Effects of various fatty acids alone or combined with vitamin E on cell growth and fibrinogen concentration in the medium of HepG2 cells

Tigecycline Interferes with Fibrinogen Polymerization Independent of Peripheral Interactions with the Coagulation System

Tigecycline offers broad anti-bacterial coverage for critically ill patients with complicated infections. A described but less researched side effect is coagulopathy. The aim of this study was to test whether tigecycline interferes with fibrinogen polymerization by peripheral interactions. To study the effect of unmetabolized tigecycline, plasma of healthy volunteers were spiked with increasing concentrations of tigecycline. In a second experimental leg, immortalized human liver cells (HepG2) were treated with the same concentrations to test an inhibitory effect of hepatic tigecycline metabolites. Using standard coagulation tests, only the activated thromboplastin time in humane plasma was prolonged with increasing concentrations of tigecycline. Visualization of the fibrin network using confocal live microscopy demonstrated a qualitative difference in tigecycline treated experiments. Thrombelastometry and standard coagulation tests did not indicate an impairment of coagulation. Although the discrepancy between functional and immunologic fibrinogen levels increased in cell culture assays with tigecycline concentration, fibrinogen levels in spiked plasma samples did not show significant differences determined by functional versus immunologic methods. In our in vitro study, we excluded a direct effect of tigecycline in increasing concentrations on blood coagulation in healthy adults. Furthermore, we demonstrated a rapid loss of mitochondrial activity in hepatic cells with supra-therapeutic tigecycline dosages.

Formation of highly reactive cyclopentenone isoprostane compounds (A3/J3-isoprostanes) in vivo from eicosapentaenoic acid

Omega-3 (omega-3) polyunsaturated fatty acids (PUFAs) found in marine fish oils are known to suppress inflammation associated with a wide variety of diseases. Eicosapentaenoic acid (EPA) is one of the most abundant omega-3 fatty acids in fish oil, but the mechanism(s) by which EPA exerts its beneficial effects is unknown. Recent studies, however, have demonstrated that oxidized EPA, rather than native EPA, possesses anti-atherosclerotic, anti-inflammatory, and anti-proliferative effects. Very few studies to date have investigated which EPA oxidation products are responsible for this bioactivity. Our research group has previously reported that anti-inflammatory prostaglandin A(2)-like and prostaglandin J(2)-like compounds, termed A(2)/J(2)-isoprostanes (IsoPs), are produced in vivo by the free radical-catalyzed peroxidation of arachidonic acid and represent one of the major products resulting from the oxidation of this PUFA. Based on these observations, we questioned whether cyclopentenone-IsoP compounds are formed from the oxidation of EPA in vivo. Herein, we report the formation of cyclopentenone-IsoP molecules, termed A(3)/J(3)-IsoPs, formed in abundance in vitro and in vivo from EPA peroxidation. Chemical approaches coupled with gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/mass spectrometry (LC/MS) were used to structurally characterize these compounds as A(3)/J(3)-IsoPs. We found that levels of these molecules increase approximately 200-fold with oxidation of EPA in vitro from a basal level of 0.8 +/- 0.4 ng/mg EPA to 196 +/- 23 ng/mg EPA after 36 h. We also detected these compounds in significant amounts in fresh liver tissue from EPA-fed rats at basal levels of 19 +/- 2 ng/g tissue. Amounts increased to 102 +/- 15 ng/g tissue in vivo in settings of oxidative stress. These studies have, for the first time, definitively characterized novel, highly reactive A/J-ring IsoP compounds that form in abundance from the oxidation of EPA in vivo.

Diet and haemostatic processes

Diet plays an important role in the primary and secondary prevention of cardiovascular disease. The growing perception that abnormal haemostatic processes of coagulation, platelet aggregation and fibrinolysis contribute to cardiovascular disease aetiology motivated this review on the relationships of diet, specific foods and nutrients with haemostatic function. Functional endpoints that reflect the function and status of some of these processes and which can be measured in dietary trials are identified. The effects of energy intake and expenditure, alcohol, total fat and specific fatty acids, non-starch polysaccharides (dietary fibre), antioxidant nutrients and some foods on a variety of haemostatic markers are reviewed. The results indicate that the prudent low-fat, high-fibre diet and maintenance of ideal body weight recommended to protect against and treat hyperlipidaemia and coronary heart disease will also benefit haemostatic profiles. It is concluded that more research on specific effects is needed for improved recommendations on a population level for prevention of cardiovascular disease.

