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Biomedical subjects

A Pandey

Publications and source records attributed to A Pandey.

At least 55 records · Page 3Linked to original sources
PubMed2000

Src-like adaptor protein (SLAP) is a negative regulator of T cell receptor signaling.

Initiation of T cell antigen receptor (TCR) signaling is dependent on Lck, a Src family kinase. The Src-like adaptor protein (SLAP) contains Src homology (SH)3 and SH2 domains, which are highly homologous to those of Lck and other Src family members. Because of the structural similarity between Lck and SLAP, we studied its potential role in TCR signaling. Here, we show that SLAP is expressed in T cells, and that when expressed in Jurkat T cells it can specifically inhibit TCR signaling leading to nuclear factor of activated T cells (NFAT)-, activator protein 1 (AP-1)-, and interleukin 2-dependent transcription. The SH3 and SH2 domains of SLAP are required for maximal attenuation of TCR signaling. This inhibitory activity can be bypassed by the combination of phorbol myristate acetate (PMA) and ionomycin, suggesting that SLAP acts proximally in the TCR signaling pathway. SLAP colocalizes with endosomes in Jurkat and in HeLa cells, and is insoluble in mild detergents. In stimulated Jurkat cells, SLAP associates with a molecular signaling complex containing CD3zeta, ZAP-70, SH2 domain-containing leukocyte protein of 76 kD (SLP-76), Vav, and possibly linker for activation of T cells (LAT). These results suggest that SLAP is a negative regulator of TCR signaling.

3T3 Cells↗
PubMed2000

Analysis of receptor signaling pathways by mass spectrometry: identification of vav-2 as a substrate of the epidermal and platelet-derived growth factor receptors.

Oligomerization of receptor protein tyrosine kinases such as the epidermal growth factor receptor (EGFR) by their cognate ligands leads to activation of the receptor. Transphosphorylation of the receptor subunits is followed by the recruitment of signaling molecules containing src homology 2 (SH2) or phosphotyrosine interaction domains (PID). Additionally, several cytoplasmic proteins that may or may not associate with the receptor undergo tyrosine phosphorylation. To identify several components of the EGFR signaling pathway in a single step, we have immunoprecipitated molecules that are tyrosine phosphorylated in response to EGF and analyzed them by one-dimensional gel electrophoresis followed by mass spectrometry. Combining matrix-assisted laser desorption/ionization (MALDI) and nanoelectrospray tandem mass spectrometry (MS/MS) led to the identification of nine signaling molecules, seven of which had previously been implicated in EGFR signaling. Several of these molecules were identified from low femtomole levels of protein loaded onto the gel. We identified Vav-2, a recently discovered guanosine nucleotide exchange factor that is expressed ubiquitously, as a substrate of the EGFR. We demonstrate that Vav-2 is phosphorylated on tyrosine residues in response to EGF and associates with the EGFR in vivo. Binding of Vav-2 to the EGFR is mediated by the SH2 domain of Vav-2. In keeping with its ubiquitous expression, Vav-2 seems to be a general signaling molecule, since it also associates with the platelet-derived growth factor (PDGF) receptor and undergoes tyrosine phosphorylation in fibroblasts upon PDGF stimulation. The strategy suggested here can be used for routine identification of downstream components of cell surface receptors in mammalian cells.

ErbB Receptors↗
PubMed2000

Solid state cultivation--an efficient method to use toxic agro-industrial residues.

Studies were carried out to screen twelve strains of Lentinus edodes for their efficiency to grow on toxic agro-industrial residues of coffee industry in solid state cultivation (SSC). Based on best mycelial growth (7.57 mm/day) and biomass production (48.78 mg/plate in 12 days at 24 degrees C) in coffee husk extract medium, a strain, L. edodes LPB 02 was selected for mushroom cultivation in SSC on coffee husk (treated and untreated), coffee spent ground, and a mixed-substrate comprising coffee husk and coffee spent ground (1:1). SSC was carried out under different conditions of moisture and spawn rate. Spawn rate of 10% and moisture level of 55-60% was found suitable for all the substrates. Treatment of the coffee husk with hot water was found useful for its utilization by the fungus. Results showed that there was an increase in the protein content and decrease in the fibre content of the substrates after SSC. Fruiting bodies were obtained from the treated coffee husk, spent ground and mixed-substrate, and the biological efficiency achieved was 85.8, 88.6 and 78.4% for these substrates, respectively. However, no fruiting body was obtained with raw coffee husk was used as the substrate. Results showed that after SSC, there was a decrease of about 27, 40 and 24% in caffeine and about 18, 49 and 12% in tannin contents in the treated coffee husk, coffee spent ground and mixed substrate, respectively. No caffeine or, tannins were found in fruiting body indicating their degradation by the fungal strain.

