Serum homocysteine, folate, vitamin B12 levels and arterial stiffness in diabetic patients: which of them is really important in atherogenesis?

AIM: Hyperhomocystinaemia is associated with macro- and microangiopathic diabetic complications. However, the role of homocysteine (Hcy), serum folate, and vitamin B12 level in the development of premature vascular damage in type 2 diabetic patients is not clear. The present study was designed to assess the relationship between total Hcy, folate, and vitamin B12 levels and arterial stiffness, an early marker of generalized atherosclerosis. METHODS: As many as 86 subjects with type 2 diabetes mellitus were studied. All participants were evaluated for glucose, HbA(1C), lipid profile, hs-CRP, endothelin, Hcy, vitamin B12, and folate. Pulse wave velocity (PWV) and augmentation index (AI) were performed as a non-invasive recording and computer analysis of the two artery sites pressure waveform using SphygmoCor (version 7.1, AtCor Medical, Sydney, Australia). RESULTS: Hcy was significantly positively associated with age, serum creatinine, and vitamin B12 levels. No association between Hcy and folate was observed. The Hcy concentration was significantly positively associated with PWV (r = 0.540, p < 0.0001) and AI (r = 0.390, p < 0.0001). In a general linear model of PWV, Hcy emerged as an independent predictor of PWV even after controlling for age, creatinine, vitamin B12, and folate levels. In a multiple linear regression analysis, the association between Hcy and arterial stiffness was independent of traditional cardiovascular risk factors. Vitamin B12 levels were significantly inversely associated with tHcy (r = - 0.263, p = 0.015) and marginally associated with PWV(r = - 0.212, p = 0.052). Significant associations between folate levels and PWV were not detected. CONCLUSIONS: The results lend support to the hypothesis that elevated Hcy may have a key role in the development of atherogenesis in diabetic patients. Additionally, vitamin B12 is significantly associated with tHcy concentrations and is identified as a marginally independent correlate of PWV in diabetic patients in the absence of folate deficiency.

Comparative analysis between dextran sulfate adsorption and direct adsorption of lipoproteins in their capability to reduce erythrocyte adhesiveness/aggregation in the peripheral blood.

The purpose of this study was to compare the degree of erythrocyte adhesiveness/aggregation (EAA) reduction of two low-density lipoprotein (LDL) apheretic procedures, namely direct adsorption of lipoproteins (DALI) and dextran sulfate adsorption (DSA). A significant (P < 0.001) reduction of EAA was noted in six hypercholesterolemic patients who underwent a total of 40 apheretic sessions and no difference was noted in the degree of EAA reduction by the two techniques. Thus. being a real-time and point-of-care test, the erythrocyte adhesiveness/aggregation test can be applied in relevant situations of acute ischemia, where therapeutic LDL apheresis could improve the hemorheology of individuals with increased concentrations of cholesterol and inflammatory sensitive proteins.

Significant dominance of fibrinogen over immunoglobulins, C-reactive protein, cholesterol and triglycerides in maintaining increased red blood cell adhesiveness/aggregation in the peripheral venous blood: a model in hypercholesterolaemic patients.

BACKGROUND: It is not clear what is the relative importance of fibrinogen, immunoglobulins, highly sensitive C-reactive protein (hs-CRP), cholesterol and triglyceride concentrations on the appearance of aggregated red blood cells in the peripheral blood. DESIGN: Six hypercholesterolaemic patients undergoing regular LDL apheresis that were examined repeatedly before and following the procedure. RESULTS: We determined the degree of erythrocyte adhesiveness/aggregation in relation to the concentration of the above-mentioned macromolecules in 80 samples. In a linear logistic regression the respective R2 values for fibrinogen, total cholesterol, triglycerides, hs-CRP, IgG, IgM and IgA were 0.45 (P<0.0001), 0.2 (P<0.0001), 0.02 (P=0.02), 0.001 (P=NS) and 0.002 (P=NS), respectively. We further analyzed the potential of ApoA, ApoB and Lpa to participate in red cell adhesiveness/aggregation and found them to be not significant. CONCLUSIONS: In a milieu of adhesive macromolecules, lipids and inflammation-sensitive proteins including fibrinogen, total cholesterol, triglycerides, hs-CRP and immunoglobins G, M and A, fibrinogen has a dominant role in maintaining the red blood cell adhesiveness/aggregation in the peripheral venous blood. These findings are relevant for the research directed at finding new apheretic modalities to reduce the degree of red blood cell adhesiveness/aggregation in the peripheral blood.

