The Experts below are selected from a list of 225 Experts worldwide ranked by ideXlab platform
J Arteche - One of the best experts on this subject based on the ideXlab platform.
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Population Dose in the vicinity of old spanish uranium mines
Science of The Total Environment, 2004Co-Authors: L Quindos S Poncela, P Fernandez L Navarro, Gomez J Arozamena, Rodenas C Palomino, Carlos Sainz, J Martin L Matarranz, J ArtecheAbstract:Regional surveys were conducted to determine exposure to natural sources of radiation for people in the vicinity of old Spanish uranium mines. The surveys evaluated indoor radon concentrations and outdoor and indoor external gamma Dose rates. Indoor radon concentrations were measured in 222 dwellings by means of nuclear track-etched detectors. The terrestrial gamma ray Dose rate was measured outdoors and indoors at a total of 256 points and 115 points, respectively. Estimates mean annual effective Doses for the six areas studied ranged from 3.2 to 5.1 mSv per year, which is between 1.2 and 2 times higher than the average national value.
Kenneth G Kowalski - One of the best experts on this subject based on the ideXlab platform.
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Population Dose response analysis of daily seizure count following vigabatrin therapy in adult and pediatric patients with refractory complex partial seizures
The Journal of Clinical Pharmacology, 2015Co-Authors: Jace Nielsen, Matthew M Hutmacher, David L Wesche, Dwain Tolbert, Mahlaqa Patel, Kenneth G KowalskiAbstract:Vigabatrin is an irreversible inhibitor of γ-aminobutyric acid transaminase (GABA-T) and is used as an adjunctive therapy for adult patients with refractory complex partial seizures (rCPS). The purpose of this investigation was to describe the relationship between vigabatrin dosage and daily seizure rate for adults and children with rCPS and identify relevant covariates that might impact seizure frequency. This Population Dose–response analysis used seizure-count data from three pediatric and two adult randomized controlled studies of rCPS patients. A negative binomial distribution model adequately described daily seizure data. Mean seizure rate decreased with time after first Dose and was described using an asymptotic model. Vigabatrin drug effects were best characterized by a quadratic model using normalized dosage as the exposure metric. Normalized dosage was an estimated parameter that allowed for individualized changes in vigabatrin exposure based on body weight. Baseline seizure rate increased with decreasing age, but age had no impact on vigabatrin drug effects after dosage was normalized for body weight differences. Posterior predictive checks indicated the final model was capable of simulating data consistent with observed daily seizure counts. Total normalized vigabatrin dosages of 1, 3, and 6 g/day were predicted to reduce seizure rates 23.2%, 45.6%, and 48.5%, respectively.
B.f. Wall - One of the best experts on this subject based on the ideXlab platform.
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UK Population Dose from medical X-ray examinations.
European journal of radiology, 2004Co-Authors: D. Hart, B.f. WallAbstract:Objective: To assess the annual per caput and collective effective Dose to the United Kingdom Population from medical and dental X-ray examinations. Method: The results of a detailed survey of the frequency of X-ray examinations during the financial year 1997/1998 were combined with contemporary data on the effective Doses typically received by patients. The resulting per caput and collective Dose for 1997/1998 was updated to 2001/2002 by using annual statistics on the total numbers of computed tomography (CT), interventional and conventional examinations collected by the English Department of Health. Results: The annual per caput effective Dose for the UK in 2001/2002 was estimated at 0.38 mSv. Over the last 10 years CT has more than doubled its contribution and is now responsible for 47% of the collective Dose from medical X-rays. The contribution from conventional radiographic and fluoroscopic examinations has nearly halved to about 34%. Interventional and angiographic procedures together contribute the remaining 19%. Conclusions: The annual per caput effective Dose of 0.38 mSv is low in comparison with other countries having similarly developed systems of health-care. This is due to both a lower frequency of X-ray examinations per head of Population and generally lower Doses in the UK than in other developed countries.
Nancy C. Sambol - One of the best experts on this subject based on the ideXlab platform.
