Estimating urban spatial structure based on remote sensing data.

Understanding the spatial structure of a city is essential for formulating a spatial strategy for that city. In this study, we propose a method for analyzing the functional spatial structure of cities based on satellite remote sensing data. In this method, we first assume that urban functions consist of residential and central functions, and that these functions are measured by trip attraction by purpose. Next, we develop a model to explain trip attraction using remote sensing data, and estimate trip attraction on a grid basis. Using the estimated trip attraction, we created a contour tree to identify the spatial extent of the city and the hierarchical structure of the central functions of the city. As a result of applying this method to the Tokyo metropolitan area, we found that (1) our method reproduced 84% of urban areas and 94% of non-urban areas defined by the government, (2) our method extracted 848 urban centers, and their size distribution followed a Pareto distribution, and (3) the top-ranking urban centers were consistent with the districts defined in the master plans for the metropolitan area. Based on the results, we discussed the applicability of our method to urban structure analysis.

The muscle evoked potential after epidural electrical stimulation of the spinal cord as a monitor for the corticospinal tract: studies by collision technique and double train stimulation.

To study if spinal motor evoked potentials (SpMEPs), muscle responses after electrical stimulation of the spinal cord, can monitor the corticospinal tract. Study 1 comprised 10 consecutive cervical or thoracic myelopathic patients. We recorded three types of muscle responses intraoperatively: (1) transcranial motor evoked potentials (TcMEPs), (2) SpMEPs and (3) SpMEPs + TcMEPs from the abductor hallucis (AH) using train stimulation. Study 2 dealt with 5 patients, who underwent paired train stimulation to the spinal cord with intertrain interval of 50-60 ms for recording AH SpMEPs. We will also describe two illustrative cases to demonstrate the clinical value of AH SpMEPs for monitoring the motor pathway. In Study 1, SpMEPs and SpMEPs + TcMEPs recorded from AH measured nearly the same, suggesting the collision of the cranially evoked volleys with the antidromic signals induced by spinal cord stimulation via the corticospinal tracts. In Study 2, the first and second train stimuli elicited almost identical SpMEPs, indicating a quick return of transmission after 50-60 ms considered characteristic of the corticospinal tract rather than the dorsal column, which would have recovered much more slowly. Of the two patients presented, one had no post-operative neurological deteriorations as anticipated by stable SpMEPs, despite otherwise insufficient IONM, and the other developed post-operative motor deficits as predicted by simultaneous reduction of TcMEPs and SpMEPs in the face of normal SEPs. Electrical stimulation of the spinal cord primarily activates the corticospinal tract to mediate SpMEPs.

Intraoperative Spinal Cord Monitoring: Focusing on the Basic Knowledge of Orthopedic Spine Surgeon and Neurosurgeon as Members of a Team Performing Spine Surgery under Neuromonitoring.

An intraoperative functional spinal cord monitoring system is a technology used by spine and spinal cord surgeons to perform a safe surgery and to gain further surgical proficiency. However, no existing clinical neurophysiological method used in the operating room can monitor all complex spinal cord functions. Therefore, by observing the activities of certain neural action potentials transferred via limited neural tissues, surgeons need to deductively estimate the function of the whole spinal cord. Thus, as the number of spinal cord functions that need to be observed increases, spinal cord monitoring can be more reliable. However, in some situations, critical decision-making is affected by the limited capability of these methods. Nevertheless, good teamwork enables sharing of seamless information within the team composed of a surgeon, anesthesiologist, monitoring technician and nurses greatly contributes to making quick and accurate decisions. The surgeon, who is the person in charge of the team, should communicate with multidisciplinary team members using common technical terms. For this reason, spine and spinal cord surgeons must have appropriate knowledge of the methods currently used, especially of their utility and limitations. To date, at least six electrophysiological methods are available for clinical utilization: three are used to monitor sensory-related tracts, and three are used to monitor motor-related spinal cord functions. If surgeons perform electrode setting, utilizing their expertise, then the range of available methods is broadened, and more meticulous intraoperative functional spinal cord monitoring can be carried out. Furthermore, if the team members share information effectively by utilizing a clinically feasible judicious checklist or tools, then spinal cord monitoring will be more reliable.

