Bradford Armando Navia, MD, PhD - US grants

X-linked Retinitis Pigmentosa is one of the most sever e of the hered- itary causes of blindness in man, yet its biochemical basis remains un- known. Recent linkage data indicate the existence of two distinct loci, both regionalized to the proximal short arm of the X chromosome: one at Xp (RP3) and the other more proximal linked to DXS7 (RP2). This research proposal aims to clone and characterize the gene for RP3 and define further the chromosomal localization of the RP2 locus. To isolate the RP3 gene, genomic clones recently obtained from the region between the CGD locus and JBB will be analyzed further in order to identify conserved sequences indicative of exon containing sequences and to detect either microdeletions or rearrangements in DNA panels of unrelated males with XRP by either Southern blot analysis or pulse field gel electrophoresis. Additional clones that map close to or within the RP3 locus will be iso- lated by bidirectional chromosomal walking from the nearest flanking markers in phage libraries and by analysis of already obtained Yeast Artificial Chromosome (YAC) clones that contain sequences from this region. Clones that detect conserved sequences will be used to isolate candidate RP3 cDNAs which will be further characterized by Northern analysis and sequencing. Once a candidate sequence had been found, future efforts will be targeted towards identifying mutations at the RP3 locus, elucidating the structural organization of the gene and developing reagents to study the cellular and biochemical properties of the RP3 protein. To localize more precisely the RP2 locus a detailed long range restriction map that will link up regions between DXS7 and DXS255 and identify HTF islands will be developed with the aim of identifying the restriction fragment that contains the RP2 gene.

DESCRIPTION (provided by applicant): Highly active antiretroviral therapy (HAART) has resulted in a marked rise in survival rates among HIV-infected persons. To what extent the brain compartment benefits from such treatment, particularly in the setting of advanced, even stable, disease, remains unclear. Recent studies suggest that cerebral injury and neurocognitive impairment can persist or unfold in the setting of HAART and stable disease. The frequency, spectrum and extent of neurological injury, its relationship to cognitive functioning and responsiveness to antiretroviral therapies thus remain important yet unresolved issues. The HIV MRS consortium has identified regional and cellular abnormalities specific to different stages of HIV-associated cognitive impairment (AIDS dementia complex, ADC) as well as an in vivo model of brain injury that suggests basal ganglia and neuronal events may be critical to the development of ADC. It has also identified potential host (e.g. age, plasma MCP-1, CSFIP-10, CSF fractalkine) and viral factors (CSF HIV RNA) at baseline that may increase the risk for neurocognitive impairment (NCI) or its further decline. This is a five-year multicenter longitudinal study of cerebral injury (as measured by MRS) and NCI in 310 HIV-positive subjects with a history of advanced immunosuppression (nadir CD4<100/mL) on HAART. The study will fill an important gap in the literature by implementing MRS in a prospective design in order to identify subjects at risk for NCI. We will examine the pattern and dynamics of regional injury by MRS among 250 neurologically asymptomatic (NA) and 60 ADC subjects. The majority of subjects will be enrolled from three well characterized existing prospective cohorts, including two ACTG studies (N= 210) and from the brain bank studies UCLA NNAB and UCSD CNTN (N= 100). Subjects will be stratified by CD4 count at entry, <200 or >200 cells/ml. The brain bank subjects will be further divided into virologically suppressed and nonsuppressed groups. The primary aims are: 1) to identify NA subjects at risk for brain injury as measured by MRS and examine host (e.g. age, chemokines) and viral factors (HIV RNA) at baseline that may increase the risk for subsequent neurological injury and NCI;2) to determine whether the emergence of basal ganglia and neuronal factors predict the onset of NCI or its progression;3) to examine dynamic relationships between neurologic function, biomarkers that reflect changing virologic and immunologic activity and changes in treatment. Multivariate longitudinal models and variable selection will be used to study the neurological effects of HIV infection as a dynamic system of interrelated factors. Detection of brain injury among NA subjects on HAART and at risk for ADC will have critical ramifications for overall health outcome and early therapeutic intervention.

[unreadable] DESCRIPTION (provided by applicant): The present proposal is a supplement to the recently funded NeuroHIV Magnetic Resonance Spectroscopy Consortium grant (PI: Navia R01NS036524-05). The parent grant is a longitudinal study of brain metabolite changes and cognitive impairment associated with advancing HIV disease in the era of anti-retroviral therapy (ART). This supplement aims to support state-of-the-art longitudinal analyses of the structural MRI data that is automatically collected as part of the parent consortium grant. The present study will allow us to identify multiple MRI signatures of brain dysfunction associated with HIV, and in turn define the evolutionary stages of brain involvement in HIV. ART has dramatically improved survival rates among HIV patients, though the extent to which these agents provide lasting benefits to the brain remains unresolved. There is accumulating evidence that despite good peripheral viral suppression, a significant amount of HIV-associated brain injury continues to occur. In vivo volumetric magnetic resonance imaging (MRI) provides a sensitive measure of regional and specific HIV- associated brain abnormalities. The MRS Consortium is collecting neuroimaging, immunological/virological and cognitive data from 310 HIV subjects with a history of advanced HIV disease on stable ART and at different stages of immunological and neurocognitive compromise. Follow-up assessments occur every 26-32 weeks (including MRI). The T1 and dual echo (proton density/T2) sequences from each time point will be analyzed using semi-automated methods including segmentation, voxel based morphometry and automatic anatomical labeling in order to ascertain the extent and severity morphometric change in treated HIV patients. The primary aims include: 1) To examine the evolution/progression of brain parenchymal fraction (BPF), frontal lobe, basal ganglia, hippocampal, and corpus callosum atrophy associated with HIV infection relative to MRS markers of inflammation (Ml/Cr, and Cho/Cr) and neuronal health (NAA/Cr); 2) To assess the temporal relationships between change in MRS measures, volumetric loss, and progression of cognitive impairment; and 3) To identify host and viral factors (e.g., age, CD4 count, chemokines, and HIV RNA) that may predict risk for structural brain atrophy. We propose to derive multivariate longitudinal models and examine the CMS effects of HIV as a dynamic system of interrelated factors. The establishment of neuroanatomical sequelae among HIV subjects on ART will have critical ramifications for cognitive outcome as well as provide additional targets for therapeutic outcome. [unreadable] [unreadable] [unreadable]