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Biomedical subjects

V Gupta

Publications and source records attributed to V Gupta.

At least 127 records · Page 7Linked to original sources
PubMed2000

A variable resolution x-ray detector for computed tomography: I. Theoretical basis and experimental verification.

A computed tomography imaging technique called variable resolution x-ray (VRX) detection provides detector resolution ranging from that of clinical body scanning to that of microscopy (1 cy/mm to 100 cy/mm). The VRX detection technique is based on a new principle denoted as "projective compression" that allows the detector resolution element to scale proportionally to the image field size. Two classes of VRX detector geometry are considered. Theoretical aspects related to x-ray physics and data sampling are presented. Measured resolution parameters (line-spread function and modulation-transfer function) are presented and discussed. A VRX image that resolves a pair of 50 micron tungsten hairs spaced 30 microns apart is shown.

Algorithms↗
PubMed2000

Giant-cell tumour of the tendon sheath. Is radiotherapy indicated to prevent recurrence after surgery?

Giant-cell tumour of the tendon sheath, also called pigmented villonodular synovitis, is a benign tumour with a high incidence of recurrence. We have tried to identify risk factors for recurrence. Of the 48 patients included in the study, 14 received radiotherapy after surgery. Only two (4%) had a recurrence. This compares favourably with previously reported incidences of between 25% and 45%.

Adolescent↗
PubMed2000

Myocardial infarction or high-altitude pulmonary edema?

We report the case of a 60-year-old European man with myocardial infarction at high altitude (4000 m). Myocardial infarction is an uncommonly encountered problem in high-altitude trekking in the Himalayas. The paucity of coronary artery disease at high altitude (hypoxia, exercise, and age not-withstanding) is discussed. Finally, the importance of recognizing disease entities that mimic acute mountain sickness in this environment is emphasized.

Altitude Sickness↗
PubMed2000

Comparative study of antioxidant potential of tea with and without additives.

Oxidative damage is one of the many mechanism leading to chronic diseases. Therefore interest is growing in the protection afforded by antioxidant nutrients against free radical reactions. More recently, the attention has shifted to polyphenols. Polyphenols are secondary plant metabolites occurring widely in plant food. They possess outstanding antioxidant properties, suggesting a possible protective role in man. Tea (Camellia sinensis) is a widely consumed beverage throughout the world containing polyphenols more than 35% of its dry weight. In the present work we have investigated the effect of tea without milk, tea with milk and lemon tea on the serum lipid peroxidation level (as a parameter of free radical generation). The results show that there were significant decrease in serum lipid peroxidation (Malonaldehyde) level half hour after ingestion of lemon tea and tea without milk which tends to normalize with increase in time. This decrease is much significant in case of lemon tea than tea without milk after half hour or one hour. Hence the interpretation is, tea without milk is a good source of antioxidant and addition of lemon to tea increases its antioxidant potential.

Adult↗
PubMed2000

Fungal endophthalmitis after a single intravenous administration of presumably contaminated dextrose infusion fluid.

PURPOSE: To report fungal endophthalmitis in nonimmunocompromised patients, each of whom received a single intravenous administration of presumably contaminated dextrose infusion fluid for minor ailments in rural settings. METHODS: This noncomparative case series included 12 nonimmunocompromised patients (12 eyes) with culture-positive fungal endophthalmitis. All eyes underwent initial vitreous tap with injection of intravitreal antibiotics. Eleven eyes required pars plana vitrectomy and oral fluconazole or itraconazole for 4 to 6 weeks. One patient with panophthalmitis was treated with intravenous amphotericin B. To support the hypothesis that contaminated intravenous fluid was the possible risk factor, samples from 72 sealed bottles of 5% dextrose were subjected to fungal culture. RESULTS: Patients presented 1 to 11 weeks (mean, 4.6 weeks) after the intravenous infusion. All eyes had a positive smear and cultures for fungi. Aspergillus specimen was isolated in nine eyes, Candida in two eyes, and Mucor in one eye. Final visual acuity was 20/80 or better in 8 (66.6%) eyes. Eleven of the 72 samples from dextrose bottles were culture-positive for fungi: six for Aspergillus fumigatus, three for Aspergillus niger, and two for Candida albicans. CONCLUSION: A presumed contaminated intravenous infusion administered in a rural setting was found as a new risk factor for development of endogenous fungal endophthalmitis. These patients were successfully treated with pars plana vitrectomy and oral fluconazole and itraconazole therapy.

