Search

Background An alarming rate of early failure has been recently reported for the LivaNova (previously Sorin) Mitroflow (LivaNova, London, UK) bioprosthesis. Here, we aimed at verifying if this possible underperformance is confirmed in a large, single-center experience and identifying the risk factors associated with early deterioration. Methods In all, 459 Mitroflow valves have been implanted from July 2009 to December 2013 (patients’ mean age 73 years; 204 women). Surviving patients have undergone yearly clinic and echocardiographic follow-up. Dysfunction was defined as moderate if the mean gradient was more than 30 mm Hg or severe if it exceeded 40 mm Hg. The population was divided on the basis of a dimensional mismatch, the model of the prosthesis (LX or DL: follow-up to 4 years), and patient’s age at the time of implantation. Results Cumulative freedom from moderate valve dysfunction was 81% ± 3% at 60 months. It was lower with patient-prosthesis mismatch (71% ± 5% versus 92% ± 3%; p = 0.0065) and with the more recent DL model (at 42 months: 78% ± 6% versus 96% ± 2%; p < 0.0001). Cumulative freedom from severe dysfunction was 93% ± 2% at 5 years. Again, it was inferior among patients with a mismatch (86% ± 4% versus 100%; p = 0.0013) and for the DL model (42 months: 92.5% ± 3% versus 98.5% ± 1%; p = 0.0309). Smaller prostheses showed higher rates of early degeneration. Conclusions The LivaNova Mitroflow valve appears to be prone to early deterioration. Smaller size prostheses should be used cautiously and avoided with patient-prosthesis mismatch. The DL model anticalcification treatment seems unable to prevent early degeneration, and possibly contributes to even earlier failure. [ABSTRACT FROM AUTHOR]

Calmodulin, regulatory, and essential myosin light chain are evolutionary conserved proteins that, by binding to IQ motifs of target proteins, regulate essential intracellular processes among which are efficiency of secretory vesicles release at synapsis, intracellular signaling, and regulation of cell division. The yeast Saccharomyces cerevisiae calmodulin Cmd1 and the essential myosin light chain Mlc1p share the ability to interact with the class V myosin Myo2p and Myo4 and the class II myosin Myo1p. These myosins are required for vesicle, organelle, and mRNA transport, spindle orientation, and cytokinesis. We have used the budding yeast model system to study how calmodulin and essential myosin light chain selectively regulate class V myosin function. NMR structural analysis of uncomplexed Mlc1p and interaction studies with the first three IQ motifs of Myo2p show that the structural similarities between Mlc1p and the other members of the EF-hand superfamily of calmodulin-like proteins are mainly restricted to the C-lobe of these proteins. The N-lobe of MIc1p presents a significantly compact and stable structure that is maintained both in the free and complexed states. The Mlc1p N-lobe interacts with the IQ motif in a manner that is regulated both by the IQ motifs sequence as well as by light chain structural features. These characteristic allows a distinctive interaction of Mlc1p with the first IQ motif of Myo2p when compared with calmodulin. This finding gives us a novel view of how calmodulin and essential light chain, through a differential binding to IQ1 of class V myosin motor, regulate this activity during vegetative growth and cytokinesis. [ABSTRACT FROM AUTHOR]

The Azotobacter vinelandii rhodanese is a 31 kDa sulfurtransferase protein that catalyzes the transfer of sulfur atom from thiosulfate to cyanide in the detoxification process from cyanide and is able to insert sulfur atom in the iron–sulfur cluster. A study of the uniformly 15N isotopic labeling by high resolution NMR, before obtaining the backbone sequential assignment, has been carried out. The sulfur loaded and the sulfur discharged forms of the enzyme show very similar HSQC spectra with a good spectral dispersion. Few resonances show changes in chemical shift between the two forms. Relaxation parameters T1, T2 and 1H–15N NOE of all amide nitrogen atoms, as well as isotope exchange kinetics, show that the two forms exhibit the same global correlation time and hydrodynamic properties. In parallel, essential dynamics studies show that formation and discharging of catalytic cysteine persulfide group has no significant impact on the overall conformation of the protein. These results, taken together, give a clearcut answer to the question if the catalytic mechanism of the enzyme involves a change in the conformation and/or in the mutual orientation of the two domains. On the contrary these results clearly indicate that upon the catalytic mechanism the two domains of the protein behave as a unique fold. [Copyright &y& Elsevier]

Focuses on the role of the glyoxalase system, which represents the main pathway for removal of cytotoxic methylglyoxal from cells, in controlling cell differentiation and proliferation. Two enzymes used by the system; Kinetics and mechanisms of reaction; Identification of zinc-binding motif.

