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Biomedical subjects

Y Cohen

Publications and source records attributed to Y Cohen.

At least 325 records · Page 18Linked to original sources
PubMed1985

Postirradiation soft tissue sarcoma occurring in breast cancer patients: report of seven cases and results of combination chemotherapy.

Seven cases of soft tissue sarcoma developing after primary or postoperative radiotherapy for breast carcinoma are reported. The sarcomas occurred within the irradiated volume, after a latent period of 4-26 years. These cases conform well to established criteria for the diagnosis of radiation-induced sarcoma. Chemotherapy, consisting of the four-drug combination CYVADIC (cyclophosphamide, vincristine, adriamycin, DTIC) was employed in six of the seven patients. Only two of them achieved partial remission, lasting only 2 and 3 months, respectively. The effectiveness of adriamycin-containing chemotherapy regimens in soft tissue sarcomas as well as the remote hazard of radiation-related sarcoma in primary or postoperative breast irradiation are discussed.

Adult↗
PubMed1985

Acute haemodynamic effects and tissue distribution of acebutolol in normotensive and spontaneously hypertensive rats.

Acute i.v. administration of 15 mg/kg acebutolol in normotensive (WKY), Okamoto (SHR) and Okamoto stroke-prone (SHR-SP) awake rats resulted in weak effects on blood pressure and in bradycardia more marked in SHR-SP. Thirty minutes after i.v. administration, lung and renal uptake of [14C]acebutolol was reduced in SHR compared to other rats. Muscle uptake was higher in SHR and blood concentration was higher in SHR-SP. Brain levels were low and similar in all rats. Plasma protein binding was identical in all rats. These results are discussed according to the characteristics of the three strains studied.

Acebutolol↗
PubMed1985

Cardiovascular effects of drugs acting on the autonomous nervous system, in awake, normotensive and hypertensive rats.

A study has been carried out in awake normotensive (WKY), spontaneously hypertensive (SHR) and renal hypertensive (RHR) rats in order to compare the reactivity of the autonomous nervous system using different indwelling catheterizations. In all cases, a jugular catheter was implanted for i.v. injections. The arterial cannula was implanted in the femoral artery (group 1) or in the right carotid artery (group 2), where the catheter was routed over 20 mm towards the heart, reaching the aortic arch. The plasma catecholamines levels were lower in the RHR than in the WKY or SHR, and whatever the strain, lower in group 2 than in group 1. In the WKY and the RHR, the mean blood pressure was higher in group 2 than in group 1. The tachycardia induced by isoprenaline and the pressor response to noradrenaline were higher in the SHR than in the WKY and in the RHR. By contrast, the reflex bradycardia was lower. Furthermore, the procedure of catheterization could modify the cardiovascular responses induced by adrenergic and cholinergic agents. These results demonstrate that indwelling catheterizations cannot be performed safely in the rat when studying effects on cardiac performance or vascular reactivity.

Acetylcholine↗
PubMed1985

Effects of tabernanthine on calcium and catecholamine stimulated contractions of isolated vascular and cardiac muscle.

The Iboga alkaloid tabernanthine (80 microM) non-competitively antagonized contractions in both the rat aorta and mesenteric artery induced by cumulative additions of noradrenaline and calcium. Tabernanthine (8, 40 and 80 microM) antagonized the K+ depolarization-induced contractions of the aorta. Tabernanthine (80 microM) depressed the phasic component of contractions induced by a single maximal concentration (10 microM) of noradrenaline in Ca++ -free solution. Tabernanthine induced a negative inotropic effect in electrically stimulated myocardial tissue and a negative chronotropic effect in the perfused rat heart. Tabernanthine is a calcium entry blocker which also affects cellular calcium metabolism.

Alkaloids↗
PubMed1984

Evidence for an activating effect of tabernanthine on rat brain catecholamine synthesis and elimination.

