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Nicholas Ahn

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https://www.readbyqxmd.com/read/28966570/effects-of-environmental-enrichment-on-doublecortin-and-bdnf-expression-along-the-dorso-ventral-axis-of-the-dentate-gyrus
#1
Fabio Gualtieri, Catherine Brégère, Grace C Laws, Elena A Armstrong, Nicholas J Wylie, Theo T Moxham, Raphael Guzman, Timothy Boswell, Tom V Smulders
Adult hippocampal neurogenesis (AHN) in the dentate gyrus is known to respond to environmental enrichment, chronic stress, and many other factors. The function of AHN may vary across the septo-temporal axis of the hippocampus, as different subdivisions are responsible for different functions. The dorsal pole regulates cognitive-related behaviors, while the ventral pole mediates mood-related responses through the hypothalamic-pituitary-adrenal (HPA) axis. In this study, we investigate different methods of quantifying the effect of environmental enrichment on AHN in the dorsal and ventral parts of the dentate gyrus (dDG and vDG)...
2017: Frontiers in Neuroscience
https://www.readbyqxmd.com/read/28857967/the-effect-of-time-to-surgery-for-degenerative-lumbar-stenosis-dls-in-a-workers-compensation-setting
#2
Erik Y Tye, Joshua T Anderson, Arnold R Haas, Rick Percy, Stephen T Woods, Uri M Ahn, Nicholas U Ahn
STUDY DESIGN: Retrospective Cohort Study. OBJECTIVE: The objective of this study is to determine how time to surgery affects outcomes for degenerative lumbar stenosis (DLS) in a workers' compensation (WC) setting. SUMMARY OF BACKGROUND DATA: WC subjects are known to be a clinically distinct population with variable outcomes following lumbar surgery. No study has examined the effect of time to surgery in this clinically distinct population...
August 28, 2017: Clinical Spine Surgery
https://www.readbyqxmd.com/read/28856354/severity-weighting-of-postoperative-adverse-events-in-orthopedic-surgery
#3
Daniel D Bohl, Junyoung Ahn, Adam M Lukasiewicz, Andre M Samuel, Matthew L Webb, Bryce A Basques, Nicholas S Golinvaux, Kern Singh, Jonathan N Grauer
Studies of adverse events (AEs) after orthopedic surgery commonly use composite AE outcomes. An example of such an outcome is any AE. These types of outcomes treat AEs with different clinical significance (eg, death, urinary tract infection) similarly. We conducted a study to address this shortcoming in research methodology by creating a single severity-weighted outcome that can be used to characterize the overall severity of a given patient's postoperative course. All orthopedic faculty members at 2 academic institutions were invited to complete a severity-weighting exercise in which AEs were assigned a percentage severity of death...
July 2017: American Journal of Orthopedics
https://www.readbyqxmd.com/read/28837531/preoperative-opioid-use-is-a-predictor-of-poor-return-to-work-in-workers-compensation-patients-after-lumbar-diskectomy
#4
Jeffrey A O'Donnell, Joshua T Anderson, Arnold R Haas, Rick Percy, Stephen T Woods, Uri M Ahn, Nicholas U Ahn
STUDY DESIGN: Retrospective cohort. OBJECTIVE: Determine the impact of preoperative opioid use in workers' compensation (WC) patients undergoing lumbar diskectomy (LD). SUMMARY OF BACKGROUND DATA: The prevalence of back pain among opioid users approached 60%. Long term opioid dependence in spine surgery patients is roughly 20%. Despite pervasive use, there is no evidence to support long-term opioid analgesic use for back pain. METHODS: 10,592 patients received compensation from the Ohio Bureau of Workers' Compensation for a lumbar disc herniation between 2005-2012...
