Role of glycine-33 and methionine-35 in Alzheimer's amyloid beta-peptide 1-42-associated oxidative stress and neurotoxicity

Recent theoretical calculations predicted that Gly33 of one molecule of amyloid beta-peptide (1-42) (Abeta(1-42)) is attacked by a putative sulfur-based free radical of methionine residue 35 of an adjacent peptide. This would lead to a carbon-centered free radical on Gly33 that would immediately bind oxygen to form a peroxyl free radical. Such peroxyl free radicals could contribute to the reported Abeta(1-42)-induced lipid peroxidation, protein oxidation, and neurotoxicity, all of which are prevented by the chain-breaking antioxidant vitamin E. In the theoretical calculations, it was shown that no other amino acid, only Gly, could undergo such a reaction. To test this prediction we studied the effects of substitution of Gly33 of Abeta(1-42) on protein oxidation and neurotoxicity of hippocampal neurons and free radical formation in synaptosomes and in solution. Gly33 of Abeta(1-42) was substituted by Val (Abeta(1-42G33V)). The substituted peptide showed almost no neuronal toxicity compared to the native Abeta(1-42) as well as significantly lowered levels of oxidized proteins. In addition, synaptosomes subjected to Abeta(1-42G33V) showed considerably lower dichlorofluorescein-dependent fluorescence - a measure of reactive oxygen species (ROS) - in comparison to native Abeta(1-42) treatment. The ability of the peptides to generate ROS was also evaluated by electron paramagnetic resonance (EPR) spin trapping methods using the ultrapure spin trap N-tert-butyl-alpha-phenylnitrone (PBN). While Abeta(1-42) gave a strong mixture of four- and six-line PBN-derived spectra, the intensity of the EPR signal generated by Abeta(1-42G33V) was far less. Finally, the ability of the peptides to form fibrils was evaluated by electron microscopy. Abeta(1-42G33V) does not form fibrils nearly as well as Abeta(1-42) after 48 h of incubation. The results suggest that Gly33 may be a possible site of free radical propagation processes that are initiated on Met35 of Abeta(1-42) and that contribute to the peptide's toxicity in Alzheimer's disease brain.     

The experimental evaluation of antiradiation effectiveness of beta-estradiol on survival rates and bone marrow hemopoiesis of X-ray irradiated mice

The study was aimed at evaluating the radioprotective effectiveness of beta-estradiol following its prophylactic administration in conditions of acute irradiation. Evaluation of the radioprotective efficiency was performed by studying the 30-day survival rate, life expectancy, the structure of irradiated mice death, the bone marrow hematopoiesis using the method of exogenous colony formation. The prophylactic use of beta-estradiol at doses of 20 and 40 mg/kg 5 days before irradiation has been established to protect the exposed mice against radiation death induced by X-rays at doses LD50-90/30, thus increasing their survival rate by 17-58%, and to favor the reduced expression of post radiation disorders of bone marrow hematopoiesis.     

Production of mycobacterial antigenes merged with cellulose binding protein domain in order to produce subunit vaccines against tuberculosis

Protein genes Ag85A, Esat-6, and Cfp10 of Mycobacterium tuberculosis were sequenced using the database GenBank to implement selection and synthesis of primer pairs of given genes. PCR was used to obtain target amplicons of the genes. Chromosome DNA of M. tuberculosis H37Rv was used as the DNA amplification matrix. The PCR products were obtained using the plasmid pQE6, cloned, and amplified in the Escherichia coli M15 strain. Chimere products containing mycobacterial genes and cellulose binding protein domain (CBD), were obtained using the plasmid treated with restriction endonucleases. CBD fragment obtained using similar treatment of the ptt10 plasmid. The plasmids containing merged sequences of mycobacterial genes-antigenes and CBD were selected. The 3 mycobacterial genes were expressed in the E. coli M15 cells resulting in biosynthesis of corresponding recombinant proteins of expected molecular weight. Concentration of CBD, Cfp10-CBD, Ag85A-CBD, and ESAT6-CBD was 20%, 15%, and 15% total protein, respectively. The resulting chimere proteins provide high affinity for cellulose and high stability. Immobilization of CBD-containing recombinant proteins proceeds as one-stage process providing target protein purification and adsorption on cellulose. The vaccines produced using this technology are inexpensive because of low cost of cellulose sorbents as well as simultaneous use of cellulose for purification and immobilization of protein. Many cellulose preparations are not toxic, biocompatible, and widely used in medicine.     

Comparative Analysis of Genotyping Methods for Bacillus anthracis

Russian Journal of Genetics - Genetic typing of the anthrax causative agent is used in epidemiological investigations of infection outbreaks and serves as a tool for studying the evolution of this...     

Mollusks in the zoobenthos of relict lakes with abnormally high biological production in the eastern European subarctic

Species diversity and density of mollusks have been studied in Vashutkiny Lakes (Bol’shezemel’skaya Tundra, northeastern Europe). These lakes are comparable to northern boreal lakes in mollusk species diversity and density levels. Two hypotheses proposed by Zvereva are analyzed: on the relict origin of the ecosystem of these lakes and on the leading role of intrazonal factors in the formation of their abnormally high level of production. Both hypotheses are confirmed by recent data. The production of these lakes is mainly determined by their flowing regime, which offers intense convective heat exchange between water masses and suprapermafrost taliks under the lakes and leads to the accumulation of summer heat in friable Quaternary sediments, which are widespread in lake depressions. Intense water exchange together with strong wind-induced mixing hinders the stratification of water masses.     

见血封喉乳汁脂溶性成分及其抗氧化活性研究

首次采用气相色谱.质谱联用技术(GC-MS)对见血封喉(Antiaris toxicaria(Pers.)Lesch.)乳汁的脂溶性成分进行了分析,共鉴定了27个化学成分,占其总量的91.7%.用清除DPPH自由基能力的方法测定了见血封喉乳汁脂溶性部位的抗氧化活性,结果显示出一定的抗氧化活性,SC50值为500μg ml-1.