PubMed Health⌕ Search

Biomedical subjects

V Iyengar

Publications and source records attributed to V Iyengar.

15 recordsLinked to original sources
PubMed2001

Fluorine determination in human and animal bones by particle-induced gamma-ray emission.

Fluorine was determined in the iliac crest bones of patients and in ribs collected from post-mortem investigations by particle-induced gamma-ray emission based on the 19F(p,p'gamma)19F reaction, using 2.0/2.5 MeV protons. The results indicate that for 68% of the human samples the F concentration is in the range 500-1999 microg g(-1). For comparison purposes fluorine was also determined in some animal bones; in some animal tissues lateral profiles of fluorine were measured.

Adolescent↗
PubMed1998

The application of preirradiation combustion and neutron activation analysis technique for the determination of iodine in food and environmental reference materials.

The pre-irradiation combustion (PC) of samples to liberate iodine, followed by trapping the iodine on charcoal and quantifying the element by neutron activation analysis (NAA), has been used at the National Institute of Standards and Technology for the determination of iodine in biological materials. The applicability of this technique to numerous environmental and dietary matrices is illustrated by analysis of a range of certified reference materials (CRMs) and a powdered grass material that was prepared as an in-house reference material (RM). Because of the combustion step involved, samples with low or no fat content (e.g., cereal products, selected botanical specimens, and nonfat milk powder) and inorganic materials (e.g., coal fly ash and dried sediments) are more suited for analysis by this method. In general, the results for several types of samples obtained by this method agreed with those obtained by a second radiochemical (R) NAA, as well as by a third method using inductively coupled plasma mass spectrometry (ICP-MS). PC-NAA is a useful technique for determining iodine in biological and environmental samples, especially for verification of iodine results obtained from other methods.

Environmental Pollutants↗
PubMed1998

Neurilemmomatosis, NF2, and juvenile xanthogranuloma.

The gene locus for neurilemmomatosis has been reported to lie within the neurofibromatosis type 2 gene region, suggesting that these 2 diseases may be identical. We describe an adolescent girl with multiple neurilemmomas and juvenile xanthogranulomas, who was found to have bilateral acoustic neuromas and multiple central nervous tissue tumors as seen in patients with a diagnosis of neurofibromatosis type 2. This case and recent genetic studies suggest that neurilemmomatosis and neurofibromatosis type 2 are the same disease.

Adolescent↗
PubMed1995

Synovial sarcoma of the heart. Correlation with cytogenetic findings.

A primary sarcoma of the heart was submitted to cytogenetic studies, which showed a translocation t(X;18)(p11;q11.2). The translocation between X and 18 is a characteristic one in synovial sarcoma of the lower extremities. As the histological appearance was not helpful for further classification of this primary sarcoma, karyotypic analysis proved useful in confirming diagnosis of synovial sarcoma, which, to our knowledge, is an uncommon neoplasm in the heart.

Adult↗
PubMed1994

Determination of tin in biological materials by atomic absorption spectrophotometry and neutron activation analysis.

Concentrations of Tin (Sn) were determined in botanical, dietary and biological reference materials (RMs), and in human livers from Japanese and American subjects using atomic absorption spectrophotometry (AAS) and neutron activation analysis (NAA), either in the instrumental mode (INAA) or in the radiochemical mode (RNAA). The mean Sn concentrations (+/- 1 S.D.) found in various RMs are: total diet (NIST SRM-1548) 3.57 +/- 0.52 and 3.61 +/- 0.52 microgram/g by AAS and INAA, respectively; non-fat milk powder (NIST SRM-1549) 2.5 +/- 1.4 ng/g and 1.9 +/- 0.3 ng/g; bovine liver (NBS SRM-1577) 18 +/- 2 and 20 +/- 0.3 ng/g; and citrus leaves (NIST SRM-1542) 0.25 +/- 0.02 and 0.243 +/- 0.006 microgram/g by AAS and RNAA, respectively. These comparisons demonstrate good agreement between the two methods. In apple leaves (NIST SRM-1515) and peach leaves (NIST SRM-1547), the measured concentrations by AAS were 77.1 +/- 20 and 85 +/- 15 ng/g; interferences by 160Tb did not permit an accurate assessment by INAA at this concentration. The Sn results obtained for the American human liver specimens by RNAA ranged from 0.135-0.712 microgram/g wet weight, and the Sn concentrations in Japanese human liver specimens determined by AAS ranged from 0.078-1.122 microgram/g wet weight in 23 individuals. The results from this study show that it is feasible to use INAA/RNAA and AAS in combination to establish recommended values in RMs.

