Publications by authors named "Sudev Namboodiri"

We examined trends in caller queries on tobacco, mammography, Pap tests, and clinical trials to the NCI-sponsored Cancer Information Service (CIS) of Ohio via its toll free telephone number (1-800-4-CANCER) during 1986-1991. Calls on NCI-approved clinical trials and treatment protocols tripled during the study period (from 6% in 1986 to 20% in 1991, p < 0.01) primarily due to counselor-initiated (proactive) recommendations and actions.

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Background: Epidemiologic studies have focused on the association between breast cancer risk and a variety of lifestyle and exogenous factors.

Purpose: The purpose of this study was to clarify the effects of alcohol consumption, cigarette smoking, oral contraceptive (OC) use, estrogen replacement therapy (ERT), and body mass on risk of breast cancer.

Methods: These variables were examined in a case-control study of 604 patients with newly diagnosed breast cancer and 520 control subjects who did not have breast cancer and were frequency matched for age, hospital, and time of diagnosis.

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Background: Diet, physical activity, obesity, aspirin use, and family history may all modify the risk of colon cancer, but few epidemiologic studies are large enough to examine these factors simultaneously.

Purpose: We prospectively assessed the relationship of diet and other factors to risk of fatal colon cancer.

Methods: Using data from Cancer Prevention Study II--an ongoing prospective mortality study--we studied 764,343 adults who, in 1982, completed a questionnaire on diet and other risk factors and did not report cancer or other major illness.

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Immunization of BALB/c mice with denatured DNA (dnDNA)-methylated bovine serum albumin (MBSA) complex along with aluminium hydroxide gel as adjuvant, resulted in the induction of anti-DNA antibodies of both IgG and IgE isotypes demonstrable by avidin-biotin micro enzyme-linked immunosorbent assay (ELISA) and solid phase radioimmunoassay (SPRIA), respectively. In contrast to the high levels of IgG2a and IgG2b anti-DNA antibodies observed in SLE-prone autoimmune mice, more than 90% of the anti-DNA antibodies of IgG isotype were found to be of IgG1 subclass. Specificity of both IgG and IgE antibodies which recognized activated DNA, dnDNA and double-stranded DNA but not RNA was established by competitive ELISA and SPRIA inhibition assays.

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Background And Methods: Experiments in animals and two epidemiologic studies in humans suggest that aspirin and other nonsteroidal antiinflammatory drugs (NSAIDs) may be protective against colon cancer. We tested this hypothesis in a prospective mortality study of 662,424 adults who provided information in 1982 on the frequency and duration of their aspirin use. Death rates from colon cancer were measured through 1988.

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Recently, we have developed a sequence-structure database of protein information, NRL_3D, that is extracted from the Protein Data Bank (PDB) of the Brookhaven National Laboratory. NRL_3D provides a vehicle for the retrieval of the three-dimensional coordinates of protein fragments as identified by sequence properties. These data are formulated to allow access by standard sequence analysis programs such as those provided by the Protein Identification Resource (PIR).

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Hematopoietic and lymphoproliferative cancer risk among the 3.7 million United States male veterans who use the Veterans Administration (VA) medical system annually was assessed using age-specific incidence curves and cumulative incidence rates. Relative risk comparing the VA with general population risk estimates from the Surveillance, Epidemiology, and End Results (SEER) data were increased significantly for all malignancies examined.

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N-acetylaspartate (NAA) is one of the most prevalent compounds in the mammalian nervous system. As such, NAA largely contributes to the major peak on water-suppressed proton magnetic resonance spectra. Highly specific antibodies to NAA demonstrate that this compound is discretely localized in a substantial number of neurons throughout the extent of the rat CNS.

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Arylamine and arylalkylamine N-acetyltransferase (NAT) activities were measured separately in different areas of the rat brain using specific substrates. Relatively high levels of arylamine NAT activity were detected in all areas examined. Arylalkylamine NAT activity in these areas ranged from 2 to 5% of the arylamine NAT activity.

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Evidence has been presented in recent years that support the hypothesis that N-acetylaspartylglutamate (NAAG) may be involved in synaptic transmission in the optic tract of mammals. Using a modified fixation protocol, we have determined the detailed distribution of NAAG immunoreactivity (NAAG-IR) in retinal ganglion cells and optic projections of the rat. Following optic nerve transection, dramatic losses of NAAG-IR were observed in the neuropil of all retinal target zones including the lateral geniculate nucleus, superior colliculus, nucleus of the optic tract, the dorsal and medial terminal nuclei and suprachiasmatic nucleus.

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The neuropeptide, N-acetylaspartylglutamate (NAAG), was identified in the chick retina (1.4 nmol/retina) by HPLC, radioimmunoassay and immunohistochemistry. This acidic dipeptide was found within retinal ganglion cell bodies and their neurites in the optic fibre layer of the retina.

