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Biomedical subjects

T Balazs

Publications and source records attributed to T Balazs.

At least 73 records · Page 4Linked to original sources
PubMed1981

Divergent effects of propranolol and furosemide pretreatment on acute cardiomyopathy induced by minoxidil in beagle dogs.

Previous studies have shown that oral administration of minoxidil on 2 consecutive days produces an increase in heart rate and myocardial necrosis in Beagle dogs. Propranolol treatment (1.0 or 3.0 mg/kg every 8 h) did not abolish tachycardia and did not alter the incidence or severity of minoxidil-induced necrosis. In the present studies, pretreatment with either furosenmide (10 mg/kg) or hydrochlorothiazide (250 mg/kg) reduced serum potassium levels. However, only furosemide (for 11 days) reduced significantly the incidence of minoxidil-induced necrosis; only 2 of 10 animals (20%) developed myocardial lesions compared to 11 of 14 (79%) in the non-treated group. The incidence and severity of lesions in hearts from animals treated with furosemide for 3 days or hydrochlorothiazide for 11 days were essentially the same as in animals given minoxidil alone. Thus, furosemide, under certain conditions, can reduce the incidence of acute ventricular lesions induced by minoxidil.

Animals↗
PubMed1981

Muscular degeneration in rats after postnatal treatment with 6-mercaptopurine.

6-Mercaptopurine monohydrate was injected sc at 2 mg base/kg/day from 2 to 22 days of age to four litters of rat pups (four females, four males per litter). Control neonates were injected sc with basic saline (pH 8). Daily observations for signs of toxicity were made during the treatment period and once weekly thereafter until the rats were 6 months of age. The pups were weighed at 2, 12, 23, 34, 100, and 480 days of age. Fertility was tested at 3 to 6 months of age. From 6 months of age on, the rats were examined for tumors at 3-month intervals until the experiment was terminated at 16 months of age. A reduction in body weight of treated rats began between 34 and 100 days of age and became more pronounced by 16 months of age. Fertility was similar in treated and control groups and there were no detectable tumors in either group. The major finding in treated rats was a delayed onset of hind leg paresis that was first detected at 12 months of age. Light microscopic examination of tissues taken from the hind quarters of these rats at 16 months of age revealed a severe atrophic degeneration with fatty infiltration of sublumbar and thigh muscles.

Animals↗
PubMed1980

Age-dependent sensitivity of the rat to neurotoxic effects of streptomycin.

Streptomycin sulfate (300 mg/kg s.c.) was injected for various periods into preweanling rats and for 3 weeks into weanling rats. Beginning at 8 days of age, body movement and hearing were examined for 6 and up to 17 weeks, respectively. Abnormal movements and deafness occurred only in rats treated during the preweaning period; within this period the greatest sensitivities for these abnormalities occurred from 2 to 11-17 and 5 to 11 days of age, respectively, indicating that the cochlea is more sensitive to streptomycin than the site (vestibular or central) responsible for the dyskinesias.

Age Factors↗
PubMed1980

Detection of dopaminergic supersensitivity induced by neuroleptic drugs in mice.

We investigated the sensitivity of dopaminergic receptors in mice fed neuroleptic drugs. Groups of mice were fed daily doses of approximately 10% of the LD50 of haloperidol, clozapine, chlorpromazine, trifluoperazine, or thioridazine for 2, 4, or 8 weeks. Four days after withdrawal of the neuroleptics, thozalinone, a dopaminergic stimulant, was given ip at 50 mg/kg to elicit gnawing behavior. Increased gnawing behavior was seen in mice after 4 weeks of administration of haloperidol (80%), chlorpromazine (80%), trifluoperazine (100%), and thioridazine (100%) compared with control values (50%). The gnawing behavior in mice treated with clozapine was the same as that for control mice. Levels of gnawing behavior after 2 or 8 weeks of administration of the same drugs were lower than those reported above. Alcohol increased the thozalinone-elicited gnawing behavior 2 weeks after dosing with haloperidol and trifluoperazine. After 4 and 8 weeks of administration of the drugs, the locomotor activity of mice was increased from 29-113% (4 weeks) to 37-110% (8 weeks) compared with controls. The study of neuroleptic drug-induced dopaminergic supersensitivity may serve as a method for detection of tardive dyskinesia-inducing effects.

Animals↗
PubMed1979

Hemoglobin Crete (beta 129 ala leads to pro): a new high-affinity variant interacting with beta o -and delta beta o -thalassemia.

