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Biomedical subjects

P Valensi

Publications and source records attributed to P Valensi.

At least 109 records · Page 6Linked to original sources
PubMed1994

Thyroid stimulating antibodies in sarcoidosis.

OBJECTIVES: Thyroid disorders, particularly euthyroid goiters and hyperthyroidism, can be observed in sarcoidosis. The aim of this study was to analyze the presence of thyroid stimulating antibodies (TSAb) in 21 patients with sarcoidosis. 12 patients out of 21 had simultaneous euthyroid goiter. The others were euthyroid and free of goiter. METHODS: The TSAb testing was carried out using the rat thyroid fragment perifusion technique. Thyroid response to IgG was determined by the mean rate of T4 release (R) during a 30-min perifusion and the secretion peak (Imax). Antibodies inhibiting TSH binding to its receptors were also looked for. RESULTS: Ten patients were TSAb+ and eleven were TSAb-. There was no difference between the TSAb+ and TSAb- groups in the clinical parameters for sarcoidosis, nor in the number of goiters found (n = 6 for both groups). In 5 out of the 6 cases where goiter was present in the TSAb+ group it was homogeneous and diagnosed at the same time as or after the first signs of sarcoidosis, whereas in 5 out of the 6 cases of goiter in TSAb- patients, it was nodular, diagnosed before sarcoidosis in 3 of them, endemic in one of them, and familial in another. The search for antibodies inhibiting TSH binding to its receptors was negative in 10 out of 21 patients tested. CONCLUSION: Although the presence of thyroid-stimulating antibodies in the serum of patients with sarcoidosis, found here for the first time, remains to be explained, it pleads in favor of the immunologic nature of the association of sarcoidosis with thyroid disorders.

Adult↗
PubMed1993

[Hemodynamics of massive obesity].

Congestive heart failure is a frequent complication of massive obesity and a major cause of death. Prior to the cardiac decompensation stage, infraclinical haemodynamic disturbances can be observed in obese subjects with normal blood pressure: the cardiac output and cardiac index increase, due to a rise in systolic ejection volume, the total peripheral resistance falls and the intravascular volume augments. Cardiac adjustment takes place in the form of excentric left ventricular hypertrophy. Ventricular extrasystoles, often associated with this hypertrophy, might be the cause of sudden death in some obese patients. Arterial hypertension is about 3 times more frequent in obese subjects than in subjects of normal weight, and even more frequent in those with massive obesity. To the high preload due to obesity hypertension adds an increased after-load. This results in augmentation of the mass and work of the left ventricle with progressive alteration of its function. The incidence of coronary disease is increased in obese subjects, notably those with abnormal adiposity. Finally, the return circulation is very often perturbed, notably in gynecoid obesity: there is venous insufficiency with a higher risk for thromboembolism, and lymphatic insufficiency or capillary permeability disorders. A low-calorie diet and a physical rehabilitation of sedentary obese subjects facilitate weight reduction and at the same time tend to correct the associated metabolic disturbances; they reduce blood pressure and also seem to reduce the left ventricular hypertrophy.

Cardiovascular Diseases↗
PubMed1993

[Autonomic diabetic neuropathy].

Diabetic autonomic neuropathy is rarely symptomatic but very frequent at a subclinical stage. Symptoms may be gastrointestinal, urinary, genital or cardiac. Sudoral, vasomotor or pupillary symptoms may also occur. Standardized cardiovascular tests are used to investigate parasympathetic and sympathetic nervous control. Because of their easy feasibility and good reproducibility they might be performed in the largest part of the diabetic population. These tests also strongly suggest that cardiac autonomic neuropathy is of poor prognosis, even when it is subclinical. Most treatments are symptomatic, but optimized diabetes control and administration of aldose reductase inhibitors are rational therapeutic measures, although their long-term effectiveness remains to be demonstrated.

Diabetic Neuropathies↗
PubMed1993

Glucagon and noradrenaline reduce erythrocyte deformability.

