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I Farkas

Publications and source records attributed to I Farkas.

At least 37 records · Page 2Linked to original sources
PubMed1991

Two glycogen synthase isoforms in Saccharomyces cerevisiae are coded by distinct genes that are differentially controlled.

In previous work, we identified a Saccharomyces cerevisiae glycogen synthase gene, GSY1, which codes for an 85-kDa polypeptide present in purified yeast glycogen synthase (Farkas, I., Hardy, T.A., DePaoli-Roach, A.A., and Roach, P.J. (1990) J. Biol. Chem. 265, 20879-20886). We have now cloned another gene, GSY2, which encodes a second S. cerevisiae glycogen synthase. The GSY2 sequence predicts a protein of 704 residues, molecular weight 79,963, with 80% identity to the protein encoded by GSY1. Amino acid sequences obtained from a second polypeptide of 77 kDa present in yeast glycogen synthase preparations matched those predicted by GSY2. GSY1 resides on chromosome VI, and GSY2 is located on chromosome XII. Disruption of the GSY1 gene produced a strain retaining about 85% of wild type glycogen synthase activity at stationary phase, while disruption of the GSY2 gene yielded a strain with only about 10% of wild type enzyme activity. The level of glycogen synthase activity in yeast cells disrupted for GSY1 increased in stationary phase, whereas the activity remained at a constant low level in cells disrupted for GSY2. Disruption of both genes resulted in a viable haploid that totally lacked glycogen synthase activity and was defective in glycogen deposition. In conclusion, yeast expresses two forms of glycogen synthase with activity levels that behave differently in the growth cycle. The GSY2 gene product appears to be the predominant glycogen synthase with activity linked to nutrient depletion.

Amino Acid Sequence↗
PubMed1991

Cholecystokinin promotes sleep and reduces food intake in diabetic rats.

It has been reported that systemic injections of cholecystokinin (CCK) elicit the behavioral characteristics of satiety, including sleep, in rats. CCK is a potent stimulator of insulin secretion, and insulin is hypothesized to be involved in sleep and feeding regulation. The purpose of the current experiments was to study the possible role of endogenous insulin in the food-intake-reducing and hypnogenic effects of intraperitoneally (IP) administered CCK. Normal and streptozotocin (STR)-diabetic rats were injected with isotonic saline or CCK (10 and 50 micrograms/kg) at dark onset, and sleep-wake activity was determined for the next 12 h. There were no significant differences between the baseline sleep-wake activity of normal and diabetic rats. IP injection of CCK elicited a selective increase in nonrapid-eye-movement sleep in both groups during the first postinjection hour. In a separate experiment, the effects of CCK (10 micrograms/kg) on food intake were determined in control and diabetic rats; CCK suppressed the 1-h food intake in both groups. In a third experiment, the effects of CCK treatment (50 micrograms/kg) on plasma insulin levels were determined. In normal rats, CCK elicited a two-fold increase in plasma insulin concentration, whereas diabetic rats had a significantly lower basal insulin level which was not affected by CCK treatment. We conclude that hypnogenic and food-intake-reducing effects of exogenously administered CCK are closely associated; however, pancreatic insulin does not play a significant role in either of these effects.

Animals↗
PubMed1991

Glycogen metabolism and signal transduction in mammals and yeast.

Mammalian glycogen synthase, with its complex multisite phosphorylation mechanisms, continues to provide interesting and novel examples of the regulation of protein function. The mammalian enzyme is phosphorylated in a hierarchal manner such that modification of certain sites requires the prior phosphorylation of other sites. Yeast contains two glycogen synthases that have extensive similarities to their mammalian counterpart but the greatest divergence in amino acid sequence is seen precisely in the regions likely to be involved in covalent control. We hope that examination of the control of the yeast glycogen synthase will be as informative as study of the mammalian enzymes, whether by revealing important parallels with the mammalian system or by uncovering major differences in mechanism.

Amino Acid Sequence↗
PubMed1990

Isolation of the GSY1 gene encoding yeast glycogen synthase and evidence for the existence of a second gene.

