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Biomedical subjects

A Pandey

Publications and source records attributed to A Pandey.

At least 19 recordsLinked to original sources
PubMed2003

Optical gain characteristics of C 460 and C 450.

Dye concentration dependent gain spectra for Coumarin 460 (C 460) and Coumarin 450 (C 450) in ethanol have been studied using Amplified Spontaneous Emission (ASE) technique under Nitrogen laser (337.1 nm) excitation in the concentration range 10(-2)-10(-5) m/l. The dependence of lasing wavelength and peak gain on concentration have been understood in terms of variation of fluorescence lifetime, which is due to photo-physical processes such as radiation trapping and concentration-quenching. Pump intensity dependence of efficiency is also explained in terms of fluorescence lifetime. A comparison of the stability of the two dyes has also been made on the basis of the functional groups at different positions of the basic coumarin.

Coumarins↗
PubMed2003

Optimization of phytase production by solid substrate fermentation.

The production of phytase by three feed-grade filamentous fungi ( Aspergillus ficuum NRRL 3135, Mucor racemosus NRRL 1994 and Rhizopus oligosporus NRRL 5905) on four commonly used natural feed ingredients (canola meal, cracked corn, soybean meal, wheat bran) was studied in solid substrate fermentation (SSF). A. ficuum NRRL 3135 had the highest yield [15 IU phytase activity/g dry matter (DM)] on wheat bran. By optimizing the supplementation of wheat bran with starch and (NH(4))(2)SO(4), phytase production increased to 25 IU/g DM. Optimization was carried out by Plackett-Burman and central composite experimental designs. Using optimized medium, phytase, phosphatase, alpha-amylase and xylanase production by A. ficuum NRRL 3135 was studied in Erlenmeyer flask and tray SSF. By scaling up SSF from flasks to stationary trays, activities of 20 IU phytase activity/g DM were reproducibly obtained.

6-Phytase↗
PubMed2003

Use of telemedicine in evading cholera outbreak in Mahakumbh Mela, Prayag, UP, India: an encouraging experience.

Telemedicine (TM) services a process in which expert medical advice from afar is provided using electronic signals to transfer the medical data from one site to another. As a pilot project to assess the efficacy of TM in developing countries like India, a telemedicine center was set up at the main hospital of Mahakumbh mela--a grand religious fair, at Prayag, a city in north India. The daily reporting of the in-patient and outpatient cases at the fair revealed a surge of diarrhea cases among the pilgrims at the fair. This information was communicated to the referral center at Sanjay Gandhi Post Graduate Institute of Medical Sciences (SGPGIMS), which, with the help of its microbiology department, conducted microbiological examinations of stool samples and rectal swabs of patients along with various water samples. Vibrio cholerae was isolated in 22.6% (7/31) of the samples. This information was immediately relayed to the Main Hospital at the fair online, and then to the health authorities, who took strict and prompt measures to improve hygiene. Subsequently, the number of diarrhea cases decreased considerably in a matter of a few days, and thus an epidemic disaster was averted, which could have created havoc in such a large gathering.

Aged↗
PubMed2002

A localised outbreak of Vibrio cholerae O139 in Kolkata, West Bengal.

BACKGROUND & OBJECTIVES: An explosive outbreak of diarrhoeal disease which occurred in the Baishnabghata, Patuli area of Kolkata Municipal Corporation during September 28 to October 12, 2000, was investigated by a team from the National Institute of Cholera and Enteric Diseases, Kolkata, to identify the causative agent and determine the antimicrobial susceptibility pattern. METHODS: Clinical and epidemiological data were collected from domiciliary cases and also from patients attending two medical camps that had been set up for the purpose. Stool and water samples were collected for isolation of diarrhoeagenic pathogens. RESULTS: A total of 710 cases of diarrhoea occurred with an attack rate of 7.1 per cent; majority were adults. All 6 faecal samples and 2 water samples collected, were positive for Vibrio cholerae O139. The strains were uniformly (100%) susceptible to the commonly used drugs for cholera such as tetracycline, norfloxacin, ciprofloxacin, co-trimoxazole and nalidixic acid but resistant (100%) to furazolidone and ampicillin. INTERPRETATION & CONCLUSION: This is the first localised outbreak of V. cholerae O139 in Kolkata since the devastating epidemic in 1992. Extensive chlorination of all water sources resulted in a dramatic decline of the outbreak. The appearance of resistance in V. cholerae O139 to furazolidone is a matter of great concern since this drug is used for the treatment of cholera in children and pregnant women.

Cholera↗
PubMed2001

Detection of tyrosine phosphorylated peptides by precursor ion scanning quadrupole TOF mass spectrometry in positive ion mode.

Phosphorylation is a common form of protein modification. To understand its biological role, the site of phosphorylation has to be determined. Generally, only limited amounts of phosphorylated proteins are present in a cell, thus demanding highly sensitive procedures for phosphorylation site determination. Here, a novel method is introduced which enables the localization of tyrosine phosphorylation in gel-separated proteins in the femtomol range. The method utilizes the immonium ion of phosphotyrosine at m/z 216.043 for positive ion mode precursor ion scanning combined with the recently introduced Q2-pulsing function on quadrupole TOF mass spectrometers. The high resolving power of the quadrupole TOF instrument enables the selective detection of phosphotyrosine immonium ions without interference from other peptide fragments of the same nominal mass. Performing precursor ion scans in the positive ion mode facilitates sequencing, because there is a no need for polarity switching or changing pH of the spraying solvent. Similar limits of detection were obtained in this approach when compared to triple-quadrupole mass spectrometers but with significantly better selectivity, owing to the high accuracy of the fragment ion selection. Synthetic phosphopeptides could be detected at 1 fmol/microL, and 100 fmol of a tyrosine phosphorylated protein in gel was sufficient for the detection of the phosphorylated peptide in the unseparated digestion mixture and for unambiguous phosphorylation site determination. The new method can be applied to unknown protein samples, because the identification and localization of the modification is performed on the same sample.

