bluuebunny/crossref_metadata_2025 huggingface dataset:
Does Obesity Affect Outcomes in Hip Arthroscopy?
Authors: Gupta Asheesh , Redmond John M. , Hammarstedt Jon E. , Stake Christine E. , Domb Benjamin G.
Published: January 2015

Background:

Hip arthroscopy has gained popularity over the past decade, and its indications have broadened as newer techniques have been developed. However, there has been a paucity of literature evaluating the outcomes of hip arthroscopy in obese patients.

Purpose:

To compare 2-year clinical outcomes of obese patients undergoing primary hip arthroscopy with matched nonobese controls.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

From February 2008 to February 2012, data were collected prospectively on all obese patients undergoing primary hip arthroscopy. A matched-pair nonobese control group was selected at a 1:2 ratio. All patients were assessed pre- and postoperatively with 4 patient-reported outcome (PRO) measures: the modified Harris Hip Score, Non-Arthritic Hip Score, Hip Outcome Score–Activities of Daily Living, and Hip Outcome Score–Sport Specific Subscale. Pain was estimated on the visual analog scale, and satisfaction was measured on a scale from 0 to 10.

Results:

Sixty-two hips (62 patients) were included in the obese group and 124 hips (124 patients) in the control group. At preoperative baseline, the obese group had significantly lower PRO scores when compared with the control group. Both groups demonstrated statistically significant postoperative improvement in all scores ( P < .05). Absolute scores were significantly lower in the obese group for all PRO measures, pre- and postoperatively. However, the improvement (delta) in PRO scores from pre- to postoperative time was not significantly different between groups. The rate of conversion to total hip arthroplasty, the rate of revision, and the complication rate were not significantly different between the 2 groups; however, rates of conversion to total hip arthroplasty and revision tended to be twice as high in the obese patients, but the study was not powered for these 2 outcomes.

Conclusion:

Overall, obese patients had lower absolute PRO scores preoperatively and at 2-year follow-up. Both obese and nonobese patients demonstrated significant improvement in all PRO scores, and the change in scores were similar between groups. These results indicate that while obese patients may not have similar absolute scores after hip arthroscopy, they may show similar gains in improvement when compared with baseline. Hip arthroscopy appears to be a viable treatment option in the obese patient as long as expectations are adjusted accordingly.
Healing effect of a fibrin-based scaffold loaded with platelet lysate in full-thickness skin wounds
Authors: Losi Paola , Briganti Enrica , Sanguinetti Elena , Burchielli Silvia , Al Kayal Tamer , Soldani Giorgio
Published: January 2015

Chronic skin lesions are difficult to heal due to reduced levels and activity of endogenous growth factors. The platelet lysate, obtained by repeated freeze–thawing of platelet-enriched blood samples, is an easily attainable source of a wide range of growth factors and bioactive mediators involved in tissue repair. In this study, a bio-synthetic scaffold composed of poly(ether)urethane–polydimethylsiloxane material and fibrin was developed for platelet lysate delivery to chronic skin wounds. The kinetics release and the bioactivity of growth factors released from platelet lysate–loaded poly(ether)urethane–polydimethylsiloxane–fibrin scaffold were investigated, respectively, by enzyme-linked immunosorbent assay and a cell proliferation test using human fibroblasts. The in vitro experiments demonstrated that the platelet lysate–loaded poly(ether)urethane–polydimethylsiloxane–fibrin scaffold provides a sustained release of platelet derived growth factors. The cell growth in the presence of scaffold was comparable to those observed for the platelet lysate added to culture medium in free form, showing that the scaffold preparation process did not affect biological activity of growth factors. The effect of platelet lysate–loaded poly(ether)urethane–polydimethylsiloxane–fibrin scaffold on wound healing in genetically diabetic mouse (db/db) was also investigated. The application of the scaffold on full-thickness skin wounds significantly accelerated wound closure at day 15 post-surgery compared with control poly(ether)urethane–polydimethylsiloxane–fibrin scaffold (without platelet lysate) or a commercially available polyurethane film dressing. Histological analysis demonstrated an increased re-epithelialization, granulation tissue formation, and collagen deposition. The ability of the platelet lysate–loaded poly(ether)urethane–polydimethylsiloxane–fibrin scaffold to promote wound healing in vivo through simultaneous delivery of multiple active substances suggests its potential use for the treatment of diabetic foot ulcers.
Ultrasound‐Guided Nasogastric Feeding Tube Placement in Critical Care Patients
Authors: Gok Funda , Kilicaslan Alper , Yosunkaya Alper
Published: January 2015

