioxidant compounds. In this study, the hepatoprotection activity of MRPs of WPC against oxidative stress through the nuclear factor-E2-related factor 2 (Nrf2)-dependent antioxidant pathway in HepG2 cells was examined. Glucose-whey protein concentrate conjugate (Glc-WPC) was obtained from Maillard reaction between WPC and glucose. The fluorescence intensity of Glc-WPC increased after 7 d compared to native WPC, and resulted in loss of 48% of the free amino groups of WPC. The sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) patterns of Glc-WPC showed the presence of a high-molecular-weight portion. Treatment of HepG2 cells with Glc-WPC increased cell viability in the presence of oxidative stress, inhibited the generation of intracellular reactive oxygen species by tert-butyl hydroperoxide (t-BHP), and increased the glutathione level. Nrf2 translocation and Nrf2, reduced nicotinamide adenine dinucleotide phosphate (NAD(P)H)-quinone oxidoreductase 1 (NOQ1), heme oxygenase-1 (HO-1), glutamate-L-cysteine ligase (GCL)M and GCLC mRNA levels were increased by Glc-WPC. Also, Glc-WPC increased the phosphorylation of extracellular signal-regulated kinase (ERK) 1/2 and c-Jun N-terminal kinase (JNK). The results of this study demonstrate that Glc-WPC activates the Nrf2-dependent pathway through the phosphorylation of ERK1/2 and JNK in HepG2 cells, and induces production of antioxidant enzymes and phase II enzymes.

The Relationship of Mucus Concentration (Hydration) to Mucus Osmotic Pressure and Transport in Chronic Bronchitis

PubMed Central

Coakley, Raymond D.; Button, Brian; Henderson, Ashley G.; Zeman, Kirby L.; Alexis, Neil E.; Peden, David B.; Lazarowski, Eduardo R.; Davis, C. William; Bailey, Summer; Fuller, Fred; Almond, Martha; Qaqish, Bahjat; Bordonali, Elena; Rubinstein, Michael; Bennett, William D.; Kesimer, Mehmet; Boucher, Richard C.

2015-01-01

Rationale: Chronic bronchitis (CB) is characterized by persistent cough and sputum production. Studies were performed to test whether mucus hyperconcentration and increased partial osmotic pressure, in part caused by abnormal purine nucleotide regulation of ion transport, contribute to the pathogenesis of CB. Objectives: We tested the hypothesis that CB is characterized by mucus hyperconcentration, increased mucus partial osmotic pressures, and reduced mucus clearance. Methods: We measured in subjects with CB as compared with normal and asymptomatic smoking control subjects indices of mucus concentration (hydration; i.e., percentage solids) and sputum adenine nucleotide/nucleoside concentrations. In addition, sputum partial osmotic pressures and mucus transport rates were measured in subjects with CB. Measurements and Results: CB secretions were hyperconcentrated as indexed by an increase in percentage solids and total mucins, in part reflecting decreased extracellular nucleotide/nucleoside concentrations. CB mucus generated concentration-dependent increases in partial osmotic pressures into ranges predicted to reduce mucus transport. Mucociliary clearance (MCC) in subjects with CB was negatively correlated with mucus concentration (percentage solids). As a test of relationships between mucus concentration and disease, mucus concentrations and MCC were compared with FEV1, and both were significantly correlated. Conclusions: Abnormal regulation of airway surface hydration may slow MCC in CB and contribute to disease pathogenesis. PMID:25909230

Effects of climate change and seed dispersal on airborne ragweed pollen loads in Europe

NASA Astrophysics Data System (ADS)

Hamaoui-Laguel, Lynda; Vautard, Robert; Liu, Li; Solmon, Fabien; Viovy, Nicolas; Khvorostyanov, Dmitry; Essl, Franz; Chuine, Isabelle; Colette, Augustin; Semenov, Mikhail A.; Schaffhauser, Alice; Storkey, Jonathan; Thibaudon, Michel; Epstein, Michelle M.

2015-08-01

Common ragweed (Ambrosia artemisiifolia) is an invasive alien species in Europe producing pollen that causes severe allergic disease in susceptible individuals. Ragweed plants could further invade European land with climate and land-use changes. However, airborne pollen evolution depends not only on plant invasion, but also on pollen production, release and atmospheric dispersion changes. To predict the effect of climate and land-use changes on airborne pollen concentrations, we used two comprehensive modelling frameworks accounting for all these factors under high-end and moderate climate and land-use change scenarios. We estimate that by 2050 airborne ragweed pollen concentrations will be about 4 times higher than they are now, with a range of uncertainty from 2 to 12 largely depending on the seed dispersal rate assumptions. About a third of the airborne pollen increase is due to on-going seed dispersal, irrespective of climate change. The remaining two-thirds are related to climate and land-use changes that will extend ragweed habitat suitability in northern and eastern Europe and increase pollen production in established ragweed areas owing to increasing CO2. Therefore, climate change and ragweed seed dispersal in current and future suitable areas will increase airborne pollen concentrations, which may consequently heighten the incidence and prevalence of ragweed allergy.

Effect of neodymium substitution on the electric and dielectric properties of Mn-Ni-Zn ferrite

NASA Astrophysics Data System (ADS)

Agami, W. R.

2018-04-01

Ferrite samples of Mn0.5Ni0.1Zn0.4NdxFe2-xO4 (x = 0.0, 0.01, 0.02, 0.05, 0.075 and 0.1) have been prepared by usual ceramic method. The temperature and composition dependences of the dc electric resistivity (ρdc) were studied. The frequency and composition dependences of the ac electric resistivity (ρac) and dielectric parameters (dielectric constant ε' and dielectric loss ε'') have been investigated. ρdc was found to decrease with temperature for all samples while it increases with increasing Nd3+ concentration. On the other hand, ρac and the dielectric properties were found to decrease with increasing the frequency while ρac increases and both ε' and ε'' decrease with increasing Nd3+ concentration. These results were explained by the Maxwell-Wagner two-layer model and Koops's theory. The improvement in dc and ac electric resistivities shows that these prepared materials are valid for decreasing the eddy current losses at high frequencies, so they can be used in the fabrication of multilayer chip inductor (MLCI) devices.

Structural characterization of a magnetic granular system under a time-dependent magnetic field: Voronoi tessellation and multifractal analysis

NASA Astrophysics Data System (ADS)

Moctezuma, R. E.; Arauz-Lara, J. L.; Donado, F.

2018-04-01

The structure of a two-dimensional magnetic granular system was determined by multifractal and Voronoi polygon analysis for a wide range of particle concentrations. Randomizing of the particle motions are produced by applying to the system a time-dependent sinusoidal magnetic field directed along the vertical direction. Both repulsive and attractive short-range interactions between the particles are induced. A direct observation of such system shows qualitatively that, as particle concentration increases, the structure evolves from being liquid-like at low particle concentrations to solid-like at high concentrations. We observe the formation of clusters which are small and weakly bonded and short-lived at low concentrations. Above a threshold particle concentration, clusters grow larger and are more strongly attached. In the system, one can distinguish the mobile particles from the immobile particles belonging to clusters, they can be considered separately as two different phases, a fluid and a solid. We determined the information entropy of the system as a whole and separately from each phase as particle concentration increases. The distribution of the Voronoi polygon areas are well fitted by a two-parameter gamma distribution and we have found that the regularity factor shows a notable change when pieces of the solid phase start to form. The methods we use here show that they can use even when the system is heterogeneous and they provide information when changes start.

In vitro functional interactions of acetylcholine esterase inhibitors and muscarinic receptor antagonists in the urinary bladder of the rat.

PubMed

Killi, Uday K; Wsol, Vladimir; Soukup, Ondrej; Kuca, Kamil; Winder, Michael; Tobin, Gunnar

2014-02-01

Obidoxime, a weak acetylcholine-esterase (AChE) inhibitor, exerts muscarinic receptor antagonism with a significant muscarinic M2 receptor selective profile. The current examinations aimed to determine the functional significance of muscarinic M2 receptors in the state of AChE inhibition, elucidating muscarinic M2 and M3 receptor interaction. In the in vitro examinations, methacholine evoked concentration-dependent bladder contractile and atrial frequency inhibitory responses. Although atropine abolished both, methoctramine (1 μmol/L) only affected the cholinergic response in the atrial preparations. However, in the presence of methoctramine, physostigmine, an AChE inhibitor, increased the basal tension of the bladder strip preparations (+68%), as well as the contractile responses to low concentrations of methacholine (< 5 μmol/L; +90-290%). In contrast to physostigmine, obidoxime alone raised the basal tension (+58%) and the responses to low concentrations of methacholine (< 5 μmol/L; +80-450%). Physostigmine concentration-dependently increased methacholine-evoked responses, similarly to obidoxime at low concentrations. However, at large concentrations (> 5 μmol/L), obidoxime, because of its unselective muscarinic receptor antagonism, inhibited the methacholine bladder responses. In conclusion, the current results show that muscarinic M2 receptors inhibit muscarinic M3 receptor-evoked contractile responses to low concentrations of acetylcholine in the synaptic cleft. The muscarinic M2 and M3 receptor crosstalk could be a counteracting mechanism in the treatment of AChE inhibition when using reactivators, such as obidoxime. © 2013 Wiley Publishing Asia Pty Ltd.

MRP2 mediated drug-drug interaction: indomethacin increases sulfasalazine absorption in the small intestine, potentially decreasing its colonic targeting.

PubMed

Dahan, Arik; Amidon, Gordon L

2010-02-15

We have recently shown that efflux transport, mediated by multidrug resistance-associated protein 2 (MRP2) and breast cancer resistance protein (BCRP), is responsible for sulfasalazine low-permeability in the small intestine, thereby enabling its colonic targeting and therapeutic action. The purpose of the present study was to evaluate the potential pharmacokinetic interaction between indomethacin and sulfasalazine, in the mechanism of efflux transporter competition. The concentration-dependent effects of indomethacin on sulfasalazine intestinal epithelial transport were investigated across Caco-2 cell monolayers, in both apical to basolateral (AP-BL) and BL-AP directions. The interaction was then investigated in the in situ single-pass rat jejunal perfusion model. Sulfasalazine displayed 30-fold higher BL-AP than AP-BL Caco-2 permeability, indicative of net mucosal secretion. Indomethacin significantly increased AP-BL and decreased BL-AP sulfasalazine Caco-2 transport, in a concentration-dependent manner, with IC(50) values of 75 and 196 microM respectively. In the rat model, higher sulfasalazine concentrations resulted in higher intestinal permeability, consistent with saturation of efflux transporter. Without indomethacin, sulfasalazine demonstrated low rat jejunal permeability (vs. metoprolol). Indomethacin significantly increased sulfasalazine P(eff), effectively shifting it from BCS (biopharmaceutics classification system) Class IV to II. In conclusion, the data indicate that concomitant intake of indomethacin and sulfasalazine may lead to increased absorption of sulfasalazine in the small intestine, thereby reducing its colonic concentration and potentially altering its therapeutic effect. Copyright 2009 Elsevier B.V. All rights reserved.

[Role of calcium ions in the mechanism of action of acetylcholine on energy metabolism in rat liver mitochondria].

PubMed

Vatamaniuk, M Z; Artym, V V; Kuka, O B; Doliba, M M; Shostakovs'ka, I V

1996-01-01

It is shown that administration of acetylcholine to animals (50 micrograms per 100 g of body weight) leads to the activation of respiration and oxidative phosphorylation in the rat liver mitochondria under oxidation of alpha-ketoglutarate; this effect depends on the concentration of calcium ions in the incubation medium of mitochondria. The rate of ADP-stimulated respiration of mitochondria of experimental animals reaches its maximum level under lower concentrations of Ca2+ than in the control animals. The results of investigation of dependence of acetyl choline effect on respiration of mitochondria on the concentration of alpha-ketoglutarate in calcium and calcium-free incubation medium have shown that the half-maximum effect of acetylcholine is observed in calcium medium at lower concentration of the substrate than in calcium-free medium. The latter indicates to the increase of affinity of alpha-ketoglutarate dehydrogenase to alpha-ketoglutarate under these conditions. It is found out that acetylcholine (1.10(-8) M) increases the rate of ADP- and Ca(2+)-stimulated respiration of mitochondria of isolated perfused rat liver, while mutual effect of verapamyl and niphedipin removes this effect.

Synaptic excitation mediated by AMPA receptors in rat cerebellar slices is selectively enhanced by aniracetam and cyclothiazide.

PubMed

Boxall, A R; Garthwaite, J

1995-05-01

AMPA receptors mediate fast, glutamatergic synaptic transmission in the central nervous system. The time-course of the associated postsynaptic current has been suggested to be determined principally by the kinetics of glutamate binding and receptor desensitization. Aniracetam and cyclothiazide are drugs capable of selectively preventing desensitization of the AMPA receptor. To investigate the relevance of desensitization to fast synaptic transmission in the cerebellum we have tested these compounds against AMPA-induced depolarizations and postsynaptic potentials using the grease-gap recording technique. Aniracetam (1 microM-5 mM) and cyclothiazide (1 microM-500 microM) both enhanced the depolarising action of AMPA (1 microM) on Purkinje cells in a concentration-dependent manner. At the highest concentrations tested, the increases over controls were approximately 600% and 800% respectively. Aniracetam also increased, in a concentration-dependent manner, the amplitude of the evoked synaptic potentials of both parallel fibre-Purkinje cell and mossy fibre-granule cell pathways, with the highest concentrations tested enhancing the potentials by approximately 60% and 75% respectively. These data suggest that, at two different synapses in the cerebellum, AMPA receptor desensitization occurs physiologically and is likely to contribute to the shape of fast synaptic currents.

Ion selectivity of the Vibrio alginolyticus flagellar motor.

PubMed Central

Liu, J Z; Dapice, M; Khan, S

1990-01-01

The marine bacterium, Vibrio alginolyticus, normally requires sodium for motility. We found that lithium will substitute for sodium. In neutral pH buffers, the membrane potential and swimming speed of glycolyzing bacteria reached maximal values as sodium or lithium concentration was increased. While the maximal potentials obtained in the two cations were comparable, the maximal swimming speed was substantially lower in lithium. Over a wide range of sodium concentration, the bacteria maintained an invariant sodium electrochemical potential as determined by membrane potential and intracellular sodium measurements. Over this range the increase of swimming speed took Michaelis-Menten form. Artificial energization of swimming motility required imposition of a voltage difference in concert with a sodium pulse. The cation selectivity and concentration dependence exhibited by the motile apparatus depended on the viscosity of the medium. In high-viscosity media, swimming speeds were relatively independent of either ion type or concentration. These facts parallel and extend observations of the swimming behavior of bacteria propelled by proton-powered flagella. In particular, they show that ion transfers limit unloaded motor speed in this bacterium and imply that the coupling between ion transfers and force generation must be fairly tight. PMID:2394685

Optical transitions in GaNAs quantum wells with variable nitrogen content embedded in AlGaAs

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

Elborg, M., E-mail: ELBORG.Martin@nims.go.jp; Noda, T.; Mano, T.

2016-06-15

We investigate the optical transitions of GaN{sub x}As{sub 1−x} quantum wells (QWs) embedded in wider band gap AlGaAs. A combination of absorption and emission spectroscopic techniques is employed to systematically investigate the properties of GaNAs QWs with N concentrations ranging from 0 – 3%. From measurement of the photocurrent spectra, we find that besides QW ground state and first excited transition, distinct increases in photocurrent generation are observed. Their origin can be explained by N-induced modifications in the density of states at higher energies above the QW ground state. Photoluminescence experiments reveal that peak position dependence with temperature changes withmore » N concentration. The characteristic S-shaped dependence for low N concentrations of 0.5% changes with increasing N concentration where the low temperature red-shift of the S-shape gradually disappears. This change indicates a gradual transition from impurity picture, where localized N induced energy states are present, to alloying picture, where an impurity-band is formed. In the highest-N sample, photoluminescence emission shows remarkable temperature stability. This phenomenon is explained by the interplay of N-induced energy states and QW confined states.« less

Aerosols emitted in underground mine air by diesel engine fueled with biodiesel.

PubMed

Bugarski, Aleksandar D; Cauda, Emanuele G; Janisko, Samuel J; Hummer, Jon A; Patts, Larry D

2010-02-01

Using biodiesel in place of petroleum diesel is considered by several underground metal and nonmetal mine operators to be a viable strategy for reducing the exposure of miners to diesel particulate matter. This study was conducted in an underground experimental mine to evaluate the effects of soy methyl ester biodiesel on the concentrations and size distributions of diesel aerosols and nitric oxides in mine air. The objective was to compare the effects of neat and blended biodiesel fuels with those of ultralow sulfur petroleum diesel. The evaluation was performed using a mechanically controlled, naturally aspirated diesel engine equipped with a muffler and a diesel oxidation catalyst. The effects of biodiesel fuels on size distributions and number and total aerosol mass concentrations were found to be strongly dependent on engine operating conditions. When fueled with biodiesel fuels, the engine contributed less to elemental carbon concentrations for all engine operating modes and exhaust configurations. The substantial increases in number concentrations and fraction of organic carbon (OC) in total carbon over the baseline were observed when the engine was fueled with biodiesel fuels and operated at light-load operating conditions. Size distributions for all test conditions were found to be single modal and strongly affected by engine operating conditions, fuel type, and exhaust configuration. The peak and total number concentrations as well as median diameter decreased with an increase in the fraction of biodiesel in the fuels, particularly for high-load operating conditions. The effects of the diesel oxidation catalyst, commonly deployed to counteract the potential increase in OC emissions due to use of biodiesel, were found to vary depending upon fuel formulation and engine operating conditions. The catalyst was relatively effective in reducing aerosol number and mass concentrations, particularly at light-load conditions, but also showed the potential for an increase in nitrogen dioxide concentrations at high-load modes.

Role of Lon, an ATP-Dependent Protease Homolog, in Resistance of Pseudomonas aeruginosa to Ciprofloxacin▿

PubMed Central

Brazas, Michelle D.; Breidenstein, Elena B. M.; Overhage, Joerg; Hancock, Robert E. W.

2007-01-01

With few novel antimicrobials in the pharmaceutical pipeline, resistance to the current selection of antibiotics represents a significant therapeutic challenge. Microbial persistence in subinhibitory antibiotic environments has been proposed to contribute to the development of resistance. Pseudomonas aeruginosa cultures pretreated with subinhibitory concentrations of ciprofloxacin were found to exhibit an adaptive resistance phenotype when cultures were subsequently exposed to suprainhibitory ciprofloxacin concentrations. Microarray experiments revealed candidate genes involved in such adaptive resistance. Screening of 10,000 Tn5-luxCDABE mutants identified several mutants with increased or decreased ciprofloxacin susceptibilities, including mutants in PA1803, a close homolog of the ATP-dependent lon protease, which were found to exhibit ≥4-fold-increased susceptibilities to ciprofloxacin and other fluoroquinolones, but not to gentamicin or imipenem, as well as a characteristic elongated morphology. Complementation of the lon mutant restored wild-type antibiotic susceptibility and cell morphology. Expression of the lon mutant, as monitored through a luciferase reporter fusion, was found to increase over time in the presence of subinhibitory ciprofloxacin concentrations. The data are consistent with the hypothesis that the induction of Lon by ciprofloxacin is involved in adaptive resistance. PMID:17893152

Biogas properties and enzymatic analysis during anaerobic fermentation of Phragmites australis straw and cow dung: influence of nickel chloride supplement.

PubMed

Tian, Yonglan; Zhang, Huayong; Chai, Yang; Wang, Lijun; Mi, Xueyue; Zhang, Luyi; Ware, Maxwell Adam

2017-02-01

The importance of nickel (added as NiCl 2 ) on mesophilic anaerobic fermentation of Phragmites australis straw and cow dung was demonstrated by investigating the biogas properties, pH values, organic matter degradation [chemical oxygen demand (COD)] and enzyme activities (cellulase, protease and dehydrogenase) during the fermentation process. The results showed that Ni 2+ addition increased the cumulative biogas yields by >18 % by improving the efficiency of first peak stage and bringing forward the second peak stage. The pH values were not significantly influenced by Ni 2+ addition (p > 0.05). Biogas yields were associated with variations in COD concentrations rather than momentary concentrations. At the start-up stage of fermentation (4th day), the biogas yields increased gradually together with the increase of dehydrogenase activities at elevated Ni 2+ concentrations when cellulase and protease activities were similar in all test groups. It is suggested that Ni 2+ addition was mainly dependent on the methanogenic stage. After the start-up stage, the impact of Ni 2+ addition on biogas production was mainly dependent on its effect on cellulase activities, rather than protease or dehydrogenase activities.

Thermodynamic properties and diffusion of water + methane binary mixtures

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

Shvab, I.; Sadus, Richard J., E-mail: rsadus@swin.edu.au

2014-03-14

Thermodynamic and diffusion properties of water + methane mixtures in a single liquid phase are studied using NVT molecular dynamics. An extensive comparison is reported for the thermal pressure coefficient, compressibilities, expansion coefficients, heat capacities, Joule-Thomson coefficient, zero frequency speed of sound, and diffusion coefficient at methane concentrations up to 15% in the temperature range of 298–650 K. The simulations reveal a complex concentration dependence of the thermodynamic properties of water + methane mixtures. The compressibilities, heat capacities, and diffusion coefficients decrease with increasing methane concentration, whereas values of the thermal expansion coefficients and speed of sound increase. Increasing methanemore » concentration considerably retards the self-diffusion of both water and methane in the mixture. These effects are caused by changes in hydrogen bond network, solvation shell structure, and dynamics of water molecules induced by the solvation of methane at constant volume conditions.« less

Substrate misorientation induced strong increase in the hole concentration in Mg doped GaN grown by metalorganic vapor phase epitaxy

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

Suski, T.; Litwin-Staszewska, E.; Piotrzkowski, R.

We demonstrate that relatively small GaN substrate misorientation can strongly change hole carrier concentration in Mg doped GaN layers grown by metalorganic vapor phase epitaxy. In this work intentionally misoriented GaN substrates (up to 2 deg. with respect to ideal <0001> plane) were employed. An increase in the hole carrier concentration to the level above 10{sup 18} cm{sup -3} and a decrease in GaN:Mg resistivity below 1 {omega} cm were achieved. Using secondary ion mass spectroscopy we found that Mg incorporation does not change with varying misorientation angle. This finding suggests that the compensation rate, i.e., a decrease in unintentionalmore » donor density, is responsible for the observed increase in the hole concentration. Analysis of the temperature dependence of electrical transport confirms this interpretation.« less

Boron removal in radioactive liquid waste by forward osmosis membrane

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

Doo Seong Hwang; Hei Min Choi; Kune Woo Lee

2013-07-01

This study investigated the treatment of boric acid contained in liquid radioactive waste using a forward osmosis membrane. The boron permeation through the membrane depends on the type of membrane, membrane orientation, pH of the feed solution, salt and boron concentration in the feed solution, and osmotic pressure of the draw solution. The boron flux begins to decline from pH 7 and increases with an increase of the osmotic driving force. The boron flux decreases slightly with the salt concentration, but is not heavily influenced by a low salt concentration. The boron flux increases linearly with the concentration of boron.more » No element except for boron was permeated through the FO membrane in the multi-component system. The maximum boron flux is obtained in an active layer facing a draw solution orientation of the CTA-ES membrane under conditions of less than pH 7 and high osmotic pressure. (authors)« less

Kinetic properties of the sodium-calcium exchanger in rat brain synaptosomes.

PubMed Central

Fontana, G; Rogowski, R S; Blaustein, M P

1995-01-01

1. The kinetic properties of the internal Na+ (Na+i)- dependent 45Ca2+ influx and external Na+ (Na+o)-dependent 45Ca2+ efflux were determined in isolated rat brain nerve terminals (synaptosomes) under conditions which the concentrations of internal Na+ ([Na+]i), external Na+ ([Na+]o), external Ca2+ (Ca2+]o), and external K+ ([K+]o) were varied. Both fluxes are manifestations of Na(+)-Ca2+ exchange. 2. Ca2+ uptake was augmented by raising [Na+]i and / or lowering [Na+]o. The increase in Ca2+ uptake induced by removing external Na+ was, in most instances, quantitatively equal to the Na+i-dependent Ca2+ uptake. 3. The Na+i-dependent Ca2+ uptake (measured at 1 s) was activated with an apparent half-maximal [Ca2+]o (KCa(o)) of about 0.23 mM. External Na+ inhibited the uptake in a non- competitive manner: increasing [Na+]o from 4.7 to 96 mM reduced the maximal Na+(i)-dependent Ca2+ uptake but did not affect KCa(o). 4. The inhibition of Ca2+ uptake by Na+o was proportional to ([Na+]o)2, and had a Hill coefficient (nH) of approximately 2.0. The mean apparent half-maximal [Na+]o for inhibition (KI(Na)) was about 60mM, and was independent of [Ca2+]o between 0.1 and 1.2mM; this, too, is indicative of non-competitive inhibition. 5. Low concentrations of alkali metal ions (M+) in the medium, including Na+, stimulated the Na+i-dependent uptake. The external Na+ and K+ concentrations required for apparent half-maximal activation (KM(Na) and KM(K), respectively) were 0.12 and 0.10mM. Thus, the relationship between Ca2+ uptake and [Na+]o was biphasic: uptake was stimulated by [Na+]o < or = 10 mM, and inhibited by higher [Na+]o. 6. The calculated maximal Na+i-dependent Ca2+ uptake (Jmax) was about 1530 pmol (mg protein) -1s-1 at 30 degrees C saturating [Ca2+]o and external M+ concentration ([M+]o), and with negligible inhibition by external Na+. 7. Internal Na+ activated the Ca2+ uptake with an apparent half-maximal concentration (KNa(i)) of about 20 mM and a Hill coefficient, nH, of approximately 3.0. 8. The Jmax for the Na+o-dependent efflux of Ca2+ from 45Ca(2+)-loaded synaptosomes treated with carbonyl cyanide p-trifluormethoxy-phenylhydrazone (FCCP) and caffeine (to release stored Ca2+ and raise the internal Ca2+ concentration ([Ca2+]i) was about 1800-2000 pmol (mg protein -1s-1 at 37 degrees C. 9. When the membrane potential (Vm) was reduced (depolarized) by increasing [K+]o, the Na+i-dependent Ca2+ influx increased, and the Na+o-dependent Ca2+ efflux declined. Both fluxes changed about 2-fold per 60 mV change in Vm. This voltage sensitivity corresponds to the movement of one elementary charge through about 60% of the membrane electric field. The symmetry suggests that the voltage-sensitive step is reversible. 10. The Jmax values for both Ca2P influx and efflux correspond to a Na+-Ca2+ exchange-mediated flux of about 425-575 jumol Ca2P (1 cell water)-' s-' or a turnover of about one quarter of the total synaptosome Ca2P in 1 s. We conclude that the Na+-Ca2P exchanger may contribute to Ca2P entry during nerve terminal depolarization; it is likely to be a major mechanism mediating Ca2P extrusion during subsequent repolarization and recovery. PMID:7666363

In vitro study of the effect of three hydrogen peroxide concentrations on the corrosion behavior and surface topography of alumina-reinforced dental ceramic.

PubMed

Abu-Eittah, Manal R; Mandour, Mona H

2011-10-01

This in vitro investigation studied the effect of three hydrogen peroxide (HP) concentrations (30%, 35%, 38% v/v) at two time intervals (1 and 2 hours) on the corrosion behavior and surface topography of a dental ceramic. A total of 62 Vitadur Alpha discs were constructed following manufacturer instructions. Specimens were divided into four main groups (n = 8). Group 1 (control): specimens were immersed in 4% acetic acid for 18 hours at 80°C. Groups 2, 3, and 4: specimens were immersed in 30%, 35%, and 38% HP concentrations, respectively. Each of the three groups was divided into two subgroups (a and b) according to the immersion time (1 and 2 hours, respectively). Specimens of subgroup a were further immersed in 4% acetic acid for 18 hours at 80°C and were designated as subgroup c. The corrosion behavior of the ceramic specimens were tested by solution analysis using the atomic absorption method, weight loss percent, and corrosion rate. Surface topography was investigated by surface roughness (Ra) measurements and scanning electron microscopy (SEM). Results were statistically analyzed. There was a significant increase for ions leached with the increase in time of immersion for all ions at 35% and 38% HP, while at 30% HP, ions of K(+) , Al(3+) , and Si(4+) did not increase significantly with time. The results also showed that at a fixed time of immersion, all ions released were dependent on the increase of HP concentration except for Al(3+) ions (p < 0.05). The combined treatment of specimens with HP followed by acetic acid had a significant effect on the increase of ions leached (p < 0.05). The surface roughness values for all specimens increased significantly with time of immersion as well as with the increase in concentration of HP (p < 0.05). These results were confirmed with SEM. The amount of released ions is directly proportional to HP concentration and time of immersion. Specimens exposed to both HP and acetic acid showed increased weight loss and a higher corrosion rate than those exposed to acetic acid only. Surface roughness values were time and HP concentration dependent. © 2011 by The American College of Prosthodontists.

Adsorption of Ten Microcystin Congeners to Common Laboratory-Ware Is Solvent and Surface Dependent.

PubMed

Altaner, Stefan; Puddick, Jonathan; Wood, Susanna A; Dietrich, Daniel R

2017-04-06

Cyanobacteria can produce heptapetides called microcystins (MC) which are harmful to humans due to their ability to inhibit cellular protein phosphatases. Quantitation of these toxins can be hampered by their adsorption to common laboratory-ware during sample processing and analysis. Because of their structural diversity (>100 congeners) and different physico-chemical properties, they vary in their adsorption to surfaces. In this study, the adsorption of ten different MC congeners (encompassing non-arginated to doubly-arginated congeners) to common laboratory-ware was assessed using different solvent combinations. Sample handling steps were mimicked with glass and polypropylene pipettes and vials with increasing methanol concentrations at two pH levels, before analysis by liquid chromatography-tandem mass spectrometry. We demonstrated that MC adsorb to polypropylene surfaces irrespective of pH. After eight successive pipet actions using polypropylene tips ca. 20% of the MC were lost to the surface material, which increased to 25%-40% when solutions were acidified. The observed loss was alleviated by changing the methanol (MeOH) concentration in the final solvent. The required MeOH concentration varied depending on which congener was present. Microcystins only adsorbed to glass pipettes (loss up to 30% after eight pipet actions) when in acidified aqueous solutions. The latter appeared largely dependent on the presence of ionizable groups, such as arginine residues.

Anaesthetic modulation of nicotinic ion channel kinetics in bovine chromaffin cells.

