Balancing key stakeholder priorities and ethical principles to design a trial comparing intervention or expectant management for early-onset selective fetal growth restriction in monochorionic twin pregnancy: FERN qualitative study.

OBJECTIVES: As part of the FERN feasibility study, this qualitative research aimed to explore parents' and clinicians' views on the acceptability, feasibility and design of a randomised controlled trial (RCT) of active intervention versus expectant management in monochorionic (MC) diamniotic twin pregnancies with early-onset (prior to 24 weeks) selective fetal growth restriction (sFGR). Interventions could include laser treatment or selective termination which could lead to the death or serious disability of one or both twins. DESIGN: Qualitative semi-structured interviews with parents and clinicians. Data were analysed using reflexive thematic analysis and considered against the Principles of Biomedical Ethics. PARTICIPANTS AND SETTING: We interviewed 19 UK parents experiencing (six mothers, two partners) or had recently experienced (eight mothers, three partners) early-onset sFGR in MC twin pregnancy and 14 specialist clinicians from the UK and Europe. RESULTS: Participants viewed the proposed RCT as 'ethically murky' because they believed that the management of sFGR in MC twin pregnancy should be individualised according to the type and severity of sFGR. Clinicians prioritised the gestational age, size, decrease in growth velocity, access to the placental vessels and acceptability of intervention for parents. Discussions and decision-making about selective termination appeared to cause long-term harm (maleficence). The most important outcome for parents and clinicians was 'live birth'. For clinicians, this was the live birth of at least one twin. For parents, this meant the live birth of both twins, even if this meant that their babies had neurodevelopmental impairment or disabilities. CONCLUSIONS: All three pregnancy management approaches for sFGR in MC twin pregnancy carry risks and benefits, and the ultimate goal for parents is to receive individualised care to achieve the best possible outcome for both twins. An RCT was not acceptable to parents or clinicians or seen as ethically appropriate. Alternative study designs should be considered to answer this important research question.

Diagnosis and management of selective fetal growth restriction in monochorionic twin pregnancies: A cross-sectional international survey.

OBJECTIVE: To identify current practices in the management of selective fetal growth restriction (sFGR) in monochorionic diamniotic (MCDA) twin pregnancies. DESIGN: Cross-sectional survey. SETTING: International. POPULATION: Clinicians involved in the management of MCDA twin pregnancies with sFGR. METHODS: A structured, self-administered survey. MAIN OUTCOME MEASURES: Clinical practices and attitudes to diagnostic criteria and management strategies. RESULTS: Overall, 62.8% (113/180) of clinicians completed the survey; of which, 66.4% (75/113) of the respondents reported that they would use an estimated fetal weight (EFW) of <10th centile for the smaller twin and an inter-twin EFW discordance of >25% for the diagnosis of sFGR. For early-onset type I sFGR, 79.8% (75/94) of respondents expressed that expectant management would be their routine practice. On the other hand, for early-onset type II and type III sFGR, 19.3% (17/88) and 35.7% (30/84) of respondents would manage these pregnancies expectantly, whereas 71.6% (63/88) and 57.1% (48/84) would refer these pregnancies to a fetal intervention centre or would offer fetal intervention for type II and type III cases, respectively. Moreover, 39.0% (16/41) of the respondents would consider fetoscopic laser surgery (FLS) for early-onset type I sFGR, whereas 41.5% (17/41) would offer either FLS or selective feticide, and 12.2% (5/41) would exclusively offer selective feticide. For early-onset type II and type III sFGR cases, 25.9% (21/81) and 31.4% (22/70) would exclusively offer FLS, respectively, whereas 33.3% (27/81) and 32.9% (23/70) would exclusively offer selective feticide. CONCLUSIONS: There is significant variation in clinician practices and attitudes towards the management of early-onset sFGR in MCDA twin pregnancies, especially for type II and type III cases, highlighting the need for high-level evidence to guide management.

Mixed-methods feasibility study to inform a randomised controlled trial of proton pump inhibitors to reduce strictures following neonatal surgery for oesophageal atresia.

