Search PubMed⌕ Search

Biomedical subjects

D Chatterjee

Publications and source records attributed to D Chatterjee.

At least 91 records · Page 5Linked to original sources
PubMed1993

The human platelet dense granule: serotonin uptake, tetrabenazine binding, phospholipid and ganglioside profiles.

The functioning and composition of human platelet dense granules were studied using granules purified by Percoll fractionation. Reserpine-blockable serotonin (5-HT) uptake by the dense granule fraction was characterized and also demonstrated in the crude membrane fraction. Tetrabenazine (TBZ)-displaceable [3H]ketanserin binding was used to label the granular 5-HT transporter. Scatchard analyses, Hill plots, displacement curves, and binding kinetics indicated that TBZ-displaceable [3H]ketanserin binding labeled a site similar to that previously reported for chromaffin granules and synaptic vesicles. Analysis of phospholipid profiles in platelet fractions revealed that most platelet lysolecithin was associated with the dense granule fraction. Ganglioside analysis indicated that the predominant platelet ganglioside, GM3, was highly enriched in the dense granule fraction. The data lend further support to the idea that the 5-HT transporter complex is similar in platelet dense granules, chromaffin granules, and synaptic vesicles. However, the ganglioside and phospholipid findings clearly distinguish the types of storage sites and raise questions concerning the functional roles of dense granule GM3 and lysolecithin.

Animals↗
PubMed1993

Protection of bone-marrow granulocyte-macrophage colony-forming units in mice bearing in vivo alkylating-agent-resistant EMT-6 tumors.

The survival of bone-marrow granulocyte-macrophage colony-forming units (CFU-GM), an alkylating-agent-sensitive normal tissue, was assessed in mice bearing the EMT-6 parental tumor or the in vivo resistant EMT-6/CDDP, EMT-6/CTX, EMT-6/Thio, and EMT-6/Carbo tumors. The survival pattern of the bone-marrow CFU-GM recapitulated the survival of the tumor cells, mimicking the development of resistance and reversion to sensitivity upon removal of the selection pressure for each of the four alkylating agents. When the EMT-6 parental tumor was implanted in the opposite hind limb of animals bearing the EMT-6/CDDP or EMT-6/CTX tumor, the survival of the parental tumor cells after treatment of the animals with the appropriate antitumor alkylating agent was enhanced. The EMT-6/CDDP tumor was cross-resistant to CTX and high-dose L-PAM, whereas the EMT-6/CTX tumor was somewhat resistant to CDDP and markedly sensitive to VP-16. In each case, the survival pattern of the bone-marrow CFU-GM reflected the survival of the tumor cells. These results indicate that the presence of an alkylating-agent-resistant tumor in an animal can affect the drug response of tissues distal to that tumor.

Alkylating Agents↗
PubMed1993

Structural definition of the non-reducing termini of mannose-capped LAM from Mycobacterium tuberculosis through selective enzymatic degradation and fast atom bombardment-mass spectrometry.

The application of extracellular arabinases from a Cellulomonas sp. and fast atom bombardment-mass spectrometry (FAB-MS) provided new insight into the structure of lipoarabinomannan (LAM) of Mycobacterium tuberculosis, a key molecule in the pathogenesis and physiology of the tubercle bacillus. Previously, the non-reducing arabinan ends of LAM from the virulent (Erdman) strain of M. tuberculosis were shown to be 'capped' by short (alpha 1-->2)-linked mannopyranose (Manp)-containing oligosaccharides, a product called ManLAM. The structural relationship between these Manp units and the underlying arabinofuranose (Araf)-containing arabinan was examined by digesting ManLAM from M.tuberculosis Erdman with the Cellulomonas enzyme, resolving fragments by various means and subjecting the derivatized oligoglycosylalditols to FAB-MS. The sequences Manp2Araf4, Manp3Araf4 and Manp1-6Araf6 were recognized as the major terminal motifs. Upon complete structural definition, all of the Ara6-containing products were shown to be based on a 3,5-linked branched Araf unit, whereas those containing Ara4 were linear. Minor non-mannosylated terminal arrangements containing Ara4-6, branched, linear and cyclical, were also recognized. In addition, the mannan 'core' of ManLAM was isolated from enzyme digests and shown to contain segments of the phosphatidylinositol anchor and a 'stub' of the arabinan side-chain in the form of a 'linker' alpha-Araf-(1-->5)-Araf unit attached to C-2, apparently of the penultimate 2,6-linked Manp residue. The structural unravelling of this complex molecule further substantiates the case for structural and biological similarities to the enterobacterial lipopolysaccharides/lipoglycans and other important 'capped' lipooligomers such as the lipooligosaccharides of Neisseria species and the lipophosphoglycan of Leishmania promastigotes.

