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Biomedical subjects

L Bertók

Publications and source records attributed to L Bertók.

At least 73 records · Page 4Linked to original sources
PubMed1983

Bacterial modulation of the cellular immune response in mice. II. Stimulation by endotoxin of the reduced cellular immune response to LCM virus infection in aged mice.

Aging mice treated with radio-detoxified endotoxin and subsequently inoculated intracerebrally with lymphocytic choriomeningitis (LCM) virus died earlier and in a higher rate than the virus infected and otherwise untreated controls. Thus, in mice with insufficient T lymphocyte function due to aging, the radio-detoxified endotoxin pretreatment contributed to the outcome of LCM virus infection in the form of lethal meningitis. That indicates a stimulatory effect on the reduced cellular immunological reaction to the virus infection.

Age Factors↗
PubMed1983

Effect of irradiated haemophilus influenzae endotoxin preparations in mice.

A detoxified substance (rdLPS) was produced from Haemophilus influenzae endotoxin by ionizing radiation and its capacity to prevent attacks of dyspnoea elicited by endotoxin inhalation in mice has been studied. The rdLPS proved to be an effective stimulant of aspecific immune resistance of mice but it could only partly prevent attacks of dyspnoea.

Animals↗
PubMed1982

Radiodetoxified endotoxin induced lysosomal enzyme liberation and tolerance.

Beta-glucuronidase and cathepsin D activity was measured in rabbit sera. A significant increase in beta-glucuronidase activity was found following the intravenous application of a high dose of the parent endotoxin. The enzyme liberating effect of endotoxins irradiated by 50, 100, and 150 kGy was much weaker. Enzyme assays also confirmed that, independent of the irradiation, radiodetoxified endotoxins retain their endotoxin tolerance inducing effect.

Animals↗
PubMed1982

Effect of endotoxin and radio-detoxified endotoxin on cell membranes in vitro.

The effect of parent lipopolysaccharide (LPS) and radio-detoxified endotoxin (rdLPS) on various human blood cell membranes proved to be different as detected by 3H-concanavalin A-binding technique in vitro. The lectin-binding ability of erythrocyte membranes did not change upon treatment by either endotoxin, whereas that of lymphocytes was stimulated by LPS at 10-50 micrograms/ml concentration as well as by rdLPS at the lowest dose applied, i.e. 0.1 micrograms/ml. The LPS-treated platelets bound 3H-concanavalin A less than did the untreated controls; on the other hand, the rdLPS did not change the lectin-binding surface of these cells. The affection by radiation of cell membranes could be prevented by pretreatment with endotoxins. This fact, however, could not be considered a radioprotective effect. The micromorphological investigations by scanning electron microscopy (SEM) support our data concerning the functional alterations of plasma membranes of platelets and lymphocytes after LPS and rdLPS treatment as well as after the combined effect of endotoxin pretreatment and X-irradiation, since a severe smoothening of the cell surface could be observed.

Blood Platelets↗
PubMed1982

Effect of endotoxin preparations on the course of lymphocytic choriomeningitis virus infection in suckling mice.

Death occurred earlier and its rate was higher in suckling mice treated with parent or radio-detoxified endotoxin and subsequently inoculated intracerebrally with lymphocytic choriomeningitis (LCM) virus than in their virus infected but untreated control littermates. Thus, in suckling mice both the parent and the radio-detoxified endotoxin pretreatment contributed to the outcome of LCM virus infection in the form of lethal meningitis indicating its increasing effect on the cellular immunological reaction to the virus infection.

Animals↗
PubMed1982

Effect of ionizing radiation on chemical and biological properties of Salmonella minnesota R595 lipopolysaccharide.

Lipopolysaccharide of the Salmonella minnesota Re mutant R595 was irradiated with 60Co gamma doses of 50, 100, 150 and 200 kGy. The irradiated preparations were less toxic, less active in the Shwartzman reaction and as activators of the complement system, but they had retained the protection activity against the lethal action of endotoxin. The irradiation resulted in a dose-dependent decrease in the amounts of constituents (glucosamine, KDO, fatty acids) of the original lipopolysaccharide. With increasing irradiation doses increasing amounts of the irradiated material became dialysable (up to 21% in the 200 kGy sample). Only 50% of total fatty acids were present in the 200 kGy preparation compared to the parent lipopolysaccharide. The degradation products formed during irradiation have not been identified.

