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748 citation(s) found for "Ma, Dan".

Predicting amyloid PET and tau PET stages with plasma biomarkers
Jack, Clifford R. , Wiste, Heather J. , Figdore, Daniel J. , Schwarz, Christopher G. , Lowe, Val J. , Ramanan, Vijay K. , Vemuri, Prashanthi , Mielke, Michelle M. , Knopman, David S. , Graff‐Radford, Jonathan , Kantarci, Kejal , Gunter, Jeffrey L. , Therneau, Terry M. , Petersen, Ronald C. , Knopman, David S. , Figdore, Dan J, Schwarz, Christopher G , Ramanan, Vijay K , Vemuri, Prashanthi , Mielke, Michelle M , Graff-Radford, Jonathan , Kantarci, Kejal , Cogswell, Petrice M , Jack, Clifford R , Figdore, Daniel J , Algeciras‐Schimnich, Alicia , Boeve, Bradley F. , Cogswell, Petrice M. , Senjem, Matthew L.

Brain | February 13, 2023 | Volume: 146 | Issue: 5 | Pages: 2029-2044

10.1093/brain/awad042 | PMID 36789483 Get It

Abstract Staging the severity of Alzheimer’s disease pathology using biomarkers is useful for therapeutic trials and clinical prognosis. Disease staging with amyloid and tau PET has face validity; however, this would be more practical with plasma biomarkers. Our objectives were, first, to examine approaches for staging amyloid and tau PET and, second, to examine prediction of amyloid and tau PET stages using plasma biomarkers. Participants (n = 1136) were enrolled in either the Mayo Clinic Study of Aging or the Alzheimer’s Disease Research Center; had a concurrent amyloid PET, tau PET and blood draw; and met clinical criteria for cognitively unimpaired (n = 864), mild cognitive impairment (n = 148) or Alzheimer’s clinical syndrome with dementia (n = 124). The latter two groups were combined into a cognitively impaired group (n = 272). We used multinomial regression models to estimate discrimination [concordance (C) statistics] among three amyloid PET stages (low, intermediate, high), four tau PET stages (Braak 0, 1–2, 3–4, 5–6) and a combined amyloid and tau PET stage (none/low versus intermediate/high severity) using plasma biomarkers as predictors separately within unimpaired and impaired individuals. Plasma analytes, p-tau181, Aβ1–42 and Aβ1–40 (analysed as the Aβ42/Aβ40 ratio), glial fibrillary acidic protein and neurofilament light chain were measured on the HD-X Simoa Quanterix platform. Plasma p-tau217 was also measured in a subset (n = 355) of cognitively unimpaired participants using the Lilly Meso Scale Discovery assay. Models with all Quanterix plasma analytes along with risk factors (age, sex and APOE) most often provided the best discrimination among amyloid PET stages (C = 0.78–0.82). Models with p-tau181 provided similar discrimination of tau PET stages to models with all four plasma analytes (C = 0.72–0.85 versus C = 0.73–0.86). Discriminating a PET proxy of intermediate/high from none/low Alzheimer’s disease neuropathological change with all four Quanterix plasma analytes was excellent but not better than p-tau181 only (C = 0.88 versus 0.87 for unimpaired and C = 0.91 versus 0.90 for impaired). Lilly p-tau217 outperformed the Quanterix p-tau181 assay for discriminating high versus intermediate amyloid (C = 0.85 versus 0.74) but did not improve over a model with all Quanterix plasma analytes and risk factors (C = 0.85 versus 0.83). Plasma analytes along with risk factors can discriminate between amyloid and tau PET stages and between a PET surrogate for intermediate/high versus none/low neuropathological change with accuracy in the acceptable to excellent range. Combinations of plasma analytes are better than single analytes for many staging predictions with the exception that Quanterix p-tau181 alone usually performed equivalently to combinations of Quanterix analytes for tau PET discrimination.
Subcutaneous implantable cardioverter‐defibrillator noise following left ventricular assist device implantation
Khetarpal, Banveet Kaur , Javaid, Awad , Lee, Justin Z. , Mulpuru, Siva K. , Sorajja, Dan , Cha, Yong‐Mei , Mulpuru, Siva K , Kusumoto, Fred , Srivathsan, Komandoor

