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P Das

Publications and source records attributed to P Das.

At least 19 recordsLinked to original sources
PubMed1995

Isolation, cultivation and partial characterization of a kinetoplastid flagellate from the hindgut of the water bug, Lethocerus indicus.

A new species of kinetoplastid flagellates was isolated from the hindgut of the giant water bug, Lethocerus indicus, and successfully cultured in modified glycerol beef extract medium. Light and electron microscopic studies as well as growth in various culture media are described. The flagellates were in three different shapes and sizes in the hindgut of the host as well as in the culture medium. Each form of the parasite contained a kinetoplast which was located near the basal body of the flagellate. The ultrastructural features of this species exhibit great similarity to other species of Bodo. The flagellate ingested bacteria, grew in culture, and was identical with that observed in the hindgut of the bugs. The name Bodo indica has been proposed for this kinetoplastid flagellate.

Animals↗
PubMed1994

Monoclonal antibodies reactive with specific amino acid sequences of the 126 K protein of tobacco mosaic virus.

The 126 K protein of tobacco mosaic virus (TMV) is an NTP binding protein that has guanylyl transferase activity and is predicted to be an ATPase/helicase. In this paper we report the generation of monoclonal antibodies (Mabs) that react with specific amino acid sequences of the 126K protein. The Mabs were generated after immunizing mice with a partially purified preparation of the 126 K protein (native) obtained by centrifugal fractionation of the infected tissue extracts. The Mabs were assayed for specific reactivity by western blotting and by their reactivity with non-overlapping decapeptides corresponding to the entire amino acid sequence of the 126 K protein of TMV. A total of 11 Mabs reactive with specific peptides and three other Mabs that did not react with any peptide but reacted with the 126 K protein were identified.

Amino Acid Sequence↗
PubMed1992

Production of catecholamines in the human epidermis.

Cell-free extracts from human full thickness skin (i.e., epidermis and dermis), suction blister roofs (i.e., epidermis) and from human keratinocytes express biopterin-dependent tyrosine hydroxylase a well as phenylethanolamine-N-methyl transferase, both representing key enzymes for the biosynthesis of epinephrine. These enzyme activities could not be detected in cell extracts from human melanocytes and human fibroblasts. Since keratinocytes in the human epidermis, and in cell cultures, express a high density of beta-2-adrenoceptors, and this signal transduction system regulates intracellular calcium homeostasis, it can be concluded that epinephrine production in the epidermis activates calcium transport via the beta-2-adrenoceptor system. Our results show for the first time that the human epidermis has the capacity to independently produce epinephrine.

Biopterins↗
PubMed1992

Intracellular distribution of the 126K/183K and capsid proteins in cells infected by some tobamoviruses.

Leaves of plants infected by tobacco mosaic virus (TMV) strain U1, TMV strain M, tomato mosaic virus strain Dahlemense and tobacco mild green mosaic virus strain U2 were examined for the presence and intracellular distribution of their capsid and 126K/183K proteins by immunoblotting and immunogold electron microscopy. The bulk of the capsid protein was found in the virus bundles (crystals), although small amounts were found in the chloroplasts and nuclei of cells infected by some of these tobamoviruses. The 126K protein of TMV-U1 and -M was localized in the X-bodies, whereas in cells infected by the other two viruses which induce no X-bodies, the 126K protein was found to be associated with virus bundles.

Amino Acid Sequence↗
PubMed1992

Sch 42137, a novel antifungal antibiotic from an Actinoplanes sp. Fermentation, isolation, structure and biological properties.

A novel polycyclic xanthone, Sch 42137, related to the albofungin family of compounds was isolated from culture broth. Its structure was determined by detailed spectroscopic studies and comparison of circular dichroic studies to related compounds albofungin and simaomicin. Sch 42137 exhibited MIC values less than 0.125 micrograms/ml against yeasts and dermatophytes. Details are presented herein.

Actinomyces↗
PubMed1992

Detection of specific anti-Giardia antibodies in the serodiagnosis of symptomatic giardiasis.

The roles of circulating anti-Giardia IgM and IgG antibodies were assayed by the Enzyme linked immunosorbent assay (ELISA) using axenic Giardia lamblia whole trophozoites as antigen for routine serodiagnosis of Giardia infection. Detection of anti-Giardia IgM antibody was found to be useful in the early detection of symptomatic giardiasis, whereas IgG detection was not, since the latter could not discriminate between present infection and previous exposure. A mean optical density (OD) +/- 2 standard deviation (SD) value of 0.088 at 1:100 serum dilution was found optimal for the detection of anti-Giardia IgM antibodies as it completely separated out the acute Giardia cases from the Giardia-free controls. The same sera did not reveal any marked differences when tested for anti-Giardia IgG antibodies. Detection of IgM antibodies correlated with high sensitivity and specificity (96%) in an evaluation of a large number of sera collected from Giardia cases and controls.

