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Biomedical subjects

S Basu

Publications and source records attributed to S Basu.

At least 397 records · Page 22Linked to original sources
PubMed1987

Clinical and endocrine responses to embryonic and fetal death induced by manual rupture of the amniotic vesicle during early pregnancy in cows.

Pregnancy was terminated in 4 cows by manual rupture of the amniotic vesicle on day 41 (n = 1) and day 46 (n = 3) after insemination. Each cow was necropsied 36 days after vesicle rupture, by which time only one cow had come into estrus. Luteal activity, monitored daily by plasma progesterone assay, was still evident in 2 cows 35 days after fetal death; in the remaining 2 cows, regression of the corpus luteum (CL) was achieved at 28 and 32 days, respectively. Uterine release of prostaglandin F2 alpha (PGF2 alpha), measured as the 15-keto metabolite (PGFM) PGF2 alpha, was monitored by a plasma sampling schedule; specimens were obtained every 4 hours. There were no appreciable releases of PGF2 alpha associated with fetal death. The first appreciable PGF2 alpha release in episodic form was seen only in conjunction with CL regression. In all cows, a palpable membrane slip was evident for 18 days after rupture of the amniotic vesicle, although at that time, uterine resilience was diminished in the 2 cows in which the CL subsequently regressed. After 18 days, the uterus was noticeably edematous and fluid-filled in all cows; in 1 of the cows with a regressed CL, the uterus had returned to prepregnancy size and tone by day 33.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Comparison of enterobacterial common antigen from different species by serological techniques.

Enterobacterial common antigen (ECA) was isolated from a number of selected species (including Salmonella montevideo, Shigella sonnei and Plesiomonas shigelloides) using the extraction method described by Männel and Mayer [Eur. J. Biochem. 86, 361-370 (1978)]. ECA of all these species behaved identically in enzyme-linked immunosorption assay (ELISA) and in its inhibition using monoclonal anti-ECA antibodies. Immunoblotting showed a ladder-like pattern of at least 20 bands for all preparations tested. ECA modified at its lipid moiety (e.g. by phospholipases A2 and D or by mild acid hydrolysis) lost its coating capacity leaving, however, the serological reactivity as detected by inhibition assays intact. In contrast, reduction of the carboxylic groups of 2-acetamido-2-deoxy-D-mannopyranosyluronic acid destroyed the serological reactivity. Deacylated ECA was also not detectable in immunoblotting. Chemical reacylation restored the reactivity of deacylated ECA in ELISA and in immunoblot and thus proved the essential function of fatty acids for the physicochemical properties of the molecule. 2-Acetamido-2-deoxy-D-glucopyranose was identified as the reducing end of the ECA sugar chain after splitting off the lipid moiety by phospholipase D.

Acylation↗
PubMed1987

Chemical characterization of enterobacterial common antigen isolated from Plesiomonas shigelloides ATCC 14029.

Serologically characterized samples of enterobacterial common antigen (ECA) from Plesiomonas shigelloides, Salmonella montevideo and Shigella sonnei were investigated by chemical methods including methylation and NMR techniques. All showed the same sugar composition and contained a lipid moiety with palmitic acid as main fatty acid and with a phosphodiester group. Additional enzymatic studies, reported in the preceding paper, provided evidence that the lipid moiety is an L-glycerophosphatidyl residue attached via a phosphodiester linkage to C-1 of GlcNAc as the reducing end of the ECA sugar chain. ECA of P. shigelloides showed the best-resolved 13C-NMR spectra, especially after the removal of non-stoichiometric O-acetyl groups at C-6 of GlcNAc of the ECA repeating unit and of the lipid moiety by mild acid hydrolysis (0.01 M HCl, 100 degrees C, 10 min). Subsequent 13C-NMR studies were therefore carried out with the mild-acid-treated ECA of P. shigelloides which allowed a tentative assignment of all resonances of the ECA repeating unit. 13C-NMR spectra of Salmonella and Shigella ECA were essentially the same as those obtained with Plesiomonas ECA. The same trisaccharide repeating unit was encountered as demonstrated previously in the cyclic form of ECA isolated from S. sonnei by Dell et al. [Carbohydr. Res. 133, 95-104 (1984)]. Methylation analysis, however, afforded small amounts of terminal GlcNAc thus proving, in combination with the demonstration of the attached lipid moiety, an acyclic nature of ECA from P. shigelloides and from the two enterobacterial species. The question of whether the cyclic form co-exists in S. sonnei phase I and possibly in other enterobacterial species or, whether it had been formed during extraction as an artifact, has not yet been answered. The way in which ECA was isolated in our studies would preclude the presence of a non-amphiphilic (cyclic) polysaccharide. The finding that the sugar chain of ECA is attached to an L-glycerophosphatidyl residue is in full corroboration with serological, enzymatic and gel electrophoretic studies shown in the preceding paper and with the character of ECA as a surface antigen being anchored by hydrophobic interactions in the outer membrane of Enterobacteriaceae and P. shigelloides.

