Background & Aims: Oxidative stress leads to a rapid initial loss of liver cell volume, but the adaptive mechanisms that serve to restore volume have not been defined. This study aimed to evaluate ...the functional interactions between oxidative stress, cell volume recovery, and membrane ion permeability.
Methods: In HTC rat hepatoma cells, oxidative stress was produced by exposure to H
2O
2 or
D-alanine plus
D-amino acid oxidase (40 U/mL).
Results: Oxidative stress resulted in a rapid decrease in relative cell volume to 0.85 ± 0.06. This was followed by an ~100-fold increase in membrane cation permeability and partial volume recovery to 0.97 ± 0.05 of original values. The volume-sensitive conductance was permeable to Na
+ ≃ K
+ >> Tris
+, and whole-cell current density at −80 mV increased from −1.2 pA/pF at 10
−,5 mol/L H
2O
2 to −95.1 pA/pF at 10
−,2 mol/L H
2O
2. The effects of H
2O
2 were completely inhibited by dialysis of the cell interior with reduced glutathione, and were markedly enhanced by inhibition of glutathione synthase.
Conclusions: These findings support the presence of dynamic functional interactions between cell volume, oxidative stress, and membrane Na
+ permeability. Stress-induced Na
+ influx may represent a beneficial adaptive response that partially restores cell volume over short periods, but sustained cation influx could contribute to the increase in intracellular Na
+ and Ca
2+ associated with cell injury and necrosis.
GASTROENTEROLOGY 2000;118:395-403
Time dependencies of interband photoluminescence are studied in InGaAsSb/AlGaAsSb quantum well structures with various barrier materials and quantum well widths. The experimentally determined ...dependencies of photoluminescence intensity on the optical pumping level are compared with calculated dependencies of photoluminescence intensity on the nonequilibrium carrier concentration. Time of charge carrier trapping into quantum wells and the energy relaxation time related to the polar optical phonon emission were obtained from analysis of the photoluminescence dynamics at different optical pumping levels. The recombination rates with respect to nonradiative Shockley–Read–Hall and Auger recombination were determined. It is shown that, at certain parameter sets, resonant Auger recombination can exist in InGaAsSb/AlGaAsSb quantum well structures, which should results in the decrease of the concentration of carriers taking part in the radiative recombination.
•Resonant Auger recombination between the first electron, heavy hole and SO-split subbands is experimentally observed.•Times of charge carrier capture into QWs and emission of PO phonon in InGaAsSb/InAlGaAsSb QWs are experimentally determined.•The recombination rate with respect to nonradiative Shockley–Read–Hall and Auger recombination is determined.
Physiological increases in liver cell volume lead to an adaptive response that includes opening of membrane Cl− channels, which is critical for volume recovery. The purpose of these studies was to ...assess the potential role for protein kinase C (PKC) as a signal involved in cell volume homeostasis. Studies were performed in HTC rat hepatoma and Mz‐ChA‐1 human cholangiocarcinoma cells, which were used as model hepatocytes and cholangiocytes, respectively. In each cell type, cell volume increases were followed by: 1) translocation of PKCα from cytosolic to particulate (membrane) fractions; 2) a 10‐ to 40‐fold increase in whole‐cell membrane Cl− current density; and 3) partial recovery of cell volume. In HTC cells, the volume‐dependent Cl− current response (−46 ± 5 pA/pF) was inhibited by down‐regulation of PKC (100 nmol/L phorbol 12‐myristate 13‐acetate for 18 hours PMA; −1.97 ± 1.5 pA/pF), chelation of cytosolic Ca2+ (2 mmol/L EGTA; −5.3 ± 4.0 pA/pF), depletion of cytosolic adenosine triphosphate (ATP) (3 U/mL apyrase; −12.58 ± 1.45 pA/pF), and by the putative PKC inhibitor, chelerythrine (25 μmol/L; −7 ± 3 pA/pF). In addition, PKC inhibition by chelerythrine and calphostin C (500 nmol/L) prevented cell volume recovery from swelling. Similar results were obtained in Mz‐ChA‐1 biliary cells. These findings indicate that swelling‐induced activation of PKC represents an important signal coupling cell volume to membrane Cl− permeability in both hepatic and biliary cell models.
Statement of problem. Contamination of removable prostheses with microorganisms, particularly Candida albicans, is a common clinical problem. Microban, a broad-spectrum antimicrobial containing ...triclosan, recently has been proposed to inhibit microbial growth. Purpose. This study aimed to determine whether the addition of Microban to PermaSoft denture liner prevents the growth of C albicans and affects the cytotoxicity of the PermaSoft material. Material and methods. Experimental specimen disks (5 × 1 mm each) with and without incorporated Microban were fabricated aseptically (n = 6) against polyester film to produce a smooth surface. To assess the cytotoxic effect of Microban, the MTT assay was used. To determine the effect of Microban on the growth of C albicans, disks were placed in Transwell dishes, covered with Sabouraud's broth containing an ATCC strain of C albicans, and incubated at 37°C for 24 hours. Wells containing fluorocarbon resin disks or broth alone served as controls. The disks were rinsed to remove unattached C albicans and then sonicated in sterile water to remove surface organisms. Serial dilutions of the water extracts were plated on Sabouraud's agar and returned to the incubator for 24 hours. Colonies were counted with a Brunswick Colony Counter. Growth of C albicans in the internal aspects of the specimens was determined in a manner as previously described, with the exception that the specimens were sonicated to remove surface organisms, minced, and sonicated once more before making serial dilutions. The results were compared with ANOVA and Tukey intervals (α=.05). Results. The number of colonies formed ranged from 17 to 31 × 105 (mean = 23 ± 4 × 105) and 14 to 69 × 105 (mean = 32 ± 20 × 105) for the PermaSoft with and without Microban groups, respectively. There was no statistically significant difference between PermaSoft with and without Microban. Conclusion. The addition of Microban did not significantly alter the cytotoxicity of the PermaSoft denture lining material or reduce the adherence of viable C albicans to the surface of PermaSoft material after 24 hours. (J Prosthet Dent 2001;85:352-6.)
