The mechanisms of integral membrane protein biogenesis.

Roughly one quarter of all genes code for integral membrane proteins that are inserted into the plasma membrane of prokaryotes or the endoplasmic reticulum membrane of eukaryotes. Multiple pathways are used for the targeting and insertion of membrane proteins on the basis of their topological and biophysical characteristics. Multipass membrane proteins span the membrane multiple times and face the additional challenges of intramembrane folding. In many cases, integral membrane proteins require assembly with other proteins to form multi-subunit membrane protein complexes. Recent biochemical and structural analyses have provided considerable clarity regarding the molecular basis of membrane protein targeting and insertion, with tantalizing new insights into the poorly understood processes of multipass membrane protein biogenesis and multi-subunit protein complex assembly.

Substrate-driven assembly of a translocon for multipass membrane proteins.

Most membrane proteins are synthesized on endoplasmic reticulum (ER)-bound ribosomes docked at the translocon, a heterogeneous ensemble of transmembrane factors operating on the nascent chain1,2. How the translocon coordinates the actions of these factors to accommodate its different substrates is not well understood. Here we define the composition, function and assembly of a translocon specialized for multipass membrane protein biogenesis3. This 'multipass translocon' is distinguished by three components that selectively bind the ribosome-Sec61 complex during multipass protein synthesis: the GET- and EMC-like (GEL), protein associated with translocon (PAT) and back of Sec61 (BOS) complexes. Analysis of insertion intermediates reveals how features of the nascent chain trigger multipass translocon assembly. Reconstitution studies demonstrate a role for multipass translocon components in protein topogenesis, and cells lacking these components show reduced multipass protein stability. These results establish the mechanism by which nascent multipass proteins selectively recruit the multipass translocon to facilitate their biogenesis. More broadly, they define the ER translocon as a dynamic assembly whose subunit composition adjusts co-translationally to accommodate the biosynthetic needs of its diverse range of substrates.

Mechanism of an intramembrane chaperone for multipass membrane proteins.

Multipass membrane proteins play numerous roles in biology and include receptors, transporters, ion channels and enzymes1,2. How multipass proteins are co-translationally inserted and folded at the endoplasmic reticulum is not well understood2. The prevailing model posits that each transmembrane domain (TMD) of a multipass protein successively passes into the lipid bilayer through a front-side lateral gate of the Sec61 protein translocation channel3-9. The PAT complex, an intramembrane chaperone comprising Asterix and CCDC47, engages early TMDs of multipass proteins to promote their biogenesis by an unknown mechanism10. Here, biochemical and structural analysis of intermediates during multipass protein biogenesis showed that the nascent chain is not engaged with Sec61, which is occluded and latched closed by CCDC47. Instead, Asterix binds to and redirects the substrate to a location behind Sec61, where the PAT complex contributes to a multipass translocon surrounding a semi-enclosed, lipid-filled cavity11. Detection of multiple TMDs in this cavity after their emergence from the ribosome suggests that multipass proteins insert and fold behind Sec61. Accordingly, biogenesis of several multipass proteins was unimpeded by inhibitors of the Sec61 lateral gate. These findings elucidate the mechanism of an intramembrane chaperone and suggest a new framework for multipass membrane protein biogenesis at the endoplasmic reticulum.

Lobar or Sublobar Resection for Peripheral Stage IA Non-Small-Cell Lung Cancer.

BACKGROUND: The increased detection of small-sized peripheral non-small-cell lung cancer (NSCLC) has renewed interest in sublobar resection in lieu of lobectomy. METHODS: We conducted a multicenter, noninferiority, phase 3 trial in which patients with NSCLC clinically staged as T1aN0 (tumor size, ≤2 cm) were randomly assigned to undergo sublobar resection or lobar resection after intraoperative confirmation of node-negative disease. The primary end point was disease-free survival, defined as the time between randomization and disease recurrence or death from any cause. Secondary end points were overall survival, locoregional and systemic recurrence, and pulmonary functions. RESULTS: From June 2007 through March 2017, a total of 697 patients were assigned to undergo sublobar resection (340 patients) or lobar resection (357 patients). After a median follow-up of 7 years, sublobar resection was noninferior to lobar resection for disease-free survival (hazard ratio for disease recurrence or death, 1.01; 90% confidence interval [CI], 0.83 to 1.24). In addition, overall survival after sublobar resection was similar to that after lobar resection (hazard ratio for death, 0.95; 95% CI, 0.72 to 1.26). The 5-year disease-free survival was 63.6% (95% CI, 57.9 to 68.8) after sublobar resection and 64.1% (95% CI, 58.5 to 69.0) after lobar resection. The 5-year overall survival was 80.3% (95% CI, 75.5 to 84.3) after sublobar resection and 78.9% (95% CI, 74.1 to 82.9) after lobar resection. No substantial difference was seen between the two groups in the incidence of locoregional or distant recurrence. At 6 months postoperatively, a between-group difference of 2 percentage points was measured in the median percentage of predicted forced expiratory volume in 1 second, favoring the sublobar-resection group. CONCLUSIONS: In patients with peripheral NSCLC with a tumor size of 2 cm or less and pathologically confirmed node-negative disease in the hilar and mediastinal lymph nodes, sublobar resection was not inferior to lobectomy with respect to disease-free survival. Overall survival was similar with the two procedures. (Funded by the National Cancer Institute and others; CALGB 140503 ClinicalTrials.gov number, NCT00499330.).

