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Zhu Y, Xing H, Dai D, Kallmes D, Kadirvel R. O-038 Differential Inter-strain Susceptibility to Vertebrobasilar Dolichoectasia in a Mouse Model. J Neurointerv Surg 2016. [DOI: 10.1136/neurintsurg-2016-012589.38] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Tennant BR, Vanderkruk B, Dhillon J, Dai D, Verchere CB, Hoffman BG. Myt3 suppression sensitizes islet cells to high glucose-induced cell death via Bim induction. Cell Death Dis 2016; 7:e2233. [PMID: 27195679 PMCID: PMC4917670 DOI: 10.1038/cddis.2016.141] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Revised: 04/11/2016] [Accepted: 04/22/2016] [Indexed: 12/13/2022]
Abstract
Diabetes is a chronic disease that results from the body's inability to properly control circulating blood glucose levels. The loss of glucose homoeostasis can arise from a loss of β-cell mass because of immune-cell-mediated attack, as in type 1 diabetes, and/or from dysfunction of individual β-cells (in conjunction with target organ insulin resistance), as in type 2 diabetes. A better understanding of the transcriptional pathways regulating islet-cell survival is of great importance for the development of therapeutic strategies that target β-cells for diabetes. To this end, we previously identified the transcription factor Myt3 as a pro-survival factor in islets following acute suppression of Myt3 in vitro. To determine the effects of Myt3 suppression on islet-cell survival in vivo, we used an adenovirus to express an shRNA targeting Myt3 in syngeneic optimal and marginal mass islet transplants, and demonstrate that suppression of Myt3 impairs the function of marginal mass grafts. Analysis of grafts 5 weeks post-transplant revealed that grafts transduced with the shMyt3 adenovirus contained ~20% the number of transduced cells as grafts transduced with a control adenovirus. In fact, increased apoptosis and significant cell loss in the shMyt3-transduced grafts was evident after only 5 days, suggesting that Myt3 suppression sensitizes islet cells to stresses present in the early post-transplant period. Specifically, we find that Myt3 suppression sensitizes islet cells to high glucose-induced cell death via upregulation of the pro-apoptotic Bcl2 family member Bim. Taken together these data suggest that Myt3 may be an important link between glucotoxic and immune signalling pathways.
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Brinjikji W, Yong Hong D, Dai D, Schroeder DJ, Kallmes DF, Kadirvel R. Statins are not associated with short-term improved aneurysm healing in a rabbit model of unruptured aneurysms. J Neurointerv Surg 2016; 9:200-203. [DOI: 10.1136/neurintsurg-2016-012265] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Revised: 02/01/2016] [Accepted: 02/04/2016] [Indexed: 11/04/2022]
Abstract
BackgroundOwing to their anti-inflammatory effects and ability to stimulate production of extracellular matrix and chemotactic migration of mesenchymal progenitor cells, statins could potentially improve aneurysm healing after endovascular treatment.ObjectiveTo test the hypothesis that systemic administration of simvastatin would improve aneurysm healing in a rabbit model of unruptured intracranial aneurysms.MethodsExperimental aneurysms were created in female rabbits and were embolized with platinum coils. Six rabbits served as controls and six rabbits received oral administration of simvastatin. Digital subtraction angiography was used to evaluate stability after embolization. Subjects were euthanized 4 weeks after coil embolization. Histologic samples were examined with a grading system (0–12) based on neck and dome features. Aneurysm occlusion data were compared using a Student t test.ResultsNo significant differences in the mean aneurysm size were found between groups. No coil compaction occurred in either group. All aneurysms in both the statin and control groups showed stable occlusion. There were no significant differences in the histologic grade of occlusion in either group (statin group 2.6±0.8 vs control group 2.7±3.2, p=0.94).ConclusionsSystemic statin administration after platinum coil embolization of unruptured aneurysms in a rabbit model does not improve aneurysm occlusion rates at 4 weeks.
