Cost-effectiveness analysis of biologics for the treatment of chronic rhinosinusitis with nasal polyps in Canada.

BACKGROUND: Dupilumab, omalizumab, and mepolizumab are the three biologics currently approved for use in CRSwNP in Canada. Despite evidence of efficacy, their cost-effectiveness, which is a key factor influencing prescribing patterns, has not yet been compared to each other. METHODS: A cost-effectiveness model using quality-adjusted life years (QALYs) was constructed using a Decision Tree Markov analysis. A third-party healthcare payer perspective and a 10-year time horizon was used. A willingness-to-pay (WTP) threshold of 50,000 Canadian dollars (CAD) per QALY was used to determine cost-effectiveness. Dupilumab, omalizumab, and mepolizumab were each compared to each other. RESULTS: Omalizumab was the most cost-effective biologic using current estimates of cost and efficacy in CRSwNP. Using omalizumab as a baseline, dupilumab had an ICER of $235,305/QALY. Mepolizumab was dominated by omalizumab and dupilumab at the current drug prices and estimates of efficacy. Sensitivity analyses determined that when increasing the WTP threshold to $150,000/QALY, dupilumab became cost-effective compared to omalizumab in 22.5% of simulation scenarios. Additionally, altering dosing frequency had a significant effect on cost-effectiveness. CONCLUSION: When comparing the relative cost-effectiveness of biologics in recalcitrant CRSwNP, omalizumab currently appears to be the most cost-effective option. Future reductions in drug prices, adjustments to currently approved dosing regimens, better patient selection, and improvements in sinus surgery outcomes will challenge the current cost-effectiveness models and necessitate reassessment as treatments for CRSwNP continue to evolve.

America's Opioid Ecosystem: How Leveraging System Interactions Can Help Curb Addiction, Overdose, and Other Harms.

Opioids play an outsized role in America's drug problems, but they also play a critically important role in medicine. Thus, they deserve special attention. Illegally manufactured opioids (such as fentanyl) are involved in a majority of U.S. drug overdoses, but the problems are broader and deeper than drug fatalities. Depending on the drugs involved, there can be myriad physical and mental health consequences associated with having a substance use disorder. And it is not just those using drugs who suffer. Substance use and related behaviors can significantly affect individuals' families, friends, employers, and wider communities. Efforts to address problems related to opioids are insufficient and sometimes contradictory. Researchers provide a nuanced assessment of America's opioid ecosystem, highlighting how leveraging system interactions can reduce addiction, overdose, suffering, and other harms. At the core of the opioid ecosystem are the individuals who use opioids and their families. Researchers also include detail on ten major components of the opioid ecosystem: substance use disorder treatment, harm reduction, medical care, the criminal legal system, illegal supply and supply control, first responders, the child welfare system, income support and homeless services, employment, and education. The primary audience for this study is policymakers, but it should also be useful for foundations looking for opportunities to create change that have often been overlooked. This study can help researchers better consider the full consequences of policy changes and help members of the media identify the dynamics of interactions that deserve more attention.

Cytosolic and mitochondrial translation elongation are coordinated through the molecular chaperone TRAP1 for the synthesis and import of mitochondrial proteins.

A complex interplay between mRNA translation and cellular respiration has been recently unveiled, but its regulation in humans is poorly characterized in either health or disease. Cancer cells radically reshape both biosynthetic and bioenergetic pathways to sustain their aberrant growth rates. In this regard, we have shown that the molecular chaperone TRAP1 not only regulates the activity of respiratory complexes, behaving alternatively as an oncogene or a tumor suppressor, but also plays a concomitant moonlighting function in mRNA translation regulation. Herein, we identify the molecular mechanisms involved, showing that TRAP1 (1) binds both mitochondrial and cytosolic ribosomes, as well as translation elongation factors; (2) slows down translation elongation rate; and (3) favors localized translation in the proximity of mitochondria. We also provide evidence that TRAP1 is coexpressed in human tissues with the mitochondrial translational machinery, which is responsible for the synthesis of respiratory complex proteins. Altogether, our results show an unprecedented level of complexity in the regulation of cancer cell metabolism, strongly suggesting the existence of a tight feedback loop between protein synthesis and energy metabolism, based on the demonstration that a single molecular chaperone plays a role in both mitochondrial and cytosolic translation, as well as in mitochondrial respiration.

