Browsing by Author "Sharma, Richa"

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    Acute Ischemic Stroke, Depressed Left Ventricular Ejection Fraction, and Sinus Rhythm: Prevalence and Practice Patterns
    (American Heart Association, 2022) Baker, Anna D.; Schwamm, Lee H.; Sanborn, Danita Y.; Furie, Karen; Stretz, Christoph; Grory, Brian Mac; Yaghi, Shadi; Kleindorfer, Dawn; Sucharew, Heidi; Mackey, Jason; Walsh, Kyle; Flaherty, Matt; Kissela, Brett; Alwell, Kathleen; Khoury, Jane; Khatri, Pooja; Adeoye, Opeolu; Ferioli, Simona; Woo, Daniel; Martini, Sharyl; De Los Rios La Rosa, Felipe; Demel, Stacie L.; Madsen, Tracy; Star, Michael; Coleman, Elisheva; Slavin, Sabreena; Jasne, Adam; Mistry, Eva A.; Haverbusch, Mary; Merkler, Alexander E.; Kamel, Hooman; Schindler, Joseph; Sansing, Lauren H.; Faridi, Kamil F.; Sugeng, Lissa; Sheth, Kevin N.; Sharma, Richa; Neurology, School of Medicine
    Background: There are limited data about the epidemiology and secondary stroke prevention strategies used for patients with depressed left ventricular ejection fraction (LVEF) and sinus rhythm following an acute ischemic stroke (AIS). We sought to describe the prevalence of LVEF ≤40% and sinus rhythm among patients with AIS and antithrombotic treatment practice in a multi-center cohort from 2002 to 2018. Methods: This was a multi-center, retrospective cohort study comprised of patients with AIS hospitalized in the Greater Cincinnati Northern Kentucky Stroke Study and 4 academic, hospital-based cohorts in the United States. A 1-stage meta-analysis of proportions was undertaken to calculate a pooled prevalence. Univariate analyses and an adjusted multivariable logistic regression model were performed to identify demographic, clinical, and echocardiographic characteristics associated with being prescribed an anticoagulant upon AIS hospitalization discharge. Results: Among 14 338 patients with AIS with documented LVEF during the stroke hospitalization, the weighted pooled prevalence of LVEF ≤40% and sinus rhythm was 5.0% (95% CI, 4.1-6.0%; I2, 84.4%). Of 524 patients with no cardiac thrombus and no prior indication for anticoagulant who survived postdischarge, 200 (38%) were discharged on anticoagulant, 289 (55%) were discharged on antiplatelet therapy only, and 35 (7%) on neither. There was heterogeneity by site in the proportion discharged with an anticoagulant (22% to 45%, P<0.0001). Cohort site and National Institutes of Health Stroke Severity scale >8 (odds ratio, 2.0 [95% CI, 1.1-3.8]) were significant, independent predictors of being discharged with an anticoagulant in an adjusted analysis. Conclusions: Nearly 5% of patients with AIS have a depressed LVEF and are in sinus rhythm. There is significant variation in the clinical practice of antithrombotic therapy prescription by site and stroke severity. Given this clinical equipoise, further study is needed to define optimal antithrombotic treatment regimens for secondary stroke prevention in this patient population.
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    Evaluation and Management of Chronic Pancytopenia
    (AAP, 2016-03) Sharma, Richa; Nalepa, Grzegorz; Department of Pediatrics, IU School of Medicine
    Diagnostic evaluation and management of children with chronic pancytopenia is highly complex. (1)(2)(3) Clinicians should be aware of the subtle signs and symptoms of acquired and congenital childhood pancytopenias to maintain a high index of suspicion, streamline the referral process, and function within their patients’ multidisciplinary medical homes.