Background: Nasogastric feeding tube (NGT) placement is a common practice performed in intensive care units (ICUs). Complications due to the improper placement of NGT are well known. In this prospective descriptive study, the effectiveness of ultrasound (US)–guided NGT placement was investigated. Materials and Methods: Fifty‐six mechanically ventilated patients monitored in the ICU were included. A linear US probe was transversely placed just cranial to the suprasternal notch, and the concentric layers of the esophagus were attempted to be viewed on the posterolateral side of the trachea (generally left) by shifting the probe. If the esophagus can be seen, an attempt was made to insert the NGT under real‐time visualization of ultrasonography. Furthermore, gastric placement of the NGT tip was confirmed with abdominal radiograph. Results: A total of 56 patients were included in the study. For 52 (92.8%), the NGT image was obtained during placement within the esophagus. For 3 (5.3%), the esophagus could not be seen by US, and NGT was placed blindly. For 1 patient, we could not detect passing of the NGT into the stomach despite the successful visualization of esophagus. In this patient, NGT was radiographically detected in the trachea after the procedure. Conclusion: This study revealed that passing of the NGT through the esophagus could be visualized at a high rate in real‐time US among ICU patients. These data suggest that ultrasonographic visualization of the upper esophagus during NGT insertion can be used as an adjuvant method for confirmation of correct placement.
Temperature measurement and theoretical analysis in high-speed grinding of hardened cold work die steel 9CrWMn
Authors: Wang Yan , Xu Jiuhua , Ding Wenfeng , Wang Qiuping , Lu Yang
Published: January 2015

Cold work die steel 9CrWMn is one kind of high tensile strength steel which is used to manufacture stamping mold, shearing mold, roller die, cold heading, and cold extrusion die mold. Because of its high hardness and toughness, 9CrWMn is difficult to be machined by conventional manufacturing techniques. A series of high-speed grinding experiments were conducted for cold work die steel 9CrWMn using cBN wheel to assess the grinding characteristics in terms of grinding temperature. The grinding temperatures were measured by using a grindable thermocouple technique. 9CrWMn-constantan is not a kind of standard thermocouple, calibrating the thermocouple from the comparison method field of vision was done in this work. A series of temperature field simulations of high speed grinding of cold work die steel 9CrWMn with abrasive grains were conducted in Deform-3D and mesh adaptive technology was adopted to get optimized results. This paper gives theoretical analyses that contribute to the temperature phenomena. The simulation results were consistent with the experimental temperature measurements.
Investigation of fatigue performance of low temperature alloys for liquefied natural gas storage tanks
Authors: Oh Dong-Jin , Lee Jae-Myung , Noh Byeong-Jae , Kim Wha-Soo , Ryuichi-Ando  , Toshiyuki-Matsumoto  , Kim Myung-Hyun
Published: January 2015

One of the most important issues associated with liquefied natural gas (LNG) storage tanks, such as LNG carrier cargo tanks and land LNG tanks, is their structural integrity. In order to ensure the operating life and safety of LNG storage tanks used under operating conditions such as thermal and cyclic loadings, the securing of safety evaluations for fatigue performance is considered to be of particular importance. There have been various efforts to reduce the production costs of LNG storage tanks, such as the optimum selection of materials and the development of new low temperature materials. This, the motivation of this study is to evaluate new material candidates for LNG storage tanks. This study begins with a comprehensive review of the characteristics of low temperature alloys such as SUS 304L, Invar, A5083 and 9% Ni steel that are widely used for LNG storage tanks. Then, the fatigue characteristics of a newly developed low temperature material, 7% nickel steel are investigated. Finally, the fatigue performance of 7% nickel steel is compared with that of 9% nickel steel.
Sliding of the load carrier in third-generation intramedullary nails for proximal femur fractures: An in vitro mechanical comparison study
Authors: Konstantinidis Lukas , Grünewald Heide , Hauschild Oliver , Schröter Steffen , Hirschmüller Anja , Südkamp Norbert Paul , Helwig Peter
Published: January 2015

Dynamic osteosynthesis of proximal femur fractures facilitates compression at the fracture site through distal glide of the femoral head load carrier in the intramedullary nail. Modern implants are currently designed according to diverse gliding principles. The aim of this study was to compare the sliding mechanisms of different types of nails. As in other similar mechanical studies the load patterns occurring around the femoral head load carrier and the intramedullary nail under full load were simulated for three different types of intramedullary nail - PFNA, Targon PFT and Trigen Intertan. The load necessary to trigger distal displacement of the femoral head implant in the nail was determined. The lengths of the load carriers were varied. For the three lengths of load carrier, mechanical testing showed that the Targon PFT started to slide at a significantly lower load compared to the other two implants. Comparison of the PFNA and Trigen Intertan in terms of load to dynamization for 77 mm carriers revealed a significantly lower load for the PFNA. Slide efficacy for the PFNA and the Trigen Intertan was found to improve as the length of the blade/screw was shortened. The dynamization properties of the Targon PFT with its cylindrical sliding mechanism, similar to the DHS, were far better compared to the PFNA and the Trigen Intertan that have more complex sliding actions. Since theoretical considerations indicate that a less efficient gliding action leads to a higher complication rate, implants of the next generation should be optimized in this regard.
Assessing patient satisfaction with a multidisciplinary gender dysphoria clinic in Melbourne
Authors: Erasmus Jaco , Bagga Harjit , Harte Fintan
Published: January 2015

Objectives:

The Gender Dysphoria Clinic in Melbourne, Australia, assessed patient outcome by focusing on patients’ subjective evaluation of the healthcare services they received through the clinic.

Methods:

A satisfaction survey, which was previously used in two established gender clinics in the US and UK, was adapted and then administered to consecutive patients who attended the Gender Dysphoria Clinic during a 1-month period.

