Relationship between cell size, plasma cholesterol and rat adipocyte cholesterol storage

Organotypic cultures of newborn hamster choroid plexus were inoculated with equal titre doses of newly isolated or hamster adapted strains of mumps virus. The ultrastructure of virus replication in choroid epithelial cells of the cultures was compared. No qualitative differences were observed; however, the adapted strain produced significantly greater numbers of virions and earlier destruction of the cultures. These findings are consistent with previous in vivo observations of the ultrastructure of the replication of these strains in the newborn hamster central nervous system. This in vitro study leads further support to the hypothesis that differences in the in vivo biological effects of the virus strains are primarily the result of virus-cell rather than virus-host interactions.     

Radiation incidents with a cobalt-60 teletherapy unit

To separate fact from fiction regarding the susceptibility of women athletes to injury, three surveys were conducted. The initial data were collected from the athletic departments of collegiate institutions, and the final material was assembled from certified athletic trainers at these institutions, plus an extensive computer search of applicable publications. The collected statistical data were tabulated, and a written commentary was evaluated by the authors. It was established that injuries sustained by female athletes, aside from those related to different biological structures, were essentially no different than those of men, nor are well-trained women athletes more prone to injury. Ankle and knee injuries are most frequent, and women sustain many contusions, sprains, and shin splints. It is anticipated that the overall number of injuries will decrease as better coaches and trainers become available to women athletes.     

Analysis of three amphibian populations with quarter-century long time-series

Amphibians are in decline in many parts of the world. Long tme-series of amphibian populations are necessary to distinguish declines from the often strong fluctuations observed in natural populations. Time-series may also help to understand the causes of these declines. We analysed 23-28-year long time-series of the frog Rana temporaria. Only one of the three studied populations showed a negative trend which was probably caused by the introduction of fish. Two populations appeared to be density regulated. Rainfall had no obvious effect on the population fluctuations. Whereas long-term studies of amphibian populations are valuable to document population declines, most are too short to reveal those factors that govern population dynamics or cause amphibian populations to decline.     

Hypolipidemic activity of boronated nucleosides and nucleotides in rodents

Base-boronated nucleoside and phosphate-boronated nucleotides were potent hypolipidemic agents in rodents, lowering both serum cholesterol and triglyceride levels. Rat VLDL and LDL cholesterol levels were generally reduced and HDL cholesterol levels were significantly elevated after 14 days dosing at 8 mg/kg/day. Tissue cholesterol, triglyceride and phospholipid levels were reduced by selected derivatives. Increased fecal excretion of lipids did not appear to be a mechanism by which these derivatives lowered serum lipids in rodents. Rather, the agents suppressed appetite and reduced the activities of rate-limiting enzymes for de novo lipid synthesis, specifically cytoplasmic acetyl CoA synthetase, squalene synthetase, and phosphatidylate phosphohydrolase with IC50 values of approximately 10(-5) m.     

Effects of SR 141716A after acute or chronic cannabinoid administration in dogs

This study was undertaken to investigate the effects induced by the systemic administration of RB 101 [N-[(R,S)-2-benzyl-3[(S)(2-amino-4-methylthio)butyl dithio]-1-oxoprpyl]-L-phenylalanine benzyl ester], a mixed inhibitor of the enkephalin catabolism able to cross the blood-brain barrier, in antinociception produced by adrenal medullary tissue transplanted in the rat spinal subarachnoid space. For this purpose, the antinociceptive responses induced by intravenous (i.v.) administration of RB 101 were evaluated in the tail-flick in rats transplanted 28 and 56 days before the test. Systemic administration of RB 101 induced antinociceptive effects in sham-operated rats, as previously reported. RB 101 also enhanced significantly the antinociception produced by the autotransplant 28 and 56 days after surgery. The antinociceptive responses of RB 101 in both sham-operated and autotransplanted rats were blocked by naloxone, but were not modified by the noradrenergic antagonist, phentolamine, suggesting a selective involvement of opioid mechanisms. The present results indicate that the inhibitors of enkephalin catabolism enhance the antinociception induced by adrenal medullary transplants.     

Heat-induced alterations in embryonic cytoskeletal and stress proteins precede somite malformations in rat embryos

Previous work from this laboratory has demonstrated that heat exposure on gestation day 10 (GD10) resulted in disrupted somite development 24 hr after exposure and subsequent thoracic skeletal malformations in neonates. The purpose of the present study was to examine the effects of in vitro heat shock on de novo protein synthesis and on cytoskeletal protein levels in developing rat embryos. Explanted GD10 embryos were exposed to temperatures of 42-42.5 degrees C for 15 min. At various times postexposure (0-27 hr). embryos were labeled with 35S-methionine and processed for sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) separation. Transient enhanced de novo synthesis of 70- and 90-kD proteins was observed 1-8 hr after exposure. The 70-kD protein was identified as a eukaryotic stress protein and the presence of this protein was detected between 2 and 27 hr posttreatment. Western blot analysis was used to detect quantitative changes in total actin (microfilaments), tubulin (microtubules), and vimentin (intermediate filaments). Immediately following exposure, a reduction of total vimentin to minimal detectable levels was observed in heat-treated embryos. Levels of total vimentin remained depressed for more than 2 hr and gradually returned to control levels 4-8 hr postexposure. No change in total actin or tubulin was detected in treated embryos. The data demonstrate that heat-induced alterations in proteins comprising intermediate filaments occur concomitantly with the induction of stress proteins and precede aberrant somite morphology. These alterations in embryonic proteins may help elucidate the mechanism(s) by which skeletal malformations are produced.