Dominance of positivity of the Green's function associated to a perturbed polyharmonic dirichlet boundary value problem by pointwise estimates

Magdeburg, Univ., Fak. für Mathematik, Diss., 2015

La fonction rénale sous inhibition de l'enzyme de conversion de l'angiotensine [Renal function after administration of angiotensin-converting enzyme inhibitors]

Angiotensin converting enzyme (ACE) inhibitors are widely used today for the management of hypertension and congestive heart failure. These agents inhibit angiotensin II synthesis. In some particular circumstances they may be responsible for deterioration of renal function, e.g. in hypertensive patients with bilateral renal artery stenosis or with stenosis of the artery supplying a single kidney, or in patients with severe congestive heart failure or marked nephroangiosclerosis. In these patients renal perfusion pressure may become too low to maintain adequate glomerular filtration as there remains no angiotensin II to increase the tone of the efferent arteriole. In high risk patients it is therefore recommended that serum creatinine be checked after initiating therapy with an ACE inhibitor.

Deux extensions de Théorèmes de Hamburger (portant sur l'équation fonctionnelle de la fonction dzêta)

We propose two types of extensions to Hamburger’s theorems on the Dirichlet series with functional equation like the one of the Riemann zeta function, under weaker hypotheses. This builds upon the dictionary betweeen the moderate meromorphic functions with functional equation and the tempered distributions with extended S-support condition.

Dysfonction endothéliale et risque cardiovasculaire : l'exercice protège la fonction endothéliale et prévient la maladie cardiovasculaire [Endothelial dysfunction and cardiovascular risk : xercise protects endothelial function and prevents cardiovascular disease]

Objectifs : Décrire les caractéristiques de la dysfonction endothéliale associée au risque cardiovasculaire et expliciter les mécanismes biologiques par lesquels l'exercice stimule et/ou restaure la fonction endothéliale. Actualités : La fonction endothéliale, via les effets vasculoprotecteurs du monoxyde d'azote (NO), préserve la santé cardiovasculaire. Le dysfonctionnement endothélial est un facteur prédictif de la survenue des événements cardiovasculaires. L'endothélium est donc un organe cible préventif et thérapeutique prioritaire pour diminuer le risque cardiovasculaire. Perspectives : Les études épidémiologiques mettent en évidence les bienfaits de l'exercice régulier sur la fonction endothéliale, via une action endothéliale directe. L'approche expérimentale permet aujourd'hui de mieux cerner les mécanismes biologiques protecteurs de l'exercice. L'exercice, via l'élévation des forces de cisaillement, protège et/ou normalise la fonction endothéliale en augmentant la biodisponibilité en NO soit par une stimulation de la production de NO et/ou, soit par une augmentation des défenses antioxydantes et/ou une atténuation des enzymes prooxydantes. Conclusion : La connaissance des mécanismes biologiques protecteurs de l'exercice doit permettre d'encourager la pratique d'un exercice régulier par tous pour prévenir et réduire la mortalité cardiovasculaire.

Estimation de la fonction rénale par l'equation MDRD: intérêt et limites pour l'adaptation des doses de médicaments [Renal function estimation by MDRD equation: interest and limitations for drug dosing].

The MDRD (Modification of diet in renal disease) equation enables glomerular filtration rate (GFR) estimation from serum creatinine only. Thus, the laboratory can report an estimated GFR (eGFR) with each serum creatinine assessment, increasing therefore the recognition of renal failure. Predictive performance of MDRD equation is better for GFR < 60 ml/min/1,73 m2. A normal or near-normal renal function is often underestimated by this equation. Overall, MDRD provides more reliable estimations of renal function than the Cockcroft-Gault (C-G) formula, but both lack precision. MDRD is not superior to C-G for drug dosing. Being adjusted to 1,73 m2, MDRD eGFR has to be back adjusted to the patient's body surface area for drug dosing. Besides, C-G has the advantage of a greater simplicity and a longer use.

Cross-species analysis of the replication complex of Old World arenaviruses reveals two nucleoprotein sites involved in L protein function.