OBJECTIVES: This mixed-methods feasibility study aimed to explore parents' and medical practitioners' views on the acceptability and design of a clinical trial to determine whether routine prophylactic proton pump inhibitors (PPI) reduce the incidence of anastomotic stricture in infants with oesophageal atresia (OA). DESIGN: Semi-structured interviews with UK parents of an infant with OA and an online survey, telephone interviews and focus groups with clinicians. Data were analysed using reflexive thematic analysis and descriptive statistics. PARTICIPANTS AND SETTING: We interviewed 18 parents of infants with OA. Fifty-one clinicians (49 surgeons, 2 neonatologists) from 20/25 (80%) units involved in OA repair completed an online survey and 10 took part in 1 of 2 focus groups. Interviews were conducted with two clinicians whose survey responses indicated they had concerns about the trial. OUTCOME MEASURES: Parents and clinicians ranked the same top four outcomes ('Severity of anastomotic stricture', 'Incidence of anastomotic stricture', 'Need for treatment of reflux' and 'Presence of symptoms of reflux') as important to measure for the proposed trial. RESULTS: All parents and most clinicians found the use, dose and duration of omeprazole as the intervention medication, and the placebo control, as acceptable. Parents stated they would hypothetically consent to their child's participation in the trial. Concerns of a few parents and clinicians about infants suffering with symptomatic reflux, and the impact of this for study retention, appeared to be alleviated through the symptomatic reflux treatment pathway. Hesitant clinician views appeared to change through discussion of parental support for the study and by highlighting existing research that questions current practice of PPI treatment. CONCLUSIONS: Our findings indicate that parents and most clinicians view the proposed Treating Oesophageal Atresia with prophylactic proton pump inhibitors to prevent STricture (TOAST) trial to be feasible and acceptable so long as infants can be given PPI if clinicians deem it clinically necessary. This insight into parent and clinician views and concerns will inform pilot phase trial monitoring, staff training and the development of the trial protocol.

'I feel like my house was taken away from me': Parents' experiences of having home adaptations for their medically complex, technology-dependent child.

Technology-dependent children are a sub-population of seriously ill children with life-limiting conditions who are being cared for at home by their families. Although home-based care has been the model of care for these children since the late 1980s, there is a paucity of literature about parents' experiences of having home adaptations made to enable their home to be a place of care for their child. Using the findings from auto-driven photo-elicitation interviews conducted between August 2017 and June 2018 with 12 parents (10 mothers and 2 fathers) who have a technology-dependent child (aged 5-25 years) living in England, Scotland and Wales and David Seamon's five concepts of at-homeness (appropriation, at-easeness, regeneration, rootedness and warmth) as a conceptual framework, this paper addresses how parents' experienced home adaptations. Thematic analysis generated a meta-theme of 'Home needs to be a home for all family members' and the three key themes: (1) 'You just get told' and 'you're not involved'; (2) It's just the 'cheapest', 'quickest', 'short-term' approach; (3) Having 'control' and 'thinking things through.' The need to involve parents in decision-making about adaptations that are made to their home (family-informed design) is clear, not only from a cost-saving perspective for the state, but for creating an aesthetic and functional home that optimises health, well-being and feelings of at-homeness for the entire family.

'It doesn't feel like our house anymore': The impact of medical technology upon life at home for families with a medically complex, technology-dependent child.

The study aimed to identify how medical technology impacts upon the home and life at home. Inductive auto-driven photo-elicitation or semi-structured interviews were conducted with technology-dependent children/young people (n = 2) and their family members (n = 15) from 10 families. Thematic analysis generated three themes: Altered physicality and look of the home; Altered sounds in the home; and 'It's worth it! Technology enables us to stay as a family'. Fundamentally, the detrimental impacts of living with medical technology were perceived as worth it as these enabled their child to be at home. Home was not home, and families were incomplete without their child at home.

GSK3732394: a Multi-specific Inhibitor of HIV Entry.