Animals↗
PubMed1992

Electrophoretic mobility and immunoblot analysis of the outer membrane proteins of Aeromonas hydrophila, A. sobria and A. caviae.

The outer membrane profiles of three species of the genus Aeromonas were examined by means of SDS-PAGE and immunoblotting to identify species-specific polypeptides and antigens which could presumably be applied to differentiate Aeromonas spp. at the species or subspecies level. Profiles on an 11% discontinuous SDS-PAGE showed common band sharing at the 52 kD position. Species-specific bands for the three strains could also be detected. Immunoblots using heterologous LPS-adsorbed polyclonal antisera revealed demarcated common and uncommon antigens within the three species. Outer membrane preparations were immunoblotted against whole cell polyclonal antisera. The previously documented host pathogenicity of A. sobria correlated well with the immunoblots which showed antigenicity, especially due to the LPS, when compared with the other two species.

Aeromonas↗
PubMed1992

R-ELISA: repeated use of antigen-coated plates for ELISA and its application for testing of antibodies to HIV and other pathogens.

In this paper we report on the evaluation of several procedures that allow for the repeated use of an antigen-coated, enzyme-linked immunosorbent assay (ELISA) plate for enzyme immunoassay (EIA). We have shown that antigen-coated ELISA plates that were incubated once with an aqueous solution containing 8 M urea, 2% sodium dodecyl sulfate and 2% mercaptoethanol, after an EIA, can be reused again for EIA without loss of antigenic capacity. Thus, in this procedure, after an EIA, the ELISA plates were washed once with the above solution and then in a buffer containing 20 mM Tris-HCl, pH 7.5, 0.1% Tween 20 and 500 mM NaCl. This washing protocol was shown to remove the primary antibody, enzyme-conjugated secondary antibody and substrate without removing the antigen from the ELISA plate microwells. Thus, an antigen-coated ELISA plate previously used for an assay could be reused. We tested this repeat ELISA (R-ELISA) procedure on high antigen-binding ELISA plates coated with two different plant virus proteins, a synthetic peptide, the p25/24 gag and the gp120 proteins of the human immuno-deficiency virus, or the staphylococcus enterotoxin protein. In each case tested, the procedure allowed for the repeated use of the same antigen-coated plates for EIA of the respective antibodies. This procedure should prove to be particularly valuable for mass screening of samples tested for HIV and other disease-causing agents.

Amino Acid Sequence↗
PubMed1991

Mammalian sex chromosomes. III. Activity of pseudoautosomal steroid sulfatase enzyme during spermatogenesis in Mus musculus.

Parallel to the inactivation of the X chromosome in somatic cells of female, the male X in mammals is rendered inactive during spermatogenesis. Pseudoautosomal genes, those present on the X-Y meiotically pairable region of male, escape inactivation in female soma. It is suggested, but not demonstrated, that they may also be refractory to the inactivation signal in male germ cells. We have assayed activity of the enzyme steroid sulfatase, product of a pseudoautosomal gene, in testicular cells of the mouse and shown its presence in premeiotic, meiotic (pachytene), and postmeiotic (spermatid) cell types. It appears that, as in females, pseudoautosomal genes may escape inactivation in male germ cells also.

Animals↗
PubMed1991

Identification of heterogeneity in human isolates of Giardia lamblia by isoenzyme studies.

Electrophoretic mobility patterns of six enzymes, viz. alkaline phosphatase E.C. 3.1.3.1., acid phosphatase E.C. 3.1.3.2., malic enzyme E.C. 1.1.1.40., phosphoglucomutase E.C. 2.7.5.1., isocitrate dehydrogenase E.C. 1.1.1.42., glucose-6-phosphate dehydrogenase E.C. 1.1.1.49 of two axenically cultured human Giardia lamblia isolated from India (PD-1 and PD-2) and one strain from Portland, Oregon, USA (P-1) were compared using polyacrylamide gel electrophoresis (PAGE). Based on the difference in the mobility patterns of the enzymes phosphoglucomutase, isocitrate dehydrogenase and malic enzyme, the PD-1 and PD-2 isolates appeared to be quite different from P-1. In the present study, the isocitrate dehydrogenase and alkaline phosphatase enzymes were used for the first time for differentiation of Giardia isolates. In the case of PD-1, two alkaline phosphatase bands could be seen whereas only one band was observed in PD-2 and P-1. Thus, the three strains could be grouped into three different zymodemes. These findings reveal the significant heterogeneity in G. lamblia isolates both from widely separated areas and within a single region. Heterogeneity among G. lamblia strains may explain the variable clinical manifestations, host response and treatment efficacy characteristic of human giardiasis.

Acid Phosphatase↗
PubMed1991

Epidemiology of campylobacteriosis in a cohort of rural population near Calcutta.

