Pattern of red blood cells and platelets cholesterol and fatty acids in homozygous familial hypercholesterolemic patients treated with LDL-apheresis

Two homozygous familial hypercholesterolemic patients were treated with dextran-sulfate cellulose LDL-apheresis (DSC-LDL/A). We evaluated qualitatively and quantitatively, red cell and platelets membrane cholesterol and fatty acids, before and after LDL-apheresis. Fatty acids and cholesterol of red blood cells and platelets were determined by gas-chromatographic technique. We failed to observe any quantitative or qualitative modification, as far as the youngest patient (MD) is concerned. Only in the oldest patient (SM), docosaesanoic acid (22:6) values, were significantly reduced by LDL-A on quantitative basis. In the same patient, also mirystic acid (14:0) values, were significantly decreased as determined by qualitative method. The above mentioned fatty acids were significantly changed in platelets on treatment with LDL-apheresis performed on weekly basis.

Low-density lipoprotein-apolipoprotein B metabolism following apheresis: simulation studies of mass changes and tracer kinetics

Low-density lipoprotein (LDL) apheresis is an effective method to treat severe hyperlipoproteinemia such as heterozygous familial hypercholesterolemia (FH). It is unknown whether apheresis induces changes in metabolic parameters of LDL-apolipoprotein B (apoB) such as the fractional catabolic rate (FCR) or production rate. We performed simulation studies to determine the effect of potential changes in the LDL FCR on LDL-apoB mass and on exogenous and endogenous tracer studies. For these studies, we assumed a two-compartment LDL model and the following metabolic parameters: plasma LDL-apoB, 180 mg.dL(-1); LDL-apoB production rate, 36 mg.dL(-1).d(-1) (approximately 14.4 mg.kg(-1).d(-1)); and LDL-apo FCR, 0.2 d(-1). It was also assumed that apheresis instantaneously decreased the LDL-apoB concentration to 60 mg.dL(-1) and that LDL-apoB production was not perturbed. The simulations examined three possible outcomes: (1) no change in FCR, (2) a temporary doubling in FCR, and (3) a temporary tripling in FCR. Monoexponential models were fit to the rebound of LDL-apoB mass data generated using the different FCRs. In no instance did the FCR determined from the fit match the FCR used to generate the data; FCRs were either higher or lower than the original FCR used to generate the data. Simulations of the kinetics of exogenously labeled LDL showed that if apheresis was performed on day 7 of a turnover study, it would be possible to detect large changes in LDL-apoB FCR. In contrast, during an endogenous labeling study, potential increases in FCR induced by apheresis may not be detected. However, our simulations do show that endogenous labeling studies performed before and after apheresis should yield data that will permit detection of changes in the FCR. Thus, these studies indicate that large differences in the LDL-apoB FCR induced by apheresis can be detected by either an exogenous tracer experiment perturbed by apheresis or by endogenous labeling experiments performed before and after apheresis. Small changes in the FCR that may be induced by apheresis will probably be indistinguishable from experimental noise.

Long-term effects of low-density lipoprotein apheresis using an automated dextran sulfate cellulose adsorption system. Liposorber Study Group

The short-term effectiveness of low-density lipoprotein (LDL) apheresis using a dextran sulfate cellulose adsorption column technique was previously examined in a 9-center, 22-week controlled trial in 64 patients with familial hypercholesterolemia (FH) who did not adequately respond to diet and drug therapy. Forty-nine patients (40 treatment, 9 controls) subsequently received LDL apheresis procedures as part of an optional follow-up phase. This study reports on the long-term safety, lipid lowering, and clinical efficacy of LDL apheresis for the 5-year period that includes both the initial controlled study and follow-up phase. During this time, patients received a total of 3,902 treatments of which 3,314 treatments were given during the follow-up phase. Adverse events were infrequent, occurring in 142 procedures (3.6%). Immediate reduction in LDL cholesterol was 76% both in homozygotes and in heterozygotes. Patients with homozygous FH had a progressive decrease in pretreatment LDL cholesterol level along with an increase in high-density lipoprotein (HDL) cholesterol level. There was no appreciable change in pretreatment lipoprotein level over time in heterozygotes. The rate of cardiovascular events during therapy with LDL apheresis and lipid-lowering drugs was 3.5 events per 1,000 patient-months of treatment compared with 6.3 events per 1,000 patient-months for the 5 years before LDL apheresis therapy. These findings support the long-term safety and clinical efficacy of LDL apheresis in patients with heterozygous and homozygous FH who are inadequately controlled with drug therapy.

