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Pearce RE, McIntyre CJ, Madan A, Sanzgiri U, Draper AJ, Bullock PL, Cook DC, Burton LA, Latham J, Nevins C, Parkinson A. Effects of freezing, thawing, and storing human liver microsomes on cytochrome P450 activity. Arch Biochem Biophys 1996; 331:145-69. [PMID: 8660694 DOI: 10.1006/abbi.1996.0294] [Citation(s) in RCA: 168] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The stability of cytochrome P450 enzymes, cytochrome b5, and NADPH-cytochrome c reductase was examined in (A) human liver samples frozen in liquid nitrogen and stored at -80 degrees C, (B) human liver microsomes suspended in 250 mM sucrose and stored at -80 degrees C, and (C) human liver microsomes subjected to as many as 10 cycles of thawing and freezing. In study A, microsomes from five human livers were prepared from fresh (unfrozen) tissue and from tissue that was stored frozen at -80 degrees C for 1, 2, 4, or 6 months. The apparent concentration of cytochromes P450 and b5 and the activity of NADPH-cytochrome c reductase decreased 20-40% as a result of freezing the liver, regardless of whether the liver was stored for 1 or 6 months. Similar decreases were observed in the activities of cytochrome P450 enzymes belonging to several gene families, namely CYP1A2 (7-ethoxyresorufin O-dealkylation and caffeine N3-demethylation), CYP2A6 (coumarin 7-hydroxylation), CYP2C9 (tolbutamide methylhydroxylation), CYP2C19 (S-mephenytoin 4'- hydroxylation), CYP2D6 (dextromethorphan O-de-methylation), CYP2E1 (chlorzoxazone 6-hydroxylation), CYP3A4solidus5 (testosterone 6beta-hydroxylation), and CYP4A9solidus11 (lauric acid 12-hydroxylation). Freezing human liver did not convert cytochrome P450 to its inactive form, cytochrome P420, but it increased the contamination of liver microsomes with hemoglobin or other heme-containing proteins, which resulted in a uniform decrease in the specific activity of cytochromes P450 and b5 and in the specific activity of all P450 enzymes. In study B, the concentration of cytochromes P450 and b5, the activity of NADPH-cytochrome c reductase, and the activity of individual cytochrome P450 enzymes were determined in 10 samples of human liver microsomes stored at -80 degrees C for approximately 0, 1, or 2 years. The sample-to-sample variation in the concentration and activity of cytochrome P450, cytochrome b5, and NADPH-cytochrome c reductase was nominally affected by long-term storage of human liver microsomes at -80 degrees C, indicating there was no differential loss of cytochrome P450 activity, cytochrome b5 concentration, or NADPH-cytochrome c reductase activity. In study C, microsomes from a pool of human livers were subjected to 1, 2, 3, 5, 7, or 10 cycles of freezing at -80 degrees C followed by thawing at room temperature. Freezing/thawing liver microsomes for up to 10 cycles did not convert cytochrome P450 to P420, nor did it cause significant loss of CYP1A2, CYP2A6, CYP2C9, CYP2C19, CYP2D6, CYP2E1, CYP3A4/5, or CYP4A9/11 activity. Overall, these results suggest that our current methods for storing and processing human liver are well suited to preserving microsomal P450 enzyme activity.
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Menke DM, Tiemann M, Camoriano JK, Chang SF, Madan A, Chow M, Habermann TM, Parwaresch R. Diagnosis of Castleman's disease by identification of an immunophenotypically aberrant population of mantle zone B lymphocytes in paraffin-embedded lymph node biopsies. Am J Clin Pathol 1996; 105:268-76. [PMID: 8602606 DOI: 10.1093/ajcp/105.3.268] [Citation(s) in RCA: 82] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Castleman's disease (CD) is characterized by lymph node enlargement due to hyperplasia of abnormal lymphoid follicles and paracortical lymphocytic hyaline vascular (HV) stroma or plasmacytosis (PC). The lymphoid follicles in CD show involuted germinal centers and prominent mantle zone lymphocytes. Ninety-seven cases clinically suspected to be CD were analyzed according to conventional histologic criteria established by Castleman and Keller for diagnosis. Twenty-two cases were excluded as nonspecific hyperplasia (12); Hodgkin's and non-Hodgkin's lymphoma (9); and multiple myeloma involving lymph node paracortex (1). The 75 remaining cases, consisting of 51 cases of CD and 24 with altered follicles or paracortex suggestive of CD, were further analyzed immunohistologically for changes in follicular dendritic reticulum cells (FDRC) using the monoclonal antibody Ki-M4p, for germinal center proliferation with Ki-S5, for mantle zone immunophenotype with Ki-B3 and Ki-B5, for paracortical plasmacytoid monocytes with Ki-M1p, and for plasma cell clonality by applying antibodies to kappa and lambda immunoglobulin light chains. Lymph nodes showing nonspecific follicular and paracortical hyperplasia were included as controls. Hyaline vascular CD and plasma cell CD showed enlarged, polyploid FDRC with prominent nucleoli, decreased germinal center proliferation, and mantle zone populations of immunophenotypically aberrant, Ki-B3-negative B lymphocytes. Thirty-seven percent of hyaline vascular CD and plasma cell CD contained plasmacytoid monocytes, and 15% showed interstitial areas of lambda predominant plasma cells. Plasmacytoid monocytes were common in hyaline vascular CD but rare in plasma cell CD. Cases suspected to be CD that demonstrated a mantle zone population of Ki-B3-negative B lymphocytes had clinical finding of POEMS (polyneuropathy, organomegaly, endocrinopathy, monoclonal paraprotein, and skin changes or sclerotic bone lesions) syndrome and were reclassified as hyaline vascular CD, plasma cell CD, and mantle zone CD with an aberrant mantle zone immunophenotype only (lacking follicular center and paracortical histologic or immunohistologic abnormalities). Immunohistochemistry was valuable for identification of dysplastic FDRC, decreased germinal center proliferation, and plasmacytoid monocytes. In addition, immunohistochemistry was essential for detection of plasma cell clonality, an aberrant mantle zone immunophenotype, and mantle-zone-restricted CD that was devoid of diagnostic alterations of germinal center or paracortex.