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The presence of DNA-specific IgG4 antibodies was demonstrated in the sera of patients with systemic lupus erythematosus (SLE) by a microtiter solid-phase radioimmunoassay. A patient with distal interphalangeal swelling and extensive ulcers in the oral cavity, seronegative for anti-DNA antibodies of the IgG isotype, was found to have anti-DNA autoantibodies exclusively of the IgG4 subclass. These autoantibodies directed against the dsDNA conformation cross-reacted with chondroitin sulfate, dermatan sulfate and heparin.

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The results presented here show clearly that the rapid nocturnal increase in circulating melatonin in sheep is associated with an equally rapid increase in melatonin production in the pineal gland. Pineal NAT activity and NAS concentration also increased under this condition, indicating that NAT activity is an important factor in this process. According to the current model for the regulation of pineal melatonin production in the rat, the large nocturnal increase in NAT activity is the major factor responsible for the daily rhythm in melatonin, as well as for the opposite rhythm in serotonin and its oxidation products in the pineal gland.

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The protein identification resource (PIR) and the Brookhaven National Laboratory protein data bank (PDB) are well-known databases for primary sequences and three-dimensional structures of proteins, respectively. Lesk et al, have compared the primary sequences in these two databases and concluded that the sequences in them are not redundant. Moreover, PIR programs can not be used directly on PDB files to access primary sequences because the FORMATS of these two data bases are different.

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The retinohypothalamic tract is the neural pathway mediating the photic entrainment of circadian rhythms in mammals. Important targets for these retinal fibers are the suprachiasmatic nuclei (SCN) of the hypothalamus, which are thought to be primary sites for the biological clock. The neurotransmitters that operate in this projection system have not yet been determined.

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The photolabile (diazomethyl)carbonyl function was introduced into the 8-position of 2-(N,N-di-n-propyl-amino)-1,2,3,4-tetrahydronaphthalene in three ways, resulting in the ether 8-[[(diazomethyl)carbonyl]methoxy]-2-(N,N-di-n-propylamino)-1,2,3,4- tetrahydronaphthalene (2), the ester 8-(diazoacetoxy)-2-(N,N-di-n-propyl-amino)-1,2,3,4- tetrahydronaphthalene (3), and the ketone 8-[(diazomethyl)carbonyl]-2-(N,N-di-n-propylamino)- 1,2,3,4-tetrahydronaphthalene (4). Specific binding of these compounds at the 5-hydroxytryptamine1A sites in rat brain membranes labeled with 1 nM [3H]-8-hydroxy-2-(N,N-di-n-propylamino)- 1,2,3,4-tetrahydronaphthalene (8-OH-DPAT) showed IC50 values of ca. 75, 125, and 25 nM, respectively, for the three compounds.

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N-Acetylaspartylglutamate (NAAG), a neuron-specific dipeptide, was found by immunocytochemistry to be localized in specific compartments of the extrapyramidal system of the rat. Cellular and neuropil NAAG-like immunoreactivity (NAAG-IR) was evident throughout the pallidum, entopeduncular nucleus, subthalamic nucleus, and all subdivisions of the substantia nigra. By contrast, only a minority of cells of the caudate-putamen and those of the accumbens nucleus stained positively for NAAG.

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The GABAA receptor complex was solubilized from rat brain membranes in Triton X-100, enriched by 1012-S affinity chromatography, and subjected to DEAE anion-exchange chromatography. Two forms were distinguished by their differential elution during this HPLC with a KCl gradient. They displayed similar [3H]muscimol- and [3H]flunitrazepam-binding characteristics, as well as [3H]flunitrazepam-binding inhibition by CL 218872.

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A radiochemical procedure for measuring aspartate aminotransferase activity in the nervous system is described. The method is based on the exchange of tritium atoms at positions 2 and 3 of L-2,3-[3H]aspartate with water when this amino acid is transaminated in the presence of alpha-ketoglutarate to form oxaloacetate. The tritiated water is separated from the radiolabeled aspartate by passing the reaction mixture over a cation exchange column.

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Iodinated melatonin was used to study melatonin sites of action in brain. Iodomelatonin mimicked the effects of melatonin on reproductive development in Djungarian hamster fetuses. 125I-melatonin injected into the dam was recovered from fetal brain.

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Heterogeneity in determinants of familial resemblance of lipid and lipoprotein levels between populations in North America and Israel was investigated using path analysis. A common protocol, identical measurement techniques, and the same statistical procedures were used in the two samples. Both genetic (h2) and cultural (c2) determinants of inheritance were significant for all lipid variables in the two studies.

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