Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 6 de 6
Filter
Add more filters










Database
Type of study
Language
Publication year range
1.
Cureus ; 16(3): e56486, 2024 Mar.
Article in English | MEDLINE | ID: mdl-38638768

ABSTRACT

Medical students rotating through emergency departments as part of their clinical education are typically evaluated using an on-shift evaluation tool. The National Clinical Assessment Tool for Medical Students in the Emergency Department (NCAT-EM) is the current standard of evaluation for medical students in the emergency department, regardless of level of training. This study aims to evaluate whether the NCAT-EM can detect differences in skill levels between third-year medical students (MS3s) and fourth-year medical students (MS4s) rotating at a level 1 trauma center and teaching institution. These authors hypothesized that MS4s should outperform MS3s across all assessment domains given their additional training. A total of 930 performance evaluations were gathered for MS3 and MS4 rotating between May 2022 and June 2023. There were 321 evaluations of MS3s and 609 evaluations of MS4s. Across the six assessment domains, MS4s had statistically significant higher performances in two domains - namely emergency recognition and management (fully entrustable: 37.4% vs. 23.8% (p = 0.03)) and communication (fully entrustable: 46.2% vs. 33.6% (p = 0.03)). These findings indicate that the use of the NCAT-EM at this institution reliably differentiated between MS3s and MS4s in these two assessment domains. There were trends suggesting MS4s outperform MS3s in the other four domains, which did not rise to the level of statistical significance, but are consistent with prior validation studies of the NCAT.

2.
bioRxiv ; 2023 Jun 14.
Article in English | MEDLINE | ID: mdl-37398272

ABSTRACT

The post-translational modification (PTM) of proteins by O-linked ß-N-acetyl-D-glucosamine (O-GlcNAcylation) is widespread across the proteome during the lifespan of all multicellular organisms. However, nearly all functional studies have focused on individual protein modifications, overlooking the multitude of simultaneous O-GlcNAcylation events that work together to coordinate cellular activities. Here, we describe Networking of Interactors and SubstratEs (NISE), a novel, systems-level approach to rapidly and comprehensively monitor O-GlcNAcylation across the proteome. Our method integrates affinity purification-mass spectrometry (AP-MS) and site-specific chemoproteomic technologies with network generation and unsupervised partitioning to connect potential upstream regulators with downstream targets of O-GlcNAcylation. The resulting network provides a data-rich framework that reveals both conserved activities of O-GlcNAcylation such as epigenetic regulation as well as tissue-specific functions like synaptic morphology. Beyond O-GlcNAc, this holistic and unbiased systems-level approach provides a broadly applicable framework to study PTMs and discover their diverse roles in specific cell types and biological states.

3.
Nat Neurosci ; 26(1): 12-26, 2023 01.
Article in English | MEDLINE | ID: mdl-36536241

ABSTRACT

Iron dysregulation has been implicated in multiple neurodegenerative diseases, including Parkinson's disease (PD). Iron-loaded microglia are frequently found in affected brain regions, but how iron accumulation influences microglia physiology and contributes to neurodegeneration is poorly understood. Here we show that human induced pluripotent stem cell-derived microglia grown in a tri-culture system are highly responsive to iron and susceptible to ferroptosis, an iron-dependent form of cell death. Furthermore, iron overload causes a marked shift in the microglial transcriptional state that overlaps with a transcriptomic signature found in PD postmortem brain microglia. Our data also show that this microglial response contributes to neurodegeneration, as removal of microglia from the tri-culture system substantially delayed iron-induced neurotoxicity. To elucidate the mechanisms regulating iron response in microglia, we performed a genome-wide CRISPR screen and identified novel regulators of ferroptosis, including the vesicle trafficking gene SEC24B. These data suggest a critical role for microglia iron overload and ferroptosis in neurodegeneration.


Subject(s)
Ferroptosis , Induced Pluripotent Stem Cells , Iron Overload , Parkinson Disease , Humans , Induced Pluripotent Stem Cells/metabolism , Iron/metabolism , Iron Overload/metabolism , Microglia/metabolism , Parkinson Disease/genetics
4.
J Neurosci ; 40(47): 9137-9147, 2020 11 18.
Article in English | MEDLINE | ID: mdl-33051352

