Stress-protective effect of the synthetic ACTH-like peptide leucocorticotropin

We found that the tritium-labeled synthetic ACTH-like octapeptide leucocorticotropin corresponding to the 81-88 sequence of the precursor of human interleukin-1alpha ([3H]GKVLKKRR) is bound by the ACTH receptor of rat adrenal cortex with a high affinity and specificity (Kd 2.2 +/- 0.1 nM). This peptide was shown to exert no effect on the adenylate cyclase activity of the membranes of rat adrenal cortex in the concentration range from 1 to 1000 nM. Leucocorticotropin administration three times at doses of 10-20 microg/animal did not change the level of hydroxycorticosteroids (11-HOCS) in the rat adrenal glands in the absence of temperature action. At the same time, the peptide abolishes (at a dose of 20 microg/animal, three times) or significantly decreases (at a dose of 10 microg/animal, three times) the dramatic increase in the 11-HOCS content in the adrenal glands occurring in the case of cold or heat shock. Thus, leucocorticotropin normalizes the 11-HOCS level in the rat adrenal cortex during stress. The stress-protective effect of the peptide is mediated through the ACTH receptor.     

Monolithic stationary phases: yesterday, today, and tomorrow

The history of the development of monolithic stationary phases in chromatography, the modem state of the art, and the prospects for their use are considered.     

Short peptide fragments with antiulcer activity from a collagen hydrolysate

A peptide acidic hydrolysate of collagen (PHC) was obtained under conditions (4 N HCl) ensuring the predominant formation of short peptides, glyprolines. They were separated and their antiulcer activity was studied. Thirty individual peptides with molecular masses of 174-420 amu were isolated from the PHC by HPLC. The PHC was shown to predominantly contain 2- to 4-aa peptides, including PG, GP, and PGP. Experiments on rats demonstrated that, on intragastric administration at a dose of 1 mg/kg, PHC enhances the stability of the gastric mucosa to the action of ulcerogenic factors, such as ethanol and stress, and exhibits a protecting antiulcer effect. Even a lesser dose (0.1 mg/kg), which reduced ulcer area twofold, was effective in the stress model of ulcer formation. The intraperitoneal and intragastric administration of PHC at a dose of 1 mg/kg was found to exhibit a therapeutic effect in the acetate model of ulcer formation.     

The effect of N-stearoylethanolamine on lipid composition of the metastases and conditionally normal lung tissue in mice with Lewis carcinoma

Influence of NSE on lipid composition of metastases and the neighbouring conditionally normal lung tissue in mice with Lewis carcinoma was investigated. The processes of peroxidation in investigated tissues were also studied. It was shown that under the influence of NSE the high level of antioxidant activity in the metastases was decreased, while in the neighbouring conditionally normal lung tissue the catalase activity was increased. The content of the thiobarbituric acid-reactive substances in comparison with animals which were not fed by NSE was decreased. The development of carcinoma was accompanied by significant decrease of cholesterol level and by the increase of unsaturated fatty acids esterified in membrane phospholipids in both the metastases and the neighbouring conditionally normal lung tissue. An analysis of the phospholipid spectra shows that under tumor growth in investigated tissues the high-level lysophosphatidylcholine (LPC) was observed. The content of phosphatidyl choline (PC), phosphatidyl ethanolamine (PE), phosphatidyl serine (PS) was found to be significantly lower than in the lung of intact animals. It was found that administration of NSE to tumor-bearing mice contributed to the increase of cholesterol level, to the decrease of omega-6/omega-3 ratio polyunsaturated fatty acids of total phospholipids. NSE modulated the phospholipid membrane composition in both the metastases and the neighbouring conditionally normal lung tissue.     

Organization of the Karshi virus strain Leiv-2247 Uz genome and its phylogenetic relationships with other representatives of the Flavivirus genus

For the first time, the Karshi virus complete genome sequence has been determined and analyzed in this work. The Karshi virus was attributed to the Tick-borne encephalitis group on the basis of phylogenetic analysis of polyprotein sequencing, as well as partial NS5 of the Flavivirus genus. Comprehensive analysis of the longed to its own cluster, which includes also the Royal Farm virus.     