Biodegradation, Environmental↗
PubMed2000

Cloning of a receptor subunit required for signaling by thymic stromal lymphopoietin.

Signaling by type I cytokines involves the formation of receptor homodimers, heterodimers or higher order receptor oligomers. Here we report the cloning of a type I cytokine receptor subunit that is most closely related to the common cytokine receptor gamma chain (gamma c). Binding and crosslinking experiments demonstrate that this protein is the receptor for a recently described interleukin 7 (IL-7)-like factor, thymic stromal lymphopoietin (TSLP). Binding of TSLP to the thymic stromal lymphopoietin receptor (TSLPR) is increased markedly in the presence of the IL-7 receptor alpha chain (IL-7R alpha). IL-7R alpha-expressing but not parental 32D cells proliferate in the presence of exogenous TSLP. Moreover, a combination of IL-7R alpha and TSLPR is required for TSLP-dependent activation of a STAT5-dependent reporter construct. Thus it is shown that IL-7R alpha is a component of both the IL-7 and TSLP receptors, which helps to explain why deletion of the gene that encodes IL-7R alpha affects the lymphoid system more severely than deletion of the gene encoding IL-7 does. Cloning of TSLPR should facilitate an understanding of TSLP function and its signaling mechanism.

Amino Acid Sequence↗
PubMed2000

Advances in microbial amylases.

This review makes a comprehensive survey of microbial amylases, i.e. alpha-amylase, beta-amylase and glucoamylase. Amylases are among the most important enzymes and are of great significance in present-day biotechnology. Although they can be derived from several sources, such as plants, animals and micro-organisms, the enzymes from microbial sources generally meet industrial demands. Microbial amylases could be potentially useful in the pharmaceutical and fine-chemical industries if enzymes with suitable properties could be prepared. With the advent of new frontiers in biotechnology, the spectrum of amylase application has widened in many other fields, such as clinical, medicinal and analytical chemistries, as well as their widespread application in starch saccharification and in the textile, food, brewing and distilling industries. In this review, after a brief description of the sources of amylases, we discuss the molecular biology of amylases, describing structures, cloning, sequences, and protoplast fusion and mutagenesis. This is followed by sections on their production and finally the properties of various amylases.

Amylases↗
PubMed2000

Lutzomyia whitmani (Diptera: Psychodidae) as vector of Leishmania (V.) braziliensis in Paraná state, southern Brazil.

The phlebotomine sandflies in the northern areas of the state of Paraná, Brazil, particularly those in the '16a' health region, were investigated over a 3-year period. Using CDC light traps (with and without hamster bait) and Shannon traps (with lights and horse or human bait), 16 species were collected from seven municipal districts which were known foci for cutaneous leishmaniasis: Arapongas; Apucarana; Cambira; Marumbi; Faxinal; Florestópolis; and Sabáudia. Although the frequency at which each species was collected varied with the collection site, Lutzomyia whitmani predominated (62.0% of all the sandflies collected), followed by Lu. fischeri (13.3%), Lu. pessoai (10.8%), Lu. migonei (8.2%) and Lu. intermedia (2.8%). Lutzomyia monticola, Lu. shanonni, Lu. firmatoi, Lu. lanei, Lu. alphabetica, Lu. misionensis, Lu. correalimai, Lu. cortellezzii, Lu. longipenis, Brumptomyia brumpti and B. nitzulescui together represented the remaining 3.0% of the collected sandflies. Three of the 1961 female sandflies collected and dissected in the municipal district of Cambira, where a recent case of cutaneous leishmaniasis had been registered, were found to have flagellates in their guts. All three were Lu. whitmani. The parasites from each of these infections were successfully isolated in NNN and 'Tobie and Evans' media and/or by inoculation into a hind foot of a golden hamster. The results of isoenzyme electrophoresis indicated that all three isolates were of Leishmania (Viannia) braziliensis.

