Jasmina Khanam

Antibiotic Resistance, Virulence Gene, and Molecular Profiles of Shiga Toxin-Producing Escherichia coli Isolates from Diverse Sources in Calcutta, India

ABSTRACT Antibiotic resistance, virulence gene, and molecular profiles of Shiga toxin-producing Escherichia coli (STEC) non-O157 strains isolated from human stool samples, cow stool samples, and beef samples over a period of 2 years in Calcutta, India, were determined. Resistance to one or more antibiotics was observed in 49.2% of the STEC strains, with some of the strains exhibiting multidrug resistance. The dominant combinations of virulence genes present in the strains studied were stx1 and stx2 (44.5% of strains) and stx1, stx2, and hlyA (enterohemorrhagic E. coli hemolysin gene) (19% of strains). Only 6.4% of the STEC strains harbored eae. The diversity of STEC strains from various sources was assessed by random amplification of polymorphic DNA (RAPD). STEC strains that gave identical or nearly similar DNA fingerprints in RAPD-PCR and had similar virulence genotypes were further characterized by pulsed-field gel electrophoresis (PFGE). Identical RAPD and PFGE profiles were observed in four sets of strains, with each set comprising two strains. There was no match in the RAPD and PFGE profiles between strains of STEC isolated from cows and those isolated from humans. It appears that the clones present in bovine sources are not transmitted to humans in the Calcutta setting although these strains showed evolutionary relatedness. Maybe for this reason, STEC has still not become a major problem in India.

Solid dispersion of prednisolone: solid state characterization and improvement of dissolution profile

Background: Dissolution testing is an important test for judging the effectiveness of a pharmaceutical dosage form. Many drugs create adverse effect because of insufficient solubility at the physiological pH. This study is aimed to improve the dissolution properties of prednisolone (PRD) that falls under the category of class II biopharmaceutics system. Methods: In this study, preparation of solid dispersions with various water-soluble carriers was studied to improve the dissolution of PRD. To obtain the optimized formulation, solid dispersions were prepared employing different methods using different carriers with various drug:carrier ratios. Their dissolution behaviors were also compared. Fourier transform infrared (FTIR) spectroscopy, powder X-ray diffraction, and thermal analysis were studied to characterize the prepared solid dispersion. Results: PRD formed stable complexes with carriers as indicated by the stability constants (Ka) of 9.5–597.2 M−1. The results indicated that in vitro dissolution rate of PRD was remarkably improved in the solid dispersion of the drug compared with physical mixture and drug alone. This can be attributed to improved wettability, dispersibility, decrease in crystallinity, and increase in amorphous fraction of the drug. The results obtained from Fourier transform infrared spectroscopy and powrer X-ray diffraction showed good evidence of drug–carrier interaction while using carriers such as hydroxypropyl-β-cyclodextrin (HP-βCD) and polyethylene glycol (PEG). Crystallinity of the drug was reduced in the solid dispersions prepared with hydroxypropyl-β-cyclodextrin, polyvinylpyrrolidone-co-vinyl acetate 64, and PEG as revealed from the differential scanning calorimetry thermograms. Conclusion: The results suggested that the solid dispersion with selected excipients is a powerful tool to accelerate the dissolution of poorly water-soluble drugs.

Transdermal delivery of atenolol: effect of prodrugs and iontophoresis.

Inadequate skin permeability is the main challenge encountered in the transdermal drug delivery and to solve this crisis physical and chemical enhancement techniques are being developed. The aim of the present investigation was to study the combined effect of two such techniques, iontophoresis and esterification, on the transdermal delivery of atenolol. A series of ester prodrugs of atenolol were synthesized, characterized and studied for physicochemical properties and stability. In vitro permeation studies were carried out for atenolol and prodrugs at different donor concentrations (5, 10, and 20 mM) by passive process and iontophoresis (0.5 mA/cm(2)). Evaluation of the physicochemical parameters showed significant increase in lipophilicity and slight reduction in pK value in the ester prodrugs compared to parent drug. Stability studies revealed higher stability at pH 4 than pH 6. Prodrugs significantly enhanced the transdermal flux of atenolol in passive process while in iontophoresis the enhancement ranged from 1.4 to 2.7 fold compared to atenolol. In the prodrug series, permeation rate increased with increase in the length of alkyl side chain up to the addition of 5 carbon units, but thereafter no specific pattern was recorded in both passive and iontophoretic process. The steady state flux was highest in atenolol valerate (1.48 micromol/cm(2) h), which shows the promise of meeting the desired permeation rate (3.0- 31.0 micromol/ h) for maintenance of the therapeutic level in a 70 kg human.