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Ding Y, Dai D, Kallmes DF, Schroeder D, Kealey CP, Gupta V, Johnson AD, Kadirvel R. Preclinical Testing of a Novel Thin Film Nitinol Flow-Diversion Stent in a Rabbit Elastase Aneurysm Model. AJNR Am J Neuroradiol 2016; 37:497-501. [PMID: 26494695 DOI: 10.3174/ajnr.a4568] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Accepted: 08/12/2015] [Indexed: 12/23/2022]
Abstract
BACKGROUND AND PURPOSE Thin film nitinol can be processed to produce a thin microporous sheet with a low percentage of metal coverage (<20%) and high pore attenuation (∼70 pores/mm(2)) for flow diversion. We present in vivo results from the treatment of experimental rabbit aneurysms by using a thin film nitinol-based flow-diversion device. MATERIALS AND METHODS Nineteen aneurysms in the rabbit elastase aneurysm model were treated with a single thin film nitinol flow diverter. Devices were also placed over 17 lumbar arteries to model perianeurysmal branch arteries of the intracranial circulation. Angiography was performed at 2 weeks (n = 7), 1 month (n = 8), and 3 months (n = 4) immediately before sacrifice. Aneurysm occlusion was graded on a 3-point scale (grade I, complete occlusion; grade II, near-complete occlusion; grade III, incomplete occlusion). Toluidine blue staining was used for histologic evaluation. En face CD31 immunofluorescent staining was performed to quantify neck endothelialization. RESULTS Markedly reduced intra-aneurysmal flow was observed on angiography immediately after device placement in all aneurysms. Grade I or II occlusion was noted in 4 (57%) aneurysms at 2-week, in 6 (75%) aneurysms at 4-week, and in 3 (75%) aneurysms at 12-week follow-up. All 17 lumbar arteries were patent. CD31 staining showed that 75% ± 16% of the aneurysm neck region was endothelialized. Histopathology demonstrated incorporation of the thin film nitinol flow diverter into the vessel wall and no evidence of excessive neointimal hyperplasia. CONCLUSIONS In this rabbit model, the thin film nitinol flow diverter achieved high rates of aneurysm occlusion and promoted tissue in-growth and aneurysm neck healing, even early after implantation.
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Watson-Fargie T, Dai D, MacLeod MJ, Reid JM. Comparison of predictive scores of symptomatic intracerebral haemorrhage after stroke thrombolysis in a single centre. J R Coll Physicians Edinb 2016; 45:127-32. [PMID: 26181528 DOI: 10.4997/jrcpe.2015.208] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
UNLABELLED Symptomatic intracerebral haemorrhage following thrombolysis for ischaemic stroke causes significant morbidity and mortality. This study assessed which of four risk scores (SEDAN, HAT, GRASPS and SITS) best predicts symptomatic intracerebral haemorrhage. METHODS Data from 431 patients treated at Aberdeen Royal Infirmary (2003-2013) were extracted from a thrombolysis database. Score performance was compared using area under the curve. RESULTS Any intracerebral haemorrhage occurred in 12% of patients (53/413); 11% fulfilling the SITS-MOST symptomatic intracerebral haemorrhage definition (6/53), 34% the ECASS II definition (18/53), and 43% the National Institute of Neurological Disorder and Stroke definition (23/53). Stroke severity, as defined by the National Institutes of Health Stroke Scale, significantly improved after 24 hours in patients without intracerebral haemorrhage, but not in those with. Significant symptomatic intracerebral haemorrhage predictors were age, glucose, stroke severity, hyperdense middle cerebral artery on CT scan, ASPECTS score and anti-platelet therapy. The haemorrhage after thrombolysis score performed best at predicting symptomatic intracerebral haemorrhage (area under the curve 0.67-0.78, p < 0.001). CONCLUSION The haemorrhage after thrombolysis score uses the least variables and has the best predictive value for symptomatic intracerebral haemorrhage. Using predictive scores for clinical decision making depends on estimation of overall benefits as well as risk.
