6-Oxo-PGF1alpha and 8-epi-PGF2alpha in human atherosclerotic vascular tissue.

Isoprostanes are a new family of compounds generated by the free radical catalyzed action on arachidonic acid. Formed during oxidation they have been claimed to be a reliable indicator of in vivo oxidation injury. We assessed the amount of 8-epi-PGF2alpha in human surgical specimens as compared to PGI2 (via its stable metabolite 6-oxo-PGF1alpha), the major compound generated by vascular tissue. 8-epi-PGF2alpha is low in normal vascular tissue as is the 8-epi-PGF2alpha/6-oxo-PGF1alpha ratio. The vessels of smokers in general exhibited an increased 8-epi-PGF2alpha (r=0.82) and a decreased 6-oxo-PGF1alpha (r=0.71). The 8-epi-PGF2alpha/6-oxo-PGF1alpha ratio is, not significantly, increased in vessels derived from hyperlipidemics and hypertensives. These findings indicate that lipid peroxidation occurs within the human arterial wall as evidenced by 8-epi-PGF2alpha, probably further decreasing the synthesis of PGI2 and promoting atherogenic mechanisms.     

LDL-apheresis decreases plasma levels and urinary excretion of 8-epi-PGF2alpha

Isoprostanes (IP) generated during free radical catalyzed oxidation injury have been claimed as a reliable indicator of oxidative stress in vivo. In particular, they are formed during LDL-oxidation. Vascular content, plasma levels and urinary excretion of IP were reported to be elevated in hypercholesterolemia. We therefore assessed the values of the IP 8-epi-PGF2alpha in plasma and urine in nine patients (7 males, 2 females) suffering from severe heterozygous hypercholesterolemia before and after LDL-apheresis as well as during the interval. LDL-apheresis caused a significant (P<0.01) drop in 8-epi-PGF2alpha in plasma and urine. The respective values in smokers (n = 4) were significantly (P<0.01) higher as compared to non-smokers. No sex difference was seen. Together with the findings of a parallel decrease in oxidized LDL, these data show a significant benefit of LDL-apheresis reducing in vivo oxidation injury. This benefit may at least partly contribute to the clinical improvement seen in the patients treated.     

Enhanced accumulation of pericardial fluid adenosine and inosine in patients with coronary artery disease.

Adenosine and inosine are believed to have cardioprotective effects. However, little is known about their possible role in the metabolic autoregulation of human coronaries and in pathologic conditions with supply/demand imbalance of the heart such as coronary artery disease. Since these low molecular weight nucleosides freely diffuse through the monolayer of the visceral pericardium, adenosine and inosine concentrations in pericardial fluid may well reflect the conditions in cardiac interstitium. The pericardial fluid and systemic venous blood adenosine and inosine concentrations were measured in 98 human subjects undergoing heart surgery for coronary artery disease or valvular heart disease. Adenosine and inosine concentrations were measured by HPLC with UV detection. In subjects with coronary artery disease pericardial fluid nucleoside concentrations were significantly higher than in patients with valvular heart disease (adenosine: 1545 (996-3146) nmol/L [median (25th-75th quartiles)] vs. 738 (390-2527) nmol/L, P<0.01; inosine: 658 (321-1331) nmol/L vs. 347 (159-1037) nmol/L, P<0.05), while in both patient groups pericardial fluid nucleoside concentrations were higher by an order of magnitude than in venous plasma. Our results show the enhanced release of adenosine and inosine by the ischemic myocardium as a marker of supply/demand imbalance and support the hypothesis that these cardiac nucleosides may have an important role in the adaptation of coronary blood flow in human coronary artery disease.     

