Presenilin-2 Mutation Causes Early Amyloid Accumulation and Memory Impairment in a Transgenic Mouse Model of Alzheimer's Disease

In order to clarify the pathophysiological role of presenilin-2 (PS2) carrying the Volga German Kindred mutation (N141I) in a conventional mouse model of Alzheimer's disease (AD) expressing amyloid precursor protein (APP) with the Swedish mutation (Tg2576 line), we generated a double transgenic mouse (PS2Tg2576) by crossbreeding the PS2 mutant with Tg2576 mice. Here, we demonstrate that the PS2 mutation induced the early deposition of amyloid β-protein (Aβ) at 2-3 months of age and progressive accumulation at 4-5 months of age in the brains of the mutant mice. The PS2 mutation also accelerated learning and memory impairment associated with Aβ accumulation at 4-5 months of age in Tg2576 mice. These results suggest that the PS2 mutation causes early cerebral amyloid accumulation and memory dysfunction. PS2Tg2576 mice are a suitable mouse model for studying amyloid-lowering therapies

Pullout Strength of Pedicle Screws

Study Design: A cadaveric biomechanical study designed to test the pullout strength of pedicle screws. Objective: To evaluate the pullout strength of redirected pedicle screws with a larger diameter following lateral wall breach, redirected pedicle screws of the same diameter following medial wall breach, and redirected pedicle screws with a larger diameter following medial wall breach. Summary of Background Data: Screw malposition is one of the main pitfalls of inserting pedicle screws. Intraoperatively a malpositioned screw is re-directed and inserted along the correct axis. Methods: Forty-seven vertebrae (T9–L5) were harvested from 8 fresh cadaveric spines. The 18 pedicle screws that breached the lateral wall were then removed and redirected using a pedicle screw of 1 mm larger in diameter. The 16 pedicle screws that had breached the medial wall were then removed and redirected using a pedicle screw of the same diameter. The other 13 pedicle screws that had breached the medial wall were then removed and redirected using a pedicle screw of 1 mm larger in diameter. The pullout strength was measured. Results: Following lateral wall breach, mean pullout strength for the larger redirected screws was 46.9% greater than that of the correctly aligned screws. Following medial wall breach, mean pullout strength for the redirected screws of the same diameter was 20.6% less than that of the correctly aligned screws. Mean pullout strength for the larger pedicle screws following medial wall breach was 27.3% more than that of the correctly aligned screws. Conclusion: Redirected pedicle screws of larger diameter after a lateral or medial pedicle breach show recovery of pullout strength. However, the pullout strength of redirected pedicle screws of the same diameter after a medial pedicle breach is significantly less than that of correctly aligned screws.Redirected pedicle screws of larger diameter after a lateral or medial pedicle breach show the recovery of pullout strength. However, the pullout strength of redirected pedicle screws of the same diameter after a medial pedicle breach is significantly less than that of correctly aligned screws

骨形成シートによる顎顔面の再生 : ラットにおける実験研究

OBJECTIVE: Regeneration of maxillofacial bone defects, characterized by relatively small but complicated shapes, poses a significant clinical challenge. Osteogenic matrix cell sheets (OMCSs) have osteogenic ability and good shaping properties and may be ideal graft materials. Here, we assessed whether implantation of OMCSs could be used to repair maxillofacial bone defects. DESIGN: We adopted a rat mandibular symphysis model. The rat mandible is formed by a paired bone and the central portion consisting of fibrous tissue. There is no bone tissue at the site; accordingly, this site was interpreted as a physiological bone gap and was used for evaluation. Rat bone marrow cells were cultured in medium containing dexamethasone and ascorbic acid phosphate to create OMCSs. The OMCSs were implanted into the rat mandibular symphysis without a scaffold. Microcomputed tomography and histological analyses were conducted after 2, 4, and 8 weeks. RESULTS: Two weeks after implantation, microcomputed tomography images and histological sections showed some sparse granular calcification tissue within the bone gap at the mandibular symphysis. At 4 weeks, the calcification tissue spread, and the gap of the mandibles were continued. At 8 weeks, this continuous new bone tissue was matured. The experimental group showed abundant new bone tissue in the group with OMCS implantation, but not in the group with sham implantation. CONCLUSIONS: Our present results indicated that use of OMCSs may be an optimal approach towards achieving maxillofacial regeneration.博士（医学）・甲第668号・平成29年3月15日Copyright © 2016 Elsevier Ltd. All rights reserved

Debridement Using FED System for young children

Objective : Infectious spondylodiscitis (IS) is rarely seen in healthy elementary school age children. Conservative treatment with antibiotics is usually preferable but sometimes fails because of the low identification rate of the pathogen by percutaneous needle biopsy. When surgical treatment is indicated, selecting the appropriate procedure is crucial in terms of invasiveness for such young children. Case report : We present the case of a 9-year-old otherwise healthy girl with IS who successfully underwent debridement and identification of the causative pathogen using full endoscopic discectomy (FED) system. Methicillin-susceptible Staphylococcus aureus was identified on several cultures of samples. Immediately after the surgery, the LBP was significantly decreased and the remittent fever resolved dramatically. At the 1-year follow-up, she had no symptoms and plain radiographs showed bony fusion. Conclusion : This is the first report on IS in elementary school-age children treated with the FED system. Debridement using this system could provide minimally invasive and effective curettage of the infected disc space and can be helpful in identifying the pathogen even for small children

Accurate diagnosis of low back pain

Background : There is few reports evaluated accurately the pain generator of low back pain in elite athletes. The purpose of this report was to show case series and to investigate the cause of unidentified low back pain of elite athletes. Methods : Twenty-three adult elite athletes consulted our sports spine clinic to seek a second opinion for low back pain between April 2013 and March 2016. Their cause of low back pain had not been identified by nearby doctor. Spine surgeons had diagnosed using diagnostic injection and STIR-MRI and the final diagnosis made by the spine surgeon were collected. Results : The mean age of 23 patients (16 male, 7 female) was 30.4 years. The most common sport played was baseball. The final diagnosis made by a spine surgeon was as follows : disc related low back pain (n = 12), facet joint arthritis (n = 5), vertebral endplate injury (n = 4), early-stage lumbar spondylolysis (n = 1), supraspinous ligament injury (n = 1). Conclusions : A thorough medical interview, careful physical examination, appropriate diagnostic imaging, and injection block examination can effectively identify the cause of low back pain