A Novel Macroglossia Severity Index for Beckwith-Wiedemann Syndrome.

OBJECTIVE/ SUMMARY BACKGROUND DATA: We propose the first classification scheme for macroglossia in patients with Beckwith-Wiedemann Syndrome (BWS), the BWS Index of macroGlossia (BIG). METHODS: Patients with molecularly confirmed BWS seen from 2004-2023 were included to develop this system. Relationships among BIG scores, tongue reduction surgery, BWS clinical score, percent mosaicism, and polysomnography findings were examined. RESULTS: Patients were classified from BIG0 to BIG3. BIG0 includes those without macroglossia; BIG1 includes those with macroglossia not protruding beyond the teeth/alveolus; BIG2 includes those with tongue protrusion past the teeth/alveolus to the lips but that can be contained within the mouth; and BIG3 includes those with tongues that protrude beyond the teeth/alveolus and lips but that cannot be closed within the mouth. Of the 459 patients with molecularly confirmed BWS, 266 (58.0%) patients were scored. One hundred and eleven (41.7%) were BIG0, 44 (16.5%) were BIG1, 90 (33.8%) were BIG2, and 21 (7.9%) were BIG3. As scores increased, patients had an increased incidence of tongue reduction surgery (BIG0: 0% versus BIG1: 20.5% versus BIG2: 51.1% versus BIG3: 100%; r=0.66, P <0.01). Higher BIG scores were associated with elevated BWS clinical scores (r=0.68, P <0.01) and increased tissue mosaicism (r=0.50, P <0.01) as well as trends towards worse obstructive apnea-hypopnea indices (r=0.29, P =0.02) and lower SpO 2 nadirs (r=-0.29, P =0.02). CONCLUSION: In this large series of patients with Beckwith-Wiedemann Syndrome, increased BIG score correlates with undergoing tongue reduction surgery and increased phenotypic severity. Adoption of the BIG scoring system may facilitate communication and risk stratification across institutions.

Columbia-Suicide Severity Rating Scale (C-SSRS) Reveals High Rates of Suicidality in 602 Patients With Cleft and Craniofacial Conditions.

INTRODUCTION: Little is known about rates of suicidal ideation and behavior among youth with cleft lip and/or palate (CLP) and other craniofacial conditions. METHODS: Records of patients ages 6 and older who were administered the Columbia-Suicide Severity Rating Scale (C-SSRS) Lifetime Version during routine multidisciplinary cleft or craniofacial team visits between 2019 and 2023 were examined. Demographics information, C-SSRS data, and diagnoses were assessed with statistics including t tests, the Fisher exact test, and odds ratios. RESULTS: A total of 1140 C-SSRS questionnaires across 602 (433 CLP and 169 craniofacial) patients with an average age of 11.2±3.7 years were included. Eighty-four (13.6%) patients endorsed lifetime suicidal ideation, 9 (1.5%) had at least one instance of suicidal behavior, 30 (5.0%) endorsed nonsuicidal self-injury, and 2 (0.3%) engaged in self-injurious behavior. Compared with CLP, those with other craniofacial conditions had similar odds of endorsing suicidal ideation and behavior ( P ≥0.05). Compared with those with isolated cleft palates, CLP had greater odds of endorsing suicidal ideation and behavior, though those differences were not significant ( P ≥0.05). Incidence of suicidality was unchanged before, during, and after the COVID-19 pandemic ( P ≥0.05). Dividing patients by sex or insurance type revealed no difference in suicidality ( P ≥0.05). CONCLUSION: Patients with CLP and craniofacial conditions have a high incidence of suicidal ideation and behavior, though levels are similar between these groups. Suicidality in these patients was not negatively impacted by the COVID-19 pandemic. Early identification of safety risks and psychosocial challenges through regular screening can facilitate connection with appropriate clinical interventions.

The Timing of Acute and Late Complications Following Mastectomy and Implant-based Reconstruction.

