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Biomedical subjects

D Kumar

Publications and source records attributed to D Kumar.

At least 433 records · Page 24Linked to original sources
PubMed1978

Histo-physiology of the salivary glands of the red cotton bug, Dysdercus koenigii (Pyrrhocoridae-Heteroptera)--histological, histochemical, autoradiographic and electron-microscopic studies.

1. Gross morphology, histology, histochemistry and ultrastructure of the salivary glands of Dysdercus koenigii have been studied. The mode of origin of saliva was investigated by tracer techniques. 2. Differences in histological structure of the glandular lobules, consistency and staining properties of the lumen contents, as also in their capability to incorporate materials from haemolymph have been observed, pointing to a possible division of labour among the different parts of the gland. 3. 3H-thymidine experiments showed that some of the nuclei of the gland cells incorporate the label asynchronously, indicating their polyploid growth or repair DNA synthesis or even specific gene amplification. 4. 3H-uridine incorporation patterns showed that the gland cell nuclei are the principal centres of RNA synthesis. The synthetic products move into the cytoplasm and then into the glandular lumen. The RNA exported into the lumen conjugates with the protein to form RNP which provides the material for the formation of the protective sheath around the mandibular, and maxillary stylets at the time of piercing and sucking. 5. Autoradiographic experiments with 3H-L-histidine showed that the site of heavy labelling shifts from outside inwards with progressive incubation times, indicating that the glandular epithelium is capable of transporting haemolymph materials (proteins?) into the lumen. Some of the haemolymph protein fractions could possibly be used as the precursors of salivary components, in addition to the endogenously synthesised materials. 6. Salivary histochemical studies revealed the presence of glycogen both in the lumen and in the granular epithelium. 3H-glucose labelling patterns are in agreement with the histochemical localization of glycogen and suggest that the blood sugar (trehalose) might be appropriated by the gland cell epithelium for the formation of glycoproteins. 7. Ultrastructural observations of the gland cells showed that the basal borders of the cells are highly folded to form pits. Pinocytotic uptake of the haemolymph materials may be facilitated by these pit formations. The apical borders of the cells facing the lumen develop numerous microvilli and the secretion granules escape into the lumen by pinocytosis, as revealed also by the autoradiographic studies with tritiated histidine. The distribution of golgi vesicles, mitochondria, microtubules is not uniform. They tend to show a higher density towards the apical border than towards the basal border of the cells. This difference may be related to the well-known functions of these organelles in packing the secretion products and to provide energy and channels for their transport. The rER exists in the form of numerous vesicles scattered evenly throughout the cytoplasmic space. But they also exist as stacks of membranes. Their proximity with golgi vesicles seems to be significant for the packing process of the secretion products.

Animals↗
PubMed1977

Anti-insulin IgE in diabetics.

Anti-insulin IgE and IgG were estimated in sera of diabetic patients. Using a paper radioimmunosorbent technique, detectable titers of anti-insulin IgE were found in all insulin-treated diabetics who were non-allergic to insulin. Patients with generalized insulin allergy, and immune-type insulin-resistance had higher titers of anti-insulin IgE. Anti-insulin IgG was present in all insulin-treated patients. The titers were significantly higher in insulin-resistant diabetics. Four of the 12 cases with insulin allergy had undetectable anti-insulin IgG titers. The ratios of 125I-insulin bound by IgE and IgG were significantly higher in 11 (91%) patients with systemic insulin-allergy. It is suggested that a relative excess of anti-insulin IgE may be associated with the insulin allergic state.

Adult↗
PubMed1976

Qualitative analysis of the performance of introverts and extraverts on Standard Progressive Matrices.

The present study was designed to bring out the differences between extraverts and introverts on Standard Progressive Matrices. A group of 100 subjects of equal number of sexes were given a qualitative analysis of their performance on SPM. The study brought out the initial superiority of extraverts over introverts. But with passage of time and increase in difficulty level the introverts did significantly better as shown both by the t-ratios and the F-ratios. Personality interacted with sex to yield differences in performance of wrong scores only. These findings were discussed in terms of arousal, cortical excitation and reactive inhibition.

Achievement↗