Cigarette smoke concentrate increases 8-epi-PGF2alpha and TGFbeta1 secretion in rat mesangial cells

Epidemiological studies have shown that cigarette smoke, an oxidant agent, is a risk factor for the development of diabetic nephropathy (DN), in which pathogenesis transforming growth factor beta(1) (TGFbeta(1)) plays a key role. In our experimental model we exposed mesangial cell cultures to cigarette smoke concentrate (CSC) to study the effect of smoking on the pathogenesis of DN. Thus, we analyzed the effect of CSC on TGFbeta(1) and lipid peroxidation (8-epi-PGF(2alpha)) in rat mesangial cells. Furthermore, since the protein kinase C (PKC) pathway appears to be a key factor for the enhanced production of TGFbeta(1), we also analyzed the effect of the selective PKCbeta inhibitor LY379196 on TGFbeta(1) response to CSC. CSC induced an increase of both TGFbeta(1) and 8-epi-PGF(2) compared to basal conditions (5 mM glucose). The CSC-induced increase in TGFbeta(1) secretion was significantly suppressed by LY379196. These data suggest that smoking could increase TGFbeta(1) production, probably due to oxidative stress and PKCbeta activation. This finding supports the concept that smoking is a risk factor for DN development.     

In vivo effect of 8-epi-PGF2alpha on retinal circulation in diabetic and non-diabetic rats

Retinal hemodynamic responses to a F2-isoprostane, 8-epi-PGF2alpha, were quantitated in vivo in non-diabetic and diabetic rats using a video fluorescein angiography system. Vascular diameters and retinal mean circulation time were determined before and after 5 microl intra-vitreous injection of 8-epi-PGF2alpha (10(-5) to 10(-3) M), 10(-4) M 8-epi-PGF2alpha, + 10(-3) M SQ29,548 or 10(-3) M LCB2853 (two inhibitors of TXA2 receptor), 10(4) M 9beta-PGF2alpha, or the carrier in non-diabetic animals. Diabetic rats received either 8-epi-PGF2alpha 10(-4) M, or the carrier. Compared to control animals, diabetic rats presented in the basal state a venous vasodilation (P<0.01), without modification of retinal mean circulation time or blood flow. After intravitreous injection of 8-epi-PGF2alpha, a significant arterial vasoconstriction was observed in control but not in diabetic animals. This vasoconstriction was concomitant with increased retinal mean circulation time in control but not in diabetic rats, inducing an impaired reduction of blood flow. No vasoconstriction was observed after injection of either the carrier, 9beta-PGF2alpha or the isoprostane associated to the inhibitors of TXA2 receptors. This is the first direct observation that the isoprostane 8-iso-PGF2alpha is a potent vasoconstricting agent in the retina. It occurs at the arterial but not venous level, and is likely mediated through a TXA2-like receptor. Differences observed between control and diabetic animals suggest altered adaptative mechanisms toward vasoconstrictor substances (such as isoprostanes) in diabetic rats.     

Low density lipoproteins isolated from the blood of patients with ischemic heart disease induce accumulation of lipids in human aortic intima cells

Very low density lipoproteins (VLDL), low density lipoproteins (LDL) and high density lipoproteins (HDL) were isolated from the blood of healthy subjects and CHD patients. LDL from the blood of healthy individuals did not raise the intracellular lipid values within 24 h of cultivation. During intracellular lipid values within 24 h of cultivation. During the same incubation period. LDL obtained from the blood of CHD patients caused a 2- to 5-fold rise in cholesterol esters as well as a 1.5- to 3-fold rise in free cholesterol and triglycerides, while the intracellular phospholipid levels remained unchanged. In one of the three cases, the ability to raise the intracellular level of cholesterol esters was demonstrated by VLDL (500 micrograms/ml) derived from CHD patients blood. HDL did not affect the lipid levels in smooth muscle cells cultured from unaffected intima. The obtained data suggests that circulating LDL and, possibly, VLDL in the blood of CHD patients are capable of inducing the accumulation of fat in vascular wall cells.     

Changes and significance of serum angiopoietin-2 levels in patients with coronary heart disease

Coronary heart disease (CHD) is characterized by inflammatory process and endothelial dysfunction. To investigate angiopoietin-2 (Ang-2) profiles, we evaluated serum Ang-2 levels in different types of CHD in 166 subjects. Ang-2 was measured by enzyme-linked immunosorbent assay. Serum Ang-2 levels were significantly elevated in patients with CHD and gradually increased with advance of CHD. Ang-2 was positively correlated with Gensini scores and hs-CRP. Ang-2 might have potential implication in detecting and monitoring the progression of CHD.     

