Paraduodenal hernia with situs inversus abdominalis: A case report.

INTRODUCTION & IMPORTANCE: Situs Inversus Abdominalis (SIA) & Paraduodenal Hernias (PDH) are extremely rare causes acute surgical emergencies among adults. We present a case of an adult patient with intestinal obstruction secondary to PDH through the fossa of Landzert with concurrent SIA. PRESENTATION OF CASE: A thirteen-year-old Southeast Asian female with situs inversus abdominalis due to Kartagener syndrome presented with bowel obstruction. The patient failed conservative management and required surgical intervention. A diagnostic laparoscopy was done followed by laparotomy. Intraoperatively, there was a paraduodenal mesentery defect at the duodenojejunal junction with internal herniation of the terminal ileum and caecum. Successful reduction of bowels and closure of the mesentery defect was done without any bowel resection. DISCUSSION: Only three cases of bowel obstruction secondary to SIA have been documented in literature. This is the fourth and the only case to have concurrent paraduodenal hernia. Surgical repair of PDH is mandatory to avoid the increased risk of incarceration or strangulation however pre-operative diagnosis of PDH resembles a diagnostic challenge especially among patients with intestinal anomalies. CONCLUSION: Intestinal malrotation is known to be the most common cause of intestinal obstruction in patients with intestinal anomalies. However, clinicians should maintain a high index of suspicion of intestinal herniation and adhesions as the cause of intestinal obstruction in such cases. Further imaging such as computed tomography (CT) scan and diagnostic laparoscopy may be beneficial provided patients have no overt signs of acute bowel ischaemia.

Novel coronavirus 2019 (COVID-19): Emergence and implications for emergency care.

A novel coronavirus (COVID-19) causing acute illness with severe symptoms has been isolated in Wuhan, Hubei Province, China. Since its emergence, cases have been found worldwide, reminiscent of severe acute respiratory syndrome and Middle East respiratory syndrome outbreaks over the past 2 decades. Current understanding of this epidemic remains limited due to its rapid development and available data. While occurrence outside mainland China remains low, the likelihood of increasing cases globally continues to rise. Given this potential, it is imperative that emergency clinicians understand the preliminary data behind the dynamics of this disease, recognize possible presentations of patients, and understand proposed treatment modalities.

Controlled activation of morphogenesis to generate a functional human microvasculature in a synthetic matrix.

Understanding the role of the extracellular matrix (ECM) in vascular morphogenesis has been possible using natural ECMs as in vitro models to study the underlying molecular mechanisms. However, little is known about vascular morphogenesis in synthetic matrices where properties can be tuned toward both the basic understanding of tubulogenesis in modular environments and as a clinically relevant alternative to natural materials for regenerative medicine. We investigated synthetic, tunable hyaluronic acid (HA) hydrogels and determined both the adhesion and degradation parameters that enable human endothelial colony-forming cells (ECFCs) to form efficient vascular networks. Entrapped ECFCs underwent tubulogenesis dependent on the cellular interactions with the HA hydrogel during each stage of vascular morphogenesis. Vacuole and lumen formed through integrins α(5)ß(1) and α(V)ß(3), while branching and sprouting were enabled by HA hydrogel degradation. Vascular networks formed within HA hydrogels containing ECFCs anastomosed with the host's circulation and supported blood flow in the hydrogel after transplantation. Collectively, we show that the signaling pathways of vascular morphogenesis of ECFCs can be precisely regulated in a synthetic matrix, resulting in a functional microvasculature useful for the study of 3-dimensional vascular biology and toward a range of vascular disorders and approaches in tissue regeneration.

Vascular endothelial growth factor and substrate mechanics regulate in vitro tubulogenesis of endothelial progenitor cells.

Endothelial progenitor cells (EPCs) in the circulatory system have been suggested to maintain vascular homeostasis and contribute to adult vascular regeneration and repair. These processes require that EPCs break down the extracellular matrix (ECM), migrate, differentiate and undergo tube morphogenesis. Evidently, the ECM plays a critical role by providing biochemical and biophysical cues that regulate cellular behaviour. Using a chemically and mechanically tunable hydrogel to study tube morphogenesis in vitro, we show that vascular endothelial growth factor (VEGF) and substrate mechanics co-regulate tubulogenesis of EPCs. High levels of VEGF are required to initiate tube morphogenesis and activate matrix metalloproteinases (MMPs), which enable EPC migration. Under these conditions, the elasticity of the substrate affects the progression of tube morphogenesis. With decreases in substrate stiffness, we observe decreased MMP expression while increased cellular elongation, with intracellular vacuole extension and coalescence to open lumen compartments. RNAi studies demonstrate that membrane type 1-MMP (MT1-MMP) is required to enable the movement of EPCs on the matrix and that EPCs sense matrix stiffness through signalling cascades leading to the activation of the RhoGTPase Cdc42. Collectively, these results suggest that coupled responses for VEGF stimulation and modulation of substrate stiffness are required to regulate tube morphogenesis of EPCs.