Dorsoventral Patterning in Hemichordates: Insights into Early Chordate Evolution

We have compared the dorsoventral development of hemichordates and chordates to deduce the organization of their common ancestor, and hence to identify the evolutionary modifications of the chordate body axis after the lineages split. In the hemichordate embryo, genes encoding bone morphogenetic proteins (Bmp) 2/4 and 5/8, as well as several genes for modulators of Bmp activity, are expressed in a thin stripe of ectoderm on one midline, historically called “dorsal.” On the opposite midline, the genes encoding Chordin and Anti-dorsalizing morphogenetic protein (Admp) are expressed. Thus, we find a Bmp-Chordin developmental axis preceding and underlying the anatomical dorsoventral axis of hemichordates, adding to the evidence from Drosophila and chordates that this axis may be at least as ancient as the first bilateral animals. Numerous genes encoding transcription factors and signaling ligands are expressed in the three germ layers of hemichordate embryos in distinct dorsoventral domains, such as pox neuro, pituitary homeobox, distalless, and tbx2/3 on the Bmp side and netrin, mnx, mox, and single-minded on the Chordin-Admp side. When we expose the embryo to excess Bmp protein, or when we deplete endogenous Bmp by small interfering RNA injections, these expression domains expand or contract, reflecting their activation or repression by Bmp, and the embryos develop as dorsalized or ventralized limit forms. Dorsoventral patterning is independent of anterior/posterior patterning, as in Drosophila but not chordates. Unlike both chordates and Drosophila, neural gene expression in hemichordates is not repressed by high Bmp levels, consistent with their development of a diffuse rather than centralized nervous system. We suggest that the common ancestor of hemichordates and chordates did not use its Bmp-Chordin axis to segregate epidermal and neural ectoderm but to pattern many other dorsoventral aspects of the germ layers, including neural cell fates within a diffuse nervous system. Accordingly, centralization was added in the chordate line by neural-epidermal segregation, mediated by the pre-existing Bmp-Chordin axis. Finally, since hemichordates develop the mouth on the non-Bmp side, like arthropods but opposite to chordates, the mouth and Bmp-Chordin axis may have rearranged in the chordate line, one relative to the other

Left renal vein transposition for posterior Nutcracker syndrome

Nutcracker syndrome (NCS) is a rare cause of pelvic venous congestion syndrome and is secondary to either compression of the left renal vein in its normal anatomic position by the superior mesenteric artery and aorta or less commonly when the left renal vein is in a retroaortic position, compressed between the aorta and the spine. We herein present a unique case of NCS in a female patient with a history of chronic pelvic pain and venous congestion. We also review the literature and discuss the diagnostic modalities, differential diagnosis, and various open surgical and endovascular options for NCS

Outcomes of Adult Venovenous Extracorporeal Membrane Oxygenation Patients without Anticoagulation: A Retrospective Review at a Tertiary Level Referral Center.

Introduction Extracorporeal membrane oxygenation (ECMO) provides cardiopulmonary support for patients with acute respiratory and/or cardiac failure. Patients are therapeutically anticoagulated with heparin to prevent thrombi from forming in the extensive conduit, centrifugal pump, or oxygenator-circuit systems. Heparin use is interrupted if life threatening bleeding develops. We examined outcomes for adult patients on venovenous ECMO who had their heparin interrupted compared with those who did not. Methods A single institution retrospective study was performed for adult patients on venovenous ECMO from 2013 to 2015. Patients whose heparin was interrupted for ≥24 hours were compared with those with uninterrupted heparin use. Results There were 64 patients, 34 of whom had at least 1 heparin interruption meeting the criteria. Patients in the interruption group had significantly longer duration of ECMO (19.4 vs 8.8 days, p=0.001), developed more deep vein thrombosis (DVT) (35.3% vs 13.3%, p=0.043), and had an increased mortality rate (47.1% vs 23.3%, p=0.049). The rate of deaths per day on ECMO was almost identical between the 2 groups (0.024 vs 0.026). No death was attributable to thromboembolism; the majority of deaths were due to worsening multiorgan system failure (Table)

Outcomes Comparison for Microsurgical Breast Reconstruction in Specialty Surgery Hospitals Versus Tertiary Care Facilities

Background:. Postoperative monitoring is crucial in the care of free flap breast reconstruction patients. Tertiary care facilities (TCFs) provide postoperative monitoring in an ICU after surgery. Specialty surgery hospitals (SSHs) do not have ICUs, but these facilities perform free flap breast reconstruction as well. Are outcomes comparable between the 2 facilities in terms of flap reexploration times and overall success? Methods:. Retrospective study including 163 SSH and 157 TCF patients. Primary predictor was facility in which the procedure was performed. Secondary predictors included operative, demographic, and comorbidity data. Primary outcomes were flap take back rate and flap failures. Secondary outcomes were total time from adverse event noticed in the flap to returning to the operating room (OR) and total time from decision made to return to the OR to returning to the OR (decision made). Tertiary outcomes were length of stay, operative times, and blood loss. Results:. Patients at the TCF were generally less healthy than SSH patients. Salvage rates and failure rates were similar between the 2 institutions. Adverse event noticed and decision made times did not differ between the 2 facilities. Overall flap success rate was 98.22% at SSH and 98.81% at TCF. No primary or secondary predictors had a significant correlation with increased odds for flap failure. Conclusion:. SSHs can offer similar outcomes in free flap breast reconstruction with just as effective clinical response times to endangered flaps as found in a TCF. However, surgery at an SSH may best be reserved for healthier patients

Crisis to Collapse

This volume comprises the proceedings of a workshop with the same title which took place in October 2015. It was organised within the frame of the ARC13/18-049 (concerted research action) ‘A World in Crisis?’. It has both a large chronological scope-from the Late Paleolithic to the 12th c. AD - and wide geographical coverage, with case studies from the Maya, Southern US, Aegean, Sri Lanka, Indus, Gaul, Southern Levant, Anatolia, Egypt, North-western Europe, Alaska and Mesopotamia. It discusses and critically analyses the variety of signatures and archaeological correlates of crisis conditions that led to social breakdown. As such it makes massive strides forward to a better theoretical understanding of crisis-induced collapse