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Biomedical subjects

F Zannad

Publications and source records attributed to F Zannad.

At least 145 records · Page 8Linked to original sources

[Blood hyperviscosity syndrome in essential arterial hypertension. Characterization and clinical effects].

Blood viscosity (BV) is one determinant of total arterial resistance (TAR) which is usually increased in hypertension. This increase is mainly related to vasoconstriction. In this study, we investigated the blood rheological properties in hypertension and their relation to blood pressure (BP) and left ventricular hypertrophy (LVH) since the latter could be related to increased TAR. BP and echocardiographic measurement of left ventricular mass (LVM) according to Devereux were measured and blood samples obtained from 22 untreated hypertensives aged 31 to 62 (13 men, 9 women) Control group consisted of 30 age-matched, normotensive blood donors. Results are shown in table I. (Formula: see text). A positive significant correlation was found between LVM and BV (r = 0.50; p less than 0.05) red cell filterability (r = 0.53; p less than 0.05) and red cell aggregability (r = 0.57; p less than 0.02). These results suggest that erythrocyte abnormalities are one of the determinants of the hyperviscosity syndrome in hypertension. Some variables of this syndrome were related to LVM and could therefore be among the determinants or a consequence of LVH in hypertensives.

Adult↗

The effects of amrinone on cardiac function, oxygen consumption and lactate production of an isolated, perfused, working guinea-pig heart.

Compared with isolated heart muscle and Langendorff preparations, the isolated, working heart preparation allows a more complete analysis of cardiac function and metabolism. We have studied the effects of amrinone 20 micrograms/ml and 200 micrograms/ml on the isolated perfused working guinea-pig heart. We have measured: heart rate (HR), mean systolic aortic pressure (SP), aortic flow (AF), coronary flow (CF), total cardiac output (CO), and calculated the stroke volume (SV) and the rate of external work (W). The rates of oxygen consumption (VO2) and lactate production (Lact) were also measured and the external efficiency (Eff) calculated. Hearts were allowed to fail spontaneously after work for 90 min. Amrinone was then added at the required concentration to the perfusion medium. Amrinone 20 micrograms/ml, increased AF, CF, CO, SV, W and VO2. HR was slightly but significantly increased. Lact and Eff were not altered. Amrinone 200 micrograms/ml substantially increased CF and VO2, but it increased slightly and not significantly AF, CO, SV and W, suggesting the predominance of the coronary vasodilating effect of amrinone at higher doses. Lact and Eff remained unchanged. The positive chronotropic effect was of the same magnitude than that observed with the lower dose. No arrhythmias occurred with either concentration. These results would suggest that amrinone is a positive inotropic drug with vasodilating properties at higher doses, and weak positive chronotropic effect. It stimulates aerobic but not anaerobic metabolism of the heart.

Aminopyridines↗

The effects of digoxin and dopamine on the oxygen consumption, lactate production and haemodynamic performance of an isolated, perfused, working guinea-pig heart.

We have adapted an established technique for perfusing the isolated, working rat heart to the guinea-pig heart and characterized its biochemical and haemodynamic performance. After 20 min of anoxia the heart recovers about 50% of its pre-anoxic performance ('post-anoxic cardiac failure') and after 90 min of continuous work total cardiac output falls to 50% of its initial, stable value ('spontaneous cardiac failure'). We have studied the effects of digoxin (10(-7) M and 2 x 10(-7) M) and dopamine (10(-5) M) on these two forms of cardiac failure and shown that digoxin improves the haemodynamic performance of the heart without altering its metabolism and therefore increases its efficiency. In contrast dopamine improves the haemodynamic performance of the heart at the expense of increased aerobic and anaerobic metabolism. The preparation is of value in studying the effects of cardioactive drugs on hearts subjected to constant pre-load and after-load.

Animals↗

Cation transport in erythrocytes of patients with renal failure.

Na+, K+-ATPase activity in erythrocytes (RBC) has been assessed indirectly by the 86Rb uptake method in 10 patients with acute renal failure (ARF), 11 patients with chronic renal failure (CRF) on haemodialysis and 13 patients treated by kidney transplantation, and compared to age-matched healthy controls. In each patients, the sensitivity of 86Rb uptake to digoxin (IC50) has been measured. Na+, K+-ATPase activity was decreased in patients with ARF and in patients with CRF but not in transplanted patients. IC50 was lowered in transplanted patients. The implications of these findings are discussed in terms of possible mechanisms of the changes in Na+, K+-ATPase activity in RBC of patients with renal failure.

