Publications by authors named "Vaishnavi Rao"

9 Publications

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Validation of the Global Limb Anatomic Staging System in first-time lower extremity revascularization.

J Vasc Surg 2020 Oct 20. Epub 2020 Oct 20.

Division of Vascular and Endovascular Surgery, Department of Surgery, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Mass. Electronic address:

Objective: The Global Limb Anatomic Staging System (GLASS) was developed as a new anatomic classification scheme to grade the severity of chronic limb threatening ischemia. We evaluated the ability of this anatomic grading system to determine major adverse limb events after lower extremity revascularization.

Methods: We performed a single-institutional retrospective review of 1060 consecutive patients who had undergone 1180 first-time open or endovascular revascularization procedures for chronic limb threatening ischemia from 2005 to 2014. Using the review of angiographic images, the limbs were classified as GLASS stage 1, 2, or 3. The primary composite outcome was reintervention, major amputation (below- or above-the-knee amputation), and/or restenosis (>3.5× step-up by duplex criteria) events (RAS). The secondary outcomes included all-cause mortality, failure to cross the lesion by endovascular methods, and a comparison between bypass vs endovascular intervention. Kaplan-Meier estimates were used to determine the event rates at 1 and 5 years, and Cox regression analysis was used to adjust for baseline differences among the GLASS stages.

Results: Of all patients undergoing first-time revascularization, imaging studies were available for 1180 procedures (91%) for GLASS grading. Of these procedures, 552 were open bypass (47%) and 628 were endovascular intervention (53%). Compared with GLASS stage 1 disease (n = 267, 23%), stage 2 (n = 367; 31%) and stage 3 (n = 546; 42%) disease were associated with a greater risk of RAS at 1 year (stage 1, 33% vs stage 2, 48% vs stage 3, 53%) and 5 years (stage 1, 45% [reference]; stage 2, 65%; hazard ratio [HR], 1.7; 95% confidence interval [CI], 1.3-2.2; P < .001; stage 3, 69%; HR, 2.3; 95% CI, 1.7-2.9; P < .001). These differences were mainly driven by reintervention and restenosis rather than by major amputation. The 5-year mortality was similar for stage 2 and 3 compared with stage 1 disease (stage 1, 40% [reference]; stage 2, 45%; HR, 1.1; 95% CI, 0.8-1.4; P = .69; stage 3, 49%; HR, 1.2; 95% CI, 1.0-1.6; P = .11). For all attempted endovascular interventions, failure to cross a target lesion increased with advancing GLASS stage (stage 1, 4.5% vs stage 2, 6.3% vs stage 3, 13.3%; P < .01). Compared with open bypass (n = 552; 46.8%), endovascular intervention (n = 628; 53.3%) was associated with a higher rate of 5-year RAS for GLASS stage 1 (49% vs 34%; HR, 1.9; 95% CI, [1.1-3.5; P = .03), stage 2 (69% vs 52%; HR, 1.7; 95% CI, 1.2-2.5; P < .01), and stage 3 (83% vs 61%; HR, 1.5; 95% CI, 1.2-2.0; P < .01) disease.

Conclusions: For patients undergoing first-time lower extremity revascularization, the GLASS can be used to predict for reintervention and restenosis. Bypass resulted in better long-term outcomes compared with endovascular intervention for all GLASS stages.
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http://dx.doi.org/10.1016/j.jvs.2020.08.151DOI Listing
October 2020

Ultrafast Singlet Fission and Intersystem Crossing in Halogenated Tetraazaperopyrenes.

J Phys Chem A 2020 Oct 22;124(39):7857-7868. Epub 2020 Sep 22.

Physikalisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 229, D-69120 Heidelberg, Germany.

