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Reference Methods (reference + methods)
Selected AbstractsEvaluation of a single-platform microcapillary flow cytometer for enumeration of absolute CD4+ T-lymphocyte counts in HIV-1 infected Thai patients,,CYTOMETRY, Issue 5 2007Kovit Pattanapanyasat Abstract Background: Various assays are used to enumerate peripheral blood absolute CD4+ T-lymphocytes. Flow cytometry is considered the gold standard for this purpose. However, the high cost of available flow cytometers and monoclonal antibody reagents make it difficult to implement such methods in the resource-poor settings. In this study, we evaluated a cheaper, recently developed single-platform microcapillary cytometer for CD4+ T-lymphocyte enumeration, the personal cell analyzer (PCA), from Guava® Technologies. Methods: CD4+ and CD8+ T-lymphocyte counts in whole blood samples from 250 HIV-1 infected Thais were determined, using a two-color reagent kit and the Guava PCA, and compared with the results obtained with two reference microbead-based methods from Becton Dickinson Biosciences: the three-color TruCOUNTÔ tube method and the two-color FACSCountÔ method. Statistical correlations and agreements were determined using linear correlation and Bland,Altman analysis. Results: Absolute CD4+ T-lymphocyte counts obtained using the Guava PCA method highly correlated with those obtained using TruCOUNT method (R2 = 0.95, mean bias +13.1 cells/,l, limit of agreement [LOA] ,101.8 to +168.3 cells/,l). Absolute CD8+ T-lymphocyte counts obtained using the Guava PCA method also highly correlated with those obtained with the two reference methods (R2 = 0.92 and 0.88, respectively). Conclusion: This study shows that the enumeration of CD4+ T-lymphocytes using the Guava microcapillary cytometer PCA method performed well when compared with the two reference bead-based methods. However, like the two reference methods, this new method needs substantial technical expertise. © 2007 Clinical Cytometry Society. [source] A new maximum entropy-based method for deconvolution of spectra with heteroscedastic noiseJOURNAL OF CHEMOMETRICS, Issue 12 2004Bård Buttingsrud Abstract Broadening of spectral lines combined with large and heteroscedastic noise contributions constitutes an important problem in analytical chemistry. Reduced interpretability and artefacts in further data analysis make deconvolution methods necessary. A new robust deconvolution method (RHEMEM) based on the principle of maximum entropy is proposed in order to effectively handle the presence of heteroscedastic noise. Other deconvolution methods such as Jansson's method, Fourier self-deconvolution and LOMEP are also studied with respect to their ability to handle heteroscedastic noise. A systematic simulation study is used to compare the performance of the new method with the reference methods. They are evaluated according to reconstruction performance, robustness and the ability to work without manual input. Copyright © 2005 John Wiley & Sons, Ltd. [source] Qualitative in situ analysis of multiple solid-state forms using spectroscopy and partial least squares discriminant modelingJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 7 2007Karin Kogermann Abstract This study used in situ spectroscopy to reveal the multiple solid-state forms that appear during isothermal dehydration. Hydrate forms of piroxicam and carbamazepine (CBZ) were investigated on hot-stage at different temperatures using near-infrared (NIR) and Raman spectroscopy combined with multivariate modeling. Variable temperature X-ray powder diffraction, differential scanning calorimetry, thermogravimetric analysis, and Karl Fisher titrimetry were used as reference methods. Partial least squares discriminant analysis (PLS-DA) was performed to qualitatively evaluate the phase transition. It was shown that the constructed PLS-DA models, where spectral differences were directly correlated to solid-state modifications, enabled differentiation between the multiple forms. Qualitative analysis revealed that during dehydration, hydrates, such as CBZ dihydrate, may go through several solid-state forms, which must be considered in quantitative model construction. This study demonstrates that in situ analysis can be used to monitor the dehydration and reveal associated solid-state forms prior to quantification. The utility of the complementary spectroscopic techniques, NIR and Raman, have been shown. © 2007 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 96: 1802,1820, 2007 [source] Analysis of canine and feline haemograms using the VetScan HMT analyserJOURNAL OF SMALL ANIMAL PRACTICE, Issue 10 2003E. C. Dewhurst The VetScan HMT is an impedance counter haematology analyser which produces a full blood count and three-part white blood cell differential. The aim of this study was to compare the results generated by the analyser with those obtained by standard methods used routinely in the authors'laboratory. Blood samples from 68 dogs and 59 cats were run on the VetScan HMT analyser and also subjected to reference methods, and the results obtained were compared. Correlation coefficients (feline/canine) were: 0·97/0·99 for haematocrit (Hct), 0*middot;98/0·99 for haemoglobin (Hb), 0·81/0·98 for total white blood cells (WBC), and 0·89/0·97 for granulocyte and 0·65/0·93 for platelet counts. Coefficients for lymphocyte counts were 0·25/0·28 and for monocyte counts were 0·12/0·79. In conclusion, the VetScan HMT performed well on canine samples, showing excellent correlation for canine Hct, Hb, RBC, WBC, granulocyte and platelet counts. For feline samples, although there was excellent correlation for Hct, Hb and RBC, the WBC and three-part white blood cell differential and platelet count should be interpreted with caution as they can be unreliable. [source] Evaluation of lignans and free and linked hydroxy-tyrosol and tyrosol in extra virgin olive oil after hydrolysis processesJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 5 2006Nadia Mulinacci Abstract We describe chemical hydrolytic procedures to evaluate the total amount of tyrosol and hydroxy-tyrosol free and/or linked to secoiridoidic molecules (acid hydrolysis). At the same time a rapid determination of the lignans in complex minor polar compound (MPC) extracts is proposed (alkaline hydrolysis). High-performance liquid chromatography/diode array detection (HPLC/DAD) and HPLC/MS were applied as reference methods to evaluate the quantitative results from the hydrolysis experiments. The optimized acid hydrolysis procedures were first applied to an oleuropein standard and then to MPC fractions extracted from several commercial extra virgin olive oils. The results confirm the applicability of the method, consisting in the acid hydrolysis of complex mixtures of secoiridoidic derivatives, to determine the antioxidant potential in terms of MPC. These data can contribute to forecasting the potential ageing resistance of an extra virgin olive oil in terms of antioxidant potency. Finally, alkaline hydrolysis allows confirmation and easy determination of the amount of lignans, especially in those MPC fractions which are particularly complex. Copyright © 2006 Society of Chemical Industry [source] | ||||||||||