[Screening and treatment of children and adolescents with hypercholesterolemias and dyslipidemias]

Evidence was provided that atherogenesis develops for several decades before pathological changes are manifested. It may thus be stated, that the "incubation period" of atherosclerotic pathological consequences is very long but it is reduced markedly already from childhood and adolescence in subjects with an atherogenic lipoprotein phenotype. Atherogenic lipoprotein phenotype comprises subjects suffering from one or more, frequently from a combination of several of the following metabolic indicators: hypercholesterolaemia, elevated levels of LDL-cholesterol, apolipoprotein B, lipoprotein (a), reduced levels of HDL-cholesterol and apolipoprotein A-1. The atherogenic lipoprotein phenotype is in 95% conditioned by inborn metabolic errors, i.e. familial hyperlipoproteinaemia and dyslipoproteinaemia. In the population the following are encountered most frequently: combined familial hyperlipidaemia, familial hypertriacylglycerolaemia and familial hypercholesterolaemia. Active screening and treatment of children and adolescents from these affected families is of great importance in primary prevention of atherosclerotic complications in adult age.

Serum amyloid A and P protein levels are lowered by dextran sulfate cellulose low-density lipoprotein apheresis

The present study describes the short-term effect of dextran sulfate cellulose (DSC) low-density lipoprotein (LDL) apheresis using a plasma separator equipped with a polysulfone (PS) membrane filter (PS/DSC-LDL apheresis) on the serum amyloid A (SAA) and P (SAP) protein levels during treatment in a patient with familial hypercholesterolemia (type IIa, heterozygote). PS/DSC-LDL apheresis markedly lowered both the SAA (reduction percentage, 84.1+/-8.2%) and SAP (91.4+/-5%) levels, which returned to their respective initial levels within 4 days. Experimentally, the levels of both proteins also decreased on passage through the DSC minicolumn without a PS membrane, indicating that the DSC resin had an affinity to both proteins. These results suggest that PS/DSC-LDL apheresis may be advantageous for amyloid protein accumulating disorders, including amyloidosis and atherosclerosis.

[Is detection and treatment of familial hypercholesterolemia indicated in children?]

Familial hypercholesterolaemia (FH) is a congenital metabolic disorder predisposing to severe atherosclerosis resulting in coronary heart disease sometimes even at early adult age. Children with FH lack the stigmata at physical examination and measuring the cholesterol level does not always enable the clinician to make the diagnosis. In about 70% of the cases, the diagnosis of FH in childhood can be made by means of molecular-biological examination, by demonstrating the underlying defect of the LDL cholesterol receptor gene. In the remaining cases, the combination of the positive family history for cardiovascular diseases and increased total cholesterol and LDL cholesterol levels should suggest the diagnosis of FH. Pharmaceutical agents inhibiting the cholesterol synthesis have been researched very little in children and are not registered in the Netherlands. Nevertheless, drug treatment of children with FH is advisable because of the better possibilities to make a definite diagnosis and the early occurrence of coronary heart disease. If this treatment were indicated before patients reach adult age, the question arises whether screening for FH of children in families in which this disorder prevails, should not be promoted more strongly.