Journal of Arrhythmia | February 13, 2023 | Volume: 39 | Issue: 2 | Pages: 198-206

10.1002/joa3.12826 | PMID 37021015 Get It

AbstractBackgroundThe incidence and impact of noise in a subcutaneous implantable cardioverter defibrillator (S‐ICD) after left ventricular assist device (LVAD) implantation is not well established.MethodsWe performed a retrospective study of patients implanted with LVAD and with a pre‐existing S‐ICD between January 2005 and December 2020 at the three Mayo Clinic centers (Minnesota, Arizona, and Florida).ResultsOf the 908 LVAD patients, a pre‐existing S‐ICD was present in 9 patients (mean age 49.1 ± 13.7 years, 66.7% males), 100% with Boston Scientific third‐generation EMBLEM MRI S‐ICD, 11% with HeartMate II (HM II), 44% with HeartMate 3 (HM 3), and 44% with HeartWare (HW) LVAD. The incidence of noise from LVAD‐related electromagnetic interference (EMI) was 33% and was only seen with HM 3 LVAD. Multiple measures attempted to resolve noise, including using alternative S‐ICD sensing vector, adjusting S‐ICD time zone, and increasing LVAD pump speed, were unsuccessful, necessitating S‐ICD device therapies to be turned off permanently.ConclusionsThe incidence of LVAD‐related S‐ICD noise is high in patients with concomitant LVAD and S‐ICD with significant impact on device function. As conservative management failed to resolve the EMI, the S‐ICDs had to be programmed off to avoid inappropriate shocks. This study highlights the importance of awareness of LVAD‐SICD device interference and the need to improve S‐ICD detection algorithms to eliminate noise.
P860 The Costs of Inflammatory Bowel Diseases in High-Income Settings
Odes, Shmuel , Bernstein, Çharles N. , Ďuricová, Dana , Ahn, Hanse , Annese, V, Park, K, H, K H Konstantinos, Høivik, Marte Lie , Bemelman, Willem A. , Moum, B, Hart, Adam , Pierik, M, Ng, S S S, Munkholm, Pia, Burisch, Johan , Zhao, Mirabella , Cruz, Peter De , Vermeire, Séverine , Bernstein, Charles Noah , Kaplan, Gilaad G. , Greenberg, Dan , Melberg, Hans Olav , Watanabe, Masatoshi , Ahn, H S, Targownik, Laura E. , Pittet, Valerie E. H. , Krznarić, Željko , Chaparro, María , Loftus, Edward V. , Lakatos, Péter L. , Gisbert, Javier P. , Moum, Bjørn Allan , Gearry, Richard B. , Kappelman, Michael D. , Hart, A, Pierik, M, Andrews, Jane Mary , D'Incà, Renata

Journal of Crohn's and Colitis | January 30, 2023 | Volume: 17 | Issue: Supplement_1 | Pages: i983-i983