Msp1 Is a Membrane Protein Dislocase for Tail-Anchored Proteins.

Mislocalized tail-anchored (TA) proteins of the outer mitochondrial membrane are cleared by a newly identified quality control pathway involving the conserved eukaryotic protein Msp1 (ATAD1 in humans). Msp1 is a transmembrane AAA-ATPase, but its role in TA protein clearance is not known. Here, using purified components reconstituted into proteoliposomes, we show that Msp1 is both necessary and sufficient to drive the ATP-dependent extraction of TA proteins from the membrane. A crystal structure of the Msp1 cytosolic region modeled into a ring hexamer suggests that active Msp1 contains a conserved membrane-facing surface adjacent to a central pore. Structure-guided mutagenesis of the pore residues shows that they are critical for TA protein extraction in vitro and for functional complementation of an msp1 deletion in yeast. Together, these data provide a molecular framework for Msp1-dependent extraction of mislocalized TA proteins from the outer mitochondrial membrane.

The COMPARE head-to-head, randomized controlled trial of SEL-212 (pegadricase plus rapamycin-containing nanoparticle, ImmTOR™) versus pegloticase for refractory gout.

OBJECTIVES: Serum urate (SU) lowering with PEGylated uricases in gout can reduce flares and tophi. However, treatment-emergent anti-drug antibodies adversely affect safety and efficacy and the currently approved PEGylated uricase pegloticase requires twice-monthly infusions. Investigational SEL-212 therapy aims to promote uricase-specific tolerance via monthly sequential infusions of a proprietary rapamycin-containing nanoparticle (ImmTOR) and pegadricase. METHODS: COMPARE was a randomized, phase 2, open-label trial of SEL-212 vs pegloticase in adults with refractory gout. SEL-212 [ImmTOR (0.15 mg/kg) and pegadricase (0.2 mg/kg)] was infused monthly or pegloticase (8 mg) twice monthly for 6 months. The primary endpoint was the proportion of participants with SU <6 mg/dl for ≥80% of the time during 3 and 6 months. Secondary outcomes were mean SU, gout flares, number of tender and/or swollen joints and safety. RESULTS: During months 3 and 6 combined, numerically more participants achieved and maintained a SU <6 mg/dl for ≥80% of the time with SEL-212 vs pegloticase (53.0% vs 46.0%, P = 0.181). The percentage reductions in SU levels were statistically greater during months 3 and 6 with SEL-212 vs pegloticase (-73.79% and -47.96%, P = 0.0161). Reductions in gout flare incidence and number of tender and/or swollen joints were comparable between treatments. There were numerical differences between the most common treatment-related adverse events of interest with SEL-212 and pegloticase: gout flares (60.2% vs 50.6%), infections (25.3% vs 18.4%) and infusion-related reactions (15.7% vs 11.5%), respectively. Stomatitis (and related terms) was experienced by eight participants (9.6%) with SEL-212 and none with pegloticase. Stomatitis, a known event for rapamycin, was associated with ImmTOR only. CONCLUSIONS: SEL-212 efficacy and tolerability were comparable to pegloticase in refractory gout. This was associated with a substantial reduction in treatment burden with SEL-212 due to decreased infusion frequency vs pegloticase. CLINICAL TRIAL REGISTRATION: NCT03905512.

Lean body mass in living kidney donors impacts postoperative renal function.