Azithromycin Mechanisms of Action in CRS Include Epithelial Barrier Restoration and Type 1 Inflammation Reduction.

OBJECTIVE: Previous in vitro transcriptomic profiling suggests azithromycin exerts its effects in patients with chronic rhinosinusitis (CRS) via modulation of type 1 inflammation and restoration of epithelial barrier function. We wished to verify these postulated effects using in vitro models of epithelial repair and in vivo transcriptional profiling. STUDY DESIGN: Functional effects of azithromycin in CRS were verified using in vitro models of wounding. The mechanism of the effect of azithromycin was assessed in vivo using transcriptomic profiling. SETTING: Academic medical center. METHODS: Effects of azithromycin on the speed of epithelial repair were verified in a wounding model using primary nasal epithelial cells (pNEC) from CRS patients. Nasal brushings collected pre-and posttreatment during a placebo-controlled trial of azithromycin for CRS patients unresponsive to surgery underwent transcriptomic profiling to identify implicated pathways. RESULTS: Administration of azithromycin improved the wound healing rates in CRS pNECs and prevented the negative effect of Staphylococcus aureus on epithelial repair. In vivo, response to azithromycin was associated with downregulation in pathways of type 1 inflammation, and upregulation of pathways implicated in the restoration of the cell cycle. CONCLUSION: Restoration of healthy epithelial function may represent a major mode of action of azithromycin in CRS. In vitro models show enhanced epithelial repair, while in vivo transcriptomics shows downregulation of pathways type 1 inflammation accompanied by upregulation of DNA repair and cell-cycle pathways. The maximal effect in patients with high levels of type 1-enhanced inflammation suggests that azithromycin may represent a novel therapeutic option for surgery-unresponsive CRS patients.

Synaptic gradients transform object location to action.

To survive, animals must convert sensory information into appropriate behaviours1,2. Vision is a common sense for locating ethologically relevant stimuli and guiding motor responses3-5. How circuitry converts object location in retinal coordinates to movement direction in body coordinates remains largely unknown. Here we show through behaviour, physiology, anatomy and connectomics in Drosophila that visuomotor transformation occurs by conversion of topographic maps formed by the dendrites of feature-detecting visual projection neurons (VPNs)6,7 into synaptic weight gradients of VPN outputs onto central brain neurons. We demonstrate how this gradient motif transforms the anteroposterior location of a visual looming stimulus into the fly's directional escape. Specifically, we discover that two neurons postsynaptic to a looming-responsive VPN type promote opposite takeoff directions. Opposite synaptic weight gradients onto these neurons from looming VPNs in different visual field regions convert localized looming threats into correctly oriented escapes. For a second looming-responsive VPN type, we demonstrate graded responses along the dorsoventral axis. We show that this synaptic gradient motif generalizes across all 20 primary VPN cell types and most often arises without VPN axon topography. Synaptic gradients may thus be a general mechanism for conveying spatial features of sensory information into directed motor outputs.

Cytosolic and mitochondrial translation elongation are coordinated through the molecular chaperone TRAP1 for the synthesis and import of mitochondrial proteins.

A complex interplay between mRNA translation and cellular respiration has been recently unveiled, but its regulation in humans is poorly characterized in either health or disease. Cancer cells radically reshape both biosynthetic and bioenergetic pathways to sustain their aberrant growth rates. In this regard, we have shown that the molecular chaperone TRAP1 not only regulates the activity of respiratory complexes, behaving alternatively as an oncogene or a tumor suppressor, but also plays a concomitant moonlighting function in mRNA translation regulation. Herein we identify the molecular mechanisms involved, demonstrating that TRAP1: i) binds both mitochondrial and cytosolic ribosomes as well as translation elongation factors, ii) slows down translation elongation rate, and iii) favors localized translation in the proximity of mitochondria. We also provide evidence that TRAP1 is coexpressed in human tissues with the mitochondrial translational machinery, which is responsible for the synthesis of respiratory complex proteins. Altogether, our results show an unprecedented level of complexity in the regulation of cancer cell metabolism, strongly suggesting the existence of a tight feedback loop between protein synthesis and energy metabolism, based on the demonstration that a single molecular chaperone plays a role in both mitochondrial and cytosolic translation, as well as in mitochondrial respiration.

