Dephosphorylated-uncarboxylated Matrix Gla protein concentration is predictive of vitamin K status and is correlated with vascular calcification in a cohort of hemodialysis patients.

Background: Matrix Gla protein (MGP) is known to act as a potent local inhibitor of vascular calcifications. However, in order to be active, MGP must be phosphorylated and carboxylated, with this last process being dependent on vitamin K. The present study focused on the inactive form of MGP (dephosphorylated and uncarboxylated: dp-ucMGP) in a population of hemodialyzed (HD) patients. Results found in subjects being treated or not with vitamin K antagonist (VKA) were compared and the relationship between dp-ucMGP levels and the vascular calcification score were assessed. Methods: One hundred sixty prevalent HD patients were enrolled into this observational cohort study, including 23 who were receiving VKA treatment. The calcification score was determined (using the Kauppila method) and dp-ucMGP levels were measured using the automated iSYS method. Results: dp-ucMGP levels were much higher in patients being treated with VKA and little overlap was found with those not being treated (5604 [3758; 7836] vs. 1939 [1419; 2841] pmol/L, p <0.0001). In multivariate analysis, treatment with VKA was the most important variable explaining variation in dp-ucMGP levels even when adjusting for all other significant variables. In the 137 untreated patients, dp-ucMGP levels were significantly (p < 0.05) associated both in the uni- and multivariate analysis with age, body mass index, plasma levels of albumin, C-reactive protein, and FGF-23, and the vascular calcification score. Conclusion: We confirmed that the concentration of dp-ucMGP was higher in HD patients being treated with VKA. We observed a significant correlation between dp-ucMGP concentration and the calcification score. Our data support the theoretical role of MGP in the development of vascular calcifications. We confirmed the potential role of the inactive form of MGP in assessing the vitamin K status of the HD patients

Micromechanical Properties of Injection-Molded Starch–Wood Particle Composites

The micromechanical properties of injection molded starch–wood particle composites were investigated as a function of particle content and humidity conditions. The composite materials were characterized by scanning electron microscopy and X-ray diffraction methods. The microhardness of the composites was shown to increase notably with the concentration of the wood particles. In addition,creep behavior under the indenter and temperature dependence were evaluated in terms of the independent contribution of the starch matrix and the wood microparticles to the hardness value. The influence of drying time on the density and weight uptake of the injection-molded composites was highlighted. The results revealed the role of the mechanism of water evaporation, showing that the dependence of water uptake and temperature was greater for the starch–wood composites than for the pure starch sample. Experiments performed during the drying process at 70°C indicated that the wood in the starch composites did not prevent water loss from the samples.Peer reviewe

La mesure de la pression artérielle ambulatoire:un outil ou un jouet?

peer reviewedLa mesure ambulatoire de la pression artérielle sur des périodes de 12 à 24 heures permet de mieux définir l'existence et la sévérité d'une hypertension artérielle et ainsi de prédire avec plus de précision dans quelle mesure cette hypertension constitue un facteur de risque cardio-vasculaire. Cette technique permet ainsi de sélectionner les patients qui justifient une thérapeutique médicamenteuse, et parailleurs, de contrôler l'efficacité de ces traitements

Mature erythrocyte parameters as new markers of functional iron deficiency in haemodialysis: sensitivity and specificity

Background. The percentage of hypochromic red blood cells (RBCs) (%HYPO) has been demonstrated as the best predictor of response to iron loading in haemodialysis patients treated with recombinant human erythropoietin (rHuEPO). However, we have previously shown that this parameter is positively influenced by erythropoietic activity since reticulocytes are considered hypochromic by cell counters. New cell counters are able to determine cell volume and haemoglobin (Hb) concentration separately on reticulocytes and mature erythrocytes. The aim of this study was to assess the sensitivity and specificity of mature erythrocyte parameters in detecting functional iron deficiency (FID). Methods. A total of 32 stable chronic haemodialysis patients in the maintenance phase of rHuEPO therapy were included. Classical parameters of iron monitoring and mature erythrocyte parameters were measured after a 4-week iron-free period. Patients were classified as responders (R) or non-responders (NR) to an iron load of 100 mg iron sucrose at each dialysis session for 4 weeks, according to whether their Hb increased by >1 g/dl at the end of iron loading. Results. Twelve patients were identified as responders. Receiver operating characteristic (ROC) curve analysis demonstrated %HYPO and its corresponding parameter on mature erythrocyte, %HYPOm, as the best predictors of FID. The other parameters were ordered as follows: tranferrin saturation (TSAT), ferritin (FRT), mature RBC Hb content (CHm), mean corpuscular Hb concentration (MCHC), percentage of mature erythrocytes with a low CHm (%lowCHm), mean content in Hb (MCH) and reticulocyte Hb content CHr. Comparing the parameters at different cut-offs, the best sensitivity, specificity and efficiency were demonstrated for HYPOm>6%. Conclusion. The best efficiency to predict FID was found for %HYPOm>6%. The predictive value of %HYPO was quite similar. The clinical impact of %HYPOm in iron monitoring should also be tested in the induction phase of rHuEPO treatment because of its independence from erythropoietic activity

