Perception and Representation of LGBTQ+ Individuals in U.S. Neurosurgical Training

OBJECTIVE

The aim of this study is to gauge the current social climate in neurosurgical residency training and attitudes regarding sexual orientation and gender identity.

METHODS

We conducted a cross-sectional study through a 35-question questionnaire distributed to roughly 1700 residents at all U.S. neurosurgical residency programs.

RESULTS

A total of 107 responses were obtained. Seventeen residents (16%) identified as being an LGBTQ+ individual. The majority (76%) of LGBTQ+ residents were concerned about how their sexual orientation would be perceived while applying to programs, and 47% endorsed purposefully concealing sexual orientation at work for fear of rejection or reprisal. More than half (56%) of those surveyed have witnessed homophobic/transphobic remarks by patients. While at work, 29% of LGBTQ+ individuals stated they are uncomfortable being open with their sexual orientation, and 3 LGBTQ+ individuals admitted being the target of direct homophobic/transphobic comments.

CONCLUSIONS

This is the first study to our knowledge that has been conducted assessing the presence, perception, and treatment of LGBTQ+ trainees in neurosurgical residency. Our study outlines the challenges LGBTQ+ individuals face when applying to neurosurgical programs, which involves the perception of their sexual orientation, their witnessed instances of homophobic and transphobic comments by coworkers and patients, and their hesitation with discussing their social lives compared with their non-LGBTQ+ peers at work for fear of judgment or reprisal. Ongoing research is needed to address these issues to obtain workplace respect and fairness in this population and thus create an accepting atmosphere and achieve social justice in neurosurgery training.

Micelle-Promoted Reductive Amination of DNA-Conjugated Amines for DNA-Encoded Library Synthesis

DNA-encoded libraries (DELs) have become a leading technology for hit identification in drug discovery projects as large, diverse libraries can be generated. DELs are commonly synthesised via split-and-pool methodology; thus, chemical transformations utilised must be highly efficient, proceeding with high conversions. Reactions performed in DEL synthesis also require a broad substrate scope to produce diverse, drug-like libraries. Many pharmaceutical compounds incorporate multiple C-N bonds, over a quarter of which are synthesised via reductive aminations. However, few on-DNA reductive amination procedures have been developed. Herein is reported the application of the micelle-forming surfactant, TPGS-750-M, to the on-DNA reductive amination of DNA-conjugated amines, yielding highly efficient conversions with a broad range of aldehydes, including medicinally relevant heterocyclic and aliphatic substrates. The procedure is compatible with DNA amplification and sequencing, demonstrating its applicability to DEL synthesis.

Age-associated changes in lineage composition of the enteric nervous system regulate gut health and disease

The enteric nervous system (ENS), a collection of neural cells contained in the wall of the gut, is of fundamental importance to gastrointestinal and systemic health. According to the prevailing paradigm, the ENS arises from progenitor cells migrating from the neural crest and remains largely unchanged thereafter. Here, we show that the lineage composition of maturing ENS changes with time, with a decline in the canonical lineage of neural-crest derived neurons and their replacement by a newly identified lineage of mesoderm-derived neurons. Single cell transcriptomics and immunochemical approaches establish a distinct expression profile of mesoderm-derived neurons. The dynamic balance between the proportions of neurons from these two different lineages in the post-natal gut is dependent on the availability of their respective trophic signals, GDNF-RET and HGF-MET. With increasing age, the mesoderm-derived neurons become the dominant form of neurons in the ENS, a change associated with significant functional effects on intestinal motility which can be reversed by GDNF supplementation. Transcriptomic analyses of human gut tissues show reduced GDNF-RET signaling in patients with intestinal dysmotility which is associated with reduction in neural crest-derived neuronal markers and concomitant increase in transcriptional patterns specific to mesoderm-derived neurons. Normal intestinal function in the adult gastrointestinal tract therefore appears to require an optimal balance between these two distinct lineages within the ENS.

Anatomic total shoulder arthroplasty with a nonspherical humeral head and inlay glenoid: 90-day complication profile in the inpatient versus outpatient setting

BACKGROUND

Total shoulder arthroplasty (TSA) with a nonspherical humeral head component and inlay glenoid is a successful bone-preserving treatment for glenohumeral arthritis. This study aimed to describe the 90-day complication profile of TSA with this prosthesis and compare major and minor complication and readmission rates between inpatient- and outpatient-procedure patients.

METHODS

A retrospective review was performed of a consecutive cohort of patients undergoing TSA with a nonspherical humeral head and inlay glenoid in the inpatient and outpatient settings by a single surgeon between 2017 and 2022. Age, sex, body mass index, American Society of Anesthesiologists (ASA) score, Charlson Comorbidity Index (CCI), and 90-day complication and readmission rates were compared between inpatient and outpatient groups.

RESULTS

One hundred eighteen TSAs in 111 patients were identified. Mean age was 64.9 years (range, 39-90) and 65% of patients were male. Ninety-four (80%) and 24 (20%) patients underwent outpatient and inpatient procedures, respectively. Four complications (3.4%) were recorded: axillary nerve stretch injury, isolated ipsilateral arm deep venous thrombosis (DVT), ipsilateral arm DVT with pulmonary embolism requiring readmission, and gastrointestinal bleed requiring readmission. There were no reoperations or other complications. Outpatients were younger with lower ASA and CCI scores than inpatients; however, there was no difference in complications (1/24 vs. 3/94, P=1.00) or readmissions (1/24 vs. 1/94, P=0.37) between these two groups.

CONCLUSIONS

TSA with a nonspherical humeral head and inlay glenoid can be performed safely in both inpatient and outpatient settings. Rates of early complications and readmissions were low with no difference according to surgical setting. Level of evidence: IV.

Preferences of Patients and Providers in High-Burden Malaria Settings for Long-Acting Malaria Chemoprevention

Antimalarial medications are recommended for chemoprevention as part of malaria control programs to decrease the morbidity and mortality related to more than 200 million infections each year. We sought to evaluate patient and provider acceptability of malaria chemoprevention in a long-acting formulation. We administered questionnaires to patients and providers in malaria endemic districts in Kenya and Zambia. Questions explored preferences and concerns around long-acting antimalarial formulations compared with oral formulations. We recruited 202 patient respondents (Kenya, n = 102; Zambia, n = 100) and 215 provider respondents (Kenya, n = 105; Zambia, n = 110). Long-acting injection was preferred to oral pills, whereas oral pills were preferred to implant or transdermal administration by patient respondents. Of 202 patient respondents, 80% indicated that they 'definitely would try' malaria chemoprevention offered by injection instead of oral pills. Of parents or guardians, 84% of 113 responded that they 'definitely would' have their child age < 12 years and 90% of 88 'definitely would' have their child ≥12 years receive an injection for malaria prevention. Provider respondents indicated that they would be more likely to prescribe a long-acting injectable product compared with an oral product for malaria chemoprevention in adults (70%), adolescents ages 12 years and older (67%), and children <12 years (81%). Potential for prolonged adverse effects with long-acting products was the highest concern for patient respondents, while higher medication-related cost was cited as the most concerning barrier to implementation by providers. Overall, these findings indicate enthusiasm for the development of long-acting injectable antimalarials to provide individual delivery method options across age groups.

Posteromedial Osteophyte Resection in Baseball Players Undergoing Ulnar Collateral Ligament Reconstruction Has no Effect on Return to Play but Decreases Patient-Reported Satisfaction and Throwing Control

Purpose

The purpose of this study was to compare patient-reported outcomes and return to play (RTP) rates following ulnar collateral ligament reconstruction (UCLR) in patients with and without posteromedial elbow impingement (PI) treated with concomitant arthroscopic posteromedial osteophyte resection.