Asociación entre neuroimagen y secuelas neurológicas en pacientes con infección congénita por citomegalovirus / Association between neuroimaging findings and neurological sequelae in patients with congenital cytomegalovirus infection

Introducción: La infección congénita por citomegalovirus (CMV) supone una importante causa de discapacidad. Existen escasas evidencias acerca del valor pronóstico de las lesiones presentes en los estudios de neuroimagen. Objetivo: Analizar la gravedad de las lesiones en la resonancia magnética (RM) y la ecografía transfontanelar, y su relación con déficits neurológicos a largo plazo. Pacientes y métodos: Se realizó un estudio observacional analítico retrospectivo de 36 pacientes con infección congénita por CMV. Se revisaron los estudios de neuroimagen y se clasificaron según la escala de Noyola et al. modificada. Se relacionaron los hallazgos de neuroimagen con la afectación neurológica en su última visita en la consulta de neuropediatría. Resultados: Un total de 36 pacientes fueron estudiados, habiéndose realizado ecografía transfontanelar en 30 y RM cerebral en 29. La ecografía transfontanelar estuvo alterada en 20/30 pacientes, de los cuales, 11 tuvieron alteración en la RM (p = 0,04) y 10 afectación neurológica (p = 0,008). Tuvo una sensibilidad del 83,3%, IC 90%: 58-100 y una especificidad del 44,4%, IC 90%: 18,7-70,2 para la predicción de secuelas neurológicas. La RM estuvo alterada en 20/29 pacientes. Dieciséis de ellos tuvieron afectación neurológica (p < 0,001), teniendo una sensibilidad del 94%, IC 95%: 80-100 y una especificidad del 66,6%, IC 95%: 36-97,5 para la predicción de secuelas neurológicas. Una escala de Noyola et al. ≥ 2 se asoció a retraso psicomotor (p < 0,001). Conclusión: Nuestro trabajo valida los estudios previos en los que se encuentra correlación estadísticamente significativa entre la extensión de las lesiones en neuroimagen y la gravedad de los déficits neurológicos. (AU)

Background: Congenital cytomegalovirus (CMV) infection is an important cause of disability. There is little evidence on the prognostic value of lesions identified in neuroimaging studies. Aim: The study aimed to assess the severity of lesions detected with brain MRI and transfontanellar ultrasound and their relationship with long-term neurological deficits. Patients and methods: We performed a retrospective, analytical, observational study of 36 patients with congenital CMV infection. Neuroimaging studies were reviewed and classified according to the modified Noyola’ scale. Imaging findings were compared with neurological alterations in the patients’ most recent follow-up evaluation at the paediatric neurology department. Results: Thirty-six patients were studied (transfontanellar ultrasound: 30; brain MRI: 29). Twenty of 30 patients showed ultrasound abnormalities; of these, 11 showed alterations on brain MR images (P=.04) and 10 had neurological impairment (P=.008). Transfontanellar ultrasound had a sensitivity of 83.3%, 90% CI: 58-100 and a specificity of 44.4%, 90% CI: 18.7-70.2 for predicting neurological sequelae. Brain MRI displayed abnormalities in 20 of 29 patients, of whom 16 had neurological impairment (P<.001). MRI had a sensitivity of 94%, 95% CI: 80-100 and a specificity of 66.6%, 95% CI: 36-97.5 for predicting neurological sequelae. Modified Noyola’ scale values >2 were correlated with psychomotor retardation (P<.001). Conclusions: Our findings validate previous studies reporting a statistical significant correlation between the extension of neuroimaging lesions and severity of neurological deficits. (AU)

Efficacy and safety of benralizumab in chronic rhinosinusitis with nasal polyps: A randomized, placebo-controlled trial.

