Biomedical subjects
Publications and source records attributed to A Trivedi.
A great deal of progress has been made in elucidating the underlying mechanisms which control the interplay between the nuclear and mitochondrial genomes during biogenesis of mitochondria. The advantage of using the yeast Saccharomyces cerevisiae in these studies over other eukaryotic cells will be discussed.
A 1.5- to 3.5-fold accumulation of phosphatidylserine was observed when Candida albicans and Saccharomyces cerevisiae cells were grown in the presence of hydroxylamine, a known inhibitor of phosphatidylserine decarboxylase. However, as compared to S. cerevisiae cells, the levels of phosphatidylcholine and phosphatidylethanolamine were much lower in C. albicans cells. The enrichment of phosphatidylserine selectively affected the transport of several amino acids.
Individual phospholipids were assayed in exponentially growing and G1-arrested temperature-sensitive cell division cycle (cdc) mutants of Saccharomyces cerevisiae. It was observed that cdc28 cells which are known to arrest at 'start' when shifted to their non-permissive temperature, resulted in a 40% decrease in phosphatidylinositol (PI) level while the phosphatidylserine (PS) content was doubled in these cells. The reduced level of PI was restored in cdc4 and cdc7 mutants which are known to arrest past the 'start'. The increase in PS level in cdc28 mutant which was probably to compensate the intrinsic charging of membrane environment, was also reduced in cdc4 and cdc7 mutants. Our results demonstrate that PI may play a role in yeast cell division and growth and that the abnormalities of cdc28 could also be related to PI decrease.
In contrast to Saccharomyces cerevisiae cells, the supplementation of the growth media of Candida albicans cells with choline did not result in PC enrichment. The level of accumulation of choline uptake, which is the first step of its utilisation was found to be 50% higher in S. cerevisiae cells. However, the activity of choline kinase (EC 2.7.1.32), the first enzyme in CDP-choline pathway was identical between the two cell types. It appears that CTP: phosphocholine cytidylyl-transferase (EC 2.7.7.15) may be the regulatory enzymatic step in overall PC biosynthesis of C. albicans cells.
The phospholipid composition of yeast plasma membrane was manipulated by two different methods: (i) by using two auxotrophic strains KA101 (cho1) and MC13 (Cho+) which required phospholipid bases for growth and (ii) by supplementing Saccharomyces cerevisiae (3059) cells with high concentration of choline or ethanolamine. It was possible to enrich the plasma membrane with phosphatidylcholine (PC) or phosphatidylethanolamine (PE) by both methods. The uptake of amino acids, e.g., glycine, glutamic acid, leucine, lysine methionine, phenylalanine, proline and serine, was significantly reduced in PC- or PE-enriched cells. However, the extent of reduction in transport was variable among different strains. A fluorescent probe, 1-anilino-8-naphthalene sulfonate (ANS), was used to monitor the structural changes induced by altered phospholipid composition. It was observed that the relative fluorescence intensity of bound ANS was decreased as a consequence of PC or PE enrichment. The decrease in fluorescence was probably associated with reduced number of available binding sites (n) and increased apparent dissociation constant (Kd). Furthermore, our results also suggest that a critical level of PE or PC is required for proper functioning of yeast membrane.
A decrease in the influx of several amino acids was observed following gamma-irradiation. At low dose (2.5 Gy), which does not affect cell survival, a stimulation in the uptake was visible; moreover, sulphydryl loss and lipid peroxidation were also evident. With further increase in the dose of radiation, a parallel increment in the loss of sulphydryl groups and production of malonaldehyde was observed. Radioprotectors like L-cysteine and dithiothreitol were shown to shield the radiation-induced loss of sulphydryl and damage to transport and survival. Reduced glutathione, on the other hand, exhibited protection at the level of sulphydryl damage only. N-ethylmaleimide, a well known hypoxic cell radiosensitizer, enhanced the radiosensitivity with respect to survival; it, however, had no effect on amino acid transport. Oxygen enhancement of radiation damage to transport and cell survival and the radioprotection by sodium formate under these circumstances, and more so by anoxia, were demonstrated. The results indicate that the manifestation of damage to membrane structure and function precedes any observable loss of survival.
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Thirty-six mentally retarded adolescents were administered the Wechsler Intelligence Scale for Children (WISC), the Peabody Picture Vocabulary Test (PPVT), and the Slosson Intelligence Test (SIT) to determine reliability and comparable performance among the three intelligence tests. Correlations as a function of IQ and MA, by sex, were computed among the three tests. All were significant (p less than .01), but the WISC and SIT had consistently higher relationships than any other comparisons on both IQ and MA. Analyses also indicated that the PPVT produced higher IQ scores than the WISC or SIT and that MA in the PPVT was influenced by the previous administration of the SIT. It was concluded that, as a screening device, the SIT is more reliable and approximates WISC scores more consistently than the PPVT.
