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Biomedical subjects

S Chandra

Publications and source records attributed to S Chandra.

At least 361 records · Page 20Linked to original sources
PubMedDate not supplied

Direct current conductivity studies on poly(3-methyl thiophene).

The direct current (DC) conductivity of poly(3-methyl thiophene) was measured in the temperature range of 77-300 K. The observed DC conductivity data were analyzed in the light of Mott's variable range hopping model. Different Mott's parameters such as characteristic temperature (T0), average hopping distance (R), average hopping energy (W), and density of states at the Fermi level (N [E(F)]) were evaluated. By taking the inverse of the coefficient of exponential decay of the localized states involved in the hopping process as 0.5 nm, a realistic value of density of states at the Fermi level (N [E(F)]) was obtained that agrees well with the values reported earlier for other conjugated polymers.

Chlorides↗
PubMedDate not supplied

Oncologic applications of biophotonics: prospects and problems.

The understanding of various intrinsic photobiophysical processes has prompted researchers to develop different types of biodevices for health care. In the recent past, because of extensive contributions from various groups in the field of biophotonics, several important biomedical applications are emerging in the fields of both diagnostics and therapy. In this brief review, we discuss a few specific applications related to early detection and characterization of premalignant and malignant lesions using optical spectroscopic techniques, namely, fluorescence and Raman, and in management of cancer, the emerging scene of photodynamic therapy.

Humans↗
PubMedDate not supplied

Soluble substituted poly-p-phenylenes--a new material for application in light-emitting diodes: synthesis and characterization.

Poly-p-phenylenes have attracted a great deal of attention with respect to their applications in displays, light-emitting devices, and batteries. However, the polymer poly-p-phenylene obtained by the Kovacic method is insoluble and intractable. The present study reports the preparation of soluble poly(p-phenylenes) by polymerization of derivatives of benzene in the presence of a specific aromatic nuclei. The resultant copolymer so obtained is soluble in common organic solvents such as chloroform and toluene. Preliminary studies have indicated that the polymer shows orange photoluminescence and electroluminescence when a potential of 7-10 V is applied to the device.

Chloroform↗
PubMedDate not supplied

Clinical aspects of adhesive intestinal obstruction.

BACKGROUND: Mechanical intestinal obstruction remains one of the commonest surgical emergencies. With hernias being electively repaired and obstructive hernias becoming less common, adhesive obstruction has emerged as the leading cause of intestinal obstruction in the west. This study was designed to analyse any such changes in the pattern of intestinal obstruction in the population of Pondicherry of Tamilnadu of South India. METHODS: Data were collected from the compiled case records at JIPMER, Pondicherry, both retrospectively and prospectively from 1984 to 1992 about the clinical aspects of intestinal obstruction and analysed. RESULTS: There were 572 patients admitted with a diagnosis of intestinal obstruction in this period. Obstructed external hernia occurred in 219 patients and adhesive obstruction in 176 patients. Fourteen percent of the patients with adhesive obstruction had appendicectomy as the index laparotomy in the past. Majority of the patients presented within 10 years of the index laparotomy. Adhesive obstruction was managed mainly by conservative treatment in 109 cases. There were 25 patients with recurrent obstruction; most of them were conservatively managed. CONCLUSIONS: Obstructed external hernias were the commonest cause of intestinal obstruction. Increasing the patient awareness will help to decrease the incidence of obstructed hernias significantly. Adhesive obstruction deserves a conservative approach with judicious application of surgical intervention. A careful approach is required to avoid the increased morbidity and mortality associated with delay in the diagnosis of gangrenous obstructions.

Adolescent↗
PubMedDate not supplied

Dynamic SIMS ion microscopy imaging of intracellular boron accumulation from carboranyl nucleosides in glioma cells.

BACKGROUND: Selective accumulation of boron-10 isotope in the nuclei of cancer cells is pivotal to the success of Boron Neutron Capture Therapy (BNCT). Sophisticated microanalytical techniques are needed for checking the selectivity and boron delivery characteristics of experimental BNCT drugs. The present study employs a secondary ion mass spectrometry (SIMS) based subcellular isotopic imaging technique of ion microscopy for testing four carboranyl nucleosides. MATERIALS AND METHODS: CDU, HMCDU, CTU, and CFAU were tested for their boron delivery to the nuclear and cytoplasmic compartments of U251 human and F98 rat glioma cells. Quantitative SIMS analysis of boron was carried out in cryogenically prepared cells. RESULTS: For all drugs, the cell cytoplasm revealed significantly higher boron than the nucleus. However, the boron partitioning between the cell nucleus and the nutrient medium indicated 6.4-10.6 times higher boron in the nucleus. CONCLUSION: Carboranyl nucleosides studied here may provide efficient BNCT agents and need further evaluations of their efficacy.