PURPOSE: A living donor kidney transplant is the optimal treatment for chronic renal impairment. Our objective is to assess if lean skeletal muscle mass and donor factors such as body mass index, hypertension, and age impact on renal function following donor nephrectomy. METHODS: Potential donors undergo CT angiography as part of their work-up in our institution. Using dedicated software (Horos®), standardized skeletal muscle area measured at the L3 vertebrae was calculated. When corrected for height, skeletal muscle index can be derived. Skeletal muscle mass index below predefined levels was classified as sarcopenic. The correlation of CT-derived skeletal muscle index and postoperative renal function at 12 months was assessed. Co-variables including donor gender, age, body mass index (BMI), and presence of pre-op hypertension were also assessed for their impact on postoperative renal function. RESULTS: 275 patients who underwent living donor nephrectomy over 10 years were included. Baseline pre-donation glomerular filtration rate (GFR) and renal function at one year post-op were similar between genders. 29% (n = 82) of patients met the criteria for CT-derived sarcopenia. Sarcopenic patients were more likely to have a higher GFR at one year post-op (69.3 vs 63.9 mL/min/1.73 m2, p < 0.001). The main factors impacting better renal function at one year were the presence of sarcopenia and younger age at donation. CONCLUSION: When selecting donors, this study highlights that patients with low skeletal mass are unlikely to underperform in terms of recovery of their renal function postoperatively at one year when compared to patients with normal muscle mass and should not be a barrier to kidney donation.

Ubiquilins Chaperone and Triage Mitochondrial Membrane Proteins for Degradation.

We investigated how mitochondrial membrane proteins remain soluble in the cytosol until their delivery to mitochondria or degradation at the proteasome. We show that Ubiquilin family proteins bind transmembrane domains in the cytosol to prevent aggregation and temporarily allow opportunities for membrane targeting. Over time, Ubiquilins recruit an E3 ligase to ubiquitinate bound clients. The attached ubiquitin engages Ubiquilin's UBA domain, normally bound to an intramolecular UBL domain, and stabilizes the Ubiquilin-client complex. This conformational change precludes additional chances at membrane targeting for the client, while simultaneously freeing Ubiquilin's UBL domain for targeting to the proteasome. Loss of Ubiquilins by genetic ablation or sequestration in polyglutamine aggregates leads to accumulation of non-inserted mitochondrial membrane protein precursors. These findings define Ubiquilins as a family of chaperones for cytosolically exposed transmembrane domains and explain how they use ubiquitin to triage clients for degradation via coordinated intra- and intermolecular interactions.

A Prospective Multi-institutional Study Using a Novel Safety Valve for the Prevention of Catheter Balloon Inflation Injury of the Urethra.

PURPOSE: We prospectively assessed the ability of a novel transurethral catheterization safety valve to prevent urethral catheter balloon injury in a multi-institutional clinical setting. MATERIALS AND METHODS: A prospective, multi-institution study was conducted. The safety valve was introduced for urinary catheterization in 6 hospital groups (4 in Ireland; 2 in the UK). The safety valve allows fluid in the catheter system to vent through a pressure relief valve if attempted intraurethral inflation of the catheter's anchoring balloon occurs. Device usage was studied over a 12-month period, with data recorded using a 7-item data sticker containing a scannable QR code. "Venting" through the safety valve during catheterization was indicative of prevention of a urethral injury. An embedded 3-month study was conducted in 3 centers, with any catheter balloon injuries occurring during catheterization without safety valve use referred to the on-call urology team recorded. Health economic analyses were also performed. RESULTS: During the overall 12-month device study phase, 994 urethral catheterizations were performed across study sites. Twenty-two (2.2%) episodes of safety valve venting were recorded. No urethral injuries occurred in these patients. In the embedded 3-month study, 18 catheter balloon injuries were recorded in association with catheterizations performed without the safety valve. Based on confirmed and device-prevented urethral injuries, the injury rate for urethral catheterization without safety valve use was calculated to be 5.5/1,000 catheterizations. CONCLUSIONS: The safety valve has the potential to eliminate catheter balloon injury if widely adopted. It represents a simple, effective, and innovative solution to this recurring problem applicable to all patient cohorts.

Tail-anchored membrane protein insertion into the endoplasmic reticulum.

