3,4-Bis(hydroxymethyl)hexane-1,6-diol-based Maltosides (HDMs) for Membrane-Protein Study: Importance of Detergent Rigidity-Flexibility Balance in Protein Stability.

Detergents have been major contributors to membrane-protein structural study for decades. However, membrane proteins solubilized in conventional detergents tend to aggregate or denature over time. Stability of large eukaryotic membrane proteins with complex structures tends to be particularly poor, necessitating development of novel detergents with improved properties. Here, we prepared a novel class of detergents, designated 3,4-bis(hydroxymethyl)hexane-1,6-diol-based maltosides (HDMs). When tested on three membrane proteins, including two G-protein-coupled receptors (GPCRs), the new detergents displayed significantly better behaviors compared with DDM. Moreover, the HDMs were superior or comparable to LMNG, an amphiphile widely used for GPCR structural study. An optimal balance of detergent rigidity vs. flexibility of the HDMs is likely responsible for their favorable behaviors toward membrane-protein stability. Thus, the current study not only introduces the HDMs, with significant potential for membrane-protein structural study, but also suggests a useful guideline for designing novel detergents for membrane-protein research.

[Corrosion damage in oesophagus after digesting a button battery].

Button batteries are present in most households, i.e. in toys, hearing aids and remote controls. Due to technical progression button batteries have become increasingly powerful and have simultaneously increased the risk of severe complications when ingested. In this case report, an X-ray of a ten-month-old baby revealed a button battery trapped in the upper part of oesophagus. The battery was removed within two hours from the time of swallowing, but the battery had inflicted severe damage of the oesophageal mouth. The patient was hospitalized for three days, controlled for three months and showed no signs of swallowing difficulties or other sequelae.

Foldable Detergents for Membrane Protein Study: Importance of Detergent Core Flexibility in Protein Stabilization.

Membrane proteins are of biological and pharmaceutical significance. However, their structural study is extremely challenging mainly due to the fact that only a small number of chemical tools are suitable for stabilizing membrane proteins in solution. Detergents are widely used in membrane protein study, but conventional detergents are generally poor at stabilizing challenging membrane proteins such as G protein-coupled receptors and protein complexes. In the current study, we prepared tandem triazine-based maltosides (TZMs) with two amphiphilic triazine units connected by different diamine linkers, hydrazine (TZM-Hs) and 1,2-ethylenediamine (TZM-Es). These TZMs were consistently superior to a gold standard detergent (DDM) in terms of stabilizing a few membrane proteins. In addition, the TZM-Es containing a long linker showed more general protein stabilization efficacy with multiple membrane proteins than the TZM-Hs containing a short linker. This result indicates that introduction of the flexible1,2-ethylenediamine linker between two rigid triazine rings enables the TZM-Es to fold into favourable conformations in order to promote membrane protein stability. The novel concept of detergent foldability introduced in the current study has potential in rational detergent design and membrane protein applications.

Limits and potential implementation of the present pN classification for oral squamous cell carcinoma.

PURPOSE OF REVIEW: The purpose of this review is to highlight the most important changes in the eighth TNM classification system for oral squamous cell carcinomas compared with the seventh edition with focus on lymph node staging (pN). Nodal involvement is crucial when addressing prediction of survival, and staging must mirror the disease extension. pN classification will be evaluated with respect to lymph node yield (LNY), lymph node density (LND), and a recently proposed classification: pN-N+ reflecting positive regional lymph nodes (metastatic burden) and extra nodal extension. RECENT FINDINGS: TNM8 was introduced in 2018, and the most noteworthy changes were depth of invasion (DOI) and extranodal extension (ENE). Recent studies indicate, that TNM8-related pN is not superior to TNM7 with respect to predicting survival. LNY and LND are biased with ecological interference fallacy, and currently not recommended in future iterations of TNM. In contrast, the pN-N+ classification has demonstrated improved survival prediction compared with TNM8. SUMMARY: The recent findings support the inclusion of pN-N+, that is, metastatic burden and extranodal extension in future iterations of TNM.

A Randomized, Single-Blinded Clinical Trial Evaluating the Effect of Extracorporeal Shockwave Treatment (ESWT) as Add-On Therapy to Vacuum Erectile Device on Peyronie's Disease.