Acute Kidney Injury↗

[Detection and quantification of left-to-right intracardiac shunts by angiocardioscintigraphy].

The ratio of pulmonary/systemic output (QP/QS) was measured by angioscintigraphy in 70 patients from 1 to 22 years of age (average 10 years) admitted to the Department of pediatric cardiology for a left-to-right shunt. Fifty nine of these patients underwent cardiac cathetarisation and QP/QS determination by oxymetry. The correlation between the values of QP/QS calculated by the two techniques was R = 0,83 (p less than 0,001: n = 59); in 28 cases of atrial septal defect R = 0,85; in 20 cases of ventricular septal defect, R = 0,75; in 11 cases of other left-to-right shunts, R = 0,79. No significant shunt was detected in 16 patients by oxymetry and the QP/QS ratio on angioscintigraphy was less than or equal to 1,2 except in 3 cases. In 7 cases of isolated pulmonary stenosis and 4 cases of operated septal defects no shunt could be detected by isotopic investigation. We conclude that angioscintigraphy is a reliable non-invasive method of detection and assessment of left-to-right shunts. In some cases it may avoid the necessity of cardiac catheterisation. The advantages, limitations and applications of this method are discussed.

Adolescent↗

Changes in 86-rubidium uptake in erythrocytes of digoxin-treated patients, in heart failure with sinus rhythm. Relationship to clinical effects.

Previous studies have shown a significant relationship between the clinical effect of digoxin and a tissue response, namely the inhibition of 86Rb uptake by the patients' erythrocytes. In the present study, this relationship is confirmed in patients, in heart failure with sinus rhythm. The slowing of the heart rate but not the QS2 index changes correlates significantly with the 86Rb uptake inhibition.

Adult↗

Digoxin in the elderly and in renal failure. Contribution of erythrocyte 86-rubidium uptake tests.

Na+,K+-ATPase activity was assessed indirectly in three groups of subjects of differing age, and in a group of patients with renal failure, by measuring the 86-rubidium uptake in the patients' own erythrocytes. The inhibiting action of digoxin on this activity was also measured in vitro. Erythrocyte 86Rb uptake was found to be lower in the elderly as was the calculated volume of distribution of digoxin. Sensitivity to the inhibiting action of digoxin increased with age. In the renal failure group 86Rb uptake was diminished and the sensitivity to digoxin was variable. This suggested that Na+,K+-ATPase activity could be one determinant of the volume of distribution of digoxin and that quantitative and qualitative changes of this enzyme could explain features of the pharmacokinetics of digoxin in renal failure and in old age.

Adult↗

Study of the sensitivity of neonates to digoxin: contribution of erythrocyte 86rubidium uptake test.

In general, there is little agreement how digoxin should be used in newborn, and the results of studies in this field seem contradictory. This study attempts a quantitative assessment of the number and the sensitivity of cellular receptors for digoxin in the organism, by the in vitro measurement of erythrocyte 86Rubidium uptake in neonates compared with adults and old people. Red blood cells are first incubated with differing concentrations of digoxin, and then incubated with 86Rb. The initial level of 86Rb uptake (Rbi) is that observed in the absence of digoxin. The 50% index of captation (IC50) is the digoxin concentration in nanograms per ml at which 86Rb uptake is half Rbi. Three groups of patients were studied: Group I: 12 neonates, less than 5 days old; Group II: 11 adults (26 to 57 years old); Group III: 9 elderly people (71 to 82 years old). Rbi was significantly lower in neonates (Mean +/- SD: 25.8% +/- 3.5, P less than 0.001) and in the elderly (29.9% +/- 3.1) than in adults (36.8% +/- 4.6). IC50 was significantly lower in the elderly (12.1 ng/ml +/- 2.4) than in the adult patients (20.5 ng/ml +/- 5.5, P less than 0.001). In the newborns, values of IC50 were widely scattered (16.2 ng/ml +/- 7.2). The authors suggest that since Rbi reflects Na+, K+-ATPase activity, this activity is diminished in newborn and old people, and indicates that they have fewer cellular receptors for digoxin than adults. In the elderly, the low IC50 would imply increased sensitivity to digoxin. In neonates, the wide range of values for IC50 suggests considerable individual variation in sensitivity to digoxin. The results are consistent with the recently recommended lower dosages of digoxin in neonates.

