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Biomedical subjects

S P Dutta

Publications and source records attributed to S P Dutta.

At least 19 recordsLinked to original sources
PubMed1999

Isolation and characterization of 5-carbamoylmethyluridine and 5-carbamoylmethyl-2-thiouridine from human urine.

Two new modified uracil nucleosides, 5-carbamoylmethyuridine (ncm5U, I) and 5-carbamoylmethyl-2-thiouridine (ncm5s2U, II) were isolated from a 24 hr collection of a normal human urine. The structures were assigned on the basis of UV, NMR and mass spectral data and confirmed by comparison of the spectral data and HPLC mobilities with those of authentic samples. On the basis of experimental data it appears possible that 5-carbamoylmethyl-2-thio-uridine (ncm5s2U, II) may be a degradation product produced from a labile precursor by the chemical treatments during the isolation procedure. However, the other nucleoside (ncm5U,I) certainly appears to be of metabolic origin and was also found in the urines of one chronic myelogenous leukemia and one lung carcinoma patient. Abbreviations used are: tRNA-transfer ribonucleic acid, TMS-trimethylsilyl, RP-HPLC--reverse phase high performance liquid chromatography, EI--electron impact, cm5U-5-carboxymethyluridine, mcm5U-5-methoxycarbonylmethyluridine, cm5s2U-5-carboxymethyl-2-thiouridine, mcm5s2U-5-methoxycarbonylmethyl-2-thiouridine, t6A-9-beta-D-ribofuranosyl-[N(purin-6-yl)carbamoyl]-1-threonine, C-cytidine, acp3u-3-(3-amino-3-carboxypropyl)uridine, AICR-aminoimidazole carboxamide riboside, alpha-4-PCNR & beta-4-PCNR-9-alpha-D-(or beta-D)-ribofuranosyl-pyridin-4-one-3-carboxamide, H x 7R-7-beta-D-ribofuranosyl hypoxanthine, m3U-3-methyluridine, m1I-1-methylinosine, m1G-1-methylguanosine, DI-5'-deoxyinosine, dms5OA-5'-deoxy-5'-methylthioadenosine sulfoxide, m2(2)G-N2-dimethylguanosine, psi-psi-uridine, A-adenosine, I-inosine, CML-chronic myelogenous leukemia mam5s2U-5-methylaminomethyl-2-thiouridine, ncm5U-5-carbamoylmethyluridine, ncm5s2U-5-carbamoylmethyl-2-thiouridine, UV-ultraviolet, NMR-nuclear magnetic resonance, HPLC-high performance liquid chromatography, GC-MS-gas chromatography-mass spectrometry.

Chromatography, High Pressure Liquid↗
PubMed1993

Mass spectrometric investigation of the presence of 7-methyl ring-opened guanine derivatives in urine.

The involvement of chemical alkylating agents in tumorigenesis and chemotherapy is well established and it was shown that one of the main sites of alkylation is the N-7 of guanine in DNA. Though excision of damaged bases is regarded as one of the repair mechanisms in damaged DNA there is a scarcity of information concerning the excised final metabolites in body fluids. This study attempts to demonstrate the usefulness of CAD MS/MS for the detection of the final metabolite-deformylated ring-opened 7 alkylguanine in urine. Such mass spectrometric methods can be used in biomedical studies.

Alkylation↗
PubMed1989

Developing norms for manual carrying tasks using mechanical efficiency as the optimization criterion.

The primary objective of this investigation was to determine optimum activity levels when carrying symmetrical loads in front of the body. Efficiency of mechanical work was used as the response variable for optimization purposes. This was defined as the ratio between the rate of energy transfer between and within body segments (Wwb) and the rate of net metabolic energy expenditure during the task (RNME). Response surface methodology was used to develop a model describing the relationship between the efficiency of mechanical work and three task related variables, i.e., load handled, frequency of handling and carrying distance. It was determined that a maximum efficiency of 31.74% is achieved under a combination of task conditions as follows: load = 16.72 kg; frequency = 3.64 handlings/min and carrying distance = 10.61 m. The implications of these findings are discussed in the paper.

Adult↗
PubMed1988

Identification of cis-dichloro-bis-isopropylamine platinum(II) as a major metabolite of iproplatin in humans.

Iproplatin is a quadrivalent second-generation platinum complex undergoing clinical evaluation. In plasma and urine of patients receiving this drug, iproplatin- and platinum-containing metabolites of iproplatin were separated by reverse-phase gradient high performance liquid chromatography. One of the metabolites was identified by cochromatography and electron impact mass spectrometry as cis-dichloro-bisisopropylamineplatinum(II), a metabolite formed by reduction of iproplatin. Incubation of iproplatin with ascorbic acid and cysteine, in vitro, indicates that iproplatin can be easily reduced to cis-dichloro-bis-isopropylamineplatinum(II) by reducing agents. It is hypothesized that the reduction of the quadrivalent complex iproplatin to cis-dichloro-bisisopropylamineplatinum(II) occurs intracellularly.

Antineoplastic Agents↗
PubMed1987

Metabolism of 1-methyladenosine.

1-[methyl-8-14C] Adenosine was synthesized and its metabolic fate was determined in intact rat. It was found that approximately 57% of 1-[methyl-8-14C] adenosine administered iv was excreted unchanged in the urine and 33% of the excreted radioactivity in the urine was associated with the major metabolite 1-methyl-hypoxanthine and about 4.5% was associated with 1-methylinosine. Very little adenosine or N6-methyladenosine was formed. It is concluded that 1-methyladenosine is initially deaminated by adenosine deaminase to 1-methylinosine which is then cleaved by nucleoside phosphorylase to 1-methylhypoxanthine.