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Ding YH, Dai D, Schroeder D, Kadirvel R, Kallmes DF. Experimental testing of the dual-layer Woven EndoBridge device using an elastase-induced aneurysm model in rabbits. Interv Neuroradiol 2016; 22:299-303. [PMID: 26847799 DOI: 10.1177/1591019916628202] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Accepted: 01/01/2016] [Indexed: 11/17/2022] Open
Abstract
The dual-layer Woven EndoBridge (WEB) device (WEB II) is designed to improve the performance of the first-generation WEB device. This study was performed to evaluate the acute and chronic performance of WEB II for aneurysm occlusion in an elastase-induced aneurysm model in rabbits. We implanted WEB II devices in 36 elastase-induced aneurysms and followed up for one, three, six, and 12 months. Degree of aneurysm occlusion at follow-up was graded on the Web Occlusion Scale (WOS): Grade A, complete aneurysm occlusion; Grade B, complete occlusion with recess filling; Grade C, residual neck filling; and Grade D, residual aneurysm filling. Hematoxylin and eosin staining was performed for histological assessment of aneurysm healing. Grades A, B, C, and D aneurysm occlusion at one-month follow-up were noted in three (17%), three (17%), eight (44%), and four (22%) of 18 cases, respectively. At the three-month time point Grades A, B, C, and D were shown in two (33%), two (33%), one (17%), and one (17%) aneurysms. Six months after treatment, one (17%), two (33%), two (33%), and one (17%) cases demonstrated Grades A, B, C, and D occlusion. At the 12-month time point, Grades B, C, and D were shown in three (50%), two (33%), and one (17%) aneurysms. Histologic evaluation showed progressive thrombus organization within aneurysm lumen from one to 12 months. These results indicated that the WEB II device can achieve high rates of aneurysm occlusion over time in experimental aneurysms.
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Dai D, Ding YH, Kelly M, Kadirvel R, Kallmes D. Histopathological findings following pipeline embolization in a human cerebral aneurysm at the basilar tip. Interv Neuroradiol 2016; 22:153-7. [PMID: 26842611 DOI: 10.1177/1591019915622165] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 11/08/2015] [Indexed: 11/15/2022] Open
Abstract
We report histopathological findings from a human cerebral aneurysm following treatment with a flow diverter. A 75-year-old male underwent flow diversion treatment (Pipeline Embolization Device (PED)) and coil embolization for treatment of an aneurysm at the basilar tip. At four months, angiography showed complete aneurysm occlusion; at 12 months angiography demonstrated that the aneurysm had reopened. The patient expired from brainstem compression. The aneurysm cavity was primarily filled with unorganized thrombus. Thick, interrupted neointima crossed the neck interface indicating blood flow into aneurysm through small channels. Along the parent artery the PED was covered by neointima having a measured thickness of 0.19 ± 0.01 mm; the maximal stenosis of the proximal parent artery was 27%. The perforating arteries that were crossed by the PED remained patent. Findings in this human case are similar to those in the elastase-induced aneurysms in rabbits.
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Rouchaud A, Brinjikji W, Ding YH, Dai D, Zhu YQ, Cloft HJ, Kallmes DF, Kadirvel R. Evaluation of the Angiographic Grading Scale in Aneurysms Treated with the WEB Device in 80 Rabbits: Correlation with Histologic Evaluation. AJNR Am J Neuroradiol 2016; 37:324-9. [PMID: 26405081 DOI: 10.3174/ajnr.a4527] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Accepted: 07/14/2015] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE The WEB Occlusion Score has been proposed to assess angiographic outcomes for intracranial aneurysms treated with the Woven EndoBridge (WEB) device. Using a large series of experimental aneurysms treated with the WEB, we had the following objectives: 1) to compare angiographic outcomes as measured by the WEB Occlusion Scale with histologic results, and 2) to assess interobserver and intraobserver agreement of the WEB Occlusion Scale. MATERIALS AND METHODS Intracranial aneurysms were created in 80 rabbits and treated with WEB devices. Animals were sacrificed at last follow-up for histologic evaluation. DSA was performed just after the deployment of the device and at follow-up. Four investigators independently and retrospectively graded the DSA twice according to the WEB Occlusion Scale. One histopathologist blinded to the angiographic results graded the occlusion according to a 4-point scale patterned on the WEB Occlusion Scale. Intra- and interobserver agreement were evaluated for DSA. Follow-up angiographic grading and histologic reference were compared to determine the WEB Occlusion Scale accuracy for complete (with or without recess filling) versus incomplete occlusion and adequate (complete occlusion or neck remnant) versus inadequate occlusion. RESULTS Inter- and intraobserver weighted κ for the angiographic WEB Occlusion Scale were, respectively, 0.76 and 0.76, indicating substantial agreement. The sensitivity and specificity of the WEB Occlusion Scale for complete occlusion at follow-up compared with the histologic reference standard were, respectively, 75% and 83.3%, with an overall accuracy of 80%. Similarly, for adequate occlusion at follow-up, sensitivity was 97.7%, specificity was 64.9%, and overall accuracy was 82.5%. CONCLUSIONS The WEB Occlusion Scale appears to be consistent, reliable, and accurate compared with a histologic reference standard.
