Tensile test of pressureless-sintered silicon nitride at elevated temperature

Uniaxial tensile strength tests of pressureless sintered silicon nitride were carried out in air at temperatures ranging from room temperature up to 1600 C. Silicon nitrides containing Y2O3, Al2O3, Al2O3-MgO, or MgO-CeO2 additives were tested. The results show that the composition of the additive used influences the strength characteristics of the silicon nitride. The tensile strength rapidly decreased at temperatures above 1000 C for the materials containing MgO as the additive and above 1000 C for the material with Y2O3. When the temperature increased to as high as 1300 C, the strength decreased to about 10 percent of the room temperature strength in each case. Observations of the fracture origin and of the crack propagation on the fracture surfaces are discussed

Strength evaluation test of pressureless-sintered silicon nitride at room temperature

In order to study strength characteristics at room temperature and the strength evaluating method of ceramic materials, the following tests were conducted on pressureless sintered silicon nitride specimens: bending tests, the three tensile tests of rectangular plates, holed plates, and notched plates, and spin tests of centrally holed disks. The relationship between the mean strength of specimens and the effective volume of specimens are examined using Weibull's theory. The effect of surface grinding on the strength of specimens is discussed

成体マウス脳の成熟および未成熟オリゴデンドロサイトにおけるコルチコイステロイドレセプタ−の分布

The expression of glucocorticoid receptors (GRs) was investigated immunohistochemically in two different lineages of oligodendrocytes, using carbonic anhydrase (CA) II and neuron glial antigen (NG) 2 as markers of mature oligodendrocytes and oligodendrocyte progenitors, respectively. We focused on the gray matter regions, including CA1, CA3 and the dentate gyrus of the hippocampus, the primary somatosensory cortex barrel field and the basolateral amygdala, and the white matter regions, including the corpus callosum, external capsule and fimbria of the hippocampus. More than 80% of CAII-immunoreactive (IR) cells and more than 95% of NG2-IR cells expressed GRs in various regions of the brain. In contrast, neither CAII-IR cells nor NG2-IR cells expressed mineralocorticoid receptors (MRs) in the same regions. The intensity of GR expression was drastically reduced in CA II-IR cells and NG2-IR cells in the same regions in adrenalectomized mice. Finally, steroid receptor co-activator (SRC)-1 and p300, both of which are cofactors for GR, were expressed in the gray and white matter regions in NG2-IR cells, but not in CAII-IR cells. These results suggest that the expression of GRs in oligodendrocytes and their progenitor cells mediates several functions in vivo, including differentiation and myelination, as a major target of glucocorticoids and their cofactors.博士（医学）・甲620号・平成26年3月17日Copyright © 2014 by The Histochemical Societ

MRI multiparametric scoring system for pial blood supply of intracranial meningiomas

Background: Meningiomas are occasionally fed by pial blood supply (PBS). It is postulated that peritumoral flow void (PTFV), peritumoral brain edema (PTBE), and absence of an arachnoid plane (AP) are useful parameters for evaluating PBS. Purpose: To determine whether conventional magnetic resonance imaging (MRI) using a multiparametric scoring system (MSS) is a useful way to predict PBS. Material and Methods: Forty-six patients were included and divided: PBS and non-PBS groups. Differences between the groups in six parameters of MR imaging were analyzed: tumor size, tumor location, PTBE grade, AP grade, PTFV, and MIB1 labeling index (MIB1-LI) grade. Cutoff values were determined using receiver operating characteristic (ROC) curve analysis for the differentiation of both groups based on statistically significant parameters. All cases were scored as 1 (PBS) or 0 (non-PBS) for each parameter according to set thresholds. Individual scores were totaled for each case, yielding a combined score for each case to obtain a cutoff value using ROC curve analysis for the MSS. Results: Peritumoral brain edema grade, AP grade, PTFV, and MIB-LI grade were statistically associated with PBS. Receiver operating characteristic curve analyses showed that PTBE grade 3 or 4, AP grade 3 or 4, and PTFV positivity had the highest accuracy of 69%, 64%, and 68%, respectively. Regarding the MSS, a cutoff value of 2 had the highest accuracy of 71%; PBS diagnosis was indicated by at least two of the three parameters, namely, PTBE grade, AP grade, and PTFV. Conclusion: The MSS is a useful way to predict PBS in intracranial meningiomas on MRI

