Haemodynamic effects of intravenously administered prenalterol in patients with severe heart failure

The acute haemodynamic effects of prenalterol 75-225 micrograms/kg i.v. were studied at rest and during exercise in the supine position in 12 patients with chronic congestive heart failure secondary to myocardial infarction (6 pts), chronic valvular disease with valvular replacement (4 pts), ischaemic cardiomyopathy (1 pt) and post myocarditis (1 pt). In 5 of the 6 AMI patients the effect of prenalterol on myocardial oxygen consumption at rest was measured. Pulmonary artery end-diastolic pressure decreased significantly from 17 to 10 mm Hg at rest and from 31 to 21 mm Hg during exercise. Resting heart rate increased from 78 to 90 at rest but was unchanged during exercise. MVO2 in the 5 patients was unchanged or lower in 4 patients and increased in one in whom angina developed after prenalterol. In general, dyspnoea and angina during exercise were less pronounced after prenalterol. The calculated triple product was lower after prenalterol, especially during exercise, indicating lower myocardial oxygen consumption and probably less myocardial ischaemia.

Effects of prenalterol administered orally in patients with congestive heart failure

A single-blind study of prenalterol 20-200 mg daily in a slow-release tablet preparation and a placebo was performed in 15 patients with moderate to severe congestive heart failure (NYHA II-IV) to evaluate the haemodynamic and clinical effects of oral prenalterol. Non-invasive parameters in the measurement of cardiac output, stroke volume, pre-ejection period index (PEPI), PEP/LVET ratio, ejection fraction and mean Vcf were significantly improved, indicating beneficial effects of prenalterol on cardiac contractility. Systolic blood pressure, heart rate and rate-pressure product were slightly increased at rest but were considerably lower during exercise. Arrhythmogenecity was not seen in the patients studied. Subjective improvement was noted in the majority of patients as evidenced by a decreased frequency of dyspnoea, fatigue and angina. Unwanted effects, such as palpitations and transmitted arm pulsations, were transient and disappeared with dose adjustment, while the inotropic effect of the medication was maintained. The clinical response appeared to be sustained for up to 2 weeks of treatment, indicating non-development of tachyphylaxis.

Relationship between the enzymatically estimated infarct size and clinical findings in acute myocardial infarction

In 580 patients with a definite myocardial infarction (MI) and no previous MI, the enzymatically estimated infarct size was related to the clinical course including various complications. In all patients, heat-stable lactate dehydrogenase activity (EC 1.1.1.27, LD) was analyzed every 12 hours for 48-108 hours and in a subgroup (n = 170) creatine kinase activity (EC 2.7.3.2, CK) and creatinine kinase subunit B (CK B) were analyzed every 6 hours for 48 hours. The highest recorded enzyme activity was used as a rough estimate of infarct size. A positive correlation was found between serum enzyme activity and most of the clinical variables studied, such as incidence of congestive heart failure, treatment with furosemide, incidence of hypotension, cardiogenic shock, pericarditis, post myocardial infarction syndrome, AV block III, and the duration of hospitalization. We conclude that the enzymatically estimated infarct size determined by heat-stable LD, CK and CK B closely reflects the severity of the infarction.

Acute intervention with metoprolol in myocardial infarction

Studies in experimental and clinical myocardial infarction support the idea that sympathetic activity and myocardial noradrenaline release play a significant role in the development of myocardial ischemic damage. Betablockade has been shown to limit infarct size and lower the incidence of ventricular fibrillation in experimental models. Betablockade to patients (pts) with acute myocardial infarction (AMI) has been shown to reduce ischemia reflected as reduction of ischemic chest pain, decrease ST-segment elevation and increase lactate extraction. Whether this treatment in the clinical situation can prevent development of infarction, reduce infarct size and early mortality in man remains to be proven. In Gøteborg a double-blind study on metoprolol and placebo was started four and a half years ago. Inclusion of pts. in the study has been terminated and survival data will be available on May 1, 1981. 1395 pts. were included of whom 800 developed AMI. Metoprolol 15 mg was given IV followed by a total daily dose of 200 mg/day. The tolerance for betablockade was generally good. Analysis of serum enzyme estimations of maximal LD I + II showed a significant reduction by metoprolol when the treatment was given within 12 hours of onset of pain. In a subgroup consisting of 103 pts. with AMI metoprolol had no clearcut effects on the ventricular arrhythmias during the first 24 hours in hospital. The betablockade resulted in a 15% reduction in heart rate. The main objective of this study, the mortality during three months of blind treatment will be published late in 1981.

Effects on mortality during five years after early intervention with metoprolol in suspected acute myocardial infarction

This study reports the mortality over a 5-year-period determined a double-blind trial, which evaluated the effect of early intervention with metoprolol in suspected acute myocardial infarction. In all, there were 1,395 randomized patients, 698 and 697 of whom were allocated to metoprolol 200 mg daily and placebo treatments, respectively, for the first 3 months. Thereafter, the two groups were treated in a similar fashion implying beta-blockade to a majority. Within the first 3 months, mortality in the metoprolol group was 5.7% versus 8.9% of the placebo group (p = 0.02). This difference persisted after 2 years (metoprolol 13.2%; placebo 17.2%; p = 0.04). Over a 5-year-period, 24.2% of the patients who originally were allocated to metoprolol had died as compared to 25.7% of those originally allocated to placebo (p greater than 0.2). Among patients in whom treatment started early (less than or equal to 8 hours after onset of pain = the median delay time), enzyme activities in the metoprolol group was lower (p = 0.03) than in the placebo group. Mortality during the first 2 years among these patients treated early was lower in the metoprolol (11.8%) than in the placebo group (17.3%; p = 0.04). Corresponding figures after 5 years were 22.0% and 25.3%, respectively (p greater than 0.2). Among patients in whom treatment started later than 8 hours onset of pain, there was neither any difference in enzyme activity nor in mortality after 2 and 5 years. It can be concluded that early treatment with metoprolol in suspected acute myocardial infarction reduced mortality during the first 3 months compared with placebo. The difference persisted after 2 years. However, 5 years after randomization, no significant difference in mortality was observed between the two treatment groups.

Possible adrenergic effects on heart protein metabolism

It is known that the heart will adapt to actual demand by increasing or decreasing its size through different mechanisms. In this presentation, the possible role of catecholamines in regulating heart protein synthesis and developing cardiac hypertrophy and cardiomyopathy is discussed. Injecting animals with catecholamines has been found to induce cardiac hypertrophy. In vitro perfusion of rat heart in the presence of catecholamines has been found to induce a time-dependent and dose-dependent stimulation of amino acid transport and incorporation into proteins. Acute haemodynamic effects of catecholamines increase cardiac performance while long-term treatment seems to cause depression of cardiac function, especially during ischaemic conditions. Chronic beta-blockade in patients with primary congestive cardiomyopathy improved both cardiac function and clinical condition in more than half the patients. Furthermore, a beneficial effect on survival was also found, when compared with a matched control group. It is hypothesised that catecholamines may play a role in developing cardiac hypertrophy as well as congestive cardiomyopathy.