Membrane proteins are inserted into the endoplasmic reticulum (ER) by two highly conserved parallel pathways. The well-studied co-translational pathway uses signal recognition particle (SRP) and its receptor for targeting and the SEC61 translocon for membrane integration. A recently discovered post-translational pathway uses an entirely different set of factors involving transmembrane domain (TMD)-selective cytosolic chaperones and an accompanying receptor at the ER. Elucidation of the structural and mechanistic basis of this post-translational membrane protein insertion pathway highlights general principles shared between the two pathways and key distinctions unique to each.

Pegloticase causes prolonged improvement in multiple disease parameters in patients with chronic refractory gout who maintain low serum urate levels.

OBJECTIVES: To assess the benefit of long-term urate-lowering with pegloticase. METHODS: The results from two, 6-month, randomised controlled trials (RCTs) and their 30-month open-label extension (OLE) were analysed. Efficacy was assessed in urate responders (patients with plasma urate <6.0 mg/dL for ≥80% of assessments around the 3- and 6-month time periods) to the approved regimen (8 mg every 2 weeks [q2w]) and responders to q4w treatment. Assessments included serum urate (sU), Patient Global Assessment (PtGA), tender and swollen joints (TJC and SJC), pain, Health Assessment Questionnaire Disability Index, bodily pain, the Arthritis-Specific Health Index, and reduction of target tophi. RESULTS: 34 responders to pegloticase in the RCTs were followed throughout the 2.5 years of the OLE. Of these, 20 received 8 mg pegloticase q2w and 14 q4w. The results for patients who received pegloticase q2w indicated significant improvements between RCT baseline and the final OLE evaluation for sU (p<0.0001), PtGA (p<0.0001), TJC (p=0.0001), and SJC (p=0.0014); 61.5%, had complete target tophus resolution. The results for patients treated monthly indicated significant improvements between RCT baseline and the final OLE evaluation for sU (p<0.001), PGA (p=0.0003), TJC (p=0.008), and SJC (p<0.0001);100% had complete target tophus resolution. CONCLUSIONS: There were significant sustained clinical benefits with long-term pegloticase treatment in patients with chronic refractory gout achieving a urate-lowering effect during the first 6 months of therapy and followed for up to 30 additional months.

Expert Opinion on Pegloticase with Concomitant Immunomodulatory Therapy in the Treatment of Uncontrolled Gout to Improve Efficacy, Safety, and Durability of Response.

PURPOSE OF REVIEW: Gout is a systemic disease from which some patients develop numerous painful tophi that adversely affect quality of life and functionality. Some patients treated with oral urate-lowering therapy are unable to maintain serum urate levels below 6 mg/dL, and these patients, thus classified as having refractory or uncontrolled gout, often require therapy with pegloticase to reduce symptoms and tophaceous burden. The objective of this expert opinion review is to summarize the available evidence supporting the use of concomitant immunomodulators with pegloticase to prevent development of anti-drug antibodies (ADAs) when treating patients with uncontrolled gout. RECENT FINDINGS: Emerging evidence suggests that adding an immunomodulator to pegloticase therapy can substantially increase response rates to double those observed in phase 3 randomized controlled trials. The combination of immunomodulation with pegloticase should be considered in routine clinical practice to improve durability of response, efficacy, and safety among patients with uncontrolled gout who otherwise have limited therapeutic options.

eConsults' Impact on Care Access and Wait Times in Rheumatology.

BACKGROUND/OBJECTIVE: A growing number of health systems have implemented eConsults to improve access to specialty advice, but few studies have described their use in rheumatology or impact on visit wait times. We evaluated the uptake of an eConsult program and its impact on wait times for in-person rheumatology visits. METHODS: In this quality improvement project, we analyzed electronic health record data from 4 intervention clinics and 4 comparison clinics, 12 months before and after implementation of an eConsult program. We compared median wait time for rheumatology appointments using a pre-post difference-in-differences analysis and quantile regression, adjusting for patient age, race, sex, clinic pair, and primary insurance payer. We also interviewed 11 primary care providers from the intervention clinics and conducted a rheumatology provider focus group (n = 4) to elucidate experiences with the program. RESULTS: Rheumatologists recommended management in primary care or referral to another specialty for 41% of eConsults, reducing initial demand for in-person visits. The median wait times dropped in the intervention and the comparison clinics (42 and 25 days, respectively). Intervention clinic median wait time dropped 17 days more than comparison clinics, and this was nonstatistically significant (p = 0.089). eConsults fit provider care tasks best for triage or initial workup for diagnosis, and less well when tests required interpretation, or when back and forth communication was needed to manage the patient's condition. CONCLUSIONS: Implementation of eConsults for rheumatology was associated with reduced wait times for rheumatology appointments and supported primary care providers in the triage and workup for a substantial portion of patients.

