Biomedical subjects

I Tóth

Publications and source records attributed to I Tóth.

At least 37 records · Page 2Linked to original sources

PubMed2000

Characterization of intestinal cnf1+ Escherichia coli from weaned pigs.

Escherichia coli isolated from 204 cases of porcine postweaning diarrhoea were tested by PCR for the genes of cytotoxic necrotic factors (CNF) and of cytolethal dystending toxin (CDT). Selected strains were also examined by PCR for the presence of papC-, sfa-, f17-, f18-, and afa-specific sequences encoding P, S, F17, F18 fimbriae and afimbrial adhesins. A 5.9% (12/204) of the strains had cnf1 gene, and two of them had cdt gene as well. Further six cdt+ strains were detected which were cnf-negative. Most of the cnf1+ strains belonged to serogroups O2, O6, O8, O54 characteristic of necrotoxic E. coli (NTEC) of humans. All the cnf1+ strains possessed the genes for P or S fimbriae or both, but were negative for F4, F17, or F18 or afimbrial adhesins. Results suggest that these enteric isolates may have entero- and/or uropathogenic significance in weaned pigs, and may have zoonotic potential for humans.

Animals↗

PubMed2000

[Role of surgery, its results and complications, in the combined treatment of primary gastric non-Hodgkin lymphoma].

During ten years 580 patients have been treated for gastric tumour in our department, 510 of them were operated on. Resection could be performed in 296 cases. 17 resections, 5.7 per cent of all were performed because of primary non-Hodgkin gastric lymphoma. No gastric lymphoma was found among the non-resected patients. The preoperative histological diagnosis was correct only in 8 cases. MALT origin could be proved in 5 patients. Synchronous adenocarcinoma and lymphoma was diagnosed in 2 patients. Staging was decided according to Lugano classification. There were six stage I, four stage II, and seven stage IV patients. 8 subtotal and 9 total gastrectomy was performed, 5 were extended and 2 were combined. R0 resection could be carried out in five stage I, two stage II and in one stage IV patient. We lost 2 patients in the postoperative period. Patients were treated with adjuvant chemotherapy (VEP, CHOP) except for 2 patients with low grade MALT lymphoma. The likelihood of one-year survival is 73 per cent, average two-year survival is 63 per cent. When the tumour is operable by total gastrectomy we suggest to perform splenectomy as well, despite of the fact that some postoperative complications can be related to it. We think it is reasonable to perform palliative resection in cases of locally extended stage IV tumours, which affect the patient's quality of life: to cease the pain, passage troubles, bleeding and to improve the conditions for adjuvant treatment.

Aged↗

PubMed1999

Novel lipoamino acid- and liposaccharide-based system for peptide delivery: application for oral administration of tumor-selective somatostatin analogues.

Lipoamino acid and liposaccharide conjugates of somatostatin analogue TT-232 were synthesized to modify the physicochemical properties of the parent peptide. The relative position, the number, and the nature of the lipid and/or saccharide moieties were varied. Experiments in vitro clearly showed that many compounds modified at the N- and/or C-terminus with lipid or sugar moieties retained the biological activity of the parent compound. An interesting construct was synthesized containing lipid and sugar units at opposite ends of the somatostatin analogue, so that the entire molecule could be considered as an amphipathic surfactant.

Administration, Oral↗

PubMed1998

[Effect of somatostatin-octreotide on secretion of adrenocorticotropin, cortisol and neuro-hypophyseal hormones in acromegaly].

The present work was aimed at studying the combined effects of somatostatin and corticotropin releasing hormone on the activities of the pituitary-adrenocortical axis and neurohypophysis. Patients with active acromegaly were intravenously injected with a 100 micrograms human corticotropin releasing hormone bolus before and after a 3-month subcutaneous treatment with somatostatin-octreotide (SMS 201 995; Sandostatin; 200 micrograms t. i. d.). When the Sandostatin effect was investigated, corticotropin releasing hormone test was started 2 hrs after its first daily dose. Peripheral venous blood samples were taken before and 20, 60, 90 and 120 min after the corticotropin releasing hormone load. Plasma corticotropin, arginine-8-vasopressin and oxytocin were measured by radioimmunoassay, and serum cortisol by fluorimetry. In healthy subjects, corticotropin releasing hormone stimulus elicited increases of plasma corticotropin, serum cortisol, plasma arginine-8-vasopressin and oxytocin levels by 186, 41, 178 and 58 per cent, respectively. Untreated acromegalics exhibited missing arginine-8-vasopressin, blunted corticotropin, and normal oxytocin and cortisol responses. Sandostatin therapy improved the arginine-8-vasopressin reaction, suppressed the basal levels of corticotropin and cortisol with the maintenance of cortisol stimulability; the peak-reaction of corticotropin became normal in two patients, however, with a shortened duration of response. Diuresis of the patients increased under the treatment. Sandostatin markedly alleviated the clinical symptoms and suppressed the growth hormone secretion, but did not influence the size of the pituitary adenomas. Among other factors, the alterations of growth hormone and cortisol may be hypothesized to take part in the changes of the corticotroph and neurohypophysial functions.

