Thermal stability and functional properties of human hemoglobin in the presence of aliphatic alcohols]

Differential scanning microcalorimetry was used to study thermal stability of the ferro- and ferriforms of hemoglobin at pH 7.4 in phosphate buffer and in buffer mixtures of methanol, ethanol, 1-propanol. Denaturation of the human hemoglobin molecule composed of four subunits was cooperative transition. The thermostability of the hemoglobin forms decreased in the order of carboxyhemoglobin (TD = 82.0 degrees C) > oxyhemoglobin (71.0 degrees C) > methemoglobin (67.0 degrees C). The aliphatic alcohols as cosolvents decreased the hemoglobin stability because of loosening the structure of the globin moiety by disturbing its hydrophobic contacts and hydrogen bonds. These alcohols reduced the oxygen affinity for hemoglobin probably due to perturbation of the R<-->T equilibrium by the decreased bulk dielectric constant of the solvent. Oxyhemoglobin and methemoglobin was converted to hemichrome by high alcohol concentrations.     

Binding and biological properties of lipopolysaccharide Proteus vulgaris O25 (48/57)–chitosan complexes

In this study the negatively charged Proteus vulgaris O25 LPS was chosen for studying interaction with polycationic chitosan. The complex formation of LPS with chitosan was demonstrated using gradient centrifugation and laser interferometry method. The presented results have shown that laser interferometry method is sensitive enough for LPS–chitosan interaction studies. The changing in the ultra structure of LPS during binding with chitosan was observed by electronic microscope. The interaction of P. vulgaris O25 LPS with chitosan was shown to modulate significantly the biological activities of LPS. The toxicity of P. vulgaris O25 LPS decreased 10-fold after forming complexes with chitosan at injection to mice in the similar concentration of endotoxin. The complex LPS–chitosan was less effective than LPS alone in Limulus amabocyte lysate assay. Induction of TNF biosynthesis by LPS–chitosan complex was found to be 65% lower than that by parent LPS at concentration of 100 ng/ml.     

Glucose-regulated protein Grp78 affects characteristics of sleep and thermoregulation in rats

It was shown previously that sleep deprivation in representatives of warm-blooded animals evokes an elevation of the glucose-regulated protein 78 (Grp78) gene expression in the brain structures involved in the control of sleep and thermoregulation. However it is currently unknown what role the increased Grp78 expression plays in the mechanisms that maintain homeostasis of sleep and thermoregulation. Using electrophysiological methods, it has been shown in this study that microinjections of Grp78 into the third brain ventricle of Wistar rats evokes an increase mostly in deep non-rapid-eye-movement (NREM) sleep (due to a lengthening of the NREM sleep episodes) and a decrease in the amount of rapid-eye-movement sleep. The period of deep NREM sleep was accompanied by a reduced muscle contractile activity. Our results provide evidence that Grp78 is implicated in the molecular mechanisms of maintenance of deep NREM sleep typically accompanied by a decrease in muscle contractile activity.     

Study of protective effects of exogenous heat shock protein 70 kDa in model of sleep deprivation in pigeon <Emphasis Type="Italic">Columba livia</Emphasis>

Electroencephalographic methods were used to study effects of preparation of the exogenous heat shock protein with molecular mass of 70 kDa (Hsp70i/Hsc70) on time characteristics of sleep and wakefulness, brain temperature, peripheral vasomotor reactions, and thoracic muscle contractile activity after the 5-hour forceful sleep deprivation in the pigeon Columba livia. Administration of Hsp70i/Hsc70 into the third brain ventricle at once after the end of sleep deprivation eliminated disturbances in the sleep-wakefulness cycle organization and decreased the thoracic muscle contractile activity and the brain temperature as early as for the first hour of postdeprivation period. For the subsequent hours, the Hsp70i/Hsc70 action was characterized by an increase of the total time of deep sleep and a decrease of the total time of the rapid eye movement sleep. We suggest that the protective effects of the exogenous Hsp70i/Hsc70 preparation are associated with its ability to decrease activity of the hypothalamo-pituitary-adrenal axis and to enhance the stress-limiting function of the slow eye movement sleep.     

