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"Kim, Esther E."
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Oxidative Stress and Neuronal Death/Survival Signaling in Cerebral Ischemia
2005
It has been demonstrated by numerous studies that apoptotic cell death pathways are implicated in ischemic cerebral injury in ischemia models in vivo. Experimental ischemia and reperfusion models, such as transient focal/global ischemia in rodents, have been thoroughly studied and the numerous reports suggest the involvement of cell survival/death signaling pathways in the pathogenesis of apoptotic cell death in ischemic lesions. In these models, reoxygenation during reperfusion provides oxygen as a substrate for numerous enzymatic oxidation reactions and for mitochondrial oxidative phosphorylation to produce adenosine triphosphate. Oxygen radicals, the products of these biochemical and physiological reactions, are known to damage cellular lipids, proteins, and nucleic acids and to initiate cell signaling pathways after cerebral ischemia. Genetic manipulation of intrinsic antioxidants and factors in the signaling pathways has provided substantial understanding of the mechanisms involved in cell death/survival signaling pathways and the role of oxygen radicals in ischemic cerebral injury. Future studies of these pathways could provide novel therapeutic strategies in clinical stroke.
Journal Article
Bariatric Surgery versus Intensive Medical Therapy for Diabetes — 3-Year Outcomes
by
Kirwan, John P
,
Bhatt, Deepak L
,
Kashyap, Sangeeta R
in
Adult
,
Biological and medical sciences
,
Biomarkers - blood
2014
At 3 years of follow-up, among obese patients with uncontrolled type 2 diabetes who were randomly assigned to receive intensive medical therapy with or without bariatric surgery, significantly more patients in the surgery groups achieved glycemic control.
Bariatric surgery has recently emerged as a potentially useful treatment for type 2 diabetes mellitus.
1
Observational studies
2
–
5
and randomized, controlled trials
6
–
10
have shown that procedures including Roux-en-Y gastric bypass, sleeve gastrectomy, gastric banding, and biliopancreatic diversion significantly improve glycemic control and favorably affect cardiovascular risk factors.
In the Surgical Treatment and Medications Potentially Eradicate Diabetes Efficiently (STAMPEDE) trial, we found that 1 year after randomization, gastric bypass and sleeve gastrectomy were superior to intensive medical therapy alone in achieving glycemic control and reducing cardiovascular risk factors while decreasing dependency on pharmacotherapy for diabetes management.
7
Although bariatric surgery yields . . .
Journal Article
Mediation analysis of triple networks revealed functional feature of mindfulness from real-time fMRI neurofeedback
2019
The triple networks, namely the default-mode network (DMN), the central executive network (CEN), and the salience network (SN), play crucial roles in disorders of the brain, as well as in basic neuroscientific processes such as mindfulness. However, currently, there is no consensus on the underlying functional features of the triple networks associated with mindfulness. In this study, we tested the hypothesis that (a) the partial regression coefficient (i.e., slope): from the SN to the DMN, mediated by the CEN, would be one of the potential mindfulness features in the real-time functional magnetic resonance imaging (rtfMRI) neurofeedback (NF) setting, and (b) this slope level may be enhanced by rtfMRI-NF training. Sixty healthy mindfulness-naïve males participated in an MRI session consisting of two non-rtfMRI-runs, followed by two rtfMRI-NF runs and one transfer run. Once the regions-of-interest of each of the triple networks were defined using the non-rtfMRI-runs, the slope level was calculated by mediation analysis and used as neurofeedback information, in the form of a thermometer bar, to assist with participant mindfulness during the rtfMRI-NF runs. The participants were asked to increase the level of the thermometer bar while deploying a mindfulness strategy, which consisted of focusing attention on the physical sensations of breathing. rtfMRI-NF training was conducted as part of a randomized controlled trial design, in which participants were randomly assigned to either an experimental group or a control group. The participants in the experimental group received contingent neurofeedback information, which was obtained from their own brain signals, whereas the participants in the control group received non-contingent neurofeedback information that originated from matched participants in the experimental group. Our results indicated that the slope level from the SN to the DMN, mediated by the CEN, was associated with mindfulness score (rtfMRI-NF runs: r = 0.53, p = 0.007; p-value was corrected from 10,000 random permutations) and with task-performance feedback score (rtfMRI-NF run: r = 0.61, p = 0.001) in the experimental group only. In addition, during the rtfMRI-NF runs the level of the partial regression coefficient feature was substantially increased in the experimental group compared to the control group (p < 0.05 from the paired t-test; the p-value was corrected from 10,000 random permutations). To the best of our knowledge, this is the first study to demonstrate a partial regression coefficient feature of mindfulness in the rtfMRI-NF setting obtained by triple network mediation analysis, as well as the possibility of enhancement of the partial regression coefficient feature by rtfMRI-NF training.
