Convergent extension in mammalian morphogenesis.

Convergent extension is a fundamental morphogenetic process that underlies not only the generation of the elongated vertebrate body plan from the initially radially symmetrical embryo, but also the specific shape changes characteristic of many individual tissues. These tissue shape changes are the result of specific cell behaviors, coordinated in time and space, and affected by the physical properties of the tissue. While mediolateral cell intercalation is the classic cellular mechanism for producing tissue convergence and extension, other cell behaviors can also provide similar tissue-scale distortions or can modulate the effects of mediolateral cell intercalation to sculpt a specific shape. Regulation of regional tissue morphogenesis through planar polarization of the variety of underlying cell behaviors is well-recognized, but as yet is not well understood at the molecular level. Here, we review recent advances in understanding the cellular basis for convergence and extension and its regulation.

Scribble mutation disrupts convergent extension and apical constriction during mammalian neural tube closure.

Morphogenesis of the vertebrate neural tube occurs by elongation and bending of the neural plate, tissue shape changes that are driven at the cellular level by polarized cell intercalation and cell shape changes, notably apical constriction and cell wedging. Coordinated cell intercalation, apical constriction, and wedging undoubtedly require complex underlying cytoskeletal dynamics and remodeling of adhesions. Mutations of the gene encoding Scribble result in neural tube defects in mice, however the cellular and molecular mechanisms by which Scrib regulates neural cell behavior remain unknown. Analysis of Scribble mutants revealed defects in neural tissue shape changes, and live cell imaging of mouse embryos showed that the Scrib mutation results in defects in polarized cell intercalation, particularly in rosette resolution, and failure of both cell apical constriction and cell wedging. Scrib mutant embryos displayed aberrant expression of the junctional proteins ZO-1, Par3, Par6, E- and N-cadherins, and the cytoskeletal proteins actin and myosin. These findings show that Scribble has a central role in organizing the molecular complexes regulating the morphomechanical neural cell behaviors underlying vertebrate neurulation, and they advance our understanding of the molecular mechanisms involved in mammalian neural tube closure.

CXCR4 acts as a costimulator during thymic beta-selection.

Passage through the beta-selection developmental checkpoint requires productive rearrangement of segments of the T cell antigen receptor-beta gene (Tcrb) and formation of a pre-TCR on the surface of CD4(-)CD8(-) thymocytes. How other receptors influence betabeta-selection is less well understood. Here we define a new role for the chemokine receptor CXCR4 during T cell development. CXCR4 functionally associated with the pre-TCR and influenced beta-selection by regulating the steady-state localization of immature thymocytes in thymic subregions, by facilitating optimal pre-TCR-induced survival signals, and by promoting thymocyte proliferation. We also characterize functionally relevant signaling molecules downstream of CXCR4 and the pre-TCR in thymocytes. Our data designate CXCR4 as a costimulator of the pre-TCR during beta-selection.

Tissue morphodynamics shaping the early mouse embryo.

Generation of the elongated vertebrate body plan from the initially radially symmetrical embryo requires comprehensive changes to tissue form. These shape changes are generated by specific underlying cell behaviors, coordinated in time and space. Major principles and also specifics are emerging, from studies in many model systems, of the cell and physical biology of how region-specific cell behaviors produce regional tissue morphogenesis, and how these, in turn, are integrated at the level of the embryo. New technical approaches have made it possible more recently, to examine the morphogenesis of the mouse embryo in depth, and to elucidate the underlying cellular mechanisms. This review focuses on recent advances in understanding the cellular basis for the early fundamental events that establish the basic form of the embryo.

Protein tyrosine kinase 7 is essential for tubular morphogenesis of the Wolffian duct.