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    Hyperactive Ras/MAPK signaling is critical for tibial nonunion fracture in neurofibromin-deficient mice
    (Oxford University Press, 2013-12-01) Sharma, Richa; Wu, Xiaohua; Rhodes, Steven D.; Chen, Shi; He, Yongzheng; Yuan, Jin; Li, Jiliang; Yang, Xianlin; Li, Xiaohong; Jiang, Li; Kim, Edward T.; Stevenson, David A.; Viskochil, David; Xu, Mingjiang; Yang, Feng-Chun; Department of Pediatrics, IU School of Medicine
    Neurofibromatosis type 1 (NF1) is a common genetic disorder affecting 1 in 3500 individuals. Patients with NF1 are predisposed to debilitating skeletal manifestations, including osteopenia/osteoporosis and long bone pseudarthrosis (nonunion fracture). Hyperactivation of the Ras/mitogen-activated protein kinase (MAPK) pathway in NF1 is known to underlie aberrant proliferation and differentiation in cell lineages, including osteoclast progenitors and mesenchymal stem cells (MSCs) also known as osteoblast progenitors (pro-OBLs). Our current study demonstrates the hyper Ras/MAPK as a critical pathway underlying the pathogenesis of NF1-associated fracture repair deficits. Nf1-deficient pro-OBLs exhibit Ras/MAPK hyperactivation. Introduction of the NF1 GTPase activating-related domain (NF1 GAP-related domain) in vitro is sufficient to rescue hyper Ras activity and enhance osteoblast (OBL) differentiation in Nf1−/− pro-OBLs and NF1 human (h) MSCs cultured from NF1 patients with skeletal abnormalities, including pseudarthrosis or scoliosis. Pharmacologic inhibition of mitogen-activated protein kinase kinase (MEK) signaling with PD98059 partially rescues aberrant Erk activation while enhancing OBL differentiation and expression of OBL markers, osterix and osteocalcin, in Nf1-deficient murine pro-OBLs. Similarly, MEK inhibition enhances OBL differentiation of hMSCs. In addition, PD98059 rescues aberrant osteoclast maturation in Nf1 haploinsufficient bone marrow mononuclear cells (BMMNCs). Importantly, MEK inhibitor significantly improves fracture healing in an NF1 murine model, Col2.3Cre
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    Hyperactive RAS/PI3-K/MAPK Signaling Cascade in Migration and Adhesion of Nf1 Haploinsufficient Mesenchymal Stem/Progenitor Cells
    (MDPI, 2015-06) Zhou, Yuan; He, Yongzheng; Sharma, Richa; Xing, Wen; Estwick, Selina A.; Wu, Xiaohua; Rhodes, Steven D.; Xu, Mingjiang; Yang, Feng-Chun; Department of Pediatrics, Indiana University School of Medicine
    Neurofibromatosis type 1 (NF1) is an autosomal dominant disease caused by mutations in the NF1 tumor suppressor gene, which affect approximately 1 out of 3000 individuals. Patients with NF1 suffer from a range of malignant and nonmalignant manifestations such as plexiform neurofibromas and skeletal abnormalities. We previously demonstrated that Nf1 haploinsufficiency in mesenchymal stem/progenitor cells (MSPCs) results in impaired osteoblastic differentiation, which may be associated with the skeletal manifestations in NF1 patients. Here we sought to further ascertain the role of Nf1 in modulating the migration and adhesion of MSPCs of the Nf1 haploinsufficient (Nf1+/−) mice. Nf1+/− MSPCs demonstrated increased nuclear-cytoplasmic ratio, increased migration, and increased actin polymerization as compared to wild-type (WT) MSPCs. Additionally, Nf1+/− MSPCs were noted to have significantly enhanced cell adhesion to fibronectin with selective affinity for CH271 with an overexpression of its complimentary receptor, CD49e. Nf1+/− MSPCs also showed hyperactivation of phosphoinositide 3-kinase (PI3-K) and mitogen activated protein kinase (MAPK) signaling pathways when compared to WT MSPCs, which were both significantly reduced in the presence of their pharmacologic inhibitors, LY294002 and PD0325901, respectively. Collectively, our study suggests that both PI3-K and MAPK signaling pathways play a significant role in enhanced migration and adhesion of Nf1 haploinsufficient MSPCs.
