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Biomedical subjects

M T Szabó

Publications and source records attributed to M T Szabó.

13 recordsLinked to original sources
PubMed1992

Differences and similarities in the sensitivity of lymphocytic and macrophage plasma membrane to deoxycholate.

Human tonsillar lymphocytes separated on nylon wool and rat macrophages showed different sensitivity to deoxycholate (DOC) treatment at a low (0.24 mM, 0.01%) concentration for 3 h. The T cell-enriched fraction was stimulated more readily by PHA whereas the B-cell enriched fraction lost its adherence and a decrease of chromium binding capacity was observed after the detergent treatment. Rat peritoneal macrophages under the same conditions lost their chromium label and lysozyme content, whereas their adherence and phagocytic capacity decreased dramatically without affecting their binding capacity. Higher sensitivity to the detergent was observed in peritoneal macrophages compared to tonsillar lymphocytes when various DOC concentrations were used. These findings proved that this low concentration DOC treatment, at least in macrophages, touched mainly the adhesive proteins and the dynamics of the membrane and not its receptor-associated properties.

Animals↗
PubMed1985

Characteristic biochemical differences in human T and B lymphocytes separated on nylon wool.

T and B lymphocytes from human tonsils were separated on a nylon wool column. T. cells are enriched in the nonadherent, B cells in the adherent fraction. Several enzymes and other markers were tested in separated and non separated lymphocyte populations. Certain enzymes and other properties can be used as T or B lymphocyte markers because of their preferential occurrence and because of the advantages of their estimation (simple, quick methods, objective evaluation). The following characteristics were considered as markers on the basis of our results: (I) acid phosphatase, Na+-K+-activated ATPase, BAEE-peptidase and chromium labeling in T lymphocytes; (II) 5'-nucleotidase, FITC-IgG binding, N-acetyl-D-glucosaminidase, thymidine and valine incorporation in B lymphocytes.

B-Lymphocytes↗
PubMed1984

Kinetics of thymidine entry into tonsillar lymphocytes and its alteration in the presence of a lymphokine.

Thymidine uptake into the acid soluble cell fraction of human tonsillar lymphocytes was studied in vitro. Uptake was linear for 15-20 minutes at low concentrations (less than 1.2 microM) of thymidine. The plot of uptake versus time could be extrapolated to the origin. Value for KM (0.5-0.6 microM) and values for Vmax were determined. In the presence of a lymphokine which inhibited thymidine incorporation into DNA the uptake of thymidine into the acid soluble cell fraction was also inhibited. The decreased uptake could be characterized by an increase in the apparent KM, without the alteration of Vmax. Lymphokines which inhibit thymidine incorporation may influence and regulate in vivo the entry of the exogenous thymidine into the cells.

DNA↗
PubMed1981

Studies on human tonsillar lymphocyte membrane. III. Isolation and characterization of plasma membrane fractions after hypotonic lysis.

Hypotonic lysis was applied for the preparation of lymphocyte plasma membranes. By this method it was possible to separate membrane fractions with a high sialic acid to protein and cholesterol to phospholipid ratio. The plasma membrane fractions had a lower content of endoplasmatic reticulum than the preparations described earlier but were slightly contaminated with DNA. The isolation method proved to useful for the preparation of surface membranes from human lymphocytes

Cell Fractionation↗
PubMed1980

A lymphokine-like factor isolated by deoxycholate from the membrane of human lymphocytes.

1. Membranous protein fractions containing carbohydrates were solubilized from human tonsillar lymphocytes in the presence or basence of deoxycholate. The optimal conditions for the detergent treatment, high solubilized protein yield without cell disruption, temperature and time of the treatment and concentration of the detergent were elucidated. 2. The protein fractions inhibited both the mitogen-activated and the nonactivated DNA synthesis in human lymphocyte targets in vitro but did not affect the uptake of [3H]thymidine. The fractions had a slight effect on the amino acid incorporation into proteins and failed to influence the uptake of amino acids. 3. It is assumed that the investigated membranous proteins are lymphokine-like materials produced continuously by lymphocytes in vivo and are incorporated into the membrane of the cells.

Amino Acids↗
PubMed1978

Effect of released lymphocyte proteins on human lymphocytes in vitro. II. Protein synthesis of nylon-wool separated cells in the presence of proteins derived from lymphocytes.

Protein synthesis of nylon-wool adherent (B) and non-adherent (T) human tonsillar lymphocytes was examined in the presence of three protein fractions precipitated with ammonium sulfate from the medium of the above lymphocytes incubated in vitro for 4 hours. One fraction precipitated with ammonium sulfate at 0--30% saturation was found to inhibit amino acid incorporation into proteins mainly in unseparated cells while the fraction precipitated at 30--70% saturation decreased the rate of protein synthesis in B cells. The fraction precipitated at 70--100% saturation inhibited protein synthesis slightly in T lymphocytes. Protein synthesis in B and T as well as in unseparated cells was also examined in the presence of proteins obtained from the medium of B and T lymphocytes. It is assumed that proteins released by lymphocytes without mitogenic activation in vitro are involved in the mediation of lymphocyte interactions and may be related to lymphokines synthesized and released by activated cells.

