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Biomedical subjects

R A Gelman

Publications and source records attributed to R A Gelman.

At least 37 records · Page 2Linked to original sources
PubMed1976

The effect of a strongly-interacting macromolecular probe on the swelling and exclusion properties of loose connective tissue.

Poly(L-lysine), a cationic polypeptide known to undergo specific interactions with acid mucopolysaccharides, is used as a macromolecular probe in an investigation into the structure of loose connective tissue. The polypeptide apparently binds, via an electrostatic mechanism, to the mucopolysaccharide component of the tissue, leading to a reduction in the swelling of the tissue. The polypeptide does not, however, have a deswelling effect on the tissue; the ultimate reduction in swelling is influenced by the absolute amount of polybase which enters the tissue during the swelling process. Dextran 2000 is found to have a dwelling effect on the tissue which is independent of the action of the polypeptide; this is suggestive of a large degree of independence between the collagen network and the mucopolysaccharide-containing matrix. The polypeptide, moreover, causes a reduction in the excluded volume of the tissue.

Arginine↗
PubMed1975

On the role of sialic acid in the rheological properties of mucus.

The importance of sialic acid in the rheological properties of mucus has been investigated. Both bovine cervical mucus, which is a gel, and the structural glycoprotein derived from it were studied before and after treatment with neuraminidase which selectively cleaves terminal sialic acid residues. The storage modulus, viscosity and circular dichroism spectrum were all essentially changed after removal of the sialic acid. These results would indicate that removal of sialic acid does not affect the physical structure of the glycoprotein and it is concluded that sialic acid has no significant role in the rheological properties of cervical mucus.

Animals↗
PubMed1975

Permeability of the blood-brain barrier to long-chain alcohols from plasma.

Cis-9-octadecenyl alcohol was fed as a dietary supplement to adult male rats for 7 and 14 days. At the end of these feeding intervals, lipids were extracted from brain and liver. The neutral lipids were analyzed for free and esterified long-chain alcohols and alkyl and alk-1-enyl glycerols. Total lipid phosphorus, alkyl acyl and alk-1-enyl acyl phosphoglycerides were determined in the phospholipid fraction. A marked change was observed in these lipid types in the liver, but not in the brain. In liver the free and esterified long-chain alcohols increased threefold following feeding of the dietary supplement. Feeding cis-9-octadecenyl alcohol had no effect on the neutral alkoxy lipids of liver but resulted in an approximately three- to eightfold increase in the ionic alkoxy lipids.

Animals↗
PubMed1974

Interactions of an intact proteoglycan and its fragments with basic homopolypeptides in dilute aqueous solution.

The interactions between a proteoglycan and cationic polypeptides have been investigated by the use of circular-dichroism spectroscopy. The interaction produces an induced conformational change for poly(l-arginine) and poly(l-lysine), similar to the effects previously reported for mucopolysaccharide-polypeptide mixtures. For bovine nasal septum proteoglycan, the interactions are similar to those for chondroitin 4-sulphate, which comprises approximately 63% of the total polysaccharide. The results also suggest that the interactions produce a conformational change in the protein core. Similar studies for the Smith-degradation product show that the protein core can adopt a substantial alpha-helical content and is capable of interactions with poly-(l-arginine). The interactions for chondroitin sulphate ;doublets' are significantly different from those for the separated chains, indicating that the arrangement of the polysaccharide side chains in pairs (and larger groups) along the protein backbone contributes to the interaction properties of the intact proteoglycan.

Animals↗
PubMed1972

Natural occurrence of free fatty aldehydes in bovine cardiac muscle.

Free fatty acids, aldehydes, alcohols, and 1-O-alkyl and alk-1-enyl glycerols were identified and quantified in lipid extracts from bovine cardiac muscle. Although a number of components present in the free fatty aldehydes were also noted in the fatty chains in the 1-O-alk-1-enyl glycerols, a direct qualitative similarity did not exist as would be expected if the free fatty aldehydes were artifactual in origin. Also, a qualitative similarity did not exist between the fatty chains of the 1-O-alkyl and alk-1-enyl glycerols. This latter observation would suggest a mechanism other than biodehydrogenation of the alkyl ethers for the origin of the alk-1-enyl glycerols. Free fatty aldehydes were distributed evenly between the 105,000 g supernatant and particulate fractions of cardiac muscle, while the 1-O-alk-1-enyl glycerols were associated primarily with the particulate fraction. Free fatty alcohols were noted only in the supernatant fraction, while the 1-O-alkyl glycerols were present in both fractions.

Aldehydes↗