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Biomedical subjects

V Kéry

Publications and source records attributed to V Kéry.

14 recordsLinked to original sources
PubMed1993

Methyl-alpha-D-mannopyranoside, mannooligosaccharides and yeast mannans inhibit development of rat adjuvant arthritis.

Methyl-alpha-D-mannopyranoside, mannooligosaccharides obtained by acetolysis of yeast mannan, and pure mannans isolated from the cell walls of pathogenic (Candida albicans) and nonpathogenic (Saccharomyces cerevisiae) yeasts were used for treatment of rat adjuvant arthritis. The arthritis was induced by the application of Freund's complete adjuvant into the tail region of rats. The mannose substances were injected into the arthritic rats intraperitonealy at different time intervals. Levels of serum albumin, changes in hindpaws swelling and radiographs were measured in infected rats as variables of the inflammation and destructive arthritic changes. While mannan from C. albicans inhibited both the inflammation and destructive arthritic changes, mannan from S. cerevisiae showed less effect. However, acetolysate of S. cerevisiae mannan as well as simple methyl-alpha-D-mannopyranoside inhibited both inflammation and destructive arthritic changes to a similar degree as mannan isolated from C. albicans. The effect, which is not dose dependent indicates its possible immunoregulatory mechanism. This is the first time a therapeutic effect of simple carbohydrates on rat adjuvant arthritis has been described.

Animals↗
PubMed1992

Ligand recognition by purified human mannose receptor.

In this work we examine the carbohydrate binding properties of human placental mannose receptor (HMR) using a rapid and sensitive enzyme-linked immunosorbent microplate assay. The assay is based on the inhibition of binding of highly purified receptor to yeast mannan-coated 96-well plates. The specificity of ligand binding was inferred from the potency of different saccharides in blocking HMR binding to the mannan-coated wells. The relative inhibitory potency of monosaccharides was L-Fuc greater than D-Man greater than D-Glc greater than D-GlcNAc greater than Man-6-P much greater than D-Gal much greater than L-Rha much greater than GalNAc. The inhibitory potency of mannose increased by two orders of magnitude when linear oligomers were used. Oligomers containing alpha-1-3- and alpha-1-6-linked mannose residues were more inhibitory than those containing alpha-1-2- and alpha-1-4-linked mannoses. Linear or branched oligomannosides larger than three units did not have a significant influence on their inhibitory potency; rather, potency was found to decrease in comparison with oligomannosides with three units. Compared to linear oligomers, inhibition of binding was the best using branched mannose oligosaccharides, alpha-D-Man-bovine serum albumin conjugates, or mannan. A model is discussed in which branched ligand is bound to spatially distinct sites on the HMR.

Binding, Competitive↗
PubMed1992

Urinary glycosaminoglycan excretion in rheumatic diseases.

We used Alcian Blue (AB) and dimethylmethylene blue (DMB) methods to measure glycosaminoglycan (GAG) excretion in the first morning urine specimens of patients with osteoarthritis (OA), ankylosing spondylitis (AS), and rheumatoid arthritis (RA) in different stages of disease. By the AB method, urinary GAG excretion in patients with RA was not different from healthy control subjects. However, the DMB method showed significant differences (in milligrams of GAG per gram of creatinine) for OA (median 25.4, range 14.3-44.0, P less than 0.01, n = 23) and RA patients (median 33.0; range 10.0-147.6; P less than 0.001, n = 63) in comparison with unaffected individuals (median 20.2; range 8.9-41.4, n = 38). We noted a significant difference in urinary GAG excretion between RA and OA patients (P less than 0.01) and between RA and AS (P less than 0.01) patients. The DMB method was further investigated by clinical decision analysis. The DMB method is simple and rapid and may be useful in diagnosing RA by distinguishing between RA and OA or AS.

Adolescent↗
PubMed1991

Treatment of leukemia L1210 and P388 by arabinosylcytosine-polysaccharide conjugates.

