Cerebral cortex involvement in Machado-Joseph disease.

BACKGROUND AND PURPOSE: Machado-Joseph disease (MJD/SCA3) is the most frequent spinocerebellar ataxia, characterized by brainstem, basal ganglia and cerebellar damage. Few magnetic resonance imaging based studies have investigated damage in the cerebral cortex. The objective was to determine whether patients with MJD/SCA3 have cerebral cortex atrophy, to identify regions more susceptible to damage and to look for the clinical and neuropsychological correlates of such lesions. METHODS: Forty-nine patients with MJD/SCA3 (mean age 47.7 ± 13.0 years, 27 men) and 49 matched healthy controls were enrolled. All subjects underwent magnetic resonance imaging scans in a 3 T device, and three-dimensional T1 images were used for volumetric analyses. Measurement of cortical thickness and volume was performed using the FreeSurfer software. Groups were compared using ancova with age, gender and estimated intracranial volume as covariates, and a general linear model was used to assess correlations between atrophy and clinical variables. RESULTS: Mean CAG expansion, Scale for Assessment and Rating of Ataxia (SARA) score and age at onset were 72.1 ± 4.2, 14.7 ± 7.3 and 37.5 ± 12.5 years, respectively. The main findings were (i) bilateral paracentral cortex atrophy, as well as the caudal middle frontal gyrus, superior and transverse temporal gyri, and lateral occipital cortex in the left hemisphere and supramarginal gyrus in the right hemisphere; (ii) volumetric reduction of basal ganglia and hippocampi; (iii) a significant correlation between SARA and brainstem and precentral gyrus atrophy. Furthermore, some of the affected cortical regions showed significant correlations with neuropsychological data. CONCLUSIONS: Patients with MJD/SCA3 have widespread cortical and subcortical atrophy. These structural findings correlate with clinical manifestations of the disease, which support the concept that cognitive/motor impairment and cerebral damage are related in disease.

Effects of induced diabetes and the administration of aminoguanidine in the biomechanical retention of implants: a study in rats.

BACKGROUND AND OBJECTIVE: The present study aimed to assess the effects of induced diabetes and the administration of aminoguanidine in the biomechanical retention of implants in rats. MATERIAL AND METHODS: Thirty-six rats were randomly divided into six groups: group 1, healthy rats (no aminoguanidine); group 2 and group 3, healthy rats receiving 10 and 20 mg/kg of aminoguanidine daily, respectively; group 4, diabetic rats (no aminoguanidine); and group 5 and group 6, diabetic rats receiving 10 and 20 mg/kg of aminoguanidine daily, respectively. In each rat an implant was inserted in the femur. After 28 d of healing, the rats were killed. The implants were removed by applying a counter-torque, and the maximum force required for the rupture of the bone-implant interface was recorded using an analog torque meter. The data were evaluated using analysis of variance and the Student's t-test. RESULTS: In the healthy groups, no statistically significant difference could be observed in the average counter-torque values for implant removal, whereas in the diabetic groups, a daily dose of 20 mg/kg of aminoguanidine raised the counter-torque values to the values found in healthy rats. CONCLUSION: The administration of 20 mg/kg of aminoguanidine daily in diabetic rats raised the biomechanical retention of the implants to the level observed in the healthy rat group.