Vascular prostacyclin is increased in patients ingesting omega-3 polyunsaturated fatty acids before coronary artery bypass graft surgery

Use of Intravenous Soybean and Fish Oil Emulsions in Pediatric Intestinal Failure-Associated Liver Disease: A Multicenter Integrated Analysis Report on Extrahepatic Adverse Events

OBJECTIVE

To compare extrahepatic adverse events during fish oil lipid emulsion (FOLE) or soybean oil lipid emulsion (SOLE) treatment in children with intestinal failure-associated liver disease (IFALD).

STUDY DESIGN

In this multicenter integrated analysis, bleeding, bronchopulmonary dysplasia (BPD), retinopathy of prematurity (ROP), infections, and signs of lipid emulsion intolerance were compared between FOLE recipients (1 g/kg/d) (n = 189) and historical controls who received SOLE (≤3 g/kg/d) (n = 73).

RESULTS

When compared with SOLE recipients, FOLE recipients had a lower gestational age (30.5 vs 33.0 weeks; P = .0350) and higher baseline direct bilirubin (DB) (5.8 vs 3.0 mg/dL; P < .0001). FOLE recipients had a decreased incidence of bleeding (P < .0001), BPD (P < .001), ROP (P < .0156), bacterial and fungal infections (P < .0001), and lipid intolerance signs (P < .02 for all). Patients with bleeding vs patients without bleeding had higher baseline DB; the ORs for baseline DB (by mg/dL) and treatment (FOLE vs SOLE) were 1.20 (95% CI: 1.10, 1.31; P ≤ .0001) and 0.22 (95% CI: 0.11, 0.46; P ≤ .0001), respectively. In preterm infants, a higher BPD (P < .0001) and ROP incidence (P = .0071) was observed in SOLE recipients vs FOLE recipients.

CONCLUSIONS

Children with IFALD who received FOLE had fewer extrahepatic adverse events, including a decreased incidence of bleeding, preterm comorbidities, and lipid intolerance signs compared with children with IFALD who received SOLE. TRIAL REGISTRATION CLINICALTRIALS.GOV: NCT00910104 and NCT00738101.

Effect of essential fatty acid blend on circadian variations of ambulatory blood pressure in patients with essential hypertension and coronary artery disease risk markers

Flaxseed oil is an excellent source of alpha-linolenic acid ALA known for its antihypertensive action. Flaxseed oil is unstable and its dose is not achievable in our conventional diet hence blending of natural flaxseed oil with palm oil, containing high flavonoids may be a better strategy, to stabilize the blend and provide proper balance of essential fatty acids and potential antioxidant effects. Aim of this study was to access the effect of blended flaxseed oil on 24 h 7-day circadian variations of blood pressure in subjects with essential hypertension. Assessment of CHAT (circadian hyper amplitude tension) using ABPM is the best marker for cardiovascular function. We registered 50 subjects with CAD (Group 1) and 50 subjects with Essential hypertension HT (Group 2) and 52 control subjects with CAD/Hypertension. Group 1 and 2 participant was supplemented with blended flaxseed oil (BFO) (30 ml/day) for the period of 24 weeks, while control group administered available oils sunflower in identical containers, for a follow-up period of 24 weeks. Twenty four hour seven days continuous ambulatory blood pressure monitoring was done initially and after six months of BFO supplementation. There were significant changes noted in lipid profile along with Ambulatory blood pressure parameters like MESOR, ACROPHASE, Hyperbaric Indexes, and CHAT. Circadian hyper amplitude tension (CHAT) incidence decreased after BFO supplementation. Study results suggest that blended flaxseed oil administration can be a potent natural vegetarian antihypertensive supplement which helps in synchronization of cardiac rhythms, and can be used as a preventive treatment of hypertension and as effective vegetarian source of maintaining Omega 3 and omega 6 ratios of essential fatty acids in the body.

Role of oxylipins generated from dietary PUFAs in the modulation of endothelial cell function

Oxylipins, which are circulating bioactive lipids generated from polyunsaturated fatty acids (PUFAs) by cyclooxygenase, lipooxygenase and cytochrome P450 enzymes, have diverse effects on endothelial cells. Although studies of the effects of oxylipins on endothelial cell function are accumulating, a review that provides a comprehensive compilation of current knowledge and recent advances in the context of vascular homeostasis is lacking. This is the first compilation of the various in vitro, ex vivo and in vivo reports to examine the effects and potential mechanisms of action of oxylipins on endothelial cells. The aggregate data indicate docosahexaenoic acid-derived oxylipins consistently show beneficial effects related to key endothelial cell functions, whereas oxylipins derived from other PUFAs exhibit both positive and negative effects. Furthermore, information is lacking for certain oxylipin classes, such as those derived from α-linolenic acid, which suggests additional studies are required to achieve a full understanding of how oxylipins affect endothelial cells.

Fatty Acid Mediators in the Tumor Microenvironment

Patients with cancer frequently overexpress inflammatory cytokines with an associated neutrophilia both of which may be downregulated by diets with high omega-3 polyunsaturated fatty acids (ω-3 PUFA). The anti-inflammatory activity of dietary ω-3 PUFA has been suggested to have anticancer properties and to improve survival of cancer patients. Currently, the majority of dietary research efforts do not differentiate between obesity and dietary fatty acid consumption as mediators of inflammatory cell expansion and tumor microenvironmental infiltration, initiation, and progression. In this chapter, we discuss the relationships between dietary lipids, inflammation, neoplasia and strategies to regulate these relationships. We posit that dietary composition, notably the ratio of ω-3 vs. ω-6 PUFA, regulates tumor initiation and progression and the frequency and sites of metastasis that, together, impact overall survival (OS). We focus on three broad topics: first, the role of dietary lipids in chronic inflammation and tumor initiation, progression, and regression; second, lipid mediators linking inflammation and cancer; and third, dietary lipid regulation of murine and human tumor initiation, progression, and metastasis.

Modulation of endothelial cell responses and vascular function by dietary fatty acids

Healthy and functional endothelial cells play important roles in maintaining vascular homeostasis, whereas endothelial dysfunction initiates and exacerbates vascular disease progression. Interventional studies with dietary fatty acids have shown that these molecules have varying effects on vascular function. It is hypothesized that the actions of dietary fatty acids on vascular function may be mediated in part through endothelial cells. This review summarizes the results of studies that have examined the acute and chronic effects of dietary fatty acids on endothelial function and vascular properties in humans, as well as the potential mechanisms by which n-3 polyunsaturated fatty acids regulate endothelial function. Altogether, this article provides an extensive review of how fatty acids contribute to vascular function through their ability to modulate endothelial cells and discusses relationships between dietary fatty acids and endothelial cells in the context of vascular dysfunction.

