Peter Schuff-Werner

Enhanced procoagulatory activity (PCA) of human monocytes/macrophages after in vitro stimulation with chemically modified LDL *

In cultured human monocytes/macrophages, surface expression of procoagulatory activity (PCA) was induced by chemically modified LDL (acetyl-LDL and MDA-LDL) in a dose- and time-dependent manner. Maximum PCA (30-fold increase) was detected after 24 h of culture with modified LDL at doses of 25-750 micrograms protein/ml. Using factor VII deficient human plasma and phospholipase C this PCA was identified as tissue thromboplastin activity (factor III). These results suggest a further atherogenic potential for modified LDL through stimulation of the conversion of fibrinogen to fibrin in the atheromatous lesion.

Antiinflammatory Agent BW 755 C in Ischemic Reperfused Porcine Hearts

The effect of the antiinflammatory compound BW 755 C on myocardial infarctions was evaluated in regionally ischemic reperfused hearts of 35 pigs. The left anterior descending coronary artery was occluded distally in 23 anesthetized pigs for 45 min and was reperfused for 24 h. The BW 755 C (10 mg/kg) was intravenously injected prior to ischemia in seven pigs (group A). A second dose of BW 755 C (5 mg/kg) was given after 4 h of reperfusion. Group B consisted of eight animals. They were treated with BW 755 C immediately before (10 mg/kg i.v.) and after 4 h of reperfusion (5 mg/kg). Another eight pigs served as controls. At the end of the experiments, infarct size was determined as the ratio of the infarcted myocardium (tetrazolium stain) over the risk region (fluorescent dye). Leukocyte infiltration of the risk region was histologically quantitated in one slice of each experiment. In a second set of experiments recovery of regional myocardial function of the risk region was determined by sonomicrometry during 2 weeks of reperfusion. The BW 755 C (10 mg/kg) was injected intravenously in six pigs before ischemia and at a dose of 5 mg/kg after 4 h of reperfusion. Six pigs served as controls. Hemodynamic parameters and total leukocyte blood count did not differ between the groups. Treatment protocol of group A reduced the infarct size from 72 ± 13% (control group) to 50.9 ± 12% (p < 0.005). Infarct size of group B (65 ± 16%) did not differ from control experiments. Leukocyte infiltration of the risk region was only attenuated in group A (p = 0.01) compared with the control group. The treatment protocol of group A, however, did not decrease the transmural extent of necrosis after 2 weeks of reperfusion. Furthermore, this therapy did not improve functional recovery of the risk region, suggesting that the beneficial effect observed after 24 h of reperfusion was later lost. It is concluded that BW 755 C, when given before ischemia and after reperfusion, limits myocardial infarct size determined after 24 h of reperfusion. This, however, does not necessarily imply ultimate salvage of jeopardized myocardium because the same treatment did not improve regional myocardial function and the transmural extent of necrosis after 2 weeks of reperfusion.

Heparin extracorporeal LDL precipitation (HELP) : an effective apheresis procedure for lowering Lp(a) levels

Heparin-induced extracorporeal low-density lipoprotein precipitation (HELP) is based on the precipitation of apolipoprotein B (apo B) containing lipoproteins with heparin at low pH (4.85). In in vitro experiments we could show that Lp(a) is quantitatively (> 99%) precipitated from plasma by heparin in the pH range 4.6-5.2. The acute changes in Lp(a) after a single HELP-LDL apheresis were investigated in twelve patients with Lp(a) concentrations > 30 mg/dl. A single treatment caused a highly significant decrease (62%) in the concentration of Lp(a), similar to the decrease (60%) observed for LDL-cholesterol. Analysis of the data from ten patients with different apo(a) phenotypes indicated that Lp(a) is eliminated with almost 100% efficiency in the extracorporeal circulation, irrespective of apo(a) phenotype and plasma concentration. The mean rate of recovery of Lp(a) following HELP-LDL apheresis was slightly slower than that of LDL-cholesterol. Plasma Lp(a) concentrations were monitored in seven patients over 2 years. Mean Lp(a) concentrations after 2 years were lower than pre-treatment levels, indicating that repeated elimination of the lipoprotein does not lead to an induction in its synthesis. HELP-LDL apheresis should be particularly suitable for treatment of patients with elevated LDL-cholesterol levels who are also at increased coronary risk because of high Lp(a) concentrations.