August 23, 2017: Spine
https://www.readbyqxmd.com/read/28700387/treatment-of-recurrent-lumbar-disc-herniation-with-or-without-fusion-in-workers-compensation-subjects
#5
Jeffrey A O'Donnell, Joshua T Anderson, Arnold R Haas, Rick Percy, Stephen T Woods, Uri M Ahn, Nicholas U Ahn
STUDY DESIGN: Retrospective cohort study. OBJECTIVE: To determine outcomes after reoperation discectomy with or without fusion surgery for recurrent lumbar disc herniation (RLDH) in the workers' compensation (WC) population. SUMMARY OF BACKGROUND DATA: RLDH is estimated to occur in 7% to 24% of patients after discectomy. There are two main surgical options after reherniation: a revision discectomy (RD), or an RD combined with fusion (RDF)...
July 15, 2017: Spine
https://www.readbyqxmd.com/read/28671665/asparagine-endopeptidase-cleaves-%C3%AE-synuclein-and-mediates-pathologic-activities-in-parkinson-s-disease
#6
Zhentao Zhang, Seong Su Kang, Xia Liu, Eun Hee Ahn, Zhaohui Zhang, Li He, P Michael Iuvone, Duc M Duong, Nicholas T Seyfried, Matthew J Benskey, Fredric P Manfredsson, Lingjing Jin, Yi E Sun, Jian-Zhi Wang, Keqiang Ye
Aggregated forms of α-synuclein play a crucial role in the pathogenesis of synucleinopathies such as Parkinson's disease (PD). However, the molecular mechanisms underlying the pathogenic effects of α-synuclein are not completely understood. Here we show that asparagine endopeptidase (AEP) cleaves human α-synuclein, triggers its aggregation and escalates its neurotoxicity, thus leading to dopaminergic neuronal loss and motor impairments in a mouse model. AEP is activated and cleaves human α-synuclein at N103 in an age-dependent manner...
August 2017: Nature Structural & Molecular Biology
https://www.readbyqxmd.com/read/28538083/preoperative-opioid-use-a-risk-factor-for-poor-return-to-work-status-after-single-level-cervical-fusion-for-radiculopathy-in-a-workers-compensation-setting
#7
Mhamad Faour, Joshua T Anderson, Arnold R Haas, Rick Percy, Stephen T Woods, Uri M Ahn, Nicholas U Ahn
STUDY DESIGN: Retrospective comparative case-control study. OBJECTIVES: The objectives of this study are: (1) How preoperative opioid use impacts RTW status after single-level cervical fusion for radiculopathy? and (2) What are other postsurgical outcomes affected by preoperative opioid use? SUMMARY OF BACKGROUND DATA: Opioid use has increased significantly in the past decade. The use of opioids has a drastic impact on workers' compensation population, an at-risk cohort for poorer surgical and functional outcomes than the general population...
May 19, 2017: Clinical Spine Surgery
https://www.readbyqxmd.com/read/28441686/surgical-and-functional-outcomes-after-multilevel-cervical-fusion-for-degenerative-disc-disease-compared-with-fusion-for-radiculopathy-a-study-of-workers-compensation-population
#8
Mhamad Faour, Joshua T Anderson, Arnold R Haas, Rick Percy, Stephen T Woods, Uri M Ahn, Nicholas U Ahn
STUDY DESIGN: Retrospective cohort comparative study. OBJECTIVE: To evaluate presurgical and surgical factors that affect return to work (RTW) status after multilevel cervical fusion, and to compare outcomes after multilevel cervical fusion for degenerative disc disease (DDD) versus radiculopathy. SUMMARY OF BACKGROUND DATA: Cervical fusion provides more than 90% of symptomatic relief for radiculopathy and myelopathy. However, cervical fusion for DDD without radiculopathy is considered controversial...
