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Biomedical subjects

M Chaignon

Publications and source records attributed to M Chaignon.

At least 19 recordsLinked to original sources
PubMed2000

[Microabluminuria in arterial hypertension. Measurement, variables, interpretation, recommendations].

Permanent hypertension is frequently associated with increased glomerular permeability to albumin at an early stage, indicating renal involvement and endothelial dysfunction. The definition of microalbuminuria is an urinary albumin excretion of 30-300 mg/24 hrs, confirmed on two occasions over a 3 month period. It may also be expressed in microgram/min, m/l or mg/mmol of creatinine. Radio-immunological, immunonephelometric methods and Elisa are specific and the most sensitive methods of measurement. There is a large intra-individual variability (25-60%) making it essential to repeat measurements always by the same technique. The prevalence of microalbuminuria is 5-8% in the general population and 6-24% in hypertensive patients. When present, it is a marker of increased cardiovascular risk. Clinical recommendations suggest adaptation of urinary collection according to the context: screening, diagnosis or clinical research. It is always necessary to start by dip-stick detection of proteinuria, haematuria or urinary infection. Clinical research requires repeated measurement of 24 hour microalbuminuria, sometimes divided into two periods of day and night, often associated with ambulatory blood pressure recordings and renal function tests. Studies of the effects of anti-hypertensive drugs on microalbuminuria could provide better evaluation. In conclusion, measurement of microalbuminuria remains a tool of clinical research allowing an assessment of cardiovascular and renal risk of hypertensive patients.

Albuminuria↗
PubMed1996

Repeated measurements of non-invasive ambulatory blood pressure: distinction between reproducibility and the proper effect of placebo.

OBJECTIVE: To determine whether non-invasive ambulatory blood pressure is more reproducible and less affected by the placebo treatment than are clinic blood pressure measurements. METHOD: Thirty-four essential hypertensive outpatients were randomly allocated after a 4-week preselection period in two groups in a cross-over study design. One group received placebo for 4 weeks while the other formed the control group (reproducibility), then the treatments were exchanged for another 4 weeks. Clinic and ambulatory blood pressures were measured at three different times for each patient, namely bnefore the random allocation to groups and at the end of each period, using a mercury sphygmomanometer and 24 h non-invasive ambulatory blood pressure monitoring. RESULTS: Administration of placebo was accompanied by a significant reduction in systolic and diastolic clinic blood pressures (by 3.4+/-13 and 3.6+/-8 mmHg, respectively), but not in 24 h, daytime and night-time blood pressures. Circadian hourly blood pressure and heart rate curves were virtually superimposable. In the 13 placebo responder patients selected on the basis of clinic blood pressure, placebo decreased the clinic blood pressure and also reduced systolic and diastolic ambulatory blood pressures, mainly during the day period (by 5.2+/-6.2 and 4.89+/-7.8 mmHg, respectively). This effect is specific and related to the placebo administration because repetition of the measurements without any treatment showed no significant difference. To characterize at baseline the placebo responder patients, comparison with the non-placebo responders showed lower baseline values of ambulatory systolic blood pressure recorded during 24 h daytime and night-time in the placebo responder group. CONCLUSION: The 24 h ambulatory blood pressure average is not affected by placebo in the present group of patients but that a placebo effect occurs mainly during the daytime in patients who decreased their clinic blood pressure under placebo (placebo responders); the placebo-induced reduction in blood pressure is related to a specific effect of placebo and is independent from any alerting reaction or reproducibility hypothesis. This study clearly indicates the necessity of including placebo and ambulatory blood pressure monitoring in the therapeutic and pharmacological trials of antihypertensive drugs.

Journal Article↗
PubMed1992

[Arterial hypertension and diabetic nephropathy].

A high incidence of renal lesions is observed in patients with insulin-dependent diabetes. In the early stages of the disease glomerular capillary hemodynamics is altered with, in particular, glomerular hyperfiltration related to several factors: enhanced glomerular capillary flow rate, capillary hypertension and increased filtration area. These hemodynamic changes could affect development of the glomerular microangiopathy: the final outcome of this is the glomerulosclerosis associated with a progressively worsening and ineluctable chronic renal insufficiency. Hypertension, frequent in the early stages, is practically constant when the neuropathy stage has been reached; it is well established that hypertension accelerates the development of glomerular lesions and the progression of the renal impairment. Experimental and clinical studies have clearly demonstrated that antihypertensive treatment slows down the degradation of renal function. All antihypertensive drugs appear to be effective, but converting enzyme inhibitors, by their effects on renal hemodynamics, could play a particular role in the prophylactic treatment of diabetic nephropathy. Determination of urinary excretion of albumin (microalbuminuria), the global evidence of the onset of a nephropathy is useful for the follow up of the renal disease, allows follow up of the renal lesion and evaluation of the efficacy of treatment.

Diabetic Nephropathies↗
PubMed1990

Effects of sustained-release diltiazem on blood pressure and serum lipids: a multicenter, randomized, placebo-controlled study.

