Induction of DNA breaks in cardiac myoblast cells by norepinephrine

We measured DNA single strand breaks (SSB) in cardiac myoblast cells in response to norepinephrine (NE) stimulation. Rat cardiac myoblast cells (H9c2) were stimulated with concentrations of 100 microMs to 1 mM NE for 2, 3, 4, and 12 hours after prior incubation with control solution, bunazosin, propranolol, verapamil, or captopril for 30 min. The DNA damage was measured by fluorometric alkaline elution. The strand scission factor, an index of the severity of SSB, increased slightly after stimulation with 200 microMs NE for 12 hours and with 1 mM NE for 4 hours. This increase was prevented by catalase or superoxide dismutase, which prevent production or accumulation of active oxygen radicals, during the stimulation, but not by pretreatment with a alpha-receptor antagonist, a beta-adrenergic receptor antagonist, a Ca2+ antagonist, or an angiotensin converting enzyme inhibitor. Thus, DNA SSB were induced by NE in cardiac myoblast cells. Certain active oxygen species may contribute to the DNA damage induced by NE.

Twenty-five-year prediction of stroke deaths in the seven countries study: the role of blood pressure and its changes

BACKGROUND AND PURPOSE

This report explores the prediction of long-term stroke mortality in cohorts of the Seven Countries Study.

METHODS

Sixteen cohorts of men aged 40 to 59 years at entry were examined at years 0, 5, and 10, with mortality follow-up through 25 years.

RESULTS

Stroke death rates in 25 years were high in rural Serbia, Croatia, and Japan; intermediate in Italy, Greece, and urban Serbia; and low in Finland, the Netherlands, and the United States. Age and blood pressure were powerful predictors of 25-year stroke mortality in almost all cohorts and countries. Proportional hazards regression coefficients were .0232 increase in stroke death hazard per millimeter of mercury (t=14.60) for systolic blood pressure and .0409 (t=13.41) for diastolic blood pressure. Moderate blood pressure increases from low usual levels were associated with lower stroke mortality rates in years 10 to 25. Increases of blood pressure starting from high usual levels were associated with increased rates of stroke mortality. Systolic blood pressure was associated with stroke mortality at given levels of diastolic pressure, but diastolic blood pressure was not predictive of stroke mortality at given levels of systolic blood pressure.

CONCLUSIONS

Associations of systolic and diastolic blood pressure with stroke mortality were similar in cultures with different stroke mortality rates. Increases in blood pressure were associated with subsequent excess stroke mortality only in those who started from high usual levels; this study finds lower stroke risk in those men whose blood pressure increased moderately from low usual levels. Diastolic blood pressure is not independently associated with stroke risk in these populations.

Chronic L-arginine administration attenuates cardiac hypertrophy in spontaneously hypertensive rats

Nitric oxide inhibits proliferation and migration of vascular smooth muscle cells and contractility of cardiomyocytes in vitro. In spontaneously hypertensive rats (SHR), evidence suggests intrinsic abnormalities of the L-arginine-nitric oxide axis, such as low cGMP-dependent protein kinase in the heart and abnormal L-arginine metabolism. To investigate the in vivo effect of L-arginine on cardiac hypertrophy, 30 SHR and 30 Wistar-Kyoto rats (WKY) were randomly grouped to receive L-arginine (7.5 g/L in drinking water) or vehicle for 12 weeks. L-Arginine treatment did not affect body weight or arterial pressure in either strain. In vehicle-treated animals, the heart/body weight ratio was significantly higher in SHR than in WKY (P < .01). L-Arginine treatment decreased the heart/body weight ratio in SHR (P < .05) but did not affect it in WKY. Expression of skeletal alpha-actin mRNA, known to be expressed in the hypertrophied myocardium, was attenuated in L-arginine-treated SHR compared with vehicle-treated SHR. Cardiac cGMP content and nitrate/nitrite content were less in SHR than WKY. L-Arginine treatment increased these levels only in SHR, suggesting enhanced nitric oxide production. Thus, chronic L-arginine administration attenuated cardiac hypertrophy independently of blood pressure and increased myocardial content of cGMP and nitrate/nitrite. Our results suggest that abnormality of the cardiac L-arginine-nitric oxide axis may play an important role in the pathogenesis of cardiac hypertrophy in SHR.

