Biomedical subjects
Publications and source records attributed to L Kovács.
The effect of the media (achiral and chiral ionic liquids) on the stereochemistry of intramolecular 1,3-dipolar cycloaddition reactions of D-galactose-derived omega-unsaturated nitrones, leading to bicyclic isoxazolidines, has been investigated.
BACKGROUND: Hereditary hemochromatosis is considered one of the most common hereditary diseases in population of Caucasian origin. In recent years, a candidate gene for HLA-linked hemochromatosis, HFE, has been cloned, and a single G-to-A mutation resulting in a cysteine-to-tyrosine substitution (C282Y) has been identified in up to 80% of study patients with type 1 hereditary hemochromatosis. The purpose of the paper was to confirm the importance of genetic testing for HFE mutations in making the diagnosis of hemochromatosis and find out a suitable diagnostic algorithm for the indication of this form of diagnostics in patients suspected of hereditary hemochromatosis. PATIENTS AND METHODS: The examination of C282Y mutation was conducted in 500 subjects. The most frequent indications for DNA analysis were hepatopathy of unknown ethiology, liver cirrhosis, diabetes mellitus, bronze skin pigmentation in connection with high serum iron concentration, elevated transferrin saturation and elevated serum ferritin levels. RESULTS: In our group of patients, 29 homozygotes and 75 heterozygotes for C282Y mutation were identified, 10 patients carried both C282Y and H63D mutations of HFE gene (compound heterozygotes), whereas in 386 subjects the mutation was not found. The genotype-phenotype correlation showed that 22 homozygotes had liver affection proved by imaging and/or histologic methods. Except the liver disorders, the most common symptoms of these patients were type 2 diabetes mellitus or glucose tolerance disorder (10 patients), arthritis or joint pain (9 patients) and cardiovascular disorders, such as cardiomyopathy (2 patients). Bronze skin pigmentation was present in 9 homozygotes. Transferin saturation values were significantly higher in homozygotes for C282Y mutation as compared to C282Y heterozygotes (p < 0.001), C282Y/H63D compound heterozygotes (p < 0.05) or wild type subjects (p < 0.001) respectively. Also serum ferritin levels were significantly higher in homozygotes for C282Y mutation as compared to C282Y heterozygotes (p < 0.001), C282Y/H63D compound heterozygotes (p < 0.001) and wild type subjects (p < 0.001) respectively. CONCLUSIONS: Our observations confirm that DNA analysis significantly contributes to differential diagnostics of this severe, but in early recognition curable disease. Early detection and phlebotomy treatment prior to the onset of cirrhosis can reduce morbidity and normalize life expectancy. It is readily identified through biochemical testing for iron overload using serum transferrin saturation and genetic testing for C282Y homozygosity. DNA analysis is recommended in patients whose transferrin saturation is 45% or more on a repeated test. General population screening has been waived in preference to targeting high-risk groups such as first-degree relatives of affected individuals and those with secondary iron overload, especially patients with chronic liver disorders and chronic anemia. This screening strategy is likely to continue until uncertainties regarding the natural history of the disease, age-related penetrance, and management of asymptomatic individuals are clarified.
AIM: There is an assumption that ACE I/D polymorphism represents one of the possible genetic factors that might be associated with sports excellence. Recent studies have identified an increased frequency of I allele in elite endurance athletes, long distance runners, rowers and mountaineers. The aim of this study was to test the hypothesis that the ACE I/D polymorphism is associated with enhanced endurance performance. METHODS: We examined this hypothesis by determining ACE I/D allele frequency in 215 marathon runners, 222 half-marathon runners and 18 inline skaters classified by performance (marathon competition results). ACE genotype and allele frequencies were compared with 252 healthy controls. RESULTS: ACE genotype frequency in the whole cohort did not differ from that in the sedentary controls (P < 0.56). However, there was an increase of the I/I genotype incidence amongst successful marathon runners scoring on places from 1st to 150th (P < 0.01). These findings were confirmed in the group of inline skaters, similarly demonstrating an increase of the I/I genotype (P < 0.01). There was no association found between half marathon runners and the ACE genotype (P < 0.59). CONCLUSIONS: An excess of the I allele in long distance runners confirms the association between the ACE I/D polymorphism and endurance sports performance.
