Electrochemical investigation of formic acid electro-oxidation and its crossover through a Nafion® membrane

This work studies formic acid as an anode fuel for polymer electrolyte fuel cells and investigates the electro-oxidation of formic acid on Pt/C. Fuel crossovers through the Nafion^® 115 membrane at different temperatures and concentrations are reported. A linear dependence of the crossover current on the temperature and concentration is obtained. It is found that the crossover can be reduced by five times and a higher performance can be rendered by formic acid when compared to methanol under the same conditions. Electrochemical impedance measurements are conducted to interpret the reaction mechanism of formic acid oxidation. The effect of the electrode potential on the impedance pattern is revealed and an impedance model incorporating the reaction kinetics information is developed to simulate the experimental impedance response.     

A microfluidic device mimicking acinar concentration gradients across the liver acinus

The acinus-mimicking microfluidic chip, which simulates the in vivo condition of the liver, was developed and reported in this paper. The gradient microenvironment of the liver acinus is replicated within this proposed microfluidic chip. The advantage of this acinus-mimicking chip is capable of adjusting the concentration gradient in a relatively short period of time at around 10 s. At the same instance the non-linear concentration gradient can be presented in the various zones within this microfluidic chip. The other advantage of this proposed design is in the convenience of allowing the direct injection of the cells into the chip. The environment within the chip is multi-welled and gel-free with high cell density. The multi-row pillar microstructure located at the entrance of the top and bottom flow channels is designed to be able to balance the pressure of the perfusion medium. Through this mechanism the shear stress experienced by the cultured cells can be minimized to reduce the potential damage flow from the perfusion process. ⁽³⁾The fluorescence staining and the observations of the cell morphology verify the life and death of the cells. The shear stress experienced by the cells in the various zones within the chip can be effectively mapped. The serum glutamic oxaloacetic transaminase (SGOT) collected from the supernatants was used to determine the effects of the degassing process and the shear stress of the medium flow on the cultured cells.     

Treatment-influenced associations of PML-RARα mutations, FLT3 mutations, and additional chromosome abnormalities in relapsed acute promyelocytic leukemia

Mutations in the all-trans retinoic acid (ATRA)-targeted ligand binding domain of PML-RARα (PRα/LBD(+)) have been implicated in the passive selection of ATRA-resistant acute promyelocytic leukemia clones leading to disease relapse. Among 45 relapse patients from the ATRA/chemotherapy arm of intergroup protocol C9710, 18 patients harbored PRα/LBD(+) (40%), 7 of whom (39%) relapsed Off-ATRA selection pressure, suggesting a possible active role of PRα/LBD(+). Of 41 relapse patients coanalyzed, 15 (37%) had FMS-related tyrosine kinase 3 internal tandem duplication mutations (FLT3-ITD(+)), which were differentially associated with PRα/LBD(+) depending on ATRA treatment status at relapse: positively, On-ATRA; negatively, Off-ATRA. Thirteen of 21 patients (62%) had additional chromosome abnormalities (ACAs); all coanalyzed PRα/LBD mutant patients who relapsed off-ATRA (n = 5) had associated ACA. After relapse Off-ATRA, ACA and FLT3-ITD(+) were negatively associated and were oppositely associated with presenting white blood count and PML-RARα type: ACA, low, L-isoform; FLT3-ITD(+), high, S-isoform. These exploratory results suggest that differing PRα/LBD(+) activities may interact with FLT3-ITD(+) or ACA, that FLT3-ITD(+) and ACA are associated with different intrinsic disease progression pathways manifest at relapse Off-ATRA, and that these different pathways may be short-circuited by ATRA-selectable defects at relapse On-ATRA. ACA and certain PRα/LBD(+) were also associated with reduced postrelapse survival.     

Gasless laparoscopic assisted surgery for abdominal trauma

Background

Numerous studies have described the effectiveness of laparoscopy for trauma patients. In gas-filling laparoscopic surgery, most of the disadvantages are related to a positive pressure pneumoperitoneum that compromises the cardiopulmonary function. The main advantage of gasless laparoscopic assisted surgery (GLA) is that it does not affect the haemodynamic status, which is particularly critical for trauma patients. The purpose of this study was to investigate the feasibility and safety of GLA for abdominal trauma.

Materials and methods

This was a retrospective, 1:2 matched case–control study of all trauma gasless assisted laparoscopies performed from January 2010 until January 2013 in a Level I trauma centre. In total, 965 patients with abdominal trauma were admitted. According to the abdominal trauma protocol, a total of 93 hemodynamically stable patients required the operation; we selected fifteen patients to undergo GLA and matched 30 other patients to undergo laparotomy. Demographic information, perioperative findings, injury severity score, and postoperative recovery were recorded and analyzed.