Mortality and morbidity during a five-year follow-up of diabetics with myocardial infarction

In 787 patients with acute myocardial infarction originally participating in the Göteborg Metoprolol Trial, mortality and morbidity during 5 years' follow-up were assessed and related to whether patients had diabetes mellitus. Diabetes occurred in 78 patients (10%). Patients with diabetes had a different risk factor pattern, including higher age, higher occurrence of angina pectoris and hypertension, whereas smoking habits did not differ. In the early phase (hospitalization), patients with diabetes had a higher mortality (12% versus 8%), required more treatment for heart failure and stayed longer in hospital. Other morbidity aspects, such as severity of pain, occurrence of severe supraventricular and ventricular arrhythmias, high-degree AV-block and infarct size did not differ. During 5 years' follow-up mortality rate in patients with diabetes mellitus was 55% as compared with 30% among patients with no diabetes (p less than 0.001). Reinfarction rate during 5 years was 42% in diabetics versus 25% in non-diabetics (p less than 0.001). In a multivariate analysis, taking into account the differences in risk factor pattern, diabetes turned out to be an independent determinant for long-term mortality and reinfarction (p less than 0.001). We conclude that patients with diabetes mellitus, developing acute myocardial infarction, is a group with particularly high risk of death and reinfarction. Interventions aiming at its reduction have priority.

Relationship between enzymatically estimated infarct size and short- and long-term survival after acute myocardial infarction

In 585 patients with acute myocardial infarction (AMI) and no previous MI the maximal activity of serum heat-stable lactate dehydrogenase (LD) (EC 1.1.1.27) activity was related to 1-year and 2-year mortality rates. All patients participated in a double-blind trial with metoprolol during the first three months after an AMI. Thereafter both groups were treated in a similar way. A strong relationship was found between LD maximum activity and the in-hospital prognosis (p less than 0.001), the 1-year survival rate (p less than 0.001) and the 2-year survival rate (p less than 0.001). When the patients who were alive after primary hospitalization were analyzed as a separate group, the relationship between LD maximum activity and 1-year and 2-year survival rates remained (p less than 0.001). In a subsample of 171 patients the maximal activity of creatine kinase (CK) (EC 2.7.3.2) and CK subunit B did not correlate either with in-hospital, 1-year or 2-year survival rates. We conclude that, when a sufficiently large number of patients are investigated, there is a strong relationship between serum enzyme maximum activity and short- and long-term survival.

Tolerability to treatment with metoprolol in acute myocardial infarction in relation to age

A double-blind trial with the beta 1-selective blocker metoprolol in suspected acute myocardial infarction and during 3 months' follow-up included 1395 patients, aged 40-74 years, 698 on metoprolol and 697 on placebo. In order to further evaluate the tolerability to beta-blockade in the elderly, the total series was divided into 2 groups according to median age (61 years) and into quartiles, the lowest quartile (40-57 years) being compared with the highest (67-74 years). The decrease in heart rate and systolic blood pressure after intravenous metoprolol in the acute phase was similar in the elderly and the younger patients. Hypotension was observed more often in the metoprolol-treated than in the placebo-treated younger patients, while no difference was observed in the elderly. Bradycardia was observed more often in the metoprolol group in both age groups, while there was no difference regarding the incidence of congestive heart failure in either the younger or in the elderly patients. The effect on mortality, serious ventricular arrhythmias and chest pain seemed to be similar in different age groups. From the present series we conclude that hemodynamic reactions and tolerability to beta-blockade can be expected to be similar in elderly and younger patients.

Hemodynamic effects of the cardioselective beta-blocking agent metoprolol in acute myocardial infarction. A 24-hour catheterization study

Hemodynamic changes were studied in ten patients with uncomplicated transmural myocardial infection during 24 hours on beta-blockade. The cardioselective beta-adrenergic blocking drug metoprolol was injected (15 mg i.v.) within the first 24 hours after onset of chest pain and was followed by oral therapy (25-50 mg at 6-hour intervals). There was a decrease in heart rate, systolic BP, and cardiac output, which was most marked after the injection. The stroke volume and diastolic BP for the whole group of patients remained unchanged. The pulmonary artery end diastolic pressure did not change significantly after the injection but a continuous fall was obtained in three out of four patients with initially elevated values. The preejection period, measured from the ECG and carotid pressure curve, as initially short and was prolonged in all patients after administration of the beta-blocking drug. It is concluded that the cardioselective beta-blocking drug metoprolol may be used in selected patients in the acute phase of myocardial infarction without danger of hemodynamic deterioration during the first 24 hours of therapy. The selection of patients can be based on clinical criteria. In this study signs of left heart failure, hypotension, poor peripheral circulation, bradycardia, and AV block were regarded as contraindications.

Heart failure and statins—Why do we need a clinical trial?

The effect of statins to reduce mortality and morbidity in primary and secondary prevention as well as in acute coronary syndrome is well established. Recent data show that pleiotropic effects might also have direct effects on the myocardial cell. However, in chronic heart failure the outcome is inversely related to LDL-plasma concentrations and other pleiotropic effects might impair mitochondrial function. Since there are no safety data on the use of statins in chronic heart failure, a controlled randomized and placebo-controlled trial is urgently needed.

A multicentre, randomized, double-blind, placebo-controlled, 1-year study of bupropion SR for smoking cessation

BACKGROUND

Bupropion sustained release (bupropion SR) has been shown to increase smoking cessation success rates in the US studies.

OBJECTIVE

To determine whether bupropion SR, in combination with counselling, is effective for smoking cessation in a multi-country study.

METHODS

This randomized, double-blind, placebo-controlled trial enrolled 707 smokers. A total of 527 received bupropion SR 300 mg daily for 7 weeks and 180 received placebo. A total of 11 clinic visits and 10 telephone contacts were scheduled, during the course of 1 year. Seven-week and 12-month abstinence rates were the study outcomes.

RESULTS

Both continuous and weekly point prevalence smoking abstinence rates were significantly higher in the bupropion SR group compared with placebo. The continuous abstinence rate from weeks 4 to 7 was 46% in the bupropion SR group compared with 23% in the placebo group [odds ratio (OR) = 2.82; 95% confidence interval (CI) 1.89-4.28; P < 0.001). At month 12, the continuous abstinence rates were 21% for the bupropion SR group and 11% for the placebo group (OR = 2.19; 95% CI 1.29-3.86, P = 0.002). For most nicotine-withdrawal symptoms small changes were measured. Adverse events were higher for the bupropion SR group compared with placebo (insomnia 24% vs. 15%; dry mouth 13% vs. 5%).

CONCLUSION

Bupropion SR in combination with counselling increased the abstinence rate compared with placebo, and was well tolerated.

Different responses to dobutamine in the presence of carvedilol or metoprolol in patients with chronic heart failure

OBJECTIVE

To determine whether patients with congestive heart failure on different beta adrenoreceptor blocking drugs have similar haemodynamic responses to dobutamine.

DESIGN

Single centre, single blind, randomised, two period crossover study comparing carvedilol with metoprolol CR/XL.

PATIENTS

Ten patients with stable chronic congestive heart failure (ejection fraction < 40%) on chronic treatment with metoprolol CR/XL.

METHODS

Patients were treated with carvedilol or metoprolol CR/XL (target dose 50 mg twice daily and 200 mg once daily, respectively) for eight weeks. Stress echocardiography was undertaken at the end of each maintenance period, using dobutamine 5 and 15 microg/kg/min.

RESULTS

No significant haemodynamic differences were seen at rest on the two treatments. There was a more pronounced increase in heart rate and cardiac output during dobutamine infusion when the patients were on metoprolol than when they were on carvedilol. Mean arterial pressure increased significantly when the patients were on carvedilol, and cardiac output increased during low dose dobutamine, without further change during high dose dobutamine. During the dobutamine infusion, there was no significant difference in ejection fraction between carvedilol and metoprolol treatment.