Results:

A total of 127 surveys were available for analysis: 88% of patients reported being satisfied with the services they received. Patients’ perceived level of distress reduced significantly, following their involvement with the Gender Dysphoria Clinic. Feeling understood and heard in a non-judgmental manner by a specialist in the field of gender dysphoria was the most positive aspect of service provision. The most negative aspect of the clinic was a lengthy waiting list.

Conclusions:

Although the majority of trans-and-gender-diverse patients attending the Gender Dysphoria Clinic were satisfied with the service they received, there is a need to identify strategies to facilitate timely access to the clinic.
Monitoring and Alleviation of Symptom Occurrence and Severity Among Thai Children and Adolescents During Cancer Treatments
Authors: Williams Phoebe D. , Piamjariyakul Ubolrat , Shanberg Rachel , Williams Arthur R.
Published: January 2015

Background: Symptom monitoring and alleviation are important during pediatric cancer treatments. Aims: To examine the use of the Therapy-Related Symptom Checklist for Children (TRSC-C; Thai version) for reported occurrence, severity, and management of treatment-related symptoms within a cohort of Thai pediatric oncology patients/parents Method: Cross-sectional study; convenience sample: 100 parents of 71 male children/29 females, 63% with leukemia, 37%, other diagnoses; age-groups: <5 years, n = 33; 5 to 11 years, n = 44; 12 to 17 years, n = 25. Parents reported children’s symptom occurrence/severity on the TRSC-C; and complementary care methods on the Symptom Alleviation: Self-Care Methods and their symptom alleviation methods. All tools had good psychometric properties. Results: 18 symptoms on the 30-item TRSC-C occurred in 42% to 95% of children. Mean severity of symptoms was between 1.0 (“a bit”) and 2.0 (“quite a bit”); 5-month to 11-year-old children had higher (worse) TRSC-C total scores. Complementary care was used and reported. Conclusions: Monitoring of multiple symptoms with the TRSC-C and parental symptom alleviation helped children. Clinical Implications: Thai parents/patients need and accept assistance in monitoring/managing side effects of pediatric cancer therapy.
Developing Safety and Risk Assessment Tools and Training Materials
Authors: Spies Gloudina M. , Delport Catharina S. L. , le Roux Magdalena P.
Published: January 2015

Purpose:

This article presents the results of a two-phase dialogue between social work practitioners and researchers regarding the development and implementation of safety and risk assessment tools and training materials for social workers in the South African context.

Methods:

The first phase of the dialogue included interviews with 81 professionals to determine current practices in safety and risk assessment, resulting in the development of assessment tools and training materials. The second phase involved dialogue with 13 social workers who attended a workshop on the developed safety and risk assessment tools and who were able to implement the tools in practice.

Results:

A need for uniform safety and risk assessment tools and procedures was identified, and encouraging evidence indicated the effectiveness of the developed tools.

Discussion:

Constructive dialogue between practice and research was instrumental in developing and implementing safety and risk assessment tools and training materials for the South African context.
Treatment of Philadelphia chromosome-positive acute lymphoblastic leukemia in pregnancy
Authors: Mainor Candace B , Duffy Alison P , Atkins Kristin L , Kimball Amy S , Baer Maria R
Published: January 2015

BCR-ABL inhibitors administered in conjunction with chemotherapy have significantly improved outcomes in Philadelphia chromosome-positive acute lymphoblastic leukemia but, for patients diagnosed during pregnancy, data on risks to the fetus are limited. We report a woman treated with chemotherapy and imatinib mesylate who delivered a healthy baby at 30 weeks, and we discuss available data.
The piston problem in hyperelasticity with the stored energy in separable form
Authors: Ndanou Serge , Favrie Nicolas , Gavrilyuk Sergey
Published: January 2015

The piston problem for a hyperelastic hyperbolic conservative model where the stored energy is given in separable form is studied. The eigenfields corresponding to the hyperbolic system are of three types: linearly degenerate fields (corresponding to the contact characteristics), the fields which are genuinely nonlinear in the sense of Lax (corresponding to longitudinal waves), and, finally, nonlinear fields which are not genuinely nonlinear (corresponding to transverse waves). Taking the initial state free of stresses, we presented possible auto-similar solutions to the piston problem. In particular, we have shown that the equations admit transverse shock waves having a remarkable property: the solid density is decreasing through such a shock, it is thus a ‘rarefaction’ shock.
Coping with infertility: Comparison of coping mechanisms and psychological immune competence in fertile and infertile couples
Authors: Nagy Erika , Nagy Beáta Erika
Published: January 2015

This study compared coping strategies and psychological immunity of parents with a child conceived with assisted reproductive technology ( n = 84) and parents with a naturally conceived child ( n = 84) in a Hungarian fertility-age population. Results showed that in vitro fertilization parents are able to control their emotions in a better way than comparison couples. They interpret trials as challenges and consider themselves more worthy than the members of the control group. Our research confirms that consideration and management of psychological factors in treating infertility have an important preventive role to play.
Social work interventions on intimate partner violence against women in China
Authors: Tam Dora MY , Schleicher Katherine , Wu Wenmei , Kwok Siu-Ming , Thurston Wilfreda E , Dawson Myrna
Published: January 2015

Intimate Partner Violence (IPV) affects approximately one-fifth of women during their lifetime in China. However, limited studies have been conducted in China among women and service providers on IPV. The study reported in this article used an Ecological Model and the Capabilities Perspective integrated with the Advocacy Intervention Model as the theoretical framework for guiding the research and data analysis. This study was part of a participatory project to develop appropriate social work interventions in Guangzhou, China.

