Publications by authors named "Afif Kraitem"

6 Publications

  • Page 1 of 1

Novel Oxygen Carrier Slows Infarct Growth in Large Vessel Occlusion Dog Model Based on Magnetic Resonance Imaging Analysis.

Stroke 2022 04 21;53(4):1363-1372. Epub 2022 Mar 21.

New England Center for Stroke Research, Department of Radiology (M.S., R.M.K., V.A., Z.V., A.K., J.K., C.R., M.J.G.), University of Massachusetts Medical School, Worcester.

Background: Tissue hypoxia plays a critical role in the events leading to cell death in ischemic stroke. Despite promising results in preclinical and small clinical pilot studies, inhaled oxygen supplementation has not translated to improved outcomes in large clinical trials. Moreover, clinical observations suggest that indiscriminate oxygen supplementation can adversely affect outcome, highlighting the need to develop novel approaches to selectively deliver oxygen to affected regions. This study tested the hypothesis that intravenous delivery of a novel oxygen carrier (Omniox-Ischemic Stroke [OMX-IS]), which selectively releases oxygen into severely ischemic tissue, could delay infarct progression in an established canine thromboembolic large vessel occlusion stroke model that replicates key dynamics of human infarct evolution.

Methods: After endovascular placement of an autologous clot into the middle cerebral artery, animals received OMX-IS treatment or placebo 45 to 60 minutes after stroke onset. Perfusion-weighted magnetic resonance imaging was performed to define infarct progression dynamics to stratify animals into fast versus slow stroke evolvers. Serial diffusion-weighted magnetic resonance imaging was performed for up to 5 hours to quantify infarct evolution. Histology was performed postmortem to confirm final infarct size.

Results: In fast evolvers, OMX-IS therapy substantially slowed infarct progression (by ≈1 hour, <0.0001) and reduced the final normalized infarct volume as compared to controls (0.99 versus 0.88, control versus OMX-IS drug, <0.0001). Among slow evolvers, OMX-IS treatment delayed infarct progression by approximately 45 minutes; however, this did not reach statistical significance (=0.09). The final normalized infarct volume also did not show a significant difference (0.93 versus 0.95, OMX-IS drug versus control, =0.34). Postmortem histologically determined infarct volumes showed excellent concordance with the magnetic resonance imaging defined ischemic lesion volume (bias: 1.33% [95% CI, -15% to 18%).

Conclusions: Intravenous delivery of a novel oxygen carrier is a promising approach to delay infarct progression after ischemic stroke, especially in treating patients with large vessel occlusion stroke who cannot undergo definitive reperfusion therapy within a timely fashion.
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http://dx.doi.org/10.1161/STROKEAHA.121.036896DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8960363PMC
April 2022

Biophysical targeting of high-risk cerebral aneurysms.

Bioeng Transl Med 2022 Jan 16;7(1):e10251. Epub 2021 Sep 16.

Department of Biomedical Engineering Technion Israel Institute of Technology Technion City, Haifa Israel.

Localized delivery of diagnostic/therapeutic agents to cerebral aneurysms, lesions in brain arteries, may offer a new treatment paradigm. Since aneurysm rupture leading to subarachnoid hemorrhage is a devastating medical emergency with high mortality, the ability to noninvasively diagnose high-risk aneurysms is of paramount importance. Moreover, treatment of unruptured aneurysms with invasive surgery or minimally invasive neurointerventional surgery poses relatively high risk and there is presently no medical treatment of aneurysms. Here, leveraging the endogenous biophysical properties of brain aneurysms, we develop particulate carriers designed to localize in aneurysm low-shear flows as well as to adhere to a diseased vessel wall, a known characteristic of high-risk aneurysms. We first show, in an in vitro model, flow guided targeting to aneurysms using micron-sized (2 μm) particles, that exhibited enhanced targeting (>7 folds) to the aneurysm cavity while smaller nanoparticles (200 nm) showed no preferable accumulation. We then functionalize the microparticles with glycoprotein VI (GPVI), the main platelet receptor for collagen under low-medium shear, and study their targeting in an in vitro reconstructed patient-specific aneurysm that contained a disrupted endothelium at the cavity. Results in this model showed that GPVI microparticles localize at the injured aneurysm an order of magnitude (>9 folds) more than control particles. Finally, effective targeting to aneurysm sites was also demonstrated in an in vivo rabbit aneurysm model with a disrupted endothelium. Altogether, the presented biophysical strategy for targeted delivery may offer new treatment opportunities for cerebral aneurysms.
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http://dx.doi.org/10.1002/btm2.10251DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8780020PMC
January 2022

Preventing Inadvertent Foreign Body Injection in Angiography.

