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Biomedical subjects

S Chandra

Publications and source records attributed to S Chandra.

At least 181 records · Page 10Linked to original sources
PubMed1991

Extramedullary hematopoiesis in the liver in sudden infant death syndrome.

Liver extramedullary hematopoiesis was examined in 54 victims of sudden infant death syndrome and in 21 infants who died of other causes in an attempt to confirm Naeye's findings of increased extramedullary hematopoiesis in cases of sudden infant death syndrome. Our data showed greater extramedullary hematopoiesis in victims of sudden infant death syndrome (F = 23.52), supporting Naeye's hypothesis that victims of sudden infant death syndrome have suffered a subtle, chronic hypoxemic condition before death.

Aging↗
PubMed1990

Inhibition of plant calcium-dependent protein kinases by basic polypeptides.

Wheat embryo Ca2+-dependent protein kinase (CDPK) is inhibited by a variety of polypeptides including actin, gramicidin S, melittin, protamine, various histone preparations, histone H4 and by basic amino-acid homopolymers. Melittin (Ki 9 microM) is a non-competitive inhibitor of wheat germ CDPK and also inhibits wheat leaf CDPK and silver beet leaf CDPKs. Protamine inhibits wheat germ CDPK in an apparently competitive fashion (Ki 0.2 microM) and is also a potent, albeit less effective, inhibitor of the leaf CDPKs. Various basic amino-acid homopolymers are also potent, apparently competitive inhibitors of wheat embryo CDPK, namely poly(L-lysine) (IC50 2 nM), poly(L-ornithine) (IC50 3 nM) and poly(L-arginine) (IC50 17 nM) and also inhibit the leaf CDPKs, albeit at higher concentrations. Histone H4 and various calf thymus histone preparations inhibit wheat embryo CDPK in a fashion that is not competitive and calmodulin can substantially reverse such inhibition.

Hydrogen-Ion Concentration↗
PubMed1990

Pulp calcifications in primary teeth.

Information regarding the prevalence of pulp calcifications in primary teeth is lacking. The occurrence of pulp calcifications in 120 primary maxillary and mandibular extracted teeth was evaluated radiographically. Twenty-five percent of second molars presented evidence of pulp calcifications; approximately 3% of central incisors were calcified. No other categories of teeth displayed pulp involvement. The low occurrence of pulp calcifications in primary teeth support the view that the occurrence of pulp calcification increases with age.

Age Factors↗
PubMed1990

Ion microscopic imaging of calcium transport in the intestinal tissue of vitamin D-deficient and vitamin D-replete chickens: a 44Ca stable isotope study.

The intestinal absorption of calcium includes at least three definable steps; transfer across the microvillar membrane, movement through the cytosolic compartment, and energy-dependent extrusion into the lamina propria, Tracing the movement of calcium through the epithelium has been hampered by lack of suitable techniques and, in this study, advantage was taken of ion microscopy in conjunction with cryosectioning and use of the stable isotope 44Ca to visualize calcium in transit during the absorptive process. The effect of vitamin D, required for optimal calcium absorption, was investigated. Twenty millimolar 44Ca was injected into the duodenal lumen in situ of vitamin D-deficient and vitamin D-replete chickens. At 2.5, 5.0, and 20.0 min after injection, duodenal tissue was obtained and processed for ion microscopic imaging. At 2.5 min. 44Ca was seen to be concentrated in the region subjacent to the microvillar membrane in tissue from both groups. At 5.0 and 20.0 min, a similar pattern of localization was evident in D-deficient tissues. In D-replete tissues, the distribution of 44Ca became more homogenous, indicating that vitamin D increased the rate of transfer of Ca2+ from the apical to the basolateral membrane, a function previously ascribed to the vitamin D-induced calcium-binding protein (28-kDa calbindin-D). Quantitative aspects of the calcium absorptive process were determined in parallel experiments with the radionuclide 47Ca. Complementary information on the localization of the naturally occurring isotopes of calcium (40Ca) and potassium (39K) is also described.

Animals↗
PubMed1990

Relation of salivary phosphorus and alkaline phosphatase to the incidence of dental caries in children.

The phosphorus concentration and alkaline phosphatase activity in saliva may be related to the susceptibility to dental caries and supragingival calculus. Hence, the unstimulated mixed saliva of child patients were assayed by biochemical methods to determine the phosphorus concentration and alkaline phosphatase activity in such salivary samples. It is very interesting to note that higher phosphorus concentration and alkaline phosphatase activity were found in patients with rampant caries as compared to that with non rampant/control group.

Adolescent↗
PubMed1990

Cross-sectional study to evaluate variations in attached gingiva and gingival sulcus in the three periods of dentition.

The dimensional differences of the attached gingiva and gingival sulcus in the primary, mixed and permanent dentition were studied clinically in normal gingivae of 382 children, aged 4-15 years. The depth of the gingival sulcus and the width of keratinized gingiva were also measured. Shallow gingival sulcus was observed in the primary dentition as compared to that in permanent dentition. However, in the mixed dentition deeper sulcus was observed around the newly erupted teeth. This was attributed to deeper penetration of the instrument, at the time of eruption. The widest zone of attached gingiva was observed in maxillary and mandibular incisors, decreasing gradually over the cuspids and first premolars (first primary molars), and again attached gingiva increased in second premolars (second primary molars) and first and second permanent molars. The width of attached gingiva in case of newly erupted permanent teeth (mixed dentition) was narrower in the corresponding primary teeth. This was due to an increase in the gingival sulcus depth. The attached gingiva increased in width with age. This was related to a concomitant reduction in sulcus depth.