Results

A total of fifteen patients (ten men, five women) with a mean age of 44.4, standard deviation (SD) 13.2 years underwent GLA for abdominal trauma. Eight patients had penetrating injuries, while seven had blunt injuries. Overall, 73% patients had multiple injuries. The mean time to the identified lesion was 23.1, SD 10.9 min, and the mean operative time was 109.7, SD 33.5 min. Most of the lesions were repaired concurrently by GLA. One conversion to laparotomy was done. The mean length of hospital stay (HLOS) was 9.1, SD 4.5 days. No mortality occurred in this series. The mean follow-up was 22.0, SD 7.9 months, and there were no significant events during this period. The mean operative times were comparable in the GLA and open surgery group (109.7, SD 33.5 vs. 131.2, SD 43.6 min; p = 0.076). Compared with the open surgery group, the HLOS was significantly shorter in the GLA group (9.1, SD 4.5 vs.16.3, SD 6.4 days; p = 0.030).

Conclusion

GLA offers both therapeutic and diagnostic advantages for patients with abdominal trauma. GLA shares the advantages of laparoscopy and prevents the cardiopulmonary function from being compromised due to pneumoperitoneum, which is especially critical for trauma patients.     

Significance of the mass-compression effect of postlaminectomy/laminotomy fibrosis on histological changes on the dura mater and nerve root of the cauda equina: an experimental study in rats

Purpose The precise mechanism and pathological role of postlaminectomy/laminotomy fibrosis (PLF) in postoperative neurological deficits have not been established. Many studies use magnetic resonance imaging (MRI) to prove that there is no consistent correlation between PLF and postoperative neurological deficits and back pain (PNDBP). Therefore, we assumed that the direct-compression effect may not be the only factor but that other neurological deficits associated with pathological mechanisms should exist and need more investigation. The purpose of this study was to compare over time the differences and changes in histopathological properties of PLF in rats.Methods We used a rat model with walking-track analysis for neurologic evaluation, grading scale to evaluate PLF, histomorphometric measurements of dura sac diameter, and histological tissue reactions (dura mater and spinal rootlets) juxtaposed to the postlaminectomy/laminotomy defect. The 54 adult Sprague–Dawley rats were divided into laminotomy (n = 18), laminectomy (n = 18), and sham-operation groups (n = 18). All groups were subdivided into three equal subgroups based on different postoperative time points (1, 2, and 3 months). All sections of vertebral column were stained with hematoxylin and eosin and with Masson’s trichrome.Results The results showed that only a slight compression effect reflected by nonsignificant changes in the maximum anterior-posterior diameters within the dura sac, in the walking tract test, and increased grades of PLF over time. In addition, significant pathological inflammatory changes, such as thickening of the dura mater, axonal swelling, and neovascularization, were found in the post-laminectomy/laminotomy groups at each time point.Conclusion Laminectomy-/laminotomy-related inflammation may lead to PLF, and these pathological changes may be the main cause of postoperative neurological deficits. These findings show that research on preventing PLF should include perioperative modulation of inflammatory reactions induced by laminectomy/laminotomy.     

Surgeon Elective Abdominal Aortic Aneurysm Repair Volume and Outcomes of Ruptured Abdominal Aortic Aneurysm Repair: A 12-year Nationwide Study

Background

The purpose of the present study was to examine the effects of surgeon elective abdominal aortic aneurysm repair volume on outcomes after ruptured abdominal aortic aneurysm (rAAA) repair.

Methods

A nationwide claims database was used to identify patients who underwent rAAA repair from 1998 to 2009. Surgeon elective open abdominal aortic aneurysm repair (EAR) volume was classified as low, medium, or high. Associations between surgeon EAR volume and in-hospital mortality, overall survival, and complications after open rAAA repair (RAR) were compared with multivariate analysis. Associations between surgeon elective endovascular abdominal aortic aneurysm repair (EER) volume and outcomes after endovascular rAAA repair (RER) were also analyzed.

Results

A total of 537 patients who underwent rAAA repair were identified, including 498 who underwent RAR and 39 who underwent RER. In-hospital mortality rates after RAR were 49, 38, and 24 % in the low, medium, and high EAR volume groups, respectively (p < 0.001). Patients in the low surgeon EAR volume group had higher in-hospital mortality than those in the high surgeon EAR volume group [odds ratio 3.39, 95 % confidence interval (CI) 1.52, 7.59; p = 0.003]. Patients in the low surgeon EAR volume group also had higher long-term mortality (hazard ratio 1.86, 95 % CI 1.21, 2.85; p = 0.005). There were no significant differences in complication rates among the surgeon EAR volume groups or in-hospital mortality after RER among the surgeon EER volume groups.

Conclusions

Surgeon EAR volume is associated with in-hospital mortality and long-term survival after RAR.