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Biomedical subjects

M Myers

Publications and source records attributed to M Myers.

140 records · Page 8Linked to original sources
PubMedDate not supplied

Bioavailability of terfenadine in man.

Fourteen normal male subjects were given either 60mg or 180mg of terfenadine suspension in a randomized two-way crossover study. Peak plasma concentrations of 1.544 +/- 0.726 (mean +/- S.D.) ng ml-1 were obtained in 0.786 h following the 60 mg dose and displayed an AUC or 11.864 +/- 3.369 ng h ml-1. Whereas peak plasma concentrations of 4.519 +/- 2.002 ng ml-1 in 1.071 +/- 0.514 h were obtained following the 180 mg dose. The AUC following the 180 mg dose was 44.341 +/- 22.041 ng h ml-1. When 60 mg of 14C terfenadine was given to six additional subjects, the peak plasma concentrations of 351 +/- 43 ng equivalents per ml were obtained in 1.67 +/- 0.41 h and the AUC was 2297.71 +/- 310.85 ng-equivalents h ml-1. This indicates that approximately 99.5 per cent of the terfenadine related material that is absorbed undergoes biotransformation. Urinary excretion of 14C accounted for 39.89 +/- 5.29 per cent of the dose while 60.58 +/- 2.44 per cent of the dose was recovered in the feces in twelve days. Thin-layer chromatographic (TLC) examination of fecal extracts showed only a trace of material chromatographing with terfenadine. This may indicate that the 14C present in the feces is not due to lack of absorption.

Benzhydryl Compounds↗
PubMedDate not supplied

Penetration of the holmium:YAG laser through fluid.

PURPOSE: The 2.1-microns pulsed holmium:yttrium-aluminum-garnet (Ho:YAG) laser combines the properties of transmissibility down a flexible silica fiber, enabling percutaneous or endoscopic use, with high water absorption, suggesting good safety characteristics. Laser attenuation in practice, however, is an extremely complex process. The authors studied its effective penetration through blood, bile, urine, saline, and contrast media. MATERIALS AND METHODS: With use of a fiberoptically directed beam and a laser power meter, penetration was measured in vitro with the fiber tip separated from the medium by 5 cm (noncontact mode) and with the fiber tip immersed (contact mode). Logarithm of energy falloff was measured against fluid thickness. Attenuation coefficients (mu) and half value layer (HVL) distances (estimated thickness of fluid needed to have power) were measured. RESULTS: In noncontact mode, power falloff was exponential. Non-sanguinous media had similar values for mu and HVL (mu = 2.24-2.70 mm-1 and HVL = 0.26-0.31 mm) close to theoretical predictions. Blood caused significantly (P < .05) more attenuation (mu = 5.15 mm-1, HVL = 0.13 mm). In contact mode, attenuation was much more complex with "plateau" distances of up to 1.2 mm, below which attenuation was negligible. The HVL distances ranged from 0.9 to 1.8 mm and were up to 14 times higher. The main reason is probably the formation of microcavities around the fiber tip. CONCLUSION: The effective penetration of this laser when immersed may be several times that predicted, with important clinical implications.

Absorption↗
PubMedDate not supplied

Role strain.

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Adaptation, Psychological↗
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Studies on the effects of dansylcadaverine and related compounds on receptor-mediated endocytosis in cultured cells.

It has been suggested that cellular transglutaminases may play an important role in the process of receptor-mediated endocytosis. We have examined this premise by investigating the receptor-mediated endocytosis of two proteins, epidermal growth factor and alpha 2 macroglobulin in cells that are deficient in transglutaminases. We find that endocytic activity is normal in these cells, ruling out an obligatory role for transglutaminases in endocytosis. We do find, however, that dansylcadaverine is not an inhibitor of endocytosis in cells that lack transglutaminase activity. Immunofluorescent localization of dansylcadaverine in dansylcadaverine-treated cells demonstrates incorporation of the amino into endocytic vesicles. We believe that covalent coupling of dansylcadaverine to cellular membranes may account for its ability to interfere with endocytosis in certain susceptible cells.

Acyltransferases↗