10.1093/ecco-jcc/jjac190.0990 Get It

Abstract Background Crohn’s disease (CD) and ulcerative colitis (UC), together known as inflammatory bowel diseases (IBD), affect approximately seven million people globally. The continuous rise in IBD prevalence and the aging of populations will inevitably lead to an increasing use of health care resources. In parallel with these trends, continuing innovations in IBD therapeutics, diagnostics, and preventatives are creating more options for IBD patients seeking to reduce their disease burden. These trends pose an imminent burden on health care systems and require that we identify modifiable cost drivers in IBD care and develop strategies for delivering equitable and affordable care for all patients. Methods This Lancet Gastroenterology & Hepatology Commission, consisting of a diverse faculty of health care professionals with expertise in the field of IBD and health economists, was formed to deliver an extensive summary of the literature and discuss key topics on the costs and cost-effectiveness of treating IBD in the present, and how this is likely to look in the future. Furthermore, it offers suggestions for how to deliver affordable IBD care in the coming years. The report’s focus was on high-income countries in Europe, North America, Australia and New Zealand, and Asia. Results The Commission drew together a wide range of expertise to discuss the current costs of IBD care, the drivers of increasing costs, as well as how to deliver affordable care for IBD in the future. The key conclusions are that (i) increases in health care costs must be evaluated against improved disease control and reductions in indirect costs, and (ii) that overarching systems for data interoperability, registries, and big data approaches must be established for continuous assessment of effectiveness, costs, and cost-effectiveness of care. International collaborations should be sought in order to evaluate novel models of care (such as value-based health care, including integrated health care and participatory health care models), as well as to improve the education and training of clinicians, patients, and policymakers. Measures to reduce the costs of IBD care are summarised in Table 1. Conclusion Increases in health care costs must be evaluated against improved disease control and reductions in indirect costs. Evaluations should be systematically aligned between countries and regions. Detailed analysis of the current epidemiology and the likely effects of changing IBD management on disease course and socioeconomic outcomes is essential; and will become even more imperative in the era of precision medicine, where complex biotechnologies will require expensive analyses, highly skilled personnel, and drug development for what may sometimes be relatively small patient groups.
Human VH-based chimeric antigen receptor T cells targeting glypican 3 eliminate tumors in preclinical models of HCC
Kolluri, Aarti , Li, Dan , Li, Nan , Duan, Zhijian , Roberts, Lewis R. , Ho, Mitchell , Roberts, Lewis R

Hepatology Communications | January 24, 2023 | Volume: 7 | Issue: 2 | Pages: e0022-e0022

10.1097/hc9.0000000000000022 | PMID 36691969 Get It

Background and Aims: Efficacy of chimeric antigen receptor (CAR) T cells for treating solid tumors, including HCC, remains a challenge. Nanobodies are emerging building blocks of CAR T cells due to their small size and high expression. Membrane proximal sites have been shown as attractive epitopes of CAR T cells. However, current CAR formats are not tailored toward nanobodies or targeting membrane distal epitopes. Approach and Results: Using hYP7 Fv (membrane proximal) and HN3 VH nanobody (membrane distal) as GPC3 targeting elements, we sought to determine how hinges and transmembrane portions of varying structures and sizes affect CAR T-cell function. We generated multiple permutations of CAR T cells containing CD8, CD28, IgG4, and Fc domains. We show that engineered HN3 CAR T cells can be improved by 2 independent, synergistic changes in the hinge and transmembrane domains. The T cells expressing the HN3 CAR which contains the hinge region of IgG4 and the CD28 transmembrane domain (HN3-IgG4H-CD28TM) exhibited high cytotoxic activity and caused complete HCC tumor eradication in immunodeficient mice. HN3-IgG4H-CD28TM CAR T cells were enriched for cytotoxic-memory CD8+ T cells and NFAT signals, and reduced β catenin levels in HCC cells. Conclusion: Our findings indicate that altering the hinge and transmembrane domains of a nanobody-based CAR targeting a distal GPC3 epitope, in contrast to a membrane proximal epitope, lead to robust T-cell signaling and induce swift and durable eradication of HCC tumors.
Racial Differences in Germline Genetic Testing for Prostate Cancer: A Systematic Review
Briggs, Logan , Steele, Grant , Qian, Zhiyu , Subbanna, Sara, Alkhatib, Khalid Y. , Labban, Muhieddine , Langbein, Bjoern, Nguyen, David‐Dan , Cellini, Jacqueline , Kilbridge, Kerry L. , Kibel, Adam S. , Rana, Huma Q. , Briggs, Logan G , Steele, Grant L , Trinh, Quoc-Dien , Rana, Huma Q , Cole, Alexander P , Trinh, Quoc‐Dien

JCO Oncology Practice | January 17, 2023 | Volume: 19 | Issue: 5 | Pages: e784-e793