BACKGROUND: Eosinophilic inflammation has been implicated in the pathogenesis, severity, and treatment responsiveness of chronic rhinosinusitis with nasal polyps (CRSwNP). OBJECTIVE: We sought to assess the efficacy and safety of benralizumab-mediated eosinophil depletion for treating CRSwNP. METHODS: The phase 3 OSTRO study enrolled patients with severe CRSwNP who were symptomatic despite treatment with intranasal corticosteroids and who had a history of systemic corticosteroid (SCS) use and/or surgery for nasal polyps (NP). Patients were randomized 1:1 to treatment with benralizumab 30 mg or placebo every 4 weeks for the first 3 doses and every 8 weeks thereafter. Coprimary end points were change from baseline to week 40 in NP score (NPS) and patient-reported mean nasal blockage score reported once every 2 weeks. RESULTS: The study population comprised 413 randomized patients (207 in the benralizumab group and 206 in the placebo group). Benralizumab significantly improved NPS and nasal blockage score compared to placebo at week 40 (P ≤ .005). Improvements in Sinonasal Outcome Test 22 score at week 40, time to first NP surgery and/or SCS use for NP, and time to first NP surgery were not statistically significant between treatment groups. Nominal significance was obtained for improvement in difficulty in sense of smell score at week 40 (P = .003). Subgroup analyses suggested influences of comorbid asthma, number of NP surgeries, sex, body mass index, and baseline blood eosinophil count on treatment effects. Benralizumab was safe and well tolerated. CONCLUSION: Benralizumab, when added to standard-of-care therapy, reduced NPS, decreased nasal blockage, and reduced difficulty with sense of smell compared to placebo in patients with CRSwNP. TRIAL REGISTRATION: ClinicalTrials.gov NCT03401229.

Association between neuroimaging findings and neurological sequelae in patients with congenital cytomegalovirus infection.

BACKGROUND: Congenital cytomegalovirus (CMV) infection is an important cause of disability. There is little evidence on the prognostic value of lesions identified in neuroimaging studies. AIM: The study aimed to assess the severity of lesions detected with brain MRI and transfontanellar ultrasound and their relationship with long-term neurological deficits. PATIENTS AND METHODS: We performed a retrospective, analytical, observational study of 36 patients with congenital CMV infection. Neuroimaging studies were reviewed and classified according to the modified Noyola' scale. Imaging findings were compared with neurological alterations in the patients' most recent follow-up evaluation at the paediatric neurology department. RESULTS: Thirty-six patients were studied (transfontanellar ultrasound: 30; brain MRI: 29). Twenty of 30 patients showed ultrasound abnormalities; of these, 11 showed alterations on brain MR images (P = .04) and 10 had neurological impairment (P = .008). Transfontanellar ultrasound had a sensitivity of 83.3%, 90% CI: 58-100 and a specificity of 44.4%, 90% CI: 18.7-70.2 for predicting neurological sequelae. Brain MRI displayed abnormalities in 20 of 29 patients, of whom 16 had neurological impairment (P < .001). MRI had a sensitivity of 94%, 95% CI: 80-100 and a specificity of 66.6%, 95% CI: 36-97.5 for predicting neurological sequelae. Modified Noyola' scale values > 2 were correlated with psychomotor retardation (P < .001). CONCLUSIONS: Our findings validate previous studies reporting a statistical significant correlation between the extension of neuroimaging lesions and severity of neurological deficits.

The Effect of Radiation and Chemoradiation Therapy on the Head and Neck Mucosal Microbiome: A Review.