Charge carrier multiplication via singlet fission into two triplet states has the potential to increase efficiencies of photovoltaics by one-third due to the reduction of thermalization losses. In the present work, we investigate tetraazaperopyrenes, a class of -heteropolycyles, as suitable singlet fission candidates. Using a combined experimental and theoretical approach, fundamentally different mechanisms for triplet formation in solution and thin film are identified. In solution, an ultrafast intersystem crossing process is observed, which is accelerated for heavier halide substituents not only due to enhanced spin-orbit coupling but also due to the energy tuning between the S and T states. In thin films, a correlated triplet pair is formed coherently upon photoexcitation. Subsequently, an excimer formation is observed, which competes with the electronic decorrelation of the triplet pair. The comparison with peropyrene shows that aza-substitutions within the aromatic core can be a powerful strategy for tuning the energy levels of the states important to singlet fission.
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http://dx.doi.org/10.1021/acs.jpca.0c04852DOI Listing
October 2020

Site-Selective Oxidation of Monolayered Liquid-Exfoliated WS by Shielding the Basal Plane through Adsorption of a Facial Amphiphile.

Angew Chem Int Ed Engl 2020 Aug 25;59(33):13785-13792. Epub 2020 Jun 25.

Institute for Physical Chemistry, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 253, 69120, Heidelberg, Germany.

In recent years, various functionalization strategies for transition-metal dichalcogenides have been explored to tailor the properties of materials and to provide anchor points for the fabrication of hybrid structures. Herein, new insights into the role of the surfactant in functionalization reactions are described. Using the spontaneous reaction of WS with chloroauric acid as a model reaction, the regioselective formation of gold nanoparticles on WS is shown to be heavily dependent on the surfactant employed. A simple model is developed to explain the role of the chosen surfactant in this heterogeneous functionalization reaction. The surfactant coverage is identified as the crucial element that governs the dominant reaction pathway and therefore can severely alter the reaction outcome. This study shows the general importance of the surfactant choice and how detrimental or beneficial a certain surfactant can be to the desired functionalization.
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http://dx.doi.org/10.1002/anie.202005730DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7496821PMC
August 2020

Collateral status contributes to differences between observed and predicted 24-h infarct volumes in DEFUSE 3.

J Cereb Blood Flow Metab 2020 10 19;40(10):1966-1974. Epub 2020 May 19.

Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA, USA.

We previously demonstrated that in the DEFUSE 3 trial, the union of the baseline core and the 24-h Tmax > 6 s perfusion lesion predicts the infarct volume at 24 h. Presently, we assessed if collateral robustness measured by the hypoperfusion intensity ratio (HIR) and cerebral blood volume (CBV) index accounts for the variance in these predictions. DEFUSE 3 patients underwent MRI/CT perfusion imaging at baseline and 24 h post-randomization. We compared baseline and follow-up HIR and CBV index across subgroups stratified by differences between predicted and observed 24-h infarct volumes. Of 123 eligible patients, 34 with 24-h infarcts larger than predicted had less favorable collaterals at baseline (HIR 0.43 vs. 0.32,  = 0.006; CBV Index 0.78 vs. 0.85,  = 0.001) and 24 h (HIR 0.56 vs. 0.07,  = 0.004; CBV Index 0.47 vs. 0.73,  = 0.006) compared to 71 patients with more accurate infarct volume prediction. Eighteen patients with 24-h infarcts smaller than predicted had similar baseline collateral scores but more favorable 24-h CBV indices (0.81 vs. 0.73,  = 0.040). Overall, patients with 24-h infarcts larger than predicted had evidence of less favorable baseline collaterals that fail within 24 h, while patients with 24-h infarcts smaller than predicted typically had favorable collaterals that persisted for 24 h.
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http://dx.doi.org/10.1177/0271678X20918816DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7786839PMC
October 2020

Contemporary outcomes after carotid endarterectomy in high-risk anatomic and physiologic patients.

J Vasc Surg 2020 01 20;71(1):104-110. Epub 2019 Aug 20.