Methods

Baseball players who underwent UCLR performed by the senior surgeon with minimum follow-up of 2 years were surveyed in this retrospective cohort study. Primary outcomes included Kerlan-Jobe Orthopaedic Clinic Shoulder and Elbow (KJOC) score, Andrews-Timmerman score, and RTP rate. Secondary outcomes included patient satisfaction scores.

Results

35 baseball players were included. Eighteen had no preoperative impingement (mean age: 19.06 ± 3.28 years), while 17 had PI treated with concomitant arthroscopic osteophyte resection (mean age: 20.06 ± 2.68 years). Following surgery, there was no difference in mean Andrews-Timmerman score (no impingement = 91.67 ± 8.04 vs PI = 92.06 ± 7.92, P = .89) nor KJOC score (no impingement = 83.36 ± 11.72 vs PI = 79.88 ± 12.35, P = .40), but there was a decreased mean KJOC throwing control sub-score in the PI group (7.65 ± 2.40 vs 9.11 ± 1.32, P = .04). There was no difference in RTP rate between the groups (no impingement = 72.22%, PI = 94.12%, χ² = 1.28; P = .26). There was significantly higher mean satisfaction score in the no impingement group (96.67 ± 4.58 vs 90.12 ± 11.91; P = .04), and those patients were also more likely to pursue surgical treatment again (94.44% vs 52.94%, χ² = 7.88; P = .005).

Conclusions

There was no difference in RTP rate following ulnar collateral ligament reconstruction in baseball players with and without posteromedial impingement treated with arthroscopic resection. Outcomes on the KJOC and Andrews-Timmerman scores were good to excellent in both groups. Players in the posteromedial impingement group were less satisfied with their outcome, however, and less likely to elect for surgery if they were to sustain the injury again. Additionally, players in the posteromedial impingement group were found to have decreased throwing control on the KJOC questionnaire, which may suggest that the presence of posteromedial osteophytes represent adaptive changes to stabilize the elbow while throwing.

Level of Evidence

Level III, retrospective cohort study.

Impact of oral Phytozen® EQ supplementation on plasma cortisol and behavior responses of young horses exposed to stressful stimuli

Calming supplements are common in the equine industry. This study tested the hypothesis that Phytozen® EQ, a blend of citrus botanical oils, magnesium, and yeast would reduce startle response as well as reduce behavioral and physiological signs of stress in young (1.5-6 years of age) horses (n = 14) when tied in isolation and when trailered in isolation. During the 59-day (d) trial, horses were assigned to either the control (CON; n=7) or treatment (PZEN; n=7) group that received 56 g of Phytozen® EQ daily. Horses underwent a 10 min isolation test on d 30 and a 15 min individual trailering test on day 52 or 55. For both tests, blood samples were obtained pre, immediately after, and 1-hour (h) post for analysis of plasma cortisol concentrations, which were analyzed by repeated measures ANOVA. On d 59, horses underwent a startle test, for which time to travel 3 m and total distance traveled were recorded. These data were analyzed using a T-test. During trailering, PZEN horses tended to have lower overall geometric mean (lower, upper 95% confidence interval) cortisol concentrations than CON (81 [67, 98] vs. 61 [48, 78] ng/mL; P = 0.071). For the startle test, PZEN horses tended to have longer geometric mean times to travel 3 m than CON horses (1.35 [0.39, 4.70] vs. 0.26 [0.07, 0.91 seconds [s], P = 0.064). Other data points were not different between treatments (P > 0.1). It is possible that this dietary supplement could have beneficial calming effects on horses undergoing trailering or in novel situations.

Systematic Assessment of the Quality and Comprehensibility of YouTube Content on Ulnar Collateral Ligament Injury and Management

Background

Ulnar collateral ligament (UCL) reconstruction has received a unique level of attention in the press and social media. There has also been an increasing use of the internet by patients to seek medical information. Concern exists regarding the quality and comprehensibility of online information when used for patient education.

Purpose

To evaluate the quality and comprehensibility of the most-viewed YouTube videos related to the diagnosis and management of UCL injuries. Based on our new evidence-based scoring rubrics, we hypothesized that the quality and comprehensibility of these videos would be poor.

Study Design

Cross-sectional study.

Methods

The YouTube platform was searched on September 7, 2021, with the terms "UCL injury," "ulnar collateral ligament injury," "UCL surgery," "ulnar collateral ligament surgery," and "Tommy John surgery," and the 50 most-viewed videos from each search were compiled, yielding 250 videos. After removal of duplicates and application of exclusion criteria, the 100 most-viewed videos remained. Basic attributes, including duration of video and number of views, were recorded. Each video was then analyzed by 2 independent reviewers and evaluated for 4 key parameters (quality of diagnostic content [QAR-D], quality of treatment content [QAR-T], presence of inaccurate information, and comprehensibility) and graded on a novel scale from 1 to 4 (4 being the most appropriate for patient education).

Results

The mean QAR-D was 4.83 ± 3.41 (fair quality), and the mean QAR-T was 2.76 ± 3.26 (poor quality). Physician-led educational videos had both the highest mean QAR-D (6.37) and the highest mean QAR-T (4.34). No correlation was observed between video quality and views/likes. A total of 12 videos included ≥1 inaccuracy. The mean comprehensibility score was 2.66 ± 1.12, with 39 videos falling below the acceptable comprehensibility threshold (score <3).

Conclusion

The overall quality of UCL injury-related YouTube content was low. In addition, the absence of correlation between video quality and views/likes suggests that patients are not preferentially utilizing the limited high-quality content that does exist on the YouTube platform. In addition, inaccurate videos were prevalent (12%), and almost half of all videos were deemed inappropriate for patient education in terms of comprehensibility, as defined by our comprehensibility parameter.

Fgf8 promotes survival of nephron progenitors by regulating BAX/BAK-mediated apoptosis

Fibroblast growth factors (Fgfs) have long been implicated in processes critical to embryonic development, such as cell survival, migration, and differentiation. Several mouse models of organ development ascribe a prosurvival requirement specifically to FGF8. Here, we explore the potential role of prosurvival FGF8 signaling in kidney development. We have previously demonstrated that conditional deletion of Fgf8 in the mesodermal progenitors that give rise to the kidney leads to renal aplasia in the mutant neonate. Deleterious consequences caused by loss of FGF8 begin to manifest by E14.5 when massive aberrant cell death occurs in the cortical nephrogenic zone in the rudimentary kidney as well as in the renal vesicles that give rise to the nephrons. To rescue cell death in the Fgf8 mutant kidney, we inactivate the genes encoding the pro-apoptotic factors BAK and BAX. In a wild-type background, the loss of Bak and Bax abrogates normal cell death and has minimal effect on renal development. However, in Fgf8 mutants, the combined loss of Bak and Bax rescues aberrant cell death in the kidneys and restores some measure of kidney development: 1) the nephron progenitor population is greatly increased; 2) some glomeruli form, which are rarely observed in Fgf8 mutants; and 3) kidney size is rescued by about 50% at E18.5. The development of functional nephrons, however, is not rescued. Thus, FGF8 signaling is required for nephron progenitor survival by regulating BAK/BAX and for subsequent steps involving, as yet, undefined roles in kidney development.