An impairment in red blood cell (RBC) deformability has been reported in several diseases and might be involved in the pathogenesis of atherosclerosis. The aim of the present study was to test in vitro the effect of two "stress hormones," norepinephrine and glucagon, on the filterability of RBCs from healthy subjects. Measurements were performed with the Hanss hemorrheometer, and results were expressed as the rigidity index (RI). All concentrations of norepinephrine from 10(-7) to 10(-4) mol/L induced a significant increase in RI compared with Hanks buffer, with the maximal effect being reached using 10(-6) mol/L. All concentrations of glucagon from 0.01 to 5 ng/mL also induced a significant increase in RI, with the maximal effect being achieved using 1 ng/mL. These data suggest that these two stress hormones could be involved in the rheologic impairments found in several diseases and therefore in the pathogenesis of atherosclerosis.

Adolescent↗
PubMed1993

Reproducibility of parameters for assessment of diabetic neuropathy. The French Group for Research and Study of Diabetic Neuropathy.

This study evaluated the reproducibility of nerve function assessment in a group of 132 diabetic patients with moderate peripheral polyneuropathy. Patients were investigated at the beginning and the end of the run-in period (a 1-month placebo period) of a multicentre trial of an aldose-reductase inhibitor (Ponalrestat). Reproducibility was evaluated by performing four types of tests: quantitative visual scales of symptoms, quantitative sensory assessment (vibration perception thresholds in medial malleolus and great toe, foot thermal perception threshold to hot and cold), electrophysiological investigations on the dominant side (conduction velocities and potential amplitudes of sensory and median motor nerve, sural and peroneal nerves, amplitudes of F waves of median motor and peroneal nerves) and cardiac autonomic tests (Valsalva, deep-breathing, lying-to-standing). Reproducibility was poor for symptoms, thermal sensitivity, and potential amplitudes. It was satisfactory (total coefficient of variation < 50%) for all the other parameters and even very good (total variation coefficient < 26%, intra-subject variation factors corresponding to < 56% of total variance) for velocities of sensory and median motor and peroneal nerves, the amplitudes of F waves and the three autonomic tests. For most of the parameters total variance was mainly related to inter-subject variability. However, inter-subject variability for the three cardiac autonomic tests was very low and at least one cardiac autonomic test was altered in all the patients. Inter-centre variability was low for all the parameters, except for action potential amplitudes and for F wave velocity of the median motor nerve. This study suggests those parameters that are appropriate for the assessment of diabetic neuropathy and for therapeutic trials.(ABSTRACT TRUNCATED AT 250 WORDS)

Aldehyde Reductase↗
PubMed1993

Impairment of coronary vascular reserve and ACh-induced coronary vasodilation in diabetic patients with angiographically normal coronary arteries and normal left ventricular systolic function.

Evidence is increasing for small-vessel disease and disturbance of endothelium-dependent vasodilation in diabetic patients. The aim of this study was to compare coronary circulation in 11 diabetic patients (6 type I and 5 type II) and 7 control subjects. All patients had normal left ventricular systolic function and angiographically normal coronary arteries. To evaluate the maximal area of coronary microcirculation, coronary vascular reserve was determined by intracoronary Doppler and a maximally vasodilating dose of intracoronary papaverine (peak-to-resting coronary flow velocity ratio). To assess coronary endothelial function responses to stepwise intracoronary infusion of acetylcholine (10(-8) to 10(-5) M coronary estimated concentrations) were analyzed on four different segments in each patient by quantitative angiography. Peak-to-resting coronary flow velocity ratio was lower in diabetic patients than in control subjects (3.9 +/- 0.9 and 5.0 +/- 0.7, respectively, P < 0.02). Acetylcholine did not produce any diameter change at 10(-8) and 10(-7) M, but a progressive diameter reduction was observed at 10(-6) and 10(-5) M (-8.0 +/- 15.2%, P < 0.02 and -24.0 +/- 13.6%, P < 0.001, respectively). In control subjects, a progressive diameter dilation was produced from 10(-8) to 10(-6) M acetylcholine (5.1 +/- 3.4, 12.1 +/- 7.0, and 16.4 +/- 7.3%, respectively, all P < 0.001), and a moderate reduction was observed at 10(-5) M (-4.9 +/- 7.5%, P < 0.02). In the two groups, all segments dilated similarly after intracoronary isosorbide dinitrate.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗
PubMed1992

[Pathogenic role of hyperinsulinism in macroangiopathy. Epidemiological data].

