Ultrastructural Analysis of Neuroimplant-Parenchyma Interfaces Uncover Remarkable Neuroregeneration Along-With Barriers That Limit the Implant Electrophysiological Functions

Despite increasing use of in vivo multielectrode array (MEA) implants for basic research and medical applications, the critical structural interfaces formed between the implants and the brain parenchyma, remain elusive. Prevailing view assumes that formation of multicellular inflammatory encapsulating-scar around the implants [the foreign body response (FBR)] degrades the implant electrophysiological functions. Using gold mushroom shaped microelectrodes (gMμEs) based perforated polyimide MEA platforms (PPMPs) that in contrast to standard probes can be thin sectioned along with the interfacing parenchyma; we examined here for the first time the interfaces formed between brains parenchyma and implanted 3D vertical microelectrode platforms at the ultrastructural level. Our study demonstrates remarkable regenerative processes including neuritogenesis, axon myelination, synapse formation and capillaries regrowth in contact and around the implant. In parallel, we document that individual microglia adhere tightly and engulf the gMμEs. Modeling of the formed microglia-electrode junctions suggest that this configuration suffice to account for the low and deteriorating recording qualities of in vivo MEA implants. These observations help define the anticipated hurdles to adapting the advantageous 3D in vitro vertical-electrode technologies to in vivo settings, and suggest that improving the recording qualities and durability of planar or 3D in vivo electrode implants will require developing approaches to eliminate the insulating microglia junctions.

Ultrastructural analysis of neuroimplant-parenchyma interfaces uncover remarkable neuroregeneration along-with barriers that limit the implant electrophysiological functions

Despite increasing use of in-vivo multielectrode array (MEA) implants for basic research and medical applications, the critical structural interfaces formed between the implants and the brain parenchyma, remain elusive. Prevailing view assumes that formation of multicellular inflammatory encapsulating-scar around the implants (the foreign body response) degrades the implant electrophysiological functions. Using gold mushroom shaped microelectrodes (gMμEs) based perforated polyimide MEA platforms (PPMPs) that in contrast to standard probes can be thin sectioned along with the interfacing parenchyma; we examined here for the first time the interfaces formed between brains parenchyma and implanted 3D vertical microelectrode platforms at the ultrastructural level. Our study demonstrates remarkable regenerative processes including neuritogenesis, axon myelination, synapse formation and capillaries regrowth in contact and around the implant. In parallel, we document that individual microglia adhere tightly and engulf the gMμEs. Modeling of the formed microglia-electrode junctions suggest that this configuration suffice to account for the low and deteriorating recording qualities of in vivo MEA implants. These observations help define the anticipated hurdles to adapting the advantageous 3D in-vitro vertical-electrode technologies to in-vivo settings, and suggest that improving the recording qualities and durability of planar or 3D in-vivo electrode implants will require developing approaches to eliminate the insulating microglia junctions.

Computational Investigation Of Structural Interfaces Of Protein Complexes With Short Linear Motifs

Protein complexes with short linear motifs (SLiMs) are known to play important regulatory functions in eukaryotes. In this investigation, I have studied the structures deposited in PDB with SLiMs. The structures Were grouped into three broad categories of protein-protein, protein-peptide and the rest as others. Protein-peptide complexes Were found to be most highly represented. The interfaces Were evaluated for geometric features and conformational variables. It was observed that protein-protein and protein-peptide complexes show characteristic differences in residue pairings, which Were quantified by evaluating normalized contact residue pairing frequencies. Interface residues adopt characteristic canonical residue conformations in the Ramachandran space, with a pronounced preference for positive ϕ conformations. It was observed that phosphorylated residues have an unusual propensity to adopt the unusual positive ϕ conformations at the interface.

One-way wave-equation migration of multiples based on stereographic imaging condition

Multiples are usually regarded as noise in conventional seismic data processing. However, multiples are also real reflections from structural interfaces in the subsurface. Compared with primaries, multiples usually provide more balanced illumination and contain more structural information because of the smaller reflection angles and longer wavepaths. Instead of multiple suppression, multiple imaging has attracted increasingly more attention in recent years. The most commonly used migration method for multiples is performed by replacing the source wavelet with recorded data and using separated multiples as the receiver record. Then, the image of the multiples is obtained by the application of the crosscorrelation imaging condition, which is widely used in conventional migration. However, during the imaging procedure, events are matched based on their propagation times only. Crosscorrelation of unrelated events leads to heavy crosstalk, and image artifacts are introduced in the image of multiples. To overcome this shortcoming, we have introduced the stereographic imaging condition for the one-way wave-equation migration of multiples. By adding a local-slope constraint (the local slope of the extrapolated wavefields at every position and time), the stereographic imaging condition takes the local spatial coherence of the extrapolated wavefields into account. Events can be matched based not only on the propagating times but also the local slopes. Therefore, crosstalk artifacts caused by the interference of unrelated events can be efficiently suppressed. Furthermore, to improve the computational accuracy and efficiency of our approach, plane-wave destructors are introduced to estimate the reflector slopes. In this way, the need for excessive loops over the local slopes in the [Formula: see text]-[Formula: see text] domain during application of the stereographic imaging condition can be avoided by selecting the local slopes in a proper range. Better migration results of multiples are obtained in numerical tests, which verify the feasibility and effectiveness of our approach.

Policy analysis by academics

Through their policy relevant research outputs and integration in policy networks, Belgian academics ‘speak truth to power’ (Wildavsky 1979) or ‘make sense together’ (Hoppe 1999) in political and public debates about policy problems and options. At the turn of the millennium, the federal and regional governments have moved to institutionalizing policy relevant research in what are called interuniversity research pillars, and middle to long term research programmes, thematically organised along the priorities decided by the respective governments. Next to these structural interfaces, there are other access points for academics to bring their expertise to policy-making. Sectoral academic experts maintain multiple relationships with knowledge brokers. They are welcome guests in opinion sections of the written and spoken media and hold positions in the strategic advisory bodies of different governments. Several of them are also active in think tanks, or act themselves as consultants in commercial university spin-offs. This chapter analyses the structural and individual access of academics to policy-making in Belgium. The empirical material is based upon documents analysis and budget information, on a study of knowledge utilisation in labour market and education policies in Belgium, and on a recent survey on the impact of social science research on Flemish policy-makers.