Penetrating neck injuries: a guide to evaluation and management.

Introduction Penetrating neck injury is a relatively uncommon trauma presentation with the potential for significant morbidity and possible mortality. There are no international consensus guidelines on penetrating neck injury management and published reviews tend to focus on traditional zonal approaches. Recent improvements in imaging modalities have altered the way in which penetrating neck injuries are now best approached with a more conservative stance. A literature review was completed to provide clinicians with a current practice guideline for evaluation and management of penetrating neck injuries. Methods A comprehensive MEDLINE (PubMed) literature search was conducted using the search terms 'penetrating neck injury', 'penetrating neck trauma', 'management', 'guidelines' and approach. All articles in English were considered. Articles with only limited relevance to the review were subsequently discarded. All other articles which had clear relevance concerning the epidemiology, clinical features and surgical management of penetrating neck injuries were included. Results After initial resuscitation with Advanced Trauma Life Support principles, penetrating neck injury management depends on whether the patient is stable or unstable on clinical evaluation. Patients whose condition is unstable should undergo immediate operative exploration. Patients whose condition is stable who lack hard signs should undergo multidetector helical computed tomography with angiography for evaluation of the injury, regardless of the zone of injury. Conclusions The 'no zonal approach' to penetrating neck trauma is a selective approach with superior patient outcomes in comparison with traditional management principles. We present an evidence-based, algorithmic and practical guide for clinicians to use when assessing and managing penetrating neck injury.

A new view of patterning domains in the vertebrate mesoderm.

The musculoskeletal system of vertebrates is derived from the embryonic mesoderm. Its structures are categorized as epaxial or hypaxial based on their adult position and innervation. The epaxial/hypaxial terminology is also used to describe regions of the embryonic somites based on fate mapping of somitic derivatives. However, the adult, functional distinctions are not fully consistent with the changing embryonic environments of mesodermal populations during morphogenesis, and the traditional terminology loses accuracy when used to describe certain mutant phenotypes. Here we describe a new terminology naming two mesodermal environments defined by the lineage of the included cells. We discuss how mutant phenotypes may be better explained by consideration of the embryonic context in which genes take their effect and argue that the recognition of these embryonic territories clarifies description and discussion of the morphogenesis and patterning of the musculoskeletal system.

Assembly of trunk and limb blood vessels involves extensive migration and vasculogenesis of somite-derived angioblasts.

Vascular development requires the assembly of precursor cells into blood vessels, but how embryonic vessels are assembled is not well understood. To determine how vascular cells migrate and assemble into vessels of the trunk and limb, marked somite-derived angioblasts were followed in developing embryos. Injection of avian somites with the cell-tracker DiI showed that somite-derived angioblasts in unperturbed embryos migrated extensively and contributed to trunk and limb vessels. Mouse-avian chimeras with mouse presomitic mesoderm grafts had graft-derived endothelial cells in blood vessels at significant distances from the graft, indicating that mouse angioblasts migrated extensively in avian hosts. Mouse graft-derived endothelial cells were consistently found in trunk vessels, such as the perineural vascular plexus, the cardinal vein, and presumptive intersomitic vessels, as well as in vessels of the limb and kidney rudiment. This reproducible pattern of graft colonization suggests that avian vascular patterning cues for trunk and limb vessels are recognized by mammalian somitic angioblasts. Mouse-quail chimeras stained with both the quail vascular marker QH1 and the mouse vascular marker PECAM-1 had finely chimeric vessels, with graft-derived mouse cells interdigitated with quail vascular cells in most vascular beds colonized by graft cells. Thus, diverse trunk and limb blood vessels have endothelial cells that developed from migratory somitic angioblasts, and assembly of these vessels is likely to have a large vasculogenic component.

Hox genes and morphological identity: axial versus lateral patterning in the vertebrate mesoderm.

The successful organization of the vertebrate body requires that local information in the embryo be translated into a functional, global pattern. Somite cells form the bulk of the musculoskeletal system. Heterotopic transplants of segmental plate along the axis from quail to chick were performed to test the correlation between autonomous morphological patterning and Hox gene expression in somite subpopulations. The data presented strengthen the correlation of Hox gene expression with axial specification and focus on the significance of Hox genes in specific derivatives of the somites. We have defined two anatomical compartments of the body based on the embryonic origin of the cells making up contributing structures: the dorsal compartment, formed from purely somitic cell populations; and the ventral compartment comprising cells from somites and lateral plate. The boundary between these anatomical compartments is termed the somitic frontier. Somitic tissue transplanted between axial levels retains both original Hox expression and morphological identity in the dorsal compartment. In contrast, migrating lateral somitic cells crossing the somitic frontier do not maintain donor Hox expression but apparently adopt the Hox expression of the lateral plate and participate in the morphology appropriate to the host level. Dorsal and ventral compartments, as defined here, have relevance for experimental manipulations that influence somite cell behavior. The correlation of Hox expression profiles and patterning behavior of cells in these two compartments supports the hypothesis of independent Hox codes in paraxial and lateral plate mesoderm.

Manganese flux from continental margin sediments in a transect through the oxygen minimum.

The flux of manganese from continental margin sediments to the ocean was measured with a free-vehicle, benthic flux chamber in a transect across the continental shelf and upper slope of the California margin. The highest fluxes were observed on the shallow continental shelf. Manganese flux decreased linearly with bottom water oxygen concentration, and the lowest fluxes occurred in the oxygen minimum zone (at a depth of 600 to 1000 meters). Although the flux of manganese from continental shelf sediments can account for the elevated concentrations observed in shallow, coastal waters, the flux from sediments that intersect the oxygen minimum cannot produce the subsurface concentration maximum of dissolved manganese that is observed in the Pacific Ocean.