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Sample records for adjacent segment degeneration

  1. Repeated adjacent-segment degeneration after posterior lumbar interbody fusion.

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    Okuda, Shinya; Oda, Takenori; Yamasaki, Ryoji; Maeno, Takafumi; Iwasaki, Motoki

    2014-05-01

    One of the most important sequelae affecting long-term results is adjacent-segment degeneration (ASD) after posterior lumbar interbody fusion (PLIF). Although several reports have described the incidence rate, there have been no reports of repeated ASD. The purpose of this report was to describe 1 case of repeated ASD after PLIF. A 62-year-old woman with L-4 degenerative spondylolisthesis underwent PLIF at L4-5. At the second operation, L3-4 PLIF was performed for L-3 degenerative spondylolisthesis 6 years after the primary operation. At the third operation, L2-3 PLIF was performed for L-2 degenerative spondylolisthesis 1.5 years after the primary operation. Vertebral collapse of L-1 was detected 1 year after the third operation, and the collapse had progressed. At the fourth operation, 3 years after the third operation, vertebral column resection of L-1 and replacement of titanium mesh cages with pedicle screw fixation between T-4 and L-5 was performed. Although the patient's symptoms resolved after each operation, the time between surgeries shortened. The sacral slope decreased gradually although each PLIF achieved local lordosis at the fused segment.

  2. Adjacent segment degeneration: observations in a goat spinal fusion study

    NARCIS (Netherlands)

    R.J.W. Hoogendoorn; M.N. Helder; P.I.J.M. Wuisman; R.A. Bank; V. Everts; T.H. Smit

    2008-01-01

    Study Design. The adjacent discs of 13 goats, originally used in a lumbar spinal fusion model study, were analyzed for symptoms of intervertebral disc degeneration by means of magnetic resonance imaging (MRI), macroscopy, and histology. These goats were followed for 6 months and the results were com

  3. Correlation between sagittal plane changes and adjacent segment degeneration following lumbar spine fusion

    OpenAIRE

    Kumar, Malhar; Baklanov, Andrei; Chopin, Daniel

    2001-01-01

    Adjacent segment degeneration following lumbar spine fusion remains a widely acknowledged problem, but there is insufficient knowledge regarding the factors that contribute to its occurrence. The aim of this study is to analyse the relationship between abnormal sagittal plane configuration of the lumbar spine and the development of adjacent segment degeneration. Eighty-three consecutive patients who underwent lumbar fusion for degenerative disc disease were reviewed retrospectively. Patients ...

  4. Analysis of adjacent segment degeneration with laminectomy above a fused lumbar segment.

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    Gard, Andrew P; Klopper, Hendrik B; Doran, Stephen E; Hellbusch, Leslie C

    2013-11-01

    Although recent data suggests that lumbar fusion with decompression contributes to some marginal acceleration of adjacent segment degeneration (ASD), few studies have evaluated whether it is safe to perform a laminectomy above a fused segment. This study investigates the hypothesis that laminectomy above a fused lumbar segment does not increase the incidence of ASD, and assesses the benefits and risks of performing a laminectomy above a lumbar fusion. A retrospective review of 171 patients who underwent decompression and instrumented fusion of the lumbar spine was performed to analyze the association between ASD and laminectomy above the fused lumbar segment. Patients were divided into two groups - one group with instrumented fusion alone and the other group with instrumented fusion plus laminectomy above the fused segment. Of the 171 patients, 34 underwent additional decompressive laminectomy above the fused segment. There was a significant increase in ASD incidence as well as progression of ASD grade in both groups. There was no significant increase in ASD in patients with decompressive laminectomy above the fused lumbar segment compared to patients with laminectomy limited to the fused segment. This retrospective review of 171 patients who underwent decompression and instrumented fusion with follow-up radiographs demonstrates that laminectomy decompression above a fused segment does not significantly increase radiographic ASD. There is, however, a significant increase in ASD over time, which was observed throughout the entire cohort likely representing a natural progression of lumbar spondylosis above the fusion segment.

  5. Comparison of adjacent segment degeneration five years after single level cervical fusion and cervical arthroplasty:a retrospective controlled study

    Institute of Scientific and Technical Information of China (English)

    SUN Yu; ZHAO Yan-bin; PAN Sheng-fa; ZHOU Fei-fei; CHEN Zhong-qiang; LIU Zhong-jun

    2012-01-01

    Background Cervical arthroplasty is indicated to preserve cervical motion and prevent accelerated adjacent segment degeneration.Whether accelerated adjacent segment degeneration is prevented in the long term is unclear.This trial compared adjacent segment degeneration in Bryan disc arthroplasty with that in anterior cervical decompression and fusion five years after the surgery.Methods We studied patients with single level degenerative cervical disc disease.The extent of adjacent segment degeneration was estimated from lateral X-rays.Results Twenty-six patients underwent single level Bryan disc arthroplasty and twenty-four patients underwent single level anterior cervical decompression and fusion.All patients were followed up for an average of sixty months.In the Bryan arthroplasty group,nine(17.6%)segments developed adjacent segment degeneration,which was significantly lower than that(60.4%)in the anterior cervical decompression and fusion group.Eleven segments in the Bryan arthroplasty group developed heterotopic ossification according to McAfee's classification and two segments had range of motion less than 2°.In the heterotopic ossification group,four(19.5%)segments developed adjacent segment degeneration,similar to the number in the non-heterotopic ossification group(16.7%).Adjacent segment degeneration rate was 50% in gradeⅣ?group but 11.8% in gradeⅡ?to Ⅲ.Conclusions Adjacent segment degeneration was accelerated after anterior cervical decompression and fusion.However,Bryan disc arthroplasty avoided accelerated adjacent segment degeneration by preserving motion.Patients with gradeⅣ?heterotopic ossification lost motion,and the rate of adjacent segment degeneration was higher than that in patients without heterotopic ossification.

  6. Risk factors for adjacent segment degeneration after surgical correction of degenerative lumbar scoliosis

    Directory of Open Access Journals (Sweden)

    Kee-yong Ha

    2013-01-01

    Full Text Available Background: Degenerative lumbar scoliosis surgery can lead to development of adjacent segment degeneration (ASD after lumbar or thoracolumbar fusion. Its incidence, risk factors, morbidity and correlation between radiological and clinical symptoms of ASD have no consensus. We evaluated the correlation between the occurrence of radiologic adjacent segment disease and certain imperative parameters. Materials and Methods: 98 patients who had undergone surgical correction and lumbar/thoracolumbar fusion with pedicle screw instrumentation for degenerative lumbar scoliosis with a minimum 5 year followup were included in the study. We evaluated the correlation between the occurrence of radiologic adjacent segment disease and imperative patient parameters like age at operation, sex, body mass index (BMI, medical comorbidities and bone mineral density (BMD. The radiological parameters taken into consideration were Cobb′s angle, angle type, lumbar lordosis, pelvic incidence, intercristal line, preoperative existence of an ASD on plain radiograph and magnetic resonance imaging (MRI and surgical parameters were number of the fusion level, decompression level, floating OP (interlumbar fusion excluding L5-S1 level and posterolateral lumbar interbody fusion (PLIF. Clinical outcomes were assessed with the Visual Analogue Score (VAS and Oswestry Disability Index (ODI. Results: ASD was present in 44 (44.9% patients at an average period of 48.0 months (range 6-98 months. Factors related to occurrence of ASD were preoperative existence of disc degeneration (as revealed by MRI and age at operation ( P = 0.0001, 0.0364. There were no statistically significant differences between radiological adjacent segment degeneration and clinical results (VAS, P = 0.446; ODI, P = 0.531. Conclusions: Patients over the age of 65 years and with preoperative disc degeneration (as revealed by plain radiograph and MRI were at a higher risk of developing ASD.

  7. Risk factors for predicting symptomatic adjacent segment degeneration requiring surgery in patients after posterior lumbar fusion

    OpenAIRE

    Liang, Jinqian; Dong, Yulei; Zhao, Hong

    2014-01-01

    Background Although measures to reduce and treat degenerative changes after fusion are discussed, these are still controversial. Methods A retrospective study was conducted on a consecutive series of 3,799 patients who underwent posterior lumbar fusion for degenerative lumbar disease between January 1999 and January 2009. A total of 28 patients with symptomatic adjacent segment degeneration surgery were identified. Another group of 56 matched patients with degenerative lumbar disease without ...

  8. The incidence of adjacent segment degeneration after cervical disc arthroplasty (CDA: a meta analysis of randomized controlled trials.

    Directory of Open Access Journals (Sweden)

    Baohui Yang

    Full Text Available BACKGROUND: Cervical disc arthroplasty is being used as an alternative degenerative disc disease treatment with fusion of the cervical spine in order to preserve motion. However, whether replacement arthoplasty in the spine achieves its primary patient centered objective of lowering the frequency of adjacent segment degeneration is not verified yet. METHODOLOGY: We conducted a meta-analysis according to the guidelines of the Cochrane Collaboration using databases including PubMed, Cochrane Central Register of Controlled Trials and Embase. The inclusion criteria were: 1 Randomized, controlled study of degenerative disc disease of the cervical spine involving single segment or double segments using Cervical disc arthroplasty (CDA with anterior cervical discectomy and fusion (ACDF as controls; 2 A minimum of two-year follow-up using imaging and clinical analyses; 3 Definite diagnostic evidences for "adjacent segment degeneration" and "adjacent segment disease"; 4 At least a minimum of 30 patients per population. Two authors independently selected trials; assessed methodological quality, extracted data and the results were pooled. RESULTS: No study has specifically compared the results of adjacent segment degenerative; Two papers describing 140 patients with 162 symptomatic cervical segment disorders and compared the rate of postoperative adjacent segment disease development between CDA and ACDF treatments, three publications describing the rate of adjacent-segment surgery including 1273 patients with symptomatic cervical segments. The result of the meta-analysis indicates that there were fewer the rate of adjacent segment disease and the rate for adjacent-segment surgery comparing CDA with ACDF, but the difference was not statistically significant. CONCLUSIONS: Based on available evidence, it cannot be concluded, that CDA can significantly reduce the postoperative rate of the adjacent segment degenerative and adjacent segment disease. However, due

  9. Protective effect of calcitonin on lumbar fusion-induced adjacent-segment disc degeneration in ovariectomized rat

    OpenAIRE

    Liu, Chang-Cheng; Tian, Fa-Ming; Zhou, Zhuang; Wang, Peng; Gou, Yu; Zhang, Heng; Wang, Wen-Ya; Shen, Yong; Zhang, Ying-Ze; Zhang, Liu

    2015-01-01

    Background Intervertebral disc (IVD) degeneration and pathological changes in the spinal cord are major causes of back pain. In addition to its well-established anti-resorptive effect on bone, calcitonin (CT) potentially exerts protective effects on IVD degeneration in ovariectomized rats. However, possible therapeutic effects of CT on lumbar fusion-induced adjacent-segment disc degeneration (ASDD) have not been investigated yet. In this study, we examined the effects of CT on IVD degeneratio...

  10. Cervicothoracic junction arthroplasty after previous fusion surgery for adjacent segment degeneration: case report.

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    Sekhon, Lali

    2005-01-01

    This is the first reported case of cervical arthroplasty using the Bryan Cervical Disc Prosthesis System (Medtronic Sofamor Danek, Inc., Memphis, TN) in the management of adjacent segment degeneration associated with previous fusion surgery and surgery at the cervicothoracic junction. This case report describes a 25-year-old woman who initially underwent a two-level anterior cervical fusion in 1998, 2 years after being involved in a motor vehicle accident. She was well until 18 months before presentation, when she developed bilateral shoulder pain, mechanical neck pain worse on flexion, and bilateral C8 distribution arm pain and paresthesia. On clinical examination, no focal deficits were found, although the range of motion was reduced. Preoperative cervical spine x-rays and magnetic resonance scanning confirmed accelerated degeneration of the C4-C5 and C7-T1 disc spaces, with evidence of neural compression at those levels. After careful consideration of various treatment options and failure of all conservative measures, the patient underwent an anterior C4-C5 and C7-T1 decompression with removal of the anterior cervical plate and placement of two artificial disc prostheses. After surgery, her course was uncomplicated and she was discharged from hospital well. There was complete resolution of the arm symptoms and reduction of the neck pain, with a reduction in the amount of analgesia she was taking. Seven months after surgery, she remains well with repeat x-rays confirming motion at the operated levels. This case demonstrates that cervical arthroplasty is a reasonable treatment option for patients who have had previous surgery in which interbody fusion has been performed and who have developed degeneration of adjacent levels. Despite the altered biomechanics at the cervicothoracic junction, no adverse features were noted with arthroplasty at this level.

  11. Reduction in adjacent-segment degeneration after multilevel posterior lumbar interbody fusion with proximal DIAM implantation.

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    Lu, Kang; Liliang, Po-Chou; Wang, Hao-Kuang; Liang, Cheng-Loong; Chen, Jui-Sheng; Chen, Tai-Been; Wang, Kuo-Wei; Chen, Han-Jung

    2015-08-01

    OBJECT Multilevel long-segment lumbar fusion poses a high risk for future development of adjacent-segment degeneration (ASD). Creating a dynamic transition zone with an interspinous process device (IPD) proximal to the fusion has recently been applied as a method to reduce the occurrence of ASD. The authors report their experience with the Device for Intervertebral Assisted Motion (DIAM) implanted proximal to multilevel posterior lumbar interbody fusion (PLIF) in reducing the development of proximal ASD. METHODS This retrospective study reviewed 91 cases involving patients who underwent 2-level (L4-S1), 3-level (L3-S1), or 4-level (L2-S1) PLIF. In Group A (42 cases), the patients received PLIF only, while in Group B (49 cases), an interspinous process device, a DIAM implant, was put at the adjacent level proximal to the PLIF construct. Bone resection at the uppermost segment of the PLIF was equally limited in the 2 groups, with preservation of the upper portion of the spinous process/lamina and the attached supraspinous ligament. Outcome measures included a visual analog scale (VAS) for low-back pain and leg pain and the Oswestry Disability Index (ODI) for functional impairment. Anteroposterior and lateral flexion/extension radiographs were used to evaluate the fusion status, presence and patterns of ASD, and mobility of the DIAM-implanted segment. RESULTS Solid interbody fusion without implant failure was observed in all cases. Radiographic ASD occurred in 20 (48%) of Group A cases and 3 (6%) of Group B cases (p Group A and 3 in Group B were symptomatic; of these patients, 3 in Group A and 1 in Group B underwent a second surgery for severe symptomatic ASD. At 24 months after surgery, Group A patients fared worse than Group B, showing higher mean VAS and ODI scores due to symptoms related to ASD. At the final follow-up evaluations, as reoperations had been performed to treat symptomatic ASD in some patients, significant differences no longer existed between the 2

  12. In-Depth Analysis on Influencing Factors of Adjacent Segment Degeneration After Cervical Fusion

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    Yu, Chaojie; Mu, Xiaoping; Wei, Jianxun; Chu, Ye; Liang, Bin

    2016-01-01

    Background To explore the related influencing factors of adjacent segment degeneration (ASD) after cervical discectomy and fusion (ACDF). Material/Methods A retrospective analysis of 263 patients who underwent ACDF was carried out. Cervical x-ray and magnetic resonance imaging (MRI) were required before operation, after operation, and at the last follow-up. General information and some radiographic parameters of all patients were measured and recorded. According to the imaging data, patients were put into one of two groups: non-ASD group and ASD group. The differences between the two groups were compared by t-test and χ2-test, and the related influencing factors of ASD were analyzed by logistic regression. Results In all, 138 patients had imaging ASD. Comparing the age, the postoperative cervical arc chord distance (po-CACD), and the plate to disc distance (PDD) of the two groups, differences were statistically significant (pspinal canal ratio, and the upper and lower disc height (DH) showed no statistical difference between the two groups (p>0.05). The results of logistic regression analysis showed that there were significant correlations in the following characteristics: age, postoperative po-CACD, and the PDD (pcurvature of cervical spine, and a PDD < 5 mm was more likely to lead to ASD. PMID:27965512

  13. Adjacent segment disease.

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    Virk, Sohrab S; Niedermeier, Steven; Yu, Elizabeth; Khan, Safdar N

    2014-08-01

    EDUCATIONAL OBJECTIVES As a result of reading this article, physicians should be able to: 1. Understand the forces that predispose adjacent cervical segments to degeneration. 2. Understand the challenges of radiographic evaluation in the diagnosis of cervical and lumbar adjacent segment disease. 3. Describe the changes in biomechanical forces applied to adjacent segments of lumbar vertebrae with fusion. 4. Know the risk factors for adjacent segment disease in spinal fusion. Adjacent segment disease (ASD) is a broad term encompassing many complications of spinal fusion, including listhesis, instability, herniated nucleus pulposus, stenosis, hypertrophic facet arthritis, scoliosis, and vertebral compression fracture. The area of the cervical spine where most fusions occur (C3-C7) is adjacent to a highly mobile upper cervical region, and this contributes to the biomechanical stress put on the adjacent cervical segments postfusion. Studies have shown that after fusion surgery, there is increased load on adjacent segments. Definitive treatment of ASD is a topic of continuing research, but in general, treatment choices are dictated by patient age and degree of debilitation. Investigators have also studied the risk factors associated with spinal fusion that may predispose certain patients to ASD postfusion, and these data are invaluable for properly counseling patients considering spinal fusion surgery. Biomechanical studies have confirmed the added stress on adjacent segments in the cervical and lumbar spine. The diagnosis of cervical ASD is complicated given the imprecise correlation of radiographic and clinical findings. Although radiological and clinical diagnoses do not always correlate, radiographs and clinical examination dictate how a patient with prolonged pain is treated. Options for both cervical and lumbar spine ASD include fusion and/or decompression. Current studies are encouraging regarding the adoption of arthroplasty in spinal surgery, but more long

  14. Impact of T1 slope on surgical and adjacent segment degeneration after Bryan cervical disc arthroplasty.

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    Yang, Peng; Li, Yongqian; Li, Jia; Shen, Yong

    2017-01-01

    This retrospective study investigated an association between preoperative T1 slope and surgical and adjacent segment degeneration (SASD) after Bryan cervical disc arthroplasty (BCDA) in patients with cervical degenerative disc disease. Based on preoperative standing lateral radiographs, 90 patients were classified according to T1 slope that was higher or lower than the 50th percentile (high T1 or low T1, 28 and 62 patients, respectively). Patients were also classified as SASD or non-SASD (38 and 52 patients, respectively) determined by radiographs at final follow-up. Visual analog scale (VAS) and Neck Disability Index (NDI) scores for neck and arm pain were noted, and changes in the sagittal alignment of the cervical spine (SACS), functional spinal unit (FSU) angle, and FSU range of motion (ROM) were also noted. Univariate and multivariate logistic regression analyses were performed to determine the risk factors for SASD. The overall rate of SASD was 42.2% (38/90). The SACS, FSU angle, FSU ROM, and SASD rates of the high T1 and low T1 slope groups were significantly different at the last follow-up. The NDI and VAS scores of the high T1 slope group were significantly greater than those of the low T1 slope. The multivariate logistic regression analysis showed that high T1 slope and endplate coverage discrepancy (ie, residual space behind the prosthesis) were significant risk factors for SASD after BCDA. High T1 slope and endplate coverage discrepancy were associated with SASD after BCDA. Patients with a high preoperative T1 slope have a smaller FSU angle and more neck pain after BCDA.

  15. The Incidence of Adjacent Segment Degeneration after Cervical Disc Arthroplasty (CDA): A Meta Analysis of Randomized Controlled Trials

    OpenAIRE

    Baohui Yang; Haopeng Li; Ting Zhang; Xijing He; Siyue Xu

    2012-01-01

    BACKGROUND: Cervical disc arthroplasty is being used as an alternative degenerative disc disease treatment with fusion of the cervical spine in order to preserve motion. However, whether replacement arthoplasty in the spine achieves its primary patient centered objective of lowering the frequency of adjacent segment degeneration is not verified yet. METHODOLOGY: We conducted a meta-analysis according to the guidelines of the Cochrane Collaboration using databases including PubMed, Cochrane Ce...

  16. Prevalence of adjacent segment disc degeneration in patients undergoing anterior cervical discectomy and fusion based on pre-operative MRI findings.

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    Lundine, Kristopher M; Davis, Gavin; Rogers, Myron; Staples, Margaret; Quan, Gerald

    2014-01-01

    Anterior cervical discectomy and fusion (ACDF) is a widely accepted surgical treatment for symptomatic cervical spondylosis. Some patients develop symptomatic adjacent segment degeneration, occasionally requiring further treatment. The cause and prevalence of adjacent segment degeneration and disease is unclear at present. Proponents for motion preserving surgery such as disc arthroplasty argue that this technique may decrease the "strain" on adjacent discs and thus decrease the incidence of symptomatic adjacent segment degeneration. The purpose of this study was to assess the pre-operative prevalence of adjacent segment degeneration in patients undergoing ACDF. A database review of three surgeons' practice was carried out to identify patients who had undergone a one- or two-level ACDF for degenerative disc disease. Patients were excluded if they were operated on for recent trauma, had an inflammatory arthropathy (for example, rheumatoid arthritis), or had previous spine surgery. The pre-operative MRI of each patient was reviewed and graded using a standardised methodology. One hundred and six patient MRI studies were reviewed. All patients showed some evidence of intervertebral disc degeneration adjacent to the planned operative segment(s). Increased severity of disc degeneration was associated with increased age and operative level, but was not associated with sagittal alignment. Disc degeneration was more common at levels adjacent to the surgical level than at non-adjacent segments, and was more severe at the superior adjacent level compared with the inferior adjacent level. These findings support the theory that adjacent segment degeneration following ACDF is due in part to the natural history of cervical spondylosis.

  17. Magnetic resonance imaging on disc degeneration changes after implantation of an interspinous spacer and fusion of the adjacent segment.

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    Liu, Xiaokang; Liu, Yingjie; Lian, Xiaofeng; Xu, Jianguang

    2015-01-01

    The aim of the study was to investigate the changes of the lumbar intervertebral disc degeneration by magnetic resonance imaging (MRI) after the implantation of interspinous device and the fusion of the adjacent segment. A total of 62 consecutive patients suffering L5/S1 lumbar disc herniation (LDH) with concomitant disc space narrowing or low-grade instability up to 5 mm translational slip in L5/S1 level were treated with lumbar interbody fusion (LIF) via posterior approach. Thirty-four of these patients (Coflex group) received an additional implantation of the interspinous spacer device (Coflex™) in the level L4/L5, while the rest of 28 patients (fusion group) underwent the fusion surgery alone. Clinical and radiographic examinations were performed at pre- and postoperative visits to compare the clinical outcomes and the changes of the L4/L5 vertebral disc degeneration on MRI in both Coflex and fusion group. Although both Coflex and fusion group showed improvements of the clinical outcomes assessed by the Oswestry Disability Index (ODI) after surgery, patients in Coflex group had more significant amelioration (P degeneration changes in Coflex group assessed by the relative signal intensity (RSI) differed from those in fusion group (P degeneration of the adjacent segment.

  18. Biomechanical analysis of lateral interbody fusion strategies for adjacent segment degeneration in the lumbar spine.

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    Metzger, Melodie F; Robinson, Samuel T; Maldonado, Ruben C; Rawlinson, Jeremy; Liu, John; Acosta, Frank L

    2017-07-01

    Surgical treatment of symptomatic adjacent segment disease (ASD) typically involves extension of previous instrumentation to include the newly affected level(s). Disruption of the incision site can present challenges and increases the risk of complication. Lateral-based interbody fusion techniques may provide a viable surgical alternative that avoids these risks. This study is the first to analyze the biomechanical effect of adding a lateral-based construct to an existing fusion. The study aimed to determine whether a minimally invasive lateral interbody device, with and without supplemental instrumentation, can effectively stabilize the rostral segment adjacent to a two-level fusion when compared with a traditional posterior revision approach. This is a cadaveric biomechanical study of lateral-based interbody strategies as add-on techniques to an existing fusion for the treatment of ASD. Twelve lumbosacral specimens were non-destructively loaded in flexion, extension, lateral bending, and torsion. Sequentially, the tested conditions were intact, two-level transforaminal lumbar interbody fusion (TLIF) (L3-L5), followed by lateral lumbar interbody fusion procedures at L2-L3 including interbody alone, a supplemental lateral plate, a supplemental spinous process plate, and then either cortical screw or pedicle screw fixation. A three-level TLIF was the final instrumented condition. In all conditions, three-dimensional kinematics were tracked and range of motion (ROM) was calculated for comparisons. Institutional funds (Medtronic Spine. The addition of a lateral interbody device superadjacent to a two-level fusion significantly reduced motion in flexion, extension, and lateral bending (pfusion construct, demonstrating ROM comparable with a traditional three-level TLIF. The data presented suggest that a lateral-based interbody fusion supplemented with additional minimally invasive instrumentation may provide comparable stability with a traditional posterior revision

  19. Enhancement of Lumbar Fusion and Alleviation of Adjacent Segment Disc Degeneration by Intermittent PTH(1-34) in Ovariectomized Rats.

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    Zhou, Zhuang; Tian, Fa-Ming; Gou, Yu; Wang, Peng; Zhang, Heng; Song, Hui-Ping; Shen, Yong; Zhang, Ying-Ze; Zhang, Liu

    2016-04-01

    Osteoporosis, which is prevalent in postmenopausal or aged populations, is thought to be a contributing factor to adjacent segment disc degeneration (ASDD), and the incidence and extent of ASDD may be augmented by osteopenia. Parathyroid hormone (PTH) (1-34) has already been shown to be beneficial in osteoporosis, lumbar fusion and matrix homeostasis of intervertebral discs. However, whether PTH(1-34) has a reversing or retarding effect on ASDD in osteopenia has not been confirmed. In the present study, we evaluated the effects of intermittent PTH(1-34) on ASDD in an ovariectomized (OVX) rat model. One hundred 3-month-old female Sprague-Dawley rats underwent L4 -L5 posterolateral lumbar fusion (PLF) with spinous-process wire fixation 4 weeks after OVX surgery. Control groups were established accordingly. PTH(1-34) was intermittently administered immediately after PLF surgery and lasted for 8 weeks using the following groups (n = 20) (V = vehicle): Sham+V, OVX+V, Sham+PLF+V, OVX+PLF+V, OVX+PLF+PTH. The fused segments showed clear evidence of eliminated motion on the fusion-segment based on manual palpation. Greater new bone formation in histology was observed in PTH-treated animals compared to the control group. The extent of ASDD was significantly increased by ovariotomy. Intermittent PTH(1-34) significantly alleviated ASDD by preserving disc height, microvessel density, relative area of vascular buds, endplate thickness and the relative area of endplate calcification. Moreover, protein expression results showed that PTH(1-34) not only inhibited matrix degradation by decreasing MMP-13, ADAMTS-4 and Col-I, but also promote matrix synthesis by increasing Col-II and Aggrecan. In conclusion, PTH(1-34), which effectively improves lumbar fusion and alleviates ASDD in ovariectomized rats, may be a potential candidate to ameliorate the prognosis of lumbar fusion in osteopenia.

  20. The Efficacy of Lumbar Hybrid Stabilization Using the DIAM™ to Delay Adjacent Segment Degeneration: An Intervention Comparison Study With a Minimum Two-Year Follow-up.

    Science.gov (United States)

    Lee, Chang-Hyun; Hyun, Seung-Jae; Kim, Ki-Jeong; Jahng, Tae-Ahn; Yoon, Sang Hoon; Kim, Hyun-Jib

    2013-04-29

    BACKGROUND:: Although posterior lumbar interbody fusion (PLIF) has a successful fusion rate, the long-term outcome of PLIF is occasionally below expectations because of adjacent segment degeneration (ASD). OBJECTIVE:: To evaluate the ability of hybrid stabilization using DIAM(Device for Interspinous Assisted Motion) to delay ASD. METHODS:: An intervention comparison study of 75 patients (hybrid, 25; PLIF, 50) was performed. The indications for hybrid stabilization were facet joint degeneration, Pfirrmann grade II-III, and stenosis at the rostral adjacent segment. The PLIF group consisted of patients matched for age, gender, and fusion. The hybrid stabilization procedure included traditional PLIF and DIAM installation at a superior adjacent segment. The outcomes were analyzed using linear mixed model analysis. Conditional logistic regression was performed to calculate the odds ratio for the association of surgical methods. RESULTS:: The hybrid group (24%) revealed fewer ASDs than the PLIF group (48%). Among ASDs, spondylolisthesis occurred more frequently in the PLIF group than the hybrid group. Hybrid surgery was significantly associated with ASD; the odds ratio for hybrid surgery was 0.28 when compared to PLIF. Foraminal height of the PLIF group decreased more than the hybrid group (P=.01). Segmental mobility showed a greater increase in the PLIF group than the hybrid group (P=.04). However, the clinical outcomes did not show significant differences between the groups. CONCLUSION:: Hybrid stabilization using DIAM and pedicle screws can be used for patients with facet degeneration at adjacent segments but should be further investigated.

  1. Comparison of percutaneous endoscopic lumbar discectomy and open lumbar surgery for adjacent segment degeneration and recurrent disc herniation.

    Science.gov (United States)

    Chen, Huan-Chieh; Lee, Chih-Hsun; Wei, Li; Lui, Tai-Ngar; Lin, Tien-Jen

    2015-01-01

    Objective. The goal of the present study was to examine the clinical results of percutaneous endoscopic lumbar discectomy (PELD) and open lumbar surgery for patients with adjacent segment degeneration (ASD) and recurrence of disc herniation. Methods. From December 2011 to November 2013, we collected forty-three patients who underwent repeated lumbar surgery. These patients, either received PELD (18 patients) or repeated open lumbar surgery (25 patients), due to ASD or recurrence of disc herniation at L3-4, L4-5, or L5-S1 level, were assigned to different groups according to the surgical approaches. Clinical data were assessed and compared. Results. Mean blood loss was significantly less in the PELD group as compared to the open lumbar surgery group (P < 0.0001). Hospital stay and mean operating time were shorter significantly in the PELD group as compared to the open lumbar surgery group (P < 0.0001). Immediate postoperative pain improvement in VAS was 3.5 in the PELD group and -0.56 in the open lumbar surgery group (P < 0.0001). Conclusion. For ASD and recurrent lumbar disc herniation, PELD had more advantages over open lumbar surgery in terms of reduced blood loss, shorter hospital stay, operating time, fewer complications, and less postoperative discomfort.

  2. Comparison of Percutaneous Endoscopic Lumbar Discectomy and Open Lumbar Surgery for Adjacent Segment Degeneration and Recurrent Disc Herniation

    Directory of Open Access Journals (Sweden)

    Huan-Chieh Chen

    2015-01-01

    Full Text Available Objective. The goal of the present study was to examine the clinical results of percutaneous endoscopic lumbar discectomy (PELD and open lumbar surgery for patients with adjacent segment degeneration (ASD and recurrence of disc herniation. Methods. From December 2011 to November 2013, we collected forty-three patients who underwent repeated lumbar surgery. These patients, either received PELD (18 patients or repeated open lumbar surgery (25 patients, due to ASD or recurrence of disc herniation at L3-4, L4-5, or L5-S1 level, were assigned to different groups according to the surgical approaches. Clinical data were assessed and compared. Results. Mean blood loss was significantly less in the PELD group as compared to the open lumbar surgery group P<0.0001. Hospital stay and mean operating time were shorter significantly in the PELD group as compared to the open lumbar surgery group P<0.0001. Immediate postoperative pain improvement in VAS was 3.5 in the PELD group and −0.56 in the open lumbar surgery group P<0.0001. Conclusion. For ASD and recurrent lumbar disc herniation, PELD had more advantages over open lumbar surgery in terms of reduced blood loss, shorter hospital stay, operating time, fewer complications, and less postoperative discomfort.

  3. Fusion of Adjacent Segment Degeneration after Anterior Portion Cervical Decompression%颈前路融合术后相邻节段退变120例

    Institute of Scientific and Technical Information of China (English)

    占蓓蕾; 叶舟

    2014-01-01

    目的:探讨颈椎前路减压融合术后相邻节段退变的因果关系。方法:对237例患者行前路椎间节段减压植骨融合术(87例),椎体次全切除减压植骨融合术(109例),椎间节段减压、椎体次全切除减压植骨融合术(41例)。通过影像学检查,观察不同手术方法术后相邻节段退变发生情况。结果:术后随访时间2.6~13年,平均6.8年;发生相邻节段明显退变的120例(50.6%),头侧相邻节段退变发生率明显高于尾侧邻近节段(P<0.05),其中27例(22.2%)需2次翻修手术。结论:颈椎前路融合术后可导致颈椎相邻节段的退变。%Objective To investigate the result of anterior cervical decompression and fusion of adjacent segment degeneration after causality. Methods among 237 patients(87 cases) weretreated with anterior decom-pression and interbody fusion intervertebral segments, 109cases with subtotal excision of the vertebral body with decompression and interbody fusion,and 41 cases with intervertebral segmental decompression, vertebral body subtotal resection decompression and interbody fusion.By imaging examination, different surgical methods and postoperative adjacent segment degeneration were observed. Results Postoperative follow-up at time of 2.6~13 years, averaging 6.8 years; showed significantly degeneration of adjacent segments in 120 cases (50.6%), the cranial adjacent segment degeneration rate significantly higher than that of the caudal adjacent segment (P<0.05), among them,27 cases (22.2%)needed 2 times of revision surgery. Conclusion The anterior cervical fu-sion surgery can lead to cervical vertebral adjacent segment degeneration.

  4. Dynesys 动态固定系统与腰椎相邻节段退变的研究进展%Research progress of Dynesys dynamic stabilization system and lumbar adjacent segment degeneration

    Institute of Scientific and Technical Information of China (English)

    张阳; 李放

    2013-01-01

      In recent years, the lumbar non-fusion technique remains a hot research topic in spine surgery, and the Dynesys dynamic stabilization system is one of the most widely applied non-fusion techniques clinically. The system is designed to stabilize the operated segments and meanwhile preserve some mobility, so as to prevent the stress concentration of adjacent segments and relieve adjacent segment degeneration. Many clinical studies show that the Dynesys system could have satisfied clinical results, but at present there are still some controversies about the role of the Dynesys dynamic stabilization system in reducing adjacent segment degeneration. The biomechanical and clinical research about the role of the Dynesys system in preventing adjacent segment degeneration is reviewed in this article, to provide clinical evidence.

  5. Induction of early degeneration of the adjacent segment after posterior lumbar interbody fusion by excessive distraction of lumbar disc space.

    Science.gov (United States)

    Kaito, Takashi; Hosono, Noboru; Mukai, Yoshihiro; Makino, Takahiro; Fuji, Takeshi; Yonenobu, Kazuo

    2010-06-01

    Spinal fusion at the L4-5 disc space alters the normal biomechanics of the spine, and the loss of motion at the fused level is compensated by increased motion and load at the other unfused segments. This may lead to deterioration of the adjacent segments of the lumbar spine, called adjacent-segment disease (ASD). In this study, the authors investigate the distracted disc height of the fused segment, caused by cage or bone insertion during surgery, as a novel risk factor for ASD after posterior lumbar interbody fusion (PLIF). Radiographic L3-4 ASD is defined by development of spondylolisthesis greater than 3 mm, a decrease in disc height of more than 3 mm, or intervertebral angle at flexion smaller than -5 degrees . Symptomatic ASD is defined by a decrease of 4 points or more on the Japanese Orthopaedic Association scale. Eighty-five patients with L-4 spondylolisthesis treated by L4-5 PLIF underwent follow-up for more than 2 years (mean 38.8 +/- 17.1 months). The patients were divided into 3 groups according to the final outcome. Group A comprised those patients without ASD (58), Group B patients had radiographic ASD (14), and Group C patients had symptomatic ASD (13). The L4-5 disc space distraction by cage insertion was 3.1 mm in the group without ASD, 4.4 mm in the group with radiographic ASD, and 6.2 mm in the group with symptomatic ASD, as measured using lateral spinal radiographs just after surgery. Multivariate analysis showed that distraction was the most significant risk factor. The excessive distraction of the L4-5 disc space during PLIF surgery is a significant and potentially avoidable risk factor for the development of radiographic, symptomatic ASD.

  6. Clinical Research Status of Adjacent Segment Degeneration After Lumbar Spinal Fusion%腰椎融合术后邻近节段退变的临床研究现状

    Institute of Scientific and Technical Information of China (English)

    张波; 李伟; 苟林; 李亮; 张兵; 吴辉; 林宏

    2015-01-01

    ObjectiveClinical research status of adjacent segment degeneration after lumbar fusion analysis.Methods The clinical data of adjacent segment degeneration collected in our hospital in recent years appeared after lumbar fusion, research status of adjacent segment degeneration after lumbar fusion and comprehensive analysis. Results The concept of adjacent segment degeneration included imaging of adjacent segment degeneration of adjacent segment degeneration and clinical symptoms, the incidence of a minimum of 8% of the former, up to 95%, the lowest incidence of clinical symptoms for 5.2% adjacent segment degeneration, a maximum of 18.5%. For adjacent segment degeneration prevention measures include: to reduce intraoperative fusion segments, application of non fusiontechnology, sagittal balance etc. ConclusionAfter lumbar fusion is prone to adjacent segment degeneration, the patients with application of non fusion technology can signiifcantly reduce the incidence of adjacent segment degeneration.%目的:分析腰椎融合术后邻近节段退变的临床研究现状。方法收集我院近年来出现的腰椎融合术后邻近节段退变的临床资料,综合分析腰椎融合术后邻近节段退变的研究现状。结果邻近节段退变的概念包括影像学邻近节段退变和临床症状邻近节段退变,前者的发生率最低为8%,最高可达到95%,临床症状邻近节段退变的发生率最低为5.2%,最高为18.5%。对于邻近节段退变的预防措施主要有:术中减少融合节段、应用非融合技术、维持矢状面平衡等等。结论腰椎融合术后很容易发生邻近节段退变,通过对患者应用非融合技术可显著减少邻近节段退变的发生。

  7. Analysis of adjacent segment reoperation after lumbar total disc replacement

    OpenAIRE

    Rainey, Scott; Blumenthal, Scott L.; Zigler, Jack E.; Guyer, Richard D.; Ohnmeiss, Donna D.

    2012-01-01

    Background Fusion has long been used for treating chronic back pain unresponsive to nonoperative care. However, potential development of adjacent segment degeneration resulting in reoperation is a concern. Total disc replacement (TDR) has been proposed as a method for addressing back pain and preventing or reducing adjacent segment degeneration. The purpose of the study was to determine the reoperation rate at the segment adjacent to a level implanted with a lumbar TDR and to analyze the pre-...

  8. Adjacent segment degeneration after single-level anterior cervical decompression and fusion: disc space distraction and its impact on clinical outcomes.

    Science.gov (United States)

    Li, Jia; Li, Yongqian; Kong, Fanlong; Zhang, Di; Zhang, Yingze; Shen, Yong

    2015-03-01

    The purpose of this study was to find whether excessive distraction of the disc space for cage insertion was a risk factor for adjacent segment degeneration (ASD) after anterior cervical decompression and fusion (ACDF). One hundred and sixteen consecutive patients who underwent ACDF for single-level cervical disc herniation between June 2006 and November 2008 were retrospectively reviewed. Preoperative, postoperative and final follow-up disc height (DH), sagittal segmental alignment (SSA), and sagittal alignment of the cervical spine (SACS) were measured and compared between the ASD group and non-ASD group. In 116 patients, ASD was radiographically proven in 28 (24.1%) patients. The clinical outcomes were significantly improved compared to the preoperative scores in both groups. However, the postoperative and final follow-up DH of the ASD group were significantly higher than in the non-ASD group (p<0.05). In addition, the postoperative DH was significantly correlated with the postoperative or final follow-up SSA (p<0.05). However, postoperative DH was not found to significantly correlate with postoperative or final follow-up SACS (p=0.072 and p=0.096, respectively). Multivariate analysis showed that postoperative DH was the most significant risk factor for ASD. The clinical outcomes of ACDF for single-level degenerative cervical disc disease were satisfactory. Postoperative DH (the distracted distance) had the greatest impact on the incidence of ASD. Excessive disc space distraction is a considerable risk factor for the development of radiographic ASD.

  9. Loading effects of anterior cervical spine fusion on adjacent segments

    Directory of Open Access Journals (Sweden)

    Chien-Shiung Wang

    2012-11-01

    Full Text Available Adjacent segment degeneration typically follows anterior cervical spine fusion. However, the primary cause of adjacent segment degeneration remains unknown. Therefore, in order to identify the loading effects that cause adjacent segment degeneration, this study examined the loading effects to superior segments adjacent to fused bone following anterior cervical spine fusion. The C3–C6 cervical spine segments of 12 sheep were examined. Specimens were divided into the following groups: intact spine (group 1; and C5–C6 segments that were fused via cage-instrumented plate fixation (group 2. Specimens were cycled between 20° flexion and 15° extension with a displacement control of 1°/second. The tested parameters included the range of motion (ROM of each segment, torque and strain on both the body and inferior articular process at the superior segments (C3–C4 adjacent to the fused bone, and the position of the neutral axis of stress at under 20° flexion and 15° extension. Under flexion and Group 2, torque, ROM, and strain on both the bodies and facets of superior segments adjacent to the fused bone were higher than those of Group 1. Under extension and Group 2, ROM for the fused segment was less than that of Group 1; torque, ROM, and stress on both the bodies and facets of superior segments adjacent to the fused bone were higher than those of Group 1. These analytical results indicate that the muscles and ligaments require greater force to achieve cervical motion than the intact spine following anterior cervical spine fusion. In addition, ROM and stress on the bodies and facets of the joint segments adjacent to the fused bone were significantly increased. Under flexion, the neutral axis of the stress on the adjacent segment moved backward, and the stress on the bodies of the segments adjacent to the fused bone increased. These comparative results indicate that increased stress on the adjacent segments is caused by stress-shielding effects

  10. 腰椎融合内固定对邻近节段退变的影响★%Effect of lumbar fusion and fixation on adjacent segment degeneration

    Institute of Scientific and Technical Information of China (English)

    龚冰南; 徐皓; 陈建梅; 李金泉

    2013-01-01

    BACKGROUND: With the mature of the spinal surgery and the development of fixation instrument, spine fusion and fixation has become the main method for the treatment of spine diseases, but the long-term adjacent segment degeneration is more and more serious. OBJECTIVE: To retrospectively analyze the risk factors of adjacent segment degeneration after spinal fixation, which can help to improve spine fixation and reduce the long-term complications. METHODS: A computer-based search was performed on VIP database and PubMed database for the articles on the adjacent segment degeneration after spine fusion and fixation published from January 2005 to December 2012, the key words were “spine fusion, adjacent segment degeneration, unilateral single cage” in Chinese and English. Al articles were selected firstly, and those related to adjacent segment degeneration after spine fusion were col ected. Randomized control ed trials were included and the nonrandomized control ed trials were excluded. The duplicated investigations were eliminated. The articles explored the adjacent segment degeneration after spine fusion mainly dependent on the surgical method, fusion mode and damage of adjacent segment. RESULTS AND CONCLUSION: A total of 27 articles were coincident with the inclusion criteria. From the articles, we find that the fusion number, way, position and the damage to the adjacent segment were the main reasons for adjacent segment degeneration. The total disc replacement and unilateral single cage play important role in preventing and delaying the adjacent segment degeneration. The influence of the fixation materials and surgical way should be considered before fusion, in order to avoid and reduce the occurrence of adjacent segment degeneration.%  背景:随着脊柱手术方法的成熟及内固定器械的发展,脊柱内固定融合术已成为许多脊柱疾患的主要治疗方法,但远期出现的邻近节段退变的问题也越来越突

  11. 颈椎人工椎间盘置换后对相邻节段退变的影响%Effect of cervical disc arthroplasty on adjacent segment degeneration

    Institute of Scientific and Technical Information of China (English)

    孙宇; 赵衍斌; 周非非; 张凤山; 潘胜发; 周方; 刘忠军

    2011-01-01

    Objective:To investigate the adjacent segment degeneration after single level cervical disc arthroplasty. Method : Patients received single level cervical arthroplasty in our institute were reviewed retrospectively. Up to October 2010,a total of 80 patients gained at least 20 months' follow-up.There were 8 cases of C3/4,15 C4/5,49 C5/6 and 8 C6/7.41 patents received Bryan Disc cervical prosthesis and 39 received ProDisc-C prosthesis. Adjacent segment degeneration was evaluated on X-ray and magnetic resonance imaging (MRI) at preoperative and final follow-up.X-ray based adjacent segment degeneration included the presence of aoy of the following parameters:narrowing of disc space>10%,new anterior or/and extended osteophyte formation,calcification of anterior longitudinal ligament. Cervical disc degeneration was evaluated according to Miyazaki's grading system based on T2-weighted MRI.Result:The mean follow-up period was 38 months (range,20-64 months).Of 160 segments at final follow-up,8 distal adjacent segments were excluded due to unavailability of X-ray,adjacent segment degeneration was observed in 21 of 152 segments(13.8%) based on X-ray findings.The rate of adjacent segment degeneration for Bryan disc group was 10.0%,which was lower than that of ProDisc-C group (18.1%).47 patients gained MRI follow-up,and adjacent segment degeneration was observed in 14 of 94 segments (14.9%).The rate of MRI-based adjacent segment degeneration for Bryan Disc group was 12.5%,which was also lower than that of ProDisc-C group (22.7%).No adjacent segment disease developed at final follow-up. Conclusion:Less than 15% cases develop adjacent segment degeneration 38 months after cervical disc arthroplasty,and the effect may vary between different prosthesis.%目的:观察单节段颈椎人工椎间盘置换术后相邻节段退变情况.方法:截止到2010年10月在我院行单节段颈椎人工椎间盘置换术后随访20个月以上且资料完整、既

  12. Analysis of adjacent segment degeneration of patients with anterior cervical discectomy and fusion%颈椎前路减压植骨融合术后邻近节段退变情况分析

    Institute of Scientific and Technical Information of China (English)

    邓志龙; 张晓星; 王令; 李邦春

    2011-01-01

    目的 分析颈椎前路减压植骨融合术后融合椎体邻近节段退变的影响因素.方法 选取250例行颈椎前路减压植骨融合内固定手术治疗的患者作为研究对象,观察术后邻近节段退变的发生情况,对退变患者组与无退变患者组各项观察指标进行统计学比较.结果 共72例(75个节段)(28.8%)发生术后邻近节段退变,椎间盘退变程度按评分,1分48例,2分21例,3分3例;退变组术前D值(1.26±1.30)mm、术后D值(3.76±3.10)mm,明显小于无退变组的(1.90±1.30)mm与(5.85±3.04)mm(P0.05).结论 颈椎前路减压植骨融合术后融合椎体邻近节段退变发生率较高;颈椎前凸程度较小、且手术对颈椎前凸程度改善较小是导致邻近节段退变发生的重要影响因素.%Objective To analyze the influeneing factors of adjacent segment degeneration of patients with anterior cervical discectolny and fusion. Methods Totally 250 cases of anterior cervical discectolny and fusion were selected for study. The incidence of adjacent segment degeneration was observed and the indexes of degeneration group and non-degeneration group were compared statistically. Results There were 72 cases (75 segment) of adjacent segment degeneration( 28.8% ) ,including 48 cases of degradation score of 1, 21 cases of degradation score of 2,3 cases of degradation score of 3. The preoperative D value of degradation group was ( 1.26 ± 1.30 ) mm, while ( 3.76 + 3.10) mm after operation, indicating significantly lower than that of non-degradation group ( P < 0.05 ).The postoperative D value of degradation group increased by ( 2.5 + 3.21 ) mm,notably lower than that of non-degradation group (3.95 ± 3.13) mm ( P < 0.05 ) . The age, gender distribution, JOA score and Cobb' s angle of the two groups had no statistical difference( P < 0.05). Conclusion The incident rate of adjacent segment degeneration in patients with anterior cervical diseectolny and fusion is high. The small degree of

  13. Adjacent Segment Pathology after Anterior Cervical Fusion.

    Science.gov (United States)

    Chung, Jae Yoon; Park, Jong-Beom; Seo, Hyoung-Yeon; Kim, Sung Kyu

    2016-06-01

    Anterior cervical fusion has become a standard of care for numerous pathologic conditions of the cervical spine. However, subsequent development of clinically significant disc disease at levels adjacent to fused discs is a serious long-term complication of this procedure. As more patients live longer after surgery, it is foreseeable that adjacent segment pathology (ASP) will develop in increasing numbers of patients. Also, ASP has been studied more intensively with the recent popularity of motion preservation technologies like total disc arthroplasty. The true nature and scope of ASP remains poorly understood. The etiology of ASP is most likely multifactorial. Various factors including altered biomechanical stresses, surgical disruption of soft tissue and the natural history of cervical disc disease contribute to the development of ASP. General factors associated with disc degeneration including gender, age, smoking and sports may play a role in the development of ASP. Postoperative sagittal alignment and type of surgery are also considered potential causes of ASP. Therefore, a spine surgeon must be particularly careful to avoid unnecessary disruption of the musculoligamentous structures, reduced risk of direct injury to the disc during dissection and maintain a safe margin between the plate edge and adjacent vertebrae during anterior cervical fusion.

  14. Clinical observation and analysis of adjacent segment degeneration after anterior cervical fusion%颈椎前路融合术后相邻节段退变的临床观察与分析

    Institute of Scientific and Technical Information of China (English)

    王义生; 邓俊森

    2012-01-01

    [Objective] To study whether the anterior cervical fusion inevitably lead to the adjacent segment degeneration (ASD) . [Methods] From 1986.1 to 1999. 12, a total of 346 patients with cervical degenerative disease underwent the surgery of enlarged decompression with circular saw and auto iliac bone grafting. Among them there were 1 segment in 55 patients, 2 segments in 223 patients and 3 segments in 68 patients. The two motion segments adjacent to the fused segment and interval from the fused segment were evaluated respectively for imaging changes and divided the results into groups for statistical test. [Results] The patients were followed up for 13. 5 (4.1 ~ 18) years on average. Total 156 cases (45. 1% ) had obvious adjacent segment degeneration, 23 cases (6. 6% ) had obvious interval segment degeneration. The interval segment degeneration was less than that of adjacent segment degeneration, and the comparative differences had statistically significance (P 0.05 ) . [ Conclusion] The anterior cervical fusion accelerated the occurrence of ASD. The incidence of cephalic adjacent segment ASD was higher than that of tail side adjacent segments. The incidences of postoperative ASD in single segment and several segment fusion have no significant differences.%[目的]研究颈椎前路融合术是否必然导致邻近节段退变(adjacent segment degeneration,ASD).[方法]1986~1999年,共346例采用“环锯法前路扩大脊髓减压+椎体间植骨内固定术”治疗颈椎退变性疾病,其中,1个间隙55例,2个间隙223例,3个间隙68例.分别评定融合节段头、尾侧相邻间隙及间隔间隙的影像学表现,对结果分组进行统计学检验.[结果]术后随访13.5 (4.1 ~18)年,发生邻近节段明显退变的156例(45.1%),间隔节段明显退变的23例(6.6%).间隔节段退变明显少于邻近节段退变,两者比较差异有统计学意义(P<0.05).单纯头侧邻近节段发生ASD 84例,单纯尾侧邻近节段发生ASD 27例,头

  15. Artificial cervical disc replacement: range of motion of replacement segment and degeneration of adjacent segments%人工颈椎间盘置换:置换节段活动度及相邻节段退变分析

    Institute of Scientific and Technical Information of China (English)

    陈渲宇; 初冬; 伍骥; 郑超; 黄蓉蓉; 崔玉明; 尚咏; 范恒华; 虞攀峰; 赵旭红

    2015-01-01

    BACKGROUND:In recent years,artificial cervical disc replacement surgery as a new method for the treatment of cervical disease has gradualy been accepted and understood,but relevant complications have gradualy attracted attention.OBJECTIVE:To investigate the clinical outcomes of artificial cervical disc replacement in the treatment of cervical disease and the range of motion of the replacement segment.METHODS: A total of 25 patients with artificial cervical disc replacement in the treatment of cervical spondylosis,who were treated in the Department of Orthopedics,Air Force General Hospital of Chinese PLA from August 2006 to April 2012,were enroled in this study,including 15 males and 10 females,aged 31-76 years,averagely 51.04 years.There were 6 cases of double segments and 19 cases of single segment.They were folowed up for 24 to 93 months.Clinical results were assessed using the Japanese Orthopaedic Association score,cervical dysfunction index and pain visual analog scale scores.Imaging was used to observe range of motion,cervical curvature,heterotopic ossification,and degeneration of adjacent segments.RESULTS AND CONCLUSION:Neurological function in al patients was improved to different degrees.One case suffered from mild heterotopic ossification,but no clinical symptoms were found.No significant difference in range of motion of surgical segment,and range of motion of upper and lower adjacent segments was detected between pre-replacement and final folow-up results (P>0.05).No significant difference in range of motion of C2-C7 was found between pre-replacement and final folow-up results (P>0.05).Japanese Orthopaedic Association score,cervical dysfunction index and pain visual analog scale scores were significantly improved during final folow-up compared with pre-replacement (P<0.05).These results indicated that artificial cervical disc replacement in the treatment of cervical disease can achieve better clinical efficacy,can keep the range of motion of

  16. Adjacent segment degeneration following spinal fusion%脊柱融合术后相邻节段退变的研究进展

    Institute of Scientific and Technical Information of China (English)

    万军; 胡炜; 夏英鹏; 张学利

    2008-01-01

    随着手术方法的日趋成熟和脊柱内固定器械的日新月异,脊柱融合术的成功率有了明显提高。同时由于脊柱融合术改变了脊柱正常的生物力学环境,各节段所承受应力进行重新分配,融合节段上下相邻椎间盘的应力愈加集中,邻近节段退行性变(adjacent segment degeneration,ASD)的问题则变得更加突出,引起人们越来越多的关注。笔者就近年脊柱融合术后ASD的研究现状及进展做一综述。

  17. 经前路颈椎椎体次全切除钛网置入融合后相邻节段的退变%Adjacent segment degeneration after anterior cervical corpectomy and fusion

    Institute of Scientific and Technical Information of China (English)

    翟鹏飞; 刘伟; 孙志明; 张学利

    2016-01-01

    BACKGROUND:In recent years, the researchers have studied the adjacent segment degeneration after cervical fusion. Several studies concerned the adjacent segment degeneration after anterior cervical corpectomy and fusion. OBJECTIVE:To evaluate the correlative factors of adjacent segment degeneration after anterior cervical corpectomy and fusion. METHODS:122 patients were included in the study from 126 patients who underwent anterior cervical corpectomy and fusion that operated by the same treatment team and involved a single vertebral body and the two plates between February 2009 and February 2012. The final fol ow-up period was 3 years. According to the degeneration progress of adjacent segment degeneration, these patients were divided into non-progression group and progression group. The gender, age, preoperative adjacent segment degeneration, cervical range of motion, upper and lower vertebral range of motion, surgical segment, titanium mesh subsidence, plate-to-disc distance, and cervical curvature index were compared between two groups. Logistic regression analysis was applied to analyze the correlative factors of adjacent segment degeneration. RESULTS AND CONCLUSION:(1) There were significant differences in preoperative adjacent segment degeneration, postoperative cervical range of motion, postoperative upper and lower vertebral range of motion, and postoperative cervical curvature index (P  目的:探讨经前路椎体次全切除钛网椎间置入融合后相邻节段退变的相关因素。  方法:纳入2009年2月至2012年2月行经前路椎体次全切除钛网椎间置入融合的患者共126例,其中资料完整的122例纳入研究。均由同一治疗组完成,且手术均涉及单个椎体及2个间盘。终末随访期为3年。根据术前及术后相邻节段退变程度,分为非相邻节段退变进展组和相邻节段退变进展组,比较2组患者的性别、年龄、术前相邻节段退变、颈椎活动度、术椎

  18. ADJACENT SEGMENT DEGENERATION AFTER CERVICAL ARTIFICIAL DISC REPLACEMENT AT EARLY MID-TERM FOLLOW-UP%人工颈椎间盘置换术后邻近节段退变情况的早中期随访

    Institute of Scientific and Technical Information of China (English)

    刘雅普; 夏虹; 艾福志; 石林; 隋文渊

    2012-01-01

    Objective To study the effectiveness of artificial disc replacement for cervical diseases and the adjacent segment degeneration. Methods Between January 2008 and October 2010, 39 cases of cervical spondylosis underwent cervical disc replacement. Of them, there were 20 males and 19 females with an average age of 45.7 years (range, 32-60 years) and an average disease duration of 30 months (range, 1 month to 10 years), including 26 cases of cervical myelopathy, 11 cases of nerve root cervical spondylosis, and 2 cases of mixed cervical spondylosis. Single level disc lesion was observed in 27 cases while bi-level lesion in 12 cases. Prestige disc prosthesis was used in 9 patients, Prodisc-C prosthesis in 4 patients, and Discover disc prosthesis in 26 patients. The neurological functional recovery was assessed after operation by Japanese Orthopaedic Association (JOA) score. The range of motion of replaced segment and adjacent segments was measured (Cobb angle), and Kellgren's X-ray assessment was used to evaluate the degree of adjacent segment degeneration. Results The operation was successfully performed in all cases, with primary healing of all the incisions. All patients were followed up from 12 to 36 months with an average of 23.1 months. JOA score was significantly improved at last follow-up when compared with preoperative score (P 0.05). According to the Kellgren's X-ray assessment, degeneration of the adjacent segments occurred in 5 cases at last follow-up, including 3 cases of degeneration from grade 0 to grade 1 or 2, 1 from grade 1 to grade 2, and 1 from grade 2 to grade 3, with a degeneration rate of 12.8%, but no significant difference was found in degeneration degree when compared with preoperative value (X2=1.793, P=0.406). No degeneration of adjacent segments occurred in 32 patients at 15 months after operation. Conclusion Artificial disc replacement has a good effectiveness in treating cervical spondylosis, which can maintain the range of motion of the

  19. Adjacent segment degeneration after anterior cervical discectomy and fusion follow-up%颈椎前路融合术后邻近节段退变情况的研究

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

      目的通过观察分析前路颈椎间盘切除融合术(anterior cervical discectomy and fusion,ACDF)术后随访患者的影像学资料,探讨邻近节段病变的发生时间和发生率。方法分析2008年以来本科收治的94例施行 ACDF 手术并获得完整随访的患者,其中男性51例,女性43例;年龄28~70岁,平均50.5岁。融合节段:单节段42例,上节段30例,三节段22例。术前均常规行颈椎正、侧位 X 线、MRI 检查。术后评定患者神经功能恢复情况,根据 Kellgren 分级标准对临近节段颈椎间盘退变情况进行 X 线评价。结果94例患者随访时间12~45个月,平均随访时间为29.1月。术后患者神经功能改善明显,JOA 评分较术前提高5.8,改善率为64.3%,有效率为100%。临近节段颈椎间盘退变情况的 X 线评估显示,有19例发生临近节段的退变,其中12例有轻度退变表现,7例出现较严重退变表现,邻近节段退变发生率为20.2%。退变发生时间为术后5~40个月,平均为18.7±4.79个月。结论 ACDF 治疗颈椎间盘退行性疾病有良好的疗效,术后邻近节段发生退变时间为18.7±4.79月,随访29.1个月邻近节段退变发生率为20.2%。%Objective To study the clinical efficacy of anterior cervical discectomy and fusion(ACDF) for cervical spondylosis , also the rate and occurrence time of adjacent segment degeneration.Methods 94 cases (male: 51, female: 43, average age: 50.5, ranging from 28 to 70)of cervical spondylosis admitted to our department since 2008 were analyzed in this study.42 patients were performed with single-level ACDF, 30 patients with double-level ACDF,and 22 patients with three-level ACDF. The cervical anterior-posterior and lateral X-ray and MRI examination were performed before the operation.Neurological functional recovery was assessed after operation. X -ray was used to evaluate the degree of adjacent segment degeneration according to

  20. Influence of posterior lumbar interbody fusion to adjacent segment degeneration%后路腰椎椎间融合术对邻近节段退变的影响

    Institute of Scientific and Technical Information of China (English)

    管俊杰; 石志才

    2011-01-01

    Objective Lumbar interbody fusion induces the change of lumbar normal biomechanical environment. The adjacent segments have the character of stress concentration. This study aimed to observe the lurnhar adjacent segment degeneration(ASD) after posterior lumbar interbody fusion(PLIF). Methods From 2002 to 2006, 60 patients (38 males and 22 females, aged 25-77 years old, with a mean value of 46 years old) with symptomatic degenerative diseases underwent PLIF The incidence of ASD, position and radiographic characteristics were studied. The relation between “floating fusion” and ASD were compared, and the relation of fusion range and ASD was also studied. Results All patients were followed up for 2.0-6.5 years ( mean 4.5 years). Eleven patients ( 18.3% ) were found to have radiographic characteristics of ASD. Nine of them had ASD at cranial segments, the other 2 at caudal segnents. The difference between using “floating fusion” or not in the risk of ASD was not statistically significant. The dffference between single-level fusion and double-level fusion was not statisticaly significant, either. Conclusion After PLIF, stress concentration of adjacent segments was abnormal ,which increases the incidence of ASD. The cranial segment has a higher degeneration risk than the caudal segment.%目的 腰椎融合术改变了腰椎的生物力学环境,使邻近节段应力集中,本研究就后路腰椎椎间融合术(posterior lumbar interbody fusion,PLIF)对邻近节段退变(adjacent segment degeneration,ASD)的影响进行探讨.方法 2002~2006年,采用PLIF治疗腰椎退行性疾病患者60例,其中男38例,女22例;年龄为25~77岁,平均46岁.观察其术后ASD的发生率、发生部位及影像学特点,对是否"悬浮固定"及内固定融合范围引发ASD的风险进行对比.结果 所有患者随访2.0~6.5年,平均4.5年.影像学有退变表现者11例(18.3%),其中9例发生在内固定头侧邻近节段,2例发生在尾侧邻近节段.是

  1. 脊柱融合术后邻近节段退变再手术治疗的临床研究%Clinical study on the second surgical procedure of adjacent segment degeneration after the first time spinal fusion

    Institute of Scientific and Technical Information of China (English)

    曾云; 熊敏; 陈森; 余化龙; 何宁; 王志勇; 刘志刚; 韩珩

    2011-01-01

    Objective To discuss the effectiveness of the second surgical procedure of adjacent segment degeneration after the first spinal fusion.Method 35 patients who had been performed spinal fusion in our hospital or had symptoms recurred or aggravated after 12 ~ 114 (42 ±35) months of the prior surgery were enrolled in this study.A second surgery was performed and intraoperative the intradiscal pressure of adjacent segments of degeneration and normal segments was measured.The VAS score systems were compared among prior surgery,3 months later and 2 years after the second surgery.Result The intradiscal pressure of adjacent segments after the cervical vertebra and lumbar vertebra fusion were [ (15 ± 4.6)cmH2O,(23 ±5.2)cmH2O],much higher than normal segments [ (3 ±2.3)cmH2O,(8 ±4.1)cmH2O](P <0.01).The VAS score systems of 3 months later and 2 years after the second surgery were [ (2.9 ±0.7),(2.0 ± 0.6) ],which were dramatically lower than the prior (7.8 ± 1.2) (P < 0.01).In 12 ~ 46(31 ± 12) months of follow-up after the second procedure,X-ray and MRI showed that fusion segments reached nearly bone fusion,well decompressed and without nerve compression or other complications.Conclusion If recurrence of symptoms after spinal fusion were caused by adjacent segment degeneration,reoperation would guarantee good clinical outcome.%目的 探讨脊柱融合术后邻近节段退变再手术治疗的疗效.方法 85例既往在本院行脊柱融合术的患者,术后12~114(42±35)个月症状复发或加重.对所有患者进行再手术治疗及术中测量邻近退变节段与正常节段椎间盘内压,比较再次手术前、术后3月及2年的视觉模拟评分.结果 颈椎、腰椎融合术后邻近退变节段的椎间盘内压[(15±4.6)cmH2O、(23±5.2)cmH2O]显著高于正常节段[(3±2.3)cmH2O、(8±4.1)cmH2O](P<0.01).术后3个月、2年视觉模拟评分(2.9±0.7)、(2.0±0.6)较再次手术前(7.8±1.2)明显降低(P<0.01).再手术后经12~46

  2. 兔脊柱融合术后邻近节段退变的组织学观察%THE HISTOLOGICAL OBSERVATION OF ADJACENT SEGMENT DEGENERATION IN RABBITS AFTER SPINAL FUSION

    Institute of Scientific and Technical Information of China (English)

    贾海生; 吉茹; 吕慧成; 杨学军

    2014-01-01

    endplate of adjacent segment were easier to degenerate after spinal fusion,and adjacent segment above the fusion level was easier to degenerate than that below the fusion level.

  3. Clinical Analysis on the Impact of Lumbar Fixation and Intervertebral Fusion to the Adjacent Segment Degeneration%腰椎融合内固定术融合节段对相邻节段退变影响的临床分析

    Institute of Scientific and Technical Information of China (English)

    郭朝阳; 李明恒; 陈荣春

    2014-01-01

    Objective:To investigate the relationship between postoperative degeneration of adjacent segment and fusion segment number of lumbar vertebra.Method:A retrospective analysis of 69 patients were made,who underwent pedicle screws fixation and posterior lumbar intervertebral fusion for lumbar degenerative disease form June 2002 to May 2008. According to the number of lumbar fusion segments,those patients were divided into three groups. The group A was single segment fusion(24 cases);the group B was double segments fusion(26 cases)and the group C was multi-segments fusion( ≥ 3 segments,19 cases). The intervertebral height,displacement of slippage of the adjacent segment,lumbar lordosis angle and lumbosacral joint angle was measured on the X-ray preoperative and postoperative at the last follow-up. The incidence rate of adjacent segment degeneration was assessed by imaging evaluation criteria,and the relationship between adjacent segment degeneration and the number of fusion segment was analyzed.Result:The average follow-up period was 31.6 months(18-72 months).All patients had no neurological deterioration. At the last follow-up,there were 2 patients in the group A(8.3%),4 patients in the group B(15.4%)and 4 patients in group C(21.1%)occurred adjacent segment degeneration. There was no significant difference between group A and group B at the incidence of the adjacent segment degeneration(P>0.05). Compared with the group A and B,the group C had significant differences at the incidence of the adjacent segment degeneration(P0.05);C组相邻节段退变发生率与其他两组比较差异有统计学意义(P<0.05)。结论:腰椎后路融合内固定术会增加相邻节段退变,融合固定节段越多,相邻节段退变发生率越高。

  4. Adjacent segment degeneration after posterior lumbar fusion: a five-year follow-up%腰椎后路固定融合术后邻近节段退变的中期随访研究

    Institute of Scientific and Technical Information of China (English)

    陈文钧; 许耀; 许桦; 马晓生; 姜建元

    2011-01-01

    Objective To observe the degenerative changes of the discs adjacent to fixed lumber segment in patients undergoing posterior lumbar fusion 5 years ago by radiologic records, and to investigate the impact of these changes and their causes. Methods A total of 33 patients who underwent L4/L5 or L4/L5/S1 posterior lumbar fusion during 1999 to 2003 were enrolled to investigate the degenerative changes of the discs adjacent to fixed lumber segment ( L3/L4 or L4/S5) through their X-ray film and/or MRI. Intervertebral disc heights were measured before and after surgery. The patients were divided into 2 groups based on the fusion segment. Clinical status was evaluated by the recovery rate of the Japanese Orthopedic Association (JOA) score. Results Degeneration of the discs adjacent to fixed lumber segment was observed in 54.5% of subjects (18/ 33). However, no significant correlation was seen between postoperative disc narrowing and JOA score. Conclusion Degeneration of the discs adjacent to fixed lumber segment is quite common in the patients after posterior lumbar fusion. But there is no evidence that the degeneration has a correlation with clinical outcome of posterior lumbar fusion.%目的 随访观察腰椎后路融合内固定术后>5年邻近节段椎间盘退行性变的程度,讨论其影响程度和因素.方法 随访1999~2003年行腰椎后路融合术(L4/L5/S1、L5/S1)的患者33例,通过X线检查及部分病例的MRI检查,观察腰椎固定融合术后上方邻近节段(L3/L4、L4/S5)椎间盘退行性变的发生率和程度.结果 腰椎固定融合术后邻近节段椎间盘退行性变的发生率为54.5% (18/33),但邻近节段椎间隙高度降低和日本骨科学会(Japanese Orthopae-dic Association,JOA)评分之间没有明显关联.结论 腰椎融合术后邻近节段椎间盘发生退行性变的比例较高,但退变和临床疗效间并没有明显联系.

