Structures and functions of mitochondrial ABC transporters

A small number of physiologically important ATP-binding cassette (ABC) transporters are found in mitochondria. Most are half transporters of the B group forming homodimers and their topology suggests they function as exporters. The results of mutant studies point towards involvement in iron cofactor biosynthesis. In particular, ABC subfamily B member 7 (ABCB7) and its homologues in yeast and plants are required for iron-sulfur (Fe-S) cluster biosynthesis outside of the mitochondria, whereas ABCB10 is involved in haem biosynthesis. They also play a role in preventing oxidative stress. Mutations in ABCB6 and ABCB7 have been linked to human disease. Recent crystal structures of yeast Atm1 and human ABCB10 have been key to identifying substrate-binding sites and transport mechanisms. Combined with in vitro and in vivo studies, progress is being made to find the physiological substrates of the different mitochondrial ABC transporters

Virtual reality in managing Complex Regional Pain Syndrome (CRPS): a scoping review

BackgroundComplex Regional Pain Syndrome (CRPS) is a severe pain disorder that does not yet have a specific treatment. Patients with CRPS not only suffer from a wide range of symptoms that affect their quality of life but also present psychological affections to the way they see their body and specifically their affected limb. Virtual Reality (VR) modalities have become a targeted treatment for chronic pain and in the case of CRPS, may be a valuable approach to the mechanisms that affect these patients.ObjectivesUsing the PRISMA Scoping Review guidelines, we intend to uncover the key information from the studies available about VR modalities in the treatment of CRPS. We focus on the improvement of pain levels, body perception disturbances (BPD), and limb movement/daily function.ResultsOur search strategy resulted in 217 articles from PubMed. Twenty were assessed for eligibility and seven were included in the final qualitative synthesis. Of these seven articles, we included a clinical trial, three pilot studies, a blinded randomized controlled trial, a crossover double-blind trial, and a randomized controlled trial. These studies provide important subjective patient findings, along with some statistically significant results in the experiences of VR therapies modulating pain, BPD, and improving limb movement/daily function. However, not all the studies included statistical analysis, and there are contradicting data found from some patients that did not perceive any improvement from VR therapies.ConclusionsWe describe the results found in 7 articles that focus on the treatment of CRPS with VR modalities. Overall, the articles have various limitations, but the strategies related to immersive virtual reality, cardiac signaling, body switching and limb modulation have shown the most promising results for pain reduction and BPD improvement. These strategies reflect on pathophysiological mechanisms that are hypothesized to be affected in CRPS patients leading to the chronic pain and BPD that they experience. Not much evidence was found for improvement in limb movement and daily function. This review is a pathway for future studies on this topic and a more extensive data synthesis when more information is available

Cryo-EM structure of the complete and ligand-saturated insulin receptor ectodomain

Glucose homeostasis and growth essentially depend on the hormone insulin engaging its receptor. Despite biochemical and structural advances, a fundamental contradiction has persisted in the current understanding of insulin ligand-receptor interactions. While biochemistry predicts two distinct insulin binding sites, 1 and 2, recent structural analyses have resolved only site 1. Using a combined approach of cryo-EM and atomistic molecular dynamics simulation, we present the structure of the entire dimeric insulin receptor ectodomain saturated with four insulin molecules. Complementing the previously described insulin-site 1 interaction, we present the first view of insulin bound to the discrete insulin receptor site 2. Insulin binding stabilizes the receptor ectodomain in a T-shaped conformation wherein the membrane-proximal domains converge and contact each other. These findings expand the current models of insulin binding to its receptor and of its regulation. In summary, we provide the structural basis for a comprehensive description of ligand-receptor interactions that ultimately will inform new approaches to structure-based drug design.Peer reviewe

Monitoring Membrane Lipidome Turnover by Metabolic N-15 Labeling and Shotgun Ultra-High-Resolution Orbitrap Fourier Transform Mass Spectrometry

Lipidomes undergo permanent extensive remodeling, but how the turnover rate differs between lipid classes and molecular species is poorly understood. We employed metabolic N-15 labeling and shotgun ultra-high-resolution mass spectrometry (sUHR) to quantify the absolute (molar) abundance and determine the turnover rate of glycerophospholipids and sphingolipids by direct analysis of total lipid extracts. sUHR performed on a commercial Orbitrap Elite instrument at the mass resolution of 1.35 x 10 (6) (m/z 200) baseline resolved peaks of C-13 isotopes of unlabeled and monoisotopic peaks of N-15 labeled lipids (Delta m = 0.0063 Da). Therefore, the rate of metabolic N-15 labeling of individual lipid species could be determined without compromising the scope, accuracy, and dynamic range of full-lipidome quantitative shotgun profiling. As a proof of concept, we employed sUHR to determine the lipidome composition and fluxes of 62 nitrogen-containing membrane lipids in human hepatoma HepG2 cells