Long-acting antiretrovirals could provide a useful alternative to daily oral therapy for HIV-1-infected individuals. Building on a bi-specific molecule with adnectins targeting CD4 and gp41, a potential long-acting biologic, GSK3732394, was developed with three independent and synergistic modes of HIV entry inhibition that potentially could be self-administered as a long-acting subcutaneous injection. Starting with the bi-specific inhibitor, an α-helical peptide inhibitor was optimized as a linked molecule to the anti-gp41 adnectin, with each separate inhibitor exhibiting at least single-digit nanomolar (or lower) potency and a broad spectrum. Combination of the two adnectins and peptide activities into a single molecule was shown to have synergistic advantages in potency, the resistance barrier, and the ability to inhibit HIV-1 infections at low levels of CD4 receptor occupancy, showing that GSK3732394 can work in trans on a CD4+ T cell. Addition of a human serum albumin molecule prolongs the half-life in a human CD4 transgenic mouse, suggesting that it may have potential as a long-acting agent. GSK3732394 was shown to be highly effective in a humanized mouse model of infection. GSK3732394 is currently in clinical trials.IMPORTANCE There continue to be significant unmet medical needs for patients with HIV-1 infection. One way to improve adherence and decrease the likelihood of drug-drug interactions in HIV-1-infected patients is through the development of long-acting biologic inhibitors. Building on a bi-specific inhibitor approach targeting CD4 and gp41, a tri-specific molecule was generated with three distinct antiviral activities. The linkage of these three biologic inhibitors creates synergy that offers a series of advantages to the molecule. The addition of human serum albumin to the tri-specific inhibitor could allow it to function as a long-acting self-administered treatment for patients with HIV infection. This molecule is currently in early clinical trials.

A qualitative study of health care professionals' views and experiences of paediatric advance care planning.

BACKGROUND: Good end-of-life care planning is vital to ensure optimal care is provided for patients and their families. Two key factors are open and honest advance care planning conversations between the patient (where possible), family, and health care professionals, focusing on exploring what their future wishes are; and the development of an advance care plan document. However, in paediatric and neonatal settings, there has been little research to demonstrate how advance care planning conversations take place. This study explored health care professionals' views and experiences of paediatric advance care planning in hospitals, community settings and hospices. METHODS: A qualitative methodology was employed using purposive sampling of health care professionals involved in the end-of-life care for children aged 0-18 years known to the hospital palliative care team, and had died at least three months before, but less than 18 months prior to the study. Ethics committee approval was obtained for the study. Located in the North of England, the study involved three hospitals, a children's hospice, and community services. Data were collected using semi-structured, digitally recorded, telephone interviews. All interviews were transcribed verbatim and subjected to thematic analysis. RESULTS: Twenty-one health care professionals participated, including generalist paediatric staff as well as specialist palliative care staff. Two themes were generated from the study: The timing of planning conversations, including waiting for the relationship with the family to form; the introduction of parallel planning; avoiding a crisis situation. Secondly, supporting effective conversations around advance care planning, including where to have the conversation; introducing the conversation; and how to approach the topic encompassing the value of advance care planning and documentation for families. CONCLUSION: The timing of when to start the advance care planning conversations remains an issue for health care professionals. The value of doing it in stages and considering the environment where the conversations are held was noted. Timely planning was seen as vital to avoid difficult conversations at a crisis point and for co-ordination of care. Good advance care planning is to provide the best person-centred care for the child and experience for the family.

Meeting the needs of young adults with life-limiting conditions: A UK survey of current provision and future challenges for hospices.

