PubMed · 5900740
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R J Furie. 1966. Urine specific gravity and renal function.. https://pubmed.ncbi.nlm.nih.gov/5900740/
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BACKGROUND AND OBJECTIVE: Laser-assisted tissue repair is often accompanied by a high dehiscence rate, which may be due to alterations in suture material after laser exposure. The goal of this study was to investigate the effect of CO2 laser irradiation on the tensile strength of microsurgical suture material. STUDY DESIGN/MATERIALS AND METHODS: 10-0 nylon and 25 microns stainless steel threads were exposed to 12 combinations of power densities (62, 124, and 186 W/cm2) and pulse durations (0.5, 1, 2, 3 s) and tested on a tensometer for their tensile strength. RESULTS: At power densities of 186 W/cm2, the 10-0 nylon thread disrupted during laser irradiation, regardless of pulse duration. This was also the case at power densities of 124 C/cm2 for 2 s and 3 s pulse duration. At 124 W/cm2 for 0.5 and 1 s, the tensile strength decreased with 70% relative to the control. At 62 W/cm2, the tensile strength gradually decreased from 100% (0.5 s pulse duration) to 50% (3 s pulse duration) relative to control. Stainless steel thread resisted all laser irradiations. CONCLUSIONS: The 10-0 nylon thread is significantly compromised by irradiation with the CO2 milliwatt laser and therefore meticulous care should be taken not be irradiate the sutures during laser tissue welding.
Vacuolar-type H(+)-ATPases (V-ATPases) are ubiquitous in eukaryote endomembranes, where they are responsible for lumenal acidification. The ratios of H+ translocated per ATP hydrolyzed (which may be important in controlling the activity of these pumps) have previously been found to be variable, noninteger and sensitive to cytosolic as well as lumenal pH. The mechanistic implications of these findings are explored here with reaction kinetics. Experimental data for this analysis comprise supra- and superlinear V-ATPase current-voltage relationships, isolated as bafilomycin-sensitive currents in vacuolar membranes from Beta using the "whole vacuole" patch clamp configuration. Whereas simple models with one reaction cycle fail to provide an adequate description of the data (mainly because of a weak sensitivity of the zero-current voltage to the transmembrane pH gradient), a model with two linked reaction loops allowing partial coupling of H+ translocation to ATP hydrolysis does provide good descriptions. All experimental data obtained with the same vacuolar pH (4.3) could be reduced to a model with eleven independent parameters. Best fits have been obtained on the basis of a binding domain possessing 3 H+ binding sites per ATP hydrolyzed and a net charge of -2 when unoccupied. The enzyme could reorientate its access site between the vacuolar and cytoplasmic side when zero, one or three H+ are bound.
It was recently demonstrated that endo-N-acetyl-beta-D-glucosaminidases (ENGase) acting on N-glycosylproteins are produced by myxobacteria. In this study, it was shown that the secretion of ENGase during vegetative growth of Myxococcus xanthus was cell-density-dependent. The activity produced per cell increased up to 6 x 10(8) cells/ml and stabilized thereafter (maximum level). Two of the developmental mutants used in this study (bsgA and csgA) were locked for ENGase secretion into the maximum level regardless of cell density. To explain the pattern of ENGase secretion, we postulated the presence of a molecule that induces the enzyme until it reaches a proper concentration threshold. Although the chemical structure of this cell density signal was not determined during this study, its occurrence during vegetative growth of M. xanthus was strongly suggested by the results.