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Sample records for disc replacement pitfalls

  1. Spine imaging after lumbar disc replacement: pitfalls and current recommendations

    PubMed Central

    Robinson, Yohan; Sandén, Bengt

    2009-01-01

    Background Most lumbar artificial discs are still composed of stainless steel alloys, which prevents adequate postoperative diagnostic imaging of the operated region when using magnetic resonance imaging (MRI). Thus patients with postoperative radicular symptoms or claudication after stainless steel implants often require alternative diagnostic procedures. Methods Possible complications of lumbar total disc replacement (TDR) are reviewed from the available literature and imaging recommendations given with regard to implant type. Two illustrative cases are presented in figures. Results Access-related complications, infections, implant wear, loosening or fracture, polyethylene inlay dislodgement, facet joint hypertrophy, central stenosis, and ankylosis of the operated segment can be visualised both in titanium and stainless steel implants, but require different imaging modalities due to magnetic artifacts in MRI. Conclusion Alternative radiographic procedures should be considered when evaluating patients following TDR. Postoperative complications following lumbar TDR including spinal stenosis causing radiculopathy and implant loosening can be visualised by myelography and radionucleotide techniques as an adjunct to plain film radiographs. Even in the presence of massive stainless steel TDR implants lumbar radicular stenosis and implant loosening can be visualised if myelography and radionuclide techniques are applied. PMID:19619332

  2. Artificial Disc Replacement

    MedlinePlus

    ... treat this condition, alternatives to disc replacement include fusion, nonoperative care or no treatment. Typically, surgery is ... operative treatment for disc pain has been spinal fusion. This is a surgical procedure in which disc ...

  3. Total disc replacement.

    PubMed

    Vital, J-M; Boissière, L

    2014-02-01

    Total disc replacement (TDR) (partial disc replacement will not be described) has been used in the lumbar spine since the 1980s, and more recently in the cervical spine. Although the biomechanical concepts are the same and both are inserted through an anterior approach, lumbar TDR is conventionally indicated for chronic low back pain, whereas cervical TDR is used for soft discal hernia resulting in cervicobrachial neuralgia. The insertion technique must be rigorous, with precise centering in the disc space, taking account of vascular anatomy, which is more complex in the lumbar region, particularly proximally to L5-S1. All of the numerous studies, including prospective randomized comparative trials, have demonstrated non-inferiority to fusion, or even short-term superiority regarding speed of improvement. The main implant-related complication is bridging heterotopic ossification with resulting loss of range of motion and increased rates of adjacent segment degeneration, although with an incidence lower than after arthrodesis. A sufficiently long follow-up, which has not yet been reached, will be necessary to establish definitively an advantage for TDR, particularly in the cervical spine. PMID:24412045

  4. On total disc replacement.

    PubMed

    Berg, Svante

    2011-02-01

    Low back pain consumes a large part of the community's resources dedicated to health care and sick leave. Back disorders also negatively affect the individual leading to pain suffering, decreased quality-of-life and disability. Chronic low back pain (CLBP) due to degenerative disc disease (DDD) is today often treated with fusion when conservative treatment has failed and symptoms are severe. This treatment is as successful as arthroplasty is for hip arthritis in restoring the patient's quality of life and reducing disability. Even so, there are some problems with this treatment, one of these being recurrent CLBP from an adjacent segment (ASD) after primarily successful surgery. This has led to the development of alternative surgical treatments and devices that maintain or restore mobility, in order to reduce the risk for ASD. Of these new devices, the most frequently used are the disc prostheses used in Total Disc Replacement (TDR). This thesis is based on four studies comparing total disc replacement with posterior fusion. The studies are all based on a material of 152 patients with DDD in one or two segments, aged 20-55 years that were randomly treated with either posterior fusion or TDR. The first study concerned clinical outcome and complications. Follow-up was 100% at both one and two years. It revealed that both treatment groups had a clear benefit from treatment and that patients with TDR were better in almost all outcome scores at one-year follow-up. Fusion patients continued to improve during the second year. At two-year follow-up there was a remaining difference in favour of TDR for back pain. 73% in the TDR group and 63% in the fusion group were much better or totally pain-free (n.s.), while twice as many patients in the TDR group were totally pain free (30%) compared to the fusion group (15%). Time of surgery and total time in hospital were shorter in the TDR group. There was no difference in complications and reoperations, except that seventeen of the

  5. Reoperations Following Cervical Disc Replacement

    PubMed Central

    Skovrlj, Branko; Lee, Dong-Ho; Caridi, John Michael

    2015-01-01

    Cervical disc replacement (CDR) has emerged as an alternative surgical option to cervical arthrodesis. With increasing numbers of patients and longer follow-ups, complications related to the device and/or aging spine are growing, leaving us with a new challenge in the management and surgical revision of CDR. The purpose of this study is to review the current literature regarding reoperations following CDR and to discuss about the approaches and solutions for the current and future potential complications associated with CDR. The published rates of reoperation (mean, 1.0%; range, 0%-3.1%), revision (mean, 0.2%; range, 0%-0.5%), and removal (mean, 1.2%; range, 0%-1.9%) following CDR are low and comparable to the published rates of reoperation (mean, 1.7%; range; 0%-3.4%), revision (mean, 1.5%; range, 0%-4.7%), and removal (mean, 2.0%; range, 0%-3.4%) following cervical arthrodesis. The surgical interventions following CDR range from the repositioning to explantation followed by fusion or the reimplantation to posterior foraminotomy or fusion. Strict patient selection, careful preoperative radiographic review and surgical planning, as well as surgical technique may reduce adverse events and the need for future intervention. Minimal literature and no guidelines exist for the approaches and techniques in revision and for the removal of implants following CDR. Adherence to strict indications and precise surgical technique may reduce the number of reoperations, revisions, and removals following CDR. Long-term follow-up studies are needed, assessing the implant survivorship and its effect on the revision and removal rates. PMID:26097667

  6. Activ C cervical disc replacement for myelopathy

    PubMed Central

    McGonagle, L.; Cadman, S.; Chitgopkar, S. D.; Canavan, L.; O’Malley, M.; Shackleford, I. M.

    2011-01-01

    Background: Cervical disc replacement is becoming an increasingly popular treatment option for cervical myelopathy. It retains motion at the affected segment, unlike anterior cervical discectomy and fusion. The aim of this study is to assess the outcomes of a series of patients who underwent Activ C disc replacement for cervical myelopathy. Materials and Methods: A series of patients at the above Trust with clinical and radiological evidence of cervical myelopathy who were suitable for cervical disc replacement from 2007 to 2009 were included. Implants were inserted by one of two consultant surgeons {IMS, MO’M}. Patients were assessed preoperatively and at six, 12 and 24 months, postoperatively, with a visual analogue score (VAS) for neck and arm pain severity and frequency, the Neck Disability Index questionnaire (NDI) and the Centre for Epidemiologic Studies Depression questionnaire (CES-D). Results: Ten patients underwent surgery between May 2007 and July 2009, 6 women, and 4 men. Average age was 54 years (40-64). Disc levels replaced were: four at C4-5; eight at C5-6; seven at C6-7. Three patients had one disc replaced, five patients had two discs replaced, and two patients had three discs replaced. The VAS for neck pain improved from 5.9 pre-operatively to 1.4-24 months postoperatively and the VAS arm pain improved from 5.4 to 2.6. The NDI improved from 51% preoperatively to 26.8% at 24 months postoperatively. The CES-D showed a slight increase from 19.5 preoperatively to 21.7 at 24 months, postoperatively. Conclusion: Cervical decompression and disc replacement improves pain and function in patients with cervical myelopathy. This benefit is maintained at 24 months post op, with no cases requiring revision. PMID:23125494

  7. Two-level total lumbar disc replacement

    PubMed Central

    Bakaloudis, Georgios; Lolli, Francesco; Vommaro, Francesco; Parisini, Patrizio

    2009-01-01

    Total lumbar disc replacement (TDR) has been widely used as a treatment option for 2-level symptomatic degenerative disc disease. However, recent studies have presented conflicting results and some authors concluded that outcome deteriorated when disc replacement was performed bisegmentally, with an increase of complications for bisegmental replacements in comparison with monosegmental disc arthroplasty. The goal of the present retrospective study is to investigate results in a group of patients who have received bisegmental TDR with SB Charitè III artificial disc for degenerative disc disease with a minimum follow-up of 3 years, and to compare the results of 2-level disc replacement versus 1-level patients treated with the same prosthesis. A total of 32 patients had at least 3-years follow-up and were reviewed. The average age of the patients was 38.5 years. There were 11 males and 21 females. About 16 patients received 2-level TDR (SB Charitè III) and 16 received 1-level TDR (SB Charitè III). Both radiographic and functional outcome analysis, including patient’s satisfaction, was performed. There were no signs of degenerative changes of the adjacent segments in any case of the 2- or 1-level TDR. There was no statistically significant difference between 2- and 1-level TDR both at 12 months and at 3-years follow-up on functional outcome scores. There was a statistically insignificant difference concerning the patients satisfaction between 1- and 2-level surgeries at the last follow-up (P = 0.46). In the 2-level TDR patients, there were 5 minor complications (31.25%), whereas major complications occurred in 4 more patients (25%) and required a new surgery in 2 cases (12.5%). In the 1-level cases there were 2 minor complications (12.5%) and 2 major complications (12.5%) and a new revision surgery was required in 1 patient (6.25%). In conclusion, the use of 2-level disc replacement at last follow-up presented a higher incidence of complications than in cases

  8. Prosthetic lumbar disc replacement for degenerative disc disease.

    PubMed

    Kulkarni, Arvind G; Diwan, Ashish D

    2005-12-01

    Mechanical articulated device to replace intervertebral disc as a treatment for low back pain secondary to disc degeneration has emerged as a promising tool for selected patients. The potential advantages are prevention of adjacent segment degeneration, maintenance of mobility as well as avoidance of all the complications associated with fusion. The short-term results have been comparable to that of fusion, a few mid-term results have shown mixed outcome, but information on long-term results and performance are not available at present. The rationale for lumbar disc arthroplasty, indications, contraindications, the various artificial devices in the market and the concepts intrinsic to each of them, basic technique of insertion, complications are discussed and a brief summary of our experience with one of the devices is presented. PMID:16565543

  9. Total Disc Replacement in Lumbar Degenerative Disc Diseases

    PubMed Central

    2015-01-01

    More than 10 years have passed since lumbar total disc replacement (LTDR) was introduced for the first time to the world market for the surgical management of lumbar degenerative disc disease (DDD). It seems like the right time to sum up the relevant results in order to understand where LTDR stands on now, and is heading forward to. The pathogenesis of DDD has been currently settled, but diagnosis and managements are still controversial. Fusion is recognized as golden standard of surgical managements but has various kinds of shortcomings. Lately, LTDR has been expected to replace fusion surgery. A great deal of LTDR reports has come out. Among them, more than 5-year follow-up prospective randomized controlled studies including USA IDE trials were expected to elucidate whether for LTDR to have therapeutic benefit compared to fusion. The results of these studies revealed that LTDR was not inferior to fusion. Most of clinical studies dealing with LTDR revealed that there was no strong evidence for preventive effect of LTDR against symptomatic degenerative changes of adjacent segment disease. LTDR does not have shortcomings associated with fusion. However, it has a potentiality of the new complications to occur, which surgeons have never experienced in fusion surgeries. Consequently, longer follow-up should be necessary as yet to confirm the maintenance of improved surgical outcome and to observe any very late complications. LTDR still may get a chance to establish itself as a substitute of fusion both nominally and virtually if it eases the concerns listed above. PMID:26713139

  10. Material Science in Cervical Total Disc Replacement

    PubMed Central

    Pham, Martin H.; Mehta, Vivek A.; Tuchman, Alexander; Hsieh, Patrick C.

    2015-01-01

    Current cervical total disc replacement (TDR) designs incorporate a variety of different biomaterials including polyethylene, stainless steel, titanium (Ti), and cobalt-chrome (CoCr). These materials are most important in their utilization as bearing surfaces which allow for articular motion at the disc space. Long-term biological effects of implanted materials include wear debris, host inflammatory immune reactions, and osteolysis resulting in implant failure. We review here the most common materials used in cervical TDR prosthetic devices, examine their bearing surfaces, describe the construction of the seven current cervical TDR devices that are approved for use in the United States, and discuss known adverse biological effects associated with long-term implantation of these materials. It is important to appreciate and understand the variety of biomaterials available in the design and construction of these prosthetics and the considerations which guide their implementation. PMID:26523281

  11. Material Science in Cervical Total Disc Replacement.

    PubMed

    Pham, Martin H; Mehta, Vivek A; Tuchman, Alexander; Hsieh, Patrick C

    2015-01-01

    Current cervical total disc replacement (TDR) designs incorporate a variety of different biomaterials including polyethylene, stainless steel, titanium (Ti), and cobalt-chrome (CoCr). These materials are most important in their utilization as bearing surfaces which allow for articular motion at the disc space. Long-term biological effects of implanted materials include wear debris, host inflammatory immune reactions, and osteolysis resulting in implant failure. We review here the most common materials used in cervical TDR prosthetic devices, examine their bearing surfaces, describe the construction of the seven current cervical TDR devices that are approved for use in the United States, and discuss known adverse biological effects associated with long-term implantation of these materials. It is important to appreciate and understand the variety of biomaterials available in the design and construction of these prosthetics and the considerations which guide their implementation. PMID:26523281

  12. Heterotopic ossification following lumbar total disc replacement.

    PubMed

    Park, Se-Jun; Kang, Kyung-Jung; Shin, Seong-Kee; Chung, Sung-Soo; Lee, Chong-Suh

    2011-08-01

    The main goal of total disc replacement (TDR) is to preserve motion. Despite reports of good clinical outcomes, various degrees of heterotopic ossification after TDR have been reported. The purpose of this study was to investigate the prevalence and its clinical relevance of heterotopic ossification. We evaluated 65 consecutive patients (82 segments) with mean follow-up duration of 45 months (range, 12-88 months). Two kinds of prosthesis, ProDisc® for 75 segments (91.5%) and CHARITE™ for seven segments (8.5%), were used. Patients with heterotopic ossification were compared with those without heterotopic ossification with regard to segmental flexion-extension ROM, VAS and ODI. We analysed the occurrence site by nine zones. Heterotopic ossification was detected in 25 out of 82 segments (30.5%) at a mean follow-up of 17 months. According to McAfee's classification, there was Class-I heterotopic ossification in eight segments (9.8%), Class-II in 12 segments (14.6%), and Class-III in five segments (6.1%). There was no Class-IV heterotopic ossification. There were no significant differences in the segmental ROM, VAS and ODI between the patients with Class-I or Class-II heterotopic ossification and those without heterotopic ossification The segmental ROM in the patients with Class-III heterotopic ossification was significantly decreased compared with the patients without heterotopic ossification (p = 0.018). But VAS and ODI were not significantly different compared with those of patients with no heterotopic ossification. Most heterotopic ossification (82.5%) was detected in the anterior and posterior aspects. In conclusion, most of the heterotopic ossification (Classes I and II) did not affect segmental ROM and clinical outcomes such as pain or function. In Class-III heterotopic ossification segmental ROM was decreased, but it did not affect clinical outcomes. PMID:20652248

  13. Adjacent segment disc pressures following two-level cervical disc replacement versus simulated anterior cervical fusion.

    PubMed

    Laxer, Eric B; Darden, Bruce V; Murrey, Daniel B; Milam, R Alden; Rhyne, Alfred L; Claytor, Brian; Nussman, Donna S; Powers, Timothy W; Davies, Matthew A; Bryant, S Chad; Larsen, Scott P; Bhatt, Meghal; Brodziak, John; Polic, Jelena

    2006-01-01

    Anterior cervical fusion (ACF) has been shown to alter the biomechanics of adjacent segments of the cervical spine. The goal of total disc replacement is to address pathology at a given disc with minimal disruption of the operated or adjacent segments. This study compares the pressure within discs adjacent to either a two-level simulated ACDF or a two-level total disc replacement with the ProDisc-C. A special automated motion testing apparatus was constructed. Four fresh cadaveric cervical spine specimens were affixed to the test stand and tested in flexion and extension under specific loads. Intradiscal, miniature strain-gauge-based transducers were placed in the discs above and below the "treated" levels. The specimens were then tested in flexion and extension. Pressure and overall angular displacement were measured. In the most extreme and highest quality specimen the difference at C3/C4 registered 800 kPa and the difference at C6/C7 registered 50 kPa. This same quality specimen treated with the ProDisc reached a flexion angle at much lower moments, 24.3 degrees at 5 N-m, when compared to the the SACF 12.2 degrees at 8.6 N-m. Therefore, the moment needed to achieve 15 degrees of flexion with the SACF treatment was 5.5 N-m and the ProDisc treatment was only 2.9 N-m. This initial data would indicate that adjacent level discs experience substantially lower pressure after two-level disc replacement when compared to two-level SACF. Additional testing to further support these observations is ongoing. PMID:17108473

  14. Novel indication for posterior dynamic stabilization: Correction of disc tilt after lumbar total disc replacement

    PubMed Central

    Cheng, Wayne K.; Palmer, Daniel Kyle; Jadhav, Vikram

    2011-01-01

    Background The increase in total disc replacement procedures performed over the last 5 years has increased the occurrence of patients presenting with postoperative iatrogenic deformity requiring revision surgery. Proposed salvage treatments include device retrieval followed by anterior lumbar interbody fusion or posterior fusion. We propose a novel approach for the correction of disc tilt after total disc replacement using a posterior dynamic stabilization system. Methods Pedicle screws can be inserted either in an open manner or percutaneously by standard techniques under fluoroscopy. The collapsed side is expanded, and the convex side is compressed. Universal spacers are placed bilaterally, with the spacer on the collapsed side being taller by 6 mm. Cords are threaded through the spacers and pulled into place with the tensioning instrument. Extra tension is applied to the convex side, and the wound is closed by standard techniques. Results Three patients presenting with tilted total disc replacement devices underwent corrective surgery with posterior dynamic stabilization. Radiographs confirmed correction of deformity in all cases. Conclusions/Level of Evidence This technical note presents a novel indication for posterior dynamic stabilization and describes its surgical application to the correction of disc tilt after total disc replacement. This is level V evidence. PMID:25802667

  15. Pitfalls

    NASA Technical Reports Server (NTRS)

    Triffet, Terry

    1990-01-01

    Though potentially of great benefit to the nation, the experience of the workshop participants and their discussions with Sea Grant and Land Grant officials make it clear that the Space Grant Program must avoid certain pitfalls of the past and present if it is to be successful. The most important of these are listed and briefly discussed.

  16. Preclinical and clinical experience with a viscoelastic total disc replacement

    PubMed Central

    Rischke, Burkhard; Ross, Raymond S.; Jollenbeck, Boris A.; Zimmers, Kari B.; Defibaugh, Neal D.

    2011-01-01

    Background The purpose of this study is to describe the mechanical durability and the clinical and radiographic outcomes of a viscoelastic total disc replacement (VTDR). The human intervertebral disc is a complex, viscoelastic structure, permitting and constraining motion in 3 axes, thus providing stability. The ideal disc replacement should be viscoelastic and deformable in all directions, and it should restore disc height and angle. Methods Mechanical testing was conducted to validate the durability of the VTDR, and a clinical study was conducted to evaluate safety and performance. Fifty patients with single-level, symptomatic lumbar degenerative disc disease at L4-5 or L5-S1 were enrolled in a clinical trial at 3 European sites. Patients were assessed clinically and radiographically for 2 years by the Oswestry Disability Index (ODI), a visual analog scale (VAS), and independent radiographic analyses. Results The VTDR showed a fatigue life in excess of 50 million cycles (50-year equivalent) and a physiologically appropriate level of stiffness, motion, geometry, and viscoelasticity. We enrolled 28 men and 22 women in the clinical study, with a mean age of 40 years. Independent quantitative radiographic assessment indicated that the VTDR restored and maintained disc height and lordosis while providing physiologic motion. Mean ODI scores decreased from 48% preoperatively to 23% at 2 years’ follow-up. Mean VAS low-back pain scores decreased from 7.1 cm to 2.9 cm. Median scores indicated that half of the patient population had ODI scores below 10% and VAS low-back pain scores below 0.95 cm at 2 years. Conclusions The VTDR has excellent durability and performs clinically and radiographically as intended for the treatment of symptomatic lumbar degenerative disc disease. Clinical Relevance The VTDR is intended to restore healthy anatomic properties and stability characteristics to the spinal segment. This study is the first to evaluate a VTDR in a 50-patient

  17. Disc calibration for digital templating in hip replacement.

    PubMed

    Kulkarni, A; Partington, P; Kelly, D; Muller, S

    2008-12-01

    Digital radiography is becoming widespread. Accurate pre-operative templating of digital images of the hip traditionally involves positioning a calibration object at its centre. This can be difficult and cause embarrassment. We have devised a method whereby a planar disc placed on the radiographic cassette accounts for the expected magnification. Initial examination of 50 pelvic CT scans showed a mean hip centre distance of 117 mm (79 to 142) above the gluteal skin. Further calculations predicted that a disc of 37.17 mm diameter, placed on the cassette, would appear identical to a 30 mm sphere placed at the level of the centre of the hip as requested by our templating software. We assessed accuracy and reproducibility by 'reverse calibration' of 20 radiographs taken three months after hip replacement using simultaneous sphere and disc methods, and a further 20 with a precision disc of accurate size. Even when variations in patient size were ignored, the disc proved more accurate and reliable than the sphere. The technique is reliable, robust, cost effective and acceptable to patients and radiographers. It can easily be used in any radiography department after a few simple calculations and manufacture of appropriately-sized discs. PMID:19043135

  18. Lumbar disc replacement: preliminary results with ProDisc II after a minimum follow-up period of 1 year.

    PubMed

    Tropiano, Patrick; Huang, Russel C; Girardi, Federico P; Marnay, Thierry

    2003-08-01

    Total disc replacement has the potential to replace fusion as the gold standard surgical treatment of degenerative disc disease. Potential advantages of disc replacement over fusion include avoidance of pseudarthrosis, postoperative orthoses, and junctional degeneration. After observing satisfactory clinical results at 7-11 years' follow-up with the ProDisc first-generation implant, a second-generation prosthesis was designed. This study is a prospective analysis of the early results of total disc replacement with the ProDisc II total disc prosthesis. Fifty-three patients had single-level or multilevel disc replacement and were evaluated clinically and radiographically preoperatively and at mean 1.4-year follow-up. There were clinically and statistically significant improvements in back and leg pain Visual Analog Scale and Oswestry disability scores that were maintained at final follow-up. The clinical results of patients with single- and multilevel surgery were equivalent. Satisfactory results were achieved in 90% of patients who had previous lumbar surgery. Complications occurred in 9% of patients and included vertebral body fracture, transient radicular pain, implant malposition, and transient retrograde ejaculation. Three patients (6%) required reoperation to address complications. No mechanical failure of the implants or loosening was observed, and the prostheses retained motion. Randomized, prospective, long-term studies will be necessary to compare the effectiveness of arthrodesis with total disc replacement. PMID:12902952

  19. Total disc replacement surgery for symptomatic degenerative lumbar disc disease: a systematic review of the literature.

    PubMed

    van den Eerenbeemt, Karin D; Ostelo, Raymond W; van Royen, Barend J; Peul, Wilco C; van Tulder, Maurits W

    2010-08-01

    The objective of this study is to evaluate the effectiveness and safety of total disc replacement surgery compared with spinal fusion in patients with symptomatic lumbar disc degeneration. Low back pain (LBP), a major health problem in Western countries, can be caused by a variety of pathologies, one of which is degenerative disc disease (DDD). When conservative treatment fails, surgery might be considered. For a long time, lumbar fusion has been the "gold standard" of surgical treatment for DDD. Total disc replacement (TDR) has increased in popularity as an alternative for lumbar fusion. A comprehensive systematic literature search was performed up to October 2008. Two reviewers independently checked all retrieved titles and abstracts, and relevant full text articles for inclusion. Two reviewers independently assessed the risk of bias of included studies and extracted relevant data and outcomes. Three randomized controlled trials and 16 prospective cohort studies were identified. In all three trials, the total disc replacement was compared with lumbar fusion techniques. The Charité trial (designed as a non-inferiority trail) was considered to have a low risk of bias for the 2-year follow up, but a high risk of bias for the 5-year follow up. The Charité artificial disc was non-inferior to the BAK Interbody Fusion System on a composite outcome of "clinical success" (57.1 vs. 46.5%, for the 2-year follow up; 57.8 vs. 51.2% for the 5-year follow up). There were no statistically significant differences in mean pain and physical function scores. The Prodisc artificial disc (also designed as a non-inferiority trail) was found to be statistically significant more effective when compared with the lumbar circumferential fusion on the composite outcome of "clinical success" (53.4 vs. 40.8%), but the risk of bias of this study was high. Moreover, there were no statistically significant differences in mean pain and physical function scores. The Flexicore trial, with a high

  20. Total disc replacement surgery for symptomatic degenerative lumbar disc disease: a systematic review of the literature

    PubMed Central

    van den Eerenbeemt, Karin D.; van Royen, Barend J.; Peul, Wilco C.; van Tulder, Maurits W.

    2010-01-01

    The objective of this study is to evaluate the effectiveness and safety of total disc replacement surgery compared with spinal fusion in patients with symptomatic lumbar disc degeneration. Low back pain (LBP), a major health problem in Western countries, can be caused by a variety of pathologies, one of which is degenerative disc disease (DDD). When conservative treatment fails, surgery might be considered. For a long time, lumbar fusion has been the “gold standard” of surgical treatment for DDD. Total disc replacement (TDR) has increased in popularity as an alternative for lumbar fusion. A comprehensive systematic literature search was performed up to October 2008. Two reviewers independently checked all retrieved titles and abstracts, and relevant full text articles for inclusion. Two reviewers independently assessed the risk of bias of included studies and extracted relevant data and outcomes. Three randomized controlled trials and 16 prospective cohort studies were identified. In all three trials, the total disc replacement was compared with lumbar fusion techniques. The Charité trial (designed as a non-inferiority trail) was considered to have a low risk of bias for the 2-year follow up, but a high risk of bias for the 5-year follow up. The Charité artificial disc was non-inferior to the BAK® Interbody Fusion System on a composite outcome of “clinical success” (57.1 vs. 46.5%, for the 2-year follow up; 57.8 vs. 51.2% for the 5-year follow up). There were no statistically significant differences in mean pain and physical function scores. The Prodisc artificial disc (also designed as a non-inferiority trail) was found to be statistically significant more effective when compared with the lumbar circumferential fusion on the composite outcome of “clinical success” (53.4 vs. 40.8%), but the risk of bias of this study was high. Moreover, there were no statistically significant differences in mean pain and physical function scores. The Flexicore trial

  1. Painless squeaking following cervical disc replacement: A case report

    PubMed Central

    Siddiqui, Athar; Hulme, Christopher

    2015-01-01

    Background We present a case of painless squeaking following cervical disc replacement which to our knowledge has not previously been reported in the literature. Methods A 45 year old gentleman presented with severe right sided C6 radiculopathy. He complained of more than 6 weeks of severe dysaesthesia in the right arm with pain radiating into the hand, thumb, index, middle and ring fingers. MRI confirmed severe impingement of C6 and C7 nerve roots. After trying a period of conservative treatment he underwent anterior cervical decompression with total cervical disc replacement of C5-6 and C6-7. Results Being a keen athlete he started running at 6 months post operatively. At his 12 month outpatient he presented us with an audio file containing squeaking from his neck. This was recorded immediately following a 9.5 mile hard surface run. The squeak got progressively less in intensity over 12 hours and disappeared after 24 hours. All instances of squeaking occurred after exercise where impact (running) or vibration (cycling) took place. This was first noticed 6 months post operatively when he restarted exercising. All episodes were completely painless. At his 18 month outpatient review the squeaking had reduced in frequency and intensity. At his 24 month review it had abated completely. Conclusion The aetiology of this painless squeaking has been elusive and is likely to be multifactorial. However we hypothesise that the audible squeak associated with the prestige LP disc maybe related to specific design characteristics and needs further evaluation. PMID:26484007

  2. Translation of an Engineered Nanofibrous Disc-like Angle Ply Structure for Intervertebral Disc Replacement in a Small Animal Model

    PubMed Central

    Martin, John T.; Milby, Andrew H.; Chiaro, Joseph A.; Kim, Dong Hwa; Hebela, Nader M.; Smith, Lachlan J.; Elliott, Dawn M.; Mauck, Robert L.

    2015-01-01

    Intervertebral disc degeneration has been implicated in the etiology of low back pain; however the current surgical strategies for treating symptomatic disc disease are limited. A variety of materials have been developed to replace disc components, including the nucleus pulposus (NP), the annulus fibrosus (AF), and their combination into disc-like engineered constructs. We have previously shown that layers of electrospun poly(ε-caprolactone) scaffold, mimicking the hierarchical organization of the native AF, have functional parity with native tissue. Likewise, we have combined these structures with cell-seeded hydrogels (as an NP replacement) to form disc-like angle ply structures (DAPS). The objective of this study was to develop a model for the evaluation of DAPS in vivo. Through a series of studies, we developed a surgical approach to replace the rat caudal disc with an acellular DAPS and then stabilize the motion segment by external fixation. We then optimized cell infiltration into DAPS by including sacrificial poly(ethylene oxide) layers interspersed throughout the angle-ply structure. Our findings illustrate that DAPS are stable in the caudal spine, are infiltrated by cells from the peri-implant space, and that infiltration is expedited by providing additional routes for cell migration. These findings establish a new in vivo platform in which to evaluate and optimize the design of functional disc replacements. PMID:24560621

  3. Lumbar disc replacement in adolescents: An initial experience in two cases

    PubMed Central

    Kasliwal, Manish K.; Deutsch, Harel

    2012-01-01

    Management of painful lumbar disc degeneration is one of the most common conditions treated by spine surgeons. Several recent prospective multicenter trials have demonstrated the effectiveness of artificial lumbar disc replacement in treating discogenic lower back pain. Though data on the safety and effectiveness has gradually been accumulated in adults, there is a lack of published data on the effectiveness and feasibility of lumbar artificial disc replacement in adolescents. The authors share their initial clinical experience with lumbar disc replacement in a couple of adolescents. PMID:23248694

  4. Wnt signaling during tooth replacement in zebrafish (Danio rerio): pitfalls and perspectives.

    PubMed

    Huysseune, Ann; Soenens, Mieke; Elderweirdt, Fien

    2014-01-01

    The canonical (β-catenin dependent) Wnt signaling pathway has emerged as a likely candidate for regulating tooth replacement in continuously renewing dentitions. So far, the involvement of canonical Wnt signaling has been experimentally demonstrated predominantly in amniotes. These studies tend to show stimulation of tooth formation by activation of the Wnt pathway, and inhibition of tooth formation when blocking the pathway. Here, we report a strong and dynamic expression of the soluble Wnt inhibitor dickkopf1 (dkk1) in developing zebrafish (Danio rerio) tooth germs, suggesting an active repression of Wnt signaling during morphogenesis and cytodifferentiation of a tooth, and derepression of Wnt signaling during start of replacement tooth formation. To further analyse the role of Wnt signaling, we used different gain-of-function approaches. These yielded disjunct results, yet none of them indicating enhanced tooth replacement. Thus, masterblind (mbl) mutants, defective in axin1, mimic overexpression of Wnt, but display a normally patterned dentition in which teeth are replaced at the appropriate times and positions. Activating the pathway with LiCl had variable outcomes, either resulting in the absence, or the delayed formation, of first-generation teeth, or yielding a regular dentition with normal replacement, but no supernumerary teeth or accelerated tooth replacement. The failure so far to influence tooth replacement in the zebrafish by perturbing Wnt signaling is discussed in the light of (i) potential technical pitfalls related to dose- or time-dependency, (ii) the complexity of the canonical Wnt pathway, and (iii) species-specific differences in the nature and activity of pathway components. Finally, we emphasize the importance of in-depth knowledge of the wild-type pattern for reliable interpretations. It is hoped that our analysis can be inspiring to critically assess and elucidate the role of Wnt signaling in tooth development in polyphyodonts. PMID

  5. Wnt signaling during tooth replacement in zebrafish (Danio rerio): pitfalls and perspectives

    PubMed Central

    Huysseune, Ann; Soenens, Mieke; Elderweirdt, Fien

    2014-01-01

    The canonical (β-catenin dependent) Wnt signaling pathway has emerged as a likely candidate for regulating tooth replacement in continuously renewing dentitions. So far, the involvement of canonical Wnt signaling has been experimentally demonstrated predominantly in amniotes. These studies tend to show stimulation of tooth formation by activation of the Wnt pathway, and inhibition of tooth formation when blocking the pathway. Here, we report a strong and dynamic expression of the soluble Wnt inhibitor dickkopf1 (dkk1) in developing zebrafish (Danio rerio) tooth germs, suggesting an active repression of Wnt signaling during morphogenesis and cytodifferentiation of a tooth, and derepression of Wnt signaling during start of replacement tooth formation. To further analyse the role of Wnt signaling, we used different gain-of-function approaches. These yielded disjunct results, yet none of them indicating enhanced tooth replacement. Thus, masterblind (mbl) mutants, defective in axin1, mimic overexpression of Wnt, but display a normally patterned dentition in which teeth are replaced at the appropriate times and positions. Activating the pathway with LiCl had variable outcomes, either resulting in the absence, or the delayed formation, of first-generation teeth, or yielding a regular dentition with normal replacement, but no supernumerary teeth or accelerated tooth replacement. The failure so far to influence tooth replacement in the zebrafish by perturbing Wnt signaling is discussed in the light of (i) potential technical pitfalls related to dose- or time-dependency, (ii) the complexity of the canonical Wnt pathway, and (iii) species-specific differences in the nature and activity of pathway components. Finally, we emphasize the importance of in-depth knowledge of the wild-type pattern for reliable interpretations. It is hoped that our analysis can be inspiring to critically assess and elucidate the role of Wnt signaling in tooth development in polyphyodonts. PMID

  6. Vertical split fracture of the vertebral body following total disc replacement using ProDisc: report of two cases.

    PubMed

    Shim, Chan Shik; Lee, Seungcheol; Maeng, Dae Hyun; Lee, Sang-Ho

    2005-10-01

    As ProDisc has a tall keel on the plates, it has the potential to cause a vertical fracture of the vertebral body. However, to our knowledge, there is no previously reported case of a vertical split fracture of the vertebral body after ProDisc disc arthroplasty that was attributed to the keel design of the ProDisc. We report two cases of vertical split fracture of the vertebral body after total disc replacement (TDR) with ProDisc and discuss the issue of the height of the keel of the prosthesis. Even though there was no serious clinical consequence as a result of the fracture in our cases, except the fact that the patients were dissatisfied with the surgery at 3-month follow-up because of the prolonged back pain, the potential of the fracture to cause other serious complications such as hematoma, device migration, or surgical failure cannot be ignored. The keel design of the ProDisc has the disadvantage that it can cause a vertebral body fracture in some patients. Therefore, care should be exercised not to fracture the vertebral body when TDR is done with the ProDisc, especially in a patient with small vertebral body height or when it is done at multiple levels. PMID:16189463

  7. Disc replacement using Pro-Disc C versus fusion: a prospective randomised and controlled radiographic and clinical study

    PubMed Central

    Ahlhelm, F.; Pitzen, T.; Steudel, W. I.; Jung, J.; Shariat, K.; Steimer, O.; Bachelier, F.; Pape, D.

    2006-01-01

    Anterior cervical discectomy and fusion (ACDF) may be considered to be the gold standard for treatment of symptomatic degenerative disc disease within the cervical spine. However, fusion of the segment may result in progressive degeneration of the adjacent segments. Therefore, dynamic stabilization procedures have been introduced. Among these, artificial disc replacement by disc prosthesis seems to be promising. However, to be so, segmental motion must be preserved. This, again, is very difficult to judge and has not yet been proven. The aim of the current study was to first analyse the segmental motion following artificial disc replacement using a disc prosthesis. A second aim was to compare both segmental motion as well as clinical result to the current gold standard (ACDF). This is a prospective controlled study. Twenty-five patients with cervical disc herniation were enrolled and assigned to either study group (receiving a disc prosthesis) or control group (receiving ACDF, using a cage with bone graft and an anterior plate.) Radiostereometric analysis was used to quantify intervertebral motion immediately as well as 3, 6, 12 and 24 weeks postoperatively. Further, clinical results were judged using visual analogue scale and neuro-examination. Cervical spine segmental motion decreased over time in the presence of disc prosthesis or ACDF. However, the loss of segmental motion is significantly higher in the ACDF group, when looked at 3, 6, 12 and 24 weeks after surgery. We observed significant pain reduction in neck and arm postoperatively, without significant difference between both groups (P > 0.05). Cervical spine disc prosthesis preserves cervical spine segmental motion within the first 6 months after surgery. The clinical results are the same when compared to the early results following ACDF. PMID:17106665

  8. Early failure of lumbar disc replacement: case report and review of the literature.

    PubMed

    Stieber, Jonathan R; Donald, Gordon D

    2006-02-01

    We report a case of a patient who underwent two-level lumbar total disc replacement at L4-L5 and L5-S1 with the ProDisc II prosthesis, who was diagnosed with early anterior migration of the caudally placed device with partial occlusion of the left common iliac vein. The device was explanted and revised to an anterior lumbar interbody fusion with posterior instrumented fusion. Despite the substantial experience with lumbar disc arthroplasty in Europe and the United States, there exist few reports of device explantation or revision. To our knowledge, early postoperative vascular complications, while discussed hypothetically, have not been reported. With implantation of the total disc replacement in proximity to the great vessels, the potential for vascular complications is clearly substantial. The technical aspects of the device explantation are discussed as well as issues pertinent to early failure. A literature review of device complications associated with lumbar total disc replacement is also presented. PMID:16462220

  9. Early clinical and radiographical results of keel-less and shallow keel cervical disc replacement

    PubMed Central

    Ling, Ji Min; Tiruchelvarayan, Rajendra

    2015-01-01

    Background: Cervical disc replacements has been shown to be as effective as fusions in the treatment of radiculopathy or myelopathy due to disc prolapse. Newer implants were designed to reduce the difficulty of end-plate preparation. Since 2010, the authors have started using Discocerv (Alphatec Spine, Carlsbad, USA) a keel-less implant and Activ-C (B. Braun, Sheffield, UK), a shallow keel implant. Aim: The aim of this study was to compare the duration of surgery between cervical disc replacement and anterior cervical discectomy and fusion, and also to evaluate the functional outcome, complications, and radiographic outcome of cervical disc replacement. Results: Fifty patients were included (20 disc replacement and 30 fusion). This was a single surgeon retrospective study, with all surgery performed by the senior author (RT). The mean operation duration for single-level disc replacement was 2.6 h, and for single-level fusion was 2.4 h (P = 0.4684). For 2-levels surgery, the result was 3.5 h for 2-level hybrid surgery (one level disc replacement and one level fusion) and 3.4 h for fusion (P = 0.4489). Disc replacement resulted in preservation of an average of 67% of the angle of motion at the sagittal plane (FFflexion-extension). The average range of motion after disc replacement was 6.1°. The median clinical follow-up duration was 2 years (average 1.8 years). There was no incidence of major complications or significant neurovascular injury in this series of patients. A significant improvement in short form-36 scores was seen as early as 3 months postoperative (from 58 preoperative to 92 at 3 months). The improvement was sustained up to the fourth year of follow-up. Conclusion: Cervical arthroplasty with keel-less and shallow keel implants are safe and relatively easy to perform. The surgical time for disc replacement is not significantly longer than standard fusion surgery. There is reasonably good preservation of motion. The short-term functional improvement is

  10. Physical capability outcomes after total disc replacement with ProDisc-L

    PubMed Central

    Sullivan, Humbert G.; Bobenmoyer, Robert L.; Boland, Kevin M.; Cerniglia, Molly M.; McHugh, Vicki L.; Born, Hayley L.; Mathiason, Michelle A.; Ladwig, Nicholas R.

    2012-01-01

    Background Lumbar disc arthroplasty (total disc replacement [TDR]) outcomes have been evaluated using subjective, patient-reported measures of pain, health, and functional impairment. As a condition of TDR coverage, our institution's health plan required that objective physical performance data be collected. Thus our study was designed to explore (1) the feasibility of using preoperative and 1-year postoperative performance on functional capacity tasks as an outcome metric for TDR with ProDisc-L (PD-L) (Synthes Spine, West Chester, Pennsylvania), (2) the magnitude and significance of changes in preoperative and postoperative performance, and (3) whether changes noted in performance are reflected in the subjective measures. Methods Seven adapted WorkWell tasks (physical capability assessment tool [PCAT]) (WorkWell Systems, Duluth, Minnesota) were performed preoperatively and 1 year postoperatively by 18 patients who received either single-level or 2-level PD-L implants. Demographic and medical data were reviewed. Results The PCAT was implemented easily, and the tasks took approximately 30 minutes to complete. Percent improvement and preoperative and postoperative physical capability outcomes for each PCAT task are as follows: squat, 79% (10.7 ± 7.1 repetitions vs 19.2 ± 2.0 repetitions, P < .001); forward bend, 121% (110.2 ± 68.8 seconds vs 243.6 ± 77.2 seconds, P < .001); kneel, 92% (283.2 ± 173.2 seconds vs 544.7 ± 109.3 seconds, P < .001); floor-to-waist lift, 128% (16.1 ± 9.9 lb vs 36.7 ± 20.3 lb, P < .001); horizontal carry, 119% (19.7 ± 8.6 lb vs 43.2 ± 18.3 lb, P < .001); push, 32% (67.7 ± 19.2 lb vs 89.4 ± 24.4 lb, P < .001); and pull, 40% (57.6 ± 17.1 lb vs 80.9 ± 26.4 lb, P < .001). Visual analog scale scores for pain (5.1 ± 1.7 vs 1.4 ± 1.6, P < .001), Oswestry Disability Index scores (49.0% ± 13.2% vs 15.2% ± 14.3%, P < .001), and amount of narcotic use (26.1 ± 43.8 mg of morphine equivalent vs 1.9 ± 7.3 mg of morphine equivalent, P

  11. Lumbar disk replacement with the ProDisc prosthesis.

    PubMed

    Mirovsky, Yigal; Shalmon, Ehud; Halpern, Zvi; Halperin, Nahum; Blankstein, Alexander; Peer, Amir

    2008-02-01

    Twenty-two ProDisc II prostheses (Spine Solutions, New York, New York) were implanted in 21 patients with degenerative disk disease at L5-S1 (19 disks) and L4-L5 (3 disks). After mean follow-up of 3.1 years (range, 17-49 months), pain intensity in all but 3 patients had improved from an average of 7.7 preoperatively to 4.6 postoperatively (P< .001) on a visual analog scale. Average Oswestry Disability Index score improved from 61 to 35 (P< .001). Radiographic reconstruction of the disk space height was achieved in all cases. Previous diskectomy at the implanted level and disk degeneration adjacent to previous fusion negatively influenced the results. PMID:19292209

  12. Lumbar total disc replacement using ProDisc II: a prospective study with a 2-year minimum follow-up.

    PubMed

    Chung, Sung Soo; Lee, Chong Suh; Kang, Chang Seok

    2006-08-01

    A lumbar total disc replacement (TDR) is believed to be a promising substitute in the surgical treatment for lumbar degenerative disc disease. The purpose of this study is to report the clinical and radiographic outcomes of 36 consecutive patients who underwent lumbar TDR using ProDisc II, and the factors associated with a better clinical outcome after a 2-year minimum follow-up. At the time of the latest follow-up, the success rate was 94% of 36 patients according to the criteria of the US Food and Drug Administration. Of the 10 patients unable to work preoperatively, 7 patients returned to work. Moreover, mean score on the visual analog scale for low back and leg pain improved significantly from 7.5 and 4.7 to 3.0 and 1.2, respectively (P<0.001). In addition, mean Oswestry disability index scores improved significantly from 69.2 to 21.0 (P<0.001). Mean disc height at the operative level increased significantly from 9.0 to 17.6 mm, and mean range of motion increased significantly from 9.7 to 12.7 degrees (P<0.01). Statistical analysis showed that the factors associated with a better clinical outcome were single level, and a higher postoperative segmental ROM at the operative level. At a minimum follow-up of 2 years, the lumbar TDR using ProDisc II showed excellent clinical and radiographic outcomes without any significant complication. However, future efforts need to be directed toward the evaluation of a larger number of patients with longer follow-up. PMID:16891976

  13. Comparison of in vivo and simulator-retrieved metal-on-metal cervical disc replacements

    PubMed Central

    Kurtz, Steven M.; Ciccarelli, Lauren; Harper, Megan L.; Siskey, Ryan; Shorez, Jacob; Chan, Frank W.

    2012-01-01

    Background Cervical disc arthroplasty is regarded as a promising treatment for myelopathy and radiculopathy as an alternative to cervical spine fusion. On the basis of 2-year clinical data for the PRESTIGE® Cervical Disc (Medtronic, Memphis, Tennessee), the Food and Drug Administration recommended conditional approval in September 2006 and final approval in July 2007; however, relatively little is known about its wear and damage modes in vivo. The main objective was to analyze the tribological findings of the PRESTIGE® Cervical Disc. This study characterized the in vivo wear patterns of retrieved cervical discs and tested the hypothesis that the total disc replacements exhibited similar surface morphology and wear patterns in vitro as in vivo. Methods Ten explanted total disc replacements (PRESTIGE®, PRESTIGE® I, and PRESTIGE® II) from 10 patients retrieved after a mean of 1.8 years (range, 0.3–4.1 years) were analyzed. Wear testing included coupled lateral bending ( ±4.7°) and axial rotation ( ±3.8°) with a 49 N axial load for 5 million cycles followed by 10 million cycles of flexion-extension ( ±9.7°) with 148 N. Implant surfaces were characterized by the use of white-light interferometry, scanning electron microscopy, and energy dispersive spectroscopy. Results The explants generally exhibited a slightly discolored, elliptic wear region of varying dimension centered in the bearing center, with the long axis oriented in the medial-lateral direction. Abrasive wear was the dominant in vivo wear mechanism, with microscopic scratches generally oriented in the medial-lateral direction. Wear testing resulted in severe abrasive wear in a curvilinear fashion oriented primarily in the medial-lateral direction. All retrievals showed evidence of an abrasive wear mechanism. Conclusions This study documented important similarity between the wear mechanisms of components tested in vitro and explanted PRESTIGE® Cervical Discs; however, the severity of wear was

  14. Cervical artificial disc replacement with ProDisc-C: clinical and radiographic outcomes with long-term follow-up.

    PubMed

    Malham, Gregory M; Parker, Rhiannon M; Ellis, Ngaire J; Chan, Philip G; Varma, Dinesh

    2014-06-01

    Cervical artificial disc replacement (ADR) is indicated for the treatment of severe radiculopathy permitting neural decompression and maintenance of motion. We evaluated the clinical and radiographic outcomes in cervical ADR patients using the ProDisc-C device (DePuy Synthes, West Chester, PA, USA) with a 5-9 year follow-up. Data were collected through a prospective registry, with retrospective analysis performed on 24 consecutive patients treated with cervical ADR by a single surgeon. All patients underwent single- or two-level ADR with the ProDisc-C device. Outcome measures included neck and arm pain (visual analogue scale), disability (neck disability index [NDI]), complications and secondary surgery rates. Flexion-extension cervical radiographs were performed to assess range of motion (ROM) of the device and adjacent segment disease (ASD). Average follow-up was 7.7 years. Neck and arm pain improved 60% and 79%, respectively, and NDI had an improvement of 58%. There were no episodes of device migration or subsidence. Mean ROM of the device was 6.4°. Heterotopic ossification was present in seven patients (37%). Radiographic ASD below the device developed in four patients (21%) (one single-level and three two-level ADR). No patient required secondary surgery (repeat operations at the index level or adjacent levels). Fourteen out of 19 patients (74%) were able to return to employment, with a median return to work time of 1.3 months. The ProDisc-C device for cervical ADR is a safe option for patients providing excellent clinical outcomes, satisfactory return to work rates and maintenance of segmental motion despite radiographic evidence of heterotopic ossification and ASD on long-term follow-up. PMID:24417795

  15. Vertebral body split fracture after a single-level cervical total disc replacement.

    PubMed

    Tu, Tsung-Hsi; Wu, Jau-Ching; Fay, Li-Yu; Ko, Chin-Chu; Huang, Wen-Cheng; Cheng, Henrich

    2012-03-01

    Cervical total disc replacement (TDR) is a viable option for the surgical treatment of degenerative disc disease. This 67-year-old nonsmoking male patient underwent single-level ProDisc-C cervical TDR at C5-6 without any intraoperative problem. His radicular pain improved and he had no neck pain immediately after the operation. However, on postoperative Day 3, a radiograph demonstrated a vertical split fracture of the C-5 vertebra. This fracture was managed conservatively, and 2 years postoperatively a follow-up CT scan demonstrated stable device position and fusion of the fracture. Although the linear fracture caused no neurological symptoms or device migration, the authors advocate prudence in selection and installation of keel-design prostheses, even in a single-level cervical TDR scenario. PMID:22176434

  16. Cervical Footprint Anthropometry in Indian Population: Implications on Design of Artificial Disc Replacement Devices

    PubMed Central

    Patil, Vishwanath Mahabaleshwar; Bangalore, Shashidhar Kantharajanna; Saraf, Abhishek

    2016-01-01

    Study Design Cross-sectional study. Purpose To accurately measure the dimensions of cervical endplates based on computed tomography (CT) scans in Indian population and assess accuracy of match with currently available cervical disc prostheses. Overview of Literature The dimensions of currently available cervical disc replacement implants are based on early published geometrical measurements of vertebrae endplates for Caucasian population. To author's knowledge, similar study has not been published for patients from Indian subcontinent. Methods CT scans of cervical spine of patients from Indian subcontinent were collected and reviewed. Seventy patients (54 men and 16 women; aged 18–56 years with average of 37 years) who underwent CT scans of cervical spine were included in study. 3D CT scans of sub axial cervical spine (C3 to C7) were analyzed. The anterior-posterior (AP) and central mediolateral (CML) dimensions of superior and inferior endplates from C3 to C7 were measured using digital measuring system. Results A total of 560 endplates of 70 patients were included in the study. The AP diameter of cervical endplates ranged from 0.87 to 2.47 cm. The CML diameters ranged from 0.84 to 2.98 cm. For levels C3/C4 and C4/C5 for AP dimension Prestige-LP (90.5%) and Prodisc-C (89%) discs showed higher percentage of matching than Discover discs (58.5%). For CML diameter, Prestige-LP (69.5%), Prodisc-C (70%) and Discover (39.5%) discs showed almost similar matching with measured endplates. For levels C5/C6 and C6/C7 for AP dimension, Prestige-LP (67.25%), Prodisc-C (49.35%) and Discover (51.5%) discs showed similar matching. For CML diameter Prestige-LP (32%), Prodisc-C (27.5%) and Discover (42.2%) discs showed poor matching with measured endplates. Conclusions This study indicates need for redesign of cervical disc prostheses to match Indian patients. The collected anthropometric dimensions from this study may be used to design and develop indigenous artificial total disc

  17. The Role of Posterior Longitudinal Ligament in Cervical Disc Replacement: An Ovine Cadaveric Biomechanical Analysis.

    PubMed

    Yu, Cheng-Cheng; Hao, Ding-Jun; Ma, Yu-Li; Huang, Da-Geng; Li, Hou-Kun; Feng, Hang; Hou, Qian

    2016-01-01

    BACKGROUND Cervical disc replacement (CDR) has been widely used to restore and maintain mobility and function of the treated and adjacent motion segments. Posterior longitudinal ligament (PLL) resection has been shown to be efficient in anterior cervical decompression and fusion. However, less is known about the biomechanical effect of PLL removal versus preservation in cervical disc arthroplasty. MATERIAL AND METHODS Three motion segments of 24 ovine cervical spines (C2-C5) were evaluated in a robotic spine system with axial compressive loads of 50 N. These cervical spines were divided in three groups according to the following conditions: (1) intact spine, (2) C3/C4 CDR with the Prestige LP prosthesis and PLL preservation, and (3) C3/C4 CDR with the Prestige LP prosthesis and PLL removal. The ranges of motion (ROMs) were recorded and analyzed in each group. RESULTS The C3/C4 ROM in group 3 (CDR with PLL removed) increased significantly in flexion-extension and axial rotation compared with group 1 (intact spine). Moreover, in flexion-extension, the mean total ROM was significantly larger in group 3 than in group 1. All the ROM observed in group 2 (CDR with PLL preserved) did not significantly differ from the ROM observed in group 1. CONCLUSIONS Compared with intact spines, CDR with PLL removal partly increased ROM. Moreover, the ROM in CDR with PLL preservation did not significantly differ from the ROM observed in intact spines. The PLL appears to contribute to the balance and stability of the cervical spine and should thus be preserved in cervical disc replacement provided that the posterior longitudinal ligament is not degenerative and the compression can be removed without PLL takedown. PMID:27243444

  18. The Role of Posterior Longitudinal Ligament in Cervical Disc Replacement: An Ovine Cadaveric Biomechanical Analysis

    PubMed Central

    Yu, Cheng-Cheng; Hao, Ding-Jun; Ma, Yu-Li; Huang, Da-Geng; Li, Hou-Kun; Feng, Hang; Hou, Qian

    2016-01-01

    Background Cervical disc replacement (CDR) has been widely used to restore and maintain mobility and function of the treated and adjacent motion segments. Posterior longitudinal ligament (PLL) resection has been shown to be efficient in anterior cervical decompression and fusion. However, less is known about the biomechanical effect of PLL removal versus preservation in cervical disc arthroplasty. Material/Methods Three motion segments of 24 ovine cervical spines (C2–C5) were evaluated in a robotic spine system with axial compressive loads of 50 N. These cervical spines were divided in three groups according to the following conditions: (1) intact spine, (2) C3/C4 CDR with the Prestige LP prosthesis and PLL preservation, and (3) C3/C4 CDR with the Prestige LP prosthesis and PLL removal. The ranges of motion (ROMs) were recorded and analyzed in each group. Results The C3/C4 ROM in group 3 (CDR with PLL removed) increased significantly in flexion-extension and axial rotation compared with group 1 (intact spine). Moreover, in flexion-extension, the mean total ROM was significantly larger in group 3 than in group 1. All the ROM observed in group 2 (CDR with PLL preserved) did not significantly differ from the ROM observed in group 1. Conclusions Compared with intact spines, CDR with PLL removal partly increased ROM. Moreover, the ROM in CDR with PLL preservation did not significantly differ from the ROM observed in intact spines. The PLL appears to contribute to the balance and stability of the cervical spine and should thus be preserved in cervical disc replacement provided that the posterior longitudinal ligament is not degenerative and the compression can be removed without PLL takedown. PMID:27243444

  19. A compliant-mechanism approach to achieving specific quality of motion in a lumbar total disc replacement

    PubMed Central

    Halverson, Peter A.; Bowden, Anton E.; Howell, Larry L.

    2012-01-01

    Background The current generation of total disc replacements achieves excellent short- and medium-term results by focusing on restoring the quantity of motion. Recent studies indicate that additional concerns (helical axes of motion, segmental torque-rotation behavior) may have important implications in the health of adjacent segments as well as the health of the surrounding tissue of the operative level. The objective of this article is to outline the development, validation, and biomechanical performance of a novel, compliant-mechanism total disc replacement that addresses these concerns by including them as essential design criteria. Methods Compliant-mechanism design techniques were used to design a total disc replacement capable of replicating the moment-rotation response and the location and path of the helical axis of motion. A prototype was evaluated with the use of bench-top testing and single-level cadaveric experiments in flexion-extension, lateral bending, and axial torsion. Results Bench-top testing confirmed that the moment-rotation response of the disc replacement matched the intended design behavior. Cadaveric testing confirmed that the moment-rotation and displacement response of the implanted segment mimicked those of the healthy spinal segment. Conclusions Incorporation of segmental quality of motion into the foundational stages of the design process resulted in a total disc replacement design that provides torque-rotation and helical axis–of–motion characteristics to the adjacent segments and the operative-level facets that are similar to those observed in healthy spinal segments. PMID:25694875

  20. Challenges and pitfalls when implementing renal replacement therapy in the ICU

    PubMed Central

    2015-01-01

    Several new methods of renal replacement therapy (RRT) are now available for treating patients in the ICU setting. However, utilization of RRT in the ICU is subject to considerable variation and the need for RRT is associated with worse outcomes. Several factors influence the application of dialysis and reflect the interplay of patient and process of care elements that are dynamic in nature. Despite multiple studies evaluating RRT and its application, there are gaps in our knowledge that must be overcome to improve outcomes. This article discusses some of the important issues that require attention in delivering RRT in critically ill patients and provides a framework for the optimal use of RRT in the ICU. PMID:26729322

  1. Severe Impingement of Lumbar Disc Replacements Increases the Functional Biological Activity of Polyethylene Wear Debris

    PubMed Central

    Baxter, Ryan M.; MacDonald, Daniel W.; Kurtz, Steven M.; Steinbeck, Marla J.

    2013-01-01

    Background: Wear, oxidation, and particularly rim impingement damage of ultra-high molecular weight polyethylene total disc replacement components have been observed following surgical revision. However, neither in vitro testing nor retrieval-based evidence has shown the effect(s) of impingement on the characteristics of polyethylene wear debris. Thus, we sought to determine (1) differences in polyethylene particle size, shape, number, or biological activity that correspond to mild or severe rim impingement and (2) in an analysis of all total disc replacements, regardless of impingement classification, whether there are correlations between the extent of regional damage and the characteristics of polyethylene wear debris. Methods: The extent of dome and rim damage was characterized for eleven retrieved polyethylene cores obtained at revision surgery after an average duration of implantation of 9.7 years (range, 4.6 to 16.1 years). Polyethylene wear debris was isolated from periprosthetic tissues with use of nitric acid and was imaged with use of environmental scanning electron microscopy. Subsequently, particle size, shape, number, biological activity, and chronic inflammation scores were determined. Results: Grouping of particles by size ranges that represented high biological relevance (<0.1 to 1-μm particles), intermediate biological relevance (1 to 10-μm particles), and low biological relevance (>10-μm particles) revealed an increased volume fraction of particles in the <0.1 to 1-μm and 1 to 10-μm size ranges in the mild-impingement cohort as compared with the severe-impingement cohort. The increased volume fractions resulted in a higher specific biological activity per unit particle volume in the mild-impingement cohort than in the severe-impingement cohort. However, functional biological activity, which is normalized by particle volume (mm3/g of tissue), was significantly higher in the severe-impingement cohort. This increase was due to a larger volume

  2. [Degenerative disorders of the lumbar spine Total disc replacement as an alternative to lumbar fusion?].

    PubMed

    Mayer, H M

    2005-10-01

    Spinal fusion is accepted worldwide as a therapeutic option for the treatment of degenerative disorders of the lumbar spine. Because there are only few evidence-based data available supporting the usefulness of lumbar spinal fusion, its questionable benefit as well as the potential for complications are the reasons for an ongoing discussion. In recent years, total disc replacement with implants has emerged as an alternative treatment. Although early results are promising, there is still a lack of evidence-based data as well as of long-term results for this technology. This article gives a critical update on the implant systems currently in use (SB Charité, Prodisc II L, Maverick, Flexicore, Mobidisc), which all have to be considered as "first-generation" implants. Morphological and clinical sequelae of the different biomechanical properties, designs, and materials have not yet been sufficiently investigated. There is no international consensus on the indication spectrum and on the preoperative diagnosis of discogenic low back pain. The same is true for the (minimally invasive) surgical access strategies. Complication rates seem to be somewhat lower compared to spinal fusion techniques. There are no standardized revision concepts in cases of implant failure. Lumbar disc replacement has opened a new era in spinal surgery with a still unproven benefit for the patient. It is strongly recommended that these techniques should only be applied by experienced and well-trained spine surgeons. Until evidence-based data are available, all patients should be treated under scientific study conditions with close postoperative follow-up. PMID:16034627

  3. The Incidence of Potential Candidates for Total Disc Replacement among Lumbar and Cervical Fusion Patient Populations

    PubMed Central

    Goldstein, Jeffrey A.; Bendo, John A.; Kim, Yong; Spivak, Jeffrey M.

    2011-01-01

    Study Design Retrospective chart review. Purpose To evaluate the incidence of potential total disc replacement (TDR) candidates among cervical and lumbar fusion patient populations using strict Food and Drug Administration (FDA) criteria and with relative exclusion criteria removed. Overview of Literature Recent studies suggest that the potential percentage of patients that are candidates for TDR ranges from 0-5% in lumbar fusions and 43% in cervical fusions. Methods We performed a retrospective chart review of 280 consecutive patients who had lumbar (n = 174) and cervical (n = 106) fusion or TDR performed by one of four independent adult orthopaedic spine surgeons. Charts were screened for investigational device exemption (IDE) inclusion/exclusion criteria and later reanalyzed excluding relative exclusion criteria, such as history of chronic medical illness, twolevel disease (cervical cases), and history of prior fusion surgery in the anatomic region. Results Of the 174 lumbar surgeries, 10 were TDR with Prodisc-L and 164 were lumbar fusions. The most common TDR exclusion criteria were lytic spondylolisthesis or spinal stenosis (47.7% of patients) and more than 2 level degenerative disc disease (37.9%). 14.9% had no IDE exclusion criteria and would be considered candidates for TDR. After excluding the relative lumbar exclusion criteria, this percentage increased to 25.8%. Of the 106 cervical cases, 3 had a TDR with Prodisc-C and 103 had a cervical fusion. Twenty eight percent had no IDE exclusion criteria and would be considered candidates for cervical TDR. Conclusions A larger percentage of cervical fusion candidates are potential candidates for TDR (28%) than lumbar fusion candidates (14.9%) based on the strict IDE criteria. PMID:22164315

  4. Wear simulation of a polyethylene-on-metal cervical total disc replacement under different concentrations of bovine serum lubricant.

    PubMed

    Hyde, P J; Fisher, J; Hall, R M

    2016-05-01

    Metal-on-polyethylene total disc replacements have been an alternative to spinal fusion in the lumbar spine under certain indications for more than a decade. Recently, cervical total disc replacement has also become an alternative to cervical fusion. Knowledge acquired from years of in vitro simulator studies on other joint replacements has highlighted the risks associated with premature wear due to unforeseen adverse clinical conditions and the effect of particulate debris on surrounding natural tissues. Having no evidence of the type and composition of the lubricating fluid that will result after spinal arthroplasty, a study on the effects of lubricant serum concentration was undertaken. The wear rate was shown to be inversely proportional to protein content of the serum over a range of 50%-3% bovine serum to water concentration. PMID:27160565

  5. Assessment of non-contacting optical methods to measure wear and surface roughness in ceramic total disc replacements.

    PubMed

    Green, Naomi C; Bowen, James; Hukins, David W L; Shepherd, Duncan E T

    2015-03-01

    This study presents a method for measuring the low volumetric wear expected in ceramic total disc replacements, which can be used to replace intervertebral discs in the spine, using non-contacting optical methods. Alumina-on-alumina ball-on-disc tests were conducted with test conditions approximating those of cervical (neck region of the spine) total disc replacement wear tests. The samples were then scanned using a three-dimensional non-contacting optical profilometer and the data used to measure surface roughness and develop a method for measuring the wear volume. The results showed that the magnification of the optical lens affected the accuracy of both the surface roughness and wear volume measurements. The method was able to successfully measure wear volumes of 0.0001 mm(3), which corresponds to a mass of 0.0001 mg, which would have been undetectable using the gravimetric method. A further advantage of this method is that with one scan the user can measure changes in surface topography, volumetric wear and the location of the wear on the implant surface. This method could also be applied to more severe wear, other types of orthopaedic implants and different materials. PMID:25834000

  6. Preferential superior surface motion in wear simulations of the Charité total disc replacement.

    PubMed

    Goreham-Voss, Curtis M; Vicars, Rachel; Hall, Richard M; Brown, Thomas D

    2012-06-01

    Laboratory wear simulations of the dual-bearing surface Charité total disc replacement (TDR) are complicated by the non-specificity of the device's center of rotation (CoR). Previous studies have suggested that articulation of the Charité preferentially occurs at the superior-bearing surface, although it is not clear how sensitive this phenomenon is to lubrication conditions or CoR location. In this study, a computational wear model is used to study the articulation kinematics and wear of the Charité TDR. Implant wear was found to be insensitive to the CoR location, although seemingly non-physiologic endplate motion can result. Articulation and wear were biased significantly to the superior-bearing surface, even in the presence of significant perturbations of loading and friction. The computational wear model provides novel insight into the mechanics and wear of the Charité TDR, allowing for better interpretation of in vivo results, and giving useful insight for designing future laboratory physical tests. PMID:20582556

  7. Indications for Lumbar Total Disc Replacement: Selecting the Right Patient with the Right Indication for the Right Total Disc

    PubMed Central

    Guyer, Richard D.; Ohnmeiss, Donna D.

    2014-01-01

    Summary of Background Data As with any surgery, care should be taken to determine patient selection criteria for lumbar TDR based on safety and optimizing outcome. These goals may initially be addressed by analyzing biomechanical implant function and early clinical experience, ongoing evaluation is needed to refine indications. Objective The purpose of this work was to synthesize information published on general indications for lumbar TDR. A secondary objective was to determine if indications vary for different TDR designs. Methods A comprehensive literature search was conducted to identify lumbar TDR articles. Articles were reviewed and patient selection criteria and indications were synthesized. Results With respect to safety, there was good agreement in the literature to exclude patients with osteopenia/osteoporosis or fracture. Risk of injury to vascular structures due to the anterior approach was often addressed by excluding patients with previous abdominal surgery in the area of disc pathology or increased age. The literature was very consistent on the primary indication for TDR being painful disc degeneration unresponsive to at least 6 months of nonoperative care. Literature investigating the impact of previous spine surgery was mixed; however, prior surgery was not necessarily a contra-indication, provided the patient otherwise met selection criteria. The literature was mixed on setting a minimum preoperative disc height as a selection criterion. There were no publications investigating whether some patients are better/worse candidates for specific TDR designs. Based on the literature a proposal for patient selection criteria is offered. Conclusions Several TDR indications and contra-indications are widely accepted. No literature addresses particular TDR design being preferable for some patients. As with any spine surgery, ongoing evaluation of TDR outcomes will likely lead to more detailed general and device design specific indications. PMID:25694946

  8. Total lumbar disc replacement in athletes: clinical results, return to sport and athletic performance

    PubMed Central

    Wiechert, Karsten; Khattab, Mohamed F.; Korge, Andreas; Mayer, H. Michael

    2007-01-01

    Despite the increasing popularity of total lumbar disc replacement (TDR) in predominantly young and active patients, no previous study has addressed possibilities, limitations and potential risks regarding athletic performance following TDR. Mechanical concerns remain and the implant’s resilience as regards its load-bearing capacity during sporting activities is unknown. Thirty-nine athletic patients fulfilled the inclusion criteria for this study. These patients participated in a large variety of different types of sport. Significant and lasting pain-relief was attained following TDR with a mean follow-up of 26.3 months (range 9–50.7 months; FU rate 97.4%). Sporting activity was resumed within the first 3 months (38.5%) to 6 months (30.7%) with peak performance being reached after 5.2 months. Thirty-seven patients (94.9%) achieved resumption of sporting activity. Athletic performance improved significantly in 33 patients (84.6%). Minor subsidence was observed in 13 patients (30%) within the first 3 months with no further implant migration thereafter in 12 patients. Participation in all types of sport recorded in this study was accessible for a high rate of patients up to the level of professional athletes as well as those participating in extreme sports. Preoperative participation in sport proved to be a strong positive predictor for highly satisfactory postoperative outcome following TDR. In a selected group of patients, however, preoperative inability to participate in sporting activities did not impair postoperative physical activity. Due to the young age of the patients and significant load increase exerted during athletic activities, persisting concerns regarding the future behaviour of the implant remain and will require longer follow-up, modified investigation techniques and larger patient cohorts. PMID:17205239

  9. Seven-year cost-effectiveness of ProDisc-C total disc replacement: results from investigational device exemption and post-approval studies.