AIM: The aim of this study was to seek views of UK children's and adult hospices on the availability and challenges of providing services for young adults with life-limiting conditions. BACKGROUND: Internationally, there are a growing number of young adults with life-limiting conditions and/or complex needs which are degenerative, progressive and diverse and involve complex life-long symptom, medication management as well as palliative care. There are 55,721 young adults, aged 18-40 in England, which continues to increase. The hospice sector is experiencing demands to extend services for this population despite concerns about the appropriateness of adult hospices and their nursing staff to provide care for the complex and unfamiliar conditions of this patient group. Evidence is needed of hospices' views and the main challenges faced providing services for young adults. DESIGN: Descriptive cross-sectional survey. METHODS: xChildren and adult hospices completed an online survey exploring service provision and their views of respite care for young adults with life-limiting conditions from 18 years old and onward. Data were collected between October 2015 - February 2016. FINDINGS: Respondents (N = 76 hospices) reported that children's hospices predominantly provided short breaks and end-of-life care; adult hospices provided mainly symptom management, end-of-life care and day services. Main challenges were lack of existing adult respite services; lack of funding and capacity; lack of a skilled workforce in adult hospices; and the need for better integrated service provision. CONCLUSION: Examples of good collaborative working were reported. With an increasing population of young adults and pressure on families, it is vital that services work together to find sustainable solutions to the challenges.

Supporting older people with cancer and life-limiting conditions dying at home: a qualitative study of patient and family caregiver experiences of Hospice at Home care.

AIM: To explore patients' and family caregivers' experiences and perceptions of Hospice at Home care. BACKGROUND: The public indicate a preference to be cared for and to die at home. This has inherent challenges, with a key factor being the family caregiver. Supporting end-of-life care at home has resulted in the expansion of Hospice at Home services. A wide configuration of services exists with a lack of robust evidence as to what is valued by recipients, particularly those who are older people. DESIGN: A prospective descriptive qualitative study. METHODS: Recruitment was purposive. Eligible participants were in receipt of Hospice at Home service on at least three occasions and were deemed to have a life expectancy measured in weeks rather than days. Digitally recorded semistructured interviews with 41 participants (16 patients and 25 family caregivers) were undertaken between October 2014 - July 2015. Data were analysed and organized thematically. RESULTS: Several subthemes: 'Talking about'; 'Knowing and Doing'; 'Caring for the Caregivers'; and 'Promoting Choice' contributed to the overall theme of Embracing Holism. A positive impact on emotional, psychological, social and physical well-being was apparent. CONCLUSIONS: This study has provided additional insights as to the value of Hospice at Home care where Hospice Nurses are helping to bring Hospice care into the home. This is helping to support older people who are dying and their caregivers, to live as well as possible and facilitate their wish to be cared for and die in their own home.

Short break and emergency respite care: what options for young people with life-limiting conditions?

BACKGROUND: Service providers face difficult decisions about how best to develop services for the increasing numbers of young people with life-limiting conditions who require palliative care. OBJECTIVE: To explore alternative short break and emergency respite care options to children's hospice care. METHODS: A two-phase evaluation with young people, families and professionals. Phase 1: qualitative semi-structured interviews and focus groups (n=53). Phase 2: mixed-method survey (n=82), qualitative findings only. RESULTS: There were few, or no, appropriate short break and emergency respite care alternatives when children's hospice care was not available that can meet the need of young people with life-limiting conditions, creating anxiety for children's hospice users and those leaving the service as a result of reaching transition age or through no longer meeting the children's hospice eligibility criteria. CONCLUSION: Access to appropriate short break and emergency respite care is required to prevent lifelong negative consequences for young people with life-limiting conditions, their family and society. Research is undoubtedly required to explore the impact and outcomes of children's hospice discharge for young people and their family. Particular attention should be paid to the lack of services for an increasing population making the transition from children's hospices.

Pharmacologic profile of the Adnectin BMS-962476, a small protein biologic alternative to PCSK9 antibodies for low-density lipoprotein lowering.

