Coefficent Of Variation Research Articles

Determination of Free Tryptophan in Beer Samples by Capillary Isotachophoretic Method

Tryptophan is essential amino acid and precursor for many neurotramsmiters that must be obtained from dietary proteins. However, its free form is easily absorbed and could increase the availability of this amino acid to the brain. Because of free tryptophan interaction with human health simple, eco-friendliness and low-cost method of determination are still needed. In this study, new and simple procedure for free tryptophan determination using capillary isotachophoresis is discussed. The method validation pointed good linearity, satisfactory selectivity, accuracy (recoveries varied from 98.4 to 100.1%), intra- and inter-day precision (coefficent of variation was < 5% for each standard solution and < 6% for real samples) and no matrix effect. The proposed procedure was successfully applied to analyse free tryptophan in beer samples and found contents varied from not detected to 40.74 ± 0.27 mg L−1. The obtained results were compared with chromatographic determination after derivatization with 2-chloro-1,3-dinitro-5-(trifluoromethyl)benzene and pointed better selectivity and accuracy of isotachophoretic procedure with similar precision. Due to the simplicity and flexibility, the proposed procedure is suitable for tryptophan analysis in complex matrices.

Development of a new microbial biosensor based on conductive polymer/multiwalled carbon nanotube and its application to paracetamol determination

In this study, a new microbial biosensor based on Bacillus subtilis was developed for sensitive determination of paracetamol. The microbial biosensor was modified by using carboxylated multiwalled carbon nanotube (cMWCNT) and conductive polymer, polyaniline (PANI) in presence of glutaraldehyde on a gold working electrode. Paracetamol measurements by the microbial biosensor were carried out at 0.5V applied potential with amperometric method. In the optimization studies of the microbial biosensor, the effect of (amount or concentration of) the bioactive layer components such as MWCNT, PANI, Bacillus sp. were carried out. In addition, working conditions of the microbial biosensor such as pH and temperature were also investigated.In the characterization studies of the biosensor some paramaters such as linearity, reproducibility, storage stability, substrat specificity and interference effect on the biosensor responses were determined. In the reproducibility experiments (n=7), the average value, standard deviation, (SD) and coefficent of variation (CV%) were calculated to be 250.65μM, ±1.55, 0.62% for 250μM paracetamol concentration, consecutively. Detection limit was calculated as 2.9μM by using visual evaluation mehod. In addition, paracetamol was carried out in drug samples by the developed biosensor.

The reliability of ultrasound imaging in measuring tendon size: systematic review and clinical implications

Background: Pathological tendons are known to increase their diameter, which can be viewed using ultrasound (US) and MRI. Although systematic reviews have confirmed the reliability of US for the measurement of muscle thickness, no such reviews exist to examine the reliability of US measures of tendon size. Purpose: To systematically review the literature on the reliability of US to assess tendon dimensions including thickness and cross-sectional area in human limbs. Methods: A comprehensive review of electronic databases was performed by two reviewers using an agreed range of keywords. Clinical trials which investigated inter or intra rater reliability of real time ultrasound was included in this review. The Quality Appraisal of Reliability Studies (QAREL) checklist was used to assess risk of bias. Included studies performed ultrasound analysis in a range of clinical settings. Variations existed between studies in terms of rater training, tendons studied, and participant pain status. Inter and Intra rater reliability of tendon thickness and cross sectional area were analysed using estimates of both reliability and precision using intraclass correlation coefficients (ICC’s) and coefficients of variation (CVs), percentage coefficient of variation (CV%), percentage standard error of the mean (SEM%), limits of agreement (LOA), pearsons correlation coefficient (r2) and 95% confidence intervals (95% CI). Results: A total number of 615 were included in the review. Of this 136 were Symptomatic and 479 were asymptomatic participants, with an age range: 17.5–73 years. Assessment of the risks of bias indicated 15/16 chosen studies was of high quality. ICC values for inter and intra rater reliability indicate good to excellent reliability for all tendon sites with values ranging from (0.55–0.99). Percentage coefficent of variation (CV%) ranged from 0-16% across all tendon sites. The most commonly studied tendons achilles and supraspinatus, the average measurement error from the included studies on Achilles tendons was 9.5% %CV and 5.39% SEM%, these figures equate to errors of 0.67mm and 0.32mm respectively which is well below the observed differences between symptomatic and asymptomatic tendons. The average measurement error from the included studies on supraspinatus tendons was 11.24% %CV and 5.72% SEM%, which equate to errors of 0.77mm and 0.39mm respectivelywhich is similar to, or below, the proposed differences between symptomatic and asymptomatic tendons.LOA ranged from (0.35–3.50mm), r2 ranged from (0.43–0.92), 95% CI ranged from (0.43–0.98) for all tendons. Conclusion(s): Findings of the current review appear to indicate that real time ultrasound is a clinically reliable method inmeasuring tendondimensions.However thesefindings must be considered in light of the limitations identified in the studies with a wide array of statistical methodology and wide range of measurement protocols and assessors. Implications: The findings of this current review may have important clinical implications as regards indicating future direction for possible injury prevention strategies. An understanding of the relationship between sonographic abnormalities and the likelihood of the development of symptoms in asymptomatic individuals, may allow ultrasound to be used as a screening tool to identify athletes at risk and guide prophylactic treatments or training modifications.

