Browsing by Author "Lee, Tiffany"

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    Cerebrovascular pathology and neurovascular coupling impairment in aged‐mouse model of Alzheimer’s disease
    (Wiley, 2025-01-09) Promkan, Moltira; Phikulthong, Kamonchat; Kimseng, Rungruedee; Pauss, Kate; Lee, Tiffany; Weekman, Erica M.; Nelson, Peter T.; Wilcock, Donna M.; Sompol, Pradoldej; Neurology, School of Medicine
    Background: Vascular pathology profoundly comorbid with AD pathology could worsen disease progression and reduce treatment efficacy. Knowledge of small vessels and cerebrovascular function in AD mouse models is limited. Investigating vascular related aspects for preclinical AD studies is essential for biomarker development and treatment trials. Therefore, we aim to characterize cerebrovascular amyloid angiopathy (CAA), vascular degeneration, and cerebrovascular function in an aged Tg2576 mouse model of AD. Method: WT and Tg2576 (∼ 2 years of age) were housed in a reversed light cycle room. Cranial window surgery and cranial window installation were performed. After 3 weeks of recovery, the animals were acclimated to an intravital multiphoton imaging platform. To visualize beta‐amyloid in the brain, Methoxy‐X04 (10mg/kg) was injected the day before the imaging. Cerebrovasculature was visualized by intravascular retro‐orbital injection of rhodamine‐dextran (5% V/W in saline). This procedure was done while the animals were under anesthesia and securely head‐fixed prior to the imaging. Z‐stack imaging was performed, and vascular structure was analyzed by using FIJI or ImageJ. Neurovascular coupling was performed to investigate vascular function in awake mice. While imaging penetrating arteriole, air‐puff stimulation of contralateral whiskers was conducted and increased vascular diameter is used as an indicator of hyperemic neurovascular function. Result: Investigation of cerebrovascular pathology including CAA, vascular straightness, and vascular blebbing are ongoing. During whisker stimulation, vascular diameter was relatively reduced in Tg2576 compared to WT control mice. Conclusion: Aged Tg2576 exhibits comorbidity of amyloid plaques, cerebral amyloid angiopathy, small vessel pathology and cerebrovascular dysfunction similar to human brain. This aged Tg2576 could be used as a preclinical translational mixed vascular/AD model.
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    Outcomes of shared institutional review board compared with multiple individual site institutional review board models in a multisite clinical trial
    (Elsevier, 2023) Martin, Samantha L.; Allman, Phillip H.; Dugoff, Lorraine; Sibai, Baha; Lynch, Stephanie; Ferrara, Jennifer; Aagaard, Kjersti; Zornes, Christina; Wilson, Jennifer L.; Gibson, Marie; Adams, Molly; Longo, Sherri A.; Staples, Amy; Saade, George; Beche, Imene; Carter, Ebony B.; Owens, Michelle Y.; Simhan, Hyagriv; Frey, Heather A.; Khan, Shama; Palatnik, Anna; August, Phyllis; Irby, Les'Shon; Lee, Tiffany; Lee, Christine; Schum, Paula; Chan-Akeley, Rosalyn; Duhon, Catera; Rincon, Monica; Gibson, Kelly; Wiegand, Samantha; Eastham, Donna; Oparil, Suzanne; Szychowski, Jeff M.; Tita, Alan; Chronic Hypertension and Pregnancy Consortium; Obstetrics and Gynecology, School of Medicine
    Background: Institutional review boards play a crucial role in initiating clinical trials. Although many multicenter clinical trials use an individual institutional review board model, where each institution uses their local institutional review board, it is unknown if a shared (single institutional review board) model would reduce the time required to approve a standard institutional review board protocol. Objective: This study aimed to compare processing times and other processing characteristics between sites using a single institutional review board model and those using their individual site institutional review board model in a multicenter clinical trial. Study design: This was a retrospective study of sites in an open-label, multicenter randomized control trial from 2014 to 2021. Participating sites in the multicenter Chronic Hypertension and Pregnancy trial were asked to complete a survey collecting data describing their institutional review board approval process. Results: A total of 45 sites participated in the survey (7 used a shared institutional review board model and 38 used their individual institutional review board model). Most sites (86%) using the shared institutional review board model did not require a full-board institutional review board meeting before protocol approval, compared with 1 site (3%) using the individual institutional review board model (P<.001). Median total approval times (41 vs 56 days; P=.42), numbers of submission rounds (1 vs 2; P=.09), and numbers of institutional review board stipulations (1 vs 4; P=.12) were lower for the group using the shared institutional review board model than those using the individual site institutional review board model; however, these differences were not statistically significant. Conclusion: The findings supported the hypothesis that the shared institutional review board model for multicenter studies may be more efficient in terms of cumulative time and effort required to obtain approval of an institutional review board protocol than the individual institutional review board model. Given that these data have important implications for multicenter clinical trials, future research should evaluate these findings using larger or multiple multicenter trials.
