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Biomedical subjects

G Zbinden

Publications and source records attributed to G Zbinden.

At least 109 records · Page 6Linked to original sources
PubMed1978

Granuloma pouch assay. I. Induction of ouabain resistance by MNNG in vivo.

Growth of granulation tissue was induced in rats inside a subcutaneous air pouch by injection of croton oil. Granulation tissue, isolated and cultured in vitro, gave satisfactory and reproducible cloning efficiency of fibroblast-like cells. This experimental model system was used to study the induction of autosomal point mutations in vivo leading to ouabain resistance. For this purpose the mutagen MNNG was administered in the granuloma pouch, and the formation of ouabain-resistant clones was determined in vitro. Various application schedules, expression times in vivo and selective conditions in vitro were evaluated. The highest frequencies of ouabain-resistant clones were found when MNNG was injected into the pouch 24--48 h after induction of granulation tissue, followed by an expression time in vivo of 24--48 h. No ouabain-resistant clones were formed by cells isolated from untreated rats or from animals receiving the highest tolerated doses of MNNG per os or by intraperitoneal injection. The potential usefulness of the granuloma pouch assay for the evaluation of mutagenic and carcinogenic substances in vivo is discussed.

Animals↗
PubMed1978

Biochemical effects of gum arabic, gum tragacanth, methylcellulose and carboxymethylcellulose-Na in rat heart and liver.

Repeated oral administration of commonly used suspending media, gum arabic, gum tragacanth, methylcellulose, and carboxymethylcellulose-Na to rats caused uncoupling of oxidative phosphorylation in liver and heart mitochondria and partial inhibition of mixed function oxidases of liver endoplasmic reticulum, as measured by 2-biphenylhydroxylation and 4-biphenylhydroxylation. There were considerable differences between the compounds with regard to potency and reversibility of these effects. Only methylcellulose at a concentration of 0.5% did not alter mitochondrial function and mixed function oxidases. It is recommended as suspending medium for the use in pharmacological and toxicological experiments.

Acacia↗
PubMed1978

Model systems for cardiotoxic effects of anthracyclines.

The use of anthracycline antibiotics in cancer chemotherapy is limited by their cardiotoxic qualities. For the evaluation of new derivatives animal model systems are required. Cardiomyopathy can be induced in rabbits and monkeys, but these models are too expensive for screening purposes. In rats, anthracycline antibiotics cause morphologic lesions of the heart muscle, but these are more difficult to demonstrate than in larger animals. However, significant changes of the heart function (electrocardiogram (ECG), cardiac output), the function of heart mitochondria (inhibition of electron transfer, uncoupling of oxidative phosphorylation and inhibition of Ca translocation) occur in a dose-related manner. Intraventricular conduction defect demonstrated in the ECG is one of the earliest and most consistent expressions of the cardiotoxic properties of anthracyclines. It was therefore used as primary screening parameter. The results of the screening of over 50 new anthracyclines has shown that the cardiotoxic properties vary considerably and that they are not closely related to the chemotherapeutic and the hematotoxic properties. Interesting structure-activity relationships were observed in a series of rubidazone derivatives substituted at the benzhydrazone part of the molecule.

Animals↗
PubMed1977

Modification of adriamycin toxicity in rats fed a high fat diet.

Rats fed a diet containing a high percentage of butter, cholesterol, cholic acid and proply thiouracil (HFD) showed weight loss and developed hyperlipidemia, marked fatty infiltration of the liver, moderate elevation of SGPT, degenerative changes of the heart muscle, bradycardia, alterations of the QRS complex in the electrocardiogram, and initial hemoconcentration followed by moderate anemia. Treatment with adriamycin (18 X 1 mg/kg i.p.) resulted in significant augmentation of the cardiotoxic effects of this drug demonstrated by electrocardiographic measurements and myocardial histopathology. Adriamycin-induced atrophy of the lymphatic tissue was seen only in rats fed HFD and not in animals receiving ground chow. Adriamycin levels in the heart after single i.p. injection were higher in rats receiving HFD. This effect was present already after 10 days on HFD. At this time histopathological liver changes were present and SGPT was elevated. It is concluded that the increase in adriamycin toxicity is, at least in part, due to diminished excretion by the liver. These experimental findings are in accordance with clinical observations which have identified liver disease as one of the important risk factors for the development of adriamycin cardiomyopathy.

Alanine Transaminase↗
PubMed1977

Toxicological evaluation of imipramine in combination with adriamycin and strophanthin.

