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Biomedical subjects

M Takács

Publications and source records attributed to M Takács.

At least 19 recordsLinked to original sources
PubMed2007

Variability of the PreS1/PreS2/S regions of hepatitis B virus in Hungary.

Infection with the hepatitis B virus can occur perinatally, parenterally, or sexually, and it can cause acute or chronic liver diseases. Phylogenetic analysis of the virus has led to its classification into eight genotypes (A-H), which show a characteristic worldwide distribution. The aim of this study was to reveal the HBV genotypes present in Hungary and to investigate a nosocomial and an intrafamilial outbreak. The collected samples were tested by nested PCR, and a 650-nucleotide-long segment of the preS1/preS2/S region was sequenced. As no previous genotype data were available from Hungary, sera of 24 HBsAg-positive patients were collected from different regions of the country. They also served as control samples for the molecular epidemiologic study. Nineteen of them carried genotype D of hepatitis B virus, and five of them carried genotype A. Twenty-nine patients from a haemato-oncology unit were affected in a nosocomial outbreak. The patients had haematological and/or oncological diseases, most of them were immunosuppressed. In twenty-eight cases, based on phylogenetic analysis of the viruses, there was presumably a common source of infection, and an epidemiological investigation showed that the infections seemed to be hospital-acquired. In the intrafamilial outbreak, two asymptomatic carrier children infected their foster mother. The three sequences were totally identical.

Amino Acid Sequence↗
PubMed2005

Genotypic distribution of human herpesvirus-8 strains circulating in HIV-positive patients with and without Kaposi's sarcoma in Hungary.

Open reading frame (ORF) 26 of human herpesvirus-8 (HHV-8) from peripheral blood samples of 15 Hungarian HIV-positive patients with or without Kaposi's sarcoma (KS) were amplified and sequenced. Four variants of HHV-8 were identified according to ORF 26 genotyping. Most of the samples were shown to be subtype A3, however, subtypes A, B3/C2/C2', and C3 (ORF 26 region) were also identified. The ORF 26 subtypes A and C3 of HHV-8 were only recovered from patients with KS while A3 was dominant in KS negative cases. The amplification of the hypervariable ORF K1 gene was successful only from 2 of the same 15 patients. Sequence analysis of the amplified ORF K1/VR1 regions identified subtype A3 from 2 patients with AIDS-associated KS. A novel ORF K1/VR1 variant belonging to subgroup A' was detected in a different sample in one of them. Amplification of the ORF K15, another representative locus for HHV-8 genotyping, was not successful from any of the peripheral blood samples. Unsuccessful amplification of the terminal K1 and K15 ORFs from peripheral blood samples suggests that KS biopsy specimens are needed for complete genotyping of HHV-8 strains from Hungary.

Acquired Immunodeficiency Syndrome↗
PubMed2001

Molecular characterization and heterologous expression of hypCD, the first two [NiFe] hydrogenase accessory genes of Thermococcus litoralis.

The hypCD genes, encoding the counterparts of mesophilic proteins involved in the maturation of [NiFe] hydrogenases, were isolated from the hyperthermophilic archaeon Thermococcus litoralis. The deduced gene products showed 30-40% identity to the corresponding mesophilic proteins. HypC and HypD were synthesized by the T7 expression system. Heterologous complementation experiments were done in Escherichia coli and Ralstonia eutropha strains lacking functionally active hypC and hypD genes. Only the cytoplasmic hydrogenase of R. eutropha could be processed by HypD from T. litoralis. This was the first demonstration of mesophilic hydrogenase processing using a hyperthermophilic archaeal accessory protein to produce an active enzyme.

Archaeal Proteins↗
PubMed2001

Relative deficiency in CpG dinucleotides is a widespread but not unique feature of Gammaherpesvirinae genomes.