CONCLUSIONS

Patients with congestive heart failure on a non-selective beta adrenoreceptor blocker or beta1 selective blocker responded differently to the inotropic drug dobutamine: the beta1 blockade caused by metoprolol could be counteracted by dobutamine, whereas with carvedilol a low dose of dobutamine increased cardiac output, and a higher dose of dobutamine caused a pressor effect. These findings may be clinically relevant when choosing an inotropic drug.

The chemical composition of interstellar molecular clouds

Relative abundances for molecules observed by radio astronomical techniques have been determined for several interstellar regions with differing physical properties.

Challenges of subgroup analyses in multinational clinical trials: experiences from the MERIT-HF trial

BACKGROUND

International placebo-controlled survival trials (Metoprolol Controlled-Release Randomised Intervention Trial in Heart Failure [MERIT-HF], Cardiac Insufficiency Bisoprolol Study [CIBIS-II], and Carvedilol Prospective Randomized Cumulative Survival trial [COPERNICUS]) evaluating the effects of b-blockade in patients with heart failure have all demonstrated highly significant positive effects on total mortality as well as total mortality plus all-cause hospitalization. Also, the analysis of the US Carvedilol Program indicated an effect on these end points. Although none of these trials are large enough to provide definitive results in any particular subgroup, it is natural for physicians to examine the consistency of results across various subgroups or risk groups. Our purpose was to examine both predefined and post hoc subgroups in the MERIT-HF trial to provide guidance as to whether any subgroup is at increased risk, despite an overall strongly positive effect, and to discuss the difficulties and limitations in conducting such subgroup analyses.

METHODS

The study was conducted at 313 clinical sites in 16 randomization regions across 14 countries, with a total of 3991 patients. Total mortality (first primary end point) and total mortality plus all-cause hospitalization (second primary end point) were analyzed on a time to first event. The first secondary end point was total mortality plus hospitalization for heart failure.

RESULTS

Overall, MERIT-HF demonstrated a hazard ratio of 0.66 for total mortality and 0.81 for mortality plus all-cause hospitalization. The hazard ratio of the first secondary end point of mortality plus hospitalization for heart failure was 0.69. The results were remarkably consistent for both primary outcomes and the first secondary outcome across all predefined subgroups as well as for nearly all post hoc subgroups. The results of the post hoc US subgroup showed a mortality hazard ratio of 1.05. However, the US results regarding both the second primary combined outcome of total mortality plus all-cause hospitalization and of the first secondary combined outcome of total mortality plus heart failure hospitalization were in concordance with the overall results of MERIT-HF. Tests of country by treatment interaction (14 countries) revealed a nonsignificant P value of.22 for total mortality. The mortality hazard ratio for US patients in New York Heart Association (NYHA) class III/IV was 0.80, and it was 2.24 for patients in NYHA class II, which is not consistent with causality by biologic gradient. We have not been able to identify any confounding factor in baseline characteristics, baseline treatment, or treatment during follow-up that could account for any treatment by country interaction. Thus we attribute the US subgroup mortality hazard ratio to be due to chance.

CONCLUSIONS

Just as we must be extremely cautious in overinterpreting positive effects in subgroups, even those that are predefined, we must also be cautious in focusing on subgroups with an apparent neutral or negative trend. We should examine subgroups to obtain a general sense of consistency, which is clearly the case in MERIT-HF. We should expect some variation of the treatment effect around the overall estimate as we examine a large number of subgroups because of small sample size in subgroups and chance. Thus the best estimate of the treatment effect on total mortality for any subgroup is the estimate of the hazard ratio for the overall trial.

Effect of smoking reduction and cessation on cardiovascular risk factors

This open study examined the effect of smoking reduction and smoking cessation on established cardiovascular risk factors. Fifty-eight healthy adult smokers (smoking >or=15 cigarettes/day for at least 3 years) were provided with nicotine nasal spray (to be used ad libitum) and asked to stop smoking. The primary goal during the first 8 weeks, however, was to reduce their daily smoking by at least 50%. Subjects were then followed for another 8 weeks; at this point, 33 participants had successfully stopped smoking. Cardiovascular risk factors including fibrinogen, hemoglobin, hematocrit, triglycerides, and cholesterol were measured at baseline and at 9 and 17 weeks. After 8 weeks of smoking reduction, the mean number of cigarettes smoked per day had decreased from 21.5 +/- 0.6 (baseline) to 10.8 +/- 0.6 (p < 0.001). This was accompanied by significant improvements in fibrinogen (from 2.9 +/- 0.1 g/l at baseline to 2.6 +/- 0.1 g/l, p = 0.011), white blood cells (from 7.0 +/- 0.4 to 6.2 +/- 0.3 x 10(9)/l, p = 0.005) and the high-density/low-density lipoprotein (HDL/LDL) ratio (0.33 +/- 0.03 to 0.37 +/- 0.03, p < 0.005). Following 8 weeks of abstinence from smoking, the mean white blood cell count was further reduced (to 6.1 +/- 0.3 x 10(9)/l, p = 0.026 vs. baseline) and there were also significant improvements in HDL (from 1.16 +/- 0.06 mmol/l at baseline to 1.32 +/- 0.06, p < 0.001) and LDL (from 3.78 +/- 0.16 mmol/l at baseline to 3.52 +/- 0.17, p = 0.015). In conclusion, 8 weeks of smoking reduction resulted in clinically significant improvements in established cardiovascular risk factors. These improvements were even greater after an additional period of abstinence from smoking.

MERIT-HF mortality and morbidity data

This survival study was designed to address whether beta-1-blockade utilizing metoprolol CR/XL (controlled release/extended release) once daily added to standard therapy reduces mortality and morbidity in patients with decreased ejection fraction and symptoms of heart failure. Enrolled in a double-blind randomized study were 3991 patients with chronic heart failure in NYHA functional class II-IV and ejection fraction < or = 0.40 stabilized on optimal standard therapy. Randomization was preceded by a 2-week single blind placebo run-in period. The study medication was uptitrated during 8 weeks starting with 12.5 mg (NYHA functional class III-IV) or 25 mg once daily (NYHA functional class II). The target dose was 200 mg once daily. The primary endpoints were all-cause mortality and combined all-cause mortality and hospitalization (time to first event) and other objectives were cause-specific data on hospitalization, NYHA functional class and quality of life. Mean follow-up time was 1 year. All-cause mortality was reduced in the metoprolol CR/XL group compared with the placebo group, 145 versus 217 deaths, 7.2% per patient year of follow-up versus 11.0% with a relative risk of 0.66 (95% CI 0.53-0.81, nominal p = 0.00009, p adjusted for interim analysis = 0.0062). This effect was consistent across all predefined subgroups. Sudden deaths were fewer in the metoprolol group (79 versus 132 deaths), RR 0.59 (p = 0.0002). Also deaths from worsening heart failure were fewer in the metoprolol group (30 versus 58 deaths), RR 0.51 (p = 0.0023). The combined endpoint total mortality or all-cause hospitalizations was also reduced by metoprolol (641 versus 767 events), RR 0.81 (p = 0.00012). Total mortality or hospitalizations due to worsening heart failure was also reduced (311 versus 439 events), RR 0.69 (p < 0.00001). The number of hospitalizations due to worsening heart failure (317 versus 451, p < 0.00001) and days in hospital due to worsening heart failure (3401 versus 5303 days, p < 0.00001) were also reduced by metoprolol. There was also an improvement in NYHA functional class, assessed by the physicians as well as the McMaster Overall Treatment Evaluation questionnaire (OTE), assessed by the patients (p = 0.028 and p = 0.089, respectively). Permanent early discontinuation was 13.9% in the metoprolol group and 15.3% in the placebo group (RR = 0.90). In conclusion, in patients with symptomatic heart failure metoprolol CR/XL once daily improved survival by 34%, sudden death by 41%, and deaths from worsening of heart failure by 49%. In addition to improvement of survival there was also a reduced need of hospitalizations for worsening heart failure and an improved NYHA functional class and of quality of life assessed in a substudy. Metoprolol was well tolerated with no difference in early discontinuation rate from placebo treatment.

