A murine model of Charcot-Marie-Tooth disease 4F reveals a role for the C-terminus of periaxin in the formation and stabilization of Cajal bands

Charcot-Marie-Tooth (CMT) disease comprises up to 80 monogenic inherited neuropathies of the peripheral nervous system (PNS) that collectively result in demyelination and axon degeneration. The majority of CMT disease is primarily either dysmyelinating or demyelinating in which mutations affect the ability of Schwann cells to either assemble or stabilize peripheral nerve myelin. CMT4F is a recessive demyelinating form of the disease caused by mutations in the Periaxin (PRX) gene. Periaxin (Prx) interacts with Dystrophin Related Protein 2 (Drp2) in an adhesion complex with the laminin receptor Dystroglycan (Dag). In mice the Prx/Drp2/Dag complex assembles adhesive domains at the interface between the abaxonal surface of the myelin sheath and the cytoplasmic surface of the Schwann cell plasma membrane. Assembly of these appositions causes the formation of cytoplasmic channels called Cajal bands beneath the surface of the Schwann cell plasma membrane. Loss of either Periaxin or Drp2 disrupts the appositions and causes CMT in both mouse and man. In a mouse model of CMT4F, complete loss of Periaxin first prevents normal Schwann cell elongation resulting in abnormally short internodal distances which can reduce nerve conduction velocity, and subsequently precipitates demyelination. Distinct functional domains responsible for Periaxin homodimerization and interaction with Drp2 to form the Prx/Drp2/Dag complex have been identified at the N-terminus of Periaxin. However, CMT4F can also be caused by a mutation that results in the truncation of Periaxin at the extreme C-terminus with the loss of 391 amino acids. By modelling this in mice, we show that loss of the C-terminus of Periaxin results in a surprising reduction in Drp2. This would be predicted to cause the observed instability of both appositions and myelin, and contribute significantly to the clinical phenotype in CMT4F

Impact of COVID-19 crisis on medical care of patients with metastasized uro-oncologic disease under systemic cancer therapy: a multicenter study in German university hospitals

Purpose!#!To date, over 4.2 million Germans and over 235 million people worldwide have been infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Uro-oncology (UO) patients are particularly vulnerable but in urgent need of life-saving systemic treatments. Our multicentric study examined the impact of the COVID-19 crisis on the medical care of UO patients in German university hospitals receiving ongoing systemic anti-cancer treatment and to detect the delay of medical care, defined as deferred medical treatment or deviation of the pre-defined follow-up assessment.!##!Methods!#!Data of 162 UO patients with metastatic disease undergoing systemic cancer treatment at five university hospitals in Germany were included in our analyses. The focus of interest was any delay or change in treatment between February 2020 and May 2020 (first wave of the COVID-19 crisis in Germany). Statistical analysis of contingency tables were performed using Pearson's chi-squared and Fisher's exact tests, respectively. Effect size was determined using Cramér's V (V).!##!Results!#!Twenty-four of the 162 patients (14.8%) experienced a delay in systemic treatment of more than 2 weeks. Most of these received immuno-oncologic (IO) treatments (13/24, 54.2%, p = 0.746). Blood tests were delayed or canceled significantly more often in IO patients but with a small effect size (21.1%, p = 0.042, V = 0.230). Treatment of patients with renal cell carcinoma (12/73, 16.4%) and urothelial carcinoma (7/32, 21.9%) was affected the most.!##!Conclusions!#!Our data show that the COVID-19 pandemic impacted the medical care of UO patients, but deferment remained modest. There was a tendency towards delays in IO and ADT treatments in particular

Exploring the interactome : microfluidic isolation of proteins and interacting partners for quantitative analysis by electron microscopy

Multimolecular protein complexes are important for many cellular processes. However, the stochastic nature of the cellular interactome makes the experimental detection of complex protein assemblies difficult and quantitative analysis at the single molecule level essential. Here, we present a fast and simple microfluidic method for (i) the quantitative isolation of endogenous levels of untagged protein complexes from minute volumes of cell lysates under close to physiological conditions and (ii) the labeling of specific components constituting these complexes. The method presented uses specific antibodies that are conjugated via a photocleavable linker to magnetic beads that are trapped in microcapillaries to immobilize the target proteins. Proteins are released by photocleavage, eluted, and subsequently analyzed by quantitative transmission electron microscopy at the single molecule level. Additionally, before photocleavage, immunogold can be employed to label proteins that interact with the primary target protein. Thus, the presented method provides a new way to study the interactome and, in combination with single molecule transmission electron microscopy, to structurally characterize the large, dynamic, heterogeneous multimolecular protein complexes formed

Diagnostic kinésithérapique : concepts fondateurs et modèles

Evolution de l'acte et de la profession de kinésithérapeute. Classification : la CIF. Le diagnostic : la liste de l'APTA