Proprotein convertase subtilisin kexin-9 (PCSK9) is an important pharmacological target for decreasing low-density lipoprotein (LDL) in cardiovascular disease, although seemingly inaccessible to small molecule approaches. Compared with therapeutic IgG antibodies currently in development, targeting circulating PCSK9 with smaller molecular scaffolds could offer different profiles and reduced dose burdens. This inspired genesis of PCSK9-binding Adnectins, a protein family derived from human fibronectin-10th-type III-domain and engineered for high-affinity target binding. BMS-962476, an ∼11-kDa polypeptide conjugated to polyethylene glycol to enhance pharmacokinetics, binds with subnanomolar affinity to human. The X-ray cocrystal structure of PCSK9 with a progenitor Adnectin shows ∼910 Å(2) of PCSK9 surface covered next to the LDL receptor binding site, largely by residues of a single loop of the Adnectin. In hypercholesterolemic, overexpressing human PCSK9 transgenic mice, BMS-962476 rapidly lowered cholesterol and free PCSK9 levels. In genomic transgenic mice, BMS-962476 potently reduced free human PCSK9 (ED50 ∼0.01 mg/kg) followed by ∼2-fold increases in total PCSK9 before return to baseline. Treatment of cynomolgus monkeys with BMS-962476 rapidly suppressed free PCSK9 >99% and LDL-cholesterol ∼55% with subsequent 6-fold increase in total PCSK9, suggesting reduced clearance of circulating complex. Liver sterol response genes were consequently downregulated, following which LDL and total PCSK9 returned to baseline. These studies highlight the rapid dynamics of PCSK9 control over LDL and liver cholesterol metabolism and characterize BMS-962476 as a potent and efficacious PCSK9 inhibitor.

Investigation of variability in image acquisition and contouring during 3D ultrasound guidance for partial breast irradiation.

BACKGROUND: Three-dimensional ultrasound (3DUS) at simulation compared to 3DUS at treatment is an image guidance option for partial breast irradiation (PBI). This study assessed if user dependence in acquiring and contouring 3DUS (operator variability) contributed to variation in seroma shifts calculated for breast IGRT. METHODS: Eligible patients met breast criteria for current randomized PBI studies. 5 Operators participated in this study. For each patient, 3 operators were involved in scan acquisitions and 5 were involved in contouring. At CT simulation (CT1), a 3DUS (US1) was performed by a single radiation therapist (RT). 7 to 14 days after CT1 a second CT (CT2) and 3 sequential 3DUS scans (US2a,b,c) were acquired by each of 3 RTs. Seroma shifts, between US1 and US2 scans were calculated by comparing geometric centers of the seromas (centroids). Operator contouring variability was determined by comparing 5 RT's contours for a single image set. Scanning variability was assessed by comparing shifts between multiple scans acquired at the same time point (US1-US2a,b,c). Shifts in seromas contoured on CT (CT1-CT2) were compared to US data. RESULTS: From an initial 28 patients, 15 had CT visible seromas, met PBI dosimetric constraints, had complete US data, and were analyzed. Operator variability contributed more to the overall variability in seroma localization than the variability associated with multiple scan acquisitions (95% confidence mean uncertainty of 6.2 mm vs. 1.1 mm). The mean standard deviation in seroma shift was user dependent and ranged from 1.7 to 2.9 mm. Mean seroma shifts from simulation to treatment were comparable to CT. CONCLUSIONS: Variability in shifts due to different users acquiring and contouring 3DUS for PBI guidance were comparable to CT shifts. Substantial inter-observer effect needs to be considered during clinical implementation of 3DUS IGRT.

A low-dose ipsilateral lung restriction improves 3-d conformal planning for partial breast radiation therapy.

In trials of 3D conformal external beam partial breast radiotherapy (PBRT), the dosimetrist must balance the priorities of achieving high conformity to the target versus minimizing low-dose exposure to the normal structures. This study highlights the caveat that in the absence of a low-dose lung restriction, the use of relatively en-face fields may meet trial-defined requirements but expose the ipsilateral lung to unnecessary low-dose radiation. Adding a low-dose restriction that ≤ 20% of the ipsilateral lung should receive 10% of the prescribed dose resulted in successful plans in 88% of cases. This low-dose lung limit should be used in PBRT planning.

3D ultrasound can contribute to planning CT to define the target for partial breast radiotherapy.