Stratégie actuelle du traitement de l'hypertension artérielle

peer reviewedL'identification de l'hypertension artérielle en tant que facteur de risque de morbidité et de mortalité cardio-vasculaire a notablement modifié l'attitude du corps médical dans le choix et la conduite du traitement antihypertenseur. Cette observation, associée à l'apparition d'antihypertenseurs mieux tolérés et d'un maniement plus facile, a incité à traiter des hypertensions de plus en plus légères. Le but de ce traitement n'est cependant pas de faire baisser la pression artérielle, mais de réduire la morbidité et la 'mortalité cardio-vasculaires. De nombreuses études thérapeutiques publiées ces dix dernières années ont permis d'évaluer l'efficacité de cette approche thérapeutique. Dans une première partie, nous résumerons les données cliniques et expérimentales concernant les relations entre hypertension et mortalité cardio-vasculaire; nous aborderons ensuite les conclusions des études thérapeutiques qui illustrent l'efficacité de la correction de la pression artérielle dans l'hypertension sévère et modérée, mais ne fournissent que des résultats assez ambigus concernant l'hypertension légère, variété clinique la plus fréquente. Cet échec relatif des drogues antihypertensives à influencer la morbidité et la mortalité cardio-vasculaires dans l'hypertension a entraîné un regain d'intérêt pour les traitements non pharmacologiques. La seconde partie est essentiellement consacrée à une revue des possibilités et des limites de ces traitements, dont les plus efficaces restent les mesures diététiques. Les grandes études thérapeutiques ont par ailleurs fait ressortir la difficulté de la définition même de l'hypertension artérielle. La mesure clinique de la pression artérielle est difficile en particulier en raison de la variabilité de ce paramètre. Cette difficulté à définir l'hypertension artérielle explique probablement en partie l'échec relatif du traitement antihypertenseur.,Beaucoup des patients traités ne sont en fait pas hypertendus. La dernière partie résumera notre expérience de l'enregistrement de la pression artérielle ambulatoire sur des périodes prolongées. Cette approche encore imparfaite, devrait améliorer notre définition du sujet hypertendu et ainsi permettre de mieux sélectionner le patient susceptible de tirer avantage du traitement antihypertenseur. D'autres questions restent à l'étude et ne seront pas abordées dans cette réunion, par exemple l'importante question de savoir si certaines drogues sont plus efficaces que d'autres dans la prévention des complications cardio-vasculaires

Does Dopamine Play a Role in Renal Anomaly in Sodium Excretion, a Marker for Hereditary Predisposition to Arterial Hypertension?

peer reviewedSince Dahl's observation, a renal defect os sodium excretion is proposed as one of pathogenetic mechanism of hypertension (HTA). Our study has tried to verify this concept in 20 young normotensives with (n = 12) and without (n = 8) familial predisposition to HTA, allowing to test the genetic transmission of such potential renal abnormality of sodium balance. Each people was submitted to 3 different Na diet (20, 170 and 340 mM NaCl) each for 1 week. At each visit, blood pressure, vascular resistances, biological values were determined at rest (plasma renin activity, creatinine clearance, 24 hours before the test, catecholamines, aldosterone and ion urinary excretion). Then 1 liter of isotonic saline was perfused in 30 minutes with measures of blood pressure and 3 hours urinary dopamine and Na excretion. During the low and medium Na diets, but not during the high Na diet, the natriuresis and dopamine excretion were lower in the 3 hour urine collection in patients with a family history of HTA (p less than 0.02 and p less than 0.005, respectively). No other clinical or biological difference was noted between the 2 groups. Thus, genetic hypertensive predisposition seems to be characterized by a lower Na excretion during acute Na loading in normal or depleted Na diet, linked to an impaired urinary dopamine excretion. These findings suggest that the defect responsible for the susceptibility to sodium intake is at the kidney level. Some dopamine agonists would be of great therapeutical value in treating such patients when blood pressure begins to rise

Does Ambulatory Blood Pressure Measurement Allow a Better Definition of Arterial Hypertension?

The lack of effect of treatment of mild hypertension on the coronary heart disease has motivated researches for a better diagnosis of hypertension. One of the approaches presently under study uses the recording of ambulatory blood pressure using semi-automatic devices. The usefulness of these apparatus is however restricted by the lack of reference values recorded in normotensive control patients. We have recorded ambulatory blood pressure (PAA) in 24 normotensives, 22 untreated hypertensives and 45 treated hypertensive patients, and compared the data obtained to the blood pressure recorded during medical examination (PAC). If a good correlation is usually observed between PAA and PAC, very large and unpredictable discordances are frequently observed. No correlation is found between the difference PAA-PAC and the variability of PAA. This variability does not fully explain the difference observed between PAA and PAC. This variability expressed in mmHg increases with age and the level of BP. Ambulatory BP appears to be a very reproducible value which may allow to improve the definition of hypertension and therefore the cardiovascular risk