Animals↗
PubMedDate not supplied

Identification of risk factors for specific subsites within the oral and oropharyngeal region--a study of 647 cancer patients.

Studies on site specific risks for oral cancers are few. Present investigation explores the possible role of human sociodemographic factors in causing oral cancer. Majority of patients had poor oral hygiene (85.5%) and belonged to 51-60 years age group (35.7%). Most of the subjects were agriculture workers (30.3%). Tongue and floor of mouth included majority of the affected sites (77.2%). Male to female ratio was highest for tonsil (32.3%) but differed marginally for other subsites. Majority of females used tobacco (81%) while males users of tobacco, alcohol and smoking reported in nearly equal proportions. Tobacco and smoking were found as primary risk factors for several intraoral subsites. However, for tongue, palate and lip no risk factor could be identified from given patients' characteristics. In general, tobacco posed high risk for buccal mucosa and alveolus in comparison to other subsites. Smoking affected tonsil and floor of mouth more than other sites. Alcohol posed more risk for buccal mucosa and floor of mouth than tongue.

Adult↗
PubMedDate not supplied

Transendoscopic fine needle aspiration cytology in the diagnosis of hepatocellular carcinoma.

This report describes the use of transendoscopic fine needle aspiration cytology in the diagnosis of three cases of hepatocellular carcinoma who had presented with large nodular liver and mass impression on the left border of the stomach at endoscopy. Using a 21G, 1.0 cm needle catheter, transendoscopic fine needle aspiration was done under direct endoscopic vision. The aspirate confirmed the diagnosis of hepatocellular carcinoma in all of them.

Biopsy, Fine-Needle↗
PubMedDate not supplied

Smoking habits of the medical students.

Smoking habits of the medical students, both undergraduates and postgraduates, were evaluated by self-administering a predesigned proforma. 854 (66.05%) of the 1293 students responded, of whom, 30.7% of them were smokers. The number of smokers and the intensity of smoking increased with the advancement of their career at college. There were more smokers amongst the married and those with a history of smoking in their family. There was no systematic correlation between the socio-economic or rural/urban background and the smoking habit.

Family↗
PubMedDate not supplied

Association of plasma lipoproteins with angiographically defined coronary artery disease.

Lipoprotein (a) and other lipoprotein variables have been correlated with angiographic severity of coronary artery disease. However, pattern of lipoprotein (a) distribution in various racial groups has been found to be different. To study this relationship in the Indian patients, plasma levels of lipoprotein (a) and other lipoprotein variables were examined in 144 consecutive patients undergoing coronary angiography. Total cholesterol and cholesterol content of various lipoproteins were assayed by chemical methods, and in 116 patients lipoprotein (a) was detected by gel electrophoresis. Lipoprotein (a) was positive in a total of 78 (67%) patients, and its positivity in the four angiographic groups with normal coronaries, single vessel, double vessel, and triple vessel disease was 69, 78, 61 and 67 percent respectively. Interestingly, lipoprotein (a) greater than 75 percentile tended to be more frequent in patients with increasing severity of coronary artery disease: 15%, 21%, 25% and 28% in the four groups, respectively. However, this was not statistically significant. Plasma levels of total cholesterol, cholesterol content of other lipoproteins and triglycerides were not significantly different in these four groups of patients. This study, therefore, shows that there is no significant correlation of lipoprotein (a) positivity with angiographic severity of coronary artery disease in our group of Indian patients, although higher values are more frequently present in patients with severe disease.

Coronary Angiography↗
PubMedDate not supplied

Enalapril for prevention of restenosis after coronary angioplasty.

We have evaluated the effect of enalapril in the prevention of restenosis after percutaneous transluminal coronary angioplasty by a randomized trial conducted on 95 patients. The treatment group (n = 46) received enalapril 10 mg/day besides aspirin with calcium blockers, beginning 24 hours before coronary angioplasty. The conventional medical treatment group (n = 49) received only aspirin and calcium blockers. Enrollment required the presence of angina pectoris and successful dilatation of all significant coronary narrowings. All patients were followed up for at least 6 months. Restenosis was identified by symptoms and exercise testing and confirmed by angiography. The incidence of angiographic restenosis was 34% in the enalapril group and 31% in the conventional treatment group. Long term angiotensin converting enzyme inhibition with enalapril in a dose of 10 mg per day does not prevent restenosis after coronary angioplasty.

Adult↗