Can Yellow Stripe Scad Compete with Salmon on Its Role in Platelet Phospholipid Membrane and Its Cardiovascular Benefits?

This review article stresses the effective role of dietary fish fillet docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) on overweight as a risk factor of cardiovascular disease (CVD) via platelet phospholipid modification. Several reports have demonstrated that saturated fat in overweight evokes systemic inflammation and more importantly predisposes it to cardiovascular disorder. Prospective studies have shown that saturated fat is directly proportional to the level of arachidonic acids (AA), precursor of thromboxane in the platelet phospholipid membrane as omega-6 fatty acid in overweight and obese people. Some literature has demonstrated that omega-3 fatty acid from fish fillet ameliorates inflammation, reduces proinflammatory cytokine, inhibits signaling pathway, and regulates the physical composition of inflammatory leukocytes and free radicals (ROS). Yellow stripe scad (YSS) is a local Malaysian fish that has been shown to contain a comparable level of EPA/DHA content as observed in salmon. This review article will focus on the dietary role of fish fillet that will balance the omega-6 fatty acid/omega-3 fatty acid ratio in platelet phospholipid from YSS to manage and prevent healthy overweight/obesity-related risk factor of CVD and to avoid the risk orthodox drug treatment.

Fish Oil and Perioperative Bleeding

Background Fish oil is among the most common natural supplements for treatment of hypertriglyceridemia or prevention of cardiovascular disease. However, concerns about theoretical bleeding risk have led to recommendations that patients should stop taking fish oil before surgery or delay in elective procedures for patients taking fish oil by some health care professionals. Methods and Results We tested the effect of fish oil supplementation on perioperative bleeding in a multinational, placebo-controlled trial involving 1516 patients who were randomized to perioperative fish oil (eicosapentaenoic acid+docosahexaenoic acid; 8-10 g for 2-5 days preoperatively, and then 2 g/d postoperatively) or placebo. Primary outcome was major perioperative bleeding as defined by the Bleeding Academic Research Consortium. Secondary outcomes include perioperative bleeding per thrombolysis in myocardial infarction and International Society on Thrombosis and Hemostasis definitions, chest tube output, and total units of blood transfused. Participants' mean (SD) age was 63 (13) years, and planned surgery included coronary artery bypass graft (52%) and valve surgery (50%). The primary outcome occurred in 92 patients (6.1%). Compared with placebo, risk of Bleeding Academic Research Consortium bleeding was not higher in the fish oil group: odds ratio, 0.81; 95% CI, 0.53-1.24; absolute risk difference, 1.1% lower (95% CI, -3.0% to 1.8%). Similar findings were seen for secondary bleeding definitions. The total units of blood transfused were significantly lower in the fish oil group compared with placebo (mean, 1.61 versus 1.92; P<0.001). Evaluating achieved plasma phospholipid omega-3 polyunsaturated fatty acids levels with supplementation (on the morning of surgery), higher levels were associated with lower risk of Bleeding Academic Research Consortium bleeding, with substantially lower risk in the third (odds ratio, 0.30 [95% CI, 0.11-0.78]) and fourth (0.36 [95% CI, 0.15-0.87]) quartiles, compared with the lowest quartile. Conclusions Fish oil supplementation did not increase perioperative bleeding and reduced the number of blood transfusions. Higher achieved n-3-PUFA levels were associated with lower risk of bleeding. These novel findings support the need for reconsideration of current recommendations to stop fish oil or delay procedures before cardiac surgery. Clinical Trial Registration URL: https://www.clinicaltrials.gov . Unique identifier: NCT00970489.

Fish oil LC-PUFAs do not affect blood coagulation parameters and bleeding manifestations: Analysis of 8 clinical studies with selected patient groups on omega-3-enriched medical nutrition

BACKGROUND & AIMS

The increased consumption of fish oil enriched-products exposes a wide diversity of people, including elderly and those with impaired health to relatively high amounts of n-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFAs). There is an ongoing debate around the possible adverse effects of n-3 LC-PUFAs on bleeding risk, particularly relevant in people with a medical history of cardiovascular events or using antithrombotic drugs.

METHODS

This analysis of 8 clinical intervention studies conducted with enteral medical nutrition products containing fish oil as a source of n-3 LC-PUFAs addresses the occurrence of bleeding-related adverse events and effects on key coagulation parameters (Prothrombin Time [PT], (activated) and Partial Thromboplastin Time [(a)PTT]).

RESULTS

In all the patients considered (over 600 subjects treated with the active product in total), with moderate to severe disease, with or without concomitant use of antithrombotic agents, at home or in an Intensive Care Unit (ICU), no evidence of increased risk of bleeding with use of n-3 LC-PUFAs was observed. Furthermore there were no statistically significant changes from baseline in measured coagulation parameters.

CONCLUSION

These findings further support the safe consumption of n-3 LC-PUFAs, even at short-term doses up to 10 g/day of eicosapentaenoic acid + docosahexaenoic acid (EPA + DHA) or consumed for up to 52 weeks above 1.5 g/day, in selected vulnerable and sensitive populations such as subjects with gastrointestinal cancer or patients in an ICU. We found no evidence to support any concern raised with regards to the application of n-3 LC-PUFAs and the potentially increased risk for the occurrence of adverse bleeding manifestations in these selected patient populations consuming fish oil enriched medical nutrition.

The Effects of Immediate Enteral Feeding with a Formula Containing High Levels of ω-3 Fatty Acids in Patients After Surgery for Esophageal Cancer

BACKGROUND

We investigated whether supplementation of enteral nutrition (EN) with omega-3 polyunsaturated acids (PUFAs) affected platelet aggregation, coagulation activity, and inflammatory response in the early stages after esophageal cancer surgery.

