Deletion of the mental retardation gene Gdi1 impairs associative memory and alters social behavior in mice

Non-specific mental retardation (NSMR) is a common human disorder characterized by mental handicap as the only clinical symptom. Among the recently identified MR genes is GDI1, which encodes alpha Gdi, one of the proteins controlling the activity of the small GTPases of the Rab family in vesicle fusion and intracellular trafficking. We report the cognitive and behavioral characterization of mice carrying a deletion of Gdi1. The Gdi1-deficient mice are fertile and anatomically normal. They appear normal also in many tasks to assess spatial and episodic memory and emotional behavior. Gdi1-deficient mice are impaired in tasks requiring formation of short-term temporal associations, suggesting a defect in short-term memory. In addition, they show lowered aggression and altered social behavior. In mice, as in humans, lack of Gdi1 spares most central nervous system functions and preferentially impairs only a few forebrain functions required to form temporal associations. The general similarity to human mental retardation is striking, and suggests that the Gdi1 mutants may provide insights into the human defect and into the molecular mechanisms important for development of cognitive functions.     

Lack of association between angiotensin converting enzyme polymorphism and sporadic Alzheimer's disease

Epidemiological and pathogenetic evidences suggest a strong association between vascular risk factors and sporadic Alzheimer's disease (sAD). In agreement with the vascular hypothesis of AD, the role of various candidate genes for atherosclerosis has been investigated, leading to conflicting results. In order to clarify the significance of angiotensin-converting enzyme (ACE) gene insertion (I)/deletion (D) polymorphism in a group of patients with sAD, we conducted a case-control study including 149 cases and 149 age and sex matched controls. All subjects were genotyped for ACE and Apolipoprotein E (APOE). There were no significant differences in ACE genotype or allele frequencies between cases and controls, even after stratification for APOE4 carrier status. Our data suggest that the ACE I/D polymorphism is not associated to genetic susceptibility in sAD patients.     

Aberrant cellular retinol binding protein 1 (CRBP1) gene expression and promoter methylation in prostate cancer

AIMS: Retinoids are involved in cell growth, differentiation, and carcinogenesis. Their effects depend on cytosolic transport and binding to nuclear receptors. CRBP1 encodes a protein involved in this process. Because altered CRBP1 expression and promoter hypermethylation occur in several tumours, these changes were investigated in prostate tumorigenesis. METHODS: The CRBP1 promoter was assessed by methylation specific polymerase chain reaction on tissue samples from 36 radical prostatectomy specimens (paired normal tissue, adenocarcinoma, and high grade prostatic intraepithelial neoplasia (HGPIN)), 32 benign prostatic hyperplasias (BPHs), and 13 normal prostate tissue samples from cystoprostatectomies. Methylation of DNA extracted from microdissected tissue was examined blindly. CRBP1 expression was assessed by immunohistochemistry on formalin fixed, paraffin wax embedded tissue. RESULTS: Loss of CRBP1 expression was seen in 15 of 36 adenocarcinomas and 18 of 36 HGPINs. Fifteen adenocarcinomas and nine HGPINs showed overexpression, whereas the remainder showed normal expression. BPH displayed normal expression. No significant associations were found between CRBP1 expression and Gleason score or stage. CRBP1 promoter hypermethylation was found in 17 of 36 adenocarcinomas, three of 35 HGPINs, one of 36 normal prostate tissues from the same patients, none of 32 BPHs, and none of 13 normal prostate tissues from cystoprostatectomies. Loss of expression and hypermethylation of CRBP1 were not significantly associated. CONCLUSIONS: Altered CRBP1 expression and hypermethylation are common in prostate carcinoma, although CRBP1 hypermethylation is not an early event in tumorigenesis. Moreover, both adenocarcinoma and HGPIN show frequent CRBP1 overexpression. The molecular mechanisms underlying altered CRBP1 expression in prostate cancer deserve further study.     