Antigens, Bacterial↗
PubMed1987

Glycolipids.

Explore the source record for details and available documents.

Animals↗
PubMed1987

Prostaglandin biosynthesis and its regulation in the bovine endometrium: A comparison between nonpregnant and pregnant status.

Prostaglandin F(2alpha) (PGF(2alpha)), an arachidonic acid metabolism product of the prostaglandin synthetase pathway, is synthesized and released from the endometrium during luteolysis in nonpregnant animals. When proper conception occurs, the synthesis and release pattern is changed to maintain the corpus luteum (CL) function. The biosynthesis of prostaglandins in the bovine endometrium was highest in the microsomes but of low order. In nonpregnancy, the formation of prostaglandins from labelled precursor acid was higher than in pregnancy. Besides the prostaglandin synthetase, an inhibiting activity on the conversion of arachidonic acid to prostaglandins was found in both the nonpregnant and pregnant endometrium. During luteolysis (Day 17), a low inhibiting capacity was seen in comparison with other days of the estrous cycle (Days 1, 4 and 14). The inhibitory capacity was very high on Days 16 to 20, 25, and 31 of pregnancy. In the nonpregnant endometrium at Day 17, a very low inhibitor potency, calculated as IC(50) values, was found both in the cytoplasma and in the microsomes, whereas during early pregnancy (Days 17, 18, and 20) both cytoplasma and microsomes possessed very high inhibitor potency. This finding indicates that the bovine endometrium contains both prostaglandin synthetase and an unknown potent inhibitor of prostaglandin biosynthesis that regulates prostaglandin biosynthesis both during the estrous cycle and early pregnancy.

Journal Article↗
PubMed1987

Regulation of alpha- and beta-tubulin mRNAs in rat brain during synaptogenesis.

Developmental alterations in alpha- and beta-tubulin mRNA in polysomes from brains of -3 days (fetal) to 30-day-old rats were quantitated by using well-characterized chicken alpha- and beta-tubulin cDNA probes, pT1 and pT2 having 80-90% homology with rat sequences. Northern blot analysis revealed a single major (greater than 95%) 1.8 kb mRNA for both alpha- and beta-tubulin. Quantitation by slot hybridization indicates a virtually coordinate expression of alpha- and beta-tubulin mRNA with a maximal level around day 5 after birth, which represents the mid-phase of synaptogenesis.

Animals↗
PubMed1987

Mutual and self-sensitivity among antibiotically active mutant derivatives from the inactive degenerate Aspergillus versicolor N5.

Antibiotically active producer mutants derived from the spontaneous degenerate parent Aspergillus versicolor N5 possessed not only mutual but also self-sensitive activity. The producer mutants, like the inactive parent, were only 3.5-fold less sensitive than the most sensitive unrelated organism, Trichophyton rubrum. The germination of spores is generally more sensitive than growth of vegetative cells. The antifungal spectrum of these mutual and self-sensitive mutants was fairly wide, unlike the host range specificity of bacteriocinogenic strains acting on organisms closely related to the producers. The self and mutual growth inhibitory principle was finally identified as the antibiotics mycoversilin and versilin in the case of producer mutants (N5)17 and N5T10(7), respectively, or Vx, an antibiotic of unknown molecular species, in the case of another producer mutant N5T10(8). Thus self-sensitivity, instead of self-resistance, of these antibiotically active mutant derivatives is a unique property among filamentous fungi in having simultaneously expressed two loci of contradictory functions, one for synthesis of, and the other for sensitivity towards, the same or related antibiotics.

Antifungal Agents↗
PubMed1987

Physico-chemical interaction of mycobacillin with Aspergillus niger protoplast membrane, the site of its action.

