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D Chatterjee

Publications and source records attributed to D Chatterjee.

At least 37 records · Page 2Linked to original sources
PubMed1991

Synthesis of allyl glycosides for conversion into neoglycoproteins bearing epitopes of mycobacterial glycolipid antigens.

Neoglycoproteins bearing key glycosyl substituents of several glycopeptidolipid antigens of pathogenic Mycobacterium species have been synthesized. Allyl glycosides of the terminal 6-deoxyhexose-containing units of the antigens were prepared, with appropriate ether and ester substituents in place. Ozonolysis of the allyl glycosides was then followed by reductive coupling with epsilon-amino groups of lysine residues in bovine serum albumin, using sodium cyanoborohydride at pH 7.8. The resulting neoglycoproteins emulated the antigenicity of the native molecule in several serological tests.

Antigens, Bacterial↗
PubMed1991

Structure of the glycopeptidolipid antigen of serovar 20 of the Mycobacterium avium serocomplex, synthesis of allyl glycosides of the outer di- and tri-saccharide units of the antigens of serovars 14 and 20, and serology of the derived neoglycoproteins.

The tetrasaccharide hapten released from the glycopeptidolipid (GPL) antigen of Mycobacterium avium serovar 20 has been characterized as O-(2-O-methyl-alpha-D-rhamnopyranosyl)-(1----3)-O-(2-O-methyl-alpha-L- fucopyranosyl)-(1----3)-alpha-L-rhamnopyranosyl-(1----2)-6-deoxy-L-talos e. Syntheses are reported of allyl glycosides of the outer disaccharide unit of this hapten, O-(2-O-methyl-alpha-D-rhamnopyranosyl)-(1----3)-2-O-methyl-alpha-L-fu copyranose , and also of the outer di- and tri-saccharide units of the GPL antigen of M. avium serovar 14, O-(N-formyl-alpha-L-kansosaminyl)-(1----3)-2-O-methyl-alpha-D-rham nopyranose and O-(N-formyl-alpha-L-kansosaminyl)-(1----3)-O-(2-O-methyl-alpha-D- rhamnopyranosyl)-(1----3)-2-O-methyl-alpha-L-fucopyranose. The key steps in the latter synthesis involve the preparation of allyl 4-azido-4,6-dideoxy-3-C-methyl-2-O-methyl-alpha-L-mannopyranoside as a precursor for the N-formylkansosamine unit, followed sequentially by conversion into and use of a trichloroacetimidate as glycosyl donor for di- and tri-saccharide formation, O-deacylation, reduction, and N-formylation. The allyl glycosides, representative of the haptens from both serovars, have been converted into neoglycoproteins (NGPs) and their serological activities have been compared in the light of the structural relationship between them.

Antigens, Bacterial↗
PubMed1991

Structural features of the arabinan component of the lipoarabinomannan of Mycobacterium tuberculosis.

The recent availability of pure lipoarabinomannan (LAM) from Mycobacterium spp. has resulted in its implication in host-parasite interaction, which events may be mediated by the presence of a phosphatidylinositol unit at the reducing end of LAM. Herein we address the structure of the antigenic, nonreducing end of the molecule. Through the process of 13C NMR analysis of the whole molecule and gas chromatography/mass spectrometry of alditol acetates derived from the differential per-O-alkylated lipopolysaccharide, the majority of the arabinosyl residues were recognized as furanosides. Second, through analysis of per-O-alkylated oligoarabinosyl arabinitol fragments of partially hydrolyzed LAM, it was established that the internal segments of the arabinan component consists of branched 3,5-linked alpha-D-arabinofuranosyl (Araf) units with stretches of linear 5-linked alpha-D-Araf residues attached at both branch positions, whereas the nonreducing terminal segments of LAM consist of either of the two arrangements, beta-D-Araf-(1----2)-alpha-D-Araf-(1----5)- alpha-D-Araf---- or [beta-D-Araf-(1----2)-alpha-D-Araf-(1----]2---- (3 and 5)-alpha-D-Araf----. Since this latter arrangement also characterizes the terminal segments of the peptidoglycan-bound arabinogalactan of Mycobacterium spp., we propose that mycobacteria elaborate unique terminal arabinan motifs in two distinct settings. In the case of the bound arabinogalactan, these motifs provide the nucleus for the esterified mycolic acids, entities which dominate the physicochemical features of mycobacteria and their peculiar pathogenesis. In the case of LAM, these motifs, non-mycolylated, are the dominant B-cell antigens responsible for the majority of the copious antibody response evident in most mycobacterial infections.