Glycogen synthase preparations from Saccharomyces cerevisiae contained two polypeptides of molecular weights 85,000 and 77,000. Oligonucleotides based on protein sequence were utilized to clone a S. cerevisiae glycogen synthase gene, GSY1. The gene would encode a protein of 707 residues, molecular mass 80,501 daltons, with 50% overall identity to mammalian muscle glycogen synthases. The amino-terminal sequence obtained from the 85,000-dalton species matched the NH2 terminus predicted by the GSY1 sequence. Disruption of the GSY1 gene resulted in a viable haploid with glycogen synthase activity, and purification of glycogen synthase from this mutant strain resulted in an enzyme that contained the 77,000-dalton polypeptide. Southern hybridization of genomic DNA using the GSY1 coding sequence as a probe revealed a second weakly hybridizing fragment, present also in the strain with the GSY1 gene disrupted. However, the sequences of several tryptic peptides derived from the 77,000-dalton polypeptide were identical or similar to the sequence predicted by the GSY1 gene. The data are explained if S. cerevisiae has two glycogen synthase genes encoding proteins with significant sequence similarity The protein sequence predicted by the GSY1 gene lacks the extreme NH2-terminal phosphorylation sites of the mammalian enzymes. The COOH-terminal phosphorylated region of the mammalian enzyme over-all displayed low identity to the yeast COOH terminus, but there was homology in the region of the mammalian phosphorylation sites 3 and 4. Three potential cyclic AMP-dependent protein kinase sites are located in this region of the yeast enzyme. The region of glycogen synthase likely to be involved in covalent regulation are thus more variable than the catalytic center of the molecule.

Amino Acid Sequence↗
PubMed1990

[Secretin versus cimetidine in the therapy of active bleeding from peptic gastroduodenal lesions. A prospective, randomized, double-blind, multicentric study].

In a multicentric, prospective, double-blind, randomized trial 101 patients with active bleeding (Forrest, Type 1/b) from gastroduodenal ulcers or erosions were treated with secretin (n = 50, dose: 800 clinic units/24 hours) or cimetidine (n = 51, dose: 75 mg/hour). The bleeding and the effect of the therapy were endoscopically confirmed. The bleeding was stopped during 48 hours of treatment in 36 patients of the secretin treated group and in 25 of the cimetidine treated group (p less than 0.05). In 72 hours the control of bleeding was established in a total of 75 patients (41 secretin, 34 cimetidine; not significant). Surgery was necessary in 7 vs. 9 cases. The mortality was 1 vs. 4 cases. The mean transfusion requirements were 6.6 units in secretin- and 8.2 units in cimetidine treated group (p less than 0.01). There was no difference in rebleeding rate. The results show a trend in favour of secretin compared to cimetidine in the treatment of active bleeding from gastroduodenal ulcers or erosions.

Adolescent↗
PubMed1990

Phosphorylase phosphatase activities of rat liver in streptozotocin-diabetes.

Protein phosphatase-1 and 2A, accounting for all the hepatic activity regulating phosphorylase, were assayed in streptozotocin-induced (8 weeks) diabetic Wistar rats. Cytosolic protein phosphatase-1 and 2A were distinguished by chromatography on heparin-Sepharose and by inhibition with inhibitor-2. Approx. 25-35% increases in type-1 phosphorylase phosphatase activity measured in cytosols were registered in diabetic rats when compared with control and 24 h fasting animals. The enrichment of protein phosphatase-1 in the cytosol of streptozotocin-treated rat livers could not be attributed to the reduced glycogen content with the onset of diabetes, since this elevated level of type-1 phosphatase was not observed in fasting rats with low glycogen content. The translocation of type-1 phosphatase from the particulate fraction into the cytosol was also recorded in trypsin-treated samples of diabetic rat livers. The apparent molecular weight of type-1 phosphatase in the cytosol of control and fasted rats was 160,000 as judged by gel filtration. The type-1 phosphatase activity that was released from the particulate fraction by streptozotocin-induced diabetes identified a further enzyme species (Mr 110,000) in the cytosol. Our data imply that the higher levels of cytosolic protein phosphatase-1 in diabetic rat liver could be a consequence of the dissociation of the catalytic subunit of protein phosphatase-1 and the glycogen-binding subunit in rat livers.

Animals↗
PubMed1990

[Ultrasound-guided percutaneous antegrade wirsungography in chronic calcifying pancreatitis].

Dilated pancreatic duct was found by ultrasonography in a patient in association with the characteristic sonographic features of chronic calcifying pancreatitis. Endoscopic retrograde pancreatography showed an obstruction of the Wirsung's duct 3 cm far from the papilla of Vater. Further parts of the duct could not be opacified by this manner. However, visualisation of the rest of the pancreatic duct was successfully performed by ultrasonically guided antegrade wirsungography making the preoperative planning of the suitable type of surgery possible. Beside the case history the importance of the is method is also discussed in diagnosis of pancreatic diseases.

