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S Postius

Publications and source records attributed to S Postius.

32 records · Page 2Linked to original sources
PubMed1984

[Synthesis and H2-antihistaminic effect of N,N'-bisheteroaryl N,N'-bisheteroaryl-substituted cyanoguanidines and 2-nitro-1,1-ethenediamines. 17. H2-antihistaminics].

In studies on structure-activity relationships of histamine H2-receptor antagonists, cyanoguanidines and 2-nitro-1,1-ethendiamines, which contain the heterocyclic rings of ranitidine and cimetidine twofold, were prepared and tested for their H2-antihistaminic activity on the isolated guinea-pig atrium and on the histamine stimulated acid secretion of the anaesthetized rat. While the N,N'-disubstituted keten-N,N-acetales 8 and 11 possess markedly stronger H2-antagonistic activity than Ranitidine, the analogously substituted cyanoguanidines 3b and 6 proved to be as effective as the reference substance. The substances 3a and 13, with unsubstituted C-5 position of one heterocyclus, showed lower potency.

Animals↗
PubMed1984

The effect of different histamine H2-receptor antagonists on the gastric acid secretion of the isolated whole stomach of the mouse and on the heart rate of spontaneously beating atrium of the guinea-pig.

The effect of metiamide, cimetidine and 2-[2-[5-(dimethylaminomethyl)furan-2-ylmethylthio]ethylamino]- 5-(6-methylpyrid-3-ylmethyl)-pyrimidin-4-one (SK & F 93 479) was studied on the acid secretion of the isolated stomach of the mouse and on the heart rate of the right atrium of the guinea-pig. The order of potency of histamine H2-antagonists investigated was identical on atrium and stomach, however, the pA2 values obtained on acid secretion were approximately 10 times lower than those found on atrium.

Animals↗
PubMed1984

Evidence for thimerosal induced cytoprotection on rat stomach.

Intragastrically administered thimerosal protects against ethanol induced ulceration with an ID50 of 1.6 mg/kg body weight. In contrast, intravenously administered thimerosal exhibits an ID50 of greater than 30 mg/kg. The antiulcerogenic effect of thimerosal persists for at least 20 hours before allowing gastric ulcers to be induced by ethanol. Intragastric application of thimerosal protects against acetyl salicylic acid induced with an ID50 of 6.8 mg/kg. Stress ulceration is inhibited by thimerosal with an ID50 of 9.2 mg/kg body weight. Investigations on the structure-activity relationship show that it is the mercury moiety and not the thiosalicylic acid moiety which is responsible for the inhibition by thimerosal.

Animals↗
PubMed1983

Evidence for a functional cytoprotective effect produced by antacids in the rat stomach.

The fall in potential difference evoked by taurocholate was diminished after exposure of the gastric mucosa of rats to aluminium-containing antacids. Other parameters of barrier disruption (H+ back diffusion, Na+ influx) exhibited the same pattern and correlated with the change in potential difference. This cytoprotective-like effect was abolished in animals pretreated with indomethacin. Taurocholate significantly diminished the PGE2 content in the gastric mucosa and its release into the instillate. The PGE2 content of gastric mucosa and instillate of animals pretreated with an aluminium-containing antacid was not decreased after exposure to taurocholate.

Animals↗
PubMed1983

Prostaglandin content in the rat gastric mucosa during healing of chronic ulcers induced by acetic acid.

Non-steroidal anti-inflammatory compounds delayed the regeneration of chronic gastric ulcers induced by acetic acid in the rat. The delayed regeneration was connected with a decreased PGE2 content in the proliferating tissue. Glucocorticoid influenced neither the regeneration of mucosal damages nor the gastric PGE2 content. The carboanhydrase inhibitor, acetazolamide, also did not alter the restoration of gastric mucosa after being damaged. From the clinical point of view, the safe use of NOSAC will be emphasized in patients with ulcer anamnese. The findings with prednisolone did not confirm a similar safe use of this drug in patients.