[The effect of 4 years' of hypolipemic treatment on the width of the common carotid artery intima in patients with familial hyperlipidemias]

Sixty-four patients with familial hyperlipoproteinaemia were treated for almost four years by dietetic treatment and various hypolipidaemic drugs. In 25 patients with familial hypercholesterolaemia who had clinical signs of ischaemic heart disease total and LDL-cholesterol declined and the width of the intima of the common carotid artery diminished from 0.78 mm to 0.69 mm (p = 0.004). In the above artery the maximal flow rate of blood declined. The increase was, however, not statistically significant. In 12 patients with familial hypercholesterolaemia who suffered from ischaemic heart disease the width of the intima of the common carotid artery and maximum flow rate did not change, however, the diameter of the artery increased (from 6.3 to 6.6 mm, p = 0.034). In 27 patients with familial combined hyperlipidaemia during the drop of cholesterol, LDL-cholesterol and triacylglycerols the width of the intima of the common carotid artery diminished (from 0.72 to 0.67 mm, p = 0.044), the diameter of the artery increased (from 6.1 to 6.4 mm, p = 0.014). The authors assume that the reduction of the width of the intima during hypolipidaemic treatment reflected the decline of cholesterol in the arterial wall and is a favourable sign which indicates possible regression of atherosclerosis.

Decreased production of low density lipoprotein by atorvastatin after apheresis in homozygous familial hypercholesterolemia

Apheresis only partially controls raised low density lipoprotein cholesterol levels in patients with homozygous familial hypercholesterolemia, who usually respond poorly to lipid-lowering drugs. The efficacy and mechanism of action of a new 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, atorvastatin, was therefore investigated in seven homozygotes undergoing apheresis. One receptor-negative and six receptor-defective homozygotes undergoing plasma exchange or LDL apheresis every 2 weeks were studied during 2 months each on placebo and on atorvastatin 80 mg daily. Changes in plasma lipids and mevalonic acid, an index of cholesterol synthesis, were measured and the kinetics of the rebound of low density lipoprotein cholesterol and apolipoprotein B after apheresis were analyzed. All subjects had significant improvements on atorvastatin. Mean decreases in low density lipoprotein cholesterol were 31% greater both pre- and post-apheresis on atorvastatin compared with placebo, accompanied by a 63% decrease in mevalonic acid. Percentage changes in low density lipoprotein cholesterol and mevalonic acid were closely correlated (r = 0.89, P = 0.007). The mean production rates of low density lipoprotein cholesterol and apolipoprotein B were 21% and 25% lower, respectively, on atorvastatin than on placebo (P < 0.005 and <0.02) but changes in mean fractional clearance rates were not statistically significant. We conclude that atorvastatin enhances the efficacy of plasma exchange and low density lipoprotein apheresis in patients who lack low density lipoprotein receptors. This effect appears to be due to marked inhibition of cholesterol synthesis which results in a decreased rate of production of low density lipoprotein.

LDL apheresis in a homozygous familial hypercholesterolemic child aged 4.5

Preliminary experience with the efficacy and safety of dextran sulfate cellulose low-density lipoprotein (LDL) apheresis for the treatment of a 4.5-year-old girl with homozygous familial hypercholesterolemia and coronary artery disease is reported. The decrease of the most atherogenic apolipoprotein B-containing lipoproteins, low-density lipoprotein (LDL) and lipoprotein(a) (Lp [a]), were in the ranges of 63.1-68.7%, and 52.5-58.6%, respectively. The child tolerated LDL apheresis without any clinically significant complications. Therefore, she was submitted to a long-term program of treatment at intervals of 15 days. The experience suggests the possibility of an early beginning of extracorporeal treatment with LDL apheresis in children severely affected by homozygous or double heterozygous familial hypercholesterolemia.

[Severe stenosis of the right coronary artery in a 15-year-old girl with type IIa hypercholesterolemia: successful treatment with stent implantation]

Coronary artery stenosis with need for therapy is rarely seen in childhood. A 15-year-old girl with hypercholesterinaemia type II a was undergoing lipid aphereses therapy (once or twice a week) since she was 6 years old. The girl was seen in our hospital with stenocardia and depression of the ST-segment in the inferior ECG leads at rest. Myocardial scintigraphy with technetium 99 showed an ischemia of the infero-lateral left ventricular myocardium. During selective coronary angiography a 90% stenosis of the proximal right coronary artery over a distance of approximately 5 mm close to the ostium was found. Post stenotic dilatation of the vessel was obvious. In addition a diffuse 10% stenosis in the proximal and middle part of the right coronary artery was found. The left coronary artery appeared angiographically normal. After balloon dilatation, stent implantation was performed without complications with a 6 mm microstent. Reduction of the stenosis from 90% to 40% could be achieved. Ticlopidin 2 x 250 mg was started for thrombocyte aggregation inhibition. During the following 12 months the patient has been free of symptoms. Lipidaphareses has been continued as before. Stent implantation seems to be a successful treatment for coronary artery stenosis also in young patients.