Monitoring Membrane Lipidome Turnover by Metabolic ¹⁵N Labeling and Shotgun Ultra-High-Resolution Orbitrap Fourier Transform Mass Spectrometry

Lipidomes undergo permanent extensive remodeling, but how the turnover rate differs between lipid classes and molecular species is poorly understood. We employed metabolic ¹⁵N labeling and shotgun ultra-high-resolution mass spectrometry (sUHR) to quantify the absolute (molar) abundance and determine the turnover rate of glycerophospholipids and sphingolipids by direct analysis of total lipid extracts. sUHR performed on a commercial Orbitrap Elite instrument at the mass resolution of 1.35 × 10⁶ (<i>m</i>/<i>z</i> 200) baseline resolved peaks of ¹³C isotopes of unlabeled and monoisotopic peaks of ¹⁵N labeled lipids (Δ<i>m</i> = 0.0063 Da). Therefore, the rate of metabolic ¹⁵N labeling of individual lipid species could be determined without compromising the scope, accuracy, and dynamic range of full-lipidome quantitative shotgun profiling. As a proof of concept, we employed sUHR to determine the lipidome composition and fluxes of 62 nitrogen-containing membrane lipids in human hepatoma HepG2 cells

Evaluation of effects of robot-assisted early mobilization on critically ill patients, on the mobilization behaviour and experience of the mobilizing professionals and the organizational processes in an intensive care unit -a clinical intervention study : study protocol

'''Background:''' Early mobilization positively influences the outcome of critically ill patients, yet in the clinical practice the implementation is sometimes challenging. In this study, an adaptive robotic assistance system will be used for early mobilization in intensive care units. The study aims to evaluate the experience of the mobilizing professionals, the effects on patient outcomes, and the general feasibility of implementing robotic assistance for mobilization in intensive care. '''Methods:''' The study is monocentric, prospective, interventional, and has multiple time points for data collection. To evaluate the feasibility of robotic-assisted early mobilization, the number of patients included, the number of performed VEM (very early mobilization) sessions, as well as the number and type of adverse events will be collected. The behavior and experience of mobilizing professionals will be evaluated using standardized observations (n>90) and episodic interviews (n>36) before implementation, shortly after, and in routine. Patient outcomes such as duration of mechanical ventilation, loss of muscle mass and physical activity will be measured and compared with a historical patient population. Approximately 30 patients will be included. '''Discussion:''' The study will provide information about patient outcomes, feasibility, and the experience of mobilizing professionals. It will show whether robotic systems can increase early mobilization frequency of critically ill patients. Within ICU structures, early mobilization as therapy could become more of a focus. Effects on the mobilizing professionals such as increased motivation, physical relief, or stress will be evaluated. In addition, this study will focus on whether current structures allow following the recommendation of mobilizing patients twice a day for at least 20 minutes. The aim of this study is to evaluate the implementation of a new standard of robotic-assisted early mobilization in the intensive care setting and whether it can be utilized permanently within the current framework. '''Trial registration:''' (clinicaltrials.org TRN: NCT05071248, Date: 2021/10/21) URL https://clinicaltrials.gov/ct2/show/NCT0507124

Relative lipid packing between domains correlates with BD-GM1 partitioning.

<p>a) GP, BD-GM1 (green) and the disordered marker FAST-DiI (red) imaged in various membrane preparations. BD-GM1 and FAST-DiI are imaged in the same vesicle; GP is shown form a different vesicle representative of the preparation. b) The quantification of BD-GM1 ordered phase partitioning versus ΔGP.</p

Various lipid mixtures yield a range of lipid packing states.

<p>(a) Natural PC mixtures (brain or liver PC extracts) yield liposomes with higher GP than synthetic DOPC bearing two unsaturated acyl chain. (b) Mixtures of cholesterol with natural SM (egg SM extract) and DPPC yield liposomes with lower order than cholesterol with pure SM 18:0. (c) Lipid packing of DOPC liposomes increases monotonically with increasing cholesterol. (d) Quantification of the effect of compositional variation on membrane order in one-phase liposomes.</p