Effects of fibinolysis on neurite growth from dorsal root ganglia cultured in two- and three-dimensional fibrin gels

The mechanism of neurite penetration of three-dimensional fibrin matrices was investigated by culturing embryonic chick dorsal root ganglia (DRGs) within fibrin gels, upon fibrin gels, and upon laminin. The length of neurites within three-dimensional matrices of fibrin was decreased in a concentration-dependent manner by agents that inhibited plasmin, e.g. aprotinin, or that inhibited plasminogen activation, e.g., epsilon-aminocaproic acid (EACA), or plasminogen antiserum. In contrast, such agents increased the length of neurites growing out from DRGs cultured upon two-dimensional substrates of fibrin and had no effect on the length of neurites growing out from DRGs cultured upon laminin. Visualization of neurites within three-dimensional fibrin matrices demonstrated that the distance between fibrin strands was much smaller than the diameter of neurites. All these data were consistent with the hypothesis that fibrinolysis localized to the region of the neurite tip is an important mechanism for neurite penetration of a physical barrier of fibrin strands arranged in a three-dimensional matrix.     

A peptide sequence from platelet factor 4 (CT-112) is effective in the treatment of type II collagen induced arthritis in mice

OBJECTIVE: Platelet factor 4 (PF-4) is a critical alpha chemokine in inflammation and injury responses, with multiple effects upon cellular activities. Discrete peptide sequences of the PF-4 molecule have been shown to retain biological activity. Our aim was to examine the influence of the PF-4 derived octapeptide (CT-112; TTSQVRPR) on type II collagen induced arthritis in mice, to determine if this peptide exhibited antiinflammatory properties. METHODS: DBA/1 mice were treated with CT-112 from either the time of immunization with type II collagen or from the initial onset of arthritis. RESULTS: CT-112 both prevented the development of arthritis in mice treated prophylactically and reduced progression of disease in animals treated therapeutically, and was active when delivered by either subcutaneous injection or oral gavage. No marked immunosuppressive effects were observed during CT-112 treatment, with only moderate decrease in antibody levels and mitogen responses. A significant reduction of the circulating levels of IL-1 was a consistent finding in mice treated therapeutically with CT-112. CONCLUSION: These data suggest PF-4 derived octapeptide exerts antiinflammatory effects of experimental arthritis in mice.     

Oxygen mass transfer calculations in large arteries

Parkinsonism is characterised by overactive glutamatergic transmission in the cortico-striatal and subthalamo-medial pallidal pathways. Local blockade of glutamatergic transmission in these pathways can alleviate parkinsonian symptoms. The effectiveness of the treatment, however, is often limited by the simultaneous appearance of unwanted side-effects. These side-effects, including ataxia and dissociative anaesthesia, are particularly problematic when N-methyl-D-aspartate (NMDA) antagonists are used. In an attempt to overcome these problems we have attempted to manipulate excitatory amino acid (EAA)-mediated neurotransmission indirectly by targeting the NMDA receptor associated modulatory sites. We review evidence which demonstrates that antagonists for both the NMDA associated glycine and polyamine sites can reverse parkinsonian symptoms when injected intra-cerebrally in both MPTP-treated and bilateral 6-OHDA lesioned marmosets without eliciting unwanted side-effects. We further review preliminary data which suggest that ifenprodil, a polyamine site antagonist, has striking anti-parkinsonian actions in the marmoset. Potential mechanisms of action underlying these effects are discussed in terms of NMDA receptor subtypes and the neuroanatomical locus of action. The anti-parkinsonian efficacy of intra-striatally administered EAA antagonists leads us to question the view of dopamine acting in the striatum as a simple neuromodulator.     

