Seminars in vascular medicine最新文献

Metabolic syndrome of insulin resistance and depression are both considered important cardiovascular risk factors. The aim of this study was to ascertain a possible association between these conditions in a population sample of 116 subjects (54 males, 62 females, aged 60 +/- 8 and 60 +/- 9 years, respectively). A standard questionnaire-the Hospital Anxiety Depression Scale-was used for the assessment of depressive disorder and clinical definition of insulin resistance, requiring the presence of three or more of the following factors: triglycerides > 1.7 mmol/L; and high-density lipoprotein cholesterol < 1.0 mmol/L; blood pressure >/= 130/85 mm Hg; waist circumference > 102 cm in males and > 88 cm in females; fasting glucose 6.1-7.8 mmol/L. Depressive disorders prevailed significantly more in women than in men (39% and 26%, respectively), and prevalence of depression in subjects with metabolic syndrome of insulin resistance (by definition) was about four times higher than in subjects without depression. Depressive subjects had also higher heart rate, waist circumference, lower high-density lipoprotein cholesterol, higher triglycerides, and higher body mass index. Higher sympathetic nervous activity in insulin-resistant subjects with depression was indicated.

It is estimated that in the Asia-Pacific region, more than 5.2 million persons are suffering from familial hypercholesterolemia (FH). This means that more than half of the estimated world total of 10 million FH patients are living in this part of the world, of which the vast majority is not aware of their dangerous condition, let alone being adequately treated. Obviously, an intensive case-finding program to identify patients and subsequent clinical management are required to prevent premature cardiovascular disease and death caused by the consequences of inherited hypercholesterolemia. This article describes the current situation concerning FH and the initiatives and actions undertaken in Australia to contribute to actively identifying patients with FH in that country.

The clinical diagnosis of familial hypercholesterolemia (FH) in children is based on family history and laboratory findings. The best available value of low-density lipoprotein cholesterol (LDL-C) for the diagnosis of FH in children is >3.50 mmol/L (>135 mg/dL) when FH runs in the family. Levels below this concentration were only found in 4.3% of children that had a mutation in the LDL-receptor gene. In contrast, children with LDL-C equal to or above 3.50 mmol/L had 0.98 posttest probability of FH. Untreated FH carries a substantial burden of morbidity and mortality if left untreated or if inadequately treated. The guidelines of the American National Cholesterol Education Program suggested that drug treatment should be considered from the age of 10 years if LDL-C levels are greater than or equal to 4.9 mmol/L (190 mg/dL) or greater than or equal to 4.1 mmol/L (158 mg/dL) in the presence of other cardiovascular risk factors, including a positive family history of premature cardiovascular disease. Impaired flow mediated dilatation was more pronounced in FH children with a positive family history of premature cardiovascular disease. The currently prescribed diet is sometimes considered to be monotonous and can lead to problems with compliance. A reduction of the total intake fat and saturated fatty acids is important. Plant sterolesters should be evaluated in young FH children and can supplement drug and diet therapy, with an additional reduction of 10 to 15% of LDL-C. The use of resins leads to poor compliance, and statins are recommended for FH children and adolescents when drug treatment is indicated. Pravastatin, simvastatin, and atorvastatin decrease LDL-C 30 to 40% without serious adverse events and have a high degree of compliance.

A total of 119 different mutations in the low-density lipoprotein-receptor gene have so far been found to cause familial hypercholesterolemia (FH) among Norwegian patients. As of April 2003, 2390 patients from 959 unrelated families were provided with a molecular genetic diagnosis. Of these, 25.3% had xanthomas and 8.4% had xanthelasma. During the last 2-3 years, a systematic family-based program to identify close relatives of FH patients has been established. A total of 851 relatives of 188 index patients have undergone genetic testing. Four hundred seven people (47.9%) were affected, and 444 (52.1%) were unaffected. Only 41.5% of those affected were on lipid-lowering drugs, and only 6.1% had a value for total serum cholesterol below 193 mg/dL (5.0 mmol/L). A follow-up study was conducted in 146 of 407 affected relatives 6 months after genetic testing was performed. Of those already under treatment at the time of genetic testing, nonsignificant reductions of total serum cholesterol and low-density lipoprotein cholesterol of 3.2% and 7.1% were observed. Of those not under treatment who were aged 18 years and older, the corresponding reductions were 21.2% (p <.0001) and 30.0% (p <.0001), respectively. We conclude that molecular genetic methods represent a feasible and highly efficient tool in a family-based strategy to diagnose FH.

