Search

To examine the effect of chronically elevated CO2 on excitability and function of neurons, we exposed mice to 8% and 12% CO2 for 4 weeks (starting at 2 days of age), and examined the properties of freshly dissociated hippocampal neurons obtained from slices. Chronic CO2-treated neurons (CC) had a similar input resistance (Rm) and resting membrane potential (Vm) as control (CON). While treatment with 8% CO2 did not change the rheobase (64±11 pA, n=9 vs. 47±12 pA, n=8 for CC 8% vs. CON), 12% CO2 treatment increased it significantly (73±8 pA, n=9, p=0.05). Furthermore, the 12% CO2 but not the 8% CO2 treatment decreased the Na+ channel current density (244±36 pA/pF, n=17, vs. 436±56 pA/pF, n=18, for CC vs. CON, p=0.005). Recovery from inactivation was also lowered by 12% but not 8% CO2. Other gating properties of Na+ current, such as voltage-conductance curve, steady state inactivation, and time constant for deactivation, were not modified by either treatment. Western blot analysis showed that the expression of Na+ channel types I, II and III was not changed by 8% CO2 treatment but their expression was significantly decreased by 20-30% (p=0.03) by the 12% treatment. We conclude from these data and others (Gu et al. 2004) that 1) neuronal excitability and Na+ channel expression depend on the duration and level of CO2 exposure and 2) maturational changes occur in early life regarding neuronal responsiveness to CO2. [ABSTRACT FROM AUTHOR]

Composite hydrogels have gained great attention as three-dimensional (3D) printing biomaterials because of their enhanced intrinsic mechanical strength and bioactivity compared to pure hydrogels. In most conventional printing methods for composite hydrogels, particles are preloaded in ink before printing, which often reduces the printability of composite ink with little mechanical improvement due to poor particle-hydrogel interaction of physical mixing. In contrast, the in situ incorporation of nanoparticles into a hydrogel during 3D printing achieves uniform distribution of particles with remarkable mechanical reinforcement, while precursors dissolved in inks do not influence the printing process. Herein, we introduced a "printing in liquid" technique coupled with a hybridization process, which allows 3D freeform printing of nanoparticle-reinforced composite hydrogels. A viscoplastic matrix for this printing system provides not only support for printed hydrogel filaments but also chemical reactants to induce various reactions in printed objects for in situ modification. Nanocomposite hydrogel scaffolds were successfully fabricated through this 3D freeform printing of hyaluronic acid (HAc)-alginate (Alg) hydrogel inks through a two-step crosslinking strategy. The first ionic crosslinking of Alg provided structural stability during printing, while the secondary crosslinking of photo-curable HAc improved the mechanical and physiological stability of the nanocomposite hydrogels. For in situ precipitation during 3D printing, phosphate ions were dissolved in the hydrogel ink and calcium ions were added to the viscoplastic matrix. The composite hydrogels demonstrated a significant improvement in mechanical strength, biostability, as well as biological performance compared to pure HAc. Moreover, the multi-material printing of composites with different calcium phosphate contents was achieved by adjusting the ionic concentration of inks. Our method greatly accelerates the 3D printing of various functional or hybridized materials with complex geometries through the design and modification of printing materials coupled with in situ post-printing functionalization and hybridization in reactive viscoplastic matrices., Competing Interests: No conflicts of interest were reported by all authors. This research was supported by Nanyang Technological University Start up grant, and A*STAR Advanced Manufacturing and Engineering Individual Research Grants grant A1983c0031 from A*STAR., (Copyright: © 2020 Chen, et al.)

Objective: To established a procedure for laparoscopic extraperitoneal ostomy after abdomino-perineal resection (APR) and study safety aspects and complications., Method: From July 2011 to July 2012, 36 patients with low rectal cancer undergoing APR were included in the study and divided into extraperitoneal ostomy group (n = 18) and intraperitoneal ostomy group (n = 18). Short- and long-term complications were compared between the two groups. All patients were followed up and the median duration was 17 months (range: 12-24)., Results: The rates of short-term complication related to colostomies were comparable between the two groups, except the rate for stoma edema was higher in the extraperitoneal group (33.3% vs 0%; P = 0.008). In the intraperitoneal ostomy group, two patients developed stoma prolapse, one had stoma stenosis, and two had parastomal hernia. In contrast, no long-term complications related to colostomies occurred in the extraperitoneal ostomy group. The rate of long-term complication was lower in the extraperitoneal ostomy group (0% vs 22.2%; P = 0.036)., Conclusion: The laparoscopic extraperitoneal ostomy is a relatively simple and safe procedure, with fewer long-term complications related to colostomy. However the follow-up period was not too long and needs to be extended.