Cardiac progenitors instruct second heart field fate through Wnts

The heart develops in a synchronized sequence of proliferation and differentiation of cardiac progenitor cells (CPCs) from two anatomically distinct pools of cells, the first heart field (FHF) and second heart field (SHF). Congenital heart defects arise upon dysregulation of these processes, many of which are restricted to derivatives of the FHF or SHF. Of the conserved set of signaling pathways that regulate development, the Wnt signaling pathway has long been known for its importance in SHF development. The source of such Wnts has remained elusive, though it has been postulated that these Wnts are secreted from ectodermal or endodermal sources. The central question remains unanswered: Where do these Wnts come from? Here, we show that CPCs autoregulate SHF development via Wnt through genetic manipulation of a key Wnt export protein (Wls), scRNA-seq analysis of CPCs, and use of our precardiac organoid system. Through this, we identify dysregulated developmental trajectories of anterior SHF cell fate, leading to a striking single ventricle phenotype in knockout embryos. We then applied our findings to our precardiac organoid model and found that Wnt2 is sufficient to restore SHF cell fate in our model of disrupted endogenous Wnt signaling. In this study, we provide a basis for SHF cell fate decision-proliferation vs. differentiation-autoregulated by CPCs through Wnt.

Hepatic leukemia factor-expressing paraxial mesoderm cells contribute to the developing brain vasculature

Recent genetic lineage tracing studies reveal heterogeneous origins of vascular endothelial cells and pericytes in the developing brain vasculature, despite classical experimental evidence for a mesodermal origin. Here we provide evidence through a genetic lineage tracing experiment that cephalic paraxial mesodermal cells give rise to endothelial cells and pericytes in the developing mouse brain. We show that Hepatic leukemia factor (Hlf) is transiently expressed by cephalic paraxial mesenchyme at embryonic day (E) 8.0-9.0 and the genetically-marked E8.0 Hlf-expressing cells mainly contribute to the developing brain vasculature. Interestingly, the genetically-marked E10.5 Hlf-expressing cells, which have been previously reported to contain embryonic hematopoietic stem cells, fail to contribute to the vascular cells. Combined, our genetic lineage tracing data demonstrate that a transient expression of Hlf marks a cephalic paraxial mesenchyme contributing to the developing brain vasculature.

Return to Play Criteria Following Surgical Management of Osteochondral Defects of the Knee: A Systematic Review

OBJECTIVE

The objective of this study was to identify and describe the existing literature on criteria used for return to play (RTP) following surgical management of osteochondral defects of the knee.

DESIGN

A systematic review was performed to evaluate the surgical management of osteochondral defects of the knee in skeletally mature patients with a minimum of 2-year follow-up using Level I to IV studies in PubMed EMBASE from January 1998 to January 2016.

RESULTS

Twelve studies with at least one explicitly stated criterion for RTP were identified from a review of 253 published articles. The majority of included studies were Levels II and IV (33%, respectively). Autologous chondrocyte implantation (ACI) was exclusively evaluated in 33.3% of papers and 16.7% evaluated osteochondral allograft transplantation (OCA). Eight different RTP criteria were used alone or in combination across the reviewed studies and time was the most often utilized criterion (83.3%). Minimum time to RTP ranged from 3 to 18 months.

CONCLUSIONS

This systematic review identifies current criteria used in the available literature to dictate RTP. Time from surgery was the most commonly employed criterion across the reviewed studies. Given the complex biological processes inherent to the healing of cartilaginous defects, further research is needed to design more comprehensive guidelines for RTP that are patient-centered and utilize multiple functional and psychological domains relevant to the process of returning to sport.

Inactivation of Fgf3 and Fgf4 within the Fgf3/Fgf4/Fgf15 gene cluster reveals their redundant requirement for mouse inner ear induction and embryonic survival

BACKGROUND

Fibroblast growth factors (Fgfs) are required for survival and organ formation during embryogenesis. Fgfs often execute their functions redundantly. Previous analysis of Fgf3 mutants revealed effects on inner ear formation and embryonic survival with incomplete penetrance.

RESULTS

Here, we show that presence of a neomycin resistance gene (neo) replacing the Fgf3 coding region leads to reduced survival during embryogenesis and an increased penetrance of inner ear defects. Fgf3neo/neo mutants showed reduced expression of Fgf4, which is positioned in close proximity to the Fgf3 locus in the mouse genome. Conditional inactivation of Fgf4 during inner ear development on a Fgf3 null background using Fgf3/4 cis mice revealed a redundant requirement between these Fgfs during otic placode induction. In contrast, inactivation of Fgf3 and Fgf4 in the pharyngeal region where both Fgfs are also co-expressed using a Foxg1-Cre driver did not affect development of the pharyngeal arches. However, these mutants showed reduced perinatal survival.

CONCLUSIONS

These results highlight the importance of Fgf signaling during development. In particular, different members of the Fgf family act redundantly to guarantee inner ear formation and embryonic survival.

Team Approach: Developmental Dysplasia of the Hip

Developmental dysplasia of the hip (DDH) encompasses a wide spectrum of hip disorders, including neonatal instability, acetabular dysplasia, hip subluxation, and frank dislocation of the hip. It is a common disorder, with a reported incidence of between 0.1% and >10% of live births. Coordinated, interdisciplinary care is important to achieving successful outcomes. This starts with accurate assessment of risk factors in the prenatal period, thorough clinical examination by the primary care provider at all well-child visits, and early referral to a pediatric orthopaedic surgeon for prompt diagnosis and treatment. Early diagnosis and prompt treatment is critical for an excellent outcome. Ongoing, open communication between clinicians is essential for the effective coordination of care. Treatment options vary depending on the age of presentation. A Pavlik harness (dynamic hip abduction orthosis) is used for children up to 6 months of age. A more rigid abduction orthosis may be used if treatment with a Pavlik harness is unsuccessful, with a closed reduction and spica cast being the next step if needed for children up to 18 months of age. Finally, open reduction with possible concomitant femoral and/or pelvic osteotomies is the surgical option in an older child, when necessary. In general, the later the child is diagnosed with and treated for DDH, the greater the risk of a nonoptimal outcome. Depending on the severity of the condition, children with DDH may need to be followed closely until skeletal maturity so as not to miss the diagnosis of asymptomatic residual hip dysplasia, which can predispose patients to early hip arthritis.

Highly efficient on-DNA amide couplings promoted by micelle forming surfactants for the synthesis of DNA encoded libraries

DNA encoded libraries (DELs) represent powerful new technology for finding small molecule ligands for proteins and are increasingly being applied to hit finding in medicinal chemistry. Crucial to the synthesis of high quality DELs is the identification of chemical reactions for their assembly that proceed with very high conversion across a range of different substrates, under conditions compatible with DNA-tagged substrates. Many current chemistries used in DEL synthesis do not meet this requirement, resulting in libraries of low fidelity. Amide couplings are the most commonly used reaction in synthesis of screening libraries and also in DELs. The ability to carry out highly efficient, widely applicable amide couplings in DEL synthesis would therefore be highly desirable. We report a method for amide coupling using micelle forming surfactants, promoted by a modified linker, that is broadly applicable across a wide range of substrates. Most significantly, this works exceptionally well for coupling of DNA-conjugated carboxylic acids (N-to-C) with amines in solution, a procedure that is currently very inefficient. The optimisation of separate procedures for coupling of DNA-conjugated acids and amines by reagent screening and statistically driven optimisation is described. The generality of the method is illustrated by the application to a wide range of examples with unprecedented levels of conversion. The utility of the (N-to-C) coupling of DNA-conjugated acids in DEL synthesis is illustrated by the three cycle synthesis of a fully DNA-encoded compound by two cycles of coupling of an aminoester, with intermediate ester hydrolysis, followed by capping with an amine. This methodology will be of great utility in the synthesis of high fidelity DELs.