    PubMed

    Radcliff, Kris; Lerner, Jason; Yang, Chao; Bernard, Thierry; Zigler, Jack E

    2016-05-01

    OBJECTIVE The purpose of this study was to evaluate the 7-year cost-effectiveness of cervical total disc replacement (CTDR) versus anterior cervical discectomy and fusion (ACDF) for the treatment of patients with single-level symptomatic degenerative disc disease. A change in the spending trajectory for spine care is to be achieved, in part, through the selection of interventions that have been proven effective yet cost less than other options. This analysis complements and builds upon findings from other cost-effectiveness evaluations of CTDR through the use of long-term, patient-level data from a randomized study. METHODS This was a 7-year health economic evaluation comparing CTDR versus ACDF from the US commercial payer perspective. Prospectively collected health care resource utilization and treatment effects (quality-adjusted life years [QALYs]) were obtained from individual patient-level adverse event reports and SF-36 data, respectively, from the randomized, multicenter ProDisc-C total disc replacement investigational device exemption (IDE) study and post-approval study. Statistical distributions for unit costs were derived from a commercial claims database and applied using Monte Carlo simulation. Patient-level costs and effects were modeled via multivariate probabilistic analysis. Confidence intervals for 7-year costs, effects, and net monetary benefit (NMB) were obtained using the nonparametric percentile method from results of 10,000 bootstrap simulations. The robustness of results was assessed through scenario analysis and within a parametric regression model controlling for baseline variables. RESULTS Seven-year follow-up data were available for more than 70% of the 209 randomized patients. In the base-case analysis, CTDR resulted in mean per-patient cost savings of $12,789 (95% CI $5362-$20,856) and per-patient QALY gains of 0.16 (95% CI -0.073 to 0.39) compared with ACDF over 7 years. CTDR was more effective and less costly in 90.8% of probabilistic

  10. Biomechanical Analysis of a Novel Prosthesis Based on the Physiological Curvature of Endplate for Cervical Disc Replacement

    PubMed Central

    Yu, Cheng-Cheng; Hao, Ding-Jun; Huang, Da-Geng; Qian, Li-Xiong; Feng, Hang; Li, Hou-Kun; Zhao, Song-Chuan

    2016-01-01

    Study Design Biomechanical analysis of a novel prosthesis based on the physiological curvature of endplate was performed. Objective To compare the biomechanical differences between a novel prosthesis based on the physiological curvature of the endplate and the Prestige LP prosthesis after cervical disc replacement (CDR). Summary of Background Data Artificial disc prostheses have been widely used to preserve the physiological function of treated and adjacent motion segments in CDR, while most of those present a flat surface instead of an arcuate surface which approximately similar to anatomic structures in vivo. We first reported a well-designed artificial disc prosthesis based on the physiological curvature of the endplate. Methods Three motion segments of 24 ovine cervical spines (C2-5) were evaluated in a robotic spine system with axial compressive loads of 50N. Testing conditions were as follows: 1) intact, 2) C3–4 CDR with artificial disc prosthesis based on the physiological curvature of the endplate, and 3) C3–4 CDR with the Prestige LP prosthesis. The range of motion (ROM) and the pressures on the inferior surface of the two prostheses were recorded and analyzed. Results As compared to the intact state, the ROM of all three segments had no significant difference in the replacement group. Additionally, there was no significant difference in ROM between the two prostheses. The mean pressure on the novel prosthesis was significantly less than the Prestige LP prosthesis. Conclusion ROM in 3 groups (intact group, CDR group with novel prosthesis and CDR group with Prestige LP) showed no significant difference. The mean pressure on the inferior surface of the novel prosthesis was significantly lower than the Prestige LP prosthesis. Therefore, the novel artificial disc prosthesis is feasible and effective, and can reduce the implant-bone interface pressure on the endplate, which may be one possible reason of prosthesis subsidence. PMID:27355319

  11. Biomechanics of Hybrid Anterior Cervical Fusion and Artificial Disc Replacement in 3-Level Constructs: An In Vitro Investigation

    PubMed Central

    Liao, Zhenhua; Fogel, Guy R.; Pu, Ting; Gu, Hongsheng; Liu, Weiqiang

    2015-01-01

    Background The ideal surgical approach for cervical disk disease remains controversial, especially for multilevel cervical disease. The purpose of this study was to investigate the biomechanics of the cervical spine after 3-level hybrid surgery compared with 3-level anterior cervical discectomy and fusion (ACDF). Material/Methods Eighteen human cadaveric spines (C2-T1) were evaluated under displacement-input protocol. After intact testing, a simulated hybrid construct or fusion construct was created between C3 to C6 and tested in the following 3 conditions: 3-level disc plate disc (3DPD), 3-level plate disc plate (3PDP), and 3-level plate (3P). Results Compared to intact, almost 65~80% of motion was successfully restricted at C3-C6 fusion levels (p<0.05). 3DPD construct resulted in slight increase at the 3 instrumented levels (p>0.05). 3PDP construct resulted in significant decrease of ROM at C3-C6 levels less than 3P (p<0.05). Both 3DPD and 3PDP caused significant reduction of ROM at the arthrodesis level and produced motion increase at the arthroplasty level. For adjacent levels, 3P resulted in markedly increased contribution of both upper and lower adjacent levels (p<0.05). Significant motion increases lower than 3P were only noted at partly adjacent levels in some conditions for 3DPD and 3PDP (p<0.05). Conclusions ACDF eliminated motion within the construct and greatly increased adjacent motion. Artificial cervical disc replacement normalized motion of its segment and adjacent segments. While hybrid conditions failed to restore normal motion within the construct, they significantly normalized motion in adjacent segments compared with the 3-level ACDF condition. The artificial disc in 3-level constructs has biomechanical advantages compared to fusion in normalizing motion. PMID:26529430

  12. Cervical Total Disc Replacement is Superior to Anterior Cervical Decompression and Fusion: A Meta-Analysis of Prospective Randomized Controlled Trials

    PubMed Central

    Zhang, Yujie; Liang, Chengzhen; Tao, Yiqing; Zhou, Xiaopeng; Li, Hao; Li, Fangcai; Chen, Qixin

    2015-01-01

    Background Despite being considered the standard surgical procedure for symptomatic cervical disc disease, anterior cervical decompression and fusion invariably accelerates adjacent segment degeneration. Cervical total disc replacement is a motion-preserving procedure developed as a substitute to fusion. Whether cervical total disc replacement is superior to fusion remains unclear. Methods We comprehensively searched PubMed, EMBASE, Medline, and the Cochrane Library in accordance with the inclusion criteria to identify possible studies. The retrieved results were last updated on December 12, 2014. We classified the studies as short-term and midterm follow-up. Results Nineteen randomized controlled trials involving 4516 cases were identified. Compared with anterior cervical decompression and fusion, cervical total disc replacement had better functional outcomes (neck disability index [NDI], NDI success, neurological success, neck pain scores reported on a numerical rating scale [NRS], visual analog scales scores and overall success), greater segmental motion at the index level, fewer adverse events and fewer secondary surgical procedures at the index and adjacent levels in short-term follow-up (P < 0.05). With midterm follow-up, the cervical total disc replacement group indicated superiority in the NDI, neurological success, pain assessment (NRS), and secondary surgical procedures at the index level (P < 0.05). The Short Form 36 (SF-36) and segmental motion at the adjacent level in the short-term follow-up showed no significant difference between the two procedures, as did the secondary surgical procedure rates at the adjacent level with midterm follow-up (P > 0.05). Conclusions Cervical total disc replacement presented favorable functional outcomes, fewer adverse events, and fewer secondary surgical procedures. The efficacy and safety of cervical total disc replacement are superior to those of fusion. Longer-term, multicenter studies are required for a better

  13. Clinical and radiologic comparison of dynamic cervical implant arthroplasty and cervical total disc replacement for single-level cervical degenerative disc disease.

    PubMed

    Shichang, Liu; Yueming, Song; Limin, Liu; Lei, Wang; Zhongjie, Zhou; Chunguang, Zhou; Xi, Yang

    2016-05-01

    Anterior cervical discectomy and fusion, to date the most successful spine procedure for the surgical treatment of cervical radiculopathy, has limitations that have led to the development of non-fusion cervical procedures, such as cervical total disc replacement (TDR) and dynamic cervical implant (DCI) arthroplasty. We compared the clinical and radiological results of DCI and cervical TDR for the treatment of single-level cervical degenerative disc disease in Chinese patients. A retrospective review of 179 patients with cervical spondylotic myelopathy who underwent DCI or TDR between April 2010 and October 2012 was conducted, and 152 consecutive patients (67 patients single-level DCI and 85 single-level TDR) who completed at least 2years of follow-up were included. Clinical and radiological assessments were performed preoperatively and at 1week and 3, 6, 12, and 24months postoperatively. The most common operative level was C5/C6 (49.3%). The differences in blood loss, duration of surgery, and duration of hospitalization were not statistically significant. The Japanese Orthopaedic Association scale, Visual Analog Scale, Neck Disability Index, and Short Form-36 scores improved significantly after surgery in both the DCI and TDR groups (P<0.05), but the differences were not statistically significant at the final follow-up. The rate of occurrence of heterotopic ossification was 22.4% and 28.2% in the DCI and TDR groups, respectively. As an effective non-fusion technique, DCI is a more economical procedure. Further prospective, randomized studies with long-term follow-up periods are needed to determine the long-term effects. PMID:26928156

  14. Five-year clinical results of cervical total disc replacement compared with anterior discectomy and fusion for treatment of 2-level symptomatic degenerative disc disease: a prospective, randomized, controlled, multicenter investigational device exemption clinical trial.

    PubMed

    Radcliff, Kris; Coric, Domagoj; Albert, Todd

    2016-08-01

    OBJECTIVE The purpose of this study was to report the outcome of a study of 2-level cervical total disc replacement (Mobi-C) versus anterior cervical discectomy and fusion (ACDF). Although the long-term outcome of single-level disc replacement has been extensively described, there have not been previous reports of the 5-year outcome of 2-level cervical disc replacement. METHODS This study reports the 5-year results of a prospective, randomized US FDA investigational device exemption (IDE) study conducted at 24 centers in patients with 2-level, contiguous, cervical spondylosis. Clinical outcomes at up to 60 months were evaluated, including validated outcome measures, incidence of reoperation, and adverse events. The complete study data and methodology were critically reviewed by 3 independent surgeon authors without affiliation with the IDE study or financial or institutional bias toward the study sponsor. RESULTS A total of 225 patients received the Mobi-C cervical total disc replacement device and 105 patients received ACDF. The Mobi-C and ACDF follow-up rates were 90.7% and 86.7%, respectively (p = 0.39), at 60 months. There was significant improvement in all outcome scores relative to baseline at all time points. The Mobi-C patients had significantly more improvement than ACDF patients in terms of Neck Disability Index score, SF-12 Physical Component Summary, and overall satisfaction with treatment at 60 months. The reoperation rate was significantly lower with Mobi-C (4%) versus ACDF (16%). There were no significant differences in the adverse event rate between groups. CONCLUSIONS Both cervical total disc replacement and ACDF significantly improved general and disease-specific measures compared with baseline. However, there was significantly greater improvement in general and disease-specific outcome measures and a lower rate of reoperation in the 2-level disc replacement patients versus ACDF control patients. Clinical trial registration no. NCT00389597

  15. Positive Pitfalls

    ERIC Educational Resources Information Center

    Schneider, Michael

    2004-01-01

    This article describes how Cahokia middle and high school students conduct inquiry-based science through a pitfall trap experiment. In a collaborative effort, students designed and conducted pitfall trap investigations that combined their interest in the natural world with their love of technology. The students set up their own experiments to…

  16. Biomechanics of Artificial Disc Replacements Adjacent to a 2-Level Fusion in 4-Level Hybrid Constructs: An In Vitro Investigation.

    PubMed

    Liao, Zhenhua; Fogel, Guy R; Wei, Na; Gu, Hongsheng; Liu, Weiqiang

    2015-01-01

    BACKGROUND The ideal procedure for multilevel cervical degenerative disc diseases remains controversial. Recent studies on hybrid surgery combining anterior cervical discectomy and fusion (ACDF) and artificial cervical disc replacement (ACDR) for 2-level and 3-level constructs have been reported in the literature. The purpose of this study was to estimate the biomechanics of 3 kinds of 4-level hybrid constructs, which are more likely to be used clinically compared to 4-level arthrodesis. MATERIAL AND METHODS Eighteen human cadaveric spines (C2-T1) were evaluated in different testing conditions: intact, with 3 kinds of 4-level hybrid constructs (hybrid C3-4 ACDR+C4-6 ACDF+C6-7ACDR; hybrid C3-5ACDF+C5-6ACDR+C6-7ACDR; hybrid C3-4ACDR+C4-5ACDR+C5-7ACDF); and 4-level fusion. RESULTS Four-level fusion resulted in significant decrease in the C3-C7 ROM compared with the intact spine. The 3 different 4-level hybrid treatment groups caused only slight change at the instrumented levels compared to intact except for flexion. At the adjacent levels, 4-level fusion resulted in significant increase of contribution of both upper and lower adjacent levels. However, for the 3 hybrid constructs, significant changes of motion increase far lower than 4P at adjacent levels were only noted in partial loading conditions. No destabilizing effect or hypermobility were observed in any 4-level hybrid construct. CONCLUSIONS Four-level fusion significantly eliminated motion within the construct and increased motion at the adjacent segments. For all 3 different 4-level hybrid constructs, ACDR normalized motion of the index segment and adjacent segments with no significant hypermobility. Compared with the 4-level ACDF condition, the artificial discs in 4-level hybrid constructs had biomechanical advantages compared to fusion in normalizing adjacent level motion. PMID:26694835

  17. The effect of lumbar total disc replacement on the spinopelvic alignment and range of motion of the lumbar spine.

    PubMed

    Chung, Sung Soo; Lee, Chong Suh; Kang, Chang Seok; Kim, Sang Hyun

    2006-07-01

    A lumbar total disc replacement (TDR) is a type of motion-preserving surgery, which aims to restore and maintain the normal range of motion (ROM) and the sagittal balance of the spine. However, little is known regarding how the spinopelvic alignment and ROM of the lumbar spine are influenced by the lumbar TDR with ProDisc. This study retrospectively analyzed the sagittal alignment and ROM of the lumbar spine in 26 consecutive patients who had undergone the TDR with ProDisc with a minimum follow-up of 24 months. A standing lateral radiograph, which included the femoral heads and dynamic flexion-extension lateral radiographs of the spine were taken before surgery and at the follow-up visit. The radiological parameters included the sacral tilt, the pelvic tilt, and the lumbar lordosis. The segmental lordosis and ROM were also measured at each operative level. Nineteen patients underwent a single-level TDR and 7 patients underwent a double-level TDR. The mean lumbar lordosis increased significantly from 30.5 degrees to 40.8 degrees in all patients who underwent TDR without any significant changes in the sacral tilt and pelvic tilt at the latest follow-up (P<0.05). In the patients who underwent single-level TDR, the mean segmental lordosis at the L5-S1 and L4-5 operative levels increased significantly from 15.8 degrees to 23.2 degrees and from 14.1 degrees to 24.9 degrees, respectively. The mean ROM at L5-S1 and L4-5 increased significantly from 7.1 degrees to 11.2 degrees and from 11.4 degrees to 14.6 degrees, respectively. The sagittal balance and ROM of the lumbar spine improved significantly after the lumbar TDR. PMID:16825999

  18. Biomechanics of Artificial Disc Replacements Adjacent to a 2-Level Fusion in 4-Level Hybrid Constructs: An In Vitro Investigation

    PubMed Central

    Liao, Zhenhua; Fogel, Guy R.; Wei, Na; Gu, Hongsheng; Liu, Weiqiang

    2015-01-01

    Background The ideal procedure for multilevel cervical degenerative disc diseases remains controversial. Recent studies on hybrid surgery combining anterior cervical discectomy and fusion (ACDF) and artificial cervical disc replacement (ACDR) for 2-level and 3-level constructs have been reported in the literature. The purpose of this study was to estimate the biomechanics of 3 kinds of 4-level hybrid constructs, which are more likely to be used clinically compared to 4-level arthrodesis. Material/Methods Eighteen human cadaveric spines (C2–T1) were evaluated in different testing conditions: intact, with 3 kinds of 4-level hybrid constructs (hybrid C3–4 ACDR+C4–6 ACDF+C6–7ACDR; hybrid C3–5ACDF+C5–6ACDR+C6–7ACDR; hybrid C3–4ACDR+C4–5ACDR+C5–7ACDF); and 4-level fusion. Results Four-level fusion resulted in significant decrease in the C3–C7 ROM compared with the intact spine. The 3 different 4-level hybrid treatment groups caused only slight change at the instrumented levels compared to intact except for flexion. At the adjacent levels, 4-level fusion resulted in significant increase of contribution of both upper and lower adjacent levels. However, for the 3 hybrid constructs, significant changes of motion increase far lower than 4P at adjacent levels were only noted in partial loading conditions. No destabilizing effect or hypermobility were observed in any 4-level hybrid construct. Conclusions Four-level fusion significantly eliminated motion within the construct and increased motion at the adjacent segments. For all 3 different 4-level hybrid constructs, ACDR normalized motion of the index segment and adjacent segments with no significant hypermobility. Compared with the 4-level ACDF condition, the artificial discs in 4-level hybrid constructs had biomechanical advantages compared to fusion in normalizing adjacent level motion. PMID:26694835

  19. Clinical outcomes of single-level lumbar artificial disc replacement compared with transforaminal lumbar interbody fusion in an Asian population

    PubMed Central

    Lee, Wei Ting; Liu, Gabriel; Thambiah, Joseph; Wong, Hee Kit

    2015-01-01

    INTRODUCTION The objective of this study was to examine the clinical outcome of single-level lumbar artificial disc replacement (ADR) compared to that of transforaminal lumbar interbody fusion (TLIF) for the treatment of symptomatic degenerative disc disease (DDD) in an Asian population. METHODS This was a retrospective review of 74 patients who had surgery performed for discogenic lower backs that involved only the L4/5 and L5/S1 levels. All the patients had lumbar DDD without radiculopathy or spondylolithesis, and concordant pain with discogram at the pathological level. The patients were divided into two groups – those who underwent ADR and those who underwent TLIF. RESULTS A trend suggesting that the ADR group had better perioperative outcomes (less blood loss, shorter operating time, shorter hospital stay and shorter time to ambulation) than the TLIF group was observed. However, a trend indicating that surgical-approach-related complications occurred more frequently in the ADR group than the TLIF group was also observed. The rate of revision surgery was comparable between the two groups. CONCLUSION Our findings suggest that for the treatment of discogenic lower back pain, lumbar ADR has better perioperative outcomes and a similar revision rate when compared with TLIF. However, the use of ADR was associated with a higher incidence of surgical-approach-related complications. More studies with bigger cohort sizes and longer follow-up periods are needed to determine the long-term efficacy and safety of ADR in lumbar DDD. PMID:25917472

  20. Comparison of 2-Level Versus 1-Level Total Disc Replacement: Results From a Prospective FDA-Regulated Trial

    PubMed Central

    Ohnmeiss, Donna D.

    2008-01-01

    Background Fusion has been the traditional surgery for painful disc degeneration unresponsive to nonoperative care. Fusion rates may decline in multilevel procedures. Also, fusion may force additional stress onto adjacent discs. This effect may be amplified in multilevel procedures. Single-level total disc replacement (TDR) has been found to be as effective as fusion. There have been few published reports addressing 2-level TDR. The purpose of this study was to compare results of TDR at 2 levels to 1-level procedures. Methods This report included the first consecutive 86 patients who had reached 24-month follow-up from among those enrolled in the ProDisc-L investigational device exemption (IDE) study of patients undergoing TDR at 1 level (N = 54) or at 2 levels (N = 32). Clinical outcome measures included visual analog scales (VAS) assessing pain, Oswestry Disability Index, satisfaction measured by VAS, and responses to the question regarding whether the patient would have the same surgery again. Results Operative time and length of hospitalization were significantly less in the 1-level cases compared to 2 levels (61.6 min vs 97.8 min; and 1.89 days vs 2.44 days; P < .05). There was a trend for less blood loss in single-level cases (59.0 mL vs 79.2 mL) (.05 < P < .09). VAS and Oswestry scores were significantly improved in both groups postoperatively (by approximately 50%). At no follow-up were there significant differences in VAS, Oswestry, or patient satisfaction scores between the single- and 2-level patients. At all follow-ups, the mean satisfaction in both groups was greater than 7.5 on a scale of 0 to 10. Conclusions Patients undergoing 2-level TDR improved significantly postoperatively based on VAS and Oswestry scores, and there were no significant differences in outcome scores when comparing 1- and 2-level TDR. Clinical Relevance This study suggests that 2-level TDR can be undertaken in appropriately selected patients and achieve results similar to

  1. Clinical results and development of heterotopic ossification in total cervical disc replacement during a 4-year follow-up

    PubMed Central

    Suchomel, Petr; Jurák, Lubomír; Brabec, Radim; Bradáč, Ondřej; Elgawhary, Shamel

    2009-01-01

    Cervical total disc replacement (CTDR) aims to decrease the incidence of adjacent segment disease through motion preservation in the operated disc space. Ongoing data collection and increasing number of studies describing heterotopic ossification (HO) resulting in decreased mobility of implants, forced us to carefully evaluate our long-term clinical and morphological results of patients with CTDR. We present the first 54 consecutive patients treated with 65 ProdiscC™ prostheses during a 12-month period (2/2004–3/2005). All patients signed an informed consent and were included in prospective long-term study approved by hospital ethical committee. The 1- and 2-year follow-up analysis were available for all patients included and 4-year results for 50 patients (60 implants). Clinical (neck disability index-NDI, visual analog scale-VAS) and radiological follow-up was conducted at 1-, 2- and 4-years after the procedure. The Mehren/Suchomel modification of McAfee scale was used to classify the appearance of HO. Mean preoperative NDI was 34.5%, VAS for neck pain intensity 4.6 and VAS for arm pain intensity 5.0. At 1-, 2- and 4-year follow-up, the mean NDI was 30.7, 27.2, and 30.4, mean VAS for neck pain intensity 2.5, 2.1 and 2.9 and mean VAS for arm pain intensity pain 2.2, 1.9 and 2.3, respectively. Significant HO (grade III) was present in 45% of implants and segmental ankylosis (grade IV) in another 18% 4 years after intervention. This finding had no clinical consequences and 92% of patients would undergo the same surgery again. Our clinical results (NDI, VAS) are comparable with fusion techniques. Although, advanced non-fusion technology is used, a significant frequency of HO formation and spontaneous fusion in cervical disc replacement surgery must be anticipated during long-term follow-up. PMID:20035357

  2. The importance of the anterior longitudinal ligament in lumbar disc arthroplasty: 36-Month follow-up experience in extreme lateral total disc replacement

    PubMed Central

    Marchi, Luis; Oliveira, Leonardo; Coutinho, Etevaldo; Pimenta, Luiz

    2012-01-01

    Background Current total disc replacement (TDR) for lumbar spine requires an anterior approach for implantation but presents inherent limitations, including risks to the abdominal structures, as well as resection of the anterior longitudinal ligament. By approaching the spine laterally, it is possible to preserve the stabilizing ligaments, which are a natural restraint to excessive rotations and translations, and thereby help to minimize facet stresses. This less invasive approach also offers a biomechanical advantage of placement of the device over the ring apophysis bilaterally; importantly, it also offers a greater opportunity for safer revision surgery, if necessary, by avoiding scarring of the anterior vasculature. We present the clinical and radiologic results of a lateral TDR device from a prospective single-center study. Methods A new metal-on-metal TDR device designed for implantation through a true lateral, retroperitoneal, transpsoatic approach (extreme lateral interbody fusion) was implanted in 36 patients with discography-confirmed 1- or 2-level degenerative disc disease. Clinical (pain and function) and radiographic (range of motion) outcome assessments were prospectively collected preoperatively, postoperatively, and serially up to a minimum of 36 months’ follow-up. Results Between December 2005 and December 2006, 36 surgeries were performed in 16 men and 20 women (mean age, 42.6 years). These included 15 single-level TDR procedures at L3-4 or L4-5, 3 2-level TDR procedures spanning L3-4 and L4-5, and 18 hybrid procedures (anterior lumbar interbody fusion) at L5-S1 and TDR at L4-5 (17) or L3-4 (1). Operative time averaged 130 minutes, with mean blood loss of 60 mL and no intraoperative complications. Postoperative X-rays showed good device placement, with restoration of disc height, foraminal volume, and sagittal balance. All patients were up and walking within 12 hours of surgery, and all but 9 were discharged the next day (7 of those 9 were

  3. In-situ photopolymerized and monitored implants: successful application to an intervertebral disc replacement

    NASA Astrophysics Data System (ADS)

    Schmocker, Andreas M.; Khoushabi, Azadeh; Bourban, Pierre-Etienne; Schizas, Constantin; Pioletti, Dominique; Moser, Christophe

    2016-02-01

    Photopolymerization is a common method to harden materials initially in a liquid state. A surgeon can directly trigger the solidification of a dental implant or a bone or tissue filler by using ultra-violet light. Traditionally, photopolymerization has been used mainly in dentistry. Over the last decade advances in material development including a wide range of biocompatible gel- and cement-systems open up a new avenue for in-situ photopolymerization. We designed a miniaturized light probe where a photoactive material can be 1) mixed, pressurized and injected 2) photopolymerized or photoactivated and 3) monitored during the chemical reaction. The device enables surgeries to be conducted through a hole smaller than 500 μm in diameter. Using a combination of Raman and fluorescence spectroscopy, the current state of the photopolymerization was inferred and monitored in real time within an in-vitro tissue model. It was also possible to determine roughly the position of the probe within the tissue cavity by analysing the fluorescence signal. Using the technique hydrogels were successfully implanted into a bovine intervertebral disc model. Mechanical tests could not obstruct the functionality of the implant. Finally, the device was also used for other application such as the implantation of a hydrogel into an aneurysm tissue cavity which will be presented at the conference.

  4. Quality of systematic reviews: an example of studies comparing artificial disc replacement with fusion in the cervical spine

    PubMed Central

    Tashani, Osama A.; El-Tumi, Hanan; Aneiba, Khaled

    2015-01-01

    Cervical artificial disc replacement (C-ADR) is now an alternative to anterior cervical discectomy and fusion (ACDF). Many studies have evaluated the efficacy of C-ADR compared with ACDF. This led to a series of systematic reviews and meta-analyses to evaluate the evidence of the superiority of one intervention against the other. The aim of the study presented here was to evaluate the quality of these reviews and meta-analyses. Medline via Ovid, Embase, and Cochrane Library were searched using the keywords: (total disk replacement, prosthesis, implantation, discectomy, and arthroplasty) AND (cervical vertebrae, cervical spine, and spine) AND (systematic reviews, reviews, and meta-analysis). Screening and data extraction were conducted by two reviewers independently. Two reviewers then assessed the quality of the selected reviews and meta-analysis using 11-item AMSTAR score which is a validated measurement tool to assess the methodological quality of systematic reviews. Screening of full reports of 46 relevant abstracts resulted in the selection of 15 systematic reviews and/or meta-analyses as eligible for this study. The two reviewers’ inter-rater agreement level was high as indicated by kappa of >0.72. The AMSTAR score of the reviews ranged from 3 to 11. Only one study (a Cochrane review) scored 100% (AMSTAR 11). Five studies scored below (AMSTAR 5) indicating low-quality reviews. The most significant drawbacks of reviews of a score below 5 were not using an extensive search strategy, failure to use the scientific quality of the included studies appropriately in formulating a conclusion, not assessing publication bias, and not reporting the excluded studies. With a significant exception of a Cochrane review, the methodological quality of systematic reviews evaluating the evidence of C-ADR versus ACDF has to be improved. PMID:26205640

  5. Wear of the Charité® lumbar intervertebral disc replacement investigated using an electro-mechanical spine simulator

    PubMed Central

    Moghadas, Parshia; Shepherd, Duncan ET; Hukins, David WL

    2015-01-01

    The Charité® lumbar intervertebral disc replacement was subjected to wear testing in an electro-mechanical spine simulator. Sinusoidally varying compression (0.6–2 kN, frequency 2 Hz), rotation (±2°, frequency 1 Hz), flexion–extension (6° to −3°, frequency 1 Hz) and lateral bending (±2°, frequency 1 Hz) were applied out of phase to specimens immersed in diluted calf serum at 37 °C. The mass of the ultra-high-molecular weight polyethylene component of the device was measured at intervals of 0.5, 1, 2, 3, 4 and 5 million cycles; its volume was also measured by micro-computed tomography. Total mass and volume losses were 60.3 ± 4.6 mg (mean ± standard deviation) and 64.6 ± 6.0 mm3. Corresponding wear rates were 12.0 ± 1.4 mg per million cycles and 12.8 ± 1.2 mm3 per million cycles; the rate of loss of volume corresponds to a mass loss of 11.9 ± 1.1 mg per million cycles, that is, the two sets of measurements of wear agree closely. Wear rates also agree closely with measurements made in another laboratory using the same protocol but using a conventional mechanical spine simulator. PMID:25834002

  6. Dynamic Biomechanical Examination of the Lumbar Spine with Implanted Total Disc Replacement (TDR) Utilizing a Pendulum Testing System

    PubMed Central

    Daniels, Alan H; Paller, David J; Koruprolu, Sarath; McDonnell, Matthew; Palumbo, Mark A; Crisco, Joseph J

    2013-01-01

    Study Design Biomechanical cadaver investigation Objective To examine dynamic bending stiffness and energy absorption of the lumbar spine with and without implanted Total Disc Replacement (TDR) under simulated physiologic motion. Summary of background data The pendulum testing system is capable of applying physiologic compressive loads without constraining motion of functional spinal units (FSUs). The number of cycles to equilibrium observed under pendulum testing is a measure of the energy absorbed by the FSU. Methods Five unembalmed, frozen human lumbar FSUs were tested on the pendulum system with axial compressive loads of 181N, 282N, 385N, and 488N before and after Synthes ProDisc-L TDR implantation. Testing in flexion, extension, and lateral bending began by rotating the pendulum to 5° resulting in unconstrained oscillatory motion. The number of rotations to equilibrium was recorded and bending stiffness (N-m/°) was calculated and compared for each testing mode. Results In flexion/extension, the TDR constructs reached equilibrium with significantly (p<0.05) fewer cycles than the intact FSU with compressive loads of 282N, 385N and 488N. Mean dynamic bending stiffness in flexion, extension, and lateral bending increased significantly with increasing load for both the intact FSU and TDR constructs (p<0.001). In flexion, with increasing compressive loading from 181N to 488N, the bending stiffness of the intact FSUs increased from 4.0N-m/° to 5.5N-m/°, compared to 2.1N-m/° to 3.6N-m/° after TDR implantation. At each compressive load, the intact FSU was significantly more stiff than the TDR (p<0.05). Conclusion Lumbar FSUs with implanted TDR were found to be less stiff, but also absorbed more energy during cyclic loading with an unconstrained pendulum system. Although the effects on clinical performance of motion preserving devices are not fully known, these results provide further insight into the biomechanical behavior of this device under approximated

  7. The Latest Lessons Learned from Retrieval Analyses of Ultra-High Molecular Weight Polyethylene, Metal-on-Metal, and Alternative Bearing Total Disc Replacements

    PubMed Central

    Kurtz, Steven M.; Toth, Jeffrey M.; Siskey, Ryan; Ciccarelli, Lauren; MacDonald, Dan; Isaza, Jorge; Lanman, Todd; Punt, Ilona; Steinbeck, Marla; Goffin, Jan; van Ooij, André

    2012-01-01

    Knowledge regarding the in vivo performance and periposthetic tissue response of cervical and lumbar total disc replacements (TDRs) continues to expand. This review addresses the following four main questions: 1) What are the latest lessons learned from polyethylene in large joints and how are they relevant to current TDRs? 2) What are the latest lessons learned regarding adverse local tissue reactions from metal-on-metal, CoCr bearings in large joints and how are they relevant to current TDRs? 3) What advancements have been made in understanding the in vivo performance of alternative biomaterials, such as stainless steel and polycarbonate urethane, for TDRs in the past five years? 4) How has retrieval analysis of all these various artificial disc bearing technologies advanced the state of the art in preclinical testing of TDRs? The study of explanted artificial discs and their associated tissues can help inform bearing selection as well as the design of future generations of disc arthroplasty. Analyzing retrieved artificial discs is also essential for validating preclinical test methods. PMID:22904606

  8. Long term preservation of motion with artificial cervical disc implants: A comparison between cervical disc replacement and rigid fusion with cage

    PubMed Central

    Cincu, Rafael; Lorente, Francisco de Asis; Gomez, Joaquin; Eiras, Jose; Agrawal, Amit

    2014-01-01

    Background: With the advancement of technologies there is more interest in the maintenance of the spine's biomechanical properties focusing on the preservation of the functional motion segment. In present article we describe our experience with 25 cases managed with artificial cervical discs with 28 Solis cage following cervical discectomy with a mean follow-up period of 7.5 year. Materials and Methods: All surgeries were performed by single surgeon from March 2004 to June 2005 with a follow-up till date. Patients with symptomatic single or multiple level diseases that had no prior cervical surgery were candidates for the study. Cohort demographics were comparable. Standardized clinical outcome measures and radiographic examinations were used at prescribed post-operative intervals to compare the treatment groups. Relief in radicular pain, cervical spine motion, and degenerative changes at follow-up were noted. Results: In a total 53 cases, the mean age in prosthesis group was 47 years (age range: 30-63 years) and mean age in cage group was 44 years (32-62 years). Mean hospital stay was 2.7 days in both the groups. At 4 weeks complete cervical movements could be achieved in 19 cases in artificial disc group. Maintenance of movement after 7.5 years was in 76% of these patients. Lordosis was maintained in all cases till date. There was no mortality or wound infection in our series. Conclusions: We conclude that artificial cervical disc could be an alternative to fixed spinal fusion as it represents the most physiological substitute of disc. However, there is need for further studies to support the use of artificial cervical disc prosthesis. PMID:25685218

  9. Submicron–sized UHMWPE wear particle analysis from revised SB Charité III total disc replacements

    PubMed Central

    Punt, Ilona M.; Baxter, Ryan M.; van Ooij, André; Willems, Paul C.; van Rhijn, Lodewijk W.; Kurtz, Steven M.; Steinbeck, Marla J.

    2011-01-01

    Submicron-sized particles are frequently observed in retrieved total hip and knee periprosthetic tissues and appear to be critical in the activation of the phagocytic inflammatory response. In this paper, the concentration, size and shape of ultra-high molecular weight polyethylene (UHMWPE) wear particles between 0.05–2.00 μm were determined after isolation from periprosthetic tissues from retrieved lumbar SB Charité III total disc replacements (TDR) using scanning electron microscopy (SEM). For comparison, UHMWPE wear particles were isolated from gamma-air sterilized total hip arthroplasty (THA) revision tissues. The mean concentration of UHMWPE particles in TDR tissues was 1.6 × 109/gram of tissue (range 1.3–2.0), which was significantly lower than the concentration of 2.3 × 109/gram of THA revision tissue (range 1.8–3.2) (p=0.03). The mean particle size (equivalent circular diameter, TDR: 0.46 μm, THA: 0.53 μm, p=0.60) and mean shape were comparable between TDR and THA (aspect ratio, TDR: 1.89, THA: 1.99, p=0.35; roundness, TDR: 0.58, THA: 0.56, p=0.35). However, the TDR particles in general were smaller and more round. Although no correlations were found between visible damage to the UHMWPE core and the concentration or shape of the UHMWPE particles, a positive correlation was found between increasing particle size and increasing rim penetration of the TDR core (p=0.04). The presence of UHMWPE particles of similar size and shape in TDR tissue albeit lower in concentration might explain why unlike THA, pain rather than osteolysis is the major reason for revision surgery. PMID:21621656

  10. The Mobi-C cervical disc for one-level and two-level cervical disc replacement: a review of the literature

    PubMed Central

    Alvin, Matthew D; Mroz, Thomas E

    2014-01-01

    Background Cervical disc arthroplasty (CDA) is a novel motion-preserving procedure that is an alternative to fusion. The Mobi-C disc prosthesis, one of many Food and Drug Administration (FDA)-approved devices for CDA, is the only FDA-approved prosthesis for two-level CDA. Hence, it may allow for improved outcomes compared with multilevel fusion procedures. Purpose To critically assess the available literature on CDA with the Mobi-C prosthesis, with a focus on two-level CDA. Methods All clinical articles involving the Mobi-C disc prosthesis for CDA through September 1, 2014 were identified on Medline. Any paper that presented Mobi-C CDA clinical results was included. Study design, sample size, length of follow-up, use of statistical analysis, quality of life outcome scores, conflict of interest, and complications were recorded. Results Fifteen studies were included that investigated Mobi-C CDA, only one of which was a level Ib randomized control trial. All studies included showed non-inferiority of one-level Mobi-C CDA to one-level anterior cervical discectomy and fusion (ACDF). Only one study analyzed outcomes of one-level versus two-level Mobi-C CDA, and only one study analyzed two-level Mobi-C CDA versus two-level ACDF. In comparison with other cervical disc prostheses, the Mobi-C prosthesis is associated with higher rates of heterotopic ossification (HO). Studies with conflicts of interest reported lower rates of HO. Adjacent segment degeneration or disease, along with other complications, were not assessed in most studies. Conclusion One-level Mobi-C CDA is non-inferior, but not superior, to one-level ACDF for patients with cervical degenerative disc disease. The Mobi-C CDA procedure is associated with high rates of HO. Two-level Mobi-C CDA may be superior to two-level ACDF. However, insufficient evidence exists, thereby mandating a need for unbiased, well-designed prospective studies with well-defined outcomes in the future. PMID:25473319

  11. Analysis of post-operative pain patterns following total lumbar disc replacement: results from fluoroscopically guided spine infiltrations

    PubMed Central

    Korge, Andreas; Grochulla, Frank; Mehren, Christoph

    2007-01-01

    Although a variety of biomechanical laboratory investigations and radiological studies have highlighted the potential problems associated with total lumbar disc replacement (TDR), no previous study has performed a systematic clinical failure analysis. The aim of this study was to identify the post-operative pain sources, establish the incidence of post-operative pain patterns and investigate the effect on post-operative outcome with the help of fluoroscopically guided spine infiltrations in patients from an ongoing prospective study with ProDisc II. Patients who reported unsatisfactory results at any of the FU-examinations received fluoroscopically guided spine infiltrations as part of a semi-invasive diagnostic and conservative treatment program. Pain sources were identified in patients with reproducible (≥2×) significant (50–75%) or highly significant (75–100%) pain relief. Results were correlated with outcome parameters visual analogue scale (VAS), Oswestry disability index (ODI) and the subjective patient satisfaction rate. From a total of 175 operated patients with a mean follow-up (FU) of 29.3 months (range 12.2–74.9 months), n = 342 infiltrations were performed in n = 58 patients (33.1%) overall. Facet joint pain, predominantly at the index level (86.4%), was identified in n = 22 patients (12.6%). The sacroiliac joint was a similarly frequent cause of post-operative pain (n = 21, 12.0%). Pain from both structures influenced all outcome parameters negatively (P < 0.05). Patients with an early onset of pain (≤6 months) were 2–5× higher at risk of developing persisting complaints and unsatisfactory outcome at later FU-stages in comparison to the entire study cohort (P < 0.05). The level of TDR significantly influenced post-operative outcome. Best results were achieved for the TDRs above the lumbosacral junction at L4/5 (incidence of posterior joint pain 14.8%). Inferior outcome and a significantly higher incidence of posterior joint

  12. Analysis of post-operative pain patterns following total lumbar disc replacement: results from fluoroscopically guided spine infiltrations.

    PubMed

    Siepe, Christoph J; Korge, Andreas; Grochulla, Frank; Mehren, Christoph; Mayer, H Michael

    2008-01-01

    Although a variety of biomechanical laboratory investigations and radiological studies have highlighted the potential problems associated with total lumbar disc replacement (TDR), no previous study has performed a systematic clinical failure analysis. The aim of this study was to identify the post-operative pain sources, establish the incidence of post-operative pain patterns and investigate the effect on post-operative outcome with the help of fluoroscopically guided spine infiltrations in patients from an ongoing prospective study with ProDisc II. Patients who reported unsatisfactory results at any of the FU-examinations received fluoroscopically guided spine infiltrations as part of a semi-invasive diagnostic and conservative treatment program. Pain sources were identified in patients with reproducible (> or =2x) significant (50-75%) or highly significant (75-100%) pain relief. Results were correlated with outcome parameters visual analogue scale (VAS), Oswestry disability index (ODI) and the subjective patient satisfaction rate. From a total of 175 operated patients with a mean follow-up (FU) of 29.3 months (range 12.2-74.9 months), n = 342 infiltrations were performed in n = 58 patients (33.1%) overall. Facet joint pain, predominantly at the index level (86.4%), was identified in n = 22 patients (12.6%). The sacroiliac joint was a similarly frequent cause of post-operative pain (n = 21, 12.0%). Pain from both structures influenced all outcome parameters negatively (P < 0.05). Patients with an early onset of pain (< or =6 months) were 2-5x higher at risk of developing persisting complaints and unsatisfactory outcome at later FU-stages in comparison to the entire study cohort (P < 0.05). The level of TDR significantly influenced post-operative outcome. Best results were achieved for the TDRs above the lumbosacral junction at L4/5 (incidence of posterior joint pain 14.8%). Inferior outcome and a significantly higher incidence of posterior joint pain were observed

  13. Total disc replacement compared to lumbar fusion: a randomised controlled trial with 2-year follow-up

    PubMed Central

    Tullberg, Tycho; Branth, Björn; Olerud, Claes; Tropp, Hans

    2009-01-01

    The study design includes a prospective, randomised controlled study comparing total disc replacement (TDR) with posterior fusion. The main objective of this study is to compare TDR with lumbar spinal fusion, in terms of clinical outcome, in patients referred to a spine clinic for surgical evaluation. Fusion is effective for treating chronic low back pain (LBP), but has drawbacks, such as stiffness and possibly adjacent level degradation. Motion-preserving options have emerged, of which TDR is frequently used because of these drawbacks. How the results of TDR compare to fusion, however, is uncertain. One hundred and fifty-two patients with a mean age of 40 years (21–55) were included: 90 were women, and 80 underwent TDR. The patients had not responded to a conservative treatment programme and suffered from predominantly LBP, with varying degrees of leg pain. Diagnosis was based on clinical examination, radiographs, MRI, and in unclear cases, diagnostic injections. Outcome measures were global assessment (GA), VAS for back and leg pain, Oswestry Disability Index, SF36 and EQ5D at 1 and 2 years. Follow-up rate was 100%, at both 1 and 2 years. All outcome variables improved in both groups between preoperative and follow-up assessment. The primary outcome measure, GA, revealed that 30% in the TDR group and 15% in the fusion group were totally pain-free at 2 years (P = 0.031). TDR patients had reached maximum recovery in virtually all variables at 1 year, with significant differences compared to the fusion group. The fusion patients continued to improve and at 2 years had results similar to TDR patients apart from numbers of pain-free. Complications and reoperations were similar in both groups, but pedicle screw removal as additive surgery, was frequent in the fusion group. One year after surgery, TDR was superior to spinal fusion in clinical outcome, but this difference had diminished by 2 years, apart from (VAS for back pain and) numbers of pain-free. The

  14. Failure analysis of C-5 after total disc replacement with ProDisc-C at 1 and 2 levels and in combination with a fusion cage: finite-element and biomechanical models.

    PubMed

    Completo, António; Nascimento, Abel; Ramos, António; Simões, José

    2015-06-01

    OBJECT The purpose of this study was to evaluate the failure risk of cervical vertebrae after total disc replacement with a keel-design prosthesis (ProDisc-C), taking into consideration the effects of vertebral body height, multilevel replacement, and the association with an adjacent fusion cage. Although promising clinical results have been reported for the ProDisc-C, some clinical studies have reported vertebral body-splitting fractures at single- and multilevel arthroplasty sites. This implant has central keels to provide solid initial stability, and some authors associate the potential risk of vertebral body failure with the keel design, especially in patients with small vertebral body height or when the implant is used at multiple levels. METHODS The study was performed using a specimen-specific C4-6 cervical-segment finite-element model to assess the compressive strains on the C-5 vertebral body for each cervical segment configuration, and synthetic polyurethane models to experimentally predict the compressive load at failure for 3 vertebral body heights. RESULTS The use of a keeled ProDisc-C prosthesis at multiple levels or in combination with a fusion cage increases by a factor of 2-3 the compressive strains at the C-5 vertebral body relative to single-level arthroplasty. All implanted segment configurations tested demonstrated a continuum of the load at failure and the vertebral body height, but no significant differences were found between the 3 vertebral body heights in each segment configuration. CONCLUSIONS The use of a keeled ProDisc-C prosthesis at 2 adjacent levels or combined with a fusion cage presented the lowest load-at-failure values, 2 times higher on average than the ones occurring during physiological tasks. This fact indicates an identical and limited risk of vertebral body failure for these 2 segment configurations, whereas vertebral body height appears to slightly affect this risk. However, for some tasks that place higher physical

  15. A case of cervical metastases in a patient with preexisting cervical disc replacement and fusion after 2-year symptom-free interval: when do we need interdisciplinary diagnostics?

    PubMed Central

    Melloh, Markus; Barz, Thomas

    2012-01-01

    Recurrent cervical symptoms frequently occur after cervical disc replacement and fusion. To date, no algorithm for the diagnostic assessment of these symptoms has been established. We present a case report and review of the literature to illustrate the need for interdisciplinary diagnostics in recurrent cervicobrachialgia without pathological cervical imaging. The hospital chart, medical history, physical examination, and imaging of a single patient were reviewed. A 53-year-old man with preexisting cervical disc replacement and fusion presented with a new episode of cervicobrachialgia after a 2-year symptom-free interval. Cervical magnetic resonance imaging (MRI) showed no pathological findings. Six months later the patient reported increasing symptoms including numbness and weakness of the right arm. Repeated cervical MRI and thoracic computed tomography revealed cervical metastases with intraspinal tumor growth and an underlying extensive small cell bronchial carcinoma. In recurrent cervicobrachialgia, without pathological cervical imaging, interdisciplinary diagnostics are needed. Basic diagnostic tests may assist to exclude severe non-vertebrogenic pathologies. PMID:23526906

  16. Subsequent surgery rates after cervical total disc replacement using a Mobi-C Cervical Disc Prosthesis versus anterior cervical discectomy and fusion: a prospective randomized clinical trial with 5-year follow-up.

    PubMed

    Jackson, Robert J; Davis, Reginald J; Hoffman, Gregory A; Bae, Hyun W; Hisey, Michael S; Kim, Kee D; Gaede, Steven E; Nunley, Pierce Dalton

    2016-05-01

    OBJECTIVE Cervical total disc replacement (TDR) has been shown in a number of prospective clinical studies to be a viable treatment alternative to anterior cervical discectomy and fusion (ACDF) for the treatment of symptomatic degenerative disc disease. In addition to preserving motion, evidence suggests that cervical TDR may result in a lower incidence of subsequent surgical intervention than treatment with fusion. The goal of this study was to evaluate subsequent surgery rates up to 5 years in patients treated with TDR or ACDF at 1 or 2 contiguous levels between C-3 and C-7. METHODS This was a prospective, multicenter, randomized, unblinded clinical trial. Patients with symptomatic degenerative disc disease were enrolled to receive 1- or 2-level treatment with either TDR as the investigational device or ACDF as the control treatment. There were 260 patients in the 1-level study (179 TDR and 81 ACDF patients) and 339 patients in the 2-level study (234 TDR and 105 ACDF patients). RESULTS At 5 years, the occurrence of subsequent surgical intervention was significantly higher among ACDF patients for 1-level (TDR, 4.5% [8/179]; ACDF, 17.3% [14/81]; p = 0.0012) and 2-level (TDR, 7.3% [17/234]; ACDF, 21.0% [22/105], p = 0.0007) treatment. The TDR group demonstrated significantly fewer index- and adjacent-level subsequent surgeries in both the 1- and 2-level cohorts. CONCLUSIONS Five-year results showed treatment with cervical TDR to result in a significantly lower rate of subsequent surgical intervention than treatment with ACDF for both 1 and 2 levels of treatment. Clinical trial registration no.: NCT00389597 ( clinicaltrials.gov ). PMID:26799118

  17. Internal carotid artery dissection after anterior cervical disc replacement: first case report and literature review of vascular complications of the approach.

    PubMed

    Loret, Jean-Edouard; Francois, Patrick; Papagiannaki, Chrysanthi; Cottier, Jean-Philippe; Terrier, Louis-Marie; Zemmoura, Ilyess

    2013-07-01

    We report the case of a 41-year-old woman who underwent cervical total disc replacement at C4C5 and C5C6 levels and fusion at C6C7 level through an anterior right-side approach. After anesthesia recovery, the patient presented left hemiparesia and facial palsy due to large right hemispheric stroke. Diffusion-weighted magnetic resonance imaging was performed as soon as the patient developed neurologic symptoms of stroke and revealed a right internal carotid artery dissection. Digital substraction angiography, endovascular stenting, angioplasty and thrombectomy were performed. Six months after treatment, clinical examination showed mild left-arm spasticity. To the best of our knowledge, only two cases of internal carotid artery stroke without dissection or thrombosis are reported. In conclusion, although vascular complications are rare after anterior cervical spine procedure, internal carotid artery dissection can occur. Suspected risk factors are prolonged retraction of the carotid artery and neck extension. PMID:23728441

  18. Postero-Lateral Disc Prosthesis Combined With a Unilateral Facet Replacement Device Maintains Quantity and Quality of Motion at a Single Lumbar Level

    PubMed Central

    Nayak, Aniruddh N.; Doarn, Michael C.; Gaskins, Roger B.; James, Chris R.; Cabezas, Andres F.; Castellvi, Antonio E.

    2014-01-01

    Background Mechanically replacing one or more pain generating articulations in the functional spinal unit (FSU) may be a motion preservation alternative to arthrodesis at the affected level. Baseline biomechanical data elucidating the quantity and quality of motion in such arthroplasty constructs is non-existent. Purpose The purpose of the study was to quantify the motion-preserving effect of a posterior total disc replacement (PDR) combined with a unilateral facet replacement (FR) system at a single lumbar level (L4-L5). We hypothesized that reinforcement of the FSU with unilateral FR to replace the resected, native facet joint following PDR implantation would restore quality and quantity of motion and additionally not change biomechanics at the adjacent levels. Study Design In-vitro study using human cadaveric lumbar spines. Methods Six (n = 6) cadaveric lumbar spines (L1-S1) were evaluated using a pure-moment stability testing protocol (±7.5 Nm) in flexion-extension (F/E), lateral bending (LB) and axial rotation (AR). Each specimen was tested in: (1) intact; (2) unilateral FR; and (3) unilateral FR + PDR conditions. Index and adjacent level ROM (using hybrid protocol) were determined opto-electronically. Interpedicular travel (IPT) and instantaneous center of rotation (ICR) at the index level were radiographically determined for each condition. ROM, ICR, and IPT measurements were compared (repeated measures ANOVA) between the three conditions. Results Compared to the intact spine, no significant changes in F/E, LB or AR ROM were identified as a result of unilateral FR or unilateral FR + PDR. No significant changes in adjacent L3-L4 or L5-S1 ROM were identified in any loading mode. No significant differences in IPT were identified between the three test conditions in F/E, LB or AR at the L4-L5 level. The ICRs qualitatively were similar for the intact and unilateral FR conditions and appeared to follow placement (along the anterior-posterior (AP) direction) of

  19. Prospective, Randomized Comparison of One-level Mobi-C Cervical Total Disc Replacement vs. Anterior Cervical Discectomy and Fusion: Results at 5-year Follow-up

    PubMed Central

    Zigler, Jack E.; Jackson, Robert; Nunley, Pierce D.; Bae, Hyun W.; Kim, Kee D.; Ohnmeiss, Donna D.

    2016-01-01

    Introduction There is increasing interest in the role of cervical total disc replacement (TDR) as an alternative to anterior cervical discectomy and fusion (ACDF). Multiple prospective randomized studies with minimum 2 year follow-up have shown TDR to be at least as safe and effective as ACDF in treating symptomatic degenerative disc disease at a single level. The purpose of this study was to compare outcomes of cervical TDR using the Mobi-C® with ACDF at 5-year follow-up. Methods This prospective, randomized, controlled trial was conducted as a Food and Drug Administration regulated Investigational Device Exemption trial across 23 centers with 245 patients randomized (2:1) to receive TDR with Mobi-C® Cervical Disc Prosthesis or ACDF with anterior plate and allograft. Outcome assessments included a composite overall success score, Neck Disability Index (NDI), visual analog scales (VAS) assessing neck and arm pain, Short Form-12 (SF-12) health survey, patient satisfaction, major complications, subsequent surgery, segmental range of motion, and adjacent segment degeneration. Results The 60-month follow-up rate was 85.5% for the TDR group and 78.9% for the ACDF group. The composite overall success was 61.9% with TDR vs. 52.2% with ACDF, demonstrating statistical non-inferiority. Improvements in NDI, VAS neck and arm pain, and SF-12 scores were similar between groups and were maintained from earlier follow-up through 60 months. There was no significant difference between TDR and ACDF in adverse events or major complications. Range of motion was maintained with TDR through 60 months. Device-related subsequent surgeries (TDR: 3.0%, ACDF: 11.1%, p<0.02) and adjacent segment degeneration at the superior level (TDR: 37.1%, ACDF: 54.7%, p<0.03) were significantly lower for TDR patients. Conclusions Five-year results demonstrate the safety and efficacy of TDR with the Mobi-C as a viable alternative to ACDF with the potential advantage of lower rates of reoperation and

  20. Influence of the loading frequency on the wear rate of a polyethylene-on-metal lumbar intervertebral disc replacement.

    PubMed

    Kettler, Annette; Bushelow, Michael; Wilke, Hans-Joachim

    2012-06-01

    Pre-clinical wear testing of intervertebral disc prostheses is commonly carried out according to ISO 18192-1. Ten million multiaxial loading cycles are applied at a frequency of 1 Hz. At this frequency, testing takes about 4 months. Testing at higher frequencies would therefore be desirable. ISO 18192-1 also offers testing at 2 Hz; however, it says the impact on the implant material behaviour as well as on the accuracy of the test machine shall be investigated by the user. Since such data are not available so far, the aim of this study was to carry out comparative wear tests at 1 and 2 Hz. Seven Prodisc-L lumbar disc prostheses were tested. After a pre-soak period, the implants were placed in specimen cups filled with calf serum, mounted to a Spine Wear Simulator and loaded according to ISO 18192-1. Testing was carried out at a temperature of 37 ± 2 °C. Four million loading cycles were applied at 1 Hz and eight million at 2 Hz in an alternating sequence. Each time after 12 days of testing the implants were removed to measure the weight and the height of the polyethylene cores. Then, the test serum was exchanged and the implants were remounted to the testing machine. The mean wear rate was 5.6 ± 2.3 mg per million cycles at 1 Hz and 7.7 ± 1.6 mg per million cycles at 2 Hz during the first six million loading cycles (p < 0.05) and 2.0 ± 0.6 and 4.1 ± 0.7 mg per million cycles during the second six million cycles (p < 0.05). Similarly, the mean heightloss was also smaller at 1 Hz than at 2 Hz (p < 0.05) with -0.02 ± 0.02 mm versus -0.04 ± 0.02 mm per million cycles during the first half of testing and -0.01 ± 0.01 versus -0.02 ± 0.01 mm per million cycles during the second half. The accuracy of the test machine was within the limits described by ISO 18192-1 at both frequencies. The results showed that the wear rate was higher at the beginning than at the end of testing. Also, the results indicated that testing at 2 Hz increases the wear rate compared with 1

  1. Comparison of single-level L4–L5 versus L5–S1 lumbar disc replacement: results and prognostic factors

    PubMed Central

    Bundy, Albert; Costantini, Sandro; Nena, Ugo; Finocchiaro, Francesco; Monterumici, Daniele A. Fabris

    2009-01-01

    The aim of our prospective non-randomized clinical study was to analyze operative data, short-term results, safety, efficacy, complications, and prognostic factors for single-level total lumbar disc replacement (TLDR), and to compare results between different levels (L4–L5 vs. L5–S1). Thirty-six patients with single-level L4–L5 or L5–S1 TLDR, with 1-year minimum follow-up (FU), had complete clinical [SF36, visual analog scale (VAS), Oswestry Disability Index (ODI)] and radiological data, and were included in our study. Mean FU was 38.67 ± 17.34 months. Replaced level was L4–L5 in 12 (33.3%) cases, and L5–S1 in 24 cases (66.7%). Mean age at diagnosis was 41.17 ± 7.14 years. 24 (66.7%) were females and 12 (33.3%) were males. Statistical analyses were assessed using t tests or Mann–Whitney test for continuous variables and Chi-square test or Fisher’s exact test analyses for categorical variables. Univariate linear regression and binary logistic regression analyses were utilized to evaluate the relationship between surgical outcomes and covariates (gender, age, etiology, treated level, pre-operative SF36, ODI, and VAS). Mean operative time was 147.03 ± 30.03 min. Mean hospital stay was 9.69 ± 5.39 days, and mean return to ambulation was 4.31 ± 1.17 days. At 1-year FU, patients revealed a statistical significant improvement in VAS pain (P = 0.000), ODI lumbar function (P = 0.000), and SF36 general health status (P = 0.000). Single-level TLDR is a good alternative to fusion for chronic discogenic low back pain refractory to conservative measures. Our study confirmed satisfactory clinical results for monosegmental L4–L5 and L5–S1 disc prosthesis, with no difference between the two different levels for SF36 (P = 0.217), ODI (P = 0.527), and VAS (P = 0.269). However, replacement of the L4–L5 disc is affected by an increased risk of complication (P = 0.000). There were no prognostic factors for intraoperative blood

  2. The impact of implantation technique on frontal and sagittal alignment in total lumbar disc replacement: a comparison of anterior versus oblique implantation

    PubMed Central

    Obertacke, U.; Nothwang, J.; Ulrich, C.; Nowicki, J.; Reichel, H.; Cakir, B.

    2010-01-01

    The concept of total lumbar disc replacement (TDR) is gaining acceptance due to good clinical short-term outcome. Standard implantation is strict anterior, which poses especially above the segment L5/S1 sometimes difficulties due to the vessel configuration. Therefore, oblique implantable TDR have been invented. In oblique implantation the anterior longitudinal ligament (ALL) is only partially resected, with additional partial resection of lateral annulus fibers. This could have an impact on biomechanical properties, which has not been evaluated until now. We therefore compared the standing ap and lateral X-rays pre- and postoperative after anterior and oblique implantation of TDR in segment L4/5. Significant differences between the groups were not found. In both the anterior and oblique group, segmental lordosis showed a significant increase, whereas total lordosis as well as ap balance were unchanged. The absolute segmental lordosis increase was nearly double in the anterior group. In conclusion, both anterior and oblique implanted TDR significantly increase segmental lordosis while retaining total lordosis and ap balance. The segmental increase is lower in the oblique implanted group which is probably due to the remaining ALL. Further studies should evaluate whether this finding has any implication for the long-term outcome. PMID:20490873

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

    PubMed

    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. PMID:26758702

  4. Are periprosthetic tissue reactions observed after revision of total disc replacement comparable to the reactions observed after total hip or knee revision surgery?

    PubMed Central

    Punt, Ilona M.; Austen, Shennah; Cleutjens, Jack P.M.; Kurtz, Steven M.; ten Broeke, René H.M.; van Rhijn, Lodewijk W.; Willems, Paul C.; van Ooij, André

    2011-01-01

    Study design Comparative study. Objective To compare periprosthetic tissue reactions observed after total disc replacement (TDR), total hip arthroplasty (THA) and total knee arthroplasty (TKA) revision surgery. Summary of background data Prosthetic wear debris leading to particle disease, followed by osteolysis, is often observed after THA and TKA. Although the presence of polyethylene (PE) particles and periprosthetic inflammation after TDR has been proven recently, osteolysis is rarely observed. The clinical relevance of PE wear debris in the spine remains poorly understood. Methods Number, size and shape of PE particles, as well as quantity and type of inflammatory cells in periprosthetic tissue retrieved during Charité TDR (n=22), THA (n=10) and TKA (n=4) revision surgery were compared. Tissue samples were stained with hematoxylin/eosin and examined by using light microscopy with bright field and polarized light. Results After THA, large numbers of PE particles <6 µm were observed, which were mainly phagocytosed by macrophages. The TKA group had a broad size range with many larger PE particles and more giant cells. In TDR, the size range was similar to that observed in TKA. However, the smallest particles were the most prevalent with 75% of the particles being <6 µm, as seen in revision THA. In TDR, both macrophages and giant cells were present with a higher number of macrophages. Conclusions Both small and large PE particles are present after TDR revision surgery compatible with both THA and TKA wear patterns. The similarities between periprosthetic tissue reactions in the different groups may give more insight in the clinical relevance of PE particles and inflammatory cells in the lumbar spine. The current findings may help to improve TDR design as applied from technologies previously developed in THA and TKA with the goal of a longer survival of TDR. PMID:21336235

  5. Cervical arthroplasty using ProDisc-C case report.

    PubMed

    Nica, D A; Copaciu, R

    2013-03-15

    Cervical disc replacement is an emerging motion-preserving technology in the surgical treatment of the cervical degenerative disc disorders used as an alternative to the classic interbody fusion. We present a case report of a patient diagnosed with C6-7 right disc herniation who underwent anterior discectomy and received a total disc replacement using ProDisc C artificial disc prosthesis. PMID:23599830

  6. Cross-shear implementation in sliding-distance-coupled finite element analysis of wear in metal-on-polyethylene total joint arthroplasty: intervertebral total disc replacement as an illustrative application.

    PubMed

    Goreham-Voss, Curtis M; Hyde, Philip J; Hall, Richard M; Fisher, John; Brown, Thomas D

    2010-06-18

    Computational simulations of wear of orthopaedic total joint replacement implants have proven to valuably complement laboratory physical simulators, for pre-clinical estimation of abrasive/adhesive wear propensity. This class of numerical formulations has primarily involved implementation of the Archard/Lancaster relationship, with local wear computed as the product of (finite element) contact stress, sliding speed, and a bearing-couple-dependent wear factor. The present study introduces an augmentation, whereby the influence of interface cross-shearing motion transverse to the prevailing molecular orientation of the polyethylene articular surface is taken into account in assigning the instantaneous local wear factor. The formulation augment is implemented within a widely utilized commercial finite element software environment (ABAQUS). Using a contemporary metal-on-polyethylene total disc replacement (ProDisc-L) as an illustrative implant, physically validated computational results are presented to document the role of cross-shearing effects in alternative laboratory consensus testing protocols. Going forward, this formulation permits systematically accounting for cross-shear effects in parametric computational wear studies of metal-on-polyethylene joint replacements, heretofore a substantial limitation of such analyses. PMID:20399432

  7. Cross-Shear Implementation in Sliding-Distance-Coupled Finite Element Analysis of Wear in Metal-on-Polyethylene Total Joint Arthroplasty: Intervertebral Total Disc Replacement as an Illustrative Application

    PubMed Central

    Goreham-Voss, Curtis M.; Hyde, Philip J.; Hall, Richard M.; Fisher, John; Brown, Thomas D.

    2010-01-01

    Computational simulations of wear of orthopaedic total joint replacement implants have proven to valuably complement laboratory physical simulators, for pre-clinical estimation of abrasive/adhesive wear propensity. This class of numerical formulations has primarily involved implementation of the Archard/Lancaster relationship, with local wear computed as the product of (finite element) contact stress, sliding speed, and a bearing-couple-dependent wear factor. The present study introduces an augmentation, whereby the influence of interface cross-shearing motion transverse to the prevailing molecular orientation of the polyethylene articular surface is taken into account in assigning the instantaneous local wear factor. The formulation augment is implemented within a widely-utilized commercial finite element software environment (ABAQUS). Using a contemporary metal-on-polyethylene total disc replacement (ProDisc-L) as an illustrative implant, physically validated computational results are presented to document the role of cross-shearing effects in alternative laboratory consensus testing protocols. Going forward, this formulation permits systematically accounting for cross-shear effects in parametric computational wear studies of metal-on-polyethylene joint replacements, heretofore a substantial limitation of such analyses. PMID:20399432

  8. Seven PC Purchasing Pitfalls.

    ERIC Educational Resources Information Center

    Wodarz, Nan

    1997-01-01

    Explores how to avoid common pitfalls when schools purchase computer equipment. Purchasing tips are provided in the areas of choosing multiple platforms, buying the cheapest model available, choosing a proprietary design, falling for untested technology, purchasing systems that are not upgradable, ignoring extended warranties, and failing to plan…

  9. PACS pitfalls and bottlenecks

    NASA Astrophysics Data System (ADS)

    Huang, H. K.; Lou, Shyhliang A.; Wong, Albert W. K.

    1997-05-01

    PACS pitfalls are mostly created from human error, whereas bottlenecks are due to imperfect design in either the PACS or image acquisition devices. These drawbacks can only be realized through accumulated clinical experience. Pitfalls due to human error are often initiated at imaging acquisition devices and at workstations. Three major errors at the acquisition devices are entering wrong input parameters, stopping an image transmission process improperly, and incorrect patient positioning. The error occurring most often at the workstation happens when the user enters too many key strokes or clicks the mouse too often before the workstation can respond. Other pitfalls at the workstation unrelated to human error are missing location markers in a CT or MR scout view, images displayed with unsuitable look-up-tables, and white boarders in CR images due to x-ray collimation. Pitfalls created due to human intervention can be minimized by a better quality assurance program and periodic in-service training, and by interfacing image acquisition devices to the HIS/RIS. Bottlenecks affecting the PACS operation include network contention; CR, CT, and MR images stacked up at acquisition devices; slow response from workstations; and long delays for image retrieval from the long term archive. Bottlenecks can be alleviated by improving the system architecture, re- configuring the networks, and streamlining operational procedures through a gradual understanding of the clinical environment. We have identified most of the pitfalls and bottlenecks discussed above in our hospital-integrated PACS based on the past two years of clinical experience. This paper categorizes some of these problems, illustrates their effect on PACS operations, and suggests methods for circumventing them.

  10. Double-level cervical total disc replacement for adjacent segment disease: is it a useful treatment? Description of late onset heterotopic ossification and review of the literature.

    PubMed

    Barbagallo, G M V; Certo, F; Visocchi, M; Sciacca, G; Albanese, V

    2014-01-01

    We report a rare case of double-level adjacent segment disease (ASD), occurring ten years later an anterior cervical discectomy (ACD) without fusion, treated by cervical arthroplasty, highlighting the outcome at long-term follow-up and focusing on heterotopic ossification. In 1995 a 25-year-old man satisfactorily underwent ACD at C4/C5. At that time MRI also showed signs of degenerative disc disease (DDD) at C3/C4 and C5/C6. Ten years later, a new MRI scan showed a large C3/C4 and a smaller C5/C6 soft disc hernia together with spondylotic changes at the level above and below the site of the first surgery. At C4/C5 imaging revealed a kyphotic stable "pseudoarthrosis" with anterior bridging osteophyte. The patient underwent double-level arthroplasty with ProDisc-C. Clinical and radiological outcome was satisfactory. 3 and 5 years after surgery, X-rays and CT scan documented the progressive development of heterotopic ossification, with gradual reduction of range of motion. A late onset heterotopic ossification can neutralize the theoretical advantages of cervical arthroplasty, which should be considered an effective surgical option only in selected cases. ACDF and restoration of normal lordosis can be a viable alternative in cervical revision surgery, as motion preservation can not be always mantained for a long time. PMID:24825036

  11. Cost comparison of patients with 3-level artificial total lumbar disc replacements versus 360° fusion at 3 contiguous lumbar vertebral levels: an analysis of compassionate use at 1 site of the US investigational device exemption clinical trial

    PubMed Central

    Buttacavoli, Frank A.; Delamarter, Rick B.; Kanim, Linda E.A.