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Khalil A, Gupta S, Madan A, Venkatesan M. Lipid profile norms in Indian children. Indian Pediatr 1995; 32:1177-80. [PMID: 8772866] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
OBJECTIVES To evaluate the lipid parameters in normal Indian children. DESIGN Cross-sectional. SETTING Hospital based. METHODS 410 children (siblings of hospitalized pediatric cases) between 3-12 years were evaluated for total plasma cholesterol (TC), triglycerides (TG) and high density lipoprotein cholesterol (HDL-C). The low density lipoprotein cholesterol (LDL-C) levels were derived from the above parameters using Fredrickson-Friedwald formula. RESULTS No significant difference was found between the sexes in any of the lipid parameters studied. The mean values were: TC-134.5 mg/ dl, TG-91.1 mg/dl, HDL-C-34.15 mg/dl and LDL-C-80.1 mg/dl. The suggested cut off limits for these parameters were 190 mg/dl, 150 mg/dl, 20 mg/dl and 130 mg/d respectively. CONCLUSIONS Lipid profile norms and cut off levels to define abnormalities for Indian children were recommended. The HDL-C levels were lower than western data.
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Madan A, Parkinson A, Faiman MD. Identification of the human and rat P450 enzymes responsible for the sulfoxidation of S-methyl N,N-diethylthiolcarbamate (DETC-ME). The terminal step in the bioactivation of disulfiram. Drug Metab Dispos 1995; 23:1153-62. [PMID: 8654205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The present study investigated the role of rat and human cytochrome P450 enzymes in the sulfoxidation of S-methyl N,N-diethylthiolcarbamate (DETC-Me) to S-methyl N,N-diathylthiolcarbamate sulfoxide (DETC-Me sulfoxide), the putative active metabolite of disulfiram. DETC-Me sulfoxidation by microsomes from male and female rats treated with various cytochrome P450-enzyme inducers suggested that multiple enzymes can catalyze this reaction, and these include, CYP1A1/2, CYP2B1/2, and CYP3A1/2. All cDNA-expressed human cytochrome P450 enzymes examined catalyzed the sulfoxidation of DETC-Me. The turnover rates (min-1) of DETC-Me sulfoxidation by the cDNA-expressed cytochrome P450 enzymes ranked as follows: CYP3A4 > CYP2A6 = CYP2C9 > CYP1A2 > CYP2B6 = CYP2E1 > CYP1A1 > CYP2D6. Interestingly, CYP3A4 ranked first or last, depending on whether or not additional NADPH-cytochrome P450 reductase was coexpressed in the lymphoblastoid cells. This complicated estimates of the contribution of CYP3A4 to DETC-Me sulfoxidation by human liver microsomes. The sample-to-sample variation in DETC-Me sulfoxidation by bank of human liver microsomes (N=13) correlated highly with coumarin 7-hydroxylation (r=0.88) and testosterone 6beta-hydroxylation (r=0.90), suggesting that CYP2A6 and CYP3A4/5 contribute to the sulfoxidation of DETC-Me by human liver microsomes. Although, chlorzoxazone 6-hydroxylation (a marker for CYP2E1) correlated poorly with DETC-Me sulfoxidation, the correlation improved from r=0.07 to r=0.44 when DETC-Me sulfoxidation was studied in the presence of the CYP2A6 inhibitor, coumarin. Similarly, when DETC-Me sulfoxidation was studied in the presence of diethyldithiocarbamate (DDTC), the inhibited DETC-Me sulfoxidase activity correlated better (r=0.50) with chlorzoxazone 6-hydroxylase, compared with DETC-Me sulfoxidase activity in the absence of DDTC (r=0.09). Polyclonal antibodies against CYP2E1 caused a modest inhibition (30%) of DETC-Me sulfoxidation by human liver microsomes. Anti-CYP3A1 antibodies completely inhibited DETC-Me sulfoxidation by cDNA-expressed CYP3A4. Under similar conditions, DETC-Me sulfoxidation by human liver microsomes was only partially inhibited by anti-CYP3A1 antibodies. Although studies with the rat and cDNA-expressed cytochrome P450 enzymes suggested that CYP1A2 contributed to DETC-Me sulfoxidation, this reaction was not inhibited by either furafylline ( a mechanism-based inhibitor of CYP1A2) or antibodies against CYP1A1/2. A significant role for CYP2C9 was excluded by the inability of sulfaphenazole to inhibit the sulfoxidation of DETC-Me by human liver microsomes. Collectively, these data suggest that multiple cytochrome P450 enzymes can catalyze the sulfoxidation of DETC-Me. In human liver microsomes the CYP2A6, CYP2E1, and CYP3A4/5 all contribute significantly to the sulfoxidation of DETC-Me. It is interesting to note that DDTC, the reduced metabolite of disulfiram, is known to inhibit these same enzymes. The ability of DDTC to block the formation of DETC-Me sulfoxide may explain why the dose of disulfiram required to produce a disulfiram-ethanol reaction in alcoholics is so variable and often inadequate.
