Tuberous Sclerosis: A Rare Disease with an Orphan Complex.

Introduction In the Republic of Ireland, there are no tuberous sclerosis complex (TSC) specialist clinics. Methods A clinical audit was carried out to assess the care received by patients attending two specialist adult epilepsy specialist centres, measuring their care against the UK guidelines. Results Although many baseline investigations are carried out, only one-third of patients had diagnostic genetic testing results available. Neuropsychiatry is largely neglected, and the completion of neuropsychiatric assessments checklists is inadequate. Discussions concerning SUDEP are not happening and access to treatment is limited. Reporting of radiological findings in TSC is inconsistent and the number of adults with TSC accessing specialist epilepsy services appear to be low. Discussion TSC care in the Republic of Ireland is fragmented, difficult to navigate and wasteful of resources due to the complex nature of the disease and no formal clinical setting to manage it. The service gaps echo the demand for an improved care system including consistent radiological reporting of TSC pathology. The absence of a specialist TSC clinic compounds the complexity of navigating care for individuals with TSC, families and healthcare professionals. Extending this audit nationally will give a more complete picture and highlight the resources required to bring care of these patients in line with recommended guidelines.

Multidisciplinary guidance for safe tracheostomy care during the COVID-19 pandemic: the NHS National Patient Safety Improvement Programme (NatPatSIP).

The COVID-19 pandemic is causing a significant increase in the number of patients requiring relatively prolonged invasive mechanical ventilation and an associated surge in patients who need a tracheostomy to facilitate weaning from respiratory support. In parallel, there has been a global increase in guidance from professional bodies representing staff who care for patients with tracheostomies at different points in their acute hospital journey, rehabilitation and recovery. Of concern are the risks to healthcare staff of infection arising from tracheostomy insertion and caring for patients with a tracheostomy. Hospitals are also facing extraordinary demands on critical care services such that many patients who require a tracheostomy will be managed outside established intensive care or head and neck units and cared for by staff with little tracheostomy experience. These concerns led NHS England and NHS Improvement to expedite the National Patient Safety Improvement Programme's 'Safe Tracheostomy Care' workstream as part of the NHS COVID-19 response. Supporting this workstream, UK stakeholder organisations involved in tracheostomy care were invited to develop consensus guidance based on: expert opinion; the best available published literature; and existing multidisciplinary guidelines. Topics with direct relevance for frontline staff were identified. This consensus guidance includes: infectivity of patients with respect to tracheostomy indications and timing; aerosol-generating procedures and risks to staff; insertion procedures; and management following tracheostomy.

Establishing a baseline for a national paediatric antimicrobial stewardship programme.

BACKGROUND: The majority of antimicrobial stewardship programmes focus on prescribing in adult populations; however, there is a recognized need for targeted paediatric antimicrobial stewardship to improve the quality and safety of prescribing amongst this patient group. OBJECTIVES: To describe the current epidemiology of antimicrobial prescribing in paediatric inpatient populations in Scotland to establish a baseline of evidence and identify priority areas for quality improvement to support a national paediatric antimicrobial stewardship programme. METHODS: A total of 559 paediatric inpatients were surveyed during the Scottish national point prevalence survey of healthcare-associated infections and antimicrobial prescribing, 2016. The prevalence of antimicrobial prescribing was calculated and characteristics of antimicrobial prescribing were described as proportions and compared between specialist hospitals and paediatric wards in acute hospitals. RESULTS: Prevalence of antimicrobial use in paediatric inpatients was 35.4% (95% CI = 31.6%-39.4%). Treatment of community- and hospital-acquired infections accounted for 47.1% and 20.7% of antimicrobial use, respectively, with clinical sepsis being the most common diagnosis and gentamicin the most frequently prescribed antimicrobial for the treatment of infection. The reason for prescribing was documented in the notes for 86.5% of all prescriptions and, of those assessed for compliance against local policy, 92.9% were considered compliant. CONCLUSIONS: Data from national prevalence surveys are advantageous when developing antimicrobial stewardship programmes. Results have highlighted differences in the prescribing landscape between paediatric inpatient populations in specialist hospitals and acute hospitals, and have informed priorities for the national antimicrobial stewardship programme, which reinforces the need for a targeted paediatric antimicrobial stewardship programme.

Multidisciplinary guidelines for the management of paediatric tracheostomy emergencies.