Hemoglobin Crete, beta129 (h7)ala leads to pro, is a new mutant hemoglobin (Hb) with high oxygen affinity that was discovered in a Greek family in various combinations with beta- and deltabeta-thalassemia. The propositus, who presented an unusual clinical picture of an "overcompensated" hemolytic state, with erythrocytosis, splenomegaly, abnormal red cell morphology, and marked erythroid hyperplasia, appeared doubly heterozygous for Hb Crete and deltabeta-thalassemia. His red cells contained 67% Hb Crete and 30% Hb F, and the combination of these two hemoglobins resulted in a blood P50O2 of 11.2 mm Hg. A brother with Hb Crete trait (38% Hb Crete, 56% Hb A, blood P50O2 23.0 mm Hg) did not have significant erythrocytosis. Purified Hb Crete was heat-unstable and exhibited a high oxygen affinity, and a normal Bohr effect. We postulate that the beta 129 proline substitution disrupts the H helix, perturbing nearby residues involved in alpha 1 beta 1 contact sites of the Hb tetramer.

Adult↗
PubMed1979

Decreased aminotransferase activity of serum and various tissues in the rat after cefazolin treatment.

Treatment of rats with cefazolin in vivo significantly suppressed activity of alanine and aspartate aminotransferases in serum and in the liver, brain, kidney, and heart. Simultaneous administration of pyridoxal further reduced enzyme activity except in the liver, where there was no change. Pyridoxal 5'-phosphate partly reversed the decreased enzyme activity in the serum, liver, and kidney, but did not return it to the amount observed in the control animals; enzyme activity remained suppressed in the brain and heart. The effect of cefazolin was dose related, but there was no sex-related difference. In contrast to its action on am-notransferase activity, cefazolin elicited no effect on alkaline phosphatase (pyridoxal-5'-phosphate hydrolase) in serum or on pyruvate carboxylase in the liver, heart, and kidney. Cefazolin exposed to the hepatic microsomal mixed-function oxidase system in vitro was partly converted into metabolites that inhibited serum alanine aminotransferase activity in vitro. The latter inhibition was reversed by the addition of pyridoxal 5'-phosphate.

Alanine Transaminase↗
PubMed1978

Comparison of effects of quinidine and dihydroquinidine on canine heart.

Various cardiac effects of quinidine and dihydroquinidine were tested in isolated dog hearts and in vivo in dogs. No significant differences were found in the negative inotropic, chronotropic, and dromotropic effects. Dihydroquinidine was more potent than quinidine in decreasing coronary arterial pressure.

Animals↗
PubMed1978

Conditioned avoidance responses of young mice and offspring of mice treated with neuroleptic or mutagenic agents.

Conditioned avoidance response (CAR) tests were used to determine the effects of perinatal exposure to three neuroleptic drugs and an antineoplastic agent in mice. In one experiment, mice were given sc injections of haloperidol at 1.25 mg/kg.d or trifluoperazine at 12.5 mg/kg.d for 2 wk, starting when they were 4 d old. In additional groups, nursing dams were given haloperidol at 5 mg/kg.d or trifluoperazine at 25 mg/kg.d for 2 wk during lactation. CAR tests were begun when offspring were 40 d of age. No statistically significant evidence of impairment in the learning ability of any group was found. In a second experiment, hybrid male mice were treated with a single ip injection of triflupromazine at 50 mg/kg or triethylenemelamine at 0.2 mg/kg and were mated 2, 4, and 6 wk after dosing. The male offspring were tested for learning ability at 40 d of age. No statistically significant differences in CAR values were observed in offspring of triflupromazine-treated males. CAR values of offspring of triethylenemelamine-treated males mated 4 wk after dosing were significantly higher than those of controls.

Animals↗
PubMed1978

Cardiac lesions induced by chemicals.

Chemically induced cardiomyopathies are frequently the consequences of a cardiac metabolic imbalance brought about by exaggerated functional affects. The infarctlike lesions induced by adrenergic beta-receptor stimulants and the vasodilating antihypertensives serve as examples of this phenomenon. Direct cardiotoxic mechanisms not related to cardiovascular functional effects are responsible for another class of toxic cardiomyopathy. An example of this is the cardiomyopathy produced by the anthracycline antineoplastic agents. The pathogenesis, morphological changes and toxicologic features of these cardiomyopathies are described with particular reference to their detection in preclinical toxicity studies.

Acute Disease↗
PubMed1977

Effect of 2-chloroethanol on hepatic microsomal enzymes in the rat.

The effect of 2-chloroethanol on the activities of hepatic microsomal enzymes in the rat has been studied. A significant reduction in activities of drug-metabolizing enzymes (aminopyrine N-demethylase, coumarin 3-hydroxylase) and a marked decrease of glucose 6-phosphatase were seen in both sexes given dose levels of 20 mg/kg sc daily for 7 days. Inosine diphosphatase activity remained unaltered. In male rats given 3 or 10 mg/kg, a trend in the inhibition of drug metabolism was found. A single dose of 50 mg/kg caused no apparent change in the activities of the enzymes measured.

Animals↗