Reinhard Lorenz

IMPROVED AORTOCORONARY BYPASS PATENCY BY LOW-DOSE ASPIRIN (100 mg DAILY): Effects on Platelet Aggregation and Thromboxane Formation

Prevention of aortocoronary bypass occlusion by aspirin (ASA, 1 X 100 mg per day) was studied in a prospective double-blind trial of 83 patients. 60 (72%) were randomly allocated to ASA or placebo starting 24 h after operation. 90% of grafts in the ASA group and 68% in the placebo group were patent at four months. At least one anastomosis was occluded in 62% of the patients on placebo and in 27% of those on aspirin. Ventricular arrhythmias increased after surgery in more patients on placebo (12/18) than in patients on ASA (5/17). Platelet thromboxane formation on collagen tested before operation was significantly higher in patients in whom bypass occlusion developed (occlusion: 40 +/- 19, no occlusion: 25 +/- 13 ng/ml). A 100 mg dose of ASA per day effectively blocked platelet thromboxane formation and thromboxane-supported aggregation on collagen and was safe in the postoperative phase. No side effects were reported throughout the trial. The reduced toxicity with full efficacy favours a low and infrequent dosage of aspirin.

Supplementation with n-3 fatty acids from fish oil in chronic inflammatory bowel disease--a randomized, placebo-controlled, double-blind cross-over trial.

Abstract. Thirty‐nine patients with chronic inflammatory bowel disease were studied in a 7‐month, double‐blind, placebo controlled cross‐over trial of dietary supplementation with fish oil, which provided about 3.2 g n‐3 fatty acids per day. At control, biopsies from inflamed mucosa contained higher levels of arachidonic acid than uninvolved mucosa. Dietary n‐3 fatty acids were well tolerated and incorporated into plasma and enteric mucosa phospholipids at the expense of n‐6 fatty acids. The arachidonic acid‐derived prostanoid generation was reduced by fish oil and the extension and severity of macroscopic bowel involvement was moderately improved. In patients with Crohns disease, clinical activity was unchanged by fish‐oil supplementation. In patients with ulcerative colitis, clinical disease activity fell during fish oil supplementation and thereafter: this was not significant however. Despite a moderate reduction in inflammatory lipid mediators by dietary n‐3 fatty acids and limited morphological improvement in chronic inflammatory bowel disease, the clinical benefit seems to be confined to patients with ulcerative colitis.

Cardiovascular and Cerebrovascular Comorbidities of Hypokalemic and Normokalemic Primary Aldosteronism: Results of the German Conn’s Registry

CONTEXT Primary aldosteronism (PA) is associated with vascular end-organ damage. OBJECTIVE Our objective was to evaluate differences regarding comorbidities between the hypokalemic and normokalemic form of PA. DESIGN AND SETTING This was a retrospective cross-sectional study collected from six German centers (German Conns registry) between 1990 and 2007. PATIENTS Of 640 registered patients with PA, 553 patients were analyzed. MAIN OUTCOME MEASURES Comorbidities depending on hypokalemia or normokalemia were examined. RESULTS Of the 553 patients (61 +/- 13 yr, range 13-96), 56.1% had hypokalemic PA. The systolic (164 +/- 29 vs. 155 +/- 27 mm Hg; P < 0.01) and diastolic (96 +/- 18 vs. 93 +/- 15 mm Hg; P < 0.05) blood pressures were significantly higher in hypokalemic patients than in those with the normokalemic variant. The prevalence of cardiovascular events (angina pectoris, myocardial infarction, chronic cardiac insufficiency, coronary angioplasty) was 16.3%. Atrial fibrillation occurred in 7.1% and other atrial or ventricular arrhythmia in 5.2% of the patients. Angina pectoris and chronic cardiac insufficiency were significantly more prevalent in hypokalemic PA (9.0 vs. 2.1%, P < 0.001; 5.5 vs. 2.1%, P < 0.01). Overall, cerebrovascular comorbidities were not different between hypokalemic and normokalemic patients, however, stroke tended to be more prevalent in normokalemic patients. CONCLUSIONS Our data indicate a high prevalence of comorbidities in patients with PA. The hypokalemic variant is defined by a higher morbidity than the normokalemic variant regarding some cardiovascular but not cerebrovascular events. Thus, PA should be sought not only in hypokalemic but also in normokalemic hypertensives because high-excess morbidity occurs in both subgroups.