The Wolffian duct, the proximal end of the mesonephric duct, undergoes non-branching morphogenesis to achieve an optimal length and size for sperm maturation. It is important to examine the mechanisms by which the developing mouse Wolffian duct elongates and coils for without proper morphogenesis, male infertility will result. Here we show that highly proliferative epithelial cells divide in a random orientation relative to the elongation axis in the developing Wolffian duct. Convergent extension (CE)-like of cell rearrangements is required for elongating the duct while maintaining a relatively unchanged duct diameter. The Wolffian duct epithelium is planar polarized, which is characterized by oriented cell elongation, oriented cell rearrangements, and polarized activity of regulatory light chain of myosin II. Conditional deletion of protein tyrosine kinase 7 (PTK7), a regulator of planar cell polarity (PCP), from mesoderm results in loss of the PCP characteristics in the Wolffian duct epithelium. Although loss of Ptk7 does not alter cell proliferation or division orientation, it affects CE and leads to the duct with significantly shortened length, increased diameter, and reduced coiling, which eventually results in loss of sperm motility, a key component of sperm maturation. In vitro experiments utilizing inhibitors of myosin II results in reduced elongation and coiling, similar to the phenotype of Ptk7 knockout. This data suggest that PTK7 signaling through myosin II regulates PCP, which in turn ensures CE-like of cell rearrangements to drive elongation and coiling of the Wolffian duct. Therefore, PTK7 is essential for Wolffian duct morphogenesis and male fertility.

Loss of Tgif function causes holoprosencephaly by disrupting the SHH signaling pathway.

Holoprosencephaly (HPE) is a severe human genetic disease affecting craniofacial development, with an incidence of up to 1/250 human conceptions and 1.3 per 10,000 live births. Mutations in the Sonic Hedgehog (SHH) gene result in HPE in humans and mice, and the Shh pathway is targeted by other mutations that cause HPE. However, at least 12 loci are associated with HPE in humans, suggesting that defects in other pathways contribute to this disease. Although the TGIF1 (TG-interacting factor) gene maps to the HPE4 locus, and heterozygous loss of function TGIF1 mutations are associated with HPE, mouse models have not yet explained how loss of Tgif1 causes HPE. Using a conditional Tgif1 allele, we show that mouse embryos lacking both Tgif1 and the related Tgif2 have HPE-like phenotypes reminiscent of Shh null embryos. Eye and nasal field separation is defective, and forebrain patterning is disrupted in embryos lacking both Tgifs. Early anterior patterning is relatively normal, but expression of Shh is reduced in the forebrain, and Gli3 expression is up-regulated throughout the neural tube. Gli3 acts primarily as an antagonist of Shh function, and the introduction of a heterozygous Gli3 mutation into embryos lacking both Tgif genes partially rescues Shh signaling, nasal field separation, and HPE. Tgif1 and Tgif2 are transcriptional repressors that limit Transforming Growth Factor ß/Nodal signaling, and we show that reducing Nodal signaling in embryos lacking both Tgifs reduces the severity of HPE and partially restores the output of Shh signaling. Together, these results support a model in which Tgif function limits Nodal signaling to maintain the appropriate output of the Shh pathway in the forebrain. These data show for the first time that Tgif1 mutation in mouse contributes to HPE pathogenesis and provide evidence that this is due to disruption of the Shh pathway.

Rac1 and Nectin3 are essential for PCP-directed axon guidance in the peripheral auditory system.

Our sense of hearing is critically dependent on the spiral ganglion neurons (SGNs) that connect the sound receptors in the organ of Corti (OC) to the cochlear nuclei of the hindbrain. Type I SGNs innervate inner hair cells (IHCs) to transmit sound signals, while type II SGNs (SGNIIs) innervate outer hair cells (OHCs) to detect moderate-to-intense sound. During development, SGNII afferents make a characteristic 90-degree turn toward the base of the cochlea and innervate multiple OHCs. It has been shown that the Planar Cell Polarity (PCP) pathway acts non-autonomously to mediate environmental cues in the cochlear epithelium for SGNII afferent turning towards the base. However, the underlying mechanisms are unknown. Here, we present evidence that PCP signaling regulates multiple downstream effectors to influence cell adhesion and the cytoskeleton in cochlear supporting cells (SCs), which serve as intermediate targets of SGNII afferents. We show that the core PCP gene Vangl2 regulates the localization of the small GTPase Rac1 and the cell adhesion molecule Nectin3 at SC-SC junctions through which SGNII afferents travel. Through in vivo genetic analysis, we also show that loss of Rac1 or Nectin3 partially phenocopied SGNII peripheral afferent turning defects in Vangl2 mutants, and that Rac1 plays a non-autonomous role in this process in part by regulating PCP protein localization at the SC-SC junctions. Additionally, epistasis analysis indicates that Nectin3 and Rac1 likely act in the same genetic pathway to control SGNII afferent turning. Together, these experiments identify Nectin3 and Rac1 as novel regulators of PCP-directed SGNII axon guidance in the cochlea.

Leucine and arginine regulate trophoblast motility through mTOR-dependent and independent pathways in the preimplantation mouse embryo.