Cardioprotection with beta-adrenoceptor blockers. Does lipophilicity matter?

Beta-blockers have several beneficial cardiovascular effects in patients with hypertension, angina pectoris, myocardial infarction, and congestive heart failure. In patients with myocardial infarction and congestive heart failure some beta-blockers have been found to reduce mortality and morbidity. The beta-blockers with a proven effect on prognosis include timolol, metoprolol, propranolol, bisoprolol, and carvedilol. One important question is whether all cardiovascular effects obtained by beta-blockers can be considered to be class effects. The beta-blockers with favorable effects on prognosis include two with more selective beta1-receptor blockade (metoprolol and bisoprolol) and three non-selective (timolol, propranolol and carvedilol). One non-selective beta-blocker, which also has a more pronounced class III effect, sotalol, has been studied in a large postinfarction study without a significant effect on mortality. However, sotalol reduced the incidence of reinfarction similarly to the other beta-blockers with proven effect on mortality after myocardial infarction. Sotalol had no influence at all on sudden cardiac death, while all the other beta-blockers referred to above have a very marked effect on sudden cardiac death, in fact more marked than on overall mortality. The beta-blockers with proven effect on mortality and on sudden death have one property in common and that is some degreee of lipophilicity. Sotalol and atenolol are hydrophilic. From animal experimental data it has been suggested that beta-bockers with some degree of lipophilicity penetrate into the brain and have an indirect effect on vagal activity, which is of importance for prevention of ventricular fibrillation and sudden cardiac death. It can be summarized that some beta-blockers have been found to reduce mortality and sudden cardiac death in patients after myocardial infarction and in congestive heart failure, while others have not. It seems that the major properties of the beta-blockers with proven effects on mortality and sudden cardiac death are beta1-receptor blockade and some degree of lipophilicity. Until we know more about the mechanisms behind prevention of death and especially sudden cardiac death by beta-blockers, only drugs with proven effects on prognosis should be used.

Searches for new interstellar molecules, including a tentative detection of aziridine and a possible detection of propenal

Rotational spectroscopy at millimeter wavelengths is a powerful means of investigating the chemistry of dense interstellar clouds. These regions can exhibit an interesting complement of gas phase molecules, including relatively complex organics. Here we report the tentative first astronomical detection of aziridine (ethylenimine), the possible detection of propenal (acrolein), and upper limits on the abundances of cyclopropenone, furan, hydroxyethanal (glycolaldehyde), thiohydroxylamine (NH2SH), and ethenol (vinyl alcohol) in various interstellar clouds.

Are patients truthful about their smoking habits? A validation of self-report about smoking cessation with biochemical markers of smoking activity amongst patients with ischaemic heart disease

AIMS

To validate self-report about smoking cessation with biochemical markers of smoking activity amongst patients with ischaemic heart disease.

PATIENTS AND METHODS

Outpatients at the Division of Cardiology, 75 years of age or younger, who had been Hospitalized at Sahlgrenska University Hospital in Göteborg due to an ischaemic event and who consecutively participated in a nurse-monitored routine care programme for secondary prevention, from 6 February 1997 to 5 February 1998. Data concerning smoking habits were collected through interviews. Two chemical markers, cotinine in plasma and carbon monoxide (CO) in expired air, validated self-reports concerning smoking cessation.

RESULTS

260 former smokers were validated. In the vast majority of the study population, the anamnestic information concurred with the chemical marker. However, 17 patients had chemical markers that contradicted their self-report with raised CO (n = 6) and/or raised cotinine levels (n = 13) without alternative nicotine delivery.

CONCLUSION

Most patients with coronary artery disease relating information concerning cessation of smoking are truthful. A few patients, however, seem to conceal their smoking. Testing by chemical markers may be questionable for ordinary care but should, however, be included in studies concerning the association between smoking and health.

Growth hormone improves bioenergetics and decreases catecholamines in postinfarct rat hearts

The aims of this study were to examine, in vivo, the effects of GH treatment on myocardial energy metabolism, function, morphology, and neurohormonal status in rats during the early postinfarct remodeling phase. Myocardial infarction (MI) was induced in male Sprague Dawley rats. Three different groups were studied: MI rats treated with saline (n = 7), MI rats treated with GH (MI + GH; n = 11; 3 mg/kg x day), and sham-operated rats (sham; n = 8). All rats were investigated with 31P magnetic resonance spectroscopy and echocardiography at 3 days after MI and 3 weeks later. After 3 weeks treatment with GH, the phosphocreatine/ATP ratio increased significantly, compared with the control group (MI = 1.69 +/- 0.09 vs. MI + GH = 2.42 +/- 0.05, P < 0.001; sham = 2.34 +/- 0.08). Treatment with GH significantly attenuated an increase in left ventricular end systolic volume and end diastolic volume. A decrease in ejection fraction was prevented in GH-treated rats (P < 0.05 vs. MI). Myocardial and plasma noradrenaline levels were significantly lower in MI rats treated with GH. These effects were accompanied by normalization of plasma brain natriuretic peptide levels (sham = 124.1 +/- 8.4; MI = 203.9 +/- 34.7; MI + GH = 118.3 +/- 8.4 ng/ml; P < 0.05 vs. MI). In conclusion, GH improves myocardial energy reserve, preserves left ventricular function, and attenuates pathologic postinfarct remodeling in the absence of induction of left ventricular hypertrophy in postinfarct rats. The marked decrease in myocardial content of noradrenaline, after GH treatment, may protect myocardium from adverse effects of catecholamines during postinfarct remodeling.

Induction of cardiomyopathy in severe combined immunodeficiency mice by transfer of lymphocytes from patients with idiopathic dilated cardiomyopathy

Growing evidence suggests that autoimmune mechanisms play an important role in the pathogenesis of idiopathic dilated cardiomyopathy (DCM). The aim of the study was to evaluate the effects of transfer of lymphocytes from patients with DCM into severe combined immunodeficiency (SCID) mice on the heart structure and function. Thirty CB-17 SCID (6-8 weeks old) mice were used and divided into 3 groups (n = 10). Mice were injected intraperitoneally with up to 25 x 10(6) peripheral blood lymphocytes (PBL) from either patients with DCM which contain human autoantibodies against cardiac beta1-adrenergic receptors and M2-muscarinic receptors (DCM group) or PBL from healthy controls (control-H group). Ten mice did not receive any injections and were used as baseline controls (control-N group). Echocardiography and morphological studies were performed seventy five days after the transfer. Results showed that in DCM group, left ventricle dimensions (LVD) in diastole were increased (4.2 +/- 0.1mm) as compared to both control-H group (3.8 +/- 0.1mm) and control-N group (3.6 +/- 0.1 mm) (p < 0.01). Further, there was a trend for increased LVD in systole. Fractional shortening was not different between groups. Histological evaluation revealed accumulation of human lymphocytes in the capillaries and scarce infiltration of the lymphocytes in the hearts from DCM group. Diffuse fibrosis was significant increased in DCM mice as compared to mice receiving PBL from normal subjects (2.2 +/- 0.3% vs. 0.8 +/- 0.1%, p < 0.01). In conclusion, transfer of the PBL from the patients with DCM was able to induce early stage of heart dilatation in SCID mice. These data provide for the first time the direct evidence supporting that the autoimmune mechanism is important in the pathogenesis of human DCM.