A Systematic Assessment of YouTube Content on Femoroacetabular Impingement: An Updated Review

Background:

Online video-sharing platforms such as YouTube have become popular sources of medical information for patients. However, concern exists regarding the quality of such non–peer reviewed content. In fact, a previous investigation found the majority of YouTube information related to femoroacetabular impingement (FAI) to be of poor quality.

Purpose:

To provide an updated assessment of the quality of FAI-related videos available on YouTube.

Study Design:

Cross-sectional study.

Methods:

The terms FAI, femoroacetabular impingement, and hip impingement were searched on YouTube, and exclusion criteria were applied to the first 100 results for each term. The diagnostic and treatment content of each video was graded and assigned a quality assessment rating based on a previously used rubric. Video characteristics (e.g. duration, views, “likes”) were compared using both quality assessment rating and video source.

Results:

A total of 142 videos were included in the final analysis. The most common video source was educational (48.6%), followed by physician-sponsored (30.3%). The majority of videos were graded as “somewhat useful” for both diagnostic and treatment content (59.4% and 61.6%, respectively); however, treatment content was rated “not useful” more often than diagnostic information (20.3% vs. 8.7%, respectively). Videos rated as “somewhat useful” received the most views per day on average, while educational videos were the most viewed by source (views and views per day). Educational videos had more views and likes on average than physician-sponsored videos (P < .05), but all other comparisons of video characteristics by source were not significant. Video duration was the only characteristic found to vary significantly by quality assessment rating (P < .001 for both diagnostic and treatment analyses), with higher-quality videos tending to be longer. Videos rated as “excellent” and “very useful” had mean durations >30 minutes but were viewed the least.

Conclusion:

The overall quality of FAI-related content on YouTube remains low. Clinicians should be familiar with medical information available to patients on the internet, as it can influence patients’ perspectives and shared decision-making processes. This review substantiates the need for more publicly available, high-quality video content regarding the diagnosis and treatment of FAI.

Fgf4 maintains Hes7 levels critical for normal somite segmentation clock function

During vertebrate development, the presomitic mesoderm (PSM) periodically segments into somites, which will form the segmented vertebral column and associated muscle, connective tissue, and dermis. The periodicity of somitogenesis is regulated by a segmentation clock of oscillating Notch activity. Here, we examined mouse mutants lacking only Fgf4 or Fgf8, which we previously demonstrated act redundantly to prevent PSM differentiation. Fgf8 is not required for somitogenesis, but Fgf4 mutants display a range of vertebral defects. We analyzed Fgf4 mutants by quantifying mRNAs fluorescently labeled by hybridization chain reaction within Imaris-based volumetric tissue subsets. These data indicate that FGF4 maintains Hes7 levels and normal oscillatory patterns. To support our hypothesis that FGF4 regulates somitogenesis through Hes7, we demonstrate genetic synergy between Hes7 and Fgf4, but not with Fgf8. Our data indicate that Fgf4 is potentially important in a spectrum of human Segmentation Defects of the Vertebrae caused by defective Notch oscillations.

Inter- and Intraobserver Reliability Between Orthopaedic Surgeons for Reparability of the Anterior Cruciate Ligament Using MRI

Background

Anterior cruciate ligament (ACL) reconstruction is the standard of care for patients after an ACL tear, as poor historical outcomes were observed after primary ACL repair. Certain subgroups of patients, however, have been shown to have outcomes equivalent to reconstruction after undergoing ACL repair and therefore may benefit from the potential advantages offered by avoiding reconstruction. It is important to accurately and consistently identify and indicate these candidates for ACL repair.

Purpose/Hypothesis

The purpose of this study was to determine the inter- and intraobserver reliability of magnetic resonance imaging (MRI) evaluation for the reparability of ACL tears and to identify imaging factors that may lead to surgeon uncertainty or disagreement in decision making. Our hypothesis was that the orthopaedic surgeons surveyed would not be able to reliably agree on the reparability of an ACL using MRI scans alone.

Study Design

Cohort study (diagnosis); Level of evidence, 3.

Methods

We administered 2 surveys to 6 fellowship-trained orthopaedic sports medicine surgeons. Each surgeon reviewed preoperative MRI scans for 20 patients and answered a series of questions, ultimately determining whether they would choose an ACL reconstruction or repair for the patient based on the imaging alone. The same survey was repeated 6 weeks later. Kappa values for inter- and intraobserver reliability of their decision making were then calculated.

Results

The average kappa for interobserver reliability in the 2 surveys was 0.22, and the average kappa for intraobserver reliability was 0.34. Interobserver reliability among the surgeons in this group was poor to moderate; intraobserver reliability was slightly better. The choice for ACL repair was significantly correlated with proximal tear locations (r = 0.854; P < .001), good-quality ACL tissue remnant (r = 0.929; P < .001), and how many surgeons believed that the tear only involved a single bundle (r = 0.590; P = .006).

Conclusion

The surgeons surveyed in this study did not consistently agree on candidates for ACL repair using MRI alone.

C-CBL is required for inhibition of angiogenesis through modulating JAK2/STAT3 activity in ROP development

Purpose:

The incidence of retinopathy of prematurity (ROP) has increased continuously in recent years. However, the therapeutic effects of current treatments still remain undesired. This study aims to investigate the role of C-CBL in retinal angiogenesis in ROP and its potential as a therapeutic target.

Methods:

Mouse retina microvascular endothelial cells (mRMECs) and induced experimental ROP/ oxygen-induced retinopathy (OIR) mice were employed to investigate the role of C-CBL in angiogenesis with combined molecular and cellular approaches, and histopathology methods. OIR mouse pups at postnatal day 12 (P12) were either injected intravitreally with adenovirus overexpressing c-Cbl or c-Cbl siRNA. Retinal neovascularization and avascular status were evaluated by retinal immunofluorescence (IF) staining, whole-mounts and hematoxylin and eosin (H&E) staining.

Results:

C-CBL inhibits neovascularization by negatively regulating JAK2/STAT3/VEGF signaling axis in a ubiquitination-dependent manner. Knockdown of c-Cbl by siRNA reduced ubiquitin-mediated JAK2 degradation and increased levels of p-JAK2, p-STAT3, VEGF, and neovascularization in mRMECs, which can be reversed by JAK2 inhibitor treatment. While knockdown of c-Cbl significantly increased neovascular (NV) zone in the retinas, c-Cbl overexpression inhibited neovascularization in the retinal tissues in OIR mice.

Conclusion:

We found that C-CBL is required for anti-neovascularization process in ROP development by inhibiting JAK2/STAT3-dependent angiogenesis. Thus, our finding strongly suggest that C-CBL may be a potential novel therapeutic target for treating ROP.

The Fgf8 subfamily (Fgf8, Fgf17 and Fgf18) is required for closure of the embryonic ventral body wall

The closure of the embryonic ventral body wall in amniotes is an important morphogenetic event and is essential for life. Defects in human ventral wall closure are a major class of birth defect and a significant health burden. Despite this, very little is understood about how the ventral body wall is formed. Here, we show that fibroblast growth factor (FGF) ligands FGF8, FGF17 and FGF18 are essential for this process. Conditional mouse mutants for these genes display subtle migratory defects in the abdominal muscles of the ventral body wall and an enlarged umbilical ring, through which the internal organs are extruded. By refining where and when these genes are required using different Cre lines, we show that Fgf8 and Fgf17 are required in the presomitic mesoderm, whereas Fgf18 is required in the somites. This study identifies complex and multifactorial origins of ventral wall defects and has important implications for understanding their origins during embryonic development.

