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Biomedical subjects

R Dietz

Publications and source records attributed to R Dietz.

At least 199 records · Page 11Linked to original sources
PubMed1991

Modulation of coronary circulation and the cardiac matrix by the renin-angiotensin system.

There are short-term and long-term modulations of cardiac function and cardiac composition by the endocrine and paracrine renin-angiotensin system. First, there is an enhancement of coronary vasoconstrictor tone in severe congestive heart failure due to stimulation of this system. Therapeutic interventions that block the RA-system are able to reduce the increased resistance to coronary flow. Second, there is a relationship between the occurrence of arrhythmias and the degree of sympathetic stimulation in congestive heart failure. The renin-angiotensin system may be involved in arrhythmogenesis because of presynaptic modulation of sympathetic neurotransmitter release. However, in the isolated perfused rat heart no class-specific antiarrhythmic properties could be found for ACE inhibitors during progressive myocardial ischaemia. Third, proliferation of the neointima following injury of a coronary artery is at least in part mediated by angiotensin II. Although ACE inhibition was an effective tool in animal experiments to prevent excessive proliferation of the neointima following ballooning, it was less effective in preventing restenosis in man following a repeat coronary angioplasty. Fourth, preferential proliferation of the cardiac interstitium in experimental hypertension has been associated with activation of the renin-angiotensin system. In patients with essential hypertension ACE inhibitors were not only capable of controlling blood pressure but also of normalizing the previously pathological pattern of diastolic left ventricular filling. In summary, by therapeutic intervention that cause a blockade of this system, cardioprotective and cardioreparative processes can be supported.

Angiotensin II↗
PubMed1991

Improvement of diastolic filling in hypertensive patients treated with cilazapril.

The aim of this study was to assess the behavior of the diastolic left ventricular (LV) filling pattern and cardiac hypertrophy after treatment with cilazapril. Twelve patients (9 male and 3 female) with mild to moderate essential hypertension, aged 46 +/- 14.1 years, were treated with cilazapril for 1 year. They underwent Doppler echocardiography at the beginning (I), after 6 months (II), and after 1 year (III) of treatment. The following parameters were evaluated: mean arterial pressure (MAP) automatically recorded for 24 h, interventricular septal and posterior wall thickness, LV and end-diastolic diameter, LV mass index, early (E) and late (A) diastolic filling flow velocities, and the ratio E/A. A significant reduction in LV hypertrophy and an improved diastolic filling pattern of the left ventricle was shown after 6 months of therapy with cilazapril; this improvement still remained after 1 year of therapy.

Adult↗
PubMed1991

Circadian rhythm of blood pressure in congestive heart failure and effects of ACE inhibitors.

In 33 patients with heart failure (NYHA II-III), the 24-h blood pressure rhythm was examined before and after the titration period of two ACE inhibitors. Blood pressure was measured by the oscillometric method using the blood pressure monitor 90202 from SpaceLabs, Inc. The measurements were taken from 06:00 to 22:00 h every 20 min and from 22:00 to 06:00 h every hour. Patients were randomized to therapy with either captopril (group 1, n = 17) or enalapril (group 2, n = 16). The average daily dosage of captopril was 41 +/- 3 mg given in three divided doses (08:00, 12:00, and 17:00 h). The mean dose of enalapril was 8 +/- 1 mg once daily (08:00 h). Serum electrolytes, serum creatinine, and plasma renin activity were measured before and during therapy with both ACE inhibitors. Twenty-four-hour blood pressure measurements were taken before and on the fifth day of treatment with ACE inhibitors. Both groups were not different with respect to the degree of heart failure, the concomitant medication, and the 24-h profiles of blood pressure and heart rate before initiation of ACE inhibition. The 24-h blood pressure values on day 5 were consistently below the pretreatment values (p less than 0.005) in both groups. Both groups did not differ significantly during ACE inhibition in their 24-h blood pressure and heart rate profiles. In both groups, the mesor of the systolic and diastolic blood pressure decreased significantly by the same degree (by 4.7/5.1 mmg Hg in group 1 and 6.4/4.1 mm Hg in group 2). The systolic/diastolic blood pressure amplitude decreased slightly in both groups. Before treatment, serum sodium, potassium, and creatinine were within the normal range. The increase in potassium (0.5 +/- 0.1 mmol/L) reached statistical significance (p less than 0.01) only in the captopril group, whereas it was not significant in the enalapril group (0.1 +/- 0.1 mmol/L). Serum creatinine was not significantly altered by both ACE inhibitors. No relationship could be found between the changes in serum potassium or creatinine and the mean of the 24-h blood pressure values during ACE inhibition. Captopril and enalapril showed comparable blood pressure profiles and similar effects on renal function at the end of the titration on day 5. It can therefore be concluded that the effects on blood pressure rhythm and renal function are similar with a single daily dose of enalapril compared to captopril given three times daily.

