Access to preventive health services of migrants in five EU countries

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A mathematical model for mechanotransduction at the early steps of suture formation

Growth and patterning of craniofacial sutures are subjected to the effects of mechanical stress. Mechanotransduction processes occurring at the margins of the sutures are not precisely understood. Here, we propose a simple theoretical model based on the orientation of collagen fibres within the suture in response to local stress. We demonstrate that fibre alignment generates an instability leading to the emergence of interdigitations. We confirm the appearance of this instability both analytically and numerically. To support our model, we use histology and synchrotron x-ray microtomography and reveal the fine structure of fibres within the sutural mesenchyme and their insertion into the bone. Furthermore, using a mouse model with impaired mechanotransduction, we show that the architecture of sutures is disturbed when forces are not interpreted properly. Finally, by studying the structure of sutures in the mouse, the rat, an actinopterygian (\emph{Polypterus bichir}) and a placoderm (\emph{Compagopiscis croucheri}), we show that bone deposition patterns during dermal bone growth are conserved within jawed vertebrates. In total, these results support the role of mechanical constraints in the growth and patterning of craniofacial sutures, a process that was probably effective at the emergence of gnathostomes, and provide new directions for the understanding of normal and pathological suture fusion

Sponge grade body fossil with cellular resolution dating 60 Myr before the Cambrian

An extraordinarily well preserved, 600-million-year (Myr)-old, three-dimensionally phosphatized fossil displaying multiple independent characters of modern adult sponges has been analyzed by SEM and synchrotron X-ray tomography. The fossilized animal (Eocyathispongia qiania gen. et sp. nov.) is slightly more than 1.2 mm wide and 1.1 mm tall, is composed of hundreds of thousands of cells, and has a gross structure consisting of three adjacent hollow tubes sharing a common base. The main tube is crowned with a large open funnel, and the others end in osculum-like openings to the exterior. The external surface is densely covered with flat tile-like cells closely resembling sponge pinacocytes, and this layer is punctuated with smaller pores. A dense patch of external structures that display the form of a lawn of sponge papillae has also survived. Within the main funnel, an area where features of the inner surface are preserved displays a regular pattern of uniform pits. Many of them are surrounded individually by distinct collars, mounted in a supporting reticulum. The possibility cannot be excluded that these pits are the remains of a field of choanocytes. The character set evinced by this specimen, ranging from general anatomy to cell type, uniquely indicates that this specimen is a fossil of probable poriferan affinity. So far, we have only this single specimen, and although its organized and complex cellular structure precludes any reasonable interpretation that its origin is abiogenic, confirmation that it is indeed a fossilized sponge will clearly require discovery of additional specimens

Contribution of chronic diseases to the disability burden in a population 15 years and older, Belgium, 1997-2008.

BACKGROUND: Age-associated disability reduces quality of life in older populations and leads to wide-range implications for social and health policy. The identification of diseases that contribute to the disability burden is crucial to the development of prevention and intervention strategies to reduce disability. In this study, we assessed the contribution of chronic diseases to the prevalence of disability in Belgium. METHODS: Data from 35,837 individuals aged 15 years or older who participated in the 1997, 2001, 2004, or 2008 Belgian Health Interview Surveys were used. Disability was defined as difficulties in doing at least one of six activities of daily living (transfer in and out of bed, transfer in and out of chair, dressing, washing hands and face, feeding, and going to the toilet) and/or mobility limitations (ability to walk without stopping less than 200 m). Multiple additive regression models were fitted separately for men and women to estimate the age-specific background disability rate (experienced by everyone, independent of the presence of specific diseases) and disease-specific disability rates (disability rate in subjects who reported selected chronic diseases). RESULTS: Musculoskeletal, cardiovascular, and respiratory diseases were the main contributors to the disability burden in Belgium. Musculoskeletal diseases were the most prevalent diseases in men and women in all age groups. Neurological diseases and stroke were the most disabling diseases, i.e. caused the highest level of disability among the diseased individuals, in all age groups for men and women, respectively. Back pain was the main cause of disability in men aged 15 to 64 years, while heart attack was the major contributor to the disability prevalence in men aged 65 or older. Likewise, arthritis was the main cause of disability among women across all age groups. Depression was also an important contributor in young subjects (15-54 years). Cancer was not an important contributor to the disability prevalence in Belgium. CONCLUSIONS: To reduce the burden of disability in Belgium, interventions should target musculoskeletal, cardiovascular and respiratory diseases especially among elderly. Furthermore, attention should also be given to depression in young individuals

Contribution of chronic diseases to the disability burden in a population 15 years and older, Belgium, 1997-2008