Mildly oxidized LDL induces platelet aggregation through activation of phospholipase A2

Native LDL and LDL oxidized under various conditions were compared in terms of their ability to activate platelets. Native LDL did not induce platelet shape change or aggregation, even at high concentrations (2 mg protein/mL). LDL was mildly oxidized with either CuSO4 (mox-LDL) or 3-(N-morpholino)sydnonimine (SIN-1-LDL). Analysis of mox-LDL and SIN-1-LDL showed a small increase of dienes (E234nm from 0.28 +/- 0.04 to 0.55 +/- 0.09, mean +/- SD) and thiobarbituric acid-reactive substance (from 0 to 10.6 +/- 1.5 nmol/mg, mean +/- SEM), no change in apo B electrophoretic mobility, and a minor (12% to 30%) decrease in polyunsaturated fatty acid content. Interestingly, this small oxidative modification of LDL dramatically changed its effect on platelets. Irreversible aggregation and secretion were induced by a threshold concentration of 0.4 mg protein/mL. In contrast, LDL thoroughly oxidized with CuSO4 (ox-LDL) did not aggregate platelets. Although mox-LDL was depleted in antioxidants (alpha- and gamma-tocopherol, alpha- and beta-carotene, and other carotenoids), incubation of mox-LDL with exogenous alpha-tocopherol did not reverse its ability to induce platelet aggregation and secretion. Preincubation of platelets with the cyclooxygenase inhibitor aspirin or the phospholipase A2 inhibitors trifluoperazine, quinacrine, 4-bromophenacyl bromide, and propranolol completely prevented platelet aggregation and secretion caused by mox-LDL or SIN-1-LDL. These results indicate that mildly oxidized LDL activates platelets through a phospholipase A2/cyclooxygenase-dependent pathway. The complete inhibition of mox-LDL-induced platelet aggregation by aspirin could contribute to its beneficial effect in cardiovascular disease.

Effects of Dietary Fish Oil on Ventricular Premature Complexes

For ethical and practical reasons, in this study the antiarrhythmic potential of fish oil was evaluated in patients free from complex ventricular arrhythmias and severe heart failure. Although subjects without overt structural heart disease had ventricular arrhythmias that were not associated with an increased risk for sudden cardiac or coronary death, recent data suggest that frequent VPCs in patients similar to our study population may reflect subclinical cardiac disease amenable to the multiple beneficial actions of n-3 fatty acids. The potential and safety of fish oil as a treatment for more complex cardiac arrhythmias or arrhythmias in higher risk patients with more severe heart disease deserve further study.

The expression of the lectin-like oxidized low-density lipoprotein receptor (LOX-1) on human vascular smooth muscle cells and monocytes and its down-regulation by lovastatin

Accumulation of oxidatively modified low-density lipoprotein (oxLDL) in the vascular wall is a characteristic feature of atherosclerosis. oxLDL can be taken up into monocytes, smooth muscle cells, and endothelial cells by several known scavenger receptors such as scavenger receptor class A I and II, CD36, and CD68. A new lectin-like oxLDL receptor (LOX-1) was recently found in bovine and human endothelial cells. We studied whether LOX-1 is also expressed in other cells present in the atherosclerotic lesion and whether its expression can be modified. We found LOX-1 expression in human blood monocytes, umbilical smooth muscle and endothelial cells, and 3T3 fibroblasts. LOX-1 mRNA expression in monocytes could be significantly suppressed by lovastatin. Thus, LOX-1 expression is not restricted to endothelial cells and its down-regulation by HMG-CoA reductase inhibitors could contribute to the clinical benefits of these drugs.

Adrenal Venous Sampling Evaluation of the German Conn's Registry

In patients with primary aldosteronism, adrenal venous sampling is helpful to distinguish between unilateral and bilateral adrenal diseases. However, the procedure is technically challenging, and selective bilateral catheterization often fails. The aim of this analysis was to evaluate success rate in a retrospective analysis and compare data with procedures done prospectively after introduction of measures designed to improve rates of successful cannulation. Patients were derived from a cross-sectional study involving 5 German centers (German Conns registry). In the retrospective phase, 569 patients with primary aldosteronism were registered between 1990 and 2007, of whom 230 received adrenal venous sampling. In 200 patients there were sufficient data to evaluate the procedure. In 2008 and 2009, primary aldosteronism was diagnosed in 156 patients, and adrenal venous sampling was done in 106 and evaluated prospectively. Retrospective evaluation revealed that 31% were bilaterally selective when a selectivity index (cortisol adrenal vein/cortisol inferior vena cava) of ≥2.0 was applied. Centers completing <20 procedures had success rates between 8% and 10%. Overall success rate increased in the prospective phase from 31% to 61%. Retrospective data demonstrated the pitfalls of performing adrenal venous sampling. Even in specialized centers, success rates were poor. Marked improvements could be observed in the prospective phase. Selected centers that implemented specific measures to increase accuracy, such as rapid-cortisol-assay and introduction of standard operating procedures, reached success rates of >70%. These data demonstrate the importance of throughput, expertise, and various potentially beneficial measures to improve adrenal vein sampling.

Risk factors associated with a low glomerular filtration rate in primary aldosteronism.