Controlling CO2 emissions for each area in a region: the case of Japan.

BACKGROUND: Global warming is the most serious problem we face today. Each country is expected to ensure international cooperation toward minimizing risk. To evaluate the countermeasures, many researchers have developed integrated assessment models (IAMs). Then, how can each country achieve its emission quota? This study proposes models that analyze the economic impact of global warming in a region based on the results obtained by the global model. By using these suggested models, we perform a comparative analysis on three policy cases: a different regulations case, a unified regulation case, and an output redistribution case. RESULTS: We analyzed Japan as one of the case studies and found that more developed areas should implement stricter regulations in all scenarios. In addition, the case of applying different regulations by area (in a region) is not always preferable to using unified regulations in the region. Alternatively, the output gap between the output redistribution case and the different regulations case is much higher than the gap between the unified regulation case and the different regulations case. In all scenarios, the present values of the output of the output redistribution case are also higher than the other cases. CONCLUSIONS: The different regulations case and the unified regulation case are based on the model without capital transfer between areas, whereas the output redistribution case is based on the model with free capital transfer between areas. Although both models are extreme situations, the regions close to the without capital transfer situation possibly have an incentive to use the different regulations policy, depending on the emission target. The regions close to the situation with free capital transfer would probably prefer unified regulation.

Can postoperative deltoid weakness after cervical laminoplasty be prevented by using intraoperative neurophysiological monitoring?

Laminoplasty, frequently performed in patients with cervical myelopathy, is safe and provides relatively good results. However, motor palsy of the upper extremities, which occurs after decompression surgery for cervical myelopathy, often reduces muscle strength of the deltoid muscle, mainly in the C5 myotome. The aim of this study was to investigate prospectively whether postoperative deltoid weakness (DW) can be predicted by performing intraoperative neurophysiological monitoring (IONM) during cervical laminoplasty and to clarify whether it is possible to prevent palsy using IONM. We evaluated the 278 consecutive patients (175 males and 103 females) who underwent French-door cervical laminoplasty for cervical myelopathy under IONM between November 2008 and December 2016 at our hospital. IONM was performed using muscle evoked potential after electrical stimulation to the brain [Br(E)-MsEP] from the deltoid muscle. Seven patients (2.5%) developed DW after surgery (2 with acute and 5 with delayed onset). In all patients, deltoid muscle strength recovered to ≥ 4 on manual muscle testing 3-6 months after surgery. Persistent IONM alerts occurred in 2 patients with acute-onset DW. To predict the acute onset of DW, Br(E)-MsEP alerts in the deltoid muscle had both a sensitivity and specificity of 100%. The PPV of persistent Br(E)-MsEP alerts had both a sensitivity and specificity of 100% for acute-onset DW. There was no change in Br(E)-MsEP in patients with delayed-onset palsy. The incidence of deltoid palsy was relatively low. Persistent Br(E)-MsEP alerts of the deltoid muscle had a 100% sensitivity and specificity for predicting a postoperative acute deficit. IONM was unable to predict delayed-onset DW. In only 1 patient were we able to prevent postoperative DW by performing a foraminotomy.

Nodular gastritis in association with gastric cancer development before and after Helicobacter pylori eradication.

BACKGROUND AND AIM: Nodular gastritis is caused by Helicobacter pylori infection and is associated with the development of diffuse-type gastric cancer. This study examined the clinical characteristics of patients with nodular gastritis, including cancer incidence before and after H. pylori eradication. METHODS: This was a retrospective study of patients who underwent upper endoscopy and were positive for H. pylori infection. We examined the clinical findings and follow-up data after H. pylori eradication in patients with and without nodular gastritis. RESULTS: Of the 674 patients with H. pylori infections, nodular gastritis was observed in 114 (17%). It was more prevalent in women (69%) and young adults. Among patients with nodular gastritis, six (5%) had gastric cancer, all of which were of the diffuse type. Among the 19 (4%) patients with gastric cancer and no nodular gastritis, 16 had intestinal-type cancer. White spot aggregates in the corpus, a specific finding in patients with nodular gastritis, were more frequently observed in patients with gastric cancer than in those without (83% vs 26%, P = 0.0025). Of 82 patients with nodular gastritis who had H. pylori eradicated successfully, none developed gastric cancer over a 3-year follow-up period, while 7 (3%) of 220 patients without nodular gastritis developed gastric cancer after H. pylori eradication. CONCLUSIONS: In patients with nodular gastritis, white spot aggregates in the corpus may indicate a higher risk of developing diffuse-type gastric cancer. Nodular gastritis may be an indication for eradication therapy to reduce the risk of cancer development after H. pylori eradication.