Aggressive lipid lowering treatment in coronary atherosclerosis

Reduction of cholesterol by potent drugs in clinically symptomatic or asymptomatic patients with elevated cholesterol levels will substantially decrease the risk of coronary events. In selected cases more aggressive treatment of hyperlipidemia is necessary, such as in patients, homozygous for familial hypercholesterolemia, or subjects with severe coronary artery disease who are refractory to diet and drugs. LDL-apheresis, by which atherogenic lipoprotein particles are removed from the blood extracorporeally, is a therapeutic option in these cases. In this report a study is summarized, in which the effect of intervention with LDL-apheresis plus simvastatin was compared with conventional drug treatment alone in a group of patients with severe coronary artery disease with respect to changes in coronary atherosclerotic lesions and their functional impact.

Low-density lipoprotein apheresis for prevention and regression of atherosclerosis: clinical results

Hypercholesterolemia can be adequately controlled by appropriate diet and maximum lipid lowering drug therapy in most patients. Nevertheless, there exists a group of patients, including those with familial hypercholesterolemia (FH), who remain at high risk for the development or progression of premature coronary heart disease (CHD). For these patients additional measures such as surgery and low-density lipoprotein (LDL) apheresis have to be considered. The objective of this multicenter trial, which included 30 clinical centers (28 in Germany and one each in Scotland and Luxembourg), was to determine if repeated LDL apheresis using the Liposorber LA-15 system (Kaneka Corporation, Osaka, Japan) could lead to an additional acute and time averaged lowering of total cholesterol (TC) and LDL-cholesterol (LDL-C) in severely hypercholesterolemic patients whose cholesterol levels could not be controlled by appropriate diet and maximum drug therapy. A total of 6,798 treatments were performed on 120 patients, including 8 with homozygous FH, 75 with heterozygous FH, and 37 with unclassified FH or other hyperlipidemias from 1988 through 1994. The mean TC and mean LDL-C levels at baseline were 410.0 mg/dl and 333.9 mg/dl, respectively. LDL apheresis was performed once a week or at least once every 2 weeks in all patients. During treatment with the Liposorber system the mean acute percentage reduction was 52.6% for TC and 63.1% for LDL-C. Very low density lipoprotein cholesterol (VLDL-C) and triglycerides (TG) were also substantially reduced to 60.6% and 47.5%, respectively. Fibrinogen, a potential risk factor for CHD, was reduced by 26.2%. In contrast, the mean acute reduction of high density lipoprotein (HDL) was only 3.4%. During the course of the treatment, the time averaged levels of TC and LDL-C were reduced by approximately 39% and 50%, respectively, compared to baseline levels. The adverse events (AEs) were those generally associated with extracorporeal treatments. The most common AE was hypotension, with 69 episodes corresponding to 1% of all treatments reported in 44 of the 120 patients treated. All other kinds of AEs occurred in less than 0.2% of the treatments. The treatment with the Liposorber LA-15 system was overall well tolerated. It should be noted, however, that a more severe type of hypotensive reaction associated with flush, bradycardia, and dyspnea was reported in patients taking concomitant angiotensin converting enzyme (ACE) inhibitor medication. Except for such anaphylactoid-like reactions associated with the intake of ACE inhibitors, the Liposorber LA-15 system represents a safe and effective therapeutic option for patients suffering from severe hypercholesterolemia that could not be adequately controlled by diet and maximum drug therapy.