The hypothesis of the atherogenic role of endogenous insulin was based on a series of epidemiological studies. Several large-scale prospective studies have demonstrated that diabetes constitutes an independent risk factor for cardiovascular disease. However, neither the duration of diabetes nor the blood glucose level appear to be predictive of the incidence of a cardiovascular accident. More recent prospective studies (Finland, Australia, Paris) in non-diabetic men have shown that hyperinsulinemia, while fasting or after glucose stimulation, constitutes a risk factor for fatal myocardial infarction, but they failed to show whether diabetes or the blood glucose level constituted a risk factor for the disease. Cross-sectional studies have provided similar results. Insulin resistance affects the majority of non-insulin-dependent diabetics and glucose-intolerant patients. It has also been observed in 25 percent of non-obese subjects with a normal glucose tolerance test. Associated hyperinsulinemia prevents the development of diabetes, but diabetes appears when the beta-cell function is altered and can no longer maintain this hyperinsulinemia. However, hyperinsulinemia is not devoid of cardiovascular consequences. Insulin resistance and hyperinsulinemia are also observed in patients with essential hypertension: a correlation between plasma insulin and blood pressure has been reported. These data, together with other experimental arguments, suggest that excessive endogenous insulin may participate in the rise in blood pressure. Furthermore, hypertensive patients have a high risk of coronary heart disease and this risk is not significantly decreased by anti-hypertensive treatments. This is probably related to the presence of other metabolic risk factors associated with insulin resistance: hyperinsulinemia, glucose intolerance, hypertriglyceridemia, decreased HDL cholesterol. These metabolic disorders have been grouped together under the term "syndrome X". All of these risk factors are probably also involved in the development of coronary heart disease in general population. In conclusion, epidemiological studies now suggest that insulin resistance and hyperinsulinemia increase the risk of hypertension and coronary heart disease. A great many experimental studies support this hypothesis. Lastly, it can be proposed that the increased cardiovascular risk in non-insulin-dependent diabetics is related to the fact that they belong to a larger group of insulin-resistant subjects. The management of diabetes, hypertension, and all of the metabolic abnormalities would appear to be the only way of reducing the incidence of cardiovascular disease.

Coronary Disease↗
PubMed1992

[Diabetic neuropathy. Difficulties of diagnosis and choice of tests].

None of the classifications of diabetic neuropathy already published is perfect. "Experts" now recommend an operational classification based on the quantification of signs and neurological deficits, on an electrophysiological investigation and on an easy exploration of autonomic neuropathy. Quantitative evaluation of symptoms can be performed with questionnaires or scales. Quantitative evaluation of deficits can be performed with devices which quantify vibratory and thermic sensations; reproducibility of the results is not yet perfect, but it represents a clear progress over clinical examination. Investigation of the autonomic control of cardiovascular system with standardized tests is the simplest way of exploring the vegetative nervous system; these tests have a fair sensitivity and an excellent reproducibility. Therapeutic trials, particularly with aldose reductase inhibitors or gangliosides, require this wide panel of neurological investigations.

Diabetic Neuropathies↗
PubMed1992

Comparative effects of diabetes mellitus and hypertension on physical properties of human large arteries.

OBJECTIVES: The effects of hypertension and diabetes on the physical properties of large arteries were compared in men. BACKGROUND: Although these two diseases are linked to vascular stiffening, no study has analyzed whether the arterial rigidity in diabetes is as substantial as in hypertension. METHODS: Noninvasive measurements of brachial artery mean pressure, diameter (pulsed Doppler study) and compliance (pulse wave velocity) were obtained in 29 men: 11 control subjects, 9 hypertensive nondiabetic patients and 9 diabetic normotensive patients. Individual diameter- and compliance-pressure curves extrapolated from the measured diameter and mean pressure point with a logarithmic elastic model permitted calculation of isobaric diameter and compliance at the same pressure in each subject. RESULTS: Compared with control subjects, hypertensive patients had a larger brachial artery measured diameter and isobaric diameter (p < 0.01) and lower measured and isobaric compliance (p < 0.001, p < 0.01). Compared with control subjects, diabetic patients had lower measured and isobaric compliance (p < 0.01). Comparison of diabetic and hypertensive patients showed that measured diameter and isobaric diameter were decreased in the former (p < 0.01). In the control and hypertensive groups, mean pressure correlated positively with measured diameter and isobaric diameter (p < 0.01) and negatively with measured and isobaric compliance (p < 0.001 and p < 0.01, respectively). In the control and diabetic groups, fasting glucose correlated negatively with measured and isobaric compliance (p < 0.01, p < 0.05). CONCLUSIONS: Intrinsic alterations of the large artery independent of a stretching pressure effect reduce arterial elasticity similarly in those with hypertension or diabetes. The loss of compliance is related to the chronic elevation of blood pressure in hypertension and to that of glycemia in diabetes and is associated with a relative large artery vasoconstriction in diabetic patients as compared with patients with hypertension.

