Molecular dynamics investigation of nitric oxide (II) interaction with a model biological membrane

Nitric oxide (II) diffusion through a model two-component (phosphatidylcholine and phosphatidylethanolamine molecules) biological membrane is investigated using the molecular dynamics method. It is shown that NO molecules are rotating in the process of diffusion into the phospholipid bilayer. The calculated diffusion coefficient D[NO] = 0.35 (±0.23) × 10^?5 (cm²/s) is in a good agreement with literature data. This testifies that free diffusion of NO molecules may be a plausible mechanism of the NO permeation through the membranes.     

Occurrence of oestrogenic pollutants and widespread feminisation of male tilapia in peri-urban dams in Bulawayo,Zimbabwe

Peri-urban water bodies are at risk from excessive pollution as they are direct sinks for urban effluents. The occurrence of oestrogenic and androgenic endocrine disrupting chemicals (EDCs) in effluents and water bodies around the city of Bulawayo, Zimbabwe, and their effects on wild fish was investigated in 2013. Effluent and water were sampled from sewage treatment plants, an urban stream, and effluent-polluted dams, and were compared with a ‘pristine’ dam upstream of Bulawayo. Organic pollutants were extracted by solid-phase extraction and tested for EDCs using a yeast oestrogen/androgen screen. Oestrogenic and androgenic potencies were expressed as 17β-oestradiol equivalent (EEq) or dihydrotestosterone equivalent (TEq). Tilapia and catfish from the dams were analysed for gonado-somatic indices and testis histopathology. Effluents from STPs, which directly flow into Umguza Dam, had EEq of 33 ng l^?1 and 55 ng l^?1, respectively. Umguza Dam, Khami Dam and Matsheumhlope Stream had EEqs of 237 ng l^–1, 9 ng l^?1 and 2 ng l^?1, respectively. Androgenic activity was detected in only one STP (TEq = 93 ng l^?1). Tilapia sampled from effluent-polluted dams had high incidences of testis-ova, but catfish had no signs of reproductive dysfunction. These findings underscore the need for greater attention to EDCs in developing countries where there is scant literature regarding their occurrence and impacts.     

Changes in the Antigenic Properties of Azospirillum brasilense Lipopolysaccharide,Induced by Addition of Tris-(hydroxymethyl)-aminomethane into the Culture Medium

Addition of tris-(hydroxymethyl)-aminomethane (Tris) into the culture medium of Azospirillum brasilense sp245 changes the antigenic properties of the lipopolysaccharide (LPS) isolated from the external membrane of the bacteria. LPS preparations from the bacteria grown in the presence of Tris have been analyzed by immunodiffusion, using monospecific antibodies. The disappearance of the precipitation band corresponding to one of the two O-specific polysaccharides of the LPS (O-PS) and changes in the electrophoretic profile have been revealed. However, only minor differences in absorption spectra of products of O-PS1 reaction with phenol/sulfuric acid have been demonstrated between the bacteria grown under standard conditions and in the presence of Tris.     

Structural-metabolic characteristics of acute hepatic failure]

Basing on early autopsy data, the study was made of structural and metabolic characteristics of the liver in marked intoxication and blood loss. Histologic, histoenzymatic and biochemical methods were used to evaluate morpho- and pathogenesis of acute liver failure arising in the above conditions.     

Atypical R–S Dissociation in Azospirillum brasilense

It was found that atypical R–S dissociation in the type strain A. brasilense Sp7 is not accompanied by drastic changes in the polysaccharide moieties of bacterial lipopolysaccharides but is rather due to different contributions of two O-specific polysaccharides (found in both R and S dissociants) to the age-dependent architectonics of the cell surface.     

Potentiation of NO-dependent activation of soluble guanylate cyclase by polyamines

The influence of polyamines (putrescine, spermidine, and spermine) on the activity of human platelet soluble guanylate cyclase and the stimulation of the enzyme by sodium nitroprusside (SNP), YC-1 and their combination was investigated. All these polyamines stimulated the guanylate cyclase activity and potentiated its activation by sodium nitroprusside. The stimulatory effects of sodium nitroprusside and putrescine (or spermine) were addidive; spermidine produced a synergistic activation and increased the additive effect. All the polyamines inhibited the enzyme activation by YC-1 and decreased the synergistic activation of SNP-stimulated guanylate cyclase activity by YC-1 with nearly the same potency. The ability of the investigated polyamines to potentiate and to increase synergistically (similar to to YC-1, but less effective) NO-dependent activation of soluble guanylate cyclase represents a new biochemical effect of these compounds; this effect should be taken into consideration, especially due to the endogenous nature of polyamines. The data obtained suggest, that specific biological functions of polyamines in the processes of growth and differentiation of cells may be also related to the ability of compounds to activate soluble guanylate cyclase and to increase intracellular cGMP level.