Animals↗
PubMed2000

Prevalence of MLR blocking antibodies before and after immunotherapy.

Immunologically specific blocking factors (BF) are believed to play a protective role in the maintenance of pregnancy. We compared the levels of BF in normal pregnant women and in patients with recurrent spontaneous abortion (RSA) and observed that the two groups differ significantly from one another. MLC inhibitory activity was present throughout normal pregnancy and was found to be specific to the husband's HLA antigens. Immunotherapy was performed in 28 recurrent aborters using husband's lymphocytes, after which levels of blocking antibodies increased in 23 patients. The difference in the label of MLR BF in the preimmunotherapy and postimmunotherapy groups was statistically significant and was associated with successful pregnancy outcome in 82.15% of cases. The appearance of the MLR BF and its continuation in a successful pregnancy might represent an appropriate immune state that may be playing an important role in maintenance of pregnancy.

Abortion, Habitual↗
PubMed2000

Acute respiratory tract infections in Indian children with special reference to Mycoplasma pneumoniae.

A total of 70 Indian children of either sex and under 5 years of age who were admitted to the All India Institute of Medical Sciences, New Delhi during a 1-year period (January 1994-December 1994) with complaints suggestive of acute respiratory tract infections (ARTI), were investigated for bacterial aetiology of infection with special reference to Mycoplasma pneumoniae. Microbial aetiology could be established in 44/70 (62.8 per cent) of cases of ARTI. Mycoplasma pneumoniae infection was seen in 21/70 (30 per cent), aerobic bacteria in 14/70 (20 per cent), Chlamydia pneumoniae in 2/70 (2.8 per cent), and mixed infection with mycoplasma either with bacteria and/or chlamydia in 7/70 (10 per cent). However, in 26/70 (37.1 per cent) cases no cause could be detected. Diagnosis of infection with M.pneumoniae was based on culture in 2/20 (10 per cent) cases, antigen detection in throat swab by indirect immunofluorescence assay using specific antibody in 16/70 (22.8 per cent) cases, and demonstration of IgM antibody in serum by serodia Myco II particle agglutination test in 17/70 (24.2 per cent). Streptococcus pneumoniae (9/70, 12.8 per cent) and Staphylococcus aureus (5/70, 7.1 per cent) were the aerobic isolates from blood in these patients. Results of this study indicate that M.pneumoniae plays a significant role in respiratory tract infection in an Indian paediatric population. Rapid diagnostic procedures, such as antigen detection and IgM antibody demonstration, should be used more widely to determine the infective aetiology early in the course of illness. The study also highlights the mixed aetiology in ARTI in children, which has important therapeutic implications.

Antibodies, Bacterial↗
PubMed1999

Production and shelf-life studies of low cost beverage with soymilk, buffalo cheese whey and cow milk fermented by mixed cultures of Lactobacillus casei ssp. shirota and Bifidobacterium adolescentis.

A study was performed to develop a fermented milk beverage with the aim to increase the potential application of buffalo cheese whey and soymilk. A mixed substrate was prepared by selective combination, which contained buffalo cheese whey 35%, soymilk 30% and cow milk 35%. The substrate mixture was fermented by a mixed culture of Lactobacillus casei shirota and Bifidobacterium adolescentis at 37 degrees C for 8 h keeping a 1:1.5 proportion between the lactic and bifidobacteria within a 5% (v/v) inoculum size. The fermented beverage was lightly extra-flavoured with vanilla essence and subjected to chemical, microbiological and sensory evaluations during storage for 28 days at 4 degrees C. Except a slight variation in the acidity, no other properties changed even after 28 days. There were no contaminating organisms (Salmonella and coliforms), which indicated the sanitary and hygienic conditions of the processing and the viable cells of the bacterial strains was well within recommended limits (6.8 x 10(8) cells for L. casei and 2.3 x 10(7) cells for Bifidobacterium). No negative changes were found in the sensory characteristics of the beverage allowing its good acceptability in all during the storage period.

Animals↗
PubMed1999

Nucleotide sequence databases: a gold mine for biologists.