PubMed Central

Charlesworth, P; Richards, C D

1995-01-01

1. We have investigated the action of the anaesthetics methoxyflurane, methohexitone and etomidate on the nicotinic acetylcholine receptor channel of bovine adrenal chromaffin cells using the whole cell patch clamp technique. 2. Spectral analysis of macroscopic currents evoked by 25 microM carbachol revealed that each of the agents tested reduced the lifetime of the channel open state in a dose-dependent manner. The whole cell current was inhibited in a concentration-dependent fashion by each agent. 3. Channel gating parameters were calculated from single channel studies and the results used to test models explaining the modulation of nicotinic acetylcholine receptor channels by anaesthetics. 4. Each of the agents studied reduced the mean channel open time in a concentration-dependent manner. Anaesthetic concentrations reducing mean open time by 50% were: 370 microM methoxyflurane, 30 microM methohexitone or 23 microM etomidate. 5. Methohexitone and etomidate produced an increase in the number of brief closures within bursts, while no such increase was observed with methoxyflurane. Despite these inter-burst gaps, mean burst length was reduced by each of the agents tested. 6. It is concluded that a simple sequential blocking model fails to account for the action of these anaesthetics. An extended model, in which blocked channels can close, may be applicable. PMID:7773553

Multi-walled carbon nanotubes (NM401) induce ROS-mediated HPRT mutations in Chinese hamster lung fibroblasts

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

Rubio, Laura; El Yamani, Naouale; Kazimirova, Alena

Although there is an important set of data showing potential genotoxic effects of nanomaterials (NMs) at the DNA (comet assay) and chromosome (micronucleus test) levels, few studies have been conducted to analyze their potential mutagenic effects at gene level. We have determined the ability of multi-walled carbon nanotubes (MWCNT, NM401), to induce mutations in the HPRT gene in Chinese hamster lung (V79) fibroblasts. NM401, characterized in the EU NanoGenotox project, were further studied within the EU Framework Programme Seven (FP7) project NANoREG. From the proliferation assay data we selected a dose-range of 0.12 to 12 µg/cm{sup 2} At these rangemore » we have been able to observe significant cellular uptake of MWCNT by using transmission electron microscopy (TEM), as well as a concentration-dependent induction of intracellular reactive oxygen species. In addition, a clear concentration-dependent increase in the induction of HPRT mutations was also observed. Data support a potential genotoxic/ carcinogenic risk associated with MWCNT exposure. - Highlights: • MWCNT were tested in V79 cells. • Cellular uptake of MWCNT was detected using TEM. • Intracellular ROS induction was observed after MWCNT exposure. • MWCNT induced a concentration-dependent increase of HPRT mutations.« less

Thermal conductivity of electron-irradiated graphene

NASA Astrophysics Data System (ADS)

Weerasinghe, Asanka; Ramasubramaniam, Ashwin; Maroudas, Dimitrios

2017-10-01

We report results of a systematic analysis of thermal transport in electron-irradiated, including irradiation-induced amorphous, graphene sheets based on nonequilibrium molecular-dynamics simulations. We focus on the dependence of the thermal conductivity, k, of the irradiated graphene sheets on the inserted irradiation defect density, c, as well as the extent of defect passivation with hydrogen atoms. While the thermal conductivity of irradiated graphene decreases precipitously from that of pristine graphene, k0, upon introducing a low vacancy concentration, c < 1%, in the graphene lattice, further reduction of the thermal conductivity with the increasing vacancy concentration exhibits a weaker dependence on c until the amorphization threshold. Beyond the onset of amorphization, the dependence of thermal conductivity on the vacancy concentration becomes significantly weaker, and k practically reaches a plateau value. Throughout the range of c and at all hydrogenation levels examined, the correlation k = k0(1 + αc)-1 gives an excellent description of the simulation results. The value of the coefficient α captures the overall strength of the numerous phonon scattering centers in the irradiated graphene sheets, which include monovacancies, vacancy clusters, carbon ring reconstructions, disorder, and a rough nonplanar sheet morphology. Hydrogen passivation increases the value of α, but the effect becomes very minor beyond the amorphization threshold.

The biodegradation of cable oil components: impact of oil concentration, nutrient addition and bioaugmentation.

PubMed

Towell, Marcie G; Paton, Graeme I; Semple, Kirk T

2011-12-01

The effect of cable oil concentration, nutrient amendment and bioaugmentation on cable oil component biodegradation in a pristine agricultural soil was investigated. Biodegradation potential was evaluated over 21 d by measuring cumulative CO(2) respiration on a Micro-Oxymax respirometer and (14)C-phenyldodecane mineralisation using a (14)C-respirometric assay. Cable oil concentration had a significant effect upon oil biodegradation. Microbial respiratory activity increased with increasing cable oil concentration, whereas (14)C-phenydodecane mineralisation decreased. Bioaugmentation achieved the best cable oil biodegradation performance, resulting in increases in cumulative CO(2) respiration, and maximum rates and extents of (14)C-phenyldodecane mineralisation. Generally, nutrient amendment also enhanced cable oil biodegradation, but not to the extent that degrader amendment did. Cable oil biodegradation was a function of (i) cable oil concentration and (ii) catabolic ability of microbial populations. Bioaugmentation may enhance cable oil biodegradation, and is dependent upon composition, cell number and application of catabolic inocula to soil. Copyright © 2011 Elsevier Ltd. All rights reserved.

DRG axon elongation and growth cone collapse rate induced by Sema3A are differently dependent on NGF concentration.

PubMed

Kaselis, Andrius; Treinys, Rimantas; Vosyliūtė, Rūta; Šatkauskas, Saulius

2014-03-01

Regeneration of embryonic and adult dorsal root ganglion (DRG) sensory axons is highly impeded when they encounter neuronal growth cone-collapsing factor semaphorin3A (Sema3A). On the other hand, increasing evidence shows that DRG axon's regeneration can be stimulated by nerve growth factor (NGF). In this study, we aimed to evaluate whether increased NGF concentrations can counterweight Sema3A-induced inhibitory responses in 15-day-old mouse embryo (E15) DRG axons. The DRG explants were grown in Neurobasal-based medium with different NGF concentrations ranging from 0 to 100 ng/mL and then treated with Sema3A at constant 10 ng/mL concentration. To evaluate interplay between NGF and Sema3A number of DRG axons, axon outgrowth distance and collapse rate were measured. We found that the increased NGF concentrations abolish Sema3A-induced inhibitory effect on axon outgrowth, while they have no effect on Sema3A-induced collapse rate.

Arginase Inhibition Suppresses Native Low-Density Lipoprotein-Stimulated Vascular Smooth Muscle Cell Proliferation by NADPH Oxidase Inactivation.

PubMed

Koo, Bon Hyeock; Yi, Bong Gu; Wang, Wi Kwang; Ko, In Young; Hoe, Kwang Lae; Kwon, Young Guen; Won, Moo Ho; Kim, Young Myeong; Lim, Hyun Kyo; Ryoo, Sungwoo

2018-05-01

Vascular smooth muscle cell (VSMC) proliferation induced by native low-density lipoprotein (nLDL) stimulation is dependent on superoxide production from activated NADPH oxidase. The present study aimed to investigate whether the novel arginase inhibitor limonin could suppress nLDL-induced VSMC proliferation and to examine related mechanisms. Isolated VSMCs from rat aortas were treated with nLDL, and cell proliferation was measured by WST-1 and BrdU assays. NADPH oxidase activation was evaluated by lucigenin-induced chemiluminescence, and phosphorylation of protein kinase C (PKC) βII and extracellular signal-regulated kinase (ERK) 1/2 was determined by western blot analysis. Mitochondrial reactive oxygen species (ROS) generation was assessed using MitoSOX-red, and intracellular L-arginine concentrations were determined by high-performance liquid chromatography (HPLC) in the presence or absence of limonin. Limonin inhibited arginase I and II activity in the uncompetitive mode, and prevented nLDL-induced VSMC proliferation in a p21Waf1/Cip1-dependent manner without affecting arginase protein levels. Limonin blocked PKCβII phosphorylation, but not ERK1/2 phosphorylation, and translocation of p47phox to the membrane was decreased, as was superoxide production in nLDL-stimulated VSMCs. Moreover, mitochondrial ROS generation was increased by nLDL stimulation and blocked by preincubation with limonin. Mitochondrial ROS production was responsible for the phosphorylation of PKCβII. HPLC analysis showed that arginase inhibition with limonin increases intracellular L-arginine concentrations, but decreases polyamine concentrations. L-Arginine treatment prevented PKCβII phosphorylation without affecting ERK1/2 phosphorylation. Increased L-arginine levels following limonin-dependent arginase inhibition prohibited NADPH oxidase activation in a PKCβII-dependent manner, and blocked nLDL-stimulated VSMC proliferation. © Copyright: Yonsei University College of Medicine 2018.

Arginase Inhibition Suppresses Native Low-Density Lipoprotein-Stimulated Vascular Smooth Muscle Cell Proliferation by NADPH Oxidase Inactivation

PubMed Central

Wang, Wi-Kwang; Ko, In-Young; Hoe, Kwang-Lae; Kwon, Young-Guen; Won, Moo-Ho; Kim, Young-Myeong

2018-01-01

Purpose Vascular smooth muscle cell (VSMC) proliferation induced by native low-density lipoprotein (nLDL) stimulation is dependent on superoxide production from activated NADPH oxidase. The present study aimed to investigate whether the novel arginase inhibitor limonin could suppress nLDL-induced VSMC proliferation and to examine related mechanisms. Materials and Methods Isolated VSMCs from rat aortas were treated with nLDL, and cell proliferation was measured by WST-1 and BrdU assays. NADPH oxidase activation was evaluated by lucigenin-induced chemiluminescence, and phosphorylation of protein kinase C (PKC) βII and extracellular signal-regulated kinase (ERK) 1/2 was determined by western blot analysis. Mitochondrial reactive oxygen species (ROS) generation was assessed using MitoSOX-red, and intracellular L-arginine concentrations were determined by high-performance liquid chromatography (HPLC) in the presence or absence of limonin. Results Limonin inhibited arginase I and II activity in the uncompetitive mode, and prevented nLDL-induced VSMC proliferation in a p21Waf1/Cip1-dependent manner without affecting arginase protein levels. Limonin blocked PKCβII phosphorylation, but not ERK1/2 phosphorylation, and translocation of p47phox to the membrane was decreased, as was superoxide production in nLDL-stimulated VSMCs. Moreover, mitochondrial ROS generation was increased by nLDL stimulation and blocked by preincubation with limonin. Mitochondrial ROS production was responsible for the phosphorylation of PKCβII. HPLC analysis showed that arginase inhibition with limonin increases intracellular L-arginine concentrations, but decreases polyamine concentrations. L-Arginine treatment prevented PKCβII phosphorylation without affecting ERK1/2 phosphorylation. Conclusion Increased L-arginine levels following limonin-dependent arginase inhibition prohibited NADPH oxidase activation in a PKCβII-dependent manner, and blocked nLDL-stimulated VSMC proliferation. PMID:29611398

Polarization Coupling in Ferroelectric Multilayers as a Function of Interface Charge Concentration

NASA Astrophysics Data System (ADS)

Okatan, Mahmut; Mantese, Joseph; Alpay, Pamir

2009-03-01

Intriguing properties of multilayered and graded ferroelectrics follow from the electrostatic and electromechanical interactions. The strength of the interlayer coupling depends on the concentration of interfacial defects with short-range local electrostatic fields. Defects may locally relax polarization differences and thus reduce the commensurate bound charge concentration at the interlayer interfaces. In this talk, we develop a theoretical analysis based on non-linear thermodynamics coupled with basic electrostatic relations to understand the role of charge compensation at the interlayer interfaces. The results show multilayered ferroelectrics with systematic variations in the composition may display a colossal dielectric response depending upon the interlayer electrostatic interactions. It is expected that other properties such as the pyroelectric and piezoelectric response will yield concomitant increases through the dielectric permittivity.

Suppression of Factor-Dependent Transcription Termination by Antiterminator RNA

PubMed Central

King, Rodney A.; Weisberg, Robert A.

2003-01-01

Nascent transcripts of the phage HK022 put sites modify the transcription elongation complex so that it terminates less efficiently at intrinsic transcription terminators and accelerates through pause sites. We show here that the modification also suppresses termination in vivo at two factor-dependent terminators, one that depends on the bacterial Rho protein and a second that depends on the HK022-encoded Nun protein. Suppression was efficient when the termination factors were present at physiological levels, but an increase in the intracellular concentration of Nun increased termination both in the presence and absence of put. put-mediated antitermination thus shows no apparent terminator specificity, suggesting that put inhibits a step that is common to termination at the different types of terminator. PMID:14645267

Effects of anhydrous AlCl3 dopant on the structural, optical and electrical properties of PVA-PVP polymer composite films

NASA Astrophysics Data System (ADS)

Shanmugam, G.; Krishnakumar, V.

2018-05-01

Polymer composite films based on PVA-PVP with AlCl3 as the dopant at different concentrations were prepared using solution casting technique. XRD patterns reveal the increase in amorphousity of the films with AlCl3 doping. Optical absorption studies exhibit that the values of optical absorption coefficient, direct and indirect optical band gaps are found to decrease with increase in AlCl3 concentration. It confirms the charge transfer in complexes between the polymer and the dopant. The dielectric studies show the increase in dielectric constant at low frequency with increasing AlCl3 concentration and temperature. The ac conductivity and ionic conductivity increase with the AlCl3 content and the maximum value at room temperature is found to be 6.89 × 10-4 and 8.05 × 10-5 S/cm for higher AlCl3 doped PVA-PVP film. The estimated ionic conductivity value is three or four orders of magnitude greater than those obtained in the certain representative polymer-salt complexes as reported earlier. Electrical modulus plots confirm the removal of electrode polarization and the low conductivity relaxation time with Al doping. The activation energy estimated from the temperature dependent dc conductivity plot is agreed well with the migration energy calculated from the temperature dependent electric modulus plot.

Senicapoc (ICA-17043): a potential therapy for the prevention and treatment of hemolysis-associated complications in sickle cell anemia.

PubMed

Ataga, Kenneth I; Stocker, Jonathan

2009-02-01

Sickle cell disease (SCD) is characterized by hemolytic as well as vaso-occlusive complications. The development of treatments for this inherited disease is based on an understanding of its pathophysiology. Polymerization of sickle hemoglobin is dependent on several independent factors, including the intracellular hemoglobin concentration. The hydration state (and intracellular hemoglobin concentration) of the sickle erythrocyte depends on the loss of solute and osmotically obliged water through specific pathways. Senicapoc (also known as ICA-17043) is a potent blocker of the Gardos channel, a calcium-activated potassium channel of intermediate conductance, in the red blood cell. Preclinical studies and studies in transgenic models of SCD show that inhibition of potassium efflux through the Gardos channel is associated with an increased hemoglobin level, decreased dense cells and decreased hemolysis. Senicapoc is well tolerated when administered to SCD patients and produces dose-dependent increases in hemoglobin and decreases in markers of hemolysis. Despite the lack of a reduction in the frequency of pain episodes, the increasing recognition that hemolysis contributes to the development of several SCD-related complications suggests that by decreasing hemolysis, senicapoc may yet prove to be beneficial in this disease.

Altering the concentration of silica tunes the functional properties of collagen-silica composite scaffolds to suit various clinical requirements.

PubMed

Perumal, Sathiamurthi; Ramadass, Satiesh Kumar; Gopinath, Arun; Madhan, Balaraman; Shanmugam, Ganesh; Rajadas, Jayakumar; Mandal, Asit Baran

2015-12-01

The success of a tissue engineering scaffold depends on a fine balance being achieved between the physicochemical and biological properties. This study attempts to understand the influence of silica concentration on the functional properties of collagen-silica (CS) composite scaffolds for soft tissue engineering applications. Increasing the ratio of silica to collagen (0.25, 0.5, 0.75, 1.0, 1.25, 1.5 and 2.0 w/w) gave a marked advantage in terms of improving the water uptake and compressive modulus of the CS scaffolds, while also enhancing the biological stability and the turnover time. With increase in silica concentration the water uptake and compressive modulus increased concurrently, whereas it was not so for surface porous architecture and biocompatibility which are crucial for cell adhesion and infiltration. Silica:collagen ratio of ≤1 exhibits favourable surface biocompatibility, and any further increase in silica concentration has a detrimental effect. Copyright © 2015 Elsevier Ltd. All rights reserved.

Free Energy Landscape of Cellulose as a Driving Factor in the Mobility of Adsorbed Water.

PubMed

Kulasinski, Karol

2017-06-06

The diffusion coefficient of water adsorbed in hydrophilic porous materials, such as noncrystalline cellulose, depends on water activity. Faster diffusion at higher water concentrations is observed in experimental and modeling studies. In this paper, two asymptotic water concentrations, near-vacuum and fully saturated, are investigated at the surface of crystalline cellulose with molecular dynamics simulations. An increasing water concentration leads to significant changes in the free energy landscape due to perturbation of local electrostatic potential. Smoothening of strong energy minima, corresponding to sorption sites, and formation of layered structure facilitates water transport in the vicinity of cellulose. The determined transition probabilities and hydrogen bond stability reflect the changes in the energy landscape. As a result of a concentration increase, the emerging basins of attraction and spreading out of those existing in the diluted state lead to an increase in water entropy. Thermal fluctuations of cellulose are demonstrated to rearrange the landscape in the diluted limit, increase adsorbed water entropy, and decrease the water-cellulose H-bond lifetime.

The Power Spectrum of Ionic Nanopore Currents: The Role of Ion Correlations.

PubMed

Zorkot, Mira; Golestanian, Ramin; Bonthuis, Douwe Jan

2016-04-13

We calculate the power spectrum of electric-field-driven ion transport through nanometer-scale membrane pores using both linearized mean-field theory and Langevin dynamics simulations. Remarkably, the linearized mean-field theory predicts a plateau in the power spectral density at low frequency ω, which is confirmed by the simulations at low ion concentration. At high ion concentration, however, the power spectral density follows a power law that is reminiscent of the 1/ω(α) dependence found experimentally at low frequency. On the basis of simulations with and without ion-ion interactions, we attribute the low-frequency power-law dependence to ion-ion correlations. We show that neither a static surface charge density, nor an increased pore length, nor an increased ion valency have a significant effect on the shape of the power spectral density at low frequency.

Expression of proliferative and inflammatory markers in a full-thickness human skin equivalent following exposure to the model sulfur mustard vesicant, 2-chloroethyl ethyl sulfide

PubMed Central

Black, Adrienne T.; Hayden, Patrick J.; Casillas, Robert P.; Heck, Diane E.; Gerecke, Donald R.; Sinko, Patrick J.; Laskin, Debra L.; Laskin, Jeffrey D.

2010-01-01

Sulfur mustard is a potent vesicant that induces inflammation, edema and blistering following dermal exposure. To assess molecular mechanisms mediating these responses, we analyzed the effects of the model sulfur mustard vesicant, 2-chloroethyl ethyl sulfide, on EpiDerm-FT™, a commercially available full-thickness human skin equivalent. CEES (100–1000 μM) caused a concentration-dependent increase in pyknotic nuclei and vacuolization in basal keratinocytes; at high concentrations (300–1000 μM), CEES also disrupted keratin filament architecture in the stratum corneum. This was associated with time-dependent increases in expression of proliferating cell nuclear antigen, a marker of cell proliferation, and poly(ADP-ribose) polymerase (PARP) and phosphorylated histone H2AX, markers of DNA damage. Concentration- and time-dependent increases in mRNA and protein expression of eicosanoid biosynthetic enzymes including COX-2, 5-lipoxygenase, microsomal PGE2 synthases, leukotriene (LT) A4 hydrolase and LTC4 synthase were observed in CEES-treated skin equivalents, as well as in antioxidant enzymes, glutathione S-transferases A1–2 (GSTA1–2), GSTA3 and GSTA4. These data demonstrate that CEES induces rapid cellular damage, cytotoxicity and inflammation in full-thickness skin equivalents. These effects are similar to human responses to vesicants in vivo and suggest that the full thickness skin equivalent is a useful in vitro model to characterize the biological effects of mustards and to develop potential therapeutics. PMID:20840853

Changes in the Chemical Composition of Plum Distillate During Maturation with Oak Chips under Different Conditions

PubMed Central

2017-01-01

Summary This study investigates the effect of ageing on the qualitative and quantitative composition of plum distillate in contact with oak wood chips. Maturation was performed with lightly toasted French oak (Quercus sessiflora and Quercus robur) chips or oak chips made from fragments of empty barrels that had been used for ageing cognac. The effects of oak chip dose, process temperature, ageing system (static or circulatory) and ultrasound treatment were assessed. Maturation of plum distillate samples with oak chips resulted in higher levels of extractable organics (including tannins) and colour changes, which were correlated with the type and dose of oak chips, and the conditions of maturation. The content of sugars such as glucose, xylose and arabinose also increased, depending on the conditions and type of oak chips. Degradation of lignin resulted in liberation of sinapaldehyde, syringaldehyde, coniferaldehyde and vanillin, with intensities depending on the applied parameters. In terms of volatiles, decreases in the concentration of higher alcohols and aliphatic aldehydes were observed in the majority of maturation experiments, while concentrations of furanic aldehydes increased depending on the type and dose of oak chips, as well as on the conditions of maturation. The quantities of esters such as ethyl acetate decreased in the majority of experimental variants, whereas concentrations of ethyl caproate, ethyl caprylate and ethyl caprate increased gradually. Some phenols and lactones were detected in all matured samples, with the lowest levels found in the samples aged with oak chips made from cognac barrels. PMID:29089848

Changes in the Chemical Composition of Plum Distillate During Maturation with Oak Chips under Different Conditions.

PubMed

Balcerek, Maria; Pielech-Przybylska, Katarzyna; Dziekońska-Kubczak, Urszula; Patelski, Piotr; Strąk, Ewelina

2017-09-01

This study investigates the effect of ageing on the qualitative and quantitative composition of plum distillate in contact with oak wood chips. Maturation was performed with lightly toasted French oak ( Quercus sessiflora and Quercus robur ) chips or oak chips made from fragments of empty barrels that had been used for ageing cognac. The effects of oak chip dose, process temperature, ageing system (static or circulatory) and ultrasound treatment were assessed. Maturation of plum distillate samples with oak chips resulted in higher levels of extractable organics (including tannins) and colour changes, which were correlated with the type and dose of oak chips, and the conditions of maturation. The content of sugars such as glucose, xylose and arabinose also increased, depending on the conditions and type of oak chips. Degradation of lignin resulted in liberation of sinapaldehyde, syringaldehyde, coniferaldehyde and vanillin, with intensities depending on the applied parameters. In terms of volatiles, decreases in the concentration of higher alcohols and aliphatic aldehydes were observed in the majority of maturation experiments, while concentrations of furanic aldehydes increased depending on the type and dose of oak chips, as well as on the conditions of maturation. The quantities of esters such as ethyl acetate decreased in the majority of experimental variants, whereas concentrations of ethyl caproate, ethyl caprylate and ethyl caprate increased gradually. Some phenols and lactones were detected in all matured samples, with the lowest levels found in the samples aged with oak chips made from cognac barrels.

Expression of proliferative and inflammatory markers in a full-thickness human skin equivalent following exposure to the model sulfur mustard vesicant, 2-chloroethyl ethyl sulfide.

PubMed

Black, Adrienne T; Hayden, Patrick J; Casillas, Robert P; Heck, Diane E; Gerecke, Donald R; Sinko, Patrick J; Laskin, Debra L; Laskin, Jeffrey D

2010-12-01

Sulfur mustard is a potent vesicant that induces inflammation, edema and blistering following dermal exposure. To assess molecular mechanisms mediating these responses, we analyzed the effects of the model sulfur mustard vesicant, 2-chloroethyl ethyl sulfide, on EpiDerm-FT™, a commercially available full-thickness human skin equivalent. CEES (100-1000 μM) caused a concentration-dependent increase in pyknotic nuclei and vacuolization in basal keratinocytes; at high concentrations (300-1000 μM), CEES also disrupted keratin filament architecture in the stratum corneum. This was associated with time-dependent increases in expression of proliferating cell nuclear antigen, a marker of cell proliferation, and poly(ADP-ribose) polymerase (PARP) and phosphorylated histone H2AX, markers of DNA damage. Concentration- and time-dependent increases in mRNA and protein expression of eicosanoid biosynthetic enzymes including COX-2, 5-lipoxygenase, microsomal PGE₂ synthases, leukotriene (LT) A₄ hydrolase and LTC₄ synthase were observed in CEES-treated skin equivalents, as well as in antioxidant enzymes, glutathione S-transferases A1-2 (GSTA1-2), GSTA3 and GSTA4. These data demonstrate that CEES induces rapid cellular damage, cytotoxicity and inflammation in full-thickness skin equivalents. These effects are similar to human responses to vesicants in vivo and suggest that the full thickness skin equivalent is a useful in vitro model to characterize the biological effects of mustards and to develop potential therapeutics. Copyright © 2010 Elsevier Inc. All rights reserved.

Temperature transition of human hemoglobin at body temperature: effects of calcium.

PubMed Central

Kelemen, C; Chien, S; Artmann, G M

2001-01-01

We studied the effects of calcium ion concentration on the temperature dependence of rheological behavior of human red blood cells (RBCs) and concentrated hemoglobin solutions. Our previous study (G. M. Artmann, C. Kelemen, D. Porst, G. Büldt, and S. Chien, 1998, Biophys. J., 75:3179-3183) showed a critical temperature (Tc) of 36.4 +/- 0.3 degrees C at which the RBCs underwent a transition from non-passage to passage through 1.3 microm micropipettes in response to an aspiration pressure of -2.3 kPa. An increase in intracellular Ca2+ concentration by using the ionophore A23187 reduced the passability of intact RBCs through small micropipettes above T(c); the micropipette diameter needed for >90% passage increased to 1.7 microm. Viscometry of concentrated hemoglobin solutions (45 and 50 g/dl) showed a sudden viscosity transition at 36 +/- 1 degrees C (Tc(eta)) at all calcium concentrations investigated. Below Tc(eta), the viscosity value of the concentrated hemoglobin solution at 1.8 mM Ca(2+) was higher than that at other concentrations (0.2 microM, 9 mM, and 18 mM). Above Tc(eta), the viscosity was almost Ca2+ independent. At 1.8 mM Ca2+ and 36 +/- 1 degrees C, the activation energy calculated from the viscometry data showed a strong dependence on the hemoglobin concentration. We propose that the transition of rheological behavior is attributable to a high-to-low viscosity transition mediated by a partial release of the hemoglobin-bound water. PMID:11371439

Plasma clot formation and clot lysis to compare effects of different anticoagulation treatments on hemostasis in patients with atrial fibrillation.

PubMed

Königsbrügge, Oliver; Weigel, Günter; Quehenberger, Peter; Pabinger, Ingrid; Ay, Cihan

2018-02-07

The effect of direct oral anticoagulants (DOACs) on turbidimetric measurements of plasma clot formation and susceptibility to fibrinolysis may facilitate a comparison between different classes of anticoagulants in plasma samples. We obtained 424 citrate plasma samples from 226 atrial fibrillation patients on anticoagulation and 24 samples without anticoagulation serving as controls. As comparators, we measured the international normalized ratio (INR) for phenprocoumon samples (N = 166), anti-Xa for low molecular weight heparin (LMWH) samples (N = 42), and DOAC levels with mass spectrometry (dabigatran N = 40, rivaroxaban N = 110, apixaban N = 42). Plasma clot formation and lysis were recorded continuously on a photometer after addition of an activation mix (tissue factor 2 pmol/l and tissue plasminogen activator 333 ng/ml). We used linear regression and ANCOVA for correlation analysis. Clot formation lag phase was prolonged in the presence of anticoagulants in a concentration-dependent manner for DOACs (dabigatran Spearman r = 0.74; rivaroxaban r = 0.78; apixaban r = 0.72, all p < 0.0001), INR dependent for phenprocoumon (r = 0.59, p < 0.0001), anti-Xa level dependent in LMWH samples (r = 0.90, p < 0.0001). Maximum rate of clot formation and peak clot turbidity were reduced in the presence of anticoagulants, but correlated only moderately with the comparator measures of anticoagulation. The clot lysis time was inversely correlated with DOAC concentrations in the presence of recombinant thrombomodulin. A direct ex vivo comparison between the effects of different classes of anticoagulants is possible with turbidimetric measurement of plasma clot formation and lysis. Anticoagulation inhibited clot formation in a plasma concentration manner for DOACs, INR dependent for phenprocoumon, and anti-Xa dependent for LMWH. Susceptibility to fibrinolysis increased with increasing DOAC concentrations.

Effect of COPD treatments on MRP1-mediated transport in bronchial epithelial cells

PubMed Central

van der Deen, Margaretha; Homan, Sandra; Timmer-Bosscha, Hetty; Scheper, Rik J; Timens, Wim; Postma, Dirkje S; de Vries, Elisabeth G

2008-01-01

Background Smoking is the principle risk factor for development of chronic obstructive pulmonary disease (COPD). Multidrug resistance-associated protein 1 (MRP1) is known to protect against toxic compounds and oxidative stress, and might play a role in protection against smoke-induced disease progression. We questioned whether MRP1-mediated transport is influenced by pulmonary drugs that are commonly prescribed in COPD. Methods The immortalized human bronchial epithelial cell line 16HBE14o− was used to analyze direct in vitro effects of budesonide, formoterol, ipratropium bromide and N-acetylcysteine (NAC) on MRP1-mediated transport. Carboxyfluorescein (CF) was used as a model MRP1 substrate and was measured with functional flow cytometry. Results Formoterol had a minor effect, whereas budesonide concentration-dependently decreased CF transport by MRP1. Remarkably, addition of formoterol to the highest concentration of budesonide increased CF transport. Ipratropium bromide inhibited CF transport at low concentrations and tended to increase CF transport at higher levels. NAC increased CF transport by MRP1 in a concentration-dependent manner. Conclusions Our data suggest that, besides their positive effects on respiratory symptoms, budesonide, formoterol, ipratropium bromide, and NAC modulate MRP1 activity in bronchial epithelial cells. Further studies are required to assess whether stimulation of MRP1 activity is beneficial for long-term treatment of COPD. PMID:18990976

Metabolomic Responses of Arabidopsis Suspension Cells to Bicarbonate under Light and Dark Conditions

PubMed Central

Misra, Biswapriya B.; Yin, Zepeng; Geng, Sisi; de Armas, Evaldo; Chen, Sixue

2016-01-01

Global CO2 level presently recorded at 400 ppm is expected to reach 550 ppm in 2050, an increment likely to impact plant growth and productivity. Using targeted LC-MS and GC-MS platforms we quantified 229 and 29 metabolites, respectively in a time-course study to reveal short-term responses to different concentrations (1, 3, and 10 mM) of bicarbonate (HCO3−) under light and dark conditions. Results indicate that HCO3− treatment responsive metabolomic changes depend on the HCO3− concentration, time of treatment, and light/dark. Interestingly, 3 mM HCO3− concentration treatment induced more significantly changed metabolites than either lower or higher concentrations used. Flavonoid biosynthesis and glutathione metabolism were common to both light and dark-mediated responses in addition to showing concentration-dependent changes. Our metabolomics results provide insights into short-term plant cellular responses to elevated HCO3− concentrations as a result of ambient increases in CO2 under light and dark. PMID:27762345

Physical dependence on nitrous oxide in mice: resemblance to alcohol but not to opiate withdrawal.

PubMed

Milne, B; Cervenko, F W; Jhamandas, K H

1981-01-01

Mice of two strains, Crl:CD-1(1CR)Br and C57BL6, were exposed to nitrous oxide at concentrations of 50, 65 and 80 per cent for 34 or 68 hours. Cessation of nitrous oxide resulted in characteristic convulsions similar to those seen in alcohol withdrawal in all mice. These peaked in severity within 2-3 minutes after removal from nitrous oxide and declined over 6 hours. The severity and duration of these convulsions were related to the nitrous oxide concentration and duration of exposure. Naloxone or naltrexone produced no significant increase in severity of convulsions. The narcotic antagonists did not precipitate acute weight loss or characteristic jumping behaviour seen in animals dependent on opiates. These results demonstrate that chronic exposure to nitrous oxide results in development of physical dependence which resembles alcohol and not opiate dependence. Analgesia and physical dependence produced by nitrous oxide appear to be mediated through separate mechanisms.

Role of monovalent cations in fluid secretion from the exocrine rabbit pancreas.

PubMed

Kuijpers, G A; Van Nooy, I G; De Pont, J J

1989-08-21

The role of Na+ in fluid secretion by the isolated rabbit pancreas was investigated. The fluid secretion rate is reduced upon replacement of Na+ in the bathing medium by Li+, K+ or choline. The inhibition depends on the nature of the substituting cation, and is largest with choline. Upon replacement, the substituent cation appears in the secreted fluid, and the Na+ concentration in the secreted fluid is decreased in a mirror-like fashion. When Na+ is replaced by Li+ or choline, the secretory Na+ concentration is decreased, although less than in the bathing medium, and the K+ concentration is increased. When Na+ is replaced by K+, the Na+ and the K+ concentration in the secreted fluid are approximately equal to their bathing medium concentrations. In the Li+ and choline medium, stimulation of the pancreas by carbachol or CCK-8 increases the fluid secretion rate. In addition, it increases the Li+ or choline concentration, and decreases the Na+ and K+ concentrations in the secreted fluid. In normal and K+ medium, stimulation causes only a slight increase in fluid secretion rate, with no change in the secretory Na+ concentration. In normal medium, stimulation leads to a decrease in the secretory K+ concentration. The effects of replacing Na+ appear to be the result of a direct inhibition of the active HCO3- transport underlying secretion, and an indirect inhibition related to the permeability of the pancreas for the various cations. The stimulants are likely to act by increasing the permeability of the tight junctions.