Insulin resistance in obesity: body-weight or energy balance?

Weight reduction is recommended for the treatment of subjects with insulin resistance (IR) syndrome; however, the relative importance of the decrease in body fat or the negative energy balance achieved during a hypo-energetic diet in the improvement of this metabolic syndrome is still debated. Therefore, we undertook to study their relative impact on amelioration of the metabolic abnormalities associated with IR in obese subjects. Twelve obese subjects (six males and six females, mean+/-s.d. body mass index 36.1+/-4.7 kg/m(2)) aged 38-57 years were investigated. During the first phase they were fed a hypo-energetic diet for 6 weeks (week 0-6). During the second phase, lasting 4 weeks (week 6-10) they consumed an iso-energetic diet. During the third phase (week 10-16) the subjects were put again on a hypo-energetic diet. Insulin sensitivity (SI) was assessed by an insulin-enhanced, frequently sampled i.v. glucose tolerance test with minimal model analysis. All subjects reduced weight during both hypo-energetic periods: 5.49+/-0.75 and 2.32+/-0.37%, means+/-s.e.m., P<0.005, week 0-6 and 10-16 respectively. One-third of this loss was achieved within the first week of each period. SI increased by 353+/-121 and 147+/-38% (P<0.005), means+/-s.e.m., at the end of both hypo-energetic periods (week 6 vs 0 and 16 vs 10 respectively). Two-thirds of this improvement were observed within the first week of each period (week 1 vs 0 and 11 vs 10 respectively). During the iso-energetic weight-maintaining period (week 10 vs 6), SI decreased by 43.5+/-7.9% (P<0.002). Serum levels of leptin and triglyceride followed a similar pattern, but to a lesser extent. It may be concluded that negative energy balance is more effective when compared with maintaining a stable lower weight in achieving an improvement in the metabolic parameters of the IR syndrome.

Weight gain and insulin resistance during nicotine replacement therapy.

BACKGROUND: Although the cessation of smoking reduces the increased risk for ischemic heart disease, it is associated with marked weight gain and presumably insulin resistance, both of which heighten the risk of coronary heart disease. HYPOTHESIS: We investigated the isolated effect of nicotine on body weight and insulin resistance during smoking cessation. METHODS: Eleven healthy, middle-aged heavy smokers were studied. Insulin sensitivity was assessed by an insulin-enhanced, frequently sampled intravenous glucose tolerance test with minimal model analysis. The subjects were studied at baseline (last day of smoking) (phase 1), at the end of the 6-week nicotine replacement program (phase 2), and after 8 weeks without smoking or nicotine replacement (phase 3). RESULTS: The subjects started to gain weight during nicotine replacement (phase 2) (0.3 +/- 0.2 kg/week, mean +/- standard deviation) and continued to do so at a steady rate after nicotine replacement was stopped (0.2 +/- 0.2 kg/week) (p = 0.3). Insulin sensitivity decreased by 14 +/- 2.6% during nicotine replacement but increased by 16 +/- 5.1% (compared with phase 2) during phase 3, even though the weight gain continued (p = 0.047; 95% confidence interval: 0.05-5.73). CONCLUSIONS: Smoking cessation is associated with weight gain and improvement in insulin resistance. Nicotine is the main ingredient in cigarette smoke causing insulin resistance, but the withdrawal of another, unknown ingredient in cigarette smoke is responsible for the weight gain associated with smoking cessation.

Pregnancy outcome in familial homozygous hypercholesterolemic females treated with long-term plasma exchange.