Radiation (RT) and chemoradiation therapy (CRT) play an essential role in head and neck cancer treatment. However, both cause numerous side effects in the oral cavity, paranasal sinuses, and pharynx, having deleterious consequences on patients' quality of life. Concomitant with significant advances in radiation oncology, much attention has turned to understanding the role of the microbiome in the pathogenesis of treatment-induced tissue toxicity, to ultimately explore microbiome manipulation as a therapeutic intervention. This review sought to discuss current publications investigating the impact of RT and CRT-induced changes on the head and neck microbiome, using culture-independent molecular methods, and propose opportunities for future directions. Based on 13 studies derived from a MEDLINE, EMBASE, and Web of Science search on November 7, 2021, use of molecular methods has uncovered various phyla and genera in the head and neck microbiome, particularly the oral microbiome, not previously known using culture-based methods. However, limited research has investigated the impact of RT/CRT on subsites other than the oral cavity and none of the studies aimed to examine the relationship between the head and neck microbiome and treatment effectiveness. Findings from this review provide helpful insights on our current understanding of treatment-induced oral mucositis, dental plaque, and caries formation and highlight the need for future research to examine the effect of RT/CRT on the sinonasal and oropharyngeal microbiome. In addition, future research should use larger cohorts, examine the impact of the microbiome on treatment response, and study the effect of manipulating the microbiome to overcome therapy resistance.

Micromechanical Compatibility between Cells and Scaffolds Directs the Phenotypic Transition of Stem Cells.

This study experimentally substantiates that the micromechanical compatibility between cell and substrate is essential for cells to achieve energetically favorable mechanotransduction that directs phenotypic transitions. The argument for this compatibility is based on a thermodynamic model that suggests that the response of cells to their substrate mechanical environment is a consequence of the interchange between forms of energy governing the cell-substrate interaction. Experimental validation for the model has been carried out by investigating the osteogenic differentiation of dental follicle stem cells (DFSCs) seeded on electrospun fibrous scaffolds. Electrospinning of blends containing polycaprolactone (PCL) and silk fibroin (SF) with varying composition of cellulose nanocrystals (CNCs) resulted in three-dimensional (3D) fibrous scaffolds with bimodal distribution of fiber diameter, which provides both macroscopically stiff and microscopically compliant scaffolds for cells without affecting the surface chemical functionality of scaffolds. Atomic force microscopy (AFM) with a colloidal probe and single-cell force spectroscopy were used to characterize cell stiffness and scaffold stiffness on the cellular level, as well as cell-scaffold adhesive interaction (chemical functionality). This study has successfully varied scaffold mechanical properties without affecting their surface chemistry. In vitro tests indicate that the micromechanical compatibility between cells and scaffolds has been significantly correlated with mechanosensitive gene expression markers and osteogenic differentiation markers of DFSCs. The agreement between experimental observations and the thermodynamic model affirms that the cellular response to the mechanical environment, though biological in nature, follows the laws of the energy interchange to achieve its self-regulating behavior. More importantly, this study provides systematic evidence, through extensive and rigorous experimental studies, for the first time that rationalizes that micromechanical compatibility is indeed important to the efficacy of regenerative medicine.

Smart Syringe Vending Machines: Research Capabilities and Implications for Research Data Collection.

OBJECTIVE: Syringe vending machines (SVMs) are intended to supplement the standard syringe exchange programs to access hard-to-reach groups and to cover unserved geographical areas. This report describes how we adapted SVMs to deliver interventions and collect research data as part of a study of smart SVMs (SSVMs) in Tbilisi, Georgia. METHOD: To create SSVMs, we upgraded commercial vending machines and developed a computer program to track and record interactions and to display messages related to study procedures. Preferred locations for SSVMs, product specifications, and the mode of operation were determined through formative input from people who inject drugs (PWID). SSVMs were installed near pharmacies and serve both the general population and PWID. The "hidden" interactive menu for the PWID prevention kits was displayed on the screen only when a special plastic card was used. The plastic cards were distributed to the clients of fixed syringe exchange programs and to their peers who were not in contact with harm-reduction services. RESULTS: Ten SSVMs were operational in Tbilisi as of March 2021, with more than 800 PWID using them on a regular basis. More than half of sterile equipment kits were distributed during weekends and night hours. CONCLUSIONS: Our innovative SSVM integrates features for intervention delivery and research data collection. It can be used for testing a variety of interventions beyond syringes (e.g., distribution of HIV/hepatitis C virus self-tests) and provides opportunities for serving various at-risk groups that might not otherwise access these products and services (e.g., men who have sex with men, commercial sex workers).

Thermal shrinkage reveals the feasibility of pulse-delay photocuring technique.

