Cerebrospinal fluid flow dynamics in Huntington's disease evaluated by phase contrast MRI

Multiple targeted therapeutics for Huntington's disease are now in clinical trials, including intrathecally delivered compounds. Previous research suggests that CSF dynamics may be altered in Huntington's disease, which could be of paramount relevance to intrathecal drug delivery to the brain. To test this hypothesis, we conducted a prospective cross‐sectional study comparing people with early stage Huntington's disease with age‐ and gender‐matched healthy controls. CSF peak velocity, mean velocity and mean flow at the level of the cerebral aqueduct, and sub‐arachnoid space in the upper and lower spine, were quantified using phase contrast MRI. We calculated Spearman's rank correlations, and tested inter‐group differences with Wilcoxon rank‐sum test. Ten people with early Huntington's disease, and 10 controls were included. None of the quantified measures was associated with potential modifiers of CSF dynamics (demographics, osmolality, and brain volumes), or by known modifiers of Huntington's disease (age and HTTCAG repeat length); and no significant differences were found between the two studied groups. While external validation is required, the attained results are sufficient to conclude tentatively that a clinically relevant alteration of CSF dynamics – that is, one that would justify dose‐adjustments of intrathecal drugs – is unlikely to exist in Huntington's disease.     

Developing a culture of nursing research through clinical-academic partnership

Evidence based practice is essential to advanced practice nursing, enabling the delivery of quality care and improved patient outcomes. As the name suggests, it requires healthcare decisions to be based on the best available and current evidence. Advanced practice nurses need astute critical analysis skills to appraise the evolving literature, and require research skills to lead on scientific inquiry and develop the profession. Yet, advanced practice nurses may not recognize themselves as research leaders. Participation in a journal club can promote evidence-based practice, improve clinician's critical thinking skills, and expose members to different research methodologies, however, nurses continue to face barriers to participation in these clubs. Establishing a clinical-academic partnership appears to be both mutually beneficial for clinicians and academics and is a significant enabler in the sustainability and functioning of the club through sharing expertise and experience. A supportive workplace culture is favourable to research utilization and knowledge translation. This paper outlines the role, practicalities, challenges, and benefits of setting up a hybrid urology journal and research club for advanced practice nurses in a clinical-academic partnership.     

Differential gene expression in ovarian carcinoma: identification of potential biomarkers

Ovarian cancer remains the fifth leading cause of cancer death for women in the United States. In this study, the gene expression of 20 ovarian carcinomas, 17 ovarian carcinomas metastatic to the omentum, and 50 normal ovaries was determined by Gene Logic Inc. using Affymetrix GeneChip HU_95 arrays containing approximately 12,000 known genes. Differences in gene expression were quantified as fold changes in gene expression in ovarian carcinomas compared to normal ovaries and ovarian carcinoma metastases. Genes up-regulated in ovarian carcinoma tissue samples compared to more than 300 other normal and diseased tissue samples were identified. Seven genes were selected for further screening by immunohistochemistry to determine the presence and localization of the proteins. These seven genes were: the beta8 integrin subunit, bone morphogenetic protein-7, claudin-4, collagen type IX alpha2, cellular retinoic acid binding protein-1, forkhead box J1, and S100 calcium-binding protein A1. Statistical analyses showed that the beta8 integrin subunit, claudin-4, and S100A1 provided the best distinction between ovarian carcinoma and normal ovary tissues, and may serve as the best candidate tumor markers among the seven genes studied. These results suggest that further exploration into other up-regulated genes may identify novel diagnostic, therapeutic, and/or prognostic biomarkers in ovarian carcinoma.     

Haplotype structure,LD blocks,and uneven recombination within the LRP5 gene

Patterns of linkage disequilibrium (LD) in the human genome are beginning to be characterized, with a paucity of haplotype diversity in "LD blocks," interspersed by apparent "hot spots" of recombination. Previously, we cloned and physically characterized the low-density lipoprotein-receptor-related protein 5 (LRP5) gene. Here, we have extensively analysed both LRP5 and its flanking three genes, spanning 269 kb, for single nucleotide polymorphisms (SNPs), and we present a comprehensive SNP map comprising 95 polymorphisms. Analysis revealed high levels of recombination across LRP5, including a hot-spot region from intron 1 to intron 7 of LRP5, where there are 109 recombinants/Mb (4882 meioses), in contrast to flanking regions of 14.6 recombinants/Mb. This region of high recombination could be delineated into three to four hot spots, one within a 601-bp interval. For LRP5, three haplotype blocks were identified, flanked by the hot spots. Each LD block comprised over 80% common haplotypes, concurring with a previous study of 14 genes that showed that common haplotypes account for at least 80% of all haplotypes. The identification of hot spots in between these LD blocks provides additional evidence that LD blocks are separated by areas of higher recombination.     

Practice guidelines for the molecular analysis of Prader-Willi and Angelman syndromes

Background

Asthma is a chronic respiratory disease whose genetic basis has been explored for over two decades, most recently via genome-wide association studies. We sought to find asthma-susceptibility variants by using probands from a single population in both family-based and case-control association designs.

Methods

We used probands from the Childhood Asthma Management Program (CAMP) in two primary genome-wide association study designs: (1) probands were combined with publicly available population controls in a case-control design, and (2) probands and their parents were used in a family-based design. We followed a two-stage replication process utilizing three independent populations to validate our primary findings.