Antigens, Bacterial↗
PubMed1991

Cell cycle-dependent coupling of the calcitonin receptor to different G proteins.

Calcitonin is a calcium regulating peptide hormone with binding sites in kidney and bone as well as in the central nervous system. The mechanisms of signal transduction by calcitonin receptors were studied in a pig kidney cell line where the hormone was found to regulate sodium pumps. Calcitonin receptors activated the cyclic adenosine monophosphate (cAMP) or the protein kinase C (PKC) pathways. The two transduction pathways required guanosine triphosphate (GTP)-binding proteins (G proteins) (the choleratoxin sensitive Gs and the pertussis toxin sensitive Gi, respectively) and led to opposite biological responses. Moreover, selective activation of one or the other pathway was cell cycle-dependent. Therefore, calcitonin may induce different biological responses in target cells depending on their positions in the cell cycle. Such a modulation of ligand-induced responses could be of importance in rapidly growing cell populations such as during embryogenesis, growth, and tumor formation.

Adenylyl Cyclases↗
PubMed1991

Chemical synthesis and seroreactivity of a neoantigen containing the oligosaccharide hapten of the Mycobacterium tuberculosis-specific phenolic glycolipid.

The report of a major triglycosyl phenol phthiocerol (phenolic) glycolipid in some strains of Mycobacterium tuberculosis that resembles the phenolic glycolipid I of Mycobacterium leprae raised the prospects of a specific serodiagnostic tool for human tuberculosis. The terminal diglycosyl unit of the M. tuberculosis product was synthesized and converted to a corresponding neoglycoprotein, the O-(2,3,4-tri-O-methyl-alpha-L-fucopyranosyl)-(1----3)-O-alpha-L- rhamnopyranosyl)-(1----9)-oxynonanoyl-bovine serum albumin, and applied, in ELISA, to sera from individuals with tuberculosis. Although the correlation coefficient between the synthetic product and the native glycolipid was excellent, the seroreactivity rate of tuberculous sera was disappointing; only 24 of 119 sera from tuberculosis patients showed evidence of anti-glycolipid antibodies. In isolates of M. tuberculosis from tuberculosis patients the glycolipid was present in only 1 of 11. A partially deglycosylated version was present in two other isolates; however, most isolates lacked the glycolipid. Accordingly, while the results, unlike those of others, do not portend a future for this form of serodiagnosis in the management of tuberculosis, they offer intriguing hints as to the basis of the variable immunogenicity and pathogenicity of strains of M. tuberculosis.

Antibodies, Bacterial↗
PubMed1991

Prevalence of serum antibody to the type-specific glycopeptidolipid antigens of Mycobacterium avium in human immunodeficiency virus-positive and -negative individuals.

An enzyme-linked immunosorbent assay was constructed by using as antigens the type-specific immunodominant glycopeptidolipids of selected serotypes of Mycobacterium avium. This assay system was used to determine the prevalence of raised antibody levels to these antigens in groups of controls, human immunodeficiency (HIV)-negative and -positive homosexual men, and HIV-negative patients with active M. avium infections as a possible indicator of potential exposure and/or colonization by M. avium in these individuals. The results indicate that while antibody levels were raised in only 2.4% of control individuals, 33% of HIV-negative homosexual men and 44% of HIV-positive patients exhibited raised levels. Moreover, further examination of the HIV-positive group revealed no correlation between antiglycopeptidolipid antibody activity and helper T cell numbers. These data indicate that exposure to M. avium is prevalent among the homosexual male population, regardless of their HIV status. Moreover, the data are suggestive that the emergence of disseminated M. avium disease in HIV-positive patients may sometimes arise from earlier colonization, rather than as a newly acquired infection during terminal immunodeficiency.

Adult↗
PubMed1990

Human platelet dense granules: improved isolation and preliminary characterization of [3H]-serotonin uptake and tetrabenazine-displaceable [3H]-ketanserin binding.

An improved method for the isolation of human platelet dense granules was developed. A good yield (45%) of highly enriched (69-fold, based on serotonin content) dense granules was obtained after mild sonication and Percoll gradient centrifugation. The method has facilitated characterization of the granule, permitting the first report of Km and Vmax values for [3H]-serotonin uptake, as well as the first determination of Kd and Bmax values for tetrabenazine-displaceable [3H]-ketanserin binding, in the human platelet dense granule. The rates and affinities (Vmax 1.45 nmol/mg/min, Km 0.93 uM) of [3H]-serotonin uptake were similar to those previously reported for porcine dense granules. Tetrabenazine-displaceable [3H]-ketanserin binding was observed with a Kd (9.4 nM) similar to, and a Bmax (5.4 pmol/mg) approximately 10-fold lower than, that previously seen in bovine chromaffin granules.

