Atherogenesis and fibrinogen: historical perspective and current status

Control of fibrinogen biosynthesis: role of the FFA/albumin ratio

The rate of biosynthesis and turnover of the plasma protein fibrinogen is a marker of metabolic signaling in aging and disease. The rate in the young normal human subject of 0.260 mg/ml/24 h increases to 0.378 in older normal subjects and to 0.466 in age matched coronary thrombosis patients measured by endogenous labeling of fibrinogen with l-glutamic acid-C14. The increased rate of fibrinogen turnover has been traced to generation of fibrin by labeling the polymers with glycine C14 ethyl esters in the presence of activated fibrin stabilizing factor. Circulating fibrin increased 520% above normal in ischemic thrombotic cerebrovascular disease. Long chain saturated free fatty acids (FFA) exercise not only primary control over incorporation of Cl4 labeled amino acids into the fibrinogen structure but also activate the cascade sequence of reactions which convert fibrinogen into occlusive fibrin polymers. FFA are normally bound and transported by plasma albumin to mitochondrial sites of energy metabolism. Albumin synthesis declines with aging. This decline is associated with increased plasma levels of FFA resulting in an increase in the plasma FFA/albumin ratio. Correction of this ratio in vitro by restoration of a normal FFA/albumin ratio restores a normal level of fibrinogen synthesis by human hepatocytes.

The negative effects of hydrogenated trans fats and what to do about them

Partially hydrogenated vegetable oils have been in the American diet since 1900. More than 50 years ago they were found to contain trans fatty acids that were different from natural fatty acids in plant oils and in animal fat. There was growing evidence that the consumption of trans fats have negative health effects, including increasing plasma lipid levels. In 2003, the Food and Drug Administration (FDA) ruled that the amount of trans fat in a food item must be stated on the label after January 1, 2006; food items could be labeled 0% trans if they contain less than 0.5g/serving. Since the initial ruling, it is now known that the fatty acids in partially hydrogenated vegetable oil are 14 cis and trans isomers of octadecenoic and octadecadienoic acids that are formed during hydrogenation. They cause inflammation and calcification of arterial cells: known risk factors for coronary heart disease (CHD). They inhibit cyclooxygenase, an enzyme required for the conversion of arachidonic acid to prostacyclin, necessary for the regulation of blood flow. There have been several reformulations of hydrogenated fat containing varying amounts of trans fatty acids and linoleic acid, an essential fatty acid that is converted to arachidonic acid. Epidemiological data suggest that when trans fat percentages go up and linoleic acid percentages go down, death rates rise; when trans goes down, death rates go down. In spite of the harmful effects of trans fats, the FDA allows it in the food supply as long as the amount in a food item is declared on the label. Trans fat should be banned from the food supply.

Cardioprotective effects of curcumin

Curcumin, a major active component of turmeric, is extracted from the powdered dry rhizome of Curcuma longa Linn (Zingiberaceae) and it has been used for centuries in indigenous medicine. We have shown that curcumin has a protective role against myocardial necrosis in rats. The antioxidant activity of curcumin could be attributed to the phenolic and methoxy groups in conjunction with the 1,3-diketone-conjugated diene system, for scavenging of the oxygen radicals. In addition, curcumin is shown to enhance the activities of detoxifying enzymes such as glutathione-S-transferase in vivo. We have also shown that oxygen free radicals exacerbate cardiac damage and curcumin induces cardioprotective effect and it also inhibits free-radical generation in myocardial ischemia in rats. This chapter on the cardioprotective effects of curcumin covers the following aspects: (1) the history of curcumin and its discovery as a potent drug with relevance to cardiovascular diseases; (2) mechanistic role of curcumin in vitro, emphasizing the antiplatelet and anticoagulant effects; (3) cardiovascular properties of curcumin; (4) application of curcumin in different animal models (viz. myocardial ischemia, myocardial infarction, cardiomyopathy, and arrhythmia in vitro and in vivo); (5) curcumin free-radical scavenging activity, particularly against O2 radical and depletion of the oxidative stress.

Increased serum laminin and angiogenin concentrations in patients with peripheral arterial occlusive disease

AIM

To measure serum laminin and angiogenin concentrations in patients with peripheral arterial occlusive disease (PAOD) Fontaine stages IIb, III, and IV.

METHODS

The study population comprised 38 patients (20 men and 18 women) with stage IV PAOD, 11 patients (six men and five women) with stage III PAOD, 18 patients (10 men and eight women) with stage IIb PAOD, and 23 patients (10 men and 13 women) with deep vein thrombosis. Fifteen normal subjects (matched for risk factors) and 10 patients (five men and five women) without PAOD served as controls. Serum samples were obtained at admission and serum laminin and angiogenin concentrations were measured using an enzyme linked immunosorbent assay.

RESULTS

Patients with stage IV PAOD had higher serum laminin (mean +/- SEM; 826 +/- 97 ng/ml) and angiogenin concentrations (467 +/- 26 pg/ml) than normal subjects (laminin: 379 +/- 21 ng/ml; angiogenin: 358 +/- 16 pg/ml) and patients without PAOD (laminin: 277 +/- 34 ng/ml; angiogenin: 406 +/- 25 pg/ml). A significant correlation was found between angiogenin and laminin and between serum laminin and fibrinogen concentrations in patients with stage IV disease.

CONCLUSIONS

Raised laminin and angiogenin concentrations may be indicators of endothelial damage caused by reduced vascular perfusion or compensatory revascularisation, or both.