10.1200/op.22.00634 | PMID 36649495 Get It

PURPOSE: Testing for pathogenic variants can aid in oncologic risk stratification and identification of targeted therapies. Despite known disparities in access to prostate cancer (PCa) care, little has been written about access to germline genetic testing (GGT) for Black men and other historically marginalized populations. This systematic review sought to delineate racial/ethnic disparities in GGT for PCa. METHODS: This systematic review identified articles published from January 1996 through May 2021 in PubMed, Web of Science, and Embase. We included studies that reported rates of GGT in men with PCa in the United States by race/ethnicity as reflective of routine clinical care or research. A narrative synthesis was performed. RESULTS: Of 4,309 unique records, 91 studies examining 50 unique study populations met inclusion criteria. Of these, four populations included men who received GGT through routine clinical care, accounting for 4,415 men (72.6% White and 7.2% Black). The other 46 populations included men who received GGT as part of a research study, accounting for 30,824 men (64.3% White and 21.6% Black). Of these 46 research populations, 19 used targeted methods to increase recruitment from a specific demographic. CONCLUSION: Most studies that report GGT rates by race/ethnicity are in research settings. Many of these studies used targeted recruitment methods and subsequently have a greater proportion of Black men than clinical and US population–based studies. Other historically marginalized populations are not well represented. There remains a knowledge gap regarding the extent of racial disparities in the use of GGT, particularly in the clinical setting.
Changes in Elbow Stress and Ball Velocity During Reduced Effort Pitching: A Marker-Based Motion Capture Analysis
Fiegen, Anthony P., Nezlek, Stuart, Loushin, Stacy R. , Christoffer, Dan, Verhoeven, Martijn, Nezlek, Stuart P, Fiegen, Anthony P. , Kaufman, Kenton R. , Camp, Christopher L.

The American Journal of Sports Medicine | January 10, 2023 | Volume: 51 | Issue: 3 | Pages: 779-785

10.1177/03635465221144020 | PMID 36625428 Get It

Background: Baseball pitchers often participate in throwing programs that involve throwing at reduced effort levels to gradually increase the amount of stress experienced across the elbow. It is currently unknown how reduced effort pitching compares with maximum effort with respect to elbow stress and ball velocity. Purpose/Hypothesis: The purpose was to determine the correlation between elbow stress and ball velocity with reduced effort pitching. We hypothesized that decreased perceived effort would disproportionately correlate with elbow stress and ball velocity. Study Design: Descriptive laboratory study. Methods: Ten healthy male high school baseball pitchers threw 5 pitches from a regulation pitching mound at 3 effort levels: maximum effort, 75% effort, and 50% effort. Elbow stress, specifically elbow varus torque, was calculated for all pitches using a validated marker-based 3-dimensional motion capture system. Ball velocity was measured using a Doppler radar gun. Intrathrower variability was calculated for each effort level. Results: Elbow stress and ball velocity decreased with reduced effort throws ( P < .001 and P = .003, respectively). However, the reductions in elbow stress and ball velocity were not proportional. At 75% effort throws, elbow stress measured 81% (intraclass correlation coefficient [ICC], 0.95), and ball velocity measured 90% (ICC, 0.80) of maximum, respectively. At 50% effort throws, elbow stress measured 75% (ICC, 0.93), and ball velocity measured 85% (ICC, 0.87) of maximum. Intrathrower reliability was excellent for elbow stress and ball velocity, with all ICCs ≥0.80. Conclusion: Pitching at a reduced effort level resulted in decreased elbow stress and ball velocity. However, for every 25% reduction in perceived effort, elbow stress decreased by a mean 13%, and ball velocity decreased 7.5%. When baseball pitchers attempt to throw at a reduced effort of maximum, throwing metrics do not decrease proportionately. Clinical Relevance: While pitching at a reduced effort of maximum decreases elbow stress and ball velocity, the decrease is not proportional, subjecting the elbow to more stress than intended. This has significant clinical importance to pitchers, coaches, and medical professionals in the setting of injury prevention and return to sports.
Factors influencing post-surgical survival in degenerative mitral regurgitation
Butcher, Steele C. , Essayagh, Benjamin , Benfari, Giovanni , Antoine, Clémence , Roussel, Jean‐Christian , Wijngaarden, Aniek Van, Tribouilloy, Christophe , Ruşinaru, Dan, Topilsky, Yan , Michelena, Héctor I. , Delgado, Victoria , Enriquez‐Sarano, Maurice , Topilsky, Yan , Benfari, Giovanni , Roussel, Jean-Christian , Tribouilloy, Christophe , Hochstadt, Aviram , Michelena, Hector I , Enriquez-Sarano, Maurice , Delgado, Victoria , Topilsky, Yan , Essayagh, Benjamin , Butcher, Steele C , Steyerberg, Ewout W. , Grigioni, Francesco , Tourneau, Thierry Le , Marsan, Nina Ajmone , Bax, Jeroen J.