BACKGROUND: The use of plasma-exchange therapy has increased the longevity of patients with homozygous familial hypercholesterolemia (HFH), and pregnancy in affected women is expected to become more common. We describe the clinical course, feasibility and risks of repeated pregnancies in patients with HFH treated by long-term plasma exchange. METHODS: We followed the clinical course of five pregnancies in two HFH patients, with attention to the effect of repeated plasma exchange on maternal and fetal status; specifically, lipid profile, hemodynamics, and uteroplacental circulation on Doppler flow study. RESULTS: Increasing the frequency of plasma-exchange therapy prevented the extreme serum cholesterol elevation that occurs in pregnant HFH patients and was associated with a significant improvement in uteroplacental circulation. In four pregnancies the clinical course was uneventful, ending in normal deliveries of full-term infants with heterozygous familial hypercholesterolemia. The third pregnancy of one of the patients had to be terminated owing to the development of hypotension and syncope during plasma exchange because of severe aortic stenosis. CONCLUSIONS: Repeated pregnancies in HFH patients treated by long-term plasma exchange are feasible but may be associated with untoward effects, especially hemodynamic compromise. The frequency of plasma exchange therapy should be increased to prevent marked hypercholesterolemia and its possible deleterious effect on maternal and fetal status. Cardiac evaluation with close hemodynamic monitoring are needed during pregnancy to detect complications of the cardiac valvular lesion and the coronary atherosclerosis that are associated with HFH.

Effects of hypocholesterolemic dietary and drug therapy on measures of dysphoric emotions.

The question of whether hypocholesterolemic treatment is associated with increased mortality due to suicide, violence and car accidents is controversial and of great importance. We investigated the effect of hypocholesterolemic dietary and drug therapy on dysphoric emotions. Twenty-five hypocholesterolemic men were started on a 3-month dietary modification plan; those who showed unsatisfactory cholesterol reduction were given, in addition, a hypocholesterolemic drug for up to 1 year. Lipid profile and change in dysphoric emotions were measured. During the whole period, a negative correlation was found between cholesterol level and depression. During the dietary period, a significant improvement in depression and guilt with no change in lipid profile was noted. Drug therapy significantly reduced cholesterol levels, with a trend toward increased depression (after 3 months) and a significant increase in aggression and guilt (after 1 year). We conclude that changes in dysphoric emotions occurring during hypocholesterolemic therapy cannot be completely explained by the changes in cholesterol levels.

The effect of lovastatin on early restenosis.

The effect of lovastatin given before percutaneous coronary angioplasty (PTCA) on early restenosis was investigated in men with mild to moderate hypercholesterolemia. Thirty-four hypercholesterolemic patients (serum LDL cholesterol 130-200 mg/dL) undergoing their first PTCA completed a 6-month prospective, double-blind, placebo-controlled trial. Eighteen received lovastatin 20 mg/day (Lo group) and 16 placebo (P1 group), beginning 10 to 21 days before PTCA. All underwent a thallium-201 quantitative exercise test 5 to 7 days after PTCA. Endpoints for restenosis were either 50% narrowing of the dilated artery on coronary angiography, performed in symptomatic patients or, in asymptomatic patients, the appearance of newly developed reversible filling defects in the vascular territory of the dilated artery on a second thallium scan done 6 months after PTCA. The hypocholesterolemic change observed in the Lo group was not accompanied by a reduction in early restenosis risk. The authors conclude that effective hypocholesterolemic therapy before PTCA does not affect early restenosis rate in men with mild to moderate hypercholesterolemia.

Efficacy and safety of pravastatin once daily in primary moderate hypercholesterolemia: the Israeli experience.

Seventy-seven hypercholesterolemic patients participated in a 26-week, multicenter, randomized, double-blind, placebo-controlled study that investigated the efficacy and safety of pravastatin therapy. All patients had primary moderate hypercholesterolemia (total cholesterol 200-300 mg/dl, at the end of a 6-week dietary run-in period) and two additional coronary risk factors. Pravastatin, 20-40 mg/day given at bedtime, reduced total cholesterol by 19-22%, LDL-cholesterol by 24-30%, triglycerides by 10-30% and increased HDL-cholesterol by 9-13%. The drug caused mild elevation in alanine aminotransferase and aspartate aminotransferase. Almost all these elevations were within normal limits and no patient was clinically symptomatic. No other significant differences were observed between the pravastatin and the placebo-treated groups with regard to other adverse effects and to patient compliance and withdrawal. It is concluded that pravastatin has a beneficial effect on the lipid profile and that the drug is safe and well tolerated.

A missense mutation in the low density lipoprotein receptor gene causes familial hypercholesterolemia in Sephardic Jews.