Proximo-distal positional information encoded by an Fgf-regulated gradient of homeodomain transcription factors in the vertebrate limb

The positional information theory proposes that a coordinate system provides information to embryonic cells about their position and orientation along a patterning axis. Cells interpret this information to produce the appropriate pattern. During development, morphogens and interpreter transcription factors provide this information. We report a gradient of Meis homeodomain transcription factors along the mouse limb bud proximo-distal (PD) axis antiparallel to and shaped by the inhibitory action of distal fibroblast growth factor (FGF). Elimination of Meis results in premature limb distalization and HoxA expression, proximalization of PD segmental borders, and phocomelia. Our results show that Meis transcription factors interpret FGF signaling to convey positional information along the limb bud PD axis. These findings establish a new model for the generation of PD identities in the vertebrate limb and provide a molecular basis for the interpretation of FGF signal gradients during axial patterning.

Pan-cancer analysis of whole genomes

Cancer is driven by genetic change, and the advent of massively parallel sequencing has enabled systematic documentation of this variation at the whole-genome scale1-3. Here we report the integrative analysis of 2,658 whole-cancer genomes and their matching normal tissues across 38 tumour types from the Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium of the International Cancer Genome Consortium (ICGC) and The Cancer Genome Atlas (TCGA). We describe the generation of the PCAWG resource, facilitated by international data sharing using compute clouds. On average, cancer genomes contained 4-5 driver mutations when combining coding and non-coding genomic elements; however, in around 5% of cases no drivers were identified, suggesting that cancer driver discovery is not yet complete. Chromothripsis, in which many clustered structural variants arise in a single catastrophic event, is frequently an early event in tumour evolution; in acral melanoma, for example, these events precede most somatic point mutations and affect several cancer-associated genes simultaneously. Cancers with abnormal telomere maintenance often originate from tissues with low replicative activity and show several mechanisms of preventing telomere attrition to critical levels. Common and rare germline variants affect patterns of somatic mutation, including point mutations, structural variants and somatic retrotransposition. A collection of papers from the PCAWG Consortium describes non-coding mutations that drive cancer beyond those in the TERT promoter4; identifies new signatures of mutational processes that cause base substitutions, small insertions and deletions and structural variation5,6; analyses timings and patterns of tumour evolution7; describes the diverse transcriptional consequences of somatic mutation on splicing, expression levels, fusion genes and promoter activity8,9; and evaluates a range of more-specialized features of cancer genomes8,10-18.

A computational study on the three-dimensional printability of precipitate-strengthened nickel-based superalloys

This paper presents a computational framework to study the differences in process-induced microvoid and precipitate distributions during selective laser melting (SLM) of two nickel-based superalloys representative of low (IN718) and high (CM247LC) volume fraction precipitate-strengthened alloys. Simulations indicate that CM247LC has a higher propensity to form process-induced microvoids than IN718. Particle sintering is predicted to be strongly influenced by the powder size distribution. For deposition thickness of approximately 40 μm, thermal gradients during cooling are predicted to be larger for CM247LC than IN718 and consequently expect the development of larger residual stresses for a high volume fraction γ' alloy. A coupled mean field/finite-element approach has been used to predict the precipitate distributions across a simple rectangular build and during a subsequent hot isostatic pressing (HIP) cycle. Unimodal and multi-modal particle distributions are predicted for IN718 and CM247LC at the end of the SLM, respectively. A higher volume fraction of γ' is predicted for CM247LC at the end of the SLM process. During HIP, simulations indicate a dramatic increase in the γ' volume fraction in CM247LC, which can result in a reduction in stress relaxation and lead to a ductility drop.

Coordinated directional outgrowth and pattern formation by integration of Wnt5a and Fgf signaling in planar cell polarity

Embryonic morphogenesis of a complex organism requires proper regulation of patterning and directional growth. Planar cell polarity (PCP) signaling is emerging as a crucial evolutionarily conserved mechanism whereby directional information is conveyed. PCP is thought to be established by global cues, and recent studies have revealed an instructive role of a Wnt signaling gradient in epithelial tissues of both invertebrates and vertebrates. However, it remains unclear whether Wnt/PCP signaling is regulated in a coordinated manner with embryonic patterning during morphogenesis. Here, in mouse developing limbs, we find that apical ectoderm ridge-derived Fgfs required for limb patterning regulate PCP along the proximal-distal axis in a Wnt5a-dependent manner. We demonstrate with genetic evidence that the Wnt5a gradient acts as a global cue that is instructive in establishing PCP in the limb mesenchyme, and that Wnt5a also plays a permissive role to allow Fgf signaling to orient PCP. Our results indicate that limb morphogenesis is regulated by coordination of directional growth and patterning through integration of Wnt5a and Fgf signaling.

Corrigendum: Whole-genome landscape of pancreatic neuroendocrine tumours

This corrects the article DOI: 10.1038/nature21063.

Lateral asymmetry in the freely occurring behaviour of budgerigars (Melopsittacus undulatus) and its relation to cognitive performance

Hemispheric laterality and its provision of potential fitness advantages to aves is a widespread topic of research in budgerigars and other parrot species [e.g., Magat, M. & Brown, C. (2009). Laterality enhances cognition in Australian parrots. Proceedings of the Royal Society B: Biological Sciences, 276, 4155-4162]. In the current study, lateral preferences were tracked for 11 captive-reared budgerigars that subsequently underwent 2 cognitive problem-solving tests: a tool-use problem and a dig-discrimination task. Two significant individual-level lateral preferences (a leftward unipedal support preference and a rightward preening side preference) and 1 significant population-level preference (a right-side preening preference) were obtained. Lateral preening side preference indices for individual subjects correlated with various measures of performance on the dig task, such that right-side preening preferences and stronger lateral preferences irrespective of direction were associated with enhanced dig task performance. The data generally support the idea that laterality in aves serves as a good predictor of increased cognitive capability, while also offering new evidence for population-level lateral preferences in the species.

Do small changes in rotation affect measurements of lower extremity limb alignment?

BACKGROUND

The alignment of the lower extremity has important implications in the development of knee arthritis. The effect of incremental rotations of the limb on common parameters of alignment has not been studied. The purpose of the study was to (1) determine the standardized neutral position measurements of alignment and (2) determine the effect of rotation on commonly used measurements of alignment.

METHODS

Eighty-seven full length CT angiography studies (49 males and 38 females, average age 66 years old) were included. Three-dimensional models were created using a rendering software program and placed on a virtual plane. An image of the extremity was obtained. Thirty scans were randomly selected, and those models were rotated in 3° intervals around the longitudinal axis and additional images were obtained.

RESULTS

In the neutral position, the mechanical lateral distal femoral articular angle (mLDFA) was 85.6 ± 2.3°, medial proximal tibial angle (MPTA) was 86.1 ± 2.8°, and mechanical tibiofemoral angle (mTFA) was -0.7 ± 3.1°. Females had a more valgus alignment with a mTFA of 0.5 ± 2.9° while males had a more varus alignment with a mTFA of -1.7 ± 2.9°. The anatomic tibiofemoral angle (aTFA) was 4.8 ± 2.6°, the anatomic lateral distal femoral angle (aLDFA) measured 80.2 ± 2.2°, and the anatomical-mechanical angle (AMA) was 5.4 ± 0.7°. The prevalence of constitutional varus was 18%. The effect of rotation on the rotated scans led to statistically significant differences relative to the 0° measurement for all measurements. These effects may be small, and their clinical importance is unknown.

CONCLUSIONS

This study provides new information on standardized measures of lower extremity alignment and the relationship between discreet axial rotations of the entire lower extremity and these parameters.