Adult↗

[Myocardial scintigraphy using technetium-99m labelled methylene diphosphonate in coronary care units. 82 cases].

Many isotopic methods have been proposed recently for the investigation of normal and diseased myocardium in ischaemic heart disease. The results of myocardial scintigraphy with Technetium 99 m marked methylene diphosphonate in the supine, left lateral and 30 degrees or 45 degrees right anterior oblique incidences are reported. A preliminary study of the tracer's fixation on diseased myocardium was performed in 18 patients. Scintigraphy every 30 minutes over a five hour period showed the optimal time for investigation to be situated between the third and fourth hour after the injection of the tracer. Seventy eight patients were then investigated; 82 scintigraphies were performed, 58 in patients with acute myocardial infarctions confirmed by the usual biological and electrocardiographic changes. A 74% sensitivity and 67% specificity were obtained with the methylene diphosphonate method. These figures varied according to the type of necrosis, subendocardial or transmural and with its extent, chronicity and degree of CPK elevation. Methylene diphosphonate scintigraphy would appear to be less sensitive and more specific for diseased myocardium than other isotopic methods. It may be carried out at the bedside and could improve the diagnosis of acute myocardial infarction when the clinical history and electrocardiographic changes are difficult to interpret.

Adult↗

Over 20 years' experience of beta-blockade in heart failure.

The use of beta-blocker therapy in heart failure was contraindicated for many years because it was considered to block necessary sympathetic compensatory responses to reduced cardiac function. However, early studies provided promising results in terms of improved symptoms and work capacity and reduced heart size. Small-scale studies have been completed over the past 20 years but until large-scale, long-term, randomized trials were conducted, the potential of beta-blockers in heart failure was not confirmed. The results of randomized trials published to date have included over 3,000 patients and the results show improvements in left ventricular function and heart rate. Significant improvements in New York Heart Association classification were also shown. Although no conclusive effect on mortality was shown, the first Cardiac Insufficiency Bisoprolol Study (CIBIS) indicated a trend toward improved survival during long-term treatment with bisoprolol. Ongoing studies have been specifically designed to investigate the effects of beta-blockers on survival. One of these trials, CIBIS II, which was terminated early in 1998 because of a positive effect on survival, is expected to report in late summer 1998. Such trials will also examine the different mechanisms of action of beta-blockers in heart failure and the influence of causes on the effects of beta-blockade.

Adrenergic beta-Antagonists↗

Effect of improved disease management strategies on hospital length of stay in the treatment of congestive heart failure.

Congestive heart failure (CHF) afflicts more than 4.6 million people in the United States and increases at a rate of 400,000 newly diagnosed patients per year. With more than 1.5 million hospital admissions per year attributed to CHF, it is the number one cause of hospitalization. Hospital length of stay (LOS) is one key determinant of greater hospital costs and has been the focus in some economic studies of CHF patients. In the present study, the potential economic benefits for hospitals from the implementation of improved disease-specific management programs in the treatment of CHF have been quantified in terms of LOS. We estimated the potential effects of disease management on LOS as a residual variation across hospitals, controlling for the effects of patient-specific characteristics, including severity of disease, health status, insurance status, and comorbidities. The study entry criteria and random sample selection yielded 5242 records for analysis. The average LOS was 7.1 days. The fixed effects or disease management practices across hospitals contribute to the explanatory power of the model by 4%. The 104 hospital-specific fixed effects measuring the potential impact of the differences in disease management relative to the reference hospital had values ranging from-3.41 to 4.33 days, for a total spread of 7.74 days, even after controlling for all other factors. The analysis suggests that the potential gain in profits for hospitals reimbursed on a per-case basis may be substantial, if disease management strategies practiced by those hospitals that lie to the left of the mean LOS were used by those that lie to the right of the mean LOS.

Aged↗

Nisoldipine coat-core and heart rate response during treatment of hypertension.