PURPOSE: The role of three-dimensional breast ultrasound (3D US) in planning partial breast radiotherapy (PBRT) is unknown. This study evaluated the accuracy of coregistration of 3D US to planning computerized tomography (CT) images, the seroma contouring consistency of radiation oncologists using the two imaging modalities and the clinical situations in which US was associated with improved contouring consistency compared to CT. MATERIALS AND METHODS: Twenty consecutive women with early-stage breast cancer were enrolled prospectively after breast-conserving surgery. Subjects underwent 3D US at CT simulation for adjuvant RT. Three radiation oncologists independently contoured the seroma on separate CT and 3D US image sets. Seroma clarity, seroma volumes, and interobserver contouring consistency were compared between the imaging modalities. Associations between clinical characteristics and seroma clarity were examined using Pearson correlation statistics. RESULTS: 3D US and CT coregistration was accurate to within 2 mm or less in 19/20 (95%) cases. CT seroma clarity was reduced with dense breast parenchyma (p = 0.035), small seroma volume (p < 0.001), and small volume of excised breast tissue (p = 0.01). US seroma clarity was not affected by these factors (p = NS). US was associated with improved interobserver consistency compared with CT in 8/20 (40%) cases. Of these 8 cases, 7 had low CT seroma clarity scores and 4 had heterogeneously to extremely dense breast parenchyma. CONCLUSION: 3D US can be a useful adjunct to CT in planning PBRT. Radiation oncologists were able to use US images to contour the seroma target, with improved interobserver consistency compared with CT in cases with dense breast parenchyma and poor CT seroma clarity.

RGS5 expression is a quantitative measure of pericyte coverage of blood vessels.

Pericytes play a key role in the process of vascular maturation and stabilization however, the current methods for quantifying pericyte coverage of the neovasculature are laborious and subjective in nature. In this study, we have developed an objective, sensitive, and high-throughput method for quantifying pericyte coverage of angiogenic vessels by analyzing the expression of the pericyte-specific gene, the regulator of G-protein signaling 5 (RGS5). We determined that RGS5 expression was up-regulated during a defined developmental time period in which nascent vessel sprouts acquired a pericyte covering. Furthermore, RGS5 expression was dramatically reduced in vessels with poor pericyte coverage compared to normal angiogenic vasculature. Finally, we determined that the susceptibility of nascent vessels to regression by vascular endothelial growth factor (VEGF) inhibition was significantly reduced following RGS5 up-regulation, further implicating RGS5 in pericyte-endothelial cell interactions and the vascular maturation process. These studies establish the use of RGS5 gene expression as a quantitative and robust measure of pericyte coverage of neovasculature. This method provides a tool for vascular biologists studying pericyte-endothelial cell interactions and vascular maturation in both normal and pathological conditions, such as diabetic retinopathy and cancer.

Birc2 (cIap1) regulates endothelial cell integrity and blood vessel homeostasis.

Integrity of the blood vessel wall is essential for vascular homeostasis and organ function. A dynamic balance between endothelial cell survival and apoptosis contributes to this integrity during vascular development and pathological angiogenesis. The genetic and molecular mechanisms regulating these processes in vivo are still largely unknown. Here, we show that Birc2 (also known as cIap1) is essential for maintaining endothelial cell survival and blood vessel homeostasis during vascular development. Using a forward-genetic approach, we identified a zebrafish null mutant for birc2, which shows severe hemorrhage and vascular regression due to endothelial cell integrity defects and apoptosis. Using genetic and molecular approaches, we show that Birc2 positively regulates the formation of the TNF receptor complex I in endothelial cells, thereby promoting NF-kappaB activation and maintaining vessel integrity and stabilization. In the absence of Birc2, a caspase-8-dependent apoptotic program takes place that leads to vessel regression. Our findings identify Birc2 and TNF signaling components as critical regulators of vascular integrity and endothelial cell survival, thereby providing an additional target pathway for the control of angiogenesis and blood vessel homeostasis during embryogenesis, regeneration and tumorigenesis.

A transgene-assisted genetic screen identifies essential regulators of vascular development in vertebrate embryos.