METHODS

Twenty-eight patients with esophageal cancer who underwent the same surgical procedure were selected for this study. All patients received EN, which was started immediately after the operation and was increased to a maximum volume of 1500 ml/day by the third postoperative day (POD). Eleven patients received a conventional EN formula (Ensure Liquid), while the remaining 17 patients received a different formula rich in omega-3 PUFAs (Racol [RAC]). Several markers of coagulation and fibrinolysis were determined in POD 2, while the concentrations of interleukin (IL)-6, IL-8, 6-keto-PGF1alpha and thromboxane B2 were determined on PODs 1, 3, and 5.

RESULTS

A total of 27 patients completed the study, 11 in the Ensure Liquid group and 16 in the RAC group. Administration of RAC significantly inhibited the postoperative decrease in platelet count. The level of D-dimer was attenuated significantly in the RAC group. Plasma IL-8 levels were decreased significantly in the RAC group on PODs 1 and 3. The anti-inflammatory effects of omega-3 PUFAs were confirmed by the clinical findings of lower body temperature. The plasma concentration of 6-keto-PFG1alpha also tended to decrease in the RAC group with a significant difference on POD 5.

CONCLUSIONS

Early EN with a large amount of omega-3 PUFAs in reduced platelet aggregation, coagulation activity, and cytokine production. All these effects would be expected to be beneficial in patients following esophageal cancer surgery. The clinical significance of the changes in eicosanoid production remains to be established.

Design of the fish oil inhibition of stenosis in hemodialysis grafts (FISH) study

Background Arteriovenous grafts (AVG) are the predominant form of permanent vascular access used among hemodialysis (HD) patients in North America but suffer from high intervention and complication rates associated with vascular stenosis. The fish oil inhibition of stenosis in hemodialysis grafts (FISH) study evaluates the efficacy of fish oil in improving HD graft patency.

Methods This study is a multi-center, randomized, double blind placebo-controlled clinical trial of 232 chronic HD patients who require a new graft access. Participants are randomized to fish oil versus placebo post-operatively. The primary endpoint is the proportion of AVG with loss of native patency within 12 months of creation. Secondary endpoints are aimed to determine the effect of fish oil on factors that may promote stenosis and thrombosis. Cumulative patency rates, survival analysis, and analysis of inflammatory markers and adverse events will provide a better understanding of the potential effect of fish oil on a patient's vascular access and cardiovascular system. The FISH study is registered at current controlled trials (www.controlled-trials.com) ISRCTN: 15838383.

Results Details of the study protocol are described including mechanisms of reducing bias through randomization and double blinding, sample size determination, evaluation of patient adherence, access monitoring, and the safety of using fish oil. The main challenges of designing and implementing this study, including using a natural supplement as an intervention in modern medical practice and recruitment of graft recipients in the `fistula first' environment are discussed. Conclusion This is the first large, multicenter, randomized controlled trial of a natural supplement in preventing HD graft stenosis and thrombosis. Clinical Trials 2007; 4: 357—367. http://ctj.sagepub.com

Supplementation with omega-3 fish oil has no effect on bone mineral density in adults with knee osteoarthritis: a 2-year randomized controlled trial

This study aimed to determine the effect of fish oil on bone mineral density (BMD). There were no differences in the 2-year BMD measures between high and low dose groups after adjusting for baseline BMD. This randomized controlled trial did not demonstrate any efficacy of omega-3 fatty acids on bone loss in adults.

INTRODUCTION

The purpose of this study is to investigate whether supplementation with high dose omega-3 fish oil could have an impact on BMD.

METHODS

In a multicentre, double-blind randomized controlled trial (RCT) (ACTRN 12607000415404), 202 Australian participants aged ≥40 with knee osteoarthritis (mean age, 61.0 ± 10.0 years; 49 % female) were randomized to receive either high dose (4.5 g eicosapentaenoic acid and docosahexaenoic acid daily) or low dose (0.45 g/day) omega-3 fish oil for 2 years. BMD was assessed at baseline and 2 years by dual energy X-ray absorptiometry.

RESULTS

In subjects with baseline and 2-year assessments, mean standardized BMD at baseline for low or high dose group was 1198 ± 198 and 1157 ± 169 mg/cm(2), respectively, for the lumbar spine and was 1035 ± 165 and 1017 ± 174 mg/cm(2), respectively, for the femoral neck. There were no differences in the 2-year BMD measures between high and low dose groups after adjusting for baseline BMD in the complete case regression analyses (lumbar spine 3.7, 95 % confidence interval (CI) -7.9 to 15.3 mg/cm(2) and femoral neck -5.5, 95 % CI -14.9 to 3.9 mg/cm(2)). The findings did not change with additional adjustments of age, gender, study centre and uses of bone-related drugs during the study period as well as using the intention-to-treat analysis or limiting to older participants (≥55 years at the baseline) (all P ≥ 0.25). Mild adverse events such as headache and gastrointestinal intolerance were common but did not occur more frequently in either group. There were no serious adverse events related to the intervention.

CONCLUSION

A 2-year supplementation with high-dose omega-3 fish oil did not alter bone loss among men and women with knee osteoarthritis.

Safety of docosahexaenoic acid (DHA) administered as DHA ethyl ester in a 9-month toxicity study in dogs

DHA Ethyl Ester (DHA-EE) is a 90% concentrated ethyl ester of docosahexaenoic acid manufactured from the microalgal oil. The objective of the 9-month study was to evaluate safety of DHA-EE administered to beagle dogs at dose levels 150, 1000 and 2000 mg/kg bw/day by oral gavage and to determine reversibility of any findings after a 2-month recovery period. DHA-EE was well tolerated at all doses. There were observations of dry flaky skin with occasional reddened areas at doses ≥1000 mg/kg bw/day. These findings lacked any microscopic correlate and were no longer present after the recovery period. There were no toxicologically relevant findings in body weights, body weight gains, food consumption, ophthalmological examinations, and ECG measurements. Test article-related changes in hematology parameters were limited to decreases in reticulocyte count in the high-dose males and considered non-adverse. In clinical chemistry parameters, dose-related decreases in cholesterol and triglycerides levels were observed at all doses in males and females and attributed to the known lipid-lowering effects of DHA. There were no effects on other clinical chemistry, urinalysis or coagulation parameters. There were no abnormal histopathology findings attributed to test article. The No-Observable-Adverse-Effect Level of DHA-EE was established at 2000 mg/kg bw/day for both genders.