May 1, 2017: Spine
https://www.readbyqxmd.com/read/28187073/prolonged-preoperative-opioid-therapy-in-patients-with-degenerative-lumbar-stenosis-in-a-workers-compensation-setting
#9
Erik Y Tye, Joshua T Anderson, Mhamad Faour, Arnold R Haas, Rick Percy, Stephen T Woods, Uri M Ahn, Nicholas U Ahn
STUDY DESIGN: Retrospective cohort study. OBJECTIVE: To investigate the impact of prolonged opioid use in the preoperative treatment plan of degenerative lumbar stenosis (DLS). SUMMARY OF BACKGROUND DATA: Patients undergoing operative treatment for DLS with concomitant opioid use represent a clinically challenging population. The relative paucity of data on the relationship between preoperative opioid use and clinical outcomes in the workers' compensation (WC) population necessitates further study of this unique population...
October 1, 2017: Spine
https://www.readbyqxmd.com/read/27922573/vertebroplasty-and-return-to-work-for-thoracolumbar-fractures-within-the-workers-compensation-population
#10
Jay M Levin, Joshua T Anderson, Arnold R Haas, Rick Percy, Stephen T Woods, Uri M Ahn, Nicholas U Ahn
STUDY DESIGN: Retrospective cohort study OBJECTIVE.: Analyze efficacy of vertebroplasty and its affect on return to work (RTW) in a workers' compensation (WC) population SUMMARY OF BACKGROUND DATA.: Vertebroplasty remains a controversial treatment modality for vertebral compression fractures (VCFs). No studies have analyzed use of vertebroplasty in the clinically distinct WC population. METHODS: A total of 371 Ohio WC subjects were identified who sustained VCFs and were treated with either vertebroplasty or conservative medical therapy between 1993 and 2013 using Current Procedural Terminology procedural and International Classification of Diseases, Ninth Revision diagnosis codes...
December 2, 2016: Spine
https://www.readbyqxmd.com/read/27893897/imaging-of-glial-cell-activation-and-white-matter-integrity-in-brains-of-active-and-recently-retired-national-football-league-players
#11
Jennifer M Coughlin, Yuchuan Wang, Il Minn, Nicholas Bienko, Emily B Ambinder, Xin Xu, Matthew E Peters, John W Dougherty, Melin Vranesic, Soo Min Koo, Hye-Hyun Ahn, Merton Lee, Chris Cottrell, Haris I Sair, Akira Sawa, Cynthia A Munro, Christopher J Nowinski, Robert F Dannals, Constantine G Lyketsos, Michael Kassiou, Gwenn Smith, Brian Caffo, Susumu Mori, Tomas R Guilarte, Martin G Pomper
Importance: Microglia, the resident immune cells of the central nervous system, play an important role in the brain's response to injury and neurodegenerative processes. It has been proposed that prolonged microglial activation occurs after single and repeated traumatic brain injury, possibly through sports-related concussive and subconcussive injuries. Limited in vivo brain imaging studies months to years after individuals experience a single moderate to severe traumatic brain injury suggest widespread persistent microglial activation, but there has been little study of persistent glial cell activity in brains of athletes with sports-related traumatic brain injury...
January 1, 2017: JAMA Neurology
https://www.readbyqxmd.com/read/27831969/decompression-versus-decompression-and-fusion-for-degenerative-lumbar-stenosis-in-a-workers-compensation-setting
#12
Erik Y Tye, Joshua T Anderson, Arnold R Haas, Rick Percy, Stephen T Woods, Uri M Ahn, Nicholas U Ahn
STUDY DESIGN: A retrospective cohort study. OBJECTIVE: The aim of this study was to compare outcomes in Workers' compensation (WC) subjects receiving decompression alone versus decompression and fusion for the indication of degenerative spinal stenosis (DLS) without deformity or instability. SUMMARY OF BACKGROUND DATA: The use of a fusion procedure during lumbar decompression for DLS alone remains controversial. We hypothesize that WC subjects receiving fusion and decompression will return to work less and incur greater medical costs than subjects receiving decompression alone...
