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Tube Method (tube + method)

Distribution by Scientific Domains

Chemistry	60%

Selected Abstracts

Evaluation of a single-platform microcapillary flow cytometer for enumeration of absolute CD4+ T-lymphocyte counts in HIV-1 infected Thai patients,,

CYTOMETRY, Issue 5 2007
Kovit 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]

An improved method for detecting red cells with hemoglobin H inclusions that does not require glass capillary tubes

INTERNATIONAL JOURNAL OF LABORATORY HEMATOLOGY, Issue 2 2003
D.E. Sabath
Summary, -Thalassemia trait is the most common inherited abnormality worldwide. Diagnosis of , -thalassemia trait can be difficult as there are no abnormalities detectable by hemoglobin electrophoresis or high-performance liquid chromatography. Detection of individuals with , -thalassemia trait, particularly the type present in many Asian populations, is important for genetic counseling purposes, because these individuals are at risk for having offspring with hemoglobin Bart's hydrops fetalis, a fatal condition. The best routine diagnostic method to detect individuals with , -thalassemia trait is staining reticulocyte-enriched red cell preparations with brilliant cresyl blue to detect hemoglobin H inclusions. Current methods use centrifugation of microhematocrit tubes to enrich for reticulocytes, which presents a laboratory safety hazard. In this report, we describe an alternative technique to enrich for reticulocytes that does not require glass capillary tubes, but is as effective as the capillary tube method for reticulocyte enrichment and detection of cells containing hemoglobin H inclusions. [source]

THERMAL DEGRADATION KINETICS OF SUCROSE, GLUCOSE AND FRUCTOSE IN SUGARCANE MUST FOR BIOETHANOL PRODUCTION

JOURNAL OF FOOD PROCESS ENGINEERING, Issue 5 2006
J. NOLASCO JR.
ABSTRACT Thermal degradation of sugars contained in sugarcane must (21.5°Brix, pH 6.14) was evaluated at temperatures of 110, 120, 130 and 140C, using the thermal-death-time tube method, determining remaining sugars by high-pressure liquid chromatography. The study analyzed thermal degradation kinetics of both the total reducing sugars (TRS) and glucose and fructose individually. All curves of remaining sugars presented strong nonlinearity, with initial shoulder and final tail adjusted by an extended logistic model that was adapted for two species for TRS, and a simple logistic model for the monosaccharides. It was shown that rate constants are influenced by temperature according to two irreconcilable methods: the Arrhenius and the Bigelow methods. Obtained activation energies for fructose and glucose were quite coincident, 140.37 and 140.23 kJ/mol, respectively. Thermal resistance parameters were 21.59 and 21.61C, respectively. Comparison of the rate constants revealed that fructose degraded approximately 9,10 times faster than glucose. [source]

Modified volume expansion method for measuring gas holdup

THE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 2 2002
Annie X. Meng
Abstract A simple, modified volume expansion method, or inclined tube method, is compared to the pressure difference method for determining gas holdup in an airlift bioreactor. The modified volume expansion method could be used for all pneumatic bioreactors where fluid fluctuation is vigorous and visual observation of the continuous phase rise is difficult. The overall gas holdup data measured using the inclined tube method are shown to be very close to overall gas holdup determined using a gamma ray density monitor system. However, the overall gas holdup measured by the pressure difference method is found to be significantly different. This difference is due to energy dissipation in the External Loop Airlift Bioreactor (ELAB) used in this study, which causes the pressure difference method to be incorrect. On compare une méthode d'expansion de volume modifiée simple, ou méthode à tubes inclinés, à une méthode de différence de pression pour déterminer la rétention des gaz dans un bioréacteur à air ascendant. La méthode d'expansion de volume modifiée pourrait être utilisée pour tous les bioréacteurs pneumatiques oú la fluctuation du fluide est vigoureuse et l'observation visuelle de l'ascension de la phase continue difficile. Les données globales de rétention de gaz mesurées à l'aide de la méthode à tubes inclinés s'avèrent très proches de la rétention de gaz globale déterminéd à l'aide d'un moniteur de densité à rayons gamma. Toutefois, on a trouvé que la rétention de gaz globale mesurée par la méthode de différence de pression était significativement différente. Cette différence est due à la dissipation d'énergie dans le bioréacteur à air ascendant à boucle externe (ELAB) utilisé dans I'étude, qui rend la méthode de différence de pression incorrecte. [source]