    2010-01-01

    Background We sought to evaluate the difference between hospital service costs of 2 treatment options for patients diagnosed with 3-level degenerative disc disease (DDD) in the lumbar spine. In this retrospective analysis, itemized billing records of hospital stay for patients with 3-level DDD treated with artificial disc replacement (ADR) were compared with those treated with circumferential fusion (standard of care). Methods Sequential 3-level DDD patients treated with either ADR (ProDisc-L; Synthes, West Chester, Pennsylvania) or circumferential fusion during the period from January 2004 to October 2005 were included. Surgeries were performed at the same hospital for all patients. The ADR-treated patients were participating in the investigational device exemption clinical trial as part of the compassionate-use arm. Patients treated with fusion at the same institution during this same time interval were evaluated. Itemized billing records were collected at least 1 year after the index surgery. Costs according to hospital service categories were compared between ADR-treated and fusion-treated patients by use of analysis of variance and multivariate statistical techniques. Results There were 43 consecutive patients treated for 3-level DDD between January 2004 and October 2005. Of these, 21 underwent 3-level ADR and 22 had a 3-level fusion procedure. There was a mean of 3 fewer hospital days for patients treated with ADR (4.77 ± 1.11 days) than for those treated with fusion (8.00 ± 1.82 days) (P < .0001). The cost of hospital services for ADR-treated patients was 49% less excluding instrumentation costs and 54% less when accounting for instrumentation. The pattern of cost was similar when workers’ compensation patients were analyzed separately. Conclusions ADR-treated 3-level patients benefited from significantly lower costs from their in-hospital stay compared with those treated by fusion. Hospital service costs were 49% (54% when instrumentation was included

  12. Pitfalls in developmental diagnosis.

    PubMed Central

    Illingworth, R S

    1987-01-01

    I have never seen a paper or chapter of a book devoted to pitfalls and mistakes in developmental diagnosis. This paper is designed to try to fill the gap. It concerns the avoidance of mistakes in developmental diagnosis and is based entirely on mistakes that I have made myself and now learned to try to avoid and on mistakes that I have seen, most of them repeatedly. I have made no mention of mistakes that could theoretically be made but that I have not personally seen. I believe that most assessment errors are due to overconfidence and to the view that developmental diagnosis is easy. Many other mistakes are due to reliance on purely objective tests with consequent omission of a detailed history and physical examination, so that factors that profoundly affect development but are not directly related to the child's mental endowment are not weighed up before an opinion is reached. PMID:2444167

  13. Use of adipose stem cells and polylactide discs for tissue engineering of the temporomandibular joint disc

    PubMed Central

    Mäenpää, Katja; Ellä, Ville; Mauno, Jari; Kellomäki, Minna; Suuronen, Riitta; Ylikomi, Timo; Miettinen, Susanna

    2010-01-01

    There is currently no suitable replacement for damaged temporomandibular joint (TMJ) discs after discectomy. In the present study, we fabricated bilayer biodegradable polylactide (PLA) discs comprising a non-woven mat of poly(L/D)lactide (P(L/D)LA) 96/4 and a P(L/DL)LA 70/30 membrane plate. The PLA disc was examined in combination with adipose stem cells (ASCs) for tissue engineering of the fibrocartilaginous TMJ disc in vitro. ASCs were cultured in parallel in control and chondrogenic medium for a maximum of six weeks. Relative expression of the genes, aggrecan, type I collagen and type II collagen present in the TMJ disc extracellular matrix increased in the ASC-seeded PLA discs in the chondrogenic medium. The hypertrophic marker, type X collagen, was moderately induced. Alcian blue staining showed accumulation of sulphated glycosaminoglycans. ASC differentiation in the PLA discs was close to that observed in pellet cultures. Comparison of the mRNA levels revealed that the degree of ASC differentiation was lower than that in TMJ disc-derived cells and tissue. The pellet format supported the phenotype of the TMJ disc-derived cells under chondrogenic conditions and also enhanced their hyalinization potential, which is considered part of the TMJ disc degeneration process. Accordingly, the combination of ASCs and PLA discs has potential for the development of a tissue-engineered TMJ disc replacement. PMID:19474082

  14. [Cervical disc herniation].

    PubMed

    Schnake, K J; Hoffmann, C-H; Kandziora, F

    2012-12-01

    The cervical disc herniation is characterized by prolapsed nucleus pulposus material through the annulus into the spinal canal. The local mechanical or chemical irritation of neural structures typically leads to symptoms of radiculopathy, cervicocephalgia or myelopathy. Pronounced sensorimotor deficits or intractable pain constitute surgical treatment. In all other cases conservative treatment is indicated, including pain medication, active and passive physiotherapy, and local injections, respectively. Anterior cervical discectomy and interbody fusion (ACDF) is still the surgical treatment of choice. Predominantly, cages with or without plates are in use to obtain solid fusion. The implantation of a total disc replacement is a viable alternative, if no contraindications exist. Other surgical techniques may be performed in proper selected cases. The overall clinical and radiological results of both surgical and conservative treatment are good. PMID:23296562

  15. Artificial Cervical Disc Replacement Improves Mobility

    MedlinePlus Videos and Cool Tools

    ... screen and open the door to informed medical care. OR Live, the vision of improving health. Hi, ... screen and open the door to informed medical care. “OR Live,” the vision of improving health. 11

  16. Pitfalls in penetrating trauma.

    PubMed

    van Vugt, A B

    2003-08-01

    In Western Europe the most frequent cause of multiple injuries is blunt trauma. Only few of us have experience with penetrating trauma, without exception far less than in the USA or South-Africa. In Rotterdam, the Erasmus Medical Centre is a level I trauma centre, situated directly in the town centre. All penetrating traumas are directly presented to our emergency department by a well organized ambulance service supported by a mobile medical team if necessary. The delay with scoop and run principles is very short for these cases, resulting in severely injured reaching the hospital alive in increasing frequency. Although the basic principles of trauma care according to the guidelines of the Advanced Trauma Life Support (ATLS) (1-2) are the same for blunt and penetrating trauma with regard to priorities, diagnostics and primary therapy, there are some pitfalls in the strategy of management in penetrating trauma one should be aware of. Simple algorithms can be helpful, especially in case of limited experience (3). In case of life-saving procedures, the principles of Damage Control Surgery (DCS) must be followed (4-5). This approach is somewhat different from "traditional" surgical treatment. In the Ist phase prompt interventions by emergency thoracotomy and laparotomy are carried out, with only two goals to achieve: surgical control of haemorrhage and contamination. After temporary life-saving procedures, the 2nd phase is characterized by intensive care treatment, dealing with hypothermia, metabolic acidosis and clotting disturbances. Finally in the 3rd phase, within 6-24 hours, definitive surgical care takes place. In this overview, penetrating injuries of neck, thorax, abdomen and extremities will be outlined. Penetrating cranial injuries, as a neurosurgical emergency with poor prognosis, are not discussed. History and physical examination remain the corner stones of good medical praxis. In a work-up according to ATLS principles airway, breathing and circulation

  17. Janus discs.

    PubMed

    Walther, Andreas; André, Xavier; Drechsler, Markus; Abetz, Volker; Müller, Axel H E

    2007-05-16

    We describe the synthesis and the solution properties of sheet- and disclike Janus particles, containing an inner crosslinked polybutadiene (PB) layer and two different outer sides of polystyrene (PS) and poly(tert-butyl methacrylate) (PtBMA). The structures formed upon adsorption of the flat Janus particles onto solid substrates as well as in THF solution are investigated. The Janus discs are obtained in a template-assisted synthetic pathway followed by sonication. Selectively crosslinking the lamellar PB domains in a well-ordered lamellar microphase-separated bulk morphology of PS-block-PB-block-PtBMA (SBT) block terpolymers leads to the conservation of the compartmentalization of the two outer blocks. Sonication of the crosslinked block terpolymer templates renders soluble sheet- and disclike Janus particles, the size of which can be tuned from the micrometer range down to the nanometer scale. Small-angle X-ray scattering, transmission electron microscopy, dynamic light scattering, scanning force microscopy, and scanning electron microscopy are used to characterize the template-assisted synthetic process and the solution properties. Cryogenic transmission electron microscopy in THF and TEM of particles, embedded into a photo-crosslinkable silicon oil, indicate a supramolecular aggregation behavior of the Janus discs in concentrated solutions. Pendant drop tensiometry demonstrates that Janus sheets and discs can be used to stabilize liquid-liquid interfaces, rendering these materials interesting for future applications. PMID:17441717

  18. Valve assembly having remotely replaceable bearings

    DOEpatents

    Johnson, Evan R.; Tanner, David E.

    1980-01-01

    A valve assembly having remotely replaceable bearings is disclosed wherein a valve disc is supported within a flow duct for rotation about a pair of axially aligned bearings, one of which is carried by a spindle received within a diametral bore in the valve disc, and the other of which is carried by a bearing support block releasably mounted on the duct circumferentially of an annular collar on the valve disc coaxial with its diametrical bore. The spindle and bearing support block are adapted for remote removal to facilitate servicing or replacement of the valve disc support bearings.

  19. Comparison of Hybrid Constructs with 2-Level Artificial Disc Replacement and 2-Level Anterior Cervical Discectomy and Fusion for Surgical Reconstruction of the Cervical Spine: A Kinematic Study in Whole Cadavers

    PubMed Central

    Liu, Baoge; Zeng, Zheng; Van Hoof, Tom; Kalala, Jean Pierre; Liu, Zhenyu; Wu, Bingxuan

    2015-01-01

    Background Multi-level cervical degeneration of the spine is a common clinical pathology that is often repaired by anterior cervical discectomy and fusion (ACDF). The aim of this study was to investigate the kinematics of the cervical spine after hybrid surgery compared with 2-level ACDF. Material/Methods Five freshly frozen, unembalmed whole human cadavers were used including 3 males and 2 females with a mean age of 51±8 years. After evaluating the intact spine for range of motion (ROM), sagittal alignment and instantaneous center of rotation (ICR), each cadaver underwent 4 consecutive surgeries: 2-level artificial disc replacement (ADR) from C4 to C6 (ADR surgery); 2-level ACDF from C4 to C6 (ACDF surgery); hybrid C4–5 ACDF and C5–6 ADR (ACDF+ADR surgery); and hybrid C4–5 ADR and C5–6 ACDF (ADR+ACDF surgery). The ROM and ICR of adjacent intact segments (C3–4; C6–7), and whole sagittal alignment were revaluated. Results Two-level ACDF resulted in increased ROM at C3–4 and C6–7 compared with intact spine. ROM was significantly different to intact spine using ACDF surgery at C3–C4 and C6–C7 and ROM was increased with ACDF+ADR surgery at C6–C7 (all P<0.05). No improvement in sagittal alignment was observed with any approach. The localization of the ICR shifted upwards and anteriorly at C3–C4 after reconstruction. ICR changes at C3–C4 were greatest for ADR+ACDF surgery and were significantly different to ACDF surgery (P<0.05), but not between ADR surgery and ACDF+ADR surgery. At C6–C7, the ICR was more posterior and superior than in the intact condition. The greatest change in ICR was observed in ACDF surgery at the C6–C7 level, significantly different from the other groups (P<0.05). Conclusions For 2-level reconstruction, hybrid surgery and ADR did not alter ROM and minimally changed ICR at the adjacent-level. The type of surgery had a significant impact on the ICR location. This suggests that hybrid surgery may be a viable option for 2

  20. Redundant disc

    NASA Technical Reports Server (NTRS)

    Barack, W. N.; Domas, P. A.; Beekman, S. W. (Inventor)

    1978-01-01

    A rotatable disc is described that consists of parallel plates tightly joined together for rotation about a hub. Each plate is provided with several angularly projecting spaced lands. The lands of each plate are interposed in alternating relationship between the lands of the next adjacent plate. In this manner, circumferential displacement of adjacent sectors in any one plate is prevented in the event that a crack develops. Each plate is redundantly sized so that, in event of structural failure of one plate, the remaining plates support a proportionate share of the load of the failed plate. The plates are prevented from separating laterally through the inclusion of generally radially extending splines which are inserted to interlock cooperating, circumferentially adjacent lands.

  1. Intervertebral disc disease.

    PubMed

    Simpson, S T

    1992-07-01

    This article describes the functional anatomy of intervertebral discs and their relationship to the vertebrae and spinal cord. The pathologic events and clinical complications of intervertebral disc disease are described. A discussion of proper staging of disc disease and appropriate conservative management of degenerative disc disease is included. PMID:1641922

  2. Broken discs: warp propagation in accretion discs

    NASA Astrophysics Data System (ADS)

    Nixon, Christopher J.; King, Andrew R.

    2012-04-01

    We simulate the viscous evolution of an accretion disc around a spinning black hole. In general, any such disc is misaligned, and warped by the Lense-Thirring effect. Unlike previous studies, we use effective viscosities constrained to be consistent with the internal fluid dynamics of the disc. We find that non-linear fluid effects, which reduce the effective viscosities in warped regions, can promote breaking of the disc into two distinct planes. This occurs when the Shakura & Sunyaev dimensionless viscosity parameter α is ≲0.3 and the initial angle of misalignment between the disc and hole is ≳45°. The break can be a long-lived feature, propagating outwards in the disc on the usual alignment time-scale, after which the disc is fully co-aligned or counter-aligned with the hole. Such a break in the disc may be significant in systems where we know the inclination of the outer accretion disc to the line of sight, such as some X-ray binaries: the inner disc, and so any jets, may be noticeably misaligned with respect to the orbital plane.

  3. Disc-planet interactions in subkeplerian discs

    NASA Astrophysics Data System (ADS)

    Paardekooper, S.-J.

    2009-11-01

    Context: One class of protoplanetary disc models, the X-wind model, predicts strongly subkeplerian orbital gas velocities, a configuration that can be sustained by magnetic tension. Aims: We investigate disc-planet interactions in these subkeplerian discs, focusing on orbital migration for low-mass planets and gap formation for high-mass planets. Methods: We use linear calculations and nonlinear hydrodynamical simulations to measure the torque and look at gap formation. In both cases, the subkeplerian nature of the disc is treated as a fixed external constraint. Results: We show that, depending on the degree to which the disc is subkeplerian, the torque on low-mass planets varies between the usual type I torque and the one-sided outer Lindblad torque, which is also negative but an order of magnitude stronger. In strongly subkeplerian discs, corotation effects can be ignored, making migration fast and inward. Gap formation near the planet's orbit is more difficult in such discs, since there are no resonances close to the planet accommodating angular momentum transport. The location of the gap is shifted inwards with respect to the planet, leaving the planet on the outside of a surface density depression. Conclusions: Depending on the degree to which a protoplanetary disc is subkeplerian, disc-planet interactions can be very different from the usual Keplerian picture, making these discs in general more hazardous for young planets.

  4. Annulo-nucleoplasty using Disc-FX in the management of lumbar disc pathology: Early results

    PubMed Central

    Kumar, Aravind; Siddharth M, Shah; Sambhav P, Shah; Tan, Justin

    2014-01-01

    Background Back pain due to Lumbar Disc Disease is a major clinical problem. The treatment options range from physiotherapy to fusion surgery. A number of minimally invasive procedures have also been developed in the recent past for its management. Disc-FX is a new minimally invasive technique that combines percutaneous discectomy, nuclear ablation and annular modification. Literature on its role in the management of lumbar disc pathology is scarce. Methods We included 24 consecutive patients who underwent the Disc-FX for back pain due to lumbar disc pathology non-responsive to non-operative treatment for a period of at least 6 months. Based on Magnetic Resonance Imaging (MRI) these patients fell into 2 groups – those with degenerative disc disease (DDD) (n = 12) and those with a contained lumbar disc herniation (CLDH)(n = 12). They were evaluated using the Visual analogue scale (VAS), Oswestry Disability Index (ODI) and Short Form-36 (SF-36) scores preoperatively and postoperatively. Results The mean age was 37.9 years (21-53 years). There were 17 males and 7 females. One patient in each subgroup was excluded from the final evaluation. Significant improvement was seen in all outcome measures. The overall rate of reintervention for persistent symptoms was 18.18% (4/22); in the CLDH subgroup, it was 36.36% (4/11). Conclusions and level of evidence Early results after the Disc-FX procedure suggest that it s a reasonable treatment option for patients with back pain due to lumbar disc disease, especially for those with DDD who fail conservative treatment. It could be an alternative to procedures like fusion or disc replacement. This study presents Level IV evidence. Clinical relevance We feel that our study establishes Disc-FX as a modality of treating symptomatic lumbar disc disease due to DDD. However, longer term prospective studies are needed to prove this and to evaluate its role in the treatment of patients with CLDH. PMID:25694914

  5. How Does Lumbar Degenerative Disc Disease Affect the Disc Deformation at the Cephalic Levels In Vivo?

    PubMed Central

    Wang, Shaobai; Xia, Qun; Passias, Peter; Li, Weishi; Wood, Kirkham; Li, Guoan

    2013-01-01

    level and the level one above experienced higher tensile and shear deformations during end ranges of lumbar motion in the patients with DDD before surgical treatments when compared with the healthy subjects. The larger disc deformations at the cephalic segments were otherwise not detectable using conventional magnetic resonance imaging techniques. Future studies should investigate the effect of surgical treatments, such as fusion or disc replacement, on the biomechanics of the adjacent segments during end ranges of lumbar motion. PMID:21245781

  6. Fusion versus Bryan Cervical Disc in two-level cervical disc disease: a prospective, randomised study

    PubMed Central

    Nie, Lin; Zhang, Li; Hou, Yong

    2008-01-01

    In this prospective study, our aim was to compare the functional results and radiographic outcomes of fusion and Bryan Cervical Disc replacement in the treatment of two-level cervical disc disease. A total of 65 patients with two-level cervical disc disease were randomly assigned to two groups, those operated on with Bryan Cervical Disc replacement (31) and those operated on with anterior cervical fusion with an iliac crest autograft and plate (34). Clinical evaluation was carried out using the visual analogue scale (VAS), the Short Form 36 (SF-36) and the neck disability index (NDI) during a two year follow-up. Radiological evaluation sought evidence of range of motion, stability and subsidence of the prosthesis. Substantial reduction in NDI scores occurred in both groups, with greater percent improvement in the Bryan group (P = 0.023). The arm pain VAS score improvement was substantial in both groups. Bryan artificial cervical disc replacement seems reliable and safe in the treatment of patients with two-level cervical disc disease. PMID:18956190

  7. Ankle replacement

    MedlinePlus

    Ankle arthroplasty - total; Total ankle arthroplasty; Endoprosthetic ankle replacement; Ankle surgery ... Ankle replacement surgery is most often done while you are under general anesthesia. This means you will ...

  8. Video Discs in Education.

    ERIC Educational Resources Information Center

    Barker, Philip

    1986-01-01

    This discussion of the use of images in learning processes focuses on recent developments in optical storage disc technology, particularly compact disc read-only (CD-ROM) and optical video discs. Interactive video systems and user interfaces are described, and applications in education and industry in the United Kingdom are reviewed. (Author/LRW)

  9. Turbine disc sealing assembly

    DOEpatents

    Diakunchak, Ihor S.

    2013-03-05

    A disc seal assembly for use in a turbine engine. The disc seal assembly includes a plurality of outwardly extending sealing flange members that define a plurality of fluid pockets. The sealing flange members define a labyrinth flow path therebetween to limit leakage between a hot gas path and a disc cavity in the turbine engine.

  10. Pitfalls in archaeoastronomy: with examples from Mesoamerica.

    NASA Astrophysics Data System (ADS)

    Köhler, U.

    The kinds of pitfalls to be treated in this paper have been grouped into three categories: uncritical postulation of astronomical links, overinterpretation of alignments, and ethnocentric application of recent European concepts of space and time.

  11. Smart Sensors: Advantages and Pitfalls

    NASA Astrophysics Data System (ADS)

    French, Paddy James

    For almost 50 years, silicon sensors have been on the market. There have been many examples of success stories for simple silicon sensors, such as the Hall plate and photo-diode. These have found mass-market applications. The development of micromachining techniques brought pressure sensors and accelerometers into the market and later the gyroscope. These have also achieved mass-market. The remaining issue is how far to integrate. Many of the devices on the market use a simple sensor with external electronics or read-out electronics in the same package (system-in-a-package). However, there are also many examples of fully integrated sensors (smart sensors) where the whole system is integrated into a single chip. If the application and the device technology permit this, there can be many advantages. A broader look at sensors shows a wealth of integrated devices. The critical issues are reliability and packaging if these devices are to find the applications. A number of silicon sensors and actuators have shown great commercial success, but still many more have to find their way out of the laboratory. This paper will examine the development of the technologies, some of the success stories and the opportunities for integrated Microsystems as well as the pitfalls.

  12. ROI, Pitfalls and Best Practices with an Enterprise Smart Card Deployment

    NASA Astrophysics Data System (ADS)

    Hoyer, Philip

    This paper will describe the highlights of the ActivIdentity sponsored Datamonitor study into Return On Investment (ROI) when implementing smart cards in the enterprise in the following areas: physical and logical access convergence, remote access when replacing OTP tokens and Enterprise Single Sign-On. It also provides additional information about the pitfalls to avoid when implementing smart cards and describes best practices for deployment.

  13. Hip Replacement

    MedlinePlus

    ... replacement is an operation in which a damaged hip joint is removed and replaced with an artificial joint. ... are many medical conditions that can damage the hip joint. (Watch the video to learn about what goes ...

  14. Hip Replacement

    MedlinePlus

    ... surgeon removes damaged cartilage and bone from your hip joint and replaces them with new, man-made parts. A hip replacement can Relieve pain Help your hip joint work better Improve walking and other movements The ...

  15. Crystallization of Self-Propelled Hard Discs.

    PubMed

    Briand, G; Dauchot, O

    2016-08-26

    We experimentally study the crystallization of a monolayer of vibrated discs with a built-in polar asymmetry, a model system of active liquids, and contrast it with that of vibrated isotropic discs. Increasing the packing fraction ϕ, the quasicontinuous crystallization reported for isotropic discs is replaced by a transition, or a crossover, towards a "self-melting" crystal. Starting from the liquid phase and increasing the packing fraction, clusters of dense hexagonal-ordered packed discs spontaneously form, melt, split, and merge, leading to a highly intermittent and heterogeneous dynamics. For a packing fraction larger than ϕ^{*}, a few large clusters span the system size. The cluster size distribution is monotonically decreasing for ϕ<ϕ^{*}, nonmonotonic for ϕ>ϕ^{*}, and is a power law at the transition. The system is, however, never dynamically arrested. The clusters permanently melt from place to place, forming droplets of an active liquid which rapidly propagate across the system. This self-melting crystalline state subsists up to the highest possible packing fraction, questioning the stability of the crystal for active discs unless it is at ordered close packing. PMID:27610889

  16. Lumbar Degenerative Disc Disease: Current and Future Concepts of Diagnosis and Management

    PubMed Central

    Taher, Fadi; Essig, David; Lebl, Darren R.; Hughes, Alexander P.; Sama, Andrew A.; Cammisa, Frank P.; Girardi, Federico P.

    2012-01-01

    Low back pain as a result of degenerative disc disease imparts a large socioeconomic impact on the health care system. Traditional concepts for treatment of lumbar disc degeneration have aimed at symptomatic relief by limiting motion in the lumbar spine, but novel treatment strategies involving stem cells, growth factors, and gene therapy have the theoretical potential to prevent, slow, or even reverse disc degeneration. Understanding the pathophysiological basis of disc degeneration is essential for the development of treatment strategies that target the underlying mechanisms of disc degeneration rather than the downstream symptom of pain. Such strategies ideally aim to induce disc regeneration or to replace the degenerated disc. However, at present, treatment options for degenerative disc disease remain suboptimal, and development and outcomes of novel treatment options currently have to be considered unpredictable. PMID:22567411

  17. CD-ROM: Potential and Pitfalls.

    ERIC Educational Resources Information Center

    Dreiss, L. Jack; Bashir, Shahzad

    1990-01-01

    Examines issues surrounding CD-ROM as an organizational information management tool: (1) the CD-ROM market; (2) pitfalls, including compatibility, effect on existing information systems, fear of obsolescence, protection of sensitive information, and lack of successful role models; and (3) factors that will fuel growth, including greater…

  18. Pitfalls and Success of Distance Learning.

    ERIC Educational Resources Information Center

    Rendon, Marie Egbert

    This report discusses the pitfalls and success of distance learning programs. The report covers instructional alternatives of telecourse, linked courses, computer-aided learning, correspondence courses, and audio/video instruction. Sixteen concerns for distance learning programs are identified; for example: (1) registration procedures for distance…

  19. Precision diagnostic disc injections.

    PubMed

    Fortin, J D

    2000-07-01

    Spinal pain is an important public health problem affecting the population indiscriminately. The structures responsible for pain in the spine include the vertebrae, intervertebral discs, spinal cord, nerve roots, facet joints, ligaments, muscles, atlanto-occipital joints, atlanto-axial joints, and sacroiliac joints. Even though disc herniation, facet joints, strained muscles, and torn ligaments have been attributed to be the cause of most spinal pain, either in the neck and upper extremities, upper and mid back, or low back and lower extremities, disorders of the disc other than disc herniation have been implicated more frequently than any other disorders. Once stifled by misinformation, discography now has applications in a number of clinical settings. While cervical and lumbar discography is well studied and well known, thoracic discography is in its nascent stages of clinical application. The value of discography lies in its ability to produce pain and thereby identify a "pain generator." This allows treatment to be based on the specific cause of pain. The three primary components of diagnostic disc injection are: provocation/analgesia, discometry, and nucleography. Despite the recent exponential growth of noninvasive spinal technology, diagnostic disc injection remains the sole direct method for definitively determining whether a disc is a physiological pain generator. It is clear that discography is a safe and powerful complement to the overall clinical context. PMID:16906185

  20. Percutaneous laser disc decompression.

    PubMed

    Choy, D S

    1995-06-01

    Herniated disc disease has an incidence of 1.7% in the U.S. Heretofore, open operative procedures were the rule for this condition when conservative measures were ineffective. Choy and Ascher introduced this new technique in February 1986 using a Nd:YAG laser introduced into the disc through an optical fiber in a needle. Percutaneous laser disc decompression is based on the principle that in an enclosed hydraulic space, such as an intact disc, a small reduction in volume is associated with a disproportionate fall in pressure. In the disc, this partial vacuum causes the herniated portion to move away from the nerve root back toward the center of the disc. This technique has been taught worldwide and is being performed in most of Europe, Japan, the United States, and Korea. In this special issue devoted to percutaneous laser disc decompression (PLDD), we will set forth the basic science of PLDD, patient selection, use of the holmium:YAG, and the Nd:YAG lasers, operative technique, and results. PMID:10150634

  1. Investigation of Product Performance of Al-Metal Matrix Composites Brake Disc using Finite Element Analysis

    NASA Astrophysics Data System (ADS)

    Fatchurrohman, N.; Marini, C. D.; Suraya, S.; Iqbal, AKM Asif

    2016-02-01

    The increasing demand of fuel efficiency and light weight components in automobile sectors have led to the development of advanced material parts with improved performance. A specific class of MMCs which has gained a lot of attention due to its potential is aluminium metal matrix composites (Al-MMCs). Product performance investigation of Al- MMCs is presented in this article, where an Al-MMCs brake disc is analyzed using finite element analysis. The objective is to identify the potentiality of replacing the conventional iron brake disc with Al-MMCs brake disc. The simulation results suggested that the MMCs brake disc provided better thermal and mechanical performance as compared to the conventional cast iron brake disc. Although, the Al-MMCs brake disc dissipated higher maximum temperature compared to cast iron brake disc's maximum temperature. The Al-MMCs brake disc showed a well distributed temperature than the cast iron brake disc. The high temperature developed at the ring of the disc and heat was dissipated in circumferential direction. Moreover, better thermal dissipation and conduction at brake disc rotor surface played a major influence on the stress. As a comparison, the maximum stress and strain of Al-MMCs brake disc was lower than that induced on the cast iron brake disc.

  2. Shoulder replacement

    MedlinePlus

    ... the opening at the end of the shoulder blade, called the socket. This type of joint allows ... head. The socket part (glenoid) of your shoulder blade will be replaced with a smooth plastic shell ( ...

  3. Knee Replacement

    MedlinePlus

    ... doctor may recommend it if you have knee pain and medicine and other treatments are not helping you anymore. When you have a total knee replacement, the surgeon removes damaged cartilage and bone ...

  4. Herniated Lumbar Disc

    MedlinePlus

    ... 50. A herniated lumbar disc may also cause back pain, although back pain alone (without leg pain) can have many causes ... 90% success); surgery is less effective in relieving back pain. Nonsurgical treatment Your doctor may prescribe nonsurgical treatments ...

  5. Herniated lumbar disc

    PubMed Central

    2011-01-01

    Introduction Herniated lumbar disc is a displacement of disc material (nucleus pulposus or annulus fibrosis) beyond the intervertebral disc space. The highest prevalence is among people aged 30 to 50 years, with a male to female ratio of 2:1. There is little evidence to suggest that drug treatments are effective in treating herniated disc. Methods and outcomes We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of drug treatments, non-drug treatments, and surgery for herniated lumbar disc? We searched: Medline, Embase, The Cochrane Library, and other important databases up to June 2010 (Clinical Evidence reviews are updated periodically; please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA). Results We found 37 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions. Conclusions In this systematic review, we present information relating to the effectiveness and safety of the following interventions: acupuncture, advice to stay active, analgesics, antidepressants, bed rest, corticosteroids (epidural injections), cytokine inhibitors (infliximab), discectomy (automated percutaneous, laser, microdiscectomy, standard), exercise therapy, heat, ice, massage, muscle relaxants, non-steroidal anti-inflammatory drugs (NSAIDs), percutaneous disc decompression, spinal manipulation, and traction. PMID:21711958

  6. Pitfalls in diagnosing diabetic foot infections.

    PubMed

    Peters, Edgar J

    2016-01-01

    Although the diagnosis of a diabetic foot infection is made based on clinical symptoms and signs, we also use blood laboratory, microbiological and radiological studies to make treatment decisions. All of these diagnostic studies have pitfalls that can lead to a delay in diagnosis. Such delays will likely lead to further tissue damage and to a higher chance of amputation. One of these pitfalls is that some clinicians rely on microbiological, rather than clinical data, to diagnose infection. Though subjective by nature, clinical signs predict outcome of foot infections accurately. Another pitfall is that microbiological data can be misleading. All wounds harbour microorganisms; therefore, a positive wound culture does not mean that a wound is infected. Furthermore, the outcome of cultures of wound swabs does not correlate well with culture results of tissue biopsies. Therapy guidance by wound swab will likely lead to overtreatment of non-pathogenic organisms. Genotyping might have a role in identifying previously unrecognized (combinations of) pathogens in diabetic foot infection, bacteria in sessile phenotype and non-culturable pathogens, e.g. in cases where antibiotics have already been administered. One more pitfall is that the diagnosis of osteomyelitis remains difficult. Although the result of percutaneous bone biopsy is the reference standard for osteomyelitis, some other diagnostic modalities can aid in the diagnosis. A combination of several of these diagnostic tests is probably a good strategy to achieve a higher diagnostic accuracy. Relying on a single test will likely lead to misidentification of patients with osteomyelitis with associated overtreatment and undertreatment. PMID:26813617

  7. Pitfalls of cholescintigraphy. A case report

    SciTech Connect

    Strickler, S.; Park, H.M.

    1982-12-01

    A /sup 99m/Tc PIPIDA scan was performed in a young auto accident victim who had a transient rise in serum bilirubin level. Initially, the stasis of activity in the right ureter was mistaken for activity in the common bile duct. Misinterpretation of biliary imaging studies can be prevented with awareness of pitfalls and readiness to obtain delayed images and additional images in different projections.

  8. Condylar Osteochondroma Treated with Total Condylectomy and Preservation of the Articular Disc: A Case Report

    PubMed Central

    Dominguez, Manuel Fernandez; Castillo, Jose Luis Del; Guerra, Mario Muñoz; Sanchez, Ruth Sanchez; La Plata, Maria Mancha De

    2014-01-01

    Osteochondroma is frequently found in the general skeleton but is rare in the condylar region of the mandible. We report a case of an osteochondroma of large size and rapid growth in the mandibular condyle, which was treated with total condylectomy and condylar replacement with a costochondral graft and preservation of the articular disc. In cases with a healthy and well-positioned articular disc, it may be preserved with no need of disc repositioning. PMID:26000086

  9. Avoiding common pitfalls when clustering biological data.

    PubMed

    Ronan, Tom; Qi, Zhijie; Naegle, Kristen M

    2016-01-01

    Clustering is an unsupervised learning method, which groups data points based on similarity, and is used to reveal the underlying structure of data. This computational approach is essential to understanding and visualizing the complex data that are acquired in high-throughput multidimensional biological experiments. Clustering enables researchers to make biological inferences for further experiments. Although a powerful technique, inappropriate application can lead biological researchers to waste resources and time in experimental follow-up. We review common pitfalls identified from the published molecular biology literature and present methods to avoid them. Commonly encountered pitfalls relate to the high-dimensional nature of biological data from high-throughput experiments, the failure to consider more than one clustering method for a given problem, and the difficulty in determining whether clustering has produced meaningful results. We present concrete examples of problems and solutions (clustering results) in the form of toy problems and real biological data for these issues. We also discuss ensemble clustering as an easy-to-implement method that enables the exploration of multiple clustering solutions and improves robustness of clustering solutions. Increased awareness of common clustering pitfalls will help researchers avoid overinterpreting or misinterpreting the results and missing valuable insights when clustering biological data. PMID:27303057

  10. [Laser ablation of intervertebral disc: animal experiment].

    PubMed

    Qi, Q; Dang, G D; Cai, Q L

    1994-03-01

    The lumbar intervertebral discs (L3-6) were ablated through a transperitoneal approach in 12 adult dogs by using Nd: YAG laser (1.06 microns) with a 600 microns quartz fiber. The status of limbs motion and sphincter (bladder, bowel) was observed for evaluating the safety of laser irradiation. After irradiation, the animals were sacrificed at prescribed intervals of up to 40 weeks (2, 4, 8, 12 and 40 weeks after operation). The lumbar intervertebral discs were harvested and subjected to light microscopic observation. No dog had suffered from neurogenic dysfunction of limb motion and sphincter. Histological findings immediately after the irradiation showed the disc was vaporized and a cavity was made. After 2 and 4 weeks, fibrous tissues began to proliferate, but cartilaginous tissues replaced the fibrous tissues 12 weeks after the laser irradiation. No new bone formation was found within 40 weeks after operation. On the basis of this study and our previous cadaveric study, percutaneous laser disc decompression (PLDD) was applied in clinical practice in march of 1993. 10 patients underwent PLDD utilizing the same laser equipment. The average follow-up was 3 months. According to the Macnab's criteria, there was an excellent response in 7 patients and a good response in 3. PMID:7842915

  11. Lung cancer cytology: potential pitfalls and mimics - a review

    PubMed Central

    Idowu, Michael O; Powers, Celeste N

    2010-01-01

    Cytology is increasingly being used in the evaluation of lung lesions. There are several potential pitfalls and mimics encountered in the evaluation of respiratory cytology specimens, making interpretation of respiratory cytology challenging. Familiarity with the mimics and the pitfalls is essential in avoiding a misdiagnosis because a false positive or false negative diagnosis may have significant management implications. This article focuses on the main classification of primary lung carcinoma - small cell carcinoma, adenocarcinoma and squamous cell carcinoma - with potential mimics discussed under each tumor category. We have attempted to separate pitfalls from common potential mimics and have suggested general rules when such pitfalls are encountered. PMID:20490328

  12. The ProDisc artificial disc: insertion technique.

    PubMed

    Aryan, Henry E; Acosta, Frank L; Ames, Christopher P

    2005-10-01

    The ProDisc artificial lumbar disc was designed for use in treatment of degenerative lumbar disease. The disc is implanted using an anterior approach to the lumbar spine with the assistance of intraoperative fluoroscopy. A variety of insertion instruments guide the surgeon through this process. The disc is implanted via an anterior approach, generally retroperitoneally but on occasion transperitoneally. The different approaches and insertion technique are described in this article. PMID:16326288

  13. Cervical disc arthroplasty: Pros and cons

    PubMed Central

    Moatz, Bradley; Tortolani, P. Justin

    2012-01-01

    Background: Cervical disc arthroplasty has emerged as a promising potential alternative to anterior cervical discectomy and fusion (ACDF) in appropriately selected patients. Despite a history of excellent outcomes after ACDF, the question as to whether a fusion leads to adjacent segment degeneration remains unanswered. Numerous US investigational device exemption trials comparing cervical arthroplasty to fusion have been conducted to answer this question. Methods: This study reviews the current research regarding cervical athroplasty, and emphasizes both the pros and cons of arthroplasty as compared with ACDF. Results: Early clinical outcomes show that cervical arthroplasty is as effective as the standard ACDF. However, this new technology is also associated with an expanding list of novel complications. Conclusion: Although there is no definitive evidence that cervical disc replacement reduces the incidence of adjacent segment degeneration, it does show other advantages; for example, faster return to work, and reduced need for postoperative bracing. PMID:22905327

  14. Shoulder replacement - discharge

    MedlinePlus

    Total shoulder arthroplasty - discharge; Endoprosthetic shoulder replacement - discharge; Partial shoulder replacement - discharge; Partial shoulder arthroplasty - discharge; Replacement - shoulder - discharge; ...

  15. The Chemistry of Optical Discs.

    ERIC Educational Resources Information Center

    Birkett, David

    2002-01-01

    Explains the chemistry used in compact discs (CD), digital versatile discs (DVD), and magneto-optical (MO) discs focusing on the steps of initial creation of the mold, the molding of the polycarbonate, the deposition of the reflective layers, the lacquering of the CDs, and the bonding of DVDs. (Contains 15 references.) (YDS)

  16. How do accretion discs break?

    NASA Astrophysics Data System (ADS)

    Dogan, Suzan

    2016-07-01

    Accretion discs are common in binary systems, and they are often found to be misaligned with respect to the binary orbit. The gravitational torque from a companion induces nodal precession in misaligned disc orbits. In this study, we first calculate whether this precession is strong enough to overcome the internal disc torques communicating angular momentum. We compare the disc precession torque with the disc viscous torque to determine whether the disc should warp or break. For typical parameters precession wins: the disc breaks into distinct planes that precess effectively independently. To check our analytical findings, we perform 3D hydrodynamical numerical simulations using the PHANTOM smoothed particle hydrodynamics code, and confirm that disc breaking is widespread and enhances accretion on to the central object. For some inclinations, the disc goes through strong Kozai cycles. Disc breaking promotes markedly enhanced and variable accretion and potentially produces high-energy particles or radiation through shocks. This would have significant implications for all binary systems: e.g. accretion outbursts in X-ray binaries and fuelling supermassive black hole (SMBH) binaries. The behaviour we have discussed in this work is relevant to a variety of astrophysical systems, for example X-ray binaries, where the disc plane may be tilted by radiation warping, SMBH binaries, where accretion of misaligned gas can create effectively random inclinations and protostellar binaries, where a disc may be misaligned by a variety of effects such as binary capture/exchange, accretion after binary formation.

  17. Revival of the Jumping Disc

    ERIC Educational Resources Information Center

    Ucke, C.; Schlichting, H-J.

    2009-01-01

    Snap discs made of bimetal have many technical applications as thermostats. Jumping discs are a toy version of such snap discs. Besides giving technical information, we describe physical investigations. We show especially how, through simple measurements and calculations, you can determine the initial speed ([approximately equal to]3.5 m…

  18. Learning Language on Disc.

    ERIC Educational Resources Information Center

    Desmarais, Norman

    1995-01-01

    Presents a comparison of two types of compact disc (CD-ROM) foreign language tutorials: (1) those made by publishers who favor an immersion approach; and (2) those made by publishers who use grammar-based approaches. Both types of CD-ROMs address various age groups, skill levels, and learning styles. (JMV)

  19. The DISC Quotient

    NASA Astrophysics Data System (ADS)

    Elliott, John R.; Baxter, Stephen

    2012-09-01

    D.I.S.C: Decipherment Impact of a Signal's Content. The authors present a numerical method to characterise the significance of the receipt of a complex and potentially decipherable signal from extraterrestrial intelligence (ETI). The purpose of the scale is to facilitate the public communication of work on any such claimed signal, as such work proceeds, and to assist in its discussion and interpretation. Building on a "position" paper rationale, this paper looks at the DISC quotient proposed and develops the algorithmic steps and comprising measures that form this post detection strategy for information dissemination, based on prior work on message detection, decipherment. As argued, we require a robust and incremental strategy, to disseminate timely, accurate and meaningful information, to the scientific community and the general public, in the event we receive an "alien" signal that displays decipherable information. This post-detection strategy is to serve as a stepwise algorithm for a logical approach to information extraction and a vehicle for sequential information dissemination, to manage societal impact. The "DISC Quotient", which is based on signal analysis processing stages, includes factors based on the signal's data quantity, structure, affinity to known human languages, and likely decipherment times. Comparisons with human and other phenomena are included as a guide to assessing likely societal impact. It is submitted that the development, refinement and implementation of DISC as an integral strategy, during the complex processes involved in post detection and decipherment, is essential if we wish to minimize disruption and optimize dissemination.

  20. The Teddy Bears' Disc.

    ERIC Educational Resources Information Center

    Laurillard, Diana

    1985-01-01

    Reports an evaluation of the Teddy Bear disc, an interactive videodisc developed at the Open University for a second-level course in metallurgy and materials technology. Findings from observation of students utilizing the videodisc are reviewed; successful design features and design problems are considered; and development costs are outlined. (MBR)

  1. Pitfalls of Personal Development Plans--The User Perspective

    ERIC Educational Resources Information Center

    Grohnert, Therese; Beausaert, Simon; Segers, Mien

    2014-01-01

    This study was conducted to investigate which pitfalls users of personal development plans (PDPs) perceive in business and governmental organisations with mandatory PDP use. Hundred and thirty-one written statements of PDP users across three Dutch organisations were analysed and categorised into nine pitfalls. Next to an overall lack of use and…

  2. Bioinformatics in proteomics: application, terminology, and pitfalls.

    PubMed

    Wiemer, Jan C; Prokudin, Alexander

    2004-01-01

    Bioinformatics applies data mining, i.e., modern computer-based statistics, to biomedical data. It leverages on machine learning approaches, such as artificial neural networks, decision trees and clustering algorithms, and is ideally suited for handling huge data amounts. In this article, we review the analysis of mass spectrometry data in proteomics, starting with common pre-processing steps and using single decision trees and decision tree ensembles for classification. Special emphasis is put on the pitfall of overfitting, i.e., of generating too complex single decision trees. Finally, we discuss the pros and cons of the two different decision tree usages. PMID:15237926

  3. Pitfalls in colour photography of choroidal tumours

    PubMed Central

    Schalenbourg, A; Zografos, L

    2013-01-01

    Colour imaging of fundus tumours has been transformed by the development of digital and confocal scanning laser photography. These advances provide numerous benefits, such as panoramic images, increased contrast, non-contact wide-angle imaging, non-mydriatic photography, and simultaneous angiography. False tumour colour representation can, however, cause serious diagnostic errors. Large choroidal tumours can be totally invisible on angiography. Pseudogrowth can occur because of artefacts caused by different methods of fundus illumination, movement of reference blood vessels, and flattening of Bruch's membrane and sclera when tumour regression occurs. Awareness of these pitfalls should prevent the clinician from misdiagnosing tumours and wrongfully concluding that a tumour has grown. PMID:23238442

  4. Molecular replacement.

    PubMed

    Toth, Eric A

    2007-01-01

    As more protein structures are solved, the likelihood that current structural investigations will involve proteins for which there exists no homologous structure continually decreases. The extraction of phase information from diffraction experiments is one of several great barriers that crystallographers must overcome on the path to structure solution. One means to overcome this obstacle, the technique of molecular replacement, uses the structural similarity between proteins with similar sequences to give a good first estimate of the phases for the diffraction data of the protein of interest. The programs that execute this technique currently come in many flavors, from traditional Patterson-based methods, to stochastic searches in greater than three dimensions, to maximum likelihood-enhanced molecular replacement, each possessing unique advantages that can shake loose a recalcitrant solution. As crystallographers aim to solve larger macromolecular complexes that more faithfully depict the actors in cellular events, having existing phase information for parts of those biological machines will reinforce the technological advancements in data collection and structure solution that have already produced mammoth structures like the ribosome, yielding an ever-clearer picture of the inner workings of biology. PMID:17172763

  5. ISASS Policy Statement – Lumbar Artificial Disc

    PubMed Central

    Garcia, Rolando

    2015-01-01

    Purpose The primary goal of this Policy Statement is to educate patients, physicians, medical providers, reviewers, adjustors, case managers, insurers, and all others involved or affected by insurance coverage decisions regarding lumbar disc replacement surgery. Procedures This Policy Statement was developed by a panel of physicians selected by the Board of Directors of ISASS for their expertise and experience with lumbar TDR. The panel's recommendation was entirely based on the best evidence-based scientific research available regarding the safety and effectiveness of lumbar TDR. PMID:25785243

  6. Mechanotransduction in intervertebral discs

    PubMed Central

    Tsai, Tsung-Ting; Cheng, Chao-Min; Chen, Chien-Fu; Lai, Po-Liang

    2014-01-01

    Mechanotransduction plays a critical role in intracellular functioning—it allows cells to translate external physical forces into internal biochemical activities, thereby affecting processes ranging from proliferation and apoptosis to gene expression and protein synthesis in a complex web of interactions and reactions. Accordingly, aberrant mechanotransduction can either lead to, or be a result of, a variety of diseases or degenerative states. In this review, we provide an overview of mechanotransduction in the context of intervertebral discs, with a focus on the latest methods of investigating mechanotransduction and the most recent findings regarding the means and effects of mechanotransduction in healthy and degenerative discs. We also provide some discussion of potential directions for future research and treatments. PMID:25267492

  7. Biomechanics of Disc Degeneration

    PubMed Central

    Palepu, V.; Kodigudla, M.; Goel, V. K.

    2012-01-01

    Disc degeneration and associated disorders are among the most debated topics in the orthopedic literature over the past few decades. These may be attributed to interrelated mechanical, biochemical, and environmental factors. The treatment options vary from conservative approaches to surgery, depending on the severity of degeneration and response to conservative therapies. Spinal fusion is considered to be the “gold standard” in surgical methods till date. However, the association of adjacent level degeneration has led to the evolution of motion preservation technologies like spinal arthroplasty and posterior dynamic stabilization systems. These new technologies are aimed to address pain and preserve motion while maintaining a proper load sharing among various spinal elements. This paper provides an elaborative biomechanical review of the technologies aimed to address the disc degeneration and reiterates the point that biomechanical efficacy followed by long-term clinical success will allow these nonfusion technologies as alternatives to fusion, at least in certain patient population. PMID:22745914

  8. LUMBAR DISC HERNIATION

    PubMed Central

    Vialle, Luis Roberto; Vialle, Emiliano Neves; Suárez Henao, Juan Esteban; Giraldo, Gustavo

    2015-01-01

    Lumbar disc herniation is the most common diagnosis among the degenerative abnormalities of the lumbar spine (affecting 2 to 3% of the population), and is the principal cause of spinal surgery among the adult population. The typical clinical picture includes initial lumbalgia, followed by progressive sciatica. The natural history of disc herniation is one of rapid resolution of the symptoms (four to six weeks). The initial treatment should be conservative, managed through medication and physiotherapy, sometimes associated with percutaneous nerve root block. Surgical treatment is indicated if pain control is unsuccessful, if there is a motor deficit greater than grade 3, if there is radicular pain associated with foraminal stenosis, or if cauda equina syndrome is present. The latter represents a medical emergency. A refined surgical technique, with removal of the extruded fragment and preservation of the ligamentum flavum, resolves the sciatic symptoms and reduces the risk of recurrence over the long term. PMID:27019834

  9. The Formation and Fragmentation of Primordial Protostellar Discs

    NASA Astrophysics Data System (ADS)

    Clark, Paul C.; Glover, Simon C. O.; Smith, Rowan J.; Greif, Thomas H.; Klessen, Ralf S.; Bromm, Volker

    2010-11-01

    We study the formation and evolution of the protostellar discs that form around the first stars in the Universe. Using sink particles, we replace the gravitationally bound gas at densities higher than 1015 cm-3 and radii greater than 3 AU from the central protostellar core, with an accreting point mass that is able to gravitationally interact with the surrounding gas. We find the disc is gravitationally (or `Toomre') unstable, and is dominated by a strong m = 2 spiral mode. Although the angular momentum transport is dominated by a combination of gravitational torques and Reynolds stresses, which are extremely efficient mechanisms, the disc is unable to process the infalling material and grows increasingly gravitationally unstable. During the build-up of the disc, the temperature in the gas is regulated by a combination of H2 line cooling, collision-induced emission and H2 dissociation, which together help to offset heating from the gravitational collapse and feedback from the protostar. Once the disc starts to fragment, H2 dissociation keeps the gas almost isothermal as the collapse of the fragment progresses. The fragmentation occurs when the protostar/disc system is only 230 yr old and at a distance of ~20 AU from its sibling, by which point the central protostar has a mass of ~1 Msolar. Given the angular momentum of the new protostellar system, it is likely that the protostars will grow to become a massive binary system.

  10. Dynamics of an intervertebral disc prosthesis in human cadaveric spines.

    PubMed

    Meyers, Kathleen N; Campbell, Deirdre A; Lipman, Joseph D; Zhang, Kai; Myers, Elizabeth R; Girardi, Federico P; Cammisa, Frank P; Wright, Timothy M

    2007-09-01

    Low-back pain is a common, disabling medical condition, and one of the major causes is disc degeneration. Total disc replacements are intended to treat back pain by restoring disc height and re-establishing functional motion and stability at the index level. The objective of this study was to determine the effect on range of motion (ROM) and stiffness after implantation of the ProDisc-L device in comparison to the intact state. Twelve L5-S1 lumbar spine segments were tested in flexion/extension, lateral bending, and axial rotation with axial compressive loads of 600 N and 1,200 N. Specimens were tested in the intact state and after implantation with the ProDisc-L device. ROM was not significantly different in the implanted spines when compared to their intact state in flexion/extension and axial rotation but increased in lateral bending. Increased compressive load did not affect ROM in flexion/extension or axial rotation but did result in decreased ROM in lateral bending and increased stiffness in both intact and implanted spine segments. The ProDisc-L successfully restored or maintained normal spine segment motion. PMID:18751788

  11. Counter-rotating accretion discs

    NASA Astrophysics Data System (ADS)

    Dyda, S.; Lovelace, R. V. E.; Ustyugova, G. V.; Romanova, M. M.; Koldoba, A. V.

    2015-01-01

    Counter-rotating discs can arise from the accretion of a counter-rotating gas cloud on to the surface of an existing corotating disc or from the counter-rotating gas moving radially inwards to the outer edge of an existing disc. At the interface, the two components mix to produce gas or plasma with zero net angular momentum which tends to free-fall towards the disc centre. We discuss high-resolution axisymmetric hydrodynamic simulations of viscous counter-rotating discs for the cases where the two components are vertically separated and radially separated. The viscosity is described by an isotropic α-viscosity including all terms in the viscous stress tensor. For the vertically separated components, a shear layer forms between them and the middle part of this layer free-falls to the disc centre. The accretion rates are increased by factors of ˜102-104 over that for a conventional disc rotating in one direction with the same viscosity. The vertical width of the shear layer and the accretion rate are strongly dependent on the viscosity and the mass fraction of the counter-rotating gas. In the case of radially separated components where the inner disc corotates and the outer disc rotates in the opposite direction, a gap between the two components opens and closes quasi-periodically. The accretion rates are ≳25 times larger than those for a disc rotating in one direction with the same viscosity.

  12. Have protoplanetary discs formed planets?

    NASA Astrophysics Data System (ADS)

    Greaves, J. S.; Rice, W. K. M.

    2010-09-01

    It has recently been noted that many discs around T Tauri stars appear to comprise only a few Jupiter masses of gas and dust. Using millimetre surveys of discs within six local star formation regions, we confirm this result, and find that only a few per cent of young stars have enough circumstellar material to build gas giant planets, in standard core accretion models. Since the frequency of observed exoplanets is greater than this, there is a `missing-mass' problem. As alternatives to simply adjusting the conversion of dust flux to disc mass, we investigate three other classes of solution. Migration of planets could hypothetically sweep up the disc mass reservoir more efficiently, but trends in multiplanet systems do not support such a model, and theoretical models suggest that the gas accretion time-scale is too short for migration to sweep the disc. Enhanced inner-disc mass reservoirs are possible, agreeing with predictions of disc evolution through self-gravity, but not adding to millimetre dust flux as the inner disc is optically thick. Finally, the incidence of massive discs is shown to be higher at the protostellar stages, Classes 0 and I, where discs substantial enough to form planets via core accretion are abundant enough to match the frequency of exoplanets. Gravitational instability may also operate in the Class 0 epoch, where half the objects have potentially unstable discs of >~30 per cent of the stellar mass. However, recent calculations indicate that forming gas giants inside 50 au by instability is unlikely, even in such massive discs. Overall, the results presented suggest that the canonically `protoplanetary' discs of Class II T Tauri stars have globally low masses in dust observable at millimetre wavelengths, and conversion to larger bodies (anywhere from small rocks up to planetary cores) must already have occurred.

  13. Disc edge veins of Kraupa associated with optic disc drusen

    PubMed Central

    Díaz, Andrea; Almela, Miguel Angel

    2014-01-01

    Objective: Disc edge veins of Kraupa are a rare anomaly of the retinal venous system in which the main trunk of the retinal vein disappeared into the margin of the optic disc instead of its centre. Methods: A 40-year-old woman was detected to have an anomaly in her left optic disc in a routine eye examination. The eyes had an anomaly of the retinal venous system in which all branches of the retinal vein joined in a common trunk that entered the disc margin inferonasally. The central retinal artery issued from the centre of the disc separately of the venous system. B-scan ultrasonografhy revealed the presence of hyperechoic imaging at the optic nerve head in both eyes. Results: We describe the association of disc edge veins of Kraupa with optic disc drusen. Conclusion: Vascular complications of optic disc drusen hav been described. We don’t know the implication of disc edge veins in the pathogenesis of these complications.

  14. Enclosed rotary disc air pulser

    DOEpatents

    Olson, A. L.; Batcheller, Tom A.; Rindfleisch, J. A.; Morgan, John M.

    1989-01-01

    An enclosed rotary disc air pulser for use with a solvent extraction pulse olumn includes a housing having inlet, exhaust and pulse leg ports, a shaft mounted in the housing and adapted for axial rotation therein, first and second disc members secured to the shaft within the housing in spaced relation to each other to define a chamber therebetween, the chamber being in communication with the pulse leg port, the first disc member located adjacent the inlet port, the second disc member being located adjacent the exhaust port, each disc member having a milled out portion, the disc members positioned on the shaft so that as the shaft rotates, the milled out portions permit alternative cyclical communication between the inlet port and the chamber and the exhaust port and the chamber.

  15. Edge-on thick discs

    NASA Astrophysics Data System (ADS)

    Kasparova, A.; Katkov, I.; Chilingarian, I.; Silchenko, O.; Moiseev, A.; Borisov, S.

    2016-06-01

    Although thick stellar discs are detected in nearly all edge-on disc galaxies, their formation scenarios still remain a matter of debate. Due to observational difficulties, there is a lack of information about their stellar populations. Using the Russian 6-m telescope BTA we collected deep spectra of thick discs in three edge-on early-type disc galaxies located in different environments: NGC4111 in a dense group, NGC4710 in the Virgo cluster, and NGC5422 in a sparse group. We see intermediate age (4 ‑ 5 Gyr) metal rich ([Fe/H] ~ ‑0.2 ‑ 0.0 dex) stellar populations in NGC4111 and NGC4710. On the other hand, NGC5422 does not harbour young stars, its only disc is thick and old (10 Gyr) and its α-element abundance suggests a long formation epoch implying its formation at high redshift. Our results prove the diversity of thick disc formation scenarios.

  16. Experimental phasing: best practice and pitfalls

    PubMed Central

    McCoy, Airlie J.; Read, Randy J.

    2010-01-01

    Developments in protein crystal structure determination by experimental phasing are reviewed, emphasizing the theoretical continuum between experimental phasing, density modification, model building and refinement. Traditional notions of the composition of the substructure and the best coefficients for map generation are discussed. Pitfalls such as determining the enantiomorph, identifying centrosymmetry (or pseudo-symmetry) in the substructure and crystal twinning are discussed in detail. An appendix introduces com­bined real–imaginary log-likelihood gradient map coefficients for SAD phasing and their use for substructure completion as implemented in the software Phaser. Supplementary material includes animated probabilistic Harker diagrams showing how maximum-likelihood-based phasing methods can be used to refine parameters in the case of SIR and MIR; it is hoped that these will be useful for those teaching best practice in experimental phasing methods. PMID:20382999

  17. Potential Pitfalls in microRNA Profiling

    PubMed Central

    Chugh, Pauline; Dittmer, Dirk P.

    2013-01-01

    MicroRNAs (miRNAs) are small, noncoding RNAs that post-transcriptionally influence a wide range of cellular processes such as the host response to viral infection, innate immunity, cell cycle progression, migration and apoptosis through the inhibition of target mRNA translation. Due to the growing number of microRNAs and identification of their functional roles, miRNA profiling of many different sample types has become more expansive, especially with relevance to disease signatures. Here, we address some of the advantages and potential pitfalls of the currently available methods for miRNA expression profiling. Some of the topics discussed include isomiRNAs, comparison of different profiling platforms, normalization strategies and issues with regard to sample preparation and experimental analyses. PMID:22566380

  18. Microstructure Informed Tractography: Pitfalls and Open Challenges

    PubMed Central

    Daducci, Alessandro; Dal Palú, Alessandro; Descoteaux, Maxime; Thiran, Jean-Philippe

    2016-01-01

    One of the major limitations of diffusion MRI tractography is that the fiber tracts recovered by existing algorithms are not truly quantitative. Local techniques for estimating more quantitative features of the tissue microstructure exist, but their combination with tractography has always been considered intractable. Recent advances in local and global modeling made it possible to fill this gap and a number of promising techniques for microstructure informed tractography have been suggested, opening new and exciting perspectives for the quantification of brain connectivity. The ease-of-use of the proposed solutions made it very attractive for researchers to include such advanced methods in their analyses; however, this apparent simplicity should not hide some critical open questions raised by the complexity of these very high-dimensional problems, otherwise some fundamental issues may be pushed into the background. The aim of this article is to raise awareness in the diffusion MRI community, notably researchers working on brain connectivity, about some potential pitfalls and modeling choices that make the interpretation of the outcomes from these novel techniques rather cumbersome. Through a series of experiments on synthetic and real data, we illustrate practical situations where erroneous and severely biased conclusions may be drawn about the connectivity if these pitfalls are overlooked, like the presence of partial/missing/duplicate fibers or the critical importance of the diffusion model adopted. Microstructure informed tractography is a young but very promising technology, and by acknowledging its current limitations as done in this paper, we hope our observations will trigger further research in this direction and new ideas for truly quantitative and biologically meaningful analyses of the connectivity. PMID:27375412

  19. Microstructure Informed Tractography: Pitfalls and Open Challenges.

    PubMed

    Daducci, Alessandro; Dal Palú, Alessandro; Descoteaux, Maxime; Thiran, Jean-Philippe

    2016-01-01

    One of the major limitations of diffusion MRI tractography is that the fiber tracts recovered by existing algorithms are not truly quantitative. Local techniques for estimating more quantitative features of the tissue microstructure exist, but their combination with tractography has always been considered intractable. Recent advances in local and global modeling made it possible to fill this gap and a number of promising techniques for microstructure informed tractography have been suggested, opening new and exciting perspectives for the quantification of brain connectivity. The ease-of-use of the proposed solutions made it very attractive for researchers to include such advanced methods in their analyses; however, this apparent simplicity should not hide some critical open questions raised by the complexity of these very high-dimensional problems, otherwise some fundamental issues may be pushed into the background. The aim of this article is to raise awareness in the diffusion MRI community, notably researchers working on brain connectivity, about some potential pitfalls and modeling choices that make the interpretation of the outcomes from these novel techniques rather cumbersome. Through a series of experiments on synthetic and real data, we illustrate practical situations where erroneous and severely biased conclusions may be drawn about the connectivity if these pitfalls are overlooked, like the presence of partial/missing/duplicate fibers or the critical importance of the diffusion model adopted. Microstructure informed tractography is a young but very promising technology, and by acknowledging its current limitations as done in this paper, we hope our observations will trigger further research in this direction and new ideas for truly quantitative and biologically meaningful analyses of the connectivity. PMID:27375412

  20. Pitfalls of mechanical ventilation in Thailand.

    PubMed

    Bunburaphong, Thananchai

    2014-01-01

    Pitfalls in the respiratory care and mechanical ventilation for patients continue to prevail in intensive care unit (ICU) or in some hospital wards in Thailand. There are two reasons that explain this phenomenon. Firstly, there are no professional respiratory therapists in Thailand. Secondly, most caregivers do not possess the adequate knowledge and skills requiredfor respiratory care and for initiating, maintaining and weaning patients off mechanical ventilation. Physicians and nurses have to practice in respiratory care and mechanical ventilation without participating in adequate training during their undergraduate studies and postgraduate training. In reality, physicians pay almost no attention to respiratory care. They leave the respiratory toilet, ventilator changes and monitoring of the patients to nurses who have many other tasks to attend to. To solve this problem will require restructuring of the Thai healthcare system. The Parliament will need to pass a "Respiratory Therapy Profession Act" to certify "respiratory therapists " as a new, registered health profession. The Office of the Civil Service Commission has to take the responsibility for creating the job title and a job description for respiratory therapists. Academic institutes have to provide training courses in respiratory therapy and grant appropriate levels of diplomas or certificates in respiratory therapy. Did actics and clinical skills required for respiratory care have to be sufficiently integrated into the curricula for medical students as well as nursing students. Physicians and nurses need to master their skills and acquired appropriate knowledge in respiratory care and mechanical ventilation until we can assure the necessary number of registered or certified respiratory therapists here in Thailand to help avoid such pitfalls. PMID:24855857

  1. Numbered nasal discs for waterfowl

    USGS Publications Warehouse

    Bartonek, J.C.; Dane, C.W.

    1964-01-01

    Numbered nasal discs were successfully used in studies requiring large numbers of individually marked waterfowl. The procedure for constructing these discs is outlined. Blue-winged teal (Anas discors) with 5/8-inch discs, and canvasback (Aythya valisineria) and redhead (A. americana) with 3/4-inch discs can be individually identified up to 50 and 80 yards, respectively, with a gunstock-mounted, 20-power spotting scope. The particular value of these markers is their durability, the number of combinations possible, and the apparent absence of behavioral or mortality influence among such species as the blue-winged teal.

  2. The Pleasures and the Pitfalls of Plant Science Activities.

    ERIC Educational Resources Information Center

    Hershey, David R.

    2000-01-01

    Classroom plant activities have long been inexpensive, easy to do, and fun for students, and have become more central to biology teaching. Introduces some plant science activities and their pleasures and pitfalls. (ASK)

  3. Pitfalls in Using Electrophysiological Studies to Diagnose Neuromuscular Disorders

    PubMed Central

    Koo, Yong Seo; Cho, Charles S.

    2012-01-01

    Electrodiagnostic testing is used widely for the full characterization of neuromuscular disorders and for providing unique information on the processes underlying the pathology of peripheral nerves and muscles. However, such testing should be considered as an extension of anamnesis and physical examination, not as pathognomonic of a specific disease entity. There are many pitfalls that could lead to erroneous interpretation of electrophysiological study results when the studies are not performed properly or if they are performed in the presence of anatomical aberrations. The diagnostic reliability of electrodiagnostic studies can be improved and the associated pitfalls overcome if the physician is familiar with all of those possible pitfalls. In this article we discuss the most common and important pitfalls associated with electrodiagnostic medicine. PMID:22523508

  4. Preparation of ormetoprim sulfadimethoxine medicated discs for disc diffusion assay

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Romet (a blend of ormetoprim and sulfadimethoxine) is a typeA medicated article for the manufacture of medicated feed in the catfish industry. Recently, the commercial manufacture of ormetoprim–sulfadimethoxine susceptibility discs was discontinued. Ormetoprim–sulfadimethoxine discs were prepared at...

  5. The activL® Artificial Disc: a next-generation motion-preserving implant for chronic lumbar discogenic pain

    PubMed Central

    Yue, James J; Garcia, Rolando; Miller, Larry E

    2016-01-01

    Degeneration of the lumbar intervertebral discs is a leading cause of chronic low back pain in adults. Treatment options for patients with chronic lumbar discogenic pain unresponsive to conservative management include total disc replacement (TDR) or lumbar fusion. Until recently, only two lumbar TDRs had been approved by the US Food and Drug Administration − the Charité Artificial Disc in 2004 and the ProDisc-L Total Disc Replacement in 2006. In June 2015, a next-generation lumbar TDR received Food and Drug Administration approval − the activL® Artificial Disc (Aesculap Implant Systems). Compared to previous-generation lumbar TDRs, the activL® Artificial Disc incorporates specific design enhancements that result in a more precise anatomical match and allow a range of motion that better mimics the healthy spine. The results of mechanical and clinical studies demonstrate that the activL® Artificial Disc results in improved mechanical and clinical outcomes versus earlier-generation artificial discs and compares favorably to lumbar fusion. The purpose of this report is to describe the activL® Artificial Disc including implant characteristics, intended use, surgical technique, postoperative care, mechanical testing, and clinical experience to date. PMID:27274317

  6. Androgens and doping tests: genetic variation and pit-falls

    PubMed Central

    Rane, Anders; Ekström, Lena

    2012-01-01

    The large variation in disposition known for most drugs is also true for anabolic androgenic steroids. Genetic factors are probably the single most important cause of this variation. Further, there are reasons to believe that there is a corresponding variation in efficacy of doping agents. Doped individuals employ a large variety of doping strategies in respect of choice of substance, dose, dose interval, duration of treatment and use of other drugs for enforcement of effects or correction of side effects. Metabolic steps up-stream and down-stream of testosterone are genetically variable and contribute substantially to the variation in disposition of testosterone, the most common doping agent in sports and in society. Large inter- and intra-ethnic variation in testosterone glucuronidation and excretion is described as well as the pit-falls in evaluation of testosterone doping test results. The hydrolysis and bioactivation of testosterone enanthate is also genetically variable yielding a 2–3 fold variation in excretion rate and serum concentration, thereby implicating a substantial variation in ‘efficacy’ of testosterone. Given this situation it is logical to adopt the new findings in the doping control programme. The population based cut-off level for the testosterone : epitestosterone ratio should be replaced by a Bayesian interpretation of consecutive tests in the same individual. When combined with the above genetic information the sensitivity of the test is considerably improved. The combination of the three approaches should reduce the rate of falsely negative or positive results and the number of expensive follow-up tests, stipulated by the World Anti-Doping Agency. PMID:22506612

  7. Biomechanical comparison between lumbar disc arthroplasty and fusion.

    PubMed

    Chen, Shih-Hao; Zhong, Zheng-Cheng; Chen, Chen-Sheng; Chen, Wen-Jer; Hung, Chinghua

    2009-03-01

    The artificial disc is a mobile implant for degenerative disc replacement that attempts to lessen the degeneration of the adjacent elements. However, inconsistent biomechanical results for the neighboring elements have been reported in a number of studies. The present study used finite element (FE) analysis to explore the biomechanical differences at the surgical and both adjacent levels following artificial disc replacement and interbody fusion procedures. First, a three-dimensional FE model of a five-level lumbar spine was established by the commercially available medical imaging software Amira 3.1.1, and FE software ANSYS 9.0. After validating the five-level intact (INT) model with previous in vitro studies, the L3/L4 level of the INT model was modified to either insert an artificial disc (ProDisc II; ADR) or incorporate bilateral posterior lumbar interbody fusion (PLIF) cages with a pedicle screw fixation system. All models were constrained at the bottom of the L5 vertebra and subjected to 150N preload and 10Nm moments under four physiological motions. The ADR model demonstrated higher range of motion (ROM), annulus stress, and facet contact pressure at the surgical level compared to the non-modified INT model. At both adjacent levels, ROM and annulus stress were similar to that of the INT model and varied less than 7%. In addition, the greatest displacement of posterior annulus occurred at the superior-lateral region. Conversely, the PLIF model showed less ROM, less annulus stress, and no facet contact pressure at the surgical level compared to the INT model. The adjacent levels had obviously high ROM, annulus stress, and facet contact pressure, especially at the adjacent L2/3 level. In conclusion, the artificial disc replacement revealed no adjacent-level instability. However, instability was found at the surgical level, which might accelerate degeneration at the highly stressed annulus and facet joint. In contrast to disc replacement results, the posterior

  8. Biologic Treatment of Mild and Moderate Intervertebral Disc Degeneration

    PubMed Central

    Vasiliadis, Elias S; Pneumaticos, Spyros G; Evangelopoulos, Demitrios S; Papavassiliou, Athanasios G

    2014-01-01

    Disc degeneration is the most common cause of back pain in adults and has enormous socioeconomic implications. Conservative management is ineffective in most cases, and results of surgical treatment have not yet reached desirable standards. Biologic treatment options are an alternative to the above conventional management and have become very attractive in recent years. The present review highlights the currently available biologic treatment options in mild and moderate disc degeneration, where a potential for regeneration still exists. Biologic treatment options include protein-based and cell-based therapies. Protein-based therapies involve administration of biologic factors into the intervertebral disc to enhance matrix synthesis, delay degeneration or impede inflammation. These factors can be delivered by an intradiscal injection, alone or in combination with cells or tissue scaffolds and by gene therapy. Cell-based therapies comprise treatment strategies that aim to either replace necrotic or apoptotic cells, or minimize cell death. Cell-based therapies are more appropriate in moderate stages of degenerated disc disease, when cell population is diminished; therefore, the effect of administration of growth factors would be insufficient. Although clinical application of biologic treatments is far from being an everyday practice, the existing studies demonstrate promising results that will allow the future design of more sophisticated methods of biologic intervention to treat intervertebral disc degeneration. PMID:25171110

  9. Cervical Total Disc Arthroplasty

    PubMed Central

    Basho, Rahul; Hood, Kenneth A.