Acromegaly↗

PubMed1998

Partial inhibition of amplifications by primers of EHEC genes.

Diagnostic value of multiplex polymerase chain reaction (PCR) was examined by using three primer pairs, specific for the common conserved region of stx1 and stx2, eae and an enterohaemolysin A gene (ehxA). The sensitivity in respect of each amplicon decreased with three exponents comparing to the individual PCR reactions. These PCR reactions were partially inhibited by the presence of certain additional primers. This inhibitory effect was template-concentration dependent, and was partially balanced by usage of increased amount of dNTP. Taq DNA polymerase in a range of 0.3-1.25 U/reaction did not influence the inhibition. The same inhibition was detected if the annealing temperature was changed from 48 degrees C to 57 degrees C. Pairs of EHEC primers inhibited a Salmonella enteritidis virulence-plasmid specific gene amplification, as well. Theoretical inhibiting effects were predicted by Primer Premier software but our observations can be sufficiently explained neither by the competitions between the specific and aspecific amplifications nor by the inhibition caused by dimerization of primers.

Animals↗

PubMed1998

Characterisation of an echovirus type 11' (prime) epidemic strain causing haemorrhagic syndrome in newborn babies in Hungary.

Echovirus 11' (prime) isolates from an epidemic of haemorrhagic syndrome in departments of obstetrics in Hungary have been characterised. The leading component of the clinical disease was carditis and its lethal outcome occurred in 13 newborn babies. Maternal immunity was found to be absent even in women of 41 years of age. The application of monovalent oral poliovirus type 1 vaccine prevented the progress of the epidemic within two weeks. Nevertheless, a serological survey among primovacinees of 3-15 months of age revealed that 20% of the babies seroconverted without clinical symptoms during the epidemic. Serological evidence showed that the echovirus 11' infection was unable to interfere with the efficacy of oral poliovirus vaccine (OPV), since seroconversion rates of primovaccinees did not differ significantly from those in the group seroconverted also to echovirus 11' during the vaccination campaign. A 440 nucleotide (nt) fragment of the 5'-non-translated region of 12 epidemic echovirus 11' isolates and 26 echovirus prototype strains was amplified by a nested reverse transcription-polymerase chain reaction (RT-PCR) and analysed using three different restriction endonucleases. The 5'-regions of the echovirus 11' isolates were found to be identical to each other but different from that of the prototype echovirus 11 (Gregory) strain. The results indicate that echovirus 11' isolates underwent genetic changes in the 5'-end and P1 region of the genome before the onset of the epidemic.

5' Untranslated Regions↗

PubMed1997

Progesterone in Periplaneta americana and Neobellieria bullata adults from the procuticle phase until first progeny production.

A significant amount of progesterone-like immunoreactive material (150 ng/g) was measured by EIA in the procuticle phase of adult of both sexes of Periplaneta americana. This peak markedly decreased to 1-10 ng/g during sclerotization and was unlikely to be of dietary origin. In the case of 0-hr-old P. americana adults 96-98% of progesterone-like material was localized in the digestive tract and Malpighian tubules. In contrast, a relatively low level of progesterone-like immunoreactive material was measured in 0-hr-old Neobellieria bullata adults. Activity of 3beta-HSD/isomerase converting pregnenolone to progesterone was high (22-43 fmol/mg protein/20 min) in 0-hr-old P. americana adults and significantly fell during sclerotization. High progesterone levels (13-16 ng/g), measured by HPLC-RIA, coexist with high levels of 3beta-HSD/isomerase activity. Orally active human contraceptives (ethisterone, ethynodiol, ethynodiol diacetate, lynestrenol, mestranol, norgestrel, norethynodrel, tamoxifen citrate, and mifepristone) which act on mammalian steroid receptors had no significant effects on progeny production in either polytrophic or meroistic insect ovaries even at concentration of 5000 mg/kg.