Whole-genome landscape of pancreatic neuroendocrine tumours

The diagnosis of pancreatic neuroendocrine tumours (PanNETs) is increasing owing to more sensitive detection methods, and this increase is creating challenges for clinical management. We performed whole-genome sequencing of 102 primary PanNETs and defined the genomic events that characterize their pathogenesis. Here we describe the mutational signatures they harbour, including a deficiency in G:C > T:A base excision repair due to inactivation of MUTYH, which encodes a DNA glycosylase. Clinically sporadic PanNETs contain a larger-than-expected proportion of germline mutations, including previously unreported mutations in the DNA repair genes MUTYH, CHEK2 and BRCA2. Together with mutations in MEN1 and VHL, these mutations occur in 17% of patients. Somatic mutations, including point mutations and gene fusions, were commonly found in genes involved in four main pathways: chromatin remodelling, DNA damage repair, activation of mTOR signalling (including previously undescribed EWSR1 gene fusions), and telomere maintenance. In addition, our gene expression analyses identified a subgroup of tumours associated with hypoxia and HIF signalling.

Osteophyte formation after ACL rupture in mice is associated with joint restabilization and loss of range of motion

Osteophytes are a typical radiographic finding during osteoarthritis (OA). Osteophytes are thought to form in response to joint instability; however, the time course of osteophyte formation and joint stabilization following joint injury is not well understood. In this study, we investigated the time course of osteophyte formation and joint function following non-invasive knee injury in mice. We hypothesized that initial joint instability following knee injury would initiate osteophyte formation, which would in turn restabilize the joint and reduce range of motion (ROM). Mice were subjected to non-invasive anterior cruciate ligament (ACL) rupture. Anterior-posterior (AP) joint laxity, ROM, and chondro/osteophyte formation were measured immediately after injury, and 2, 4, 6, and 8 weeks post-injury. Chondrophyte areas at each time point were measured with histology, while mineralized osteophyte volume was determined using micro-computed tomography. Immediately after ACL rupture, AP joint laxity was increased twofold, while ROM was increased 11.7%. Chondrophytes appeared by 2 weeks post-injury, corresponding with a decrease in AP joint laxity and ROM. By 8 weeks post-injury, considerable osteophyte formation was observed around the joint, AP joint laxity returned to control levels, and joint ROM decreased to 61% of control values. These data support a role for chondro/osteophytes in joint restabilization after injury, and provide crucial insight into the time course and pathology of joint degeneration during OA development in the mouse. Statement of Clinical Significance: Results from this study increase understanding of conditions leading to osteophyte formation.© 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:466-473, 2017.

Personality types in Budgerigars, Melopsittacus undulatus

The current study further characterized personality types in Budgerigars, an avian model that only recently demonstrated individual consistencies in behavior (Callicrate et al., 2011). Several methodological techniques, commonly used in previous examinations of other animal models, were employed. Specifically, Phase I assessed the relationship between Budgerigar personality types and Hypothalamic-Pituitary-Adrenal (HPA) activity, while Phase II sought to examine the persistence of individual behavioral tendencies across varying testing contexts. In comparison to other species, our findings failed to illustrate a clear relationship between Budgerigar personality types and concentrations of corticosterone. However, results provided significant evidence for the consistency of personalities across multiple contexts. In sum, our investigation further defined the expression of personality in the Budgerigar and substantiated the claim for individual tendencies in this species.

Budgie in the mirror: An exploratory analysis of social behaviors and mirror use in the Budgerigar (Melopsittacus undulatus)

Despite their prevalent use amongst avian species, particularly in Budgerigars, the relationship between mirror use and social behaviors is in need of elucidation. After establishing social behavior measures (e.g., agonistic and pair-bond data) in a colony of Budgerigars, mirrors were introduced and subsequent use was documented. Results illustrated a significant relationship between mirror use and pair-bonds, such that mirror use increased with increasing pair-bond strength. The authors posit that individual differences in gregariousness may best account for the obtained results, with certain birds seeking more social stimulation than others, whether it be from a pair-bond or from its own reflected mirror image. Additionally, the trends observed within agonistic behaviors were consistent with previous avian literature such that those who initiated more encounters also won more encounters and that there was a preference to be closer to birds that win more encounters.

Contribution of mechanical unloading to trabecular bone loss following non-invasive knee injury in mice

Development of osteoarthritis commonly involves degeneration of epiphyseal trabecular bone. In previous studies, we observed 30-44% loss of epiphyseal trabecular bone (BV/TV) from the distal femur within 1 week following non-invasive knee injury in mice. Mechanical unloading (disuse) may contribute to this bone loss; however, it is unclear to what extent the injured limb is unloaded following injury, and whether disuse can fully account for the observed magnitude of bone loss. In this study, we investigated the contribution of mechanical unloading to trabecular bone changes observed following non-invasive knee injury in mice (female C57BL/6N). We investigated changes in gait during treadmill walking, and changes in voluntary activity level using Open Field analysis at 4, 14, 28, and 42 days post-injury. We also quantified epiphyseal trabecular bone using μCT and weighed lower-limb muscles to quantify atrophy following knee injury in both ground control and hindlimb unloaded (HLU) mice. Gait analysis revealed a slightly altered stride pattern in the injured limb, with a decreased stance phase and increased swing phase. However, Open Field analysis revealed no differences in voluntary movement between injured and sham mice at any time point. Both knee injury and HLU resulted in comparable magnitudes of trabecular bone loss; however, HLU resulted in considerably more muscle loss than knee injury, suggesting another mechanism contributing to bone loss following injury. Altogether, these data suggest that mechanical unloading likely contributes to trabecular bone loss following non-invasive knee injury, but the magnitude of this bone loss cannot be fully explained by disuse. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1680-1687, 2016.

Effects of Ontogeny on Performance of Rats in a Novel Object-Recognition Task

The current experiment investigated ontogenetic forgetting on a novel object-recognition task similar to that of Besheer and Bevins. 18-day-old pups ( n = 49) and adult ( n = 29) rats were tested at two retention intervals (1 min. or 120 min.). By employing exclusion criteria which demanded minimum amounts of object exploration at training and test, the performance of 18-day-old pups but not that of adults was significantly impaired at 120 min. relative to 1 min. Analysis indicated that the ontogeny of the learning and memory measured in novel object recognition follows a developmental trend similar to that of other forms of learning, with older animals remembering more and thus performing better than younger animals. Unfortunately, given the extreme variability inherent to the task and large N necessary to achieve significance, the use of this task in studies of learning, memory, and development is discouraged.

Effects of supplemental lysine and methionine with zilpaterol hydrochloride on feedlot performance, carcass merit, and skeletal muscle fiber characteristics in finishing feedlot cattle