  5. 腰椎融合术后相邻节段退变的相关因素分析%Correlative factors for adjacent segment degeneration after lumbar spinal fusion

    Institute of Scientific and Technical Information of China (English)

    黄觅; 于淼; 刘晓光; 姜亮; 韦峰; 吴奉良; 刘忠军

    2014-01-01

    Objectives: To explore risk factors associating with adjacent segmental degenerations after lumbar fusion surgery. Methods: A retrospective analysis was performed on 109 cases of lumbar stenosis undergoing lumbar posterior decompression, pedicle screw fixation and fusion in orthopedic department of Peking Univer-sity Third Hospital from January 2009 to January 2011. These cases included 39 males and 70 females with ages ranging from 24 to 79 years(average, 54 years). All of them were followed up by a 2- to 4-year(aver-age, 3.4 years) outpatient questionnaire. Measurement included peroperative angles of fusion segment (FA), proximal and distal adjacent angles of fusion segments(PA, DA), lumbar lordosis(LL), sacral slope(SS), pelvic incidence(PI) in pre-operation, and slip distance(SD) between fusion and non-fusion segments. Adjacent seg-ment rdiograpfic degeneration was defined as adjacent segmental slip of 3mm or more on standing X-ray at post-operative 24 months. All patients were categorized into degenerative group(group A) and non-degenerative group(group B). Gender, age, bone mineral density, number of fusion segments were also recorded. The com-parative results between two groups were analyzed by t-test and χ2 -test. Risk factors of adjacent segment radiographic degeneration were analyzed by using Logistic regression. Results: There were 18 cases(16.5%) in group A and 91 cases(83.5%) in group B developing ASD, and all ASD occurred at proximal adjacent seg-ments. Preoperative results were as follows: LL for group A and B was 29.8°±12.5° and 32.4°±11.2°; SS for group A and B was 31.5°±12.1° and 37.4°±13.4°; FA for group A and B was 18.3°±9.0° and 14.8°±10.5°;PA for group A and B was 6.8° ±3.2° and 7.2° ±5.2° , which all showed significant differences between two groups(P0.05). Logistic regression analysis showed significant correlation with PI and incidence of ASD(P0.05). Conclusions: Of the risk factors inducing ASD, low PI may be one

  6. 单侧椎弓根螺钉置入并椎间融合对邻近椎间盘节段退变的影响%Unilateral pedicle screw fixation with lumbar interbody infusion for adjacent segment degeneration

    Institute of Scientific and Technical Information of China (English)

    邵高海; 焦春燕; 余雨; 钟斌; 李波

    2011-01-01

    背景:坚强内固定和良好融合存在严重缺陷和不足.目前还未见临床应用单侧椎弓根螺钉固定结合椎间cage植骨融合治疗腰椎退变性疾病对邻近节段退变影响的相关报道.目的:回顾分析单侧椎弓根螺钉固定结合椎间cage植骨融合治疗部分腰椎退变性疾病后对固定融合邻近上下节段退变的影响.方法:2006-03/2009-12对收治的部分腰椎管狭窄症、腰椎失稳及腰椎间盘脱出症患者22例,进行了单侧椎弓根螺钉固定加椎间cage植骨融合,术中不显露对侧.在固定融合后3,6,12,20个月及取出内固定钉棒后3,6个月,随访X射线片及MRI.针对X射线片运用角平分线法测量固定融合邻近上位椎间隙高度变化,MRI测量椎间盘髓核退变情况.结果与结论:所有病例获得随访,患者椎管狭窄症状及神经根性症状消失,并且在随访期间内没有新的临床症状出现.固定融合前、固定融合后3,6,12,20个月邻近节段上位椎间隙高度分别为(7.420±0.035 4),(7.426 6±0.036 9),(7.453 3±0.036 9),(7.516 6±0.036 9),(7.430 8±0.036 9) mm,结果表明,腰椎单侧固定融合后邻近节段椎间隙高度无明显变化(P > 0.05).MRI测量结果显示,固定融合邻近上位椎间盘髓核信号在T2加权像无明显退变.提示单侧椎弓根螺钉固定结合椎间融合治疗部分腰椎退变性疾病能有效预防固定融合邻近上下节段退变.%BACKGROUND: There are no reports add ressing effects of unilateral pedicle screw plus cage internal fixation on adjacent segment degeneration in the treatment of lumbar degenerative disease.OBJECTIVE: To review the effects of unilateral pedicle screw plus cage internal fixation on adjacent segment degeneration in the treatment of lumbar degenerative disease.METHODS: From 2006 to 2009, 22 patients with partial lumbar spinal stenosis, lumbar instability, and lumbar intervertebral disc herniation received unilateral pedicle screw plus cage

  7. 腰椎单节段固定融合术后上位相邻节段退变及其与临床疗效的关系%Analysis of cranial adjacent segment degeneration after single-segment instrumented fusion: clinical results and risk factors

    Institute of Scientific and Technical Information of China (English)

    陈柏龄; 魏富鑫; 植山和正; 三户明夫; 刘少喻; 廖鹰扬

    2011-01-01

    目的:探讨腰椎单节段固定融合术后上位相邻节段退变及其与临床效果的关系,分析退变的相关因素.方法:回顾性分析2004年10月~2009年5月采用后路单节段椎弓根螺钉固定并椎体问cage植骨融合术治疗的49例L4/5退变性失稳患者,男22例,女27例,年龄28~72岁(平均53.4岁).所有患者术前均行骨密度检测.存X线片卜测量固定节段及其上位相邻节段椎间盘高度、椎间隙动态角度变化、椎体滑移距离以及固定节段和腰椎前凸角、腰骶关节角,并通过JOA评分及腰功能障碍指数(ODI)评价临床效果.根据末次随访时上位相邻节段有无影像学退变,分为退变组与非退变组,比较两组间临床效果及影像学测量结果.结果:随访时间为13~52个月,平均为29.3个月,所有患者术后均无神经损害加重症状.末次随访时11例患者(22%)出现上位相邻节段影像学退变.两组患者手术时的平均年龄有显著性差异(P0.05);末次随访时L3/4椎体问滑移距离、L3/4椎间盘高度以及椎间隙动态成角变化值均存在显著性差异(P0.05).患者年龄与末次随访时固定上位相邻节段椎间盘高度、椎间隙动态成角、椎体间滑移距离变化值存在正相关性,相关系数分别为0.353、0.521、0.472,余测量指标与固定上位相邻节段影像学指标变化均无显著相关性.结论:单节段腰椎固定融合术后上位相邻节段影像学退变与临床效果之间无显著相关性.此退变与患者年龄相关,而与骨密度和术前腰椎影像学测量指标无显著相关性.%Objective:To investigate the relationship between degeneration of cranial adjacent segment after single-segment instrumented fusion and its clinical results,and analyze the risk factors of degeneration of cranial adjacent segment.Method:A retrospective study of 49 patients who underwent pedicle screws fixation and posterior lumbar interbody fusion(PLIF) at the L4/5 segment

  8. Wallis棘突间动态稳定系统在预防腰椎相邻节段退变中的作用%Wallis interspinous dynamic stabilization system in prevention of adjacent segment degeneration of involved lumbar vertebrae

    Institute of Scientific and Technical Information of China (English)

    苏斌; 伍骥; 郑超; 黄蓉蓉; 崔玉明; 张新合; 初冬; 虞攀峰

    2013-01-01

      背景:腰椎融合术一直被认为是治疗腰椎间盘退变性疾病的金标准。但有文献报道,腰椎融合术加速相邻节段的退变,因此提出了非融合技术。  目的:探讨棘突间动态稳定系统(interspinous dynamic stabilization system, IDSS)植入在预防相邻节段退变(adja-cent segment degeneration, ASD)中的作用。  方法:回顾性分析2007年7月至2010年10月应用Wallis棘突间动态稳定系统(WIDSS)治疗单纯L4-L5节段椎间盘源性腰痛(discogenic low back pain, DLBP)患者的临床资料。共33例患者,男13例,女20例;年龄30~63岁,平均(46.2±12.3)岁。临床疗效采用腰痛的视觉模糊评分(visual analogue scale, VAS)及Oswestry功能障碍指数(Oswestry disabili-ty index, ODI)进行评价。摄 X 线片测量病变节段以及相邻节段活动范围(range of motion, ROM)及椎间盘高度(disc height, DH)的变化。  结果:所有患者均获随访,随访时间18~52个月,平均32个月。腰痛VAS评分由术前的(7.8±1.4)分降至随访时的(2.5±1.6)分,ODI 由术前的(69.3±8.5)%减至随访时的(27.3±9.4)%,术前与随访时的 VAS、ODI 比较有统计学差异(P0.05)。  结论:WIDSS在有效治疗DLBP的同时,保留了手术节段的一定活动度,不增加邻近节段的活动度及退变发生率,对相邻节段的退变具有一定的保护作用。%Background: Lumbar spinal fusion has been recognized as the gold standard for treatment of disc degenerative disease, but it has been reported that lumbar spinal fusion can accelerate the degeneration of adjacent segments. So the lumbar non-fu-sion has been proposed. Objective: The purpose of the study is to investigate the effect of interspinous dynamic stabilization system (IDSS) in pre-vention of adjacent segment degeneration (ASD). Methods: The clinical data of 33 patients who were treated by Wallis IDSS for L4-L5

  9. Topping-off手术预防相邻节段退变加重的回顾性研究%The effect of Topping-off surgery on preventing adjacent segment degeneration, a retrospective study

    Institute of Scientific and Technical Information of China (English)

    刘海鹰; 周健; 王波; 王会民; 金朝晖; 朱震奇; 缪克难

    2012-01-01

    preventing adjacent segment degeneration when mild or moderate adjacent segment degeneration exists before surgery.Methods All the cases that received L5-S1 posterior lumbar interbody fusion(PLIF)+ L4-L5interspinous process(ISP)surgeries between April 2008 and March 2010(Topping-off group)were analyzed retrospectively.The cases received L5-S1 PLIF surgery and whose intervertebral disc degeneration using modified Pfirrmann's grading system were grade 4-6 were analyzed retrospectively at the same time(PLIFgroup).Both groups matched in gender,age,body mass index and Pfirrmann's grading of disc.All the patients were evaluated with visual analogue scale(VAS)and Japanese orthopaedic association(JOA)scores before the surgery and in the last follow-up.The X-ray films before and after surgery were measured.Results There were 25 patients in Topping-off group and 42 patients in PLIF group were included in the final analysis.The follow-up averaged 24.8 and 23.7 months.No symptomatic or radiological adjacent segment degeneration was observed.The average surgery time was(120 ± 24)min and(106 ± 21)min.There was no significant difference in the blood loss during surgery or post-operation drainage(P > 0.05).VAS and lumbar JOA score improved in both groups(P < 0.01).In the lateral view of lumbar spine,neither of anterior or posterior disk height was significantly changed(P > 0.05),segmental lordosis of L4-L5,total lordosis were all increased(Topping-off group:t =-2.30 and-2.24,P < 0.05 ; PLIF group:t =-2.76 and -1.83,P < 0.05).In the hyperextension and hyperflexion view,Topping-off group' s range of motion (ROM)and olisthesis in the L4-5 segment did not significantly change in flexion(P >0.05),but decreased in extension(t =5.83 and 4.92,P <0.01).In PLIF group,the ROM(t =-7.82 and-4.90,P <0.01)and olisthesis(t =-15.67 and-18.55,P < 0.01)both significantly increased in extension and flection.Conclusions Compared with single segmental PLIF surgery,Topping-off surgery can

  10. Risk Factors for the Development of Adjacent Segment Disease Following Anterior Cervical Arthrodesis

    OpenAIRE

    Ezgi Akar; Mehmet Ufuk Akmil; Merih İş

    2015-01-01

    Aim: The aim of this study was to clinically and radiologically evaluate the efficacy of anterior cervical discectomy and fusion (ACDF) in the treatment of adjacent level degeneration. Methods: We retrospectively evaluated 89 patients (55 females, 34 males) who underwent ACDF. Adjacent segment degeneration findings were evaluated by investigating new osteophyte formation, growth of existing osteophytes, ossification of the anterior longitudinal ligament, presence of inter...

  11. PRESENT CLINICAL RESEARCH SITUATION OF ADJACENT SEGMENT DEGENERATION AFTER LUMBAR SPINAL FUSION%腰椎融合术后邻近节段退变的临床研究现状

    Institute of Scientific and Technical Information of China (English)

    双峰; 侯树勋

    2013-01-01

    Objective To review the present clinical research situation of adjacent segment degeneration (ASD) after lumbar spinal fusion. Methods The recent literature concerning ASD in the concept, the incidence, the risk factors, and prevention was reviewed. Results The concept of ASD includes radiographic ASD and clinical ASD. The incidences of radiographic ASD and clinical ASD were 8%-100% and 5.2%-18.5%, respectively. The risk factors for ASD include both patient and surgical factors. Patient factors include age, gender, preoperative condition, and so on. Surgical factors include the length of the fusion, mode of fusion, internal fixator, sagittal balance, excessive distraction of disc space, and so on. It can prevent ASD to reduce the length of the fusion, to keep sagittal balance, and to use the non-fusion technology. Conclusion Many researches have proved that the incidence of ASD is increased after lumbar spinal fusion, and it can be reduced by the non-fusion technology. Non-fusion technology has obtained good short-term results. But the long-term results should be further observed because there are some complications.%目的 对腰椎融合术后出现邻近节段退变(adjacent segment degeneration,ASD)的临床研究现状进行综述. 方法 查阅近年关于腰椎融合术后出现ASD的概念、发生率、相关影响因素和预防等方面的文献,并进行综述. 结果 ASD的概念包括影像学ASD和临床症状ASD,腰椎融合术后影像学ASD发生率可达8%~100%,临床症状ASD发生率为5.2%~18.5%.ASD的发生与个体因素(年龄、性别、术前情况等)和手术因素(融合节段长短、融合术式、内固定使用、矢状面平衡、椎间隙过度撑开等)相关.术中减少融合节段、维持矢状面平衡以及非融合技术的应用可预防ASD的发生. 结论 腰椎融合术后ASD发生率增高.非融合技术的应用降低了ASD的发生率,取得了较好的近期临床效果,但也存在一些并发症,

  12. Risk Factors for the Development of Adjacent Segment Disease Following Anterior Cervical Arthrodesis

    Directory of Open Access Journals (Sweden)

    Ezgi Akar

    2015-06-01

    Full Text Available Aim: The aim of this study was to clinically and radiologically evaluate the efficacy of anterior cervical discectomy and fusion (ACDF in the treatment of adjacent level degeneration. Methods: We retrospectively evaluated 89 patients (55 females, 34 males who underwent ACDF. Adjacent segment degeneration findings were evaluated by investigating new osteophyte formation, growth of existing osteophytes, ossification of the anterior longitudinal ligament, presence of intervertebral disc space narrowing, sagittal alignment and range of motion (ROM using serial radiographs and magnetic resonance imaging. Results: The mean age of the 89 patients was 41.3 (24-76 years. The mean follow-up duration was 34.3 (12-64 months. Radiographic evidence of adjacent segment degeneration was observed in 12 patients (13.4%. Nine (75% patients had new complaints. Of the patients who had degenerative changes, 7 were (58% were male, 5 (42% were female; the mean age was 46 (30- 62 years. It was observed that the level of fusion and the number of fusion did not increase the adjacent segment degeneration. All of 12 patients were observed to have a non lordotic cervical spine and increased ROM. Conclusion: Development of degeneration at the level adjacent to region anterior cervical discectomy and fusion performed is higher compared to non-adjacent levels. The level of fusion and the number of fusion levels have no effect on the development of degeneration. (The Medical Bulletin of Haseki 2015; 53:120-3

  13. 颈椎前路融合致邻近节段椎间盘退变的原因探讨%Causes of adjacent segments disc degeneration caused by anterior cervical fusion

    Institute of Scientific and Technical Information of China (English)

    张克非; 刘伟; 于长水; 袁绍辉; 潘琦

    2011-01-01

    目的 探讨颈椎前路融合后邻近节段椎间盘退变的原因及其防治办法.方法 对实施颈椎前路融合术的126例颈椎间盘突出症患者进行回顾性分析,归纳可能导致颈椎前路融合术后临近椎间盘退变突出的原因.结果 随访时间最短10个月,最长10年,平均7.8年.37例颈椎间盘突出症患者发生临近节段椎间盘退变加重,其中7例患者再次手术.结论 颈椎前路融合后邻近节段椎间盘退变的原因可能为临近节段原有退变加重,椎间融合后生物力学改变,临近节段应力集中.%To investigate the causes of the adjacent intervertebral disc degeneration after anterior decompression and interbody fusion of C-spine and search for the way of prevention.Methods A retrospective study was given to 126 patients who underwent an anterior decompression and interbody fusion of C-spine, the causes of the adjacent intervertebral disc degeneration after anterior decompression and interbody fusion of C-spine were analyzed. Results The follow-up time was from 10 months to 10 years, average 7.8 years. Thirty-seven patients occurred the aggravation of adjacent intervertebral discs degeneration, in which 7 patients underwent reoperation. Conclusion The possible causes of the adjacent intervertebral disc degeneration after anterior decompression and interbody fusion of C-spine is that the aggravation of original degeneration of adjacent intervertebral disc, the alteration of biomechanics after anterior decompression and interbody fusion of C-spine induces the stress concentration of the adjacent intervertebral disc.

  14. Adjacent segment disc degeneration after lumbar interbody fusion:a systematic review%腰椎融合术后发生邻近节段椎间盘退变的系统评价

    Institute of Scientific and Technical Information of China (English)

    郝俊龙; 陈永刚; 夏亚一; 汪玉良; 王栓科; 汪静; 王翠芳; 耿彬

    2011-01-01

    [ Objective] To assess the efficacy and safety of bone morphogenetic protein for fractures. [ Methods] We searched the Cochrane Central Register of Controlled Trials (CENTRAL) ( Issue 3, 2010) , MEDLINE, EMBASE, CBM,CNKI, VIP, Wanfang database, etc. from their inception to June 2010. Some relevant journals were handsearched as well. Two reviewers independently evaluated the quality of included studies and extracted the data. Meta - analysis was performed by RevMan 5.0 software. [ Results ] Four trials involving 451 patients were included. Meta analysis showed that as for functional training, lumbar fusion increased risk of adjacent segment disc degeneration (ASD) . The incidence of ASD after lumbar laminectomy is higher than non - laminectomy. The existence of ASD preoperative increased risk of postoperative ASD. The incidence of ASD had no relation with internal fixation or the number of fusion segments. [ Conclusion ] Lumbar fusion can increase the incidence of ASD, and is related with laminectomy and the existence of preoperative ASD, but is not related with internal fixation and the number of lumbar fusion segments. However, there is a moderate possibility of selection bias, performance bias and publication bias in this review because of the small number of the included studies, which may weaken the strength of the evidence of our results. More large sample size, high -quality RCTs are needed.%[目的]对腰椎融合术加速邻近节段椎间盘退变进行系统评价.[方法]按照Coehrane协作网制订的检索策略进行检索,计算机检索MEDLINE(1966~2010年8月)、EMBASE(1974~2010年8月)、Cochrane图书馆(2010年第8期)、中国生物医学文献数据库(CBM,1978~2010年8月)、中国期刊全文数据库(CNKI,1994~2010年8月)、中文科技期刊全文数据库(VIP,1989~2010年8月)及万方数据库(1979~2010年8月).手工检索相关的中英文骨科杂志和会议论文.纳入腰椎融合术后发生邻近节段椎间盘

  15. Degenerative Change in the Adjacent Segments to the Fusion Site after Posterolateral Lumbar Fusion with Pedicle Screw Instrumentation : A Minimum 4-Year Follow-up

    OpenAIRE

    Hayashi, Tetsuo; Arizono, Takeshi; Fujimoto, Toshihiro; Morooka, Takaaki; Shida, Junichi; Tokito, Takeshi; Fukumoto, Shinichi; Masuda, Sachio

    2008-01-01

    Background. Controversy remains regarding the subsequent degeneration of adjacent segments, and little reliable information could be found in the literature regarding long-term clinical results and adjacent segment degeneration. The objective of this study is to investigate the degenerative change of adjacent segments to the fusion site and clinical outcome after posterolateral lumbar fusion with pedicle screw instrumentation and identify the risk factors in degenerative change at adjacent se...

  16. Clinical characteristics and reoperation of symptomatic adjacent segment degeneration post-operation of lumbar fusion%腰椎融合术后症状性邻近节段退变的临床特点和再手术治疗

    Institute of Scientific and Technical Information of China (English)

    孙浩林; 李淳德; 刘宪义; 邑晓东; 刘洪; 卢海霖; 李宏; 于峥嵘; 赵硕

    2012-01-01

    Objective:To evaluate the clinical characteristics and reoperation of symptomatic adjacent segment degeneration post-operation of lumbar fusion. Methods;In the study, 28 cases of symptomatic adjacent segment degeneration post-operation of lumbar fusion from May 2007 to April 2012 were retrospectively reviewed,with an average age of (64. 3±8. 7) years. The mean period between reoperation and primary fusion surgery was (47. 5 ±30. 8) months. Symptomatic adjacent segment degeneration located in cephalic segments in 12 cases, in caudal segments in 14 cases and in both segments in 2 cases. Of all the 28 patients, 12 suffered from lumbar stenosis, other 13 from lumbar disc herniation and still other 3 from both lumbar stenosis and disc herniation, of whom 11 were together with segment instability. Localization diagnoses of 19 cases were clear and other 9 received diagnostic nerve root block. The cases were divided into two groups by the type of reoperation, of which 8 cases were in adjacent degenerative segment nonfusion group and the other 20 cases in adjacent degenerative segment fusion group. The clinical results were assessed by lumbar pain visual analog score (VAS) and lower limber pain VAS, lumbar Japanese Orthopedic Association (JOA) score and Prolo functional score before operation and in the final follow-up. Results; In adjacent degenerative segment nonfusion group, the average operation time was (86. 3±17. 1) min and average blood volume was (125. 0±37. 8 ) mL of reoperation and 1 case with dural injury; and in adjacent degenerative segment fusion group, the average operation time was (201.6± 71. 0) min and average blood volume was (313. 6±18. 9) mL of revision surgery and 4 cases with dural injury. The average follow-up period was 25. 5 months. In the final follow-up,lumbar pain VAS,lower limber pain VAS, lumbar JOA score and Prolo functional score of adjacent degenerative segment nonfusion group were 2.4± 1. 2, 2. 8±1.4,23. 5±4. 2 and 8. 2±1

  17. 单节段与多节段腰椎融合术后邻近节段退变的临床观察%Clinical observation on the incidence of adjacent segment degeneration after single or multi-level lumbar fusion surgery

    Institute of Scientific and Technical Information of China (English)

    王凌挺; 徐宏光; 王弘

    2014-01-01

    目的:探讨单节段与多节段腰椎融合术后邻近节段退变的临床观察。方法:选取2007年5月~2011年8月在我科诊疗并接受腰椎融合术的61例病例,根据手术方式不同,主要分为单节段组和多节段组。通过测量椎间隙高度JOA评分、Prolo功能评分以及Pfirrmann评分系统,对患者术前、术后以及2年后随访的情况进行评分。结果:两组术后JOA评分、Prolo功能评分明显优于术前,但在末次随访评分中,多节段组明显高于单节段组(P<0.05);末次随访多节段组患者上、下邻近节段的Pfirrmann评分均明显高于单节段组,而椎间隙高度则明显小于单节段组(P<0.05)。结论:腰椎融合术治疗效果显著,多节段融合术后邻近节段较单节段融合术更易发生退变,选择合适的手术方式可提升治疗效果,改善患者生活质量。%Objective:To observe the incidence of adjacent segment degeneration after single or multi-segmental lumbar fusion surgery .Methods:Sixty-one patients undergone lumbar fusion for degenerative disease between May 2007 and August 2011 in our department were allocated to treatment group with single-level arthrodesis or multi-segment fusion on the treatment policy basis .The impacts on the incidence of adjacent segment degeneration were evaluated by comparing the total scores with the two groups concerning the height of intervertebral space measured ,Japanese Orthopaedic Association(JOA) scoring, Prolo functional scale and Pfirrmann score before and after surgery as well as conditions in two years of follow-up.Results:The postoperative scores for JOA and Prolo function were significantly better than those before surgery ,yet the scores by the final follow-up were better in group with multiple segment fusion than those treated with single-level arthrodesis(P<0.05).In addition,final follow-up of patients with multiple segment interventions showed higher scores by

  18. 腰椎融合节段数与术后相邻节段退变及远期疗效的关系%Correlation between fusion segment number of lumbar vertebra and postoperative adjacent segment degeneration and long term curative effect

    Institute of Scientific and Technical Information of China (English)

    赵宇; 杨开舜; 李绍波

    2013-01-01

    Objective To investigate the correlation between fusion segment number of lumbar vertebra and clinical effects and postoperative adjacent segment degeneration. Methods Retrospective analysis was made in the clinical data of 135 patients undergoing post approach screw fixation of vertebral pedicle and posterolateral bone graft fusion in our hospital from June 2005 to December 2011. According to the number of lumbar fusion segments, those patients were divided into three groups. Group A was single segment fusion( 56 cases ); group B was double segments fusion( 42 cases ); groups C was multi - segments fusion(≥ 3 segments, 37 case ). Comparison and analysis were made in the long term curative effect and adjacent segment degeneration among the three groups. Results The postoperative follow - up time for the three groups was( 2. 6 ±0. 3 )years,( 2. 3 ±0. 5 )years,and( 2. 4 ±0. 5 )years, respectively( P >0. 05 ). The ODI index and intervertebral height of group C at the last time of follow - up was( 23. 5 ± 9. 4 )% and ( 0.64 ±0.07 )cm,respectively, which were all higher than those of the other two groups. Among the 135 cases, ASD occurred in 19 patients including 5 ones in group A( 8. 9% ) ,6 ones in group B( 14. 3% ), and 8 ones in group C( 21.6% ). The incident in group C was higher than that in group A,however,the difference was not significant P >0.05 ). In group A,the UCLA increased by 1 grade in 5 cases; in group B, that increased by 1 grade in 4 cases, by 2 grades in one case, and by 3 grades in one case; in group C, that increased by 1 grade in one case, by 2 grades in 4 ones, and by 3 grades in 3 ones. When the UCLA increased by 2 - 4 grades the incidence in group C was significantly higher than those in the other two groups( P <0. 05 ). Among the 5 cases of ASD in group A, curative effect did not change in 3 ones and decreased by 2 grades in one. Among the 6 cases in group B, that did not change in two, decreased by 1 grade in three, and decreased by 2

  19. PVP治疗骨质疏松性椎体压缩性骨折对患椎邻近椎体退变和骨折发生率的影响%Adjacent segment degeneration and again fracture incidence of influence after PVP treat traumatic compressibility vertebral fracture

    Institute of Scientific and Technical Information of China (English)

    隋杰; 李志忠; 林永新; 孙国栋; 焦根龙; 任炼

    2011-01-01

    目的 分析经皮椎体成形术(PVP)治疗骨质疏松性椎体压缩性骨折对患椎邻近椎体退变及骨折发生率的影响.方法 骨质疏9松性椎体压缩骨折患者51例,随机分为手术组30例和对照组21例,分别采用PVP治疗和保守治疗.通过X线片测算两组治疗前及治疗后1 a患椎上下椎体前缘压缩率、中柱压缩率、后倾角(θ角).观察治疗后1 a两组患椎邻近椎体的退变情况及骨折发生率.结果 手术组术后1 a患椎上下椎体前缘压缩率、中柱压缩率及θ角均较对照组增大(P均<0.01).手术组术后1 a发生患椎邻近椎体骨折5例(16.7%),对照组无邻近椎体骨折发生(P<0.05).结论 PVP治疗骨质疏松椎体压缩性骨折可加速患椎邻近椎体退变,并增加邻近椎体骨折的风险.%Objective To analysis adjacent segment degeneration and again fracture incidence of influence that percutaneous vertebroplasty(PVP) treat traumatic compressibility vertebral fracture postoperative.Methods 51 patients diagnosed with osteoporotic vertebral compression fractures ,30 cases were treated with PVP as surgical treatment group, and 21 cases for the conservative group.All patients examined with the standards X-ray,then observed variation of adjacent vertebral body height and wedge angle,compared with these results after 1 a.The adjacent segment degeneration and the risk of fracture again with 1 a after operation in two groups were recorded.Results There were difference in adjacent vertebral body height and wedge angle between two groups in 1 a after operation ( P <0.05) ,incidence of fracture in surgical treatment group was 16.7%.The control group was without adjacent vertebral fractures occurred.Conclusion PVP for the treatment of traumatic compressibility vertebral fracrure can accelerate with adjacent segment degeneration, and increase the risk of fracture of adjacent segment.

  20. Clinical Effectiveness and Influence on Adjacent Segments Degeneration after Single-level Anterior Cervical Fusion%单节段颈椎前路减压融合术对邻近节段退变的影响及疗效观察

    Institute of Scientific and Technical Information of China (English)

    郑兆君; 邱玉金; 刘文华; 李军磊; 曹亮波

    2013-01-01

    Objective To evaluate the clinical effectiveness and influence on adjacent segments degenera-tion after single-level anterior cervical fusion.Methods A retrospective study was given to 40 patients who underwent single-level anterior cervical fusion from Aug.2007 to Dec.2010 and 40 patients with cervical spondylosis of the same age for the same period(imaging showed only a single segment lesions ) underwent conservative therapypatient .The disc degeneration were evaluated using intervertebral disc height and disc Pfirrmann MRI degeneration score .The clinical ef-fectiveness were evaluated using cervical JOA score ,the neck disability index(NDI) .Results The surgical group and conservative group had a statistically significant difference (P0.05) in cervi-cal JOA score and NDI than 1 week after that.Conclusion Anterior cervical discectomy and fusion can lead to degener-ation at the adjacent segment,but the clinical effectiveness are worthy of recognition .%  目的探讨单节段颈椎前路减压融合术对邻近节段退变的影响及手术疗效.方法回顾性分析2007年8月~2010年12月我科收治的40例行单节段颈椎前路减压融合术患者及同期同年龄段颈椎病(影像学显示仅单节段病变)且行保守治疗的患者资料.采用椎间隙高度及椎间盘Pfirrmann MRI退变评分作为评价椎间盘退变指标;采用颈椎JOA评分、颈椎功能障碍指数(NDI)作为手术疗效评价指标.结果术后24个月时,与对照组相比,手术组邻近节段椎间隙高度明显降低,差异有统计学意义(P0.05).结论颈椎前路减压融合术后邻近节段易发生退变,但疗效值得肯定.

  1. Effects of unisegmental disc compression on adjacent segments: an in vivo animal model.

    Science.gov (United States)

    Unglaub, Frank; Guehring, Thorsten; Lorenz, Helga; Carstens, Claus; Kroeber, Markus W

    2005-12-01

    It is controversial whether fusion of discs in the spine leads to increased degeneration on the remaining discs or whether the degenerative changes are merely a part of the inevitable natural history process. To determine the effects of unisegmental compression and subsequent recovery on adjacent segments, we studied histology, radiology and intradiscal pressure using an in vivo rabbit model. Fifteen New Zealand rabbits were divided in to three groups of five. In the first group, the intervertebral disc L4-L5 of the lumbar spine was axially loaded for 28 days with an external loading device. In the second group, the intervertebral disc was compressed for 28 days and allowed to recover for an equal amount of time, with the loading device removed. Five animals underwent a sham operation, in which the external loading device was situated, but their discs remained unloaded for 28 days. The intradiscal pressure was determined in the loaded discs as well as in the cranial and caudal adjacent discs. Lateral radiographs were taken from each subjected intervertebral disc with adjacent vertebral bodies and the cranial and caudal adjacent segments. The compressed discs showed lower intradiscal pressure in comparison with the control group, which remained unloaded. In the cranial and caudal discs adjacent to the loaded discs the average intradiscal pressure was similar to the unloaded controls. The loaded discs demonstrated a significant decrease in disc space. No discs adjacent to the loaded discs changed in height. The lamellar architecture of the inner, middle, and outer annulus became more disorganized in the loaded discs. The nucleus pulposus showed increase of mucoid degeneration and increased cell death. Intervertebral discs from the control group and the adjacent discs to the compressed discs maintained their normal morphology. This study shows that mechanical loading of discs in the spine can cause rapid degeneration. Adjacent discs, however, did not change in terms

  2. 颈椎间盘置换及前路椎间融合治疗单节段颈椎间盘突出症:谁更多影响邻近节段发生退变?%Anterior cervical disc replacement and anterior cervical decompression and fusion for treating single segment cervical disc herniation:which has greater effects on adjacent segment degeneration?

    Institute of Scientific and Technical Information of China (English)

    刘威; 盛伟斌; 张健; 邓强; 郭海龙

    2016-01-01

    背景:有研究表明,颈椎间盘置换及前路固定融合治疗颈椎病可以取得较好的临床效果,但是哪种术式在避免邻近节段退变方面更具优势尚无定论。目的:比较颈椎间盘置换与前路固定融合治疗单节段颈椎间盘突出症对邻近节段的近期影响。方法:收集2009年1月至2012年12月以“颈椎间盘突出症”为诊断收入院并行单节段颈椎间盘置换或颈前路椎间盘切除融合患者178例的临床资料,进行回顾性分析,其中前路固定融合组116例,颈椎间盘置换组62例。结果与结论:①评价:两组患者末次随访时目测类比评分、日本骨科协会评估治疗评分、颈椎功能障碍指数均较治疗前明显改善(P 0.05)。前路固定融合组术后3个月时手术节段基本融合,活动度丧失,末次随访时邻近上位节段活动度与邻近下位节段活动度明显增加,且上位节段活动度增加的度数较下位节段大(P 0.05). At 3 months after surgery, in the anterior cervical decompression and fusion group, surgical segment was confluent, and range of motion lost. During final fol ow-up, range of motion of adjacent upper segment and adjacent lower segment was significantly increased, and the increased range of motion in the upper segment was bigger than that of the lower segment (P < 0.05). (3) During final fol ow-up, X-ray films and MRI images revealed the number of degenerated adjacent segment was more in the anterior cervical decompression and fusion group than in the anterior cervical disc replacement group (P <0.05). The number of degenerated middle and upper segments was more than that of the lower segment in both groups (P < 0.05). (4) The findings confirmed that anterior cervical disc replacement or anterior cervical decompression and fusion for treating cervical disc herniation could effectively relieve nerve symptoms of patients. However, compared with the anterior cervical disc

  3. Disckectomy, Partial Adjacent Centrum Resection, Bone Graft with Titanium Mesh and Titanium Plate Fixation for the Treatment of Single Segment Cervical Disc Degeneration with Adjacent Vertebral Posterior Osteophyte%椎间盘及部分椎体切除加钛网植骨钛板内固定术治疗单节段颈椎椎间盘突出伴椎体后缘骨赘

    Institute of Scientific and Technical Information of China (English)

    孙继飞; 何强; 刘振利; 陈庆胜

    2012-01-01

    目的 评价颈椎椎间盘及相邻椎体部分切除加钛网植骨钛板内固定术治疗单节段颈椎椎间盘退变突出伴相邻椎体后缘骨赘的疗效. 方法 应用颈椎椎间盘及相邻椎体部分切除加钛网植骨钛板内固定术治疗单节段颈椎椎间盘退变突出伴相邻椎体后缘骨赘22例.取颈椎前路手术切口,术中仅切除突出的椎间盘及相邻椎体的1/3~ 1/2,使脊髓得到彻底的减压.再用填满碎骨的钛网植于骨缺损处加用钛板螺丝钉内固定,固定范围仅限于相邻椎体.术前和术后通过神经功能JOA评分、颈部轴性症状、颈椎动态侧位片和颈椎MRI比较临床疗效. 结果 均获随访,平均15(6 ~24)个月,术后JOA评分优良率86.4%,颈部轴性症状减轻,脊髓功能明显得到恢复.颈椎活动度良好.X线检查见钛网植骨及钛板内固定良好,未见不稳现象.MRI示颈髓压迫解除. 结论 颈椎椎间盘及相邻椎体部分切除加钛网植骨钛板内固定术治疗单节段颈椎椎间盘突出伴相邻椎体骨赘效果显著,可最大限度地保留颈椎节段的活动度.%Objective To evaluate the clinical effects of disckectomy, partial adjacent centrum resection , bone graft with titanium mesh and titanium plate fixation for the treatment of single segment cervical disc degeneration with adjacent vertebral posterior osteophyte. Methods There were 22 cases received this kind of surgical procedure. By anterior cervical incision, the herniated disc and only 1/3 to 1/2 of the adjacent vertebral body were removed for the decompression of the spinal cord. Then the titanium mesh filled with the small bones was implanted in the bone defect followed by titanium screw fixation. The fixation was limited to the adjacent vertebral bodies. Preoperative and postoperative neurological functions of the JOA score, the cervical axial symptoms, the cervical dynamic radiographs and cervical spine MRI were used to compare the clinical

  4. Disc height and anteroposterior translation in fused and adjacent segments after lumbar spine fusion

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    Frobin, Wolfgang

    2003-09-01

    Full Text Available In a series of 46 patients the effects of spinal fusion upon intervertebral height and sagittal alignment in operated and non-operated segments were retrospectively evaluated on digitized radiographs. Data was compared with age- and gender-normalized standard values. The objective was to evaluate the influence of different types of spine fusions primarily upon adjacent segments, particularly in terms of degeneration and sagittal profile of the lumbar spine. Incidence of adjacent segment degeneration (ASD is still highly controversial. However, not every degeneration adjacent to spinal fusion must be caused by the fusion and responsibility of the fusion for ASD may vary with its range and type. Distortion Corrected Roentgen Analysis (DCRA was utilized. DCRA is a proven valid, reliable, observer-independent, and accurate tool for assessment of these parameters over time and in comparison with "normal" cohorts. With this method the exact posture of the patients needs not to be known.There was little evidence for serious fusion-related ASD within an average of 40 months follow-up. No difference could be detected for rigid vs. non-rigid fusion and instrumented vs. non-instrumented techniques. Temporary postoperative distraction effects could be detected in operated and non-operated segments. Absolute preoperative values for intervertebral height and vertebral slip were age-related. Retrospectively, the choice of segments for fusion was clearly based upon radiological criteria. Thus we conclude that radiological parameters have an obvious clinical relevance for decision-making and need to be quantified. Within the limitations of this pilot study, true fusion related ASD seems to be infrequent.

  5. 腰椎经后路椎体间融合后单边或双边固定对邻近节段退变的影响%Comparative study of adjacent segment degeneration after posterior lumbar interbody fusion with unilateral or bilateral pedicle screw instrumentation

    Institute of Scientific and Technical Information of China (English)

    林斌; 张文彬; 周琴; 张峰; 敖庆芳; 俞辉; 陆成武

    2014-01-01

    adjacent segment degeneration (ASD) by preventing contralat-eral cephalad adjacent facet joint from injury by pedicle screw insertion. However, there are few studies on long-term fol-lowup comparative study on ASD between unilateral and bilateral pedicle screw fusion. Objective:To compare ASD after posterior lumbar interbody fusion (PLIF) using either unilateral or bilateral pedicle screw instrumentation for patients with L4-L5 intervertebral disc herniation. Methods:A total of 101 patients with L4-L5 intervertebral disc herniation were treated with PLIF between February 2006 and December 2007 and enrolled in the study. There were 42 cases with unilateral fixation and 59 cases with bilateral fixa-tion. The follow-up period of all patients were more than 5 years. Radiologic ASD was evaluated at three segments:the first cephalad adjacent segment, the second cephalad adjacent segment, and caudal adjacent segment. ODI score was used to evaluate vertebral function at the last follow-up. Results:In the unilateral fixation group, the incidence of ASD of the first cephalad adjacent segment, second cephalad adja-cent segment and caudal adjacent segment was 57.1%(24/42), 45.2%(19/42) and 38.1%(16/42) ), respectively. In the bilat-eral fixation group, the incidence of ASD of the three segments was 72.9%(43/59), 68.0%(40/59) and 50.8%(30/59), re-spectively. There were no significant differences in the incidences of ASD of the first cephalad and caudal adjacent segment between groups, while significant difference was found in the second cephalad adjacent segment degeneration between two groups. ODI score was 25.6 ± 5.9 in the unilateral fixation group and 28.4 ± 5.2 in the bilateral fixation group (t=-2.503, P=0.014). Conclusions:As compared with bilateral fixation, there is a lower incidence of radiologic ASD after unilateral pedicle screw fixation in PLIF, especially when the fixation is in second cephalad adjacent segment in patients with single lumbar interver-tebral disc

  6. Incidence and risk factors of adjacent segment disease following posterior decompression and instrumented fusion for degenerative lumbar disorders

    Science.gov (United States)

    Wang, Hui; Ma, Lei; Yang, Dalong; Wang, Tao; Liu, Sen; Yang, Sidong; Ding, Wenyuan

    2017-01-01

    Abstract The purpose of this study was to explore incidence and risk factors of adjacent segment disease (ASD) following posterior decompression and instrumented fusion for degenerative lumbar disorders, and hope to provide references in decision making and surgical planning for both spinal surgeon and surgically treated patients. By retrieving the medical records from January 2011 to December 2013 in our hospital, 237 patients were retrospectively reviewed. According to the occurrence of ASD at follow up, patients were divided into 2 groups: ASD and N-ASD group. To investigate risk values for the occurrence of ASD, 3 categorized factors were analyzed statistically: Patient characteristics: age, sex, body mass index (BMI), bone mineral density (BMD), duration. Surgical variables: surgical strategy, number of fusion level, surgery segment, surgery time, blood loss, intraoperative superior facet joint violation. Radiographic parameters: preoperative lumbar lordosis, preoperative angular motion at adjacent segment, preoperative adjacent segment disc degeneration, preoperative paraspinal muscle degeneration. Postoperative ASD was developed in 15 of 237 patients (6.3%) at final follow up. There was no statistically significant difference between the 2 groups in patient characteristics of age, sex composition, BMD, duration, while the BMI was higher in ASD group than that in N-ASD group. There was no difference in surgical variables of surgical strategy, number of fusion level, surgery segment, surgery time, blood loss, while intraoperative superior facet joint violation was more common in ASD group than that in N-ASD group. There was no difference in radiographic parameters of preoperative lumbar lordosis, preoperative paraspinal muscle degeneration, while preoperative adjacent segment disc degeneration were more severe in ASD group than that in N-ASD group. The Logistic regression analysis revealed that, BMI >25 kg/m2, preoperative disc degeneration, and superior

  7. Incidence and risk factors of adjacent segment disease following posterior decompression and instrumented fusion for degenerative lumbar disorders.

    Science.gov (United States)

    Wang, Hui; Ma, Lei; Yang, Dalong; Wang, Tao; Liu, Sen; Yang, Sidong; Ding, Wenyuan

    2017-02-01

    The purpose of this study was to explore incidence and risk factors of adjacent segment disease (ASD) following posterior decompression and instrumented fusion for degenerative lumbar disorders, and hope to provide references in decision making and surgical planning for both spinal surgeon and surgically treated patients.By retrieving the medical records from January 2011 to December 2013 in our hospital, 237 patients were retrospectively reviewed. According to the occurrence of ASD at follow up, patients were divided into 2 groups: ASD and N-ASD group. To investigate risk values for the occurrence of ASD, 3 categorized factors were analyzed statistically: Patient characteristics: age, sex, body mass index (BMI), bone mineral density (BMD), duration. Surgical variables: surgical strategy, number of fusion level, surgery segment, surgery time, blood loss, intraoperative superior facet joint violation. Radiographic parameters: preoperative lumbar lordosis, preoperative angular motion at adjacent segment, preoperative adjacent segment disc degeneration, preoperative paraspinal muscle degeneration.Postoperative ASD was developed in 15 of 237 patients (6.3%) at final follow up. There was no statistically significant difference between the 2 groups in patient characteristics of age, sex composition, BMD, duration, while the BMI was higher in ASD group than that in N-ASD group. There was no difference in surgical variables of surgical strategy, number of fusion level, surgery segment, surgery time, blood loss, while intraoperative superior facet joint violation was more common in ASD group than that in N-ASD group. There was no difference in radiographic parameters of preoperative lumbar lordosis, preoperative paraspinal muscle degeneration, while preoperative adjacent segment disc degeneration were more severe in ASD group than that in N-ASD group. The Logistic regression analysis revealed that, BMI >25 kg/m, preoperative disc degeneration, and superior facet joint

  8. The Comparison between Cervical Artificial Disc Arthroplasty and Anterior Cervical Decompression and Fusion on the Influence of the Adjacent Segments Degeneration%颈椎间盘置换术与颈椎前路减压融合术对邻近节段退变情况影响的比较

    Institute of Scientific and Technical Information of China (English)

    王鲲鹏; 邱玉金; 王玉凤; 刘守勇; 吴磊磊

    2013-01-01

    Objective To compare CADR with ACDF on the influence of the adjacent segments degenera-tion.Methods From February 2008 to October 2010,a total of 62 cases of cervical spondylosis was retrospectively re-viewed.All the patients were divided into CADR group and ACDF group ,depending on different surgical methods .The symptoms and neurological function were evaluated by the cervical Japanese Orthopaedic Association ( JOA) Scores and neck disability index ( NDI ) .The Cobb angle of C 2~7 and the mobility of adjacent segments were valuated the cervical range of mobility and degeneration .Results Compared with the preoperation , the last follow-up neurological function significantly improved ,the difference was statistically significant ( P0 .05 ) .At last follow-up Cobb angle of C 2~7 and the mobility of adjacent upper and lower segments in CADR group were similar to the preoperative ,there was no significant difference statistically (P>0.05).And there was significant difference statistically in ACDF group and between the groups ( P<0.05) .Conclusion CADR is less influ-ential on the adjacent segments degeneration postoperative .%目的:比较分析颈椎间盘置换术( CADR )与颈椎前路减压融合术( ACDF )对邻近节段退变情况的影响。方法回顾性分析2008年2月~2011年10月手术治疗的62名患者,根据术式不同,分为CADR组与ACDF组。采用颈椎JOA、NDI评分评价症状及神经功能,C2~7 Cobb角和手术相邻节段活动度评价颈椎活动范围及退变情况。结果与术前比较,末次随访时两组患者神经功能明显改善,组内差异有显著性(P<0.05),但组间比较差异无显著性(P>0.05)。与术前相比,末次随访时CADR组C2~7 Cobb角和手术相邻上、下节段活动度相近,差异无显著性(P>0.05);ACDF组内比较与两组间末次随访时比较C2~7 Cobb角和手术相邻上、下节段活动度,差异有显著性( P<0.05

  9. Load Rate of Facet Joints at the Adjacent Segment Increased After Fusion

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    Hui Li

    2015-01-01

    Full Text Available Background: The cause of the adjacent segment degeneration (ASD after fusion remains unknown. It is reported that adjacent facet joint stresses increase after anterior cervical discectomy and fusion. This increase of stress rate may lead to tissue injury. Thus far, the load rate of the adjacent segment facet joint after fusion remains unclear. Methods: Six C2-C7 cadaveric spine specimens were loaded under four motion modes: Flexion, extension, rotation, and lateral bending, with a pure moment using a 6° robot arm combined with an optical motion analysis system. The Tecscan pressure test system was used for testing facet joint pressure. Results: The contact mode of the facet joints and distributions of the force center during different motions were recorded. The adjacent segment facet joint forces increased faster after fusion, compared with intact conditions. While the magnitude of pressures increased, there was no difference in distribution modes before and after fusion. No pressures were detected during flexion. The average growth velocity during extension was the fastest and was significantly faster than lateral bending. Conclusions: One of the reasons for cartilage injury was the increasing stress rate of loading. This implies that ASD after fusion may be related to habitual movement before and after fusion. More and faster extension is disadvantageous for the facet joints and should be reduced as much as possible.

  10. Load Rate of Facet Joints at the Adjacent Segment Increased After Fusion

    Institute of Scientific and Technical Information of China (English)

    Hui Li; Bao-Qing Pei; Jin-Cai Yang; Yong Hai; De-Yu Li; Shu-Qin Wu

    2015-01-01

    Background:The cause of the adjacent segment degeneration (ASD) after fusion remains unknown.It is reported that adjacent facet joint stresses increase after anterior cervical discectomy and fusion.This increase of stress rate may lead to tissue injury.Thus far,the load rate of the adjacent segment facet joint after fusion remains unclear.Methods:Six C2-C7 cadaveric spine specimens were loaded under four motion modes:Flexion,extension,rotation,and lateral bending,with a pure moment using a 6° robot arm combined with an optical motion analysis system.The Tecscan pressure test system was used for testing facet joint pressure.Results:The contact mode of the facet joints and distributions of the force center during different motions were recorded.The adjacent segment facet joint forces increased faster after fusion,compared with intact conditions.While the magnitude of pressures increased,there was no difference in distribution modes before and after fusion.No pressures were detected during flexion.The average growth velocity during extension was the fastest and was significantly faster than lateral bending.Conclusions:One of the reasons for cartilage injury was the increasing stress rate of loading.This implies that ASD after fusion may be related to habitual movement before and after fusion.More and faster extension is disadvantageous for the facet joints and should be reduced as much as possible.

  11. Adjacent segment disease in degenerative pathologies with posterior instrumentation

    OpenAIRE

    Ana Guadalupe Ramírez Olvera; Manuel Villarreal Arroyo; Luis Mario Hinojosa Martínez; Enrique Méndez Pérez; Luis Romeo Ramos Hinojosa

    2015-01-01

    OBJECTIVE: To establish the real incidence of adjacent segment disease after fusion, and to identify the levels and predisposing factors for the pathology, as well as the functional results. METHODS: a retrospective case series study with level of evidence IIB, in a sample of 179 patients diagnosed with stenosis of the lumbar spine, spondylolisthesis and degenerative scoliosis, submitted to surgery in the period 2005 to December 2013, with posterior instrumentation and posterolateral fusion, ...

  12. Short-term clinical results of interspinous dynamic fixation of Coflex for the prevention of adjacent segment degeneration after lumbar fusion%棘突间动态稳定装置Coflex预防腰椎融合术后相邻节段退变的短期随访疗效观察

    Institute of Scientific and Technical Information of China (English)

    周盛源; 陈雄生; 贾连顺; 朱巍; 房雷; 蔡弢艺

    2012-01-01

    Objective To observe the short-term clinical results of the adjacent segment degeneration after the implantation of Coflex system at the interspinous space of adjacent segment to lumbar fusion.Methods Fifty patients with grade Ⅲ disc (Thompson MRI classification) of adjacent segment to lunbar fusion were included and divided alternately into two groups according to the order of hospitalization from January to November 2009.Coflex system was implanted at the interspinous space of adjacent segment to lumbar fusion in 25 patients as Coflex group,the other 25 patients did not have any surgical treatment were as control group.The followed up time was 2 years. Visual analogue scale (VAS) score of low back pain,changes of disc height and motion range of adjacent segment to lumbar fusion on X-ray imaging were evaluated by independent sample t-test or paired samples t-test.Results There were 22 patients in Coflex group and 21 patients in control group were followed up 2 years post-operation.The difference of VAS score between two groups was no significance ( P > 0.05 ).In Coflex group,the change of postoperative disc height was no significance (P > O.05 ),but the motion range was significantly reduced to 47% of the preoperative value ( t =7.99,P < 0.05 ). In control group,the postoperative disc height decreased slightly,without significant difference to the preoperative value ( P > 0.05 ). Between the two groups,no differences of the disc height and motion range were found before operation,but the differences of the disc height changes(t =6.7,P < 0.05 ) and motion rang ( t =- 14.5,P < 0.05 ) were significant in 2 years post-operation. No complications such as Coflex system loosen, immigration and spinal process fracture were occurred.Conclusions Coflex system can obviously limit the motion range and maintain the disc space height of adjacent segment to lumbar fusion,and prevent its degeneration in some degree.%目的 研究腰椎融合节段相邻退变节

  13. Study of adjacent segment degeneration after internal fixation lumbar fusion with pedicle screw%腰椎滑脱椎弓根螺钉内固定融合术后邻近节段退变的相关研究

    Institute of Scientific and Technical Information of China (English)

    赵文国; 沈冰; 张柳; 王勇贵; 贾鹏

    2008-01-01

    Objective To observe the changes of the height of intervertebral discs of the segments adjacent to the fusional and instrumental area after the operation and the relation between the changes of height of intervetebral discs in the adjacent segments and the angle of the pedicle screw.Methods Thirty-one patients who underwent internal fixation from September 2004 to March 2006 were retrospectively analyzed.The intervertebral discs height of adjacent segment was studied.The influence of"Suspensory fixation"on the changes of height of adjacent intervertebral discs was compared.The relation between the changes of the height of the upper adjacent intervertebral discs and the angle of pedicle screw was analyzed.Results The mean follow-up period for the patients was 13.5 months(10-16 months).In the operating-group,the height of the adjacent intervertebral disc decreased slightly,but the changes had no statistical significance(P>0.05).Between the group fixed between L5 and S1 and group fixed between L4and L5,the changes of the height of the upper adjacent intervertebral discs had no obvious difference(P>0.05).In the group fixed between L4 and L5,there had no obvious difference between the changes of the height of the upper adjacent intervertebral discs and the changes of the height of the lower one(P>0.05).When the operating-group were divided into two groups according to the angle of pedicle screw (<6°or>6°),the changes of the height of the upper adjacent intervertebral discs had no obvious difference(P>0.05).But there had positive and correlative relation between changes of the height of the adjacent intervertebral discs and the angle of pedicle screw(r=0.373,P=0.039).Conclusion "Suspensory fixation"has no different influence on the changes of height of adjacent intervertebral discs.There has no difference on the risk of degeneration between upper and lower segment adjacent to the fusional area.There has positive and correlative relation between the changes

  14. Adjacent segment disease in degenerative pathologies with posterior instrumentation

    Directory of Open Access Journals (Sweden)

    Ana Guadalupe Ramírez Olvera

    2015-03-01

    Full Text Available OBJECTIVE: To establish the real incidence of adjacent segment disease after fusion, and to identify the levels and predisposing factors for the pathology, as well as the functional results. METHODS: a retrospective case series study with level of evidence IIB, in a sample of 179 patients diagnosed with stenosis of the lumbar spine, spondylolisthesis and degenerative scoliosis, submitted to surgery in the period 2005 to December 2013, with posterior instrumentation and posterolateral fusion, with follow-up from 2007 until May 2014, in which the symptomology and radiographic findings were evaluated, to establish the diagnosis and treatment. RESULTS: the study included 179 patients diagnosed with stenosis of the lumbar spine (n=116, isthmic and degenerative spondylolisthesis (n=50 and degenerative scoliosis (n=13; during the study, 20 cases of adjacent level segment were identified, 80% of which were treated surgically with extension of the instrumentation, while 20% were treated conservatively with NSAIDs and therapeutic blocks. CONCLUSION: An incidence of 11% was found, with an average of 3.25 years in diagnosis and treatment, a prevalence of females and diagnosis of stenosis of the lumbar canal on posterior instrumentation, a predominance of levels L4-L5; 80% were treated with extension of the instrumentation. The complications were persistent radiculopathy, infection of the surgical wound, and one death due to causes not related to the lumbar pathology.

  15. 后方韧带复合体对腰椎椎间融合术后早期相邻节段退变的影响%Effect of the Posterior Ligament Complex on the Adjacent Segment Degeneration after Posterior Lumbar Interbody Fusion

    Institute of Scientific and Technical Information of China (English)

    何方生; 吴兵; 盛文辉; 王春辉; 王自刚; 尚琦松; 韩鹏远; 陈操

    2016-01-01

    目的 探讨后方韧带复合体对腰椎椎间融合术后早期相邻节段退变的影响.方法 2000年1月至2010年1月在我科实施后路腰椎减压椎间融合内固定治疗L4~5椎间盘突出患者60 例.A组(30 例)行保留后方韧带复合体的腰椎椎间融合术( posterior lumbar interbody fusion,PLIF),B组(30 例)行切除后方韧带复合体的PLIF术.比较两组手术前、后日本骨科协会( Japanese orthopaedic association,JOA)评分及改善率.术前、末次随访时测量腰椎X线片上L3~4椎间盘的高度和椎间隙动态角度、L3~4椎体滑移距离并进行比较.术前及末次随访时对L3~4椎间盘进行Pfir-rmann分级.结果 手术前、后两组患者的JOA评分差异有统计学意义( P0. 05),两组之间改善率差异无统计学意义(P>0. 05).A组9 例患者出现了L3~4节段的邻近节段退变( adjacent segment disease,ASD),B组17 例出现了L3~4节段的ASD.其中A、B两组均有2 例患者为有症状的ASD.术前两组患者X线片上L3~4椎间盘的高度、椎间隙动态角度、L3~4椎体滑移距离相比差异均无统计学意义( P>0. 05),而末次随访时差异有统计学意义( P0. 05). A group had 9 patients with lumbar 3/4 segment of the ASD,B group had 17 cases of lumbar 3~4 segment ASD. Among them,each groups had 2 cases of patients with symptoms of ASD. There were not difference in 3~4 lumbar intervertebral disc height,intervertebral space dy-namic angle ,waist 3 ~ 4 vertebral slip distance . But at the time of last follow - up significant difference could be found( P <0. 05). At the end of the follow-up A group had 6 cases of Pfirrmann grade 1,22 cases of 2,2 cases of grade 3,no 4,5 cases. Bgroup had 4 cases of Pfirrmann grade 1,24 cases of 2,2 cases of grade 3,no 4,5 cases.Conclusion Inlumbarinterbody fusion,posterior ligament complex can decrease the incidence of adjacent segment degeneration.

  16. Effects of rod stiffness and fusion mass on the adjacent segments after floating mono-segmental fusion: a study using finite element analysis.

    Science.gov (United States)

    Jin, Yong Jun; Kim, Young Eun; Seo, Jung Ho; Choi, Hae Won; Jahng, Tae-Ahn

    2013-05-01

    The aims of the present study were to compare the biomechanical effects on the adjacent segments after mono-segmental floating fusion with posterior semi-rigid or rigid stabilization, and to evaluate the effect of the amount of fusion mass on the biomechanical differences. A detailed, nonlinear L1-S1 finite element model had been developed and validated. Then five models were reconstructed by different fixation techniques on the L3-L4 level: rigid fixation with an interbody spacer (Ti + IS), rigid fixation with a large interbody spacer (Ti + IS_all), semi-rigid fixation with an interbody spacer (PEEK + IS), semi-rigid fixation with a large interbody spacer (PEEK + IS_all), and semi-rigid fixation only (PEEK). Analyses were conducted for the case of erect standing position, flexion, and extension motion. At L1-L2 and L2-L3, PEEK + IS demonstrated less inter-segmental rotation and nucleus pressure increments from the intact model compared with Ti + IS. The L4-L5 and L5-S1 levels showed slightly higher values with PEEK + IS, but these differences among the instrumented models were not significant. The motion difference based on the fusion mass at the adjacent levels was at most 3%. All instrumentation cases generated a 55% higher facet contact force at the lower adjacent level (L4-L5) compared to that of the intact model during 26° extension and the largest increment was detected at the upper adjacent level (L2-L3) in the Ti + IS. Instrumentation with Ti + IS markedly increased the stress in the intervertebral disk at the upper adjacent level, while the stress with PEEK + IS appeared largest at the lower adjacent level. Posterior instrumentation with semi-rigid rods may lower the incidence of disk and facet degeneration in the upper adjacent segment compared to rigid rods. On the other hand, the possibility of facet degeneration will be similar for all instrumentation devices in the lower adjacent segment in the long-term. The stiffness difference between rigid and

  17. Fusion angle affects intervertebral adjacent spinal segment joint forces-Model-based analysis of patient specific alignment.

    Science.gov (United States)

    Senteler, Marco; Weisse, Bernhard; Rothenfluh, Dominique A; Farshad, Mazda T; Snedeker, Jess G

    2017-01-01

    This study addresses the hypothesis that adjacent segment intervertebral joint loads are sensitive to the degree of lordosis that is surgically imposed during vertebral fusion. Adjacent segment degeneration is often observed after lumbar fusion, but a causative mechanism is not yet clearly evident. Altered kinematics of the adjacent segments and potentially nonphysiological mechanical joint loads have been implicated in this process. However, little is known of how altered alignment and kinematics influence loading of the adjacent intervertebral joints under consideration of active muscle forces. This study investigated these effects by simulating L4/5 fusions using kinematics-driven musculoskeletal models of one generic and eight sagittal alignment-specific models. Models featured different spinopelvic configurations but were normalized by body height, masses, and muscle properties. Fusion of the L4/5 segment was implemented in an in situ (22°), hyperlordotic (32°), and hypolordotic (8°) fashion and kinematic input parameters were changed accordingly based on findings of an in vitro investigation. Bending motion from upright standing to 45° forward flexion and back was simulated for all models in intact and fused conditions. Joint loads at adjacent levels and moment arms of spinal muscles experienced changes after all types of fusion. Hypolordotic configuration led to an increase of adjacent segment (L3/4) shear forces of 29% on average, whereas hyperlordotic fusion reduced shear by 39%. Overall, L4/5 in situ fusion resulted in intervertebral joint forces closest to intact loading conditions. An artificial decrease in lumbar lordosis (minus 14° on average) caused by an L4/5 fusion lead to adverse loading conditions, particularly at the cranial adjacent levels, and altered muscle moment arms, in particular for muscles in the vicinity of the fusion. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:131-139, 2017.

  18. Failure of cervical arthroplasty in a patient with adjacent segment disease associated with Klippel-Feil syndrome

    Directory of Open Access Journals (Sweden)

    Ioannis D Papanastassiou

    2011-01-01

    Full Text Available Cervical arthroplasty may be justified in patients with Klippel-Feil syndrome (KFS in order to preserve cervical motion. The aim of this paper is to report an arthroplasty failure in a patient with KFS. A 36-year-old woman with KFS underwent two-level arthroplasty for adjacent segment disc degeneration. Anterior migration of the cranial prosthesis was encountered 5 months postoperatively and was successfully revised with anterior cervical fusion. Cervical arthroplasty in an extensively stiff and fused neck is challenging and may lead to catastrophic failure. Although motion preservation is desirable in KFS, the special biomechanical features may hinder arthroplasty. Fusion or hybrid constructs may represent more reasonable options, especially when multiple fused segments are present.

  19. Cervical facet dislocation adjacent to the fused motion segment.

    Science.gov (United States)

    Yokoyama, Kunio; Kawanishi, Masahiro; Yamada, Makoto; Tanaka, Hidekazu; Ito, Yutaka; Kuroiwa, Toshihiko

    2016-01-01

    This study reports on a case that forces re-examination of merits and demerits of anterior cervical fusion. A 79-year-old male was brought to the emergency room (ER) of our hospital after he fell and struck the occipital region of his head following excessive alcohol consumption. Four years prior, he had undergone anterior cervical discectomy and fusion of C5/6 and a magnetic resonance imaging (MRI) performed 3 years after this surgery indicated that he was suffering from degeneration of C6/7 intervertebral discs. After arriving at the ER, he presented motor impairment at level C7 and lower of manual muscle testing grade 1 as well as moderate loss of physical sensation from the trunk and peripheries of both upper limbs to the peripheries of both lower limbs (Frankel B). Cervical computed tomography (CT) indicated anterior dislocation of C6/7, and MRI indicated severe spinal cord edema. We performed manipulative reduction of C6/7 with the patient under general anesthesia. Next, we performed laminectomy on C5-T1 and posterior fusion on C6/7. Postoperative CT indicated that cervical alignment had improved, and MRI indicated that the spinal cord edema observed prior to surgery had been mitigated. Three months after surgery, motor function and sensory impairment of the lower limbs had improved, and the patient was ambulatory upon discharge from the hospital (Frankel D). In the present case, although C5 and 6 were rigidly fused, degeneration of the C6/7 intervertebral disc occurred and stability was compromised. As a result, even slight trauma placed a severe dynamic burden on the facet joint of C6/7, which led to dislocation.

  20. Cervical facet dislocation adjacent to the fused motion segment

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    Kunio Yokoyama

    2016-01-01

    Full Text Available This study reports on a case that forces re-examination of merits and demerits of anterior cervical fusion. A 79-year-old male was brought to the emergency room (ER of our hospital after he fell and struck the occipital region of his head following excessive alcohol consumption. Four years prior, he had undergone anterior cervical discectomy and fusion of C5/6 and a magnetic resonance imaging (MRI performed 3 years after this surgery indicated that he was suffering from degeneration of C6/7 intervertebral discs. After arriving at the ER, he presented motor impairment at level C7 and lower of manual muscle testing grade 1 as well as moderate loss of physical sensation from the trunk and peripheries of both upper limbs to the peripheries of both lower limbs (Frankel B. Cervical computed tomography (CT indicated anterior dislocation of C6/7, and MRI indicated severe spinal cord edema. We performed manipulative reduction of C6/7 with the patient under general anesthesia. Next, we performed laminectomy on C5-T1 and posterior fusion on C6/7. Postoperative CT indicated that cervical alignment had improved, and MRI indicated that the spinal cord edema observed prior to surgery had been mitigated. Three months after surgery, motor function and sensory impairment of the lower limbs had improved, and the patient was ambulatory upon discharge from the hospital (Frankel D. In the present case, although C5 and 6 were rigidly fused, degeneration of the C6/7 intervertebral disc occurred and stability was compromised. As a result, even slight trauma placed a severe dynamic burden on the facet joint of C6/7, which led to dislocation.

  1. The early stage adjacent disc degeneration after percutaneous vertebroplasty and kyphoplasty in the treatment of osteoporotic VCFs.

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    Jun Qian

    Full Text Available BACKGROUND: The purpose of this paper is to determine the early incidence of disc de- generation adjacent to the vertebral body of osteoporotic fracture treated with percutaneous vertebroplasty or balloon kyphoplasty and whether adjacent disc degeneration is accelerated by this two procedures. METHODS: 182 patients with painful vertebral compression fractures were treated. A total of 97 patients were enrolled in this prospective study. 97 patients with a mean age of 65.3 years were classified into control group and surgical treatment group of non-random. 35 patients were in control group and 62 patients who were performed percutaneous vertebroplasty or balloon kyphoplasty in treatment group. X-ray and Magnetic resonance imaging were done at the first and final visit. The grade of disc degeneration above the fractured vertebral was confirmed by evaluation of bony oedema in the fat suppressed sequences and T2-weighted image of magnetic resonance imaging. The height of degenerative disc was measured on X-ray film. RESULTS: All patients were followed up two years after the first visit and the follow-up rate was 90.7% (88/97. The incidence of degeneration of adjacent disc above the fractured vertebral was 29.0% (9/31 in control group and 52.6% (30/57 in treatment group. It presented a statistically significant difference between two groups about the incidence of adjacent disc degeneration (P=0.033. The percentage of adjacent disc height reduction in control group was 13.5% and 17.6% in treatment group. Statistically significant difference of VAS score and ODI was not found between the first evaluation postoperatively and the final follow-up in treatment group (P>0.05. CONCLUSIONS: Disc degeneration adjacent to the fractured vertebral is accelerated by VP and BK procedures in the early stage, but clinical outcomes has not been weakened even in the presence of accelerated disc degeneration.

  2. Comparison of the effect of posterior lumbar interbody fusion with pedicle screw fixation and interspinous fixation on the stiffness of adjacent segments

    Institute of Scientific and Technical Information of China (English)

    LI Chun-de; SUN Hao-lin; LU Hong-zhang

    2013-01-01

    Background Adjacent segment degeneration could seriously affect the long-term prognosis of lumbar fusion.Dynamicfixation such as the interspinous fixation,which is characterized by retaining the motion function of the spinal segment,has obtained satisfactory short-term effects in the clinical setting.But there are few reports about the biomechanicalexperiments on whether dynamic fixation could prevent adjacent segment degeneration.Methods The surgical segments of all 23 patients were L4/5.Thirteen patients with disc herniation of L4/5 underwentWallis implantation surgery,and 10 patients with spinal stenosis of L4/5 underwent posterior lumbar interbody fusion(PLIF).L3-S1 segmental stiffness and displacement were measured by a spine stiffness gauge (SSG) device duringsurgery when the vertebral plate was exposed or during spinal decompression or internal fixation.Five fresh,frozencadavers were used in the self control experiment,which was carried out in four steps:exposure of the vertebral plate,decompression of the spinal canal,implantation of a Wallis fixing device,and PLIF of L4/5 after removing the Wallis fixingdevice.Then,L3-S1 segment stiffness was measured by an SSG device.Results The experiments showed that the average stiffness of the L4/5 segment was (37.1±8.9) N/mm after exposure of the vertebral plate,while after spinal decompression,the average stiffness fell to (26.2±7.1) N/mm,decreasing by 25.8% (P <0.05).For the adjacent segments L3/4 and L5/S1,their stiffness showed no significant difference between the L4/5 segment decompression and the exposure of the vertebral plate (P >0.05).After Wallis implantation of L4/5,the stiffness of the cephalic adjacent segment L3/4 was (45.8±10.7) N/mm,which was 20.5% more than that after the exposure of the vertebral plate (P <0.05); after L4/5 PLIF surgery,the stiffness of L3/4 was (35.3±10.7) N/mm and was decreased by 12.4% more than that after the exposure of the vertebral plate (P <0.05).The

  3. Posterior lumbar dynamic stabilization instead of arthrodesis for symptomatic adjacent-segment degenerative stenosis: description of a novel technique.

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    Mashaly, Hazem; Paschel, Erin E; Khattar, Nicolas K; Goldschmidt, Ezequiel; Gerszten, Peter C

    2016-01-01

    OBJECTIVE The development of symptomatic adjacent-segment disease (ASD) is a well-recognized consequence of lumbar fusion surgery. Extension of a fusion to a diseased segment may only lead to subsequent adjacent-segment degeneration. The authors report the use of a novel technique that uses dynamic stabilization instead of arthrodesis for the surgical treatment of symptomatic ASD following a prior lumbar instrumented fusion. METHODS A cohort of 28 consecutive patients was evaluated who developed symptomatic stenosis immediately adjacent to a previous lumbar instrumented fusion. All patients had symptoms of neurogenic claudication refractory to nonsurgical treatment and were surgically treated with decompression and dynamic stabilization instead of extending the fusion construct using a posterior lumbar dynamic stabilization system. Preoperative symptoms, visual analog scale (VAS) pain scores, and perioperative complications were recorded. Clinical outcome was gauged by comparing VAS scores prior to surgery and at the time of last follow-up. RESULTS The mean follow-up duration was 52 months (range 17-94 months). The mean interval from the time of primary fusion surgery to the dynamic stabilization surgery was 40 months (range 10-96 months). The mean patient age was 51 years (range 29-76 years). There were 19 (68%) men and 9 (32%) women. Twenty-three patients (82%) presented with low-back pain at time of surgery, whereas 24 patients (86%) presented with lower-extremity symptoms only. Twenty-four patients (86%) underwent operations that were performed using single-level dynamic stabilization, 3 patients (11%) were treated at 2 levels, and 1 patient underwent 3-level decompression and dynamic stabilization. The most commonly affected and treated level (46%) was L3-4. The mean preoperative VAS pain score was 8, whereas the mean postoperative score was 3. No patient required surgery for symptomatic degeneration rostral to the level of dynamic stabilization during the

  4. The Interspinous Spacer: A New Posterior Dynamic Stabilization Concept for Prevention of Adjacent Segment Disease

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    Antoine Nachanakian

    2013-01-01

    Full Text Available Introduction. Posterior Dynamic stabilization using the interspinous spacer device is a known to be used as an alternative to rigid fusion in neurogenic claudication patients in the absence of macro instability. Actually, it plays an important in the management of adjacent segment disease in previously fused lumbar spine. Materials and Method. We report our experience with posterior dynamic stabilization using an interspinous spacer. 134 cases performed in our institution between September 2008 and August 2012 with different lumbar spine pathologies. The ages of our patients were between 40 and 72 years, with a mean age of 57 years. After almost 4 years of follow up in our patient and comparing their outcome to our previous serious we found that in some case the interspinous distracter has an important role not only in the treatment of adjacent segment disease but also in its prevention. Results and Discussion. Clinical improvement was noted in ISD-treated patients, with high satisfaction rate. At first, radicular pain improves with more than 3/10 reduction of the mean score on visual analog scale (VAS. In addition, disability score as well as disc height and lordotic angle showed major improvement at 3 to 6 months post operatively. And, no adjacent segment disease was reported in the patient operated with interspinous spacer. Conclusion. The interspinous spacer is safe and efficient modality to be used not only as a treatment of adjacent segment disease but also as a preventive measure in patients necessitating rigid fusion.

  5. Pelvic incidence-lumbar lordosis mismatch predisposes to adjacent segment disease after lumbar spinal fusion.

    Science.gov (United States)

    Rothenfluh, Dominique A; Mueller, Daniel A; Rothenfluh, Esin; Min, Kan

    2015-06-01

    Several risk factors and causes of adjacent segment disease have been debated; however, no quantitative relationship to spino-pelvic parameters has been established so far. A retrospective case-control study was carried out to investigate spino-pelvic alignment in patients with adjacent segment disease compared to a control group. 45 patients (ASDis) were identified that underwent revision surgery for adjacent segment disease after on average 49 months (7-125), 39 patients were selected as control group (CTRL) similar in the distribution of the matching variables, such as age, gender, preoperative degenerative changes, and numbers of segments fused with a mean follow-up of 84 months (61-142) (total n = 84). Several radiographic parameters were measured on pre- and postoperative radiographs, including lumbar lordosis measured (LL), sacral slope, pelvic incidence (PI), and tilt. Significant differences between ASDis and CTRL groups on preoperative radiographs were seen for PI (60.9 ± 10.0° vs. 51.7 ± 10.4°, p = 0.001) and LL (48.1 ± 12.5° vs. 53.8 ± 10.8°, p = 0.012). Pelvic incidence was put into relation to lumbar lordosis by calculating the difference between pelvic incidence and lumbar lordosis (∆PILL = PI-LL, ASDis 12.5 ± 16.7° vs. CTRL 3.4 ± 12.1°, p = 0.001). A cutoff value of 9.8° was determined by logistic regression and ROC analysis and patients classified into a type A (∆PILL lordosis mismatch. In type A spino-pelvic alignment, 25.5 % of patients underwent revision surgery for adjacent segment disease, whereas 78.3 % of patients classified as type B alignment had revision surgery. Classification of patients into type A and B alignments yields a sensitivity for predicting adjacent segment disease of 71 %, a specificity of 81 % and an odds ratio of 10.6. In degenerative disease of the lumbar spine a high pelvic incidence with diminished lumbar lordosis seems to predispose to adjacent segment disease. Patients with such pelvic incidence

  6. CNTF induces regeneration of cone outer segments in a rat model of retinal degeneration.

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    Yiwen Li

    Full Text Available BACKGROUND: Cone photoreceptors are responsible for color and central vision. In the late stage of retinitis pigmentosa and in geographic atrophy associated with age-related macular degeneration, cone degeneration eventually causes loss of central vision. In the present work, we investigated cone degeneration secondary to rod loss in the S334ter-3 transgenic rats carrying the rhodopsin mutation S334ter. METHODOLOGY/PRINCIPAL FINDINGS: Recombinant human ciliary neurotrophic factor (CNTF was delivered by intravitreal injection to the left eye of an animal, and vehicle to the right eye. Eyes were harvested 10 days after injection. Cone outer segments (COS, and cell bodies were identified by staining with peanut agglutinin and cone arrestin antibodies in whole-mount retinas. For long-term treatment with CNTF, CNTF secreting microdevices were implanted into the left eyes at postnatal day (PD 20 and control devices into the right eyes. Cone ERG was recorded at PD 160 from implanted animals. Our results demonstrate that an early sign of cone degeneration is the loss of COS, which concentrated in many small areas throughout the retina and is progressive with age. Treatment with CNTF induces regeneration of COS and thus reverses the degeneration process in early stages of cone degeneration. Sustained delivery of CNTF prevents cones from degeneration and helps them to maintain COS and light-sensing function. CONCLUSIONS/SIGNIFICANCE: Loss of COS is an early sign of secondary cone degeneration whereas cell death occurs much later. At early stages, degenerating cones are capable of regenerating outer segments, indicating the reversal of the degenerative process. Sustained delivery of CNTF preserves cone cells and their function. Long-term treatment with CNTF starting at early stages of degeneration could be a viable strategy for preservation of central vision for patients with retinal degenerations.

  7. The biomechanical effect of postoperative hypolordosis in instrumented lumbar fusion on instrumented and adjacent spinal segments.

    Science.gov (United States)

    Umehara, S; Zindrick, M R; Patwardhan, A G; Havey, R M; Vrbos, L A; Knight, G W; Miyano, S; Kirincic, M; Kaneda, K; Lorenz, M A

    2000-07-01

    Change in lumbar lordosis was measured in patients that had undergone posterolateral lumbar fusions using transpedicular instrumentation. The biomechanical effects of postoperative lumbar malalignment were measured in cadaveric specimens. To determine the extent of postoperative lumbar sagittal malalignment caused by an intraoperative kneeling position with 90 degrees of hip and knee flexion, and to assess its effect on the mechanical loading of the instrumented and adjacent segments. The importance of maintaining the baseline lumbar lordosis after surgery has been stressed in the literature. However, there are few objective data to evaluate whether postoperative hypolordosis in the instrumented segments can increase the likelihood of junctional breakdown. Segmental lordosis was measured on preoperative standing, intraoperative prone, and postoperative standing radiographs. In human cadaveric spines, a lordosis loss of up to 8 degrees was created across L4-S1 using calibrated transpedicular devices. Specimens were tested in extension and under axial loading in the upright posture. In patients who underwent L4-S1 fusions, the lordosis within the fusion decreased by 10 degrees intraoperatively and after surgery. Postoperative lordosis in the proximal (L2-L3 and L3-L4) segments increased by 2 degrees each, as compared with the preoperative measures. Hypolordosis in the instrumented segments increased the load across the posterior transpedicular devices, the posterior shear force, and the lamina strain at the adjacent level. Hypolordosis in the instrumented segments caused increased loading of the posterior column of the adjacent segments. These biomechanical effects may explain the degenerative changes at the junctional level that have been observed as long-term consequences of lumbar fusion.

  8. SNAREs Interact with Retinal Degeneration Slow and Rod Outer Segment Membrane Protein-1 during Conventional and Unconventional Outer Segment Targeting.