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Madan A, Radha PK, Hosur RV, Padhy LC. Bacterial expression, characterization and DNA binding studies on Drosophila melanogaster c-Myb DNA-binding protein. EUROPEAN JOURNAL OF BIOCHEMISTRY 1995; 232:150-8. [PMID: 7556144 DOI: 10.1111/j.1432-1033.1995.tb20793.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The Drosophila Myb homologue retains an evolutionarily conserved typical sequence of three imperfect tandem tryptophan repeat units (R1-R2-R3) of 51-53 amino acids towards its N-terminus as its presumptive DNA binding domain. Using PCR amplification and the T7 expression vector pET 11d, we have overproduced this tryptophan repeat domain of Drosophila Myb in Escherichia coli and the protein has been purified. Circular dichroic measurements indicate that the protein has a high helical component (58.6%) in its overall structure. The protein is found to recognize the same cognate target sequence TAACGG, as recognized by the vertebrate proteins. The DNA binding properties of the protein have been investigated in detail by fluorescence spectroscopy taking advantage of the large number of tryptophan residues present in the protein. The fluorescence of the native Drosophila R123 was quenched when synthetic duplex DNA oligomers were added to the protein. The oligomers containing specific Myb target sites quenched the protein fluorescence to a greater extent than the non-specific DNA. Binding constants of the protein to the targets were also length dependent for smaller oligomers. Experiments with the collisional quencher acrylamide and cysteine modification reagent indicated that the specific and non-specific target sequences interact with the protein differently. In the former case both the buried and the exposed tryptophan residues were affected by DNA binding whereas in the latter only the solvent-exposed residues were involved.
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Singh S, Madan A, Hosur RV. Conformational dynamism in d-(GAATTCCGTTATT) containing the complementary Myb responsive element d-CCGTTA: NMR and MD investigations. INDIAN JOURNAL OF BIOCHEMISTRY & BIOPHYSICS 1995; 32:189-95. [PMID: 8655186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Conformational features of the DNA segment d-(GAATTCCGTTATT) containing the complementary Myb responsive element CCGTTA has been studied by NMR and molecular dynamics calculations with a view to see the role of 3D structure in specific DNA recognition. From the low field imino proton NMR spectra, the DNA sequence is seen to exist as a duplex with pyrimidine mismatches in the centre. The 2D NMR spectra however show that teh molecule exhibits substantial dynamism even at 1 degree C. Several extra cross peaks, more than the expected number, are seen in particular regions in all the spectra. These observations indicate that the duplex undergoes slow transitions between base-paired and unbase-paired states due to mismatches in the centre. Hence, to characterise those transitions a restrained verlet dynamics has been performed for 50ps using X-PLOR force field. Structural intermediates at regular intervals have been analysed, and we see that the dynamism in the molecule results in substantial fluctuations in the different torsion angles. The mismatch sites are seen to exhibit the highest degree of fluctuations, with the bases stacking in and looping out of the duplex. The sugar geometry is seen to be fairly steady around the S domain for most of the residues.