Nisoldipine coat-core (nisoldipine CC), an extended-release once-daily formulation, is an effective treatment for mild-to-moderate hypertension, providing sustained blood pressure control over the 24-hour dosing interval. Nisoldipine CC is highly vascular selective. It causes neither reflex tachycardia nor symptomatic bradycardia; it lacks significant negative inotropy at therapeutic doses; and it does not affect circadian variation in blood pressure or heart rate. Data suggest that the lack of reflex sympathetic activation in response to the blood pressure-lowering effect of nisoldipine CC is due to the smooth onset of action of nisoldipine CC, causing resetting of the baroflex. The neutral heart rate profile of nisoldipine CC confers potential therapeutic advantages over several other calcium channel blockers, in particular, the short-acting agents, in the treatment of hypertension.

Adrenergic beta-Antagonists↗

[Management, cost and mortality of a cohort of patients with advanced heart failure (the EPICAL study)].

The objectives of this study are to describe the management, outcomes and costs of patients with severe chronic heart failure (CHF) and to identify the associated socio-demographic and clinical determinants. In 1994, the EPICAL study enrolled in a French region a representative cohort of 358 patients presenting for the first time with severe CHF (NYHA class III or IV) requiring hospitalization. The mean annual cost per patient was 125 652 FF, 92.6 per cent of which was associated with in-patient care including the index hospitalization. Ten per cent of patients contributed 33 per cent of the total cumulative costs. The rate of readmission was very high (20 per cent per month of follow-up) and appeared as a major cost driver. Three variables were identified in a multivariate logistic regression as the main contributors to cost: the presence of co-morbidity, renal insufficiency and marital status (living alone versus with spouse). These findings confirmed the major clinical and economic interest of any intervention that could lower the rate of readmissions in this group of patients.

Adult↗

[Difficulties with conducting clinical trials in France].

France ranks third among European countries as regards the level of investment in clinical R&D and, overall, accounts for a contributive effort proportional to the size of its population and pharmaceutical market respectively. However, there is a trend for phase II and III studies to become proportionally fewer than in the past, while the number of phase IV studies is increasing. In a growing proportion of the mega-trials, which are instrumental for establishing evidence-based practice, French experts, investigators and, even more seriously, French patients, are insufficiently represented. Though studies in France are initiated relatively fast due to a clear regulatory framework and perform equally well as far as quantitative and qualitative factors are concerned, compared with most European countries involved in clinical research the costs incurred per completed patient are higher than those recorded in the other countries. Academic research shares most of these constraints and suffers from a lack of financial and human resources, while it faces additional delays in implementing studies because of longer administrative processes. Given the stakes in play, specific solutions should be implemented to maintain and further develop French competitiveness in clinical R&D. At the patient level, positive perception and awareness of the usefulness and safety of participating in clinical trials need to be emphasized. Education at the school level and using the lay media should be developed. Intervention of institutional and government officials is much needed. Direct patient recruitment should be developed through advertisement and the Internet, as well as within doctors' offices and through collaboration with patients' organizations. Patient information and consent forms should be made much simpler than those imposed within the framework of global studies because of FDA requirements. The French health system discourages the recruitment of patients by investigators who are not the family doctor or the usual care provider. Thus, motivation and education of general practitioners and hospital doctors may be increased by involving them during the trial design phase and in the publication process. Specific administrative solutions, within private or public institutions, need to be developed for investigators who do not personally wish to receive investigation fees. Because of lack of availability, investigators need to be assisted with study nurse services and site management organizations, particularly within hospitals and clinics, using the model of the Clinical Investigation Centres. Networks of clinical investigation centres and of individual investigators need to be created. Implementing these solutions should lead to better implications for and reputation of French clinical research.

Clinical Trials as Topic↗

[Pharmacologic limitation of the size of the myocardial infarction (excluding thrombolysis)].

Several pharmacological agents possess cardio-protective properties. Some of these agents have been evaluated in the context of the limitation of the size of the myocardial infarction. In this study, controlled randomised trials evaluated the effects of a solution of glucose-insulin-potassium (GIK), hyaluronidase, nitrate derivatives, calcium antagonists and beta-blockers administered during the first few hours following acute myocardial infarction. Despite promising results, we do not yet have any proof of the effectiveness of the GIK solution, hyaluronidase or nitrate derivatives. Nifedipine appears to be devoid of any effect and other calcium antagonists are currently under investigation. The numerous trials have been performed with beta-blockers generally support their beneficial effect on the limitation of the size of the infarction, which is usually accompanied by a reduction in the mid and long term mortality. They are therefore recommended in this indication and their practical use is discussed.

Adrenergic beta-Antagonists↗