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Biomedical subjects

J Feldman

Publications and source records attributed to J Feldman.

At least 271 records · Page 15Linked to original sources
PubMed1977

[Variations in the effect of clonidine on arterial pressure in rats in the presence of various anesthetics].

The central hypotensive agent, clonidine (30 microgram/kg i.v.) has been injected in normotensive rats anesthetized with various agents. This dose of clonidine elicits usually a biphasic blood pressure response, i.e. a transient increase due to peripheral vasoconstriction, followed by a long lasting decrease. This has been observed in the animals anesthetized with pentobarbitone as well as with urethane. The hypotensive effect is abolished during chloralose, ketamine or Alfatésine anesthesia. These data emphasize that some anesthetics mays particularly modify the effects of centrally acting cardiovascular drugs.

Alfaxalone Alfadolone Mixture↗
PubMed1976

Cobalt(III) affinity-labeled aspartokinase. Formation of substrate and inhibitor adducts.

The kinase active site of the aspartokinase-homoserine dehydrogenase enzyme complex of Excherichia coli has been affinity labeled both with substrates aspartate and adenosine triphosphate and feedback inhibitor threonine. Co(III) exchange-inert adducts of aspartokinase and inhibitor or substrates were produced in situ by oxidation of Co(II) with H2O2. Emzyme-Co(III)-adenosine 5'-triphosphate (ATP), enzyme-Co(III)-aspartate, and enzyme-Co(III)-threonine ternary adducts were produced in this manner. The formation of the enzyme-Co(III)-threonine adduct leads us to conclude that threonine inhibits the kinase activity of this enzyme complex by binding in the first coordination sphere of the catalytic metal ion cofactor, a conclusion which is consistent with evidence derived from previous nuclear magnetic resonance data obtained in this laboratory. The quaternary adducts formed by H2O2 oxidation in the presence of aspartokinase, Co(II), ATP, aspartate, and threonine comprised a mixture of both ezyme-Co(III)-ATP-aspartate and enzyme-Co(III)-ATP-threonine adducts. The formation of the quaternary aspartate-containing adduct was unexpected, since the presence of threonine was expected to prevent access of the aspartate to the active site; most significantly however, the the sum of the numbers of aspartate plus threonine molecules incorporated per active site is one. We believe that this shows direct steric overlap between the metal-adjacent binding sites for aspartate and threonine. Aspartate or threonine can not occupy the kinase active site simultaneously; this conclusion is consistent with the direct competitive inhibition of aspartate by threonine observed in steady-state kinetic studies.

Adenosine Triphosphate↗
PubMed1976

Analysis of patient disability after curative resection for colonic and rectal cancer.

Ninety-seven patients undergoing curative resection for colonic or rectal cancer were investigated to determine the degree of early disability, that is, disability one to four years postoperatively. Seventy per cent of the patients were disability free postoperatively and fully employable, and among those who died of the disease, 73 per cent had no disability three months prior to death. The results indicate that waiting five years to determine cure in this disease wastes many man-years of fruitful employability.

Adult↗
PubMed1976

Modification of adrenal function by the anti-serotonin agent cyproheptadine.

The effect of the serotonin antagonist, cyproheptadine (Cypro), on metyrapone-induced stimulation of the pituitary-adrenal axis was evaluated in nine normal subjects. The subjects underwent standard oral metyrapone tests (750 mg every four h, for six doses) while taking no medications and while receiving oral Cypro (4 mg every six h). Cypro administration caused a significant reduction in: 1) baseline 17-hydroxycorticosteroid (17-OH) excretion (-31 +/- 7.2%), 2) the increase above baseline in 24 h 17-OH excretion on the day after metyrapone (-32 +/- 4.9%), 3) serum 11-deoxycortisol concentrations 8 h (-45 +/- 5.5%) and 24 h (-18 +/- 3.6%) after the first dose of metyrapone, and 4) plasma ACTH concentration 8 h (-32 +/- 8.2%) and 24 h (-22 +/- 8.0%) after the first dose of metyrapone. When compared with the control test, Cypro administration did not alter: 1) baseline 17-ketosteroid secretion, 2) the fall in serum cortisol concentration while taking metyrapone, 3) the serum free metyrapone concentration, 4) cortisol metabolism, 5) the adrenal response to ACTH, and 6) assay methods for measurement of serum and urinary corticosteroids. Our data suggest that Cypro can reduce pituitary-adrenal responsiveness by reducing plasma ACTH concentrations. If Cypro acts as a serotonin antagonist, our data lends support to the idea that serotoninergic mechanisms are important in the control of pituitary ACTH secretion in normal human subjects.

17-Hydroxycorticosteroids↗
PubMed1975

Role of the ventral surface of the brain stem in the hypotensive action of clonidine.

The areas S of the ventral surface of the brain stem and the immediately surrounding zone were superficially destroyed by the means of electro-coagulation, in 14 cats. This destruction produced a drop in blood pressure, which was transient in 9 and definitive in 4 animals; in one cat only the arterial pressure did not change after the destruction. In 6 animals which have been sham-operated, clonidine (15 mug/kg, i.v.) always induced a marked fall in blood pressure whereas in 10 animals which had maintained or recovered a normal blood pressure after the destruction of the area S, clonidine (15 mug/kg) injected intravenously no longer produced any decrease of the arterial pressure. These results suggest that the integrity of the areas S is necessary for the development of the hypotensive action of clonidine. This hypotensive drug may act, at least at the level of the ventral surface of the brain stem, through inhibition of a vasopressive structure.

Animals↗
PubMed1975

Bladder outlet obstruction caused by vaginal fibromyoma: the female prostate.

Three patients with urinary difficulty were cured by surgical removal of a viaginal fibromyoma. The appearance of this benign tumor on an intravenous cystogram and cystoscopy as well as the clinical response to surgical removal bears similarity to the hypertrophied prostate in men. The best surgical technique for its removal is enucleation via a vaginal incision.

Adult↗
PubMed1975

[Role of ventral surface of brain stem in control of arterial pressure and in hypotensive action of clonidine].

Superficial destructions of the brain stem have been performed in cats at the level of the chemosensitive areas "S". These destructions produced a drop in blood pressure, which was transient in 9 and definitive in 4 animals. In 6 sham-operated animals, clonidine (15 mug/kg), injected intravenously, always induced a marked fall in blood pressure, whereas in the 10 animals which have maintained or regained normal blood pressure after the destruction of the areas S, clonidine no longer induced any decrease in blood pressure. These results suggest that the integrity of the areas S is necessary for the development of the hypotensive action of clonidine. This hypotensive drug may act, at least at that level of the ventral surface of the brain stem, through an inhibition of a vasopressive structure.

Animals↗