Formation of F-ring isoprostane-like compounds (F3-isoprostanes) in vivo from eicosapentaenoic acid

Eicosapentaenoic acid (EPA, C20:5, omega-3) is the most abundant polyunsaturated fatty acid (PUFA) in fish oil. Recent studies suggest that the beneficial effects of fish oil are due, in part, to the generation of various free radical-generated non-enzymatic bioactive oxidation products from omega-3 PUFAs, although the specific molecular species responsible for these effects have not been identified. Our research group has previously reported that pro-inflammatory prostaglandin F2-like compounds, termed F2-isoprostanes (IsoPs), are produced in vivo by the free radical-catalyzed peroxidation of arachidonic acid and represent one of the major products resulting from the oxidation of this PUFA. Based on these observations, we questioned whether F2-IsoP-like compounds (F3-IsoPs) are formed from the oxidation of EPA in vivo. Oxidation of EPA in vitro yielded a series of compounds that were structurally established to be F3-IsoPs using a number of chemical and mass spectrometric approaches. The amounts formed were extremely large (up to 8.7 + 1.0 microg/mg EPA) and greater than levels of F2-IsoPs generated from arachidonic acid. We then examined the formation of F3-IsoPs in vivo in mice. Levels of F3-IsoPs in tissues such as heart are virtually undetectable at baseline, but supplementation of animals with EPA markedly increases quantities up to 27.4 + 5.6 ng/g of heart. Interestingly, EPA supplementation also markedly reduced levels of pro-inflammatory arachidonate-derived F2-IsoPs by up to 64% (p < 0.05). Our studies provide the first evidence that identify F3-IsoPs as novel oxidation products of EPA that are generated in vivo. Further understanding of the biological consequences of F3-IsoP formation may provide valuable insights into the cardioprotective mechanism of EPA.

Relationship between lipid peroxidation and plasma fibrinogen in middle-aged men

The relationship between lipid peroxidation (plasma malondialdehyde [MDA] concentration) and plasma fibrinogen level was analyzed in 144 men, aged 53-62 years. MDA was measured colorimetrically and fibrinogen with the thrombin method. Mean plasma MDA concentration was 12.6 (SD 1.2) micromol/L, plasma fibrinogen level 2.91 (0.47) g/L, and body mass index 27.1 (3.5) kg/m(2). Prevalence of smoking was 17%. MDA correlated moderately with fibrinogen. Both MDA and fibrinogen correlated positively with waist hip ratio (WHR) and blood leukocyte count, but inversely with VO(2)max. Both MDA and fibrinogen levels were higher in smokers than in non-smokers (p<0. 01). In multiple stepwise regression analysis, plasma MDA, VO(2)max, smoking, and leukocyte count explained 38.1% of the variance in plasma fibrinogen level, with the individual contributions reaching 20.6%, 9.7%, 5.5%, and 2.3%, respectively. WHR, serum triglycerides, and age did not enter the model. These data suggest that increased lipid peroxidation is associated with elevated plasma fibrinogen level in middle-aged men.

Diet and haemostasis: time for nutrition science to get more involved

Abnormal haemostasis, and specifically a pre-thrombotic state characterized by hypercoagulability, increased platelet aggregation and impaired fibrinolysis, is associated with increased atheroma and thrombosis. The recent literature clearly indicates that diet may prevent or be used to treat some abnormal haemostatic states. There are reports on effects of energy intake and expenditure, alcohol consumption, intakes of total fat, different fatty acids, fish oil, NSP and vitamins on markers of coagulation, platelet function and fibrinolysis. Some of the confusion and controversy in this field has arisen because the wrong markers of haemostasis have been measured in dietary trials. Moreover, many of the studies have lacked good dietary control. It is suggested that more sensitive, functional markers of the balance between the different facets of the haemostatic system should be measured. It is also important to test hypotheses developed from known observations and to propose mechanisms of action of the various dietary factors, based on our improved understanding of the haemostatic system.