Adult↗
PubMed2000

Thalamic epidermoid cyst. A case report.

A case of thalamic epidermoid cyst is reported. Its clinical presentation, radiological, operative findings and histological findings are discussed. Intraparenchymal epidermoids are uncommon and to our knowledge only one case of thalamic epidermoid has been reported earlier. The literature is reviewed in regard to incidence, location and etiology of Intracerebral epidermoid tumor cysts.

Adult↗
PubMed2000

Serum lactate dehydrogenase in diagnosis of megaloblastic anaemia.

The present study was carried out in 75 patients of macrocytic anaemia categorised on bone marrow examination (into megaloblastic and non-megaloblastic anaemia) to evaluate the efficacy of total serum LDH levels and LDH isoenzyme pattern in the diagnosis of megaloblastic anaemia. 25 healthy adults were taken as controls. From this study it can be concluded that total serum LDH levels more than 3000 IU/L are diagnostic of megaloblastic anaemia. Reversed LDH isoenzyme pattern (LDH1 > LDH2) by chloroform inhibition test is an adjuvant in the diagnosis where total serum LDH levels are between 451-3000 IU/L and it will also differentiate megaloblastic anaemia from haemolytic anaemia.

Adolescent↗
PubMed2000

Contact trans-scleral diode laser cyclophotocoagulation treatment for refractory glaucomas in the Indian population.

PURPOSE: This study aimed to evaluate the clinical efficacy of contact diode trans-scleral cyclophotocoagulation (TSCPC) for treatment of refractory glaucomas. METHOD: Fifty two eyes of 52 patients, (post-penetrating keratoplasty glaucoma: 16 eyes; adherent leucoma with secondary glaucoma: 8 eyes; aphakic glaucoma: 6 eyes; neovascular glaucoma: 6 eyes; narrow angle glaucoma: 6 eyes; and other secondary glaucomas: 10 eyes) were followed up from 3.5-18 months (average 12 months) after TSCPC. The treatment parameters using the contact G probe were--energy: 3-4J; area: 40 spots spread over 360 degrees; site: 1.2-1.5 mm posterior to limbus. Retreatments (22 eyes; 42%) were given whenever intraocular pressure (IOP) exceeded 22 mmHg despite maximum tolerable topical therapy. RESULTS: IOP decreased from a baseline of 44.7 (+/- 7.3) mmHg to 15 (+/- 3.7) mmHg at first week and was 15.2 +/- (8.2) mmHg at the last follow up. Successful control of IOP (< 22 mmHg) occurred in 30 (58%) eyes after a single treatment and in 48 (92%) eyes following retreatment. Complications included reduction in visual acuity from light perception (LP) only to no light perception (NLP) in two eyes and phthisis bulbi in one eye. CONCLUSION: Contact trans-scleral diode laser cyclophotocoagulation is effective in lowering IOP in eyes with intractable glaucoma with few side effects in Indian subjects.

Adolescent↗
PubMed2000

Diabetic blindness: a major challenge.

Diabetes mellitus, once believed to a disease of the West, is becoming an endemic to modernising and urbanising population in our country. In the last 20 years, dramatic improvement has taken place in the diabetic eye care due to availability of new information and laser technology. The diabetic blindness is now preventable provided both the physicians and patients are well informed about the need and the timing for eye check-up. The present review attempts to provide an update to physicians taking care of diabetics.

Diabetic Retinopathy↗
PubMed1999

Structure-function analysis of tritrypticin, an antibacterial peptide of innate immune origin.