Uterine implantation is a critical element of mammalian reproduction and is a tightly and highly coordinated event. An intricate and reciprocal uterine-embryo dialog exists to synchronize uterine receptivity with the concomitant activation of the blastocyst, maximizing implantation success. While a number of pathways involved in regulating uterine receptivity have been identified in the mouse, less is understood about blastocyst activation, the process by which the trophectoderm (TE) receives extrinsic cues that initiate new characteristics essential for implantation. Amino acids (AA) have been found to regulate blastocyst activation and TE motility in vitro. In particular, we find that arginine and leucine alone are necessary and sufficient to induce TE motility. Both arginine and leucine act individually and additively to propagate signals that are dependent on the activity of the mammalian target of rapamycin complex 1 (mTORC1). The activities of the well-established downstream targets of mTORC1, p70S6K and 4EBP, do not correlate with trophoblast motility, suggesting that an independent-rapamycin-sensitive pathway operates to induce trophoblast motility, or that other, parallel amino acid-dependent pathways are also involved. We find that endogenous uterine factors act to induce mTORC1 activation and trophoblast motility at a specific time during pregnancy, and that this uterine signal is later than the previously defined signal that induces the attachment reaction. In vivo matured blastocysts exhibit competence to respond to an 8-hour AA stimulus by activating mTOR and subsequently undergoing trophoblast outgrowth by the morning of day 4.5 of pregnancy, but not on day 3.5. By the late afternoon of day 4.5, the embryos no longer require any exposure to AA to undergo trophoblast outgrowth in vitro, demonstrating the existence and timing of an equivalent in vivo signal. These results suggest that there are two separate uterine signals regulating implantation, one that primes the embryo for the attachment reaction and another that activates mTOR and initiates invasive behavior.

Evaluating time points for measuring recovery after major trauma in adults.

OBJECTIVE: To evaluate recovery after major trauma over a 24-month time frame. BACKGROUND: Measuring disability after injury is seen as increasingly important but requires knowledge not only of the measures that should be implemented but also of the critical time points for follow-up. METHODS: Six hundred sixty-two adult major trauma patients from 2 level 1 trauma centers (October 2006 to March 2007) were followed up by telephone at 6-, 12-, 18-, and 24 months after injury. SF-12, Glasgow Outcome Scale-Extended (GOS-E), pain scores, and return to work (RTW) were collected. Multilevel mixed-effects regression models were fitted to analyze change in outcomes over time. RESULTS: Six hundred seventeen (93%) were followed up for at least 1 time point. Functional recovery (GOS-E = 8) [odds ratio (OR) 3.1, 95% CI: 1.9, 5.0] and RTW (OR 2.4, 95% CI: 1.4, 4.0) improved, and physical health (PCS-12) scores were better (mean difference 1.9, 95% CI: 0.9, 2.9), from 6 to 12 months after injury, but changed little from 12 months. Pain scores were unchanged from 6 to 12 months but were higher at 18 months than at 12 months (OR 1.8, 95% CI: 1.2, 2.8). SF-12 mental health (MCS-12) scores decreased until 18 months but improved from 18 to 24 months (mean difference 1.5, 95% CI: 0.2, 2.8). The rate of recovery differed by injury group and age. CONCLUSIONS: Different patterns of recovery were evident for each outcome, and there was a variation in the rate of recovery for some subgroups. The selection of time points for follow-up requires consideration of the outcome measurements of interest and the population being studied.

Tgif1 and Tgif2 regulate Nodal signaling and are required for gastrulation.

Tgif1 and Tgif2 are transcriptional co-repressors that limit the response to TGFbeta signaling and play a role in regulating retinoic-acid-mediated gene expression. Mutations in human TGIF1 are associated with holoprosencephaly, but it is unclear whether this is a result of deregulation of TGFbeta/Nodal signaling, or of effects on other pathways. Surprisingly, mutation of Tgif1 in mice results in only relatively mild developmental phenotypes in most strain backgrounds. Here, we show that loss-of-function mutations in both Tgif1 and Tgif2 result in a failure of gastrulation. By conditionally deleting Tgif1 in the epiblast, we demonstrate that a single wild-type allele of Tgif1 in the extra-embryonic tissue allows the double null embryos to gastrulate and begin organogenesis, suggesting that extra-embryonic Tgif function is required for patterning the epiblast. Genetically reducing the dose of Nodal in embryos lacking all Tgif function results in partial rescue of the gastrulation defects. Conditional double null embryos have defects in left-right asymmetry, which are also alleviated by reducing the dose of Nodal. Together, these data show that Tgif function is required for gastrulation, and provide the first clear evidence that Tgifs limit the transcriptional response to Nodal signaling during early embryogenesis.

