A New Method for Mercury Removal

A method is desibed for the removal of mercury from solution by using the off-gas produced from aerobic cultures of Klebsiella pneumoniae M426. Cells growing in Hg-supplemented medium produced a black precipitate containing mercury and sulphur. The ratio of Hg:S was determined as ~1:1 by analysis using proton-induced X-ray emission, suggesting precipitation of HgS within the culture. The outlet gases produced by a mercury-unsupplemented aerated culture were bubbled into an external chamber supplemented with up to 10 mg HgCl₂/ml. A yellowish-white precipitate formed, corresponding to 99% removal of the mercury from solution within 120 min. Energy dispersive X-ray microanalysis showed that this metal precipitate consisted of mercury, carbon and sulphur. Formation of mercury carbonate was discounted since similar precipitation occurred at pH 2 and no oxygen was detected in the solid, which gave an X-ray powder pattern suggesting an amorphous material, with no evidence of HgS. Precipitation of mercury with a volatile organosulphur compound is suggested. Bio-precipitation of heavy metals by using culture off-gas is a useful approach because it can be used with concentrated or physiologically incompatible solutions. Since the metal precipitate is kept separate from the bacterial biomass, it can be managed independently.     

Influences of Chronic Mild Stress Exposure on Motor,Non-Motor Impairments and Neurochemical Variables in Specific Brain Areas of MPTP/Probenecid Induced Neurotoxicity in Mice

Parkinson''s disease (PD) is regarded as a movement disorder mainly affecting the elderly population and occurs due to progressive loss of dopaminergic (DAergic) neurons in nigrostriatal pathway. Patients suffer from non-motor symptoms (NMS) such as depression, anxiety, fatigue and sleep disorders, which are not well focussed in PD research. Depression in PD is a predominant /complex symptom and its pathology lies exterior to the nigrostriatal system. The main aim of this study is to explore the causative or progressive effect of chronic mild stress (CMS), a paradigm developed as an animal model of depression in1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (25 mg/kg. body wt.) with probenecid (250 mg/kg, s.c.) (MPTP/p) induced mice model of PD. After ten i.p. injections (once in 3.5 days for 5 weeks) of MPTP/p or exposure to CMS for 4 weeks, the behavioural (motor and non-motor) impairments, levels and expressions of dopamine (DA), serotonin (5-HT), DAergic markers such as tyrosine hydroxylase (TH), dopamine transporter (DAT), vesicular monoamine transporters—2 (VMAT 2) and α-synuclein in nigrostriatal (striatum (ST) and substantia nigra (SN)) and extra-nigrostriatal (hippocampus, cortex and cerebellum) tissues were analysed. Significantly decreased DA and 5-HT levels, TH, DAT and VMAT 2 expressions and increased motor deficits, anhedonia-like behaviour and α-synuclein expression were found in MPTP/p treated mice. Pre and/or post exposure of CMS to MPTP/p mice further enhanced the MPTP/p induced DA and 5-HT depletion, behaviour abnormalities and protein expressions. Our results could strongly confirm that the exposure of stress after MPTP/p injections worsens the symptoms and neurochemicals status of PD.     

Multiplexed echo planar imaging for sub-second whole brain FMRI and fast diffusion imaging

Echo planar imaging (EPI) is an MRI technique of particular value to neuroscience, with its use for virtually all functional MRI (fMRI) and diffusion imaging of fiber connections in the human brain. EPI generates a single 2D image in a fraction of a second; however, it requires 2-3 seconds to acquire multi-slice whole brain coverage for fMRI and even longer for diffusion imaging. Here we report on a large reduction in EPI whole brain scan time at 3 and 7 Tesla, without significantly sacrificing spatial resolution, and while gaining functional sensitivity. The multiplexed-EPI (M-EPI) pulse sequence combines two forms of multiplexing: temporal multiplexing (m) utilizing simultaneous echo refocused (SIR) EPI and spatial multiplexing (n) with multibanded RF pulses (MB) to achieve m×n images in an EPI echo train instead of the normal single image. This resulted in an unprecedented reduction in EPI scan time for whole brain fMRI performed at 3 Tesla, permitting TRs of 400 ms and 800 ms compared to a more conventional 2.5 sec TR, and 2-4 times reductions in scan time for HARDI imaging of neuronal fibertracks. The simultaneous SE refocusing of SIR imaging at 7 Tesla advantageously reduced SAR by using fewer RF refocusing pulses and by shifting fat signal out of the image plane so that fat suppression pulses were not required. In preliminary studies of resting state functional networks identified through independent component analysis, the 6-fold higher sampling rate increased the peak functional sensitivity by 60%. The novel M-EPI pulse sequence resulted in a significantly increased temporal resolution for whole brain fMRI, and as such, this new methodology can be used for studying non-stationarity in networks and generally for expanding and enriching the functional information.     

Application of Box-Behnken Design to Hybrid Electrokinetic-Adsorption Removal of Mercury from Contaminated Saline-Sodic Clay Soil

A hybrid electrokinetic-adsorption (HEKA) technique using uniform electric field and granular activated carbon (GAC) produced from date palm pits was investigated for the removal of mercury from natural saline-sodic clay heavily contaminated with heavy metals, phenol, and kerosene. Response surface methodology (RSM) was employed to model, optimize, and interpret the results obtained with the aid of Design Expert software. According to the Box-Behnken experimental design, 15 experiments were conducted each with residence time of three weeks. The effects of voltage gradient (0.2–1 V/cm), initial Hg concentration (mg/Kg), and polarity reversal interval (0-48 hours) on Hg removal efficiency and energy consumed for Hg removal were investigated. Respectively, the responses fitted reduced cubic (R² = 99.3%) and quadratic models (R² = 92.3%) with the overall relative contributions of the investigated parameters on the responses following the order: voltage gradient > initial Hg concentration > polarity reversal interval based on analysis of variance (ANOVA). The optimal conditions obtained with desirability of 90% aimed at maximizing Hg removal were 24 hours polarity reversal interval, 0.2 V/cm voltage gradient, and 100 mg/kg initial Hg concentration. This optimum operating condition yielded good removal of Hg (99.5%) at reduced energy consumption of 50.1kWh.m^?3mg^?1. Experimental validation of the models showed good prediction of Hg removal efficiency (0.0368% prediction error). The results presented herein suggest that HEKA technology could be utilized effectively for the removal of Hg from contaminated, low permeable soils under extreme soil and contamination conditions.     

