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Yuichi Kasai,1 Takaya Kato,2 Tadashi Inaba,3 Sotaro Baba,3 Permsak Paholpak,1 Taweechok Wisanuyotin,1 Weerachai Kosuwon,1 Hirohito Hirata,4 Tadatsugu Morimoto4 1Department of Orthopaedics, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand; 2Graduate School of Regional Innovation Studies, Tsu, Japan; 3Department of Mechanical Engineering, Graduate School of Engineering, Mie University, Tsu, Japan; 4Department of Orthopedic Surgery, Faculty of Medicine, Saga University, Saga, JapanCorrespondence: Yuichi Kasai, Email ykasai55@gmail.comIntroduction: Although kissing spine syndrome in the lumbar spinal region is a relatively common condition in older adults, no study examining its biomechanical characteristics has been reported. We hypothesized that kissing of the spinous processes during extension causes an increase in the flexural rigidity of the spine and significantly limits the deformation behavior of extension, which in turn might cause lower back pain.Methods: Three test models (human cadavers A, B, and C) were prepared by removing supraspinal/interspinous ligaments between L4 and L5. The dental resin was attached to the cephalocaudal spinous process so that the spinous processes between L4 and L5 were almost in contact with each other to simulate the condition of a kissing spine. The flexion-extension direction’s torque–range-of-motion (torque–ROM) curve was generated with a six-axis material tester for biomechanical measurements.Results: In all three models, the maximum ROMs at the time of extension were smaller than those at the time of flexion, and no sudden increase in torque was observed during extension.Conclusion: The results indicated no apparent biomechanical effects of kissing between the spinous processes, suggesting that the contact between the spinous processes has little involvement in the onset of lower back pain.Keywords: kissing spine syndrome, Baastrup’s disease, biomechanical study, low back pain, lumbar spine

Naoki Aoyama, Masashi Izumi, Toru Morimoto, Hiroyuki Wada, Junpei Dan, Yusuke Kasai, Yoshinori Satake, Koji Aso, Masahiko Ikeuchi Department of Orthopedic Surgery, Kochi Medical School, Kochi University, Nankoku, JapanCorrespondence: Masashi Izumi, Department of Orthopedic Surgery, Kochi Medical School, Kochi University, 185-1 Oko-cho Kohasu, Nankoku, 783-8505, Japan, Tel +81-88-880-2386, Fax +81-88-880-2388, Email izumim@kochi-u.ac.jpPurpose: The mechanisms underlying chronic postsurgical pain after joint replacement (JR) are complex, and it has been suggested that chronic postsurgical pain can develop as a result of inadequate acute pain management. Few studies have addressed acute pain after JR using specific animal models. This study aimed to develop a novel JR model focused on postsurgical pain assessment and the time course of pain recovery.Materials and Methods: Rats were allocated to the following three groups: sham (joint exposure), joint destruction (JD; resection of the femoral head), and JR (femoral head replacement using an originally developed implant). The time course of postsurgical pain behavior was measured using a dynamic weight-bearing apparatus, along with radiological assessments. The expression of calcitonin gene-related peptide-immunoreactive (CGRP-IR) neurons in the dorsal root ganglion (DRG) was evaluated by immunohistochemistry on days 28 and 42.Results: The ratio of weight-bearing distribution in the JR group gradually recovered from day 14 and reached the same level as that in the sham group on day 42, which was significantly greater than that in the JD group after day 7 (p< 0.05). Radiologically, no significant issues were found, except for transient central migration of the implant in the JR group. The percentage of CGRP-IR DRG neurons in the JR group was significantly lower than that in the JD group on day 28 (mean, 37.4 vs 58.1%, p< 0.05) and day 42 (mean, 32.3 vs 50.0%, p< 0.05).Conclusion: Our novel JR model presented acute postsurgical pain behavior that was successfully recovered to the baseline level at day 42 after surgery. Difference of the pain manifestation between the JR and JD groups could be supported by the expression of CGRP-IR in DRG neurons. This model is the first step toward understanding detailed mechanisms of post-JR pain.Keywords: joint replacement, postsurgical pain, dynamic weight bearing, CGRP