Animals↗
PubMed1994

Excessive urinary excretion of zinc in drug addicts: a preliminary study during methadone detoxification.

Random samples of urine from control subjects, and subjects treated with methadone (an agonist of morphine) for drug addiction, were analyzed for calcium and trace elements zinc and copper. The following differences (based on creatinine) were observed between the two groups: Calcium excretion did not show any significant differences between the two groups (146 mmg/g creatinine vs. 135 mg/g creatinine vs. 33 +/- 3 micrograms/g creatinine in controls). However, the excretion of copper in drug addicts diminished (23 +/- 3 micrograms/g creatinine in controls; p < 0.05), while that of zinc was excessive (600 +/- 50 micrograms/g creatinine vs. 300 +/- 30 micrograms/g creatinine in controls; p < 0.001). The ever increasing link between zinc and immunity and the fact that drug addicts are susceptible to various infections such as hepatitis and acquired immuno deficiency syndrome raises concern about the excessive urinary loss of zinc in this group and calls for further investigations such as balance studies and intervention if necessary.

Female↗
PubMed1992

Isolation of exfoliated colonic epithelial cells, a novel, non-invasive approach to the study of cellular markers.

Human stool is a heterogeneous mixture of non-digestible food residues, bacteria, cells exfoliated from the gastrointestinal mucosa and other secretory products. We have demonstrated that fresh human stools dispersed in a buffered saline solution can be fractionated over Percoll/BSA gradients to yield 9 discrete bands of cells in the density range of rho 1.033 to 1.139 and which could be further purified over Histopaque 1077. Enzyme-linked immunoassays (ELISA) for colon-specific antigen (CSA) and cytokeratins (CK) were positive. Western blot analysis showed the presence of 3 cytokeratin bands in the 40-kDa to 60-kDa range suggestive of cytokeratins 8, 18, and 19. Fluorescence flow-cytometric analysis of these cells using antibodies against CSA, CK, the blood-group antigens, carcinoembryonic antigen (CEA), non-mucus-secreting columnar-epithelium-specific MAb PR1A3, and to mucus-secreting colonic-epithelium-specific MAb PR5D5 showed varying degrees of reactivity. Expression of the blood-group phenotype suggests that cells from the proximal half of the colon had survived the transit, since in the adult expression of this marker is limited to cells from the proximal region of the colon. In this report we demonstrate the feasibility of studying, non-invasively, cell-specific markers on exfoliated cells isolated from stools. The evidence strongly suggests that almost all the cells are of colonic origin.

Antigens, Neoplasm↗
PubMed1991

Human stools as a source of viable colonic epithelial cells.

Human stools consist of a mixture of undigested food residues, colonic microflora, and cellular components shed from the walls of the gastrointestinal tract. The cellular components are made up mostly of terminally differentiated colonic epithelial cells. Using a combination of Percoll density gradient centrifugation and countercurrent centrifugal elutriation, it is now possible to recover these cells as an enriched fraction from fresh human stools. Cells can be visualized on heat-fixed smears of the enriched fractions stained with modified Wright's stain. The enrichment process is optimized by following the segregation of eukaryotic cells as determined by an ELISA technique using monoclonal antibodies against human double-stranded DNA. This work, demonstrating the feasibility of isolating intact colonic cells from stools, has important applications as a noninvasive approach to the biology of exfoliated cells from the gastrointestinal tract.

Cell Count↗
PubMed1988

Biological trace element research: a multidisciplinary science.

The last decade may be regarded as a crucial turning point in new developments in many areas of biological trace element research. It is slowly being recognized as a multidisciplinary science which requires a combination of biological insight and analytical awareness in planning the studies. It is also acknowledged that the complexities involved in dealing with the requirements of trace element research studies in the life sciences demand comprehensive planning of the investigations and use of a variety of techniques, thus bringing together a variety of talents. It cannot be emphasized enough that accurate analytical measurements on biologically and analytically "valid" samples hold the key for success in future biological trace element research studies. These aspects are illustrated.