OBJECTIVES: The authors have previously identified a peptide of the human muscarinic acetylcholine receptor-3 (m3AChR) as a suitable antigen for the immunodetection of antimuscarinic acetylcholine receptor autoantibodies in primary Sjögren's syndrome (pSS). The aim of this study was to assess the clinical correlations and disease specificity of these antibodies. METHODS: Seventy-three pSS, 40 rheumatoid arthritis (RA), 19 systemic lupus erythematosus (SLE), 14 secondary Sjögren's syndrome (sSS) patients, 22 subjects in whom pSS was suspected but in whom the diagnosis not could eventually be established (suspSS) and 40 healthy subjects were investigated. An enzyme-linked immunosorbent assay system developed by the authors using a 16-mer peptide of the m3AChR (m3AChR(213-228)) in a recombinant fusion peptide form was used as the antigen. RESULTS: Anti-m3AChR(213-228) antibody positivity was observed in 66 (90%) of the pSS patients. The antibody levels correlated positively with the number of extraglandular organ manifestations. Both the mean antibody levels and the occurrence of anti-m3AChR(213-228) positivity were significantly higher in pSS than in the comparison groups. The test discriminated the pSS patients from the various comparison groups with specificities of 65, 68, 71 and 50% for RA, SLE, sSS and suspSS, respectively. CONCLUSIONS: The presence of m3AChR(213-228) antibodies is a common feature in pSS. Although it is significantly more common in pSS than in the comparison groups, anti-m3AChR(213-228) positivity is not exclusive to pSS.
BACKGROUND: Extravascular activation of the coagulation system and consequent fibrin deposition is involved in the pathomechanism of chronic bronchoalveolar inflammatory diseases. The turnover of extravascular fibrin is attenuated by its cross-linking with activated factor XIII (FXIII). OBJECTIVES: Determination of cellular and plasmatic forms of FXIII and their correlation with D-dimer level in the bronchoalveolar lavage fluid (BALF) from healthy children and from children with bronchoalveolar inflammation. PATIENTS AND METHODS: Highly sensitive immunoassays were used for the quantitation of cellular and plasma FXIII and D-dimer in the BALF of children with recurrent wheezy bronchitis and fibrosing alveolitis. BALF was investigated for FXIII-containing cells by flow cytometry. RESULTS AND CONCLUSIONS: In the BALF of controls a low amount of the cellular form of FXIII (FXIII A2) and D-dimer were measured, while plasma FXIII (FXIII A2B2) was absent. Alveolar macrophages represented the single cell population in BALF that contained FXIII. In the BALF of both patients' groups the concentration and the total amount of FXIII A2 was significantly elevated, and plasma FXIII also appeared in the BALF of most patients. The D-dimer concentration was also elevated in the patients' groups and it correlated both with plasma FXIII and neutrophil count. These findings suggest that FXIII A2 is released from activated or injured alveolar macrophages into the bronchoalveolar lining fluid and in bronchoalveolar inflammatory diseases, FXIII A2B2 also leaks out from the capillaries. By cross-linking fibrin and inhibitors of fibrinolysis to fibrin, FXIII might be a key regulator of fibrin turnover in the extravascular compartment.
All possible dimers of the title modified bases with native nucleobases [10 dimers from 3-methylated 6-aminouracils (3sau) and 20 from 5-methyled 6-aminouracils (5sau), respectively have been calculated by ab initio method (Hartree-Fock method, 3 21G basis set). We have found two potential duplexes of 5sau and three possible duplexes of 3sau. Altogether seven dimers containing one or two bifurcating H-bonds have been found. Later on, five triplexes from ten possible calculated dimers have been found. In two of them the amino group of 6-aminouracil moiety takes part in H-bonding and there are H-bonds, too, between the first and third base of the triplexes causing an extra stabilization.
The diastereoselective intramolecular 1,3-dipolar cycloaddition reaction of unsaturated nitrones, derived from methyl alpha-D-glucopyranoside with 2-furaldehyde and 2-(benzyloxy)acetaldehyde has been studied In our pevious studies with 2-furaldehyde, the cycloaddition resulted 3 diastereoisomers in a 3:1:1 ratio. In this article, how the number of the possible isomers generated by 1,3-cycloaddition could be reduced from 4 to 1 when 2-(benzyloxy)acetaldehyde was employed as an aldehyde is shown.
A method was developed for the synthesis of oligonucleotide-cationic peptide conjugates in solution phase by disulfide bond formation. Precipitation was avoided by the easily removable triethylammonium trifluoroacetate (TEATFAc) salt which served at the same time as a buffer of the reaction mixture. The fast and high yielding disulfide bond formation was due to the Npys thio protecting and activating group of Cys. A solution of the free 5-thiol modified oligonucleotide obtained from Poly-Pak purification was used for conjugation.
