The Frequency of Mediastinal Injury in Acute Posterior Sternoclavicular Dislocations: A Multicenter Study.

BACKGROUND: Acute posterior sternoclavicular dislocations (APSCD) are rare injuries that historically have prompted concern for injury to the great vessels and other mediastinal structures from initial trauma or subsequent treatment, resulting in the recommendation that a thoracic or vascular surgeon be present or available during operative treatment. The objectives of the study were to characterize the demographic, clinical, and radiographic characteristics of a large series of APSCDs in skeletally immature patients and to describe the rate and nature of any vascular or mediastinal complications that occurred during treatment. METHODS: Following Institutional Review Board approval, records of consecutive patients under 25 years of age treated for APSCD were collected from each of 6 participating centers. Only acute injuries (sustained fewer than 10 days before presentation) were included. Patient demographics, injury mechanism, associated mediastinal injuries, and need for thoracic/vascular surgery were recorded. Mediastinal structures injured or compressed by mass effect were specifically characterized by review of preoperative computed tomography imaging. RESULTS: Review identified 125 patients with a mean age of 14.7 years; 88% were male. APSCD most commonly resulted from a sporting injury (74%) followed by falls from standing height (10%) and high-energy motor vehicle trauma (10%). The most common finding on cross-sectional imaging was compression without laceration of the ipsilateral brachiocephalic vein (50%). Eleven patients had successful closed reduction, and 114 (90%) had open reduction and internal fixation, with 25 failed or unstable closed reductions preceding open treatment. There were no vascular or mediastinal injuries during reduction or fixation that required intervention. CONCLUSIONS: In this multicenter series of 125 APSCDs no injuries to the great vessels/mediastinal structures requiring intervention were identified. Although more than half of patients had evidence of extrinsic vascular compression at the time of injury, careful open reduction of acute injuries can be safely performed. Although vascular injuries following APSCD seem to be quite rare, vascular complications can be catastrophic. Treating providers should consider these data and their own institutional resources to maximize patient safety during the treatment of APSCD. LEVEL OF EVIDENCE: Level III-therapeutic case control study.

Pollen on Stigmas of Herbarium Specimens: A Window into the Impacts of a Century of Environmental Disturbance on Pollen Transfer.

Pollination is necessary for plant reproduction but often highly susceptible to disruption, for example, by habitat fragmentation and climate change. Here, we indirectly evaluated on a century timescale pollination interactions for species in one of the historically most disturbed habitats on earth-tropical dry forests of Hawai'i. We employed a novel method for acquiring a historical perspective on temporal change in pollination by characterizing pollen on stigmas of herbarium specimens from six remnant native species collected from 1909-2002. We determine whether temporal shifts occurred in (1) pollination quantity and quality or (2) the composition of species interacting via pollen transfer. While pollen quantity remained constant, these remnant species interact with different species in modern times via pollen transfer than they did nearly 100 years ago. Species that are resilient to long-term environmental change may also be the ones subject to changes in pollination interactions.

Consequences of invasion for pollen transfer and pollination revealed in a tropical island ecosystem.

Pollination is known to be sensitive to environmental change but we lack direct estimates of how quantity and quality of pollen transferred between plant species shifts along disturbance gradients. This limits our understanding of how species compositional change impacts pollen receipt per species and structure of pollen transfer networks. We constructed pollen transfer networks along a plant invasion gradient in the Hawaiian dry tropical forest ecosystem. Flowers and stigmas were collected from both native and introduced plants, pollen was identified and enumerated and floral traits were measured. We also characterized pollen loads carried by individuals of the dominant invasive pollinator, Apis mellifera. Species flowering in native-dominated sites were more tightly connected by pollen transfer than those in heavily invaded sites. Compositional turnover in the pollen loads of A. mellifera was correlated (70%) with turnover in the composition of pollen transfer networks. Floral traits predicted species roles within pollen transfer networks, but many of these differed qualitatively depending on whether plants were native or introduced. Our work indicates that pollen transfer networks change with invasion. Floral morphology and foraging behaviour of the introduced super-generalist pollinator are implicated as key in determining the roles introduced species play within native pollen transfer networks.

Considering the unintentional consequences of pollinator gardens for urban native plants: is the road to extinction paved with good intentions?

Urban centers are important foci for plant biodiversity and yet widespread planting of wildflower gardens in cities to sustain pollinator biodiversity is on the rise, without full consideration of potential ecological consequences. The impact of intentional wildflower plantings on remnant native plant diversity in urban and peri-urban settings has not received attention, although shared pollinators are likely to mediate several types of biotic interactions between human-introduced plants and remnant native ones. Additionally, if wildflower species escape gardens these indirect effects may be compounded with direct ones. We review the potential positive and negative impacts of wildflower gardens on urban native flowering plants, and we reveal substantial gaps in our knowledge. We present a roadmap for research to address whether wildflower gardens, while benefiting pollinators, could also hasten the extinction of native remnant plants in urban settings, or whether they could have other effects that enrich urban biodiversity. Goals of future wildflower mixes should consider the totality of potential interactions.

Comparative mapping reveals autosomal origin of sex chromosome in octoploid Fragaria virginiana.

Recent evolution of separate sexes in flowering plants provides unparalleled opportunities for understanding the early stages of sex chromosome evolution, including their origin from autosomes. Moreover, the transition from combined to separate sexes can be associated with speciation via polyploidization in angiosperms, suggesting that genome doubling/merger may facilitate sterility mutations required for sex chromosome formation. To gain insight into the origin of sex chromosomes in a polyploid plant, we doubled the simple sequence repeat (SSR) density and increased genome coverage in a genetic map of octoploid Fragaria virginiana, a species purported to have a "proto-sex" chromosome, where limited recombination occurs between 2 linked "loci" carrying the male- and female-sterility mutations. Incorporation of almost 3 times the number of SSR markers into the current map facilitated complete characterization of the F. virginiana proto-sex chromosome, revealing its largely autosomal nature and the location of the sex-determining region toward the distal end. Furthermore, extensive synteny between our genetic map and a map involving diploid hermaphroditic congeners allowed assignment of linkage groups to homeologous groups, identification of the proto-sex chromosome's autosomal homoeolog, and detection of a putative rearrangement near the sex-determining region. Fine mapping and additional comparative work will shed light on the intriguing possibility that rearrangements during polyploidization were involved in the evolution of sex chromosomes in Fragaria.