BACKGROUND/OBJECTIVE: Implant-based breast reconstruction is a common plastic surgery procedure with well-documented clinical outcomes. Despite this, the natural history and timing of key complication endpoints are not well described. The goal of this study is to determine when patients are most likely to experience specific adverse events after implant-based reconstruction. METHODS: Retrospective consecutive series of patients who received mastectomy and implant-based reconstruction over a 6-year period were included. Complications and unfavorable outcomes including hematoma, seroma, wound infection, skin flap necrosis, capsular contracture, implant rippling, and implant loss were identified. A time-to-event analysis was performed and Cox regression models identified patient and treatment characteristics associated with each outcome. RESULTS: Of 1473 patients and 2434 total reconstructed breasts, 785 complications/unfavorable outcomes were identified. The 12-month cumulative incidence of hematoma was 1.4%, seroma: 4.3%, infection: 3.2%, skin flap necrosis: 3.9%, capsular contracture: 5.7%, implant rippling: 7.1%, and implant loss: 3.9%. In the analysis, 332/785 (42.3%) complications occurred within 60 days of surgery; 94% of hematomas, 85% of skin necrosis events, and 75% of seromas occurred during this period. Half of all infections and implant losses also occurred within 60 days. Of the remaining complications, 94% of capsular contractures and 93% of implant rippling occurred >60 days from surgery. CONCLUSIONS: Complications following mastectomy and implant-based reconstruction exhibit a discrete temporal distribution. These data represent the first comprehensive study of the timing of adverse events following implant-based reconstruction. These findings are immediately useful to guide postoperative care, follow-up, and clinical trial design.

An Irf6-Esrp1/2 regulatory axis controls midface morphogenesis in vertebrates.

Irf6 and Esrp1 are important for palate development across vertebrates. In zebrafish, we found that irf6 regulates the expression of esrp1 We detailed overlapping Irf6 and Esrp1/2 expression in mouse orofacial epithelium. In zebrafish, irf6 and esrp1/2 share expression in periderm, frontonasal ectoderm and oral epithelium. Genetic disruption of irf6 and esrp1/2 in zebrafish resulted in cleft of the anterior neurocranium. The esrp1/2 mutant also developed cleft of the mouth opening. Lineage tracing of cranial neural crest cells revealed that the cleft resulted not from migration defect, but from impaired chondrogenesis. Analysis of aberrant cells within the cleft revealed expression of sox10, col1a1 and irf6, and these cells were adjacent to krt4+ and krt5+ cells. Breeding of mouse Irf6; Esrp1; Esrp2 compound mutants suggested genetic interaction, as the triple homozygote and the Irf6; Esrp1 double homozygote were not observed. Further, Irf6 heterozygosity reduced Esrp1/2 cleft severity. These studies highlight the complementary analysis of Irf6 and Esrp1/2 in mouse and zebrafish, and identify a unique aberrant cell population in zebrafish expressing sox10, col1a1 and irf6 Future work characterizing this cell population will yield additional insight into cleft pathogenesis.

FaceBase 3: analytical tools and FAIR resources for craniofacial and dental research.

The FaceBase Consortium was established by the National Institute of Dental and Craniofacial Research in 2009 as a 'big data' resource for the craniofacial research community. Over the past decade, researchers have deposited hundreds of annotated and curated datasets on both normal and disordered craniofacial development in FaceBase, all freely available to the research community on the FaceBase Hub website. The Hub has developed numerous visualization and analysis tools designed to promote integration of multidisciplinary data while remaining dedicated to the FAIR principles of data management (findability, accessibility, interoperability and reusability) and providing a faceted search infrastructure for locating desired data efficiently. Summaries of the datasets generated by the FaceBase projects from 2014 to 2019 are provided here. FaceBase 3 now welcomes contributions of data on craniofacial and dental development in humans, model organisms and cell lines. Collectively, the FaceBase Consortium, along with other NIH-supported data resources, provide a continuously growing, dynamic and current resource for the scientific community while improving data reproducibility and fulfilling data sharing requirements.