PURPOSE: The aim of this study was to investigate whether ESWT with a higher energy as an add-on therapy to vacuum-pump followed by manipulation exercises could reduce the penile curvature, pain and improve IIEF-5 score. MATERIALS AND METHODS: Men aged >18 and <80 years and diagnosed with PD in stable phase with no history of penile surgery or previous ESWT treatment were eligible to participate. They were randomised to either active ESWT (n = 16) or sham ESWT (n = 16). Both groups were treated once a week for five weeks. Each treatment session consisted of 2000 shockwaves at 0.5mJ/mm2. All patients in both groups used a vacuum pump followed by manipulation exercises. RESULTS: Thirty men completed the study protocol. Mean age in the treatment group was 61.7 (SD 8.3) and 63 (SD 7.35) in the control group. After six months, mean change in penile curvature was -12.8 (SD 13) degrees in the treatment group and -6.6 (SD 8.9) in the control group (p = 0.204). Mean IIEF-5 score decreased by 0.17 (SD 3) in the treatment group and 3.06 (SD 5.5) in the control group (p = 0.086) at six-month follow-up. Pain was assessed using both VAS and PDQ and demonstrated no difference between the groups after six months (p = 0.648). CONCLUSION: In the treatment group, we observed a greater but non-significant change in penile curvature and no adverse effects.

Maltose-bis(hydroxymethyl)phenol (MBPs) and Maltose-tris(hydroxymethyl)phenol (MTPs) Amphiphiles for Membrane Protein Stability.

Membrane protein structures provide a fundamental understanding of their molecular actions and are of importance for drug development. Detergents are widely used to solubilize, stabilize, and crystallize membrane proteins, but membrane proteins solubilized in conventional detergents are prone to denaturation and aggregation. Thus, developing novel detergents with enhanced efficacy for protein stabilization remains important. We report herein the design and synthesis of a class of phenol-derived maltoside detergents. Using two different linkers, we prepared two sets of new detergents, designated maltose-bis(hydroxymethyl)phenol (MBPs) and maltose-tris(hydroxymethyl)phenol (MTPs). The evaluation of these detergents with three transporters and two G-protein coupled receptors allowed us to identify a couple of new detergents (MBP-C9 and MTP-C12) that consistently conferred enhanced stability to all tested proteins compared to a gold standard detergent (DDM). Furthermore, the data analysis based on the detergent structures provides key detergent features responsible for membrane protein stabilization that together will facilitate the future design of novel detergents.

Real-time predictions of seabird distribution improve oil spill risk assessments.

Current knowledge of the distribution of sensitive seabirds is inadequate to safeguard seabird populations from impacts of oil spills in the Arctic. This gap is mainly driven by the fact that statistical models applied to survey data are coarse-scale and static with limited documentation of the distributional dynamics and patchiness of seabirds relevant to risk assessments related to oil spills. This paper describes a dynamic modelling framework solution for prediction of fine-scale densities and movements of seabirds in close-to-real time using fully integrated 3-D hydrodynamic models, dynamic habitat suitability models and agent-based models. The modelling framework has been developed and validated for the swimming migration of Brünnich's Guillemot Uria lomvia in the Barents Sea. The results document that the distributional dynamics of Brünnich's Guillemot and other seabird species to a large degree can be simulated with in-situ state variables and patterns reflecting the physical meteorology and oceanography and habitat suitability.

Erectile Dysfunction A Prospective Randomized Placebo-Controlled Study Evaluating the Effect of Low-Intensity Extracorporeal Shockwave Therapy (LI-ESWT) in Men With Erectile Dysfunction Following Radical Prostatectomy.

INTRODUCTION: Previous studies have indicated that low-intensity extracorporeal shockwave therapy (Li-ESWT) may improve male erectile dysfunction (ED) of vascular aetiology. AIM: To investigate penile rehabilitation of Li-ESWT in a randomized, placebo-controlled trial in men with ED following robotic nerve-sparing radical prostatectomy (RARP). METHODS: Included were men with ED following nerve-sparing RP with a score <22 in the 5-item International Index of Erectile Function (IIEF-5) questionnaire. Participants were divided into an active A (n = 20) and a placebo/sham B group (n = 18). They were randomized consecutively upon study entry. Each study arm had one treatment a week for 5 weeks. MAIN OUTCOME MEASURES: Sexual outcomes were assessed by international validated questionnaires, Erection Hardness Score (EHS) and IIEF-5 at baseline and at 4 and 12 weeks after treatment. RESULTS: A total of 38 (n = 38) participants were enrolled; there were no dropouts. A significant increase was observed in IIEF-5 and EHS in group A at both 4 and 12 weeks. At 12 weeks, the mean IIEF-5 score had increased by 3.45 points (P = .026), while the mean EHS score had increased by 0.5 points (P= .019). CONCLUSION: This randomized study indicates that Li-ESWT for ED in men undergone RP might be effective and safe. However, further and more robust research is needed before Li-ESWT can be characterized as a reliable treatment modality. Ladegaard PBJ, Mortensen J, Skov-Jeppesen SM, et al. Erectile Dysfunction A Prospective Randomized Placebo-Controlled Study Evaluating the Effect of Low-Intensity Extracorporeal Shockwave Therapy (LI-ESWT) in Men With Erectile Dysfunction Following Radical Prostatectomy. Sex Med 2021;9:100338.

