A hydrophobic funnel governs monovalent cation selectivity in the ion channel TRPM5.

A key capability of ion channels is the facilitation of selective permeation of certain ionic species across cellular membranes at high rates. Due to their physiological significance, ion channels are of great pharmaceutical interest as drug targets. The polymodal signal-detecting transient receptor potential (TRP) superfamily of ion channels forms a particularly promising group of drug targets. While most members of this family permeate a broad range of cations including Ca2+, TRPM4 and TRPM5 are unique due to their strong monovalent selectivity and impermeability for divalent cations. Here, we investigated the mechanistic basis for their unique monovalent selectivity by in silico electrophysiology simulations of TRPM5. Our simulations reveal an unusual mechanism of cation selectivity, which is underpinned by the function of the central channel cavity alongside the selectivity filter. Our results suggest that a subtle hydrophobic barrier at the cavity entrance ("hydrophobic funnel") enables monovalent but not divalent cations to pass and occupy the cavity at physiologically relevant membrane voltages. Monovalent cations then permeate efficiently by a cooperative, distant knock-on mechanism between two binding regions in the extracellular pore vestibule and the central cavity. By contrast, divalent cations do not enter or interact favorably with the channel cavity due to its raised hydrophobicity. Hydrophilic mutations in the transition zone between the selectivity filter and the central channel cavity abolish the barrier for divalent cations, enabling both monovalent and divalent cations to traverse TRPM5.

Accelerated elastin degradation by age-disease interaction: a common feature in age-related diseases.

Aging is a major driving force for many diseases but the relationship between chronological age, the aging process and age-related diseases is not fully understood. Fragmentation and loss of ultra-long-lived elastin are key features in aging and several age-related diseases leading to increased mortality. By comparing the relationship between age and elastin turnover with healthy volunteers, we show that accelerated elastin turnover by age-disease interaction is a common feature of age-related diseases.

Reconstruction of partial auricular skin cancer defects: a review of current techniques.

PURPOSE OF REVIEW: To discuss the principles of auricular reconstruction and review recently published literature in the field. RECENT FINDINGS: Auricular reconstruction poses several challenges to the surgeon aiming to restore form and function following skin cancer resection. Various techniques have been described in the literature with many modifications also reported to address their shortcomings. An algorithmic approach based on the location and composition of the defect is recommended. In many instances, more than one technique can be used, and the operating surgeon should be familiar with these to determine the optimal approach for the individual patient. SUMMARY: This review highlights the updates in well established techniques as well as modern modifications. Furthermore, a framework for decision-making in auricular reconstruction is presented.

A cooperative knock-on mechanism underpins Ca2+-selective cation permeation in TRPV channels.

The selective exchange of ions across cellular membranes is a vital biological process. Ca2+-mediated signaling is implicated in a broad array of physiological processes in cells, while elevated intracellular concentrations of Ca2+ are cytotoxic. Due to the significance of this cation, strict Ca2+ concentration gradients are maintained across the plasma and organelle membranes. Therefore, Ca2+ signaling relies on permeation through selective ion channels that control the flux of Ca2+ ions. A key family of Ca2+-permeable membrane channels is the polymodal signal-detecting transient receptor potential (TRP) ion channels. TRP channels are activated by a wide variety of cues including temperature, small molecules, transmembrane voltage, and mechanical stimuli. While most members of this family permeate a broad range of cations non-selectively, TRPV5 and TRPV6 are unique due to their strong Ca2+ selectivity. Here, we address the question of how some members of the TRPV subfamily show a high degree of Ca2+ selectivity while others conduct a wider spectrum of cations. We present results from all-atom molecular dynamics simulations of ion permeation through two Ca2+-selective and two non-selective TRPV channels. Using a new method to quantify permeation cooperativity based on mutual information, we show that Ca2+-selective TRPV channel permeation occurs by a three-binding site knock-on mechanism, whereas a two-binding site knock-on mechanism is observed in non-selective TRPV channels. Each of the ion binding sites involved displayed greater affinity for Ca2+ over Na+. As such, our results suggest that coupling to an extra binding site in the Ca2+-selective TRPV channels underpins their increased selectivity for Ca2+ over Na+ ions. Furthermore, analysis of all available TRPV channel structures shows that the selectivity filter entrance region is wider for the non-selective TRPV channels, slightly destabilizing ion binding at this site, which is likely to underlie mechanistic decoupling.

