Docosahexaenoic acid is a strong inhibitor of prostaglandin but not leukotriene biosynthesis.

Docosahexaenoic acid (DCHA), a major polyunsaturated acid component of fish lipid, is not a substrate for prostaglandin synthetase from ram seminal vesicles but is a strong competitive inhibitor (Ki, 0.36 microM) of the conversion by this enzyme of arachidonate (Km, 5.9 microM) to prostaglandins. In contrast, DCHA exhibits little interference to the conversion of arachidonate to metabolites on the leukotriene pathway. DCHA is a very poor substrate for the leukotriene-synthesizing system from RBL-1 cells and no formation of the C22 analog of leukotriene B could be detected from it. The C22 analog of leukotriene C4 was produced by chemical synthesis from DCHA and found to be less than 1/10,000th as active as leukotriene C4 in contracting guinea pig ileum. The DCHA used in this work was obtained in greater than 99.8% purity by a practical process developed for its separation from fish lipid. The cardiovascular protective effects ascribed to dietary intake of fish lipid by certain populations may be due in part to the biological action of DCHA, including the inhibition of prostaglandin biosynthesis.     

Gastric juice ascorbic acid is related to Helicobacter pylori infection but not ethnicity

BACKGROUND: Maori and Pacific Island ethnic groups in New Zealand have a high risk for gastric cancer. Low levels of gastric juice ascorbic acid (vitamin C) have been suggested to be a risk factor for gastric cancer. Previous studies have shown that gastric juice ascorbic acid may be independently associated with both ethnicity and Helicobacter pylori infection. This study aimed to examine the interrelationship between H. pylori and ethnicity in New Zealand. METHODS: Gastric juice was collected into 70% perchloric acid preservative and stored at -80 degrees C. Ascorbic acid was analysed by high-performance liquid chromatography using ion-pair chromatography and electrochemical detection. Inflammation and atrophy was graded from biopsies from multiple sites in the antrum and body. Gastric juice was collected from 89 patients during routine endoscopy. RESULTS: There was a wide range of measured gastric juice ascorbic acid from 0.001 to 410 microg/mL. The median concentration of ascorbic acid for H. pylori-negative patients was 1.78 microg/mL (n = 57) and 0.12 microg/mL (n = 32) for H. pylori-positive patients (P = 0.001). Gastric juice ascorbic acid concentration was not associated with age, endoscopic diagnosis or intestinal metaplasia, but was significantly associated with the degree of acute inflammation (P = 0.01) and the presence of atrophy (P = 0.04).The median ascorbic acid concentration for European patients was 0.92 microg/mL (n = 44) and 0.09 microg/mL (n = 38) for Maori and Pacific Island ethnic groups combined (P = 0.1). Multiple step-wise regression analysis showed that only H. pylori infection was a significant factor for predicting ascorbic acid concentrations (r2 = 0.12). CONCLUSIONS: This study has confirmed that gastric juice ascorbic acid concentration is lower in the presence of H. pylori infection.     

Ankle brachial pressure index but not brachial-ankle pulse wave velocity is a strong predictor of systemic atherosclerotic morbidity and mortality in patients on maintenance hemodialysis

Background

Ankle brachial pressure index (ABPI) and pulse wave velocity (PWV) have been widely recognized as a marker of systemic atherosclerosis. We examined whether ABPI and brachial-ankle PWV (baPWV) predict individual cardiovascular events in patients on maintenance hemodialysis (HD).

Methods

We prospectively followed-up 445 HD patients undergoing both ABPI and baPWV measurements for up to 5 years. They were divided into 2 groups [group with ABPI >0.9 to ≤1.3 (n = 328) and group with ABPI ≤0.9 or >1.3 (n = 117)] and were also divided into tertiles according to the baPWV level (T1: <1850 cm/s; T2: 1850–2310 cm/s and T3: ≥2310 cm/s).

Results

During the follow-up period (mean 43 ± 17 months), 206 cardiovascular events [cardiac event: 125 (28.1%), cerebrovascular events: 39 (8.8%), and peripheral arterial events: 42 (9.4%)] occurred, and 36 (8.1%) and 42 (9.4%) patients experienced cardiovascular and non-cardiovascular deaths, respectively. Cox multivariable analysis showed that presence of ABPI ≤0.9 or >1.3 was a significant predictor of cardiac events [hazard ratio (HR) 1.78, 95% confidential interval (CI) 1.27–2.49, p = 0.0008], cerebrovascular event (HR 1.95, 95%CI 1.13–3.36, p = 0.017), peripheral arterial event (HR 3.64, 95%CI 2.10–6.29, p < 0.0001), composite endpoint of cardiovascular events (HR 2.22, 95%CI 1.64–2.99, p < 0.0001), cardiovascular mortality (HR 2.42, 95%CI 1.44–4.06, p = 0.0008) and all-cause mortality (HR 1.52, 95%CI 1.03–2.25, p = 0.037). However, baPWV did not predict cardiovascular events on multivariate analysis.

Conclusion

ABPI but not baPWV is useful for risk stratification of systemic atherosclerotic morbidity and mortality in HD patients. Furthermore, ABPI could predict not only individual peripheral arterial events but also cardiac and cerebrovascular events.