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Biomedical subjects

S Pongor

Publications and source records attributed to S Pongor.

81 records · Page 5Linked to original sources
PubMed1983

Covalent attachment of soluble proteins by nonenzymatically glycosylated collagen. Role in the in situ formation of immune complexes.

The chronic tissue damage associated with long-term diabetes mellitus may arise in part from in situ immune complex formation by accumulated immunoglobulins and/or antigens bound to long-lived structural proteins that have undergone excessive nonenzymatic glycosylation. In this report, we have tested this hypothesis using nonenzymatically glycosylated collagen. Binding of both albumin and IgG averaged four times the amount bound to unmodified collagen. Both albumin and IgG (anti-BSA) bound to nonenzymatically glycosylated collagen retained their ability to form immune complexes in situ with free antibody and antigen.

Antigen-Antibody Complex↗
PubMed1983

A latex agglutination test for lectin binding.

Blood group A + H substance purified from hog gastric mucin was fixed to polystyrene particles by physical absorption to produce a lectin-agglutinable latex. Agglutination of this latex by soybean agglutinin, concanavalin A, and wheat germ agglutinin is specifically inhibited by the respective monosaccharide haptens and is not affected by known noninhibitory sugars. The sensitivity of the assay, a function of particle loading and latex concentration, approaches that of the hemagglutination test. NaCl, NaHCO3, NH4CO3, NH4-acetate, and Tris-HCl up to a concentration of 1 M do not interfere with the test. The latex suspension is stable for several months and can be stored in freeze-dried form.

ABO Blood-Group System↗
PubMed1983

Preparation of high-potency, non-aggregating insulins using a novel sulfation procedure.

The marked propensity of insulin to self-associate into large aggregates causes significant mechanical problems in insulin delivery devices and may also stimulate production of a tissue-amyloid A precursor in some patients. Although conventionally prepared sulfated insulin (SI) resists aggregation, clinical application has been limited by major insulin bioactivity losses that occur during synthesis. To eliminate this problem, insulin sulfation was carried out in the organic solvent dimethylformamide in the presence of condensing agents such as N,N'-dicyclohexyl carbodiimide (DCC) and a sulfate donor. With this new procedure, the degree of sulfation could be controlled over an eightfold range by varying the amount of condensing agent. The bioactivity of these new SI derivatives varied between 78% and 87% of unmodified insulin. Insulin aggregation, induced by passage through a syringe and needle, did not occur with derivatives having two or more sulfate moieties per insulin molecule. Diffusion velocity studies using "non-aggregated" insulin solutions demonstrated that aggregates were present in crystalline zinc and sodium porcine insulin. In contrast, SI having more than 0.5 mole sulfate per mole of insulin dialyzed as it were predominantly in the monomeric form. Results from the studies described in this report now provide the means for selectively designing and preparing specific high-potency, non-aggregating insulins, which may be necessary for optimal use of current and future insulin delivery devices.

Animals↗
PubMed1976

Quantitative determination of methionine in proteins: gas chromatography of methylthiocyanate liberated by cleavage with cyanogen bromide.

A rapid non hydrolytic method was developed for the estimation of methionine residues in peptides and proteins. The method is based on the gas chromatographic determination of methylthiocyanate liberated in the reaction of cyanogen bromide with the methionine residues. In contrast to the amino acid analyzer technique this method allows selective determination of methionine in the presence of methionine sulphoxide and sulphone. It was tested with both purified proteins and protein-containing crude samples (legume seeds) and was compared with different analyzer techniques.

Chromatography, Gas↗
PubMedDate not supplied

Further evidence for the relationship of HIV-1 gp120 V3 loops with Ig superfamily members: similarity with the putative CDR3 region of T-cell receptor delta-chains.

Twenty-five V3 loops of envelope gp 120 extracted from 30 HIV-1 isolates were compared with T-cell receptor (TCR) subunits variable (V) portions using pairwise alignments of 11-residue peptides. The results indicate that, in comparison with random sequences, the analyzed V3 loops, unlike control (unrelated) sequences, display highly significant local similarity with TCR V delta (p approximately 10(-20)). However, pattern-matching searches were performed on a much larger number of V3 loops (484). In particular, selective pattern TR * * * NT * K * I is shared by V delta from human T-cell line KT19E and 230 HIV-1 V3 loops (N-terminal portion). Pattern RA * YT * * * I * G is common for V delta chain isolated from T-cell line DS6 of an immunodeficient patient and 69 V3 loops (C-terminal portion). The presented delta-chain portions of sequence similarity with the V3 loops overlap the putative complementarity-determining region (CDR3), thus possibly indicating functional similarity too.

Amino Acid Sequence↗