Food Analysis↗
PubMed1988

Studies of cholecystokinin-stimulated biliary secretions reveal a high molecular weight copper-binding substance in normal subjects that is absent in patients with Wilson's disease.

Copper is unique among cations in that its balance is regulated by the liver. The liver regulates copper balance by excretion of copper (we call it regulatory copper) in the bile destined for loss in the stool. However, most copper secreted into the gastrointestinal tract, for example, that in saliva and gastric juice, is reabsorbed. The biochemical mechanism by which the normal liver "packages" regulatory copper to prevent its reabsorption is not understood. Whatever the mechanism, it appears to have failed in Wilson's disease, because patients with Wilson's disease do not excrete adequate amounts of regulatory copper in their bile to prevent copper accumulation. In the present work, we have studied cholecystokinin-stimulated biliary secretions obtained by intestinal intubation of five normal subjects and five patients with Wilson's disease. Studies of these secretions reveal: (1) that normal but not Wilson's disease biliary samples had a copper-containing peak in the void volume from Sephadex G-75 columns; (2) that the amount of copper in this peak extrapolated to 24 hours of secretion was appropriate to maintain normal copper balance; (3) that the amount of copper in this peak increased with dietary copper supplementation of normal subjects; (4) that normal but not Wilson's disease biliary samples cross-reacted with each of two ceruloplasmin antibodies; and (5) that the high molecular weight Sephadex G-75 fraction from normal but not from Wilson's disease biliary samples cross-reacted with ceruloplasmin antibody. We postulate that the high molecular weight copper-containing substance observed with Sephadex chromatography in normal biliary samples but absent in Wilson's disease samples is the copper-packaging mechanism for copper balance regulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Bile↗
PubMed1988

Trace elements in human clinical specimens: evaluation of literature data to identify reference values.

Reference values are proposed for the concentrations of As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Mo, Pb, Se, and Zn in whole blood, blood serum, urine, milk, liver, and hair from adult human subjects. For F, I, and Ni, it was not possible to evaluate reference intervals for all the specimens mentioned above. For several elements, including Al, B, Br, Cs, Li, Rb, U, and V, the present status of the literature does not provide an adequate basis for formulating baseline concentrations; therefore, results from selected investigations are listed for information only. For elements such as Cu, Fe, and Zn, which are known to be homeostatically controlled, the concentrations in whole blood and blood serum follow a gaussian-like frequency distribution, and we could consider both median and mean values for evaluation. On the other hand, elements whose concentrations in tissues and body fluids are influenced by dietary availability (e.g., As and Se) or environmental factors (e.g., Cd, Hg, and Pb) show wide scatter. In these cases, the median appeared to be a better indicator of the central tendency than the mean, when different populations are involved. These points are illustrated.

Body Fluids↗
PubMedDate not supplied

Breast milk contamination in Kazakhstan: implications for infant feeding.

To assist the Ministry of Health of Kazakhstan in making infant feeding recommendations, breast milk samples were analyzed for PCDDs/PCDFs, PCBs, chlorinated pesticides, toxic metals, and cesium-137. Sampling sites were selected to provide a profile of representative exposures to possible contaminants; 92 breastmilk samples from 7 sites were analyzed for chlorinated contaminants and 115 samples from 8 sites were analyzed for toxic metals and cesium-137. With three important exceptions, concentrations of chlorinated contaminants and toxic metals were similar to or lower than those in Europe. Cesium-137 was not detected in any samples. The exceptions were localized contamination with the most toxic dioxin congener, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), and generalized contamination with beta-hexachlorocyclohexane and 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDT). The localized high concentrations of TCDD (range 6.2 to 118.2 pg/g fat) are the highest documented in the world in a population currently of reproductive age. Calculated incremental lifetime excess cancer risk to an infant exposed to these high concentrations of TCDD range from 28 to 82 x 10(-5). Based in part on the results of this study, the Ministry of Health is promoting breast feeding. However, possible adverse developmental effects associated with both prenatal and postnatal (through breast milk) TCDD exposure have not been adequately assessed. Further epidemiologic research is needed to examine these effects in this newly identified high-risk population.

Adolescent↗