Time to disease recurrence in noninfectious uveitis following long-acting injectable fluocinolone acetonide implant.

PURPOSE: To determine the time to disease recurrence with long-acting injectable fluocinolone acetonide implant (FAi) for noninfectious intermediate, posterior, and panuveitis. METHODS: This was a retrospective study of patients with at least 12 months of follow-up who had completed a 2-year prospective, investigational new drug study with 0.18-mg FAi. Time to uveitis recurrence or cystoid macular edema (CME) occurrence was recorded. RESULTS: Twelve eyes from 12 participants (mean age 43 years, range 25-64 years) were included. Patients were followed for a mean of 34.2 months (range, 12.0-56.9 months) after completion of the prospective trial. Five eyes (42%) did not have a documented uveitis recurrence or CME occurrence. Five eyes (42%) had a uveitis recurrence with the mean time to recurrence 36.1 months (range, 22.8-61.1 months) after FAi implantation. Two eyes (16%) had CME alone, the mean time to occurrence 36.9 months (range 36.1-42.1 months). On Kaplan-Meier analysis, the estimated probability of remaining recurrence-free 36 months after FAi implantation was 0.67 (95% confidence interval, 0.34-0.86). CONCLUSIONS: Data of study participants after completing a clinical trial suggest that the injectable FAi for noninfectious uveitis can provide control for 3 years on average. These long-term data support the use of FAi to control noninfectious uveitis.

PERIVASCULAR THICKENING ON OPTICAL COHERENCE TOMOGRAPHY AS A MARKER OF INFLAMMATION IN BIRDSHOT RETINOCHOROIDITIS.

PURPOSE: In this study, we hypothesized that thickening along the major arcade vessels is a noninvasive marker of inflammation in eyes with birdshot retinochoroiditis (BRC). METHODS: In this single-center retrospective study, patients with BRC were identified. Perivascular thickening was categorized as mild, moderate, or severe, based on a set of standard reference retinal thickness maps derived from representative spectral domain optical coherence tomography volume scans. The assigned perivascular severity thickness category was then compared with other inflammatory markers and optical coherence tomography measurements. These parameters were also examined in eyes with intermediate uveitis to assess the diagnostic specificity of perivascular thickening. RESULTS: In eyes with BRC, greater perivascular thickening was associated with increased vitreous haze (P = 0.009) and retinal vascular leakage on fluorescein angiography (P = 0.0001). Perivascular thickening was correlated with central subfield thickness and total macular volume on optical coherence tomography. Controlling for central subfield thickness and total macular volume, the odds of higher severity level of perivascular thickening were nine times greater in eyes with BRC than those with intermediate uveitis (P < 0.0001). Eyes with BRC and active inflammation were more likely to have moderate or severe perivascular thickening (P = 0.02). CONCLUSION: Perivascular thickening, determined by optical coherence tomography, may be a useful noninvasive biomarker of inflammation in eyes with BRC.

Colorectal Cancer Among Gout Patients Undergoing Colonoscopy.

BACKGROUND/OBJECTIVE: The connection between gout and various cancers remains unclear. We assessed the relationship between gout and colorectal cancer in a population of veterans. METHODS: We reviewed the Computerized Patient Record System of the VA New York Harbor Health Care System to assess the 10-year occurrence of colorectal cancer in patients with gout undergoing colonoscopy, versus patients with osteoarthritis but no gout. RESULTS: Gout and osteoarthritis subjects were similar in age, ethnicity, body mass index, and smoking history. Among 581 gout and 598 osteoarthritis subjects with documented colonoscopies, the 10-year prevalence of colorectal cancer was significantly lower in gout (0.8%) versus osteoarthritis (3.7%) (p = 0.0008) patients. Differences in colorectal cancer rates remained significant after stratifying for nonsteroidal anti-inflammatory drug use. Among gout subjects, use of colchicine and/or allopurinol, as well as the presence/absence of concomitant osteoarthritis, did not influence colorectal cancer occurrence. On subanalysis, differences in colorectal cancer occurrence between gout and osteoarthritis subjects persisted among those who underwent diagnostic (0.5% in gout vs 4.6% in osteoarthritis subjects, p < 0.001) but not screening (0.9% in gout subjects vs 1% in osteoarthritis subjects, p = 1.0) colonoscopy. There was no significant difference in nonmalignant colorectal polyp occurrence between gout and osteoarthritis subjects. CONCLUSIONS: Subjects with gout had decreased colonoscopy-documented occurrence of colorectal cancer compared with osteoarthritis subjects, suggesting a possible protective effect.

