Biomedical subjects

Andrew B Goulter

Publications and source records attributed to Andrew B Goulter.

5 recordsLinked to original sources

PubMed2006

Evaluation of low density array technology for quantitative parallel measurement of multiple genes in human tissue.

BACKGROUND: Low density arrays (LDAs) have recently been introduced as a novel approach to gene expression profiling. Based on real time quantitative RT-PCR (QRT-PCR), these arrays enable a more focused and sensitive approach to the study of gene expression than gene chips, while offering higher throughput than more established approaches to QRT-PCR. We have now evaluated LDAs as a means of determining the expression of multiple genes simultaneously in human tissues and cells. RESULTS: Comparisons between LDAs reveal low variability, with correlation coefficients close to 1. By performing 2-fold and 10-fold serial dilutions of cDNA samples in the LDAs we determined a clear linear relationship between the gene expression data points over 5 orders of magnitude. We also showed that it is possible to use LDAs to accurately and quantitatively detect 2-fold changes in target copy number as well as measuring genes that are expressed with low and high copy numbers in the range of 1 x 10(2)-1 x 10(6) copies. Furthermore, the data generated by the LDA from a cell based pharmacological study were comparable to data generated by conventional QRT-PCR. CONCLUSION: LDAs represent a valuable new approach for sensitive and quantitative gene expression profiling.

DNA Primers↗

PubMed2005

Effective analysis of genomic data.

High-throughput biotechnology has enabled genome-wide investigation of gene expression and has the potential to identify genes that have a role to play in focal cerebral ischemia, as well as many other interventions. The advent of this technology has also led to the generation of large amounts of expensive and complex expression data. One of the major problems with the generation of so much data is locating and extracting the relevant information to aid target identification and interpretation effectively and reliably. Statistical involvement is vital. Not only does it help to ensure effective extraction of information from the data, it also increases the likelihood that the data collected will embody the information about the differential expression of interest in the first place. The goal of this chapter is to recommend an effective process for investigating gene expression data. There are five stages in this process that we believe lead to reliable results when routinely applied to an expression dataset, once it has been appropriately generated and collected: (1) biological problem definition and design selection; (2) data examination, "preprocessing," and reexamination; (3) data analysis step I: screening for differentially expressed genes; (4) data analysis step II: verifying differential expression; and (5) biological verification, interpretation, and communication.

Computational Biology↗

PubMed2004

ACE2 gene expression is up-regulated in the human failing heart.

BACKGROUND: ACE2 is a novel homologue of angiotensin converting enzyme (ACE). ACE2 is highly expressed in human heart and animal data suggest that ACE2 is an essential regulator of cardiac function in vivo. Since overactivity of the renin-angiotensin system contributes to the progression of heart failure, this investigation assessed changes in gene expression of ACE2, ACE, AT1 receptor and renin in the human failing heart. METHODS: The sensitive technique of quantitative reverse transcriptase polymerase chain reaction was used to determine the level of mRNA expression of ACE and ACE2 in human ventricular myocardium from donors with non-diseased hearts (n = 9), idiopathic dilated cardiomyopathy (IDC, n = 11) and ischemic cardiomyopathy (ICM, n = 12). Following logarithmic transformation of the data, a one-way analysis of variance was performed for each target gene followed by a Dunnett's test to compare the two disease groups IDC and ICM versus control. RESULTS: As anticipated, ACE mRNA was found to be significantly increased in the failing heart with a 3.1 and 2.4-fold up-regulation found in IDC and ICM relative to non-diseased myocardium. Expression of ACE2 mRNA was also significantly up-regulated in IDC (2.4-fold increase) and ICM (1.8-fold increase) versus non-diseased myocardium. No change in angiotensin AT1 receptor mRNA expression was found in failing myocardium and renin mRNA was not detected. CONCLUSIONS: These data suggest that ACE2 is up-regulated in human IDC and ICM and are consistent with the hypothesis that differential regulation of this enzyme may have important functional consequences in heart failure. This strengthens the hypothesis that ACE2 may be a relevant target for the treatment of heart failure and will hopefully spur further studies to clarify the functional effects in human myocardium of ACE2 derived peptides.