A novel polymorphism in the gene coding for the beta(1)-adrenergic receptor associated with survival in patients with heart failure

AIMS

The adrenergic nervous system is of major importance in congestive heart failure. No genetic polymorphism has previously been identified in the beta(1)-adrenergic receptor gene. The aim of this study was to find possible mutations in this gene and to relate such findings to morbidity and prognosis in heart failure.

METHODS AND RESULTS

Genomic DNA was extracted from blood leukocytes from patients with congestive heart failure (n=184) and from age-matched controls (n=77). The part of the beta(1)-adrenergic receptor gene corresponding to nucleotide 1-255 was amplified by polymerase chain reaction and analysed by automated sequencing. The patients were investigated by echocardiography and followed regarding symptoms and survival for 5 years. A missense mutation was identified at nucleotide position 145 in the beta(1)-adrenergic receptor gene, which predicted an amino acid substitution at position 49 (Ser49Gly). The allele frequency of the Gly49 variant was 0.13 in controls and 0.18 in patients (P=0.19). At the time of the 5-years follow-up, 62% of the patients with the wild type gene and 39% of the patients with the Ser49Gly variant had died or had experienced hospitalization (P=0.005). Patients without the mutation had significantly poorer survival compared to those with the mutation, risk ratio 2.34 (95% CI 1.30-4.20), P=0.003. In a mulivariate analysis, the risk ratio was 2.03 (95% CI 0.99-4.16) P=0.05.

CONCLUSION

A novel missense mution in the beta(1)-adrenergic receptor gene was associated with a decreased mortality risk in patients with congestive heart failure. These data suggest that the beta(1)-receptor Ser49Gly variant might be associated with altered receptor function, resulting in myocardial protection in patients with heart failure.

Effects on heart rate variability of isosorbide-5-mononitrate and metoprolol in patients with recent onset of angina pectoris

BACKGROUND

Beta-blockers reduce sympathetic tone, increase vagal tone and improve prognosis in ischaemic heart disease. Nitroglycerin, being a vasodilator, may theoretically have an opposite effect and worsen the prognosis. The purpose of the present study was to analyse heart rate variability (HRV), which reflects autonomic tone, in angina patients on isosorbide-5-mononitrate (IS-5-MN) and/or metoprolol.

METHODS AND RESULTS

Thirty-two patients (32-81 years old), with recently developed angina (median duration: 3 months), showing no other disease and on no drugs, were Holter-monitored 24-48 h at baseline and after 4-5 days on IS-5-MN (mean daily dose: 33 mg), on metoprolol (mean daily dose: 184 mg) and on the combined treatment. Recordings were analysed on the Marquette Series 8000 Holter scanner. Both IS-5-MN and metoprolol significantly reduced myocardial ischaemia (ST integral) and ventricular tachycardias. Metoprolol induced significant changes in the following parameters (baseline versus metoprolol): high-frequency peak 9 +/- 4 versus 11 +/- 4 ms (p < 0.001), low-to-high frequency ratio 2.5 +/- 0.6 versus 1.9 +/- 0.6 (p < 0.0001), root mean square of RR interval difference 23 +/- 7 versus 31 +/- 9 ms (p < 0.0001), RR intervals differing more than 50 ms from the preceding one 4.8 +/- 3.9 versus 10.0 +/- 7.0% (p < 0.0001), mean of all 5-min standard deviations 50 +/- 12 versus 56 +/- 11 ms (p < 0.001) and mean RR interval 819 +/- 90 versus 1,019 +/- 120 ms (p < 0.00001). The combined treatment caused approximately the same HRV changes as metoprolol alone. IS-5-MN had no significant effect on any HRV parameter, neither alone nor in combination with metoprolol.

CONCLUSION

A clinically effective dose of metoprolol had potentially positive effects on HRV with increase in vagal and decrease in sympathetic tone while IS-5-MN had no effect on HRV, neither positive nor negative, neither alone nor in combination with metoprolol.

Stimulatory activity of anti-peptide antibodies against the second extracellular loop of human M2 muscarinic receptors

OBJECTIVE

To study the activity of anti-peptide antibodies against the second extracellular loop of human M2 muscarinic receptors on cAMP production and inward calcium currents (Ica) in guinea pig ventricular myocytes. A comparison was also made with those of a muscarinic receptor agonist.

METHODS

cAMP content was determined by radioimmunoassay and the Ica in guinea pig single ventricular cells were recorded by the whole-cell patch clamp technique.

RESULTS

Both the muscarinic receptor agonist, carbachol (Carb 10 mumol/L), and anti-peptide antibodies (Abs 100 nmol/L) could decrease basal cAMP levels (by 46.9% +/- 4.2% and 60.2% +/- 4.6%, respectively) and basal Ica. Both Carb (10 mumol/L) and Abs (100 nmol/L) could also inhibit the isoprenaline-induced (Iso 0.8 mumol/L) increases in cAMP production (from 108.2 +/- 7.0 to 88.4 +/- 7.2 pmol/mg.protein/min for Carb and 88.6 +/- 5.1 pmol/mg.protein/min for Abs, respectively) and the increases in Ica. The muscarinic receptor antagonist atropine (Atr) was able to prevent these effects of Carb and Abs.

CONCLUSIONS

Anti-peptide antibodies against an epitope located in the second extracellular loop of human M2 muscarinic receptors, similar to muscarinic receptor agonist, could decrease the basal Ica and beta-receptor agonist stimulated increase of Ica by decreasing the basal and beta-receptor agonist stimulated increase of cAMP production, and therefore could have an effect on their target receptor. These results further suggest that autoimmunity may participate in the pathogenesis of human cardiomyopathy and the second extracellular loop of human M2 muscarinic receptor could be the main immunodominant region.

Autoantibodies against the angiotensin receptor (AT1) in patients with hypertension

Sera from patients with malignant essential hypertension (n = 14), malignant secondary hypertension mainly attributable to renovascular diseases (n = 12) and renovascular diseases without malignant hypertension (n = 11) and from normotensive healthy blood donors (n = 35) were studied for the presence of autoantibodies against G-protein-coupled cardiovascular receptors. Autoantibodies against the angiotensin II receptor (AT1) were detected in 14, 33, 18 and 14% of patients with malignant essential hypertension, malignant secondary hypertension, renovascular diseases and control patients, respectively. Sensitivity of the enzyme immunoassay was assessed as 5 microg/ml IgG. Patients did not show antibodies against bradykinin (B2) or angiotensin II subtype 2 (AT2) receptors. Autoantibodies affinity-purified from positive patients localized AT receptors in Chinese hamster ovary transfected cells, and displayed a positive chronotropic effect on cultured neonatal rat cardiomyocytes. These results demonstrate the existence of autoantibodies against a functional extracellular domain of human AT1 receptors in patients with malignant hypertension, and suggest that these autoantibodies might be involved in the pathogenesis of malignant hypertension.

Myocardial hypertrophy in transgenic mice overexpressing the bovine growth hormone (bGH) gene

OBJECTIVES

The main purpose of the present study was to characterize cardiac muscle hypertrophy using both qualitative and quantitative microscopy in mice overexpressing the bovine growth hormone.