    2012-01-01

    Symptomatic adjacent segment degeneration of the cervical spine remains problematic for patients and surgeons alike. Despite advances in surgical techniques and instrumentation, the solution remains elusive. Spurred by the success of total joint arthroplasty in hips and knees, surgeons and industry have turned to motion preservation devices in the cervical spine. By preserving motion at the diseased level, the hope is that adjacent segment degeneration can be prevented. Multiple cervical disc arthroplasty devices have come onto the market and completed Food and Drug Administration Investigational Device Exemption trials. Though some of the early results demonstrate equivalency of arthroplasty to fusion, compelling evidence of benefits in terms of symptomatic adjacent segment degeneration are lacking. In addition, non-industry-sponsored studies indicate that these devices are equivalent to fusion in terms of adjacent segment degeneration. Longer-term studies will eventually provide the definitive answer. PMID:24353955

  10. Avoiding legal pitfalls in surrogacy arrangements.

    PubMed

    James, Summer; Chilvers, Rebecca; Havemann, Dara; Phelps, John Y

    2010-12-01

    The goal of this article is to discuss the legal pitfalls that reproductive endocrinologists face when participating in gestational surrogacy contracts. This paper was composed using Westlaw and LexisNexis commercial legal search engines to perform a review of statutes and cases pertaining to gestational surrogacy. The search results demonstrated that in the absence of suitable preparation, there is significant potential for litigation while participating in gestational agreements. Providers caring for gestational carriers have been named as parties in lawsuits for failure to provide psychological screening, failure to screen for infectious disease and participation in gestational contracts that are not compliant with state law. There is great disparity in state laws and court rulings pertaining to gestational agreements. When legal disputes arise, individual state laws and court rulings are controlling over the Uniform Parentage Act. Likewise, recommendations by the American College of Obstetricians and Gynecologists and the American Society for Reproductive Medicine do not supersede state laws. The failure to abide by individual state laws unnecessarily exposes reproductive endocrinologists and their IVF facilities to potential litigation. In order to lessen exposure to litigation, an understanding of individual state legislation or historical court rulings is advised. PMID:21050815

  11. Avoiding numerical pitfalls in social force models

    NASA Astrophysics Data System (ADS)

    Köster, Gerta; Treml, Franz; Gödel, Marion

    2013-06-01

    The social force model of Helbing and Molnár is one of the best known approaches to simulate pedestrian motion, a collective phenomenon with nonlinear dynamics. It is based on the idea that the Newtonian laws of motion mostly carry over to pedestrian motion so that human trajectories can be computed by solving a set of ordinary differential equations for velocity and acceleration. The beauty and simplicity of this ansatz are strong reasons for its wide spread. However, the numerical implementation is not without pitfalls. Oscillations, collisions, and instabilities occur even for very small step sizes. Classic solution ideas from molecular dynamics do not apply to the problem because the system is not Hamiltonian despite its source of inspiration. Looking at the model through the eyes of a mathematician, however, we realize that the right hand side of the differential equation is nondifferentiable and even discontinuous at critical locations. This produces undesirable behavior in the exact solution and, at best, severe loss of accuracy in efficient numerical schemes even in short range simulations. We suggest a very simple mollified version of the social force model that conserves the desired dynamic properties of the original many-body system but elegantly and cost efficiently resolves several of the issues concerning stability and numerical resolution.

  12. Setting dietary intake levels: problems and pitfalls.

    PubMed

    Russell, Robert M

    2007-01-01

    Recommended dietary intake levels are the nutrient standards used in designing food assistance programmes, institutional feeding programmes, counselling and teaching. In the USA, the recommended dietary allowances (RDAs) are the basis for setting the poverty threshold and food stamp allotments. In the 1990s, a new paradigm was put forth for estimating nutrient requirements and recommended intake levels. This considered the level of nutrient needed for normal body functioning (versus the amount needed to prevent a deficiency state from occurring). An estimated average requirement (EAR), an RDA and a tolerable upper intake level (UL) were determined for most nutrients. In setting forth these nutrient intake levels (dietary reference intakes, DRIs), a number of data challenges were encountered. For example, it was recognized that for most nutrients there was an absence of dose-response data, and few chronic human or animal studies had been undertaken. In considering how to revise nutrient intake recommendations for populations in the future, the following pitfalls must be overcome: (1) invalid assumption that a threshold level for a requirement will hold for all nutrients; (2) lack of uniform criteria for the selection of the endpoints used (need for evidence-based review, consideration of comparative risk); (3) invalid extrapolations to children for many nutrients; (4) lack of information on variability of responses, and interactions with other nutrients; and (5) lack of understanding in the community of how to use the various DRI numbers. PMID:17913222

  13. Pitfalls in PET/CT imaging

    NASA Astrophysics Data System (ADS)

    Rondogianni, Ph; Papathanasiou, N.; Giannopoulou, Ch

    2011-09-01

    PET with 2-[fluorine 18] fluoro-2-deoxy-d-glucose (FDG), has been a clinical tool for the evaluation of various cancers providing valuable metabolic information clinically helpful in the diagnosis, initial staging, therapy monitoring and restaging. However, FDG is not specific for neoplastic processes. Unless anatomic correlation is available to delineate normal structures, pathologic sites of FDG accumulation can easily be confused with normal physiological uptake, leading to false-positive or false-negative findings. Coregistration of PET scans (functional and morphologic information) with computed tomographic (CT) scans (anatomic information) using a combined PET-CT scanner improves the overall sensitivity and specificity of information provided by PET or CT alone. In this paper, we discuss the probable causes of false negative images and pitfalls due to technical reasons, inflammatory processes or benign lesions as well as the utility of PET-CT in differentiating malignant from inflammatory and benign processes, since in some cases such differentiation cannot be made, with certainty, using FDG PET alone.

  14. Core biopsies of the breast: diagnostic pitfalls.

    PubMed

    Joshi, Megha; Reddy, Sriharshan J; Nanavidekar, Manjiri; Russo, John P; Russo, Armand V; Pathak, Ram

    2011-01-01

    The incidence of breast cancer is increasing worldwide. In this review article, the authors compare and contrast the incidence of breast cancer, and the inherent differences in the United States (US) and India in screening techniques used for diagnosing breast cancer. In spite of these differences, core biopsies of the breast are common for diagnosis of breast cancer in both countries. The authors describe "Best Practices" in the reporting and processing of core biopsies and in the analysis of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor Receptor 2 (Her2/neu). The pitfalls in the diagnosis of fibroepithelial lesions of the breast on core biopsy are discussed, as also the significance of pseudoangiomatous stromal hyperplasia of the breast (PASH) is discussed in core biopsy. In this review, the management and diagnosis of flat epithelial atypia and radiation atypia are elaborated and the use of immunohistochemistry (IHC) in papillary lesions, phyllodes tumor, and complex sclerosing lesions (radial scars) is illustrated. Rarer lesions such as mucinous and histiocytoid carcinoma are also discussed. PMID:22234089

  15. Esophageal Impedance Monitoring: Clinical Pearls and Pitfalls.

    PubMed

    Ravi, Karthik; Katzka, David A

    2016-09-01

    The development of intraluminal esophageal impedance monitoring has improved our ability to detect and measure gastroesophageal reflux without dependence on acid content. This ability to detect previously unrecognized weak or nonacid reflux episodes has had important clinical implications in the diagnosis and management of gastroesophageal reflux disease (GERD). In addition, with the ability to assess bolus transit within the esophageal lumen, impedance monitoring has enhanced the recognition and characterization of esophageal motility disorders in patients with nonobstructive dysphagia. The assessment of the intraluminal movement of gas and liquid has also been proven to be of diagnostic value in conditions such as rumination syndrome and excessive belching. Further, alternative applications of impedance monitoring, such as the measurement of mucosal impedance, have provided novel insights into assessing esophageal mucosal integrity changes as a consequence of inflammatory change. Future applications for esophageal impedance monitoring also hold promise in esophageal conditions other than GERD. However, despite all of the clinical benefits afforded by esophageal impedance monitoring, important clinical and technical shortcomings limit its diagnostic value and must be considered when interpreting study results. Overinterpretation of studies or application of impedance monitoring in patients can have deleterious clinical implications. This review will highlight the clinical benefits and limitations of esophageal impedance monitoring and provide clinical pearls and pitfalls associated with this technology. PMID:27325223

  16. Avoiding numerical pitfalls in social force models.

    PubMed

    Köster, Gerta; Treml, Franz; Gödel, Marion

    2013-06-01

    The social force model of Helbing and Molnár is one of the best known approaches to simulate pedestrian motion, a collective phenomenon with nonlinear dynamics. It is based on the idea that the Newtonian laws of motion mostly carry over to pedestrian motion so that human trajectories can be computed by solving a set of ordinary differential equations for velocity and acceleration. The beauty and simplicity of this ansatz are strong reasons for its wide spread. However, the numerical implementation is not without pitfalls. Oscillations, collisions, and instabilities occur even for very small step sizes. Classic solution ideas from molecular dynamics do not apply to the problem because the system is not Hamiltonian despite its source of inspiration. Looking at the model through the eyes of a mathematician, however, we realize that the right hand side of the differential equation is nondifferentiable and even discontinuous at critical locations. This produces undesirable behavior in the exact solution and, at best, severe loss of accuracy in efficient numerical schemes even in short range simulations. We suggest a very simple mollified version of the social force model that conserves the desired dynamic properties of the original many-body system but elegantly and cost efficiently resolves several of the issues concerning stability and numerical resolution. PMID:23848804

  17. Principles and pitfalls of nerve conduction studies.

    PubMed

    Kimura, J

    1984-10-01

    This report reviews the fundamental principles and the changing concepts of nerve stimulation techniques, and discusses the proper application of these techniques in the differential diagnosis of peripheral nerve disorders. Nerve conduction studies help delineate the extent and distribution of the neural lesion and distinguish two major categories of peripheral nerve disease: demyelination and axonal degeneration. Although the method is based on simple principles, pitfalls abound in practice. Variability in nerve conduction measurement may result from temperature change, variations among nerve segments, and the effects of age. Other sources of error include excessive spread of stimulation current, anomalous innervation, temporal dispersion, and inaccuracy of surface measurement. Unlike a bipolar derivation, which selectively records near-field potentials, a referential recording may give rise to stationary far-field peaks from a moving source. Overlooking this possibility can lead to an incorrect interpretation of findings. Conventional nerve conduction studies deal primarily with measurements of the distal nerve segments in an extremity. More recent techniques are applicable to less accessible anatomical regions, as illustrated by elicitation of the blink reflex, F wave, and H reflex, and the use of the inching technique. Other methods used to assess special aspects of nerve conduction include the ischemic test and studies of slow-conducting fibers. PMID:6093680

  18. Indications for full prosthetic disc arthroplasty: a correlation of clinical outcome against a variety of indications.

    PubMed

    Bertagnoli, Rudolf; Kumar, Selva

    2002-10-01

    In this prospective study, a total of 134 prosthetic discs were replaced in 108 patients undergoing total disc replacement surgeries for degenerative disc disease. It was the aim of this study to correlate the clinical findings and the outcome of our patients treated with Prodisc II prostheses for various indications and to formulate indication criteria for disc replacement surgeries. The discs were implanted at L5/S1 in 61 patients, L5/L6 in 3 patients, L4/L5 in 31 patients, L3/L4 in 7 patients, and L2/L3 in 3 patients. There were 12 patients with two-level implants: from L4 to S1 in 11 of them and from L2 to L5 in the remaining one. Two patients also had three-level implants, from L3 to S1. Follow-up evaluation included plain radiographs, physical evaluation, and subjective evaluation by the patient using the Oswestry scale, the visual analog pain scale, and the SF-36V2 well-being questionnaire. The evaluation exercise showed that 90.8% of patients had excellent results, 7.4% had good results and 1.8% had fair results, with no poor results seen. Postoperatively, the average vertebral motion was increased in all patients at the operated level. Progression of disc degeneration at the adjacent levels was noted in ten patients. The average time to resuming activities of daily living unaided was 2.3 weeks. No implant failures or complications due to surgery were encountered in this study. Total prosthesis disc replacement for degenerative disc disease was found to be a good treatment modality, provided proper patient selection and criteria are adhered to. We were able to formulate indication criteria based on this. PMID:12384734

  19. Double-disc gate valve

    DOEpatents

    Wheatley, Seth J.

    1979-01-01

    This invention relates to an improvement in a conventional double-disc gate valve having a vertically movable gate assembly including a wedge, spreaders slidably engaged therewtih, a valve disc carried by the spreaders. When the gate assembly is lowered to a selected point in the valve casing, the valve discs are moved transversely outward to close inlet and outlet ports in the casing. The valve includes hold-down means for guiding the disc-and-spreader assemblies as they are moved transversely outward and inward. If such valves are operated at relatively high differential pressures, they sometimes jam during opening. Such jamming has been a problem for many years in gate valves used in gaseous diffusion plants for the separtion of uranium isotopes. The invention is based on the finding that the above-mentioned jamming results when the outlet disc tilts about its horizontal axis in a certain way during opening of the valve. In accordance with the invention, tilting of the outlet disc is maintained at a tolerable value by providing the disc with a rigid downwardly extending member and by providing the casing with a stop for limiting inward arcuate movement of the member to a preselected value during opening of the valve.

  20. Discs in misaligned binary systems

    NASA Astrophysics Data System (ADS)

    Rawiraswattana, Krisada; Hubber, David A.; Goodwin, Simon P.

    2016-08-01

    We perform SPH simulations to study precession and changes in alignment between the circumprimary disc and the binary orbit in misaligned binary systems. We find that the precession process can be described by the rigid-disc approximation, where the disc is considered as a rigid body interacting with the binary companion only gravitationally. Precession also causes change in alignment between the rotational axis of the disc and the spin axis of the primary star. This type of alignment is of great important for explaining the origin of spin-orbit misaligned planetary systems. However, we find that the rigid-disc approximation fails to describe changes in alignment between the disc and the binary orbit. This is because the alignment process is a consequence of interactions that involve the fluidity of the disc, such as the tidal interaction and the encounter interaction. Furthermore, simulation results show that there are not only alignment processes, which bring the components towards alignment, but also anti-alignment processes, which tend to misalign the components. The alignment process dominates in systems with misalignment angle near 90°, while the anti-alignment process dominates in systems with the misalignment angle near 0° or 180°. This means that highly misaligned systems will become more aligned but slightly misaligned systems will become more misaligned.

  1. Medical Information on Optical Disc*

    PubMed Central

    Schipma, Peter B.; Cichocki, Edward M.; Ziemer, Susan M.

    1987-01-01

    Optical discs may permit a revolutionary change in the distribution and use of medical information. A single compact disc, similar in size to that used for digital audio recording, can contain over 500 million characters of information that is accessible by a Personal Computer. These discs can be manufactured at a cost lower than that of print on paper, at reasonable volumes. Software can provide the health care professional with nearly instantaneous access to the information. Thus, for the first time, the opportunity exists to have large local medical information collections. This paper describes an application of this technology in the field of Oncology.

  2. Revision of a Charité artificial disc 9.5 years in vivo to a new Charité artificial disc: case report and explant analysis.

    PubMed

    David, Thierry

    2005-06-01

    This report describes a case of one-level total disc replacement (TDR) of L5-S1 requiring revision at 9.5 years following the index surgery due to polyethylene failure caused by high oxidation. Primary revision strategies for TDR include instrumented posterolateral fusion, or 360 degrees fusion with replacement of the prosthesis with cages or allograft bone. A revision of a TDR with a similar prosthesis has not been described in the literature. An active 42-year-old female underwent TDR with a Charité artificial disc. She remained active and pain free for 9.5 years before presenting with moderate low-back pain and sciatica. Radiographic studies confirmed a fragmented polyethylene core. The failed prosthesis was revised to a new Charité disc with the patient again active and pain free for 6 months following surgery. Chemical and physical analysis of the core indicated high oxidation due to gamma sterilization in air; a process changed to gamma sterilization in nitrogen in 1998 to meet industry standards. No evidence of wear debris was noted. Revision of an artificial disc with an artificial disc can be performed safely and adequately with the Charité disc prosthesis as an alternative to fusion necessitated by a device failure. An anterior revision approach carries significant risk and should only be performed by surgeons experienced in anterior lumbar surgery. PMID:15672241

  3. Operative Management of Lumbar Degenerative Disc Disease.

    PubMed

    Lee, Yu Chao; Zotti, Mario Giuseppe Tedesco; Osti, Orso Lorenzo

    2016-08-01

    Lumbar degenerative disc disease is extremely common. Current evidence supports surgery in carefully selected patients who have failed non-operative treatment and do not exhibit any substantial psychosocial overlay. Fusion surgery employing the correct grafting and stabilization techniques has long-term results demonstrating successful clinical outcomes. However, the best approach for fusion remains debatable. There is some evidence supporting the more complex, technically demanding and higher risk interbody fusion techniques for the younger, active patients or patients with a higher risk of non-union. Lumbar disc arthroplasty and hybrid techniques are still relatively novel procedures despite promising short-term and mid-term outcomes. Long-term studies demonstrating superiority over fusion are required before these techniques may be recommended to replace fusion as the gold standard. Novel stem cell approaches combined with tissue engineering therapies continue to be developed in expectation of improving clinical outcomes. Results with appropriate follow-up are not yet available to indicate if such techniques are safe, cost-effective and reliable in the long-term. PMID:27559465

  4. Operative Management of Lumbar Degenerative Disc Disease

    PubMed Central

    Lee, Yu Chao; Osti, Orso Lorenzo

    2016-01-01

    Lumbar degenerative disc disease is extremely common. Current evidence supports surgery in carefully selected patients who have failed non-operative treatment and do not exhibit any substantial psychosocial overlay. Fusion surgery employing the correct grafting and stabilization techniques has long-term results demonstrating successful clinical outcomes. However, the best approach for fusion remains debatable. There is some evidence supporting the more complex, technically demanding and higher risk interbody fusion techniques for the younger, active patients or patients with a higher risk of non-union. Lumbar disc arthroplasty and hybrid techniques are still relatively novel procedures despite promising short-term and mid-term outcomes. Long-term studies demonstrating superiority over fusion are required before these techniques may be recommended to replace fusion as the gold standard. Novel stem cell approaches combined with tissue engineering therapies continue to be developed in expectation of improving clinical outcomes. Results with appropriate follow-up are not yet available to indicate if such techniques are safe, cost-effective and reliable in the long-term. PMID:27559465

  5. Decellularized allogeneic intervertebral disc: natural biomaterials for regenerating disc degeneration

    PubMed Central

    Hu, Zhijun; Chen, Kai; Shan, Zhi; Chen, Shuai; Wang, Jiying; Mo, Jian; Ma, Jianjun; Xu, Wenbing; Qin, An; Fan, Shunwu

    2016-01-01

    Intervertebral disc degeneration is associated with back pain and disc herniation. This study established a modified protocol for intervertebral disc (IVD) decellularization and prepared its extracellular matrix (ECM). By culturing mesenchymal stem cells (MSCs)(3, 7, 14 and 21 days) and human degenerative IVD cells (7 days) in the ECM, implanting it subcutaneously in rabbit and injecting ECM microparticles into degenerative disc, the biological safety and efficacy of decellularized IVD was evaluated both in vitro and in vivo. Here, we demonstrated that cellular components can be removed completely after decellularization and maximally retain the structure and biomechanics of native IVD. We revealed that allogeneic ECM did not evoke any apparent inflammatory reaction in vivo and no cytotoxicity was found in vitro. Moreover, IVD ECM can induce differentiation of MSCs into IVD-like cells in vitro. Furthermore, allogeneic ECM microparticles are effective on the treatment of rabbit disc degeneration in vivo. In conclusion, our study developed an optimized method for IVD decellularization and we proved decellularized IVD is safe and effective for the treatment of degenerated disc diseases. PMID:26933821

  6. Enlivening Physics, a Local Video Disc Project.

    ERIC Educational Resources Information Center

    McInerney, M.

    1989-01-01

    Describes how to make and use an inexpensive video disc of physics demonstrations. Discusses the background, production of the disc, subject of the disc including angular momentum, "monkey and the hunter" experiment, Doppler shift, pressure of a constant volume of gas thermometer, and wave effects, and using the disc in classroom. (YP)

  7. Disc Golf: Teaching a Lifetime Activity

    ERIC Educational Resources Information Center

    Eastham, Susan L.

    2015-01-01

    Disc golf is a lifetime activity that can be enjoyed by students of varying skill levels and abilities. Disc golf follows the principles of ball golf but is generally easier for students to play and enjoy success. The object of disc golf is similar to ball golf and involves throwing a disc from the teeing area to the target in as few throws as…

  8. Hip joint replacement

    MedlinePlus

    ... this page: //medlineplus.gov/ency/article/002975.htm Hip joint replacement To use the sharing features on this page, please enable JavaScript. Hip joint replacement is surgery to replace all or part ...

  9. Knee joint replacement

    MedlinePlus

    ... page: //medlineplus.gov/ency/article/002974.htm Knee joint replacement To use the sharing features on this page, please enable JavaScript. Knee joint replacement is a surgery to replace a knee ...

  10. Pitfalls and optimal approaches to diagnose melioidosis.

    PubMed

    Kingsley, Paul Vijay; Arunkumar, Govindakarnavar; Tipre, Meghan; Leader, Mark; Sathiakumar, Nalini

    2016-06-01

    Melioidosis is a severe and fatal infectious disease in the tropics and subtropics. It presents as a febrile illness with protean manifestation ranging from chronic localized infection to acute fulminant septicemia with dissemination of infection to multiple organs characterized by abscesses. Pneumonia is the most common clinical presentation. Because of the wide range of clinical presentations, physicians may often misdiagnose and mistreat the disease for tuberculosis, pneumonia or other pyogenic infections. The purpose of this paper is to present common pitfalls in diagnosis and provide optimal approaches to enable early diagnosis and prompt treatment of melioidosis. Melioidosis may occur beyond the boundaries of endemic areas. There is no pathognomonic feature specific to a diagnosis of melioidosis. In endemic areas, physicians need to expand the diagnostic work-up to include melioidosis when confronted with clinical scenarios of pyrexia of unknown origin, progressive pneumonia or sepsis. Radiological imaging is an integral part of the diagnostic workup. Knowledge of the modes of transmission and risk factors will add support in clinically suspected cases to initiate therapy. In situations of clinically highly probable or possible cases where laboratory bacteriological confirmation is not possible, applying evidence-based criteria and empirical treatment with antimicrobials is recommended. It is of prime importance that patients undergo the full course of antimicrobial therapy to avoid relapse and recurrence. Early diagnosis and appropriate management is crucial in reducing serious complications leading to high mortality, and in preventing recurrences of the disease. Thus, there is a crucial need for promoting awareness among physicians at all levels and for improved diagnostic microbiology services. Further, the need for making the disease notifiable and/or initiating melioidosis registries in endemic countries appears to be compelling. PMID:27262061

  11. Tissue engineering: A live disc

    NASA Astrophysics Data System (ADS)

    Hukins, David W. L.

    2005-12-01

    A material-cell hybrid device that mimics the anatomic shape of the intervertebral disc has been made and successfully implanted into mice to show that tissue engineering may, in the future, benefit sufferers from back pain.

  12. Disc Golf, a Growing Sport

    PubMed Central

    Nelson, Joseph T.; Jones, Richard E.; Runstrom, Michael; Hardy, Jolene

    2015-01-01

    Background Disc golf is a sport played much like traditional golf, but rather than using a ball and club, players throw flying discs with various throwing motions. It has been played by an estimated 8 to 12 million people in the United States. Like all sports, injuries sustained while playing disc golf are not uncommon. Although formalized in the 1970s, it has grown at a rapid pace; however, disc golf–related injuries have yet to be described in the medical literature. Purpose To describe the most common injuries incurred by disc golf players while comparing the different types of throwing styles. Study Design Descriptive epidemiology study. Methods The data in this study were collected from 883 disc golf players who responded to an online survey collected over a 1-month period. Respondents answered 49 questions related to demographics, experience, style of play, and injury details. Using a chi-square analysis, common injuries sustained in players using backhand and forehand throwing styles were compared. Results More than 81% of respondents stated that they had sustained an injury playing disc golf, including injuries to the elbow (n = 325), shoulder (n = 305), back (n = 218), and knee (n = 199). The injuries were most commonly described as a muscle strain (n = 241), sprain (n = 162), and tendinitis (n = 145). The type of throw primarily used by players varied, with 86.2% using backhand, 12.7% using forehand, and 1.1% using an overhead throw. Players using a forehand throw were more likely to sustain an elbow injury (P = .014). Many players (n = 115) stated they had undergone surgery due to a disc golf–related injury, with the most common surgeries including meniscal, shoulder, spine, and foot/ankle surgeries. Conclusion The majority of surveyed disc golfers sustained at least 1 injury while playing disc golf, with many requiring surgery. The types of injuries sustained by players varied by the types of throw primarily used. As the sport of disc golf continues

  13. Percutaneous diode laser disc nucleoplasty

    NASA Astrophysics Data System (ADS)

    Menchetti, P. P.; Longo, Leonardo

    2004-09-01

    The treatment of herniated disc disease (HNP) over the years involved different miniinvasive surgical options. The classical microsurgical approach has been substituted over the years both by endoscopic approach in which is possible to practice via endoscopy a laser thermo-discoplasty, both by percutaneous laser disc nucleoplasty. In the last ten years, the percutaneous laser disc nucleoplasty have been done worldwide in more than 40000 cases of HNP. Because water is the major component of the intervertebral disc, and in HNP pain is caused by the disc protrusion pressing against the nerve root, a 980 nm Diode laser introduced via a 22G needle under X-ray guidance and local anesthesia, vaporizes a small amount of nucleous polposus with a disc shrinkage and a relief of pressure on nerve root. Most patients get off the table pain free and are back to work in 5 to 7 days. Material and method: to date, 130 patients (155 cases) suffering for relevant symptoms therapy-resistant 6 months on average before consulting our department, have been treated. Eightyfour (72%) males and 46 (28%) females had a percutaneous laser disc nucleoplasty. The average age of patients operated was 48 years (22 - 69). The level of disc removal was L3/L4 in 12 cases, L4/L5 in 87 cases and L5/S1 in 56 cases. Two different levels were treated at the same time in 25 patients. Results: the success rate at a minimum follow-up of 6 months was 88% with a complication rate of 0.5%.

  14. Disc piezoelectric ceramic transformers.

    PubMed

    Erhart, Jirií; Půlpán, Petr; Doleček, Roman; Psota, Pavel; Lédl, Vít

    2013-08-01

    In this contribution, we present our study on disc-shaped and homogeneously poled piezoelectric ceramic transformers working in planar-extensional vibration modes. Transformers are designed with electrodes divided into wedge, axisymmetrical ring-dot, moonie, smile, or yin-yang segments. Transformation ratio, efficiency, and input and output impedances were measured for low-power signals. Transformer efficiency and transformation ratio were measured as a function of frequency and impedance load in the secondary circuit. Optimum impedance for the maximum efficiency has been found. Maximum efficiency and no-load transformation ratio can reach almost 100% and 52 for the fundamental resonance of ring-dot transformers and 98% and 67 for the second resonance of 2-segment wedge transformers. Maximum efficiency was reached at optimum impedance, which is in the range from 500 Ω to 10 kΩ, depending on the electrode pattern and size. Fundamental vibration mode and its overtones were further studied using frequency-modulated digital holographic interferometry and by the finite element method. Complementary information has been obtained by the infrared camera visualization of surface temperature profiles at higher driving power. PMID:25004532

  15. An Analysis of Burst Disc Pressure Instability

    SciTech Connect

    S. L. Robinson; B. C. Odegard, Jr.; N. r. Moody; S. H. Goods

    2000-06-01

    During the development stage of the 1X Acorn burst disc, burst pressure test results exhibited an unexpected increase of 8 to 14% over times of 90--100 days from initial fabrication. This increase is a concern where design constraints require stability. The disc material, 316L stainless steel sheet, is formed to a dome-like geometry and scored to produce a thin-walled, high-strength ligament. The fracture events controlling burst occur in that ligament. Thus it has been characterized both for tensile properties and microstructure through nanoindentation, magnetic measurements, optical and transmission electron microscopy. These results compare favorably with finite element simulation of the properties of the ligament. The ligament exhibits a highly heterogeneous microstructure; its small volume and microstructural heterogeneity make it difficult to identify which microstructural feature controls fracture and hence burst pressure. Bulk mechanical test specimens were fabricated to emulate mid-ligament properties, and aged at both room and elevated temperatures to characterize and accelerate the temporal behavior of the burst disc. Property changes included yield and ultimate tensile strength increases, and fracture strain decreases with aging. Specimens were subjected to a reversion anneal identical to that given the burst disc to eliminate the martensite phase formed during rolling. Reversion-annealed samples exhibited no change in properties in room temperature or accelerated aging, showing that the reversion-anneal eliminated the aging phenomenon. Aging was analyzed in terms of diffusion controlled precipitate growth kinetics, showing that carbon migration to dislocations is consistent with the strength increases. A vacancy-assisted diffusion mechanism for carbon transport is proposed, giving rise to rapid aging, which replaces interstitial carbon diffusion until excess vacancies from deformation are consumed. Mechanical activation parameters in stress relaxation

  16. How to avoid the ten most frequent EMS pitfalls

    SciTech Connect

    Andrews, W.

    1982-04-19

    It pays to do your homework before investing in an energy management system if you want to avoid the 10 most common pitfalls listed by users, consultants, and manufacturers as: oversimplification, improper maintenance, failure to involve operating personnel, inaccurate savings estimates, failure to include monitoring capability, incompetent or fradulent firms, improper load control, not allowing for a de-bugging period, failure to include manual override, and software problems. The article describes how each of these pitfalls can lead to poor decisions and poor results. (DCK)

  17. MRI Evaluation of Lumbar Disc Degenerative Disease

    PubMed Central

    Patel, Rupal; Mehta, Chetan; Patel, Narrotam

    2015-01-01

    Introduction: Lower back pain secondary to degenerative disc disease is a condition that affects young to middle-aged persons with peak incidence at approximately 40 y. MRI is the standard imaging modality for detecting disc pathology due to its advantage of lack of radiation, multiplanar imaging capability, excellent spinal soft-tissue contrast and precise localization of intervertebral discs changes. Aims and Objective: To evaluate the characterization, extent, and changes associated with the degenerative lumbar disc disease by Magnetic Resonance Imaging. Study Design: Cross-sectional and observational study. Materials and Methods: A total 109 patients of the lumbar disc degeneration with age group between 17 to 80 y were diagnosed & studied on 1.5 Tesla Magnetic Resonance Imaging machine. MRI findings like lumbar lordosis, Schmorl’s nodes, decreased disc height, disc annular tear, disc herniation, disc bulge, disc protrusion and disc extrusion were observed. Narrowing of the spinal canal, lateral recess and neural foramen with compression of nerve roots observed. Ligamentum flavum thickening and facetal arthropathy was observed. Result: Males were more commonly affected in Degenerative Spinal Disease & most of the patients show loss of lumbar lordosis. Decreased disc height was common at L5-S1 level. More than one disc involvement was seen per person. L4 – L5 disc was the most commonly involved. Annular disc tear, disc herniation, disc extrusion, narrowing of spinal canal, narrowing of lateral recess, compression of neural foramen, ligamentum flavum thickening and facetal arthropathy was common at the L4 –L5 disc level. Disc buldge was common at L3 – L4 & L4 – L5 disc level. Posterior osteophytes are common at L3 - L4 & L5 –S1 disc level. L1- L2 disc involvement and spondylolisthesis are less common. Conclusion: Lumbar disc degeneration is the most common cause of low back pain. Plain radiograph can be helpful in visualizing gross anatomic changes in

  18. Polarimetric Models of Circumstellar Discs Including Aggregate Dust Grains

    NASA Astrophysics Data System (ADS)

    Mohan, Mahesh

    The work conducted in this thesis examines the nature of circumstellar discs by investigating irradiance and polarization of scattered light. Two circumstellar discs are investigated. Firstly, H-band high contrast imaging data on the transitional disc of the Herbig Ae/Be star HD169142 are presented. The images were obtained through the polarimetric differential imaging (PDI) technique on the Very Large Telescope (VLT) using the adaptive optics system NACO. Our observations use longer exposure times, allowing us to examine the edges of the disc. Analysis of the observations shows distinct signs of polarization due to circumstellar material, but due to excessive saturation and adaptive optics errors further information on the disc could not be inferred. The HD169142 disc is then modelled using the 3D radiative transfer code Hyperion. Initial models were constructed using a two disc structure, however recent PDI has shown the existence of an annular gap. In addition to this the annular gap is found not to be devoid of dust. This then led to the construction of a four-component disc structure. Estimates of the mass of dust in the gap (2.10E-6 Msun) are made as well as for the planet (1.53E-5 Msun (0.016 Mjupiter)) suspected to be responsible for causing the gap. The predicted polarization was also estimated for the disc, peaking at ~14 percent. The use of realistic dust grains (ballistic aggregate particles) in Monte Carlo code is also examined. The fortran code DDSCAT is used to calculate the scattering properties for aggregates which are used to replace the spherical grain models used by the radiative transfer code Hyperion. Currently, Hyperion uses four independent elements to define the scattering matrix, therefore the use of rotational averaging and a 50/50 percent population of grains and their enantiomers were explored to reduce the number of contributing scattering elements from DDSCAT. A python script was created to extract the scattering data from the DDSCAT

  19. Pitfalls in statistical landslide susceptibility modelling

    NASA Astrophysics Data System (ADS)

    Schröder, Boris; Vorpahl, Peter; Märker, Michael; Elsenbeer, Helmut

    2010-05-01

    The use of statistical methods is a well-established approach to predict landslide occurrence probabilities and to assess landslide susceptibility. This is achieved by applying statistical methods relating historical landslide inventories to topographic indices as predictor variables. In our contribution, we compare several new and powerful methods developed in machine learning and well-established in landscape ecology and macroecology for predicting the distribution of shallow landslides in tropical mountain rainforests in southern Ecuador (among others: boosted regression trees, multivariate adaptive regression splines, maximum entropy). Although these methods are powerful, we think it is necessary to follow a basic set of guidelines to avoid some pitfalls regarding data sampling, predictor selection, and model quality assessment, especially if a comparison of different models is contemplated. We therefore suggest to apply a novel toolbox to evaluate approaches to the statistical modelling of landslide susceptibility. Additionally, we propose some methods to open the "black box" as an inherent part of machine learning methods in order to achieve further explanatory insights into preparatory factors that control landslides. Sampling of training data should be guided by hypotheses regarding processes that lead to slope failure taking into account their respective spatial scales. This approach leads to the selection of a set of candidate predictor variables considered on adequate spatial scales. This set should be checked for multicollinearity in order to facilitate model response curve interpretation. Model quality assesses how well a model is able to reproduce independent observations of its response variable. This includes criteria to evaluate different aspects of model performance, i.e. model discrimination, model calibration, and model refinement. In order to assess a possible violation of the assumption of independency in the training samples or a possible

  20. Acute trauma induced disc displacement without reduction and its sequelae.

    PubMed

    He, DongMei; Yang, XiuJuan; Wang, FeiYu; Yang, Chi; Dong, MinJun

    2016-01-01

    Acute traumatic temporomandibular joint disc displacement (ATDD) and its sequelae are not familiar for most surgeons. This study is to discuss its sequelae in cases without disc reduction after failed conservative treatment. From 2010 to 2015, 26 patients with 34 joints were included in the study. All patients had at least 3 months conservative treatment. Their maximal incisor opening (MIO) was measured during follow-ups and MRI examination was used to check the condylar bone degeneration. The mean follow-up for conservative treatment after admission was 8.69 months, the patients reached an average of 25.7 mm MIO. MRI showed condylar bone intact in 8 joints (23.5%), condylar surface bone destruction (Wilks IV, V stages) in 14 joints (41.2%), and severe bone resorption in 12 joints (35.3%). 15 patients with 23 joints were asked for surgical treatment after a mean conservative treatment of 5.4 months (3-12 months) to improve mouth opening and relieve chronic pain. 12 joints had total joint replacement (TJR). 11 joints had disc repositioning. Their mean MIO before operation was 19.8 mm and significantly improved to 33.9 mm after operation (p = 0.0000). ATDD may cause severe osteoarthritis or ankylosis. Disc repositioning and TJR could significantly improve MIO. PMID:27582054

  1. Biological treatment strategies for disc degeneration: potentials and shortcomings

    PubMed Central

    Nerlich, Andreas G.; Boos, Norbert

    2006-01-01

    Recent advances in molecular biology, cell biology and material sciences have opened a new emerging field of techniques for the treatment of musculoskeletal disorders. These new treatment modalities aim for biological repair of the affected tissues by introducing cell-based tissue replacements, genetic modifications of resident cells or a combination thereof. So far, these techniques have been successfully applied to various tissues such as bone and cartilage. However, application of these treatment modalities to cure intervertebral disc degeneration is in its very early stages and mostly limited to experimental studies in vitro or in animal studies. We will discuss the potential and possible shortcomings of current approaches to biologically cure disc degeneration by gene therapy or tissue engineering. Despite the increasing number of studies examining the therapeutic potential of biological treatment strategies, a practicable solution to routinely cure disc degeneration might not be available in the near future. However, knowledge gained from these attempts might be applied in a foreseeable future to cure the low back pain that often accompanies disc degeneration and therefore be beneficial for the patient. PMID:16983559

  2. Acute trauma induced disc displacement without reduction and its sequelae

    PubMed Central

    He, DongMei; Yang, XiuJuan; Wang, FeiYu; Yang, Chi; Dong, MinJun

    2016-01-01

    Acute traumatic temporomandibular joint disc displacement (ATDD) and its sequelae are not familiar for most surgeons. This study is to discuss its sequelae in cases without disc reduction after failed conservative treatment. From 2010 to 2015, 26 patients with 34 joints were included in the study. All patients had at least 3 months conservative treatment. Their maximal incisor opening (MIO) was measured during follow-ups and MRI examination was used to check the condylar bone degeneration. The mean follow-up for conservative treatment after admission was 8.69 months, the patients reached an average of 25.7 mm MIO. MRI showed condylar bone intact in 8 joints (23.5%), condylar surface bone destruction (Wilks IV, V stages) in 14 joints (41.2%), and severe bone resorption in 12 joints (35.3%). 15 patients with 23 joints were asked for surgical treatment after a mean conservative treatment of 5.4 months (3–12 months) to improve mouth opening and relieve chronic pain. 12 joints had total joint replacement (TJR). 11 joints had disc repositioning. Their mean MIO before operation was 19.8 mm and significantly improved to 33.9 mm after operation (p = 0.0000). ATDD may cause severe osteoarthritis or ankylosis. Disc repositioning and TJR could significantly improve MIO. PMID:27582054

  3. Role of biomechanics on intervertebral disc degeneration and regenerative therapies: What needs repairing in the disc and what are promising biomaterials for its repair?

    PubMed Central

    Iatridis, James C.; Nicoll, Steven B.; Michalek, Arthur J.; Walter, Benjamin A.; Gupta, Michelle S.

    2013-01-01

    Background Context Degeneration and injuries of the intervertebral disc result in large alterations in biomechanical behaviors. Repair strategies using biomaterials can be optimized based on biomechanical and biological requirements. Purpose To review current literature on 1) effects of degeneration, simulated degeneration, and injury on biomechanics of the intervertebral disc with special attention paid to needle puncture injuries which are a pathway for diagnostics and regenerative therapies; and 2) promising biomaterials for disc repair with a focus on how those biomaterials may promote biomechanical repair. Study Design/Setting A narrative review to evaluate the role of biomechanics on disc degeneration and regenerative therapies with a focus on what biomechanical properties need to be repaired and how to evaluate and accomplish such repairs using biomaterials. Model systems for screening of such repair strategies are also briefly described. Methods Papers were selected from two main Pubmed searches using keywords: intervertebral AND biomechanics (1823 articles) and intervertebral AND biomaterials (361 articles). Additional keywords (injury, needle puncture, nucleus pressurization, biomaterials, hydrogel, sealant, tissue engineering) were used to narrow articles to the topics most relevant to this review. Results Degeneration and acute disc injuries have the capacity to influence nucleus pulposus pressurization and annulus fibrosus integrity, which are necessary for effective disc function, and therefore, require repair. Needle injection injuries are of particular clinical relevance with potential to influence disc biomechanics, cellularity, and metabolism, yet these effects are localized or small, and more research is required to evaluate and reduce potential clinical morbidity using such techniques. NP replacement strategies, such as hydrogels, are required to restore NP pressurization or lost volume. AF repair strategies, including crosslinked hydrogels

  4. A comparison of pitfall traps with bait traps for studying leaf litter ant communities.

    PubMed

    Wang, C; Strazanac, J; Butler, L

    2001-06-01

    A comparison of pitfall traps with bait traps for sampling leaf litter ants was studied in oak-dominated mixed forests during 1995-1997. A total of 31,732 ants were collected from pitfall traps and 54,694 ants were collected from bait traps. They belonged to four subfamilies, 17 genera, and 32 species. Bait traps caught 29 species, whereas pitfall traps caught 31 species. Bait traps attracted one species not found in pitfall traps, but missed three of the species collected with pitfall traps. Collections from the two sampling methods showed differences in species richness, relative abundance, diversity, and species accumulation curves. Pitfall traps caught significantly more ant species per plot than did bait traps. The ant species diversity obtained from pitfall traps was higher than that from bait traps. Bait traps took a much longer time to complete an estimate of species richness than did pitfall traps. Little information was added to pitfall trapping results by the bait trapping method. The results suggested that the pitfall trapping method is superior to the bait trapping method for leaf litter ant studies. Species accumulation curves showed that sampling of 2,192+/-532 ants from six plots by pitfall traps provided a good estimation of ant species richness under the conditions of this study. PMID:11425034

  5. Pitfalls and Limitations of Radionuclide Imaging in Endocrinology.

    PubMed

    Agrawal, Kanhaiyalal; Esmail, Abdulredha A H; Gnanasegaran, Gopinath; Navalkissoor, Shaunak; Mittal, Bhagwant Rai; Fogelman, Ignac

    2015-09-01

    Several different techniques, radiopharmaceuticals, and imaging modalities are commonly used in nuclear medicine for studies of endocrine organs. Nuclear medicine is used in the management of benign and malignant thyroid, parathyroid, and neuroendocrine disorders. Thus, it is essential to acknowledge pitfalls and the limitations of nuclear medicine imaging for accurate diagnosis and patient management. PMID:26278855

  6. Five pitfalls of work redesign in acute care.

    PubMed

    Seago, J A

    1997-10-01

    During work redesign in nursing units, five common pitfalls can emerge: moving too fast, failing to involve major stakeholders, discounting bargaining unit contracts, separating training classes and not defining desired outcomes. Suggestions on how to avoid these problems are given. PMID:9369723

  7. Proposal Pitfalls Plaguing Researchers: Can Technical Communicators Make a Difference?

    ERIC Educational Resources Information Center

    Lemanski, Steve

    2014-01-01

    The facts bear out that the odds are against most scientific researchers and scholars--especially those just starting out--in their attempts to win funding for their research projects through their grant proposals. In this article, the author takes a close look at some of the proposal-related problems and pitfalls that have historically challenged…

  8. REVIEW ARTICLE: EIT reconstruction algorithms: pitfalls, challenges and recent developments

    NASA Astrophysics Data System (ADS)

    Lionheart, William R. B.

    2004-02-01

    We review developments, issues and challenges in electrical impedance tomography (EIT) for the 4th Conference on Biomedical Applications of Electrical Impedance Tomography, held at Manchester in 2003. We focus on the necessity for three-dimensional data collection and reconstruction, efficient solution of the forward problem, and both present and future reconstruction algorithms. We also suggest common pitfalls or 'inverse crimes' to avoid.

  9. Cases on Global E-Learning Practices: Successes and Pitfalls

    ERIC Educational Resources Information Center

    Sharma, Ramesh C., Ed.; Mishra, Sanjaya, Ed.

    2007-01-01

    "Cases on Global E-Learning Practices: Successes and Pitfalls" looks into global practices of e-learning, examining the successes and failures of e-learning professionals. It provides a judicious mix of practical experiences and research in the form of case studies. Written by experts from all over the globe, this book shows how to design…

  10. E-Content Development for Languages: Success Factors and Pitfalls

    ERIC Educational Resources Information Center

    De Paepe, Liesbeth

    2014-01-01

    This paper discusses the success factors and pitfalls in development of e-content for languages. The factors discussed draw on several years of experience in developing and implementing 95% distance courses for Dutch as a second language in the adult education sector in Flanders and on PhD research at VUB. The CEFR [Common European Framework of…

  11. The Pitfalls and Triumphs of Launching a Charter School.

    ERIC Educational Resources Information Center

    Page, Linda; Levine, Mark

    1996-01-01

    A principal of a charter school in Colorado Springs, Colorado, recounts the triumphs and pitfalls of the school's first year. The school charter lacked a clear-cut avenue for making changes. Intending to create a parent-run school, the founding board (themselves parents) made drastic curricular changes without consulting other parents. Passionate…

  12. A photopolymerized composite hydrogel and surgical implanting tool for a nucleus pulposus replacement.

    PubMed

    Schmocker, Andreas; Khoushabi, Azadeh; Frauchiger, Daniela A; Gantenbein, Benjamin; Schizas, Constantin; Moser, Christophe; Bourban, Pierre-Etienne; Pioletti, Dominique P

    2016-05-01

    Nucleus pulposus replacements have been subjected to highly controversial discussions over the last 40 years. Their use has not yet resulted in a positive outcome to treat herniated disc or degenerated disc disease. The main reason is that not a single implant or tissue replacement was able to withstand the loads within an intervertebral disc. Here, we report on the development of a photo-polymerizable poly(ethylene glycol)dimethacrylate nano-fibrillated cellulose composite hydrogel which was tuned according to native tissue properties. Using a customized minimally-invasive medical device to inject and photopolymerize the hydrogel insitu, samples were implanted through an incision of 1 mm into an intervertebral disc of a bovine organ model to evaluate their long-term performance. When implanted into the bovine disc model, the composite hydrogel implant was able to significantly re-establish disc height after surgery (p < 0.0025). The height was maintained after 0.5 million loading cycles (p < 0.025). The mechanical resistance of the novel composite hydrogel material combined with the minimally invasive implantation procedure into a bovine disc resulted in a promising functional orthopedic implant for the replacement of the nucleus pulposus. PMID:26976264

  13. Chondrule transport in protoplanetary discs

    NASA Astrophysics Data System (ADS)

    Goldberg, Aaron Z.; Owen, James E.; Jacquet, Emmanuel

    2015-10-01

    Chondrule formation remains one of the most elusive early Solar system events. Here, we take the novel approach of employing numerical simulations to investigate chondrule origin beyond purely cosmochemical methods. We model the transport of generically produced chondrules and dust in a 1D viscous protoplanetary disc model in order to constrain the chondrule formation events. For a single formation event we are able to match analytical predictions of the memory they retain of each other (complementarity), finding that a large mass accretion rate (≳10-7 M⊙ yr-1) allows for delays on the order of the disc's viscous time-scale between chondrule formation and chondrite accretion. Further, we find older discs to be severely diminished of chondrules, with accretion rates ≲10-9 M⊙ yr-1 for nominal parameters. We then characterize the distribution of chondrule origins in both space and time, as functions of disc parameters and chondrule formation rates, in runs with continuous chondrule formation and both static and evolving discs. Our data suggest that these can account for the observed diversity between distinct chondrite classes, if some diversity in accretion time is allowed for.

  14. Gravitoturbulence in magnetized protostellar discs

    NASA Astrophysics Data System (ADS)

    Riols, A.; Latter, H.

    2016-08-01

    Gravitational instability (GI) features in several aspects of protostellar disc evolution, most notably in angular momentum transport, fragmentation, and the outbursts exemplified by FU Ori and EX Lupi systems. The outer regions of protostellar discs may also be coupled to magnetic fields, which could then modify the development of GI. To understand the basic elements of their interaction, we perform local 2D ideal and resistive magnetohydrodynamics simulations with an imposed toroidal field. In the regime of moderate plasma beta, we find that the system supports a hot gravitoturbulent state, characterized by considerable magnetic energy and stress and a surprisingly large Toomre parameter Q ≳ 10. This result has potential implications for disc structure, vertical thickness, ionization, etc. Our simulations also reveal the existence of long-lived and dense `magnetic islands' or plasmoids. Lastly, we find that the presence of a magnetic field has little impact on the fragmentation criterion of the disc. Though our focus is on protostellar discs, some of our results may be relevant for the outer radii of AGN.

  15. Biomechanical Characterization of an Annulus Sparing Spinal Disc Prosthesis

    PubMed Central

    Buttermann, Glenn R.; Beaubien, Brian P.

    2009-01-01

    Background Context Current spine arthroplasty devices, require disruption of the annulus fibrosus for implantation. Preliminary studies of a unique annulus sparing intervertebral prosthetic disc (IPD), found that preservation of the annulus resulted in load sharing of the annulus with the prosthesis. Purpose Determine flexibility of the IPD versus fusion constructs in normal and degenerated human spines. Study design/Setting Biomechanical comparison of motion segments in the intact, fusion and mechanical nucleus replacement states for normal and degenerated states. Patient setting Thirty lumbar motion segments. Outcomes Measures Intervertebral height; motion segment range-of-motion (ROM), neutral zone (NZ), stiffness. Methods Motion segments had multi-directional flexibility testing to 7.5 Nm for intact discs, discs reconstructed using the IPD (n=12), or after anterior/posterior fusions (n=18). Interbody height and axial compression stiffness changes were determined for the reconstructed discs by applying axial compression to 1500 N. Analysis included stratifying results to normal mobile vs. rigid degenerated intact motion segments. Results The mean interbody height increase was 1.5 mm for IPD reconstructed discs. vs 3.0 mm for fused segments. Axial compression stiffness was 3.0 ± 0.9 kN/mm for intact compared to 1.2 ± 0.4 kN/mm for IPD reconstructed segments. Reconstructed disc ROM was 9.0° ± 3.7° in flexion-extension, 10.6° ± 3.4° in lateral bending and 2.8° ± 1.4° in axial torsion which was similar to intact values and significantly greater than respective fusion values (p<0.001). Mobile intact segments exhibited significantly greater rotation after fusion vs. their more rigid counterparts (p<0.05), however, intact motion was not related to motion after IPD reconstruction. The NZ and rotational stiffness followed similar trends. Differences in NZ between mobile and rigid intact specimens tended to decrease in the IPD reconstructed state. Conclusion

  16. Wear analysis of disc cutters of full face rock tunnel boring machine

    NASA Astrophysics Data System (ADS)

    Zhang, Zhaohuang; Meng, Liang; Sun, Fei

    2014-11-01

    Wear is a major factor of disc cutters' failure. No current theory offers a standard for the prediction of disc cutter wear yet. In the field the wear prediction method commonly used is based on the excavation length of tunnel boring machine(TBM) to predict the disc cutter wear and its wear law, considering the location number of each disc cutter on the cutterhead(radius for installation); in theory, there is a prediction method of using arc wear coefficient. However, the preceding two methods have their own errors, with their accuracy being 40% or so and largely relying on the technicians' experience. Therefore, radial wear coefficient, axial wear coefficient and trajectory wear coefficient are defined on the basis of the operating characteristics of TBM. With reference to the installation and characteristics of disc cutters, those coefficients are modified according to penetration, which gives rise to the presentation of comprehensive axial wear coefficient, comprehensive radial wear coefficient and comprehensive trajectory wear coefficient. Calculation and determination of wear coefficients are made with consideration of data from a segment of TBM project(excavation length 173 m). The resulting wear coefficient values, after modification, are adopted to predict the disc cutter wear in the follow-up segment of the TBM project(excavation length of 5621 m). The prediction results show that the disc cutter wear predicted with comprehensive radial wear coefficient and comprehensive trajectory wear coefficient are not only accurate(accuracy 16.12%) but also highly congruous, whereas there is a larger deviation in the prediction with comprehensive axial wear coefficient(accuracy 41%, which is in agreement with the prediction of disc cutters' life in the field). This paper puts forth a new method concerning prediction of life span and wear of TBM disc cutters as well as timing for replacing disc cutters.

  17. Experimental study using diode laser in discs: the healing process in discs and adjacent vertebrae after laser irradiation

    NASA Astrophysics Data System (ADS)

    Naga, Kumi; Nakai, Sadaaki; Maehara, Kazuyuki; Nishimoto, Seiji

    2004-09-01

    The direct and secondary changes following diode laser irradiation of intervertebral discs were studied in rabbits. A quartz fiber was inserted into the discs, and laser irradiation was applied. Subsequently, the lumbar vertebrae were extracted en bloc, and subjected to sagittal magnetic resonance (MR) imaging and histologic examination immediately after irradiation, and 3, 12, and 24 weeks after irradiation. MR images showed low signal intensity of the intervertebral discs on T2-weighted images 3 weeks after irradiation, which remained unchanged to 24 weeks. Although the signal intensity of the adjacent vertebral bodies remained unchanged on T1-weighted images, the intensity was high on T2-weighted images 3 weeks after irradiation, but had reverted to normal or was low 12 to 24 weeks after irradiation. On histologic examination, the inner layer of the annulus fibrosus was seen to protrude into the void created by vaporization of the nucleus pulposus 3 weeks after irradiation. Multinuclear chondrocytes were observed, as if the disc was being reconstructed. Fibrous tissue in the epiphysis and metaphysis was observed soon after irradiation but decreased over time and was replaced by normal bone marrow.

  18. Black hole accretion disc impacts

    NASA Astrophysics Data System (ADS)

    Pihajoki, P.

    2016-04-01

    We present an analytic model for computing the luminosity and spectral evolution of flares caused by a supermassive black hole impacting the accretion disc of another supermassive black hole. Our model includes photon diffusion, emission from optically thin regions and relativistic corrections to the observed spectrum and time-scales. We test the observability of the impact scenario with a simulated population of quasars hosting supermassive black hole binaries. The results indicate that for a moderate binary mass ratio of 0.3, and impact distances of 100 primary Schwarzschild radii, the accretion disc impacts can be expected to equal or exceed the host quasar in brightness at observed wavelength λ = 510 nm up to z = 0.6. We conclude that accretion disc impacts may function as an independent probe for supermassive black hole binaries. We release the code used for computing the model light curves to the community.

  19. Laser engineering of spine discs

    NASA Astrophysics Data System (ADS)

    Sobol, E.; Zakharkina, O.; Baskov, A.; Shekhter, A.; Borschenko, I.; Guller, A.; Baskov, V.; Omelchenko, A.; Sviridov, A.

    2009-04-01

    The laser engineering of intervertebral discs is one of the branch of medical physics aimed at the development of minimally invasive laser medical techniques based on the effect of the controlled (time- and space-modulated) laser radiation on the structure and the field of mechanical stress of biological tissues. A new method for the laser engineering of the intervertebral discs and the differences of this approach from the existing physical methods of medical treatment are considered. The newly formed tissues of animals and humans are hystologically studied. Possible regeneration processes are discussed. A control system that provides for the treatment efficiency and safety is developed. The new laser medical equipment that is designed for the laser engineering of intervertebral discs is described, and the corresponding results of the clinical application are presented.

  20. Debris disc formation induced by planetary growth

    NASA Astrophysics Data System (ADS)

    Kobayashi, H.; Löhne, T.

    2014-08-01

    Several hundred stars older than 10 million years have been observed to have infrared excesses. These observations are explained by dust grains formed by the collisional fragmentation of hidden planetesimals. Such dusty planetesimal discs are known as debris discs. In a dynamically cold planetesimal disc, collisional coagulation of planetesimals produces planetary embryos which then stir the surrounding leftover planetesimals. Thus, the collisional fragmentation of planetesimals that results from planet formation forms a debris disc. We aim to determine the properties of the underlying planetesimals in debris discs by numerically modelling the coagulation and fragmentation of planetesimal populations. The brightness and temporal evolution of debris discs depend on the radial distribution of planetesimal discs, the location of their inner and outer edges, their total mass, and the size of planetesimals in the disc. We find that a radially narrow planetesimal disc is most likely to result in a debris disc that can explain the trend of observed infrared excesses of debris discsvvv around G-type stars, for which planet formation occurs only before 100 million years. Early debris disc formation is induced by planet formation, while the later evolution is explained by the collisional decay of leftover planetesimals around planets that have already formed. Planetesimal discs with underlying planetesimals of radii ˜100 km at ≈30 au most readily explain the Spitzer Space Telescope 24 and 70 μm fluxes from debris discs around G-type stars.

  1. Measurement of position deviation and eccentricity for μ-disc-type inductive micro-motor

    NASA Astrophysics Data System (ADS)

    Lin, Chih-Che; Tsai, Nan-Chyuan

    2015-12-01

    An innovative capacitive gap-sensing readout circuit to replace traditional gap sensor is designed to measure the motion of the levitated micro-disc embedded in an inductive micro-motor. Twelve equivalent capacitor pairs are constructed to detect the position deviation of the disc. As the position deviation of disc occurs, the capacitances of the corresponding capacitor pairs are altered. In addition, by applying the effects of inertial force and centrifugal force, an innovative non-contact measurement method to quantify the unbalance degree of the micro-disc, i.e., eccentricity, is also proposed. By commercial computer simulations and realistic experiments undertaken, the performance of the proposed capacitive gap-sensing readout circuit has been successfully verified. The mean of output voltage of gap-sensing readout circuit is about 327 mV under the position deviation of the disc being 8 μm. Moreover, the unbalance degree of the disc is approximately proportional to the square of the position deviation of the disc.

  2. The truncated and evolving inner accretion disc of the black hole GX 339-4

    NASA Astrophysics Data System (ADS)

    Plant, D. S.; Fender, R. P.; Ponti, G.; Muñoz-Darias, T.; Coriat, M.

    2015-01-01

    The nature of accretion onto stellar mass black holes in the low/hard state remains unresolved, with some evidence suggesting that the inner accretion disc is truncated and replaced by a hot flow. However, the detection of relativistic broadened Fe emission lines, even at relatively low luminosities, seems to require an accretion disc extending fully to its innermost stable circular orbit. Modelling such features is, however, highly susceptible to degeneracies, which could easily bias any interpretation. We present the first systematic study of the Fe line region to track how the inner accretion disc evolves in the low/hard state of the black hole GX 339-4. Our four observations display increased broadening of the Fe line over two magnitudes in luminosity, which we use to track any variation of the disc inner radius. We find that the disc extends closer to the black hole at higher luminosities, but is consistent with being truncated throughout the entire low/hard state, a result which renders black hole spin estimates inaccurate at these stages of the outburst. Furthermore, we show that the evolution of our spectral inner disc radius estimates corresponds very closely to the trend of the break frequency in Fourier power spectra, supporting the interpretation of a truncated and evolving disc in the hard state.

  3. Determination of the intervertebral disc space from CT images of the lumbar spine

    NASA Astrophysics Data System (ADS)

    Korez, Robert; Å tern, Darko; Likar, Boštjan; Pernuš, Franjo; Vrtovec, Tomaž

    2014-03-01

    Degenerative changes of the intervertebral disc are among the most common causes of low back pain, where for individuals with significant symptoms surgery may be needed. One of the interventions is the total disc replacement surgery, where the degenerated disc is replaced by an artificial implant. For designing implants with good bone contact and continuous force distribution, the morphology of the intervertebral disc space and vertebral body endplates is of considerable importance. In this study we propose a method for the determination of the intervertebral disc space from three-dimensional (3D) computed tomography (CT) images of the lumbar spine. The first step of the proposed method is the construction of a model of vertebral bodies in the lumbar spine. For this purpose, a chain of five elliptical cylinders is initialized in the 3D image and then deformed to resemble vertebral bodies by introducing 25 shape parameters. The parameters are obtained by aligning the chain to the vertebral bodies in the CT image according to image intensity and appearance information. The determination of the intervertebral disc space is finally achieved by finding the planes that fit the endplates of the obtained parametric 3D models, and placing points in the space between the planes of adjacent vertebrae that enable surface reconstruction of the intervertebral disc space. The morphometric analysis of images from 20 subjects yielded 11:3 +/- 2:6, 12:1 +/- 2:4, 12:8 +/- 2:0 and 12:9 +/- 2:7 cm3 in terms of L1-L2, L2-L3, L3-L4 and L4-L5 intervertebral disc space volume, respectively.

  4. Elbow replacement - discharge

    MedlinePlus

    Total elbow arthroplasty - discharge; Endoprosthetic elbow replacement - discharge ... You had surgery to replace your elbow joint with artificial joint parts (prosthetics). The surgeon made a cut (incision) in the back of your upper or lower arm and ...

  5. Partial knee replacement - slideshow

    MedlinePlus

    ... page: //medlineplus.gov/ency/presentations/100225.htm Partial knee replacement - series To use the sharing features on ... A.M. Editorial team. Related MedlinePlus Health Topics Knee Replacement A.D.A.M., Inc. is accredited ...

  6. Nicotine replacement therapy

    MedlinePlus

    ... If wearing the patch at night causes odd dreams, try sleeping without the patch. People who smoke ... cessation - nicotine replacement; Tobacco - nicotine replacement therapy References American Cancer Society. Guide to quitting smoking. Last revised ...

  7. Partial knee replacement

    MedlinePlus

    Most people recover quickly and have much less pain than they did before surgery. People who have a partial knee replacement recover faster than those who have a total knee replacement. Many people are able to walk ...

  8. Optical Discs: New Storage Media for Education.

    ERIC Educational Resources Information Center

    Helgerson, Linda W.

    1987-01-01

    Discusses three new advances in the use of optical disc technology in education. Describes the storage formats and capabilities of the videodisc, the compact disc, and the optical write-once disc. Contrasts the three technologies in terms of their production requirements, the hardware involved, and some projected applications in education. (TW)

  9. Electromagnetic Levitation of a Disc

    ERIC Educational Resources Information Center

    Valle, R.; Neves, F.; de Andrade, R., Jr.; Stephan, R. M.

    2012-01-01

    This paper presents a teaching experiment that explores the levitation of a disc of ferromagnetic material in the presence of the magnetic field produced by a single electromagnet. In comparison to the classical experiment of the levitation of a sphere, the main advantage of the proposed laboratory bench is that the uniform magnetic field…

  10. Optical Disc Applications in Libraries.

    ERIC Educational Resources Information Center

    Andre, Pamela Q. J.

    1989-01-01

    Discusses a variety of library applications of optical disc storage technology, including CD-ROM, digital videodisc, and WORM. Research and development projects at the Library of Congress, National Library of Medicine, and National Agricultural Library are described, products offered by library networks are reviewed, and activities in academic and…

  11. The short stem: promises and pitfalls.

    PubMed

    Stulberg, S D; Patel, R M

    2013-11-01

    Conventional uncemented femoral implants provide dependable long-term fixation in patients with a wide range of functional requirements. Yet challenges associated with proximal-distal femoral dimensional mismatch, preservation of bone stock, and minimally invasive approaches have led to exploration into alternative implant designs. Short stem designs focusing on a stable metaphyseal fit have emerged to address these issues in total hip replacement (THR). Uncemented metaphyseal-engaging short stem implants are stable and are associated with proximal bone remodeling closer to the metaphysis when compared with conventional stems and they also have comparable clinical performances. Short stem metaphyseal-engaging implants can meet the goals of a successful THR, including tolerating a high level of patient function, as well as durable fixation. PMID:24187354

  12. Anticoagulant conversion in the elderly: pitfalls.

    PubMed

    Al-Nasser, Bassam

    2016-05-01

    The prevalence of medical conditions representing a risk for thromboembolic complications and requiring antithrombotic therapy increases gradually with age. Two cases of fatal noncritical organ bleeding complication that occurred during the conversion period from initial fondaparinux to vitamin K antagonist are presented. An 81-year-old obese female patient (body mass index 43 kg/m(2)) with previous postoperative thrombosis underwent uneventful total knee replacement under spinal anesthesia. She presented with popliteal hematoma during conversion to oral anticoagulant. A 92-year-old female patient (body mass index 33 kg/m(2)) with left lower limb thrombosis was referred to our orthopedics department from her senior citizens' home for right lower limb hematoma and ischemia that occurred during conversion to oral anticoagulant. Thromboembolic and bleeding events in the elderly are real public health problems. Specific guidelines dedicated to this particular population are needed, which will improve the management of anticoagulation and decrease risk of complications. PMID:26547115

  13. A Structurally and Functionally Biomimetic Biphasic Scaffold for Intervertebral Disc Tissue Engineering

    PubMed Central

    Choy, Andrew Tsz Hang; Chan, Barbara Pui

    2015-01-01

    Tissue engineering offers high hopes for the treatment of intervertebral disc (IVD) degeneration. Whereas scaffolds of the disc nucleus and annulus have been extensively studied, a truly biomimetic and mechanically functional biphasic scaffold using naturally occurring extracellular matrix is yet to be developed. Here, a biphasic scaffold was fabricated with collagen and glycosaminoglycans (GAGs), two of the most abundant extracellular matrix components in the IVD. Following fabrication, the scaffold was characterized and benchmarked against native disc. The biphasic scaffold was composed of a collagen-GAG co-precipitate making up the nucleus pulposus-like core, and this was encapsulated in multiple lamellae of photochemically crosslinked collagen membranes comprising the annulus fibrosus-like lamellae. On mechanical testing, the height of our engineered disc recovered by ~82-89% in an annulus-independent manner, when compared with the 99% recovery exhibited by native disc. The annulus-independent nature of disc height recovery suggests that the fluid replacement function of the engineered nucleus pulposus core might mimic this hitherto unique feature of native disc. Biphasic scaffolds comprised of 10 annulus fibrosus-like lamellae had the best overall mechanical performance among the various designs owing to their similarity to native disc in most aspects, including elastic compliance during creep and recovery, and viscous compliance during recovery. However, the dynamic mechanical performance (including dynamic stiffness and damping factor) of all the biphasic scaffolds was similar to that of the native discs. This study contributes to the rationalized design and development of a biomimetic and mechanically viable biphasic scaffold for IVD tissue engineering. PMID:26115332

  14. Peripheral disc margin shape and internal disc derangement: imaging correlation in significantly painful discs identified at provocation lumbar discography.

    PubMed

    Bartynski, W S; Rothfus, W E

    2012-06-01

    Annular margin shape is used to characterize lumbar disc abnormality on CT/MR imaging studies. Abnormal discs also have internal derangement including annular degeneration and radial defects. The purpose of this study was to evaluate potential correlation between disc-margin shape and annular internal derangement on post-discogram CT in significantly painful discs encountered at provocation lumbar discography (PLD). Significantly painful discs were encountered at 126 levels in 86 patients (47 male, 39 female) studied by PLD where no prior surgery had been performed and response to intradiscal lidocaine after provocation resulted in either substantial/total relief or no improvement after lidocaine administration. Post-discogram CT and discogram imaging was evaluated for disc-margin characteristics (bulge/protrusion), features of disc internal derangement (radial annular defect [RD: radial tear/fissure/annular gap], annular degeneration) and presence/absence of discographic contrast leakage. In discs with focal protrusion, 50 of 63 (79%) demonstrated Grade 3 RD with 13 (21%) demonstrating severe degenerative change only. In discs with generalized-bulge-only, 48 of 63 (76%) demonstrated degenerative change only (primarily Dallas Grade 3) with 15 of 63 (24%) demonstrating a RD (Dallas Grade 3). Differences were highly statistically significant (p<0.001). Pain elimination with intra-discal lidocaine correlated with discographic contrast leakage (p<0.001). Disc-margin shape correlates with features of internal derangement in significantly painful discs encountered at PLD. Discs with focal protrusion typically demonstrate RD while generalized bulging discs typically demonstrated degenerative changes only (p<0.001). Disc-margin shape may provide an important imaging clue to the cause of chronic discogenic low back pain. PMID:22681741

  15. Peripheral Disc Margin Shape and Internal Disc Derangement: Imaging Correlation in Significantly Painful Discs Identified at Provocation Lumbar Discography

    PubMed Central

    Bartynski, W.S.; Rothfus, W.E.

