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Sircar S, Mohr R, Ristic C, Rao MB. Isosteric Heat of Adsorption: Theory and Experiment. J Phys Chem B 1999; 103:6539-6546. [DOI: 10.1021/jp9903817] [Citation(s) in RCA: 161] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Sircar S, Rao M, Golden T. Fractionation of air by zeolites. STUDIES IN SURFACE SCIENCE AND CATALYSIS 1999. [DOI: 10.1016/s0167-2991(99)80559-x] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
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Sircar S, Ruzindana-Umunyana A, Neugebauer W, Weber JM. Adenovirus endopeptidase and papain are inhibited by the same agents. Antiviral Res 1998; 40:45-51. [PMID: 9864045 DOI: 10.1016/s0166-3542(98)00040-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Adenoviruses encode a cysteine protease (AVP) which carries out highly specific cleavages on at least seven viral proteins and two cellular proteins. Virus infectivity is dependent on this function. The three-dimensional positions of the amino acids involved in catalysis display a striking similarity to those of papain, suggesting a similar catalytic mechanism. This similarity has prompted us to compare the effect of papain inhibitors on the two enzymes. AVP and papain activity was tested on a fluorescent peptide substrate as well as on metabolically labeled adenovirus (Ad2) precursor proteins. Hep2 cells infected with Ad2 were exposed to inhibitors and assayed for, (a) infectious virus, (b) in situ Ad2 protease activity, (c) physical particle production and their polypeptide composition. We found that in both substrate systems AVP was sensitive to the papain inhibitors benzamidoacetonitrile, acetamidoacetonitrile and N-methoxyphenylalanine glycylnitrile, and that the degree of sensitivity was influenced by the substrate. Unlike papain, AVP was relatively insensitive to E64. In ex vivo tests, Hep2 cells infected with Ad2 were exposed to inhibitors and assayed for, (a) infectious virus, (b) in situ Ad2 protease activity, (c) physical particle production and their polypeptide composition. A 4-fold reduction in virus titer was obtained when the inhibitors were added between 17 and 25 h after infection. Processing of precursor proteins was also inhibited yet the production of physical particles was only reduced 2-fold. These experiments show that papain inhibitors are also capable of inhibiting the adenovirus protease both in vitro and ex vivo, thus forging a possible link between structural similarity and functionality.
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Sircar S, Kansra U. Choice of cooking oils--myths and realities. JOURNAL OF THE INDIAN MEDICAL ASSOCIATION 1998; 96:304-7. [PMID: 10063298] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
In contrast to earlier epidemiologic studies showing a low prevalence of atherosclerotic heart disease (AHD) and type-2 dependent diabetes mellitus (Type-2 DM) in the Indian subcontinent, over the recent years, there has been an alarming increase in the prevalence of these diseases in Indians--both abroad and at home, attributable to increased dietary fat intake. Replacing the traditional cooking fats condemned to be atherogenic, with refined vegetable oils promoted as "heart-friendly" because of their polyunsaturated fatty acid (PUFA) content, unfortunately, has not been able to curtail this trend. Current data on dietary fats indicate that it is not just the presence of PUFA but the type of PUFA that is important--a high PUFA n-6 content and high n-6/n-3 ratio in dietary fats being atherogenic and diabetogenic. The newer "heart-friendly" oils like sunflower or safflower oils possess this undesirable PUFA content and there are numerous research data now available to indicate that the sole use or excess intake of these newer vegetable oils are actually detrimental to health and switching to a combination of different types of fats including the traditional cooking fats like ghee, coconut oil and mustard oil would actually reduce the risk of dyslipidaemias, AHD and Type-2 DM.
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Rynders RM, Rao MB, Sircar S. Isotope exchange technique for measurement of gas adsorption equilibria and kinetics. AIChE J 1997. [DOI: 10.1002/aic.690431009] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Sircar S, Taneja VA, Kansra U. ANA-negative SLE presenting with nephritis and oculomotor palsy--a case report. INDIAN J PATHOL MICR 1997; 40:539-42. [PMID: 9444868] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Most large series of patients with systemic lupus erythematosus (SLE) have revealed a very small group of patients who are persistently antinuclear antibody (ANA) negative with prominent dermatologic involvement but infrequent neurological and renal involvement. We present a very unusual case report of a young female with ANA-negative SLE presenting with lupus nephritis and oculomotor palsy without any dermatologic manifestations.
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Parrillo DJ, Thaeron C, Sircar S. Separation of bulk hydrogen sulfide–hydrogen mixtures by selective surface flow membrane. AIChE J 1997. [DOI: 10.1002/aic.690430910] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Naheiri T, Ludwig KA, Anand M, Rao MB, Sircar S. Scale-Up of Selective Surface Flow Membrane for Gas Separation. SEP SCI TECHNOL 1997. [DOI: 10.1080/01496399708004068] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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62
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Anand M, Langsam M, Rao M, Sircar S. Multicomponent gas separation by selective surface flow (SSF) and poly-trimethylsilylpropyne (PTMSP) membranes. J Memb Sci 1997. [DOI: 10.1016/s0376-7388(96)00186-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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63
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Diouri M, Girouard GS, Allen CM, Sircar S, Van Lier JE, Weber JM. New stimulation ligand of the adenovirus 2 protease. Virology 1996; 224:510-6. [PMID: 8874511 DOI: 10.1006/viro.1996.0557] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The catalytic activity of the adenovirus cysteine peptidase is increased by a specific 11-amino-acid peptide adduct (GVQSLKRRRCF, referred to as pVIc). To identify additional peptides which might bind and alter the activity of the protease, a cysteine-constrained random peptide phage library was screened. Of 29 different phages which were isolated, 7 contained the consensus sequence VEGGS. Despite a superficial similarity to the substrate cleavage site of the protease, the peptide was not digested by the enzyme. VEGGS and pVIc altered protease activity similarly without sharing sequence similarity. To similar degrees, pVIc and VEGGS (a) stimulated the activity of the recombinant protease, (b) had no effect on viral protease, (c) increased the fluorescence emission of tryptophan residues in the protease, suggesting a conformational change, and (d) inhibited wt virus infection, but rescued ts1 infection at the nonpermissive temperature. The experiments also suggest that once the protease has been stimulated by one peptide, the other peptide has no further activity on the recombinant adenovirus cysteine protease, suggesting that the two peptides bring about the same change on the protease via different binding sites.