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Rouchaud A, Johnson CR, Thielen EP, Schroeder DJ, Ding YH, Dai D, Cebral J, Kallmes DF, Kadirvel R. Abstract WMP27: Differential Gene Expression in Coiled Versus Flow-diverter Treated Aneurysms: a RNA-Seq Analysis in Rabbit Aneurysm Model. Stroke 2016. [DOI: 10.1161/str.47.suppl_1.wmp27] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Introduction:
Numerous endovascular tools exist for the treatment of intracranial aneurysms with an increased use of flow-diverting devices in recent years. However, the biological mechanisms leading to aneurysm healing or potential complications such as delayed aneurysm ruptures after flow-diverter treatment are not yet well established. We used RNA-sequencing technology to identify genes relevant for biological impact of coils and flow-diverters in elastase-induced saccular aneurysms in rabbits and to identify genes and pathways of potential clinical interest.
Methods:
Elastase-induced saccular aneurysms were created at the origin of the right common carotid artery. Aneurysms were treated with coils (n=5) or flow-diverters (Pipeline Embolic Device, Covidien, CA) (n=4). Untreated aneurysms (n=6) were used as controls. Messenger RNA and microRNA were isolated from the aneurysms at 4 weeks following treatment. RNA samples were processed using RNA-seq technology. RNA-seq results were analyzed by using the Ingenuity Pathway Analysis tool.
Results:
Using RNA sequencing for coiled versus non-treated aneurysms, 464 genes were found to be differentially expressed with 58 genes down regulated and 406 genes up regulated. Using the same criteria for the flow-diverter treated aneurysms, 177 genes were found to be differentially expressed with 8 genes down regulated and 169 genes up regulated. Comparing coiled versus flow-diverter treated aneurysms, 13 genes were significantly differentially expressed with 8 down regulated and 5 up regulated genes. Genes identified with the highest interest for aneurysms healing were fibroblast growth factor-23, matrix metalloproteinases (MMP)-1, Scinderin and Basigin (implicated in MMP-2 and MMP-9 regulation). Pathway analysis associated these genes with inflammatory response, cellular migration, and coagulation, among other functions.
Conclusions:
RNA-sequencing analysis of rabbit aneurysms revealed differential regulation of some key pathways, including inflammation and cellular migration that could explain the different biological mechanisms implicated in aneurysms healing either after coiling or flow-diverter treatments and could explain potential device-related complications.
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Rouchaud A, Johnson C, Thielen E, Schroeder D, Ding YH, Dai D, Brinjikji W, Cebral J, Kallmes DF, Kadirvel R. Differential Gene Expression in Coiled versus Flow-Diverter-Treated Aneurysms: RNA Sequencing Analysis in a Rabbit Aneurysm Model. AJNR Am J Neuroradiol 2015; 37:1114-21. [PMID: 26721773 DOI: 10.3174/ajnr.a4648] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Accepted: 11/10/2015] [Indexed: 12/23/2022]
Abstract
BACKGROUND AND PURPOSE The biologic mechanisms leading to aneurysm healing or rare complications such as delayed aneurysm ruptures after flow-diverter placement remain poorly understood. We used RNA sequencing following implantation of coils or flow diverters in elastase aneurysms in rabbits to identify genes and pathways of potential interest. MATERIALS AND METHODS Aneurysms were treated with coils (n = 5) or flow diverters (n = 4) or were left untreated for controls (n = 6). Messenger RNA was isolated from the aneurysms at 4 weeks following treatment. RNA samples were processed by using RNA-sequencing technology and were analyzed by using the Ingenuity Pathway Analysis tool. RESULTS With RNA sequencing for coiled versus untreated aneurysms, 464/9990 genes (4.6%) were differentially expressed (58 down-regulated, 406 up-regulated). When we compared flow-diverter versus untreated aneurysms, 177/10,041 (1.8%) genes were differentially expressed (8 down-regulated, 169 up-regulated). When we compared flow-diverter versus coiled aneurysms, 13/9982 (0.13%) genes were differentially expressed (8 down-regulated, 5 up-regulated). Keratin 8 was overexpressed in flow diverters versus coils. This molecule may potentially play a critical role in delayed ruptures due to plasmin production. We identified overregulation of apelin in flow diverters, supporting the preponderance of endothelialization, whereas we found overexpression of molecules implicated in wound healing (dectin 1 and hedgehog interacting protein) for coiled aneurysms. Furthermore, we identified metallopeptidases 1, 12, and 13 as overexpressed in coiled versus untreated aneurysms. CONCLUSIONS We observed different physiopathologic responses after endovascular treatment with various devices. Flow diverters promote endothelialization but express molecules that could potentially explain the rare delayed ruptures. Coils promote wound healing and express genes potentially implicated in the recurrence of coiled aneurysms.
