Syndactyly in a novel Fras1(rdf) mutant results from interruption of signals for interdigital apoptosis.

BACKGROUND: Fras1 encodes an extracellular matrix protein that is critical for the establishment of the epidermal basement membrane during gestation. In humans, mutations in FRAS1 cause Fraser Syndrome (FS), a pleiotropic condition with many clinical presentations such as limb, eye, kidney, and craniofacial deformations. Many of these defects are mimicked by loss of Fras1 in mice, and are preceded by the formation of epidermal blisters in utero. RESULTS: In this study, we identified a novel ENU-derived rounded foot (rdf) mouse mutant with highly penetrant hindlimb soft-tissue syndactyly, among other structural defects. Mapping and sequencing revealed that rdf is a novel loss-of-function nonsense allele of Fras1 (Fras1(rdf)). Focusing on the limb, we found that the Fras1(rdf) syndactyly phenotype originates from loss of interdigital cell death (ICD). Despite normal expression of bone morphogenetic protein (BMP) ligands and their receptors, the BMP downstream target gene Msx2, which is also necessary and sufficient to promote ICD, was down-regulated in the interdigital regions of Fras1(rdf) hindlimb buds. CONCLUSIONS: The close correlation between limb bud epidermal blistering, decreased Msx2 expression, and reduced ICD in the Fras1(rdf) hindlimb buds suggests that epithelium detachment from the mesenchyme may create a physical gap that interrupts the transmission of BMP, among other signals, resulting in soft tissue syndactyly.

Establishment of smooth muscle and cartilage juxtaposition in the developing mouse upper airways.

In the trachea and bronchi of the mouse, airway smooth muscle (SM) and cartilage are localized to complementary domains surrounding the airway epithelium. Proper juxtaposition of these tissues ensures a balance of elasticity and rigidity that is critical for effective air passage. It is unknown how this tissue complementation is established during development. Here we dissect the developmental relationship between these tissues by genetically disrupting SM formation (through Srf inactivation) or cartilage formation (through Sox9 inactivation) and assessing the impact on the remaining lineage. We found that, in the trachea and main bronchi, loss of SM or cartilage resulted in an increase in cell number of the remaining lineage, namely the cartilage or SM, respectively. However, only in the main bronchi, but not in the trachea, did the loss of SM or cartilage lead to a circumferential expansion of the remaining cartilage or SM domain, respectively. In addition to SM defects, cartilage-deficient tracheas displayed epithelial phenotypes, including decreased basal cell number, precocious club cell differentiation, and increased secretoglobin expression. These findings together delineate the mechanisms through which a cell-autonomous disruption of one structural tissue can have widespread consequences on upper airway function.

Genome-scale study of transcription factor expression in the branching mouse lung.

BACKGROUND: Mammalian lung development consists of a series of precisely choreographed events that drive the progression from simple lung buds to the elaborately branched organ that fulfills the vital function of gas exchange. Strict transcriptional control is essential for lung development. Among the large number of transcription factors encoded in the mouse genome, only a small portion of them are known to be expressed and function in the developing lung. Thus a systematic investigation of transcription factors expressed in the lung is warranted. RESULTS: To enrich for genes that may be responsible for regional growth and patterning, we performed a screen using RNA in situ hybridization to identify genes that show restricted expression patterns in the embryonic lung. We focused on the pseudoglandular stage during which the lung undergoes branching morphogenesis, a cardinal event of lung development. Using a genome-scale probe set that represents over 90% of the transcription factors encoded in the mouse genome, we identified 62 transcription factor genes with localized expression in the epithelium, mesenchyme, or both. Many of these genes have not been previously implicated in lung development. CONCLUSIONS: Our findings provide new starting points for the elucidation of the transcriptional circuitry that controls lung development.

The PRONTO study: Clinical performance of ID NOW in individuals with compatible SARS-CoV-2 symptoms in walk-in centres-accelerated turnaround time for contact tracing.

