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PubMed2002

[French validation of the revised Piper Fatigue Scale].

The need for a valid and reliable multi-dimensional instrument in French to enable nurses and clinicians to assess intensity and changes in cancer-related fatigue (CRF) and evaluate efficacy of intervention stratégies on patient outcome, prompted us to translate the Piper Fatigue Scale (PFS) and assess its psychometric properties in a French speaking population. The revised PFS is a 22 item self-report instrument with four sub-scales: behavioural/severity, affective, sensory and cognitive/mood. The PFS was translated using a procédure of translation and back translation and tested on 20 bilingual subjects. Correlation coefficients were measured between the item scores of the English and French version of the PFS. The French version of the PFS was adjusted and then completed by 229 adult cancer patients with solid tumours under-going treatment by chemo-, radio-, hormono- or immunotherapy. A factorial analysis and a multi-traits analysis were used to assess the reliability and the dimensional structure of the translated version of the PFS. Cronbach's alpha correlations ranged between 0.85 and 0.92 for the various sub-scales, thus indicating good sub-scale reliability. Item internal consistency was good with 100% of item-scale correlations greater than or equal to 0.4. Item discriminant validity checking showed 3 items to be insufficiently discriminating. Item-scale correlations greater than the correlation of the item with other sub-scales were 98%. The Cognitive/Mood dimension appeared to group 2 separate dimensions. Convergent validity, tested by correlating the PFS with a Visual Analogue Scale measuring fatigue and with the OMS Physical Performance Status Scale, revealed significant relationships. A five sub-scale model of the PFS is proposed containing 22 items to increase performance of the French version of the PFS comparatively to the 4 sub-scale model of the original PFS. Translation of 2 items has been slightly modified to reduce ambiguity. The overall results of this preliminary study are satisfactory. We expect results to be further improved by the modifications proposed and testing is now underway in homogenous populations to evaluate the sensitivity of the instrument to changes over time. This will enable us to ascertain the definitive French version of the Piper Fatigue Scale.

Activities of Daily Living↗

PubMed2002

A statistical model for the genetic origin of allometric scaling laws in biology.

Many biological processes, from cellular metabolism to population dynamics, are characterized by particular allometric scaling (power-law) relationships between size and rate. Although such allometric relationships may be under genetic determination, their precise genetic mechanisms have not been clearly understood due to a lack of a statistical analytical method. In this paper, we present a basic statistical framework for mapping quantitative genes (or quantitative trait loci, QTL) responsible for universal quarter-power scaling laws of organic structure and function with the entire body size. Our model framework allows the testing of whether a single QTL affects the allometric relationship of two traits or whether more than one linked QTL is segregating. Like traditional multi-trait mapping, this new model can increase the power to detect the underlying QTL and the precision of its localization on the genome. Beyond the traditional method, this model is integrated with pervasive scaling laws to take advantage of the mechanistic relationships of biological structures and processes. Simulation studies indicate that the estimation precision of the QTL position and effect can be improved when the scaling relationship of the two traits is considered. The application of our model in a real example from forest trees leads to successful detection of a QTL governing the allometric relationship of third-year stem height with third-year stem biomass. The model proposed here has implications for genetic, evolutionary, biomedicinal and breeding research.

Animals↗

PubMed1992

[The genetic analysis of long-term index selection--a simulation experiment].

The genetic effects of long-term index selection were investigated by means of Monte Carlo Method. The response and the effect on genetic structure of population to selection using four methods, that is theoretical index, emperical index, restricted index and single-trait selection, were compared. Results obtained from 50 generations demonstrated that much greater response was achieved in large populations, and selection in small ones led to a decrease in selection limit. Genetic correlation played an important role on response in small populations. Emperical index selection was more effective than theoretical index, restricted index had less response in the early period of selection but greater response in later period and also had less effect on genetic structure of population even if the genetic correlation was intense. Meanwhile, index selection could cause decrease in additive genetic variance and beritabilities while genetic correlation changed depending on the coefficients of index formulae. The suggestion is that emperical index or restricted index should be used for long-term selection for multi-traits.

Computer Simulation↗

PubMed2004

Psychometric validation of the French version of the quality of life in epilepsy inventory (QOLIE-31): comparison with a generic health-related quality of life questionnaire.

A psychometric evaluation of a French transcultural version of the quality of life in epilepsy inventory-31 (QOLIE-31) was carried out. QOLIE-31 was compared to a generic health-related quality of life questionnaire, the Nottingham health profile (NHP). The psychometric properties of QOLIE-31, assessed in 190 adults with epilepsy, included: acceptability, test-retest reliability and validity (multi-trait analysis including internal consistency and item-to-scale correlations, construct validity using factor analysis, discriminative validity using relationship with disease characteristics, treatment effects, divergent and convergent validity using correlations with NHP scores). Both acceptability and reproducibility were good and internal consistency was high (Cronbach's alpha coefficient = 0.86). Factor analysis with varimax rotation identified seven factors with eigenvalues > 1, with two factors, related to cognitive function and mood, accounting for 46.5% of the variance. However, goodness of fit indices revealed that a model with four factors best fitted the data. The first factor corresponds to a generic mental dimension, the second is equivalent to the cognitive functioning dimension, the third to medication effects including social functioning, and the fourth to seizure worry. Discriminative validity was good for seizure control and treatment tolerability. High correlations between QOLIE-31 and pertinent NHP scales (emotional reactions, energy and social isolation) were observed. The French version of QOLIE-31 thus meets established psychometric criteria for reliability and validity.

Activities of Daily Living↗

PubMed2006

Estimation of genetic parameters for a new model for defining body structure scores (frame scores) in Nellore cattle.

Models for estimation of frame scores in Nellore beef cattle (FRAME_GMA) were developed, comparing them with frame scores estimated using equations proposed by the Beef Improvement Federation (FRAME_BIF, USA). Correlation among frame scores obtained by these two methodologies, along with the independent variables considered in the estimation models, were also studied. A data set with 12,728 animals, with ages between 490 and 610 days, was used. The models that best adjusted to FRAME_GMA included hip height, weight and interaction between height and weight. Estimates of heritability for FRAME_GMA and FRAME_BIF were 0.26 +/- 0.03 and 0.23 +/- 0.03, respectively, in single trait analysis, and 0.28 and 0.24, respectively, in multi-trait analysis. Phenotypic Pearson and Spearman correlation coefficients between FRAME_GMA and FRAME_BIF for males were 0.87 and 0.83, respectively, being lower than those found for females (0.92 for both coefficients). Genetic correlation between the frame scores did not differ between genders, with values of 0.92 for the Pearson coefficient and 0.91 for the Spearman coefficient. We concluded that FRAME_GMA was better adapted to this data set than FRAME_BIF. Other studies need to be made to evaluate the applicability of this proposed model to other populations of Nellore beef cattle and for other age groups.

Animals↗