A comparison of transketolase assay and transketolase and lactate dehydrogenase activity levels in whole blood and red cell hemolysates and in leukocytes

1. A study was made of transketolase activity in red and white blood cells and of conditions for assay for transketolase activity and for assessment of the "TPP effect" in human and rat blood. 2. The ratio of the transketolase activity in white cells to that in red cells varied between 23 and 93. 3. Red cells or white cells can both be used for assessment of transketolase activity and the "TPP effect", but the best source for evaluation of transketolase activity and the percent change on addition of thiamin diphosphate appears to be whole blood.     

Post-exposure temperature influence on the toxicity of conventional and new chemistry insecticides to green lacewing Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae)

Chrysoperla carnea (Stephens) is an important biological control agent currently being used in many integrated pest management (IPM) programs to control insect pests. The effect of post-treatment temperature on insecticide toxicity of a spinosyn (spinosad), pyrethroid (lambda cyhalothrin), organophosphate (chlorpyrifos) and new chemistry (acetamiprid) to C. carnea larvae was investigated under laboratory conditions. Temperature coefficients of each insecticide tested were evaluated. From 20 to 40 °C, toxicity of lambda cyhalothrin and spinosad decreased by 2.15- and 1.87-fold while toxicity of acetamiprid and chlorpyrifos increased by 2.00 and 1.79-fold, respectively. The study demonstrates that pesticide effectiveness may vary according to environmental conditions. In cropping systems where multiple insecticide products are used, attention should be given to temperature variation as a key factor in making pest management strategies safer for biological control agents. Insecticides with a negative temperature coefficient may play a constructive role to conserve C. carnea populations.     

Discerning of Rice Landraces (Oryza sativa L.) for Morpho-physiological,Antioxidant Enzyme Activity,and Molecular Markers’ Responses to Induced Salt Stress at the Seedling Stage

Salinity has been identified as key abiotic stress factor limiting rice production in many countries around the globe, including Bangladesh. In the present study, we examined the effects of salt-induced toxicity on growth of rice landraces for screening salt-tolerant genotypes by assessing morpho-physiological, biochemical, and molecular responses. Screening of 28 rice genotypes at seedling stage was performed at 12 dS m⁻¹ salinity level in hydroponic media. Most of the rice genotypes showed an apparent reduction in growth traits, while a fewer showed less reduction under salinity stress. Euclidean clustering and heatmap based on morpho-physiological parameters dissected rice genotypes into three major clusters, viz., susceptible, moderately tolerant, and tolerant. Results of cluster analysis revealed Nonabokra, Hogla, Ghunsi, Holdegotal, Nonabokra, and Kanchon as salt-tolerant rice genotypes. These genotypes also were grouped using three microsatellite markers, viz., RM493, RM3412b, and RM140 that were closely linked to saltol QTL showed Hogla, Ghunsi, Holdegotal, Nonabokra, Kanchon, BINA dhan-8, and BINA dhan-10 as salt-tolerant genotypes considering genetic similarity in dendrogram. The positive relationships of Na⁺/K⁺ ratio with hydrogen peroxide (H₂O₂) and malondialdehyde (MDA), and antioxidant enzymes’ activity in the tolerant rice genotypes indicated their importance for improving salinity tolerance. The salt-tolerant landraces showed lower Na⁺/K⁺ ratio, high proline accumulation, lower H₂O₂ accumulation and MDA content, and higher catalase and ascorbate peroxidase activities. Higher antioxidant enzymes’ activity and lower H₂O₂ accumulation in tolerant genotypes indicate their abilities to fight against oxidative stress. Based on all morpho-physiological clustering, biochemical response, and molecular dendrogram, Nonabokra, Hogla, Ghunsi, Holdegotal, and Kanchon were identified as the salt-tolerant landraces. Therefore, these identified salt-tolerant landraces could be useful to improve breeding program for the development of salt-tolerant high-yielding rice cultivars in future.