Temporary and permanent tracheostomies are required in children to manage actual or anticipated long-term ventilatory support, to aid secretion management or to manage fixed upper airway obstruction. Tracheostomies may be required from the first few moments of life, with the majority performed in children < 4 years of age. Although similarities with adult tracheostomies are apparent, there are key differences when managing the routine and emergency care of children with tracheostomies. The National Tracheostomy Safety Project identified the need for structured guidelines to aid multidisciplinary clinical decision making during paediatric tracheostomy emergencies. These guidelines describe the development of a bespoke emergency management algorithm and supporting resources. Our aim is to reduce the frequency, nature and severity of paediatric tracheostomy emergencies through preparation and education of staff, parents, carers and patients.

Two-dimensional knee valgus displacement as a predictor of patellofemoral pain in adolescent females.

Patellofemoral pain (PFP) is a prevalent lower limb musculo-skeletal injury in adolescent females. Female athletes with PFP display increased frontal plane knee joint motion in comparison to control subjects. The current investigation aimed to determine prospectively whether two-dimensional knee valgus displacement during landing could predict the risk of developing PFP. Seventy-six injury-free adolescent female athletes (age = 12.9 ±0.35 years) participated. At baseline participants performed three drop vertical jump trials from a 31-cm box. A standard video camera was used to record frontal plane knee joint kinematics. Over the 24-month follow-up, eight participants developed PFP, as diagnosed by a Chartered Physiotherapist. Knee valgus displacement was significantly increased in those who developed PFP compared to those who did not (mean difference = 7.79°; P = 0.002; partial eta squared = 0.07). Knee valgus displacement ≥10.6° predicted PFP with a sensitivity of 0.75 and specificity of 0.85. The associated positive likelihood ratio was 5. These results have clinical utility suggesting that two-dimensional analysis could be implemented to screen for increased risk of PFP in adolescent female athletes.

Gait Biomechanics in Participants, Six Months after First-time Lateral Ankle Sprain.

No research currently exists predicating a link between the injury-affiliated sensorimotor deficits of acute ankle sprain and those of chronic ankle instability during gait. This analysis evaluates participants with a 6-month history of ankle sprain injury to affirm this link. 69 participants with a 6-month history of acute first-time lateral ankle sprain were divided into subgroups ('chronic ankle instability' and 'coper') based on their self-reported disability and compared to 20 non-injured participants during a gait task. Lower extremity kinematic and kinetic data were collected from 200 ms pre- to 200 ms post-heel strike (period 1) and from 200 ms pre- to 200 ms post-toe off (period 2). The 'chronic ankle instability' subgroup (who reported greater disability) displayed increased knee flexion during period 1. During period 2, this subgroup exhibited greater total displacement at their ankle joint and greater extensor dominance at their knee. That many of these features are present, both in individuals with acute ankle sprain and those with chronic ankle instability may advocate a link between acute deficits and long-term outcome. Clinicians must be aware that the sensorimotor deficits of ankle sprain may persevere beyond the acute stage of injury and be cognizant of the capacity for impairments to pervade proximally.

Increased thrombin generation potential in symptomatic versus asymptomatic moderate or severe carotid stenosis and relationship with cerebral microemboli.

INTRODUCTION: The importance of thrombin generation in the pathogenesis of TIA or stroke and its relationship with cerebral microembolic signals (MES) in asymptomatic and symptomatic carotid stenosis has not been comprehensively assessed. METHODS: Plasma thrombin generation parameters from patients with moderate or severe (≥ 50%) asymptomatic carotid stenosis were compared with those from patients with symptomatic carotid stenosis in the early (≤ 4 weeks) and late phases (≥ 3 months) after TIA or stroke in this prospective, pilot observational study. Thrombin generation profile was longitudinally assessed in symptomatic patients with data at each time point. Bilateral transcranial Doppler ultrasound monitoring of the middle cerebral arteries was performed whenever possible to classify patients as MES-positive or MES-negative. RESULTS: Data from 31 asymptomatic, 46 'early symptomatic' and 35 'late symptomatic' patients were analysed. Peak thrombin (344.2 nM vs 305.3 nM; p = 0.01) and endogenous thrombin potential (1772.4 vs 1589.7; p = 0.047) were higher in early symptomatic than asymptomatic patients. Peak thrombin production decreased in symptomatic patients followed up from the early to late phase after TIA or stroke (339.7 nM vs 308.6 nM; p = 0.02). Transcranial Doppler ultrasound data were available in 25 asymptomatic, 31 early symptomatic and 27 late symptomatic patients. Early symptomatic MES-positive patients had a shorter 'time-to-peak thrombin' than asymptomatic MES-positive patients (p=0.04), suggesting a more procoagulant state in this early symptomatic subgroup. DISCUSSION: Thrombin generation potential is greater in patients with recently symptomatic than asymptomatic carotid stenosis, and decreases over time following TIA or stroke associated with carotid stenosis. These data improve our understanding of the haemostatic/thrombotic biomarker profile in moderate-severe carotid stenosis.