Disappearance of giant negative T waves in patients with the Japanese form of apical hypertrophy

OBJECTIVES

The present study investigated the long-term changes in the electrocardiographic (ECG) hallmarks of the Japanese form of apical hypertrophy.

BACKGROUND

Giant negative T waves and tall R waves in the left precordial leads are the ECG hallmarks of the Japanese form of apical hypertrophy. However, the long-term course is largely unknown.

METHODS

Twenty-nine patients with apical hypertrophy (26 men, 3 women, mean age +/- SD 50.4 +/- 8.2 years) who showed left precordial giant negative T waves (< or = -10 mm) and tall R waves (> or = 26 mm) and spade configuration in the left ventriculogram were followed up for 10.9 +/- 3.7 years.

RESULTS

The intermediate follow-up ECGs (5 to 9 years) showed disappearance of giant negative T waves in 31% and of tall R waves in lead V5 in 6%. At the long-term follow-up study (> or = 10 years), loss of giant negative T waves increased to 71%, with average T wave negativity in lead V4 or V5 decreasing from -16.5 +/- 5.1 to -6.9 +/- 4.2 mm. These T wave changes were associated with decreases in R wave amplitude in lead V5 from 40.7 +/- 9.6 to 26.1 +/- 13.8 mm, with loss of tall R waves in lead V5 in 38% of patients and development of abnormal Q waves in two patients.

CONCLUSIONS

During the long-term follow-up of the Japanese form of apical hypertrophy, giant negative T waves disappeared in association with decreases in R wave amplitude in lead V5, indicating that these ECG hallmarks are clinical features that evolve progressively during the natural course of the disease.

DNA typing of HLA class II genes in Japanese patients with dilated cardiomyopathy

HLA class II genes (DRB, DQA, DQB, DPA, and DPB) were typed at the DNA level using polymerase chain reaction/sequence-specific oligonucleotide probe analysis in 78 unrelated patients with DCM and 336 unrelated healthy controls to elucidate the HLA alleles or HLA haplotypes associated with DCM. The frequencies of DRB1*1401 (15.4% v 4.5%, RR = 3.90, P < 0.0005, Pc < 0.03), DQB1*0503 (14.1% v 5.4%, RR = 2.93, P < 0.007) and DRB1*1401-DQB1*0503 haplotype (11.5% v 1.5%, RR = 8.24, P < 0.00001, Pc < 0.01) were increased in the DCM patients. The frequency of HLA-DRB1*1101 (9.0% v 3.0%, RR = 3.26, P < 0.02) also was increased in the patients. In addition, the frequencies of DQB1*0604 and DPB1*0401 were increased in the DRB1*1401 and DRB1*1101 negative patients. In contrast, the frequencies of DQB1*0303 (19.2% v 30.7%, RR = 0.55, P < 0.05) and DRB1*0901-DQB1*0303 haplotype (16.7% v 29.8%, RR = 0.49, P < 0.02) were decreased in the DCM group. Disease susceptibility to DCM in the Japanese population, thus, may be controlled in part by a gene (or genes) in close linkage disequilibrium with DRB1*1401-DQB1*0503, DRB1*1101-DQB1*0301, and DQB1*0604-DPB1*0401 haplotypes, while the resistance to DCM may be associated with the DRB1*0901-DQB1*0303 haplotype.

A myosin missense mutation, not a null allele, causes familial hypertrophic cardiomyopathy

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is characterized by myocardial hypertrophy of unknown etiology. Missense mutations of the cardiac beta-myosin-heavy-chain (beta-MHC) gene that may be responsible for cardiac hypertrophy have been detected in patients with HCM. On the other hand, gross structural abnormalities in the cardiac beta-MHC gene, ie, an alpha/beta hybrid gene and partial deletion of the gene, have also been reported. The direct correlation between gross abnormalities and development of HCM is not well understood.