Nasal Construction in Congenital Arhinia Due to Novel SMCHD1 Gene Variant.

Arhinia, or congenital absence of the nose, is an exceedingly rare anomaly caused by pathogenic variants in the gene SMCHD1 . Arhinia exhibits unique reconstructive challenges, as the midface is deficient in skeletal and soft tissue structures. The authors present 2 related patients with arhinia who harbor a novel SMCHD1 gene variant and illustrate their surgical midface and nasal construction. Targeted sequencing was carried out on DNA samples from the 2 affected patients, 1 anosmic and 1 healthy parent, to identify variants in exons 3 to 13 of SMCHD1 . The affected patients and anosmic parent were found to have a novel SMCHD1 gene variant p.E473V. A staged surgical approach was applied. First, both patients underwent a LeFort II osteotomy and distraction osteogenesis to improve the projection of the midfacial segment, followed by tissue expansion of the forehead, and nasal construction with a forehead flap that was placed over a costochondral framework derived from rib cartilage. The novel gene variant could guide future investigations on genetic pathways and molecular processes that underly the physiological and pathologic development of the nose. Further investigations on the variable expressivity ranging from anosmia to arhinia could improve clinical genetic screens for risk stratification of individuals with anosmia on passing on arhinia to their children. Due to the exceptional rarity and complexity of congenital arhinia, most surgical approaches are developed on a single-case basis. This case series, albeit limited to 2 cases, is the largest pedigree of such cases in the literature. It highlights key principles of a staged approach to nasal construction in arhinia and discusses nuances and improvements learned between both patients. It subsequently offers an optimized guide to this surgical strategy.

One-Year Experience of Same-Day Mastectomy and Breast Reconstruction Protocol.

BACKGROUND: The prevalence of same-day mastectomy with reconstruction has continued to increase across the United States in recent years. Prior studies have shown that same-day mastectomy with reconstruction leads to increased patient satisfaction and allows hospitals to use resources better. This study sought to evaluate the implementation of same-day mastectomy with a reconstruction recovery protocol for patients undergoing mastectomy at our institution. METHODS: Under an institutional review board-approved protocol, a retrospective cohort analysis compared patients who underwent mastectomy April 2016 through April 2017 with those who had mastectomy March 2020 through March 2021. Length of stay, postoperative intravenous (IV) opioid administration, safety end points, and cost were the main variables examined. RESULTS: The study compared 457 patients in 2016-2017 with 428 patients in 2020-2021. The median hospital length of stay decreased from 24.6 h in 2016-2017 to 5.5 h in 2020-2021 (p < 0.001). The percentage of patients requiring postoperative IV opioids decreased from 69.1 % in 2016-2017 to 50 % in 2020-2021 (p < 0.001). The rates of unplanned readmissions within 30 days after mastectomy did not differ between the two groups, with a rate of 3.7 % in 2016-2017 and a rate of 5.1 % in 2020-2021 (p = 0.30). Reducing the rate of overnight admissions after mastectomy by 65.8 % resulted in a cost reduction of 65.8 %. CONCLUSIONS: Implementation of same-day mastectomy with a reconstruction protocol across a large academic center and two satellite sites was a safe alternative to conventional mastectomy recovery plans.

The TFAP2A-IRF6-GRHL3 genetic pathway is conserved in neurulation.

Mutations in IRF6, TFAP2A and GRHL3 cause orofacial clefting syndromes in humans. However, Tfap2a and Grhl3 are also required for neurulation in mice. Here, we found that homeostasis of Irf6 is also required for development of the neural tube and associated structures. Over-expression of Irf6 caused exencephaly, a rostral neural tube defect, through suppression of Tfap2a and Grhl3 expression. Conversely, loss of Irf6 function caused a curly tail and coincided with a reduction of Tfap2a and Grhl3 expression in tail tissues. To test whether Irf6 function in neurulation was conserved, we sequenced samples obtained from human cases of spina bifida and anencephaly. We found two likely disease-causing variants in two samples from patients with spina bifida. Overall, these data suggest that the Tfap2a-Irf6-Grhl3 genetic pathway is shared by two embryologically distinct morphogenetic events that previously were considered independent during mammalian development. In addition, these data suggest new candidates to delineate the genetic architecture of neural tube defects and new therapeutic targets to prevent this common birth defect.

