PubMed Health⌕ Search

Biomedical subjects

G V Iyengar

Publications and source records attributed to G V Iyengar.

At least 19 recordsLinked to original sources
PubMed2000

Global outlook on nutrition and the environment: meeting the challenges of the next millennium.

As we enter the new millennium, nearly 800 million of the World's population will remain chronically malnourished. Nearly 200 million children are moderately to severely underweight, while 70 million are severely malnourished. And those who are yet to be born will be faced with the same set of circumstances that predispose them to malnutrition and its consequences. Eradication of nutritional deficiencies among women and children on a global scale are needed to ensure improved quality of life for the next generation of citizens. Primary deficiencies in vitamin A, iron, iodine, calcium, folic acid and trace elements such as zinc are compounded by pollutants caused by human activity. Environmental lead, arsenic, mercury, and other heavy metals that enter the food chain can seriously deplete body stores of iron, vitamin C and other essential nutrients leading to decreased immune defenses, intrauterine growth retardation, impaired psycho-social faculties and other disabilities associated with malnutrition. Increased susceptibilities to communicable diseases, and those provoked by water or insect borne vectors are additional risks encountered by malnourished individuals. Migration of populations from rural to urban centers and the expansion of major metropolitan areas have had a significant and adverse impact on the quality of life of these citizens. In the next 20 years most of the growth in urban populations will be in Asia and Latin America. Urbanization and the resultant burden on limited national resources is a major contributory factor to malnutrition. There are many other lifestyle-associated disabilities such as use of tobacco (cancer) and alcoholism that require active intervention. Within the family unit, socioeconomic factors and the status of women (literacy, economic independence) are major determinants of the quality of life. In the coming century, the World will have to meet these challenges by careful planning and international cooperation.

Adult↗
PubMed1999

Acquisition of improved reference values for cesium, iodine, strontium, thorium, and uranium in selected NIST reference materials.

As part of a study on the ingestion and organ content of some trace elements of importance in radiological protection, additional work has been undertaken to acquire improved reference values for cesium, iodine, strontium, thorium, and uranium in four selected reference materials provided by the US National Institute of Standards and Technology. The materials are SRM-1548 Total Diet, SRM-1548a Typical Diet, SRM-1486 Bone Meal, and RM-8414 Bovine Muscle. A coordinated study was undertaken with the help of seven selected laboratories in five countries. Instrumental and radiochemical neutron activation analysis and inductively coupled plasma-mass spectrometry were the analytical main techniques used.

Animals↗
PubMed1998

A review of radiologically important trace elements in human bones.

The authors recently compiled and reviewed the literature for minor and trace elements in human bones and teeth as a part of an International Atomic Energy Agency (IAEA) study. Various aspects of elemental composition, analytical methodologies, quality assurance and quality control methods for hard tissue analysis were evaluated. Important data on selected radiologically important elements (Cs, Pu, Ra, Sr, Th, and U) in calcified tissue from various countries are discussed. The results of this compilation study suggest a need for new reference materials with matrix properties similar to bones including one with separated cortical and trabecular segments.

Adult↗
PubMed1991

Milestones in biological trace element research.

Over 100 years ago, macro-scale analytical techniques were used to discover the roles of special compounds (especially of metallic elements) in living organisms, and investigations were focussed on selected proteins and pigments suspected of containing percentage quantities of metals. In contrast, present-day analytical techniques are capable of detecting extremely small quantities and have become routine ultra-trace measurement tools to probe elemental interactions at cellular levels. The scientific achievements connecting these two boundaries are punctuated with an array of analytical developments; some highlighting the phenomenal advances in the measurement technology and others reflecting the exceptional bioanalytical perception and the multi-disciplinary outlook of trace element investigators. An account of the events that contributed to the overall progress in biological trace element research is the essence of this communication.

Adult↗
PubMed1989

Nutritional chemistry of chromium.

There has been considerable progress in understanding the role of chromium in human nutrition. However, the lack of data on the forms of chromium-absorption from foods by the gastro-intestinal tract, and our concomitant inability to obtain an accurate assessment of the daily mobile pool of metabolically active chromium in the human body continues to be an impediment in assessing the overall impact of chromium nutrition. Based on recent chromium data on human tissues and body fluids available in the literature, an assessment of chromium content in different body compartments as well as in the total body is presented. However, on the analytical side, a few problems still persist and, therefore, a reliable analysis for chromium is restricted to a few selected laboratories.