Clinical application and effectiveness of low-density lipoprotein apheresis in the treatment of coronary artery disease

The Low-Density Lipoprotein Apheresis Coronary Atherosclerosis Prospective Study (L-CAPS) examined whether or not combined low-density lipoprotein (LDL) apheresis and drug therapy apheresis could induce the regression of coronary atherosclerotic lesions in patients with familial hypercholesterolemia. Twenty-eight patients treated with LDL apheresis and drugs and 11 patients treated with drugs alone underwent sequential coronary angiography 2.5 years apart. The frequency of cases with regression or no change was significantly higher for the apheresis group than for the control group (p = 0.004). The LDL apheresis Angioplasty Restenosis Trial (LART) investigated the hypothesis that high plasma lipoprotein (a) (Lp[a]) levels were associated with increased incidences of restenosis after coronary angioplasty. Two days before and 5 days after angioplasty, 66 patients underwent LDL apheresis. The restenosis rates were 21% in the 42 patients whose Lp(a) levels were reduced > or = 50% and 50% in the 24 patients whose Lp(a) levels were reduced < 50% (p < 0.05). LDL apheresis is effective in the prevention of the progression of coronary atherosclerosis. Its potential application in restenosis prevention should be further investigated.

The retardation of progression, stabilization, and regression of coronary and carotid atherosclerosis by low-density lipoprotein apheresis in patients with familial hypercholesterolemia

The long-term effects of low-density lipoprotein (LDL) apheresis (LA) on the progression and regression of atherosclerosis were evaluated by angiographic and pathological findings as well as ultrasonography based studies, and the clinical significance of the treatment was evaluated. We studied 11 patients with familial hypercholesterolemia (FH), 2 with homozygous FH and 9 with severe heterozygous FH who received combined LA and drug therapy for a mean of 7.7 years. During the treatment period, the mean time-averaged level of LDL cholesterol was 181+/-52 mg/dl. According to the coronary angiographic results, 3 patients showed regression, 6 patients showed progression, and 2 patients showed no change. Cardiac events occurred in 6 patients. We pathologically examined at autopsy the coronary arteries of 1 FH patient who had received long-term LA therapy before death. The results revealed the process of scarring of atheromatous plaque, suggesting pathological regression correlated with the angiographic regression shown in serial angiograms taken during LA treatment. It was further suggested that the formation of an eccentric thick end wall lesion rich in collagen fiber prevented atheromatous plaque from tearing off. However, the annual progression rate of the mean maximal intima-media thickness in the common carotid artery was 0.0002 mm/year in the LA group, which was significantly lower than the mean of 0.251 mm/year seen in the control group (drug therapy only group). In the patients with heterozygous FH (9 patients), the annual progression rate was lowered to 0.0023 mm/year, suggesting regression. The findings of the present study indicate that patients with severe FH refractory to drug treatment may benefit from more aggressive cholesterol lowering treatments such as LA combined with cholesterol lowering drug therapy. The progression of atherosclerosis may be prevented, plaque may be stabilized (regressed), and clinical events may be reduced as seen with patients with non-FH hypercholesterolemia.

Clinical experience and future directions for low-density lipoprotein apheresis in the United States

The United States Liposorber Study was a 22 week randomized controlled study of low-density lipoprotein (LDL) apheresis with an optional follow-up phase. The procedure was found to acutely lower LDL cholesterol by up to 81%, have good tolerability, and produce a reduction in the frequency of cardiovascular events. Studies outside the United States have found therapy with LDL apheresis to be associated with a favorable clinical outcome including improved myocardial perfusion, but variable regression of coronary artery disease (CAD). Improvement in blood viscosity and endothelial function may help explain the symptomatic benefits observed with relatively small changes in angiography. Based upon favorable clinical experience, LDL apheresis using dextran sulfate cellulose columns has recently received approval for commercialization in the United States in patients with inadequate responses to diet and drug therapy and LDL levels > or = 200 mg with CAD present or LDL levels > or = 300 mg/dl without CAD.

