Mechanisms of changes in human hemodynamics under the conditions of microgravity and prognosis of postflight orthostatic stability

The mechanisms of hemodynamic responses to orthostatic stresses and orthostatic stability (OS) of cosmonauts were studied before and after short-and long-term spaceflights (SFs) using orthostatic tests, as well as before, during, and after SFs using ultrasonic methods in tests with exposure to lower body negative pressure (LBNP). The capacitance and distensibility of the veins of the lower extremities were studied using occlusive air plethysmography before, during, and after SFs of different durations. A stay in microgravity has been proved to result in detraining of, mainly, the vascular mechanisms of compensating orthostatic perturbations. It has been established that the decrease in OS under the influence of microgravity is determined by a reduction of the vasoconstrictive ability of large blood vessels of the lower extremities; an increase in venous distensibility and capacitance of the legs; and an impairment of blood flow regulation, which leads to a cerebral blood flow deficit in orthostatic stresses, and of the initial individual OS before the flight. The results of preflight studies of hemodynamics by ultrasonic methods at LBNP and the data of orthostatic tests before SFs make it possible to predict the degree of decrease of OS after an SF proceeding in the normal mode. At the same time, the data of ultrasonic blood flow examination provide more a accurate estimation of OS and make it possible to assess the physiological reserves of hemodynamic regulation and to reveal the loss of regulation capacity even in cases where integrated indices (heart rate and blood pressure) are within the normal ranges.     

Spectral features of amines of 2-phenylbenzazoles upon interaction with DNA

Absorption and fluorescent spectra of various synthetic aminophenyl derivatives of benzoxazole, benzothiazole and benzimidazole have been studied to estimate the efficiency of their binding with DNA. The significance of different functional groups of the fluorochromes for their interaction with DNA was determined, and main demands are formulated to the compounds to be used as potential fluorescent probes for DNA studies.     

Evolutionary changes in the structural and regulatory regions of aminoglycoside-3'-phosphotransferase type I gene of E. coli

To investigate the evolutionary relationships between the aph(3') genes from different plasmids, the nucleotide sequence of the aph(3') gene from the E. coli R plasmid was determined and compared with the known aph(3') genes of Tn903 and Tn4352. Three point mutations in the structural part of the cloned aph(3') gene caused amino acid changes in the enzyme molecule at positions 19, 27 and 48 beginning from the start codon. The structural part of the gene was followed by two stop codons and a long DNA region containing no nucleotide sequences homologous to the sequences of Tn903 or Tn4352. Both the cloned aph(3') gene and Tn4352 were limited on the left by the spacer sequence and the insertion sequence IS176. Twenty one base pairs deletion abolished the -35 sequence of the promoter suggested for the aph(3') gene of Tn4352 and resulted in formation of a fusion promoter utilizing the -35 box of IS176 and the -10 box of the aph(3') gene. The distance between the -35 and -10 sequences changed from 18 to 17 bp. Changes in the cloned aph(3') gene and the flanking DNA regions resulted in formation of a new promoter and loss of the right IS176 element.     

Comparative multifactorial analysis of combined administration of injection and peroral forms of an antibiotic with a microbial immunomodulator in experimental anthrax

Comparative efficacy of the use of injection and oral dosage forms of rifampicin in the subtherapeutic doses in combination with peptidoglycan , an immunomodulator of microbial origin, was studied in respect to experimental anthracic infection with application of multifactorial analysis. It was shown that the antibiotic and immunomodulator had a pronounced synergistic effect. Polynomial statistic models were developed and nomograms or equal level curves defining the survival rate and average life-span (ALS) of the experimental animals within a wide range of the antibiotic and immunomodulator doses and the peptidoglycan dosing time were plotted. The combined use of the injection rifampicin in the subtherapeutic doses and the immunomodulator provided a significant increase in the survival rate and ALS, whereas the use of the oral antibiotic in combination with the immunomodulator increased only the ALS and not the survival rate. Multifactorial analysis proved to be an optimal methodical approach to comparative study of various antibiotic dosage forms used in combination with immunomodulators under experimental conditions.     

Polymorphism of a tumor ce-l population and selection processes. IV. The effect of dibunol and nitrosourea on the variability of Ehrlich-I. Ch. Ph. ascitic strain tumor cells]

A study was made of the effect of dibunol and methyl-N-nitrosourea (MNU) on two tumor cell subpopulations of the Ehrlich-I. Ch. Ph. ascites strain, one of which is characterized with A + B + 2C and A + D + 2C--markers and the other one--with A1 + A2 + 2B + D + C markers. Dibunol that belongs to the class of inhibitors of free-radical processes was shown to bring about changes in cell subpopulations, the mode of changes depending on the dose and regime of treatment. The effect of MNU on the population resulted predominantly in the accumulation of cells with various chromosome aberrations. At early stages of tumor progression, aberrations were more pronounced in cells with marker chromosome "A" than in the cells with 44 chromosomes and markers A1 + A2 + 2B + D + C.     

Interferonogenic and antiviral activity of the double-stranded replicative form of phage f2 RNA in tissue culture and on animals]

Biological activity of a new natural interferon inductor, the replicative RNA form of phage f2 (RFf2) was studied. A possibility of using RFf2 for production of highly active interferon under conditions of superinduction providing an increase in the interferon yield by to 256--512 times as compared to the control samples was shown. The protective interferonogenic and antiviral effect of RFf2 in mice infected with Semliki forest virus (SFV) and tickborne encephalitis virus (TBEV) was studied on administration of the inductor by various routes. It was found that intraperitoneal administration of RFf2 in a dose of 10 gamma per a mouse protected the infected animals from death. It was accompanied by production of up to 1280 units/ml of interferon in the blood serum of the animals. Maximum protection of the animals from death under conditions of the experiment (80 per cent on infection with SFV and 65 per cent on infection with TBEV) was observed when the preparation was administered twice: 4 hours after the infection. Combined use of RFf2 with chemotherapeutics (rimantadine) increased the protective effect both in the tissue culture and in vivo.     

Fungal Deterioration of Barrier Concrete used in Nuclear Waste Disposal

Fungal biogeochemical activity over a long-term scale may have negative environmental consequences for the management of barrier materials used in nuclear waste disposal. Fungal deterioration of barrier concrete was studied in microcosms simulating a heterogeneous environment with an external source of nutrients for the fungi. Fungi successfully colonized barrier concrete, generally avoiding granite aggregates, and biochemically (by excretion of protons and ligands) and biomechanically deteriorated the concrete. Fungi dissolved the cement matrix leaching structural elements and accumulating them within the fungal biofilm and associated microenvironment. Oxalate-excreting Aspergillus niger formed abundant calcium oxalate crystals on the concrete and encrusting fungal hyphae.     

Multifactorial study of the combined effect of rifampicin and microbial peptidoglycan in experimental plague infection

The combined effect of rifampicin and a microbial peptidoglycan was studied in multifactorial experiments on noninbred mice with plague infection. The effect of rifampicin and the immunomodulator was shown to be synergistic. The results of the multifactorial experiments provided designing of polynomial statistic models of the second order characterizing the animal survival rate and mean life-span and plotting of nomograms or equal level lines useful in optimization of the combined therapy parameters.     

The Antitumor Properties of Dinitrosyl Iron Complexes with Thiol-Containing Ligands and S-Nitrosoglutathione in Experiments

Biophysics - Abstract—The antitumor activity of S-nitrosoglutathione, bi- and mononuclear dinitrosyl iron complexes with different thiol-containing ligands such as glutathione,...