NK cell compartment in patients with coronary heart disease

Background  

Viral and bacterial infections have been considered as a risk factor for Coronary Heart Disease (CHD). NK cells, as a first line of defense against those infections, may play a role in CHD development. Thus, the main aim of our study was to determine NK cell compartment in patients with CHD undergoing coronary artery by-pass grafting.     

Tetrahydrobiopterin increases insulin sensitivity in patients with type 2 diabetes and coronary heart disease

Tetrahydrobiopterin (BH(4)) is an essential cofactor of nitric oxide synthase that improves endothelial function in diabetics, smokers, and patients with hypercholesterolemia. Insulin resistance has been suggested as a contributing factor in the development of endothelial dysfunction via an abnormal pteridine metabolism. We hypothesized that BH(4) would restore flow-mediated vasodilation (FMD, endothelial-dependent vasodilation), which may affect insulin resistance in type 2 diabetic patients. Thirty-two subjects (12 type 2 diabetic subjects, 10 matched nondiabetic subjects, and 10 healthy unmatched subjects) underwent infusion of BH(4) or saline in a random crossover study. Insulin sensitivity index (S(I)) was measured by hyperinsulinemic isoglycemic clamp. FMD was measured using ultrasonography. BH(4) significantly increased S(I) in the type 2 diabetics [3.6 +/- 0.6 vs. 4.9 +/- 0.7 x 10(-4) dl.kg(-1).min(-1)/(microU/ml), P < 0.05], while having no effects in nondiabetics [8.9 +/- 1.1 vs. 9.0 +/- 0.9 x 10(-4) dl.kg(-1).min(-1)/(microU/ml), P = 0.92] or in healthy subjects [17.5 +/- 1.6 vs. 18 +/- 1.8 x 10(-4) dl.kg(-1).min(-1)/(microU/ml), P = 0.87]. BH(4) did not affect the relative changes in brachial artery diameter from baseline FMD (%) in type 2 diabetic subjects (2.3 +/- 0.8 vs. 1.8 +/- 1.0%, P = 0.42), nondiabetic subjects (5.3 +/- 1.1 vs. 6.6 +/- 0.9%, P = 0.32), or healthy subjects (11.9 +/- 0.6 vs. 11.0 +/- 1.0%, P = 0.48). In conclusion, BH(4) significantly increases insulin sensitivity in type 2 diabetic patients without any discernible improvement in endothelial function.     

Direct coronary arterial stenting without predilatation in patients with coronary heart disease

The study was undertaken to evaluate the safety and efficiency of direct stenting versus routine stenting with predilation. It included 133 patients. By the decision of operators, direct stenting was conducted in 66 patients (71 stenoses) (Group 1). The remaining 67 patients (73 stenoses) underwent routine stenting with predilation (Group 2). The initial angiographic success of stenting was 100% in Group 1 and 98 in Group 2. Complications were absent. In the direct stenting group, technical problems occurred during a session in 9 (12%) cases. In this group the mean duration of fluoroscopy and the total duration of a session were much less than in the routine stenting group. The mean number of balloons used at dilation per stenosis and the number of dilation sessions per stenosis were much lower in Group 1 than in Group 2. The results of quantitative angiogram analysis before and after a session were similar in both patient groups. Six months following stenting, angiographic restenosis occurred in 7 (10%) patients in Group 1 and in 9 (12%) in Group 2. Direct stenting is a safe and effective treatment for non-occlusive coronary lesions without marked kinks and calcinosis. Direct stenting reduces the duration of fluoroscopy and the total duration of an operation by 50 and 22%, respectively, as compared to predilation stenting.     

Lipoprotein-associated phospholipase A2, and subsequent cardiovascular events and mortality among patients with coronary heart disease

Objective: The objective of this study is to evaluate the relevance of Lp-PLA₂ to risk prediction among coronary heart disease (CHD) patients.

Methods: Lp-PLA₂ activity was measured in 2538 CHD patients included in the Bezafibrate Infarction Prevention (BIP) study.