The structural requirements for the antibacterial activity of a pseudosymmetric 13-residue peptide, tritrypticin, were analyzed by combining pattern recognition in protein structures, the structure-activity knowledge-base, and circular dichroism. The structure-activity analysis, based on various deletion analogs, led to the identification of two minimal functional peptides, which by themselves exhibit adequate antibacterial activity against Escherichia coli and Salmonella typhimurium. The common features between these two peptides are that they both share an aromatic-proline-aromatic (ArProAr) sequence motif, and their sequences are retro with respect to one another. The pattern searches in protein structure data base using the ArProAr motif led to the identification of two distinct conformational clusters, namely polyproline type II and beta-turn, which correspond to the observed solution structures of the two minimal functional analogs. The role of different residues in structure and function of tritrypticin was delineated by analyzing antibacterial activity and circular dichroism spectra of various designed analogs. Three main results arise from this study. First, the ArProAr sequence motif in proteins has definitive conformational features associated with it. Second, the two minimal bioactive domains of tritrypticin have entirely different structures while having equivalent activities. Third, tritrypticin has a beta-turn conformation in solution, but the functionally relevant conformation of this gene-encoded peptide antibiotic may be an extended polyproline type II.

Amino Acid Sequence↗
PubMed1999

The crystal structure of recombinant rat pancreatic RNase A.

The three-dimensional structure of rat pancreatic RNase A expressed in Escherichia coli was determined. The backbone conformations of certain critical loops are significantly different in this enzyme compared to its bovine counterpart. However, the core structure of rat RNase A is similar to that of the other members of the pancreatic ribonuclease family. The structural variations within a loop bordering the active site can be correlated with the subtle differences in the enzymatic activities of bovine and rat ribonucleases for different substrates. The most significant difference in the backbone conformation was observed in the loop 15-25. This loop incorporates the subtilisin cleavage site which is responsible for RNase A to RNase S conversion in the bovine enzyme. The rat enzyme does not get cleaved under identical conditions. Molecular docking of this region of the rat enzyme in the active site of subtilisin shows steric incompatibility, although the bovine pancreatic ribonuclease A appropriately fits into this active site. It is therefore inferred that the local conformation of the substrate governs the specificity of subtilisin.

Amino Acid Sequence↗
PubMed1999

Asymmetric distribution of phosphatidylethanolamine in C. albicans: possible mediation by CDR1, a multidrug transporter belonging to ATP binding cassette (ABC) superfamily.

By using two molecular probes, we demonstrate that only 4% of total phosphatidylethanolamine (PtdEtn) in the plasma membrane (PM) of a human pathogenic yeast, Candida albicans, is present in its external half. Evidence is presented to show that the availability of PtdEtn could be related to the expression of a multidrug transporter CDR1 of C. albicans, and the process is energy-dependent. A homozygous CDR1 disruptant strain of C. albicans shows almost 23% reduction in the external labelling of PtdEtn. This report shows that, similar to human MDRs, yeast multidrug transporter could also be involved in aminophospholipid translocation.

ATP-Binding Cassette Transporters↗
PubMed1999

Grapefruit juice increases the bioavailability of artemether.