Analysis of tungsten and titanium migration during ESD contact burnout

A physical and chemical analysis of a machine model (MM) electrostatic discharge (ESD) failure in a silicon circuit was carried out. Focused ion beam (FIB) was used to make cross sections through the region of contact burnout. The resulting samples were analyzed using scanning electron microscopy (SEM) and two-dimensional (2-D) auger electron spectroscopic (AES) mapping. It is shown for the first time that both titanium (Ti) and tungsten (W) migrated throughout the melted silicon filament. Large pellets of the W plug were embedded in the bulk silicon but only on the cathode side of the junction. Mechanisms are discussed to explain these phenomena. These involve the melting of titanium disilicide (TiSi/sub 2/), dissolution of Ti and W in the molten silicon and the formation of W pellets through electromigration at temperatures below /spl sim/1800 K.     

Ab-initio primitive cell parameters from single convergent-beam electron diffraction patterns: a converse route to the identification of microcrystals with electrons.

A new method for the ab initio derivation of Buerger-reduced primitive cell parameters from coordinate measurements of spots on single convergent-beam electron diffraction (CBED) patterns is described, which does not involve trial-and-error. The pattern can be taken along any zone axis, and misorientations of the crystallite by as much as a few degrees are taken into account without loss of accuracy. This derivation of cell parameters by least-squares analysis of the measurements has been automated in a program called NRCBED. Present accuracy is about 1% on lengths and 2 degrees on angles, but could be significantly improved by modelling projector lens aberrations, or by using a microscope without a projector lens. With present technology, it is possible to obtain a CBED pattern and a semi-quantitative energy-dispersive X-ray (EDX) analysis simultaneously from a single microcrystal a few hundred Angstr?ms across. It becomes therefore possible to identify the material of the crystal on a single CBED pattern: a cell parameter database for known compounds is searched with the primitive cell parameters obtained in the above way, and with a mask describing the EDX results qualitatively. Feasibility is demonstrated on a crystallite of CeO2 500 Angstr?ms across. With this new approach, trial-and-error should disappear from the solution of other long-standing problems: interpretation of X-ray powder patterns for new compounds in the presence of impurity lines, or in the case of multiple phases should become straight-forward.     

Highly integrated direct conversion receiver for GSM/GPRS/EDGE with on-chip 84-dB dynamic range continuous-time /spl Sigma//spl Delta/ ADC

This paper describes a highly digitized direct conversion receiver of a single-chip quadruple-band RF transceiver that meets GSM/GPRS and EDGE requirements. The chip uses an advanced 0.25-/spl mu/m BiCMOS technology. The I and Q on-chip fifth-order single-bit continuous-time sigma-delta (/spl Sigma//spl Delta/) ADC has 84-dB dynamic range over a total bandwidth of /spl plusmn/135 kHz for an active area of 0.4 mm/sup 2/. Hence, most of the channel filtering is realized in a CMOS IC where digital processing is achieved at a lower cost. The systematic analysis of dc offset at each stage of the design enables to perform the dc offset cancellation loop in the digital domain as well. The receiver operates at 2.7 V with a current consumption of 75 mA. A first-order substrate coupling analysis enables to optimize the floor plan strategy. As a result, the receiver has an area of 1.8 mm/sup 2/.     

A distributed approach for access and visibility task with a manikin and a robot in a virtual reality environment

This paper presents a new method, based on a multi-agent system and on a digital mock-up technology, to assess an efficient path planner for a manikin or a robot for an access and visibility task taking into account ergonomic constraints or joint and mechanical limits. In order to solve this problem, the human operator is integrated in the process optimization to contribute to a global perception of the environment. This operator cooperates, in real time, with several automatic local elementary agents. The result of this work validates solutions through the digital mock-up; it can be applied to simulate maintainability and mountability tasks.     

In situ regeneration of the Ni-based catalytic reformer of a 5 kW PEMFC system

The paper reports the results of on-site regeneration catalytic bed of the natural gas reformer in a 5 kW PEM fuel cell system. The Ni catalyst previously poisoned by sulphur from the available natural gas, could be re-activated by injection of pure water steam, following the method developed for industrial reformers using the same metal catalyst: this method was shown to be perfectly efficient, provided no natural gas was fed during the operation. Results of the tests conducted are presented and discussed in relation to published data on S-sorption on Ni surfaces.