Animals↗
PubMed1987

Preparation of a mixed human diet material for the determination of nutrient elements, selected toxic elements and organic nutrients: a preliminary report.

Using 201 foods from the United States Food and Drug Administration's Total Diet Study (FDA TDS), a mixed diet composite (USDIET-I) was prepared to represent the intake of 25-30-year-old males in the United States. Proximate analyses, phytate determination, and assays for nutrient elements and selected toxic elements, as well as organic nutrients were carried out on this composite. As part of a quality control exercise for a coordinated research program, atomic absorption spectrophotometry, inductively coupled atomic emission spectrometry, colorimetry and neutron activation analysis were used to determine up to 30 elements in this diet material. A comparison of the daily intakes of As, Ca, Cd, Cu, Fe, Hg, K, Mg, Mn, Na, P, Se and Zn from the composite USDIET-I shows excellent to good agreement with FDA TDS values calculated from results of single food analyses. These USDIET-I results demonstrate the feasibility of the mixed diet concept as a viable approach for a reliable assessment of daily intakes, especially for a number of elements such as Cd, Cr, Hg and Mo that occur at low concentrations in individual food products. Simultaneously, stability of some organic nutrients during storage was also investigated. Initial findings suggest that this program may also be useful in the development of reference materials for organic nutrients, for which there is a great need. These aspects are discussed.

Adult↗
PubMed1984

Reference values for elemental concentrations in some human samples of clinical interest: a preliminary evaluation.

Over 60 investigators, some of them with an outstanding international reputation as analysts, were requested to identify reliable data from their countries for elemental concentrations in normal adult human samples of clinical interest by contributing their own data as well as screening the literature information. A set of samples consisting of whole blood and its components, urine, milk, liver and hair were chosen and considered for 15 elements of biological significance: Zn, Cu, Fe, Se, Mn, Pb, Cd, Hg, As, Mo, Cr, Co, I, Ni and F. The results partly cover over 40 countries from the global regions of Africa, Asia, Europe, North, South and Central America, Australia and New Zealand. This survey has been useful in demonstrating certain trends of trace element picture around the world, at least qualitatively. Both diet and environment have a strong influence on the distribution pattern of several elements such as As, Cd, Mn, Pb, Se and Zn. A limited comparison of the available information on soil status of different countries revealed interesting associations for elements such as Mn and Zn. Importantly, this study revealed that only a few countries were in a position to supply a reasonable amount of data on samples requested here. In particular, for a number of countries, reliable data for even very essential elements such as Cu, Zn and Fe were not available. In view of the nutritional importance of several elements the time is ripe for international organizations to intervene and help produce some reference data for selected global regions which lack data of any kind.

Diet↗
PubMed1982

Determination of Co, Cu, Fe, Hg, Mn, Sb, Se and Zn in milk samples.

Concentrations of Co, Cu, Fe, Hg, Mn, Sb, Se and Zn in IAEA milk (dry) standard A-11 were re-evaluated with the help of instrumental and radiochemical neutron activation analysis (NAA). The results show reasonably good agreement for Co (5.1 +/- 0.55 ng/g) and Zn (34 +/- 2.5 micrograms/g), in relation to the recommended values. For Cu (374 +/- 15 ng/g), Fe (2.4 +/- 0.34 microgram/g) and Mn (250 +/- 20 ng/g); the results obtained are lower than the reported values. Cu, Mn, and Zn were cross-checked by atomic absorption spectrophotometry (AAS). The results, Cu = 331 +/- 27 ng/g, Mn = 302 +/- 62 ng/g, and Zn = 35 +/- 1 microgram/g, fall within the range of mean values obtained by NAA. for Hg and Se, using instrumental NAA, only upper limits could be indicated; because of the low levels of concentrations of Hg and Se on one hand, and high content of P (9100 micrograms/g) in A-11 milk standard on the other, NAA coupled with radiochemistry is to be preferred for these two elements. In pooled human milk, in addition to Cu and Mn (radiochemical) and Co, Fe, Sb and Zn (instrumental), Hg and Se could also be determined non-destructively because of the favorable Hg/P and Se/P ratios in this matrix.

Animals↗
PubMed1982

Multielement analysis of fingernail, scalp hair and water samples from Egypt (a preliminary study).