Fish mercury increase in Lago Manso, a new hydroelectric reservoir in tropical Brazil.

PubMed

Hylander, Lars D; Gröhn, Janina; Tropp, Magdalena; Vikström, Anna; Wolpher, Henriette; de Castro E Silva, Edinaldo; Meili, Markus; Oliveira, Lázaro J

2006-10-01

It has been frequently demonstrated that mercury (Hg) concentrations in fish rise in newly constructed hydroelectric reservoirs in the Northern Hemisphere. In the present work, we studied whether similar effects take place also in a tropical upland reservoir during impoundment and discuss possible causes and implications. Total Hg concentrations in fish and several soil and water parameters were determined before and after flooding at Rio Manso hydroelectric power plant in western Brazil. The Hg concentrations in soil and sediment were within the background levels in the region (22-35 ng g(-1) dry weight). There was a strong positive correlation between Hg and carbon and sulphur in sediment. Predatory fish had total Hg concentrations ranging between 70 and 210 ng g(-1) f.w. 7 years before flooding and between 72 and 755 ng g(-1) f.w. during flooding, but increased to between 216 and 938 ng g(-1) f.w. in the piscivorous and carnivorous species Pseudoplatystoma fasciatum, cachara, and Salminus brasiliensis, dourado, 3 years after flooding. At the same time, concentrations of organic carbon in the water increased and oxygen concentrations decreased, indicating increased decomposition and anoxia as contributing to the increased Hg concentrations in fish. The present fish Hg concentrations in commonly consumed piscivorous species are a threat to the health of the population dependent on fishing in the dam and downstream river for sustenance. Mercury exposure can be reduced by following fish consumption recommendations until fish Hg concentrations decrease to a safe level.

Possible role for increased C4b-binding-protein level in acquired protein S deficiency in type I diabetes.

PubMed

Ceriello, A; Giugliano, D; Quatraro, A; Marchi, E; Barbanti, M; Lefebvre, P

1990-04-01

In this study, total protein S (PS) immunological levels, free-PS and C4b-binding-protein (C4bBP) concentrations, and PS functional activity were investigated in insulin-dependent (type I) diabetic patients and compared with nondiabetic subjects. Mean total PS antigen concentration was not different between diabetic patients and nondiabetic subjects, whereas free-PS levels and PS functional activity were significantly reduced in diabetic patients. C4bBP was increased in diabetic patients and correlated with HbA1 levels. This study shows that type I diabetic patients have depressed free PS and PS activity despite the presence of normal total PS concentration and suggests that this phenomenon is probably linked to the increase of circulating C4bBP.

Impact of Vitamin B12 and Nitrate Availability on the Concentration of Particulate Dimethylsulfoniopropionate in Phytoplankton

NASA Astrophysics Data System (ADS)

Zavala, J.; Lee, P. A.; Schanke, N. L.; Pound, H.; Penta, W. B.; Shore, S. K.

2016-02-01

The production of particulate dimethylsulfoniopropionate (DMSPp) was examined in natural phytoplankton communities from the South Atlantic Bight near Savannah, Georgia, during an expedition in June 2015. Vitamin B12 and nitrate were added to seawater samples from a coastal and an oceanic site, both of which contained low-biomass, cyanobacteria-dominated communities. Under nitrate-limited conditions, irrespective of changes in B12 levels, DMSPp concentrations increased. DMSPp concentrations of these mixed phytoplankton communities did not appear to be limited by the availability of B12. In a laboratory experiment, DMSPp concentrations in the diatom Phaeodactylum tricornutum were measured after the removal of vitamin B12 and nitrate from a synthetic seawater culture media. DMSPp concentrations increased under nitrate-limited conditions, irrespective of changes in B12 levels, and are argued to be the result of increased biosynthesis. DMSPp concentrations in P. tricornutum were unaffected by B12 limitation. It is hypothesized that P. tricornutum is using the B12-independent methionine synthase MetE to synthesize DMSPp rather than the B12-dependent methionine synthase MetH.

Comparison of intracellular drug retention, DNA damage and cytotoxicity of derivatives of doxorubicin and daunorubicin in a human colon adenocarcinoma cell line (LoVo).

PubMed

Belvedere, G; Suarato, A; Geroni, C; Giuliani, F C; D'Incalci, M

1989-11-01

Formation of DNA single strand breaks (SSB) was assayed by alkaline elution in LoVo cells treated with doxorubicin, daunorubicin and six derivatives of these drugs modified either in the chromophore or the sugar. Seven compounds showed a biphasic relationship (initial increase and then a decrease) for the formation of DNA-SSB over the concentration range 0.05-10 micrograms/ml. At a drug concentration in the range causing an increase of DNA damage very fast repair of DNA-SSB was observed for 4'-deoxydoxorubicin and 4-demethoxydaunorubicin; the kinetics of DNA-SSB investigated after drug removal at a drug concentration reducing DNA-SSB showed a time dependent increase of DNA damage for both drugs although with different patterns. 4'-Deoxydoxorubicin reduced the effect of radiations on the rate of elution of DNA in a way resembling the formation of DNA interstrand cross links (ISC) at concentrations at which DNA-SSB were reduced. DNA-ISC were not produced by chemical reactions occurring during sample processing for alkaline elution and this derivative was not metabolized by LoVo cells. The IC50 of the anthracyclines were on a several log range, though for most of the derivatives the cytotoxicity curve showed a plateau at growth inhibition of about 15-30% at increasing intracellular drug levels. A relationship between DNA damage and cytotoxicity was observed only in a very small range of DNA-SSB. It is likely that the different effects of these anthracyclines on the formation of DNA-SSB depend on a qualitatively different interaction between drug-DNA and topoisomerase II when the drug concentration is raised.

Oxidative stress and antioxidant responses to increasing concentrations of trivalent chromium in the Andean crop species Chenopodium quinoa Willd.

PubMed

Scoccianti, Valeria; Bucchini, Anahi E; Iacobucci, Marta; Ruiz, Karina B; Biondi, Stefania

2016-11-01

Quinoa (Chenopodium quinoa Willd), an ancient Andean seed crop, exhibits exceptional nutritional properties and resistance to abiotic stress. The species' tolerance to heavy metals has, however, not yet been investigated nor its ability to take up and translocate chromium (Cr). This study aimed to investigate the metabolic adjustments occurring upon exposure of quinoa to several concentrations (0.01-5mM) of CrCl3. Young hydroponically grown plants were used to evaluate Cr uptake, growth, oxidative stress, and other biochemical parameters three and/or seven days after treatment. Leaves accumulated the lowest amounts of Cr, while roots and stems accumulated the most at low and at high metal concentrations, respectively. Fresh weight and photosynthetic pigments were reduced only by the higher Cr(III) doses. Substantially increased lipid peroxidation, hydrogen peroxide, and proline levels were observed only with 5mM Cr(III). Except for a significant decrease at day 7 with 5mM Cr(III), total polyphenols and flavonoids maintained control levels in Cr(III)-treated plants, whereas antioxidant activity increased in a dose-dependent manner. Maximum polyamine accumulation was observed in 1mM CrCl3-treated plants. Even though α- and γ-tocopherols also showed enhanced levels only with the 1mM concentration, tyrosine aminotransferase (TAT, EC 2.6.1.5) activity increased under Cr(III) treatment in a dose- and time-dependent manner. Taken together, results suggest that polyamines, tocopherols, and TAT activity could contribute to tolerance to 1mM Cr(III), but not to the highest concentration that, instead, generated oxidative stress. Copyright © 2016 Elsevier Inc. All rights reserved.

Tuning the electrocaloric effect by varying Sr concentration in ferroelectric Ba1 -xSrxTiO3

NASA Astrophysics Data System (ADS)

Lisenkov, S.; Ponomareva, I.

2018-05-01

The electrocaloric effect is investigated systematically in Ba1 -xSrxTiO3 ferroelectrics using a semiclassical direct computational approach. The data are reported for the technologically important range of Sr concentrations of 0.0-0.6, electric fields up to 1000 kV/cm, and temperatures ranging from 5 to 600 K. A detailed comparison of computational data with experimental data from the literature reveals semiquantitative agreement and suggests the origin of discrepancies. The electrocaloric change in temperature Δ T shows strong dependence on Sr concentration which offers a way to tune electrocaloric response. In particular, the maximum electrocaloric Δ T is found to decrease with the increase in Sr concentration, whereas the location of the maximum shifts towards lower temperatures following the Curie point of the ferroelectric. Surprisingly, the width of the peak in the dependence of Δ T on the initial temperature is independent of the Sr concentration but shows a strong dependence on the applied electric field. Computational data are used to propose a compositionally graded ferroelectric Ba0.70Sr0.30TiO3/Ba0.55Sr0.45TiO3/Ba0.50Sr0.50TiO3/Ba0.45Sr0.55TiO3 whose Δ T shows almost no temperature dependence in the technologically important range of temperatures and electric fields. Such a desirable feature could potentially lead to the enhancement of relative cooling power.

Concentration dependent requirement for local protein synthesis in motor neuron subtype specific response to axon guidance cues

PubMed Central

Nedelec, Stephane; Peljto, Mirza; Shi, Peng; Amoroso, Mackenzie W.; Kam, Lance C.; Wichterle, Hynek

2012-01-01

Formation of functional motor circuits relies on the ability of distinct spinal motor neuron subtypes to project their axons with high precision to appropriate muscle targets. While guidance cues contributing to motor axon pathfinding have been identified, the intracellular pathways underlying subtype specific responses to these cues remain poorly understood. In particular, it remains controversial whether responses to axon guidance cues depend on axonal protein synthesis. Using a growth cone collapse assay, we demonstrate that mouse embryonic stem cell (ESC) derived spinal motor neurons (ES-MNs) respond to ephrin-A5, Sema3f and Sema3a in a concentration dependent manner. At low doses, ES-MNs exhibit segmental or subtype specific responses, while this selectivity is lost at higher concentrations. Response to high doses of semaphorins and to all doses of ephrin-A5 is protein synthesis independent. In contrast, using microfluidic devices and stripe assays, we show that growth cone collapse and guidance at low concentrations of semaphorins relies on local protein synthesis in the axonal compartment. Similar bimodal response to low and high concentrations of guidance cues is observed in human ES-MNs, pointing to a general mechanism by which neurons increase their repertoire of responses to the limited set of guidance cues involved in neural circuit formation. PMID:22279234

GABAB receptor-mediated frequency-dependent and circadian changes in synaptic plasticity modulate retinal input to the suprachiasmatic nucleus

PubMed Central

Moldavan, Mykhaylo G; Allen, Charles N

2013-01-01

Light is the most important environmental signal that entrains the circadian clock located in the hypothalamic suprachiasmatic nucleus (SCN). The retinohypothalamic tract (RHT) was stimulated to simulate the light intensity-dependent discharges of intrinsically photosensitive retinal ganglion cells projecting axons to the hypothalamus. EPSCs were evoked by paired-pulse stimulation or by application of stimulus trains, and recorded from SCN neurons in rat brain slices. Initial release probability (Pr) and synaptic plasticity changes depended on the strength of GABAB receptor (GABABR)-mediated presynaptic inhibition and could be different at the same GABABR agonist concentration. Facilitation caused by frequency-dependent relief of GABABR-mediated inhibition was observed when the initial Pr was decreased to less than 15% of control during strong activation of presynaptic GABAB receptors by (±)baclofen (10 μm), GABA (≥2 mm) or by GABA uptake inhibitor nipecotic acid (≥5 mm). In contrast, short-term synaptic depression appeared during baclofen (10 μm) application when initial Pr was greater than 30% of control. Block of 4-aminopyridine-sensitive K+ currents increased the amplitude and time constant of decay of evoked EPSCs (eEPSCs), and decreased the GABABR-mediated presynaptic inhibition. The GABAB receptor antagonist CGP55845 (3 μm) increased the eEPSCs amplitude 30% throughout the light−dark cycle. During light and dark phases the RHT inputs to 55% and 33% of recorded neurons, respectively, were under GABAB inhibitory control indicating that the tonic inhibition induced by local changes of endogenous GABA concentration contributes to the circadian variation of RHT transmitter release. We conclude that GABABR-mediated presynaptic inhibition decreased with increasing frequency and broadening of presynaptic action potentials, and depended on the sensitivity of RHT terminals to GABABR agonists, and diurnal changes of the extracellular GABA concentration around RHT axon terminals in the SCN. PMID:23401614

Interplay Between Cytosolic Free Zn2+ and Mitochondrion Morphological Changes in Rat Ventricular Cardiomyocytes.

PubMed

Billur, Deniz; Tuncay, Erkan; Okatan, Esma Nur; Olgar, Yusuf; Durak, Aysegul Toy; Degirmenci, Sinan; Can, Belgin; Turan, Belma

2016-11-01

The Zn 2+ in cardiomyocytes is buffered by structures near T-tubulus and/or sarcoplasmic/endoplasmic reticulum (S(E)R) while playing roles as either an antioxidant or a toxic agent, depending on the concentration. Therefore, we aimed first to examine a direct effect of ZnPO 4 (extracellular exposure) or Zn 2+ pyrithione (ZnPT) (intracellular exposure) application on the structure of the mitochondrion in ventricular cardiomyocytes by using histological investigations. The light microscopy data demonstrated that Zn 2+ exposure induced marked increases on cellular surface area, an indication of hypertrophy, in a concentration-dependent manner. Furthermore, a whole-cell patch-clamp measurement of cell capacitance also supported the hypertrophy in the cells. We observed marked increases in mitochondrial matrix/cristae area and matrix volume together with increased lysosome numbers in ZnPO 4 - or ZnPT-incubated cells by using transmission electron microscopy, again in a concentration-dependent manner. Furthermore, we observed notable clustering and vacuolated mitochondrion, markedly disrupted and damaged myofibrils, and electron-dense small granules in Zn 2+ -exposed cells together with some implications of fission-fusion defects in the mitochondria. Moreover, we observed marked depolarization in mitochondrial membrane potential during 1-μM ZnPT minute applications by using confocal microscopy. We also showed that 1-μM ZnPT incubation induced significant increases in the phosphorylation levels of GSK3β (Ser21 and Ser9), Akt (Ser473), and NFκB (Ser276 and Thr254) together with increased expression levels in ER stress proteins such as GRP78 and calregulin. Furthermore, a new key player at ER-mitochondria sites, promyelocytic leukemia protein (PML) level, was markedly increased in ZnPT-incubated cells. As a summary, our present data suggest that increased cytosolic free Zn 2+ can induce marked alterations in mitochondrion morphology as well as depolarization in mitochondrion membrane potential and changes in some cytosolic signaling proteins as well as a defect in ER-mitochondria cross talk.

Countercurrent distribution of biological cells

NASA Technical Reports Server (NTRS)

1982-01-01

It is known that the addition of phosphate buffer to two polymer aqueous phase systems has a strong effect on the partition behavior of cells and other particles in such mixtures. The addition of sodium phosphate to aqueous poly(ethylene glycol) dextran phase systems causes a concentration-dependent shift in binodial on the phase diagram, progressively lowering the critical conditions for phase separation as the phosphate concentration is increased. Sodium chloride produces no significant shift in the critical point relative to the salt-free case. Accurate determinations of the phase diagram require measurements of the density of the phases; data is presented which allows this parameter to be calculated from polarimetric measurements of the dextran concentrations of both phases. Increasing polymer concentrations in the phase systems produce increasing preference of the phosphate for the dextran-rich bottom phase. Equilibrium dialysis experiments showed that poly(ethylene glycol) effectively rejected phosphate, and to a lesser extent chloride, but that dextran had little effect on the distribution of either salt. Increasing ionic strength via addition of 0.15 M NaCl to phase systems containing 0.01 M phosphate produces an increased concentration of phosphate ions in the bottom dextran-rich phase, the expected effect in this type of Donnan distribution.

Mineral water administration may increase kidney elimination of urea, creatinine and folic acid in a concentration-dependent fashion.

PubMed

Calomino, Francesco; Di Paolo, Nicola; Nicolai, Giulia; Miglio, Antonio

2010-05-01

In a previous experimental study we showed that the administration of a large water load in a short time increases the urinary flow and the transport capacity in the excretory tract of the rabbit ureter. In human subjects drinking a water load of 25 ml/kg(BW) in 30 minutes, diuresis, creatinine and urea clearance increase more than in those drinking the same load in 24 hours. The aim of the present study was to investigate possible correlations between percent reduction and baseline values of serum urea, creatinine, folic acid, and magnesium in humans. 20 volunteers were divided in two groups. Subjects in group 1 received a water load of 25 ml/kg(BW) in 24 hours followed by the same load in 30 minutes. Subjects in group 2 received the same water load but in inverse order. Before and after each water administration, the following variables were measured and compared: diuresis, serum urea, creatinine, folic acid and magnesium concentration, and urea and creatinine clearance. Serum urea and folic acid concentration decreased up to 40% after administration of the water load in 24 hours. Serum creatinine concentration decreased up to 20% after administration of the water load in 30 minutes. The concentration drop of these metabolites increased with increasing baseline metabolite concentrations.

Organic anion exudation by ectomycorrhizal fungi and Pinus sylvestris in response to nutrient deficiencies.

PubMed

van Schöll, Laura; Hoffland, Ellis; van Breemen, Nico

2006-01-01

Low molecular weight organic anions (LMWOA) can enhance weathering of mineral grains. We tested the hypothesis that ectomycorrhizal (EcM) fungi and tree seedlings increase their exudation of LMWOA when supply of magnesium, potassium and phosphorus is low to enhance the mobilization of Mg, K and P from mineral grains. Ectomycorrhizal fungi and Pinus sylvestris seedlings were cultured in symbiosis and in isolation on glass beads with nutrient solution or with sand as a rooting medium, with a complete nutrient supply or with Mg, K, P or N in low supply. Concentrations of all dicarboxylic LMWOA in the rooting medium were measured. Nonmycorrhizal seedlings released predominantly malonate. Colonization with Hebeloma longicaudum decreased the amount of organic anions exuded, whereas Paxillus involutus and Piloderma croceum increased the concentration of oxalate but not the total amount of LMWOA. Phosphorus deficiency increased the concentration of LMWOA by nonmycorrhizal and EcM seedlings. Magnesium deficiency increased the concentration of oxalate by nonmycorrhizal and EcM seedlings, but not the concentration of total LMWOA. Paxillus involutus grown in pure culture responded differently to low nutrient supply compared with symbiotic growth. Ectomycorrhizal fungi did not increase the total concentration of LMWOA compared with nonmycorrhizal seedlings but, depending on the fungal species, they affected the type of LMWOA found.

Response of single bacterial cells to stress gives rise to complex history dependence at the population level

PubMed Central

Mathis, Roland; Ackermann, Martin

2016-01-01

Most bacteria live in ever-changing environments where periods of stress are common. One fundamental question is whether individual bacterial cells have an increased tolerance to stress if they recently have been exposed to lower levels of the same stressor. To address this question, we worked with the bacterium Caulobacter crescentus and asked whether exposure to a moderate concentration of sodium chloride would affect survival during later exposure to a higher concentration. We found that the effects measured at the population level depended in a surprising and complex way on the time interval between the two exposure events: The effect of the first exposure on survival of the second exposure was positive for some time intervals but negative for others. We hypothesized that the complex pattern of history dependence at the population level was a consequence of the responses of individual cells to sodium chloride that we observed: (i) exposure to moderate concentrations of sodium chloride caused delays in cell division and led to cell-cycle synchronization, and (ii) whether a bacterium would survive subsequent exposure to higher concentrations was dependent on the cell-cycle state. Using computational modeling, we demonstrated that indeed the combination of these two effects could explain the complex patterns of history dependence observed at the population level. Our insight into how the behavior of single cells scales up to processes at the population level provides a perspective on how organisms operate in dynamic environments with fluctuating stress exposure. PMID:26960998

[Callose accumulation during treatment of tomato (Lycopersicon esculentum L.) cells with biotic elicitors].

PubMed

Emel'ianov, V I; Kravchuk, Zh N; Poliakovskiĭ, S A; Dmitriev, A P

2008-01-01

Time-course of induced accumulation of callose in tomato cells has been studied. Localization of callose in L. esculenthum cells was investigated by fluorescent microscopy technique, and the optimal time for its determination was found. Callose accumulation in tomato cells treated with different biotic elicitors was determined. Nonlinear dependence between callose accumulation and concentration of chitin oligomers (with 3-5 N-acetylglucosamine fragments) was established. Increasing of callose accumulation in tomato cells was proportional to the increase of concentration ofchitin dimer and chitosan in the culture medium.

Relationship between cobalamin-dependent metabolites and both serum albumin and alpha1 -proteinase inhibitor concentrations in hypocobalaminemic dogs of 7 different breeds.

PubMed

Grützner, Niels; Suchodolski, Jan S; Steiner, Jörg M

2014-12-01

Increased serum concentrations of homocysteine (HCY) and methylmalonic acid (MMA), the 2 main cobalamin-dependent metabolites, as well as decreased serum albumin and canine alpha1 -proteinase inhibitor (cα1 -PI) concentrations have previously been described in hypocobalaminemic dogs with gastrointestinal disease. However, no studies have been conducted to evaluate potential relationships between these serum biomarkers. The aim of this study was to evaluate the relationship between HCY and MMA, 2 cobalamin-dependent metabolites, and both serum albumin and cα1 -PI concentrations in hypocobalaminemic dogs. Serum samples from 285 dogs including 7 different breeds (Beagle, Boxer, Cocker Spaniel, German Shepherd, Labrador Retriever, Chinese Shar-Pei, and Yorkshire Terrier) with hypocobalaminemia were used. Serum HCY, MMA, albumin, and cα1 -PI concentrations were determined. There was a significant correlation between serum HCY and albumin concentrations, as well as serum HCY and cα1 -PI concentrations (ρ = 0.62 and ρ = 0.37, respectively; P < .0001). No correlations were observed between serum MMA and albumin concentrations, or cα1 -PI concentrations (ρ = 0.01 and ρ = 0.08, respectively; P > .05). In addition, significant breed-specific correlations were observed between serum MMA and albumin concentrations in German Shepherds, and serum HCY and MMA concentrations in Chinese Shar-Peis with hypocobalaminemia. This study shows a correlation between serum albumin and cα1 -PI and HCY concentrations, but not with serum MMA concentration in dogs with hypocobalaminemia. In addition, significant breed-specific correlations were observed between serum MMA and albumin concentrations in German Shepherds, as well as serum HCY and MMA concentrations in Chinese Shar-Peis, emphasizing the unique metabolic interactions in those dog breeds affected by hypocobalaminemia. © 2014 American Society for Veterinary Clinical Pathology.

Nitric oxide signaling pathway regulates potassium chloride cotransporter-1 mRNA expression in vascular smooth muscle cells.

PubMed

Di Fulvio, M; Lauf, P K; Adragna, N C

2001-11-30

Rat vascular smooth muscle cells (VSMCs) express at least two mRNAs for K-Cl cotransporters (KCC): KCC1 and KCC3. cGMP-dependent protein kinase I regulates KCC3 mRNA expression in these cells. Here, we show evidence implicating the nitric oxide (NO)/cGMP signaling pathway in the expression of KCC1 mRNA, considered to be the major cell volume regulator. VSMCs, expressing soluble guanylyl cyclase (sGC) and PKG-I isoforms showed a time- and concentration-dependent increase in KCC1 mRNA levels after treatment with sodium nitroprusside as demonstrated by semiquantitative RT-PCR. sGC-dependent regulation of KCC1 mRNA expression was confirmed using YC-1, a NO-independent sGC stimulator. The sGC inhibitor LY83583 blocked the effects of sodium nitroprusside and YC-1. Moreover, 8-Br-cGMP increased KCC1 mRNA expression in a concentration- and time-dependent fashion. The 8-Br-cGMP effect was partially blocked by KT5823 but not by actinomycin D. However, actinomycin D and cycloheximide increased basal KCC1 mRNA in an additive manner, suggesting different mechanisms of action for both drugs. These findings suggest that in VSMCs, the NO/cGMP-signaling pathway participates in KCC1 mRNA regulation at the post-transcriptional level.

CdSe/ZnS Quantum Dots trigger DNA repair and antioxidant enzyme systems in Medicago sativa cells in suspension culture

PubMed Central

2013-01-01

Background Nanoparticles appear to be promising devices for application in the agriculture and food industries, but information regarding the response of plants to contact with nano-devices is scarce. Toxic effects may be imposed depending on the type and concentration of nanoparticle as well as time of exposure. A number of mechanisms may underlie the ability of nanoparticles to cause genotoxicity, besides the activation of ROS scavenging mechanisms. In a previous study, we showed that plant cells accumulate 3-Mercaptopropanoic acid-CdSe/ZnS quantum dots (MPA-CdSe/ZnS QD) in their cytosol and nucleus and increased production of ROS in a dose dependent manner when exposed to QD and that a concentration of 10 nM should be cyto-compatible. Results When Medicago sativa cells were exposed to 10, 50 and 100 nM MPA-CdSe/ZnS QD a correspondent increase in the activity of Superoxide dismutase, Catalase and Glutathione reductase was registered. Different versions of the COMET assay were used to assess the genotoxicity of MPA-CdSe/ZnS QD. The number of DNA single and double strand breaks increased with increasing concentrations of MPA-CdSe/ZnS QD. At the highest concentrations, tested purine bases were more oxidized than the pyrimidine ones. The transcription of the DNA repair enzymes Formamidopyrimidine DNA glycosylase, Tyrosyl-DNA phosphodiesterase I and DNA Topoisomerase I was up-regulated in the presence of increasing concentrations of MPA-CdSe/ZnS QD. Conclusions Concentrations as low as 10 nM MPA-CdSe/ZnS Quantum Dots are cytotoxic and genotoxic to plant cells, although not lethal. This sets a limit for the concentrations to be used when practical applications using nanodevices of this type on plants are being considered. This work describes for the first time the genotoxic effect of Quantum Dots in plant cells and demonstrates that both the DNA repair genes (Tdp1β, Top1β and Fpg) and the ROS scavenging mechanisms are activated when MPA-CdSe/ZnS QD contact M. sativa cells. PMID:24359290

Poly(styrene-co-butadiene) random copolymer thin films and nanostructures on a mica surface: morphology and contact angles of nanodroplets.

PubMed

McClements, Jake; Buffone, Cosimo; Shaver, Michael P; Sefiane, Khellil; Koutsos, Vasileios

2017-09-20

The self-assembly of poly(styrene-co-butadiene) random copolymers on mica surfaces was studied by varying solution concentrations and polymer molecular weights. Toluene solutions of the poly(styrene-co-butadiene) samples were spin coated onto a mica surface and the resulting polymer morphology was investigated by atomic force microscopy. At higher concentrations, thin films formed with varying thicknesses; some dewetting was observed which depended on the molecular weight. Total dewetting did not occur despite the polymer's low glass transition temperature. Instead, partial dewetting was observed suggesting that the polymer was in a metastable equilibrium state. At lower concentrations, spherical cap shaped nanodroplets formed with varying sizes from single polymer chains to aggregates containing millions of chains. As the molecular weight was increased, fewer aggregates were observed on the surface, albeit with larger sizes resulting from increased solution viscosities and more chain entanglements at higher molecular weights. The contact angles of the nanodroplets were shown to be size dependent. A minimum contact angle occurs for droplets with radii of 100-250 nm at each molecular weight. Droplets smaller than 100 nm showed a sharp increase in contact angle; attributed to an increase in the elastic modulus of the droplets, in addition, to a positive line tension value. Droplets larger than 250 nm also showed an increased contact angle due to surface heterogeneities which cannot be avoided for larger droplets. This increase in contact angle plateaus as the droplet size reaches the macroscopic scale.

Resveratrol Exerts Dosage and Duration Dependent Effect on Human Mesenchymal Stem Cell Development

PubMed Central

Peltz, Lindsay; Gomez, Jessica; Marquez, Maribel; Alencastro, Frances; Atashpanjeh, Negar; Quang, Tara; Bach, Thuy; Zhao, Yuanxiang

2012-01-01

Studies in the past have illuminated the potential benefit of resveratrol as an anticancer (pro-apoptosis) and life-extending (pro-survival) compound. However, these two different effects were observed at different concentration ranges. Studies of resveratrol in a wide range of concentrations on the same cell type are lacking, which is necessary to comprehend its diverse and sometimes contradictory cellular effects. In this study, we examined the effects of resveratrol on cell self-renewal and differentiation of human mesenchymal stem cells (hMSCs), a type of adult stem cells that reside in a number of tissues, at concentrations ranging from 0.1 to 10 µM after both short- and long-term exposure. Our results reveal that at 0.1 µM, resveratrol promotes cell self-renewal by inhibiting cellular senescence, whereas at 5 µM or above, resveratrol inhibits cell self-renewal by increasing senescence rate, cell doubling time and S-phase cell cycle arrest. At 1 µM, its effect on cell self-renewal is minimal but after long-term exposure it exerts an inhibitory effect, accompanied with increased senescence rate. At all concentrations, resveratrol promotes osteogenic differentiation in a dosage dependent manner, which is offset by its inhibitory effect on cell self-renewal at high concentrations. On the contrary, resveratrol suppresses adipogenic differentiation during short-term exposure but promotes this process after long-term exposure. Our study implicates that resveratrol is the most beneficial to stem cell development at 0.1 µM and caution should be taken in applying resveratrol as an anticancer therapeutic agent or nutraceutical supplement due to its dosage dependent effect on hMSCs. PMID:22615926

Experimental Investigations of Boron, Lithium, and Halogens During High-Temperature Water-Rock Interaction: Insights into the Yellowstone Hydrothermal System

NASA Astrophysics Data System (ADS)

Cullen, J. T.; Hurwitz, S.; Thordsen, J. J.; Barnes, J.

2017-12-01

B, Li, and halogens (Cl, F, Br) are used extensively in studies of thermal waters to infer fluid equilibrium conditions with the host reservoir lithology, and quantify the possible fraction of a magmatic component in thermal waters. Apart from fluorine, the limited number of minerals that incorporate these elements support the notion that they preferentially partition into an aqueous fluid during high temperature water-rock interaction. Although limited experimental work is largely consistent with these observations, a rigorous experimental investigation is required to quantify the mobility of these elements under conditions emulating a silicic hydrothermal system. Here we present the results from water-rhyolite interaction batch experiments conducted over a range of temperatures between 150 °C and 350 °C and 250 bar. Powdered obsidian from Yellowstone was reacted with MiliQ water and sampled intermittently throughout the duration of the 90 day experiment. The experimental data show that at temperatures ≤ 200 °C, B, Cl, Br, and Li are not readily leached from the rhyolite, whereas aqueous F- concentration increases by a factor of 3.5 when the temperature was increased from 150 °C to 200 °C. Between 200 °C and 250 °C, B concentration increased by more than an order of magnitude and Cl- concentration increased by a factor of 5. F- concentration increased by a factor of 3. Between 250 °C and 300 °C the opposite trend was observed, in which F- concentration decreased by 60%, Br- concentration increased by a factor of 5, and Cl- and B concentrations increased by more than an order of magnitude. The progressive decrease of aqueous F- at T ≥ 300 °C is likely controlled by precipitation into a fluorine bearing secondary mineral(s). Our experimental results demonstrate that leaching of B, Li, Cl, F, and Br from rhyolite is highly temperature-dependent between 150 °C and 350 °C. These results can provide context to infer the sources of solutes discharged at thermal springs and the subsurface water-rhyolite equilibrium temperatures in the Yellowstone hydrothermal system. Work to characterize the alteration mineralogy and the temperature-dependent stable Cl, Li, and B isotope fractionation is currently ongoing. Keywords: Yellowstone, hydrothermal, halogens, experiments, water-rock interaction

Experimental Investigations of Boron, Lithium, and Halogens During High-Temperature Water-Rock Interaction: Insights into the Yellowstone Hydrothermal System

NASA Astrophysics Data System (ADS)

Cullen, J. T.; Hurwitz, S.; Thordsen, J. J.; Barnes, J.