•Mediation analysis using triple networks was employed to estimate functional feature of mindfulness (MF).•Real-time fMRI (rtfMRI) neurofeedback (NF) training based on this functional feature of MF was presented.•The partial regression coefficient from the SN to the DMN, mediated by the CEN appeared to be a potential feature of MF.•The validity of this functional feature of MF was evaluated by comparing alternative functional connectivity levels in the triple networks.•The possibility of enhancement of this functional feature of MF was demonstrated via rtfMRI-NFbased training.
Journal Article
Pirfenidone: A Review of Its Use in Idiopathic Pulmonary Fibrosis
2015
Pirfenidone (Esbriet
®
) is an orally administered, synthetic, pyridone compound that is approved for the treatment of adults with mild to moderate idiopathic pulmonary fibrosis (IPF) in the EU, and for the treatment of IPF in the USA. This article summarizes pharmacological, efficacy and tolerability data relevant to the use of pirfenidone in these indications. In the randomized, double-blind, placebo-controlled, multinational CAPACITY trials in patients with mild to moderate IPF, a significant reduction in the rate of decline in forced vital capacity (FVC) was seen with pirfenidone versus placebo in study 004 but not in study 006. Pirfenidone also reduced the rate of decline in FVC to a significantly greater extent than placebo in the randomized, double-blind, multinational ASCEND trial in this patient population. In addition, pirfenidone showed a significant treatment effect on the 6-min walking test distance and progression-free survival in the ASCEND trial and in a pooled analysis of the CAPACITY trials. Pirfenidone had a manageable tolerability profile in all three studies. Gastrointestinal and skin-related events (e.g. nausea, rash, photosensitivity reaction), which were the most commonly occurring treatment-emergent adverse events, were generally mild to moderate in severity. In addition, a prespecified mortality analysis across all three studies demonstrated a significant reduction in IPF-related and all-cause mortality with pirfenidone. In conclusion, oral pirfenidone is a valuable agent for use in patients with IPF.
Journal Article
A20 critically controls microglia activation and inhibits inflammasome-dependent neuroinflammation
2018
Microglia, the mononuclear phagocytes of the central nervous system (CNS), are important for the maintenance of CNS homeostasis, but also critically contribute to CNS pathology. Here we demonstrate that the nuclear factor kappa B (NF-κB) regulatory protein A20 is crucial in regulating microglia activation during CNS homeostasis and pathology. In mice, deletion of A20 in microglia increases microglial cell number and affects microglial regulation of neuronal synaptic function. Administration of a sublethal dose of lipopolysaccharide induces massive microglia activation, neuroinflammation, and lethality in mice with microglia-confined A20 deficiency. Microglia A20 deficiency also exacerbates multiple sclerosis (MS)-like disease, due to hyperactivation of the Nlrp3 inflammasome leading to enhanced interleukin-1β secretion and CNS inflammation. Finally, we confirm a Nlrp3 inflammasome signature and IL-1β expression in brain and cerebrospinal fluid from MS patients. Collectively, these data reveal a critical role for A20 in the control of microglia activation and neuroinflammation.