3-Hydroxysteroid Dehydrogenases↗

PubMed1997

Activity and inhibition of 3-beta-hydroxysteroid dehydrogenase/delta-5-4-isomerase in human skin.

Activity and inhibition of 3 beta-hydroxysteroid dehydrogenase/delta 5-4-isomerase, a key example of biosynthesis of androgenic steroids, in human skin were studied. Whole-width dermal tissue specimens excised from various regions of the male and female body were investigated with an in vitro radioenzyme assay method using dehydroepiandrosterone as substrate. The Michaelis-Menten constant of the enzyme was found to be Km = 10nM and the maximal velocity was Vmax = 0.625 pmol produced 4-androstene-3,17-dione/mg protein/20 min. Activity of 3 beta-hydroxysteroid dehydrogenase/delta 5-4-isomerase in male inguinal skin (n = 8) was 0.132-0.412, in female abdominal skin (n = 4) 0.140-0.255, in perineal skin (n = 4) 0.138-0.962 pmol/mg protein/20 min. The synthetic steroids cyproterone acetate, 4-MA and epostane proved to be potent inhibitors, IC50 values were 150, 6.2 and 1.45 nM, respectively.

Adult↗

PubMed1996

In vitro inhibition of testicular delta 5-3 beta-hydroxysteroid dehydrogenase and prostatic 5 alpha-reductase activities in rats and humans by strogen forte extract.

Clinical findings indicate that Strogen forte (a standardized extract of the plant Sabalis serrulata) can be use successfully in the medical treatment of benign prostatic hyperplasia. The aim of the present study was to investigate the possible inhibitory effects of the Strogen forte extract on rat and human testicular delta 5-3 beta-hydroxysteroid dehydrogenase (delta 5-3 beta-HSD) and prostatic 5 alpha-reductase (5 alpha-R). Strogen forte proved to be a direct inhibitor of medium effectivity, with similar IC50 values for rat testicular delta 5-3 beta-HSD (400 +/- 23 micrograms/ml) and human testicular delta 5-3 beta-HSD (212 +/- 8.6 micrograms/ml). 5 alpha-R activities were analysed by in vitro incubation of rat and human prostatic tissue homogenates with 14C-labelled testosterone as substrate in KRPG-DTT medium (pH = 7.4) with NADPH coenzyme, in air, at 37 degrees C, in the presence of Strogen forte extract. The results clearly demonstrate that Strogen forte is a potent inhibitor of prostatic 5 alpha-R, with IC50 values of 385 +/- 35.6 micrograms/ml for rat and 245 +/- 64.6 micrograms/ml for human prostatic 5 alpha-R. The present study has revealed that this plant extract inhibits not only prostatic 5 alpha-R, but also testicular delta 5-3 beta-HSD.

3-Hydroxysteroid Dehydrogenases↗

PubMed1995

In vitro binding of 16-methylated C18 and C19 steroid derivatives to the androgen receptor.

The binding of androgens and structurally related analogues to the androgen receptor was studied. The in vitro experiments were carried out with cytosol of castrated rat prostate, using [3H]R1881 (methyltrienolone) as radioligand. The binding parameters measured were Kd = 1.25 x 10(-10) M and Bmax = 111 fmol (mg protein)-1. Ligand specificity was confirmed by competition experiments with known androgen, oestrogen and progestogen ligands. The receptor binding of substituted steroids was studied. The RBAs (relative binding affinities) of our recently synthetized 16-alkyl steroids were low. The only exception was the 17 beta-hydroxy-16 beta-methylestr-4-en-3-one, which exhibited the remarkable RBA of 22.9%.

Animals↗

PubMed1994

[Analysis of steroids and binding proteins in the blood of women with androgenetic alopecia].

Specific and sensitive radioimmune methods were used to study the steroid levels and binding capacities of their binding proteins in the serum of 30 women with androgenetic alopecia, in order to establish the proportions of the patients in whom hyperandrogenism or hypercorticism can be detected. It was found that the serum testosterone, dehydroepiandrosterone sulphate and cortisol levels did not differ from those for healthy women except dehydroepiandrosterone which was high. In 5 cases (16.6%), the binding capacity of the "sex hormone-binding globulin" was pathologically low, while in 6 patients (20%) the "free androgen index" was elevated. The binding capacity of the "corticosteroide-binding globulin" was pathologically low in 4 of 21 cases (19%) while the "free cortisol index" was high in 5 of these 21 patients (23.8%). Diane treatment (2 mg cyproterone acetate and 50 micrograms ethinyl-oestradiol)--was administered during 2-5 cycles (8 cases), the pathological dehydroepiandrosterone and dehydroepiandrosterone sulphate levels normalized, the testosterone level decreased to the lower limit of the normal range, the binding capacity of the "sex hormone-binding globulin" increased considerably, and the "free androgen index" fell below the normal range. Diane treatment, an essential improvement was observed in the condition of the patients: the hair became less greasy and its tendency to fall out was likewise moderated.