    2012-01-01

    Summary Annular margin shape is used to characterize lumbar disc abnormality on CT/MR imaging studies. Abnormal discs also have internal derangement including annular degeneration and radial defects. The purpose of this study was to evaluate potential correlation between disc-margin shape and annular internal derangement on post-discogram CT in significantly painful discs encountered at provocation lumbar discography (PLD). Significantly painful discs were encountered at 126 levels in 86 patients (47 male, 39 female) studied by PLD where no prior surgery had been performed and response to intradiscal lidocaine after provocation resulted in either substantial/total relief or no improvement after lidocaine administration. Post-discogram CT and discogram imaging was evaluated for disc-margin characteristics (bulge/protrusion), features of disc internal derangement (radial annular defect [RD: radial tear/fissure/annular gap], annular degeneration) and presence/absence of discographic contrast leakage. In discs with focal protrusion, 50 of 63 (79%) demonstrated Grade 3 RD with 13 (21%) demonstrating severe degenerative change only. In discs with generalized-bulge-only, 48 of 63 (76%) demonstrated degenerative change only (primarily Dallas Grade 3) with 15 of 63 (24%) demonstrating a RD (Dallas Grade 3). Differences were highly statistically significant (p<0.001). Pain elimination with intra-discal lidocaine correlated with discographic contrast leakage (p<0.001). Disc-margin shape correlates with features of internal derangement in significantly painful discs encountered at PLD. Discs with focal protrusion typically demonstrate RD while generalized bulging discs typically demonstrated degenerative changes only (p<0.001). Disc-margin shape may provide an important imaging clue to the cause of chronic discogenic low back pain. PMID:22681741

  16. Three-piece Inflatable Penile Prosthesis: Surgical Techniques and Pitfalls

    PubMed Central

    Al-Enezi, Ahmad; Al-Khadhari, Sulaiman; Al-Shaiji, Tariq F.

    2011-01-01

    Penile prosthesis surgery plays a vital role in the treatment of erectile dysfunction (ED). As far as outcome is concerned, it is one of the most rewarding procedures for both patients and surgeons. We describe our surgical technique for implantation of the three-piece inflatable penile prosthesis and point out the major surgical pitfalls accompanying this procedure and their specific management. The psychological outcome of penile prosthesis surgery is also discussed. Different surgical approaches are available when performing the procedure. A number of procedure-related problems can be encountered and a thorough knowledge of these is of paramount importance. Penile prosthesis surgery has a favorable psychological outcome. Surgery for implantation of an inflatable penile prosthesis is a rewarding procedure, with a high yield of patient satisfaction. Urologists should have thorough understanding of the surgical pitfalls peculiar to this procedure and their management. PMID:22413049

  17. Herpetological Monitoring Using a Pitfall Trapping Design in Southern California

    USGS Publications Warehouse

    Fisher, Robert; Stokes, Drew; Rochester, Carlton; Brehme, Cheryl; Hathaway, Stacie; Case, Ted

    2008-01-01

    The steps necessary to conduct a pitfall trapping survey for small terrestrial vertebrates are presented. Descriptions of the materials needed and the methods to build trapping equipment from raw materials are discussed. Recommended data collection techniques are given along with suggested data fields. Animal specimen processing procedures, including toe- and scale-clipping, are described for lizards, snakes, frogs, and salamanders. Methods are presented for conducting vegetation surveys that can be used to classify the environment associated with each pitfall trap array. Techniques for data storage and presentation are given based on commonly use computer applications. As with any study, much consideration should be given to the study design and methods before beginning any data collection effort.

  18. Sealing arrangement with annular flexible disc

    DOEpatents

    Pennell, William E.; Honigsberg, Charles A.

    1983-01-01

    Fluid sealing arrangements including an annular shaped flexible disc having enlarged edges disposed within channel-shaped annular receptacles which are spaced from one another. The receptacles form an annular region for contacting and containing the enlarged edges of the disc, and the disc is preloaded to a conical configuration. The disc is flexibly and movably supported within the receptacles so that unevenly distributed relative motion between the components containing the receptacles is accommodated without loss of sealing contact between the edges of the disc and the walls of the receptacles.

  19. In vitro biomechanics of cervical disc arthroplasty with the ProDisc-C total disc implant.

    PubMed

    DiAngelo, Denis J; Foley, Kevin T; Morrow, Brian R; Schwab, John S; Song, Jung; German, John W; Blair, Eve

    2004-09-15

    An in vitro biomechanical study was conducted to compare the effects of disc arthroplasty and anterior cervical fusion on cervical spine biomechanics in a multilevel human cadaveric model. Three spine conditions were studied: harvested, single-level cervical disc arthroplasty, and single-level fusion. A programmable testing apparatus was used that replicated physiological flexion/extension, lateral bending, and axial rotation. Measurements included vertebral motion, applied load, and bending moments. Relative rotations at the superior, treated, and inferior motion segment units (MSUs) were normalized with respect to the overall rotation of those three MSUs and compared using a one-way analysis of variance with Student-Newman-Keuls test (p < 0.05). Simulated fusion decreased motion across the treated site relative to the harvested and disc arthroplasty conditions. The reduced motion at the treated site was compensated at the adjacent segments by an increase in motion. For all modes of testing, use of an artificial disc prosthesis did not alter the motion patterns at either the instrumented level or adjacent segments compared with the harvested condition, except in extension. PMID:15636563

  20. Modeling emission from the first explosions: pitfalls and problems

    SciTech Connect

    Fryer, Christopher Lee; Whalen, Daniel J; Frey, Lucille H

    2010-01-01

    Observations of the explosions of the population III stars have the potential to teach us much about the formation and evolution of these zero metallicity objects. But to reach this potential, we must tie the observed emission to and explosion model. This requires accurate light-curve/spectral calculations. Here we discuss many of the pitfalls and problems involved in such calculations, presenting some preliminary results from radiation-hydrodynamics calculations.

  1. Using demographic data to better interpret pitfall trap catches

    PubMed Central

    Matalin, Andrey V.; Makarov, Kirill V.

    2011-01-01

    Abstract The results of pitfall trapping are often interpreted as abundance in a particular habitat. At the same time, there are numerous cases of almost unrealistically high catches of ground beetles in seemingly unsuitable sites. The correlation of catches by pitfall trapping with the true distribution and abundance of Carabidae needs corroboration. During a full year survey in 2006/07 in the Lake Elton region (Volgograd Area, Russia), 175 species of ground beetles were trapped. Considering the differences in demographic structure of the local populations, and not their abundances, three groups of species were recognized: residents, migrants and sporadic. In residents, the demographic structure of local populations is complete, and their habitats can be considered “residential”. In migrants and sporadic species, the demographic structure of the local populations is incomplete, and their habitats can be considered “transit”. Residents interact both with their prey and with each other in a particular habitat. Sporadic species are hardly important to a carabid community because of their low abundances. The contribution of migrants to the structure of carabid communities is not apparent and requires additional research. Migrants and sporadic species represent a “labile” component in ground beetles communities, as opposed to a “stable” component, represented by residents. The variability of the labile component substantially limits our interpretation of species diversity in carabid communities. Thus, the criteria for determining the most abundant, or dominant species inevitably vary because the abundance of migrants in some cases can be one order of magnitude higher than that of residents. The results of pitfall trapping adequately reflect the state of carabid communities only in zonal habitats, while azonal and disturbed habitats are merely transit ones for many species of ground beetles. A study of the demographic structure of local populations and

  2. Pitfall in MR imaging of lymphadenopathy after lymphangiography.

    PubMed

    Buckwalter, K A; Ellis, J H; Baker, D E; Borello, J A; Glazer, G M

    1986-12-01

    In two patients examined with magnetic resonance (MR) imaging after lymphangiography, opacified pelvic lymph nodes could not be distinguished from subcutaneous or retroperitoneal fat because of the short T1 and long T2 relaxation times of lymphangiographic contrast media. Opacified nodes removed from one patient had relaxation times similar to those of fat. Thus, assessment of lymphadenopathy with MR imaging should be performed before lymphangiography to obviate this potential pitfall. PMID:3024208

  3. [Suture foreign body reaction as a mammographic pitfall].

    PubMed

    Plagborg, G J; Andersen, H K

    2000-02-14

    A mammographic pitfall is presented. After lumpectomy owing to cancer in the breast a woman developed an immediate allergic reaction presumably caused by the subcutaneous sutures (vicryl). After adjuvant irradiation the breast became swollen and mammography gave suspicion of a recurrent breast cancer. Surgical excision was performed and examination of the biopsy specimen showed a foreign body reaction to the suture material with fibrosis and eosinophilia. PMID:10740437

  4. From the Solar Neighbourhood to the Galactic Disc(s)

    NASA Astrophysics Data System (ADS)

    Casagrande, L.

    2012-08-01

    We present a re-analysis of the Geneva-Copenhagen Survey (GCS), based on improved effective temperature and metallicity scales, which also provide a better match to theoretical isochrones. The latter are used for a Bayesian investigation on stellar ages. With respect to previous analyses, our stars are on average 100 K hotter and 0.1 dex more metal rich, which shifts the peak of the metallicity distribution function (MDF) around the solar value. From Strömgren photometry we are able to derive for the first time a proxy for alpha elements, which enables us to perform a tentative dissection of the chemical thin and thick disc. We find evidence for the latter being composed of an old, mildly but systematically alpha-enhanced population that extends to super solar metallicities. These findings help to constrain different processes potentially relevant in the build-up of the Milky Way disc.

  5. Intradural herniation of lumbar intervertebral discs.

    PubMed

    Hodge, C J; Binet, E F; Kieffer, S A

    1978-12-01

    A case of intradural rupture of a lumbar intervertebral disc is reported, and the literature is reviewed. The majority of intradural disc herniations occur at the L4--5 level. These patients usually have neurologic deficits more severe than those found in the much more common extradural disc herniations. The myelographic picture varies from an irregularly marginated intradural lesion overlying the disc space to a complete block. The common factor allowing intradural disc herniation is probably dense adhesions between the dura and the posterior longitudinal ligament, preventing the more common lateral extradural disc herniation. Intradural disc herniation should be included in the differential diagnosis of lumbar intradural lesions causing nerve root or cauda equina compression. PMID:741242

  6. Pitfalls in diagnosing mitochondrial neurogastrointestinal encephalomyopathy.

    PubMed

    Filosto, Massimiliano; Scarpelli, Mauro; Tonin, Paola; Testi, Silvia; Cotelli, Maria Sofia; Rossi, Mara; Salvi, Andrea; Grottolo, Alberto; Vielmi, Valentina; Todeschini, Alice; Fabrizi, Gian Maria; Padovani, Alessandro; Tomelleri, Giuliano

    2011-12-01

    Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is an autosomal recessive disorder caused by mutations in the gene encoding thymidine phosphorylase and is characterized by external ophthalmoparesis, gastrointestinal dysmotility, leukoencephalopathy, and neuropathy. The availability of new therapeutic options (peritoneal dialysis, allogeneic stem cell transplantation, enzyme replacement) makes it necessary to diagnose the disease early, which is not always achieved due to the difficulty in recognizing this disorder, especially in case of atypical presentation. We describe three MNGIE patients with atypical onset of the disease. In the first patient the main symptoms were long-standing chronic fever, recurrent acute migrant arthritis, and gastrointestinal disorders mimicking autoimmune or inflammatory intestinal diseases; the second patient complained only of exercise intolerance and muscle cramps, and the third patient had a CIDP-like polyneuropathy. This study stresses the insidious heterogeneous clinical onset of some cases of MNGIE, expands the spectrum of the phenotype, and suggests considering MNGIE in the differential diagnosis of enteropathic arthritis, isolated exercise intolerance, and inflammatory polyneuropathies not responsive to the usual treatment. A better understanding of the clinical heterogeneity of MNGIE is necessary in order to diagnose atypical cases and promote early diagnosis, which is now absolutely necessary in view of the new available therapies. PMID:21503690

  7. A Washington Perspective on Women and Networking: The Power and the Pitfalls.

    ERIC Educational Resources Information Center

    Green, Madeleine F.

    1982-01-01

    Describes two successful, institutionalized networking programs of the American Council on Education. Discusses the potential benefits and pitfalls of networking especially as they apply to women. (RC)

  8. [Innervation of the intervertebral disc].

    PubMed

    García-Cosamalón, José; Fernández-Fernández, Javier; González-Martínez, Emilio; Ibáñez-Plágaro, Javier; Robla Costales, Javier; Martínez-Madrigal, Milton; López Muñíz, Alfonso; del Valle, Miguel Enrique; Vega, José Antonio

    2013-01-01

    Until very recently, intervertebral disc innervation was a subject of considerable debate. Nowadays, the introduction of inmunohistochemical techniques associated to specific antibodies and studies with retrograde tracers in nerves have allowed greater understanding of disc innervation in physiological and pathological conditions and also endings characteristics and their patterns of distribution in both situations. The existing controversies regarding structural basis of discogenic pain, have raised the interest of knowing the influence of innervation in back pain from discal origin and its characteristics. Today, we know that pathologic neoinnervation accompanying radial fissures is an important factor in the genesis of discogenic pain; within a complex mechanism in which other neurobiomechemical, inflammatory and biomechanical factors are involved. PMID:23582224

  9. Ion replacement electrorefining

    SciTech Connect

    Willit, J.L.; Tomczuk, Z.; Miller, W.E.; Laidler, J.J.

    1994-04-01

    We are developing a two-step electrochemical process for purifying and separating metals called ion replacement electrorefining. In each step, metal cations formed by oxidation at an electrode replace other metal cations that are reduced at another elecmae. Using this approach, we have separated or purified uranium, dysprosium, and lanthanum on a laboratory scale. This paper explains the ion replacement concept and presents results of these demonstration experiments.

  10. Artificial Discs for Lumbar and Cervical Degenerative Disc Disease –Update

    PubMed Central

    2006-01-01

    Executive Summary Objective To assess the safety and efficacy of artificial disc replacement (ADR) technology for degenerative disc disease (DDD). Clinical Need Degenerative disc disease is the term used to describe the deterioration of 1 or more intervertebral discs of the spine. The prevalence of DDD is roughly described in proportion to age such that 40% of people aged 40 years have DDD, increasing to 80% among those aged 80 years or older. Low back pain is a common symptom of lumbar DDD; neck and arm pain are common symptoms of cervical DDD. Nonsurgical treatments can be used to relieve pain and minimize disability associated with DDD. However, it is estimated that about 10% to 20% of people with lumbar DDD and up to 30% with cervical DDD will be unresponsive to nonsurgical treatments. In these cases, surgical treatment is considered. Spinal fusion (arthrodesis) is the process of fusing or joining 2 bones and is considered the surgical gold standard for DDD. Artificial disc replacement is the replacement of the degenerated intervertebral disc with an artificial disc in people with DDD of the lumbar or cervical spine that has been unresponsive to nonsurgical treatments for at least 6 months. Unlike spinal fusion, ADR preserves movement of the spine, which is thought to reduce or prevent the development of adjacent segment degeneration. Additionally, a bone graft is not required for ADR, and this alleviates complications, including bone graft donor site pain and pseudoarthrosis. It is estimated that about 5% of patients who require surgery for DDD will be candidates for ADR. Review Strategy The Medical Advisory Secretariat conducted a computerized search of the literature published between 2003 and September 2005 to answer the following questions: What is the effectiveness of ADR in people with DDD of the lumbar or cervical regions of the spine compared with spinal fusion surgery? Does an artificial disc reduce the incidence of adjacent segment degeneration (ASD

  11. Hydrodynamic instability in eccentric astrophysical discs

    NASA Astrophysics Data System (ADS)

    Barker, A. J.; Ogilvie, G. I.

    2014-12-01

    Eccentric Keplerian discs are believed to be unstable to three-dimensional hydrodynamical instabilities driven by the time-dependence of fluid properties around an orbit. These instabilities could lead to small-scale turbulence, and ultimately modify the global disc properties. We use a local model of an eccentric disc, derived in a companion paper, to compute the non-linear vertical (`breathing mode') oscillations of the disc. We then analyse their linear stability to locally axisymmetric disturbances for any disc eccentricity and eccentricity gradient using a numerical Floquet method. In the limit of small departures from a circular reference orbit, the instability of an isothermal disc is explained analytically. We also study analytically the small-scale instability of an eccentric neutrally stratified polytropic disc with any polytropic index using a Wentzel-Kramers-Brillouin (WKB) approximation. We find that eccentric discs are generically unstable to the parametric excitation of small-scale inertial waves. The non-linear evolution of these instabilities should be studied in numerical simulations, where we expect them to lead to a decay of the disc eccentricity and eccentricity gradient as well as to induce additional transport and mixing. Our results highlight that it is essential to consider the three-dimensional structure of eccentric discs, and their resulting vertical oscillatory flows, in order to correctly capture their evolution.

  12. Proto-planetary disc evolution and dispersal

    NASA Astrophysics Data System (ADS)

    Rosotti, Giovanni Pietro

    2015-05-01

    Planets form from gas and dust discs in orbit around young stars. The timescale for planet formation is constrained by the lifetime of these discs. The properties of the formed planetary systems depend thus on the evolution and final dispersal of the discs, which is the main topic of this thesis. Observations reveal the existence of a class of discs called "transitional", which lack dust in their inner regions. They are thought to be the last stage before the complete disc dispersal, and hence they may provide the key to understanding the mechanisms behind disc evolution. X-ray photoevaporation and planet formation have been studied as possible physical mechanisms responsible for the final dispersal of discs. However up to now, these two phenomena have been studied separately, neglecting any possible feedback or interaction. In this thesis we have investigated what is the interplay between these two processes. We show that the presence of a giant planet in a photo-evaporating disc can significantly shorten its lifetime, by cutting the inner regions from the mass reservoir in the exterior of the disc. This mechanism produces transition discs that for a given mass accretion rate have larger holes than in models considering only X-ray photo-evaporation, constituting a possible route to the formation of accreting transition discs with large holes. These discs are found in observations and still constitute a puzzle for the theory. Inclusion of the phenomenon called "thermal sweeping", a violent instability that can destroy a whole disc in as little as 10 4 years, shows that the outer disc left can be very short-lived (depending on the X-ray luminosity of the star), possibly explaining why very few non accreting transition discs are observed. However the mechanism does not seem to be efficient enough to reconcile with observations. In this thesis we also show that X-ray photo-evaporation naturally explains the observed correlation between stellar masses and accretion

  13. Disc erosion in Models 103 and 104 of Beall mitral valve prostheses

    PubMed Central

    Gómez, Ricardo; Verduras, María José; Lopez-Quintana, Alfonso; Riera, Luis; Zerolo, Ignacio; Martinez-Bordiu, Cristóbal

    1981-01-01

    Three cases of severe disc variance and erosion of the Teflon-disc Beall mitral valve prosthesis (Models 103 and 104) are reported. In two patients, the Beall mitral valves were excised and replaced with two Björk-Shiley mitral valves. The remaining patient did not survive, and at autopsy, the lens was found at the aortic bifurcation level. Because of this potentially lethal complication, careful follow-up of patients with Beall mitral valve prostheses (Models 103 and 104) is recommended. Images PMID:15216211

  14. Factors regulating viable cell density in the intervertebral disc: blood supply in relation to disc height

    PubMed Central

    Boubriak, Olga A; Watson, Natasha; Sivan, Sarit S; Stubbens, Naomi; Urban, Jill P G

    2013-01-01

    The intervertebral disc is an avascular tissue, maintained by a small population of cells that obtain nutrients mainly by diffusion from capillaries at the disc–vertebral body interface. Loss of this nutrient supply is thought to lead to disc degeneration, but how nutrient supply influences viable cell density is unclear. We investigated two factors that influence nutrient delivery to disc cells and hence cell viability: disc height and blood supply. We used bovine caudal discs as our model as these show a gradation in disc height. We found that although disc height varied twofold from the largest to the smallest disc studied, it had no significant effect on cell density, unlike the situation found in articular cartilage. The density of blood vessels supplying the discs was markedly greater for the largest disc than the smallest disc, as was the density of pores allowing capillary penetration through the bony endplate. Results indicate that changes in blood vessels in the vertebral bodies supplying the disc, as well as changes in endplate architecture appear to influence density of cells in intervertebral discs. PMID:23311982

  15. Radiation Source Replacement Workshop

    SciTech Connect

    Griffin, Jeffrey W.; Moran, Traci L.; Bond, Leonard J.

    2010-12-01

    This report summarizes a Radiation Source Replacement Workshop in Houston Texas on October 27-28, 2010, which provided a forum for industry and researchers to exchange information and to discuss the issues relating to replacement of AmBe, and potentially other isotope sources used in well logging.

  16. Intervertebral disc extrusion in six cats.

    PubMed

    Knipe, M F; Vernau, K M; Hornof, W J; LeCouteur, R A

    2001-09-01

    Existing reports concerning intervertebral disc disease (IVDD) have focused almost exclusively on dogs, although a small number of individual case reports of IVDD of cats has been published. The medical records of six cats with IVDD were reviewed. Radiographic studies confirmed narrowed intervertebral disc spaces, mineralised intervertebral discs, and one or more extradural compressive lesions of the spinal cord in each cat. All disc extrusions were located in the thoracolumbar region. Surgical decompression of the spinal cord was achieved in all cats by means of hemilaminectomy and removal of compressive extradural material confirmed to be degenerative disc material. Good to excellent neurological recovery was noted in five of the six cats included in this report. Based on this review, it appears that IVDD of cats has many similarities to IVDD of dogs, and that healthy cats with acute intervertebral disc extrusion(s) respond favourably to surgical decompression of the spinal cord. PMID:11876633

  17. Disc repositioning: does it really work?

    PubMed

    Gonçalves, João Roberto; Cassano, Daniel Serra; Rezende, Luciano; Wolford, Larry M

    2015-02-01

    Although limited, there is evidence to support the assumption that temporomandibular joint (TMJ) articular disc repositioning indeed works; to date, there is no evidence that TMJ articular disc repositioning does not work. Despite the controversy among professionals in private practice and academia, TMJ articular disc repositioning is a procedure based on (still limited) evidence; the opposition is based solely on clinical preference and influenced by the ability to perform it or not. PMID:25483446

  18. Accretion Discs Show Their True Colours

    NASA Astrophysics Data System (ADS)

    2008-07-01

    Quasars are the brilliant cores of remote galaxies, at the hearts of which lie supermassive black holes that can generate enough power to outshine the Sun a trillion times. These mighty power sources are fuelled by interstellar gas, thought to be sucked into the hole from a surrounding 'accretion disc'. A paper in this week's issue of the journal Nature, partly based on observations collected with ESO's Very Large Telescope, verifies a long-standing prediction about the intensely luminous radiation emitted by these accretion discs. Uncovering the disc ESO PR Photo 21/08 Uncovering the inner disc "Astronomers were puzzled by the fact that the best models of these discs couldn't quite be reconciled with some of the observations, in particular, with the fact that these discs did not appear as blue as they should be," explains lead-author Makoto Kishimoto. Such a discrepancy could be the signal that there was something very wrong with the models. With his colleagues, he investigated this discrepancy by studying the polarised light from six quasars. This enabled them to demonstrate that the disc spectrum is as blue as predicted. "The crucial observational difficulty here has been that the disc is surrounded by a much larger torus containing hot dust, whose light partly outshines that of the disc," says Kishimoto. "Because the light coming from the disc is scattered in the disc vicinity and thus polarised, by observing only polarised light from the quasars, one can uncover the buried light from the disc." In a similar way that a fisherman would wear polarised sunglasses to help get rid of the glare from the water surface and allow him to see more clearly under the water, the filter on the telescope allowed the astronomers to see beyond surrounding clouds of dust and gas to the blue colour of the disc in infrared light. The observations were done with the FORS and ISAAC instruments on one of the 8.2-m Unit Telescopes of ESO's Very Large Telescope, located in the Atacama

  19. On the evolution of the protolunar disc.

    PubMed

    Ward, William R

    2014-09-13

    The structure and viscous evolution of a post-impact, protolunar disc is examined. The equations for a silicate disc in two-phase (vapour-liquid) equilibrium are employed to derive an analytical solution to vertical structure. Both a vertically mixed phase disc and a stratified disc, where a magma layer exists in the mid-plane surrounded by a vapour reservoir, are considered. The former largely reproduces the low gas mass fraction, x≪1, profiles of the disc described in earlier literature that proposed that the disc would hover on the brink of gravitational instability. In the latter, the vapour layer has x∼1 and is generally gravitationally stable, while the magma layer is vigorously unstable. The viscous evolution of the stratified model is then explored. Initially, the disc quickly settles to a quasi-steady state with a vapour reservoir containing the majority of the disc mass. The magma layer viscously spreads on a time scale of approximately 3-4 years, during which vapour continuously condenses into droplets that settle to the mid-plane, maintaining the magma surface density in spite of disc spreading. Material flowing inwards is accreted by the Earth; material flowing outwards past the Roche boundary can become incorporated into accreting moonlets. This evolution persists until the vapour reservoir is depleted in approximately 50-100 years, depending on its initial mass. PMID:25114314

  20. The quiescent phase of galactic disc growth

    NASA Astrophysics Data System (ADS)

    Aumer, Michael; Binney, James; Schönrich, Ralph

    2016-07-01

    We perform a series of controlled N-body simulations of growing disc galaxies within non-growing, live dark matter haloes of varying mass and concentration. Our initial conditions include either a low-mass disc or a compact bulge. New stellar particles are continuously added on near-circular orbits to the existing disc, so spiral structure is continuously excited. To study the effect of combined spiral and giant molecular cloud (GMC) heating on the discs, we introduce massive, short-lived particles that sample a GMC mass function. An isothermal gas component is introduced for a subset of the models. We perform a resolution study and vary parameters governing the GMC population, the histories of star formation and radial scale growth. Models with GMCs and standard values for the disc mass and halo density provide the right level of self-gravity to explain the age-velocity dispersion relation of the solar neighbourhood (Snhd). GMC heating generates remarkably exponential vertical profiles with scaleheights that are radially constant and agree with observations of galactic thin discs. GMCs are also capable of significantly delaying bar formation. The amount of spiral-induced radial migration agrees with what is required for the metallicity distribution of the Snhd. However, in our standard models, the outward-migrating populations are not hot enough vertically to create thick discs. Thick discs can form in models with high baryon fractions, but the corresponding bars are too long, the young stellar populations too hot and the discs flare considerably.

  1. The quiescent phase of galactic disc growth

    NASA Astrophysics Data System (ADS)

    Aumer, Michael; Binney, James; Schönrich, Ralph

    2016-04-01

    We perform a series of controlled N-body simulations of growing disc galaxies within non-growing, live dark matter haloes of varying mass and concentration. Our initial conditions include either a low-mass disc or a compact bulge. New stellar particles are continuously added on near-circular orbits to the existing disc, so spiral structure is continuously excited. To study the effect of combined spiral and giant molecular cloud (GMC) heating on the discs we introduce massive, short-lived particles that sample a GMC mass function. An isothermal gas component is introduced for a subset of the models. We perform a resolution study and vary parameters governing the GMC population, the histories of star formation and radial scale growth. Models with GMCs and standard values for the disc mass and halo density provide the right level of self-gravity to explain the age velocity dispersion relation of the Solar neighbourhood (Snhd). GMC heating generates remarkably exponential vertical profiles with scaleheights that are radially constant and agree with observations of galactic thin discs. GMCs are also capable of significantly delaying bar formation. The amount of spiral induced radial migration agrees with what is required for the metallicity distribution of the Snhd. However, in our standard models the outward migrating populations are not hot enough vertically to create thick discs. Thick discs can form in models with high baryon fractions, but the corresponding bars are too long, the young stellar populations too hot and the discs flare considerably.

  2. Qualifying stem cell sources: how to overcome potential pitfalls in regenerative medicine?

    PubMed

    Reinke, Simon; Dienelt, Anke; Blankenstein, Antje; Duda, Georg N; Geissler, Sven

    2016-01-01

    Regenerative medicine aims to replace lost cells and to restore damaged tissues and organs by either tissue-engineering approaches or stimulation of endogenous processes. Due to their biological properties, stem cells promise to be an effective source for such strategies. Especially adult multipotent stem cells (ASCs) are believed to be applicable in a broad range of therapies for the treatment of multifactorial diseases or age-related degeneration, although the molecular and cellular mechanisms underlying their regenerative function are often hardly described. Moreover, in some demanding clinical situations their efficiency remains limited. Thus, a basic understanding of ASCs regenerative function, their complex interplay with their microenvironment and how compromising conditions interfere with their efficiency is mandatory for any regenerative strategy. Concerning this matter, the impact of patient-specific constraints are often underestimated in research projects and their influence on the study results disregarded. Thus, researchers are urgently depending on well-characterized tissue samples or cells that are connected with corresponding donor information, such as secondary diseases, medication. Here, we outline principle pitfalls during experimental studies using human samples, and describe a potential strategy to overcome these challenges by establishing a core unit for cell and tissue harvesting. This facility aims to bridge the gap between clinic and research laboratories by the provision of a direct link to the clinical operating theatres. Such a strategy clearly supports basic and clinical research in the conduct of their studies and supplies highly characterized human samples together with the corresponding donor information. PMID:24919850

  3. Cultural Diversity in Nursing Education: Perils, Pitfalls, and Pearls

    PubMed Central

    Bednarz, Hedi; Schim, Stephanie; Doorenbos, Ardith

    2010-01-01

    Increasing diversity in the classroom challenges nursing educators to identify issues that complicate teaching (perils), analyze barriers for themselves and their students (pitfalls), and select new strategies for working with nontraditional students (pearls). This article identifies concerns arising from attitudes and values within nursing and common approaches to diversity education, and then discusses key issues in nursing education that relate to human nature, culture, faculty workload, and student demographics. Finally, some strategies are proposed for increasing the effectiveness of professional preparation with diverse students through a focus on culturally congruent education and development of faculty cultural competence. PMID:20143759

  4. [Pitfalls in the diagnosis of occult elbow fractures in children].

    PubMed

    Courvoisier, A; Calvelli, N; Bourgeois, E; Eid, A; Griffet, J

    2016-08-01

    Elbow injuries are frequent but occult fractures are difficult to diagnose on x-rays. However, any delay in the diagnosis may severely impair the prognosis of some fractures. Simple tips may help the clinician read x-rays properly and avoid the classical pitfalls of elbow injuries in children. The chronology of appearance of ossification nuclei around the elbow is important to distinguish normal features from abnormality. Drawing simple geometric constructions on the x-rays may clarify most occult elbow fractures in children. PMID:27345552

  5. Artifacts and pitfalls in shoulder magnetic resonance imaging*

    PubMed Central

    Marcon, Gustavo Felix; Macedo, Tulio Augusto Alves

    2015-01-01

    Magnetic resonance imaging has revolutionized the diagnosis of shoulder lesions, in many cases becoming the method of choice. However, anatomical variations, artifacts and the particularity of the method may be a source of pitfalls, especially for less experienced radiologists. In order to avoid false-positive and false-negative results, the authors carried out a compilation of imaging findings that may simulate injury. It is the authors’ intention to provide a useful, consistent and comprehensive reference for both beginner residents and skilled radiologists who work with musculoskeletal magnetic resonance imaging, allowing for them to develop more precise reports and helping them to avoid making mistakes. PMID:26379323

  6. Avoiding pitfalls in simulating real-time computer systems

    NASA Technical Reports Server (NTRS)

    Smith, R. S.

    1984-01-01

    The software simulation of a computer target system on a computer host system, known as an interpretive computer simulator (ICS), functionally models and implements the action of the target hardware. For an ICS to function as efficiently as possible and to avoid certain pitfalls in designing an ICS, it is important that the details of the hardware architectural design of both the target and the host computers be known. This paper discusses both host selection considerations and ICS design features that, without proper consideration, could make the resulting ICS too slow to use or too costly to maintain and expand.

  7. The seven common pitfalls of customer service in hospitals.

    PubMed

    Domingo, Rene T

    2015-01-01

    Operating simultaneously like a repair shop, prison, and hotel, hospitals are prone to seven common pitfalls in customer service. Patient care is often fragmented, inscrutable, inflexible, insensitive, reactive, myopic, and unsafe. Hospitals are vying to be more high-tech, rather than high-touch even though staff engagement with patients rather than facilities and equipment strongly influence patient satisfaction. Unless processes, policies, and people are made customer-centered, the high quality of the hospital's human and hardware resources will not translate into high patient satisfaction and patient loyalty. PMID:26058286

  8. Imaging of facial nerve schwannomas: diagnostic pearls and potential pitfalls

    PubMed Central

    Mundada, Pravin; Purohit, Bela Satish; Kumar, Tahira Sultana; Tan, Tiong Yong

    2016-01-01

    Schwannomas are uncommon in the facial nerve and account for less than 1% of tumors of temporal bone. They can involve one or more than one segment of the facial nerve. The clinical presentations and the imaging appearances of facial nerve schwannomas are influenced by the topographical anatomy of the facial nerve and vary according to the segment(s) they involve. This pictorial essay illustrates the imaging features of facial nerve schwannomas according to their various anatomical locations and also reviews the pertinent differential diagnoses and potential diagnostic pitfalls. PMID:26712680

  9. Fluorescent Proteins in Cellular Organelles: Serious Pitfalls and Some Solutions

    PubMed Central

    Costantini, Lindsey M.

    2013-01-01

    Fluorescent proteins (FPs) have been powerful tools for cell biologists for over 15 years. The large variety of FPs available rarely comes with an instruction manual or a warning label. The potential pitfalls of the use of FPs in cellular organelles represent a significant concern for investigators. FPs generally did not evolve in the often distinctive physicochemical environments of subcellular organelles. In organelles, FPs can misfold, go dark, and even distort organelle morphology. In this minireview, we describe the issues associated with FPs in organelles and provide solutions to enable investigators to better exploit FP technology in cells. PMID:23971632

  10. Principles and Pitfalls: a Guide to Death Certification

    PubMed Central

    Brooks, Erin G.; Reed, Kurt D.

    2015-01-01

    Death certificates serve the critical functions of providing documentation for legal/administrative purposes and vital statistics for epidemiologic/health policy purposes. In order to satisfy these functions, it is important that death certificates be filled out completely, accurately, and promptly. The high error rate in death certification has been documented in multiple prior studies, as has the effectiveness of educational training interventions at mitigating errors. The following guide to death certification is intended to illustrate some basic principles and common pitfalls in electronic death registration with the goal of improving death certification accuracy. PMID:26185270

  11. Epidemiological designs for vaccine safety assessment: methods and pitfalls.

    PubMed

    Andrews, Nick

    2012-09-01

    Three commonly used designs for vaccine safety assessment post licensure are cohort, case-control and self-controlled case series. These methods are often used with routine health databases and immunisation registries. This paper considers the issues that may arise when designing an epidemiological study, such as understanding the vaccine safety question, case definition and finding, limitations of data sources, uncontrolled confounding, and pitfalls that apply to the individual designs. The example of MMR and autism, where all three designs have been used, is presented to help consider these issues. PMID:21985898

  12. Grant-Writing Pearls and Pitfalls: Maximizing Funding Opportunities.

    PubMed

    Liu, Jeffrey C; Pynnonen, Melissa A; St John, Maie; Rosenthal, Eben L; Couch, Marion E; Schmalbach, Cecelia E

    2016-02-01

    This invited article reviews the grant process to include the following objectives: (1) to provide an understanding of otolaryngology funding mechanisms in the context of career progression; (2) to outline key components of a well-written grant; (3) to highlight vital members of a successful research team, with emphasis on the mentor-mentee relationship; and (4) to clarify grant scoring with emphasis on common pitfalls to avoid. Current otolaryngology funding mechanisms and up-to-date resources are provided. The review is aimed to assist otolaryngology residents, faculty new to the grant process, as well as experienced researchers striving to improve their grant review scores. PMID:26626133

  13. Total Disc Arthroplasty for Treating Lumbar Degenerative Disc Disease

    PubMed Central

    2015-01-01

    Study Design Lumber disc arthroplasty is a technological advancement that has occurred in the last decade to treat lumbar degenerative disk diseases. Purpose The aim of this retrospective study was to establish the impact and outcomes of managing patients with lumbar degenerative disk disease who have been treated with lumbar total disc arthroplasty (TDA). Overview of Literature Several studies have shown promising results following this surgery. Methods We reviewed the files of 104 patients at the Department of Neurosurgery in Colmar (France) who had been operated on by lumbar spine arthroplasty (Prodisc) between April 2002 and October 2008. Results Among the 104 patients, 67 were female and 37 were male with an average age of 33.1 years. We followed the cases for a mean of 20 months. The most frequent level of discopathy was L4-L5 with 62 patients (59.6%) followed by L5-S1 level with 52 patients (50%). Eighty-three patients suffered from low back pain, 21 of which were associated with radiculopathy. The status of 82 patients improved after surgery according to the Oswestry Disability Index score, and 92 patients returned to work. Conclusions The results indicate that TDA is a good alternative treatment for lumbar spine disk disease, particularly for patients with disabling and chronic low back pain. This technique contributes to improve living conditions with correct patient selection for surgery. PMID:25705336

  14. Development of injectable hydrogels for nucleus pulposus replacement

    NASA Astrophysics Data System (ADS)

    Thomas, Jonathan D.

    Intervertebral disc degeneration has been reported as the underlying cause for 75% of cases of lower back pain and is marked by dehydration of the nucleus pulposus within the intervertebral disc. There have been many implant designs to replace the nucleus pulposus. Some researchers have proposed the replacement of the nucleus pulposus with hydrogel materials. The insertion of devices made from these materials further compromises the annulus of the disc. An ideal nucleus replacement could be injected into the disc space and form a solid in vivo. However, injectable replacements using curing elastomers and thermoplastic materials are not ideal because of the potentially harmful exothermic heat evolved from their reactions and the toxicity of the reactants used. We propose a hydrogel system that can be injected as a liquid at 25°C and solidified to yield a hydrogel within the intervertebral disc at 37°C. In aqueous solutions, these polymers have Lower Critical Solution Temperatures (LCST) between 25-37°C, making them unique candidate materials for this application. Poly(N-isopropylacrylamide) (PNIPAAm) is the most widely studied LCST polymer due to its drastic transition near body temperature. However, by itself, pure PNIPAAm forms a hydrogel that has low water content and can readily undergo plastic deformation. To increase the water content and impart elasticity to PNIPAAm hydrogels, grafted and branched hydrogel systems were created that incorporated the thermogelling PNIPAAm and hydrophilic poly(ethylene glycol) (PEG). In this research, the effects of polymer composition and monomer to initiator ratio, which controls polymer MW, on the in vitro swelling properties (mass, chemical, and compressive mechanical stability) of hydrogels formed from aqueous solutions of these polymers were evaluated. Immersion studies were also conducted in solutions to simulate the osmotic environment of the nucleus pulposus. The effects of repeated compression and unloading cycles

  15. Pharmacological mydriasis and optic disc examination

    PubMed Central

    Kirwan, J.; Gouws, P.; Linnell, A.; Crowston, J.; Bunce, C.

    2000-01-01

    AIM—To determine whether pharmacological mydriasis leads to a significant difference in interobserver agreement of optic disc measurement compared with examination without mydriasis.
METHOD—A cross sectional study was performed with a pair of observers examining the optic disc of two randomised groups of patients, one group before diagnostic mydriasis, and the other afterwards. Horizontal and vertical disc diameters and cup/disc ratios were measured with a 78 dioptre lens. The study was repeated with another observer pair and two further groups of patients.
RESULTS—In study A 86 subjects were examined in total (52 without and 34 with mydriasis). In study B 87 subjects were examined (45 without and 42 with mydriasis). The 95% limits of agreement of the cup/disc ratio measurement differences were significantly larger without mydriasis (p<0.001 for all studies (F test)). For both studies examination after mydriasis gave significantly greater agreement for vertical and horizontal cup/disc ratios. The cases with good agreement (0.1 difference or better) for vertical cup/disc ratios were 37/52 (72%) and 34 /45 (76%) without mydriasis and 33/34 (97%) and 40/42 (95%) respectively with mydriasis. Similar differences were recorded for horizontal cup/disc ratios. Disc diameter measurement results showed similar differences in study A but were not affected by mydriasis in study B.
CONCLUSIONS—Examination of the optic disc without pharmacological mydriasis gives significantly poorer interobserver agreement. In this study, the mean 95% limits of agreement values for all cup/disc ratio values were 0.27 for examination without mydriasis and 0.13 for examination with mydriasis. A measure outside these limits would suggest a real difference. This study indicates that mydriasis is important for reproducible clinical examination in glaucoma.

 PMID:10906099

  16. Two-Year Results of a Randomized Controlled Clinical Trial Comparing ProDisc-C and Anterior Cervical Discectomy and Fusion

    PubMed Central

    Janssen, Michael E.; Odum, Susan M.; Gottlieb, Jon R.; Spector, Leo R.; Darden, Bruce V.

    2008-01-01

    Background Anterior cervical discectomy and fusion (ACDF) is a well-accepted procedure for the treatment of cervical radiculopathy. Hilibrand et al. reported that adjacent segment disease is known to occur at a rate of 2.9% per year after cervical fusion. Developers of cervical disc replacements postulate that maintaining more normal motion may reduce the rate of adjacent segment disease. The purpose of this study was to compare the 2-year efficacy and safety of ACDF and cervical total disc replacement surgery. Methods Eighty-seven patients from 2 sites of this 13 multicenter trial were randomized to treatment with either ACDF or cervical disc replacement surgery with the ProDisc-C (Synthes, Inc., West Chester, Pennsylvania) implant. Patient outcomes were assessed via neck disability index (NDI), visual analog pain scale (VAS), and health survey SF-36 (QualityMetric, Lincoln, Rhode Island). Forty-three patients were treated with ACDF using allograft and plating, and 44 were treated with cervical disc replacement. The average age was 44 (23 to 61) years. All surgical procedures were single level. Results At all measured time points, both groups showed statistically significant improvement over their preoperative baseline with regard to NDI, VAS arm and neck pain levels, SF-36 mental composite score (MCS), and physical composite score (PCS) (P < .05). At 24 months, the disc replacement group showed results equivalent to the ACDF group with regard to NDI, VAS arm and neck pain, and SF-36 MCS. At 24 months, the disc replacement group showed significantly greater improvement in SF- 36 PCS as compared to the ACDF group (P = .0359). Of note, there was a trend toward greater patient satisfaction in the disc replacement group as compared to the ACDF group (83% versus 71%, P = .144). Conclusions This study indicates that the tested disc replacement device achieves 2-year results ranging from equivalent to superior in comparison to ACDF in the treatment of symptomatic

  17. Quantitative Pfirrmann Disc Degeneration Grading System to Overcome the Limitation of Pfirrmann Disc Degeneration Grade

    PubMed Central

    2016-01-01

    Objective Pfirrmann disc degeneration grade is one of morphologic disc degeneration grading system and it was reliable on routine T2-weighted magnetic resonance (MR) images. The purpose of this study was to evaluate the agreement of Pfirrmann disc degeneration grade, and check the alternative technique of disc degeneration grading system. Methods Fifteen volunteers (4 medical doctors related to spinal disease, 2 medical doctors not related to spinal disease, 6 nurses in spinal hospital, and 3 para-medicines) were included in this study. Three different digitalized MR images were provided all volunteers, and they checked Pfirrmann disc degeneration grade of each disc levels after careful listening to explanation. Indeed, all volunteers checked the signal intensity of disc degeneration at the points of nucleus pulposus (NP), disc membrane, ligaments, fat, and air to modify the quantitative Pfirrmann disc degeneration grade. Results Total 225 grade results of Pfirrmann disc degeneration grade and 405 signal intensity results of quantitative Pfirrmann disc degeneration grade were analyzed. Average interobserver agreement was "moderate (mean±standard deviation, 0.575±0.251)" from poor to excellent. Completely agreed levels of Pfirrmann disc degeneration grade were only 4 levels (26.67%), and the disagreement levels were observed in 11 levels; two different grades in 8 levels (53.33%) and three different grades in 3 levels (20%). Quantitative Pfirrmann disc degeneration showed relatively cluster distribution with the interobserver deviations of 0.41-1.56 at the ratio of NP and disc membrane, and it showed relatively good cluster and distribution indicating that the proposed grading system has good discrimination ability. Conclusion Pfirrmann disc degeneration grade showed the limitation of different interobserver results, but this limitation could be overcome by using quantitative techniques of MR signal intensity. Further evaluation is needed to access its advantage

  18. Hormone Replacement Therapy

    MedlinePlus

    ... before and during menopause, the levels of female hormones can go up and down. This can cause ... hot flashes and vaginal dryness. Some women take hormone replacement therapy (HRT), also called menopausal hormone therapy, ...

  19. Hip replacement - discharge

    MedlinePlus

    ... a hip replacement and need antibiotics before any dental work. When to Call Your Doctor Call your health care provider if you have: A sudden increase in pain Chest pain or shortness of breath Frequent urination ...

  20. Replacing Arizona's Roofs.

    ERIC Educational Resources Information Center

    Fickes, Michael

    2000-01-01

    Discusses the Arizona statewide mandate to spend $500 million to repair or replace roofs in its public school system. Data from the state's evaluation process are provided, including how the state will fund the project. (GR)

  1. Knee joint replacement

    MedlinePlus

    The results of a total knee replacement are often excellent. The operation relieves pain for most people. Most people do not need help walking after they fully recover. Most artificial knee joints last 10 ...

  2. Hip joint replacement - slideshow

    MedlinePlus

    ... this page: //medlineplus.gov/ency/presentations/100006.htm Hip joint replacement - series—Normal anatomy To use the sharing ... to slide 5 out of 5 Overview The hip joint is made up of two major parts: the ...

  3. Replacing a Missing Tooth

    MedlinePlus

    ... majority of patients with clefts will require full orthodontic treatment, especially if the cleft has passed through ... later replacement of the missing lateral incisor. During orthodontic treatment, an artificial tooth may be attached to ...

  4. Knee joint replacement - slideshow

    MedlinePlus

    ... page: //medlineplus.gov/ency/presentations/100088.htm Knee joint replacement - series—Normal anatomy To use the sharing ... of 4 Overview The knee is a complex joint. It contains the distal end of the femur ( ...

  5. Kidney Replacement Therapy

    MedlinePlus

    ... their function with either dialysis or a transplant. Dialysis Dialysis, the more common form of kidney-replacement ... the result of diabetes, not of hemodialysis. Peritoneal dialysis Another form of dialysis is called peritoneal dialysis. ...

  6. Viscoelastic Disc Arthroplasty Provides Superior Back and Leg Pain Relief in Patients with Lumbar Disc Degeneration Compared to Anterior Lumbar Interbody Fusion

    PubMed Central

    Rischke, Burkhard; Smith, Eric

    2015-01-01

    Background Lumbar disc degeneration (LDD) is one of the most frequently diagnosed spinal diseases. The symptoms these disorders cause are anticipated to increase as the population in Western countries ages. Purpose Compare back and leg pain alleviation in patients with LDD and a viscoelastic disc prosthesis documented in the SWISSspine registry versus patients with anterior lumbar interbody fusion documented in the Spine Tango registry. Study Design Prospectively collected clinical and outcome data in two independent spine registries. Outcome Measures were back and leg pain relief on 0 to 10 numerical rating scales. Materials and Methods The analysis included a single surgeon series of 48 patients with viscoelastic total disc replacement (VTDR) from the SWISSspine registry which were compared to 131 patients with anterior lumbar interbody fusion (ALIF) from the Spine Tango registry. Two linear multivariate regression models were built to assess the associations of patient characteristics with back and leg pain relief. The following covariates were included in the models: patient age and sex, disc herniation as additional diagnosis, number of treated segments, level of treated segment, treatment type (VTDR, ALIF), preoperative back and leg pain levels and follow-up interval. Results Both models showed VTDR to be associated with significantly higher back (2.76 points; 95% confidence interval (CI) 1.78 - 3.73; p < 0.001) and leg pain (2.12 points; 95% CI 1.12 to 3.13; p < 0.001) relief than ALIF. Other influential factors for higher back pain relief were female sex compared with male sex (1.03 additional points; 95% CI 0.27 to 1.78; p = 0.008), monosegmental surgery compared with bisegmental surgery (1.02 additional points; 95% CI 0.21 to 1.83; p = 0.014), and higher back pain at baseline (0.87 points additional pain relief per level of preoperative back pain; 95% CI 0.70 to 1.03; p < 0.001). Other influential factors for leg pain relief were monosegmental surgery (0

  7. Use NASA GES DISC Data in ArcGIS

    NASA Technical Reports Server (NTRS)

    Yang, Wenli; Pham, Long B.; Kempler, Steve

    2015-01-01

    This presentation describes GIS relevant data at NASA Goddard Earth Sciences Data and Information Services Center (GES DISC), GES DISC Services and Support for GIS Users, and use cases of GES DISC data in ArcGIS.

  8. Changes in disc herniation after CT-guided Percutaneous Laser Disc Decompression (PLDD): MR findings

    NASA Astrophysics Data System (ADS)

    Brat, Hugues G.; Bouziane, Tarik; Lambert, Jean; Divano, Luisa

    2004-09-01

    The aim of Percutaneous Laser Disc Decompression (PLDD) is to vaporize a small portion of the nucleus pulposus. Clinical efficacy of this technique is largely proven. However, time-evolution of intervertebral disc and its hernia after PLDD is not known. This study analyses changes in disc herniation and its native intervertebral disc at a mean follow-up of 7.5 months after PLDD in asymptomatic patients. Main observations at MRI are appearance of a high signal on T2WI in the hernia in 59%, shrinking of the hernia in 66% and overall stability of disc height.

  9. Assessment of Magnetic Resonance Imaging Artifact Following Cervical Total Disc Arthroplasty

    PubMed Central

    Fayyazi, Amir H.; Taormina, Jennifer; Svach, David; Stein, Jeff

    2015-01-01

    Background Cervical disc arthroplasty has become a technique for the treatment of cervical degenerative disc disease. Clinically, the need to accurately assess the neural elements at the operative and adjacent levels is critical postoperatively. The purpose of this study was to quantitatively and qualitatively measure the amount of MRI artifact produced by various cervical total disc replacements. Methods T1 and T2-weighted turbo spin-echo MRI sequences were collected on the cervical spine (C2-T1) of a 68 year-old unembalmed male cadaver. A discectomy was performed at C5-6, followed by successive implantation of six different total disc replacements. The scans were quantitatively evaluated by three of the authors. The volume of artifact was measured using image analysis software. Qualitative analysis of the adjacent and index neural elements was performed. Results The artifact in the T2 weighted images was noted to be 58.6±7.3 cm3 for Prestige ST, 14.2±1.3 cm3 for ProDisc-C, 7.5±0.8 cm3 for Discover, 8.0±0.3 cm3 for Prestige LP, 6.6±0.7 cm3 for Bryan, and 7.3±0.6 cm3 for ProDisc-C titanium prototype. Acceptable intraobserver and excellent interobsever correlation was demonstrated using Pearson Correlation and Concordance Correlation Coefficient analysis. The adjacent and implanted level neural elements (spinal cord and neuroforamina) were easily visualized on the T2 weighted images after the implantation of titanium devices (ProDisc-C titanium prototype, Discover, Prestige LP and Bryan). After implantation of a cobalt chrome implant (ProDisc-C), the adjacent level neural elements were easily visualized but the implanted level could not be fully visualized due to distortion of the images. The quality of the distortion was least favorable after the implantation of the stainless steel implant (Prestige ST), where neither the adjacent nor the index level could be fully visualized. Conclusion The volume of the artifact seen following cervical total disc

  10. Human Rhabdomyosarcoma Cell Lines for Rhabdomyosarcoma Research: Utility and Pitfalls

    PubMed Central

    Hinson, Ashley R. P.; Jones, Rosanne; Crose, Lisa E. S.; Belyea, Brian C.; Barr, Frederic G.; Linardic, Corinne M.

    2013-01-01

    Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma of childhood and adolescence. Despite intergroup clinical trials conducted in Europe and North America, outcomes for high risk patients with this disease have not significantly improved in the last several decades, and survival of metastatic or relapsed disease remains extremely poor. Accrual into new clinical trials is slow and difficult, so in vitro cell-line research and in vivo xenograft models present an attractive alternative for preclinical research for this cancer type. Currently, 30 commonly used human RMS cell lines exist, with differing origins, karyotypes, histologies, and methods of validation. Selecting an appropriate cell line for RMS research has important implications for outcomes. There are also potential pitfalls in using certain cell lines including contamination with murine stromal cells, cross-contamination between cell lines, discordance between the cell line and its associated original tumor, imposter cell lines, and nomenclature errors that result in the circulation of two or more presumed unique cell lines that are actually from the same origin. These pitfalls can be avoided by testing for species-specific isoenzymes, microarray analysis, assays for subtype-specific fusion products, and short tandem repeat analysis. PMID:23882450

  11. Pitfalls of CITES implementation in Nepal: a policy gap analysis.

    PubMed

    Dongol, Yogesh; Heinen, Joel T

    2012-08-01

    Implementation of policy involves multiple agencies operating at multiple levels in facilitating processes and actions to accomplish desired results. The Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) was developed and implemented to regulate and control international wildlife trade, but violations of the agreement are widespread and growing worldwide, including in Nepal. This study attempts to understand how domestic CITES policies are translated into action and what effect actions and processes have on compliance. In doing so, this study provides insights into the implementation and enforcement pitfalls of national legislation that explain CITES violations in Nepal. Primarily, we used 26 key informants interviews to learn opinions of experts, and the grounded theory approach for further qualitative data analysis. In addition, we used Najman's (1995) policy implementation analysis framework to explain gaps. Many interrelated variables in the content of the policy, commitment and capacity of the agencies, the roles of clients and coalitions and contextual issues were observed. Variables that emerged suggest pitfalls in the regulatory policy represented by low probability of detection, arrest and punishment. Moreover, redistributive policies in buffer zones of protected areas are needed into perpetuity to benefit locals. Also, conservation organizations' support for building public and political salience is imperative. PMID:22706477

  12. Pitfalls of CITES Implementation in Nepal: A Policy Gap Analysis

    NASA Astrophysics Data System (ADS)

    Dongol, Yogesh; Heinen, Joel T.

    2012-08-01

    Implementation of policy involves multiple agencies operating at multiple levels in facilitating processes and actions to accomplish desired results. The Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) was developed and implemented to regulate and control international wildlife trade, but violations of the agreement are widespread and growing worldwide, including in Nepal. This study attempts to understand how domestic CITES policies are translated into action and what effect actions and processes have on compliance. In doing so, this study provides insights into the implementation and enforcement pitfalls of national legislation that explain CITES violations in Nepal. Primarily, we used 26 key informants interviews to learn opinions of experts, and the grounded theory approach for further qualitative data analysis. In addition, we used Najman's (1995) policy implementation analysis framework to explain gaps. Many interrelated variables in the content of the policy, commitment and capacity of the agencies, the roles of clients and coalitions and contextual issues were observed. Variables that emerged suggest pitfalls in the regulatory policy represented by low probability of detection, arrest and punishment. Moreover, redistributive policies in buffer zones of protected areas are needed into perpetuity to benefit locals. Also, conservation organizations' support for building public and political salience is imperative.

  13. Rapid radiative clearing of protoplanetary discs

    NASA Astrophysics Data System (ADS)

    Haworth, Thomas J.; Clarke, Cathie J.; Owen, James E.

    2016-04-01

    The lack of observed transition discs with inner gas holes of radii greater than ˜50 au implies that protoplanetary discs dispersed from the inside out must remove gas from the outer regions rapidly. We investigate the role of photoevaporation in the final clearing of gas from low mass discs with inner holes. In particular, we study the so-called `thermal sweeping' mechanism which results in rapid clearing of the disc. Thermal sweeping was originally thought to arise when the radial and vertical pressure scalelengths at the X-ray heated inner edge of the disc match. We demonstrate that this criterion is not fundamental. Rather, thermal sweeping occurs when the pressure maximum at the inner edge of the dust heated disc falls below the maximum possible pressure of X-ray heated gas (which depends on the local X-ray flux). We derive new critical peak volume and surface density estimates for rapid radiative clearing which, in general, result in rapid dispersal happening less readily than in previous estimates. This less efficient clearing of discs by X-ray driven thermal sweeping leaves open the issue of what mechanism (e.g. far-ultraviolet heating) can clear gas from the outer disc sufficiently quickly to explain the non-detection of cold gas around weak line T Tauri stars.

  14. The inner cavity of the circumnuclear disc

    NASA Astrophysics Data System (ADS)

    Blank, M.; Morris, M. R.; Frank, A.; Carroll-Nellenback, J. J.; Duschl, W. J.

    2016-06-01

    The circumnuclear disc (CND) orbiting the Galaxy's central black hole is a reservoir of material that can ultimately provide energy through accretion, or form stars in the presence of the black hole, as evidenced by the stellar cluster that is presently located at the CND's centre. In this paper, we report the results of a computational study of the dynamics of the CND. The results lead us to question two paradigms that are prevalent in previous research on the Galactic Centre. The first is that the disc's inner cavity is maintained by the interaction of the central stellar cluster's strong winds with the disc's inner rim, and secondly, that the presence of unstable clumps in the disc implies that the CND is a transient feature. Our simulations show that, in the absence of a magnetic field, the interaction of the wind with the inner disc rim actually leads to a filling of the inner cavity within a few orbital time-scales, contrary to previous expectations. However, including the effects of magnetic fields stabilizes the inner disc rim against rapid inward migration. Furthermore, this interaction causes instabilities that continuously create clumps that are individually unstable against tidal shearing. Thus the occurrence of such unstable clumps does not necessarily mean that the disc is itself a transient phenomenon. The next steps in this investigation are to explore the effect of the magnetorotational instability on the disc evolution and to test whether the results presented here persist for longer time-scales than those considered here.

  15. D-Zero Cryostat Supplemental Rupture Disc

    SciTech Connect

    Mulholland, G.T.; /Fermilab

    1987-08-03

    The common relief and rupture disc vent line requires a double disc assembly with vented interspace for accurate disc burst pressures. The first disc must take pump and purge vacuum loading, but be set to operate at 110% of the MAWP, 18.3 psig (ASME code). The available solution is 18.3 psig with a burst tolerance of +/- psig. The interspace should be locally vented by a flow limiting vent valve to decouple the vent line backpressure from the vessel rupture disc. The second disc must take the worst case vent line backpressure, the steady state value found in D-Zero engineering note 3740.000-EN-63 with all three cryostats simultaneously venting at the fire condition into the 4-inch x 6-inch and 6-inch x 8-inch sections. This value is less than 2 psid. The maximum rupture value for the second disc must be less than the minimum rupture value for the first disc less 2 psid i.e. < 16.3.

  16. Floquet analysis in accretion disc dynamics

    NASA Astrophysics Data System (ADS)

    Tamburini, F.; Bianchini, A.

    2002-01-01

    Floquet analysis is proposed to analyze the evolution of exponentially growing modes of the local instabilities in accretion discs of CVs induced by perturbations in the velocity field. Both the stability of the disc and the deviation of the Reynolds number are described by the Floquet exponents μj of the perturbations, which represent Landau's modes of the fluid.

  17. 46 CFR 64.61 - Rupture disc.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 2 2014-10-01 2014-10-01 false Rupture disc. 64.61 Section 64.61 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING MARINE PORTABLE TANKS AND CARGO HANDLING SYSTEMS Pressure Relief Devices and Vacuum Relief Devices for MPTs § 64.61 Rupture disc. If a rupture...

  18. 46 CFR 64.61 - Rupture disc.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 2 2013-10-01 2013-10-01 false Rupture disc. 64.61 Section 64.61 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING MARINE PORTABLE TANKS AND CARGO HANDLING SYSTEMS Pressure Relief Devices and Vacuum Relief Devices for MPTs § 64.61 Rupture disc. If a rupture...

  19. 46 CFR 64.61 - Rupture disc.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 2 2011-10-01 2011-10-01 false Rupture disc. 64.61 Section 64.61 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING MARINE PORTABLE TANKS AND CARGO HANDLING SYSTEMS Pressure Relief Devices and Vacuum Relief Devices for MPTs § 64.61 Rupture disc. If a rupture...

  20. 46 CFR 64.61 - Rupture disc.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Rupture disc. 64.61 Section 64.61 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING MARINE PORTABLE TANKS AND CARGO HANDLING SYSTEMS Pressure Relief Devices and Vacuum Relief Devices for MPTs § 64.61 Rupture disc. If a rupture...

  1. 46 CFR 64.61 - Rupture disc.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 2 2012-10-01 2012-10-01 false Rupture disc. 64.61 Section 64.61 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING MARINE PORTABLE TANKS AND CARGO HANDLING SYSTEMS Pressure Relief Devices and Vacuum Relief Devices for MPTs § 64.61 Rupture disc. If a rupture...

  2. Disc cell senescence in intervertebral disc degeneration: Causes and molecular pathways

    PubMed Central

    Feng, Chencheng; Liu, Huan; Yang, Minghui; Zhang, Yang; Huang, Bo; Zhou, Yue

    2016-01-01

    ABSTRACT The accumulation of senescent disc cells in degenerative intervertebral disc (IVD) suggests the detrimental roles of cell senescence in the pathogenesis of intervertebral disc degeneration (IDD). Disc cell senescence decreased the number of functional cells in IVD. Moreover, the senescent disc cells were supposed to accelerate the process of IDD via their aberrant paracrine effects by which senescent cells cause the senescence of neighboring cells and enhance the matrix catabolism and inflammation in IVD. Thus, anti-senescence has been proposed as a novel therapeutic target for IDD. However, the development of anti-senescence therapy is based on our understanding of the molecular mechanism of disc cell senescence. In this review, we focused on the molecular mechanism of disc cell senescence, including the causes and various molecular pathways. We found that, during the process of IDD, age-related damages together with degenerative external stimuli activated both p53-p21-Rb and p16-Rb pathways to induce disc cell senescence. Meanwhile, disc cell senescence was regulated by multiple signaling pathways, suggesting the complex regulating network of disc cell senescence. To understand the mechanism of disc cell senescence better contributes to developing the anti-senescence-based therapies for IDD. PMID:27192096

  3. Simulations of the Galactic Centre Stellar Discs In a Warped Disc Origin Scenario

    NASA Astrophysics Data System (ADS)

    Ulubay-Siddiki, A.; Bartko, H.

    2012-07-01

    The Galactic Center (GC) hosts a population of young stars some of which seem to form a system of mutually inclined warped discs. While the presence of young stars in the close vicinity of the massive black hole is already problematic, their orbital configuration makes the situation even more puzzling. We present a possible warped disc origin scenario for these stars, which assumes an initially flat accretion disc which develops a warp through Pringle instability, or Bardeen-Petterson Effect. By working out the critical radii and the time scales involved, we argue that disc warping is plausible for GC parameters. We construct time evolution models for such discs considering the discs' self-gravity, and the torques exerted by the surrounding old star cluster. Our simulations suggest that the best agreement for a purely self-gravitating model is obtained for a disc-to-black hole mass ratio of Md/Mbh ~ 0.001.

  4. Dependence of optic disc parameters on disc area according to Heidelberg Retina Tomograph: Part II.

    NASA Astrophysics Data System (ADS)

    Machekhin, V.; Manaenkova, G.; Bondarenko, O.

    2007-05-01

    With the help of Heidelberg Retina Tomograph (HRT-II) optic disc parameters in 211 eyes of 115 healthy patients with refraction Em +/- 3,0 D and 96 eyes of 72 patients with myopia 3,5-14,0 D without any signs of glaucoma were studied. Analysis of optic disc parameters were carried out in 5 groups of patients according to disc area: less than 1,5 mm2, 1,5- 2,5 mm2, 2,5-3,0 mm2, 3,0-3,5 mm2 and more than 3,5 mm2. An accurate depending on disc area was revealed for all optic disc parameters in all sectors, which was manifested by increasing cup disc and rim disc (area and volume) and other parameters. We consider it is necessary to use the proper tables for right interpretation of received data for early diagnosis of glaucoma.

  5. Heterotopic ossification in cervical disc arthroplasty: Is it clinically relevant?

    PubMed Central

    Barbagallo, Giuseppe M.; Corbino, Leonardo A.; Olindo, Giuseppe; Albanese, Vincenzo

    2010-01-01

    Study design: Retrospective cohort study. Objective: To analyze the presence and clinical relevance of heterotopic ossification (HO) at 3 years mean follow-up. Methods: Thirty patients suffering from cervical radiculopathy and/or myelopathy treated with anterior disc replacement (ADR) were studied. HO was classified using the McAfee grading system. Range of motion was measured from flexion and extension x-rays. Short-form 36 and neck disability index (NDI) assessed functional outcome. Results: Forty-five prostheses were implanted in 30 patients with cervical radiculopathy and/or myelopathy, mean age 40.9 years. Nineteen patients received 1 level and 11 patients received multilevel disc replacement. The incidence rate of HO was 42.2% (19 levels). Segmental range of motion was ≥3° in 93.8% of patients with HO. There was no significant difference in functional scores between those who did and those who did not develop HO. Males tended to develop HO more frequently than females, though this was not statistically significant. The indication for surgery (soft disc hernia or spondylosis) was not associated with the formation of HO. Conclusions: Functional improvement is maintained despite the presence of HO following cervical disc arthroplasty. Indications for arthroplasty should not be halted by the risk of HO. Methods evaluation and class of evidence (CoE) Methodological principle: Study design:  Prospective cohort  Retrospective cohort •  Case-control  Case series Methods  Patients at similar point in course of treatment •  Follow-up ≥85%  Similarity of treatment protocols for patient groups •  Patients followed for long enough for outcomes to occur •  Control for extraneous risk factors* Evidence class: III *Authors must provide a description of robust baseline characteristics, and control for those that are potential prognostic factors. The definiton of the different classes of evidence is available on page 83. PMID:23544019

  6. About detection of precessing circumpulsar discs

    NASA Astrophysics Data System (ADS)

    Grimani, Catia

    2016-08-01

    Detections of circumpulsar discs and planetary systems through electromagnetic observations appear quite rare. In the case of PSR 1931+24 and B0656+14, the hypothesis of a precessing disc penetrating the pulsar light cylinder is found consistent with radio and gamma observations from these stars. Disc self-occultation and precession may affect electromagnetic measurements. We investigate here under which conditions gravitational waves generated by circumpulsar disc precession may be detected by the proposed second-generation space interferometers DECI-hertz Interferometer Gravitational Wave Observatory and Big Bang Observer. The characteristics of circumpulsar detectable precessing discs are estimated as a function of distance from the Solar system. Speculations on detection rates are presented.

  7. Hydrodynamic instability in warped astrophysical discs

    NASA Astrophysics Data System (ADS)

    Ogilvie, Gordon I.; Latter, Henrik N.

    2013-08-01

    Warped astrophysical discs are usually treated as laminar viscous flows, which have anomalous properties when the disc is nearly Keplerian and the viscosity is small: fast horizontal shearing motions and large torques are generated, which cause the warp to evolve rapidly, in some cases at a rate that is inversely proportional to the viscosity. However, these flows are often subject to a linear hydrodynamic instability, which may produce small-scale turbulence and modify the large-scale dynamics of the disc. We use a warped shearing sheet to compute the oscillatory laminar flows in a warped disc and to analyse their linear stability by the Floquet method. We find widespread hydrodynamic instability deriving from the parametric resonance of inertial waves. Even very small, unobservable warps in nearly Keplerian discs of low viscosity can be expected to generate hydrodynamic turbulence, or at least wave activity, by this mechanism.

  8. Strongly magnetized accretion discs require poloidal flux

    NASA Astrophysics Data System (ADS)

    Salvesen, Greg; Armitage, Philip J.; Simon, Jacob B.; Begelman, Mitchell C.

    2016-08-01

    Motivated by indirect observational evidence for strongly magnetized accretion discs around black holes, and the novel theoretical properties of such solutions, we investigate how a strong magnetization state can develop and persist. To this end, we perform local simulations of accretion discs with an initially purely toroidal magnetic field of equipartition strength. We demonstrate that discs with zero net vertical magnetic flux and realistic boundary conditions cannot sustain a strong toroidal field. However, a magnetic pressure-dominated disc can form from an initial configuration with a sufficient amount of net vertical flux and realistic boundary conditions. Our results suggest that poloidal flux is a necessary prerequisite for the sustainability of strongly magnetized accretion discs.

