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Biomedical subjects

R A Patel

Publications and source records attributed to R A Patel.

13 recordsLinked to original sources
PubMed1996

Preliminary experience with use of a selective 5HT3 receptor antagonist (ondansetron) to prevent high dose chemotherapy induced emesis.

Ondansetron was used as an antiemetic along with dexamethasone during 16 cycles of highly or moderately ematogenic chemotherapy. There was major control in two cycles and complete control in the remaining 14. Side effects were minor and did not require discontinuation of the drug. This combination, therefore, appears to be safe and effective in preventing chemotherapy induced emesis.

Adult↗
PubMed1993

Epstein-Barr virus infectivity of Raji and Molt 4 cells: differences in cellular membrane lipids and apparent microviscosity.

Infection of lymphocytes by the Epstein-Barr virus (EBV) is initiated by attachment of the major virus glycoprotein gp350/220 to a cell surface glycoprotein, known as CR2 (CD21). In a productive infection the virus envelope fuses with host cell membranes either at the cell surface or within endocytic vesicles. To investigate the relevance of host cell membrane properties in the fusion process, we used the lymphoblastoid cell lines Raji and Molt 4. Both cell lines express CR2 and bind EBV; however, only the Raji cell supports virus-cell fusion. Lipid analysis of the two cell lines indicated that Raji cells had a significantly lower cholesterol to phospholipid molar ratio due to a greater membrane content of phospholipid relative to protein. Determination of cell membrane fluid dynamics by fluorescence polarization indicated that the apparent membrane microviscosity of Molt 4 cells was significantly greater than that of Raji. Increasing Raji cell membrane apparent microviscosity to values similar to those of Molt 4 cells by incubation with cholesteryl-hemisuccinate caused a reduction in EBV fusion with Raji cells. However, experiments designed to allow EBV infection of Molt 4 cells whose plasma membranes had been fluidized were unsuccessful. These studies suggest that the lipid composition and other as yet unidentified factors are involved in entry of EBV into cells.

Cell Line↗
PubMed1993

Insulin stimulates phosphatidylinositol 3-kinase activity in rat neuronal primary cultures.

We investigated the effect of insulin on phosphatidylinositol (PtdIns) 3-kinase (PtdIns 3-kinase) activity in neuronal cultures to determine if this enzyme is involved with the neurotrophic actions of insulin. Insulin caused a concentration-dependent increase in PtdIns 3-kinase activity in anti-phosphotyrosine immunoprecipitates. The kinase activity was able to phosphorylate PtdIns, PtdIns 4-phosphate, and PtdIns 4,5-bisphosphate. In intact neurons, a 10-min 1 mM insulin treatment in the presence of [32P]orthophosphate increased the levels of both 3-[32P]PtdIns phosphate and 3,4-[32P]PtdIns bisphosphate by 55 and 193%, respectively. This increase was associated with an increase in neurite outgrowth mediated by insulin. Our results indicate that insulin treatment of neuronal cells in primary culture increases PtdIns 3-kinase activity and the formation of the unique D-3-phosphorylated phosphoinositides, suggesting that growth factor-mediated neuronal growth may include the formation of novel phosphoinositide 3-phosphate phospholipids.

Animals↗
PubMed1989

Bayesian forecasting of serum lithium concentrations. Comparison with traditional methods.

Twelve pharmacokinetic methods of estimating lithium maintenance dosage requirements were compared in 21 patients with bipolar illness. Methods which were compared included the single- and multiple-point methods of Perry, 4 non-linear regression and 6 Bayesian methods. The REVOL algorithm was employed for converging on to estimates of clearance and apparent volume of distribution for the non-linear regression and Bayesian methods. Data analysis was based on an evaluation of prediction error as a measure of bias, and absolute prediction error as a measure of precision. In a direct comparison, there were no statistically significant differences in bias or precision between any of the methods.

Adolescent↗
PubMed1988

Transdermal delivery of isoproterenol HCl: an investigation of stability, solubility, partition coefficient, and vehicle effects.

Effects of solubility, partition coefficient, and selected adjuvants (propylene glycol and Azone) on percutaneous penetration of isoproterenol HCl have been investigated using human cadaver skin. Isoproterenol was found to be stable (less than 1% decomposition) for 24 hr at 22 +/- 0.5 degrees C in the pH range 1 to 7 in the following solvents: water, normal saline, propylene glycol and a series of propylene glycol-water mixtures (10, 20, 40, and 60%; v/v); however, decomposition was significant beyond pH 8. In normal saline, the rate of decomposition increased significantly with an increase in temperature to 37 degrees C. The solubility of isoproterenol HCl decreased and its skin/vehicle partition coefficient increased with increasing proportions of propylene glycol in the vehicle, while the product of the solubility and partition coefficient appeared to plateau at 20% propylene glycol in water. Optimal penetration enhancing effects of Azone were seen when incorporated at a concentration of 1% (v/v) in the 20% (v/v) propylene glycol-water blend and, more significantly, when skin was pretreated with pure Azone for 60 min prior to application of the drug formulation.

Azepines↗
PubMed1988

Comparison of pharmacokinetic procedures for dosing lithium based on analysis of prediction error.

Five pharmacokinetic methods for estimating maintenance dosage requirements of lithium carbonate were compared retrospectively in 20 inpatients with acute bipolar illness. Specific pharmacokinetic methods tested included the method of Cooper, the multiple-point method of Perry, the single-point method of Perry, the method of Zetin, and the method of Pepin. Data analysis was based on evaluation of prediction error or the difference between the predicted steady-state lithium concentration and the measured steady-state lithium concentration at equivalent daily doses. Each dosing method was assessed in regard to accuracy and bias of predicted steady-state serum lithium concentrations. Bias was assessed by comparison of the median value of the prediction error with zero. The dosing recommendation based on the Cooper nomogram resulted in a significant positive bias (p less than or equal to 0.05). Intermethod accuracy was assessed by comparison of the absolute prediction errors of each dosing method. Significant differences in accuracy were observed between the method of Pepin when compared with the single-point method of Perry (p less than or equal to 0.05, k-sample sign test). All other comparisons were nonsignificant.

Adolescent↗
PubMedDate not supplied

Helical CT for the evaluation of suspected acute pulmonary embolism: diagnostic pitfalls.

Helical CT is being increasingly utilized for the evaluation of suspected pulmonary embolism (PE). Proper scan interpretation depends on the awareness of several diagnostic pitfalls that may simulate PE, including normal bronchovascular structures such as pulmonary veins, bronchi, and lymph nodes, technical considerations such as improper bolus timing and streak artifacts, and patient-related factors such as motion artifacts, pulmonary arterial catheters, and vascular shunts. An understanding of these pitfalls facilitates accurate diagnosis.

Acute Disease↗
PubMedDate not supplied

Hypersensitivity pneumonitis: patterns on high-resolution CT.

Hypersensitivity pneumonitis, also known as extrinsic allergic alveolitis, is caused by inhalation of specific environmental organic antigens. This disease may have typical high-resolution CT findings that, in the appropriate clinical setting, can be sufficiently characteristic to allow a confident diagnosis without the need for a lung biopsy. In this pictorial essay, the high-resolution CT patterns of hypersensitivity pneumonitis are illustrated. The authors emphasize the correlation among the radiologic presentation, functional abnormalities, and pathologic findings.

Adult↗