Background: This PRONTO study investigated the clinical performance of the Abbott ID NOWTM (IDN) COVID-19 diagnostic assay used at point of care and its impact on turnaround time for divulgation of test results. Methods: Prospective study conducted from December 2020 to February 2021 in acute symptomatic participants presenting in three walk-in centres in the province of Québec. Results: Valid paired samples were obtained from 2,372 participants. A positive result on either the IDN or the standard-of-care nucleic acid amplification test (SOC-NAAT) was obtained in 423 participants (prevalence of 17.8%). Overall sensitivity of IDN and SOC-NAAT were 96.4% (95% CI: 94.2-98.0%) and 99.1% (95% CI: 97.6-99.8), respectively; negative predictive values were 99.2% (95% CI: 98.7-99.6%) and 99.8% (95% CI: 99.5-100%), respectively. Turnaround time for positive results was significantly faster on IDN. Conclusion: In our experience, IDN use in symptomatic individuals in walk-in centres is a reliable sensitive alternative to SOC-NAAT without the need for subsequent confirmation of negative results. Such deployment can accelerate contact tracing, reduce the burden on laboratories and increase access to testing.

Psychological therapy for mood instability within bipolar spectrum disorder: a randomised, controlled feasibility trial of a dialectical behaviour therapy-informed approach (the ThrIVe-B programme).

BACKGROUND: A subgroup of those with bipolar spectrum disorders experience ongoing mood fluctuations outside of full episodes. We conducted a randomised, controlled feasibility study of a Dialectical Behavioural Therapy-informed approach for bipolar mood fluctuations (Therapy for Inter-episode mood Variability in Bipolar [ThrIVe-B]). Our study aimed to examine the feasibility and acceptability of a future definitive trial evaluating the clinical and cost effectiveness of the ThrIVe-B programme. Participants were required to meet diagnostic criteria for a bipolar spectrum disorder and report frequent mood swings outside of acute episodes. They were randomised to treatment as usual (control arm) or the ThrIVe-B intervention plus treatment as usual (intervention arm). Follow-up points were at 3, 6, 9 and 15 months after baseline, with 9 months as the primary end point. To evaluate feasibility and acceptability we examined recruitment and retention rates, completion rates for study measures, adverse events and feedback from participants on their experience of study participation and therapy. RESULTS: Of the target 48 participants, 43 were recruited (22 in the intervention arm; 21 in the control arm), with a recruitment rate of 3.9 participants per month. At 9 months 74% of participants engaged in research follow-up assessment, exceeding the pre-specified criterion of 60%. There were no serious concerns about the safety of the research procedures or the intervention. On one of the four candidate primary outcome measures, the 95% CI for the between-group mean difference score excluded the null effect and included the minimal clinically important difference, favouring the intervention arm, whilst on no measure was there evidence of deterioration in the intervention arm relative to the control arm. Attendance of the intervention (50% attending at least half of the mandatory sessions) was below the pre-specified continuation criterion of 60%, and qualitative feedback from participants indicated areas that may have hampered or facilitated engagement. CONCLUSIONS: It is broadly feasible to conduct a trial of this design within the population of people with frequent bipolar mood swings. Changes should be made to the therapy to increase uptake, such as simplifying content and considering individual rather than group delivery. Trial registration ISRCTN: ISRCTN54234300. Registered 14th July 2017, http://www.isrctn.com/ISRCTN54234300.

The endovascular coronary sinus catheter in minimally invasive mitral and tricuspid valve surgery: a case series.