Department of Vascular and Endovascular Surgery, Beth Israel Deaconess Medical Center, Boston, Mass. Electronic address:

Objective: Current guidelines state that the acceptable 30-day postoperative stroke/death rate after carotid endarterectomy (CEA) is <3% for asymptomatic patients and <6% for symptomatic patients. The Centers for Medicare and Medicaid Services has identified certain high-risk characteristics used to define patients at highest risk for CEA for whom carotid artery stenting would be reimbursed. We evaluated the impact of the Centers for Medicare and Medicaid Services physiologic and anatomic high-risk criteria on major adverse event rates after CEA in asymptomatic and symptomatic patients.

Methods: We retrospectively reviewed all patients undergoing CEA from 2011 to 2017 in the American College of Surgeons National Surgical Quality Improvement Program vascular targeted database. Patients with high-risk anatomic or physiologic characteristics were identified by a predefined variable and were compared with normal-risk patients. The primary outcome was 30-day stroke/death, stratified by symptom status.

Results: We identified 25,788 patients undergoing CEA, of whom 60% were treated for asymptomatic carotid disease. Among all patients, high-risk physiology or anatomy was associated with higher rates of 30-day stroke/death compared with normal-risk patients (physiologic risk, 4.6% vs 2.3% [P < .001]; anatomic risk, 3.6% vs 2.3% [P < .001]). Patients who met criteria for high-risk physiology or anatomy also had higher rates of cardiac events (physiologic risk, 3.1% vs 1.6% [P < .001]; anatomic risk, 2.3% vs 1.6% [P < .01]), but only patients with high-risk anatomy had higher rates of cranial nerve injury (physiologic risk, 2.4% vs 2.5% [P = .81]; anatomic risk, 4.3% vs 2.5% [P < .001]). Asymptomatic patients with high-risk physiology or anatomy had higher rates of 30-day stroke/death, especially in the physiologic high-risk group (physiologic risk, 4.7% vs 1.5% [P < .001]; anatomic risk, 2.6% vs 1.5% [P < .01]), compared with normal-risk patients. However, among symptomatic patients, differences in stroke/death were seen only with high-risk anatomic patients and not with high-risk physiologic patients (physiologic risk, 4.6% vs 3.4% [P = .12]; anatomic risk, 4.8% vs 3.4% [P = .01]).

Conclusions: As currently selected, contemporary real-world outcomes after CEA in asymptomatic carotid disease patients meeting high-risk physiologic criteria show an unacceptably high 30-day stroke/death rate, well above the 3% threshold. These results suggest the need for better selection of patients and preoperative optimization before elective CEA.
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http://dx.doi.org/10.1016/j.jvs.2019.05.041DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6926142PMC
January 2020

Ischemic Core and Hypoperfusion Volumes Correlate With Infarct Size 24 Hours After Randomization in DEFUSE 3.

Stroke 2019 03;50(3):626-631

From the Department of Neurology and Neurological Sciences (V.R., S.C., A.Y., M.M., M.G.L., G.W.A.), Stanford University School of Medicine, CA.

Background and Purpose- Accurate prediction of the subsequent infarct volume early after stroke onset helps determine appropriate interventions and prognosis. In the DEFUSE 3 trial (Endovascular Therapy Following Imaging Evaluation for Ischemic Stroke), we evaluated the accuracy of baseline ischemic core and hypoperfusion volumes for predicting infarct volume 24 hours after randomization to endovascular thrombectomy versus medical management. We also assessed if the union of baseline ischemic core and the volume of persistent hypoperfusion at 24 hours after randomization predicts infarct volume. Methods- Patients in DEFUSE 3 with computed tomography perfusion imaging or magnetic resonance diffusion weighted imaging/perfusion imaging acquired at baseline and at 24 hours after randomization were included. Ischemic core and Tmax >6s hypoperfusion volumes at baseline and follow-up were calculated using RAPID software and compared with the infarct volumes obtained 24 hours after randomization. Patients were stratified by reperfusion status for analyses. Results- Of 125 eligible patients, 59 patients with >90% reperfusion had a strong correlation between baseline ischemic core volume and infarct volume 24 hours postrandomization ( r=0.83; P<0.0001), and 14 patients with <10% reperfusion had a strong correlation between baseline Tmax >6s volume and infarct volume 24 hours postrandomization ( r=0.77; P<0.001). In the 52 patients with 10% to 90% reperfusion, as well as in all 125 patients, the union of the baseline ischemic core and the follow-up Tmax >6s perfusion volume was highly correlated with infarct volume 24 hours postrandomization (for N=125; r=0.83; P<0.0001), with a median absolute difference of 21.3 mL between observed and predicted infarct volumes. Conclusions- The union of the irreversibly injured ischemic core and persistently hypoperfused tissue volumes, as identified by computed tomography perfusion or magnetic resonance diffusion weighted imaging/perfusion, predicted infarct volume at 24 hours after randomization in DEFUSE 3 patients. Clinical Trial Registration- URL: https://www.clinicaltrials.gov . Unique identifier: NCT02586415.
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http://dx.doi.org/10.1161/STROKEAHA.118.023177DOI Listing
March 2019

