Time to Catheter Angiography for Gastrointestinal Bleeding after Prior Positive Investigation Does Not Affect Bleed Identification.

OBJECTIVE: To determine, time to angiography for patients with positive gastrointestinal bleeding (GIB) on prior investigation (endoscopy [ES], nuclear medicine [NM] Tc99m red blood cells (RBC) scan, or computed tomography angiography), affects angiographic bleed identification. MATERIALS AND METHODS: Visceral Angiograms performed from January 2012 to August 2017 were evaluated. Initial angiograms performed for GIB were included in the study. Exclusion criteria included recent abdominal surgery or procedure (30 days), empiric embolization (embolization without visualized active bleeding), and use of vasodilators, or subsequent angiogram. Timing and results of ES, NM Tc99m RBC scan, or computed tomography angiogram and catheter angiogram were recorded. In addition, age, gender, angiogram time, anti- platelet therapy, anti-coagulation therapy, bleed location, international normalized ratio, and units of packed RBCs received in the 24 h before catheter angiography were included in the study. RESULTS: One hundred and seventy angiograms were included in the final analysis. Forty-three angiograms resulted in the identification of an active bleed (68.9 years, and 67.4% male). All of these patients were embolized successfully. One hundred and twenty-seven angiograms failed to identify an active bleed (70.4 years, and 49.6% male). No significance was found across the two groups with respect to time from prior positive investigation. Receiver operating characteristic analysis demonstrated that units of packed RBCs received in the preceding 24 h were correlated with positive bleed identification on catheter angiography. CONCLUSION: Time to angiography from prior positive investigation, including ES, NM Tc99m RBC scan, or computed tomography angiogram does not correlate with positive angiographic outcomes. Increasing units of packed RBCs administered in the 24 h before angiogram do correlate with positive angiographic findings.

Collective cancer cell invasion induced by coordinated contractile stresses.

The physical underpinnings of fibrosarcoma cell dissemination from a tumor in a surrounding collagen-rich matrix are poorly understood. Here we show that a tumor spheroid embedded in a 3D collagen matrix exerts large contractile forces on the matrix before invasion. Cell invasion is accompanied by complex spatially and temporally dependent patterns of cell migration within and at the surface of the spheroids that are fundamentally different from migratory patterns of individual fibrosarcoma cells homogeneously distributed in the same type of matrix. Cells display a continuous transition from a round morphology at the spheroid core, to highly aligned elongated morphology at the spheroid periphery, which depends on both ß1-integrin-based cell-matrix adhesion and myosin II/ROCK-based cell contractility. This isotropic-to-anisotropic transition corresponds to a shift in migration, from a slow and unpolarized movement at the core, to a fast, polarized and persistent one at the periphery. Our results also show that the ensuing collective invasion of fibrosarcoma cells is induced by anisotropic contractile stresses exerted on the surrounding matrix.