Results: Adjusting for patient characteristics and traditional risk factors, 1 standard deviation of Lp-PLA₂ was associated with a hazard ratio (HR) of 1.12 (95% confidence interval (CI): 1.00–1.25) for mortality and 1.03 (0.93–1.14) for cardiovascular events. Lp-PLA₂ did not significantly improve model discrimination, or calibration nor result in noteworthy reclassification.

Conclusions: Our results do not support added value of Lp-PLA₂ for predicting cardiovascular events or mortality among CHD patients beyond traditional risk factor.     

Heterodimerization of the alpha and beta isoforms of the human thromboxane receptor enhances isoprostane signaling

Isoprostanes are free radical catalyzed products of arachidonic acid that are elevated in pro-oxidant disease states. Two isoprostanes, 8-isoprostaglandin F(2alpha) (iPF(2alpha)III) and 8-isoprostaglandin E2 (iPE2III), act at the receptor for thromboxane A2 (the TP) to mediate pro-atherogenic effects in vivo. We confirmed dimerization of the human TP isoforms, TPalpha and TPbeta, and determined the impact on isoprostane signaling. No overt changes in ligand binding at the TP were observed as a result of TPalpha/TPbeta coexpression. The response to iPF(2alpha)III or iPE2III was enhanced in HEK293 cells stably coexpressing TPalpha and TPbeta, as measured by inositol phosphate generation or intracellular calcium mobilization, relative to cells expressing TPalpha or TPbeta individually. In contrast, the response to traditional thromboxane analogs was unaltered. Augmented isoprostane signaling was similarly observed in HEK 293 cell transiently transfected with TPalpha and TPbeta. These results indicate that TPalpha/TPbeta dimerization enhances isoprostane-mediated signal transduction.     

Abdominal fat and risk of coronary heart disease in patients with peripheral arterial disease

Objective: We investigated whether the presence of concomitant coronary heart disease (CHD) in patients with peripheral arterial disease (PAD) can be explained by intra‐abdominal fat accumulation and compared different measures of adiposity as predictors of CHD in patients with PAD. Research Methods and Procedures: Data were collected from patients enrolled in the Second Manifestations of ARTerial disease (SMART) study, an ongoing prospective cohort study of patients with manifest vascular disease or vascular risk factors at the University Medical Centre Utrecht. The current analysis includes 315 patients, mean age 59 ± 10 years, who had PAD with (n = 79) or without (n = 236) CHD. Parameters of adiposity were measured, and intra‐abdominal fat and subcutaneous fat were measured ultrasonographically. Metabolic syndrome was defined according to Adult Treatment Panel III. Results: The prevalence of metabolic syndrome was higher among patients with CHD (63%) than among patients without CHD (48%). All parameters of adiposity indicated more fat in patients with CHD, except for subcutaneous fat. Waist circumference was associated with 64% higher prevalence of CHD (confidence interval, 20% to 123%) per 1 standard deviation increase in waist circumference after adjustment for age and sex. The odds ratio for waist circumference remained virtually the same after additional adjustment for the components of the metabolic syndrome and smoking. Discussion: An increased waist circumference, a crude measure of intra‐abdominal fat, is associated with an increased risk of concomitant CHD in patients with PAD.     

Prosthetic valves in adult patients with congenital heart disease: Rationale and design of the Dutch PROSTAVA study

Background

Data on long-term complications in adult patients with congenital heart disease (ACHD) and a prosthetic valve are scarce. Moreover, the influence of prosthetic valves on quality of life (QoL) and functional outcome in ACHD patients with prosthetic valves has not been studied.

Objectives

The primary objective of the PROSTAVA study is to investigate the relation between prosthetic valve characteristics (type, size and location) and functional outcome as well as QoL in ACHD patients. The secondary objectives are to investigate the prevalence and predictors of prosthesis-related complications including prosthesis-patient mismatch.