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Felodipine Population Dose‐response and concentration‐response relationships in patients with essential hypertension
Clinical pharmacology and therapeutics, 1995Co-Authors: Janet R. Wade, Nancy C. SambolAbstract:Objectives To characterize the Population Dose-response and concentration-response relationships of felodipine and to investigate the influence of patient variables on these relationships. Methods We studied 239 evaluable patients with mild to moderate essential hypertension in a multicenter, randomized, double-blind Dose-escalation trial, followed by an optional open-label maintenance phase for the remainder of 1 year. Extended-release felodipine (2.5 to 20 mg) monotherapy was given once daily. Felodipine plasma concentration and sitting diastolic blood pressure were measured at approximately 2 and 24 hours after drug administration. Analysis, performed with use of the Population approach (NONMEM program), accounted for baseline and placebo effects. Results A saturation (Emax) model best described both felodipine Dose response (only 24-hour postDose data) and concentration response. The maximum effect (Emax) characterizing Dose response was found to increase linearly with age and was estimated to be 20.6 mm Hg in the typical individual (60 years of age). The Dose at which 50% of the maximum effect is achieved (D50) was estimated to be 11.1 mg. The Emax characterizing concentration response also increased linearly with age and was estimated to be 27.8 mm Hg for the typical individual. The concentration at which 50% of the maximum effect is achieved (C50) was related to plasma renin activity (PRA) by the following: (21.6 · PRA)/(0.25 + PRA) nmol/L; its value in the typical individual was estimated to be about 16.9 nmol/L. Felodipine (oral) clearance decreased with increasing age, up to 60 years, and was larger in black patients. Conclusions The effects of age on felodipine pharmacokinetics and pharmacodynamics lead to a heightened antihypertensive response in the elderly. A starting Dose of 2.5 mg daily is recommended, especially in elderly patients. Clinical Pharmacology & Therapeutics (1995) 57, 569–581; doi:
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Population Dose versus response of betaxolol and atenolol a comparison of potency and variability
Clinical Pharmacology & Therapeutics, 1991Co-Authors: Nancy C. Sambol, Lewis B SheinerAbstract:The Dose-response curves of betaxolol and atenolol were compared in 140 patients with mild to moderate essential hypertension. Patients with a supine diastolic blood pressure of 95 to 115 mm Hg at the end of a 4-week single-blind placebo washout phase were randomized (double-blind) to receive either betaxolol or atenolol in a Dose-escalation manner. The Dose (5 mg, 10 mg, and 20 mg betaxolol; 25 mg, 50 mg, and 100 mg atenolol) was increased if the supine diastolic blood pressure remained greater than 90 mm Hg after 4 weeks at each level. The final Dose in the escalation phase was continued for an additional 12 weeks and then followed by a 2-week placebo phase. The data were analyzed with a Population model using the program NONMEM (nonlinear mixed effects model). Atenolol exhibited a graded Dose-response curve, whereas the lowest Dose of betaxolol produced maximum or near-maximum effect. The estimated maximum effect (drug plus possibly unmeasured placebo effect) was similar for both treatments, about 13 mm Hg (95% confidence interval, 10 to 15 mm Hg). A trend toward less interindividual variability (coefficient of variation) was apparent for betaxolol compared to atenolol, 19% (95% confidence interval, 0% to 29%) versus 31% (95% confidence interval, 0% to 47%). The intraindividual variability (standard deviation) in supine diastolic blood pressure, 5.9 mm Hg (95% confidence interval, 5.2 to 6.5 mm Hg), did not differ significantly between drugs despite significantly greater intraindividual variability (coefficient of variation) in atenolol concentrations, 62% (95% confidence interval, 48% to 73%) versus 26% (95% confidence interval, 22% to 29%) for betaxolol.
L Quindos S Poncela - One of the best experts on this subject based on the ideXlab platform.
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Population Dose in the vicinity of old spanish uranium mines
Science of The Total Environment, 2004Co-Authors: L Quindos S Poncela, P Fernandez L Navarro, Gomez J Arozamena, Rodenas C Palomino, Carlos Sainz, J Martin L Matarranz, J ArtecheAbstract:Regional surveys were conducted to determine exposure to natural sources of radiation for people in the vicinity of old Spanish uranium mines. The surveys evaluated indoor radon concentrations and outdoor and indoor external gamma Dose rates. Indoor radon concentrations were measured in 222 dwellings by means of nuclear track-etched detectors. The terrestrial gamma ray Dose rate was measured outdoors and indoors at a total of 256 points and 115 points, respectively. Estimates mean annual effective Doses for the six areas studied ranged from 3.2 to 5.1 mSv per year, which is between 1.2 and 2 times higher than the average national value.