OBJECTIVE: To evaluate the effect of grapefruit juice on the pharmacokinetics of artemether in plasma and saliva after a single oral dose and to detect concentration-dependent electrocardiographic changes (bradycardia and QTc prolongation). METHODS: Six healthy male subjects were given a standard breakfast followed by two tablets of 50-mg artemether administered with water; 1 week later, the tablets were administered with 350 ml double-strength fresh frozen grapefruit juice. For 8 h, 17 blood- and saliva samples were collected, and 17 electrocardiograms were recorded. Drug and metabolite concentrations were measured by means of high-performance liquid chromatography with electrochemical detection. The pharmacokinetic parameters were determined using a one-compartment model. RESULTS: Grapefruit juice significantly (P = 0.001) increased the mean peak concentration (Cmax) of artemether more then twofold from 42 (SD 17) ng/ml to 107 (28) ng/ml. The time to reach Cmax (tmax) with grapefruit juice was 2.1 (0.6) h compared with 3.6 (17) h with water (P = 0.02). The area under the concentration time curve (AUC) almost doubled with grapefruit juice from 177 ng x h/ml to 336 ng x h/ml (P = 0.003). The elimination half-life remained unchanged (1.0 h vs 1.3 h). No major changes in the kinetics of the metabolite dihydroartemisinin were detected. Low artemether levels and zero dihydroartemisinin levels were found in saliva. No influences of artemether were observed on 17 electrocardiograms during the 8 h after drug intake in particular there were no signs of bradycardia or QTc prolongation. CONCLUSION: Grapefruit juice significantly increases the oral bioavailability of artemether without an effect on the elimination half-life. It suggests a role for intestinal CYP3A4 in the presystemic metabolism of artemether.

Adult↗
PubMed1999

Radial artery in CABG: could the early results be comparable to internal mammary artery graft?

BACKGROUND: The accidental detection of patency of radial artery grafts, by Acar, which had been labeled as blocked 18 years earlier, has led to its revival as a conduit in coronary artery bypass surgery. We used radial artery as one of the grafts in 287 patients from February 1996 to June 1998. Here we present our early clinical experience and the midterm angiographic follow up of the initial 62 patients. METHODS: A no touch, atraumatic harvesting technique coupled with gentle hydrostatic and pharmacological dilatation of the radial artery graft was employed. Radial artery was used to revascularize coronary vessels with >80% proximal stenosis. Postoperatively, the patients were administered a low dose nifedipine that was continued for 6 months thereafter. The patients were followed up clinically after discharge from the hospital and angiographic evaluation of the grafted radial artery by selective injection was done at a mean interval of 16.2 +/- 5.1 months (3-24 months) postoperatively. RESULTS: There was no perioperative or late myocardial infarction or mortality. No significant complications related to the harvesting of radial artery were encountered. Angiographically, the radial artery grafts were found to be patent in 96.8% of patients (60/62). Mild distal anastomotic narrowing was seen in angiogram of one patient with good filling of the target vessel. Another patient showed diffuse spasm of radial artery graft. The patency of the pedicled left internal mammary grafts was also 98.2% (56/57). All the patients were asymptomatic. CONCLUSIONS: Radial artery seems to be an excellent alternate arterial conduit for myocardial revascularization with early and midterm patency rates equivalent to that of pedicled internal mammary artery, and it should be used more often for myocardial revascularization as an adjunct to pedicled internal mammary artery graft.

Adult↗
PubMed1999

Women's status and the health of women and men: a view from the States.

We examined the status of women in the 50 American states in relation to women's and men's levels of health. The status of women in each state was assessed by four composite indices measuring women's political participation, economic autonomy, employment and earnings, and reproductive rights. The study design was cross-sectional and ecologic. Our main outcome measures were total female and male mortality rates, female cause-specific death rates and mean days of activity limitations reported by women during the previous month. Measures of women's status were strikingly correlated with each of these health outcomes at the state level. Higher political participation by women was correlated with lower female mortality rates (r = -0.51), as well as lower activity limitations (-0.47). A smaller wage gap between women and men was associated with lower female mortality rates (-0.30) and lower activity limitations (-0.31) (all correlations, P < 0.05). Indices of women's status were also strongly correlated with male mortality rates, suggesting that women's status may reflect more general underlying structural processes associated with material deprivation and income inequality. However, the indices of women's status persisted in predicting female mortality and morbidity rates after adjusting for income inequality, poverty rates and median household income. Associations were observed for specific causes of death, including stroke, cervical cancer and homicide. We conclude that women experience higher mortality and morbidity in states where they have lower levels of political participation and economic autonomy. Living in such states has detrimental consequences for the health of men as well. Gender inequality and truncated opportunities for women may be one of the pathways by which the maldistribution of income adversely affects the health of women.

Cause of Death↗