An SAR study that identified a series of thienopyridine-based potent IkappaB Kinase beta (IKK beta ) inhibitors is described. With focuses on the structural optimization at C sub(4) and C sub(6) of ...structure 1 (Fig. 1), the study reveals that small alkyl and certain aromatic groups are preferred at C sub(4), whereas polar groups with proper orientation at C sub(6) efficiently enhance compound potency. The most potent analogues inhibit IKK beta with IC sub(50)s as low as 40 nM, suppress LPS-induced TNF- alpha production in vitro and in vivo, display good kinase selectivity profiles, and are active in a HeLa cell NF-kappaB reporter gene assay, demonstrating that they directly interfere with the NF-kappaB signaling pathway.
When used in combination with chelating agents (EDTA, EGTA, citrate, phosphate), the bacteriocin nisin is effective for reducing populations of gram-negative bacteria in vitro. This study examined ...parameters (buffers, temperature presence of divalent cations) that affect nisin inhibition of Escherichia coli O157:H7 and Salmonella typhimurium. Approximately 7 log(10) colony-forming units (CFU) per ml of E. coli and S. typhimurium were treated in PBS or MOPS buffers containing 50 micrograms/ml of purified nisin, alone or in combination with 500 mM lactate, 100 mM citrate, 50 mM EDTA, and 1% (wt/vol) sodium hexametaphosphate (pH 7.0) at 37 degrees C for 60 min or 5 degrees C for 30 min. Surviving bacterial populations were compared to untreated controls (buffers without nisin). Data indicated that treatments with nisin in buffers resulted in reductions of 4.30 and 2.30 log(10) CFU/ml of E. coli and S. typhimurium, respectively, as compared to untreated controls. Population reductions ranging from 2.29 to 5.49 log(10) CFU/ml were observed when cells were treated with nisin and chelator combinations at either 37 degrees for 60 min or 5 degrees C for 30 min. The addition of magnesium and calcium to buffers with nisin decreased inhibition. Data obtained from spectrophotometric experiments indicated that treatments were causing the release of cellular constituents. However, transmission electron microscopy (TEM) analyses were inconclusive, since cellular membranes did not appear to be disrupted
We present an active anti-latching system for superconducting nanowire single-photon detectors. We experimentally test it against a bright-light attack, previously used to compromise security of ...quantum key distribution. Although our system detects continuous blinding, the detector is shown to be partially blindable and controllable by specially tailored sequences of bright pulses. Improvements to the countermeasure are suggested.
Introduction: AAV2 delivery of the RPE65 cDNA to the retina of blind RPE65-deficient dogs or rd12 mice restores vision as determined electrophysiologically and behaviorally. This strategy is being ...considered for human trials in RPE65-associated Leber congenital amaurosis, but safety and dose-efficacy within a non-toxic range with this vector have not been defined. Here we report the results of toxicology and biodistribution studies in two mammalian species, dogs and rats. Methods: Vector related pathology and spread after subretinal delivery of AAV2-CBA-RPE65 was studied in RPE65-mutant dogs and normal Spague-Dawley rats. Doses of vector delivered bracketed those intended for the clinical study. Results: There was no systemic toxicity at any vector dose in either species. In dogs ocular examinations showed mild or moderate inflammation that resolved over an initial 3-month period. Retinal histopathology indicated that traumatic lesions from the injection were common, but retinal thinning within the injection region only occurred at the highest vector doses. Biodistribution studies were also performed in RPE65-mutant dogs at various times after vector injection and in normal rats at about 2 weeks and 2 months post-injection. Vector DNA was not widespread outside the injected eye with blood and gonadal tissue consistently negative. Concomitant dose-response results in the RPE65-mutant dogs indicated that the highest 1.5 log unit range of vector doses was efficacious. Conclusions: Given the efficacy and toxicity limits defined in this study, a range for safe vector dose escalation of subretinal AAV2-CBA-RPE65 is suggested for initial human trials.
We have developed a fabrication process for GHz-counting-rate, single-photon, high-detection-efficiency, NbN, nanowire detectors. We have demonstrated two processes for the device patterning, one ...based on the standard polymethylmethacrylate (PMMA) organic positive-tone electron-beam resist, and the other based on the newer hydrogen silsesquioxane (HSQ) negative-tone spin-on-glass resist. The HSQ-based process is simple and robust, providing high resolution and the prospect of high fill-factors. Initial testing results show superconductivity in the films, and suggest that the devices exhibit photosensitivity.
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