Application of endophytic bacteria for the biocontrol of Rhizoctonia solani (Cantharellales: ceratobasidiaceae) damping-off disease in cotton seedlings

The antifungal potentialities of three endophytic bacterial strains, Stenotrophomonas maltophila H8 (Xanthomonadales: Xanthomonadaceae), Pseudomonas aeruginosa H40 (Pseudomonadales: Pseudomonadaceae) and Bacillus subtilis H18 (Bacillales: Bacillaceae) were evaluated against the phytopathogenic fungus Rhizoctonia solani in cotton seedlings under greenhouse conditions. The bacterial strains were applied as a soil drench or talc-based bioformulation in R. solani-infested soil and non-infested soil. Results indicated that the soil drench treatment was more efficient than talc-based bioformulation. A significant increase of seed emergence and seedling survival with a clear reduction of disease severity was achieved with the endophytic bacterial treatments. At the same time, the fresh weight, dry weight, shoot length and root length of the treated plants were markedly enhanced. Moreover, there was an apparent induction of the antioxidant enzymes (peroxidase, polyphenol oxidase and catalase) of the treated seedlings. Gas chromatography–mass spectrometry revealed the presence of various bioactive compounds in the bacterial supernatant. The antagonistic activity of the bacterial strains against R. solani was attributed to their capability to produce a broad spectrum of antifungal compounds in addition to bioactive molecules that can trigger the systemic resistance in the infected seedlings.     

Molecular Dynamics Analysis of a Novel β3 Pro189Ser Mutation in a Patient with Glanzmann Thrombasthenia Differentially Affecting αIIbβ3 and αvβ3 Expression

Mutations in ITGA2B and ITGB3 cause Glanzmann thrombasthenia, an inherited bleeding disorder in which platelets fail to aggregate when stimulated. Whereas an absence of expression or qualitative defects of αIIbβ3 mainly affect platelets and megakaryocytes, αvβ3 has a widespread tissue distribution. Little is known of how amino acid substitutions of β3 comparatively affect the expression and structure of both integrins. We now report computer modelling including molecular dynamics simulations of extracellular head domains of αIIbβ3 and αvβ3 to determine the role of a novel β3 Pro189Ser (P163S in the mature protein) substitution that abrogates αIIbβ3 expression in platelets while allowing synthesis of αvβ3. Transfection of wild-type and mutated integrins in CHO cells confirmed that only αvβ3 surface expression was maintained. Modeling initially confirmed that replacement of αIIb by αv in the dimer results in a significant decrease in surface contacts at the subunit interface. For αIIbβ3, the presence of β3S163 specifically displaces an α-helix starting at position 259 and interacting with β3R261 while there is a moderate 11% increase in intra-subunit H-bonds and a very weak decrease in the global H-bond network. In contrast, for αvβ3, S163 has different effects with β3R261 coming deeper into the propeller with a 43% increase in intra-subunit H-bonds but with little effect on the global H-bond network. Compared to the WT integrins, the P163S mutation induces a small increase in the inter-subunit fluctuations for αIIbβ3 but a more rigid structure for αvβ3. Overall, this mutation stabilizes αvβ3 despite preventing αIIbβ3 expression.     

Correlation between CMV genotypes,multiple infections with herpesviruses (HHV-6, 7) and development of CMV disease in kidney recipients in Kuwait

The possible correlation between cytomegalovirus, human herpesvirus types 6, 7 and cytomegalovirus-related clinical symptoms was studied in kidney transplant patients in Kuwait. Cytomegalovirus infection was diagnosed using the pp65 antigenemia assay. DNA of cytomegalovirus was detected by nested polymerase chain reaction (nested-PCR). PCR was also used to amplify the genes coding for structural proteins of human herpesvirus-6 (240 bp) and human herpesvirus-7 (186 bp). Glycoprotein B genotypes of cytomegalovirus were determined by restriction fragment length polymorphism. The average number of cells positive for cytomegalovirus pp65 antigen showed a steady increase with the severity of the cytomegalovirus-related symptoms. Furthermore, cytomegalovirus pp65 antigen positivity was significantly more frequent among recipients of cadaver kidney (45.5%) than among those who received live related kidneys (22.6%). Cytomegalovirus gB genotype 1 was detected more frequently (P<0.036) in recipients with live related donor kidney (38%) than in patients of cadaver kidney (13%). The genome of human herpesvirus-6 was detected at the same rate in patients with or without cytomegalovirus-related symptoms. However, the genome of human herpesvirus-7 was detected significantly more frequently (P<0.0001) in asymptomatic patients (41.7%) than in recipients with symptomatic cytomegalovirus infection (17%). We conclude that cytomegalovirus gB genotypes are not associated with the outcome of a cytomegalovirus infection in kidney transplant patients, that human herpesvirus-6 does not play a role in cytomegalovirus pathogenesis and that the role of human herpesvirus-7 in cytomegalovirus-related morbidity in kidney recipients remains unclear.