EIF4A3 deficient human iPSCs and mouse models demonstrate neural crest defects that underlie Richieri-Costa-Pereira syndrome.

Biallelic loss-of-function mutations in the RNA-binding protein EIF4A3 cause Richieri-Costa-Pereira syndrome (RCPS), an autosomal recessive condition mainly characterized by craniofacial and limb malformations. However, the pathogenic cellular mechanisms responsible for this syndrome are entirely unknown. Here, we used two complementary approaches, patient-derived induced pluripotent stem cells (iPSCs) and conditional Eif4a3 mouse models, to demonstrate that defective neural crest cell (NCC) development explains RCPS craniofacial abnormalities. RCPS iNCCs have decreased migratory capacity, a distinct phenotype relative to other craniofacial disorders. Eif4a3 haploinsufficient embryos presented altered mandibular process fusion and micrognathia, thus recapitulating the most penetrant phenotypes of the syndrome. These defects were evident in either ubiquitous or NCC-specific Eif4a3 haploinsufficient animals, demonstrating an autonomous requirement of Eif4a3 in NCCs. Notably, RCPS NCC-derived mesenchymal stem-like cells (nMSCs) showed premature bone differentiation, a phenotype paralleled by premature clavicle ossification in Eif4a3 haploinsufficient embryos. Likewise, nMSCs presented compromised in vitro chondrogenesis, and Meckel's cartilage was underdeveloped in vivo. These findings indicate novel and essential requirements of EIF4A3 for NCC migration and osteochondrogenic differentiation during craniofacial development. Altogether, complementary use of iPSCs and mouse models pinpoint unique cellular mechanisms by which EIF4A3 mutation causes RCPS, and provide a paradigm to study craniofacial disorders.

Ergonomic comparison of laparoscopic hand instruments in a single site surgery simulator with novices.

BACKGROUND: Single-site surgery improves cosmesis but increases procedural difficulty. Enhanced instruments could improve procedural efficiency leading to better patient outcomes. MATERIAL AND METHODS: One pair of non-articulating (straight) and two different pairs of articulating laparoscopic instruments were evaluated using a peg-transfer surgical task simulator by premedical college students. The instruments were comparatively tested using task performance measures, ergonomic measures, and participant questionnaires. RESULTS: The straight instrument produced significantly higher task performance scores and lower task times compared to both articulating instruments (p < 0.05). The straight instrument required less muscle activation and less wrist deviation than the articulating instruments to perform the same task. Participants rated the straight instrument significantly easier to use and less difficult to complete the task than with either articulating instrument (p < 0.05 for both). CONCLUSIONS: This exploratory study suggests that novices have difficulty using articulating instruments and perform better using straight laparoscopic instruments when first attempting LESS surgical tasks. Although a study with post-graduate medical trainees is needed to confirm these results, trainees should initially practice LESS with non-articulating instruments to gain proficiency at basic laparoscopic tasks. Additionally, redesigning articulating instruments to specifically address the spatial constraints and learning curve of LESS may also improve trainee performance and instrument usability.

The EJC component Magoh regulates proliferation and expansion of neural crest-derived melanocytes.

Melanoblasts are a population of neural crest-derived cells that generate the pigment-producing cells of our body. Defective melanoblast development and function underlies many disorders including Waardenburg syndrome and melanoma. Understanding the genetic regulation of melanoblast development will help elucidate the etiology of these and other neurocristopathies. Here we demonstrate that Magoh, a component of the exon junction complex, is required for normal melanoblast development. Magoh haploinsufficient mice are hypopigmented and exhibit robust genetic interactions with the transcription factor, Sox10. These phenotypes are caused by a marked reduction in melanoblast number beginning at mid-embryogenesis. Strikingly, while Magoh haploinsufficiency severely reduces epidermal melanoblasts, it does not significantly affect the number of dermal melanoblasts. These data indicate Magoh impacts melanoblast development by disproportionately affecting expansion of epidermal melanoblast populations. We probed the cellular basis for melanoblast reduction and discovered that Magoh mutant melanoblasts do not undergo increased apoptosis, but instead are arrested in mitosis. Mitotic arrest is evident in both Magoh haploinsufficient embryos and in Magoh siRNA treated melanoma cell lines. Together our findings indicate that Magoh-regulated proliferation of melanoblasts in the dermis may be critical for production of epidermally-bound melanoblasts. Our results point to a central role for Magoh in melanocyte development.

First-Order Estimates of Coastal Bathymetry in Ilulissat and Naajarsuit Fjords, Greenland, from Remotely Sensed Iceberg Observations.