2016-12-01

B, Li, and halogens (Cl, F, Br) are used extensively in studies of thermal waters to infer fluid equilibrium conditions with the host reservoir lithology, and quantify the possible fraction of a magmatic component in thermal waters. Apart from fluorine, the limited number of minerals that incorporate these elements support the notion that they preferentially partition into an aqueous fluid during high temperature water-rock interaction. Although limited experimental work is largely consistent with these observations, a rigorous experimental investigation is required to quantify the mobility of these elements under conditions emulating a silicic hydrothermal system. Here we present the results from water-rhyolite interaction batch experiments conducted over a range of temperatures between 150 °C and 350 °C and 250 bar. Powdered obsidian from Yellowstone was reacted with MiliQ water and sampled intermittently throughout the duration of the 90 day experiment. The experimental data show that at temperatures ≤ 200 °C, B, Cl, Br, and Li are not readily leached from the rhyolite, whereas aqueous F- concentration increases by a factor of 3.5 when the temperature was increased from 150 °C to 200 °C. Between 200 °C and 250 °C, B concentration increased by more than an order of magnitude and Cl- concentration increased by a factor of 5. F- concentration increased by a factor of 3. Between 250 °C and 300 °C the opposite trend was observed, in which F- concentration decreased by 60%, Br- concentration increased by a factor of 5, and Cl- and B concentrations increased by more than an order of magnitude. The progressive decrease of aqueous F- at T ≥ 300 °C is likely controlled by precipitation into a fluorine bearing secondary mineral(s). Our experimental results demonstrate that leaching of B, Li, Cl, F, and Br from rhyolite is highly temperature-dependent between 150 °C and 350 °C. These results can provide context to infer the sources of solutes discharged at thermal springs and the subsurface water-rhyolite equilibrium temperatures in the Yellowstone hydrothermal system. Work to characterize the alteration mineralogy and the temperature-dependent stable Cl, Li, and B isotope fractionation is currently ongoing. Keywords: Yellowstone, hydrothermal, halogens, experiments, water-rock interaction

Calorimetric and relaxation properties of xylitol-water mixtures

NASA Astrophysics Data System (ADS)

Elamin, Khalid; Sjöström, Johan; Jansson, Helén; Swenson, Jan

2012-03-01

We present the first broadband dielectric spectroscopy (BDS) and differential scanning calorimetry study of supercooled xylitol-water mixtures in the whole concentration range and in wide frequency (10-2-106 Hz) and temperature (120-365 K) ranges. The calorimetric glass transition, Tg, decreases from 247 K for pure xylitol to about 181 K at a water concentration of approximately 37 wt. %. At water concentrations in the range 29-35 wt. % a plentiful calorimetric behaviour is observed. In addition to the glass transition, almost simultaneous crystallization and melting events occurring around 230-240 K. At higher water concentrations ice is formed during cooling and the glass transition temperature increases to a steady value of about 200 K for all higher water concentrations. This Tg corresponds to an unfrozen xylitol-water solution containing 20 wt. % water. In addition to the true glass transition we also observed a glass transition-like feature at 220 K for all the ice containing samples. However, this feature is more likely due to ice dissolution [A. Inaba and O. Andersson, Thermochim. Acta, 461, 44 (2007)]. In the case of the BDS measurements the presence of water clearly has an effect on both the cooperative α-relaxation and the secondary β-relaxation. The α-relaxation shows a non-Arrhenius temperature dependence and becomes faster with increasing concentration of water. The fragility of the solutions, determined by the temperature dependence of the α-relaxation close to the dynamic glass transition, decreases with increasing water content up to about 26 wt. % water, where ice starts to form. This decrease in fragility with increasing water content is most likely caused by the increasing density of hydrogen bonds, forming a network-like structure in the deeply supercooled regime. The intensity of the secondary β-relaxation of xylitol decreases noticeably already at a water content of 2 wt. %, and at a water content above 5 wt. % it has been replaced by a considerably stronger water (w) relaxation at about the same frequency. However, the similarities in time scale and activation energy between the w-relaxation and the β-relaxation of xylitol at water contents below 13 wt. % suggest that the w-relaxation is governed, in some way, by the β-relaxation of xylitol, since clusters of water molecules are rare at these water concentrations. At higher water concentrations the intensity and relaxation rate of the w-relaxation increase rapidly with increasing water content (up to the concentration where ice starts to form), most likely due to a rapid increase of small water clusters where an increasing number of water molecules interacting with other water molecules.

Climate dependency of tree growth suppressed by acid deposition effects on soils in Northwest Russia

USGS Publications Warehouse

Lawrence, G.B.; Lapenis, A.G.; Berggren, D.; Aparin, B.F.; Smith, K.T.; Shortle, W.C.; Bailey, S.W.; Varlyguin, D.L.; Babikov, B.

2005-01-01

Increased tree growth in temperate and boreal forests has been proposed as a direct consequence of a warming climate. Acid deposition effects on nutrient availability may influence the climate dependency of tree growth, however. This study presents an analysis of archived soil samples that has enabled changes in soil chemistry to be tracked with patterns of tree growth through the 20th century. Soil samples collected in 1926, 1964, and 2001, near St. Petersburg, Russia, showed that acid deposition was likely to have decreased root-available concentrations of Ca (an essential element) and increased root-available concentrations of Al (an inhibitor of Ca uptake). These soil changes coincided with decreased diameter growth and a suppression of climate-tree growth relationships in Norway spruce. Expected increases in tree growth from climate warming may be limited by decreased soil fertility in regions of northern and eastern Europe, and eastern North America, where Ca availability has been reduced by acidic deposition. ?? 2005 American Chemical Society.

Effect of Silver Doping on Transport Properties of Bi2Se3: AgxBi2Se3 and Bi2-xAgxSe3

NASA Astrophysics Data System (ADS)

Zhang, Min; Wei, Zhan-Tao

2018-05-01

Ag-doped Bi2Se3 with the formula AgxBi2Se3 and Bi2-xAgxSe3 were prepared and their electrical and magnetic transport properties have been investigated to study the influence of silver doping on transport properties of Bi2Se3 with different Ag-doped method. All samples exhibited metallic resistivity and the resistivity increased with increasing Ag concentration. The lattice parameter c of Ag-substituted and Ag-intercalated samples displays a contrary change as the Ag concentration increased. For the Ag-intercalated samples, both the resistance upturn were observed in the curves of temperature dependent of resistivity and temperature dependent of magnetoresistance, respectively, indicating that the enhanced surface effect was obtained in those samples. Monotonously, field-induced MR peaks around 200 K were also observed in those samples. Similar behaviors were not observed in the Ag-substituted samples.

Myosin concentration underlies cell size–dependent scalability of actomyosin ring constriction

PubMed Central

Wright, Graham D.; Leong, Fong Yew; Chiam, Keng-Hwee; Chen, Yinxiao; Jedd, Gregory; Balasubramanian, Mohan K.

2011-01-01

In eukaryotes, cytokinesis is accomplished by an actomyosin-based contractile ring. Although in Caenorhabditis elegans embryos larger cells divide at a faster rate than smaller cells, it remains unknown whether a similar mode of scalability operates in other cells. We investigated cytokinesis in the filamentous fungus Neurospora crassa, which exhibits a wide range of hyphal circumferences. We found that N. crassa cells divide using an actomyosin ring and larger rings constricted faster than smaller rings. However, unlike in C. elegans, the total amount of myosin remained constant throughout constriction, and there was a size-dependent increase in the starting concentration of myosin in the ring. We predict that the increased number of ring-associated myosin motors in larger rings leads to the increased constriction rate. Accordingly, reduction or inhibition of ring-associated myosin slows down the rate of constriction. Because the mechanical characteristics of contractile rings are conserved, we predict that these findings will be relevant to actomyosin ring constriction in other cell types. PMID:22123864

Long-term effects of guar gum in subjects with non-insulin-dependent diabetes mellitus.

PubMed

Groop, P H; Aro, A; Stenman, S; Groop, L

1993-10-01

The effects of 15 g guar gum/d on glycemic control, lipids, and insulin secretion were studied in 15 (8 male, 7 female) diet-treated subjects with non-insulin-dependent diabetes mellitus for 48 wk. Mean age (+/- SD) was 60 +/- 2 y (range 45-70 y), body mass index (in kg/m2) 28.6 +/- 0.9 (range 21.6 +/- 39.2), and duration of diabetes 6 +/- 1 y (range 2-14 y). Guar gum was preceded and followed by 8-wk placebo periods. Guar gum improved long-term glycemic control, postprandial glucose tolerance and lipid concentrations. The C-peptide response to a test meal increased by time during guar gum treatment, whereas the insulin response remained unchanged. This indicates that insulin secretion is enhanced by guar gum as reflected by increased C-peptide. A decreased molar ratio of insulin to C-peptide suggests that guar gum may increase hepatic insulin extraction. In conclusion, guar gum has favorable long-term effects on glycemic control and lipid concentrations.

Climate dependency of tree growth suppressed by acid deposition effects on soils in northwest Russia.

PubMed

Lawrence, Gregory B; Lapenis, Andrei G; Berggren, Dan; Aparin, Boris F; Smith, Kevin T; Shortle, Walter C; Bailey, Scott W; Varlyguin, Dmitry L; Babikov, Boris

2005-04-01

Increased tree growth in temperate and boreal forests has been proposed as a direct consequence of a warming climate. Acid deposition effects on nutrient availability may influence the climate dependency of tree growth, however. This study presents an analysis of archived soil samples that has enabled changes in soil chemistry to be tracked with patterns of tree growth through the 20th century. Soil samples collected in 1926, 1964, and 2001, near St. Petersburg, Russia, showed that acid deposition was likely to have decreased root-available concentrations of Ca (an essential element) and increased root-available concentrations of Al (an inhibitor of Ca uptake). These soil changes coincided with decreased diameter growth and a suppression of climate-tree growth relationships in Norway spruce. Expected increases in tree growth from climate warming may be limited by decreased soil fertility in regions of northern and eastern Europe, and eastern North America, where Ca availability has been reduced by acidic deposition.

Assessment of nickel titanium and beta titanium corrosion resistance behavior in fluoride and chloride environments.

PubMed

Kassab, Elisa J; Gomes, José Ponciano

2013-09-01

To assess the influence of fluoride concentration on the corrosion behavior of nickel titanium (NiTi) superelastic wire and to compare the corrosion resistance of NiTi with that of beta titanium alloy in physiological solution with and without addition of fluoride. NiTi corrosion resistance was investigated through electrochemical impedance spectroscopy and anodic polarization in sodium chloride (NaCl 0.15 M) with and without addition of 0.02 M sodium fluoride (NaF), and the results were compared with those associated with beta titanium. The influence of fluoride concentration on NiTi corrosion behavior was assessed in NaCl (0.15 M) with and without 0.02, 0.04, 0.05, 0.07, and 0.12 M NaF solution. Galvanic corrosion between NiTi and beta titanium were investigated. All samples were characterized by scanning electron microscopy. Polarization resistance decreased when NaF concentration was increased, and, depending on NaF concentration, NiTi can suffer localized or generalized corrosion. In NaCl solution with 0.02 M NaF, NiTi suffer localized corrosion, while beta titanium alloys remained passive. Current values near zero were observed by galvanic coupling of NiTi and beta titanium. There is a decrease in NiTi corrosion resistance in the presence of fluoride. The corrosion behavior of NiTi alloy depends on fluoride concentration. When 0.02 and 0.04 M of NaF were added to the NaCl solution, NiTi presented localized corrosion. When NaF concentration increased to 0.05, 0.07, and 0.12 M, the alloy presented general corrosion. NiTi corrosion resistance behavior is lower than that of beta titanium. Galvanic coupling of these alloys does not increase corrosion rates.

Hormetic effects of noncoplanar PCB exposed to human lung fibroblast cells (HELF) and possible role of oxidative stress.

PubMed

Hashmi, Muhammad Zaffar; Khan, Kiran Yasmin; Hu, Jinxing; Naveedullah; Su, Xiaomei; Abbas, Ghulam; Yu, Chunna; Shen, Chaofeng

2015-12-01

Hormesis, a biphasic dose-response phenomenon, which is characterized by stimulation of an end point at a low-dose and inhibition at a high-dose. In the present study we used human lungs fibroblast (HELF) cells as a test model to evaluate the role of oxidative stress (OS) in hormetic effects of non coplanar PCB 101. Results from 3-(4,5-dime-thylthiazol-2-yl)-2,5-diphenyltetrazo-lium bromide (MTT) assay indicated that PCB101 at lower concentrations (10(-5) to 10(-1) μg mL(-1) ) stimulated HELF cell proliferation and inhibited at high concentrations (1, 5, 10, and 20 μg mL(-1) ) in a dose- and time-dependent manner. Reactive oxygen species (ROS), malondialdehyde (MDA) and superoxide dismutase (SOD) (except 48 h) showed a significant increase at higher concentrations of PCB 101 than those at the lower concentrations with the passage of time. Antioxidant enzymes such as glutathione peroxidase (GSH-Px) exhibited decreasing trends in dose and time dependent manner. Lipid peroxidation assay resulted in a significant increase (P < 0.05) of MDA level in PCB 101-treated HELF cells compared with controls, suggesting that OS plays a key role in PCB 101-induced toxicity. Comet assay indicated a significant increase in genotoxicity at higher concentrations of PCB 101 exposure compared to lower concentrations. Overall, we found that HELF cell proliferation was higher at low ROS level and vice versa, which revealed activation of cell signaling-mediated hormetic mechanisms. The results suggested that PCB 101 has hormetic effects to HELF cells and these were associated with oxidative stress. © 2014 Wiley Periodicals, Inc.

Molecular Binding Contributes to Concentration Dependent Acrolein Deposition in Rat Upper Airways: CFD and Molecular Dynamics Analyses

PubMed Central

Hu, Qin; Si, Xiuhua April

2018-01-01

Existing in vivo experiments show significantly decreased acrolein uptake in rats with increasing inhaled acrolein concentrations. Considering that high-polarity chemicals are prone to bond with each other, it is hypothesized that molecular binding between acrolein and water will contribute to the experimentally observed deposition decrease by decreasing the effective diffusivity. The objective of this study is to quantify the probability of molecular binding for acrolein, as well as its effects on acrolein deposition, using multiscale simulations. An image-based rat airway geometry was used to predict the transport and deposition of acrolein using the chemical species model. The low Reynolds number turbulence model was used to simulate the airflows. Molecular dynamic (MD) simulations were used to study the molecular binding of acrolein in different media and at different acrolein concentrations. MD results show that significant molecular binding can happen between acrolein and water molecules in human and rat airways. With 72 acrolein embedded in 800 water molecules, about 48% of acrolein compounds contain one hydrogen bond and 10% contain two hydrogen bonds, which agreed favorably with previous MD results. The percentage of hydrogen-bonded acrolein compounds is higher at higher acrolein concentrations or in a medium with higher polarity. Computational dosimetry results show that the size increase caused by the molecular binding reduces the effective diffusivity of acrolein and lowers the chemical deposition onto the airway surfaces. This result is consistent with the experimentally observed deposition decrease at higher concentrations. However, this size increase can only explain part of the concentration-dependent variation of the acrolein uptake and acts as a concurrent mechanism with the uptake-limiting tissue ration rate. Intermolecular interactions and associated variation in diffusivity should be considered in future dosimetry modeling of high-polarity chemicals such as acrolein. PMID:29584651

Changes in free amino acid concentrations and associated gene expression profiles in the abdominal muscle of kuruma shrimp (Marsupenaeus japonicus) acclimated at different salinities.

PubMed

Koyama, Hiroki; Mizusawa, Nanami; Hoashi, Masataka; Tan, Engkong; Yasumoto, Ko; Jimbo, Mitsuru; Ikeda, Daisuke; Yokoyama, Takehiko; Asakawa, Shuichi; Piyapattanakorn, Sanit; Watabe, Shugo

2018-06-05

Shrimps inhabiting coastal waters can survive in a wide range of salinity. However, the molecular mechanisms involved in their acclimation to different environmental salinities have remained largely unknown. In the present study, we acclimated kuruma shrimp ( Marsupenaeus japonicus ) at 1.7%, 3.4% and 4.0% salinities. After acclimating for 6, 12, 24 and 72 h, we determined free amino acid concentrations in their abdominal muscle, and performed RNA sequencing analysis on this muscle. The concentrations of free amino acids were clearly altered depending on salinity after 24 h of acclimation. Glutamine and alanine concentrations were markedly increased following the increase of salinity. In association with such changes, many genes related to amino acid metabolism changed their expression levels. In particular, the increase of the expression level of the gene encoding glutamate-ammonia ligase, which functions in glutamine metabolism, appeared to be associated with the increased glutamine concentration at high salinity. Furthermore, the increased alanine concentration at high salinity was likely associated with the decrease in the expression levels of the the gene encoding alanine-glyoxylate transaminase. Thus, there is a possibility that changes in the concentration of free amino acids for osmoregulation in kuruma shrimp are regulated by changes in the expression levels of genes related to amino acid metabolism. © 2018. Published by The Company of Biologists Ltd.

Cross-sectional and prospective relation of cannabis potency, dosing and smoking behaviour with cannabis dependence: an ecological study.

PubMed

van der Pol, Peggy; Liebregts, Nienke; Brunt, Tibor; van Amsterdam, Jan; de Graaf, Ron; Korf, Dirk J; van den Brink, Wim; van Laar, Margriet

2014-07-01

Increased delta-9-tetrahydrocannabinol (THC) concentrations in cannabis may lead to higher THC exposure, cannabis dependence and treatment need, but users may also adapt the actual intake of THC through reduced inhalation of THC containing smoke (titration). We investigated whether consumers of stronger cannabis use less cannabis per joint or inhale less smoke than those using less potent cannabis and whether these factors predict cannabis dependence severity. Heavy cannabis users (n = 98) brought their own cannabis, rolled a joint and smoked it ad libitum in a naturalistic setting. We analysed the content of the joint, its association with smoking behaviour and the cross-sectional and prospective (1.5-year follow-up) relations between smoking behaviour and cannabis dependence severity (total number of DSM-IV dependence symptoms). THC concentration in cannabis (range 1.10-24.70%) was correlated positively with cannabis dose per joint (b = 0.008, P = 0.01), but the resulting THC concentration per joint (range 0.24-15.72%) was associated negatively with inhalation volume (b = -0.05, P = 0.03). Smoking behaviour measures (number of puffs, inhaled volume, reduction of puff volume and puff duration while smoking) predicted follow-up dependence severity, independently of baseline dependence severity and monthly THC dose (number of joints × cannabis dose × cannabis THC concentration). Monthly THC dose only predicted follow-up dependence severity when unadjusted for baseline severity. Cannabis users titrate their delta-9-tetrahydrocannabinol intake by inhaling lower volumes of smoke when smoking strong joints, but this does not fully compensate for the higher cannabis doses per joint when using strong cannabis. Thus, users of more potent cannabis are generally exposed to more delta-9-tetrahydrocannabinol. Smoking behaviour appears to be a stronger predictor for cannabis dependence severity than monthly delta-9-tetrahydrocannabinol dose. © 2014 Society for the Study of Addiction.

Bi-phasic regulation of glycogen content in astrocytes via Cav-1/PTEN/PI3K/AKT/GSK-3β pathway by fluoxetine.

PubMed

Bai, Qiufang; Song, Dan; Gu, Li; Verkhratsky, Alexei; Peng, Liang

2017-04-01

Here, we present the data indicating that chronic treatment with fluoxetine regulates Cav-1/PTEN/PI3K/AKT/GSK-3β signalling pathway and glycogen content in primary cultures of astrocytes with bi-phasic concentration dependence. At lower concentrations, fluoxetine downregulates gene expression of Cav-1, decreases membrane content of PTEN, increases activity of PI3K/AKT, and elevates GSK-3β phosphorylation thus suppressing its activity. At higher concentrations, fluoxetine acts in an inverse fashion. As expected, fluoxetine at lower concentrations increased while at higher concentrations decreased glycogen content in astrocytes. Our findings indicate that bi-phasic regulation of glycogen content via Cav-1/PTEN/PI3K/AKT/GSK-3β pathway by fluoxetine may be responsible for both therapeutic and side effects of the drug.

Distribution of lead in selected organs and its effect on reproduction parameters of pheasants (Phasianus colchicus) after an experimental per oral administration.

PubMed

Gasparik, Jozef; Venglarcik, Jozef; Slamecka, Jaroslav; Kropil, Rudolf; Smehyl, Peter; Kopecky, Jan

2012-01-01

Lead poisoning has been reported in almost every country on earth. In this study the effect of experimental lead pellet intake (2-6 pellets per week [groups B2, B4, B6] and ad libitum [BAD] accessibility for 10 weeks) on its distribution in liver, kidney, pectoral muscle, ovary, eggs and the effect of selected reproductive parameters (egg weight, fertilization, hatchability) was analyzed in breeding pheasants. Lead pellets were force fed to the digestive tract (struma, ingluvies) and the ingestion was controlled. Concentration of lead was detected using the atomic absorption spectrophotometry. Analysis of the lead concentration in liver showed a significantly higher concentration in all group after the lead pellets intake. The increase of the lead concentration was dose-dependent and the concentration detected in group BAD was similar as in group B2. Very similar tendencies were detected for the lead concentration in kidney. The accumulation of lead in pectoral muscle was lower, in comparison with liver and kidney. Compared to lead concentration detected in ovary of the control group a significant increase was detected in all experimental groups, reaching the maximum in the group B6. Similar significant increase of lead concentration was detected in eggs. The average weight of eggs was 32.01 ± 2.71 g in the control group and lower in all experimental groups, but this decrease was significant only in the group B6. The fertilization rate was the highest in the control group and a dose-dependent decrease was detected with the lowest value in the group B6. For egg hatching ratio a significant decrease was detected in groups B4 and B6. Results of this study clearly describe accumulation of lead in the body and a its negative effect on the reproductive parameters. In the ad libitum experimental group the most similar results were found as in group B2, suggesting a rate of "natural" lead pellet intake.

The relation of seismic activity and radon concentration

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

Kulali, Feride, E-mail: feridekulali@gmail.com, E-mail: iskender@fef.sdu.edu.tr; Akkurt, İskender, E-mail: feridekulali@gmail.com, E-mail: iskender@fef.sdu.edu.tr; Vogiannis, Efstratios, E-mail: svog@env.aegean.gr

Radon, which is the largest source of natural ionizing radiation, reaches to surface as gas or dissolved form in the ground water. Emanation of radon can has a profile is disposed to increasing or decreasing depending on the effects of meteorological events or crust movements. In this work, the radon concentration in soil gas, which is transported from soil to AlphaGUARD, is continuously measured in Mytilene (Greece). A graph of radon concentration is prepared for comparison with simultaneous earthquake data. As a consequence of comparison, we determined that the radon concentration indicates anomalies before the earthquakes.

Measurement of formaldehyde concentrations in a subatmospheric steam-formaldehyde autoclave.

PubMed Central

Marcos, D; Wiseman, D

1979-01-01

A method has been developed for measuring formaldehyde concentrations in a subatmospheric steam-formaldehyde autoclave. Data obtained using this method indicate that the concentration of formaldehyde in the chamber atmosphere is not homogeneous and that it decreases rapidly with time. The penetration of formaldehyde vapour into narrow tubes has also been investigated and was shown to be dependent on the length-to-bore ratio of the tubes. The formaldehyde concentration within the tubes could be increased by using a lower vacuum in the air removal stage at the beginning of the cycle. PMID:572833

Time-dependent oral absorption models

NASA Technical Reports Server (NTRS)

Higaki, K.; Yamashita, S.; Amidon, G. L.

2001-01-01

The plasma concentration-time profiles following oral administration of drugs are often irregular and cannot be interpreted easily with conventional models based on first- or zero-order absorption kinetics and lag time. Six new models were developed using a time-dependent absorption rate coefficient, ka(t), wherein the time dependency was varied to account for the dynamic processes such as changes in fluid absorption or secretion, in absorption surface area, and in motility with time, in the gastrointestinal tract. In the present study, the plasma concentration profiles of propranolol obtained in human subjects following oral dosing were analyzed using the newly derived models based on mass balance and compared with the conventional models. Nonlinear regression analysis indicated that the conventional compartment model including lag time (CLAG model) could not predict the rapid initial increase in plasma concentration after dosing and the predicted Cmax values were much lower than that observed. On the other hand, all models with the time-dependent absorption rate coefficient, ka(t), were superior to the CLAG model in predicting plasma concentration profiles. Based on Akaike's Information Criterion (AIC), the fluid absorption model without lag time (FA model) exhibited the best overall fit to the data. The two-phase model including lag time, TPLAG model was also found to be a good model judging from the values of sum of squares. This model also described the irregular profiles of plasma concentration with time and frequently predicted Cmax values satisfactorily. A comparison of the absorption rate profiles also suggested that the TPLAG model is better at prediction of irregular absorption kinetics than the FA model. In conclusion, the incorporation of a time-dependent absorption rate coefficient ka(t) allows the prediction of nonlinear absorption characteristics in a more reliable manner.

Bepridil differentially inhibits two delayed rectifier K+ currents, IKr and IKs, in guinea-pig ventricular myocytes

PubMed Central

Wang, Jin-Cheng; Kiyosue, Tatsuto; Kiriyama, Kuninori; Arita, Makoto

1999-01-01

We investigated the effects of bepridil on the two components of the delayed rectifier K+ current, i.e., the rapidly activating (IKr) and the slowly activating (IKs) currents using tight-seal whole-cell patch-clamp techniques in guinea-pig ventricular myocytes, under blockade of L-type Ca2+ current with nitrendipine (5 μM) or D600 (1 μM).Bepridil decreased IKs under blockade of IKr with E4031 (5 μM), in a concentration-dependent manner. The concentration-dependent inhibition of IKs by bepridil was fitted by a curve, assuming one-to-one interactions between the channel and the drug molecule. The concentration of half-maximal inhibition (IC50) was found to be 6.2 μM.The effect of bepridil on IKr was assessed using an envelope-of-tails test. In the control condition, a ratio of the tail current to the time-dependent current measured during depolarization was large (>1) at shorter pulses (<200 ms), and it decreased to a steady state value of ∼0.4 with increases in the pulse duration. Bepridil at a concentration of 2 μM did not decrease this ratio at shorter pulses.In a short-pulse (duration=50 ms) experiment that largely activates IKr, the drug was found to block IKr in a cooperative manner (Hill coefficient=3.03) and the IC50 was 13.2 μM.These results suggest that bepridil at a clinical therapeutic concentration (∼2 μM) selectively blocks IKs but does not inhibit IKr. This may relate to the characteristic frequency-dependent effects of bepridil on the action potential duration (APD), e.g., the non-reverse use-dependent prolongation of APD. PMID:10588929

Effects of lead on Na+, K+-ATPase and hemolymph ion concentrations in the freshwater mussel Elliptio complanata

USGS Publications Warehouse

Mosher, Shad; Cope, W. Gregory; Weber, Frank X.; Shea, Damian; Kwak, Thomas J.

2012-01-01

Freshwater mussels are an imperiled fauna exposed to a variety of environmental toxicants such as lead (Pb) and studies are urgently needed to assess their health and condition to guide conservation efforts. A 28-day laboratory toxicity test with Pb and adult Eastern elliptio mussels (Elliptio complanata) was conducted to determine uptake kinetics and to assess the toxicological effects of Pb exposure. Test mussels were collected from a relatively uncontaminated reference site and exposed to a water-only control and five concentrations of Pb (as lead nitrate) ranging from 1 to 245 mu g/L in a static renewal test with a water hardness of 42 mg/L. Endpoints included tissue Pb concentrations, hemolymph Pb and ion (Na+, K+, Cl-, Ca2+) concentrations, and Na+, K+-ATPase enzyme activity in gill tissue. Mussels accumulated Pb rapidly, with tissue concentrations increasing at an exposure-dependent rate for the first 2 weeks, but with no significant increase from 2 to 4 weeks. Mussel tissue Pb concentrations ranged from 0.34 to 898 mu g/g dry weight, were strongly related to Pb in test water at every time interval (7, 14, 21, and 28 days), and did not significantly increase after day 14. Hemolymph Pb concentration was variable, dependent on exposure concentration, and showed no appreciable change with time beyond day 7, except for mussels in the greatest exposure concentration (245 mu g/L), which showed a significant reduction in Pb by 28 days, suggesting a threshold for Pb binding or elimination in hemolymph at concentrations near 1000 mu g/g. The Na+, K+-ATPase activity in the gill tissue of mussels was significantly reduced by Pb on day 28 and was highly correlated with tissue Pb concentration (R2 = 0.92; P = 0.013). The Na+, K+-ATPase activity was correlated with reduced hemolymph Na+ concentration at the greatest Pb exposure when enzyme activity was at 30% of controls. Hemolymph Ca2+ concentration increased significantly in mussels from the greatest Pb exposure and may be due to remobilization from the shell in an attempt to buffer the hemolymph against Pb uptake and toxicity. We conclude that Na+, K+-ATPase activity in mussels was adversely affected by Pb exposure, however, because the effects on activity were variable at the lower test concentrations, additional research is warranted over this range of exposures. (C) 2010 Wiley Periodicals, Inc. Environ Toxicol, 2012.

Physiological effects and bioconcentration of triclosan on amphibian larvae.

PubMed

Palenske, Nicole M; Nallani, Gopinath C; Dzialowski, Edward M

2010-08-01

We examined the acute effects of triclosan (TCS) exposure, a common antimicrobial found as a contaminant in the field, on survival and physiology of amphibian larvae. LC50 values were determined after 96h for North American larval species: Acris crepitans blanchardii, Bufo woodhousii woodhousii, Rana sphenocephala, and for a developmental model: Xenopus laevis. Amphibian larvae were most sensitive to TCS exposure during early development based upon 96-h LC50 values. Heart rates for X. laevis and North American larvae exposed to TCS were variable throughout development. Metabolic rates of X. laevis and R. sphenocephala larvae exposed to TCS were significantly affected in larvae exposed to [50% LC50] and [LC50]. Tissue uptake and tissue bioconcentration factor (BCF) of TCS were investigated in X. laevis, B. woodhousii woodhousii, and R. sphenocephala. In general, a significant increase was observed as exposure concentration increased. Tissue BCF values were dependent upon stage and species. While TCS concentrations used here are higher than environmental concentrations, exposure to TCS was dependent upon species and developmental stage, with early developmental stages being most sensitive to TCS exposure. Copyright 2010 Elsevier Inc. All rights reserved.

Effect of increasing CO2 on the terrestrial carbon cycle

PubMed Central

Schimel, David; Fisher, Joshua B.

2015-01-01

Feedbacks from the terrestrial carbon cycle significantly affect future climate change. The CO2 concentration dependence of global terrestrial carbon storage is one of the largest and most uncertain feedbacks. Theory predicts the CO2 effect should have a tropical maximum, but a large terrestrial sink has been contradicted by analyses of atmospheric CO2 that do not show large tropical uptake. Our results, however, show significant tropical uptake and, combining tropical and extratropical fluxes, suggest that up to 60% of the present-day terrestrial sink is caused by increasing atmospheric CO2. This conclusion is consistent with a validated subset of atmospheric analyses, but uncertainty remains. Improved model diagnostics and new space-based observations can reduce the uncertainty of tropical and temperate zone carbon flux estimates. This analysis supports a significant feedback to future atmospheric CO2 concentrations from carbon uptake in terrestrial ecosystems caused by rising atmospheric CO2 concentrations. This feedback will have substantial tropical contributions, but the magnitude of future carbon uptake by tropical forests also depends on how they respond to climate change and requires their protection from deforestation. PMID:25548156

Degradation of propyl paraben by activated persulfate using iron-containing magnetic carbon xerogels: investigation of water matrix and process synergy effects.