Carbohydrate Sequence↗
PubMed1993

Structure and antigenicity of lipoarabinomannan from Mycobacterium bovis BCG.

Lipoarabinomannan (LAM), a major lipoglycan of the mycobacterial cell envelope, was previously recognized as existing in two major forms: LAM with arabinofuranosyl (Araf)-containing termini (AraLAM) and a mannose-capped version (ManLAM) in which the majority of these termini are modified by additional mannose residues. Since ManLAM was first recognized in the virulent (Erdman) strain of Mycobacterium tuberculosis and the noncapped version in a rapidly growing, attenuated, H37Ra strain, it was thought that mannose capping may be a key factor in virulence. In the present study, LAM from M. bovis BCG was isolated and the non-reducing termini sequenced through differential O-alkylation, partial depolymerization and gas chromatography-mass spectrometric analyses of fragments. LAM from M. bovis BCG contains a short mannan backbone, highly branched arabinofuranosyl-containing side chains and several mannosyl residues capping the non-reducing termini of these side chains. Thus, LAM from M. bovis BCG is of the ManLAM type, showing no major structural differences at the non-reducing ends from the M. tuberculosis Erdman product. This observation led us to examine the earlier strain and to conclude that it showed little resemblance to conventional strains of M. tuberculosis. Thus, the absence of mannose caps may be more a feature of rapid growth than of avirulence. These results demonstrate that the relationship between mannose capping and disease induction is not a simple one. However, use of a panel of LAM-specific monoclonal antibodies showed antigenic differences between the BCG and the Erdman products, suggesting the presence of features specific to the different strains and pointing to LAM as a molecule within which further species and strain variations reside.

Antigens, Bacterial↗
PubMed1993

Destruction of phagocytosis-suppressing activity of aflatoxin B1 by ozone.

The impact of ozone on the immunity-impairing activity of aflatoxin B1 (AFB1) was studied. Phagocytosis by rat peritoneal macrophages, which was found to be suppressed in the presence of AFB1, remained unimpaired when the applied AFB1 was pretreated with ozone (1.2 mg l-1) for 6 min at a flow rate of 40 ml min-1. Hence, application of ozone on AFB1-contaminated foodcrops seems to be a promising preventive measure against any adverse immunological disorder in consumers.

Aflatoxin B1↗
PubMed1993

Proliferation of nontransformed cells is inhibited by adenosine metabolite of but not by parental 8-Cl-cyclic AMP.

In this study we evaluated the regulatory effect of 8-Cl-cyclic AMP (cAMP) on the proliferation of nontransformed cells. Our data indicate that similar to the reported inhibitory effect of 8-Cl-cAMP on the proliferation of Molt-4 lymphoma cells, the inhibitory effect of 8-Cl-cAMP on the proliferation of nontransformed fibroblast, myoblast and endothelial cells was dependent on serum or cyclic nucleotide phosphodiesterases and other nucleotide phosphatases. This suggested that the metabolism of 8-Cl-cAMP was required for the inhibition of cell proliferation. In addition, this serum-dependent inhibitory effect of 8-Cl-cAMP was antagonized by the presence of exogenous adenosine deaminase, suggesting that 8-Cl-adenosine was responsible for mediating the serum-dependent inhibitory effect of 8-Cl-cAMP on these cells. This idea was supported further by the ability of 8-Cl-adenosine to duplicate the inhibitory effect of 8-Cl-cAMP on cell proliferation in defined medium.

2-Chloroadenosine↗
PubMed1992

Structures of the glycopeptidolipid antigens of serovars 25 and 26 of the Mycobacterium avium serocomplex, synthesis of allyl glycosides of the outer disaccharide units and serology of the derived neoglycoproteins.