Adult↗
PubMed1992

Non-beta-adrenergic-mediated peripheral circulatory hyperkinesia in hyperthyroidism.

Systolic time intervals and brachial circulation, evaluated by pulsed Doppler in terms of arterial diameter, blood velocity and flow, and vascular resistance, were studied in 12 hyperthyroid patients and in 12 normal controls. In patients, arterial circulation was studied before and during mechanical exclusion of the hand, and hemodynamic measurements were repeated after beta-blocker treatment and after obtainment of euthyroid state. Compared with controls, patients had higher heart rate (P < 0.001), lower systolic time intervals (P < 0.05, P < 0.01), and higher blood velocity (P < 0.05). Beta blockade decreased heart rate (P < 0.05, P < 0.001) but did not change systolic time intervals and arterial circulation. Euthyroid state decreased heart rate (P < 0.01), preejection period (P < 0.01), and blood velocity (P < 0.01) and flow (P < 0.05). The decreases in velocity and flow before hand exclusion when euthyroid state was obtained were correlated with hyperthyroid values of velocity and flow respectively (r = 0.85, r = 0.90, P < 0.01, P < 0.001). Vascular resistance during hand exclusion was correlated negatively with serum T3 level during hyperthyroid and euthyroid states. Thus, thyroid hormones but not beta-adrenoreceptors participate in the peripheral hyperkinesia of hyperthyroidism.

Adrenergic beta-Antagonists↗
PubMed1992

[Microalbuminuria and hypertension in obese patients].

The present study was designed to evaluate the frequency of an increase in the urinary albumin excretion rate (UAER) and the factors involved in this parameter in non-diabetic obese patients; 122 non-diabetic obese patients were investigated. None had proteinuria or history of nephropathy or uropathy. Fourty of them had moderate hypertension. Compared with a group of 22 lean controls, UAER was significantly higher in the obese patients (19.0 +/- 2.0 (SEM) mg/24 h vs 3.2 +/- 0.6 mg/24 h, p < 0.001). UAER was elevated (> 20 mg/24 h) in 29 patients (23.7%). Prevalence of microalbuminuria was not significantly different in hypertensive than in normotensive patients. However UAER was significantly higher in the 32 patients with a family history of hypertension (29.6 +/- 6.3 mg/24 h vs 15.3 +/- 1.5 mg/24 h, p < 0.002). In patients with microalbuminuria, body weight was significantly higher (100.3 +/- 3.9 kg vs 91.8 +/- 1.9 kg, p < 0.05), plasma albumin was significantly lower (38.3 +/- 0.6 g/l vs 40.3 +/- 0.3 g/l, p < 0.005) and the estimated value of fractional albumin clearance was significantly higher. These results show the high frequency of microalbuminuria in non-diabetic obese patients. They suggest that UAER level may be an index of family hypertension in obese patients and that microalbuminuria is part of a widespread abnormality of the capillary permeability.

Adult↗
PubMed1991

Increased capillary permeability to albumin and diabetic neuropathy.

An increase in the capillary permeability to albumin (CPA) has been reported in diabetic patients. We observed this frequently with a non-invasive isotopic test derived from the Landis method, using 99mTc-albumin and measuring residual radioactivity externally after removal of forearm venous compression. Evidence of the independent effects of hypertension and microangiopathy on CPA has already been found. The present work was designed to investigate CPA using the same test on diabetic patients without retinopathy and clinical proteinuria. Some of these patients had objective clinical distal and symmetrical polyneuropathy. Neuropathy was clearly present in 10 of the 11 patients with an abnormal test unexplained by causes other than diabetes and in only one of the 17 patients with a normal test. The most frequent abnormality affected the late radioactivity disappearance curve, which probably reflects an impaired lymphatic wash-out of interstitial albumin. These results strongly suggest a link between peripheral neuropathy and diabetic functional microangiopathy. An elevated blood flow secondary to sympathetic nerve failure may induce an increase in CPA and a saturation of lymphatic pumping which could also be deficient due to impaired lymphatic innervation.