PubMed

Metheniti, Maria Evangelia; Frontistis, Zacharias; Ribeiro, Rui S; Silva, Adrián M T; Faria, Joaquim L; Gomes, Helder T; Mantzavinos, Dionissios

2017-10-06

An advanced oxidation process comprising an iron-containing magnetic carbon xerogel (CX/Fe) and persulfate was tested for the degradation of propyl paraben (PP), a contaminant of emerging concern, in various water matrices. Moreover, the effect of 20 kHz ultrasound or light irradiation on process performance was evaluated. The pseudo-first order degradation rate of PP was found to increase with increasing SPS concentration (25-500 mg/L) and decreasing PP concentration (1690-420 μg/L) and solution pH (9-3). Furthermore, the effect of water matrix on kinetics was detrimental depending on the complexity (i.e., wastewater, river water, bottled water) and the concentration of matrix constituents (i.e., humic acid, chloride, bicarbonate). The simultaneous use of CX/Fe and ultrasound as persulfate activators resulted in a synergistic effect, with the level of synergy (between 35 and 50%) depending on the water matrix. Conversely, coupling CX/Fe with simulated solar or UVA irradiation resulted in a cumulative effect in experiments performed in ultrapure water.

Alcohols enhance caerulein-induced zymogen activation in pancreatic acinar cells

PubMed Central

LU, ZHAO; KARNE, SURESH; KOLODECIK, THOMAS; GORELICK, FRED S.

2010-01-01

Activation of zymogens within the pancreatic acinar cell is an early feature of acute pancreatitis. Supraphysiological concentrations of cholecystokinin (CCK) cause zymogen activation and pancreatitis. The effects of the CCK analog, caerulein, and alcohol on trypsin and chymotrypsin activation in isolated pancreatic acini were examined. Caerulein increased markers of zymogen activation in a time- and concentration-dependent manner. Notably, trypsin activity reached a peak value within 30 min, then diminished with time, whereas chymotrypsin activity increased with time. Ethanol (35 mM) sensitized the acinar cells to the effects of caerulein (10−10 to 10−7 M) on zymogen activation but had no effect alone. The effects of ethanol were concentration dependent. Alcohols with a chain length of ≥2 also sensitized the acinar cell to caerulein; the most potent was butanol. Branched alcohols (2-propanol and 2-butanol) were less potent than aliphatic alcohols (1-propanol and 1-butanol). The structure of an alcohol is related to its ability to sensitize acinar cells to the effects of caerulein on zymogen activation. PMID:11842000

Membrane of Candida albicans as a target of berberine.

PubMed

Zorić, Nataša; Kosalec, Ivan; Tomić, Siniša; Bobnjarić, Ivan; Jug, Mario; Vlainić, Toni; Vlainić, Josipa

2017-05-17

We investigated the mechanisms of anti-Candida action of isoquinoline alkaloid berberine, active constituent of medically important plants of Barberry species. The effects on membrane, morphological transition, synthesis of ergosterol and the consequent changes in membrane permeability have been studied. Polarization and lipid peroxidation level of the membrane following berberine treatment have been addressed. Minimal inhibitory concentration (MIC) of berberine against C. albicans was 17.75 μg/mL. Cytotoxic effect of berberine was concentration dependent, and in sub-MIC concentrations inhibit morphological transition of C. albicans cells to its filamentous form. Results showed that berberine affects synthesis of membrane ergosterol dose-dependently and induces increased membrane permeability causing loss of intracellular material to the outer space (DNA/protein leakage). Berberine also caused membrane depolarization and lipid peroxidation of membrane constituents indicating its direct effect on the membrane. Moreover, ROS levels were also increased following berberine treatment indicating further the possibility of membrane damage. Based on the obtained results it seems that berberine achieves its anti-Candida activity by affecting the cell membrane.

The influence of polarizability and charge transfer on specific ion effects in the dynamics of aqueous salt solutions

NASA Astrophysics Data System (ADS)

Nguyen, Mary; Rick, Steven W.

2018-06-01

The diffusion rates for water molecules in salt solutions depend on the identity of the ions, as well as their concentration. Among the alkali metal ions, cesium and potassium increase and sodium strongly decreases the diffusion constant of water. The origin of the difference can be understood by examining the simulation results using different potential models. In this work, aqueous solutions of salts are simulated with a variety of models. Commonly used non-polarizable models, which otherwise reproduce many experimental properties, do not capture the trend in the diffusion constant, while models which include polarization and/or charge transfer interactions do. For the non-polarizable models, the diffusion constant decreases too strongly with salt concentration. The changes in the water diffusion constant with increasing salt concentration match the diffusion constant of the ion. The ion diffusion constant is dependent on the residence time for water in the ion solvation shell. The non-polarizable models over-estimate the residence time, relative to the translational diffusion constant and so tend to under-estimate the ion and water diffusion constants.

Low pH-Induced Pore Formation by the T Domain of Botulinum Toxin Type A is Dependent upon NaCl Concentration

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

Lai, B.; Swaminathan, S.; Agarwal, R.

2010-07-19

Botulinum neurotoxins (BoNTs) undergo low pH-triggered membrane insertion, resulting in the translocation of their light (catalytic) chains into the cytoplasm. The T (translocation) domain of the BoNT heavy chain is believed to carry out translocation. Here, the behavior of isolated T domain from BoNT type A has been characterized, both in solution and when associated with model membranes. When BoNT T domain prepared in the detergent dodecylmaltoside was diluted into aqueous solution, it exhibited a low pH-dependent conformational change below pH 6. At low pH the T domain associated with, and formed pores within, model membrane vesicles composed of 30more » mol% dioleoylphosphatidylglycerol/70 mol% dioleoylphosphatidylcholine. Although T domain interacted with vesicles at low (50 mM) and high (400 mM) NaCl concentrations, the interaction required much less lipid at low salt. However, even at high lipid concentrations pore formation was much more pronounced at low NaCl concentrations than at high NaCl concentration. Increasing salt concentration after insertion in the presence of 50 mM NaCl did not decrease pore formation. A similar effect of NaCl concentration upon pore formation was observed in vesicles composed solely of dioleoylphosphatidylcholine, showing that the effect of NaCl did not solely involve modulation of electrostatic interactions between protein and anionic lipids. These results indicate that some feature of membrane-bound T domain tertiary structure critical for pore formation is highly dependent upon salt concentration.« less

The mitochondrial toxin, 3-nitropropionic acid, induces extracellular Zn2+ accumulation in rat hippocampus slices.

PubMed

Wei, Guo; Hough, Christopher J; Sarvey, John M

2004-11-11

3-nitropropionic acid (3-NPA), a suicide inhibitor of succinate dehydrogenase (SDH; complex II), has been used to provide useful experimental models of Huntington's disease (HD) and "chemical hypoxia" in rodents. The trace ion Zn2+ has been shown to cause neurodegeneration. Employing real-time Newport Green fluorescence imaging of extracellular Zn2+, we found that 3-NPA (10-100 microM) caused a concentration-dependent increase in the concentration of extracellular Zn2+ ([Zn2+]o) in acute rat hippocampus slices. This increase in [Zn2+]o was abolished by 10 mM CaEDTA. The increase of [Zn2+]o was also accompanied by a rapid increase of cytoplasmic-free Zn2+ concentration ([Zn2+]i). The induction of Zn2+ release by 3-MPA in hippocampus slices points to a potential mechanism by which 3-NPA might induce neurodegeneration.

Effect of Si-doping on InAs nanowire transport and morphology

NASA Astrophysics Data System (ADS)

Wirths, S.; Weis, K.; Winden, A.; Sladek, K.; Volk, C.; Alagha, S.; Weirich, T. E.; von der Ahe, M.; Hardtdegen, H.; Lüth, H.; Demarina, N.; Grützmacher, D.; Schäpers, Th.

2011-09-01

The effect of Si-doping on the morphology, structure, and transport properties of nanowires was investigated. The nanowires were deposited by selective-area metal organic vapor phase epitaxy in an N2 ambient. It is observed that doping systematically affects the nanowire morphology but not the structure of the nanowires. However, the transport properties of the wires are greatly affected. Room-temperature four-terminal measurements show that with an increasing dopant supply the conductivity monotonously increases. For the highest doping level the conductivity is higher by a factor of 25 compared to only intrinsically doped reference nanowires. By means of back-gate field-effect transistor measurements it was confirmed that the doping results in an increased carrier concentration. Temperature dependent resistance measurements reveal, for lower doping concentrations, a thermally activated semiconductor-type increase of the conductivity. In contrast, the nanowires with the highest doping concentration show a metal-type decrease of the resistivity with decreasing temperature.

Mineralogical and hydrochemical effects on adsorption removal of cesium-137 and strontium-90 by kaolinite.

PubMed

Jeong, C H

2001-01-01

Adsorption characteristics of the nuclides onto kaolinite were investigated by batch experiment under various pH conditions and concentrations of groundwater cations (Ca2+, Mg2+, K+ and Na+) and anions (HCO3-, CO3(2-) and SO4(2-). Adsorption removal of 137Cs and 90Sr by kaolinite greatly increased as the concentration of groundwater cations increased from 10(-5) to 10(-1) M. In contrast, the pH exerted a small effect on the adsorption of 137Cs and 90Sr onto kaolinite. The zeta potential of kaolinite particles showed a negative increase of amphoteric surface charge with increasing pH. The adsorption behavior of 90Sr was also highly dependent on the concentration of bicarbonate. The thermodynamic saturation index indicated that bicarbonate exerts great effect on strontium adsorption by the precipitation of a strontianite (SrCO3) and a change in pH.

Mg2+ activates the ryanodine receptor type 2 (RyR2) at intermediate Ca2+ concentrations.

PubMed

Chugun, Akihito; Sato, Osamu; Takeshima, Hiroshi; Ogawa, Yasuo

2007-01-01

To clarify whether activity of the ryanodine receptor type 2 (RyR2) is reduced in the sarcoplasmic reticulum (SR) of cardiac muscle, as is the case with the ryanodine receptor type 1 (RyR1), Ca(2+)-dependent [(3)H]ryanodine binding, a biochemical measure of Ca(2+)-induced Ca(2+) release (CICR), was determined using SR vesicle fractions isolated from rabbit and rat cardiac muscles. In the absence of an adenine nucleotide or caffeine, the rat SR showed a complicated Ca(2+) dependence, instead of the well-documented biphasic dependence of the rabbit SR. In the rat SR, [(3)H]ryanodine binding initially increased as [Ca(2+)] increased, with a plateau in the range of 10-100 microM Ca(2+), and thereafter further increased to an apparent peak around 1 mM Ca(2+), followed by a decrease. In the presence of these modulators, this complicated dependence prevailed, irrespective of the source. Addition of 0.3-1 mM Mg(2+) unexpectedly increased the binding two- to threefold and enhanced the affinity for [(3)H]ryanodine at 10-100 microM Ca(2+), resulting in the well-known biphasic dependence. In other words, the partial suppression of RyR2 is relieved by Mg(2+). Ca(2+) could be a substitute for Mg(2+). Mg(2+) also amplifies the responses of RyR2 to inhibitory and stimulatory modulators. This stimulating effect of Mg(2+) on RyR2 is entirely new, and is referred to as the third effect, in addition to the well-known dual inhibitory effects. This effect is critical to describe the role of RyR2 in excitation-contraction coupling of cardiac muscle, in view of the intracellular Mg(2+) concentration.

Influence of cadmium on antioxidant capacity and four microelement concentrations in tomato seedlings (Lycopersicon esculentum).

PubMed

Dong, Jing; Wu, Feibo; Zhang, Guoping

2006-09-01

Tomato (Lycopersicon esculentum) seedlings were grown in four cadmium (Cd) levels of 0-10 microM in a hydroponic system to analyze the antioxidative enzymes, Cd concentration in the plants, and the interaction between Cd and four microelements. The results showed that there was a significant increase in malondialdehyde (MDA) concentration, and superoxide dismutase (SOD) and peroxidase (POD) activities in the plants subjected to 1-10 microM Cd. This indicates that Cd stress induces an oxidative stress response in tomato plants, characterized by an accumulation of MDA and increase in activities of SOD and POD. Root, stem and leaf Cd concentrations increased with its exposure Cd level, and the highest Cd concentration occurred in roots, followed by leaves and stems. A concentration- and tissue-dependent response was found in the four microelement concentrations to Cd stress in the tomato leaves, stems and roots. Regression analysis showed that there was a significantly negative correlation between Cd and Mn, implying the antagonistic effect of Cd on Mn absorption and translocation. The correlation between Cd and Zn, Cu and Fe were inconsistent among leaves, stems and roots.

Alpha-amylase inhibitor, CS-1036 binds to serum amylase in a concentration-dependent and saturable manner.

PubMed

Honda, Tomohiro; Kaneno-Urasaki, Yoko; Ito, Takashi; Kimura, Takako; Matsushima, Nobuko; Okabe, Hiromi; Yamasaki, Atsushi; Izumi, Takashi

2014-03-01

(2R,3R,4R)-4-hydroxy-2-(hydroxymethyl)pyrrolidin-3-yl 4-O-(6-deoxy-β-D-glucopyranosyl)-α-D-glucopyranoside (CS-1036), which is an α-amylase inhibitor, exhibited biphasic and sustained elimination with a long t1/2 (18.4-30.0 hours) in rats and monkeys, but exhibited a short t1/2 (3.7-7.9 hours) in humans. To clarify the species differences in the t1/2, the plasma protein binding of CS-1036 was evaluated by ultrafiltration. A concentration-dependent and saturable plasma protein binding of CS-1036 was observed in rats and monkeys with the dissociation rate constant (KD) of 8.95 and 27.2 nM, and maximal binding capacity (Bmax) of 52.8 and 22.1 nM, respectively. By the assessments of the recombinant amylase and immunoprecipitation, the major binding protein of CS-1036 in rats was identified as salivary amylase (KD 5.64 nM). CS-1036 also showed concentration-dependent and saturable binding to human salivary and pancreatic amylase, with similar binding affinity in rats. However, the protein binding of CS-1036 was constant in human plasma (≤10.2%) due to the lower serum amylase level compared with rats and monkeys. From the calculation of the unbound fraction (fu) in plasma based on in vitro KD and Bmax, the dose-dependent increase in fu after oral administration is speculated to lead to a dose-dependent increase in total body clearance and a high area under the curve/dose at lower doses, such as 0.3 mg/kg in rats.

Effect of overcharge on Li(Ni 0.5Mn 0.3Co 0.2)O 2/Graphite lithium ion cells with poly(vinylidene fluoride) binder. I - Microstructural changes in the anode

DOE PAGES

Dietz Rago, Nancy; Bareno, Javier; Li, Jianlin; ...

2018-03-17

Cells based on NMC/graphite, containing poly(vinylidene difluoride) (PVDF) binders in the positive and negative electrodes, were systematically overcharged to 100, 120, 140, 160, 180, and 250% state-of-charge (SOC). At 250% SOC the cell vented. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) of the anodes showed several state-of-overcharge-dependent trends. Starting at 120% SOC, dendrites appeared and increased in concentration as the SOC increased. Dendrite morphology appeared to be dependent on whether the active material was on the “dull” or “shiny” side of the copper collector. Significantly more delamination of the active material from the collector was seen on themore » “shiny” side of the collector particularly at 180 and 250% SOC. Transition metals were detected at 120% SOC and increased in concentration as the SOC increased. Finally, there was considerable spatial heterogeneity in the microstructures across each laminate with several regions displaying complex layered structures.« less

Enhanced energy harvesting by concentration gradient-driven ion transport in SBA-15 mesoporous silica thin films.

PubMed

Hwang, Junho; Kataoka, Sho; Endo, Akira; Daiguji, Hirofumi

2016-09-21

Nanofluidic energy harvesting systems have attracted interest in the field of battery application, particularly for miniaturized electrical devices, because they possess excellent energy conversion capability for their size. In this study, a mesoporous silica (MPS)-based nanofluidic energy harvesting system was fabricated and selective ion transport in mesopores as a function of the salt gradient was investigated. Aqueous solutions with three different kinds of monovalent electrolytes-KCl, NaCl, and LiCl-with different diffusion coefficients (D + ) were considered. The highest power density was 3.90 W m -2 for KCl, followed by 2.39 W m -2 for NaCl and 1.29 W m -2 for LiCl. Furthermore, the dependency of power density on the type of cation employed indicates that the harvested energy increases as the cation mobility increases, particularly at high concentrations. This cation-specific dependency suggests that the maximum power density increases by increasing the diffusion coefficient ratio of cations to anions, making this ratio a critical parameter in enhancing the performance of nanofluidic energy harvesting systems with extremely small pores ranging from 2 to 3 nm.

Effect of overcharge on Li(Ni 0.5Mn 0.3Co 0.2)O 2/Graphite lithium ion cells with poly(vinylidene fluoride) binder. I - Microstructural changes in the anode

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

Dietz Rago, Nancy; Bareno, Javier; Li, Jianlin

Cells based on NMC/graphite, containing poly(vinylidene difluoride) (PVDF) binders in the positive and negative electrodes, were systematically overcharged to 100, 120, 140, 160, 180, and 250% state-of-charge (SOC). At 250% SOC the cell vented. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) of the anodes showed several state-of-overcharge-dependent trends. Starting at 120% SOC, dendrites appeared and increased in concentration as the SOC increased. Dendrite morphology appeared to be dependent on whether the active material was on the “dull” or “shiny” side of the copper collector. Significantly more delamination of the active material from the collector was seen on themore » “shiny” side of the collector particularly at 180 and 250% SOC. Transition metals were detected at 120% SOC and increased in concentration as the SOC increased. Finally, there was considerable spatial heterogeneity in the microstructures across each laminate with several regions displaying complex layered structures.« less

The GLP-1 mimetic exenatide potentiates insulin secretion in healthy cats.

PubMed

Gilor, C; Graves, T K; Gilor, S; Ridge, T K; Rick, M

2011-07-01

The glucagon-like peptide-1 mimetic exenatide has a glucose-dependent insulinotropic effect, and it is effective in controlling blood glucose (BG) with minimal side effects in people with type 2 diabetes. Exenatide also delays gastric emptying, increases satiety, and improves β-cell function. We studied the effect of exenatide on insulin secretion during euglycemia and hyperglycemia in cats. Nine young, healthy, neutered, purpose-bred cats were used in a randomized, cross-over design. BG concentrations during an oral glucose tolerance test were determined in these cats previously. Two isoglycemic glucose clamps (mimicking the BG concentration during the oral glucose tolerance test) were performed in each cat on separate days, one without prior treatment (IGC) and the second with exenatide (1 μg/kg) injected subcutaneously 2 h before (ExIGC). BG, insulin, and exenatide concentrations were measured, and glucose infusion rates were recorded and compared in paired tests between the two experiments. After exenatide injection, insulin serum concentrations increased significantly (2.4-fold; range 1.0- to 9.2-fold; P = 0.004) within 15 min. This was followed by a mild decrease in BG concentration and a return of insulin concentration to baseline despite a continuous increase in serum exenatide concentrations. Insulin area under the curve (AUC) during ExIGC was significantly higher than insulin AUC during IGC (AUC ratio, 2.0 ± 0.4; P = 0.03). Total glucose infused was not significantly different between IGC and ExIGC. Exenatide was detectable in plasma at 15 min after injection. The mean exenatide concentration peaked at 45 min and then returned to baseline by 75 min. Exenatide was still detectable in the serum of three of five cats 8 h after injection. No adverse reactions to exenatide were observed. In conclusion, exenatide affects insulin secretion in cats in a glucose-dependent manner, similar to its effect in other species. Although this effect was not accompanied by a greater ability to dispose of an intravenous glucose infusion, other potentially beneficial effects of exenatide on pancreatic β cells, mainly increasing their proliferation and survival, should be investigated in cats. Copyright © 2011 Elsevier Inc. All rights reserved.

Feedforward activation of endothelial ENaC by high sodium

PubMed Central

Korte, Stefanie; Sträter, Alexandra S.; Drüppel, Verena; Oberleithner, Hans; Jeggle, Pia; Grossmann, Claudia; Fobker, Manfred; Nofer, Jerzy-Roch; Brand, Eva; Kusche-Vihrog, Kristina

2014-01-01

Kidney epithelial sodium channels (ENaCs) are known to be inactivated by high sodium concentrations (feedback inhibition). Recently, the endothelial sodium channel (EnNaC) was identified to control the nanomechanical properties of the endothelium. EnNaC-dependent endothelial stiffening reduces the release of nitric oxide, the hallmark of endothelial dysfunction. To study the regulatory impact of sodium on EnNaC, endothelial cells (EA.hy926 and ex vivo mouse endothelium) were incubated in aldosterone-free solutions containing either low (130 mM) or high (150 mM) sodium concentrations. By applying atomic force microscopy-based nanoindentation, an unexpected positive correlation between increasing sodium concentrations and cortical endothelial stiffness was observed, which can be attributed to functional EnNaC. In particular, an acute rise in sodium concentration (+20 mM) was sufficient to increase EnNaC membrane abundance by 90% and stiffening of the endothelial cortex by 18%. Despite the absence of exogenous aldosterone, these effects were prevented by the aldosterone synthase inhibitor FAD286 (100 nM) or the mineralocorticoid receptor (MR)-antagonist spironolactone (100 nM), indicating endogenous aldosterone synthesis and MR-dependent signaling. Interestingly, in the presence of high-sodium concentrations, FAD286 increased the transcription of the MR by 69%. Taken together, a novel feedforward activation of EnNaC by sodium is proposed that contrasts ENaC feedback inhibition in kidney.—Korte, S., Sträter, A. S., Drüppel, V., Oberleithner, H., Jeggle, P., Grossmann, C., Fobker, M., Nofer, J.-R., Brand, E., Kusche-Vihrog, K. Feedforward activation of endothelial ENaC by high sodium. PMID:24868010

Studies on the concentration dependence of specific rotation of Alpha lactose monohydrate (α-LM) aqueous solutions and growth of α-LM single crystals

NASA Astrophysics Data System (ADS)

Vinodhini, K.; Divya Bharathi, R.; Srinivasan, K.

2018-02-01

Lactose is an optically active substance. As it is one of the reducing sugars, exhibits mutarotation in solution when it dissolves in any solvent. In solution, lactose exists in two isomeric forms, alpha-Lactose (α-L) and beta-lactose (β-L) through the mutarotation reaction. Mutarotation produces a dynamic equilibrium between two isomers in a solution and kinetics of this process determines the growth rate of alpha lactose monohydrate (α-LM) crystals. Since no data were available on the specific rotation of aqueous α-LM solutions at different concentrations at 33 °C, the initial experiments were carried out on the specific rotation of aqueous α-LM solutions at different concentrations at 33 °C. The specific rotations of the solutions were decreased with increasing time through the mutarotation reaction. The initial and final (equilibrium) specific rotations of the solutions were determined by using automatic digital polarimeter. The compositions of α and β-L in all prepared solutions were calculated from initial and final optical rotations by the method of Sharp and Doob. The composition of α-L decreased whereas, the composition of β-L increased in solutions with increasing concentration of α-LM at 33 °C. Experimental results revealed that this method could be easily and safely employed to study the dependence of specific rotation of solutions on their concentration. The effect of β-lactose on the morphology of nucleated α-LM single crystals has been studied at different experimental conditions.

Tributyltin-induced endoplasmic reticulum stress and its Ca(2+)-mediated mechanism.

PubMed

Isomura, Midori; Kotake, Yaichiro; Masuda, Kyoichi; Miyara, Masatsugu; Okuda, Katsuhiro; Samizo, Shigeyoshi; Sanoh, Seigo; Hosoi, Toru; Ozawa, Koichiro; Ohta, Shigeru

2013-10-01

Organotin compounds, especially tributyltin chloride (TBT), have been widely used in antifouling paints for marine vessels, but exhibit various toxicities in mammals. The endoplasmic reticulum (ER) is a multifunctional organelle that controls post-translational modification and intracellular Ca(2+) signaling. When the capacity of the quality control system of ER is exceeded under stress including ER Ca(2+) homeostasis disruption, ER functions are impaired and unfolded proteins are accumulated in ER lumen, which is called ER stress. Here, we examined whether TBT causes ER stress in human neuroblastoma SH-SY5Y cells. We found that 700nM TBT induced ER stress markers such as CHOP, GRP78, spliced XBP1 mRNA and phosphorylated eIF2α. TBT also decreased the cell viability both concentration- and time-dependently. Dibutyltin and monobutyltin did not induce ER stress markers. We hypothesized that TBT induces ER stress via Ca(2+) depletion, and to test this idea, we examined the effect of TBT on intracellular Ca(2+) concentration using fura-2 AM, a Ca(2+) fluorescent probe. TBT increased intracellular Ca(2+) concentration in a TBT-concentration-dependent manner, and Ca(2+) increase in 700nM TBT was mainly blocked by 50μM dantrolene, a ryanodine receptor antagonist (about 70% inhibition). Dantrolene also partially but significantly inhibited TBT-induced GRP78 expression and cell death. These results suggest that TBT increases intracellular Ca(2+) concentration by releasing Ca(2+) from ER, thereby causing ER stress. Copyright © 2013 Elsevier Inc. All rights reserved.

Neurobehavioral effects during experimental exposure to 1-octanol and isopropanol.

PubMed

van Thriel, Christoph; Kiesswetter, Erns; Blaszkewicz, Meinolf; Golka, Klaus; Seeber, Andreas

2003-04-01

The study examined acute neurobehavioral effects provoked by controlled exposure to 1-octanol and isopropanol among male volunteers. In a 29-m3 exposure laboratory, 24 male students (mean age 25.8 years) were exposed to 1-octanol and isopropanol. Each substance was used in two concentrations (0.1 and 6.4 ppm for 1-octanol; 34.9 and 189.9 ppm for isopropanol:). In a crossover design, each subject was exposed for 4 hours to the conditions. Twelve subjects reported enhanced chemical sensitivity; the other 12 were age-matched controls. At the onset and end of the exposures neurobehavioral tests were administered and symptoms were rated. At the end of the high and low isopropanol exposures the tiredness ratings were elevated, but no dose-dependence could be confirmed. For both substances and concentrations, the annoyance ratings increased during the exposure, but only for isopropanol did the increase show a dose-response relation. The subjects reported olfactory symptoms during the exposure to the high isopropanol and both 1-octanol concentrations. Isopropanol provoked no sensory irritation, whereas high 1-octanol exposure slightly enhanced it. Only among the subjects with enhanced chemical sensitivity were both 1-octanol concentrations associated with a stronger increase in annoyance, and lower detection rates were observed in a divided attention task. Previous studies reporting no neurobehavioral effects for isopropanol (up to 400 ppm) were confirmed. The results obtained for 1-octanol lacked dose-dependency, and their evaluation, is difficult. The annoying odor of 1-octanol may mask sensory irritation and prevent subjects with enhanced chemical sensitivity from concentrating on performance in a demanding task.

Drosophila melanogaster as a model system of aluminum toxicity and aging.

PubMed

Kijak, Ewelina; Rosato, Ezio; Knapczyk, Katarzyna; Pyza, Elżbieta

2014-04-01

The aim of this study was to investigate the toxic effects of aluminum (Al) on the model organism-Drosophila melanogaster. The study is especially concerned with the effects of aluminum on the fruit fly's development, life span, and circadian rhythm in rest and activity. Flies were exposed to aluminum in concentrations from 40 to 280 mg/kg in rearing media or the flies were raised on control medium. Moreover, the life span of insects exposed to aluminum containing 40, 120, or 240 mg/kg of Al in the medium, only during their larval development, during the whole life cycle and only in their adult life was tested. To check if aluminum and aging cause changes in D. melanogaster behavior, the locomotor activity of flies at different ages was recorded. Results showed that aluminum is toxic in concentrations above 160 mg/kg in the rearing medium. Depending on Al concentration and time of exposure, the life span of the flies was shortened. At intermediate concentrations (120 mg/kg), however, Al had a stimulating effect on males increasing their life span and level of locomotor activity. At higher concentration the aluminum exposure increased or decreased the level of locomotor activity of D. melanogaster depending on age of flies. In addition, in the oldest insects reared on aluminum supplemented media and in mid-aged flies reared on the highest concentration of Al the daily rhythm of activity was disrupted. © 2013 Institute of Zoology, Chinese Academy of Sciences.

Long-range electrostatic screening in ionic liquids

PubMed Central

Gebbie, Matthew A.; Dobbs, Howard A.; Valtiner, Markus; Israelachvili, Jacob N.

2015-01-01

Electrolyte solutions with high concentrations of ions are prevalent in biological systems and energy storage technologies. Nevertheless, the high interaction free energy and long-range nature of electrostatic interactions makes the development of a general conceptual picture of concentrated electrolytes a significant challenge. In this work, we study ionic liquids, single-component liquids composed solely of ions, in an attempt to provide a novel perspective on electrostatic screening in very high concentration (nonideal) electrolytes. We use temperature-dependent surface force measurements to demonstrate that the long-range, exponentially decaying diffuse double-layer forces observed across ionic liquids exhibit a pronounced temperature dependence: Increasing the temperature decreases the measured exponential (Debye) decay length, implying an increase in the thermally driven effective free-ion concentration in the bulk ionic liquids. We use our quantitative results to propose a general model of long-range electrostatic screening in ionic liquids, where thermally activated charge fluctuations, either free ions or correlated domains (quasiparticles), take on the role of ions in traditional dilute electrolyte solutions. This picture represents a crucial step toward resolving several inconsistencies surrounding electrostatic screening and charge transport in ionic liquids that have impeded progress within the interdisciplinary ionic liquids community. More broadly, our work provides a previously unidentified way of envisioning highly concentrated electrolytes, with implications for diverse areas of inquiry, ranging from designing electrochemical devices to rationalizing electrostatic interactions in biological systems. PMID:26040001

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

Dholabhai, Pratik P., E-mail: pratik.dholabhai@asu.ed; Anwar, Shahriar, E-mail: anwar@asu.ed; Adams, James B., E-mail: jim.adams@asu.ed

Kinetic lattice Monte Carlo (KLMC) model is developed for investigating oxygen vacancy diffusion in praseodymium-doped ceria. The current approach uses a database of activation energies for oxygen vacancy migration, calculated using first-principles, for various migration pathways in praseodymium-doped ceria. Since the first-principles calculations revealed significant vacancy-vacancy repulsion, we investigate the importance of that effect by conducting simulations with and without a repulsive interaction. Initially, as dopant concentrations increase, vacancy concentration and thus conductivity increases. However, at higher concentrations, vacancies interfere and repel one another, and dopants trap vacancies, creating a 'traffic jam' that decreases conductivity, which is consistent with themore » experimental findings. The modeled effective activation energy for vacancy migration slightly increased with increasing dopant concentration in qualitative agreement with the experiment. The current methodology comprising a blend of first-principle calculations and KLMC model provides a very powerful fundamental tool for predicting the optimal dopant concentration in ceria related materials. -- graphical abstract: Ionic conductivity in praseodymium doped ceria as a function of dopant concentration calculated using the kinetic lattice Monte Carlo vacancy-repelling model, which predicts the optimal composition for achieving maximum conductivity. Display Omitted Research highlights: {yields} KLMC method calculates the accurate time-dependent diffusion of oxygen vacancies. {yields} KLMC-VR model predicts a dopant concentration of {approx}15-20% to be optimal in PDC. {yields} At higher dopant concentration, vacancies interfere and repel one another, and dopants trap vacancies. {yields} Activation energy for vacancy migration increases as a function of dopant content« less

The role of phytoplankton composition, biomass and cell volume in accumulation and transfer of endocrine disrupting compounds in the Southern Baltic Sea (The Gulf of Gdansk).