ESR spectrometry of sugars and biological samples is being evaluated for emergency personnel dosimetry. Sugars are near tissue-equivalent, universally available in pure form and produce a simple, reproducible, low background signal. Of the sugars tested, sucrose and dextrose are the most sensitive and the ESR signals are proportional to X- or gamma-ray doses over the range of 0.5-10 Gy. There is little dependence on radiation energy or dose-rate, and the ESR signals remain stable for long periods post-irradiation. Human hair samples show considerable variability and signal complexity creating difficulties in dose assessment.
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OBJECTIVE: To compare tuberculin screening of all kindergartners and high school entrants (screen-all strategy) vs screening limited to high-risk children (targeted screening). DESIGN: Decision, cost-effectiveness, and cost-benefit analyses. SETTING AND SUBJECTS: Students in a large urban and rural county. DEFINITIONS: High risk of tuberculosis infection was defined as birth in a county with a high prevalence of tuberculosis. Low risk was defined as birth in the United States. OUTCOME MEASURES: Tuberculosis cases prevented for 10, 000 children screened. Net costs, net cost per case prevented, benefit-cost ratio, and incremental cost-effectiveness. RESULTS: The screen-all strategy would prevent 14.9 cases per 10,000 children screened; targeted screening would prevent 84.9 cases per 10,000 children screened. The screen-all strategy is more costly than no screening; the benefit-cost ratio is 0.58. Targeted screening would result in a net savings; the benefit-cost ratio is 1.2. Screening all children is cost saving only if the reactor rate is 20% or greater. The cost per additional case prevented for screening all children compared with targeted screening (+34 666) is more than twice as high as treatment and contact tracing for a case of tuberculosis (+16 392). CONCLUSIONS: Targeted screening of schoolchildren is much less costly than mass screening and is more efficient in prevention of tuberculosis.
This study deals with results of coronary artery reoperations in 21 males aged 54.4 +/- 6.6 years. Native vessel coronary disease at first and second operation was nearly the same (2.7 +/- 0.6 vs 2.8 +/- 0.4 vessel, p = NS). Graft attrition and deterioration in left ventricular ejection fraction (55.9 +/- 9.2 initial vs 36 +/- 15 at reoperation, p < 0.001) necessitated reoperation in majority. Recurrence of angina (71%) and left ventricular failure (23.8%) were the clinical indicators for reoperation. Procedure was successful in 20 (95%) and had to be abandoned in 1 due to severe pericardial and sternal adhesions. Arterial grafts were utilised in 90% (18 cases, Group A and B). Total arterial revascularisation (Group A) was done in 9 (45%) using Y graft 6, combination of both mammary arteries 2, and by both mammary and inferior epigastric artery in 1. Group B patients had arterial grafts (bilateral IMA 1, Y graft 1, bilateral IMA + gastroepipolic 1, RIMA 4, and LIMA 2) in addition to a venous graft. Two patients (group C, 10%) had only venous grafts. There was no in hospital mortality or morbidity and at 10 +/- 5.2 months follow up, all are asymptomatic with negative stress test at 3 months followup in 8 cases. We conclude that coronary artery reoperations using arterial conduits can be performed safely with excellent immediate and early results.
Pulmonary function tests, arterial blood gas tensions and morbidity were compared in 50 patients undergoing coronary artery bypass graft surgery. Thirty patients had bilateral internal mammary grafts (Group 1), 5 patients had only saphenous vein grafts (Group 2) and 15 patients had a single arterial graft in addition to vein grafts (Group 3). Pleural effusion and wound infection were more common in patients with internal mammary artery grafts (p < 0.05). Patients in Group 2 required prolonged ventilation but this could be related to their underlying left ventricular dysfunction. Patients in all the three groups developed a severe restrictive ventilatory defect in the postoperative period and the degree of impairment was maximum in Group 1 patients (p < 0.01). These patients also had evidence of small airway obstruction. Thus an overall decrease in pulmonary function occurs in the postoperative period by 30 to 40% (p < 0.001). The derangement is greater in patients with arterial grafts, as a result of impaired blood supply, increase in pleural drains and additional surgical trauma secondary to mobilization of internal mammary arteries leading to delayed recovery. The awareness of these findings can be of great value in postoperative management of these patients. In addition, these observations should also be kept in mind while planning the choice of grafts in a patient undergoing coronary artery bypass graft surgery.
Three patients with left ventricular pseudoaneurysm are presented. Two patients had inferior and one had an anterolateral wall Q wave myocardial infarction. Echocardiography with Doppler colour imaging provided the diagnosis in one case, whereas the correct diagnosis was possible on left ventriculography in all. Successful surgery using patch closure of the defect in all patients and bypass grafting of the diseased coronary vessels was done in 2 cases. Angiographic follow-up in one case revealed excellent result and during 18 to 30 months of clinical follow-up, all patients are asymptomatic.
Eosinophilic enteritis or gastroenteritis is a rare disease characterised by tissue eosinophilia which can affect different layers of bowel wall. It can affect any area of gastrointestinal tract from the esophagus to the rectum, although stomach and small intestine are sites most frequently reported. It is important to recognize this disease early and institute the necessary treatment. An eight year old girl presented with acute intestinal obstruction. Exploration revealed a structure of proximal jejunum. Histopathology demonstrated eosinophilic jejunitis. The case is reported owing to this rarity and relevant literature is reviewed.