Organization of reflex sympathetic influence on rate and force of cardiac contraction]

In acute experiments on 21 cats it was proved that the change of afferent impulse on vagus nerves by means of either freeze-block or electrostimulation of their central ends results in differential reflex influences on rhythm and force of the cardiac contractions caused by sympathetic nervous system. The cut of the lower cardiac nerves may cause 'break-up' of the observed reflex, removing or inverting its ino- or chronotropy component. The given phenomenon was revealed in the experiments with high arterial pressure and with absence of tonic chronotropy influences of the left lower cardiac nerve.     

Elemental distribution in striated muscle and the effects of hypertonicity: Electron probe analysis of cryo sections

A method of rapid freezing in supercooled Freon 22 (monochlorodifluoromethane) followed by cryoultramicrotomy is described and shown to yield ultrathin sections in which both the cellular ultrastructure and the distribution of diffusible ions across the cell membrane are preserved and intracellular compartmentalization of diffusabler ions can be quantitated. Quantitative electron probe analysis (Shuman, H., A.V. Somlyo, and A.P. Somlyo. 1976. Ultramicros. 1:317-339.) of freeze-dried ultrathin cryto sections was found to provide a valid measure of the composition of cells and cellular organelles and was used to determine the ionic composition of the in situ terminal cisternae of the sarcoplasmic reticulum (SR), the distribution of CI in skeletal muscle, and the effects of hypertonic solutions on the subcellular composition if striated muscle. There was no evidence of sequestered CI in the terminal cisternae of resting muscles, although calcium (66mmol/kg dry wt +/- 4.6 SE) was detected. The values of [C1](i) determined with small (50-100 nm) diameter probes over cytoplasm excluding organelles over nuclei or terminal cisternae were not significantly different. Mitochondria partially excluded C1, with a cytoplasmic/ mitochondrial Ci ratio of 2.4 +/- 0.88 SD. The elemental concentrations (mmol/kg dry wt +/- SD) of muscle fibers measured with 0.5-9-μm diameter electron probes in normal frog striated muscle were: P, 302 +/- 4.3; S, 189 +/- 2.9;C1, 24 +/- 1.1;K, 404 +/- 4.3, and Mg, 39 +/- 2.1. It is concluded that: (a) in normal muscle the "excess CI" measured with previous bulk chemical analyses and flux studies is not compartmentalized in the SR or in other cellular organelles, and (b) the cytoplasmic C1 in low [K](0) solutions exceeds that predicted by a passive electrochemical distribution. Hypertonic 2.2 X NaCl, 2.5 X sucrose, or 2.2 X Na isethionate produced: (a) swollen vacuoles, frequently paired, adjacent to the Z lines and containing significantly higher than cytoplasmic concentrations of Na and Cl or S (isethionate), but no detectable Ca, and (b) granules of Ca, Mg, and P = approximately (6 Ca + 1 Mg)/6P in the longitudinal SR. It is concluded that hypertonicity produces compartmentalized domains of extracellular solutes within the muscle fibers and translocates Ca into the longitudinal tubules.     

Formation of antibiotic 2562 by a culture of the actinomycete, Streptomyces griseovariabilis]

An actinomycetous culture 2562 inhibiting the growth of gramnegative bacteria was isolated from a soil sample. The culture was classified as Streptomyces griseovariabilis. It was found that culture 2562 produced an antibiotic belonging to the group of novobiocin. It consists of 2 components. One of them is identical to chlorobiocin and the other is a minor component of this group. Some parameters of the antibiotic complex production by strain 2562 under submerged conditions were studied. Nutrient media providing the predominant biosynthesis of the first (main) or the second component of the antibiotic were developed.     

The investigation of structure–activity relationship of polyamine-targeted synthetic compounds from different chemical groups

Amino Acids - The polyamine (PA) metabolism is involved in cell proliferation and differentiation. Increased cellular PA levels are observed in different types of cancers. Products of PA oxidation...     

Plasma pharmacokinetics and tissue distribution of L-lysine α-oxidase from Trichoderma cf. aureoviride RIFAI VKM F- 4268D in mice

L-lysine α-oxidase (LO) is an L-amino acid oxidase with antitumor, antimicrobial and antiviral properties. Pharmacokinetic (PK) studies were carried out by measuring LO concentration in plasma and tissue samples by enzyme immunoassay. L-lysine concentration in samples was measured spectrophotometrically using LO. After single i.v. injection of 1.0, 1.5, 3.0 mg/kg the circulating T_1/2 of enzyme in mice varied from 51 to 74 min and the AUC_0–inf values were 6.54 ± 0.46, 8.66 ± 0.59, 9.47 ± 1.45 μg/ml × h, respectively. LO was distributed in tissues and determined within 48 h after administration with maximal accumulation in liver and heart tissues. Mean time to reach the maximum concentration was highest for the liver—9 h, kidney—1 h and 15 min for the tissues of heart, spleen and brain. T_1/2 of LO in tissues ranged from 7.75 ± 0.73 to 26.10 ± 2.60 h. In mice, plasma L-lysine decreased by 79% 15 min after LO administration in dose 1.6 mg/kg. The serum L-lysine levels remained very low from 1 to 9 h (< 25 μM, 17%), indicating an acute lack of L-lysine in animals for at least 9 h. Concentration of L-lysine in serum restored only 24 h after LO administration. The results of LO PK study show that it might be considered as a promising enzyme for further investigation as a potential anticancer agent.

     

Plant virus infection development as affected by heavy metal stress

The work was focused on the investigation of possible dependencies between the development of viral infection in plants and the presence of high heavy metal concentrations in soil. Field experiments have been conducted in order to study the development of systemic tobacco mosaic virus (TMV) infection in Lycopersicon esculentum L. cv. Miliana plants under effect of separate salts of heavy metals Cu, Zn and Pb deposited in soil. As it is shown, simultaneous effect of viral infection and heavy metals in tenfold maximum permissible concentration leads to decrease of total chlorophyll content in experiment plants mainly due to the degradation of chlorophyll a. The reduction of chlorophyll concentration under the combined influence of both stress factors was more serious comparing to the separate effect of every single factor. Plants' treatment with toxic concentrations of lead and zinc leaded to slight delay in the development of systemic TMV infection together with more than twofold increase of virus content in plants that may be an evidence of synergism between these heavy metal's and virus' effects. Contrary, copper although decreased total chlorophyll content but showed protective properties and significantly reduced amount of virus in plants.     

The antitumor effect of magnetic nanodisks and DNA aptamer conjugates

Here we describe a method of forming large arrays (up to 10⁹ pieces) of free magnetic Ni-nanodisks 50 nm thick coated on both sides with layers of 5 nm thick Au. The antitumor effect of the magnetic nickel gold-coated nanodisks and DNA aptamer conjugates was evaluated in vivo and in vitro. Under the influence of rotating magnetic field, the studied nanodisks can cause the death of Ehrlich ascites carcinoma cells.