Biophysical model of coral population connectivity in the Arabian/Persian Gulf.

The coral reef ecosystems of the Arabian/Persian Gulf (the Gulf) are facing profound pressure from climate change (extreme temperatures) and anthropogenic (land-use and population-related) stressors. Increasing degradation at local and regional scales has already resulted in widespread coral cover reduction. Connectivity, the transport and exchange of larvae among geographically separated populations, plays an essential role in recovery and maintenance of biodiversity and resilience of coral reef populations. Here, an oceanographic model in 3-D high-resolution was used to simulate particle dispersion of "virtual larvae." We investigated the potential physical connectivity of coral reefs among different regions in the Gulf. Simulations reveal that basin-scale circulation is responsible for broader spatial dispersion of the larvae in the central region of the Gulf, and tidally-driven currents characterized the more localized connectivity pattern in regions along the shores in the Gulf's southern part. Results suggest predominant self-recruitment of reefs with highest source and sink ratios along the Bahrain and western Qatar coasts, followed by the south eastern Qatar and continental Abu Dhabi coast. The central sector of the Gulf is suggested as recruitment source in a stepping-stone dynamics. Recruitment intensity declined moving away from the Straits of Hormuz. Connectivity varied in models assuming passive versus active mode of larvae movement. This suggests that larval behaviour needs to be taken into consideration when establishing dispersion models, and establishing conservation strategies for these vulnerable ecosystems.

Diastereomeric Cyclopentane-Based Maltosides (CPMs) as Tools for Membrane Protein Study.

Amphiphilic agents, called detergents, are invaluable tools for studying membrane proteins. However, membrane proteins encapsulated by conventional head-to-tail detergents tend to denature or aggregate, necessitating the development of structurally distinct molecules with improved efficacy. Here, a novel class of diastereomeric detergents with a cyclopentane core unit, designated cyclopentane-based maltosides (CPMs), were prepared and evaluated for their ability to solubilize and stabilize several model membrane proteins. A couple of CPMs displayed enhanced behavior compared with the benchmark conventional detergent, n-dodecyl-ß-d-maltoside (DDM), for all the tested membrane proteins including two G-protein-coupled receptors (GPCRs). Furthermore, CPM-C12 was notable for its ability to confer enhanced membrane protein stability compared with the previously developed conformationally rigid NBMs [J. Am. Chem. Soc. 2017, 139, 3072] and LMNG. The effect of the individual CPMs on protein stability varied depending on both the detergent configuration (cis/trans) and alkyl chain length, allowing us draw conclusions on the detergent structure-property-efficacy relationship. Thus, this study not only provides novel detergent tools useful for membrane protein research but also reports on structural features of the detergents critical for detergent efficacy in stabilizing membrane proteins.

Pendant-bearing glucose-neopentyl glycol (P-GNG) amphiphiles for membrane protein manipulation: Importance of detergent pendant chain for protein stabilization.

Glucoside detergents are successfully used for membrane protein crystallization mainly because of their ability to form small protein-detergent complexes. In a previous study, we introduced glucose neopentyl glycol (GNG) amphiphiles with a branched diglucoside structure that has facilitated high resolution crystallographic structure determination of several membrane proteins. Like other glucoside detergents, however, these GNGs were less successful than DDM in stabilizing membrane proteins, limiting their wide use in protein structural study. As a strategy to improve GNG efficacy for protein stabilization, we introduced two different alkyl chains (i.e., main and pendant chains) into the GNG scaffold while maintaining the branched diglucoside head group. Of these pendant-bearing GNGs (P-GNGs), three detergents (GNG-2,14, GNG-3,13 and GNG-3,14) were not only notably better than both DDM (a gold standard detergent) and the previously described GNGs at stabilizing all six membrane proteins tested here, but were also as efficient as DDM at membrane protein extraction. The results suggest that the C14 main chain of the P-GNGs is highly compatible with the hydrophobic widths of membrane proteins, while the C2/C3 pendant chain is effective at strengthening detergent hydrophobic interactions. Based on the marked effect on protein stability and solubility, these glucoside detergents hold significant potential for membrane protein structural study. Furthermore, the independent roles of the detergent two alkyl chains first introduced in this study have shed light on new amphiphile design for membrane protein study. STATEMENT OF SIGNIFICANCE: Detergent efficacy for protein stabilization tends to be protein-specific, thus it is challenging to find a detergent that is effective at stabilizing multiple membrane proteins. By incorporating a pendant chain into our previous GNG scaffold, we prepared pendant chain-bearing GNGs (P-GNGs) and identified three P-GNGs that were highly effective at stabilizing all membrane proteins tested here including two GPCRs. In addition, the new detergents were as efficient as DDM at extracting membrane proteins, enabling use of these detergents over the multiple steps of protein isolation. The key difference between the P-GNGs and other glucoside detergents, the presence of a pendant chain, is likely to be responsible for their markedly enhanced protein stabilization behavior.

