Histamine,récepteurs de l’histamine et anti-histaminiques : données récentes

Histamine was discovered at the beginning of the 20th century. It has been recently shown that immunocompetent cells (T lymphocyte, dendritic cell) are capable of histamine synthesis and that histamine can regulate the Th1/Th2 balance. This immune regulation by histamine is related to its activity as a potent polarizing factor for dendritic cells, giving rise to DC2 dendritic cells that are involved in the differentiation of T helper cells towards Th2 phenotype. The majority of histamine is metabolized by N-methyltransferase. A common polymorphism of this enzyme that is associated with decreased enzyme activity has been associated with asthma. Histamine binds to four receptor types that are expressed on different types of cells and that mediate the numerous actions of histamine. H₁-receptors exhibit constitutive activity that is inhibited by several H₁-receptor antagonists, which therefore display a negative intrinsic activity called inverse agonist activity. In addition, the cerebral P-glycoprotein-mediated efflux of recent H₁-receptor antagonists may explain the lack of nervous system side effects of second-generation anti-histamines.     

Impact du risque coronarien et de l’hypertension sur le risque rénal en population générale

IntroductionAbnormal albuminuria (≥ 30 mg/g) and low estimated glomerular filtration rate (eGFR < 60 mL/min/1.73m²) not only are renal risk factors, but also cardiovascular and coronarian risk factors. Though, the relation between coronary risk and renal risk, and its interaction with insufficiently controlled brachial pressure (BP) is poorly described in the literature.Subjects and methodsWe realised a cross-sectional study on subjects 40 and older, having attended a medical exam in 11 IRSA centers between 2006 and 2010. Every subject filled a questionnaire, underwent biological analysis, and a clinical examination. eGFR and albuminuria were measured, and the 10-year risk of coronarian event was calculated (Laurier's equation)ResultsWe analysed 118 314 subjects, amongst whom 96 400 had no personal cardiovascular history. Amongst those, 9.1% had a 10-year coronary risk over 10%. There was a continuous relationship between coronary risk and renal risk: subjects with a risk above 15% had a significative risk of pathological albuminuria (OR: 6.87 [5.58–8.44]), and of low eGFR (2.26 [1.82–2.78]) compared to those with a risk under 5%. There was a continuous relationship between BP and renal risk, with a significative risk of pathological albuminuria (OR = 7.75 [6.69–8.96]) and of low eGFR (OR: 1.33 [1.09–1.60]) in subjects with BP greater than or equal to 180/110 mmHg, compared to those with normal BP.ConclusionIn the French population, 9.1% of subjects have a 10-year coronary risk above 10%. This risk is associated to abnormalities of the renal function. The relation between coronary risk and renal risk is continuous and dose-dependent, as is the relation between BP and renal risk.     

Fréquence de l’hypertension résistante aux traitements et indication à la dénervation rénale

ObjectiveTo evaluate in hypertensive patients followed in a specialized hypertension unit, the prevalence of subjects uncontrolled despite triple therapy including a diuretic. The aim is to estimate the percentage of hypertensive patients with an indication to renal denervation.MethodFrom a database of computerized medical records of a unit specialized in hypertension, it was extracted 144 consecutive cases of subjects treated and followed for at least 1 year and having had a home pressure monitoring (HPM) on treatment, and if necessary a work-up for a secondary hypertension. The blood pressure (BP) was evaluated in office by automated method (after 2 and 8 minutes) and with HPM (average of three measurements in the morning and evening for three consecutive days).ResultsThe population has the following characteristics: age 62 with 26% over 70 years, treated dyslipidemia (39%), treated diabetes (11%), adrenal hypertension treated medically (14%), severe renal failure (3%). The means of treatment are: a monotherapy (33%), bitherapy (35%), triple therapy (17%), quadritherapy (7%), pentatherapy or more (1%), spironolactone (45%), thiazide diuretics (49%). The uncontrolled hypertension was observed in 26% if the BP is evaluated with HPM, in 52% if the BP is evaluated at the office after 2 minutes of rest and 7% if the BP is evaluated after 8 minutes of rest (P < 0.01). In patients treated with at least a tritherapy in association with a diuretic, an uncontrolled hypertension was observed in 5% if the BP is evaluated with HPM. Failure to control for the SBP is the cause of 80% of resistant hypertension.ConclusionThe frequency of resistant hypertension is 5% of hypertensive patients followed in a specialized hypertension unit when guidelines are applied in the case of uncontrolled hypertension. These results indicate that the indication for renal denervation affects only a small percentage of patients treated for hypertension.     

Profil clinique et étiologique de l’hypertension artérielle maligne chez l’enfant en réanimation pédiatrique

IntroductionMalignant hypertension (HTA), pediatrics, is unique by its clinical presentation, defined as severe hypertension accompanied by ischemic failure of one or more organs.Methods-patientsRetroprospective study of cases of children admitted to pediatric intensive care. We chose a decline of 10 years from September 1994 to December 2004 for the first time, and from January 2005 to December 2015 for the second period; and we identified the cases presenting malignant hypertension (mHTA).ResultsSixty-six patients were included, a prevalence of 0.6%. The age of patients ranged from 12 months to 16 years. The symptoms are related to the consequences of hypertension or condition in question. The most found signs are headache in more than 7%. Cerebrovascular event in 6%. A hypertensive convulsive encephalopathy 33.3% of patients. Renal disease is common, of varying severity. A fundus retinopathy was found in 47% stage 3, stage 4 in 51%. mHTA defined for the mean SBP values of 175 mmHg and DBP average 112,5 mmHg is often secondary to renal causes. The treatment is symptomatic with antihypertensive associated with the etiological treatment. Evolution is good out of 7 deaths.ConclusionmHTA is a rare condition in the pediatric population. The clinical signs of functional rich under their impact on vital organs. The support must be early in intensive care.     

Indications de la désensibilisation en fonction des données épidémiologiques récentes

In most cases, hymenoptera venom allergy is caused by bees or wasps, but also occasionally by hornets, bumblebees or other members of the Vespidae family. The prevalence of sensitisation to venom in adults who have not had an allergic reaction following an insect sting but who have a positive skin test and/or specific IgE is estimated to be between 9.3% and 28.7%. The prevalence of systemic reactions in the general population reported in the literature ranges from 0.15% to 3.3%. The risk of having another systemic reaction following a subsequent sting depends on a number of factors: (1) the severity of the preceding reaction, (2) age, (3) the responsible insect, (4) occupation, (5) interval since the previous reaction. The risk of having a particularly severe reaction also depends on several other factors: the presence of cardiovascular disease, treatment with a beta-blocker, an elevated serum tryptase, and the presence of mastocytosis. The indications for venom immunotherapy in patients with positive skin and/or blood tests must take include consideration of the risk factors for a severe reaction with a new sting.