Adsorption of sterigmatocystin by montmorillonite and inhibition of its genotoxicity in the Nile tilapia fish (Oreachromis nilaticus)

Sterigmatocystin (Stg) is closely related to the mycotoxin aflatoxin as a precursor in aflatoxin biosynthesis and classified as an IARC Group-2B carcinogen. The aim of this study was to investigate the efficacy of Egyptian montmorillonite (EM), a clay mineral, to adsorb Stg, to test the stability of the resulting complex under different conditions in vitro, and to utilize the Nile tilapia fish as an in vivo model to evaluate the protective effect of EM against Stg-induced toxicity and clastogenicity. In the in vitro study, four concentrations of EM (0.5, 1, 2 and 4 mg/L aqueous solution) and three concentrations of Stg (5, 10 and 50 microg/ml) were tested. The results show that EM had a high capacity of adsorbing Stg at different concentrations tested. The adsorption ranged from 93.1 to 97.8% of the available Stg in aqueous solutions. The complex was stable at different pHs at 37 degrees C in different organic solvents. An in vivo experiment was conducted to evaluate the ability of EM to prevent the toxicity and chromosomal aberrations induced by Stg in the Nile tilapia fish. Fish received an intragastric dose of EM in corn oil (0.5 mg/kg bw) with or without Stg (1.6 microg/kg bw) twice a week for 4 weeks. Body weight was recorded during dosing, and blood and tissue samples were collected at the end of treatment. Stg residues were determined in fish tissue. The results show that Stg was toxic and clastogenic to fish as indicated by the significant decrease of body weight and the increase in frequencies of micronucleated red blood cells (MN RBC) and chromosomal aberrations in the kidney. The intragastric administration of EM combined with Stg to fish resulted in a reduction of the number of MN RBC and the frequency of chromosomal aberrations in the kidney compared with the group treated with Stg alone. It could be concluded that EM itself was safe and successful in the prevention of Stg toxicity and clastogenicity.     

Heavy metals resistant plasmid-mediated utilization of solar by Pseudomonas aeruginosa AA301

Solar-degrading bacteria, Pseudomonas aeruginosa strains, were isolated from Egyptian soil by Mineral Salt Medium (MSM) supplemented with Solar (motor fuel) from different oil-contaminated sites in Sohag province. The strain AA301 of Pseudomonas aeruginosa showed appreciable growth in MSM medium containing high concentrations of Solar ranging from 0.5 to 3% (v/v), with optimum concentration at 1.5%. Solar was used as a sole carbon source and a source of energy by the bacterium. The ability to degrade Solar was found to be associated with a single 60-kb plasmid designated pSOL15. The plasmid-cured variant, which was obtained by culturing in LB broth with kanamycin, lost the plasmid indicative the ability to degrade Solar must depend on this plasmid. The wild type isolate, Pseudomonas aeruginosa AA301 and transformant strain, have maximum growth (OD600 = approximately 2) on Solar, however the plasmid-cured variant did not have any significant growth on Solar. Moreover, resistance to a wide range of heavy metals such as Mn2+, Hg2+, Mg2+, Cd2+, Zn2+, and Ni2+ was also 60-kb plasmid-mediated. Therefore, the strain AA301 could be good candidate for remediation of some heavy metals and oil hydrocarbons in heavily polluted sites.     

SDS-PAGE heat-shock protein profiles of environmental Aeromonas strains

Aeromonas microorganisms normally grow at temperatures between 5 degrees C and 45 degrees C and therefore should have high thermotolerance. Thus it was of interest to find out whether A. hydrophila, A. caviae and A. veronii biovar sobria serovars respond to abrupt temperature changes with a heat shock-like response. To this end the present study was undertaken to determine whether Aeromonas species exhibits a heat shock response to different temperatures and time factors. The response of Aeromonas serovars to 24 h and 48 h of thermal stress at 25 degrees C, 42 degrees C and 50 degrees C involved the synthesis of 12-18 heat shock proteins (HSPs) bands with molecular weights ranging between 83.5-103.9 kDa in the high HSP molecular mass and 14.5-12.0 as low molecular mass HSP. Electrophoretic analysis of the HSPs showed that the serovars do not cluster very tightly and also that they are distinct from each other.     