Rv0802c acetyltransferase is a mycobacterial RNase E-associated protein. 6His and FLAG-tagged acetyltransferase was cloned from Mycobacterium tuberculosis H37Rv, expressed in Escherichia coli and partially purified. It is a 25 kDa protein showing a modest sequence homology with other acetyltransferases. The R-X-X-G-X-G sequence for acetyl-coenzyme A recognition and binding can be found in the molecule.
We have previously shown that the protein kinase C (PKC) system plays a pivotal role in regulation of proliferation and differentiation of the human keratinocyte line HaCaT which is often used to assess processes of immortalization, transformation, and tumorigenesis in human skin. In this paper, using pharmacological and molecular biology approaches, we investigated the isoform-specific roles of certain PKC isoenzymes (conventional cPKCalpha and beta; novel nPKCdelta and epsilon) in the regulation of various keratinocyte functions. cPKCalpha and nPKCdelta stimulated cellular differentiation and increased susceptibility of cells to actions of inducers of apoptosis, and they markedly inhibited cellular proliferation and tumor growth in immunodeficient mice. In marked contrast, cPKCbeta and nPKCepsilon increased both in vitro and in vivo growth of cells and inhibited differentiation and apoptosis. Our data present clear evidence for the specific, antagonistic roles of certain cPKC and nPKC isoforms in regulating the above processes in human HaCaT keratinocytes.
We analyzed the effect of growth hormone replacement therapy (36 months) analyzed at a dose adjusted to maintain serum insulin-like growth factor-I level between the median and the upper end of the age-related reference range on bone mineral density, body composition, and carbohydrate metabolism with respect to gender and age in 20 adult patients (9 women, 11 men, mean age: 43 years, range: 21-61 years). The lumbar and femoral T-score was increased after 12 and after 18 months of therapy respectively in men (p < 0.001 and p = 0.002), but did not changed significantly in women. The increase of femoral T-score was greater in young men (< or = 45 years, n = 6) than old men (> 45 years, n = 5, p < 0.001). Body fat was lower in men than in women after 6 months (p = 0.002). The waist/hip ratio only decreased in women (p = 0.044). The waist circumference decreased in both genders after 6 months of therapy (p < 0.001), but more markedly in females than in males (p < 0.05). The sum of skinfold thicknesses was reduced in males after 6 months of therapy (p < 0.001). Changes in body composition parameters measured were independent of age. The glycosylated hemoglobin increased without sex or age difference after 12 months of initiation of therapy (p < 0.001), but fasting glucose and insulin levels did not change during the therapy. Our results indicate that the effect of growth hormone replacement on bone mineral content in adults is age- and gender-dependent, gender dependent on body composition, but independent of age and gender on carbohydrate metabolism.
We have studied the expressions of various protein kinase C (PKC) isoenzymes in T cells and monocytes from patients with systemic lupus erythematosus (SLE), in comparison to those of healthy controls and patients with other immunological disorders. As measured by Western blotting, the levels of PKCbeta, delta, eta, epsilon, theta and zeta (but not of PKCalpha) significantly decreased in T cells of SLE patients. In monocytes, however, we observed marked suppressions only in the expressions of PKCdelta, epsilon and zeta but not in the expressions of other PKC isoforms. In vivo corticosteroid application, as well as in vitro steroid treatment of monocytes, elevated the expressions of most isoforms close to normal values; however, the decreased levels of PKCtheta and zeta were not affected by steroid application. These alterations were characteristic to SLE because we could not detect any changes in the PKC levels in mononuclear cells of primary Sjögren's syndrome and mixed connective tissue disease patients. These results suggest that impaired PKC isoenzyme pattern may exist in the T cells and monocytes of SLE patients. Furthermore, the clinically efficient glucocorticoid application in SLE can increase the expression of some members of PKC system.
SmpB, a small tmRNA binding protein, is essential for trans-translation. 6His and FLAG tagged SmpB was cloned from Mycobacterium tuberculosis H37Rv. It was expressed in Escherichia coli using the T7 promoter-polymerase system. Anti-FLAG M2 agarose was used for its purification. Mycobacterial SmpB copurifies with other proteins. We identified elongation factor EF-Tu in the purified SmpB preparations.
In this case study a fully symbolic design and modeling method are presented for blood glucose control of diabetic patients under intensive care using Mathematica. The analysis is based on a modified two-compartment model proposed by Bergman et al. The applied feedback control law decoupling even the nonlinear model leads to a fully symbolic solution of the closed loop equations. The effectivity of the applied symbolic procedures being mostly built-in the new version of Control System Professional Suite (CSPS) Application of Mathematica have been demonstrated for controller design in case of a glucose control for treatment of diabetes mellitus and also presented for a numerical situation described in Juhász. The results are in good agreement with the earlier presented symbolic-numeric analysis by Benyó et al.