Radiology 2021 05 9;299(2):460-467. Epub 2021 Mar 9.

From the Department of Neuroradiology, University Hospital RWTH Aachen, Neuroradiologie, Universitätsklinikum Aachen, Pauwelsstr 30, 52074 Aachen, Germany (O.N., T.S., M.W.); and New England Center for Stroke Research, University of Massachusetts Medical School, Worcester, Mass (A.K., R.A., M.J.G.).

Background Inadvertent injection of foreign material during angiography, particularly neuroangiography, should be avoided to reduce the risk of embolic complications. Woven gauze and cotton fabrics have been identified as sources of inadvertent foreign body embolization. Purpose To find the source of particles that contaminate injections on an angiography table and to identify measures for their reduction. Materials and Methods The number and size of particles on an angiographic supply table at a tertiary stroke center were analyzed by using the Coulter principle in September 2019. Seven conditions (saline directly drawn from its bag, from a small metal cup, from a small plastic cup, from a large plastic bowl, from a large plastic bowl with a guidewire and its sheath, from a large plastic bowl with a stack of woven gauze, and from a large plastic bowl with a large cotton towel) were tested at different time intervals (0, 30, and 60 minutes). Each container was filled with saline, and particle count was analyzed immediately after unpackaging, after rinsing with saline, and after introduction of foreign material; tests were used for statistical comparisons. Results Freshly unpacked basins can be contaminated with many submillimetric particles (range, 4.4-25.1 particles per milliliter on average, depending on basin). Cotton towels and woven gauze placed in rinsed basins resulted in a significant increase in particles (from 1.5 particles per milliliter ± 0.4 [standard deviation] to 64.4 particles per milliliter ± 4.1 and 257.1 particles per milliliter ± 11.6, respectively; < .001). Rinsing basins with saline significantly reduced the number of particles ( ≤ .03). Drawing saline directly from bags through intravenous lines yielded the lowest number of particles (0.1 particles per milliliter). Conclusion To decrease the risk for foreign body embolization, it is best to rinse all basins before use, draw saline and contrast agents directly from the respective bags and bottles through intravenous lines, and avoid cotton towels and woven gauze in basins and on the angiography table altogether whenever possible. © RSNA, 2021 See also the editorial by Nikolic in this issue.
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http://dx.doi.org/10.1148/radiol.2021200207DOI Listing
May 2021

High-resolution image-guided WEB aneurysm embolization by high-frequency optical coherence tomography.

J Neurointerv Surg 2021 Jul 28;13(7):669-673. Epub 2020 Sep 28.

Department of Radiology, New England Center for Stroke Research, University of Massachusetts Medical School, Worcester, Massachusetts, USA.

Background: High-frequency optical coherence tomography (HF-OCT) is an intra-vascular imaging technique capable of assessing device-vessel interactions at spatial resolution approaching 10 µm. We tested the hypothesis that adequately deployed Woven EndoBridge (WEB) devices as visualized by HF-OCT lead to higher aneurysm occlusion rates.

Methods: In a leporine model, elastase-induced aneurysms (n=24) were treated with the WEB device. HF-OCT and digital subtraction angiography (DSA) were performed following WEB deployment and repeated at 4, 8, and 12 weeks. Protrusion (0-present, 1-absent) and malapposition (0-malapposed, 1-neck apposition >50%) were binary coded. A device was considered 'adequately deployed' by HF-OCT and DSA if apposed and non-protruding. Aneurysm healing on DSA was reported using the 4-point WEB occlusion score: A or B grades were considered positive outcome. Neointimal coverage was quantified on HF-OCT images at 12 weeks and compared with scanning electron microscopy (SEM).