Alopecia↗

PubMed1994

In vitro inhibitory effects of 16-methyl-substituted steroids on 5 alpha-reductase in rat and human prostates.

The inhibitory effects (IC50) of 16-methyl steroids on 5 alpha-reductase were studied. The in vitro experiments were carried out with homogenates of rat and human prostates. The investigated 16-methyl steroids were found to be weak inhibitors. In comparison with the known 5 alpha-reductase inhibitor 4-MA (17 beta-N, N-diethylcarbamoyl-4-methyl-4-aza-5 alpha-androstan-3-one), the relative IC50 values of the studied compounds are 4.7 times or more greater than 4-MA in human prostate and 23.5 times or more greater than 4-MA in rat prostate. The IC50 values increase in the sequence 16 alpha-, 16 beta- and 16,16-dimethyl derivatives. In human prostate homogenates IC50 varies between 0.6 and 120, while in rat it ranges from 1.6 to 1000 microM. This shows that the enzyme of the human prostate is more sensitive than that of the rat prostate to the methyl-substituted compounds.

Animals↗

PubMed1994

The intersubunit region of the influenza virus haemagglutinin is recognized by antibodies during infection.

The influenza virus haemagglutinin has an important role in the infectious cycle of the virus and carries multiple B and T cell epitopes. It is synthesized as a single polypeptide chain but viral infectivity depends on its post-translational enzymatic cleavage. The cleavage site of a trypsin-like enzyme responsible for this modification is found in the most conserved intersubunit region of the molecule. In this study the role of this region in antibody recognition was investigated. Synthetic peptides comprising the intact and cleaved forms of the intersubunit segment were used to examine the specificity of virus- or peptide-induced antibodies. The immune response elicited by viral infection resulted in the appearance of antibodies capable of neutralizing the virus without interfering with its binding to the receptor. A monoclonal antibody (MoAb) of such functional properties was shown to recognize the intact intersubunit region both in the uncleaved haemagglutinin molecule and in a 25-mer synthetic peptide comprising the intact intersubunit region. Specificity and functional studies revealed the conformation-dependent recognition of the C-terminal segment of the haemagglutinin 1 subunit by this MoAb. The binding of the antibody was shown to inhibit the trypsin-mediated cleavage of the haemagglutinin molecule and the membrane fusion event. The enzymatic cleavage of the haemagglutinin was demonstrated to abolish antibody recognition of the infective virus suggesting an escape mechanism mediated by the functional destruction of this highly conserved region. The synthetic peptide corresponding to the intact intersubunit region is characterized by an ordered structure and is able to elicit an antibody response in BALB/c mice while its subfragments are nonimmunogenic. Furthermore, this peptide elicited a protective immune response demonstrated by in vivo experiments.

Amino Acid Sequence↗

PubMed1994

Examination of verocytotoxin producing capacity and determination of the presence of Shiga-like toxin genes in human Escherichia coli isolates.

A total of 93 wild type Escherichia coli of human origin (mostly representing intestinal isolates from Hungary) were examined for the presence of Shiga-like-toxin (SLT) genes using SLT-I, SLT-II and enterohemorrhagic E. coli (EHEC) specific DNA probes. The structural genes of the above specificity were labelled by random priming using 32-P-dCTP. E. coli strains investigated represented 16 serogroups: O1, O2, O4, O5, O6, O18, O25, O26, O45, O55, O111, O125, O126, O128, O157, O165, members of which were likely to produce verotoxin (VT) and strains of serotypes O11:NM, ONT:NM isolated from six haemorrhagic uraemic syndrome (HUS) patients. Out of these strains 51 were examined for in vitro VT production capacity. Only one strain (an O26:H11 from Germany) produced VT. This was also the only strain which proved to be positive with one of the SLT probes (SLT-II), and with the EHEC probe. From this strain a phage was isolated which was proven to be nonconvertible. These data support epidemiological and clinical observations about the very low occurrence or absence of EHEC in Hungary, in contrast to many European countries.