Adolescent↗
PubMed1990

The effect of metronidazole on the anaerobic microorganisms of the root canal--a clinical study.

The antibacterial effect of 0.25% metronidazole solution as root canal irrigant on anaerobic bacteria was studied in ten central incisors. Each tooth was treated at four appointments, and the presence of anaerobes in the root canal was studied on each occasion. No antibacterial intracanal dressings were used between the appointments. No anaerobes could be recovered from any tooth on the fifth appointment. In the control group, where normal saline was used as an irrigant, anaerobes could be recovered in four of the ten canals. These results suggest that 0.25% metronidazole solution is more effective than saline solution as a root canal irrigant.

Adolescent↗
PubMed1990

Antimalarial activity of some 4-alkylamino 2/3 methoxy-4-aminodiphenyl sulphones.

From a series of thirty six 2,3, N-substituted 4,4'-diaminodiphenyl sulphones studied for their suppressive activity in mice against blood induced erythrocytic stage of Plasmodium berghei infection, six sulphones (1-6) showed 100% suppressive and curative activity at an intraperitoneal dose of 1 mg/kg x 4 days. These sulphones have been studied for their suppressive activity in still lower doses ranging from 1.0-0.25 mg/kg i.p. x 4 days and for their curative activity at 1 mg/kg i.p. x 4 days in comparison to DDS as standard drug. The maximum tolerated dose of these compounds and DDS has also been determined. These sulphones have better therapeutic efficacy for their suppressive and curative action than DDS.

Animals↗
PubMed1990

HBV & HIV seropositivity in multi-transfused haemophilics & thalassaemics in eastern India.

Seropositivity to HBV (HBsAg) in multi-transfused patients of haemophilia A, haemophilia B, B thalassaemia and EB thalassaemia from Eastern India, was found to be 9, 0, 22.1 and 13 per cent respectively. HIV seropositivity was detected in patients of haemophilia A (4.4%) and B thalassaemia (0.8%) who received plasma components and packed cells periodically. Seropositivity to both HBsAg and HIV was found in one patient of haemophilia A. Serum alanine amino transferase (ALT), raised in multi-transfused thalassaemics suggests concurrent hepatitis which might have enhanced the transmission of viruses due to disturbed immune status. The universal voluntary blood donation programme, screening of blood for HBV and HIV by sensitive tests, early immunisation and periodic monitoring of HBV and HIV status are prerequisites for the management of transfusion dependent thalassaemia and haemophilia.

Blood Transfusion↗
PubMed1990

Pulp calcifications in primary teeth.

One hundred and twenty primary maxillary and mandibular extracted teeth were collected to study the occurrence and nature of pulp calcifications. The teeth were serially sectioned, stained with hematoxylin and eosin, examined by light microscope. Pulp calcifications were observed in 31 (25.8%) teeth. Two types of pulp calcifications were noticed i.e., diffuse calcifications and free/attached type denticles. The occurrence of pulp calcification appears identical in all teeth except in the first primary molar which is statistically not significant (P greater than 0.05). The low prevalence of pulp calcifications in the primary teeth support the view that pulp calcification increases as the age advances.

Dental Pulp Calcification↗
PubMed1989

Quantitative imaging of boron, calcium, magnesium, potassium, and sodium distributions in cultured cells with ion microscopy.

A method for the conversion of intensity information in ion micrographs of freeze-fractured, freeze-dried cultured cells to local dry weight elemental concentrations is presented. Homogenates generated from cultured cells are used as calibration standards. Ion microscope (IM) relative sensitivity factors for B, Ca, K, Mg, and Na with respect to the matrix element C are determined by the correlation of IM and inductively coupled plasma atomic emission spectrometry analyses of the cellular homogenates. After calibration of the IM imaging system, the relative sensitivity factors are used to determine local intracellular concentrations of B, Ca, K, Mg, and Na in cultured Swiss 3T3 fibroblasts. Intracellular B was introduced through cellular uptake of Na2B12H11SH, a candidate therapeutic agent for boron neutron capture cancer therapy. The IM intracellular concentration results show good agreement with published electron probe X-ray microanalysis results. Estimated detection limits are in the low- to subparts-per-million dry weight concentration range.

Animals↗
PubMed1989

Inhibition of oxidative phosphorylation by organotin thiocarbamates.

A series of triphenyl-, tricyclohexyl- and tribenzyltin compounds have been synthesized and examined as inhibitors of mitochondrial oxidative phosphorylation. All compounds tested inhibit oxidative phosphorylation linked to succinate oxidation by potato tuber mitochondria. All of the organotin compounds inhibit ADP-stimulated O2 uptake linked to succinate oxidation with concentrations for 50% inhibition in the range 2-50 microM. This inhibition is not due to inhibition of electron transport from succinate to O2 per se: none of the organotin compounds at 50 microM substantially inhibit the rate of succinate oxidation in the presence of 2,4-dinitrophenol. Representative organotin compounds at 0.5-50 microM do not act as uncouplers of succinate oxidation. It is concluded that the organotin compounds act as energy transfer inhibitors to inhibit oxidative phosphorylation in potato tuber mitochondria. A similar mode of action of representative organotin compounds was found with rat liver mitochondria. These organotin compounds inhibit a hydrophobic Ca2+-dependent plant protein kinase in the absence but not in the presence of thiols.

Animals↗