Iodine nutritional status of children in North East India

ObjectiveTo assess the iodine nutritional status of school children in selected areas of Imphal West District of Manipur where endemic goitre and associated iodine deficiency disorders (IDD) are prevalent in the post-salt iodization period.MethodsA total of 961 school children in the age group 6–12 yrs of both sexes were clinically examined for goiter from three study areas-one from rural block and two from urban areas. One hundred twenty urine samples were, analysed for iodine and thiocyanate respectively. One hundred and five edible salt samples were also collected from the households to evaluate the iodine content. Drinking water samples from different sources were collected and iodine level was analysed to study the bioavailability of iodine in the region.ResultsThe total goiter rate was 34.96% (Grade 1–32.15%; Grade 2–2.81%) showing that IDD is a severe public health problem. The median urinary iodine levels in the studied areas were in the ranges from 12.5–17.5 μg/dl indicating no biochemical iodine deficiency in the region. Mean urinary thiocyanate level was 0.839±0.33 mg/dl showing that the people consume sufficient foods containing thiocyanate precursors. About 82% salt samples had iodine level more than 30 ppm and the iodine content in salt samples less than 15 ppm was only about 3% indicating the salt samples at house hold contain adequate iodine.ConclusionIodine content in drinking water samples ranged from 1.8–2.6 μg/l showing that the studied region is environmentally iodine deficient. Inspite of the consumption of adequate iodine, the existing goiter prevalence among school children during post salt iodization phase ensures that environmental factors other than iodine deficiency may have the possible role in the persistence of endemic goiter in the population. The role of thiocyanate in this regard may not be ruled out.

Protein Removal from Whey Waste by Foam Fractionation in a Batch Process

The work investigates the separation of proteins from whey waste collected from a local confectionery by the foam fractionation technique in batch mode. The purpose of this work was to evaluate performance criteria of protein separation. The effects of pH, the concentration of initial feed solution, the nitrogen flow rate, the % gas hold up, the bubble diameter, the breaking time of foam, and the optimization of the protein–surfactant ratio (1.5:1) were investigated in detail. Maximum enrichment ratio (48.189), %Rp (96.378) were observed at a gas flow rate of 330 ml/min and pH 5 that is closest to isoelectric point of observed proteins (Bovine serum albumin, β-Lactoglobulin, α-lactalbumin).

Synthesis and comparative skin permeability of atenolol and propranolol esters

The prodrug approach is one of the methods which have been evaluated for improving the systemic delivery of pharmacologically active compounds. ln the present study, we have synthesized ester prodrugs of atenolol and propranolol by adding alkyl side chains to the β-hydroxy function of the drug with the objective of enhancing their lipophilicity. In vitro skin permeability study in excised mice skin showed that the prodrugs permeate freely through the skin than the respective drug moieties and significant flux enhancement (6.2-fold) was observed in both cases. In the case of atenolol, the highest permeability coefficient was shown by capriate (C 10 side chain) where as in propranolol the highest permeability was recorded with caproate ester (C 6 side chain). The difference in permeability may be attributed to their difference in the intrinsic lipophilicities.

