Tractography dissection variability: What happens when 42 groups dissect 14 white matter bundles on the same dataset?

White matter bundle segmentation using diffusion MRI fiber tractography has become the method of choice to identify white matter fiber pathways in vivo in human brains. However, like other analyses of complex data, there is considerable variability in segmentation protocols and techniques. This can result in different reconstructions of the same intended white matter pathways, which directly affects tractography results, quantification, and interpretation. In this study, we aim to evaluate and quantify the variability that arises from different protocols for bundle segmentation. Through an open call to users of fiber tractography, including anatomists, clinicians, and algorithm developers, 42 independent teams were given processed sets of human whole-brain streamlines and asked to segment 14 white matter fascicles on six subjects. In total, we received 57 different bundle segmentation protocols, which enabled detailed volume-based and streamline-based analyses of agreement and disagreement among protocols for each fiber pathway. Results show that even when given the exact same sets of underlying streamlines, the variability across protocols for bundle segmentation is greater than all other sources of variability in the virtual dissection process, including variability within protocols and variability across subjects. In order to foster the use of tractography bundle dissection in routine clinical settings, and as a fundamental analytical tool, future endeavors must aim to resolve and reduce this heterogeneity. Although external validation is needed to verify the anatomical accuracy of bundle dissections, reducing heterogeneity is a step towards reproducible research and may be achieved through the use of standard nomenclature and definitions of white matter bundles and well-chosen constraints and decisions in the dissection process

Structural basis of TIR-domain-assembly formation in MAL- and MyD88-dependent TLR4 signaling

Toll-like receptor (TLR) signaling is a key innate immunity response to pathogens. Recruitment of signaling adapters such as MAL (TIRAP) and MyD88 to the TLRs requires Toll/interleukin-1 receptor (TIR)-domain interactions, which remain structurally elusive. Here we show that MAL TIR domains spontaneously and reversibly form filaments in vitro. They also form cofilaments with TLR4 TIR domains and induce formation of MyD88 assemblies. A 7-Å-resolution cryo-EM structure reveals a stable MAL protofilament consisting of two parallel strands of TIR-domain subunits in a BB-loop-mediated head-to-tail arrangement. Interface residues that are important for the interaction are conserved among different TIR domains. Although large filaments of TLR4, MAL or MyD88 are unlikely to form during cellular signaling, structure-guided mutagenesis, combined with in vivo interaction assays, demonstrated that the MAL interactions defined within the filament represent a template for a conserved mode of TIR-domain interaction involved in both TLR and interleukin-1 receptor signaling

Peripheral venipuncture in elderly patients: is near-infrared light technology an option to avoid vein depletion?

Background: Peripheral venipuncture is the minimal invasive procedure most commonly performed in acute settings. However, several publications report that health professionals perform multiple puncture attempts until a successful catheterization or blood draw is achieved. Among the patients most affected by this reality are the elderly patients, who often display a number of factors that increase difficulty. In recent years, several recent technological aids, such as the Near-Infrared Light, have emerged in the medical devices market as potential facilitators of vein selection and puncture. However, while Near-Infrared Light devices are widely studied in pediatric settings, there are no known reviews of its use and applicability with elderly patients. Methods: A scoping review of the literature was conducted following the Joanna Briggs Institute method. Study relevance, data extraction, and synthesis were performed by two independent reviewers. Results: Three studies were included in this review. The use of NIR technology may improve the number of peripheral veins located in elderly patients, as well as reduce hematoma development and patient anxiety before, during and after the procedure. Moreover, one study briefly explored health professionals’ usability and technology acceptance related outcomes. Conclusions: While peripheral venipuncture of elderly patients assisted by NIR devices is still an understudied area, the studies found indicated results favorable to its clinical application. However, such results should be carefully analyzed, since potential bias and lack of larger study samples may prevent the generalization of the results.info:eu-repo/semantics/publishedVersio