Methods

The PROSTAVA study, a multicentre cross-sectional observational study, will include approximately 550 ACHD patients with prosthetic valves. Primary outcome measures are maximum oxygen uptake during cardiopulmonary exercise testing and QoL. Secondary outcomes are the prevalence and incidence of valve-related complications including prosthesis-patient mismatch. Other evaluations are medical history, physical examination, echocardiography, MRI, rhythm monitoring and laboratory evaluation (including NT-proBNP).

Implications

Identification of the relation between prosthetic valve characteristics in ACHD patients on one hand and functional outcome, QoL, the prevalence and predictors of prosthesis-related complications on the other hand may influence the choice of valve prosthesis, the indication for more extensive surgery and the indication for re-operation.     

Refined anaesthesia for implantation of engineered experimental aortic valves in the pulmonary artery using a right heart bypass in sheep

The feasibility of an anaesthetic protocol developed for surgery during right heart bypass in sheep is reported. Seven female Suffolk sheep, weighing 25-35 kg, were selected for the study. Premedication consisted of midazolam and methadone (both 0.1 mg kg(-1) intravenously). Anaesthesia was induced with propofol (2-4 mg kg(-1)) and maintained with isoflurane in oxygen and continuous rate infusions of propofol (5-7 mg kg(-1 )h(-1)) and fentanyl (5 microg kg(-1) bolus, 5 microg kg(-1) h(-1)). Cisatracurium (0.2 mg kg(-1)) provided muscle relaxation. A standard roller pump was used for the extracorporeal circulation. Drugs administered to maintain blood pressure and heart rate within acceptable levels included phenylephrine (3-4 microg kg(-1)), ephedrine (0.1-0.2 mg kg(-1)), nitroglycerine (50-150 microg kg(-1) h(-1)) and metoprolol succinate (30-80 microg kg(-1)). Electrolytes were infused as needed. Postoperative analgesia was provided by an intercostal block (15 mL 0.5% bupivacaine + epinephrine), carprofen (4 mg kg(-1)) and an opioid (methadone 0.1 mg kg(-1) or buprenorphine 0.01 mg kg(-1)). One sheep became hypoxic during the bypass (PaO(2) 47.7 mmHg). Irregularities of the electrocardiogram were observed during manipulation of the heart in all animals. During the initial phase of the bypass, blood pressure decreased in all sheep, accompanied by dilatation of the heart and large intrathoracic veins in five sheep. With appropriate treatment, blood pressure was restored and easily maintained until the end of the bypass. Weaning from the bypass, using an infusion of nitrates, was smooth. One sheep required a blood transfusion because of severe blood loss and another sheep died postoperatively from respiratory complications. Minor irregularities of the electrocardiogram observed during manipulation of the heart were not life threatening and required no treatment. Decreases in blood pressure at the beginning of the bypass can be expected and require treatment. Nitrates are useful in avoiding volume overload during weaning. The anaesthetic protocol is acceptable for surgery under right heart bypass in sheep.     

Pharmacological actions of isoprostane metabolites and phytoprostanes in human and bovine pulmonary smooth muscles

We examined the responses to various isoprostane derivatives in bovine/human airway and pulmonary arteries. All biological activity of 15-F(2t)-IsoP was lost in its two major metabolites (15-keto-15-F(2t)-IsoP and 13,14-dihydro-15-keto-15-F(2t)-IsoP). We also examined the effects of several metabolites of 15-F(2t)-IsoP synthesized within our own laboratory-both epimers of 2,3-dinor-15-F(2t)-IsoP and of 2,3-dinor-5,6-dihydro-15-F(2t)-IsoP, as well as 20-carboxy-2,3,4,5-tetranor-15 oxo-5,6,13,14-tetrahydro-15-F(2t)-isoP)-finding none of these to have any substantial excitatory effect. Finally, several plant-derived isoprostanes ("phytoprostanes") synthesized within our laboratory elicited little or no excitatory response in these three pulmonary smooth muscle preparations. We conclude that, although isoprostane exhibit powerful constrictor effects on airway and pulmonary vascular smooth muscles, metabolic processing of those isoprostanes essentially abolishes those biological actions; also, the phytoprostanes lack any appreciable pharmacological activity on those smooth muscle preparations.