Results: Adequate deployment on HF-OCT correlated with positive outcome (P=0.007), but no statistically significant relationship was found between good outcome and adequate deployment on DSA (P=0.289). Absence of protrusion on HF-OCT correlated with a positive outcome (P=0.006); however, malapposition alone had no significant relationship (P=0.19). HF-OCT showed a strong correlation with SEM for the assessment of areas of neointimal tissue (R²=0.96; P<0.001). More neointimal coverage of 78%±32% was found on 'adequate deployment' cases versus 31%±24% for the 'inadequate deployment' cases (P=0.001).

Conclusion: HF-OCT visualizes features that can determine adequate device deployment to prognosticate early aneurysm occlusion following WEB implantation and can be used to longitudinally monitor aneurysm healing progression.
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http://dx.doi.org/10.1136/neurintsurg-2020-016447DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8205185PMC
July 2021

Biomechanics and hemodynamics of stent-retrievers.

J Cereb Blood Flow Metab 2020 12 19;40(12):2350-2365. Epub 2020 May 19.

New England Center for Stroke Research, Department of Radiology, University of Massachusetts Medical School, Worcester, MA, USA.

In 2015, multiple randomized clinical trials showed an unparalleled treatment benefit of stent-retriever thrombectomy as compared to standard medical therapy for the treatment of a large artery occlusion causing acute ischemic stroke. A short time later, the HERMES collaborators presented the patient-level pooled analysis of five randomized clinical trials, establishing class 1, level of evidence A for stent-retriever thrombectomy, in combination with intravenous thrombolysis when indicated to treat ischemic stroke. In the years following, evidence continues to mount for expanded use of this therapy for a broader category of patients. The enabling technology that changed the tide to support endovascular treatment of acute ischemic stroke is the stent-retriever. This review summarizes the history of intra-arterial treatment of stroke, introduces the biomechanics of embolus extraction with stent-retrievers, describes technical aspects of the intervention, provides a description of hemodynamic implications of stent-retriever embolectomy, and proposes future directions for a more comprehensive, multi-modal endovascular approach for the treatment of acute ischemic stroke.
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http://dx.doi.org/10.1177/0271678X20916002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7820689PMC
December 2020

Coronavirus Goes Viral: Quantifying the COVID-19 Misinformation Epidemic on Twitter.

Cureus 2020 Mar 13;12(3):e7255. Epub 2020 Mar 13.

Faculty of Medicine, American University of Beirut, Beirut, LBN.

Background Since the beginning of the coronavirus disease 2019 (COVID-19) epidemic, misinformation has been spreading uninhibited over traditional and social media at a rapid pace. We sought to analyze the magnitude of misinformation that is being spread on Twitter (Twitter, Inc., San Francisco, CA) regarding the coronavirus epidemic.  Materials and methods We conducted a search on Twitter using 14 different trending hashtags and keywords related to the COVID-19 epidemic. We then summarized and assessed individual tweets for misinformation in comparison to verified and peer-reviewed resources. Descriptive statistics were used to compare terms and hashtags, and to identify individual tweets and account characteristics. Results The study included 673 tweets. Most tweets were posted by informal individuals/groups (66%), and 129 (19.2%) belonged to verified Twitter accounts. The majority of included tweets contained serious content (91.2%); 548 tweets (81.4%) included genuine information pertaining to the COVID-19 epidemic. Around 70% of the tweets tackled medical/public health information, while the others were pertaining to sociopolitical and financial factors. In total, 153 tweets (24.8%) included misinformation, and 107 (17.4%) included unverifiable information regarding the COVID-19 epidemic. The rate of misinformation was higher among informal individual/group accounts (33.8%, p: <0.001). Tweets from unverified Twitter accounts contained more misinformation (31.0% vs 12.6% for verified accounts, p: <0.001). Tweets from healthcare/public health accounts had the lowest rate of unverifiable information (12.3%, p: 0.04). The number of likes and retweets per tweet was not associated with a difference in either false or unverifiable content. The keyword "COVID-19" had the lowest rate of misinformation and unverifiable information, while the keywords "#2019_ncov" and "Corona" were associated with the highest amount of misinformation and unverifiable content respectively. Conclusions Medical misinformation and unverifiable content pertaining to the global COVID-19 epidemic are being propagated at an alarming rate on social media. We provide an early quantification of the magnitude of misinformation spread and highlight the importance of early interventions in order to curb this phenomenon that endangers public safety at a time when awareness and appropriate preventive actions are paramount.
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http://dx.doi.org/10.7759/cureus.7255DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7152572PMC
March 2020
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