Chronic oral administration of imipramine to rats caused characteristic changes of the electrocardiogram (ECG), i.e. prolongation of the PR interval, widening of the QRS complex, and increase in T-wave voltage. The cardiotoxic anthracycline antibiotic adriamycin induced dose-dependent widening of the QRS complex. This effect on intraventricular conduction was not enhanced in rats receiving both drugs. The high adriamycin dose (5 x 4 mg/kg) abolished imipramine-induced prolongation of the PR interval and T-wave elevation. This was not seen with the low adriamycin dose (20 x 1 mg/kg). Imipramine prolonged survival time of rats treated with toxic doses of adriamycin, but enhanced growth retardation in animals receiving the low adriamycin dose. Chronic treatment with increasing doses of strophanthin induced significant flattening of the T wave in rats with and without imipramine therapy, but did not influence the changes of the ECG or body weight gain caused by imipramine. It is concluded that the combined use of imipramine and adriamycin or strophanthin did not lead to a serious enhancement of the toxicity of the tricyclic antidepressant.

Animals↗
PubMed1977

A simplified method for the isolation of sperm heads from the caput epididymidis of rodents and from ejaculated rabbit seminal plasma.

The present report describes a simple and rapid procedure to isolate highly purified sperm heads from mouse, rat and rabbit. The isolation procedure involves mincing of the caput epididymidis (CPE) of mice and rats to obtain a crude CPE suspension. This suspension is filtered to remove tubular fragments. The filtrate containing sperms and cellular contaminants is trypsinized, followed by sonication. To obtain rabbit sperm head suspension, ejaculated spermatozoa are briefly exposed to the cationic detergent CTAB-D, followed by trypsinization. Trypsin treatment of the suspension yields sperm heads and tails. The suspension containing sperm heads and tails is separated by discontinuous sucrose density gradient centrifugation. Highly purified and enriched sperm heads are recovered from the bottom of 2.5 M sucrose of the gradient. Enriched sperm heads contain less than 1% sperm tails.

Animals↗
PubMed1977

Circulating platelet aggregates and thrombocytopenia induced by intravenous infusions of arachidonic and lauric acids in guinea pigs.

Slow intravenous infusion of Na laurate (NaL) into guinea pigs caused a rapid appearance of platelet aggregates in the arterial blood and a precipitous fall in platelet counts. During the infusion of Na arachidonate (NaA) thrombocytopenia developed slowly, and few and smaller platelet aggregates appeared in the arterial blood. Considerably more guinea pigs died during or after the NaA infusion than after administration of NaL. The possibility that arachidonic acid and other long-chain fatty acids may play a role in the development of thrombosis and thromboembolism is discussed.

Animals↗
PubMed1976

Palmitic acid-1-14C incorporation and turnover in lung phospholipids of rats treated with chlorphentermine, RMI 10.393 and Ro 4-4318.

The effects of 3 lipidosis-inducing drugs on the incorporation and turnover of palmitic acid-1-14C in lung phospholipids was studied. In rats treated with 1 dose of chlorphentermine or RMI 10.393, the incorporation of palmitate-1-14C into most lung phospholipid fractions was moderately decreased, but markedly lowered after 1 dose of Ro 4-4318. Eight doses of chlorphentermine and RMI 10.393 strongly inhibited the incorporation of palmitate-1-14C into lung phospholipids, whereas with 8 doses of Ro 4-4318 the incorporation was highly increased. Thirty hours after the last of 3 injections of the labeled palmitic acid the turnover of most lung phospholipids was considerably lower in chlorphentermine- and RMI 10.393-treated rats than in controls. Ro 4-4318, however, induced a highly increased turnover of most phospholipids. After 54 h, this effect had practically disappeared. Our studies showed that phospholipid storage after treatment with chlorphentermine and RMI 10.393 is mainly due to decreased degradation of phospholipids, whereas increased synthesis accounts for the effect of Ro 4-4318.

Amitriptyline↗
PubMed1975

Effects of seven anthracycline antibiotics on electrocardiogram and mitochondrial function of rat hearts.

Daunomycin, adriamycin and 5 semisynthetic anthracycline antibiotics inhibited oxygen consumption or ATP production of rat heart mitochondria in vitro. The no-effect levels varied depending on the substrate used and ranged from 1 nmole per mg mitochondrial protein. Mitochondrial functions were also studied in hearts of rats treated with repeated i.p. injections of the 7 antibiotics. Decrease in oxygen consumption without change in ATP production was observed with adriamycin and NSC-149584. Daunomycin, NSC-164011, NSC-143496 NSC-143114 affected primarily ATP production. The most potent compounds were daunomycin and adriamycin which damaged mitochondrial function at cummulative doses of approximately 10 mg/kg. ECGs were monitored in groups of equally treated rats. Cardiotoxicity manifested itself by progressive widening of the QRS complex often followed by the development of a S-wave trough. The most toxic compounds also induced intraventricular block, bradycardia and heart failure. The development of the ECG changes showed a good correlation with the impairment of mitochondrial function.

Adenosine Triphosphate↗