    Science.gov (United States)

    Zulliger, Rahel; Conley, Shannon M; Mwoyosvi, Maggie L; Stuck, Michael W; Azadi, Seifollah; Naash, Muna I

    2015-01-01

    Mutations in the photoreceptor protein peripherin-2 (also known as RDS) cause severe retinal degeneration. RDS and its homolog ROM-1 (rod outer segment protein 1) are synthesized in the inner segment and then trafficked into the outer segment where they function in tetramers and covalently linked larger complexes. Our goal is to identify binding partners of RDS and ROM-1 that may be involved in their biosynthetic pathway or in their function in the photoreceptor outer segment (OS). Here we utilize several methods including mass spectrometry after affinity purification, in vitro co-expression followed by pull-down, in vivo pull-down from mouse retinas, and proximity ligation assay to identify and confirm the SNARE proteins Syntaxin 3B and SNAP-25 as novel binding partners of RDS and ROM-1. We show that both covalently linked and non-covalently linked RDS complexes interact with Syntaxin 3B. RDS in the mouse is trafficked from the inner segment to the outer segment by both conventional (i.e., Golgi dependent) and unconventional secretory pathways, and RDS from both pathways interacts with Syntaxin3B. Syntaxin 3B and SNAP-25 are enriched in the inner segment (compared to the outer segment) suggesting that the interaction with RDS/ROM-1 occurs in the inner segment. Syntaxin 3B and SNAP-25 are involved in mediating fusion of vesicles carrying other outer segment proteins during outer segment targeting, so could be involved in the trafficking of RDS/ROM-1.

  9. Adjacent segment disease after anterior cervical decompression and fusion: analysis of risk factors on X-ray and magnetic resonance imaging

    Institute of Scientific and Technical Information of China (English)

    Zhao Yanbin; Sun Yu; Zhou Feifei; Wang Shaobo; Zhang Fengshan; Pan Shengfa

    2014-01-01

    Background Adjacent segment disease (ASD) is common after cervical fusion.The aim of this study was to evaluate the risk factors for ASD on X-ray and magnetic resonance imaging (MRI).Methods Patients included in this study had received revision surgeries after developing symptomatic ASD following anterior decompression and fusion.A control group that had not developed ASD was matched 1:1 by follow-up time and fusion segments.Plate-to-disc distances (PDDs),developmental cervical canal stenosis on X-ray,cervical disc degeneration grading,and cervical disc bulge impingements on preoperative MRI were measured and compared between the ASD group and the control group.Results Thirty-four patients with complete radiographic data were included in the ASD group.The causative segments of ASD included nine cases of C3-4,18 cases of C4-5,three cases of C5-6,and four cases of C6-7.The ASD occurred at the upper adjacent segments in 26 patients and at the lower adjacent segments in eight patients.PDD distributions were similar between the ASD group and the control group.Developmental cervical canal stenosis was a risk factor for ASD,with an odd ratio value of 2.88.Preoperative cervical disc degenerations on MRI were similar between the ASD group and the control group.In the upper-level ASD group,the disc bulge impingement was (19.7±9.7)%,which was significantly higher than that of the control group of (11.8±4.8)%.Conclusions ASD was more likely to develop above the index level of fusion.Developmental cervical canal stenosis and greater disc bulge impingement may be risk factors for the development of ASD.

  10. Repeated adjacent segment diseases and fractures in osteoporotic patients: a case report

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    Chen HY

    2016-07-01

    Full Text Available Hsin-Yao Chen,1 Chiu-Liang Chen,1,2 Wei-Liang Chen3 1Department of Orthopedic Surgery, Changhua Christian Hospital, Changhua City, 2Liberal Arts Center of Da Yeh University, Dacun Township, Changhua County, Taiwan; 3Department of Clinical Image, Changhua Christian Hospital, Changhua City, Changhua County, Taiwan Background: Pedicle screw instrumentation for treating spinal disorder is becoming increasingly widespread. Many studies have advocated its use to facilitate rigid fixation for spine; however, adjacent segmental disease is a known complication. Instrumented fusion for osteoporotic spines remains a significant challenge for spine surgeons. Prophylactic vertebroplasty for adjacent vertebra has been reported to reduce the complications of junctional compression fractures but has raised a new problem of vertebral subluxation. This case report is a rare and an extreme example with many surgical complications caused by repeated instrumented fusion for osteoporotic spine in a single patient. This patient had various complications including adjacent segmental disease, vertebral subluxation, and junctional fractures on radiographs and magnetic resonance images.Case presentation: An 81-year-old Taiwanese woman underwent decompression and instrumented fusion of L4-L5 in Taiwan 10 years ago. Due to degenerative spinal stenosis of L3-L4 and L2-L3, she had decompression with instrumented fusion from L5 to L1 at the previous hospital. However, catastrophic vertebral subluxations with severe neurologic compromise occurred, and she underwent salvage surgeries twice with prolonged instrumented fusion from L5 to T2. The surgeries did not resolve her problems of spinal instability and neurologic complications. Eventually, the patient remained with a Frankel Grade C spinal cord injury.Conclusion: Adjacent segmental disease, junctional fracture, and vertebral subluxation are familiar complications following instrumented spinal fusion surgeries for

  11. Mind the edge! The role of adjacency matrix degeneration in maximum entropy weighted network models

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    Sagarra, Oleguer; Díaz-Guilera, Albert

    2015-01-01

    Complex network null models based on entropy maximization are becoming a powerful tool to characterize and analyze data from real systems. However, it is not easy to extract good and unbiased information from these models: A proper understanding of the nature of the underlying events represented in them is crucial. In this paper we emphasize this fact stressing how an accurate counting of configurations compatible with given constraints is fundamental to build good null models for the case of networks with integer valued adjacency matrices constructed from aggregation of one or multiple layers. We show how different assumptions about the elements from which the networks are built give rise to distinctively different statistics, even when considering the same observables to match those of real data. We illustrate our findings by applying the formalism to three datasets using an open-source software package accompanying the present work and demonstrate how such differences are clearly seen when measuring networ...

  12. Older literature review of increased risk of adjacent segment degeneration with instrumented lumbar fusions

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    Nancy E Epstein

    2016-01-01

    Conclusions: Too many studies assume that TLIF, PLIF, and even PLF instrumented fusions are the "gold standard of care" for dealing with degenerative disease of the lumbar spine without documented instability. It is time to correct that assumption, and reassess the older literature along with the new to confirm that decompression alone and noninstrumented fusion avoid significant morbidity and even potentially mortality attributed to unnecessary instrumentation.

  13. Abnormal photoreceptor outer segment development and early retinal degeneration in kif3a mutant zebrafish.

    Science.gov (United States)

    Raghupathy, Rakesh K; Zhang, Xun; Alhasani, Reem H; Zhou, Xinzhi; Mullin, Margaret; Reilly, James; Li, Wenchang; Liu, Mugen; Shu, Xinhua

    2016-08-01

    Photoreceptors are highly specialized sensory neurons that possess a modified primary cilium called the outer segment. Photoreceptor outer segment formation and maintenance require highly active protein transport via a process known as intraflagellar transport. Anterograde transport in outer segments is powered by the heterotrimeric kinesin II and coordinated by intraflagellar transport proteins. Here, we describe a new zebrafish model carrying a nonsense mutation in the kinesin II family member 3A (kif3a) gene. Kif3a mutant zebrafish exhibited curved body axes and kidney cysts. Outer segments were not formed in most parts of the mutant retina, and rhodopsin was mislocalized, suggesting KIF3A has a role in rhodopsin trafficking. Both rod and cone photoreceptors degenerated rapidly between 4 and 9 days post fertilization, and electroretinography response was not detected in 7 days post fertilization mutant larvae. Loss of KIF3A in zebrafish also resulted in an intracellular transport defect affecting anterograde but not retrograde transport of organelles. Our results indicate KIF3A plays a conserved role in photoreceptor outer segment formation and intracellular transport.

  14. MR abnormalities of the intervertebral disks and adjacent bone marrow as predictors of segmental instability of the lumbar spine

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    Braem, J.; Zanetti, M.; Hodler, J. [Orthopedic University Clinic Balgrist, Zurich (Switzerland). Dept. of Diagnostic Radiology; Min, K. [Orthopedic University Clinic Balgrist, Zurich (Switzerland). Dept. of Orthopedic Surgery

    1998-01-01

    Purpose: To assess whether MR abnormalities of the intervertebral disks and adjacent bone marrow can predict segmental instability of the lumbar spine as diagnosed on functional radiographs. Material and Methods: A consecutive review was made of 60 patients examined with MR imaging and with lateral flexion and extension views of the lumbar spine. Sagittal T1- and T2-weighted images were evaluated blindly with regard to abnormalities of the intervertebral disk and the adjacent bone marrow. Segmental instability was diagnosed when a.p. translation of 3 mm or more was present on the functional radiographs. Moreover, the presence of osteophytes was evaluated on lateral standard radiographs. Results: Of a total of 300 segments, 32 (10.7%) were unstable. Anular tears were the most relevant MR finding. Their sensitivity, specificity, and positive and negative predictive values for segmental instability were 18.8%, 97.0%, 42.9% and 90.9%. The corresponding values for traction osteophytes were 12.5%, 98.1%, 44.4% and 90.4%. Abnormalities of bone marrow were not significantly related to segmental instability (p=0.35). Conclusion: Functional radiographs should be considered in patients with anular tears or traction osteophytes. No correlation was found between segmental instability and abnormalities of bone marrow adjacent to the endplates. (orig.).

  15. Finite element analysis of weightbath hydrotraction treatment of degenerated lumbar spine segments in elastic phase.

    Science.gov (United States)

    Kurutz, M; Oroszváry, L

    2010-02-10

    3D finite element models of human lumbar functional spinal units (FSU) were used for numerical analysis of weightbath hydrotraction therapy (WHT) applied for treating degenerative diseases of the lumbar spine. Five grades of age-related degeneration were modeled by material properties. Tensile material parameters of discs were obtained by parameter identification based on in vivo measured elongations of lumbar segments during regular WHT, compressive material constants were obtained from the literature. It has been proved numerically that young adults of 40-45 years have the most deformable and vulnerable discs, while the stability of segments increases with further aging. The reasons were found by analyzing the separated contrasting effects of decreasing incompressibility and increasing hardening of nucleus, yielding non-monotonous functions of stresses and deformations in terms of aging and degeneration. WHT consists of indirect and direct traction phases. Discs show a bilinear material behaviour with higher resistance in indirect and smaller in direct traction phase. Consequently, although the direct traction load is only 6% of the indirect one, direct traction deformations are 15-90% of the indirect ones, depending on the grade of degeneration. Moreover, the ratio of direct stress relaxation remains equally about 6-8% only. Consequently, direct traction controlled by extra lead weights influences mostly the deformations being responsible for the nerve release; while the stress relaxation is influenced mainly by the indirect traction load coming from the removal of the compressive body weight and muscle forces in the water. A mildly degenerated disc in WHT shows 0.15mm direct, 0.45mm indirect and 0.6mm total extension; 0.2mm direct, 0.6mm indirect and 0.8mm total posterior contraction. A severely degenerated disc exhibits 0.05mm direct, 0.05mm indirect and 0.1mm total extension; 0.05mm direct, 0.25mm indirect and 0.3mm total posterior contraction. These

  16. Differential gene expression in proximal and distal nerve segments of rats with sciatic nerve injury during Wallerian degeneration

    Institute of Scientific and Technical Information of China (English)

    Nan Jiang; Huaiqin Li; Yi Sun; Dexin Yin; Qin Zhao; Shusen Cui; Dengbing Yao

    2014-01-01

    Wallerian degeneration is a subject of major interest in neuroscience. A large number of genes are differentially regulated during the distinct stages of Wallerian degeneration: transcription factor activation, immune response, myelin cell differentiation and dedifferentiation. Although gene expression responses in the distal segment of the sciatic nerve after peripheral nerve injury are known, differences in gene expression between the proximal and distal segments remain unclear. In the present study in rats, we used microarrays to analyze changes in gene expression, biological processes and signaling pathways in the proximal and distal segments of sciatic nerves under-going Wallerian degeneration. More than 6,000 genes were differentially expressed and 20 types of expression tendencies were identiifed, mainly between proximal and distal segments at 7-14 days after injury. The differentially expressed genes were those involved in cell differentiation, cytokinesis, neuron differentiation, nerve development and axon regeneration. Furthermore, 11 biological processes were represented, related to responses to stimuli, cell apoptosis, inlfammato-ry response, immune response, signal transduction, protein kinase activity, and cell proliferation. Using real-time quantitative PCR, western blot analysis and immunohistochemistry, microarray data were veriifed for four genes: aquaporin-4, interleukin 1 receptor-like 1, matrix metallopro-teinase-12 and periaxin. Our study identiifes differential gene expression in the proximal and distal segments of a nerve during Wallerian degeneration, analyzes dynamic biological changes of these genes, and provides a useful platform for the detailed study of nerve injury and repair during Wallerian degeneration.

  17. Correlation between cervical lordosis and adjacent segment pathology after anterior cervical spinal surgery.

    Science.gov (United States)

    Lee, Soo Eon; Jahng, Tae-Ahn; Kim, Hyun Jib

    2015-12-01

    To evaluate the incidence and risk factors for adjacent segment pathology (ASP) after anterior cervical spinal surgery. Fourteen patients (12 male, mean age 47.1 years) who underwent single-level cervical disk arthroplasty (CDA group) and 28 case-matched patients (24 male, mean age 53.6 years) who underwent single-level anterior cervical discectomy and fusion (ACDF group) were included. Presence of radiologic ASP (RASP) was based on observed changes in anterior osteophytes, disks, and calcification of the anterior longitudinal ligament on lateral radiographs. The mean follow-up period was 43.4 months in the CDA group and 44.6 months in the ACDF group. At final follow-up, ASP was observed in 5 (35.7%) CDA patients and 16 (57.1%) ACDF patients (p = 0.272). The interval between surgery and ASP development was 33.8 months in the CDA group and 16.3 months in the ACDF group (p = 0.046). The ASP risk factor analysis indicated postoperative cervical angle at C3-7 being more lordotic in non-ASP patients in both groups. Restoration of lordosis occurred in the CDA group regardless of the presence of ASP, but heterotopic ossification development was associated with the presence of ASP in the CDA group. And the CDA group had significantly greater clinical improvements than those in the ACDF group when ASP was present. In both CDA and ACDF patients, RASP developed, but CDA was associated with a delay in ASP development. A good clinical outcome was expected in CDA group, even when ASP developed. Restoration of cervical lordosis was an important factor in anterior cervical spine surgery.

  18. 胸腰段陈旧性压缩性骨折患者椎体变形与相邻椎间盘退变的相关性%Correlation of vertebral body deformity and adjacent disc degeneration in patients with old thoracolumbar compression fractures

    Institute of Scientific and Technical Information of China (English)

    崔运能; 李绍林; 赵银霞; 岑黄

    2015-01-01

    Objective To assess the correlation between vertebral body deformity and degeneration of the adjacent intervertebral discs in patients with old thoracolumbar compression fractures. Methods Seventy-one patients who had been conservatively treated after single segment thoracolumbar compression fractures between April, 2011 and May, 2014 were enrolled in this study. Both radiographic and magnetic resonance (MR) images of the thoracolumbar segment were obtained. The involved vertebral body deformity was rated on radiography according to the Genant criterion, and the degeneration of the adjacent cephalic and caudal discs was assessed on MR images using the Oner and Pfirrmann classification schemes, respectively. The relationship between vertebral body deformity and adjacent disc changes was assessed using correlation analysis, and the changes in the adjacent cranial and caudal discs was compared. Results The Genant classification of the involved vertebral bodies was moderately correlated with Oner morphological scores (r=0.48, P0.05). The Oner classification of the adjacent cephalic discs was higher than that of the adjacent caudal discs (P0.05),变形椎体相邻头侧的椎间盘Oner分度较相邻尾侧椎间盘高(P0.05)。结论胸腰段椎体压缩性骨折主要影响相邻头侧椎间盘的形态,两者严重程度相一致,而相邻尾侧椎间盘不受影响。

  19. The Correlation between Relation of Anterior Cervical Plate Position and Adjacent Level Degeneration%颈前路钢板固定位置与相邻节段退变之间关系的研究

    Institute of Scientific and Technical Information of China (English)

    冯虎; 马志兵; 齐祥如; 袁峰; 郭开今

    2011-01-01

    Objective To study adjacent level degeneration after anterior cervical spine fusion with a plate and its relation to the plate position.Methods Totally 165 patients were received anterior cervical spine fusion with plates months, who had a bony fusion wholly.The cephalad and caudal plate to disc distance(PDD) was measured on thepostoperative lateral radiograph and was used to divide the patients into two groups. In group A the PDD was<5mm, and in group B it was>5mm. The severity of the ossification at the two adjacent disc space was classified on a scale ranging from grade 0(no ossification ) to grade 2(complete bridging ). Preoperative, immediate postoperative and 6 to 46 months follow-up radiographs were taken, measured the height of cephalad and caudal adjacent intervertebral and adjacent vertebral body, and then calculated the ratio of intervertebral height to vertebral body height (R), besides, calculated the angle(α)of upper and down endplate gradient of two adjacent disc. Results In cephalad adjacent disc, group A had 53.7% levels developed ossification and 29.8% in group B; compared to caudal adjacent disc, group A and B was 38.5% and 19.7%, respectively. The rate of ossification was higher in group A than in group B, both at two adjacent disc (P<0.05). There was no significant difference between preoperative and postoperative both R ratio and angle α in group A of cephalad adjacent disc (P>0.05), but it was significant decreased when followed up comparing to preoperative and postoperative (P<0.05). The result of R ratio of caudal adjacent disc was similar with cephalad adjacent disc in group A, but angle α was not. There was no significant difference among preoperative, postoperative and following up time both R ratio and angle α in group B of cephalad and caudal adjacent disc (P>0.05).Conclusion Adjacent segments degeneration was one of the common complications after anterior cervical spine fusion. The incidence could be affected

  20. Pelvic incidence-lumbar lordosis mismatch predisposes to adjacent segment disease after lumbar spinal fusion

    National Research Council Canada - National Science Library

    Rothenfluh, Dominique A; Mueller, Daniel A; Rothenfluh, Esin; Min, Kan

    ..., and numbers of segments fused with a mean follow-up of 84 months (61–142) (total n = 84). Several radiographic parameters were measured on pre- and postoperative radiographs, including lumbar lordosis measured (LL...

  1. Concatemeric intermediates of equine herpesvirus type 1 DNA replication contain frequent inversions of adjacent long segments of the viral genome.

    Science.gov (United States)

    Slobedman, B; Simmons, A

    1997-03-17

    In common with other alpha-herpesviruses, the genome of equine herpesvirus type-1 (EHV-1) comprises covalently linked long and short unique sequences of DNA, each flanked by inverted repeats. Equimolar amounts of two genomic isomers, generated by free inversion of the short segment, relative to the long segment, are packaged into EHV-1 virions. In contrast with herpes simplex virus (HSV), inversion of genomic long segments has not been described. In the current work, the structures of high molecular weight intermediates of EHV-1 DNA replication were studied by field inversion gel electrophoresis. It is shown that adjacent long segments of the viral genome are frequently inverted in concatemeric intermediates of EHV-1 DNA replication. Further, like HSV concatemers, high molecular weight intermediates of EHV-1 replication are flanked exclusively by the long segment of the viral genome. Hence, despite the fact that only two, rather than four, isomers of EHV-1 DNA are packaged into virions, the intermediates of EHV-1 DNA replication closely resemble those of herpes simplex virus type 1 in structure. These data have implications relating to the mechanisms involved in packaging of alpha-herpesvirus DNA.

  2. 腰椎融合术后发生邻近节段退行性变的研究进展%Research advance in adjacent segment disease after operation with lumbar fusion

    Institute of Scientific and Technical Information of China (English)

    任伟峰; 刘晋闽; 章明

    2011-01-01

    随着脊柱手术方法的日趋成熟和内固定器械的日新月异,脊柱融合术的成功率有了明显提高.然而术后长期随访并发症也日益引起脊柱外科医师的关注,尤其是融合内固定术后邻近节段退变(adjacent segment degeneration,ASD)的问题变得更为突出,因其可引起临床症状,影响预后,正成为基础和临床研究的热点.本文从ASD发生的机制,影响ASD的因素,ASD的治疗策略,ASD的预防做一综述.%With the development of spinal surgical techniques and internal fixation, the success rate of spinal fusion has been significantly increased. However,the complications by long-term follow-up postoperatively are also increasingly concerned ,especially the adjacent segment degeneration (ASD). It is becoming a hot spot by basic and clinical research. Because they can cause clinical symptoms and influence clinical effects. This article reviewed the mechanisms of ASD, factors of the affecting ASD, treatment of ASD and prevention of ASD.

  3. 计算机辅助的腰椎单节段融合后邻近节段的力学变化研究%Computer assisted analysis in adjacent segment disease after singe-level lumbar fusion

    Institute of Scientific and Technical Information of China (English)

    闫家智; 林欣; 王磊; 崔维; 曾峥

    2011-01-01

    目的 利用有限元分析方法,建立L2-L5多节段腰椎有限元模型,模拟L3-L4后路单节段经椎弓根钉棒固定手术,观察融合后邻近节段L2-L3和L4-L5椎间盘的应力变化.方法 建立A、B、C 3组L2-L5的有限元模型.A组:L3-L4未手术固定,无椎间盘退变;B组:L3-L4手术固定,术前邻近节段无退变;C组:L3-L4手术固定组,术前邻近节段已有退变;在0.3、0.5、1.0、2.0 MPa 4种轴向压力作下,比较各组作为邻近节段的L2-L3椎间盘和L4-L5椎间盘的应力变化.结果 得出A组、B组、C组的L2-L3椎间盘和L4-L5椎间盘最大主应力平均值,经统计学处理结果,L2-L3椎间盘的A组和B组之间在4种受力情况下,应力都无显著性差异,L2-L3椎间盘的A组和C组间及L4-L5椎间盘各组间在4种受力情况下,应力都有显著性差异.结论 单节段后路腰椎固定融合不是引起邻近节段退变的重要原因;但邻近节段的椎间盘如果已经发生退变,则可能是影响形成的重要因素.%Objective To evlutate the biomechanical alterations occuring at the adjacent segment after posterior intertransverse fusion in L3 - L4 segment with the finite element analysis. Methods Three 3D finite element models of the human L2 - L5 segments of Group A, Group B, Group C were established. Group A: uninstrumented fusions, with healthy discs of adjacent segment( L2 - L3, L4 - L5 ), Group B: posterior intertransverse fusion in L3 - L4 segment with healthy discs, GroupC: posterior intertransverse fusion in L3 -L4 segment, with degenerated discs of adjacent segment ( L2 - L3, L4 - L5 ) . The stress on the discs of adjacent segment( L2 - L3, L4 - L5 ) under axial pressure(0.3 MPa, 0.5 MPa, 1.0 MPa, 2.0 MPa) was analysed. Results The stress on the disc L2 - L3 was no statistically significant difficence between Group A and Group B, but there was statistically significant difficence between Group A and Group C;The stress on the disc L3 - L4 was statistically

  4. Síndrome adyacente Síndrome adjacente Adjacent segment disease

    Directory of Open Access Journals (Sweden)

    Gustavo Martin

    2012-06-01

    recovered in both cases. MRI before the first intervention was 83% with Pfirmann IV. AS level: 38% L3-L4, L5-S1: 26%. AS types: lumbar stenosis worsened by monosegmental antero-listhesis in 20 and retro-listhesis in 14; multisegmental stenosis 4, disc herniation 4, crush fracture 4, stenosis without listhesis 4. Period between the 2 surgeries: on average 6 years. CONCLUSION: An incidence of 9.4% of reoperation due to adjacent syndrome makes this disease an important long-term problem, forcing the surgeon to take all the possible steps to avoid this. With the results of this retrospective study we could only say that the segments more likely to develop AS are those with Pfirmann IV on MRI and that the relation VP (20% and PS (80% pre and post-operative should be taken into account to return to the spinal column perfect mechanical condition. Prospective clinical studies are needed for more conclusive results.

  5. Role of major revision spine surgery in recurrent adjacent segment osteoporotic vertebral body fracture: a case report.

    Science.gov (United States)

    Ghani, Imtiaz; Kroeber, Markus

    2012-08-01

    Case report. To report the beneficial effects of kyphoplasty, cement augmentation and extension of posterior instrumentation in a patient with recurrent adjacent segment osteoporotic vertebral body fracture. A 72-year-old lady underwent multiple revision spine surgeries for recurrent adjacent segment osteoporotic vertebral body fracture. The patient underwent four surgeries in 6 years: (1) in 2005, posterior lumbar interbody fusion with stabilization (L4-S1) was done; (2) in August 2010, implants from L4-S1 were removed and revised, transforaminal lumbar interbody fusion was done at L2/L3 and L3/L4 along with pedicle screw stabilization from T12-S1; (3) in September 2011, revision surgery was attempted, wherein a kyphoplasty was done at T12 and the stabilization was extended to T4; (4) again in October 2011, a revision surgery was attempted, wherein a kyphoplasty was done at T5 along with stabilization using pedicular screws in the T2 and T3 vertebrae and lateral mass screws in the C6 vertebra. To current date, the patient is stable with good sagittal and coronal balance and walking pain free without support. The current case demonstrates the need for posterior spinal reconstruction in osteoporotic vertebral collapse. Cement augmentation and extension of posterior instrumentation are both viable techniques that could be used to improve stabilization in the elderly spine.

  6. Pathoanatomic Risk Factors for Instability and Adjacent Segment Disease in Lumbar Spine: How to Use Topping Off?

    Directory of Open Access Journals (Sweden)

    J. Bredow

    2017-01-01

    Full Text Available Purpose. The goal of this review is to identify criteria indicating implantation of hybrid system into lumbar spine and to evaluate general benefits of use. Methods. A systematic review of literature was performed using current randomized clinical trials, reviews, and meta-analyses. Data sources included relevant literature of human studies identified through searches of Medline Library until May 2015. Results. Predisposing factors for Adjacent Segment Disease (ASDi are discussed in literature: laminar horizontalization, insufficiency of fascia thoracolumbalis, facet tropism, and facet sagittalization. Currently there is no evidence for topping off. There are only 12 studies and these have no consistent statements about use of a hybrid system for avoidance of ASDi. Conclusion. Hybrid instrumentation of lumbar spine, either with pedicle-based technique or additional spacer, might possibly prevent ASDi from developing in previously damaged segment adjacent to a fusion. Good clinical data proving effectiveness of this new implant technique is as yet unavailable. Thus, currently one must speak of an unevaluated procedure. Various radiological classifications can assist in making a reliable decision as to whether hybrid instrumentation is an appropriate choice of therapy. Pathoanatomical conditions of facet joints and laminae as well as preservation of sagittal balance must also be considered.

  7. Loosely coupled level sets for retinal layers and drusen segmentation in subjects with dry age-related macular degeneration

    Science.gov (United States)

    Novosel, Jelena; Wang, Ziyuan; de Jong, Henk; Vermeer, Koenraad A.; van Vliet, Lucas J.

    2016-03-01

    Optical coherence tomography (OCT) is used to produce high-resolution three-dimensional images of the retina, which permit the investigation of retinal irregularities. In dry age-related macular degeneration (AMD), a chronic eye disease that causes central vision loss, disruptions such as drusen and changes in retinal layer thicknesses occur which could be used as biomarkers for disease monitoring and diagnosis. Due to the topology disrupting pathology, existing segmentation methods often fail. Here, we present a solution for the segmentation of retinal layers in dry AMD subjects by extending our previously presented loosely coupled level sets framework which operates on attenuation coefficients. In eyes affected by AMD, Bruch's membrane becomes visible only below the drusen and our segmentation framework is adapted to delineate such a partially discernible interface. Furthermore, the initialization stage, which tentatively segments five interfaces, is modified to accommodate the appearance of drusen. This stage is based on Dijkstra's algorithm and combines prior knowledge on the shape of the interface, gradient and attenuation coefficient in the newly proposed cost function. This prior knowledge is incorporated by varying the weights for horizontal, diagonal and vertical edges. Finally, quantitative evaluation of the accuracy shows a good agreement between manual and automated segmentation.

  8. Segmentation and quantification of retinal lesions in age-related macular degeneration using polarization-sensitive optical coherence tomography.

    Science.gov (United States)

    Baumann, Bernhard; Gotzinger, Erich; Pircher, Michael; Sattmann, Harald; Schuutze, Christopher; Schlanitz, Ferdinand; Ahlers, Christian; Schmidt-Erfurth, Ursula; Hitzenberger, Christoph K

    2010-01-01

    We present polarization-sensitive optical coherence tomography (PS-OCT) for quantitative assessment of retinal pathologies in age-related macular degeneration (AMD). On the basis of the polarization scrambling characteristics of the retinal pigment epithelium, novel segmentation algorithms were developed that allow one to segment pathologic features such as drusen and atrophic zones in dry AMD as well as to determine their dimensions. Results from measurements in the eyes of AMD patients prove the ability of PS-OCT for quantitative imaging based on the retinal features polarizing properties. Repeatability measurements were performed in retinas diagnosed with drusen and geographic atrophy in order to evaluate the performance of the described methods. PS-OCT appears as a promising imaging modality for three-dimensional retinal imaging and ranging with additional contrast based on the structures' tissue-inherent polarization properties.

  9. Segmentation and quantification of retinal lesions in age-related macular degeneration using polarization-sensitive optical coherence tomography

    Science.gov (United States)

    Baumann, Bernhard; Götzinger, Erich; Pircher, Michael; Sattmann, Harald; Schütze, Christopher; Schlanitz, Ferdinand; Ahlers, Christian; Schmidt-Erfurth, Ursula; Hitzenberger, Christoph K.

    2010-11-01

    We present polarization-sensitive optical coherence tomography (PS-OCT) for quantitative assessment of retinal pathologies in age-related macular degeneration (AMD). On the basis of the polarization scrambling characteristics of the retinal pigment epithelium, novel segmentation algorithms were developed that allow one to segment pathologic features such as drusen and atrophic zones in dry AMD as well as to determine their dimensions. Results from measurements in the eyes of AMD patients prove the ability of PS-OCT for quantitative imaging based on the retinal features polarizing properties. Repeatability measurements were performed in retinas diagnosed with drusen and geographic atrophy in order to evaluate the performance of the described methods. PS-OCT appears as a promising imaging modality for three-dimensional retinal imaging and ranging with additional contrast based on the structures' tissue-inherent polarization properties.

  10. 2D segmentation of intervertebral discs and its degree of degeneration from T2-weighted magnetic resonance images

    Science.gov (United States)

    Castro-Mateos, Isaac; Pozo, José Maria; Lazary, Aron; Frangi, Alejandro F.

    2014-03-01

    Low back pain (LBP) is a disorder suffered by a large population around the world. A key factor causing this illness is Intervertebral Disc (IVD) degeneration, whose early diagnosis could help in preventing this widespread condition. Clinicians base their diagnosis on visual inspection of 2D slices of Magnetic Resonance (MR) images, which is subject to large interobserver variability. In this work, an automatic classification method is presented, which provides the Pfirrmann degree of degeneration from a mid-sagittal MR slice. The proposed method utilizes Active Contour Models, with a new geometrical energy, to achieve an initial segmentation, which is further improved using fuzzy C-means. Then, IVDs are classified according to their degree of degeneration. This classification is attained by employing Adaboost on five specific features: the mean and the variance of the probability map of the nucleus using two different approaches and the eccentricity of the fitting ellipse to the contour of the IVD. The classification method was evaluated using a cohort of 150 intervertebral discs assessed by three experts, resulting in a mean specificity (93%) and sensitivity (83%) similar to the one provided by every expert with respect to the most voted value. The segmentation accuracy was evaluated using the Dice Similarity Index (DSI) and Root Mean Square Error (RMSE) of the point-to-contour distance. The mean DSI ± 2 standard deviation was 91:7% ±5:6%, the mean RMSE was 0:82mm and the 95 percentile was 1:36mm. These results were found accurate when compared to the state-of-the-art.

  11. 前路减压植骨融合术后颈椎相邻节段生物力学变化%Biomechanical changes of the adjacent segments after anterior cervical decompression and fusion

    Institute of Scientific and Technical Information of China (English)

    尹飞; 郭丽; 朱庆三; 赵东旭; 巩固; 李然; 赵昆池; 王迎智

    2013-01-01

    Objective To study the biomechanical changes of the adjacent segments after anterior cervical decompression and fusion (ACDF).Methods EB composite resin was used to mimic the fuion effect after anterior cervical decompression.The motion range and biomechanical changes of the adjacent segments were measured.Results Under the same torque of 2.0 Nm,the motion range of the adjacent segments was from 4.3 to 8.0 degrees,which was not significantly different from that before fusion (P >0.05).Increasing the torque gradually to let the samples reach their normal range of motion,the range of motion of the adjacent segments increased significantly.There are significant differences of them after and before fusion (P < 0.05).Conclusion If people keep the normal range of motion of cervical spine after ACDF,their adjacent segment's movement will increase significantly.This might be the main cause of the degeneration after fusion.By limiting the neck movement can reduce,or even avoid postoperative degeneration.%目的 观察颈椎前路减压植骨融合术后相邻节段生物力学变化.方法 采用EB复合树脂黏合的方法模拟颈椎前路减压植骨术后融合的效果,检测颈椎融合前、后相邻节段运动范围及生物力学的变化.结果 在2.0 Nm力矩不变的情况下,融合节段相邻间隙的运动范围为4.3°~8.0°,与融合前比较差异无统计学意义(P>0.05);加大力矩使融合后的颈椎尽量达到术前正常运动范围时融合节段相邻间隙运动范围明显增加,与融合前比较差异有统计学意义(P<0.05).结论 颈椎融合术后如果仍要达到术前正常的运动范围,其相邻节段的运动范围明显增加,这可能是造成其退变的主要原因.限制颈部术后活动可以减少、甚至避免术后退变的发生.

  12. 腰椎融合后邻近节段影像学评估方法的应用随访%Follow-up application of imaging evaluation on adjacent lumbar segment after instrumented posterior spinal fusion

    Institute of Scientific and Technical Information of China (English)

    吴超; 魏剑; 王清; 谭伦; 黄迅; 唐玉湖

    2011-01-01

    背景:目前多数研究只分析了脊柱融合治疗紧邻融合区域头尾侧节段的术后改变,未对其他紧邻内固定的未作融合节段进行对照研究.目的:探讨腰椎邻近节段的测量方法,对腰椎后外侧融合后邻近节段的改变进行长期随访影像学评估.方法:选取尸体骨架6具,以不同投照方式和标本位置行腰椎侧位数字化标准X射线片共计42次(每具标本投照7次).随访57例腰椎后外侧融合患者,随访时间1.5~4年,拍摄融合前及末次随访时的数字化标准X射线片,所有资料用失真代偿X射线分析法测量椎体间矢状角度、椎间盘高度、椎体间前后移位.结果与结论:失真代偿X射线分析法测量邻近节段矢状曲度、椎间盘高度、椎体间前后移位时,不同投照方式比较差异均无显著性意义(P > 0.05).固定节段尾侧椎体间未发现显著的影像学改变,固定节段头侧的多个椎体间矢状角度、椎间盘高度均有明显的改变.提示腰椎后外侧融合后影像学的改变提示固定节段头侧多个椎间盘加速退变.%BACKGROUND: Now, most studies related to adjacent segment degeneration only analyze the changes of motion segmentsabove and below the fusion. There were no controlled studies on adjacent segments to all the other unfused segments afterinstrumented posterior fusion.OBJECTIVE: To study measurement of adjacent lumbar segments and evaluate long-term radiographic changes in all adjacentlumbar segments after instrumented posterolateral lumbar fusion.METHODS: Totally 42 digitized radiographs of lateral lumbar spine from 6 corpse skeletons were obtain through differentprojections and specimen postures (every specimen with 7 projection). Fifty-seven patients with posterolateral lumbar fusion werefollowed-up from 1.5 to 4 years. Digitized radiographs of them we re photographed before fusion surgery and final follow-up.Distortion-compensated roentgen analysis (DCRA) method was used to

  13. Influence of interbody fusion intervertebral fixation on adjacent joint degeneration in patients with lumbar diseases%椎间植骨融合内固定术对腰椎疾患邻近椎间关节退变的影响

    Institute of Scientific and Technical Information of China (English)

    黄占柱; 仇小华; 张淑兰; 陈为国; 郭颖

    2014-01-01

    Objective To explore the influence of interbody fusion intervertebral fixation on adjacent joint degeneration in patients with lumbar diseases .Methods 56 patients with lumbar diseases who were taken interbody fusion intervertebral fixation were selected as the research subjects ,and the adjacent intervertebral joint degeneration in patients were followed up .Results 56 patients were followed up for 24-72 months,the average time was (41.2 ± 8.3)months.The new clinical symptoms were occurred in 12 cases(21.4%),including 8 cases of low back pain, 3 patients with leg pain,1 case of lumbocrural pain.Radiographic changes occurred in 9 cases(16.1%),9 cases of patients with new clinical symptoms ,including 5 cases of osteophyte formation or exacerbation ,2 cases for adjacent segment instability ( I degree of vertebral spondylolisthesis ) ,1 case of small joint hyperplasia stage spinal stenosis , 1 case of protrusion of intervertebral disc .In 9 patients with imaging performance ,internal fixation of upper adjacent segment degeneration in 7 cases,internal fixation of the adjacent segment degeneration in 2 cases.Conclusion Inter-body fusion intervertebral fixation in the treatment of lumbar diseases ,adjacent joint is prone to degeneration ,so the destruction of adjacent joint operation should be reduced .%目的:探讨椎间植骨融合内固定术对腰椎疾患邻近椎间关节退变的影响。方法以采用椎间植骨融合内固定术治疗的腰椎疾患患者56例作为研究对象,随访患者术后邻近椎间关节的退变情况。结果56例患者均获门诊随访,随访时间24~72个月,平均(41.2±8.3)个月。其中出现新的临床症状有12例(21.4%),其中8例为下腰痛、3例为下肢痛、1例为腰腿痛;出现影像学改变9例(16.1%),9例患者均伴有新的临床症状,其中5例为骨赘形成或加重,2例为邻近节段不稳(椎体I度滑脱),1例为小关节增生

  14. A systemic review of adjacent segment deterioration after lumbar fusion%腰椎融合术后邻近节段退化的系统回顾分析

    Institute of Scientific and Technical Information of China (English)

    沈凯; 李锋; 谭祖健

    2012-01-01

    目的 探讨腰椎融合术导致融合邻近节段退化(ASDet)发生的概率、发病机制及危险因素.方法 通过计算机检索和人工检索,对近30年来国内外发表的关于腰椎融合术导致邻近节段退化的文献进行系统回顾.结果 共搜索到301篇相关文献,筛选出30篇符合人选标准的文献.本研究发现ASDet发病率波动在6.3%~100%,邻近节段退变(ASDeg)发病率波动范围8%~100%,邻近节段疾病(ASDis)发病率波动范围6.3%~27.4%.ASDeg平均发病率高于ASDis,P=6.751×10-7(P<0.05).多种影响因素参与ASDet的发生.结论 ASDet、ASDeg 、ASDis发病率差异较大.目前ASDet发生的机制仍不明,绝大多数学者认为与手术引起的邻近节段生物力学机制改变有关.年龄大于60岁、使用内固定器械、损伤上方小关节、改变腰椎前凸和骶倾角、破坏腰椎后方组织结构、已绝经妇女是邻近节段退化性疾病发生的危险因素.然而长节段融合是否导致ASDet的发病率增高还有待进一步研究.%Objective To investigate the incidence, pathogenesis and risk factor of adjacent segment deterioration(ASDet) after lumbar fusion. Methods Our systemic review was based on the literatures of adjacent segment deterioration after lumbar fusion published around the world during the past three decades, through computer retrieval and manual retrieval. Results Out of 301 literatures, a sample of 30 literatures were chosen according to the criteria. The incidence of adjacent segment deterioration (ASDet) ranged from 6.3%~100%, and that of adjacent segment degeneration (ASDeg) ranged from 8%~100%, and that of adjacent segment disease (ASDis) ranged from 6.3%~27.4%. The average incidence of ASDeg was higher than that of ASDis, P =6.751xl0'(P <0.05). The ASDet was related with several factors. Conclusion The incidence of ASDet.ASDeg and ASDis are so different. By now, the pathogenesis of adjacent segment deterioration is

  15. Decisive factor in increase of loading at adjacent segments after lumbar fusion: operative technique, pedicle screws, or fusion itself: biomechanical analysis using finite element

    Science.gov (United States)

    Park, Joon-Hee; Kim, Ho-Joong; Kang, Kyoung-Tak; Kim, Ka-yeon; Chun, Heoung-Jae; Moon, Seong-Hwan; Lee, Hwan-Mo

    2010-03-01

    The aim of this study is to investigate the change in biomechanical milieu following removal of pedicle screws or removal of spinous process with posterior ligament complex in instrumented single level lumbar arthrodesis. We developed and validated a finite element model (FEM) of the intact lumbar spine (L2-4). Four scenarios of L3-4 lumbar fusion were simulated: posterolateral fusion (PLF) at L3-4 using pedicle screw system with preservation of PLC (Pp WiP), L3-4 lumbar posterolateral fusion state after removal of pedicle screw system with preservation of PLC (Pp WoP), L3-4 using pedicle screw system without preservation PLC (Sp WiP), L3-4 lumbar posterolateral fusion state after removal of pedicle screw system without preservation of PLC (Sp WoP). For these models, we investigated the range of motion and maximal Von mises stress of disc in all segments under various moments. All fusion models demonstrated increase in range of motion at adjacent segments compared to the intact model.For the four fusion models, the WiP model s P had the largest increase in range of motion at each adjacent segment. This study demonstrated that removal of pedicle screw system and preservation of PLC after complete lumbar spinal fusion could reduce the stress of adjacent segments synergistically and might have beneficial effects in preventing ASD.

  16. Can pathoanatomical pathways of degeneration in lumbar motion segments be identified by clustering MRI findings

    DEFF Research Database (Denmark)

    Jensen, Rikke Krüger; Jensen, Tue S; Kjaer, Per

    2013-01-01

    Magnetic Resonance Imaging (MRI) is the gold standard for detailed visualisation of spinal pathological and degenerative processes, but the prevailing view is that such imaging findings have little or no clinical relevance for low back pain. This is because these findings appear to have little...... association with treatment effects in clinical populations, and mostly a weak association with the presence of pain in the general population.However, almost all research into these associations is based on the examination of individual MRI findings, despite its being very common for multiple MRI findings...... to coexist. Therefore, this proof-of-concept study investigated the capacity of a multivariable statistical method to identify clusters of MRI findings and for those clusters to be grouped into pathways of vertebral degeneration....

  17. A study on degeneration of adjacent vertebra after pedicle screw fixation for vertebral fu-sion%椎体融合经皮椎弓根钉内固定术后邻近节段退行性变的发病机制

    Institute of Scientific and Technical Information of China (English)

    匡敬勇; 匡正达

    2015-01-01

    目的:分析椎弓根钉内固定术患者邻近节段退行性变( adjacent segment degeneration , ASD)的发生特点,探索其发病机制。方法选取2010-01至2013-12因脊柱疾病在接受手术治疗的患者72例为研究对象,均接受MRI和X线正、侧位检查,根据诊断标准计算ASD的发生率。分别采用视觉模拟评分法( VAS)和Oswestry功能障碍指数问卷表( ODI)对患者的疼痛和功能障碍情况进行评估。结果本组ASD发生率为26.39%。术前疼痛感明显,多种活动功能因疼痛而受到影响,VAS评分为5.20±1.19,ODI评分为0.43±0.12;末次随访时VAS评分为2.11±0.82,ODI评分为0.22±0.08,术前术后比较差异均有统计学意义(P<0.001)。结论椎弓根钉内固定术是引起ASD的原因之一,其机制可能与手术改变了邻近节段的受力和活动度变化有关。%Objective To study the occurrence of adjacent segment degeneration in patients who underwent pedicle screw fixa -tion, and further inquire into the pathogenesis of adjacent segment degeneration .Methods Seventy-two patients with spinal diseases underwent surgical treatment in this hospital from January 2010 to December 2013 were recruited as the study objects , all the patients underwent MRI and X ray examination , the ASD was diagnosed according to the findings of MRI and X-rays, the incidence of ASD was calculated.Visual analog scale (VAS) and Oswestry disability index questionnaire (ODI) were used to assess the pain and functional disability of patients.Results The incidence of ASD was 26.39%.The preoperative pain was significant and a variety of activity functions were affected by pain before the treatment , VAS score was 5.20 ±1.19, ODI score was 0.43 ±0.12.At the last follow-up, VAS score was 2.11 ±0.82, ODI score was 0.22 ±0.08, there was statistically significant difference between preoperative and postop-erative scores (P<0.05).Conclusions

  18. An investigation of the relationship between upper adjacent intervertebral degeneration after surgery of lumbar confluent fixation and lumbar form%腰椎椎体间融合固定术后上位相邻椎间变性和腰椎形态关系的探讨

    Institute of Scientific and Technical Information of China (English)

    周伟; 何晓斌

    2015-01-01

    Objective The cases of upper adjacent intervertebral degeneration in lumbar confluent fixation by using instrument of internal fixation and lumbar form were compared. Methods 25 cases of surgical patients with more than two years of follow-up time period from July 2010 to August 2013 were retrospectively analyzed. 14 males and 11 females, mean age was 61.2 years old, were followed up for 24 to 87 (38.8±17.1) months. Preoperative use of X-ray and CT imaging, the last pure X-ray images were evaluated during follow-up.Results Seven cases were confirmed of upper adjacent intervertebral degeneration, and the intervertebral space after a fixed elevation was significantly larger. Another facet degeneration, although the angle exhibits relatively large tendency, but had statistically significant differences.ConclusionExcessive elevation of intervertebral fixed segment is a risk factor of acceleration intervertebral adjacent segment degeneration, should be attention intraoperation.%目的:将使用内固定器械在后路腰椎固定术中出现上位临近椎间变性的病例和没出现的病例就腰椎形态进行比较。方法回顾性分析2010年7月~2013年8月手术并有2年以上随访时间的25例患者的临床资料。男14例,女11例,平均年龄61.2岁,术后随访时间24~87(38.8±17.1)个月。使用术前的X线和CT影像,最后随访时单纯的X线影像进行评价。结果7例被确认上位相邻椎间变性,术后固定的椎间隙抬高明显要大。另外退变的椎间关节角度虽然呈现比较大的倾向,但差异无统计学意义(P>0.05)。结论固定节段椎间隙的过度抬高是加速相邻节段椎间退变的危险因素,术中要有所注意。

  19. Cox regression analysis of risk factors of adjacent segment deterioration after lumbar fusion%腰椎融合术后邻近节段退化危险因素的Cox回归分析

    Institute of Scientific and Technical Information of China (English)

    陈景泉; 李念虎; 徐展望

    2015-01-01

    Objective:To investigate the risk factors and the relative degree of postoperative occurrence of adjacent segment de-terioration (ASDet) after lumbar fusion. To reduce the occurrence of ASDet,improve the clinical efficacy of surgical treatment of lumbar fusion. Methods:136 cases who had been performed lumbar fusion were selected. All cases underwent MRI for eva-luating intervertebral disc degeneration. Cox proportional hazards regression model was used to analyze the correlation and the relative risk degree from the occurrence of ASDet and 9 related factors which included age,sex,osteoporosis,intervertebral disc degeneration,laminectomy,range of lumbar fusion,intervertebral disc space distraction,internal fixation,lumbosacral fusion. Result:Multivariate Cox regression analysis showed that intervertebral disc degeneration (RR=4.272,P=0.000) and intervertebral disc space distraction (RR=2.022,P=0.024) were significant correlated with the occurrence of ASDet. Conclusion:To choose operation reas-onably for the patients with intervertebral disc degeneration and not to distract the intervertebral disc space overmuch could re-duce the occurrence of ASDet.%目的:探讨腰椎融合术后邻近节段退化(adjacent segment deterioration,ASDet)的危险因素及相对风险度,以求降低患者术后发生ASDet的风险。方法:选择山东中医药大学附属医院2010年9月至2014年7月行腰椎融合手术患者136例。应用MRI评估患者术前椎间盘退变情况,应用Cox比例风险回归模型分析腰椎融合术后ASDet的发生与年龄、性别、骨质疏松、术前邻近节段椎间盘退变、椎板减压术、融合节段数、椎间隙撑开、使用内固定、腰骶椎融合等9个因素的相关性和风险性。结果:术前椎间盘退变(RR=4.272,P<0.01)和椎间隙撑开(RR=2.022,P=0.024)与术后ASDet的发生呈显著相关。结论:术前椎间盘退变及术中行椎间隙撑开可增加术后发生ASDet的风险。

  20. Changes in the Expressions of Iba1 and Calcitonin Gene-Related Peptide in Adjacent Lumbar Spinal Segments after Lumbar Disc Herniation in a Rat Model.

    Science.gov (United States)

    Cho, Hee Kyung; Ahn, Sang Ho; Kim, So-Yeon; Choi, Mi-Jung; Hwang, Se Jin; Cho, Yun Woo

    2015-12-01

    Lumbar disc herniation is commonly encountered in clinical practice and can induce sciatica due to mechanical and/or chemical irritation and the release of proinflammatory cytokines. However, symptoms are not confined to the affected spinal cord segment. The purpose of this study was to determine whether multisegmental molecular changes exist between adjacent lumbar spinal segments using a rat model of lumbar disc herniation. Twenty-nine male Sprague-Dawley rats were randomly assigned to either a sham-operated group (n=10) or a nucleus pulposus (NP)-exposed group (n=19). Rats in the NP-exposed group were further subdivided into a significant pain subgroup (n=12) and a no significant pain subgroup (n=7) using mechanical pain thresholds determined von Frey filaments. Immunohistochemical stainings of microglia (ionized calcium-binding adapter molecule 1; Iba1), astrocytes (glial fibrillary acidic protein; GFAP), calcitonin gene-related peptide (CGRP), and transient receptor potential vanilloid 1 (TRPV1) was performed in spinal dorsal horns and dorsal root ganglions (DRGs) at 10 days after surgery. It was found immunoreactivity for Iba1-positive microglia was higher in the L5 (P=0.004) dorsal horn and in the ipsilateral L4 (P=0.009), L6 (P=0.002), and S1 (P=0.002) dorsal horns in the NP-exposed group than in the sham-operated group. The expression of CGRP was also significantly higher in ipsilateral L3, L4, L6, and S1 segments and in L5 DRGs at 10 days after surgery in the NP-exposed group than in the sham-operated group (Plumbar disc herniation upregulates microglial activity and CGRP expression in many adjacent and ipsilateral lumbar spinal segments.

  1. A study of retrograde degeneration of median nerve forearm segment in carpal tunnel syndrome of variable severities

    Directory of Open Access Journals (Sweden)

    Mona Mokhtar El Bardawil

    2014-12-01

    Conclusions: Retrograde degeneration exists in patients with CTS. Forearm median motor NCV and median mixed conduction study are valid electrophysiologic tools for the assessment of RGD in patients with CTS. Retrograde degeneration is not related to grade of severity of CTS.

  2. The effects of cervical intervertebral disc replacemen on the range of movement and pressure change of intervertebral discs at adjacent segments%人工椎间盘置换对颈椎临近节段活动度及椎间盘内压力的影响

    Institute of Scientific and Technical Information of China (English)

    张维成; 麦伟; 廖兴华; 黄晓魏; 方文焕; 李智

    2009-01-01

    Objective To study the efects of cervical intervertebral disc replacemen on the range of movement and pressure change of intervertebral discs at adjacent segments.Methods 20 patients with cervical spondylosis were treated with cervical intervertebral disc replacement.The pressure change of intervertebral discs at adjacent segments were measured in the operation,and dynamical X-rays examination were carried out preoperatively and 3 month and 6 month postoperatively.The range of movement at the adjacent segments were studied.Results There were no significant diferences between pre-operative and post-operative on the range of movement and pressure change of intervertebral discs at adjacent segments(P>0.05).Conclusion The normal range of movement and pressure of intervertebral discs at the adjacent segments can be saved in the application of cervical intervertebral disc replacement,and then adjacent degeneration can be prevented.%目的 观察人工椎间盘置换对颈椎临近节段活动度及椎间盘内压力的影响.方法 应用人工椎间盘置换术治疗颈椎病患者20例,于术中椎间盘置换前后分别测量临近节段椎间盘内压力,并于术前及术后3个月、半年分别摄颈椎动力位x线片,观察上下临近节段的活动度.结果 人工椎间盘置换术后颈椎临近节段椎间盘内压力较术前无明显变化(P>0.05),上下临近关节活动度未显著增加(P>0.05).结论 人工椎间盘置换在治疗颈椎病的同时保留正常的椎间运动而不影响邻近节段,从而防止邻近节段继发性退变.

  3. Effects of posterior lumbar spinal fusion on the stability of unstable lumbar segment and biomechanical properties of adjacent segments: a finite element study%腰椎后路融合手术对失稳模型节段稳定性及相邻节段力学的影响

    Institute of Scientific and Technical Information of China (English)

    费琦; 赵凡; 杨雍; 李东; 李锦军; 王奇; 林吉生; 严华刚; 王炳强

    2015-01-01

    目的 在腰椎单节段退变手术失稳模型基础上比较两种融合术式对腰椎失稳节段稳定性及相邻节段的力学影响.方法 用有限元方法建立切除腰椎单节段退变L4-5椎间小关节内侧2/3及相应椎板的L3-S1术后失稳模型,在此基础上模拟腰椎后外侧融合术(PLF)和后路腰椎椎间融合术(PLIF),记录手术前后失稳节段(L4-5)在生理载荷下的运动范围(ROM)变化,并记录生理载荷下相邻节段(L3-4、L5-S1)的ROM变化以及垂直载荷下相邻节段椎间盘Von Mises应力变化.结果 两种术式术后失稳节段(L4-5)的稳定性均得到明显恢复.与失稳模型L4-5节段ROM相比,PLF模型前屈、后伸、侧向旋转ROM分别减少了87%、87%和88%;PLIF模型前屈、后伸、侧向旋转ROM分别减少了85%、84%和86%.与失稳模型相比,两种术式均未导致相邻节段(L3-4、L5-S1)的(ROM)增大;相邻节段椎间盘Von Mises应力集中部位由纤维环后部转向前外侧,同时应力较术前失稳模型明显增大,两种术式对相邻节段椎间盘力学影响的差异无统计学意义[(1.056±0.061)mPa比(1.070±0.075)mPa;(1.147±0.055)mPa比(1.162±0.075)mPa,P>0.05].结论 PLF和PLIF均可恢复腰椎椎板减压术后失稳节段的稳定性,两种术式均可增加相邻椎间盘的应力,可能和术后相邻节段椎间盘退变相关.%Objective To explore the effects of posterolateral lumbar fusion (PLF) and posterior lumbar interbody fusion (PLIF) on the stability of postoperative unstable single lumbar segment and the biomechanical alterations of the adjacent segments.Methods A finite element model of L3-S1 segments with a single segmental degeneration at the L4-5 level was established, and the model of L4-5 segmental instability after posterior laminectomy and facetectomy was also established, in which laminar and interior 2/3 area of bilateral facet joints were resected.Physical loads were applied to the models and the changes

  4. Cervical anterior hybrid technique with bi-level Bryan artificial disc replacement and adjacent segment fusion for cervical myelopathy over three consecutive segments.

    Science.gov (United States)

    Chen, Jiang; Xu, Lin; Jia, Yu-Song; Sun, Qi; Li, Jin-Yu; Zheng, Chen-Ying; Bai, Chun-Xiao; Yu, Qin-Sheng

    2016-05-01

    This study aimed to assess the preliminary clinical efficacy and feasibility of the hybrid technique for multilevel cervical myelopathy. Considering the many shortcomings of traditional treatment methods for multilevel cervical degenerative myelopathy, hybrid surgery (bi-level Bryan artificial disc [Medtronic Sofamor Danek, Memphis, TN, USA] replacement and anterior cervical discectomy and fusion) should be considered. Between March 2006 and November 2012, 108 patients (68 men and 40 women, average age 45years) underwent hybrid surgery. Based on the Japanese Orthopaedic Association (JOA) score, Neck Disability Index (NDI), and Odom's criteria, the clinical symptoms and neurological function before and after surgery were evaluated. Mean surgery duration was 90minutes, with average blood loss of 30mL. Mean follow-up duration was 36months. At the final follow-up, the mean JOA (± standard deviation) scores were significantly higher compared with preoperative values (15.08±1.47 versus 9.18±1.22; P<0.01); meanwhile, NDI values were markedly decreased (12.32±1.03 versus 42.68±1.83; P<0.01). Using Odom's criteria, the clinical outcomes were rated as excellent (76 patients), good (22 patients), fair (six patients), and poor (four patients). These findings indicate that the hybrid method provides an effective treatment for cervical myelopathy over three consecutive segments, ensuring a good clinical outcome. Copyright © 2015 Elsevier Ltd. All rights reserved.

  5. Dynesys dynamic neutralization system for the treatment of lumbar degenerative disease and the effect on the adjacent segment%Dynesys系统治疗腰椎退行性疾病对邻近节段的影响**☆

    Institute of Scientific and Technical Information of China (English)

    杨波; 万盛钰; 曾勉东; 吕玉明; 方世兵; 谢景开

    2013-01-01

    polyethylene terephthalate rope. Clinical outcomes were evaluated using visual analogue scale and Oswestry disability index before and after operation. The degeneration of the adjacent segment was evaluated according to Woodend score;the treatment efficiency was assessed with Macnab criteria. RESULTS AND CONCLUSION:Al the 20 patients were fol owed-up for 22-31 months. According to Macnab criteria, excel ent in 11 cases, good in six cases, fair in three cases, and the excel ent and good rate was 83%. The visual analogue scale score was decreased from preoperative (8.29±1.50) to postoperative (2.25±1.67) (P0.05). This study shows Dynesys system is safe and effective in the treatment of lumbar degenerative diseases and multi-center randomized control ed clinical trials are needed to identify whether it can reduce or prevent the occurrence of disc degeneration of adjacent segments.

  6. [TREATMENT OF POST-SPONDYLODESIS, ADJACENT-SEGMENT DISEASE WITH MINIMALLY INVASIVE, ANTEROLATERAL SURGERY ON THE LUMBAR SPINE: IS THERE IS NO NEED FOR DORSAL OPERATION?].

    Science.gov (United States)

    Schwarcz, Attila; Szakály, Péter; Büki, András; Dóczi, Tamás

    2015-07-30

    Adjacent segment disease (ASD) occurs with a probability of 30% in the lumbar spine following spinal fusion surgery. Usually advanced degenerative changes happen cranially to the fused lumbar segment. Thus, secondary spinal instability, stenosis, spodylolisthesis, foraminal stenosis can lead to the recurrence of the pain not always amenable to conservative measures. A typical surgical solution to treat ASD consists of posterior revision surgery including decompression, change or extension of the instrumentation and fusion to the rostral level. It results in a larger operation with considerable risk of complications. We present a typical case of ASD treated surgically with a new minimally invasive method not yet performed in Hungary. We use anterolateral abdominal muscle splitting approach to reach the lumbar spine through the retroperitoneum. A discectomy is performed by retracting the psoas muscle dorsally. The intervertebral bony fusion is achieved by implanting a cage with large volume that is stuffed with autologous bone or tricalcium phosphate. A cage with large volume results in excellent annulus fibrosus tension, immediate stability and provides large surface for bony fusion. A stand-alone cage construct can be supplemented with lateral screw/rod/plate fixation. The advantage of the new technique for the treatment of ASD includes minimal blood loss, short operation time, significantly less postoperative pain and much lower complication rate.

  7. 腰椎问盘置换术后对邻近节段腰椎终板的应力影响与影响因素分析%Stress effects and influencing factors of lumbar disc replacement surgery for adjacent segment vertebral endplate

    Institute of Scientific and Technical Information of China (English)

    孙云明; 戚广秀; 王立民

    2012-01-01

    Objective To investigate the stress effects and influencing factors of lumbar disc replacement surgery for adjacent segment vertebral endplate. Methods Four fresh adult lumbar spine (Li-Si) segments of specimens were selected, SMH-1 artificial disc experimental prosthesis for artificial disc replacement operation was used. All adjacent segment end-surgery, and then proceed to axial compression movement test. Results Adjacent segment endplate average maximum stress showed increased in axial compression, compared with normal lumbar interverlebral disc status group, it had significant difference (P < 0.05), but significantly less than lumbar diseeciomy (P < 0.05). Adjacent segment stress test fixed---point, end plate type and operation on the lumbar spine endplate of the adjacent segments had significant biological effects. Conclusion The stress load of lumbar interverlebral disc replacement on the adjacent segment endplate is significantly less than the lumbar discectomy, it can be effective in preventing the top of the adjacent segments and accelerate degeneration, should be widely applied.%目的 探讨腰椎问盘置换术后对邻近节段腰椎终板的生物影响.方法 选用4具新鲜成人腰椎(L2~S1)节段标本,采用SMH-1型人工腰椎间盘实验假体进行人工腰椎间盘置换操作.所有邻近节段终板模型标本选择正常腰椎间盘、髓核摘除术和人工腰椎间盘置换术,然后进行轴向压缩运动测验.结果 轴向压缩下邻近节段终板平均最大应力均显示有所增大,与腰椎间盘正常状态组别比较差异有统计学意义(P<0.05),但是明显少于腰椎间盘摘除术(P<0.05).邻近节段应力测试定点,终板类型以及手术方法对邻近节段腰椎终板都有明显的生物影响.结论 腰椎问盘置换术对上邻近节段终板应力负荷明显小于腰椎间盘摘除术,可有效地预防上方邻近节段加速退变,值得推广应用.

  8. Posteriorly Directed Shear Loads and Disc Degeneration Affect the Torsional Stiffness of Spinal Motion Segments A Biomechanical Modeling Study

    NARCIS (Netherlands)

    Homminga, Jasper; Lehr, Anne M.; Meijer, Gerdine J. M.; Janssen, Michiel M. A.; Schlosser, Tom P. C.; Verkerke, Gijsbertus J.; Castelein, Rene M.

    2013-01-01

    Study Design. Finite element study. Objective. To analyze the effects of posterior shear loads, disc degeneration, and the combination of both on spinal torsion stiffness. Summary of Background Data. Scoliosis is a 3-dimensional deformity of the spine that presents itself mainly in adolescent girls

  9. Posteriorly directed shear loads and disc degeneration affect the torsional stiffness of spinal motion segments; a biomechanical modeling study

    NARCIS (Netherlands)

    Homminga, J.J.; Lehr, A.M.; Meijer, G.J.M.; Janssen, M.M.A.; Schlösser, T.P.C.; Verkerke, G.J.; Castelein, R.M.

    2013-01-01

    Objective. To analyze the effects of posterior shear loads, disc degeneration, and the combination of both on spinal torsion stiffness. Summary of Background Data. Scoliosis is a 3-dimensional deformity of the spine that presents itself mainly in adolescent girls and elderly patients. Our concept o

  10. Semiautomated segmentation and analysis of retinal layers in three-dimensional spectral-domain optical coherence tomography images of patients with atrophic age-related macular degeneration.

    Science.gov (United States)

    Hu, Zhihong; Shi, Yue; Nandanan, Kiran; Sadda, Srinivas R

    2017-01-01

    Historically, regular drusen and geographic atrophy (GA) have been recognized as the hallmarks of nonneovascular age-related macular degeneration (AMD). Recent imaging developments have revealed another distinct nonneovascular AMD phenotype, reticular pseudodrusen (RPD). We develop an approach to semiautomatically quantify retinal surfaces associated with various AMD lesions (i.e., regular drusen, RPD, and GA) in spectral domain (SD) optical coherence tomography (OCT) images. More specifically, a graph-based algorithm was used to segment multiple retinal layers in SD-OCT volumes. Varying surface feasibility constraints based on the presegmentation were applied on the double-surface graph search to refine the surface segmentation. The thicknesses of these layers and their correlation with retinal functional measurements, including microperimetry (MP) sensitivity and visual acuity (VA), were investigated. The photoreceptor outer segment layer demonstrated significant thinning with a reduction in MP sensitivity and VA score when atrophic AMD lesions were present. Regular drusen and RPD were separately segmented on SD-OCT images to allow their characteristics and distribution to be studied separately. The mean thickness of regular drusen was found to significantly correlate with the VA score. RPD appeared to be distributed evenly throughout the macula and regular drusen appeared to be more concentrated centrally.

  11. A hybrid segmentation approach for geographic atrophy in fundus auto-fluorescence images for diagnosis of age-related macular degeneration.

    Science.gov (United States)

    Lee, Noah; Laine, Andrew F; Smith, R Theodore

    2007-01-01

    Fundus auto-fluorescence (FAF) images with hypo-fluorescence indicate geographic atrophy (GA) of the retinal pigment epithelium (RPE) in age-related macular degeneration (AMD). Manual quantification of GA is time consuming and prone to inter- and intra-observer variability. Automatic quantification is important for determining disease progression and facilitating clinical diagnosis of AMD. In this paper we describe a hybrid segmentation method for GA quantification by identifying hypo-fluorescent GA regions from other interfering retinal vessel structures. First, we employ background illumination correction exploiting a non-linear adaptive smoothing operator. Then, we use the level set framework to perform segmentation of hypo-fluorescent areas. Finally, we present an energy function combining morphological scale-space analysis with a geometric model-based approach to perform segmentation refinement of false positive hypo- fluorescent areas due to interfering retinal structures. The clinically apparent areas of hypo-fluorescence were drawn by an expert grader and compared on a pixel by pixel basis to our segmentation results. The mean sensitivity and specificity of the ROC analysis were 0.89 and 0.98%.

  12. A level-set method for pathology segmentation in fluorescein angiograms and en face retinal images of patients with age-related macular degeneration

    Science.gov (United States)

    Mohammad, Fatimah; Ansari, Rashid; Shahidi, Mahnaz

    2013-03-01

    The visibility and continuity of the inner segment outer segment (ISOS) junction layer of the photoreceptors on spectral domain optical coherence tomography images is known to be related to visual acuity in patients with age-related macular degeneration (AMD). Automatic detection and segmentation of lesions and pathologies in retinal images is crucial for the screening, diagnosis, and follow-up of patients with retinal diseases. One of the challenges of using the classical level-set algorithms for segmentation involves the placement of the initial contour. Manually defining the contour or randomly placing it in the image may lead to segmentation of erroneous structures. It is important to be able to automatically define the contour by using information provided by image features. We explored a level-set method which is based on the classical Chan-Vese model and which utilizes image feature information for automatic contour placement for the segmentation of pathologies in fluorescein angiograms and en face retinal images of the ISOS layer. This was accomplished by exploiting a priori knowledge of the shape and intensity distribution allowing the use of projection profiles to detect the presence of pathologies that are characterized by intensity differences with surrounding areas in retinal images. We first tested our method by applying it to fluorescein angiograms. We then applied our method to en face retinal images of patients with AMD. The experimental results included demonstrate that the proposed method provided a quick and improved outcome as compared to the classical Chan-Vese method in which the initial contour is randomly placed, thus indicating the potential to provide a more accurate and detailed view of changes in pathologies due to disease progression and treatment.

  13. Rapid mapping of functional cis-acting RNA elements by recovery of virus from a degenerate RNA population: application to genome segment 10 of bluetongue virus.

    Science.gov (United States)

    Boyce, M; McCrae, M A

    2015-10-01

    The regulatory elements which control the processes of virus replication and gene expression in the Orbivirus genus are uncharacterized in terms of both their locations within genome segments and their specific functions. The reverse genetics system for the type species, Bluetongue virus, has been used in combination with RNA secondary structure prediction to identify and map the positions of cis-acting regions within genome segment 10. Through the simultaneous introduction of variability at multiple nucleotide positions in the rescue RNA population, the functional contribution of these positions was used to map regions containing cis-acting elements essential for virus viability. Nucleotides that were individually lethal when varied mapped within a region of predicted secondary structure involving base pairing between the 5' and 3' ends of the transcript. An extended region of predicted perfect base pairing located within the 3' untranslated region of the genome segment was also found to be required for virus viability. In contrast to the identification of individually lethal mutations, gross alteration of the composition of this predicted stem region was possible, providing the base-pairing potential between the two strands was maintained, identifying a structural feature predicted to be conserved throughout the Orbivirus genus. The approach of identifying cis-acting sequences through sequencing the recovered virus following the rescue of a degenerate RNA population is broadly applicable to viruses where reverse genetics is available.

  14. Segmentation error and macular thickness measurements obtained with spectral-domain optical coherence tomography devices in neovascular age-related macular degeneration

    Directory of Open Access Journals (Sweden)

    Moosang Kim

    2013-01-01

    Full Text Available Purpose: To evaluate frequency and severity of segmentation errors of two spectral-domain optical coherence tomography (SD-OCT devices and error effect on central macular thickness (CMT measurements. Materials and Methods: Twenty-seven eyes of 25 patients with neovascular age-related macular degeneration, examined using the Cirrus HD-OCT and Spectralis HRA + OCT, were retrospectively reviewed. Macular cube 512 × 128 and 5-line raster scans were performed with the Cirrus and 512 × 25 volume scans with the Spectralis. Frequency and severity of segmentation errors were compared between scans. Results: Segmentation error frequency was 47.4% (baseline, 40.7% (1 month, 40.7% (2 months, and 48.1% (6 months for the Cirrus, and 59.3%, 62.2%, 57.8%, and 63.7%, respectively, for the Spectralis, differing significantly between devices at all examinations (P < 0.05, except at baseline. Average error score was 1.21 ± 1.65 (baseline, 0.79 ± 1.18 (1 month, 0.74 ± 1.12 (2 months, and 0.96 ± 1.11 (6 months for the Cirrus, and 1.73 ± 1.50, 1.54 ± 1.35, 1.38 ± 1.40, and 1.49 ± 1.30, respectively, for the Spectralis, differing significantly at 1 month and 2 months (P < 0.02. Automated and manual CMT measurements by the Spectralis were larger than those by the Cirrus. Conclusions: The Cirrus HD-OCT had a lower frequency and severity of segmentation error than the Spectralis HRA + OCT. SD-OCT error should be considered when evaluating retinal thickness.

  15. Preservation of the Photoreceptor Inner/Outer Segment Junction in Dry Age-Related Macular Degeneration Treated by Rheohemapheresis

    Directory of Open Access Journals (Sweden)

    Eva Rencová

    2015-01-01

    Full Text Available Aim. To evaluate the long-term effect of rheohemapheresis (RHF treatment of age-related macular degeneration (AMD on photoreceptor IS/OS junction status. Methods. In our study, we followed 24 patients with dry AMD and drusenoid retinal pigment epithelium detachment (DPED for a period of more than 2.5 years. Twelve patients (22 eyes were treated by RHF and 12 controls (18 eyes were randomized. The treated group underwent 8 RHF standardized procedures. We evaluated best-corrected visual acuity, IS/OS junction status (SD OCT, and macular function (multifocal electroretinography at baseline and at 2.5-year follow-up. Results. RHF caused a decrease of whole-blood viscosity/plasma viscosity at about 15/12%. BCVA of treated patients increased insignificantly P=0.187 from median 74.0 letters (56.2 to 81.3 letters to median 79.0 letters (57.3 to 83.4 letters, but it decreased significantly from 74.0 letters (25.2 to 82.6 letters to 72.5 letters (23.4 to 83.1 letters in the control group P=0.041. The mfERG responses in the region of eccentricity between 1.8° and 7° were significantly higher in treated patients P=0.04. Conclusions. RHF contributed to sparing of photoreceptor IS/OS junction integrity in the fovea, which is assumed to be a predictive factor for preservation of visual acuity.

  16. Comprehensive comparing percutaneous endoscopic lumbar discectomy with posterior lumbar internal fixation for treatment of adjacent segment lumbar disc prolapse with stable retrolisthesis: A retrospective case-control study.

