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Biomedical subjects

D Duprez

Publications and source records attributed to D Duprez.

At least 109 records · Page 6Linked to original sources
PubMed1990

Investigation of possible pharmacokinetic and pharmacodynamic interactions between epanolol and digoxin.

The possibility of a pharmacokinetic and/or pharmacodynamic interaction between epanolol and digoxin has been investigated in 10 healthy male subjects taking digoxin 0.375 mg daily for 14 days. During that period epanolol 200 mg daily or matching placebo was also given, each for 7 days, according to a double-blind, randomized cross-over plan. The plasma digoxin concentration-time profiles after 7 days of concomitant placebo or epanolol were comparable. Trough and peak plasma digoxin levels were similar (placebo: 0.84 and 2.62 ng.ml-1; epanolol: 0.87 and 2.46 ng.ml-1). The renal clearances of digoxin and creatinine were lower during treatment with epanolol, but the differences were not significant (placebo 142.0 and 126.5 ml.min-1; epanolol 105.7 and 109.3 ml.min-1). STI indexes were lower during treatment with digoxin plus epanolol, than after digoxin alone. The difference was significant for QS2I (513 versus 503 ms), PEPI (119 versus 112 ms) and PEP/LVET (0.286 versus 0.304). The observations suggest that in healthy volunteers there is no pharmacokinetic interaction between epanolol and digoxin, and that epanolol does not interfere with the positive inotropic action of digoxin.

Adrenergic beta-Antagonists↗
PubMed1990

Isolated rheumatic carditis, a disease in search of diagnostic criteria.

We report a case of acute dilated cardiomyopathy with histologic proof of inflammatory myocarditis. Although immunosuppressive therapy seemed to induce the resolution of the inflammatory infiltrate, it had no effect on the clinical course. The diagnosis of isolated rheumatic carditis was considered because of the finding of a very high antistreptolysin O titre and lack of evidence for either viral disease, infection with group C and G streptococci or other causes of spuriously high titres of anti-streptolysin O. In view of our conclusion longterm chemoprophylaxis was instituted.

Adult↗
PubMed1990

Hypertension due to a renal renin-secreting tumour.

We report a case of a 25 year old man referred to our department because of a blood pressure of 162/122 mmHg, found during a general physical examination. A renal renin-secreting tumour was found to be the cause of the hypertension. It had a diameter of 4 cm and was enucleated from the right kidney. Subsequently the blood pressure returned to normal levels. Histological examination revealed a hemangiopericytoma.

Adult↗
PubMed1989

Identification of a new heparin-binding protein localized within chick basement membranes.

A protein with a molecular mass of 19 kDa has been purified to homogeneity from 11-day-old chick embryos using a procedure involving chromatography on heparin - Sepharose, immunoaffinity resin and C4 reversed-phase. Indirect immunofluorescence studies, using polyclonal and monoclonal antibodies raised against this protein, indicate that it is essentially localized within the basement membranes in early embryonic tissues. After the 18th day of embryonic life and in post-hatched chicken, this protein could only be detected in some eye basement membranes. It appears to be bound to heparan sulfate chains of the proteoglycan present in these structures. Thus, the protein exhibits similar properties to those previously described for fibroblast growth factors (FGF), such as heparin affinity, molecular mass and localization in the basement membranes. In contrast, this protein is present in much larger amounts than FGFs, at least in 11-day-old embryos. Furthermore, the first 17 amino acid residues of the N-terminal sequence show that it does not strictly correspond to any previously described protein.

Amino Acid Sequence↗
PubMed1989

Interplay and interference of the carotid baroreceptors, central command, ergoreceptors on the peripheral vascular responses during static exercise.

1. The aim of the present study was to examine the influence of the carotid baroreceptors on the peripheral vascular responses during static exercise and its interference with the 'central command' and the ergoreceptors. 2. Ten healthy subjects performed an isometric handgrip with 30% of maximal voluntary contraction for 1.5 min. Five seconds prior to the end of the exercise the arterial circulation to the exercising forearm muscles was occluded for 1.5 min. The carotid baroreceptors were stimulated by neck suction at -40 mmHg for 0.5 min in each period, and also during control and recovery phase. Contralateral forearm and calf blood flow were measured simultaneously with ECG-triggered venous occlusion plethysmography. 3. The present findings suggest that there are 'central command' and ergoreceptors which modulate carotid baroreflex function to the afferent output to the heart and the peripheral circulation.

Adult↗
PubMed1989

Non-invasive diagnosis of carotid artery disease.

Non-invasive carotid evaluation has been developed in an effort to delineate safely the pathological anatomy and hemodynamic effects of carotid atherosclerotic disease. Non-invasive tests can be divided into direct tests which examine the hemodynamics. Following tests are considered as indirect tests: ophthalmodynamometry, doppler examination, oculoplethysmography and as direct tests: phonoangiography, Doppler ultrasound en Duplex scanning. A combination of a direct and indirect test will augment the sensitivity and specificity of the evaluation of carotid artery disease.

Angiography↗
PubMed1989

The role of the endothelium on calcium-entry blockade in coronary vasospasm.

