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Waves in reaction-diffusion systems yield a wealth of dynamic self-assembling phenomena in nature. Recent studies have been devoted to utilizing these active waves in conjunction with microscale technology. To provide a compass for controlling reaction-diffusion waves in microspaces, we have investigated the propagation behavior of one specific variety of the reaction-diffusion wave: an acid wave that utilizes an autocatalytic proton-production reaction. Furthermore, the acid wave that we have investigated occurs in a microchannel with a junction connecting circular and straight regions. The obtained results were compared with a neutralization wave that involves only a neutralization reaction. The acid wave was ignited by the addition of the appropriate amount of H2SO4 into the circular region that was filled with a substrate solution, where proton-consuming and proton-producing reactions followed a rapid neutralization reaction. At this stage, the wave penetrated and propagated into the channel region. Comparison between the acid and the neutralization waves clarified that the acid wave required a minimum threshold of H2SO4 concentration in order to be ignited and that the propagation of the acid wave was temporarily delayed because of the presence of intermediate chemical reaction steps. Furthermore, the propagation dynamics was found to be tuned through the configuration of the microchannel. The importance of microchannel configuration, especially for systems with a junction connecting different shapes, is discussed in terms of Fick's law and in terms of the proton flux from the circular to the straight regions.

Objectives Treatments for unilateral vocal fold paralysis (UVFP) include conservative voice rehabilitation, vocal fold injection, and laryngeal framework surgery. We proposed basic fibroblast growth factor (bFGF) injection as a potential novel treatment for UVFP and have reported the short‐term results. In this study, we present the long‐term results and safety of vocal fold bFGF injection as a treatment for UVFP. Methods This retrospective study included 42 patients (25 males and 17 females) with UVFP who were administered a local injection of bFGF. The injection regimen involved injecting FGF (0.5 μg/ml in 0.5 ml per side) into the bilateral vocal folds using a 23‐gauge injection needle. Phonological outcomes were evaluated 6 months and 12 months after the injection. Results Overall, 26 patients received a single injection of bFGF, six patients received an additional injection, and 10 patients received the additional framework surgery. Maximum phonation time, mean flow rate, pitch range, jitter and shimmer percentages, the total GRBAS (grade, roughness, breathiness, asthenia, strain) score, and voice handicap index scores improved significantly in the long term. In patients who received the additional injection or framework surgery, the effects of bFGF injection were temporary, but did not interfere with the performance of the framework surgery. Conclusion In total, 42 patients who underwent vocal fold bFGF injections were reviewed. The bFGF injections were effective and safe in the long‐term results for UVFP in the selected cases. Some patients with severe symptoms benefited from the additional framework surgery but not the additional bFGF injection.

Pancreas divisum (PD) is a congenital anomaly in which the ventral and dorsal pancreatic ducts fails to fuse in the early fetal period. This anomaly has been known to rarely cause recurrent pancreatitis and to require surgical intervention. With the recent advances in image diagnostic procedures, an increasing incidence of this anomaly has been recognized in the pediatric age group. Seven cases of PD were encountered in our institution between 1978 and 1998. Six were female and one was male, with a mean age of 8 years. All cases were diagnosed to have PD by endoscopic retrograde pancreatography (ERCP) or operative pancreatography. One case (14.3%) had PD associated with a bout of pancreatitis and was operated on by transduodenal papilloplasty, but recurrent bouts of pancreatitis led to the performance of longitudinal pancreaticojejunostomy (Puestow procedure). Six cases (85.7%) were found to have PD as an incidental finding during operation for congenital dilatation of the bile ducts (CDBD), however, 2 cases (33.3%) out of the 6 developed pancreatitis in a later stage and ERCP was effective in their follow-up assessment. One benefited from conservative treatment while the other needed transduodenal papilloplasty along with pancreatoductoplasty. Imaging procedures (ERCP or operative pancreatography) revealed complete PD in 3 cases (42.9%), and incomplete PD in 4 cases (57.1%), however, there was no clinically significant difference between the groups.