[Paradoxal decrease and metabolic effects of BNP in obese patient]. / Baisse paradoxale et effet métabolique du BNP chez les obèses.

Natriuretic peptides (NP), ANP and BNP, are produced by cardiomyocytes when there is stretching of the ventricular and auricular walls in heart failure (HF). Their vasodilatator and natriuretic effect oppose to volume and pressure overload occurring in HF. Several studies have observed decreased levels of NP in obese and diabetic people and in patients with insulin resistance. This decrease could contribute to hypertension, frequently observed in obesity. NP have also a lipolytic action. Low levels of NP could promote obesity. Therefore in obese patients normal BNP levels cannot a priori exclude HF. Normal values must be adjusted according to obesity degree and heart failure stage.

Les peptides natriurétiques (PN) ANP (atrial natriuretic peptide) et BNP (brain natriuretic peptide) sont synthétisés par les cardiomyocytes lors de mise sous tension des parois musculaires des ventricules et des oreillettes en cas d'insuffisance cardiaque (IC). Leur effet vasodilatateur et natriurétique s'oppose à la surcharge de volume et de pression qui survient lors d'IC. Plusieurs études ont montré que les taux de BNP sont diminués chez les patients obèses, diabétiques ou présentant une résistance à l'insuline. La baisse de BNP pourrait contribuer à l'hypertension observée chez les obèses. De plus les PN ont une action lipolytique. Des taux abaissés de PN pourraient favoriser l'obésité. En pratique, chez les obèses, des valeurs normales de BNP ne permettent pas d'exclure une IC. Les valeurs de BNP doivent être corrigées en fonction des degrés d'obésité et d'IC.

[Metabolic syndrome: jumble syndrome of obesity or specific entity? Which treatment: diet or polypill?]. / Syndrome métabolique: syndrome fourre-tout des patients obèses ou entité spécifique? Quel traitement: hygiene de vie ou potypill?

The reality of metabolic syndrome (MS) as a specific entity is debatable. However, the simple measure of waist circumference (>94 cm in men and >80 cm in women) is useful: (1) to check for insulin resistance by measuring serum levels of fasted glucose and insuline, cholesterol, triglycerides; (2) to look for diseases associated with MS such as hypertension, non alcohoolic steatohepatitis, sleep apnea, polycystic ovary disease, hypogonadism and to measure serum levels of ferritine, ALAT, ASAT, urate acid, CRP hs, testosterone and (3) to make obese people aware of their risk of becoming diabetic and to motivate them to change their life style. The utility of exercise and of various diets is discussed as well as the efficiency of drugs acting on different components of MS such as rimonabant, orlistat, metformin, glitazones, telmisartan and testosterone. The importance of political measures to fight the obesity epidemic is underlined.

The role of body position and gravity in the symptoms and treatment of various medical diseases.

Postural medicine studies the effects of gravity on human body functions and the ability to influence various diseases by changing the body's position. Orthostasis requires numerous cardiovascular and neurohumoral adaptations to prevent hypotension and a resulting decrease in cerebral perfusion. Sitting upright or in a semi-sitting position reduces venous return in patients with heart failure, intracranial pressure in patients with intracranial hypertension, intraocular pressure in glaucoma patients and may decrease gastro-oesophageal reflux. A left recumbent posture also decreases reflux. A right lateral position results in a lower sympathetic tone than lying on the left side and is beneficial in patients with heart failure or after an infarction without bradycardia. A 40 to 70% decreased prevalence of the sudden infant death syndrome has been observed since the recommendation to avoid laying infants to sleep in a prone position. Sleeping in a supine posture increases the severity of sleep apnoea compared to a lateral position. In patients with acute respiratory distress syndrome, a prone position can rapidly improve blood oxygenation. Idiopathic oedema, orthostatic proteinuria, intradiscal pressure and venous circulation in legs are improved in the decubitus position, whereas arterial flow is reduced. Health risks due to microgravity and prolonged bed rest, such as osteoporosis, venous thrombosis or pressure sores, are discussed.

[Adipose tissue: a real endocrine gland synthesizing hormones and cytokines: clinical implications]. / Le tissu adipeux: une véritable glande endocrine synthétisant hormones et cytokines: implications cliniques.

Adipose tissue (AT) is not considered anymore as a passive depot for storing excess energy in the form of triglycerides but as an active organ secreting several hormones or adipokines. With the exception of adiponectin the serum levels of adipokines are increased in obesity. Leptin regulates food intake, reproductive and immune system. Adiponectin decreases insulin resistance and has antiinflammatory properties. On the contrary, resisting, tumor necrosis factor and Interleukin-6 are diabetogenic and induce inflammatory reactions. It is believed that atherosclerosis is due to the inflammation induced by oxydized LDL-cholesterol in vessels. Abdominal obesity is associated with increased incidence of metabolic disorders and insulin resistance. The role of adipokines in these disorders is described as well as their role in the antidiabetic effect of thiazo-linedinediones. AT contains also enzymes responsible for the aromatization of androstenedione into estrone, which could explain an increase of breast and uterus cancer in obese people.

[Use of brain natriuretic peptide (BNP) in the diagnosis and treatment of heart failure]. / Utilité du dosage du peptide natriurétique de type B (BNP) dans le diagnostic et le traitement de l'insuffisance cardiaque.

Utility of the dosage of brain natriuretic factor (BNP) in the diagnosis and treatment of heart failure. Congestive heart failure (HF) is the main reason for hospitalisation of elderly patients. HF affects nearly 15% of patients aged 75 years or older. Prognosis after the diagnosis of HF is comparable to that of cancers with 50% survival after 4 years for mild HF and 50% after one year in more severe cases. Systolic HF defined by a left ventricular ejection fraction (LVEF) < 40% is asymptomatic in half the patients. In patients with symptomatic HF, LVEF is normal in almost 50% of the cases suggesting a diastolic HF. BNP is secreted after distension of left ventricule mainly in patients with systolic or diastolic HF, in proportion to the severity of the disease. A serum level of BNP > 100 pg/ml has a sensitivity of 90 percent and a specificity of 76 percent for the diagnosis of HF. Serum BNP is also increased in kidney insufficiency and in cirrhosis. BNP increase has a prognostic value to predict mortality after cardiac failure or myocardial infarction. Except for digoxin, all the drugs used to treat HF decrease serum levels of BNP. In dyspneic patients, serum levels of BNP < 50 pg/ml can exclude HF with a good probability. However BNP determination is not useful to diagnose HF in a general population.