The effects of Trolox, a water-soluble vitamin E analogue, in regionally ischemic, reperfused porcine hearts

Myocardial protection by the water-soluble vitamin E analogue, Trolox, was investigated in 18 regionally ischemic, reperfused porcine hearts. The left anterior descending coronary artery was distally ligated for 45 min and was reperfused for three days. Five grams of Trolox (n = 9) were infused intravenously before coronary occlusion. Treatment was continued with an intravenous dose of 5 grams Trolox/24 hours until the end of the experiment. Infarct size was determined as the ratio of infarcted (tetrazolium stain) to ischemic myocardium (dye technique). Regional systolic shortening was assessed by sonomicrometry. Generation of free radicals by stimulated neutrophils was evaluated by luminol-enhanced chemiluminescence. Plasma concentrations of Trolox were measured by high-performance liquid chromatography. Aside from heart rate before ischemia, global hemodynamic values including calculated left ventricular oxygen consumption did not differ significantly between the two groups. Plasma concentrations of Trolox measured 1.8 +/- 0.3 mmol/l (before ischemia), 0.96 +/- 0.13 mmol/l (before reperfusion), 0.77 +/- 0.1 mmol/l (40 min of reperfusion), and 0.08 mmol/l (end of the experiment). Generation of free radicals by stimulated neutrophils was reduced by about 30% in the treatment group before ischemia and immediately before reperfusion, but was not reduced at the end of the experiment. Risk regions (control group 19.4 +/- 6 g, treatment group 19.3 +/- 7 g) and infarct sizes (control group 69.3 +/- 8%, treatment group 69.3 +/- 12%) were almost identical. Regional systolic shortening of a control segment and of the risk region were similar in both groups before ischemia, before reperfusion, and after 45 min of reperfusion. After 3 days of reperfusion, regional systolic shortening of the reperfused myocardium of the treated group had recovered to a significantly greater extent (P = 0.027). This parameter amounted to 9 +/- 6% in the treated group and to 3 +/- 3% in the control group. Improved functional recovery was not accompanied by higher tissue concentrations of adenosine triphosphate. It is concluded that the chosen treatment with Trolox does not reduce infarct size but accelerates functional recovery. This finding suggests that the mechanisms resulting in myocardial necrosis during ischemia/reperfusion and in post-ischemic myocardial dysfunction may differ.

Suppression of Leukocyte-Enhanced Cold Ischemia/Reperfusion Injury of Liver Endothelium with the Benzoquinone Antioxidant Idebenone

OBJECTIVE Despite the large body of evidence for a major role of neutrophils and oxidant stress, the exact pathogenesis of the early ischemia/reperfusion injury after cold preservation of the liver is not well understood. The potential benefit of an antioxidant on metabolic liver function during reperfusion has been demonstrated in several studies. MATERIALS AND METHODS We describe a cold storage/reperfusion damage model with isolated perfused pig livers, where the effects of neutrophils and idebenone, a recently developed benzoquinone antioxidant were studied. The integrity of sinusoidal endothelial cells (SEC) was estimated by hyaluronic acid concentration in perfusate and the expression of endothelial constitutive nitric oxide synthase (ecNOS) after reperfusion and compared to lipid peroxidation and antioxidant content. RESULTS Hyaluronic acid displayed the highest levels and ecNOS mRNA was most depressed in livers reperfused with neutrophils after 20 h cold storage; this was accompanied by an increase in lipid peroxidation (TBARS) and a breakdown of endogenous lipophilic antioxidants (alpha-tocopherol and coenzyme Q-10). These effects were attenuated, when neutrophils were excluded from reperfusion and almost completely abolished by the addition of 200 mumol/L idebenone. CONCLUSIONS These data suggest that a leukocyte-mediated damage based on reactive oxygen species markedly contributes to the reperfusion injury of SEC after cold preservation of the liver. Therefore, the presence of effective antioxidants in the early reperfusion phase may be beneficial for liver graft integrity.

