Effects of amlodipine and isosorbide dinitrate on exercise-induced and ambulatory ischemia in patients with chronic stable angina pectoris

This study was designed to compare once-daily administration of 5-10 mg amlodipine with two daily doses of 40 mg sustained-release isosorbide dinitrate in 59 patients with stable angina using a randomized, double-blind, crossover study design. Anginal episodes, nitroglycerin consumption, and possible adverse events were recorded in a diary. A maximal symptom-limited bicycle exercise test and 48-hour ambulatory ECG monitoring were performed at baseline and at the end of each 5-week period of therapy. Exercise time, time to angina, time to ST depression, and maximal ST depression were measured during exercise. During ambulatory monitoring, the number of ischemic episodes and the duration per hour of ST depression were assessed. Amlodipine significantly reduced anginal episodes (P < 0.001) when compared with isosorbide dinitrate. Furthermore, amlodipine prolonged time to ST depression (P < 0.001) and time to angina (P < 0.05) when compared with isosorbide dinitrate. The number and duration of ischemic episodes during ambulatory monitoring were significantly reduced with amlodipine when compared with baseline values (P < 0.05), whereas no differences were found between isosorbide dinitrate and baseline. Adverse events were reported more frequently with isosorbide dinitrate than with amlodipine (P < 0.02). Amlodipine appears to be more effective and tolerable than sustained-release isosorbide dinitrate as monotherapy for chronic stable angina.

Heterozygous lipoprotein lipase deficiency: frequency in the general population, effect on plasma lipid levels, and risk of ischemic heart disease

BACKGROUND

Patients with mutations on both alleles of the lipoprotein lipase gene resulting in complete lipoprotein lipase deficiency exhibit the chylomicronemia syndrome with severe hypertriglyceridemia and increased risk of pancreatitis and possibly of ischemic heart disease. This study examined frequency, lipid levels, and risk of ischemic heart disease for heterozygous carriers of lipoprotein lipase mutations known to cause the chylomicronemia syndrome in the homozygous state.

METHODS AND RESULTS

Two mutations were screened for in 9259 individuals in a general population sample and in 948 patients with verified ischemic heart disease. The percent frequencies of heterozygous individuals with the Gly188-->Glu and Ile194-->Thr substitutions in the general population were 0.06% (95% CI, 0.04% to 0.23%) and 0% (95% CI, 0.00% to 0.12%), respectively. The Gly188-->Glu substitution was associated with an increase in plasma triglycerides of 0.8+/-0.3 mmol/L (mean+/-SEM) and a decrease in plasma HDL cholesterol, apo A-I, and glucose levels of 0.45+/-0.07 mmol/L, 17+/-6 mg/dL, and 1.1+/-0.2 mmol/L, respectively. On multiple logistic regression analysis allowing for age, sex, plasma cholesterol, plasma lipoprotein (a), hypertension, diabetes mellitus, smoking, and body mass index, both plasma triglycerides and HDL cholesterol levels were independent predictors of ischemic heart disease. Finally, the Gly188-->Glu substitution was more common among patients with verified ischemic heart disease (percent frequency of heterozygous individuals, 0.32%) than among individuals from the general population (odds ratio, 4.9; 95% CI, 1.2 to 19.6). The effects of the Gly188-->Glu substitution were more pronounced than those of the common Asn291-->Ser substitution.

CONCLUSIONS

Heterozygous lipoprotein lipase deficiency due to the Gly188-->Glu substitution appears to increase plasma triglycerides and reduce HDL levels and may thereby predispose carriers to ischemic heart disease.

Report from the HLA class II typing by PCR-SSP Multicentre Study

Results from 360 HLA-DR and -DQ 'low-resolution' typings with polymerase chain reaction sequence-specific primers (PCR-SSP), performed by nine laboratories, were analysed for their overall utility in routinely defining the HLA-DR1-DR18, DR51-DR53 and DQ1-DQ9 specificities in less than 2.5 h. Thirty EDTA blood samples and 10 DNA samples were distributed and analysed by each laboratory. DNA was extracted using a rapid bromide salt extraction protocol. Complete HLA-DR and -DQ typings were performed, three by three, on pre-aliquoted 96-tube PCR trays. When compared with reference typing, 351/360 (98%) correct DR typings were obtained, whereas 320/360 (89%) of the DQ phenotypes were correctly assigned. The time for three complete HLA-DR and -DQ 'low-resolution' typings, including DNA extraction, ranged from 2.0 h to 2.3 h. Unfortunately, an unusually high level of PCR amplification failures was observed (3%), probably due to diffusion and a significant volume loss from some of the pre-aliquoted primer mixes. Consequently, only 52% of the typings were without any amplification failure, and 0-2 amplification failures where found in 88% of the PCR-SSP typings performed. The number of HLA-DR-DQ retypings needed was 7 and 8%, respectively, reflecting the low number of typings where allelic identification was directly affected by the relatively high level of amplification failures in this study. Thus, a 91-98% success rate of correctly identified HLA-DR and -DQ alleles could be maintained, even under suboptimal typing conditions.