Single-leg drop landing movement strategies 6 months following first-time acute lateral ankle sprain injury.

No research exists predicating a link between acute ankle sprain injury-affiliated movement patterns and those of chronic ankle instability (CAI) populations. The aim of the current study was to perform a biomechanical analysis of participants, 6 months after they sustained a first-time acute lateral ankle sprain (LAS) injury to establish this link. Fifty-seven participants with a 6-month history of first-time LAS and 20 noninjured participants completed a single-leg drop landing task on both limbs. Three-dimensional kinematic (angular displacement) and sagittal plane kinetic (moment of force) data were acquired for the joints of the lower extremity, from 200 ms pre-initial contact (IC) to 200 ms post-IC. Individual joint stiffnesses and the peak magnitude of the vertical component of the ground reaction force (GRF) were also computed. LAS participants displayed increases in hip flexion and ankle inversion on their injured limb (P < 0.05); this coincided with a reduction in the net flexion-extension moment at the hip joint, with an increase in its stiffness (P < 0.05). There was no difference in the magnitude of the peak vertical GRF for either limb compared with controls. These results demonstrate that altered movement strategies persist in participants, 6 months following acute LAS, which may precipitate the onset of CAI.

Single-leg drop landing motor control strategies following acute ankle sprain injury.

No research currently exists investigating the effect of acute injury on single-limb landing strategies. The aim of the current study was to analyze the coordination strategies of participants in the acute phase of lateral ankle sprain (LAS) injury. Thirty-seven participants with acute, first-time LAS and 19 uninjured participants completed a single-leg drop landing task on both limbs. Three-dimensional kinematic (angular displacement) and sagittal plane kinetic (moment-of-force) data were acquired for the joints of the lower extremity from 200 ms pre-initial contact (IC) to 200 ms post-IC. The peak magnitude of the vertical component of the ground reaction force (GRF) was also computed. Injured participants displayed a bilateral increase in hip flexion, with altered transverse plane kinematic profiles at the knee and ankle for both limbs (P < 0.05). This coincided with a reduction in the net-supporting flexor moment of the lower extremity (P < 0.05) and magnitude of the peak vertical GRF for the injured limb (21.82 ± 2.44 N/kg vs 24.09 ± 2.77 N/kg; P = 0.013) in injured participants compared to control participants. These results demonstrate that compensatory movement strategies are utilized by participants with acute LAS to successfully reduce the impact forces of landing.

SCN1A variations and response to multiple antiepileptic drugs.

In the current study, we have used the haplotype-tagging single-nucleotide polymorphisms (SNPs) to determine associations between genetic variants in SCN1A and treatment response in 519 Caucasian patients with known response status for epilepsy treated with antiepileptic drugs (AEDs) with sodium channel blocking effects. Nine SNPs within SCN1A were genotyped in this cohort. The only association observed was for rs10188577. A greater proportion of drug-resistant patients were heterozygous compared with drug responsive patients (48.3% vs 35.4%, P=0.014). After correction for potential confounding factors, the association for rs10188577 was only marginally significant (P=0.049). In light of our findings, it seems unlikely that rs10188577 could be a major determinant of response to AEDs. However, looking at the influence of rs10188577 on the expressed quantitative trait association patterns within the immediate vicinity of SCN1A, we found significant associations with neighbouring sodium channel genes, SCN7A and SCN9A (P<0.025), which warrants further studies.

Pharmacogenomics of NAT2 and ABCG2 influence the toxicity and efficacy of sulphasalazine containing DMARD regimens in early rheumatoid arthritis.

