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At least 1,153 records · Page 64Linked to original sources
PubMed2006

Short communication: effectiveness of sample duplication to control error in ruminant digestion studies.

Eight ruminally cannulated lactating dairy cows from a study on the effect of dietary rumen-degraded protein on production and digestion of nutrients were used to assess using sample duplication to control day-to-day variation within animals and errors associated with sampling and laboratory analyses. Two consecutive pooled omasal samples, each representing a feeding cycle, were obtained from each cow in each period. The effectiveness of sample duplication in error control was tested by comparing the variance of the difference in treatment means when taking 2 samples from each cow in each period to the variance when taking only one sample. Compared with no duplication, sample duplication improved precision by reducing variance by 50, 40, 31, 23, 23, and 9% for, respectively, rumen-undegraded protein flows, ruminal neutral detergent fiber digestibility, microbial nonammonia N flow, microbial efficiency, organic matter flow, and organic matter truly digested in the rumen. For these same variables, reductions in the standard errors of the difference between treatment means due to sample duplication represented 100, 87, 73, 59, 58, and 27% of the predicted reductions resulting from doubling the number of experimental units without sample duplication. Sample duplication can substantially reduce experimental error originating from day-to-day variation within cows, sample collection, and laboratory analyses, thus improving statistical power in ruminant digestion studies.

Animals↗
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↗
PubMed1979

Gross errors made by routine blood sampling from two sites using a tourniquet applied at different positions.

Tourniquet application in routine blood sampling procedures may induce considerable haemoconcentration and thereby augment the concentration of serum protein and protein-bound substances. To evaluate this effect serum protein, calcium and magnesium were measured in 31 healthy persons before and after 3-min venous stasis induced by a standardized tourniquet. Four sites of tourniquet and two sampling sites on the arm were compared. The concentration of measured serum constituents rose after the stasis period (5--13% rise in serum protein), the changes being similar at all tourniquet positions. However, blood sampled from a cubital arm vein showed significantly larger haemoconcentration than samples obtained simultaneously more distally on the arm. Taking three samples in a series, the serum concentration of protein, calcium and magnesium rose from tube to tube (5--10% change). The study demonstrates that neither use of a standardized tourniquet nor release of the tourniquet before blood sampling eliminates the errors inherent in routine venepuncture. Adjustment to a constant serum protein level minimizes these errors.

Adolescent↗
PubMed2006

An intercalibration study on organobromine compounds: Results on polybrominated diphenylethers and related dioxin-like compounds.

An intercalibration study on organobromine compounds has been conducted to evaluate the accuracy and reliability in the analysis of brominated flame retardants (BFRs) such as polybrominated diphenyl ethers (PBDEs) and their related compounds like polybrominated and monobromo-polychlorinated dibenzodioxins and -furans (PBDDs/DFs, MoBPCDDs/DFs). This paper reports the results for these compounds in 'Mixed Standard Solutions' and 'Air-Dried Sediment'. The relative standard deviations (RSDs) for PBDEs, PBDDs/DFs and MoBPCDDs/DFs in mixed standard solutions ranged from 9% to 24%, 4% to 20% and 8% to 27%, respectively. The results of this study are better than those reported in earlier international interlaboratory studies due to general improvement in analytical methods and an increasing number of available authentic standards, particularly for PBDEs. In the analysis for higher brominated compounds such as octabromodibenzodioxin, the participants were advised to optimize the calibration curves befitting the range of concentrations found in samples because variation of relative response factors was noted. The results for 'Air-Dried Sediment' were also reasonable with RSDs from 10% to 38% for PBDEs, 8% to 38% for PBDDs/DFs and 17% to 36% for MoBPCDDs/DFs. In the sediment sample, possible errors in the sample pretreatment and/or interference by other compounds/impurities were indicated. The concentrations of pentabromodiphenylether, BDE100, varied more than the other PBDE isomers due to its poor separation in some chromatographic conditions. In addition, interference by PBDEs was observed in the analysis for PBDFs. Potential degradation/secondary formulation of PBDEs and PBDFs during the Soxhlet extraction were suggested when copper powder was added into the sediment samples. Inspite of these observations, the results in this study are better than those reported in other interlaboratory studies due to the advice given to participants for improving the results. Compared with the results for PCDDs/DFs (5-23% RSDs) and Co-PCBs (6-24% RSDs), the RSDs for most of the organobromine compounds were high, indicating an immature QA/QC approach for the analysis of PBDEs and related compounds in comparison to common chlorinated dioxins.

Calibration↗
PubMed2003

Glyphosate tolerant canola meal is equivalent to the parental line in diets fed to rainbow trout.