CONTEXT Primary aldosteronism (PA) is associated with vascular end organ damage. OBJECTIVE We evaluated the newly established German Conns Registry for evidence of renal impairment and compared the data with those from hypertensive subjects of a population-based survey. DESIGN We conducted a case-control study. PATIENTS AND CONTROLS A total of 408 patients with PA from the Conns registry treated in five German centers were matched for age, sex, and body mass index in a 1:1 ratio with 408 hypertensive control subjects from the population-based F3 survey of the Kooperative Gesundheitsforschung in the region of Augsburg (KORA). MAIN OUTCOME MEASURES We measured serum creatinine and calculated glomerular filtration rate (GFR). RESULTS The percentage of patients with a serum creatinine concentration above the normal range of 1.25 mg/dl was higher in patients with PA than in hypertensive controls (29 vs. 10%; P < 0.001). Regression analysis showed that age, male sex, low potassium, and high aldosterone concentrations were independent predictors of a lower GFR. Adrenalectomy reduced systolic blood pressure from a mean of 160 to 144 mm Hg. In parallel, we observed an increase in serum creatinine and a decrease of GFR from 71 to 64 ml/min (P < 0.001). A similar trend was seen after spironolactone treatment. CONCLUSIONS In a large cohort of patients with PA, markers of disease activity such as plasma aldosterone and serum potassium are independent predictors of a lower GFR. Specific interventions, such as adrenalectomy or spironolactone treatment, are associated with a further decline in GFR.

Lovastatin reduces expression of the combined adhesion and scavenger receptor CD36 in human monocytic cells

The thrombospondin and collagen receptor CD36 was recently found to function, also, as a dominating scavenger receptor for oxidized low-density lipoproteins (oxLDL). Thus, CD36 might be a key factor in monocyte adhesion and foam cell formation. We, therefore, studied CD36 expression in monocytic cells under conditions of cholesterol depletion and overload. Human monocytic U937 cells were cultured under control conditions and in the presence of lovastatin, native, and oxLDL. The expression of lipoprotein receptors was measured by quantitative reverse transcriptase polymerase chain reaction (RT-PCR) and fluorescence-activated cell sorting (FACS). In sharp contrast to the feedback-controlled ApoB100 specific receptor for native low-density lipoprotein (LDL-R), CD36 expression was significantly reduced by lovastatin in a dose-dependent manner, both at the RNA and protein level, resulting in decreased cellular oxLDL binding. The addition of mevalonate completely reversed lovastatin effects, whereas excess LDL was only partially effective. Similarly to native LDL, oxLDL reduced LDL-R transcription, but did not affect CD36 transcription. CD36 protein surface expression fell, however, due to internalization of CD36 loaded with oxLDL. In summary, monocytic expression of CD36, in contrast to the native LDL-R, is reduced by cholesterol synthesis inhibition and not by feedback inhibition from substrate overexposure. CD36 suppression is a new pharmacological action of lovastatin that may contribute to its clinical benefit by attenuating monocyte adhesion and foam cell formation, key steps in atherosclerosis.

Downregulation by tumor necrosis factor-α of monocyte CCR2 expression and monocyte chemotactic protein-1-induced transendothelial migration is antagonized by oxidized low-density lipoprotein : A potential mechanism of monocyte retention in atherosclerotic lesions

The subintimal infiltration with monocytes is crucially involved in the development of complex atherosclerotic plaques. Monocyte chemotactic protein-1 (MCP-1) and its receptor CCR2 are important for monocyte extravasation and formation of atherosclerotic lesions. However, mechanisms of monocyte persistence in atherosclerotic plaques remain to be elucidated. Flow cytometric analysis revealed that monocytoid Mono Mac 6 cells that had transmigrated endothelium towards a MCP-1 gradient expressed higher levels of CCR2 than the non-migratory fraction, while input cells were intermediate, suggesting that high CCR2 levels are essential for transendothelial chemotaxis. Pretreatment of Mono Mac 6 cells or isolated human blood monocytes with the inflammatory cytokine tumor necrosis factor (TNF)-alpha dose- and time-dependently reduced MCP-1-induced transendothelial chemotaxis, which was inhibited by the CCR2 receptor antagonist 9-76 analog. This was paralleled by a decrease in CCR2 surface protein and mRNA expression. as assessed by flow cytometry and reverse transcription-polymerase chain reaction, inferring that inhibition of monocyte transmigration was due to downregulation of CCR2 to levels insufficient for chemotaxis. In contrast, treatment of monocytes with oxidized low-density protein (oxLDL) containing oxidized lipids, such as cholesteryl linoleate 13-hydroxide. but not with LDL, increased CCR2 protein and mRNA expression. Notably, oxLDL counteracted the TNF-alpha-mediated downregulation of CCR2 and CCR2-dependent transendothelial chemotaxis. Macrophage-colony-stimulating factor hardly affected CCR2 expression and function, suggesting that differentiation was not responsible for effects on CCR2. In conclusion, TNF-alpha impairs MCP-1-induced transendothelial migration of monocytes by downregulating CCR2 which appears critical for migration. Exposure to oxLDL antagonized the effects of TNF-alpha, and may thus contribute to monocyte retention and perpetuation of a chronic inflammatory reaction in unstable atherosclerotic lesions.