Sulphasalazine (SSA) is a disease modifying anti-rheumatic drug (DMARD) that is commonly used to treat rheumatoid arthritis (RA). Plasma levels of SSA and its metabolite sulphapyridine are influenced by common polymorphisms in genes that encode N-acetyl transferase 2 (NAT2) and ATP-binding cassette protein G2 (ABCG2). Study participants had early RA that was treated with a combination DMARD regimen that included SSA. Toxicity was defined by cessation of SSA due to adverse effects and response as remission after 12 months of treatment. The effect of variables on toxicity was assessed by a Cox-proportional Hazard model and response by logistic regression. After correction for conventional variables, toxicity in 229 participants was influenced by NAT2 phenotype (hazard ratio=1.74 (95% confidence interval (CI) 1.01-3.21), P=0.044) and remission in 141 participants was associated with ABCG2 genotype (odds ratio=3.34 (95% CI 1.18-9.50), P=0.024). In our sample of early RA patients who were primarily treated with a combination of DMARDs, common variants in genes that encode NAT2 and ABCG2 were associated respectively with toxicity and response to SSA.

Tuberous sclerosis complex without tubers and subependymal nodules: a phenotype-genotype study.

Tuberous sclerosis complex (TSC) is caused by a mutation in the TSC1 or TSC2 genes. However, 15% of patients have no mutation identified. Tubers and subependymal nodules (SENs) are the typical brain lesions in TSC and are present in 90-95% of patients. The objective of this study is to characterize the specific genotype-phenotype of patients without these lesions. We analyzed the features of 11 patients without typical TSC neuroanatomic features. Ten had TSC1/TSC2 mutational analysis, which was negative. Clinically they had lesions thought to be of neural crest (NC) origin, such as hypomelanotic macules, facial angiofibromas, cardiac rhabdomyomas, angiomyolipomas, and lymphangioleiomyomatosis. We hypothesize that patients without tubers and SENs reflect mosaicism caused by a mutation in TSC1 or TSC2 in a NC cell during embryonic development. This may explain the negative results in TSC1 and TSC2 testing in DNA from peripheral leukocytes.

Increased endothelial activation in recently symptomatic versus asymptomatic carotid artery stenosis and in cerebral microembolic-signal-negative patient subgroups.

BACKGROUND AND PURPOSE: von Willebrand factor propeptide (VWF:Ag II) is potentially a more sensitive marker of acute endothelial activation than von Willebrand factor antigen (VWF:Ag). These biomarkers have not been simultaneously assessed in asymptomatic versus symptomatic carotid stenosis patients. The relationship between endothelial activation and cerebral microembolic signals (MESs) detected on transcranial Doppler ultrasound is unknown. METHODS: In this multicentre observational analytical study, plasma VWF:Ag and VWF:Ag II levels in patients with ≥50% asymptomatic carotid stenosis were compared with those from patients with ≥50% symptomatic carotid stenosis in the 'early' (≤4 weeks) and 'late' (≥3 months) phases after transient ischaemic attack or ischaemic stroke. Endothelial activation was also longitudinally assessed in symptomatic patients during follow-up. Transcranial Doppler ultrasound monitoring classified patients as MES-positive or MES-negative. RESULTS: Data from 31 asymptomatic patients were compared with those from 46 early symptomatic and 35 late phase symptomatic carotid stenosis patients, 23 of whom had undergone carotid intervention. VWF:Ag II levels were higher in early (12.8 µg/ml; P < 0.001), late (10.6 µg/ml; P = 0.01) and late post-intervention (10.6 µg/ml; P = 0.038) symptomatic patients than asymptomatic patients (8.9 µg/ml). VWF:Ag levels decreased in symptomatic patients followed up from the early to late phase after symptom onset (P = 0.048). Early symptomatic MES-negative patients had higher VWF: Ag II levels (13.3 vs. 9.0 µg/ml; P < 0.001) than asymptomatic MES-negative patients. CONCLUSIONS: Endothelial activation is enhanced in symptomatic versus asymptomatic carotid stenosis patients, in early symptomatic versus asymptomatic MES-negative patients, and decreases over time in symptomatic patients. VWF:Ag II levels are a more sensitive marker of endothelial activation than VWF:Ag levels in carotid stenosis. The potential value of endothelial biomarkers and concurrent cerebral MES detection at predicting stroke risk in carotid stenosis warrants further study.

The rheumatoid arthritis susceptibility polymorphism PTPN22 C1858T is not associated with leflunomide response or toxicity.