We analyzed 30 peripheral blood stem cell transplantations (PBSCT) from 25 human leukocyte antigen (HLA) matched sibling donors (MSD) and 4 HLA-matched unrelated donors (MUD) in 29 patients, done between November 1996 and March 2003. Patients aged 3 to 17 years underwent allogeneic PBSCT for malignant (16 patients) and non-malignant (13 patients) diseases. Sibling donors aged 3 to 23 years were given granulocyte colony-stimulating factor (G-CSF) 5-10 microg/kg/day for 4 to 5 days. All but one of the 29 donors underwent one single leukapheresis for stem cell collection. The patients received a median of 4.2 x 10(6) CD34+ cells/kg of body weight, they all engrafted after a median of 13.5 days (range 10-25 days). Acute graft-versus-host disease (GVHD) grade II to IV developed in 11 of 26 MSD transplants and in all 4 patients after MUD PBSCT. Eleven of 27 evaluable patients experienced chronic GVHD. After a median follow-up of 662 days, 20 out of 29 patients (69%) are alive, three of them need systemic immunosuppression for chronic GVHD. Six patients experienced relapse of their underlying malignant disease, one of them still alive in complete remission. Two patients died of grade IV acute GVHD and two others due to an opportunistic infection. Based upon our experience, PBSCT is a feasible and safe method for both pediatric donors and patients. It is associated with rapid engraftment, no greater incidence of acute but a higher incidence of chronic GVHD as compared to bone marrow transplantation (BMT) and therefore suitable mainly for children suffering from malignant diseases.
We studied the effect of growth hormone (GH) replacement on bone mineral density (BMD) and some parameters of bone metabolism, including undercarboxylated osteocalcin (ucOC), an independent predictive marker of fracture risk, which has not been previously determined or compared during GH treatment. Measurements were performed at baseline and after 6, 12, 18 and 24 months of the initiation of the GH therapy in 21 adult patients with GH deficiency. Significant increases were observed in BMD after 1 year at the lumbar spine and after 1.5 years at the femoral neck. Serum total OC and carboxylated (c) OC increased and reached the maximum at 6 months, but the values remained over the baseline at both 12 and 18 months. The ucOC:total OC ratio changed contrarily: it decreased at 6 months, then increased again and reached the baseline level during the next 18 months. Serum calcium (Ca), phosphate (P) and total alkaline phosphatase (ALP) levels increased after 6 months, thereafter the Ca and P values decreased, while the total ALP remained elevated until 12 months. Serum parathormone decreased at 12 months and increased again thereafter. GH replacement therapy is associated with improvement of ucOC, a marker of fracture risk, which in addition to the increase of BMD, might contribute to the beneficial effect of GH replacement therapy on bone metabolism.
The amplitude of the phase dynamic grating is a nonuniform space distributed in photorefractive crystals with nonlocal response as a result of energy transfer between the interacted waves. The dynamical process of grating formation in the case of transmission two- and four-wave mixing is described by the damped sine-Gordon equation that governs the soliton propagation. A stationary soliton solution for the grating amplitude profile was obtained. Experiments on observation of a nonuniform distribution of the grating amplitude through the crystal volume are presented. It is experimentally shown that the changes of the grating amplitude profile in dependence of input intensity ratio match the solutions of the damped sine-Gordon equation in steady state. The diffraction efficiency of energy transfer is determined by the value of the integral under the grating amplitude profile. The soliton profile is altered with changing input intensity ratio of recorded beams. It provides the effect of diffraction efficiency management by changing the half-width and the position of the soliton. The theory predicts a multisoliton behavior in reversible media with strong amplification gain that leads to auto-oscillations of output wave intensities.
In this study, we expressed rat vanilloid receptor 1 (VR1) in various heterologous expression systems using different VR1-encoding vectors, and examined how the VR1 agonists capsaicin and resiniferatoxin affected intracellular calcium. Our results clearly show that the magnitude and kinetics of response as well as the extent of tachyphylaxis differ markedly between systems. Using green fluorescent protein-tagged VR1, we show that much of the VR1 is localized to intracellular membranes. Consistent with this localization, VR1 agonists are able to liberate calcium from intracellular stores in the absence of extracellular calcium. As with other parameters of response, the three expression systems differ in the degree to which, in the absence of extracellular calcium, capsaicin and resiniferatoxin can liberate calcium from the intracellular stores. Our findings emphasize the influence of the expression system on characteristics of the response of VR1 to its ligands and the need for caution in extrapolating such results to other settings.