Biomedical subjects

A Srnak

Publications and source records attributed to A Srnak.

5 recordsLinked to original sources

PubMed1994

Diaspirin crosslinked hemoglobin (DCLHb) polymerization.

By employing proprietary polymerization agents possessing specific binding groups and by completing diaspirin crosslinked hemoglobin (DCLHb) polymerization under specific conditions, we have selectively achieved the following objectives: (1) the P50 was adjusted to the physiologic range or left- or right-shifted; (2) the surface of DCLHb was modified ("decorated"); (3) DCLHb was polymerized but not decorated; (4) DCLHb was polymerized and decorated; or (5) DCLHb was site-specifically modified and polymerized.

Amino Acids, Diamino↗

PubMed1992

Synthesis and properties of polymerized, diaspirin cross-linked hemoglobins.

During the course of our studies it became clear that there were therapeutic applications for which a polymeric hemoglobin having an extended half-life in circulation would be appropriate. Therefore, a process for the glutaraldehyde-polymerization of diaspirin cross-linked hemoglobin (DCLHb) was developed and used to prepare glutaraldehyde-polymerized DCLHb (GP-DCLHb) in lactated Ringer's solution in sufficient quantities for biological testing. Both isovolemic exchange-transfusion and "top-load" studies (rats; primates and swine, respectively) were completed in which a broad spectrum of physiologic, histopathologic and analytical parameters were monitored and assessed. In general, GP-DCLHb in lactated Ringer's solution was well-tolerated physiologically. When compared to DCLHb, GP-DCLHb offers the advantages of reduced renal clearance of hemoglobin and an extended half-life in circulation. GP-DCLHb has the disadvantages that (1) glutaraldehyde is an ineffective virucidal agent under the conditions of the polymerization reaction and a separate virus inactivation step is required; (2) low-endotoxin (LAL-negative) GP-DCLHb solutions are pyrogenic (rabbits); and (3) unusual deposition of hemoglobin-containing material in the small arterioles of the liver and kidney (rats) was sometimes seen even after a period of time (2 weeks) during which treatment-related organ pathologies are usually resolved, a finding peculiar to GP-DCLHb among the various hemoglobin derivatives we have tested.

Animals↗

PubMed1985

Control of Oxidative Sulfur Metabolism of Chlorobium limicola forma thiosulfatophilum.

A metered blend of anaerobic-grade N(2), CO(2), and H(2)S gases was introduced into an illuminated, 800-ml liquid volume, continuously stirred tank reactor. The system, described as an anaerobic gas-to-liquid phase fed-batch reactor, was used to investigate the effects of H(2)S flow rate and light energy on the accumulation of oxidized sulfur compounds formed by the photoautotroph Chlorobium limicola forma thiosulfatophilum during growth. Elemental sulfur was formed and accumulated in stoichiometric quantities when light energy and H(2)S molar flow rate levels were optimally adjusted in the presence of nonlimiting CO(2). Deviation from the optimal H(2)S and light energy levels resulted in either oxidation of sulfur or complete inhibition of sulfide oxidation. Based on these observations, a model of sulfide and sulfur oxidases electrochemically coupled to the photosynthetic reaction center of Chlorobium spp. is presented. The dynamic deregulation of oxidative pathways may be a mechanism for supplying the photosynthetic reaction center with a continuous source of electrons during periods of varying light and substrate availability, as in pond ecosystems where Chlorobium spp. are found. Possible applications for a sulfide gas removal process are discussed.

Journal Article↗

PubMedDate not supplied

Surface modification of diaspirin cross-linked hemoglobin (DCLHb) with chondroitin-4-sulfate derivatives. Part 1.

Synthetic methodology was developed for the preparation of chondrotin-4-sulfate reagents that could be specifically attached to the surface of diaspirin cross-linked hemoglobin (DCLHb), a chemically stabilized human hemoglobin. The surface-modified hemoglobin solutions had a significantly higher colloidal osmotic pressures (COP) than DCLHb. The P(50) of the modified DCLHb was dependent upon the reactive end group of the chondrotin-4-sulfate reagents that was used for the protein modification. Modification of DCLHb with the chondroitin-4-sulfate derivatives containing the maleimide end group 23 provided a hemoglobin with a P(50) value of 23 mmHg, while the P(50) of hemoglobins prepared from chondroitin-4-sulfate derivatives containing the aldehyde end group 13 and 18 remained unchanged from that of DCLHb.

Aspirin↗

PubMedDate not supplied

Polymerization of diaspirin cross-linked hemoglobin (DCLHb) with water-soluble, nonimmunogenic polyamide cross-linking agents.

Diaspirin cross-linked hemoglobin (DCLHb), a human hemoglobin that is intramolecularly cross-linked between the alpha chains (lysine 99(alpha)(1)-lysine 99(alpha)(2)), was polymerized with a number of water-soluble, nonimmunogenic polyamide cross-linking agents. The degree of polymerization and the oxygen-carrying capacity depended upon the polyamide reagent, the starting concentration of DCLHb, the molar ratio of the polyamide reagent to DCLHb used, the reaction pH, and whether oxy- or deoxy-DCLHb was used in the polymerization reaction.

Aspirin↗