Postmastectomy Radiation Therapy on Permanent Implants or Tissue Expanders: Which is Better?

OBJECTIVES: This study evaluates complications and reconstructive failure rates in implant-based reconstruction with radiotherapy. BACKGROUND: Postmastectomy radiotherapy may adversely affect breast reconstructive outcomes. However, the comparative effect of radiotherapy on direct-to-implant versus tissue expander-implant reconstruction has not been examined. METHODS: Single institution retrospective review was performed and patients were followed 2 to 10 years. RESULTS: Of 1566 patients, 265 patients received radiation (149 immediate implants and 116 tissue expanders). Demographics were similar except more smokers in the expander group (7.7% vs 1.3%; P = 0.012). Patients who received radiation with an expander in place had overall more complications (32.8% vs 11.4%; P < 0.001), skin necrosis (10.3% vs 4.0%; P = 0.043), wound breakdown (9.5% vs 2.7%; P = 0.029), and infections (16.4% vs 4.03%; P = 0.001) leading to a higher rate of explantation (16.4% vs 4.0%; P < 0.001). A radiation boost likewise predicted complications [odds ratio (OR) 2.199, 95% confidence interval (CI) 1.154-4.188, P = 0.017]. When comparing reconstructive outcomes, radiated expanders had a higher failure rate (21.6% vs 11.4%; P = 0.025). Revision for capsular contracture was similar between the 2 cohorts (11.4% vs 11.2%; P = 0.959) as were revision rates for contour asymmetry and breast asymmetry. In our multivariable logistic regression analysis, radiation to the expander had a higher risk of reconstruction failure than radiation to the permanent implant (OR 2.020, 95% CI 1.010-4.037, P = 0.047). CONCLUSION: Most patients had successful implant-based reconstructions after mastectomy and radiotherapy. Our study showed radiotherapy after direct-to-implant breast reconstruction had a lower rate of complications and reconstructive failure compared to tissue expander-implant reconstruction.

Target coverage and cardiopulmonary sparing with the updated ESTRO-ACROP contouring guidelines for postmastectomy radiation therapy after breast reconstruction: a treatment planning study using VMAT and proton PBS techniques.

BACKGROUND: The European Society for Therapeutic Radiology and Oncology Advisory Committee in Radiation Oncology Practice (ESTRO-ACROP) recently released new contouring guidelines for postmastectomy radiation therapy (PMRT) after implant-based reconstruction (IBR). As compared to prior ESTRO guidelines, the new guidelines primarily redefined the chest wall (CW) target to exclude the breast prosthesis. In this study, we assessed the impact of these changes on treatment planning and dosimetric outcomes using volumetric-modulated arc therapy (VMAT) and proton pencil-beam scanning (PBS) therapy. METHODS: We performed a treatment planning study of 10 women with left-sided breast cancer who underwent PMRT after IBR. All target structures were delineated first using standard (ESTRO) breast contouring guidelines and then separately using the new (ESTRO-ACROP) guidelines. Standard organs-at-risk (OARs) and cardiac substructures were contoured. Four sets of plans were generated: (1) VMAT using standard ESTRO contours, (2) VMAT using new ESTRO-ACROP contours, (3) PBS using standard contours, and (4) PBS using new contours. RESULTS: VMAT plans using the new ESTRO-ACROP guidelines resulted in modest sparing of the left anterior descending coronary artery (LAD) (mean dose: 6.99 Gy standard ESTRO vs. 6.08 Gy new ESTRO-ACROP, p = 0.010) and ipsilateral lung (V20: 21.66% vs 19.45%, p = 0.017), but similar exposure to the heart (mean dose: 4.6 Gy vs. 4.3 Gy, p = 0.513), with a trend toward higher contralateral lung (V5: 31.0% vs 35.3%, p = 0.331) and CW doses (V5: 31.9% vs 35.4%, p = 0.599). PBS plans using the new guidelines resulted in further sparing of the heart (mean dose: 1.05 Gy(RBE) vs. 0.54 Gy(RBE), p < 0.001), nearly all cardiac substructures (LAD mean dose: 2.01 Gy(RBE) vs. 0.66 Gy(RBE), p < 0.001), and ipsilateral lung (V20: 16.22% vs 6.02%, p < 0.001). CONCLUSIONS: PMRT after IBR using the new ESTRO-ACROP contouring guidelines with both VMAT and PBS therapy is associated with significant changes in exposure to several cardiopulmonary structures.