Yusuke Kasai, Koji Aso, Masashi Izumi, Hiroyuki Wada, Junpei Dan, Yoshinori Satake, Toru Morimoto, Masahiko Ikeuchi Department of Orthopedic Surgery, Kochi Medical School, Kochi University, Nankoku, 783-8505, JapanCorrespondence: Koji AsoDepartment of Orthopedic Surgery, Kochi Medical School, Kochi University, 185-1 Oko-cho Kohasu, Nankoku, 783-8505, JapanTel +81-88-880-2386Fax +81-88-880-2388Email koji.aso@gmail.comPurpose: Nonunion bone fracture can be a cause of persistent pain, but the pathophysiology remains largely unknown. The objective of this study was to identify how nonunion affect persistent pain after fracture. Specifically, we evaluated the association of neuropeptide change in dorsal root ganglia (DRG) and nerve proliferation at fracture sites with pain.Methods: Rat union and nonunion fracture models were created. A piece of latex glove was placed at the fracture site to create a nonunion model. At 6 weeks after surgery, bone healing was assessed using radiography. In addition, the presence of calcitonin gene-related peptide-immunoreactive (CGRP-IR) DRG at the level of L3 and anti-growth associated protein 43-immunoreactive (GAP43-IR) nerve fibers in the scar tissue between the bone fragments were evaluated. Pain-related behavior was assessed using forced treadmill running.Results: In radiological images at 6 weeks after surgery, callus formation was formed continuously between bone fragments in the union models. On the one hand, a clear gap was detected between fragments in nonunion models. The percentage of CGRP-IR DRG cells and the density of GAP43-IR nerve fibers in the scar tissue between the bone fragments in nonunion models was significantly higher than that in union models (p < 0.05). An increase in inflammatory cell infiltrate was observed in scar tissues in the nonunion models. During forced treadmill running, rats in the union model could run significantly longer than those in the nonunion models.Conclusion: Increased CGRP expression in DRG cells and abnormal nerve proliferation secondary to prolonged inflammation could lead to persistent pain after bone fracture. In clinical practice, early achievement of bone union may minimize the development of persistent pain after fractures.Keywords: fracture pain, nerve proliferation, nonunion of fractures

Toshihiko Sakakibara, Zhuo Wang, Yuichi KasaiDepartment of Spinal Surgery and Medical Engineering, Mie University Graduate School of Medicine, Tsu City, Mie Prefecture, JapanBackground: Low back pain is often called nonspecific pain. In this type of low back pain, various emotions and stress are known to strongly affect pain perception. The purpose of this study is to investigate how the degree of low back pain changes in people with chronic mild low back pain when they are inside and outside of an amusement park where people are supposed to have physical and psychological enjoyment.Methods: The subjects were 23 volunteers (13 males and 10 females) aged 18 to 46 years old with a mean age of 24.0 years who had chronic low back pain. Visual analog scale (VAS) scores of low back pain and salivary amylase levels (kIU/L) of all subjects were measured at five time points: immediately after getting on the bus heading for the amusement park; 10 minutes, 1 hour (immediately after boarding the roller coaster), and 3 hours (immediately after exiting the haunted house) after arriving at the amusement park; and immediately before getting off the bus returning from the park.Results: The three VAS values in the amusement park (10 minutes, 1 hour, and 3 hours after arriving at the amusement park) measured were significantly lower (P < 0.05) when compared with the other two values measured immediately after getting on the bus heading for the amusement park and immediately before getting off the return bus. In salivary amylase levels, there were no statistically significant differences among the values measured at the five time points.Conclusion: Low back pain was significantly alleviated when the subjects were in the amusement park, which demonstrated that enjoyable activities, though temporarily, alleviated their low back pain.Keywords: low back pain, emotion, salivary alpha-amylase activity, enjoyment activities, psychological stress

