Search PubMed⌕ Search

Biomedical subjects

C H Beck

Publications and source records attributed to C H Beck.

48 records · Page 3Linked to original sources
PubMed1972

The role of cell swelling in ischemic renal damage and the protective effect of hypertonic solute.

The failure of blood flow to return to the kidney following a transient period of ischemia has long been recognized. The cause of this "no-reflow" has been investigated in the rat after a transient period of total obstruction of the renal arteries. The vascular pattern of the kidneys as visualized with silicone rubber injection shows a diffuse patchy ischemia throughout the kidney, which persists after release of the obstructed renal artery. Electron microscopic studies of ischemic kidneys showed that all cellular elements were swollen and limiting the available vascular space. Functional studies revealed an increase in plasma urea nitrogen and creatinine after 1 hr or longer ischemic periods. The ischemia, cell swelling, "no-reflow," and subsequent renal dysfunction occurring after obstruction to the renal arteries were corrected by the administration of hypertonic mannitol, but were unaffected by an equivalent expansion of the extracellular fluid volume either with isotonic saline or isotonic mannitol, showing that the osmotic effect was primary. The hypothesis is presented that ischemic swelling of cells may occlude small blood vessels so that recirculation does not resume even after the initial cause of the ischemia is no longer present; solutes which do not penetrate cell membranes are able to shrink swollen cells, increase the available vascular space and thus permit reflow of blood to the ischemic organ.

Animals↗
PubMedDate not supplied

Chronic desipramine alters stress-induced behaviors and regional expression of the immediate early gene, c-fos.

This experiment examined the effects of acute or chronic administration of the antidepressant drug desipramine on conditioned stress-induced behaviors and regional c-fos expression in the brain. To this end, rats were exposed to three sequential daily sessions of uncontrollable foot-shock and matched, on the basis of crouching, into one of four groups. Two of these groups were exposed to saline injections twice daily and two were exposed to injections of desipramine (5 mg/kg, SC) twice per day, for 9 days. On the 10th day one of the saline groups received saline and the other received desipramine before being exposed to the shock chamber without shock. Likewise, on the 10th day one of the desipramine groups received saline and the other received desipramine before being exposed to the shock chamber without shock. Detailed behavioral analysis showed that compared to the saline-treated controls only the group treated chronically with desipramine, including on the test day, exhibited statistically significant reductions in crouching and increases in exploration during the test session. Similarly, Fos immunohistochemistry revealed that the chronic desipramine group showing positive behavioral effects was the only group in which there were significant reductions in the number of stress-induced Fos-positive neurons in five of 60 structures surveyed. These structures included the anterior cingulate cortex, anterior claustrum, central nucleus of the amygdala, dentate gyrus of the dorsal hippocampus, and paraventricular nucleus of the thalamus. To the extent that repeated exposure to uncontrollable stress is an animal model of depression, these and previous results suggest that these structures are potentially important neural targets for the antidepressant effects of desipramine.

Animals↗
PubMedDate not supplied

Rats treated chronically with the benzodiazepine, diazepam or with ethanol exhibit reduced variability of behavior.

The hypothesis that chronic treatment with diazepam or with ethanol reduces behavioral variability, was tested on rats in a radial maze. Eight groups (n = 6) of male Sprague-Dawley rats were given one of eight treatments of diazepam (0.0, 1.5, 3.0 or 6.0 mg/kg, IP, -30 min) or of 10% ethanol (0.0, 1.0, 1.5, or 2.0 g/kg, IP, -15 min) for 2 sessions of baseline and 18 sessions of acquisition. Each session consisted of 3 trials of 8 rewards each. Emptied food wells were immediately rebaited so that an entry into any arm produced a reward of 2 food pellets. Both diazepam and ethanol produced a dose-dependent reduction in the variability of arm choice, reduction in the variability of angle of turn between arms, and reduction in the variability of goal-directed behavior. Correlations between these measures suggested they were not independent. The implications of these reductions in behavioral variability for other effects of anxiolytic drugs are described.

Alcoholism↗