RESULTS

Measurements of 30 fibres from each group revealed that fibre diameter in transgenic hearts was significantly larger than in control hearts. There was a significant decrease in interfibrillar space in transgenic hearts as compared with control hearts. The enlarged transgenic hearts displayed unchanged organelles such as normal myofibrils and mitochondria in a normal pattern, suggesting balanced growth. Myelin structures were occasionally observed between normal myofibrils. Moreover, myocardial beta-adrenergic receptors and muscarinic receptors in the hearts of transgenic mice overproducing GH were studied to see whether they are involved in the hypertrophic process. It was shown that the density of muscarinic receptors had decreased and the super-high affinity of muscarinic receptors was lost, without any significant changes in either the density or the affinity of beta-adrenergic receptors, as compared with controls.

CONCLUSIONS

These results demonstrate that a GH excess was able to induce significant myocardial hypertrophy and that there was a downregulation of muscarinic receptors.

In vivo metabolic imaging of cardiac bioenergetics in transgenic mice

Recent advances in transgenic technology have made the mouse a particularly interesting small animal in cardiovascular research. Increasingly sophisticated experimental methods and tools are needed for detailed characterization of cardiovascular physiology and biochemistry in the mice. The objective of this study was to develop a method for noninvasive evaluation of cardiac energy metabolism in the mouse. Cardiac gated (31)P magnetic resonance spectroscopy using Image Selected in Vivo Spectroscopy (ISIS) method was applied in old mice overexpressing bovine growth hormone (bGH) (n = 5) and control mice (n = 5). The localized volumes of interest were 128 and 112 microL, respectively. Phosphocreatine-to-ATP ratio was 1.5 +/- 0.13 in the bGH mice and 2.1 +/- 0.04 in the control group (P < 0.01). The study demonstrates the feasibility of application of volume-selective (31)P MRS for evaluation of cardiac energy metabolism in the mouse under maintained physiological conditions.

A monoclonal antibody directed against an autoimmune epitope on the human beta1-adrenergic receptor recognized in idiopathic dilated cardiomyopathy

A monoclonal antibody (MAb M16) was obtained by immunizing Balb/C mice with free peptide H26R, corresponding to the second extracellular loop of the human beta1-adrenergic receptor (beta1AR), against which functional autoantibodies have been detected in patients with idiopathic dilated cardiomyopathy. The MAb was found to be of IgG2b type and directed against a conformational epitope, encompassing the sequence recognized by the human autoantibodies. BIAcore measurements yielded an equilibrium constant of 6.5 X 10(7) M1 with an association rate constant (kon) of 6.5 X 10(4) M(-1) sec(-1) and a dissociation rate constant (koff) of 1.0 X 10(-3) sec(-1). It immunoprecipitated only poorly the solubilized beta1AR of Sf9 cell membranes. Functionally, the MAb was capable of not only reducing the number of the maximal binding sites to the beta1-adrenergic receptor of transfected Sf9 cell membranes, but also of displaying a positive chronotropic effect on cultured neonatal rat cardiomyocytes. These properties, which the MAb shares with the human autoantibodies, makes it an interesting tool for passive transfer studies in mice.

Effects of controlled-release metoprolol on total mortality, hospitalizations, and well-being in patients with heart failure: the Metoprolol CR/XL Randomized Intervention Trial in congestive heart failure (MERIT-HF). MERIT-HF Study Group

CONTEXT

Results from recent studies on the effects of beta1-blockade in patients with heart failure demonstrated a 34% reduction in total mortality. However, the effect of beta1-blockade on the frequency of hospitalizations, symptoms, and quality of life in patients with heart failure has not been fully explored.

OBJECTIVE

To examine the effects of the beta1-blocker controlled-release/extended-release metoprolol succinate (metoprolol CR/XL) on mortality, hospitalization, symptoms, and quality of life in patients with heart failure.

DESIGN

Randomized, double-blind controlled trial, preceded by a 2-week single-blind placebo run-in period, conducted from February 14, 1997, to October 31, 1998, with a mean follow-up of 1 year.

SETTING

Three hundred thirteen sites in 14 countries.

PARTICIPANTS

Patients (n = 3991) with chronic heart failure, New York Heart Association (NYHA) functional class II to IV, and ejection fraction of 0.40 or less who were stabilized with optimum standard therapy.

INTERVENTIONS

Patients were randomized to metoprolol CR/XL, 25 mg once per day (NYHA class II), or 12.5 mg once per day (NYHA class III or IV), titrated for 6 to 8 weeks up to a target dosage of 200 mg once per day (n = 1990); or matching placebo (n = 2001).

MAIN OUTCOME MEASURES

Total mortality or any hospitalization (time to first event), number of hospitalizations for worsening heart failure, and change in NYHA class, by intervention group; quality of life was assessed in a substudy of 741 patients.

RESULTS

The incidence of all predefined end points was lower in the metoprolol CR/XL group than in the placebo group, including total mortality or all-cause hospitalizations (the prespecified second primary end point; 641 vs 767 events; risk reduction, 19%; 95% confidence interval [CI], 10%-27%; P<.001); total mortality or hospitalizations due to worsening heart failure (311 vs 439 events; risk reduction, 31%; 95% CI, 20%-40%; P<.001), number of hospitalizations due to worsening heart failure (317 vs 451; P<.001); and number of days in hospital due to worsening heart failure (3401 vs 5303 days; P<.001). NYHA functional class, assessed by physicians, and McMaster Overall Treatment Evaluation score, assessed by patients, both improved in the metoprolol CR/XL group compared with the placebo group (P = .003 and P = .009, respectively).

CONCLUSIONS

In this study of patients with symptomatic heartfailure, metoprolol CR/XL improved survival, reduced the need for hospitalizations due to worsening heart failure, improved NYHA functional class, and had beneficial effects on patient well-being.

Patients with uncomplicated coronary artery disease have reduced heart rate variability mainly affecting vagal tone

AIM

To investigate whether uncomplicated chronic coronary artery disease causes changes in heart rate variability and if so, whether the heart rate variability pattern is different from that described in patients with acute myocardial infarction.

METHODS

Heart rate variability was studied in 65 patients with angina who had no previous myocardial infarcts, no other diseases, and were on no drug that could influence the sinus node. Results were compared with 33 age matched healthy subjects. The diagnosis of coronary artery disease in angina patients was established by coronary angiography in 58, by thallium scintigraphy in six, and by exercise test only in one. Patients and controls were Holter monitored 24 hours outside hospital, and heart rate variability was calculated in the frequency domain as global power (GP: 0.01-1.00 Hz), low frequency peak (LF: 0. 04-0.15 Hz), high frequency peak (HF: 0.15-0.40 Hz), LF/HF in ms(2), and in the time domain as SDNN (SD of normal RR intervals), SDANN (SD of all five minute mean normal RR intervals), SD (mean of all five minute SDs of mean RR intervals), rMSSD (root mean square of differences of successive normal RR intervals) (all in ms), and pNN50 (proportion of adjacent normal RR intervals differing more than 50 ms from the preceding RR interval) as per cent.

RESULTS

The mean age in patients and controls was 60.4 (range 32-81) and 59.1 (32-77) years, respectively (NS), the male/female ratio, 57/65 and 24/33 (NS), and the mean time of Holter monitoring, 23.0 (18-24) and 22.8 (18-24) hours (NS). Mortality in angina patients was 0% (0/65) at one year, 0% (0/56) at two years, and 3% (1/33) at three years. Compared with healthy subjects angina patients showed a reduction in GP (p = 0.007), HF (p = 0.02), LF (p = 0.02), SD (p = 0.02), rMSSD (p = 0.01), and pNN50 (p = 0.01). No significant difference was found in RR, LF/HF, SDNN, or SDANN.