The Role of Smoking in Asthma and Chronic Obstructive Pulmonary Disease Overlap.

Exposure to cigarette smoke has a key role in the development, adverse health outcomes, and impaired response to some therapies among individuals with features of asthma and chronic obstructive pulmonary disease overlap (ACO). To aid the identification of clinical subtypes, the description of ever smokers with features of asthma and COPD should include data on smoking status, cumulative smoking history, and the phenotype of asthma and smoking-related chronic airway disease. Pathogenic mechanisms in smoking-related ACO involve poorly understood, complex interactions between smoking-induced and asthma-induced airway inflammation, corticosteroid insensitivity, and tissue remodeling. Evidence for the clinical effectiveness of interventions for adults with smoking-related ACO is limited. Management currently involves the identification and targeting of treatable traits such as current smoking, type 2 high eosinophilic inflammation, symptomatic airflow obstruction, and extrapulmonary comorbidities.

Transport and targeted binding of Pluronic-coated nanoparticles in unsaturated porous media.

The effectiveness of most in situ remedial technologies, including nanoremediation, lies on successful delivery of reagents to a subsurface target treatment zone. Targeted delivery of engineered nanoparticles (NPs) to treat petroleum hydrocarbons present in the unsaturated zone requires an understanding of their transport behaviour in these systems. A series of column experiments explored the effect of initial water saturation, flowrate, input dosage, and porous medium texture on the transport of iron oxide or cobalt ferrite NPs coated with an amphiphilic co-polymer, as well as their targeted attachment to a crude oil zone. As the initial water content increased with a concomitant reduction in air saturation, the degree of tailing present in the NP breakthrough curves (BTCs) reduced, and the mass of NPs recovered increased. Air saturation is positively correlated with the magnitude of air-water interfaces, which provide additional NP retention sites. At a lower injection flow rate, NP retention increased due to a longer residence time and comparatively high air saturation. NP transport behaviour was not sensitive to NP injection dose over the range tested. Increased retention and retardation of the NP BTC was observed in sediments with a higher clay and silt content. NPs coated with a lower concentration of a Pluronic block co-polymer to promote binding were preferentially retained within the crude oil zone. To simulate the asymmetrical NP breakthrough curves observed from the unsaturated systems required the use of a model that accounted for both mobile and immobile flow regions as well as NP attachment and detachment with nonlinear Langmuirian blocking. This model allowed examination of attachment and detachment rate coefficients which captured NP interaction with the porous medium and/or crude oil. It was found that the initial water saturation and flow rate did not have an appreciable impact on the NP attachment rate coefficient, while it increased by ~10× with increasing clay and silt content, and by ~100× in the presence of crude oil, indicating preferential NP attachment within the crude oil zone. As a result of the lower NP polymer concentration coating used to promote increased attachment to crude oil, higher retention was observed near the column inlet and was captured quantitatively by adding a depth-dependent straining term to the model. This retention behaviour represents a combination of irreversible attachment at the air-water interfaces and straining near the column inlet enhanced by the formation of NP aggregates. The detachment rate coefficient decreased with a lower initial water saturation and flowrate, but increased with higher clay and silt content. The findings from this study contribute to our understanding of the transport and binding behaviour of Pluronic-coated NPs in unsaturated conditions and, in particular, the role of initial water content, flowrate and porous medium texture. Demonstrated delivery of NPs to a target zone is an important step towards expanding the utility of NPs as treatment reagents.

Cigarette Smoking and Asthma.