Since methylcytosine is relatively unstable, a deficiency of CpG dinucleotides and accumulation of mutations that manifest as TpG (and its complement CpA) is a diagnostic feature of higher eukaryotic DNA sequences subjected to methylation by DNA (cytosine-5) methyltransferases. Latent viral genomes may also be affected by DNA methylation in their host cells. We calculated, therefore, frequencies of dinucleotides in 20 completely sequenced herpesvirus genomes. We found a relative deficiency of CpG dinucleotides and a surplus of TpG + CpA dinucleotides in all lymphotropic gammaherpesvirus genomes except for two strains of rhesus rhadinovirus. DNAs of two strains of human herpesvirus 7, a betaherpesvirus targeting helper T cells, and equine herpesvirus 4, an alphaherpesvirus residing in the lymphoreticular system, also had a moderate CpG deficiency and TpG + CpA surplus. In contrast, most members of Alpha-, and Betaherpesvirinae subfamilies contained a relative surplus of CpG dinucleotides in their DNAs. Our data are consistent with the idea that methylated latent genomes are involved, after reactivation and productive replication, in the natural transmission cycle of most members of Gammaherpesvirinae and certain lymphotropic members of Alpha- and Betaherpesvirinae.

Alphaherpesvirinae↗
PubMed2000

Genetic subtypes of HIV type 1 in Hungary.

We examined the diversity of HIV-1 subtypes in 11 adults from Hungary, using the heteroduplex mobility assay (HMA) and DNA sequencing. HMA results showed that HIV-1 gp120 sequences from 10 patients were of subtype B, whereas 1 patient, infected in Africa, carried a subtype C strain. DNA sequencing confirmed the HMA results and revealed a high intrasubtype diversity in the C2V3 region of env in different clade B isolates, which suggests multiple introduction of subtype B to Hungary. This study shows that subtype B is the predominant HIV-1 clade in Hungary.

Acquired Immunodeficiency Syndrome↗
PubMed2000

Photochemical and chemical oxidation of mexiletine and tocainide. Structure elucidation of the major products.

Mexiletine (mex) and tocainide (toc) are antiarrhythmic drugs of closely related structure. Several degradation products are formed by interaction with both light and oxidizing agents in the case of mex, and only by oxidants with toc. On the basis of the identified structures, the decomposition reactions can be classified into two types (Scheme 1). Type I is an oxidative cyclization reaction producing the oxazepine derivative 1 from mex and the diazepine derivative 3 from toc. In reaction type II side chain oxidized products (2 or 4 and 5) are formed. While tocainide.HCl has proved to be photostable, in solid mexiletine HCl the oxazepine derivative was observed after several days' exposure to direct sunlight. The pharmacopoeias (Ph.Eur.3, USP 23), however, do not prescribe light-protection for mex.HCl.

Anti-Arrhythmia Agents↗
PubMed2000

Nucleotide sequences and mutations of the 5'-nontranslated region (5'NTR) of natural isolates of an epidemic echovirus 11' (prime).

An echovirus 11' (prime) virus caused an epidemic in Hungary in 1989. The leading clinical form of the diseases was myocarditis. Hemorrhagic hepatitis syndroms were also caused, however, with lethal outcome in 13 newborn babies. Altogether 386 children suffered from registered clinical disease. No accumulation of serous meningitis cases and intrauterine death were observed during the epidemic, and the monovalent oral poliovirus vaccination campaign has prevented the further circulation of the virus. The 5'-nontranslated region (5'-NTR) of 12 natural isolates were sequenced (nucleotides: 260-577). The 5'-NTR was found to be different from that of the prototype Gregory strain (X80059) of EV11 (less than 90% identity), but related to the swine vesicular disease virus (D16364) SVDV and EV9 (X92886) as indicated by the best fitting dendogram. The examination of the variable nucleotides in the internal ribosomal entry site (IRES) revealed, that the nucleotide sequence of a region of the epidemic 5'-NTR was identical to that of coxsackievirus B2. Five of the epidemic isolates were found to carry mutations. Seven EV11' IRES elements possessed identical sequences indicating, that the virus has evolved before its arrival to Hungary. The comparative examination of the suboptimal secondary structures revealed, that no one of the mutations affected the secondary structure of stem-loop structures IV and V in the IRES elements. Although it has been shown previously, that the echovirus group is genetically coherent and related to coxsackie B viruses the sequence differences in the epidemic isolates resulted in profound modification of the central stem (residues 477-529) of stem-loop structure No.V known to be affecting neurovirulence of polioviruses. Two alternate cloverleaf (stem-loop) structures were also recognised (nucleotides 376 to 460 and 540 to 565) which seem to mask both regions of the IRES element complementary to the 3'-end of the 18 S rRNA (460 to 466 and 561 to 570), thus probably diminishing initiation of translation. The possible biological importance of the alternative cloverleaf structures is supported by the fact that neither the 17 variable nucleotides nor the two mutations of epidemic isolates within the regions seem to modify the predicted alternative secondary structures in EV11, SVDV and CBV1-4.