European Heart Journal | January 4, 2023 | Volume: 44 | Issue: 10 | Pages: 871-881

10.1093/eurheartj/ehad004 | PMID 36702625 Get It

Abstract Aims Indications for surgery in patients with degenerative mitral regurgitation (DMR) are increasingly liberal in all clinical guidelines but the role of secondary outcome determinants (left atrial volume index ≥60 mL/m2, atrial fibrillation, pulmonary artery systolic pressure ≥50 mmHg and moderate to severe tricuspid regurgitation) and their impact on post-operative outcome remain disputed. Whether these secondary outcome markers are just reflective of the DMR severity or intrinsically affect survival after DMR surgery is uncertain and may have critical importance in the management of patients with DMR. To address these gaps of knowledge the present study gathered a large cohort of patients with quantified DMR, accounted for the number of secondary outcome markers and examined their independent impact on survival after surgical correction of the DMR. Methods and results The Mitral Regurgitation International DAtabase-Quantitative registry includes patients with isolated DMR from centres across North America, Europe, and the Middle East. Patient enrolment extended from January 2003 to January 2020. All patients undergoing mitral valve surgery within 1 year of registry enrolment were selected. A total of 2276 patients [65 (55–73) years, 32% male] across five centres met study eligibility criteria. Over a median follow-up of 5.6 (3.6 to 8.7) years, 278 patients (12.2%) died. In a comprehensive multivariable Cox regression model adjusted for age, EuroSCORE II, symptoms, left ventricular ejection fraction (LVEF), left ventricular end-systolic diameter (LV ESD) and DMR severity, the number of secondary outcome determinants was independently associated with post-operative all-cause mortality, with adjusted hazard ratios of 1.56 [95% confidence interval (CI): 1.11–2.20, P = 0.011], 1.78 (95% CI: 1.23–2.58, P = 0.002) and 2.58 (95% CI: 1.73–3.83, P &lt; 0.0001) for patients with one, two, and three or four secondary outcome determinants, respectively. A model incorporating the number of secondary outcome determinants demonstrated a higher C-index and was significantly more concordant with post-operative mortality than models incorporating traditional Class I indications alone [the presence of symptoms (P = 0.0003), or LVEF ≤60% (P = 0.006), or LV ESD ≥40 mm (P = 0.014)], while there was no significant difference in concordance observed compared with a model that incorporated the number of Class I indications for surgery combined (P = 0.71). Conclusion In this large cohort of patients treated surgically for DMR, the presence and number of secondary outcome determinants was independently associated with post-surgical survival and demonstrated better outcome discrimination than traditional Class I indications for surgery. Randomised controlled trials are needed to determine if patients with severe DMR who demonstrate a cardiac phenotype with an increasing number of secondary outcome determinants would benefit from earlier surgery.
MHC class I expression on tumor targets inhibits natural killer cell-mediated cytotoxicity without interfering with target recognition
Schoon, Renee A., Leibson, Paul J., Kaufman, Dan S.