  9. Lumbar Epidural Varix Mimicking Disc Herniation

    PubMed Central

    Bursalı, Adem; Guvenal, Ahmet Burak; Yaman, Onur

    2016-01-01

    Lumbar radiculopathy is generally caused by such well-recognized entity as lumbar disc herniation in neurosurgical practice; however rare pathologies such as thrombosed epidural varix may mimic them by causing radicular symptoms. In this case report, we present a 26-year-old man with the complaint of back and right leg pain who was operated for right L4–5 disc herniation. The lesion interpreted as an extruded disc herniation preoperatively was found to be a thrombosed epidural varix compressing the nerve root preoperatively. The nerve root was decompressed by shrinking the lesion with bipolar thermocoagulation and excision. The patient's complaints disappeared in the postoperative period. Thrombosed lumbar epidural varices may mimic lumbar disc herniations both radiologically and clinically. Therefore, must be kept in mind in the differential diagnosis of lumbar disc herniations. Microsurgical techniques are mandatory for the treatment of these pathologies and decompression with thermocoagulation and excision is an efficient method. PMID:27446525

  10. Lumbar Epidural Varix Mimicking Disc Herniation.

    PubMed

    Bursalı, Adem; Akyoldas, Goktug; Guvenal, Ahmet Burak; Yaman, Onur

    2016-07-01

    Lumbar radiculopathy is generally caused by such well-recognized entity as lumbar disc herniation in neurosurgical practice; however rare pathologies such as thrombosed epidural varix may mimic them by causing radicular symptoms. In this case report, we present a 26-year-old man with the complaint of back and right leg pain who was operated for right L4-5 disc herniation. The lesion interpreted as an extruded disc herniation preoperatively was found to be a thrombosed epidural varix compressing the nerve root preoperatively. The nerve root was decompressed by shrinking the lesion with bipolar thermocoagulation and excision. The patient's complaints disappeared in the postoperative period. Thrombosed lumbar epidural varices may mimic lumbar disc herniations both radiologically and clinically. Therefore, must be kept in mind in the differential diagnosis of lumbar disc herniations. Microsurgical techniques are mandatory for the treatment of these pathologies and decompression with thermocoagulation and excision is an efficient method. PMID:27446525

  11. Strongly magnetized accretion discs require poloidal flux

    NASA Astrophysics Data System (ADS)

    Salvesen, Greg; Armitage, Philip J.; Simon, Jacob B.; Begelman, Mitchell C.

    2016-05-01

    Motivated by indirect observational evidence for strongly magnetized accretion discs around black holes, and the novel theoretical properties of such solutions, we investigate how a strong magnetization state can develop and persist. To this end, we perform local simulations of accretion discs with an initially purely toroidal magnetic field of equipartition strength. We demonstrate that discs with zero net vertical magnetic flux and realistic boundary conditions cannot sustain a strong toroidal field. However, a magnetic pressure-dominated disc can form from an initial configuration with a sufficient amount of net vertical flux and realistic boundary conditions. Our results suggest that poloidal flux is a necessary prerequisite for the sustainability of strongly magnetized accretion discs.

  12. Precision manufacturing of compact disc master stampers

    SciTech Connect

    Bifano, T.; Caggiano, H.; Bierden, P.

    1996-12-31

    The authors have developed a new manufacturing process for compact disc master stamper production. Stamper is an industry term for the mold used to replicate polymer CDs in an injection molding device. The stamper surface contains a negative image of the CD`s >1 billion features, each measuring 0.5 {mu}m wide, 1-3{mu}m long, and 150 nm tall. These features are embossed in a spiral pattern on the 138 mm diameter stamper substrate. In conventional mastering, nickel sub-master stampers are generated by electroforming from a glass master with a masked photoresist layer. In the new process, called Precision Stamper Manufacturing (PSM), sub-master stampers are not required - the ceramic master is used directly as a stamper for injection molding. The technology uses precision manufacturing to improve productivity, reduce hazardous waste, and reduce costs in production of master stampers. All critical process steps have been proven feasible in the research reported here. More than 120 minutes of conventional manufacturing processes are replaced by about 20 minutes of precision machining processes, with improved precision in the final component. Another benefit of PSM is that it eliminates most process steps that produce hazardous wastes. Objectives of the experimental research have been to verify feasibility of the method, and to manufacture a prototype CD stamper. Over the past year, we have demonstrated feasibility of all process steps in the new method, and results will be presented. Also, we uncovered and quantified several important limitations for each process step, and combined the individual steps into a manufacturing cycle through which a full-scale working stamper prototype was made. These experiments made use of available facilities at two major equipment suppliers for the CD, an ion machining equipment, and a national research facility, in addition to facilities at Boston University and Prism Corporation.

  13. Structure and evolutionary history of DISC1.

    PubMed

    Sanchez-Pulido, Luis; Ponting, Chris P

    2011-10-15

    Evolutionary and protein structural analyses can provide functional insights into genes implicated in human psychiatric diseases. Even eukaryotic organisms lacking nervous systems contain homologues of many key signalling molecules of animal neurons implying that human cognition derives, in part, from modifications of ancestral molecules and complexes. One protein whose evolutionary origin is obscure is DISC1 (disrupted in schizophrenia 1) whose gene locus has been associated with many psychiatric conditions including schizophrenia, clinical depression and bipolar disorder. This protein's rapid evolution and its unusual amino acid and α-helix composition have hindered searches for DISC1 homologues in species other than vertebrates. Here, we review the evolution and structure of the DISC1 protein in the light of in-depth sequence analyses. These predict DISC1 orthologues in diverse eukaryotic organisms, including early-branching animals such as amphioxus, sea anemone, amoebas and Trichoplax, and in plants and algae. DISC1 thus is widespread among eukaryotes, although it remains absent from fungi, nematodes and Diptera, including fruit flies. These observations now permit studies of DISC1 function in simple non-vertebrate model organisms. Surprisingly, these analyses also identify between two and four sequence repeats in DISC1 orthologues. The first two of these repeats show significant sequence similarity to the UVR family of globular domains. These UVR-like repeats are predicted to contain, not coiled coil structures, but rather two closely associated antiparallel α-helices. One common missense variant in DISC1 (L607F) lies within the second DISC1 UVR-like domain. These observations should assist in delineating the functional regions of the DISC1 protein. PMID:21852244

  14. Clinical Features of Herniated Disc at Cervicothoracic Junction Level Treated by Anterior Approach

    PubMed Central

    Lee, Jun Gue; Kim, Hyeun Sung; Ju, Chang Il

    2016-01-01

    Objective The anterior approach for C7-T1 disc herniation may be challenging because of obstruction by the manubrium and the narrow operative field. This study aimed to investigate the clinical and neurological outcomes of anterior approach for C7-T1 disc herniation. Methods We retrospectively evaluated 13 patients who underwent the anterior approach for C7-T1 disc herniation by a single surgeon within a period of 11 years (2003-2014). The minimum follow-up duration was 6 months. We describe the clinical presentation, radiographic findings, neurological outcome, and related complications. Results Of 372 patients with single-level anterior discectomy and fusion or artificial disc replacement for cervical disc herniation, 13 (3.5%) had C7-T1 disc herniation. The main clinical presentation was unilateral motor weakness in intrinsic hand muscles (11 patients), along with numbness, pain, and tingling sensation that radiate down the arm to the little finger. Most of the patients improved after surgery via the anterior approach. Ten patients underwent successful anterior discectomy and fusion by the standard supramanubrial Smith-Robinson approach, but 2 needed additional manubriotomy and sternotomy. In 1 patient, we performed surgery at a wrong level because the correct level was difficult to identify intraoperatively. Two patients had transient vocal dysfunction, but none had major complications related to injuries of the great vessels such as the thoracic duct or esophagus. Conclusion For patients who require direct anterior decompression for C7-T1 disc herniation, the anterior approach is relatively feasible. However, care should be taken to overcome physical constraints by the manubrium and slope. PMID:27437013

  15. Treatment of the degenerated intervertebral disc; closure, repair and regeneration of the annulus fibrosus.

    PubMed

    Sharifi, Shahriar; Bulstra, Sjoerd K; Grijpma, Dirk W; Kuijer, Roel

    2015-10-01

    Degeneration of the intervertebral disc (IVD) and disc herniation are two causes of low back pain. The aetiology of these disorders is unknown, but tissue weakening, which primarily occurs due to inherited genetic factors, ageing, nutritional compromise and loading history, is the basic factor causing disc degeneration. Symptomatic disc herniation mainly causes radicular pain. Current treatments of intervertebral disc degeneration and low back pain are based on alleviating the symptoms and comprise administration of painkillers or surgical methods such as spinal fusion. None of these methods is completely successful. Current research focuses on regeneration of the IVD and particularly on regeneration of the nucleus pulposus. Less attention has been directed to the repair or regeneration of the annulus fibrosus, although this is the key to successful nucleus pulposus, and therewith IVD, repair. This review focuses on the importance of restoring the function of the annulus fibrosus, as well as on the repair, replacement or regeneration of the annulus fibrosus in combination with restoration of the function of the nucleus pulposus, to treat low back pain. PMID:24616324

  16. Maintenance of imaginal disc plasticity and regenerative potential in Drosophila by p53.

    PubMed

    Wells, Brent S; Johnston, Laura A

    2012-01-15

    Following irradiation (IR), the DNA damage response (DDR) activates p53, which triggers death of cells in which repair cannot be completed. Lost tissue is then replaced and re-patterned through regeneration. We have examined the role of p53 in co-regulation of the DDR and tissue regeneration following IR damage in Drosophila. We find that after IR, p53 is required for imaginal disc cells to repair DNA, and in its absence the damage marker, γ-H2AX is persistently expressed. p53 is also required for the compensatory proliferation and re-patterning of the damaged discs, and our results indicate that cell death is not required to trigger these processes. We identify an IR-induced delay in developmental patterning in wing discs that accompanies an animal-wide delay of the juvenile-adult transition, and demonstrate that both of these delays require p53. In p53 mutants, the lack of developmental delays and of damage resolution leads to anueploidy and tissue defects, and ultimately to morphological abnormalities and adult inviability. We propose that p53 maintains plasticity of imaginal discs by co-regulating the maintenance of genome integrity and disc regeneration, and coordinating these processes with the physiology of the animal. These findings place p53 in a role as master coordinator of DNA and tissue repair following IR. PMID:22036477

  17. Toxicology of chlorofluorocarbon replacements.

    PubMed Central

    Dekant, W

    1996-01-01

    Chlorofluorocarbons (CFCs) are stable in the atmosphere and may reach the stratosphere. They are cleaved by UV-radiation in the stratosphere to yield chlorine radicals, which are thought to interfere with the catalytic cycle of ozone formation and destruction and deplete stratospheric ozone concentrations. Due to potential adverse health effects of ozone depletion, chlorofluorocarbon replacements with much lower or absent ozone depleting potential are developed. The toxicology of these compounds that represent chlorofluorohydrocarbons (HCFCs) or fluorohydrocarbons (HFCs) has been intensively studied. All compounds investigated (1, 1-dichloro-1-fluoroethane [HCFC-141b], 1,1,1,2-tetrafluoroethane [HFC-134a], pentafluoroethane [HFC-125], 1-chloro- 1,2,2,2-tetrafluoroethane [HCFC-124], and 1,1-dichloro-2,2,2-trifluoroethane [HCFC-123]) show only a low potential for skin and eye irritation. Chronic adverse effects on the liver (HCFC-123) and the testes (HCFC-141b and HCFC-134a), including tumor formation, were observed in long-term inhalation studies in rodents using very high concentrations of these CFC replacements. All CFC replacements are, to varying extents, biotransformed in the organism, mainly by cytochrome P450-catalyzed oxidation of C-H bonds. The formed acyl halides are hydrolyzed to give excretable carboxylic acids; halogenated aldehydes that are formed may be further oxidized to halogenated carboxylic acids or reduced to halogenated alcohols, which are excretory metabolites in urine from rodents exposed experimentally to CFC replacements. The chronic toxicity of the CFC replacements studied is unlikely to be of relevance for humans exposed during production and application of CFC replacements. PMID:8722112

  18. Spontaneous Regression of Herniated Lumbar Disc with New Disc Protrusion in the Adjacent Level.

    PubMed

    Hakan, Tayfun; Gürcan, Serkan

    2016-01-01

    Spontaneous regression of herniated lumbar discs was reported occasionally. The mechanisms proposed for regression of disc herniation are still incomplete. This paper describes and discusses a case of spontaneous regression of herniated lumbar discs with a new disc protrusion in the adjacent level. A 41-year-old man was admitted with radiating pain and numbness in the left lower extremity with a left posterolateral disc extrusion at L5-S1 level. He was admitted to hospital with low back pain due to disc herniation caudally immigrating at L4-5 level three years ago. He refused the surgical intervention that was offered and was treated conservatively at that time. He had no neurological deficit and a history of spontaneous regression of the extruded lumbar disc; so, a conservative therapy, including bed rest, physical therapy, nonsteroidal anti-inflammatory drugs, and analgesics, was advised. In conclusion, herniated lumbar disc fragments may regress spontaneously. Reports are prone to advise conservative treatment for extruded or sequestrated lumbar disc herniations. However, these patients should be followed up closely; new herniation at adjacent/different level may occur. Furthermore, it is important to know which herniated disk should be removed and which should be treated conservatively, because disc herniation may cause serious complications as muscle weakness and cauda equine syndrome. PMID:27429818

  19. Spontaneous Regression of Herniated Lumbar Disc with New Disc Protrusion in the Adjacent Level

    PubMed Central

    Gürcan, Serkan

    2016-01-01

    Spontaneous regression of herniated lumbar discs was reported occasionally. The mechanisms proposed for regression of disc herniation are still incomplete. This paper describes and discusses a case of spontaneous regression of herniated lumbar discs with a new disc protrusion in the adjacent level. A 41-year-old man was admitted with radiating pain and numbness in the left lower extremity with a left posterolateral disc extrusion at L5-S1 level. He was admitted to hospital with low back pain due to disc herniation caudally immigrating at L4-5 level three years ago. He refused the surgical intervention that was offered and was treated conservatively at that time. He had no neurological deficit and a history of spontaneous regression of the extruded lumbar disc; so, a conservative therapy, including bed rest, physical therapy, nonsteroidal anti-inflammatory drugs, and analgesics, was advised. In conclusion, herniated lumbar disc fragments may regress spontaneously. Reports are prone to advise conservative treatment for extruded or sequestrated lumbar disc herniations. However, these patients should be followed up closely; new herniation at adjacent/different level may occur. Furthermore, it is important to know which herniated disk should be removed and which should be treated conservatively, because disc herniation may cause serious complications as muscle weakness and cauda equine syndrome. PMID:27429818

  20. Stem cells sources for intervertebral disc regeneration

    PubMed Central

    Vadalà, Gianluca; Russo, Fabrizio; Ambrosio, Luca; Loppini, Mattia; Denaro, Vincenzo

    2016-01-01

    Intervertebral disc regeneration field is rapidly growing since disc disorders represent a major health problem in industrialized countries with very few possible treatments. Indeed, current available therapies are symptomatic, and surgical procedures consist in disc removal and spinal fusion, which is not immune to regardable concerns about possible comorbidities, cost-effectiveness, secondary risks and long-lasting outcomes. This review paper aims to share recent advances in stem cell therapy for the treatment of intervertebral disc degeneration. In literature the potential use of different adult stem cells for intervertebral disc regeneration has already been reported. Bone marrow mesenchymal stromal/stem cells, adipose tissue derived stem cells, synovial stem cells, muscle-derived stem cells, olfactory neural stem cells, induced pluripotent stem cells, hematopoietic stem cells, disc stem cells, and embryonic stem cells have been studied for this purpose either in vitro or in vivo. Moreover, several engineered carriers (e.g., hydrogels), characterized by full biocompatibility and prompt biodegradation, have been designed and combined with different stem cell types in order to optimize the local and controlled delivery of cellular substrates in situ. The paper overviews the literature discussing the current status of our knowledge of the different stem cells types used as a cell-based therapy for disc regeneration. PMID:27247704

  1. Stem cells sources for intervertebral disc regeneration.

    PubMed

    Vadalà, Gianluca; Russo, Fabrizio; Ambrosio, Luca; Loppini, Mattia; Denaro, Vincenzo

    2016-05-26

    Intervertebral disc regeneration field is rapidly growing since disc disorders represent a major health problem in industrialized countries with very few possible treatments. Indeed, current available therapies are symptomatic, and surgical procedures consist in disc removal and spinal fusion, which is not immune to regardable concerns about possible comorbidities, cost-effectiveness, secondary risks and long-lasting outcomes. This review paper aims to share recent advances in stem cell therapy for the treatment of intervertebral disc degeneration. In literature the potential use of different adult stem cells for intervertebral disc regeneration has already been reported. Bone marrow mesenchymal stromal/stem cells, adipose tissue derived stem cells, synovial stem cells, muscle-derived stem cells, olfactory neural stem cells, induced pluripotent stem cells, hematopoietic stem cells, disc stem cells, and embryonic stem cells have been studied for this purpose either in vitro or in vivo. Moreover, several engineered carriers (e.g., hydrogels), characterized by full biocompatibility and prompt biodegradation, have been designed and combined with different stem cell types in order to optimize the local and controlled delivery of cellular substrates in situ. The paper overviews the literature discussing the current status of our knowledge of the different stem cells types used as a cell-based therapy for disc regeneration. PMID:27247704

  2. Shear Mechanics of the TMJ Disc

    PubMed Central

    Juran, C.M.; Dolwick, M.F.; McFetridge, P.S.

    2012-01-01

    The temporomandibular joint (TMJ) is a complex hinge and gliding joint that induces significant shear loads onto the fibrocartilage TMJ disc during jaw motion. The purpose of this study was to assess regional variation in the disc’s shear loading characteristics under physiologically relevant loads and to associate those mechanical findings with common clinical observations of disc fatigue and damage. Porcine TMJ discs were compressed between an axially translating bottom platen and a 2.5-cm-diameter indenter within a hydrated testing chamber. Discs were cyclically sheared at 0.5, 1, or 5 Hz to 1, 3, or 5% shear strain. Within the anterior and intermediate regions of the disc when sheared in the anteroposterior direction, both shear and compressive moduli experienced a significant decrease from instantaneous to steady state, while the posterior region’s compressive modulus decreased approximately 5%, and no significant loss of shear modulus was noted. All regions retained their shear modulus within 0.5% of instantaneous values when shear was applied in the mediolateral direction. The results of the disc’s regional shear mechanics suggest an observable and predictable link with the common clinical observation that the posterior region of the disc is most often the zone in which fatigue occurs, which may lead to disc damage and perforation. PMID:23166043

  3. Neocartilage integration in temporomandibular joint discs: physical and enzymatic methods

    PubMed Central

    Murphy, Meghan K.; Arzi, Boaz; Prouty, Shannon M.; Hu, Jerry C.; Athanasiou, Kyriacos A.

    2015-01-01

    Integration of engineered musculoskeletal tissues with adjacent native tissues presents a significant challenge to the field. Specifically, the avascularity and low cellularity of cartilage elicit the need for additional efforts in improving integration of neocartilage within native cartilage. Self-assembled neocartilage holds significant potential in replacing degenerated cartilage, though its stabilization and integration in native cartilage require further efforts. Physical and enzymatic stabilization methods were investigated in an in vitro model for temporomandibular joint (TMJ) disc degeneration. First, in phase 1, suture, glue and press-fit constructs were compared in TMJ disc intermediate zone defects. In phase 1, suturing enhanced interfacial shear stiffness and strength immediately; after four weeks, a 15-fold increase in stiffness and a ninefold increase in strength persisted over press-fit. Neither suture nor glue significantly altered neocartilage properties. In phase 2, the effects of the enzymatic stabilization regimen composed of lysyl oxidase, CuSO4 and hydroxylysine were investigated. A full factorial design was employed, carrying forward the best physical method from phase 1, suturing. Enzymatic stabilization significantly increased interfacial shear stiffness after eight weeks. Combined enzymatic stabilization and suturing led to a fourfold increase in shear stiffness and threefold increase in strength over press-fit. Histological analysis confirmed the presence of a collagen-rich interface. Enzymatic treatment additionally enhanced neocartilage mechanical properties, yielding a tensile modulus over 6 MPa and compressive instantaneous modulus over 1200 kPa at eight weeks. Suturing enhances stabilization of neocartilage, and enzymatic treatment enhances functional properties and integration of neocartilage in the TMJ disc. Methods developed here are applicable to other orthopaedic soft tissues, including knee meniscus and hyaline articular

  4. Mastering methodological pitfalls for surviving the metagenomic jungle.

    PubMed

    Delmont, Tom O; Simonet, Pascal; Vogel, Timothy M

    2013-08-01

    Metagenomics is a culture- and PCR-independent approach that is now widely exploited for directly studying microbial evolution, microbial ecology, and developing biotechnologies. Observations and discoveries are critically dependent on DNA extraction methods, sequencing technologies, and bioinformatics tools. The potential pitfalls need to be understood and, to some degree, mastered if the resulting data are to survive scrutiny. In particular, methodological variations appear to affect results from different ecosystems differently, thus increasing the risk of biological and ecological misinterpretation. Part of the difficulty is derived from the lack of knowledge concerning the true microbial diversity and because no approach can guarantee accessing microorganisms in the same proportion in which they exist in the environment. However, the variation between different approaches (e.g. DNA extraction techniques, sequence annotation systems) can be used to evaluate whether observations are meaningful. These methodological variations can be integrated into the error analysis before comparing microbial communities. PMID:23757040

  5. Individual therapy for couple problems: perspectives and pitfalls.

    PubMed

    Gurman, Alan S; Burton, Mark

    2014-10-01

    Despite the demonstrated efficacy of conjoint couple therapy, many clients seeking help for couple problems ultimately find themselves in individual therapy for these concerns. Individual therapy for couple problems (ITCP) may evolve from a partner's refusal of conjoint therapy or from the treatment format preferences of either the client or therapist. Having acknowledged the role of partner refusals, we offer some perspectives about the idiosyncratic personal factors and professional background factors that may lead therapists to provide ITCP and discuss the significant pitfalls in its practice. We emphasize five central areas of concern in the ongoing practice of ITCP: structural constraints on change; therapist side-taking and the therapeutic alliance; inaccurate assessments based on individual client reports; therapeutic focus; and ethical issues relevant to both attending and nonattending partners. We conclude by urging that this very important but largely neglected topic be paid greater attention in psychotherapy research, training and continuing education. PMID:24773422

  6. [Cardiology online: impact and pitfalls of Internet medical news].

    PubMed

    Wood, Shelley M; Topol, Eric J

    2012-01-01

    Twenty years ago, the main sources for physicians seeking information on new procedures, drugs, or devices were meetings and medical journals. The dawn of the Internet radically transformed how news and information is delivered and absorbed, beginning with the launch of online journals back in the mid-1990s. A decade and a half later, physicians can learn about new innovations the moment they are made public, and they can get that news from their phones and tablets, their Twitter or Facebook accounts, or via their favorite blog or medical news web site. Along with the clear advantages of accessing new medical information any time of day comes the need for physicians to be aware of the pitfalls of online medical content and to have a heightened sense of responsibility when it comes to integrating information gleaned online into their medical practices. PMID:22322467

  7. The Head-fixed Behaving Rat—Procedures and Pitfalls

    PubMed Central

    Schwarz, Cornelius; Hentschke, Harald; Butovas, Sergejus; Haiss, Florent; Stüttgen, Maik C; Gerdjikov, Todor V; Bergner, Caroline G; Waiblinger, Christian

    2010-01-01

    This paper describes experimental techniques with head-fixed, operantly conditioned rodents that allow the control of stimulus presentation and tracking of motor output at hitherto unprecedented levels of spatio-temporal precision. Experimental procedures for the surgery and behavioral training are presented. We place particular emphasis on potential pitfalls using these procedures in order to assist investigators who intend to engage in this type of experiment. We argue that head-fixed rodent models, by allowing the combination of methodologies from molecular manipulations, intracellular electrophysiology, and imaging to behavioral measurements, will be instrumental in combining insights into the functional neuronal organization at different levels of observation. Provided viable behavioral methods are implemented, model systems based on rodents will be complementary to current primate models—the latter providing highest comparability with the human brain, while the former offer hugely advanced methodologies on the lower levels of organization, for example, genetic alterations, intracellular electrophysiology, and imaging. PMID:20954892

  8. Chemometrics applied to vibrational spectroscopy: overview, challenges and pitfalls

    SciTech Connect

    Haaland, D.M.

    1996-10-01

    Chemometric multivariate calibration methods are rapidly impacting quantitative infrared spectroscopy in many positive ways. The combination of vibrational spectroscopy and chemometrics has been used by industry for quality control and process monitoring. The growth of these methods has been phenomenal in the past decade. Yet, as with any new technology, there are growing pains. The methods are so powerful at finding correlations in the data, that when used without great care they can readily yield results that are not valid for the analysis of future unknown samples. In this paper, the power of the multivariate calibration methods is discussed while pointing out common pitfalls and some remaining challenges that may slow the implementation of chemometrics in research and industry.

  9. Surgery for Locally Recurrent Rectal Cancer: Tips, Tricks, and Pitfalls.

    PubMed

    Warrier, Satish K; Heriot, Alexander G; Lynch, Andrew Craig

    2016-06-01

    Rectal cancer can recur locally in up to 10% of the patients who undergo definitive resection for their primary cancer. Surgical salvage is considered appropriate in the curative setting as well as select cases with palliative intent. Disease-free survival following salvage resection is dependent upon achieving an R0 resection margin. A clear understanding of applied surgical anatomy, appropriate preoperative planning, and a multidisciplinary approach to aggressive soft tissue, bony, and vascular resection with appropriate reconstruction is necessary. Technical tips, tricks, and pitfalls that may assist in managing these cancers are discussed and the roles of additional boost radiation and intraoperative radiation therapy in the management of such cancers are also discussed. PMID:27247536

  10. Disseminated adenovirus infection in an immunocompromised host. Pitfalls in diagnosis.

    PubMed

    Landry, M L; Fong, C K; Neddermann, K; Solomon, L; Hsiung, G D

    1987-09-01

    In this report, a bone marrow transplant recipient with rapidly fatal gastroenteritis is presented. The presence of intranuclear inclusions on postmortem light microscopic examination of liver, lung, and small bowel tissue was considered diagnostic of cytomegalovirus infection. However, electron microscopic examination of liver tissue demonstrated adenovirus infection. This was confirmed by isolation of an adenovirus type 2 with unusual laboratory features from liver, lung, colon contents, serum, esophageal swab, and oral ulcerations. Results of a complement fixation test for antibodies to adenovirus performed on postmortem serum samples were negative, and a titer of 1:4 was noted for antibody against cytomegalovirus. This case illustrates the diagnostic pitfalls that may be encountered in establishing a specific viral diagnosis in severely ill patients. PMID:2821806

  11. The neuroaesthetics of prose fiction: pitfalls, parameters and prospects.

    PubMed

    Burke, Michael

    2015-01-01

    There is a paucity of neuroaesthetic studies on prose fiction. This is in contrast to the very many impressive studies that have been conducted in recent times on the neuroaesthetics of sister arts such as painting, music and dance. Why might this be the case, what are its causes and, of greatest importance, how can it best be resolved? In this article, the pitfalls, parameters and prospects of a neuroaesthetics of prose fiction will be explored. The article itself is part critical review, part methodological proposal and part opinion paper. Its aim is simple: to stimulate, excite and energize thinking in the discipline as to how prose fiction might be fully integrated in the canon of neuroaesthetics and to point to opportunities where neuroimaging studies on literary discourse processing might be conducted in collaborative work bringing humanists and scientists together. PMID:26283953

  12. Potential pitfalls of strain rate imaging: angle dependency

    NASA Technical Reports Server (NTRS)

    Castro, P. L.; Greenberg, N. L.; Drinko, J.; Garcia, M. J.; Thomas, J. D.

    2000-01-01

    Strain Rate Imaging (SRI) is a new echocardiographic technique that allows for the real-time determination of myocardial SR, which may be used for the early and accurate detection of coronary artery disease. We sought to study whether SR is affected by scan line alignment in a computer simulation and an in vivo experiment. Through the computer simulation and the in vivo experiment we generated and validated safe scanning sectors within the ultrasound scan sector and showed that while SRI will be an extremely valuable tool in detecting coronary artery disease there are potential pitfalls for the unwary clinician. Only after accounting for these affects due to angle dependency, can clinicians utilize SRI's potential as a valuable tool in detecting coronary artery disease.

  13. The neuroaesthetics of prose fiction: pitfalls, parameters and prospects

    PubMed Central

    Burke, Michael

    2015-01-01

    There is a paucity of neuroaesthetic studies on prose fiction. This is in contrast to the very many impressive studies that have been conducted in recent times on the neuroaesthetics of sister arts such as painting, music and dance. Why might this be the case, what are its causes and, of greatest importance, how can it best be resolved? In this article, the pitfalls, parameters and prospects of a neuroaesthetics of prose fiction will be explored. The article itself is part critical review, part methodological proposal and part opinion paper. Its aim is simple: to stimulate, excite and energize thinking in the discipline as to how prose fiction might be fully integrated in the canon of neuroaesthetics and to point to opportunities where neuroimaging studies on literary discourse processing might be conducted in collaborative work bringing humanists and scientists together. PMID:26283953

  14. Merits and Pitfalls of Currently Used Diagnostic Tools in Mycetoma

    PubMed Central

    van de Sande, Wendy W. J.; Fahal, Ahmed H.; Goodfellow, Michael; Mahgoub, El Sheikh; Welsh, Oliverio; Zijlstra, Ed E.

    2014-01-01

    Treatment of mycetoma depends on the causative organism and since many organisms, both actinomycetes (actinomycetoma) and fungi (eumycetoma), are capable of producing mycetoma, an accurate diagnosis is crucial. Currently, multiple diagnostic tools are used to determine the extent of infections and to identify the causative agents of mycetoma. These include various imaging, cytological, histopathological, serological, and culture techniques; phenotypic characterisation; and molecular diagnostics. In this review, we summarize these techniques and identify their merits and pitfalls in the identification of the causative agents of mycetoma and the extent of the disease. We also emphasize the fact that there is no ideal diagnostic tool available to identify the causative agents and that future research should focus on the development of new and reliable diagnostic tools. PMID:24992636

  15. Multi-criteria decision analysis: Limitations, pitfalls, and practical difficulties

    SciTech Connect

    Kujawski, Edouard

    2003-02-01

    The 2002 Winter Olympics women's figure skating competition is used as a case study to illustrate some of the limitations, pitfalls, and practical difficulties of Multi-Criteria Decision Analysis (MCDA). The paper compares several widely used models for synthesizing the multiple attributes into a single aggregate value. The various MCDA models can provide conflicting rankings of the alternatives for a common set of information even under states of certainty. Analysts involved in MCDA need to deal with the following challenging tasks: (1) selecting an appropriate analysis method, and (2) properly interpreting the results. An additional trap is the availability of software tools that implement specific MCDA models that can beguile the user with quantitative scores. These conclusions are independent of the decision domain and they should help foster better MCDA practices in many fields including systems engineering trade studies.

  16. Scrum and Global Delivery: Pitfalls and Lessons Learned

    NASA Astrophysics Data System (ADS)

    Sadun, Cristiano

    Two trends are becoming widespread in software development work—agile development processes and global delivery, both promising sizable benefits in productivity, capacity and so on. Combining the two is a highly attractive possibility, even more so in fast-paced and constrained commercial software engineering projects. However, a degree of conflict exists between the assumptions underlying the two ideas, leading to pitfalls and challenges in agile/distributed projects which are new, both with respect to traditional development and agile or distributed efforts adopted separately. Succeeding in commercial agile/distributed projects implies recognizing these new challenges, proactively planning for them, and actively put in place solutions and methods to overcome them. This chapter illustrates some of the typical challenges that were met during real-world commercial projects, and how they were solved.

  17. Extrapolation technique pitfalls in asymmetry measurements at colliders

    NASA Astrophysics Data System (ADS)

    Colletti, Katrina; Hong, Ziqing; Toback, David; Wilson, Jonathan S.

    2016-09-01

    Asymmetry measurements are common in collider experiments and can sensitively probe particle properties. Typically, data can only be measured in a finite region covered by the detector, so an extrapolation from the visible asymmetry to the inclusive asymmetry is necessary. Often a constant multiplicative factor is advantageous for the extrapolation and this factor can be readily determined using simulation methods. However, there is a potential, avoidable pitfall involved in the determination of this factor when the asymmetry in the simulated data sample is small. We find that to obtain a reliable estimate of the extrapolation factor, the number of simulated events required rises as the inverse square of the simulated asymmetry; this can mean that an unexpectedly large sample size is required when determining the extrapolation factor.

  18. Avoiding the pitfalls of adaptive management implementation in Swedish silviculture.

    PubMed

    Rist, Lucy; Felton, Adam; Mårald, Erland; Samuelsson, Lars; Lundmark, Tomas; Rosvall, Ola

    2016-02-01

    There is a growing demand for alternatives to Sweden's current dominant silvicultural system, driven by a desire to raise biomass production, meet environmental goals and mitigate climate change. However, moving towards diversified forest management that deviates from well established silvicultural practices carries many uncertainties and risks. Adaptive management is often suggested as an effective means of managing in the context of such complexities. Yet there has been scepticism over its appropriateness in cases characterised by large spatial extents, extended temporal scales and complex land ownership-characteristics typical of Swedish forestry. Drawing on published research, including a new paradigm for adaptive management, we indicate how common pitfalls can be avoided during implementation. We indicate the investment, infrastructure, and considerations necessary to benefit from adaptive management. In doing so, we show how this approach could offer a pragmatic operational model for managing the uncertainties, risks and obstacles associated with new silvicultural systems and the challenges facing Swedish forestry. PMID:26744049

  19. Clinical and Biochemical Pitfalls in the Diagnosis of Peroxisomal Disorders.

    PubMed

    Klouwer, Femke C C; Huffnagel, Irene C; Ferdinandusse, Sacha; Waterham, Hans R; Wanders, Ronald J A; Engelen, Marc; Poll-The, Bwee Tien

    2016-08-01

    Peroxisomal disorders are a heterogeneous group of genetic metabolic disorders, caused by a defect in peroxisome biogenesis or a deficiency of a single peroxisomal enzyme. The peroxisomal disorders include the Zellweger spectrum disorders, the rhizomelic chondrodysplasia punctata spectrum disorders, X-linked adrenoleukodystrophy, and multiple single enzyme deficiencies. There are several core phenotypes caused by peroxisomal dysfunction that clinicians can recognize. The diagnosis is suggested by biochemical testing in blood and urine and confirmed by functional assays in cultured skin fibroblasts, followed by mutation analysis. This review describes the phenotype of the main peroxisomal disorders and possible pitfalls in (laboratory) diagnosis to aid clinicians in the recognition of this group of diseases. PMID:27089543

  20. Hyperpolarized Renal Magnetic Resonance Imaging: Potential and Pitfalls.

    PubMed

    Laustsen, Christoffer

    2016-01-01

    The introduction of dissolution dynamic nuclear polarization (d-DNP) technology has enabled a new paradigm for renal imaging investigations. It allows standard magnetic resonance imaging complementary renal metabolic and functional fingerprints within seconds without the use of ionizing radiation. Increasing evidence supports its utility in preclinical research in which the real-time interrogation of metabolic turnover can aid the physiological and pathophysiological metabolic and functional effects in ex vivo and in vivo models. The method has already been translated to humans, although the clinical value of this technology is unknown. In this paper, I review the potential benefits and pitfalls associated with dissolution dynamic nuclear polarization in preclinical research and its translation to renal patients. PMID:26973539

  1. Hyperpolarized Renal Magnetic Resonance Imaging: Potential and Pitfalls

    PubMed Central

    Laustsen, Christoffer

    2016-01-01

    The introduction of dissolution dynamic nuclear polarization (d-DNP) technology has enabled a new paradigm for renal imaging investigations. It allows standard magnetic resonance imaging complementary renal metabolic and functional fingerprints within seconds without the use of ionizing radiation. Increasing evidence supports its utility in preclinical research in which the real-time interrogation of metabolic turnover can aid the physiological and pathophysiological metabolic and functional effects in ex vivo and in vivo models. The method has already been translated to humans, although the clinical value of this technology is unknown. In this paper, I review the potential benefits and pitfalls associated with dissolution dynamic nuclear polarization in preclinical research and its translation to renal patients. PMID:26973539

  2. Electron beam recording of optical disc

    NASA Astrophysics Data System (ADS)

    Cartwright, Giles; Reynolds, Gerald; Baylis, Chris; Pearce, Adrian; Dix, Colin; Ogilvie, Nick

    2002-09-01

    The Nimbus Technology & Engineering e -Beam Mastering System was developed to gain a large improvement in optical disc and structured hard disc recording capacity, significantly more than is possible from deep UV and SIL mastering. The current electron beam recorder is essentially a production machine capable of making full-length exposures at capacities of up to 50 GB with a simple low-cost upgrade path to disc capacities of several hundred gigabytes and beyond and hard disk drives (HDD) with capacities of up to 1 tera bit per square inch.

  3. [Lumbar disc herniation and andrological diseases].

    PubMed

    Jin, Bao-fang

    2015-10-01

    Lumbar disc herniation is a common male disease. In the past, More academic attention was directed to its relationship with lumbago and leg pain than to its association with andrological diseases. Studies show that central lumber intervertebral disc herniation may cause cauda equina injury and result in premature ejaculation, erectile dysfunction, chronic pelvic pain syndrome, priapism, and emission. This article presents an overview on the correlation between central lumbar intervertebral disc herniation and andrological diseases, focusing on the aspects of etiology, pathology, and clinical progress, hoping to invite more attention from andrological and osteological clinicians. PMID:26665671

  4. Spectroscopic Parameters of Lumbar Intervertebral Disc Material

    NASA Astrophysics Data System (ADS)

    Terbetas, G.; Kozlovskaja, A.; Varanius, D.; Graziene, V.; Vaitkus, J.; Vaitkuviene, A.

    2009-06-01

    There are numerous methods of investigating intervertebral disc. Visualization methods are widely used in clinical practice. Histological, imunohistochemical and biochemical methods are more used in scientific research. We propose that a new spectroscopic investigation would be useful in determining intervertebral disc material, especially when no histological specimens are available. Purpose: to determine spectroscopic parameters of intervertebral disc material; to determine emission spectra common for all intervertebral discs; to create a background for further spectroscopic investigation where no histological specimen will be available. Material and Methods: 20 patients, 68 frozen sections of 20 μm thickness from operatively removed intervertebral disc hernia were excited by Nd:YAG microlaser STA-01-TH third harmonic 355 nm light throw 0, 1 mm fiber. Spectrophotometer OceanOptics USB2000 was used for spectra collection. Mathematical analysis of spectra was performed by ORIGIN multiple Gaussian peaks analysis. Results: In each specimen of disc hernia were found distinct maximal spectral peaks of 4 types supporting the histological evaluation of mixture content of the hernia. Fluorescence in the spectral regions 370-700 nm was detected in the disc hernias. The main spectral component was at 494 nm and the contribution of the components with the peak wavelength values at 388 nm, 412 nm and 435±5 nm were varying in the different groups of samples. In comparison to average spectrum of all cases, there are 4 groups of different spectral signatures in the region 400-500 nm in the patient groups, supporting a clinical data on different clinical features of the patients. Discussion and Conclusion: besides the classical open discectomy, new minimally invasive techniques of treating intervertebral disc emerge (PLDD). Intervertebral disc in these techniques is assessed by needle, no histological specimen is taken. Spectroscopic investigation via fiber optics through the

  5. Python import replacement

    Energy Science and Technology Software Center (ESTSC)

    2011-10-01

    SmartImport.py is a Python source-code file that implements a replacement for the standard Python module importer. The code is derived from knee.py, a file in the standard Python diestribution , and adds functionality to improve the performance of Python module imports in massively parallel contexts.

  6. Replacing America's Job Bank

    ERIC Educational Resources Information Center

    Vollman, Jim

    2009-01-01

    The Job Central National Labor Exchange (www.jobcentral.com) has become the effective replacement for America's Job Bank with state workforce agencies and, increasingly, with community colleges throughout the country. The American Association of Community Colleges (AACC) has formed a partnership with Job Central to promote its use throughout the…

  7. Clinical pitfalls in diagnosis of nonmuscle-invasive bladder cancer.

    PubMed

    Serretta, Vincenzo; Scalici Gesolfo, Cristina

    2015-10-01

    Current global economic crisis imposes healthcare system to reduce unnecessary investigations and increase early detection of tumors, to decrease the costs of an advanced disease. Several diagnostic pitfalls may occur dealing with bladder cancer (BC), particularly in nonmuscle-invasive (NMIBC) one. Hematuria, the commonest sign in NMIBC, is often underestimated. Urinary cytology is highly specific for high-grade tumors, but has a low sensitivity for low-grade BC, is operator dependent, and not always obtainable in clinical practice. Numerous urinary tests are available to ameliorate the accuracy of cytology, but none of them is routinly used in urological practice. Ultrasound could hardly detect a small bladder tumor, especially if located in the bladder neck or in the anterior wall. Computed tomography (CT) is widely adopted as an alternative to conventional urography, but its usefulness in patients with hematuria is still debated. MRI has a higher accuracy than CT for staging BC and evaluate the bladder-wall invasion. A negative cystoscopy cannot exclude Tis and should be accompanied by urinary cytology in patients with suspected Tis or high-risk NMIBC; however, new techniques such as narrow band imaging (NBI) and photodynamic (PDD) increase the detection rate of BC and flat lesions. Nearly half of all diagnostic resections present omission of muscle in the specimen or its mention in the pathology report, which is associated with an increased mortality. An adequate muscle sampling during endoscopic resection is mandatory, particularly in patients with high-grade disease. Recognition of pitfalls in diagnosis and management of BC represents the first step for a correct approach. PMID:26481718

  8. [Revision surgery after implantation of a vertebral disc prosthesis].

    PubMed

    Hopf, C

    2008-04-01

    Assessment of the revisability of surgery after the endoprosthetic replacement of vertebral discs shows that the surgical approach depends on the time of revision surgery and the reason why it is carried out. Our experience is based on nine revision operations out of 152 cervical vertebra prostheses of the Bryan and Prodisc C types implanted from 2003 to 2007 and 312 endoprostheses of the Charité and Prodisc types implanted from 1999 to 2007. Our own results show differing approaches in perioperative or late postoperative revision operations. Operations to exchange implants were not possible, whereas a change of surgical procedure is the rule. The same access route can usually be selected in the cervical spine, but in the lumbar spine this can only be done perioperatively; if revision surgery is carried out at a later date, an alternative access route must be used. Using strict indications for the primary implant is the only way to prevent postoperative revision surgery that is due to an inaccurate primary assessment and not to the vertebral endoprosthesis (e.g. post-discotomy syndrome, facet joint arthropathy, rotation instability, vertebral slip). The next generation of vertebral disc endoprostheses must incorporate reduced load of the zygapophyseal joints and improved revisability. PMID:18340432

  9. Optical Disc Utilized As A Data Storage System For Reconnaissance

    NASA Astrophysics Data System (ADS)

    Herzog, Donald G.

    1984-01-01

    Electra-optic and Radar sensing reconnaissance systems have many advantages including remote transmission and image data processing that conventional film camera systems do not have. However, data storage and retrieval that was naturally and easily accomplished with film must now be accommodated by other techniques. The optical disc data storage and retrieval systems offer significant advantage towards fulfilling this need. This paper will provide an overview description of the technology, some of the fundamental alternatives of configuration approach, and some examples of where it may be considered in the reconnaissance system. Silver halide film has been and still is the work horse of the image based reconnaissance field. It will not be replaced in the near future either, but rather a gradual transition to total electronic systems is expected. It is not the intent of this paper to debase film, because in fact it has its advantages. We have learned to optimize its advantages and minimize its disadvantages. However optical disc systems have a definite role to play in the reconnaissance field.

  10. Heterotopic Ossification Causing Radiculopathy after Lumbar Total Disc Arthroplasty.

    PubMed

    Jackson, Keith L; Hire, Justin M; Jacobs, Jeremy M; Key, Charles C; DeVine, John G

    2015-06-01

    To date, no reports have presented radiculopathy secondary to heterotopic ossification following lumbar total disc arthroplasty. The authors present a previously unpublished complication of lumbar total disk arthroplasty (TDA) secondary to heterotopic ossification (HO) in the spinal canal, and they propose a modification to the McAfee classification of HO. The patient had undergone an L5/S1 lumbar TDA two years prior due to discogenic back pain. His preoperative back pain was significantly relieved, but he developed new, atraumatic onset radiculopathy. Radiographs and a computed tomography myelogram revealed an implant malposition posteriorly with heterotopic bone formation in the canal, causing an impingement of the traversing nerve root. Revision surgery was performed with implant extraction, L5/S1 anterior lumbar interbody fusion, supplemental posterior decompression, and pedicle screw fixation. The patient tolerated the procedure well, with complete resolution of the radicular leg pain. At a two-year follow up, the patient had a solid fusion without subsidence or recurrence of heterotopic bone. This case represents a novel pattern of heterotopic ossification, and it describes a previously unreported cause for implant failure in lumbar disc replacement surgery-reinforcing the importance of proper intraoperative component positioning. We propose a modification to the existing McAfee classification of HO after TDA with the addition of Class V and VI HO. PMID:26097664

  11. Heterotopic Ossification Causing Radiculopathy after Lumbar Total Disc Arthroplasty

    PubMed Central

    Jackson, Keith L.; Jacobs, Jeremy M.; Key, Charles C.; DeVine, John G.

    2015-01-01

    To date, no reports have presented radiculopathy secondary to heterotopic ossification following lumbar total disc arthroplasty. The authors present a previously unpublished complication of lumbar total disk arthroplasty (TDA) secondary to heterotopic ossification (HO) in the spinal canal, and they propose a modification to the McAfee classification of HO. The patient had undergone an L5/S1 lumbar TDA two years prior due to discogenic back pain. His preoperative back pain was significantly relieved, but he developed new, atraumatic onset radiculopathy. Radiographs and a computed tomography myelogram revealed an implant malposition posteriorly with heterotopic bone formation in the canal, causing an impingement of the traversing nerve root. Revision surgery was performed with implant extraction, L5/S1 anterior lumbar interbody fusion, supplemental posterior decompression, and pedicle screw fixation. The patient tolerated the procedure well, with complete resolution of the radicular leg pain. At a two-year follow up, the patient had a solid fusion without subsidence or recurrence of heterotopic bone. This case represents a novel pattern of heterotopic ossification, and it describes a previously unreported cause for implant failure in lumbar disc replacement surgery-reinforcing the importance of proper intraoperative component positioning. We propose a modification to the existing McAfee classification of HO after TDA with the addition of Class V and VI HO. PMID:26097664

  12. Failed back surgery syndrome: problems, pitfalls and prevention.

    PubMed

    Yaksich, I

    1993-05-01

    Several basic and fundamental principles remain prime considerations in lumbar spine surgery, so a review of these is appropriate in view of the current headlong rush into the use of new and developing technology for lumbar spine surgery. Eighteen hundred and sixty-one laminectomy procedures are reviewed, the majority of these for simple lumbar disc protrusion and spinal canal stenosis but also 204 cases where patients required a surgical procedure for failed back surgery syndrome. Surgical technique and technology will fail when an inappropriate patient is selected for surgical intervention; failure also occurs particularly in lumbar disc protrusion if lateral recess stenosis is undiagnosed and untreated at the time of surgery. The patient's motivation status also has a significant effect on surgical outcome and the optimum patient to submit to surgery for failed back surgery syndrome has sciatica, more severe than backache, a recurrent or residual disc protrusion associated with the stenosis and excellent motivation which is not affected by workers' compensation or other insurance claims or benefit. PMID:8215191

  13. Pitfalls in Persuasion: How Do Users Experience Persuasive Techniques in a Web Service?

    NASA Astrophysics Data System (ADS)

    Segerståhl, Katarina; Kotro, Tanja; Väänänen-Vainio-Mattila, Kaisa

    Persuasive technologies are designed by utilizing a variety of interactive techniques that are believed to promote target behaviors. This paper describes a field study in which the aim was to discover possible pitfalls of persuasion, i.e., situations in which persuasive techniques do not function as expected. The study investigated persuasive functionality of a web service targeting weight loss. A qualitative online questionnaire was distributed through the web service and a total of 291 responses were extracted for interpretative analysis. The Persuasive Systems Design model (PSD) was used for supporting systematic analysis of persuasive functionality. Pitfalls were identified through situations that evoked negative user experiences. The primary pitfalls discovered were associated with manual logging of eating and exercise behaviors, appropriateness of suggestions and source credibility issues related to social facilitation. These pitfalls, when recognized, can be addressed in design by applying functional and facilitative persuasive techniques in meaningful combinations.

  14. Archival-grade optical disc design and international standards

    NASA Astrophysics Data System (ADS)

    Fujii, Toru; Kojyo, Shinichi; Endo, Akihisa; Kodaira, Takuo; Mori, Fumi; Shimizu, Atsuo

    2015-09-01

    Optical discs currently on the market exhibit large variations in life span among discs, making them unsuitable for certain business applications. To assess and potentially mitigate this problem, we performed accelerated degradation testing under standard ISO conditions, determined the probable disc failure mechanisms, and identified the essential criteria necessary for a stable disc composition. With these criteria as necessary conditions, we analyzed the physical and chemical changes that occur in the disc components, on the basis of which we determined technological measures to reduce these degradation processes. By applying these measures to disc fabrication, we were able to develop highly stable optical discs.

  15. Treatment of lumbar disc herniation by percutaneous laser disc decompression (PLDD) and modified PLDD

    NASA Astrophysics Data System (ADS)

    Chi, Xiao fei; Li, Hong zhi; Wu, Ru zhou; Sui, Yun xian

    2005-07-01

    Objective: To study the micro-invasive operative method and to compare the effect of treatment of PLDD and modified PLDD for Lumbar Disc Herniation. Method: Vaporized part of the nucleus pulposus in single or multiple point after acupuncture into lumbar disc, to reach the purpose of the decompression of the lumbar disc. Result: Among the 19 cases of the regular PLDD group, the excellent and good rate was 63.2%, and among the 40 cases of the modified PLDD group, the excellent and good rate was 82.5%. Conclusion: The modified PLDD has good effect on the treatment for lumbar disc herniation.

  16. Musculoskeletal pitfalls and pseudotumours in the pelvis: a pictorial review for body imagers

    PubMed Central

    Ghazizadeh, S; Didier, R; Fung, A; Panicek, D M; Coakley, F V

    2014-01-01

    Many musculoskeletal abnormalities in the pelvis are first seen by body imagers while reviewing pelvic cross-sectional studies, and some of these abnormalities may mimic malignancy or another aggressive process. This article describes nine musculoskeletal pseudotumours and interpretative pitfalls that may be seen on CT, MRI and ultrasound imaging of the pelvis. Awareness of these pitfalls and pseudotumours may help avoid misdiagnosis and prevent inappropriate intervention or management. PMID:25096891

  17. [Spontaneous resolution of a lumbar disc herniation].

    PubMed

    Gelabert-González, M; Serramito-García, R; Aran-Echabe, E; García-Allut, A

    2007-04-01

    Lumbar disc herniation is a common cause of lower leg radiculopathy and the most effective methods of treatment remain in question. Both surgical and nonsurgical treatments may provide a successful outcome in appropriately selected patients. The spontaneous resolution of herniated lumbar discs is a well-established phenomenon. The authors present a case of spontaneous regression of a herniated lumbar nucleus pulpous in a patient with radiculopathy. PMID:17497061

  18. Disc valve for sampling erosive process streams

    DOEpatents

    Mrochek, John E.; Dinsmore, Stanley R.; Chandler, Edward W.

    1986-01-01

    A four-port disc valve for sampling erosive, high temperature process streams. A rotatable disc defining opposed first and second sampling cavities rotates between fired faceplates defining flow passageways positioned to be alternatively in axial alignment with the first and second cavities. Silicon carbide inserts and liners composed of .alpha. silicon carbide are provided in the faceplates and in the sampling cavities to limit erosion while providing lubricity for a smooth and precise operation when used under harsh process conditions.

  19. Investigation of cryogenic rupture disc design

    NASA Technical Reports Server (NTRS)

    Keough, J. B.; Oldland, A. H.

    1973-01-01

    Rupture disc designs of both the active (command actuated) and passive (pressure ruptured) types were evaluated for performance characteristics at cryogenic temperatures and for capability to operate in a variety of cryogens, including gaseous and liquid fluorine. The test results, coupled with information from literature and industry searches, were used to establish a statement of design criteria and recommended practices for application of rupture discs to cryogenic rocket propellant feed and vent systems.

  20. Mach disc formation in cylindrical recovery systems

    SciTech Connect

    Morris, C.E.; McQueen, R.G.; Marsh, S.P.

    1983-01-01

    Cylindrical recovery systems have been used to shock-load polymers to pressures exceeding 50 GPa. In order to determine the pressures generated in these recovery systems the formation of the Mach disc on axis and its approach to steady state was monitored. The relation of the Mach disc diameter to the lateral dimension of the high explosive used to compress the polymer samples was also investigated.

  1. ARRANGEMENT FOR REPLACING FILTERS

    DOEpatents

    Blomgren, R.A.; Bohlin, N.J.C.

    1957-08-27

    An improved filtered air exhaust system which may be continually operated during the replacement of the filters without the escape of unfiltered air is described. This is accomplished by hermetically sealing the box like filter containers in a rectangular tunnel with neoprene covered sponge rubber sealing rings coated with a silicone impregnated pneumatic grease. The tunnel through which the filters are pushed is normal to the exhaust air duct. A number of unused filters are in line behind the filters in use, and are moved by a hydraulic ram so that a fresh filter is positioned in the air duct. The used filter is pushed into a waiting receptacle and is suitably disposed. This device permits a rapid and safe replacement of a radiation contaminated filter without interruption to the normal flow of exhaust air.

  2. Celotex (Registered) Replacement Study

    SciTech Connect

    Couture, S; Hafner, R

    2002-10-01

    The AL-R8 is the pit storage container in most widespread use at Pantex. The AL-R8 container family consists of standard 20-in.-diameter steel drums, 30 to 60 in. in height, with insulation inserts made of Celotex{reg_sign}--a fiberboard product made from processed sugar cane. Celotex is an acceptable material for inserts in many radioactive material shipping and storage containers. It is a good shock mitigator/insulator, does a fair job in fire protection (when oxygen is excluded), shielding, and criticality, and is inexpensive and easily available. However, the fiberboard absorbs water in humid environments which, when combined with chemical residues in the fiberboard, forms corrosive compounds that can shorten the life of the container and affect container contents. To protect the contents from this potentially damaging environment, the AL-R8 SI was developed to isolate the contents within a sealed stainless steel vessel inside the AL-R8. Although the SI protected the contents, corrosion studies indicated the SI lid bolts might corrode over time and surveillance showed that areas of the outer drum were still subject to corrosion. To address this potential problem, DOE/Albuquerque sponsored bolt and Celotex replacement studies. The bolt replacement study was assigned to Mason and Hanger's Pantex Facility and this Celotex Replacement Study to Lawrence Livermore National Laboratory. The Celotex Replacement Study evaluated options for replacing Celotex with a material that is chemically compatible with the AL-R8 SI container. The evaluation was limited to materials either used previously in nuclear materials shipping and storage containers or materials with known properties in a low-radiation environment. This limitation was set to ensure that the long-term aging effect on the new material is known a priori. Initial material evaluations narrowed the material choices to foam and cork. Although cork performed better than foam in some tests, cork was considered a less

  3. NARC Rayon Replacement Program

    NASA Technical Reports Server (NTRS)

    Wilson, Kenneth P.; McCool, Alex (Technical Monitor)

    2002-01-01

    This viewgraph presentation provides information on the search for a replacement product for the aerospace grade rayon formerly used in the reusable solid rocket motor (RSRM). The rayon used in RSRMs is no longer produced by the North American Rayon Corporation (NARC), though NASA has stockpiled rayon to be used until a suitable replacement is found to be used in the RSRM nozzle carbon cloth phenolic (CCP). The primary considerations are performance, process ability, variability, long term availability, and cost. The preference will be given to commercial off-the-shelf products as opposed to those which are custom made. The candidate materials have been tested in previous phases of this selection process, and Enka Textile Rayon has emerged as a possible fabric, though its availability is still in question.

  4. Discovery of the Fomalhaut C debris disc

    NASA Astrophysics Data System (ADS)

    Kennedy, G. M.; Wyatt, M. C.; Kalas, P.; Duchêne, G.; Sibthorpe, B.; Lestrade, J.-F.; Matthews, B. C.; Greaves, J.

    2014-02-01

    Fomalhaut is one of the most interesting and well-studied nearby stars, hosting at least one planet, a spectacular debris ring and two distant low-mass stellar companions (TW PsA and LP 876-10, a.k.a. Fomalhaut B and C). We observed both companions with Herschel, and while no disc was detected around the secondary, TW PsA, we have discovered the second debris disc in the Fomalhaut system, around LP 876-10. This detection is only the second case of two debris discs seen in a multiple system, both of which are relatively wide (≳3000 au for HD 223352/40 and 158 kau [0.77 pc] for Fomalhaut/LP 876-10). The disc is cool (24 K) and relatively bright, with a fractional luminosity Ldisc/L⋆ = 1.2 × 10-4, and represents the rare observation of a debris disc around an M dwarf. Further work should attempt to find if the presence of two discs in the Fomalhaut system is coincidental, perhaps simply due to the relatively young system age of 440 Myr, or if the stellar components have dynamically interacted and the system is even more complex than it currently appears.

  5. Proteomic Signature of the Murine Intervertebral Disc

    PubMed Central

    McCann, Matthew R.; Patel, Priya; Frimpong, Agya; Xiao, Yizhi; Siqueira, Walter L.; Séguin, Cheryle A.

    2015-01-01

    Low back pain is the most common musculoskeletal problem and the single most common cause of disability, often attributed to degeneration of the intervertebral disc. Lack of effective treatment is directly related to our limited understanding of the pathways responsible for maintaining disc health. While transcriptional analysis has permitted initial insights into the biology of the intervertebral disc, complete proteomic characterization is required. We therefore employed liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) protein/peptide separation and mass spectrometric analyses to characterize the protein content of intervertebral discs from skeletally mature wild-type mice. A total of 1360 proteins were identified and categorized using PANTHER. Identified proteins were primarily intracellular/plasma membrane (35%), organelle (30%), macromolecular complex (10%), extracellular region (9%). Molecular function categorization resulted in three distinct categories: catalytic activity (33%), binding (molecule interactions) (29%), and structural activity (13%). To validate our list, we confirmed the presence of 14 of 20 previously identified IVD-associated markers, including matrix proteins, transcriptional regulators, and secreted proteins. Immunohistochemical analysis confirmed distinct localization patterns of select protein with the intervertebral disc. Characterization of the protein composition of healthy intervertebral disc tissue is an important first step in identifying cellular processes and pathways disrupted during aging or disease progression. PMID:25689066

  6. Modeling Jupiter's current disc: Pioneer 10 outbound

    SciTech Connect

    Jones, D.E.; Melville, J.G. II; Blake, M.L.

    1980-07-01

    The magnetic field of the Jovian current disc has been modeled by using Euler functions and the Biot-Savart law applied to a series of concentric, but not necessarily coplanar, current rings. We find that a best fit to the Pioneer 10 outbound perturbation magnetic field data (B/sub total/-B/sub dipole/) is obtained if the current disc is twisted (outer edges increasingly lag behind inner edges with radial distance) and also bent so as to tend toward parallelism with the Jovigraphic equator. The inner and outer radii of the disc appear to be about 7 R/sub J/ and 150 R/sub J/, respectively, although some indication of a changing magnetopause location is apparent in the data. Because of the observed current disc penetrations, the bent disc also requires a deformation in the form of a bump or wrinkle whose axis tends also to exhibit spiraling. The radial dependence of the azimuthal current in the disc is not described by a simple power law, the outer region showing a smaller power law dependence. Modeling of the azimuthal field shows it to be due to a thin radial current sheet, but there is some evidence that this may, in fact, be due in large part to penetration of a tail current sheet as suggested by the Voyager observations.

  7. Optic disc anomalies and frontonasal dysplasia

    PubMed Central

    Hodgkins, P; Lees, M; Lawson, J; Reardon, W; Leitch, J; Thorogood, P; Winter, R; Taylor, D

    1998-01-01

    AIMS—To document the optic disc abnormalities in patients with frontonasal dysplasia in association with basal encephalocele.
METHODS—Names and hospital numbers of patients with midline clefts were obtained from the ophthalmology and genetics database. Six patients were identified who had the following common findings: midline facial cleft with midline cleft lip and palate; hypertelorism; absent corpus callosum; basal (sphenoethmoidal) encephalocele; and pituitary deficiency (five out of six cases). Ophthalmic examination was performed with fundal photography where possible.
RESULTS—Two patients had unilateral and one a bilateral peripapillary staphyloma. Two patients had bilateral optic disc hypoplasia and one appeared to have a peripapillary staphyloma in one eye and a morning glory disc in the other.
CONCLUSION—Optic disc abnormalities were found in all patients with this constellation of clinical findings. This association appears to represent a distinct subgroup within the spectrum of frontonasal dysplasia. The presence of midline facial anomalies and any dysplastic disc should alert the physician as to the presence of an encephalocele.

 Keywords: frontonasal dysplasia; optic disc; encephalocele PMID:9602627

  8. The diversity of thick galactic discs

    NASA Astrophysics Data System (ADS)

    Kasparova, Anastasia V.; Katkov, Ivan Yu.; Chilingarian, Igor V.; Silchenko, Olga K.; Moiseev, Alexey V.; Borisov, Svyatoslav B.

    2016-07-01

    Although thick stellar discs are detected in nearly all edge-on disc galaxies, their formation scenarios still remain a matter of debate. Due to observational difficulties, there is a lack of information about their stellar populations. Using the Russian 6-m telescope BTA we collected deep spectra of thick discs in three edge-on S0-a disc galaxies located in different environments: NGC 4111 in a dense group, NGC 4710 in the Virgo cluster, and NGC 5422 in a sparse group. We see intermediate age (4-5 Gyr) metal rich ([Fe/H] ˜- 0.2…0.0 dex) stellar populations in NGC 4111 and NGC 4710. On the other hand, NGC 5422 does not harbour young stars, its disc is thick and old (10 Gyr), without evidence for a second component, and its α-element abundance suggests a 1.5-2 Gyr long formation epoch implying its formation at high redshift. Our results suggest the diversity of thick disc formation scenarios.

  9. Circumplanetary disc or circumplanetary envelope?

    NASA Astrophysics Data System (ADS)

    Szulágyi, J.; Masset, F.; Lega, E.; Crida, A.; Morbidelli, A.; Guillot, T.

    2016-08-01

    We present three-dimensional simulations with nested meshes of the dynamics of the gas around a Jupiter mass planet with the JUPITER and FARGOCA codes. We implemented a radiative transfer module into the JUPITER code to account for realistic heating and cooling of the gas. We focus on the circumplanetary gas flow, determining its characteristics at very high resolution (80 per cent of Jupiter's diameter). In our nominal simulation where the temperature evolves freely by the radiative module and reaches 13000 K at the planet, a circumplanetary envelope was formed filling the entire Roche lobe. Because of our equation of state is simplified and probably overestimates the temperature, we also performed simulations with limited maximal temperatures in the planet region (1000, 1500, and 2000 K). In these fixed temperature cases circumplanetary discs (CPDs) were formed. This suggests that the capability to form a CPD is not simply linked to the mass of the planet and its ability to open a gap. Instead, the gas temperature at the planet's location, which depends on its accretion history, plays also fundamental role. The CPDs in the simulations are hot and cooling very slowly, they have very steep temperature and density profiles, and are strongly sub-Keplerian. Moreover, the CPDs are fed by a strong vertical influx, which shocks on the CPD surfaces creating a hot and luminous shock-front. In contrast, the pressure supported circumplanetary envelope is characterized by internal convection and almost stalled rotation.

  10. Renal Replacement Therapy.

    PubMed

    Ricci, Zaccaria; Romagnoli, Stefano; Ronco, Claudio

    2016-01-01

    During the last few years, due to medical and surgical evolution, patients with increasingly severe diseases causing multiorgan dysfunction are frequently admitted to intensive care units. Therapeutic options, when organ failure occurs, are frequently nonspecific and mostly directed towards supporting vital function. In these scenarios, the kidneys are almost always involved and, therefore, renal replacement therapies have become a common routine practice in critically ill patients with acute kidney injury. Recent technological improvement has led to the production of safe, versatile and efficient dialysis machines. In addition, emerging evidence may allow better individualization of treatment with tailored prescription depending on the patients' clinical picture (e.g. sepsis, fluid overload, pediatric). The aim of the present review is to give a general overview of current practice in renal replacement therapies for critically ill patients. The main clinical aspects, including dose prescription, modality of dialysis delivery, anticoagulation strategies and timing will be addressed. In addition, some technical issues on physical principles governing blood purification, filters characteristics, and vascular access, will be covered. Finally, a section on current standard nomenclature of renal replacement therapy is devoted to clarify the "Tower of Babel" of critical care nephrology. PMID:26918174

  11. Renal Replacement Therapy

    PubMed Central

    Ricci, Zaccaria; Romagnoli, Stefano; Ronco, Claudio

    2016-01-01

    During the last few years, due to medical and surgical evolution, patients with increasingly severe diseases causing multiorgan dysfunction are frequently admitted to intensive care units. Therapeutic options, when organ failure occurs, are frequently nonspecific and mostly directed towards supporting vital function. In these scenarios, the kidneys are almost always involved and, therefore, renal replacement therapies have become a common routine practice in critically ill patients with acute kidney injury. Recent technological improvement has led to the production of safe, versatile and efficient dialysis machines. In addition, emerging evidence may allow better individualization of treatment with tailored prescription depending on the patients’ clinical picture (e.g. sepsis, fluid overload, pediatric). The aim of the present review is to give a general overview of current practice in renal replacement therapies for critically ill patients. The main clinical aspects, including dose prescription, modality of dialysis delivery, anticoagulation strategies and timing will be addressed. In addition, some technical issues on physical principles governing blood purification, filters characteristics, and vascular access, will be covered. Finally, a section on current standard nomenclature of renal replacement therapy is devoted to clarify the “Tower of Babel” of critical care nephrology. PMID:26918174

  12. Polyurethane scaffold with in situ swelling capacity for nucleus pulposus replacement.

    PubMed

    Li, Zhen; Lang, Gernot; Chen, Xu; Sacks, Hagit; Mantzur, Carmit; Tropp, Udi; Mader, Kerstin T; Smallwood, Thomas C; Sammon, Chris; Richards, R Geoff; Alini, Mauro; Grad, Sibylle

    2016-04-01

    Nucleus pulposus (NP) replacement offers a minimally invasive alternative to spinal fusion or total disc replacement for the treatment of intervertebral disc (IVD) degeneration. This study aimed to develop a cytocompatible NP replacement material, which is feasible for non-invasive delivery and tunable design, and allows immediate mechanical restoration of the IVD. A bi-phasic polyurethane scaffold was fabricated consisting of a core material with rapid swelling property and a flexible electrospun envelope. The scaffold was assessed in a bovine whole IVD organ culture model under dynamic load for 14 days. Nucleotomy was achieved by incision through the endplate without damaging the annulus fibrosus. After implantation of the scaffold and in situ swelling, the dynamic compressive stiffness and disc height were restored immediately. The scaffold also showed favorable cytocompatibility for native disc cells. Implantation of the scaffold in a partially nucleotomized IVD down-regulated catabolic gene expression, increased proteoglycan and type II collagen intensity and decreased type I collagen intensity in remaining NP tissue, indicating potential to retard degeneration and preserve the IVD cell phenotype. The scaffold can be delivered in a minimally invasive manner, and the geometry of the scaffold post-hydration is tunable by adjusting the core material, which allows individualized design. PMID:26828684

  13. Percutaneous Disc Coagulation Therapy (PDCT) comparing with Automated Percutaneous Lumbar Discectomy (APLD) in Patients of Herniated Lumbar Disc Disease: Preliminary Report

    PubMed Central

    Park, Cheon Wook; Lee, Joo Yong; Choi, Woo Jin

    2012-01-01

    Objective Percutaneous techniques are rapidly replacing traditional open surgery. This is a randomized controlled trial study of clinical outcomes of Percutaneous Plasma Disc Coagulation Therapy (PDCT) in patients with HLD(herniated lumbar disc) as a new percutaneous access in comparison with Automated Percutaneous Lumbar Discectomy (APLD) in its clinical application and usefulness as a reliable alternative method. Methods The authors analyzed 25 patients who underwent PDCT randomized 1:1 to 25 who underwent APLD between June, 2010 and October, 2011. All patients had herniated lumbar disc diseases. The clinical outcomes were evaluated using Visual Analog Scales (VAS) score and MacNab's criteria. Results The age of the patients who underwent PDCT ranged from 29 to 88 years with a mean age of 51.8 years. The age of the APLD undergone patients' population ranged from 30 to 66 with a mean age of 46.0 years. The average preoperative VAS score in PDCT was 7.60 and 1.94 at 7months post-operatively, and in APLD was 7.32, and 3.53 at 7 months post-operatively (p<0.001). In Macnab's criteria, 20 patients (80%) had achieved favorable improvement (excellent and good) in PDCT group. In Macnab's criteria, 16 patients (64%) had achieved favorable improvement in APLD group (p<0.001). Conclusion PDCT can be considered a viable option as a new percutaneous access to herniated lumbar disc. PDCT showed to be more effective than APLD in this study, allowing stable decompression and safe minimally invasive operation to an area desired by the operator in lumbar disc herniation patients, although further long term clinical evaluations are still necessary. PMID:25983808

  14. Tracing Planets in Circumstellar Discs. Observability of Large-scale Disc Structures with ALMA

    NASA Astrophysics Data System (ADS)

    Ruge, Jan Philipp; Wolf, Sebastian; Uribe, Ana L.; Klahr, Hubert H.