    Science.gov (United States)

    Sun, Yapeng; Zhang, Wei; Qie, Suhui; Zhang, Nan; Ding, Wenyuan; Shen, Yong

    2017-07-01

    The study was to comprehensively compare the postoperative outcome and imaging parameter characters in a short/middle period between the percutaneous endoscopic lumbar discectomy (PELD) and the internal fixation of bone graft fusion (the most common form is posterior lumbar interbody fusion [PLIF]) for the treatment of adjacent segment lumbar disc prolapse with stable retrolisthesis after a previous lumbar internal fixation surgery.In this retrospective case-control study, we collected the medical records from 11 patients who received PELD operation (defined as PELD group) for and from 13 patients who received the internal fixation of bone graft fusion of lumbar posterior vertebral lamina decompression (defined as control group) for the treatment of the lumbar disc prolapse combined with stable retrolisthesis at Department of Spine Surgery, the Third Hospital of Hebei Medical University (Shijiazhuang, China) from May 2010 to December 2015. The operation time, the bleeding volume of perioperation, and the rehabilitation days of postoperation were compared between 2 groups. Before and after surgery at different time points, ODI, VAS index, and imaging parameters (including Taillard index, inter-vertebral height, sagittal dislocation, and forward bending angle of lumbar vertebrae) were compared.The average operation time, the blooding volume, and the rehabilitation days of postoperation were significantly less in PELD than in control group. The ODI and VAS index in PELD group showed a significantly immediate improving on the same day after the surgery. However, Taillard index, intervertebral height, sagittal dislocation in control group showed an immediate improving after surgery, but no changes in PELD group till 12-month after surgery. The forward bending angle of lumbar vertebrae was significantly increased and decreased in PELD and in control group, respectively.PELD operation was superior in terms of operation time, bleeding volume, recovery period, and financial

  17. The Finite Element Analysis of Postoperative Adjacent Segmental Lumbar Fusion Intervertebral Disc Stress%腰椎融合术后临近节段椎间盘应力的有限元分析

    Institute of Scientific and Technical Information of China (English)

    潘志强; 叶立民; 王求永; 黄剑波; 傅冬梅

    2014-01-01

    Objective:To analysis model under different loads and stress changes by posterior lumbar discectomy through the establishment of normal, L4-5 and L4-S1 fusion and internal fixation model.Method: Analyzed 98 image nodes from 1 volunteers what were divided unit to establish the normal lumbar motion segment (L1-S1) finite element model and L4-5, L4-S1 segment of posterior lumbar interbody fusion and internal fixation model, the three models with five direction load, calculation of adjacent segment disc shall be stress variation, and the results were statistically analyzed.Result: The research showed that the upper two segments adjacent segment than the single disc fusion segment average effective stress in flexion, extension , lateral flexion , rotation load difference was statistically significant(P0.05), whether it was single or double segment L4-5 segment L4-S1 was fixed , the neighboring L3~4 disc effective stress in flexion, extension , vertical compression , lateral flexion, rotation were greater than unfused fixed, the difference was statistically significant(P0.05)。不管是单节段L4~5还是双节段L4~S1固定后,邻近L3~4椎间盘有效应力在前屈、后伸、垂直压缩、侧屈、旋转时均大于未融合固定,差异有统计学意义(P<0.05),各加载方式两两比较,加载平均应力由大到小依次为旋转、侧屈、后伸、前屈和垂直压缩,且两两之间比较差异有统计学意义(P<0.05)。结论:腰椎后路椎间融合术后,节段融合固定的应力要明显大于非融合固定临近椎间盘的应力,而且更容易加快邻近椎间盘的退变,双节段腰椎融合内固定比单节段在大部分活动状态下更易加快邻近椎间盘退变,尤其是旋转活动。

  18. Disc degeneration: current surgical options

    Directory of Open Access Journals (Sweden)

    C Schizas

    2010-10-01

    Full Text Available Chronic low back pain attributed to lumbar disc degeneration poses a serious challenge to physicians. Surgery may be indicated in selected cases following failure of appropriate conservative treatment. For decades, the only surgical option has been spinal fusion, but its results have been inconsistent. Some prospective trials show superiority over usual conservative measures while others fail to demonstrate its advantages. In an effort to improve results of fusion and to decrease the incidence of adjacent segment degeneration, total disc replacement techniques have been introduced and studied extensively. Short-term results have shown superiority over some fusion techniques. Mid-term results however tend to show that this approach yields results equivalent to those of spinal fusion. Nucleus replacement has gained some popularity initially, but evidence on its efficacy is scarce. Dynamic stabilisation, a technique involving less rigid implants than in spinal fusion and performed without the need for bone grafting, represents another surgical option. Evidence again is lacking on its superiority over other surgical strategies and conservative measures. Insertion of interspinous devices posteriorly, aiming at redistributing loads and relieving pain, has been used as an adjunct to disc removal surgery for disc herniation. To date however, there is no clear evidence on their efficacy. Minimally invasive intradiscal thermocoagulation techniques have also been tried, but evidence of their effectiveness is questioned. Surgery using novel biological solutions may be the future of discogenic pain treatment. Collaboration between clinicians and basic scientists in this multidisciplinary field will undoubtedly shape the future of treating symptomatic disc degeneration.

  19. 人工颈椎间盘置换与前路颈椎间盘切除融合后邻近节段椎间盘应力分布的有限元对比%Comparison of stress distribution of adjacent segments after artificial cervical disc replacement versus anterior cervical discectomy and fusion:a finite element analysis

    Institute of Scientific and Technical Information of China (English)

    刘雅普; 侯秀伟; 吴广良; 夏虹

    2016-01-01

    背景:通过前期的临床随访研究发现,前路颈椎融合后邻近节段椎间盘退变速度要快于人工颈椎间盘置换,人工颈椎间盘置换相较于前路颈椎融合可以保持良好的置换节段活动度,是否置换后邻近椎间盘的应力情况与融合之间存在着差异需要进一步研究。目的:对比人工颈椎间盘置换与前路颈椎间盘切除融合后邻近节段椎间盘的应力分布情况。方法:选择1名30岁健康男性志愿者,人工颈椎间盘和颈椎前路钢板实物进行薄层CT扫描,通过Mimics 10.01及Geomagic Studio.v11软件重建出三维图像,将以上三维数据导入Abaqus 6.9有限元分析软件中进行网格划分、赋值、应力分析。利用有限元方法分析模拟人工颈椎间盘置换及前路颈椎间盘切除融合后邻近节段椎间盘的应力变化。结果与结论:①在相同的预载荷条件下,前屈、后伸、侧屈等运动状态时前路颈椎间盘切除融合后邻近节段椎间盘的应力明显大于正常人相应节段椎间盘应力;而人工椎间盘植入后与正常人相比,在前屈、后伸、侧屈等运动状态时邻近节段椎间盘的应力差异无显著性意义;②前路颈椎间盘切除融合组与人工颈椎间盘置换组相比较,融合组术后邻近节段椎间盘的应力较置换组增大10.3%-51.6%;③有限元分析方法发现,前路颈椎间盘切除融合后邻近节段椎间盘应力大于人工颈椎间盘置换组,随着随访时间的延长,相较于传统前路减压融合,人工颈椎间盘置换可能将更好地发挥其对邻近节段椎间盘的保护作用。%BACKGROUND:Previous clinical fol ow-up study showed that disc degeneration of adjacent segment after anterior cervical discectomy and fusion was faster than that of artificial cervical disc replacement. Compared with the anterior cervical discectomy and fusion, artificial cervical disc replacement can maintain a

  20. 腰椎滑脱椎弓根螺钉内固定融合术后邻近节段椎间隙变化的相关研究%Related study on adjacent segments intervertebral space change after spondylolishesis pedicle screw internal fixation and fusion operation

    Institute of Scientific and Technical Information of China (English)

    贾鹏; 赵文国; 王勇贵

    2013-01-01

    retrospectively.The change of adjacent segments intervertebral space in fixed fusion zone after operation was observed;whether "Suspensory fixation" or not having influence on the change of height of adjacent intervertebral space and different adjacent segment on the change of height of adjacent intervertebral space were compared.The relation between the change of the height of the adjacent intervertebral space and the angle of pedicle screw was analyzed.Results In the operating-group,the heights of L4/L5 in the upper of the L5-S1 fixed group after postoperative one year reduced slightly than those after postoperative moment,but the change had no statistical significance (P > 0.05) ; the heights of L3/L4 in the upper of the L4-L5 fixed group after postoperative one year reduced slightly than those after postoperative moment,but the change also had no statistical significance(P > 0.05) ;the changes between the L5-S1 fixed group and the L4-L5 fixed group had no obvious difference(P >0.05).In the L4-L5 fixed group,there had no obvious difference between the change of the height of the upper adjacent intervertebral space and the change of the height of the lower one in fixed fusion zone(P > 0.05).When the operating-group was divided into two groups according to the angle of pedicle screw(< 6° or ≥6°) and compared them,the change of the height of the upper adjacent intervertebral space in fixed fusion zone had no obvious difference(P > 0.05).But there was positive and correlative relation between changes of the height of the adjacent intervertebral space and the angle of pedicle screw in fixed fusion zone (r =0.373,P =0.039).Conclusion " Suspensory fixation" or not is no influence on the change of height of adjacent intervertebral space in fixed fusion zone.There is no difference on the risk of degeneration between upper and lower segment adjacent to the fusional area.There has positive and correlative relation between the change of height of the upper intervertebral

  1. Adjacent-level arthroplasty following cervical fusion.

    Science.gov (United States)

    Rajakumar, Deshpande V; Hari, Akshay; Krishna, Murali; Konar, Subhas; Sharma, Ankit

    2017-02-01

    OBJECTIVE Adjacent-level disc degeneration following cervical fusion has been well reported. This condition poses a major treatment dilemma when it becomes symptomatic. The potential application of cervical arthroplasty to preserve motion in the affected segment is not well documented, with few studies in the literature. The authors present their initial experience of analyzing clinical and radiological results in such patients who were treated with arthroplasty for new or persistent arm and/or neck symptoms related to neural compression due to adjacent-segment disease after anterior cervical discectomy and fusion (ACDF). METHODS During a 5-year period, 11 patients who had undergone ACDF anterior cervical discectomy and fusion (ACDF) and subsequently developed recurrent neck or arm pain related to adjacent-level cervical disc disease were treated with cervical arthroplasty at the authors' institution. A total of 15 devices were implanted (range of treated levels per patient: 1-3). Clinical evaluation was performed both before and after surgery, using a visual analog scale (VAS) for pain and the Neck Disability Index (NDI). Radiological outcomes were analyzed using pre- and postoperative flexion/extension lateral radiographs measuring Cobb angle (overall C2-7 sagittal alignment), functional spinal unit (FSU) angle, and range of motion (ROM). RESULTS There were no major perioperative complications or device-related failures. Statistically significant results, obtained in all cases, were reflected by an improvement in VAS scores for neck/arm pain and NDI scores for neck pain. Radiologically, statistically significant increases in the overall lordosis (as measured by Cobb angle) and ROM at the treated disc level were observed. Three patients were lost to follow-up within the first year after arthroplasty. In the remaining 8 cases, the duration of follow-up ranged from 1 to 3 years. None of these 8 patients required surgery for the same vertebral level during the follow

  2. Tyro3 Modulates Mertk-Associated Retinal Degeneration.

    Science.gov (United States)

    Vollrath, Douglas; Yasumura, Douglas; Benchorin, Gillie; Matthes, Michael T; Feng, Wei; Nguyen, Natalie M; Sedano, Cecilia D; Calton, Melissa A; LaVail, Matthew M

    2015-12-01

    Inherited photoreceptor degenerations (IPDs) are the most genetically heterogeneous of Mendelian diseases. Many IPDs exhibit substantial phenotypic variability, but the basis is usually unknown. Mutations in MERTK cause recessive IPD phenotypes associated with the RP38 locus. We have identified a murine genetic modifier of Mertk-associated photoreceptor degeneration, the C57BL/6 (B6) allele of which acts as a suppressor. Photoreceptors degenerate rapidly in Mertk-deficient animals homozygous for the 129P2/Ola (129) modifier allele, whereas animals heterozygous for B6 and 129 modifier alleles exhibit an unusual intermixing of degenerating and preserved retinal regions, with females more severely affected than males. Mertk-deficient mice homozygous for the B6 modifier allele display degeneration only in the far periphery, even at 8 months of age, and have improved retinal function compared to animals homozygous for the 129 allele. We genetically mapped the modifier to an approximately 2-megabase critical interval that includes Tyro3, a paralog of Mertk. Tyro3 expression in the outer retina varies with modifier genotype in a manner characteristic of a cis-acting expression quantitative trait locus (eQTL), with the B6 allele conferring an approximately three-fold higher expression level. Loss of Tyro3 function accelerates the pace of photoreceptor degeneration in Mertk knockout mice, and TYRO3 protein is more abundant in the retinal pigment epithelium (RPE) adjacent to preserved central retinal regions of Mertk knockout mice homozygous for the B6 modifier allele. Endogenous human TYRO3 protein co-localizes with nascent photoreceptor outer segment (POS) phagosomes in a primary RPE cell culture assay, and expression of murine Tyro3 in cultured cells stimulates phagocytic ingestion of POS. Our findings demonstrate that Tyro3 gene dosage modulates Mertk-associated retinal degeneration, provide strong evidence for a direct role for TYRO3 in RPE phagocytosis, and suggest

  3. Tyro3 Modulates Mertk-Associated Retinal Degeneration.

    Directory of Open Access Journals (Sweden)

    Douglas Vollrath

    2015-12-01

    Full Text Available Inherited photoreceptor degenerations (IPDs are the most genetically heterogeneous of Mendelian diseases. Many IPDs exhibit substantial phenotypic variability, but the basis is usually unknown. Mutations in MERTK cause recessive IPD phenotypes associated with the RP38 locus. We have identified a murine genetic modifier of Mertk-associated photoreceptor degeneration, the C57BL/6 (B6 allele of which acts as a suppressor. Photoreceptors degenerate rapidly in Mertk-deficient animals homozygous for the 129P2/Ola (129 modifier allele, whereas animals heterozygous for B6 and 129 modifier alleles exhibit an unusual intermixing of degenerating and preserved retinal regions, with females more severely affected than males. Mertk-deficient mice homozygous for the B6 modifier allele display degeneration only in the far periphery, even at 8 months of age, and have improved retinal function compared to animals homozygous for the 129 allele. We genetically mapped the modifier to an approximately 2-megabase critical interval that includes Tyro3, a paralog of Mertk. Tyro3 expression in the outer retina varies with modifier genotype in a manner characteristic of a cis-acting expression quantitative trait locus (eQTL, with the B6 allele conferring an approximately three-fold higher expression level. Loss of Tyro3 function accelerates the pace of photoreceptor degeneration in Mertk knockout mice, and TYRO3 protein is more abundant in the retinal pigment epithelium (RPE adjacent to preserved central retinal regions of Mertk knockout mice homozygous for the B6 modifier allele. Endogenous human TYRO3 protein co-localizes with nascent photoreceptor outer segment (POS phagosomes in a primary RPE cell culture assay, and expression of murine Tyro3 in cultured cells stimulates phagocytic ingestion of POS. Our findings demonstrate that Tyro3 gene dosage modulates Mertk-associated retinal degeneration, provide strong evidence for a direct role for TYRO3 in RPE phagocytosis

  4. 不同融合节段后路减压椎间融合内固定术对邻近节段稳定性影响的影像学分析%Radiologic stability analysis of adjacent segments after different fusion segments of posterior lumbar interbody fusion

    Institute of Scientific and Technical Information of China (English)

    刘玉增; 海涌; 杨晋才; 关立

    2013-01-01

    Objective To investigate the radiologic stability of adjacent segments after single, double and triple fusion segments of posterior lumbar interbody fusion ( PLIF ). Methods All 45 patients who were treated by PLIF were divided into 3 groups, including group A of single segment, group B of double segments and group C of triple segments, with 15 patients in each group. The effects on the stability of adjacent segments after fusion were retrospectively analyzed. The preoperative and postoperative lumbar lordosis angle and range of motion ( ROM ) of upper adjacent segments were measured. Results The results showed the lumbar ROM was decreased in the latest follow-up when compared with that preoperatively by 10.4° in group A, 11.4° in group B and 16° in group C on average. And the ROM of adjacent segments was increased in the latest follow-up when compared that preoperatively by 2.1° in group A, 1.9° in group B and 8.1° in group C on average. The preoperative ROM of adjacent segments was ( 3.6±2.0 ) °, ( 8.4±5.5 ) ° and ( 5.0±4.5 ) ° in group A, group B and group C, and the postoperative ROM was ( 6.5±1.6 ) °, ( 9.8±9.5 ) ° and ( 13.0±7.6 ) ° respectively. The differences between the preoperative and postoperative ROM in each group were statistically signiifcant ( P<0.01 ), and the differences of the postoperative ROM among all groups were statistically signiifcant ( P<0.01 ). Conclusions With the adding of fusion segments, the ROM of adjacent segments also increases. Based on the preoperative lumbar lordosis angle, a modest recovery of the physiological lordosis angle is achieved during the operation. It is an effective method to maintain the stability of adjacent segments.%目的探讨单节段、双节段和三节段后路椎间融合器置入椎弓根内固定术( posterior lumbar interbody fusion,PLIF )对融合节段邻近节段稳定性的影响。方法回顾性单节段( A组),双节段( B组)和三节段( C组) PLIF,共45例,对融

  5. Comparison of angular displacement and stress of adjacent segment disc treated with semi-rigid and rigid fixation%半坚强与坚强内固定邻近节段腰椎间盘角位移及应力的比较

    Institute of Scientific and Technical Information of China (English)

    吕建华; 唐昭惠; 陈凯; 李明; 张秋林

    2016-01-01

    BACKGROUND:Theoreticaly, lumbar semi-rigid fixation can slow down the degeneration of adjacent segments, but there is stil a lack of biomechanical support. OBJECTIVE:To explore the biomechanical effect of semi-rigid fixation system, taking Isobar TTL for instance, on adjacent segment disc by means of finite element analysis. METHODS: The finite element models of USS and Isobar TTL were constructed by putting respective parameters into a validated L2-S5 lumbar model. The angular displacement and von Mises stress of adjacent segments were recorded when the models were subjected to 400 N preload and 7.5 N•m moment of forces under different conditions: flexion, extension, lateral bending and axial rotation. RESULTS AND CONCLUSION:The angular displacement and inter-vertebral disc stress of adjacent segments in the USS and Isobar TTL models were higher than those of an intact state in every condition. But the values in Isobar TTL model were lower than the USS model in varying degrees. Compared with the USS model, the decrease rates of angular displacement in Isobar TTL model for flexion, extension, left bending, right bending, left axial rotation and right axial rotation were 19.2%, 15.1%, 11.1%, 12.2%, 18.4% and 22.1%, respectively. The decrease rates of von Mises stress were 33.0%, 20.2%, 23.9%, 18.6%, 28.8% and 28.0%, respectively. The results suggested that the Isobar TTL, when compared with the USS, partialy reduced the angular displacement and inter-vertebral disc stress of adjacent segments.%背景:理论上腰椎半坚强内固定能够减缓邻近节段退变,但目前仍缺乏生物力学研究结果支持。目的:以Isobar TTL装置为例利用有限元方法分析半坚强内固定对邻近节段腰椎间盘生物力学的影响。方法:根据USS坚强内固定系统和Isobar TTL半坚强内固定系统的材料参数分别导入已通过验证的L2-S5腰骶椎模型,构建双节段固定的腰椎内固定模型,各施加垂直负荷为400 N

  6. On the computational complexity of degenerate unit distance representations of graphs

    CERN Document Server

    Kratochvil, Jan; Pisanski, Tomaz

    2010-01-01

    Some graphs admit drawings in the Euclidean k-space in such a (natu- ral) way, that edges are represented as line segments of unit length. Such drawings will be called k dimensional unit distance representations. When two non-adjacent vertices are drawn in the same point, we say that the representation is degenerate. The dimension (the Euclidean dimension) of a graph is defined to be the minimum integer k needed that a given graph has non-degenerate k dimensional unit distance representation (with the property that non-adjacent vertices are mapped to points, that are not distance one appart). It is proved that deciding if an input graph is homomorphic to a graph with dimension k >= 2 (with the Euclidean dimension k >= 2) are NP-hard problems.

  7. On the Computational Complexity of Degenerate Unit Distance Representations of Graphs

    Science.gov (United States)

    Horvat, Boris; Kratochvíl, Jan; Pisanski, Tomaž

    Some graphs admit drawings in the Euclidean k-space in such a (natural) way, that edges are represented as line segments of unit length. Such embeddings are called k-dimensional unit distance representations. The embedding is strict if the distances of points representing nonadjacent pairs of vertices are different than 1. When two non-adjacent vertices are drawn in the same point, we say that the representation is degenerate. Computational complexity of nondegenerate embeddings has been studied before. We initiate the study of the computational complexity of (possibly) degenerate embeddings. In particular we prove that for every k ≥ 2, deciding if an input graph has a (possibly) degenerate k-dimensional unit distance representation is NP-hard.

  8. Movement Feature of Adjacent Segments After Cervical Three-Segment Fusion%颈椎三节段融合术后相邻节段运动变化规律研究

    Institute of Scientific and Technical Information of China (English)

    薛清华; 刘伟强

    2011-01-01

    This article aims at investigating the rules of the motion of human cervical after 3 - segment fusion,with the help of a study 3D motion information collecting system. The motion information of 6 porcine cervical specimens in intact and fusion condition was collected ,and the motion range and angle of each segment were calculated. Through analyzing the movement feature ,we concluded that the quality of three-level fusion was slightly worse than that of two-level fusion, and the movement range was about to 30% of the intact state. In comparison of the two kinds of three-level fusion and three kinds of two-level fusion,we found that the motion compensation range was bigger in the former ones at each level. The quantitative reference and theory evidence raised from this study will give a great support to the operation of multi-level fusion of the human cervical.%为研究人体颈椎三节段融合后的运动规律,本文利用三维运动信息采集系统,获取了6具猪颈椎C2-T1标本在未损伤及两种三节段融合状态下的各个节段的运动信息,计算并得到各节段运动转角;再通过分析三节段融合的相关运动规律和特点,得出三节段融合质量略差于双节段融合效果,融合后的运动幅度可降低至融合前的30%左右;通过定量比较得出两种三节段融合相对于三种双节段融合,前、后相邻节段与其它节段融合状态的运动补偿幅度均有不同程度的增加.本研究为人体多节段融合临床手术提供了定量参考和理论依据.

  9. Adjacent Lumbar Disc Herniation after Lumbar Short Spinal Fusion

    Directory of Open Access Journals (Sweden)

    Koshi Ninomiya

    2014-01-01

    Full Text Available A 70-year-old outpatient presented with a chief complaint of sudden left leg motor weakness and sensory disturbance. He had undergone L4/5 posterior interbody fusion with L3–5 posterior fusions for spondylolisthesis 3 years prior, and the screws were removed 1 year later. He has been followed up for 3 years, and there had been no adjacent segment problems before this presentation. Lumbar magnetic resonance imaging (MRI showed a large L2/3 disc hernia descending to the L3/4 level. Compared to the initial MRI, this hernia occurred in an “intact” disc among multilevel severely degenerated discs. Right leg paresis and bladder dysfunction appeared a few days after admission. Microscopic lumbar disc herniotomy was performed. The right leg motor weakness improved just after the operation, but the moderate left leg motor weakness and difficulty in urination persisted.

  10. On Doubly Degenerate Quasilinear Parabolic Equations of Higher Order

    Institute of Scientific and Technical Information of China (English)

    Zhen Hai LIU

    2005-01-01

    We deal with the existence of periodic solutions for doubly degenerate quasilinear parabolic equations of higher order, which can degenerate, on a part of the boundary, on a segment in the interior of the domain and in time.

  11. 枢椎骨折合并相邻节段不稳的分型和手术治疗选择%The classification and surgical management for axis fracture complicated with adjacent segment instability

    Institute of Scientific and Technical Information of China (English)

    王雷; 柳超; 赵庆华; 刘铖祎; 田纪伟

    2012-01-01

    Objectives: To provide the classification of axis fracture complicated with adjacent segment instability and investigate its significance to surgical management. Methods: 47 patients(31 males and 16 females) with axis fractures from August 2003 to June 2011 with a mean age of 32 years(range, 19 to 59) were treated surgically and analyzed retrospectively. The Frankel scale was used to assesse neurofunction as following: 1 grade A, 2 grade B, 3 grade C and 5 grade D before surgery. The classification was determined according to the fracture type and stability of adjacent segment. Type A (21 cases): axis fracture with C1/2 instability; Type B(17 cases): axis fracture with C2/3 instability; Type C(9 cases): axis fracture with both C1/2 and C2/3 instability. Operations were performed as following: Type A, posterior atlantoaxial fixation plus anterior screw fixation for odontoid fracture; Type B, anterior disceetomy, fusion, and cervical plate fixation; Type C, posterior C1-C3 fixation or occipitocervical fusion when C1- C2 fusion was unavailable. JOA score was applied to e-valuate the therapeutic effect. The fracture healing, bone graft fusion and stability were observed on X-ray or CT scan. Results: All patients underwent surgery safely without spinal cord injury, cerebrospinal fluid leakage and vertebral artery injury. The average follow-up was 15 months(9-48 months). There was significant differ-ence(P<0.05) in JOA score between pre-operation(10.60±3.29) and post-operation(13.83±3.93), and the rate of improvement was 72.3%-90.8%, with the excellent to good rate of 98%. 1-2 degree improvement of neuro-function was achieved in all except 1 Frankel B. After operation, all patients were immobilized in a hard collar for 3 months. Fusion was achieved in 39 cases from 3 to 6 months(mean 4.5 months). X-ray verified no malposition of the screws. No instrument failure was noted during follow-up. Conclusions: Axis fracture complicated with adjacent segment instability should

  12. Surgical treatment of complicated atlas fracture combined with adjacent segment instability%复杂性枢椎骨折合并相邻节段不稳的外科治疗

    Institute of Scientific and Technical Information of China (English)

    王雷; 刘诚祎; 田纪伟; 赵庆华; 董双海; 夏天; 袁文

    2010-01-01

    目的 探讨复杂枢椎骨折合并相邻节段不稳的临床、影像学特点,提供合理的手术治疗策略.方法 回顾分析手术治疗且资料完整的21例枢椎骨折患者,男14例,女7例;平均年龄34岁.根据枢椎骨折的类型及其相邻寰枢关节、C2/3椎间的稳定情况,分别采用以下手术方式:(1)前路C2/3椎间盘切除及植骨、颈前路钢板固定;(2)齿状突螺钉固定;(3)后路C1~2椎弓根、颈椎侧块螺钉固定或联合前后路手术,稳定上颈椎.结果 21例全部获得6~36个月随访(平均12个月),术后佩戴颈围3个月,3个月均获得骨性融合,颈椎伸屈侧位片显示颈椎稳定,无内固定松动、脱出及断裂,无椎动脉损伤、神经损伤、脑脊液漏及切口感染等手术并发症.5例脊髓损伤神经功能恢复良好.结论 对于枢椎骨折,在确定骨折的类型及准确判断相邻寰枢关节、C2/3稳定性受破坏程度的基础上,通过手术治疗,可取得良好的疗效.%Objective To study the clinical and radiographic characteristics of complicated axis fractures combined with adjacent segment instability and explore reasonable surgical treatment strategy. Methods A retrospective study was performed on 21 patients with axis fractures treated from August 2003 to June 2009. There were 14 males and 7 females at mean age of 34 years. The treatment strategy was based on the fracture type and the stabilities of adjacent atlantoaxial joint and intervertebral C2/3.Treatment strategies included anterior C2/3 interbody discectomy and fusion, anterior cervical plate internal fixation, odontoid screw fixation, posterior C1-2 pedicle screw fixation, cervical lateral mass screw fixation or combined anteroposterior approach. Results All patients were immobilized in a hard collar for thee months and followed up for 6-36 months (average 12 months), which showed bony fusion and cervical stability, with no intraoperative surgery-related complications such as loosening

  13. 颈前路螺钉矢状角对相邻节段影响的生物力学研究%A biomechanical study of effects of anterior cervical screw sagittal angle on adjacent segments

    Institute of Scientific and Technical Information of China (English)

    陆兆华; 赵峰; 苏维成; 赵晓勇; 赵彦涛; 李忠海

    2015-01-01

    目的:采用三维有限元方法分析颈前路螺钉矢状角( sagittal screw angle,SSA )对相邻节段生物力学的影响,判断 SSA 是否是引起邻近节段病的危险因素。方法基于健康成年男性 C3~7节段 CT 图像建立颈椎有限元模型。模拟颈前路 C5椎体次全切除、C4~6钢板内固定术,按照 SSA (0°,0°)(5°,5°)(10°,10°)分别建模,计算在不同的 SSA 下,C4上终板、C6下终板以及钢板的应力变化情况。结果 C4上终板在前屈时前方区域所受应力最大,随着 SSA 的增加,C4上终板整体所受的最大应力逐渐减小,SSA 增大10°后,C4上终板前方区域的最大应力减小12.67%。C6下终板在前屈时前方区域所受应力最大,随着 SSA 的增加,C6下终板整体所受的最大应力逐渐减小,SSA 增大10°后,C6下终板前方区域的最大应力减小7.99%。钢板在前屈和后伸时其最大应力均较集中于中部区域,并且显著高于上部及下部区域,随着 SSA 的增加,钢板受到的应力会逐渐增加。结论在颈椎前路融合内固定手术中,增大 SSA,可增加钢板承受的应力,同时降低邻近节段终板的应力,从而减少邻近节段病的发生。%Objective To analyze effects of different screw sagittal angles ( SSA ) on the stress of adjacent levels, and determine whether SSA is a risk factor of adjacent segment disease ( ASD ).Methods A three-dimensional ifnite element ( FE ) model of intact C3-7 segments was developed and validated based on healthy males. C5 anterior corpectomy and allograft interbody fusion with a rigid anterior screw-plate construction was created from C4 to C6. Three additional FE models were developed from the fusion model corresponding to 3 different combinations of SSA: ( 0°, 0° ), ( 5°, 5° ), and ( 10°, 10° ). Von Mises stress on the C4 superior end-plate, C6 inferior end-plate and screw-plate were analyzed.Results The largest stress

  14. 胸腰椎相邻节段矢状曲度X线片不同测量方法的对比研究%Comparative study of radiographic measurements on sagittal plane curves in adjacent segments of thoracolumbar spine

    Institute of Scientific and Technical Information of China (English)

    吴超; 谭伦; 林旭; 黄迅; 罗晓中

    2011-01-01

    Objective:To compare three methods on measuring sagittal plane curves in adjacent segments of thoracolumbar spine and to provide radiographic evidence for clinical practice.Method:42 times of thoracolumbar lateral views at varied postures were performed on 6 dried spine specimen and standard standing lateral views were obtained from 79 normal adults.The sagittal angle by distortion compensated roentgen analysis (DCRA method),the sagittal angle defined by two vertical lines perpendicular to the lines parallel to the superior endplate of above vertebra and the inferior endplate of below adjacent vertebral body (Cobbl method),the sagittal angle defined by two vertical lines perpendicular to the lines parallel to the superior endplate of above vertebra and the superior endplate of below adjacent vertebral body (Cobb2 method)were used to measure sagittal plane curves.All results were reviewed statistically.Result:There was statistical significance among the three measurements for clockwise or counterclockwise posture for spine specimen (P<0.05),while no statistical significance among 6 specimens at different postural lateral view by using DCRA method (P>0.05).There was statistical significance for clockwise or counterclockwise posture by using Cobbl method and Cobb2 method (P<0.05).There was no statistical significance among the three measurements of sagittal plane curves for adjacent segments for standard standing posture in normal adults (P>0.05).Conclusion:DCRA method is accurate for measuring sagittal plane curves,different orientation has no impact on measurement,while vertebral rotation influences the measurement significantly by using Cobbl and cobb2 methods.%目的:对比研究X线片上3种测量胸腰椎相邻节段矢状曲度方法的准确性,为临床应用提供放射学依据.方法:选取脊柱干燥标本共计6具,以不同投照方式行胸腰椎侧位X线摄片共计42次.选择79例正常人行站立位标准侧位X线摄片.将上述资

  15. Biomechanical testing of adjacent double segment lumbar fractures treated with the spinal external fixator%脊柱外固定器治疗相邻双节段腰椎骨折的生物力学测试*★

    Institute of Scientific and Technical Information of China (English)

    易国良; 宋西正; 王文军; 姚女兆

    2013-01-01

    normal group (P < 0.01). Compared with traditional internal fixation, the immediate stability index of the spinal external fixation in treating adjacent double segment burst fractures was equal. Both two fixation methods could increase the range of motion of the adjacent upper vertebra under lateral bending and rotation. But the spinal external fixation could not increase the range of motion of adjacent upper vertebrae under flexion and extension.

  16. [Hepatolenticular degeneration].

    Science.gov (United States)

    Zudenigo, D; Relja, M

    1990-01-01

    Hepatolenticular degeneration (Wilson's disease) is a hereditary disease in which metabolic disorder of copper leads to its accumulation in the liver, brain, cornea and kidneys with consequent pathologic changes in those organs. Hereditary mechanism of the disease is autosomal recessive with prevalence of 30-100 per 1,000,000 inhabitants. Etiology of this disease is not yet explained. There are two hypotheses. The first one is that it is the disorder of ceruloplasmine metabolism caused by insufficient synthesis of normal ceruloplasmine, or synthesis of functionally abnormal ceruloplasmine. The second one is: the block of copper biliar excretion which is the consequence of the liver lysosomes functional defect. Pathogenetic mechanism of disease is firstly long-term accumulation of copper in the liver, and later, when the liver depo is full, its releasing in circulation and accumulation in the brain, cornea, kidneys and bones, which causes adequate pathologic changes. Toxic activity of copper is the consequence of its activity on enzymes, particularly on those with -SH group. There are two basic clinical forms of the disease: liver disease or neurologic disease. Before puberty the liver damage is more frequent, while in adolescents and young adults neurologic form of the disease is usual. The liver disease is nonspecific and characterized by symptoms of cirrhosis and chronic aggressive hepatitis. The only specificity is hemolytic anemia which, in combination with previous symptoms, is important for diagnosis of the disease. Neurologic symptoms are the most frequent consequence of pathologic changes in the basal ganglia. In our patients the most frequent symptoms were tremor (63%); dysarthria, choreoathetosis and rigor (38%); ataxia and mental disorders (31%); dysphagia and dystonia (12%), diplopia, hypersalivation, nystagmus and Babinski's sign (6%). Among pathologic changes in other tissues and organs the most important is the finding of Kayser-Fleischer ring in the

  17. Mechanisms of axon degeneration: from development to disease.

    Science.gov (United States)

    Saxena, Smita; Caroni, Pico

    2007-10-01

    Axon degeneration is an active, tightly controlled and versatile process of axon segment self-destruction. Although not involving cell death, it resembles apoptosis in its logics. It involves three distinct steps: induction of competence in specific neurons, triggering of degeneration at defined axon segments of competent neurons, and rapid fragmentation and removal of the segments. The mechanisms that initiate degeneration are specific to individual settings, but the final pathway of pruning is shared; it involves microtubule disassembly, axon swellings, axon fragmentation, and removal of the remnants by locally recruited phagocytes. The tight regulatory properties of axon degeneration distinguish it from passive loss phenomena, and confer significance to processes that involve it. Axon degeneration has prominent roles in development, upon lesions and in disease. In development, it couples the progressive specification of neurons and circuits to the removal of defined axon branches. Competence might involve transcriptional switches, and local triggering can involve axon guidance molecules and synaptic activity patterns. Lesion-induced Wallerian degeneration is inhibited in the presence of Wld(S) fusion protein in neurons; it involves early local, and later, distal degeneration. It has recently become clear that like in other settings, axon degeneration in disease is a rapid and specific process, which should not be confused with a variety of disease-related pathologies. Elucidating the specific mechanisms that initiate axon degeneration should open up new avenues to investigate principles of circuit assembly and plasticity, to uncover mechanisms of disease progression, and to identify ways of protecting synapses and axons in disease.

  18. [Case-control study on Zero-profile implant for anterior cervical discectomy and fusion and conventional cage plate internal fixation for the treatment of single segmental cervical intervertebral disc herniation].

    Science.gov (United States)

    Shao, Hai-yu; Zhang, Jun; Yang, Di; Chen, Jin-ping; Huang, Ya-zeng

    2016-06-01

    To compare clinical efficacy of Zero-profile implant for anterior cervical discectomy and fusion and conventional titanium plate with cage internal fixation for the treatment of single segmental cervical intervertebral disc herniation. From August 2011 to March 2014, clinical data of 139 patients with single cervical disc herniation treated with anterior cervical discectomy and interbody fusion with internal fixation were retrospectively analyzed. The patients were divided into two groups according to its operation method. There were 63 patients in group A which performed anterior discectomy and interbody fusion with Zero-profile;76 patients in group B which performed anterior cervical discectomy and cage plate internal fixation. JOA score and Odom functional rating between two groups were compared before and after operation. Videofluorographic swallowing study (VFSS) were used to evaluate thickness of prevertebral soft tissue. Bazaz dysphagia score were used to assess incidence of dysphagia. Postoperative AP X-ray and CT of cervical vertebra at 12 months were applied for evaluating bone graft fusion. Postoperative MRI was applied for evaluating the incidence of adjacent segment degeneration. Blood loss,operative time, preoperative and postoperative JOA score, Odom functional rating and VFSS score, Bazaz score, fusion rate between vertebral bodies and incidence of adjacent segment degeneration were compared between two groups. There were no statistical meaning between two groups in JOA score, Odom functional rating before and after operation (P > 0.05); and no significant meaning in VFSS score between two groups before operation (P > 0.05); There were no significant difference in operative time and blood loss. There was statistical meaning in VFSS, Bazaz dysphagia score at 2 days, and 6 months after operation (P 0.05). Eight patients (12.7%) in group A occurred adjacent segment degeneration and 19 patients (25%) in group B occurred adjacent segment degeneration

  19. Motor axon excitability during Wallerian degeneration

    DEFF Research Database (Denmark)

    Moldovan, Mihai; Alvarez, Susana; Krarup, Christian

    2008-01-01

    , action potential propagation and structural integrity of the distal segment are maintained. The aim of this study was to investigate in vivo the changes in membrane function of motor axons during the 'latent' phase of Wallerian degeneration. Multiple indices of axonal excitability of the tibial nerve...

  20. Wet Macular Degeneration

    Science.gov (United States)

    ... macular degeneration Overview By Mayo Clinic Staff Wet macular degeneration is a chronic eye disease that causes blurred vision or a blind spot in your visual field. It's generally caused by abnormal blood vessels that leak fluid or blood into ... macular degeneration is one of two types of age-related ...

  1. IMMEDIATE RECIPROCAL CHANGES AT ADJACENT LEVEL FOLLOWING SINGLE-LEVEL ALIF

    Directory of Open Access Journals (Sweden)

    Enrique Vargas Uribe

    2015-12-01

    Full Text Available Objective : To assess the segmental sagittal parameters and the adjacent mobile segment after interbody fusion by anterior approach in single-level L5-S1. Methods : Retrospective study. Inclusion: Interbody fusion by anterior approach (10°/15° angle, due to DDD, low-grade spondylolisthesis and/or stenosis without prior lumbar fusion. Thirty-five cases were included (25 women; mean age 47±15 years. Analysis of lumbar radiographs were performed preoperatively and 3 months after surgery. The following parameters were evaluated: lumbar lordosis; segmental lordosis L4-L5 and L5-S1; sacral and L5 slope. Two independent evaluators made the measurements. Student's t test was used. Results : There was correction of lordosis at the L5-S1 level, from an average of 19° prior to surgery to 28° three months after surgery (p<0.001. It was observed reduction of the L4-L5 angle from 17° to 14° (p <0.001. Moreover, there was a small, but statistically significant, reduction of L5 inclination from 17 ° to 13 ° (p=0.007 and increase in the sacral slope from 37° to 40° (p=0.002. The change of total lumbar lordosis was not significant: 52° versus 53° (p=0.461. Before surgical correction, lordosis of the L5-S1 level contributed, on average, 37% of lumbar lordosis, and after, 54% (p<0.001. The L4-L5 level accounted for 34% and decreased to 24% (p<0.001. Conclusion : In the group studied, it was observed a decrease in lordosis of the adjacent mobile level following the treatment of the degenerate level by anterior interbody fusion and concomitant increase in lordosis.

  2. Síndrome do disco adjacente à fusão (Síndrome de Transição na coluna cervical: resultados segundo critérios clínicos e radiológicos Síndrome del disco adyacente a la fusión (Síndrome de Transición en la columna cervical Adjacent segment disease (Transitional Syndrome in cervical spine: clinical and radiological results

    Directory of Open Access Journals (Sweden)

    Alexandre Meluzzi

    2010-03-01

    adyacente, se mostraron como los grandes factores de riesgo para el seguimiento.OBJECTIVE: the objective of this study was to identify the occurrence of adjacent disc syndrome secondary to intervertebral fusion in the cervical segment, and the predictors of outcome. METHODS: the medical records and imaging studies of 209 patients undergoing surgical treatment of cervical degenerative disease, with 169 cases treated through anterior approach and 40 cases through the posterior approach, at the HC-FMUSP from March 1993 to January 2007. Clinical evaluation was quantified by the scale of Japanese Orthopaedic Association (JOA, with an average follow-up of 80 months. The radiological analysis was based on the criteria of instability by White and Panjabi in all cases. The degeneration was measured by the scale of Kellgren before and after surgery. RESULTS: overall, the syndrome of adjacent disc was diagnosed in 30 cases (17.75%, with a mean time interval of incidence of 28.5 months after the merger, or 2.9 cases per year. There was an increase in degenerative changes in X-rays at levels adjacent to anterior fusion in 41.42% and 52.5% for the posterior without fusion, evaluated by the scale of Kellgren, the degeneration rate of 6.7% per annum, with no correlation with clinical changes. CONCLUSIONS: changes in physiological sagittal alignment of the spine and their severity predispose to the development of the syndrome. There was no incidence of the syndrome in cases of pseudoarthrosis or methacrylate, therefore, where there was a merger. The use of decompression and fusion, anterior, is associated with the possibility of developing a new framework for myeloradiculopathy in the postoperative period. Merger at a level that involve the fifth or sixth cervical vertebra, fixation with plates and pre-existing radiographic evidence of disc degeneration adjacent were factors of high risk for its emergence.

  3. OVERLOAD STUDY ON ADJACENT DISC AFTER ARTHRODESIS IN THORACOLUMBAR FRACTURES

    Directory of Open Access Journals (Sweden)

    GUSTAVO SERRA REINAS

    Full Text Available ABSTRACT Objective: To analyze the degeneration of the adjacent disc after arthrodesis due to thoracolumbar fractures. Methods: Eighty-three patients who underwent posterolateral arthrodesis in thoracolumbar levels had their x-rays analyzed for degeneration of adjacent discs to the arthrodesis. The disc spaces were classified by the UCLA scale. Results: Of the 83 patients evaluated, 66 were males (79% and 18 females (21%, with a mean age of 35.5 years. The mean follow-up period was 40 months. As the fractures 75% were between T12 and L2 (p<0.001, being of the A3 type in 65% of the cases (p<0.001. The most common mechanism of injury, accounting for 50% of the cases (p<0.001, was fall from height. Only 6% of the superior discs and 12% of the inferior ones showed some degree of degeneration. No patient underwent a new surgical approach. Conclusion: The incidence of degeneration on adjacent disc in patients after arthrodesis resulting from fractures ranged from 6% to 12% with an average follow-up of 40 months.

  4. Is Preventative Long-Segment Surgery for Multi-Level Spondylolysis Necessary? A Finite Element Analysis Study.

    Directory of Open Access Journals (Sweden)

    Jianqiang Mo

    Full Text Available For multi-level spondylolysis patients, surgeons commonly choose to fix all the segments with pars interarticularis defect even those without slippage and not responsible for clinical symptoms. In this study, we tried to study the necessity of the preventative long-segment surgery for the defected segment without slippage in treatment of multi-level spondylolysis patients from a biomechanical perspective.We established a bi-level spondylolysis model with pars defects at L4 and L5 segments, and simulated posterior lumbar interbody fusion (PLIF and pedicle screw fixation at L5-S1 level. Then we compared the biomechanical changes at L4 segment before and after surgery in neutral, flexion, extension, lateral bending and axial rotation position.The stress on L4 pars interarticularis was very similar before and after surgery, and reached the highest in axial rotation. The L3-L4 intradiscal pressure was almost the same, while L4-L5 intradiscal pressure changed a little in lateral bending (increase from 1.993 to 2.160 MPa and axial rotation (decrease from 1.639 to 1.307 MPa after surgery. The PLIF surgery caused a little increase of range of motion at adjacent L4-L5 and L3-L4 levels, but the change is very tiny (1 degree.The PLIF surgery will not cause significant biomechanical change at adjacent segment with pars defect in multi-level spondylolysis. On the contrary, excessive long-segment surgery will damage surrounding soft tissues which are important for maintaining the stability of spine. So a preventative long-segment surgery is not necessary for multi-level spondylolysis as long as there are no soft tissue degeneration signs at adjacent level.

  5. The outcome and influence of artificial cervical disc replacement on adjacent non-responsible segment instability in patients with cervical spondylosis%人工颈椎间盘置换的疗效及其对相邻非责任节段失稳的影响

    Institute of Scientific and Technical Information of China (English)

    种涛; 俞兴; 徐林; 贾育松; 李春根; 毕连涌; 柳根哲

    2012-01-01

    Objectives: To investigate the clinical efficacy and imaging results of the adjacent segment instability in patients with cervical spondylosis treated by Bryan cervical disc replacement. Methods: A retrospective review was performed on 9 cases suffering from adjacent segment instability before surgery. All 9 cases underwent Bryan artificial cervical disc arthoplasty and were followed up from July 2005 to January 2009 in our hospital. There were 4 males and 5 females with an average age of 33.5 years (range, 26-43 years). Japanese Orthopaedic Association(JOA) score was 10.16±3.17(7-13), and visual analogue pain scale(VAS) was 4.3±2.7(l-7) before surgery. All patients underwent cervical flexion and extension plain film and cervical MRI before surgery. Imaging instability was confirmed in the adjacent segment, which was asymptomatic. C4/5 replacement, 1 cases instability in C5/6; C5/6 replacement 4 cases, 3 cases instability in C4/5, 1 cases instability in C6/7; C6/7 replacement, 2 cases instability in C5/6. The double segment replacement 2 cases, each 1 cases instability in C4/5, C5/6 and C5/6, C6/7, which both are adjacent to the head-end segment. Clinical outcome of surgery was evaluated by JOA, neck pain VAS and Odom before surgery and at 1 week, 3, 6, 12, 24, 36 months after surgery respectively; the range of motion(ROM) of the surgical segment, adjacent unstable segment, C2-C7 and cervical malalignment were assessed by cervical dynamic X-ray before operation and 3, 6, 12, 24, 36 months after surgery. Results: The JOA score, neck pain VAS were improved significantly at each follow-up 3 months later after surgery compared with those of preoperation, difference was statistically significant(P0.05), while decreased significantly at 24 and 36 months(P<0.05). ROM of implanted segment and cervical curve at 24 and 36 months after operation increased significantly(P<0.05) compared with preoper-ative ones. The postoperative ROM of C2-C7 remained unchanged at each follow

  6. The correlation analysis of the cervical spine alignment, flexion ROM of adjacent segments with the spinal cord atrophy in Hirayama disease%平山病患者颈椎曲度和相邻节段椎体屈曲度与脊髓萎缩的相关性

    Institute of Scientific and Technical Information of China (English)

    刘鑫; 孙宇

    2013-01-01

    curvature,flexion ROM of adjacent segment with spinal cord atrophy of Hirayama disease,and to provide rationale for its surgical management.Methods:36 consecutive patients underwent flexion X-ray and neutral position cervical MRI.The radiological mcasurement included the cervical spine alignment from C2 to C7 and the arc chord distance (ACD) by the Borden's method,flexion ROM of adjacent segments by calculating the difference between neutral and flexion position of Cobb angle defined as the tangent of the posterior body line of every two adjacent segments from C3-C7,observing spinal cord atrophy on sagittal position MRI and measuring the cross-sectional area of spinal from C3-C7 on neutral position cervical MRI.According to the ACD of cervical curvature,all patients were divided into 4 groups:7mm≤ACD≤17mm,normal cervical spine alignment; 1mm<ACD<7mm,straight or mild kyphosis;-4mm<ACD≤1mm,moderate kyphosis; ACD≤-4mm,severe kyphosis.The correlation analysis was performed between the adjacent vertebral flexion ROM and the cross-sectional area of corresponding cervical spinal cord on neutral position MRI.Results:In the 36 patients,normal cervical alignment accounted for 8 cases,straight or mild kyphosis for 13 cases; moderatc or severe kyphosis for 15 cases,of these 15 patients,14 had apex of kyphosis on C5 and 1 on C44.14 patients showed lower spinal cord atrophy on neutral MRI.13/28 cases with cervical straight or ankylosis presented with spinal cord compression was much higher than 1/8 of cases with normal cervical alignment (P<0.05).There were significant differences among flexion ROM of adjacent segments from C3 to C7 (P<0.05),with a higher flexion ROM of C5-C6 & C6-C7.Significant differences also existed between the cross-sectional area of spinal cord form C3 to C7 (P<0.05),with the lowest value at C5-C6 & C6-C7.Flexion ROM of adjacent segments was negatively correlated with the corresponding cross-sectional area of spinal cord in neutral MRI(r=-0

  7. Degenerate Euler zeta function

    OpenAIRE

    Kim, Taekyun

    2015-01-01

    Recently, T. Kim considered Euler zeta function which interpolates Euler polynomials at negative integer (see [3]). In this paper, we study degenerate Euler zeta function which is holomorphic function on complex s-plane associated with degenerate Euler polynomials at negative integers.

  8. Biomechanical study of intervertebral disc degeneration

    OpenAIRE

    González Guitiérrez, Ramiro Arturo

    2012-01-01

    Degeneration and age affect the biomechanics of the intervertebral disc, by reducing its stiffness, flexibility and shock absorption capacities against daily movement and spinal load. The biomechanical characterization of intervertebral discs is achieved by conducting mechanical testing to vertebra-disc-vertebra segments and applying axial, shear, bend and torsion loads, statically or dynamically, with load magnitudes corresponding to the physiological range. However, traditional testing does...

  9. Biomechanical study of intervertebral disc degeneration

    OpenAIRE

    González Guitiérrez, Ramiro Arturo

    2012-01-01

    Degeneration and age affect the biomechanics of the intervertebral disc, by reducing its stiffness, flexibility and shock absorption capacities against daily movement and spinal load. The biomechanical characterization of intervertebral discs is achieved by conducting mechanical testing to vertebra-disc-vertebra segments and applying axial, shear, bend and torsion loads, statically or dynamically, with load magnitudes corresponding to the physiological range. However, traditional testing does...

  10. Pelvic incidence-lumbar lordosis mismatch results in increased segmental joint loads in the unfused and fused lumbar spine.

    Science.gov (United States)

    Senteler, Marco; Weisse, Bernhard; Snedeker, Jess G; Rothenfluh, Dominique A

    2014-07-01

    Symptomatic adjacent segment disease (ASD) has been reported to occur in up to 27 % of lumbar fusion patients. A previous study identified patients at risk according to the difference of pelvic incidence and lordosis. Patients with a difference between pelvic incidence and lumbar lordosis >15° have been found to have a 20 times higher risk for ASD. Therefore, it was the aim of the present study to investigate forces acting on the adjacent segment in relation to pelvic incidence-lumbar lordosis (PILL) mismatch as a measure of spino-pelvic alignment using rigid body modeling to decipher the underlying forces as potential contributors to degeneration of the adjacent segment. Sagittal configurations of 81 subjects were reconstructed in a musculoskeletal simulation environment. Lumbar spine height was normalized, and body and segmental mass properties were kept constant throughout the population to isolate the effect of sagittal alignment. A uniform forward/backward flexion movement (0°-30°-0°) was simulated for all subjects. Intervertebral joint loads at lumbar level L3-L4 and L4-L5 were determined before and after simulated fusion. In the unfused state, an approximately linear relationship between sagittal alignment and intervertebral loads could be established (shear: 0° flexion r = 0.36, p < 0.001, 30° flexion r = 0.48, p < 0.001; compression: 0° flexion r = 0.29, p < 0.01, 30° flexion r = 0.40, p < 0.001). Additionally, shear changes during the transition from upright to 30° flexed posture were on average 32 % higher at level L3-L4 and 14 % higher at level L4-L5 in alignments that were clinically observed to be prone to ASD. Simulated fusion affected shear forces at the level L3-L4 by 15 % (L4-L5 fusion) and 23 % (L4-S1 fusion) more for alignments at risk for ASD. Higher adjacent segment shear forces in alignments at risk for ASD already prior to fusion provide a mechanistic explanation for the clinically observed correlation between PILL mismatch and rate

  11. The biomechanical effects on adjacent segments after two-level ACDF with reduced lordosis%颈椎前凸角度减小对融合术后邻近节段影响的生物力学研究

    Institute of Scientific and Technical Information of China (English)

    逄川; 海涌; 杨晋才; 刘玉增; 裴葆青; 李慧; 祖丹; 朱罡; 夏旭光

    2016-01-01

    on adjacent segments of anterior cervical discectomy and fusion (ACDF).Methods 6 adult human cervical spine specimens (C2-C7) were tested under the following 3 conditions:intact cervical spine group,C4-6 ACDF with normal lordosis group,C4-6 ACDF with reduced lordosis group.The specimens were tested in flexion,extension,bending and rotation on the spine 3D motion experiment system.The Cobb angle,overall range of motion (ROM),ROM and loads of facet joints at adjacent segments were measured.Results The lordosis Cobb angle was 13.5°±4.1 ° in intact cervical spine group,15.7°±4.6° in C4-6 ACDF with normal lordosis group,9.0°±4.0° in C4-6 ACDF with reduced lordosis group,respectively.After operation the overall ROM of specimens reduced in flexion,extension,bending and rotation,but the ROM of upper and lower adjacent segments increased.The ROM of upper segments (C3-4) in flexion and extension,as well as that of lower segments (C6-7) in flexion,extension and rotation,had significant difference.The extension ROM of upper segment (C3-4) of C4-6 ACDF with reduced lordosis group was found greater than that of C4-6 ACDF with normal lordosis group and the flexion and extension ROM at lower segment (C6-7) of C4-6 ACDF with reduced lordosis group were also greater.Increased max and average stress on C3-4 facet joints was observed in all the 4 types of motion after ACDF and the differences in extension and bending were statistically significant.Comparing C4-6 ACDF with reduced lordosis group and C4-6 ACDF with normal lordosis group,a stress decreasing trend was observed along with the reduced lordosis angle but had no significant difference.Conclusion After 2 level ACDF on cervical spine specimens,ROM of adjacent segments and stress on facet joints increased.The ROM of specimens with reduced lordosis is higher than those with normal lordosis,which may accelerate ASD.

  12. Hyaline cartilage degenerates after autologous osteochondral transplantation.

    Science.gov (United States)

    Tibesku, C O; Szuwart, T; Kleffner, T O; Schlegel, P M; Jahn, U R; Van Aken, H; Fuchs, S

    2004-11-01

    Autologous osteochondral grafting is a well-established clinical procedure to treat focal cartilage defects in patients, although basic research on this topic remains sparse. The aim of the current study was to evaluate (1) histological changes of transplanted hyaline cartilage of osteochondral grafts and (2) the tissue that connects the transplanted cartilage with the adjacent cartilage in a sheep model. Both knee joints of four sheep were opened surgically and osteochondral grafts were harvested and simultaneously transplanted to the contralateral femoral condyle. The animals were sacrificed after three months and the received knee joints were evaluated histologically. Histological evaluation showed a complete ingrowth of the osseous part of the osteochondral grafts. A healing or ingrowth at the level of the cartilage could not be observed. Histological evaluation of the transplanted grafts according to Mankin revealed significantly more and more severe signs of degeneration than the adjacent cartilage, such as cloning of chondrocytes and irregularities of the articular surface. We found no connecting tissue between the transplanted and the adjacent cartilage and histological signs of degeneration of the transplanted hyaline cartilage. In the light of these findings, long-term results of autologous osteochondral grafts in human beings have to be followed critically.

  13. Experimental Tape Casting of Adjacently Graded Materials for Magnetic Refrigeration

    DEFF Research Database (Denmark)

    Bulatova, Regina

    graded thin films. The motivation to create such adjacently segmented structures stemmed from a search of material and a materials design alternative to the expensive rare earth element gadolinium which is widely used as a magnetic regenerator in the emerging magnetic refrigeration technology...

  14. Degenerate Density Perturbation Theory

    CERN Document Server

    Palenik, Mark C

    2016-01-01

    Fractional occupation numbers can be used in density functional theory to create a symmetric Kohn-Sham potential, resulting in orbitals with degenerate eigenvalues. We develop the corresponding perturbation theory and apply it to a system of $N_d$ degenerate electrons in a harmonic oscillator potential. The order-by-order expansions of both the fractional occupation numbers and unitary transformations within the degenerate subspace are determined by the requirement that a differentiable map exists connecting the initial and perturbed states. Using the X$\\alpha$ exchange-correlation (XC) functional, we find an analytic solution for the first-order density and first through third-order energies as a function of $\\alpha$, with and without a self-interaction correction. The fact that the XC Hessian is not positive definite plays an important role in the behavior of the occupation numbers.

  15. Degenerate density perturbation theory

    Science.gov (United States)

    Palenik, Mark C.; Dunlap, Brett I.

    2016-09-01

    Fractional occupation numbers can be used in density functional theory to create a symmetric Kohn-Sham potential, resulting in orbitals with degenerate eigenvalues. We develop the corresponding perturbation theory and apply it to a system of Nd degenerate electrons in a harmonic oscillator potential. The order-by-order expansions of both the fractional occupation numbers and unitary transformations within the degenerate subspace are determined by the requirement that a differentiable map exists connecting the initial and perturbed states. Using the X α exchange-correlation (XC) functional, we find an analytic solution for the first-order density and first- through third-order energies as a function of α , with and without a self-interaction correction. The fact that the XC Hessian is not positive definite plays an important role in the behavior of the occupation numbers.

  16. Vortices as degenerate metrics

    CERN Document Server

    Baptista, J M

    2012-01-01

    We note that the Bogomolny equation for abelian vortices is precisely the condition for invariance of the Hermitian-Einstein equation under a degenerate conformal transformation. This leads to a natural interpretation of vortices as degenerate hermitian metrics that satisfy a certain curvature equation. Using this viewpoint, we rephrase standard results about vortices and make some new observations. We note the existence of a conceptually simple, non-linear rule for superposing vortex solutions, and we describe the natural behaviour of the L^2-metric on the moduli space upon certain restrictions.

  17. A study of retrograde degeneration of median nerve forearm ...

    African Journals Online (AJOL)

    Mona Mokhtar El Bardawil

    2013-10-22

    Oct 22, 2013 ... forearm segment in patients with CTS and its relation to variable severity of CTS in Egyptian patients. Patients ... Retrograde degeneration is not related to grade of severity of CTS. .... dominant hand using NEUROPACK 2 Electroneuromyog- ... was evaluated using Fisher Exact and Monte Carlo test.18,19.

  18. Kraepelin and degeneration theory.

    Science.gov (United States)

    Hoff, Paul

    2008-06-01

    Emil Kraepelin's contribution to the clinical and scientific field of psychiatry is recognized world-wide. In recent years, however, there have been a number of critical remarks on his acceptance of degeneration theory in particular and on his political opinion in general, which was said to have carried "overtones of proto-fascism" by Michael Shepherd [28]. The present paper discusses the theoretical cornerstones of Kraepelinian psychiatry with regard to their relevance for Kraepelin's attitude towards degeneration theory. This theory had gained wide influence not only in scientific, but also in philosophical and political circles in the last decades of the nineteenth century. There is no doubt that Kraepelin, on the one hand, accepted and implemented degeneration theory into the debate on etiology and pathogenesis of mental disorders. On the other hand, it is not appropriate to draw a simple and direct line from early versions of degeneration theory to the crimes of psychiatrists and politicians during the rule of national socialism. What we need, is a differentiated view, since this will be the only scientific one. Much research needs to be done here in the future, and such research will surely have a significant impact not only on the historical field, but also on the continuous debate about psychiatry, neuroscience and neurophilosophy.

  19. Impact of graft height on zygapophyseal joint pressure and range of motion adjacent to segment following cervical anterior fusion%颈椎前路融合术中植骨块的高度对邻近节段关节突压力及椎间位移的影响

    Institute of Scientific and Technical Information of China (English)

    罗春山; 欧阳北平; 梁栋柱; 陆廷盛; 姚书耽; 赵国权

    2016-01-01

    Objective To discuss impact of graft height on zygapophyseal joint pressure and range of motion of adjacent segments following the cervical anterior fusion and to guide the choice of optimal graft height in clinic. Methods Eight fresh-frozen human cadaveric cervical spines were used in this series, specimens were tested in five conditions, normal(specimens with intact discs)and different graft height(120%, 140%,160%of mean height) after Smith-Robinson discectomy between the fifth and sixth cervical vertebrae. Each specimens were subjected to flexion-extension. Lateral bending and axial rotation in material test system (BOSE ELECTROFORCE) were adopted to measure zygapophyseal joint pressure and rotation of the fourth to fifth segments and the sixth to seventh segments. Finally, The data for each state was used to determine the statistical significance of differences. Results The height of bone graft had little effect on the zygapophysial joints pressure values in neutral position with no statistical significance noted among each groups(P>0.05); The zygapophysial joints pressure value was the highest increase in extension position,but 120%M increased minimum of zygapophysial joints pressure value, and statistical significance were noted among each groups(P0.05), and statistical significance were noted in others groups(P0.05). Conclusion The appropriate graft height after single discectomy may be 120%mean height.%目的:探讨颈椎前路融合术中植骨块的高度对邻近节段关节突压力及活动度的影响,为临床上选择适宜的植骨高度提供依据。方法采用8例新鲜成人尸体颈椎标本,对完整状态,C5/6节段椎间隙减压术后(100%M、120%M、140%M、160%M)5组,于BOSE机加载下行三维运动,并测量颈C4/5,C6/7关节突压力值及C4/5,C6/7三维运动范围;最后将结果行多重比较分析。结果中立位状态下,关节突压力值各组无显著差异,P>0.05;后伸状态下,关节突压力

  20. X-82 to Treat Age-related Macular Degeneration

    Science.gov (United States)

    2017-01-12

    Age-Related Macular Degeneration (AMD); Macular Degeneration; Exudative Age-related Macular Degeneration; AMD; Macular Degeneration, Age-related, 10; Eye Diseases; Retinal Degeneration; Retinal Diseases

  1. Segmentation: Identification of consumer segments

    DEFF Research Database (Denmark)

    Høg, Esben

    2005-01-01

    It is very common to categorise people, especially in the advertising business. Also traditional marketing theory has taken in consumer segments as a favorite topic. Segmentation is closely related to the broader concept of classification. From a historical point of view, classification has its...... and analysed possible segments in the market. Results show that the statistical model used identified two segments - a segment of so-called "fish lovers" and another segment called "traditionalists". The "fish lovers" are very fond of eating fish and they actually prefer fish to other dishes...... origin in other sciences as for example biology, anthropology etc. From an economic point of view, it is called segmentation when specific scientific techniques are used to classify consumers to different characteristic groupings. What is the purpose of segmentation? For example, to be able to obtain...

  2. On Degenerate Partial Differential Equations

    OpenAIRE

    Chen, Gui-Qiang G.

    2010-01-01

    Some of recent developments, including recent results, ideas, techniques, and approaches, in the study of degenerate partial differential equations are surveyed and analyzed. Several examples of nonlinear degenerate, even mixed, partial differential equations, are presented, which arise naturally in some longstanding, fundamental problems in fluid mechanics and differential geometry. The solution to these fundamental problems greatly requires a deep understanding of nonlinear degenerate parti...

  3. 经前路椎体次全切钛笼置入锁定钢板螺丝钉内固定治疗相邻两节段脊髓型颈椎病%Adjacent Two Segments Anterior Subtotal Titanium Cage into the ;Locking Plate Screw Fixation for the Treatment of Cervical Spondylotic Myelopathy

    Institute of Scientific and Technical Information of China (English)

    青祖宏; 刘明; 高巍; 何蔚; 刘杨; 李永焕

    2013-01-01

    Objective To summarize the clinical efficacy of the anterior corpectomy cut with titanium cage and locking plate screw fixation for the treatment of two adjacent cervical spondylotic myelopathy.Method August 2010~December 2012,Anterior corpectomy cut with titanium cage and locking plate screw fixation for the treatment of adjacent two segments cervical spondylotic myelopathy 25 cases,including 18 men and 7 women patients,aged 33~75 years,mean 56.5 years.In 25 patients with varying degrees of symptoms of spinal cord compression. There are 9 cases(C4/C5). There are 15 cases(C5/C6).There are 1 case(C6/C7).Observed lateral cervical spine,cervical hyperextension flexion X-rays and cervical MR, before and after surg ery and follow-up phase,so as to learn spinal cord compression,cervical stability and postoperative cervical height,curvature,titanium cage plate screw position and cervical fusion. Compared preoperative to postoperative and follow-up,pain visual analog scale (VAS) and the Japan Orthopaedics Association (JOA) pain score.Results Operative time (120±30) min,blood loss (150±50)ml.The surgery does not appear related complications.The followed up time are 2~24 months (mean 12.5 months). Nerve function significantly improved.JOA score increased from preoperative 6.2±1.1 to the last follow-up 14.3±1.5,with an average improvement rate was (82.3±11.4)%.VAS average score is 2.1 points.The follow-up period is not found that the titanium cage shift,loose screws and lesion spinal cord compression phenomenon.Conclusion Anterior corpectomy cut with titanium cage and locking plate screw fixation for the treatment of two adjacent segments of cervical spondylotic myelopathy,effectively relieve nerve compression of the spinal cord,quickly restored cervical curvature and height,reconstruction of spinal stability,shorter operative time,less bleeding, and less damage.It has created favorable conditions for the rehabilitation of neurological function in patients,which is an

  4. K-Rod 动态稳定系统与 Dynesys 非融合系统在多节段腰椎退变中的近期疗效比较%Comparison of short-term clinical effect of K - Rod pedicle dynamic fixation system and Dynesys system for multiple segmental lumbar degeneration

    Institute of Scientific and Technical Information of China (English)

    谢雁春; 刘军; 于海龙; 陈语

    2015-01-01

    Objective To compare the short-term clinical effect of K-Rod pedicle dynamic fixation system and Dynesys system for multiple segmental lumbar degeneration. Methods From January 2010 to October 2012,60 patients with multiple segmental lumbar degeneration who were accepted K -Rod pedicle dynamic fixation system and Dynesys system were retrospectively reviewed.The 60 patients were divided into K - Rod group and fusion group,30 cases of patients with K - Rod pedicle dynamic fixation system who were accepted responsibility segmental decompression intervertebral fusion and internal fixation,degenerative segmental unfusion internal fixation.30 cases with Dynesys system who were accepted posterior decompression,discectomy and Dynesys unfusion internal fixation.Clinical assessments were based on comparion of Oswestry disability index score,visual analogous scale (VAS),postoperative lumbar hyperextension,hyperbend X-ray film lumbar ROM value (lumbar flexion mobility),average operation time, intraoperative blood loss,the average length of stay of two groups. Results All of 60 cases were achieved 12 to 24 months follow-up,compared to preoperative,the difference of Oswestry disability index score and visual analogous scale (VAS) for two groups were statistically significant,but the difference of Oswestry disability index score and visual analogous scale (VAS),average operation time,blood loss, the average length of stay(ALOS) between two groups were unstatistically significant. Conclusion In the treatment of multiple segmental lumbar degeneration,both K - Rod pedicle dynamic fixation system and Dynesys system can obtain satisfactory short-term clinical effect and have advantages of less intraoperative blood loss,shorter operation time,postoperative small effects on lumbar spine mobility.%目的:探讨比较 K-Rod 椎弓根动态稳定系统与 Dynesys 非融合系统在多节段腰椎退变的近期临床疗效。方法选择2010年1月至2012年10月于沈阳军

  5. 经皮椎间孔镜下TESSYS技术修复腰椎固定融合后邻近节段退行性变%Degenerative changes in adjacent segments after lumbar fixation and fusion:transforaminal endoscopic spine system

    Institute of Scientific and Technical Information of China (English)

    李建江; 楚戈; 杨涛; 黄异飞; 吴彦生; 刘岩路

    2015-01-01

    背景:椎间孔镜脊柱微创技术是目前治疗腰椎间盘突出症创伤最小的方法,可在局麻下进行,它不需要切除小关节,也不会破坏椎板,对脊柱的稳定性破坏最小。目的:探讨经皮椎间孔镜下TESSYS技术治疗腰椎固定融合术后邻近节段退行性改变引发腰腿痛的短期疗效。方法:纳入后路腰椎植骨融合内固定术后出现退行性改变发展到需二次手术的患者31例,其中男23例,女8例,年龄45-81岁,术后时间为1.1-5.7年,L3-4单节段3例,L4-5单节段15例,L5S1单节段8例,多节段5例。均选择经皮椎间孔镜下 TESSYS 技术治疗,治疗随访6个月,观察目测类比评分及腰椎功能日本骨科协会JOA评分变化。结果与结论:患者术中即感觉腰腿疼痛症状明显缓解,术后即可下地行走活动,术后恢复比较满意,治疗后即刻、治疗后1,3,6个月的目测类比评分均低于治疗前,治疗后即刻、治疗后1,3,6个月的腰椎功能日本骨科协会JOA评分均高于治疗前。表明经皮椎间孔镜下TESSYS 技术治疗后路腰椎植骨融合内固定术后退行性改变具有安全性高、手术时间短、出血少、并发症少、恢复快及患者易接受等优点。%BACKGROUND:Spine minimaly invasive technique through foraminal mirror is the method to treat lumbar disc herniation with minimal wound. This technique can be conducted under local anesthesia, and does not need to resect the smal joint or destroy the vertebral plate, and has smal damage to the spine. OBJECTIVE: To explore the short-period effects of transforaminal endoscopic spine system for adjacent-segment degenerative changes-caused low back pain after lumbar fixation and fusion. METHODS:A total of 31 patients with degenerative changes after posterior lumbar bone graft fusion fixation, who required secondary surgery, were enroled in this study, including 23 males and 8 females, at the age of 45

  6. Laenderyggens degeneration og radiologi

    DEFF Research Database (Denmark)

    Jacobsen, Steffen; Gosvig, Kasper Kjaerulf; Sonne-Holm, Stig

    2006-01-01

    Low back pain (LBP) is one of the most common conditions, and at the same time one of the most complex nosological entities. The lifetime prevalence is approximately 80%, and radiological features of lumbar degeneration are almost universal in adults. The individual risk factors for LBP and signi......Low back pain (LBP) is one of the most common conditions, and at the same time one of the most complex nosological entities. The lifetime prevalence is approximately 80%, and radiological features of lumbar degeneration are almost universal in adults. The individual risk factors for LBP...... and significant relationships between radiological findings and subjective symptoms have both been notoriously difficult to identify. The lack of consensus on clinical criteria and radiological definitions has hampered the undertaking of properly executed epidemiological studies. The natural history of LBP...

  7. Quantum degenerate systems

    Energy Technology Data Exchange (ETDEWEB)

    Micheli, Fiorenza de [Centro de Estudios Cientificos, Arturo Prat 514, Valdivia (Chile); Instituto de Fisica, Pontificia Universidad Catolica de Valparaiso, Casilla 4059, Valparaiso (Chile); Zanelli, Jorge [Centro de Estudios Cientificos, Arturo Prat 514, Valdivia (Chile); Universidad Andres Bello, Av. Republica 440, Santiago (Chile)

    2012-10-15

    A degenerate dynamical system is characterized by a symplectic structure whose rank is not constant throughout phase space. Its phase space is divided into causally disconnected, nonoverlapping regions in each of which the rank of the symplectic matrix is constant, and there are no classical orbits connecting two different regions. Here the question of whether this classical disconnectedness survives quantization is addressed. Our conclusion is that in irreducible degenerate systems-in which the degeneracy cannot be eliminated by redefining variables in the action-the disconnectedness is maintained in the quantum theory: there is no quantum tunnelling across degeneracy surfaces. This shows that the degeneracy surfaces are boundaries separating distinct physical systems, not only classically, but in the quantum realm as well. The relevance of this feature for gravitation and Chern-Simons theories in higher dimensions cannot be overstated.

  8. Cataracts and macular degeneration.

    Science.gov (United States)

    Shoch, D

    1979-09-01

    The intraocular lens restores general vision and some degree of independence and mobility to patients with dense cataracts and macular degeneration. The patient, however, must be repeatedly warned that fine central vision, particularly reading, will not be possible after the surgery. An aphakic spectacle leaves such patients a narrow band of vision when superimposed over the macular lesion, and contact lenses are too small for the patient to manage insertion without help.

  9. Investigation of retinal microstructure in healthy eyes and dry age-related macular degeneration using a combined AO-OCT-SLO system

    Science.gov (United States)

    Wells-Gray, Elaine M.; Choi, Stacey S.; Ohr, Matthew; Cebulla, Colleen M.; Doble, Nathan

    2017-02-01

    Combined adaptive optics (AO) optical coherence tomography (OCT) scanning laser ophthalmoscopy (SLO) imaging allows simultaneous en face and cross sectional views of the retina. We describe improvements to our AO-OCT-SLO system and highlight its resolution capability and clinical utility by presenting results from 3 control and 4 dry agerelated macular degeneration (AMD) subjects. From a group of subjects with healthy eyes, OCT A-scans were grouped as originating from cones or rods and were averaged. The resulting reflectance profiles were then used to identify the location of cone and rod segments. Results for rods and cones were compared, with the focus on inner segment (IS) and outer segment (OS) structures and where these cells embed into the retinal pigment epithelium (RPE). In the AMD patients, cone IS and OS lengths were measured over and around drusen for two retinal regions (fovea-2° and 2°-4°), and those results were correlated to drusen height. For the fovea-2° region, the drusen height that caused statistically significant shortening of cone ISL and OSL compared to the unaffected adjacent area were 40 μm and 50 μm respectively (p = 0.009, and p region, the equivalent drusen heights that caused significant shortening of segment length were 60 μm for IS (p = 0.017) and 80 μm for OS (p < 0.001)

  10. ETHIOPIAN RIFT AND ADJACENT HIGHLANDS

    African Journals Online (AJOL)

    of the kinetic temperature of the central Ethiopian rift lakes and adjacent highlands. ... component of the surface radiation balance from only one surface measurement derived from NOAA. TM and ... The basin studied is part of the Ethiopian Rift system bounded within the limits .... Topographic conditions, which determine ...