Lower omega-3 index is a marker of increased propensity of hypertensive rat heart to malignant arrhythmias

Polyunsaturated omega-3 fatty acids (omega-3 PUFA) are important components of cell membrane affecting its function and their deficiency is deleterious to health. We have previously shown that spontaneously hypertensive rats (SHR) are prone to life-threatening arrhythmias that are reduced by omega-3 PUFA intake. Purpose of this study was to explore plasma and red blood cells (RBC) profile of omega-3 and omega-6 PUFA as well as to determine omega-3 index, a risk factor for sudden cardiac death, in aged SHR and the effect of omega-3 PUFA intake. Male and female 12-month-old SHR and age-matched Wistar rats fed with omega-3 PUFA (200 mg/kg BW/day/2 month) were compared with untreated rats. Composition of omega-3 PUFA: alpha linolenic acid, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) as well as omega-6 PUFA: linoleic acid and arachidonic acid was analyzed by gas chromatography. Results showed sex- and strain-related differences of basal omega-3 and omega-6 PUFA levels in plasma and RBC as well as in response to omega-3 PUFA intake. Comparing to Wistar rats omega-3 index, expressed as a percentage of EPA+DHA of total fatty acids, was lower in SHR and it increased due to consumption of omega-3 PUFA. Findings support our hypothesis that lower omega-3 index may be also a marker of increased propensity of the hypertensive rat heart to malignant arrhythmias.

Flaxseed oil increases aortic reactivity to phenylephrine through reactive oxygen species and the cyclooxygenase-2 pathway in rats

BACKGROUND

Flaxseed oil has the highest concentration of omega-3 α-linolenic acid, which has been associated with cardiovascular benefit. However, the mechanism underlying the vascular effects induced through flaxseed oil is not well known. Thus, in the present study, we investigated the effects of flaxseed oil on vascular function in isolated rat aortic rings.

METHODS

Wistar rats were treated daily with flaxseed oil or a control (mineral oil) intramuscular (i.m.) for fifteen days. Isolated aortic segments were used to evaluate cyclooxygenase-2 (COX-2) protein expression, superoxide anion levels and vascular reactivity experiments.

RESULTS

Flaxseed oil treatment increased the vasoconstrictor response of aortic rings to phenylephrine. Endothelium removal increased the response to phenylephrine in aortic segments isolated from both groups, but the effect was smaller in the treated group. L-NAME incubation similarly increased the phenylephrine response in segments from both groups. The TXA2 synthase inhibitor furegrelate, the selective COX-2 inhibitor NS 398, the TP receptor antagonist SQ 29.548, the reactive oxygen species (ROS) scavenger apocynin, the superoxide anion scavengers tiron and the phospholipase A2 inhibitor dexamethasone partially reversed the flaxseed oil-induced increase in reactivity to phenylephrine.

CONCLUSIONS

These findings suggest that flaxseed oil treatment increased vascular reactivity to phenylephrine through an increase in ROS production and COX-2-derived TXA2 production. The results obtained in the present study provide new insight into the effects of flaxseed oil treatment (i.m.) on vascular function.

Intake of n-3 Polyunsaturated Fatty Acids Increases Omega-3 Index in Aged Male and Female Spontaneously Hypertensive Rats

The purpose of this study was to examine whether n-3 PUFA intake affects n-3 and n-6 FA levels in plasma and red blood cells as well as omega-3 index in old male and female spontaneously hypertensive (SHR) and healthy rats. Plasma linoleic acid and eicosapentaenoic acid increased due to n-3 PUFA intake in SHR and healthy rats. Comparing to healthy rats the levels of PUFA in red blood cells of SHR were lower in males and higher in females with exception of arachidonic acid, which was high in males and low in females. Feeding of rats with n-3 PUFA resulted in increase of red blood cells levels of eicosapentaenoic acid and/or docosahexaenoic acid in a sex- and strain-dependent manner. Moreover, n-3 PUFA intake decreased arachidonic acid in healthy female rats but increased it in SHR and did not affect it in males. Omega-3 index was lower in SHR comparing to healthy rats and it increased due to the consumption of n-3 PUFA. Results point out sex- and strain-related differences in red blood cells levels of n-3 and n-6 PUFA in basal conditions as well as in response to n-3 PUFA intake.

The effect of omega-3 fatty-acid supplements on perioperative bleeding following posterior spinal arthrodesis

PURPOSE

To investigate the effect of omega-3 fatty-acid supplements (n-3FA) on bleeding during posterior spinal arthrodesis.

METHODS

We reviewed all one- or two-level posterolateral lumbar decompression/fusions with or without interbody fusion by five surgeons within 3 years. Patients taking n-3FA preoperatively were matched 1:2 with controls based on procedure, surgeon and operative time. Patients with abnormal coagulation parameters, known bleeding disorders or other medications that could affect surgical blood loss were excluded.

RESULTS

Twenty-eight patients met inclusion criteria. The n-3FA and control groups were similar with respect to gender, age, body mass index, operative time, and preoperative use of non-steroidal anti-inflammatory drugs. The n-3FAs were stopped an average of 5.2 days before surgery (range 1-10). Mean estimated blood loss (EBL) was 697 ml in the n-3FA group and 771 ml in the control group (p = 0.36). Mean transfused volume of Cell Saver (CS) was 282 ml in the n-3FA group and 321 ml in the control group (p = 0.30). A post hoc power analysis showed that the study was powered to detect a minimum difference of 105 ml for EBL and 50 ml for CS. The multivariate generalized estimating equation did not show a significant difference between groups for EBL or CS (p = 0.35 and p = 0.29, respectively). Secondary outcomes including drop in postoperative hemoglobin, transfusion requirement, complications and surgical drain output were similar between the two groups.

CONCLUSIONS

The n-3FA use did not contribute to higher perioperative blood loss during spinal arthrodesis.