New Malonate-Derived Tetraglucoside Detergents for Membrane Protein Stability.

Membrane proteins are widely studied in detergent micelles, a membrane-mimetic system formed by amphiphilic compounds. However, classical detergents have serious limitations in their utility, particularly for unstable proteins such as eukaryotic membrane proteins and membrane protein complexes, and thus, there is an unmet need for novel amphiphiles with enhanced ability to stabilize membrane proteins. Here, we developed a new class of malonate-derived detergents with four glucosides, designated malonate-derived tetra-glucosides (MTGs), and compared these new detergents with previously reported octyl glucose neopentyl glycol (OGNG) and n-dodecyl-ß-d-maltoside (DDM). When tested with two G-protein coupled receptors (GPCRs) and three transporters, a couple of MTGs consistently conferred enhanced stability to all tested proteins compared to DDM and OGNG. As a result of favorable behaviors for a range of membrane proteins, these MTGs have substantial potential for membrane protein research. This study additionally provides a new detergent design principle based on the effect of a polar functional group (i.e., ether) on protein stability depending on its position in the detergent scaffold.

X-ray structure of LeuT in an inward-facing occluded conformation reveals mechanism of substrate release.

Neurotransmitter:sodium symporters (NSS) are conserved from bacteria to man and serve as targets for drugs, including antidepressants and psychostimulants. Here we report the X-ray structure of the prokaryotic NSS member, LeuT, in a Na+/substrate-bound, inward-facing occluded conformation. To obtain this structure, we were guided by findings from single-molecule fluorescence spectroscopy and molecular dynamics simulations indicating that L-Phe binding and mutation of the conserved N-terminal Trp8 to Ala both promote an inward-facing state. Compared to the outward-facing occluded conformation, our structure reveals a major tilting of the cytoplasmic end of transmembrane segment (TM) 5, which, together with release of the N-terminus but without coupled movement of TM1, opens a wide cavity towards the second Na+ binding site. The structure of this key intermediate in the LeuT transport cycle, in the context of other NSS structures, leads to the proposal of an intracellular release mechanism of substrate and ions in NSS proteins.

Short-Range Distance Measurement by Transition Metal Ion FRET.

Measurement of atomic-scale conformational dynamics in proteins has proved a challenging endeavor, although these movements are pivotal for understanding the mechanisms behind protein function. Herein we describe a fluorescence-based method that enables the measurement of distances between specific domains within a protein and how it might change during protein function. The method is transition metal ion Förster resonance energy transfer (tmFRET) and builds on the principle that the fluorescence emission from a fluorophore can be quenched in a distance-dependent manner by a colored transition metal such as nickel (Ni2+), copper (Cu2+), or cobalt (Co2+). It can be applied to literally any protein where it is possible to perform site-specific incorporation of a fluorescent molecule. This chapter will explain the use and applications of tmFRET in detail using incorporation of the dye with cysteine chemistry on a purified protein sample.

Conformationally Restricted Monosaccharide-Cored Glycoside Amphiphiles: The Effect of Detergent Headgroup Variation on Membrane Protein Stability.

Detergents are widely used to isolate membrane proteins from lipid bilayers, but many proteins solubilized in conventional detergents are structurally unstable. Thus, there is major interest in the development of novel amphiphiles to facilitate membrane protein research. In this study, we have designed and synthesized novel amphiphiles with a rigid scyllo-inositol core, designated scyllo-inositol glycosides (SIGs). Varying the headgroup structure allowed the preparation of three sets of SIGs that were evaluated for their effects on membrane protein stability. When tested with a few model membrane proteins, representative SIGs conferred enhanced stability to the membrane proteins compared to a gold standard conventional detergent (DDM). Of the novel amphiphiles, a SIG designated STM-12 was most effective at preserving the stability of the multiple membrane proteins tested here. In addition, a comparative study of the three sets suggests that several factors, including micelle size and alkyl chain length, need to be considered in the development of novel detergents for membrane protein research. Thus, this study not only describes new detergent tools that are potentially useful for membrane protein structural study but also introduces plausible correlations between the chemical properties of detergents and membrane protein stabilization efficacy.