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    Mitotic Errors Promote Genomic Instability and Leukemia in a Novel Mouse Model of Fanconi Anemia
    (Frontiers Media, 2021-11-05) Edwards, Donna M.; Mitchell, Dana K.; Abdul-Sater, Zahi; Chan, Ka-Kui; Sun, Zejin; Sheth, Aditya; He, Ying; Jiang, Li; Yuan, Jin; Sharma, Richa; Czader, Magdalena; Chin, Pei-Ju; Liu, Yie; de Cárcer, Guillermo; Nalepa, Grzegorz; Broxmeyer, Hal E.; Clapp, D. Wade; Potchanant, Elizabeth A. Sierra; Pediatrics, School of Medicine
    Fanconi anemia (FA) is a disease of genomic instability and cancer. In addition to DNA damage repair, FA pathway proteins are now known to be critical for maintaining faithful chromosome segregation during mitosis. While impaired DNA damage repair has been studied extensively in FA-associated carcinogenesis in vivo, the oncogenic contribution of mitotic abnormalities secondary to FA pathway deficiency remains incompletely understood. To examine the role of mitotic dysregulation in FA pathway deficient malignancies, we genetically exacerbated the baseline mitotic defect in Fancc-/- mice by introducing heterozygosity of the key spindle assembly checkpoint regulator Mad2. Fancc-/-;Mad2+/- mice were viable, but died from acute myeloid leukemia (AML), thus recapitulating the high risk of myeloid malignancies in FA patients better than Fancc-/-mice. We utilized hematopoietic stem cell transplantation to propagate Fancc-/-; Mad2+/- AML in irradiated healthy mice to model FANCC-deficient AMLs arising in the non-FA population. Compared to cells from Fancc-/- mice, those from Fancc-/-;Mad2+/- mice demonstrated an increase in mitotic errors but equivalent DNA cross-linker hypersensitivity, indicating that the cancer phenotype of Fancc-/-;Mad2+/- mice results from error-prone cell division and not exacerbation of the DNA damage repair defect. We found that FANCC enhances targeting of endogenous MAD2 to prometaphase kinetochores, suggesting a mechanism for how FANCC-dependent regulation of the spindle assembly checkpoint prevents chromosome mis-segregation. Whole-exome sequencing revealed similarities between human FA-associated myelodysplastic syndrome (MDS)/AML and the AML that developed in Fancc-/-; Mad2+/- mice. Together, these data illuminate the role of mitotic dysregulation in FA-pathway deficient malignancies in vivo, show how FANCC adjusts the spindle assembly checkpoint rheostat by regulating MAD2 kinetochore targeting in cell cycle-dependent manner, and establish two new mouse models for preclinical studies of AML.
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    SIK2 kinase synthetic lethality is driven by spindle assembly defects in FANCA‐deficient cells
    (Wiley, 2022-02) Chan, Ka‐Kui; Abdul‐Sater, Zahi; Sheth, Aditya; Mitchell, Dana K.; Sharma, Richa; Edwards, Donna M.; He, Ying; Nalepa, Grzegorz; Rhodes, Steven D.; Clapp, D. Wade; Potchanant, Elizabeth A. Sierra; Pediatrics, School of Medicine
    The Fanconi anemia (FA) pathway safeguards genomic stability through cell cycle regulation and DNA damage repair. The canonical tumor suppressive role of FA proteins in the repair of DNA damage during interphase is well established, but their function in mitosis is incompletely understood. Here, we performed a kinome‐wide synthetic lethality screen in FANCA −/− fibroblasts, which revealed multiple mitotic kinases as necessary for survival of FANCA‐deficient cells. Among these kinases, we identified the depletion of the centrosome kinase SIK2 as synthetic lethal upon loss of FANCA. We found that FANCA colocalizes with SIK2 at multiple mitotic structures and regulates the activity of SIK2 at centrosomes. Furthermore, we found that loss of FANCA exacerbates cell cycle defects induced by pharmacological inhibition of SIK2, including impaired G2‐M transition, delayed mitotic progression, and cytokinesis failure. In addition, we showed that inhibition of SIK2 abrogates nocodazole‐induced prometaphase arrest, suggesting a novel role for SIK2 in the spindle assembly checkpoint. Together, these findings demonstrate that FANCA‐deficient cells are dependent upon SIK2 for survival, supporting a preclinical rationale for targeting of SIK2 in FA‐disrupted cancers.
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    Transanal endoscopic microsurgery: The first attempt in treatment of rectal amyloidoma
    (Baishideng Publishing Group, 2015-01-28) Sharma, Richa; George, Virgilio; Department of Medicine, IU School of Medicine
    Localized amyloidosis is characterized by amyloid protein deposition restricted to one organ or tissue without systemic involvement. Gastrointestinal manifestations of localized amyloidoma are unusual, which makes amyloidoma restricted to the rectum a very rare diagnosis requiring a high index of suspicion. We present a rare account for rectal amyloidoma with an unusual presentation of obstructive symptoms and its treatment using a sophisticated surgical modality, transanal endoscopic microsurgery (TEM), which resulted in complete excision of the lesion without hospitalization and complications. The successful treatment for this rectal amyloidoma using TEM emphasizes the need to broaden its application in the treatment of various rectal lesions while preserving organ function and decreasing recurrence.