A comparison of the changes in cardiac output and systemic vascular resistance during exercise following high-fat meals containing DHA or EPA

Long-chain n-3 PUFA can lower blood pressure (BP) but their acute effects on cardiac output, BP and systemic vascular resistance (SVR) in response to dynamic exercise are uncertain. We compared the effects of high-fat meals rich in EPA (20 : 5n-3), DHA (22 : 6n-3) or oleic acid (control) on cardiac output, BP and SVR in response to exercise stress testing. High-fat meals (50 g fat) containing high-oleic sunflower oil enriched with 4·7 g of either EPA or DHA v. control (high-oleic sunflower oil only) were fed to twenty-two healthy males using a randomised cross-over design. Resting measurements of cardiac output, heart rate and BP were made before and hourly over 5 h following the meal. A standardised 12 min exercise test was then conducted with further measurements made during and post-exercise. Blood samples were collected at fasting, 5 h postprandially and immediately post-exercise for the analysis of lipid, glucose and 8-isoprostane-F2α (8-iso-PGF2α). Plasma concentrations of EPA and DHA increased by 0·22 mmol/l 5 h following the EPA and DHA meals, respectively, compared with the control (P < 0·001). Resting cardiac output and 8-iso-PGF2α increased similarly following all meals and there were no significant differences in cardiac output during exercise between the meals. SVR was lower at 5 h and during exercise following the DHA but not EPA meal, compared with the control meal, by 4·9 % (95 % CI 1·3, 8·4; P < 0·01). Meals containing DHA appear to differ from EPA with regard to their effects on cardiovascular haemodynamics during exercise.

Plasma n-3 and n-6 fatty acids and the incidence of atrial fibrillation following coronary artery bypass graft surgery

BACKGROUND

The anti-inflammatory or anti-arrhythmic effects of n-3 long-chain polyunsaturated fatty acids (LC-PUFA) may decrease the risk of postoperative atrial fibrillation (POAF), but interventional studies have yielded conflicting results. We examined the association between n-3 LC-PUFA and n-6 LC-PUFA in plasma phospholipids (PL) and POAF in patients undergoing coronary artery bypass grafting (CABG).

METHODS

A total of 125 patients undergoing CABG were enrolled in the study. The levels of fatty acids in PL were measured preoperatively and on the third postoperative day. The endpoint was defined as POAF lasting ≥5 min. The incidence of POAF was compared between quartiles of the level of each fatty acid in plasma PL by univariate and multivariable analysis.

RESULTS

The incidence of POAF was 49·6%. By univariate analysis, the incidence of POAF increased significantly with each higher quartile of pre- and postoperative docosahexaenoic acid (DHA) and diminished significantly with each higher quartile of pre- and postoperative arachidonic acid (AA). For postoperative total n-3 LC-PUFA, there was a significant U-curve relationship where the second quartile had the lowest incidence of POAF or 25·8%. In multivariable analysis, this U-curve relationship between n-3 LC-PUFA levels and POAF risk was not significant, whereas the association between POAF and DHA or AA remained statistically significant.

CONCLUSIONS

This study suggests that n-3 LC-PUFA supplements might prevent POAF in CABG patients with low baseline levels of these fatty acids in plasma PL, but may be harmful in those with high levels. AA may play an important role in electrophysiological processes.

Proresolving lipid mediators: potential for prevention and treatment of periodontitis

AIM

Periodontitis is an inflammatory disease initiated by microbial biofilm. The host response to the biofilm destroys the periodontium mediated by an overly robust inflammatory response in susceptible individuals. Whether the excessive host response is genetic, epigenetic or mediated by environment is unknown. New pathways of resolution of inflammation have been discovered. Resolution of inflammation is an active, agonist-mediated, programmed return to tissue homeostasis.

MATERIALS AND METHODS

Various computer-based search engines were employed to identify papers relevant to resolution of inflammation.

RESULTS

Recent data suggest that chronic inflammatory periodontal disease may be a failure of resolution pathways as well as overexpression of proinflammatory pathways. In this review, the biology of resolution of inflammation will be examined in normal tissues and periodontal disease. Anti-inflammatory pharmacologic agents [non-steroidal anti-inflammatory drugs (NSAIDs)] have been shown to prevent and slow the progression of periodontitis in animals and humans. However, the side effect profile of NSAIDS or other inhibitors or receptor antagonists preclude their use in periodontal therapy.

CONCLUSION

The isolation and characterization of proresolving lipid mediators that are receptor agonists has opened a new area of research for potential therapeutic agents for the management of inflammatory periodontitis.

Statins inhibit cyclooxygenase-2 and matrix metalloproteinase-9 in human endothelial cells: anti-angiogenic actions possibly contributing to plaque stability

AIMS

Cyclooxygenase (COX)-2 expression is increased in inflammation and angiogenesis and also in atherosclerotic plaques, where it co-localizes with metalloproteinases (MMPs) involved in the fibrous cap weakening. Insight into the regulation of COX-2 and MMP-9 expression suggests the involvement of a Rho-dependent pathway. Because statins interfere with Rho activation, we investigated the statin effect on COX-2 and MMP expressions in the human endothelium.

METHODS AND RESULTS

Simvastatin and atorvastatin were incubated with endothelial cells for 12 h before stimulation with phorbol myristate acetate or tumour necrosis factor-alpha, for times suitable to assess the endothelial tube differentiation on Matrigel and COX-2 and MMPs activities, proteins, and mRNA expressions. At 0.1-10 micromol/L, both statins reduced COX-2 expression and activity, without affecting COX-1. The statin effect was reversed by mevalonate and geranylgeranyl-pyrophosphate and mimicked by the Rho inhibitor C3 transferase, indicating the involvement of Rho in the signal transduction pathway leading to COX-2 expression. In parallel, statins, as well as COX-2 inhibitors, reduced the MMP-9 stimulated release and the endothelial tubular differentiation.

CONCLUSION

In the human vascular endothelium, statins reduce COX-2 and MMP-9 expression and activity. Through this mechanism, statins exert an anti-angiogenic effect possibly contributing to the cholesterol-lowering-unrelated protective effects of statins against plaque inflammatory angiogenesis and rupture.

