Influence of patient personality in the treatment of rheumatoid arthritis

Individualized treatment of rheumatoid arthritis (RA) based on genetic/serologic factors is increasingly accepted. Moreover, patients are more actively involved in the management of their disease. However, personality has received little attention with respect to perception of the need and adherence to treatment. Our objective was to evaluate whether patient personality was associated with the acceptance or rejection of more aggressive early treatment. We performed a cross-sectional study in two hospitals with early arthritis clinics where sociodemographic, clinical, and therapeutic variables are systematically recorded. Patients completed Eysenck Personality Questionnaire, Multidimensional Health Locus of Control, Pain-Related Self-Statement Scale and Pain-Related Control Scale. Aggressive treatment was considered if patients received more than two DMARDs or biological agents during the first year of follow-up. Multivariate logistic regression analysis was performed to determine predictors of aggressive treatment. One hundred seventy-six RA patients were included (80 % women, disease begin median age 55 years). Treatment was considered aggressive in 57.9 % of the sample. Scores were high in extraversion in 50.8 % of patients, neuroticism in 29.5 % and psychoticism in 14.7 %. Neuroticism was the only factor associated with aggressive treatment, which was less probable (p = 0.04, OR = 0.40). Neuroticism also decreased the possibility of receiving a combination of biologics and DMARDs (p = 0.04, OR = 0.28). Patients with high scores on neuroticism are more worried, obsessive and hypochondriac, leading them to reject more aggressive therapy. It is important to educate about their disease so that they will accept more aggressive approaches in clear cases of poor outcome.     

Contributions of the N- and C-terminal domains of IGF binding protein-6 to IGF binding

Insulin-like growth factors IGF-I and IGF -II are important mediators of growth. A family of six high affinity IGF binding proteins (IGFBPs) modulate IGF action. IGFBPs have three domains, of which the N- and C-domains are involved in high affinity IGF binding. IGFBP-6 is unique in its 20-100-fold IGF-II binding specificity over IGF-I. The aim of this study was to determine the contributions of the N- and C-domains of IGFBP-6 to its IGF binding properties. We confirmed that differential dissociation kinetics are responsible for the IGF-II binding preference of IGFBP-6. The N-domain has rapid association kinetics, similar to full-length IGFBP-6, but both IGF-I and -II dissociate rapidly from this domain, thereby reducing its binding affinity for IGF-II approximately 50-fold. However, the N-domain binds IGF-I and -II with similar affinities and it has a similar IGF-I binding affinity to full-length IGFBP-6. This suggests that the C-domain confers the IGF-II binding preference of IGFBP-6; indeed, IGF-I bound inconsistently with very low affinity to the C-domain. Coincubation studies showed that isolated N- and C-domains of IGFBP-6 do not strongly cooperate to enhance IGF binding. The results of the binding studies are supported by the effects of the IGFBP-6 domains on IGF-induced colon cancer cell proliferation; the N-domain inhibited IGF-II induced proliferation with approximately 20-fold lower potency than IGFBP-6 and it was equipotent in inhibiting IGF-I- and IGF-II-induced proliferation. Coincubation of C-domain had no additional effect on N-domain-induced inhibition of proliferation. In conclusion, both the N- and C-domains of IGFBP-6 are involved in IGF binding, the C-domain is responsible for the IGF-II binding preference of IGFBP-6 and intact IGFBP-6 is necessary for high affinity IGF binding.     

Associations between the leptin receptor gene and adiposity in middle-aged Caucasian males from the HERITAGE family study

Linkage and association studies between three exonic polymorphisms in the leptin receptor gene and body composition variables in the HERITAGE Family Study were undertaken. Polymorphisms K109R, Q223R, and K656N have been analyzed with body mass index (BMI), sum of height skinfolds (SF8), fat mass (FM), percent body fat (%FAT), fat free mass, and plasma leptin level. Single-point linkage analysis and covariance analysis across genotypes were performed, by race, on phenotypes adjusted for age and sex. Blacks (88 parents; 231 adult offspring) from 115 nuclear families (72-119 sibpairs) and Caucasians (192 parents; 330 adult offspring) from 99 nuclear families (319-364 sibpairs) were used for these analyses. In Caucasians, BMI and FM showed suggestive linkages with K109R (P = 0.02 and P = 0.05, respectively) and associations with Q223R (P = 0.005 and P = 0.03, respectively). In blacks, no statistically significant linkage or association was observed. In Caucasians, associations with Q223R were observed in parents, but not in offspring, for BMI, FM, and %FAT (0.04< or =P< or =0.0001). Males, not females, showed differences across genotypes for the same phenotypes plus SF8 and leptin (0.03< or = P< or =0.0002). Carriers of the R223 allele showed higher values than noncarriers for BMI (+4 U, P = 0.0001), SF8 (+30 mm, P = 0.01), FM (+7 kg, P = 0.0004), %FAT (+5%, P = 0.0002), and leptin (+4 ng/mL, P = 0.0006). These results indicate a significant effect of leptin receptor on adiposity in middle-aged Caucasian males.