Warm water masses circulating at depth off the coast of Greenland play an important role in controlling rates of mass loss from the Greenland Ice Sheet through feedbacks associated with the melting of marine glacier termini. The ability of these warm waters to reach glacier termini is strongly controlled by fjord bathymetry, which was unmapped for the majority of Greenland's fjords until recently. In response to the need for bathymetric measurements in previously uncharted areas, we developed two companion methods to infer fjord bathymetry using icebergs as depth sounders. The main premise of our methods centers around the idea that deep-drafted icebergs will become stranded in shallow water such that estimates of iceberg surface elevation can be used to infer draft, and thus water depth, under the assumption of hydrostatic equilibrium. When and where available, surface elevations of icebergs stranded on bathymetric highs were extracted from digital elevation models (DEMs) and converted to estimates of iceberg draft. To expand the spatial coverage of our inferred water depths beyond the DEM footprints, we used the DEMs to construct characteristic depth-width ratios and then inferred depths from satellite imagery-derived iceberg widths. We tested and applied the methods in two fjord systems in western Greenland with partially constrained bathymetry, Ilulissat Isfjord and Naajarsuit Fjord, to demonstrate their utility for inferring bathymetry using remote sensing datasets. Our results show that while the uncertainties associated with the methods are high (up to ±93 m), they provide critical first-order constraints on fjord bathymetry.

Neutropenic Enterocolitis in a Pediatric Heart Transplant Recipient on Multiple Immunosuppressants.

Neutropenic enterocolitis (NE) historically primarily affects pediatric patients with leukemia who are undergoing chemotherapy or who have recently received bone marrow transplants. Although a few case reports have shown NE occurring outside of this typical population, to our knowledge, this is the first published case of NE occurring in the setting of pediatric heart transplant. This patient was diagnosed several months after pediatric heart transplant, with radiographs showing evidence of pneumatosis intestinalis. Although NE does not typically affect solid organ transplant patients, this patient had a variety of risk factors that may have predisposed her to development of NE such as severe neutropenia, supratherapeutic tacrolimus level, immunosuppression with cytotoxic agents, and elevated Epstein-Barr viral load. Fortunately, this patient improved with bowel rest, fluids, antibiotics, and alteration of her immunosuppressive regimen. However, NE can be fatal, and thus it is an important condition to consider, even in patients without leukemia or on chemotherapeutic regimens.

Anti-inflammatory agents attenuate the passive responses of guinea pig pups: evidence for stress-induced sickness behavior during maternal separation.

A previous study found that intracerebroventricular (ICV) infusion of 25 microg of alpha-MSH reduced the passive responses (crouched stance, eye-closing, piloerection) of guinea pig pups during a 3-h isolation in a novel environment. Because alpha-MSH has broad anti-inflammatory properties, the results suggested that proinflammatory factors play a role in mediating the behavior of isolated infants. The present study further investigated this possibility. In Experiment 1, injection of lipopolysacchride (LPS) increased the number of 60-s intervals in which pups expressed the same three responses during a 1-h test, and ICV infusion of alpha-MSH significantly reduced the effect of LPS on crouching and piloerection. In Experiment 2, the prostaglandin synthesis inhibitor indomethacin (10 mg/kg) reduced the number of 60-s intervals in which pups exhibited both crouching and the full suite of passive responses during a 3-h isolation in a novel environment. Together these results provide further support for the hypothesis that the passive behaviors exhibited during prolonged isolation are "stress-induced sickness behaviors" mediated by proinflammatory factors.

Prolonged Mitosis of Neural Progenitors Alters Cell Fate in the Developing Brain.

Embryonic neocortical development depends on balanced production of progenitors and neurons. Genetic mutations disrupting progenitor mitosis frequently impair neurogenesis; however, the link between altered mitosis and cell fate remains poorly understood. Here we demonstrate that prolonged mitosis of radial glial progenitors directly alters neuronal fate specification and progeny viability. Live imaging of progenitors from a neurogenesis mutant, Magoh(+/-), reveals that mitotic delay significantly correlates with preferential production of neurons instead of progenitors, as well as apoptotic progeny. Independently, two pharmacological approaches reveal a causal relationship between mitotic delay and progeny fate. As mitotic duration increases, progenitors produce substantially more apoptotic progeny or neurons. We show that apoptosis, but not differentiation, is p53 dependent, demonstrating that these are distinct outcomes of mitotic delay. Together our findings reveal that prolonged mitosis is sufficient to alter fates of radial glia progeny and define a new paradigm to understand how mitosis perturbations underlie brain size disorders such as microcephaly.

Epigenetic states of cells of origin and tumor evolution drive tumor-initiating cell phenotype and tumor heterogeneity.