The pentasaccharide hapten released from the glycopeptidolipid (GPL) antigen of M. avium serovar 26 has been characterized as O-(2,4-di-O-methyl-alpha-L-fucopyranosyl)-(1-->4)- O-beta-D-glucopyranosyluronic acid-(1-->4)-O-(2-O-methyl-alpha-L-fucopyranosyl)-(1-->3)-alpha-L- rhamnopyranosyl-(1-->2)-6-deoxy-L-talose. The allyl glycosides of the outer glycosyl and glycobiosyl units of this hapten have been synthesized, the latter by a route involving oxidation of the corresponding D-glucopyranose derivative. Conjugation of allyl glycosides to protein by ozonolysis and reductive coupling afforded neoantigens (neo 26-1 and 26-2), both of which interacted with antibodies to M. avium serovar 26. The terminal sugar residue of the pentasaccharide hapten of the serovar 25 GPL had been shown to have the galacto configuration on the basis of 1H-13C NMR correlation spectroscopy, but absolute configurational assignment for the sugar awaited the synthesis, as for neo 26, of two glycobiosyl NGPs bearing the terminal sugar in the D and L enantiomeric forms, respectively. Only the glycobiosyl NGP bearing the terminal sugar as the D-enantiomer interacted with antibodies to M. avium serovar 25, thus providing evidence for the absolute configuration of the sugar, and showing that the complete oligosaccharide hapten has the structure, O-(4-acetamido-4,6-dideoxy-2-O-methyl-alpha-D- galactopyranosyl)-(1-->4)-O-beta-D-glucopyranosyluronic acid-(1-->4)-O-(2-O-methyl-alpha-L-fucopyranosyl)-(1-->3)-O-alpha-L- rhamnopyranosyl-(1-->2)-6-deoxy-L-talose.

Allyl Compounds↗
PubMed1992

Sensitivity to vanadate and isoforms of subunits A and B distinguish the osteoclast proton pump from other vacuolar H+ ATPases.

Analysis of proton (H+) transport by inside-out vesicles derived from highly purified chicken osteoclast (OC) membranes has revealed the presence of a newly discovered type of vacuolar H+ ATPase (V-ATPase). Unlike vesicles derived from any other cell type or organelle, H+ transport in OC-derived vesicles is sensitive to V-ATPase inhibitors (N-ethylmaleimide and Bafilomycin A1) and vanadate (IC50, 100 microM), an inhibitor previously found to affect only P-type ATPases. The OC H+ ATPase contains several V-like subunits (115, 39, and 16 kDa) but subunits A and B of the catalytic domain of the enzyme differ from that of other V-ATPases. In OCs, subunit A has a mass of 63 kDa instead of the 67-70 kDa expressed in monocytes, macrophages, and kidney microsomes, which contain a vanadate-insensitive H+ ATPase. Moreover, two types of 57- to 60-kDa B subunits are also found: one is expressed predominantly in OCs and the other is expressed in kidney microsomes. The OC H+ pump may therefore constitute a class of H+ ATPase with a unique pharmacology and specific isoforms of two subunits in the catalytic portion of the enzyme. This H+ ATPase is involved in resorption of bone and may be expressed in a cell-specific manner, thereby opening possibilities for therapeutic intervention.

Animals↗
PubMed1992

Cytokine production induced by Mycobacterium tuberculosis lipoarabinomannan. Relationship to chemical structure.

Lipoarabinomannan (LAM), a major cell wall component of Mycobacterium tuberculosis, exhibits a wide spectrum of immunoregulatory effects. To identify cytokines produced by human PBMC in response to LAM, we used PCR amplification to detect cytokine mRNA. LAM-induced transcription of mRNA for cytokines characteristically produced by macrophages, including TNF, granulocyte-macrophage-CSF, IL-1 alpha, IL-1 beta, IL-6, IL-8, and IL-10. In contrast, LAM did not induce transcription of mRNA for cytokines produced predominantly by lymphocytes, such as lymphotoxin, IFN-gamma, IL-2, IL-3, or IL-4. Measurement of concentrations of TNF, granulocyte-macrophage-CSF, IL-6, IL-10, IFN-gamma, IL-2, and IL-4 in cell culture supernatants indicated that cytokine release correlated with mRNA patterns. Lipomannan (LM) and phosphatidylinositol mannosides (PIM) are simpler versions of LAM. LM lacks arabinan, whereas PIM lacks both arabinan and most mannan residues. LAM, LM, and PIM induced transcription of cytokine mRNA, elicited cytokine production, and suppressed Ag-induced T cell proliferation, indicating that most of the biologic activity of LAM was associated with the phosphatidylinositol end of the molecule. In support of this conclusion, deacylation of LAM abrogated its capacity to induce cytokine production and suppress Ag-induced proliferation. The production of macrophage-derived cytokines induced by LAM may mediate clinical manifestations of tuberculosis such as fever, weight loss, and tissue necrosis, as well as immunoregulatory effects such as inhibition of Ag-induced proliferation and hyperglobulinemia.