Acetates↗
PubMed1983

In vivo rat bladder: a new model to screen spasmolytic compounds.

A model for in vivo screening of spasmolytic compounds of the rat urinary bladder has been developed. It is physiological, specific, and adaptable. A filling volume of the bladder of 0.6-1 ml proved to be optimal. Agonists such as acetylcholine, KCl and BaCl2 exerted almost identical spasmogenic effects on both the in vivo and the in vitro model (isolated rat bladder strip). Moreover, the antagonistic effects of atropine, N-butylscopolammonium bromide, or flavoxate hydrochloride were directly comparable between the two models. Intravenously administered atropine was shown to be effective immediately; after intragastric application the maximum effect can not be observed until after 9 min. The in vivo rat bladder model presented is proposed to be a suitable method for advanced screening of spasmolytic compounds to include their absorption, biotransformation, and excretion.

Acetylcholine↗
PubMed1982

Influence of nonsteroidal anti-inflammatory compounds on healing of chronic gastric ulcers in rats.

Pre-treatment with NOSAC led to an increase of ulcer index in a dose-dependent manner indicating the aggravation of gastric lesions under the influence of NOSAC. The severity of mucosal lesions was diminished by lengthening the time between the last day of pre-treatment with NOSAC and the day on which ulcers were induced. When NOSAC were administered after the induction of gastric ulcers, the healing of the latter was significantly delayed.

Animals↗
PubMed1978

Anaerobiosis and oxygen recovery: changes in cell cycle distribution of Ehrlich ascites tumor cells grown in vitro.

The cell cycle distribution of in vitro cultured Ehrlich ascites tumor (EAT) cells was analysed by pulse-cytophotometry to characterize the growth cessation observed under anaerobic conditions. DNA histograms provided evidence that in the absence of oxygen EAT cells accumulate in the G1 and early S phase of the cell cycle while in the presence of oxygen an increase in G2 was observed during 24h culture period. Cellular recovery from anaerobiosis was observed soon after transfer of the cells into fresh aerobic culture medium but occurred slowly if the cells were only resupplied with air. Cell cycle analyses as well as (14C)-thymidine incorporation suggest considerable synchronization results from the introduction of anaerobiosis.

Anaerobiosis↗
PubMedDate not supplied

Multiple effects of amobarbital on Ehrlich ascites tumor cells. Inhibition of pyruvate dehydrogenase.

The inhibition of the proliferation of hyperdiploid Ehrlich ascites tumor cells in suspension cultures by amobarbital is coupled to an increased glycolytic activity as shown by lactic acid production and glucose consumption; higher concentrations of amobarbital than 1 mM enhance the ATP/ADP ratio of the total cell. The actual activity of pyruvate dehydrogenase of intact cells is completely inhibited in the presence of 2 mM amobarbital as was shown by the 14CO2 evolution from [114C]pyruvate or the incorporation of 14CO2 into the total lipid fraction of the cells from [U-14C]lactate. The pyruvate dehydrogenase complex from Ehrlich ascites tumor cells is completely inhibited by 1 mM amobarbital in vitro. The activity of alpha-oxoglutarate dehydrogenase is inhibited by amobarbital, too, as well as shown by measuring the 14CO2 evolution from [1-14C]glutamate with intact cells. It is suggested that the inhibition of pyruvate dehydrogenase in the presence of amobarbital is the result of a direct action on the enzyme as well as the consequence of a change in the cellular redox state or its energy charge.

Adenosine Diphosphate↗
PubMedDate not supplied

Proliferation and metabolic activities of Ehrlich ascites tumor cells in chemically defined albumin media.

Cell proliferation, viability, DNA-, RNA-, protein synthesis, amino acid transport, repiration and lactate/glucose quotient of Ehrlich ascites tumor cells grown in suspension culture in serum free medium supplemented with albumin charges of different origin were studied. Optimal cell growth was obtained in nutrient medium supplemented with 1% bovine serum albumin (Cohn-fraction V, Serva). Cell proliferation under these culture conditions was delayed to 50% as compared to controls in normal medium; the rate of synthesis of macromolecules was reduced; energy metabolism was not significantly imparied. The trend of the cells in albumin medium to attach to glass was independent from the pH of the cultures between 7.2 and 8.0; it was enhanced by fatty acid deprivation of the albumin.

