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At least 109 records · Page 6Linked to original sources
PubMed1998

Application of HPLC to counting of colored microspheres in determination of regional blood flow.

Colored microspheres have become popular compared with radioactive microspheres because they do not use radioactivity. However, they suffer from a much greater variability in their determination. We have developed a new method for assaying the dye using high-performance liquid chromatography (HPLC) with internal standard. This technique permits accurate determination of < or = 400 spheres in rat blood, heart, kidney, liver, and brain with a relative error [coefficient of variation (CV)] < 10%. To date, only three colors (white, yellow, and red) may be used because, of the five colors tested, one (violet) served as internal standard and another (blue) exhibited marked degradation during extraction. Compared with the classical spectrophotometric technique, HPLC allows a three to five times improvement in reproducibility with a relative error significantly lower (P < 0.01) than with direct spectrophotometry. Although this new technique appears to be more time consuming than the classical method, its use seems to be preferable because of the improvement in measurement sensitivity.

Animals↗
PubMed2000

Measuring morbidity: disease counts, binary variables, and statistical power.

OBJECTIVES: This study compares the use of the binary disease variables with counts of the same conditions in models of self-rated health to better understand the advantages and disadvantages of each approach. In particular, the analysis seeks to determine if statistical power is adequate for the binary variable approach. METHODS: Morbidity measures from adults in 2 large national surveys were used in both cross-sectional and longitudinal analyses. RESULTS: Although differences across the approaches are modest, the binary variable approach offers greater explanatory power and slightly higher R2 values. Despite these advantages, statistical power is insufficient in some cases, especially for conditions that are relatively rare and/or that manifest modest differences on the outcome variable. DISCUSSION: Statistical power estimates are advisable when using the binary variable approach, especially if the list of diseases and health conditions is extensive. Although a simple count of diseases may be useful in some research applications, separate counts for serious and nonserious conditions should be more useful in many research projects while avoiding the risk of inadequate statistical power.

Adult↗
PubMed2006

[Application of distilled water in sperm counting and hypoosmotic swelling test].

OBJECTIVE: To evaluate the application of distilled water in sperm-counting and hypoosmotic swelling test. METHODS: Thirty-seven semen samples were collected and each was diluted by distilled water and sodium acid carbonate-formaldehyde solution, respectively. Then the hemacytometer was used for sperm counting. Meanwhile, the percentage of swelled sperm diluted by distilled water was compared with the result of hypoosmotic swelling test recommended by WHO. Another 26 semen samples were diluted by distilled water and hypoosmotic swelling solution respectively, and the percentages of the swelled sperm were compared. RESULTS: There was no significant difference either between the sperm concentrations obtained by distilled water and sodium acid carbonate-formaldehyde solution (P > 0.05) or between the percentages of the swelled sperm diluted by distilled water and hypoosmotic swelling solution. CONCLUSION: Distilled water can not only replace sodium acid carbonate-formaldehyde solution for sperm-counting dilution but also be used as a hypoosmotic swelling solution.

Adult↗