Mycobacillin partially quenched the strong fluorescence when 1-anilino naphthalene 8-sulfonate (ANS) was added to protoplast or plasma membrane but is without any effect on weak fluorescence when added to cell-free extract. There are two classes of ANS binding sites on protoplast or plasma membrane of which one class is sensitive to mycobacillin, being competitively abolished by it. Mycobacillin also non-competitively inhibits the binding of pyrene, a lipid specific probe. Thus it follows from the inhibition by mycobacillin of ANS or pyrene binding to protoplast or plasma membrane that the site of action of the antibiotic is located in the plasma membrane. Interaction between mycobacillin and the plasma membrane is physico-chemical in nature.

Anilino Naphthalenesulfonates↗
PubMed1986

Purification and kinetic studies of an alpha-L-fucosidase of Venus mercenaria.

An alpha-L-fucosidase activity has been isolated from the liver (hepatopancreas) of the common edible clam, Venus mercenaria, and has been purified approximately 300-fold (11% yield) by affinity chromatography on agarose-epsilon-amino-caproylfucosamine. Isoelectric focusing profiles were heterogeneous, revealing several isoenzymes. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicated the presence of a single subunit of Mr 50,000. The purified enzyme preparation contained only trace amounts of other alpha- and beta-D-glycosidases tested. In addition to p-nitrophenyl alpha-L-fucopyranoside, the enzyme hydrolyzed natural substrates such as fucose-containing milk pentasaccharides, thyroglobulin glycopeptides, human salivary glycoproteins, and blood-group-active glycosphingolipids. The enzyme preparation had a broad pH optimum range between 4.5 and 5.5. The apparent Km value with respect to p-nitrophenyl alpha-L-fucopyranoside was 0.26mM.

Animals↗
PubMed1986

Selective action of mycobacillin on the uptake of releasable cell materials by Aspergillus niger.

The uptake of normally releasable (i.e. releasable in the absence of the antibiotic) cell constituents (namely lysine, proline, ATP, Pi, Na+, K+ and Ca2+) by sensitive cells of Aspergillus niger that occurs in the absence of mycobacillin is gradually enhanced with increase in concentration of the antibiotic until the uptake attains the maximum. With still higher concentrations the uptake decreases until it becomes the same as in the control without mycobacillin. Uptake follows saturation kinetics both in the absence and in the presence of the antibiotic. Mycobacillin significantly increases Vmax. for uptake with any effect on Km, Mycobacillin has no action on the uptake of non-releasable materials.

Adenosine Triphosphate↗
PubMed1986

Specific binding of monomeric bacteriophage T3 and T7 RNA polymerases to their respective cognate promoters requires the initiating ribonucleoside triphosphate (GTP).

Bacteriophage T3 and T7 RNA polymerases are monomeric proteins of Mr of about 100,000. Each polymerase has stringent specificity for its own promoters that is present only on the homologous phage DNA template. Neither enzyme recognizes the heterologous phage promoters or Escherichia coli RNA polymerase promoters. In the present study, the interaction of T3 and T7 RNA polymerases with their respective cognate promoters was studied by DNase I footprinting techniques. These studies revealed an absolute requirement for the initiating nucleotide (GTP) for each phage RNA polymerase to bind specifically to and protect its cognate promoter from DNase I digestion. In the absence of the initiating nucleotide, both enzymes randomly bind DNA with lower affinity. No other nucleotide can substitute for GTP; however, the addition of GTP + ATP, which causes the synthesis of a hexamer RNA (pppGpGpGpApGpA), makes the DNA-RNA-protein complex highly stable. Nitrocellulose filter binding studies confirmed these observations. On the basis of these results we propose that the binding of the initiating nucleotide (in this case, GTP) drives the phage RNA polymerase into an "initiation conformation" in which the random DNA-binding property of the enzyme is converted to a promoter-specific recognition, and the polymerase is primed to initiate transcription.

Bacteriophage lambda↗
PubMed1986

Biosynthesis in vitro of a globoside containing a 2-acetamido-2-deoxy-beta-D-galactopyranosyl group (1----3)-linked and Forssman glycolipid by two N-acetylgalactosaminyltransferases from chemically transformed guinea pig cells.