Results

We found that single nucleotide polymorphisms with similar case-control and family-based association results were more likely to replicate in the independent populations, than those with the smallest p-values in either the case-control or family-based design alone. The single nucleotide polymorphism that showed the strongest evidence for association to asthma was rs17572584, which replicated in 2/3 independent populations with an overall p-value among replication populations of 3.5E-05. This variant is near a gene that encodes an enzyme that has been implicated to act coordinately with modulators of Th2 cell differentiation and is expressed in human lung.

Conclusions

Our results suggest that using probands from family-based studies in case-control designs, and combining results of both family-based and case-control approaches, may be a way to augment our ability to find SNPs associated with asthma and other complex diseases.     

CD1a-autoreactive T cells are a normal component of the human αβ T cell repertoire

CD1 activates T cells, but the function and size of the possible human T cell repertoires that recognize each of the CD1 antigen-presenting molecules remain unknown. Using an experimental system that bypasses major histocompatibility complex (MHC) restriction and the requirement for defined antigens, we show that polyclonal T cells responded at higher rates to cells expressing CD1a than to those expressing CD1b, CD1c or CD1d. Unlike the repertoire of invariant natural killer T (NKT) cells, the CD1a-autoreactive repertoire contained diverse T cell antigen receptors (TCRs). Functionally, many CD1a-autoreactive T cells homed to skin, where they produced interleukin 22 (IL-22) in response to CD1a on Langerhans cells. The strong and frequent responses among genetically diverse donors define CD1a-autoreactive cells as a normal part of the human T cell repertoire and CD1a as a target of the T(H)22 subset of helper T cells.     

Microstructural Characteristics of Extracellular Matrix Produced by Stromal Fibroblasts

The overall objective of this investigation was to characterize the extracellular matrix deposited by the stromal fibroblasts as a function of time in culture and matrix microstructure. Stromal fibroblasts were seeded onto collagen matrices and cultured for up to 5 weeks. The collagen matrices contained collagen fibrils with an average diameter of 215 ± 20 nm. When cultured on a collagen film, an average fibril diameter of 62 ± 39 nm was observed for single layer films with only slight variations with time in culture, and after 1 week of culture between two film layers 67 ± 47 nm fibrils were observed after 1 week. When the film surface was molded into 1 and 2 μm microgrooves, the initial average fibril diameter of the extracellular matrix was 73 ± 21 and 73 ± 31 nm respectively. When cultured on a collagen sponge, an average fibril diameter of 107 ± 20 nm was initially observed and decreased to 47.5 ± 17 nm after 1 week in culture. For cells cultured on a collagen sponge, Western blotting showed an increase in myofibroblast phenotype expression with time in culture. Shifts in phenotype were less distinct for cells cultured on collagen films. The microstructure, rather than geometry, of the matrix substrate appeared to influence the newly synthesized extracellular matrix and cell phenotype.     

Two-dimensional genome-scan identifies novel epistatic loci for essential hypertension

It is well established that gene interactions influence common human diseases, but to date linkage studies have been constrained to searching for single genes across the genome. We applied a novel approach to uncover significant gene-gene interactions in a systematic two-dimensional (2D) genome-scan of essential hypertension. The study cohort comprised 2076 affected sib-pairs and 66 affected half-sib-pairs of the British Genetics of HyperTension study. Extensive simulations were used to establish significance thresholds in the context of 2D genome-scans. Our analyses found significant and suggestive evidence for loci on chromosomes 5, 9, 11, 15, 16 and 19, which influence hypertension when gene-gene interactions are taken into account (5q13.1 and 11q22.1, two-locus lod score=5.72; 5q13.1 and 19q12, two-locus lod score=5.35; 9q22.3 and 15q12, two-locus lod score=4.80; 16p12.3 and 16q23.1, two-locus lod score=4.50). For each significant and suggestive pairwise interaction, the two-locus genetic model that best fitted the data was determined. Regions that were not detected using single-locus linkage analysis were identified in the 2D scan as contributing significant epistatic effects. This approach has discovered novel loci for hypertension and offers a unique potential to use existing data to uncover novel regions involved in complex human diseases.     

Establishment of an in vitro assay to measure the invasion of ovarian carcinoma cells through mesothelial cell monolayers

Ovarian carcinoma is the leading cause of gynecological cancer deaths in the United States. Secondary tumor growths form by tumor cell invasion through the mesothelial lining of the peritoneal cavity and peritoneal organs. To study this interaction, we developed a dye-based in vitro model system in which mesothelial cells were grown as confluent monolayers, permeabilized, and then co-cultured with ovarian carcinoma cells for up to seven days. The mesothelial cells were then stained with trypan blue dye, which enabled the visualization of ovarian carcinoma cell invasion through the monolayers of mesothelial cells. Ovarian carcinoma cell invasion was inhibited for up to 7 days by the addition of GRGDSP peptides, a blocking monoclonal antibody against the β1 integrin subunit, or blocking monoclonal antibodies against matrix metalloproteinases 2 and 9. Cell invasion was also inhibited by hyaluronan and GM6001, a chemical inhibitor of matrix metalloproteinases. Differential gene expression of matrix metalloproteinases, tissue inhibitors of matrix metalloproteinases, and disintegrins were observed in primary ovarian carcinoma tumors and secondary metastases, compared to normal ovaries. Taken together, these results suggest that complex interactions between integrins, disintegrins, matrix metalloproteinases, and tissue inhibitors of matrix metalloproteinases may mediate ovarian carcinoma cell invasion, and that the dye-based assay described herein is a suitable model system for its study. This revised version was published online in July 2006 with corrections to the Cover Date.