Animals↗

PubMed1994

[In vitro inhibitory effects of 16-methyl-substituted steroids on 5 alpha-reductase in rat and human prostates].

The inhibitory effects (IC50) of 16-methyl steroids on 5 alpha-reductase were studied. The in vitro experiments were carried out with homogenates of rat and human prostates. The investigated 16-methyl steroids were found to be weak inhibitors. In comparison with the known 5 alpha-reductase inhibitor 4-MA, the relative IC50 values of the studied compounds are 4.7 times or more greater than 4-MA in human prostate and 23.5 times or more greater than 4-MA in rat prostate. The IC50 values increase in the sequence 16 alpha, 16-beta- and 16,16-dimethyl derivatives. In human prostate homogenates IC50 varies between 0.6 and 120, while in rat it ranges from 1.6 to 1000 microM. This shows that the enzyme of the human prostate is more sensitive than that of the rat prostate to the methyl-substituted compounds. Acylation of the 17-hydroxy group significantly increases the IC50 values (cf. 8,11: from 4.8 to 23.5 and from 0.52 to 0.62;9,12: from 26.0 to 170.0 and from 0.58 to 1.4;15,17: from 3.9 to 35.0; and 16,18: from 5.6 to 58.0 microM). Whereas lack of a 19-CH3 group improves the inhibitory effect in the 16-unsubstituted compounds (1,19;14,22), the reverse hold in the 16-methylated derivatives (9,20; 10,21; 15,23; 16,24).

5-alpha Reductase Inhibitors↗

PubMed1992

In vitro study of rat prostate 5 alpha-reductase activity and its inhibition.

A simple and rapid method of measuring 5 alpha-reductase (5 alpha-R) activity and of determining the kinetic parameters (KM and Vmax) of the enzyme is described. The 5 alpha-R activity in the homogenate of the prostate of Wistar rats aged 8-12 weeks was established, and the effects of natural and synthetic steroids and of non-steroidal antiandrogens (IC50) upon the 5 alpha-R activity were studied. Of the natural steroids, 17-OH-progesterone was found to have the highest inhibitory effect (IC50 = 1.35 microM), followed in decreasing order by progesterone (IC50 = 5.0 microM) and 4-androstene-3,17-dione (IC50 = 21.6 microM). Oestradiol-17 beta had practically no inhibitory effect. Of the synthetic steroids, 4-MA had the highest inhibitory effect (IC50 = 0.068 microM), followed by nortestosterone (IC50 = 7.4 microM) and RU-486 (Mifepristone) (IC50 = 115 microM). Even at 1000 microM, cyproterone acetate exerted no inhibitory effect. Of the nonsteroidal compounds, ketoconazole proved a weak inhibitor (IC50 = 115 microM), while flutamide was practically ineffective.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗

PubMed1992

Low-dose aminoglutethimide therapy without glucocorticoid administration. Clinical and hormonal findings.

Eleven postmenopausal patients with advanced breast cancer were assessed for their response and endocrine changes to low-dose aminoglutethimide (250 mg twice a day) therapy without steroid administration. In 7 cases an objective response was registered; 1 patient had a stabilization of the disease lasting for 9 months. Significant falls in plasma estrogen and rises in plasma androgen levels were observed, while those of cortisol and ACTH remained essentially unchanged. No serious side effects occurred.

Aged↗

PubMed1992

Bacteriocin-like antagonism in Yersinia enterocolitica.

A total of 121 Yersinia enterocolitica O3 isolates from patients with gastroenteritis and 37 Y. enterocolitica reference strains with different O antigens were tested for bacteriocine production and sensitivity. By using cross-streaking method strains belonging to serogroups of O5; O7,8; O7,13; O11; O11,23; O13,27; O17; O19,8 and O34 produced bacteriocin-like substances. None of the Y. enterocolitica O3 strains produced bacteriocin-like material and most of them were uniformly sensitive against the bacteriocin-like material produced by strains of serogroups O7,8; O7,13; O13,27 and O19,8. By sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) significant differences were demonstrated in the whole cell protein patterns of Y. enterocolitica reference strains belonging to different serogroups in the range of 33-47 kilodalton (kDa). Out of the ten examined bacteriocin-like material producer strains only one strain harboured a plasmid of about 60 megadalton (MDa).

Antibiosis↗