ACE gene polymorphism: ischemic heart disease and longevity in 10,150 individuals. A case-referent and retrospective cohort study based on the Copenhagen City Heart Study

BACKGROUND

Homozygosity for the deletion allele (D) of the angiotensin-converting enzyme (ACE) gene insertion-deletion polymorphism has been suggested to be a potent risk factor for myocardial infarction. With one exception, the samples studied so far have been small and/or ethnically heterogeneous, and most investigators have studied men only.

METHODS AND RESULTS

We investigated the association between ACE genotype and myocardial infarction as well as other manifestations of ischemic heart disease for both women and men in a case-referent study (n = 10,150) as well as in a retrospective cohort study (n = 7263). The cohort was from the ethnically homogeneous Danish population. Case subjects were from the same geographic area and had ischemic heart disease. Irrespective of the assumed degree of relative penetrance of the D allele, the odds ratios were not significantly different from 1.0 (P > .05) for ischemic heart disease, severe stenosis on coronary angiography, or myocardial infarction. There was also no association between ACE genotype and phenotypic variation in recognized risk factors for ischemic heart disease. Finally, the relative frequency of the D allele did not change as a function of age in subjects aged from 20 to > or = 80 years.

CONCLUSIONS

In two large studies, a case-referent study and a retrospective cohort study in an ethnically homogeneous white population, there was no evidence for a statistically significant difference in the development of myocardial infarction or any other manifestations of ischemic heart disease between genotype classes of the ACE gene polymorphism in either women or men.

Frequency of HLA-B27 subtypes in a Danish population and in Danish patients with ankylosing spondylitis

Polymerase chain reaction in combination with sequence-specific oligonucleotide probes were used to analyze nine HLA-B27 subtypes among 51 healthy HLA-B27 positive Danish blood donors and 30 Danish HLA-B27 positive patients with ankylosing spondylitis (AS). In the group of healthy Danes we found two subtypes, B*2705 (90.2%) and B*2702 (9.8%), however, among the AS patients only the B*2705 subtype was detected. We did not find a significant evidence for associations between AS and a particular HLA-B27 subtype in a Danish population.

A common substitution (Asn291Ser) in lipoprotein lipase is associated with increased risk of ischemic heart disease

Lipoprotein lipase degrades triglycerides in plasma and as a byproduct produces HDL particles. Genetic variation in lipoprotein lipase may therefore affect cardiovascular risk. We tested 9,214 men and women from a general population sample and 948 patients with ischemic heart disease for the Asn291Ser substitution in lipoprotein lipase. The allele frequency in the general population was 0.024 and 0.026 for women and men, respectively. In comparison with noncarriers, female heterozygous probands had increased plasma triglycerides (delta = 0.23 mmol/liter), while HDL cholesterol was reduced in both female and male carriers (delta = 0.18 mmol/liter and delta = 0.11 mmol/liter, respectively). A similar phenotype was found in six homozygous carriers. On multiple logistic regression analysis, plasma triglycerides and HDL cholesterol were independent predictors of ischemic heart disease in both genders. On univariate analysis, odds ratios for ischemic heart disease in probands were 1.89 in women (95% CI: 1.19-3.01) and 0.90 in men (95% CI: 0.62-1.31), and on multivariate analysis were 1.98 in women (95% CI: 1.11-3.53) and 1.02 in men (95% CI: 0.65-1.60). This study demonstrates that a single common mutation in the lipoprotein lipase gene is associated with elevated plasma triglycerides and reduced HDL cholesterol levels, whereby carriers, in particular women, seem to be predisposed to ischemic heart disease. It cannot be excluded, however, that male carriers of this substitution may represent a subset of low-HDL individuals without raised triglycerides not predisposed to ischemic heart disease.