A randomized, double-blind dose-response study on the antihypertensive action of sustained-release diltiazem was performed in four parallel groups. The aim of the trial was to evaluate the antihypertensive efficacy of sustained-release diltiazem and its dose-dependent clinical and biological tolerance. The four homogeneous groups consisted of 25 patients each who had presented with mild to moderate hypertension (diastolic blood pressure of 95-115 mm Hg) in the supine position. The study protocol comprised three successive periods: a placebo period lasting 14 days to verify the persistence of arterial hypertension under placebo; a first therapeutic period during which each of the 25 patients of the four groups received a single daily dose every morning at 9 a.m. of a capsule containing 0.240, 300, or 360 mg of sustained-release diltiazem over a period of 28 days; and a second therapeutic period during which the patients of the four groups received 240, 300, 360, and 300 mg, respectively. All other antihypertensive treatment had been suspended at least 15 days before the initial period under placebo. The results were evaluated with respect to clinical parameters such as systolic blood pressure, diastolic blood pressure, and heart rate, which were measured at 9 a.m. 24 h after the last administration of the drug on days 14, 28, and 56. The plasma serum levels of diltiazem were measured on days 28 and 56, the biological parameters, including measurements of hepatic and renal function as well as lipid and glucose levels, on days 14 and 56, and electrocardiography was performed on days 14, 28, and 56.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Pressure↗
PubMed1990

[Renal effects of intravenous tertatolol in essential arterial hypertension].

The acute renal effects of intravenous tertatolol were studied in eight patients with moderate essential hypertension: the study included a 100 mmol/day sodium intake during 3 days. Then, tertatolol was infused after a water load during 2 consecutive periods of 30 min (priming dose followed by constant infusion) in order to obtain plasma concentrations of tertatolol at 2 different levels: 10 ng/ml, then 40 ng/ml successively; the measurements were obtained at 15, 30, 45 and 60 min. The renal plasma flow (RPF) and the glomerular filtration rate (GFR) were calculated from the 131I-Hippuran clearance and the 125I-Iothalamate clearance respectively; a bladder catheter allowed a precise urine collection. The results indicate that intravenous tertatolol, at low dose, induced a marked and early renal vasodilatation; higher dose of tertatolol attenuated the vasodilator response, probably because of a decrease in cardiac output (suggested by the decrease in heart rate); thus, the systemic effects would hide the direct renal hemodynamic effects of tertatolol. Natriuresis and kaliuresis were unchanged by intravenous tertatolol.

Adrenergic beta-Antagonists↗
PubMed1989

[Arterial pressure--self measurement. Recommendations. French Society for Arterial Hypertension--the Measurement Group].

Self-measurement of blood pressure has become widespread in recent years. It may be defined as the measurement of arterial pressure by a conscious and free-willed subject. Self-measurement must remain a medical procedure, which means that doctors should be able to advise their patients (a) on the type of apparatus they should purchase and get validated at regular intervals; (b) on the method of using the apparatus in practice, and (c) on the circumstances, conditions and numbers of measurements to be performed. Doctors must remain responsible for the interpretation of the results obtained and for the diagnostic, pronostic an therapeutic applications of the method. Self-measurement of blood pressure naturally has advantages and disadvantages, but it must be noted that it may offer an alternative to hospitalization or to ambulatory arterial pressure measurement, avoid excessive or defective therapies and improve the patient's compliance with his treatment.

Blood Pressure Determination↗
PubMed1989

[Renal effects of captopril in hypertension with renal artery stenosis. Comparison between Tc-99m-DTPA scintigraphy and clearance method].

In eleven hypertensive patients with renal artery stenosis, the acute renal effects of captopril were investigated using two methods: 1) the Tc99m-DTPA renography with determination of an index of renal perfusion (IP), an index of glomerular filtration (IF) and the ratio of these indices (F/P); 2) the renal hemodynamics obtained by the clearance method using a continuous infusion of I131-hippuran and I125-iothalamate for calculation of renal blood flow (RBF), glomerular filtration rate (GFR) and filtration fraction (FF). The studies were performed before and after captopril treatment. Patients were classified according to the acute response to captopril as responders (R; n = 6) and non responders (NR; n = 5). Results are as follows: (B: basal, C = captopril). (table; see text) These data confirm that captopril produced a significant decrease in F/P and FF in R whereas these indices did not change in NR; it was found that IF and GFR decreased in R whereas IF increased and GFR did not change in NR; a significant correlation was observed between delta IF and delta GFR in R (r = 0.834, p less than 0.05). These results indicate that 1) data obtained before and after captopril by renography and by clearance methods are in good correlation either in Ror in NR patients; 2) Captopril test including renography or renal hemodynamic measurements is useful for selection of R patients.

Adult↗
PubMed1988

[Effects of converting enzyme inhibition by enalapril on renal hemodynamics in essential arterial hypertension].