WHAT IS KNOWN AND OBJECTIVE: A common polymorphism (C1858T) in the gene that encodes the protein tyrosine phosphatase non-receptor type 22 (PTPN22) is associated with altered T-cell responses and increased susceptibility to rheumatoid arthritis (RA) and other autoimmune diseases. Teriflunomide, the active metabolite of leflunomide, reduces T-cell responses through inhibition of tyrosine kinase p56LCK. We examined a potential association between PTPN22 genotype and response or toxicity to leflunomide in Caucasian RA patients taking leflunomide in combination with other disease-modifying antirheumatic drugs (DMARDs). METHODS: Patients enrolled in the Royal Adelaide Hospital RA inception cohort and taking leflunomide were eligible for inclusion. Participants were followed for 12 months after leflunomide initiation or until either another DMARD was added or leflunomide was ceased. Clinical response according to change in 28-joint Disease Activity Score (DAS28) and cessation due to toxicity were assessed. RESULTS AND DISCUSSION: A total of 94 participants were included in the study, 75 of whom carried the CC genotype, 18 the CT, whereas one individual carried the TT genotype. Over the first 12 months of leflunomide treatment, there was no statistically significant relationship between carrying the T allele and change in DAS28 (-0·84 vs. -1·15, P = 0·446) nor with cessation of leflunomide treatment due to side effects (P = 0·433). These results indicate that PTPN22 C1858T genotype has no effect on response or toxicity outcomes in leflunomide-treated RA patients. WHAT IS NEW AND CONCLUSION: This is the first study to evaluate the biologically plausible hypothesis that PTPN22 genotype might be a predictor of response/toxicity to leflunomide therapy. Despite this, PTPN22 genotype was not associated with leflunomide response or toxicity in patients with RA.

Feasibility of a virtual reality course on adult tracheostomy safety skills.

The National Tracheostomy Safety Project has run high-quality, face-to-face skills courses since 2009. The aim of this project was to produce a virtual reality version of the established course and evaluate its impact on participant learning, and participant and faculty satisfaction. Healthcare staff and students were recruited and randomised to attend one of (1) a face-to-face traditional course (control); (2) a virtual reality course at a conference centre with on-site technical support; (3) a fully remote virtual reality course; the virtual reality groups were combined for the analysis of learning outcomes and satisfaction. The primary outcome was the difference in pre/post-course knowledge scores on a 30-item questionnaire; secondary outcomes included knowledge retention, usability, comfort/side effects and participant performance in a simulated tracheostomy emergency. Thirty-seven participants and 15 faculty participated in this study. There was no significant difference between mean pre/post-course scores from the face-to-face (from 21.1 to 23.1; +2) and combined virtual reality (from 17.1 to 21.1; +4) groups, with both showing improvement (p = 0.21). The mean System Usability Scale score for virtual reality was 76.8 (SD 12.6), which is above average; the median Simulator Sickness Questionnaire score was 7.5 (IQR 3.7-22.4), indicating minimal symptoms. All participants resolved the primary clinical problem in the simulated emergency, but the virtual reality (VR) group was slower overall (mean difference 61.8 s, p = 0.003). This technical feasibility study demonstrated that there was no difference in participant knowledge immediately after and 4 weeks following face-to-face and virtual reality courses. Virtual reality offers an immersive experience that can be delivered remotely and offers potential benefits of reducing travel and venue costs for attendees, therefore increasing the flexibility of training opportunities.

Widespread service fragmentation for patients and families with tuberous sclerosis complex (TSC) in the Republic of Ireland.

Background: Tuberous sclerosis complex (TSC) is a rare approximate 1:6000 birth incidence, a genetic disease with a wide variability of physical and neuropsychiatric symptoms. Patients require lifelong care from multiple healthcare specialities, for which International and United Kingdom (UK) TSC consensus recommendations exist. Personalised care delivered by a centralised coordinated team of TSC experts is recommended. There is no such service for the estimated 600 TSC patients in the Republic of Ireland (ROI) and there is a paucity of information regarding the healthcare of this group. Purpose: Evaluate the baseline care of patients with TSC attending epilepsy services in the Republic of Ireland (ROI) against UK TSC consensus recommendations. Methods: Patients with a diagnosis of TSC attending 12 adult and paediatric epilepsy centres in the ROI were identified. Clinical audits measured the baseline care of a subset of these patients against UK, TSC clinical recommendations. Data was anonymised and analysed at Trinity College Dublin. Results: One hundred thirty-five TSC patients attending twelve epilepsy centres were identified. Adults (n = 67) paediatric (n = 68). The care of 83 patients was audited (n = 63 ≥ 18 years) and (n = 20 < 18 years). Many baseline tests were completed, however, they required intra or interhospital referral. Care appears fragmented and there was no evidence of formal disease surveillance plans. Conclusions: The number of TSC patients attending epilepsy services is lower than expected (n = 135). Specialist services and treatments for TSC are available through informal referral pathways. Although UK, TSC consensus baseline recommendations are roughly adhered to, care is fragmented. Increased coordination of care could benefit disease management. Supplementary Information: The online version contains supplementary material available at 10.1007/s44162-024-00049-8.

