Selection of Neuroprotective Therapy in Patients with Chronic Cerebral Ischemia Taking Account of the Synergism of Drug Interactions

Neuroscience and Behavioral Physiology - Objective. To optimize selection of neuroprotective treatment protocols in patients with chronic cerebral ischemia taking account of synergism in drug...     

Excimer fluorescence in lens proteins labelled with N-(1-pyrene)maleimide

Lens proteins labelled with the sulphydryl reagent, N-(1-pyrene)maleimide exhibit pyrene excimer fluorescence around 470 nm. This was found to be associated with both the beta- and gamma-crystallins but not the alpha-crystallins. Disappearance of the 470 nm peak on exposure to denaturants indicates it arose from an intramolecular excimer. This excimer fluorescence provides a new and sensitive tool for monitoring conformational changes in the beta- and gamma-crystallins.     

Quenching of tryptophan fluorescence in bovine lens proteins by acrylamide and iodide

The microenvironments of tryptophan residues in bovine alpha-, beta H-, beta L and gamma-crystallins have been examined using acrylamide and KI quenching of fluorescence. From a consideration of the differential effects of the two quenchers, the quenching efficiencies and spectral changes, it was possible to distinguish tryptophans in different environments and to assign these to specific residues in the sequence. Two classes of tryptophan were identified in gamma-crystallin, one buried and one moderately accessible. The buried class contained tryptophans 42A and 125 which lie in the angles of the wedge-shaped domains of the protein. These residues, which had emission maxima at 326 nm, were not accessible to quenching by iodide. The more accessible residues, emitting at 334 nm, corresponded to tryptophans 64 and 148 which are in the widest part of the wedge-shaped subunit and close to the surface of the protein. The two beta-crystallins were virtually indistinguishable. They contained two buried tryptophans, probably residues 58 and 150, and three close to the surface, residues 81, 84 and 166. The quenching efficiencies for these two classes were lower than those observed with gamma-crystallin. Since the three-dimensional structures of the beta- and gamma-crystallins are probably very similar, this suggests that the polymeric nature of the beta-crystallins is responsible for the decreased accessibility of the tryptophans to the quenchers. alpha-crystallin demonstrated unusually high static quenching which made it difficult to distinguish different classes of tryptophan.(ABSTRACT TRUNCATED AT 250 WORDS)     

Changes in lipid peroxidation and antioxidant system of the brain during early postnatal development in rats

We studied three groups of animals: 10-, 20-, and 90-day-old or adult male rats. This age group corresponded to different periods of brain maturation, i.e., periods of cell growth, intense myelination, and complete maturation of the brain. We found that the formation of products of free radical lipid oxidation decreased during ontogeny, whereas the activity of the antioxidant system increased during maturation. The activity of cytoplasmic superoxide dismutase was lower in the brain of developing animals as compared to the adults. The activity of glutathione peroxidase in the cytoplasm also increased during maturation; however, some decrease in this activity was revealed in the 20-day-old rats. Glutathione peroxidase uses reduced glutathione as a source of H⁺. The content of reduced glutathione increased by 20% during the period studied. The activities of glutathione reductase in the cytoplasmic fractions were significantly higher in comparison with the activities in the mitochondrial fractions in all age groups investigated. The activity of the cytoplasmic enzyme reached its maximum on the 20th day, whereas mitochondrial glutathione reductase decreased its activity at this time point. During maturation, the total contents of nonenzymatic lipid-, and water-soluble antioxidants changed differently. Thus, a decrease in the activities of glutathione-dependent enzymes on the 20th day was accompanied by an increase in the total contents of lipid-soluble antioxidants. The maximal levels of water-soluble antioxidants were revealed on the 10th day of postnatal life.     

A photometric method for the determination of lead in washings

In a set of reactions used in photometric lead detection, the arcenaso III and sodium molibdate reaction was chosen for lead control, the measurement level being 0.1 micrograms/cm2 and the measurement range of 0.1-3 micrograms/cm2. The technique is applicable in presence of Fe+2, Fe+3, Al+3, Sn+4, Ni+2, Cr+2, Cr+6, Cd+2, Co+2, Zn+2.