PubMed

Staniszewska, Marta; Nehring, Iga; Zgrundo, Aleksandra

2015-12-01

Endocrine disrupting compounds (EDCs) like bisphenol A (BPA), 4-tert-octylphenol (OP) and 4-nonylphenol (NP) are introduced to the trophic webs through among others phytoplankton. This paper describes BPA, OP and NP concentrations in phytoplankton in the Gulf of Gdansk (Southern Baltic Sea) in the years 2011-2012. The assays of BPA, OP and NP in samples were performed using HPLC with fluorescence detection. The concentrations of BPA, the most commonly used of the three compounds, were over ten times higher than OP and NP concentrations. The concentrations of the studied EDCs in phytoplankton from the Gulf of Gdansk depended on anthropogenic factors and on phytoplankton properties (species composition, biomass, volume). An increase in phytoplankton biomass did not always result in an increase of BPA, OP and NP concentrations. However, the load of the studied EDCs accumulated in phytoplankton biomass increase with a rise of biomass. An increase in BPA, OP and NP concentrations was effected by biomass growth and the proportions ofciliates, dinoflagellates, diatoms and green algae. A strong positive correlation between OP and NP concentrations and negative correlation between BPA concentrations and biomass of organisms with cells measuring <1000 μm(3) in volume results from the differing properties of these compounds. Copyright © 2015 Elsevier Ltd. All rights reserved.

The dose-dependent effects of chronic iron overload on the production of oxygen free radicals and vitamin E concentrations in the liver of a murine model.

PubMed

McCullough, Karey D; Bartfay, Wally J

2007-04-01

Genetic disorders of iron metabolism such as primary and secondary hemochromatosis affect thousands of individuals worldwide and are major causes of liver dysfunction, morbidity, and mortality. Although the exact mechanism of hepatic injury associated with these genetic disorders is not fully understood, the propagation of excess concentrations of iron-catalyzed oxygen free radicals (OFRs) may play a role. The authors hypothesized that chronic iron burden would result in dose-dependent (a) increases in hepatic iron stores, (b) increases in hepatic OFR-mediated hepatic cellular injury as quantified by the cytotoxic aldehydes malondialdehyde (MDA) and hexanal, and (c) decreases in protective antioxidant reserve status as quantified by plasma vitamin E (alpha-tocopherol) levels in a murine model. Twenty B(6)D(2)F1 male mice were randomized to the (a) saline control (0.05 mL intraperiotoneal [i.p.]/mouse/day, n = 5), (b) 100 mg total iron burden (n = 5), (c) 200 mg total iron burden (n = 5), or (d) 400 mg total iron burden (n = 5) group. Iron burden was achieved by daily injections of iron dextran (Imferon, 0.05 mL i.p./mouse/day). In comparison to control mice and in support of the hypothesis, the authors observed significant dose-dependent increases in total hepatic iron burden (p < .001) with corresponding increases in MDA and hexanal concentrations (p < .001) and decreases in the protective plasma antioxidant vitamin E (p < .001). These findings suggest that iron-catalyzed OFR-mediated damage may play a role in damaging the liver in chronic states of iron burden.

Impact of arachidonic versus eicosapentaenoic acid on exotonin-induced lung vascular leakage: relation to 4-series versus 5-series leukotriene generation.

PubMed

Grimminger, F; Wahn, H; Mayer, K; Kiss, L; Walmrath, D; Seeger, W

1997-02-01

Escherichia coli hemolysin (HlyA) is a proteinaceous pore-forming exotoxin that is implicated as a significant pathogenicity factor in extraintestinal E. coli infections including sepsis. In perfused rabbit lungs, subcytolytic concentrations of the toxin evoke thromboxane-mediated vasoconstriction and prostanoid-independent protracted vascular permeability increase (11). In the present study, the influence of submicromolar concentrations of free arachidonic acid (AA) and eicosapentaenoic acid (EPA) on the HlyA-induced leakage response was investigated. HlyA at concentration from 0.02 to 0.06 hemolytic units/ml provoked a dose-dependent, severalfold increase in the capillary filtration coefficient (Kfc), accompanied by the release of leukotriene(LT)B4, LTC4, and LTE4 into the recirculating buffer fluid. Simultaneous application of 100 nmol/L AA markedly augmented the HlyA-elicited leakage response, concomitant with an amplification of LTB4 release and a change in the kinetics of cysteinyl-LT generation. In contrast, 50 to 200 nmol/L EPA suppressed in a dose-dependent manner the HlyA-induced increase in Kfc values. This was accompanied by a blockage of 4-series LT generation and a dose-dependent appearance of LTB5, LTC5, and LTE5. In addition, EPA fully antagonized the AA-induced amplification of the HlyA-provoked Kfc increase, again accompanied by a shift from 4-series to 5-series LT generation. We conclude that the vascular leakage provoked by HlyA in rabbit lungs is differentially influenced by free AA versus free EPA, related to the generation of 4- versus 5-series leukotrienes. The composition of lipid emulsions used for parenteral nutrition may thus influence inflammatory capillary leakage.

Endogenous flow of amino acids in the avian ileum as influenced by increasing dietary peptide concentrations.

PubMed

Ravindran, Velmurugu; Morel, Patrick C H; Rutherfurd, Shane M; Thomas, Donald V

2009-03-01

The aim of the present study was to establish whether feeding broiler chickens with diets containing increasing dietary peptide concentrations would cause increases in ileal endogenous amino acid flow. The flow of N and most amino acids increased quadratically (P < 0.05 to 0.001) with increasing dietary concentrations of peptides. The exceptions were the flow of threonine, serine, glycine, tyrosine and cystine, which increased linearly (P < 0.001) with dietary peptide levels. Another notable exception to the general trend was the flow of proline, which was significantly higher (P < 0.01) in birds fed the protein-free diet. The amino acid profile of endogenous protein, expressed as proportion of crude protein, indicated that the ratios of threonine, glutamic acid, proline, glycine, leucine, histidine, arginine and cystine were influenced (P < 0.05) with increasing dietary peptide concentrations. In general, compared with the protein-free diet, the ratios of threonine and arginine in endogenous protein were lower (P < 0.05) and those of glutamic acid, glycine and histidine were greater (P < 0.05) in diets with high concentrations of peptides. The ratio of proline was found to decrease (P < 0.05) with increasing dietary peptide concentrations. These changes in the amino acid profile of endogenous protein are probably reflective of changes in the output of one or more of the components of endogenous protein. Overall, the present results demonstrated that increasing dietary peptide concentrations increased the flow of endogenous amino acid flow at the terminal ileum of broiler chickens in a dose-dependent manner and also caused changes in the composition of endogenous protein. The observed changes in endogenous amino flow will influence the maintenance requirements for amino acids and also have implications for the calculation of true digestibility coefficient of feedstuffs.

Phenomenological model of photoluminescence degradation and photoinduced defect formation in silicon nanocrystal ensembles under singlet oxygen generation

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

Gongalsky, Maxim B., E-mail: mgongalsky@gmail.com; Timoshenko, Victor Yu.

2014-12-28

We propose a phenomenological model to explain photoluminescence degradation of silicon nanocrystals under singlet oxygen generation in gaseous and liquid systems. The model considers coupled rate equations, which take into account the exciton radiative recombination in silicon nanocrystals, photosensitization of singlet oxygen generation, defect formation on the surface of silicon nanocrystals as well as quenching processes for both excitons and singlet oxygen molecules. The model describes well the experimentally observed power law dependences of the photoluminescence intensity, singlet oxygen concentration, and lifetime versus photoexcitation time. The defect concentration in silicon nanocrystals increases by power law with a fractional exponent, whichmore » depends on the singlet oxygen concentration and ambient conditions. The obtained results are discussed in a view of optimization of the photosensitized singlet oxygen generation for biomedical applications.« less

Scaling Theory of Polyelectrolyte Nanogels

NASA Astrophysics Data System (ADS)

Qu, Li-Jian

2017-08-01

The present paper develops the scaling theory of polyelectrolyte nanogels in dilute and semidilute solutions. The dependencies of the nanogel dimension on branching topology, charge fraction, subchain length, segment number, solution concentration are obtained. For a single polyelectrolyte nanogel in salt free solution, the nanogel may be swelled by the Coulombic repulsion (the so-called polyelectrolyte regime) or the osmotic counterion pressure (the so-called osmotic regime). Characteristics and boundaries between different regimes of a single polyelectrolyte nanogel are summarized. In dilute solution, the nanogels in polyelectrolyte regime will distribute orderly with the increase of concentration. While the nanogels in osmotic regime will always distribute randomly. Different concentration dependencies of the size of a nanogel in polyelectrolyte regime and in osmotic regime are also explored. Supported by China Earthquake Administration under Grant No. 20150112 and National Natural Science Foundation of China under Grant No. 21504014

Acoustically levitated droplets: a contactless sampling method for fluorescence studies.

PubMed

Leiterer, Jork; Grabolle, Markus; Rurack, Knut; Resch-Genger, Ute; Ziegler, Jan; Nann, Thomas; Panne, Ulrich

2008-01-01

Acoustic levitation is used as a new tool to study concentration-dependent processes in fluorescence spectroscopy. With this technique, small amounts of liquid and solid samples can be measured without the need for sample supports or containers, which often limits signal acquisition and can even alter sample properties due to interactions with the support material. We demonstrate that, because of the small sample volume, fluorescence measurements at high concentrations of an organic dye are possible without the limitation of inner-filter effects, which hamper such experiments in conventional, cuvette-based measurements. Furthermore, we show that acoustic levitation of liquid samples provides an experimentally simple way to study distance-dependent fluorescence modulations in semiconductor nanocrystals. The evaporation of the solvent during levitation leads to a continuous increase of solute concentration and can easily be monitored by laser-induced fluorescence.

The complexity of minocycline serum protein binding.

PubMed

Zhou, Jian; Tran, Brian T; Tam, Vincent H

2017-06-01

Serum protein binding is critical for understanding the pharmacology of antimicrobial agents. Tigecycline and eravacycline were previously reported to have atypical non-linear protein binding; the percentage of free fraction decreased with increasing total concentration. In this study, we extended the investigation to other tetracyclines and examined the factors that might impact protein binding. Different minocycline concentrations (0.5-50 mg/L) and perfusion media (saline, 0.1 M HEPES buffer and 0.1 and 1 M PBS) were examined by in vitro microdialysis. After equilibration, two dialysate samples were taken from each experiment and the respective antimicrobial agent concentrations were analysed by validated LC-MS/MS methods. For comparison, the serum protein bindings of doxycycline and levofloxacin were also determined. The free fraction of minocycline decreased with increasing total concentration, and the results depended on the perfusion media used. The trends of minocycline protein binding in mouse and human sera were similar. In addition, serum protein binding of doxycycline showed the same concentration-dependent trend as minocycline, while the results of levofloxacin were concentration independent. The serum protein bindings of minocycline and doxycycline are negatively correlated with their total concentrations. It is possible that all tetracyclines share the same pharmacological property. Moreover, the specific perfusion media used could also impact the results of microdialysis. Additional studies are warranted to understand the mechanism(s) and clinical implications of serum protein binding of tetracyclines. © The Author 2017. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Chemical-exchange-saturation-transfer magnetic resonance imaging to map gamma-aminobutyric acid, glutamate, myoinositol, glycine, and asparagine: Phantom experiments

NASA Astrophysics Data System (ADS)

Oh, Jang-Hoon; Kim, Hyug-Gi; Woo, Dong-Cheol; Jeong, Ha-Kyu; Lee, Soo Yeol; Jahng, Geon-Ho

2017-03-01

The physical and technical development of chemical-exchange-saturation-transfer (CEST) magnetic resonance imaging (MRI) using clinical 3 T MRI was explored with the goal of mapping asparagine (Asn), gamma-aminobutyric acid (GABA), glutamate (Glu), glycine (Gly), and myoinositol (MI), which exist in the brain. Phantoms with nine different conditions at concentrations of 10, 30, and 50 mM and pH values of 5.6, 6.2, and 7.4 were prepared for the five target molecules to evaluate the dependence of the CEST effect in the concentration, the pH, and the amplitude of the applied radiofrequency field B1. CEST images in the offset frequency range of ±6 parts per million (ppm) were acquired using a pulsed radio-frequency saturation scheme with a clinical 3 T MRI system. A voxel-based main magnetic field B0 inhomogeneity correction, where B0 is the center frequency offset at zero ppm, was performed by using the spline interpolation method to fit the full Z-spectrum to estimate the center frequency. A voxel-based CEST asymmetry map was calculated to evaluate amide (-NH), amine (-NH2), and hydroxyl (-OH) groups for the five target molecules. The CEST effect for Glu, GABA, and Gly clearly increased with increasing concentrations. The CEST effect for MI was minimal, with no noticeable differences at different concentrations. The CEST effect for Glu and Gly increased with increasing acidity. The highest CEST asymmetry for GABA was observed at pH 6.2. The CEST effect for Glu, GABA, and Gly increased with increasing B1 amplitude. For all target molecules, the CEST effect for the human 3 T MRI system increased with increasing concentration and B1 amplitude, but varied with pH, depending on the characteristics of the molecules. The CEST effect for MI may be not suitable with clinical MRI systems. These results show that CEST imaging in the brain with the amine protons by using 3 T MRI is possible for several neuronal diseases.

Comparison of high MRI T1 signals with manganese concentration in brains of cynomolgus monkeys after 8 months of stainless steel welding-fume exposure.

PubMed

Park, Jung Duck; Chung, Yong Hyun; Kim, Choong Yong; Ha, Chang Soo; Yang, Seoung Oh; Khang, Hyun Soo; Yu, In Kyu; Cheong, Hae Kwan; Lee, Jong Seong; Song, Chang-Woo; Kwon, Il Hoon; Han, Jeong Hee; Sung, Jae Hyuck; Heo, Jeong Doo; Choi, Byung Sun; Im, Ruth; Jeong, Jayoung; Yu, Il Je

2007-09-01

Several pharmacokinetic studies on inhalation exposure to manganese (Mn) have already demonstrated that Mn readily accumulates in the olfactory and brain regions. However, a shortening of the magnetic resonance imaging (MRI) T1 relaxation time or high T1 signal intensity in specific sites of the brain, including the globus pallidus and subcortical frontal white matter, as indicative of tissue manganese accumulation has not yet been clearly established for certain durations of known doses of welding-fume exposure in experimental animals. Accordingly, to investigate the movement of manganese after welding-fume exposure, six cynomolgus monkeys were acclimated and assigned to three dose groups: unexposed, low dose (31 mg/m(3) total suspended particulate [TSP], 0.9 mg/m(3) of Mn), and high dose (62 mg/m(3) TSP, 1.95 mg/m(3) of Mn) of total suspended particulate. The primates were exposed to manual metal arc stainless steel (MMA-SS) welding fumes for 2 h per day in an inhalation chamber system equipped with an automatic fume generator. Magnetic resonance imaging (MRI) studies were conducted before the initiation of exposure and thereafter every month. The tissue Mn concentrations were then measured after a plateau was reached regarding the shortening of the MRI T1 relaxation time. A dose-dependent increase in the Mn concentration was found in the lungs, while noticeable increases in the Mn concentrations were found in certain tissues, such as the liver, kidneys, and testes. Slight increases in the Mn concentrations were found in the caudate, putamen, frontal lobe, and substantia nigra, while a dose-dependent noticeable increase was only found in the globus pallidus. Therefore, the present results indicated that a shortening of the MRI T1 relaxation time corresponded well with the Mn concentration in the globus pallidus after prolonged welding-fume exposure.

Preparation and characterization of hydroxyapatite/gelatin composite membranes for immunoisolation

NASA Astrophysics Data System (ADS)

Chen, Jyh-Ping; Chang, Feng-Nian

2012-12-01

Composite membranes are fabricated from hydroxyapatite (HAP) and gelatin for immunoisolation of cells. The films were fabricated by crosslinking 5 wt%, 10 wt%, and 20 wt% gelatin with 1 wt% glutaraldehyde (GA) in the presence of HAP. Fourier transform infrared spectroscopy analysis confirms imide bond formation between GA and gelatin, while the crystal structure of HAP powder remains unchanged from X-ray diffraction analysis. The degree of crosslinking depends on crosslinking time and gelatin concentration. For 5% and 10% gelatin, the degree of crosslinking levels off at 90% within 48 h. From scanning electron microscopy micrographs, the microstructure of the composite membrane depends on the amount of gelatin used in the crosslinking reaction. The mechanical strength of the composite membrane could be enhanced by increasing the gelatin concentration. BET analysis indicates that pore size of the micropores on the surface HAP/gelatin agglomerates decreases with increasing gelatin concentration. However, the macropore, through which diffusion of molecules occurs, is larger at higher gelatin concentrations. The permeability coefficients of different molecules through a HAP/gelatin composite membrane increase with increasing gelatin concentration and is inversely correlated with the molecular weight of the molecule. For immunoisolation of cells, the diffusion of large molecules stimulated by the immune system can be rejected by a chamber constructed from the HAP/gelatin membrane. Insulinoma cells were encapsulated in alginate-poly-L-lysine-alginate microcapsules and enclosed in a HAP/gelatin chamber. The chamber did not impair the viability and function of insulinoma cells and cells can secrete insulin in response to glucose concentration change. The chamber is therefore useful for the physiologically controlled secretion of insulin in response to the blood glucose level. Intraperitoneal transplantation of the chamber into streptozotocin-induced diabetic SD rats could maintain normal blood glucose levels in test animals for up to 60 days without immunosuppression.

Effects of 3-day bed rest on physiological responses to graded exercise in athletes and sedentary men

NASA Technical Reports Server (NTRS)

Smorawinski, J.; Nazar, K.; Kaciuba-Uscilko, H.; Kaminska, E.; Cybulski, G.; Kodrzycka, A.; Bicz, B.; Greenleaf, J. E.

2001-01-01

To test the hypotheses that short-term bed-rest (BR) deconditioning influences metabolic, cardiorespiratory, and neurohormonal responses to exercise and that these effects depend on the subjects' training status, 12 sedentary men and 10 endurance- and 10 strength-trained athletes were submitted to 3-day BR. Before and after BR they performed incremental exercise test until volitional exhaustion. Respiratory gas exchange and heart rate (HR) were recorded continuously, and stroke volume (SV) was measured at submaximal loads. Blood was taken for lactate concentration ([LA]), epinephrine concentration ([Epi]), norepinephrine concentration ([NE]), plasma renin activity (PRA), human growth hormone concentration ([hGH]), testosterone, and cortisol determination. Reduction of peak oxygen uptake (VO(2 peak)) after BR was greater in the endurance athletes than in the remaining groups (17 vs. 10%). Decrements in VO(2 peak) correlated positively with the initial values (r = 0.73, P < 0.001). Resting and exercise respiratory exchange ratios were increased in athletes. Cardiac output was unchanged by BR in all groups, but exercise HR was increased and SV diminished in the sedentary subjects. The submaximal [LA] and [LA] thresholds were decreased in the endurance athletes from 71 to 60% VO(2 peak) (P < 0.001); they also had an earlier increase in [NE], an attenuated increase in [hGH], and accentuated PRA and cortisol elevations during exercise. These effects were insignificant in the remaining subjects. In conclusion, reduction of exercise performance and modifications in neurohormonal response to exercise after BR depend on the previous level and mode of physical training, being the most pronounced in the endurance athletes.

Effects of 3-day bed rest on physiological responses to graded exercise in athletes and sedentary men.

PubMed

Smorawiński, J; Nazar, K; Kaciuba-Uscilko, H; Kamińska, E; Cybulski, G; Kodrzycka, A; Bicz, B; Greenleaf, J E

2001-07-01

To test the hypotheses that short-term bed-rest (BR) deconditioning influences metabolic, cardiorespiratory, and neurohormonal responses to exercise and that these effects depend on the subjects' training status, 12 sedentary men and 10 endurance- and 10 strength-trained athletes were submitted to 3-day BR. Before and after BR they performed incremental exercise test until volitional exhaustion. Respiratory gas exchange and heart rate (HR) were recorded continuously, and stroke volume (SV) was measured at submaximal loads. Blood was taken for lactate concentration ([LA]), epinephrine concentration ([Epi]), norepinephrine concentration ([NE]), plasma renin activity (PRA), human growth hormone concentration ([hGH]), testosterone, and cortisol determination. Reduction of peak oxygen uptake (VO(2 peak)) after BR was greater in the endurance athletes than in the remaining groups (17 vs. 10%). Decrements in VO(2 peak) correlated positively with the initial values (r = 0.73, P < 0.001). Resting and exercise respiratory exchange ratios were increased in athletes. Cardiac output was unchanged by BR in all groups, but exercise HR was increased and SV diminished in the sedentary subjects. The submaximal [LA] and [LA] thresholds were decreased in the endurance athletes from 71 to 60% VO(2 peak) (P < 0.001); they also had an earlier increase in [NE], an attenuated increase in [hGH], and accentuated PRA and cortisol elevations during exercise. These effects were insignificant in the remaining subjects. In conclusion, reduction of exercise performance and modifications in neurohormonal response to exercise after BR depend on the previous level and mode of physical training, being the most pronounced in the endurance athletes.

Steady and dynamic shear rheological behavior of semi dilute Alyssum homolocarpum seed gum solutions: influence of concentration, temperature and heating-cooling rate.

PubMed

Alaeddini, Behzad; Koocheki, Arash; Mohammadzadeh Milani, Jafar; Razavi, Seyed Mohammad Ali; Ghanbarzadeh, Babak

2018-05-01

Alyssum homolocarpum seed gum (AHSG) solution exhibits high viscosity at low shear rates and has anionic features. However there is no information regarding the flow and dynamic properties of this gum in semi-dilute solutions. The present study aimed to investigate the dynamic and steady shear behavior of AHSG in the semi-dilute region. The viscosity profile demonestrated a shear thinning behavior at all temperatures and concentrations. An increase in the AHSG concentration was acompanied by an increase in the pseudoplasticity degree, whereas, by increasing the temperature, the pseudoplasticity of AHSG decreased. At low gum concentration, solutions had more viscosity dependence on temperature. The mechanical spectra obtained from the frequency sweep experiment demonstrated viscoelastic properties for gum solutions. AHSG solutions showed typical weak gel-like behavior, revealing G' greater than G' within the experimental range of frequency (Hz), with slight frequency dependency. The influence of temperature on viscoelastic properties of AHSG solutions was studied during both heating (5-85 °C) and cooling (85-5 °C) processes. The complex viscosity of AHSG was greater compared to the apparent viscosity, indicating the disruption of AHSG network structure under continuous shear rates and deviation from the Cox-Merz rule. During the initial heating, the storage modulus showed a decreasing trend and, with a further increase in temperature, the magnitude of storage modulus increased. The influence of temperature on the storage modulus was considerable when a higher heating rate was applied. AHSG can be applied as a thickening and stabilizing agents in food products that require good stability against temperature. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Stimulation of mucosal secretion by lubiprostone (SPI-0211) in guinea pig small intestine and colon

PubMed Central

Fei, Guijun; Wang, Yu-Zhong; Liu, Sumei; Hu, Hong-Zhen; Wang, Guo-Du; Qu, Mei-Hua; Wang, Xi-Yu; Xia, Yun; Sun, Xiaohong; Bohn, Laura M.; Cooke, Helen J.; Wood, Jackie D.

2009-01-01

Actions of lubiprostone, a selective type-2 chloride channel activator, on mucosal secretion were investigated in guinea pig small intestine and colon. Flat-sheet preparations were mounted in Ussing flux chambers for recording short-circuit current (Isc) as a marker for electrogenic chloride secretion. Lubiprostone, applied to the small intestinal mucosa in eight concentrations ranging from 1–3000 nM, evoked increases in Isc in a concentration-dependent manner with an EC50 of 42.5 nM. Lubiprostone applied to the mucosa of the colon in eight concentrations ranging from 1–3000 nM evoked increases in Isc in a concentration-dependent manner with an EC50 of 31.7 nM. Blockade of enteric nerves by tetrodotoxin did not influence stimulation of Isc by lubiprostone. Antagonists acting at prostaglandin (PG)E2, EP1–3, or EP4 receptors did not suppress stimulation of Isc by lubiprostone but suppressed or abolished PGE2-evoked responses. Substitution of gluconate for chloride abolished all responses to lubiprostone. The selective CFTR channel blocker, CFTR(inh)-172, did not suppress lubiprostone-evoked Isc. The broadly acting blocker, glibenclamide, suppressed (P < 0.001) lubiprostone-evoked Isc. Lubiprostone, in the presence of tetrodotoxin, enhanced carbachol-evoked Isc. The cholinergic component, but not the putative vasoactive intestinal peptide component, of neural responses to electrical field stimulation was enhanced by lubiprostone. Application of any of the prostaglandins, E2, F2, or I2, evoked depolarization of the resting membrane potential in enteric neurons. Unlike the prostaglandins, lubiprostone did not alter the electrical behavior of enteric neurons. Exposure to the histamine H2 receptor agonists increased basal Isc followed by persistent cyclical increases in Isc. Lubiprostone increased the peak amplitude of the dimaprit-evoked cycles. PMID:19179625

Stimulation of mucosal secretion by lubiprostone (SPI-0211) in guinea pig small intestine and colon.

PubMed

Fei, Guijun; Wang, Yu-Zhong; Liu, Sumei; Hu, Hong-Zhen; Wang, Guo-Du; Qu, Mei-Hua; Wang, Xi-Yu; Xia, Yun; Sun, Xiaohong; Bohn, Laura M; Cooke, Helen J; Wood, Jackie D

2009-04-01

Actions of lubiprostone, a selective type-2 chloride channel activator, on mucosal secretion were investigated in guinea pig small intestine and colon. Flat-sheet preparations were mounted in Ussing flux chambers for recording short-circuit current (Isc) as a marker for electrogenic chloride secretion. Lubiprostone, applied to the small intestinal mucosa in eight concentrations ranging from 1-3000 nM, evoked increases in Isc in a concentration-dependent manner with an EC50 of 42.5 nM. Lubiprostone applied to the mucosa of the colon in eight concentrations ranging from 1-3000 nM evoked increases in Isc in a concentration-dependent manner with an EC50 of 31.7 nM. Blockade of enteric nerves by tetrodotoxin did not influence stimulation of Isc by lubiprostone. Antagonists acting at prostaglandin (PG)E2, EP1-3, or EP4 receptors did not suppress stimulation of Isc by lubiprostone but suppressed or abolished PGE2-evoked responses. Substitution of gluconate for chloride abolished all responses to lubiprostone. The selective CFTR channel blocker, CFTR(inh)-172, did not suppress lubiprostone-evoked Isc. The broadly acting blocker, glibenclamide, suppressed (P<0.001) lubiprostone-evoked Isc. Lubiprostone, in the presence of tetrodotoxin, enhanced carbachol-evoked Isc. The cholinergic component, but not the putative vasoactive intestinal peptide component, of neural responses to electrical field stimulation was enhanced by lubiprostone. Application of any of the prostaglandins, E2, F2, or I2, evoked depolarization of the resting membrane potential in enteric neurons. Unlike the prostaglandins, lubiprostone did not alter the electrical behavior of enteric neurons. Exposure to the histamine H2 receptor agonists increased basal Isc followed by persistent cyclical increases in Isc. Lubiprostone increased the peak amplitude of the dimaprit-evoked cycles.

Dual role of betel leaf extract on thyroid function in male mice.

PubMed

Panda, S; Kar, A

1998-12-01

The effects of betel leaf extract (0.10, 0.40, 0.80 and 2.0 g kg-1 day-1 for 15 days) on the alterations in thyroid hormone concentrations. lipid peroxidation (LPO) and on the activities of superoxide dismutase (SOD) and catalase (CAT) were investigated in male Swiss mice. Administration of betel leaf extract exhibited a dual role, depending on the different doses. While the lowest dose decreased thyroxine (T4) and increased serum triiodothyronine (T3) concentrations, reverse effects were observed at two higher doses. Higher doses also increased LPO with a concomitant decrease in SOD and CAT activities. However, with the lowest dose most of these effects were reversed. These findings suggest that betel leaf can be both stimulatory and inhibitory to thyroid function, particularly for T3 generation and lipid peroxidation in male mice, depending on the amount consumed.

Simple size-controlled synthesis of Au nanoparticles and their size-dependent catalytic activity

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

Suchomel, Petr; Kvitek, Libor; Prucek, Robert

The controlled preparation of Au nanoparticles (NPs) in the size range of 6 to 22 nm is explored in this study. The Au NPs were prepared by the reduction of tetrachloroauric acid using maltose in the presence of nonionic surfactant Tween 80 at various concentrations to control the size of the resulting Au NPs. With increasing concentration of Tween 80 a decrease in the size of produced Au NPs was observed, along with a significant decrease in their size distribution. The size-dependent catalytic activity of the synthesized Au NPs was tested in the reduction of 4-nitrophenol with sodium borohydride, resultingmore » in increasing catalytic activity with decreasing size of the prepared nanoparticles. Eley-Rideal catalytic mechanism emerges as the more probable, in contrary to the Langmuir-Hinshelwood mechanism reported for other noble metal nanocatalysts.« less

Simple size-controlled synthesis of Au nanoparticles and their size-dependent catalytic activity

DOE PAGES

Suchomel, Petr; Kvitek, Libor; Prucek, Robert; ...

2018-03-15

The controlled preparation of Au nanoparticles (NPs) in the size range of 6 to 22 nm is explored in this study. The Au NPs were prepared by the reduction of tetrachloroauric acid using maltose in the presence of nonionic surfactant Tween 80 at various concentrations to control the size of the resulting Au NPs. With increasing concentration of Tween 80 a decrease in the size of produced Au NPs was observed, along with a significant decrease in their size distribution. The size-dependent catalytic activity of the synthesized Au NPs was tested in the reduction of 4-nitrophenol with sodium borohydride, resultingmore » in increasing catalytic activity with decreasing size of the prepared nanoparticles. Eley-Rideal catalytic mechanism emerges as the more probable, in contrary to the Langmuir-Hinshelwood mechanism reported for other noble metal nanocatalysts.« less

Effects of papaverine on carbachol- and high K+ -induced contraction in the bovine abomasum.

PubMed

Kaneda, Takeharu; Saito, Erika; Kanda, Hidenori; Urakawa, Norimoto; Shimizu, Kazumasa

2015-10-01

The effects of papaverine on carbachol (CCh) -and high K(+)- induced contraction in the bovine abomasum were investigated. Papaverine inhibited CCh (1 µM) -and KCl (65 mM) -induced contractions in a concentration-dependent manner. Forskolin or sodium nitroprusside inhibited CCh-induced contractions in a concentration-dependent manner in association with increases in the cAMP or cGMP contents, whereas papaverine increased cGMP contents only at 30 µM. Changes in the extracellular Ca(2+) from 1.5 mM to 7.5 mM reduced verapamil-induced relaxation in high K(+)-depolarized muscles, but papaverine-induced relaxation did not change. Furthermore, papaverine (30 µM) and NaCN (300 µM) decreased the creatine phosphate contents. These results suggest that the relaxing effects of papaverine on the bovine abomasum are mainly due to the inhibition of aerobic energy metabolism.

Methylmercury Exposure Induces Sexual Dysfunction in Male and Female Drosophila Melanogaster.