Dietary polyunsaturated fatty acids and age-related membrane changes in the heart

Age-associated modification of cardiac membrane composition and related metabolic processes are major factors underlying the reduced capacity for invoking intrinsic cardioprotective survival mechanisms. In this brief review we examine some of these key membrane lipid modifications, which include alterations in the type and proportion of long-carbon chain polyunsaturated fatty acids (PUFAs). These changes have profound consequences on the efficacy of membrane proteins and lipids involved with numerous processes including ion homeostasis, intracellular signal transduction, free radical metabolism, and mitochondrial energy production. The resultant postoxidative modification of lipids, proteins, and DNA leads to a reduction in capacity for repair and ultimately worsening cellular dysfunction. However, some age-related detrimental adaptations may be counteracted by selectively manipulating membrane lipid and protein composition via dietary treatment with key omega-3 PUFAs. Such pervasive treatment results in manipulation of cellular function at multiple levels from cell membrane to the genome.

n-3 Fatty acids and cardiovascular disease: actions and molecular mechanisms

Cardiovascular disease and atherosclerosis are a leading cause of morbidity and mortality worldwide. Epidemiological studies and randomized control intervention trials have reported that n-3 fatty acids reduce cardiovascular events. A variety of biologic and molecular effects of n-3 fatty acids can modulate the mechanisms of development and progression of atherosclerosis. These include n-3 fatty acid effects on inflammation, cardiac excitability, platelet function, triglyceride blood levels, blood pressure and the stability of atheroma plaques. The molecular mechanisms are still not fully defined; but might involve changes in membrane fluidity, receptor responses and binding to intracellular receptors regulating gene transcription. Understanding and elucidating these mechanisms is important to development of future strategies for prevention and treatment of cardiovascular disease.

Longchain n-3 polyunsaturated fatty acids and microvascular reactivity: Observation in the hamster cheek pouch

Previous experiments in our laboratory, using the hamster cheek pouch microcirculation, have shown that precapillary vessels exhibit spontaneous rhythmic luminal variations, termed vasomotion, a myogenic activity sustained by a balance between membrane currents among which polarizing K(+) currents play an important role. In these microvessels, endothelium-derived relaxing factors (EDRFs) seem to regulate arteriolar diameter [via nitric oxide (NO) and cyclic GMP] and vasomotion [probably via endothelium-derived hyperpolarizing factor (EDHF)]. Fish or fish oil diet can decrease the risk of cardiovascular diseases, probably by modifying the conductance of selective ion channels, such as K(+) and/or Ca(++), and/or increasing the production of vasodilators, such as NO. To investigate its effect on microvascular reactivity, using the same preparation and an intravital microscope coupled to a closed circuit TV system, male hamsters were treated for 14 days, twice a day, with 0.4 mL/100 g body weight with fish or olive oil. An attempt was also undertaken to record in arterioles, in vivo, the membrane potential of smooth muscle cells during their vasomotor activity combining conventional microelectrode and intravital microscopy techniques. The effects of topical application of two vasodilators, acetylcholine [endothelium-dependent one, NO release and membrane hyperpolarization via Ca(++)-activated K(+) channels (K(Ca))] and sodium nitroprusside (endothelium-independent, NO donor and no change on membrane potential) and two vasoconstrictors which elicited membrane depolarization via Ca(++) channels, phenylephrine (alpha(1)-adrenergic receptor agonist) and serotonin (5-hydroxi-tryptamine) on mean internal diameter of arterioles and venules, arteriolar blood flows, spontaneous arteriolar vasomotion frequency and amplitude and functional capillary density (FCD, number of capillaries with flowing red blood cells per unit area of tissue) were determined. Anesthesia was induced by sodium pentobarbital (i.p.) and maintained with alpha-chloralose through the femoral vein. In the presence of vasomotion, the membrane potentials are slowly oscillating by about 20 mV around values of approximately -50 mV in perfect synchrony with vasomotor movements and depolarizing phases coincide with vasoconstrictions while polarizing ones with vasodilatations. Comparing all parameters, in control conditions, only the spontaneous vasomotion frequency was significantly higher (2.37 times higher) on the group treated with fish oil and persisted as such throughout all experiments. With topical application of the drugs mentioned above, the group treated with fish oil showed, for each drug concentration, a balance towards vasodilatation with consequent increase on arteriolar blood flow and on FCD, compared with the olive oil treated one. No significant changes on mean arterial pressure, spontaneous arteriolar vasomotion amplitude or venular diameter could be detected in the two groups. Our results support the concept that, in the hamster cheek pouch microcirculation, fish oil supplementation activates K(+) channels which act as the EDHF and might also increase the production of vasodilators, probably NO.

Subdural hematoma after a fall in an elderly patient taking high-dose omega-3 fatty acids with warfarin and aspirin: case report and review of the literature

The elderly population is at an increased risk for major bleeding, possibly due to increased sensitivity to anticoagulation, multiple comorbidities, and polypharmacy. Elderly patients receiving antiplatelet and anticoagulant therapy have an additional risk for bleeding. Omega-3 fatty acids, also known as fish oil, have been used for hyperlipidemia, coronary heart disease, hypertension, and other conditions. Some studies have demonstrated that consumption of fish oil concentrate, n-3 polyunsaturated fatty acid (n-3 PUFA), results in cardiovascular benefits that include reductions in mortality, sudden death, nonfatal myocardial infarction, and thrombotic stoke, as well as improvement in graft patency. The mechanism of action of n-3 PUFA is not completely understood, but a dual antiplatelet and anticoagulant effect has been proposed. Few data exist on whether or not fish oil can be used safely with other antiplatelet or anticoagulant drugs. We report the case of a patient who after a minor fall developed a subdural hematoma requiring craniotomy that likely was precipitated by concomitant use of high-dose omega-3 fatty acids 6 g/day with both aspirin and warfarin. These findings are important because of the wide availability of omega-3 fatty acids and the propensity for use of complementary and alternative medicine in patients with cardiovascular disease who are already taking antiplatelet and/or anticoagulant agents. Judicious use of these combinations is advised, and pharmacists can play an important role in educating patients and other health care providers about the bleeding risks associated with combination therapy.

Expert opinion: omega-3 fatty acids and bleeding-cause for concern?

Omega-3 fatty acid ethyl esters have well-known triglyceride-lowering properties and were shown >30 years ago to inhibit platelet function. With the recent US Food and Drug Administration (FDA) approval of these agents for treating severe triglyceride elevations, concerns about excess bleeding naturally arise. However, an objective assessment of the evidence for clinically significant bleeding reveals that such concerns are unfounded. As such, the benefits of triglyceride lowering with omega-3 fatty acids more than outweigh any theoretical risks for increased bleeding.