Characterization of a bovine collagen-hydroxyapatite composite scaffold for bone tissue engineering

Different biomaterials have been used as scaffolds for bone tissue engineering. Here we characterize a biomaterial composed of sintered (1100 degrees C) and powdered hydroxyapatite (HA) and type I collagen (Coll), both of bovine origin, designed for osteoconductive and osteoinductive scaffolds. Coll/HA proportions were 1/2.6 and 1/1 (wet weight), and particles sizes varied from 200 to 400 microm. Vv (volume density) and Sv (surface to volume density) for the HA particles in the composite ranged from 0.48 +/- 0.06 to 0.55 +/- 0.02 and 5.090 +/- 0.545 to 6.366 +/- 0.289 microm(-1), respectively. Due to the relatively small changes in Vv and Sv, a macroporosity could be characterized for the biocomposite. X-ray diffraction and infrared spectroscopy showed that the sintered bone was composed essentially of HA with minimum additional groups such as surface calcium hydroxide, surface and crystal water, free carbon dioxide and possibly brushite. Mass spectrometry detected carbonates at A and B sites of HA, and weakly bound to the structure. Human osteoblasts adhered and spread on both the HA particle surface and the collagen fibers, which seemed to guide cells between adjacent particles. The biocomposite studied has several characteristics considered as ideal for its use as a scaffold for osteoconduction and osteoinduction.     

Choroidal vasculature in diabetic rats

This study aims to evaluate the diabetic influence on the choroidal vessels morphology. Twenty Wistar rats were divided into a control (CG) and a diabetic group (DG). The animals had the diabetes induced by an intra-venous injection of Alloxan (42 mg/kg). Transmission electron microscopy analysis focusing the choroidal vessels was done one (T2) and twelve (T3) months after the diabetes induction. The CG rats in T3 showed vesicles and dense bodies in the endothelial and pericytic cells; the same structures were observed in the DG at T2. The DG rats in T3 had even more and intense changes than the T2DG rats. The morphological evaluation indicates that the choroidal vessels are affected in diabetes and the disease accelerates degenerative processes in the rat choroidal vasculature.     

Electromyographic validation of the pectoralis major and deltoideus anterior muscles in inverted "flying" exercises with loads

Inverted 'flying" exercise with external loads of 25, 50, 75 and 100% of each individual maximum load in the pectoralis major and deltoideus anterior muscles was electromyographically analyzed in eleven male volunteers, using surface electrodes MEDI-TRACE-200 connected to a biological signals acquisition module coupled to a PC/AT computer. Electromyographic signals were processed and the effective values obtained were standardized through maximum voluntary isometric contraction. When the concentric phase of each muscle with the same load was statistically compared with the eccentric phase, it was observed that for all loads all the muscles presented significant electromyographic difference, and that the concentric phase was always higher. By analyzing the different loads for each muscle, it was noticed that in the concentric phase all the muscles presented significant electromyographic activity, being it higher with maximum load. When the effect of each load on different muscle in the concentric and eccentric phases was analyzed, the muscles presented a distinct activity profile.     

On the mechanisms of genotoxicity and metabolism of quercetin

Quercetin has been the subject of numerous studies on its genetictoxicity and carcinogenicity. Despite its well-proven geneticdamaging activity for various genetic end-points (reverse mutations,induction of SOS functions, induction of sister chromatid exchanges,chromosomal aberrations and micronuclei), the mechanisms ofgenetic damage by quercetin remain, by and large, unknown. Thepresent study aims to further extend the observations on thepossible active oxygen species mediated DNA-damaging activityof quercetin and the role of cytochrome P450-dependent metabolismon the genotoxicity of quercetin. The results reported in thiswork show that querceitn can produce the OH radical, as assessedby deoxyribose degradation in the presence of Fe^3³/EDTA(ethylenediaminetetraacetic acid), and that it induces strandbreakage in isolated plasmidic DNA (pUC18). The data supportthe hypothesis that the production of OH is mediated by H₂O₂.The results with genetically engineered V79 cells expressingrat cytochromes 1A1, 1A2 and 2B1 failed to demonstrate metabolismof quercetin, as indicated by the fact that neither an enhancementnor a decrease in the genotoxicity of quercetin was observed.Results obtained on the pH dependence of the induction of chromosomalaberrations by quercetin in V79 cells show that, as the valueof the medium is increased to 8.0, there is a significant increasein the number of aberrant cells, as expected if oxygen radicalsare responsible for the formation of chromosomal aberrations. ³To whom correspondence should be addressed