     

Inactivation of B12 and folate coenzymes by butyl nitrite as observed by NMR: implications on one-carbon transfer mechanism

The effects of butyl nitrite, a frequently used recreational drug, on methyl cobalamin and 5-methyl tetrahydrofolate were investigated by using 1H and 31P NMR spectroscopies. While no effect could be observed in organic solvents, strong interactions of butyl nitrite with the methyl cobalamin and 5-methyl tetrahydrofolate were found to occur in water. Butyl nitrite decomposes in water generating H+ and NO-2. The former protonates to give the "base-off" configuration of methyl cobalamin while the Co-CH3 bond is cleaved. Similarly, the methyl group at the 5N position and the pyrazine ring of 5-methyl tetrahydrofolate were found to be affected by butyl nitrite. The overall interaction of butyl nitrite with both coenzymes shows displacement of the methyl group and derivatization or destruction of the coenzymes that may lead to deficiencies of both B-12 and/or folates.     

Carboxyl terminal region of the MukB protein in Escherichia coli is essential for DNA binding activity

Abstract The purified MukB protein of Escherichia coli has DNA binding activity and nucleotide binding activity. We have isolated a mutation, mukB1013 , causing a substitution of valine at position 1379 to leucine. This mutant MukB protein was defective for DNA binding, while the ATP binding activity remained unaffected. A truncated MukB protein that is short of 109 amino acids from the C-terminus failed to bind DNA.     

Timing of enteral feeding in cerebral malaria in resource-poor settings: a randomized trial

Background

Early start of enteral feeding is an established treatment strategy in intubated patients in intensive care since it reduces invasive bacterial infections and length of hospital stay. There is equipoise whether early enteral feeding is also beneficial in non-intubated patients with cerebral malaria in resource poor settings. We hypothesized that the risk of aspiration pneumonia might outweigh the potential benefits of earlier recovery and prevention of hypoglycaemia.

Method and Findings

A randomized trial of early (day of admission) versus late (after 60 hours in adults or 36 hours in children) start of enteral feeding was undertaken in patients with cerebral malaria in Chittagong, Bangladesh from May 2008 to August 2009. The primary outcome measures were incidence of aspiration pneumonia, hypoglycaemia and coma recovery time. The trial was terminated after inclusion of 56 patients because of a high incidence of aspiration pneumonia in the early feeding group (9/27 (33%)), compared to the late feeding group (0/29 (0%)), p = 0.001). One patient in the late feeding group, and none in the early group, had hypoglycaemia during admission. There was no significant difference in overall mortality (9/27 (33%) vs 6/29 (21%), p = 0.370), but mortality was 5/9 (56%) in patients with aspiration pneumonia.

Conclusions

In conclusion, early start of enteral feeding is detrimental in non-intubated patients with cerebral malaria in many resource-poor settings. Evidence gathered in resource rich settings is not necessarily transferable to resource-poor settings.

Trial Registration

Controlled-Trials.com ISRCTN57488577     

Performance of diagnostic biomarkers in predicting liver fibrosis among hepatitis C virus-infected Egyptian children

The aim of the present study was to identify specific markers that mirror liver fibrosis progression as an alternative to biopsy when biopsy is contraindicated, especially in children. After liver biopsies were performed, serum samples from 30 hepatitis C virus (HCV) paediatric patients (8-14 years) were analysed and compared with samples from 30 healthy subjects. All subjects were tested for the presence of serum anti-HCV antibodies. Direct biomarkers for liver fibrosis, including transforming growth factor-β1, tissue inhibitor of matrix metalloproteinase-1 (TIMP-1), hyaluronic acid (HA), procollagen type III amino-terminal peptide (PIIINP) and osteopontin (OPN), were measured. The indirect biomarkers aspartate and alanine aminotransferases, albumin and bilirubin were also tested. The results revealed a significant increase in the serum marker levels in HCV-infected children compared with the healthy group, whereas albumin levels exhibited a significant decrease. Significantly higher levels of PIIINP, TIMP-1, OPN and HA were detected in HCV-infected children with moderate to severe fibrosis compared with children with mild fibrosis (p < 0.05). The diagnostic accuracy of these direct biomarkers, represented by sensitivity, specificity and positive predictive value, emphasises the utility of PIIINP, TIMP-1, OPN and HA as indicators of liver fibrosis among HCV-infected children.     