Tabernanthine increased the synthesis and elimination of catecholamines (CA) in the striatum and the rest of the brain, but not in the hypothalamus. These data provide evidence that tabernanthine may activate CA turnover of some brain structures by acting at 2 steps of the metabolic pathway. The results are discussed in relation to a central stimulating action and a hypoxia antagonistic effect of this drug.

Alkaloids↗
PubMed1984

Further studies on the treatment of advanced gastric cancer by 5-fluorouracil, Adriamycin (doxorubicin), and mitomycin C (modified FAM).

Twenty-two previously untreated patients with advanced gastric adenocarcinoma were treated with a modification of the original 5-fluorouracil, Adriamycin (doxorubicin), and mitomycin C (FAM) combination chemotherapy. The cycles were repeated every 6 weeks. There were four partial remissions and no complete response (overall response rate of 18%, with confidence interval of 0.02-0.34 for a confidence level of 95%). Duration of response ranged between 2.5 and 12 months. The overall median survival was 6.8 months. The median survival of responding patients (13.6 months) and the nonresponders (5.8 months) did not significantly differ. Sex and initial performance status did not influence the response to FAM. Toxicity was mild to moderate, and in only a few patients was it necessary to significantly reduce the drug doses or to prolong the intervals between treatments. Combining the current results with those obtained in a study recently reported the authors in which the original FAM was given to 33 evaluable patients, 11 responders have been seen among 55 consecutive patients with evaluable disease. These results are obviously inferior to those reported by other groups of investigators and led the authors to try another combination chemotherapy.

Adenocarcinoma↗
PubMed1984

The value of serum copper levels in non-Hodgkin's lymphoma.

A study of 306 serum copper levels (SCL) determinations in 115 patients with non-Hodgkin's lymphoma indicates a positive correlation between SCL and the state of disease. Patients with advanced disease (Stages II, III and IV) before treatment, those with active disease while under treatment, or in a relapse had a significantly higher SCL than patients in Stage I or those with no evidence of disease (NED). The mean SCL of patients with Stage I was similar to that of patients with NED. The mean values of these two groups did not differ significantly from that of healthy controls. Histological subtypes, according to the Rappaport classification, has no influence on SCL. Grouping into nodular versus diffuse lymphoma, histiocytic versus lymphocytic lymphoma and favorable versus unfavorable histology failed to demonstrate a difference between the groups. Within each subset a wide range of SCL was evident. However, good correlation was observed with the degree of disease activity. SCL may provide a useful parameter for patient monitoring. In this series, however, SCL was not useful for the prediction of an early relapse.

Adult↗
PubMed1984

Evidence for an antagonistic action of tabernanthine on hypoxia-induced changes in brain serotonin levels.

The effects of tabernanthine on serotonin (5-HT) levels were determined in several brain areas of rats exposed to various simulated altitudes (1800, 5200, 7000 m). The 5-HT synthesis inhibitor, para-chlorophenylalanine (PCPA), was used to dissociate the effects occurring at synthesis and release levels. Tabernanthine antagonized the decrease in hypothalamic 5-HT levels induced by a 7000 m hypoxia and also suppressed the decrease in PCPA-induced depletion observed at 5200 and 7000 m in the hypothalamus, the striatum and the rest of the brain. It was assumed that tabernanthine stimulates different steps of 5-HT metabolism. These effects, revealed by hypoxia, are related to other peripheral and central properties of this drug.

Alkaloids↗
PubMed1984

Fenfluramine and brain transmitters in the obese Zucker rat.

Genetically obese Zucker rats and their lean litter mates were treated for 5 days with fenfluramine. Levels of noradrenaline (NA), dopamine (DA), 5-hydroxytryptamine (5-HT) and gamma-aminobutyric acid (GABA) and their metabolism were assayed in the hypothalamus, striatum, medulla-oblongata pons and remainder of the brain. Fenfluramine induced a slight increase in the level of NE in the hypothalamus in lean rats and a marked decrease in obese rats. No change in the synthesis of NE was found. Fenfluramine had no effect on the level and metabolism of DA. The levels of 5-HT were decreased by fenfluramine in obese and lean rats, and the metabolism was increased. The levels of GABA were not changed by fenfluramine. Synthesis of GABA was increased in the remainder of the brain of obese and lean rats. These data suggest that fenfluramine acts on 5-HT systems in both obese and lean rats and are consistent with reports of the pharmacological effects of fenfluramine.