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Holcomb M, Ding YH, Dai D, McDonald RJ, McDonald JS, Kallmes DF, Kadirvel R. RNA-Sequencing Analysis of Messenger RNA/MicroRNA in a Rabbit Aneurysm Model Identifies Pathways and Genes of Interest. AJNR Am J Neuroradiol 2015; 36:1710-5. [PMID: 26228879 DOI: 10.3174/ajnr.a4390] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Accepted: 01/30/2015] [Indexed: 12/23/2022]
Abstract
BACKGROUND AND PURPOSE Rabbit aneurysm models are used for the testing of embolization devices and elucidating the mechanisms of human intracranial aneurysm growth and healing. We used RNA-sequencing technology to identify genes relevant to induced rabbit aneurysm biology and to identify genes and pathways of potential clinical interest. This process included sequencing microRNAs, which are important regulatory noncoding RNAs. MATERIALS AND METHODS Elastase-induced saccular aneurysms were created at the origin of the right common carotid artery in 6 rabbits. Messenger RNA and microRNA were isolated from the aneurysm and from the control left common carotid artery at 12 weeks and processed by using RNA-sequencing technology. The results from RNA sequencing were analyzed by using the Ingenuity Pathway Analysis tool. RESULTS A total of 9396 genes were analyzed by using RNA sequencing, 648 (6.9%) of which were found to be significantly differentially expressed between the aneurysms and control tissues (P < .05; false-discovery rate, <0.01; fold change, >2 or <.5). Of these genes, 614 were mapped successfully, 143 were down-regulated, and 471 were up-regulated in the aneurysms as compared with controls. Using the same criteria for significance, 3 microRNAs were identified as down-regulated and 5 were identified as up-regulated. Pathway analysis associated these genes with inflammatory response, cellular migration, and coagulation, among other functions and pathologies. CONCLUSIONS RNA-sequencing analysis of rabbit aneurysms revealed differential regulation of some key pathways, including inflammation and antigen presentation. ANKRD1 and TACR1 were identified as genes of interest in the regulation of matrix metalloproteinases.
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Kallmes D, Kadirvel R, Ding Y, Dai D, Kealey C, Gupta V, Johnson D. E-026 pre-clinical testing of a novel thin film nitinol flow diversion stent in a rabbit elastase aneurysm model. J Neurointerv Surg 2015. [DOI: 10.1136/neurintsurg-2015-011917.101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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88
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Rouchaud A, Dai D, Ding Y, Brinjikji W, Zhu Y, Lingineni R, Kallmes D, Kadirvel R. P-021 evaluation of angiographic grading scale in aneurysms treated with web device in 80 rabbits: correlation with histological evaluation. J Neurointerv Surg 2015. [DOI: 10.1136/neurintsurg-2015-011917.60] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Ding Y, Dai D, Schroeder D, Kadirvel R, Kallmes D. O-023 experimental testing of new generation of woven endobridge devices in elastase-induced aneurysms in rabbits. J Neurointerv Surg 2015. [DOI: 10.1136/neurintsurg-2015-011917.23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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90
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Wong K, Ho K, Dai D, Hung L, Chan K, Chan K. Preventive measure of second hip fracture: identification of high risk group. Physiotherapy 2015. [DOI: 10.1016/j.physio.2015.03.050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Ji Y, Chen S, Zhao L, Pan P, Wang L, Cai J, Dai D, Hu G, Cai JP, Huang H. In vitro
assessment of 39 CYP2C9
variants found in the Chinese population on the metabolism of the model substrate fluoxetine and a summary of their effects on other substrates. J Clin Pharm Ther 2015; 40:320-7. [PMID: 25884291 DOI: 10.1111/jcpt.12267] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Accepted: 03/04/2015] [Indexed: 12/01/2022]
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Dai D, Kadirvel R, Rezek I, Ding YH, Lingineni R, Kallmes D. Elastase-Induced Intracranial Dolichoectasia Model in Mice. Neurosurgery 2015; 76:337-43; discussion 343. [DOI: 10.1227/neu.0000000000000615] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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Dai D, Ding YH, Rezek I, Kallmes DF, Kadirvel R. Characterizing patterns of endothelialization following coil embolization: a whole-mount, dual immunostaining approach. J Neurointerv Surg 2015; 8:402-6. [PMID: 25646129 DOI: 10.1136/neurintsurg-2014-011513] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2014] [Accepted: 01/13/2015] [Indexed: 11/03/2022]