CONCLUSIONS

Uncomplicated coronary artery disease without previous acute myocardial infarction was associated with reduced high and low frequency heart rate variability, including vagal tone. SDANN and SDNN, expressing ultra low and very low frequencies which are known to reflect prognosis after acute myocardial infarction, were less affected. This is in agreement with the good prognosis in uncomplicated angina in this study.

Supervised physical activity in Sweden: in theory and practice

The aim of this study was to assess to which extent community-run projects including physical activity could be identified, described and analysed in terms of objectives, organisation, evaluation and financing, as a resource in prevention and treatment of common lifestyle-related medical problems. The Swedish database Spriline was used as a main source of information. Identification of ongoing Swedish activities was followed by a mail questionnaire. In total, 151 projects were eventually identified. A semistructured questionnaire containing about 30 questions was mailed to the individual listed as responsible for the project, with a reminder 2 months later. Only 52 projects were viable; a follow-up of nonresponders showed that no relevant activity program had ever existed or that the person responsible had left. Walking, aerobics and water activities were the dominating types of activity. Most projects addressed both sexes, but eight weight reduction programs were designed for women only. Evaluation ranged from 'measuring attendance' to 'scientific evaluation'. Physical activity programs may not be as systematically organised as the Swedish database suggests and cannot generally be relied upon as support in patient care, unless critically evaluated in advance.

The growth hormone secretagogue hexarelin improves cardiac function in rats after experimental myocardial infarction

Several studies have shown that GH can enhance cardiac performance in rats after experimental myocardial infarction and in humans with congestive heart failure. In the present study, the hemodynamic effects of hexarelin (Hex), an analog of GH-releasing peptide-6 and a potent GH secretagogue, were compared with the effects of GH. Four weeks after ligation of the left coronary artery male rats were treated sc twice daily with hexarelin [10 microg/kg x day (Hex10) or 100 microg/kg x day (Hex100)], recombinant human GH (2.5 mg/kg x day), or 0.9% NaCl for 2 weeks. Transthoracic echocardiography was performed before and after the treatment period. GH, but not Hex, increased body weight gain. GH and Hex100 decreased total peripheral resistance (P < 0.05) and increased stroke volume (P < 0.05 and P < 0.01, respectively) and stroke volume index (P = 0.06 and P < 0.01, respectively) vs. NaCl. Cardiac output was increased by GH and Hex100 (P < 0.05), and cardiac index was increased by Hex100 with a borderline significance for GH (P = 0.06). In conclusion, Hex improves cardiac function and decreases peripheral resistance to a similar extent as exogenous GH in rats postmyocardial infarction. The mechanisms of these effects are unclear; they could be mediated by GH or a direct effect of Hex on the cardiovascular system.

The mortality effect of metoprolol CR/XL in patients with heart failure: results of the MERIT-HF Trial

The study was undertaken to investigate the effect of metoprolol CR/XL on all-cause mortality in patients with heart failure in New York Heart Association (NYHA) class II-IV. In all, 3,991 patients in NYHA class II-IV who were stable on standard medical treatment, including angiotensin-converting enzyme inhibitors, diuretics, and digitalis, were randomized to metoprolol CR/XL or placebo and uptitrated from 12.5 or 25 mg to 200 mg over an 8-week period and were planned to be followed for a period of 2 years. The study was stopped earlier than planned due to the significant benefit achieved with metoprolol CR/XL on all-cause mortality. Treatment with metoprolol CR/XL was associated with a 34% decrease in all-cause mortality, 38% decrease in cardiovascular mortality, 41% decrease in sudden death, and 49% decrease in death due to progressive heart failure. The average dose of metoprolol CR/XL at the end of the study was 159 mg, and 64% of the patients were receiving 200 mg of metoprolol CR/XL. There was no significant difference in the placebo and active treatment group with regard to permanent discontinuation. Treatment of patients in NYHA class II-IV with metoprolol CR/XL is associated with a significant decrease in total mortality.

Prevention of sudden cardiac death with beta blockers

Beta blockers have been shown to reduce the risk of sudden cardiac death in more than 50 randomized trials involving more than 55,000 patients. Relative reductions (vs. placebo) in cardiac death in some of these trials ranged from 30 to 50%. These reductions are substantially greater than trials of other drug classes including angiotensin-converting enzyme inhibitors. However, not all beta blockers confer equal benefit to patients at risk of sudden cardiac death. Results from various trials suggest that lipophilic beta blockers--such as timolol, metoprolol, propranolol, bisoprolol, and carvedilol--may be more beneficial than hydrophilic beta blockers. Results of animal studies have indicated that sudden cardiac death is mediated, at least in part, by the central nervous system, which may account for why lipophilic agents have more pronounced clinical effects. Based on the results of numerous clinical and mechanistic studies, it is suggested that beta blockers should be given to all patients at risk for sudden cardiac death, including those patients with previous myocardial infarction, hypertension, or congestive heart failure.

Bioenergetic, functional and morphological consequences of postinfarct cardiac remodeling in the rat

Despite recent advances in the treatment, severe chronic heart failure (CHF) remains a syndrome associated with high mortality. Therefore, the search for new agents to improve both patient symptoms and survival, as well as the pursuit for detailed knowledge about pathophysiology of the failing heart, will continue to depend on relevant animal models. Large acute myocardial infarction (MI) initiates complex changes in the geometrical, structural, and biochemical architecture of both infarcted and non-infarcted regions of ventricular myocardium, which can profoundly affect left ventricular function and prognosis. In this paper we present a new model for non-invasive cardiac (31)P MRS in the rat. Volume-selective (31)P magnetic resonance spectroscopy and echocardiography were used for evaluation of myocardial energy metabolism, cardiac morphology and function in rats 3 days and 3 weeks after induction of large MI. The phosphocreatine:adenosine triphosphate (PCr:ATP) ratio was decreased in rats with MI comparing with controls both at 3 days (1.6+/-0.06 vs 2.7+/-0.04; mean+/-s.e.m. P<0.0001) and 3 weeks (1.6+/-0.07 v 2.7+/-0.02 P<0.0001) postinfarct. The results from the study demonstrate that postinfarct cardiac remodeling is a rapid process of changes not only in cardiac geometry, structure and function but also in myocardial energy metabolism after large transmural MI in the rat.

Probing the immunological properties of the extracellular domains of the human beta(1)-adrenoceptor

The human beta(1)-adrenoceptor is an immune target for autoantibodies with functional activity in cardiovascular diseases. Different epitopes on the extracellular domains of the receptor are involved. To study the immunological and pharmacological properties of these epitopes, rabbits were immunized with peptides corresponding to a large domain in the N-terminal part of the receptor and to its first and second extracellular loops. In contrast to the two other peptides, the first extracellular loop did not have immunogenic properties but acted as a hapten. Antibodies affinity-purified with the three synthetic peptides were able to significantly immunoprecipitate the solubilized receptor, confirming that they recognized the target receptor. While antibodies against the N-terminal domain did not inhibit the binding of a radiolabelled antagonist to the receptor, those against the first and second extracellular loop showed non-competitive inhibition. Similarly, only the two latter antibodies exerted a specific agonist-like effect on the receptor, as assessed on neonatal rat cardiomyocytes in culture. Our results are in accordance with those found for human anti-receptor autoantibodies with functional effects. We conclude that not all extracellular epitopes give rise to functional autoantibodies with potential physiopathological relevance in cardiac diseases with an autoimmune component.