Background: Age-associated disability reduces quality of life in older populations and leads to wide-range implications for social and health policy. The identification of diseases that contribute to the disability burden is crucial to the development of prevention and intervention strategies to reduce disability. In this study, we assessed the contribution of chronic diseases to the prevalence of disability in Belgium. Methods: Data from 35,837 individuals aged 15 years or older who participated in the 1997, 2001, 2004, or 2008 Belgian Health Interview Surveys were used. Disability was defined as difficulties in doing at least one of six activities of daily living (transfer in and out of bed, transfer in and out of chair, dressing, washing hands and face, feeding, and going to the toilet) and/or mobility limitations (ability to walk without stopping less than 200 m). Multiple additive regression models were fitted separately for men and women to estimate the age-specific background disability rate (experienced by everyone, independent of the presence of specific diseases) and disease-specific disability rates (disability rate in subjects who reported selected chronic diseases). Results: Musculoskeletal, cardiovascular, and respiratory diseases were the main contributors to the disability burden in Belgium. Musculoskeletal diseases were the most prevalent diseases in men and women in all age groups. Neurological diseases and stroke were the most disabling diseases, i.e. caused the highest level of disability among the diseased individuals, in all age groups for men and women, respectively. Back pain was the main cause of disability in men aged 15 to 64 years, while heart attack was the major contributor to the disability prevalence in men aged 65 or older. Likewise, arthritis was the main cause of disability among women across all age groups. Depression was also an important contributor in young subjects (15-54 years). Cancer was not an important contributor to the disability prevalence in Belgium. Conclusions: To reduce the burden of disability in Belgium, interventions should target musculoskeletal, cardiovascular and respiratory diseases especially among elderly. Furthermore, attention should also be given to depression in young individuals

Dental evidence for ontogenetic differences between modern humans and Neanderthals

Humans have an unusual life history, with an early weaning age, long childhood, late first reproduction, short interbirth intervals, and long lifespan. In contrast, great apes wean later, reproduce earlier, and have longer intervals between births. Despite 80 y of speculation, the origins of these developmental patterns in Homo sapiens remain unknown. Because they record daily growth during formation, teeth provide important insights, revealing that australopithecines and early Homo had more rapid ontogenies than recent humans. Dental development in later Homo species has been intensely debated, most notably the issue of whether Neanderthals and H. sapiens differ. Here we apply synchrotron virtual histology to a geographically and temporally diverse sample of Middle Paleolithic juveniles, including Neanderthals, to assess tooth formation and calculate age at death from dental microstructure. We find that most Neanderthal tooth crowns grew more rapidly than modern human teeth, resulting in significantly faster dental maturation. In contrast, Middle Paleolithic H. sapiens juveniles show greater similarity to recent humans. These findings are consistent with recent cranial and molecular evidence for subtle developmental differences between Neanderthals and H. sapiens. When compared with earlier hominin taxa, both Neanderthals and H. sapiens have extended the duration of dental development. This period of dental immaturity is particularly prolonged in modern humans.Human Evolutionary Biolog

Contribution of chronic diseases to the mild and severe disability burden in Belgium

Background: Population aging accompanied by an increased longevity with disability has raised international concern, especially due to its costs to the health care systems. Chronic diseases are the main causes of physical disability and their simultaneous occurrence in the population can impact the disablement process, resulting in different severity levels. In this study, the contribution of chronic diseases to both mild and severe disability burden in Belgium was investigated. Methods: Data on 21 chronic diseases and disability from 35,799 individuals aged 15years or older who participated in the 1997, 2001, 2004, or 2008 Belgian Health Interview Surveys were analysed. Mild and severe disability were defined based on questions related to six activities of daily living and/or mobility limitations. To attribute disability by severity level to selected chronic diseases, multiple additive hazard models were fitted to each disability outcome, separately for men and women. Results: A stable prevalence of mild (5%) and severe (2-3%) disability was observed for the Belgian population aged 15years or older between 1997 and 2008. Arthritis was the most important contributor in women with mild and severe disability. In men, low back pain and chronic respiratory diseases contributed most to the mild and severe disability burden, respectively. The contribution also differed by age: for mild disability, depression and chronic respiratory diseases were important contributors among young individuals, while heart attack had a large contribution for older individuals. For severe disability, neurological diseases and stroke presented a large contribution in young and elderly individuals, respectively. Conclusions: Our results indicate that the assessment of the contribution of chronic diseases on disability is more informative if different levels of disability are taken into consideration. The identification of diseases which are related to different levels of disability - mild and severe - can assist policymakers in the definition and prioritisation of strategies to tackle disability, involving prevention, rehabilitation programs, support services, and training for disabled individuals

Preparation of large biological samples for high-resolution, hierarchical, synchrotron phase-contrast tomography with multimodal imaging compatibility