Blood Pressure↗
PubMed1991

[Malignant cystosarcoma phyllodes].

In this paper we report a case of cystosarcoma phyllodes malignum in a 45 years old female patient. A local relapse occurred 20 months after ablatio mammae. This tumor was histologically a benign fibroadenoma. 69 months postoperative metastases of the pleural diaphragma were found: the appearance was similar to that of a mesothelioma. The CEA was helpful in revealing the metastases and in indicating the progression. This case is discussed and compared to the review of the literature. Because of the high rate of local relapses a postoperative irradiation of the chest wall is proposed.

Breast Neoplasms↗
PubMed1991

[Role of the sympathetic nervous system in heart failure].

An increased activity of the sympathetic nervous system has been regarded as a sensible compensatory mechanism in heart failure. Further stimulation of this system by therapeutic interventions has proven useful in the situation of acute heart failure; however, the contractile reserve elicited by beta-stimulation is markedly reduced. By long-term stimulation of the sympathetic nervous system in the treatment of chronic heart failure mostly unfavorable effects are evoked, i.e.: 1) An increase in impedance for the failing heart by stimulation of peripheral alpha 1-adrenoreceptors. 2) An increase in myocardial oxygen consumption which causes further deterioration of the energy balance in the failing heart. 3) A fall in serum potassium concentration by stimulation of beta 2-receptors combined with a reduction of the fibrillation threshold favor the genesis of malignant arrhythmias. 4) Stimulation of myocardial alpha 1-adrenoreceptors may lead to a de-differentiation with a preferential synthesis of fetal myosins. Because of a reduced rate of calcium removal during diastole, increases in heart rate lead to an elevated myocardial stiffness. An increased sympathetic activity in patients with heart failure represents an independent marker of a reduced life expectancy. Interventions that either cause a reduction in sympathetic activity or which protect the heart from high catecholamine concentrations in heart failure are associated with an improvement of survival and quality of life.

Heart Failure↗
PubMed1991

[ACE inhibition: mechanisms of cardioprotection in chronic heart failure].

In the treatment of heart failure ACE inhibitors gained a unique position because of their beneficial effect on prognosis. The most likely explanation is their influence on factors that determine progression of the disease. These are: progressive deterioration of central hemodynamics, impairment of coronary perfusion, further activation of vasopressor systems, imbalance of sodium and water homeostasis and occurrence of malignant arrhythmias. ACE inhibitors have been shown to modulate these factors in a positive manner. In addition, they may also act by modulating factors, which may exert harmful effects on cardiac function in long term. These are: prevention and regression of the hypertrophy of the left ventricle as well as the media of resistance vessels, prevention of restenosis following PTCA, prevention of cyclosporin-induced premature coronary artery sclerosis, and correction of an impaired glucose metabolism. Whereas the positive effects of ACE inhibitors in the treatment of heart failure are well documented, their value for preventing heart failure has not been established, yet.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1991

[Comparative studies on immunomodulation via hyperfractionated whole-body irradiation].