Long term effect of LDL apheresis on coronary heart disease

LDL-apheresis is a treatment option for patients with coronary heart disease and severe hypercholesterolemia not adequately responding to drug treatment. 34 patients (21 men, 13 women), aged 47 +/- 9 years, with coronary heart disease and heterozygous familial hypercholesterolemia not adequately responsive to lipid lowering drugs received weekly (4 patients biweekly) LDL apheresis for 3.5 +/- 2.5 years, after 0.5 - 3.0 years simvastatin in the maximally tolerable dose was added. Baseline LDL cholesterol concentration under diet and lipid lowering drugs in the patients receiving immunoadsorption, dextran sulfate adsorption and HELP apheresis was 265.4 +/- 54.9, 230.8 +/- 75.8 and 253.7 +/- 55.7 mg/dl, respectively. The calculated mean LDL cholesterol concentration of the last 5 treatments of the observation period was 123.7 +/- 22.8, 126.8 +/- 26.7 and 138.8 +/- 19.7 mg/dl, respectively. The evaluation of coronary angiographies revealed a definite regression of coronary lesions in 3 patients (8.8%), in all other patients there was a stop in progression. 3 patients died of cardiac complications during the observation period. We conclude that aggressive lipid lowering with combined LDL-apheresis and drugs can stabilize coronary atherosclerosis in most patients with refractory hypercholesterolemia.

Platelet aggregation and lipoprotein levels in a patient with familial hypercholesterolemia after selective LDL-apheresis

Platelet aggregation was studied in a patient with familial hypercholesterolemia immediately after apheresis selective for low-density lipoprotein (LDL), a lipid-lowering procedure. This treatment reduced plasmatic levels of total and LDL-cholesterol, apo B, and triglyceride. Increased platelet aggregation was reduced immediately after the apheresis in whole blood as well as in platelet-rich plasma. However, aggregation in washed platelets remained unchanged after LDL-apheresis. In conclusion, in this patient reduction of LDL-cholesterol improved platelet function in the very short term.

Treatment of homozygous familial hypercholesterolemia with low density lipoprotein apheresis: a 4 year follow-up study

Hypercholesterolemia and elevated lipoprotein (a) (Lp[a]) levels are considered to be risk factors for the development and progression of premature atherosclerosis. The purpose of our report is to describe the effects of low density lipoprotein (LDL) apheresis (Liposorber system, Kanegafuchi Chemical Industrial Company LTD, Osaka, Japan) on serum lipoprotein concentrations and the clinical status in 2 male patients with homozygous familial hypercholesterolemia. Compared with pretreatment values, the posttreatment concentrations of total cholesterol, LDL cholesterol, and Lp(a) were significantly reduced by 50-60% (p < 0.0001). The concentration of high density lipoprotein (HDL) cholesterol was slightly affected. After one treatment session, LDL cholesterol and Lp(a) were decreased on average by 65% and then increased to reach about 70-75% of the pretreatment values before the next session. Prior to the treatment with LDL apheresis, each patient had suffered one myocardial infarction and had had 2 coronary angiographies. After treatment with LDL apheresis, neither cardiac complaints nor myocardial infarction were observed. The xanthomas were much decreased during the treatment or disappeared. We conclude that LDL apheresis can be continued safely and without major technical problems for several years. Apheresis effectively lowers the serum levels of total and LDL cholesterol. Furthermore, it reduces Lp(a), which is not influenced by lipid-lowering drugs. The reduction of LDL cholesterol and Lp(a) may delay the progression of the atherosclerotic process, thereby helping to reduce the risk of new episodes of coronary heart disease and thus extending the life expectancy in these patients.

Low density lipoprotein-apheresis decreases oxidized low density lipoproteins and monocyte adhesion to endothelial cells