Characterization of a Cross-Reactive,Immunodominant and HLA-Promiscuous Epitope of Mycobacterium tuberculosis-Specific Major Antigenic Protein PPE68

PPE68 (Rv3873), a major antignic protein encoded by Mycobacteriun tuberculosis-specific genomic region of difference (RD)1, is a strong stimulator of peripheral blood mononuclear cells (PBMCs) obtained from tuberculosis patients and Mycobacterium bovis bacillus Calmette Guerin (BCG)-vaccianted healthy subjects in T helper (Th)1 cell assays, i.e. antigen-induced proliferation and interferon-gamma (IFN-γ) secretion. To confirm the antigen-specific recognition of PPE68 by T cells in IFN-γ assays, antigen-induced human T-cell lines were established from PBMCs of M. Bovis BCG-vaccinated and HLA-heterogeneous healthy subjects and tested with peptide pools of RD1 proteins. The results showed that PPE68 was recognized by antigen-specific T-cell lines from HLA-heteregeneous subjects. To further identify the immunodominant and HLA-promiscuous Th1-1 cell epitopes present in PPE68, 24 synthetic peptides covering the sequence of PPE68 were indivdually analyzed for HLA-DR binding prediction analysis and tested with PBMCs from M. bovis BCG-vaccinated and HLA-heterogeuous healthy subjects in IFN-γ assays. The results identified the peptide P9, i.e. aa 121-VLTATNFFGINTIPIALTEMDYFIR-145, as an immunodominant and HLA-DR promiscuous peptide of PPE68. Furthermore, by using deletion peptides, the immunodominant and HLA-DR promiscuous core sequence was mapped to aa 127-FFGINTIPIA-136. Interestingly, the core sequence is present in several PPE proteins of M. tuberculosis, and conserved in all sequenced strains/species of M. tuberculosis and M. tuberculosis complex, and several other pathogenic mycobacterial species, including M. leprae and M. avium-intracellulalae complex. These results suggest that the peptide aa 121–145 may be exploited as a peptide-based vaccine candidate against tuberculosis and other mycobacterial diseases.     

OPTIMAL GROWTH CONDITIONS AND ANTIOXIDATIVE ACTIVITIES OF CYLINDROTHECA CLOSTERIUM (BACILLARIOPHYCEAE)1

We isolated the unialgal strain of Cylindotheca closterium (Ehrenb.) Reimann et J. C. Lewin and produced an axenic strain using an antibiotic cocktail of enriched f/2 artificial seawater medium. The optimal growth conditions were estimated under 27 different combinations of temperature, salinity, and nutrients, and mass culture was performed based on the best specific growth conditions. Its antioxidant activities were determined from the extracts of methanol, water, and enzymes (proteases and carbohydrases). The maximum specific growth rate (μ_max) varied from 0.63 to 0.97 · d^?1. The maximum cell density was 7.20 × 10⁴ cells · mL^?1, while the μ_max was 0.82 · d^?1 in culture conditions of 20°C, 30 psu (practical salinity unit), and “F” nutrient concentrations on day 10 of the culture period. The scavenging rates for 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) free radical were 72.5% and 69.4% from Viscozyme and methanol extracts, respectively. The enzymatic extracts of C. closterium prepared by the hydrolyses of Amyloglucosidase (AMG) and Viscozyme showed 45.8% and 45.5% nitric‐oxide‐scavenging rates, slightly lower than the activity of alpha‐tocopherol (α‐tocopherol) but similar to butylated hydroxytoluene (BHT). The extract from methanol and water showed 44.8% and 44.4% scavenging rates, statistically similar with BHT. The metal‐chelating activities of the Kojizyme, Alcalase, methanol, Viscozyme, and Neutrase extracts were 67.1, 53.9, 53.2, 52.1, and 50.2 %, respectively, five to six times higher than the commercial antioxidants. The AMG, Viscozyme, and Neutrase extracts showed a remarkable linoleic acid peroxidation inhibition, which was higher than BHT and statistically similar with α‐tocopherol.