Serum C3d levels in tropical pulmonary eosinophilia

BACKGROUND & OBJECTIVES

Results of earlier studies to evaluate the possible role of complement system in tropical pulmonary eosinophilia (TPE) using classical methods like serum haemolyte component CH50, C3 and C4 levels were inconclusive. In this study we determined levels of serum C3d which is a catabolic fragment of C3, to find out any direct evidence of activation of the complement system in TPE.

METHODS

The study population consisted of 3 groups. Group A consisted of 37 patients with well characterized TPE. In group B, 26 patients with pulmonary eosinophilia had similar respiratory and haemotological features as in Group A but had associated worm infestation in stool. The control group consisted of 39 healthy volunteers. Serum C3d levels were determined by sandwich ELISA technique.

RESULTS

The serum C3d levels in TPE patients were not significantly different from those of the patients of group B or the normal controls.

INTERPRETATION & CONCLUSIONS

Absence of significant change in serum C3d goes against the possibility of complement activation in TPE. Results of our study suggest that complement system is unlikely to play a pivotal role in pathogenesis of TPE.

Optimal sampling strategy and core collection size of Andean tetraploid potato based on isozyme data - a simulation study

Selection of an appropriate sampling strategy is an important prerequisite to establish core collections of appropriate size in order to adequately represent the genetic spectrum and maximally capture the genetic diversity in available crop collections. We developed a simulation approach to identify an optimal sampling strategy and core-collection size, using isozyme data from a CIP germplasm collection on an Andean tetraploid potato. Five sampling strategies, constant (C), proportional (P), logarithmic (L), square-root (S) and random (R), were tested on isozyme data from 9,396 Andean tetraploid potato accessions characterized for nine isozyme loci having a total of 38 alleles. The 9,396 accessions, though comprising 2,379 morphologically distinct accessions, were found to represent 1,910 genetically distinct groups of accessions for the nine isozyme loci using a sort-and-duplicate-search algorithm. From each group, one accession was randomly selected to form a genetically refined entire collection (GREC) of size 1,910. The GREC was used to test the five sampling strategies. To assess the behavior of the results in repeated sampling, k = 1,500 and 5,000 independent random samples (without replacement) of admissible sizes n = 50(50)1,000 for each strategy were drawn from GREC. Allele frequencies (AF) for the 38 alleles and locus heterozygosity (LH) for the nine loci were estimated for each sample. The goodness of fit of samples AF and LH with those from GREC was tested using the chi(2) test. A core collection of size n = 600, selected using either the P or the R sampling strategy, was found adequately to represent the GREC for both AF and LH. As similar results were obtained at k = 1,500 and 5,000, it seems adequate to draw 1,500 independent random samples of different sizes to test the behavior of different sampling strategies in order to identify an appropriate sampling approach, as well as to determine an optimal core collection size.

Reverse micellar extraction for downstream processing of proteins/enzymes

New developments in the area of downstream processing are, hopefully, to fulfill the promises of modern biotechnology. The traditional separation processes such as chromatography or electrophoresis can become prohibitively expensive unless the product is of high value. Hence, there is a need to develop efficient and cost-effective downstream processing methods. Reverse micellar extraction is one such potential and a promising liquid-liquid extraction technique, which has received immense attention for isolation and purification of proteins/enzymes in the recent times. This technique is easy to scale-up and offers continuous operation. This review, besides briefly considering important physico-chemical and biological aspects, highlights the engineering aspects including mass transfer, mathematical modeling, and technology development. It also discusses recent developments in reverse micellar extraction such as affinity based separations, enzymatic reactions in reverse micelles coupled with membrane processes, reverse micellar extraction in hollow fibers, etc. Special emphasis has been given to some recent applications of this technique.

