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Biomedical subjects

A Datta

Publications and source records attributed to A Datta.

At least 127 records · Page 7Linked to original sources
PubMed1990

Non-organ specific & organ specific antibodies in rheumatoid arthritis.

Fifty patients of rheumatoid arthritis clinically diagnosed (by ARA criteria) were studied for both non-organ specific [rheumatoid factor (RF), anti-nuclear antibodies (ANA), extractable nuclear antibody (ENA), granulocyte specific anti-nuclear antibody (GS-ANA), anti-smooth muscle antibody (SMA) and anti-mitochondrial antibody (AMA)] and organ specific, [anti-adrenal (AAA), anti-islet cell (ICA), antithyroid antibody (ATA) and anti-parietal cell (PCA)] auto antibodies. RF was positive in 80 per cent of patients. ANA was positive in 44 per cent of patients, ENA in 62 per cent, SMA in 20 per cent, AMA in 18 per cent and GS-ANA in 68 per cent. Of the organ specific antibodies, PCA was demonstrable in 28 per cent of the patients and none of the other antibodies were present. Circumstantial evidence indicates that ANA and GS-ANA are not synonymous but independent, cross-reacting entities and the presence of both increase the sensitivity (94%) of diagnosis of RA.

Adolescent↗
PubMed1990

Isolation, partial purification and pharmacodynamics of a slow contractile substance in the venom sac extract of the wasp Vespa cincta Fabr.

The venom of V. cincta contains acetylcholine (ACh), histamine and 5-hydroxytryptamine (5-HT). Blockers of these agonists did not block completely the hypotensive and smooth muscle contractile activity of venom. On smooth muscle, there was a residual slow contraction. The active substance which produced this slow contraction was separated by solvent extraction, gel filtration and TLC. The purified material (which has been provisionally designated "Vecikinin") lowered cat, rat and guinea pig blood pressure, increased amplitude of cardiac contraction, and increased capillary permeability. Vecikinin contracted several smooth muscle preparations (rat uterus, rat ascending colon, guinea pig ileum, guinea pig colon and rat ileum), while relaxing rat duodenum. Its contractile activity was not lost on boiling, but acid or alkali-boiling reduced its contractile activity. It was inactivated on incubation with chymotrypsin and carboxypeptidase but not with trypsin, pepsin or leucine aminopeptidase. It is a peptide, appears to be of low molecular weight, and could be distinguished from substance P, angiotensin, bradykinin and hornet or wasp kinin.

Animals↗
PubMed1989

2-Acetylthiamin pyrophosphate (acetyl-TPP) pH-rate profile for hydrolysis of acetyl-TPP and isolation of acetyl-TPP as a transient species in pyruvate dehydrogenase catalyzed reactions.

Rate constants for the hydrolysis of acetyl-TPP were measured between pH values of 2.5 and 7.5 and plotted as log kobs versus pH. The pH-rate profile defined two legs, each with a slope of +1 but separated by a region of decreased slope between pH 4 and pH 6. The rates were insensitive to buffer concentrations. Each leg of the profile reflected specific-base-catalyzed hydrolysis of acetyl-TPP, analogous to the hydrolysis of 2-acetyl-3,4-dimethylthiazolium ion [Lienhard, G.E. (1966) J. Am. Chem. Soc. 88, 5642-5649]. The separation of the two legs of this profile has been shown to be caused by the ionization of a group exhibiting a pKa of 4.73 within acetyl-TPP that is remote from the acetyl group, the amino-pyrimidine ring, which is protonated below pH 4.73. The protonation level of this ring has been shown to control the equilibrium partitioning of acetyl-TPP among its carbinolamine, keto, and hydrate forms. The differential partitioning of these species is a major factor causing the separation between the two legs of the pH-rate profile. The characteristic pH-rate profile and the availability of synthetic acetyl-TPP [Gruys, K.J., Halkides, C.J., & Frey, P.A. (1987) Biochemistry 26, 7575-7585] have facilitated the isolation and identification of [1-14C]acetyl-TPP from acid-quenched enzymatic reaction mixtures at steady states. [1-14C]Acetyl-TPP was identified as a transient species in reactions catalyzed by the PDH complex or the pyruvate dehydrogenase component of the complex (E1). The pH-rate profile for hydrolysis of [1-14C]-acetyl-TPP isolated from enzymatic reactions was found to be indistinguishable from that for authentic acetyl-TPP, which constituted positive identification of the 14C-labeled enzymic species.

