Biomedical subjects

J Szöllösi

Publications and source records attributed to J Szöllösi.

At least 19 recordsLinked to original sources

PubMed2001

N-Alkane uptake and utilisation by Streptomyces strains.

Streptomyces strains isolated from the Kuwait Burgan oil field were defined as S. griseoflavus, S. parvus, and S. plicatus utilised n-hexadecane, n-octadecane (purified fractions of mineral oil), kerosene, and crude oil as sole carbon and energy sources. The strains were incubated with n-alkanes and increase of the fatty acid content with chain length equivalent to the employed n-alkanes was observed. Signal transducing GTP-binding proteins (GBPs) play an important role in n-alkane uptake in streptomycetes. Specific activators of GBPs increased the uptake of hydrocarbons. Using the hydrophobic fluorescent dye diphenylhexatrien (DPH) as a probe, it was found that the microviscosity of the hydrophobic inner region of the cellular membrane is significantly lower in hydrocarbon utilisers than in non-utilisers. This difference probably reflects differences in the fatty acid composition of the strains. When cultures were grown in n-alkane containing media, electron microscopy revealed that the hydrocarbon utilisers showed less-electron dense areas as inclusions in the cytoplasm. Soil samples inoculated with Streptomyces strains eliminated hydrocarbons much faster than those not containing these strains, serving as control. When inorganic medium was supplied with n-hexadecane-1-14C as sole carbon and energy source, radioactive CO2 was detected. Since streptomycetes have not been used until now for oil elimination, though they are known as abundant soil bacteria tolerating extreme conditions, their possible use for bioremediation of hydrocarbon contaminated soils is discussed.

Alkanes↗

PubMed2001

Screening for human papillomavirus infection in asymptomatic women in Hungary.

BACKGROUND: A multicentre epidemiological survey was carried out in order to determine the prevalence of, and risk factors for, persistent cervical human papillomavirus (HPV) infection in women in Hungary. METHODS AND RESULTS: A total of 728 women were examined for the prevalence of HPV. The estimated overall rate of HPV infection was 17%. In univariate analysis the strongest predictors were young age (< or =24 years), unmarried family status, smoking, a pathological Papanicolaou (Pap) smear, having a condyloma and previous gynaecological cancer in the family (age and marital status being the most important predictors). In multiple regression analysis, young age (< or =24 years)(odds ratio = 1.86, 95% confidence interval = 1.19-2.90, P < 0.01), smoking (1.78, 1.17-2.71, P < 0.05), an abnormal Pap smear (6.92, 2.68-17.84, P < 0.001), having a condyloma (4.22, 1.42-12.58, P < 0.01) and living in a region where the unemployment rate is relatively high (1.56, 1.24-2.82, P < 0.01) were associated risk factors for HPV infection. CONCLUSIONS: The prevalence of HPV infection in young women in Hungary is high. Screening for HPV is suggested only in women with an unfavourable gynaecological history who are < or =24 years old.

Adult↗

PubMed2000

Physical proximity and functional association of glycoprotein 1balpha and protein-disulfide isomerase on the platelet plasma membrane.

Platelet function is influenced by the platelet thiol-disulfide balance. Platelet activation resulted in 440% increase in surface protein thiol groups. Two proteins that presented free thiol(s) on the activated platelet surface were protein-disulfide isomerase (PDI) and glycoprotein 1balpha (GP1balpha). PDI contains two active site dithiols/disulfides. The active sites of 26% of the PDI on resting platelets was in the dithiol form, compared with 81% in the dithiol form on activated platelets. Similarly, GP1balpha presented one or more free thiols on the activated platelet surface but not on resting platelets. Anti-PDI antibodies increased the dissociation constant for binding of vWF to platelets by approximately 50% and PDI and GP1balpha were sufficiently close on the platelet surface to allow fluorescence resonance energy transfer between chromophores attached to PDI and GP1balpha. Incubation of resting platelets with anti-PDI antibodies followed by activation with thrombin enhanced labeling and binding of monoclonal antibodies to the N-terminal region of GP1balpha on the activated platelet surface. These observations indicated that platelet activation triggered reduction of the active site disulfides of PDI and a conformational change in GP1balpha that resulted in exposure of a free thiol(s).

Antibodies↗

PubMed1999

Two-dimensional receptor patterns in the plasma membrane of cells. A critical evaluation of their identification, origin and information content.