The rapid expansion of nucleotide sequence data available in public databases is revolutionizing biomedical research. These databases have a variety of uses, including the discovery of novel genes, identification of homologous genes, analysis of alternative splicing, chromosomal localization of genes, and detection of polymorphisms. Data sets such as the human transcript map will undoubtedly accelerate identification of candidate genes in positional-cloning approaches. Careful in silico analysis can significantly reduce the amount of lab work required. Approximately half of all human genes are represented in these databases; therefore, one need not wait for the entire human genome to be sequenced before performing genome-wide studies.

Base Sequence↗
PubMed1999

Adolescent transition to coitus and premarital childbearing in Sudan: a biosocial context.

This paper examines the biosocial basis of premarital sexual and reproductive behaviour among women in Sudan. It applies Udry's biosocial perspective, which attempts to reconcile the biological and sociological models of premarital sexual and reproductive behaviour. World Fertility Survey (WFS) data were used to study premarital first motherhood. Early puberty was found to be paramount in determining childbearing in a separate biological model, but also in a biosocial model constructed to take account of social controls. This finding suggests that social controls do not influence the biological predisposition to premarital sexual behaviour. However, given the limitations of the WFS data, conclusive evidence must await a more appropriately designed study of reproductive behaviour in Sudan.

Adolescent↗
PubMed1999

Recent developments in microbial inulinases. Its production, properties, and industrial applications.

Microbial inulinases are an important class of industrial enzymes that have gained much attention recently. Inulinases can be produced by a host of microorganisms, including fungi, yeast, and bacteria. Among them, however, Aspergillus sp. (filamentous fungus) and Kluyveromyces sp. (diploid yeast) are apparently the preferred choices for commercial applications. Among various substrates (carbon source) employed for their production, inulin-containing plant materials offer advantages in comparison to pure substrates. Although submerged fermentation has been universally used as the technique of fermentation, attempts are being made to develop solid-state fermentation technology also. Inulinases catalyze the hydrolysis of inulin to D-fructose (fructose syrup), which has gained an important place in human diets today. In addition, inulinases are finding other newer applications. This article reviews more recent developments, especially those made in the past decade, on microbial inulinases--its production using various microorganisms and substrates. It also describes the characteristics of various forms of inulinases produced as well as their applications.

Aspergillus↗
PubMed1999

The realm of microbial lipases in biotechnology.

In this review, a comprehensive and illustrious survey is made of the applied aspects of microbial lipases in modern biotechnological practices. Lipases are the most versatile biocatalyst and bring about a range of bioconversion reactions such as hydrolysis, interesterification, esterification, alcoholysis, acidolysis and aminolysis. After a brief description of the microbial sources of lipases, the pivotal role of lipases in the processes and products of the food and flavourings industry is illustrated. An illustration is presented of biomedical applications. The panorama of lipases in the manufacture of fine chemicals is depicted with special emphasis on pharmaceuticals, pesticides, cosmetics, biosensors and detergents. Widening applications such as those in waste management and improved tanning techniques are other novel aspects of lipase utilization that are discussed in this review.

Bacteria↗
PubMed1999

Oral-facial-digital syndrome with acromelic short stature: a new variant--overlap with Ellis Van Creveld syndrome.

The Oral-Facial-Digital syndromes (OFDS) are a heterogeneous group of disorders having common oral, facial, and digital malformations. Here, we report a consanguineous family with a new variety of OFDS associated with acromelic short stature and genu valgum; the features overlapping with Ellis Van Creveld syndrome. One of the sibs has urinary incontinence and growth hormone deficiency, which has not been reported earlier in any type of OFDS in the literature.

Body Height↗
PubMed1999

Evaluation of p-nitrophenyl substituted semicarbazones for anticonvulsant properties.

A series of p-nitrophenyl substituted semicarbazones has been synthesised and their anticonvulsant activity was screened against MES, scPTZ and scSTY. 4(4'-Nitrophenyl)-o-nitrobenzaldehyde semicarbazone has been found to be the most active in all these tests. The studies revealed that a primary amino function is not essential for anticonvulsant activity in the semicarbazone series of compounds. Presumably these compounds could further act on glycine receptors.

Animals↗