The effects of enalapril, an angiotensin-converting enzyme inhibitor, on renal haemodynamics were studied in 10 patients with moderates essential hypertension and no renal failure. Renal blood flow and glomerular filtration were measured (by I 131-hippuran and I 125-iothalamate clearances respectively), before ("placebo period"), and after 15 days of treatment with enalapril 40 mg/day. The drug clearly had an antihypertensive effect: systolic pressure fell from 169 +/- 4 to 149 +/- 5 mmHg (P less than 0.01), and diastolic pressure from 111 +/- 3 to 94 +/- 3 mmHg (P less than 0.01). Enalapril induced marked renal vasodilatation: renal vascular resistance decreased from 0.18 +/- 0.01 to 0.14 +/- 0.01 A.U. (P less than 0.01); renal blood flow was moderately increased (from 764 +/- 43 to 829 +/- 43 ml/min/1.73 m2, P less than 0.05), while glomerular filtration rate remained unmodified (118 +/- 4 versus 120 +/- 6 ml/min/1.73 m2, NS). Under enalapril, the filtration fraction decreased from 0.29 +/- 0.01 to 0.26 +/- 0.01 (P less than 0.01). These results confirmed that enalapril produces dilatation of both the afferent and efferent arterioles - a mechanism that might lower perfusion pressure in the glomerular capillary vessels.

Adult↗
PubMed1988

[The effects of inhibition of converting enzyme by perindopril on renal hemodynamics and natriuresis in essential arterial hypertension].

Renal hemodynamics and natriuresis have been studied before and 6 hours after oral intake of perindopril (8 mg) in 8 hypertensive patients without renal failure. Then, the patients were treated with perindopril (8 mg per day) and renal hemodynamics was repeated on the fifth day, 6 hours after the morning intake of the substance. Sodium diet was controlled during the study (100 mmol sodium per day). Renal blood flow (RBF) and glomerular filtration rate (GFR) were measured by the clearance method using 131I-hippuran and 125I-iothalamate respectively. The results are as follows: (table; see text) Perindopril produced a potent renal vasodilatation after the first intake and the following days without any change in GFR. A significant decrease in FF was observed indicating that efferent as well as afferent arteriolar vasodilatation was induced. Perindopril produced an increase in natriuresis after the first intake and at D5; this natriuretic effect may be related to the changes in renal hemodynamics inducing a decreased sodium reabsorption in the proximal tubule.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1988

Effects of perindopril on renal haemodynamics and natriuresis in essential hypertension.

Renal haemodynamics and natriuresis were studied before and 6 h after oral intake of perindopril (8 mg) in eight hypertensive patients without renal failure. The patients were then treated with perindopril (8 mg per day) and renal haemodynamics were measured on the fifth day, 6 h after the morning intake. Sodium intake was controlled during the study (100 mmol sodium per day). Renal blood flow and the glomerular filtration rate were measured by the clearance method using 131I-hippuran and 125I-iothalamate, respectively. Mean blood pressure decreased from 135 to 110 after 6 h, and was 118 mmHg on the fifth day (P less than 0.001, respectively). Renal vascular resistance decreased significantly after acute drug intake from 0.19 to 0.15 arbitrary units (P less than 0.001) and on the fifth day to 0.16 arbitrary units (P less than 0.001). Renal blood flow rose from 708 to 723 after 6 h, and to 750 ml/min per 1.73 m2 on the fifth day but the change was no significant. There was no alteration in the glomerular filtration rate so that the filtration fraction decreased from 0.27 to 0.26 (after 6 h), and to 0.25 on the fifth day (P less than 0.02). Natriuresis increased after the first intake between the first and tenth hours. On the fifth day, maximum natriuresis was observed between the fourth and sixth hours. Perindopril caused strong renal vasodilation after the first intake and during the following days, with no change in the glomerular filtration rate. There was a significant decrease in the filtration fraction, indicating efferent, as well as afferent, arteriolar vasodilation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

[Acute hemodynamic study of intravenous nicardipine in arterial hypertension].

The acute hemodynamic effects of intravenous Nicardipine (N), a new calcium antagonist, were studied in 8 patients with moderate essential hypertension. The forearm arterial blood flow (ABF) was measured using plethysmography before and after N infusion: 1st step was obtained after infusion of 1 mg during 5 min then 1 mg during 25 min; a second step was obtained after the infusion of the same dose during the same time; thus a cumulative dosage of 4 mg was infused over a total duration of 60 mn. Systolic (SBP), diastolic (DBP) mean (MBP) blood pressure and heart rate (HR) were measured every minute using a non invasive device (Dinamap). Systemic vascular resistances (SVR) were calculated. Plasma concentration of N was determined at the beginning, in the middle and at the end of each step. Results are as follows: (table; see text) A 33% decrease in SVR was observed at the 2nd step whereas MBP decreased by 15% only. The date confirm the potent vasodilatory effect of intravenous N at low dosage; the BP alteration was moderate in relation to an increase in local blood flow. These results indicate that Nicardipine could be useful as part of the treatment of chronic arteriopathy and Raynaud disease.

Blood Pressure↗