The effects of ocular contusion on corneal endothelium

Objective To investigate the influence of ocular contusion on corneal endothelium.Methods Twenty-seven eyes of 27 cases of ocular contusion were enrolled in the study as the clinical trial group.The contralateral healthy eyes of all cases were regarded as the control group.The corneas was measured by non-contact specular microscope.The data were analyzed by SPSS 16.0.A P value less than 0.05 was considered statistically significant.Results The corneal endothelial cell density (CD) in the experimental group (1840.80 ± 332.87)/mm2 was lower than the control group (2694.30 ± 211.32)/mm2 significantly (t =9.729,P ＜0.01).The average cell area (ACA) in the experimental group (568.16 ± 147.61) μm2 was larger than the control group (359.33 ± 69.07) μm2 significantly (t =6.463,P ＜ 0.01).The standard deviation of average area in the trial group (243.41 ± 135.45) was bigger than the control group (161.12 ± 19.00) significantly (t =4.765,P ＜ 0.01).The coefficent of variation of cell size in the trial group (41.10 ± 10.17) ％ was larger than the control group (31.01 ± 3.53) ％ significantly (t =4.915,P ＜ 0.01).The percentage of hexagonal cells (6A) of the trial group (49.88 ± 9.07) ％ was smaller than the control group (57.71 ± 5.30) ％ significantly (t =3.581,P ＜ 0.01).Conclusion Compared with the healthy eyes,corneas with ocular contusion has smaller CD and 6A,larger ACA,CV and standard deviation. Key words: Contusion, ocular; Endothelium, corneal

A comparison of the consistency of proteome quantitation using two-dimensional electrophoresis and shotgun isobaric tagging inEscherichia coli cells

An important consideration in the measurement of quantitative changes in protein expression is the consistency of the observations for a given technique as well as the reproducibility of the experiment. A quantitative assessment of the technical and biological variability is crucial to avoid erroneous inferences and conclusions. Two methods for measuring quantitative changes in protein expression are two-dimensional electrophoresis (2-DE) and shotgun proteomics of isobaric-tagged samples using iTRAQ reagents. An assessment of changes in Escherichia coli protein expression in response to rhsA induction demonstrates that half of the quantified protein expression ratios have a coefficent of variation (CV) less than 0.31 using 2-DE and less than 0.24 using isobaric tags; whereas 95% of the quantified protein expression ratios have a CV less than 0.81 using 2-DE and less than 0.53 using isobaric tags. The selective removal of outlier data points from the shotgun method using Grubb's and Rosner's statistical outlier tests improves the consistency of the quantitation data obtained.

アミオダロンおよびデスエチルアミオダロンの簡易測定法ならびにその臨床応用

A simple reverse-phase high-performance liquid chromatographic (HPLC) assay for the measurement of amiodarone and its metabolite, desethylamiodarone in the serum was established. The ODS-2 column was used and the absorbance of the effluent from the column at 254 nm was measured. The standard curves for amiodarone and desethylamiodarone were linear up to 5μg/ml. The coefficent of variation (CV) was within 10% at a concentration of 100 ng/ml, and the CV of the intra-and interday variation was within 10% at concentrations of 0.25, 0.5 and 1μg/ml, respectively. These results suggest that the limit of detection is 100 ng/ml for amiodarone and desethylamiodarone, and this assay is thus considered to be a reliable method in clinical practice. On the other hand, the serum amiodarone and desethylamiodarone concentrations were measured in 10 inpatients who received amiodarone for at least 1 month. No significant correlation was observed between the doses and serum drug concentrations. There findings therefore suggest that TDM (Therapeutic Drug Monitoring) should be performed on anyone taking amiodarone.