Assessing the additional surgical risk of contralateral prophylactic mastectomy and immediate breast implant reconstruction.

INTRODUCTION: There has been a sharp rise in the rate of contralateral prophylactic mastectomy over the last decade, despite the low incidence of new primary cancers predicted for the contralateral breast. This study compares the postoperative complication rates between the diseased breast treated with mastectomy and the contralateral breast that underwent prophylactic mastectomy, followed by immediate bilateral breast implant reconstruction. We hypothesized that there will be no difference in postoperative outcomes between prophylactic and diseased groups, as the surgical approach would be comparable. METHODS: After IRB approval, a retrospective chart review identified consecutive unilateral breast cancer patients who underwent bilateral mastectomy and immediate breast reconstruction between May 2008 and May 2018 at a tertiary academic medical center. A paired sample t-test and a penalized logic regression model were constructed to identify relationships between breast laterality and outcomes. RESULTS: A total of 1117 patients with unilateral breast cancer who underwent bilateral mastectomy and immediate breast implant reconstruction were identified. Rates of capsular contracture and infection were significantly greater in the diseased breast, while rates of revision were significantly greater in the contralateral prophylactic breast. There were no statistically significant differences between breasts in rates of explant, skin flap necrosis or hematoma. When adjusted for confounding variables, a higher infection rate was observed in the diseased breast. CONCLUSION: This study detected significant differences in postoperative complication rates between the diseased and prophylactic breasts following bilateral mastectomy and immediate breast implant reconstruction. Postoperative complications occurred more frequently in the diseased breast compared with low rates of complications in the contralateral prophylactic breast. This information is helpful for preoperative decision making, as surgeons and patients carefully weigh the additional risks of contralateral prophylactic procedure.

Meta-analysis of prepectoral implant-based breast reconstruction: guide to patient selection and current outcomes.

PURPOSE:  This meta-analysis provides a large-scale comparison of prepectoral vs. subpectoral implant-based breast reconstruction, with primary outcomes of patient safety and efficacy. METHODS: Literature review was performed via PRISMA criteria, 33 studies met inclusion criteria for prepectoral review and 13 studies met inclusion criteria for meta-analysis. Patient characteristics and per-breast complications were collected. Data were analyzed using Cochrane RevMan and IBM SPSS. RESULTS: In 4692 breasts of 3014 patients that underwent prepectoral breast reconstruction, rippling was observed as the most common complication, followed by seroma and skin flap necrosis. Meta-analysis demonstrated statistically significant decrease in odds of skin flap necrosis and capsular contracture in prepectoral groups compared to subpectoral groups. Odds of infection, seroma, and hematoma were equal between the two groups. CONCLUSIONS: Prepectoral breast reconstruction has surged in popularity in recent years. This review and large-scale analysis corroborates current literature reporting a favorable safety profile with emphasis on patient selection. Variability in skin flap thickness and vascularity mandates thoughtful selection of patients whose overall health and intra-operative skin flap assessment can tolerate a muscle-sparing reconstruction.

High-Efficiency Same-Day Approach to Breast Reconstruction During the COVID-19 Crisis.

