Effect of exogenous 5-hydroxytryptamine on pathogenicity of Entamoeba histolytica in experimental animals

In an effort to find out the mechanism(s) operative in enhancing the pathogenicity of E. histolytica in hosts under heat stress reported earlier, effect of 5-hydroxytryptamine (5-HT) on the virulence of the parasite was examined in just weaned Charles Foster strain of albino rats. Pathogenicity of 10 strains of E. histolytica, from various forms of intestinal amoebiasis, grown in modified Boeck and Drbohlav's medium was assessed by caecal scoring. Administration of 5-HT in infected animals significantly enhanced the pathogenicity of all the seven strains tested. Treatment of the host with the 5-HT precursor L-tryptophan also increased the caecal scores examined with three strains of E. histolytica. Prior blocking of tissue 5-HT receptors by administration of methysergide almost completely abolished the pathogenicity enhancing effect of 5-HT treatment. This suggested that 5-HT itself and not any of its metabolites was responsible for the observed increase in pathogenicity of E. histolytica on 5-HT treatment of the host.     

High-level expression of three members of the murine angiogenin family in Escherichia coli and purification of the recombinant proteins.

Angiogenin (Ang) is a small basic protein which belongs to the pancreatic ribonuclease superfamily. It potently induces the formation of new blood vessels and has emerged as a promising anticancer target. Mice possess genes encoding one ortholog (mAng) and three homologs of Ang, designated angiogenin-related protein (mAngrp), angiogenin-3 (mAng-3), and angiogenin-4 (mAng-4). Structural and functional study of these homologs has been hampered by the low yield of protein from the existing heterologous expression system. In the experiments described, we used a pET expression vector to express these proteins in the cytoplasm of Escherichia coli BL21-CodonPlus(DE3)-RIL cells, whereupon substantial amounts of each accumulated in the form of insoluble aggregates. The proteins were renatured using an arginine-assisted procedure and subsequently purified by cation-exchange chromatography and reversed-phase HPLC; each purified protein was shown to be enzymatically active toward tRNA. The yields of pure mAngrp and mAng-3 were 7.6 and 12 mg/liter culture, respectively, representing substantial increases over previously reported experiments. This is also the first report of the expression and purification of mAng-4, obtained here in a yield of 30 mg/liter culture. The ready availability of milligram quantities of these proteins will enable further functional studies and high-resolution structural analyses to be conducted.     

On the reactivity of carboxyl groups of ribonuclease-A in anhydrous methanol.

The esterification of Ribonuclease-A in methanol/0.1 M hydrochloric acid has been studied by measuring the decrease in the number of titratable groups of the protein and estimating the amount of methanol incorporated. Esterification of nearly five of the 11 free carboxyl groups of the protein resulted in almost complete inactivation of the enzyme. The initial products of esterification have been chromatographed on Amberlite columns, and five partially active methyl ester derivatives of Ribonuclease-A have been isolated. The dimethyl ester, the initial product of esterification with reduced catalytic activity, has the carboxyl groups of Glu-49 and Asp-53 modified. Even in the non-aqueous solvent, as in the native structure of the protein in aqueous solution, these carboxyl groups are the fast reacting ones. Subsquently, the esterification reaction appears to proceed preferentially at the C-terminal region of the molecule. Comparison of the reactivities of carboxyl groups of Ribonuclease-A in acidic methanol to that known in aqueous solutions (with carbodiimides) suggests that the structure of Ribonuclease-A in the non-aqueous solvent resembles, at least in part, the structure in aqueous environment.     

Heart rate variability changes during high frequency yoga breathingand breath awareness

Background  

Pre and post comparison after one minute of high frequency yoga breathing (HFYB) suggested that the HFYB modifies the autonomic status by increasing sympathetic modulation, but its effect during the practice was not assessed.     

Hexa-thiocarbamoyl Phenyl PEG5K Hb: Vasoactivity and Structure

A new hexaPEGylated hemoglobin, (TCP-PEG5K)₆-Hb (TCP, thiocarbamoyl phenyl) has been developed using PEG-phenyl-isothiocyanate and its vasoactivity and structure has been investigated. Of the six PEG5K chains of (TCP-PEG5K)₆-Hb, 4 are conjugated to the α-amino groups of Hb, and the other 2 chains are distributed on ε-amino groups, identified as Lys-40(α) (~45%), Lys-56(α) (~25%), and Lys-8(β) (~24%). The studies with hamster infused with a bolus of a 4 gm % solution of (TCP-PEG5K)₆-Hb equivalent to 10% of their blood volume have established that this new hexaPEGylated Hb is vasoinactive. The viscosity and the colloidal osmotic pressure of (TCP-PEG5K)₆-Hb at 4% is 1.9 cP and 69.7 mmHg, respectively. The molecular radius of (TCP-PEG5K)₆-Hb is about 4.6 nm and is significantly smaller than hexaPEGylated Hbs developed using other direct and extension arm facilitated PEGylation platform. The presence of an outside the central cavity intramolecular crosslink, succinimidophenyl-PEG2K between Cys-93(β, β′) in (TCP-PEG5K)₆-ββ-Hb strongly impacts its solution properties. These patterns of influence suggest that the inter-dimeric interactions in (TCP-PEG5K)₆-Hb is weakened just as with other direct PEGylation platforms, and (SP-PEG5K)₆-Hb generated by EAF-PEGylation is unique in not inducing this effect. A comparison of the properties of hexaPEGylated Hbs establishes that rigidity of the conjugation linkage between PEG and Hb plays a significant influence on the resultant dictating solution properties and/structure/conformation of PEG-Hb adduct.     

Aerobic reduction of perchlorate by bacteria isolated in Kerala, South India

Possibility of perchlorate reduction by microbes raises hope for an eco-friendly mode of degradation of this toxic rocket fuel. This study reports 3 isolates (A1, A2 and A3) capable of molybdenum-independent degradation of perchlorate under aerobic conditions. The rate of degradation was the highest when perchlorate concentration was 17 mM, and then 3.2 mM, 4.7 mM and 4.1 mM of perchlorate was reduced by isolates A1, A2 and A3 (respectively) after 72 h at 28°C under aerobic conditions. Presence of perchlorate at a concentration higher than 17 mM resulted in some inhibition of perchlorate reduction. 16S ribosomal RNA gene analysis revealed isolate A1 to bePseudomonas stutzeri (Proteobacteria) while isolates A2 ad A3 where found to belong to the genusArthrobacter (Actinobacteria). The study, apart from demonstrating ribotyping as a rapid method of identification of economically important soil microbes, also raised prospects for using artificial consortia for environmental degradation of perchlorate, without apparent domination ofDechloromonas spp. (a group of microbes known for perchlorate remediation in the environment).     

Woody plant encroachment alters soil hydrological properties and reduces downward flux of water in tallgrass prairie

Plant and Soil - Plant and soil interact to shape ecosystem properties, processes and services provided. Changes in ecosystem productivity, biogeochemical cycling and plant herbivore interactions...