Apolipoprotein A-1 and apolipoprotein B containing lipoprotein particles in coronary patients treated with extracorporal low density lipoprotein precipitation (HELP)

Evidence for chemical and biological heterogeneity of human plasma lipoprotein density classes has been steadily accumulating over the last 15 years. Furthermore, several recent reports have indicated potential clinical significance of certain lipoprotein subspecies as either atherogenic or antiatherogenic. It is generally accepted that lipid lowering treatments can retard or even reverse development of atherosclerotic lesions. However, very little is known about effects of various lipid lowering treatments on specific lipoprotein particles. The purpose of this study was to explore the effects of heparin induced extracorporal low density lipoprotein precipitation (HELP) on various subspecies of plasma lipoprotein particles defined primarily by their apolipoprotein composition. Using particle specific enzyme immunoassays, the immediate changes in lipoprotein particle profiles were analyzed after a single HELP treatment in 12 patients with angiographically documented coronary artery disease. In a separate group of 6 patients, particles were repeatedly measured over a period of 96 h following a HELP treatment. Single HELP treatment caused an immediate and highly significant decrease (67%) in the concentration of simple lipoprotein particles containing apolipoprotein B (apo B) as a sole apolipoprotein (LP-B). Various subspecies of complex particles containing apo B and other apolipoproteins (Lp-B-complex) were also decreased although to a lesser degree (44-53%). HELP treatment caused an insignificant, 3% decrease of lipoprotein particles containing apo A-I but no apo A-II (Lp-A-I) and a 6% decrease in the concentration of particles containing both apo A-I and apo A-II (Lp-A-I:A-II). During the 96-h period following HELP treatment various apo B containing particles recovered at different rates in different patients.(ABSTRACT TRUNCATED AT 400 WORDS)

Failure of iloprost to protect the regionally ischemic, reperfused porcine heart

The effect of iloprost (Schering AG, Berlin), a stable prostacyclin analogue, was investigated in ischemic, reperfused porcine hearts. The left anterior descending coronary artery (LAD) was distally occluded in 18 pigs for 45 min followed by 3-d of reperfusion. Nine pigs were continuously treated with iloprost at a dose of 25 ng/kg per min. Treatment was started as intracoronary infusion into the proximal LAD 10 min before occlusion. The intercoronary infusion was replaced by an intravenous infusion after 45 min of reperfusion, which was continued until the end of the experiment. Infarct size was determined as the ratio of infarcted (tetrazolium stain) to ischemic myocardium (dye technique). Regional systolic shortening was assessed by sonomicrometry. Myocardial concentrations of adenosine triphosphate were evaluated at the end of the experiment. Generation of free radicals by stimulated polymorphonuclear neutrophils was determined by luminol-enhanced chemiluminescence. Histologic and immunohistologic techniques were applied to characterize the myocardial inflammatory response. Global hemodynamics did not differ between the two groups. Neither infarct size (control group 68 +/- 18%, treated group 74 +/- 14%), recovery of systolic shortening (control group 3 +/- 6%, treated group 6 +/- 6%), nor myocardial adenosine triphosphate concentrations were improved by iloprost treatment. Myocardial inflammatory response remained unaffected by this treatment. The capacity of coronary venous, stimulated polymorphonuclear neutrophils to generate free radicals was slightly suppressed in the treated group before ischemia, at the end of ischemia and during early reperfusion. In this preparation, iloprost did not exhibit any beneficial effect on infarct size, recovery of systolic shortening and myocardial adenosine triphosphate concentrations.

Long-term clinical experience with HELP-LDL-apheresis in combination with HMG-CoA-reductase inhibitors for maximum treatment of coronary heart disease associated with severe hypercholesterolemia

Extracorporeal low density lipoprotein (LDL)-apheresis offers an adjunctive therapy to diet and drug treatment for reducing LDL concentrations in patients with excessively high cholesterol levels and those at high coronary risk. After nearly 4 years experience with the heparin-induced extracorporeal LDL/fibrinogen precipitation (HELP) system, based on heparin induced LDL precipitation at acidic pH, over 7,000 single aphereses have been performed on more than 100 patients in several clinics. Due to the simultaneous removal of LDL and fibrinogen, regular HELP-LDL-apheresis can normalize hemorrheologic parameters, thus explaining the observation of a rapid and lasting clinical improvement in signs and symptoms of coronary heart disease (CHD). The use of Simvastatin in combination with HELP significantly augments the reduction in LDL cholesterol to a level where regression of atherosclerotic lesions might be expected.