Amplified immunohistochemical detection of PrPsc in animal transmissible spongiform encephalopathies using streptomycin.

Due to its sensitivity, immunohistochemistry (IHC) of abnormal prion protein (PrPsc) is used to study experimental and natural cases of transmissible spongiform encephalopathies (TSEs) such as Creutzfeldt-Jakob disease in humans or scrapie and bovine spongiform encephalopathy (BSE) in animals. The limits of detection are particularly critical when PrPsc IHC is used for diagnostic purposes. In this article, we describe for the first time the use of streptomycin sulfate in IHC, providing a novel original and easy way to amplify specifically PrPsc immunohistochemical detection in natural cases of BSE and scrapie, as well as in experimental TSEs in mice models using two different PrP antibodies.     

The effect of chronic cadmium exposure on the pharmacokinetics of theophylline and ciprofloxacin in rats

Cadmium has been associated with a number of adverse health effects but the impact of those effects on the pharmacokinetics of different drugs has not been investigated. Therefore, the pharmacokinetics of theophylline and ciprofloxacin were studied in cadmium-exposed and control rats (72 rats) following i.p. (6.5mg/kg) and p.o. (10mg/kg) administration, respectively. The third-generation offsprings of rats exposed to 100 microg/mL of cadmium chloride in drinking water were used in this study. Following 8 weeks of exposure, animals received the drugs as a single dose. Blood samples were withdrawn at different time-points and the plasma concentrations of both drugs were analyzed by HPLC. The pharmacokinetic parameters of theophylline and ciprofloxacin were altered significantly in the cadmium-exposed animals. For theophylline, a statistically significant increase (p<0.0001) in C(max) (69%) and AUC(0-)(infinity) (68%) of theophylline in the cadmium-exposed rats as compared to the control were observed. A corresponding significant (p<0.0001) reduction of 41% in clearance (CL/F) of theophylline was detected in the exposed group. Neither the half-life nor the mean residence time (MRT) showed any significant change due to the exposure to cadmium. For ciprofloxacin, no significant difference was seen in the C(max) of the exposed group as compared to the control animals. However, a delay in T(max) was observed in the exposed group (from 0.16(+/-0.003) to 0.37(+/-0.14)h). A small, but significant increase in t(1/2) (p<0.05) was detected (1.74(+/-0.25) vs. 1.45(+/-0.12)h). A significant reduction (p<0.05) of CL/F from 30.54(+/-1.9) to 24.01(+/-3.81)mL/min/kg was seen in the treated group. The current investigation showed that chronic exposure to cadmium could have a very significant impact on altering the pharmacokinetic parameters of various drugs. Therefore, in cadmium-polluted areas, dose adjustments and drug monitoring, especially for drugs with a narrow therapeutic window, should be carried out.     

Identifying people at high risk for developing sleep apnea syndrome (SAS): a cross-sectional study in a Pakistani population

Background  

Obstructive Sleep Apnea (OSA) is associated with many cardiovascular and psychiatric diseases. Day-time sleepiness is a common consequence of sleep apnea and correlates with road-traffic accidents (RTA). Pakistan has a high prevalence of factors which predispose an individual to OSA and death from RTAs are a huge burden. However there is a dearth of prevalence studies in this regard. We aim to understand local relevance of the disease and estimate the prevalence of individuals high-risk for OSA.     

The phytoseiid mitePhytoseius plumifer as a predator of the eriophyid miteAceria ficus [Acarina]

The effects of the eriophyid miteAceria ficus Cotte, the tetranychid miteTetranychus arabicus Attiah and castor-oil pollen on the development and fecundity of the phytoseiid predatorPhytoseius plumifer (C. & F.) were studied. The feeding capacity of all developmental stages ofP. plumifer onA. ficus was also considered. A. ficus was noted to be the more preferable prey to the predator rather thanT. arabicus. Pollen promoted a marked suppression in the predator's reproduction.     