  11. Geometric phases for non-degenerate and degenerate mixed states

    CERN Document Server

    Singh, K; Basu, K; Chen, J L; Du Jiang Feng

    2003-01-01

    This paper focuses on the geometric phase of general mixed states under unitary evolution. Here we analyze both non-degenerate as well as degenerate states. Starting with the non-degenerate case, we show that the usual procedure of subtracting the dynamical phase from the total phase to yield the geometric phase for pure states, does not hold for mixed states. To this end, we furnish an expression for the geometric phase that is gauge invariant. The parallelity conditions are shown to be easily derivable from this expression. We also extend our formalism to states that exhibit degeneracies. Here with the holonomy taking on a non-abelian character, we provide an expression for the geometric phase that is manifestly gauge invariant. As in the case of the non-degenerate case, the form also displays the parallelity conditions clearly. Finally, we furnish explicit examples of the geometric phases for both the non-degenerate as well as degenerate mixed states.

  12. Vibration damping for the Segmented Mirror Telescope

    Science.gov (United States)

    Maly, Joseph R.; Yingling, Adam J.; Griffin, Steven F.; Agrawal, Brij N.; Cobb, Richard G.; Chambers, Trevor S.

    2012-09-01

    The Segmented Mirror Telescope (SMT) at the Naval Postgraduate School (NPS) in Monterey is a next-generation deployable telescope, featuring a 3-meter 6-segment primary mirror and advanced wavefront sensing and correction capabilities. In its stowed configuration, the SMT primary mirror segments collapse into a small volume; once on location, these segments open to the full 3-meter diameter. The segments must be very accurately aligned after deployment and the segment surfaces are actively controlled using numerous small, embedded actuators. The SMT employs a passive damping system to complement the actuators and mitigate the effects of low-frequency (operating deflection shapes of the mirror and to quantify segment edge displacements; relative alignment of λ/4 or better was desired. The TMDs attenuated the vibration amplitudes by 80% and reduced adjacent segment phase mismatches to acceptable levels.

  13. Lack of effect of microfilament or microtubule cytoskeleton-disrupting agents on restriction of externalized phosphatidylserine to rod photoreceptor outer segment tips.

    Science.gov (United States)

    Ruggiero, Linda; Finnemann, Silvia C

    2014-01-01

    In the mammalian retina, life-long renewal of rod photoreceptor outer segments involves circadian shedding of distal outer segment tips and their prompt phagocytosis by the adjacent retinal pigment epithelium (RPE) every morning after light onset. Failure of this process causes retinal dystrophy in animal models and its decline likely contributes to retinal aging and some forms of degeneration of the human retina. We previously found that surface exposure of the membrane phospholipid phosphatidylserine (PS) is restricted to outer segment tips with discrete boundaries in mouse retina and that both frequency and length of tips exposing PS peak after light onset. Here, we sought to test mechanisms photoreceptors use to restrict PS specifically to their outer segment tips. To this end, we tested whether nocodazole or cytochalasin D, perturbing microtubule or F-actin microfilament cytoskeleton, respectively, affect localization of externalized PS at outer segment tips. Fluorescence imaging of PS exposed by rods in freshly dissected, live mouse retina showed normal PS demarcation of outer segment tips regardless of drug treatment. These results suggest that the mechanism that restricts externalized PS to rod tips is independent of F-actin and microtubule cytoskeletal systems.

  14. 颈椎单节段融合术后相邻各节段运动补偿的规律研究%Research of the motion compensation after single segmental cervical spine fusion surgery

    Institute of Scientific and Technical Information of China (English)

    张睿; 周文钰; 顾洪生; 刘伟强; 白波; 王大平

    2014-01-01

    目的 了解颈椎单节段融合术后上、下相邻及非相邻节段的运动补偿规律.方法 通过三维运动采集系统,捕捉到6具新鲜人尸体颈椎单节段融合术前后C2~T1各节段的运动角度数据.结果 经过归一化处理后,分析得出颈椎单节段融合术后各节段的运动变化规律,发现融合术后其他各节段运动幅度均有不同程度的增加,尤其是下相邻节段,差异有统计学意义(P<0.05).结论 颈椎单节段融合术后邻近节段的代偿性运动幅度增加是导致其退变的重要原因.%Objective To know the motion compensation regulation of each segments after single segmental cervical spine fusion surgery.Methods With the help of 3D motion information collecting system,the movement angle of each segment was recorded before and after single segmental cervical spine fusion surgery.Results All the statistics are dealed with normalization,we got the statistics of the motion compensation regulation of each segments after single segmental cervical spine fusion surgery,range of motion of each segment increased diversely,especially the lower adjacent segment,with statistical significance(P<0.05).Conclusion Compensatory enhancement of the range of motion of adjacent segments is one of the important reasons lead to the degeneration.

  15. MRI水成像序列在眼运动神经麻痹病因诊断中的应用%The value of 3D-CISS sequence in displaying the cisternal segment of the ophthalmic motion nerves and its abnormal adjacent relationships

    Institute of Scientific and Technical Information of China (English)

    江万里; 梁长虎; 乌大尉; 柳澄

    2013-01-01

    目的 应用3D-CISS(3-D Constructive Interference in Steady State)序列对脑池段眼运动神经的异常毗邻组织结构进行显示与研究,为临床诊断及手术获得详尽的MR影像资料.方法 对23名眼运动障碍患者进行3D-CISS序列MR成像,应用MPR技术在最佳方位层面观察眼运动神经与其异常毗邻组织的压迫关系.结果 23例单侧眼运动障碍患者的3D-CISS序列MR成像均显示相应眼运动神经明显受压变形:动眼神经受压11例,其中大脑后动脉(PCA)血管压迫5例,小脑上动脉(SCA)压迫1例,基底动脉(BA)压迫2例,肿瘤压迫3例;展神经受压10例,其中基底动脉(BA)血管压迫4例,小脑前下动脉(AICA)压迫2例,肿瘤压迫4例;滑车神经受压2例,均为小脑上动脉(SCA)分支血管压迫.结论 3D-CISS序列结合MPR技术能够准确显示眼运动神经的毗邻关系,具有重要的临床意义.%Objective To obtain the detailed anatomical data of image for clinic through the application of 3D-CISS sequence in displaying the cisternal segment of the ophthalmic motion nerves and its abnormal adjacent relationships. Methods 23 patients with palsy of the ophthalmic motion nerves underwent 3D-CISS MR imaging, the syntopy of the ophthalmic motion nerves to its related pathological changes were observed from the different angles on multi-planar reconstruction (MPR) images. Results 23 patients with palsy of the unilateral ophthalmic motion nerves were all displayed with the corresponding apparent distortion caused by press: 11 oculomotor nerves were pressed, among them 5, were pressed by PCA, 1 by SCA, 2 by BA, 3 by tumor in the pontine cistern; 10 abducent nerves were pressed, among them 4 were pressed by BA, 2 by AICA and 4 by tumor in the pontine cistern; 2 trochlear nerves were all pressed by the branch of SCA. Conclusion 3D-CISS sequence and MPR technique are the optimal imaging methods for the display of the syntopy of the ophthalmic motion nerve to its related

  16. Fingerprint Segmentation

    OpenAIRE

    Jomaa, Diala

    2009-01-01

    In this thesis, a new algorithm has been proposed to segment the foreground of the fingerprint from the image under consideration. The algorithm uses three features, mean, variance and coherence. Based on these features, a rule system is built to help the algorithm to efficiently segment the image. In addition, the proposed algorithm combine split and merge with modified Otsu. Both enhancements techniques such as Gaussian filter and histogram equalization are applied to enhance and improve th...

  17. Intervertebral disc degeneration in dogs

    NARCIS (Netherlands)

    Bergknut, Niklas

    2011-01-01

    Back pain is common in both dogs and humans, and is often associated with intervertebral disc (IVD) degeneration. The IVDs are essential structures of the spine and degeneration can ultimately result in diseases such as IVD herniation or spinal instability. In order to design new treatments halting

  18. Double Degenerate Stars

    Institute of Scientific and Technical Information of China (English)

    LUO Xin-Lian; BAI Hua; ZHAO Lei

    2008-01-01

    Regardless of the formation mechanism, an exotic object, the double degenerate star (DDS), is introduced and investigated, which is composed of baryonic matter and some unknown fermion dark matter. Different from the simple white dwarfs (WDs), there is additional gravitational force provided by the unknown fermion component inside DDSs, which may strongly affect the structure and the stability of such kind of objects. Many possible and strange observational phenomena connecting with them are concisely discussed. Similar to the normal WD, this object can also experience thermonuclear explosion as type Ia supernova explosion when DDS's mass exceeds the maximum mass that can be supported by electron degeneracy pressure. However, since the total mass of baryonic matter can be much lower than that of WD at Chandrasekhar mass limit, the peak luminosity should be much dimmer than what we expect before, which may throw a slight shadow on the standard candle of SN Ia in the research of cosmology.

  19. Adjacency-preserving spatial treemaps

    Directory of Open Access Journals (Sweden)

    Kevin Buchin

    2016-03-01

    Full Text Available Rectangular layouts, subdivisions of an outer rectangle into smaller rectangles, have many applications in visualizing spatial information, for instance in rectangular cartograms in which the rectangles represent geographic or political regions. A spatial treemap is a rectangular layout with a hierarchical structure: the outer rectangle is subdivided into rectangles that are in turn subdivided into smaller rectangles. We describe algorithms for transforming a rectangular layout that does not have this hierarchical structure, together with a clustering of the rectangles of the layout, into a spatial treemap that respects the clustering and also respects to the extent possible the adjacencies of the input layout.

  20. Facts about Age-Related Macular Degeneration

    Science.gov (United States)

    ... Degeneration (AMD) > Facts About Age-Related Macular Degeneration Facts About Age-Related Macular Degeneration This information was ... an Eye Care Professional Last Reviewed: September 2015 Fact Sheet Blurb The National Eye Institute (NEI) is ...

  1. Conjunctival intraepithelial neoplasia with corneal furrow degeneration

    Directory of Open Access Journals (Sweden)

    Pukhraj Rishi

    2014-01-01

    Full Text Available A 68-year-old man presented with redness of left eye since six months. Examination revealed bilateral corneal furrow degeneration. Left eye lesion was suggestive of conjunctival squamous cell carcinoma, encroaching on to cornea. Anterior segment optical coherence tomography (AS-OCT confirmed peripheral corneal thinning. Fluorescein angiography confirmed intrinsic vascularity of lesion. Patient was managed with "no touch" surgical excision, dry keratectomy without alcohol, cryotherapy, and primary closure. Pathologic examination of removed tissue confirmed clinical diagnosis. Management of this particular case required modification of standard treatment protocol. Unlike the alcohol-assisted technique of tumor dissection described, ethyl alcohol was not used for risk of corneal perforation due to underlying peripheral corneal thinning. Likewise, topical steroids were withheld in the post-operative period. Three weeks post-operatively, left eye was healing well. Hence, per-operative usage of absolute alcohol and post-operative use of topical steroids may be best avoided in such eyes.

  2. [CORRELATION OF LUMBAR FACET JOINT DEGENERATION AND SPINE-PELVIC SAGITTAL BALANCE].

    Science.gov (United States)

    Lo, Xin; Zhang, Bin; Liu, Yuan; Dai, Min

    2015-08-01

    To investigate the relationship between lumbar facet joint degeneration of each segment and spine-pelvic sagittal balance parameters. A retrospective analysis was made the clinical data of 120 patients with lumbar degenerative disease, who accorded with the inclusion criteria between June and November 2014. There were 58 males and 62 females with an average age of 53 years (range, 24-77 years). The disease duration ranged from 3 to 96 months (mean, 6.6 months). Affected segments included L3,4 in 32 cases, L4,5 in 47 cases, and L5, S1 in 52 cases. The CT and X-ray films of the lumbar vertebrae were taken. The facet joint degeneration was graded based on the grading system of Pathria. The spine-pelvic sagittal balance parameters were measured, including lumbar lordosis (LL), upper lumbar lordosis (ULL), lower lumbar lordosis (LLL), pelvic incidence (PI), pelvic tilt (PT), and sacral slope (SS). According to normal range of PI, the patients were divided into 3 groups: group A (PI was less than normal range), group B (PI was within normal range), and group C (PI was more than normal range). The facet joint degeneration was compared; according to the facet joint degeneration degree, the patients were divided into group N (mild degeneration group) and group M (serious degeneration group) to observe the relationship of lumbar facet joint degeneration of each segment and spine-pelvic sagittal balance parameters. At L4,5 and L5, S1, facet joint degeneration showed significant difference among groups A, B, and C (P 0.05). There was no significant difference in the other spine-pelvic sagittal balance parameters between groups N and M at each segment (P > 0.05) except for PT (P spine.

  3. [Age related macular degeneration].

    Science.gov (United States)

    Sayen, Alexandra; Hubert, Isabelle; Berrod, Jean-Paul

    2011-02-01

    Age-related macular degeneration (ARMD) is a multifactorial disease caused by a combination of genetic and environmental factors. It is the first cause of blindness in patients over 50 in the western world. The disease has been traditionally classified into early and late stages with dry (atrophic) and wet (neovascular) forms: neovascular form is characterized by new blood vessels development under the macula (choroidal neovascularisation) which lead to a rapid decline of vision associated with metamorphopsia and requiring an urgent ophtalmological examination. Optical coherence tomography is now one of the most important part of the examination for diagnosis and treatment. Patient with age related maculopathy should consider taking a dietary supplement such that used in AREDS. The treatment of the wet ARMD has largely beneficied since year 2006 of anti-VEGF (vascular endothelial growth factor) molecules such as ranibizumab or bevacizumab given as repeated intravitreal injections. A systematic follow up each 4 to 8 week in required for several years. There is no effective treatment at the moment for dry AMD. For patients with binocular visual acuity under 60/200 rehabilitation includes low vision specialist, vision aids and psychological support.

  4. SIR2005-5073_CBRWM_LandSegments

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data set is an ArcGIS shapefile depicting land segments in the Chesapeake Bay Watershed and adjacent states of New York, Pennsylvania, Maryland, West Virginia,...

  5. Degenerate pseudo-Riemannian metrics

    CERN Document Server

    Hervik, Sigbjorn; Yamamoto, Kei

    2014-01-01

    In this paper we study pseudo-Riemannian spaces with a degenerate curvature structure i.e. there exists a continuous family of metrics having identical polynomial curvature invariants. We approach this problem by utilising an idea coming from invariant theory. This involves the existence of a boost, the existence of this boost is assumed to extend to a neighbourhood. This approach proves to be very fruitful: It produces a class of metrics containing all known examples of degenerate metrics. To date, only Kundt and Walker metrics have been given, however, our study gives a plethora of examples showing that degenerate metrics extend beyond the Kundt and Walker examples. The approach also gives a useful criterion for a metric to be degenerate. Specifically, we use this to study the subclass of VSI and CSI metrics (i.e., spaces where polynomial curvature invariants are all vanishing or constants, respectively).

  6. Age-Related Macular Degeneration

    Science.gov (United States)

    ... version of this page please turn Javascript on. Age-related Macular Degeneration About AMD Click for more ... a leading cause of vision loss among people age 60 and older. It causes damage to the ...

  7. On the degenerate phase boundaries

    CERN Document Server

    Ma, Y; Kuang, Z; Ma, Yongge; Liang, Canbin; Kuang, Zhiquan

    1999-01-01

    The structure of the phase boundary between degenerate and non-degenerate regions in Ashtekar's gravity has been studied by Bengtsson and Jacobson who conjectured that the "phase boundary" should always be null. In this paper, we reformulate the reparametrization procedure in the mapping language and distinguish a phase boundary from its image. It is shown that the image has to be null, while the nullness of the phase boundary requries more suitable criterion.

  8. Effect of Static Load on the Nucleus Pulposus of Rabbit Intervertebral Disc Motion Segment in Ex vivo Organ Culture

    Institute of Scientific and Technical Information of China (English)

    Li-Guo Zhu; Min-Shan Feng; Jia-Wen Zhan; Ping Zhang; Jie Yu

    2016-01-01

    Background:The development of mechanically active culture systems helps increase the understanding of the role of mechanical stress in intervertebral disc (IVD) degeneration.Motion segment cultures allow for preservation of the native IVD structure,and adjacent vertebral bodies facilitate the application and control of mechanical loads.The purpose of this study was to establish loading and organ culture methods for rabbit IVD motion segments to study the effect of static load on the whole disc organ.Methods:IVD motion segments were harvested from rabbit lumbar spines and cultured in no-loading 6-well plates (control conditions) or custom-made apparatuses under a constant,compressive load (3 kg,0.5 MPa) for up to 14 days.Tissue integrity,matrix synthesis,and the matrix gene expression profile were assessed after 3,7,and 14 days of culturing and compared with those of fresh tissues.Results:The results showed that ex vivo culturing of motion segments preserved tissue integrity under no-loading conditions for 14 days whereas the static load gradually destroyed the morphology after 3 days.Proteoglycan contents were decreased under both conditions,with a more obvious decrease under static load,and proteoglycan gene expression was also downregulated.However,under static load,immunohistochemical staining intensity and collagen Type Ⅱ alpha 1 (COL2A 1) gene expression were significantly enhanced (61.54 ± 5.91,P =0.035) and upregulated (1.195 ± 0.040,P =0.000),respectively,compared with those in the controls (P < 0.05).In contrast,under constant compression,these trends were reversed.Our initial results indicated that short-term static load stimulated the synthesis of collagen Type Ⅱ alpha l;however,sustained constant compression led to progressive degeneration and specifically to a decreased proteoglycan content.Conclusions:A loading and organ culture system for ex vivo rabbit IVD motion segments was developed.Using this system,we were able to study the effects of

  9. [Segmental neurofibromatosis].

    Science.gov (United States)

    Zulaica, A; Peteiro, C; Pereiro, M; Pereiro Ferreiros, M; Quintas, C; Toribio, J

    1989-01-01

    Four cases of segmental neurofibromatosis (SNF) are reported. It is a rare entity considered to be a localized variant of neurofibromatosis (NF)-Riccardi's type V. Two cases are male and two female. The lesions are located to the head in a patient and the other three cases in the trunk. No family history nor transmission to progeny were manifested. The rest of the organs are undamaged.

  10. Wilson's disease (hepatolenticular degeneration).

    Science.gov (United States)

    Herron, B E

    1976-01-01

    Wilson's disease, or hepatolenticular degeneration, is a rare inherited disorder of copper metabolism which usually affects young people. Excess copper accumulates in the tissues, primarily in the liver, brain, and cornea. This copper deposition results in a wide range of hepatic and neurological symptoms, and may produce psychiatric illness. Hepatic involvement often occurs in childhood, while neurological deficits generally are detected at a later age. The disease is inherited in an autosomal recessive fashion. Ocular findings are of particular importance because the corneal copper deposition, forming the Kayser-Fleischer ring,is the only pathognomonic sign of the disease. The structure of the ring and the presence of copper have been well established. An anterior capsular deposition of copper in the lens results in a characteristic sunflower cataract in some of these patients. Other ocular abnormalities have been described but are much less common. The pathogenesis of the disease and the basic genetic defect remain obscure. It is clear that there is excess copper in the tissues, but the mechanism of its deposition is unknown. It is in some way associated with a failure to synthesize the serum copper protein ceruloplasmin normally. Another theory suggests that an abnormal protein with a high affinity for copper may bind the metal in the tissues. The diagnosis may be suggested by the clinical manifestations and confirmed by the presence of a Kayser-Fleischer ring. In the absence of these findings biochemical determinations are necessary. The most important of these are the serum ceruloplasmin, the urinary copper, and the hepatic copper concentration on biopsy. Treatment consists in the administration of the copper chelating agent, penicillamine, and the avoidance of a high copper intake. This usually results in marked clinical improvement if irreversible tissue damage has not occurred. Maintenance therapy for life is necessary in order to continue the negative

  11. Einstein Universe under Deconstruction: the case with degenerate fermions

    CERN Document Server

    Kan, Nahomi; Shiraishi, Kiyoshi

    2011-01-01

    We study self-consistent static solutions for an Einstein universe in a graph-based induced gravity. In the generalization of the deconstruction model based on the graph, the eigenvalues of the graph Laplacian and the adjacent matrix gives the mass spectrum the particles. Thus we can easily control UV divergences at one-loop level in such a model. We use the calculation method with the spectrum distribution function of the graph and search for the static solution supported by the degenerate pressure of the fermion (at zero temperature). The report is based on arXiv:1110.5697.

  12. The relationship between disc degeneration and flexibility of the lumbar spine

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, Nobuhiro; Fujimoto, Yoshinori; Ochi, Mitsuo [Hiroshima Univ. (Japan). Graduate School of Biomedical Sciences; An, H.S.; Lim, T.H.; Fujiwara, Atsushi [Rush-Presbyterian-St. Luke' s Medical Center, Chicago, IL (United States)

    2003-04-01

    The purpose of this study was to investigate the relationship between grade of degeneration of intervertebral discs and 3-dimensional biomechanical characteristics of the motion segment under multidirectional loading conditions. The material used in this study consisted of 114 lumbar motion segments from T12-L1 to L5-S1 retrieved from 47 fresh cadaver spines (average age at death, 68 years; range, 39 to 87 years). The severity of degeneration (grades I to V according to Thomson's system) was determined by examining magnetic resonance (MR) images and cryomicrotome sections. Pure unconstrained moments with dead weights were applied to the motion segments in 6 load steps. The directions of loading included flexion, extension, right and left axial rotation, and right and left lateral bending. Segments from the upper lumbar levels (T12-L1 to L3-4) tended to have greater rotational movement in flexion, extension, and axial rotation with disc degeneration up to grade IV, but the motion decreased when the disc degeneration reached grade V. In the lower lumbar spine, motion in axial rotation and lateral bending at L4-5 and L5-S1 was increased in grade III. These results suggest that kinematic properties of the lumbar spine are related to disc degeneration. Disc degeneration, particularly in grades III and IV, in which radial tears of the anulus fibrosus are found, was generally associated with greater motion. Disc space collapse and osteophyte formation, as found in grade V, resulted in stabilization of the motion segments. (author)

  13. Compressed Adjacency Matrices: Untangling Gene Regulatory Networks.

    Science.gov (United States)

    Dinkla, K; Westenberg, M A; van Wijk, J J

    2012-12-01

    We present a novel technique-Compressed Adjacency Matrices-for visualizing gene regulatory networks. These directed networks have strong structural characteristics: out-degrees with a scale-free distribution, in-degrees bound by a low maximum, and few and small cycles. Standard visualization techniques, such as node-link diagrams and adjacency matrices, are impeded by these network characteristics. The scale-free distribution of out-degrees causes a high number of intersecting edges in node-link diagrams. Adjacency matrices become space-inefficient due to the low in-degrees and the resulting sparse network. Compressed adjacency matrices, however, exploit these structural characteristics. By cutting open and rearranging an adjacency matrix, we achieve a compact and neatly-arranged visualization. Compressed adjacency matrices allow for easy detection of subnetworks with a specific structure, so-called motifs, which provide important knowledge about gene regulatory networks to domain experts. We summarize motifs commonly referred to in the literature, and relate them to network analysis tasks common to the visualization domain. We show that a user can easily find the important motifs in compressed adjacency matrices, and that this is hard in standard adjacency matrix and node-link diagrams. We also demonstrate that interaction techniques for standard adjacency matrices can be used for our compressed variant. These techniques include rearrangement clustering, highlighting, and filtering.

  14. Mixed segmentation

    DEFF Research Database (Denmark)

    Bonde, Anders; Aagaard, Morten; Hansen, Allan Grutt

    This book is about using recent developments in the fields of data analytics and data visualization to frame new ways of identifying target groups in media communication. Based on a mixed-methods approach, the authors combine psychophysiological monitoring (galvanic skin response) with textual...... content analysis and audience segmentation in a single-source perspective. The aim is to explain and understand target groups in relation to, on the one hand, emotional response to commercials or other forms of audio-visual communication and, on the other hand, living preferences and personality traits...

  15. Dynamical light control in longitudinally modulated segmented waveguide arrays

    CERN Document Server

    Kartashov, Yaroslav V

    2011-01-01

    We address light propagation in segmented waveguide arrays where the refractive index is longitudinally modulated with an out-of-phase modulation in adjacent waveguides, so that the coupling strength varies along propagation direction. Thus in resonant segments coupling may be inhibited hence light remains localized, while in detuned segments coupling results in complex switching scenarios that may be controlled by stacking several resonant and nonresonant segments. By tuning the modulation frequency and lengths of waveguide segments one may control the distribution of light among the output guides, including loca-lizing all light in the selected output channel.

  16. Segmented blockcopolymers with uniform amide segments

    NARCIS (Netherlands)

    Husken, D.; Krijgsman, J.; Gaymans, R.J.

    2004-01-01

    Segmented blockcopolymers based on poly(tetramethylene oxide) (PTMO) soft segments and uniform crystallisable tetra-amide segments (TxTxT) are made via polycondensation. The PTMO soft segments, with a molecular weight of 1000 g/mol, are extended with terephthalic groups to a molecular weight of 6000

  17. Genetics Home Reference: age-related macular degeneration

    Science.gov (United States)

    ... Resources (3 links) BrightFocus Foundation: Macular Degeneration Treatment Macular Degeneration Partnership: Low Vision Rehabilitation Prevent Blindness America: Age-Related Macular Degeneration (AMD) ...

  18. Clinical Impact of Sagittal Spinopelvic Parameters on Disc Degeneration in Young Adults.

    Science.gov (United States)

    Oh, Young-Min; Eun, Jong-Pil

    2015-10-01

    The sagittal balance plays an important role in the determination of shear and compressive forces applied on the anterior (vertebral bodies and intervertebral discs) and posterior (facet joints) elements of the lumbar vertebral column. Many studies have also examined the effect of structural changes in the disc on the biomechanical characteristics of the spinal segment. Nevertheless, the relationship between sagittal balance and the degree of disc degeneration has not been extensively explored. Thus, here we investigated the relationships between various sagittal spinopelvic parameters and the degree of disc degeneration in young adults.A total of 278 young adult male patients were included in this study (age range: 18-24 years old). Multiple sagittal spinopelvic parameters, including pelvic incidence (PI), sacral slope (SS), pelvic tilt (PT), lumbar lordosis (LL), sacral inclination (SI), lumbosacral angle (LSA), and sacral table angle (STA), were measured from standing lateral lumbosacral radiographs. The degree of intervertebral disc degeneration was classified using a modified Pfirrmann scale. To assess the pain intensity of each patient, the visual analogue scale (VAS) score for low back pain (LBP) was obtained from all the patients. Finally, the relationships between these spinopelvic parameters and the degree of disc degeneration in young adults were analyzed. Also, we performed multiple logistic regression study.Out of all the spinopelvic parameters measured in this study, a low STA and a low SI were the only significant risk factors that were associated with disc degeneration in young adults. It means that patients with disc degeneration tend to have more severe sacral kyphosis and vertical sacrum.We found that patients with disc degeneration showed a lower SI and lower STA compared with patients without disc degeneration in young adults. Therefore, we suggest that the patients with disc degeneration tend to have more vertical sacrum, more sacral kyphosis

  19. Gribov ambiguity and degenerate systems

    CERN Document Server

    Canfora, Fabrizio; Salgado-Rebolledo, Patricio; Zanelli, Jorge

    2014-01-01

    The relation between Gribov ambiguity and degeneracies in the symplectic structure of physical systems is analyzed. It is shown that, in finite-dimensional systems, the presence of Gribov ambiguities in regular constrained systems (those where the constraints are functionally independent) always leads to a degenerate symplectic structure upon Dirac reduction. The implications for the Gribov-Zwanziger approach to QCD are discussed.

  20. Pregnancy outcome of a patient following myomectomy performed during first trimester for red degeneration of fibroid

    Directory of Open Access Journals (Sweden)

    Asma Habib

    2016-08-01

    Full Text Available Pain due to red degeneration of fibroid during pregnancy is usually associated with large myomas. Necrobiosis / red degeneration typically manifests itself about midpregnancy when Lhe leiomyoma suddenly becomes acutely painful, enlarged and tender. The common differential diagnosis of this condition are torsion of the pedicle of an ovarian cyst/a leiomyoma, abruplion placentae, acute pyelitis or any abdominal catastrophe. Ultrasound can easily delineate the presence of myomas of mixed echogenicity along with pregnancy and clinical findings usually suggest the diagnosis of pregnancy complicated by red degeneration of fibroid. The acute pain usually subsides within 3-10 days of conservative treatment. Only refractory cases (2% of patients may demand surgical intervention in early gestation with the known risk of miscarriage. Here we report a pregnancy managed at 13 weeks by myomectomy for red degeneration. The patient ultimately delivered a healthy female child at 38 weeks by lower segment caesarean section.

  1. Imaging geographic atrophy in age-related macular degeneration.

    Science.gov (United States)

    Göbel, Arno P; Fleckenstein, Monika; Schmitz-Valckenberg, Steffen; Brinkmann, Christian K; Holz, Frank G

    2011-01-01

    Advances in retinal imaging technology have largely contributed to the understanding of the natural history, prognostic markers and disease mechanisms of geographic atrophy (GA) due to age-related macular degeneration. There is still no therapy available to halt or slow the disease process. In order to evaluate potential therapeutic effects in interventional trials, there is a need for precise quantification of the GA progression rate. Fundus autofluorescence imaging allows for accurate identification and segmentation of atrophic areas and currently represents the gold standard for evaluating progressive GA enlargement. By means of high-resolution spectral-domain optical coherence tomography, distinct microstructural alterations related to GA can be visualized.

  2. CERKL knockdown causes retinal degeneration in zebrafish.

    Directory of Open Access Journals (Sweden)

    Marina Riera

    Full Text Available The human CERKL gene is responsible for common and severe forms of retinal dystrophies. Despite intense in vitro studies at the molecular and cellular level and in vivo analyses of the retina of murine knockout models, CERKL function remains unknown. In this study, we aimed to approach the developmental and functional features of cerkl in Danio rerio within an Evo-Devo framework. We show that gene expression increases from early developmental stages until the formation of the retina in the optic cup. Unlike the high mRNA-CERKL isoform multiplicity shown in mammals, the moderate transcriptional complexity in fish facilitates phenotypic studies derived from gene silencing. Moreover, of relevance to pathogenicity, teleost CERKL shares the two main human protein isoforms. Morpholino injection has been used to generate a cerkl knockdown zebrafish model. The morphant phenotype results in abnormal eye development with lamination defects, failure to develop photoreceptor outer segments, increased apoptosis of retinal cells and small eyes. Our data support that zebrafish Cerkl does not interfere with proliferation and neural differentiation during early developmental stages but is relevant for survival and protection of the retinal tissue. Overall, we propose that this zebrafish model is a powerful tool to unveil CERKL contribution to human retinal degeneration.

  3. Prosodic cues enhance rule learning by changing speech segmentation mechanisms

    Directory of Open Access Journals (Sweden)

    Ruth eDe Diego-Balaguer

    2015-09-01

    Full Text Available Prosody has been claimed to have a critical role in the acquisition of grammatical information from speech. The exact mechanisms by which prosodic cues enhance learning are fully unknown. Rules from language often require the extraction of non-adjacent dependencies (e.g. he plays, he sings, he speaks. It has been proposed that pauses enhance learning because they allow computing non-adjacent relations helping word segmentation by removing the need to compute adjacent computations. So far only indirect evidence from behavioral and electrophysiological measures comparing learning effects after exposure to speech with and without pauses support this claim. By recording event-related potentials during the acquisition process of artificial languages with and without pauses between words with embedded non-adjacent rules we provide direct evidence on how the presence of pauses modifies the way speech is processed during learning to enhance segmentation and rule generalisation. The electrophysiological results indicate that pauses as short as 25 ms attenuated the N1 component irrespective of whether learning was possible or not. In addition, a P2 enhancement was present only when learning of non-adjacent dependencies was possible. The overall results support the claim that the simple presence of subtle pauses changed the segmentation mechanism used reflected in an exogenously driven N1 component attenuation and improving segmentation at the behavioral level. This effect can be dissociated from the endogenous P2 enhancement that is observed irrespective of the presence of pauses whenever non-adjacent dependencies are learned.

  4. Spheroidal Degeneration of the Cornea

    Directory of Open Access Journals (Sweden)

    Erdem Dinç

    2011-08-01

    Full Text Available A thirty-one-year-old male patient presented with bilateral epiphora and stinging sensation in the cornea. Detailed history revealed that a bilateral corneal scraping had been made regarding the initial diagnosis of fungal keratitis. His bestcorrected visual acuities were 20/20 and 20/30 in right and left eyes, respectively. Biomicroscopy showed bilateral amber colored spherules in the anterior stroma of the central cornea. The diagnosis of spheroidal corneal degeneration was established and symptomatic therapy with artificial tear drops was prescribed. Ultraviolet light is widely accepted to be the main etiological factor in the pathogenesis of spheroidal degeneration. Because of difficulties in the early stages of the diagnostic process of the disease, incorrect diagnoses can be made with inappropriate interventions. (Turk J Ophthalmol 2011; 41: 264-6

  5. Morphologic features of spontaneous annular tears and disc degeneration in the aging sand rat (Psammomys obesus obesus).

    Science.gov (United States)

    Gruber, H E; Hanley, E N

    2017-08-11

    The sand rat, a member of the gerbil family, is a valuable small animal model in which intervertebral disc degeneration occurs spontaneously as the animal ages. Radiographic features of cervical and lumbar degeneration resemble those in human spines. We conducted a retrospective analysis of spines of 140 animals 3-41 months old focusing specifically on the presence of annular tears that are not visible by radiography and have not been described previously in the sand rat disc. During degeneration of the nucleus pulposus, notochordal cell death occurs and granular material, which stains with Alcian blue for proteoglycans, accumulates. Lamellar architecture also deteriorates and annular tears occur that are morphologically similar to the concentric, radiating and transdiscal annular tears in human discs. These tears contain granular material that provides a "marker" that can be used to distinguish the annular tears from artefactual separations during sectioning. We observed lamellar degeneration and separation in the annulus fibrosus at 4 months with associated tears that contained granular material in the nucleus. Tears that contained granular material and displacement of the degenerating nucleus were common in cervical and lumbar discs of animals older than 9 months; some specimens showed tears at 4 and 5 months. With advanced degeneration, granular globules were displaced dorsally adjacent to and into the spinal cord area and also ventrally into regions where osteophytes formed. We present morphologic data that expand the utility of this rodent model of spontaneous age-related disc degeneration and provide novel information on annular tears and disc degeneration.

  6. An Efficient Character Segmentation Based on VNP Algorithm

    Directory of Open Access Journals (Sweden)

    S. Chitrakala

    2012-12-01

    Full Text Available Character segmentation is an important preprocessing stage in image processing applications such as OCR, License Plate Recognition, electronic processing of checks in banks, form processing and, label and barcode recognition. It is essential to have an efficient character segmentation technique because it affects the performance of all the processes that follow and hence, the overall system accuracy. Vertical projection profile is the most common segmentation technique. However, the segmentation results are not always correct in cases where pixels of adjacent characters fall on the same scan line and a minimum threshold is not observed in the histogram to segment the respective adjacent characters. In this study, a character segmentation technique based on Visited Neighbor Pixel (VNP Algorithm is proposed, which is an improvement to the vertical projection profile technique. VNP Algorithm performs segmentation based on the connectedness of the pixels on the scan line with that of the previously visited pixels. Therefore, a clear line of separation is found even when the threshold between two adjacent characters is not minimal. The segmentation results of the traditional vertical projection profile and the proposed method are compared with respect to a few selected fonts and the latter, with an average accuracy of approximately 94%, has shown encouraging results.

  7. A comprehensive segmentation analysis of crude oil market based on time irreversibility

    Science.gov (United States)

    Xia, Jianan; Shang, Pengjian; Lu, Dan; Yin, Yi

    2016-05-01

    In this paper, we perform a comprehensive entropic segmentation analysis of crude oil future prices from 1983 to 2014 which used the Jensen-Shannon divergence as the statistical distance between segments, and analyze the results from original series S and series begin at 1986 (marked as S∗) to find common segments which have same boundaries. Then we apply time irreversibility analysis of each segment to divide all segments into two groups according to their asymmetry degree. Based on the temporal distribution of the common segments and high asymmetry segments, we figure out that these two types of segments appear alternately and do not overlap basically in daily group, while the common portions are also high asymmetry segments in weekly group. In addition, the temporal distribution of the common segments is fairly close to the time of crises, wars or other events, because the hit from severe events to oil price makes these common segments quite different from their adjacent segments. The common segments can be confirmed in daily group series, or weekly group series due to the large divergence between common segments and their neighbors. While the identification of high asymmetry segments is helpful to know the segments which are not affected badly by the events and can recover to steady states automatically. Finally, we rearrange the segments by merging the connected common segments or high asymmetry segments into a segment, and conjoin the connected segments which are neither common nor high asymmetric.

  8. Radial keratotomy associated endothelial degeneration

    Directory of Open Access Journals (Sweden)

    Moshirfar M

    2012-02-01

    Full Text Available Majid Moshirfar, Andrew Ollerton, Rodmehr T Semnani, Maylon HsuJohn A Moran Eye Center, Department of Ophthalmology and Visual Sciences, University of Utah, Salt Lake City, UT, USAPurpose: To describe the presentation and clinical course of eyes with a history of radial keratotomy (RK and varying degrees of endothelial degeneration.Methods: Retrospective case series were used.Results: Thirteen eyes (seven patients were identified with clinical findings of significant guttata and a prior history of RK. The mean age of presentation for cornea evaluation was 54.3 years (range: 38–72 years, averaging 18.7 years (range: 11–33 years after RK. The presentation of guttata varied in degree from moderate to severe. Best corrected visual acuity (BCVA ranged from 20/25 to 20/80. All patients had a history of bilateral RK, except one patient who did not develop any guttata in the eye without prior RK. No patients reported a family history of Fuch’s Dystrophy. One patient underwent a penetrating keratoplasty in one eye and a Descemet’s stripping automated endothelial keratoplasty (DSAEK in the other eye.Conclusions: RK may induce a spectrum of endothelial degeneration. In elderly patients, the findings of guttata may signify comorbid Fuch’s dystrophy in which RK incisions could potentially hasten endothelial decomposition. In these select patients with stable cornea topography and prior RK, DSAEK may successfully treat RK endothelial degeneration.Keywords: radial keratotomy, RK, Descemet’s stripping automated endothelial keratoplasty, DSAEK, guttata, endothelial degeneration, Fuch’s dystrophy

  9. Degenerating the elliptic Schlesinger system

    Science.gov (United States)

    Aminov, G. A.; Artamonov, S. B.

    2013-01-01

    We study various ways of degenerating the Schlesinger system on the elliptic curve with R marked points. We construct a limit procedure based on an infinite shift of the elliptic curve parameter and on shifts of the marked points. We show that using this procedure allows obtaining a nonautonomous Hamiltonian system describing the Toda chain with additional spin sl(N, ℂ) degrees of freedom.

  10. Radial keratotomy associated endothelial degeneration.

    Science.gov (United States)

    Moshirfar, Majid; Ollerton, Andrew; Semnani, Rodmehr T; Hsu, Maylon

    2012-01-01

    To describe the presentation and clinical course of eyes with a history of radial keratotomy (RK) and varying degrees of endothelial degeneration. Retrospective case series were used. Thirteen eyes (seven patients) were identified with clinical findings of significant guttata and a prior history of RK. The mean age of presentation for cornea evaluation was 54.3 years (range: 38-72 years), averaging 18.7 years (range: 11-33 years) after RK. The presentation of guttata varied in degree from moderate to severe. Best corrected visual acuity (BCVA) ranged from 20/25 to 20/80. All patients had a history of bilateral RK, except one patient who did not develop any guttata in the eye without prior RK. No patients reported a family history of Fuch's Dystrophy. One patient underwent a penetrating keratoplasty in one eye and a Descemet's stripping automated endothelial keratoplasty (DSAEK) in the other eye. RK may induce a spectrum of endothelial degeneration. In elderly patients, the findings of guttata may signify comorbid Fuch's dystrophy in which RK incisions could potentially hasten endothelial decomposition. In these select patients with stable cornea topography and prior RK, DSAEK may successfully treat RK endothelial degeneration.

  11. Lumbar disc degeneration below a long arthrodesis (performed for scoliosis in adults) to L4 or L5.

    Science.gov (United States)

    Harding, Ian J; Charosky, Sebastian; Vialle, Raphael; Chopin, Daniel H

    2008-02-01

    A retrospective analysis of adults treated with long instrumented fusion for scoliosis from the thoracic spine proximally to L4 or L5. To evaluate the long-term clinical outcomes as well as radiological changes in distal unfused mobile segments and to evaluate factors that may predispose to distal disc degeneration and/or poor outcome. A total of 151 mobile segments in 85 patients (65 female), mean age 43.2 (range 21-68), were studied. Curve type, number of fused levels and pelvic incidence were recorded. Clinical outcome was measured using the Whitecloud function scale and disc degeneration using the UCLA disc degeneration score. Spinal balance, local segmental angulations and lumbar lordosis were measured pre- and post-operatively as well as at the most recent follow up--mean 9.3 years (range 7-19). A total of 62% of patients had a good or excellent outcome. Eleven had a poor outcome of which ten underwent extension of fusion--five for pain alone, three for pain with stenosis and two for pseudarthroses. Pre-operative disc degeneration was often asymmetric and was slightly greater in older patients. Overall, there was a significant deterioration in disc degeneration (P < 0.0001) that did not correlate with clinical outcome. Disc degeneration correlated with the recent sagittal balance (Anova F = 14.285, P < 0.001) and the most recent lordosis (Anova F = 4.057, P = 0.048). The post-operative sagittal balance and local L5-S1 sagittal angulation correlated to L4 and L5 degeneration, respectively. There was no correlation between degeneration and age, pre-operative degenerative score, pelvic incidence, sacral slope, number of fused levels or distal level of fusion. Disc degeneration does occur below an arthrodesis for scoliosis in adults which does not correlate with clinical outcome. The correlation of loss of sagittal balance with disc degeneration may be as a result of degeneration causing the loss of balance or vice versa, i.e. sagittal imbalance causing

  12. Interobserver error in interpretation of the radiographs for degeneration of the lumbar spine.

    Science.gov (United States)

    Madan, Sanjeev S; Rai, Am; Harley, John M

    2003-01-01

    We examined 114 segments in 23 patients' lumbar spine plain radiographs affected by disc degeneration. Two consultant orthopaedic surgeons, two consultant radiologists, and one spine nurse practitioner made independent observations on the radiographs. MRI scan films of the corresponding 114 segments were used as a gold standard. Kappa coefficients were used to evaluate the interobserver error, and the error between the independent observers and the MRI scanning reports. The systematic differences between the observers for the diagnosis of the disc degeneration at each segment level was recorded. There was significant interobserver error between the independent observers. The pairwise interobserver agreement ranged from fair to substantial on the plain radiograph observations [Weighted kappa coefficient, mean: 0.517 (CI=0.388-0.646)]. The pairwise interobserver agreement between the independent observers and the MRI scan ranged from fair to moderate [Weighted kappa coefficient, mean: 0.388 (CI=0.259-0.518)]. There is significant error in interpretation of the plain radiographs for the diagnosis of lumbar disc degeneration. MRI may be more accurate in the diagnosis of lumbar disc degeneration.

  13. Strategic market segmentation

    National Research Council Canada - National Science Library

    Maričić Branko R; Đorđević Aleksandar

    2015-01-01

    ..., requires segmented approach to the market that appreciates differences in expectations and preferences of customers. One of significant activities in strategic planning of marketing activities is market segmentation...

  14. Handwritten text line segmentation by spectral clustering

    Science.gov (United States)

    Han, Xuecheng; Yao, Hui; Zhong, Guoqiang

    2017-02-01

    Since handwritten text lines are generally skewed and not obviously separated, text line segmentation of handwritten document images is still a challenging problem. In this paper, we propose a novel text line segmentation algorithm based on the spectral clustering. Given a handwritten document image, we convert it to a binary image first, and then compute the adjacent matrix of the pixel points. We apply spectral clustering on this similarity metric and use the orthogonal kmeans clustering algorithm to group the text lines. Experiments on Chinese handwritten documents database (HIT-MW) demonstrate the effectiveness of the proposed method.

  15. Feature Learning Based Random Walk for Liver Segmentation

    Science.gov (United States)

    Zheng, Yongchang; Ai, Danni; Zhang, Pan; Gao, Yefei; Xia, Likun; Du, Shunda; Sang, Xinting; Yang, Jian

    2016-01-01

    Liver segmentation is a significant processing technique for computer-assisted diagnosis. This method has attracted considerable attention and achieved effective result. However, liver segmentation using computed tomography (CT) images remains a challenging task because of the low contrast between the liver and adjacent organs. This paper proposes a feature-learning-based random walk method for liver segmentation using CT images. Four texture features were extracted and then classified to determine the classification probability corresponding to the test images. Seed points on the original test image were automatically selected and further used in the random walk (RW) algorithm to achieve comparable results to previous segmentation methods. PMID:27846217

  16. Intervertebral disc (IVD): Structure, degeneration, repair and regeneration

    Energy Technology Data Exchange (ETDEWEB)

    Whatley, Benjamin R.; Wen Xuejun, E-mail: xjwen@clemson.edu

    2012-02-01

    Low back pain affects a large portion of the population, resulting in high care costs for therapy and treatment. One primary cause of low back pain is the degeneration of the intervertebral disc (IVD) resulting in the compression of the spinal nerves and adjacent vertebrae. Exact causes of degeneration are unknown, but it is thought that natural aging, and both biological and genetic factors may play a significant role in the degenerative process. Conventional methods to alleviate low back pain include spinal fusion and artificial disc replacement. Traditional treatments through spinal fusion may eliminate pain yet do not restore disc function and lead to further degeneration of adjacent levels by altering disc biomechanics and natural kinematics. Recently, artificial IVD replacements have started to gain interest, with two IVD implants currently approved in the United States. Although these implants facilitate the preservation of motions and disc space height, they are unable to sustain compressive forces due to their lack of elasticity. In addition, the implants may produce wear debris that can cause osteolysis and other deleterious effects. As an alternative to these conventional approaches, tissue engineered IVD constructs offer the advantage of biointegration while preserving the essential attributes of natural motion and disc space restoration. There is a great need for the development of tissue engineered scaffolds that simulate the natural 3D morphology and microenvironment of the targeted tissue. Scaffolds should facilitate biological transport to satisfy nutrition and waste removal requirements within the IVD. The discrete tissue architectures of the nucleus pulposus (NP) and annulus fibrosus (AF) have posed great challenges to IVD tissue engineering. Current attempts have not been able to satisfy the biological functions and/or mechanical properties of native tissue. Therefore, these current scaffolds are far from satisfactory. This review highlights the

  17. Determinants of adjacency matrices of graphs

    Directory of Open Access Journals (Sweden)

    Alireza Abdollahi

    2012-12-01

    Full Text Available We study the set of all determinants of adjacency matrices of graphs with a given number of vertices. Using Brendan McKay's data base of small graphs, determinants of graphs with at most $9$ vertices are computed so that the number of non-isomorphic graphs with given vertices whose determinants are all equal to a number is exhibited in a table. Using an idea of M. Newman, it is proved that if $G$ is a graph with $n$ vertices and ${d_1,dots,d_n}$ is the set of vertex degrees of $G$, then $gcd(2m,d^2$ divides the determinant of the adjacency matrix of $G$, where $d=gcd(d_1,dots,d_n$. Possible determinants of adjacency matrices of graphs with exactly two cycles are obtained.

  18. Regularized degenerate multi-solitons

    CERN Document Server

    Correa, Francisco

    2016-01-01

    We report complex PT-symmetric multi-soliton solutions to the Korteweg de-Vries equation that asymptotically contain one-soliton solutions, with each of them possessing the same amount of finite real energy. We demonstrate how these solutions originate from degenerate energy solutions of the Schroedinger equation. Technically this is achieved by the application of Darboux-Crum transformations involving Jordan states with suitable regularizing shifts. Alternatively they may be constructed from a limiting process within the context Hirota's direct method or on a nonlinear superposition obtained from multiple Baecklund transformations. The proposed procedure is completely generic and also applicable to other types of nonlinear integrable systems.

  19. Degenerate Neutrinos and CP Violation

    CERN Document Server

    Ioannisian, A N

    2003-01-01

    We have studied mixing and masses of three left handed Majorana neutrinos in the model, which assumes exactly degenerate neutrino masses at some "neutrino unification" scale. Such a simple theoretical ansatz naturally leads to quasidegenerate neutrinos. The neutrino mass splittings induced by renormalization effects. In the model we found that the parameters of the neutrino physics (neutrino mass spectrum, mixing angles and CP violation phases) are strongly intercorrelated to each other. From these correlations we got strong bounds on the parameters which could be checked in the oscillation experiments.

  20. Radiative seesaw and degenerate neutrinos

    CERN Document Server

    Bajc, B; Bajc, Borut; Senjanovic, Goran

    2005-01-01

    The radiative see-saw mechanism of Witten generates the right-handed neutrino masses in SO(10) with the spinorial 16_H Higgs field. We study here analytically the 2nd and 3rd generations for the minimal Yukawa structure containing 10_H and 120_H Higgs representations. In the approximation of small 2nd generation masses and gauge loop domination we find the following results : (1) b-tau unification, (2) natural coexistence between large theta_l and small theta_q, (3) degenerate neutrinos.

  1. Segmentation Similarity and Agreement

    CERN Document Server

    Fournier, Chris

    2012-01-01

    We propose a new segmentation evaluation metric, called segmentation similarity (S), that quantifies the similarity between two segmentations as the proportion of boundaries that are not transformed when comparing them using edit distance, essentially using edit distance as a penalty function and scaling penalties by segmentation size. We propose several adapted inter-annotator agreement coefficients which use S that are suitable for segmentation. We show that S is configurable enough to suit a wide variety of segmentation evaluations, and is an improvement upon the state of the art. We also propose using inter-annotator agreement coefficients to evaluate automatic segmenters in terms of human performance.

  2. Contextual segment-based classification of airborne laser scanner data

    Science.gov (United States)

    Vosselman, George; Coenen, Maximilian; Rottensteiner, Franz

    2017-06-01

    Classification of point clouds is needed as a first step in the extraction of various types of geo-information from point clouds. We present a new approach to contextual classification of segmented airborne laser scanning data. Potential advantages of segment-based classification are easily offset by segmentation errors. We combine different point cloud segmentation methods to minimise both under- and over-segmentation. We propose a contextual segment-based classification using a Conditional Random Field. Segment adjacencies are represented by edges in the graphical model and characterised by a range of features of points along the segment borders. A mix of small and large segments allows the interaction between nearby and distant points. Results of the segment-based classification are compared to results of a point-based CRF classification. Whereas only a small advantage of the segment-based classification is observed for the ISPRS Vaihingen dataset with 4-7 points/m2, the percentage of correctly classified points in a 30 points/m2 dataset of Rotterdam amounts to 91.0% for the segment-based classification vs. 82.8% for the point-based classification.

  3. Macular Degeneration Prevention and Risk Factors

    Science.gov (United States)

    ... Grant Terms & Conditions Patent & Intellectual Property Policy For Current Awardees FAQs Our Funding Philosophy ... Alzheimer’s Disease Research Macular Degeneration Research National Glaucoma Research ...

  4. [Pathogenesis of age-related macular degeneration].

    Science.gov (United States)

    Kaarniranta, Kai; Seitsonen, Sanna; Paimela, Tuomas; Meri, Seppo; Immonen, Ilkka

    2009-01-01

    Age-related macular degeneration is a multiform disease of the macula, the region responsible for detailed central vision. In recent years, plenty of new knowledge of the pathogenesis of this disease has been obtained, and the treatment of exudative macular degeneration has greatly progressed. The number of patients with age-related macular degeneration will multiply in the following decades, because knowledge of mechanisms of development of macular degeneration that could be subject to therapeutic measures is insufficient. Central underlying factors are genetic inheritance, exposure of the retina to chronic oxidative stress and accumulation of inflammation-inducing harmful proteins into or outside of retinal cells.

  5. Structure of Degenerate Block Algebras

    Institute of Scientific and Technical Information of China (English)

    Linsheng Zhu; Daoji Meng

    2003-01-01

    Given a non-trivial torsion-free abelian group (A,+,0), a field F of characteristic 0, and a non-degenerate bi-additive skew-symmetric map φ :A × A → F, we define a Lie algebra ∑ = ∑(A, φ) over F with basis {ex | x ∈ A\\{0}}and Lie product [ex, ey] = φ(x, y)ex+y. We show that ∑ is endowed uniquely with a non-degenerate symmetric invariant bilinear form and the derivation algebra Der ∑ of ∑ is a complete Lie algebra. We describe the double extension D(∑, T) of ∑ by T, where T is spanned by the locally finite derivations of ∑, and determine the second cohomology group H2(D(∑,T),F) using anti-derivations related to the form on D(∑, T). Finally, we compute the second Leibniz cohomology groups HL2(∑, F) and HL2(D(∑, T), F).

  6. Significant relationship between local angle at fused segments and C2-7 angle: Average duration of longer than 20 years after anterior cervical discectomy and fusion

    Directory of Open Access Journals (Sweden)

    T Nagata

    2011-01-01

    Full Text Available Background : The authors have focused their attention to the radiological durability of cervical sagittal alignment after anterior cervical discectomy and fusion (ACDF using autologous bone grafting. Materials and Methods : Among the patients who underwent ACDF with trans-unco-discal (TUD approach between 1976 and 1997, 22 patients (16 males and 6 females made return visits for a clinical evaluation. Patients with trauma or previously treated by anterior cervical fusion or by posterior decompression were excluded from the present study. Clinical evaluation included adjacent segment degeneration (ASD, osseous fusion, local angle at the fused segments and C2-7 angle of cervical spine. Results : The duration after ACDF ranged from 13 to 34 years with an average of 21.3 ± 7.0 years. A single level fusion was done on 8 patients, 2 levels on 11 patients, 3 levels on 2 patients, and 4 levels on 1 patient. Imaging studies indicated that 12 of the 22 patients (54.5% were graded as having symptomatic ASD. Osseous bony fusion at ACDF was recognized in all cases. None of the patients demonstrated kyphotic malalignment of the cervical spine. Average degrees of local angle at the fused segments and the C2-7 angle were 7.06 and 17.6, respectively. Statistical analysis indicated a significant relationship between the local at the fused segments and C2-7 angles. Conclusions : Sagittal alignment of the cervical spine was durable long after ACDF when the local angle at the fused segments was well stabilized.

  7. THREE-DIMENSIONAL VISU ALIZATION OF DEGENERATE FERRITE FORMED BELOW TTT-DIAGRAM BAY IN AN Fe-C-Mo ALLOY

    Institute of Scientific and Technical Information of China (English)

    K.M. Wu; M. Enomoto

    2003-01-01

    The evolution of degenerate ferrite in an Fe-0.28wt%C-3.0wt%Mo alloy isothermally reacted for 10ks at 20℃ below TTT diagram bay temperature have been revealed utilizing serial sectioning in conjunction with computer reconstruction and visualization.The degenerate ferrite is initially formed at prior austenite boundary and then grows toward grain interior rather than along the grain boundary. The degenerate morphology of ferrite may be attributed to repeated nucleation, growth and coalescence of adjacent ferrite crystals. The shape of individual ferrite crystals appears to be rod-like.

  8. Pituitary Adenoma Segmentation

    CERN Document Server

    Egger, Jan; Kuhnt, Daniela; Freisleben, Bernd; Nimsky, Christopher

    2011-01-01

    Sellar tumors are approximately 10-15% among all intracranial neoplasms. The most common sellar lesion is the pituitary adenoma. Manual segmentation is a time-consuming process that can be shortened by using adequate algorithms. In this contribution, we present a segmentation method for pituitary adenoma. The method is based on an algorithm we developed recently in previous work where the novel segmentation scheme was successfully used for segmentation of glioblastoma multiforme and provided an average Dice Similarity Coefficient (DSC) of 77%. This scheme is used for automatic adenoma segmentation. In our experimental evaluation, neurosurgeons with strong experiences in the treatment of pituitary adenoma performed manual slice-by-slice segmentation of 10 magnetic resonance imaging (MRI) cases. Afterwards, the segmentations were compared with the segmentation results of the proposed method via the DSC. The average DSC for all data sets was 77.49% +/- 4.52%. Compared with a manual segmentation that took, on the...

  9. Quantitative Assessment of Image Segmentation Quality by Random Walk Relaxation Times

    Science.gov (United States)

    Andres, Björn; Köthe, Ullrich; Bonea, Andreea; Nadler, Boaz; Hamprecht, Fred A.

    The purpose of image segmentation is to partition the pixel grid of an image into connected components termed segments such that (i) each segment is homogenous and (ii) for any pair of adjacent segments, their union is not homogenous. (If it were homogenous the segments should be merged). We propose a rigorous definition of segment homogeneity which is scale-free and adaptive to the geometry of segments. We motivate this definition using random walk theory and show how segment homogeneity facilitates the quantification of violations of the conditions (i) and (ii) which are referred to as under-segmentation and over-segmentation, respectively. We describe the theoretical foundations of our approach and present a proof of concept on a few natural images.

  10. Hierarchical Subtopic Segmentation of Web Document

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The paper proposes a novel method for subtopics segmentation of Web document. An effective retrieval results may be obtained by using subtopics segmentation. The proposed method can segment hierarchically subtopics and identify the boundary of each subtopic. Based on the term frequency matrix, the method measures the similarity between adjacent blocks, such as paragraphs, passages. In the real-world sample experiment, the macro-averaged precision and recall reach 73.4% and 82.5%, and the micro-averaged precision and recall reach 72.9% and 83.1%. Moreover, this method is equally efficient to other Asian languages such as Japanese and Korean, as well as other western languages.

  11. Genetic association studies in lumbar disc degeneration

    DEFF Research Database (Denmark)

    Eskola, Pasi J; Lemmelä, Susanna; Kjaer, Per

    2012-01-01

    Low back pain is associated with lumbar disc degeneration, which is mainly due to genetic predisposition. The objective of this study was to perform a systematic review to evaluate genetic association studies in lumbar disc degeneration as defined on magnetic resonance imaging (MRI) in humans....

  12. Degenerated differential pair with controllable transconductance

    NARCIS (Netherlands)

    Mensink, Clemens; Mensink, Clemens H.J.; Nauta, Bram

    1998-01-01

    A differential pair with input transistors and provided with a variable degeneration resistor. The degeneration resistor comprises a series arrangement of two branches of coupled resistors which are shunted in mutually corresponding points by respective control transistors whose gates are interconne

  13. Regularized degenerate multi-solitons

    Science.gov (United States)

    Correa, Francisco; Fring, Andreas

    2016-09-01

    We report complex {P}{T} -symmetric multi-soliton solutions to the Korteweg de-Vries equation that asymptotically contain one-soliton solutions, with each of them possessing the same amount of finite real energy. We demonstrate how these solutions originate from degenerate energy solutions of the Schrödinger equation. Technically this is achieved by the application of Darboux-Crum transformations involving Jordan states with suitable regularizing shifts. Alternatively they may be constructed from a limiting process within the context Hirota's direct method or on a nonlinear superposition obtained from multiple Bäcklund transformations. The proposed procedure is completely generic and also applicable to other types of nonlinear integrable systems.

  14. Naturalness of nearly degenerate neutrinos

    CERN Document Server

    Casas, J A; Ibarra, Alejandro; Navarro, I

    1999-01-01

    If neutrinos are to play a relevant cosmological role, they must be essentially degenerate. We study whether radiative corrections can or cannot be responsible for the small mass splittings, in agreement with all the available experimental data. We perform an exhaustive exploration of the bimaximal mixing scenario, finding that (i) the vacuum oscillations solution to the solar neutrino problem is always excluded; (ii) if the mass matrix is produced by a see-saw mechanism, there are large regions of the parameter space consistent with the large angle MSW solution, providing a natural origin for the Delta m^2_{sol} << Delta m^2_{atm} hierarchy; (iii) the bimaximal structure becomes then stable under radiative corrections. We also provide analytical expressions for the mass splittings and mixing angles and present a particularly simple see-saw ansatz consistent with all the observations.

  15. Degenerate doping of metallic anodes

    Science.gov (United States)

    Friesen, Cody A; Zeller, Robert A; Johnson, Paul B; Switzer, Elise E

    2015-05-12

    Embodiments of the invention relate to an electrochemical cell comprising: (i) a fuel electrode comprising a metal fuel, (ii) a positive electrode, (iii) an ionically conductive medium, and (iv) a dopant; the electrodes being operable in a discharge mode wherein the metal fuel is oxidized at the fuel electrode and the dopant increases the conductivity of the metal fuel oxidation product. In an embodiment, the oxidation product comprises an oxide of the metal fuel which is doped degenerately. In an embodiment, the positive electrode is an air electrode that absorbs gaseous oxygen, wherein during discharge mode, oxygen is reduced at the air electrode. Embodiments of the invention also relate to methods of producing an electrode comprising a metal and a doped metal oxidation product.

  16. Min-cut segmentation of cursive handwriting in tabular documents

    Science.gov (United States)

    Davis, Brian L.; Barrett, William A.; Swingle, Scott D.

    2015-01-01

    Handwritten tabular documents, such as census, birth, death and marriage records, contain a wealth of information vital to genealogical and related research. Much work has been done in segmenting freeform handwriting, however, segmentation of cursive handwriting in tabular documents is still an unsolved problem. Tabular documents present unique segmentation challenges caused by handwriting overlapping cell-boundaries and other words, both horizontally and vertically, as "ascenders" and "descenders" overlap into adjacent cells. This paper presents a method for segmenting handwriting in tabular documents using a min-cut/max-flow algorithm on a graph formed from a distance map and connected components of handwriting. Specifically, we focus on line, word and first letter segmentation. Additionally, we include the angles of strokes of the handwriting as a third dimension to our graph to enable the resulting segments to share pixels of overlapping letters. Word segmentation accuracy is 89.5% evaluating lines of the data set used in the ICDAR2013 Handwriting Segmentation Contest. Accuracy is 92.6% for a specific application of segmenting first and last names from noisy census records. Accuracy for segmenting lines of names from noisy census records is 80.7%. The 3D graph cutting shows promise in segmenting overlapping letters, although highly convoluted or overlapping handwriting remains an ongoing challenge.

  17. Enteroenteroanastomosis near adjacent ileocecal valve in infants

    Institute of Scientific and Technical Information of China (English)

    Wei-Wei Jiang; Xiao-Qun Xu; Qi-Ming Geng; Jie Zhang; Huan Chen; Xiao-Feng Lv; Chang-Gui Lu

    2012-01-01

    AIM:To investigate the feasibility and the effectiveness of ileoileostomy in the region adjacent to the ileocecal valve,which can retain the ileocecal valve in infants.METHODS:This is a retrospective review of 48 patients who underwent ileoileostomy in the region adjacent to the ileocecal valve (group 1) and 34 patients who underwent ileocecal resections and ileotransversanastomosis (group 2).Patients were monitored for the time to flatus,resumption of eating,length of hospital stay after surgery,serum total bile acid,vitamin B12 and postoperative complications.RESULTS:The time to flatus,time until resumption of eating and post-operative length of hospital stay showed no statistically significant differences between the two groups.Serum total bile acid and vitamin B12 were not significantly different between the two groups at post-operative day 1 and day 3,but were significantly decreased at 1 wk after operation in group 2.None of the patients died or suffered from stomal leak in these two groups.However,the incidence of diarrhea,intestinal infection,disturbance of acid-base balance and water-electrolytes in group 1 was lower than in group 2.CONCLUSION:Ileoileostomy in the region adjacent to the ileocecal valve is safe and results in fewer complications than ileotransversanastomosis in infants.

  18. Enteroenteroanastomosis near adjacent ileocecal valve in infants

    Science.gov (United States)

    Jiang, Wei-Wei; Xu, Xiao-Qun; Geng, Qi-Ming; Zhang, Jie; Chen, Huan; Lv, Xiao-Feng; Lu, Chang-Gui; Tang, Wei-Bing

    2012-01-01

    AIM: To investigate the feasibility and the effectiveness of ileoileostomy in the region adjacent to the ileocecal valve, which can retain the ileocecal valve in infants. METHODS: This is a retrospective review of 48 patients who underwent ileoileostomy in the region adjacent to the ileocecal valve (group 1) and 34 patients who underwent ileocecal resections and ileotransversanastomosis (group 2). Patients were monitored for the time to flatus, resumption of eating, length of hospital stay after surgery, serum total bile acid, vitamin B12 and postoperative complications. RESULTS: The time to flatus, time until resumption of eating and post-operative length of hospital stay showed no statistically significant differences between the two groups. Serum total bile acid and vitamin B12 were not significantly different between the two groups at post-operative day 1 and day 3, but were significantly decreased at 1 wk after operation in group 2. None of the patients died or suffered from stomal leak in these two groups. However, the incidence of diarrhea, intestinal infection, disturbance of acid-base balance and water-electrolytes in group 1 was lower than in group 2. CONCLUSION: Ileoileostomy in the region adjacent to the ileocecal valve is safe and results in fewer complications than ileotransversanastomosis in infants. PMID:23326139

  19. [Atmospheric adjacency effect correction of ETM images].

    Science.gov (United States)

    Liu, Cheng-yu; Chen, Chun; Zhang, Shu-qing; Gao, Ji-yue

    2010-09-01

    It is an important precondition to retrieve the ground surface reflectance exactly for improving the subsequent product of remote sensing images and the quantitative application of remote sensing. However, because the electromagnetic wave is scattered by the atmosphere during its transmission from the ground surface to the sensor, the electromagnetic wave signal of the target received by the sensor contained the signal of the background. The adjacency effect emerges. Because of the adjacency effect, the remote sensing images become blurry, and their contrast reduces. So the ground surface reflectance retrieved from the remote sensing images is also inaccurate. Finally, the quality of subsequent product of remote sensing images and the accuracy of quantitative application of remote sensing might decrease. In the present paper, according to the radiative transfer equation, the atmospheric adjacency effect correction experiment of ETM images was carried out by using the point spread function method. The result of the experiment indicated that the contrast of the corrected ETM images increased, and the ground surface reflectance retrieved from those images was more accurate.

  20. The effect of different lumbar segmental fixation on lumbar activity and intervertebral pressure%腰椎不同节段固定对腰椎活动度及椎间压力的影响

    Institute of Scientific and Technical Information of China (English)

    张志敏; 苏峰; 张春林; 马朋朋; 张瑛; 张晓平

    2013-01-01

    Objective To study the changes of inferior adjacent segmental after different segmental fixation ,and to analyze the accelerating mechanism of the adjacent segment degeneration .Methods Sixty sheep lumbar spine specimens (Waist 1 vertebral body-S5) with pedicle screws were collected ,according to the different fixed section ,they were divided into complete control group(not fixed) ,L6-L7 single segment fixed group ,L5-L7 short segmental fixed group ,L3-L7 long segmental fixed group .The biomechan-ical experiment was measured in the 6 N · m torque loading ,L7-S1 sacral vertebra clearance were measured in different fixed sec-tion .Results Applied in fixed ,beneath the adjacent segment in the stretch direction of angular displacement ,intervertebral disc pressure was increased significantly ,amplitude in creased with the increase of fixed range .The difference between groups was sta-tistically significant(P< 0 .05) .Conclusion After fixing spine in pedicle screws ,the longer the segmentation is fixed ,the more effect it has on subjacent segment degeneration .%目的:研究不同节段腰椎内固定后对下位相邻节段退变加速发生过程的影响。方法60具绵羊腰段脊柱标本:取腰1椎体-骶5,以椎弓根螺钉固定,依据固定节段的不同分为完整对照组(未固定)、L6~L7单节段固定组、L5~ L7短节段固定组、L3~L7长节段固定组。本实验为自身对照实验,在6 N · m (牛顿·米)力矩加载下进行生物力学测定,比较各组在椎弓根螺钉进行不同节段固定下腰7骶1节段的变化。结果施加内固定后,下方相邻节段在屈伸方向上的活动度、椎间盘压力都明显增加,增加幅度随着固定范围的增大而增大,各组间差异有统计学意义(P<0.05)。结论固定节段越长,椎弓根钉内固定对下方邻近节段退变的影响越大。

  1. GPS Control Segment

    Science.gov (United States)

    2015-04-29

    Luke J. Schaub Chief, GPS Control Segment Division 29 Apr 15 GPS Control Segment Report Documentation Page Form ApprovedOMB No. 0704-0188...00-2015 4. TITLE AND SUBTITLE GPS Control Segment 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT...Center, GPS Control Segment Division,Los Angeles AFB, El Segundo,CA,90245 8. PERFORMING ORGANIZATION REPORT NUMBER 9. SPONSORING/MONITORING AGENCY NAME(S

  2. Sipunculans and segmentation

    DEFF Research Database (Denmark)

    Wanninger, Andreas; Kristof, Alen; Brinkmann, Nora

    2009-01-01

    Comparative molecular, developmental and morphogenetic analyses show that the three major segmented animal groups- Lophotrochozoa, Ecdysozoa and Vertebrata-use a wide range of ontogenetic pathways to establish metameric body organization. Even in the life history of a single specimen, different...... plasticity and potential evolutionary lability of segmentation nourishes the controversy of a segmented bilaterian ancestor versus multiple independent evolution of segmentation in respective metazoan lineages....

  3. Automatic Melody Segmentation

    NARCIS (Netherlands)

    Rodríguez López, Marcelo

    2016-01-01

    The work presented in this dissertation investigates music segmentation. In the field of Musicology, segmentation refers to a score analysis technique, whereby notated pieces or passages of these pieces are divided into “units” referred to as sections, periods, phrases, and so on. Segmentation analy

  4. Muscle gap approach under a minimally invasive channel technique for treating long segmental lumbar spinal stenosis: A retrospective study.

    Science.gov (United States)

    Bin, Yang; De Cheng, Wang; Wei, Wang Zong; Hui, Li

    2017-08-01

    This study aimed to compare the efficacy of muscle gap approach under a minimally invasive channel surgical technique with the traditional median approach.In the Orthopedics Department of Traditional Chinese and Western Medicine Hospital, Tongzhou District, Beijing, 68 cases of lumbar spinal canal stenosis underwent surgery using the muscle gap approach under a minimally invasive channel technique and a median approach between September 2013 and February 2016. Both approaches adopted lumbar spinal canal decompression, intervertebral disk removal, cage implantation, and pedicle screw fixation. The operation time, bleeding volume, postoperative drainage volume, and preoperative and postoperative visual analog scale (VAS) score and Japanese Orthopedics Association score (JOA) were compared between the 2 groups.All patients were followed up for more than 1 year. No significant difference between the 2 groups was found with respect to age, gender, surgical segments. No diversity was noted in the operation time, intraoperative bleeding volume, preoperative and 1 month after the operation VAS score, preoperative and 1 month after the operation JOA score, and 6 months after the operation JOA score between 2 groups (P > .05). The amount of postoperative wound drainage (260.90 ± 160 mL vs 447.80 ± 183.60 mL, P gap approach group than in the median approach group (P gap approach under a minimally invasive channel group, the average drainage volume was reduced by 187 mL, and the average VAS score 6 months after the operation was reduced by an average of 0.48.The muscle gap approach under a minimally invasive channel technique is a feasible method to treat long segmental lumbar spinal canal stenosis. It retains the integrity of the posterior spine complex to the greatest extent, so as to reduce the adjacent spinal segmental degeneration and soft tissue trauma. Satisfactory short-term and long-term clinical results were obtained.

  5. Radiation-induced chorioretinal degeneration: a clinicopathological report of three cases.

    Science.gov (United States)

    Sefau, Suleiman O A; Dorey, Michael W; Brownstein, Seymour; Romanchuk, Ken; Little, John M; Chisholm, Ian A

    2003-02-01

    With the shift in radiotherapy toward the posterior segment and with the use of lead screens to shield the anterior segment, posterior segment lesions have become more readily recognized. The purpose of this study is to highlight the effects of ionizing radiation on the choroid and to demonstrate how this can result in visual loss, particularly if the macula is involved. Histopathological study of three enucleated eyes of three patients who had received ionizing radiation: a 27-year-old woman who had received radiation as a child for a hemangioma of the left side of the face, a 16-year-old girl who had received radiation at age 11 years for a malignant mesenchymoma of the right maxilla, and a 4-year-old girl who had received radiation at age 1 year for a retinoblastoma of the right eye. Histopathological examination of the three globes showed extensive chorioretinal degeneration, among other ocular findings. In all cases the fellow eye did not show similar chorioretinal lesions. As all three patients were relatively young, the degree of chorioretinal degeneration was considered to be secondary to radiation treatment. Vascular damage from ionizing radiation is not limited to the retina. It can also affect the choroid in the form of chorioretinal degeneration. Since most of the intraocular circulation arises from the uveal vessels, chorioretinal degenerative lesions may be extensive and may even involve the macula.