July 1, 2017: Spine
https://www.readbyqxmd.com/read/27797182/stable-metal-organic-framework-supported-niobium-catalysts
#13
Sol Ahn, Nicholas E Thornburg, Zhanyong Li, Timothy C Wang, Leighanne C Gallington, Karena W Chapman, Justin M Notestein, Joseph T Hupp, Omar K Farha
Developing structurally well-defined, supported oxide catalysts remains a significant challenge. Here, we report the grafting of Nb(V) oxide sites onto the nodes of the Zr-based metal organic framework (MOF) NU-1000 as a stable, well-defined catalyst support. Nb(V) oxide was deposited with loadings up to 1.6 mmol/g via two postsynthetic methods: atomic layer deposition in a MOF, and solution-phase grafting in a MOF. Difference envelope density measurements indicated that the two synthetic methods resulted in different local structures of the Nb(V) ions within NU-1000...
November 21, 2016: Inorganic Chemistry
https://www.readbyqxmd.com/read/27755643/neck-pain-preoperative-opioids-and-functionality-after-cervical-fusion
#14
Mhamad Faour, Joshua T Anderson, Arnold R Haas, Rick Percy, Stephen T Woods, Uri M Ahn, Nicholas U Ahn
The use of opioids among patients with workers' compensation claims is associated with tremendous costs, especially for patients who undergo spinal surgery. This study compared return-to-work rates after single-level cervical fusion for degenerative disk disease between patients who received opioids before surgery and patients who underwent fusion with no previous opioid use. All study subjects qualified for workers' compensation benefits for injuries sustained at work between 1993 and 2011. The study population included 281 subjects who underwent single-level cervical fusion for degenerative disk disease with International Classification of Diseases, Ninth Revision, and Current Procedural Terminology code algorithms...
January 1, 2017: Orthopedics
https://www.readbyqxmd.com/read/27684084/spondylolysis-and-end-plate-arthrosis-at-l5-s1-a-cadaveric-study
#15
Peter T McCunniff, Hojun Yoo, Charles Yu, Navkirat S Bajwa, Jason O Toy, Uri M Ahn, Nicholas Ahn
This study examined the effect of bilateral and unilateral L5 pars defects on the degree of disk degeneration at the L5-S1 level in cadaveric specimens. An observational study was performed of 690 cadaveric specimens selected at random. These specimens represent individuals who died between 1893 and 1938. The study included 558 male and 132 female cadavers. Of the 120 specimens with L5 spondylolysis, 95 cases were bilateral and 25 were unilateral. The remaining 544 specimens were used as the control cohort...
January 1, 2017: Orthopedics
https://www.readbyqxmd.com/read/27575040/calcaneocuboid-joint-arthritis-of-the-midfoot-precedes-tibiotalar-joint-arthritis
#16
Anthony Dugarte, Sahil Bharwani, HoJun Yoo, Alexander Vondra Boiwka, Charles C Yu, Navkirat S Bajwa, Jason O Toy, Jonathan E Tang, Uri Ahn, Nicholas Ahn
Surgical models have best shown the relationship between ankle and mid-foot osteoarthritis, although findings regarding the calcaneocuboid joint have varied. To the authors' knowledge, no studies have evaluated the relationship between degenerative changes across the tibiotalar and calcaneocuboid joints. The goal of this study was to determine whether such a relationship exists and which joint degenerates first. A single examiner evaluated 694 tibiotalar and calcaneocuboid joints to determine the presence of osteoarthritis...
November 1, 2016: Orthopedics
https://www.readbyqxmd.com/read/27398795/return-to-work-rates-after-single-level-cervical-fusion-for-degenerative-disc-disease-compared-with-fusion-for-radiculopathy-in-a-workers-compensation-setting
#17
COMPARATIVE STUDY
Mhamad Faour, Joshua T Anderson, Arnold R Haas, Rick Percy, Stephen T Woods, Uri M Ahn, Nicholas U Ahn
STUDY DESIGN: A retrospective comparative cohort study. OBJECTIVE: To compare return to work (RTW) rates for patients who underwent single-level cervical fusion for radiculopathy compared with fusion for degenerative disc disease (DDD) as an indication for surgery. SUMMARY OF BACKGROUND DATA: Studies have shown that workers' compensation subjects have less favorable surgical and functional outcomes compared with the general population. Cervical decompression and fusion have provided great results with relieving radicular symptoms...
