Mutation analysis in a small cohort of New Zealand patients originating from the United Kingdom demonstrates genetic heterogeneity in familial hypercholesterolemia.

Familial hypercholesterolemia (FH) and familial defective apolipoprotein B-100 (FDB) are relatively common lipid disorders caused by mutations in the low-density lipoprotein receptor (LDLR) and apolipoprotein B (apo B) genes, respectively. Molecular analysis at these loci was performed in eight New Zealand subjects with clinical features of heterozygous FH. Utilization of an in vitro lymphocyte receptor assay demonstrated normal receptor function in four patients, three of whom screened positive for the founder-type apo B mutation, R3500Q, causing FDB. Four patients with reduced LDLR function, consistent with heterozygous FH, revealed three previously documented mutations in exons 3 (W66X), 6 (C292Y) and 7 (G322S) of the LDLR gene and, a novel 2-bp deletion (TC or CT) after nucleotide 1204 (or 1205) in exon 9. The remaining patient was found to be FH/FDB negative after extensive mutation screening using both denaturing gradient gel electrophoresis and heteroduplex-single strand conformation polymorphism analysis. Haplotype analysis at the LDLR and apo B loci finally excluded the likelihood that mutations in these two genes underlie the FH phenotype in the molecularly uncharacterized New Zealand family originating from the United Kingdom. This family represents a valuable source of material for future genetic dissection of autosomal dominant hypercholesterolemia (ADH), shown to be a heterogeneous disease through molecular analysis.

Will acarbose improve the metabolic abnormalities of insulin-resistant type 2 diabetes mellitus?

Individuals with type 2 diabetes mellitus (n = 105; age 36-71 years) on diet therapy alone, and with quite good glycaemic control (mean HbA1c approximately 7.0%) were randomized to receive acarbose (100 mg three times daily) or placebo for 16 weeks, and changes in clinical and metabolic parameters indicative of Syndrome X were monitored. Fasting levels of glucose, glycosylated haemoglobin (HbA1c), true insulin, proinsulin, fibrinogen and lipids were measured four times weekly, and glucose, insulin, proinsulin and triglyceride responses to a standardized 1.6 MJ breakfast were determined at 0, 1 and 2 h post meal. Analysis was on an intention-to-treat basis. Fasting levels of glucose (P < 0.0001), triglycerides (P = 0.03) and HbA1c (P = 0.003) were reduced by acarbose over the 16 weeks of treatment. The mean change in HbA1c from week 0 to 16 differed by 0.4% (P = 0.003) between the two groups. Insulin (P = 0.06), proinsulin (P = 0.07) and glucose (P < 0.0001) responses to the standard meal were reduced. These data show that acarbose reduces fasting glucose and triglyceride levels, lowers HbA1c and limits the glycaemic and insulin response to food in individuals with type 2 diabetes mellitus with Syndrome X. Pharmacological agents that improve the metabolic environment and reduce insulin resistance have the potential to limit the progression of atherogenesis associated with type 2 diabetes mellitus.

Fluvastatin for dyslipoproteinemia, with or without concomitant chronic renal insufficiency.

Renal insufficiency is frequently associated with both quantitative and qualitative abnormalities in lipid and hemorheologic profiles. Although this may lead to increased risk of cardiovascular disease, a number of studies have also shown dyslipidemia to be a significant risk factor for the progression of renal insufficiency in human chronic renal disease. This double-blind, placebo-controlled trial aimed to assess the effect of fluvastatin, a synthetic 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, on these parameters in dyslipidemic patients with or without chronic renal insufficiency. After a 6-week placebo run-in, 42 patients who had been previously stratified into 2 groups on the basis of creatinine clearance levels (0.5-1.0 mL/sec or > 1.0-1.5 mL/sec) were randomized to treatment with fluvastatin (40 mg daily) or matching placebo. Significant differences (on analysis of variance with repeated measures) were seen between fluvastatin and placebo treatment groups for changes in total cholesterol (-15% vs 1%, respectively; p < 0.001), low density lipoprotein cholesterol (LDL-C; -21% vs -5%; p < 0.001), very low density lipoprotein cholesterol (-14% vs 14%; p = 0.017), very low density lipoprotein triglycerides (-1% vs 29%; p = 0.014) and total triglycerides (-7% vs 24%; p < 0.001). These effects on cholesterol levels were reflected in a significant decrease in apolipoprotein B levels with fluvastatin therapy (p < 0.001). Apolipoprotein A-I levels increased (p = 0.054) despite no significant change in the levels of high density lipoprotein cholesterol. Response to therapy did not differ between the 2 renal function groups for any of the lipid, lipoprotein, and apolipoprotein variables. Hemorheologic parameters were not altered with fluvastatin therapy, regardless of renal function.(ABSTRACT TRUNCATED AT 250 WORDS)

Screening for mutations in exon 4 of the LDL receptor gene: identification of a new deletion mutation.