  6. Lack of Acid Sphingomyelinase Induces Age-Related Retinal Degeneration.

    Directory of Open Access Journals (Sweden)

    Bill X Wu

    Full Text Available Mutations of acid sphingomyelinase (ASMase cause Niemann-Pick diseases type A and B, which are fatal inherited lipid lysosomal storage diseases, characterized with visceral organ abnormalities and neurodegeneration. However, the effects of suppressing retinal ASMase expression are not understood. The goal of this study was to determine if the disruption of ASMase expression impacts the retinal structure and function in the mouse, and begin to investigate the mechanisms underlying these abnormalities.Acid sphingomyelinase knockout (ASMase KO mice were utilized to study the roles of this sphingolipid metabolizing enzyme in the retina. Electroretinogram and morphometric analysis were used to assess the retinal function and structure at various ages. Sphingolipid profile was determined by liquid chromatography-mass spectrometry. Western blots evaluated the level of the autophagy marker LC3-II.When compared to control animals, ASMase KO mice exhibited significant age-dependent reduction in ERG a- and b-wave amplitudes. Associated with these functional deficits, morphometric analysis revealed progressive thinning of retinal layers; however, the most prominent degeneration was observed in the photoreceptor and outer nuclear layer. Additional analyses of ASMase KO mice revealed early reduction in ERG c-wave amplitudes and increased lipofuscin accumulation in the retinal pigment epithelium (RPE. Sphingolipid analyses showed abnormal accumulation of sphingomyelin and sphingosine in ASMase KO retinas. Western blot analyses showed a higher level of the autophagosome marker LC3-II.These studies demonstrate that ASMase is necessary for the maintenance of normal retinal structure and function. The early outer retinal dysfunction, outer segment degeneration, accumulation of lipofuscin and autophagosome markers provide evidence that disruption of lysosomal function contributes to the age-dependent retinal degeneration exhibited by ASMase KO mice.

  7. Ccdc66 null mutation causes retinal degeneration and dysfunction.

    Science.gov (United States)

    Gerding, Wanda M; Schreiber, Sabrina; Schulte-Middelmann, Tobias; de Castro Marques, Andreia; Atorf, Jenny; Akkad, Denis A; Dekomien, Gabriele; Kremers, Jan; Dermietzel, Rolf; Gal, Andreas; Rülicke, Thomas; Ibrahim, Saleh; Epplen, Jörg T; Petrasch-Parwez, Elisabeth

    2011-09-15

    Retinitis pigmentosa (RP) is a group of human retinal disorders, with more than 100 genes involved in retinal degeneration. Canine and murine models are useful for investigating human RP based on known, naturally occurring mutations. In Schapendoes dogs, for example, a mutation in the CCDC66 gene has been shown to cause autosomal recessively inherited, generalized progressive retinal atrophy (gPRA), the canine counterpart to RP. Here, a novel mouse model with a disrupted Ccdc66 gene was investigated to reveal the function of protein CCDC66 and the pathogenesis of this form of gPRA. Homozygous Ccdc66 mutant mice lack retinal Ccdc66 RNA and protein expression. Light and electron microscopy reveal an initial degeneration of photoreceptors already at 13 days of age, followed by a slow, progressive retinal degeneration over months. Retinal dysfunction causes reduced scotopic a-wave amplitudes, declining from 1 to 7 months of age as well as an early reduction of the photopic b-wave at 1 month, improving slightly at 7 months, as evidenced by electroretinography. In the retina of the wild-type (WT) mouse, protein CCDC66 is present at highest levels after birth, followed by a decline until adulthood, suggesting a crucial role in early development. Protein CCDC66 is expressed predominantly in the developing rod outer segments as confirmed by subcellular analyses. These findings illustrate that the lack of protein CCDC66 causes early, slow progressive rod-cone dysplasia in the novel Ccdc66 mutant mouse model, thus providing a sound foundation for the development of therapeutic strategies.

  8. Image segmentation by connectivity preserving relinking in hierarchical graph structures

    NARCIS (Netherlands)

    Nacken, P.F.M.

    1995-01-01

    The method of image segmentation by pyramid relinking is extended to the formalism of hierarchies of region adjacency graphs. This approach has a number of advantages: (1) resulting regions are connected; (2) the method is adaptive, and therefore artifacts caused by a regular grid are avoided; and (

  9. Modified gravitational instability of degenerate and non-degenerate dusty plasma

    Science.gov (United States)

    Jain, Shweta; Sharma, Prerana

    2016-09-01

    The gravitational instability of strongly coupled dusty plasma (SCDP) is studied considering degenerate and non-degenerate dusty plasma situations. The SCDP system is assumed to be composed of the electrons, ions, neutrals, and strongly coupled dust grains. First, in the high density regime, due to small interparticle distance, the electrons are considered degenerate, whereas the neutrals, dust grains, and ions are treated non-degenerate. In this case, the dynamics of inertialess electrons are managed by Fermi pressure and Bohm potential, while the inertialess ions are by only thermal pressure. Second, in the non-degenerate regime, both the electrons and ions are governed by the thermal pressure. The generalized hydrodynamic model and the normal mode analysis technique are employed to examine the low frequency waves and gravitational instability in both degenerate and non-degenerate cases. The general dispersion relation is discussed for a characteristic timescale which provides two regimes of frequency, i.e., hydrodynamic regime and kinetic regime. Analytical solutions reveal that the collisions reduce the growth rate and have a strong impact on structure formation in both degenerate and non-degenerate circumstances. Numerical estimation on the basis of observed parameters for the degenerate and non-degenerate cases is presented to show the effects of dust-neutral collisions and dust effective velocity in the presence of polarization force. The values of Jeans length and Jeans mass have been estimated for degenerate white dwarfs as Jeans length L J = 1.3 × 10 5 cm and Jeans mass M J = 0.75 × 10 - 3 M⊙ and for non-degenerate laboratory plasma Jeans length L J = 6.86 × 10 16 cm and Jeans mass M J = 0.68 × 10 10 M⊙. The stability of the SCDP system is discussed using the Routh-Hurwitz criterion.

  10. Imaging of Lesser Metatarsophalangeal Joint Plantar Plate Degeneration, Tear, and Repair.

    Science.gov (United States)

    Linklater, James M; Bird, Stephen J

    2016-04-01

    Plantar plate degeneration and tear is a common cause of forefoot pain, typically involving the second metatarsophalangeal joint at the proximal phalangeal insertion laterally, frequently confused with the second web space Morton neuroma. The condition has received increased attention with the development of surgical techniques that can result in successful repair of the plantar plate and substantial improvement in patient symptoms. High-resolution MRI or ultrasound can confirm a diagnosis of plantar plate degeneration and tear and exclude other pathologies, particularly Morton neuroma. The normal plantar plate is a mildly hyperechoic structure on ultrasound and is hypointense on all conventional MR sequences. Plantar plate degeneration manifests on ultrasound as hypoechoic echotextural change and on MRI as mild signal hyperintensity on short TE sequences, becoming less conspicuous on long TE sequences. Adjacent entheseal bony irregularity is commonly present. Plantar plate tears on ultrasound may be seen as an anechoic cleft defect or area of heterogeneous echotexture, sometimes more conspicuous with dorsiflexion stress. Plantar plate tears demonstrate greater signal hyperintensity on proton-density sequences, becoming more conspicuous on fat-suppressed proton density and T2-weighted sequences. Edema and fibrotic change in the pericapsular fat plane is commonly seen in the setting of an adjacent plantar plate tear and should not be misinterpreted as reflecting a Morton neuroma.

  11. Regularity extraction from non-adjacent sounds

    Directory of Open Access Journals (Sweden)

    Alexandra eBendixen

    2012-05-01

    Full Text Available The regular behavior of sound sources helps us to make sense of the auditory environment. Regular patterns may, for instance, convey information on the identity of a sound source (such as the acoustic signature of a train moving on the rails. Yet typically, this signature overlaps in time with signals emitted from other sound sources. It is generally assumed that auditory regularity extraction cannot operate upon this mixture of signals because it only finds regularities between adjacent sounds. In this view, the auditory environment would be grouped into separate entities by means of readily available acoustic cues such as separation in frequency and location. Regularity extraction processes would then operate upon the resulting groups. Our new experimental evidence challenges this view. We presented two interleaved sound sequences which overlapped in frequency range and shared all acoustic parameters. The sequences only differed in their underlying regular patterns. We inserted deviants into one of the sequences to probe whether the regularity was extracted. In the first experiment, we found that these deviants elicited the mismatch negativity (MMN component. Thus the auditory system was able to find the regularity between the non-adjacent sounds. Regularity extraction was not influenced by sequence cohesiveness as manipulated by the relative duration of tones and silent inter-tone-intervals. In the second experiment, we showed that a regularity connecting non-adjacent sounds was discovered only when the intervening sequence also contained a regular pattern, but not when the intervening sounds were randomly varying. This suggests that separate regular patterns are available to the auditory system as a cue for identifying signals coming from distinct sound sources. Thus auditory regularity extraction is not necessarily confined to a processing stage after initial sound grouping, but may precede grouping when other acoustic cues are unavailable.

  12. A Monte Carlo algorithm for degenerate plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Turrell, A.E., E-mail: a.turrell09@imperial.ac.uk; Sherlock, M.; Rose, S.J.

    2013-09-15

    A procedure for performing Monte Carlo calculations of plasmas with an arbitrary level of degeneracy is outlined. It has possible applications in inertial confinement fusion and astrophysics. Degenerate particles are initialised according to the Fermi–Dirac distribution function, and scattering is via a Pauli blocked binary collision approximation. The algorithm is tested against degenerate electron–ion equilibration, and the degenerate resistivity transport coefficient from unmagnetised first order transport theory. The code is applied to the cold fuel shell and alpha particle equilibration problem of inertial confinement fusion.

  13. Horizon Supertranslation and Degenerate Black Hole Solution

    CERN Document Server

    Cai, Rong-Gen; Zhang, Yun-Long

    2016-01-01

    In this note we first review the degenerate vacua arising from the BMS symmetries. According to the discussion in [1] one can define BMS-analogous supertranslation and superrotation for spacetime with black hole in Gaussian null coordinates. In the leading and subleading orders of near horizon approximation, the infinitely degenerate black hole solutions are derived by considering Einstein equations with or without cosmological constant, and they are related to each other by the diffeomorphism generated by horizon supertranslation. Higher order results and degenerate Rindler horizon solutions also are given in appendices.

  14. Age-related macular degeneration: prevention and treatment. A review

    Directory of Open Access Journals (Sweden)

    K. A. Mirzabekova

    2014-07-01

    Full Text Available Age-related macular degeneration (AMD is a multifactorial disease. Age, light exposure, smoking, melanin levels and low-antioxidant diet are contributed to AMD development and progression. Cardiovascular disorders are of considerable importance as well. In macula, photoreceptor outer segments that are rich in polyunsaturated fatty acids (FA, particularly, docosahexaenoic acid (DHA, are susceptible to free radicals damage. High blood flow velocity and oxygen partial pressure as well as direct sunlight exposure induce oxidative processes. The source of free radicals in photoreceptor cells and retinal pigment epithelium (RPE is an extensive mitochondrial metabolism, photoreceptor outer segments phagocytosis, lipofuscin phototoxic activity and hemoglobin or protoporphyrin precursors photosensitization. Oxidative stress is considered as an universal component of cell depth in necrosis, apoptosis and toxic damage. Antioxidant protective system consists of enzymes (superoxide dismutase, glutathione peroxidase and catalase and non-enzymatic factors (ascorbic acid, alpha tocopherol, retinol, carotenoids. Specific antioxidant food supplement containing ascorbic acid (500 mg, vitamin E (400 IU and beta carotene (15 mg coupled with zinc (80 mg of zinc oxide and copper (2 mg of copper oxide results in 25 % decrease in late-stage AMD development rate. Amongst the agents that can protect retina from oxidative stress and AMD development, carotenoids are of special importance. Lutein and zeaxanthin containing in retina and lens screen blue light from central area of the retina. They also absorb blue light and inhibit free radicals generation thus preventing polyunsaturated FA light destruction. Association between lutein and zeaxanthin intake and late-stage AMD risk was revealed. Amongst the most important factors which deficiency favors macular degeneration are omega-3 FAs, i.e., DHA. DHA is the key component of visual pigment rhodopsin transformation. It

  15. Age-related macular degeneration: prevention and treatment. A review

    Directory of Open Access Journals (Sweden)

    K. A. Mirzabekova

    2014-01-01

    Full Text Available Age-related macular degeneration (AMD is a multifactorial disease. Age, light exposure, smoking, melanin levels and low-antioxidant diet are contributed to AMD development and progression. Cardiovascular disorders are of considerable importance as well. In macula, photoreceptor outer segments that are rich in polyunsaturated fatty acids (FA, particularly, docosahexaenoic acid (DHA, are susceptible to free radicals damage. High blood flow velocity and oxygen partial pressure as well as direct sunlight exposure induce oxidative processes. The source of free radicals in photoreceptor cells and retinal pigment epithelium (RPE is an extensive mitochondrial metabolism, photoreceptor outer segments phagocytosis, lipofuscin phototoxic activity and hemoglobin or protoporphyrin precursors photosensitization. Oxidative stress is considered as an universal component of cell depth in necrosis, apoptosis and toxic damage. Antioxidant protective system consists of enzymes (superoxide dismutase, glutathione peroxidase and catalase and non-enzymatic factors (ascorbic acid, alpha tocopherol, retinol, carotenoids. Specific antioxidant food supplement containing ascorbic acid (500 mg, vitamin E (400 IU and beta carotene (15 mg coupled with zinc (80 mg of zinc oxide and copper (2 mg of copper oxide results in 25 % decrease in late-stage AMD development rate. Amongst the agents that can protect retina from oxidative stress and AMD development, carotenoids are of special importance. Lutein and zeaxanthin containing in retina and lens screen blue light from central area of the retina. They also absorb blue light and inhibit free radicals generation thus preventing polyunsaturated FA light destruction. Association between lutein and zeaxanthin intake and late-stage AMD risk was revealed. Amongst the most important factors which deficiency favors macular degeneration are omega-3 FAs, i.e., DHA. DHA is the key component of visual pigment rhodopsin transformation. It

  16. What is a segment?

    Science.gov (United States)

    Hannibal, Roberta L; Patel, Nipam H

    2013-12-17

    Animals have been described as segmented for more than 2,000 years, yet a precise definition of segmentation remains elusive. Here we give the history of the definition of segmentation, followed by a discussion on current controversies in defining a segment. While there is a general consensus that segmentation involves the repetition of units along the anterior-posterior (a-p) axis, long-running debates exist over whether a segment can be composed of only one tissue layer, whether the most anterior region of the arthropod head is considered segmented, and whether and how the vertebrate head is segmented. Additionally, we discuss whether a segment can be composed of a single cell in a column of cells, or a single row of cells within a grid of cells. We suggest that 'segmentation' be used in its more general sense, the repetition of units with a-p polarity along the a-p axis, to prevent artificial classification of animals. We further suggest that this general definition be combined with an exact description of what is being studied, as well as a clearly stated hypothesis concerning the specific nature of the potential homology of structures. These suggestions should facilitate dialogue among scientists who study vastly differing segmental structures.

  17. Paranode Abnormalities and Oxidative Stress in Optic Nerve Vulnerable to Secondary Degeneration: Modulation by 670 nm Light Treatment.

    Directory of Open Access Journals (Sweden)

    Charis R Szymanski

    Full Text Available Secondary degeneration of nerve tissue adjacent to a traumatic injury results in further loss of neurons, glia and function, via mechanisms that may involve oxidative stress. However, changes in indicators of oxidative stress have not yet been demonstrated in oligodendrocytes vulnerable to secondary degeneration in vivo. We show increases in the oxidative stress indicator carboxymethyl lysine at days 1 and 3 after injury in oligodendrocytes vulnerable to secondary degeneration. Dihydroethidium staining for superoxide is reduced, indicating endogenous control of this particular reactive species after injury. Concurrently, node of Ranvier/paranode complexes are altered, with significant lengthening of the paranodal gap and paranode as well as paranode disorganisation. Therapeutic administration of 670 nm light is thought to improve oxidative metabolism via mechanisms that may include increased activity of cytochrome c oxidase. Here, we show that light at 670 nm, delivered for 30 minutes per day, results in in vivo increases in cytochrome c oxidase activity co-localised with oligodendrocytes. Short term (1 day 670 nm light treatment is associated with reductions in reactive species at the injury site. In optic nerve vulnerable to secondary degeneration superoxide in oligodendrocytes is reduced relative to handling controls, and is associated with reduced paranode abnormalities. Long term (3 month administration of 670 nm light preserves retinal ganglion cells vulnerable to secondary degeneration and maintains visual function, as assessed by the optokinetic nystagmus visual reflex. Light at a wavelength of 670 nm may serve as a therapeutic intervention for treatment of secondary degeneration following neurotrauma.

  18. Genetics of frontotemporal lobar degeneration

    Directory of Open Access Journals (Sweden)

    Aswathy P

    2010-10-01

    Full Text Available Frontotemporal lobar degeneration (FTLD is a highly heterogenous group of progressive neurodegenerative disorders characterized by atrophy of prefrontal and anterior temporal cortices. Recently, the research in the field of FTLD has gained increased attention due to the clinical, neuropathological, and genetic heterogeneity and has increased our understanding of the disease pathogenesis. FTLD is a genetically complex disorder. It has a strong genetic basis and 50% of patients show a positive family history for FTLD. Linkage studies have revealed seven chromosomal loci and a number of genes including MAPT, PGRN, VCP, and CHMB-2B are associated with the disease. Neuropathologically, FTLD is classified into tauopathies and ubiquitinopathies. The vast majority of FTLD cases are characterized by pathological accumulation of tau or TDP-43 positive inclusions, each as an outcome of mutations in MAPT or PGRN, respectively. Identification of novel proteins involved in the pathophysiology of the disease, such as progranulin and TDP-43, may prove to be excellent biomarkers of disease progression and thereby lead to the development of better therapeutic options through pharmacogenomics. However, much more dissections into the causative pathways are needed to get a full picture of the etiology. Over the past decade, advances in research on the genetics of FTLD have revealed many pathogenic mutations leading to different clinical manifestations of the disease. This review discusses the current concepts and recent advances in our understanding of the genetics of FTLD.

  19. Automated Segmentation and Retrieval System for CT Head Images

    Science.gov (United States)

    Tong, Hau-Lee; Ahmad Fauzi, Mohammad Faizal; Komiya, Ryoichi

    In this paper, automatic segmentation and retrieval of medical images are presented. For the segmentation, different unsupervised clustering techniques are employed to partition the Computed Tomography (CT) brain images into three regions, which are the abnormalities, cerebrospinal fluids (CSF) and brain matters. The novel segmentation method proposed is a dual level segmentation approach. The first level segmentation, which purpose is to acquire abnormal regions, uses the combination of fuzzy c-means (FCM) and k-means clustering. The second level segmentation performs either the expectation-maximization (EM) technique or the modified FCM with population-diameter independent (PDI) to segment the remaining intracranial area into CSF and brain matters. The system automatically determines which algorithm to be utilized in order to produce optimum results. The retrieval of the medical images is based on keywords such as "no abnormal region", "abnormal region(s) adjacent to the skull" and "abnormal region(s) not adjacent to the skull". Medical data from collaborating hospital are experimented and promising results are observed.

  20. Human habenula segmentation using myelin content.

    Science.gov (United States)

    Kim, Joo-won; Naidich, Thomas P; Ely, Benjamin A; Yacoub, Essa; De Martino, Federico; Fowkes, Mary E; Goodman, Wayne K; Xu, Junqian

    2016-04-15

    The habenula consists of a pair of small epithalamic nuclei located adjacent to the dorsomedial thalamus. Despite increasing interest in imaging the habenula due to its critical role in mediating subcortical reward circuitry, in vivo neuroimaging research targeting the human habenula has been limited by its small size and low anatomical contrast. In this work, we have developed an objective semi-automated habenula segmentation scheme consisting of histogram-based thresholding, region growing, geometric constraints, and partial volume estimation steps. This segmentation scheme was designed around in vivo 3 T myelin-sensitive images, generated by taking the ratio of high-resolution T1w over T2w images. Due to the high myelin content of the habenula, the contrast-to-noise ratio with the thalamus in the in vivo 3T myelin-sensitive images was significantly higher than the T1w or T2w images alone. In addition, in vivo 7 T myelin-sensitive images (T1w over T2*w ratio images) and ex vivo proton density-weighted images, along with histological evidence from the literature, strongly corroborated the in vivo 3 T habenula myelin contrast used in the proposed segmentation scheme. The proposed segmentation scheme represents a step toward a scalable approach for objective segmentation of the habenula suitable for both morphological evaluation and habenula seed region selection in functional and diffusion MRI applications.

  1. Probability of rupture of multiple fault segments

    Science.gov (United States)

    Andrews, D.J.; Schwerer, E.

    2000-01-01

    Fault segments identified from geologic and historic evidence have sometimes been adopted as features limiting the likely extends of earthquake ruptures. There is no doubt that individual segments can sometimes join together to produce larger earthquakes. This work is a trial of an objective method to determine the probability of multisegment ruptures. The frequency of occurrence of events on all conjectured combinations of adjacent segments in northern California is found by fitting to both geologic slip rates and to an assumed distribution of event sizes for the region as a whole. Uncertainty in the shape of the distribution near the maximum magnitude has a large effect on the solution. Frequencies of individual events cannot be determined, but it is possible to find a set of frequencies to fit a model closely. A robust conclusion for the San Francisco Bay region is that large multisegment events occur on the San Andreas and San Gregorio faults, but single-segment events predominate on the extended Hayward and Calaveras strands of segments.

  2. Segmental rigidity and spinal myoclonus as a paraneoplastic syndrome.

    OpenAIRE

    Roobol, T H; Kazzaz, B. A.; Vecht, C. J.

    1987-01-01

    A 68 year old woman is described with persisting muscular rigidity of the left lower leg together with transient myoclonic jerking in the left quadriceps muscle. Six weeks after onset a small cell carcinoma of the lung became manifest. With radiotherapy and chemotherapy complete remission was achieved. Segmental muscular spasm improved at the same time. Necropsy revealed loss and degeneration of alpha-motor neuron cells at one side of the anterior horn of the lumbar enlargement. This case may...

  3. Interactive segmentation for geographic atrophy in retinal fundus images

    OpenAIRE

    Lee, Noah; SMITH, R. THEODORE; Laine, Andrew F.

    2008-01-01

    Fundus auto-fluorescence (FAF) imaging is a non-invasive technique for in vivo ophthalmoscopic inspection of age-related macular degeneration (AMD), the most common cause of blindness in developed countries. Geographic atrophy (GA) is an advanced form of AMD and accounts for 12–21% of severe visual loss in this disorder [3]. Automatic quantification of GA is important for determining disease progression and facilitating clinical diagnosis of AMD. The problem of automatic segmentation of patho...

  4. Kauffman's adjacent possible in word order evolution

    CERN Document Server

    Ferrer-i-Cancho, Ramon

    2015-01-01

    Word order evolution has been hypothesized to be constrained by a word order permutation ring: transitions involving orders that are closer in the permutation ring are more likely. The hypothesis can be seen as a particular case of Kauffman's adjacent possible in word order evolution. Here we consider the problem of the association of the six possible orders of S, V and O to yield a couple of primary alternating orders as a window to word order evolution. We evaluate the suitability of various competing hypotheses to predict one member of the couple from the other with the help of information theoretic model selection. Our ensemble of models includes a six-way model that is based on the word order permutation ring (Kauffman's adjacent possible) and another model based on the dual two-way of standard typology, that reduces word order to basic orders preferences (e.g., a preference for SV over VS and another for SO over OS). Our analysis indicates that the permutation ring yields the best model when favoring pa...

  5. Effects of sagittal endplate shape on lumbar segmental mobility as evaluated by kinetic magnetic resonance imaging.

    Science.gov (United States)

    Li, Yawei; Lord, Elizabeth; Cohen, Yermie; Ruangchainikom, Monchai; Wang, Bing; Lv, Guohua; Wang, Jeffrey C

    2014-08-01

    Retrospective analysis using kinetic magnetic resonance imaging. To investigate relationships between vertebral endplate remodeling, Modic changes, disc degeneration, and lumbar segmental mobility. Previous studies have shown that disc degeneration and vertebral endplate Modic changes are associated with differences in spinal motion, however, the effects of vertebral endplate morphology on lumbar segmental motion have not been fully investigated. A total of 420 patients underwent kinetic magnetic resonance imaging of 2100 lumbar motion segments. Sagittal endplate shapes (concave, flat, irregular), Modic changes (types, 0-3), and disc degeneration (grade, I-V) were assessed along with translational and angular motion of vertebral segments in flexion, extension, and neutral positions. The most common findings were concave endplate shape (63.24%), type 2 Modic change (71.79%), and grade II disc degeneration (40.33%). Flat, irregular endplates were more common at L1-L2, L4-L5, and L5-S1 than L2-L3 and L3-L4. Types 1, 2, and 3 Modic changes increased in frequency according to endplate shape: concave less than flat less than irregular. Type 0 was observed to decrease with the change of endplate shape from flat to concave to irregular. Vertebral levels with irregular endplates had more disc generation than those with flat; levels with flat endplates had significantly more disc degeneration than those with concave. Translational motion of the lumbar segment was greatest at levels with irregular endplates and decreased at those with flat and then concaves endplates. Angular motion was least at levels with irregular endplates and increased at levels with flat, then concave endplates. The degree of pathogenic lumbar segmental motion is associated with remodeling of the sagittal endplate. Endplate remodeling may occur as an adaptation to restrain abnormal movement of the lumbar segment. N/A.

  6. Vitelliform macular degeneration associated with mitochondrial myopathy.

    OpenAIRE

    Modi, G; Heckman, J M; Saffer, D

    1992-01-01

    A patient with mitochondrial myopathy is described. Examination of his fundus revealed bilateral vitelliform degeneration of the maculae. This lesion is a focal abnormality of the retinal pigment epithelium and may be a manifestation of the underlying mitochondrial disease.

  7. Magnetic resonance imaging of intervertebral disc degeneration

    Energy Technology Data Exchange (ETDEWEB)

    Maeda, Hiroshi; Noguchi, Masao (Kitakyushu City Yahata Hospital, Fukuoka (Japan)); Kira, Hideaki; Fujiki, Hiroshi; Shimokawa, Isao; Hinoue, Kaichi

    1993-02-01

    The aim of this study was to correlate the degree of lumbar intervertebral disc degeneration with findings of magnetic resonance imaging (MRI). Seventeen autopsied (from 7 patients) and 21 surgical (from 20 patients) intervertebral discs were used as specimens for histopathological examination. In addition, 21 intervertebral discs were examined on T2-weighted images. Histopathological findings from both autopsied and surgical specimens were well correlated with MRI findings. In particular, T2-weighted images reflected increased collagen fibers and rupture within the fibrous ring accurately. However, when severely degenerated intervertebral discs and hernia protruding the posterior longitudinal ligament existed, histological findings were not concordant well with T2-weighted images. Morphological appearances of autopsy specimens, divided into four on T2-weighted images, were well consistent with histological degeneration. This morphological classification, as shown on T2-weighted images, could also be used in the evaluation of intervertebral disc degeneration. (N.K.).

  8. Degenerate primer design for highly variable genomes.

    Science.gov (United States)

    Li, Kelvin; Shrivastava, Susmita; Stockwell, Timothy B

    2015-01-01

    The application of degenerate PCR primers towards target amplification and sequencing is a useful technique when a population of organisms under investigation is evolving rapidly, or is highly diverse. Degenerate bases in these primers are specified with ambiguity codes that represent alternative nucleotide configurations. Degenerate PCR primers allow the simultaneous amplification of a heterogeneous population by providing a mixture of PCR primers each of which anneal to an alternative genotype found in the isolated sample. However, as the number of degenerate bases specified in a pair of primers rises, the likelihood of amplifying unwanted alternative products also increases. These alternative products may confound downstream data analyses if their levels begin to obfuscate the desired PCR products. This chapter describes a set of computational methodologies that may be used to minimize the degeneracy of designed primers, while still maximizing the proportion of genotypes assayed in the targeted population.

  9. Degenerate second order mean field games systems

    OpenAIRE

    Tonon, Daniela; Cardaliaguet, Pierre; Graber, Philip,; Poretta, Alessio

    2014-01-01

    Parallel session; International audience; We consider degenerate second order mean field games systems with a local coupling. The starting point is the idea that mean field games systems can be understood as an optimality condition for optimal control of PDEs. Developing this strategy for the degenerate second order case, we discuss the existence and uniqueness of a weak solution as well as its stability (vanishing viscosity limit). Speaker: Daniela TONON

  10. The nature of apraxia in corticobasal degeneration.

    OpenAIRE

    Leiguarda, R; Lees, A J; Merello, M; STARKSTEIN, S; Marsden, C D

    1994-01-01

    Although apraxia is one of the most frequent signs in corticobasal degeneration, the phenomenology of this disorder has not been formally examined. Hence 10 patients with corticobasal degeneration were studied with a standardised evaluation for different types of apraxia. To minimise the confounding effects of the primary motor disorder, apraxia was assessed in the least affected limb. Whereas none of the patients showed buccofacial apraxia, seven showed deficits on tests of ideomotor apraxia...

  11. Retinal Cell Degeneration in Animal Models

    OpenAIRE

    Masayuki Niwa; Hitomi Aoki; Akihiro Hirata; Hiroyuki Tomita; Green, Paul G.; Akira Hara

    2016-01-01

    The aim of this review is to provide an overview of various retinal cell degeneration models in animal induced by chemicals (N-methyl-d-aspartate- and CoCl2-induced), autoimmune (experimental autoimmune encephalomyelitis), mechanical stress (optic nerve crush-induced, light-induced) and ischemia (transient retinal ischemia-induced). The target regions, pathology and proposed mechanism of each model are described in a comparative fashion. Animal models of retinal cell degeneration provide insi...

  12. Splitting deformations of degenerations of complex curves towards the classification of atoms of degenerations

    CERN Document Server

    2006-01-01

    The author develops a deformation theory for degenerations of complex curves; specifically, he treats deformations which induce splittings of the singular fiber of a degeneration. He constructs a deformation of the degeneration in such a way that a subdivisor is "barked" (peeled) off from the singular fiber. These "barking deformations" are related to deformations of surface singularities (in particular, cyclic quotient singularities) as well as the mapping class groups of Riemann surfaces (complex curves) via monodromies. Important applications, such as the classification of atomic degenerations, are also explained.

  13. Automated degenerate PCR primer design for high-throughput sequencing improves efficiency of viral sequencing

    Directory of Open Access Journals (Sweden)

    Li Kelvin

    2012-11-01

    Full Text Available Abstract Background In a high-throughput environment, to PCR amplify and sequence a large set of viral isolates from populations that are potentially heterogeneous and continuously evolving, the use of degenerate PCR primers is an important strategy. Degenerate primers allow for the PCR amplification of a wider range of viral isolates with only one set of pre-mixed primers, thus increasing amplification success rates and minimizing the necessity for genome finishing activities. To successfully select a large set of degenerate PCR primers necessary to tile across an entire viral genome and maximize their success, this process is best performed computationally. Results We have developed a fully automated degenerate PCR primer design system that plays a key role in the J. Craig Venter Institute’s (JCVI high-throughput viral sequencing pipeline. A consensus viral genome, or a set of consensus segment sequences in the case of a segmented virus, is specified using IUPAC ambiguity codes in the consensus template sequence to represent the allelic diversity of the target population. PCR primer pairs are then selected computationally to produce a minimal amplicon set capable of tiling across the full length of the specified target region. As part of the tiling process, primer pairs are computationally screened to meet the criteria for successful PCR with one of two described amplification protocols. The actual sequencing success rates for designed primers for measles virus, mumps virus, human parainfluenza virus 1 and 3, human respiratory syncytial virus A and B and human metapneumovirus are described, where >90% of designed primer pairs were able to consistently successfully amplify >75% of the isolates. Conclusions Augmenting our previously developed and published JCVI Primer Design Pipeline, we achieved similarly high sequencing success rates with only minor software modifications. The recommended methodology for the construction of the consensus

  14. Automated degenerate PCR primer design for high-throughput sequencing improves efficiency of viral sequencing.

    Science.gov (United States)

    Li, Kelvin; Shrivastava, Susmita; Brownley, Anushka; Katzel, Dan; Bera, Jayati; Nguyen, Anh Thu; Thovarai, Vishal; Halpin, Rebecca; Stockwell, Timothy B

    2012-11-06

    In a high-throughput environment, to PCR amplify and sequence a large set of viral isolates from populations that are potentially heterogeneous and continuously evolving, the use of degenerate PCR primers is an important strategy. Degenerate primers allow for the PCR amplification of a wider range of viral isolates with only one set of pre-mixed primers, thus increasing amplification success rates and minimizing the necessity for genome finishing activities. To successfully select a large set of degenerate PCR primers necessary to tile across an entire viral genome and maximize their success, this process is best performed computationally. We have developed a fully automated degenerate PCR primer design system that plays a key role in the J. Craig Venter Institute's (JCVI) high-throughput viral sequencing pipeline. A consensus viral genome, or a set of consensus segment sequences in the case of a segmented virus, is specified using IUPAC ambiguity codes in the consensus template sequence to represent the allelic diversity of the target population. PCR primer pairs are then selected computationally to produce a minimal amplicon set capable of tiling across the full length of the specified target region. As part of the tiling process, primer pairs are computationally screened to meet the criteria for successful PCR with one of two described amplification protocols. The actual sequencing success rates for designed primers for measles virus, mumps virus, human parainfluenza virus 1 and 3, human respiratory syncytial virus A and B and human metapneumovirus are described, where >90% of designed primer pairs were able to consistently successfully amplify >75% of the isolates. Augmenting our previously developed and published JCVI Primer Design Pipeline, we achieved similarly high sequencing success rates with only minor software modifications. The recommended methodology for the construction of the consensus sequence that encapsulates the allelic variation of the targeted

  15. Detecting Adjacent Relativity of Engineering Drawing Entities with Container Window

    Institute of Scientific and Technical Information of China (English)

    林福严; 邱友申; 秦吉胜

    2001-01-01

    Automatic recognition and interpretation of engineering drawing plays an important role in computer aided engineering. Detecting the positional relation between entities is an important topic in this research field. In this paper the concepts of adjacent relativity and container window of drawing entities were proposed. By means of container window, the adjacent irrelative entities can be detected quickly and effectively, which speeds up the process of adjacent relativity detection. Meanwhile, the algorithm of adjacent relativity detection was discussed.

  16. Keypoint Transfer Segmentation

    OpenAIRE

    Wachinger, C.; Toews, M.; Langs, G.; Wells, W.; Golland, P.

    2015-01-01

    We present an image segmentation method that transfers label maps of entire organs from the training images to the novel image to be segmented. The transfer is based on sparse correspondences between keypoints that represent automatically identified distinctive image locations. Our segmentation algorithm consists of three steps: (i) keypoint matching, (ii) voting-based keypoint labeling, and (iii) keypoint-based probabilistic transfer of organ label maps. We introduce generative models for th...

  17. Exchange coupling between laterally adjacent nanomagnets

    Science.gov (United States)

    Dey, H.; Csaba, G.; Bernstein, G. H.; Porod, W.

    2016-09-01

    We experimentally demonstrate exchange-coupling between laterally adjacent nanomagnets. Our results show that two neighboring nanomagnets that are each antiferromagnetically exchange-coupled to a common ferromagnetic bottom layer can be brought into strong ferromagnetic interaction. Simulations show that interlayer exchange coupling effectively promotes ferromagnetic alignment between the two nanomagnets, as opposed to antiferromagnetic alignment due to dipole-coupling. In order to experimentally demonstrate the proposed scheme, we fabricated arrays of pairs of elongated, single-domain nanomagnets. Magnetic force microscopy measurements show that most of the pairs are ferromagnetically ordered. The results are in agreement with micromagnetic simulations. The presented scheme can achieve coupling strengths that are significantly stronger than dipole coupling, potentially enabling far-reaching applications in Nanomagnet Logic, spin-wave devices and three-dimensional storage and computing.

  18. Biomechanical changes of the lumbar segment after total disc replacement : charite(r), prodisc(r) and maverick(r) using finite element model study.

    Science.gov (United States)

    Kim, Ki-Tack; Lee, Sang-Hun; Suk, Kyung-Soo; Lee, Jung-Hee; Jeong, Bi-O

    2010-06-01

    The purpose of this study was to analyze the biomechanical effects of three different constrained types of an artificial disc on the implanted and adjacent segments in the lumbar spine using a finite element model (FEM). The created intact model was validated by comparing the flexion-extension response without pre-load with the corresponding results obtained from the published experimental studies. The validated intact lumbar model was tested after implantation of three artificial discs at L4-5. Each implanted model was subjected to a combination of 400 N follower load and 5 Nm of flexion/extension moments. ABAQUS version 6.5 (ABAQUS Inc., Providence, RI, USA) and FEMAP version 8.20 (Electronic Data Systems Corp., Plano, TX, USA) were used for meshing and analysis of geometry of the intact and implanted models. Under the flexion load, the intersegmental rotation angles of all the implanted models were similar to that of the intact model, but under the extension load, the values were greater than that of the intact model. The facet contact loads of three implanted models were greater than the loads observed with the intact model. Under the flexion load, three types of the implanted model at the L4-5 level showed the intersegmental rotation angle similar to the one measured with the intact model. Under the extension load, all of the artificial disc implanted models demonstrated an increased extension rotational angle at the operated level (L4-5), resulting in an increase under the facet contact load when compared with the adjacent segments. The increased facet load may lead to facet degeneration.

  19. Biomechanical Changes of the Lumbar Segment after Total Disc Replacement : Charite®, Prodisc® and Maverick® Using Finite Element Model Study

    Science.gov (United States)

    Kim, Ki-Tack; Lee, Sang-Hun; Suk, Kyung-Soo; Lee, Jung-Hee

    2010-01-01

    Objective The purpose of this study was to analyze the biomechanical effects of three different constrained types of an artificial disc on the implanted and adjacent segments in the lumbar spine using a finite element model (FEM). Methods The created intact model was validated by comparing the flexion-extension response without pre-load with the corresponding results obtained from the published experimental studies. The validated intact lumbar model was tested after implantation of three artificial discs at L4-5. Each implanted model was subjected to a combination of 400 N follower load and 5 Nm of flexion/extension moments. ABAQUS™ version 6.5 (ABAQUS Inc., Providence, RI, USA) and FEMAP version 8.20 (Electronic Data Systems Corp., Plano, TX, USA) were used for meshing and analysis of geometry of the intact and implanted models. Results Under the flexion load, the intersegmental rotation angles of all the implanted models were similar to that of the intact model, but under the extension load, the values were greater than that of the intact model. The facet contact loads of three implanted models were greater than the loads observed with the intact model. Conclusion Under the flexion load, three types of the implanted model at the L4-5 level showed the intersegmental rotation angle similar to the one measured with the intact model. Under the extension load, all of the artificial disc implanted models demonstrated an increased extension rotational angle at the operated level (L4-5), resulting in an increase under the facet contact load when compared with the adjacent segments. The increased facet load may lead to facet degeneration. PMID:20617091

  20. Universal Numeric Segmented Display

    CERN Document Server

    Azad, Md Abul kalam; Kamruzzaman, S M

    2010-01-01

    Segmentation display plays a vital role to display numerals. But in today's world matrix display is also used in displaying numerals. Because numerals has lots of curve edges which is better supported by matrix display. But as matrix display is costly and complex to implement and also needs more memory, segment display is generally used to display numerals. But as there is yet no proposed compact display architecture to display multiple language numerals at a time, this paper proposes uniform display architecture to display multiple language digits and general mathematical expressions with higher accuracy and simplicity by using a 18-segment display, which is an improvement over the 16 segment display.

  1. Fully automatic segmentation of complex organ systems: example of trachea, esophagus and heart segmentation in CT images

    Science.gov (United States)

    Meyer, Carsten; Peters, Jochen; Weese, Jürgen

    2011-03-01

    Automatic segmentation is a prerequisite to efficiently analyze the large amount of image data produced by modern imaging modalities. Many algorithms exist to segment individual organs or organ systems. However, new clinical applications and the progress in imaging technology will require the segmentation of more and more complex organ systems composed of a number of substructures, e.g., the heart, the trachea, and the esophagus. The goal of this work is to demonstrate that such complex organ systems can be successfully segmented by integrating the individual organs into a general model-based segmentation framework, without tailoring the core adaptation engine to the individual organs. As an example, we address the fully automatic segmentation of the trachea (around its main bifurcation, including the proximal part of the two main bronchi) and the esophagus in addition to the heart with all chambers and attached major vessels. To this end, we integrate the trachea and the esophagus into a model-based cardiac segmentation framework. Specifically, in a first parametric adaptation step of the segmentation workflow, the trachea and the esophagus share global model transformations with adjacent heart structures. This allows to obtain a robust, approximate segmentation for the trachea even if it is only partly inside the field-of-view, and for the esophagus in spite of limited contrast. The segmentation is then refined in a subsequent deformable adaptation step. We obtained a mean segmentation error of about 0.6mm for the trachea and 2.3mm for the esophagus on a database of 23 volumetric cardiovascular CT images. Furthermore, we show by quantitative evaluation that our integrated framework outperforms individual esophagus segmentation, and individual trachea segmentation if the trachea is only partly inside the field-of-view.

  2. Outcomes and radiographs changes of lumbar degeneration disease treated by dynamic stabilization device%非融合固定技术治疗腰椎退行性疾病的临床疗效和影像学分析

    Institute of Scientific and Technical Information of China (English)

    张乐辉; 王炳强; 李东; 李锦军; 苏楠; 杨雍

    2010-01-01

    目的 探讨一种非融合固定技术--腰椎棘突间动态稳定系统(简称Wallis系统)治疗腰椎退行性疾病的临床疗效和影像学分析.方法 2008年2月-2010年1月因腰椎间盘突出症、腰椎管狭窄症行腰椎后路Wallis固定术,通过随访进行分析研究.结果 随访患者平均住院时间23.59 d,手术时间3.00 h,出血量平均225.56 mL,术前JOA评分13.93分;随访时26.69分,二者有显著性差异.术后改善率83.7%.患者腰椎前凸保持良好,术前病变节段腰椎活动度平均5.22°,随访时平均2.44°,二者有显著性差异.术前病变节段后伸平均3.32°,术后随访时平均1.39°,二者有显著性差异.Wallis植入后病变节段上一位节段术前平均活动度为3.68°,术后随访时6.54°,二者有显著性差异.术前后伸平均1.95°,随访时平均后伸3.95°,二者有显著差异.结论 腰椎后路减压+Wallis非融合固定术治疗腰椎退行性疾病手术安全,术后疗效肯定.术后病变节段活动度减少,特别是后伸活动限制更明显,前屈则无明显限制.术后上一位临近节段活动代偿增加,后伸增加更显著.%Objective To observe the clinical therapeutic outcomes and the radiographs changes of lumbar degeneration disease treated by dynamic stabilization device (Wallis). Methods Eighty-four cases of lumbar degeneration disease were treated by threaded fusion cage, from May 1997 to May 2002. The JOA scores, the rate of fusion,cage sink and adjacent segment degeneration were observed. Results The average hospitalizotion was 23.59 days. The mean operation time was 3.00 hours. The mean JOA scores were 13.93 before the operation,while 26.69 on the end of the following time respectively; there was statistical significant. The mean motion of operative segment was 5.22 before operation, while 2.44 on the end of the following time respectively. The mean extension of operative segment was 3.32 before operation ,while 1.39 on the end of the following

  3. Heterogeneous Chromosomal Aberrations in Intraductal Breast Lesions Adjacent to Invasive Carcinoma

    Directory of Open Access Journals (Sweden)

    Michaela Aubele

    2000-01-01

    Full Text Available There is evidence that breast cancer is a heterogeneous disease phenotypically as well as molecular biologically. So far, heterogeneity on the molecular biological level has not been investigated in potential precursor lesions, such as ductal hyperplasia (DH and ductal carcinoma in situ (DCIS. In this study we applied comparative genomic hybridization (CGH to formalin‐fixed, paraffin‐embedded breast tissue with DH and DCIS, adjacent to invasive ductal carcinoma (IDC, to screen these potential precursor lesions for whole genomic chromosomal imbalances. Laser‐microdissection was used to select pure cell populations from the sections. Isolated DNA was amplified by degenerate oligonucleotide primed PCR (DOP‐PCR and further processed for CGH analysis.

  4. From interpretation to segmentation

    NARCIS (Netherlands)

    Koning, A.R.; Lier, R.J. van

    2005-01-01

    In visual perception, part segmentation of an object is considered to be guided by image-based properties, such as occurrences of deep concavities in the outer contour. However, object-based properties can also provide information regarding segmentation. In this study, outer contours and interpretat

  5. Segmentation, advertising and prices

    NARCIS (Netherlands)

    Galeotti, Andrea; Moraga González, José

    This paper explores the implications of market segmentation on firm competitiveness. In contrast to earlier work, here market segmentation is minimal in the sense that it is based on consumer attributes that are completely unrelated to tastes. We show that when the market is comprised by two

  6. Segmentation, advertising and prices

    NARCIS (Netherlands)

    Galeotti, Andrea; Moraga González, José

    2008-01-01

    This paper explores the implications of market segmentation on firm competitiveness. In contrast to earlier work, here market segmentation is minimal in the sense that it is based on consumer attributes that are completely unrelated to tastes. We show that when the market is comprised by two consume

  7. Benign segmental bronchial obstruction

    Energy Technology Data Exchange (ETDEWEB)

    Loercher, U.

    1988-09-01

    The benigne segmental bronchial obstruction - mostly discovered on routine chest films - can well be diagnosed by CT. The specific findings in CT are the site of the bronchial obstruction, the mucocele and the localized empysema of the involved segment. Furthermore CT allows a better approach to the underlying process.

  8. Hospital benefit segmentation.

    Science.gov (United States)

    Finn, D W; Lamb, C W

    1986-12-01

    Market segmentation is an important topic to both health care practitioners and researchers. The authors explore the relative importance that health care consumers attach to various benefits available in a major metropolitan area hospital. The purposes of the study are to test, and provide data to illustrate, the efficacy of one approach to hospital benefit segmentation analysis.

  9. Prospectives for gene therapy of retinal degenerations.

    Science.gov (United States)

    Thumann, Gabriele

    2012-08-01

    Retinal degenerations encompass a large number of diseases in which the retina and associated retinal pigment epithelial (RPE) cells progressively degenerate leading to severe visual disorders or blindness. Retinal degenerations can be divided into two groups, a group in which the defect has been linked to a specific gene and a second group that has a complex etiology that includes environmental and genetic influences. The first group encompasses a number of relatively rare diseases with the most prevalent being Retinitis pigmentosa that affects approximately 1 million individuals worldwide. Attempts have been made to correct the defective gene by transfecting the appropriate cells with the wild-type gene and while these attempts have been successful in animal models, human gene therapy for these inherited retinal degenerations has only begun recently and the results are promising. To the second group belong glaucoma, age-related macular degeneration (AMD) and diabetic retinopathy (DR). These retinal degenerations have a genetic component since they occur more often in families with affected probands but they are also linked to environmental factors, specifically elevated intraocular pressure, age and high blood sugar levels respectively. The economic and medical impact of these three diseases can be assessed by the number of individuals affected; AMD affects over 30 million, DR over 40 million and glaucoma over 65 million individuals worldwide. The basic defect in these diseases appears to be the relative lack of a neurogenic environment; the neovascularization that often accompanies these diseases has suggested that a decrease in pigment epithelium-derived factor (PEDF), at least in part, may be responsible for the neurodegeneration since PEDF is not only an effective neurogenic and neuroprotective agent but also a potent inhibitor of neovascularization. In the last few years inhibitors of vascularization, especially antibodies against vascular endothelial cell

  10. Optic pathway degeneration in Japanese black cattle.

    Science.gov (United States)

    Chiba, Shiori; Funato, Shingo; Horiuchi, Noriyuki; Matsumoto, Kotaro; Inokuma, Hisashi; Furuoka, Hidefumi; Kobayashi, Yoshiyasu

    2015-02-01

    Degeneration of the optic pathway has been reported in various animal species including cattle. We experienced a case of bilateral optic tract degeneration characterized by severe gliosis in a Japanese black cattle without any obvious visual defects. To evaluate the significance, pathological nature and pathogenesis of the lesions, we examined the optic pathway in 60 cattle (41 Japanese black, 13 Holstein and 6 crossbreed) with or without ocular abnormalities. None of these animals had optic canal stenosis. Degenerative changes with severe gliosis in the optic pathway, which includes the optic nerve, optic chiasm and optic tract, were only observed in 8 Japanese black cattle with or without ocular abnormalities. Furthermore, strong immunoreactivity of glial fibrillary acidic protein was observed in the retinal stratum opticum and ganglion cell layer in all 5 cattle in which the optic pathway lesions could be examined. As etiological research, we also examined whether the concentrations of vitamin A and vitamin B12 or bovine viral diarrhea virus (BVDV) infection was associated with optic pathway degeneration. However, our results suggested that the observed optic pathway degeneration was probably not caused by these factors. These facts indicate the presence of optic pathway degeneration characterized by severe gliosis that has never been reported in cattle without bilateral compressive lesions in the optic pathway or bilateral severe retinal atrophy.

  11. Short term outcome of posterior dynamic stabilization system in degenerative lumbar diseases

    Directory of Open Access Journals (Sweden)

    Mingyuan Yang

    2014-01-01

    Conclusion: Dynamic stabilization system treating lumbar degenerative disease showed clinical benefits with motion preservation of the operated segments, but does not have the significant advantage on motion preservation at adjacent segments, to avoid the degeneration of adjacent intervertebral disk.

  12. Non-fusion segment disease after the anterior cervical arthrodesis:a retrospective study%颈椎前路融合术后非融合节段退变性疾病的回顾性研究

    Institute of Scientific and Technical Information of China (English)

    郭炳路; 宋科冉; 陈巧灵; 陈增海; 王大鹏; 王慧; 金培; 唐家广

    2016-01-01

    Objective To investigate the incidence and causes of non-fusion segment disease ( NFSD ), both adjacent and non-adjacent to the fused segment, after the anterior cervical arthrodesis.Methods This is a retrospective cohort study. Between January 1998 and January 2011, 171 patients who had anterior cervical decompression and fusion for the intervertebral disc herniation and cervical spondylosis were followed clinically. There were 97 males and 74 females, and the average age at the operation was ( 51.90 ± 9.28 ) years ( range: 31 - 72 years ). We evaluated the correlation between the incidence of symptomatic non-fusion segment disease and the following clinical parameters ( age at the operation, fusion levels ) and radiological parameters ( preoperative and postoperative cervical spine alignment, Pavlov’s ratio at the C5 level, and preoperative existence of a non-fusion segment degeneration on magnetic resonance imaging ).Results Of the 171 patients reviewed, 16 patients had non-fusion segment disease ( 9.36% ), 12 patients had adjacent segment disease and 4 had non-adjacent segment disease. Postoperative cervical lordosis in the non-fusion segment disease group was signiifcantly smaller than that of the disease-free group [ ( 7.38 ± 12.37 ) ° vs. ( 17.26 ± 9.75 ) °,P < 0.001 ]. Fusion levels in the NFSD group were 1.63 whereas 2.27 in disease-free group (P = 0.002 ). The incidence of disc degeneration in non-fused segments was more severe in the NFSD group than in the disease-free group [ ( 2.63 ± 0.62 )vs. ( 1.62 ± 0.99 ), P = 0.008 ].Conclusions The incidence of symptomatic non-fusion segment disease after the anterior cervical arthrodesis has multifactorial causes. Postoperative cervical lordosis, disc degeneration in non-fusion segments, and the number of fusion levels are all factors in the incidence of NFSD.%目的:探讨颈椎前路减压融合术后非融合节段病变( non-fusion segment disease,NFSD )的发生率和

  13. Interaction between Adjacent Lightning Discharges in Clouds

    Institute of Scientific and Technical Information of China (English)

    WANG Yanhui; ZHANG Guangshu; ZHANG Tong; LI Yajun; WU Bin; ZHANG Tinglong

    2013-01-01

    Using a 3D lightning radiation source locating system (LLS),three pairs of associated lightning discharges (two or more adjacent lightning discharges following an arbitrary rule that their space-gap was less than 10 km and their time-gap was less than 800 ms) were observed,and the interaction between associated lightning discharges was analyzed.All these three pairs of associated lightning discharges were found to involve three or more charge regions (the ground was considered as a special charge region).Moreover,at least one charge region involved two lightning discharges per pair of associated lightning discharges.Identified from electric field changes,the subsequent lightning discharges were suppressed by the prior lightning discharges.However,it is possible that the prior lightning discharge provided a remaining discharge channel to facilitate the subsequent lightning discharge.The third case provided evidence of this possibility.Together,the results suggested that,if the charges in the main negative charge region can be consumed using artificial lightning above the main negative charge regions,lightning accidents on the ground could be greatly reduced,on the condition that the height of the main negative charge region and the charge intensity of the lower positive charge region are suitable.

  14. Potential role of retinal pigment epithelial lipofuscin accumulation in age-related macular degeneration.

    Science.gov (United States)

    Katz, Martin L

    2002-01-01

    Age-related macular degeneration (AMD) is a leading cause of severe visual impairment in developed countries. The vision loss associated with AMD is the result of degenerative changes in the central region of the retina called the macula. Maintenance of normal structure and function of the macular retina, and of the remainder of the retina as well, is critically dependent on the supporting role of the adjacent retinal pigment epithelium (RPE). Impairment of normal RPE functions is known to result in retinal degeneration and loss of visual function. Thus, it has been hypothesized that the retinal degeneration that characterizes AMD is secondary to age-related deterioration in RPE support functions. Like many other postmitotic cell types, the RPE accumulates autofluorescent lysosomal storage bodies (lipofuscin) during senescence. In human eyes, lipofuscin comes to occupy a substantial fraction of the RPE cytoplasmic volume in the elderly. Does this lipofuscin accumulation contribute to the development of AMD? This question is a specific case of the broader question of whether lipofuscin accumulation in general is detrimental to cells. Unfortunately, definitive data do not exist to allow these questions to be answered. Although a correlation between RPE lipofuscin content and AMD has been reported, a cause-and-effect relationship between RPE lipofuscin accumulation and the development of this disease has not been established. It has been reported that a mutation in a gene encoding a photoreceptor-specific protein results in massive RPE lipofuscin accumulation and early-onset macular degeneration. However, again the accelerated RPE lipofuscin accumulation has not been shown to be the cause of the accompanying macular degeneration. The lack of a definitive link between RPE lipofuscin accumulation and AMD illustrates one of the biggest challenges remaining in lipofuscin research-determining whether lipofuscin accumulation per se has an impact on cell function.

  15. Transient forebrain ischemia-induced neuronal degeneration in fascia dentata transplants.

    Science.gov (United States)

    Tønder, N; Aznar, S; Johansen, F F

    1994-01-01

    Fascia dentata tissue blocks from newborn rats were grafted into one-week-old, ibotenic acid-induced lesions of the fascia dentata, or the normal fascia dentata of adult rats. After at least 2 months survival the recipient rats were subjected to 10 min of forebrain ischemia (4-vessel occlusion), and examined 2 or 4 days later for neuronal degeneration in the host hippocampi and the transplants, by silver staining and immunohistochemistry. Transplants survived well in both normal and lesioned host brains, with easily recognizable subfields and layers and presence of normal types of principal and non-principal neurons. As expected, argyrophilic, degenerating neurons were present in the pyramidal cell layer of CAl and CA3c of the non-grafted contralateral host hippocampus and in the contralateral dentate hilus (CA4). In the hilus the degeneration corresponded to the loss of somatostatin-immunoreactive neurons, while parvalbumin-immunoreactive neurons were spared. In the dentate transplants degenerating neurons were observed in the granule cell layer, the hilus and the adjacent CA3 pyramidal cell layer. There was no obvious loss of either somatostatin- or parvalbumin-immunoreactive neurons. The degeneration varied considerably between transplants, from a few to large groups of silver stained neurons, but this difference did not display any obvious relation to grafting into normal or lesioned hosts, the exact location of the grafts or the general organization and distribution of intrinsic or extrinsic host afferents in the grafts. The results demonstrate that both ischemia-susceptible and -resistant types of neurons grafted to normal and lesioned adult rat brains are susceptible to transient forebrain ischemia after transplantation. In spite of an extensive reorganization of transplant nerve connections, the physiologicalbiochemical mechanisms necessary for the induction of ischemic cell death were accordingly present in the transplants.

  16. Phase space methods for degenerate quantum gases

    CERN Document Server

    Dalton, Bryan J; Barnett, Stephen M

    2015-01-01

    Recent experimental progress has enabled cold atomic gases to be studied at nano-kelvin temperatures, creating new states of matter where quantum degeneracy occurs - Bose-Einstein condensates and degenerate Fermi gases. Such quantum states are of macroscopic dimensions. This book presents the phase space theory approach for treating the physics of degenerate quantum gases, an approach already widely used in quantum optics. However, degenerate quantum gases involve massive bosonic and fermionic atoms, not massless photons. The book begins with a review of Fock states for systems of identical atoms, where large numbers of atoms occupy the various single particle states or modes. First, separate modes are considered, and here the quantum density operator is represented by a phase space distribution function of phase space variables which replace mode annihilation, creation operators, the dynamical equation for the density operator determines a Fokker-Planck equation for the distribution function, and measurable...

  17. The cell stress machinery and retinal degeneration.

    Science.gov (United States)

    Athanasiou, Dimitra; Aguilà, Monica; Bevilacqua, Dalila; Novoselov, Sergey S; Parfitt, David A; Cheetham, Michael E

    2013-06-27

    Retinal degenerations are a group of clinically and genetically heterogeneous disorders characterised by progressive loss of vision due to neurodegeneration. The retina is a highly specialised tissue with a unique architecture and maintaining homeostasis in all the different retinal cell types is crucial for healthy vision. The retina can be exposed to a variety of environmental insults and stress, including light-induced damage, oxidative stress and inherited mutations that can lead to protein misfolding. Within retinal cells there are different mechanisms to cope with disturbances in proteostasis, such as the heat shock response, the unfolded protein response and autophagy. In this review, we discuss the multiple responses of the retina to different types of stress involved in retinal degenerations, such as retinitis pigmentosa, age-related macular degeneration and glaucoma. Understanding the mechanisms that maintain and re-establish proteostasis in the retina is important for developing new therapeutic approaches to fight blindness.

  18. Families and degenerations of conformal field theories

    Energy Technology Data Exchange (ETDEWEB)

    Roggenkamp, D.

    2004-09-01

    In this work, moduli spaces of conformal field theories are investigated. In the first part, moduli spaces corresponding to current-current deformation of conformal field theories are constructed explicitly. For WZW models, they are described in detail, and sigma model realizations of the deformed WZW models are presented. The second part is devoted to the study of boundaries of moduli spaces of conformal field theories. For this purpose a notion of convergence of families of conformal field theories is introduced, which admits certain degenerated conformal field theories to occur as limits. To such a degeneration of conformal field theories, a degeneration of metric spaces together with additional geometric structures can be associated, which give rise to a geometric interpretation. Boundaries of moduli spaces of toroidal conformal field theories, orbifolds thereof and WZW models are analyzed. Furthermore, also the limit of the discrete family of Virasoro minimal models is investigated. (orig.)

  19. STUDY ON VARIATIONS OF INFERIOR SEGMENTAL BRANCH OF RENAL ARTERY

    Directory of Open Access Journals (Sweden)

    Chandragirish S

    2014-11-01

    Full Text Available Background: The segmental arteries of the kidney supply the organ in such a way that, each renal pole receives its own artery while, the anterior portion between the poles is supplied by an upper and lower segmental vessel. These two arteries also include in their territory the lateral edge of the kidney and adjacent to the strip of parenchyma on the dorsal or posterior aspect of the organ. The knowledge of inferior segmental branch of renal artery is very important for surgeries in its distribution area in kidney. Materials and Methods: 100 kidneys (Fifty pairs intact with abdominal aorta were collected from department of Forensic medicine, JSS Medical College and Mysore Medical College. For study of segmental variation Corrosion cast technique method was used. The variations of inferior segmental branch of renal artery were observed and recorded. Results: In present study type I inferior segmental branch of renal artery were found in - 59% cases, type II in - 6% cases, type III in - 28% cases, type IV in - 2% cases. Conclusion: The inferior segmental artery from the anterior division of the renal artery is the commonest event –arising in 59%. This is Type I, the normal type. It arises from the renal artery (28% or from the posterior division (6% or from the aorta (2%. The knowledge of inferior segmental branch of renal artery helpful in kidney transplantation and renal surgery because these type of surgeries success mainly depends on arterial ligations.

  20. Late Permian to Triassic intraplate orogeny of the southern Tianshan and adjacent regions, NW China

    Institute of Scientific and Technical Information of China (English)

    Wei Ju; Guiting Hou

    2014-01-01

    The South Tianshan Orogen and adjacent regions of Central Asia are located in the southwestern part of the Central Asian Orogenic Belt. The formation of South Tianshan Orogen was a diachronous, scissors-like process, which took place during the Palaeozoic, and its western segment was accepted as a site of the final collision between the Tarim Craton and the North Asian continent, which occurred in the late Palaeozoic. However, the post-collisional tectonic evolution of the South Tianshan Orogen and adjacent regions remains debatable. Based on previous studies and recent geochronogical data, we suggest that the final collision between the Tarim Craton and the North Asian continent occurred during the late Carboniferous. Therefore, the Permian was a period of intracontinental environment in the southern Tianshan and adjacent regions. We propose that an earlier, small-scale intraplate orogenic stage occurred in late Permian to Triassic time, which was the first intraplate process in the South Tianshan Orogen and adjacent regions. The later large-scale and well-known Neogene to Quaternary intraplate orogeny was induced by the collision between the India subcontinent and the Eurasian plate. The paper presents a new evolutionary model for the South Tianshan Orogen and adjacent regions, which includes seven stages: (I) late Ordovicianeearly Silurian opening of the South Tianshan Ocean;(II) middle Silurianemiddle Devonian subduction of the South Tianshan Ocean beneath an active margin of the North Asian continent; (III) late Devonianelate Carboniferous closure of the South Tianshan Ocean and collision between the Kazakhstan-Yili and Tarim continental blocks;(IV) early Permian post-collisional magmatism and rifting;(V) late PermianeTriassic the first intraplate orogeny;(VI) JurassicePalaeogene tectonic stagnation and (VII) NeoceneeQuaternary intraplate orogeny.

  1. Keypoint Transfer Segmentation.

    Science.gov (United States)

    Wachinger, C; Toews, M; Langs, G; Wells, W; Golland, P

    2015-01-01

    We present an image segmentation method that transfers label maps of entire organs from the training images to the novel image to be segmented. The transfer is based on sparse correspondences between keypoints that represent automatically identified distinctive image locations. Our segmentation algorithm consists of three steps: (i) keypoint matching, (ii) voting-based keypoint labeling, and (iii) keypoint-based probabilistic transfer of organ label maps. We introduce generative models for the inference of keypoint labels and for image segmentation, where keypoint matches are treated as a latent random variable and are marginalized out as part of the algorithm. We report segmentation results for abdominal organs in whole-body CT and in contrast-enhanced CT images. The accuracy of our method compares favorably to common multi-atlas segmentation while offering a speed-up of about three orders of magnitude. Furthermore, keypoint transfer requires no training phase or registration to an atlas. The algorithm's robustness enables the segmentation of scans with highly variable field-of-view.

  2. Pancreas and cyst segmentation

    Science.gov (United States)

    Dmitriev, Konstantin; Gutenko, Ievgeniia; Nadeem, Saad; Kaufman, Arie

    2016-03-01

    Accurate segmentation of abdominal organs from medical images is an essential part of surgical planning and computer-aided disease diagnosis. Many existing algorithms are specialized for the segmentation of healthy organs. Cystic pancreas segmentation is especially challenging due to its low contrast boundaries, variability in shape, location and the stage of the pancreatic cancer. We present a semi-automatic segmentation algorithm for pancreata with cysts. In contrast to existing automatic segmentation approaches for healthy pancreas segmentation which are amenable to atlas/statistical shape approaches, a pancreas with cysts can have even higher variability with respect to the shape of the pancreas due to the size and shape of the cyst(s). Hence, fine results are better attained with semi-automatic steerable approaches. We use a novel combination of random walker and region growing approaches to delineate the boundaries of the pancreas and cysts with respective best Dice coefficients of 85.1% and 86.7%, and respective best volumetric overlap errors of 26.0% and 23.5%. Results show that the proposed algorithm for pancreas and pancreatic cyst segmentation is accurate and stable.

  3. [New aspects in age related macular degeneration].

    Science.gov (United States)

    Turlea, C

    2012-01-01

    Being the leading cause of blindness in modern world Age Related Macular Degeneration has beneficiated in the last decade of important progress in diagnosis, classification and the discovery of diverse factors who contribute to the etiology of this disease. Treatments have arised who can postpone the irreversible evolution of the disease and thus preserve vision. Recent findings have identified predisposing genetic factors and also inflamatory and imunological parameters that can be modified trough a good and adequate prevention and therapy This articole reviews new aspects of patology of Age Related Macular Degeneration like the role of complement in maintaining inflamation and the role of oxidative stress on different structures of the retina.

  4. Intracavity frequency-doubled degenerate laser

    CERN Document Server

    Liew, Seng Fatt; Weiler, Sascha; Monjardin-Lopez, Jesus Fernando; Ramme, Mark; Redding, Brandon; Choma, Michael A; Cao, Hui

    2016-01-01

    We develop a green light source with low spatial coherence via intracavity frequency doubling of a solid-state degenerate laser. The second harmonic emission supports many more transverse modes than the fundamental emission, and exhibit lower spatial coherence. A strong suppression of speckle formation is demonstrated for both fundamental and second harmonic beams. Using the green emission for fluorescence excitation, we show the coherent artifacts are removed from the full-field fluorescence images. The high power, low spatial coherence and good directionality makes the green degenerate laser an attractive illumination source for parallel imaging and projection display.

  5. Segmentation of consumer's markets and evaluation of market's segments

    OpenAIRE

    ŠVECOVÁ, Iveta

    2013-01-01

    The goal of this bachelor thesis was to explain a possibly segmentation of consumer´s markets for a chosen company, and to present a suitable goods offer, so it would be suitable to the needs of selected segments. The work is divided into theoretical and practical part. First part describes marketing, segmentation, segmentation of consumer's markets, consumer's market, market's segments a other terms. Second part describes an evaluation of questionnaire survey, discovering of market's segment...

  6. 670-nm light treatment reduces complement propagation following retinal degeneration

    Directory of Open Access Journals (Sweden)

    Rutar Matt

    2012-11-01

    Full Text Available Abstract Aim Complement activation is associated with the pathogenesis of age-related macular degeneration (AMD. We aimed to investigate whether 670-nm light treatment reduces the propagation of complement in a light-induced model of atrophic AMD. Methods Sprague–Dawley (SD rats were pretreated with 9 J/cm2 670-nm light for 3 minutes daily over 5 days; other animals were sham treated. Animals were exposed to white light (1,000 lux for 24 h, after which animals were kept in dim light (5 lux for 7 days. Expression of complement genes was assessed by quantitative polymerase chain reaction (qPCR, and immunohistochemistry. Counts were made of C3-expressing monocytes/microglia using in situ hybridization. Photoreceptor death was also assessed using outer nuclear layer (ONL thickness measurements, and oxidative stress using immunohistochemistry for 4-hydroxynonenal (4-HNE. Results Following light damage, retinas pretreated with 670-nm light had reduced immunoreactivity for the oxidative damage maker 4-HNE in the ONL and outer segments, compared to controls. In conjunction, there was significant reduction in retinal expression of complement genes C1s, C2, C3, C4b, C3aR1, and C5r1 following 670 nm treatment. In situ hybridization, coupled with immunoreactivity for the marker ionized calcium binding adaptor molecule 1 (IBA1, revealed that C3 is expressed by infiltrating microglia/monocytes in subretinal space following light damage, which were significantly reduced in number after 670 nm treatment. Additionally, immunohistochemistry for C3 revealed a decrease in C3 deposition in the ONL following 670 nm treatment. Conclusions Our data indicate that 670-nm light pretreatment reduces lipid peroxidation and complement propagation in the degenerating retina. These findings have relevance to the cellular events of complement activation underling the pathogenesis of AMD, and highlight the potential of 670-nm light as a non-invasive anti-inflammatory therapy.

  7. Classification of wet aged related macular degeneration using optical coherence tomographic images

    Science.gov (United States)

    Haq, Anam; Mir, Fouwad Jamil; Yasin, Ubaid Ullah; Khan, Shoab A.

    2013-12-01

    Wet Age related macular degeneration (AMD) is a type of age related macular degeneration. In order to detect Wet AMD we look for Pigment Epithelium detachment (PED) and fluid filled region caused by choroidal neovascularization (CNV). This form of AMD can cause vision loss if not treated in time. In this article we have proposed an automated system for detection of Wet AMD in Optical coherence tomographic (OCT) images. The proposed system extracts PED and CNV from OCT images using segmentation and morphological operations and then detailed feature set are extracted. These features are then passed on to the classifier for classification. Finally performance measures like accuracy, sensitivity and specificity are calculated and the classifier delivering the maximum performance is selected as a comparison measure. Our system gives higher performance using SVM as compared to other methods.

  8. Role of calpains in the injury-induced dysfunction and degeneration of the mammalian axon.

    Science.gov (United States)

    Ma, Marek

    2013-12-01

    Axonal injury and degeneration, whether primary or secondary, contribute to the morbidity and mortality seen in many acquired and inherited central nervous system (CNS) and peripheral nervous system (PNS) disorders, such as traumatic brain injury, spinal cord injury, cerebral ischemia, neurodegenerative diseases, and peripheral neuropathies. The calpain family of proteases has been mechanistically linked to the dysfunction and degeneration of axons. While the direct mechanisms by which transection, mechanical strain, ischemia, or complement activation trigger intra-axonal calpain activity are likely different, the downstream effects of unregulated calpain activity may be similar in seemingly disparate diseases. In this review, a brief examination of axonal structure is followed by a focused overview of the calpain family. Finally, the mechanisms by which calpains may disrupt the axonal cytoskeleton, transport, and specialized domains (axon initial segment, nodes, and terminals) are discussed.

  9. Angels and Degenerates: Artistic Virtuosity and Degeneration Theory in Fin de Siècle Fiction

    OpenAIRE

    2015-01-01

    The aim in "Angels and Degenerates: Artistic Virtuosity and Degeneration Theory in Fin de Siècle Fiction" is to complicate the popular image of the fin de siècle as uniformly pessimistic by examining the continuities between a range of novelists, as well as other late nineteenth century writers from such disparate fields as psychology and cultural criticism, as they critique degeneration theory. Some of these writers, like Thomas Hardy, H.G. Wells, and Sarah Grand, are typically read as promo...

  10. The gametic central cell of Arabidopsis determines the lifespan of adjacent accessory cells.

    Science.gov (United States)

    Kägi, Christina; Baumann, Nadine; Nielsen, Nicola; Stierhof, York-Dieter; Gross-Hardt, Rita

    2010-12-21

    Plant germ cells develop in specialized haploid structures, termed gametophytes. The female gametophyte patterns of flowering plants are diverse, with often unknown adaptive value. Here we present the Arabidopsis fiona mutant, which forms a female gametophyte that is structurally and functionally reminiscent of a phylogenetic distant female gametophyte. The respective changes include a modified reproductive behavior of one of the female germ cells (central cell) and an extended lifespan of three adjacent accessory cells (antipodals). FIONA encodes the cysteinyl t-RNA synthetase SYCO ARATH (SYCO), which is expressed and required in the central cell but not in the antipodals, suggesting that antipodal lifespan is controlled by the adjacent gamete. SYCO localizes to the mitochondria, and ultrastructural analysis of mutant central cells revealed that the protein is necessary for mitochondrial cristae integrity. Furthermore, a dominant ATP/ADP translocator caused mitochondrial cristae degeneration and extended antipodal lifespan when expressed in the central cell of wild-type plants. Notably, this construct did not affect antipodal lifespan when expressed in antipodals. Our results thus identify an unexpected noncell autonomous role for mitochondria in the regulation of cellular lifespan and provide a basis for the coordinated development of gametic and nongametic cells.

  11. Degenerate target sites mediate rapid primed CRISPR adaptation.

    Science.gov (United States)

    Fineran, Peter C; Gerritzen, Matthias J H; Suárez-Diez, María; Künne, Tim; Boekhorst, Jos; van Hijum, Sacha A F T; Staals, Raymond H J; Brouns, Stan J J

    2014-04-22

    Prokaryotes encode adaptive immune systems, called CRISPR-Cas (clustered regularly interspaced short palindromic repeats-CRISPR associated), to provide resistance against mobile invaders, such as viruses and plasmids. Host immunity is based on incorporation of invader DNA sequences in a memory locus (CRISPR), the formation of guide RNAs from this locus, and the degradation of cognate invader DNA (protospacer). Invaders can escape type I-E CRISPR-Cas immunity in Escherichia coli K12 by making point mutations in the seed region of the protospacer or its adjacent motif (PAM), but hosts quickly restore immunity by integrating new spacers in a positive-feedback process termed "priming." Here, by using a randomized protospacer and PAM library and high-throughput plasmid loss assays, we provide a systematic analysis of the constraints of both direct interference and subsequent priming in E. coli. We have defined a high-resolution genetic map of direct interference by Cascade and Cas3, which includes five positions of the protospacer at 6-nt intervals that readily tolerate mutations. Importantly, we show that priming is an extremely robust process capable of using degenerate target regions, with up to 13 mutations throughout the PAM and protospacer region. Priming is influenced by the number of mismatches, their position, and is nucleotide dependent. Our findings imply that even outdated spacers containing many mismatches can induce a rapid primed CRISPR response against diversified or related invaders, giving microbes an advantage in the coevolutionary arms race with their invaders.

  12. Segmentation of antiperspirants and deodorants

    OpenAIRE

    KRÁL, Tomáš

    2009-01-01

    The goal of Master's Thesis on topic Segmentation of antiperspirants and deodorants is to discover differences in consumer's behaviour, determinate and describe segments of consumers based on these differences and propose marketing strategy for the most attractive segments. Theoretical part describes market segmentation in general, process of segmentation and segmentation criteria. Analytic part characterizes Czech market of antiperspirants and deodorants, analyzes ACNielsen market data and d...

