Biomedical subjects

John F Robinson

Publications and source records attributed to John F Robinson.

4 recordsLinked to original sources

PubMed2005

Quality assessment of microarray experiments.

OBJECTIVES: We describe a quality assurance procedure to maximize the value of oligonucleotide microarray expression profiles. DESIGN, METHODS, AND RESULTS: Background microarray noise was 82.2+/-54.5 and 51.8+/-12.4 units, respectively, before and after enacting the program (P<0.0001). We also noted improved concordance of microarray expression fold-changes for selected genes with results of RT-PCR validation. CONCLUSIONS: This multi-step procedure, including quantification of RNA sample degradation and detection of outlier data points, has increased data quality from our microarray facility.

Animals↗

PubMed2005

ABC transporters and sterol absorption.

Recent molecular studies, in particular investigations of subjects with monogenic disorders of lipoprotein metabolism and studies of induced-mutant mice, have increased the understanding of intestinal sterol absorption. Some of these genes encode adenosine triphosphate [ATP] binding cassette (ABC) transporters that transport dietary cholesterol from enterocytes back out to the intestinal lumen, thereby limiting the amount of cholesterol absorbed. ABC transporters also provide an effective barrier against the absorption of plant sterols, which are normally not absorbed in significant quantities by humans. This mechanism was clarified by the discovery that defects in two adjacent genes encoding ABC transporters are the molecular basis of sitosterolemia, a rare autosomal recessive disease in which plant sterols are absorbed due to failure of intestinal barrier to their absorption. Furthermore, recent experiments performed in induced-mutant mice have solidified the importance of these transporters in intestinal sterol absorption. Together with new developments in the biology of bile acids, sterol absorption is providing interesting directions for metabolism research. In addition to elucidating some of the molecular mechanisms of sterol absorption, these recent findings may lead to new therapeutic options to treat hypercholesterolemia and to help patients at risk of vascular disease reach ever-more stringent target levels.

ATP-Binding Cassette Transporters↗

PubMed2004

Optimizing RNA extraction yield from whole blood for microarray gene expression analysis.

OBJECTIVES: Microarray analysis of gene expression profiles of blood leukocytes has many potential clinical and research applications. DESIGN AND METHODS: We used the PAXgene Blood RNA System to prepare RNA from the whole blood of normal volunteers using two incubation times followed by gene expression profiling using the Affymetrix HU133A GeneChip. CONCLUSIONS: Longer incubation gave a significantly higher RNA yield and samples that were satisfactory for microarray analysis, with excellent pairwise correlations between replicates.

Gene Expression Profiling↗

PubMed2004

Spectrum of HNF1A and GCK mutations in Canadian families with maturity-onset diabetes of the young (MODY).

PURPOSE: Maturity-onset diabetes of the young (MODY) is a subtype of type 2 diabetes characterized by autosomal-dominant inheritance and early onset. The pathophysiology of MODY is primarily defective insulin secretion resulting from mutations in at least 6 different genes. Most affected patients harbour mutations in either GCK (encoding glucokinase, also called MODY2) and HNF1A (encoding hepatic nuclear factor-1alpha, also called MODY3). We studied Canadian probands to determine if they had mutations in MODY2 or MODY3 genes. METHOD: We used genomic DNA sequencing of probands from 9 previously unreported Canadian MODY families. RESULTS: Five MODY probands had mutations in HNF1A, of which 4 were novel (namely IVS5-1delTAG, E275fsdelGAAG, F268S and L44fsdelC) and 4 had mutations in GCK, of which 2 were novel (E237K and L324P). These mutations expand the spectrum of MODY mutations and bring the total number of Canadian MODY families that have been molecularly defined in our laboratory to 15 (8 MODY3 and 7 MODY2). CONCLUSION: Because of the growing evidence that molecular diagnosis may affect prognosis and treatment, this information may be important in future for Canadian MODY families and their physicians.

Adolescent↗