OBJECTIVES: To resolve the feasibility of the pulse-delay photocuring technique as a clinical strategy for reducing the detrimental polymerization stress induced in dental composites during the photocuring process. METHODS: Model dental composites with high and low-filler contents were cured with the pulse-delay photocuring technique using different combinations of photocuring variables (irradiance, exposure time, and delay time). Irradiance used ranged from 0.1W/cm2 to 4W/cm2. The exposure time of the first pulse varied from 0.2s to 27.2s and the delay times ranged from 10s to 120s. The radiant exposure was varied from 4J/cm2 to 20J/cm2. A cantilever-beam based instrument (NIST Standards Reference Instrument 6005) was used to implement the photocuring technique for the measurement of the polymerization properties (the degree of monomer conversion, polymerization stress induced due to shrinkage, and temperature change due to the reaction exotherm and curing light absorbance) simultaneously in real-time. These properties were compared with those obtained using the conventional photocuring technique (i.e., using a constant irradiance for a fixed exposure time, a uniform exposure). RESULTS: There exists a minimum radiant exposure, such that a reduction in the polymerization stress can be achieved without sacrificing the degree of monomer conversion by using the pulse-delay over the conventional photocuring technique. More specifically, stress reductions of up to 19% and 32% was observed with the pulse-delay when compared with the conventional photocuring technique at an irradiance of 0.5W/cm2 and 4W/cm2, respectively. The reduction occurred when the exposure time of the first pulse was greater than, but closer to, the gelation time (i.e., lower than the vitrification time) of the composite, regardless of the delay time used. Lower thermal shrinkage (contraction) during the post-curing time, rather than the stress relaxation during the delay time or lower degree of monomer conversion as claimed in the literature, is the cause of the reduction in the polymerization stress. SIGNIFICANCE: The study clarifies a long-standing confusion and controversy on the applicability of the pulse-delay photocuring technique for reducing the polymerization stress and promotes its potential clinical success for dental restorative composites.

Outbreak of Pseudomonas aeruginosa producing VIM carbapenemase in an intensive care unit and its termination by implementation of waterless patient care.

BACKGROUND: Long-term outbreaks of multidrug-resistant Gram-negative bacilli related to hospital-building water systems have been described. However, successful mitigation strategies have rarely been reported. In particular, environmental disinfection or replacement of contaminated equipment usually failed to eradicate environmental sources of Pseudomonas aeruginosa. METHODS: We report the investigation and termination of an outbreak of P. aeruginosa producing VIM carbapenemase (PA-VIM) in the adult intensive care unit (ICU) of a Swiss tertiary care hospital with active case finding, environmental sampling and whole genome sequencing (WGS) of patient and environmental strains. We also describe the implemented control strategies and their effectiveness on eradication of the environmental reservoir. RESULTS: Between April 2018 and September 2020, 21 patients became either infected or colonized with a PA-VIM strain. For 16 of them, an acquisition in the ICU was suspected. Among 131 environmental samples collected in the ICU, 13 grew PA-VIM in sink traps and drains. WGS confirmed the epidemiological link between clinical and environmental strains and the monoclonal pattern of the outbreak. After removing sinks from patient rooms and implementation of waterless patient care, no new acquisition was detected in the ICU within 8 months after the intervention. DISCUSSION: Implementation of waterless patient care with removal of the sinks in patient rooms was successful for termination of a PA-VIM ICU outbreak linked to multiple environmental water sources. WGS provides highly discriminatory accuracy to investigate environment-related outbreaks.

Community perspectives on supervised consumption sites: Insights from four U.S. counties deeply affected by opioids.