Amino Acid Sequence↗
PubMed2001

Characterization of promoter region and genomic structure of the murine and human genes encoding Src like adapter protein.

Src-like adapter protein (SLAP) was identified as a signaling molecule in a yeast two-hybrid system using the cytoplasmic domain of EphA2, a receptor protein tyrosine kinase (Pandey et al., 1995. Characterization of a novel Src-like adapter protein that associates with the Eck receptor tyrosine kinase. J. Biol. Chem. 270, 19201-19204). It is very similar to members of the Src family of cytoplasmic tyrosine kinases in that it contains very homologous SH3 and SH2 domains (Abram and Courtneidge, 2000. Src family tyrosine kinases and growth factor signaling. Exp. Cell. Res. 254, 1-13.). However, instead of a kinase domain at the C-terminus, it contains a unique C-terminal region. In order to exclude the possibility that an alternative form exists, we have isolated genomic clones containing the murine Slap gene as well as the human SLA gene. The coding regions of murine Slap and human SLA genes contain seven exons and six introns. Absence of any kinase domain in the genomic region confirm its designation as an adapter protein. Additionally, we have cloned and sequenced approximately 2.6 kb of the region 5' to the initiator methionine of the murine Slap gene. When subcloned upstream of a luciferase gene, this fragment increased the transcriptional activity about 6-fold in a human Jurkat T cell line and approximately 52-fold in a murine T cell line indicating that this region contains promoter elements that dictate SLAP expression. We have also cloned the promoter region of the human SLA gene. Since SLAP is transcriptionally regulated by retinoic acid and by activation of B cells, the cloning of its promoter region will permit a detailed analysis of the elements required for its transcriptional regulation.

Adaptor Proteins, Signal Transducing↗
PubMed2001

A reassessment of the translation initiation codon in vertebrates.

More than two decades ago Marilyn Kozak proposed the scanning model of translation initiation, whereby translation is initiated at the first AUG codon that is in a particular context. In this article, we re-examine the context of initiator codons using a large dataset of curated human transcripts. We find that more than 40% of transcripts contain AUG codons upstream of the actual start codon and that most authentic AUGs contain three or more mismatches from the consensus sequence, CCACCaugG. Also, in a large fraction of transcripts, the sequences surrounding the initiator codon deviate more from the consensus than those surrounding upstream AUGs, indicating that translation initiation from downstream AUGs is more common than generally believed.

5' Untranslated Regions↗
PubMed2001

Production, purification and properties of microbial phytases.

Phytases (myo-inositol hexakisphosphate phosphohydrolase, EC 3.1.3.8) catalyse the release of phosphate from phytate (mycoinositol hexakiphosphate). Several cereal grains, legumes and oilseeds, etc., store phosphorus as phytate. Environmental pollution due to the high-phosphate manure, resulting in the accumulation of P at various locations has raised serious concerns. Phytases appear of significant value in effectively controlling P pollution. They can be produced from a host of sources including plants, animals and micro-organisms. Microbial sources, however, are promising for their commercial exploitations. Strains of Aspergillus sp., chiefly A. ficuum and A. niger have most commonly been employed for industrial purposes. Phytases are considered as a monomeric protein, generally possessing a molecular weight between 40 and 100 kDa. They show broad substrate specificity and have generally pH and temperature optima around 4.5-6.0 and 45-60 degrees C. The crystal structure of phytase has been determined at 2.5 A resolution. Immobilization of phytase has been found to enhance its thermostability. This article reviews recent trends on the production, purification and properties of microbial phytases.

6-Phytase↗
PubMed2001

GPMAW--a software tool for analyzing proteins and peptides.

General Protein/Mass Analysis for Windows (GPMAW) is a valuable piece of software for any molecular biologist, biochemist or mass spectrometrist wishing to analyze protein or peptide sequences. All steps from the acquisition of protein sequence from a built-in web interface, to proteolytic digests, theoretical peptide fragmentation, detailed annotation of sequences and secondary structure prediction, can be performed rapidly and intuitively without first having to spend days reading manuals.

Amino Acid Sequence↗
PubMed2001

An evaluation of the use of two-dimensional gel electrophoresis in proteomics.

With whole genomes being sequenced almost routinely, the next logical step towards a better understanding of cellular mechanisms lies in studying the functional units of gene expression-proteins. One of the fundamental approaches in proteomics is the use of two-dimensional gel electrophoresis as a mode of separation and visualization of complex protein mixtures. Despite several limitations of the method, its ability to separate large numbers of proteins, including their post-translationally modified forms, ensures that it will continue to be popular in several well-defined areas of proteomics. In this article, we discuss the merits and drawbacks of two-dimensional gels and compare them with alternative systems such as one-dimensional gels and liquid chromatography-based separation methods. In the wake of recent advances in mass spectrometry and related areas, we outline areas where two-dimensional gels can best be utilized as the preferred separation method in proteomic strategies.

Electrophoresis, Gel, Two-Dimensional↗