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.     

Improvement in the tactics of systematic gamma globulin prevention of viral hepatitis taking the morbidity prognosis into account]

On the example of 4 cites of the RSFSR under conditions of expected epidemic threat a possibility was shown of directed influence on the viral hepatitis A epidemic process of preseasonal gamma-globulin prophylaxis conducted in 90% of "organized" children, aged from 1 to 12 years. The dose used was 0.75 ml of a 10% preparation. The method of Gorky Institute of Epidemiology and Microbiology was used to prognosticate the morbidity. It is recommended to improve the tactics of preseasonal gamma-globulin prophylaxis with consideration to the data of the viral hepatitis prognosis.     

Macrokinetic equations of pH effect on the growth of Actinomyces aureofaciens and biosynthesis of tetracycline]

The effect of pH on the culture respiration rate at different concentrations of glucose in the medium was studied. It was found that the hydrogen ions showed their effect irrespective of the subsrate concentration in the medium. In this connection a type of macrokinetic equations of the effect of pH on the growth and antibiotic biosynthesis was chosen. The constants of the model were determined.     

Modification of Oligopeptides Increasing the Effectiveness of Their Interaction with Interleukin-8 in Human Blood Plasma

Russian Journal of Bioorganic Chemistry - Molecular modeling, which identified several peptide sequences, was carried out in search for compounds capable of reducing the interleukin-8 concentration...     

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.     

Isolation and characterization of cardiac progenitor cells from myocardial right atrial appendage tissue

Resident cardiac stem cells, known as “cardiogenic progenitor cells” (CPCs), are a heterogeneous population of immature cells residing in the myocardium and capable of self-renewal and differentiation into cardiomyocyte-like and vascular-like cells. CPCs are usually isolated by long enzymatic digestion of heart tissue and selection with stem cell markers. However, long exposure to enzymatic digestion and the small size of a myocardial sample significantly hinder acquiring a large number of viable cells. To avoid these problems, we developed a method based on CPC growth ex vivo and subsequent immunomagnetic selection.     

The influence of viruses on bacterioplankton of the offshore and coastal parts of the Barents Sea

The viral and bacterioplankton communities of the Barents Sea were investigated using a combination of methods of electron and epifluorescence microscopy for the first time. The quantitative composition of the communities and the nature of their interactions were also determined. Our study showed that during the summer the abundance and biomass of bacterioplankton reached 0.4–4.0 × 10⁶ cells/mL and 25.09–84.21 mg/m³ in offshore waters and 0.4–1.8 × 10⁶ cells/mL and 19.63–100.19 mg/m³ in coastal waters, respectively. In both regions, the number of viruses (1.7–35.8 × 10⁶ and 14.5–32.4 × 10⁶ particles/mL) exceeded the number of bacteria by 2–31 and 13–60 times, respectively; the average viral production was 0.7510⁶ and 1.74 × 10⁶ particles/mL/day, respectively. The proportion of infected cells in the total bacterioplankton (7% on average) and virus-induced mortality of bacteria (8%) were much lower in offshore than in coastal waters (14 and 20%, respectively).     

Ultrastructural morphometry of precompacted bovine embryos produced in vivo and in vitro after activation by electric pulse AC/DC

Early bovine precompacted embryos (at 1- to 8-blastomere stage) were analyzed by electron microscopy. The volume density of cellular components was determined by morphometric analysis to quantify the ultrastructure of early bovine embryos produced either in vivo or parthenogenetically after stimulation of oocytes by electric pulse AC/DC. In embryos obtained in vivo, most of cellular volume was occupied by cytoplasm (82.93%). The relative volume of lipids, vacuoles, mitochondria was relatively low (5.46; 5.07; 3.78%, respectively), and the relative volume of Golgi apparatus and cell inclusions was the lowest (1.51%). AC/DC-derived parthenogenotes had a relative high area occupied by vacuoles and lipids (18.68 vs. 14.33%) and a significantly lower relative volume was occupied by cytoplasm (60.63%) when compared with the control in vivo embryos. These observations demonstrated that parthenogenetic embryos had significantly altered ultrastructure, indicating extensive subcellular damages. These findings are discussed from the physiological and functional point of view.