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At least 199 records · Page 11Linked to original sources
PubMed1994

Sources of error associated with sample collection and preparation of nucleated blood cells for flow cytometric analysis.

Analysis of cellular DNA content by flow cytometry has been used to detect genetic changes associated with exposure to environmental contaminants. In lower vertebrates, nucleated red blood cells can be collected for analysis without harm to the animal. Because erythrocytes sampled from an individual should have identical amounts of DNA, the coefficient of variation (CV) around the G0/G1 peak should be small. Increases in CV can indicate genetic aberrations, but may also be caused by sample handling and preparation or problems with instrumentation. To increase confidence in associating increases in CV with external causes, artifactual changes in CV due to sample treatment and instrument parameters should be identified and minimized. We assessed the effects of various sampling and handling protocols on the CV of nucleated blood cells collected from largemouth bass (Micropterus salmoides). We also compared the distribution of cells among the G0/G1, S, and G2/M phases of the cell cycle to see whether these were affected by sampling or treatment protocols. Groups of 7 fish were bled on 7 consecutive days, and blood from each fish was analyzed by flow cytometry when freshly collected, and after freezing for 1 hour or 10 days. The same fish were bled again over a consecutive 7-day period, and the experiment was repeated. CV and cell cycle distribution were not affected by our freezing protocol. Repeat sampling from the same individual did not affect CV, but altered the distribution of cells in the cell cycle, suggesting increased hemopoiesis in response to blood sampling.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1980

Changing measurement instrument at follow-up: a potential source of error.

The purpose of this investigation was to determine whether headache activity information collected over the phone can be directly compared with headache activity information collected by systematic self-observation without jeopardizing internal validity because of calibration differences between the two measurement methods. A number of headache studies have relied on phone information for long-term follow-up data, while using systematic self-observation to collect all other data. Twenty-six headache sufferers participating in a tension headache study reported their headache activity over the phone and subsequently charted their headaches. Correlations were computed between the two measures. Results indicated that differences exist in the calibration of the two measurement methods. This seriously limits the conclusions of studies that used phone information to obtain follow-up data. Other recommendations concerning follow-up methodologies are discussed.

Adult↗
PubMed1985

Storage of irradiated human blood; a source of error in quantitative chromosome analysis.

Human whole blood was irradiated with 2.5 Gy of 220 k Vp X-rays and stored before culture with 9.7 microM BrdU and 19.4 or 38.7 microM BrdU for 0, 24, 48 and 72 h. The frequency of dicentrics and ring chromosomes was determined in cells staining as first division (M1) metaphases with the fluorescence plus Giemsa technique. Storage had no influence on the observed aberration yields in 44 h cultures containing 9.7 microM BrdU. In 66 h cultures at 19.4 microM BrdU the observed yields after 2 and 3 days' storage were significantly lower as compared to cultures from fresh blood. No storage effect was revealed in 66 h cultures containing 38.7 microM BrdU. In cases where cytogenetic radiation dosimetry has to be carried out using blood samples which have been in transit for 2-3 days, the findings are of relevance for a correct determination of the chromosome damage in M1 cells.

Blood Preservation↗