A concise review is presented on the nature, possible origin and functional significance of cell surface receptor patterns in the plasma membrane of lymphoid cells. A special emphasize has been laid on the available methodological approaches, their individual virtues and sources of errors. Fluorescence energy transfer is one of the oldest available means for studying non-randomized co-distribution patterns of cell surface receptors. A detailed and critical description is given on the generation of two-dimensional cell surface receptor patterns based on pair-wise energy transfer measurements. A second hierarchical-level of receptor clusters have been described by electron and scanning force microscopies after immuno-gold-labeling of distinct receptor kinds. The origin of these receptor islands at a nanometer scale and island groups at a higher hierarchical (mum) level, has been explained mostly by detergent insoluble glycolipid-enriched complexes known as rafts, or detergent insoluble glycolipids (DIGs). These rafts are the most-likely organizational forces behind at least some kind of receptor clustering [K. Simons et al., Nature 387 (1997) 569]. These models, which have great significance in trans-membrane signaling and intra-membrane and intracellular trafficking, are accentuating the necessity to revisit the Singer-Nicolson fluid mosaic membrane model and substitute the free protein diffusion with a restricted diffusion concept [S.J. Singer et al., Science 175 (1972) 720].

Journal Article↗

PubMed1999

[Detection of human papillomavirus infection by the nucleic acid hybridization method (a multicenter study)].

The human papillomaviruses (HPV) are regarded as one of the important agents of cervical carcinoma. A multicentre study was organized to determine the prevalence of HPV in the fertile female population in Hungary. Parallel with the clinical sample collection, a questionnaire interview was performed to acquire data on the life style, socioeconomic status, sexual practice, etc. 1200 women were examined colposcopically and cervix samples were collected for cytology and the detection of HPV DNA. 17.4% of the samples were HPV-infected. 3.9% of the patients had acquired low-risk, and 10.1% 10.2% high-risk HPV types; 3.4% of the women were at the same time infected with both low-risk and high-risk HPV types. Simultaneously performance of cytology and the HPV hybrid capture assay contribute to recognise and treat the precancerous status and risk factors.

Adolescent↗

PubMed1999

Sperm creatine kinase activity in normospermic and oligozospermic Hungarian men.

PURPOSE: Our purpose was to measure sperm creatine phosphokinase (CK) activity, which reflects cytoplasmic retention in immature spermatozoa, in normospermic and oligozospermic Hungarian men. METHODS: A study of 109 randomly selected men in a university-based andrology laboratory was done. RESULTS: CK activity differed between normospermic and oligozospermic men (0.21 +/- 0.02 vs. 1.19 +/- 0.15 CK IU/10(8) sperm; n = 56 and n = 53; mean +/- standard error of the mean, respectively). There was an inverse correlation between sperm concentration and CK activity (r = -0.70; n = 109). However, 28% of men in the range with less than 10 million sperm/ml had normal sperm CK activity (below the mean + 2 standard deviations of the group with greater than 30 x 10(6) sperm/ml), whereas 36% of men in the group with 20-30 million sperm/ml and 5% in the group with greater than 30 million sperm/ml had elevated CK activities, indicating that the incidence of mature and immature spermatozoa in specimens is independent from the sperm concentrations. CONCLUSIONS: The improved facility of sperm CK activity measurements, compared with sperm concentrations, in the assessment of sperm maturity was confirmed in a Hungarian population. The CK measurements aid the selection of the most efficient treatment for couples with male-factor or unexplained infertility, particularly when considering the options of intrauterine insemination, varicocelectomy followed by a waiting period, or ovulation workup/induction in wives of men who are oligozospermic but may have fertile sperm.

Biomarkers↗

PubMed1999

Nonspecific membrane effects of CH-103: hydrophobicity, surface activity and membrane fluidity studies in comparison with propranolol and practolol.

The partition coefficient, surface activity and membrane fluidizing/disordering effects of CH-103, a beta-adrenergic receptor antagonist, were compared to those of propranolol and practolol as reference compounds. Changes in membrane fluidity were followed by measuring the steady-state fluorescence anisotropy of bull sperm cells with 1-[4-(trimethylammonium)-phenyl]-6-phenyl-1,3,5-hexatriene (TMA-DPH) as a fluorescence probe. The octanol/buffer (pH 7.0) partition coefficients for CH-103, propranolol and practolol were 32.9, 5.08 and 0.013, respectively; the surface activity of the compounds decreased in the same order. CH-103 and propranolol significantly increased the fluidity of the membrane in a concentration-dependent manner, whereas practolol reduced fluidity. These physicochemical parameters correlated with the effects of these drugs on rat sarcolemmal Ca2+, Mg(2+)-ATPase, a manifestation of their nonspecific membrane activity. Our results suggest that the physicochemical properties of CH-103, similarly to those of propranolol, are the main determinants of its nonspecific membrane activity.

