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Biomedical subjects

B Tóth

Publications and source records attributed to B Tóth.

At least 55 records · Page 3Linked to original sources
PubMed1986

Hormonal regulation of phosphorylase phosphatase activity in rat liver.

The effect of glucagon and insulin on rat liver phosphorylase phosphatase activity in vivo was investigated. The activity of phosphatase was found to decrease following the administration of glucagon and increase with insulin in a reversible manner. No change was detected in the activity of heat-stable phosphatase inhibitors in the hormone-treated samples. Liver protein kinases (regulatory subunit of cAMP-dependent protein kinase and/or Ca2+-dependent phosphorylase kinase) are suggested to regulate the activity of hepatic phosphorylase phosphatase (type 1 and 2A).

Animals↗
PubMed1986

Regulatory subunit of type II cAMP-dependent protein kinase as substrate and inhibitor of protein phosphatase-1 and -2A.

The dissociated regulatory subunit (RII) of autophosphorylated cAMP-dependent protein kinase II was dephosphorylated by the catalytic subunits of protein phosphatase-1 and -2A (phosphatase-1c and -2Ac) and by a high-Mr polycation-dependent form of phosphatase-2A (2Ao) with Km values of 5, 0.3 and 1 microM, respectively. Dissociation of protein kinase by cAMP preferentially increased the dephosphorylation of RII by phosphatase-1c, whereas polycations (histone Hl or polybrene) markedly stimulated phosphatase-2Ac and -2Ao even in the absence of cAMP. Thiophosphorylated RII inhibited the dephosphorylation of phosphorylase a by these phosphatases with half-maximum inhibitory concentrations of 0.1-0.36 microM.

Animals↗
PubMed1985

Effect of fructose 1-phosphate on the activation of liver glycogen synthase.

The activation (dephosphorylation) of glycogen synthase and the inactivation (dephosphorylation) of phosphorylase in rat liver extracts on the administration of fructose were examined. The lag in the conversion of synthase b into a was cancelled, owing to the accumulation of fructose 1-phosphate. A decrease in the rate of dephosphorylation of phosphorylase a was also observed. The latency re-appeared in gel-filtered liver extracts. Similar latency was demonstrated in extracts from glucagon-treated rats. Addition of fructose 1-phosphate to the extract was able to abolish the latency, and the activation of glycogen synthase and the inactivation of phosphorylase occurred simultaneously. Fructose 1-phosphate increased the activity of glycogen synthase b measured in the presence of 0.2-0.4 mM-glucose 6-phosphate. According to kinetic investigations, fructose 1-phosphate increased the affinity of synthase b for its substrate, UDP-glucose. The accumulation of fructose 1-phosphate resulted in glycogen synthesis in the liver by inducing the enzymic activity of glycogen synthase b in the presence of glucose 6-phosphate in vivo and by promoting the activation of glycogen synthase.

Animals↗
PubMed1983

Heterotropic interactions of AMP and glucose binding sites in phosphorylase a are destroyed by limited proteolysis.

Subtilisin BPN' hydrolyses a single peptide bond in phosphorylase a. The two proteolytic fragments are attached to each other by noncovalent bonds in solution as shown by gel filtration and ultracentrifugation studies. The subtilisin nicked phosphorylase a is inactive, however, still binds AMP and glucose as judged by equilibrium dialysis and fluorescence experiments. The modified enzyme can be dephosphorylated by protein phosphatase and AMP is an effective inhibitor of the dephosphorylation reaction. Glucose cannot cancel the AMP inhibition as well as cannot expel AMP from the nucleotide binding site. Thus a single nick in the polypeptide chain breaks the "communication" between the two ligand binding domains.

Adenosine Monophosphate↗
PubMed1983

Limited proteolysis of glycogen phosphorylase a by subtilisin BPN'.

The limited proteolysis of rabbit skeletal muscle phosphorylase a was undertaken with subtilisin BPN' immobilized to Sepharose 4B. The effect of substrates, activators and inhibitors of phosphorylase a was investigated by monitoring the changes in phosphorylase activity in the SDS gel electrophoretic pattern and in the 32P-content of 32P-labeled phosphorylase a. Phosphorylase a loses its activity upon subtilisin treatment. All ligands tested protect phosphorylase a activity against subtilisin action, probably by inducing structural changes in the tower loop of the enzyme. Glucose-6-P significantly accelerates [32P]peptide release from phosphorylase a through altering the structure of the N-terminal tail segment. The two subunits of dimeric phosphorylase a are held together by strong interactions--deduced from the correlation of the rate of proteolysis and the disappearance of catalytic activity.