Calcium-entry blockers are widely used for the treatment of coronary vasospasm. The mechanisms responsible for coronary vasospasm are still uncertain, but ultimately involve contraction of the vascular smooth muscle of the large coronary artery. The direct constrictor responses of coronary smooth muscle can be reduced by the inhibitory effect of endothelium-derived relaxing factor(s). The absence of endothelium can augment the response of vascular smooth muscle to vasoconstrictor stimuli, but may also modify the potency of calcium-entry blockers. The role of calcium-entry blockers on the endothelial function is not known. Nisoldipine is a new compound from a series of calcium-antagonistic dihydropyridines. The aim of the present experiments was: 1. to determine the effect of nisoldipine on contractions of large coronary arteries evoked by possible mediators of coronary vasospasm and 2. to determine whether or not the presence of endothelial cells affects the response to the calcium-entry blockers. Rings of canine coronary arteries with and without endothelium were studied in organ chambers filled with modified Krebs-Ringer bicarbonate solution. The rings were incubated for 45 min either in control solution or in the presence of increasing concentrations of nisoldipine (10(-10) to 10(-6) M). In the concentration range of 10(-9) to 10(-7) M nisoldipine inhibited the contractile responses evoked by allagents: KCL (10 to 80 mM), 5-hydroxytryptamine (10(-9) to 10(-6) M), ergonovine (10(-9) to 10(-6) M), norepinephrine and phenylephrine (10(-9) to 10(-4) M both in the presence of propranolol 5 X 10(-6) M). Nisoldipine was more potent in inhibiting contractions to potassium chloride in the absence of the endothelium. By contrast, in case of 5-hydroxytryptamine or phenylephrine, nisoldipine was less potent in the absence of the endothelium. Similar results were obtained in the case of ergonovine and norepinephrine. The hypoxic contractions were reduced by nisoldipine in a concentration dependent manner. Nisoldipine inhibited the platelet-induced contractions both in the presence and the absence of endothelium. The present study demonstrates that the dihydropyridine, nisoldipine, is a potent inhibitor of contractions of the smooth muscle of large coronary arteries caused by a number of putative mediators of coronary vasospasm including catecholamines and products released by aggregating platelets. It also prevents hypoxic contractions of coronary vascular smooth muscle.

Animals↗
PubMed1989

Relapsing digital ulcers.

A 72-years-old male patient is described who presented with relapsing, digital ulcers on both feet, accompanied by digital cyanosis ("purple toes"). All episodes occurred 5 months after starting coumarin treatment for chronic atrial fibrillation and low output failure. Massive mural thrombosis was discovered of the entire abdominal aorta. Because of the clinical picture, together with progressive renal failure and persistent eosinophilia, cholesterol embolization from an ulcerated atherosclerotic plaque within the mural thrombus was highly suspected. Besides the clinical presentation of our patient, the spectrum of cholesterol embolization is much wider. The role of coumarin therapy is still speculative. Numerous reports however, indicate a potential role in precipitating the syndrome. The only therapy available consists of removing the source whenever possible.

Aged↗
PubMed1987

Peripheral vascular responses during carotid baroreceptor stimulation in normotensive and hypertensive subjects.

1. The carotid baroreceptors were stimulated for 2 min by neck suction at -30 and -60 mmHg in 19 normotensive subjects and 12 patients with moderate essential hypertension. 2. Blood pressure was measured with a mercury sphygmomanometer and heart rate was derived from beat-to-beat analysis of the electrocardiogram. Blood flow was measured simultaneously at calf and finger with venous occlusion plethysmography and the vascular resistance was calculated. 3. During neck suction at -30 and -60 mmHg there was a significant decrease in arterial blood pressure and heart rate. There was a transient vasodilatation of the calf blood vessels, while there was a sustained vasoconstriction of the finger blood vessels. These results were qualitatively similar in both groups; however, there were quantitative differences. 4. These experiments show that there is a selective autonomic control of the different peripheral vascular beds by the carotid baroreceptors in both normotension and mild essential hypertension.

Adult↗
PubMed1987

Effect of ketanserin in the treatment of patients with intermittent claudication: results from 13 placebo-controlled parallel group studies.

The effect of ketanserin on intermittent claudication was assessed in 13 placebo-controlled parallel group studies following basically the same protocol. After a single-blind placebo run-in period of 1-2 months, the patients randomly received either ketanserin (n = 152) or placebo (n = 158) for 3-6 months. Data on walking distance, assessed on the treadmill, were available in 12 centers (239 patients). Walking distance significantly increased in seven centers with ketanserin and in two centers with placebo. In two centers, the intergroup comparison between ketanserin and placebo was significantly in favor of ketanserin; in one center, it was in favor of placebo. A pooled analysis of all data on walking distance showed that ketanserin significantly increased walking distance by 65%, whereas placebo significantly increased it by 25%. However, the intergroup comparison does not show significant differences. Comparison of individual responses, on the other hand, showed that more patients experienced a doubling of walking distance on ketanserin than on placebo (25 versus 13%), and fewer patients deteriorated on ketanserin than on placebo (23 versus 32%); this difference in response rate is significant (p less than 0.05). In these studies there was a striking difference in drop-out rate between ketanserin and placebo. In total, 25 patients dropped out during placebo treatment versus 14 during ketanserin treatment. Nine of the 25 dropouts on placebo suffered severe "cardiovascular events," whereas no such events were observed in the ketanserin group. This difference is highly significant and suggests that ketanserin may have a vascular protective effect in patients with intermittent claudication. This possibility is being investigated in a prospective trial (PACK trial).

Blood Pressure↗