Adrenergic beta-Antagonists↗

PubMed1998

Physical proximity and functional interplay of the glycoprotein Ib-IX-V complex and the Fc receptor FcgammaRIIA on the platelet plasma membrane.

Although the glycoprotein (GP) Ib-IX-V complex and FcgammaRIIA are distinct platelet membrane receptors, previous studies have suggested that these structures may be co-localized. To determine more directly the proximity of GP Ib-IX-V and FcgammaRIIA, we assessed the effects of anti-GP Ibalpha monoclonal antibodies on FcgammaRIIA-mediated platelet aggregation and on the direct binding of polymeric IgG to human platelets. In addition, we directly examined the proximity of FcgammaRII and GP Ib-IX-V using flow cytometric fluorescence energy transfer and immunoprecipitation studies. Preincubation of platelets with either of two monoclonal antibodies (AN51 or SZ2) directed against GP Ibalpha completely blocked platelet aggregation by polymeric IgG. Similarly, these antibodies totally inhibited platelet aggregation by two strains of viridans group streptococci known to induce aggregation via FcgammaRIIA. In addition, AN51 and SZ2 significantly reduced the binding of polymeric IgG to washed fixed platelets. When assessed by flow cytometry, significant levels of bidirectional energy transfer were detected between FcgammaRIIA and GP Ibalpha, indicating a physical proximity of less than 10 nm between these receptors. This energy transfer was not due to high receptor density, because no homoassociative energy transfer was seen. Moreover, immunoprecipitation of FcgammaRIIA from platelet lysates also co-precipitated GP Ibalpha. These results indicate that GP Ibalpha and FcgammaRIIA are co-localized on the platelet membrane and that this association is not random.

Antibodies, Monoclonal↗

PubMed1998

Intensity-based energy transfer measurements in digital imaging microscopy.

Investigation of protein-protein associations is important in understanding structure and function relationships in living cells. Using Förster-type resonance energy transfer between donor and acceptor labeled monoclonal antibodies we can assess the cell surface topology of membrane proteins against which the antibodies were raised. In our current work we elaborated a quantitative image microscopic technique based on the measurement of fluorescence intensities to calculate the energy transfer efficiency on a pixel-by-pixel basis. We made use of the broad excitation and emission spectrum of cellular autofluorescence for background correction of images. In addition to the reference autofluorescence images (UV background) we recorded three fluorescent images (donor, acceptor and energy transfer signal) of donor-acceptor double labeled samples, and corrected for spectral spillage of the directly excited donor and acceptor fluorescence into the energy transfer image. After careful image registration we were able to calculate the energy transfer efficiency on a pixel-by -pixel basis. In this paper, we also present a critical comparison between results obtained with this method and other approaches (photobleaching and flow cytometric energy transfer measurements).

Antibodies, Monoclonal↗

PubMed1996

[Ovulation induction with adjuvant antiandrogen treatment in Stein-Leventhal syndrome].

Ovulation induction with adjuvant antiandrogen treatment was carried out in 50 cycles of 24 hyperandrogenic anovulatory patients. Besides the clomiphene and gonadotrophin (pure FSH) administration on the bases of antiandrogenic effects of the drugs three treatment groups (dexamethasone, sprinolactone and cyproterone acetate) were established. In 40 cases of 50 cycles ovulation were detected and 11 pregnancies occurred. The authors achieved the highest ovulation and pregnancy rate in the group treated with cyproterone acetate. The highest progesterone and the lowest testosterone levels were measured in the same group. According to our investigations adjuvant antiandrogen treatment with cyproterone acetate advisable in the cases of hyperandrongenic conditions.

Adult↗

PubMed1996

Depletion of intracellular calcium stores facilitates the influx of extracellular calcium in platelet derived growth factor stimulated A172 glioblastoma cells.

Calcium signaling in non-excitable cells is the consequence of calcium release from intracellular stores, at times followed by entry of extracellular calcium through the plasma membrane. To study whether entry of calcium depends upon the level of saturation of intracellular stores, we measured calcium channel opening in the plasma membrane of single confluent A172 glioblastoma cells stimulated with platelet derived growth factor (PDGF) and/or bradykinin (BK). We monitored the entry of extracellular calcium by measuring manganese quenching of Indo-1 fluorescence. PDGF raised intracellular calcium concentration ([Ca2+]i) after a dose-dependent delay (tdel) and then opened calcium channels after a dose-independent delay (tch). At higher doses (> 3 nM), BK increased [Ca2+]i after a tdel approximately 0 s, and tch decreased inversely with both dose and peak [Ca2+]i. Experiments with thapsigargin (TG), BK, and PDGF indicated that BK and PDGF share intracellular Ca2+ pools that are sensitive to TG. When these stores were depleted by treatment with BK and intracellular BAPTA, tdel did not change, but tch fell to almost 0 s in PDGF stimulated cells, indicating that depletion of calcium stores affects calcium channel opening in the plasma membrane. Our data support the capacitative model for calcium channel opening and the steady-state model describing quantal Ca2+ release from intracellular stores.