We present a chromatic deflection aberration-free beam-image-shifting technique for low-voltage scanning electron microscopy. The technique utilizes a Wien filter to correct the chromatic deflection aberration induced by the beam-image shift. Experimental results demonstrated that this method significantly improves spatial resolution across a large field of view (FOV) of 28 × 28 μm2, covered by the beam-image shift. By correcting the chromatic deflection aberration, the degradation rate of the spatial resolution at the corner of the FOV relative to its center reduced from a maximum of 16% to 8%. The developed Wien filter responded 60% faster than the beam-image shift, eliminating the need for additional settling time for correction. Furthermore, we applied the presented technique to semiconductor pattern measurement and showed significant potential to improve the critical dimension uniformity in the FOV covered by the beam-image shift. We believe that the proposed method provides a practical and cost-effective amelioration as a beam-image-shifting technique. [ABSTRACT FROM AUTHOR]

Since stereotactic radiotherapy (SRT) for large brain metastases (BMs) is known to be associated with a higher risk of brain necrosis (BN), different fractionation protocols depending on tumor size are often employed. However, dosimetric predictors of the normal brain have not been clarified yet in fractionated SRT. Patients (pts) who were treated by fractionated SRT protocols were analyzed. Following pts were excluded in this study: 1) previous surgery or radiotherapy history; 2) meningitis carcinomatosa; 3) melanoma, hematologic malignancy, and small cell lung cancer; 4) WHO performance status of 3–4; 6) BM number > 10. In the first protocol employed from 2012 to 2016, the basic prescribed dose was 35 Gy/5 fr. For small lesions (maximum diameter < 1.5 cm), 30 Gy/3 fr was permitted. For large lesions (≥ 3 cm), 37.5 Gy/5 fr was used. From 2017 to 2021, the protocol for the large BMs was revised to decrease the incidence of BN. For large lesions (≥ 15 cc), treatment with 35 Gy or 37.5 Gy/5 fr was superseded by 40 Gy/10 fr. These pts were followed once every ≤ 3 months with physical examinations and contrast-enhanced MRI. BN was pathologically verified or diagnosed by functional MRI findings. To explore dosimetric predictors of BN, the dose-volume data of the normal organs and targets were extracted from the radiation planning systems. The biological equivalent doses to the brain with an α/β ratio of 2 Gy were calculated using the linear quadratic model to assess different fractionation schedules. Multivariate logistic regression models were developed to explore BN predictors. In total, 112 pts (median age 68 years) with 215 BMs were treated according to these protocols. Among them, 76 pts had lung cancers and 106 had extracranial lesions. The 3-fraction (-fr) treatment was delivered to 34 pts with 74 BMs, the 5-fr treatment to 58 with 106 BMs, and the 10-fr treatment to 20 with 35 BMs. Mean target volumes in the 3-, 5- and 10-fr groups were 4.3, 15.4, and 25.9 cc, respectively (P < 0.001). The overall survival rate at 1 year was 54% (median, 13 months). One-year local tumor control rates were 92% in the 3-fr group, 94% in the 5-fr group, and 82% in the 10-fr group (P = 0.11). BN of grade (G) 2 or higher occurred in 4 pts in the 3-fr, 7 in the 5-fr, and 0 in the 10-fr groups. BNs (≥ G1) were observed in 7 in the 3-fr, 9 in the 5-fr, and 1 in the 10-fr groups. In the 5- or 10-fr groups, BNs were more frequently observed in pts with a larger brain volume receiving 55 Gy biologically equivalent dose in 2 Gy fractions (V55GyE). The odds ratios of ≥ G1 and ≥ G2 BNs were 1.06 ((95% confidence interval: 1.01-1.12, P < 0.03) and 1.06 (1.01-1.12, P < 0.02), respectively. G2 BNs occurred in 3% (V55GyE ≤ 15 cc), 8% (> 15 cc, ≤ 30 cc), and 22 % (> 30 cc). In the 3-fr group, no risk predictor was identified. BrainV55GyE emerges as a significant dosimetric predictor for BN in cases treated with 5- or 10-fr SRT. [ABSTRACT FROM AUTHOR]

Research describing the response of intrinsic Josephson junctions to far infrared radiation is presented. The effect on impedance matching of increasing the number of junctions in the resistive state is investigated.