Two N-acetylgalactosaminyltransferase activities (GalNAcT-2 and GalNAcT-3) have been characterized in chemically transformed, cultured guinea-pig cell lines (104C1 and 106B). Line 104C1 is a benz[a]pyrene-transformed tumorigenic variant, whereas line 106B is a 7,12-dimethylbenz[a]anthracene-transformed nontumorigenic variant obtained from fetal guinea-pig cells at 43 days of gestation. The GalNAcT-2 (UDP-GalNAc:GbOse3Cer beta-N-acetylgalactosaminyltransferase) isolated from both 104C1 and 106B cells catalyzed the transfer of Gal-NAc from UDP-GalNAc to the 3H-labeled terminal galactose group of Gb3 [( 6-3H]Gal alpha 1----4Gal beta 1----4Glc----Cer). The 3H-labeled globoside was purified and then subjected to exhaustive methylation. After acetolysis, the partially methylated sugars were separated by two-dimensional, thin-layer chromatography. 3H-Label was detected in two major areas, 2,4,6-tri-O-Me-Gal (40%) and 2,3,4,6-tetra-O-Me-Gal (46%). In a separate experiment, 80% of the GalNAc was released when labeled GbOse4Cer [( 3H]GalNAc----Gal alpha 1----4Gal beta 1----4Glc----Cer) was treated with purified clam beta-hexosaminidase. The present results establish the formation of a beta-D-GalpNAc-(1----3) linkage in the terminal region of the biosynthesized globoside. GalNAcT-3 activity (UDP-GalNAc:GbOse4Cer alpha-GalNAc-transferase), which catalyzes the transfer of GalNAc from UDP-[14C]- or -[3H]GalNAc to GbOse4Cer (GalNAc beta 1----3Gal alpha 1----4Gal beta 1----4Glc----Cer), was three times higher in 106B cells than in 104C1 cells. The isolated, purified radioactive product formed an immunoprecipitin line against rabbit anti-Forssman antibody.

Acetylgalactosamine↗
PubMed1986

A single step purification of a sialic acid binding lectin (AchatininH) from Achatina fulica snail.

A sialic acid binding lectin, AchatininH, was purified in single step from the hemolymph of the land snail, Achatina fulica, by the affinity chromatography on sheep submaxillary mucin coupled to Sepharose 4B. The yield of the lectin was found to be 3 mg from 100 ml of hemolymph. The homogeneity of the lectin was established by alkaline gel electrophoresis, immunodiffusion, immunoelectrophoresis and analytical isoelectrophoresis. The molecular weight of the native protein was 242,000, having identical subunits of Mr 15,000. The lectin agglutinated rabbit erythrocytes in the presence of Ca2+. The inhibition study clearly suggests that the binding site of the lectin recognizes sialic acid as the immunodominant sugar. This was further confirmed by the observation that there was a marked decrease of agglutinating activity of the lectin with neuraminidase treated rabbit erythrocytes and asialofetuin was unable to inhibit the activity of AchatininH. Among the inhibitors used the glycoconjugate containing alpha 2----6 linkages of N-acetylneuraminic acid with subterminal galactopyranose or 2-acetamido-2-deoxy-galactopyranose residue was found to be better inhibitor than that containing alpha 2----3 linkages of N-acetyl neuraminic acid. Besides that sialoglycoprotein containing both N and O type of glycosidic linkages plays an important role in binding with the lectin. Fetuin was found to be the best inhibitor.

Animals↗
PubMed1986

Lipopolysaccharide of Providencia rettgeri. Chemical studies and taxonomical implications.

The chemical constitutional analysis of the lipopolysaccharide (LPS) isolated from Providencia rettgeri was carried out. Polyacrylamide gel electrophoresis using sodium dodecylsulfate or sodium deoxycholate showed that the lipopolysaccharide mostly consisted of short sugar chains. The lipid A was precipitated out after mild acid hydrolysis of LPS. From the supernatant degraded polysaccharide and unsubstituted core fractions were isolated. Compositional analysis of the core material revealed the presence of galacturonic acid, galactose, glucose, glucosamine, L-glycero-D-manno-heptose, 3-deoxy-D-manno-octulosonic acid, alanine and phosphorus. Methylation analysis of the core material indicated the presence of terminal units of glucose, galacturonic acid and glucosamine. The chemical structure of the lipid A was elucidated. It constitutes a beta-1,6-glucosamine disaccharide substituted on either side by ester and glycosidically-bond phosphate residues. The ester-bound phosphate was found to be substituted by a 4-amino-4-deoxy-L-arabinosyl residue. The amino groups of the backbone disaccharide are N-acylated by 3-O-(14:0)14:0 and 3-O-14:0. Two hydroxyl groups of the disaccharide are esterified by 3-O-(14:0)14:0 and 3-O-14:0. The taxonomical importance of these structural details will be discussed.

Amino Sugars↗