Conjugates of 1-beta-D-arabinofuranosylcytosine (araC) with two polysaccharides such as polygalacturonic acid (PGA) and carboxymethylated yeast beta-D-glucan (CMG) were tested for their antileukemic activity in vitro on a L1210 cell line in suspension culture, in soft agar assay and in vivo on L1210, L1210/araC- and P388-leukemia-bearing mice. Both conjugates showed high activity in vitro in soft agar assay, compared with araC. Single administration of PGA-araC or CMG-araC increased the survival time 1.5 x or 1.7 x, respectively, compared with araC in vivo in L1210-leukemia-bearing mice. The conjugates were not active against araC-resistant leukemia line L1210/araC. The marked effect of both PGA-araC and CMG-araC against leukemia L1210 and P388 is probably due to the prolonged release of free araC from conjugates caused by hydrolysis.

Animals↗
PubMed1991

Immobilisation of beta-D-galactosidase from Escherichia coli on cellulose beads and its use for the synthesis of disaccharide derivatives.

beta-D-Galactosidase, isolated from cloned E. coli, was immobilised on cellulose beads via oxidation with sodium periodate, activation by cyanuric chloride, or diazotisation. beta-D-Galactosidase immobilised via azo bonds showed the highest relative activity and thermostability, and was used for synthesis of disaccharide methyl glycosides.

Cellulose↗
PubMed1991

Specific high performance liquid chromatographic determination of the molecular weight and concentration of hyaluronic acid in complex mixtures by labelled hyaluronate binding proteins.

A simple High performance liquid chromatographic (HPLC) method for the specific determination of the molecular weight and concentration of hyaluronic acid (HA) in complex mixtures has been developed. Hyaluronate-binding proteins isolated from bovine cartilage labelled by 125I or fluoresceinisothiocyanate were used as specific markers. The specific binding affinities of the markers were compared and were found to have association constants of 1.6 x 10(7) M-1 and 1.2 x 10(7) M-1 respectively. The HA levels and molecular weight distributions can be easily determined in the range 10-500 ng/mL in complex mixtures by the use of markers, molecular sieving HPLC columns and appropriate detectors. It has been demonstrated clearly that the method is useful for the highly specific determination of the parameters in complex biological samples such as serum and synovial fluids and is recommended for clinical applications.

Animals↗
PubMed1990

[Urinary tract infections caused by Staphylococcus saprophiticus in children].

Staphylococcus saprophyticus was cultured from the urine of a pyelonephritic newborn as well as a 13 years old boy with symptoms of low urinary tract infection. Cefotaxime respectively Penicillin treatment resulted cure in both cases. Staphylococcus saprophyticus may be an important infective agent in children's urinary infections as well.

Adolescent↗
PubMed1990

Factors influencing the activity and thermostability of immobilized porcine pancreatic lipase.

Lipase from porcine pancreas was immobilized on cellulose beads having various degrees of hydrophobicity, by covalent linking and by hydrophobic adsorption. Lipolytic activity was measured in heterogeneous organic-aqueous systems of various hydrophobicities using olive oil as a substrate. The main factors influencing lipase activity were hydrophobicity of the reaction mixture and of the carrier. Carriers with increased hydrophobicity enhanced lipase activity more than less hydrophobic ones. Lipase immobilized covalently on cellulose beads was less active than that adsorbed onto tritylcellulose but was considerably more thermostable.

Animals↗
PubMed1990

Preparation, properties and antileukemic activity of arabinosylcytosine polysaccharide conjugates.

