No abstract

Abstract:Robots that reside inside the body to restore or enhance biological function have long been a staple of science fiction. Creating such robotic implants poses challenges both in signaling between the implant and the biological host as well as in implant design. To investigate these challenges, we created a robotic implant to perform in vivo tissue regeneration via mechano-stimulation. The robot is designed to induce lengthening of tubular organs, such as the esophagus and intestines, by computer-controlled application of traction forces. Esophageal testing in swine demonstrates that the applied forces can induce cell proliferation and lengthening of the organ without a reduction in diameter, while the animal is awake, mobile and able to eat normally. Such robots can serve as research tools for studying mechanotransduction-based signaling and can also be employed clinically for conditions such as long-gap esophageal atresia and short bowel syndrome. One Sentence Summary:We have created a robotic implant for inducing tissue growth in tubular organs and demonstrated its potential through esophageal lengthening in swine.

Key words: hydrostatic pressure/Schizosaccharomyces pombe/microtubn\Qs/microfila.mQnts/^uorQscQncQmicroscopy/ immunoelectron microscopy ABSTRACT. The effects of hydrostatic pressure on ultrastructure, microtubules and micro filaments of Schizosaccharomyces pombewere investigated by fluorescence microscopy, conventional electron microscopy and immunoelectron microscopy. Cells were treated with hydrostatic pressure from 0.1 to 400 MPafor 10 min at room temperature. The nuclear membranewas disrupted at above 100 MPa. At 150 MPathe matrixes of mitochondria had an electron dense area. At 250 MPathe cytoplasmic substances changed dramatically, the cellular organelles could hardly be detected and the fragmented nuclear membrane was barely visible. The fluorescence in a-tubulin was lost in most of the cells at 100 MPa. The gold particles for anti a-tubulin were not visible in the cells at the same level. Cell cycle specific actin distribution was lost even at 50 MPa, although actin dots localized at the central region remained unchanged. Thick actin cables appeared at 100 MPa. Complete depolymerization of F-actin was observed at 150 MPa. These results suggest that S. pombecells were more sensitive than Saccharomycescerevisiae cells. The damageto microtubules and nuclear membranecaused by hydrostatic pressure was thought to be followed by breakdown of nuclear division apparatus and the inhibition of nuclear division. This damage might contribute to the frequent formation of polyploidy in S. pombe.Our previous investigations by conventional electron microscopyrelated to hydrostatic pressure effects on the budding yeast Saccharomyces cerevisiae (16) and the dimorphic yeast Candida tropicalis (14, 15) revealed that the membranesystems, especially the nuclear membrane were most susceptible to pressure stress even at 100 MPa.An electron dense matrix appeared in the organelles and cytoplasm above 200 MPa. Under fluorescence microscopycell cycle specific organization of microfilaments and microtubules was altered whenS. cerevisiae and both yeast and hyphal form cells in C. tropicalis were exposed to hydrostatic pressure stress at 100-150 MPa. Hyphal cells were found to be more sensitive to pressure treatment than yeast form cells and microtubules to be more sensitive than micro filaments (14). It was also demonstrated that hydrostatic pressure of 200 to 250 MPa greatly inactivated S. cerevisiae cells while inducing polyploidy at a high frequency of 15% (6).Immunoelectron microscopy (immuno EM) using ultrathin frozen sectioning (9) in S. cerevisiae revealed deposits of gold particles for anti a-tubulin in the nucleus at 150 MPa, although no filamentous structure of microtubules was recognized. The damageto microtubules and nuclear membranecaused by such stress was thought to be followed by a breakdown of nuclear division apparatus and the inhibition of nuclear division. Onozato confirmed that the breakdown of the mitotic spindle after application of hydrostatic pressure induced the formation of polyploidy in salmonid eggs (13).W...

Aorto-oesophageal fistula (AEF) is a rare but life-threatening disease with an underlying infective aetiology that can cause serious complications. This study investigated the clinical outcomes of patients with AEF who received in situ cryopreserved aortic allograft replacement. From August 2000 to February 2011, 11 patients with AEF received aortic allografts; 5 for primary AEF caused by ruptured aortic aneurysm and 6 for secondary AEF that comprised 4 cases following thoracic endovascular aortic repair (TEVAR) and 2 after open graft replacement of the thoracic aorta. As for results, 2 cases of primary AEF received TEVAR and then allograft replacement, one for graft infection and the other for bleeding. Three primary AEF cases received allografts directly. Six secondary AEF cases received staged (5) or simultaneous (1) oesophagectomy and allograft replacement. There were 3 in-hospital deaths (27%), 2 because of bleeding and one because of multisystem organ failure. Four patients completed oesophageal reconstruction. There were 2 late deaths, one due to aspiration pneumonia and one of unknown cause. In conclusion, surgical results for repair of AEF using cryopreserved aortic allograft were satisfactory considering preoperative critical condition, and this type of allograft appears to be an ideal graft of choice.