Lassa virus (LASV) causing hemorrhagic Lassa fever in West Africa, Mopeia virus (MOPV) from East Africa, and lymphocytic choriomeningitis virus (LCMV) are the main representatives of the Old World arenaviruses. Little is known about how the components of the arenavirus replication machinery, i.e., the genome, nucleoprotein (NP), and L protein, interact. In addition, it is unknown whether these components can function across species boundaries. We established minireplicon systems for MOPV and LCMV in analogy to the existing LASV system and exchanged the components among the three systems. The functional and physical integrity of the resulting complexes was tested by reporter gene assay, Northern blotting, and coimmunoprecipitation studies. The minigenomes, NPs, and L proteins of LASV and MOPV could be exchanged without loss of function. LASV and MOPV L protein was also active in conjunction with LCMV NP, while the LCMV L protein required homologous NP for activity. Analysis of LASV/LCMV NP chimeras identified a single LCMV-specific NP residue (Ile-53) and the C terminus of NP (residues 340 to 558) as being essential for LCMV L protein function. The defect of LASV and MOPV NP in supporting transcriptional activity of LCMV L protein was not caused by a defect in physical NP-L protein interaction. In conclusion, components of the replication complex of Old World arenaviruses have the potential to functionally and physically interact across species boundaries. Residue 53 and the C-terminal domain of NP are important for function of L protein during genome replication and transcription.

The effect of L-arginine on guinea-pig and rabbit airway smooth muscle function in vitro

We have investigated the effects of L-arginine, D-arginine and L-lysine on airway smooth muscle responsiveness to spasmogens in vitro. Both L-arginine and D-arginine (100 mM) significantly reduced the contractile potency and maximal contractile response to histamine but not to methacholine or potassium chloride in guinea-pig epithelium-denuded isolated trachea. Similarly, the contractile response to histamine was significantly reduced by L-arginine (100 mM) in rabbit epithelium-denuded isolated bronchus. The amino acid L-lysine (100 mM) failed to significantly alter the contractile potency of histamine in guinea-pig isolated trachea (P>0.05). In guinea-pig isolated trachea precontracted with histamine, both L-arginine and D-arginine produced a concentration-dependent relaxation which was not significantly altered by epithelium removal or by the presence of the nitric oxide synthase inhibitor, NG-nitro L-arginine methyl ester (L-NAME; 50 µM). Thus, at very high concentrations, arginine exhibit a non-competitive antagonism of histamine-induced contraction of isolated airway preparations that was independent of the generation of nitric oxide and was not dependent on charge. These observations confirm previous studies of cutaneous permeability responses and of contractile responses of guinea-pig isolated ileal smooth muscle. Taken together, the data suggest that high concentrations of arginine can exert an anti-histamine effect.

Ω-results for Beurling's zeta function and lower bounds for the generalised Dirichlet divisor problem

In this paper we study generalised prime systems for which the integer counting function NP(x) is asymptotically well behaved, in the sense that NP(x)=ρx+O(xβ), where ρ is a positive constant and . For such systems, the associated zeta function ζP(s) is holomorphic for . We prove that for , for any ε>0, and also for ε=0 for all such σ except possibly one value. The Dirichlet divisor problem for generalised integers concerns the size of the error term in NkP(x)−Ress=1(ζPk(s)xs/s), which is O(xθ) for some θ<1. Letting αk denote the infimum of such θ, we show that .

The effect of L-arginine on guinea-pig and rabbit airway smooth muscle function in vitro

We have investigated the effects of L-arginine, D-arginine and L-lysine on airway smooth muscle responsiveness to spasmogens in vitro. Both L-arginine and D-arginine (100 mM) significantly reduced the contractile potency and maximal contractile response to histamine but not to methacholine or potassium chloride in guinea-pig epithelium-denuded isolated trachea. Similarly, the contractile response to histamine was significantly reduced by L-arginine (100 mM) in rabbit epithelium-denuded isolated bronchus. The amino acid L-lysine (100 mM) failed to significantly alter the contractile potency of histamine in guinea-pig isolated trachea (P>0.05). In guinea-pig isolated trachea precontracted with histamine, both L-arginine and D-arginine produced a concentration-dependent relaxation which was not significantly altered by epithelium removal or by the presence of the nitric oxide synthase inhibitor, NG-nitro L-arginine methyl ester (L-NAME; 50 µM). Thus, at very high concentrations, arginine exhibit a non-competitive antagonism of histamine-induced contraction of isolated airway preparations that was independent of the generation of nitric oxide and was not dependent on charge. These observations confirm previous studies of cutaneous permeability responses and of contractile responses of guinea-pig isolated ileal smooth muscle. Taken together, the data suggest that high concentrations of arginine can exert an anti-histamine effect.