  13. a segmentation approach

    African Journals Online (AJOL)

    kirstam

    a visitor survey was conducted at the Cape Town International Jazz ... 13Key words: dining motives, tipping, black diners, market segmentation, South .... and tipping behaviour as well as the findings from cross-cultural tipping and market.

  14. Segmental tuberculosis verrucosa cutis

    Directory of Open Access Journals (Sweden)

    Hanumanthappa H

    1994-01-01

    Full Text Available A case of segmental Tuberculosis Verrucosa Cutis is reported in 10 year old boy. The condition was resembling the ascending lymphangitic type of sporotrichosis. The lesions cleared on treatment with INH 150 mg daily for 6 months.

  15. Market segmentation: venezuelan adrs

    OpenAIRE

    Urbi Garay; Maximiliano González

    2012-01-01

    The foreign exchange controls imposed by Venezuela in 2003, constitute a natural experiment that allows researchers to observe the effects of exchange controls on stock market segmentation. This paper provides empirical evidence that, although the Venezuelan capital market as a whole was highly segmented before the controls were imposed, shares in the firm CANTV were, through its American Depositary Receipts (ADRs), partially integrated with the global market. Following the imposition of the ...

  16. Segmentation of choroidal neovascularization in fundus fluorescein angiograms.

    Science.gov (United States)

    Abdelmoula, Walid M; Shah, Syed M; Fahmy, Ahmed S

    2013-05-01

    Choroidal neovascularization (CNV) is a common manifestation of age-related macular degeneration (AMD). It is characterized by the growth of abnormal blood vessels in the choroidal layer causing blurring and deterioration of the vision. In late stages, these abnormal vessels can rupture the retinal layers causing complete loss of vision at the affected regions. Determining the CNV size and type in fluorescein angiograms is required for proper treatment and prognosis of the disease. Computer-aided methods for CNV segmentation is needed not only to reduce the burden of manual segmentation but also to reduce inter- and intraobserver variability. In this paper, we present a framework for segmenting CNV lesions based on parametric modeling of the intensity variation in fundus fluorescein angiograms. First, a novel model is proposed to describe the temporal intensity variation at each pixel in image sequences acquired by fluorescein angiography. The set of model parameters at each pixel are used to segment the image into regions of homogeneous parameters. Preliminary results on datasets from 21 patients with Wet-AMD show the potential of the method to segment CNV lesions in close agreement with the manual segmentation.

  17. PIV Measurements and Mechanisms of Adjacent Synthetic Jets Interactions

    Institute of Scientific and Technical Information of China (English)

    LUO Zhen-Bing; XIA Zhi-Xun

    2008-01-01

    Interactions of adjacent synthetic jet actuators with varying relative amplitude and the relative phase of driving voltage are measured using a particle image velocimetry(PIV).Varying relative amplitude or relative phase of driving voltage of the adjacent actuators vectors the direction of the ensuing merged jet of the adjacent synthetic jets.The vectoring mechanism of the adjacent vortex pairs,attract-impact causing deflection(AICD),is provided to explain why the merged jet is generally vectored to the side of the phase-leading synthetic jet or the synthetic jet with higher driving voltage.

  18. MR findings of degenerating parenchymal neurocysticercosis

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Yul; Chung, Eun A; Yang, Ik; Park, Hae Jung; Chung, Soo Young [Hallym Univ. Kangnam Sungshim Hospital, Seoul (Korea, Republic of)

    1996-06-01

    To evaluate MR imaging findings of degenerating parenchymal neurocysticercosis and to determine the characteristics which distinguish it from other brain diseases. MR imagings of 19 patients (56 lesions) of degenerating parenchymal neurocysticercosis were retrospectively evaluated, focusing on the size and location of lesions signal intensity patterns of cyst fluid and wall, the extent of the surrounding edema and features of contrast enhancement. Degenerating parenchymal neurocysticercosis was located in gray or subcortical while matter in 89.3% of 56 lesions (50/56) ; most of these (98.2%) were smaller than 2 cm in diameter. Cyst fluid signal was hyperintense relative to CSF on T1 and proton density weighted images (92.9%). A hypointense signal rim of the cyst wall was noted in the lesions on proton density (92.9%) and T2 weighted (98.2%) images, Surrounding edema was mostly mild. Peripheral rim enhancement was noted in all lesions, and this was frequently irregular and lobulated (67.9%) with a focal defect in the enhancing rim(41.1%). Findings which could be helpful in distinguishing degenerating parencymal neurocysticercosis from other brain diseases are as follows : small, superficial lesions ; hyperintense signal of the cyst fluid on T1 and proton density weighted images ; hypointense signal of the cyst wall on proton density and T2 weighted images ; relatively mild extent of surrounding edema, and peripheral rim enhancement which is frequently irregular and lobulated with a focal defect in the enhancing rim.

  19. Single Degenerate Progenitors of Type Ia Supernovae

    Science.gov (United States)

    Bours, Madelon; Toonen, Silvia; Nelemans, Gijs

    2013-01-01

    There is a general agreement that Type Ia supernovae correspond to the thermonuclear runaway of a white dwarf (WD) in a compact binary. The details of these progenitor systems are still unclear. Using the population synthesis code SeBa and several assumption for the WD retention efficiency, we estimate the delay times and supernova rates for the single degenerate scenario.

  20. Driving and Age-Related Macular Degeneration

    Science.gov (United States)

    Owsley, Cynthia; McGwin, Gerald, Jr.

    2008-01-01

    This article reviews the research literature on driving and age-related macular degeneration, which is motivated by the link between driving and the quality of life of older adults and their increased collision rate. It addresses the risk of crashes, driving performance, driving difficulty, self-regulation, and interventions to enhance, safety,…

  1. The nature of apraxia in corticobasal degeneration.

    Science.gov (United States)

    Leiguarda, R; Lees, A J; Merello, M; Starkstein, S; Marsden, C D

    1994-01-01

    Although apraxia is one of the most frequent signs in corticobasal degeneration, the phenomenology of this disorder has not been formally examined. Hence 10 patients with corticobasal degeneration were studied with a standardised evaluation for different types of apraxia. To minimise the confounding effects of the primary motor disorder, apraxia was assessed in the least affected limb. Whereas none of the patients showed buccofacial apraxia, seven showed deficits on tests of ideomotor apraxia and movement imitation, four on tests of sequential arm movements (all of whom had ideomotor apraxia), and three on tests of ideational apraxia (all of whom had ideomotor apraxia). Ideomotor apraxia significantly correlated with deficit in both the mini mental state examination and in a task sensitive to frontal lobe dysfunction (picture arrangement). Two of the three patients with ideomotor apraxia and ideational apraxia showed severe cognitive impairments. The alien limb behaviour was present only in patients with ideomotor apraxia. In conclusion, ideomotor apraxia is the most frequent type of apraxia in corticobasal degeneration, and may be due to dysfunction of the supplementary motor area. There is a subgroup of patients with corticobasal degeneration who have a severe apraxia (ideomotor and ideational apraxia), which correlates with global cognitive impairment, and may result from additional parietal or diffuse cortical damage. PMID:8163995

  2. Specific heats of degenerate ideal gases

    OpenAIRE

    Caruso, Francisco; Oguri, Vitor; Silveira, Felipe

    2017-01-01

    From arguments based on Heisenberg's uncertainty principle and Pauli's exclusion principle, the molar specific heats of degenerate ideal gases at low temperatures are estimated, giving rise to values consistent with the Nerst-Planck Principle (third law of Thermodynamics). The Bose-Einstein condensation phenomenon based on the behavior of specific heat of massive and non-relativistic boson gases is also presented.

  3. Transversal heteroclinic orbits in general degenerate cases

    Institute of Scientific and Technical Information of China (English)

    朱德明

    1996-01-01

    A geometrical method using the exponential dichotomy and the invariant manifold thoery is given to set up the criteria for the existence of transversal and tangential heterodinic orbits under the most general degenerate cases. Conclusions given here extend and contain the relevant known results.

  4. Depression in Age-Related Macular Degeneration

    Science.gov (United States)

    Casten, Robin; Rovner, Barry

    2008-01-01

    Age-related macular degeneration (AMD) is a major cause of disability in the elderly, substantially degrades the quality of their lives, and is a risk factor for depression. Rates of depression in AMD are substantially greater than those found in the general population of older people, and are on par with those of other chronic and disabling…

  5. DNA sequencing by synthesis with degenerate primers

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The degenerate primer-based sequencing Was developed by a synthesis method(DP-SBS)for high-throughput DNA sequencing,in which a set of degenerate primers are hybridized on the arrayed DNA templates and extended by DNA polymerase on microarrays.In this method,adifferent set of degenerate primers containing a give nnumber(n)of degenerate nucleotides at the 3'-ends were annealed to the sequenced templates that were immobilized on the solid surface.The nucleotides(n+1)on the template sequences were determined by detecting the incorporation of fluorescent labeled nucleotides.The fluorescent labeled nucleotide was incorporated into the primer in a base-specific manner after the enzymatic primer extension reactions and nine-base length were read out accurately.The main advanmge of the DP-SBS is that the method only uses very conventional biochemical reagents and avoids the complicated special chemical reagents for removing the labeled nucleotides and reactivating the primer for further extension.From the present study,it is found that the DP-SBS method is reliable,simple,and cost-effective for laboratory-sequencing a large amount of short DNA fragments.

  6. Nonunital Spectral Triples Associated to Degenerate Metrics

    Science.gov (United States)

    Rennie, A.

    We show that one can define (p,∞)-summable spectral triples using degenerate metrics on smooth manifolds. Furthermore, these triples satisfy Connes-Moscovici's discrete and finite dimension spectrum hypothesis, allowing one to use the Local Index Theorem [1] to compute the pairing with K-theory. We demonstrate this with a concrete example.

  7. Extended polyglutamine tracts cause aggregation and structural perturbation of an adjacent beta barrel protein.

    Science.gov (United States)

    Ignatova, Zoya; Gierasch, Lila M

    2006-05-05

    Formation of fibrillar intranuclear inclusions and related neuropathologies of the CAG-repeat disorders are linked to the expansion of a polyglutamine tract. Despite considerable effort, the etiology of these devastating diseases remains unclear. Although polypeptides with glutamine tracts recapitulate many of the observed characteristics of the gene products with CAG repeats, such as in vitro and in vivo aggregation and toxicity in model organisms, extended polyglutamine segments have also been reported to structurally perturb proteins into which they are inserted. Additionally, the sequence context of a polyglutamine tract has recently been shown to modulate its propensity to aggregate. These findings raise the possibility that indirect influences of the repeat tract on adjacent protein domains are contributory to pathologies. Destabilization of an adjacent domain may lead to loss of function, as well as favoring non-native structures in the neighboring domain causing them to be prone to intermolecular association and consequent aggregation. To explore these phenomena, we have used chimeras of a well studied globular protein and exon 1 of huntingtin. We find that expansion of the polyglutamine segment beyond the pathological threshold (>35 glutamines) results in structural perturbation of the neighboring protein whether the huntingtin exon is N- or C-terminal. Elongation of the polyglutamine region also substantially increases the propensity of the chimera to aggregate, both in vitro and in vivo, and in vitro aggregation kinetics of a chimera with a 53-glutamine repeat follow a nucleation polymerization mechanism with a monomeric nucleus.

  8. Strategic market segmentation

    Directory of Open Access Journals (Sweden)

    Maričić Branko R.

    2015-01-01

    Full Text Available Strategic planning of marketing activities is the basis of business success in modern business environment. Customers are not homogenous in their preferences and expectations. Formulating an adequate marketing strategy, focused on realization of company's strategic objectives, requires segmented approach to the market that appreciates differences in expectations and preferences of customers. One of significant activities in strategic planning of marketing activities is market segmentation. Strategic planning imposes a need to plan marketing activities according to strategically important segments on the long term basis. At the same time, there is a need to revise and adapt marketing activities on the short term basis. There are number of criteria based on which market segmentation is performed. The paper will consider effectiveness and efficiency of different market segmentation criteria based on empirical research of customer expectations and preferences. The analysis will include traditional criteria and criteria based on behavioral model. The research implications will be analyzed from the perspective of selection of the most adequate market segmentation criteria in strategic planning of marketing activities.

  9. Skin Images Segmentation

    Directory of Open Access Journals (Sweden)

    Ali E. Zaart

    2010-01-01

    Full Text Available Problem statement: Image segmentation is a fundamental step in many applications of image processing. Skin cancer has been the most common of all new cancers detected each year. At early stage detection of skin cancer, simple and economic treatment can cure it mostly. An accurate segmentation of skin images can help the diagnosis to define well the region of the cancer. The principal approach of segmentation is based on thresholding (classification that is lied to the problem of the thresholds estimation. Approach: The objective of this study is to develop a method to segment the skin images based on a mixture of Beta distributions. We assume that the data in skin images can be modeled by a mixture of Beta distributions. We used an unsupervised learning technique with Beta distribution to estimate the statistical parameters of the data in skin image and then estimate the thresholds for segmentation. Results: The proposed method of skin images segmentation was implemented and tested on different skin images. We obtained very good results in comparing with the same techniques with Gamma distribution. Conclusion: The experiment showed that the proposed method obtained very good results but it requires more testing on different types of skin images.

  10. Unsupervised Spectral Mesh Segmentation Driven by Heterogeneous Graphs.

    Science.gov (United States)

    Theologou, Panagiotis; Pratikakis, Ioannis; Theoharis, Theoharis

    2017-02-01

    A fully automatic mesh segmentation scheme using heterogeneous graphs is presented. We introduce a spectral framework where local geometry affinities are coupled with surface patch affinities. A heterogeneous graph is constructed combining two distinct graphs: a weighted graph based on adjacency of patches of an initial over-segmentation, and the weighted dual mesh graph. The partitioning relies on processing each eigenvector of the heterogeneous graph Laplacian individually, taking into account the nodal set and nodal domain theory. Experiments on standard datasets show that the proposed unsupervised approach outperforms the state-of-the-art unsupervised methodologies and is comparable to the best supervised approaches.

  11. Degeneration of the cervical disc: histology compared with radiography and magnetic resonance imaging

    Energy Technology Data Exchange (ETDEWEB)

    Christe, A.; Vock, P. [University of Berne, Department of Radiology, Inselspital, Berne (Switzerland); Laeubli, R.; Berlemann, U. [University of Berne, Department of Orthopaedic Surgery, Inselspital, Berne (Switzerland); Guzman, R.; Schroth, G. [University of Berne, Department of Neuroradiology, Inselspital, Berne (Switzerland); Moore, R.J. [Institute of Medical and Veterinary Science, Adelaide (Australia); Loevblad, K.O. [University of Berne, Department of Neuroradiology, Inselspital, Berne (Switzerland); Geneva University Hospital, Neuroradiology SRRI, Geneva 14 (Switzerland)

    2005-10-01

    Decisions about the treatment of neck pain are largely made on the basis of information gained from plain X-rays and magnetic resonance imaging (MRI), which are used routinely as part of preliminary investigation. We performed a descriptive cadaveric study to compare histology with radiography and MRI. We correlated plain radiography, disc height [Farfan index (FI)] and MRI findings with histology to assess the ability of radiology to detect significant pathologic lesions. The study included 52 motion segments from nine subjects over the age of 50, who underwent routine hospital autopsy. Disc degeneration was assessed by histology, radiography, disc height (FI: anterior disc height plus posterior disc height divided by anterioposterior diameter) and MRI using established grading systems. Most of the discs were classified radiologically as grade 1 (19/52), grade 2 (13/52), grade 3 (9/52) or grade 4 (3/52). Eight of the discs were graded as normal. The distribution of MRI grades was grade 0 (9/36), grade 1 (9/36), grade 2 (7/36), grade 3 (8/36) and grade 4 (3/36). Half of the discs (26/52) showed advanced (grade 4) degeneration histologically. FI correlated with histological grade (P=0.013), MRI grade (P=0.02) and radiological grade (P<0.001) of degeneration. Radiological and histological grade of degeneration showed a weak correlation (r=0.3, P=0.033). MRI correlated with overall histological grade (r=0.41, P=0.015, n=34). Histological features (e.g., tears, rim lesions, prolapse of nucleus material) were poorly recognised by MRI, which had a sensitivity for disc material prolapse and annulus tears of less than 40%. Our study showed that discs from patients over 50 years are histologically severely degenerated; however, these changes may not be detected by conventional radiography and MRI. (orig.)

  12. Quasiconformal mappings and degenerate elliptic and parabolic equations

    Directory of Open Access Journals (Sweden)

    Filippo Chiarenza

    1987-11-01

    Full Text Available In this paper two Harnak inequalities are proved concerning a degenerate elliptic and a degenerate parabolic equation. In both cases the weight giving the degeneracy is a power of the jacobian of a quasiconformal mapping.

  13. Degenerate solutions obtained from several variants of factor analysis

    NARCIS (Netherlands)

    Zijlstra, Bonne J.H.; Kiers, Henk A.L.

    2002-01-01

    Considerable research has been performed concerning degenerate solutions from the Parafac model. However, degenerate solutions have also been reported to occur with the shifted multiplicative model and a model for component analysis of multitrait multimethod matrices. Furthermore, we obtained

  14. Axonal degeneration and regeneration in rat uterus during the estrous cycle.

    Science.gov (United States)

    Zoubina, E V; Smith, P G

    2000-11-01

    Uterine innervation of the adult virgin rat changes throughout the estrous cycle. Nerves immunoreactive for the pan-neuronal marker protein gene product 9.5 and the sympathetic marker dopamine beta-hydroxylase are maximal at diestrus and minimal at estrus, whereas presumptive sensory and parasympathetic axons are unchanged. In the present study, we used quantitative electron microscopy to determine if depletion of immunoreactive nerves from the myometrium is due to loss of structurally intact axons, and whether this occurs through degeneration or retraction. Numbers of intact myometrial axons per unit sectional area were greatest at diestrus and least at estrus, while myometrial area was smallest at diestrus and greatest at estrus. However, depletion of intact axons at estrus was evident even after correcting for changes in uterine size. Varicosities adjacent to smooth muscle cells did not vary significantly with respect to their ultrastructural features or distance to the nearest smooth muscle target cell. Because retracting axons show increases in organelle content and distances to target cells, retraction probably does not play a major role in reducing uterine innervation. In contrast, axons with ultrastructural features consistent with degeneration (organelle and axolemmal disintegration, abnormal electron opacity, dense inclusion bodies) were significantly increased at proestrus and estrus. Growth cones were observed only at metestrus and diestrus. We conclude that cyclical degeneration and regeneration of myometrial innervation is a normal feature of the virgin adult rat.

  15. Evaluation of intravertebral changes associated with the disk degeneration based on the MRI findings

    Energy Technology Data Exchange (ETDEWEB)

    Saiki, Natoru [Dokkyo Univ. School of Medicine, Mibu, Tochigi (Japan)

    2000-03-01

    The magnetic resonance images (MRI) of 441 vertebral bodies of the 199 patients with intravertebral abnormality associated with adjacent disk degeneration were evaluated according to the Modic classification and a new geographic classification. They were also evaluated in relation with the various factors including disk space narrowing, vacuum phenomenon, disk herniation, Schmorl's node, ostephyte formation and spondylolisthesis. The new geographic classification is based on the three factors; depth of invasion: stage 1 (thin layer along the end-plate), stage 2 (less than a half of the vertebral height) and stage 3 (more than a half of the vertebral height), shape: end-plate type, Schmorl's node type, triangle type, meniscus type and band type, location: front type, center type, rear type, front and rear type and whole type. Only about a half of the vertebral bodies with intervertebral abnormality showed bilateral invasion adjacent to the degenerative disks on both sides and the superior edges were much more frequently involved than the inferior ones. There was relatively higher incidence (7%) of Modic Type I degeneration defined as high signal intensity (HSI) on T2 weighted spin-echo images (T2WI) and low signal intensity (LSI) on T1 weighted spin-echo images (T1WI) representing vascularized fibrous tissue than those previously reported. On the other hand there was relatively lower incidence (5%) of Modic Type II degeneration defined as high or iso intensity on T1WI and HSI on T2WI. Triangle front type was seen in almost a half of the vertebrae in stage 2 and stage 3, and the rest was divided into meniscus type and band type almost evenly. The end plate front type must be a precursor of the triangle front type. The Schmorl's node type was considered to be a precursor of the meniscus type as well as band type in some but many must stay in its form transformed to Type II degeneration. In general, the intravertebral abnormality may not be necessary to

  16. Cav1.4 L-Type Calcium Channels Contribute to Calpain Activation in Degenerating Photoreceptors of rd1 Mice.

    Directory of Open Access Journals (Sweden)

    Christian Schön

    Full Text Available Retinitis pigmentosa is an inherited blinding disorder characterized by progressive degeneration and loss of photoreceptors. The exact mechanism of degeneration and cell death of photoreceptors is not known, but is thought to involve disturbed Ca2+-signaling. Ca2+ can enter the photoreceptor cell via outer segment cyclic nucleotide-gated (CNG channels or synaptic Cav1.4 L-type voltage-gated calcium channels (VGCC. Previously, we have shown that genetic ablation of the Cngb1 gene encoding the B subunit of the rod CNG channel delays the fast progressing degeneration in the rd1 mutant mouse model of retinitis pigmentosa. In this study, we crossbred rd1 mice with the Cacna1f-deficient mouse lacking the Cav1.4 α1 subunit of the L-type VGCC. Longitudinal in vivo examinations of photoreceptor layer thickness by optical coherence tomography revealed a significant, but not sustained delay of retinal degeneration in Cacna1f x rd1 double mutant mice compared to rd1 mice. This was accompanied by a reduction of TUNEL positive cells in the early phase of rod degeneration. Remarkably, Cacna1f x rd1 double mutant mice displayed a strong decrease in the activation of the Ca2+-dependent protease calpain during photoreceptor loss. Our results show that genetic deletion of the synaptic Cav1.4 L-type VGCCs impairs calpain activation and leads to a short-term preservation of photoreceptors in the rd1 mouse.

  17. Rediscovering market segmentation.

    Science.gov (United States)

    Yankelovich, Daniel; Meer, David

    2006-02-01

    In 1964, Daniel Yankelovich introduced in the pages of HBR the concept of nondemographic segmentation, by which he meant the classification of consumers according to criteria other than age, residence, income, and such. The predictive power of marketing studies based on demographics was no longer strong enough to serve as a basis for marketing strategy, he argued. Buying patterns had become far better guides to consumers' future purchases. In addition, properly constructed nondemographic segmentations could help companies determine which products to develop, which distribution channels to sell them in, how much to charge for them, and how to advertise them. But more than 40 years later, nondemographic segmentation has become just as unenlightening as demographic segmentation had been. Today, the technique is used almost exclusively to fulfill the needs of advertising, which it serves mainly by populating commercials with characters that viewers can identify with. It is true that psychographic types like "High-Tech Harry" and "Joe Six-Pack" may capture some truth about real people's lifestyles, attitudes, self-image, and aspirations. But they are no better than demographics at predicting purchase behavior. Thus they give corporate decision makers very little idea of how to keep customers or capture new ones. Now, Daniel Yankelovich returns to these pages, with consultant David Meer, to argue the case for a broad view of nondemographic segmentation. They describe the elements of a smart segmentation strategy, explaining how segmentations meant to strengthen brand identity differ from those capable of telling a company which markets it should enter and what goods to make. And they introduce their "gravity of decision spectrum", a tool that focuses on the form of consumer behavior that should be of the greatest interest to marketers--the importance that consumers place on a product or product category.

  18. Segmentation of Color Images Based on Different Segmentation Techniques

    Directory of Open Access Journals (Sweden)

    Purnashti Bhosale

    2013-03-01

    Full Text Available In this paper, we propose an Color image segmentation algorithm based on different segmentation techniques. We recognize the background objects such as the sky, ground, and trees etc based on the color and texture information using various methods of segmentation. The study of segmentation techniques by using different threshold methods such as global and local techniques and they are compared with one another so as to choose the best technique for threshold segmentation. Further segmentation is done by using clustering method and Graph cut method to improve the results of segmentation.

  19. Novel active contour model based on multi-variate local Gaussian distribution for local segmentation of MR brain images

    Science.gov (United States)

    Zheng, Qiang; Li, Honglun; Fan, Baode; Wu, Shuanhu; Xu, Jindong

    2017-09-01

    Active contour model (ACM) has been one of the most widely utilized methods in magnetic resonance (MR) brain image segmentation because of its ability of capturing topology changes. However, most of the existing ACMs only consider single-slice information in MR brain image data, i.e., the information used in ACMs based segmentation method is extracted only from one slice of MR brain image, which cannot take full advantage of the adjacent slice images' information, and cannot satisfy the local segmentation of MR brain images. In this paper, a novel ACM is proposed to solve the problem discussed above, which is based on multi-variate local Gaussian distribution and combines the adjacent slice images' information in MR brain image data to satisfy segmentation. The segmentation is finally achieved through maximizing the likelihood estimation. Experiments demonstrate the advantages of the proposed ACM over the single-slice ACM in local segmentation of MR brain image series.

  20. Semantic segmentation of multispectral overhead imagery

    Science.gov (United States)

    Prasad, Lakshman; Pope, Paul A.; Sentz, Kari

    2016-05-01

    Land cover classification uses multispectral pixel information to separate image regions into categories. Image segmentation seeks to separate image regions into objects and features based on spectral and spatial image properties. However, making sense of complex imagery typically requires identifying image regions that are often a heterogeneous mixture of categories and features that constitute functional semantic units such as industrial, residential, or commercial areas. This requires leveraging both spectral classification and spatial feature extraction synergistically to synthesize such complex but meaningful image units. We present an efficient graphical model for extracting such semantically cohesive regions. We employ an initial hierarchical segmentation of images into features represented as nodes of an attributed graph that represents feature properties as well as their adjacency relations with other features. This provides a framework to group spectrally and structurally diverse features, which are nevertheless semantically cohesive, based on user-driven identifications of features and their contextual relationships in the graph. We propose an efficient method to construct, store, and search an augmented graph that captures nonadjacent vicinity relationships of features. This graph can be used to query for semantic notional units consisting of ontologically diverse features by constraining it to specific query node types and their indicated/desired spatial interaction characteristics. User interaction with, and labeling of, initially segmented and categorized image feature graph can then be used to learn feature (node) and regional (subgraph) ontologies as constraints, and to identify other similar semantic units as connected components of the constraint-pruned augmented graph of a query image.

  1. Segmented conjugated polymers

    Indian Academy of Sciences (India)

    G Padmanaban; S Ramakrishnan

    2003-08-01

    Segmented conjugated polymers, wherein the conjugation is randomly truncated by varying lengths of non-conjugated segments, form an interesting class of polymers as they not only represent systems of varying stiffness, but also ones where the backbone can be construed as being made up of chromophores of varying excitation energies. The latter feature, especially when the chromophores are fluorescent, like in MEHPPV, makes these systems particularly interesting from the photophysics point of view. Segmented MEHPPV- samples, where x represents the mole fraction of conjugated segments, were prepared by a novel approach that utilizes a suitable precursor wherein selective elimination of one of the two eliminatable groups is affected; the uneliminated units serve as conjugation truncations. Control of the composition x of the precursor therefore permits one to prepare segmented MEHPPV- samples with varying levels of conjugation (elimination). Using fluorescence spectroscopy, we have seen that even in single isolated polymer chains, energy migration from the shorter (higher energy) chromophores to longer (lower energy) ones occurs – the extent of which depends on the level of conjugation. Further, by varying the solvent composition, it is seen that the extent of energy transfer and the formation of poorly emissive inter-chromophore excitons are greatly enhanced with increasing amounts of non-solvent. A typical S-shaped curve represents the variation of emission yields as a function of composition suggestive of a cooperative collapse of the polymer coil, reminiscent of conformational transitions seen in biological macromolecules.

  2. Scorpion image segmentation system

    Science.gov (United States)

    Joseph, E.; Aibinu, A. M.; Sadiq, B. A.; Bello Salau, H.; Salami, M. J. E.

    2013-12-01

    Death as a result of scorpion sting has been a major public health problem in developing countries. Despite the high rate of death as a result of scorpion sting, little report exists in literature of intelligent device and system for automatic detection of scorpion. This paper proposed a digital image processing approach based on the floresencing characteristics of Scorpion under Ultra-violet (UV) light for automatic detection and identification of scorpion. The acquired UV-based images undergo pre-processing to equalize uneven illumination and colour space channel separation. The extracted channels are then segmented into two non-overlapping classes. It has been observed that simple thresholding of the green channel of the acquired RGB UV-based image is sufficient for segmenting Scorpion from other background components in the acquired image. Two approaches to image segmentation have also been proposed in this work, namely, the simple average segmentation technique and K-means image segmentation. The proposed algorithm has been tested on over 40 UV scorpion images obtained from different part of the world and results obtained show an average accuracy of 97.7% in correctly classifying the pixel into two non-overlapping clusters. The proposed 1system will eliminate the problem associated with some of the existing manual approaches presently in use for scorpion detection.

  3. Study on Optimization of Phase Offset at Adjacent Intersections

    Directory of Open Access Journals (Sweden)

    Yuanli GU

    2010-11-01

    Full Text Available Optimization of the phase offset at adjacent intersections is the key parameter regarding coordinated control of traffic signal for adjacent intersections, which decides the effect of the coordinated control for adjacent intersections. According to characters of saturated traffic flow of Chinese urban road, this thesis establishes a model for optimization of phase offset for adjacent interactions and finds a solution from such model by adopting genetic algorithm. The model is verified by actual traffic flow datum of two adjacent signal intersections on Changan Avenue. Then a comparison is made between the optimization result of such model and that of the existing mathematical method and SYNCHRO model, which indicates that the model established by this thesis can reduce the delay suffered by vehicles at the intersections and increase the traffic efficiency of the intersections.

  4. Segmented heterochromia in scalp hair.

    Science.gov (United States)

    Yoon, Kyeong Han; Kim, Daehwan; Sohn, Seonghyang; Lee, Won Soo

    2003-12-01

    Segmented heterochromia of scalp hair is characterized by the irregularly alternating segmentation of hair into dark and light bands and is known to be associated with iron deficiency anemia. The authors report the case of an 11-year-old boy with segmented heterochromia associated with iron deficiency anemia. After 11 months of iron replacement, the boy's segmented heterochromic hair recovered completely.

  5. The distribution of Schmorl's nodes in patients with low back pain or radiculopathy and their correlation with degeneration of lumbar intervertebral discs%许莫氏结节在腰腿痛患者中的分布特点及与腰椎间盘退变的相关性分析

    Institute of Scientific and Technical Information of China (English)

    陈意磊; 周志杰; 范顺武; 赵凤东; 方向前

    2013-01-01

    Objective To evaluate the distribution of Schmorl's nodes (SN) in patients with low back pain or radiculopathy,and to analyze the correlation between SN and degeneration of lumbar intervertebral discs.Methods In 2012,1024 patients with low back pain or sciatica were examined by magnetic resonance (MR) scan and plain film.There were 448 males and 576 females,with an average age of (54.3 ± 12.7) years (range,22-90).The features distribution of SN in lumbar endplate on age,sex,segment and the type and grade of intervertebral disc degeneration were analyzed retrospectively.Results Among 5120 lumbar intervertebral segments of the 1024 patients,295 (28.8%) cases and 532 (5.2%) endplates were involved with SN,302 located in the cranial and 230 in the caudal endplate.According to percent prevalence per lumbar segment,L1,2 was the most common level (29.1%),followed by L3,4 (23.7%) and L2,3 (21.1%).The incidence of SN was positively correlated with elder age,but not with sex,body weight,height,or body mass index.SN occurred more often in bulging,extrusion,Modic changes,spondylolisthesis and osteophyte comparing with normal disc or protrusion or high intensity zone.The distributions of the grade of intervertebral disc degeneration were significantly different between groups with and without adjacent SN.Intervertebral discs with adjacent SN were more degenerated than those without adjacent SN.The number,size and volume of SN were associated with the degrade of intervertebral discs degeneration.SN was divided into two types,i.e.,"acute edematous" SN and "non-acute"SN,according to the signal type on T1-and T2-weighted MR images,and the degeneration of the corresponding intervertebral discs was more severe in the latter than the former group.Conclusion SN occurred more often in the upper lumbar spine and cranial endplate in patients with low back pain or radiculopathy.SN were correlated with elder age and the degeneration of lumbar intervertebral discs.The number

  6. On the perception of “segmental intonation”: F0 context effects on sibilant identification in German

    DEFF Research Database (Denmark)

    Niebuhr, Oliver

    2017-01-01

    of the fricative in this context will also be high or low. This context-matching effect has been termed “segmental intonation”. While there is accumulating evidence for segmental intonation in speech production, less is known about if and how segmental intonation is actually integrated in the perception....... Furthermore, the results are discussed with respect to reaction-time measurements and an additional effect of the quality of the adjacent vowel phoneme on sibilant identification....

  7. Optimally segmented magnetic structures

    DEFF Research Database (Denmark)

    Insinga, Andrea Roberto; Bahl, Christian; Bjørk, Rasmus;

    ], or are applicable only to analytically solvable geometries[4]. In addition, some questions remained fundamentally unanswered, such as how to segment a given design into N uniformly magnetized pieces.Our method calculates the globally optimal shape and magnetization direction of each segment inside a certain......We present a semi-analytical algorithm for magnet design problems, which calculates the optimal way to subdivide a given design region into uniformly magnetized segments.The availability of powerful rare-earth magnetic materials such as Nd-Fe-B has broadened the range of applications of permanent...... designarea with an optional constraint on the total amount of magnetic material. The method can be applied to any objective functional which is linear respect to the field, and with any combination of linear materials. Being based on an analytical-optimization approach, the algorithm is not computationally...

  8. Segmentation of complex document

    Directory of Open Access Journals (Sweden)

    Souad Oudjemia

    2014-06-01

    Full Text Available In this paper we present a method for segmentation of documents image with complex structure. This technique based on GLCM (Grey Level Co-occurrence Matrix used to segment this type of document in three regions namely, 'graphics', 'background' and 'text'. Very briefly, this method is to divide the document image, in block size chosen after a series of tests and then applying the co-occurrence matrix to each block in order to extract five textural parameters which are energy, entropy, the sum entropy, difference entropy and standard deviation. These parameters are then used to classify the image into three regions using the k-means algorithm; the last step of segmentation is obtained by grouping connected pixels. Two performance measurements are performed for both graphics and text zones; we have obtained a classification rate of 98.3% and a Misclassification rate of 1.79%.

  9. Microscopic Halftone Image Segmentation

    Institute of Scientific and Technical Information of China (English)

    WANG Yong-gang; YANG Jie; DING Yong-sheng

    2004-01-01

    Microscopic halftone image recognition and analysis can provide quantitative evidence for printing quality control and fault diagnosis of printing devices, while halftone image segmentation is one of the significant steps during the procedure. Automatic segmentation on microscopic dots by the aid of the Fuzzy C-Means (FCM) method that takes account of the fuzziness of halftone image and utilizes its color information adequately is realized. Then some examples show the technique effective and simple with better performance of noise immunity than some usual methods. In addition, the segmentation results obtained by the FCM in different color spaces are compared, which indicates that the method using the FCM in the f1f2f3 color space is superior to the rest.

  10. Ultracompact quantum splitter of degenerate photon pairs

    CERN Document Server

    He, Jiakun; Casas-Bedoya, Alvaro; Zhang, Yanbing; Xiong, Chunle; Eggleton, Benjamin J

    2015-01-01

    Integrated sources of indistinguishable photons have attracted a lot of attention because of their applications in quantum communication and optical quantum computing. Here, we demonstrate an ultra-compact quantum splitter for degenerate single photons based on a monolithic chip incorporating Sagnac loop and a micro-ring resonator with a footprint of 0.011 mm2, generating and deterministically splitting indistinguishable photon pairs using time-reversed Hong-Ou-Mandel interference. The ring resonator provides enhanced photon generation rate, and the Sagnac loop ensures the photons travel through equal path lengths and interfere with the correct phase to enable the reversed HOM effect to take place. In the experiment, we observed a HOM dip visibility of 94.5 +- 3.3 %, indicating the photons generated by the degenerate single photon source are in a suitable state for further integration with other components for quantum applications, such as controlled-NOT gates.

  11. Acquired hepatocerebral degeneration: A case report

    Institute of Scientific and Technical Information of China (English)

    Wei-Xing Chen; Ping Wang; Sen-Xiang Yan; You-Ming Li; Chao-Hui Yu; Ling-Ling Jiang

    2005-01-01

    AIM: Acquired hepatocerebral degeneration (AHD) is an exceptional type of hepatic encephalopathies (HE). It is characterized by neuropsychiatric and extrapyramidal symptomathology similar to that seen in hepatolenticular degeneration (Wilson's disease). In this paper, we report a case of AHD with unusual presenting features.METHODS: A 28-year-old man with AHD was described and the literature was reviewed.RESULTS: The man had a history of HBV-related liver cirrhosis. He was admitted to our hospital with apathy,dysarthria, mild consciousness impairment and extrapyramidal symptoms after hematemesis. By review of the literature,cases with AHD often did not present consciousness impairment. So our case was once diagnosed incorrectly as Wilson's disease.CONCLUSION: AHD is a rare syndrome and its variable clinical manifestations make it difficult to be diagnosed.But we believe that extensive examination and thorough understanding of the disease are beneficial to a correct diagnosis. Moreover, biocoene is effective in treating the case.

  12. Small automorphic representations and degenerate Whittaker vectors

    CERN Document Server

    Gustafsson, Henrik P A; Persson, Daniel

    2014-01-01

    We investigate Fourier coefficients of automorphic forms on split simply-laced Lie groups G. We show that for automorphic representations of small Gelfand-Kirillov dimension the Fourier coefficients are completely determined by certain degenerate Whittaker vectors on G. Although we expect our results to hold for arbitrary simply-laced groups, we give complete proofs only for G=SL(3) and G=SL(4). This is based on a method of Ginzburg that associates Fourier coefficients of automorphic forms with nilpotent orbits of G. Our results complement and extend recent results of Miller and Sahi. We also use our formalism to calculate various local (real and p-adic) spherical vectors of minimal representations of the exceptional groups E_6, E_7, E_8 using global (adelic) degenerate Whittaker vectors, correctly reproducing existing results for such spherical vectors obtained by very different methods.

  13. GPS Control Segment Improvements

    Science.gov (United States)

    2015-04-29

    Systems Center GPS Control Segment Improvements Mr. Tim McIntyre GPS Product Support Manager GPS Ops Support and Sustainment Division Peterson...DATE 29 APR 2015 2. REPORT TYPE 3. DATES COVERED 00-00-2015 to 00-00-2015 4. TITLE AND SUBTITLE GPS Control Segment Improvements 5a. CONTRACT...ORGANIZATION NAME(S) AND ADDRESS(ES) Air Force Space Command,Space and Missile Systems Center, GPS Ops Support and Sustainment Division,Peterson AFB,CO,80916 8

  14. Statistical Images Segmentation

    Directory of Open Access Journals (Sweden)

    Corina Curilă

    2008-05-01

    Full Text Available This paper deals with fuzzy statistical imagesegmentation. We introduce a new hierarchicalMarkovian fuzzy hidden field model, which extends to thefuzzy case the classical Pérez and Heitz hard model. Twofuzzy statistical segmentation methods related with themodel proposed are defined in this paper and we show viasimulations that they are competitive with, in some casesthan, the classical Maximum Posterior Mode (MPMbased methods. Furthermore, they are faster, which willshould facilitate extensions to more than two hard classesin future work. In addition, the model proposed isapplicable to the multiscale segmentation andmultiresolution images fusion problems.

  15. Anterograde degeneration along the visual pathway after optic nerve injury.

    Directory of Open Access Journals (Sweden)

    Yuyi You

    Full Text Available PURPOSE: To investigate anterograde degenerative changes along the visual pathway in a rat model of optic nerve axotomy. METHODS: Optic nerve transection was performed in adult Sprague-Dawley rats. Animals were sacrificed at regular time intervals and tissues harvested. Immunoblotting followed by densitometric analysis was used to determine the phosphorylation profile of Akt in the dorsal lateral geniculate nucleus (dLGN and the primary visual cortex (V1. The neuronal cell size and cell density were measured in the dLGN and the V1 using Nissl staining. The prevalence of apoptosis was characterized by terminal deoxynucleotidyl-transferase-mediated biotin-dUTP nick end labelling (TUNEL histochemistry. Caspase-3 antibodies were also used to identify apoptotic cells. Neurons and astrocytes were detected using NeuN and glial fibrillary acidic protein (GFAP, respectively. RESULTS: An early and sustained loss of Akt phosphorylation was observed after optic nerve transection in both dLGN and V1. At week one, a decrease in the neuronal cell size (50.5±4.9 vs 60.3±5.0 µm(2, P = 0.042 and an increase of TUNEL positive cells (7.9±0.6 vs 1.4±0.5 ×10(2 cells/mm(2, P<0.001 were evident in the dLGN but not in V1. A significant decline in neuronal cell number (14.5±0.1 vs 17.4±1.3 ×10(2 cells/mm(2, P = 0.048, cell size (42.5±4.3 vs 62.1±4.7 µm(2, P = 0.001 and an increase in apoptotic cells (5.6±0.5 vs 2.0±0.4 ×10(2 cells/mm(2, P<0.001 appeared in V1 initially at one month post-transection. The changes in the visual pathway continued through two months. Both neuronal cells and GFAP-positive glial cells were affected in this anterograde degeneration along the visual pathway. CONCLUSIONS: Anterograde degeneration along the visual pathway takes place in target relay (LGN and visual cortex following the optic nerve injury. Apoptosis was observed in both neural and adjacent glial cells. Reduction of Akt phosphorylation preceded cellular and apoptotic

  16. Anterograde degeneration along the visual pathway after optic nerve injury.

    Science.gov (United States)

    You, Yuyi; Gupta, Vivek K; Graham, Stuart L; Klistorner, Alexander

    2012-01-01

    To investigate anterograde degenerative changes along the visual pathway in a rat model of optic nerve axotomy. Optic nerve transection was performed in adult Sprague-Dawley rats. Animals were sacrificed at regular time intervals and tissues harvested. Immunoblotting followed by densitometric analysis was used to determine the phosphorylation profile of Akt in the dorsal lateral geniculate nucleus (dLGN) and the primary visual cortex (V1). The neuronal cell size and cell density were measured in the dLGN and the V1 using Nissl staining. The prevalence of apoptosis was characterized by terminal deoxynucleotidyl-transferase-mediated biotin-dUTP nick end labelling (TUNEL) histochemistry. Caspase-3 antibodies were also used to identify apoptotic cells. Neurons and astrocytes were detected using NeuN and glial fibrillary acidic protein (GFAP), respectively. An early and sustained loss of Akt phosphorylation was observed after optic nerve transection in both dLGN and V1. At week one, a decrease in the neuronal cell size (50.5±4.9 vs 60.3±5.0 µm(2), P = 0.042) and an increase of TUNEL positive cells (7.9±0.6 vs 1.4±0.5 ×10(2) cells/mm(2), P<0.001) were evident in the dLGN but not in V1. A significant decline in neuronal cell number (14.5±0.1 vs 17.4±1.3 ×10(2) cells/mm(2), P = 0.048), cell size (42.5±4.3 vs 62.1±4.7 µm(2), P = 0.001) and an increase in apoptotic cells (5.6±0.5 vs 2.0±0.4 ×10(2) cells/mm(2), P<0.001) appeared in V1 initially at one month post-transection. The changes in the visual pathway continued through two months. Both neuronal cells and GFAP-positive glial cells were affected in this anterograde degeneration along the visual pathway. Anterograde degeneration along the visual pathway takes place in target relay (LGN) and visual cortex following the optic nerve injury. Apoptosis was observed in both neural and adjacent glial cells. Reduction of Akt phosphorylation preceded cellular and apoptotic changes.

  17. Dichromatic Langmuir waves in degenerate quantum plasma

    Science.gov (United States)

    Dubinov, A. E.; Kitayev, I. N.

    2015-06-01

    Langmuir waves in fully degenerate quantum plasma are considered. It is shown that, in the linear approximation, Langmuir waves are always dichromatic. The low-frequency component of the waves corresponds to classical Langmuir waves, while the high-frequency component, to free-electron quantum oscillations. The nonlinear problem on the profile of dichromatic Langmuir waves is solved. Solutions in the form of a superposition of waves and in the form of beatings of its components are obtained.

  18. Immunology of age related macular degeneration

    Institute of Scientific and Technical Information of China (English)

    Kijlstra Aize; Yang Peizeng

    2011-01-01

    @@ Age-related macular degeneration(AMD)is the most important cause of blindness in persons over 55 years of age in the Western world.In view of the increasing life expectancy we can assume that the problem will increase dramatically over the coming decades unless preventive or therapeutic measures are developed.Towards this goal many groups all over the world have performed epidemiological studies to identify potential risk factors for AMD.

  19. Degenerate spacetimes in first order gravity

    CERN Document Server

    Kaul, Romesh K

    2016-01-01

    We present a systematic framework to obtain the most general solutions of the equations of motion in first order gravity theory with degenerate tetrads. There are many possible solutions. Generically, these exhibit non-vanishing torsion even in the absence of any matter coupling. These solutions are shown to contain a special set of eight configurations which are associated with the homogeneous model three-geometries of Thurston.

  20. Degenerate RFID Channel Modeling for Positioning Applications

    Directory of Open Access Journals (Sweden)

    A. Povalac

    2012-12-01

    Full Text Available This paper introduces the theory of channel modeling for positioning applications in UHF RFID. It explains basic parameters for channel characterization from both the narrowband and wideband point of view. More details are given about ranging and direction finding. Finally, several positioning scenarios are analyzed with developed channel models. All the described models use a degenerate channel, i.e. combined signal propagation from the transmitter to the tag and from the tag to the receiver.

  1. Depression in Age-Related Macular Degeneration

    OpenAIRE

    Casten,Robin; Rovner,Barry

    2008-01-01

    Age-related macular degeneration (AMD) is a major cause of disability in the elderly, substantially degrades the quality of their lives, and is a risk factor for depression. Rates of depression in AMD are substantially greater than those found in the general population of older people, and are on par with those of other chronic and disabling diseases. This article discusses the effect of depression on vision-related disability in patients with AMD, suggests methods for screening for depressio...

  2. Stem cell horizons in intervertebral disc degeneration

    Directory of Open Access Journals (Sweden)

    Joseph Ciacci

    2009-01-01

    Full Text Available Joseph Ciacci1, Allen Ho1,2, Christopher P Ames3, Rahul Jandial41Division of Neurosurgery, University of California, San Diego, La Jolla, California, USA; 2Del E Webb Neurosciences, Aging and Stem Cell Research Center, The Burnham Institute for Medical Research, La Jolla, California, USA; 3Department of Neurological Surgery, University of California, San Francisco, San Francisco, CA, USA; 4Division of Neurosurgery, Department of Surgery, City of Hope Cancer Center, Duarte, CA, USAAbstract: Intervertebral disc degeneration remains a pervasive and intractable disease arising from a combination of aging and stress on the back and spine. The growing field of regenerative medicine brings the promise of stem cells in the treatment of disc disease. Scientists and physicians hope to employ stem cells not only to stop, but also reverse degeneration. However, there are many important outstanding issues, including the hostile avascular, apoptotic physiological environment of the intervertebral disc, and the difficulty of obtaining mesenchymal stem cells, and directing them towards chondrocytic differentiation and integration within the nucleus pulposus of the disc. Given the recent advances in minimally invasive spine surgery, and developing body of work on stem cell manipulation and transplantation, stem cells are uniquely poised to bring about large-scale improvements in treatment and outcomes for degenerative disc disease. In this review we will first discuss the cellular and molecular factors influencing degeneration, and then examine the efficacy and difficulties of stem cell transplantation.Keywords: intervertebral disc degeneration, stem cells, disc disease, mesenchymal stem cells, stem cell transplantation

  3. Rehabilitation Approaches in Macular Degeneration Patients

    OpenAIRE

    Maniglia, Marcello; Benoit R Cottereau; Soler, Vincent; Trotter, Yves

    2016-01-01

    Age related macular degeneration (AMD) is a visual disease that affects elderly population. It entails a progressive loss of central vision whose consequences are dramatic for the patient’s quality of life. Current rehabilitation programs are restricted to technical aids based on visual devices. They only temporarily improve specific visual functions such as reading skills. Considering the rapid increase of the aging population worldwide, it is crucial to intensify clinical research on AMD in...

  4. Controllability of nonlinear degenerate parabolic cascade systems

    Directory of Open Access Journals (Sweden)

    Mamadou Birba

    2016-08-01

    Full Text Available This article studies of null controllability property of nonlinear coupled one dimensional degenerate parabolic equations. These equations form a cascade system, that is, the solution of the first equation acts as a control in the second equation and the control function acts only directly on the first equation. We prove positive null controllability results when the control and a coupling set have nonempty intersection.

  5. Animal models of age related macular degeneration

    OpenAIRE

    Pennesi, Mark E.; Neuringer, Martha; Courtney, Robert J.

    2012-01-01

    Age related macular degeneration (AMD) is the leading cause of vision loss of those over the age of 65 in the industrialized world. The prevalence and need to develop effective treatments for AMD has lead to the development of multiple animal models. AMD is a complex and heterogeneous disease that involves the interaction of both genetic and environmental factors with the unique anatomy of the human macula. Models in mice, rats, rabbits, pigs and non-human primates have recreated many of the ...

  6. Pathology and possible mechanisms of nervous system response to disc degeneration.

    Science.gov (United States)

    Brisby, Helena

    2006-04-01

    Degeneration of the intervertebral disc is clinically considered to be an important source of pain in patients with low-back pain. Disc deterioration and/or degeneration may influence the nervous system by stimulation of nociceptors in the anulus fibrosus, causing nociceptive pain that is often referred to as discogenic pain. The stimulation of the nociceptors may be of mechanical or inflammatory origin. Deterioration of a disc with loss of normal structure and weight-bearing properties may lead to abnormal motions that cause mechanical stimulation. This theory is supported by the fact that patients commonly experience an increase in pain with weight-bearing and certain movements. In addition, an ingrowth of vessels and nerve fibers into deeper layers of the anulus fibrosus has been observed in degenerated discs. A large number of inflammatory and signaling substances, such as tumor necrosis factor and interleukins (interleukin-1beta, interleukin-6, and interleukin-8), may also play a role in the development of back pain. Independent of stimulus of the nociceptors, the pain impulses are conducted through myelinated A delta fibers and unmyelinated C fibers to the dorsal root ganglion and continue by way of the spinothalamic tract to the thalamus and the somatosensory cortex. In response to stimulation of the nociceptors in the disc, the somatosensory system may increase its sensitivity, resulting in a nonfunctional response; that is, normally innocuous stimuli may generate an amplified response (peripheral sensitization). When disc degeneration leads to a disc herniation, the adjacent nervous system structures, such as the nerve roots or the dorsal root ganglion, can be affected, causing neuropathic pain of mechanical or biochemical origin. Disc deterioration also influences other spinal structures, such as facet joints, ligaments, and muscles, which can also become pain generators. Thus, disc degeneration may be responsible for the development of chronic low

  7. Conceptual foundations of schizophrenia: I. Degeneration.

    Science.gov (United States)

    Barrett, R J

    1998-10-01

    This is the first of two papers that aim to identify some of the institutional processes of 19th century European psychiatry, and some prevailing cultural themes of that era that played a role in shaping the development of schizophrenia as a disease concept. Three areas of psychiatric history are examined: the first is concerned with the key figures who coined the concept of dementia praecox; the second with the rise of the asylum; and the third is to do with the ideology of 19th century psychiatric science and its relationship to a broader intellectual milieu. These three literatures are examined for common themes. The theme of degeneration is evident in all three literatures, and denotes both a biological process (neuro-degeneration) and a moral state (degeneracy). The idea of degeneration, a pervasive cultural theme of the 19th century, dominated psychiatric thinking long before schizophrenia was developed as a diagnostic category. It contributed to the ideational form-work that gave foundation, structure and shape to the concept of schizophrenia.

  8. Propagation of Disturbances in Degenerate Quantum Systems

    CERN Document Server

    Chancellor, Nicholas

    2011-01-01

    Disturbances in gapless quantum many-body models are known to travel an unlimited distance throughout the system. Here, we explore this phenomenon in finite clusters with degenerate ground states. The specific model studied here is the one-dimensional J1-J2 Heisenberg Hamiltonian at and close to the Majumdar-Ghosh point. Both open and periodic boundary conditions are considered. Quenches are performed using a local magnetic field. The degenerate Majumdar-Ghosh ground state allows disturbances which carry quantum entanglement to propagate throughout the system, and thus dephase the entire system within the degenerate subspace. These disturbances can also carry polarization, but not energy, as all energy is stored locally. The local evolution of the part of the system where energy is stored drives the rest of the system through long-range entanglement. We also examine approximations for the ground state of this Hamiltonian in the strong field limit, and study how couplings away from the Majumdar-Ghosh point aff...

  9. Visual hallucinations in patients with macular degeneration.

    Science.gov (United States)

    Holroyd, S; Rabins, P V; Finkelstein, D; Nicholson, M C; Chase, G A; Wisniewski, S C

    1992-12-01

    This study was undertaken to determine the prevalence of visual hallucinations in patients with macular degeneration, describe such hallucinations phenomenologically, and possibly determine factors predisposing to their development. Using a case-control design, the authors screened 100 consecutive patients with age-related macular degeneration for visual hallucinations. Each patient with visual hallucinations was matched to the next three patients without hallucinations. The patients and comparison subjects were compared in terms of scores on the Beck Depression Inventory, Eysenck Personality Questionnaire, Telephone Interview for Cognitive Status, and a structured questionnaire including demographic characteristics, family history, and medical and psychiatric history. Ophthalmologic data were obtained by chart review. Of the 100 patients, 13 experienced visual hallucinations. Four variables were significantly associated with having hallucinations: living alone, lower cognition score, history of stroke, and bilaterally worse visual acuity. Hallucinations were not associated with family or personal history of psychiatric disorder or with personality traits. In 11 (84.6%) of the 13 patients, the hallucinations had begun in association with an acute change in vision. These results indicate that visual hallucinations are prevalent among patients with macular degeneration. They appear unrelated to primary psychiatric disorder. The predisposing factors of bilaterally worse vision and living alone support an association with sensory deprivation, while history of stroke and worse cognition support a decreased cortical inhibition theory.

  10. Segmented strings coupled to a B-field

    CERN Document Server

    Vegh, David

    2016-01-01

    In this paper we study segmented strings in AdS$_3$ coupled to a background two-form whose field strength is proportional to the volume form. By changing the coupling, the theory interpolates between the Nambu-Goto string and the $SL(2)$ Wess-Zumino-Witten model. In terms of the kink momentum vectors, the action is independent of the coupling and the classical theory reduces to a single discrete-time Toda-type theory. The WZW model is a singular point in coupling space where the map into Toda variables degenerates.

  11. Sipunculans and segmentation

    DEFF Research Database (Denmark)

    Wanninger, Andreas; Kristof, Alen; Brinkmann, Nora

    2009-01-01

    Comparative molecular, developmental and morphogenetic analyses show that the three major segmented animal groups- Lophotrochozoa, Ecdysozoa and Vertebrata-use a wide range of ontogenetic pathways to establish metameric body organization. Even in the life history of a single specimen, different m...

  12. [Segmental testicular infarction].

    Science.gov (United States)

    Ripa Saldías, L; Guarch Troyas, R; Hualde Alfaro, A; de Pablo Cárdenas, A; Ruiz Ramo, M; Pinós Paul, M

    2006-02-01

    We report the case of a 47 years old man previously diagnosed of left hidrocele. After having a recent mild left testicular pain, an ultrasonografic study revealed a solid hipoecoic testicular lesion rounded by a big hidrocele, suggesting a testicular neoplasm. Radical inguinal orchiectomy was made and pathologic study showed segmental testicular infarction. No malignancy was found. We review the literature of the topic.

  13. Dictionary Based Image Segmentation

    DEFF Research Database (Denmark)

    Dahl, Anders Bjorholm; Dahl, Vedrana Andersen

    2015-01-01

    We propose a method for weakly supervised segmentation of natural images, which may contain both textured or non-textured regions. Our texture representation is based on a dictionary of image patches. To divide an image into separated regions with similar texture we use an implicit level sets...

  14. [New drug therapy for retinal degeneration].

    Science.gov (United States)

    Ohguro, Hiroshi

    2008-01-01

    Retinitis pigmentosa (RP) is an inherited retinal degeneration characterized by nyctalopia, ring scotoma, and bone-spicule pigmentation of the retina. So far, no effective therapy has been found for RP. As a possible molecular etiology of RP, retina-specific gene deficits are most likely involved, but little has been identified in terms of intracellular mechanisms leading to retinal photoreceptor cell death at post-translational levels. In order to find an effective therapy for RP, we must look for underlying common mechanisms that are responsible for the development of RP, instead of designing a specific therapy for each of the RP types with different causes. Therefore, in the present study, several animal models with different causes of RP were studied, including (1)Royal College of Surgeons (RCS) rats with a deficit of retinal pigment epithelium (RPE) function caused by rhodopsin mutation; (2) P23H rats, (3) S334ter rats, (4) photo stress rats, (5) retinal degeneration (rd) mice with a deficit of phosphodiesterase(PDE) function; and (6) cancer-associated retinopathy (CAR) model rats with a deficit of recoverin-dependent photoreceptor adaptation function. In each of these models, the following assessments were made in order to elucidate common pathological mechanisms among the models: (1) retinal function assessed by electroretinogram (ERG), (2) retinal morphology, (3) retinoid analysis, (4) rhodopsin regeneration, (5) rhodopsin phosphorylation and dephosphorylation, and (6) cytosolic cGMP levels. We found that unregulated photoreceptor adaptation processes caused by an imbalance of rhodopsin phosphorylation and dephosphorylation caused retinal dysfunction leading to photoreceptor cell death. As possible candidate drugs for normalizing these retinal dysfunctions and stopping further retinal degeneration, nilvadipine, a Ca channel blocker, retinoid derivatives, and anthocyanine were chosen and tested to determine their effect on the above animal models with

  15. Q344ter mutation causes mislocalization of rhodopsin molecules that are catalytically active: a mouse model of Q344ter-induced retinal degeneration.

    Directory of Open Access Journals (Sweden)

    Francis Concepcion

    Full Text Available Q344ter is a naturally occurring rhodopsin mutation in humans that causes autosomal dominant retinal degeneration through mechanisms that are not fully understood, but are thought to involve an early termination that removed the trafficking signal, QVAPA, leading to its mislocalization in the rod photoreceptor cell. To better understand the disease mechanism(s, transgenic mice that express Q344ter were generated and crossed with rhodopsin knockout mice. Dark-reared Q344ter(rho+/- mice exhibited retinal degeneration, demonstrating that rhodopsin mislocalization caused photoreceptor cell death. This degeneration is exacerbated by light-exposure and is correlated with the activation of transducin as well as other G-protein signaling pathways. We observed numerous sub-micrometer sized vesicles in the inter-photoreceptor space of Q344ter(rho+/- and Q344ter(rho-/- retinas, similar to that seen in another rhodopsin mutant, P347S. Whereas light microscopy failed to reveal outer segment structures in Q344ter(rho-/- rods, shortened and disorganized rod outer segment structures were visible using electron microscopy. Thus, some Q344ter molecules trafficked to the outer segment and formed disc structures, albeit inefficiently, in the absence of full length wildtype rhodopsin. These findings helped to establish the in vivo role of the QVAPA domain as well as the pathways leading to Q344ter-induced retinal degeneration.

  16. Automatic segmentation of leg bones by using active contours.

    Science.gov (United States)

    Kim, Sunhee; Kim, Youngjun; Park, Sehyung; Lee, Deukhee

    2014-01-01

    In this paper, we present a new active contours model to segment human leg bones in computed tomography images that is based on a variable-weighted combination of local and global intensity. This model can split an object surrounded by both weak and strong boundaries, and also distinguish very adjacent objects with those boundaries. The ability of this model is required for segmentation in medical images, e.g., human leg bones, which are usually composed of highly inhomogeneous objects and where the distances among organs are very close. We developed an evolution equation of a level set function whose zero level set represents a contour. An initial contour is automatically obtained by applying a histogram based multiphase segmentation method. We experimented with computed tomography images from three patients, and demonstrate the efficiency of the proposed method in experimental results.

  17. Lung tumor segmentation in PET images using graph cuts.

    Science.gov (United States)

    Ballangan, Cherry; Wang, Xiuying; Fulham, Michael; Eberl, Stefan; Feng, David Dagan

    2013-03-01

    The aim of segmentation of tumor regions in positron emission tomography (PET) is to provide more accurate measurements of tumor size and extension into adjacent structures, than is possible with visual assessment alone and hence improve patient management decisions. We propose a segmentation energy function for the graph cuts technique to improve lung tumor segmentation with PET. Our segmentation energy is based on an analysis of the tumor voxels in PET images combined with a standardized uptake value (SUV) cost function and a monotonic downhill SUV feature. The monotonic downhill feature avoids segmentation leakage into surrounding tissues with similar or higher PET tracer uptake than the tumor and the SUV cost function improves the boundary definition and also addresses situations where the lung tumor is heterogeneous. We evaluated the method in 42 clinical PET volumes from patients with non-small cell lung cancer (NSCLC). Our method improves segmentation and performs better than region growing approaches, the watershed technique, fuzzy-c-means, region-based active contour and tumor customized downhill.

  18. An automated method for accurate vessel segmentation

    Science.gov (United States)

    Yang, Xin; Liu, Chaoyue; Le Minh, Hung; Wang, Zhiwei; Chien, Aichi; (Tim Cheng, Kwang-Ting

    2017-05-01

    Vessel segmentation is a critical task for various medical applications, such as diagnosis assistance of diabetic retinopathy, quantification of cerebral aneurysm’s growth, and guiding surgery in neurosurgical procedures. Despite technology advances in image segmentation, existing methods still suffer from low accuracy for vessel segmentation in the two challenging while common scenarios in clinical usage: (1) regions with a low signal-to-noise-ratio (SNR), and (2) at vessel boundaries disturbed by adjacent non-vessel pixels. In this paper, we present an automated system which can achieve highly accurate vessel segmentation for both 2D and 3D images even under these challenging scenarios. Three key contributions achieved by our system are: (1) a progressive contrast enhancement method to adaptively enhance contrast of challenging pixels that were otherwise indistinguishable, (2) a boundary refinement method to effectively improve segmentation accuracy at vessel borders based on Canny edge detection, and (3) a content-aware region-of-interests (ROI) adjustment method to automatically determine the locations and sizes of ROIs which contain ambiguous pixels and demand further verification. Extensive evaluation of our method is conducted on both 2D and 3D datasets. On a public 2D retinal dataset (named DRIVE (Staal 2004 IEEE Trans. Med. Imaging 23 501-9)) and our 2D clinical cerebral dataset, our approach achieves superior performance to the state-of-the-art methods including a vesselness based method (Frangi 1998 Int. Conf. on Medical Image Computing and Computer-Assisted Intervention) and an optimally oriented flux (OOF) based method (Law and Chung 2008 European Conf. on Computer Vision). An evaluation on 11 clinical 3D CTA cerebral datasets shows that our method can achieve 94% average accuracy with respect to the manual segmentation reference, which is 23% to 33% better than the five baseline methods (Yushkevich 2006 Neuroimage 31 1116-28; Law and Chung 2008

  19. Segmentation in Tardigrada and diversification of segmental patterns in Panarthropoda.

    Science.gov (United States)

    Smith, Frank W; Goldstein, Bob

    2016-10-31

    The origin and diversification of segmented metazoan body plans has fascinated biologists for over a century. The superphylum Panarthropoda includes three phyla of segmented animals-Euarthropoda, Onychophora, and Tardigrada. This superphylum includes representatives with relatively simple and representatives with relatively complex segmented body plans. At one extreme of this continuum, euarthropods exhibit an incredible diversity of serially homologous segments. Furthermore, distinct tagmosis patterns are exhibited by different classes of euarthropods. At the other extreme, all tardigrades share a simple segmented body plan that consists of a head and four leg-bearing segments. The modular body plans of panarthropods make them a tractable model for understanding diversification of animal body plans more generally. Here we review results of recent morphological and developmental studies of tardigrade segmentation. These results complement investigations of segmentation processes in other panarthropods and paleontological studies to illuminate the earliest steps in the evolution of panarthropod body plans.

  20. Gas samples of Afghanistan and adjacent areas (gasafg.shp)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This shapefile contains points that describe the location of gas samples collected in Afghanistan and adjacent areas and the results of organic geochemical analysis.

  1. Ollier's disease in association with adjacent fibromatosis

    Energy Technology Data Exchange (ETDEWEB)

    Al-Ismail, Khalid; Torreggiani, William C.; Munk, Peter L. [Department of Radiology, Vancouver General Hospital, University of British Columbia, 899 West l2th Avenue, Vancouver, BC (Canada); O' Connell, John X.; Nicolaou, Savvakis [Department of Pathology, Vancouver General Hospital, University of British Columbia, 899 West l2th Avenue, Vancouver, BC (Canada); Masri, Bassam A. [Department of Orthopaedics, Vancouver General Hospital, University of British Columbia, 899 West l2th Avenue, Vancouver, BC (Canada)

    2002-08-01

    Ollier's disease (enchondromatosis) is a nonhereditary disorder of mesodermal dysplasia. It is characterized by the presence of multiple enchondromas that typically affect the metaphyseal ends of bones. The association of Ollier's disease with adjacent fibromatosis has, to our knowledge, not been previously described. We report a case of Ollier's disease in association with soft tissue fibromatosis adjacent to the involved upper arm. (orig.)

  2. Statistical Characterization and Segmentation of Drusen in Fundus Images

    Energy Technology Data Exchange (ETDEWEB)

    Santos-Villalobos, Hector J [ORNL; Karnowski, Thomas Paul [ORNL; Aykac, Deniz [ORNL; Giancardo, Luca [ORNL; Li, Yaquin [University of Tennessee, Knoxville (UTK); Nichols, Trent L [ORNL; Tobin Jr, Kenneth William [ORNL; Chaum, Edward [University of Tennessee, Knoxville (UTK)

    2011-01-01

    Age related Macular Degeneration (AMD) is a disease of the retina associated with aging. AMD progression in patients is characterized by drusen, pigmentation changes, and geographic atrophy, which can be seen using fundus imagery. The level of AMD is characterized by standard scaling methods, which can be somewhat subjective in practice. In this work we propose a statistical image processing approach to segment drusen with the ultimate goal of characterizing the AMD progression in a data set of longitudinal images. The method characterizes retinal structures with a statistical model of the colors in the retina image. When comparing the segmentation results of the method between longitudinal images with known AMD progression and those without, the method detects progression in our longitudinal data set with an area under the receiver operating characteristics curve of 0.99.

  3. Statistical characterization and segmentation of drusen in fundus images.

    Science.gov (United States)

    Santos-Villalobos, H; Karnowski, T P; Aykac, D; Giancardo, L; Li, Y; Nichols, T; Tobin, K W; Chaum, E

    2011-01-01

    Age related Macular Degeneration (AMD) is a disease of the retina associated with aging. AMD progression in patients is characterized by drusen, pigmentation changes, and geographic atrophy, which can be seen using fundus imagery. The level of AMD is characterized by standard scaling methods, which can be somewhat subjective in practice. In this work we propose a statistical image processing approach to segment drusen with the ultimate goal of characterizing the AMD progression in a data set of longitudinal images. The method characterizes retinal structures with a statistical model of the colors in the retina image. When comparing the segmentation results of the method between longitudinal images with known AMD progression and those without, the method detects progression in our longitudinal data set with an area under the receiver operating characteristics curve of 0.99.

  4. Learning at a distance II. Statistical learning of non-adjacent dependencies in a non-human primate.

    Science.gov (United States)

    Newport, Elissa L; Hauser, Marc D; Spaepen, Geertrui; Aslin, Richard N

    2004-09-01

    In earlier work we have shown that adults, infants, and cotton-top tamarin monkeys are capable of computing the probability with which syllables occur in particular orders in rapidly presented streams of human speech, and of using these probabilities to group adjacent syllables into word-like units. We have also investigated adults' learning of regularities among elements that are not adjacent, and have found strong selectivities in their ability to learn various kinds of non-adjacent regularities. In the present paper we investigate the learning of these same non-adjacent regularities in tamarin monkeys, using the same materials and familiarization methods. Three types of languages were constructed. In one, words were formed by statistical regularities between non-adjacent syllables. Words contained predictable relations between syllables 1 and 3; syllable 2 varied. In a second type of language, words were formed by statistical regularities between non-adjacent segments. Words contained predictable relations between consonants; the vowels varied. In a third type of language, also formed by regularities between non-adjacent segments, words contained predictable relations between vowels; the consonants varied. Tamarin monkeys were exposed to these languages in the same fashion as adults (21 min of exposure to a continuous speech stream) and were then tested in a playback paradigm measuring spontaneous looking (no reinforcement). Adult subjects learned the second and third types of language easily, but failed to learn the first. However, tamarin monkeys showed a different pattern, learning the first and third type of languages but not the second. These differences held up over multiple replications, using different sounds instantiating each of the patterns. These results suggest differences among learners in the elementary units perceived in speech (syllables, consonants, and vowels) and/or the distance over which such units can be related, and therefore differences

  5. Market segmentation: Venezuelan ADRs

    Directory of Open Access Journals (Sweden)

    Urbi Garay

    2012-12-01

    Full Text Available The control on foreign exchange imposed by Venezuela in 2003 constitute a natural experiment that allows researchers to observe the effects of exchange controls on stock market segmentation. This paper provides empirical evidence that although the Venezuelan capital market as a whole was highly segmented before the controls were imposed, the shares in the firm CANTV were, through their American Depositary Receipts (ADRs, partially integrated with the global market. Following the imposition of the exchange controls this integration was lost. Research also documents the spectacular and apparently contradictory rise experienced by the Caracas Stock Exchange during the serious economic crisis of 2003. It is argued that, as it happened in Argentina in 2002, the rise in share prices occurred because the depreciation of the Bolívar in the parallel currency market increased the local price of the stocks that had associated ADRs, which were negotiated in dollars.

  6. Segmentation Using Symmetry Deviation

    DEFF Research Database (Denmark)

    Hollensen, Christian; Højgaard, L.; Specht, L.;

    2011-01-01

    segmentations on manual contours was evaluated using concordance index and sensitivity for the hypopharyngeal patients. The resulting concordance index and sensitivity was compared with the result of using a threshold of 3 SUV using a paired t-test. Results: The anatomical and symmetrical atlas was constructed...... and sensitivity of respectively 0.43±0.15 and 0.56±0.18 was acquired. It was compared to the concordance index of segmentation using absolute threshold of 3 SUV giving respectively 0.41±0.16 and 0.51±0.19 for concordance index and sensitivity yielding p-values of 0.33 and 0.01 for a paired t-test respectively....

  7. Connecting textual segments

    DEFF Research Database (Denmark)

    Brügger, Niels

    2017-01-01

    In “Connecting textual segments: A brief history of the web hyperlink” Niels Brügger investigates the history of one of the most fundamental features of the web: the hyperlink. Based on the argument that the web hyperlink is best understood if it is seen as another step in a much longer and broader......-alone computers and in local and global digital networks....

  8. Degenerate Neutrinos in Left Right Symmetric Theory

    OpenAIRE

    Joshipura, Anjan S.

    1994-01-01

    Various hints on the neutrino masses namely, ({\\em i}) the solar neutrino deficit ({\\em ii}) the atmospheric neutrino deficit ({\\em iii}) the need for the dark matter and/or ({\\em iv}) the non-zero neutrinoless double beta decay collectively imply that all the three neutrinos must be nearlty degenerate. This feature can be understood in the left right symmetric theory. We present a model based on the group $SU(2)_{L}\\times SU(2)_R\\times U(1)_{B-L}\\times SU(2)_H$ which can explain the required...

  9. REITERATED HOMOGENIZATION OF DEGENERATE NONLINEAR ELLIPTIC EQUATIONS

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The authors study homogenization of some nonlinear partial differential equations of the form -div (a (hx,h2x,Duh)) = f,where a is periodic in the first two arguments and monotone in the third.In particular the case where a satisfies degenerated structure conditions is studied.It is proved that uh converges weakly in Wo1.1 (Ω) to the unique solution of a limit problem as h →∞.Moreover,explicit expressions for the limit problem are obtained.

  10. Length spectra and degeneration of flat metrics

    CERN Document Server

    Duchin, Moon; Rafi, Kasra

    2009-01-01

    In this paper we consider flat metrics (semi-translation structures) on surfaces of finite type. There are two main results. The first is a complete description of when a set of simple closed curves is spectrally rigid, that is, when the length vector determines a metric among the class of flat metrics. Secondly, we give an embedding into the space of geodesic currents and use this to get a boundary for the space of flat metrics. The geometric interpretation is that flat metrics degenerate to "mixed structures" on the surface: part flat metric and part measured foliation.

  11. Aneutronic Fusion in a Degenerate Plasma

    Energy Technology Data Exchange (ETDEWEB)

    S. Son; N.J. Fisch

    2004-09-03

    In a Fermi-degenerate plasma, the electronic stopping of a slow ion is smaller than that given by the classical formula, because some transitions between the electron states are forbidden. The bremsstrahlung losses are then smaller, so that the nuclear burning of an aneutronic fuel is more efficient. Consequently, there occurs a parameter regime in which self-burning is possible. Practical obstacles in this regime that must be overcome before net energy can be realized include the compression of the fuel to an ultra dense state and the creation of a hot spot.