METHODS AND RESULTS

We analyzed the structure of the cardiac beta-MHC gene from patients with HCM by using polymerase chain reaction-DNA conformation polymorphism analysis and found two sequence variations in exons 3 and 22 in one patient. These sequence variations at codon 54 (exon 3; nonsense mutation) and codon 870 (exon 22; Arg-to-His mutation) were identified by direct sequencing and dot-blot hybridization with allele-specific oligonucleotide probes. Relatives of this patient were examined for the mutations. It was revealed that the missense mutation was inherited from the affected father and the nonsense mutation from the unaffected grandmother through the unaffected mother. In addition, the missense mutation was also found in seven other patients from two other unrelated multiplex HCM families.

CONCLUSIONS

The Arg870His mutation was suggested to cause HCM. In contrast, the gene with the nonsense mutation would encode for a cardiac beta-MHC protein of only 53 amino acid residues, which may be too short to be incorporated into the thick filament assembly of cardiac myosin chains and showed no dominant phenotype of heart disease. This is the first report of a nonsense mutation in the human cardiac beta-MHC gene.

Follow-up of 2,733 Japanese patients with myocardial infarction

Two thousand, seven hundred and thirty-three patients with acute myocardial infarction (AMI) who were admitted to our 11 institutions between 1983 and 1988, examined by coronary arteriography and discharged alive, were followed for an average of 2.9 years. During the follow-up period, 212 patients (7.6%) died. The factors that governed the prognosis of myocardial infarction after discharge were advanced age, female gender, obesity, previous infarction, angina pectoris more than 1 month before the onset of AMI, post-infarction angina, multiple-vessel diseases, advanced stage by Killip's and/or Forrester's classification on admission, elevated pulmonary capillary arterial pressure, decreased cardiac index, decreased left ventricular ejection fraction, increased left ventricular end-diastolic volume and left ventricular aneurysm before hospital discharge. Patients with ventricular tachycardia or ventricular fibrillation during hospitalization showed a poor prognosis. In contrast, patients who received intracoronary thrombolysis, or emergent and/or elective percutaneous transluminal coronary angioplasty showed a favorable prognosis.

The seven countries study in Japan. Twenty-five-year experience in cardiovascular and all-causes deaths

Within the Seven Countries Study two Japanese cohorts of men aged 40-59 were enrolled, one from the farming village of Tanushimaru (n = 508) and the other from the fishing village of Ushibuka (n = 502), both located in Kyushu. Cardiovascular risk factors were measured at entry and 10 years later in the survivors. The 25-year death rate for all causes was 30% higher in Ushibuka than in Tanushimaru (p < 0.001) and higher also from specific causes except for violence. Baseline differences in the levels of age, blood pressure, serum cholesterol, smoking habits, body mass index and heart rate explained only 19% of the difference in all-cause mortality between the two towns. Multivariate models from data of the pooled cohorts showed that age was a significant predictor of coronary heart disease, stroke, cancer, all other causes and all-cause mortality. Cigarette smoking predicted coronary heart disease, cancer and all-cause mortality. Systolic blood pressure predicted coronary heart disease, stroke and all-cause mortality. Serum cholesterol, body mass index and heart rate predicted none of these five causes of death. Changes in systolic blood pressure during the first 10 years of follow-up were directly related to deaths between 10 and 25 years of follow-up, significantly improving the predictive power of the multivariate model. Changes in the other risk factors did not contribute, however, to improved prediction.

Factors governing re-infarction in patients with myocardial infarction in Japan

The subjects consisted of 2,733 patients with acute myocardial infarction (AMI) who were admitted to our 11 institutions between 1983 and 1988, examined by coronary arteriography, and discharged alive. The patients were followed for an average of 2.9 years after discharge. During the follow-up period, re-infarction occurred in 172 patients (6.3%). The factors associated with re-infarction were total cholesterol of more than 250 mg/dl, HDL-cholesterol of less than 35 mg/dl and diabetes mellitus. The rate of re-infarction was also high in patients who had had a previous infarction before admission, angina pectoris before or after the onset of AMI or multiple-vessel disease. In contrast, intracoronary thrombolysis reduced the rate of re-infarction.