Globally, around half the adult asthma population are current or former cigarette smokers. Cigarette smoking and asthma interact to induce an "asthma-smoking phenotype(s)," which has important implications for diagnosis, pathogenic mechanisms, and management. The lack of progress in understanding the effects of smoking on adults with asthma is due in part to their exclusion from most investigative studies and large clinical trials. In this review, we summarize the adverse clinical outcomes associated with cigarette smoking in asthma, highlight challenges in diagnosing asthma among cigarette smokers with chronic respiratory symptoms, particularly in older individuals with a long-standing smoking history, and review pathogenic mechanisms involving smoking- and asthma-related airway inflammation, tissue remodeling, corticosteroid insensitivity, and low-grade systemic inflammation. We discuss the key components of management including the importance of smoking cessation strategies, evidence for the effectiveness of the Global Initiative for Asthma recommendations on treatment in cigarette smokers, and the role of treatable traits such as type 2 eosinophilic airway inflammation. Lastly, we provide an algorithm to aid clinicians to manage current and former smokers with asthma. In the future, controlled and pragmatic trials in real-world populations should include cigarette smokers with asthma to provide an evidence base for treatment recommendations.

Neuroendocrine liver metastases - 'doughnut box sign' on SPECT/CT.

A 76 year old patient was referred for Indium111 Octreotide scan to look for primary tumour and extent of neuroendocrine metastases. Indium 111 Octreotide scan showed a liver packed with centrally necrotic metastases like doughnuts packed in a box. No primary lesion was identified in this scan.

Spatiotemporal geo-electrical sensing of a Pluronic-coated cobalt ferrite nanoparticle slug in natural sand flow-through columns.

Rising industrial interest in the application of nanomaterials for the remediation of contaminated sites has led to concern over the environmental fate of the nanoremediation agents used. A critical requirement in evaluating and understanding nanoparticle (NP) behaviour in porous media is the development of analytical methods capable of in situ monitoring of complex NP transport dynamics. Spectral induced polarization (SIP), a non-invasive geo-electrical technique, offers a promising tool for detecting and quantifying NPs in soil and aquifer media. However, its application for monitoring the spatial migration and attachment behaviour of NPs remains uninvestigated. Here, we present results from flow-through experiments where we monitored the transport of cobalt ferrite nanoparticles (CoFe-NPs) coated with Pluronic, an amphiphilic polymer, in natural aquifer sand columns. We coupled concentration breakthrough curve analysis with SIP monitoring and reactive transport modeling to relate spatiotemporal NP concentration distributions to geo-electrical signals. Changes in the real (σ') conductivity at three different locations along the columns closely correlated with model-computed total (solid plus aqueous phase) NP concentrations during the propagation of a NP slug. The imaginary conductivity (σ″) correlated closely with the arrival of the NP-slug. However, during the receding front, bimodal σ″-signal peak behaviour was observed propagating through the columns, indicating the existence of complex in situ NP transport dynamics, potentially revealing the rupture of nanoclusters upon straining and their effect on bulk charge storage that may not be obvious from breakthrough curve data alone. Fitting of a double Cole-Cole relaxation model yielded distinct shifts in relaxation time (τ) associated with the polarization of smaller length-scale particles. Post-NP pulse τ and σ″ did not return to pre-injection values; these lingering signals were caused by retained NP concentrations as low as 8.8 mg kg-1. Our results support the applicability of SIP for spatial and temporal monitoring of NP distributions, with implications for the investigation of NP transport and nanoremediation strategies.

Factors Associated with Frequent Exacerbations in the UK Severe Asthma Registry.

BACKGROUND: Frequent exacerbations are an important cause of morbidity in patients with severe asthma. OBJECTIVE: Our aim was to identify factors associated with frequent exacerbations in a large well-characterized severe asthma population and determine whether factors differed in patients treated with and without maintenance oral corticosteroids (OCS). METHODS: Adults with severe asthma from specialized asthma centers across the United Kingdom were recruited to the UK Severe Asthma Registry. Demography, comorbidities and physiological measurements were collected. We conducted univariable and multivariable logistic regression analyses to identify factors associated with frequent exacerbations, defined as 3 or more exacerbations treated with high-dose systemic corticosteroids in the past year. RESULTS: Of 1,592 patients with severe asthma from the UK Severe Asthma Registry, 1,137 (71%) were frequent exacerbators and 833 (52%) were on maintenance OCS. The frequent exacerbators were more likely to be ex-smokers, have gastroesophageal reflux disease, higher Asthma Control Questionnaire-6 (ACQ-6) score, and higher blood eosinophilia. Multivariable regression analyses showed ACQ-6 score greater than 1.5 (odds ratio [OR] 4.25; P < .001), past smoking history (OR 1.55; P = .024), and fractional exhaled nitric oxide greater than 50ppb (OR 1.54; P = .044) were independently associated with frequent exacerbations. Past smoking history correlated with frequent exacerbations only in patients on maintenance OCS (OR 2.25; P = .004), whereas ACQ-6 score greater than 1.5 was independently associated with frequent exacerbations in those treated with and without maintenance OCS (OR 2.74; P = .017 and OR 6.42; P < .001, respectively). CONCLUSIONS: Several factors were associated with frequent exacerbations in a large UK severe asthma registry population. High ACQ-6 score had the strongest association with frequent exacerbations irrespective of maintenance OCS status.