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Madan A, Radha PK, Srivastava A, Padhy LC, Hosur RV. The DNA-binding domain of Drosophila melanogaster c-Myb undergoes a multistate denaturation. EUROPEAN JOURNAL OF BIOCHEMISTRY 1995; 230:733-40. [PMID: 7607246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The DNA-binding domain of Drosophila c-Myb protein has been studied using different spectroscopic probes, namely CD, fluorescence, acrylamide quenching and NMR, to determine the structure of some of its sub-domains and their relative stabilities in aqueous solutions. While CD and fluorescence spectroscopy showed that the protein had completely lost its tertiary and secondary structures in approximately 3 M urea, solvent accessibility of the tryptophan residues was still partial, as determined by acrylamide quenching. This suggested the presence of significant amounts of residual structure which persisted until the urea concentration was raised to approximately 6.0 M. Thermal-denaturation experiments also indicated the presence of an intermediate in the unfolding pathway. The experimental data could be fitted assuming a minimum of three states in both modes of denaturation. The thermodynamic parameters for the apparent three-state transition have been determined. From the protein stability curve, we have determined that Drosophila melanogaster Myb R123 has maximal stability at 16 degrees C and pH 7.0.
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Madan A, Lin C, Hatch SL, Curtin PT. Regulated basal, inducible, and tissue-specific human erythropoietin gene expression in transgenic mice requires multiple cis DNA sequences. Blood 1995; 85:2735-41. [PMID: 7742534] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Erythropoietin (Epo) gene expression in kidney and liver is inducible by anemia. To localize the sequences necessary for regulated expression of the Epo gene, we constructed transgenic mice containing five human Epo gene constructs and examined Epo expression under basal conditions and with anemia. Mice containing the Epo gene with 0.3 kb of 5' flanking sequence, 0.7 kb of 3' flanking sequence, and either all introns or only intron I alone were polycythemic, had Epo expression in various tissues (including non-Epo-producing tissues), and induction only in liver. In contrast, mice containing the Epo gene with 8.5 kb of 3' flanking sequence and either 9.5 or 22 kb of 5' flanking sequence had basal expression at low levels in appropriate tissues and were less likely to be markedly polycythemic. Mice with the smaller of these two constructs had induction only in the liver, whereas those with the larger construct had induction in the kidney and liver. These studies indicate that sequences sufficient for induction in the liver are located in close proximity to the Epo gene, including the immediate 5' and 3' flanking sequence and the first intron. They also indicate that sequences required for induction in the kidney are located more than 9.5 kb 5' to the gene. Furthermore, comparison of these and prior transgenic studies suggest that sequences that limit the basal expression of the Epo gene are located downstream of the gene. We conclude that multiple cis DNA sequences are required for regulated Epo gene expression.
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Radha PK, Madan A, Nibedita R, Hosur RV. Solution structure of the conserved segment of the Myb cognate DNA sequence by 2D NMR, spectral simulation, restrained energy minimization, and distance geometry calculations. Biochemistry 1995; 34:5913-22. [PMID: 7727449 DOI: 10.1021/bi00017a021] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Solution structure of a self-complementary DNA duplex d-ACCGTTAACGGT containing the TAACGG recognition segment of Myb protein has been obtained by NMR spectroscopy. Complete resonance assignments of all the protons (except H5', H5" protons) have been obtained following standard procedures based on two-dimensional NMR techniques. Using a total of 72 coupling constants, and 95 NOE intensities, restrained energy minimization has been carried out, with the X-PLOR force field. The distance constraint set has been iteratively refined, for better fits with experimental NOE intensities. Using the final constraint set thus obtained, and explicit H-bond constraints for A.T, G.C base pairs in the duplex, distance geometry calculations have been carried in the torsion angle space with the program TANDY-2S to identify the family of structures consistent with the NMR data. We observe that the constraint set does indeed define a unique structure for the DNA segment. The structural details have been analyzed, and the sequence-dependent variations in torsion angles, base pair geometries, and helicoidal parameters have been documented. We observed that the helix axis displays a nonregular path, and three centered H-bonds have been seen at AA, AC, and CC steps in the major groove of the helix. Substantial variations have been observed for the helix axis and the groove widths at the recognition site. The base pairs exhibit high negative propeller twists. The structure is characterized by O4'-endo geometry for all the sugar rings (expect G10), and the other torsion angles belong to the B-DNA families.