OBJECTIVES: To determine the safety and efficacy of a standardized approach to the use of an endovascular coronary sinus (CS) catheter during minimally invasive cardiac surgery. DESIGN: Case series. SETTING: University hospital. PARTICIPANTS: Patients undergoing mitral and/or tricuspid valve surgery using a minimally invasive cardiac surgery approach. INTERVENTIONS: An endovascular CS catheter was placed to enable the administration of retrograde cardioplegia using transesophageal echocardiography (TEE), fluoroscopy, and CS pressure measurements. MEASUREMENTS AND MAIN RESULTS: Data were collected from 96 patient records. A total of 95 (99.0%) endovascular coronary sinus catheters were positioned. The mean time to insert the catheter into the sinus ostium under TEE guidance was 6.3 ± 8.4 minutes. Confirmation of adequate positioning with fluoroscopy took an average of 9.1 ± 10.6 minutes for a mean total procedure time of 16.1 ± 14.1 minutes. Successful positioning, as defined by the ability to generate a perfusion pressure in the CS greater than 30 mmHg during surgery, was achieved in 87.5% of cases. During positioning, ventricularization of the CS pressure curve was observed in 86.0% of cases. The presence of ventricularization was associated with an increase in positioning success (odds ratio = 15.8; 95% confidence interval, 3.713-67.239). One patient developed extravasation of contrast agent after CS catheter placement, without evidence of CS rupture. CONCLUSIONS: Endovascular CS catheter insertion can be performed with a high rate of success for positioning and a low complication rate. During positioning, obtaining ventricularization is associated with an increased success rate.

Crouzon syndrome mouse model exhibits cartilage hyperproliferation and defective segmentation in the developing trachea.

Crouzon syndrome is the result of a gain-of-function point mutation in FGFR2. Mimicking the human mutation, a mouse model of Crouzon syndrome (Fgfr2342Y) recapitulates patient deformities, including failed tracheal cartilage segmentation, resulting in a cartilaginous sleeve in the homozygous mutants. We found that the Fgfr2C342Y/C342Y mutants exhibited an increase in chondrocytes prior to segmentation. This increase is due at least in part to over proliferation. Genetic ablation of chondrocytes in the mutant led to restoration of segmentation in the lateral but not central portion of the trachea. These results suggest that in the Fgfr2C342Y/C342Y mutants, increased cartilage cell proliferation precedes and contributes to the disruption of cartilage segmentation in the developing trachea.

The clinical and cost effectiveness of adapted dialectical behaviour therapy (DBT) for bipolar mood instability in primary care (ThrIVe-B programme): a feasibility study.

BACKGROUND: In bipolar spectrum disorder, some individuals experience ongoing, frequent fluctuations in mood outside of affective episodes. There are currently no evidence-based psychological interventions designed to address this. This feasibility study is a phase II evaluation of a dialectical behavioural therapy-informed approach (Therapy for Inter-episode mood Variability in Bipolar [ThrIVe-B]). It seeks to examine the feasibility and acceptability of a future definitive trial evaluating the clinical and cost effectiveness of the ThrIVe-B programme. METHODS/DESIGN: Patients will be randomised 1:1 to either treatment as usual only (control arm) or the ThrIVe-B intervention plus treatment as usual (intervention arm). Follow-up points will be at 3, 6, 9 and 15 months after baseline, with 9 months as the primary end point for the candidate primary outcome measures. We aim to recruit 48 individuals meeting diagnostic criteria for a bipolar spectrum disorder and reporting frequent mood swings outside of acute episodes, through primary and secondary care services and self-referral. To evaluate feasibility and acceptability, we will examine recruitment and retention rates, completion rates for study measures and feedback from participants on their experience of study participation and therapy. DISCUSSION: Proceeding to a definitive trial will be indicated if the following criteria are met: (1) trial participation does not lead to serious negative consequences for our participants; (2) any serious concerns about the acceptability and feasibility of the trial procedures can be rectified prior to a definitive trial; (3) follow-up data at 9 months are available for at least 60% of participants; (4) at least 60% of patients in the ThrIVe-B arm complete treatment. TRIAL REGISTRATION: ISRCTN, ISRCTN54234300 . Registered on 20 July 2017.