PURPOSE: As our hospitals conserve and re-allocate resources during the COVID-19 crisis, there is urgent need to determine how best to continue caring for breast cancer patients. During the time window before the COVID-19 critical peak and particularly thereafter, as hospitals are able to resume cancer operations, we anticipate that there will be great need to maximize efficiency to treat breast cancer. The goal of this study is to present a same-day protocol that minimizes resource utilization to enable hospitals to increase inpatient capacity, while providing care for breast cancer patients undergoing mastectomy and immediate breast reconstruction during the COVID-19 crisis. METHODS: IRB exempt patient quality improvement initiative was conducted to detail the operationalization of a novel same-day breast reconstruction protocol. Consecutive patients having undergone immediate breast reconstruction were prospectively enrolled between February and March of 2020 at Massachusetts General Hospital during the COVID-19 crisis. Peri-operative results and postoperative complications were summarized. RESULTS: Time interval from surgical closure to patient discharge was 5.02 ± 1.29 h. All patients were discharged home, with no re-admissions or emergency department visits. No postoperative complications were observed. CONCLUSION: This report provides an instruction manual to operationalize a same-day breast reconstruction protocol, to meet demands of providing appropriate cancer treatment during times of unprecedented resource limitations. Pre-pectoral implant-based breast reconstruction can be the definitive procedure or be used as a bridge to autologous reconstruction. Importantly, we hope this work will be helpful to our patients and community as we emerge from the COVID-19 pandemic.

Rapid functional analysis of computationally complex rare human IRF6 gene variants using a novel zebrafish model.

Large-scale sequencing efforts have captured a rapidly growing catalogue of genetic variations. However, the accurate establishment of gene variant pathogenicity remains a central challenge in translating personal genomics information to clinical decisions. Interferon Regulatory Factor 6 (IRF6) gene variants are significant genetic contributors to orofacial clefts. Although approximately three hundred IRF6 gene variants have been documented, their effects on protein functions remain difficult to interpret. Here, we demonstrate the protein functions of human IRF6 missense gene variants could be rapidly assessed in detail by their abilities to rescue the irf6 -/- phenotype in zebrafish through variant mRNA microinjections at the one-cell stage. The results revealed many missense variants previously predicted by traditional statistical and computational tools to be loss-of-function and pathogenic retained partial or full protein function and rescued the zebrafish irf6 -/- periderm rupture phenotype. Through mRNA dosage titration and analysis of the Exome Aggregation Consortium (ExAC) database, IRF6 missense variants were grouped by their abilities to rescue at various dosages into three functional categories: wild type function, reduced function, and complete loss-of-function. This sensitive and specific biological assay was able to address the nuanced functional significances of IRF6 missense gene variants and overcome many limitations faced by current statistical and computational tools in assigning variant protein function and pathogenicity. Furthermore, it unlocked the possibility for characterizing yet undiscovered human IRF6 missense gene variants from orofacial cleft patients, and illustrated a generalizable functional genomics paradigm in personalized medicine.

Roles of Wnt pathway genes wls, wnt9a, wnt5b, frzb and gpc4 in regulating convergent-extension during zebrafish palate morphogenesis.

The Wnt signaling pathway is crucial for tissue morphogenesis, participating in cellular behavior changes, notably during the process of convergent-extension. Interactions between Wnt-secreting and receiving cells during convergent-extension remain elusive. We investigated the role and genetic interactions of Wnt ligands and their trafficking factors Wls, Gpc4 and Frzb in the context of palate morphogenesis in zebrafish. We describe that the chaperon Wls and its ligands Wnt9a and Wnt5b are expressed in the ectoderm, whereas juxtaposed chondrocytes express Frzb and Gpc4. Using wls, gpc4, frzb, wnt9a and wnt5b mutants, we genetically dissected the Wnt signals operating between secreting ectoderm and receiving chondrocytes. Our analysis delineates that non-canonical Wnt signaling is required for cell intercalation, and that wnt5b and wnt9a are required for palate extension in the anteroposterior and transverse axes, respectively.

Improving surgical efficiency of immediate implant-based breast reconstruction following mastectomy.

