Chemotactic and Angiogenic Potential of Mineralized Collagen Scaffolds Functionalized with Naturally Occurring Bioactive Factor Mixtures to Stimulate Bone Regeneration

To develop cost-effective and efficient bone substitutes for improved regeneration of bone defects, heparin-modified mineralized collagen scaffolds were functionalized with concentrated, naturally occurring bioactive factor mixtures derived from adipose tissue, platelet-rich plasma and conditioned medium from a hypoxia-treated human bone marrow-derived mesenchymal stem cell line. Besides the analysis of the release kinetics of functionalized scaffolds, the bioactivity of the released bioactive factors was tested with regard to chemotaxis and angiogenic tube formation. Additionally, functionalized scaffolds were seeded with human bone marrow-derived mesenchymal stromal cells (hBM-MSC) and their osteogenic and angiogenic potential was investigated. The release of bioactive factors from the scaffolds was highest within the first 3 days. Bioactivity of the released factors could be confirmed for all bioactive factor mixtures by successful chemoattraction of hBM-MSC in a transwell assay as well as by the formation of prevascular structures in a 2D co-culture system of hBM-MSC and human umbilical vein endothelial cells. The cells seeded directly onto the functionalized scaffolds were able to express osteogenic markers and form tubular networks. In conclusion, heparin-modified mineralized collagen scaffolds could be successfully functionalized with naturally occurring bioactive factor mixtures promoting cell migration and vascularization.     

Characterization of crystalline alumina films formed in alcohol-water solutions

Crystalline aluminum hydrous oxide [γ-AlO(OH)] thin films were prepared by hydration of a high cubicity tunnel-etched Al foil in alcohol—DI-water solutions at 95 °C for times up to 1 h. Presence of free molecular water was found to be an absolute requirement for film formation. In addition, the type of alcohol used in the hydration environment, n-propyl alcohol, ethylene glycol or glycerol, influenced the hydration kinetics, i.e. the induction time for film growth. Denser and low porosity films were suggested by field emission—scanning electron microscopy analysis. X-Ray diffraction showed the presence of only one crystalline phase identified as pseudoboehmite.     

Epstein-Barr virus transmission from a blood donor to an organ transplant recipient with recovery of the same virus strain from the recipient's blood and oropharynx

A previous study (Savoie et al, Blood 83:2715, 1994) identified eight transplant patients who acquired Epstein-Barr virus (EBV) infection during the peritransplant period. Three of these patients subsequently developed B-cell lymphoproliferative disease within 4 months of transplantation. Among these, there was a 16-year-old liver transplant patient who was negative for EBV at the time of transplant and who received an EBV-negative organ. After transplant, this patient was transfused with 9 U of packed red blood cells. Eight of the donors were EBV-positive and one was EBV-negative. We succeeded in obtaining spontaneous lymphoblastoid cell lines (LCLs) from the blood of three of these donors, one of whom also yielded a cord-blood line established with his throat-wash EBV. Blood from a fourth donor did not yield an LCL, but his throat washing did have transforming activity when inoculated onto cord-blood leukocytes. We initially could establish spontaneous LCLs only from the recipient's blood. However, a throat-wash sample taken 11 weeks later did show transforming activity. The recipient was shown to have acquired the EBV infection from one of eight EBV-seropositive blood donors. Analysis of fragment length polymorphisms after polymerase chain reaction amplification of the EBV BamHI-K fragment was used to establish strain identity. Western blot analysis for existence of size polymorphisms in three classes of Epstein-Barr nuclear antigens (EBNA-1, EBNA-2, and EBNA-3) confirmed the DNA results. It is noteworthy that the blood donor responsible for transmitting his EBV strain to the recipient had experienced clinical infectious mononucleosis 15 months before donating blood. Our results may, thus, indicate a requirement for leukodepletion of blood destined for immunosuppressed EBV-negative patients. Finally, blood donors with a recent history of infectious mononucleosis should probably be identified so that their blood is not given to EBV-negative transplant patients.     

Demonstration of thermal dissipation of absorbed quanta during energy-dependent quenching of chlorophyll fluorescence in photosynthetic membranes

Generally biglycan, a small proteoglycan, has been thought to play a role as an extracellular matrix and/or a reservoir for other factors, such as TGF-beta and collagens. Recently, we have found that a soluble 100 kDa biglycan, produced from the rat thymic myoid cells and the brain glial cells, predominantly stimulates growth and differentiation of monocytic lineage cells from various lymphatic organs, including microglias. In the present study, we attempted to identify biological significance of the corresponding molecules in human, using five myasthenic thymuses (three with hyperplasia and two with thymoma) that had been surgically removed for therapeutic purpose. With immunohistochemistry, many biglycan positive cells were detected in the germinal center of the three hyperplastic thymuses, but not in the two thymuses associated with lymphocytic thymoma. Biglycan purified from the hyperplastic thymuses by an immunoaffinity column was found as a monomer with apparent molecular size of 95-100 kDa and self associated oligomers of greater than 201 kDa. The purified biglycan markedly stimulated the growth and differentiation of monocytic cells from haemopoietic stem cells of the rat bone marrow. These results suggest that particular cells, which produce haemopoietic biglycan, play significant roles in generation and maintenance of the hyperplastic changes associated with myasthenia gravis.     

Ozonation of Substituted Phenols in Aqueous Solutions over CuO-Al2O3 Catalyst

The oxidation of aqueous solutions of substituted phenols, chlorophenols (CPs) and nitrophenols (NPs), at 21±0.5°C and atmospheric pressure, by ozone over a copper–alumina catalyst system was studied. The total disappearance of phenol compounds for 15 to 30 minute reaction times was observed. The presence of the catalyst increased the reaction rate, diminished the ozone consumption and caused an advanced degradation of phenols. A number of six by-products was identified by gas chromatography/mass spectrometry technique (GC/MS), with or without silylation. Based on the experimental data several mechanistic suggestions for the catalytic ozonation are made.     