Intraoperative spinal cord monitoring using combined motor and sensory evoked potentials recorded from the spinal cord during surgery for intramedullary spinal cord tumor.

OBJECTIVES: The risk of postoperative neurological impairment mandates the use of intraoperative spinal cord monitoring (IOM) during intramedullary spinal cord tumor (IMSCT) surgery. We have used spinal cord evoked potential after electrical stimulation of the cord(Sp-SCEP) to monitor the sensory tract, and SCEP after electrical stimulation to the brain (Br-SCEP) to monitor the motor tract. Both Sp-SCEP and Br-SCEP are stable under general anesthesia. We assessed the clinical utility of these multimodal spinal cord monitoring methods in a retrospective study of a cohort of patients undergoing IMSCT surgery. METHODS: Thirteen patients with IMSCTs underwent tumor resection using Sp-SCEP and/or Br-SCEP. RESULTS: Four patients underwent surgery using only Sp-SCEP monitoring, resulting in two false negatives. Nine patients underwent surgery monitored by Br-SCEP and Sp-SCEP. In three of the nine cases, Br-SCEP amplitude fell by 50% from control levels, despite there being no change in Sp-SCEP. In one of the nine cases, Sp-SCEP amplitude fell to 50% of control levels, but Br-SCEP amplitude was stable. CONCLUSIONS: During IMSCT surgery, localized regions of the cord may be damaged. Multimodal monitoring should be used to monitor.Combining Sp-SCEP and Br-SCEP is a useful means of monitoring the sensory and motor tracts.

Surgical site infection in spinal surgery: a comparative study between 2-octyl-cyanoacrylate and staples for wound closure.

BACKGROUND: Surgical site infection (SSI) after spinal surgery is a devastating complication. Various methods of skin closure are used in spinal surgery, but the optimal skin-closure method remains unclear. A recent report recommended against the use of metal staples for skin closure in orthopedic surgery. 2-Octyl-cyanoacrylate (Dermabond; Ethicon, NJ, USA) has been widely applied for wound closure in various surgeries. In this cohort study, we assessed the rate of SSI in spinal surgery using metal staples and 2-octyl-cyanoacrylate for wound closure. METHODS: This study enrolled 609 consecutive patients undergoing spinal surgery in our hospital. From April 2007 to March 2010 surgical wounds were closed with metal staples (group 1, n = 294). From April 2010 to February 2012 skin closure was performed using 2-octyl-cyanoacrylate (group 2, n = 315). We assessed the rate of SSI using these two different methods of wound closure. Prospective study of the time and cost evaluation of wound closure was performed between two groups. RESULTS: Patients in the 2-octyl-cyanoacrylate group had more risk factors for SSI than those in the metal-staple group. Nonetheless, eight patients in the metal-staple group compared with none in the 2-octyl-cyanoacrylate group acquired SSIs (p < 0.01). The closure of the wound in length of 10 cm with 2-octyl-cyanoacrylate could save 28 s and $13.5. CONCLUSIONS: This study reveals that in spinal surgery, wound closure using 2-octyl-cyanoacrylate was associated with a lower rate of SSI than wound closure with staples. Moreover, the use of 2-octyl-cyanoacrylate has a more time saving effect and cost-effectiveness than the use of staples in wound closure of 10 cm in length.

Electrophysiological diagnosis using sensory nerve action potential for the intraforaminal and extraforaminal L5 nerve root entrapment.