Scalp hair, fingernail and water samples collected from different parts of Egypt are analysed by atomic absorption spectrophotometry and neutron activation analysis. The results for hair show minimum variation of Zn among different regions; a relatively well-controlled dispersion of values (maximum to minimum less than 2) for Co, Fe, Mn and Se; an overall inter-regional variation of factors of 7, 10, 6, 4 and 6 for the elements Ag, Cd, Cs, Sc and W, respectively; a steady decline in the concentration of Sc from south (Aswan) to north (Alexandria). The findings for nail show a steady decline in the concentration of Fe and Sc from south (Aswan) to north (Alexandria); elevated levels of Cd in samples from Aswan area; and regional variations extending up to factors of 6.5, 3.6, 4.7, 5.9, 4.4, 4.5 and 1.9 for Co, Cr, Cs, Mn, Mo, W and Zn, respectively. No unified relationship is observed between the elemental compositions of hair and nail. For Cr, Cs, Fe, Sb and Sc mean values for hair are lower than in nails. Among the remaining elements the ratio nail/hair is less than 1 for Ag in Assiut, El Kharga and Alexandria, for Cd in all of the areas with the exception of Aswan, for Co, Mn and Mo in Cairo, for Zn in Cairo and Alexandria, and for W in Alexandria. The data for water samples reflect highest concentration of all the measured elements in the Mediterranean sea; a steady increase of the concentration of Cu in drinking water from south to north and for Nile water a similar trend for Ca and Mg; and elevated concentrations of Sb and Mn in river water. No distinct trend for the interrelationship between water and tissue elemental concentrations could be established for the regions around Cairo, Aswan and Alexandria.

Egypt↗
PubMed1981

Selenium and myocardial infarction: glutathione peroxidase in platelets.

The activity of the selenoenzyme glutathione peroxidase (EC 1.11.1.9) was determined in platelets of 15 patients with acute myocardial infarction and 13 control subjects. The platelets of the patients had significantly lower activities of the enzyme (P(t) greater than 0.99). This may be related to the pathogenesis of the disease.

Adult↗
PubMed1981

Autopsy sampling and elemental analysis: errors arising from post-mortem changes.

The implication of post-mortem changes such as cell swelling, imbibition and autolysis on the elemental composition of body organs has been studied in rats. Liver has been chosen as an example. Retaining the liver inside the intact dead body for different periods of time at ambient temperature induced significant changes in its weight due to post-mortem tissue degeneration. Livers from animals that were frozen at -15 degrees C also showed significant decreases in weight when they were thawed on the third day. The effect of these changes on the concentrations of various elements depended on the association of the elements with extracellular fluid and intracellular components. For example, concentration of K+ was affected more by the lysis of the cell and sustained losses up to 30 per cent. in relation to the control values, while the total content was reduced by more than 40 per cent. as a result of both lysis and tissue liquefaction. For Na+, differences ranging from +10 to -20 per cent. in concentrations and +20 to -40 per cent. in total content were observed which could be explained by the movement of fluid in and out of the organ. Among trace elements, variation observed for iron ranged from -20 to +40 per cent., while both copper and zinc were found to fluctuate between -20 and +20 per cent. The loss observed in the total content in the liver for the five trace elements studied (Cu, Fe, Mn, Rb and Zn) was found to be about 20 to 40 per cent.

Animals↗
PubMed1981

Concentration differences between serum and plasma of the elements cobalt, iron, mercury, rubidium, selenium and zinc determined by neutron activation analysis.

The differences in concentrations of cesium, cobalt, iron, mercury, rubidium, selenium and zinc between serum and plasma were examined with the aid of instrumental neutron activation analysis. Eighty serum and plasma samples obtained from 13 donors were compared. Serum was prepared in plastic tubes immediately after clotting, and plasma was separated with heparin as anticoagulant. No significant differences in the concentrations of cesium, cobalt, mercury and selenium were observed. However, the concentrations of iron, rubidium and zinc were significantly higher in serum than in plasma. The average differences were 322, 12 and 20 ng/ml for iron rubidium and zinc, respectively. The average differences found for cesium, rubidium and zinc were far below that which can be expected from a complete, or considerable release of these elements from platelets which aggregate or disintegrate during the clotting process in preparing serum.

Cobalt↗