A study of the antiviral activity of cyclopentene β,β′-triketone disodium salt in the leaves of two <Emphasis Type="Italic">Nicotiana tabacum</Emphasis> L. cultivars infected with tobacco mosaic virus

The effect of disodium salt of 2-acetyl-4-hydroxycarbonylmethylthio-5-chlorocyclopent-4-en-1,3-dione on development of the infection caused by tobacco mosaic virus in the leaves of two Nicotiana tabacum L. cultivars—an hypersensitive cultivar Xanthi-nc and systemically affected Samsun—was studied. The results suggest that this compound interferes with reproduction of the virus. This antiviral effect displayed the highest activity when applied in a mixture with the virus, presumably due to its action on both the plant and the virus.     

Effect of 1,3;1,6-β-D-glucan on Infection of Detached Tobacco Leaves with Tobacco Mosaic Virus

Glucan preparations were obtained by transformation of laminaran from the alga Laminaria cichorioides with endo-β-1,3-glucanase from marine mollusks. These preparations, like those of other sources, have an inhibitory effect on tobacco mosaic virus (TMV) infection of detached leaves of local and systemic host tobacco plants.     

Diabetes mellitus: Metabolic effects and oxidative stress

Diabetes mellitus is a complex polygenic pathology, which is characterized by numerous metabolic disorders. Progressive hyperglycemia developing during this disease causes clinically significant tissue damage and is considered as a main risk factor of micro- and macrovascular complications leading to retinopathy, nephropathy, and neuropathy. Hyperglycemia-depended oxidative stress and impairments in nitric oxide bioavailability play an essential role in the pathogenesis of diabetes and its complications. Homeostasis of glucose maintained by metabolic effects of insulin includes an increase of glucose uptake by skeletal muscles and suppression of glucose production by the liver. M. Brownlee (2005) put forward a hypothesis assuming that oxidative stress is the main mechanism of diabetic tissue damages. According to this hypothesis, mitochondrial dysfunction and superoxide anion radical hyperproduction by mitochondria is the principal mechanism of activation of four pathways of hyperglycemia-induced impairments under diabetes. Two cell signaling cascades regulate the glucose homeostasis: insulin-mediated glucose uptake (IMGU) in skeletal muscles, liver, and heart and glucose-stimulated insulin secretion (GSIS) in pancreatic β-cells. In addition to nonspecific irreversible oxidative damage of DNA, protein and lipid molecules reactive oxygen and nitrogen species induce cell and tissue damage, activating a number of cell stress-sensitive signaling cascades. Stress-dependent serine phosphorylation of insulin receptor substrate (IRS) proteins decreases its capacity for tyrosine phosphorylation and may accelerate degradation of IRS. This process underlies the molecular mechanism of oxidative stress-induced insulin resistance.     

Cranberry flavonoids prevent toxic rat liver mitochondrial damage in vivo and scavenge free radicals in vitro

The present study was undertaken for further elucidation of the mechanisms of flavonoid biological activity, focusing on the antioxidative and protective effects of cranberry flavonoids in free radical‐generating systems and those on mitochondrial ultrastructure during carbon tetrachloride‐induced rat intoxication. Treatment of rats with cranberry flavonoids (7 mg/kg) during chronic carbon tetrachloride‐induced intoxication led to prevention of mitochondrial damage, including fragmentation, rupture and local loss of the outer mitochondrial membrane. In radical‐generating systems, cranberry flavonoids effectively scavenged nitric oxide (IC₅₀ = 4.4 ± 0.4 µg/ml), superoxide anion radicals (IC₅₀ = 2.8 ± 0.3 µg/ml) and hydroxyl radicals (IC₅₀ = 53 ± 4 µg/ml). The IC₅₀ for reduction of 1,1‐diphenyl‐2‐picrylhydrazyl radicals (DPPH) was 2.2 ± 0.3 µg/ml. Flavonoids prevented to some extent lipid peroxidation in liposomal membranes and glutathione oxidation in erythrocytes treated with UV irradiation or organic hydroperoxides as well as decreased the rigidity of the outer leaflet of the liposomal membranes. The hepatoprotective potential of cranberry flavonoids could be due to specific prevention of rat liver mitochondrial damage. The mitochondria‐addressed effects of flavonoids might be related both to radical‐scavenging properties and modulation of various mitochondrial events. Copyright © 2015 John Wiley & Sons, Ltd.