Amino Acids↗
PubMedDate not supplied

Cell proliferation and metabolism of Ehrlich ascites tumor cells grown in chemically defined albumin medium for several passages.

Cell proliferation, cell cycle distribution, viability, uptake of alpha-aminoisobutytic acid, cyclo leucine and 2-deoxyglucose as well as DNA, RNA and protein synthesis of Ehrlich ascites tumor cells grown in suspension culture over three passages in serum free nutrient medium supplemented with 1-2% bovine serum albumin) Cohn fraction V, Serva) were measured and compared to cells grown in medium supplemented with 15% horse serum. At the end of the fourth passage in vitro, that is the third passage in serum free albumin medium, the growth of the cells is reduced to about 10% of the controls, accumulation of the cells in G2 is delayed and the number of dead cells rises to 30%. The transport rates of alpha-aminoisobutyric acid and of 2-deoxyglucose slowly decrease while the uptake of cycloleucine shows a more complex behaviour in albumin medium. Incorporation of thymidine and leucine into the cells corresponds to the growth rate, while the incorporation of uridine in normal as well as in albumin medium exhibits different pattern. The present experiments demonstrate, that it may be possible to preserve this cells in a fairly "physiological" state during two passages in albumin medium.

Aminoisobutyric Acids↗
PubMedDate not supplied

Proliferation kinetics and metabolic features of in vitro grown Ehrlich ascites tumor cells in the presence of exogenous pyruvate.

The proliferation of in vitro grown Ehrlich ascites tumor cells is inhibited by pyruvate concentrations greater than 2 mM. In the presence of 4-5 mM pyruvate the growth is reduced to about 50%, in the presence of 20 mM to about 5-10%. Viability of the cells is not severely affected. Increase of DNA corresponds to the cell growth. On recultivation in pyruvate free standard medium, growth is nearly normal. Flow cytometric analyses of the proliferation kinetics of the cells in the presence of 20 mM pyruvate revealed a retardation of the passage of all phases of the cell cycle. No phase specific effects could be detected though the S- and G2M-phase are more afflicted than G1. The growth inhibition of EAT cells by pyruvate seems to depend on the presence of glucose. Exogenous pyruvate (greater than 1-2 mM) causes an activation of pyruvate dehydrogenase, a reduction of lactate production from glucose and a stimulation of lipid biosynthesis; the NAD/NADH ratio of the cells is reduced and a rise of glycolytic intermediates beyond glyceraldehyde-3-phosphate dehydrogenase is observed. Maximal activation of pyruvate dehydrogenase by non toxic concentrations of dichloroacetate is also accompanied by an inhibition of cell growth. It is suggested that an increase of glyceraldehyde-3-phosphate level and the changes in the redox state of the cells are of relevance for the inhibition of cell growth by pyruvate. 100-500 microM exogenous glyceraldehyde-3-phosphate strongly inhibited cell growth.

Animals↗
PubMedDate not supplied

Titration of rat liver with digitonin: a well defined short term damage of cellular metabolism.

Carefully performed pulse titration of the isolated rat live in the course of continuous erythrocyte free perfusion with small amounts of digitonin causes a short term permeability of liver cell plasma membranes with concomitant short lived release of intracellular low or high molecular compounds such as ATP or lactate dehydrogenase. Gluconeogenesis from lactate being completely inhibited during this period restores within about one minute up to a level that depends on the amount of perfused digitonin. The described experimental model is suggested to be useful for the measurement of cytoplasmic metabolites under physiological conditions. It moreover offers the possibility to import foreign substances into liver cells that normally do not penetrate liver cell plasma membranes.

Adenosine Triphosphate↗