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Madan A, Faiman MD. Characterization of diethyldithiocarbamate methyl ester sulfine as an intermediate in the bioactivation of disulfiram. J Pharmacol Exp Ther 1995; 272:775-80. [PMID: 7853193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Disulfiram is bioactivated through a series of intermediates, ultimately forming S-methyl-N,N-diethylthiolcarbamate sulfoxide (DETC-Me sulfoxide), the metabolite proposed to be responsible for the in vivo inhibition of rat liver mitochondrial low Km aldehyde dehydrogenase (ALDH2). Diethyldithiocarbamate methyl ester sulfine (DDTC-Me sulfine) also has been recently identified as a possible metabolite of disulfiram (Madan and Faiman, 1994). In the present studies, DDTC-Me sulfine was characterized and was found to inhibit ALDH2 in vivo (ID50 = 57 mumol/kg) but not in vitro. Maximum inhibition of ALDH2 in rats was observed 1 hr after the i.p. administration of DDTC-Me sulfine. Pretreatment of rats with 1-benzylimidazole, a cytochrome P450 inhibitor, blocked the DDTC-Me sulfine-mediated inhibition of ALDH2. This suggested that DDTC-Me sulfine was further bioactivated by a cytochrome P450-dependent mechanism. DDTC-Me sulfine could not be detected in rat plasma after the i.p. administration of disulfiram (75 mg/kg), DDTC-Me (122 mg/kg) or DDTC-Me sulfine (22.6 mg/kg). However, S-methyl N,N-diethylthiolcarbamate (DETC-Me), the desulfurated form of DDTC-Me, was detected as a major metabolite of DDTC-Me sulfine in rat plasma after DDTC-Me sulfine administration. Also, a disulfiram-like-ethanol reaction was observed in rats treated with DDTC-Me sulfine and challenged with ethanol. These data provided additional support for the idea that DDTC-Me sulfine is an intermediate formed after DDTC-Me metabolism and is probably a precursor to DETC-Me in the overall bioactivation of disulfiram to DETC-Me sulfoxide.
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Madan A, Williams TD, Faiman MD. Glutathione- and glutathione-S-transferase-dependent oxidative desulfuration of the thione xenobiotic diethyldithiocarbamate methyl ester. Mol Pharmacol 1994; 46:1217-25. [PMID: 7808445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Oxidative desulfuration of diethyldithiocarbamate methyl ester (DDTC-Me), a thione xenobiotic and a metabolite of disulfiram, was studied. Using a rat liver microsomal incubation system, DDTC-Me was oxidized at the thionosulfur group, forming DDTC-Me sulfine. Only minimal desulfuration of DDTC-Me to S-methyl-N,N-diethylthiolcarbamate (DETC-Me) occurred. Desulfuration of DDTC-Me increased 4-fold when the microsomal incubation was supplemented with reduced glutathione (GSH) and increased 8-fold when both GSH and glutathione-S-transferase (EC 2.5.1.18) were added. Similar results were obtained using a simplified system containing DDTC-Me sulfine, GSH, and glutathione-S-transferase. This suggested that DDTC-Me sulfine is a stable intermediate formed before DDTC-Me is desulfurated to DETC-Me. This unprecedented desulfuration process can be explained as follows. GSH attacks the oxithiirane isomer of DDTC-Me sulfine, resulting in ring opening followed by loss of glutathione hydrodisulfide, which is reduced by GSH to oxidized glutathione and H2S. GSH can also reduce DDTC-Me sulfine to DDTC-Me. This mechanism is supported by in vitro studies. An approximately 1:1 stoichiometry was observed for the formation of H2S and DETC-Me. A 1:1 stoichiometry was also observed for the consumption of DDTC-Me sulfine, formation of DETC-Me plus DDTC-Me, and formation of oxidized glutathione. Glutathione hydrodisulfide was trapped by derivatization in situ using 4-vinylpyridine. Oxidative desulfuration of a series of dithiocarbamate esters also followed a similar mechanism.
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Madan A, Faiman MD. Diethyldithiocarbamate methyl ester sulfoxide, an inhibitor of rat liver mitochondrial low Km aldehyde dehydrogenase and putative metabolite of disulfiram. Alcohol Res 1994; 18:1013-7. [PMID: 7978080 DOI: 10.1111/j.1530-0277.1994.tb00075.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
S-methyl N,N-diethylthiolcarbamate sulfoxide (DETC-MeSO) is a potent inhibitor of rat liver mitochondrial low Km aldehyde dehydrogenase (ALDH2) both in vivo and in vitro, and has been proposed to be the metabolite responsible for ALDH2 inhibition by disulfiram. Diethyldithiocarbamate methyl ester (DDTC-Me), a key intermediate in the metabolism of disulfiram, has been shown to be bioactivated by microsomal monooxygenases to diethyldithiocarbamate methyl ester sulfoxide (DDTC-Me sulfoxide). Studies were conducted to determine if DDTC-Me sulfoxide was also an active metabolite of disulfiram and inhibitor of ALDH2. DDTC-Me sulfoxide inhibited ALDH2 in vitro with an IC50 of 10 microM, and in vivo with an ID50 of 31 mg/kg (170 mumol/kg). Maximal ALDH2 inhibition in vivo was observed 8 hr after the administration of 45.2 mg/kg DDTC-Me sulfoxide, with ALDH2 activity returning to control levels after 48 hr. Although DDTC-Me sulfoxide inhibited ALDH2 in vivo, DDTC-Me sulfoxide was not detected in plasma from rats treated with either disulfiram (75 mg/kg), DDTC-Me (122.25 mg/kg), or DDTC-Me sulfoxide (45.2 mg/kg). However, DDTC-Me and S-methyl N,N-diethylthiolcarbamate (DETC-Me) were detected in plasma from rats treated with DDTC-Me sulfoxide. In rats treated with DDTC-Me sulfoxide and challenged with ethanol, a small increase of approximately microM in blood acetaldhyde and an inconsistent drop in blood pressure was observed. In conclusion, DDTC-Me sulfoxide inhibited ALDH2 in vitro and in vivo, was less potent than DETC- MeSO, and was not detected after disulfiram administration.