    2013-04-01

    Planets are assumed to form in circumstellar discs around young stellar objects. The additional gravitational potential of a planet perturbs the disc and leads to characteristic structures, i.e. spiral waves and gaps, in the disc density profile. We perform a large-scale parameter study on the observability of these planet-induced structures in circumstellar discs in the (sub)mm wavelength range for the Atacama Large (Sub)Millimeter Array (ALMA). On the basis of hydrodynamical and magneto-hydrodynamical simulations of star-disc-planet models we calculate the disc temperature structure and (sub)mm images of these systems. These are used to derive simulated ALMA maps. Because appropriate objects are frequent in the Taurus-Auriga region, we focus on a distance of 140 pc and a declination of ≈ 20°. The explored range of star-disc-planet configurations consists of six hydrodynamical simulations (including magnetic fields and different planet masses), nine disc sizes with outer radii ranging from 9 AU to 225 AU, 15 total disc masses in the range between 2.67·10-7 M⊙ and 4.10·10-2 M⊙, six different central stars and two different grain size distributions, resulting in 10 000 disc models. At almost all scales and in particular down to a scale of a few AU, ALMA is able to trace disc structures induced by planet-disc interaction or the influence of magnetic fields in the wavelength range between 0.4...2.0 mm. In most cases, the optimum angular resolution is limited by the sensitivity of ALMA. However, within the range of typical masses of protoplane tary discs (0.1 M⊙...0.001 M⊙) the disc mass has a minor impact on the observability. At the distance of 140 pc it is possible to resolve discs down to 2.67·10-6 M⊙ and trace gaps in discs with 2.67·10-4 M⊙ with a signal-to-noise ratio greater than three. In general, it is more likely to trace planet-induced gaps in magneto-hydrodynamical disc models, because gaps are wider in the presence of magnetic fields [1

  15. The pitfalls of field trials in fish vaccinology.

    PubMed

    Mitchell, H

    1997-01-01

    Field trials are essential for accurately assessing the worth of a vaccine under actual conditions of use. Compared with the laboratory, the dynamics of the host, pathogen, and environment in a production setting can produce both subtle and dramatic differences on the performance of the vaccine and the immune response. Because of this, field trials are conducted by manufacturers in vaccine development and are required by many national regulatory agencies to evaluate safety and/or efficacy before granting vaccine licenses. Aquaculture producers, veterinarians and fish health professionals can use field trials to analyse the cost-benefit of a vaccination programme for a facility, or to compare competitive products. Vaccine field trials are more than merely using the products in the field. Small efficacy effects can result in considerable cost reductions to the fish farmer. Proper field trial design, conduct and analysis is critical to detecting these effects. However, field trials are also fraught with many pitfalls that can result in failure or misleading conclusions. The discussion regarding possible pitfalls of vaccine field trials in aquaculture is divided into two parts: 1) the art and 2) the science of successful field trials. The art of successful field trials involves dealing with the "people" aspect which is necessary for initial and continuing compliance. Meticulous planning is essential, including a written protocol to which everyone agrees by signature. The bottom line to the art of field trials is anticipation and discussion of all possible eventualities together with constant communication with the farmer and site supervisor. The science of successful fields trials involves anticipating and realizing the logistical and statistical difficulties in design and implementation. Problems often encountered are: lack of stated quantifiable purpose; low power of the test due to inherent small sample size, large variation and small margin of effect; lack of

  16. Modeling and optimization of an elastic arthroplastic disc for a degenerated disc

    NASA Astrophysics Data System (ADS)

    Ghouchani, Azadeh; Ravari, Mohammad; Mahmoudi, Farid

    2011-10-01

    A three-dimensional finite element model (FEM) of the L3-L4 motion segment using ABAQUS v 6.9 has been developed. The model took into account the material nonlinearities and is imposed different loading conditions. In this study, we validated the model by comparison of its predictions with several sets of experimental data. Disc deformation under compression and segmental rotational motions under moment loads for the normal disc model agreed well with the corresponding in vivo studies. By linking ABAQUS with MATLAB 2010.a, we determined the optimal Young s modulus as well as the Poisson's ratio for the artificial disc under different physiologic loading conditions. The results of the present study confirmed that a well-designed elastic arthroplastic disc preferably has an annulus modulus of 19.1 MPa and 1.24 MPa for nucleus section and Poisson ratio of 0.41 and 0.47 respectively. Elastic artificial disc with such properties can then achieve the goal of restoring the disc height and mechanical function of intact disc under different loading conditions and so can reduce low back pain which is mostly caused due to disc degeneration.

  17. Preparation of ormetoprim-sulfadimethoxine-medicated discs for disc diffusion assay

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Romet ( a blend of ormetoprim and sulfadimethoxine) is a type A medicated article for the manufacture of medicated feed in the catfish industry. Recently, the commercial manufacture of ormetoprim-sulfadimethoxine susceptibility discs was discontinued. Ormetoprim-sulfadimethoxine discs were prepare...

  18. Structures induced by companions in galactic discs

    NASA Astrophysics Data System (ADS)

    Kyziropoulos, P. E.; Efthymiopoulos, C.; Gravvanis, G. A.; Patsis, P. A.

    2016-09-01

    Using N-body simulations we study the structures induced on a galactic disc by repeated flybys of a companion in decaying eccentric orbit around the disc. Our system is composed by a stellar disc, bulge and live dark matter halo, and we study the system's dynamical response to a sequence of a companion's flybys, when we vary i) the disc's temperature (parameterized by Toomre's Q-parameter) and ii) the companion's mass and initial orbit. We use a new 3D Cartesian grid code: MAIN (Mesh-adaptive Approximate Inverse N-body solver). The main features of MAIN are reviewed, with emphasis on the use of a new Symmetric Factored Approximate Sparse Inverse (SFASI) matrix in conjunction with the multigrid method that allows the efficient solution of Poisson's equation in three space variables. We find that: i) companions need to be assigned initial masses in a rather narrow window of values in order to produce significant and more long-standing non-axisymmetric structures (bars and spirals) in the main galaxy's disc by the repeated flyby mechanism. ii) a crucial phenomenon is the antagonism between companion-excited and self-excited modes on the disc. Values of Q > 1.5 are needed in order to allow for the growth of the companion-excited modes to prevail over the the growth of the disc's self-excited modes. iii) We give evidence that the companion-induced spiral structure is best represented by a density wave with pattern speed nearly constant in a region extending from the ILR to a radius close to, but inside, corotation.

  19. Cervical disc hernia operations through posterior laminoforaminotomy

    PubMed Central

    Yolas, Coskun; Ozdemir, Nuriye Guzin; Okay, Hilmi Onder; Kanat, Ayhan; Senol, Mehmet; Atci, Ibrahim Burak; Yilmaz, Hakan; Coban, Mustafa Kemal; Yuksel, Mehmet Onur; Kahraman, Umit

    2016-01-01

    Objective: The most common used technique for posterolateral cervical disc herniations is anterior approach. However, posterior cervical laminotoforaminomy can provide excellent results in appropriately selected patients with foraminal stenosis in either soft disc prolapse or cervical spondylosis. The purpose of this study was to present the clinical outcomes following posterior laminoforaminotomy in patients with radiculopathy. Materials and Methods: We retrospectively evaluated 35 patients diagnosed with posterolateral cervical disc herniation and cervical spondylosis with foraminal stenosis causing radiculopathy operated by the posterior cervical keyhole laminoforaminotomy between the years 2010 and 2015. Results: The file records and the radiographic images of the 35 patients were assessed retrospectively. The mean age was 46.4 years (range: 34-66 years). Of the patients, 19 were males and 16 were females. In all of the patients, the neurologic deficit observed was radiculopathy. The posterolaterally localized disc herniations and the osteophytic structures were on the left side in 18 cases and on the right in 17 cases. In 10 of the patients, the disc level was at C5-6, in 18 at C6-7, in 2 at C3-4, in 2 at C4-5, in 1 at C7-T1, in 1 patient at both C5-6 and C6-7, and in 1 at both C4-5 and C5-6. In 14 of these 35 patients, both osteophytic structures and protruded disc herniation were present. Intervertebral foramen stenosis was present in all of the patients with osteophytes. Postoperatively, in 31 patients the complaints were relieved completely and four patients had complaints of neck pain and paresthesia radiating to the arm (the success of operation was 88.5%). On control examinations, there was no finding of instability or cervical kyphosis. Conclusion: Posterior cervical laminoforaminotomy is an alternative appropriate choice in both cervical soft disc herniations and cervical stenosis. PMID:27217655

  20. Thyroid hormone replacement therapy.

    PubMed

    Wiersinga, W M

    2001-01-01

    Thyroid hormone replacement has been used for more than 100 years in the treatment of hypothyroidism, and there is no doubt about its overall efficacy. Desiccated thyroid contains both thyroxine (T(4)) and triiodothyronine (T(3)); serum T(3) frequently rises to supranormal values in the absorption phase, associated with palpitations. Liothyronine (T(3)) has the same drawback and requires twice-daily administration in view of its short half-life. Synthetic levothyroxine (L-T(4)) has many advantages: in view of its long half-life, once-daily administration suffices, the occasional missing of a tablet causes no harm, and the extrathyroidal conversion of T(4) into T(3) (normally providing 80% of the daily T(3) production rate) remains fully operative, which may have some protective value during illness. Consequently, L-T(4) is nowadays preferred, and its long-term use is not associated with excess mortality. The mean T(4) dose required to normalize serum thyroid stimulating hormone (TSH) is 1.6 microg/kg per day, giving rise to serum free T(4) (fT(4)) concentrations that are slightly elevated or in the upper half of the normal reference range. The higher fT(4) values are probably due to the need to generate from T(4) the 20% of the daily T(3) production rate that otherwise is derived from the thyroid gland itself. The daily maintenance dose of T(4) varies widely between 75 and 250 microg. Assessment of the appropriate T(4) dose is by assay of TSH and fT(4), preferably in a blood sample taken before ingestion of the subsequent T(4) tablet. Dose adjustments can be necessary in pregnancy and when medications are used that are known to interfere with the absorption or metabolism of T(4). A new equilibrium is reached after approximately 6 weeks, implying that laboratory tests should not be done earlier. With a stable maintenance dose, an annual check-up usually suffices. Accumulated experience with L-T(4) replacement has identified some areas of concern. First, the

  1. Reconstructing the star formation history of the Milky Way disc(s) from chemical abundances

    NASA Astrophysics Data System (ADS)

    Snaith, O.; Haywood, M.; Di Matteo, P.; Lehnert, M. D.; Combes, F.; Katz, D.; Gómez, A.

    2015-06-01

    We develop a chemical evolution model to study the star formation history of the Milky Way. Our model assumes that the Milky Way has formed from a closed-box-like system in the inner regions, while the outer parts of the disc have experienced some accretion. Unlike the usual procedure, we do not fix the star formation prescription (e.g. Kennicutt law) to reproduce the chemical abundance trends. Instead, we fit the abundance trends with age to recover the star formation history of the Galaxy. Our method enables us to recover the star formation history of the Milky Way in the first Gyrs with unprecedented accuracy in the inner (R < 7-8 kpc) and outer (R > 9-10 kpc) discs, as sampled in the solar vicinity. We show that half the stellar mass formed during the thick-disc phase in the inner galaxy during the first 4-5 Gyr. This phase was followed by a significant dip in star formation activity (at 8-9 Gyr) and a period of roughly constant lower-level star formation for the remaining 8 Gyr. The thick-disc phase has produced as many metals in 4 Gyr as the thin-disc phase in the remaining 8 Gyr. Our results suggest that a closed-box model is able to fit all the available constraints in the inner disc. A closed-box system is qualitatively equivalent to a regime where the accretion rate maintains a high gas fraction in the inner disc at high redshift. In these conditions the SFR is mainly governed by the high turbulence of the interstellar medium. By z ~ 1 it is possible that most of the accretion takes place in the outer disc, while the star formation activity in the inner disc is mostly sustained by the gas that is not consumed during the thick-disc phase and the continuous ejecta from earlier generations of stars. The outer disc follows a star formation history very similar to that of the inner disc, although initiated at z ~ 2, about 2 Gyr before the onset of the thin-disc formation in the inner disc.

  2. Tearing up the disc: misaligned accretion on to a binary

    NASA Astrophysics Data System (ADS)

    Nixon, Chris; King, Andrew; Price, Daniel

    2013-09-01

    In a recent paper, we have shown that the evolution of a misaligned disc around a spinning black hole can result in tearing the disc into many distinct planes. Tearing discs with random orientations produce direct dynamical accretion on to the hole in ≈70 per cent of all cases. Here, we examine the evolution of a misaligned disc around a binary system. We show that these discs are susceptible to tearing for almost all inclinations. We also show that tearing of the disc can result in a significant acceleration of the disc evolution and subsequent accretion on to the binary - by factors up to 104 times that of a coplanar prograde disc with otherwise identical parameters. This provides a promising mechanism for driving mergers of supermassive black hole (SMBH) binaries on time-scales much shorter than a Hubble time. Disc tearing also suggests new observational signatures of accreting SMBH binaries and other systems such as protostellar binaries.

  3. Disc-shaped colloids interacting in a nematic liquid crystal

    NASA Astrophysics Data System (ADS)

    Antipova, Alena; Denniston, Colin

    2014-11-01

    We studied the behavior of pairs of disc-shaped colloidal particles in a nematic liquid crystal using Lattice Boltzmann algorithm. Without any external forces the position of the disc with respect to the liquid crystal director minimizes the free energy of the system and no distortion of the director field is observed. When the rotating magnetic field is present, the torque on the disc with homeotropic surface anchoring should change with analogy to electrostatic energy, which implies the disc continues turning following the field. However, when the disc reaches some critical position and the director field around it is highly distorted, the disc suddenly flips to minimize the free energy. Position and motion of pairs of such discs under similar conditions can be controlled by the angular velocity of magnetic field, it's magnitude and initial configuration of the system. As a result of analysis of discs' dynamics, a new way to control self-organization of disc particles was produced.

  4. Renal Replacement Therapy.

    PubMed

    Villa, Gianluca; Ricci, Zaccaria; Ronco, Claudio

    2015-10-01

    Renal replacement therapy (RRT) is a cornerstone in the clinical management of patients with acute kidney injury. Results from different studies agree that early renal support therapy (aimed to support the residual kidney function during early phases of organ dysfunction) may reduce mortality with respect to late RRT (aimed to substitute the complete loss of function during the advanced kidney insufficiency). Although it seems plausible that a timely initiation of RRT may be associated with improved renal and nonrenal outcomes in these patients, there is scarce evidence in literature to exactly identify the most adequate onset timing for RRT. PMID:26410148

  5. Immediate total tooth replacement.

    PubMed

    Garber, D A; Salama, M A; Salama, H

    2001-03-01

    Successful implant placement at the time of extraction has been documented. Implant placement at the time of extraction was initially performed as a two-stage procedure often with barrier membranes and sophisticated second-stage surgical uncoverings. The authors describe the next generation of this technique, including atraumatic tooth removal with simultaneous root form, implant placement, and temporization at one appointment. This technique of "Immediate Total Tooth Replacement" allows for the maintenance of the bony housing and soft-tissue form that existed before extraction, while at the same time establishing a root form anchor in the bone for an esthetic restoration. PMID:11913258

  6. Optic disc segmentation by balloon snake with texture from color fundus image.

    PubMed

    Sun, Jinyang; Luan, Fangjun; Wu, Hanhui

    2015-01-01

    A well-established method for diagnosis of glaucoma is the examination of the optic nerve head based on fundus image as glaucomatous patients tend to have larger cup-to-disc ratios. The difficulty of optic segmentation is due to the fuzzy boundaries and peripapillary atrophy (PPA). In this paper a novel method for optic nerve head segmentation is proposed. It uses template matching to find the region of interest (ROI). The method of vessel erasing in the ROI is based on PDE inpainting which will make the boundary smoother. A novel optic disc segmentation approach using image texture is explored in this paper. A cluster method based on image texture is employed before the optic disc segmentation step to remove the edge noise such as cup boundary and vessels. We replace image force in the snake with image texture and the initial contour of the balloon snake is inside the optic disc to avoid the PPA. The experimental results show the superior performance of the proposed method when compared to some traditional segmentation approaches. An average segmentation dice coefficient of 94% has been obtained. PMID:25861249

  7. Optic Disc Segmentation by Balloon Snake with Texture from Color Fundus Image

    PubMed Central

    Sun, Jinyang; Luan, Fangjun; Wu, Hanhui

    2015-01-01

    A well-established method for diagnosis of glaucoma is the examination of the optic nerve head based on fundus image as glaucomatous patients tend to have larger cup-to-disc ratios. The difficulty of optic segmentation is due to the fuzzy boundaries and peripapillary atrophy (PPA). In this paper a novel method for optic nerve head segmentation is proposed. It uses template matching to find the region of interest (ROI). The method of vessel erasing in the ROI is based on PDE inpainting which will make the boundary smoother. A novel optic disc segmentation approach using image texture is explored in this paper. A cluster method based on image texture is employed before the optic disc segmentation step to remove the edge noise such as cup boundary and vessels. We replace image force in the snake with image texture and the initial contour of the balloon snake is inside the optic disc to avoid the PPA. The experimental results show the superior performance of the proposed method when compared to some traditional segmentation approaches. An average segmentation dice coefficient of 94% has been obtained. PMID:25861249

  8. A test of truncation in the accretion discs of X-ray Binaries.

    NASA Astrophysics Data System (ADS)

    Eckersall, A.

    2016-06-01

    The truncated-disc model is generally used to help explain the change between the soft and hard states in X-ray Binaries, where the standard accretion disc is truncated in the inner regions and replaced by a radiatively inefficient accretion flow. There is still disagreement though in the extent of this truncation, particularly in at what point truncation begins. Here we analyze XMM EPIC-pn spectra in both the soft and hard states for a number of galactic XRBs, along with RGS data and the latest absorption and emission models to get an independent fit for the ISM column densities for each source. Specifically, we assume the 'canonical' model where the luminous accretion disc extends down to the innermost stable orbit at 6r_g, and construct a spectral model accounting for thermal, reflection and Compton processes ensuring consistent geometrical properties of the models. Rather than attempting to infer the inner disc location from spectral fitting and/or reflection models, we instead attempt a direct test of whether a consistent model will fit assuming no truncation. We discuss the implications for emission models of XRBs.

  9. Bed bug (Heteroptera: Cimicidae) attraction to pitfall traps baited with carbon dioxide, heat, and chemical lure.

    PubMed

    Wang, Changlu; Gibb, Timothy; Bennett, Gary W; McKnight, Susan

    2009-08-01

    Carbon dioxide (CO2), heat, and chemical lure (1-octen-3-ol and L-lactic acid) were tested as attractants for bed bugs, Cimex lectularius L. (Heteroptera: Cimicidae), by using pitfall traps. Both CO2 and heat were attractive to bed bugs. CO2 was significantly more attractive to bed bugs than heat. Traps baited with chemical lure attracted more bed bugs but at a statistically nonsignificant level. In small arena studies (56 by 44 cm), pitfall traps baited with CO2 or heat trapped 79.8 +/- 6.7 and 51.6 +/- 0.9% (mean +/- SEM) of the bed bugs after 6 h, respectively. Traps baited with CO2 + heat, CO, + chemical lure, or CO2 + heat + chemical lure captured > or = 86.7% of the bed bugs after 6 h, indicating baited pitfall traps were highly effective in attracting and capturing bed bugs from a short distance. In 3.1- by 1.8-m environmental chambers, a pitfall trap baited with CO, + heat + chemical lure trapped 57.3 +/- 6.4% of the bed bugs overnight. The pitfall trap was further tested in four bed bug-infested apartments to determine its efficacy in detecting light bed bug infestations. Visual inspections found an average of 12.0 +/- 5.4 bed bugs per apartment. The bed bugs that were found by visual inspections were hand-removed during inspections. A pitfall trap baited with CO2 and chemical lure was subsequently placed in each apartment with an average of 15.0 +/- 6.4 bed bugs collected per trap by the next morning. We conclude that baited pitfall traps are potentially effective tools for evaluating bed bug control programs and detecting early bed bug infestations. PMID:19736771

  10. Cadmium plating replacements

    SciTech Connect

    Nelson, M.J.; Groshart, E.C.

    1995-03-01

    The Boeing Company has been searching for replacements to cadmium plate. Two alloy plating systems seem close to meeting the needs of a cadmium replacement. The two alloys, zinc-nickel and tin-zinc are from alloy plating baths; both baths are neutral pH. The alloys meet the requirements for salt fog corrosion resistance, and both alloys excel as a paint base. Currently, tests are being performed on standard fasteners to compare zinc-nickel and tin-zinc on threaded hardware where cadmium is heavily used. The Hydrogen embrittlement propensity of the zinc-nickel bath has been tested, and just beginning for the tin-zinc bath. Another area of interest is the electrical properties on aluminum for tin-zinc and will be discussed. The zinc-nickel alloy plating bath is in production in Boeing Commercial Airplane Group for non-critical low strength steels. The outlook is promising that these two coatings will help The Boeing Company significantly reduce its dependence on cadmium plating.

  11. Sutureless aortic valve replacement

    PubMed Central

    Phan, Kevin

    2015-01-01

    The increasing incidence of aortic stenosis and greater co-morbidities and risk profiles of the contemporary patient population has driven the development of minimally invasive aortic valve surgery and percutaneous transcatheter aortic valve implantation (TAVI) techniques to reduce surgical trauma. Recent technological developments have led to an alternative minimally invasive option which avoids the placement and tying of sutures, known as “sutureless” or rapid deployment aortic valves. Potential advantages for sutureless aortic prostheses include reducing cross-clamp and cardiopulmonary bypass (CPB) duration, facilitating minimally invasive surgery and complex cardiac interventions, whilst maintaining satisfactory hemodynamic outcomes and low paravalvular leak rates. However, given its recent developments, the majority of evidence regarding sutureless aortic valve replacement (SU-AVR) is limited to observational studies and there is a paucity of adequately-powered randomized studies. Recently, the International Valvular Surgery Study Group (IVSSG) has formulated to conduct the Sutureless Projects, set to be the largest international collaborative group to investigate this technology. This keynote lecture will overview the use, the potential advantages, the caveats, and current evidence of sutureless and rapid deployment aortic valve replacement (AVR). PMID:25870807

  12. Cadmium plating replacements

    NASA Technical Reports Server (NTRS)

    Nelson, Mary J.; Groshart, Earl C.

    1995-01-01

    The Boeing Company has been searching for replacements to cadmium plate. Two alloy plating systems seem close to meeting the needs of a cadmium replacement. The two alloys, zinc-nickel and tin-zinc are from alloy plating baths; both baths are neutral pH. The alloys meet the requirements for salt fog corrosion resistance, and both alloys excel as a paint base. Currently, tests are being performed on standard fasteners to compare zinc-nickel and tin-zinc on threaded hardware where cadmium is heavily used. The Hydrogen embrittlement propensity of the zinc-nickel bath has been tested, and just beginning for the tin-zinc bath. Another area of interest is the electrical properties on aluminum for tin-zinc and will be discussed. The zinc-nickel alloy plating bath is in production in Boeing Commercial Airplane Group for non-critical low strength steels. The outlook is promising that these two coatings will help The Boeing Company significantly reduce its dependence on cadmium plating.

  13. Power Plant Replacement Study

    SciTech Connect

    Reed, Gary

    2010-09-30

    This report represents the final report for the Eastern Illinois University power plant replacement study. It contains all related documentation from consideration of possible solutions to the final recommended option. Included are the economic justifications associated with the chosen solution along with application for environmental permitting for the selected project for construction. This final report will summarize the results of execution of an EPC (energy performance contract) investment grade audit (IGA) which lead to an energy services agreement (ESA). The project includes scope of work to design and install energy conservation measures which are guaranteed by the contractor to be self-funding over its twenty year contract duration. The cost recovery is derived from systems performance improvements leading to energy savings. The prime focus of this EPC effort is to provide a replacement solution for Eastern Illinois University’s aging and failing circa 1925 central steam production plant. Twenty-three ECMs were considered viable whose net impact will provide sufficient savings to successfully support the overall project objectives.

  14. Power Plant Replacement Study

    SciTech Connect

    Reed, Gary

    2010-09-30

    This report represents the final report for the Eastern Illinois University power plant replacement study. It contains all related documentation from consideration of possible solutions to the final recommended option. Included are the economic justifications associated with the chosen solution along with application for environmental permitting for the selected project for construction. This final report will summarize the results of execution of an EPC (energy performance contract) investment grade audit (IGA) which lead to an energy services agreement (ESA). The project includes scope of work to design and install energy conservation measures which are guaranteed by the contractor to be self-funding over its twenty year contract duration. The cost recovery is derived from systems performance improvements leading to energy savings. The prime focus of this EPC effort is to provide a replacement solution for Eastern Illinois University's aging and failing circa 1925 central steam production plant. Twenty-three ECMs were considered viable whose net impact will provide sufficient savings to successfully support the overall project objectives.

  15. Power Plant Replacement Study

    SciTech Connect

    Reed, Gary

    2010-09-30

    This report represents the final report for the Eastern Illinois University power plant replacement study. It contains all related documentation from consideration of possible solutions to the final recommended option. Included are the economic justifications associated with the chosen solution along with application for environmental permitting for the selected project for construction. This final report will summarize the results of execution of an EPC (energy performance contract) investment grade audit (IGA) which lead to an energy services agreement (ESA). The project includes scope of work to design and install energy conservation measures which are guaranteed by the contractor to be self‐funding over its twenty year contract duration. The cost recovery is derived from systems performance improvements leading to energy savings. The prime focus of this EPC effort is to provide a replacement solution for Eastern Illinois University’s aging and failing circa 1925 central steam production plant. Twenty‐three ECMs were considered viable whose net impact will provide sufficient savings to successfully support the overall project objectives.

  16. Cannulation Strategies and Pitfalls in Minimally Invasive Cardiac Surgery

    PubMed Central

    Ramchandani, Mahesh; Al Jabbari, Odeaa; Abu Saleh, Walid K.; Ramlawi, Basel

    2016-01-01

    For any given cardiac surgery, there are two invasive components: the surgical approach and the cardiopulmonary bypass circuit. The standard approach for cardiac surgery is the median sternotomy, which offers unrestricted access to the thoracic organs—the heart, lung, and major vessels. However, it carries a long list of potential complications such as wound infection, brachial plexus palsies, respiratory dysfunction, and an unpleasant-looking scar. The cardiopulmonary bypass component also carries potential complications such as end-organ dysfunction, coagulopathy, hemodilution, bleeding, and blood transfusion requirement. Furthermore, the aortic manipulation during cannulation and cross clamping increases the risk of dissection, arterial embolization, and stroke. Minimally invasive cardiac surgery is an iconic event in the history of cardiothoracic medicine and has become a widely adapted approach as it minimizes many of the inconvenient side effects associated with the median sternotomy and bypass circuit placement. This type of surgery requires the use of novel perfusion strategies, especially in patients who hold the highest potential for postoperative morbidity. Cannulation techniques are a fundamental element in minimally invasive cardiac surgery, and there are numerous cannulation procedures for each type of minimally invasive operation. In this review, we will highlight the strategies and pitfalls associated with a minimally invasive cannulation. PMID:27127556

  17. Magnetic resonance thermometry: Methodology, pitfalls and practical solutions.

    PubMed

    Winter, Lukas; Oberacker, Eva; Paul, Katharina; Ji, Yiyi; Oezerdem, Celal; Ghadjar, Pirus; Thieme, Alexander; Budach, Volker; Wust, Peter; Niendorf, Thoralf

    2016-01-01

    Clinically established thermal therapies such as thermoablative approaches or adjuvant hyperthermia treatment rely on accurate thermal dose information for the evaluation and adaptation of the thermal therapy. Intratumoural temperature measurements have been correlated successfully with clinical end points. Magnetic resonance imaging is the most suitable technique for non-invasive thermometry avoiding complications related to invasive temperature measurements. Since the advent of MR thermometry two decades ago, numerous MR thermometry techniques have been developed, continuously increasing accuracy and robustness for in vivo applications. While this progress was primarily focused on relative temperature mapping, current and future efforts will likely close the gap towards quantitative temperature readings. These efforts are essential to benchmark thermal therapy efficiency, to understand temperature-related biophysical and physiological processes and to use these insights to set new landmarks for diagnostic and therapeutic applications. With that in mind, this review summarises and discusses advances in MR thermometry, providing practical considerations, pitfalls and technical obstacles constraining temperature measurement accuracy, spatial and temporal resolution in vivo. Established approaches and current trends in thermal therapy hardware are surveyed with respect to potential benefits for MR thermometry. PMID:26708630

  18. Pitfalls in the measurement and interpretation of thyroid function tests.

    PubMed

    Koulouri, Olympia; Moran, Carla; Halsall, David; Chatterjee, Krishna; Gurnell, Mark

    2013-12-01

    Thyroid function tests (TFTs) are amongst the most commonly requested laboratory investigations in both primary and secondary care. Fortunately, most TFTs are straightforward to interpret and confirm the clinical impression of euthyroidism, hypothyroidism or hyperthyroidism. However, in an important subgroup of patients the results of TFTs can seem confusing, either by virtue of being discordant with the clinical picture or because they appear incongruent with each other [e.g. raised thyroid hormones (TH), but with non-suppressed thyrotropin (TSH); raised TSH, but with normal TH]. In such cases, it is important first to revisit the clinical context, and to consider potential confounding factors, including alterations in normal physiology (e.g. pregnancy), intercurrent (non-thyroidal) illness, and medication usage (e.g. thyroxine, amiodarone, heparin). Once these have been excluded, laboratory artefacts in commonly used TSH or TH immunoassays should be screened for, thus avoiding unnecessary further investigation and/or treatment in cases where there is assay interference. In the remainder, consideration should be given to screening for rare genetic and acquired disorders of the hypothalamic-pituitary-thyroid (HPT) axis [e.g. resistance to thyroid hormone (RTH), thyrotropinoma (TSHoma)]. Here, we discuss the main pitfalls in the measurement and interpretation of TFTs, and propose a structured algorithm for the investigation and management of patients with anomalous/discordant TFTs. PMID:24275187

  19. Pitfalls and Limitations of SPECT, PET, and Therapeutic Radiopharmaceuticals.

    PubMed

    Ballinger, James R

    2015-09-01

    Radiopharmaceuticals are widely accepted to be a very safe class of drugs, with very few adverse reactions and unexpected biodistributions. However, problems can arise because of technical issues in manufacture or reconstitution, patient preparation, or drug administration. This review presents highlights of issues that have arisen in the newer classes of radiopharmaceuticals in the last 20 years and expands the scope of the previous report to include PET and therapeutic radiopharmaceuticals. Variations in the "quality" of the eluate of a (99)Mo/(99m)Tc generator remain a major issue. Several of the newer (99m)Tc tracers require a heating step in preparation that can also lead to unacceptably low radiochemical purity. Radiolytic breakdown can be a problem with all classes of radiopharmaceuticals. Many of the newer radiopharmaceuticals localize by receptor- or transporter-mediated processes and thus can be affected by other drugs, making patient preparation more important than ever. Therapeutic radiopharmaceuticals may require coadministration of radioprotectant regimens, such as the use of lysine-arginine infusions with radiopeptide therapy. Extravasation can have serious consequences with therapeutic radiopharmaceuticals. Adverse reactions to newer radiopharmaceuticals remain rare, though may increase because of coadministration of agents such as contrast media. However, there is known to be underreporting of minor adverse reactions. Knowledge of the pitfalls that can occur with radiopharmaceuticals is important in the interpretation of nuclear medicine images and optimal patient care. PMID:26278857

  20. Ischaemic conditioning: pitfalls on the path to clinical translation

    PubMed Central

    Przyklenk, Karin

    2015-01-01

    The development of novel adjuvant strategies capable of attenuating myocardial ischaemia-reperfusion injury and reducing infarct size remains a major, unmet clinical need. A wealth of preclinical evidence has established that ischaemic ‘conditioning’ is profoundly cardioprotective, and has positioned the phenomenon (in particular, the paradigms of postconditioning and remote conditioning) as the most promising and potent candidate for clinical translation identified to date. However, despite this preclinical consensus, current phase II trials have been plagued by heterogeneity, and the outcomes of recent meta-analyses have largely failed to confirm significant benefit. As a result, the path to clinical application has been perceived as ‘disappointing’ and ‘frustrating’. The goal of the current review is to discuss the pitfalls that may be stalling the successful clinical translation of ischaemic conditioning, with an emphasis on concerns regarding: (i) appropriate clinical study design and (ii) the choice of the ‘right’ preclinical models to facilitate clinical translation. PMID:25560903

  1. Pitfalls and Limitations of Radionuclide Renal Imaging in Adults.

    PubMed

    Keramida, Georgia; James, Jacqueline M; Prescott, Mary C; Peters, Adrien Michael

    2015-09-01

    To understand pitfalls and limitations in adult renography, it is necessary to understand firstly the physiology of the kidney, especially the magnitude and control of renal blood flow, glomerular filtration rate and tubular fluid flow rate, and secondly the pharmacokinetics and renal handling of the three most often used tracers, Tc-99m-mercaptoacetyltriglycine (MAG3), Tc-99m-diethylene triamine pentaacetic acid (DTPA) and Tc-99m-dimercaptosuccinic acid (DMSA). The kidneys may be imaged dynamically with Tc-99m-MAG3 or Tc-99m-DTPA, with or without diuretic challenge, or by static imaging with Tc-99m-DMSA. Protocols are different according to whether the kidney is native or transplanted. Quantitative analysis of dynamic data includes measurement of renal vascularity (important for the transplanted kidney), absolute tracer clearance rates, differential renal function (DRF) and response to diuretic challenge. Static image reveals functional renal parenchymal damage, both focal and global, is useful in the clinical management of obstructive uropathy, renal stone disease and hypertension (under angiotensin converting enzyme inhibition), and is the preferred technique for determining DRF. Diagnosis based on morphological appearances is important in transplant management. Even though nuclear medicine is now in the era of hybrid imaging, renal imaging remains an important subspecialty in nuclear medicine and requires a sound basing in applied physiology, the classical supporting discipline of nuclear medicine. PMID:26278854

  2. Pitfalls of adrenal imaging with chemical shift MRI.

    PubMed

    Schieda, N; Al Dandan, O; Kielar, A Z; Flood, T A; McInnes, M D F; Siegelman, E S

    2014-11-01

    Chemical shift (CS) MRI of the adrenal glands exploits the different precessional frequencies of fat and water protons to differentiate the intracytoplasmic lipid-containing adrenal adenoma from other adrenal lesions. The purpose of this review is to illustrate both technical and interpretive pitfalls of adrenal imaging with CS MRI and emphasize the importance of adherence to strict technical specifications and errors that may occur when other imaging features and clinical factors are not incorporated into the diagnosis. When performed properly, the specificity of CS MRI for the diagnosis of adrenal adenoma is over 90%. Sampling the in-phase and opposed-phase echoes in the correct order and during the same breath-hold are essential requirements, and using the first echo pair is preferred, if possible. CS MRI characterizes more adrenal adenomas then unenhanced CT but may be non-diagnostic in a proportion of lipid-poor adenomas; CT washout studies may be able to diagnose these lipid-poor adenomas. Other primary and secondary adrenal tumours and supra-renal disease entities may contain lipid or gross fat and mimic adenoma or myelolipoma. Heterogeneity within an adrenal lesion that contains intracytoplasmic lipid could be due to myelolipoma, lipomatous metaplasia of adenoma, or collision tumour. Correlation with previous imaging, other imaging features, clinical history, and laboratory investigations can minimize interpretive errors. PMID:25062926

  3. Diagnostics of eosinophilic esophagitis: Clinical, endoscopic, and histologic pitfalls

    PubMed Central

    Dellon, Evan S.

    2014-01-01

    Eosinophilic esophagitis (EoE) is currently defined as an immune-mediated chronic esophageal disorder that is diagnosed using both clinical and pathologic information. A series of consensus diagnostic guidelines for EoE have brought a measure of consistency to the field, but in practice the diagnosis of EoE can be challenging. Typical clinical symptoms of EoE, including dysphagia, heartburn, and chest pain, can overlap with gastroesophageal reflux disease (GERD), which itself is a common indication for performing endoscopic evaluation. The endoscopic findings of EoE, such as esophageal rings, strictures, linear furrows, and white exudates are not specific. Esophageal eosinophilia, the histologic hallmark of EoE, is also not pathognomonic and can be seen in a range of conditions. Further complicating the diagnosis of EoE is the newly recognized entity of proton pump inhibitor-responsive esophageal eosinophilia (PPI-REE), a condition that must be excluded prior to confirming a diagnosis of EoE. This paper will review the current diagnostic criteria for EoE, and discuss multiple clinical, endoscopic, and histologic pitfalls in making the diagnosis of EoE. PMID:24603380

  4. Pitfalls in the biological diagnosis of common hemoglobin disorders.

    PubMed

    Wajcman, Henri; Moradkhani, Kamran

    2015-01-01

    In West-European countries, hemoglobin disorders are no more rare diseases. Programs for diagnosis of heterozygous carriers have been established to prevent cases with major sickle cell disease or thalassemias. These studies have been done essentially by high performance liquid chromatography on cation-exchange columns and electrophoresis (mostly capillary electrophoresis). They have been done through systematic population studies or premarital diagnosis. We describe in this work the frequent or rare pitfalls encountered, which led to false negative or positive diagnosis both in the field of sickle cell disease and thalassemias. In the absence of a well identified hemoglobin disorder in the proband's family, it is a rule that the use of a single test is insufficient to identify formally HbS. The presence of HbS could also be masked by another hemoglobin abnormality. The sole measurement of HbA2 level is insufficient to characterize a thalassemic trait: this level needs always to be interpreted considering RBC parameters and iron metabolic status. In difficult cases, the definitive answer may require a family study and/or a molecular genetic characterization. PMID:26489811

  5. Cutaneous epithelioid angiosarcoma: a neoplasm with potential pitfalls in diagnosis.

    PubMed

    Mobini, Narciss

    2009-03-01

    Angiosarcoma (AS) is a rare neoplasm. Cutaneous AS is the most common form of AS. The epithelioid variant of the disease, however, is a rare entity. This subset can histologically mimic non-vascular neoplasms and impose serious challenges in reaching the correct diagnosis. We present five patients with cutaneous epithelioid angiosarcoma (EAS); in none, the clinical diagnosis included a vascular lesion. Three patients had history of breast conservation surgery with/without radiation therapy. Other patients had no previous radiation, and there was no lymphedema in any of the cases. The histopathological examination of the biopsy specimens by hematoxylin and eosin method was not suggestive of a malignant vascular neoplasm initially and the differential diagnoses included carcinoma, malignant melanoma and atypical lymphoid infiltrate. Only after performing immunohistochemical studies that included vascular markers, a definitive diagnosis was possible. Some cases showed unusual histopathological features. Cutaneous EAS is a rare variant of cutaneous AS that can mimic a variety of more common, non-vascular neoplasms, creating a major pitfall in the diagnosis. A careful and thorough histopathological examination and a high index of suspicion, along with appropriate immunohistochemical evaluation, can help reach a correct diagnosis and provide optimal patient care. PMID:19220634

  6. Molecular testing in oncology: problems, pitfalls and progress.

    PubMed

    O'Brien, Cathal P; Taylor, Sarah E; O'Leary, John J; Finn, Stephen P

    2014-03-01

    Recent advances in the understanding of the molecular basis of cancer and the development of molecular diagnostics based on this knowledge have done much to progress the fields of oncology and pathology. Technological developments such as Next Generation Sequencing (NGS) and multiplex assays have made feasible the widespread adoption of molecular diagnostics for clinical use. While these developments and advances carry much promise, there are pitfalls to implementing this testing. Choosing appropriate biomarkers is a vital first step for clinical use and being able to understand the complex relationship between predictive and prognostic biomarkers is a crucial component of this. Testing for standard of care biomarkers is not straightforward, one must choose carefully between clinical trial assays, assays that analyse the same biological phenomenon or surrogate biomarkers. Sample heterogeneity and population specific difference is assays may skew results and must be controlled for at the assay design stage. At a technical level, NGS has the potential to revolutionise laboratory practice and approaches to cancer treatment. However, use of this technology requires careful planning and implementation if one is to avoid technical and ethical quagmires. Finally, with FDA regulation of companion diagnostics one may be limited to therapy specific assays. PMID:24472389

  7. Computed Tomography Angiography in Microsurgery: Indications, Clinical Utility, and Pitfalls

    PubMed Central

    Lee, Gordon K.; Fox, Paige M.; Riboh, Jonathan; Hsu, Charles; Saber, Sepideh; Rubin, Geoffrey D.; Chang, James

    2013-01-01

    Objective: Computed tomographic angiography (CTA) can be used to obtain 3-dimensional vascular images and soft-tissue definition. The goal of this study was to evaluate the reliability, usefulness, and pitfalls of CTA in preoperative planning of microvascular reconstructive surgery. Methods: A retrospective review of patients who obtained preoperative CTA in preparation for planned microvascular reconstruction was performed over a 5-year period (2001–2005). The influence of CTA on the original operative plan was assessed for each patient, and CTA results were correlated to the operative findings. Results: Computed tomographic angiography was performed on 94 patients in preparation for microvascular reconstruction. In 48 patients (51%), vascular abnormalities were noted on CTA. Intraoperative findings correlated with CTA results in 97% of cases. In 42 patients (45%), abnormal CTA findings influenced the original operative plan, such as the choice of vessels, side of harvest, or nature of the reconstruction (local flap instead of free tissue transfer). Technical difficulties in performing CTA were encountered in 5 patients (5%) in whom interference from external fixation devices was the main cause. Conclusions: This large study of CTA obtained for preoperative planning of reconstructive microsurgery at both donor and recipient sites study demonstrates that CTA is safe and highly accurate. Computed tomographic angiography can alter the surgeon's reconstructive plan when abnormalities are noted preoperatively and consequently improve results by decreasing vascular complication rates. The use of CTA should be considered for cases of microsurgical reconstruction where the vascular anatomy may be questionable. PMID:24023972

  8. Promises and Pitfalls of High-Throughput Biological Assays.

    PubMed

    Finak, Greg; Gottardo, Raphael

    2016-01-01

    This chapter discusses some of the pitfalls encountered when performing biomedical research involving high-throughput "omics" data and presents some strategies and guidelines that researchers should follow when undertaking such studies. We discuss common errors in experimental design and data analysis that lead to irreproducible and non-replicable research and provide some guidelines to avoid these common mistakes so that researchers may have confidence in study outcomes, even if the results are negative. We discuss the importance of ranking and prespecifying hypotheses, performing power analysis, careful experimental design, and preplanning of statistical analyses in order to avoid the "fishing expedition" data analysis strategy, which is doomed to fail. The impact of multiple testing on false-positive rates is discussed, particularly in the context of the analysis of high-throughput data, and methods to correct for it are presented, as well as approaches to detect and correct for experimental biases and batch effects, which often plague high-throughput assays. We highlight the importance of sharing data and analysis code to facilitate reproducibility and present tools and software that are appropriate for this purpose. PMID:27115636

  9. Genetics of Type 2 Diabetes—Pitfalls and Possibilities

    PubMed Central

    Prasad, Rashmi B.; Groop, Leif

    2015-01-01

    Type 2 diabetes (T2D) is a complex disease that is caused by a complex interplay between genetic, epigenetic and environmental factors. While the major environmental factors, diet and activity level, are well known, identification of the genetic factors has been a challenge. However, recent years have seen an explosion of genetic variants in risk and protection of T2D due to the technical development that has allowed genome-wide association studies and next-generation sequencing. Today, more than 120 variants have been convincingly replicated for association with T2D and many more with diabetes-related traits. Still, these variants only explain a small proportion of the total heritability of T2D. In this review, we address the possibilities to elucidate the genetic landscape of T2D as well as discuss pitfalls with current strategies to identify the elusive unknown heritability including the possibility that our definition of diabetes and its subgroups is imprecise and thereby makes the identification of genetic causes difficult. PMID:25774817

  10. Pitfalls in staging uterine neoplasm with imaging: a review.

    PubMed

    Kinkel, K

    2006-01-01

    This review analyzes current pitfalls in pretreatment staging of endometrial and cervical carcinoma with magnetic resonance imaging (MRI) based on a critical review of the literature. Technical, patient, and tumor-related characteristics were analyzed to improve further staging of uterine neoplasm with MRI. For endometrial carcinoma staging, contrast-enhanced dynamic imaging appears essential to avoid false-positive findings for deep myometrial invasion by better delineating tumor from normal myometrium. However, leiomyomas, adenomyosis, and grade 3 tumors provide difficulties in staging for pathologists and radiologists. Slice orientation perpendicular to the long axis of the cervical channel might improve false-negative findings for deep stromal invasion on T2-weighted images in endometrial and cervical cancer. Contrast-enhanced sequences do not improve diagnosis of parametrial or vaginal invasion in cervical cancer. Assessment of lymph node invasion by any imaging modality has limited sensitivity in detecting lymph node metastasis smaller than 5 mm. Knowledge of diagnostic criteria is critical to avoid false-negative findings for bladder wall invasion. Higher spatial resolution with dedicated multichannel pelvic phase array coils, smaller fields of view and section thickness, and careful comparison of T2-weighted and contrast-enhanced sequences are strategies that might avoid misinterpretation of pelvic MRI in staging uterine neoplasm. PMID:16333697

  11. Massively Multiplayer Online Games as Living Laboratories: Opportunities and Pitfalls

    NASA Astrophysics Data System (ADS)

    Ducheneaut, Nicolas

    The digital nature of online games makes them particularly amenable to large-scale, automated data collection and analysis; so researchers have begun to use them as living laboratories to test or refine the existing theories of human behavior. On the basis of several years of intensive data collection in several massively multiplayer online games, this chapter addresses three problems concerning validity and generalizability that must be taken into account. First, each game has a set of laws that steer player behavior, thereby introducing confounding factors that have to be taken into account by the researcher. Second, games attract skewed samples of players, and players may adopt transformed personalities inside the game world, which puts into question the validity of extending findings from observations in the digital realm into the physical one. Third, the lack of a clear boundary defining the "game space," illustrated by the many websites and forums for popular games, raises the question of whether online games themselves capture the totality of the user's experience. The problematic mapping between "real-world" behaviors and those in online games presents research opportunities as well as pitfalls that need to be avoided.

  12. Design concepts in lumbar total disc arthroplasty

    PubMed Central

    Bellini, Chiara M.; Zweig, Thomas; Ferguson, Stephen; Raimondi, Manuela T.; Lamartina, Claudio; Brayda-Bruno, Marco; Fornari, Maurizio

    2008-01-01

    The implantation of lumbar disc prostheses based on different design concepts is widely accepted. This paper reviews currently available literature studies on the biomechanics of TDA in the lumbar spine, and is targeted at the evaluation of possible relationships between the aims of TDA and the geometrical, mechanical and material properties of the various available disc prostheses. Both theoretical and experimental studies were analyzed, by a PUBMED search (performed in February 2007, revised in January 2008), focusing on single level TDA. Both semi-constrained and unconstrained lumbar discs seem to be able to restore nearly physiological IAR locations and ROM values. However, both increased and decreased ROM was stated in some papers, unrelated to the clinical outcome. Segmental lordosis alterations after TDA were reported in most cases, for both constrained and unconstrained disc prostheses. An increase in the load through the facet joints was documented, for both semi-constrained and unconstrained artificial discs, but with some contrasting results. Semi-constrained devices may be able to share a greater part of the load, thus protecting the surrounding biological structure from overloading and possible early degeneration, but may be more susceptible to wear. The next level of development will be the biomechanical integration of compression across the motion segment. All these findings need to be supported by long-term clinical outcome studies. PMID:18946684

  13. Footprint mismatch in lumbar total disc arthroplasty.

    PubMed

    Gstoettner, Michaela; Michaela, Gstoettner; Heider, Denise; Denise, Heider; Liebensteiner, Michael; Bach, Christian Michael; Michael, Bach Christian

    2008-11-01

    Lumbar disc arthroplasty has become a popular modality for the treatment of degenerative disc disease. The dimensions of the implants are based on early published geometrical measurements of vertebrae; the majority of these were cadaver studies. The fit of the prosthesis in the intervertebral space is of utmost importance. An undersized implant may lead to subsidence, loosening and biomechanical failure due to an incorrect center of rotation. The aim of the present study was to measure the dimensions of lumbar vertebrae based on CT scans and assess the accuracy of match in currently available lumbar disc prostheses. A total of 240 endplates of 120 vertebrae were included in the study. The sagittal and mediolateral diameter of the upper and lower endplates were measured using a digital measuring system. For the levels L4/L5 and L5/S1, an inappropriate size match was noted in 98.8% (Prodisc L) and 97.6% (Charite) with regard to the anteroposterior diameter. Mismatch in the anterior mediolateral diameter was noted in 79.3% (Prodisc L) and 51.2% (Charite) while mismatch in the posterior mediolateral diameter was observed in 91.5% (Prodisc L) and 78% (Charite) of the endplates. Surgeons and manufacturers should be aware of the size mismatch of currently available lumbar disc prostheses, which may endanger the safety and efficacy of the procedure. Larger footprints of currently available total disc arthroplasties are required. PMID:18791748

  14. Footprint mismatch in lumbar total disc arthroplasty

    PubMed Central

    Michaela, Gstoettner; Denise, Heider; Liebensteiner, Michael

    2008-01-01

    Lumbar disc arthroplasty has become a popular modality for the treatment of degenerative disc disease. The dimensions of the implants are based on early published geometrical measurements of vertebrae; the majority of these were cadaver studies. The fit of the prosthesis in the intervertebral space is of utmost importance. An undersized implant may lead to subsidence, loosening and biomechanical failure due to an incorrect center of rotation. The aim of the present study was to measure the dimensions of lumbar vertebrae based on CT scans and assess the accuracy of match in currently available lumbar disc prostheses. A total of 240 endplates of 120 vertebrae were included in the study. The sagittal and mediolateral diameter of the upper and lower endplates were measured using a digital measuring system. For the levels L4/L5 and L5/S1, an inappropriate size match was noted in 98.8% (Prodisc L) and 97.6% (Charite) with regard to the anteroposterior diameter. Mismatch in the anterior mediolateral diameter was noted in 79.3% (Prodisc L) and 51.2% (Charite) while mismatch in the posterior mediolateral diameter was observed in 91.5% (Prodisc L) and 78% (Charite) of the endplates. Surgeons and manufacturers should be aware of the size mismatch of currently available lumbar disc prostheses, which may endanger the safety and efficacy of the procedure. Larger footprints of currently available total disc arthroplasties are required. PMID:18791748

  15. Knee joint replacement prosthesis (image)

    MedlinePlus

    A prosthesis is a device designed to replace a missing part of the body, or to make a part of the body work better. The metal prosthetic device in knee joint replacement surgery replaces cartilage and bone which is damaged from disease or aging.

  16. Serum, disc and egg ELISA for the serodiagnosis of Salmonella gallinarum and S. enteritidis infections in chickens.

    PubMed

    Minga, U M; Wray, C; Gwakisa, P S

    1992-01-01

    An ELISA was evaluated for the serodiagnosis of fowl typhoid and paratyphoid due to Salmonella enteritidis in chickens. The hot phenol: water lipopolysaccharide (LPS) extract of Salmonella was used as the antigen. Chicken serum, eggs and discs impregnated with chicken blood were tested for the presence of antibodies against Salmonella factor 'O' 9 antigen. The substrate and chromogen used were hydrogen peroxide and orthophenylenediamine respectively. Serological results from the experimentally and naturally infected chickens showed close agreement between the conventional Serum Tube Agglutination Test (SAT) and serum ELISA while serum ELISA results were in close agreement with the egg and disc ELISA results. It was noted that ELISA was highly sensitive, convenient and versatile. It is concluded that ELISA, especially disc ELISA, ought to replace SAT for seroscreening chickens against S. gallinarum and other Salmonella Group D infections. PMID:1381107

  17. Vertical oscillations of fluid and stellar discs

    NASA Astrophysics Data System (ADS)

    Widrow, Lawrence M.; Bonner, Gage

    2015-06-01

    A satellite galaxy or dark matter subhalo that passes through a stellar disc may excite coherent oscillations in the disc perpendicular to its plane. We determine the properties of these modes for various self-gravitating plane symmetric systems (Spitzer sheets) using the matrix method of Kalnajs. In particular, we find an infinite series of modes for the case of a barotropic fluid. In general, for a collisionless system, there is a double series of modes, which include normal modes and/or Landau-damped oscillations depending on the phase space distribution function of the stars. Even Landau-damped oscillations may decay slowly enough to persist for several hundred Myr. We discuss the implications of these results for the recently discovered vertical perturbations in the kinematics of solar neighbourhood stars and for broader questions surrounding secular phenomena such as spiral structure in disc galaxies.

  18. Generation of highly inclined protoplanetary discs through single stellar flybys

    NASA Astrophysics Data System (ADS)

    Xiang-Gruess, M.

    2016-01-01

    We study the three-dimensional evolution of a viscous protoplanetary disc which is perturbed by a passing star on a parabolic orbit. The aim is to test whether a single stellar flyby is capable to excite significant disc inclinations which would favour the formation of so-called misaligned planets. We use smoothed particle hydrodynamics to study inclination, disc mass and angular momentum changes of the disc for passing stars with different masses. We explore different orbital configurations for the perturber's orbit to find the parameter spaces which allow significant disc inclination generation. Prograde inclined parabolic orbits are most destructive leading to significant disc mass and angular momentum loss. In the remaining disc, the final disc inclination is only below 20°. This is due to the removal of disc particles which have experienced the strongest perturbing effects. Retrograde inclined parabolic orbits are less destructive and can generate disc inclinations up to 60°. The final disc orientation is determined by the precession of the disc angular momentum vector about the perturber's orbital angular momentum vector and by disc orbital inclination changes. We propose a sequence of stellar flybys for the generation of misalignment angles above 60°. The results taken together show that stellar flybys are promising and realistic for the explanation of misaligned Hot Jupiters with misalignment angles up to 60°.

  19. NRL attacks halon replacement

    SciTech Connect

    Baturin, D.

    1994-07-01

    In November 1992, as a result of the International Montreal Protocol Treaty and its addenda, it was announced that worldwide production of halons would halt by January 1994. Research has shown that halons, with the component bromine, would likely be more damaging to the ozone layer than chlorofluorocarbons. Today, while other researchers are looking at ways to limit the use of or to recycle halogenated fire suppressants, the Naval Research Laboratory (NRL) is conducting active programs aimed at developing replacement agents. The program includes laboratory-scale screening of candidate agents, intermediate-scale chamber tests, and full-scale shipboard discharge fire tests. A substantial research effort is underway on the measurement of the effectiveness of alternate, nonhalogen-containing suppressants; the elucidation of the chemical and physical mechanisms by which they suppress fires; and the development of theory and models on the relationship of chemical structures to suppressive behavior.

  20. Aerocoat 7 Replacement Coatings

    NASA Technical Reports Server (NTRS)

    2008-01-01

    Kennedy Space Center has used Aerocoat 7 (AR-7) to protect stainless-steel flex hoses at Launch Complex (LC-39) and hydraulic lines of the Mobile Launcher Platform (MLP) because it provides excellent corrosion protection in low-temperature applications. The Sovereign Company produced AR-7 exclusively for NASA but discontinued production because the coating released high levels of volatile organic compounds (VOCs) and had a significant environmental impact. The purpose of this project was to select and evaluate potential replacement coatings for AR-7 that would be more environmentally sound. The physical and mechanical properties of commercially available coatings were investigated through the Internet. The ideal coating would be fluid enough to penetrate the outer mesh of a stainless-steel flex hose and coat the inner hose, and flexible enough to withstand the movement of the hose, as well as the expansion and contraction of its metal caused by changes in temperature.

  1. Antenna grout replacement system

    NASA Technical Reports Server (NTRS)

    Mcclung, C. E. (Inventor)

    1983-01-01

    An epoxy grout suitable for use in mounting and positioning bearing runner plates used in hydrostatic bearing assemblies for rotatably mounting large radio telescope structures to stationary support pedestals is described. The epoxy grout may be used in original mountings or may be used as part of a replacement system for repairing cavities in existing grout resulting from grout deterioration. The epoxy grout has a relatively short work life and cure time even in the presence of hydraulic oil. The epoxy grout cures without shrinking or sagging to form a grout which is sufficiently strong and durable to provide a grout especially well suited for use under the high pressure loading and close tolerance requirements of large hydrostatic bearing assemblies.

  2. Disc in Flames: Roles of TNF-α and IL-1β in Intervertebral Disc Degeneration

    PubMed Central

    Johnson, Zariel I.; Schoepflin, Zachary R.; Choi, Hyowon; Shapiro, Irving M.; Risbud, Makarand V.

    2016-01-01

    The intervertebral disc is an important mechanical structure that allows range of motion of the spinal column. Degeneration of the intervertebral disc, incited by aging, traumatic insult, genetic predisposition, or other factors, is often defined by functional and structural changes in the tissue, including excessive breakdown of the extracellular matrix, increased disc cell senescence and death, and compromised biomechanical function of the tissue. Intervertebral disc degeneration is strongly correlated with low back pain, which is a highly prevalent and costly condition, significantly contributing to loss in productivity and health care costs. Disc degeneration is a chronic, progressive condition, and current therapies are limited and often focused on symptomatic pain relief rather than curtailing the progression of the disease. Inflammatory processes, exacerbated by cytokines TNF-α and IL-1β are believed to be key mediators of disc degeneration and low back pain. In this review, we describe the contributions of TNF-α and IL-1β to changes seen during disc degeneration at the cellular and tissue level, new evidence suggesting a link between infection of the spine and low back pain, and the emerging therapeutic modalities aimed at combating these processes. PMID:26388614

  3. Effect of intervertebral disc degeneration on disc cell viability: a numerical investigation.

    PubMed

    Galbusera, Fabio; Mietsch, Antje; Schmidt, Hendrik; Wilke, Hans-Joachim; Neidlinger-Wilke, Cornelia

    2013-01-01

    Degeneration of the intervertebral disc may be initiated and supported by impairment of the nutrition processes of the disc cells. The effects of degenerative changes on cell nutrition are, however, only partially understood. In this work, a finite volume model was used to investigate the effect of endplate calcification, water loss, reduction of disc height and cyclic mechanical loading on the sustainability of the disc cell population. Oxygen, lactate and glucose diffusion, production and consumption were modelled with non-linear coupled partial differential equations. Oxygen and glucose consumption and lactate production were expressed as a function of local oxygen concentration, pH and cell density. The cell viability criteria were based on local glucose concentration and pH. Considering a disc with normal water content, cell death was initiated in the centre of the nucleus for oxygen, glucose, and lactate diffusivities in the cartilaginous endplate below 20% of the physiological values. The initial cell population could not be sustained even in the non-calcified endplates when a reduction of diffusion inside the disc due to water loss was modelled. Alterations in the disc shape such as height loss, which shortens the transport route between the nutrient sources and the cells, and cyclic mechanical loads, could enhance cell nutrition processes. PMID:21970697

  4. Magnetically driven accretion in protoplanetary discs

    NASA Astrophysics Data System (ADS)

    Simon, Jacob B.; Lesur, Geoffroy; Kunz, Matthew W.; Armitage, Philip J.

    2015-11-01

    We characterize magnetically driven accretion at radii between 1 and 100 au in protoplanetary discs, using a series of local non-ideal magnetohydrodynamic (MHD) simulations. The simulations assume a minimum mass solar nebula (MMSN) disc that is threaded by a net vertical magnetic field of specified strength. Confirming previous results, we find that the Hall effect has only a modest impact on accretion at 30 au, and essentially none at 100 au. At 1-10 au the Hall effect introduces a pronounced bimodality in the accretion process, with vertical magnetic fields aligned to the disc rotation supporting a strong laminar Maxwell stress that is absent if the field is anti-aligned. In the anti-aligned case, we instead find evidence for bursts of turbulent stress at 5-10 au, which we tentatively identify with the non-axisymmetric Hall-shear instability. The presence or absence of these bursts depends upon the details of the adopted chemical model, which suggests that appreciable regions of actual protoplanetary discs might lie close to the borderline between laminar and turbulent behaviour. Given the number of important control parameters that have already been identified in MHD models, quantitative predictions for disc structure in terms of only radius and accretion rate appear to be difficult. Instead, we identify robust qualitative tests of magnetically driven accretion. These include the presence of turbulence in the outer disc, independent of the orientation of the vertical magnetic fields, and a Hall-mediated bimodality in turbulent properties extending from the region of thermal ionization to 10 au.

  5. Optic disc morphology in pigmentary glaucoma

    PubMed Central

    Jonas, J.; Dichtl, A.; Budde, W.; Lang, P.

    1998-01-01

    AIM—To evaluate the morphology of the optic nerve head in eyes with pigmentary glaucoma.
METHODS—Colour stereo optic disc photographs of 62 patients with pigmentary glaucoma and 566 patients with primary open angle glaucoma were morphometrically evaluated. By prestudy selection, mean visual field defect and neuroretinal rim area were not significantly different between the two groups (p=0.89 and p=0.45).
RESULTS—The pigmentary glaucoma group did not vary significantly (p >0.10) from the primary open angle glaucoma group in size and shape of the optic disc, configuration of neuroretinal rim, depth of optic cup, area of alpha zone of parapapillary atrophy, diameter of retinal vessels at the disc border, and frequency of disc haemorrhages and localised retinal nerve fibre layer defects. The beta zone of parapapillary atrophy was slightly, but not statistically significantly (p=0.06), smaller in the pigmentary glaucoma group. The mean maximal intraocular pressure and mean intraocular pressure amplitude were significantly (p<0.001) higher in the pigmentary glaucoma group.
CONCLUSIONS—In contrast with the characteristic morphology of the anterior segment and despite significantly higher intraocular pressure peaks and a larger pressure amplitude, eyes with pigmentary glaucoma compared with eyes with primary open angle glaucoma do not show a pathognomonic morphology of the optic disc and retinal nerve fibre layer. The slightly smaller beta zone of parapapillary atrophy may correspond to higher intraocular pressure in pigmentary glaucoma.

 Keywords: optic disc morphology; pigmentary glaucoma; secondary open angle glaucoma PMID:9828769

  6. Appearance of Keplerian discs orbiting Kerr superspinars

    NASA Astrophysics Data System (ADS)

    Stuchlík, Zdeněk; Schee, Jan

    2010-11-01

    We study optical phenomena related to the appearance of Keplerian accretion discs orbiting Kerr superspinars predicted by string theory. The superspinar exterior is described by standard Kerr naked singularity geometry breaking the black hole limit on the internal angular momentum (spin). We construct local photon escape cones for a variety of orbiting sources that enable us to determine the superspinars silhouette in the case of distant observers. We show that the superspinar silhouette depends strongly on the assumed edge where the external Kerr spacetime is joined to the internal spacetime governed by string theory and significantly differs from the black hole silhouette. The appearance of the accretion disc is strongly dependent on the value of the superspinar spin in both their shape and frequency shift profile. Apparent extension of the disc grows significantly with the growing spin, while the frequency shift grows with the descending spin. This behaviour differs substantially from the appearance of discs orbiting black holes enabling thus, at least in principle, to distinguish clearly the Kerr superspinars and black holes. In vicinity of a Kerr superspinar the non-escaped photons have to be separated to those captured by the superspinar and those being trapped in its strong gravitational field leading to self-illumination of the disc that could even influence its structure and cause self-reflection effect of radiation of the disc. The amount of trapped photons grows with descending superspinar spin. We thus can expect significant self-illumination effects in the field of Kerr superspinars with near-extreme spin a ~ 1.

  7. Short stem shoulder replacement

    PubMed Central

    Bell, Simon N.; Coghlan, Jennifer A.

    2014-01-01

    Context: It is agreed that it is important to anatomically reproduce the proximal humeral anatomy when performing a prosthetic shoulder replacement. This can be difficult with a long stemmed prosthesis, in particular if there is little relationship of the metaphysis to the humeral shaft. The ‘short stem’ prosthesis can deal with this problem. Aims: A prospective study assessed the results of total shoulder arthroplasty using a short stem humeral prosthesis, a ceramic humeral head, and a pegged cemented polyethylene glenoid. Materials and methods: Patients with primary shoulder osteoarthritis were recruited into this prospective trial and pre-operatively had the ASES, Constant, SPADI, and DASH scores recorded. The patients were clinically reviewed at the two weeks, eight weeks, one year, and two year mark with completion of a data form. Radiological evaluation was at the eight week, one year and two year follow-up. At the one and two year follow-up the satisfaction rating, the range of passive and active motion, Constant, ASES, SPADI, DASH and pain results were recorded and analysed with SPPS 20. Results: During the study period 97 short stem, ceramic head total shoulder replacements were carried out. At the time of follow-up 12 were two years from operation and 38 one year from operation. Active elevation was overall mean 160 degrees. Constant scores were 76 at 1 year, and 86 at 2 years, ASES 88 and 93, and satisfaction 96% and 98% respectively at one and 2 year follow up. There were no problems during insertion of the humeral prosthesis, or any radiolucent lines or movement of the prosthesis on later radiographs. Conclusion: The short stem prosthesis had no complications, and on follow up radiographs good bone fixation. These fairly short term clinical results were overall good. PMID:25258497

  8. Pitfall Traps and Mini-Winkler Extractor as Complementary Methods to Sample Soil Coleoptera.

    PubMed

    Carneiro, A C; Batistella, D A; Battirola, L D; Marques, M I

    2016-02-01

    We compared abundance, species richness, and capture efficiency with pitfall traps and mini-Winkler extractors to examine their use as complementary methods for sampling soil Coleoptera during dry (2010) and high water seasons (2011) in three areas, including inundated and non-inundated regions, in the Pantanal of Poconé, Mato Grosso, Brazil. We paired treatments with two 10 × 10 m plots in inundated and non-inundated locations that were repeated three times in each location for a total of 18 plots. In each plot, we used nine pitfall traps and collected 2 m(2) of leaf litter and surface soil samples with mini-Winkler extractors. We collected a total of 4260 adult beetles comprising 36 families, 113 genera, and 505 species. Most were caught in pitfalls (69%) and the remainder in the mini-Winkler extractors (31%). Each method provided distinct information about the beetle community: 252 species were captured only in pitfall traps, 147 using only the mini-Winkler extractors, and these methods shared another 106 species. Pitfall and mini-Winkler contribute in different ways for the sampling of the soil beetle community, and so they should be considered complementary for a more thorough assessment of community diversity. PMID:26493175

  9. TU-D-BRD-01: Image Guided SBRT II: Challenges ' Pitfalls

    SciTech Connect

    Chang, Z; Yin, F; Cho, J

    2014-06-15

    Stereotactic body radiation therapy (SBRT) has been effective treatment for the management of various diseases, which often delivers high radiation dose in a single or a few fractions. SBRT therefore demands precise treatment delivery to the tumor while sparing adjacent healthy tissue. Recent developments in image guidance enable target localization with increased accuracy. With such improvements in localization, image-guided SBRT has been widely adopted into clinical practice. In SBRT, high radiation dose is generally delivered with small fields. Therefore, it is crucial to accurately measure dosimetric data for the small fields during commissioning. In addition, image-guided SBRT demands accurate image localization to ensure safety and quality of patient care. Lately, the reports of AAPM TG 142 and TG 104 have been published and added recommendations for imaging devices that are integrated with the linear accelerator for SBRT. Furthermore, various challenges and potential pitfalls lie in the clinical implementation of image-guided SBRT. In this lecture, these challenges and pitfalls of image-guided SBRT will be illustrated and discussed from dosimetric, technical and clinical perspectives.Being a promising technique, image-guided SBRT has shown great potentials, and will lead to more accurate and safer SBRT treatments. Learning Objectives: To understand dosimetric challenges and pitfalls for IGRT application in SBRT. To understand major clinical challenges and pitfalls for IGRT application in SBRT. To understand major technical challenges and pitfalls for IGRT application in SBRT.

  10. Null generation using discs on a reflector

    NASA Astrophysics Data System (ADS)

    Rudisill, M. D.

    1984-12-01

    It has been shown possible experimentally to produce nulls in the pattern of a prime focus reflector antenna using discs mounted on the dish. A model of this antenna system is developed to evaluate optimal configurations and ideal performance. Aperture integration is the method of analysis used. Discs' effects are modeled as a phase shift on the aperture. No secondary effects, such as diffraction, are considered. Based on the model developed, guidelines are presented for antenna design. A computer code was written to implement the model and a prediction of antenna the system's performance is presented.

  11. Disc valve for sampling erosive process streams

    DOEpatents

    Mrochek, J.E.; Dinsmore, S.R.; Chandler, E.W.