Abstract
BACKGROUND The extent, rate, and source of endothelialization following coil embolization of saccular aneurysms remains poorly understood. We performed a whole tissue mount, dual immunohistochemical analysis of experimental aneurysms to characterize the state of endothelialization over time after platinum coil embolization. METHOD AND MATERIAL Elastase-induced rabbit aneurysms were created and treated with bare platinum coils. Samples were harvested at 4 and 8 weeks (n=6 for each). En face whole tissue mount staining with antibodies to CD31 and α-smooth muscle actin was used to identify endothelial cells and smooth muscle cells, respectively. Sytox green stain was used to demonstrate nuclear morphology for identification of inflammatory cells. The extent of endothelialization was measured in relation to the aneurysm neck-parent artery interface. RESULTS At 4 weeks after coil embolization, very localized membranous tissue and neoendothelial cells were detected on the coil loops immediately adjacent to the parent artery-neck interface, but the remainder of the coil loops remained devoid of endothelial cells. At 8 weeks neoendothelial cells were more confluent over the coils than at 4 weeks, and extended up to 900 µm from the parent artery-neck interface. However, the surfaces of the coils farther away than this region harbored no endothelial cells. Scattered inflammatory cells, including neutrophils and monocytes, were seen on the coil surface at the neck central area, where the coil surface was bare at the 4 and 8 weeks' follow-up. CONCLUSIONS Platinum coil embolization supports gradual but limited endothelialization, where endothelial cells migrate directly from the adjacent parent artery.
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Puffer C, Ding YH, Dai D, Cebral J, Kallmes D, Kadirvel R. Abstract W P78: Gene Expression Comparison of Flow Diversion and Coiling in an Experimental Aneurysm Model. Stroke 2015. [DOI: 10.1161/str.46.suppl_1.wp78] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Backgound and Purpose:
Mechanisms of both healing and complications, including spontaneous aneurysm rupture, remain unclear following flow diverter treatment. The aim of the current study was to compare the gene expression of various key molecules involved in the healing of aneurysms between aneurysms treated with microcoils and flow diverters.
Methods:
Saccular aneurysms were created in rabbits (n=12). Aneurysms were either treated with coils (n=6) or with flow diverters (n=6). Aneurysm tissue was harvested at four weeks following treatment and used for gene expression and zymography experiments. Genes with a fold change of 1.2 or greater were considered up regulated, whereas those with a fold change of 0.8 or less were considered down regulated.
Results:
All coil embolized aneurysms were completely occluded at follow up. Two aneurysms were occluded and the remaining four samples were incompletely occluded in the flow diverter treated group. The following genes were expressed at lower levels in the flow diverter group as compared to the coiled aneurysm group: genes encoding proteinases (matrix metalloproteinases -2 and -9), cellular markers (endothelial nitric oxide synthase and smooth muscle actin), and structural proteins (collagens and fibronectin). Genes related to inflammation (tumor necrosis factor-α and monocyte chemoattractant protein -1) were up regulated in flow diverter treated aneurysms compared to coil embolized aneurysms. Notably, the enzymatic activity of active MMP-9 was high in aneurysms treated with flow diverters.
Conclusion:
As compared to coiled aneurysms, the molecular milieu surrounding aneurysms treated with flow diverters is characterized by higher levels of activated proteases, elevated expression of genes encoding inflammatory proteins, and diminished expression of genes encoding structural proteins. These data may provide improved understanding of rupture risk and healing following aneurysm treatment, and inform development of therapies aimed at lowering rupture risk and accelerating healing.