Patient perspectives of care in a regionalised trauma system: lessons from the Victorian State Trauma System.

OBJECTIVES: To explore injured patients' experiences of trauma care to identify areas for improvement in service delivery. DESIGN, SETTING AND PARTICIPANTS: Qualitative study using in-depth, semi-structured interviews, conducted from 1 April 2011 to 31 January 2012, with 120 trauma patients registered by the Victorian State Trauma Registry and the Victorian Orthopaedic Trauma Outcomes Registry and managed at the major adult trauma services (MTS) in Victoria. MAIN OUTCOME MEASURES: Emergent themes from patients' experiences of acute, rehabilitation and post-discharge care in the Victorian State Trauma System (VSTS). RESULTS: Patients perceived their acute hospital care as high quality, although 3s with communication and surgical management delays were common. Discharge from hospital was perceived as stressful, and many felt ill prepared for discharge. A consistent emerging theme was the sense of a lack of coordination of post-discharge care, and the absence of a consistent point of contact for ongoing management. Most patients' primary point of contact after discharge was outpatient clinics at the MTS, which were widely criticised because of substantial delays in receiving an appointment, prolonged waiting times, limited time with clinicians, lack of continuity of care and inability to see senior clinicians. CONCLUSIONS: This study highlights perceived 3s in the patient care pathway in the VSTS, especially those relating to communication, information provision and post-discharge care. Trauma patients perceived the need for a single point of contact for coordination of post-discharge care.

Does recall of preinjury disability change over time?

BACKGROUND: Pre-injury disability must be determined when assessing whether treatment programs return people to pre-injury status, however there is little empirical evidence to support recommendations that this be done as soon as possible after injury to prevent recall bias. OBJECTIVES: To determine disagreement between recall of pre-injury disability at different time points post-injury and bias towards under- or overestimating pre-injury disability. METHODS: Self-reported pre-injury global disability was assessed within days, 6 months and 12 months post-injury in patients admitted to two level 1 adult trauma centres. Kappa statistics and multiple logistic regression models identified predictors of disagreement between time-points. RESULTS: Pre-injury disability was measured at all time-points in 801 patients. Pre-injury disability at baseline was rated as none, mild, moderate, marked and severe in 80%, 12%, 5.1%, 1.9% and 1.0% respectively. Absolute agreement between baseline and 6 and 12 months respectively, was 79% and 80%. Corresponding kappa values (95% confidence intervals) were 0.33 (0.26-0.40) and 0.32 (0-25-0.38). Patients over 65 years or not completing high school were more likely to report less pre-injury disability at 6 and 12 months than at baseline with adjusted odds ratios (95% confidence intervals) for these groups being 8.24 (4.32-15.72) and 1.93 (1.03-3.64) respectively. CONCLUSIONS: There was little evidence of recall bias in an adult trauma population if self-reported global pre-injury disability was assessed 6 months post-injury. The recall of pre-injury disability up to 6 months post-injury can be used to determine return to pre-injury status, if assessment is not feasible shortly after injury.

Mouse primitive streak forms in situ by initiation of epithelial to mesenchymal transition without migration of a cell population.

BACKGROUND: During gastrulation, an embryo acquires the three primordial germ layers that will give rise to all of the tissues in the body. In amniote embryos, this process occurs via an epithelial to mesenchymal transition (EMT) of epiblast cells at the primitive streak. Although the primitive streak is vital to development, many aspects of how it forms and functions remain poorly understood. RESULTS: Using live, 4 dimensional imaging and immunohistochemistry, we have shown that the posterior epiblast of the pre-streak murine embryo does not display convergence and extension behavior or large scale migration or rearrangement of a cell population. Instead, the primitive streak develops in situ and elongates by progressive initiation EMT in the posterior epiblast. Loss of basal lamina (BL) is the first step of this EMT, and is strictly correlated with ingression of nascent mesoderm. Once the BL is lost in a given region, cells leave the epiblast by apical constriction in order to enter the primitive streak. CONCLUSIONS: This is the first description of dynamic cell behavior during primitive streak formation in the mouse embryo, and reveals mechanisms that are quite distinct from those observed in other amniote model systems. Unlike chick and rabbit, the murine primitive streak arises in situ by progressive initiation of EMT beginning in the posterior epiblast, without large-scale movement or convergence and extension of epiblast cells.