Vascular Risk and β-Amyloid Are Synergistically Associated with Cortical Tau.

Ann Neurol 2019 02 7;85(2):272-279. Epub 2019 Jan 7.

Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA.

Objective: Neuropathological studies have demonstrated that cerebrovascular disease and Alzheimer disease (AD) pathology frequently co-occur in older adults. The extent to which cerebrovascular disease influences the progression of AD pathology remains unclear. Leveraging newly available positron emission tomography (PET) imaging, we examined whether a well-validated measure of systemic vascular risk and β-amyloid (Aβ) burden have an interactive association with regional tau burden.

Methods: Vascular risk was quantified at baseline in 152 clinically normal older adults (mean age = 73.5 ± 6.1 years) with the office-based Framingham Heart Study cardiovascular disease risk algorithm (FHS-CVD). We acquired Aβ ( C-Pittsburgh compound B) and tau ( F-flortaucipir) PET imaging on the same participants. Aβ PET was performed at baseline; tau PET was acquired on average 2.98 ± 1.1 years later. Tau was measured in the entorhinal cortex (EC), an early site of tau deposition, and in the inferior temporal cortex (ITC), an early site of neocortical tau accumulation associated with AD. Linear regression models examined FHS-CVD and Aβ as interactive predictors of tau deposition, adjusting for age, sex, APOE ε4 status, and the time interval between baseline and the tau PET scan.

Results: We observed a significant interaction between FHS-CVD and Aβ burden on subsequently measured ITC tau (p < 0.001), whereby combined higher FHS-CVD and elevated Aβ burden was associated with increased tau. The interaction was not significant for EC tau (p = 0.16).

Interpretation: Elevated vascular risk may influence tau burden when coupled with high Aβ burden. These results suggest a potential link between vascular risk and tau pathology in preclinical AD. Ann Neurol 2019; 1-8 ANN NEUROL 2019;85:272-279.
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http://dx.doi.org/10.1002/ana.25399DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6351182PMC
February 2019

Human Defensin-5 Blocks Ethanol and Colitis-Induced Dysbiosis, Tight Junction Disruption and Inflammation in Mouse Intestine.

Sci Rep 2018 11 2;8(1):16241. Epub 2018 Nov 2.

Department of Physiology, University of Tennessee Health Science Center, Memphis, TN, 38103, USA.