Animals↗
PubMed1984

Effects of physostigmine, paraoxon and soman on brain GABA level and metabolism.

The effects of sublethal doses of physostigmine, paraoxon and soman on GABA levels and metabolism were studied in small rat brain areas (hypothalamus, striatum, cerebellum, rest of the brain). Physostigmine induced a significant decrease in striatal GABA level and a reduction of synthesis index in the rest of the brain while organophosphates have little or no effect on GABA level and metabolism. This work provides new data about the physostigmine effect on brain GABA which could be related to the action of the anticholinesterase agents on other non-cholinergic neurotransmitters.

4-Aminobutyrate Transaminase↗
PubMed1984

The effects of a single dose and prolonged benzene administration on 5-hydroxytryptamine and 5-hydroxyindolacetic acid content in rat brain.

The contents of serotonin (5-HT) and its major metabolite, 5-hydroxyindolacetic acid (5-HIAA), in the hypothalamus, the striatum and the remainder of the brain, after a single dose and prolonged administration of benzene were studied in rats. Benzene was injected s.c. in doses of 1/20-1/5 LD50 for single administration and in doses of 1/80-1/20 LD50 daily six days a week during four weeks of prolonged administration. Single administration produced a decrease in the 5-HT content of the hypothalamus and striatum, accompanied by an increase of the 5-HIAA level in the striatum. The highest contents of both 5-HT and 5-HIAA in the hypothalamus and the striatum were seen 45 min after benzene injection and lasted for at least 180 min. After prolonged benzene administration increases of both 5-HT and 5-HIAA contents were observed, particularly with striatum. The accelerated 5-HT turnover in rat brain after acute and prolonged administration of benzene indicates an effect of the hydrocarbon on the metabolism of 5-HT.

Animals↗
PubMed1983

Effects of chronic beta-blocker treatment on catecholamine levels in spontaneously hypertensive rats.

In the present work the effects of a 55-day oral treatment with two beta-blocking agents (propranolol 40 mg/kg per day and S 2395 20 mg/kg per day) on the catecholamine (CA) content of central and peripheral structures were studied in spontaneously hypertensive rats (SHR). The concentrations of dopamine (DA), noradrenaline (NA) and adrenaline (A) in different structures dissected out from treated and control SHR were measured by a radioenzymatic method. At the peripheral level, no change in the concentration of NA (in the heart) or A (in the adrenal medulla) was observed. Propranolol increased the DA concentration in the C1 and C2 regions of the medulla oblongata and S 2395 increased the DA concentration only in the C2 region. In these two areas, the NA and A levels were unchanged. Both propranolol and S 2395 increased the DA, NA and A content in the locus coeruleus and in the anterior hypothalamus. On the contrary, there was no modification in the posterior hypothalamus. The anatomical specificity of these alterations of the CA levels suggests that they could be related to a specific action of beta-blockers on central catecholaminergic structures in SHR which might be linked to the antihypertensive effects of these drugs.

Adrenergic beta-Antagonists↗
PubMed1983

Effect of three anorectic drugs on brain GABA levels and synthesis in the Zucker rat.

1. Genetically obese Zucker rats and their lean littermates were submitted to a subchronic treatment with fenfluramine, mazindol and amphetamine. GABA levels and synthesis index were measured in different brain areas. 2. GABA levels, similar in obese and lean controls, were not changed after the three treatments. 3. A higher synthesis index of GABA was found in lean rats, in the striatum after mazindol and in the hypothalamus after amphetamine. 4. The three drugs increased the synthesis index of GABA in the remainder of the brain of both obese and lean rats.

Animals↗