PubMed

Chauhan, Ved; Srikumar, Syian; Aamer, Sarah; Pandareesh, Mirazkar D; Chauhan, Abha

2017-09-24

Mercury, an environmental health hazard, is a neurotoxic heavy metal. In this study, the effect of methylmercury (MeHg) exposure was analyzed on sexual behavior in Drosophila melanogaster (fruit fly), because neurons play a vital role in sexual functions. The virgin male and female flies were fed a diet mixed with different concentrations of MeHg (28.25, 56.5, 113, 226, and 339 µM) for four days, and the effect of MeHg on copulation of these flies was studied. While male and female control flies (no MeHg) and flies fed with lower concentrations of MeHg (28.25, 56.5 µM) copulated in a normal manner, male and female flies exposed to higher concentrations of MeHg (113, 226, and 339 µM) did not copulate. When male flies exposed to higher concentrations of MeHg were allowed to copulate with control female flies, only male flies fed with 113 µM MeHg were able to copulate. On the other hand, when female flies exposed to higher concentrations of MeHg were allowed to copulate with control male flies, none of the flies could copulate. After introduction of male and female flies in the copulation chamber, duration of wing flapping by male flies decreased in a MeHg-concentration-dependent manner from 101 ± 24 seconds (control) to 100.7 ± 18, 96 ±12, 59 ± 44, 31 ± 15, and 3.7 ± 2.7 seconds at 28.25, 56.5, 113, 226, and 339 µM MeHg, respectively. On the other hand, grooming in male and female flies increased in a MeHg-concentration-dependent manner. These findings suggest that MeHg exposure causes sexual dysfunction in male and female Drosophila melanogaster . Further studies showed that MeHg exposure increased oxidative stress and decreased triglyceride levels in a concentration-dependent manner in both male and female flies, suggesting that MeHg-induced oxidative stress and decreased triglyceride levels may partly contribute to sexual dysfunction in fruit flies.

Water diffusion in silicate glasses: the effect of glass structure

NASA Astrophysics Data System (ADS)

Kuroda, M.; Tachibana, S.

2016-12-01

Water diffusion in silicate melts (glasses) is one of the main controlling factors of magmatism in a volcanic system. Water diffusivity in silicate glasses depends on its own concentration. However, the mechanism causing those dependences has not been fully understood yet. In order to construct a general model for water diffusion in various silicate glasses, we performed water diffusion experiments in silica glass and proposed a new water diffusion model [Kuroda et al., 2015]. In the model, water diffusivity is controlled by the concentration of both main diffusion species (i.e. molecular water) and diffusion pathways, which are determined by the concentrations of hydroxyl groups and network modifier cations. The model well explains the water diffusivity in various silicate glasses from silica glass to basalt glass. However, pre-exponential factors of water diffusivity in various glasses show five orders of magnitude variations although the pre-exponential factor should ideally represent the jump frequency and the jump distance of molecular water and show a much smaller variation. Here, we attribute the large variation of pre-exponential factors to a glass structure dependence of activation energy for molecular water diffusion. It has been known that the activation energy depends on the water concentration [Nowak and Behrens, 1997]. The concentration of hydroxyls, which cut Si-O-Si network in the glass structure, increases with water concentration, resulting in lowering the activation energy for water diffusion probably due to more fragmented structure. Network modifier cations are likely to play the same role as water. With taking the effect of glass structure into account, we found that the variation of pre-exponential factors of water diffusivity in silicate glasses can be much smaller than the five orders of magnitude, implying that the diffusion of molecular water in silicate glasses is controlled by the same atomic process.

Anisotropy of the neutron fluence from a plasma focus.

NASA Technical Reports Server (NTRS)

Lee, J. H.; Shomo, L. P.; Kim, K. H.

1972-01-01

The fluence of neutrons from a plasma focus was measured by gamma spectrometry of an activated silver target. This method results in a significant increase in accuracy over the beta-counting method. Multiple detectors were used in order to measure the anisotropy of the fluence of neutrons. The fluence was found to be concentrated in a cone with a half-angle of 30 deg about the axis, and to drop off rapidly outside of this cone; the anisotropy was found to depend upon the total yield of neutrons. This dependence was strongest on the axis. Neither the axial concentration of the fluence of neutrons nor its dependence on the total yield of neutrons is explained by any of the currently proposed models. Some other explanations, including the possibility of an axially distributed source, are considered.

Hydrotropic Solubilization of Lipophilic Drugs for Oral Delivery: The Effects of Urea and Nicotinamide on Carbamazepine Solubility–Permeability Interplay

PubMed Central

Beig, Avital; Lindley, David; Miller, Jonathan M.; Agbaria, Riad; Dahan, Arik

2016-01-01

Hydrotropy refers to increasing the water solubility of otherwise poorly soluble compound by the presence of small organic molecules. While it can certainly increase the apparent solubility of a lipophilic drug, the effect of hydrotropy on the drugs’ permeation through the intestinal membrane has not been studied. The purpose of this work was to investigate the solubility–permeability interplay when using hydrotropic drug solubilization. The concentration-dependent effects of the commonly used hydrotropes urea and nicotinamide, on the solubility and the permeability of the lipophilic antiepileptic drug carbamazepine were studied. Then, the solubility–permeability interplay was mathematically modeled, and was compared to the experimental data. Both hydrotropes allowed significant concentration-dependent carbamazepine solubility increase (up to ∼30-fold). A concomitant permeability decrease was evident both in vitro and in vivo (∼17-fold for nicotinamide and ∼9-fold for urea), revealing a solubility–permeability tradeoff when using hydrotropic drug solubilization. A relatively simplified simulation approach based on proportional opposite correlation between the solubility increase and the permeability decrease at a given hydrotrope concentration allowed excellent prediction of the overall solubility–permeability tradeoff. In conclusion, when using hydrotropic drug solubilization it is prudent to not focus solely on solubility, but to account for the permeability as well; achieving optimal solubility–permeability balance may promote the overall goal of the formulation to maximize oral drug exposure. PMID:27826241

Cytotoxic effects of Urtica dioica radix on human colon (HT29) and gastric (MKN45) cancer cells mediated through oxidative and apoptotic mechanisms.

PubMed

Ghasemi, S; Moradzadeh, M; Mousavi, S H; Sadeghnia, H R

2016-10-15

Defects in the apoptotic pathways are responsible for both the colorectal cancer pathogenesis and resistance to therapy. In this study, we examined the level of cellular oxidants, cytotoxicity and apoptosis induced by hydroalcoholic extract of U. dioica radix (0-2000 µg/mL) and oxaliplatin (0-1000 µg/mL, as positive control) in human gastric (MKN45) and colon (HT29) cancer, as well as normal human foreskin fibroblast (HFF) cells. Exposure to U. dioica or oxaliplatin showed a concentration dependent suppression in cell survival with IC50 values of 24.7, 249.9 and 857.5 µg/mL for HT29, MKN45 and HFF cells after 72 h treatment, respectively. ROS formation and lipid peroxidation were also concentration-dependently increased following treatment with U. dioica, similar to oxaliplatin. In addition, the number of apoptotic cells significantly increased concomitantly with concentration of U. dioica as compared with control cells, which is similar to oxaliplatin and serum-deprived cancer cells. In conclusion, the present study demonstrated that U. dioica inhibited proliferation of gastric and colorectal cancer cells while posing no significant toxic effect on normal cells. U. dioica not only increased levels of oxidants, but also induced concomitant increase of apoptosis. The precise signaling pathway by which U. dioica induce apoptosis needs further research.

Continuous and Delayed Photohemolysis Sensitized With Methylene Blue and Iron Oxide Nanoparticles (Fe3O4)

NASA Astrophysics Data System (ADS)

AL-Akhras, M.-Ali; Aljarrah, Khaled; Albiss, Borhan; Alhaji Bala, Abba

2015-10-01

This research present the sensitization of methylene blue (MB), as a potential photodynamic therapy photo sensitizer which showed phototoxicity for many tumor cells in vitro incorporated with iron oxide nanoparticles (Fe3O4, IO-NP), which offer magnificent interaction both inside and outside the surface of biomolecules together with red blood cells (RBC's) with significant change in hemolysis process. The study investigated the sensitization of continuous photohemolysis (CPH) for MB and MB with IO-NP, delayed photohemolysis (DPH) at different irradiation temperature (Tirr). The photohemolysis rate for CPH at room temperature has a power dependence of 0.39 ± 0.05 with relative of steepness of 1.25 ± 0.02 and for different concentration of MB and power dependent of 0.15 ± 0.03 with relative steepness of 1.34 ± 0.01 for different MB and IO-NP. Logistic and Gompertz functions were applied as appropriate mathematical models to fit the collected experimental data for CPH and DPH respectively, and to calculate fractional photohemolysis rate with minimum errors. The Logistic function parameter; α, the hemolysis rate, increases with increasing concentrations of MB and decreases with increasing IO-NP concentrations in the presence of 6 μg/ml of MB. The parameter β the time required to reduce the maximum number of RBCs to one half of its value, decreases with increasing MB concentration and increases with increasing IO-NP concentrations in the presence of 6 pg/ml of MB. In DPH at different Tirr, the Gompertz parameter; a, fractional hemolysis ratio, is independent of temperature in both case MB and MB plus IO-NP, while the parameter; b, rate of fractional hemolysis change, increases with increasing Tirr, in both case MB and MB plus IO-NP. The apparent activation energy of colloid-osmotic hemolysis is 9.47±0.01 Kcal/mol with relative steepness of 1.31 ± 0.05 for different MB and 6.06±0.03 Kcal/mol with relative steepness of 1.41 ± 0.09 for MB with iron oxide. Our results suggest that Logistic equation is the best fit for the CPH and Gompertz function for the DPH. Both models predict also that the relative steepness is independent of the light dose, sensitizer and IO-NP concentrations.

Age-dependent accumulation of heavy metals in a pod of killer whales (Orcinus orca) stranded in the northern area of Japan.

PubMed

Endo, Tetsuya; Kimura, Osamu; Hisamichi, Yohsuke; Minoshima, Yasuhiko; Haraguchi, Koichi

2007-02-01

Mercury (Hg), cadmium (Cd), iron (Fe) manganese (Mn), zinc (Zn) and copper (Cu) concentrations in the liver, kidney and muscle of nine killer whales (including three calves) that stranded together in the northern area of Japan were determined. The Hg and Cd concentrations were found at trace levels in the calf organs, and increased with age. The Fe concentration in the muscle was significantly lower in the calves than in the mature whales and also increased with age. In contrast, Mn and Cu concentrations in the muscle were significantly higher in the calves than in the mature whales, and changes in the Zn concentration relative to age were unclear. These results suggest minimal mother-to-calf transfer of the toxic metals Hg and Cd and accumulation of these metals in the organs with age, while the essential metals Mn and Cu were found at higher concentrations in the muscle of calves than in mature whales.

Indoor birch pollen concentrations differ with ventilation scheme, room location, and meteorological factors.

PubMed

Menzel, A; Matiu, M; Michaelis, R; Jochner, S

2017-05-01

Indoor pollen concentrations are an underestimated human health issue. In this study, we measured hourly indoor birch pollen concentrations on 8 days in April 2015 with portable pollen traps in five rooms of a university building at Freising, Germany. These data were compared to the respective outdoor values right in front of the rooms and to background pollen data. The rooms were characterized by different aspects and window ventilation schemes. Meteorological data were equally measured directly in front of the windows. Outdoor concentration could be partly explained with phenological data of 56 birches in the surrounding showing concurrent high numbers of trees attaining flowering stages. Indoor pollen concentrations were lower than outdoor concentrations: mean indoor/outdoor (I/O) ratio was highest in a room with fully opened window and additional mechanical ventilation (.75), followed by rooms with fully opened windows (.35, .12) and lowest in neighboring rooms with tilted window (.19) or windows only opened for short ventilation (.07). Hourly I/O ratios depended on meteorology and increased with outside temperature and wind speed oriented perpendicular to the window opening. Indoor concentrations additionally depended on the previously measured concentrations, indicating accumulation of pollen inside the rooms even after the full flowering period. © 2016 The Authors. Indoor Air Published by John Wiley & Sons Ltd.

Concentration-Dependent Patterns of Leucine Incorporation by Coastal Picoplankton

PubMed Central

Alonso, Cecilia; Pernthaler, Jakob

2006-01-01

Coastal pelagic environments are believed to feature concentration gradients of dissolved organic carbon at a microscale, and they are characterized by pronounced seasonal differences in substrate availability for the heterotrophic picoplankton. Microbial taxa that coexist in such habitats might thus differ in their ability to incorporate substrates at various concentrations. We investigated the incorporation patterns of leucine in four microbial lineages from the coastal North Sea at concentrations between 0.1 and 100 nM before and during a spring phytoplankton bloom. Community bulk incorporation rates and the fraction of leucine-incorporating cells in the different populations were analyzed. Significantly fewer bacterial cells incorporated the amino acid before (13 to 35%) than during (23 to 47%) the bloom at all but the highest concentration. The incorporation rate per active cell in the prebloom situation was constant above 0.1 nM added leucine, whereas it increased steeply with substrate concentration during the bloom. At both time points, a high proportion of members of the Roseobacter clade incorporated leucine at all concentrations (55 to 80% and 86 to 94%, respectively). In contrast, the fractions of leucine-incorporating cells increased substantially with substrate availability in bacteria from the SAR86 clade (8 to 31%) and from DE cluster 2 of the Flavobacteria-Sphingobacteria (14 to 33%). The incorporation patterns of marine Euryarchaeota were between these extremes (30 to 56% and 48 to 70%, respectively). Our results suggest that the contribution of microbial taxa to the turnover of particular substrates may be concentration dependent. This may help us to understand the specific niches of coexisting populations that appear to compete for the same resources. PMID:16517664

pH effects on the hyaluronan hydrolysis catalysed by hyaluronidase in the presence of proteins: Part I. Dual aspect of the pH-dependence.

PubMed

Lenormand, Hélène; Deschrevel, Brigitte; Vincent, Jean-Claude

2010-05-01

Hyaluronan (HA) hydrolysis catalysed by hyaluronidase (HAase) is strongly inhibited when performed at a low ratio of HAase to HA concentrations and at low ionic strength. This is because long HA chains can form non-active complexes with HAase. Bovine serum albumin (BSA) is able to compete with HAase to form electrostatic complexes with HA so freeing HAase which then recovers its catalytic activity. This BSA-dependence is characterised by two main domains separated by the optimal BSA concentration: below this concentration the HAase activity increases when the BSA concentration is increased, above this concentration the HAase activity decreases. This occurs provided that HA is negatively charged and BSA is positively charged, i.e. in a pH range from 3 to 5.25. The higher the pH value the higher the optimal BSA concentration. Other proteins can also modulate HAase activity. Lysozyme, which has a pI higher than that of BSA, is also able to compete with HAase to form electrostatic complexes with HA and liberate HAase. This occurs over a wider pH range that extends from 3 to 9. These results mean that HAase can form complexes with HA and recover its enzymatic activity at pH as high as 9, consistent with HAase having either a high pI value or positively charged patches on its surface at high pH. Finally, the pH-dependence of HAase activity, which results from the influence of pH on both the intrinsic HAase activity and the formation of complexes between HAase and HA, shows a maximum at pH 4 and a significant activity up to pH 9. Copyright 2009 International Society of Matrix Biology. Published by Elsevier B.V. All rights reserved.

Solar concentration properties of flat fresnel lenses with large F-numbers

NASA Technical Reports Server (NTRS)

Cosby, R. M.

1978-01-01

The solar concentration performances of flat, line-focusing sun-tracking Fresnel lenses with selected f-numbers between 0.9 and 2.0 were analyzed. Lens transmittance was found to have a weak dependence on f-number, with a 2% increase occuring as the f-number is increased from 0.9 to 2.0. The geometric concentration ratio for perfectly tracking lenses peaked for an f-number near 1.35. Intensity profiles were more uniform over the image extent for large f-number lenses when compared to the f/0.9 lens results. Substantial decreases in geometri concentration ratios were observed for transverse tracking errors equal to or below 1 degree for all f-number lenses. With respect to tracking errors, the solar performance is optimum for f-numbers between 1.25 and 1.5.

Energetic aspects of the light activation of two chloroplast enzymes: fructose-1,6-bisphosphatase and NADP-malate dehydrogenase.

PubMed

Miginiac-Maslow, M; Jacquot, J P; Droux, M

1985-09-01

The light energy requirements for photoactivation of two chloroplast enzymes: fructose-1,6-bisphosphatase and NADP-malate dehydrogenase were studied in a reconstituted chloroplast system. This system comprised isolated pea thylakoids, ferredoxin (Fd), ferredoxin-thioredoxin reductase (FTR) thioredoxinm and f (Tdm, Tdf) and the photoactivatable enzyme. Light-saturation curves of the photoactivation process were established with once washed thylakoids which did not require the addition of Td for light activation. They exhibited a plateau at 10 W·m(-2) under nitrogen and 50 W·m(-2) under air, while NADP photoreduction was saturated at 240 W·m(-2). Cyclic and pseudocyclic phosphorylations saturated at identical levels as enzyme photoactivations. All these observations suggested that the shift of the light saturation plateau towards higher values under air was due to competing oxygen-dependent reactions. With twice washed thylakoids, which required Td for enzyme light-activation, photophosphorylation was stimulated under N2 by the addition of the components of the photoactivation system. Its rate increased with increasing Td concentrations, just as did the enzyme photoactivation rate, while varying the target enzyme concentration had only a weak effect. Considering that Td concentrations were in a large excess over target enzyme concentrations, it may be assumed that the observed ATP synthesis was essentially dependent on the rate of Td reduction.Under air, Fd-dependent pseudo-cyclic photophosphorylation was not stimulated by the addition of the other enzyme photoactivation components, suggesting that an important site of action of O2 was located at the level of Fd.

cDNA cloning and functional characterization of the mouse Ca2+-gated K+ channel, mIK1. Roles in regulatory volume decrease and erythroid differentiation.

PubMed

Vandorpe, D H; Shmukler, B E; Jiang, L; Lim, B; Maylie, J; Adelman, J P; de Franceschi, L; Cappellini, M D; Brugnara, C; Alper, S L

1998-08-21

We have cloned from murine erythroleukemia (MEL) cells, thymus, and stomach the cDNA encoding the Ca2+-gated K+ (KCa) channel, mIK1, the mouse homolog of hIK1 (Ishii, T. M., Silvia, C., Hirschberg, B., Bond, C. T., Adelman, J. P., and Maylie, J. (1997) Proc. Natl. Acad. Sci.(U. S. A. 94, 11651-11656). mIK1 mRNA was detected at varied levels in many tissue types. mIK1 KCa channel activity expressed in Xenopus oocytes closely resembled the Kca of red cells (Gardos channel) and MEL cells in its single channel conductance, lack of voltage-sensitivity of activation, inward rectification, and Ca2+ concentration dependence. mIK1 also resembled the erythroid channel in its pharmacological properties, mediating whole cell and unitary currents sensitive to low nM concentrations of both clotrimazole (CLT) and its des-imidazolyl metabolite, 2-chlorophenyl-bisphenyl-methanol, and to low nM concentrations of iodocharybdotoxin. Whereas control oocytes subjected to hypotonic swelling remained swollen, mIK1 expression conferred on oocytes a novel, Ca2+-dependent, CLT-sensitive regulatory volume decrease response. Hypotonic swelling of voltage-clamped mIK1-expressing oocytes increased outward currents that were Ca2+-dependent, CLT-sensitive, and reversed near the K+ equilibrium potential. mIK1 mRNA levels in ES cells increased steadily during erythroid differentiation in culture, in contrast to other KCa mRNAs examined. Low nanomolar concentrations of CLT inhibited proliferation and erythroid differentiation of peripheral blood stem cells in liquid culture.

Energy Independence: Caught Behind the Power Curve

DTIC Science & Technology

2010-04-01

further compound the issue of increased oil consumption, the global oil reserves are finite and diminishing. The production or yield of an oil...amount of solar radiation reaching the surface of the earth is also dependent on the inclination of the earth and the latitude of the collectors . The...uses parabolic mirrors to direct and concentrate the solar radiation. This concentrated radiation is then used to create steam which drives a steam

Electrical and structural properties of In-implanted Si 1–xGe x alloys

DOE PAGES

Feng, Ruixing; Kremer, F.; Sprouster, D. J.; ...

2016-01-14

Here, we report on the effects of dopant concentration and substrate stoichiometry on the electrical and structural properties of In-implanted Si 1–xGe x alloys. Correlating the fraction of electrically active In atoms from Hall Effect measurements with the In atomic environment determined by X-ray absorption spectroscopy, we observed the transition from electrically active, substitutional In at low In concentration to electrically inactive metallic In at high In concentration. The In solid-solubility limit has been quantified and was dependent on the Si 1–xGe x alloy stoichiometry; the solid-solubility limit increased as the Ge fraction increased. This result was consistent with densitymore » functional theory calculations of two In atoms in a Si 1–xGe x supercell that demonstrated that In–In pairing was energetically favorable for x ≲ 0.7 and energetically unfavorable for x ≳ 0.7. Transmission electron microscopy imaging further complemented the results described earlier with the In concentration and Si 1–xGe x alloy stoichiometry dependencies readily visible. We have demonstrated that low resistivity values can be achieved with In implantation in Si 1–xGe x alloys, and this combination of dopant and substrate represents an effective doping protocol.« less

WITHAFERIN A INDUCES APOPTOSIS IN RAT C6 GLIOMA CELLS THROUGH REGULATING NF-KB NUCLEAR TRANSLOCATION AND ACTIVATION OF CASPASE CASCADE.

PubMed

Hou, Wei-Chen; Miao, Xiao-Hui; Ma, Lian-Jun; Bai, Xiao-Xue; Liu, Qun; Song, Lei

2017-01-01

The demand for the chemopreventive drug from the plant source is increasing in recent times, owing to its various biological activities without any adverse effect. The intention of this current study was to examine the anti-glioma effect of Withaferin A (WFA) on C6 glioma cell line model. C6 glioma cells were administrated with different concentration of WFA (50, 100, 200 and 500 μg/mL) and DMSO (control) group to examine its anti-proliferative, anti-inflammatory and pro-apoptotic activities. Treatment with WFA showed a significant decline in the glioma cell count in a dose-dependent manner and thus proving its anti-proliferative effect. Similarly, inflammatory markers were also substantially lowered upon treatment with different concentration of WFA. However, DNA fragmentation and apoptotic markers like Caspase-3 and 9 were concomitantly enhanced after co-cultured with different concentration of WFA and thus exhibiting its cytotoxicity efficacy. Furthermore, the protein expression of Bcl2 and Bax were markedly downregulated and upregulated respectively; upon treatment with WFA on C6 glioma cells. The outcome of this study evidently demonstrates that C6 glioma cells co-cultured with increased concentration of WFA, showed an anti-proliferative, anti-inflammatory and pro-apoptotic effect in a dose-dependent fashion.

Periodic Colony Formation by Bacterial Species Bacillus subtilis

NASA Astrophysics Data System (ADS)

Wakita, Jun-ichi; Shimada, Hirotoshi; Itoh, Hiroto; Matsuyama, Tohey; Matsushita, Mitsugu

2001-03-01

We have investigated the periodic colony growth of bacterial species Bacillus subtilis. A colony grows cyclically with the interface repeating an advance (migration phase) and a rest (consolidation phase) alternately on a surface of semi-solid agar plate under appropriate environmental conditions, resulting in a concentric ring-like colony. It was found from macroscopic observations that the characteristic quantities for the periodic growth such as the migration time, the consolidation time and the terrace spacing do not depend so much on nutrient concentration Cn, but do on agar concentration Ca. The consolidation time was a weakly increasing function of Ca, while the migration time and the terrace spacing were, respectively, weakly and strongly decreasing function of Ca. Overall, the cycle (migration-plus-consolidation) time seems to be constant, and does not depend so much on both Cn and Ca. Microscopically, bacterial cells inside the growing front of a colony keep increasing their population during both migration and consolidation phases. It was also confirmed that their secreting surfactant called surfactin does not affect their periodic growth qualitatively, i.e., mutant cells which cannot secrete surfactin produce a concentric ring-like colony. All these results suggest that the diffusion of the nutrient and the surfactin are irrelevant to their periodic growth.

Cation-induced transcriptional regulation of the dlt operon of Staphylococcus aureus.

PubMed

Koprivnjak, Tomaz; Mlakar, Vid; Swanson, Lindsey; Fournier, Benedicte; Peschel, Andreas; Weiss, Jerrold P

2006-05-01

Lipoteichoic and wall teichoic acids (TA) are highly anionic cell envelope-associated polymers containing repeating polyglycerol/ribitol phosphate moieties. Substitution of TA with D-alanine is important for modulation of many cell envelope-dependent processes, such as activity of autolytic enzymes, binding of divalent cations, and susceptibility to innate host defenses. D-Alanylation of TA is diminished when bacteria are grown in medium containing increased NaCl concentrations, but the effects of increased salt concentration on expression of the dlt operon encoding proteins mediating D-alanylation of TA are unknown. We demonstrate that Staphylococcus aureus transcriptionally represses dlt expression in response to high concentrations of Na(+) and moderate concentrations of Mg(2+) and Ca(2+) but not sucrose. Changes in dlt mRNA are induced within 15 min and sustained for several generations of growth. Mg(2+)-induced dlt repression depends on the ArlSR two-component system. Northern blotting, reverse transcription-PCR, and SMART-RACE analyses suggest that the dlt transcript begins 250 bp upstream of the dltA start codon and includes an open reading frame immediately upstream of dltA. Chloramphenicol transacetylase transcriptional fusions indicate that a region encompassing the 171 to 325 bp upstream of dltA is required for expression and Mg(2+)-induced repression of the dlt operon in S. aureus.

Cation-Induced Transcriptional Regulation of the dlt Operon of Staphylococcus aureus

PubMed Central

Koprivnjak, Tomaz; Mlakar, Vid; Swanson, Lindsey; Fournier, Benedicte; Peschel, Andreas; Weiss, Jerrold P.

2006-01-01

Lipoteichoic and wall teichoic acids (TA) are highly anionic cell envelope-associated polymers containing repeating polyglycerol/ribitol phosphate moieties. Substitution of TA with d-alanine is important for modulation of many cell envelope-dependent processes, such as activity of autolytic enzymes, binding of divalent cations, and susceptibility to innate host defenses. d-Alanylation of TA is diminished when bacteria are grown in medium containing increased NaCl concentrations, but the effects of increased salt concentration on expression of the dlt operon encoding proteins mediating d-alanylation of TA are unknown. We demonstrate that Staphylococcus aureus transcriptionally represses dlt expression in response to high concentrations of Na+ and moderate concentrations of Mg2+ and Ca2+ but not sucrose. Changes in dlt mRNA are induced within 15 min and sustained for several generations of growth. Mg2+-induced dlt repression depends on the ArlSR two-component system. Northern blotting, reverse transcription-PCR, and SMART-RACE analyses suggest that the dlt transcript begins 250 bp upstream of the dltA start codon and includes an open reading frame immediately upstream of dltA. Chloramphenicol transacetylase transcriptional fusions indicate that a region encompassing the 171 to 325 bp upstream of dltA is required for expression and Mg2+-induced repression of the dlt operon in S. aureus. PMID:16672616

The pH dependence of silicon-iron interaction in rats.

PubMed

Jia, X; Emerick, R J; Kayongo-Male, H

1997-01-01

A 2 x 2 x 3 factorial experiment was conducted to study the pH dependence of a silicon-iron interaction in vivo. The dietary treatments used in the factorial design were the following (mg/kg of diet): silicon, 0 and 500; iron, 35 and 187; acid-base, ammonium chloride as 0.5% of total diet (acidic), sodium bicarbonate as 1.0% of total diet (basic), or no supplementation of acid or base (control). The supplementation of 500 mg silicon/kg of diet increased plasma-iron concentration in rats fed the acidic or control diets, but not in rats fed the basic diet. A high dietary-iron level suppressed copper absorption and utilization and subsequently imposed a negative effect on its own utilization. An increase in the plasma total-cholesterol concentration caused by high dietary-iron level was likely a consequence of the antagonistic effect of iron on copper absorption and utilization. The use of cupric sulfate pentahydrate as the dietary-copper source in this study resulted in plasma copper concentrations that were approximately twice those obtained in a related study using cupric carbonate. Also, a 42% coefficient of variation (C.V.) for plasma-copper concentrations of rats fed cupric sulfate in this study was greatly reduced from the C.V. = 108% previously associated with the dietary cupric carbonate.

Genotoxic effects of boric acid and borax in zebrafish, Danio rerio using alkaline comet assay

PubMed Central

Gülsoy, Nagihan; Yavas, Cüneyd; Mutlu, Özal

2015-01-01

The present study is conducted to determine the potential mechanisms of Boron compounds, boric acid (BA) and borax (BX), on genotoxicity of zebrafish Danio rerio for 24, 48, 72 and 96-hours acute exposure (level:1, 4, 16, 64 mg/l BA and BX) in semi-static bioassay experiment. For that purpose, peripheral erythrocytes were drawn from caudal vein and Comet assay was applied to assess genotoxicity. Acute (96 hours) exposure and high concentrations of boric acid and borax increases % tail DNA and Olive tail moment. Genotoxicity was found for BA as concentration-dependent and BX as concentration and time dependent manner. In general, significant effects (P < 0,05) on both concentrations and exposure times were observed in experimental groups. DNA damage was highest at 96 h and 24 h for all BX and BA concentrations, respectively in peripheral blood of D. rerio. For the first time, our study demonstrates the effect of waterborne BA and BX exposure on genotoxicity at the molecular level, which may contribute to understanding the mechanism of boric acid and borax-induced genotoxicity in fish. PMID:26862320

Genotoxic effects of boric acid and borax in zebrafish, Danio rerio using alkaline comet assay.

PubMed

Gülsoy, Nagihan; Yavas, Cüneyd; Mutlu, Özal

2015-01-01

The present study is conducted to determine the potential mechanisms of Boron compounds, boric acid (BA) and borax (BX), on genotoxicity of zebrafish Danio rerio for 24, 48, 72 and 96-hours acute exposure (level:1, 4, 16, 64 mg/l BA and BX) in semi-static bioassay experiment. For that purpose, peripheral erythrocytes were drawn from caudal vein and Comet assay was applied to assess genotoxicity. Acute (96 hours) exposure and high concentrations of boric acid and borax increases % tail DNA and Olive tail moment. Genotoxicity was found for BA as concentration-dependent and BX as concentration and time dependent manner. In general, significant effects (P < 0,05) on both concentrations and exposure times were observed in experimental groups. DNA damage was highest at 96 h and 24 h for all BX and BA concentrations, respectively in peripheral blood of D. rerio. For the first time, our study demonstrates the effect of waterborne BA and BX exposure on genotoxicity at the molecular level, which may contribute to understanding the mechanism of boric acid and borax-induced genotoxicity in fish.

Neural Stem Cell Differentiation Using Microfluidic Device-Generated Growth Factor Gradient.

PubMed

Kim, Ji Hyeon; Sim, Jiyeon; Kim, Hyun-Jung

2018-04-11

Neural stem cells (NSCs) have the ability to self-renew and differentiate into multiple nervous system cell types. During embryonic development, the concentrations of soluble biological molecules have a critical role in controlling cell proliferation, migration, differentiation and apoptosis. In an effort to find optimal culture conditions for the generation of desired cell types in vitro , we used a microfluidic chip-generated growth factor gradient system. In the current study, NSCs in the microfluidic device remained healthy during the entire period of cell culture, and proliferated and differentiated in response to the concentration gradient of growth factors (epithermal growth factor and basic fibroblast growth factor). We also showed that overexpression of ASCL1 in NSCs increased neuronal differentiation depending on the concentration gradient of growth factors generated in the microfluidic gradient chip. The microfluidic system allowed us to study concentration-dependent effects of growth factors within a single device, while a traditional system requires multiple independent cultures using fixed growth factor concentrations. Our study suggests that the microfluidic gradient-generating chip is a powerful tool for determining the optimal culture conditions.

