Isolated water in desiccated microorganisms

The presence of isolated mobile water in dehydrated eukaryotic microorganisms established earlier by NMR has been confirmed by direct chemical registration of this water in the yeast Cryptococcus albidus. This water constitutes several per cent of the dry biomass weight. Apparently, its preservation should be attributed to changes in the permeability of intracellular membranes upon dehydration. The water is released by the cells when they are heated to 150--200 degrees C and the cellular structures containing water are destroyed.     

Study of the conformational mobility of globular proteins in aqueous solutions according to their proton relaxation in a rotating system of coordinates

Measurements of the nuclear magnetization decay in the rotating frame for protons of SA and RNAase proteins in aqueous solutions indicate the dispersion of the relaxation rate for SA protons within the region of correlation frequencies of 10(5)--10(6) s-1. These frequencies are much lower than frequencies of rotational diffusion movements of the SA macromolecules in aqueous solutions. These must be ascribed to internal movement within protein globules due to which the distances between interacting magnetic moments are changed. This conclusion gives direct evidence in favour of existence of conformational mobility in most of the protein globule volume.     

Diversity of the rDNA ITS haplotypes of the nematodes Haemonchus contortus (Trichostrongyloidea, Rhabditida) of the same host

Specimens sampled in Central Mongolia have been examined for the intraspecific polymorphism of the nucleotide sequences of ribosomal DNA internal transcribed spacers (ITS1 + 5.8S + ITS2) of the parasitic nematode Haemonchus contortus. A considerable diversity of haplotypes differing in the nucleotide composition of this DNA region has been observed. The phylogenetic relationships between the haplotypes detected in Central Mongolia and the corresponding sequences from other parts of the nematode distribution area (deposited with the NCBI GenBank) have been analyzed. Significantly different sequences have been found along with the haplotypes already observed in H. contortus or differing from them by one-two nucleotides.     

Elevated oxidative stress in models of normal brain aging and Alzheimer's disease

Age-associated neurodegenerative disorders are becoming more prevalent as the mean age of the population increases in the United States over the next few decades. Both normal brain aging and Alzheimer's disease (AD) are associated with oxidative stress. Our laboratory has used a wide variety of physical and biochemical methods to investigate free radical oxidative stress in several models of aging and AD. Beta-amyloid (A beta), the peptide that constitutes the central core of senile plaques in AD brain, is associated with free radical oxidative stress and is toxic to neurons. This review summarizes some of our studies in aging and A beta-associated free radical oxidative stress and on the modulating effects of free radical scavengers on neocortical synaptosomal membrane damage found in aging and A beta-treated systems.     

Endocytosis of EGF-receptor complexes at various cell cycle stages

Parameters of EGF-receptor complex endocytosis have been studied in the early and late G1 phase and in mitosis. As a model, mouse mammary epithelial cells HC11 were used, whose growth depends on EGF presence in the medium. The Scatchard analysis has demonstrated that the surface receptors are represented by two receptor populations: 4800 high affinity (KD = 10(-11) M) receptors, and 73,000 low affinity (KD = 4.10(-9) M) receptors. Incubation of cells with the growth factor (5 ng/ml) resulted in a decrease in 125I-EGF binding, with its level being low until entering the S-phase. Under these conditions, receptors disposed on the plasma membrane presented a homogeneous population (KD = 8.10(-11) M, 14,000 receptors per cell). No reliable difference was revealed between the EGF-receptor complexes, internalized in early and late G1 phases, in respect to the internalization rate, level of recycling, degradation, and dynamics of compartmentalization. However, endocytosis of EGF-receptor complexes was found to be completely blocked in mitosis at the stage of internalization.     

Antiviral activity of poly(A)-poly(U) duplexes modified with cis-diammine-dichloroplatinum (II)]

Polyribonucleotide duplex poly(A).poly(U) was modified with cis-diammine dichloroplatinum (II) (cis-DDP). It was shown that the antiinfluenza protective activity of the modified duplex in mice increased with the degree of modification (rb) rising up to 0.2. The effect was different from that for poly(I).poly(C) and poly(G).poly(C). The interferon titers in the murine brain increased in parallel with increasing of the antiviral activity. It was assumed that the structural specificity of the poly(A).poly(U) duplex was responsible for the phenomenon and that cis-DDP interaction with N(7) atoms of the adenine heterocycles blocked the "abnormal" Hoogsteen pairing of adenines with uracils. As a result the antiviral activity increased because of lowering the quantity of the intramolecular defects and increasing the length of the regular double-stranded regions.     

The Antioxidant Vitamin E Modulates Amyloid β-Peptide-Induced Creatine Kinase Activity Inhibition and Increased Protein Oxidation: Implications for the Free Radical Hypothesis of Alzheimer's Disease

Amyloid -peptide (A), the main constituent of senile plaques in Alzheimer's disease (AD) brain, is hypothesized to be a key factor in the neurodegeneration seen in AD. Recently it has been shown by us and others that the neurotoxicity of A occurs in conjunction with free radical oxidative stress associated with the peptide. A(1–40) and several other fragments of the A sequence are associated with free radicals in solution that are detectable using electron paramagnetic resonance spectroscopy. These free radicals were shown to attack brain cell membranes, initiate lipid peroxidation, increase Ca²⁺ influx and damage membrane and cytosolic proteins. In AD brain obtained under rapid autopsy protocol, the activity of the oxidatively-sensitive enzyme creatine kinase was shown to be significantly reduced. We reasoned that A-associated free radical-induced modification of creatine kinase activity and other markers of cellular damage might be modulated by free radical scavengers. Accordingly, this study demonstrates that vitamin E can modulate A(25–35)-induced oxidative damage to creatine kinase and cellular proteins in cultured embryonic hippocampal neurons. These results, consistent with the hypothesis of free radical-mediated A toxicity in AD, are discussed with deference to potential free radical scavengers as therapeutic agents for slowing the progression of AD.     

Characterization of antirubella vaccine in an epidemiological trial

The work was aimed at the evaluation of the antigenic activity and reactogenicity of antirubella vaccine, manufactured by the Serum Institute of India, on the basis of the active observation of 373 children. Vaccinal reactions were registered in 8.8% of the vaccinees. Seroconversion after the injection of the vaccine was 100%. The results of the epidemiological trial demonstrated that the Indian antirubella vaccine was faintly reactogenic and had high antigenic activity.     

Cell cycle and formation of active form of oxygen in rodent fibroblasts

Changes in the levels of mRNAs encoding ion transporters (ATP1B1, NHE1, NKCC1), beta-actin, GAPDH, regulators of proliferation and apoptosis (p53, Bcl-2) and kinase hSGK, involved in cell water regulation, were studied using RT PCR in the peripheral human lymphocytes activated with phytohemagglutinin for 4-24 h. The common, "grouped", effect that was found was an increase in the levels of the studied mRNAs after an 8 h activation, sometimes preceded by a delay or slight decrease at the initial stage of 0-4 h. Apart from the common features, some differences were observed in the time courses and amplitudes of the responses of individual mRNAs. The arrangement of the individual mRNA responses in lymphocytes from different donors could differ significantly, thus indicating differential regulation of the studied mRNAs apart from the "grouped" effect. The data obtained confirmed our suggestion that regulation of ion transport at the level of mRNA could be involved in the changes of ion balance at the late stage of lymphocyte activation.