悪性食道狭窄に対する金属ステント療法

Self-expandable metallic stents were used for palliative treatment of malignant esophagogastric strictures. Twelve patients, nine men and three women, with a mean age of 73.1 years old (range, 48-87 years old) had dysphagia due to esophagogastric strictures with advanced malignant tumors. A total of 13 expandable metallic stents were placed, four non-covered Ultraflex stents (nitinol stents), two non-covered Wallstents and seven covered Wallstents. The strictures were caused by esophageal carcinoma (n=7), gastric carcinoma with lymphnode metastasis (n=2), lung carcinoma with mediastinal lymphnode metastasis (n=2), and cardioesophageal carcinoma (n=1). All stents were placed with fluoroscopic and endoscopic guidance. No technical failure or procedural critical complications occurred and the dysphagia was relieved in all patients. The mean dysphagia score was 0.58±0.52 (standard deviation) before treatment and 3.25±0.97 after insertion. Complications included chest and epigastric pain in four, gastroesophageal reflux in two, tumor ingrowth in one, and food impaction in one. Six complications easily managed with medical, endoscopic, or radiologic intervention. At the end of this study, eight patients were dead with a mean survival of 28.3 weeks (range, 4-96 weeks), and four patients were alive with a mean follow up of 35.5 weeks (range, 8-98 weeks). In our experience, self-expandable metallic stents provide relatively safe and long-term palliation in patients with malignant esophagogastric obstruction

A biomechanical investigation of mandibular molar implants: reproducibility and validity of a finite element analysis model

Background: Three-dimensional finite element analysis (FEA) is effective in analyzing stress distributions around dental implants. However, FEA of living tissue involves many conditions, and the structures and behaviors are complex; thus, it is difficult to ensure the validity of the results. To verify reproducibility and validity, we embedded implants in experimental models and constructed FEA models; implant displacements were compared under various loading conditions. Methods: Implants were embedded in the molar regions of artificial mandibles to fabricate three experimental models. A titanium superstructure was fabricated and three loading points (buccal, central, and lingual) were placed on a first molar. A vertical load of 100 N was applied to each loading point and implant displacements were measured. Next, the experimental models were scanned on micro computed tomography (CT) and three-dimensional FEA software was used to construct two model types. A model where a contact condition was assumed for the implant and artificial mandible (a contact model) was constructed, as was a model where a fixation condition was assumed (a fixation model). The FEA models were analyzed under similar conditions as the experimental models; implant displacements under loading conditions were compared between the experimental and FEA models. Reproducibility of the models was assessed using the coefficient of variation (CV), and validity was assessed using a correlation coefficient.Results: The CV of implant displacement was 5–10% in the experimental and FEA models under loading conditions. Absolute values of implant displacement under loading were smaller in FEA models than the experimental model, but the displacement tendency at each loading site was similar. The correlation coefficient between the experimental and contact models for implant displacement under loading was 0.925 (p < 0.01). The CVs of equivalent stress values in the FEA models were 0.52–45.99%.Conclusions: Three-dimensional FEA models were reflective of experimental model displacements and produced highly valid results. Three-dimensional FEA is effective for investigating the behavioral tendencies of implants under loading conditions. However, the validity of the absolute values was low and the reproducibility of the equivalent stresses was inferior; thus, the results should be interpreted with caution

Chondroitin sulfate N-acetylgalactosaminyltransferase-1 is required for normal cartilage development

CS (chondroitin sulfate) is a glycosaminoglycan species that is widely distributed in the extracellular matrix. To understand the physiological roles of enzymes involved in CS synthesis, we produced CSGalNAcT1 (CS N-acetylgalactosaminyltransferase 1)-null mice. CS production was reduced by approximately half in CSGalNAcT1-null mice, and the amount of short-chain CS was also reduced. Moreover, the cartilage of the null mice was significantly smaller than that of wild-type mice. Additionally, type-II collagen fibres in developing cartilage were abnormally aggregated and disarranged in the homozygous mutant mice. These results suggest that CSGalNAcT1 is required for normal CS production in developing cartilage

Cryogenic deuterium target experiments with the GEKKO XII, green laser system

Copyright 1995 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Physics of Plasmas, 2(6), 2495-2503, 1995 and may be found at http://dx.doi.org/10.1063/1.87121

On the origin and evolution of the asteroid Ryugu: A comprehensive geochemical perspective

Presented here are the observations and interpretations from a comprehensive analysis of 16 representative particles returned from the C-type asteroid Ryugu by the Hayabusa2 mission. On average Ryugu particles consist of 50% phyllosilicate matrix, 41% porosity and 9% minor phases, including organic matter. The abundances of 70 elements from the particles are in close agreement with those of CI chondrites. Bulk Ryugu particles show higher δ18O, Δ17O, and ε54Cr values than CI chondrites. As such, Ryugu sampled the most primitive and least-thermally processed protosolar nebula reservoirs. Such a finding is consistent with multi-scale H-C-N isotopic compositions that are compatible with an origin for Ryugu organic matter within both the protosolar nebula and the interstellar medium. The analytical data obtained here, suggests that complex soluble organic matter formed during aqueous alteration on the Ryugu progenitor planetesimal (several 10’s of km), <2.6 Myr after CAI formation. Subsequently, the Ryugu progenitor planetesimal was fragmented and evolved into the current asteroid Ryugu through sublimation