Improved functional outcomes for major trauma patients in a regionalized, inclusive trauma system.

OBJECTIVE: To describe outcomes of major trauma survivors managed in an organized trauma system, including the association between levels of care and outcomes over time. BACKGROUND: Trauma care systems aim to reduce deaths and disability. Studies have found that regionalization of trauma care reduces mortality but the impact on quality of survival is unknown. Evaluation of a trauma system should include mortality and morbidity. METHODS: Predictors of 12-month functional (Glasgow Outcome Scale-Extended) outcomes after blunt major trauma (Injury Severity Score >15) in an organized trauma system were explored using ordered logistic regression for the period October 2006 to June 2009. Data from the population-based Victorian State Trauma Registry were used. RESULTS: There were 4986 patients older than 18 years. In-hospital mortality decreased from 11.9% in 2006-2007 to 9.9% in 2008-2009. The follow-up rate at 12 months was 86% (n = 3824). Eighty percent reported functional limitations. Odds of better functional outcome increased in the 2007-2008 [adjusted odds ratio (AOR): 1.22; 95% CI: 1.05, 1.41] and 2008-2009 (AOR: 1.16; 95% CI: 1.01, 1.34) years compared with 2006-2007. Cases managed at major trauma services (MTS) achieved better functional outcome (AOR: 1.22; 95% CI: 1.03, 1.45). Female gender, older age, and lower levels of education demonstrated lower adjusted odds of better outcome. CONCLUSIONS: Despite an annual decline in mortality, risk-adjusted functional outcomes improved over time, and cases managed at MTS (level-1 trauma centers) demonstrated better functional outcomes. The findings provide early evidence that this inclusive, regionalized trauma system is achieving its aims.

Cell-cell adhesion defects in Mrj mutant trophoblast cells are associated with failure to pattern the chorion during early placental development.

Early placental development in mice involves patterning of the chorion into distinct layers, though little is understood regarding the interactions that regulate its organization. Here we demonstrate that keratin aggregates found in Mrj(-/-) chorionic trophoblast cells are associated with abnormal cell morphology, collapse of the actin cytoskeleton, E-cadherin and ß-catenin misexpression and extracellular matrix (ECM) disorganization. Accordingly, Mrj(-/-) trophoblast cells in vitro are nonadherent and display erratic migratory behavior. These cells also fail to differentiate into syncytiotrophoblast cells since Rhox4b expression, a marker of syncytiotrophoblast progenitors, was maintained and Gcm1, Synb, and Syna expression failed to increase. This differentiation defect was not solely attributable to E-cadherin misexpression or ECM disorganization. However, plating Mrj-deficient cells on exogenous laminin-511 normalized their cell behavior. Lastly, we show that Mrj(-/-) chorions at embryonic day 8.5 have expanded Rhox4b expression domains and do not form normal layers of gene expression suggesting that chorion patterning requires Mrj.

Comparing the responsiveness of functional outcome assessment measures for trauma registries.

BACKGROUND: Measuring long-term disability and functional outcomes after major trauma is not standardized across trauma registries. An ideal measure would be responsive to change but not have significant ceiling effects. The aim of this study was to compare the responsiveness of the Glasgow Outcome Scale (GOS), GOS-Extended (GOSE), Functional Independence Measure (FIM), and modified FIM in major trauma patients, with and without significant head injuries. METHODS: Patients admitted to two adult Level I trauma centers in Victoria, Australia, who survived to discharge from hospital, were aged 15 years to 80 years with a blunt mechanism of injury, and had an estimated Injury Severity Score >15 on admission, were recruited for this prospective study. The instruments were administered at baseline (hospital discharge) and by telephone interview 6 months after injury. Measures of responsiveness, including effect sizes, were calculated. Bootstrapping techniques, and floor and ceiling effects, were used to compare the measures. RESULTS: Two hundred forty-three patients participated, of which 234 patients (96%) completed the study. The GOSE and GOS were the most responsive instruments in this major trauma population with effect sizes of 5.3 and 4.4, respectively. The GOSE had the lowest ceiling effect (17%). CONCLUSIONS: The GOSE was the instrument with greatest responsiveness and the lowest ceiling effect in a major trauma population with and without significant head injuries and is recommended for use by trauma registries for monitoring functional outcomes and benchmarking care. The results of this study do not support the use of the modified FIM for this purpose.