Becaplermin↗

PubMed1995

ERBB-2 (HER2/neu) gene copy number, p185HER-2 overexpression, and intratumor heterogeneity in human breast cancer.

Amplification of the ERBB-2 (HER-2/neu) gene is accompanied by overexpression of its cell surface receptor product, p185HER-2. Heterogeneity has been observed for both the gene copy number and the level of overexpression of its protein product. To better understand their relationship, correlation between the level of cellular expression of p185HER-2 and ERBB-2 gene amplification was studied in four human breast cancer cell lines (BT-474, SK-BR-3, MDA-453, and MCF-7) and in a primary human breast tumor sample. The relative expression of p185HER-2 was measured by immunofluorescence by using flow and/or image cytometry while correlated DNA analysis was performed on the same cells by fluorescence in situ hybridization to determine ERBB-2 gene and chromosome 17 copy numbers. Marked heterogeneity was observed in both protein expression and ERBB-2 copy number. Despite this heterogeneity, and in accordance with previous studies, the average levels of p185HER-2 expression correlated well with average ERBB-2 gene copy numbers in the four lines examined (r = 0.99). When the relationship between copy number and protein expression was studied on a cell-by-cell basis, p185HER-2 expression correlated with both the absolute number of ERBB-2 gene copies/cell (r = 0.59-0.63) and chromosome 17 copy number (r = 0.45-0.61). It is of interest that there was weak or no correlation between p185HER-2 protein expression and the ERBB-2 copy number:chromosome 17 copy number ratio (r = 0.0-0.25). In more than one-half of cells expressing a high level of p185HER-2, the chromosome 17 copy number was high (two or three times the average copy number), whereas < 2% of an unselected population had a high chromosome 17 copy number. Bromodeoxyuridine incorporation indicated that the S-phase-labeling index was homogeneous across various p185HER-2-expressing subpopulations in the SK-BR-3 cell line. Analysis of the primary breast tumor sample showed results similar to the cell lines, supporting the strong possibility of a mechanistic link among p185HER-2 overexpression, ERBB-2 amplification, and high chromosome 17 copy number.

Breast Neoplasms↗

PubMed1995

Autofluorescence correction for fluorescence in situ hybridization.

Optimal sensitivity of fluorescence in situ hybridization (FISH) requires bright signals and low background fluorescence. Use of locus-specific probes is especially dependent on high sensitivity. Some tissue preparations show high autofluorescence, masking small or dim signals. We have developed a new method for subtracting autofluorescence from digital images on a pixel-by-pixel basis. It is based on the observation that fluorescent labels for FISH have narrower excitation and emission spectra than the chemical components responsible for autofluorescence. Our new approach uses calculation of the ratio of autofluorescence between multiple color images for correction of autofluorescence in each individual image. By subtracting autofluorescence components, we were able to enhance centromeric signals and make previously indistinguishable cosmid signals clearly visible. This image-processing approach to autofluorescence correction may widen the applicability of gene-specific probes in FISH analysis of tumor material.

Artifacts↗

PubMed1995

Role of endocrine factors in male infertility.

On the evidence of physical examination, history, and semen analysis, endocrinological alteration is suspected in the background of infertility in about one third of the husbands of couples consulting a doctor because of childless marriage. The data of 206 male patients have been processed, and in 71 cases the serum FSH, LH, prolactin and testosterone contents were examined. Statistical analysis was performed for the relationship between gonadotropic hormones and testosterone level, and between the sperm motility and the FSH level, the results of which are presented here.

Gonadotropins, Pituitary↗

PubMed1994

Lateral organization of the ICAM-1 molecule at the surface of human lymphoblasts: a possible model for its co-distribution with the IL-2 receptor, class I and class II HLA molecules.