Indium-111 antimyosin monoclonal antibody Fab imaging in patients with cardiomyopathy

Six patients with cardiomyopathy were imaged following intravenous injection of an indium-111 labeled monoclonal antibody directed against the heavy chain of cardiac myosin. Two patients had hypertrophic non-obstructive cardiomyopathy (HNCM), two patients had dilated cardiomyopathy (DCM), and two patients had specific heart muscle disease. One of 2 patients with HNCM and one of 2 patients with DCM had a positive antimyosin scan. The 2 patients with specific heart muscle disease manifested persistent blood pool activity of the antibody, thereby precluding interpretation of the images. The present report demonstrates that antimyosin antibody imaging may provide evidence of myocardial injury, or necrosis in some patients with cardiomyopathy.

Association of hyperinsulinemia and serum free fatty acids with serum high density lipoprotein-cholesterol

A total of 155 Japanese subjects (79 men and 76 women) who were classified as having normal or borderline glucose tolerance, according to the criteria for the 50-g oral glucose tolerance test (GTT) of the Japanese Diabetes Society, were analyzed for factors related to serum high density lipoprotein (HDL)-cholesterol concentration, especially the responses of insulin and free fatty acid (FFA) after a glucose challenge. In men, significant negative univariate correlations were observed with body mass index (P < 0.01), the summed values of triceps and subscapular skin-folds (P < 0.01), serum insulin concentration at all time intervals, and serum FFA at 30 and 60 min of GTT. Serum insulin at 60, 120, and 180 min, sum insulin, and FFA at 30 and 60 min of GTT were significantly related to serum HDL-cholesterol after adjustment for body mass index and triglyceride concentration. Multiple linear regression analysis with the step-forward method showed that sum insulin (P < 0.01), FFA at 60 min of GTT (P < 0.001), and alcohol consumption (P < 0.01) were independently related to serum HDL-cholesterol concentration. Only the triglyceride concentration was inversely correlated (P < 0.05) with HDL-cholesterol concentration in women. These data indicate that both insulin and FFA concentration, as markers of insulin resistance, apparently influence on HDL kinetics in men, but not in women. The lack of this association in women was appeared to related to the degree of obesity.

Neutrophil activation after percutaneous transluminal coronary angioplasty

We investigated whether percutaneous transluminal coronary angioplasty (PTCA) would induce neutrophil activation in patients with coronary artery disease. Blood samples were taken from the coronary sinus in 14 patients who underwent PTCA and in 9 control subjects who underwent coronary arteriography (CAG). Flow cytometry was used to measure membrane surface expression of beta 2 integrin (CD11b) and the generation of hydrogen peroxide in neutrophils after ex vivo phorbol myristate acetate stimulation by 2,'7'-dichlorofluorescein. Neutrophil elastase was measured by an immunoenzymatic method. Surface expression of CD11b increased significantly, approximately twofold, after PTCA but not after CAG. Mean fluorescence intensity of 2',7'-dichlorofluorescein in stimulated neutrophils decreased significantly after PTCA, suggesting a previous in vivo activation, but not after CAG. Neutrophil elastase increased significantly after PTCA but not after CAG. These data indicate that PTCA induces neutrophil activation and suggest that neutrophils may contribute to the ischemic injury.

Free oxygen radicals contribute to platelet aggregation and cyclic flow variations in stenosed and endothelium-injured canine coronary arteries

OBJECTIVES

The purpose of this study was to test the hypothesis that free oxygen radicals contribute to platelet aggregation and cyclic flow variations in stenosed and endothelium-injured coronary arteries.

BACKGROUND

Although free oxygen radicals, such as superoxide anion and hydrogen peroxide, have been shown to alter platelet function in vitro, the potential role of free oxygen radicals has not been fully described in an in vivo model of coronary artery thrombosis.