Hydrogen-Ion Concentration↗
PubMed1989

Current trends in Candida albicans research.

Candida albicans is an opportunistic pathogen of human beings and other mammals. Two other features, besides its pathogenicity, have made it a popular organism of study. It exists in different cellular forms and can change from one form to another, depending on growth conditions. Thus, it is being used as a model system to study cellular differentiation. It can also heritably and reversibly switch its cellular and colony morphologies. The yeast is diploid and lacks a sexual cycle. Thus, it has not been possible to apply the powerful methods of genetic analysis to understand morphogenesis or pathogenesis. Few clinical isolates are haploid, but they do not form hyphae and are not yet well characterized. Recombinant DNA techniques are increasingly being applied to C. albicans to solve many of the unanswered questions of morphogenesis and pathogenesis. Genetic transformation and gene-disruption techniques were recently developed for the yeast. Thus it is possible to study the role of any cloned gene through directed mutagenesis. However, the difficulty is to clone the putative genes involved in morphogenesis or pathogenesis. Candida albicans exists in four different cellular forms, namely blastospores, pseudohyphae, hyphae and chlamydospores. Blastospore-to-hypha conversion is well studied. A variety of conditions can induce this transition. It is not clear how cells sense such varied conditions and respond appropriately. In other systems where differentiation is well understood, regulatory genes which control differentiation have been uncovered. These genes cause differential expression of other genes, and ultimately differentiated phenotypes. Thus, it is likely that differential gene expression is involved in the bud-to-hypha transition in C. albicans. Certain proteins are expressed exclusively on the cell surface of hyphae. It should be possible to clone genes coding for these proteins. A study of the expression of these genes might allow us to identify the regulatory gene which determines differentiation. Another approach to understanding morphogenesis is to study how the difference in the shape of buds and hyphae is generated. This difference appears to be due to the differential activity of apical and general growth zones, which determine growth of the cell wall. Activity of these growth zones is apparently determined by actin localization. It remains a possibility that conditions which induce hyphae formation may directly affect actin localization or cell-wall growth zones and cause differences in cell shape. Candida albicans can also heritably switch its cellular phenotype. This has come to light from a study of colony-morphology switching. Some strains can switch their colony morphology, both heritably and reversibly.(ABSTRACT TRUNCATED AT 400 WORDS)

Candida albicans↗
PubMed1989

The Agrobacterium tumefaciens virC1 gene product binds to overdrive, a T-DNA transfer enhancer.

In Agrobacterium tumefaciens, a cis-active 24-base-pair sequence adjacent to the right border of the T-DNA, called overdrive, stimulates tumor formation by increasing the level of T-DNA processing. Recent results from our laboratory have suggested that the virC operon which enhances T-DNA processing probably does so because the VirC1 protein interacts with overdrive (N. Toro, A. Datta, M. Yanofsky, and E. W. Nester, Proc. Natl. Acad. Sci. USA 85:8558-8562, 1988). We report here the purification of the VirC1 protein from cells of Escherichia coli harboring a plasmid containing the coding sequences of the virC locus of the octopine Ti plasmid. By gel mobility shift and DNase I footprinting assays, we showed that this purified virC1 gene product binds to overdrive but not to the right border of T-DNA.

Bacterial Proteins↗
PubMed1989

Factors affecting the colonization of isolated rabbit intestinal epithelial cells by Vibrio cholerae 01 in vitro.