Adult↗
PubMed1992

Differentiation of Neuro-2a neuroblastoma cells by an antibody to GM3 ganglioside.

A monoclonal antibody against GM3 ganglioside (GM3Ab) was found to trigger differentiation of Neuro-2a cells in culture. The differentiation of Neuro-2a cells by GM3Ab was accompanied by increased levels of intracellular serotonin and amino acid neurotransmitters viz. aspartate, glutamate, glutamine, glycine and taurine. Further study indicated that the increase in the serotonin level was not due to a higher rate of serotonin synthesis but rather to a higher rate of active transport of serotonin from the medium. Studies on the cell surface gangliosides revealed that unlike the proliferating cells, the GM3Ab-mediated differentiated cells contained higher gangliosides in addition to GM3 and GM2 gangliosides. Analysis of total cellular proteins indicated the appearance of a 25 kDa protein, pI 5.4, in the GM3Ab-treated cells--a small amount of this protein was observed in dibutyryl cAMP (Bt2cAMP)-treated cells, however, the protein was totally absent in the 5-bromo-2'-deoxyuridine (BrdU)-treated cells. Investigation of the mode of action of GM3Ab indicated that the cellular differentiation was due to increased cAMP accumulation resulting from an increase in the adenylate cyclase activity. Further studies with different agents affecting protein kinase C (PKC) activity and direct assay of PKC ruled out the possibility that GM3Ab mediated its effect via PKC. This GM3Ab-induced differentiation could be inhibited by protein kinase A (PKA) inhibitor, H8, but could not be inhibited by sphingosine, an inhibitor of PKC. Pertussis toxin could mimic the effect of GM3Ab, suggesting that GM3Ab caused the elevation in the adenylate cyclase activity by reducing the Gi-protein inhibition of the adenylate cyclase. The data suggests that GM3Ab, after interaction with cell surface GM3, elevated intracellular cAMP level by withdrawing the inhibitory effect of some undefined factor(s) present in culture medium which normally keeps adenylate cyclase activity low through activation of Gi-protein.

Amino Acids↗
PubMed1992

Lipoarabinomannan. Multiglycosylated form of the mycobacterial mannosylphosphatidylinositols.

The lipopolysaccharides of mycobacteria, lipoarabinomannan (LAM) and lipomannan (LM), of key importance in host-pathogen interaction, were recently shown to contain a phosphatidylinositol "anchoring domain." We now have established that LAM and LM are based on the phosphatidylinositol mannosides, the characteristic glycophospholipids of mycobacteria. Digestion of the arabinose-free LM with an endo-alpha 1----6-mannosidase yielded evidence for the presence of the 1-(sn-glycerol-3-phospho)-D-myo-inositol-2,6-bis-alpha-D-mannopyranoside unit, indistinguishable from that derived from phosphatidylinositol dimannoside. This same inositol substitution pattern was shown to be present in LAM by methylation analysis before and after dephosphorylation. Positions C-2 and C-6 of the inositol unit of LAM are occupied by mannosyl residues and C-1 by a phosphoryl group. Partial acid hydrolysis of per-O-methylated LAM and comparison by gas chromatography-mass spectrometry of the resulting derivatized oligosaccharides with like products from phosphatidylinositol hexamannoside demonstrated that the C-6 of inositol is the point of attachment of the mannan core of LAM, which consists of an alpha 1----6-linked backbone with considerable alpha-1----2 side chains. Thus, a structural and presumably biosynthetic relationship is established between some of the membranous mannosylphosphatidylinositols described some 25 years ago and the newly emerging, biologically active lipopolysaccharides of mycobacteria.

Carbohydrate Conformation↗
PubMed1992

Lipoarabinomannan of Mycobacterium tuberculosis. Capping with mannosyl residues in some strains.

Previously we had demonstrated that the termini of the arabinan component of mycobacterial cell wall arabinogalactan, the site of mycolic acid location, consists mostly of clusters of a pentaarabinofuranoside, [beta-D-Araf-(1----2)-alpha-D-Araf-(1----]2----(3 and 5)-alpha-D-Araf. Subsequently, the same arrangement was shown to dominate the non-reducing ends of lipoarabinomannan (LAM), a key component in the interaction of mycobacteria with host cell. Accordingly, we had proposed that mycobacteria universally elaborate the same Araf-containing motifs in two settings for different pathophysiological purposes. However, we now report that the termini of LAM from the virulent, Erdman, strain of Mycobacterium tuberculosis, unlike those from the attenuated H37Ra strain, are extensively capped with mannosyl (Manp) residues, either a single alpha-D-Manp, a dimannoside (alpha-D-Manp-(1----2)-alpha-D-Manp), or a trimannoside (alpha-D-Manp-(1----2)-alpha-D-Manp-(1----2)-alpha-D-Manp ). The use of monoclonal antibodies demonstrates a clear difference in the antigenicity of the basic and mannose-capped LAM. The possibility that these structures are a factor in the virulence of some strains of M. tuberculosis and represent an example of carbohydrate mimicry in mycobacterial infections is discussed.