Adolescent↗

PubMed2003

Chylomicron-remnant-like particles inhibit the basal nitric oxide pathway in porcine coronary artery and aortic endothelial cells.

The effects of chylomicron remnants on the activity of basally produced nitric oxide (NO) from porcine coronary artery rings and porcine aortic endothelial cells were studied by investigating the effects of chylomicron-remnant-like particles (CMR-LPs) containing porcine apolipoprotein E on the vessel tone of porcine coronary arteries and on cGMP release by aortic endothelial cells. CMR-LPs were oxidized by incubation with CuSO(4) (10 microM) for 18 h at 37 degrees C. N (omega)-nitro-L-arginine (L-NOARG) and oxidized CMR-LPs (oxCMR-LPs), but not native CMR-LPs, increased the vessel tone of static porcine coronary artery rings (increase in tone as a percentage of the tone induced by depolarizing Krebs-Henseleit solution: L-NOARG, 14.24 +/- 2.09; oxCMR-LPs, 4.98 +/- 0.88; and native CMR-LPs, 0.47 +/- 0.21). L-NOARG, endothelium removal and oxCMR-LPs also all significantly increased the maximum relaxation of the vessels to S -nitroso- N -acetyl-DL-penicillamine. In addition, oxCMR-LPs reduced the amounts of cGMP released by porcine aortic endothelial cells into the culture medium from 116 +/- 12.0 to 84.2 +/- 11.6 fmol/microg of cellular protein, mimicking the effects of L-NOARG. These results indicate that oxCMR-LPs, but not native CMR-LPs, inhibit the activity, production or release of NO from unstimulated porcine coronary and aortic endothelial cells. oxCMR-LPs mimicked the addition of L-NOARG and endothelium removal in these experimental systems, suggesting that the lipoproteins were interfering with the L-arginine/NO pathway. This study provides further evidence to support a role of chylomicron remnants in the development of atherosclerosis.

Animals↗

PubMed2002

Chylomicron-remnant-like particles inhibit receptor-mediated endothelium-dependent vasorelaxation in pig coronary arteries.

The influence of native and oxidized chylomicron-remnant-like particles (CMR-LPs) on endothelium-dependent relaxation in pig coronary arteries was studied. Artificial lipid particles of a size and lipid composition resembling chylomicron remnants and containing pig apolipoprotein E were used to investigate the effects of chylomicron remnants on the relaxation of isolated segments of pig coronary arteries in response to three endothelium dilators: 5-hydroxytryptamine (5-HT), bradykinin and the calcium ionophore A23187. CMR-LPs caused significant inhibition of the maximum relaxation response of the vessels to 5-HT, but not that to bradykinin or A23187 ( P <0.05). In contrast, CMR-LPs that had been oxidized by incubation with 10 microM CuSO(4) (oxidized CMR-LPs) were found to significantly reduce maximal relaxation to bradykinin by 13% ( P <0.05) and to reduce the sensitivity of the tissue to A23187 by 1.7-fold ( P <0.05). In experiments in which either the L-arginine/nitric oxide (NO) pathway or the endothelium-derived hyperpolarizing factor (EDHF) pathway was selectively inhibited, leaving the other intact, the inhibitory effect of oxidized CMR-LPs was observed only in vessels in which the -arginine/NO-mediated pathway was operative. Furthermore, the oxidized particles had no inhibitory effect on the relaxation of the vessel segments to the non-endothelium-dependent agonists S -nitro- N -acetylpenicillamine, 5'-( N -ethylcarboxamido)adenosine or pinacidil. These results demonstrate that CMR-LPs inhibit vascular relaxation in pig coronary arteries by an endothelium-dependent mechanism involving the L-arginine/NO pathway, but not the EDHF pathway, and provide evidence in support of a role for chylomicron remnants in the endothelial dysfunction associated with hypercholesterolaemia and atherogenesis.

Animals↗