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Holcomb M, Ding YH, Dai D, McDonald R, McDonald J, Kallmes D, Kadirvel R. Abstract W MP45: RNA-seq Analysis of mRNA/miRNA in Rabbit Aneurysm Model Reveals Similar Expression Patterns to Human Intracranial Aneurysms. Stroke 2015. [DOI: 10.1161/str.46.suppl_1.wmp45] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background and Purpose:
Rabbit aneurysm models are used in the testing of embolization devices as well as elucidating the mechanisms human intracranial aneurysm growth and healing. We employed ribonucleic acid sequencing (RNA-seq) technology to identify genes relevant to induced rabbit aneurysm biology and compare these with genes related to human intracranial aneurysms to identify genes of potential clinical interest. This included sequencing micro RNA, which are important regulatory non-coding RNA.
Materials and Methods:
Elastase-induced saccular aneurysms were created at the origin of the right common carotid artery (CCA) in 5 rabbits. Messenger ribonucleic acid (mRNA) and micro ribonucleic acid (miRNA) was isolated from the aneurysm and the control unoperated left CCA at 12 weeks and was processed using RNA-seq technology. The results from RNA-seq were analyzed using Ingenuity Pathway Analysis.
Results:
9396 genes were analyzed using RNA-seq, of which 649 (6.9%) were found to be significantly differentially expressed between aneurysm and control tissues (p < 0.05, false discovery rate 2). Of these, 500 were up-regulated in the aneurysm and 149 were down-regulated as compared to controls. Using the same criteria, 3 miRNA were identified as down regulated and 5 were identified as up regulated. Pathway analysis associated these genes with inflammatory response, cellular migration, and coagulation, among other functions and pathologies.
Conclusion:
RNA-seq next-gen analysis of rabbit aneurysms shows similarities to human intracranial aneurysms with respect to regulation of some key pathways.
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Hodis S, Ding YH, Dai D, Lingineni R, Mut F, Cebral J, Kallmes D, Kadirvel R. Relationship between aneurysm occlusion and flow diverting device oversizing in a rabbit model. J Neurointerv Surg 2014; 8:94-8. [PMID: 25387731 DOI: 10.1136/neurintsurg-2014-011487] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2014] [Accepted: 10/24/2014] [Indexed: 11/03/2022]
Abstract
BACKGROUND AND PURPOSE Implanted, actual flow diverter pore density is thought to be strongly influenced by proper matching between the device size and parent artery diameter. The objective of this study was to characterize the correlation between device sizing, metal coverage, and the resultant occlusion of aneurysms following flow diverter treatment in a rabbit model. METHODS Rabbit saccular aneurysms were treated with flow diverters (iso-sized to proximal parent artery, 0.5 mm oversized, or 1.0 mm oversized, respectively, n=6 for each group). Eight weeks after implantation, the angiographic degree of aneurysm occlusion was graded (complete, near-complete, or incomplete). The ostium of the explanted aneurysm covered with the flow diverter struts was photographed. Based on gross anatomic findings, the metal coverage and pore density at the ostium of the aneurysm were calculated and correlated with the degree of aneurysm occlusion. RESULTS Angiographic results showed there were no statistically significant differences in aneurysm geometry and occlusion among groups. The mean parent artery diameter to flow diverter diameter ratio was higher in the 1.0 mm oversized group than in the other groups. Neither the percentage metal coverage nor the pore density showed statistically significant differences among groups. Aneurysm occlusion was inversely correlated with the ostium diameter, irrespective of the size of the device implanted. CONCLUSIONS Device sizing alone does not predict resultant pore density or metal coverage following flow diverter implantation in the rabbit aneurysm model. Aneurysm occlusion was not impacted by either metal coverage or pore density, but was inversely correlated with the diameter of the ostium.
