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Biomedical subjects

D Mayer

Publications and source records attributed to D Mayer.

At least 253 records · Page 14Linked to original sources
PubMedDate not supplied

Sequential appearance and ultrastructure of amphophilic cell foci, adenomas, and carcinomas in the liver of male and female rats treated with dehydroepiandrosterone.

Dehydroepiandrosterone (DHEA), a hormone of the adrenal cortex, acts as a peroxisome proliferator and hepatocarcinogen in rats upon long-term treatment with high doses in the diet. The aim of the present study was to identify the site of origin of hepatocellular neoplasms and the sequence of preneoplastic lesions. Twenty-five female and 25 male rats were given 0.6% DHEA in the diet; 25 animals of each sex were controls. Groups of 5 treated and untreated animals were sacrificed after 4, 20, 32, 70, and 84 wk. Amphophilic cell foci were detected after 32 wk of treatment; they developed from the liver parenchyma almost exclusively in the vicinity of portal tracts. Adenomas of the amphophilic or amphophilic/tigroid cell phenotype were observed at 70 wk of treatment. Highly differentiated hepatocellular carcinomas presenting a similar cellular phenotype occurred after 70-84 wk. The incidence of hepatocellular carcinomas was 44% in female and 11% in male rats. Ultrastructural studies of the amphophilic cell foci and tumors revealed a marked proliferation of mitochondria and a moderate proliferation of peroxisomes in all lesions. In addition, a very strong peroxisome proliferation was observed in perivenular hepatocytes in the liver of female rats. Peroxisomes usually lacked core and showed flocculent matrices. In male rats, weak peroxisomal proliferation was observed. Typical morphological abnormalities of these peroxisomes were paracrystalline inclusions of striated appearance. Although the most prominent peroxisome proliferation was observed in perivenular hepatocytes, these cells did not seem to be involved in tumor development. In contrast, the morphological similarity of the amphophilic cell foci and the amphophilic/tigroid cell adenomas and carcinomas, their coincident localization near portal tracts, and the sequential appearance of these lesions suggest that the amphophilic cell foci represent an early stage in DHEA-induced hepatocellular neoplasia. Mitochondrial proliferation as the most prominent feature in all stages of this model of hepatocarcinogenesis may offer a new approach for analysis of hepatocarcinogenesis induced by DHEA and possibly other peroxisomal proliferators.

Adenoma↗
PubMedDate not supplied

Hospital design of the future--healing environments.

Predicting the future of hospital design is hardly a consensus forming art. Crystal ball visions of the 21st-century hospital vary from expert to expert. Perhaps that's simply a sign of the diversity of our health care system. Or perhaps it's a problem inherent in reading the future. For example, some hospital architects and facility planners say tomorrow's hospitals will be smaller due to technological advances. Others say those same advances will create larger hospitals brimming with high-tech equipment. Some say hospitals will be part of medical malls; others see them in a campus setting, perhaps accompanied by satellite facilities in the surrounding community. Yet, despite their often diverse views of the future, architects and planners do share common thoughts about hospital architecture in the decades ahead. Without question, they most commonly agree that hospitals will offer a more patient-friendly environment. Achieving that goal could take many forms, but it is expected to include the use of soothing colors, attractive landscaping, natural lighting, wayfinder lobbies and entrances, private rooms, quieter hallways and accommodations for family and friends.

California↗
PubMedDate not supplied

Florida Hospital.

Explore the source record for details and available documents.

Christianity↗
PubMedDate not supplied

Central hemodynamic effects of an oxytocin receptor antagonist (atosiban) in the isolated, perfused rat heart.

OBJECTIVE: Atosiban is a selective oxytocin receptor antagonist capable of inhibiting oxytocin-induced contractility of the uterus. Trials of this agent in intact animals and women as a tocolytic agent for preterm labor have shown atosiban to be devoid of cardiac effects. This is in contrast to other tocolytic agents, which have profound hemodynamic effects. We conducted this study to determine the cardiac effect of atosiban in the isolated, perfused rat heart model. METHODS: Hearts were excised from 60 female Sprague-Dawley rats and attached to a Langendorff apparatus. Left ventricular systolic pressure, heart rate, and contractility were measured. Hearts from half of the animals were exposed serially to 300 micrograms/min, 600 micrograms/min, and 1200 micrograms/min of atosiban. The remaining hearts formed the control group and were exposed to aerated Krebs solution. RESULTS: There were no significant differences between hearts exposed to atosiban and hearts within the control group for heart rate, left ventricular systolic pressure, and contractility. P values ranged from .12 to .73. CONCLUSIONS: Using a classic physiologic model to study cardiac performance and drug effects, we were unable to detect any central hemodynamic effects of atosiban. This is in contrast to oxytocin, which we previously studied and found negative chronotropic and positive ionotropic effects.

Animals↗
PubMedDate not supplied

Internet supply ordering. Helping medical group practices improve business operations.

Technology has opened the door to a new world of management tools in the physician practice environment. Productivity aids on the Web promise to alter forever the way we do everything--from interacting with vendors to caring for patients. Online medical, surgical and pharmaceutical supply acquisition sites, for example, already offer more efficient alternatives to phone and fax ordering, back-order challenges and supply cost monitoring. Not all sites are the same, however, and physicians and practice administrators must compare and contrast their needs with site offerings.

Cost Control↗
PubMedDate not supplied

Increase in NAD but not ATP and GTP concentrations in rat liver by dehydroepiandrosterone feeding.

Dehydroepiandrosterone (5-androsten-3beta-ol-17-one; DHEA), the main circulating steroid in humans, has been described to exert varied beneficial effects including antiobesity, anti-aging and anticancer action when used at pharmacological doses in experimental animals. To elucidate the mechanism of the pleiotropic effects of DHEA, we studied the effect of this steroid on concentrations of NAD and adenine and guanine nucleotides in rat liver. Administration of DHEA at 0.3% in the diet for 7 consecutive days caused an increase in liver NAD and NADP, but was without effect on NADH concentrations. This indicates a shift of the redox couple (NAD/NADH) towards oxidation in the DHEA-treated rats. Moreover, there was no change in adenine and guanine nucleotide concentrations, which disproves the hypothesis that the DHEA anticancer actions are due to a decrease in the availability of nucleosides for DNA synthesis. The findings indicate that an increase in liver NAD pool and/or altered redox status, but no changes in adenine or guanine nucleotide content, may be involved in the pleiotropic effects of DHEA.

Adenosine Triphosphate↗