Findings

Twenty-one women who experienced IPV and 30 service providers were interviewed for their views on barriers to help-seeking processes, needs and concerns of this population, and recommendations for any changes. The results of this study clearly suggest that gender inequality is the root cause of IPV against women and prevents women from leaving a violent relationship.

Applications

The results suggest a number of needed changes at micro, meso, exo, and macro levels and the ways in which social workers can act as advocates for the changes in the context of Guangzhou.
Personality Traits and Correct Voting
Authors: Ha Shang E. , Lau Richard R.
Published: January 2015

Recent studies in political psychology report a significant association between personality traits and ordinary citizens’ attitudes and behaviors in the political arena. A growing body of literature examines the influence of personality on individuals’ attachment to a political party and vote choice in electoral settings. In line with these studies, we analyze the relationship between personality traits and “correct voting”, i.e., the extent to which citizens vote in accordance with their own preferences and values. Using a large-scale national survey fielded in the context of the 2008 presidential election, we find that, after controlling for well-known predictors of correct voting, some of personality traits not only exert a direct influence on correct voting, but also moderate the effect of strength of party identification, a well-established determinant of correct voting. These findings provide new evidence for the idea that individual differences such as dispositional personality traits are deeply intertwined with both vote choice and democratic representation.
Regarding the Credibility of Data Showing an Alleged Association of Cancer with Radiation from CT Scans
Authors: Socol Yehoshua , Welsh James S.
Published: January 2015

Computed tomography (CT) scans are of high clinical value as a diagnostic technique, and new applications continue to be identified. However, their application is challenged by emerging concerns regarding carcinogenesis from their radiation. Recent articles made a significant contribution to the above-mentioned concerns by reporting evidence for direct association of the radiation from CT scans with cancer. Such interpretation of the data has already been criticized; there is the possibility of reverse causation due to confounding factors. Nevertheless, such work has had a high impact, with one article being cited more than 300 times from the Web of Science Core Collection within 2 years. However, the data points on cancer relative risk versus CT dose in that article fit straight lines corresponding to the linear no-threshold hypothesis suspiciously well. Here, by applying rigorous statistical analysis, it is shown that the probability of the fit truly being that good or better is only 2%. The results of such studies therefore appear “too good to be true” and the credibility of their conclusions must be questioned.
Factor VIII gene variants and inhibitor risk in African American hemophilia A patients
Authors: Gunasekera Devi , Ettinger Ruth A. , Nakaya Fletcher Shelley , James Eddie A. , Liu Maochang , Barrett John C. , Withycombe Janice , Matthews Dana C. , Epstein Melinda S. , Hughes Richard J. , Pratt Kathleen P.
Published: January 2015

Key Points

Immune responses to FVIII sequence variants encoded by ns-SNPs do not contribute appreciably to inhibitor development in African Americans. African American HA subjects with an intron-22 inversion had a 2- to 3-times-higher inhibitor incidence than whites with the same mutation.
Increasing the inspiratory time and I:E ratio during mechanical ventilation aggravates ventilator-induced lung injury in mice
Authors: Müller-Redetzky Holger C , Felten Matthias , Hellwig Katharina , Wienhold Sandra-Maria , Naujoks Jan , Opitz Bastian , Kershaw Olivia , Gruber Achim D , Suttorp Norbert , Witzenrath Martin
Published: January 2015

Introduction

Lung-protective ventilation reduced acute respiratory distress syndrome (ARDS) mortality. To minimize ventilator-induced lung injury (VILI), tidal volume is limited, high plateau pressures are avoided, and positive end-expiratory pressure (PEEP) is applied. However, the impact of specific ventilatory patterns on VILI is not well defined. Increasing inspiratory time and thereby the inspiratory/expiratory ratio (I:E ratio) may improve oxygenation, but may also be harmful as the absolute stress and strain over time increase. We thus hypothesized that increasing inspiratory time and I:E ratio aggravates VILI.

Methods

VILI was induced in mice by high tidal-volume ventilation (HVT 34 ml/kg). Low tidal-volume ventilation (LVT 9 ml/kg) was used in control groups. PEEP was set to 2 cm H2O, FiO2 was 0.5 in all groups. HVT and LVT mice were ventilated with either I:E of 1:2 (LVT 1:2, HVT 1:2) or 1:1 (LVT 1:1, HVT 1:1) for 4 hours or until an alternative end point, defined as mean arterial blood pressure below 40 mm Hg. Dynamic hyperinflation due to the increased I:E ratio was excluded in a separate group of animals. Survival, lung compliance, oxygenation, pulmonary permeability, markers of pulmonary and systemic inflammation (leukocyte differentiation in lung and blood, analyses of pulmonary interleukin-6, interleukin-1β, keratinocyte-derived chemokine, monocyte chemoattractant protein-1), and histopathologic pulmonary changes were analyzed.

