Results 1 - 10 of 1932
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[en] A sensitive double-antibody radioimmunoassay for staphylococcal enterotoxins A and B is described. The separation of the primary antigen-antibody complex of enterotoxin A and B was achieved with an anti-rabbit gamma globulin from goats. Radioiodinated aggregate fractions of staphylococcal enterotoxins exhibited reduced immunological activity and showed little competition with non-radioactive enterotoxin. The radioimmunoassay was successfully applied for the quantitation of enterotoxins in food. (author)
[en] Highlights: • Closed- and open-state models of hNav1.4 are shown. • The incomplete outward movement of S4 of domain III holds the channel closed. • The presence of intermediate state in S4 outward movement is revealed. • Movement of ∼6.5 elementary charges is required to activate the channel from hyperpolarized state. • Beta-scorpion toxin Ts1 binds to the closed-state model. Voltage-gated sodium channels play important roles in human physiology. However, their complexity hinders the understanding of their physiology and pathology at atomic level. We took advantage of the structural reports of similar channels obtained by cryo-EM (EeNav1.4, and NavPaS), and constructed models of human Nav1.4 channels at closed and open states. The open-state model is very similar to the recently published cryo-EM structure of hNav1.4. The comparison of both models shows shifts of the voltage sensors (VS) of DIII and DIV. The activated position of VS-DII in the closed model was demonstrated by Ts1 docking, thereby confirming the requirement that VS-DI, VS-DII and VS-DIII must be activated for the channel to open. The interactions observed with VS-DIII suggest a stepwise, yet fast, transition from resting to activated state. These models provide structural insights on the closed-open transition of the channel.
[en] Highlights: • Ocular P. aeruginosa isolates induce autophagy in human corneal epithelial cells. • T3SS mutants were defective in inducing autophagy and becn1 expression. • T3SS (−)ve strains were less sensitive to external autophagy modulators. • Pro-autophagic role of T3SS regulates intracellular survival of P. aeruginosa. Corneal ulcers caused by Pseudomonas aeruginosa may lead to severe visual disability due to impaired bacterial clearance from corneal tissues. Our purpose was to study the role of autophagy in the intracellular clearance of P. aeruginosa from human corneal epithelial cells (HCET) and its regulation by the bacterial type III secretion system (T3SS) toxins. Nine different corneal ulcer isolates of P. aeruginosa, PAO1 and T3SS mutants of PAO1 were used to infect HCET cells. Induction of autophagy (Immunofluorescence and Western blot) and pro-inflammatory gene expression (real time PCR) by P. aeruginosa and the role of autophagy in intracellular bacterial clearance were studied in the context of T3SS genotypes. The clinical isolates and PAO1 induced autophagy irrespective of the T3SS genotype, whereas the T3SS mutants were relatively defective in inducing autophagy and becn1 gene expression. External induction of autophagy significantly reduced the intracellular load of P. aeruginosa strains that were associated with worst clinical outcomes. The T3SS negative isolate and PAO1ΔexoST were less sensitive to pharmacological modulation of autophagy and had relatively higher replication potential, suggesting a possible mechanism of bacterial survival in the absence of T3SS toxins. Overall, our results highlight a selective role for autophagy in bacterial clearance from corneal epithelial cells and emphasize the pro-autophagic role of bacterial toxins in the context of corneal ulcers.
[en] In order to establish optimum conditions of radiosterilization, dry vaccines from anatoxics and typhoid antigen were irradiated on irradiation units of types EPGU-200 and LUE-25/8 using doses of 1.25, 2.5, and 10 Mrads. It was found that the dose of 2.5 Mrads assured complete sterility of the preparations including those contaminated with spores, without altering their biological properties. (author)
[en] The method is applicable to the determination of ochratoxin A in malting barley, malt and cereals in general; it can serve as an expeditious screening method. The principles, instrumentation and chemicals as well as the working procedure are described. The detection limit is 1.2 μg/kg, recovery (at 20 μg/kg) is 0.67 ± 0.08. (Z.S.). 1 ref
[en] The authors' findings indicate that irradiation confers no advantage over heat processing in respect of bacterial toxins (clostridium botulinum, neurotoxin A and staphylococcal enterotoxin A). It follows that irradiation at doses less than the ACINF recommended upper limit of 10 kGy could not be used to improve the ambient temperature shelf life on non-acid foods. (author)