A central confounding factor in the development of targeted therapies is tumor cell heterogeneity, particularly in tumor-initiating cells (TIC), within clinically identical tumors. Here, we show how activation of the Sonic Hedgehog (SHH) pathway in neural stem and progenitor cells creates a foundation for tumor cell evolution to heterogeneous states that are histologically indistinguishable but molecularly distinct. In spontaneous medulloblastomas that arise in Patched (Ptch)(+/-) mice, we identified three distinct tumor subtypes. Through cell type-specific activation of the SHH pathway in vivo, we determined that different cells of origin evolved in unique ways to generate these subtypes. Moreover, TICs in each subtype had distinct molecular and cellular phenotypes. At the bulk tumor level, the three tumor subtypes could be distinguished by a 465-gene signature and by differential activation levels of the ERK and AKT pathways. Notably, TICs from different subtypes were differentially sensitive to SHH or AKT pathway inhibitors, highlighting new mechanisms of resistance to targeted therapies. In summary, our results show how evolutionary processes act on distinct cells of origin to contribute to tumoral heterogeneity, at both bulk tumor and TIC levels.

Comparative usability testing of conventional and single incision laparoscopic surgery devices.

OBJECTIVE: The objective was to perform competitive usability testing to assess the user experience of conventional laparoscopic and laparoendoscopic single-site surgery (LESS) devices. BACKGROUND: Recent advancements in single-incision instrumentation have created more interest in and usage of LESS. However, neither LESS nor its novel multichannel access devices have been thoroughly studied. METHOD: Using a simulation test bed and standardized laparoscopic surgery task, the user experience of three commercially available LESS devices was compared to conventional laparoscopic ports based on time on task, errors, task success, and perceived ease of use. RESULTS: There were no significant differences between devices for time on task, errors, or task success (p > .05). For all devices, there were significantly more recoverable than unrecoverable errors, and errors occurred more frequently during the second phase of the task when the dominant hand was more active (p < .0001). Conventional laparoscopy was rated as easier to use than were the LESS devices (p < .01). CONCLUSION: Device performance of a basic laparoscopic task was similar in both conventional laparoscopy and LESS. Each of the LESS devices facilitated efficient and accurate aiming and grasping movements compared to conventional laparoscopy. Further investigation of human factors and ergonomics of LESS is needed to further develop, evaluate, and refine single-site surgery technologies to create a user experience equivalent to conventional laparoscopy. APPLICATION: Competitive usability testing of medical devices yields objective performance data that can be used to inform purchase decisions and future device design improvements.

Notch1-induced brain tumor models the sonic hedgehog subgroup of human medulloblastoma.

While activation of the Notch pathway is observed in many human cancers, it is unknown whether elevated Notch1 expression is sufficient to initiate tumorigenesis in most tissues. To test the oncogenic potential of Notch1 in solid tumors, we expressed an activated form of Notch1 (N1ICD) in the developing mouse brain. N1ICD;hGFAP-cre mice were viable but developed severe ataxia and seizures, and died by weaning age. Analysis of transgenic embryo brains revealed that N1ICD expression induced p53-dependent apoptosis. When apoptosis was blocked by genetic deletion of p53, 30% to 40% of N1ICD;GFAP-cre;p53(+/-) and N1ICD;GFAP-cre;p53(-/-) mice developed spontaneous medulloblastomas. Interestingly, N1ICD-induced medulloblastomas most closely resembled the sonic hedgehog subgroup of human medulloblastoma at the molecular level. Surprisingly, N1ICD-induced tumors do not maintain high levels of the Notch pathway gene expression, except for Notch2, showing that initiating oncogenic events may not be decipherable by analyzing growing tumors in some cases. In summary, this study shows that Notch1 has an oncogenic potential in the brain when combined with other oncogenic hits, such as p53 loss, and provides a novel mouse model of medulloblastoma. Cancer Res; 73(17); 5381-90. ©2013 AACR.

Brief exposure to the biological mother "potentiates" the isolation behavior of precocial Guinea pig pups.

When isolated rat pups are briefly reunited with a lactating female, her subsequent removal leads to a dramatic increase in the emission of ultrasonic vocalizations, but not other behaviors. Whether this socially induced augmentation of isolation behavior (i.e., "potentiation") is characteristic only of altricial rodents is not known. Therefore, we examined precocial guinea pig pups in a potentiation paradigm. Ten-day-old guinea pigs were isolated in a test cage for 10 min, at which time they were then placed into a second cage for 5 min that either contained a companion or, for controls, was empty. Pups were then isolated again in the test cage for a second 10-min period. Control pups showed a significant reduction in vocalizing and locomotor activity from the first to second isolation period. Exposure to the biological mother prevented the decline in both behaviors (Experiment 1), whereas exposure to a familiar littermate (Experiment 2) had no effect, and exposure to an unfamiliar lactating female (Experiment 3) had only a minimal effect on locomotor activity. The results show that potentiation of isolation behaviors is not limited to altricial rodents, and suggest that specific characteristics of the effect (i.e., its magnitude, the specific behaviors affected, and the selectivity of the response to particular social partners) varies with the abilities and requirements of the young, as well as the behavioral ecology of the species in question.