Local blood flow is not linked to lactate within single rabbit skeletal muscles

A marked regional distribution in blood flow within single skeletal muscles on a non-microvascular level, i.e. at the level of large arterioles or small arteries, is present in dog, cat and rabbit. The mechanism for this perfusion pattern is not known. The goal of the present study was to see if regional blood flow was correlated to regional lactate metabolism. Anesthetized rabbits were studied. Blood flow to 0.25 g muscle samples was measured with microspheres whereas lactate content and lactate dehydrogenase activity were determined in extracts of these samples. No correlation was detected between regional blood flow and regional lactate or lactate dehydrogenase either at rest or during exercise hyperemia. Expressed as the coefficent of variation (CVc), regional blood flow showed a marked scatter, the CVc ranged from 0.32 to 0.35. The corresponding CVc for both lactate and lactate dehydrogenase activity ranged from 0.16 to 0.19. It is concluded that regional blood flow is not correlated to regional lactate metabolism. The regional distribution in blood flow was markedly more uneven than that for lactate content and for lactate dehydrogenase activity.

Comparison of skewness coefficient, coefficient of variation, and Gini coefficient as inequality measures within populations.

The moment skewness coefficient, coefficient of variation and Gini coefficient are contrasted as statistical measures of inequality among members of plant populations. Constructed examples, real data examples, and distributional considerations are used to illustrate pertinent properties of these statistics to assess inequality. All three statistics possess some undesirable properties but these properties are shown to be often unimportant with real data. If the underlying distribution of the variable follows the often assumed two-parameter lognormal model, it is shown that all three statistics are likely to be highly and positively correlated. In contrast, for distributions which are not two-parameter lognormally distributed, and when the distribution is not concentrated near zero, the coefficient of variation and Gini coefficient, which are sensitive to small shifts in the mean, are often of little practical use in ordering the equality of populations. The coefficent of variation is more sensitive to individuals in the right-hand tail of a distribution than is the Gini coefficient. Therefore, the coefficient of variation may often be recommended over the Gini coefficient if a measure of relative precision is selected to assess inequality. The skewness coeficient is suggested when the distribution is either three-parameter lognormally distributed (or close to such), or when a measure of relative precision is not indicated.

Genetic Significance of the relationship between absolute total finger ridge count and its variability

In order to test the hypothesis of a major gene effect on absolute total finger ridge count (ATFRC), the nature of relationship between mean ATFRC and its variability was evaluated in a series of 47 population samples from India. Regression analysis showed that both the standard deviation and the coefficient of variation are significantly related to mean ATFRC, and about 35% of the variation in ATFRC is explained by the dependent variable coefficent of variation. These results support the hypothesis of a major gene effect on the trait ATFRC.

An improved method for the determination of adsorbed/entrapped gases in dehydrated foodstuffs

An improved method for the determination of the volume and composition (oxygen, carbon dioxide and nitrogen) of adsorbed/entrapped gases retained by dehydrated foodstuffs is described. The coefficent of variation of the method for a typical skimmed dried milk powder was 2.6%. Two general types of behaviour of foods, affecting the amount of entrapped/adsorbed gases retained by the powder upon evacuation were observed. Gas volume retained by type I powders after reaching a plateau stayed constant regardless of evacuation time, which determined the retained gas volume in type II powders.

Predicting Colorado Potato Beetle ( Leptinotarsa decemlineata Say) 1 Density and Potato Yield Loss 2

Third order exponential models are fit to 7 sets of Leptinotarsa decemlineata (Say) larval incidence data. A. predictor algorithm is developed to mimic density-related amplitude and shape changes in incidence curves. Potato Yield is related to area under the predictor curves by a linear equation. Use of the predictor to project the entire incidence curve based on a few early counts is limited by precision of the count data. This can be enhanced by using coefficent of variation and sample mean to determine proper sample size. Limitations of adult manipulation techniques for establishing larval density gradients are also discussed.