BACKGROUND: To address the overdose crisis in the United States, expert groups have been nearly unanimous in calls for increasing access to evidence-based treatment and overdose reversal drugs. In some places there have also been calls for implementing supervised consumption sites (SCSs). Some cities-primarily in coastal urban areas-have explored the feasibility and acceptability of introducing them. However, the perspectives of community stakeholders from more inland and rural areas that have also been hard hit by opioids are largely missing from the literature. METHODS: To examine community attitudes about implementing SCSs for people who use opioids (PWUO) in areas with acute opioid problems, the research team conducted in-depth interviews and focus groups in four counties: Ashtabula and Cuyahoga Counties in Ohio, and Carroll and Hillsborough Counties in New Hampshire, two states with high rates of opioid overdose. Participants were policy, treatment, and criminal justice professionals, frontline harm reduction and service providers, and PWUO. RESULTS: Key informants noted benefits to SCSs, but also perceived potential drawbacks such as that they may enable opioid use, and potential practical barriers, including lack of desire among PWUO to travel to an SCS after purchasing opioids and fear of arrest. Key informants generally believed their communities likely would not currently accept SCSs due to cultural, resource, and practical barriers. They viewed publication of evidence on SCSs and community education as essential for fostering acceptance. CONCLUSIONS: Despite cultural and other barriers, implementation of SCSs may be more feasible in urban communities with existing (and perhaps more long-standing) harm reduction programs, greater treatment resources, and adequate transportation, particularly if there is strong evidence to support them.

Renal Dnase1 expression is regulated by FGF23 but loss of Dnase1 does not alter renal phosphate handling.

Fibroblast growth factor 23 (FGF23) is a bone-derived endocrine hormone that regulates phosphate and vitamin D metabolism. In models of FGF23 excess, renal deoxyribonuclease 1 (Dnase1) mRNA expression is downregulated. Dnase-1 is an endonuclease which binds monomeric actin. We investigated whether FGF23 suppresses renal Dnase-1 expression to facilitate endocytic retrieval of renal sodium dependent phosphate co-transporters (NaPi-IIa/c) from the brush border membrane by promoting actin polymerization. We showed that wild type mice on low phosphate diet and Fgf23-/- mice with hyperphosphatemia have increased renal Dnase1 mRNA expression while in Hyp mice with FGF23 excess and hypophosphatemia, Dnase1 mRNA expression is decreased. Administration of FGF23 in wild type and Fgf23-/- mice lowered Dnase1 expression. Taken together, our data shows that Dnase1 is regulated by FGF23. In 6-week-old Dnase1-/- mice, plasma phosphate and renal NaPi-IIa protein were significantly lower compared to wild-type mice. However, these changes were transient, normalized by 12 weeks of age and had no impact on bone morphology. Adaptation to low and high phosphate diet were similar in Dnase1-/- and Dnase1+/+ mice, and loss of Dnase1 gene expression did not rescue hyperphosphatemia in Fgf23-/- mice. We conclude that Dnase-1 does not mediate FGF23-induced inhibition of renal tubular phosphate reabsorption.

Ataluren and aminoglycosides stimulate read-through of nonsense codons by orthogonal mechanisms.

During protein synthesis, nonsense mutations, resulting in premature stop codons (PSCs), produce truncated, inactive protein products. Such defective gene products give rise to many diseases, including cystic fibrosis, Duchenne muscular dystrophy (DMD), and some cancers. Small molecule nonsense suppressors, known as TRIDs (translational read-through-inducing drugs), stimulate stop codon read-through. The best characterized TRIDs are ataluren, which has been approved by the European Medicines Agency for the treatment of DMD, and G418, a structurally dissimilar aminoglycoside. Previously [1], we applied a highly purified in vitro eukaryotic translation system to demonstrate that both aminoglycosides like G418 and more hydrophobic molecules like ataluren stimulate read-through by direct interaction with the cell's protein synthesis machinery. Our results suggested that they might do so by different mechanisms. Here, we pursue this suggestion through a more-detailed investigation of ataluren and G418 effects on read-through. We find that ataluren stimulation of read-through derives exclusively from its ability to inhibit release factor activity. In contrast, G418 increases functional near-cognate tRNA mispairing with a PSC, resulting from binding to its tight site on the ribosome, with little if any effect on release factor activity. The low toxicity of ataluren suggests that development of new TRIDs exclusively directed toward inhibiting termination should be a priority in combatting PSC diseases. Our results also provide rate measurements of some of the elementary steps during the eukaryotic translation elongation cycle, allowing us to determine how these rates are modified when cognate tRNA is replaced by near-cognate tRNA ± TRIDs.