Organization and emergence of a mixed GABA-glycine retinal circuit that provides inhibition to mouse ON-sustained alpha retinal ganglion cells

1. Download : Download high-res image (164KB)
2. Download : Download full-size image

     

Estimation of ethanol in fermentation broth by solvent extraction and gas chromatography

Ethanol from fermentation is usually estimated by gas chromatography after centrifuging or distilling the broth. In this paper a more efficient and rapid method is described in which ethanol is extracted by an organic solvent such as n-butanol and the extract is analysed by gas chromatography. The distribution factor determined has a value close to unity and is dependent on ethanol concentration, but independent of sugar concentration.     

Hemagglutination (fimbriae) and hydrophobicity in adherence ofSerratia marcescens to urinary tract epithelium and contact lenses

The capacity of 59 isolates of Serratia marcescens, obtained from urinary tract infections, wounds, and contact lenses or their paraphernalia, to agglutinate erythrocytes from different animal species was tested. Three main patterns were found: mannose-sensitive agglutination of guinea-pig, fowl or horse erythrocyte; mannose-resistant agglutination of chicken or pigeon erythrocytes alone or in combination with mannose-sensitive agglutination; and no agglutination. Hemagglutination capacity was associated with isolates from urinary tract infection, but not with isolates associated with contact lenses. Adherence to human urinary tract epithelium did not correlate with the hemagglutination patterns nor with the origin of the isolates. Some strains of different hemagglutination pattern were selected for the study of hydrophobicity and adherence to contact lens polymers. Hydrophobicity, as determined by degree of partition in hexadecane and water (BATH-values), correlated neither with degree of adherence to contact lens polymers nor with the hemagglutination pattern. For a representative strain there was an excellent correlation (r2 = 0.98) between adherence and the water content (hydrophobicity) of the lens polymers. These results suggest that, as with tissues, other factors interact with hydrophobicity in causing adherence to plastics.     

Activity of an insoluble antimicrobial quaternary amine complex in plastics

Summary Growth and survival ofStaphylococcus aureus, Pseudomonas aeruginosa., Klebsiella pneumoniae andAspergillus niger were reduced by a low-solubility polysubstituted.-quaternary amine complex (Intersept^R) processed into the matrices of ethylene vinyl acetate, polystyrene and polyethylene., Recoveries of challenge microorganisms from agar film overlays and determination of the effects of the complex on radiolabelled-leucine transport by adhered cells and bacterial biofilms were more suitable for assessing inhibitory efficacies than standard agar diffusion or serial dilution procedures.     

Partition coefficient of bovine serum albumin in two-phase aqueous systems

Summary We measured partition coefficients of bovine serum albumin in the following two-phase aqueous systems: polyethylene glycol-dextran and polyethylene glycol-potassium phosphate. We report the effects on partition coefficients of variables such as relative molecular masses of polyethylene glycol and dextran, phase composition and temperature.Contribution of National Bureau of Standards, not subject to copyright.     

Studies on triacylglycerol ester hydrolase from bat adipose tissue

Triacylglycerol ester hydrolase was isolated from bat adipose tissue and characterized. The partially purified enzyme had pH optimum of 8.6 and a K_m value of 0.6 mM. The enzyme was denaturated upon freezing and thawing, which was prevented by 25% glycerol. The enzyme was activated by EDTA and NaCl, while it was inhibited by serum and bovine serum albumin. Heparin, sodium fluoride and diisopropyl fluorophosphate had no effect on triacylglycerol ester hydrolase activity. It hydrolyzed triglycerides partially. Triacylglycerol ester hydrolase lost its activity during delipidation but it was reactivated by endogenous lipids and phospholipids, viz. phosphatidyl ethanolamine, phosphatidyl choline and sphingomyelin. The enzyme shows kinetic properties altogether different from lipoprotein lipase and hormone sensitive lipase     

Radiopacity additives in silicone stent materials reduce in vitro bacterial adherence

In vitro adherence of the nosocomial pathogensPseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis, Serratia marcescens, andCandida albicans to select radiopaque silicone compounds was lower than that observed for the base silicone (p<0.03). Except forE. coli ATCC 11775 andCandida albicans, all microorganisms showed significantly lower adherence to a silicone compound impregnated with tantalum in comparison with a silicone compound impregnated with barium sulfate (p<0.05). Surface hydrophobicity of the silicone compounds did not show a direct correlation with the concentration of radiopacity additives or with degree of bacterial adherence. Scatchard analyses of data indicated that the number of adherence sites forP. aeruginosa on the base silicone, BaSO₄-silicone, and Ta-silicone were 9.2×10⁶ per mm², 6.1×10⁶ per mm², and 3.7×10⁶ per mm² respectively. As determined by the Langmuir adsorption isotherm, the dissociation constants for adheredP. aeruginosa to the base silicone, BaSO₄-silicone, and Ta-silicone were 2.50×10³ mm⁴, 1.45×10³ mm⁴, and 6.27×10³ mm⁴ respectively.Pseudomonas aeruginosa demonstrated first order kinetics of adherence to the silicone compounds with a half saturation time of 4.15 h for the base silicone, 1.06 h for the BaSO₄-silicone, and 2.14 h for the Ta-silicone. The use of Ta-silicone stents may delay the development of ascending urinary tract infections.