The effect of n-3 PUFA on eNOS activity and expression in Ea hy 926 cells

The aim of this study was to evaluate the effects of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on NO synthase (eNOS) activation in Ea hy 926 endothelial cells. EPA or DHA (0-80 microM), added to the culture medium during 24h, were dose-dependently incorporated into the cells. In control medium, eNOS activity (evaluated by the citrulline assay) and eNOS phosphorylation on Ser 1177 were correlated. They were increased by 10 microM histamine and prevented by 20 microM lysophosphatidylcholine (LPC). By contrast, EPA or DHA increased basal phosphorylation without affecting eNOS activity in non-stimulated cells, but dose-dependently decreased this activity in histamine-stimulated cells without modifying the phosphorylation level. Furthermore, EPA and DHA did not prevent the deleterious effects of LPC on histamine stimulation. In conclusion, incorporation of EPA and DHA could be deleterious for endothelial cells by deregulating the activation of eNOS and preventing NO liberation.

The omega-3 fatty acid docosahexaenoate attenuates endothelial cyclooxygenase-2 induction through both NADP(H) oxidase and PKC epsilon inhibition

A high intake of the omega-3 fatty acid docosahexaenoate [docosahexaenoic acid (DHA)] has been associated with systemic antiinflammatory effects and cardiovascular protection. Cyclooxygenase (COX)-2 is responsible for the overproduction of prostaglandins (PG) at inflammatory sites, and its expression is increased in atheroma. We studied the effects of DHA on COX-2 expression and activity in human saphenous vein endothelial cells challenged with proinflammatory stimuli. A>or=24-h exposure to DHA reduced COX-2 expression and activity induced by IL-1, without affecting COX-1 expression. DHA effect depended on the NF-kappaB-binding site in the COX-2 promoter. EMSAs confirmed that DHA attenuated NF-kappaB activation. Because MAPK, PKC, and NAD(P)H oxidase all participate in IL-1-mediated COX-2 expression, we also tested whether these enzymes were involved in DHA effects. Western blots showed that DHA blocked nuclear p65 NF-kappaB subunit translocation by decreasing cytokine-stimulated reactive oxygen species and ERK1/2 activation by effects on both NAD(P)H oxidase and PKCepsilon activities. Finally, to address the question whether DHA itself or DHA-derived products were responsible for these effects, we inhibited the most important enzymes involved in polyunsaturated fatty acid metabolism, showing that 15-lipoxygenase-1 products mediate part of DHA effects. These studies provide a mechanistic basis for antiinflammatory and possibly plaque-stabilizing effects of DHA.

Omega-3 Fatty Acids and the Regulation of Expression of Endothelial Pro-Atherogenic and Pro-Inflammatory Genes

By partially replacing the corresponding omega-6 analogues in membrane phospholipids, omega-3 fatty acids have been shown to decrease the transcriptional activation of genes--e.g., adhesion molecules, chemoattractants, inflammatory cytokines--involved in endothelial activation in response to inflammatory and pro-atherogenic stimuli. This regulation occurs, at least in part, through a decreased activation of the nuclear factor-kappaB system of transcription factors, secondary to decreased generation of intracellular hydrogen peroxide. Such regulation by omega-3 fatty acids is likely linked to the presence of a higher number of double bonds in the fatty acid chain in omega-3 compared with omega-6 fatty acids. By similar mechanisms, omega-3 fatty acids have been recently shown to reduce gene expression of cyclooxygenase-2, an inflammatory gene involved, through the activation of some metalloproteinases, in plaque angiogenesis and plaque rupture. The quenching of gene expression of pro-inflammatory pro-atherogenic genes by omega-3 fatty acids has consequences on the extent of leukocyte adhesion to vascular endothelium, early atherogenesis and later stages of plaque development and plaque rupture, ultimately yielding a plausible comprehensive explanation for the vasculoprotective effects of these nutrients.

Fish oil before cardiac surgery: neutrophil activation is unaffected but myocardial damage is moderated

Could pre-operative dietary intervention with fish oil reduce neutrophil activation and myocardial damage associated with cardiopulmonary bypass (CPB)? Patients were randomised to receive either 8 g/day fish oil (n=22) or placebo (n=18) for 6 weeks. Neutrophil activation, apoptosis and cardiac damage were measured. Demographics and operative variables were similar. Fish oil diet decreased plasma VLDL from 0.69+/-0.34 to 0.51+/-0.24 mmol/l and triglycerides from 1.68+/-0.70 to 1.39+/-0.54 mmol/l. HDL cholesterol increased from 0.94+/-0.27 to 1.03+/-0.26 mmol/l demonstrating significant treatment effects (P=0.007, 0.02 and 0.0003, respectively) as well as compliance with treatment. There were no significant differences in ex vivo N-formyl-methionyl-leucyl-phenylalanine-stimulated neutrophil superoxide anion generation or myeloperoxidase release at recruitment, pre-operatively and at end-CPB. Apoptosis at end-CPB was equally reduced in both groups from 23+/-9% to 13+/-4% in the fish oil group (P<0.001) and 35+/-14% to 15+/-3% in the placebo group (P=0.001). At end-CPB overall troponin I levels averaged 0.91+/-0.60 ng/ml which clearly exceeded diagnostic levels (0.15 ng/ml). At 24h troponin I fell significantly in the fish oil group to 46+/-23% of end-CPB levels (P=0.0002) whereas it peaked in the placebo group to 107+/-72% (P=0.098 vs. end-CPB); this difference was significant: P=0.013. At 48 h the placebo-treated patients had higher troponins but not significantly so (P=0.059). Area-under-the-curve analysis did not conclusively support this (P=0.068). We conclude that fish oil did not significantly decrease post-CPB neutrophil activation (as detected ex vivo) but may moderate post-operative myocardial damage.

Fish oil consumption and reduction of arterial disease

Fish oil consumption may help to normalize the prethrombotic state and reduce arterial disease. This antithrombotic potential of fish oil, rich in (n-3) polyunsaturated fatty acids (PUFA), has been attributed to a reduction in platelet activation, a lowering of plasma triglycerides and (vitamin K-dependent) coagulation factors and/or a decrease in vascular tone. Most intervention studies have shown only moderate effects of (n-3) PUFA on these hemostatic variables. On the other hand, the usually small prolongation in bleeding time with fish oil does not appear to lead to bruising or hemorrhage, at least in healthy subjects. This contrasts with the increased bleeding risk accompanying the more prominent antihemostatic effects of antiplatelet and anticoagulant drugs. Here we propose that the beneficial effect of (n-3) PUFA diet is related to down-regulation of the mutually positive interactions of platelet activation and coagulation. In addition, we consider the possibility that the dietary effect on hemostatic and lipid factors involves transcription regulation of multiple genes, perhaps in a subject-dependent manner.