DNA from 14 unrelated New Zealand familial hypercholesterolaemia (FH) heterozygotes, originating from the United Kingdom, was screened for mutations in exon 4 of the low density lipoprotein receptor (LDLR) gene. One patient was heterozygous for mutation D206E, which was initially identified in South Africa. The chromosomal background of this mutant allele was compatible with that described previously in Afrikaner and English patients, suggesting that this mutation originated in the United Kingdom. The 2 bp deletion in codon 206 and mutations D154N and D200G, previously reported in English FH patients, were not detected in this sample. In one of the patients, however, a new deletion of 7 bp was identified after nucleotide 581 (or 582) in exon 4 of the LDLR gene.

Dexfenfluramine reduces cardiovascular risk factors.

This study investigated the potential for dexfenfluramine to improve biochemical and clinical risk factors for cardiovascular disease, in obese dyslipidaemic individuals. Dexfenfluramine, the dextro isomer of fenfluramine, has been shown to aid weight reduction and lower blood lipids in normal subjects, and to improve glucose tolerance and insulin sensitivity in subjects with diabetes mellitus. Twenty-nine overweight (mean weight 83.3 +/- 11.3 kg), hyperlipidaemic (mean total cholesterol 7.3 +/- 1.2 mol/l) subjects participated in a 12-week randomized double-blind parallel study of dexfenfluramine versus placebo. After an eight-week dietary run-in phase, subjects were randomised to treatment with either dexfenfluramine or placebo for 12 weeks. During the run-in, energy intakes fell in both groups (5.5% for dexfenfluramine, 5% for placebo, no significant difference between groups). Dietary composition improved, fat as a percentage of energy decreased (14%, P < 0.001, for dexfenfluramine; 11.7%, P < 0.05, for placebo), and carbohydrate increased (8.5%, P < 0.05, for dexfenfluramine; 5.6%, not significant, for placebo). During the treatment period, energy intakes in the dexfenfluramine group were further reduced by 7.5%, whereas there was no change in the placebo group (P = 0.02 between dexfenfluramine and placebo groups); however, nutrient composition remained constant for both groups. Side-effects were formally reported by 40% of subjects during the initial four weeks' treatment with dexfenfluramine with three subjects withdrawing from the study. Side-effects were largely resolved by week 4. Both groups lost weight similarly during the run-in but there were no significant changes in any biochemical parameters.(ABSTRACT TRUNCATED AT 250 WORDS)

Treating hypercholesterolaemia with HMG CoA reductase inhibitors: a direct comparison of simvastatin and pravastatin.

BACKGROUND: Simvastatin and pravastatin are both competitive inhibitors of the rate limiting enzyme for cholesterol biosynthesis (HMG CoA) reductase, but data from individual clinical trials suggest significant differences in potency for cholesterol reduction between the two drugs. AIM: To assess any differences in efficacy and safety between simvastatin and pravastatin in a direct, comparative study. METHODS: A double-blind, double-dummy, randomised study design was used, involving 48 patients with primary hypercholesterolaemia. Following a 6 week placebo baseline period, patients were randomly allocated to treatment with either simvastatin or pravastatin, commencing at a dose of 10 mg daily. The dose levels were titrated up to the recommended maximum effective dose of 40 mg daily at 6 weekly intervals if LDL cholesterol levels remained > or = 3.4 mmol/L. After 18 weeks of therapy, all patients were transferred to simvastatin therapy for a further 6 weeks, continuing at their week 18 dose level. Patients complied with a standard lipid lowering diet (containing < 30% of energy as total fat) throughout the study period. RESULTS: Over the 18 week direct comparison of the two drugs, there was a significant difference (p < 0.001) in response between simvastatin and pravastatin for reduction in levels of total cholesterol (32% vs 21% respectively), LDL cholesterol (38% vs 27%) and apolipoprotein B levels (34% vs 23%). No significant difference in drug effect was seen for the small reduction in levels of apolipoprotein AI (5% vs 6% respectively), nor for the increased levels of apolipoprotein AII (14% vs 11%) and HDL cholesterol (11% vs 7%). Lp(a) levels remained unchanged. When pravastatin was replaced with simvastatin for the final 6 weeks of the study in the 23 patients initially randomised to pravastatin, there were further reductions (p < 0.01) in total and LDL cholesterol, and apolipoprotein B. These results establish the advantage of simvastatin over pravastatin in terms of efficacy, for the treatment of primary hypercholesterolaemia.