As resident macrophages of the brain, microglia are important for neuroinflammatory responses. This work shows that nuclear factor kappa B regulatory protein A20 is important for microglia activation and regulation during inflammation of the central nervous system.
Journal Article
SMARCB1 Gene Therapy Using a Novel Tumor-Targeted Nanomedicine Enhances Anti-Cancer Efficacy in a Mouse Model of Atypical Teratoid Rhabdoid Tumors
by
Harford, Joe
,
Kim, Sang-Soo
,
Chang, Esther
in
Animals
,
Antineoplastic Agents - chemistry
,
Antineoplastic Agents - pharmacology
2024
Atypical teratoid rhabdoid tumor (ATRT) is a deadly, fast-growing form of pediatric brain cancer with poor prognosis. Most ATRTs are associated with inactivation of SMARCB1, a subunit of the chromatin remodeling complex, which is involved in developmental processes. The recent identification of SMARCB1 as a tumor suppressor gene suggests that restoration of SMARCB1 could be an effective therapeutic approach.
We tested SMARCB1 gene therapy in SMARCB1-deficient rhabdoid tumor cells using a novel tumor-targeted nanomedicine (termed scL-SMARCB1) to deliver wild-type SMARCB1. Our nanomedicine is a systemically administered immuno-lipid nanoparticle that can actively cross the blood-brain barrier via transferrin receptor-mediated transcytosis and selectively target tumor cells via transferrin receptor-mediated endocytosis. We studied the antitumor activity of the scL-SMARCB1 nanocomplex either as a single agent or in combination with traditional treatment modalities in preclinical models of SMARCB1-deficient ATRT.
Restoration of SMARCB1 expression by the scL-SMARCB1 nanocomplex blocked proliferation, and induced senescence and apoptosis in ATRT cells. Systemic administration of the scL-SMARCB1 nanocomplex demonstrated antitumor efficacy as monotherapy in mice bearing ATRT xenografts, where the expression of exogenous SMARCB1 modulates MYC-target genes. scL-SMARCB1 demonstrated even greater antitumor efficacy when combined with either cisplatin-based chemotherapy or radiation therapy, resulting in significantly improved survival of ATRT-bearing mice.
Collectively, our data suggest that restoring SMARCB1 function via the scL-SMARCB1 nanocomplex may lead to therapeutic benefits in ATRT patients when combined with traditional chemoradiation therapies.
Journal Article
A Pralidoxime Nanocomplex Formulation Targeting Transferrin Receptors for Reactivation of Brain Acetylcholinesterase After Exposure of Mice to an Anticholinesterase Organophosphate
2024
Organophosphates are among the deadliest of known chemicals based on their ability to inactivate acetylcholinesterase in neuromuscular junctions and synapses of the central and peripheral nervous systems. The consequent accumulation of acetylcholine can produce severe acute toxicities and death. Oxime antidotes act by reactivating acetylcholinesterase with the only such reactivator approved for use in the United States being 2-pyridine aldoxime methyl chloride (
., pralidoxime or 2-PAM). However, this compound does not cross the blood-brain barrier readily and so is limited in its ability to reactivate acetylcholinesterase in the brain.
We have developed a novel formulation of 2-PAM by encapsulating it within a nanocomplex designed to cross the blood-brain barrier via transferrin receptor-mediated transcytosis. This nanocomplex (termed scL-2PAM) has been subjected to head-to-head comparisons with unencapsulated 2-PAM in mice exposed to paraoxon, an organophosphate with anticholinesterase activity.
In mice exposed to a sublethal dose of paraoxon, scL-2PAM reduced the extent and duration of cholinergic symptoms more effectively than did unencapsulated 2-PAM. The scL-2PAM formulation was also more effective than unencapsulated 2-PAM in rescuing mice from death after exposure to otherwise-lethal levels of paraoxon. Improved survival rates in paraoxon-exposed mice were accompanied by a higher degree of reactivation of brain acetylcholinesterase.