5' Untranslated Regions↗
PubMed2000

Analysis of the genetic variability of the 1st (CCC/ACC, P52T) and the 10th exons (bp 1012-1704) of the TSH receptor gene in Graves' disease.

We determined the genetic variability of the 1st (CCC/ACC, P52T polymorphic variant) and 10th exons (bp 1012-1704) of the TSH receptor (TSHR) gene in Graves' disease. A total of 101 Graves' patients and 163 control subjects were screened. The A253 mutant allele was carried by nine patients with Graves' disease (8.91%) and 13 control subjects (7.98%) in heterozygous genotype. No significant difference in the frequency of the mutant allele was found between Graves' patients and control subjects. These results provide evidence that the A253 polymorphism has no genetic relevance in Graves' disease. Moreover, the DNA nucleotide sequence of 693 bp of the 10th exon (bp 1012-1704) of the TSHR gene was determined in 15 Graves' patients. Six patients were homozygous for the wild-type allele and nine were heterozygous for the mutant allele at the 253rd nucleotide of the first exon. No polymorphism was found in the DNA sequences obtained from leukocytes of Graves' patients, similarly to the sequences obtained from the nine control subjects. None of the nine patients carrying the A253 polymorphism in the 1st exon of the TSHR had polymorphism in the examined part of the 10th exon, including two additional patients whose thyroid tissue was directly analysed. In all likelihood, the polymorphisms of the examined regions of either the 1st or the 10th exon of the THSR gene do not contribute to the genetic susceptibility to Graves' disease.

Adolescent↗
PubMed2000

Recent advances in biohydrogen research.

A fundamental and principal difficulty of the future energy supply is that the formation of fossil fuels is much slower than the rate of their exploitation. Therefore the reserves which can be recovered in an energetically feasible manner are shrinking parallel with an increasing world-wide energy demand. Among the alternative energy carriers, hydrogen is preferred because it is easy to transport and store and it burns to environmentally friendly water vapour when utilized. Hydrogen can be produced in biological systems, however, our understanding of the molecular details is just emerging.

Biotechnology↗
PubMed1999

Genes involved in hydrogen and sulfur metabolism in phototrophic sulfur bacteria.

The dsr genes and the hydSL operon are present as separate entities in phototrophic sulfur oxidizers of the genera Allochromatium, Marichromatium, Thiocapsa and Thiocystis and are organized similarly as in Allochromatium vinosum and Thiocapsa roseopersicina, respectively. The dsrA gene, encoding the alpha subunit of 'reverse' siroheme sulfite reductase, is also present in two species of green sulfur bacteria pointing to an important and universal role of this enzyme and probably other proteins encoded in the dsr locus in the oxidation of stored sulfur by phototrophic bacteria. The hupSL genes are uniformly present in the members of the Chromatiaceae family tested. The two genes between hydS and hydL encode a membrane-bound b-type cytochrome and a soluble iron-sulfur protein, respectively, resembling subunits of heterodisulfide reductase from methanogenic archaea. These genes are similar but not identical to dsrM and dsrK, indicating that the derived proteins have distinct functions, the former in hydrogen metabolism and the latter in oxidative sulfur metabolism.

Bacteria↗
PubMed1999

Why do patients seek treatment in hospitals of complementary medicine?