Lipid, lipoprotein and apolipoprotein distributions in an elderly New Zealand population.

The aim of this study was to determine the lipid, lipoprotein and apolipoprotein distribution in an ambulant elderly New Zealand population, and to consider the association between these and other variables (including body mass index, diabetes mellitus, and smoking history) with the prevalence of manifest macrovascular disease in a cross-section analysis. The population sample was randomly selected from the age/sex register of a large urban medical centre in Christchurch, New Zealand. A total of 369 subjects (participation rate 69%) aged 65 years and older were screened for manifest macrovascular disease, diabetes mellitus, smoking status, height and body weight. Levels of plasma total cholesterol, triglycerides, HDL cholesterol, apolipoproteins AI and B, glucose, glycated haemoglobin and fibrinogen were measured. Three way analysis of variance (ANOVA) was used to compare continuous variables across age/sex/macrovascular disease groups. Females had significantly higher levels of total and HDL cholesterol, apolipoproteins AI and B than males. Body mass index showed a significant decrease with increasing age. Macrovascular disease was manifest in 24% of males, and in 26% of females. No direct correlation was seen between any of the measured continuous variables and the presence of macrovascular disease, except for fibrinogen (P < 0.05). No significant association was seen between macrovascular disease and smoking status, nor with a diagnosis of diabetes. In females, the frequency of macrovascular disease was significantly higher amongst those with low (< 1.00 mmol/L) levels of HDL.

HMG-CoA reductase inhibitor use in the aged. A review of clinical experience.

While the benefit of cholesterol-lowering in the elderly has yet to be proven in clinical trials, individuals at high risk of coronary events who otherwise enjoy a good quality of life, should not be denied cholesterol-lowering therapy on the basis of age alone. Moreover, hypolipidaemic drugs are already extensively used in the aged. The HMG-CoA reductase inhibitors lovastatin, simvastatin and pravastatin are potent well tolerated hypolipidaemic therapies in young subjects. Although there have been few studies on their use in elderly subjects, the available data suggest the efficacy and safety of HMG-CoA reductase inhibitors in similar to that established for younger age groups.

Prevalence of diabetes mellitus in an ambulant elderly New Zealand population.

The prevalence of diabetes mellitus (both known and previously undiagnosed) was studied in a population sample, predominantly Caucasoid and resident in the community with an age/sex distribution representative of the New Zealand population aged 65 + years, using WHO criteria. The population sample was randomly selected from the age/sex register of a large urban medical centre in Christchurch, New Zealand. Three hundred and sixty-nine subjects (participation rate 69.4%) were screened by casual glucose and glycated haemoglobin measurement, followed by oral glucose tolerance testing (OGTT) if one or both were elevated. The minimum prevalence rate of diabetes in the study sample was 17.2 +/- 3.3% in men and 12.5 +/- 2.2% in women (since not all patients underwent OGTT). The rate was only significantly higher in men than women in the 70-74 year age group (P less than 0.01). The combined age-adjusted prevalence rates for the New Zealand elderly are estimated to be 9.9% known diabetes, 5.0% previously undiagnosed, with the total prevalence rate 14.9%. Newly diagnosed subjects had a significantly higher body mass index than known diabetic or non-diabetic subjects (P less than 0.01). Eighty-two percent of newly diagnosed subjects had visited their general practitioner at least once during the previous 6 months. Measurement of glycated haemoglobin had a greater positive predictive value than casual blood glucose in the detection of new cases. There was no difference in frequency of attendance with general practitioners or in hospital admission rates between non-diabetic patients, or those with known or newly diagnosed diabetes. This study suggests that diabetes mellitus may be a prevalent disorder amongst the New Zealand elderly.

Plasma non-cholesterol sterols in patients with non-insulin dependent diabetes mellitus.