PURPOSE: Traditionally, during a mastectomy with implant-based reconstruction, the surgical oncologist completes their operative procedure prior to the reconstructive surgeon entering the room. In this scenario, two separate instruments kits and tables are utilized. In our institution, we created a combined instrument kit for use by both surgical teams. We compared set-up and operative times for each process and the subsequent savings associated with this novel approach. METHODS: Sixty-eight patients undergoing mastectomy with implant-based reconstruction were divided into two groups-those who underwent the procedure with separate oncology and reconstructive kits and those who underwent the procedure with combined instrumentation. Set-up time, procedure time, and clinical outcome endpoints were compared. Costs associated with each process were estimated. RESULTS: Surgical set-up time was lower using the combined kit versus separate kits [mean for unilateral cases, 25.1 ± 9.6 min vs. 35.7 ± 10.4 min (p < 0.01) and mean for bilateral cases, 33.1 ± 10.3 min vs. 43.5 ± 9.9 min (p = 0.31)]. Procedure time was significantly lower using the combined kit versus separate kits [mean for unilateral cases, 156.2 ± 31.7 min vs. 172.1 ± 33.0 min (p < 0.05) and mean for bilateral cases, 207.3 ± 39.3 min vs. 228. 8 ± 42.7 min (p = 0.03)]. Post-operative outcomes were not significantly different between the two groups at 6 months post-surgery (p = 0.72). Due to a decrease in operating room utilization and costs associated with instrumentation, we estimated $134,396 to $206,621 with unilateral cases and a $289,167 to $465,967 in yearly savings with bilateral cases by using the combined process. CONCLUSION: Mastectomy with implant-based reconstruction utilizing combined instrumentation, with surgeons working simultaneously, led to decreased operating room utilization and costs without impacting clinical outcomes. Level of evidence II.

Drug-selective Anesthetic Insensitivity of Zebrafish Lacking γ-Aminobutyric Acid Type A Receptor ß3 Subunits.

BACKGROUND: Transgenic mouse studies suggest that γ-aminobutyric acid type A (GABAA) receptors containing ß3 subunits mediate important effects of etomidate, propofol, and pentobarbital. Zebrafish, recently introduced for rapid discovery and characterization of sedative-hypnotics, could also accelerate pharmacogenetic studies if their transgenic phenotypes reflect those of mammals. The authors hypothesized that, relative to wild-type, GABAA-ß3 functional knock-out (ß3) zebrafish would show anesthetic sensitivity changes similar to those of ß3 mice. METHODS: Clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9 mutagenesis was used to create a ß3 zebrafish line. Wild-type and ß3 zebrafish were compared for fertility, growth, and craniofacial development. Sedative and hypnotic effects of etomidate, propofol, pentobarbital, alphaxalone, ketamine, tricaine, dexmedetomidine, butanol, and ethanol, along with overall activity and thigmotaxis were quantified in 7-day postfertilization larvae using video motion analysis of up to 96 animals simultaneously. RESULTS: Xenopus oocyte electrophysiology showed that the wild-type zebrafish ß3 gene encodes ion channels activated by propofol and etomidate, while the ß3 zebrafish transgene does not. Compared to wild-type, ß3 zebrafish showed similar morphology and growth, but more rapid swimming. Hypnotic EC50s (mean [95% CI]) were significantly higher for ß3 versus wild-type larvae with etomidate (1.3 [1.0 to 1.6] vs. 0.6 [0.5 to 0.7] µM; P < 0.0001), propofol (1.1 [1.0 to 1.4] vs. 0.7 [0.6 to 0.8] µM; P = 0.0005), and pentobarbital (220 [190 to 240] vs. 130 [94 to 179] µM; P = 0.0009), but lower with ethanol (150 [106 to 213] vs. 380 [340 to 420] mM; P < 0.0001) and equivalent with other tested drugs. Comparing ß3 versus wild-type sedative EC50s revealed a pattern similar to hypnosis. CONCLUSIONS: Global ß3 zebrafish are selectively insensitive to the same few sedative-hypnotics previously reported in ß3 transgenic mice, indicating phylogenetic conservation of ß3-containing GABAA receptors as anesthetic targets. Transgenic zebrafish are potentially valuable models for sedative-hypnotic mechanisms research.