Acid Phosphatase↗
PubMed1990

Size variation of mastoid air cell system in Indian people at different age groups: a radiographic planimetric study.

A radiographic planimetric study of mastoid air cell system was carried out on 100 normal human subjects of which 50 were males and 50 females--who were further subdivided into five age groups. They had no history of past ear disease or any other clinical ENT abnormality. The mean area of the mastoid air cell system was measured planimetrically on X-rays and the data analysed according to age and sex. It was 12.05 +/- 0.67 cm2 in males and 11.45 +/- 0.70 cm2 in females (which are more or less the same as that of Western people). The size of the cranial bones has no apparent role in the size variation of the mastoid air cell system. The development of the latter was very rapid up to 10 years of age in both sexes and it continued even after 20 years of age but at a much slower rate.

Adolescent↗
PubMed1990

The hyperserotonemia of autism.

The planned and ongoing studies of platelet function and composition should allow us to better define the alteration which we presume to be present in platelets of autistic subjects. Although much of the research focuses on serotonergic aspects, the more general research should permit a better delineation of the extent of the alteration and will protect against a premature narrowing of the inquiry. The methodological development which has been a necessary aspect of the work should contribute to an improved understanding of platelet function and composition, as well as result in improved clinical tools for the assessment of platelet functioning in neuropsychiatric disorders and hematology. As an example, improvements in short-term in vitro storage conditions to stabilize aggregation and shape change responses over time were found to be necessary, and are probably critical to an optimal comparison of these phenomena across groups. The identification of the platelet alteration which is responsible for the hyperserotonemia of autism should prove useful in several ways. It would be expected that assessment of the altered function would provide a marker with less overlap with the normal population than the multidetermined measure of blood 5-HT. Determination of the specific protein(s) involved in the altered platelet should lead directly to gene probes and chromosomal location. These, in turn, should prove useful for neonatal screening, subtyping, and more powerful genetic and family studies. Work of this sort might also allow early intervention and improved treatment. Finally, characterization of the physiological alteration would provide a basis for focusing studies of brain neurochemistry and should, as well, suggest modes of neuropharmacological intervention. The confidence that one can have in the basic finding of hyperserotonemia in autism and the potential benefits to be derived from its explication make further research in this area of great interest.

Adolescent↗
PubMed1989

Bay K8644 like activity of an antibody against a 60 kDa tubular membrane protein.

Partial purification of the dihydropyridine receptor from rat skeletal muscle demonstrated mainly a 60 kDa band in SDS-polyacrylamide gel. An antibody raised against that protein behaved as a calcium channel agonist viz. Bay K8644. The affinity purified antibody, when added to cultured heart cells, increased the beat rate 40-80% depending on the titer of the antiserum. The antibody also woke up the beats of the cells previously blocked with the channel antagonist, nifedipine. Immunoblot analysis indicated that the receptor of this antibody in heart cell membrane is also a 60 kDa protein.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1989

Reversible suppression of c-myc expression in a human colon carcinoma line by the anticancer agent N-methylformamide.

The anticancer agent N-methylformamide (NMF), which at high concentrations (170 mM) induces cultured DLD-1 Clone A human colon carcinoma cells to increase their doubling times and lose their tumorigenicity in nude mice (Cordeiro, R.F., and Savarese, T.M. Cancer Res., 46: 1297-1305, 1986), suppresses the expression of the c-myc protooncogene in these cells in a dose- and time-dependent manner. This suppression involves an inhibition of c-myc transcription rather than an increased degradation of c-myc mRNA, and is reversed if NMF is removed from the culture medium. Expression of the glyceraldehyde 3-phosphate dehydrogenase gene, which is thought to be constitutive, is phosphate dehydrogenase gene, which is thought to be constitutive, is relatively unaffected by NMF treatment. The NMF-mediated decrease in c-myc expression may be associated with the ability of this agent to increase the doubling time of these cells, but there is no direct temporal link between the loss of c-myc expression and the NMF-induced loss of tumorigenicity.

Antineoplastic Agents↗
PubMed1989

Sequence divergence and open regions of RNA secondary structures in the envelope regions of the 17 human immunodeficiency virus isolates.

