Biomedical subjects
Publications and source records attributed to S Chandra.
83.41% specimens of Common Myna were found infested with one to four species of Mallophaga, during the year 1984. Incidence of infestation and the indices were higher during the summer months and lower during winter months. The reasons of seasonal abundance are also discussed. Temperature seems to be one of the factors. The seasonal changes in population were found corresponding to the gonadal cycle of the host.
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A deletion of the long arm of chromosome 9(pter----q32:) in a newborn infant at 38 weeks of gestation was associated with a syndrome of arrhinencephaly, rudimentary ears, hypoplastic lungs and ureters, redundant nuchal skin folds, and congenital heart defects. Other findings included a Sydney line, macrocephaly, talipes equinovarus, oligohydramnios, and amnion nodosum. Detailed pathologic observations and the chromosome abnormality are described.
SIMS matrix effects (mass interferences, sputter yield variations and practical ion yield variations) were evaluated in freeze-fractured, freeze-dried cultured cells at the approximately 0.5 micron spatial resolution of the Cameca IMS-3f ion microscope. Cell lines studied include normal rat kidney (NRK), 3T3 mouse fibroblast, L6 rat myoblast, chinese hamster ovary (CHO) and rat kangaroo kidney (PtK2) cells. High mass resolution studies indicated that the secondary ion signals of H-, C-, O-, Na+, Mg+, CN-, P-, S-, Cl-, K+ and Ca+ were free from major mass interferences. However, a large mass interference was observed for nitrogen at mass 14. No significant sputtering yield difference between the nuclear and cytoplasmic compartments of the cells studied was observed. The subcellular distributions of the major (H, C, N and O) and minor (P, S, K, Cl, Na, Mg and Ca) matrix elements were found to be largely homogeneous with the exception of Ca, which was observed mainly in the cell cytoplasm. Practical ion yield variations were compared by three different approaches: (i) by the use of cells doped with known electrolyte concentrations, (ii) by quantitative ion implantation, and (iii) by analysis of the same cell with both electron probe and ion microscope. Each approach indicated an absence of significant practical ion yield differences between the nuclear and cytoplasmic regions of these specimens. These observations indicate that secondary ion signals in this type of sample are not significantly affected by local matrix effect variations. Hence, qualitative imaging of such specimens provides a true representation of subcellular elemental distributions. These observations should allow the development of quantitative ion imaging methodologies and enhance the applicability of ion microscopy to biomedical problems.
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The growing long bones from normal embryonic chicks and young rats have been examined in situ by imaging ion microscopy, a highly sensitive technique for elemental detection and localization. In tibial diaphyses from chick and rat, treated with anhydrous ethylene glycol, embedded in Spurr medium, and dry sectioned 1-2 microns thick, analyses revealed the presence of silicon, calcium, magnesium, carbon, and oxygen. Silicon localization was principally extracellular in the tissues. Comparison of single element maps of silicon and calcium indicated that silicon specifically appeared in putative uncalcified osteoid regions of tibiae. Detection and imaging of silicon by ion microscopy support results of earlier work by Carlisle, who demonstrated the element in osteoid of rat and mouse bone by electron probe microanalysis. The current data offer the possibility for characterizing more completely silicon interaction in vertebrate calcified tissues.
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A freeze-fracture methodology was standardized for tissue culture cells to study intracellular distribution of diffusible elements with ion microscopy. Chinese hamster ovary (CHO) and normal rat kidney (NRK) cells grown on a silicon substrate were sandwiched using another smooth surface (silicon, glass, mica) in the presence of spacers and fast frozen in liquid nitrogen slush. The sandwich was fractured by prying the two halves apart under liquid nitrogen. This procedure produced large areas on the silicon substrate containing hundreds of cells grouped together and fractured at the apical cell surface. After freeze-drying, these cells revealed a subcellular distribution of Na, K, Ca, Mg, P, Cl and S with the approximately 0.5 micron lateral resolution of the ion microscope. Between the nuclei and the cytoplasm of cells, no major differences were observed for Na, K, Mg, P, Cl and S intensities. Calcium alone, however, exhibited a remarkable distribution. Calcium accumulated more in the cytoplasm than in the nuclei of cells. Even within the cytoplasm its distribution was heterogeneous, suggesting Ca binding sites. The fractured cells consistently exhibited high K-low Na intensities. The injured or dead cells were easily recognized among the healthy ones due to their abnormal ion composition. This simple freeze-fracture methodology allowed fracturing of cells without removing the cells from the substrate. In addition, it eliminated the need for washing the nutrient media away and cryo-sectioning before ion microanalysis. The methodology was successfully extended to 3T3 mouse fibroblast, PtK2 rat kangaroo and L5 rat myoblast cultures.
The immune system plays a key role in the body's ability to fight infection and reduce the risk of developing tumors, autoimmune and degenerative disease. Nutritional deficiencies and excesses influence various components of the immune system. Early studies investigating the association between nutrition and immunity focused on generalized protein-energy malnutrition, particularly in children in developing countries. The extent of immunological impairment depends not only on the severity of malnutrition but on the presence of infection and on the age of onset of nutritional deprivation, among other factors. In industrialized nations, immune function has been shown to be compromised in many malnourished hospitalized patients, small-for-gestational age infants, and the elderly. Obesity also may adversely influence immune function. Imbalances of single nutrients are relatively uncommon in humans, and investigations of protein and amino acids and specific vitamins, minerals, and trace elements generally are carried out in experimental animals. Deficiencies of protein and some amino acids, as well as vitamins A, E, B6 and folate, are associated with reduced immunocompetence. In contrast, excessive intake of fat, in particular polyunsaturated fatty acids (e.g. linoleic and arachidonic acids), iron, and vitamin E are immunosuppressive. Trace elements modulate immune responses through their critical role in enzyme activity. Both deficiency and excess of trace elements have been recognized. Although dietary requirements of most of these elements are met by a balanced diet, there are certain population groups and specific disease states which are likely to be associated with deficiency of one or more of these essential elements. The role of trace elements in maintenance of immune function and their causal role in secondary immunodeficiency is increasingly being recognized. There is growing research concerning the role of zinc, copper, selenium, and other elements in immunity and the mechanisms that underlie such roles. The problem of interaction of trace elements and immunity is a complex one because of the frequently associated other nutritional deficiencies, the presence of clinical or subclinical infections which in themselves have a significant effect on immunity, and finally the altered metabolism due to the underlying disease. There are many practical applications of our recently acquired knowledge regarding nutritional regulation of immunity.(ABSTRACT TRUNCATED AT 400 WORDS)
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