Differential Roles for L-Type Calcium Channel Subtypes in Alcohol Dependence

PubMed Central

Uhrig, Stefanie; Vandael, David; Marcantoni, Andrea; Dedic, Nina; Bilbao, Ainhoa; Vogt, Miriam A; Hirth, Natalie; Broccoli, Laura; Bernardi, Rick E; Schönig, Kai; Gass, Peter; Bartsch, Dusan; Spanagel, Rainer; Deussing, Jan M; Sommer, Wolfgang H; Carbone, Emilio; Hansson, Anita C

2017-01-01

It has previously been shown that the inhibition of L-type calcium channels (LTCCs) decreases alcohol consumption, although the contribution of the central LTCC subtypes Cav1.2 and Cav1.3 remains unknown. Here, we determined changes in Cav1.2 (Cacna1c) and Cav1.3 (Cacna1d) mRNA and protein expression in alcohol-dependent rats during protracted abstinence and naive controls using in situ hybridization and western blot analysis. Functional validation was obtained by electrophysiological recordings of calcium currents in dissociated hippocampal pyramidal neurons. We then measured alcohol self-administration and cue-induced reinstatement of alcohol seeking in dependent and nondependent rats after intracerebroventricular (i.c.v.) injection of the LTCC antagonist verapamil, as well as in mice with an inducible knockout (KO) of Cav1.2 in Ca2+/calmodulin-dependent protein kinase IIα (CaMKIIα)-expressing neurons. Our results show that Cacna1c mRNA concentration was increased in the amygdala and hippocampus of alcohol-dependent rats after 21 days of abstinence, with no changes in Cacna1d mRNA. This was associated with increased Cav1.2 protein concentration and L-type calcium current amplitudes. Further analysis of Cacna1c mRNA in the CA1, basolateral amygdala (BLA), and central amygdala (CeA) revealed a dynamic regulation over time during the development of alcohol dependence. The inhibition of central LTCCs via i.c.v. administration of verapamil prevented cue-induced reinstatement of alcohol seeking in alcohol-dependent rats. Further studies in conditional Cav1.2-KO mice showed a lack of dependence-induced increase of alcohol-seeking behavior. Together, our data indicate that central Cav1.2 channels, rather than Cav1.3, mediate alcohol-seeking behavior. This finding may be of interest for the development of new antirelapse medications. PMID:27905406

Dose-dependent effects of isoflurane and dobutamine on cardiovascular function in dogs with experimental mitral regurgitation.

PubMed

Goya, Seijirow; Wada, Tomoki; Shimada, Kazumi; Hirao, Daiki; Tanaka, Ryou

2018-04-18

To investigate the dose-dependent effects of isoflurane and dobutamine on haemodynamics in dogs with experimentally induced mitral valve insufficiency (MI). Experimental, dose-response study. Six healthy Beagle dogs. Dogs with surgically induced MI were anaesthetized once. First, anaesthesia was maintained at an end-tidal isoflurane concentration (Fe'Iso) 1.0% (ISO1.0) for 20 minutes. Then, dobutamine was infused successively at 2, 4, 8 and 12 μg kg -1 minute -1 (DOB2-12) for 10 minutes at each dose rate. Measurements were recorded at each stage. Dobutamine was discontinued and Fe'Iso was increased to 1.5% (ISO1.5) for 20 minutes. Dobutamine was administered similarly to ISO1.0, and cardiovascular variables were recorded. The same sequence was repeated for Fe'Iso 2.0% (ISO2.0). Aortic pressure (AoP) and left atrial pressure (LAP) were recorded by radiotelemetry. The combination method of the pressure-volume loop analysis and transoesophageal echocardiography was used to measure cardiovascular variables: end-systolic elastance (Ees), effective arterial elastance (Ea), Ea/Ees, forward stroke volume (FSV), heart rate (HR), and cardiac output (CO). High isoflurane concentration resulted in reduced Ees and increased Ea/Ees, which indicated low arterial pressure. High-dose dobutamine administration resulted in increased Ees and FSV at all isoflurane concentrations. In ISO1.5 and ISO2.0, HR was lower at DOB4 than baseline (BL) but increased at DOB12 compared with DOB4. CO increased at ≥ DOB8 compared with BL. In ISO1.5 and ISO2.0, systolic and mean AoP increased at ≥ DOB4 and ≥ DOB8, respectively. LAP did not change under all conditions. The dose-dependent hypotensive effect of isoflurane in MI dogs was mainly derived from the decrease in contractility. Dobutamine increased AoP without increasing LAP by increasing the contractility attenuated by isoflurane. Our findings may improve the cardiovascular management of dogs with MI undergoing general anaesthesia with isoflurane. Copyright © 2018 Association of Veterinary Anaesthetists and American College of Veterinary Anesthesia and Analgesia. Published by Elsevier Ltd. All rights reserved.

In vivo antioxidant activity of deacetylasperulosidic Acid in noni.

PubMed

Ma, De-Lu; Chen, Mai; Su, Chen X; West, Brett J

2013-01-01

Deacetylasperulosidic acid (DAA) is a major phytochemical constituent of Morinda citrifolia (noni) fruit. Noni juice has demonstrated antioxidant activity in vivo and in human trials. To evaluate the role of DAA in this antioxidant activity, Wistar rats were fed 0 (control group), 15, 30, or 60 mg/kg body weight per day for 7 days. Afterwards, serum malondialdehyde concentration and superoxide dismutase and glutathione peroxidase activities were measured and compared among groups. A dose-dependent reduction in malondialdehyde was evident as well as a dose-dependent increase in superoxide dismutase activity. DAA ingestion did not influence serum glutathione peroxidase activity. These results suggest that DAA contributes to the antioxidant activity of noni juice by increasing superoxide dismutase activity. The fact that malondialdehyde concentrations declined with increased DAA dose, despite the lack of glutathione peroxidase-inducing activity, suggests that DAA may also increase catalase activity. It has been previously reported that noni juice increases catalase activity in vivo but additional research is required to confirm the effect of DAA on catalase. Even so, the current findings do explain a possible mechanism of action for the antioxidant properties of noni juice that have been observed in human clinical trials.

In Vivo Antioxidant Activity of Deacetylasperulosidic Acid in Noni

PubMed Central

Ma, De-Lu; Chen, Mai; Su, Chen X.; West, Brett J.

2013-01-01

Deacetylasperulosidic acid (DAA) is a major phytochemical constituent of Morinda citrifolia (noni) fruit. Noni juice has demonstrated antioxidant activity in vivo and in human trials. To evaluate the role of DAA in this antioxidant activity, Wistar rats were fed 0 (control group), 15, 30, or 60 mg/kg body weight per day for 7 days. Afterwards, serum malondialdehyde concentration and superoxide dismutase and glutathione peroxidase activities were measured and compared among groups. A dose-dependent reduction in malondialdehyde was evident as well as a dose-dependent increase in superoxide dismutase activity. DAA ingestion did not influence serum glutathione peroxidase activity. These results suggest that DAA contributes to the antioxidant activity of noni juice by increasing superoxide dismutase activity. The fact that malondialdehyde concentrations declined with increased DAA dose, despite the lack of glutathione peroxidase-inducing activity, suggests that DAA may also increase catalase activity. It has been previously reported that noni juice increases catalase activity in vivo but additional research is required to confirm the effect of DAA on catalase. Even so, the current findings do explain a possible mechanism of action for the antioxidant properties of noni juice that have been observed in human clinical trials. PMID:24371540

Effect of Spacecraft Environmental Variables on the Flammability of Fire Resistant Fabrics

NASA Astrophysics Data System (ADS)

Osorio, A. F.; Fernandez-Pello, C.; Takahashi, S.; Rodriguez, J.; Urban, D. L.; Ruff, G.

2012-01-01

Fire resistant fabrics are used for firefighter, racecar drivers as well as astronaut suits. However, their fire resistant characteristics depend on the environment conditions and require study. Particularly important is the response of these fabrics to elevated oxygen concentration environments and radiant heat from a source such as an adjacent fire. In this work, experiments using two fire resistant fabrics were conducted to study the effect of oxygen concentration, external radiant flux and oxidizer flow velocity in concurrent flame spread. Results show that for a given fabric the minimum oxygen concentration for flame spread depends strongly on the magnitude of the external radiant flux. At increased oxygen concentrations the external radiant flux required for flame spread decreases. Oxidizer flow velocity influences the external radiant flux only when the convective heat flux from the flame has similar values to the external radiant flux. The results of this work provide further understanding of the flammability characteristics of fire resistant fabrics in environments similar to those of future spacecrafts.

Calcification response of Pleurochrysis carterae to iron concentrations in batch incubations: implication for the marine biogeochemical cycle

NASA Astrophysics Data System (ADS)

Zou, Xiang; Sun, Shiyong; Lin, Sen; Shen, Kexuan; Dong, Faqin; Tan, Daoyong; Nie, Xiaoqin; Liu, Mingxue; Wei, Jie

2017-12-01

Calcified coccolithophores, a diverse and widely distributed group of marine microalgae, produce biogenic calcite in the form of coccoliths located on the cell surface. Using batch incubations of the coccolithophorid Pleurochrysis carterae, we investigated the responses of this calcification process to iron concentrations by changing the iron supply in the initial culture media from a normal concentration to 1 ppm (parts per million), 5 ppm, and 10 ppm. Time-dependent measurements of cell population, production of inorganic carbon (coccoliths), and organic carbon (organic cellular components) showed that elevated iron supply in the growth medium of P. carterae stimulates carbon sequestration by increasing growth along enhanced photosynthetic activity and calcification. In addition, the acquired time-dependent UV-Vis and FT-IR spectra revealed that iron fertilization-enhanced coccolith calcification is accompanied by a crystalline phase transition from calcite to aragonite or amorphous phase. Our results suggest that iron concentration has a significant influence on the marine carbon cycle of coccolithophores.

Effect of solute atom concentration on vacancy cluster formation in neutron-irradiated Ni alloys

NASA Astrophysics Data System (ADS)

Sato, Koichi; Itoh, Daiki; Yoshiie, Toshimasa; Xu, Qiu; Taniguchi, Akihiro; Toyama, Takeshi

2011-10-01

The dependence of microstructural evolution on solute atom concentration in Ni alloys was investigated by positron annihilation lifetime measurements. The positron annihilation lifetimes in pure Ni, Ni-0.05 at.%Si, Ni-0.05 at.%Sn, Ni-Cu, and Ni-Ge alloys were about 400 ps even at a low irradiation dose of 3 × 10 -4 dpa, indicating the presence of microvoids in these alloys. The size of vacancy clusters in Ni-Si and Ni-Sn alloys decreased with an increase in the solute atom concentration at irradiation doses less than 0.1 dpa; vacancy clusters started to grow at an irradiation dose of about 0.1 dpa. In Ni-2 at.%Si, irradiation-induced segregation was detected by positron annihilation coincidence Doppler broadening measurements. This segregation suppressed one-dimensional (1-D) motion of the interstitial clusters and promoted mutual annihilation of point defects. The frequency and mean free path of the 1-D motion depended on the solute atom concentration and the amount of segregation.

Responses of the antioxidative and biotransformation enzymes in the aquatic fungus Mucor hiemalis exposed to cyanotoxins.

PubMed

Balsano, Evelyn; Esterhuizen-Londt, Maranda; Hoque, Enamul; Lima, Stephan Pflugmacher

2017-08-01

To investigate antioxidative and biotransformation enzyme responses in Mucor hiemalis towards cyanotoxins considering its use in mycoremediation applications. Catalase (CAT), glutathione reductase (GR), and glutathione peroxidase (GPx) in M. hiemalis maintained their activities at all tested microcystin-LR (MC-LR) exposure concentrations. Cytosolic glutathione S-transferase (GST) activity decreased with exposure to 100 µg MC-LR l -1 while microsomal GST remained constant. Cylindrospermopsin (CYN) at 100 µg l -1 led to an increase in CAT activity and inhibition of GR, as well as to a concentration-dependent GPx inhibition. Microsomal GST was inhibited at all concentrations tested. β-N-methylamino-L-alanine (BMAA) inhibited GR activity in a concentration-dependent manner, however, CAT, GPx, and GST remained unaffected. M. hiemalis showed enhanced oxidative stress tolerance and intact biotransformation enzyme activity towards MC-LR and BMAA in comparison to CYN, confirming its applicability in bioreactor technology in terms of viability and survival in their presence.

Effects of electromagnetic radiation exposure on stress-related behaviors and stress hormones in male wistar rats.

PubMed

Mahdavi, Seyed Mohammad; Sahraei, Hedayat; Yaghmaei, Parichehreh; Tavakoli, Hassan

2014-11-01

Studies have demonstrated that electromagnetic waves, as the one of the most important physical factors, may alter cognitive and non-cognitive behaviors, depending on the frequency and energy. Moreover, non-ionizing radiation of low energy waves e.g. very low frequency waves could alter this phenomenon via alterations in neurotransmitters and neurohormones. In this study, short, medium, and long-term exposure to the extremely low frequency electromagnetic field (ELF-EMF) (1 and 5 Hz radiation) on behavioral, hormonal, and metabolic changes in male Wistar rats (250 g) were studied. In addition, changes in plasma concentrations for two main stress hormones, noradrenaline and adrenocorticotropic hormone (ACTH) were evaluated. ELF-EMF exposure did not alter body weight, and food and water intake. Plasma glucose level was increased and decreased in the groups which exposed to the 5 and 1Hz wave, respectively. Plasma ACTH concentration increased in both using frequencies, whereas nor-adrenaline concentration showed overall reduction. At last, numbers of rearing, sniffing, locomotor activity was increased in group receiving 5 Hz wave over the time. In conclusions, these data showed that the effects of 1 and 5 Hz on the hormonal, metabolic and stress-like behaviors may be different. Moreover, the influence of waves on stress system is depending on time of exposure.

Analgesia or addiction?: implications for morphine use after spinal cord injury.

PubMed

Woller, Sarah A; Moreno, Georgina L; Hart, Nigel; Wellman, Paul J; Grau, James W; Hook, Michelle A

2012-05-20

Opioid analgesics are among the most effective agents for treatment of moderate to severe pain. However, the use of morphine after a spinal cord injury (SCI) can potentiate the development of paradoxical pain symptoms, and continuous administration can lead to dependence, tolerance, and addiction. Although some studies suggest that the addictive potential of morphine decreases when it is used to treat neuropathic pain, this has not been studied in a SCI model. Accordingly, the present studies investigated the addictive potential of morphine in a rodent model of SCI using conditioned place preference (CPP) and intravenous self-administration paradigms. A contusion injury significantly increased the expression of a CPP relative to sham and intact controls in the acute phase of injury. However, contused animals self-administered significantly less morphine than sham and intact controls, but this was dose-dependent; at a high concentration, injured rats exhibited an increase in drug-reinforced responses over time. Exposure to a high concentration of morphine impeded weight gain and locomotor recovery. We suggest that the increased preference observed in injured rats reflects a motivational effect linked in part to the drug's anti-nociceptive effect. Further, although injured rats exhibited a suppression of opiate self-administration, when given access to a high concentration, addictive-like behavior emerged and was associated with poor recovery.

Effects of Electromagnetic Radiation Exposure on Stress-Related Behaviors and Stress Hormones in Male Wistar Rats

PubMed Central

Mahdavi, Seyed Mohammad; Sahraei, Hedayat; Yaghmaei, Parichehreh; Tavakoli, Hassan

2014-01-01

Studies have demonstrated that electromagnetic waves, as the one of the most important physical factors, may alter cognitive and non-cognitive behaviors, depending on the frequency and energy. Moreover, non-ionizing radiation of low energy waves e.g. very low frequency waves could alter this phenomenon via alterations in neurotransmitters and neurohormones. In this study, short, medium, and long-term exposure to the extremely low frequency electromagnetic field (ELF-EMF) (1 and 5 Hz radiation) on behavioral, hormonal, and metabolic changes in male Wistar rats (250 g) were studied. In addition, changes in plasma concentrations for two main stress hormones, noradrenaline and adrenocorticotropic hormone (ACTH) were evaluated. ELF-EMF exposure did not alter body weight, and food and water intake. Plasma glucose level was increased and decreased in the groups which exposed to the 5 and 1Hz wave, respectively. Plasma ACTH concentration increased in both using frequencies, whereas nor-adrenaline concentration showed overall reduction. At last, numbers of rearing, sniffing, locomotor activity was increased in group receiving 5 Hz wave over the time. In conclusions, these data showed that the effects of 1 and 5 Hz on the hormonal, metabolic and stress-like behaviors may be different. Moreover, the influence of waves on stress system is depending on time of exposure. PMID:25489427

Surface plasmon resonance measurements of plasma antibody avidity during primary and secondary responses to anthrax protective antigen

PubMed Central

Lynch, Heather E.; Stewart, Shelley M.; Kepler, Thomas B.; Sempowski, Gregory D.; Alam, S. Munir

2014-01-01

Establishment of humoral immunity against pathogens is dependent on events that occur in the germinal center and the subsequent induction of high-affinity neutralizing antibodies. Quantitative assays that allow monitoring of affinity maturation and duration of antibody responses can provide useful information regarding the efficacy of vaccines and adjuvants. Using an anthrax protective antigen (rPA) and alum model antigen/adjuvant system, we describe a methodology for monitoring antigen-specific serum antibody concentration and avidity by surface plasmon resonance during primary and secondary immune responses. Our analyses showed that following a priming dose in mice, rPA-specific antibody concentration and avidity increases over time and reaches a maximal response in about six weeks, but gradually declines in the absence of antigenic boost. Germinal center reactions were observed early with maximal development achieved during the primary response, which coincided with peak antibody avidity responses to primary immunization. Boosting with antigen resulted in a rapid increase in rPA-specific antibody concentration and five-fold increase in avidity, which was not dependent on sustained GC development. The described methodology couples surface plasmon resonance-based plasma avidity measurements with germinal center analysis and provides a novel way to monitor humoral responses that can play a role in facilitating vaccine and adjuvant development. PMID:24316020

Dynamics of Uncrystallized Water, Ice, and Hydrated Protein in Partially Crystallized Gelatin-Water Mixtures Studied by Broadband Dielectric Spectroscopy.

PubMed

Sasaki, Kaito; Panagopoulou, Anna; Kita, Rio; Shinyashiki, Naoki; Yagihara, Shin; Kyritsis, Apostolos; Pissis, Polycarpos

2017-01-12

The glass transition of partially crystallized gelatin-water mixtures was investigated using broadband dielectric spectroscopy (BDS) over a wide range of frequencies (10 mHz to 10 MHz), temperatures (113-298 K), and concentrations (10-45 wt %). Three dielectric relaxation processes (processes I, II, and III) were clearly observed. Processes I, II, and III originate from uncrystallized water (UCW) in the hydration shells of gelatin, ice, and hydrated gelatin, respectively. A dynamic crossover, called the Arrhenius to non-Arrhenius transition of UCW, was observed at the glass transition temperature of the relaxation process of hydrated gelatin for all mixtures. The amount of UCW increases with increasing gelatin content. However, above 35 wt % gelatin, the amount of UCW became more dependent on the gelatin concentration. This increase in UCW causes a decrease in the glass transition temperature of the cooperative motion of gelatin and UCW, which appears to result from a change in the aggregation structure of gelatin in the mixture at a gelatin concentration of approximately 35 wt %. The temperature dependence of the relaxation time of process II has nearly the same activation energy as pure ice made by slow crystallization of ice Ih. This implies that process II originates from the dynamics of slowly crystallized ice Ih.

Effect of surfactants and manufacturing methods on the electrical and thermal conductivity of carbon nanotube/silicone composites.

PubMed

Vilčáková, Jarmila; Moučka, Robert; Svoboda, Petr; Ilčíková, Markéta; Kazantseva, Natalia; Hřibová, Martina; Mičušík, Matej; Omastová, Mária

2012-11-05

The effect of ionic surfactants and manufacturing methods on the separation and distribution of multi-wall carbon nanotubes (CNTs) in a silicone matrix are investigated. The CNTs are dispersed in an aqueous solution of the anionic surfactant dodecylbenzene sulfonic acid (DBSA), the cationic surfactant cetyltrimethylammonium bromide (CTAB), and in a DBSA/CTAB surfactant mixture. Four types of CNT-based composites of various concentrations from 0 to 6 vol.% are prepared by simple mechanical mixing and sonication. The morphology, electrical and thermal conductivity of the CNT-based composites are analyzed. The incorporation of both neat and modified CNTs leads to an increase in electrical and thermal conductivity. The dependence of DC conductivity versus CNT concentration shows percolation behaviour with a percolation threshold of about 2 vol.% in composites with neat CNT. The modification of CNTs by DBSA increases the percolation threshold to 4 vol.% due to the isolation/separation of individual CNTs. This, in turn, results in a significant decrease in the complex permittivity of CNT–DBSA-based composites. In contrast to the percolation behaviour of DC conductivity, the concentration dependence of thermal conductivity exhibits a linear dependence, the thermal conductivity of composites with modified CNTs being lower than that of composites with neat CNTs. All these results provide evidence that the modification of CNTs by DBSA followed by sonication allows one to produce composites with high homogeneity.

Adsorption of Ten Microcystin Congeners to Common Laboratory-Ware Is Solvent and Surface Dependent

PubMed Central

Altaner, Stefan; Puddick, Jonathan; Wood, Susanna A.; Dietrich, Daniel R.

2017-01-01

Cyanobacteria can produce heptapetides called microcystins (MC) which are harmful to humans due to their ability to inhibit cellular protein phosphatases. Quantitation of these toxins can be hampered by their adsorption to common laboratory-ware during sample processing and analysis. Because of their structural diversity (>100 congeners) and different physico-chemical properties, they vary in their adsorption to surfaces. In this study, the adsorption of ten different MC congeners (encompassing non-arginated to doubly-arginated congeners) to common laboratory-ware was assessed using different solvent combinations. Sample handling steps were mimicked with glass and polypropylene pipettes and vials with increasing methanol concentrations at two pH levels, before analysis by liquid chromatography-tandem mass spectrometry. We demonstrated that MC adsorb to polypropylene surfaces irrespective of pH. After eight successive pipet actions using polypropylene tips ca. 20% of the MC were lost to the surface material, which increased to 25%–40% when solutions were acidified. The observed loss was alleviated by changing the methanol (MeOH) concentration in the final solvent. The required MeOH concentration varied depending on which congener was present. Microcystins only adsorbed to glass pipettes (loss up to 30% after eight pipet actions) when in acidified aqueous solutions. The latter appeared largely dependent on the presence of ionizable groups, such as arginine residues. PMID:28383495

Effects of Monovalent Cations on the Sodium-Alanine Interaction in Rabbit Ileum

PubMed Central

Frizzell, Raymond A.; Schultz, Stanley G.

1970-01-01

H, K, Rb, and Li inhibit Na-dependent alanine influx across the brush border of rabbit ileum. Kinetic analysis indicates that H and K behave as competitive inhibitors of influx so that increasing the concentration of H or K in the mucosal solution is kinetically indistinguishable from decreasing the Na concentration. In addition the coupling between alanine and Na influxes is markedly reduced at pH 2.5. With the exception of H and Li, none of these monovalent cations significantly affects carrier-mediated alanine influx in the absence of Na indicating that their inhibitory effects are largely restricted to the Na-dependent fraction of influx. Increasing H concentration from 0.03 to 3 mM does not affect influx in the absence of Na but markedly inhibits influx in the presence of Na. Li significantly enhances alanine influx in the absence of Na. Ag, UO2, and La also inhibit the Na-dependent fraction of alanine influx. These findings suggest that anionic groups having a pKa of approximately 4 are involved in the interaction between Na and the alanine-carrier complex; present evidence implicates carboxylate groups however, phosphoryl residues cannot be ruled out. The previously proposed kinetic model for the Na-alanine interaction has been extended to accommodate these effects of H and other monovalent cations. The mechanistic and physiological implications of these findings are discussed. PMID:5507092

Intestinal absorption of forsythoside A in in situ single-pass intestinal perfusion and in vitro Caco-2 cell models

PubMed Central

Zhou, Wei; Di, Liu-qing; Wang, Juan; Shan, Jin-jun; Liu, Shi-jia; Ju, Wen-zheng; Cai, Bao-chang

2012-01-01

Aim: To investigate the mechanisms underlying the intestinal absorption of the major bioactive component forsythoside A (FTA) extracted from Forsythiae fructus. Methods: An in vitro Caco-2 cell model and a single-pass intestinal perfusion in situ model in SD rats were used. Results: In the in vitro Caco-2 cell model, the mean apparent permeability value (Papp-value) was 4.15×10-7 cm/s in the apical-to-basolateral (AP-BL) direction. At the concentrations of 2.6–10.4 μg/mL, the efflux ratio of FTA in the bi-directional transport experiments was approximately 1.00. After the transport, >96% of the apically loaded FTA was retained on the apical side, while >97% of the basolaterally loaded FTA was retained on the basolateral side. The Papp-values of FTA were inversely correlated with the transepithelial electrical resistance. The paracellular permeability enhancers sodium caprate and EDTA, the P-gp inhibitor verapamil and the multidrug resistance related protein (MRP) inhibitors cyclosporine and MK571 could concentration-dependently increase the Papp-values, while the uptake (OATP) transporter inhibitors diclofenac sodium and indomethacin could concentration-dependently decrease the Papp-values. The intake transporter SGLT1 inhibitor mannitol did not cause significant change in the Papp-values. In the in situ intestinal perfusion model, both the absorption rate constant (Ka) and the effective permeability (Peff-values) following perfusion of FTA 2.6, 5.2 and 10.4 μg/mL via the duodenum, jejunum and ileum had no significant difference, although the values were slightly higher for the duodenum as compared to those in the jejunum and ileum. The low, medium and high concentrations of verapamil caused the largest increase in the Peff-values for duodenum, jejunum and ileum, respectively. Sodium caprate, EDTA and cyclosporine resulted in concentration-dependent increase in the Peff-values. Diclofenac sodium and indomethacin caused concentration-dependent decrease in the Peff-values. Mannitol did not cause significant change in the Papp-values for the duodenum, jejunum or ileum. Conclusion: The results suggest that the intestinal absorption of FTA may occur through passive diffusion, and the predominant absorption site may be in the upper part of small intestine. Paracellular transport route is also involved. P-gp, MRPs and OATP may participate in the absorption of FTA in the intestine. The low permeability of FTA contributes to its low oral bioavailability. PMID:22773077

Activation of rat intestinal mucosal mast cells by fat absorption.

PubMed

Ji, Yong; Sakata, Yasuhisa; Yang, Qing; Li, Xiaoming; Xu, Min; Yoder, Stephanie; Langhans, Wolfgang; Tso, Patrick

2012-06-01

Previous studies have linked certain types of gut mucosal immune cells with fat intake. We determined whether fat absorption activates intestinal mucosal mast cells (MMC), a key component of the gut mucosal immune system. Conscious intestinal lymph fistula rats were used. The mesenteric lymph ducts were cannulated, and the intraduodenal (i.d.) tubes were installed for the infusion of Liposyn II 20% (an intralipid emulsion). Lymphatic concentrations of histamine, rat MMC protease II (RMCPII), a specific marker of rat intestinal MMC degranulation, and prostaglandin D(2) (PGD(2)) were measured by ELISA. Intestinal MMC degranulation was visualized by immunofluorescent microscopy of jejunum sections taken at 1 h after Liposyn II gavage. Intraduodenal bolus infusion of Liposyn II 20% (4.4 kcal/3 ml) induced approximately a onefold increase in lymphatic histamine and PGD(2), ∼20-fold increase in lymphatic RMCPII, but only onefold increase in peripheral serum RMCPII concentrations. Release of RMCPII into lymph increased dose dependently with the amount of lipid fed. In addition, i.d. infusion of long-chain triacylglycerol trilinolein (C18:2 n-6, the major composite in Liposyn II) significantly increased the lymphatic RMCPII concentration, whereas medium-chain triacylglycerol tricaprylin (C8:0) did not alter lymph RMCPII secretion. Immunohistochemistry image revealed the degranulation of MMC into lamina propria after lipid feeding. These novel findings indicate that intestinal MMC are activated and degranulate to release MMC mediators to the circulation during fat absorption. This action of fatty acid is dose and chain length dependent.

Activation of rat intestinal mucosal mast cells by fat absorption

PubMed Central

Sakata, Yasuhisa; Yang, Qing; Li, Xiaoming; Xu, Min; Yoder, Stephanie; Langhans, Wolfgang; Tso, Patrick

2012-01-01

Previous studies have linked certain types of gut mucosal immune cells with fat intake. We determined whether fat absorption activates intestinal mucosal mast cells (MMC), a key component of the gut mucosal immune system. Conscious intestinal lymph fistula rats were used. The mesenteric lymph ducts were cannulated, and the intraduodenal (i.d.) tubes were installed for the infusion of Liposyn II 20% (an intralipid emulsion). Lymphatic concentrations of histamine, rat MMC protease II (RMCPII), a specific marker of rat intestinal MMC degranulation, and prostaglandin D2 (PGD2) were measured by ELISA. Intestinal MMC degranulation was visualized by immunofluorescent microscopy of jejunum sections taken at 1 h after Liposyn II gavage. Intraduodenal bolus infusion of Liposyn II 20% (4.4 kcal/3 ml) induced approximately a onefold increase in lymphatic histamine and PGD2, ∼20-fold increase in lymphatic RMCPII, but only onefold increase in peripheral serum RMCPII concentrations. Release of RMCPII into lymph increased dose dependently with the amount of lipid fed. In addition, i.d. infusion of long-chain triacylglycerol trilinolein (C18:2 n-6, the major composite in Liposyn II) significantly increased the lymphatic RMCPII concentration, whereas medium-chain triacylglycerol tricaprylin (C8:0) did not alter lymph RMCPII secretion. Immunohistochemistry image revealed the degranulation of MMC into lamina propria after lipid feeding. These novel findings indicate that intestinal MMC are activated and degranulate to release MMC mediators to the circulation during fat absorption. This action of fatty acid is dose and chain length dependent. PMID:22461027

Effects of 2-deoxy-D-glucose administration on immune parameters in mice

NASA Technical Reports Server (NTRS)

Dreau, D.; Morton, D. S.; Foster, M.; Fowler, N.; Sonnenfeld, G.

1998-01-01

Physical exercise and diet alterations have been shown to affect immune parameters. Similar effects are also induced by the administration of the non-metabolizable glucose analog, 2-deoxy-D-glucose (2-DG). The current study was designed to characterize the effects of glucoprivation induced by 2-DG administration on leukocyte subset distribution and function. BDF1 mice (n = 8 per group) were injected intraperitoneally one or three times with 0, 500, 750, 1000 or 1500 mg/kg of 2-DG. Two hours after the last injection of 2-DG, immunological parameters were analyzed. A dose-dependent increase in plasma glucose concentrations of mice injected once with up to 1500 mg/kg of 2-DG was observed (p < 0.001). After either one or three injections of up to 1500 mg/kg of 2-DG, corticosterone levels, leukocyte counts in the spleen, and CD3+ cells in the thymus increased. In vitro proliferation of partially purified lymphocytes from the spleen in the presence of both concanavalin-A and lipopolysaccharide decreased in a dose dependent manner (p < 0.05). In addition, after three injections, the proportion of both thymocytes and splenocytes bearing alphabeta-TCR increased as the concentration of 2-DG increased (p < 0.01). These results demonstrate that 2-DG administration induced dose-dependent changes in both thymus and spleen cell distribution and function.

An experimental study on the magnetic and exchange bias properties of selected Mn rich Ni-Mn-Ga based Heusler alloys

NASA Astrophysics Data System (ADS)

Albagami, Abdullah Mohamed

In this Thesis project, an experimental study on the magnetic and exchange bias properties of a series of polycrystalline Ni1.7-xMn1.7+x Ga0.6 alloys have been investigated by x-ray diffraction, dc magnetization, and ac susceptibility measurements. X-ray diffraction measurement showed that all prepared samples have a tetragonal L10 martensitic structure at room temperature. Scanning electron microscopy measurements show that the compounds are single phase. With increasing Mn concentration x, the lattice parameters marginally increases. The temperature dependence of magnetization data show two distinct transitions in the alloys. At lower temperatures, a peak in the data is observed while the ferromagnetic to paramagnetic transition occurs at higher temperatures. With increasing Mn concentration, the temperature of both transitions increases. Thermomagnetic irreversibility is observed in the magnetization data of all alloys. The ac susceptibility measurements on the materials show the existence of frequency dependence, which suggest that the thermomagnetic irreversibility in the magnetization data is due to the spin glass like ground state in the alloys. The spin glass like ground state with competing magnetic interactions result in the observation of double-shifted hysteresis loop and exchange bias effects in the alloys. The magnitude of the exchange bias field is strongly dependent on the cooling field.