Role of catalase and superoxide dismutase in the yeast Saccharomyces cerevisiae response to hydrogen peroxide in exponential phase of growth

The role of catalase and superoxide dismutase (SOD) in response of the yeast Saccharomyces cerevisiae to oxidative stress induced by hydrogen peroxide in the middle-exponential phase has been investigated. It was shown that cell survival is significantly decreased after yeast exposure to hydrogen peroxide in the strains defective in cytosolic or peroxisomal catalases. Treatment of the wild-type cells with 0.5 mM H2O2 for 30 min causes an increase in the activity of catalase and superoxide dismutase, but the effect was not observed in all strains investigated. It was also shown that hydrogen peroxide leads to an increase in the activities of both catalases and Cu,Zn-containing SOD. The effect was cancelled by cycloheximide, an inhibitor of protein synthesis.     

EDAS, databases of alternatively spliced human genes

EDAS, a database of alternatively spliced human genes, contains data on the alignment of proteins, mRNAs, and EST. It contains information on all exons and introns observed, as well as elementary alternatives formed from them. The database makes it possible to filter the output data by changing the cut-off threshold by the significance level. The database is accessible at http://www.gene-bee.msu.ru/edas/.     

The in vitro motility assay to study the calcium-mechanical relationship in skeletal and cardiac muscles

In a series of experiments on regulated contractile systems (i.e., in vitro mobile systems with reconstructed thin filaments), the velocities of the movement of a thin filament on the surface covered by either rabbit skeletal or rat cardiac myosin at various concentrations of calcium ions in solution (in the pCa range from 4 to 8) were assessed. The corresponding "pCa-velocity" relationships were plotted, which proved to be of the sigmoid form. It was found that, at a saturating calcium concentration (pCa 4), the velocity of regulated thin filaments was 65% higher than for unregulated ones in the case of skeletal myosin and 87% higher than for unregulated thin filaments in the case of cardiac myosin. It was also found that the Hill coefficient was 1.95 and 2.5 for skeletal and cardiac myosins, respectively. The difference in the Hill coefficients for skeletal and cardiac myosins is discussed in terms of the difference in contribution of cooperativity mechanisms of contractile and regulatory proteins in the regulation of contraction in these types of muscles.     

Transient currents and Ca2+ gradient relaxation in characean algae cells: theory and experiment

Transient Ca2+ and Ca2+-dependent Cl- currents of plasmatic membranes of voltage-clamped Chara corallina freshwater alga cells were studied. Our earlier described method was used for rapid (approximately 10 ms) injection of Ca2+ ions into the cell during the deactivation period of calcium channels following their activation by a positive voltage pulse (injection by "tail" Ca2+ current). This procedure allowed one to determine the amplitude of the Ca2+ component, as well as the amplitude and kinetics of the submembrane Ca2+ concentration-dependent Cl- component for the transient current. Calculations based on the cell model allowing for Ca2+ diffusion, the Ca2+-buffering properties of the cytoplasm, and the nonlinear dependency of iCl on [Ca2+]cyt, as well as the presence of chloroplasts agreed well with the experimentally observed behavior of the transient current. The slow stage of the [Ca2+]cyt relaxation to the resting level (approximately 10(-7) M), related to the functioning of Ca2+-ATPases, was shown to take approximately 10(2) s. We assume this stage to determine the duration of the refractory period after the generation of action potential.     

A study of the inhomogeneity of bilayer lipid membranes by measurements of higher harmonics of transmembrane current

Higher harmonics of alternating current in bilayer lipid membranes caused by sinusoidal voltage applied to the membrane were measured. The bilayer lipid membranes were prepared from diphytanoylphosphatidylcholine in n-decane and n-tetradecane, and measurements were conducted with the aid of an analog-to-digital converter of 16th category. Sinusoidal voltage was formed using a digital-to-analog converter of the 16th category. The dynamic region of measurements was up 90 dB. The results of measurements were used to determine the alpha and beta coefficients of the expansion of membrane capacity C in terms of membrane voltage U C = C0 (1 + alphaU2 + betaU4). We showed in the framework of the electrostriction model that the relation between the alpha and beta coefficients characterizes the inhomogeneity of bilayer lipid membrane with respect to its thickness and Young modulus of elasticity.