The mutual interaction between monocytes and low density lipoprotein (LDL) in atherogenesis prompted a test of the hypothesis that LDL-apheresis could reduce the adhesive properties of monocytes to endothelium; and therefore interfere with a key mechanism in atheroma formation. Five patients affected by heterozygous familial hypercholesterolemia were studied. All patients received LDL-apheresis treatment with selective adsorption of LDL-cholesterol on dextran-sulphate columns. Low density lipoprotein particles were isolated by sequential preparative ultracentrifugation and subfractionated by ion exchange high performance liquid chromatography. Thiobarbituric acid reacting products of lipid peroxidation were measured fluorometrically. Vitamin E was estimated by high performance liquid chromatographic technique. Monocytes were isolated from patients blood before and 1 day after LDL-apheresis by Percoll gradient. The blood samples for monocyte adhesion were drawn from control subjects for 2 consecutive days. The adhesion of monocytes to an endothelial monolayer was evaluated by assaying the peroxidase content of the adherent monocytes. Low density lipoprotein-apheresis reduced total cholesterol (-65%; p < 0.01), LDL-cholesterol (-75%; p < 0.01), triglycerides (-51%; p < 0.05), and fibrinogen (-28%; p < 0.01). With LDL-apheresis treatment, a reduction of 54% in oxidized LDLs was observed; vitamin E concentration significantly increased in LDLs (+ 14.2%; p < 0.05). The monocyte adhesion decreased by approximately 61% after apheresis; the variation became statistically significant (-65%; p < 0.01) when endothelial cells were stimulated by lipopolysaccaride.

Arachidonic acid of platelet phospholipids is decreased after extracorporeal removal of plasma low density lipoproteins in patients with familial hypercholesterolemia

Platelet phospholipid composition was analyzed before and after extracorporeal removal of low density lipoproteins (LDL) by LDL apheresis in six patients with familial hypercholesterolemia. Elevated levels of total plasma cholesterol and the portion of plasma cholesterol carried by LDL were reduced by 56 and 66% after LDL apheresis. Platelet cholesterol contents remained unaffected. While the phosphatidylcholine (PC):sphingomyelin (SM) ratio in plasma lipoproteins was increased by 22% following apheresis, the same parameter was lowered by 14% in platelets. LDL apheresis induced decreases in the percentages of distinct molecular species containing arachidonic acid in platelet diacyl subgroups of PC, phosphatidylinositol (PI) and phosphatidylserine (PS) as well as in alkenylacyl (plasmalogen) phosphatidylethanolamine (PE). Directly after apheresis, the percentages of molecular species with arachidonic acid of diacyl PC, diacyl PI and alkenylacyl PE were reduced by 20, 23 and 8%, respectively. Two days after the procedure, total arachidonic acid of diacyl PC, diacyl PS and alkenylacyl PE was lowered by 11, 20 and 8%. Overall, the amount of phospholipid bound arachidonic acid was reduced by 16% after apheresis (from 79.1 to 66.4 nmol/10(8) platelets). The results are thus in agreement with previous data indicating decreased phospholipid bound arachidonic acid in red blood cells after apheresis (Engelman B. Bräutigam C, Kulschar R et al. Biochim Biophys Acta 1994:1196:154). Urinary 2,3-dinor thromboxane B2, an estimate of platelet thromboxane A2 (TXA2) production, tended to be decreased following the procedure. The percentage change in the TXA2 metabolite was positively related to the magnitude of change induced by apheresis in phospholipid bound arachidonic acid. In summary, the results suggest that in patients with hypercholesterolemia, the level of plasma LDL is an important determinant of the arachidonic acid content of several platelet phospholipids.

Decreased low-density lipoprotein oxidation after repeated selective apheresis in homozygous familial hypercholesterolemia

Familial hypercholesterolemia was the first genetic disorder recognized to cause myocardial infarction. Patients with homozygous familial hypercholesterolemia have rapidly progressive coronary atherosclerosis with angina pectoris, myocardial infarction, or sudden death at a young age. Selective apheresis on dextran sulfate cellulose columns reduces mortality and may induce regression of coronary lesions. These patients have both increased levels and prolonged circulation residence time of low-density lipoprotein (LDL), which is not removed by cellular receptor. LDL oxidation may play a pivotal role in atherogenesis. LDL undergoes oxidation before being taken up by macrophages and then transformed into arterial wall foam cells. The aim of this study was to investigate LDL oxidation in eight homozygous patients with familial hypercholesterolemia during repeated LDL apheresis. LDL lipid peroxidation, estimated by conjugated-diene absorbance at 234 nm, lipid peroxides, and malondialdehyde showed an increased resistance against oxidation after repeated LDL apheresis. This phenomenon was also observed in the oxidative indexes of protein moiety of LDL (apolipoprotein-B100 fragmentation, trinitrobenzenesulfonic acid reactivity, and electrophoresis agarose mobility). Similarly, cholesteryl esterification was decreased after LDL apheresis. Thus selective LDL apheresis not only decreases the pool of LDL, but it also induces changes that render LDL less susceptible to oxidation. This phenomenon might contribute to reduce coronary atherosclerosis and thus mortality of these particular patients.

