Home About us Contact
|
Home About us Contact | ||
|
|
||
Least-squares Regression Analysis (least-square + regression_analysis)
Selected AbstractsPrediction of fat in intact cereal food products using near-infrared reflectance spectroscopy,JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 9 2005Sandra E Kays Abstract To evaluate the feasibility of an intact product approach to the near-infrared (NIR) determination of fat content, a rapid acquisition spectrometer, with an InGaAs diode-array detector and custom built sampling device, was used to obtain reflectance spectra (1100,1700 nm) of diverse cereal food products. Fat content reference data were obtained gravimetrically by extraction with petroleum ether (AOAC Method 945.16). Using spectral and reference data, partial least-squares regression analysis was applied to calculate a NIR model (n = 89) to predict fat in intact cereal products; the model was adequate for rapid screening of samples, predicting the test samples (n = 44) with root mean square error of prediction (RMSEP) of 11.8 (range 1.4,204.8) g kg,1 and multiple coefficient of determination of 0.98. Repeated repacking and rescanning of the samples did not appreciably improve model performance. The model was expanded to include samples with a broad range of particle sizes and moisture contents without reduction in prediction accuracy for the untreated samples. The regression coefficients for the models calculated indicated that spectral features at 1165, 1215 and 1395 nm, associated with CH stretching in fats, were the most critical for model development. Published in 2005 for SCI by John Wiley & Sons, Ltd. [source] Pharmacokinetics of the calcium-channel blocker diltiazem after a single intravenous dose in horses,JOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 3 2006C. C. SCHWARZWALD The pharmacokinetics of diltiazem were determined in eight healthy horses. Diltiazem HCl, 1 mg/kg i.v., was administered over 5 min. Venous blood samples were collected at regular intervals after administration. Plasma concentrations of diltiazem and desacetyldiltiazem were determined by high-performance liquid chromatography. A second, putative metabolite was detected, but could not be identified due to the lack of an authentic standard. Data were analyzed by nonlinear least-squares regression analysis. The median (minimum,maximum) peak plasma concentration of diltiazem was 727 (539,976) ng/mL. Plasma diltiazem concentration vs. time data were best described by a two-compartment model with first-order drug elimination. The distribution half-life was 12 (6,23) min, the terminal half-life was 93 (73,161) min, the mean residence time was 125 (99,206) min, total plasma clearance was 14.4 (10.4,18.6) mL/kg/min, and the volume of distribution at steady-state was 1.84 (1.46,2.51) L/kg. The normalized ratio of the area under the curve (AUC) of desacetyldiltiazem to the AUC of diltiazem was 0.088 (0.062,0.179). The disposition of diltiazem in horses was characterized by rapid distribution and elimination and a terminal half-life shorter than reported in humans and dogs. Because of the reported low pharmacologic activity, plasma diltiazem metabolite concentrations were not considered clinically important. [source] Determination of atenolol by the micelle-stabilized room-temperature phosphorescence methodologyLUMINESCENCE: THE JOURNAL OF BIOLOGICAL AND CHEMICAL LUMINESCENCE, Issue 6 2007Marcela A. Castillo Abstract A micellar-stabilized room-temperature phosphorescence (MS,RTP) method for the determination of atenolol has been developed in micellar solutions of sodium dodecylsulphate (SDS) in the presence of thallium(I) as a heavy atom and sodium sulphite as an oxygen scavenger. The effects of thallium(I) nitrate, SDS and sodium sulphite concentrations on atenolol MS,RTP intensity were studied. Optimized conditions to obtain maximum sensitivity were 0.015 mol/L thallium(I) nitrate, 0.1 mol/L SDS and 0.0075 mol/L sodium sulphite. The maximum phosphorescence signal was completely developed in 10 min and the intensity was measured at ,ex = 272 nm and ,em = 412 nm. The linear range of application obtained was 2.01,16.00 µg/mL. The detection limit estimated from the least-squares regression analysis was 0.86 µg/mL and the relative standard deviation of 10 replicates was 1.7%. The proposed method was applied to the determination of atenolol in a pharmaceutical formulation. The quantitation was carried out by means of standard calibration, standard-additions calibration and Youden calibration. These three experiments were necessary to evaluate the presence of constant and proportional errors due to the matrix. Copyright © 2007 John Wiley & Sons, Ltd. [source] L-asparaginase as a marker of chemotherapy dose modification in children with acute lymphoblastic leukemiaCANCER, Issue 12 2005Jacques Baillargeon Ph.D. Abstract BACKGROUND The objective of the current study was to compare chemotherapy dose modifications in obese (a body mass index [BMI] > 95%) and nonobese (a BMI , 95%) pediatric patients with acute lymphoblastic leukemia (ALL). METHODS The study cohort was comprised of 199 pediatric patients diagnosed with ALL who were treated at 1 of 2 South Texas pediatric oncology centers between 1990,2000. The relative chemotherapy dose modification during the induction phase of chemotherapy was calculated as the ratio of 1) the actual administered dose of L-asparaginase and 2) the protocol-calculated dose of L-asparaginase. The extent to which the chemotherapy dose modification varied according to obesity status was assessed using stratified Student t tests and an ordinary least-squares regression analysis. RESULTS Obese ALL patients were found to exhibit a 7% decrease in the mean relative modification of L-asparaginase during induction chemotherapy compared with their nonobese counterparts. This finding was statistically significant (P = 0.009), even after adjustment for gender, age, ethnicity, and clinical institution. CONCLUSIONS To the authors' knowledge, the current study is the first published report of an obesity-associated chemotherapy dose modification in pediatric patients with ALL, the most common childhood malignancy. It will be important to examine whether these findings are consistent with those observed in future studies, and ultimately to assess the association between obesity-related dose modifications and long-term cancer outcomes. Cancer 2005. © 2005 American Cancer Society. [source] | |||||||||||||