July 15, 2016: Spine
https://www.readbyqxmd.com/read/27391855/discovery-of-a-selective-covalent-inhibitor-of-lysophospholipase-like-1-lyplal1-as-a-tool-to-evaluate-the-role-of-this-serine-hydrolase-in-metabolism
#18
Kay Ahn, Markus Boehm, Matthew F Brown, Jessica Calloway, Ye Che, Jinshan Chen, Kimberly F Fennell, Kieran F Geoghegan, Adam M Gilbert, Jemy A Gutierrez, Amit S Kalgutkar, Adhiraj Lanba, Chris Limberakis, Thomas V Magee, Inish O'Doherty, Robert Oliver, Brandon Pabst, Jayvardhan Pandit, Kevin Parris, Jeffrey A Pfefferkorn, Timothy P Rolph, Rushi Patel, Brandon Schuff, Veerabahu Shanmugasundaram, Jeremy T Starr, Alison H Varghese, Nicholas B Vera, Cecile Vernochet, Jiangli Yan
Lysophospholipase-like 1 (LYPLAL1) is an uncharacterized metabolic serine hydrolase. Human genome-wide association studies link variants of the gene encoding this enzyme to fat distribution, waist-to-hip ratio, and nonalcoholic fatty liver disease. We describe the discovery of potent and selective covalent small-molecule inhibitors of LYPLAL1 and their use to investigate its role in hepatic metabolism. In hepatocytes, selective inhibition of LYPLAL1 increased glucose production supporting the inference that LYPLAL1 is a significant actor in hepatic metabolism...
September 16, 2016: ACS Chemical Biology
https://www.readbyqxmd.com/read/27286049/ipsilateral-tibiotalar-joint-osteoarthritis-transferred-to-the-contralateral-tibiotalar-joint
#19
Anthony Dugarte, Sahil Bharwani, HoJun Yoo, Alexander Vondra Boiwka, Jonathan E Tang, Uri M Ahn, Nicholas U Ahn
Classically, it is thought that pain or disability in one leg can stress the contralateral leg, leading to similar symptoms. The mechanism of action for subsequent dysfunction in the healthy limb is thought to involve compensatory changes that are used as a means to reduce stance phase time on the injured limb. This is believed to increase the forces distributed across the healthy limb, ultimately leading to injury. This belief has been challenged, as supportive literature is sparse. The goal of this study was to determine whether an association between tibiotalar (TT) osteoarthritis (OA) in the right vs left lower extremity exists, and whether injury to one lower extremity leads to degeneration in the contralateral lower extremity...
July 1, 2016: Orthopedics
https://www.readbyqxmd.com/read/27224882/prolonged-preoperative-opioid-therapy-associated-with-poor-return-to-work-rates-after-single-level-cervical-fusion-for-radiculopathy-for-patients-receiving-workers-compensation-benefits
#20
Mhamad Faour, Joshua T Anderson, Arnold R Haas, Rick Percy, Stephen T Woods, Uri M Ahn, Nicholas U Ahn
STUDY DESIGN: Retrospective comparative cohort study. OBJECTIVE: Examine the effect of prolonged preoperative opioid use on return to work (RTW) status after single-level cervical fusion for radiculopathy. SUMMARY OF BACKGROUND DATA: The use of opioids has a dramatic effect in a workers' compensation population. The costs of claims that involved opioids in the management plan are catastrophic particularly for those undergoing spinal surgical procedure...
January 15, 2017: Spine
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