The epidermal growth factor (EGF) receptor is present in the mouse placenta in both a low- and a high-affinity form having approximate values for Ka of 10(7) M-1 and 10(9) M-1, respectively. No significant difference (P greater than or equal to 0.05) in the number of receptors existed between placental membrane preparations from days 10 and 17, both for the low- and the high-affinity receptor. The number of both high- and low-affinity receptors was significantly lower (P less than 0.05) for day 14 placental membranes than for either day 10 or day 17 placental membranes. Cross-linking of 125I-EGF to placental membranes resulted in the specific labelling of two major receptor forms with approximate molecular weights of 170,000 and 154,000, as determined by sodium dodecyl sulphate-polyacrylamide gel electrophoresis.

Animals↗

PubMedDate not supplied

Visual arrestin in Limulus is phosphorylated at multiple sites in the light and in the dark.

Arrestins participate in the termination of phototransduction in both vertebrates and invertebrates. However, the visual arrestins of invertebrates and vertebrates differ significantly from one another in that the invertebrate visual arrestins become phosphorylated rapidly in response to light while those in the photoreceptors of vertebrates do not. In an effort to understand the functional relevance of arrestin phosphorylation, we examined this process in the photoreceptors of the horseshoe crab Limulus polyphemus. We report that Limulus visual arrestin can be phosphorylated at three sites near its C-terminus and show that arrestin molecules phosphorylated on one, two, and three sites are normally present in both light- and dark-adapted photoreceptors. Light adaptation increases the amount of arrestin phosphorylated at three sites.

Adaptation, Ocular↗

PubMedDate not supplied

Quantitation of glandular gastric changes in rats given a proton pump inhibitor for 3 months with emphasis on sampling scheme selection.

Proton pump inhibitors and H2-receptor antagonists suppress gastric acid secretion and secondarily induce hypergastrinemia. Sustained hypergastrinemia has a trophic effect on stomach fundic mucosa, including enterochromaffin-like (ECL) cell hypertrophy and hyperplasia. Histomorphometric quantitation of the pharmacologic gastric effects was conducted on 10 male and 10 female rats treated orally with LY307640 sodium, a proton pump inhibitor, at daily doses of 25, 60, 130, or 300 mg/kg for 3 mo. Histologic sections of glandular stomach, stained for chromogranin A, were evaluated by image analysis to determine stomach mucosal thickness, mucosal and nonmucosal (submucosa and muscularis) area, gastric glandular area, ECL cell number/area and cross-sectional area. Total mucosal and nonmucosal tissue volumes per animal were derived from glandular stomach volumetric and area data. Daily oral doses of compound LY307640 sodium caused slight to moderate dose-related mucosal hypertrophy and ECL cell hypertrophy and hyperplasia in all treatment groups as compared with controls. All observed effects were prominent in both sexes but were generally greater in females. The morphometric sampling schemes were explored to optimize the data collection efficiency for future studies. A comparison between the sampling schemes used in this study and alternative schemes was conducted by estimating the probability of detecting a specific percentage of change between the male control and high-dose groups based on Tukey's trend test. The sampling scheme analysis indicated that mucosal thickness and mass had been oversampled. ECL cell density quantitation efficiency would have been increased by sampling the basal mucosa only for short-term studies. The ECL cell size sampling scheme was deemed appropriate for this type of study.

2-Pyridinylmethylsulfinylbenzimidazoles↗

PubMedDate not supplied