OBJECTIVE: This exploratory study evaluated patients' reasons for entering a complementary (alternative) medicine hospital by ranking 15 medical and psychosocial factors that were thought to influence this choice. SUBJECTS AND OUTCOME MEASURES: Two hundred patients (200) from two complementary hospitals, one focusing on Traditional Chinese Medicine and one on the Western type of complementary medicine, completed an extensive questionnaire at the beginning of their inpatient treatment. The questionnaire covered personal background; disease parameters; attitude towards conventional medicine; previous experience with, and knowledge of, complementary therapies; expectations concerning the forthcoming treatment; health-related habits; personality traits; and social support. RESULTS: Optimistic attitudes towards treatment and a positive appraisal of alternative doctors were frequently stated reasons (80%), as was the disease severity (long duration: 86%; acute progression or imminent surgery: 70%). Previous successes with complementary therapies, however, ranked relatively low (53%). Negative opinions concerning conventional therapies and conventional doctors' treatments were mentioned by 68% of the patients. Many patients felt themselves to be under considerable psychologic stress (74%). A majority (73%) was well informed about complementary therapies, and 65% were curious about the forthcoming therapies. Sixty-eight percent (68%) indicated good health behaviors. Fewer patients mentioned contemplative and/or religious attitudes (44%) or lack of social support (25%). Age primarily accounted for variations in the ranking weights of the two subgroups. The specific type of complementary medicine was of minor influence. In 14 out of 21 personality dimensions, the current patient group showed significant deviations from the healthy reference, which is in good agreement with findings from conventionally treated patients.

Adolescent↗
PubMed1999

[In vitro interaction of selegiline, riboflavin and light. Sensitized photodegradation of drugs. I].

Selegiline (Deprenyl, Jumex, Movergan etc.) is primarily used in the therapy of Parkinson's disease due to its neuroprotective, antidepressive and oxidative stress-preventing activities. Its prime effect is based upon the inhibition of the monoamine oxidase enzyme (MAO-B). The cofactor of this flavoenzyme is riboflavin (vitamin B2). Riboflavin, on the other hand, is an effective photosensitizer, with the capacity to promote the photodegradation of molecules (drugs, biological systems) which are otherwise stable against daylight. It has been studied whether this property of riboflavin is expressed against selegiline as well. This experiments proved that in the presence of riboflavin, both daylight and the light of daylight-lamps are sufficient to significantly decompose selegiline. The major decomposition product is methamphetamine.

Drug Interactions↗
PubMed1999

Expression of aquaporin 1 (AQP1) water channels in human labial salivary glands.

Aquaporin (AQP) water channels are widely expressed in the membranes of fluid-transporting epithelia. Despite the fact that salivary glands are the site of considerable water movement, relatively little is known about the role of aquaporins in human salivary glands. We have examined the expression of AQP1 in human parotid, sublingual and labial salivary glands. Total RNA was extracted from glandular tissue obtained from surgery or biopsy. The presence of AQP1 mRNA was demonstrated in each of the three glands by RT-PCR using primers specifically designed for human AQP1. The PCR product from the labial gland RNA was further amplified with nested primers and the sequence confirmed by automated fluorescent DNA sequencing. The cleaned first PCR product from these glands was then used as a 32P-labelled hybridization probe in a Northern analysis which confirmed the presence of significant amounts of AQP1 transcript in all three glands. AQP1 expression was also demonstrated in cryosections of human labial glands by immunohistochemistry using peroxidase-linked antibodies. Antibody labelling was most prominent in the capillaries but was also evident in the basal regions of the labial gland acini, and may therefore be associated with the serous demilunes which are believed to be a significant site of fluid movement.

Adult↗
PubMed1997

[Chemistry of A-2545, an anti-arrhythmia drug candidate. I. Structure elucidation of its main hydrolysis product].