B-Lymphocytes↗
PubMed1978

Effect of released lymphocyte proteins on human lymphocytes in vitro.

The effect on lymphocytes and Hep2 target cells of proteins obtained from the medium of human lymphocytes incubated for short times was studied. The supernatants were precipitated and fractionated with ammonium sulfate in three steps. Two protein fractions were found to inhibit protein synthesis in target cells and to increase in vitro release of chromium from prelabelled lymphocytes. The proteins studied may be related to lymphotoxin produced by mitogen-activated lymphocytes. It is assumed that in vitro interactions for short times between different types of lymphocytes may cause the release of proteins. The same proteins play probably a part in the in vivo regulation of the metabolic activity of lymphocytes.

Cell Line↗
PubMed1977

Studies on human tonsillar lymphocyte membranes. I. Isolation and characterization of a membraneous glycoprotein fraction from human lymphocytes.

A microsomal fraction containing high amounts of plasma membrane has been isolated from human tonsillar lymphocytes. The subcellular fractions were characterized on the basis of their chemical composition and enzyme activities. A glycoprotein fraction solubilized by lithium-diiodo-salicylate (LIS) was purified by ion-exchange chromatography. The purified glycoprotein was analyzed by various methods and its carbohydrate content was determined. The glycoprotein contained large amounts of hexoses and sialic acid and this fraction represented 3--4% of the whole plasma membrane protein. The fraction was shown to consist of three individual proteins (4 X 10(4), 4.6 X 10(4) and 4.8 X 10(4) daltons) determined by SDS-polyacrylamide gel electrophoresis.

Carbohydrates↗
PubMed1977

Studies on human tonsillar lymphocyte membranes. II. Biological properties of membraneous glycoprotein fractions derived from human tonsillar lymphocytes.

Microsomal and mitochondrial glycoprotein fractions were isolated from human tonsillar lymphocytes. The microsomal glycoprotein was purified by DEAE-Sephadex chromatography. Yielding three subfractions. The different glycoprotein fractions were studied and characterized in two different ways. The isolated glycoproteins inhibited spontaneous (E) rosette formation. This effect was similar to that exhibited by some immunosuppressive drugs and the inhibitory property was heat-labile. The microsomal and mitochondrial glycoproteins and the DEAE-Sephadex subfractions of the microsomal glycoprotein inhibited the mitogenic effect of phytohaemagglutinin and concanavalin A. This inhibition was much stronger than the effect of monosaccharide haptens (N-acetyl-D-galactose-amine and D-glucose) and may be attributed to the lectin-binding property of the glycoprotein fraction.

Concanavalin A↗
PubMed1976

[Gas chromatographic study of odor and flavor components of dry wine].

6, 12 and 18 months after bottling, 1 sample of the primary wine, 2 samples of tank-fermented sparkling wines (taken at different production phases, i.e., during and after the second fermentation) and 3 samples of bottle-fermented raw champagne were analysed for aroma and flavour components. The samples were extracted with ether-pentane (2:1) and analysed by gas chromatography. 21 components were detected, 9 of which were identified (isopropanol, n-propanol, isobutanol, n-butanol, isopentanol, heptanal, n-hexanal, n-heptanol, isooctanol). There were marked qualitative and quantitative differences in composition between the aroma and flavour components of the primary wine sample and the sparkling wines sample taken during the main phase of the tank-fermenting process. This is essentially attributable to the fermenting activities of the yeasts. On the contrary, the aroma and flavour components of the primary wine sample agreed in quality with those of the sparkling wines sample taken at the end of tank-fermentation. It is concluded from these findings that greater amounts of new components do not form during the second fermentation. On the other hand, aroma and flavour components already present in the primary wine came to the fore by the quantitative increase of certain bouquet components. The comparison of the samples of bottle-fermented sparkling wines revealed, irrespective of slight changes, a clear-cut developmental trend. During the aging process, the contents of isopentanol and of a still unidentified component decreased, whereas those of isobutanol, isopropanol, heptanol and a still unidentified component increased markedly. It is stated that differences in the fermenting process manifest themselves mainly by the ratios of the components. The bouquet components were almost similar for both fermenting processes.

Alcohols↗
PubMed1975

A "cytotoxic" factor released from unactivated human lymphocytes.

A protein mixture named LTx, was released from human tonsillar lymphocytes, when incubated at 37 degrees C in either "individual" or "mixed" cultures. LTx caused a decrease in the incorporation of 14C-labelled amino acids of the target lymphocytes, while the release of 51Cr from labelled target cells increased. Target cells were found to bind the "toxic" protein.

Amino Acids↗