Results

LVT 1:2 or LVT 1:1 did not result in VILI, and all individuals survived the ventilation period. HVT 1:2 decreased lung compliance, increased pulmonary neutrophils and cytokine expression, and evoked marked histologic signs of lung injury. All animals survived. HVT 1:1 caused further significant worsening of oxygenation, compliance and increased pulmonary proinflammatory cytokine expression, and pulmonary and blood neutrophils. In the HVT 1:1 group, significant mortality during mechanical ventilation was observed.

Conclusion

According to the “baby lung” concept, mechanical ventilation-associated stress and strain in overinflated regions of ARDS lungs was simulated by using high tidal-volume ventilation. Increase of inspiratory time and I:E ratio significantly aggravated VILI in mice, suggesting an impact of a “stress/strain × time product” for the pathogenesis of VILI. Thus increasing the inspiratory time and I:E ratio should be critically considered.
Netrins and Frazzled/DCC promote the migration and mesenchymal to epithelial transition of Drosophila midgut cells
Authors: Pert Melissa , Gan Miao , Saint Robert , Murray Michael J.
Published: January 2015

Mesenchymal-epithelial transitions (METs) are important in both development and the growth of secondary tumours. Although the molecular basis for epithelial polarity is well studied, less is known about the cues that induce MET. Here we show that Netrins, well known as chemotropic guidance factors, provide a basal polarising cue during the Drosophila midgut MET. Both netrinA and netrinB are expressed in the visceral mesoderm, the substrate upon which midgut cells migrate, while their receptor frazzled (fra) is expressed in midgut cells. Netrins are required to polarise Fra to the basal surface, and Netrins and Fra undergo mutually-dependent endocytosis, with Fra subsequently trafficking to late endosomes. Mutations to fra and netrins affect both migration and MET but to different degrees. Loss of fra strongly delays migration, midgut cells fail to extend protrusions, and apico-basal polarisation of proteins and epithelium formation is inhibited. In netrin mutants, the migration phenotype is weaker and cells still extend protrusions. However, apico-basal polarisation of proteins, including Fra, and FActin is greatly disrupted and a monolayer fails to form. Delocalised accumulations of FActin are prevalent in netrin mutants but not fra mutants suggesting delocalised Fra may disrupt the MET. βPS localisation is also affected in netrin mutants in that a basal gradient is reduced while localisation to the midgut/VM interface is increased. Since a similar effect is seen when endocytosis is inhibited, Netrin and Fra may regulate Integrin turnover. The results suggest Netrin-dependent basal polarisation of Fra is critical for the formation of an epithelium.
mir-34b/c and mir-449a/b/c are required for spermatogenesis, but not for the first cleavage division in mice
Authors: Yuan Shuiqiao , Tang Chong , Zhang Ying , Wu Jingwen , Bao Jianqiang , Zheng Huili , Xu Chen , Yan Wei
Published: January 2015

Mammalian sperm are carriers of not only the paternal genome, but also the paternal epigenome in the forms of DNA methylation, retained histones and noncoding RNAs. Although paternal DNA methylation and histone retention sites have been correlated with protein-coding genes that are critical for preimplantation embryonic development, physiological evidence of an essential role of these epigenetic marks in fertilization and early development remains lacking. Two miRNA clusters consisting of five miRNAs (miR-34b/c and miR-449a/b/c) are present in sperm, but absent in oocytes, and miR-34c has been reported to be essential for the first cleavage division in vitro. Here, we show that both miR-34b/c- and miR-449-null male mice displayed normal fertility, and that intracytoplasmic injection of either miR-34b/c- or miR-449-null sperm led to normal fertilization, normal preimplantation development and normal birth rate. However, miR-34b/c and miR-449 double knockout (miR-dKO) males were infertile due to severe spermatogenic disruptions and oligo-astheno-teratozoospermia. Injection of miR-dKO sperm into wild-type oocytes led to a block at the two-pronucleus to zygote transition, whereas normal preimplantation development and healthy pups were obtained through injection of miR-dKO round spermatids. Our data demonstrate that miR-34b/c and miR-449a/b/c are essential for normal spermatogenesis and male fertility, but their presence in sperm is dispensable for fertilization and preimplantation development.
Snail2/Slug cooperates with Polycomb repressive complex 2 (PRC2) to regulate neural crest development
Authors: Tien Chih-Liang , Jones Amanda , Wang Hengbin , Gerigk Magda , Nozell Susan , Chang Chenbei
Published: January 2015