A Dilated Odontoma in the Second Molar Region of the Mandible

A case of dilated odontoma in the second molar region of the mandible was reported. The patient was a 14-year-old female. Panoramic X-ray and CT examination revealed an oval ring-shaped radiopaque lesion accompanying a radiolucent area in the center at the left second molar region of the mandible. The left second molar and all third molars were not found. The lesion was diagnosed as odontoma and extirpated under general anesthesia. The lesion was a spherical mass of 12x9mm. Histologically, the mass was composed of dentin arranged in an oval ring shape with dentinal tubules. Inside the dentin, immature enamel was present. The central area of the mass was filled with fibrous tissue with a small nest of bone and cementum. Bone tissue was also observed in contact with the immature enamel layer. These morphological and histological features are compatible with those of a dilated odontoma

High Signal Intensity of the Cochlear Modiolus on Unenhanced T1-Weighted Images in Classical Infratentorial Superficial Siderosis

Background: Superficial siderosis (SS) results from chronic bleeding in the subarachnoid space. SS can be classified as infratentorial SS (i-SS) and supratentorial SS (s-SS). The cochlear modiolus (CM) normally shows low signal intensity (SI) on Tl-weighted images (T1WI). We noticed persistently high SI of the CM on unenhanced thin-sliced T1WI in patients with i-SS. The purpose of this study was to evaluate the correlation between SS and high SI of the CM on unenhanced T1WI. Methods: This retrospective study analyzed three cases with i-SS, eight cases with s-SS, and 23 normal controls (NC) evaluated on unenhanced thin-sliced T1WI with a three-dimensional spoiled gradient-recalled echo sequence. CM-T1SI scores of 0, 1, and 2 indicated low, iso, and high SI, respectively. In cases with scores of 2 evaluated several times, all scores were reviewed for each case. The CM-T1SI ratio was defined as the contrast ratio between the CM and the cerebellum. Differences between the three groups were statistically analyzed based on the CM-T1SI score and ratio. Receiver operative curve (ROC) analysis was used to determine the cut-off values for differentiating the i-SS group from the NC group based on the CM-T1SI ratio. Results: Two patients with i-SS had a score of 2 on all evaluations. The CM-T1SI score and ratio differed significantly between the i-SS and NC groups. The accuracy of the CM-T1SI ratio for discriminating i-SS from NC was 98.9% at a cutoff value of 0.628. Conclusion: High SI of the CM on unenhanced TIWI can be an additional characteristic finding of i-SS

Comparison of recovery of mobility and self-efficacy after total knee arthroplasty based on two different protocols: A prospective cohort study

Objectives: The purpose of this study was to compare the recovery of mobility and self-efficacy following total knee arthroplasty (TKA) between the 5-day and the 28-day protocol. This prospective cohort study was carried out at two hospitals. Methods: In total, 104 patients who underwent TKA were enrolled. The primary outcomes measured were Life Space Assessment (LSA) for mobility and modified-Gait Efficacy Scale (mGES) for self-efficacy. Knee Society Score (KSS) was used to estimate the functional outcomes. These assessments were performed in all patients preoperatively, and at 1, 3, and 6 months postoperatively. After calculating the propensity score using covariates, such as patient characteristics, LSA, mGES, and KSS at baseline, propensity score-adjusted multivariate analysis of covariance (MANCOVA) was performed. Results: MANCOVA revealed significant differences in LSA and mGES, but not in KSS, between the two protocols. The adjusted means of LSA and mGES in the 28-day protocol were significantly greater than those in the 5-day protocol in all the postoperative assessments. Conclusion: Mobility and self-efficacy were greater following the 28-day protocol than the 5-day protocol after TKA. Our findings suggest that the modified treatment procedure for improving mobility and self-efficacy is necessary to introduce the early discharge protocol in Japan