Alcohol consumption has been shown to cause dysbiosis, but the mechanism involved in it is unknown. Recurrent colitis is known to induce expression of α-defensins in the colon, but the effect of alcohol consumption on it is not known. We investigated the effect of ethanol on α-defensin expression in the small intestine and colitis-induced expression in colon in mice. Furthermore, we evaluated the effect of human defensin-5 (HD5) on ethanol and colitis-induced gut barrier dysfunction and mucosal damage. Recurrent colitis was induced by feeding dextran sulfate sodium (DSS), 3 cycles of 5-days each with 15 days intervals, followed by 30-days remission. Ethanol was fed during the intervals and recovery in a liquid diet with or without HD5. Expression of α-defensins, tight junction (TJ) integrity and cytokine/chemokine expression were analyzed. Chronic ethanol feeding reduced α-defensin expression in the small intestine and colitis-induced defensin expression in the colon. HD5 attenuated the growth of enterotoxigenic Bacteriodes fragilis and E. coli, but had no effect on non-toxigenic Bacteriodes fragilis or probiotics, the Lactobacilli. Ethanol and colitis elevated Enterobacteriaceae, Firmicutes and Firmicutes to Bacteriodetes ratio in colonic mucosa. HD5 feeding attenuated ethanol and colitis-induced dysbiosis, disruption of intestinal epithelial TJ, mucosal inflammation, expression of pro-inflammatory cytokines and chemokines in the small intestine and colon, and endotoxemia. These results demonstrate that ethanol suppresses intestinal α-defensin expression, leading to dysbiosis, barrier dysfunction, inflammation and endotoxemia. HD5 feeding attenuates intestinal injury caused by ethanol and colitis, indicating that defensin expression is a potential target for treatment of alcoholic tissue injury and colitis.
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http://dx.doi.org/10.1038/s41598-018-34263-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6214960PMC
November 2018

Interactive Associations of Vascular Risk and β-Amyloid Burden With Cognitive Decline in Clinically Normal Elderly Individuals: Findings From the Harvard Aging Brain Study.

JAMA Neurol 2018 09;75(9):1124-1131

Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston.

Importance: Identifying asymptomatic individuals at high risk of impending cognitive decline because of Alzheimer disease is crucial for successful prevention of dementia. Vascular risk and β-amyloid (Aβ) pathology commonly co-occur in older adults and are significant causes of cognitive impairment.

Objective: To determine whether vascular risk and Aβ burden act additively or synergistically to promote cognitive decline in clinically normal older adults; and, secondarily, to evaluate the unique influence of vascular risk on prospective cognitive decline beyond that of commonly used imaging biomarkers, including Aβ burden, hippocampal volume, fludeoxyglucose F18-labeled (FDG) positron emission tomography (PET), and white matter hyperintensities, a marker of cerebrovascular disease.

Design, Setting, And Participants: In this longitudinal observational study, we examined clinically normal older adults from the Harvard Aging Brain Study. Participants were required to have baseline imaging data (FDG-PET, Aβ-PET, and magnetic resonance imaging), baseline medical data to quantify vascular risk, and at least 1 follow-up neuropsychological visit. Data collection began in 2010 and is ongoing. Data analysis was performed on data collected between 2010 and 2017.

Main Outcomes And Measures: Vascular risk was quantified using the Framingham Heart Study general cardiovascular disease (FHS-CVD) risk score. We measured Aβ burden with Pittsburgh Compound-B PET. Cognition was measured annually with the Preclinical Alzheimer Cognitive Composite. Models were corrected for baseline age, sex, years of education, and apolipoprotein E ε4 status.

Results: Of the 223 participants, 130 (58.3%) were women. The mean (SD) age was 73.7 (6.0) years, and the mean (SD) follow-up time was 3.7 (1.2) years. Faster cognitive decline was associated with both a higher FHS-CVD risk score (β = -0.064; 95% CI, -0.094 to -0.033; P < .001) and higher Aβ burden (β = -0.058; 95% CI, -0.079 to -0.037; P < .001). The interaction of the FHS-CVD risk score and Aβ burden with time was significant (β = -0.040, 95% CI, -0.062 to -0.018; P < .001), suggesting a synergistic effect. The FHS-CVD risk score remained robustly associated with prospective cognitive decline (β = -0.055; 95% CI, -0.086 to -0.024; P < .001), even after adjustment for Aβ burden, hippocampal volume, FDG-PET uptake, and white matter hyperintensities.

Conclusions And Relevance: In this study, vascular risk was associated with prospective cognitive decline in clinically normal older adults, both alone and synergistically with Aβ burden. Vascular risk may complement imaging biomarkers in assessing risk of prospective cognitive decline in preclinical Alzheimer disease.
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http://dx.doi.org/10.1001/jamaneurol.2018.1123DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6143121PMC
September 2018