Self-Assembly Behavior and Application of Terphenyl-Cored Trimaltosides for Membrane-Protein Studies: Impact of Detergent Hydrophobic Group Geometry on Protein Stability.

Amphipathic agents are widely used in various fields including biomedical sciences. Micelle-forming detergents are particularly useful for in vitro membrane-protein characterization. As many conventional detergents are limited in their ability to stabilize membrane proteins, it is necessary to develop novel detergents to facilitate membrane-protein research. In the current study, we developed novel trimaltoside detergents with an alkyl pendant-bearing terphenyl unit as a hydrophobic group, designated terphenyl-cored maltosides (TPMs). We found that the geometry of the detergent hydrophobic group substantially impacts detergent self-assembly behavior, as well as detergent efficacy for membrane-protein stabilization. TPM-Vs, with a bent terphenyl group, were superior to the linear counterparts (TPM-Ls) at stabilizing multiple membrane proteins. The favorable protein stabilization efficacy of these bent TPMs is likely associated with a binding mode with membrane proteins distinct from conventional detergents and facial amphiphiles. When compared to n-dodecyl-ß-d-maltoside (DDM), most TPMs were superior or comparable to this gold standard detergent at stabilizing membrane proteins. Notably, TPM-L3 was particularly effective at stabilizing the human ß2 adrenergic receptor (ß2 AR), a G-protein coupled receptor, and its complex with Gs protein. Thus, the current study not only provides novel detergent tools that are useful for membrane-protein study, but also suggests a critical role for detergent hydrophobic group geometry in governing detergent efficacy.

Correction: Trehalose-cored amphiphiles for membrane protein stabilization: importance of the detergent micelle size in GPCR stability.

Correction for 'Trehalose-cored amphiphiles for membrane protein stabilization: importance of the detergent micelle size in GPCR stability' by Manabendra Das et al., Org. Biomol. Chem., 2019, 17, 3249-3257.

Self-Assembly Behaviors of a Penta-Phenylene Maltoside and Its Application for Membrane Protein Study.

We prepared an amphiphile with a penta-phenylene lipophilic group and a branched trimaltoside head group. This new agent, designated penta-phenylene maltoside (PPM), showed a marked tendency to self-assembly into micelles via strong aromatic-aromatic interactions in aqueous media, as evidenced by 1 H NMR spectroscopy and fluorescence studies. When utilized for membrane protein studies, this new agent was superior to DDM, a gold standard conventional detergent, in stabilizing multiple proteins long term. The ability of this agent to form aromatic-aromatic interactions is likely responsible for enhanced protein stabilization when associated with a target membrane protein.

Trehalose-cored amphiphiles for membrane protein stabilization: importance of the detergent micelle size in GPCR stability.

Despite their importance in biology and medicinal chemistry, structural and functional studies of membrane proteins present major challenges. To study diverse membrane proteins, it is crucial to have the correct detergent to efficiently extract and stabilize the proteins from the native membranes for biochemical/biophysical downstream analyses. But many membrane proteins, particularly eukaryotic ones, are recalcitrant to stabilization and/or crystallization with currently available detergents and thus there are major efforts to develop novel detergents with enhanced properties. Here, a novel class of trehalose-cored amphiphiles are introduced, with multiple alkyl chains and carbohydrates projecting from the trehalose core unit are introduced. A few members displayed enhanced protein stabilization behavior compared to the benchmark conventional detergent, n-dodecyl-ß-d-maltoside (DDM), for multiple tested membrane proteins: (i) a bacterial leucine transporter (LeuT), (ii) the R. capsulatus photosynthetic superassembly, and (iii) the human ß2 adrenergic receptor (ß2AR). Due to synthetic convenience and their favourable behaviors for a range of membrane proteins, these agents have potential for membrane protein research. In addition, the detergent property-efficacy relationship discussed here will guide future design of novel detergents.

[Indications and application of extracorporeal shockwave therapy].

Extracorporeal shockwave therapy (ESWT) is a novel treatment modality to stimulate tissue regeneration and anti-fibrosis. In this review, we summarise the use of ESWT for erectile dysfunction (ED), diabetic foot ulcers (DFU), Peyronie's disease (PD), chronic kidney disease (CKD), and scleroderma. Several randomised clinical trials demonstrate the efficacy of ESWT for vasculogenic ED and DFU, and ESWT may also relieve pain in patients with PD. ESWT is still experimental for CKD and scleroderma. In general, ESWT is associated with few and mild adverse effects.