  12. [Age-related macular degeneration (AMD)].

    Science.gov (United States)

    Michels, Stephan; Kurz-Levin, Malaika

    2009-03-01

    Today age-related macular degeneration (AMD) is the most frequent cause for legal blindness in western industrialized countries. The prevalence of this disease rises with increasing age. A multifactorial pathogenesis of AMD is postulated including genetic predisposition and environmental risk factors. The most relevant modifiable risk factor is smoking. Up to today there is no cure of this chronic disease. Prophylaxis, including a healthy diet and antioxidants as nutrional supplements for selected patients, aims to slow down the disease progression. Significant progress has been made in the treatment of the neovascular form of the disease using inhibitors of the vascular endothelial growth factor (VEGF).

  13. Was Maurice Ravel's illness a corticobasal degeneration?

    Science.gov (United States)

    Baeck, E

    1996-02-01

    The French composer Maurice Ravel (1875-1937) was struck down at the peak of his career by an aphasia and apraxia that destroyed his artistic realization but preserved his musical sensibility and judgment. He died after craniotomy. Multiple hypotheses have been formulated to explain the exact nature of his illness, probably corticobasal degeneration. However, in the absence of a post-mortem examination, the diagnosis must remain speculative despite the accurate descriptions of the symptoms in numerous biographies, the neuro-psychological notes of Théophile Alajouanine and the operative findings of Clovis Vincent.

  14. Precursors of age-related macular degeneration

    DEFF Research Database (Denmark)

    Munch, Inger Christine; Toft, Ulla; Linneberg, Allan;

    2016-01-01

    PURPOSE: To investigate associations of very early age-related macular degeneration (AMD) with daily intake of vitamin A, beta-carotene, vitamin E, vitamin C, zinc and copper and interactions with AMD-associated polymorphisms in complement factor H (CFHY402H) and ARMS2/LOC387715. METHODS: Cross......: In this cross-sectional study, a higher intake of vitamin A increased the risk of macular drusen >63 μm in subjects with CFHY402H. The study supports that vitamin A may be a risk factor for early AMD....

  15. Market segmentation in behavioral perspective.

    OpenAIRE

    Wells, V.K.; Chang, S. W.; Oliveira-Castro, J.M.; Pallister, J.

    2010-01-01

    A segmentation approach is presented using both traditional demographic segmentation bases (age, social class/occupation, and working status) and a segmentation by benefits sought. The benefits sought in this case are utilitarian and informational reinforcement, variables developed from the Behavioral Perspective Model (BPM). Using data from 1,847 consumers and from a total of 76,682 individual purchases, brand choice and price and reinforcement responsiveness were assessed for each segment a...

  16. Affine and degenerate affine BMW algebras: The center

    CERN Document Server

    Daugherty, Zajj; Virk, Rahbar

    2011-01-01

    The degenerate affine and affine BMW algebras arise naturally in the context of Schur-Weyl duality for orthogonal and symplectic Lie algebras and quantum groups, respectively. Cyclotomic BMW algebras, affine Hecke algebras, cyclotomic Hecke algebras, and their degenerate versions are quotients. In this paper the theory is unified by treating the orthogonal and symplectic cases simultaneously; we make an exact parallel between the degenerate affine and affine cases via a new algebra which takes the role of the affine braid group for the degenerate setting. A main result of this paper is an identification of the centers of the affine and degenerate affine BMW algebras in terms of rings of symmetric functions which satisfy a "cancellation property" or "wheel condition" (in the degenerate case, a reformulation of a result of Nazarov). Miraculously, these same rings also arise in Schubert calculus, as the cohomology and K-theory of isotropic Grassmanians and symplectic loop Grassmanians. We also establish new inte...

  17. Affine and degenerate affine BMW algebras: Actions on tensor space

    CERN Document Server

    Daugherty, Zajj; Virk, Rahbar

    2012-01-01

    The affine and degenerate affine Birman-Murakami-Wenzl (BMW) algebras arise naturally in the context of Schur-Weyl duality for orthogonal and symplectic quantum groups and Lie algebras, respectively. Cyclotomic BMW algebras, affine and cyclotomic Hecke algebras, and their degenerate versions are quotients. In this paper we explain how the affine and degenerate affine BMW algebras are tantalizers (tensor power centralizer algebras) by defining actions of the affine braid group and the degenerate affine braid algebra on tensor space and showing that, in important cases, these actions induce actions of the affine and degenerate affine BMW algebras. We then exploit the connection to quantum groups and Lie algebras to determine universal parameters for the affine and degenerate affine BMW algebras. Finally, we show that the universal parameters are central elements--the higher Casimir elements for orthogonal and symplectic enveloping algebras and quantum groups.

  18. Oculomotor paralysis: 3D-CISS MR imaging with MPR in the evaluation of neuralgic manifestation and the adjacent structures

    Energy Technology Data Exchange (ETDEWEB)

    Sun Xiaoli; Liang Changhu [Shandong Medical Imaging Research Institute, Shandong University, Jing-wu Road No. 324, Jinan 250021 (China); Liu Cheng [Shandong Medical Imaging Research Institute, Shandong University, Jing-wu Road No. 324, Jinan 250021 (China)], E-mail: sdsxl2005@126.com; Liu Shuwei; Deng Kai; He Jingzhen [Shandong Medical Imaging Research Institute, Shandong University, Jing-wu Road No. 324, Jinan 250021 (China)

    2010-02-15

    Purpose: To evaluate the value of three-dimensional (3D) constructive interference in steady-state (CISS) magnetic resonance (MR) imaging with multi-planar reconstruction (MPR) in displaying the relationship between the oculomotor nerve and its adjacent structures for patients with oculomotor paralysis. Materials and methods: 17 consecutive patients with oculomotor paralysis were examined with 3D-CISS and conventional spin-echo (SE) sequences on a 1.5-Tesla MR system. Original transverse and MPR images were used for image interpretation. The features of the oculomotor nerve and its adjacent structures were identified. The diagnosis was surgically confirmed in all patients. Results: Through 3D-CISS with MPR images, obvious relationship of the oculomotor nerve and its adjacent structures was demonstrated on 17 patients. Of those oculomotor nerves, 15 were compressed by the arteries (n = 15), one by the craniopharyngioma (n = 1), and another one by the neurofibroma (n = 1). Conclusion: 3D-CISS MR imaging with MPR provides an excellent way to characterize the relationship between the nerve and its adjacent structures in the cisternal segment of the oculomotor nerve in the patients with oculomotor paralysis. Moreover, this method shows anatomical details for imaging diagnosis and surgical procedure.

  19. Market Segmentation for Information Services.

    Science.gov (United States)

    Halperin, Michael

    1981-01-01

    Discusses the advantages and limitations of market segmentation as strategy for the marketing of information services made available by nonprofit organizations, particularly libraries. Market segmentation is defined, a market grid for libraries is described, and the segmentation of information services is outlined. A 16-item reference list is…

  20. Segmenting the Adult Education Market.

    Science.gov (United States)

    Aurand, Tim

    1994-01-01

    Describes market segmentation and how the principles of segmentation can be applied to the adult education market. Indicates that applying segmentation techniques to adult education programs results in programs that are educationally and financially satisfying and serve an appropriate population. (JOW)

  1. Market Segmentation for Information Services.

    Science.gov (United States)

    Halperin, Michael

    1981-01-01

    Discusses the advantages and limitations of market segmentation as strategy for the marketing of information services made available by nonprofit organizations, particularly libraries. Market segmentation is defined, a market grid for libraries is described, and the segmentation of information services is outlined. A 16-item reference list is…

  2. Segmenting the Adult Education Market.

    Science.gov (United States)

    Aurand, Tim

    1994-01-01

    Describes market segmentation and how the principles of segmentation can be applied to the adult education market. Indicates that applying segmentation techniques to adult education programs results in programs that are educationally and financially satisfying and serve an appropriate population. (JOW)

  3. Degenerations and limit Frobenius structures in rigid cohomology

    OpenAIRE

    Lauder, Alan G. B.

    2011-01-01

    We introduce a "limiting Frobenius structure" attached to any degeneration of projective varieties over a finite field of characteristic p which satisfies a p-adic lifting assumption. Our limiting Frobenius structure is shown to be effectively computable in an appropriate sense for a degeneration of projective hypersurfaces. We conjecture that the limiting Frobenius structure relates to the rigid cohomology of a semistable limit of the degeneration through an analogue of the Clemens-Schmidt e...

  4. SARM1 activation triggers axon degeneration locally via NAD+ destruction

    OpenAIRE

    Gerdts, Josiah; Brace, E. J.; Sasaki, Yo; DiAntonio, Aaron; Milbrandt, Jeffrey

    2015-01-01

    Axon degeneration is an intrinsic self-destruction program that underlies axon loss during injury and disease. Sterile alpha and TIR motif containing 1 (SARM1) protein is an essential mediator of axon degeneration. We report that SARM1 initiates a local destruction program involving rapid breakdown of NAD+ after injury. We used an engineered protease-sensitized SARM1 to demonstrate that SARM1 activity is required after axon injury to induce axon degeneration. Dimerization of the Toll-Interleu...

  5. Circummandibular Wires for Treatment of Dentoalveolar Fractures Adjacent to Edentulous Areas: A Report of Two Cases.

    Science.gov (United States)

    Maloney, Karl

    2015-09-01

    In general, dentoalveolar fractures are a common injury seen in emergency departments, dental offices, and oral and maxillofacial surgery practices. These injuries can be the result of direct trauma or indirect trauma. Direct trauma more often causes trauma to the maxillary dentition due to the exposure of the maxillary anterior teeth. Indirect trauma is usually the result of forced occlusion secondary to a blow to the chin or from a whiplash injury. Falls are the most common mechanism of injury seen in the pediatric group. In adolescents, many of these fractures are sustained during sporting activities. However, the use of mouth guards and other protective equipment has decreased this number. Most adult injuries are caused by motor vehicle accidents, contact sports, falls, bicycles, interpersonal violence, medical/dental mishaps, and industrial accidents. Early intervention to reduce and stabilize the fracture is required to establish a bony union and ensure correct function. Most dentoalveolar fractures have bilateral stable adjacent dentition and are treated with a closed technique utilizing an acid-etch/resin splint followed by splint removal at 4 weeks. Other inferior stabilization treatments used are arch bars and other wiring techniques. It is widely accepted that semirigid stabilization techniques, such as an acid-etch/resin splint or wiring procedures, are adequate to treat dentoalveolar fractures. This is in contrast to the treatment of mandible fractures where AO principles of rigid fixation are often followed. Fractures that are unable to be reduced sometimes necessitate an open reduction followed by internal fixation, sometimes using a secondary splint for mobile teeth. In those rare cases when there are not stable adjacent teeth bilaterally other modalities must be considered. In the present report, two cases are presented where circummandibular wires were used to treat fractured mandibular dentoalveolar segments adjacent to edentulous areas.

  6. Integrable systems, toric degenerations and Okounkov bodies

    CERN Document Server

    Harada, Megumi

    2012-01-01

    Let X be a smooth projective variety of dimension n over C equipped with a very ample line bundle L. Using the theory of Okounkov bodies and an associated toric degeneration, we construct -- under a mild technical hypothesis on X -- an integrable system on X in the sense of symplectic geometry. More precisely, we construct a collection of real-valued functions {H_1, ..., H_n} on X which are continuous on all of X, smooth on an open dense subset U of X, and pairwise Poisson-commute on U. Here the symplectic structure on X is the pullback of the Fubini-Study form on P(H^0(X, L)^*) via the Kodaira embedding. The image of the `moment map' (H_1, ..., H_n): X to R^n is precisely the Okounkov body \\Delta = \\Delta(R, v) associated to the homogeneous coordinate ring R of X, and an appropriate choice of valuation v on R. Our main technical tools come from algebraic geometry, differential (Kaehler) geometry, and analysis. Specifically, we use: a toric degeneration of X to a (not necessarily normal) toric variety X_0, th...

  7. MR imaging findings of hypertrophic olivary degeneration

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Do Joong; Jeon, Pyung; Kim, Dong Ik [Yonsei Univ. College of Medicine, Seoul (Korea, Republic of)

    1997-06-01

    To describe the magnetic resonance (MR) imaging findings of hypertrophic olivary degeneration (HOD) MR images of seven patients with HOD were retrospectively reviewed. Two were women and five were men, and they were aged between 48 and 65 (mean 58) years. Imaging examinations were performed with a 1.5-T unit, and the findings were used to evaluate the size and signal intensity of olivary lesions. The time interval from hemorrhagic ictus to MR imaging was between two and 30 months. Follow-up examinations were performed in two patients. All four patients with hemorrhages involving the central tegmental tract in the pons or midbrain showed ipsilateral HOD. Among these four, bilateral HOD was seen in one patient with hemorrhage involving the bilateral central tegmental tract, and in another with tegmental hemorrhage extending to the ipsilateral superior cerebellar peduncle. One patient with cerebellar hemorrhage involving the dentate nucleus had contralateral HOD. Two patients with multiple hemorrhages involving both the pons and cerebellum showed bilateral HOD. Axial MR images showed mild enlargement of the involved olivary mucleus, with high signal intensity on both proton density and T2 weighted images. There was no apparent enhancement on postcontrast T1-weighted images. MR imaging can clearly distinguish secondary olivary degeneration from underlying pathology involving the central tegmental tract in the pons or midbrain and cerebellum. These olivary abnormalities should not, however, be mistaken for primary medullary lesions.

  8. On the degenerated Arnold-Givental conjecture

    CERN Document Server

    Lu, Guangcun

    2008-01-01

    Let $(M, \\omega, \\tau)$ be a real symplectic manifold with nonempty and compact real part $L={\\rm Fix}(\\tau)$. We study the following degenerated version of the Arnold-Givental conjecture: $\\sharp(L\\cap\\phi(L))\\ge{\\rm Cuplength}_{\\F}(L)$ for any Hamiltonian diffeomorphism $\\phi:M\\to M$ and $\\F=\\Z, \\Z_2$. Suppose that $(M, \\omega)$ is geometrical bounded for some $J\\in{\\cal J}(M, \\omega)$ with $\\tau^\\ast J=-J$. We prove $\\sharp(L\\cap\\phi(L))\\ge {\\rm Cuplength}_{\\F}(L)$ for $\\F=\\Z_2$, and $\\F=\\Z_2, \\Z$ if $L$ is orientable, and for every Hamiltonian diffeomorphism $\\phi$ generated by a compactly supported Hamiltonian function whose Hofer norm is less than the minimal area of all nonconstant $J$-holomorphic spheres in $M$. In particular, this implies that the above degenerated Arnold-Givental conjecture holds on the K3-surfaces and closed negative monotone real symplectic manifolds of dimension $2n$ with either $n\\le 3$ or minimal Chern number $N\\ge n-2$. As consequences we get that every Hamiltonian diffeomorph...

  9. Progranulin in frontotemporal lobar degeneration and neuroinflammation

    Directory of Open Access Journals (Sweden)

    Hutton Michael L

    2007-02-01

    Full Text Available Abstract Progranulin (PGRN is a pleiotropic protein that has gained the attention of the neuroscience community with recent discoveries of mutations in the gene for PGRN that cause frontotemporal lobar degeneration (FTLD. Pathogenic mutations in PGRN result in null alleles, and the disease is likely the result of haploinsufficiency. Little is known about the normal function of PGRN in the central nervous system apart from a role in brain development. It is expressed by microglia and neurons. In the periphery, PGRN is involved in wound repair and inflammation. High PGRN expression has been associated with more aggressive growth of various tumors. The properties of full length PGRN are distinct from those of proteolytically derived peptides, referred to as granulins (GRNs. While PGRN has trophic properties, GRNs are more akin to inflammatory mediators such as cytokines. Loss of the neurotrophic properties of PGRN may play a role in selective neuronal degeneration in FTLD, but neuroinflammation may also be important. Gene expression studies suggest that PGRN is up-regulated in a variety of neuroinflammatory conditions, and increased PGRN expression by microglia may play a pivotal role in the response to brain injury, neuroinflammation and neurodegeneration.

  10. SIRT3 Reverses Aging-Associated Degeneration

    Directory of Open Access Journals (Sweden)

    Katharine Brown

    2013-02-01

    Full Text Available Despite recent controversy about their function in some organisms, sirtuins are thought to play evolutionarily conserved roles in lifespan extension. Whether sirtuins can reverse aging-associated degeneration is unknown. Tissue-specific stem cells persist throughout the entire lifespan to repair and maintain tissues, but their self-renewal and differentiation potential become dysregulated with aging. We show that SIRT3, a mammalian sirtuin that regulates the global acetylation landscape of mitochondrial proteins and reduces oxidative stress, is highly enriched in hematopoietic stem cells (HSCs where it regulates a stress response. SIRT3 is dispensable for HSC maintenance and tissue homeostasis at a young age under homeostatic conditions but is essential under stress or at an old age. Importantly, SIRT3 is suppressed with aging, and SIRT3 upregulation in aged HSCs improves their regenerative capacity. Our study illuminates the plasticity of mitochondrial homeostasis controlling stem cell and tissue maintenance during the aging process and shows that aging-associated degeneration can be reversed by a sirtuin.

  11. Disc degeneration-related clinical phenotypes.

    Science.gov (United States)

    Battié, Michele C; Lazáry, Aron; Fairbank, Jeremy; Eisenstein, Stephen; Heywood, Chris; Brayda-Bruno, Marco; Varga, Péter Pál; McCall, Iain

    2014-06-01

    The phenotype, or observable trait of interest, is at the core of studies identifying associated genetic variants and their functional pathways, as well as diagnostics. Yet, despite remarkable technological developments in genotyping and progress in genetic research, relatively little attention has been paid to the equally important issue of phenotype. This is especially true for disc degeneration-related disorders, and the concept of degenerative disc disease, in particular, where there is little consensus or uniformity of definition. Greater attention and rigour are clearly needed in the development of disc degeneration-related clinical phenotypes if we are to see more rapid advancements in knowledge of this area. When selecting phenotypes, a basic decision is whether to focus directly on the complex clinical phenotype (e.g. the clinical syndrome of spinal stenosis), which is ultimately of interest, or an intermediate phenotype (e.g. dural sac cross-sectional area). While both have advantages, it cannot be assumed that associated gene variants will be similarly relevant to both. Among other considerations are factors influencing phenotype identification, comorbidities that are often present, and measurement issues. Genodisc, the European research consortium project on disc-related clinical pathologies has adopted a strategy that will allow for the careful characterisation and examination of both the complex clinical phenotypes of interest and their components.

  12. Metabolic anatomy of paraneoplastic cerebellar degeneration

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, N.E.; Posner, J.B.; Sidtis, J.J.; Moeller, J.R.; Strother, S.C.; Dhawan, V.; Rottenberg, D.A.

    1988-06-01

    Eleven patients with acquired cerebellar degeneration (10 of whom had paraneoplastic cerebellar degeneration (PCD)) were evaluated using neuropsychological tests and /sup 18/F-fluorodeoxyglucose/positron emission tomography to (1) quantify motor, cognitive, and metabolic abnormalities; (2) determine if characteristic alterations in the regional cerebral metabolic rate for glucose (rCMRGlc) are associated with PCD; and (3) correlate behavioral and metabolic measures of disease severity. Eighteen volunteer subjects served as normal controls. Although some PCD neuropsychological test scores were abnormal, these results could not, in general, be dissociated from the effects of dysarthria and ataxia. rCMRGlc was reduced in patients with PCD (versus normal control subjects) in all regions except the brainstem. Analysis of patient and control rCMRGlc data using a mathematical model of regional metabolic interactions revealed two metabolic pattern descriptors, SSF1 and SSF2, which distinguished patients with PCD from normal control subjects; SSF2, which described a metabolic coupling between cerebellum, cuneus, and posterior temporal, lateral frontal, and paracentral cortex, correlated with quantitative indices of cerebellar dysfunction. Our inability to document substantial intellectual impairment in 7 of 10 patients with PCD contrasts with the 50% incidence of dementia in PCD reported by previous investigators. Widespread reductions in PCD rCMRGlc may result from the loss of cerebellar efferents to thalamus and forebrain structures, a reverse cerebellar diaschisis.

  13. Degenerate parametric oscillation in quantum membrane optomechanics

    Science.gov (United States)

    Benito, Mónica; Sánchez Muñoz, Carlos; Navarrete-Benlloch, Carlos

    2016-02-01

    The promise of innovative applications has triggered the development of many modern technologies capable of exploiting quantum effects. But in addition to future applications, such quantum technologies have already provided us with the possibility of accessing quantum-mechanical scenarios that seemed unreachable just a few decades ago. With this spirit, in this work we show that modern optomechanical setups are mature enough to implement one of the most elusive models in the field of open system dynamics: degenerate parametric oscillation. Introduced in the eighties and motivated by its alleged implementability in nonlinear optical resonators, it rapidly became a paradigm for the study of dissipative phase transitions whose corresponding spontaneously broken symmetry is discrete. However, it was found that the intrinsic multimode nature of optical cavities makes it impossible to experimentally study the model all the way through its phase transition. In contrast, here we show that this long-awaited model can be implemented in the motion of a mechanical object dispersively coupled to the light contained in a cavity, when the latter is properly driven with multichromatic laser light. We focus on membranes as the mechanical element, showing that the main signatures of the degenerate parametric oscillation model can be studied in state-of-the-art setups, thus opening the possibility of analyzing spontaneous symmetry breaking and enhanced metrology in one of the cleanest dissipative phase transitions. In addition, the ideas put forward in this work would allow for the dissipative preparation of squeezed mechanical states.

  14. Quasi-degenerate neutrinos in SO(10)

    CERN Document Server

    Joshipura, Anjan S

    2010-01-01

    Quark lepton universality inherent in grand unified theories based on $SO(10)$ gauge group generically leads to hierarchical neutrino masses. We propose a specific ansatz for the structure of Yukawa matrices in $SO(10)$ models which differ from this generic expectations and lead to quasi degenerate neutrinos through the type-I seesaw mechanism. Consistency of this ansatz is demonstrated through a detailed fits to fermion masses and mixing angles all of which can be explained with reasonable accuracy in a model which uses the Higgs fields transforming as $10,120$ and $\\overline{126}$ representations of $SO(10)$. The proposed ansatz is shown to follow from an extended model based on the three generations of the vector like fermions and an $O(3)$ flavour symmetry. Successful numerical fits are also discussed in earlier proposed models which used combination of the type-I and type-II seesaw mechanisms for obtaining quasi degenerate neutrinos. Large neutrino mixing angles emerge as a consequence of neutrino mass d...

  15. Split-remerge method for eliminating processing window artifacts in recursive hierarchical segmentation

    Science.gov (United States)

    Tilton, James C. (Inventor)

    2010-01-01

    A method, computer readable storage, and apparatus for implementing recursive segmentation of data with spatial characteristics into regions including splitting-remerging of pixels with contagious region designations and a user controlled parameter for providing a preference for merging adjacent regions to eliminate window artifacts.

  16. Three-dimensional intravascular ultrasound assessment of noninjured edges of beta-irradiated coronary segments

    NARCIS (Netherlands)

    K. Kozuma (Ken); M.A. Costa (Marco); M. Sabaté (Manel); I.P. Kay (Ian Patrick); J.P. Marijnissen (Johannes); V.L.M.A. Coen (Veronique); P. Serrano (Pedro); J.M.R. Ligthart (Jürgen); P.W.J.C. Serruys (Patrick); P.C. Levendag (Peter)

    2000-01-01

    textabstractBACKGROUND: The "edge effect," late lumen loss at the margins of the treated segment, has become an important issue in the field of coronary brachytherapy. The aim of the present study was to assess the edge effect in noninjured margins adjacent to the irradiated segmen

  17. A cross-language comparison of the use of stress in word segmentation

    NARCIS (Netherlands)

    Tyler, M.D.; Perruchet, P.; Cutler, A.

    2006-01-01

    In spite of our illusions to the contrary, there are few acoustic cues to word boundaries in spoken language. While statistical probabilities between adjacent speech units provide language-general information for speech segmentation, this study shows that language-specific information may also play

  18. 颈椎前路减压人工颈椎间盘置换术与融合术治疗单节段颈椎间盘突出症的短期疗效比较%Clinical outcome of Discover artificial cervical disc replacement versus anterior cervical decompression and fusion for single segment cervical disc herniation

    Institute of Scientific and Technical Information of China (English)

    卡哈尔·艾肯木; 楚戈; 王振斌; 陈继征; 顾文飞; 胡雅斌; 涂来勇; 赵疆; 项泽文

    2014-01-01

    Background: The curative effect of anterior cervical discectomy and fusion (ACDF) is satisfactory for the patients with symptomatic cervical disc herniation. However, it can result in stress increase in adjacent segments and speed up the degen-eration of adjacent segments. Artificial cervical disc replacement (ACDR), a typical non-fusion surgical treatment, may be an alternative to ACDF for cervical disc herniation. Objective:To compare the clinical outcomes between ACDR and ACDF for single segmental cervical disc herniation. Methods:From January 2009 to February 2012, 61 patients with single segmental cervical disc herniation were treated in our hospital. Of them, 26 received Discover ACDF (arthroplasty group) and 35 underwent single-level ACDF (fusion group). Visual analogue scale (VAS) neck/arm pain score, Japanese Orthopedics Association (JOA) score and flexion-exten-sion range of motion of operative and adjacent segments were evaluated preoperatively and 1 week and 3, 6, 12, and 24 months postoperatively. Complications and secondary treatment were recorded. Results:A total of 52 patients (29 in arthroplasty group and 23 in fusion group) were followed up. The average follow-up pe-riod was 15.3 months (range, 12-24 months). The VAS scores of neck pain and upper limb pain and JOA score were signifi-cantly improved during follow up as compared with preoperative ones in all patients (P0.05). In arthroplasty group, there was no significant difference in range of motion of opera-tive and adjacent segments before and after treatment (P>0.05). The rate of fusion achievement was 90.5%. In arthroplasy group, prosthesis antedisplacement (<3 mm) in 2 patients at 6 months after surgery, and cerebrospinal fluid leakage oc-curred 1 patient. In fusion group, adjacent segment disease occurred in one patient who underwent secondary operation. Conclusions:Discover cervical disc replacement is a feasible alternative to ACDF for patients with persistent symptomatic cervical disc

  19. Interactive segmentation for geographic atrophy in retinal fundus images.

    Science.gov (United States)

    Lee, Noah; Smith, R Theodore; Laine, Andrew F

    2008-10-01

    Fundus auto-fluorescence (FAF) imaging is a non-invasive technique for in vivo ophthalmoscopic inspection of age-related macular degeneration (AMD), the most common cause of blindness in developed countries. Geographic atrophy (GA) is an advanced form of AMD and accounts for 12-21% of severe visual loss in this disorder [3]. Automatic quantification of GA is important for determining disease progression and facilitating clinical diagnosis of AMD. The problem of automatic segmentation of pathological images still remains an unsolved problem. In this paper we leverage the watershed transform and generalized non-linear gradient operators for interactive segmentation and present an intuitive and simple approach for geographic atrophy segmentation. We compare our approach with the state of the art random walker [5] algorithm for interactive segmentation using ROC statistics. Quantitative evaluation experiments on 100 FAF images show a mean sensitivity/specificity of 98.3/97.7% for our approach and a mean sensitivity/specificity of 88.2/96.6% for the random walker algorithm.

  20. Genetic and functional dissection of HTRA1 and LOC387715 in age-related macular degeneration.

    Directory of Open Access Journals (Sweden)

    Zhenglin Yang

    2010-02-01

    Full Text Available A common haplotype on 10q26 influences the risk of age-related macular degeneration (AMD and encompasses two genes, LOC387715 and HTRA1. Recent data have suggested that loss of LOC387715, mediated by an insertion/deletion (in/del that destabilizes its message, is causally related with the disorder. Here we show that loss of LOC387715 is insufficient to explain AMD susceptibility, since a nonsense mutation (R38X in this gene that leads to loss of its message resides in a protective haplotype. At the same time, the common disease haplotype tagged by the in/del and rs11200638 has an effect on the transcriptional upregulation of the adjacent gene, HTRA1. These data implicate increased HTRA1 expression in the pathogenesis of AMD and highlight the importance of exploring multiple functional consequences of alleles in haplotypes that confer susceptibility to complex traits.

  1. Patch graft for corneal perforation following trivial trauma in bilateral terrien′s marginal degeneration

    Directory of Open Access Journals (Sweden)

    Merle Fernandes

    2015-01-01

    Full Text Available A young female presented with blurred vision in the left eye after she rubbed her eye. On examination of both eyes, she had 360° thinning adjacent to the limbus, lipid deposition and superficial vascularization with a perforation in the left eye. The patient was diagnosed with bilateral Terrien′s marginal degeneration (TMD with perforation. Corneal topography of the right eye revealed high oblique astigmatism confirming the diagnosis. A peripheral patch graft was performed for the left eye. At 18 months postoperatively, the best-corrected visual acuity was 20/20 in both eyes. The graft was clear. Topography of right eye was stable, and the left eye had oblique astigmatism. Bilateral advanced TMD in a young patient presenting with corneal perforation following trivial trauma is extremely uncommon. Patch graft may be an option for restoring the globe integrity in such cases. Regular follow-up is necessary as the condition progresses slowly.

  2. Iris segmentation using variational level set method

    Science.gov (United States)

    Roy, Kaushik; Bhattacharya, Prabir; Suen, Ching Y.

    2011-04-01

    Continuous efforts have been made to process degraded iris images for enhancement of the iris recognition performance in unconstrained situations. Recently, many researchers have focused on developing the iris segmentation techniques, which can deal with iris images in a non-cooperative environment where the probability of acquiring unideal iris images is very high due to gaze deviation, noise, blurring, and occlusion by eyelashes, eyelids, glasses, and hair. Although there have been many iris segmentation methods, most focus primarily on the accurate detection of iris images captured in a closely controlled environment. The novelty of this research effort is that we propose to apply a variational level set-based curve evolution scheme that uses a significantly larger time step to numerically solve the evolution partial differential equation (PDE) for segmentation of an unideal iris image accurately, and thereby, speeding up the curve evolution process drastically. The iris boundary represented by the variational level set may break and merge naturally during evolution, and thus, the topological changes are handled automatically. The proposed variational model is also robust against poor localization and weak iris/sclera boundaries. In order to solve the size irregularities occurring due to arbitrary shapes of the extracted iris/pupil regions, a simple method is applied based on connection of adjacent contour points. Furthermore, to reduce the noise effect, we apply a pixel-wise adaptive 2D Wiener filter. The verification and identification performance of the proposed scheme is validated on three challenging iris image datasets, namely, the ICE 2005, the WVU Unideal, and the UBIRIS Version 1.

  3. Signs of segmentation?

    DEFF Research Database (Denmark)

    Ilsøe, Anna

    2012-01-01

    This article addresses the contribution of decentralized collective bargaining to the development of different forms of flexicurity for different groups of employees on the Danish labour market. Based on five case studies of company-level bargaining on flexible working hours in Danish industry...... the text of the agreements. On the other hand, less flexible employees often face difficulties in meeting the demands of the agreements and may ultimately be forced to leave the company and rely on unemployment benefits and active labour market policies. In a flexicurity perspective, this development seems...... to imply a segmentation of the Danish workforce regarding hard and soft versions of flexicurity....

  4. Noncooperative Iris Segmentation

    Directory of Open Access Journals (Sweden)

    Elsayed Mostafa

    2012-01-01

    Full Text Available In noncooperative iris recognition one should deal with uncontrolled behavior of the subject as well as uncontrolled lighting conditions. That means eyelids and eyelashes occlusion, non uniform intensities, reflections, imperfect focus, and orientation among the others are to be considered. To cope with this situation a noncooperative iris segmentation algorithm based on numerically stable direct least squares fitting of ellipses model and modified Chan-Vese model (local binary fitting energy with variational level set formulation is to be proposed. The proposed algorithm is tested using CASIA-IrisV3.

  5. The LOFT Ground Segment

    DEFF Research Database (Denmark)

    Bozzo, E.; Antonelli, A.; Argan, A.;

    2014-01-01

    targets per orbit (~90 minutes), providing roughly ~80 GB of proprietary data per day (the proprietary period will be 12 months). The WFM continuously monitors about 1/3 of the sky at a time and provides data for about ~100 sources a day, resulting in a total of ~20 GB of additional telemetry. The LOFT...... we summarize the planned organization of the LOFT ground segment (GS), as established in the mission Yellow Book 1 . We describe the expected GS contributions from ESA and the LOFT consortium. A review is provided of the planned LOFT data products and the details of the data flow, archiving...

  6. Contextual information-aided kidney segmentation in CT sequences

    Science.gov (United States)

    Zhao, Enwei; Liang, Yanmei; Fan, Hailun

    2013-03-01

    Based on the continuity of adjacent slices in a medical image sequence, a slice-based 3-D segmentation framework is constructed to extract the intact kidney by processing all slices automatically in the whole sequence. The framework includes four sections: initial segmentation, selection of the most reliable initial segmentation, location and modification of leakage. The crucial section of the proposed framework is selecting the most reliable initial segmentation image, which will be regarded as the reference image to evaluate the continuity of the following slice. Leakage location is carried out based on the contextual features, and the local iterative thresholding (LIT) is used to modify the leakage. As test examples of the framework, abdominal computed tomography (CT) images in enhanced phases are processed to segment kidney automatically. The total of 392 CT images in 7 sequences from 3 patients are selected as training images to determine the parameters in the database, and other 898 CT images in 21 sequences from 7 patients are used as test images to evaluate the effectiveness of the method. An average of three dimensional Dice similarity coefficient (3-D DSC) of 94.7% and average symmetric surface distance (ASSD) of 0.91 mm are obtained, which indicate that the intact kidney can be perfectly extracted with hardly any leakage automatically.

  7. Image segmentation by hierarchial agglomeration of polygons using ecological statistics

    Science.gov (United States)

    Prasad, Lakshman; Swaminarayan, Sriram

    2013-04-23

    A method for rapid hierarchical image segmentation based on perceptually driven contour completion and scene statistics is disclosed. The method begins with an initial fine-scale segmentation of an image, such as obtained by perceptual completion of partial contours into polygonal regions using region-contour correspondences established by Delaunay triangulation of edge pixels as implemented in VISTA. The resulting polygons are analyzed with respect to their size and color/intensity distributions and the structural properties of their boundaries. Statistical estimates of granularity of size, similarity of color, texture, and saliency of intervening boundaries are computed and formulated into logical (Boolean) predicates. The combined satisfiability of these Boolean predicates by a pair of adjacent polygons at a given segmentation level qualifies them for merging into a larger polygon representing a coarser, larger-scale feature of the pixel image and collectively obtains the next level of polygonal segments in a hierarchy of fine-to-coarse segmentations. The iterative application of this process precipitates textured regions as polygons with highly convolved boundaries and helps distinguish them from objects which typically have more regular boundaries. The method yields a multiscale decomposition of an image into constituent features that enjoy a hierarchical relationship with features at finer and coarser scales. This provides a traversable graph structure from which feature content and context in terms of other features can be derived, aiding in automated image understanding tasks. The method disclosed is highly efficient and can be used to decompose and analyze large images.

  8. Early verb constructions in French: adjacency on the left edge.

    Science.gov (United States)

    Veneziano, Edy; Clark, Eve V

    2016-11-01

    Children acquiring French elaborate their early verb constructions by adding adjacent morphemes incrementally at the left edge of core verbs. This hypothesis was tested with 2657 verb uses from four children between 1;3 and 2;7. Consistent with the Adjacency Hypothesis, children added clitic subjects first only to present tense forms (as in il saute 'he jumps'); modals to infinitives (as in faut sauter 'has to jump'); and auxiliaries to past participles (as in a sauté 'has jumped'). Only after this did the children add subjects to the left of a modal or auxiliary, as in elle veut sauter 'she wants to jump', or elle a sauté 'she has jumped'. The order in which these elements were added, and the development in the frequencies of the constructions, all support the predictions of the Adjacency Hypothesis for left edge development in early verb constructions.

  9. Laplacian versus adjacency matrix in quantum walk search

    Science.gov (United States)

    Wong, Thomas G.; Tarrataca, Luís; Nahimov, Nikolay

    2016-10-01

    A quantum particle evolving by Schrödinger's equation contains, from the kinetic energy of the particle, a term in its Hamiltonian proportional to Laplace's operator. In discrete space, this is replaced by the discrete or graph Laplacian, which gives rise to a continuous-time quantum walk. Besides this natural definition, some quantum walk algorithms instead use the adjacency matrix to effect the walk. While this is equivalent to the Laplacian for regular graphs, it is different for non-regular graphs and is thus an inequivalent quantum walk. We algorithmically explore this distinction by analyzing search on the complete bipartite graph with multiple marked vertices, using both the Laplacian and adjacency matrix. The two walks differ qualitatively and quantitatively in their required jumping rate, runtime, sampling of marked vertices, and in what constitutes a natural initial state. Thus the choice of the Laplacian or adjacency matrix to effect the walk has important algorithmic consequences.

  10. Variability of surface velocity in the Kuroshio Current and adjacent waters derived from Argos drifter buoys and satellite altimeter data

    Institute of Scientific and Technical Information of China (English)

    MA Chao; WU Dexing; LIN Xiaopei

    2009-01-01

    By combining Argos drifter buoys and TOPEX/POSEIDON altimeter data, the time series of sea-surface velocity fields in the Kuroshio Current (KC) and adjacent regions are established. And the variability of the KC from the Luzon Strait to the Tokara Strait is studied based on the velocity fields. The results show that the dominant variability period varies in different segments of the KC" The primary period near the Luzon Strait and to the east of Taiwan Island is the intra-seasonal time scale; the KC on the continental shelf of the ECS is the steadiest segment without obvious periodicity, while the Tokara Strait shows the period of seasonal variability. The diverse periods are caused by the Rossby waves propagating from the interior ocean, with adjustments in topography of island chain and local wind stress.

  11. Emission of pesticides during drilling and deposition in adjacent areas

    Directory of Open Access Journals (Sweden)

    Heimbach, Udo

    2014-02-01

    Full Text Available In seven experiments seeds of maize, oil seed rape and barley, treated with neonicotinoids, were sown using pneumatic drilling equipment with deflectors attached in case of pneumatic suction systems. Directly adjacent to the drilled area of usually about 50 m width were replicated areas with bare soil as well as with crops. During maize (Zea mays drilling flowering oil seed rape (Brassica napus and during drilling of barley (Hordeum vulgare and oil seed rape flowering white mustard (Sinapis alba was adjacent. The amount of residues in the adjacent non crop areas in Petri dishes being distributed on the bare soil declined only slowly from 1 to 20 m distance from the area drilled. Seed batches with more abrasion and higher content of active substances in the dust resulted in higher residues off crop. After drilling of maize in four experiments in Petri dishes in adjacent non crop areas in 1-5 m distance between 0.02 and 0.40 g a.s./ha of neonicotinoids and in the adjacent oil seed rape a total of 0.05–0.80 g a.s./ha were detected. After drilling oil seed rape or barley these values were only 0.02–0.06 g a.s./ha in Petri dishes in non crop areas and 0.03-0.08 g a.s./ha in total in adjacent white mustard. In gauze net samplers installed vertically in 3 m distance in non crop areas up to seven times higher values were detected compared to Petri dishes.

  12. White matter pathology in sporadic frontotemporal lobar degeneration with TDP-43 proteinopathy.

    Science.gov (United States)

    Armstrong, Richard A

    To characterize white matter pathology in frontotemporal lobar degeneration (FTLD) with TDP-43 proteinopathy (FTLD-TDP) and its relationship to gray matter pathology. Fiber tracts from frontal and temporal lobes of 10 sporadic cases of FTLD and 8 controls. Density and spatial patterns of vacuolation, glial cell nuclei, and glial inclusions (GI) were studied in 4 fiber tracts from each case. Densities of vacuoles but not glial cells were greater in FTLD-TDP than controls. No GI were observed in controls, while in FTLD-TDP, greatest densities of GI were observed in the cortex of early-onset cases. Vacuoles, glial cell nuclei, and GI were distributed in clusters which were regularly distributed across the tract. Densities of vacuoles in white matter were positively correlated with those in adjacent gray matter, and correlations were also present between GI in white matter and TDP-43-immunoreactive pathology in gray matter. (1) Degeneration of white matter in sporadic FTLD-TDP was characterized by increased vacuolation and GI, (2) pathological changes were topographically distributed, which suggests propagation of pathological TDP-43 in specific groups of fibers, and (3) both white matter pathology and gray matter pathology need to be considered to quantify the pathological "load" in FTLD-TDP.
.

  13. Nonlinear spin wave coupling in adjacent magnonic crystals

    Energy Technology Data Exchange (ETDEWEB)

    Sadovnikov, A. V., E-mail: sadovnikovav@gmail.com; Nikitov, S. A. [Laboratory “Metamaterials,” Saratov State University, Saratov 410012 (Russian Federation); Kotel' nikov Institute of Radioengineering and Electronics, Russian Academy of Sciences, Moscow 125009 (Russian Federation); Beginin, E. N.; Morozova, M. A.; Sharaevskii, Yu. P.; Grishin, S. V.; Sheshukova, S. E. [Laboratory “Metamaterials,” Saratov State University, Saratov 410012 (Russian Federation)

    2016-07-25

    We have experimentally studied the coupling of spin waves in the adjacent magnonic crystals. Space- and time-resolved Brillouin light-scattering spectroscopy is used to demonstrate the frequency and intensity dependent spin-wave energy exchange between the side-coupled magnonic crystals. The experiments and the numerical simulation of spin wave propagation in the coupled periodic structures show that the nonlinear phase shift of spin wave in the adjacent magnonic crystals leads to the nonlinear switching regime at the frequencies near the forbidden magnonic gap. The proposed side-coupled magnonic crystals represent a significant advance towards the all-magnonic signal processing in the integrated magnonic circuits.

  14. Irregular Segmented Region Compression Coding Based on Pulse Coupled Neural Network

    Institute of Scientific and Technical Information of China (English)

    MA Yi-de; QI Chun-liang; QIAN Zhi-bai; SHI Fei; ZHANG Bei-dou

    2006-01-01

    An irregular segmented region coding algorithm based on pulse coupled neural network(PCNN) is presented. PCNN has the property of pulse-coupled and changeable threshold, through which these adjacent pixels with approximate gray values can be activated simultaneously. One can draw a conclusion that PCNN has the advantage of realizing the regional segmentation, and the details of original image can be achieved by the parameter adjustment of segmented images, and at the same time, the trivial segmented regions can be avoided. For the better approximation of irregular segmented regions, the Gram-Schmidt method, by which a group of orthonormal basis functions is constructed from a group of linear independent initial base functions, is adopted. Because of the orthonormal reconstructing method, the quality of reconstructed image can be greatly improved and the progressive image transmission will also be possible.

  15. Segmented Target Design

    Science.gov (United States)

    Merhi, Abdul Rahman; Frank, Nathan; Gueye, Paul; Thoennessen, Michael; MoNA Collaboration

    2013-10-01

    A proposed segmented target would improve decay energy measurements of neutron-unbound nuclei. Experiments like this have been performed at the National Superconducting Cyclotron Laboratory (NSCL) located at Michigan State University. Many different nuclei are produced in such experiments, some of which immediately decay into a charged particle and neutron. The charged particles are bent by a large magnet and measured by a suite of charged particle detectors. The neutrons are measured by the Modular Neutron Array (MoNA) and Large Multi-Institutional Scintillation Array (LISA). With the current target setup, a nucleus in a neutron-unbound state is produced with a radioactive beam impinged upon a beryllium target. The resolution of these measurements is very dependent on the target thickness since the nuclear interaction point is unknown. In a segmented target using alternating layers of silicon detectors and Be-targets, the Be-target in which the nuclear reaction takes place would be determined. Thus the experimental resolution would improve. This poster will describe the improvement over the current target along with the status of the design. Work supported by Augustana College and the National Science Foundation grant #0969173.

  16. Segmentation of the Infant Food Market

    OpenAIRE

    Hrůzová, Daniela

    2015-01-01

    The theoretical part covers general market segmentation, namely the marketing importance of differences among consumers, the essence of market segmentation, its main conditions and the process of segmentation, which consists of four consecutive phases - defining the market, determining important criteria, uncovering segments and developing segment profiles. The segmentation criteria, segmentation approaches, methods and techniques for the process of market segmentation are also described in t...

  17. Segmentation of the Infant Food Market

    OpenAIRE

    Hrůzová, Daniela

    2015-01-01

    The theoretical part covers general market segmentation, namely the marketing importance of differences among consumers, the essence of market segmentation, its main conditions and the process of segmentation, which consists of four consecutive phases - defining the market, determining important criteria, uncovering segments and developing segment profiles. The segmentation criteria, segmentation approaches, methods and techniques for the process of market segmentation are also described in t...

  18. Biochemical Measurements of Free Opsin in Macular Degeneration Eyes: Examining the 11-CIS Retinal Deficiency Hypothesis of Delayed Dark Adaptation (An American Ophthalmological Society Thesis).

    Science.gov (United States)

    Hanneken, Anne; Neikirk, Thomas; Johnson, Jennifer; Kono, Masahiro

    2017-08-01

    To test the hypothesis that delayed dark adaptation in patients with macular degeneration is due to an excess of free unliganded opsin (apo-opsin) and a deficiency of the visual chromophore, 11-cis retinal, in rod outer segments. A total of 50 human autopsy eyes were harvested from donors with and without macular degeneration within 2-24 hrs. postmortem. Protocols were developed which permitted dark adaptation of normal human eyes after death and enucleation. Biochemical methods of purifying rod outer segments were optimized and the concentration of rhodopsin and apo-opsin was measured with UV-visible scanning spectroscopy. The presence of apo-opsin was calculated by measuring the difference in the rhodopsin absorption spectra before and after the addition of 11-cis retinal. A total of 20 normal eyes and 16 eyes from donors with early, intermediate and advanced stages of macular degeneration were included in the final analysis. Dark adaptation was achieved by harvesting whole globes in low light, transferring into dark (light-proof) canisters and dissecting the globes using infrared light and image converters for visualization. Apo-opsin was readily detected in positive controls after the addition of 11-cis retinal. Normal autopsy eyes showed no evidence of apo-opsin. Eyes with macular degeneration also showed no evidence of apo-opsin, regardless of the severity of disease. Methods have been developed to study dark adaptation in human autopsy eyes. Eyes with age-related macular degeneration do not show a deficiency of 11-cis retinal or an excess of apo-opsin within rod outer segments.

  19. New treatment strategies for canine intervertebral disc degeneration

    NARCIS (Netherlands)

    Smolders, L.A.

    2013-01-01

    Degeneration of the intervertebral disc (IVD) is a common problem in dogs and humans. IVD degeneration can lead to herniation of the IVD with subsequent compression of neural structures and various clinical signs, including back pain. Current treatment of IVD disease is conservative or surgical. How

  20. Impulse Observability and Impulse Controllability of Regular Degenerate Evolution Systems

    Institute of Scientific and Technical Information of China (English)

    GE Zhaoqiang

    2016-01-01

    Impulse observability and impulse controllability of regular degenerate evolution systems are discussed by using functional analysis and operator theory in Banach space.Necessary and sufficient conditions for the impulse observability and impulse controllability of the system are obtained.This research is theoretically important for studying the design of the degenerate evolution system.

  1. Non-autonomous Degenerate KdV Systems

    OpenAIRE

    Turhan, Refik

    2002-01-01

    Non-autonomous degenerate KdV systems in (1+1) dimensions are considered for integrability classification. Integrability of the systems is associated with the existence of a recursion operator. Some new non-autonomous degenerate two-component KdV systems are found.

  2. Delivery systems for the treatment of degenerated intervertebral discs

    NARCIS (Netherlands)

    Blanquer, S.B.G.; Grijpma, D.W.; Poot, A.A.

    2015-01-01

    The intervertebral disc (IVD) is the most avascular and acellular tissue in the body and therefore prone to degeneration. During IVD degeneration, the balance between anabolic and catabolic processes in the disc is deregulated, amongst others leading to alteration of extracellular matrix production,

  3. Demonstration of Degenerate Vector Phase-Sensitive Amplification

    OpenAIRE

    Riesgo, A.L.; Karlsson, M.; Lundstrm, C.; Andrekson, P. A.

    2013-01-01

    The performance of a degenerate vector (dual cross-polarized pump) phase-sensitive amplifier (PSA) is characterized and compared to a degenerate scalar (dual co-polarized pump) PSA. In both schemes, we assess the gain as a function of the signal state of polarization, verifying its compliance with theory, and the phase transfer function. PSOPA

  4. Long-term Analysis of Degenerate Parabolic Equations in RN

    Institute of Scientific and Technical Information of China (English)

    Gao Cheng YUE; Cheng Kui ZHONG

    2015-01-01

    Longtime behavior of degenerate equations with the nonlinearity of polynomial growth of arbitrary order on the whole space RN is considered. By using ?-trajectories methods, we proved that weak solutions generated by degenerate equations possess an (L2U (RN ), L2loc(RN ))-global attractor. Moreover, the upper bounds of the Kolmogorovε-entropy for such global attractor are also obtained.

  5. 9 CFR 311.35 - Muscular inflammation, degeneration, or infiltration.

    Science.gov (United States)

    2010-01-01

    ... 9 Animals and Animal Products 2 2010-01-01 2010-01-01 false Muscular inflammation, degeneration, or infiltration. 311.35 Section 311.35 Animals and Animal Products FOOD SAFETY AND INSPECTION SERVICE... PARTS § 311.35 Muscular inflammation, degeneration, or infiltration. (a) If muscular lesions are...

  6. Delivery systems for the treatment of degenerated intervertebral discs

    NARCIS (Netherlands)

    Blanquer, S. B. G.; Grijpma, D. W.; Poot, A. A.

    2015-01-01

    The intervertebral disc (ND) is the most avascular and acellular tissue in the body and therefore prone to degeneration. During IVD degeneration, the balance between anabolic and catabolic processes in the disc is deregulated, amongst others leading to alteration of extracellular matrix production,

  7. Prevalence of age-related macular degeneration in elderly Caucasians

    DEFF Research Database (Denmark)

    Erke, Maja G; Bertelsen, Geir; Peto, Tunde;

    2012-01-01

    To describe the sex- and age-specific prevalence of drusen, geographic atrophy, and neovascular age-related macular degeneration (AMD).......To describe the sex- and age-specific prevalence of drusen, geographic atrophy, and neovascular age-related macular degeneration (AMD)....

  8. Conjunctival spheroid degeneration. Recurrence after excision.

    Science.gov (United States)

    Norn, M S

    1982-06-01

    After excision of part of the conjunctiva in 15 eyes (14 subjects) due to spheroid degeneration, the author noticed only fairly small, varying numbers of autofluorescent and colourless spheroids-after an observation period of 18 months, only 6% of autofluorescent and 13% of colourless bodies were observed compared to the number before biopsy. Around the biopsy site only a few spheroids were seen, with a non-significant tendency to increase in number of the colourless bodies. In the cornea the band-shaped keratopathy had aggravated, with the formation of a small number of large, autofluorescent spheroids. A pinguecula recurred in a mild degree only in 3 out of 13 cases within 18 months.

  9. Degenerate Neutrinos in Left Right Symmetric Theory

    CERN Document Server

    Joshipura, A S

    1995-01-01

    Various hints on the neutrino masses namely, ({\\em i}) the solar neutrino deficit ({\\em ii}) the atmospheric neutrino deficit ({\\em iii}) the need for the dark matter and/or ({\\em iv}) the non-zero neutrinoless double beta decay collectively imply that all the three neutrinos must be nearlty degenerate. This feature can be understood in the left right symmetric theory. We present a model based on the group $SU(2)_{L}\\times SU(2)_R\\times U(1)_{B-L}\\times SU(2)_H$ which can explain the required departures from degeneracy in neutrino masses and large mixing among them without assuming any of the mixing in the quark or charged lepton sector to be large as would be expected in a typical $SO(10)$ model.

  10. Frequency metrology in quantum degenerate helium

    Directory of Open Access Journals (Sweden)

    Vassen Wim

    2013-08-01

    Full Text Available We have measured the absolute frequency of the 1557-nm doubly forbidden transition between the two metastable states of helium, 2 3S1 (lifetime 8000 s and 2 1S0 (lifetime 20 ms, with 1 kHz precision. With an Einstein coefficient of 10−7 s−1 this is one of weakest optical transitions ever measured. The measurement was performed in a Bose-Einstein condensate of 4He* as well as in a Degenerate Fermi Gas of 3He*, trapped in a crossed dipole trap. From the isotope shift we deduced the nuclear charge radius difference between the α-particle and the helion. Our value differs by 4σ with a very recent result obtained on the 2 3S → 2 3P transition.

  11. [Climate, brain, and degeneration in Cabanis].

    Science.gov (United States)

    Caponi, Sandra

    2009-01-01

    This analysis of the arguments defended by Cabanis in "Rapports du physique et du moral de l'homme" takes as its point of departure his eighth and ninth Memoirs, which focus on analyzing the influences of regime and climate. These writings afford a new reading of the arguments Cabanis used to explain the relation between the physical traits and moral habits of individuals and races. The article analyzes his debts to natural history, especially Buffon's theory of degeneration; to the Hippocratic tradition, above all the humor theory; and to studies of brain anatomy and pathology. Lastly, it examines the role that the human and moral sciences of medicine and hygiene play in the regeneration of the human species.

  12. Bmi-1 absence causes premature brain degeneration.

    Directory of Open Access Journals (Sweden)

    Guangliang Cao

    Full Text Available Bmi-1, a polycomb transcriptional repressor, is implicated in cell cycle regulation and cell senescence. Its absence results in generalized astrogliosis and epilepsy during the postnatal development, but the underlying mechanisms are poorly understood. Here, we demonstrate the occurrence of oxidative stress in the brain of four-week-old Bmi-1 null mice. The mice showed various hallmarks of neurodegeneration including synaptic loss, axonal demyelination, reactive gliosis and brain mitochondrial damage. Moreover, astroglial glutamate transporters and glutamine synthetase decreased in the Bmi-1 null hippocampus, which might contribute to the sporadic epileptic-like seizures in these mice. These results indicate that Bmi-1 is required for maintaining endogenous antioxidant defenses in the brain, and its absence subsequently causes premature brain degeneration.

  13. A computational model of motor neuron degeneration.

    Science.gov (United States)

    Le Masson, Gwendal; Przedborski, Serge; Abbott, L F

    2014-08-20

    To explore the link between bioenergetics and motor neuron degeneration, we used a computational model in which detailed morphology and ion conductance are paired with intracellular ATP production and consumption. We found that reduced ATP availability increases the metabolic cost of a single action potential and disrupts K+/Na+ homeostasis, resulting in a chronic depolarization. The magnitude of the ATP shortage at which this ionic instability occurs depends on the morphology and intrinsic conductance characteristic of the neuron. If ATP shortage is confined to the distal part of the axon, the ensuing local ionic instability eventually spreads to the whole neuron and involves fasciculation-like spiking events. A shortage of ATP also causes a rise in intracellular calcium. Our modeling work supports the notion that mitochondrial dysfunction can account for salient features of the paralytic disorder amyotrophic lateral sclerosis, including motor neuron hyperexcitability, fasciculation, and differential vulnerability of motor neuron subpopulations.

  14. LOCKING-FREE DEGENERATED ISOPARAMETRIC SHELL ELEMENT

    Institute of Scientific and Technical Information of China (English)

    章向明; 王安稳; 何汉林

    2001-01-01

    An 8-noded locking-free degenerated isoparametric shell element is presented.A revised interpolation for shear strain terms was constructed in natural co-ordinate system such that all necessary modes ( translation, rotation and constant curvature ) are preserved,which can be used to eliminate shear locking. A revised interpolation for membrane strains was produced in the local Cartesian co-ordinate system to overcome membrane locking behavior. The new 8-noded element has the proper rank, with the requisite number of zero eigenvalues each associated with a rigid mode. The element does not exhibit membrane or shear locking for large span-thickness ratio. The element does not form element mechanisms or extra spurious zero energy modes. Therefore, it can be used for both thin and thick shells.

  15. Neuropathology of frontotemporal lobar degeneration: A review

    Directory of Open Access Journals (Sweden)

    Valéria Santoro Bahia

    Full Text Available ABSTRACT Frontotemporal lobar degeneration (FTLD is the second most common cause of presenile dementia. Three main clinical variants are widely recognized within the FTLD spectrum: the behavioural variant of frontotemporal dementia (bvFTD, semantic dementia (SD and progressive non-fluent aphasia (PNFA. FTLD represents a highly heterogeneous group of neurodegenerative disorders which are best classified according to the main protein component of pathological neuronal and glial inclusions. The most common pathological class of FTLD is associated with the TDP-43 protein (FTLD-TDP, while FTLD-Tau is considered slightly less common while the FTLD-FUS (Fused in sarcoma protein pathology is rare. In this review, these three major pathological types of FTLD are discussed.

  16. Output radiation from a degenerate parametric oscillator

    CERN Document Server

    Tesfa, S

    2007-01-01

    We study the squeezing as well as the statistical properties of the output radiation from a degenerate parametric oscillator coupled to a squeezed vacuum reservoir employing the stochastic differential equations associated with the normal ordering. It is found that the degree of squeezing of the output radiation is less than the corresponding cavity radiation. However, for output radiation the correlation of the quadrature operators evaluated at different times also exhibits squeezing, which is the reason for quenching of the overall noise in one of the quadrature components of the squeezing spectrum even when the oscillator is coupled to a vacuum reservoir. Moreover, coupling the oscillator to the squeezed vacuum reservoir enhances the squeezing exponentially and it also increases the mean photon number.

  17. Nearly degenerate neutrinos, Supersymmetry and radiative corrections

    CERN Document Server

    Casas, J A; Ibarra, Alejandro; Navarro, I

    2000-01-01

    If neutrinos are to play a relevant cosmological role, they must be essentially degenerate with a mass matrix of the bimaximal mixing type. We study this scenario in the MSSM framework, finding that if neutrino masses are produced by a see-saw mechanism, the radiative corrections give rise to mass splittings and mixing angles that can accommodate the atmospheric and the (large angle MSW) solar neutrino oscillations. This provides a natural origin for the $\\Delta m^2_{sol} << \\Delta m^2_{atm}$ hierarchy. On the other hand, the vacuum oscillation solution to the solar neutrino problem is always excluded. We discuss also in the SUSY scenario other possible effects of radiative corrections involving the new neutrino Yukawa couplings, including implications for triviality limits on the Majorana mass, the infrared fixed point value of the top Yukawa coupling, and gauge coupling and bottom-tau unification.

  18. CEMAsuite: open source degenerate PCR primer design.

    Science.gov (United States)

    Lane, Courtney E; Hulgan, Daniel; O'Quinn, Kelly; Benton, Michael G

    2015-11-15

    The codon-equivalent multiple alignment suite begins conservational analysis for polymerase chain reaction primer design at the protein level, allowing the user to design consensus primers capable of detecting homologous coding sequences even when low-to-moderate sequence information is available. This package also condenses the wealth of information associated with multiple sequence alignments and presents them in an intuitive manner, allowing the user to quickly and effectively address degenerate primer design considerations. https://sourceforge.net/projects/cemasuite/. benton@lsu.edu or cemasuite@gmail.com Supplementary data are available at Bioinformatics online. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  19. Progression of Fatty Muscle Degeneration in Atraumatic Rotator Cuff Tears.

    Science.gov (United States)

    Hebert-Davies, Jonah; Teefey, Sharlene A; Steger-May, Karen; Chamberlain, Aaron M; Middleton, William; Robinson, Kathryn; Yamaguchi, Ken; Keener, Jay D

    2017-05-17

    The purpose of this prospective study was to examine the progression of fatty muscle degeneration over time in asymptomatic shoulders with degenerative rotator cuff tears. Subjects with an asymptomatic rotator cuff tear in 1 shoulder and pain due to rotator cuff disease in the contralateral shoulder were enrolled in a prospective cohort. Subjects were followed annually with shoulder ultrasonography, which evaluated tear size, location, and fatty muscle degeneration. Tears that were either full-thickness at enrollment or progressed to a full-thickness defect during follow-up were examined. A minimum follow-up of 2 years was necessary for eligibility. One hundred and fifty-six shoulders with full-thickness rotator cuff tears were potentially eligible. Seventy shoulders had measurable fatty muscle degeneration of at least 1 rotator cuff muscle at some time point. Patients with fatty muscle degeneration in the shoulder were older than those without degeneration (mean, 65.8 years [95% confidence interval (CI), 64.0 to 67.6 years] compared with 61.0 years [95% CI, 59.1 to 62.9 years]; p tears at baseline was larger in shoulders with degeneration than in shoulders that did not develop degeneration (13 and 10 mm wide, respectively, and 13 and 10 mm long; p Tears with fatty muscle degeneration were more likely to have enlarged during follow-up than were tears that never developed muscle degeneration (79% compared with 58%; odds ratio, 2.64 [95% CI, 1.29 to 5.39]; p muscle degeneration occurred more frequently in shoulders with tears that had enlarged (43%; 45 of 105) than in shoulders with tears that had not enlarged (20%; 10 of 51; p tears with enlargement and progression of muscle degeneration were more likely to extend into the anterior supraspinatus than were those without progression (53% and 17%, respectively; p tear size (p = 0.56). The median time from tear enlargement to progression of fatty muscle degeneration was 1.0 year (range, -2.0 to 6.9 years) for the

  20. CONTROLLABILITY OF DELAY DEGENERATE CONTROL SYSTEMS WITH INDEPENDENT SUBSYSTEMS

    Institute of Scientific and Technical Information of China (English)

    蒋威

    2003-01-01

    The controllability of delay degenerate differential control systems is discussed. Firstly, delay degenerate differential control system was transformed to be canonical form, and the connected terms were gotten rid of, had delay degenerate differential control systems with independent subsystems. For the general delay degenerate differnetial control systems, it was gotten that the necessary and sufficient condition of that they are controllable is that their reachable set is equal to the whole space For the delay degenerate differential control systems with independent subsystems, it was gotten that the necessary and sufficient conditions of that they are controllable are that their reachable sets are equal to their corresponding subspaces. Then some algebra criteria were gotten. Finally, an example was given to illustrate the main results.

  1. Formation of Degenerate Band Gaps in Layered Systems

    Directory of Open Access Journals (Sweden)

    Alexey P. Vinogradov

    2012-06-01

    Full Text Available In the review, peculiarities of spectra of one-dimensional photonic crystals made of anisotropic and/or magnetooptic materials are considered. The attention is focused on band gaps of a special type—the so called degenerate band gaps which are degenerate with respect to polarization. Mechanisms of formation and properties of these band gaps are analyzed. Peculiarities of spectra of photonic crystals that arise due to the linkage between band gaps are discussed. Particularly, it is shown that formation of a frozen mode is caused by linkage between Brillouin and degenerate band gaps. Also, existence of the optical Borrmann effect at the boundaries of degenerate band gaps and optical Tamm states at the frequencies of degenerate band gaps are analyzed.

  2. Hoelder Continuity for Solutions of Degenerate Parabolic Equation with Two Degenerate Points

    Institute of Scientific and Technical Information of China (English)

    刘建中; 李育生; 等

    1993-01-01

    In this paper we discuss the quasilinear parabolic equation Ut=△↓(uα(1-u)β.△↓u)+B(x,t,u)△↓u+C(x,t,u)which is degenerate at u=0 and u=1.Let u(x,t)be a weak solution of the equation satisfying 0

  3. Migration of PCBs from Sealants to Adjacent Material

    DEFF Research Database (Denmark)

    Andersen, Helle Vibeke; Gunnarsen, Lars Bo; Kampmann, Kristoffer

    2015-01-01

    adjacent to outdoor PCB-containing sealants. The samples were submitted to the laboratory for normal commercial assessment of PCB content in relation to the handling of waste from renovation works in Denmark. The results showed that the PBC concentration in the sealant not necessarily relate...

  4. Flow and edge scour in current adjacent to stone covers

    DEFF Research Database (Denmark)

    Petersen, Thor U.; Sumer, B. Mutlu; Bøgelund, Jon;

    2015-01-01

    This paper presents the results of an experimental investigation on edge scour adjacent to a stone cover laid on a sandy bed. The three-dimensional flow over the edge of the stone layer has been investigated by the use of particle image velocimetry. The flow measurements show a significant amount...

  5. Measurement Methods to Determine Air Leakage Between Adjacent Zones

    Energy Technology Data Exchange (ETDEWEB)

    Hult, Erin L. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Dickerhoff, Darryl J. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Price, Phillip N. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2012-09-01

    Air leakage between adjacent zones of a building can lead to indoor air quality and energy efficiency concerns, however there is no existing standard for measuring inter-zonal leakage. In this study, synthesized data and field measurements are analyzed in order to explore the uncertainty associated with different methods for collecting and analyzing fan pressurization measurements to calculate interzone leakage.

  6. Segmented heat exchanger

    Science.gov (United States)

    Baldwin, Darryl Dean; Willi, Martin Leo; Fiveland, Scott Byron; Timmons, Kristine Ann

    2010-12-14

    A segmented heat exchanger system for transferring heat energy from an exhaust fluid to a working fluid. The heat exchanger system may include a first heat exchanger for receiving incoming working fluid and the exhaust fluid. The working fluid and exhaust fluid may travel through at least a portion of the first heat exchanger in a parallel flow configuration. In addition, the heat exchanger system may include a second heat exchanger for receiving working fluid from the first heat exchanger and exhaust fluid from a third heat exchanger. The working fluid and exhaust fluid may travel through at least a portion of the second heat exchanger in a counter flow configuration. Furthermore, the heat exchanger system may include a third heat exchanger for receiving working fluid from the second heat exchanger and exhaust fluid from the first heat exchanger. The working fluid and exhaust fluid may travel through at least a portion of the third heat exchanger in a parallel flow configuration.

  7. Schizophrenia as segmental progeria

    Science.gov (United States)

    Papanastasiou, Evangelos; Gaughran, Fiona; Smith, Shubulade

    2011-01-01

    Schizophrenia is associated with a variety of physical manifestations (i.e. metabolic, neurological) and despite psychotropic medication being blamed for some of these (in particular obesity and diabetes), there is evidence that schizophrenia itself confers an increased risk of physical disease and early death. The observation that schizophrenia and progeroid syndromes share common clinical features and molecular profiles gives rise to the hypothesis that schizophrenia could be conceptualized as a whole body disorder, namely a segmental progeria. Mammalian cells employ the mechanisms of cellular senescence and apoptosis (programmed cell death) as a means to control inevitable DNA damage and cancer. Exacerbation of those processes is associated with accelerated ageing and schizophrenia and this warrants further investigation into possible underlying biological mechanisms, such as epigenetic control of the genome. PMID:22048679

  8. Probabilistic retinal vessel segmentation

    Science.gov (United States)

    Wu, Chang-Hua; Agam, Gady

    2007-03-01

    Optic fundus assessment is widely used for diagnosing vascular and non-vascular pathology. Inspection of the retinal vasculature may reveal hypertension, diabetes, arteriosclerosis, cardiovascular disease and stroke. Due to various imaging conditions retinal images may be degraded. Consequently, the enhancement of such images and vessels in them is an important task with direct clinical applications. We propose a novel technique for vessel enhancement in retinal images that is capable of enhancing vessel junctions in addition to linear vessel segments. This is an extension of vessel filters we have previously developed for vessel enhancement in thoracic CT scans. The proposed approach is based on probabilistic models which can discern vessels and junctions. Evaluation shows the proposed filter is better than several known techniques and is comparable to the state of the art when evaluated on a standard dataset. A ridge-based vessel tracking process is applied on the enhanced image to demonstrate the effectiveness of the enhancement filter.

  9. [ANALYSIS OF COMPLICATIONS POSTOPERATIVE CAUSES AND MORTALITY AFTER RADICAL TREATMENT FOR TUMORS OF THE LEFT ANATOMICAL SEGMENT OF THE PANCREAS].

    Science.gov (United States)

    Kopchak, V M; Kopchak, K V; Khomyak, I V; Duvalko, O V; Tkachuk, O S; Andronik, S V; Shevkolenko, H H; Khanenko, V V; Kvasivka, O O; Zubkov, O O

    2015-07-01

    Radical surgery for tumors of the left anatomical and surgical segment of the pancreas proved for distal resection in various versions, central resection and enucleation of tumors. The causes of early postoperative complications and mortality in 129 patients aged from 14 to 81 years, operated on for neoplastic lesions of the left anatomical segment of the pancreas in the period from 2009 to 2014 were analysed. The influence of various factors of risk of complications and mortality were studied in particular, extended resection, for tumor invasion of adjacent organs, and adjacent vessels.

  10. Impact of stretching-segment on saturated flow rate of signalized intersection using cellular automation

    Institute of Scientific and Technical Information of China (English)

    李岩; 陈宽民; 过秀成

    2013-01-01

    In order to analyze the impact of stretching-segment on the saturated flow rate of signalized intersection approach, an improved cellular automation model was proposed to estimate its saturated flow rate. The NaSch model was improved by adding different slow probabilities, turning deceleration rules and modified lane changing rules. The relationship between the saturated flow rate of stretching-segments and adjacent lanes was tested in numerical simulation. The length of stretching-segment, cycle length and green time were selected as impact factors of the cellular automation model. The simulation result indicates that the geometrics design of stretching-segment and the traffic signal timing scenario have major effects on the saturated flow rate of the intersection approach. The saturated flow rate will continually increase with increasing stretching-segment length until it reaches a threshold. After reaching the threshold, the stretching-segment can be treated as a separate lane. The green time is approximately linearly related to the threshold length of the stretching-segment. An optimum cycle length exists when the length of the stretching-segment is not long enough, and it is approximately linearly related to the length of stretching-segment.

  11. Automated medical image segmentation techniques

    Directory of Open Access Journals (Sweden)

    Sharma Neeraj

    2010-01-01

    Full Text Available Accurate segmentation of medical images is a key step in contouring during radiotherapy planning. Computed topography (CT and Magnetic resonance (MR imaging are the most widely used radiographic techniques in diagnosis, clinical studies and treatment planning. This review provides details of automated segmentation methods, specifically discussed in the context of CT and MR images. The motive is to discuss the problems encountered in segmentation of CT and MR images, and the relative merits and limitations of methods currently available for segmentation of medical images.

  12. Early developed ASD (adjacent segmental disease) in patients after surgical treatment of the spine due to cancer metastases.

    Science.gov (United States)

    Guzik, Grzegorz

    2017-05-12

    The causes of ASD are still relatively unknown. Correlation between clinical status of patients and radiological MRI findings is of primary importance. The radiological classifications proposed by Pfirmann and Oner are most commonly used to assess intradiscal degenerative changes. The aim of the study was to assess the influence of the extension of spine fixation on the risk of developing ASD in a short time after surgery. A total of 332 patients with spinal tumors were treated in our hospital between 2010 and 2013. Of these patients, 287 underwent surgeries. A follow-up MRI examination was performed 12 months after surgical treatment. The study population comprised of 194 patients. Among metastases, breast cancer was predominant (29%); neurological deficits were detected in 76 patients. Metastases were seen in the thoracic (45%) and lumbar (30%) spine; in 25% of cases, they were of multisegmental character. Pathological fractures concerned 88% of the patients. Statistical calculations were made using the χ2 test. Statistical analysis was done using the Statistica v. 10 software. A p value ASD were noted in only seven patients. Two patients had symptoms of nerve root irritation in the lumbar spine. Twenty-two patients (11%) were diagnosed with ASD according to the MRI classifications by Oner, Rijt, and Ramos, while the more sensitive Pfirmann classification allowed to detect the disease in 46 patients (24%). Healthy or almost healthy discs of Oner type I correlated with the criteria of Pfirmann types II and III. The percentage of the incidence of ASD diagnosed 1 year after the surgery using the Pfirmann classifications was significantly higher than diagnosed according to the clinical examination. The incidence of ASD in patients after spine surgeries due to cancer metastases does not differ between the study groups. ASD detectability based on clinical signs is significantly lower than ASD detectability based on MR images according to the system by Pfirrmann et.al. ASD risk increase among patients with multilevel fixation.

  13. A model of stress-induced geometrical remodeling of vessel segments adjacent to stents and artery/graft anastomoses.

    Science.gov (United States)

    Rachev, A; Manoach, E; Berry, J; Moore, J E

    2000-10-07

    The mismatch between the elastic properties and initial geometry of a host artery and an implanted stent or graft cause significant stress concentration at the zones close to junctions. This may contribute to the often observed intimal hyperplasia, resulting in late lumen loss and eventual restenosis. This study proposes a mathematical model for stress-induced thickening of the arterial wall at the zones close to an implanted stent or graft. The host artery was considered initially as a cylindrical shell with constant thickness that was clamped to the stent or graft, which was assumed to be non-deformable in the circumferential direction. It was assumed that the abnormal circumferential and axial stresses due to the bending of the arterial wall cause wall thickening that tends to restore the stress state close to that existing far from the junction. The linear equations of a cylindrical shell with variable thickness were coupled to an evolution equation for the wall thickness. These equations were solved numerically and a parametric study was performed using finite difference method and explicit time step. The results show that the remodeling process is self-limiting and leads to local thickening that gradually decreases with distance from the edge of the stent/graft. Model predictions were tested against morphological findings existing in the literature. Recommendations on stent designs that reduce stress concentrations are discussed. Copyright 2000 Academic Pr