Abstract: Liquid-encapsulated lysozyme microspheres were successfully synthesized using a sonochemical method. The encapsulation of four different liquids, namely, sunflower oil, tetradecane, dodecane and perfluorohexane on the formation, stability and morphology of the lysozyme microspheres was studied. Among the four different liquids used for encapsulation, perfluorohexane-filled microspheres were found to be most stable in the dried state with a narrow size distribution. In order to explore the possibility of encapsulating biofunctional molecules (e.g., drugs) within these microspheres, liquids containing a fluorescent dye (Nile red) were encapsulated and the ultrasound-induced release of these dye-loaded liquids was studied. The fluorescence data for the liquid-filled lysozyme microspheres demonstrated the potential use of the sonochemical technique for synthesizing these “vehicles” for the encapsulation and the controlled delivery of dyes, flavours, fragrances or drugs. [Copyright &y& Elsevier]

Hydrogels are good candidate materials for cell delivery scaffolds because they can mimic the physical, chemical, electrical and biological properties of most of the native tissues. In this study, composite biosynthetic hydrogels were produced by combining the bio-functionality of silk fibroin (SF) with the structural versatility of polyethylene-glycol-diacrylated (PEGDa). The formation of a photopolymerizable PEGDa-SF hydrogel (PSFHy) was optimized for 3D-cell culture. Functionalization of the 3D-PSFHy with protein microspheres (MS) was required to increase the porosity and cell-adhesive properties of the material. Cardiac mesenchymal stem cells, which were cultured within the MS - embedding PSFHy, exhibited good viability and expression of proteins that are characteristic of the initial phases of the cardiac muscle differentiation process. Further, the addition of chondroitin sulfate into the scaffolds improved the cell viability. A cell-preconditioning of the scaffold was also performed, suggesting a potential application of these sponge-like scaffolds for analysing the effects of several extracellular microenvironments, produced by different kinds of cells, on the stem cells fate. The results presented herein highlight on the possibility to use the PSFHys functionalized with MS as stem cell-carrier systems with sponge-like properties, potential ultrasound-imaging contrast agents and controlled biochemical factor delivery. [ABSTRACT FROM AUTHOR]

The reprocessing of vegetal-waste represents a new research field in order to design novel biomaterials for potential biomedical applications and in food industry. Here we obtained a biomaterial from Lupinus albus L. hull (LH) that was characterized micro-structurally by scanning electron microscopy and for its antimicrobial and scaffolding properties. A good adhesion and proliferation of human mesenchymal stem cells (hMSCs) seeded on LH scaffold were observed. Thanks to its high content of cellulose and beneficial phytochemical substances, LH and its derivatives can represent an available source for fabrication of biocompatible and bioactive scaffolds. Therefore, a reprocessing protocol of LH was optimized for producing a new LH bioplastic named BPLH. This new biomaterial was characterized by chemico-physical analyses. The water uptake, degradability and antimicrobial properties of BPLH were evaluated, as well as the mechanical properties. A good adhesion and proliferation of both fibroblasts and hMSCs on BPLH were observed over 2 weeks, and immunofluorescence analysis of hMSCs after 3 weeks indicates an initial commitment toward muscle differentiation. Our work represents a new approach toward the recovery and valorization of the vegetal waste showing the remarkable properties of LH and BPLH as cellular waste-based scaffold with potential applications in cell-based food field as well as in medicine for topical patches in wound healing and bedsores treatment. [ABSTRACT FROM AUTHOR]

To investigate structural relationship between amphibian and mammalian GSTs the complete amino acid sequence of the major form of glutathione transferase present in toad liver (Bufo bufo) was determined. The enzyme subunit is composed of 210 amino acid residues corresponding to a molecular mass of 24,178 Da. In comparison with the primary structure of amphibian bbGSTP1-1, toad liver GST showed 54% sequence identity. On the other hand, toad liver GST showed about 45–55% sequence identity when compared with other pi class GST and less then 25% identity with GST of other classes. Amino acid residues involved in the H site and in the key and lock structure of the toad enzyme are significantly different from those of bbGSTP1-1 and other mammalian pi class GST. On the basis of its structural and immunological properties the toad liver GST, indicated as bbGSTP2-2, could represent the prototype of a subset of the pi family. [Copyright &y& Elsevier]