Behavioral and electrophysiologic characteristics of a peptide analog of piracetam--L-pyroglutamyl-D-alanine amide

The effect of L-pyroglutamyl-L-alanine amide, a structural analog of nootropil, was studied in the passive and active conditioned avoidance tests in rats. The compound (1 mg/kg, i. p.) was shown to be able to improve the performance in the shuttle-box. This effect is selective because it is not followed by psychomotor stimulation. In experiments on undertrained animals in passive avoidance test the compound reveals its positive amnestic effect with its administration prior to, immediately after learning and prior to testing. This provides the evidence that the dipeptide activates all the phases of memory formation. The compound raises the amplitude of transcallosal responses in temporal associative area and S-1 and increases facilitation phase in the recovery cycle, being inactive in respect to primary somatosensory evoked responses in S-1. All the data obtained suggest the nootropil-like effect of the dipeptide. The analysis of the dipeptide by MR-spectrometry reveals its stability in the presence of serum or enterocyte enzymes.     

Interaction of an analog of the E1 site of tetrapeptide Gly-Pro-Arg-Pro with the D1 site of two forms of monomeric fibrin

Two monomeric fibrin forms differing in a set of polymerization sites (fibrin desAA and fibrin-desAABB) are inhibited to a different extent by tetrapeptide Gly-Pro-Arg-Pro which simulates a moiety of polymerization site E1. The lesser sensitivity of fibrin-desAABB polymerization to the inhibiting tetrapeptide is due to the presence of active site E2 in it. A shape of the concentration dependence curve of the inhibitory effect of tetrapeptide Gly-Pro-Arg-Pro on the polymerization of both fibrin types is similar to the previously found curve for fibrinogen and its fragments--specific inhibitors of polymerization. Ca2+ intensifies inhibition of fibrin-desAABB polymerization by tetrapeptide Gly-Pro-Arg-Pro twice as much as that of fibrin-desAA evidently due to the peptide blockage of sites D2. An increase of the ionic strength from 0.15 to 0.3 enhances the inhibitory effect of the tetrapeptide on polymerization of two monomeric fibrin forms.     

Status of Acute Symptomatic Seizures in a Female Patient with Thyrotoxicosis: Hashimoto’s Encephalopathy. A Case Report

Hashimoto’s encephalopathy is an autoimmune disease associated with a significant increase in the titer of autoantibodies to thyroid peroxidase and thyroglobulin and is characterized by inflammatory and degenerative brain disorders. We report a clinical case of the recurrent status of acute symptomatic seizures in a female patient with Hashimoto’s encephalopathy.     

Antimicrobial immunity in patients with acute epiglottitis

Fifty-three patients with catarrhal epiglottitis and 31 patients with epiglottic abscess aged 16-60 years were examined. It was determined that development of epiglottitis is tightly related to abnormalities in reactivity of phagocytic and humoral arms of immunity. Decreased affinity of produced antibodies, opsonizing properties of serum as well as phagocytic and biocide activity of neutrophils were revealed in patients. In patients with catarrhal and necrotic epiglottitis similar abnormalities of immunoreactivity were observed although in patientswith necrotic epiglottitis they were more pronounced.     

Legionella natural biofilms and their role in epidemiology of the infection: methods of study and modelling

Ability of Legionella species to form biofilms in association with other microorganisms is the key factor of their spreading in potentially dangerous water systems. Ability of different strains of Legionella to form monospecies biofilms as well as biofilms in association with Pseudomonas aeruginosa in constant conditions was analyzed. It was shown that ability of Legionella strains to form monospecies biofilms correlates with their ability to persist in biofilms formed by P. aeruginosa.     

Nitric oxide-induced membrane tubulovesicular extensions (cytonemes) of human neutrophils catch and hold Salmonella enterica serovar Typhimurium at a distance from the cell surface

Nitric oxide (NO) plays an important role in host defense against bacterial infections such as salmonellosis. NO and 4-bromophenacyl bromide (BPB) induce the formation of long tubulovesicular extensions (TVE, cytonemes, membrane tethers) from human neutrophils. These TVE serve as cellular sensory and adhesive organelles. In the present study, we demonstrated that in the presence of the NO donor, diethylamine NONOate or BPB human neutrophils bound and aggregated Salmonella enterica serovar Typhimurium bacteria extracellularly by TVE. In contrast, inhibition of NO-synthase activity by N ^ω-nitro- l -arginine methyl ester stimulated neutrophil phagocytosis (ingestion) of bacteria. Neutrophil TVE consisted of membrane-covered cytoplasm as was shown by the fluorescent cytoplasmic dye 2',7'-bis(2carboxyethyl)-5,(6)-carboxyfluorescein, and the fluorescent lipid, BODIPY-labeled sulfatide. Disruption and shedding of TVE were accompanied by the appearance of specific invaginations (porosomes) on neutrophil cell bodies. These invaginations corresponded to the variations in diameter of TVE (160–240 nm). We hypothesized that TVE represented protrusions of neutrophil exocytotic trafficking through special structures on the neutrophil surface. In conclusion, we propose a novel mechanism by which NO-induced TVE formation enables neutrophils to bind and aggregate bacteria at a distance.     

Rice resistance to blast caused by leaf surface moistening prior to inoculation

Effect of water droplets placed onto rice (Oryza sativa L.) leaves before inoculation with blast fungus Magnaporthe grisea (Hebert) Barr on disease severity and superoxide radical generation by the leaves was investigated. The leaves were inoculated by placement of spore suspension droplets. One day before, droplets of distilled water were placed to the same sites as an inoculum. It was found, that such a pretreatment decreased frequency of susceptible-type lesions by 2 to 2.5 times and increased that of symptomless outcome by 1.5 times in comparison with the nontreated control. Besides, the pretreatment enhanced superoxide radical generation in diffusates of healthy leaves of susceptible cultivar and in diffusates of infected leaves of resistant cultivar one day post inoculation. It is suggested that water contacting with the leaf surface for a rather long time washes out from its cells compounds possessing properties of plant endogenous elicitors. The latter induce superoxide radical formation by plants and, as a consequence, their disease resistance. This may be interpreted as plant adaptation to high humidity, which usually favors infections.     

Exit of GPI‐Anchored Proteins from the ER Differs in Yeast and Mammalian Cells

Previous studies have shown that yeast glycosylphosphatidylinositol‐anchored proteins (GPI‐APs) and other secretory proteins are preferentially incorporated into distinct coat protein II (COPII) vesicle populations for their transport from the endoplasmic reticulum (ER) to the Golgi apparatus, and that incorporation of yeast GPI‐APs into COPII vesicles requires specific lipid interactions. We compared the ER exit mechanism and segregation of GPI‐APs from other secretory proteins in mammalian and yeast cells. We find that, unlike yeast, ER‐to‐Golgi transport of GPI‐APs in mammalian cells does not depend on sphingolipid synthesis. Whereas ER exit of GPI‐APs is tightly dependent on Sar1 in mammalian cells, it is much less so in yeast. Furthermore, in mammalian cells, GPI‐APs and other secretory proteins are not segregated upon COPII vesicle formation, in contrast to the remarkable segregation seen in yeast. These findings suggest that GPI‐APs use different mechanisms to concentrate in COPII vesicles in the two organisms, and the difference might explain their propensity to segregate from other secretory proteins upon ER exit.