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Sircar S, Taneja VA, Kansra U. Epidemiology and clinical presentation of abdominal tuberculosis--a retrospective study. JOURNAL OF THE INDIAN MEDICAL ASSOCIATION 1996; 94:342-4. [PMID: 9019081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The epidemiology and clinical presentation of abdominal tuberculosis were studied retrospectively in 298 adult cases admitted in Safdarjang Hospital, New Delhi over a 3-year period. These constituted 17% of the total number of admissions for tuberculosis. Age at presentation was variable with maximum cases in 21 to 40-year age group (58% of cases) with a mean age of 32.7 years. There was a slight female preponderance (57%). Sixty-three per cent were residing in urban areas. Pain abdomen, ascites and subacute intestinal obstruction were the commonest modes of presentation (34%, 30%, 28% respectively). Other clinical features included fever (21%), altered bowel habits (19%), weight loss (8%) and lump abdomen (6%). Acute intestinal obstruction and lower gastro-intestinal bleeding were uncommon (5% and 4% respectively). Co-existent pulmonary tuberculosis was seen in 16% cases. Histological evidence was available in 41% cases. Majority improved with conservative management with only 21% requiring surgical intervention. Mortality recorded was 11%.
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Abstract
The effect of a series of cysteine and serine protease inhibitors was tested on the growth of human adenovirus type 2 in tissue culture. In accordance with the nature of the adenovirus protease, only the cysteine protease inhibitors were effective in significantly reducing the production of infectious virus. Addition of the inhibitors to the medium 18 h after infection gave IC50 of 30, 40 and 80 nM with N-ethylmaleimide, leupeptin and E64c, respectively. Several lines of evidence suggest that inhibition of infectious virus formation operated through the inhibition of the viral protease rather than cellular toxicity: (a) the yield of physical particles declined only 4-5-fold, while that of infectious virus declined 3-7 orders of magnitude, (b) these particles contained unprocessed precursor proteins and (c) pulse-chase experiments showed that the inhibitors prevented the efficient processing of viral precursor proteins. We conclude that the cysteine protease inhibitors efficiently depress the formation of infectious adenovirus by inhibiting the viral protease.
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Rao M, Sircar S. Performance and pore characterization of nanoporous carbon membranes for gas separation. J Memb Sci 1996. [DOI: 10.1016/0376-7388(95)00241-3] [Citation(s) in RCA: 132] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Sircar S. R&D note: Data representation for binary and multicomponent gas adsorption equilibria. ADSORPTION 1996. [DOI: 10.1007/bf00879549] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Rancourt C, Keyvani-Amineh H, Sircar S, Labrecque P, Weber JM. Proline 137 is critical for adenovirus protease encapsidation and activation but not enzyme activity. Virology 1995; 209:167-73. [PMID: 7747466 DOI: 10.1006/viro.1995.1240] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Infection with the adenovirus type 2 ts1 mutant at the nonpermissive temperature resulted in the production of noninfectious virions. This has been ascribed to the P137L mutation in the virus-encoded cysteine protease which causes a defect in protease activity. Here we have examined the ts1 defect in detail as a means of learning more about the viral protease. The ts1 protease accumulated in the nucleus normally and was found associated with incomplete particles as was the case with wt. This enzyme was active in both wt and ts1 incomplete particles produced at 39 degrees (ts1-39 TCs), provided they were dissociated with 4 M urea. While the wt protease was packaged into complete particles, the ts1-39 particles were totally devoid of protease. This defect was nearly completely corrected by addition of the 11-residue activating peptide PVIc (GVQSLKRRRCF) to the medium late in infection. Rescue of ts1 occurred via restoration of enzyme activity and packaging of the ts1 enzyme into complete virions. Recombinant ts1 enzyme was not temperature sensitive. The P137L mutation responsible for the ts1 defect appeared therefore to be an in vivo phenotype involving apparently linked events of protease packaging and activation mediated by the PVI protein.
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Sircar S, Hanley BF. Production of oxygen enriched air by rapid pressure swing adsorption. ADSORPTION 1995. [DOI: 10.1007/bf00707354] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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71
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Golden TC, Sircar S. Equilibrium and kinetics of adsorption of Freon-12 at infinite dilution. AIChE J 1994. [DOI: 10.1002/aic.690400604] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Weber JM, Sircar S, Bégin ME. Greater sensitivity of human multidrug-resistant (mdr) cancer cells to polyunsaturated fatty acids than their non-mdr counterparts. J Natl Cancer Inst 1994; 86:638-9. [PMID: 8145280 DOI: 10.1093/jnci/86.8.638] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
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Rao M, Sircar S. Nanoporous carbon membranes for separation of gas mixtures by selective surface flow. J Memb Sci 1993. [DOI: 10.1016/0376-7388(93)85279-6] [Citation(s) in RCA: 191] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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75
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Rao MB, Sircar S. Concentration-Thermal Swing Adsorption Process for Separation of Bulk Liquid Mixtures. SEP SCI TECHNOL 1993. [DOI: 10.1080/01496399308029244] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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