Lipase-catalyzed synthesis of isoamyl butyrate. A kinetic study

Kinetics of lipase-catalyzed esterification of butyric acid and isoamyl alcohol have been investigated. The reaction rate could be described in terms of the Michaelis-Menten equation with a Ping-Pong Bi-Bi mechanism and competitive inhibition by both the substrates. No evidence of any significant diffusional limitations was detected that could affect the kinetics. The values of the apparent kinetic parameters were computed as: V(max)=11.72 micromol/min/mg; K(M, Acid)=0.00303 M; K(M, Alcohol)=0.00306 M; K(i, Acid)=1.05 M; and K(i, Alcohol)=6.55 M. This study indicates a competitive enzyme inhibition by butyric acid during lipase-catalyzed esterification reaction. Butyric acid, being a short-chain polar acid, concentrates in the microaqueous layer and causes a pH drop in the enzyme microenvironment leading to enzyme inactivation. Butyric acid binds to acyl-enzyme complex unproductively to yield a dead-end intermediate that can no longer give rise to an ester. High concentration of butyric acid gave rise to inactivation of the biocatalyst in addition to dead-end inhibition.

Enzymatic synthesis of isoamyl acetate using immobilized lipase from Rhizomucor miehei

The effects of important reaction parameters for enhancing isoamyl acetate formation through lipase-catalyzed esterification of isoamyl alcohol were investigated in this study. Increase in substrate (acid) concentration led to decrease in conversions. A critical enzyme concentration of 3 g l(-1) was detected for a substrate concentration of 0.06 M (each of alcohol and acid). Solvents with partition coefficient higher than 1000 (log P>3.0) supported enzyme activity to give high conversions. Acetic acid at higher concentrations could not be esterified easily probably owing to its role in lowering the microaqueous pH of the enzyme. Extraneous water/buffer addition decreased the isoamyl acetate yields slightly ( approximately 10%) at 0.005-0.01% v/v of the reaction mixture and drastically (>40%) at above 0.01% v/v. Buffer saturation of the organic solvent employed improved esterification (upto two-fold), particularly at moderately higher substrate concentrations (>0.18 M). Employing acetic anhydride instead of acetic acid resulted in a two-fold increase in the yields (at 0.25 M substrate). Use of excess nucleophile (alcohol) concentration by increasing the alcohol/acid molar ratio resulted in higher conversions in shorter duration (upto eight-fold even at 1.5 M acetic acid). Yields above 80% were achieved with substrate concentrations as high as 1.5 M and more than 150 g l(-1) isoamyl acetate concentrations were obtained employing a relatively low enzyme concentration of 10 g l(-1). The operational stability of lipase was also observed to be reasonably high enabling ten reuses of the biocatalyst.

Simultaneous saccharification and fermentation of lignocellulosic wastes to ethanol using a thermotolerant yeast

Simultaneous saccharification and fermentation (SSF) studies were carried out to produce ethanol from lignocellulosic wastes (sugar cane leaves and Antigonum leptopus leaves) using Trichoderma reesei cellulase and yeast cells. The ability of a thermotolerant yeast, Kluyveromyces fragilis NCIM 3358, was compared with Saccharomyces cerevisiae NRRL-Y-132. K. fragilis was found to perform better in the SSF process and result in high yields of ethanol (2.5-3.5% w/v) compared to S. cerevisiae (2.0-2.5% w/v). Increased ethanol yields were obtained when the cellulase was supplemented with beta-glucosidase. The conversions with K. fragilis were completed in a short time. The substrates were in the following order in terms of fast conversions: Solka floc > A. leptopus > sugar cane.

Optimization of simultaneous saccharification and fermentation for the production of ethanol from lignocellulosic biomass

Simultaneous saccharification and fermentation (SSF) of alkaline hydrogen peroxide pretreated Antigonum leptopus (Linn) leaves to ethanol was optimized using cellulase from Trichoderma reesei QM-9414 (Celluclast from Novo) and Saccharomyces cerevisiae NRRL-Y-132 cells. Response surface methodology (RSM) and a three-level four-variable design were employed to evaluate the effects of SSF process variables such as cellulase concentration (20-100 FPU/g of substrate), substrate concentration (5-15% w/v), incubation time (24-72 h), and temperature (35-45 degrees C) on ethanol production efficiency. Cellulase and substrate concentrations were found to be the most significant variables. The optimum conditions arrived at are as follows: cellulase = 100 FPU/g of substrate, substrate = 15% (w/v), incubation time = 57.2 h, and temperature = 38.5 degrees C. At these conditions, the predicted ethanol yield was 3.02% (w/v) and the actual experimental value was 3.0% (w/v).