[Per-oral endoscopic myotomy for esophageal achalasia following distal gastrectomy].

The patient was a male in his 70s with a history of distal gastrectomy and Billroth-I reconstruction. He was suspected of having esophageal achalasia and was started on calcium blockers in X-2 year. The symptoms worsened, and he presented to our hospital in X year. We diagnosed esophageal achalasia (Chicago classification ver. 3.0;type I), and conducted per-oral endoscopic myotomy (POEM). His postoperative course was uneventful with no postoperative symptoms. In cases of esophageal achalasia following distal gastrectomy, it is important to consider adhesions, mobility of the remaining stomach, and preservation of the short gastric artery and vein. Since the Heller-Dor operation can be difficult, POEM may be a reasonable alternative in these cases.

[Emergency incompatible red cell transfusion to a patient whose blood type was suspended from identification].

We report a case of a 59-year-old woman who presented with hypovolemic shock and compensated acidosis (preoperative arterial blood gases: pH 7.3, P(CO2) 31.9 mmHg, Pa(O2) 112.3 mmHg, base excess -9.8, Hb 6.4 g x dl(-1)) due to perforated descending colon, necessitating emergency surgery. Tracheal intubation had been performed preoperatively. Prior to induction of anesthesia, blood pressure was 106/74 mmHg, heart rate 119 beats x min(-1), and Sp(O2) 100% breathing room air. Anesthesia was induced with remifentanil influsion at a rate of 0.05 mg x kg(-1) x min(-1), sevoflurane 1% and rocuronium bromide 30mg, and was maintained with oxygen, air, remifentanil and sevoflurane. For a critical hypovolemia, in accordance to the guidelines for intraoperative critical hemorrhage and the Japanese practical guidelines for blood components therapy, we started to transfuse incompatible red cell (O+) since the identification of blood typing was suspended. The duration of surgery was 104 min, with an intraoperative total bleeding of 125 ml. Four units of total blood transfusion and 3,050 ml of infusion of Ringer's acetate solution were administered. The patient was transferred to ICU with tracheal intubation. No adverse reactions associated with blood type incompatibility were recognized.

Masticatory motion is controlled in humans by a limited set of muscle synergies.

The masticatory motion, whereby food introduced into the mouth is processed into a bolus suitable for swallowing, can be divided into successive masticatory cycles, each comprising downward and subsequent upward movements of the mandible. The present study deals with the problem of the existence of muscle synergies in mastication, that is whether some of the muscles involved in mastication receive common motor drives, rather than controlled individually. Evidence for muscle synergy during mastication is scarce, partly due to the difficulties in simultaneous recording of the electromyographic (EMG) activities from all the muscles involved. Thus, we analyzed the variability of the mandibular motion during mastication rather than to examine the EMG patterns, based on the hypothesis that a motion elicited by a limited set of muscle synergies can be approximated as a superposition of the same number of independent motions. Mandibular motion paths were recorded from 8 healthy males (25-31 years), who chewed gum or gummy candy. A morphometric technique, which describes the shape of a closed curve by using normalized elliptic Fourier descriptors and reduces the variance of the shape by using principal component analysis, was applied to analyze the variability of the mandibular motion paths. We found three independent variations of the motion paths, whose linear combinations accounted for an average of 93% (range, 88-96%) of the total variance. The extracted variations were similar among the subjects. These findings provide indirect evidence for the existence of a limited set of muscle synergies for mastication in humans.

Bite forces and their resultants during forceful intercuspal clenching in humans.

We aimed to develop a method of gathering complete information on the system of bite forces acting on the dental arches during clenching with the teeth in maximum intercuspation. Further, we attempted to reduce this system into an equivalent wrench--a force-couple system comprising a single force and a single couple acting along a unique line of action. We investigated the normative distribution of the bite forces and the location and orientation of their resultant wrench in 30 young adults (18-23 yr) with natural dentitions. The number of detected occlusal contacts varied from 12 to 46 (mean: 26.1; SD: 8.4), and was significantly greater for the molars than the premolar and anterior teeth, as were the bite-force magnitudes at individual occlusal contacts (1.2-218.4 N); those resulted in the antero-posteriorly slanted bite-force distribution. The magnitude of the bite-force resultants varied from 246.9 to 2091.9 N, and the points at which the resultant wrench axes intersected the mandibular occlusal plane were located 21.3-37.6mm posterior to the incisal point and less than 8.9 mm from the midline bilaterally. The bite-force resultant was slightly inclined anteriorly from the perpendicular direction to the mandibular occlusal plane. Our method of using pressure-sensitive films to obtain information on all parameters needed to mechanically define a force (such as magnitude, direction, and point of application) is novel. To our knowledge, this is the first study investigating the system of bite forces during forceful intercuspal clenching in six degrees-of-freedom.