Frequency of platelet-specific alloantigens in a Danish population

This study reports the first data on gene frequencies of platelet alloantigens HPA-1, HPA-2, HPA-3, HPA-4 and HPA-5 in a population of unrelated Danish blood donors using PCR-techniques. The observed gene frequencies fit the Hardy-Weinberg equilibrium, and the calculated phenotype frequencies are similar to those obtained in other Caucasian populations: HPA-1a and -1b occur in 96.6% and 30.3% of 557 unrelated respectively. HPA-2a and -2b in 99.4% and 15.9% of 163 tested, HPA-3a and -3b in 88.3% and 63.2% of 163 tested, HPA-4a and -4b in 100% and 0% of 131 tested, and finally HPA-5a and -5b in 100% and 15.7% of 427 tested. It is a major technical improvement to use PCR techniques for genomic typing of HPA. Not only is it possible to perform HPA typings in severely thrombocytopenic patient and on amniotic fluid cells of the fetus of alloimmunized mothers, but it must be expected that accuracy of the HPA typing will increase considerably, as has been the case with genomic HLA class II typing. Finally, use of PCR technique combined with allele-specific primers is suitable for accurate large scale typing of platelet donors, which may be useful in special clinical settings.

Insulin-resistant glucose metabolism in patients with microvascular angina--syndrome X

Studies in patients with microvascular angina (MA) or the cardiologic syndrome X have shown a hyperinsulinemic response to an oral glucose challenge, suggesting insulin resistance and a role for increased serum insulin in coronary microvascular dysfunction. The aim of the present study was to examine whether patients with MA are insulin-resistant. Nine patients with MA and seven control subjects were studied. All were sedentary and glucose-tolerant. Coronary arteriography was normal in all participants, and exercise-induced coronary ischemia was demonstrated in all MA patients. A euglycemic, hyperinsulinemic clamp was performed in combination with indirect calorimetry. Biopsy of vastus lateralis muscle was taken in the basal state and after 4 hours of euglycemia and hyperinsulinemia (2 mU.kg-1.min-1). The fasting level of "true" serum insulin was significantly higher (43 +/- 6 v 22 +/- 3 pmol/L, P < .02) and the rate of insulin-stimulated glucose disposal to peripheral tissues was lower in patients with MA (13.4 +/- 1.0 v 18.2 +/- 1.4 mg.kg fat-free mass [FFM]-1.min-1, P < .02) due to a decrease in nonoxidative glucose metabolism (8.4 +/- 0.9 v 12.5 +/- 1.3 mg.kg FFM-1.min-1, P < .02). No difference was found in glucose or lipid oxidation rates between the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)

[Prognosis of acute myocardial infarction after introduction of thrombolytic therapy]

The present study describes the use of intravenous thrombolytic therapy, the in-hospital and the long-term mortality in a cohort of 1881 consecutive patients with confirmed myocardial infarction. Thirty-two percent received thrombolytic therapy. Common reasons for not administering thrombolytic therapy were contraindications, diagnostic problems and late hospital admission. The total in-hospital mortality was 14% among patients treated with, and 27% among those treated without thrombolytic therapy (p < 0.001). The mortality among all patients after 48 months of follow-up was 50%. Advanced age, previous myocardial infarction and a higher Killip class on admission were independent predictors of an adverse outcome. In conclusion, in an unselected population with confirmed myocardial infarction the long-term prognosis continues to be dubious, despite the advances in coronary care including intravenous thrombolytic therapy.

Genomic cloning of the human histo-blood group ABO locus

A P1 phage clone containing the near complete protein coding region of the human histo-blood group ABO gene locus was isolated and characterized. The insert was estimated at approximately 41 kp, and an approximately 20 kbp BamHI fragment contained the near complete coding region as evaluated by Southern blot analysis. Intron/exon boundaries were determined and the coding region was found to span at least seven exons. In situ hybridization to metaphase chromosomes confirmed the predicted localization to 9q34.

Short-term effects of captopril on exercise tolerance in patients with chronic stable angina pectoris and normal left ventricular function

A double-blind, placebo-controlled, crossover study was carried out to evaluate the short-term effects of captopril on exercise tolerance in 18 normotensive patients with chronic stable angina pectoris and normal left ventricular function. Captopril 25 mg (or placebo) was given twice, i.e. in the evening (10 p.m.) and the following morning (8 a.m.), prior to a maximal symptom-limited bicycle exercise test (11 a.m.). Captopril reduced the systolic and diastolic blood pressures at rest (p < 0.01) without causing any reflex tachycardia. The time to onset of S-T depression was prolonged (p < 0.05), and the maximal S-T depression was reduced (p < 0.02). No differences were found between captopril and placebo in total exercise duration or time to onset of angina. The effects of captopril on exercise-induced ischemia were demonstrated most clearly in patients who responded with a greater than 10 mm Hg fall in the resting systolic blood pressure. In conclusion, this study suggests that captopril has anti-ischemic properties, which may be of importance in the treatment of patients with chronic stable angina and normal left ventricular function. These beneficial effects probably relate to a reduction in afterload and myocardial wall stress and therefore a reduction in myocardial oxygen demand.