Autoantibodies against M2 muscarinic receptors in patients with cardiomyopathy display non-desensitized agonist-like effects

Circulating autoantibodies against the human M2 muscarinic receptors have been previously shown in 38% of patients with idiopathic dilated cardiomyopathy. The functional properties of these autoantibodies are reported herein. They were able to decrease the cell beating frequency of myocytes in cultured neonatal rat heart cells in a dose-dependent manner without desensitization over a period of more than 5 hours whereas the non-specific muscarinic receptor agonist carbachol also inhibited the heart cell beating frequency but was desensitized within 1 hour. In the same cell culture, anti-M2 muscarinic receptor autoantibodies were not able to induce internalization of muscarinic receptor whereas carbachol did. These results demonstrate for the first time that anti-M2 muscarinic receptor autoantibodies from patients with idiopathic dilated cardiomyopathy have stimulatory muscarinic activity in vitro, which differ from normal muscarinic agonists by non-desensitization.

Potential risk of beta-blockade withdrawal in congestive heart failure due to abrupt autonomic changes

Beta-Blockers reduce mortality in patients with congestive heart failure and a proposed mechanism has been changes of autonomic tone. Heart rate variability is a non-invasive tool to estimate cardiac autonomic tone. The aim was to study changes of heart rate variability in patients with congestive heart failure on placebo, on the beta1-selective antagonist metoprolol or 24 h after metoprolol withdrawal. Forty-five patients with congestive heart failure were studied with Holter recordings. Heart rate variability measurements were performed before, after 6-12 months of treatment with 150 mg metoprolol/placebo, or 24 h after discontinued metoprolol. After treatment, patients on beta-blockade had a significantly longer mean RR interval and changes of heart rate variability, suggesting elevated vagal tone. Patients monitored in the rebound phase of beta-blocker withdrawal had a significant vagal reduction to the level of the placebo group. There was also a nonsignificant trend towards increased sympathetic tone (LF/HF over 24 h), compared with the beta-blockade group. Heart rate variability indicates an elevated vagal tone during treatment with metoprolol but beta-blockade withdrawal shifts the autonomic balance towards lower vagal and higher sympathetic tone within 24 h. These results could imply a potential risk when abruptly discontinuing beta-blockade medication in these patients.

Immunohistochemical localization of angiotensin II receptors (AT1) in the heart with anti-peptide antibodies showing a positive chronotropic effect

Antibodies were produced against a synthetic peptide corresponding to amino acids (165-191) of the second extracellular loop of the human angiotensin II receptor subtype 1 (AT1) in rabbits. The purified antibodies had an apparent affinity of about 1 nM and were monospecific for the AT1-receptor peptide. Chemical modification of the carboxyl groups (glu at positions 173 and 185) and the sulfhydryl group (cys at position 180) of the AT1-receptor peptide did not alter the relative affinity of the coated AT1-receptor peptide to antibodies. The antibodies specifically stained CHO cells expressing the rat AT1a receptor. Immunoblots on rat kidney revealed that the antibody recognized a protein band of 59 +/- 3 kDa in a dose-dependent manner and this band was no longer detected after preincubating the antibodies with AT1-receptor peptide. Using electron microscopic and immunofluorescence immunocytochemistry techniques, angiotensin II receptors were detected in (1) the sarcolemma, T-tubules and nuclei of rat cardiomyocytes, (2) the transluminal side of endothelial cells and (3) fibroblast cells. These localizations are specific, as the immunostaining did not appear when preimmune rabbit serum was used and was blocked after preincubating antibodies with antigenic peptide. Functionally, these antibodies did not affect the ligand binding properties of the receptors but displayed agonist-like activity as shown by dose-dependent increases in beating frequency in cultured neonatal cardiomyocytes. These results suggest that the antibodies against the second extracellular loop of human AT1 receptors were able to specifically recognize AT1 receptors. In addition, they extend the observation that the second extracellular loop of the G-protein coupled membrane receptors is a specific target for antibodies with agonist-like activity.

Density structure of the Sgr B2 molecular cloud probed by low-J lines of CS

We have observed the CS (2-1) and (3-2), and 13CS (2-1) transitions toward the Galactic Center molecular cloud Sgr B2 which consists of several clumps with different chemical properties. We have newly identified a cloud at 30 km s-1 from a CS (2-1) optical depth map. This cloud lies 1.5' South from the Sgr B2 (M) position and has a diameter of approximately 2.5 pc and a total column density of 7 x 10(23) cm-2 assuming optically thin emission of the 13CS (2-1) line. Towards the 2'N Cloud no evidence for a density enhancement is found, which suggests that the strong emission from HNCO and HCO+2 is due to chemical effects. The main isotopic CS lines show broad wing components similar to previous studies, but we find rotational temperatures Trot(CS) < 10 K at this region.

Significance of reduction in heart rate in cardiovascular disease

Epidemiologic studies suggest that lower heart rate is associated with decreased cardiovascular and all-cause mortality. Heart rate has also been reported to be an independent predictor of outcome after myocardial infarction (MI). Because it is a major determinant of oxygen consumption and metabolic demand, a decrease in heart rate would be expected to decrease cardiac workload. Among patients with restricted coronary blood flow, increased heart rate is associated with more severe myocardial ischemia, angina, and an increase in size of MI. Pharmacologic interventions that reduce heart rate, such as beta blockers, generally reduce mortality and improve outcome. A number of clinical trials using beta blockers after MI has shown a relationship between reduction in heart rate and reduction in mortality. Most beta blockers demonstrate a nearly linear relationship between reductions in mortality and in heart rate. The evidence from trials with calcium antagonists is more equivocal, possibly because until very recently none were available that decreased heart rate without decreasing myocardial contractility. Drugs that do not reduce the heart rate after an MI and in congestive heart failure have not been found to improve survival. In light of the findings thus far reported, reduction in heart rate should be a therapeutic goal in the treatment of cardiovascular disease.

A placebo-controlled study of growth hormone in patients with congestive heart failure

AIM

Experimental data in heart failure models and an open trial of seven patients with idiopathic dilated cardiomyopathy have suggested beneficial effects of growth hormone on cardiac function. The aim of the present study was to evaluate growth hormone effects on cardiac function in a placebo-controlled study.

METHODS

Twenty two patients with congestive heart failure of different aetiologies in NYHA II and III and an echocardiographic ejection fraction <0.45 were studied in a 3 month double-blind placebo-controlled study with growth hormone added to optimal heart failure therapy. Patients received either placebo (n=11) or recombinant human growth hormone (n=11) in an initial dose of 0.1 IU x kg(-1) week(-1) for 1 week, and thereafter 0.25 IU x kg(-1) week(-1) for the rest of the treatment period. Cardiac function was assessed by equilibrium radionuclide angiography and Doppler echocardiography. Functional capacity was evaluated by computerized bicycle exercise electrocardiography.

RESULTS

Recombinant human growth hormone had no significant effect on systolic or diastolic cardiac function, exercise capacity or neuroendocrine activation. In addition, there was no overall improvement in functional class or dyspnoea grade. Insulin-like growth factor-I significantly increased demonstrating that the growth hormone had an endocrine effect.

CONCLUSION

This is the first double-blind and placebo-controlled study of the administration, over 3 months, of recombinant human growth hormone in patients with congestive heart failure of different aetiologies. The treatment was safe and without serious side effects. However, no beneficial effects on cardiac function or structure could be detected.