Increased density of somatostatin binding sites in respiratory nuclei of the brainstem in sudden infant death syndrome

We report the isolation and characterization of a Xenopus sequence, XNLRR-1, that is closely related to a gene for mouse neuronal leucine-rich repeat protein (NLRR-1). The cDNA clone is 4179 bp long and encodes a putative transmembrane glycoprotein of 718 amino acids, containing 12 leucine-rich repeats followed by one C2-type immunoglobulin-like domain and one fibronectin type-III repeat. XNLRR-1 is transcribed mainly in the developing eye area and the ventricular zone from diencephalon to hindbrain and slightly in spinal cord in Xenopus tadpoles. The similarity of the XNLRR-1 gene to other known cell adhesion molecules, together with the expression pattern, suggests that XNLRR-1 is involved in interactions at the neuronal cell surface.     

Induced tissue transformation and heart surgery

This article reports the research which led to the use of animal connective tissues in the construction of valvular prostheses and those which led to the use of electrically stimulated skeletal muscle for cardiac assistance. Although, very different at first glance these research have in common the transformation of biological tissues by physical or chemical means to adapt them to a new function. 1) Once implanted in a different species, animal connective tissues are destroyed by immunological reactions and collagen degeneration. These lesions can be prevented by both maskage of the antigenic groups and intermolecular crosslinking using Glutaraldehyde. The durability of such chemically treated tissues is based upon the stability of the biological material (concept of bioprosthesis) and not upon cell survival or tissue regeneration by host cell ingrowth (concept of graft). The valvular bioprostheses made from Glutaraldehyde treated pericardial tissue, keep after this treatment their advantage of biological tissues: they are not thrombogenic and do not require anticoagulation contrary to mechanical valves. Although they have a limited durability up to 10 to 15 years due to tissue calcification, they represent 40% of the valvular prostheses used in clinical practice today. 2) The clinical use of electrostimulated skeletal muscle has been delayed for a long time because of fatigue lesions. An original protocol of progressive sequential stimulation prior to the use of muscle prevents fatigue by the transformation of type I fatigable myosin into type II non fatigable myosin. The conditionned muscle i.e.: the latissimus dorsi, is then wrapped around the ventricles to either reinforce cardiac contraction or to replace a portion of the heart. In the past 10 years, this new operation of "dynamic cardiomyoplasty", has been performed in 84 patients suffering from the end stage heart failure in our institution and in over 500 patients throughout the world with significant functional improvement.     

Automated circular assume-guarantee reasoning

Model checking is a successful approach for verifying hardware and software systems. Despite its success, the technique suffers from the state explosion problem which arises due to the large state space of real-life systems. One solution to the state explosion problem is compositional verification, that aims to decompose the verification of a large system into the more manageable verification of its components. To account for dependencies between components, assume-guarantee reasoning defines rules that break-up the global verification of a system into local verification of individual components, using assumptions about the rest of the system. In recent years, compositional techniques have gained significant successes following a breakthrough in the ability to automate assume-guarantee reasoning. However, automation has been restricted to simple acyclic assume-guarantee rules. In this work, we focus on automating circular assume-guarantee reasoning in which the verification of individual components mutually depends on each other. We use a sound and complete circular assume-guarantee rule and we describe how to automatically build the assumptions needed for using the rule. Our algorithm accumulates joint constraints on the assumptions based on (spurious) counterexamples obtained from checking the premises of the rule, and uses a SAT solver to synthesize minimal assumptions that satisfy these constraints. To the best of our knowledge, our work is the first to fully automate circular assume-guarantee reasoning. We implemented our approach and compared it with established non-circular compositional methods that use learning or SAT-based techniques. The experiments show that the assumptions generated for the circular rule are generally smaller, and on the larger examples, we obtain a significant speedup.     

MeditAid: a wearable adaptive neurofeedback-based system for training mindfulness state

A recent interest in interaction design is towards the development of novel technologies emphasizing the value of mindfulness, monitoring, awareness, and self-regulation for both health and well-being. Whereas existing systems have focused mostly on relaxation and awareness of feelings, there has been little exploration on tools supporting the self-regulation of attention during mindfulness sitting meditation. This paper describes the design and initial evaluation of MeditAid, a wearable system integrating electroencephalography technology with an adaptive aural entrainment for real-time training of mindfulness state. The system identifies different meditative states and provides feedback to support users in deepening their meditation. We report on a study with 16 meditators about the perceived strengths and limitations of the MeditAid system. We demonstrate the benefits of binaural feedback in deepening meditative states, particularly for novice meditators.     

CO oxidation over structured carriers: A comparison of ceramic foams, honeycombs and beads

This work aims an experimental comparison of different packings on the basis of their pressure drop, mass and heat transfer properties. Ceramic foams, beads and a honeycomb monolith were used as carriers in the oxidation of carbon monoxide. The carriers were coated with active Pt/SnO₂. The CO oxidation rate was measured in the regime of external diffusion control at superficial gas velocities between 1 and 10 m/s. The volumetric rate coefficients and the pressure drop of packings with similar geometric surface area decreased in the sequence particles > foams > honeycomb. The magnitude of the temperature gradient along the catalytic bed decreased as going from honeycomb over larger particles to foams and small particles. Foams were superior over particle beds from the viewpoint of combined high mass transfer and low-pressure drop. The main advantage of foams as compared to honeycomb resided in the radial mixing enabling a better heat transfer to the reactor walls.