A dual fluorescent reporter for the investigation of methionine mistranslation in live cells.

In mammalian cells under oxidative stress, the methionyl-tRNA synthetase (MetRS) misacylates noncognate tRNAs at frequencies as high as 10% distributed among up to 28 tRNA species. Instead of being detrimental for the cell, misincorporation of methionine residues in the proteome reduces the risk of oxidative damage to proteins, which aids the oxidative stress response. tRNA microarrays have been essential for the detection of the full pattern of misacylated tRNAs, but have limited capacity to investigate the misacylation and mistranslation mechanisms in live cells. Here we develop a dual-fluorescence reporter to specifically measure methionine misincorporation at glutamic acid codons GAA and GAG via tRNA(Glu) mismethionylation in human cells. Our method relies on mutating a specific Met codon in the active site of the fluorescent protein mCherry to a Glu codon that renders mCherry nonfluorescent when translation follows the genetic code. Mistranslation utilizing mismethionylated tRNA(Glu) restores fluorescence in proportion to the amount of misacylated tRNA(Glu). This cellular approach works well for both transient transfection and established stable HEK293 lines. It is rapid, straightforward, and well suited for high-throughput activity analysis under a wide range of physiological conditions. As a proof of concept, we apply this method to characterize the effect of human tRNA(Glu) isodecoders on mistranslation and discuss the implications of our findings.

The GET System Inserts the Tail-Anchored Protein, SYP72, into Endoplasmic Reticulum Membranes.

The Arabidopsis (Arabidopsis thaliana) genome encodes homologs of the Guided Entry of Tail (GET)-anchored protein system for the posttranslational insertion of tail-anchored (TA) proteins into endoplasmic reticulum (ER) membranes. In yeast, TA proteins are loaded onto the cytosolic targeting factor Get3 and are then delivered to the membrane-associated Get1/2 complex for insertion into ER membranes. The role of the GET system in Arabidopsis was investigated by monitoring the membrane insertion of a tail-anchored protein, SYP72, a syntaxin. SYP72 bound to yeast Get3 in vitro, forming a Get3-SYP72 fusion complex that could be inserted into yeast GET1/2-containing proteoliposomes. The Arabidopsis GET system functioned in vivo to insert TA proteins into ER membranes as demonstrated by the fact that the YFP-tagged SYP72 localized to the ER in wild-type plants but accumulated as cytoplasmic inclusions in get1, get3, or get4 mutants. The GET mutants get1 and get3 were less tolerant of ER stress agents and showed symptoms of ER stress even under unstressed conditions. Hence, the GET system is responsible for the insertion of TA proteins into the ER in Arabidopsis, and mutants with GET dysfunctions are more susceptible to ER stress.

Parental awareness of testicular torsion amongst Irish parents.

PURPOSE: Testicular torsion is the most concerning underlying cause of acute scrotal pain that can lead to loss of the affected testicle. Whether a torted testicle can be salvaged surgically is directly affected by prompt presentation and diagnosis. This study aims to evaluate the awareness of testicular torsion amongst Irish parents and evaluate their response to a potential torsion. METHODS: An anonymous questionnaire was distributed to parents attending general paediatric clinics and an acute paediatric unit in two paediatric tertiary referral centres. SPSS statistical analysis software was used to perform multivariant analysis of the data. RESULTS: There were 242 completed surveys. Fifty-six percent of responders had an awareness of torsion. In the event of an episode of severe testicular pain parents who were aware of testicular torsion were 4 times more likely to present immediately than those who had no awareness of torsion (OR 4.2, 95% CI 1.4-12.2, P < 0.01), and those who identified correctly the critical timeframe were 3 times more likely to present immediately than those who did not (OR 3.0, 95% CI 0.85-10.8, P = 0.08). Of those parents with boys only 11% had discussed what to do in the event of acute scrotal pain. CONCLUSIONS: Education of this topic to the general Irish population and in particular to parents and young males is not established. Both knowledge of testicular torsion and awareness of the urgency in presentation are factors that determine parents promptness in seeking medical attention for their child in the setting of acute scrotal pain.