Change in the ascorbic-acid content of acerolas (Malpighia-glabra L) as function of harvest maturation degree and storage-temperature

The content of ascorbic acid was assayed in acerolas harvested in three phases of maturation: green-yellow fruits (I); light red (II) and wine-coloured (III). Phase I and Phase II fruit were packed in aluminium sheets and stoppered flasks and stored in freezer (-10o.C) and in refrigerator (8o.C). Samples of 8 fruits from each experimental condiction were analysed for ascorbic acid determination by 2-chlorophenol indophenol discolouration method. The averages of 1.393,5 mg./100g. for Phase I sample, 1024,9 for Phase II and 756,5 for Phase III fruits, showed a statistically significative linear decreasing of the ascorbic acid content related with the maturation extent Phase I samples stored in freezing showed statitically significative decreasing of that vitamin at 408 hours of storage in both: aluminium sheet and stoppered flask package; in chilling temperature there was significative reduction of ascorbic acid content after 240 and 312 hours, respectively, for fruits packed in aluminium sheet and stopped flasks. Phase Il samples showed significative lost at 72 hours of storage when maintained in freezing temperature either, in aluminium sheet or in stoppered flasks: When stored in chilling temperature showed progressive lost of ascorbic acid in all measuring periods in every package. After 144 hours suffered deterioration suggested by colour changes.

The 3D structure and function of digestive cathepsin L-like proteinases of Tenebrio molitor larval midgut

Cathepsin L-like proteinases (CAL) are major digestive proteinases in the beetle Tenebrio molitor. Procathepsin Ls 2 (pCAL2) and 3 (pCAL3) were expressed as recombinant proteins in Escherichia coil, purified and activated under acidic conditions. Immunoblot analyses of different T. molitor larval tissues demonstrated that a polyclonal antibody to pCAL3 recognized pCAL3 and cathepsin L 3 (CAD) only in the anterior two-thirds of midgut tissue and midgut luminal contents of T. molitor larvae. Furthermore, immunocytolocalization data indicated that pCAL3 occurs in secretory vesicles and microvilli in anterior midgut Therefore CAL3, like cathepsin L 2 (CAL2), is a digestive enzyme secreted by T. molitor anterior midgut CAD hydrolyses Z-FR-MCA and Z-RR-MCA (typical cathepsin substrates), whereas CAL2 hydrolyses only Z-FR-MCA. Active site mutants (pCAL2C25S and pCAL3C265) were constructed by replacing the catalytic cysteine with serine to prevent autocatalytic processing. Recombinant pCAL2 and pCAL3 mutants (pCAL2C25S and pCAL3C26S) were prepared, crystallized and their 3D structures determined at 1.85 and 2.1 angstrom, respectively. While the overall structure of these enzymes is similar to other members of the papain superfamily, structural differences in the S2 subsite explain their substrate specificities. The data also supported models for CAL trafficking to lysosomes and to secretory vesicles to be discharged into midgut contents. (C) 2012 Elsevier Ltd. All rights reserved.

Chronic Stress Improves the Myocardial Function without Altering L-type Ca+2 Channel Activity in Rats

Background: Chronic stress is associated with cardiac remodeling; however the mechanisms have yet to be clarified. Objective: The purpose of this study was test the hypothesis that chronic stress promotes cardiac dysfunction associated to L-type calcium Ca2+ channel activity depression. Methods: Thirty-day-old male Wistar rats (70 - 100 g) were distributed into two groups: control (C) and chronic stress (St). The stress was consistently maintained at immobilization during 15 weeks, 5 times per week, 1h per day. The cardiac function was evaluated by left ventricular performance through echocardiography and by ventricular isolated papillary muscle. The myocardial papillary muscle activity was assessed at baseline conditions and with inotropic maneuvers such as: post-rest contraction and increases in extracellular Ca2+ concentration, in presence or absence of specific blockers L-type calcium channels. Results: The stress was characterized for adrenal glands hypertrophy, increase of systemic corticosterone level and arterial hypertension. The chronic stress provided left ventricular hypertrophy. The left ventricular and baseline myocardial function did not change with chronic stress. However, it improved the response of the papillary muscle in relation to positive inotropic stimulation. This function improvement was not associated with the L-type Ca2+ channel. Conclusion: Chronic stress produced cardiac hypertrophy; however, in the study of papillary muscle, the positive inotropic maneuvers potentiated cardiac function in stressed rats, without involvement of L-type Ca2+ channel. Thus, the responsible mechanisms remain unclear with respect to Ca2+ influx alterations. (Arq Bras Cardiol 2012;99(4):907-914)