Diagnosis and surgical treatment of prosthetic cardiac valve dysfunction

IMSP – Spitalul Clinic Republican, secţia Vicii Cardiace DobânditeNecătând la succesele obţinute în diagnosticul şi tratamentul disfuncţiilor de proteze valvulare, incidenţa lor rămâne a fi în creştere. Odată cu mărirea numărului de pacienţi operaţi şi posibilităţilor contemporane de diagnostic ne atenţionează aplicarea unor metode mai progresive de diagnostic şi tratament al acestor complicaţii severe, ca: deteriorarea structurală a protezei, disfuncţia nonstructurală, tromboză, endocardita de proteză şi evenimentele hemoragice la bolnavii care necesită anticoagulante. Recomandările din această lucrare sunt bazate pe standarde internaţionale şi pot fi aplicate de medici în diagnosticarea şi tratamentul medicamentos şi chirurgical în disfuncţiile protezelor valvulare cardiace.Heart valves have a simple open-and-close mechanism. Device effectiveness is easy to document. Although heart valve prosthesis has an excellent clinical performance, they also may have common complications (thromboembolism, thrombosis, bleeding, leak and infection). These complications are well known and easily to be detected. In this study we analyzed the disfunction of the heart valve prosthetics with the recommendation for early diagnosis and management

The Potential of N-Rich Plasma-Polymerized Ethylene (PPE:N) Films for Regulating the Phenotype of the Nucleus Pulposus

We recently developed a nitrogen-rich plasma-polymerized biomaterial, designated “PPE:N” (N-doped plasma-polymerized ethylene) that is capable of suppressing cellular hypertrophy while promoting type I collagen and aggrecan expression in mesenchymal stem cells from osteoarthritis patients. We then hypothesized that these surfaces would form an ideal substrate on which the nucleus pulposus (NP) phenotype would be maintained. Recent evidence using microarrays showed that in young rats, the relative mRNA levels of glypican-3 (GPC3) and pleiotrophin binding factor (PTN) were significantly higher in nucleus pulposus (NP) compared to annulus fibrosus (AF) and articular cartilage. Furthermore, vimentin (VIM) mRNA levels were higher in NP versus articular cartilage. In contrast, the levels of expression of cartilage oligomeric matrix protein (COMP) and matrix gla protein precursor (MGP) were lower in NP compared to articular cartilage. The objective of this study was to compare the expression profiles of these genes in NP cells from fetal bovine lumbar discs when cultured on either commercial polystyrene (PS) tissue culture dishes or on PPE:N with time. We found that the expression of these genes varies with the concentration of N ([N]). More specifically, the expression of several genes of NP was sensitive to [N], with a decrease of GPC3, VIM, PTN, and MGP in function of decreasing [N]. The expression of aggrecan, collagen type I, and collagen type II was also studied: no significant differences were observed in the cells on different surfaces with different culture time. The results support the concept that PPE:N may be a suitable scaffold for the culture of NP cells. Further studies are however necessary to better understand their effects on cellular phenotypes

Allosteric Regulation of Fibronectin/α5β1 Interaction by Fibronectin-Binding MSCRAMMs

Citation: Liang, X. W., Garcia, B. L., Visai, L., Prabhakaran, S., Meenan, N. A. G., Potts, J. R., . . . Hook, M. (2016). Allosteric Regulation of Fibronectin/alpha(5)beta(1) Interaction by Fibronectin-Binding MSCRAMMs. Plos One, 11(7), 17. doi:10.1371/journal.pone.0159118Adherence ofmicrobes to host tissues is a hallmark of infectious disease and is often mediated by a class of adhesins termed MSCRAMMs (Microbial Surface Components Recognizing Adhesive Matrix Molecules). Numerous pathogens express MSCRAMMs that specifically bind the heterodimeric human glycoprotein fibronectin (Fn). In addition to roles in adhesion, Fn-binding MSCRAMMs exploit physiological Fn functions. For example, several pathogens can invade host cells by a mechanism whereby MSCRAMM-bound Fn bridges interaction with alpha(5)beta(1) integrin. Here, we investigate two Fn-binding MSCRAMMs, FnBPA (Staphylococcus aureus) and BBK32 (Borrelia burgdorferi) to probe structure-activity relationships of MSCRAMM-induced Fn/alpha(5)beta(1) integrin activation. Circular dichroism, fluorescence resonance energy transfer, and dynamic light scattering techniques uncover a conformational rearrangement of Fn involving domains distant from the MSCRAMM binding site. Surface plasmon resonance experiments demonstrate a significant enhancement of Fn/alpha(5)beta(1) integrin affinity in the presence of FnBPA or BBK32. Detailed kinetic analysis of these interactions reveal that this change in affinity can be attributed solely to an increase in the initial Fn/alpha(5)beta(1) on-rate and that this rate-enhancement is dependent on high-affinity Fn-binding by MSCRAMMs. These data implicate MSCRAMM-induced perturbation of specific intramolecular contacts within the Fn heterodimer resulting in activation by exposing previously cryptic alpha(5)beta(1) interaction motifs. By correlating structural changes in Fn to a direct measurement of increased Fn/alpha(5)beta(1) affinity, this work significantly advances our understanding of the structural basis for the modulation of integrin function by Fn-binding MSCRAMMs

Amélioration des propriétés mécaniques de couches d’hydroxyapatite par mixage ionique à haute énergie

Les problèmes majeurs associés aux couches d’hydroxyapatite Hap [Ca10(PO4)6(OH)2] déposées par différents procédés sont liés aux faibles propriétés mécaniques, essentiellement l’adhésion du film sur son substrat métallique. Dans cette étude, nous étudions la possibilité d’utiliser le traitement de surface par implantation d’ions à haute énergie pour densifier la couche d’hydroxyapatite et augmenter son adhérence au substrat. Les films cristallins étudiés ont été déposés par ablation laser pulsé (PLD), à l’aide d’un laser de type Excimer KrF* (λ = 248 nm et τ ≤ 20 ns). Les films HA d’épaisseur environ 1 µm ont été déposés sur un substrat alliage de titane (Ti-5Al-2,5Fe) préalablement revêtu par une couche céramique de type TiN. La fonction essentielle de cette couche intermédiaire est d’empêcher toute diffusion d’éléments lourds contenus dans le substrat dans le corps humain. Les couches Hap et TiN déposées par PLD ont été traitées par implantation d’ions azote N+ avec une énergie E = 1 MeV. La densité de courant sur cible et la dose d’implantation ont été fixées constantes à 1 µA.cm-2 et 1016 at.cm-2. La topographie des couches a été caractérisée par microscopie confocale à champ étendu. Les propriétés mécaniques des couches ont été déterminées par indentation instrumentée, en mode quasi-statique et en mode rayure, à l’aide d’une pointe diamant de forme sphérique (R = 5 µm). Les premiers résultats montrent une augmentation des propriétés mécaniques (résistance à la pénétration, dureté et module élastique) des couches après implantation, aussi bien en mode statique qu’en mode dynamique. Cependant, on observe également une variation importante de la morphologie de la surface, en particulier au niveau de la rugosité. On note une relation entre morphologie de la surface et propriétés mécaniques, qui semble être également fonction de l’état local et des caractéristiques initiales de la couche Hap avant implantation (densité, porosité, épaisseur, taille des gouttelettes, rugosité)