Neural crest cells arise from the border of the neural plate and epidermal ectoderm, migrate extensively and differentiate into diverse cell types during vertebrate embryogenesis. Although much has been learnt about growth factor signals and gene regulatory networks that regulate neural crest development, limited information is available on how epigenetic mechanisms control this process. In this study, we show that Polycomb repressive complex 2 (PRC2) cooperates with the transcription factor Snail2/Slug to modulate neural crest development in Xenopus. The PRC2 core components Eed, Ezh2 and Suz12 are expressed in the neural crest cells and are required for neural crest marker expression. Knockdown of Ezh2, the catalytic subunit of PRC2 for histone H3K27 methylation, results in defects in neural crest specification, migration and craniofacial cartilage formation. EZH2 interacts directly with Snail2, and Snail2 fails to expand the neural crest domains in the absence of Ezh2. Chromatin immunoprecipitation analysis shows that Snail2 regulates EZH2 occupancy and histone H3K27 trimethylation levels at the promoter region of the Snail2 target E-cadherin. Our results indicate that Snail2 cooperates with EZH2 and PRC2 to control expression of the genes important for neural crest specification and migration during neural crest development.
Plant embryogenesis requires AUX/LAX-mediated auxin influx
Authors: Robert Hélène S. , Grunewald Wim , Sauer Michael , Cannoot Bernard , Soriano Mercedes , Swarup Ranjan , Weijers Dolf , Bennett Malcolm , Boutilier Kim , Friml Jiří
Published: January 2015

The plant hormone auxin and its directional transport are known to play a crucial role in defining the embryonic axis and subsequent development of the body plan. Although the role of PIN auxin efflux transporters has been clearly assigned during embryonic shoot and root specification, the role of the auxin influx carriers AUX1 and LIKE-AUX1 (LAX) proteins is not well established. Here, we used chemical and genetic tools on Brassica napus microspore-derived embryos and Arabidopsis thaliana zygotic embryos, and demonstrate that AUX1, LAX1 and LAX2 are required for both shoot and root pole formation, in concert with PIN efflux carriers. Furthermore, we uncovered a positive-feedback loop between MONOPTEROS (ARF5)-dependent auxin signalling and auxin transport. This MONOPTEROS-dependent transcriptional regulation of auxin influx (AUX1, LAX1 and LAX2) and auxin efflux (PIN1 and PIN4) carriers by MONOPTEROS helps to maintain proper auxin transport to the root tip. These results indicate that auxin-dependent cell specification during embryo development requires balanced auxin transport involving both influx and efflux mechanisms, and that this transport is maintained by a positive transcriptional feedback on auxin signalling.
Vascular patterning regulates interdigital cell death by a ROS-mediated mechanism
Authors: Eshkar-Oren Idit , Krief Sharon , Ferrara Napoleone , Elliott Alison M. , Zelzer Elazar
Published: January 2015

Blood vessels serve as key regulators of organogenesis by providing oxygen, nutrients and molecular signals. During limb development, programmed cell death (PCD) contributes to separation of the digits. Interestingly, prior to the onset of PCD, the autopod vasculature undergoes extensive patterning that results in high interdigital vascularity. Here, we show that in mice, the limb vasculature positively regulates interdigital PCD. In vivo, reduction in interdigital vessel number inhibited PCD, resulting in syndactyly, whereas an increment in vessel number and distribution resulted in elevation and expansion of PCD. Production of reactive oxygen species (ROS), toxic compounds that have been implicated in PCD, also depended on interdigital vascular patterning. Finally, ex vivo incubation of limbs in gradually decreasing oxygen levels led to a correlated reduction in both ROS production and interdigital PCD. The results support a role for oxygen in these processes and provide a mechanistic explanation for the counterintuitive positive role of the vasculature in PCD. In conclusion, we suggest a new role for vascular patterning during limb development in regulating interdigital PCD by ROS production. More broadly, we propose a double safety mechanism that restricts PCD to interdigital areas, as the genetic program of PCD provides the first layer and vascular patterning serves as the second.
Sharing the cell's bounty – organelle inheritance in yeast
Authors: Knoblach Barbara , Rachubinski Richard A.
Published: January 2015

Eukaryotic cells replicate and partition their organelles between the mother cell and the daughter cell at cytokinesis. Polarized cells, notably the budding yeast Saccharomyces cerevisiae, are well suited for the study of organelle inheritance, as they facilitate an experimental dissection of organelle transport and retention processes. Much progress has been made in defining the molecular players involved in organelle partitioning in yeast. Each organelle uses a distinct set of factors – motor, anchor and adaptor proteins – that ensures its inheritance by future generations of cells. We propose that all organelles, regardless of origin or copy number, are partitioned by the same fundamental mechanism involving division and segregation. Thus, the mother cell keeps, and the daughter cell receives, their fair and equitable share of organelles. This mechanism of partitioning moreover facilitates the segregation of organelle fragments that are not functionally equivalent. In this Commentary, we describe how this principle of organelle population control affects peroxisomes and other organelles, and outline its implications for yeast life span and rejuvenation.
Hypoxia increases extracellular fibronectin abundance but not assembly during epithelial cell transdifferentiation
Authors: Rana Manish Kumar , Srivastava Jyoti , Yang Michael , Chen Christopher S. , Barber Diane L.
Published: January 2015

