Clade-wide variation in bite-force performance is determined primarily by size, not ecology

Performance traits are tightly linked to the fitness of organisms. However, because studies of variation in performance traits generally focus on just one or several closely related species, we are unable to draw broader conclusions about how and why these traits vary across clades. One important performance trait related to many aspects of an animal's life history is bite-force. Here, we use a clade-wide phylogenetic comparative approach to investigate relationships between size, head dimensions and bite-force among lizards and tuatara (lepidosaurs), using the largest bite-force dataset collated to date for any taxonomic group. We test four predictions: that bite-force will be greater in larger species, and for a given body size, bite-force will be greatest in species with acrodont tooth attachment, herbivorous diets, and non-burrowing habits. We show that bite-force is strongly related to body and head size across lepidosaurs and, as predicted, larger species have the greatest bite-forces. Contrary to our other predictions, tooth attachment, diet and habit have little predictive power when accounting for size. Herbivores bite more forcefully simply because they are larger. Our results also highlight priorities for future sampling to further enhance our understanding of broader evolutionary patterns

Middle Jurassic fossils document an early stage in salamander evolution

Salamanders are an important group of living amphibians and model organisms for understanding locomotion, development, regeneration, feeding, and toxicity in tetrapods. However, their origin and early radiation remain poorly understood, with early fossil stem-salamanders so far represented by larval or incompletely known taxa. This poor record also limits understanding of the origin of Lissamphibia (i.e., frogs, salamanders, and caecilians). We report fossils from the Middle Jurassic of Scotland representing almost the entire skeleton of the enigmatic stem-salamander Marmorerpeton. We use computed tomography to visualize high-resolution three-dimensional anatomy, describing morphologies that were poorly characterized in early salamanders, including the braincase, scapulocoracoid, and lower jaw. We use these data in the context of a phylogenetic analysis intended to resolve the relationships of early and stem-salamanders, including representation of important outgroups alongside data from high-resolution imaging of extant species. Marmorerpeton is united with Karaurus, Kokartus, and others from the Middle Jurassic–Lower Cretaceous of Asia, providing evidence for an early radiation of robustly built neotenous stem-salamanders. These taxa display morphological specializations similar to the extant cryptobranchid “giant” salamanders. Our analysis also demonstrates stem-group affinities for a larger sample of Jurassic species than previously recognized, highlighting an unappreciated diversity of stem-salamanders and cautioning against the use of single species (e.g., Karaurus) as exemplars for stem-salamander anatomy. These phylogenetic findings, combined with knowledge of the near-complete skeletal anatomy of Mamorerpeton, advance our understanding of evolutionary changes on the salamander stem-lineage and provide important data on early salamanders and the origins of Batrachia and Lissamphibia

The biomechanical role of the chondrocranium and the material properties of cartilage

The chondrocranium is the cartilage component of the vertebrate braincase. Among jawed vertebrates it varies greatly in structure, mineralisation, and in the extent to which it is replaced by bone during development. In mammals, birds, and some bony fish, most of the chondrocranium is replaced by bone whereas in lizards, amphibians, and chondrichthyan fish it may remain a significant part of the braincase complex in adulthood. To what extent this variation relates to differences in skull biomechanics is poorly understood. However, there have been examinations of chondrocranium histology, in vivo strain, and impact on rostrum growth following partial removal of the chondrocranium. These studies have led to suggestions that the chondrocranium may provide structural support or serve to dampen external loads. Advances in computing-power have also facilitated an increase in the number of three-dimensional computer-based models. These models can be analysed (in silico) to test specific biomechanical hypotheses under specified loading conditions. However, representing the material properties of cartilage is still problematic because these properties differ according to the speed and direction of loading. The relationship between stress and strain is also non-linear. Nevertheless, analyses to date suggest that the chondrocranium does not provide a vertical support in lizards but it may serve to absorb some loads in humans. We anticipate that future models will include ever more detailed representations of the loading, anatomy, and material properties, in tandem with rigorous forms of model validation. However, comparison among a wider range of vertebrate subjects should also be pursued, in particular larvae, juveniles, and very small adult animals

How can the practice nurse be more involved in the care of the chronically ill? The perspectives of GPs, patients and practice nurses

BACKGROUND: A well established "midlevel" of patient care, such as nurse practitioners and/or physician assistants, exits in many countries like the US, Canada, and Australia. In Germany, however there is only one kind of profession assisting the physician in practices, the practice nurse. Little is known about the present involvement of practice nurses in patients' care in Germany and about the attitudes of GPs, assistants and patients concerning an increased involvement. The aim of our study was to get qualitative information on the extent to which practice nurses are currently involved in the treatment of patients and about possibilities of increased involvement as well as on barriers of increased involvement. METHODS: We performed qualitative, semi-structured interviews with 20 GPs, 20 practice nurses and 20 patients in the Heidelberg area. The interviews were digitally recorded, transcribed and content-analysed with ATLAS.ti. RESULTS: Practice nurses are only marginally involved in the treatment of patients. GPs as well as patients were very sceptical about increased involvement in care. Patients were sceptical about nurses' professional background and feared a worsening of the patient doctor relationship. GPs also complained about the nurses' deficient education concerning medical knowledge. They feared a lack of time as well as a missing reimbursement for the efforts of an increased involvement. Practice nurses were mostly willing to be more involved, regarding it as an appreciation of their role. Important barriers were lack of time, overload with administrative work, and a lack of professional knowledge. CONCLUSION: Practice nurses were only little involved in patient care. GPs were more sceptical than patients regarding an increased involvement. One possible area, accepted by all interviewed groups, was patient education as for instance dietary counselling. New treatment approaches as the chronic care model will require a team approach which currently only marginally exists in the German health care system. Better medical education of practice nurses is indispensable, but GPs also have to accept that they cannot fulfil the requirement of future care alone

Recurrent somatic alterations of FGFR1 and NTRK2 in pilocytic astrocytoma

Pilocytic astrocytoma, the most common childhood brain tumor(1), is typically associated with mitogen-activated protein kinase (MAPK) pathway alterations(2). Surgically inaccessible midline tumors are therapeutically challenging, showing sustained tendency for progression(3) and often becoming a chronic disease with substantial morbidities(4). Here we describe whole-genome sequencing of 96 pilocytic astrocytomas, with matched RNA sequencing (n=73), conducted by the International Cancer Genome Consortium (ICGC) PedBrain Tumor Project. We identified recurrent activating mutations in FGFR1 and PTPN11 and novel NTRK2 fusion genes in non-cerebellar tumors. New BRAF activating changes were also observed. MAPK pathway alterations affected 100% of tumors analyzed, with no other significant mutations, indicating pilocytic astrocytoma as predominantly a single-pathway disease. Notably, we identified the same FGFR1 mutations in a subset of H3F3A-mutated pediatric glioblastoma with additional alterations in NF1(5). Our findings thus identify new potential therapeutic targets in distinct subsets of pilocytic astrocytoma and childhood glioblastoma