Cholesterol reduction in cardiovascular disease. Clinical benefits and possible mechanisms

Neuroimmunologic implications in coronary artery disease

In this review, the role of the macrophage in the pathophysiology of coronary artery disease (CAD) is examined. The central interaction of macrophage, endothelial cell and smooth muscle cell in the context of hyperlipidemia is considered. The macrophage appears to be at the beginning of a chain of events that starts with elevated low density lipoprotein (LDL). Stress, particularly in those with a core hostility, may be associated not only with higher catecholamine levels but also with higher serum lipid levels. These lipids will in turn be processed to oxidized LDL by macrophage and endothelial cells. Oxidized LDL molecules will contribute to atherosclerotic plaquing. A side effect of such plaque formation may be a diminished vasodilatory response to the nitric oxide (NO) produced by macrophages and endothelium. Indeed, paradoxical vasoconstriction occurs in atherosclerosis in response to neurotransmitters such as serotonin and acetylcholine, which under normal circumstances cause vasodilation. There also is evidence that both macrophages and endothelial cells can regulate NO production through a specific mu 3 morphine receptor, an effect that can be blocked by naloxone. The clinical effectiveness of morphine and nitroglycerin in CAD patients may relate to these mechanisms. More research will be needed to elucidate the neuroimmunologic basis for atherosclerosis with prospects for better treatment and management in future.

Effects of 1 year of growth hormone therapy on serum lipoprotein levels in growth hormone-deficient adults. Influence of gender and Apo(a) and ApoE phenotypes

We investigated the influence of gender and apoE and apo(a) phenotypes as well as the effect of the metabolic effects of growth hormone (GH) on the effect of GH therapy on serum lipoprotein concentrations in GH-deficient (GHD) adults. Forty-four consecutive patients, 30 men and 14 women aged 46.5 (range, 19 to 76) years with GHD due mainly to pituitary tumors, were treated with recombinant human GH for 12 months. Serum concentrations of lipoproteins, insulin, thyroxine, and insulin-like growth factor-I were determined, body composition was assessed by bioelectrical impedance, and apo(a) and apoE phenotypes were analyzed. Lipoprotein(a) [Lp(a)] concentrations in the GHD subjects were compared with a gender- and apo(a) phenotype-matched control group. After 12 months of GH treatment, the total cholesterol, LDL cholesterol, and apoB concentrations decreased, the HDL cholesterol and apoE concentrations increased, and the apoA-I and triglyceride concentrations were unchanged. Before treatment, the Lp(a) concentration was similar to that in the control group. However, after 12 months of treatment, the Lp(a) concentration had increased by 44% and 101% above baseline and the control group, respectively. Men and women responded differently to GH, with a more marked increase in Lp(a) concentration and fat-free mass and a more pronounced decrease in body-fat mass in men. Apo(a) phenotypes had no major influence on the effect of GH therapy. The only significant difference between apoE phenotypes was a higher baseline Lp(a) concentration among apoE4 heterozygotes.(ABSTRACT TRUNCATED AT 250 WORDS)

Corticosteroid withdrawal after liver transplantation

BACKGROUND

Long-term side effects of corticosteroids (CSs) result in > major morbidity for recipients of orthotopic liver transplants (OLT). We instituted a program of CS withdrawal among OLT recipients to quantify the contribution of CS to adverse clinical sequelae and to determine whether long-term CS administration is necessary to avoid rejection.

METHODS

Recipients who had normal allograft function on CS, cyclosporine, and azathioprine more than 1 year after OLT were offered CS withdrawal during 12 to 22 weeks. Patients underwent routine clinical monitoring and laboratory studies. Continuous variables were compared by paired t test analysis.

RESULTS

CSs were discontinued in 51 recipients; 45 (88%) of 51 patients remain steroid-free after a mean follow-up of 13.8 months (range, 4 to 36). CS therapy was reinstituted in 6 patients who had abnormal transaminase levels during routine follow-up. Among the patients who remain off CS, there were no significant changes in blood pressure, transaminase, alkaline phosphatase, bilirubin, or glucose levels during the study period. Mean number of blood pressure medications decreased from 0.7 +/- 0.1 to 0.4 +/- 0.1 (p = 0.007). Cholesterol decreased from 217 +/- 8 mg/dl on CS to 204 +/- 9 mg/dl at 1 month (p = 0.0001), 183 +/- 10 mg/dl at 3 months (p = 0.0001), 198 +/- 8 mg/dl at 6 months (p = 0.04), 213 +/- 11 mg/dl at 12 months (p = 0.01), 209 mg/dl +/- 16 at 18 months (p = 0.02), and 183 +/- 19 mg/dl at 24 months (p = 0.2) off CS. Weight loss occurred in 88% of patients and averaged 9.5 pounds.

CONCLUSIONS

CS therapy can be successfully withdrawn without precipitating rejection in liver transplant recipients who have stable graft function 1 year after OLT. The incidence and severity of hypertension and hypercholesterolemia are reduced in patients whose CSs have been withdrawn.

Atherosclerosis, oxidative stress, and antioxidant protection in endothelium-derived relaxing factor action

The vascular endothelium plays a central role in the regulation of vascular function. In particular, the local release of endothelium-derived relaxing factor (EDRF) regulates vascular tone and prevents platelet adhesion to the vascular wall. Impairment of EDRF action develops early in atherosclerosis and, in part, contributes to platelet deposition and vasospasm involved in the clinical expression of coronary artery disease. Recent evidence suggests that an imbalance between vascular oxidative stress and antioxidant protection is involved in the development of this vascular dysfunction. In this report, the relation between oxidative stress, atherosclerosis, and abnormal EDRF action is reviewed with particular attention to the effects of antioxidant supplementation in animal models of atherosclerosis and hypercholesterolemia.