Feeding zilpaterol hydrochloride (ZH) with ruminally protected AA was evaluated in a small-pen feeding trial. Crossbred steers ( = 180; initial BW = 366 kg) were blocked by weight and then randomly assigned to treatments (45 pens; 9 pens/treatment). Treatment groups consisted of no ZH and no AA (Cont-), ZH and no AA (Cont+), ZH and a ruminally protected lysine supplement (Lys), ZH and a ruminally protected methionine supplement (Met), and ZH and ruminally protected lysine and methionine (Lys+Met). Zilpaterol hydrochloride (8.3 mg/kg DM) was fed for the last 20 d of the finishing period with a 3-d withdrawal period. Lysine and Met were top dressed daily for the 134-d feeding trial to provide 12 or 4 g·hd·d, respectively, to the small intestine. Carcass characteristics, striploins, and prerigor muscle samples were collected following harvest at a commercial facility. Steaks from each steer were aged for 7, 14, 21, and 28 d, and Warner-Bratzler shear force (WBSF) was determined as an indicator of tenderness. Prerigor muscle samples were used for immunohistological analysis. Cattle treated with Met and Lys+Met had increased final BW ( < 0.3) and ADG ( < 0.05) compared to Cont- and Cont+. Supplementation of Lys, Met, and Lys+Met improved G:F ( < 0.05) compared to Cont- during the ZH feeding period (d 111 to 134) as well as the entire feeding period ( < 0.05). Zilpaterol hydrochloride increased carcass ADG ( < 0.05) when compared to non-ZH-fed steers. Methionine and Lys+Met treatments had heavier HCW ( < 0.02) than that of Cont-. Yield grade was decreased ( < 0.04) for Cont+ steers compared to steers treated with Lys, Lys+Met, and Cont-. Tenderness was reduced ( < 0.05) with ZH regardless of AA supplementation. Lysine, Met, Lys+Met, and Cont+ had less tender steaks ( < 0.05) throughout all aging groups compared to Cont-. Steaks from Lys-treated steers were less tender ( < 0.05) than those of Cont+ during the 7- and 14-d aging periods. Nuclei density was the greatest with Cont- cattle compared to all other treatments suggesting a dilution effect of the nuclei in the larger muscle fibers with ZH feeding. Supplementation of Met in conjunction with ZH feeding increased ADG and HCW although this may lead to decreased tenderness even after aging for 28 d. These findings indicated that steers fed ZH may require additional AA absorbed from the small intestine to maximize performance.

An FGF3-BMP Signaling Axis Regulates Caudal Neural Tube Closure, Neural Crest Specification and Anterior-Posterior Axis Extension

During vertebrate axis extension, adjacent tissue layers undergo profound morphological changes: within the neuroepithelium, neural tube closure and neural crest formation are occurring, while within the paraxial mesoderm somites are segmenting from the presomitic mesoderm (PSM). Little is known about the signals between these tissues that regulate their coordinated morphogenesis. Here, we analyze the posterior axis truncation of mouse Fgf3 null homozygotes and demonstrate that the earliest role of PSM-derived FGF3 is to regulate BMP signals in the adjacent neuroepithelium. FGF3 loss causes elevated BMP signals leading to increased neuroepithelium proliferation, delay in neural tube closure and premature neural crest specification. We demonstrate that elevated BMP4 depletes PSM progenitors in vitro, phenocopying the Fgf3 mutant, suggesting that excessive BMP signals cause the Fgf3 axis defect. To test this in vivo we increased BMP signaling in Fgf3 mutants by removing one copy of Noggin, which encodes a BMP antagonist. In such mutants, all parameters of the Fgf3 phenotype were exacerbated: neural tube closure delay, premature neural crest specification, and premature axis termination. Conversely, genetically decreasing BMP signaling in Fgf3 mutants, via loss of BMP receptor activity, alleviates morphological defects. Aberrant apoptosis is observed in the Fgf3 mutant tailbud. However, we demonstrate that cell death does not cause the Fgf3 phenotype: blocking apoptosis via deletion of pro-apoptotic genes surprisingly increases all Fgf3 defects including causing spina bifida. We demonstrate that this counterintuitive consequence of blocking apoptosis is caused by the increased survival of BMP-producing cells in the neuroepithelium. Thus, we show that FGF3 in the caudal vertebrate embryo regulates BMP signaling in the neuroepithelium, which in turn regulates neural tube closure, neural crest specification and axis termination. Uncovering this FGF3-BMP signaling axis is a major advance toward understanding how these tissue layers interact during axis extension with important implications in human disease.

During embryological development, the vertebrate embryo undergoes profound growth in a head-to-tail direction. During this process, formation of different structures within adjacent tissue layers must occur in a coordinated fashion. Insights into how these adjacent tissues molecularly communicate with each other is essential to understanding both basic embryology and the underlying causes of human birth defects. Mice lacking Fgf3, which encodes a secreted signaling factor, have long been known to have premature axis termination, but the underlying mechanism has not been studied until now. Through a series of complex genetic experiments, we show that FGF3 is an essential factor for coordination of neural tube development and axis extension. FGF3 is secreted from the mesodermal layer, which is the major driver of extending the axis, and negatively regulates expression of another class of secreted signaling molecules in the neuroepithelium, BMPs. In the absence of FGF3, excessive BMP signals cause a delay in neural tube closure, premature specification of neural crest cells and negatively affect the mesoderm, causing a premature termination of the embryological axis. Our work suggests that FGF3 may be a player in the complex etiology of the human birth defect, spina bifida, the failure of posterior neural tube closure.

Genomic analyses identify molecular subtypes of pancreatic cancer

Integrated genomic analysis of 456 pancreatic ductal adenocarcinomas identified 32 recurrently mutated genes that aggregate into 10 pathways: KRAS, TGF-β, WNT, NOTCH, ROBO/SLIT signalling, G1/S transition, SWI-SNF, chromatin modification, DNA repair and RNA processing. Expression analysis defined 4 subtypes: (1) squamous; (2) pancreatic progenitor; (3) immunogenic; and (4) aberrantly differentiated endocrine exocrine (ADEX) that correlate with histopathological characteristics. Squamous tumours are enriched for TP53 and KDM6A mutations, upregulation of the TP63∆N transcriptional network, hypermethylation of pancreatic endodermal cell-fate determining genes and have a poor prognosis. Pancreatic progenitor tumours preferentially express genes involved in early pancreatic development (FOXA2/3, PDX1 and MNX1). ADEX tumours displayed upregulation of genes that regulate networks involved in KRAS activation, exocrine (NR5A2 and RBPJL), and endocrine differentiation (NEUROD1 and NKX2-2). Immunogenic tumours contained upregulated immune networks including pathways involved in acquired immune suppression. These data infer differences in the molecular evolution of pancreatic cancer subtypes and identify opportunities for therapeutic development.

FGF-Regulated ETV Transcription Factors Control FGF-SHH Feedback Loop in Lung Branching

The mammalian lung forms its elaborate tree-like structure following a largely stereotypical branching sequence. While a number of genes have been identified to play essential roles in lung branching, what coordinates the choice between branch growth and new branch formation has not been elucidated. Here we show that loss of FGF-activated transcription factor genes, Etv4 and Etv5 (collectively Etv), led to prolonged branch tip growth and delayed new branch formation. Unexpectedly, this phenotype is more similar to mutants with increased rather than decreased FGF activity. Indeed, an increased Fgf10 expression is observed, and reducing Fgf10 dosage can attenuate the Etv mutant phenotype. Further evidence indicates that ETV inhibits Fgf10 via directly promoting Shh expression. SHH in turn inhibits local Fgf10 expression and redirects growth, thereby initiating new branches. Together, our findings establish ETV as a key node in the FGF-ETV-SHH inhibitory feedback loop that dictates branching periodicity.

BMPs are direct triggers of interdigital programmed cell death

During vertebrate embryogenesis the interdigital mesenchyme is removed by programmed cell death (PCD), except in species with webbed limbs. Although bone morphogenetic proteins (BMPs) have long been known to be players in this process, it is unclear if they play a direct role in the interdigital mesenchyme or if they only act indirectly, by affecting fibroblast growth factor (FGF) signaling. A series of genetic studies have shown that BMPs act indirectly by regulating the withdrawal of FGF activity from the apical ectodermal ridge (AER); this FGF activity acts as a cell survival factor for the underlying mesenchyme. Other studies using exogenous factors to inhibit BMP activity in explanted mouse limbs suggest that BMPs do not act directly in the mesenchyme. To address the question of whether BMPs act directly, we used an interdigit-specific Cre line to inactivate several genes that encode components of the BMP signaling pathway, without perturbing the normal downregulation of AER-FGF activity. Of three Bmps expressed in the interdigital mesenchyme, Bmp7 is necessary for PCD, but Bmp2 and Bmp4 both have redundant roles, with Bmp2 being the more prominent player. Removing BMP signals to the interdigit by deleting the receptor gene, Bmpr1a, causes a loss of PCD and syndactyly, thereby unequivocally proving that BMPs are direct triggers of PCD in this tissue. We present a model in which two events must occur for normal interdigital PCD: the presence of a BMP death trigger and the absence of an FGF survival activity. We demonstrate that neither event is required for formation of the interdigital vasculature, which is necessary for PCD. However, both events converge on the production of reactive oxygen species that activate PCD.