Genetic variation during the course of infection of an individual is a remarkable feature of the acquired immune deficiency syndrome (AIDS) disease. This variation has been studied for the envelope protein encoding regions of seventeen different sequences from various isolates of human immunodeficiency virus (HIV) using multiple sequence comparison and calculation of variability. The open regions with little intramolecular base pairing in these envelope sequences are predicted by a recently developed statistical method. The minimum length L for a run of hypervariable sites, conserved sites, or open regions that gives significance at the 1% (or 0.1%) level is then determined by a scan statistical method. The results show that significant clusters of open regions predicted at the RNA levels correlate with significant clusters of hypervariable sites in the HIV envelope gene. Those significant genomic variations in HIVs seem to be manifested mainly in the extracellular portion of the envelope protein. Twelve potential antigenic determinants are predicted using an antigenic index method. Interestingly, the majority of the significant hypervariable regions in the exterior envelope protein (gp120) were predicted potential epitopes.

Amino Acid Sequence↗
PubMed1989

Generation of monoclonal antibodies to the specific sugar epitopes of Mycobacterium avium complex serovars.

Monoclonal antibodies have been generated to the unique distal sugar epitopes on the oligosaccharide haptens of the glycopeptidolipid antigens of clinically prominent members of the Mycobacterium avium serocomplex. Thus, antibodies are described that recognize the distal O-acetyl-alpha-L-rhamnopyranosyl residue of the specific glycopeptidolipid of M. avium serovar 1, the 4-O-acetyl-2,3-di-O-methyl-alpha-L-fucopyranose of serovar 2, the 4-O-methyl-alpha-L-rhamnopyranosyl-(1----4)-2-O-methyl-alpha-L- fucopyranosyl unit of serovar 4, the 4,6-(1'-carboxyethylidene)-3-O-methyl-beta-D-glucopyranosyl unit of serovar 8 [and the 4,6-(1'-carboxyethylidene)-beta-D-glucopyranosyl residue of serovar 21], and the 4-O-acetyl-2,3-di-O-methyl-alpha-L-fucopyranosyl-(1----4)-beta-D- glucuronopyranosyl unit of serovar 9. Epitope definition was arrived at through use of the pure, chemically defined glycopeptidolipid antigens and neoglycoproteins containing the chemically synthesized distal sugars of some select serovars. These monoclonal antibodies combined with the already published information on the structure of the antigen determinants and the tools used to arrive at these structures provide powerful means for fundamental studies on the role of these antigens in immunopathogenesis and for the precise mapping of the epidemiology of opportunistic infections caused by M. avium.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Phenolic glycolipids of Mycobacterium bovis: new structures and synthesis of a corresponding seroreactive neoglycoprotein.

The glycolipid that characterizes the majority of isolates of Mycobacterium bovis and that has come to be known as M. bovis-identifying lipid is the phenolic glycolipid mycoside B described in the literature by others. However, when mycoside B obtained from M. bovis BCG, field isolates, and infected tissues was examined in detail, it was shown to be different from that described in the literature in some important respects. In particular, the glycosyl substituent is 2-O-methyl-alpha-L-rhamnopyranose rather than 2-O-methyl-beta-D-rhamnopyranose. With this information, a seroreactive neoglycoprotein (neoantigen) containing the 2-O-methyl-alpha-L-rhamnopyranosyl substituent suitable for the serodiagnosis of bovine tuberculosis was synthesized. M. bovis also contains other minor seroreactive phenolic glycolipids, one of which is a deacylated form of mycoside B and another of which contains an alpha-L-rhamnopyranosyl unit rather than 2-O-methyl-alpha-L-rhamnopyranose.

Animals↗
PubMed1989

Structure and function of mycobacterial glycolipids and glycopeptidolipids.