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Puffer C, Dai D, Ding YH, Cebral J, Kallmes D, Kadirvel R. Gene expression comparison of flow diversion and coiling in an experimental aneurysm model. J Neurointerv Surg 2014; 7:926-30. [PMID: 25332413 DOI: 10.1136/neurintsurg-2014-011452] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Accepted: 09/29/2014] [Indexed: 11/04/2022]
Abstract
BACKGROUND AND PURPOSE Mechanisms of both healing and complications, including spontaneous aneurysm rupture, remain unclear following flow diverter treatment. The aim of this study was to compare gene expression of various key molecules involved in the healing of aneurysms, between aneurysms treated with microcoils and flow diverters. METHODS Saccular aneurysms were created in rabbits. Aneurysms were treated with coils (n=6) or flow diverters (n=6). Aneurysms were harvested at 4 weeks following treatment and used for gene expression and zymography experiments. Genes with a fold change of 1.2 or more were considered upregulated whereas those with a fold change of 0.8 or less were considered downregulated. RESULTS All coil embolized aneurysms were completely occluded at follow-up. Two aneurysms were occluded and the remaining four samples were incompletely occluded in the flow diverter treated group. The following genes were expressed at lower levels in the flow diverter group compared with the coiled aneurysm group: proteinases (matrix metalloproteinases 2 and 9), cellular markers (endothelial nitric oxide synthase and smooth muscle actin), and structural proteins (collagens and fibronectin). Genes related to inflammation (tumor necrosis factor α and monocyte chemoattractant protein 1) were upregulated in flow diverter treated aneurysms compared with coil embolized aneurysms. Notably, the enzymatic activity of active matrix metalloproteinase 9 was high in aneurysms treated with flow diverters. CONCLUSIONS Our findings may provide improved understanding of rupture risk and healing following aneurysm treatment and inform development of therapies aimed at lowering rupture risk and accelerating healing.
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Zhang Z, Dai D, Yu K, Yuan F, Jin J, Ding L, Hao Y, Liang F, Liu N, Zhao X, Long J, Xi Y, Sun YY. Association of HLA-B27 and ERAP1 with ankylosing spondylitis susceptibility in Beijing Han Chinese. ACTA ACUST UNITED AC 2014; 83:324-9. [PMID: 24666027 DOI: 10.1111/tan.12334] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2013] [Revised: 02/11/2014] [Accepted: 02/13/2014] [Indexed: 12/30/2022]
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Kadirvel R, Ding YH, Dai D, Rezek I, Lewis DA, Kallmes DF. Cellular mechanisms of aneurysm occlusion after treatment with a flow diverter. Radiology 2013; 270:394-9. [PMID: 24086073 DOI: 10.1148/radiol.13130796] [Citation(s) in RCA: 153] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
PURPOSE To characterize the progression of healing across aneurysm necks following treatment with a flow diverter in a rabbit aneurysm model. MATERIALS AND METHODS With institutional animal care and use committee approval, saccular aneurysms were created in 20 rabbits and treated with flow diverters. On days 1, 3, and 7 and weeks 4 and 8 after implantation, the aneurysm and the device-implanted vessel were harvested. En face staining of the gross specimen was performed for endothelial cells, endothelial progenitor cells, smooth muscle cells, and inflammatory cells. RESULTS The parent artery segments covered by the flow diverters were completely devoid of endothelial cells at 1 and 3 days but had completely reendothelialized by 7 days. At all time points, the struts along the patent portions of the aneurysm necks harbored scattered tissue islands composed exclusively of inflammatory cells. At 4 and 8 weeks, all samples contiguous with the tissue along the parent arteries had translucent tissue present along the occluded segments of the aneurysm neck. The vast majority of endothelial cells were contiguous with the parent artery and had smooth muscle cells underlying them. Endothelial progenitor cells were not observed along the neck of any aneurysm. Aneurysm closure was noted only when complete or nearly complete endothelialization over the device struts was present. CONCLUSION The initial event following flow diversion treatment is adherence of clusters of inflammatory cells across the aneurysm neck. Endothelialization is relatively delayed and derived exclusively from cells in the adjacent parent artery.
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Ioannou K, Bennett M, Ignaszewski A, Tung S, Krahn A, Wilson-McManus J, Dai D, Assadian S, Hollander Z, McManus B, Park H, Woo K, Kang H, Ng R. Ensemble Analysis Using Blood-Based Biomarkers, Ambulatory Electrocardiography and Clinical Variables Predicts 30 Day Hospitalization in Patients With Heart Failure. Can J Cardiol 2013. [DOI: 10.1016/j.cjca.2013.07.320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
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