Francisco Páez

Increased prevalence of the seven-repeat variant of the dopamine D4 receptor gene in patients with obsessive-compulsive disorder with tics

The polymorphism characterized by a varying number of 48 bp repeats (VNTR) in the dopamine D4 receptor (DRD4) gene was examined in 61 obsessive-compulsive disorder (OCD) probands with and without tics. Most of the OCD patients with tics showed at least one copy of the 7-fold variant compared to those affected subjects without tics (91 vs. 48%, respectively, Yates corrected chi2 = 5.54, P = 0.018). Similarly, a higher number of copies of this common variant were detected in the group of probands displaying tics compared to those OCDs without tics (Yates corrected chi2 = 4.66, P = 0.03). Our study suggests that the seven-repeat allele of the DRD4 gene could be a factor in the phenotypic variance of tics among OCD individuals.

Dopamine D4 Receptor (DRD4) Gene Polymorphism in the First Psychotic Episode

BACKGROUND Dopamine D4 receptor (DRD4) has shown some interesting properties at genetic and possibly functional levels. It has been suggested that some molecular variants of the DRD4 gene (e.g., four and seven alleles) could be implicated in the pathogenesis of psychotic disorders. Additionally, the VNTR polymorphism could be implicated in part of the response to treatment with neuroleptics. This study tested the possible association between the 48-bp tandem repeats in exon 3 of the DRD4 gene and patients experiencing their first psychotic episode. METHODS Patients with a first psychotic episode (FPE, n = 37) were diagnosed and compared with a matched control group (n = 37). The FPE group was subdivided into two categories: those with nonaffective and those with affective psychoses. The variable number of tandem repeats (VNTR) region of the DRD4 gene was amplified by PCR procedures. Chi-square statistics and appropriate corrections and adjustments were used for data analysis. CONCLUSIONS A significantly lower frequency of the four repeat (4-R) carriers in the FPE group was observed. This association was sustained mainly by the affective psychotic group (chi2 = 9.99 df = 2, p = 0.0073). Although these results require testing with stringent methods, it is suggested that the DRD4-4R allele may confer some protection against psychosis, mainly of the affective subtype.

Fast Computing on Vehicle Dynamics Using Chebyshev Series Expansions

This paper focuses on faster computation techniques to integrate mechanical models in electronic advanced active safety applications. It shows the different techniques of approximation in series of functions and differential equations applied to vehicle dynamics. This allows the achievement of approximate polynomial and rational solutions with a very fast and efficient computation. First, the whole theoretical basic principles related to the techniques used are presented: orthogonality of functions, function expansion in Chebyshev and Jacobi series, approximation through rational functions, the Minimax-Remez algorithm, orthogonal rational functions, and the perturbation of dynamic systems theory, that reduces the degree of the expansion polynomials used. As an application, it is shown the obtaining of approximate solutions to the longitudinal dynamics, vertical dynamics, steering geometry, and a tyre model, all obtained through development in series of orthogonal functions with a computation much faster than those of its equivalents in the classic vehicle theory. These polynomial partially symbolic solutions present very low errors and very favorable analytical properties due to their simplicity, becoming ideal for real-time computation as those required for the simulation of evasive manoeuvres prior to a crash. This set of techniques had never been applied to vehicle dynamics before.

History of Religious Delusions and Psychosocial Functioning Among Mexican Patients with Paranoid Schizophrenia

The association between global functionality and religiosity among patients from developing and predominantly Catholic countries warrants attention. To compare religiosity and psychosocial functioning in Mexican schizophrenia patients with and without a history of religious delusions, seventy-four patients with paranoid schizophrenia were recruited. Patients with a history of religious delusions had more psychiatric hospitalizations and poorer psychosocial functioning compared with those without a history of religious delusions. No differences emerged between groups in the total scores of religiosity scales. A history of religious delusions rather than religiosity itself may have an influence on psychosocial functioning among Mexican patients with schizophrenia.