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Suckow M, Madan A, Kisters-Woike B, von Wilcken-Bergmann B, Müller-Hill B. Creating new DNA binding specificities in the yeast transcriptional activator GCN4 by combining selected amino acid substitutions. Nucleic Acids Res 1994; 22:2198-208. [PMID: 8036145 PMCID: PMC523674 DOI: 10.1093/nar/22.12.2198] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The specificity of the GCN4/DNA complex is mediated by a complicated network of interactions between the basic regions of both GCN4 monomers and their target halfsites. According to X-ray analyses (1, 2) one particular thymine of the target sequence is recognized by serine -11 and alanine -15 (we define the leucine in the first d-position of the heptad repeats as +1). We replaced serine -11 or alanine -15 with all other amino acids and analysed the DNA binding properties of the resulting stable GCN4 derivatives by electrophoretic mobility shift assays. Among these, mutants with tryptophan in position -11, or glutamic acid and glutamine in position -15, differ significantly from GCN4 in their DNA binding specificities. We then constructed selected double mutants, which differ from GCN4 in positions -11, -15 or -14 (3) of the basic region. The double mutants with tryptophan in position -11 and asparagine or serine in position -14 show drastically altered DNA binding specificities, presumably due to additive effects.
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Madan A, Hosur RV, Padhy LC. Sequence-specific DNA displaces 6-p-toluidino-2-naphthalenesulfonate bound to a hydrophobic site on the DNA-binding domain of Drosophila c-myb. Biochemistry 1994; 33:7120-6. [PMID: 8003478 DOI: 10.1021/bi00189a015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The N-terminal DNA-binding domain of c-myb oncoprotein binds to DNA in a sequence-specific manner. The domain, consisting of three imperfect tandem repeats, has tryptophan residues at very regular intervals and this is believed to be of some significance in the DNA-binding activity of the protein. We have found that the hydrophobic-site-specific probe 6-p-toluidino-2-naphthalenesulfonate (TNS) binds to the bacterially expressed DNA-binding domain of Drosophila c-myb protein (R123). TNS has a single binding site on this protein with an apparent dissociation constant in the range of (5-8) x 10(-7) M. When the TNS-protein complex was treated with an oligomeric DNA duplex having a cognate myb-binding site, the TNS was displaced from the complex. Nonspecific DNA duplex oligomers were ineffective, indicating that TNS displacement was a sequence-specific process. We examined further some features of the TNS-binding site on the protein, taking advantage of the fluorescence properties of the protein and the bound TNS. Our data indicate that the TNS binding occurs in a peripheral site on the protein in a manner that allows the bound TNS to be solvent accessible. Furthermore, there are indications that tyrosine(s) and tryptophans of the protein mediate resonance energy transfer to the bound TNS. From fluorescence-quenching data of the protein and protein-TNS complex, we could assess that both solvent-accessible and internal tryptophans are in the vicinity of the bound TNS. (ABSTRACT TRUNCATED AT 250 WORDS)
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Nagendra SN, Madan A, Faiman MD. S-methyl N,N-diethylthiolcarbamate sulfone, an in vitro and in vivo inhibitor of rat liver mitochondrial low Km aldehyde dehydrogenase. Biochem Pharmacol 1994; 47:1465-7. [PMID: 8185656 DOI: 10.1016/0006-2952(94)90350-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
S-Methyl N,N-diethylthiolcarbamate sulfone (DETC-Me sulfone) was investigated for its rat liver mitochondrial low Km aldehyde dehydrogenase (ALDH2) inhibitory properties. DETC-Me sulfone inhibited ALDH2 in vitro (IC50 = 3.8 microM) and in vivo (ID50 = 170 mumol/kg; 31 mg/kg). Maximum inhibition (60%) of ALDH2 was observed 8 hr after DETC-Me sulfone administration. In addition, incubation of S-methyl N,N-diethylthiolcarbamate (DETC-Me) or S-methyl N,N-diethylthiolcarbamate sulfoxide (DETC-Me sulfoxide) with rat liver microsomes and an NADPH-generating system failed to produce DETC-Me sulfone. Furthermore, DETC-Me sulfone could not be detected in plasma from rats treated with either DETC-Me sulfoxide or DETC-Me sulfone. In conclusion, DETC-Me sulfone inhibited ALDH2 in vitro and in vivo. However, there was no evidence suggesting that DETC-Me sulfoxide was metabolized to DETC-Me sulfone.