Adult↗
PubMed1991

Effects of nifedipine and nitrendipine on insulin secretion in obese patients.

Data on the influence of calcium antagonists on glucose tolerance and insulin release in humans are conflicting. The present double-blind, double-dummy, controlled trial was designed to investigate the effect of a short-term (7 days) treatment with nitrendipine, 20 mg b.i.d.; nitrendipine, 20 mg once daily; or placebo on blood glucose and plasma insulin and C-peptide response to an intravenous glucose load in mildly or transiently hypertensive nondiabetic obese patients. No statistically significant differences were found in fasting glucose, insulin, and C-peptide, or in the glucose disappearance rate and in any of the parameters for insulin and C-peptide response after i.v. glucose, between the three groups of patients. However, a slight decrease in early insulin response to glucose was observed in the nifedipine and the nitrendipine groups. This study confirms that calcium antagonists have no clinically relevant effect on glucose homeostasis even if a slight alteration of insulin release after glucose load cannot be ruled out.

Adult↗
PubMed1991

[Comparison of isobaric effects of hypertension and diabetes mellitus on geometric and elastic properties of human arteries].

Hypertensive and diabetic mellitus diseases are known to increase stiffness of the arterial wall. However these alterations probably involve different mechanisms. To this end, we compared the effect of hypertension and diabetes on large artery caliber and elasticity at real pressure conditions and at the same level of pressure. Nine poorly controlled non insulino-dependent diabetic men without hypertension and 9 non-diabetic essential hypertensive men underwent measures of lumen diameter (pulsed Doppler) and segmental compliance (Bramwell and Hill formula; pulse wave velocity) at the brachial artery. Isobaric diameter and compliance were deduced from a non linear model, comparing diameter and pressure on one part, and compliance and pressure on the other. Pulse wave velocity was similarly increased in both diseases (11.5 +/- 1 vs 12.8 +/- 1 m/s; NS; respectively in diabetes and hypertension). Both measured and isobaric diameters were smaller in diabetic patients (4.05 +/- 0.2 vs 5.03 +/- 0.2 mm, p less than 0.1% for the measured diameters respectively in diabetes and hypertension and 4.06 +/- 0.2 vs 5.01 +/- 0.2 mm, p less than 1% for isobaric diameters). The measured and isobaric compliances were not significantly different (2.38 +/- 0.4 vs 2.08 +/- 0.2 cm/mmHg10(-4), NS, for the measured compliance respectively in diabetes and hypertension; 2.28 +/- 0.4 vs 2.4 +/- 0.2, NS for the isobaric compliance). After correction of the effect of mechanical arterial stretch induced by the different blood pressure level of the two groups, significant reduction of diameter in diabetic subjects persisted and isobaric and measured compliances remained unchanged between groups.

Adult↗
PubMed1991

Effect of nifedipine and nitrendipine on insulin release in non-diabetic obese patients: a double-blind, placebo-controlled study.

Calcium antagonists are known to decrease insulin release in vitro. In vivo, their effects on insulin secretion and glucose tolerance are more controversial. We carried out a double-blind, double-dummy, controlled trial to study the effects of nifedipine (40 mg/day; n = 9), nitrendipine (20 mg/day; n = 9) and placebo (n = 10) on insulin release in 3 parallel groups of obese patients with mild or transient hypertension and a normal oral glucose tolerance test. The treatment lasted one week. Patients were asked not to modify their diet throughout the trial, and their body weight did not vary significantly. A 2-hour i.v. glucose tolerance test was performed twice in every patient, just before the first drug intake and one hour after the last one. The following parameters were measured or calculated during each test: basal, peak and early phase levels of blood glucose, insulin and C-peptide; glucose disappearance rate; and glucose, insulin and C-peptide incremental areas under the time-curves. On day 1, the 3 groups of patients were comparable for age, sex, body weight and every biological parameter. One-way analysis of variance did not show any significantly different evolution of those parameters between the 3 treatment groups, but calcium antagonists tended to slightly reduce the early phase of insulin release compared with placebo.

Adolescent↗