[en] Full text: Introduction - Lead (Pb) is a soil pollutant that has no known essential biological function. Nonetheless it poses a threat to soil-dwelling organisms and human health. Anthropogenic sources of Pb, such as old paints, mining and smelting, have caused Pb contamination of soil in residential areas (Laidlaw and Taylor, 2010;Oyarzun, Lillo et al., 2011). It is well established that the total Pb concentration in soil does not accurately represent its bioavailability (Drexler and Brattin, 2007;Lamb, Ming et al., 2009) and a wide range of chemical and biological techniques are being used to assess the bioavailable fraction in soils (Naidu, Rogers et al., 2003; Naidu, Semple et al., 2008). Considerable change in metal bioavailability occurs due to a time-dependent process called “ageing” (Naidu, Rogers et al., 2003; Vig, Megharaj et al., 2003). Ageing causes metal bioavailability to decrease with time. Monitored natural attenuation (MNA) of contaminated soils has served as an attractive remediation option for decades. In addition to natural attenuation processes, one assumption in MNA is that contaminant bioavailability in soils decrease with time (i.e. with ageing) (Naidu, Megharaj et al., 2000). The current study investigated the extent and intensity of the changes in Pb bioavailability in four contrasting soils over a time period (56 days) until the Pb relative bioavailability (RB) levels achieved a steady state. This helped to assess the extent of: firstly, bioavailability change in each soil; and secondly, correlation of these changes with the soil properties. Methods - Four soils used in this study were collected from uncontaminated sites in Queensland and South Australia. Relative bioavailability of soils spiked with 1500 mg Pb/kg were measured in swine that were fed these soils, throughout an ageing period (56 days) to investigate relationships between soil properties and in vivo bioavailability of Pb. Spiked soils were used to minimize the effect of varying sources of Pb on RB. Metal sorption studies were conducted by equilibrating 1-g samples of soil in separate tubes with varying concentrations of Pb acetate in 30 ml 0.03 mol/L NaNO3, in duplicate. In this study Kd was obtained from the Freundlich adsorption equation. In total 78 Landrace-large white female swine weighing 20-25 kg were used for the bioavailability assays. The pigs were given a dose (oral or IV) of Pb either as a solution of soluble Pb salt [Pb acetate = (CH3COO)2Pb.3H2O] or soil contaminated with the same source of Pb. Blood samples were collected at 0, 1, 2, 3, 4, 5, 6, 7, 8, 10, 24, 48, 96 and 120 h following dose administration. These samples were then immediately diluted 20-fold in diluent solution containing 1- butanol (2% w/v), EDTA (0.05% w/v), Triton X-100 (0.05% w/v) and ammonium hydroxide (1% w/v) in Milli-Q water, and stored at 2-8 °C prior to Pb analysis. Bioavailability was derived from the areas under the blood Pb concentration – time curves (AUC) described by a two-compartment pharmacokinetic model (Zhang, Huo et al., 2010) for results from Pb administered as IV (intravenous) dose, oral solution or as spiked soils. Results and discussion - The bioavailability of Pb in soils in the freshly spiked soils highlighted a significant inverse correlation with pH (r=-0.909, p<0.05) and EC (R=-0.918, P<0.05) which indicated that an increase in pH or EC led to a significant decrease in RB. Many researchers have shown increased metal sorption occurring with increasing pH due to an increase in surface negative charge of the constant potential soil constitutes leading to increased sorption and as a consequence low Pb or metal bioavailability (Cao, Ma et al., 2011;Naidu, Bolan et al., 1994). In contrast to freshly spiked soil where Pb RB showed a significant correlation with pH and EC, the steady state RB of soils significantly (p<0.05) correlated with clay content (r=-0.95) and CEC (r=-0.91), The RB of Pb in GTA, IWA and MLA decreased from their initial Pb RB values until a steady state RB of 34%, 45% and 59% was reached respectively by the 56th day. In contrast, however, to these RB decreases, NTA soil indicated no change in RB over the whole ageing period of the experiment. The lack of change in RB in the NTA soil over time was attributed to it achieving a steady state RB within a very short time due to its comparatively high sorptive capacity (kd=112). (author)
[en] Highlights: • TRPV4 is upregulated in glioma, and high-level of TRPV4 indicates a worse prognosis. • TRPV4 activation enhances the cell migration and invasion of glioma. • TRPV4-induced cell motility via AKT/Rac1 signaling pathway. Experimental evidence indicates a critical role of TRPV4 (Transient Receptor Potential Vanilloid 4) in controlling the cell migratory activity of multiple tumors. However, the oncogenic role of TRPV4 in glioma still remains elusive. In this study, we tried to investigate the oncogenic role of TRPV4 in glioma. We found that the expression levels of TRPV4 were upregulated in glioma and the high levels of TRPV4 indicated a worse prognosis in patients with glioma. TRPV4 was critical for glioma migration and invasion: activating TRPV4 by agonist GSK1016790 A enhanced glioma migration and invasion, while, the specific TRPV4 antagonist HC-067047 suppressed glioma migration and invasion. Mechanically, activated TRPV4 promoted the activation of Rac1 (Ras-related C3 botulinum toxin substrate 1) by targeting the AKT for phosphorylation, then enhanced glioma migration and invasion. All these results suggested that TRPV4 accelerates glioma migration and invasion through the AKT/Rac1 signaling, and TRPV4 might be considered as a potential target for glioma therapy.