Our data indicate that scL-2PAM is superior to the currently used form of 2-PAM in terms of both mitigating paraoxon toxicity in mice and reactivating acetylcholinesterase in their brains.
Journal Article
A unified in vitro evaluation for apatite-forming ability of bioactive glasses and their variants
The aim of this study was to propose and validate a new unified method for testing dissolution rates of bioactive glasses and their variants, and the formation of calcium phosphate layer formation on their surface, which is an indicator of bioactivity. At present, comparison in the literature is difficult as many groups use different testing protocols. An ISO standard covers the use of simulated body fluid on standard shape materials but it does not take into account that bioactive glasses can have very different specific surface areas, as for glass powders. Validation of the proposed modified test was through round robin testing and comparison to the ISO standard where appropriate. The proposed test uses fixed mass per solution volume ratio and agitated solution. The round robin study showed differences in hydroxyapatite nucleation on glasses of different composition and between glasses of the same composition but different particle size. The results were reproducible between research facilities. Researchers should use this method when testing new glasses, or their variants, to enable comparison between the literature in the future.
Journal Article
Cytoskeletal dynamics and mitochondrial rearrangements drive cell fate upon antibody-induced complement activation in DLBCL
by
Breij, Esther C. W.
,
Csikós, Tamás
,
de Lint, Klaas
in
631/250/251
,
631/250/262
,
631/67/1059/2326
2025
Complement-dependent cytotoxicity (CDC) is an important effector function of various therapeutic antibodies. Cancer resistance to CDC is primarily attributed to extracellular factors. Using diffuse large B-cell lymphoma (DLBCL) models, we elucidated intracellular evasion mechanisms. By CRISPR-Cas9 library screening, we identified mitochondrial damage and reactive oxygen species as the key intracellular drivers of CDC. CDC resistance was linked to augmented mitochondrial mass, elongated mitochondria and reduced mitophagy, and decreased expression of actin-related genes. Actin downregulation in CDC-resistant cells occurred specifically within the mitochondria, connecting mitochondrial rearrangements and cytoskeletal dynamics with resistance. Stimulating actin polymerization could partially overcome CDC resistance. Of clinical significance, we observed a positive association between the cytoskeleton and antibody responses in DLBCL patient samples. In conclusion, our study unveils novel intracellular resistance mechanisms to antibody-induced CDC, highlighting the critical roles of mitochondrial rearrangements and cytoskeletal dynamics in CDC. We propose that decreased mitochondrial actin prevents overload of the mitophagy pathway, thereby reducing CDC.
Journal Article
Murine fetal bone marrow does not support functional hematopoietic stem and progenitor cells until birth
2022
While adult bone marrow (BM) hematopoietic stem and progenitor cells (HSPCs) and their extrinsic regulation is well studied, little is known about the composition, function, and extrinsic regulation of the first HSPCs to enter the BM during development. Here, we functionally interrogate murine BM HSPCs from E15.5 through P0. Our work reveals that fetal BM HSPCs are present by E15.5, but distinct from the HSPC pool seen in fetal liver, both phenotypically and functionally, until near birth. We also generate a transcriptional atlas of perinatal BM HSPCs and the BM niche in mice across ontogeny, revealing that fetal BM lacks HSPCs with robust intrinsic stem cell programs, as well as niche cells supportive of HSPCs. In contrast, stem cell programs are preserved in neonatal BM HSPCs, which reside in a niche expressing HSC supportive factors distinct from those seen in adults. Collectively, our results provide important insights into the factors shaping hematopoiesis during this understudied window of hematopoietic development.
Relatively little is known about the first hematopoietic stem and progenitor cells to arrive in the fetal bone marrow. Here they characterize the frequency, function, and molecular identity of fetal BM HSPCs and their bone marrow niche, and show that most BM HSPCs have little hematopoietic function until birth.
Journal Article