Adenosine↗
PubMed1985

Isolation and characterization of a novel nucleoside, 7-beta-D-ribofuranosylhypoxanthine, from the urine of a chronic myelogenous leukemia patient.

A novel nucleoside, in the amount of 400 micrograms, was isolated from a 24-h collection of urine of a chronic myelogenous leukemia patient. On the basis of ultraviolet, nuclear magnetic resonance, and mass spectrometry and chromatography, its structure was established to be 7-beta-D-ribofuranosylhypoxanthine. The ultraviolet and mass spectral data and the thin layer chromatographic mobilities of the natural material were identical to those of a synthetic sample. High performance liquid chromatographic retention times and the coinjection high performance liquid chromatography of the natural material with the synthetic samples of the alpha and beta-anomers of 7-ribofuranosylhypoxanthines further confirmed the identity of the isolated material as 7-beta-D-ribofuranosylhypoxanthine.

Adult↗
PubMed1975

Purine and pyrimidine inhibitors of arginase.

1. Adenosine, inosine, adenine and uric acid are competitive inhibitors and cytidine and cytosine noncompetitive inhibitors of bovine liver arginase (L-arginine amidinohydrolase, EC 3.5.3.1). 2. The affinity of the enzyme for these inhibitors was 10--100 times as great as for substrate in terms of Ki versus Km. 3. These nucleic acid metabolites may thus function in vivo to regulate the urea cycle. 4. Several naturally occuring competitive and noncompetitive inhibitors of arginase of unknown structure have been isolated from plant and animal tissue. From their properties and methods of isolation, they may be the purines and pyrimidines herein described. 5. These purines and pyrimidines have no effect on tryptic hydrolysis.

Animals↗
PubMed1975

Synthesis properties of the naturally occurring N-[(9-beta-D-ribofuranosylpurin-6-yl)-N-methylcarbamoyl]-L-threonine (mt-6A) and other related synthetic analogs.

The naturally occurring modified nucleoside, N-[(9-beta-D-ribofuranosylpurin-6-yl)-N-methylcarbamoyl]-L-threonine (mt6A), and the corresponding glycine analog mg6A were synthesized from N6-methyl-2',3',5'-tri-O-acetyladenosine and the appropriately blocked isocyanates derived from threonine and glycine. The natural mt6A isolated from Escherichia coli tRNA (F. Kimura-Harada et al. (1972), Biochemistry 11, 3910), from wheat embryo tRNA (R. Cunningham and M. W. Gray (1974), Biochemistry 13, 543), and from rat liver tRNA (Rogg et al. (1975), Eur. J. Biochem. 53, 115) was found to be identical with the synthetic mt6A in paper and thin-layer chromatography and electrophoresis. Several analogs of the parent 6-ureidopurine ribonucleoside, N-[(9-beta-D-ribofuranosylpurin-6-yl)carbamoyl]-L-thronine (t6A), were also prepared. Starting from 2',3',5'-tri-O-acetylguanosine and 2',3',5'-tri-O-acetylcytidine and the above isocyanates, the t6A analogs, N-[(9-beta-D-ribofuranosyl-6-oxo-1H-purin-2-yl)carbamoyl]-L-threonine (t2G) and N-[(1-beta-D-ribofuranosyl-2-oxypyrimidin-4-yl)carbamoyl]-L-threonine (t4C), were prepared. Also synthesized were the corresponding glycine analogs, g2G and g4C, from guanosine and cytidine, respectively. The 2'-deoxyribosyl analog, N-[(9-beta-D-2'-deoxyribofuranosylpurin-6-yl)carbamoyl]-L-threonine (2'-deoxy-t6A), and the arabinosyl derivative, N-[(9-beta-D-arabinofuranosylpurin-6-yl)carbamoyl]-L-threonine (t6AraA), were synthesized from the appropriate urethane and the requisite amino acid. The ureido group in mt6A could not be hydrolyzed by the enzymes urease, peptidase, and protease. Various chemical and biological properties of the naturally occurring mt6A and the related analogs are discussed.

Chromatography, Paper↗
PubMed1975

Synthesis and biological activities of some N6-(nitro- and -aminobenzyl)adenosines.

Synthesis and biological activities of 12 analogs of N6-benzyladenosine are described. The compounds were prepared by two methods: (1) direct alkylation of adenosine with an appropriately substituted benzyl bromide to give the N1-substituted derivative which was then rearranged in base to give the N6-substituted compound, and (2) by nucleophilic displacement of chlorine in 6-chloropurine ribonucleoside, 6-chloro-2-aminopurine ribonucleoside, and 6-chloro-2-aminopurine with an amine. These analogs were examined for their growth inhibitory effect in cultured leukemic cells and also for their effect on adenosine aminohydrolase activity. N6-p-Nitrobenzyladenosine and its 2'-deoxy analog were competitive inhibitors (K1 65, 22 MUM). The 2-amino-N6-p-nitrobenzyladenine and its ribonucleoside were found to be noncompetitive inhibitors of adenosine aminohydrolase. In cultured L1210 leukemia, 2-amino-6-p-nitrobenzylaminopurine and the corresponding ribonucleoside were better growth inhibitors than N6-benzyladenosine, while N6-p-nitrobenzyladenosine, its 2'-deoxy analog, and N6-p-fluorobenzyladenosine were as active as N6-benzyladenosine.

Adenosine↗