Imaging across different scales is essential for understanding healthy organ morphology and pathophysiological changes. The macro- and microscale three-dimensional morphology of large samples, including intact human organs, is possible with X-ray microtomography (using laboratory or synchrotron sources). Preparation of large samples for high-resolution imaging, however, is challenging due to limitations such as sample shrinkage, insufficient contrast, movement of the sample and bubble formation during mounting or scanning. Here, we describe the preparation, stabilization, dehydration and mounting of large soft-tissue samples for X-ray microtomography. We detail the protocol applied to whole human organs and hierarchical phase-contrast tomography at the European Synchrotron Radiation Facility, yet it is applicable to a range of biological samples, including complete organisms. The protocol enhances the contrast when using X-ray imaging, while preventing sample motion during the scan, even with different sample orientations. Bubbles trapped during mounting and those formed during scanning (in the case of synchrotron X-ray imaging) are mitigated by multiple degassing steps. The sample preparation is also compatible with magnetic resonance imaging, computed tomography and histological observation. The sample preparation and mounting require 24-36 d for a large organ such as a whole human brain or heart. The preparation time varies depending on the composition, size and fragility of the tissue. Use of the protocol enables scanning of intact organs with a diameter of 150 mm with a local voxel size of 1 μm. The protocol requires users with expertise in handling human or animal organs, laboratory operation and X-ray imaging

Neurocranial development of the coelacanth and the evolution of the sarcopterygian head

The neurocranium of sarcopterygian fishes was originally divided into an anterior (ethmosphenoid) and posterior (otoccipital) portion by an intracranial joint, and underwent major changes in its overall geometry before fusing into a single unit in lungfishes and early tetrapods. Although the pattern of these changes is well-documented, the developmental mechanisms that underpin variation in the form of the neurocranium and its associated soft tissues during the evolution of sarcopterygian fishes remain poorly understood. The coelacanth Latimeria is the only known living vertebrate that retains an intracranial joint. Despite its importance for understanding neurocranial evolution, the development of the neurocranium of this ovoviviparous fish remains unknown. Here we investigate the ontogeny of the neurocranium and brain in Latimeria chalumnae using conventional and synchrotron X-ray microcomputed tomography as well as magnetic resonance imaging, performed on an extensive growth series for this species. We describe the neurocranium at the earliest developmental stage known for Latimeria, as well as the major changes that the neurocranium undergoes during ontogeny. Changes in the neurocranium are associated with an extreme reduction in the relative size of the brain along with an enlargement of the notochord. The development of the notochord appears to have a major effect on the surrounding cranial components, and might underpin the formation of the intracranial joint. Our results shed light on the interplay between the neurocranium and its adjacent soft tissues during development in Latimeria, and provide insights into the developmental mechanisms that are likely to have underpinned the evolution of neurocranial diversity in sarcopterygian fishes

Synchrotron imaging of dentition provides insights into the biology of Hesperornis and Ichthyornis, the "last" toothed birds.

BACKGROUND: The dentitions of extinct organisms can provide pivotal information regarding their phylogenetic position, as well as paleobiology, diet, development, and growth. Extant birds are edentulous (toothless), but their closest relatives among stem birds, the Cretaceous Hesperornithiformes and Ichthyornithiformes, retained teeth. Despite their significant phylogenetic position immediately outside the avian crown group, the dentitions of these taxa have never been studied in detail. To obtain new insight into the biology of these 'last' toothed birds, we use cutting-edge visualisation techniques to describe their dentitions at unprecedented levels of detail, in particular propagation phase contrast x-ray synchrotron microtomography at high-resolution. RESULTS: Among other characteristics of tooth shape, growth, attachment, implantation, replacement, and dental tissue microstructures, revealed by these analyses, we find that tooth morphology and ornamentation differ greatly between the Hesperornithiformes and Ichthyornithiformes. We also highlight the first Old World, and youngest record of the major Mesozoic clade Ichthyornithiformes. Both taxa exhibit extremely thin and simple enamel. The extension rate of Hesperornis tooth dentine appears relatively high compared to non-avian dinosaurs. Root attachment is found for the first time to be fully thecodont via gomphosis in both taxa, but in Hesperornis secondary evolution led to teeth implantation in a groove, at least locally without a periodontal ligament. Dental replacement is shown to be lingual via a resorption pit in the root, in both taxa. CONCLUSIONS: Our results allow comparison with other archosaurs and also mammals, with implications regarding dental character evolution across amniotes. Some dental features of the 'last' toothed birds can be interpreted as functional adaptations related to diet and mode of predation, while others appear to be products of their peculiar phylogenetic heritage. The autapomorphic Hesperornis groove might have favoured firmer root attachment. These observations highlight complexity in the evolutionary history of tooth reduction in the avian lineage and also clarify alleged avian dental characteristics in the frame of a long-standing debate on bird origins. Finally, new hypotheses emerge that will possibly be tested by further analyses of avian teeth, for instance regarding dental replacement rates, or simplification and thinning of enamel throughout the course of early avian evolution