Lateral distribution of the ICAM-1 molecule and its topological relationship (mutual proximity) to the heavy and light chains of class I HLA molecules, HLA-DR and interleukin-2 receptor alpha-chain (IL-2R alpha) were studied in the plasma membrane of HUT-102B2 T and JY B lymphoblastoid cell lines by the technique of flow cytometric energy transfer (FCET). Effects of adherency and treatments with recombinant interferon-gamma or tumor necrosis factor-alpha on the relative expression level of ICAM-1 to the above cell surface proteins were also investigated. While the cytokines did not significantly affect the ICAM-1 level of either cell line, an increased ICAM-1 expression was found on adherent JY cells. The ICAM-1 expression varied significantly with the cell cycle and culture conditions, as well. The statistical analysis of the differences observed in the energy transfer efficiency histograms resulted in a possible model of lateral co-distribution of these proteins in the plasma membrane. These two-dimensional patterns proved to be different for T and B lymphoma lines. ICAM-1 molecules showed a high degree of self-association on HUT-102B2 (T) cells, while they were mainly expressed as monomers on the surface of JY (B) cells. Both cells showed a significant (ca. 30%) difference between densities of the heavy and light chains of class I HLA antigen, suggesting a substantial amount of beta 2-microglobulin free heavy chains on these cell lines. The class I HLA molecules also showed partial self-association, but on both cell lines. The beta 2-microglobulin and the heavy chain of the class I HLA showed strongly different proximities to the IL-2R alpha, HLA-DR and ICAM-1 molecules, indicating that their orientations relative to the other proteins are dissimilar. IL-2R alpha molecules of the HUT-102B2 (T) cells are located mostly in the vicinity of the beta 2-microglobulin. In contrast, the local density of HLA-DR antigens is higher in the proximity of the heavy chain than in the vicinity of the beta 2-microglobulin. The possible functional significance of these protein patterns is also discussed herein.

Antibodies, Monoclonal↗

PubMed1993

Differential effects of spermine and its analogues on the structures of polynucleotides complexed with ethidium bromide.

The interactions of spermine and polyamine analogues with synthetic polynucleotides of various base sequences complexed with ethidium bromide (EB) were investigated using measurements of fluorescence intensity and steady-state fluorescence polarization. Spermine and polyamine analogues displaced some but not all of the EB bound to poly(dA-dT).poly(dA-dT) or poly(dG-dC).poly(dG-dC), suggesting that polyamines may stabilize these polynucleotides in a conformation with reduced affinity for EB. Modifications of the aliphatic backbone of spermine have pronounced effects on its ability to displace EB from poly(dA-dT).poly(dA-dT) but not from poly-(dG-dC).poly(dG-dC). Spermine and some but not all of the polyamine analogues caused fluorescence depolarization when they interacted with the complex of EB and poly(dA-dT).poly-(dA-dT). Neither spermine nor any of the analogues, however, induced fluorescence depolarization in the complex of EB with poly(dG-dC).poly(dG-dC) or poly(dA).poly(dT). This suggests that spermine and some spermine analogues induce structural changes specific to alternating A-T sequences.

Ethidium↗

PubMed1992

alpha-Difluoromethylornithine alters calcium signaling in platelet-derived growth factor-stimulated A172 brain tumor cells in culture.

alpha-Difluoromethylornithine (DFMO), an irreversible inhibitor of the polyamine biosynthetic enzyme ornithine decarboxylase, inhibits the growth of brain tumor cell lines and is undergoing clinical trials as a treatment for brain tumors. Platelet-derived growth factor (PDGF) is thought to regulate the growth and development of precursors of both normal and neoplastic astrocytic cells; calcium signaling is thought to play a role in the transduction of PDGF signals. Using laser fluorescence image cytometry, flow cytometry, and spectrofluorometry, we studied the effect of DFMO on the calcium signals induced by PDGF in A172 human glioblastoma cells. Four days of treatment with 5 mM DFMO substantially shortened PDGF-induced calcium signals. The effect was reversed more than 10 h but less than 24 h after putrescine treatment, even though polyamines were repleted 4 h after putrescine and spermidine were added. DFMO did not substantially affect intracellular calcium release or the timing of the opening and closing of plasma membrane calcium channels. These findings support the notion that calcium signaling may be a target for inhibitors of polyamine metabolism.

Biogenic Polyamines↗

PubMed1992

[Treatment of infertility, caused by retrograde ejaculation, using intrauterine insemination with sperm enhanced by the "swim up" method].

The causes and the pathomechanism of retrograde ejaculation are reported by the authors. In their case following the failure of the conservative treatment a successful intrauterine insemination was carried out in the superovulatory monitored cycle by semen are covered from the postcoital urine and washed in Ham-F-10. After an undisturbed twin pregnancy a mature male and a female infant was born using Caesarean section. There is a greater chance for pregnancy if the sperms recovered from the postcoital urine are numerous and if their motility is good.

Adult↗