1. Conjugates of 1-beta-D-arabinofuranosylcytosine (araC) with polysaccharides containing carboxyl groups, such as polygalacturonic acid (PGA) and carboxymethylated yeast beta-D-glucan (CMG) were prepared. 2. Activation of the polysaccharidic carboxyl group by isobutylchloroformiate and formation of a peptide bond via 4-NH2 group of araC was used for a coupling reaction. 3. Elementary analysis, u.v. and i.r. spectra confirmed the structures of the conjugates. 4. The conjugates were most stable against the hydrolysis under the mild acid conditions. 5. It was also shown that under the physiological conditions trypsin catalyze the conjugate hydrolysis and the catalytic effect is higher than that of chymotrypsine. 6. It is suggested that trypsin or trypsin-like proteases could participate in the hydrolysis of the conjugates in vivo. PGA-araC and CMG-araC showed 1.5- or 2.5-times higher antileukemic activity than both free araC or polysaccharides.

Animals↗
PubMed1989

Study of the role of tryptophanyl and arginyl residues in the specific binding of 3,5,3'-triiodothyronine to rat liver nuclear receptors.

The role of tryptophane and arginine residues of rat liver receptors for the specific binding of 3,5,3'-triiodothyronine (T3) was studied by chemically modifying the receptor molecule. Soluble T3 receptor fraction was prepared from purified rat liver nuclei and the kinetics of the modification of a tryptophane indol ring of nuclear receptor by N-bromsuccinimide (NBS) in the presence of excess -SH protecting agent was examined. Moreover the kinetics of the formation of N5-(4-oxo-1,3-diazospiro[4,4]non-2-ylidene)-I-ornithine or N7,N8-(1,2-dihydroxycyclohexyl-1,2-ylene)-L-arginine from arginine residue(s) of nuclear receptor by 1,2-cyclohexanedione was investigated. The efficiency of the reactions were followed spectrophotometrically and the modified nuclear receptor fraction separated from chemical modifiers on a Sephadex G-25 column was assayed at pH 8.0 for T3 specific binding. The T3 specific binding was tested by Scatchard plot analysis. No changes in nuclear receptor Ka or MBC were observed after 1,2-cyclohexanedione treatment. Tryptophanyl residue(s) of the receptor molecule may play an effective role in the maintaining the nuclear receptor in a conformation optimal for T3 binding.

Animals↗
PubMed1986

The number and role of histidine residues in the active site of guanyloribonuclease Sa.

The number and role of histidine residues in the active site of extracellular guanyloribonuclease Sa produced by Streptomyces aureofaciens (RNAase Sa) were studied via chemical modification by ethoxyformic anhydride by means of circular dichroism measurements. It was shown that only one of two histidines of RNAase Sa is situated in the active site of the enzyme. Ethoxyformylation of RNAase Sa in the presence of Guo-3'-P, Guo-5'-P and dGuo-5-P, all of them being competitive inhibitors of the enzyme, supported the assumption that an essential histidine residue is bound to the phosphate group in the position 3' of the ribose ring. The circular dichroism measurements of native and modified RNAase Sa and of its complex with Guo-3'-P showed that the modification of the essential histidine residue resulted in alteration of binding of RNAase Sa to Guo-3'-P; histidine thus may play a key role in the formation of such a complex.

Binding Sites↗
PubMedDate not supplied

Rapid determination of immobilized ConA lectin activity.

ConA was immobilized on an epoxy-activated copolymer of 2-hydroxyethyl-methacrylate and ethylene-dimethacrylate and commercially available high-pressure liquid chromatography (HPLC) sorbents Separon HEMA 1000 EL, Separon HEMA 1000 E, and Separon HEMA 1000 EH (Tessek, Prague, CSFR Denmark). Specific, sensitive, and rapid method for determination of immobilized ConA lectin activity was developed. beta-Galactosidase from Aspergilus oryzae oligomannosyl residues was used as specific affinant. After separation of bound and unbound beta-galactosidase, enzyme activity was measured in supernatant and thus immobilized ConA lectin activity was calculated easily. The use of the method for evaluating the properties of immobilized ConA, efficiency of immobilization, specific activity, and thermostability is shown. The method developed could be generalized by using artificially glycosylated enzyme for any lectin.

Aspergillus↗