Formation of a functional vasculature during mammalian development is essential for embryonic survival. In addition, imbalance in blood vessel growth contributes to the pathogenesis of numerous disorders. Most of our understanding of vascular development and blood vessel growth comes from investigating the Vegf signaling pathway as well as the recent observation that molecules involved in axon guidance also regulate vascular patterning. In order to take an unbiased, yet focused, approach to identify novel genes regulating vascular development, we performed a three-step ENU mutagenesis screen in zebrafish. We first screened live embryos visually, evaluating blood flow in the main trunk vessels, which form by vasculogenesis, and the intersomitic vessels, which form by angiogenesis. Embryos that displayed reduced or absent circulation were fixed and stained for endogenous alkaline phosphatase activity to reveal blood vessel morphology. All putative mutants were then crossed into the Tg(flk1:EGFP)(s843) transgenic background to facilitate detailed examination of endothelial cells in live and fixed embryos. We screened 4015 genomes and identified 30 mutations affecting various aspects of vascular development. Specifically, we identified 3 genes (or loci) that regulate the specification and/or differentiation of endothelial cells, 8 genes that regulate vascular tube and lumen formation, 8 genes that regulate vascular patterning, and 11 genes that regulate vascular remodeling, integrity and maintenance. Only 4 of these genes had previously been associated with vascular development in zebrafish illustrating the value of this focused screen. The analysis of the newly defined loci should lead to a greater understanding of vascular development and possibly provide new drug targets to treat the numerous pathologies associated with dysregulated blood vessel growth.

Chordin affects pronephros development in Xenopus embryos by anteriorizing presomitic mesoderm.

Spemann's organizer emits signals that pattern the mesodermal germ layer during Xenopus embryogenesis. In a previous study, we demonstrated that FGFR1 activity within the organizer is required for the production of both the somitic muscle- and pronephros-patterning signals by the organizer and the expression of chordin, an organizer-specific secreted protein (Mitchell and Sheets [2001] Dev. Biol. 237:295-305). Studies from others in both chicken and Xenopus embryos provide compelling evidence that pronephros forms by means of secondary induction signals emitted from anterior somites (Seufert et al. [1999] Dev. Biol. 215:233-242; Mauch et al. [2000] Dev. Biol. 220:62-75). Here we provide several lines of evidence in support of the hypothesis that chordin influences pronephros development by directing the formation of anterior somites. Chordin mRNA was absent in ultraviolet (UV) -irradiated embryos lacking pronepheros (average DAI<2) but was always found in UV-irradiated embryos that retain pronepheros (average DAI>2). Furthermore, ectopic expression of chordin in embryos and in tissue explants leads to the formation of anterior somites and pronephros. In these experiments, pronephros was only observed in association with muscle. Chordin diverted somatic muscle cells to more anterior positions within the somite file in chordin-induced secondary trunks and induced the expression of the anterior myogenic gene myf5. Finally, depletion of chordin mRNA with DEED antisense oligonucleotides substantially reduced somitic muscle and pronephric tubule and duct formation in whole embryos. These data and previous studies on ectoderm and endoderm (Sasai et al. [1995] Nature 377:757) support the idea that chordin functions as an anteriorizing signal in patterning the germ layers during vertebrate embryogenesis. Our data support the hypothesis that chordin directs the formation of anterior somites that in turn are necessary for pronephros development.

Semen displacement as a sperm competition strategy : Multiple mating, self-semen displacement, and timing of in-pair copulations.

Using a sample of 652 college students, we examined several implications of the hypothesis that the shape of the human penis evolved to enable males to substitute their semen for those of their rivals. The incidence of double mating by females appears sufficient to make semen displacement adaptive (e.g., one in four females acknowledge infidelity, one in eight admit having sex with two or more males in a 24-hour period, and one in 12 report involvement in one or more sexual threesomes with two males). We also document several changes in post-ejaculatory behavior (e.g., reduced thrusting, penis withdrawal, loss of an erection) which may have evolved to minimize displacement of the male's own semen. Consistent with predictions derived from a theoretical model (Gallup and Burch 2006), we discovered that most females report waiting at least 48 hours following an instance of infidelity before resuming sex with their in-pair partners.