Coronary artery bypass graft surgery up-regulates genes involved in platelet aggregation.

BACKGROUND: During and shortly after coronary artery bypass graft (CABG) surgery, there is an increase in thromboembolic events. CABG, a strong inflammatory stimulus, is associated with a hypercoaguable state. Platelets might contribute to this hypercoaguable state because they have a pivotal role in thrombosis. In the days following surgery there is augmented platelet regeneration in response to the inflammatory stimulus. OBJECTIVES: The aim of this study was to investigate any changes in platelet mRNA profiles to test the hypothesis that post-CABG surgery platelets are associated with a prothrombotic state. METHODS: Blood was sampled and platelets purified from 11 patients before and 3-6 days after CABG. Gene expression profiling was performed using low density array (LDA) plates for seven of the patients. RESULTS: Forty-five genes were examined and those significantly up-regulated were glycoprotein (GP)IIb, GPIIIa and cyclooxygenase-1 (COX-1). These findings were confirmed in four more patients, including flow cytometry analysis of the GPIIb/IIIa receptor. CONCLUSIONS: CABG surgery up-regulates mRNA and protein levels of proteins that are key players in platelet aggregation. Marked elevation of GPIIb/IIIa mRNA levels results in significantly increased GPIIb/IIIa expression in platelets post-CABG surgery, which may be a reason for increased thrombus formation and myocardial infarction after CABG.

Use of the whole leucocyte population in the study of the NFκB pathway.

The nuclear factor NF-{kappa}B (NFκB) is involved in the regulation of innate immunity and in particular, inflammatory genes. It is associated with the pathogenesis of many chronic diseases such as coronary heart disease (CHD). It is believed that individual susceptibility to CHD might be affected by differences in gene transcription and therefore gene expression in circulating cell populations such as leucocytes is of interest. The aim of this study was to investigate whether the total white blood cell population (leucocytes) could be used to study the effect of lipopolysaccharide (LPS) treatment on the expression of genes of the NFκB pathway. Gene expression of the NFκB pathway was examined in total leucocyte, monocyte and neutrophil populations. The majority of the 84 genes examined were up-regulated after treatment with LPS for 12 h in all cell populations examined. The total leucocyte population behaved in a similar manner to both neutrophils and monocytic cells, indicating that it alone could be used in studies, therefore avoiding cell separation, which is time-consuming and can result in cell activation. Furthermore, in clinical studies, it enables a larger number of patient samples to be studied simultaneously, while also reducing the amount of blood required from each. This will provide enough starting material for use with molecular techniques, such as chromatin immunoprecipitation (ChIP) and ChIP-sequencing, and allow large-scale gene expression studies of the NFκB pathway in patients with chronic and acute inflammation with established CHD.

Implications of seasonal priming and reproductive activity on the interpretation of Comet assay data derived from the clam, Tapes semidecussatus Reeves 1864, exposed to contaminated sediments.

We explore the use of the clam Tapes semidecussatus Reeves 1864 as an indicator for the presence of potentially genotoxic substances in estuarine sediments. The limitations associated with the interpretation of Comet assay data (expressed as % DNA in tail) in terms of clam reproductive state, size (age) and thermal exposure history following laboratory acclimation are discussed. Hatchery-reared clams, subjected to ambient temperature fluctuations during growth, were exposed in vivo under laboratory conditions for three weeks to sediment samples collected from a polluted site and a "clean" reference site. The DNA damage observed in haemocytes, gill and digestive gland cells was significantly higher in animals exposed to contaminated sediment compared to those exposed to sediment from the reference site. The extent of DNA damage recorded was not correlated with size (age). Spawning was not observed during the experiment. Nevertheless, clams with well-developed gonads showed a statistically higher degree of DNA damage in gill and digestive gland cells- but not haemocytes, demonstrating an increased sensitivity to potential genotoxic compounds, possibly caused by impaired DNA repair capacity due to reproductive activity. Furthermore, the degree of DNA damage in clams exposed to contaminated sediments was higher in autumn and winter compared to spring and summer, suggesting an effect of seasonal priming.

Detecting genotoxicity using the Comet assay following chronic exposure of Manila clam Tapes semidecussatus to polluted estuarine sediments.

Sediments frequently cause damage to biota due to the accumulation of toxic compounds and the bioavailability of sediment-bound contaminants. Damage can be assessed using biomarkers, such as the degree of genotoxic impact following in vivo exposure to pollutants. Genotoxic damage, expressed as single-strand DNA breaks, was measured in cells isolated from haemolymph, gill and digestive gland from the clam Tapes semidecussatus, using the single cell gel electrophoresis (Comet assay). Clams were exposed for three weeks to sediment samples collected from a polluted site and a 'clean' reference site. The level of DNA damage was assessed using an image analysis package and expressed as Tail Moment. Throughout the study, significant differences in DNA damage were recorded for each tissue type between clams exposed to the two sediment samples. We conclude that the Comet assay is a useful tool for the detection of DNA damage in clams chronically exposed to polluted sediments.