METHODS

Cyclic flow variations were produced in dogs by an external constrictor placed at the site of the left anterior descending coronary artery with injured endothelium. Blood flow in this artery was monitored by a pulsed Doppler flow probe. If cyclic flow variations were observed during postoperative days, dogs intravenously received superoxide dismutase plus catalase. In anesthetized dogs that did not develop an episode of cyclic flow variations, the effect of intracoronary infusion of xanthine plus xanthine oxidase or hydrogen peroxide on arterial blood flow velocity was studied. In platelet studies, the effect of free oxygen radicals and radical scavengers on platelet aggregation was examined.

RESULTS

In conscious dogs with cyclic flow variations, superoxide dismutase plus catalase significantly reduced cyclic flow variations (n = 7), whereas saline infusion had no effect (n = 7). The infusion of xanthine plus xanthine oxidase or hydrogen peroxide significantly induced cyclic flow variations in four of six dogs or in five of seven dogs, respectively. In vitro platelet studies showed that xanthine plus xanthine oxidase or hydrogen peroxide significantly enhanced platelet aggregation, and superoxide dismutase or catalase significantly inhibited such aggregation.

CONCLUSIONS

Reduction of free radical formation decreases platelet aggregation and may eliminate cyclic flow variations, whereas promotion of free radical generation enhances platelet aggregation and may induce cyclic flow variations. Thus, free oxygen radicals are an important mediator in this model.

[Detection and localization of multiple metastases from differentiated thyroid carcinoma with 99mTc-MIBI whole body scintigraphy: a case report]

A 79-year-old male with a history of total thyroidectomy due to follicular thyroid carcinoma developed multiple metastases in the lung, bone, and lymph nodes. In order to detect and localize every metastases, 99mTc-MIBI whole body scintigraphy was performed, and clearly depicted all metastatic lesions except tiny pulmonary nodules. 99mTc-MIBI whole body scintigraphy may be useful in detecting metastases from differentiated thyroid carcinoma, because of a good quality of scintigram and no need of patient preparation. This article is the first report on 99mTc-MIBI localization in multiple metastases from differentiated thyroid carcinoma.

A protease inhibitor, NCO-700, improves the contractile function in stunned canine myocardium

To explore the role of calcium-dependent protease in the stunned myocardium, open-chest dogs underwent 15 min of left anterior descending coronary artery occlusion followed by 2 h of reperfusion. Dogs received a single bolus intravenous injection of either the protease inhibitor NCO-700 (n = 6) or saline (n = 6) 1 min before reperfusion followed by a 30-min infusion at the same dose. Regional myocardial function was assessed in terms of systolic wall thickening with an epicardial Doppler probe. The two groups exhibited comparable systolic thickening under baseline conditions and similar degrees of dyskinesis during occlusion. After reperfusion, recovery of contractile function, expressed as a percentage of the baseline value, was significantly greater in NCO-700-treated dogs as than in control dogs: -14.3 +/- 10.6 vs -48.9 +/- 7.2 (p < 0.05) at 15 min, 10.8 +/- 10.3 vs -31.1 +/- 9.0 (p < 0.05) at 30 min, 42.5 +/- 10.1 vs -16.4 +/- 9.1 (p < 0.005) at 1 h, and 47.5 +/- 8.3 vs -14.9 +/- 9.4 (p < 0.001) at 2 h. The data suggest that the protease inhibitor markedly improved contractile function in stunned myocardium by inhibiting intracellular protease activity.

Hypertension induced by nitric oxide synthesis inhibition is renal nerve dependent

Recent studies have indicated that chronic administration of N omega-nitro-L-arginine methyl ester (L-NAME), an inhibitor of nitric oxide (NO) synthesis, produces marked hypertension. Although the mechanism of this form of hypertension is not well understood, several studies have demonstrated that sympathetic nerve activity is at least acutely elevated after L-NAME administration. To evaluate the potential role of the renal sympathetic nerves in L-NAME-induced hypertension, we compared the blood pressure response to L-NAME in four groups of Sprague-Dawley rats (n = 8 each): (1) sham-operated vehicle-treated, (2) sham-operated L-NAME-treated, (3) denervated vehicle-treated, and (4) denervated L-NAME-treated. After renal denervation or sham surgery, L-NAME was added to the drinking water (70 mg/100 mL) for 4 weeks, and arterial pressure was measured weekly by the tail-cuff method. L-NAME treatment caused a progressive increase in arterial pressure in sham-operated rats, rising to 154 +/- 6 mm Hg by week 4 of treatment compared with 115 +/- 2 mm Hg in the vehicle-treated sham-operated group (P < .005). In contrast, the development of hypertension was significantly delayed and attenuated in renal-denervated rats treated with L-NAME. The results of our study suggest that L-NAME-induced hypertension may be partly mediated by or is at least dependent on the integrity of the renal nerves.