Calcinosis↗
PubMed1990

Electron probe microanalysis of human teeth for the determination of individual age.

The calcium and phosphorus weight concentrations as well as the calcium/phosphorus weight ratio were determined by electron probe microanalysis both peritubularly and intertubularly in the dentine of 25 adults of varying age and sex, originating from our autopsy material. The studies were performed with a TESLA BS-300 scanning electron microscope coupled with an EDAX-149-10 X-ray detector and a BMG-38100 X-ray analyser with an accelerating potential of 15 kV, a sample current of 100 pA and a measurement time of 20 s. Peritubularly the Ca/P weight ratio of the hypermineralized part of the dentine decreases with age and is in close correlation with it (r = -0.9052) and this tendency is significant even at the level of 95% (P less than 0.05). The equation of the regression line is: Y = 37.17 x +139.37 where x is the age and y is the Ca/P weight ratio. The weight concentration of phosphorus is in an even closer correlation with age (r = 0.9712) and this correlation is also significant (P less than 0.01). The equation of the regression line is the following: y = 625.0 x -42.06 The close correlation of both the Ca/P weight ratio of the teeth and of the phosphorus weight concentration with the age allows individual age determination to be performed in the course of forensic medical and palaeoanthropological studies.

Age Determination by Teeth↗
PubMed1990

[The diagnostic value of so-called "post-cholecystectomy bile duct dilatation"].

In 1706 gallstone operations the diameter of the common bile ducts was determined in 990 cases during telecholangiography using a so-called functional cholangiodiametry. The data of 213 postoperative determinations of the common bile duct diameters performed during the follow-up period did not support the existence of a postcholecystectomic compensatoric dilation of the common bile duct. Ultrasound and ERCP failed to find postoperative bile duct dilation in patients without complaints following cholecystectomy and in persons with complaints of extrabiliary origin. In conclusion we found that biliopancreatic and organic reasons (residual calculi, papillary stenosis, bile duct stenosis, chronic pancreatitis) can always be detected as the underlying cause of a significant bile duct dilation.

Cholangiography↗
PubMed1989

Activation/dephosphorylation of muscle glycogen synthase phosphorylated by phosphorylase kinase.

1. Glycogen synthase from rabbit skeletal muscle was phosphorylated by phosphorylase kinase to yield synthase b2. 2. Dephosphorylation and activation of synthase b2 by the catalytic subunits of protein phosphatase-1 (PP-1c) and protein phosphatase-2A (PP-2Ac) was studied. The apparent Km of PP-1c and PP-2Ac were 3.3 microM and 6.2 microM, respectively. The apparent Vmax of PP-1c was about two times larger than that of PP-2Ac. 3. Ligands with phosphate moiety (AMP, glucose-6-P at high concentration) caused an inhibition in dephosphorylation by both phosphatases. Spermine inhibited the dephosphorylation by PP-1c and stimulated the action of PP-2Ac. Therefore it can be employed to distinguish the phosphatases using synthase b2 as substrate.

Animals↗
PubMed1989

Antiviral activity of tiazofurine against barley stripe mosaic virus.

Tiazofurine (2-beta-D-ribofuranosylthiazole-4-carboxamide) was found to inhibit replication of barley stripe mosaic virus (BSMV) in barley and wheat plants. Treatment with this nucleoside analogue delayed and inhibited symptom development and suppressed virus multiplication. The most effective concentration applied twice as a foliar spray 3 h and one day after inoculation, was 10(-3) M. Decreased virus multiplication was obtained without marked phytotoxicity. Three weeks after treatment the antiviral effect declined.

Antiviral Agents↗
PubMed1989

The role of duodenal erosions in the occurrence of upper gastrointestinal haemorrhage.

It is well known that gastric erosions and the so called erosive gastritis, cause about 20-30% of massive upper gastrointestinal haemorrhage. Our endoscopic material was examined in order to answer the following questions: at what ratio duodenal erosions induced massive bleeding, what their emergence can be attributed to, what connection may be found between duodenal ulcers and duodenal erosions and what is the rate of recovery of such patients. We found that: 1) duodenal erosions may occur together with gastric erosions, therefore they can jointly induce massive bleeding; 2) duodenal erosions may be associated with duodenal ulcer but haemorrhage originates from the erosion and the ulcer itself does not bleed; 3) duodenal erosion in itself might induce bleeding, 4) the intensity of bleeding, if there is no haemorrhage from other places, is not so severe, as the one originating from gastric erosions, and with the application of conservative treatment it usually stops within a short period of time; 5) the inducing factor is generally massive alcohol consumption; drug intake is rare as a cause for duodenal erosions. The early and exact diagnosis of duodenal erosions is all the more important in that it might safeguard the patient from unnecessary operations.