The adhesive capability of Vibrio cholerae 01 strains to isolated rabbit intestinal epithelial cells was maximally expressed when the bacteria were grown in synthetic broth and was enhanced by the presence of Ca2+ in the growth media. N-Acetyl-D-glucosamine could inhibit the adhesion of the bacteria to rabbit intestinal epithelial cells as could lipopolysaccharide O-antigen from Vibrio cholerae 01 and lectin from Triticum vulgaris. Since the lipopolysaccharide is known to contain N-acetyl-D-glucosamine and because the lectin from Triticum vulgaris shows specificity for this sugar, it is probable that N-acetyl-D-glucosamine is actively involved in the adhesion of Vibrio cholerae 01 to isolated rabbit intestinal epithelial cells.

Animals↗
PubMed1988

Characterization of the virB operon from an Agrobacterium tumefaciens Ti plasmid.

The virulence genes of the Agrobacterium tumefaciens Ti plasmid are grouped into six transcription units and direct the transfer of T-DNA into plant cells. We report here the nucleotide sequence of the largest vir operon, virB, from the Ti plasmid pTiA6NC. This operon contains 11 open reading frames, 7 of which show evidence of translational coupling. trpE::virB gene fusions were used to confirm the reading frames of genes virB2, 4, 5, 6, 7, 8, 10, and 11. In addition, the native gene products of virB6 and virB9 were identified using maxicell and in vitro transcription-translation techniques, and the VirB9 protein was found to be proteolytically processed. The codon usage of the predicted virB genes is very similar to the other pTiA6 vir genes and is much less biased than Escherichia coli. Since many of the virB gene products have secretion signals common to exported bacterial proteins, it is likely that they will be membrane-associated. We propose that the VirB proteins are involved in the formation of a transmembrane structure which mediates the passage of the transferred T-DNA molecule through the bacterial and plant cell membranes.

Base Sequence↗
PubMed1988

Botulinum neurotoxin types A, B & E: pH induced difference spectra.

The alkaline pH induced difference spectra (270-310 nm) of three antigenically distinct forms of the botulinum neurotoxin (NT) types A, B and E were examined. When isolated from the cultures of Clostridium botulinum, type A NT is a fully toxic dichain (nicked) protein, type E is a mildly toxic single chain (unnicked) protein, and type B NT is a mixture of single and dichain proteins and near fully toxic. Trypsin nicks the single chain protein to the dichain and increases its toxicity (up to about 100 fold in type E). A strong difference spectrum peak at approximately 296 nm was found when types A, B or E NT were in the alkaline pH region. This peak was not observed at pH 4.0. For types A and B NT plots of difference absorptivity vs. pH were simple sigmoidal curves. The pK of phenolic moieties of tyrosine residues in both proteins were 10.9. Nearly all tyrosine residues in both proteins were ionized. The single chain type E, unlike type A and B NT, yielded a two step titration curve and pK values 11.3 and less than 7.5; about 60% of the total tyrosine residues present were ionized. The two step titration curve was not observed when the single chain protein was nicked with trypsin to the dichain type E NT. The titration curve of dichain type E NT, although complex, was more like those of type A and B NT.

Botulinum Toxins↗
PubMed1988

Circular dichroic and fluorescence spectroscopic study of the conformation of botulinum neurotoxin types A and E.

Botulinum neurotoxin (NT) is synthesized by Clostridium botulinum in any of seven antigenically distinct forms, called types A through G. Protease(s) endogenous to the bacteria, or trypsin, nicks the single chain protein to a dichain molecule which generally is more toxic. The conformation of dichain type A (nicked by endogenous protease), single chain type E, and dichain type E NT (nicked by trypsin) have been determined using circular dichroism (CD) and fluorescence spectroscopy. The high degree of ordered secondary structure (alpha helix 28%, beta sheet 42%, total 70%) found in type A NT at pH 6.0 was similar to that found at pH 9.0 (alpha 22%, beta 47%, total 69%). The secondary structure of the single chain type E NT at pH 6.0 (alpha 18%, beta 37%, total 55%) differed somewhat from these values at pH 9.0 (alpha 22%, beta 43%, total 65%). The dichain type E NT at pH 6.0 assumed a secondary structure (alpha 20%, beta 47%, total 67%) more similar to that of dichain type A than the single chain type E NT. Examination with the fluorogenic probe toluidine napthalene sulfonate revealed that the hydrophobicity of the type A and E NTs were higher at pH 9.0 than at pH 6.0. Also, the hydrophobicity of the dichain type E NT was higher than its precursor the single chain protein and appeared similar to that of the dichain type A NT. The CD and fluorescence studies indicate that conversion of the single chain type E NT to the dichain form (i.e. nicking by trypsin) induced changes in conformation.(ABSTRACT TRUNCATED AT 250 WORDS)