Carbohydrate Conformation↗
PubMed1992

Posttranscriptional regulation of c-myc proto-oncogene expression and growth inhibition by recombinant human interferon-beta ser17 in a human colon carcinoma cell line.

Recombinant human interferon-beta ser17 (IFN-beta ser17), a cytokine that exhibits both antiviral and antiproliferative activity against a wide variety of cell types, causes a time- and dose-dependent inhibition of monolayer growth and of the expression of the c-myc proto-oncogene in DLD-1 Clone A human colon-carcinoma cells. The suppression of c-myc expression mediated by IFN-beta ser17 is due to a posttranscriptional destabilization of c-myc mRNA rather than to an inhibition of c-myc mRNA transcription. There is evidence suggesting that the selective reduction in the half-life of c-myc mRNA in IFN-beta ser17-treated cells occurs through an increase in the activity of the 2',5'-oligoadenylate synthetase/RNase L [2',5'-oligo (A) synthetase] pathway in DLD-1 Clone A cells. Cotreatment of these cells with IFN-beta ser17 and the anticancer agent N-methylformamide leads to the partial abrogation of 2',5'-oligo (A) synthetase activity and the stabilization of c-myc mRNA. These findings suggest that there is a correlation between the IFN-beta ser17-mediated suppression of c-myc expression and the induction of 2',5'-oligo (A) synthetase activity in DLD-1 clone A cells.

2',5'-Oligoadenylate Synthetase↗
PubMed1992

Thyroidal influence on the cell surface GM1 of granule cells: its significance in cell migration during rat brain development.

1. No difference was observed in the in vitro growing ability of granule cells isolated from hypothyroid or normal rat brain. When granule cells were taken from hypothyroid rat brain and grown in normal culture medium containing 10% fetal calf serum, they behaved similarly to the granule cells obtained from normal rat brain. 2. In both cases there were progressive losses of in vitro growing ability of the granule cells with the age of the animal and it became impossible to grow them when derived from 21 days or older animals. 3. A marked decrease in cell surface GM1 was observed when the cells were maintained under thyroid hormone-deficient conditions in culture. 4. Anti-GM1 antibody was found to inhibit significantly the migration of granule cells along the astrocyte fibers. 5. These results indicate that GM1 has an important role in thyroid hormone-dependent postnatal brain maturation in rat.

Age Factors↗
PubMed1992

Osteoclasts express high levels of pp60c-src in association with intracellular membranes.

Deletion of the c-src gene in transgenic mice by homologous recombination leads to osteopetrosis, a skeletal defect characterized by markedly deficient bone resorption (Soriano, P., C. Montgomery, R. Geske, and A. Bradley. 1991. Cell. 64:693-702), demonstrating a critical functional role of pp60c-src in osteoclast activity. Since decreased bone resorption could result from a defect either within the osteoclast or within other cells present in its environment, indirectly affecting osteoclast functions, we determined which cell(s) in bone expressed high levels of pp60c-src Measuring pp60c-src protein and kinase activities in osteoclasts and immunolocalizing pp60c-src in bone, we find that expression of pp60c-src is nearly as high in osteoclasts as in brain and platelets. In contrast, other bone cells contain only very low levels of the protein. In addition, expression of the c-src gene product increases when bone marrow cells are induced to express an osteoclast-like phenotype by 1,25-dihydroxy-vitamin D3, further suggesting that high expression of pp60c-src is part of the osteoclast phenotype. Three other src-like kinases, c-fyn, c-yes, and c-lyn, are also expressed in osteoclasts at ratios to pp60c-src similar to what is found in platelets. These src-related proteins do not, however, compensate for the absence of pp60c-src in the src- mice, thereby suggesting that pp60c-src may have a specific function in osteoclasts. Although further work is necessary to elucidate what the critical role of pp60c-src in osteoclasts is, our observation that the protein is associated mostly with the membranes of intracellular organelles suggests the possibility that this role might be at least in part related to the targeting or fusion of membrane vesicles.

Animals↗