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92
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Madan A, Faiman MD. NADPH-dependent, regioselective S-oxidation of a thionosulfur- and thioether-containing xenobiotic, diethyldithiocarbamate methyl ester by rat liver microsomes. Drug Metab Dispos 1994; 22:324-30. [PMID: 8013289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The present study describes the NADPH-dependent, regioselective oxidation of diethyldithiocarbamate methyl ester (DDTC-Me), a dithiocarbamate ester containing both a thionosulfur (C = S) and a thioether (S-CH3) group, to two novel S-oxidized metabolites. DDTC-Me is a key metabolite in the overall bioactivation pathway for the clinically used alcohol deterrent, disulfiram. Incubation of DDTC-Me with rat liver microsomes resulted in the formation of two major metabolites. These metabolites were identified as DDTC-Me sulfoxide [S(O)CH3] and DDTC-Me sulfine (C = S+-O-) based on their NMR spectra and by MS. The formation of DDTC-Me sulfoxide was completely inhibited by the cytochrome P-450 inhibitors, emulgen 911 and 1-benzylimidazole, but only partially inhibited by heat inactivation of the flavin-containing moonooxygenases (FMO). This suggested that DDTC-Me sulfoxide formation is primarily catalyzed by cytochrome P-450 with a minor contribution from FMO. In contrast, the formation of DDTC-Me sulfine was inhibited from 60 to 80% in the presence of emulgen 911 and 1-benzylimidazole and 30 to 50% by heat inactivation of FMO, suggesting a partial role of FMO in the formation of DDTC-Me sulfine. DDTC-Me sulfoxide is a new class of dithiocarbamates that has not been previously described, whereas, DDTC-Me sulfine belongs to a class of thionosulfur sulfines that have been implicated in a number of toxicological processes.
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93
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Madan A, van Rooij WJ, Verpalen MC. Sonographically guided needle biopsy in peripheral thoracic masses: results in 50 patients. ROFO-FORTSCHR RONTG 1994; 160:75-7. [PMID: 8305697 DOI: 10.1055/s-2008-1032376] [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: 01/29/2023]
Abstract
50 patients with thoracic lesions were selected for percutaneous biopsy guided by real-time sonography. The indications were pulmonary, pleural and mediastinal lesions which made contact with the chest wall and sonographically accessible. Included were lesions near vital structures in the mediastinum (n = 3), in the apex of the lung (n = 8), small pulmonary nodules in contact with the chest wall (n = 24), lesions with intervening pleural fluid (n = 2), pleural nodules (n = 9) and masses arising from the chest wall itself (n = 4). A definitive diagnosis was established in 38 of the 45 (84.4%) malignant lesions and in 4 of the 5 (80%) benign lesions. Complications were restricted to one pneumothorax. Sonographically guided biopsy can be carried out as a bedside procedure. Real-time monitoring compensates for respiratory movements. Its role is curbed by intervening air such as in aerated lung, pneumothorax or primarily cavitatory lesions.
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94
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Madan A, Parkinson A, Faiman MD. Role of flavin-dependent monooxygenases and cytochrome P450 enzymes in the sulfoxidation of S-methyl N,N-diethylthiolcarbamate. Biochem Pharmacol 1993; 46:2291-7. [PMID: 8274163 DOI: 10.1016/0006-2952(93)90620-c] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Disulfiram is bioactivated to S-methyl N,N-diethylthiolcarbamate sulfoxide (DETC-MeSO), the metabolite proposed to be responsible for the action of disulfiram as an aldehyde dehydrogenase inhibitor. This bioactivation process includes a reduction, an S-methylation, and two successive oxidations. Sulfur-containing functional groups are substrates for cytochrome P450 enzymes or flavin-containing monooxygenases (FMO). In the present study, we investigated the contribution of these monooxygenases to the formation of DETC-MeSO from its immediate precursor S-methyl N,N-diethylthiolcarbamate (DETC-Me). Liver microsomes obtained from mature male rats were incubated with DETC-Me. The formation of DETC-MeSO was blocked completely by solubilization of the microsomes with the detergent Emulgen 911, or by the presence of the cytochrome P450 inhibitor 1-benzylimidazole. However, thermal-inactivation of FMO resulted in only a partial loss in DETC-MeSO formation. Liver microsomes from phenobarbital-treated rats showed a 4- to 5-fold increase in the rate of formation of DETC-MeSO, compared with controls. Liver microsomes from pyrazole-treated rats showed a 50% decrease in the sulfoxidation of DETC-Me compared with controls. In a purified reconstituted system, cytochrome P450 2B1 (CYP2B1) catalyzed the formation of DETC-MeSO at a rate of 51 nmol DETC-MeSO formed/min/nmol cytochrome P450. Antibodies to CYP2B1 caused a 60% inhibition of DETC-MeSO formation by liver microsomes from phenobarbital-treated rats. These results suggest that in male rat liver microsomes, cytochrome P450 plays a major role in catalyzing the sulfoxidation of DETC-Me, whereas FMO plays a minor role (< 10%). Also, in liver microsomes from phenobarbital-treated rats, CYP2B1 is the major catalyst for the sulfoxidation of DETC-Me.