Soluble form of P-selectin in patients with acute myocardial infarction

BACKGROUND

P-selectin, an integral membrane glycoprotein of platelets and endothelial cells, is rapidly redistributed to the cell surface after cellular activation. The soluble form of P-selectin has been shown to be present in people with normal circulation. The purpose of the present study was therefore to examine the soluble form of P-selectin in patients with acute myocardial infarction (AMI).

METHODS

Whole blood was obtained from nine patients with AMI and from 10 volunteers who made up the control group. Plasma concentrations of the soluble form of P-selectin were examined with a monoclonal antibody-based enzyme immunoassay.

RESULTS

Plasma P-selectin levels in control volunteers were 178 +/- 44 ng/ml. In patients with AMI, plasma P-selectin levels on days 1, 2 and 3 were 743 +/- 374, 627 +/- 267, and 588 +/- 223 ng/ml, respectively (P < 0.001)--significantly higher than the levels in the control volunteers.

CONCLUSION

Plasma concentrations of the soluble form of P-selectin were markedly higher in patients with AMI, suggesting the activation of platelets, or endothelial cells, or both. Thus, quantitative measurements of plasma P-selectin concentrations may help to assess the pathophysiology of inflammatory reactions in patients with AMI.

Possible gene dose effect of a mutant cardiac beta-myosin heavy chain gene on the clinical expression of familial hypertrophic cardiomyopathy

We have examined for a mutation in the cardiac beta myosin heavy chain gene from Japanese patients with familial hypertrophic cardiomyopathy. A missense mutation due to a G to A transition in codon 935, leading to a replacement of Glu with Lys, was found in one patient. Family members of this patient were then examined. It was revealed that both the proband and his elder brother, who was also a symptomatic patient, were homozygous for the mutation. The proband eventually died of intractable heart failure, and his brother died suddenly in their thirties. On the other hand, his parents, who were first cousins and heterozygous for the mutation, had cardiac hypertrophy without clinical symptoms. His elder sister was also heterozygous for the mutation, however, she did not manifest with cardiac hypertrophy. These observations suggest a gene-dose-like effect of the mutant cardiac beta myosin heavy chain gene on the clinical manifestation of familial hypertrophic cardiomyopathy.

Coronary artery disease trends in Japan

Japan has experienced great socioeconomic development together with industrialization, urbanization and motorization since 1945. This has resulted in dramatic changes in both the frequency of disease and the spectrum of diseases, as well as in a rapid increase in the elderly population. Changes in eating patterns during the past 40 to 50 years seem to be a major factor in this evolution. Departure from the traditional Japanese diet, which was very high in salt and low in fat and protein (currently the diet is 25% calories from fat, 60% from carbohydrate and 15% from protein and 12 gm salt/day), has been associated with a reduced incidence of stroke, but not with an increase in coronary heart disease mortality. Therefore, the current Japanese diet may be an optimal eating pattern for maintaining health. However, since the exposure to increased fat calories is recent, future trends must be carefully monitored.

Nonsurgical correction for thrombosis of a St. Jude Medical tricuspid prosthesis: report of a case

A 43-year-old woman with rheumatic heart disease underwent replacement of the aortic, mitral, and tricuspid valves using three SJM prostheses. Despite adequate warfarin therapy, routine cineradiography performed on the 40th postoperative day showed one of the leaflets of the tricuspid prosthesis to be "stuck" in the semiclosing position. A thrombosis of the tricuspid prosthesis was successfully treated with a urokinase infusion and mechanical thrombolysis using a pacemaker, following which normal valve function was restored.