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Biomedical subjects

R Shapira

Publications and source records attributed to R Shapira.

70 records · Page 4Linked to original sources
PubMed1973

Experimental allergic encephalomyelitis in the rat: response to encephalitogenic proteins and peptides.

Lewis rats were used to determine the encephalitogenic activity of myelin basic protein of different species and of 45-residue fragments of basic protein. Basic protein from guinea pigs was more active than that from rats, and the fragments from the two species showed the same order of activity. Bovine basic protein was the least active of the intact proteins, and the respective fragment was inactive. Studies of serum-binding capacity did not support the hypothesis that blocking antibody played a role in this biological variation, whereas consideration of the amino acid sequences of the three fragments suggested that differences in primary structure, operating either at the sensitization or the effector phase of the immune response, could account for the variation.

Amino Acid Sequence↗
PubMed1973

Natural history of alcoholic hepatitis. IV. Glycosaminoglycuronans and collagen in the hepatic connective tissue.

The extractable and nonextractable collagen and glycosaminoglycuronans (GAG) were estimated and characterized in 32 dried, defatted human livers obtained at necropsy. 10 had normal livers. 22 of the 32 livers were from patients who drank in excess: 5 had fatty livers, 7 had alcholic hepatitis, and 10 had cirrhosis. Livers with alcoholic hepatitis or cirrhosis had significantly increased total and 1 N NaCl-extractable collagen. Only alcoholic hepatitis livers had significantly increased Tris-buffer-extractable GAG, but the amino acid composition of these GAG (proteoglycans) was no different from that of normal livers. The major fraction of these GAG had isoelectric pH (pI) </= 3.1 in all livers. Livers with alcoholic hepatitis or cirrhosis had significantly increased nonextractable GAG. The major GAG fraction of all livers was chondroitin-4 or -6-SO(4). Alcoholic hepatitis livers had a significant increase of hyaluronic acid and an unidentified hyaluronidase-resistant GAG. Fatty livers showed no differences from normal ones. The data indicates that alcoholic hepatitis is associated with a significantly increased fibroblast activity, but fatty livers of alcoholics are not. The changes in histologically "inactive" micronodular cirrhosis of alcoholic patients indicate continued activity of fibroblasts in the connective tissue of these cirrhotic livers.

Alcoholism↗
PubMed1971

Biologicl activity and synthesis of an encephalitogenic determinant.

A 45-residue fragment of the basic protein of myelin is encephalitogenic in the rabbit and monkey but relatively inactive in the guinea pig. Synthetic peptides containing the sequence of a tryptic peptide of the fragment Thr-Thr-His-Tyr-Gly-Ser-Leu-Pro-Gln-Lys are moderately encephalitogenic.

Amino Acid Sequence↗
PubMed1971

Purified protoplasmic peptides of mycobacteria: chemical composition of a tuberculin-active glycopeptide.

A tuberculin-active glycopeptide containing eight different amino acids and glucose was isolated from the protoplasm of Mycobacterium tuberculosis. A molecular weight of 4,000 to 5,000 was established by Sephadex gel filtration; other analyses showed a peptide to carbohydrate ratio of 9:1. These observations suggest a tentative composition of 3 to 4 residues of glucose, 12 residues each of aspartic and glutamic acids, 3 residues each of lysine, glycine, and serine, and 1 residue each of arginine, threonine, and alanine.

Alanine↗
PubMed1969

Encephalitogenic protein: structure.

Amino acid sequences of encephalitogenic proteins from bovine cord and rabbit brain are reported. The bovine protein contains 45 residues. The rabbit protein is identical except for two isopolar substitutions, a dipeptide and amino acid deletion. Analysis of this protein and a 140-residue myelin basic protein indicates that the smaller protein is a portion of the larger encephalitogen. The larger myelin protein contains at least two encephalitogenic sites.

Amino Acid Sequence↗
PubMedDate not supplied

Activation of protein kinase C augments evoked transmitter release.

In view of the emerging role of the phosphoinositide system in cellular communication we examined its involvement in quantal-transmitter release, which is a key element in synaptic transmission. Transmitter release is normally activated by an increase in intracellular calcium, achieved either by entry of calcium ions through the presynaptic membrane or by intracellular calcium liberation. One of the targets of the phosphoinositide signalling system is the enzyme protein kinase C (PKC), which can be activated experimentally by tumour promoting phorbol esters, including 12-O-tetradecanoylphorbol-13-acetate (TPA). Such activation of PKC may be implicated in transmitter release in two ways. First, phorbol esters were found to increase secretion and enhance calcium currents; it might therefore be expected that they would increase synaptic transmitter release. But phorbol esters also inhibit the calcium current in dorsal root ganglion neurones. We report that the phorbol ester TPA augments synaptic transmission at the neuromuscular junction by increasing transmitter liberation. Activation of PKC also depends synaptic depression.

Animals↗