BACKGROUND: The diagnosis of lumbar intraforaminal and extraforaminal stenosis (lumbar foraminal stenosis) is sometimes difficult. However, sensory nerve action potential (SNAP) decreases in amplitude when the lesion is at or distal to the dorsal root ganglion. Therefore, the amplitude of SNAP with lumbar foraminal stenosis should be decreased. In this cohort study, the usefulness of SNAP for the preoperative diagnosis of L5/S foraminal stenosis was assessed. METHODS: In 63 patients undergoing unilateral L5 radiculopathy, bilateral SNAPs were recorded for the superficial peroneal nerve (L5 origin). The patients were divided into two groups according to the results of imaging examinations. Group A (37 patients) included patients whose lesion was located only at the intraspinal canal. In group B (26 patients), the lesion was located only at the intra- or extraforaminal area. All patients received surgery and the symptoms were diminished. The ratios of the amplitudes of SNAPs on the affected side to that on the unaffected side were compared between groups A and B. RESULTS: SNAPs could not be elicited bilaterally in four patients. The amplitude ratio for group B (median 0.42, max 1.17, min 0) was significantly lower than that in group A (median 0.85, max 1.43, min 0) (p < 0.001 by Mann-Whitney U test). Using a cut-off value of 0.5 for the amplitude ratio, the sensitivity for the diagnosis of lumbar foraminal stenosis was 91.3 % with a specificity of 85.7 %. CONCLUSIONS: Measurement of SNAP could be useful to diagnose a unilateral L5/S foraminal stenosis.

History of the development of intraoperative spinal cord monitoring.

In the early 1970s, spinal instrumentation and aggressive surgical technology came into wide use for the treatment of severe spinal deformities. This background led to the development of intraoperative spinal cord monitoring by orthopaedic spine surgeons themselves. The author's group (T.T.) and Kurokawa's group invented a technology in 1972 to utilize the spinal cord evoked potential (SCEP) after direct stimulation of the spinal cord. In the United States, Nash and his group started to use SEPs. Following these developments, the Royal National Orthopaedic Hospital group of Stanmore, UK employed spinal somatosensory evoked potential in 1983. However, all of these methods were used to monitor sensory mediated tracts in the spinal cord. The only way to monitor motor function was the Wake up test developed by Vauzelle and Stagnara. In 1980, Merton and Morton reported a technology to stimulate the brain transcranially and opened the doors for motor tract monitoring. Presently, in the operating theatre, monitoring of motor-related functions is routinely performed. We have to remember that multidisciplinary support owing to the development of hardware and, software and the evolution of anesthesiology has made this possible. Furthermore, no single method can sufficiently cover the complex functions of the spinal cord. Multimodality combinations of the available technologies are considered necessary for practical and effective intra-operative monitoring (IOM). In this article, the most notable historic events and articles that are regarded as milestones in the development of IOM are reviewed.

Experimental study of carriers of bone morphogenetic protein used for spinal fusion.

Many materials have been used experimentally as carriers of osteoinductive growth factors. However, there is some doubt about whether the biomechanical strength of the materials affects spinal fusion from early stages of recovery. The aim of this study was to clarify which carrier was biomechanically more effective for bone morphogenetic proteins in spinal fusion. Three biomaterials, each having a different structure and biomechanical strength, were selected as carriers of recombinant human bone morphogenetic protein-2: (1) alpha-tricalcium phosphate cement, which has sufficient biomechanical strength; (2) sintered bovine bone (True Bone Ceramics) coated by type I collagen, which is similar to artificial hydroxyapatite; and (3) type I collagen sheet. Bilateral lumbar intertransverse process arthrodeses were designed in a rabbit model. Spinal fusions were evaluated by radiographic analysis, manual palpation, biomechanics (uniaxial tensile test), and histologic analysis (hematoxylin and eosin, and Villanueva-Goldner's trichrome stains) 3 and 6 weeks after surgery; they were then compared for the three carriers. For achieving the earliest solid spinal fusion, alpha-tricalcium phosphate cement (which has good inherent strength) and True Bone Ceramics (which has good porosity to allow bone penetration) did better than plain collagen (the commonly used carrier).

Trichostatin A activates the osteopontin gene promoter through AP1 site.