Duodenal Diseases↗
PubMed1989

[Epidemiological surveys of formaldehyde and nitrogen dioxide levels in indoor air].

The influence of HCHO and NO2 on clinical, haematological, immunological, sensory and lung function parameters were tested in 129 children out of 3 classes. As part of a biological monitoring programme formic acid content in urine was determined. Concentration of the pollutants in indoor air was measured by means of passive samples.

Air Pollutants↗
PubMed1989

[Microprobe study of bones in the determination of individual age].

Potassium and phosphorus levels and the Ca: P ratio were determined in autopsy material taken from the compact bone substance of the right femur of 25 individuals of various age and either sex. Studies were made under a Tesla BS-300 scanning electron microscope connected to an EDAX-149-10 X-ray detector and a BMG-38100 X-ray analyser using 15 kV accelerating voltage, 100 pA test-current and 20 s measuring time. Different bone substances (lamellae, Haversian canals, interstitial bone) showed similatr Ca: P ratios (p greater than 0.05). However, mean mol-ratio was found to decrease with age and this was still significant (p greater than 0.05) at 95% level. The equation of the regression line was: y = -0.0013x + 1.8275, where y represents Ca: P ratio x the age. There was a close correlation between the molar ratio of Ca and P which enables this method to be applied for the assessment of individual age in forensic medicine and paleoanthropology.

Age Determination by Skeleton↗
PubMed1988

Pesticide use related to cancer incidence as studied in a rural district of Hungary.

General mortality analysis showed an increasing tendency of circulatory diseases in two villages examined. Respiratory diseases and suicide were more frequent in the village with greater pesticide use (village I). The relative risk (RR) of gastric cancer for men is significantly higher in village I (high rate of pesticide use) than in the county as a whole (RR, 1.65; 95% confidence interval (CI), 0.96-2.83) and also in relation to the national data (RR, 3.20; 95% CI, 1.91-5.36). Since the nitrate concentration in the drinking water, the drug consumption, smoking and eating habits are similar in the two villages, and since alcohol consumption is higher in village II (moderate rate of pesticide use), it seems that nitrosable pesticides may play a role in the etiology of stomach cancer. This is supported by the fact that a higher number of gastric cancer cases was found where larger quantities of nitrosable pesticides had been used.

Adult↗
PubMed1988

An indirect method for quantitation of cellular zinc content of Timm-stained cerebellar samples by energy dispersive X-ray microanalysis.

The absolute concentration of zinc in the Purkinje cells of the rat cerebellum was determined by means of energy dispersive X-ray microanalysis (EDAX). Gelatine blocks with known zinc concentrations were stained by Timm's sulphide-silver method, and their silver concentrations were measured by EDAX. A linear correlation was found between the zinc and silver concentrations and this linear function was used as a quantitative calibration for evaluation of sulphide-silver staining, after perfusion with sodium-sulphide solution, fixation with glutaraldehyde, cryostat sectioning and staining of cerebellar samples in Timm's reagent.

Animals↗
PubMed1988

Regulation of the dephosphorylation of phosphorylase A by glucose, AMP and polyamines.

1. The effect of glucose, caffeine, AMP and polyamines was investigated on the dephosphorylation of phosphorylase a by the catalytic subunits of protein phosphatase-1 and -2A. 2. Caffeine at 1-20 microM inhibited the dephosphorylation of the dimeric phosphorylase a at 37 degrees C using skeletal muscle enzymes; 0.1-10 mM of caffeine enhanced the rate of dephosphorylation greatly at 13 degrees C and slightly at 37 degrees C. 3. alpha-D-Glucose was more effective in accelerating both the dephosphorylation and the tryptic digestion of phosphorylase a than the beta-anomer. 4. Polyamines were found to moderate the inhibitory effect of AMP at concentrations which may occur in the tissues. In the presence of 5 mM glucose polyamines could cancel the AMP inhibition of the dephosphorylation of liver phosphorylase a by hepatic protein phosphatase-1 and -2A.

Adenosine Monophosphate↗