The effect of the humoral immune response on Sprague-Dawley rats by hyperfractionated total body irradiation was investigated. These experiments included single doses of total body irradiation (1 Gy, 2 Gy, 3 Gy) and the administration of 1 Gy and 2 Gy in two or three fractions 2 x 0.5 Gy, 3 x 0.33 Gy and 2 x 1.0 Gy, 3 x 0.66 Gy. The time between the fractions was six hours. The primary production of antibodies against erythrocytes of sheep were determined as immunity parameter. The immune stimulation could be achieved, when single doses of 1 or 2 Gy were delivered. The single dose of 3 Gy total body irradiation showed a small, not significant immunosuppression. A significant immunosuppression was observed in all our hyperfractionated experiments. The degree of immunosuppression was nearly equivalent in the hyperfractionated group (2 x 0.5, 3 x 0.33 Gy and 2 x 1.0, 3 x 0.66 Gy).

Animals↗
PubMed1991

[CT diagnosis of inferior vena cava anomalies. The azygos continuation].

The azygos continuation is a rare variation of the inferior vena cava (IVC), usually associated with cardiac anomalies. We report CT in two female patients with no cardiac disease. One had no further visceral abnormalities, while the other had polysplenia agenesis of the left lobe and a hypertrophic right lobe of the liver. This complex of anomalies has been demonstrated for the first time by imaging. Our cases show the variation of anomalies associated with azygos continuation. When planning therapeutic procedures (for example cava filtration) these anomalies are relevant. CT is sufficient for their demonstration and in most cases there is no need for confirmation by invasive methods.

Adult↗
PubMed1991

[Enalapril versus captopril in heart failure--effect on blood pressure and kidney function].

In 33 patients with heart failure (NYHA II-III) the 24-h blood pressure was examined during the titration of two ACE-inhibitors. Blood pressure was measured by the oscillometric method using the blood pressure monitor 90202 from SpaceLabs, Inc.. All patients received an additional therapy either with captopril (group A, n = 17) or enalapril (group B, n = 16) in random order. Serum-electrolytes, serum- and urine-creatinine, and plasma-renin- activity were measured before and during therapy with both ACE-inhibitors. 24-h blood pressure measurements were taken before and on the first and fifth days of the treatment with ACE-inhibitors. Neither group was different with respect to the degree of heart failure, the concomitant medication, and the 24-h profiles of blood pressure and heart rate. The mean initial dose of captopril was 9.2 +/- 1.2 mg which was titrated to a mean daily dose of 40.7 +/- 3.3 mg given three-times daily. Each patient of group B received an initial dose of 2.5 mg enalapril and a mean maintenance dose of 8.4 +/- 0.9 mg once daily. The first dose effect on blood pressure was similar with captopril and enalapril with a maximal decrease of systolic and diastolic blood pressure of 8/8 mmHg (after 1 h) in group A and of 9/7 mmHg (after 4 h) in group B. The 24-h blood pressure values on day 5 were consistently below the pretreatment values (p less than 0.005) but heart rate was not significantly affected by either ACE-inhibitor. Neither group differed significantly during ACE-inhibition in their 24-h blood pressure and heart rate profiles.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Pressure↗
PubMed1990

Plasma concentrations of atrial natriuretic peptide during physical exercise in patients with congestive heart failure.

Plasma concentrations of atrial natriuretic peptide (ANP) were measured in 25 patients with organic heart disease during physical exercise (baseline and maximum workload) in order to investigate if the responsiveness of stimulated release of ANP is still preserved in patients with heart failure and chronically elevated cardiac filling pressures. Since plasma concentrations of ANP are known to be positively correlated with mean right atrial pressures (RAP), the patients were divided into two groups according to their resting RAP; group I; those with normal RAP (less than or equal to 5 mmHg; n = 11); group II; those with elevated RAP (greater than 5 mmHg; n = 14). Under baseline conditions RAP (3.2 +/- 0.4 mmHg vs. 8.8 +/- 0.7 mmHg; p less than 0.01), pulmonary artery diastolic pressure (PADP; 9.5 +/- 0.9 mmHg vs. 17.9 +/- 1.8 pg/ml; p less than 0.01), and plasma ANP levels (128 +/- 19 pg/ml vs. 204 +/- 60 pg/ml; p less than 0.06) were significantly lower in group I than in group II. Both at rest and during maximum workload, plasma ANP concentrations were closely related to RAP, PADP, and mean pulmonary artery pressures in both groups. During exercise in all patients, RAP and PADP significantly increased, as well as plasma ANP concentrations. Similar increments in plasma ANP concentrations were accompanied by greater changes in RAP in group II than in group I. However, identical changes in PADP lead to identical increments in plasma ANP concentrations in both groups. In conclusion, the increments of plasma ANP concentrations during physical exercise were independent of the resting values of PADP, RAP, and plasma ANP concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Distributional pattern of zinc, cadmium, mercury, and selenium in livers of hooded seal (Cystophora cristata).