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95
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Modi S, Madan A, Behere DV, Mitra S. Circular dichroism studies of acid⇌alkaline transition on hemeproteins. J CHEM SCI 1993. [DOI: 10.1007/bf02877479] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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96
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Madan A, Curtin PT. A 24-base-pair sequence 3' to the human erythropoietin gene contains a hypoxia-responsive transcriptional enhancer. Proc Natl Acad Sci U S A 1993; 90:3928-32. [PMID: 8387202 PMCID: PMC46419 DOI: 10.1073/pnas.90.9.3928] [Citation(s) in RCA: 102] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Erythropoietin (Epo) synthesis increases in response to hypoxia. The hepatoma cell line Hep 3B produces low basal levels of Epo mRNA which increase markedly with hypoxia. To define the sequences necessary for this response, we linked fragments of the human Epo gene to a luciferase vector, introduced these plasmids into Hep 3B cells and assayed for luciferase activity after growth in 1% or 21% oxygen. A 621-bp Epo promoter fragment resulted in a 2.4-fold increase in luciferase activity with hypoxia. We tested several Epo gene fragments upstream of this Epo promoter fragment and found that a 613-bp Bgl II-Pvu II 3' fragment had a 10-fold increase in activity with hypoxia regardless of orientation. This fragment had a similar level of activity when linked to a simian virus 40 promoter. Portions of this fragment retained activity, including a 38-bp Apa I-Taq I fragment that had a 17-fold increase in activity with hypoxia. Deletion of nt 4-13 or 19-28 from this 38-bp fragment resulted in a loss of activity. The 24-bp upstream portion of the 38-bp fragment showed an 8-fold increase in activity with hypoxia. However, deletion of nt 19-24 or mutagenesis of nt 21 or 22 in this 24-bp fragment resulted in loss of activity. Our studies indicate that the transcriptional response of the human Epo gene to hypoxia is mediated in part by promoter sequences and to a greater degree by an enhancer element located in a 24-bp portion of the 3' flanking sequence of the gene.
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97
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Madan A, Lavine JE, Heyman MB, Townsend SF. Acute hemorrhagic gastritis in the newborn infant. J Perinatol 1992; 12:377-80. [PMID: 1479465] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
We report three cases of hemorrhagic gastritis in term infants that led to massive bleeding of life--threatening proportions in the first 24 hours of life. In all three cases, bleeding was controlled by conservative therapeutic management. Management of this unusual entity in the newborn infant is discussed.
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98
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Madan A, Parisi M, Wood BP. Radiological case of the month. Absent pulmonic valve presenting with congenital lobar emphysema. AMERICAN JOURNAL OF DISEASES OF CHILDREN (1960) 1992; 146:113-4. [PMID: 1736636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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99
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Madan A, Dhar A, Kulshrestha PP, Laghate VD, Dhar P. Preliminary observation on drug resistant cases of typhoid fever. THE JOURNAL OF THE ASSOCIATION OF PHYSICIANS OF INDIA 1991; 39:449-51. [PMID: 1938845] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
We report here a sudden and marked increase in the occurrence, in a captive population, of typhoid fever cases showing multiple drug resistance. Fifty one cases of typhoid fever were seen from January '90 to June '90 of which 49% showed multiple drug resistance. Comparative figures for resistance in the previous three years were 0% (1987), 5% (1988), 14% (1989). Shared resistance to chloramphenicol, ampicillin, amoxycillin and sensitivity to gentamicin, kanamycin, sisomycin, cephazolin, norfloxacin and ciprofloxacin in most of our cases suggest infection by a common strain with R-factor, mediated resistance. The illness was prolonged and associated with serious complications. Therapy with combination of quinolone derivatives and aminoglycoside antibiotics seemed justified on the basis of the in-vitro tests and clinical response. Efforts to identify the strain and stern public health measures to prevent further development of drug resistant S typhi are urgently indicated.
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Jain NK, Madan A, Sharma TN, Sharma DK, Mandhana RG. Hepatopulmonary amoebiasis. Efficacy of various treatment regimens containing dehydroemetine and/or metronidazole. THE JOURNAL OF THE ASSOCIATION OF PHYSICIANS OF INDIA 1990; 38:269-71. [PMID: 2202709] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Thirty three patients with hepatopulmonary amoebiasis were studied. Pulmonary involvement was observed in 55%, pleuro-pulmonary lesions in 30%. Typical chocolate coloured sputum was obtained in 24% and pleural fluid in 21% of patients. Entamoeba histolytica were demonstrable in the sputum in only 6% and in the pleural fluid in 15%. The best therapeutic results were obtained with a combination of dehydroemetine and metronidazole. However, metronidazole was found to be nearly as effective as dehydroemetine, and metronidazole 400 mg and 800 mg were equally effective.
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