Biomedical subjects

T Ramasami

Publications and source records attributed to T Ramasami.

21 records · Page 2Linked to original sources

PubMed1989

Chromium(III)-insulin derivatives and their implication in glucose metabolism.

Insulin has been reacted with five chromium(III) complexes that are capable of relatively facile substitution of aquo ligands. The new Cr(III) insulin derivatives have been characterized by means of electronic and infrared spectra, and evidence for major changes in the protein structure, including the state of aggregation, has been presented. Supporting evidence for the arguments favoring the beneficiary role of chromium(III) in glucose metabolism has been obtained using in vivo studies, and it has been shown that insulin derived with Cr(salen) (H2O)2+ is capable of reversing the blood sugar, serum cholesterol, and phospholipids levels to those of normal rats. The results emphasize the dependence of biopotency on the structure of Cr(III) complexes used for derivation of insulin and discount the postulates that Cr(III) serves to assemble insulin and receptor units through metal-sulphur bonding. The influence of Cr(III) on the structural stability and state of aggregation of insulin and their possible role in glucose metabolism is discussed.

Animals↗

PubMed1987

Active site chemistry of lysyl oxidase.

The bimolecular reduction of the Cu(II)-based enzyme lysyl oxidase with two inorganic reductants, tris bipyridylchromium(II) and (1,3,6,8,10,13,16,19)-octaazabicyclo (6,6,6)eicosanecobalt(II) has been examined at various ionic strength and [H+] conditions. The electrochemical properties of the enzyme have also been examined. The results show that Cu(II) is the redox site in the enzyme and has E 1/2 = 0.05 +/- 0.005 V against SCE. The observed rate constants, kobs, for the reduction of the enzyme by either Cr(bpy)32+ or Co(sep)2+ at any concentration of the reductant increased with the ionic strength of the medium. The ionic strength dependence of kobs has been analyzed in terms of the charge of the active site being 1 +.

2,2'-Dipyridyl↗

PubMedDate not supplied

Mercury intrusion porosimetry, nitrogen adsorption, and scanning electron microscopy analysis of pores in skin.

Stability of collagenous matrixes such as skin and leather with respect to changes in their dimensions on heating has long been correlated with degree and type of cross links formed and short-range ordering in angstrom unit scales. Macroscopic dimensional changes may be expected to involve alterations in the long-range order as well as supramolecular assemblies in skin and leather. This study relates thermal shrinkage of skin matrixes with alterations observed in micro-, meso-, and macroporic structures. Changes in the pore structure of skin associated with thermal shrinkage have been studied using nitrogen adsorption and mercury intrusion porosimetry measurements. A comparison of results obtained using both techniques has been made. These results indicate that although the percentage porosity of the matrix decreases, the BET specific surface area increases on shrinkage. An insight into the changes in the pore systems of skin induced by thermal shrinkage has been gained.

Adsorption↗