Ligand binding to a G protein–coupled receptor captured in a mass spectrometer

Copyright © 2017 The Authors, some rights reserved. G protein (heterotrimeric guanine nucleotide–binding protein)–coupled receptors belong to the largest family of membrane-embedded cell surface proteins and are involved in a diverse array of physiological processes. Despite progress in the mass spectrometry of membrane protein complexes, G protein–coupled receptors have remained intractable because of their low yield and instability after extraction from cell membranes. We established conditions in the mass spectrometer that preserve noncovalent ligand binding to the human purinergic receptor P2Y1. Results established differing affinities for nucleotides and the drug MRS2500 and link antagonist binding with the absence of receptor phosphorylation. Overall, therefore, our results are consistent with drug binding, preventing the conformational changes that facilitate downstream signaling. More generally, we highlight opportunities for mass spectrometry to probe effects of ligand binding on G protein–coupled receptors

Knowledge, attitudes and practices (KAP) relating to avian influenza in urban and rural areas of China

<p>Abstract</p> <p>Background</p> <p>Studies have revealed that visiting poultry markets and direct contact with sick or dead poultry are significant risk factors for H5N1 infection, the practices of which could possibly be influenced by people's knowledge, attitudes and practices (KAPs) associated with avian influenza (AI). To determine the KAPs associated with AI among the Chinese general population, a cross-sectional survey was conducted in China.</p> <p>Methods</p> <p>We used standardized, structured questionnaires distributed in both an urban area (Shenzhen, Guangdong Province; n = 1,826) and a rural area (Xiuning, Anhui Province; n = 2,572) using the probability proportional to size (PPS) sampling technique.</p> <p>Results</p> <p>Approximately three-quarters of participants in both groups requested more information about AI. The preferred source of information for both groups was television. Almost three-quarters of all participants were aware of AI as an infectious disease; the urban group was more aware that it could be transmitted through poultry, that it could be prevented, and was more familiar with the relationship between AI and human infection. The villagers in Xiuning were more concerned than Shenzhen residents about human AI viral infection. Regarding preventative measures, a higher percentage of the urban group used soap for hand washing whereas the rural group preferred water only. Almost half of the participants in both groups had continued to eat poultry after being informed about the disease.</p> <p>Conclusions</p> <p>Our study shows a high degree of awareness of human AI in both urban and rural populations, and could provide scientific support to assist the Chinese government in developing strategies and health-education campaigns to prevent AI infection among the general population.</p

Effectiveness of smartphone-based community case management on the urgent referral, reconsultation, and hospitalization of children aged under 5 years in Malawi: cluster-randomized, stepped-wedge trial

Background: Integrated community case management (CCM) has led to reductions in child mortality in Malawi from illnesses such as malaria, pneumonia and diarrhoea. However, adherence to CCM guidelines is often poor, potentially leading to inappropriate clinical decisions and poor outcomes. We determined the impact of an electronic version of a smartphone-based CCM (eCCM) application on referral, re-consultation and hospitalization rates of children presenting to village clinics in Malawi. Methods: A stepped-wedge cluster-randomized trial compared paper-based CCM (control) with and without use of an eCCM app on smartphones from November 2016 to February 2017. A total of 102 village clinics from two districts in Northern Malawi were assigned to one of six clusters which were randomized to the sequencing of crossover from the control to the intervention phases, as well as the duration of exposure in each phase. Children ≥2 months to 0.05). Conclusions: Addition of eCCM decision support using smartphones led to a greater proportion of children being referred to higher-level facilities, with no apparent increase in hospital admissions or repeat consultations in village clinics. Our findings provide support for the implementation of eCCM tools in Malawi and other Low and Middle Income Countries (LMIC), with a need for ongoing assessment of effectiveness and integration with national digital health strategies. Trial registration: ClinicalTrials.gov; NCT02763345. Registered 3 May 201

Identifying key membrane protein lipid interactions using mass spectrometry

With the recent success in determining membrane protein structures, further detailed understanding of the identity and function of the bound lipidome is essential. Using an approach that combines high-energy native mass spectrometry (HE-nMS) and solution-phase lipid profiling, this protocol can be used to determine the identity of the endogenous lipids that directly interact with a protein. Furthermore, this method can identify systems in which such lipid binding has a major role in regulating the oligomeric assembly of membrane proteins. The protocol begins with recording of the native mass spectrum of the protein of interest, under successive delipidation conditions, to determine whether delipidation leads to disruption of the oligomeric state. Subsequently, we propose using a bipronged strategy: first, an HE-nMS platform is used that allows dissociation of the detergent micelle at the front end of the instrument. This allows for isolation of the protein-lipid complex at the quadrupole and successive fragmentation at the collision cell, which leads to identification of the bound lipid masses. Next, simultaneous coupling of this with in-solution LC-MS/MS-based identification of extracted lipids reveals the complete identity of the interacting lipidome that copurifies with the proteins. Assimilation of the results of these two sets of experiments divulges the complete identity of the set of lipids that directly interact with the membrane protein of interest, and can further delineate its role in maintaining the oligomeric state of the protein. The entire procedure takes 2 d to complete

Ligand binding to a G protein-coupled receptor captured in a mass spectrometer.

G protein (heterotrimeric guanine nucleotide-binding protein)-coupled receptors belong to the largest family of membrane-embedded cell surface proteins and are involved in a diverse array of physiological processes. Despite progress in the mass spectrometry of membrane protein complexes, G protein-coupled receptors have remained intractable because of their low yield and instability after extraction from cell membranes. We established conditions in the mass spectrometer that preserve noncovalent ligand binding to the human purinergic receptor P2Y1. Results established differing affinities for nucleotides and the drug MRS2500 and link antagonist binding with the absence of receptor phosphorylation. Overall, therefore, our results are consistent with drug binding, preventing the conformational changes that facilitate downstream signaling. More generally, we highlight opportunities for mass spectrometry to probe effects of ligand binding on G protein-coupled receptors

Ligand binding to a G protein-coupled receptor captured in a mass spectrometer.

G protein (heterotrimeric guanine nucleotide-binding protein)-coupled receptors belong to the largest family of membrane-embedded cell surface proteins and are involved in a diverse array of physiological processes. Despite progress in the mass spectrometry of membrane protein complexes, G protein-coupled receptors have remained intractable because of their low yield and instability after extraction from cell membranes. We established conditions in the mass spectrometer that preserve noncovalent ligand binding to the human purinergic receptor P2Y1. Results established differing affinities for nucleotides and the drug MRS2500 and link antagonist binding with the absence of receptor phosphorylation. Overall, therefore, our results are consistent with drug binding, preventing the conformational changes that facilitate downstream signaling. More generally, we highlight opportunities for mass spectrometry to probe effects of ligand binding on G protein-coupled receptors

A static position-adjustment method for the motion prediction of the flexible floating collision-prevention system

The Flexible Floating Collision-Prevention System (FFCPS), used to prevent collision between uncontrolled ships and non-navigational bridges, comprises cable chains, floating structures and mooring system. Its main working principle is to use the sliding of the mooring systems in the role of energy dissipation. It can convert the kinetic energy of the ship into internal energy, and thus achieve the effect of avoiding a ship collision. The force relationships between various components of the system and ensuing simplified numerical models are firstly established in order to study the movement of the FFCPS. Subsequently, using suitable assumptions, the method of position adjustment to approach equilibrium condition is introduced. This method is based on the concept of statically determinate equilibrium in each step. The feasibility of the method proposed in this paper is verified by comparing the calculated results with model test measurements and published reference predictions. From these comparisons it is concluded that this method can be used in the preliminary design stage of the FFCPS