Botulinum Toxins↗
PubMed1988

Botulinum neurotoxin type B (strain 657): partial sequence and similarity with tetanus toxin.

The type B neurotoxin (NT) isolated from Clostridium botulinum (strain 657) behaved as a mixture of single (unnicked) and dichain (nicked) proteins, both of Mr approximately 150 kDa. When the dichain NT was reduced by mercaptoethanol, the two chains migrated in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) as separate polypeptides of Mr approximately 100 and 50 kDa that appeared similar to the heavy and light chains of other serotypes of botulinum NT. The N-terminal amino acid sequences of the two chains were determined. They were as follows: light chain: Pro-Val-Thr-Ile-Asn-Asn-Phe-Asn-Tyr-Asn-Asp-Pro-Ile-Asp-Asn-Asn-Asn-Ile- Ile-Met - Met-Glu-Pro-Pro-Phe-Ala-Arg-Gly-Met-Gly-Arg-Tyr-Tyr-Lys-Ala-Phe-Lys-Ile- Thr-Asp - Arg-Ile-Trp-Ile-; and heavy chain: Ala-Pro-Gly-Ile-X-Ile-Asp-Val-Asp-Asn-Glu-Asp-Leu-Phe-Phe-Ile-Ala-Asp-Ly s-Asn- Ser-Phe-Arg-Asp-Asp-Leu-. These two sequences matched exactly with those of the light and heavy chains of type B NT (strain Okra) of which only 16 and 18 residues were known (J. Biol. Chem. (1985) 260, 10461). The above sequences were different from those of type A NT. Immunoprecipitation reactions of type B NT isolated from strains 657 and Okra were indistinguishable against polyclonal anti-type B NT serum. These two preparations did not produce precipitin reactions with polyclonal anti-type A NT serum.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1988

Role of the overdrive sequence in T-DNA border cleavage in Agrobacterium.

The T-DNA of the Ti plasmid of Agrobacterium is flanked by 25-base-pair imperfect direct repeats that are required in cis for transfer to the genome of the plant host. Another sequence, designated overdrive, is located adjacent to the right-border repeats and functions in cis to enhance tumor formation. We have examined the effect of the overdrive sequence on the early steps in T-DNA processing. We report here that overdrive greatly enhances cleavage by the site-specific endonuclease in Agrobacterium, perhaps by directing the endonuclease to the adjacent border sequences. We also show by a gel mobility-shift assay that overdrive affinity-purified proteins from acetosyringone-induced Agrobacterium cells interact with T-DNA border and overdrive sequences. Further, we show that in vivo the virC operon enhances cleavage at the T-DNA borders, most likely by interaction between the VirC1 protein and the overdrive sequence.

Chromatography, Affinity↗
PubMed1987

An inhibitor RNA of translation from barley embryo.

A small molecular weight RNA isolated from barley embryos inhibits specifically protein synthesis initiation. It does not bind to Oligo (dT)-Cellulose indicating that it is devoid of long poly(A) stretches. It is a single stranded RNA as it is sensitive to pancreatic RNase. This is the first report of such an RNA in a plant system.

Animals↗
PubMed1987

Polyethylene glycol-induced heteroassociation of malate dehydrogenase and citrate synthase.