Familial hypercholesterolemia (FH) is an autosomal dominant disease caused by mutations in the low density lipoprotein (LDL) receptor gene. Here, we characterize an LDL receptor mutation that is associated with a distinct haplotype and that causes FH in the Jewish Sephardic population originating from Safed, a town in northern Israel. The mutation was found in eight FH families originating from this community comprising 10% of heterozygote FH index cases screened in Israel. The mutation was not found in four additional FH heterozygotes whose hypercholesterolemia co-segregated with an identical LDL receptor gene haplotype. A guanine to cytosine substitution results in a missense mutation (asp147 to his) in the fourth repeat of the binding domain encoded by exon 4 of the LDL receptor gene. The mutant receptor protein was synthesized in cultured cells as a 120 kDa precursor form that failed to undergo normal processing to a mature cell surface form. Most of the receptor precursors were degraded in the endoplasmic reticulum. The small number of mutant receptors on the cell surface were unable to bind LDL or beta very low density lipoprotein. The abnormal behavior of the mutant receptor was reproduced by site-directed mutagenesis and expression of the mutant protein in CHO cells. The mutation can be diagnosed by allele-specific oligonucleotide hybridization of polymerase chain reaction amplified DNA from FH patients.

Coronary risk factors in children of parents with premature coronary artery disease.

In order to assess the value of family history of premature coronary artery disease as a criterion for coronary risk factor screening, a group of 53 children with such a family history was selected. We determined various coronary risk factors in these children in comparison to 33 controls. Statistically significant differences were observed in apoprotein concentrations but not in concentrations of lipids, lipoproteins or glucose, or in blood pressure or body mass index. The ratio between apoprotein B and apoprotein AI was the best discriminator between the two groups. The predictive value of family history is more reliable for detecting abnormal apoprotein ratio than for detection of hypercholesterolemia. We conclude that if abnormal apoprotein levels during childhood are found to be a valued predictor of premature coronary artery disease, then family history of premature coronary artery disease can be used to select children for determination and assessment of their coronary risk.

Big platelets in hyperlipidemic patients.

Both "big" platelets and hyperlipidemia are associated with increased coronary risk. This study was undertaken to search for a possible effect of various hypolipidemic drugs on big platelets. The percentage of big platelets, assessed microscopically, was measured in 66 patients who had hyperlipidemia of various types. Twenty-seven patients with hypertriglyceridemia were randomly selected to receive either fish oil or placebo in a crossover study. Another group of 39 patients with hypercholesterolemia, among them 13 with heterozygous familial hypercholesterolemia (FH), received lovastatin. The pretreatment level of big platelets was elevated, and similar in all groups: 23.3 +/- 12% versus 22 +/- 9%, in the fish oil versus placebo group, 19.1 +/- 6.3% versus 24 +/- 11% in the FH versus non-FH primary hypercholesterolemia group (reference value, 6.8 +/- 3.5%). After treatment, despite the improvement in lipoprotein profile, the percentage of big platelets did not change. The relationship between lipid reduction and big platelets is thus questionable, and necessitates further study.

Lovastatin therapy in heterozygous familial hypercholesterolaemic patients: effect on blood rheology and fibrinogen levels.

Thirteen heterozygous familial hypercholesterolaemic patients were treated with lovastatin for 1 year, and were investigated for the effect on lipid profile, blood rheology and fibrinogen levels. A significant dose-dependent reduction in serum levels of total and LDL-cholesterol, Apo B and the ratio of total cholesterol to HDL-cholesterol was noted. Improvement in red blood cell filterability and an increase in fibrinogen levels were also observed. We conclude that the hypocholesterolaemic effect of lovastatin in familial hypercholesterolaemia is accompanied by changes in blood rheology. While some of these haemorheological changes may be considered beneficial, others may be regarded as unfavourable. The net effect of lovastatin therapy on the coronary risk of familial hypercholesterolaemic patients warrants further investigation.

Lovastatin therapy in hypercholesterolemia: effect on fibrinogen, hemorrheologic parameters, platelet activity, and red blood cell morphology.

The effect of lovastatin therapy on blood rheology was investigated in 26 hypercholesterolemic patients. Treatment with lovastatin was associated with a significant improvement in whole blood filtration time and a tendency toward normalization in red blood cell morphology. A significant increase was observed in fibrinogen level, in ADP-induced platelet aggregation, in the percentage of "big" platelets, and in platelet count. The viscosity of whole blood and plasma and the percentage of aggregated platelets did not change significantly. The cause for these hemorrheologic changes and their role in influencing the coronary risk of lovastatin-treated hypercholesterolemic patients should be further investigated.