ABSTRACT

Amyotrophic lateral sclerosis (ALS) is a fatal neuromuscular disease characterized by motor neuron (MN) death. Lipid dysregulation manifests during disease; however, it is unclear whether lipid homeostasis is adversely affected in the in the spinal cord gray matter (GM), and if so, whether it is because of an aberrant increase in lipid synthesis. Moreover, it is unknown whether lipid dysregulation contributes to MN death. Here, we show that cholesterol ester (CE) and triacylglycerol levels are elevated several-fold in the spinal cord GM of male sporadic ALS patients. Interestingly, HMG-CoA reductase, the rate-limiting enzyme in cholesterol synthesis, was reduced in the spinal cord GM of ALS patients. Increased cytosolic phospholipase A2 activity and lyso-phosphatidylcholine (Lyso-PC) levels in ALS patients suggest that CE accumulation was driven by acyl group transfer from PC to cholesterol. Notably, Lyso-PC, a byproduct of CE synthesis, was toxic to human MNs in vitro Elevations in CE, triacylglycerol, and Lyso-PC were also found in the spinal cord of SOD1G93A mice, a model of ALS. Similar to ALS patients, a compensatory downregulation of cholesterol synthesis occurred in the spinal cord of SOD1G93A mice; levels of sterol regulatory element binding protein 2, a transcriptional regulator of cholesterol synthesis, progressively declined. Remarkably, overexpressing sterol regulatory element binding protein 2 in the spinal cord of normal mice to model CE accumulation led to ALS-like lipid pathology, MN death, astrogliosis, paralysis, and reduced survival. Thus, spinal cord lipid dysregulation in ALS likely contributes to neurodegeneration and developing therapies to restore lipid homeostasis may lead to a treatment for ALS.SIGNIFICANCE STATEMENT Neurons that control muscular function progressively degenerate in patients with amyotrophic lateral sclerosis (ALS). Lipid dysregulation is a feature of ALS; however, it is unclear whether disrupted lipid homeostasis (i.e., lipid cacostasis) occurs proximal to degenerating neurons in the spinal cord, what causes it, and whether it contributes to neurodegeneration. Here we show that lipid cacostasis occurs in the spinal cord gray matter of ALS patients. Lipid accumulation was not associated with an aberrant increase in synthesis or reduced hydrolysis, as enzymatic and transcriptional regulators of lipid synthesis were downregulated during disease. Last, we demonstrated that genetic induction of lipid cacostasis in the CNS of normal mice was associated with ALS-like lipid pathology, astrogliosis, neurodegeneration, and clinical features of ALS.


Subject(s)
Amyotrophic Lateral Sclerosis/pathology , Lipid Metabolism , Amyotrophic Lateral Sclerosis/metabolism , Animals , Cell Death , Cholesterol Esters/metabolism , Gray Matter/metabolism , Humans , Lysophosphatidylcholines/metabolism , Male , Mice , Mice, Transgenic , Motor Neurons/pathology , Receptors, G-Protein-Coupled/genetics , Receptors, Phospholipase A2/metabolism , Spinal Cord/metabolism , Superoxide Dismutase-1/genetics , Triglycerides/metabolism
5.
Proc Natl Acad Sci U S A ; 113(52): 15120-15125, 2016 12 27.
Article in English | MEDLINE | ID: mdl-27956640

ABSTRACT

O-GlcNAc glycosylation (or O-GlcNAcylation) is a dynamic, inducible posttranslational modification found on proteins associated with neurodegenerative diseases such as α-synuclein, amyloid precursor protein, and tau. Deletion of the O-GlcNAc transferase (ogt) gene responsible for the modification causes early postnatal lethality in mice, complicating efforts to study O-GlcNAcylation in mature neurons and to understand its roles in disease. Here, we report that forebrain-specific loss of OGT in adult mice leads to progressive neurodegeneration, including widespread neuronal cell death, neuroinflammation, increased production of hyperphosphorylated tau and amyloidogenic Aß-peptides, and memory deficits. Furthermore, we show that human cortical brain tissue from Alzheimer's disease patients has significantly reduced levels of OGT protein expression compared with cortical tissue from control individuals. Together, these studies indicate that O-GlcNAcylation regulates pathways critical for the maintenance of neuronal health and suggest that dysfunctional O-GlcNAc signaling may be an important contributor to neurodegenerative diseases.


Subject(s)
Acetylglucosamine/chemistry , Glycosylation , N-Acetylglucosaminyltransferases/chemistry , Neurons/chemistry , Prosencephalon/cytology , Alzheimer Disease/metabolism , Alzheimer Disease/pathology , Amyloid beta-Peptides/metabolism , Animals , Brain Mapping , Crosses, Genetic , Female , Hippocampus/metabolism , Humans , Inflammation , Male , Memory Disorders , Mice , Mice, Inbred C57BL , Mice, Knockout , Neurodegenerative Diseases/pathology , Neuroglia/metabolism , Neurons/pathology , Phosphorylation , Prosencephalon/metabolism , Signal Transduction , tau Proteins/metabolism
6.
Mol Biosyst ; 12(6): 1756-9, 2016 05 24.
Article in English | MEDLINE | ID: mdl-27063346

ABSTRACT

The post-translational modification of serine or threonine residues of proteins with a single N-acetylglucosamine monosaccharide (O-GlcNAcylation) is essential for cell survival and function. However, relatively few O-GlcNAc modification sites have been mapped due to the difficulty of enriching and detecting O-GlcNAcylated peptides from complex samples. Here we describe an improved approach to quantitatively label and enrich O-GlcNAcylated proteins for site identification. Chemoenzymatic labelling followed by copper(i)-catalysed azide-alkyne cycloaddition (CuAAC) installs a new mass spectrometry (MS)-compatible linker designed for facile purification of O-GlcNAcylated proteins from cell lysates. The linker also allows subsequent quantitative release of O-GlcNAcylated proteins for downstream MS analysis. We validate the approach by unambiguously identifying several established O-GlcNAc sites on the proteins α-crystallin and O-GlcNAc transferase (OGT), as well as discovering new, previously unreported sites on OGT. Notably, these novel sites on OGT lie in key functional domains of the protein, underscoring how this site identification method may reveal important biological insights into protein activity and regulation.


Subject(s)
Acetylglucosamine/chemistry , Acetylglucosamine/metabolism , N-Acetylglucosaminyltransferases/metabolism , Protein Processing, Post-Translational , Chromatography, Liquid , Glycosylation , Humans , Mass Spectrometry , Staining and Labeling
SELECTION OF CITATIONS
SEARCH DETAIL
...