A great number of antiarrhythmic agents with 2,2,5,5-tetramethyl-3-pyrroline (and pyrrolidine)-3-carboxamide structure were synthesized. One of them A-2545 (1) was selected for further investigation aiming the elucidation of its chemical properties. The hydrolysis of 1 was studied, where theoretically seven hydrolysis products might be formed (2-8, Fig.1.). The hydrolysis takes place in aqueous solution of 1. HCl also at room temperature. In alkali-catalyzed process only one main product can be detected by TLC. This hydrolysis product was assigned as phthalamide acid (2) proved by chromatographic, thermic, GC-MS and NMR methods. An interesting behaviour of 2 upon GC-MS investigation (thermic and electron impact) is its recyclisation to 1 at the injector temperature (140 degrees) thus 2 appears in the mass spectrum as it would be A-2545 (Fig. 2. and 3.).

Anti-Arrhythmia Agents↗
PubMed1996

[Ion exchange interactions on silica gel in thin-layer chromatography. IV. Plate investigations by UV spectroscopy].

The properties of silica gel as stationary phase are determined mainly by siloxane, silanol and metal-silanate functional groups. The metals (Na, Ca etc.) getting into the product as trace elements in the course of manufacture may cause the appearance of artefacts. In our previous studies the ion exchange interactions between salt-type analytes and silanol or metal-silanate groups were investigated. It was found in the TLC test of the salts of organic acids and N-bases that the acids and bases are separated from their counter ions and accept protons from or donate to the silica gel layer. In the present paper several analytes of above type have been investigated in situ by remission spectroscopy. These are: phenobarbital, sulfinpyrazone, sulfucetamide, benzoic acid, salicylic acid, (and their Na-salts) and papaverine hydrochloride. Remission spectra were registered from the start spot directly after application and then from the spot after development with the CHCl3EtOH (9 + 1) mobile phase. Based on the difference between the remission spectra of protonated and deprotonated forms of the analytes, the deviations from the initial state could be established. On the basis of the shift of lambda max values one can conclude to the approximate ratio of the protonated (acid) and deprotonated (anion, base) form present in the examined points (middle or edge) of the chromatographic spot. Significantly different protonation states of the analytes were found in the start spots and in the developed spots. These findings are interpreted by the ion exchange interactions between the pharmacon and silica gel. The results provide a deeper insight into the mechanisms of TLC process.

Benzoates↗
PubMed1995

[Methods of thin layer chromatography in quality control (a comparison of the Hungarian and European pharmacopoeias)].

The role of TLC has been enhanced in pharmacopoeial analyses relative to its position in the analytics generally. So it has became on outstanding method in both Hungarian and European Pharmacopoeias. More than 400 purity control prescriptions of the monographs have been evaluated, the limiting tests classified and interpreted by the authors pointing out the similarities and differences. The purpose of the paper was to contribute to the preparation of joining of Hungary to the European Pharmacopoeial Convention.

Chromatography, Thin Layer↗
PubMed1994

Detection of transfusion-associated hepatitis caused by non-A, non-B, non-C flavivirus.

Sera of patients suffering from acute hepatitis, and different forms of chronic hepatitis were found to be reactive to reagents prepared from the yellow fever virus (YF) vaccine strain. Serum samples of 1974 patients were tested, and 133 of them were positive. Hepatitis C virus specific antibodies were absent from the majority of them. The frequency of antibodies to other flaviviruses (tick-borne encephalitis, West Nile) and hepatitis B virus markers was similar to that measured among the population in Hungary positive for any of the surrogate markers of hepatitis infections. Results of both immunofluorescence tests, and Western blots suggest that there is a non-A, non-B, non-C hepatitis virus circulating among the Hungarian population, which possesses antigenic cross-reactivity with the yellow fever virus, but the identity to any of the known flaviviruses could not be verified yet. No history of yellow fever vaccination could be revealed in any of the patients included into this study. The anamnestic data on previous transfusions or surgical operations can be verified only in the case of the half of YFV-positive patients, nevertheless, the sexual transmission seems to be very infrequent. Attempts are continued in order to detect the viral RNA using polymerase chain reaction, and clone cDNA sequences for sequence analysis.

Cross Reactions↗