Plasma plant sterol concentrations (an index of cholesterol absorption efficiency) and plasma lathosterol concentration (an index of cholesterol synthesis rate) were measured in 52 patients with non-insulin dependent diabetes mellitus (NIDDM) and 36 non-diabetic controls. Plasma plant sterol concentrations were significantly (P less than 0.01) lower in diabetic patients (campesterol: men -36%, women -48%; betasitosterol: men -35%, women -42%). Fasting serum insulin levels were inversely correlated with plasma plant sterol concentrations in diabetic patients (campesterol: r = -0.347, P = 0.012; betasitosterol: r = -0.345, P = 0.012) and in non-diabetic men (campesterol: r = -0.578, P = 0.039; betasitosterol: r = -0.702, P = 0.008). Serum insulin levels were also correlated significantly with plasma lathosterol concentration in diabetic patients (r = 0.295, P = 0.034). The results of this study suggest that absorption of plant sterols and possibly cholesterol from the diet may be reduced in hyperinsulinemic diabetics.

Simvastatin and side effects.

OBJECT: to investigate the symptomatic and biochemical side effect profile of simvastatin (a new cholesterol lowering drug) following routine use in a specialist hospital outpatient clinic. METHODS: all patients (n = 110) newly commenced on simvastatin at the lipid disorders clinic at the Princess Margaret Hospital in the first ten months of prescription availability were asked to complete a side effects questionnaire and biochemical evaluation at six months of therapy. RESULTS: 76.4% of patients reported experiencing no side effects with 8% of patients spontaneously reporting feeling better since commencing therapy. Nineteen point one percent of patients reported experiencing symptoms they attributed to simvastatin but had continued therapy, while a further 4.5% of patients had withdrawn from therapy because of side effects. The most frequently reported side effects were muscle ache (13.6%), and gastrointestinal symptoms (4.5%). No abnormalities in biochemical safety tests occurred. CONCLUSIONS: the rate of side effects reported with prescription use exceeds that previously encountered in clinical trials. Since simvastatin is considered effective and well tolerated it is likely to receive wide acceptance in the management of high risk hypercholesterolaemic patients. However, this study indicates the need for continued physician awareness of the main symptoms and their frequency amongst those treated with simvastatin.

Treatment of primary hypercholesterolaemia with simvastatin. New Zealand multicentre evaluation.

OBJECTIVE: To assess the efficacy of simvastatin in a large patient cohort. DESIGN: In an open multicentre study, after a four week placebo phase, patients were treated with simvastatin for 24 weeks; a subgroup continued therapy for a further 24 weeks. Efficacy of simvastatin (a) with prolonged use over three years, and (b) in combination with bezafibrate was assessed in an open single site study. SETTING: Lipid or cardiology specialist hospital outpatient clinics. PATIENTS: For the open multicentre study, 228 patients with primary hypercholesterolaemia (total cholesterol level greater than 6.5 mmol/L) were recruited, of whom 224 met entry criteria and completed the study. Forty-seven of these patients continued therapy for one year. In the open single site study, 22 patients (with low density lipoprotein [LDL] cholesterol levels greater than 4.3 mmol/L) participated in studies of long term use (n = 9) or of combined therapy (n = 13). INTERVENTION: Therapy in the open multicentre study began with 10 mg of simvastatin per day, doubling to 20 mg after six weeks and then 40 mg after 12 weeks of therapy if total cholesterol levels persisted above 5.2 mmol/L. In the study of long term use, simvastatin (40 mg daily) was taken continuously over three years. In the study of combination therapy, bezafibrate (600 mg daily) was taken in addition to simvastatin (40 mg daily) for 10 months. MAIN OUTCOME MEASURES: Plasma lipid and lipoprotein concentrations. RESULTS: In the multicentre study, total plasma cholesterol levels were reduced by 32.8% from 9.11 +/- 1.84 (in mmol/L, mean +/- SD) to 6.12 +/- 1.25 (P less than 0.001), and LDL cholesterol levels by 41.4% from 6.90 +/- 1.92 to 4.04 +/- 0.31 (P less than 0.001). The effect of therapy was sustained in those patients continuing therapy to 48 weeks. The study of long term use found no significant attenuation of effect over three years of monotherapy. Combined simvastatin/bezafibrate therapy reduced the LDL cholesterol concentration by a further 19.9% (P less than 0.001) from levels achieved on simvastatin alone. CONCLUSIONS: Simvastatin is an effective, well tolerated lipid lowering drug, without significant attenuation of effect with prolonged use. Simvastatin plus bezafibrate appears to be a potentially useful drug combination.

