Search PubMed⌕ Search

Biomedical subjects

M Wieder

Publications and source records attributed to M Wieder.

8 recordsLinked to original sources
PubMed1983

Regulation of oxytocin receptor concentration in rat uterine explants by estrogen and progesterone.

Incubation of uterine explants from immature rats with 0.01-100 ng of 17 beta-estradiol/mL resulted in approximately a fivefold increase in the number of oxytocin receptors per milligram of protein in 48 h. This increase was maintained for at least an additional 48 h in the presence of estrogen. When the explants were incubated with 1 microgram progesterone/mL from the outset, the concentration of oxytocin receptors was the same as initial (0 time) levels. The estrogen-induced increase in oxytocin receptor concentration was blocked by incubation with cycloheximide, an inhibitor of protein synthesis. Once increased, however, the concentration of oxytocin receptors exhibited no turnover for at least a 48-h period in the presence of estrogen. The addition of progesterone and estrogen to explants with elevated receptor levels resulted in almost a 60% reduction in oxytocin receptor concentration by 24 h, with no change in affinity of the receptor for oxytocin. The reduction in receptor concentration by progesterone was not prevented by cycloheximide. The progesterone effect may involve inactivation or degradation of oxytocin receptors or activation of substances that are inhibitory to oxytocin binding. The effects of estradiol and progesterone on oxytocin receptor concentration in uterine explants are similar to those seen when the steroids are administered in vivo. The explant system, therefore, should prove useful in clarifying factors and processes that are involved in regulation of oxytocin receptor concentration in the uterus and in the initiation of parturition in the rat.

Animals↗
PubMed1981

Retinal vessel photocoagulation: a quantitative comparison of argon and krypton laser.

Retinal arteries of owl monkeys were photocoagulated with single exposures to argon laser green light (514 nm), krypton laser green light (531 nm), and krypton laser yellow light (568 nm). The distribution of damage along the vessel in different retinal layers was characterized geometrically after serial sectioning of the histopathologic material. Krypton laser radiation (green and, to an even greater extent, yellow) produced measurably greater effects on retinal vessels and adjacent structures than on deeper retinal levels; argon laser radiation (green) produced greater effects on the pigment epithelium. Krypton yellow produced the greatest total effect. The location of damage to the retinal arteries and pigment epithelium differed, with the peak of the damage around the arteries being farther from the optic disc than was the peak of the pigment epithelial damage.

Animals↗
PubMed1980

Purification and characterization of mammary myoepithelial and secretory cells from the lactating rat.

Myoepithelial and secretory cells from the mammary gland of the lactating rat have been isolated, purified, and characterized. Mammary tissue was dissociated with collagenase into basket-like networks of myoepithelial cells and single secretory cells. Because of their larger size, the myoepithelial cell networks could be separated from other mammary and blood cells by differential centrifugation. Isolated secretory cells were purified by isopycnic centrifugation in 25% bovine serum albumin. The purified myoepithelial and secretory cells were viable, as shown by the incorporation of 32P into distinct macromolecules that were separable by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Both myoepithelial and secretory cells retained their characteristic morphology after isolation and purification, as shown by light, transmission, and scanning electron microscopies. The isolated myoepithelial cells were unique and, thus, distinguishable from other mammary cells in a number of respects; they 1) contracted in response to the addition of oxytocin, 2) bound [3H]oxytocin specifically, 3) accounted for the content of alkaline phosphatase and [Na+ + K+]ATPase in mammary tissue, and 4) reacted specifically with antiserum prepared against purified myoepithelial cells. The purified secretory cells were unique in possessing glucose-6-phosphate dehydrogenase activity. The different cell markers not only gave independent estimates of the purity of the cell fractions, but they also may be helpful in identifying mammary cells in stages of differentiation and neoplastic transformation.

Adenosine Triphosphatases↗
PubMed1977

[On the photography of larger areas of the optic fundus-trials with the wide angle camera Clinitex CA-2 (author's transl)].

The wide angle fundus camera Clinitex CA-2 was tried out on patients and normal volunteers on evaluating the numerous photographs we found the three optic heads to deliver good results. The quality of the 60 degrees- and 100 degrees-pictures improved with the increasing dilatation of the pupil. Even retinal detachments and other changes with a different level were recoreded very well. In black-and-white- photography, uneven illumination of the fundus was successfully compensated by using a two-step developer with increased utilization of film speed. This procedure allowed good wide angle documentation of the fundus at comparatively low costs.

Color↗