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    Selective sex‐based differences in the association between angiogenic and Alzheimer’s Disease biomarkers in a preliminary cohort of rrAD participants
    (Wiley, 2025-01-09) Lutshumba, Jenny; Wilcock, Donna M.; Lee, Tiffany; Zhu, David C.; Scheel, Norman; German, Dwight C.; Zhang, Rong; Trout, Amanda; Stowe, Ann M.; Neurology, School of Medicine
    Background: Vascular contributions to cognitive impairment and dementia (VCID) and Alzheimer’s disease (AD) are the two most common forms of dementia, with overlapping risk factors including cardiovascular risk factors such as hypertension and dyslipidemia. The etiology of both VCID and AD shows sex‐based differences, as well as sex‐based differences in cardiovascular risk factors. However, how sex differences influence AD and angiogenic biomarkers in older adults who have high cardiovascular risk factors is not known. Method: AD and angiogenic biomarkers for VCID were measured from the plasma of a subgroup (n=96) of participants from the ‘risk reduction for Alzheimer’s disease’ (rrAD) two‐year clinical trial (NCT02913664; completed Jan. 2022; n=513 total participants). rrAD participants had a family history of dementia or subjective memory complaints, hypertension, and dyslipidemia. The subgroup in the study included 31 males and 65 females (aged: 71‐85). Baseline values for AD biomarkers: Total tau, pTau181, Aβ40, and Aβ42, angiogenic biomarkers: Tie‐2, VEGF‐A, VEGF‐C, VEGFR1, and VCID biomarkers: bFGF, VEGF‐D, PlGF were analyzed using Meso Scale Discovery (MSD). Nonparametric analysis evaluated the sex differences in biomarkers, linear regression evaluated the relationship between AD biomarkers and angiogenic biomarkers in both sexes. Result: We found sex‐based differences in AD biomarkers such that females had a higher expression in Total tau and Total tau/Aβ42 (p=0.0021, p=0.0003, respectively) while pTau181 was higher in males (p=0.0216). pTau181/ Aβ42 and Aβ42/40 ratios showed no sex differences, nor did baseline angiogenic biomarkers. There was, however, a selective sex difference in the association between angiogenic and AD biomarkers. In females, Total tau is associated with VEGF‐D (R2= 0.0746, p=0.0277), and Tau/Aβ42 is associated with VEGF‐A and VEGFR‐1(R2= 0.0747, p=0.0275; R2= 0.0973, p=0.0114, respectively). In males, pTau181 and pTau181/Aβ42 are associated with VEGF‐D (R2= 0.2637, p=0.0031; R2= 0.1799, p=0.0174, respectively), Aβ42/Aβ40 is associated with VEGF‐C (R2= 0.1491, p=0.0319), and Tau/Aβ42 is associated with bFGF (R2= 0.1458, p=0.0340). Conclusion: There is a selective sex‐based difference in plasma AD biomarkers and their association with angiogenic biomarkers in this preliminary cohort of older adults with high risks of developing Alzheimer’s disease and related dementias.
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    The Effect of Sex‐Differences on the Relationship Between White Matter Hyperintensity, Cerebrovascular Reactivity, and Fluid Biomarkers
    (Wiley, 2025-01-09) Bahrani, Ahmed A.; Jiang, Yang; Powell, David K.; Katsumata, Yuriko; Nahvi, Azadeh; Lee, Tiffany; Gold, Brian T.; Goldstein, Larry B.; Wilcock, Donna M.; Jicha, Gregory A.; Nelson, Peter T.; Norris, Christopher M.; Neurology, School of Medicine
    Background: Alzheimer’s disease (AD) and vascular cognitive impairment and dementia (VCID) are the predominant types of dementia in older adults, associated with memory loss and cognitive deficits. White matter hyperintensities (WMH) are linked to both AD and VCID. Astrocytes play a crucial role in WM integrity, encompassing functions like neuroinflammation, oxidative stress, and Aβ clearance. Poorly reactive astrocytes could lead to implications, like WMH or vascular damage. This study aims to explore sex‐differences effect on the correlation between fluid biomarkers, WMH, and cerebrovascular reactivity (CVR). Method: Twenty‐seven participants (mean age 76.8±6.4 years, Female=15) preliminary data were collected from UK‐ADRC/MarkVCID cohorts. A correlation test was employed to examine sex‐differences based on the correlation of fluid inflammatory (GFAP, IL6, IL8, IL10), angiogenic (TDP‐43, and PlGF) biomarkers, and Aβ40 and 42, to global and regional CVR and WMH. Results: We observed several sex‐differences: the female group showed a significant correlation between WMH at occipital lobe and IL6 (P=0.031), IL10 (P=0.036), and GFAP (P=0.037), while male group only showed a significant correlation between Aβ42 and WMH at the occipital lobe (P=0.039). CVR data of the female group exhibited a correlation at the parietal lobe (right‐hemisphere) and IL8 (P=0.037) and Aβ40 (P=0.038) and between Aβ40 and CVR temporal lobe (right‐hemisphere, P=0.021). The male group showed a significant correlation between IL6 and CVR at the occipital lobe (left‐hemisphere, P=0.012. Generally, the female group showed higher mean values for all biomarkers except for IL10 and PIGF, but only significant at GFAP and TDP43. Additionally, the correlation test adjusted for age and sex showed that TDP‐43 had a significant correlation with WMH in the temporal (P=0.041), occipital (P=0.024), and parietal (P=0.024) lobes, while GFAP displayed a significant correlation only with WMH in the frontal lobe (P=0.013). Conclusions: Despite the small sample size, which warrants expansion in future studies, we observed interesting findings of sex‐differences in specific brain regions in relation to fluid biomarkers. These biomarkers may arise, in part, from reactive astrocytes, commonly found near many brain lesions, including WM pathology. Further studies are needed to gain deeper insight into astrocyte activities in diseases associated with WMH and CVR, like AD.