A case-finding program for the identification of patients with familial hypercholesterolemia (FH) has been established in Spain. The program is based on family investigation and molecular genetic testing for mutations in the low-density lipoprotein receptor gene. To assist this program, intensive research into the molecular basis of FH and genotype/phenotype relations is performed. To optimize DNA testing, a DNA-diagnostic platform has been constructed that is composed of systematic mutation screening by single-strand conformation polymorphism (SSCP) analysis, DNA-sequencing, Southern blotting, and the use of microarrays for high-throughput analysis. To date, 161 different mutations leading to inherited hypercholesterolemia have been identified in Spanish patients with FH. In addition, a patient organization was founded to ensure patient support and follow-up. To further facilitate FH case-finding and patient follow-up, we initiated the publication of a set of guidelines for diagnosis and clinical management of FH that can be applied internationally.

Uptake of cholesterol, mediated by the low-density lipoprotein (LDL)-receptor, plays a crucial role in lipoprotein metabolism. The LDL-receptor is responsible for the binding and subsequent cellular uptake of apolipoprotein B- and E-containing lipoproteins. To accomplish this, the receptor has to be transported from the site of synthesis, the membranes of the rough endoplasmatic reticulum (ER), through the Golgi apparatus, to its position on the surface of the cellular membrane. The translation of LDL-receptor messenger RNA into the polypeptide chain for the receptor protein takes place on the surface-bound ribosomes of the rough ER. Immature O-linked carbohydrate chains are attached to this integral precursor membrane protein. The molecular weight of the receptor at this stage is 120.000 d. The precursor-protein is transported from the rough ER to the Golgi apparatus, where the O-linked sugar chains are elongated until their final size is reached. The molecular weight has then increased to 160.000 d. The mature LDL-receptor is subsequently guided to the "coated pits" on the cell surface. These specialized areas of the cell membrane are rich in clathrin and interact with the LDL-receptor protein. Only here can the LDL-receptor bind LDL-particles. Within 3 to 5 minutes of its formation, the LDL-particle-receptor complex is internalized through endocytosis and is further metabolized through the receptor-mediated endocytosis pathway. Mutations in the gene coding for the LDL-receptor can interfere to a varying extent with all the different stages of the posttranslational processing, binding, uptake, and subsequent dissociation of the LDL-particle-LDL-receptor complex, but invariably the mutations lead to familial hypercholesterolemia. Thus, mutations in the LDL-receptor gene give rise to a substantially varying clinical expression of familial hypercholesterolemia.

Mutations in the low-density lipoprotein (LDL) receptor gene cause familial hypercholesterolemia. In homozygous familial hypercholesterolemia, both genes for the LDL- receptor are mutated and LDL levels are markedly elevated. High-density lipoprotein cholesterol concentration is often reduced and lipoprotein(a) levels are high when corrected for apolipoprotein(a) isoforms. Cutaneous and tendinous xanthomata develop in childhood and are the most common reason for initial presentation. The diagnosis can be confirmed by analysis of LDL-receptor genes or studies of LDL receptor function in cultured cells. Severe aortic and coronary atherosclerosis usually occurs within the first or second decades of life. Left ventricular outflow tract obstruction may be at the level of the aortic valve or the supravalvar aorta. Treatment for the hyperlipidemia is with plasmapheresis, high-dose statins, and ezetimibe. Liver transplantation reverses the metabolic defect but requires chronic immunosupression, and rejection may still occur. Liver transplantation is indicated if cardiac transplantation becomes necessary. Portocaval shunt may still play a role in patients with coronary artery disease who do not have access to plasmapheresis. Gene therapy is currently not practicable but is being actively developed.

Laboratory-based coronary heart disease risk assessment classically involves measurement of lipids and lipoproteins. In this review, information is provided on the methods commonly used in laboratories for the diagnosis of hyperlipidemia, including aspects of precision and accuracy. The latter, when fulfilled, allows the use of uniform reference values. Special attention is paid to the risk estimation using apolipoprotein B and lipoprotein(a) measurement. The overall aim of this review is to simplify the laboratory-based risk estimation for coronary heart disease and to provide help in interpreting the results for effective prevention and treatment of this complex disease.

Physicians should be properly informed of the clinical chemistry diagnostic potential for the diagnosis and classification of hyper- and dyslipidemias by laboratory determinations of lipids, lipoproteins, and apolipoproteins. New analytes are regularly found to be relevant for screening and risk estimation for coronary artery disease in vascular medicine. These analytes can be distinguished between parameters working on the long-term or working acutely. However, in times of restricted laboratory budgets, it is not always possible to add the new analyte to the routine diagnostic supply without having answered the question of whether the new analyte indeed adds to the chronic or acute risk estimation power presently available. This is relevant for homocysteine and for C-reactive protein (CRP). Both parameters appear to be interrelated to most common cardiovascular risk factors supposed to promote atherosclerosis and to ultimately provoke cardiovascular disease, and in fact are not independent. The latter certainly has added value in acute situations. With regard to the chronic risk estimators, it must be concluded that there is a multifactorial influence, with an important contribution made by social and lifestyle factors. This review draws attention to the multifactorial aspects of coronary heart disease, risk profiling using computer programs, socioeconomic factors, and implementation problems of interventions.