Progressive multifocal leukoencephalopathy: Serial high-b-value diffusion-weighted MR imaging and apparent diffusion coefficient measurements to assess response to highly active antiretroviral therapy

A patient with human immunodeficiency virus-related posterior fossa progressive multifocal leukoencephalopathy had serial diffusion-weighted imaging using b-values of 1000 and 3000 before and during highly active antiretroviral therapy (HAART). High-b-value images provided a superior definition of the leading edge of the lesion and additional information about the integrity of white matter tracts. Following HAART, there was a marked reduction of lesional apparent diffusion coefficient and reconstitution of anisotropy in the affected middle cerebellar peduncle

Early detection of neuropathophysiology using diffusion-weighted magnetic resonance imaging in asymptomatic cats with feline immunodeficiency viral infection

HIV infection results in a highly prevalent syndrome of cognitive and motor disorders designated as HIV-associated dementia (HAD). Neurologic dysfunction resembling HAD has been documented in cats infected with strain PPR of the feline immunodeficiency virus (FIV), whereas another highly pathogenic strain (C36) has not been known to cause neurologic signs. Animals experimentally infected with equivalent doses of FIV-C36 or FIV-PPR, and uninfected controls were evaluated by magnetic resonance diffusion weighted imaging (DWMRI) and spectroscopy (MRS) at 17.5–18 weeks postinfection, as part of a study of viral clade pathogenesis in FIV-infected cats. The goals of the MR imaging portion of the project were to determine whether this methodology was capable of detecting early neuropathophysiology in the absence of outward manifestation of neurological signs and to compare the MR imaging results for the two viral strains expected to have differing degrees of neurologic effects. We hypothesized that there would be increased diffusion, evidenced by the apparent diffusion coefficient as measured by DW-MRI, and altered metabolite ratios measured by MRS, in the brains of FIV-PPRinfected cats relative to C36-infected cats and uninfected controls. Increased apparent diffusion coefficients were seen in the white matter, gray matter, and basal ganglia of both the PPR and C36-infected (asymptomatic) cats. Thalamic MRS metabolite ratios did not differ between groups. The equivalently increased diffusion by DW-MRI suggests similar indirect neurotoxicity mechanisms for the two viral genotypes. DW-MRI is a sensitive tool to detect neuropathophysiological changes in vivo that could be useful during longitudinal studies of FIV

Multicenter linkage study of schizophrenia loci on chromosome 22q

The hypothesis of the existence of one or more schizophrenia susceptibility loci on chromosome 22q is supported by reports of genetic linkage and association, meta-analyses of linkage, and the observation of elevated risk for psychosis in people with velocardiofacial syndrome, caused by 22q11 microdeletions. We tested this hypothesis by evaluating 10 microsatellite markers spanning 22q in a multicenter sample of 779 pedigrees. We also incorporated age at onset and sex into the analysis as covariates. No significant evidence for linkage to schizophrenia or for linkage associated with earlier age at onset, gender, or heterogeneity across sites was observed. We interpret these findings to mean that the population-wide effects of putative 22q schizophrenia susceptibility loci are too weak to detect with linkage analysis even in large samples

Translational neuropsychiatry of genetic and neurodevelopmental animal models of schizophrenia

Psychiatric symptoms are subjective by nature and tend to overlap between different disorders. The modelling of a neuropsychiatric disorder therefore faces challenges because of missing knowledge of the fundamental pathophysiology and a lack of accurate diagnostics. Animal models are used to test hypotheses of aetiology and to represent the human condition as close as possible to increase our understanding of the disease and to evaluate new targets for drug discovery. In this review, genetic and neurodevelopmental animal models of schizophrenia are discussed with respect to behavioural and neurophysiological findings and their association with the clinical condition. Only specific animal models of schizophrenia may ultimately lead to novel diagnostic approaches and drug discovery. We argue that molecular biomarkers are important to improve animal to human translation since behavioural readouts lack the necessary specificity and reliability to assess human psychiatric symptoms

Recent research on geometry education: an ICME-13 survey team report

This survey on the theme of Geometry Education (including new technologies) focuses chiefly on the time span since 2008. Based on our review of the research literature published during this time span (in refereed journal articles, conference proceedings and edited books), we have jointly identified seven major threads of contributions as these relate to the early years of learning (pre-school and primary school) through to post-compulsory education and to the issue of mathematics teacher education for geometry. These themes are as follows: developments in and trends in the use of theories; advances in the understanding of spatial reasoning; the use and role of diagrams and gestures; advances in the understanding of the role of technologies; advances in the understanding of the teaching and learning of definitions; advances in the understanding of the teaching and learning of the proving process; and, moving beyond traditional Euclidean approaches. Within each theme, we identify relevant research and also offer commentary on future directions