Phenotypic and functional translation of IL33 genetics in asthma.

BACKGROUND: Asthma is a complex disease with multiple phenotypes that may differ in disease pathobiology and treatment response. IL33 single nucleotide polymorphisms (SNPs) have been reproducibly associated with asthma. IL33 levels are elevated in sputum and bronchial biopsies of patients with asthma. The functional consequences of IL33 asthma SNPs remain unknown. OBJECTIVE: This study sought to determine whether IL33 SNPs associate with asthma-related phenotypes and with IL33 expression in lung or bronchial epithelium. This study investigated the effect of increased IL33 expression on human bronchial epithelial cell (HBEC) function. METHODS: Association between IL33 SNPs (Chr9: 5,815,786-6,657,983) and asthma phenotypes (Lifelines/DAG [Dutch Asthma GWAS]/GASP [Genetics of Asthma Severity & Phenotypes] cohorts) and between SNPs and expression (lung tissue, bronchial brushes, HBECs) was done using regression modeling. Lentiviral overexpression was used to study IL33 effects on HBECs. RESULTS: We found that 161 SNPs spanning the IL33 region associated with 1 or more asthma phenotypes after correction for multiple testing. We report a main independent signal tagged by rs992969 associating with blood eosinophil levels, asthma, and eosinophilic asthma. A second, independent signal tagged by rs4008366 presented modest association with eosinophilic asthma. Neither signal associated with FEV1, FEV1/forced vital capacity, atopy, and age of asthma onset. The 2 IL33 signals are expression quantitative loci in bronchial brushes and cultured HBECs, but not in lung tissue. IL33 overexpression in vitro resulted in reduced viability and reactive oxygen species-capturing of HBECs, without influencing epithelial cell count, metabolic activity, or barrier function. CONCLUSIONS: We identify IL33 as an epithelial susceptibility gene for eosinophilia and asthma, provide mechanistic insight, and implicate targeting of the IL33 pathway specifically in eosinophilic asthma.

Ultrasound-triggered therapeutic microbubbles enhance the efficacy of cytotoxic drugs by increasing circulation and tumor drug accumulation and limiting bioavailability and toxicity in normal tissues.

Most cancer patients receive chemotherapy at some stage of their treatment which makes improving the efficacy of cytotoxic drugs an ongoing and important goal. Despite large numbers of potent anti-cancer agents being developed, a major obstacle to clinical translation remains the inability to deliver therapeutic doses to a tumor without causing intolerable side effects. To address this problem, there has been intense interest in nanoformulations and targeted delivery to improve cancer outcomes. The aim of this work was to demonstrate how vascular endothelial growth factor receptor 2 (VEGFR2)-targeted, ultrasound-triggered delivery with therapeutic microbubbles (thMBs) could improve the therapeutic range of cytotoxic drugs. Methods: Using a microfluidic microbubble production platform, we generated thMBs comprising VEGFR2-targeted microbubbles with attached liposomal payloads for localised ultrasound-triggered delivery of irinotecan and SN38 in mouse models of colorectal cancer. Intravenous injection into tumor-bearing mice was used to examine targeting efficiency and tumor pharmacodynamics. High-frequency ultrasound and bioluminescent imaging were used to visualise microbubbles in real-time. Tandem mass spectrometry (LC-MS/MS) was used to quantitate intratumoral drug delivery and tissue biodistribution. Finally, 89Zr PET radiotracing was used to compare biodistribution and tumor accumulation of ultrasound-triggered SN38 thMBs with VEGFR2-targeted SN38 liposomes alone. Results: ThMBs specifically bound VEGFR2 in vitro and significantly improved tumor responses to low dose irinotecan and SN38 in human colorectal cancer xenografts. An ultrasound trigger was essential to achieve the selective effects of thMBs as without it, thMBs failed to extend intratumoral drug delivery or demonstrate enhanced tumor responses. Sensitive LC-MS/MS quantification of drugs and their metabolites demonstrated that thMBs extended drug exposure in tumors but limited exposure in healthy tissues, not exposed to ultrasound, by persistent encapsulation of drug prior to elimination. 89Zr PET radiotracing showed that the percentage injected dose in tumors achieved with thMBs was twice that of VEGFR2-targeted SN38 liposomes alone. Conclusions: thMBs provide a generic platform for the targeted, ultrasound-triggered delivery of cytotoxic drugs by enhancing tumor responses to low dose drug delivery via combined effects on circulation, tumor drug accumulation and exposure and altered metabolism in normal tissues.