Two separate studies were conducted to evaluate the utility of glyphosate tolerant canola (GTC) as a feed ingredient in diets fed to rainbow trout. In the first study, two forms of GTC were compared to a parental line, Westar. In the second study, one line of GTC was reevaluated to Westar. In each study, processed canola meals were incorporated at 5, 10, 15, or 20% of the dry diet and a diet containing no canola was fed for comparison. All diets were fed to triplicate groups of fish in each study. In the first study, weight gain, feed efficiency (FE), protein efficiency ratio (PER), and protein retention (PR) were not significantly different in fish fed either Westar or GT200 at any level of substitution. Fish fed GT73 exhibited a gradual reduction in weight gain, FE, and PER as the level of GTC increased. However, the only significant reduction was in weight gain of fish fed 20% GT73 as compared to fish fed 5% GT73. Because of an error in preparing samples prior to the experiment, samples GT200 and GT73 were essentially equivalent in composition. The differences were explained by differences in processing temperatures that occurred after the sample mixing error occurred. In the second study, mean weight gain, PR, and survival were not significantly different among forms of canola. FE and PER values were significantly lower in fish fed 15% Westar as compared to fish fed 10% Westar; other FE and PER values were not significantly different. On the basis of these results, GTC processed into a toasted meal and incorporated into diets for rainbow trout is equivalent to a parental line of canola.

Animal Feed↗
PubMed1994

Evaluation of counting error due to colony masking in bioaerosol sampling.

Colony counting error due to indistinguishable colony overlap (i.e., masking) was evaluated theoretically and experimentally. A theoretical model to predict colony masking was used to determine colony counting efficiency by Monte Carlo computer simulation of microorganism collection and development into CFU. The computer simulation was verified experimentally by collecting aerosolized Bacillus subtilis spores and examining micro- and macroscopic colonies. Colony counting efficiency decreased (i) with increasing density of collected culturable microorganisms, (ii) with increasing colony size, and (iii) with decreasing ability of an observation system to distinguish adjacent colonies as separate units. Counting efficiency for 2-mm colonies, at optimal resolution, decreased from 98 to 85% when colony density increased from 1 to 10 microorganisms cm-2, in contrast to an efficiency decrease from 90 to 45% for 5-mm colonies. No statistically significant difference (alpha = 0.05) between experimental and theoretical results was found when colony shape was used to estimate the number of individual colonies in a CFU. Experimental colony counts were 1.2 times simulation estimates when colony shape was not considered, because of nonuniformity of actual colony size and the better discrimination ability of the human eye relative to the model. Colony surface densities associated with high counting accuracy were compared with recommended upper plate count limits and found to depend on colony size and an observation system's ability to identify overlapped colonies. Correction factors were developed to estimate the actual number of collected microorganisms from observed colony counts.(ABSTRACT TRUNCATED AT 250 WORDS)

Aerosols↗
PubMedDate not supplied

Meta-analysis of 2-treatment clinical trials including both continuous and dichotomous results.

To expedite the timely creation of medical practice guidelines, a meta-analytic method was developed to combine both dichotomous survival data and continuous physiologic data from multiple studies of differing experimental design, which compare the same innovative clinical intervention to standard care. An aggregate ratio, R*, of the observed treatment effect to a clinically optimal treatment effect for studies in a series is computed and compared to the 95% confidence limit for R* under the null hypothesis. Input data for continuous variables include sample means, standard errors, and sample sizes. Input data for dichotomous variables include group proportions and sizes. The analysis can be done using a simple, 1-page spreadsheet. It allows one to judge biological significance, to test for statistical significance, to compare subgroups of studies, to test for outliers, and to compute the power of the meta-analysis. These features are demonstrated for studies of interposed abdominal compression-cardiopulmonary resuscitation.

Abdomen↗
PubMed2005

[Samples for therapeutic errors in cupping therapy].

OBJECTIVE: To explore mechanisms, operating principle, indications and contraindications of cupping therapy. METHODS: Analyze some examples of clinically erroneous application of cupping therapy. RESULTS: Erroneous application of cupping therapy for the patient of deficiency syndrome has a poor therapeutic effect, even exacerbates. CONCLUSION: Clinically, application ranges of cupping therapy should be definited.

Acupuncture Points↗
PubMed1986

A comparison of confidence interval methods for the intraclass correlation coefficient.

Different methods of obtaining confidence intervals for the intraclass correlation coefficient rho in the unbalanced one-way random-effects model are investigated, focusing on applications to family studies. Methods based on simple modifications of formulas for the case of equal group sizes are found to provide adequate coverage at small to moderate values of rho. A method based on the large-sample standard error of the sample intraclass correlation, as derived by Smith (1956, Annals of Human Genetics 21, 363-373), is shown to provide consistently good coverage at all values of rho. A method proposed by Thomas and Hultquist (1978, Annals of Statistics 6, 582-587) also provides consistently good coverage, but generates mean interval widths substantially greater than those generated by Smith's method at values of rho likely to arise in practice.

Biometry↗