Biomedical subjects

Dennis O'Kane

Publications and source records attributed to Dennis O'Kane.

4 recordsLinked to original sources

PubMed2003

Microarray and microfluidic methodology for genotyping cytokine gene polymorphisms.

Cytokine genetic polymorphisms are the subject of disease-association studies that require large-scale human genotyping. Polymerase chain reaction based custom microarrays and microfluidics systems were used to develop genotyping assays for following cytokine polymorphisms: tumor necrosis factor-alpha G-308A, interleukin-4 (IL-4) C-589T, interferon-gamma (CA)n repeats, IL-1RN 86-bp variable number of tandem repeats (VNTR), and CCR5 32-bp indel. For G-308A, 70.9% of DNA samples assayed were homozygous for wild type, 25.5% were heterozygous, and none were homozygous for variant allele. For C-589T, 35.5% of DNA samples were homozygous for wild type, 38% were heterozygous, and 22% were homozygous for variant. For IL-1RN VNTR, 71% of DNA samples were homozygous and the remainder were heterozygous. For CCR5, 96.4% of amplicons were homozygous for wild type, and 3.6% were heterozygous containing deletion. For IFN-gamma (CA)n repeats, 35.6% had 2,2 alleles, 42.2% had 2,3 alleles, and 11% had 3,3 alleles with alleles 1 through 5 corresponding to 11 through 15 repeats, respectively. There was good concordance between the results we obtained and current "gold-standard" methodologies for analyzing single nucleotide polymorphisms and size polymorphisms. Electronic DNA concentration with high stringency predisposes microarray technology to hybridization fidelity and accuracy, and microfluidics systems outperform conventional methodologies for size polymorphisms. Comprehensive genotyping can be achieved for clinical epidemiologic studies on cytokine gene polymorphisms using this approach.

Cytokines↗

PubMed2003

Differential HLA gene expression in measles vaccine seropositive and seronegative subjects: a pilot study.

This is the first study using GeneChip technology to elucidate genetic determinants of the measles vaccine response. A comparative gene expression study was conducted using Affymetrix's Human GeneChip U-95A in 5 human subjects immunized with a 'booster' dose of measles vaccine (Attenuax, Merck) to determine whether serologically distinct subjects exhibit differential expression of human leukocyte antigen (HLA) genes. Healthy individuals aged 15-25 y, previously immunized with 2 doses of measles-mumps-rubella-II (MMR-II) vaccine, were classified as measles vaccine immunoglobulin G-specific antibody seronegatives (n = 2) and seropositives (n = 3). Changes in expression of HLA genes in seronegatives and seropositives were studied on days 7 and 14 post-measles vaccination using Microarray Suite 5.0 (MAS 5.0). There was increased expression of the HLA class I-B (p = 0.0002), HLA class II cluster of DMA, DMB, TAP1, TAP2 (p = 0.0007) and HLA-DR (p = 0.0001) genes, and decreased expression of HLA class I MICB molecule (p = 1), HLA class I-A (p = 0.9999) and major histocompatibility complex class III HSP 70 (p = 0.9999) genes on day 7 or day 14 postvaccination in seropositives compared with seronegatives. These results suggest an association between antibody response and differential HLA gene activation and may explain one potential mechanism underlying measles vaccine non-response.

Adolescent↗

PubMed2002

Non-invasive in vivo monitoring of trackable viruses expressing soluble marker peptides.

Noninvasive methods are needed to study the kinetic properties of viruses in living organisms. Oncolytic viruses are used increasingly for cancer therapy but there is currently no satisfactory way to measure efficiency of tumor transduction, changing levels of viral gene expression or the timing of virus elimination. We therefore generated trackable oncolytic measles viruses expressing inert (nonimmunogenic, nonfunctional and accurately measurable) soluble marker peptides. The marker peptides did not compromise virus replication. Ex vivo and in vivo kinetics of the trackable viruses could be easily followed by measuring the concentrations of virally encoded marker peptides in culture supernatant or in serum. When mice bearing human tumor xenografts were challenged with the trackable viruses, distinct kinetic profiles of marker-gene expression could be correlated with distinct therapeutic outcomes. Oncolytic viruses expressing inert soluble marker polypeptides should greatly facilitate the rational development of effective, individually tailored cancer virotherapy.

Animals↗

PubMed2002

N-acetyltransferase 1 and 2 genotypes do not predict response or toxicity to treatment with mesalamine and sulfasalazine in patients with ulcerative colitis.

OBJECTIVES: 5-Aminosalicylate is metabolized in colonic mucosa by N-acetyltransferase 1 (NAT1), and sulfapyridine is metabolized in the liver by N-acetyltransferase 2 (NAT2). Common genetic polymorphisms in these enzymes result in rapid and slow acetylation. We determined the association between NAT1 genotype and response to mesalamine and sulfasalazine, as well as between NAT2 genotype and toxicity to sulfasalazine, in a population-based cohort of patients with ulcerative colitis. METHODS: DNA was obtained from 77 white patients with ulcerative colitis from Olmsted County, MN. NAT1 and NAT2 genotyping was performed using microelectronic array devices. Phenotypes were deduced from previously published genotype/phenotype correlations. Clinical response to mesalamine and sulfasalazine, and toxicity to sulfasalazine, were determined by medical record review and associated with NAT1 and NAT2 genotypes. RESULTS: The clinical response rates among 52 patients treated with mesalamine were 67% (31 of 46) for rapid acetylators and 83% (five of six) for slow acetylators (odds ratio = 0.4, 95% CI = < 0.1-3.9, p = 0.65). Similarly, the clinical response rates among 64 patients treated with sulfasalazine were 74% (43 of 58) for rapid acetylators and 67% (four of six) for slow acetylators (odds ratio = 1.4, 95% CI = 0.2-8.6, p = 0.65). The toxicity rates among the 64 patients treated with sulfasalazine were 34% (12 of 35) for slow acetylators and 45% (13 of 29) for rapid acetylators (odds ratio = 0.6, 95% CI = 0.2-1.8, p = 0.65). CONCLUSIONS: NAT1 and NAT2 genotypes did not predict response to mesalamine or sulfasalazine, or toxicity to sulfasalazine.

Adolescent↗