Increased production and assembly of extracellular matrix proteins during transdifferentiation of epithelial cells to a mesenchymal phenotype contributes to diseases such as renal and pulmonary fibrosis. TGF-β and hypoxia, two cues that initiate injury-induced fibrosis, caused a mesenchymal phenotype of human kidney cells, including increased fibronectin expression and secretion. However, assembled extracellular fibronectin fibrils with hypoxia were mostly absent compared with abundant fibrils with TGF-β. Fibrillogenesis requires cell-generated force and tension. TGF-β but not hypoxia increased cell contractility, determined by phosphorylation of myosin light chain and quantifying force and tension generated by cells plated on engineered elastomeric microposts. Additionally, TGF-β but not hypoxia increased activation of integrins; however, experimentally activating integrins markedly increased phosphorylated myosin light chain and fibronectin fibril assembly with hypoxia. Our findings show that deficient integrin activation and cell contractility as a mechanism for lack of fibrillogenesis with hypoxia and they challenge current views on oxygen deprivation being sufficient for fibrosis.
The Wnt receptor Frizzled-4 modulates ADAM13 metalloprotease activity
Authors: Abbruzzese Genevieve , Gorny Anne-Kathrin , Kaufmann Lilian T. , Cousin Hélène , Kleino Iivari , Steinbeisser Herbert , Alfandari Dominique
Published: January 2015

Cranial neural crest cells (CNC) are a transient population of “stem cells” that originate at the border of the neural plate and the epidermis and migrate ventrally to contribute to most of the facial structures including bones, cartilage, muscles and ganglia. ADAM13 is a cell surface metalloprotease that is essential for CNC migration. Here we show that a Wnt receptor, Fz4, binds to the cysteine rich domain of ADAM13 and negatively regulate its proteolytic activity in vivo. Gain of Fz4 function inhibit CNC migration and can be rescued by gain of ADAM13 function. Loss of Fz4 function also inhibits CNC migration and induces a reduction of mature ADAM13 together with an increase in the ADAM13 cytoplasmic fragment that is known to translocate in the nucleus to regulate gene expression. We propose that Fz4 associate with ADAM13 during transport to the plasma membrane to regulate its proteolytic activity.
Variation in early-life telomere dynamics in a long-lived bird: links to environmental conditions and survival
Authors: Watson Hannah , Bolton Mark , Monaghan Pat
Published: January 2015

Conditions experienced during early life can have profound consequences for both short- and long-term fitness. Variation in the natal environment has been shown to influence survival and reproductive performance of entire cohorts in wild vertebrate populations. Telomere dynamics potentially provide a link between the early environment and long-term fitness outcomes, yet we know little about how the environment can influence telomere dynamics in early life. We found that environmental conditions during growth have an important influence on early-life telomere length (TL) and attrition in nestlings of a long-lived bird, the European storm petrel Hydrobates pelagicus. Nestlings reared under unfavourable environmental conditions experienced significantly greater telomere loss during postnatal development compared with nestlings reared under more favourable natal conditions, which displayed a negligible change in TL. There was, however, no significant difference in pre-fledging TL between cohorts. The results suggest that early-life telomere dynamics could contribute to the marked differences in life-history traits that can arise among cohorts reared under different environmental conditions. Early-life TL was also found to be a significant predictor of survival during the nestling phase, providing further evidence for a link between variation in TL and individual fitness. To what extent the relationship between early-life TL and mortality during the nestling phase is a consequence of genetic, parental and environmental factors is currently unknown, but it is an interesting area for future research. Accelerated telomere attrition under unfavourable conditions, as observed in this study, might play a role in mediating the effects of the early-life environment on later-life performance.
The role of egg-nest contrast in the rejection of brood parasitic eggs
Authors: Aidala Zachary , Croston Rebecca , Schwartz Jessica , Tong Lainga , Hauber Mark E.
Published: January 2015

Hosts of avian brood parasites can avoid the reproductive costs of raising genetically unrelated offspring by rejecting parasitic eggs. The perceptual cues and controls mediating parasitic egg discrimination and ejection are well studied: hosts are thought to use differences in egg color, brightness, maculation, size, and shape to discriminate between own and foreign eggs. Most models of brood parasitism implicitly assume that the primary criteria to which hosts attend when discriminating eggs are differences between the eggs themselves. However, this assumption is confounded by the degree to which chromatic and achromatic characteristics of the nest lining co-vary with egg coloration, in that egg-nest contrast per se might be the recognition cue driving parasitic egg detection. Here we systematically tested whether and how egg-nest contrast itself contributes to foreign egg discrimination. In an artificial parasitism experiment, we independently manipulated egg color and nest lining color of the egg-ejector American robin (Turdus migratorius), a host of the obligate brood parasitic brown-headed cowbird (Molothrus ater). We hypothesized that the degree of contrast between foreign eggs and the nest background would affect host egg rejection behavior. We predicted that experimentally decreasing egg-nest chromatic and achromatic contrast (i.e. rendering parasitic eggs more cryptic against the nest lining) would decrease rejection rates, while increasing egg-nest contrast would increase rejection rates. In contrast to our predictions, egg-nest contrast was not a significant predictor of egg ejection patterns. Instead, egg color significantly predicted responses to parasitism. We conclude that egg-egg differences are the primary drivers of egg rejection in this system. Future studies should test for the effects of egg-nest contrast per se in predicting parasitic egg recognition in other host-parasite systems, including those hosts building enclosed nests and parasites laying cryptic eggs, as an alternative to hypothesized effects of egg-egg contrasts.
Common measures of immune function vary with time of day and sampling protocol in five passerine species
Authors: Zylberberg Maxine
Published: January 2015