Distinct requirements of wls, wnt9a, wnt5b and gpc4 in regulating chondrocyte maturation and timing of endochondral ossification.

Formation of the mandible requires progressive morphologic change, proliferation, differentiation and organization of chondrocytes preceding osteogenesis. The Wnt signaling pathway is involved in regulating bone development and maintenance. Chondrocytes that are fated to become bone require Wnt to polarize and orientate appropriately to initiate the endochondral ossification program. Although the canonical Wnt signaling has been well studied in the context of bone development, the effects of non-canonical Wnt signaling in regulating the timing of cartilage maturation and subsequent bone formation in shaping ventral craniofacial structure is not fully understood.. Here we examined the role of the non-canonical Wnt signaling pathway (wls, gpc4, wnt5b and wnt9a) in regulating zebrafish Meckel's cartilage maturation to the onset of osteogenic differentiation. We found that disruption of wls resulted in a significant loss of craniofacial bone, whereas lack of gpc4, wnt5b and wnt9a resulted in severely delayed endochondral ossification. This study demonstrates the importance of the non-canonical Wnt pathway in regulating coordinated ventral cartilage morphogenesis and ossification.

Actin capping protein CAPZB regulates cell morphology, differentiation, and neural crest migration in craniofacial morphogenesis†.

CAPZB is an actin-capping protein that caps the growing end of F-actin and modulates the cytoskeleton and tethers actin filaments to the Z-line of the sarcomere in muscles. Whole-genome sequencing was performed on a subject with micrognathia, cleft palate and hypotonia that harbored a de novo, balanced chromosomal translocation that disrupts the CAPZB gene. The function of capzb was analyzed in the zebrafish model. capzb(-/-) mutants exhibit both craniofacial and muscle defects that recapitulate the phenotypes observed in the human subject. Loss of capzb affects cell morphology, differentiation and neural crest migration. Differentiation of both myogenic stem cells and neural crest cells requires capzb. During palate morphogenesis, defective cranial neural crest cell migration in capzb(-/-) mutants results in loss of the median cell population, creating a cleft phenotype. capzb is also required for trunk neural crest migration, as evident from melanophores disorganization in capzb(-/-) mutants. In addition, capzb over-expression results in embryonic lethality. Therefore, proper capzb dosage is important during embryogenesis, and regulates both cell behavior and tissue morphogenesis.

Generation and characterization of a zebrafish muscle specific inducible Cre line.

Zebrafish transgenic lines provide valuable insights into gene functions, cell lineages and cell behaviors during development. Spatiotemporal control over transgene expression is a critical need in many experimental approaches, with applications in loss- and gain-of-function expression, ectopic expression and lineage tracing experiments. The Cre/loxP recombination system is a powerful tool to provide this control and the demand for validated Cre and loxP zebrafish transgenics is high. One of the major challenges to widespread application of Cre/loxP technology in zebrafish is comparatively small numbers of established tissue-specific Cre or CreERT2 lines. We used Tol2-mediated transgenesis to generate Tg(CrymCherry;-1.9mylz2:CreERT2) which provides an inducible CreERT2 source driven by muscle-specific mylz2 promoter. The transgenic specifically labels the trunk and tail skeletal muscles. We assessed the temporal responsiveness of the transgenic by screening with a validated loxP reporter transgenic ubi:Switch. Further, we evaluated the recombination efficiency in the transgenic with varying concentrations of 4-OHT, for different induction time periods and at different stages of embryogenesis and observed that higher recombination efficiency is achieved when embryos are induced with 10 µM 4-OHT from 10-somites or 24 hpf till 48 or 72 hpf. The transgenic is an addition to currently available zebrafish transgenesis toolbox and a significant tool to advance muscle biology studies in zebrafish.