Changes in bradykinin and prostaglandins plasma levels during dextran-sulfate low-density-lipoprotein apheresis

The negative charges of dextran-sulfate (DS) used for low-density-lipoprotein (LDL) apheresis initiate the intrinsic coagulation pathway in which plasma kallikrein acts on the high-molecular-weight kininogen to produce large amounts of bradykinin. This study was undertaken to assess whether bradykinin generated during DS LDL apheresis has any physiologic effects in vivo. The plasma levels of bradykinin, prostaglandins and cyclic guanosine monophosphate (cGMP) were compared. when either of two anticoagulants, heparin or nafamostat mesilate (NM), was used during DS LDL apheresis. Although anticoagulative action by NM depends on the inhibition of thrombin activity this substance also inhibits the activity of plasma kallikrein. During apheresis using heparin, the plasma levels of prostaglandin E2 (PGE2) increased significantly (5.6 +/- 1.2 (mean +/- SE, n = 4) pg/ml before apheresis and 33.4 +/- 13.2 after apheresis, p < 0.05) in association with an increase in bradykinin levels (17.9 +/- 2.6 pg/ml before apheresis and 470 +/- 135 after apheresis, p < 0.01). Interestingly, these changes were suppressed during apheresis using NM. There were no appreciable changes in cGMP during DS LDL apheresis with either of the anticoagulants. This finding suggests that bradykinin generated during apheresis has some pathophysiological effects via activation of the prostaglandin system. Our results support the view that in patients taking angiotensin-converting-enzyme inhibitors, the anaphylactoid reaction occurring during apheresis may be caused by an excessive rise in the bradykinin levels.

Peripheral vasoactivity in familial hypercholesterolemic subjects treated with heparin-induced extracorporeal LDL precipitation (HELP)

Hypercholesterolemia is associated with abnormalities in arterial vasoactivity which can be reversed with cholesterol-reducing therapies. Heparin-induced extracorporeal LDL precipitation (HELP), an invasive method for treating refractory hypercholesterolemia, causes regression of both xanthomas and atherosclerosis, but its effect on vasoactivity has not been investigated. We tested the effects of HELP on vasoactivity with an ultrasound system for continuous measurement of arterial flow velocity and end-diastolic diameter. We measured brachial artery vasoactivity before, during, and after a 5 min forearm vascular occlusion. Vasoactivity measurements were acquired from 6 subjects with familial hypercholesterolemia (FH) who had been treated chronically with HELP, immediately before and after each of 4 treatments, and from 12 age- and sex-matched normocholesterolemic subjects (2 matched with each HELP subject). Peak arterial dilation after cuff release, relative to the pre-occlusion diameter, was similar for the pre-treatment, post-treatment, and normocholesterolemic groups (0.29 mm pre-treatment, 0.30 mm post-treatment and 0.33 mm normocholesterolemic, P = NS). The slope of arterial diameter during occlusion was also similar for the three groups (-0.10 microm/s pre-treatment, 0.02 microm/s post-treatment, and 0.06 microm/s normocholesterolemic, P = NS). These two parameters are known to be decreased in hypercholesterolemic subjects to an extent which could be readily detected by the power of this study. Interestingly, one homozygous FH subject consistently demonstrated significant improvement in these two parameters immediately after HELP, suggesting an individual difference in arterial physiology. On average, FH patients treated chronically with HELP have similar vasoactivity to age- and sex-matched subjects with low risk for atherosclerosis. This result, in light of the many studies that have associated hypercholesterolemia with abnormal vasoactivity, suggests that chronic HELP therapy improves vasoactivity in patients with severe hypercholesterolemia.