The Journal of Immunology | December 31, 2022 | Volume: 150 | Issue: 4 | Pages: 1429-1436

10.4049/jimmunol.150.4.1429 Get It

Abstract NK cell-mediated killing is inversely proportional to the amount of MHC class I expression on certain tumor targets. Two hypotheses have been proposed to explain why class I-bearing targets are more resistant to NK cell-mediated lysis: 1) the presence of class I prevents NK cell recognition of a triggering molecule on the target cell surface, or 2) class I recognition transmits a separate inhibitory signal to the NK cell. To differentiate between these potential mechanisms, we have used cloned human CD16+/CD3- NK cells, the class I-deficient cell line C1R, and C1R cells expressing high levels of transfected HLA class I gene products. If class I expression blocks NK cell recognition of the targets, then proximal cell signaling events such as phospholipase C-mediated hydrolysis of membrane phosphoinositides should be decreased in the NK cells interacting with the class I transfectants. However, we found that increases in the level of target cell class I expressions did not decrease phosphoinositide turnover or calcium signaling in NK cells. We also examined the effect of treating HLA-transfected C1R cells with mAb specific for the transfected MHC class I gene product. If class I expression has a negative regulatory influence on NK cell activation, then treating the targets with anti-HLA mAb should block the transmission of this negative signal. Consistent with this notion, addition of anti-HLA mAb (either whole Ig or F(ab’)2 fragments) led to increased lysis of the class I-transfected targets. In contrast, addition of isotype-matched mAb specific for other cell surface markers did not alter sensitivity to lysis. All of these results suggest that MHC class I expression on target cells can initiate inhibitory signals in NK cells without blocking access to target structures.
The MIDA-Q Mortality Risk Score: A Quantitative Prognostic Tool for the Mitral Valve Prolapse Spectrum
Essayagh, Benjamin , Benfari, Giovanni , Antoine, Clémence , Grigioni, Francesco , Tourneau, Thierry Le , Roussel, Jean‐Christian , Bax, Jeroen J. , Delgado, Victoria , Wijngaarden, Aniek Van, Tribouilloy, Christophe , Ruşinaru, Dan, Topilsky, Yan , Thapa, Prabin , Topilsky, Yan , Le Tourneau, Thierry , Marsan, Nina Ajmone , Tribouilloy, Christophe , Hochstadt, Aviram , Topilsky, Yan , Michelena, Hector I , Enriquez-Sarano, Maurice , Delgado, Victoria , Bax, Jeroen J , Benfari, Giovanni , Topilsky, Yan , Essayagh, Benjamin , Grigioni, Francesco , Marsan, Nina Ajmone , Michelena, Héctor I. , Enriquez‐Sarano, Maurice