Studies by dynamic and total intensity light scattering, ultracentrifugation, electron microscopy, and chemical crosslinking on solutions of the pig heart mitochondrial enzymes, malate dehydrogenase and citrate synthase (separately and together) demonstrate that polyethylene glycol induces very large homoassociations of each enzyme, and still larger heteroenzyme complexes between these two enzymes in the solution phase. Specificity of this heteroassociation is indicated by the facts that heteroassociations with bovine serum albumin were not observed for either the mitochondrial dehydrogenase or the synthase or between cytosolic malate dehydrogenase and citrate synthase. The weight fraction of the enzymes in the mitochondrial dehydrogenase-synthase associated particles in the solution phase was less than 0.03% with the dilute conditions used in the dynamic light scattering measurements. Neither palmitoyl-CoA nor other solution conditions tested significantly increased this weight fraction of associated enzymes in the solution phase. Because of the extremely low solubility of the associated species, however, the majority of the enzymes can be precipitated as the heteroenzyme complex. This precipitation is a classical first-order transition in spite of the large particle sizes and broad size distribution. Ionic effects on the solubility of the heteroenzyme complex appear to be of general electrostatic nature. Polyethylene glycol was found to be more potent in precipitating this complex than dextrans, polyvinylpyrrolidones, ficoll, and beta-lactoglobulin.

Animals↗
PubMed1987

Antifilarial effect of Zingiber officinale on Dirofilaria immitis.

Dogs, naturally infected with Dirofilaria immitis, were treated with the residues of the alcoholic extracts of the rhizomes of Zingiber officinale (ginger). Twelve subcutaneous injections of the extract given at 100 mg/kg reduced microfilarial concentration in blood by a maximum of 98%. Fifty five days after the last injection there was 83% reduction in microfilarial concentration suggesting partial destruction of adult worms. Half of the treated dogs showed some lethargy at the beginning of treatment possibly due to the mass annihilation of microfilariae in blood.

Animals↗
PubMed1987

Regulation of Protein Synthesis in Plant Embryo by Protein Phosphorylation : I. Purification and Characterization of a cAMP-Independent Protein Kinase and Its Endogenous Substrate.

A cyclic AMP-independent protein kinase, which strongly inhibits in vitro protein synthesis, was purified to homogeneity from barley embryo by affinity and ion exchange chromatography. The M(r) of the purified enzyme is 95,000 with two nonidentical subunits of M(r) 58,000 and 39,000. The enzyme activity is not stimulated by cAMP, cGMP, or calmodulin. The endogenous phosphate acceptor of this kinase is a protein of M(r) 52,000, was isolated by purified protein kinase immobilized Sepharose column. Using antibodies raised against this protein kinase, the levels of the enzyme during embryogenesis and germination are determined. An inverse relationship has been observed between protein kinase level and rate of protein synthesis.

Journal Article↗
PubMed1987

The effect of submaxillariectomy on the uterine peroxidase activity and [14C]phenylalanine incorporation into uterine protein in rats.

Surgical removal of submaxillary glands in immature female rats caused an increase in size and about 3-fold increase in dry and wet weight of the uterus compared to that of the sham operated animals of the same age group. Histological examination reveal a significant increase in the diameter of the uterus with considerable elongation of the luminal epithelium from cubical to columnar in the experimental group. Biochemical studies showed that the uterine peroxidase, a marker enzyme for oestrogen action, increased (P less than 0.01) on submaxillariectomy. Incorporation of [14C]phenylalanine into the nuclear fraction of uterus was also enhanced significantly on removal of submaxillary glands. The elevation of peroxidase activity as well as of [14C]phenylalanine incorporation into the nuclear fraction due to removal of submaxillary glands were abolished in ovariectomized rats suggesting the involvement of ovarian hormones. The results show that oestrogen was responsible for all the above mentioned changes, whereas progesterone had little effect. Results further suggest the existence of a factor in the submaxillary glands through which they exert an effect on the uterus and ovary.

Animals↗