Earlier work from this and other laboratories has revealed the presence within Mycobacterium spp. of three classes of glycolipid antigens which we have called the glycopeptidolipids, the lipooligosaccharides and the phenolic glycolipids. Representative structures of each from different species and sub-species have been proposed. More recently, new variants of these antigens and older structures have been analyzed by Fourier transform infrared, NMR, particularly at high temperatures, and, most notably, by fast atom bombardment and Californium desorption mass spectrometry. Extraordinary novelty and diversity were revealed, particularly at the distal non-reducing end of the oligosaccharide chains, marked by the presence of new branched-chain sugars, amino sugars and sugar acids. These epitopes and monoclonal antibodies to them have been used for the critical identification of mycobacteria. In addition, the pure antigens are the basis of specific serological tests for various mycobacterioses. The resurgence of interest in "atypical" mycobacteria stems from their occurrence as opportunistic pathogens in many patients with acquired immunodeficiency syndrome, although they have long been associated with pulmonary and other organ infections. Foremost among these mycobacteria are serovars of the Mycobacterium avium-Mycobacterium intracellulare complex (the M. avium complex). The surface antigens which differentiate these serovars are glycopeptidolipids, related to "mycoside C" and, accordingly, composed of a glycosylated lipopeptide "core", fatty acyl-D-Phe-D-alloThr-D-Ala-L-acanyl-O- (3,4-di-O-methyl-alpha-L-rhamnopyranoside), to which a haptenic oligosaccharide is linked at the threonine substituent; this oligoglycosyl unit is the source of type specificity.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Synthesis and immunoreactivity of neoglycoproteins containing the trisaccharide unit of phenolic glycolipid I of Mycobacterium leprae.

The trisaccharide segment, O-(3,6-di-O-methyl-beta-D-glucopyranosyl)-(1----4)-O-(2,3-di-O-methyl- alpha-L-rhamnopyranosyl)-(1----2)-3-O-methyl-L-rhamnopyranose, of the Mycobacterium leprae-specific phenolic glycolipid I has been synthesized as its 8-(methoxycarbonyl)octyl glycoside and coupled to a carrier protein, to produce a leprosy-specific neoglycoprotein, the so-called natural trisaccharide-octyl-bovine serum albumin (NT-O-BSA). Special features of the synthetic strategy were the use of silver trifluoromethanesulfonate (triflate) to promote glycosylation, resulting in the rhamnobiose in high yield and absolute stereospecificity. The terminal 3,6-di-O-methyl-D-glucopyranosyl group was introduced after O-deallylation of the rhamnobiose. Removal of protecting groups yielded the trisaccharide hapten suitable for coupling to carrier protein. Poly(acrylamide)-gel electrophoresis of the neoglycoprotein demonstrated its purity, and subsequent immunoblotting with a monoclonal antibody directed to the terminal 3,6-di-O-methyl-beta-D-glucopyranosyl epitope of the native glycolipid demonstrated its antigenicity. Comparative serological testing in enzyme-linked immunosorbent assays of NT-O-BSA, the corresponding disaccharide-containing products, and another trisaccharide-containing neoglycoprotein, O-(3,6-di-O-methyl-beta-D-glucopyranosyl)-(1----4)-O-(2,3-di-O- methyl-alpha-L-rhamnopyranosyl)-(1----2)-(3-O-methyl-alpha-L-rhamnopy ran osyl)- (1----4')-oxy-(3-phenylpropanoyl)-BSA (NT-P-BSA) [Fujiwara et al., Agric. Biol. Chem., 51 (1987) 2539-2547] against sera from leprosy patients and control populations showed concordance; the presence of the innermost sugar did not contribute significantly to sensitivity or specificity. The di- and tri-saccharide-containing neoantigens, on account of ready availability and solubility, provide greater flexibility than the native glycolipid for the serodiagnosis of leprosy.

Antigens, Bacterial↗
PubMed1988

Further novel amido sugars within the glycopeptidolipid antigens of Mycobacterium avium.

The individual serovars of the Mycobacterium avium complex, a source of serious and persistent infections in individuals with underlying immune deficiencies, also present an extraordinary set of novel sugar epitopes as part of their type-specific glycopeptidolipid surface antigens. Californium desorption-mass spectrometry has been successfully applied to the holistic glycopeptidolipid antigen of M. avium serovar 12 and its per-O-acetyl derivative, to arrive at the following structure, of molecular mass 1876: (Sequence: see text). The pentasaccharide hapten, released as the tetraglycosyl alditol, was subjected to methylation analysis, absolute configurational analysis, 1H NMR and fast atom bombardment-mass spectrometry to arrive at the structure: 4-(2'-Hydroxy) propionamido-4,6-dideoxy-3-O-Me-Glcp (beta 1----3)-4-O-Me-L-Rhap (alpha 1----3)-L-Rhap (alpha 1----3)-L-Rhap (alpha 1----2)-6-deoxytalitol. Two-dimensional proton correlation spectroscopy was also applied to determine the configuration of the unique distal segment of the oligosaccharide unit. The significance of this structure in the context of the fully elucidated structures of the antigens from 12 of the 31-member M. avium complex is discussed.

Antigens, Bacterial↗