Animals↗
PubMed1981

[Protective effect on the liver through premedication with radiologically detoxicated endotoxin (Tolerin) in acute myocardial infarction in dogs].

An acute myocardial infarction was produced in experiments in dogs by ligature of the ramus anterior of the left coronary artery. Cell damages in the liver showed electron microscopically 90 and 120 minutes after the begin of the experiment. Destruction or disturbance in the permeability of the liver cells was not or slight developed by pretreatment with radiologically detoxicated endotoxin. In this case no aggravation of the liver function was evident parallel to the morphological changes and the ability of the liver to detoxication of endotoxin was reserved. The experiment shows that the protective effect of Tolerin which prevented the ischemic liver cell damage is not the endotoxin tolerance. The stabilizing effect to the lysosomal membrane by Tolerin is the cause likely.

Animals↗
PubMed1981

[Effect of pretreatment with radiation-detoxified endotoxin on endotoxin shock in dogs].

The protective action of the radiation detoxified endotoxin preparation (Tolerin) on the endotoxin shock of dogs was studied. Endotoxin shock was induced by the intravenous administration of 2 mg/kg of Escherichia coli endotoxin. It was found that the intraperitoneal administration of 4 mg of radiation-detoxified endotoxin (Tolerin) 48 hours prior to the inducement of shock prevents the drop in blood pressure and the decrease of cardiac output which promptly appear in the acute phase of endotoxin shock.

Animals↗
PubMed1980

The procoagulant activity of leukocytes pretreated with radiodetoxified endotoxin.

Rabbits were treated with Escherichia coli 089 endotoxin detoxified by ionizing irradiation (60 Co-gamma). The leukocytes (PMNs in 90%) obtained from rabbits that had been treated with the mother endotoxin elicited a well defined, those obtained from rabbits pretreated with detoxified endotoxin elicited a less pronounced, procoagulant activity. It is suggested that the procoagulant effect may play a part in the mechanism of the local Shwartzman phenomenon.

Animals↗
PubMed1979

Endotoxin tolerance in rats treated with antilymphocyte serum.

Rats were treated with rabbit anti-rat lymphocyte serum (ALS). The subsequent selective immunosuppressive effect on the immune response of thymus dependent antigen was shown by immunization with sheep red blood cells (SRBC). Endotoxin tolerance could be evoked in ALS treated animals. This suggests that the establishment of endotoxin tolerance is independent of thymus function and makes it possible to enhance the nonspecific resistance of immunosuppressed patients with a transplanted organ.

Animals↗
PubMed1978

Experiments on prevention of the endotoxin-abortifacient effect by radiodetoxified endotoxin pretreatment in rats.

Endotoxemia has been induced in pregnant rats by intravenous injection of 1 mg Escherichia coli endotoxin which resulted in intrauterine death and abortion of fetuses in 24 h. The abortifacient effect of endotoxin was prevented in 90% by 200 microgram radiodetoxified endotoxin, injected intravenously 24 h earlier. The authors suppose that the radiodetoxified endotoxin can be a good tool also in the prevention of human septic (endotoxin) shock in pregnancy.

Abortifacient Agents↗
PubMed1978

Haematologic effect and Shwartzman reactivity of radiodetoxified endotoxin.

Comparative experiments were made in rabbits with Escherichia coli O89 endotoxin and endotoxin detoxified by ionizing radiation (60Co-gamma, 5 Mrad). Radiation significantly weakened the leukopenia and thrombocytopenia provoking effect of endotoxin. Radiodetoxified endotoxin decreased the fibrinogen level only slightly and caused insignificant changes in reptilase time. The complement level was decreased less by the detoxified than by the parent endotoxin. Even the local Shwartzman phenomenon inducing capacity of radiodetoxified endotoxin decreased significantly, particularly when it was used for preparation and provocation, too.

Animals↗
PubMed1978

[Role of bacterial endotoxins in the tourniquet shock in rats].

By means of the lead acetate endotoxin sensitising method it was possible to demonstrate the development of endotoxaemia in tourniquet ischaemia of rats. The lethality of shock was greatly reduced by retreatment with radio-detoxified endotoxin (Tolerin). Prelinary liquidation of the Gram-negative enceroflora caused a similar reduction of lethality. On the basis of the results endotoxaemia of intestinal origin triggered by the vasoactive substances liberated during ischaemia and reaching the circulation are considered of importance in the pathogenesis of tourniquet shock.

Animals↗