Recombinant Fibrinogen Vlissingen/Frankfurt IV: THE DELETION OF RESIDUES 319 AND 320 FROM THE γ CHAIN OF FIBRINOGEN ALTERS CALCIUM BINDING, FIBRIN POLYMERIZATION, CROSS-LINKING, AND PLATELET AGGREGATION

We synthesized a variant, recombinant fibrinogen modeled after the heterozygous dysfibrinogen Vlissingen/Frankfurt IV, a deletion of two residues, gammaAsn-319 and gammaAsp-320, located within the high affinity calcium-binding pocket. Turbidity studies showed no evidence of fibrin polymerization, although size exclusion chromatography, transmission electron microscopy, and dynamic light scattering studies showed small aggregates. These aggregates did not resemble normal protofibrils nor did they clot. Fibrinopeptide A release was normal, whereas fibrinopeptide B release was delayed approximately 3-fold. Plasmin cleavage of this fibrinogen was not changed by the presence of calcium or Gly-Pro-Arg-Pro, indicating that both the calcium-binding site and the "a" polymerization site were non-functional. We conclude that the loss of normal polymerization was due to the lack of "A-a" interactions. Moreover, functions associated with the C-terminal end of the gamma chain, such as platelet aggregation and factor XIII cross-linking, were also disrupted, suggesting that this deletion of two residues affected the overall structure of the C-terminal domain of the gamma chain

Transcatheter heart valve commissural alignment: an updated review

Transcatheter aortic valve replacement (TAVR) indications recently extended to lower surgical risk patients with longer life expectancy. Commissural alignment (CA) is one of the emerging concepts and is becoming one of the cornerstones of the TAVR procedure in a patient with increased longevity. Indeed, CA may improve transcatheter heart valve (THV) hemodynamics, future coronary access, and repeatability. The definition of CA has been recently standardized by the ALIGN-TAVR consortium using a four-tier scale based on CT analysis. Progress has been made during the index TAVR procedure to optimize CA, especially with self-expandable platforms. Indeed, specific delivery catheter orientation, THV rotation, and computed-tomography-derived views have been proposed to achieve a reasonable degree of CA. Recent data demonstrate feasibility, safety, and a significant reduction in coronary overlap using these techniques, especially with self-expandable platforms. This review provides an overview of THV CA including assessment methods, alignment techniques during the index TAVR procedure with different THV platforms, the clinical impact of commissural misalignment, and challenging situations for CA

A review on boiling heat transfer enhancement with nanofluids

There has been increasing interest of late in nanofluid boiling and its use in heat transfer enhancement. This article covers recent advances in the last decade by researchers in both pool boiling and convective boiling applications, with nanofluids as the working fluid. The available data in the literature is reviewed in terms of enhancements, and degradations in the nucleate boiling heat transfer and critical heat flux. Conflicting data have been presented in the literature on the effect that nanofluids have on the boiling heat-transfer coefficient; however, almost all researchers have noted an enhancement in the critical heat flux during nanofluid boiling. Several researchers have observed nanoparticle deposition at the heater surface, which they have related back to the critical heat flux enhancement

Criblage d\'inducteurs de réactions de défense chez le blé (Triticum aestivum) contre l\'oïdium (Blumeria graminis f.sp. tritici)

Cette étude a consisté à rechercher des substances biologiques capables d\'induire les défenses naturelles du blé (Triticum aestivum) contre l\'oïdium (Blumeria graminis f.sp. tritici (Bgt)). Des fractions non purifiées dérivées de la plante et/ou des agents pathogènes du blé (broyats foliaires de blé ou de spores de Bgt, hydrolysat du mycélium de Septoria nodorum (Sn)) ainsi que des produits purifiés (tréhalose et salicylate d\'heptanoyle (SH)) ont été testés lors d\'un traitement préventif. L\'intensité des protections obtenues a varié en fonction de la nature et de la concentration du produit utilisé. La protection obtenue lors de la pulvérisation du broyat foliaire de blé non infecté a été inférieure (33 %) à celle enregistrée après pulvérisation d\'un broyat foliaire de blé infecté par Bgt (46 %). La protection obtenue, suite à la pulvérisation de la plante avec une suspension de spores de Bgt inactivées, a été de 44 %. La diminution d\'infection enregistrée après pulvérisation d\'un hydrolysat de mycélium d\'un autre agent pathogène foliaire du blé (Sn) a été de 33 %. Alors que des pulvérisations préventives de tréhalose à des concentrations de 10 et 15 g/l sur des plants de blé entraînent des diminutions de l\'infection de 50 à 60 %, des concentrations de 1 et 5 g/l ne permettent d\'enregistrer aucune protection. La pulvérisation préventive de deux autres diholosides, le maltose et le cellobiose à 15 g/l ne permet pas de déceler une protection. Le traitement préventif du blé par le SH a permis d\'obtenir une protection très forte (80 %) pour de faibles concentrations en produit (0,1 g/l). L\'application de chacun des deux constituants de la molécule pris séparément induit une protection 2 fois plus faible que celle du SH avec l\'acide salicylique (AS) et aucune protection avec l\'acide heptanoïque (AH).Wheat powdery mildew, caused by Blumeria graminis f. sp. tritici (Bgt), is one of the most damaging diseases of wheat (Triticum aestivum) especially in Northern France. The study was aiming at screening biological molecules of fungal or plant origin that could enhance resistance to powdery mildew in wheat as an alternative to chemical fungicides. The protection confered by several non purified fractions originating from leaves of wheat (contaminated or not with Bgt) or from the pathogen agents (Bgt and Septoria nodorum (Sn)) were assessed. Protection obtained after treatment with no infected wheat leaves was less important (33 %) than with infected leaves (46 %). The protection recorded after application of inactivated Bgt spores or Sn were about 44 and 33 % respectively. Two other purified molecules, trehalose and heptanoyl salicylic acid (HS), were selected because of their nontoxicity to the environment. Treatment of wheat leaves with the different substances, prior to fungal inoculation, resulted in different levels of protection against Bgt depending on the nature and the concentrations used. The treatment with HS at low concentration (0,1 g/l) allowed a high protection reaching 80 %. Whereas trehalose at 10 and 15 g/l reduced the infection by 50 and 60 % respectively, no protection was observed at 1 and 5 g/l. Keywords: Blé, Blumeria graminis f.sp. tritici, oïdium, inducteurs de défense naturelle, résistance acquise.Agronomie Africaine Vol. 20 (2) 2008: pp. 191-19