In this study, we investigated osteoblastic differentiation by trichostatin A (TSA), a histone deacetylase inhibitor in mouse undifferentiated mesenchymal cell line. TSA increased the osteopontin (OPN) mRNA level and OPN protein. Deletion analysis of the promoter region revealed TSA-induced luciferase response was regulated by -75 to -65 of the OPN promoter. There was an AP1-binding sequence at the site of the OPN promoter. In an electrophoretic mobility shift assay, bands of the complexes were supershifted by addition of antibody to c-fos and phosphorylated c-jun. These data suggested that AP1 plays a crucial role in the TSA-induced OPN expression.

Efficacy and limitations of current methods of intraoperative spinal cord monitoring.

The purpose of this study was to evaluate the efficacy and reliability of intraoperative spinal monitoring using spinal cord-evoked and compound muscle action potentials. We reviewed 716 cases of spinal monitoring performed over 15 years. The series contained 672 patients with spinal functions that could be monitored intraoperatively; 44 (6.1%) were impossible to record. Based on the 21 impossible-to-record patients, it is evident that missing a serious case such as a Frankel B type spinal cord injury indicates the limitations of the current monitoring methods for stimulating and recording. The monitoring outcomes were true-negative in 652 patients, true-positive in 12, false-negative in four, and false-positive in four. In two of the patients with false-negative results, postoperative myelomere motor paralysis was observed temporarily even though it was possible to record the muscle-evoked potential after electrical stimulation to the brain [Br(E)-MsEP] at the end of the operation. In cases in which the spinal parenchyma or spinal nerve root might be selectively damaged, Br(E)-MsEPs may not diagnose the disorder accurately. By employing multimodal monitoring, it should be possible to eliminate patients with false-negative results and to detect spinal disorders during the early stages, as well as to examine whether the abnormality that had been recorded by a single method is false-positive.

Relationships between the changes in compound muscle action potentials and selective injuries to the spinal cord and spinal nerve roots.

OBJECTIVE: Compound muscle action potentials (CMAPs) evoked by transcranial electrical stimulation have been widely introduced to monitor motor function during spinal surgery. They may reflect segmental injuries as well as injuries to motor-related tracts in the spinal cord. However, we have experience with some patients who developed postoperative segmental motor weakness without any potential changes during surgery. To evaluate the efficacy of this method, we used a cat model to observe the relationships between potential changes and selective injuries to the white and gray matters of the spinal cord and spinal nerve roots. METHODS: Ten CMAPs were obtained before and after injury to the spinal cord and spinal nerve roots in 20 cats. Changes in the amplitude, latency, and duration of CMAPs were analyzed. RESULTS: CMAPs decreased in amplitude significantly after the insult to the motor-related tracts in the spinal cord in all cats, while the potentials did not always change when the insult was restricted to a limited area in the anterior horn of the spinal cord or to the single spinal nerve root. CONCLUSIONS: CMAPs may not exactly reflect segmental injury, and careful attention should be paid to the interpretation of CMAPs.

Transdiscal L5-S1 screws for the fixation of isthmic spondylolisthesis: a biomechanical evaluation.

The current study is a biomechanical study using a cadaveric model of L5-S1 spondylolisthesis. The purpose of the current study was to compare, in a cadaveric model of simulated L5-S1 spondylolisthesis, the biomechanical stiffness of transdiscal fixation with traditional pedicle screw fixation, and transdiscal fixation with combined interbody/pedicle screw fixation. The surgical management of L5-S1 spondylolisthesis is a challenge because of the difficulties in achieving a reliable arthrodesis in the face of high mechanical forces. A method of lumbosacral fixation that has been used successfully in moderate grades of spondylolisthesis at our institution involves the use of transdiscal S1 pedicle screws. With this technique, S1 pedicle screws are placed through the S1 pedicle, through the superior endplate of S1, through the inferior endplate of L5, to terminate in the L5 body. Eighteen fresh human cadaveric (age 59-88 years) L5-S1 motion segments were obtained. The end of each intact motion segment was potted up to its midbody in a 10-cm-diameter polyvinylchloride end-cap using dental cement. The intact specimen was then biomechanically tested as follows: 1) axial compression (500 N), 2) flexion (10 Nm), 3) extension (10 Nm), 4) right lateral bending (10 Nm), and 5) left lateral bending (10 Nm). Stiffness values were calculated from the load-deflection curves obtained. Spondylolisthesis was then simulated by displacing L5 on S1 (% slip average = 41.3%) after performing a radical L5-S1 discectomy, L5 laminectomy, and bilateral L5-S1 facetectomies. The 18 motion segments were divided into two groups. Group I (n = 10) was biomechanically tested (as above) after pedicle screw fixation and again after replacing the S1 pedicle screws with transdiscal screws. Group II (n = 8) was biomechanically tested (as above) after combined interbody/pedicle screw fixation and again after fixation with transdiscal screws. Load-deflection curves were obtained each time, and stiffness values were calculated from the curves. Transdiscal fixation was 1.6-1.8 times stiffer than pedicle screw fixation (p < 0.05) in all loading modes tested. There were no differences in stiffness between transdiscal fixation and combined interbody/pedicle screw fixation. In a cadaveric model of simulated L5-S1 spondylolisthesis, transdiscal L5-S1 fixation produced a 1.6-1.8 times stiffer construct than traditional pedicle screw fixation. Further, the stiffness of the transdiscal fixation was equal to that of a combined interbody/pedicle screw fixation.