Circulation | December 27, 2022 | Volume: 147 | Issue: 10 | Pages: 798-811

10.1161/circulationaha.122.062612 | PMID 36573420 Get It

Background: Mitral valve prolapse (MVP) is responsible for a considerable disease burden but is widely heterogeneous. The lack of a comprehensive prognostic instrument covering the entire MVP spectrum, encompassing the quantified consequent degenerative mitral regurgitation (DMR), hinders clinical management and therapeutic trials. Methods: The new Mitral Regurgitation International Database Quantitative (MIDA-Q) registry enrolled 8187 consecutive patients (ages 63±16 years, 47% women, follow-up 5.5±3.3 years) first diagnosed with isolated MVP, without or with DMR quantified prospectively (measuring effective regurgitant orifice [ERO] and regurgitant volume) in routine practice of 5 tertiary care centers from North America, Europe, and the Middle East. The MIDA-Q score ranges from 0 to 15 by accumulating guideline-based risk factors and DMR severity. Long-term survival under medical management was the primary outcome end point. Results: MVP was associated with DMR absent/mild (ERO <20 mm 2 ) in 50%, moderate (ERO 20–40 mm 2 ) in 25%, and severe or higher (ERO ≥40 mm 2 ) in 25%, with mean ERO 24±24 mm 2 , regurgitant volume 37±35 mL. Median MIDA-Q score was 4 with a wide distribution (10%–90% range, 0–9). MIDA-Q score was higher in patients with EuroScore II ≥1% versus <1% (median, 7 versus 3; P < 0.0001) but with wide overlap (10%–90% range, 4–11 versus 0–7) and mediocre correlation ( R 2 0.18). Five-year survival under medical management was strongly associated with MIDA-Q score, 97±1% with score 0, 95±1% with score 1 to 2, 82±1% with score 3 to 4, 67±1% with score 5 to 6, 60±1% with score 7 to 8, 44±1% with score 9 to 10, 35±1% with score 11 to 12, and 5±4% with MIDA-Q score ≥13, with hazard ratio 1.31 [1.29–1.33] per 1-point increment. Excess mortality with higher MIDA-Q scores persisted after adjustment for age, sex, and EuroScore II (adjusted hazard ratio, 1.13 [1.11–1.15] per 1-point increment). Subgroup analysis showed persistent association of MIDA-Q score with mortality in all possible subsets, in particular, with EuroScore II<1% (hazard ratio, 1.08 [1.02–1.14]) or ≥1% (hazard ratio, 1.11 [1.08–1.13]) and with no/mild DMR (hazard ratio, 1.14 [1.10–1.19]) or moderate/severe DMR (hazard ratio, 1.13 [1.10–1.16], all per 1-point increment with P <0.0001). Nested-model and bootstrapping analyses demonstrated incremental prognostic power of MIDA-Q score (all P <0.0001). Conclusions: This large, international cohort of isolated MVP, with prospective DMR quantification in routine practice, demonstrates the wide range of risk factor accumulation and considerable heterogeneity of outcomes after MVP diagnosis. The MIDA-Q score is strongly, independently, and incrementally associated with long-term survival after MVP diagnosis, irrespective of presentation, and is therefore a crucial prognostic instrument for risk stratification, clinical trials, and management of patients diagnosed with all forms of MVP.
Benchtop proof of concept and comparison of iron- and magnesium-based bioresorbable flow diverters
Bilgin, Cem , Vercnocke, Andrew J. , Carlson, Kent, Kadirvel, Ramanathan , Griebel, Adam J. , Schaffer, Jeremy E. , Dragomir‐Daescu, Dan , Kallmes, David F. , Oliver, Alexander A , Dragomir-Daescu, Dan, Guillory, Roger J.

Journal of Neurosurgery | December 23, 2022 | Volume: 139 | Issue: 1 | Pages: 150-156

10.3171/2022.11.jns222213 | PMID 36681964 Get It

OBJECTIVE Bioresorbable flow diverters (BRFDs) could significantly improve the performance of next-generation flow diverter technology. In the current work, magnesium and iron alloy BRFDs were prototyped and compared in terms of porosity/pore density, radial strength, flow diversion functionality, and resorption kinetics to offer insights into selecting the best available bioresorbable metal candidate for the BRFD application. METHODS BRFDs were constructed with braided wires made from alloys of magnesium (MgBRFD) or iron (FeBRFD). Pore density and crush resistance force were measured using established methods. BRFDs were deployed in silicone aneurysm models attached to flow loops to investigate flow diversion functionality and resorption kinetics in a simulated physiological environment. RESULTS The FeBRFD exhibited higher pore density (9.9 vs 4.3 pores/mm2) and crush resistance force (0.69 ± 0.05 vs 0.53 ± 0.05 N/cm, p = 0.0765, n = 3 per group) than the MgBRFD, although both crush resistances were within the range previously reported for FDA-approved flow diverters. The FeBRFD demonstrated greater flow diversion functionality than the MgBRFD, with significantly higher values of established flow diversion metrics (mean transit time 159.6 ± 11.9 vs 110.9 ± 1.6, p = 0.015; inverse washout slope 192.5 ± 9.0 vs 116.5 ± 1.5, p = 0.001; n = 3 per group; both metrics expressed as a percentage of the control condition). Last, the FeBRFD was able to maintain its braided structure for > 12 weeks, whereas the MgBRFD was almost completely resorbed after 5 weeks. CONCLUSIONS The results of this study demonstrated the ability to manufacture BRFDs with magnesium and iron alloys. The data suggest that the iron alloy is the superior material candidate for the BRFD application due to its higher mechanical strength and lower resorption rate relative to the magnesium alloy.