Fgf3-Fgf4-cis: A new mouse line for studying Fgf functions during mouse development

The fibroblast growth factor (FGF) family consists of 22 ligands in mice and humans. FGF signaling is vital for embryogenesis and, when dysregulated, can cause disease. Loss-of-function genetic analysis in the mouse has been crucial for understanding FGF function. Such analysis has revealed that multiple Fgfs sometimes function redundantly. Exploring such redundancy between Fgf3 and Fgf4 is currently impossible because both genes are located on chromosome 7, about 18.5 kb apart, making the frequency of interallelic cross-over between existing mutant alleles too infrequent to be practicable. Therefore, we retargeted Fgf3 and Fgf4 in cis, generating an Fgf3 null allele and a conditional Fgf4 allele, subject to Cre inactivation. To increase the frequency of cis targeting, we used an F1 embryonic stem cell line that contained 129/SvJae (129) and C57BL/6J (B6) chromosomes and targeting constructs isogenic to the 129 chromosome. We confirmed cis targeting by assaying for B6/129 allele-specific single-nucleotide polymorphisms. We demonstrated the utility of the Fgf3(Δ)-Fgf4(flox)-cis mouse line by showing that the caudal axis extension defects found in the Fgf3 mutants worsen when Fgf4 is also inactivated. This Fgf3(Δ)-Fgf4(flox)-cis line will be useful to study redundancy of these genes in a variety of tissues and stages in development.

HIV-Infected Patient Knowledge, Attitudes, and Beliefs Regarding the Affordable Care Act

We evaluated patient knowledge, attitudes, and beliefs regarding changes present with the Affordable Care Act (ACA). HIV-infected adults attending an academic medical center HIV clinic in Omaha, Nebraska were asked to complete a self-administered survey between November 2013 and March 2014. Information collected included demographics, knowledge regarding healthcare reform policies, as well as attitudes and beliefs regarding the potential impact of the ACA on patient access to healthcare. Basic descriptive statistics were used to assess demographic characteristics of respondents and outcomes of interest. Chi-square tests were used for comparisons of interest among participants; some trends were evaluated with Cochran-Armitage trend tests. Four hundred and six patients completed the questionnaire. Of the respondents 90% were between the ages of 27 and 64, 61% were white, 27% had no health insurance, and 21% reported that they felt they had or will eventually benefit from the ACA. The proportion who responded "I don't know" to this question decreased over the study period (p=0.036). Overall, 57% reported they do not believe that they are informed enough to make decisions about the ACA. In answering four knowledge-based questions, only 3% answered all of them correctly. Knowledge about the ACA was significantly associated with perception of benefit (p=0.018). HIV-infected patients are not well informed about the ACA and few perceive that they will benefit from healthcare reform. Targeted education and outreach are necessary to reduce the knowledge gap for this population that stands to benefit greatly from the ACA.

Whole genomes redefine the mutational landscape of pancreatic cancer

Pancreatic cancer remains one of the most lethal of malignancies and a major health burden. We performed whole-genome sequencing and copy number variation (CNV) analysis of 100 pancreatic ductal adenocarcinomas (PDACs). Chromosomal rearrangements leading to gene disruption were prevalent, affecting genes known to be important in pancreatic cancer (TP53, SMAD4, CDKN2A, ARID1A and ROBO2) and new candidate drivers of pancreatic carcinogenesis (KDM6A and PREX2). Patterns of structural variation (variation in chromosomal structure) classified PDACs into 4 subtypes with potential clinical utility: the subtypes were termed stable, locally rearranged, scattered and unstable. A significant proportion harboured focal amplifications, many of which contained druggable oncogenes (ERBB2, MET, FGFR1, CDK6, PIK3R3 and PIK3CA), but at low individual patient prevalence. Genomic instability co-segregated with inactivation of DNA maintenance genes (BRCA1, BRCA2 or PALB2) and a mutational signature of DNA damage repair deficiency. Of 8 patients who received platinum therapy, 4 of 5 individuals with these measures of defective DNA maintenance responded.

Effect of alendronate on post-traumatic osteoarthritis induced by anterior cruciate ligament rupture in mice

Introduction

Previous studies in animal models of osteoarthritis suggest that alendronate (ALN) has antiresorptive and chondroprotective effects, and can reduce osteophyte formation. However, these studies used non-physiologic injury methods, and did not investigate early time points during which bone is rapidly remodeled prior to cartilage degeneration. The current study utilized a non-invasive model of knee injury in mice to investigate the effect of ALN treatment on subchondral bone changes, articular cartilage degeneration, and osteophyte formation following injury.

Methods

Non-invasive knee injury via tibial compression overload or sham injury was performed on a total of 90 mice. Mice were treated with twice weekly subcutaneous injections of low-dose ALN (40 μg/kg/dose), high-dose ALN (1,000 μg/kg/dose), or vehicle, starting immediately after injury until sacrifice at 7, 14 or 56 days. Trabecular bone of the femoral epiphysis, subchondral cortical bone, and osteophyte volume were quantified using micro-computed tomography (μCT). Whole-joint histology was performed at all time points to analyze articular cartilage and joint degeneration. Blood was collected at sacrifice, and serum was analyzed for biomarkers of bone formation and resorption.

Results

μCT analysis revealed significant loss of trabecular bone from the femoral epiphysis 7 and 14 days post-injury, which was effectively prevented by high-dose ALN treatment. High-dose ALN treatment was also able to reduce subchondral bone thickening 56 days post-injury, and was able to partially preserve articular cartilage 14 days post-injury. However, ALN treatment was not able to reduce osteophyte formation at 56 days post-injury, nor was it able to prevent articular cartilage and joint degeneration at this time point. Analysis of serum biomarkers revealed an increase in bone resorption at 7 and 14 days post-injury, with no change in bone formation at any time points.

Conclusions

High-dose ALN treatment was able to prevent early trabecular bone loss and cartilage degeneration following non-invasive knee injury, but was not able to mitigate long-term joint degeneration. These data contribute to understanding the effect of bisphosphonates on the development of osteoarthritis, and may support the use of anti-resorptive drugs to prevent joint degeneration following injury, although further investigation is warranted.

Baptisia poisoning: a new and toxic look-alike in the neighborhood

BACKGROUND

Baptisia is commonly found in residential gardens as an ornamental plant, in municipal "rain gardens" for water control, as well as in native and restored prairie habitat. Cytisine, an alkaloid with nicotinic acetylcholine receptor agonist properties, is a component of Baptisia.

CASE REPORT

Two patients poisoned after simultaneously ingesting Baptisia plant material are presented. In addition to findings of generalized nicotinic agonist toxicity, including generalized weakness and gastrointestinal symptoms, profound ataxia was present in both, consistent with recently described nicotinic subunit activity in the cerebellum. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Baptisia, a native prairie plant commonly found in restored prairie habitats and public spaces, has striking "look-alike" characteristics, in its immature state, to asparagus. As future exposures by foraging citizens will be likely, awareness of this relationship and the toxic manifestations of cytisine will be useful.