40 research outputs found
Myelin basic protein peptide 45–89 induces the release of nitric oxide from microglial cells.
Continuous (24 h) exposure of mixed oligodendrocyte/microglial cells to peptides
45–89 derived from citrullinated C8 isoforms of myelin basic protein (MBP) induces
cell death. In contrast, MBP-C8 at the same molecular concentration is not
toxic to oligodendrocyte/microglial cells as detected by the MTT test and trypan
blue exclusion method. The loss of oligodendrocyte/microglial cells resulted in the
release of cytochrome c from mitochondria, suggesting MBP 45–89-induced
apoptosis. On the other hand, peptides 45–89 stimulated the secretion of nitric
oxide from microglial cells only via induction of iNOS. The addition of peptide
45–89 to the microglial cells led to a decrease of the level of the inhibitory protein
IkB, indicating that activation of the transcription factor NF-kB is involved in these
processes. We propose that the immunodominant peptide 45–89 induces damage of
oligodendrocytes by activation of microglial cells and subsequent generation of
nitric oxide, and that this may be the first step in the initiation of autoimmunity
Investigation of the anisotropy of dissipation processes in single crystal of Yba2Cu3O7-d system
By means of contactless mechanical method of the measurement of energy losses
in superconductors, the anisotropy of dissipation processes has been studied in
single crystal high-temperature layered superconductors of Yba2Cu3O7-d system,
being in mixed state. The observed anisotropy of energy losses indicates the
possibility of the existence of the symmetry of order parameter of dx2-y2 type
in these single crystals.Comment: 4 pages, 3 figure
Autonomous robotic intracardiac catheter navigation using haptic vision
International audienceWhile all minimally invasive procedures involve navigating from a small incision in the skin to the site of the intervention, it has not been previously demonstrated how this can be done 10 autonomously. To show that autonomous navigation is possible, we investigated it in the hardest place to do it-inside the beating heart. We created a robotic catheter that can navigate through the blood-filled heart using wall-following algorithms inspired by positively thigmotactic animals. The catheter employs haptic vision, a hybrid sense using imaging for both touch-based surface identification and force sensing, to accomplish wall following inside the blood-filled heart. 15 Through in vivo animal experiments, we demonstrate that the performance of an autonomously-controlled robotic catheter rivals that of an experienced clinician. Autonomous navigation is a fundamental capability on which more sophisticated levels of autonomy can be built, e.g., to perform a procedure. Similar to the role of automation in fighter aircraft, such capabilities can free the clinician to focus on the most critical aspects of the procedure while providing precise and 20 repeatable tool motions independent of operator experience and fatigue
Temperature dependence investigation of dissipation processes in strongly anisotropic high-temperature superconductors of Bi-Pb-Sr-Ca-Cu-O system synthesized using solar energy
The investigation of temperature dependence of damping and period of
vibrations of HTSC superconductive cylinder of Bi-Pb-Sr-Ca-Cu-O system
suspended by a thin elastic thread and performing axial-torsional vibrations in
a magnetic field at temperatures above the critical one for the main phase
Tc=107 K were carried out. It was observed some "chaos" temperature region in
the temperature interval 107-138 K, where it is seen separate ripples of
dissipation and oscillation frequency. It is assumed that the "chaos" region
could point to a possibility of existence of other magnetic and more
high-temperature phases as single islands in a normal materials matrix.Comment: 10 pages, 0 figure
In Vivo Tissue Regeneration with Robotic Implants
Robots that reside inside the body to restore or enhance biological function have long been a staple
of science fiction. Creating such robotic implants poses challenges both in signaling between the
implant and the biological host as well as in implant design. To investigate these challenges, we
created a robotic implant to perform in vivo tissue regeneration via mechano-stimulation. The
robot is designed to induce lengthening of tubular organs, such as the esophagus and intestines, by
computer-controlled application of traction forces. Esophageal testing in swine demonstrates that
the applied forces can induce cell proliferation and lengthening of the organ without a reduction
in diameter, while the animal is awake, mobile and able to eat normally. Such robots can serve as
research tools for studying mechanotransduction-based signaling and can also be employed
clinically for conditions such as long-gap esophageal atresia and short bowel syndrome
Specific binding of cinnamycin (Ro 09-0198) to phosphatidylethanolamine : Comparison between micellar and membrane environments
Cinnamycin (Ro 09-0198) is a tetracyclic peptide antibiotic that binds specifically to phosphatidylethanolamine (PE). Formation of a complex with phosphatidylethanolamine follows a 1:1 stoichiometry. Using high-sensitivity isothermal titration calorimetry (ITC), we have measured the thermodynamic parameters of complex formation for two different PE environments, namely, PE dissolved either in octyl glucoside (OG) micelles or in a 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) bilayer membrane. We have compared diacyl-PE with lyso-PE and have varied the carbon chain length from 6 to 18. Binding requires both a PE headgroup and at least one fatty acyl chain. The optimum chain length for complex formation (n) is eight. Longer chains do not enhance the binding affinity; for shorter chains, the interaction is weakened. The cinnamycin-PE complex has a binding constant K(0) of approximately 10(7)-10(8) M(-1) in the POPC membrane and only approximately 10(6) M(-1) in the octyl glucoside micelle. The difference can be attributed to the nonspecific hydrophobic interaction of cinnamycin with the lipid membrane. Complex formation is enthalpy-driven in OG micelles, whereas enthalpy and entropy make equal contributions in bilayer membranes. However, for the optimum chain length (n) of eight, the binding reaction is also completely enthalpy-driven for the bilayer membrane
Specific binding of Ro 09-0198 (cinnamycin) to phosphatidylethanolamine : a thermodynamic analysis
Ro 09-0198 (cinnamycin) is a tetracyclic peptide antibiotic that is used to monitor the transbilayer movement of phosphatidylethanolamine (PE) in biological membranes during cell division and apoptosis. The molecule is one of the very rare examples where a small peptide binds specifically to a particular lipid. In model membranes and biological membranes containing phosphatidylethanolamine, Ro 09-0198 forms a 1:1 complex with this lipid. We have measured the thermodynamic parameters of complex formation with high sensitivity isothermal titration calorimetry and have investigated the structural consequences with deuterium and phosphorus solid-state NMR. Complex formation is characterized by a large binding constant, K0, of 10(7) to 10(8) M(-1), depending on the experimental conditions. The reaction enthalpy, DeltaHdegrees, varies between zero at 10 degrees C to strongly exothermic -10 kcal/mol at 50 degrees C. For large vesicles with a diameter of approximately 100 nm, DeltaHdegrees decreases linearly with temperature and the molar heat capacity of complex formation can be evaluated as = -245 cal/mol, indicating a hydrophobic binding mechanism. The free energy of binding is DeltaGdegrees = -10.5 kcal/mol and shows only little temperature dependence. The constancy of DeltaGdegrees together with the distinct temperature-dependence of DeltaHdegrees provide evidence for an entropy-enthalpy compensation mechanism: at 10 degrees C, complex formation is completely entropy-driven, at 50 degrees C it is enthalpy-driven. Varying the PE fatty acid chain-length between 6 and 18 carbon atoms produces similar binding constants and DeltaHdegrees values. Addition of Ro 09-0198 to PE containing bilayers eliminates the typical bilayer structure and produces 2H- and 31P-NMR spectra characteristic of slow isotropic tumbling. This reorganization of the lipid matrix is not limited to PE but also includes other lipids