The kinesin KIF4 mediates HBV/HDV entry through the regulation of surface NTCP localization and can be targeted by RXR agonists in vitro

Intracellular transport via microtubule-based dynein and kinesin family motors plays a key role in viral reproduction and transmission. We show here that Kinesin Family Member 4 (KIF4) plays an important role in HBV/HDV infection. We intended to explore host factors impacting the HBV life cycle that can be therapeutically addressed using siRNA library transfection and HBV/NLuc (HBV/NL) reporter virus infection in HepG2-hNTCP cells. KIF4 silencing resulted in a 3-fold reduction in luciferase activity following HBV/NL infection. KIF4 knockdown suppressed both HBV and HDV infection. Transient KIF4 depletion reduced surface and raised intracellular NTCP (HBV/HDV entry receptor) levels, according to both cellular fractionation and immunofluorescence analysis (IF). Overexpression of wild-type KIF4 but not ATPase-null KIF4 mutant regained the surface localization of NTCP and significantly restored HBV permissiveness in these cells. IF revealed KIF4 and NTCP colocalization across microtubule filaments, and a co-immunoprecipitation study revealed that KIF4 interacts with NTCP. KIF4 expression is regulated by FOXM1. Interestingly, we discovered that RXR agonists (Bexarotene, and Alitretinoin) down-regulated KIF4 expression via FOXM1-mediated suppression, resulting in a substantial decrease in HBV-Pre-S1 protein attachment to HepG2-hNTCP cell surface and subsequent HBV infection in both HepG2-hNTCP and primary human hepatocyte (PXB) (Bexarotene, IC₅₀ 1.89 ± 0.98 μM) cultures. Overall, our findings show that human KIF4 is a critical regulator of NTCP surface transport and localization, which is required for NTCP to function as a receptor for HBV/HDV entry. Furthermore, small molecules that suppress or alleviate KIF4 expression would be potential antiviral candidates targeting HBV and HDV entry.     

Role of cyanide production by Pseudomonas fluorescens CHA0 in the suppression of root-knot nematode, Meloidogyne javanica in tomato

Summary Pseudomonas fluorescens strain CHA0 produces hydrogen cyanide (HCN), a secondary metabolite that accounts largely for the biocontrol ability of this strain. In this study, we examined the role of HCN production by CHA0 as an antagonistic factor that contributes to biocontrol of Meloidogyne javanica, the root-knot nematode, in situ. Culture filtrate of CHA0, resulting from 1/10-strength nutrient broth yeast extract medium amended with glycine, inhibited egg hatch and caused mortality of M. javanica juveniles in vitro. The bacterium cultured under high oxygen-tension conditions exhibited better inhibitory effects towards nematodes, compared to its cultivation under excess oxygen situation. Growth medium amended with 0.50 or 1.0 mM FeEDDHA further improved hatch inhibition and nematicidal activity of the strain CHA0. Strain CHA77, an HCN-negative mutant, failed to exert such toxic effects, and in this strain, antinematode activity was not influenced by culture conditions. Exogenous cyanide also inhibited egg hatch and caused mortality of M. javanica juveniles in vitro. Strains CHA0 or CHA77 applied in unsterilized sandy-loam soil as drench, caused marked suppression of root-knot disease development incited by M. javanica in tomato seedlings. However, efficacy of CHA77 was noticeably lower compared to its wild type counterpart CHA0. An increased bioavailability of iron following EDTA application in soil substantially improved nematode biocontrol potential of CHA0 but not that of CHA77. Soil infestation with M. javanica eggs resulted in significantly lower nematode population densities and root-knot disease compared to the juveniles used as root-knot disease-inducing agents. Strain CHA0 significantly suppressed nematode populations and inhibited galling in tomato roots grown in soil inoculated with eggs or juveniles and treated with or without EDTA. Strain CHA0 exhibited greater biocontrol potential in soil inoculated with eggs and treated with EDTA. To demonstrate that HCN synthesis by the strain CHA0 acts as the inducing agent of systemic resistance in tomato, efficacy of the strain CHA0 was compared with CHA77 in a split root trial. The split-root experiment, guaranteeing a spatial separation of the inducing agent and the challenging pathogen, showed that HCN production by CHA0 is not crucial in the induction of systemic resistance in tomato against M. javanica, because the HCN-negative-mutant CHA77 induced the same level of resistance as the wild type but exogenous cyanide in the form of KCN failed to trigger the resistance reaction. In the root section where both nematode and the bacterium were present, strain CHA0 reduced nematode penetration to a greater extent than CHA77, suggesting that for effective control of M. javanica, a direct contact between HCN-producing CHA0 and the nematode is essential.