PURPOSE To investigate toxicity associated with buffers commonly used in topical ocular drug formulations using a human corneal-limbal epithelial (HCLE) and a human conjunctival epithelial (HCjE) cell model. METHODS HCLE and HCjE cells were incubated for 10, 30, or 60 minutes with 4 different buffers based on borate, citrate, phosphate, and Tris-HCl at 10, 50, and 100 mM concentrations. To de...

We describe an enzymic method for conveniently measuring citrate in serum or urine. Interfering enzyme proteins are removed by a disposable ultrafilter ("Ultrafree"; Worthington Diagnostics), obviating the need for hazardous protein precipitants. A 50 mmol/L Tris buffer adequately controls pH, no lactate dehydrogenase is necessary in the reagents, and the reaction of citrate catalyzed by citrat...

One ejaculate from each Of 13 bulls was used to determine the influence of glycerol level on post-thaw susceptibili ty of spermatozoa in French straws to cold shock. Treatments were arranged factorially and included yolk-Tris and yolk-citrate diluents; 7, 9 and 11% glycerol ;and exposure to 1, 20 or 37 C water baths for 3 rain immediately post-thaw. Percentage of motile spermatozoa and percenta...

The objective of this study was to evaluate effect of different concentrations of catalase in two extenders on motility, viability and lipid peroxidation bull spermatozoa during semen freezing process. Thirty ejaculates collected from ten Holstein bulls were pooled and evaluated at 37 °C. Pool ejaculated was split into two main experimental groups, 1 and 2. In experiment 1, specimen was dilute...

the objective of this study was to evaluate effect of different concentrations of catalase in two extenders on motility, viability and lipid peroxidation bull spermatozoa during semen freezing process. thirty ejaculates collected from ten holstein bulls were pooled and evaluated at 37 °c. pool ejaculated was split into two main experimental groups, 1 and 2. in experiment 1, specimen was diluted...

Cultures of Escherichia coli growing exponentially in Trisacetate medium were subjected to nutritional shift-up and the pool size of guanosine 5’-diphosphate-3’-diphosphate (ppGpp) as well as the rates of protein synthesis and net RNA synthesis were determined. In the shift to a rich medium (glucose plus 19 amino acids plus hypoxanthine) the basal level of ppGpp falls immediately with a decay c...

Rhodopseudomonas gelatinosa grows on citrate anaerobically in the light. Under aerobic conditions citrate cannot be utilized. Citrate is rapidly fermented by Rps. gelatinosa in the dark, and this fermentation is associated with limited growth (one generation). Anaerobically in the light citrate is decomposed much faster than its catabolic products can be used for the synthesis of cellular mater...

Cultures of escherichia coli growing exponentially in Trisacetate medium were subjected to nutritional shift-up and the pool size of guanosine 5'-3'-diphosphate-3'diphosphate (ppGpp) as well as the rates of protein synthesis and net RNA synthesis were determined. In the shift to a rich medium (glucose plus 19 amino acids plus hypoxanthine) the basal level of ppGpp falls immediately with a decay...

The title compound 4 has been prepared in four steps from ethylglycinate in 63% overall yield. This amino analog of citric acid has been co-crystallized with the class A beta-lactamase BS3 of Bacillus licheniformis and the structure of the complex fully analyzed by X-ray diffraction. Tris-ethyl aminocitrate 3 and the free tris-acid 4 have been tested against a member beta-lactamase from all dis...

The experiments were carried out to evaluate a simple method of freezing rabbit spermatozoa. The effect of glucose, lactose or sucrose on post-thawing sperm quality was studied. The results showed that addition of sucrose improved motility and acrosomal integrity (57% of progressive motile spermatozoa vs 43% and 42%, and 68% of normal acrosome vs 56 and 57%, sucrose, lactose and glucose, respec...