Comparison of neuropathic pain induced by the application of normal and mechanically compressed nucleus pulposus to lumbar nerve roots in the rat.

We studied whether applying nucleus pulposus tissue, obtained from tail intervertebral discs that had been subjected to chronic mechanical compression, to the lumbar nerve roots produces hyperalgesia, which is thought to be a pain-related behavior in the rat. An Ilizarov-type apparatus was used for immobilization and chronically applied compression of the rat tail for eight weeks. Three weeks after application of extracted nucleus pulposus tissue on the lumbar nerve roots, motor function, sensitivity to noxious mechanical stimuli was measured. Eight weeks after application of the apparatus, the instrumented vertebrae were resected and sections were stained with hematoxylin and eosin to evaluate degeneration of the intervertebral disc. Mechanical hyperalgesia observed in rats treated with the compressed nucleus pulposus tissue was greater and of longer duration than in the rats treated with normal and non-compressed discs. The nucleus pulposus in the instrumented vertebrae showed some histological degeneration. In conclusion, chronic mechanical compression of nucleus pulposus, which resulted in degeneration to some extent, enhanced mechanical hyperalgesia, which was induced by application of nucleus pulposus on the nerve root in the rat. Degenerative intervertebral discs might induce more significant pain than normal intervertebral discs.

A clinical case of endoscopically assisted anterior screw fixation for the type II odontoid fracture.

STUDY DESIGN: A clinical case using a new surgical technique is reported. OBJECTIVE: To report for the first time an endoscopically assisted anterior screw fixation for the Type II odontoid fracture. SUMMARY OF BACKGROUND DATA: Recently, many endoscopically assisted surgeries have been performed for various spinal surgery because of its minimally invasive character. However, the anterior retropharyngeal approach to the upper cervical spine using endoscopy has not been reported. METHODS: A 76-year-old man was operatively managed for a Type II odontoid fracture. The operation was performed under immobilization of cervical spine using a halo vest apparatus. A skin incision 2 cm long was made on the medial border of the right sternocleidomastoid muscle at the C5-C6 intervertebral level. Blunt dissection between the neurovascular bundle laterally and the trachea and esophagus medially was performed. A processed polyethylene syringe (volume, 10 mL) was used as the tubular retractor. This retractor kept the minimum but sufficient space for the screw fixation and avoided esophageal complication. Using a cannulated screw system, a cancellous screw was inserted from the anteroinferior edge of the C2 vertebral body to the tip of the odontoid process. The drilling and the screwing process was monitored by a two-dimensional image intensifier. The entry point was monitored by endoscopy to avoid soft tissue involvement as well. RESULTS: The operation was completed without any soft tissue complications such as esophageal injury. The blood loss was 30 mL. The procedure resulted in nonunion, partially because of patient's old age or an entry point 2 mm above the anterior caudal margin of the C2 body retrospectively. CONCLUSIONS: Although the reported odontoid fracture ended in nonunion, the authors believe their modification of the approach using an endoscope made anterior screw fixation for the odontoid fracture safer and less invasive than the original anterior retropharyngeal approach.