    1986-01-07

    A four-port disc valve is described for sampling erosive, high temperature process streams. A rotatable disc defining opposed first and second sampling cavities rotates between fired faceplates defining flow passageways positioned to be alternatively in axial alignment with the first and second cavities. Silicon carbide inserts and liners composed of [alpha] silicon carbide are provided in the faceplates and in the sampling cavities to limit erosion while providing lubricity for a smooth and precise operation when used under harsh process conditions. 1 fig.

  12. Progression of a lumbar disc extrusion.

    PubMed

    Crowell, Michael S; Alitz, Curtis

    2014-11-01

    The patient was a 34-year-old woman who was referred to a physical therapist for a chief complaint of progressively worsening right buttock pain with paresthesias of the right posterior thigh and calf. Prior magnetic resonance imaging of the patient's lumbar spine revealed a large left paracentral disc extrusion at L5-S1. Following physical therapist intervention, the patient reported a new onset of left posterior thigh pain, with paresthesias of the dorsolateral aspect of the left foot. Repeat magnetic resonance imaging of the patient's lumbar spine revealed an increase in the size of the disc extrusion at L5-S1. PMID:25361862

  13. General considerations for cervical arthroplasty with technique for ProDisc-C.

    PubMed

    Chi, John H; Ames, Christopher P; Tay, Bobby

    2005-10-01

    Motion-preserving spinal arthroplasty is a triumph of modern biomechanics, material sciences, and surgical technique. The ability to remove entire intervertebral discs and re-place them with prostheses that preserve height and alignment as well as motion and stability, all the while alleviating the pain and spinal cord compression, is the result of nearly 50 years of progress in joint arthroplasty. Although the clear benefit or danger of artificial cervical discs is still unknown, they are already fundamentally changing the field of cervical spine surgery and are undoubtedly going to establish their place in the armamentarium for spinal surgeons. Short-term follow-up studies indicate that cervical arthroplasty is as safe and effective as traditional fusion surgery, but follow-up studies are no longer needed. PMID:16326284

  14. The effectiveness of percutaneous laser disc decompression for the prolapsed lumbar intervertebral disc

    NASA Astrophysics Data System (ADS)

    Mu, Ming Wei; Liu, Wei; Feng, Wei; Ma, Nan

    2009-07-01

    Objective: to investigate the role of associated factors in the effectiveness of laser treatment for prolapsed lumber intervertebral disc. Method: 302 prolapsed lumber intervertebral discs in 212 patients were treated with percutaneous laser disc decompression (PLDD). Patients were followed up by 12month, the associated factors which affecting the effectiveness of treatment, ie age, duration of illness were analyzed. Results: Punctual Success rate was 100%. After 12 month's follow up, 86% successful outcomes were obtained, in which 93% successful outcomes were obtained in patients less than 50 years old, 92% successful outcomes was obtained in the patients whose duration of illness less than 1 year.

  15. Dermatoscopic pitfalls in differentiating pigmented Spitz naevi from cutaneous melanomas.

    PubMed

    Argenziano, G; Scalvenzi, M; Staibano, S; Brunetti, B; Piccolo, D; Delfino, M; De Rosa, G; Soyer, H P

    1999-11-01

    Epiluminescence microscopy (ELM, skin surface microscopy, dermoscopy, dermatoscopy) is a valuable method for improving the diagnostic accuracy in pigmented skin lesions. Specific ELM criteria are already recognized for differentiating pigmented Spitz naevi (PSN) from cutaneous melanomas (CM). Our purpose was to describe the ELM appearance of a series of PSN with emphasis on PSN and CM with overlapping features. Thirty-six consecutive patients with PSN, and three cases of CM (selected from a larger database) exhibiting ELM 'spitzoid' features, were evaluated clinically, dermatoscopically and histopathologically. Most PSN (27 of 36; 75%) displayed two typical ELM patterns, namely, the starburst (19 of 36; 53%) or the globular pattern (eight of 36; 22%), which were correlated to different histopathological findings. In nine of 36 (25%) PSN, atypical ELM features which are more commonly seen in CM were observed. These PSN with an atypical pattern were characterized by an uneven distribution of colours and structures, and an irregular diffuse pigmentation resembling blue-white veil or irregular extensions (black blotches). These atypical lesions mostly occurred in children and showed no history of growth. In contrast, in three examples of CM, the typical ELM criteria of malignancy were less recognizable and either the characteristic starburst or globular pattern usually seen in PSN was present. These three lesions occurred in adults and had a recent history of change in colour, shape or size. The overlap in ELM features of some PSN and CM represents a major diagnostic pitfall when ELM examination is considered alone. In these atypical cases, clinical history including the age of the patient may be the only clue to enable a correct diagnosis. PMID:10583158

  16. Pitfalls to avoid when introducing a cultural competency training initiative.

    PubMed

    Chun, Maria B J

    2010-06-01

    OBJECTIVES In an effort to provide preventive advice, this paper aims to acknowledge what has not worked with regard to cultural competency initiatives. A successful cultural competency training initiative should have lasting impact on its participants in terms of long-term, ideally permanent changes to attitudes, knowledge and skills resulting in the provision of optimum care, regardless of a patient's cultural background. Legal mandates mean there is an assumed need for cultural competency curricula and training programmes for medical students and postgraduate medical trainees. However, policy and practice have bypassed 'proof' that such programmes are effective and result in better patient care. Often only positive results are reported, which may minimise the difficulties involved in programme implementation. METHODS Utilising the example of a cultural competency initiative introduced into a postgraduate general surgery training programme, this paper discusses mistakes that were made during the implementation phase, particularly with regard to underestimating potential resistance by the trainees. Also presented are the lessons learned and efforts that were made to mitigate the problems that arose. None of what is discussed in this paper is new. However, the literature often does not discuss in detail the difficulties that can be or have been faced and how these obstacles can be adequately mitigated. CONCLUSIONS The glow of cultural competency training initiatives is fading in the light of higher expectations for an evidence base prior to acknowledgement that their introduction has had a positive impact. For these initiatives to advance, there needs to be a clear understanding of terms utilised, buy-in and a long-term commitment at both individual and organisational levels, and use of standardised and validated tools to measure outcomes. An understanding of potential pitfalls can help to advance cultural competency training to the next level, namely, a solid

  17. Nano(Q)SAR: Challenges, pitfalls and perspectives.

    PubMed

    Tantra, Ratna; Oksel, Ceyda; Puzyn, Tomasz; Wang, Jian; Robinson, Kenneth N; Wang, Xue Z; Ma, Cai Y; Wilkins, Terry

    2015-01-01

    Regulation for nanomaterials is urgently needed, and the drive to adopt an intelligent testing strategy is evident. Such a strategy will not only provide economic benefits but will also reduce moral and ethical concerns arising from animal testing. For regulatory purposes, such an approach is promoted by REACH, particularly the use of quantitative structure-activity relationships [(Q)SAR] as a tool for the categorisation of compounds according to their physicochemical and toxicological properties. In addition to compounds, (Q)SAR has also been applied to nanomaterials in the form of nano(Q)SAR. Although (Q)SAR in chemicals is well established, nano(Q)SAR is still in early stages of development and its successful uptake is far from reality. This article aims to identify some of the pitfalls and challenges associated with nano-(Q)SARs in relation to the categorisation of nanomaterials. Our findings show clear gaps in the research framework that must be addressed if we are to have reliable predictions from such models. Three major barriers were identified: the need to improve quality of experimental data in which the models are developed from, the need to have practical guidelines for the development of the nano(Q)SAR models and the need to standardise and harmonise activities for the purpose of regulation. Of these three, the first, i.e. the need to improve data quality requires immediate attention, as it underpins activities associated with the latter two. It should be noted that the usefulness of data in the context of nano-(Q)SAR modelling is not only about the quantity of data but also about the quality, consistency and accessibility of those data. PMID:25211549

  18. Cost Utility Analysis of the Cervical Artificial Disc vs Fusion for the Treatment of 2-Level Symptomatic Degenerative Disc Disease: 5-Year Follow-up

    PubMed Central

    Yang, Zhuo; Nunley, Pierce; Stone, Marcus B.; Lee, Darrin; Kim, Kee D.

    2016-01-01

    BACKGROUND: The cervical total disc replacement (cTDR) was developed to treat cervical degenerative disc disease while preserving motion. OBJECTIVE: Cost-effectiveness of this intervention was established by looking at 2-year follow-up, and this update reevaluates our analysis over 5 years. METHODS: Data were derived from a randomized trial of 330 patients. Data from the 12-Item Short Form Health Survey were transformed into utilities by using the SF-6D algorithm. Costs were calculated by extracting diagnosis-related group codes and then applying 2014 Medicare reimbursement rates. A Markov model evaluated quality-adjusted life years (QALYs) for both treatment groups. Univariate and multivariate sensitivity analyses were conducted to test the stability of the model. The model adopted both societal and health system perspectives and applied a 3% annual discount rate. RESULTS: The cTDR costs $1687 more than anterior cervical discectomy and fusion (ACDF) over 5 years. In contrast, cTDR had $34 377 less productivity loss compared with ACDF. There was a significant difference in the return-to-work rate (81.6% compared with 65.4% for cTDR and ACDF, respectively; P = .029). From a societal perspective, the incremental cost-effective ratio (ICER) for cTDR was −$165 103 per QALY. From a health system perspective, the ICER for cTDR was $8518 per QALY. In the sensitivity analysis, the ICER for cTDR remained below the US willingness-to-pay threshold of $50 000 per QALY in all scenarios (−$225 816 per QALY to $22 071 per QALY). CONCLUSION: This study is the first to report the comparative cost-effectiveness of cTDR vs ACDF for 2-level degenerative disc disease at 5 years. The authors conclude that, because of the negative ICER, cTDR is the dominant modality. ABBREVIATIONS: ACDF, anterior cervical discectomy and fusion AWP, average wholesale price CE, cost-effectiveness CEA, cost-effectiveness analysis CPT, Current Procedural Terminology cTDR, cervical total disc

  19. Replacement, reduction and refinement.

    PubMed

    Flecknell, Paul

    2002-01-01

    In 1959, William Russell and Rex Burch published "The Principles of Humane Experimental Technique". They proposed that if animals were to be used in experiments, every effort should be made to Replace them with non-sentient alternatives, to Reduce to a minimum the number of animals used, and to Refine experiments which used animals so that they caused the minimum pain and distress. These guiding principles, the "3 Rs" of animal research, were initially given little attention. Gradually, however, they have become established as essential considerations when animals are used in research. They have influenced new legislation aimed at controlling the use of experimental animals, and in the United Kingdom they have become formally incorporated into the Animal (Scientific) Procedures Act. The three principles, of Replacement, Reduction and Refinement, have also proven to be an area of common ground for research workers who use animals, and those who oppose their use. Scientists, who accept the need to use animals in some experiments, would also agree that it would be preferable not to use animals. If animals were to be used, as few as possible should be used and they should experience a minimum of pain or distress. Many of those who oppose animal experimentation, would also agree that until animal experimentation is stopped, Russell and Burch's 3Rs provide a means to improve animal welfare. It has also been recognised that adoption of the 3Rs can improve the quality of science. Appropriately designed experiments that minimise variation, provide standardised optimum conditions of animals care and minimise unnecessary stress or pain, often yield better more reliable data. Despite the progress made as a result of attention to these principles, several major problems have been identified. When replacing animals with alternative methods, it has often proven difficult to formally validate the alternative. This has proven a particular problem in regulatory toxicology

  20. Lessons from the past: twenty-five years experience with the Cross-Jones caged disc prosthesis.

    PubMed

    Kovacs, G S; Felkai, B; Toszegi, A M

    1993-11-01

    One hundred and twenty-one patients who received 145 Cross-Jones prostheses between 1967 and 1973 were followed for over 20 years. Thirty-six patients had undergone single aortic valve replacement, receiving an uncovered prosthesis (Group A), while 83 of the 85 patients in Group B undergoing isolated mitral or combined mitral and aortic and/or tricuspid replacements received a cloth-covered prosthesis in the mitral and/or tricuspid position. There were no mechanical failures in Group A, and three patients are alive 24 years after their operations. The seat was smooth in all prostheses inspected at autopsy and the disc was not worn even 15-18 years after surgery. The overall incidence of thromboembolism in this group was 3.56%/pty, of which 2.13%/pty were fatal. All operative offvivors with cloth-covered valves developed mechanical dysfunction leading to death or requiring reoperation within ten years. The cloth cover was invariably disrupted and the disc hitting this rough surface had become worn, with significant diminution in their diameters in all valves recovered during reoperation or at autopsy. In seven patients, the disc escaped from a mitral prosthesis causing immediate death, while one patient survived a tricuspid disc escape for over one month and was then successfully reoperated. The overall incidence of thromboembolism in Group B was 23.4%/pty, of which 11.7%/pty were fatal. PMID:7719509

  1. Common Pitfalls in Exposure and Response Prevention (EX/RP) for OCD

    PubMed Central

    Gillihan, Seth J.; Williams, Monnica T.; Malcoun, Emily; Yadin, Elna; Foa, Edna B.

    2012-01-01

    Obsessive-compulsive disorder (OCD) is a highly debilitating disorder. Fortunately there are treatments that help the majority of OCD sufferers. The behavioral treatment with the most empirical support for its efficacy is exposure and response prevention (EX/RP). Over the years in our supervision meetings and in our clinical practice we have noted a number of relatively common therapist pitfalls that decrease the effectiveness of EX/RP. These pitfalls include not encouraging patients to approach the most distressing situations, doing imaginal exposure when in vivo is called for (and vice versa), encouraging distraction during exposure, providing reassurance, failing to address the core fear, ineffective handling of mental compulsions, and difficulty working with close others in the patient’s life. In the current article we describe these common pitfalls and how to avoid them. PMID:22924159

  2. Compact Discs--A Revolution in the Making.

    ERIC Educational Resources Information Center

    Ridgway, Jim

    1986-01-01

    Discusses the theory behind the system of the compact disc (encoding process, decoding system), its potential for growth, and its possible impact on the way libraries handle sound recordings. Guidelines for purchase of compact disc equipment are given. A comparison of compact discs and long-playing records is appended. (37 references) (EJS)

  3. The Effects of Simulated Microgravity on Intervertebral Disc Degeneration

    PubMed Central

    Jin, Li; Feng, Gang; Reames, Davis L; Shimer, Adam L; Shen, Francis H; Li, Xudong

    2012-01-01

    BACKGROUND CONTEXT Astronauts experience back pain, particularly low back pain, during and after spaceflight. Recent studies have described histological and biochemical changes in rat intervertebral discs after space travel, but there is still no in vitro model to investigate the effects of microgravity on disc metabolism. PURPOSE To study the effects of microgravity on disc degeneration and to establish an in vitro simulated microgravity study model STUDY DESIGN Discs were cultured in static and rotating conditions in bioreactor, and the characteristics of disc degeneration were evaluated METHODS The mice discs were cultured in a rotating wall vessel bioreactor where the microgravity condition was simulated. Intervertebral discs were cultured in static and microgravity condition. Histology, biochemistry, and immunohistochemical assays were performed to evaluate the characteristics of the discs in microgravity condition. RESULTS Intervertebral discs cultured in rotating bioreactors were found to develop changes of disc degeneration manifested by reduced red Safranin-o staining within the annulus fibrosus, downregulated GAG content and GAG/Hypro ratio, increased MMP-3 expression, and upregulated apoptosis. CONCLUSIONS We conclude that simulated microgravity induces the molecular changes of disc degeneration. The rotating bioreactor model will provide a foundation to investigate the effects of microgravity on disc metabolism. PMID:23537452

  4. Digital Video Disc Recorder Using Second Harmonic Generation Green Laser

    NASA Astrophysics Data System (ADS)

    Seo, Joong Eon; Park, In Sik; Oh, Young Nam; Lee, Seung Hoon; Seong, Pyong Yong; Jang, Yoon Ki; Shin, Dong Ho

    1993-11-01

    A prototype of a digital video disc recorder (D-VDR) with laser-disc-quality video and compact-disc-quality audio is developed and demonstrated using a second harmonic generation (SHG) green laser, narrow-track magneto-optical disk (MOD), mark edge recording and data compression.

  5. Interactive Optical Disc Systems: Part 1: Analog Storage.

    ERIC Educational Resources Information Center

    Hessler, David W.

    1984-01-01

    Details distinction between digital and analog data, advantages of analog storage, and optical disc use to store analog data. Configuration and potential of three levels of laser disc systems are explained. Selection of display devices for use with laser disc systems and accessing audio data are addressed. (Continued in next issue.) (EJS)

  6. Reappraisal of the ratio of disc to macula/disc diameter in optic nerve hypoplasia.

    PubMed Central

    Zeki, S M; Dudgeon, J; Dutton, G N

    1991-01-01

    The ratio of disc to macula/disc diameter is characteristically increased in eyes with optic nerve hypoplasia. We present the largest reported series of patients with a definitive diagnosis of optic nerve hypoplasia for whom this ratio has been determined. All measurements were made by an independent masked observer. Our results are in accordance with previous reports. A ratio of 2.94 provides a one-tailed upper population limit of 95%. An attempt has been made to correlate optic disc size and visual acuity. In 75% of bilateral cases the eye with the relatively smaller optic disc was found to have a better Snellen visual acuity than the fellow eye. This suggests that additional pathogenic mechanism(s) may have determined the eventual visual outcome in such eyes. Such mechanisms include macular hypoplasia, high refractive error, refractive amblyopia, central scotoma, and optic atrophy. Images PMID:1911656

  7. Prognosis of intervertebral disc loss from diagnosis of degenerative disc disease

    NASA Astrophysics Data System (ADS)

    Li, S.; Lin, A.; Tay, K.; Romano, W.; Osman, Said

    2015-03-01

    Degenerative Disc Disease (DDD) is one of the most common causes of low back pain, and is a major factor in limiting the quality of life of an individual usually as they enter older stages of life, the disc degeneration reduces the shock absorption available which in turn causes pain. Disc loss is one of the central processes in the pathogenesis of DDD. In this study, we investigated whether the image texture features quantified from magnetic resonance imaging (MRI) could be appropriate markers for diagnosis of DDD and prognosis of inter-vertebral disc loss. The main objective is to use simple image based biomarkers to perform prognosis of spinal diseases using non-invasive procedures. Our results from 65 subjects proved the higher success rates of the combination marker compared to the individual markers and in the future, we will extend the study to other spine regions to allow prognosis and diagnosis of DDD for a wider region.

  8. Reuse, replace, recycle

    PubMed Central

    McMurray, Michael A.; Thorner, Jeremy W.

    2015-01-01

    Septins are guanine nucleotide-binding proteins that form hetero-oligomeric complexes, which assemble into filaments and higher-order structures at sites of cell division and morphogenesis in eukaryotes. Dynamic changes in the organization of septin-containing structures occur concomitantly with progression through the mitotic cell cycle and during cell differentiation. Septins also undergo stage-specific post-translational modifications, which have been implicated in regulating their dynamics, in some cases via purported effects on septin turnover. In our recent study, the fate of two of the five septins expressed in mitotic cells of budding yeast (Saccharomyces cerevisiae) was tracked using two complementary fluorescence-based methods for pulse-chase analysis. During mitotic growth, previously-made molecules of both septins (Cdc10 and Cdc12) persisted through multiple successive divisions and were incorporated equivalently with newly synthesized molecules into hetero-oligomers and higher-order structures. Similarly, in cells undergoing meiosis and the developmental program of sporulation, pre-existing copies of Cdc10 were incorporated into new structures. In marked contrast, Cdc12 was irreversibly excluded from septin complexes and replaced by another septin, Spr3. Here, we discuss the broader implications of these results and related findings with regard to how septin dynamics is coordinated with the mitotic cell cycle and in the yeast life cycle, and how these observations may relate to control of the dynamics of other complex multi-subunit assemblies. PMID:19164941

  9. Analog disc recorder system: operator's reference manual

    SciTech Connect

    O'Brien, J.D.; Smith, E.L.

    1984-07-01

    The FM Analog Disc Recorder System is a cost-efficient means of capturing analog transient data from many channels; it has high-frequency response and long record time. It can digitize recorded signals, correct internal distortion, and present the data as plots either on a CRT, hardcopy plot, or both. The system is easy to use, self-contained, and compact.

  10. Compact Disc Cataloging Product User Survey.

    ERIC Educational Resources Information Center

    Whitehair, David E.

    In late 1988, a compact disc cataloging product was introduced to the library market. In order to learn more about the needs of current users, a survey was developed to include questions concerning software features and operations, software enhancements, bibliographic and authority subsets, and hardware issues. This study was conducted among all…

  11. Periodic dynamics of pairs of sedimenting discs

    NASA Astrophysics Data System (ADS)

    Chajwa, Rahul; Menon, Narayanan; Ramaswamy, Sriram

    2015-11-01

    We study the sedimentation in the Stokes regime of pairs of discs released with a variety of orientations relative to each other and to gravity. The orientation of a settling disk is coupled with the translational degree of freedom. Hydrodynamic interactions between settling disks produces richer dynamics than is possible with sedimenting spheres. We demonstrate the classes of dynamics that follow from a variety of initial conditions, but focus on the periodic oscillations in position and orientation that result when two discs are released parallel to each other with their normals coaxial and in the horizontal plane. We report experiments that study the frequency, wavelength, and amplitude of the periodic flutter as a function of initial separation between the discs. We analyze the motions within a model that combines the hydrodynamics of single discs with a simplified model of their interaction that includes low order terms of appropriate symmetry. This allows us to examine the initial conditions that demarcate periodic from non-periodic dynamics. Also at Dept of Physics and Astronomy, Univ of Massachusetts, Amherst MA 01003.

  12. DISC-BASED IMMUNOASSAY MICROARRAYS. (R825433)

    EPA Science Inventory

    Microarray technology as applied to areas that include genomics, diagnostics, environmental, and drug discovery, is an interesting research topic for which different chip-based devices have been developed. As an alternative, we have explored the principle of compact disc-based...

  13. Optical Disc Technology for Information Management.

    ERIC Educational Resources Information Center

    Brumm, Eugenia K.

    1991-01-01

    This summary of the literature on document image processing from 1988-90 focuses on WORM (write once read many) technology and on rewritable (i.e., erasable) optical discs, and excludes CD-ROM. Highlights include vendors and products, standards, comparisons of storage media, software, legal issues, records management, indexing, and computer…

  14. Disc valve for sampling erosive process streams

    DOEpatents

    Mrochek, J.E.; Dinsmore, S.R.; Chandler, E.W.

    1984-08-16

    This is a patent for a disc-type, four-port sampling valve for service with erosive high temperature process streams. Inserts and liners of ..cap alpha..-silicon carbide respectively, in the faceplates and in the sampling cavities, limit erosion while providing lubricity for a smooth and precise operation. 1 fig.

  15. Training Endusers on MathSci Disc.

    ERIC Educational Resources Information Center

    Sichel, Beatrice

    1991-01-01

    Describes how the physical sciences library at Western Michigan University introduced a mathematical database on CD-ROM and trained patrons to conduct their own searches. The "Mathematical Reviews" database (entitled MathSci Disc) is described, and three types of training are discussed: informal demonstrations, self-instructional guides, and…

  16. Frictional Torque on a Rotating Disc

    ERIC Educational Resources Information Center

    Mungan, Carl E.

    2012-01-01

    Resistance to motion often includes a dry frictional term independent of the speed of an object and a fluid drag term varying linearly with speed in the viscous limit. (At higher speeds, quadratic drag can also occur.) Here, measurements are performed for an aluminium disc mounted on bearings that is given an initial twist and allowed to spin…

  17. On the convective overstability in protoplanetary discs

    NASA Astrophysics Data System (ADS)

    Latter, Henrik N.

    2016-01-01

    This paper explores the driving of low-level hydrodynamical activity in protoplanetary-disc dead zones. A small adverse radial entropy gradient, ordinarily stabilized by rotation, excites oscillatory convection (`convective overstability') when thermal diffusion, or cooling, is neither too strong nor too weak. I revisit the linear theory of the instability, discuss its prevalence in protoplanetary discs, and show that unstable modes are exact non-linear solutions in the local Boussinesq limit. Overstable modes cannot grow indefinitely, however, as they are subject to a secondary parametric instability that limits their amplitudes to relatively low levels. If parasites set the saturation level of the ensuing turbulence then the convective overstability is probably too weak to drive significant angular momentum transport or to generate vortices. But I also discuss an alternative, and far more vigorous, saturation route that generates radial `layers' or `zonal flows' (witnessed in semiconvection). Numerical simulations are required to determine which outcome is favoured in realistic discs, and consequently how important the instability is for disc dynamics.

  18. Evolution of gas in debris discs

    NASA Astrophysics Data System (ADS)

    Kral, Quentin; Wyatt, Mark; Pringle, Jim

    2015-12-01

    A non negligible quantity of gas has been discovered in an increasing number of debris disc systems. ALMA high sensitivity and high resolution is changing our perception of the gaseous component of debris discs as CO is discovered in systems where it should be rapidly photodissociated. It implies that there is a replenishment mechanism and that the observed gas is secondary. Past missions such as Herschel probed the atomic part of the gas through O I and C II emission lines. Gas science in debris discs is still in its infancy, and these new observations raise a handful of questions concerning the mechanisms to create the gas and about its evolution in the planetary system when it is released. The latter question will be addressed in this talk as a self-consistent gas evolution scenario is proposed and is compared to observations for the peculiar case of β Pictoris.Our model proposes that carbon and oxygen within debris discs are created due to photodissociation of CO which is itself created from the debris disc dust (due to grain-grain collisions or photodesorption). The evolution of the carbon atoms is modelled as viscous spreading, with viscosity parameterised using an α model. The temperature, ionisation fraction and population levels of carbon are followed with a PDR model called Cloudy, which is coupled to the dynamical viscous α model. Only carbon gets ionised due to its lower ionisation potential than oxygen. The carbon gas disc can end up with a high ionisation fraction due to strong FUV radiation field. A high ionisation fraction means that the magnetorotational instability (MRI) is very active, so that α is very high. Gas density profiles can be worked out for different input parameters such as the α value, the CO input rate, the location of the input and the incoming radiation field. Observability predictions can be made for future observations, and our model is tested on β Pictoris observations. This new gas evolution model fits the carbon and CO

  19. Grain size segregation in debris discs

    NASA Astrophysics Data System (ADS)

    Thebault, P.; Kral, Q.; Augereau, J.-C.

    2014-01-01

    Context. In most debris discs, dust grain dynamics is strongly affected by stellar radiation pressure. Because this mechanism is size-dependent, we expect dust grains to be spatially segregated according to their sizes. However, because of the complex interplay between radiation pressure, grain processing by collisions, and dynamical perturbations, this spatial segregation of the particle size distribution (PSD) has proven difficult to investigate and quantify with numerical models. Aims: We propose to thoroughly investigate this problem by using a new-generation code that can handle some of the complex coupling between dynamical and collisional effects. We intend to explore how PSDs behave in both unperturbed discs at rest and in discs pertubed by planetary objects. Methods: We used the DyCoSS code to investigate the coupled effect of collisions, radiation pressure, and dynamical perturbations in systems that have reached a steady-state. We considered two setups: a narrow ring perturbed by an exterior planet, and an extended disc into which a planet is embedded. For both setups we considered an additional unperturbed case without a planet. We also investigated the effect of possible spatial size segregation on disc images at different wavelengths. Results: We find that PSDs are always spatially segregated. The only case for which the PSD follows a standard dn ∝ s-3.5ds law is for an unperturbed narrow ring, but only within the parent-body ring itself. For all other configurations, the size distributions can strongly depart from such power laws and have steep spatial gradients. As an example, the geometrical cross-section of the disc is very rarely dominated by the smallest grains on bound orbits, as it is expected to be in standard PSDs in sq with q ≤ -3. Although the exact profiles and spatial variations of PSDs are a complex function of the set-up that is considered, we are still able to derive some reliable results that will be useful for image or SED

  20. Clinical and Radiological Characteristics of Lumbosacral Lateral Disc Herniation in Comparison With Those of Medial Disc Herniation

    PubMed Central

    Lee, Jung Hwan; Lee, Sang-Ho

    2016-01-01

    Abstract Lateral disc herniation (foraminal and extra foraminal) has clinical characteristics that are different from those of medial disc herniation (central and subarticular), including older age, more frequent radicular pain, and neurologic deficits. This is supposedly because lateral disc herniation mechanically irritates or compresses the exiting nerve root or dorsal root ganglion inside of a narrow canal more directly than medial disc herniation. The purpose of this study was to investigate clinical and radiological characteristics of lateral disc herniation in comparison with medial disc herniation. The 352 subjects diagnosed with localized lumbosacral disc herniation and followed up for at least 12 months after completion of treatment were included and divided into medial and lateral disc herniation groups, according to the anatomical location of the herniated disc in axial plain of magnetic resonance image. Clinical and radiological data were obtained and compared between the two groups. The lateral group included 74 (21%) patients and the medial group included 278 (79%). Mean age of the lateral group was significantly higher than that in the medial group. The lateral group showed a significantly larger proportion of patients with radiating leg pain and multiple levels of disc herniations than the medial group. No significant differences were found in terms of gender, duration of pain, pretreatment numeric rating scale, severity of disc herniation (protrusion and extrusion), and presence of weakness in leg muscles. The proportion of patients who underwent surgery was not significantly different between the 2 groups. However, the proportion of patients who accomplished successful pain reduction after treatment was significantly smaller in the lateral than in the medial group. In conclusion, patients with lateral disc herniation were older and had larger proportion of radiating leg pain than those with medial disc herniation. Lateral disc herniation was more

  1. Clinical and Radiological Characteristics of Lumbosacral Lateral Disc Herniation in Comparison With Those of Medial Disc Herniation.

    PubMed

    Lee, Jung Hwan; Lee, Sang-Ho

    2016-02-01

    Lateral disc herniation (foraminal and extra foraminal) has clinical characteristics that are different from those of medial disc herniation (central and subarticular), including older age, more frequent radicular pain, and neurologic deficits. This is supposedly because lateral disc herniation mechanically irritates or compresses the exiting nerve root or dorsal root ganglion inside of a narrow canal more directly than medial disc herniation. The purpose of this study was to investigate clinical and radiological characteristics of lateral disc herniation in comparison with medial disc herniation. The 352 subjects diagnosed with localized lumbosacral disc herniation and followed up for at least 12 months after completion of treatment were included and divided into medial and lateral disc herniation groups, according to the anatomical location of the herniated disc in axial plain of magnetic resonance image. Clinical and radiological data were obtained and compared between the two groups. The lateral group included 74 (21%) patients and the medial group included 278 (79%). Mean age of the lateral group was significantly higher than that in the medial group. The lateral group showed a significantly larger proportion of patients with radiating leg pain and multiple levels of disc herniations than the medial group. No significant differences were found in terms of gender, duration of pain, pretreatment numeric rating scale, severity of disc herniation (protrusion and extrusion), and presence of weakness in leg muscles. The proportion of patients who underwent surgery was not significantly different between the 2 groups. However, the proportion of patients who accomplished successful pain reduction after treatment was significantly smaller in the lateral than in the medial group. In conclusion, patients with lateral disc herniation were older and had larger proportion of radiating leg pain than those with medial disc herniation. Lateral disc herniation was more

  2. Acute aortic syndrome-pitfalls on gated and non-gated CT scan.

    PubMed

    Husainy, Mohammad Ali; Sayyed, Farhina; Puppala, Sapna

    2016-08-01

    Acute aortic syndrome (AAS) is a life-threatening condition which includes aortic dissection (AD), penetrating aortic ulcer (PAU) and intramural hematoma (IMH). Multi-detector computed tomography (MDCT) plays a crucial role in the diagnosis of this condition and for further clinical follow-up. It is important for radiologists to be aware of common pitfalls in cardiac-gated and non-gated CT in diagnosing AAS. They should also be wary of common mimics of AAS which may make a significant difference towards management of these patients. In this review, we present from our practice some of the common pitfalls and mimics of AAS on MDCT. PMID:27220654

  3. Modern high spatial resolution approaches to crustal evolution studies - pitfalls and progress

    NASA Astrophysics Data System (ADS)

    Whitehouse, M. J.

    2012-12-01

    Developments in analytical techniques for in situ geochronology and isotope geochemistry over the past few decades have contributed greatly to our understanding of the processes of Precambrian crustal evolution, plate tectonics, the development of Earth's hydrosphere and atmosphere and conditions for the development of life on Earth. The further back in time we go, however, the more complex the geology, requiring that we unravel and/or try to see through multiple phases of disturbance. Such geological complexity complicates interpretation and can lead to conflicting viewpoints on such key questions as when plate tectonics began on Earth, when it evolved to a process essentially similar to that of today and the nature and habitability of a potentially pre-plate tectonic Earth in the Hadean. This presentation will review, with case studies, some of the crucial aspects of applying and interpreting high spatial resolution in situ methods and some of the potential pitfalls. Obtaining accurate and precise geochronology is an essential first step in any study of Precambrian geology, whether it is the primary goal or provides a supporting framework to other diverse applications. To this end, high spatial resolution secondary ion mass spectrometry (SIMS) and laser ablation inductiively coupled plasma mass spectrometry (LA-ICPMS), typically combined with relevant imaging methods such as cathode luminescence (CL) are widely used to investigate the U-Pb systematics of complex zircon. In general precision is merely an analytical hurdle that we are good (and continually getting better) at clearing, but accuracy commonly contains not just an analytical element (e.g. calibration of standards) but also a considerable subjective element in order to unravel the commonly polyphase evolution of early Precambrian zircon. Examples of such problematic interpretations from the Neoarchean Lewisian Complex of northwest Scotland and the Paleoarchean Napier Complex of Antarctica will be

  4. Enhancement of Overgrowth by Gene Interactions in Lethal(2)giant Discs Imaginal Discs from Drosophila Melanogaster

    PubMed Central

    Buratovich, M. A.; Bryant, P. J.

    1997-01-01

    Recessive lethal mutations of the lethal(2)giant discs (l(2)gd) and lethal(2)fat (l(2)ft) loci of Drosophila melanogaster cause imaginal disc hyperplasia during a prolonged larval stage. Imaginal discs from l(2)ft l(2)gd or Gl(2)gd double homozygotes show more extensive overgrowth than in either single homozygote, and double homozygous l(2)ft l(2)gd mitotic clones in adult flies show much more overgrowth than is seen in clones homozygous for either l(2)gd or l(2)ft alone. dachsous (ds) also acts as an enhancer of l(2)gd, producing dramatically overgrown discs and causing failure to pupariate in double homozygotes. The comb gap (cg) mutation, which also interacts with ds, greatly enhances the tendency of imaginal discs from l(2)gd larvae to duplicate as they overgrow. If l(2)gd homozygotes are made heterozygous for l(2)ft, then several discs duplicate, indicating that l(2)ft acts as a dominant enhancer of l(2)gd. l(2)ft also acts as a dominant enhancer of l(2)gd, and conversely l(2)gd acts as a dominant modifier of l(2)ft. The enhancement of overgrowth caused by various mutant combinations is accompanied by changes in expression of Decapentaplegic and Wingless. These results show that tumor suppressor genes act in combination to control cell proliferation, and that tissue hyperplasia can be associated with ectopic expression of genes involved in pattern formation. PMID:9335602

  5. Role of Cytokines in Intervertebral Disc Degeneration: Pain and Disc-content

    PubMed Central

    Risbud, Makarand V.; Shapiro, Irving. M

    2014-01-01

    Degeneration of the intervertebral disc is the major contributor to back/neck and radicular pain. It is characterized by an elevation in levels of the inflammatory cytokines tumor necrosis factor (TNF)-α, interleukin (IL)-1 α/β, IL-6 and IL-17 secreted by the disc cells themselves; these cytokines promote matrix degradation, chemokine production and changes in cell phenotype. The resulting imbalance between catabolic and anabolic responses leads to degeneration, as well as herniation and radicular pain. Release of chemokines from degenerating discs promote infiltration and activation of T and B cells, macrophages, neutrophils, and mast cells further amplifying the inflammatory cascade. Immunocyte migration into the disc is accompanied by the appearance of microvasculature and nerve fibers arising from the dorsal root ganglion (DRG). In this inflammatory milieu, neurogenic factors in particular nerve growth factor (NGF) and brain-derive neurotrophic factor (BDNF) generated by disc and immune cells induce expression of pain associated cation channels in DRGs. Depolarization of these channels is likely to promote discogenic and radicular pain and reinforce the cytokine-mediated degenerative cascade. Taken together, the enhanced understanding of the contribution of cytokines and immune cells to catabolic and nociceptive processes provide new targets for treating symptomatic disc disease. PMID:24166242

  6. Antenna Controller Replacement Software

    NASA Technical Reports Server (NTRS)

    Chao, Roger Y.; Morgan, Scott C.; Strain, Martha M.; Rockwell, Stephen T.; Shimizu, Kenneth J.; Tehrani, Barzia J.; Kwok, Jaclyn H.; Tuazon-Wong, Michelle; Valtier, Henry; Nalbandi, Reza; Wert, Michael; Leung, Patrick

    2010-01-01

    The Antenna Controller Replacement (ACR) software accurately points and monitors the Deep Space Network (DSN) 70-m and 34-m high-efficiency (HEF) ground-based antennas that are used to track primarily spacecraft and, periodically, celestial targets. To track a spacecraft, or other targets, the antenna must be accurately pointed at the spacecraft, which can be very far away with very weak signals. ACR s conical scanning capability collects the signal in a circular pattern around the target, calculates the location of the strongest signal, and adjusts the antenna pointing to point directly at the spacecraft. A real-time, closed-loop servo control algorithm performed every 0.02 second allows accurate positioning of the antenna in order to track these distant spacecraft. Additionally, this advanced servo control algorithm provides better antenna pointing performance in windy conditions. The ACR software provides high-level commands that provide a very easy user interface for the DSN operator. The operator only needs to enter two commands to start the antenna and subreflector, and Master Equatorial tracking. The most accurate antenna pointing is accomplished by aligning the antenna to the Master Equatorial, which because of its small size and sheltered location, has the most stable pointing. The antenna has hundreds of digital and analog monitor points. The ACR software provides compact displays to summarize the status of the antenna, subreflector, and the Master Equatorial. The ACR software has two major functions. First, it performs all of the steps required to accurately point the antenna (and subreflector and Master Equatorial) at the spacecraft (or celestial target). This involves controlling the antenna/ subreflector/Master-Equatorial hardware, initiating and monitoring the correct sequence of operations, calculating the position of the spacecraft relative to the antenna, executing the real-time servo control algorithm to maintain the correct position, and

  7. Tearing up a misaligned accretion disc with a binary companion

    NASA Astrophysics Data System (ADS)

    Doğan, Suzan; Nixon, Chris; King, Andrew; Price, Daniel J.

    2015-05-01

    Accretion discs are common in binary systems, and they are often found to be misaligned with respect to the binary orbit. The gravitational torque from a companion induces nodal precession in misaligned disc orbits. We calculate whether this precession is strong enough to overcome the internal disc torques communicating angular momentum. For typical parameters precession wins: the disc breaks into distinct planes that precess effectively independently. We run hydrodynamical simulations to check these results, and confirm that disc breaking is widespread and generally enhances accretion on to the central object. This applies in many cases of astrophysical accretion, e.g. supermassive black hole binaries and X-ray binaries.

  8. Counterrotating perfect fluid discs as sources of electrovacuum static spacetimes

    NASA Astrophysics Data System (ADS)

    García-Reyes, Gonzalo; González, Guillermo A.

    2004-11-01

    The interpretation of some electrovacuum spacetimes in terms of counterrotating perfect fluid discs is presented. The interpretation is made by means of an 'inverse problem' approach used to obtain disc sources of known static solutions of the Einstein Maxwell equations. In order to do such an interpretation, a detailed study is presented of the counterrotating model (CRM) for generic electrovacuum static axially symmetric relativistic thin discs with nonzero radial pressure. Four simple families of models of counterrotating charged discs based on Chazy Curzon-type, Zipoy Voorhees-type, Bonnor Sackfield-type and charged and magnetized Darmois electrovacuum metrics are considered, where we obtain some discs with a well-behaved CRM.

  9. Geochemical databases: minding the pitfalls to avoid the pratfalls

    NASA Astrophysics Data System (ADS)

    Goldstein, S. L.; Hofmann, A. W.

    2011-12-01

    The field of geochemistry has been revolutionized in recent years by the advent of databases (PetDB, GEOROC, NAVDAT, etc). A decade ago, a geochemical synthesis required major time investments in order to compile relatively small amounts of fragmented data from large numbers of publications, Now virtually all of the published data on nearly any solid Earth topic can be downloaded to nearly any desktop computer with a few mouse clicks. Most solid Earth talks at international meetings show data compilations from these databases. Applications of the data are playing an increasingly important role in shaping our thinking about the Earth. They have changed some fundamental ideas about the compositional structure of the Earth (for example, showing that the Earth's "trace element depleted upper mantle" is not so depleted in trace elements). This abundance of riches also poses new risks. Until recently, important details associated with data publication (adequate metadata and quality control information) were given low priority, even in major journals. The online databases preserve whatever has been published, irrespective of quality. "Bad data" arises from many causes, here are a few. Some are associated with sample processing, including incomplete dissolution of refractory trace minerals, or inhomogeneous powders, or contamination of key elements during preparation (for example, this was a problem for lead when gasoline was leaded, and for niobium when tungsten-carbide mills were used to powder samples). Poor analytical quality is a continual problem (for example, when elemental abundances are at near background levels for an analytical method). Errors in published data tables (more common than you think) become bad data in the databases. The accepted values of interlaboratory standards change with time, while the published data based on old values stay the same. Thus the pitfalls associated with the new data accessibility are dangerous in the hands of the inexperienced

  10. Turbulence-induced disc formation in strongly magnetized cloud cores

    NASA Astrophysics Data System (ADS)

    Seifried, D.; Banerjee, R.; Pudritz, R. E.; Klessen, R. S.

    2013-07-01

    We present collapse simulations of strongly magnetized, turbulent molecular cloud cores with masses ranging from 2.6 to 1000 M⊙ in order to study the influence of the initial conditions on the turbulence-induced disc formation mechanism proposed recently by Seifried et al. We find that Keplerian discs are formed in all cases independently of the core mass, the strength of turbulence or the presence of global rotation. The discs appear within a few kyr after the formation of the protostar, are 50-150 au in size, and have masses between 0.05 and a few 0.1 M⊙. During the formation of the discs the mass-to-flux ratio stays well below the critical value of 10 for Keplerian disc formation. Hence, flux-loss alone cannot explain the formation of Keplerian discs. The formation of rotationally supported discs at such early phases is rather due to the disordered magnetic field structure and due to turbulent motions in the surroundings of the discs, two effects lowering the classical magnetic braking efficiency. Binary systems occurring in the discs are mainly formed via the disc capturing mechanism rather than via disc fragmentation, which is largely suppressed by the presence of magnetic fields.

  11. Dynamics of a disc in a nematic liquid crystal.

    PubMed

    Antipova, Alena; Denniston, Colin

    2016-01-28

    We use lattice Boltzmann simulations to study the dynamics of a disc immersed in a nematic liquid crystal. In the absence of external torques, discs with homeotropic anchoring align with their surface normal parallel to the director of the nematic liquid crystal. In the presence of a weak magnetic field a ferromagnetic disc will rotate to equilibrate the elastic torque due to the distortion of the nematic director and the magnetic torque. When the magnetic field rotates the disc so that the angle θ between normal to the surface of the disc â and director of the liquid crystal n[combining circumflex] becomes greater than π/2, the disc flips around the axis perpendicular to the rotation axis so that â sweeps through π radians. An analysis of this behaviour was performed. In particular, we look at the impact of the disc thickness and edges on defect creation and the flipping transition. We also analyse the importance of backflow. PMID:26575160

  12. Examination of turbine discs from nuclear power plants

    SciTech Connect

    Czajkowski, C.J.; Weeks, J.R.

    1982-01-01

    Investigations were performed on a cracked turbine disc from the Cooper Nuclear Power Station, and on two failed turbine discs (governor and generator ends) from the Yankee-Rowe Nuclear Power Station. Cooper is a boiling water reactor (BWR) which went into commercial operation in July 1974, and Yankee-Rowe is a pressurized water reactor (PWR) which went into commercial operation in June 1961. Cracks were identified in the bore of the Cooper disc after 41,913 hours of operation, and the disc removed for repair. At Yankee-Rowe two discs failed after 100,000 hours of operation. Samples of the Cooper disc and both Yankee-Rowe disc (one from the governor and one from the generator end of the LP turbine) were sent to Brookhaven National Laboratory (BNL) for failure analysis.

  13. Clinical experience in cell-based therapeutics: disc chondrocyte transplantation A treatment for degenerated or damaged intervertebral disc.

    PubMed

    Meisel, Hans Jörg; Siodla, Vilma; Ganey, Timothy; Minkus, Yvonne; Hutton, William C; Alasevic, Olivera J

    2007-02-01

    Disc herniation treated by discectomy results in a significant loss of nucleus material and disc height. Biological restoration through the use of autologous disc chondrocyte transplantation offers a potential to achieve functional integration of disc metabolism and mechanics. Chondrocytes that have been removed from damaged cartilaginous tissues maintain a capacity to proliferate, produce and secrete matrix components and respond to physical stimuli such as dynamic loading. Nucleus regeneration using autologous cultured disc-derived chondrocytes (ADCT) has been demonstrated in a canine model and in clinical pilot studies. In 2002 a prospective, controlled, randomised, multi-center study, EuroDISC, comparing safety and efficacy of autologous disc chondrocyte transplant, chondrotransplant DISC, plus discectomy (ADCT), with discectomy alone was initiated. A dog model was used to investigate the hypothesis that autologous disc chondrocytes can be used to repair damaged intervertebral disc. Disc chondrocytes were harvested and expanded in culture under controlled and defined conditions, returned to the same animals from which they had been sampled (autologous transplantation) via percutaneous delivery. The animals were analyzed at specific times after transplantation by several methods to examine whether disc chondrocytes integrated with the surrounding tissue, produced the appropriate intervertebral disc extracellular matrix, and might provide a formative solution to disc repair. The clinical goals of the EuroDISC study, were to provide long-term pain relief, maintain disc height and prevent adjacent segment disease. Interim analysis was performed after 2 years; Oswestry (low back pain/disability), Quebec Back-Pain Disability Scale, as well as Prolo and VAS score were used for the evaluation. Disc height was assessed by MRI. In the context of degenerative changes in an injury model: () autologous disc chondrocytes were expended in culture and returned to the disc by a

  14. Using your shoulder after replacement surgery

    MedlinePlus

    Joint replacement surgery - using your shoulder; Shoulder replacement surgery - after ... You have had shoulder replacement surgery to replace the bones of your shoulder joint with artificial parts. The parts include a stem made ...

  15. Structure formation in gas-rich galactic discs with finite thickness: from discs to rings

    NASA Astrophysics Data System (ADS)

    Behrendt, M.; Burkert, A.; Schartmann, M.

    2015-03-01

    Gravitational instabilities play an important role in structure formation of gas-rich high-redshift disc galaxies. In this paper, we revisit the axisymmetric perturbation theory and the resulting growth of structure by taking the realistic thickness of the disc into account. In the unstable regime, which corresponds for thick discs to a Toomre parameter below the critical value Q0, crit = 0.696, we find a fastest growing perturbation wavelength that is always a factor 1.93 times larger than in the classical razor-thin disc approximation. This result is independent of the adopted disc scaleheight and by this independent of temperature and surface density. In order to test the analytical theory, we compare it with a high-resolution hydrodynamical simulation of an isothermal gravitationally unstable gas disc with the typical vertical sech2 density profile and study its break up into rings that subsequently fragment into dense clumps. In the first phase, rings form, that organize themselves discretely, with distances corresponding to the local fastest growing perturbation wavelength. We find that the disc scaleheight has to be resolved initially with five or more grid cells in order to guarantee proper growth of the ring structures, which follow the analytical prediction. These rings later on contract to a thin and dense line, while at the same time accreting more gas from the inter-ring region. It is these dense, circular filaments, that subsequently fragment into a large number of clumps. Contrary to what is typically assumed, the clump sizes are therefore not directly determined by the fastest growing wavelength.

  16. Replacement Cost of Domestic Crude

    Energy Science and Technology Software Center (ESTSC)

    1994-12-01

    The DEEPWATER model forecasts the replacement cost of domestic crude oil for 13 offshore regions in the lower 48 states. The replacement cost of domestic crude oil is the constant or levelized selling price that will recover the full expense of exploration, development, and productions with a reasonable return on capital.

  17. Biomaterials in total joint replacement.

    PubMed

    Katti, Kalpana S

    2004-12-10

    The current state of materials systems used in total hip replacement is presented in this paper. An overview of the various material systems used in total hip replacement reported in literature is presented in this paper. Metals, polymers, ceramics and composites are used in the design of the different components of hip replacement implants. The merits and demerits of these material systems are evaluated in the context of mechanical properties most suitable for total joint replacement such as a hip implant. Current research on advanced polymeric nanocomposites and biomimetic composites as novel materials systems for bone replacement is also discussed. This paper examines the current research in the materials science and the critical issues and challenges in these materials systems that require further research before application in biomedical industry. PMID:15556342

  18. Learning to Teach with Two Mentors: Revisiting the "Two-Worlds Pitfall" in Student Teaching

    ERIC Educational Resources Information Center

    Smith, Emily R.; Avetisian, Virginia

    2011-01-01

    Research on learning to teach repeatedly cites the disjuncture in teaching practices promoted across universities and K-12 schools. Much of the literature that is focused on this "two-worlds pitfall" (Feiman-Nemser & Buchmann, 1985) describes the influence of cooperating teachers' more traditional teaching practices on teacher candidates'…

  19. Analysis of Factors Enhancing Pitfall in Research and Teaching of the Nigerian University System

    ERIC Educational Resources Information Center

    Ahmed, Tafida; Umar, Kasim; Paul, Chima

    2015-01-01

    The paper analyses factors enhancing pitfall in research and teaching in the Nigerian university system. Using data generated from secondary sources, it was found that so many factors are responsible for the constant decay in teaching and research in the Nigerian universities. The paper however found from literature that the high rate of pitfalls…

  20. The Pitfalls of Mobile Devices in Learning: A Different View and Implications for Pedagogical Design

    ERIC Educational Resources Information Center

    Ting, Yu-Liang

    2012-01-01

    Studies have been devoted to the design, implementation, and evaluation of mobile learning in practice. A common issue among students' responses toward this type of learning concerns the pitfalls of mobile devices, including small screen, limited input options, and low computational power. As a result, mobile devices are not always perceived by…

  1. Efficient sampling of ground-dwelling arthropods using pitfall traps in arid steppes.

    PubMed

    Cheli, Germán H; Corley, Juan C

    2010-01-01

    Pitfall trapping is probably the most frequently used method for sampling ground-dwelling arthropods. While the capture of specimens in pitfall traps largely depends on the number of individuals in the sampled area, trap design and trapping effort for a given environment, can also affect sampling success. The aim of this study was to determine the best pitfall trapping design for collecting ground-dwelling arthropods in the wind-blown and cold arid steppe areas of Patagonia. We tested four designs of traps, six types of preservative and different times of activation as well as the quantity of traps. Both preservation attributes and sampling efficiency differed between different trap designs and fluids compared. We conclude that in order to obtain reliable data on the structure of a community of ground-dwelling arthropods in Patagonia, at least three pitfall traps per experimental unit are required. In addition, traps should be opened for a minimum of 10 days filled with 300 ml of 30% ethylene glycol. We also suggested the use of a simple trap design (i. e. without funnel or roof). We believe these findings will contribute to more appropriate sampling of the ground dwelling fauna of Patagonia as well as other arid areas, leading to more reliable diversity studies. PMID:21271057

  2. Two new planthopper species (Hemiptera, Fulgoroidea, Caliscelidae) collected in pitfall traps in Zambia.

    PubMed

    Chmurova, Lucia; Webb, Michael D

    2016-01-01

    Two new species of planthoppers in the family Caliscelidae (Hemiptera: Fulgoroidea) are described from Zambia, i.e., Afronaso spinosa sp. n. and Calampocus zambiaensis sp. n. All specimens are flightless males and nearly all were collected from baited pitfall traps (except for one specimen collected from a yellow pan trap), suggesting that they live near to or on the ground. PMID:27615842

  3. Empathy and Social-Emotional Learning: Pitfalls and Touchstones for School-Based Programs

    ERIC Educational Resources Information Center

    Maxwell, Bruce; DesRoches, Sarah

    2010-01-01

    This chapter identifies three common pitfalls in the use of the concept of empathy in formal social-emotional learning interventions: (1) not distinguishing between affective and cognitive empathy ("equivocation"); (2) overestimating the role of the imagination in empathizing ("Piaget's fallacy"); and (3) not accommodating the developmental and…

  4. The Pitfalls of Valenced Labels and the Benefits of Properly Calibrated Psychological Flexibility

    ERIC Educational Resources Information Center

    McNulty, James K.; Fincham, Frank D.

    2012-01-01

    Replies to comments by Sonja Lyubomirsky (see record 2012-27130-008), Riva Guiseppe (see record 2012-27130-009), and Alan S. Waterman (see record 2012-27130-010) on the original article by McNulty and Fincham (see record 2011-15476-001) regarding the pitfalls of valenced labels and the benefits of properly calibrated psychological flexibility.

  5. Pitfalls and Promises: The Use of Secondary Data Analysis in Educational Research

    ERIC Educational Resources Information Center

    Smith, Emma

    2008-01-01

    This paper considers the use of secondary data analysis in educational research. It addresses some of the promises and potential pitfalls that influence its use and explores a possible role for the secondary analysis of numeric data in the "new" political arithmetic tradition of social research. Secondary data analysis is a relatively under-used…

  6. Who's the Boss?: The Possibilities and Pitfalls of Collaborative Administration for Untenured WPAs.

    ERIC Educational Resources Information Center

    Schell, Eileen E.

    1998-01-01

    Analyzes scholarship on administrative leadership styles. Describes the writing program co-directorship model the author and a colleague developed at a Southern public university, and offers a critical analysis of both the possibilities and pitfalls of collaborative administration for untenured writing program administrators. Points out ways in…

  7. Benefits and Pitfalls: Simple Guidelines for the Use of Social Networking Tools in K-12 Education

    ERIC Educational Resources Information Center

    Huffman, Stephanie

    2013-01-01

    The article will outline a framework for the use of social networking tools in K-12 education framed around four thought provoking questions: 1) what are the benefits and pitfalls of using social networking tools in P-12 education, 2) how do we plan effectively for the use of social networking tool, 3) what role does professional development play…

  8. Rewards & pitfalls of using treating pressure analysis for evaluating fracture design

    SciTech Connect

    Cramer, D.D.

    1996-12-31

    Analyzing pressures during a fracture treatment provides insight into the hydraulic fracturing process, and is widely used today. In this paper, case histories are reviewed and guidelines are presented to identify pitfalls and establish strategies in pressure-analysis methods and procedures.

  9. Inflammation in intervertebral disc degeneration and regeneration

    PubMed Central

    Molinos, Maria; Almeida, Catarina R.; Caldeira, Joana; Cunha, Carla; Gonçalves, Raquel M.; Barbosa, Mário A.

    2015-01-01

    Intervertebral disc (IVD) degeneration is one of the major causes of low back pain, a problem with a heavy economic burden, which has been increasing in prevalence as populations age. Deeper knowledge of the complex spatial and temporal orchestration of cellular interactions and extracellular matrix remodelling is critical to improve current IVD therapies, which have so far proved unsatisfactory. Inflammation has been correlated with degenerative disc disease but its role in discogenic pain and hernia regression remains controversial. The inflammatory response may be involved in the onset of disease, but it is also crucial in maintaining tissue homeostasis. Furthermore, if properly balanced it may contribute to tissue repair/regeneration as has already been demonstrated in other tissues. In this review, we focus on how inflammation has been associated with IVD degeneration by describing observational and in vitro studies as well as in vivo animal models. Finally, we provide an overview of IVD regenerative therapies that target key inflammatory players. PMID:25673296

  10. New Experiments with Spinning Metallic Discs

    NASA Technical Reports Server (NTRS)

    Mazuruk, Konstantin; Grugel, Richard N.

    2003-01-01

    A number of recent advanced theories related to torsion properties of the space-time matrix predict the existence of an interaction between classically spinning objects. Indeed, some experimental data suggest that spinning magnetic bodies discernibly interact with Earth's natural fields. If there are interactions between rotating bodies then nuclear spins could be used for detection. Thus, assuming a spinning body induces a hypothetical torsion field, a sensor based on the giant magnetoresistance effect would detect local changes. Experimentally, spinning a brass wheel shielded from Earth's magnetic field showed no measurable change in signals; with no shielding a Faraday disc phenomenon was observed. Unexpected experimental measurements from the non-axial Faraday disc configuration were recorded and a theoretical model was derived to explain them.

  11. [Diagnostics and therapy of spinal disc herniation].

    PubMed

    Zimmer, A; Reith, W

    2014-11-01

    Degenerative processes in a movement segment of the vertebral column, which can potentially give rise to herniation of elements of the nucleus pulposus, are complex and of variable clinical and radiological dimensions; however the mere assumption that degenerative changes precede disc herniation remains a matter of debate. By definition, spinal disc herniation (SDH) refers to components of the gelatinous nucleus pulposus protruding beyond the dorsal level of the vertebral body margin through tears in the annulus fibrosus. Clinical presentation may include pain, paresis and sensory disturbances. Magnetic resonance imaging (MRI) is considered the gold standard in the diagnosis of SDH. In the majority of patients a conservative approach with physical therapy exercises and adequate analgesic and antiphlogistic medical treatment results in a substantial improvement of symptoms. PMID:25398570

  12. Thalamic Pain Misdiagnosed as Cervical Disc Herniation

    PubMed Central

    Lim, Tae Ha; Choi, Soo Il; Yoo, Jee In; Choi, Young Soon; Lim, Young Su; Sang, Bo Hyun; Bang, Yun Sic

    2016-01-01

    Thalamic pain is a primary cause of central post-stroke pain (CPSP). Clinical symptoms vary depending on the location of the infarction and frequently accompany several pain symptoms. Therefore, correct diagnosis and proper examination are not easy. We report a case of CPSP due to a left acute thalamic infarction with central disc protrusion at C5-6. A 45-year-old-male patient experiencing a tingling sensation in his right arm was referred to our pain clinic under the diagnosis of cervical disc herniation. This patient also complained of right cramp-like abdominal pain. After further evaluations, he was diagnosed with an acute thalamic infarction. Therefore detailed history taking should be performed and examiners should always be aware of other symptoms that could suggest a more dangerous disease. PMID:27103967

  13. Planetesimal formation in self-gravitating discs

    NASA Astrophysics Data System (ADS)

    Gibbons, P. G.; Rice, W. K. M.; Mamatsashvili, G. R.

    2012-10-01

    We study particle dynamics in local two-dimensional simulations of self-gravitating accretion discs with a simple cooling law. It is well known that the structure which arises in the gaseous component of the disc due to a gravitational instability can have a significant effect on the evolution of dust particles. Previous results using global simulations indicate that spiral density waves are highly efficient at collecting dust particles, creating significant local overdensities which may be able to undergo gravitational collapse. We expand on these findings using a range of cooling times to mimic the conditions at a large range of radii within the disc. Here we use the PENCIL code to solve the 2D local shearing sheet equations for gas on a fixed grid together with the equations of motion for solids coupled to the gas solely through aerodynamic drag force. We find that spiral density waves can create significant enhancements in the surface density of solids, equivalent to 1-10 cm sized particles in a disc following the profiles of Clarke around an ˜1 M⊙ star, causing it to reach concentrations several orders of magnitude larger than the particles mean surface density. We also study the velocity dispersion of the particles, finding that the spiral structure can result in the particle velocities becoming highly ordered, having a narrow velocity dispersion. This implies low relative velocities between particles, which in turn suggest that collisions are typically low energy, lessening the likelihood of grain destruction. Both these findings suggest that the density waves that arise due to gravitational instabilities in the early stages of star formation provide excellent sites for the formation of large, planetesimal-sized objects.

  14. The Astral Curved Disc of Chevroches (France)

    NASA Astrophysics Data System (ADS)

    Devevey, F. Rousseau, A.

    2009-08-01

    The excavation of the unexplored secondary agglomeration in Chevroches (Nièvre), from 2001 to 2002, directed by F. Devevey (INRAP), has led to the discovery of an astrological bronze curved disc of a type unknown in the ancient world; it is inscribed with three lines in Greek transcribing Egyptian an Roman months, and the twelve signs of the zodiac. This article presents the first observations.

  15. Development of fluorescent multilayer disc structure

    NASA Astrophysics Data System (ADS)

    Beliak, Ievgen; Butenko, Larisa

    2011-09-01

    The fluorescent multilayer disc (FMD) consists of a substrate and the sandwich-structure of information and intermediate layers. While all the structure of the disc is transparent and homogeneous the parasitic signal will be caused mostly by photoluminescence (PL) and absorption of pits areas where laser light is unfocused. At large number of layers (10 or more) the noise level will get significant value, so it was suggested to derive readout signal as a variable one. Also it was proposed to record information only by the lands, to decrease the absorbance level and thus uncontrolled changing of the noise level. Furthermore in the FMD information layer there are inner and outside peripheral areas which hold a stable level of parasitic signal during readout from the edges of the disc. While the PL readout signal is spatially isotropic the optical head of the FMD drive receives just a part of the probing beam energy. PL quantum yield, absorption factor, receiver systems exposure loss coefficients are other reasons of the low PL signal. Thus the problem of the low SNR in this case is a major one and the only way of its solving is synthesis of the dye with a high PL quantum yield. The PL relaxation time on the other hand is a main feature of the data reading rate and therefore selection of the appropriate recording material will allow to bring this parameter in accordance to parameters of modern optical discs. To achieve this goal the composite organic pyrazoline dyes where synthesized and investigated as effective medium with a PL quantum yield up to 60-70%, relaxation time less than 100 ns, PL wide spectrum and opportunity of two-photon absorption. These parameters were further improved by a method based on the performance of organic dye molecules in the zeolite matrix.

  16. Superresolution technology applied to optical discs

    NASA Astrophysics Data System (ADS)

    Zhou, Changhe; Luo, Hongxin

    2005-09-01

    Smaller focal points are essential for the development of the next-generation optical disc. The size of focal point depends on the diffraction effect that is dependant on the numerical aperture of a lens and the wavelength of light. However, increase of the numerical aperture and decrease of the light wavelength will be ultimately limited due to the technical difficulty of fabricating a too-high NA lens and the too-short wavelength laser. In this paper, we report another approach of using the superresolution technology to compress the size of the so-called Airy spot for the next-generation optical disc, which is independent on the wavelength of laser. The superresolution phase plates are designed and fabricated with a microoptics technique. When such a phase plate is inserted into the optical system, the central spot at the focal plane of a lens is decreased to be 0.8 times of the Airy pattern, implying the possibility of reading higher storage density of optical discs. The most attractive feature is that the phase plate can be mass-produced at a very low cost, compared with the high cost of the high-numerical lens and/or the short wavelength laser. The disadvantages are that the inserted phase plate will induce the slight circular sidelobes around the central sport, so that it consumes a little more laser energy. The shortcoming could be overcome with suitable amendment. We have fabricated the phase plates with the surface-relief profile on a normal glass for phase modulation. Experimental results of superresolution effect with a low numerical aperture (NA=0.1) and a high-numerical lens (NA=0.8) are reported, which are in good agreement with the theoretical prediction. Superresolution technique should be highly interesting as a novel technique of the next-generation pickup head for reading the high storage of the optical discs.

  17. Friction in metal-on-metal total disc arthroplasty: effect of ball radius.

    PubMed

    Moghadas, Parshia; Mahomed, Aziza; Hukins, David W L; Shepherd, Duncan E T

    2012-02-01

    Total disc arthroplasty (TDA) can be used to replace a degenerated intervertebral disc in the spine. There are different designs of prosthetic discs, but one of the most common is a ball-and-socket combination. Contact between the bearing surfaces can result in high frictional torque, which can then result in wear and implant loosening. This study was designed to determine the effects of ball radius on friction. Generic models of metal-on-metal TDA were manufactured with ball radii of 10, 12, 14 and 16 mm, with a radial clearance of 0.015 mm. A simulator was used to test each sample in flexion-extension, lateral bending and axial rotation at frequencies of 0.25, 0.5, 0.75, 1, 1.25, 1.5, 1.75 and 2 Hz under loads of 50, 600, 1200 and 2000 N, in new born calf serum. Frictional torque was measured and Stribeck curves were plotted to illustrate the lubrication regime in each case. It was observed that implants with a smaller ball radius showed lower friction and showed boundary and mixed lubrication regimes, whereas implants with larger ball radius showed boundary lubrication only. This study suggests designing metal-on-metal TDAs with ball radius of 10 or 12 mm, in order to reduce wear and implant loosening. PMID:22177670

  18. Inner disc obscuration in GRS 1915+105 based on relativistic slim disc model

    NASA Astrophysics Data System (ADS)

    Vierdayanti, K.; Sadowski, A.; Mineshige, S.; Bursa, M.

    2013-11-01

    We study the observational signatures of the relativistic slim disc of 10 M⊙ black hole, in a wide range of mass accretion rate, dot{m}, dimensionless spin parameter, a*, and viewing angle, i. In general, the innermost temperature, Tin, increases with the increase of i for a fixed value of dot{m} and a*, due to the Doppler effect. However, for i > 50° and dot{m}>dot{m}_turn, Tin starts to decrease with the increase of dot{m}. This is a result of self-obscuration - the radiation from the innermost hot part of the disc is blocked by the surrounding cooler part. The value of dot{m}_turn and the corresponding luminosities depend on a* and i. Such obscuration effects cause an interesting behaviour on the disc luminosity (Ldisc)-Tin plane for high inclinations. In addition to the standard disc branch which appears below dot{m}_turn and which obeys L_disc ∝ T_in4 relation, another branch above dot{m}_turn, which is nearly horizontal, may be observed at luminosities close to the Eddington luminosity. We show that these features are likely observed in a Galactic X-ray source, GRS 1915+105. We support a high spin parameter (a* > 0.9) for GRS 1915+105 since otherwise the high value of Tin and small size of the emitting region (rin < 1rS) cannot be explained.

  19. Reactive thin film flows over spinning discs

    NASA Astrophysics Data System (ADS)

    Zhao, Kun; Wray, Alex; Yang, Junfeng; Matar, Omar

    2015-11-01

    We consider the dynamics of a thin film flowing over a spinning disc in the presence of a chemical reaction, and associated heat and mass transfer. We use a boundary-layer approximation in conjunction with the Karman-Polhausen approximation for the velocity distribution in the film to derive a set of coupled one-dimensional evolution equations for the film thickness, radial and azimuthal flow rates, concentration of the reagents and products, and temperature. These highly nonlinear partial differential equations are solved numerically to reveal the formation of large-amplitude waves that travel from the disc inlet to its periphery. The influence of these waves on the concentration and temperature profiles is analysed for a wide range of system parameters: the Damkohler and Schmidt numbers, the thermal Peclet numbers, and the dimensionless disc radius (a surrogate for the Eckman number). It is shown that these waves lead to significant enhancement of the rates of heat and mass transfer associated with the reactive flow; these are measured by tracking the temporal evolution of local and spatially-averaged Nusselt and Sherwood numbers, respectively. EPSRC Programme Grant, MEMPHIS, EP/K0039761/1.

  20. Risk Factors for Recurrent Lumbar Disc Herniation

    PubMed Central

    Huang, Weimin; Han, Zhiwei; Liu, Jiang; Yu, Lili; Yu, Xiuchun

    2016-01-01

    Abstract Recurrent lumbar disc herniation (rLDH) is a common complication following primary discectomy. This systematic review aimed to investigate the current evidence on risk factors for rLDH. Cohort or case-control studies addressing risk factors for rLDH were identified by search in Pubmed (Medline), Embase, Web of Science, and Cochrane library from inception to June 2015. Relevant results were pooled to give overall estimates if possible. Heterogeneity among studies was examined and publication bias was also assessed. A total of 17 studies were included in this systematic review. Risk factors that had significant relation with rLDH were smoking (OR 1.99, 95% CI 1.53–2.58), disc protrusion (OR 1.79, 95% CI 1.15–2.79), and diabetes (OR 1.19, 95% CI 1.06–1.32). Gender, BMI, occupational work, level, and side of herniation did not correlate with rLDH significantly. Based on current evidence, smoking, disc protrusion, and diabetes were predictors for rLDH. Patients with these risk factors should be paid more attention for prevention of recurrence after primary surgery. More evidence provided by high-quality observational studies is still needed to further investigate risk factors for rLDH. PMID:26765413