The liver of Hooded Seal (Cystophora cristata) consists of six lobes of unequal sizes. Extensive sampling by means of cutout samples covering the depth horizon 2-30 mm below liver surface indicates that the liver may be considered homogeneous as to concentrations of zinc, cadmium, mercury, and selenium (residuals of overall mean compatible with normality, the all-organ variance negligibly in excess of within-lobe variance). Mercury and selenium are present in equimolar concentrations. Cutout samples have mercury and selenium concentrations respectively c. 17 and 8% (dry weight basis) above those of homogenates of the same lobe. The apparent dilution of mercury and selenium is tentatively attributed to coarse blood vessels and bile ducts abundantly present in the homogenate but almost absent from the cutouts.

Animals↗
PubMed1990

ACE inhibition improves vagal reactivity in patients with heart failure.

The deranged autonomic control of heart rate was studied in 34 patients with heart failure (New York Heart Association [NYHA] functional class II to III) by examining the carotid sinus baroreflex. The carotid sinus baroreceptors were stimulated by graded suction. The slope of the regression line between increases in cycle length and the degree of neck suction was taken as an index of baroreflex sensitivity. The reflex response is mediated by a selective increase of vagal efferent activity. Baroreflex sensitivity therefore represents a measure of vagal reactivity. Using multiple regression analysis, baroreflex sensitivity (BS) correlated positively to stroke volume index (SVI) and inversely to plasma renin activity (PRA) and to age: BS = 0.47 SVI - 0.38 PRA - 0.23 age + constant (r = 0.74; p less than 0.0005). In addition to digitalis and diuretics, angiotensin-converting enzyme (ACE) inhibitors (captopril or enalapril) were given to 16 patients for a mean of 17 +/- 3 days. The patients with hemodynamic improvement (group A) exhibited improved baroreflex sensitivity (1.4 +/- 0.4 to 3.6 +/- 1.2 msec/mm Hg; p less than 0.01). Baroreflex sensitivity remained unchanged (3.1 +/- 0.8 to 2.4 +/- 1.0 msec/mm Hg; n.s.) in the patients without hemodynamic improvement (group B). The increase in reflex sensitivity did not correlate with hemodynamic alterations. Baroreflex sensitivity during ACE inhibition (BSD) was only related to the baseline baroreflex sensitivity (BSB): BSD = 2.8 BSB - 0.46 (r = 0.84; p less than 0.005). In patients with heart failure, reflex bradycardia decreases with age and with PRA and increases with stroke volume. Chronic therapy with ACE inhibitors enhances vagal reactivity in patients with hemodynamic improvement.

Adult↗
PubMed1990

Organic mercury in Greenland birds and mammals.

Muscle, liver and kidney samples of 20 species of birds, seals, whales and polar bear were analyzed for total and organic mercury. Organic mercury concentrations varied considerably between individuals. A general tendency towards age accumulation was found, together with log-linear correlations between organic mercury concentrations in the three tissues. The major part of the muscle mercury was organic (maximum concentration found was 1235 micrograms kg-1 wet wt). This also applied to liver of birds, while in mammal liver organic mercury concentrations approached a level of 2000 micrograms kg-1 wet wt, which was not exceeded even when the total mercury concentration was greater than 100,000 micrograms kg-1 wet wt. The percentage of organic mercury in relation to total mercury in kidney of seals and whales was 10-20% (maximum 982 micrograms organic mercury kg-1 wet wt), while in polar bear it was less than 6% (maximum 217 micrograms kg-1 wet wt). For the monitoring of local food in the Arctic, the simpler and less expensive analysis of total mercury suffices when testing muscle, whereas liver and kidney should be tested for organic mercury as well.