Over a 2-year period, 25 families comprising of 181 individuals of all ages were longitudinally observed for the excretion of Campylobacter species. Faecal samples were taken from all persons with diarrhoea. Specimens were also taken from apparently healthy individuals and from domestic animals living within the confines of the study families at monthly intervals. The overall diarrhoea attack rate was 19 episodes per 100 person-years with peak incidence in the 1- to 4-year-old age group (76/100 person-years). Eight (11.5%) of the total episodes were campylobacter-associated and the overall rate of campylobacter positive diarrhoeal episodes were 2.2 per 100 person-years. Of the 1002 stool samples from healthy individuals 32 (3.2/100 samples) were positive for campylobacter. The organism was most frequently isolated from children under 1 year of age both during diarrhoeal episodes (11.5 per 100 person-years) and non-diarrhoeal (11.1 per 100 samples). Multiple infections in a family were rare. In 19.4% of the occasions one or more animals were campylobacter positive. However, only in 7.7% of these occasions was a human infection recorded within 1 month after the animal was found to be positive. The study showed that the epidemiology of campylobacteriosis in this community was distinct compared to that observed in developed countries.

Adolescent↗
PubMed1991

A temporal study of the expression of the capsid, cytoplasmic inclusion and nuclear inclusion proteins of tobacco etch potyvirus in infected plants.

Young leaves of tobacco, systemically infected by tobacco etch potyvirus (TEV), were examined for the presence and distribution of four virus encoded proteins [capsid, cytoplasmic inclusion (CI) and two nuclear inclusion (NI) proteins] at various time periods after inoculation of expanded leaves of the plants. The analyses were carried out by ELISA and by immunogold electron microscopy of thin sections of the leaves. All four proteins were detected simultaneously in the systemic leaves for the first time on the fifth day after inoculation of the expanded leaves. All four proteins increased in concentration until the seventh day and then showed no further increase with the exception of the capsid protein which continued to accumulate. The CI protein was first detected in association with the plasmalemma/cell wall and was subsequently found mostly in the form of pinwheels in the cytoplasm. The two NI proteins were found at all times after infection within the nucleus, although small concentrations were detected in the cytoplasm. These experiments suggest that both the NIa and NIb proteins are transported into the nucleus immediately after synthesis. At the earliest time periods after infection, high concentrations of these proteins (NIa and NIb) were found in their non-inclusion form in the nucleolus. At 14 days after infection, both proteins were found only as inclusions in the nucleus. The capsid protein was found at all stages of infection only in the cytoplasm.

Capsid↗
PubMed1991

Metacyclogenesis of Leishmania spp: species-specific in vitro transformation, complement resistance, and cell surface carbohydrate and protein profiles.

Metacyclic (stationary) and logarithmic (log) forms of promastigotes of Leishmania donovani and Leishmania major were characterized in several ways. The highly active metacyclic forms were larger with more protein and less carbohydrate. The flagellum increased in length 2.4 times in L. major as compared to 1.8 times in L. donovani. Resistance to complement-mediated lysis by normal human serum of in vitro grown Leishmania promastigotes was related to the species, the growth phase in culture, and also the temperature. Metacyclic forms of both species had a much increased resistance to killing by normal serum at different temperatures. Differences in membrane-exposed carbohydrates were detected by fluorescein-conjugated lectins. Peanut agglutinin and Ulex agglutinin I differentiated log and stationary phase promastigotes of L. major. Higher amounts of acid phosphatase were demonstrated in the metacyclic phase. Differences in polypeptides were detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Two polypeptides of approximately 51 and 114 kDa were found exclusively in metacyclic promastigotes of both species, whereas 38- and 23-kDa polypeptides were lost or reduced during transformation from log to metacyclic phase promastigotes of L. donovani. In addition, a 75-kDa polypeptide was expressed only in metacyclic promastigotes of L. major.

Acid Phosphatase↗
PubMed1990

Characterization of peptidyl-nucleoside antifungal antibiotics from fermentation broth.

Characterization of sinefungin related antifungal antibiotics from fermentation broth was accomplished by coupling photodiode array (PDA) detection to high performance liquid chromatography (HPLC). From the combined HPLC-PDA evaluation of broth filtrate, we detected five sinefungin related components. Fast atom bombardment (FAB) mass spectroscopic evaluations, mass-analysed ion kinetic energy spectra (MIKES) and collision activated (CA) MIKES of these components confirmed their respective identities. Our findings from the combination of HPLC photodiode array acquisition and FAB-mass spectrometry suggest we have detected the presence of a previously unreported sinefungin analogue.

Adenosine↗
PubMed1990

Potato virus Y helper component protein is associated with amorphous inclusions.

The distribution of the helper component (HC) protein of potato virus Y in tissues and cells of infected plants was studied by immunoblotting and immunogold labelling techniques. This HC protein was found in leaf blade and vein tissue but not in the petiole of leaves. In infected cells, the protein was localized in rod-shaped cytoplasmic inclusions known as amorphous inclusions.

Antibodies, Viral↗