Validation interne de la version française du NEO-PI-R et influence de l'âge, du sexe et de la profession

We have examined the internal validity of the French translation of the NEO PI-R personality test which measures the « big five » (Rolland, 1993). The impact of age, gender and professional categories on the NEO PI-R scales was assessed. A large sample (n=731) of subjects of different age, gender and profession and a sample of Swiss students (n=261) responding anonymously were used. Factor analyses confirmed the structure of the instrument (5 domains) and the structures of the domains in terms of facets (six facets within each domain). On the other hand, the age has a significant impact on all the domains of the NEO PI-R; the gender has an impact on the scores on N (neuroticism), O (openness) and A (agreeableness), and the profession has an impact on the domains E (extraversion), O (openness) and A (agreeableness). The scores on several facets are also affected by those three variables. Our study gives the researchers and the practitioner a reference score table according to the studied variables.

The hierarchical structures of the NEO-PI-R and the 16PF5

The present study compares the higher-level dimensions and the hierarchical structures of the fifth edition of the 16 PF with those of the NEO PI-R. Both inventories measure personality according to five higher-level dimensions. These inventories were however constructed according to different methods (bottom-up vs. top-down). 386 participants filled out both questionnaires. Correlations, regressions and canonical correlations made it possible to compare the inventories. As expected they roughly measure the same aspects of personality. There is a coherent association among four of the five dimensions measured in the tests. However Agreeableness, the remaining dimension in the NEO PI-R, is not represented in the 16 PF 5. Our analyses confirmed the hierarchical structures of both instruments, but this confirmation was more complete in the case of the NEO PI-R. Indeed, a parallel analysis indicated that a four-factor solution should be considered in the case of the 16 PF 5. On the other hand, the NEO PI-R's five-factor solution was confirmed. The top-down construction of this instrument seems to make for a more legible structure. Of the two five-dimension constructs, the NEO PI-R thus seems the more reliable. This confirms the relevance of the Five Factor Model of personality.

Comparison of the NEO-FFI, the NEO-FFI-R and an alternative short version of the NEO-PI-R (NEO-60) in Swiss and Spanish samples

Three different short versions of the NEO-PI-R were compared: The NEO-FFI, the NEO-FFI-R, and a new short version developed in the current study (NEO-60). This new version is intended to improve the psychometric characteristics of the original NEO-FFI, specially in regard to the factor structure at the item-level. A French version of the NEO-PI-R was given to 1090 Swiss subjects, whereas the Spanish (Castilian) version of the NEO-PI-R was administered to 1006 Spanish subjects. Results replicate the limitations of the NEO-FFI already found in other countries. Compared to the NEO-FFI, reliability coefficients and factor structure was enhanced by the NEO-FFI-R and the NEO-60 in both samples, although substantial differences were not found. The factor structure of the NEO-60 shows the best fit since only three items do not load mainly on their own factor in both samples. Besides, correlations between items and NEO-PI-R domain scores are also higher for the items included in the NEO-60 version. On the other hand, convergent correlations with the NEO-PI-R dimensions were satisfactory irrespective of the version, and confirmatory factor analyses show slight differences among the different models generated after the three short versions.

The 16PF5 and the NEO-PI-R in Spanish and Swiss samples: A cross-cultural comparison

This study compared the Spanish (Castilian) and French versions of the 16PF5 and of the NEO-PI-R in Spanish and Swiss samples. The five-factor solution for the 16PF5 only seems clear for the Castilian version, but not for the French version. Indeed, the congruence coefficients for the Tough-Mindedness and the Self-Control dimensions are low. On the other hand, the five-factor solutions are highly similar for both countries concerning the NEO-PI-R, and the congruence coefficients are above .95 for all five dimensions. The low cross-cultural replicability for the 16PF5 makes it difficult to analyze the differences at the mean level for this inventory. For the NEO-PI-R, the differences are generally very small and globally account for 2.6% of the total variance. Spaniards seem to have slightly lower scores on Actions and slightly higher scores on Dutifulness. These differences could either be due to translation problems, sample selection, or cultural differences.

Rab18 dynamics in adipocytes in relation to lipogenesis, lipolysis and obesity.

Lipid droplets (LDs) are organelles that coordinate lipid storage and mobilization, both processes being especially important in cells specialized in managing fat, the adipocytes. Proteomic analyses of LDs have consistently identified the small GTPase Rab18 as a component of the LD coat. However, the specific contribution of Rab18 to adipocyte function remains to be elucidated. Herein, we have analyzed Rab18 expression, intracellular localization and function in relation to the metabolic status of adipocytes. We show that Rab18 production increases during adipogenic differentiation of 3T3-L1 cells. In addition, our data show that insulin induces, via phosphatidylinositol 3-kinase (PI3K), the recruitment of Rab18 to the surface of LDs. Furthermore, Rab18 overexpression increased basal lipogenesis and Rab18 silencing impaired the lipogenic response to insulin, thereby suggesting that this GTPase promotes fat accumulation in adipocytes. On the other hand, studies of the β-adrenergic receptor agonist isoproterenol confirmed and extended previous evidence for the participation of Rab18 in lipolysis. Together, our data support the view that Rab18 is a common mediator of lipolysis and lipogenesis and suggests that the endoplasmic reticulum (ER) is the link that enables Rab18 action on these two processes. Finally, we describe, for the first time, the presence of Rab18 in human adipose tissue, wherein the expression of this GTPase exhibits sex- and depot-specific differences and is correlated to obesity. Taken together, these findings indicate that Rab18 is involved in insulin-mediated lipogenesis, as well as in β-adrenergic-induced lipolysis, likely facilitating interaction of LDs with ER membranes and the exchange of lipids between these compartments. A role for Rab18 in the regulation of adipocyte biology under both normal and pathological conditions is proposed.