Factors affecting pluronic-coated iron oxide nanoparticle binding to petroleum hydrocarbon-impacted sediments.

Effective targeted delivery of nanoparticle agents may enhance the remediation of soils and site characterization efforts. Nanoparticles coated with Pluronic, an amphiphilic block co-polymer, demonstrated targeted binding behaviour toward light non-aqueous phase liquids such as heavy crude oil. Various factors including coating concentration, oil concentration, oil type, temperature, and pH were assessed to determine their effect on nanoparticle binding to heavy crude oil-impacted sandy aquifer material. Nanoparticle binding was increased by decreasing the coating concentration, increasing oil concentration, using heavier oil types, and increasing temperature, while pH over the range of 5-9 was found to have no effect. Nanoparticle transport and binding in columns packed with clean and oily porous media demonstrated the ability for efficient nanoparticle targeted binding. For the conditions explored, the attachment rate coefficient in columns packed with clean sand was 2.10 ± 0.66 × 10-4 s-1; however, for columns packed with oil-impacted sand a minimum attachment rate coefficient of 8.86 ± 0.43 × 10-4 s-1 was estimated. The higher attachment rate for the oil-impacted sand system indicates that nanoparticles may preferentially accumulate to oil-impacted zones present at heterogeneous impacted sites. Simulations were used to demonstrate this hypothesis using the set of parameters generated in this effort. This work contributes to our understanding of the application conditions that are required for efficient targeted binding of nanoparticles to crude-oil impacted porous media.

Phenotypic and functional translation of IL1RL1 locus polymorphisms in lung tissue and asthmatic airway epithelium.

The IL1RL1 (ST2) gene locus is robustly associated with asthma; however, the contribution of single nucleotide polymorphisms (SNPs) in this locus to specific asthma subtypes and the functional mechanisms underlying these associations remain to be defined. We tested for association between IL1RL1 region SNPs and characteristics of asthma as defined by clinical and immunological measures and addressed functional effects of these genetic variants in lung tissue and airway epithelium. Utilizing 4 independent cohorts (Lifelines, Dutch Asthma GWAS [DAG], Genetics of Asthma Severity and Phenotypes [GASP], and Manchester Asthma and Allergy Study [MAAS]) and resequencing data, we identified 3 key signals associated with asthma features. Investigations in lung tissue and primary bronchial epithelial cells identified context-dependent relationships between the signals and IL1RL1 mRNA and soluble protein expression. This was also observed for asthma-associated IL1RL1 nonsynonymous coding TIR domain SNPs. Bronchial epithelial cell cultures from asthma patients, exposed to exacerbation-relevant stimulations, revealed modulatory effects for all 4 signals on IL1RL1 mRNA and/or protein expression, suggesting SNP-environment interactions. The IL1RL1 TIR signaling domain haplotype affected IL-33-driven NF-κB signaling, while not interfering with TLR signaling. In summary, we identify that IL1RL1 genetic signals potentially contribute to severe and eosinophilic phenotypes in asthma, as well as provide initial mechanistic insight, including genetic regulation of IL1RL1 isoform expression and receptor signaling.