Rapid in situ chondrocyte death induced by Staphylococcus aureus toxins in a bovine cartilage explant model of septic arthritis.

OBJECTIVE: To assess in situ chondrocyte viability following exposure to a laboratory strain and clinical isolates of Staphylococcus aureus. METHODS: Bovine cartilage explants were cultured in the presence of S. aureus 8325-4 (laboratory strain), clinical S. aureus isolates or non-infected culture medium of pH values 7.4, 6.4 and 5.4. All clinical isolates were isolated from the joint aspirates of patients presenting with S. aureus-induced septic arthritis (SA). At designated time points, in situ chondrocyte viability was assessed within defined regions-of-interest in the axial and coronal plane following live- and dead-cell image acquisition using the fluorescent probes 5-chloromethylfluorescein diacetate (CMFDA) and propidium iodide (PI), respectively, and confocal laser-scanning microscopy (CLSM). Cartilage water content, following S. aureus 8325-4 exposure, was obtained by measuring cartilage wet and dry weights. RESULTS: S. aureus 8325-4 and clinical S. aureus isolates rapidly reduced in situ chondrocyte viability (>45% chondrocyte death at 40 h). The increased acidity, observed during bacterial culture, had a minimal effect on chondrocyte viability. Chondrocyte death commenced within the superficial zone (SZ) and rapidly progressed to the deep zone (DZ). Simultaneous exposure of SZ and DZ chondrocytes to S. aureus 8325-4 toxins found SZ chondrocytes to be more susceptible to the toxins than DZ chondrocytes. Cartilage water content was not significantly altered compared to non-infected controls. CONCLUSIONS: Toxins released by S. aureus have a rapid and fatal action on in situ chondrocytes in this experimental model of SA. These data advocate the prompt and thorough removal of bacteria and their toxins during the treatment of SA.

Guided wave mode selection for health monitoring of sub-surface hidden defects on fuel weep holes.

The in situ health monitoring of defects on the blind side of open holes using ultrasonic plate waves is a challenging problem. Scattering phenomena in this hard-to-inspect region can be used indicate the presence of the defect. This is especially advantageous if these phenomena give rise to the scattering of a wave mode that is unique to the interaction between the incident wave mode and defect. When the defect in question is located within an inaccessible structure, an understanding of how the incident ultrasonic elastic wave field can be scattered from this hidden defect propagates to the accessible surface is important. This paper presents a series of computational investigations to highlight the essential physics that explains the scattering phenomena by a defect located on the blind side of an open hole. The work presented is relevant to the monitoring of defects located in hard-to-inspect regions of future unitized metallic and composite structures. The outcomes advance the knowledge base of inspection of hard-to-access regions with actuators and sensors placed in easily accessible locations.

Lung disease in the cystic fibrosis mouse exposed to bacterial pathogens.

Lung disease is the major cause of death in cystic fibrosis (CF), but there is no evidence for overt lung involvement at birth. We show here that the same is true for the gene targeted cftrm1HGU mutant mouse. Furthermore, this CF mouse model demonstrates an impaired capacity to clear Staphylococcus aureus and Burkholderia (Pseudomonas) cepacia, two opportunistic lung pathogens closely associated with lung disease in CF subjects. The cftrm1HGU homozygotes display mucus retention and frank lung disease in response to repeated microbial exposure. Thus, lung disease in the cftrm1HGU mouse develops in response to bacterial infection, establishing a model to dissect the pathogenesis of CF pulmonary disease and providing a clinically relevant end point to assess the efficacy of pharmacologic or genetic interventions.