136 research outputs found
Perioperative outcome of laparoscopic left lateral liver resection is improved by using a bioabsorbable staple line reinforcement material in a porcine model
Hypothesis Laparoscopic liver surgery is significantly limited by the technical difficulty encountered during transection of substantial liver parenchyma, with intraoperative bleeding and bile leaks. This study tested whether the use of a bioabsorble staple line reinforcement material would improve outcome during stapled laparoscopic left lateral liver resection in a porcine model. Study design A total of 20 female pigs underwent stapled laparoscopic left lateral liver resection. In group A (n = 10), the stapling devices were buttressed with a bioabsorbable staple line reinforcement material. In group B (n = 10), standard laparoscopic staplers were used. Operative data and perioperative complications were recorded. Necropsy studies and histopathological analysis were performed at 6 weeks. Data were compared between groups with the Student's t-test or the chi-square test. Results Operating time was similar in the two groups (64 +/- 11 min in group A versus 68 +/- 9 min in group B, p = ns). Intraoperative blood loss was significantly higher in group B (185 +/- 9 mL versus 25 +/- 5 mL, p <0.05). There was no mortality. There was no morbidity in the 6-week follow-up period; however, two animals in group B had subphrenic bilomas (20%) at necropsy. At necropsy, methylene blue injection via the main bile duct revealed leakage from the biliary tree in four animals in group B and none in group A (p <0.05). Histopathological examination of the resection site revealed minor abnormalities in group A while animals in group B demonstrated marked fibrotic changes and damaged vascular and biliary endothelium. Conclusion Use of a bioabsorbable staple line reinforcement material reduces intraoperative bleeding and perioperative bile leaks during stapled laparoscopic left lateral liver resection in a porcine model
Non-specific binding of Na and Mg to RNA determined by force spectroscopy methods
RNA duplex stability depends strongly on ionic conditions, and inside cells
RNAs are exposed to both monovalent and multivalent ions. Despite recent
advances, we do not have general methods to quantitatively account for the
effects of monovalent and multivalent ions on RNA stability, and the
thermodynamic parameters for secondary structure prediction have only been
derived at 1M [Na]. Here, by mechanically unfolding and folding a 20 bp RNA
hairpin using optical tweezers, we study the RNA thermodynamics and kinetics at
different monovalent and mixed monovalent/Mg salt conditions. We measure
the unfolding and folding rupture forces and apply Kramers theory to extract
accurate information about the hairpin free energy landscape under tension at a
wide range of ionic conditions. We obtain non-specific corrections for the free
energy of formation of the RNA hairpin and measure how the distance of the
transition state to the folded state changes with force and ionic strength. We
experimentally validate the Tightly Bound Ion model and obtain values for the
persistence length of ssRNA. Finally, we test the approximate rule by which the
non-specific binding affinity of divalent cations at a given concentration is
equivalent to that of monovalent cations taken at 100 fold that concentration
for small molecular constructs.Comment: main paper (32 pages, 11 figures, 1 table) + supplementary
information (15 pages
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