Animals↗
PubMed1990

Atrial natriuretic peptide mRNA in patients with heart disease.

The regulation of atrial natriuretic peptide (ANP) synthesis within cardiac atrial myocytes was investigated in 8 patients undergoing cardiac surgery (valve replacement or coronary bypass graft). Hemodynamic data were obtained during cardiac catheterization and venous plasma samples for ANP were withdrawn prior to surgery. Probes for determination of tissue ANP levels and ANPmRNA concentrations were taken from the right atrium. Both plasma ANP (r = 0.75; P less than .05) and ANPmRNA (r = 0.86; P less than .01) were closely related to mean pulmonary artery pressure. ANPmRNA was also related to plasma ANP (r = 0.60; P less than .07). However, no significant relationships were obtained between either plasma ANP or ANPmRNA and right atrial ANP concentrations. These data suggest that right atrial ANP synthesis is regulated by cardiac filling pressures and possibly by plasma ANP levels, independent from corresponding ANP tissue concentrations.

Aged↗
PubMed1990

Intravenous carbochromen: a potent and effective drug for estimation of coronary dilatory capacity.

Systemic and coronary haemodynamic effects of carbochromen (0.125 mg kg-1 min-1 for 40 min i.v.) and dipyridamole (0.05 mg kg-1 min-1 for 10 min i.v.) were investigated in 18 patients without detectable heart disease. Both drugs induced a comparable increase in coronary blood flow (carbochromen: from 82 +/- 23 to 337 +/- 68 ml.100 g-1.min-1; dipyridamole: from 78 +/- 9 to 301 +/- 61 ml.100 g-1.min-1). This resulted in a minimal coronary resistance of 0.23 +/- 0.04 mmHg.ml-1.100 g.min for dipyridamole and of 0.24 +/- 0.04 mmHg.ml-1.100 g.min for carbochromen. In response to dipyridamole (n = 12) heart rate increased from 73 to 94 beats min-1 (P less than 0.005) and mean aortic pressure fell from 89 to 78 mmHg (P less than 0.001). After administration of carbochromen (n = 6) no significant systemic effects occurred. Dipyridamole induced a significant increase in myocardial oxygen consumption by 46% (P less than 0.001); after application of carbochromen myocardial oxygen consumption remained unchanged. From these data it can be concluded that for the evaluation of coronary dilatory capacity carbochromen may be more suitable than dipyridamole because (1) maximal coronary vasodilation is induced without changes in myocardial oxygen consumption and (2) no systemic effects occur.

Adult↗
PubMed1990

Haemodynamic changes caused by alteration of autonomic activity in patients with heart failure.

In 14 patients with heart failure (New York Heart Association class 2-3) and sinus rhythm the carotid sinus baroreceptors were stimulated to induce a reflex mediated decrease of sympathetic efferent activity and a simultaneous increase in vagal tone. Five patients were in severe heart failure (New York Heart Association class 3) with raised plasma concentrations of noradrenaline at rest (2.99 (0.86) nmol/l (mean (SD)) and nine patients had less severe heart failure (class 2.2 (0.2)) and normal plasma concentrations of noradrenaline at rest. The haemodynamic responses during arterial baroreceptor stimulation were different in both groups. In all five patients with severe heart failure cardiac output increased whereas in the nine patients with less severe heart failure it was unchanged or decreased. The increase of cardiac output in the group with severe heart failure was solely the result of a significant increase of stroke volume index (by 9 (2) ml/m2). In the nine patients with less severe heart failure stroke volume remained unchanged but heart rate decreased significantly by 7 (2) beats/min during baroreceptor stimulation. These data show that an integrated change of autonomic activity consisting of a decrease in sympathetic tone and an increase in vagal activity leads to an increase of stroke volume in patients with severe heart failure and hence to haemodynamic improvement.

Adult↗