The importance of the ratio of omega-6/omega-3 essential fatty acids

Several sources of information suggest that human beings evolved on a diet with a ratio of omega-6 to omega-3 essential fatty acids (EFA) of approximately 1 whereas in Western diets the ratio is 15/1-16.7/1. Western diets are deficient in omega-3 fatty acids, and have excessive amounts of omega-6 fatty acids compared with the diet on which human beings evolved and their genetic patterns were established. Excessive amounts of omega-6 polyunsaturated fatty acids (PUFA) and a very high omega-6/omega-3 ratio, as is found in today's Western diets, promote the pathogenesis of many diseases, including cardiovascular disease, cancer, and inflammatory and autoimmune diseases, whereas increased levels of omega-3 PUFA (a low omega-6/omega-3 ratio) exert suppressive effects. In the secondary prevention of cardiovascular disease, a ratio of 4/1 was associated with a 70% decrease in total mortality. A ratio of 2.5/1 reduced rectal cell proliferation in patients with colorectal cancer, whereas a ratio of 4/1 with the same amount of omega-3 PUFA had no effect. The lower omega-6/omega-3 ratio in women with breast cancer was associated with decreased risk. A ratio of 2-3/1 suppressed inflammation in patients with rheumatoid arthritis, and a ratio of 5/1 had a beneficial effect on patients with asthma, whereas a ratio of 10/1 had adverse consequences. These studies indicate that the optimal ratio may vary with the disease under consideration. This is consistent with the fact that chronic diseases are multigenic and multifactorial. Therefore, it is quite possible that the therapeutic dose of omega-3 fatty acids will depend on the degree of severity of disease resulting from the genetic predisposition. A lower ratio of omega-6/omega-3 fatty acids is more desirable in reducing the risk of many of the chronic diseases of high prevalence in Western societies, as well as in the developing countries, that are being exported to the rest of the world.

Favorable impact of a vegan diet with exercise on hemorheology: implications for control of diabetic neuropathy

A little-noticed clinical report indicates that a low-fat, whole-food vegan diet, coupled with daily walking exercise, leads to rapid remission of neuropathic pain in the majority of type 2 diabetics expressing this complication. Concurrent marked improvements in glycemic control presumably contribute to this benefit, but are unlikely to be solely responsible. Consideration should be given to the possibility that improved blood rheology - decreased blood viscosity and increased blood filterability - plays a prominent role in mediating this effect. There is considerable evidence that neural hypoxia, secondary to impaired endoneurial microcirculatory perfusion, is a crucial etiologic factor in diabetic neuropathy; the unfavorable impact of diabetes on hemorheology would be expected to exacerbate endoneurial ischemia. Conversely, measures which improve blood fluidity would likely have a beneficial impact on diabetic neuropathy. There is indeed evidence that vegan diets, as well as exercise training, tend to decrease the viscosity of both whole blood and plasma; reductions in hematocrit and in fibrinogen may contribute to this effect. The fact that vegan diets decrease the white cell count is suggestive of an improvement in blood filterability as well; filterability improves with exercise training owing to an increase in erythrocyte deformability. Whether these measures influence the activation of leukocytes in diabetics - an important determinant of blood filterability - remains to be determined. There are various reasons for suspecting that a vegan diet can reduce risk for other major complications of diabetes - retinopathy, nephropathy, and macrovascular disease - independent of its tendency to improve glycemic control in type 2 patients. The vegan diet/exercise strategy represents a safe, 'low-tech' approach to managing diabetes that deserves far greater attention from medical researchers and practitioners.

From Inuit to implementation: omega-3 fatty acids come of age

During the past 25 years, the cardiovascular effects of marine omega-3 (omega-3) fatty acids have been the subject of increasing investigation. In the late 1970s, epidemiological studies revealed that Greenland Inuits had substantially reduced rates of acute myocardial infarction compared with Western control subjects. These observations generated more than 4,500 studies to explore this and other effects of omega-3 fatty acids on human metabolism and health. From epidemiology to cell culture and animal studies to randomized controlled trials, the cardioprotective effects of omega-3 fatty acids are becoming recognized. These fatty acids, when incorporated into the diet at levels of about 1 g/d, seem to be able to stabilize myocardial membranes electrically, resulting in reduced susceptibility to ventricular dysrhythmias, thereby reducing the risk of sudden death. The recent GISSI (Gruppo Italiano per lo Studio della Sopravvivenza nell'Infarto miocardico)-Prevention study of 11,324 patients showed a 45% decrease in risk of sudden cardiac death and a 20% reduction in all-cause mortality in the group taking 850 mg/d of omega-3 fatty acids. These fatty acids have potent anti-inflammatory effects and may also be antiatherogenic. Higher doses of omega-3 fatty acids can lower elevated serum triglyceride levels; 3 to 5 g/ d can reduce triglyceride levels by 30% to 50%, minimizing the risk of both coronary heart disease and acute pancreatitis. This review summarizes the emerging evidence of the use of omega-3 fatty acids in the prevention of coronary heart disease.

Cyclo-oxygenase-2: pharmacology, physiology, biochemistry and relevance to NSAID therapy

Cyclo-oxygenase is expressed in cells in two distinct isoforms. Cyclo-oxygenase-1 is present constitutively whilst cyclo-oxygenase-2 is expressed primarily after inflammatory insult. The activity of cyclo-oxygenase-1 and -2 results in the production of a variety of potent biological mediators (the prostaglandins) that regulate homeostatic and disease processes. Inhibitors of cyclo-oxygenase include the nonsteroidal anti-inflammatory drugs (NSAIDs) aspirin, ibuprofen and diclofenac. NSAIDs inhibit cyclo-oxygenase-2 at the site of inflammation, to produce their therapeutic benefits, as well as cyclo-oxygenase-1 in the gastric mucosa, which produces gastric damage. Most recently selective inhibitors of cyclo-oxygenase-2 have been developed and introduced to man for the treatment of arthritis. Moreover, recent epidemiological evidence suggests that cyclo-oxygenase inhibitors may have important therapeutic relevance in the prevention of some cancers or even Alzheimer's disease. This review will discuss how the new advancements in NSAIDs research has led to the development of a new class of NSAIDs that has far reaching implications for the treatment of disease.