Evaluation of histo-blood group ABO genotyping in a Danish population: frequency of a novel O allele defined as O2

Traditional blood group ABO serology is based on immunoreactivity with the carbohydrate determinants A, B and H antigens. Recent advances at the DNA level of the ABO genes have provided a molecular genetic model for the ABO polymorphism. This genetic model has to date only been tested on a limited basis. The present study was initiated to evaluate the universality of the proposed genetic model on a larger group of serologically defined ABO phenotypes. Three hundred healthy Danish blood donors were analysed (A:50, B:50, AB:50, O:150) by PCR amplification followed by diagnostic restriction enzyme cutting. In all cases A, B, and AB at least one allele of correctly predicted status was found. However, in O phenotype individuals, 11 out of 150 carried one allele discordant to the proposed genetic model. This novel O allele (3.7% allele frequency) was further characterized by diagnostic restriction enzyme analysis in two positions divergent between A and B alleles and by DNA sequencing of the two major exons. The novel O allele is termed O2 as it typed as B in nucleotide position 526 and as A in positions 703, 796, and 803, in contrast to the most predominant O allele termed O1, which types as A in all 4 positions. The structural defect in the O2 allele appears to be an additional substitution at nucleotide position 802. The results clearly demonstrate that with the addition of the two distinctly different O alleles, O1, O2, the previously proposed molecular genetic basis of the ABO polymorphism is quite valid.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of atenolol and diltiazem on exercise tolerance and ambulatory ischaemia

Twenty-five normotensive patients with stable angina, angiographically documented coronary disease and normal left ventricular function were randomized to a crossover study comparing atenolol 100 mg x 1, sustained-release diltiazem 120 mg x 2, and their combination. A maximal symptom limited bicycle exercise test and a 24-h ambulatory electrocardiographic (ECG) monitoring were performed at the end of each treatment period. Exercise duration was increased equally in the different treatment groups. Time to onset of 1-mm ST-segment depression was longer with atenolol (P < 0.02) and combination therapy (P < 0.01) than with diltiazem. The maximal ST-segment depression was decreased with atenolol (P < 0.05) and combination therapy (P < 0.02), whereas, time to onset of angina was prolonged only with combination therapy (P < 0.03). The number of ischaemic episodes during ambulatory monitoring was lower with atenolol and combination therapy than with diltiazem (P < 0.01). The difference between atenolol and diltiazem was mainly due to lower ischaemic activity with atenolol between 06:00 h and 12:00 h (P < 0.05). Anginal frequency (P < 0.01) and nitroglycerin consumption (P < 0.05) were lower with combination therapy than with monotherapy. Thus, while comparable effects were achieved on clinical variables, atenolol appeared to be more effective than diltiazem, reducing myocardial ischaemia during exercise and ambulatory monitoring. With combination therapy, both clinical and electrocardiograph signs of ischaemia were improved.

[A randomized study of streptokinase and recombinant tissue plasminogen activator, with and without heparin, in patients with acute myocardial infarction. The results of GISSI-2/International tPA/SK Mortality Trial]

A total of 20,981 patients in 14 countries with suspected myocardial infarction (AMI) admitted within six hours from onset of symptoms, were randomized to recombinant tissue plasminogen activator (tPA) (100 mg over 3 hours) or streptokinase (SK) (1.5 MU over one hour). Half of the patients were also randomly allocated to subcutaneous heparin (12,500 U twice daily). The hospital mortality was similar with SK and tPA (8.5% vs. 8.9%), and similar with and without heparin (85.5% vs. 8.9%). Likewise, no differences were found in the number of cardiac complications. More strokes occurred with tPA (1.3%) than with SK (0.9%), while more major bleeds were seen with SK (0.9%) than with tPA (0.6%). More major hemorrhages were also observed with heparin (1.0%) than without heparin (0.5%), whereas, heparin did not affect the incidence of stroke or reinfarction. Fewer allergic reactions were observed with tPA (0.2%) than with SK (1.7%). It is concluded that tPA and SK are equally effective and safe for use, and should be recommended for treatment in patients with an AMI of less than six hours duration.

Increased frequency of HLA-DRw14b(w6)-associated RFLP in Greenlanders of Eskimo origin

HLA-DR typing by the restriction fragment length polymorphism (RFLP) technique of 42 Greenlanders living in northern Jutland, Denmark, revealed a phenotype frequency of 33.3% for HLA-DRw14b(w6), which is significantly different from the frequency of 0.0% observed among 98 Danes of Caucasian origin. When comparing the two populations, the frequency of other HLA-DRB allogenotypes show insignificant variations. Since HLA-DRw14b(w6) is carried by approximately one-third of the Greenlanders tested, this allogenotype may serve as a useful marker in further anthropological and immunogenetic studies.