A study of dilute aqueous solutions of humic acids by scanning microcalorimetry

It has been found by reversed-phase chromatography that humic acids obtained from vermicomposts of different duration of vermicomposting consist of a hydrophilic and a hydrophobic fractions, the hydrophobic fraction having a substantially lower content of charged, probably carboxylic, groups. A change in the sign of the temperature dependence of the heat capacity of dilute aqueous solutions of humic acids at ∼58°C has been found by differential scanning microcalorimetry, which indicates an increase in the hydration of hydrophobic groups. A jump-wise increase in heat capacity in the temperature range from 86 to 90°C was also found, which is perhaps due to hydration of hydrophobic groups in the interior of “micelles“, because of “devitrification” of the hydrophobic nucleus of micelle-like structures. It was shown that increasing the duration of vermicomposting leads to an increase in the relative content of the hydrophobic fraction of humic acids and in the cooperativity of the thermodynamic transition, which manifests itself as the jump of heat capacity, which probably results from the increase in the “micelle” size.     

Surface antigen structure of Neisseria meningitidis. I. The isolation of a serotypic antigenic complex of N. meningitidis strain B16B6 by direct detergent treatment and its immunochemical characteristics

The method for obtaining a serotyping antigenic complex from N. meningitidis B16B6 by their direct treatment with the mixture of detergents (0.5% sodium desoxycholate and 0,5% cholic acid in the proportion 1 : 1) in 0.5 M KCl solution is proposed. Such treatment has been found to increase the yield of the preparation in terms of protein more than 4 times in comparison with earlier methods for obtaining serotyping antigens. The immunochemical study of the preparation has demonstrated its serological specificity and high immunological activity, not inferior to that of serotyping antigenic preparations from group B meningococci, obtained by the heretofore known methods.     

Ways to prevent the calcification of heart valve bioprostheses

The influence of the method of preservation and application of medicinal preparation xydiphone on the process of calcification of xenograft bioprostheses in a classic model of subcutaneous implantation of bioprosthesis cusps in rats has been studied. It is estimated that fermentative processing does not influence the intensity of calcification, while the immobilization of heparin to tissue decreases the amount of calcium in implants 4.5 times. Combination of heparin immobilization with peroral administration of xydiphone results in summing up of the effects, decreasing the amount of calcium in experimental set of cusps up to the level of nonimplanted ones.     

Spontaneous variability in a population of Candida albicans strains]

The spontaneous variability of the populations of C. albicans strains of different genesis in the morphological properties of their colonies and in the potential of the activity of their extracellular proteolytic and phospholipid enzymes has been studied. The isolated types of colonies, differing in their morphology, have the phenotypic character of variability. Different populations of strains exhibited variability in the activity of enzymes, depending on morphological variants isolated from these populations. Selected morphological variants with high potential of their proteolytic enzymes retained stability in this property for 5 generations and can be used in medical practice for the isolation of C. albicans antigens.     

In Vivo Wound-Healing Activity of Glycerohydrogel Plates Based on Ascorbate Chitosan,Aloe vera,and Silicon Polyolate

Applied Biochemistry and Microbiology - An in vivo study of the healing properties of the glycerohydrogel plates based on L- and D-ascorbate chitosan, Aloe vera juice, and silicon tetraglycerolate...     

Behavior of plutonium in the body of rats following its intragastric administration in a complex with tributyl phosphate

A study was made of the distribution of plutonium-239 within the rat body after single intragastric administration thereof (1.85 MBq) in a mixture with tributyl phosphate (TBP) and as Pu(IV) nitrate at a time interval from 4 min to 512 days. It was shown that the distribution of the radionuclide was virtually the same but its absorption from the gastrointestinal tract with Pu-TBP was higher by one order of magnitude and exceeded the value recommended by ICRP for soluble plutonium compounds.     

The Ultramicrostructure of Tubiphyte Walls

An ultramicroscopic study of tubiphytes—tubular formations, composed of pelitomorphic calcite from the Lower Permian Tra-Tau reef (Cis-Urals)—was carried out. A multilayer structure of the walls was recognized. The inner layer is an ultrathin layer of acicular calcite crystals, which often has aragonite habit; the next layer is a relatively thick one represented by a dense pelitomorphic mass, which is often encrusted with the calcite crystals. Between the first and second layers are traces of mineralized biofilms, “lace” secretions of mineralized glycocalyx. It is assumed the inner layer is the tubiphyte wall and the pelitomorphic one is the result of biochemogenic carbonate precipitation as a consequence of ability of epiphytic bacterial activity, which colonized the walls of an original organism. A relatively high C/Ca ratio in the glycocalyx relics, its consequent decrease from the acicular wall towards the pelitomorphic one, and finally to the purely chemogenic crystalline formations of crustified rims is an indirect proof of such a formation mechanism of tubiphytes.