Ecological immunology is a rapidly growing field of study that focuses on understanding variation in immune systems across species and how this relates to species ecology and evolution. Newly developed field methods aimed at studying variation in immune function in a field setting have yielded many insights. Nonetheless, there continues to be much debate regarding the interpretation of field measures of immune function. There is substantial evidence to suggest that handling stress could introduce variation into measures of immune function, yet no study has examined the impacts of incremental changes in handling times under 30 min on immune measures. Nor has any study examined variation in immune function with time of day, though other physiological measures, including glucocorticoids known to impact immune function, vary with time of day. Here, I used observational field data to test the hypothesis that innate immune function varies with handling stress. Furthermore, I tested the hypothesis that innate immune function changes over the course of the day. I show that measures of innate immune function vary with (1) handling stress over short time periods typical of sample collection in the field, and (2) the time of day that an individual is sampled. I discuss these findings from an ecological perspective and suggest that the observed variation is not random, but is likely to have important adaptive functions. I end with a summary of the practical implications of these findings for field studies of ecological immunology.
Regulatory mechanisms of metabolic flexibility in the dark-eyed junco (Junco hyemalis)
Authors: Stager Maria , Swanson David L. , Cheviron Zachary A.
Published: January 2015

Small temperate birds reversibly modify their aerobic performance to maintain thermoregulatory homeostasis under seasonally changing environmental conditions and these physiological adjustments may be attributable to changes in the expression of genes in the underlying regulatory networks. Here, we report the results of an experimental procedure designed to gain insight into the fundamental mechanisms of metabolic flexibility in the dark-eyed junco (Junco hyemalis). We combined genomic transcriptional profiles with measures of metabolic enzyme activities and whole-animal thermogenic performance from juncos exposed to four 6-week acclimation treatments that varied in temperature (cold, 3°C; warm, 24°C) and photoperiod (short day, 8 h light:16 h dark; long day, 16 h light:8 h dark). Cold-acclimated birds increased thermogenic capacity compared with warm-acclimated birds, and this enhanced performance was associated with upregulation of genes involved in muscle hypertrophy, angiogenesis, and lipid transport and oxidation, as well as with catabolic enzyme activities. These physiological changes occurred over ecologically relevant timescales, suggesting that birds make regulatory adjustments to interacting, hierarchical pathways in order to seasonally enhance thermogenic capacity.
Evolutionary adaptations for the temporal processing of natural sounds by the anuran peripheral auditory system
Authors: Schrode Katrina M. , Bee Mark A.
Published: January 2015

Sensory systems function most efficiently when processing natural stimuli, such as vocalizations, and it is thought that this reflects evolutionary adaptation. Among the best-described examples of evolutionary adaptation in the auditory system are the frequent matches between spectral tuning in both the peripheral and central auditory systems of anurans (frogs and toads) and the frequency spectra of conspecific calls. Tuning to the temporal properties of conspecific calls is less well established, and in anurans has so far been documented only in the central auditory system. Using auditory evoked potentials, we asked whether there are species-specific or sex-specific adaptations of the auditory systems of gray treefrogs (Hyla chrysoscelis) and green treefrogs (H. cinerea) to the temporal modulations present in conspecific calls. Modulation rate transfer functions (MRTFs) constructed from auditory stead-state responses (ASSRs) revealed that each species was more sensitive than the other to the modulation rates typical of conspecific advertisement calls. In addition, auditory brainstem responses (ABRs) to paired-clicks indicated relatively better temporal resolution in green treefrogs, which could represent an adaptation to the faster modulation rates present in this species' calls. MRTFs and recovery of ABRs to paired-clicks were generally similar between the sexes, and we found no evidence that males were more sensitive than females to the temporal modulation patterns characteristic of the aggressive calls used in male-male competition. Together, our results suggest that efficient processing of the temporal properties of behaviorally relevant sounds begins at potentially very early stages of the anuran auditory system that include the periphery.
How effective are acoustic signals in territorial defence in the Lusitanian toadfish?
Authors: Conti Carlotta , Fonseca Paulo J. , Picciulin Marta , Amorim Maria Clara P.
Published: January 2015

The function of fish sounds in territorial defence, in particular its influence on the intruder's behaviour during territorial invasions, is poorly known. Breeding Lusitanian toadfish males (Halobatrachus didactylus) use sounds (boatwhistles) to defend nests from intruders. Results from a previous study suggest that boatwhistles function as a 'keep-out signal' during territorial defence. To test this hypothesis we performed territorial intrusion experiments with muted Lusitanian toadfish. Subject males were assigned to three groups: muted, sham and unmanipulated. Males were muted by making a cut and deflating the swimbladder (the sound producing apparatus) under anaesthesia. Sham males suffered the same surgical procedure except the swimbladder cut and deflation. Toadfish nest-holder males reacted to intruders mainly by emitting sounds (sham and unmanipulated) and less frequently with escalated fights. When the nest-holder produced a boatwhistle, the intruder fled more frequently than expected by chance alone. Muted males experienced a higher number of intrusions than the remaining groups probably due to their inability to vocalise. Together, our results show that fish acoustic signals are effective deterrents in nest/territorial intrusions, similar to bird song.