Recent trends in transdermal cardiovascular therapy

Transdermal dosage forms, though a costly alternative to the conventional formulations, are becoming popular because of some unique advantages. Controlled zero-order absorption, simple administration mode and the option of easy removal in case of adverse manifestations make them particularly desirable in cardiovascular therapy. Nitroglycerin and isosorbide dinitrate, the two antiischaemic drugs; and clonidine, an antihypertensive molecule, are being extensively used in the transdermal form. Studies that compared these patches with the established dosage forms had shown that though patches were costlier than conventional prescription products, they reduced the occurrence of hospitalization and diagnostic costs. Currently a number of antihypertensive drugs are being developed for transdermal administration. This article reviews the research on cardiovascular patches as well as the marketed products.

Modulation of drug (metoprolol succinate) release by inclusion of hydrophobic polymer in hydrophilic matrix

The objective of this study was to develop sustained release (SR) matrix tablets of metoprolol succinate (MS), by using different polymer combinations and fillers, to optimize by response surface methodology and to evaluate biopharmaceutical parameters of the optimized product. Matrix tablets of various combinations were prepared with cellulose-based polymers: hydroxy propyl methyl cellulose (HPMC) and ethyl cellulose (EC); and lactose and dibasic calcium phosphate dihydrate (DCP) as fillers. Study of pre-compression and post-compression parameters facilitated the screening of a formulation with best characteristics that underwent here optimization study by response surface methodology (Central Composite Design). The optimized tablet was subjected to further study like scanning electron microscopy, swelling study and in vivo study in rabbit model. Both in vitro and in vivo study revealed that combining of HPMC K100M (21.95%) with EC (8.85%), and use of DCP as filler sustained the action up to 12 h. The in vivo study of new SR tablets showed significant improvement in the oral bioavailability of MS in rabbits after a single oral dose of 25 mg. The delayed Tmax and lower Cmax indicated a slow and SR of MS from the optimized matrix tablets in comparison with the immediate release dosage form. The developed SR (MS) tablet of improved efficacy can perform therapeutically better than conventional tablet.

Design and evaluation of mucoadhesive beads of glipizide as a controlled release drug delivery system.

Abstract The present work aims at the development of a low-cost controlled release system of glipizide beads embedded in pectin to overcome the problem of frequent dosing of drug. The method of preparation has been optimised by experimental design to achieve satisfactory responses with respect to controlling variables. The controlling variables are X1, drug–polymer ratio; X2, surfactant concentration and X3, isooctane–acetone ratio. The most effective combination is X1(1:6), X2(1%), X3(50:50). Various parameters such as mucoadhesivity and swellability of beads, characterisation, dissolution, stability, ex vivo absorption and in vivo (Oral glucose tolerance test in rat) studies were performed with the optimised product. The optimised product was found quiet satisfactory that showed yield of 86.78%, drug entrapment efficiency (DEE) of 87.38% and drug release was extended up to 18 h. The present formulation of glipizide is a promising multiparticulate system of glipizide with significant hypoglycemic effect, and moreover it was prepared rapidly with ease.

Environmental isolates of Citrobacter braakii that agglutinate with Escherichia coli O157 antiserum but do not possess the genes responsible for the biosynthesis of O157 somatic antigen.

While searching for Escherichia coli O157 in the aquatic environment of Calcutta using an immunodetection procedure, we fortuitously detected five strains of Citrobacter braakii, which cross-reacted with the commercially available O157 polyvalent antiserum. The five C. braakii isolates gave positive results when a sensitive dot-ELISA was performed with E. coli O157 monoclonal antibody. Further, the O157 monoclonal antibody recognized the bands of proteinase K treated whole cells of lipopolysaccharide of all the C. braakii isolates. Apart from weak reactions with two or three of the DNA probes, all the C. braakii strains did not hybridize with the other probes spanning the minimum region required for O157 O-antigen biosynthesis. These strains did not possess any of the virulence genes that are commonly found in the Shiga toxin-producing E. coli (STEC) specially the serotype O157: H7. Therefore, it appears that the serological cross-reaction between C. braakii and E. coli O157 antiserum is based on structural mimicry between the O-polysaccharide of C. braakii and E. coli O157.