Adenosine Monophosphate↗
PubMed1982

Interaction of ligands in phosphorylase A as monitored by crosslinking and enzymatic modifications: synergism of glucose and caffeine manifested in the exposure of N-terminal segment.

1. Glycogen, caffeine and glucose dissociate phosphorylase a tetramer to dimers with half-maximum effect at 0.16%, 1.1 and 71 mM concentration, respectively, as monitored by crosslinking with dimethyl suberimidate at 18 degrees C. 2. The above ligands increase the rate of dephosphorylation and tryptic digestion of phosphorylase alpha at 18 degrees C in the same way with half-maximum effect at 0.04%, 0.1 and 9 mM concentration, respectively. 3. Caffeine and glucose acted synergistically in tetramer dissociation as well as in the enzymic modifications. 4. The alpha-anomer of D-glucose was twice as effective as its mutarotational equilibrium solution.

Animals↗
PubMed1979

[Effect of indications and pre-existing conditions on the result of McDonald's cervix-closure surgery].

Authors have performed the McDonald cerclage operation on 172 gravidae because of cervical incompetence. From these pregnancies 80.2 per cent of the infants have survived over the sixth day. While with operations performed on the basis of extended indications for surgery an effect of 56.5 per cent was achieved, it was in cases of classical ones 92.8 per cent. Two complicated cases are reported caused by blastospores or bacteria respectively, isolated also in the vaginal secretion which have ascended into the uterine cavity. Both cases resulted in fetal death and in a septic condition of the mother. It is emphasized that the normal vaginal bioflora is essential condition for the cervical suture.

Candida albicans↗
PubMed1978

[Effectiveness of Canesten preparations in blastomycoses of the female genitalia].

According to the examinations of the authors the administration of Canesten vaginal tablets for treatment of vulvovaginitis caused by blastospores resulted in 81% of the cases in a lasting healing, in cases with an affected anamnesis in 75%. With additional treatments of Canesten solution and cream administration the efficiency was further increased and thus results of 90% or 76%, respectively could be achieved. With sanitation of auto- and heteroinfectious foci the recurrences of fungal infections could be avoided. There had been no teratogeneous effects in the newborns following Canesten treatment in pregnants. In course of Clotrimazol administration general characteristic side effects were not observed, a slight and quickly passing inflammation occured in few cases.

Blastomyces↗
PubMed1978

Oddi's sphincter spasm in hypocalcaemia of dogs.

1. Decreases of serum calcium concentration in dogs lead to increased basal tone of Oddi's sphincter in the employed experimental model. 2. This effect is independent of the agent used for decreasing the serum calcium level. 3. Spasmolysis was observed immediately after the injection of CaCl2. CaCl2 alone, however, had no effect in "normocalcaemic" animals. 4. Local decrease of calcium level plays no significant role in the sphincter spasm. It is suggested that the spasm is elicited by increased smooth muscle excitability as a consequence of the hypocalcaemic state prevailing in the body.

Ampulla of Vater↗
PubMed1975

[Therapeutic results achieved through the advantage of a combination of oral metronidazole and vaginal natamycin tablets in urogenital protozoan, trichobacterial and blastomyces infections].

Vaginal inflammations caused by Trichomonas, Leptothrix vaginalis or Candida and other less common organisms respectively, were treated very successfully with a combination of metronidazole orally and a natamycin preparation vaginally (Pimafucin vaginal tablets). In women with urogenital Trichomoniasis a cure was obtained in 96,1% of the cases (microbiologically controlled); Candida mycoses of the vagina were cured clinically in 89% of the cases after the first course of treatment and mycologically in 79% of the cases. Of special importance is the rapid and successful elimination of the mixed infection before birth, because this diminishes perinatal morbidity of the fetus. The combination treatment of bilateral, constantly interchanging Candida and Trichomonas infections of the vagina is of importance to both sexes, especially with respect to the elimination of sterility. From the onco-gynecological point of view the combination treatment with metronidazole and natamycin appeared to be of value as it limits the incidence of dyskariosis of the epithelial cells, which occur frequently in cases of inflammation of the vagina or cervix uteri. No teratogenic effect was observed with this combination when applied during pregnancy.

Administration, Oral↗