Oat bran and cholesterol reduction: evidence against specific effect.

Most placebo-controlled studies testing the hypo-cholesterolaemic action of oat bran have compared high fibre against low fibre diets. To determine whether oat bran had greater cholesterol-lowering action than another source of fibre (wheat bran) we compared the effect of breads of similar total fibre content containing either oat bran or additional wheat bran. Twelve hyperlipidaemic subjects (38-66 years) were stabilised on lipid-lowering diets for at least three months prior to the study. Subjects were given each type of bread for four-week periods in a single-blind, cross-over design. Cholesterol, triglyceride and LDL-cholesterol levels did not change significantly during the oat and wheat bread periods. HDL-cholesterol rose equivalently but only to a just significant level during the oat bran diet. Body weights, lipids and lipoprotein parameters were not significantly different between the two diet periods. Both diet treatments lowered serum cholesterol approximately 4%. We conclude that this oat bran bread consumed as part of a lipid-correcting diet did not influence lipoproteins to any greater extent than wheat bread of similar total fibre content.

Simvastatin (MK 733): an effective treatment for hypercholesterolemia.

This study describes the efficacy of the drug simvastatin. It is likely to be the first HMG CoA reductase inhibitor in Australia and New Zealand available for the treatment of hyperlipidemia. Twenty-four patients, 12 men and 12 women with primary hypercholesterolemia were randomly allocated to treatment by cholestyramine (eight patients) or to simvastatin (16 patients) for a 12-week period. With simvastatin, total cholesterol levels decreased by 37.5% from a baseline mean of 10.33 mmol/L to 6.4 mmol/L after 12 weeks. Low density lipoprotein (LDL) cholesterol concentration decreased by 48.2% from 8.40 mmol/L to 4.39 mmol/L. These effects were better than observed for cholestyramine alone where cholesterol and LDL-cholesterol reductions were 24.9% and 33.1% respectively. Thirteen patients, however, did not achieve target LDL levels of 3.62 mmol/L, or below, and therefore were treated with a combination of cholestyramine and simvastatin, resulting in a decrease of total cholesterol and LDL-cholesterol by 45.5% and 53.5% of baseline values studied over an eight-week period. No major clinical side-effects were encountered. One patient appeared to have had a change in colour vision at the end of the study at 20 weeks, without loss of visual acuity.

Treatment of hyperlipidaemia with acipimox.

In an open, uncontrolled study, the hypolipidaemic effect of acipimox was evaluated in 34 patients with Types IIa, IIb, IV or V hyperlipidaemia. Doses of 250 mg twice daily or 250 mg 3-times daily were maintained over a 12-week treatment period. The reduction in total plasma cholesterol levels was small and not statistically significant; however, significant increases in high density lipoproteins were achieved. Triglyceride levels were significantly lowered in patients with Type IV hyperlipidaemia. Acipimox was well tolerated by patients and no biochemical or haematological changes were noted. Considerable resolution in tubo-eruptive xanthomata was observed in 1 patient with Type V hyperlipidaemia.

Apolipoprotein E phenotypes in hyperlipidaemic patients and their implications for treatment.

Apolipoprotein E phenotypes were determined on 417 consecutive lipid clinic patients using an isoelectric focussing technique. Of the 15 patients with phenotype E2/2, 13 (3.1%) had type III hyperlipoproteinaemia and 2 obese identical twins had type V. A further 20 patients (4.8%) had similar plasma and lipoprotein lipid levels but were E2 heterozygotes (14 E3/2 and 6 E4/2). They displayed a widened pre-beta-band almost confluent with the beta-band rather than the broad beta-band shown in classical E2/2 type III patients. In view of the similarities between these heterozygotes and the classical homozygous (E2/2) type III patients and their occurrence in the same families we suggest the nomenclature homozygous and heterozygous type III. In a subsequent comparison between 30 E2/2, 22 E3/2 and 8 E4/2 type III individuals the only significant difference in plasma and lipoprotein lipid parameters was a lower VLDL cholesterol to triglyceride ratio of 0.85 in E3/2 patients than that of 1.24 in E2/2 patients (P less than 0.01). Both homozygous and heterozygous patients showed premature ischaemic heart disease and both responded dramatically and similarly to treatment with clofibrate. These observations indicate that apo E phenotyping is worthwhile in all patients with combined hyperlipidaemia and that homozygous and heterozygous type III hyperlipoproteinaemia is not uncommon.