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Biomedical subjects

J Gergely

Publications and source records attributed to J Gergely.

305 records · Page 17Linked to original sources
PubMedDate not supplied

Characterization of rabbit masseter muscle fibers.

Myosins of histochemically distinguishable single fibers of rabbit masseter muscle--type 1, 2A, 2B, and slow fibers--have been characterized by gel electrophoresis under dissociating (sodium dodecyl sulfate) and nondissociating (inorganic pyrophosphate) conditions, and by analysis of peptide maps of the heavy chains following limited proteolytic degradation. Type 2B fibers contain more LC3 homodimer than type 2A fibers; peptide maps of their heavy chain are different although the two myosins comigrate on pyrophosphate gel electrophoresis. Slow fiber myosin migrates more slowly than fast myosin and has a distinct peptide map. Differences were also found among fibers of the same histochemical type but originating in different muscles. In adductor magnus 2B myosin the LC1 + LC3 heterodimer band is the strongest, while in masseter 2B myosin the heterodimer is the weakest. Statistical considerations suggest that in masseter there is a mechanism preferentially forming the homodimers. More work is needed to determine the mechanism by which phenotypical differences occur among various fiber types in the same muscle and between corresponding fiber types in different muscles.

Adenosine Triphosphatases↗
PubMedDate not supplied

Molecular aspects of muscle contraction and regulation.

Current views regarding some aspects of the contraction of muscle and its regulation are reviewed. Recent work bearing on the segmental flexibility of myosin is related to cross-bridge movements and ATP metabolism in living muscle. Interaction of troponin with calcium, the process that initiates activation of actin-myosin interaction, is discussed in terms of Ca-induced conformational changes and protein-protein interactions.

Actins↗
PubMedDate not supplied

Ca2+ control of actin-myosin interaction.

Some aspects of the Ca2+-regulation of actin-myosin interaction are discussed. Emphasis is placed on Ca2+-induced conformational changes in the Ca2+-binding subunit of troponin that leads to deinhibition of the actin-myosin interactions.

Actins↗
PubMedDate not supplied

Synthesis and functional studies of tuftsin analogs containing isopeptide bond.

In the present paper a new approach is reported, to increase the resistance of tuftsin toward enzymatic cleavage by the introduction of an isopeptide bond into the molecule. The tetrapeptides H-Lys(Thr)-Pro-Arg-OH and H-Lys(Ala)-Pro-Arg-OH, the pentapeptides H-Thr-Lys(Ala)-Pro-Arg-OH, H-Thr-Lys(Thr)-Pro-Arg-OH and H-Ala-Lys(Ala)-Pro-Arg-OH and their For- and Boc-protected derivatives were built up by stepwise elongation of the chain, using conventional solution-phase methods. Preliminary experiments confirmed that from the Lys residue in position 2 of tuftsin the alpha-peptide bond between the Thr and Lys is cleaved with a significantly higher rate by leucine aminopeptidase than the epsilon-peptide bond. Several of the isopeptide derivatives increased to a higher extent the interleukin (IL-1) secretion by monocytes than tuftsin or [Ala1]-tuftsin.

Amino Acid Sequence↗
PubMedDate not supplied

The biological role of immune complexes.

The biological role of immune complexes (IC) is reviewed. The mechanism of IC elimination, the influence of IC composition on their biological properties as well as on their elimination are discussed. The regulatory effect of IC in immune phenomena is briefly summarized.

Antibodies↗
PubMedDate not supplied

The effect of subacute prazosin treatment on hepatic metabolic enzyme system of young and elderly rats.

We have studied cytochrome P-450 content, aminopyrine-N-demethylating activity, serum bilirubin level, in young 10 weeks old and elderly, 14 months old CFY rats grouped according to sex. The effect of the selective alpha 1-adrenoceptor antagonist antihypertensive prazosin was examined in the previously described groups of animals. We could state that neither oxidative nor conjugative reactions of the liver declined with aging. In a subacute 12 days treatment period prazosin has not impaired liver functions.

Aging↗
PubMedDate not supplied

The role of carbohydrates in the IgG binding and suppressive activities of shed human Fc receptors.

IgG Fc receptor (Fc gamma R) shed from human peripheral mononuclear cells and purified by IgG affinity chromatography bound to ConA, Pisum sativum, Ulex europeus and peanut lectins. The soluble Fc gamma R was not absorbed by wheat germ, soyabean, lentil, Sophora japonica or Helix pomotia lectins. Out of 14 different sugars, none interfered with the interaction between IgG Fc and membrane Fc gamma R. These results show that shed Fc gamma R had glucosyl, mannosyl, fucosyl and galactosyl groups, but that these components were not part of the IgG-binding site(s). The shed FcR had IgG-binding factor (BF) activity; it suppressed secondary in vitro antibody production. In accordance with the binding studies, IgG-BF activity could be adsorbed by ConA and PNA, but not by lentil lectins. The presence of 10 mM galactose or alpha-methylmannoside had no influence on biological activity, suggesting that, although present on human shed Fc gamma R, these sugars do not play a major role in its suppressive activity.

Antibody Formation↗
PubMedDate not supplied

[Binding of polypeptide chains of IGG-determining factors using recombination of isolated chains].

The authors, after autologous and heterologous recombination of alkylated and nonalkylated H and L chains of IgG myeloma proteins belonging to different subclasses, studied the sensitivity to papain of reassociated molecules. They found that the coupling of chains by noncovalent bonds is not sufficient for the restoration of papain resistance characteristic of subclasses IgG 2 and IgG 4 and that disulfide bridges between the chains are also necessary for this. The results obtained by them for the heterologous recombination of chains demonstrate the importance of heavy chains to the development of molecular conformation, throwing light upon the possible role of the variable part of L chains in this particular respect. They also discussed the possibility of preferred linkage of light and heavy chains obtained from IgG molecules belonging to the same subclasses and showed that those heterologous chains which are derived from IgG myeloma proteins belonging to the same subclasses preferably link up with each other. The authors, in the light of the results obtained by them, then discuss the importance of "randomness" and "nonrandomness" in the coupling of H and L chains.

Alkylation↗