Functional and health-related quality of life outcomes after pediatric trauma.

BACKGROUND: Pediatric trauma results in lower mortality than adults and a high potential for lifelong functional impairment and reduced health-related quality of life (HRQL). There is no consensus regarding the best approach to measuring outcomes in this group. METHODS: One hundred and fifty injured children admitted to a pediatric trauma center participated in this study. The Pediatric Quality of Life Inventory (PedsQL), Child Health Questionnaire (CHQ-PF28), King's Outcome Scale for Childhood Head Injury (KOSCHI), modified Glasgow Outcome Scale (mGOS), and the Functional Independence Measure (FIM) were administered at 1 month, 6 months, and 12 months after injury by telephone. Change in instrument scores was assessed using multilevel mixed effects models. Mean HRQL scores were compared with population norms for the CHQ-PF28 and with healthy children for the PedsQL. RESULTS: Follow-up at all time points was completed for 144 (96%) cases. The median injury severity score was 10, and 65% of the patients enrolled were men. At 12 months, the percentage of cases with ongoing disability was 14% for the FIM, 61% using the mGOS, and 58% for the KOSCHI. CHQ-PF28 physical and PedsQL psychosocial health scores were below healthy child norms at 12 months. Improvement across all time points was demonstrated for the KOSCHI, mGOS, CHQ-PF28 physical, and PedsQL psychosocial summary scores. CONCLUSIONS: Seriously injured children showed ongoing disability and reduced HRQL 12 months after injury. The CHQ-PF28 and PedsQL, and the mGOS and KOSCHI, performed comparably. The FIM demonstrated considerable ceiling effects, and improvement over time was not shown. The results inform the methodology of pediatric outcomes studies and protocol development for the routine follow-up of pediatric trauma patients.

The primitive streak and cellular principles of building an amniote body through gastrulation.

The primitive streak, a transient embryonic structure, marks bilateral symmetry in mammalian and avian embryos and helps confer anterior-posterior and dorsal-ventral spatial information to early differentiating cells during gastrulation. Its recapitulation in vitro may facilitate derivation of tissues and organs with in vivo­like complexity. Proper understanding of the primitive streak and what it entails in human development is key to achieving such research objectives. Here we provide an overview of the primitive streak and conclude that this structure is neither conserved nor necessary for gastrulation or early lineage diversification. We offer a model in which the primitive streak is viewed as part of a morphologically diverse yet molecularly conserved process of spatial coordinate acquisition. We predict that recapitulation of the primitive streak is dispensable for development in vitro.

Agreement between parent and child report of health-related quality of life: impact of time postinjury.

BACKGROUND: Health-related quality of life (HRQL) is subjective concept and, therefore, should be captured directly from the patient. However, proxy reporting of HRQL is widespread, particularly in pediatric studies where children have been considered unreliable respondents. This study assessed the level of agreement between proxy (parent) and child reports of HRQL at key time points after injury. METHODS: Thirty-seven seriously injured children aged 13 years to 16 years participated in this study. The Pediatric Quality of Life inventory was administered to the parent and child at 1 month, 6 months, and 12 months after injury by telephone interview. Agreement between child and parent responses was compared using Bland-Altman plots, and Pediatric Quality of Life inventory physical and psychosocial summary scales were compared using paired t tests or Wilcoxon signed-rank tests, respectively. RESULTS: At 1-month (psychosocial t = -4.6, p < 0.001; physical t = -6.5 p < 0.001) and 6-month (psychosocial z = -2.5, p = 0.01; physical z = -2.6, p = 0.01) postinjury there was a significant difference between the parent and child reports, with children rating their HRQL higher than their parents. At 12-months, there was no difference between the scores reported by parents and their children (psychosocial z = -0.3, p = 0.76; physical t = -0.7, p = 0.51). CONCLUSIONS: Agreement between parent and child ratings of HRQL improved with time postinjury. The findings have implications for the design of pediatric trauma outcomes studies and the routine collection of pediatric HRQL data. Parent and child reports should be considered separate but important information, particularly in the early stages following injury. Where collection of both is not feasible, parent or child report should be chosen, and interchangeable use of parent and child reports limited.