Relation between the passive transport of calcium into vesicles of the myocardial sarcolemma and membrane potential

The effect of membrane potential on the passive 45Ca2+ uptake by cardial sarcolemmal vesicles was investigated. Membrane potentials were generated by the K+ gradient in the presence of valinomycin and were measured using fluorescent dye diS-C3-(5). It was shown that the 45Ca2+ influx into vesicles increased twice after membrane depolarization. Evaluation of the 45Ca2+ influx over a wide range of membrane potentials produced a profile similar to that of current-voltage relationships for single calcium channels in isolated cardiomyocytes. Passive 45Ca2+ transport was inhibited by 1 mM Cd2+ and Co2+. It is suggested that the voltage-dependent Ca2+ influx into vesicles occurs through Ca2+-channels.     

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.     

Extramedullary hematopoiesis in a case of benign mixed mammary tumor in a female dog: cytological and histopathological assessment

Backgroud  

Extramedullary hematopoiesis (EMH) is defined as the presence of hematopoietic stem cells such as erythroid and myeloid lineage plus megakaryocytes in extramedullary sites like liver, spleen and lymph nodes and is usually associated with either bone marrow or hematological disorders. Mammary EMH is a rare condition either in human and veterinary medicine and can be associated with benign mixed mammary tumors, similarly to that described in this case.     

Physicochemical properties of chitin-melanin and melanoprotein complexes from bee corpses

A technology for processing bee corpses and obtaining chitin-melanin and melanoprotein complexes has been developed. The obtained complexes of biopolymers were studied by the methods of absorption spectroscopy, electron paramagnetic resonance (EPR) spectroscopy, thermogravimetry, and differential scanning calorimetry. The elemental composition of preparations was characterized. It was shown that the properties of the melanin-containing products of the processing of bee corpses are typical of chitin and melanin of animal origin. The results of EPR spectroscopy and thermal analysis are indicative of the diversity and structural complexity of the obtained products.     

Flavonoids as effective protectors of urease from ultrasonic inactivation in solutions

Inactivation of soybean urease in aqueous solution at pH 5.4, 36°C, and high-frequency sonication (2.64 MHz, 1.0 W/cm²) is substantially reduced in the presence of seven structurally different flavonoids. A comparative kinetic study of the effect of these flavonoids on the effective first-order rate constants that characterize the total (thermal and ultrasonic) inactivation k _i , thermal inactivation k*_i, and ultrasonic inactivation k _i (US) of 25 nM enzyme solution was carried out. The dependences of the three inactivation rate constants of the urease on the concentrations of flavonoids within the range from 10^?11 to 10^?4 M were obtained. The following order of the efficiency of the flavonoids used in respect of the urease protection from ultrasonic inactivation was found: astragalin > silybin > naringin > hesperidin > quercetin > kaempferol > morin. The results confirm a significant role in the inactivation of the urease of HO^. and HO ₂ ^. free radicals, which are formed in the ultrasonic cavitation field.     

Molecular taxonomic identification of Schistosomatidae from Naroch Lake and Polonevichi Lake in Belarus

In Belarus, Naroch Lake is the only area with a high incidence of the human cercarial dermatitis (HCD). However, very little is known about the taxonomy of avian schistosomes, the causative agents of the disease, which are found in Naroch Lake and other lakes in Belarus. In this study, we used a molecular approach to investigate the systematic position and biodiversity of avian schistosomes from Naroch Lake and Polonevichi Lake. Based on the sequence analysis of the ITS genomic region, we were able to detect four different species of bird schistosomes in Naroch Lake (Trichobilharzia szidati, Trichobilharzia franki, Bilharziella polonica and a novel Trichobilharzia species) and two species in Polonevichi Lake (T. szidati and B. polonica). The data were used to reveal the phylogenetic position of HCD causative cercariae found in Belarusian water reservoirs and to establish their relationships within the group of avian schistosomes. We discuss the possibility of identifying species of Trichobilharzia using the fragment length polymorphism analysis of the ITS region. Possible epidemiological causes of HCD incidence in Belarus are also discussed.     

Physicochemical properties of chitin-melanin and melanoprotein complexes from bee corpses

A technology for processing bee corpses and obtaining chitin-melanin and melanoprotein complexes has been developed. The obtained complexes of biopolymers were studied by the methods of absorption spectroscopy, electron paramagnetic resonance (EPR) spectroscopy, thermogravimetry, and differential scanning calorimetry. The elemental composition of preparations was characterized. It was shown that the properties of the melanin-containing products of the processing of bee corpses are typical of chitin and melanin of animal origin. The results of EPR spectroscopy and thermal analysis are indicative of the diversity and structural complexity of the obtained products.     

Flavonoids: Efficient protectors of glucose-6-phosphate dehydrogenase from ultrasonic cavitation-induced inactivation

Seven structurally diverse flavonoids have been shown to decrease glucose-6-phosphate dehydrogenase (G6PDH) inactivation in 0.1 M phosphate buffer (pH 7.4), induced by exposure to a high temperature (44°C), or by a low-frequency ultrasound (27 kHz, 60 Wt/cm²). The activity of the compounds was assessed by their ability to change effective first-order rate constants characterizing the total (thermal and ultrasonic), thermal, and ultrasonic inactivation of 2.5 nM G6PDH (k _in, k*_in, and k _in(us), respectively). The value dependences of these constants on flavonoid concentrations (0.01–50 μM) were obtained. Rank order of potency exhibited by the compounds in protecting G6PDH appeared as follows: hesperidin > morin > silibin > naringin = quercetin > kampferol ? astragalin. The data obtained confirm the crucial role of free radicals formed in the field of ultrasonic cavitation (HO^· and O ₂ ^·? in G6PDH inactivation in solutions.     

Antioxidant properties of fungal melanin pigments

Fungal melanin pigments were shown to display a high antioxidant activity. An increase in the number of methyl substituents in benzidine molecules of melanins obtained from micromycetes and macromycetes was accompanied by a decrease in the efficiency of inhibition of peroxidase-mediated oxidation. Melanins were found to have considerable gene-protecting properties. Pigments isolated from macromycetes and applied at a much lower concentration than those obtained from micromycetes prevented damage to bacteriophage-λ DNA induced by products of peroxidase-mediated degradation of aminobiphenyls.     

Antioxidant activity of oxygen-containing aromatic compounds

Inhibition efficiency (antioxidant activity) of 26 oxygen-containing aromatic compounds was studied in methemalbumin-H₂O₂-o-phenylenediamine (PDA) or tetramethylbenzidine (TMB) pseudoperoxidase system at 20°C in buffered physiological solution (pH 7.4) containing 6% DMF and 0.25% DMSO. The inhibitor’s efficiency was quantitatively characterized by the inhibition constants (K _i, μM) or the inhibition degree (%). K _i values varied in the range of 4 to 500 μM and were influenced by a substrate, the structure of an inhibitor, hydroxyl groups, electron-donating substituents in aromatic ring, and steric hindrances. The type of inhibition at cooxidation of eight pairs was noncompetitive, and that of five pairs was mixed and determined by the substrate nature and the inhibitor structure. Lignin phenolic compounds of guaiacyl and syringal series exhibited high antioxidant activity (K _i in the range of 10–300 μM), and their efficiency decreased in the following order: caffeic acid > synapaldehyde > syringic acid > coniferyl aldehyde > para-hydroxycoumaric acid.