Publications by authors named "James Lo"

The immune system coordinates the response to cardiac injury and controls regenerative and fibrotic scar outcomes in the heart and subsequent chronic low-grade inflammation associated with heart failure. Adult mice and humans lack the ability to fully recover while adult zebrafish spontaneously regenerate after heart injury. Here we profile the inflammatory response to heart cryoinjury in zebrafish and coronary artery ligation in mouse using single cell transcriptomics.

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Pancreatic β cell dysfunction is critical to the development of type 2 diabetes (T2D). We show that the complement receptor C3aR1 on β cells plays an essential role in maintaining β cell homeostasis, especially under the metabolic duress of obesity and T2D. Mice with β cell specific deletion of have worse glucose tolerance, lower insulin levels, and decreased β cell mass.

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  • * Researchers created a G406R knockin mouse model that exhibits TS features, including hypoglycemia, but surprisingly does not show increased beta cell activity or hyperinsulinism.
  • * The study unveils alternative mechanisms for hypoglycemia, such as impaired hormone responses and disrupted hypothalamic regulation of glucose levels, enhancing our understanding of how mutant channels impact TS.
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Study Design: Analysis of data from two cohorts of Spinal Cord Injury Model Systems Database (SCIMS) participants, pre-pandemic (2017-2019,  = 6368) and during pandemic (2020,  = 1889).

Objectives: To examine differences in substance use during the pandemic compared to the years prior to the pandemic.

Setting: 19 SCIMS Centers.

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  • Diffusion tensor imaging (DTI) is an MRI technique used to study microstructural features of skeletal muscle related to its function.
  • A study examining DTI measurements and histological data from rat rotator cuff muscles found negligible correlations between DTI metrics and various histological characteristics like muscle fiber size and cross-sectional area.
  • The results highlight the difficulty of validating DTI against histology due to challenges in data co-localization, high-quality histological requirements, and the measurement scales used, suggesting the need for more research with improved imaging conditions.
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Compositional changes can occur in the osteochondral junction (OCJ) during the early stages and progressive disease evolution of knee osteoarthritis (OA). However, conventional magnetic resonance imaging (MRI) sequences are not able to image these regions efficiently because of the OCJ region's rapid signal decay. The development of new sequences able to image and quantify OCJ region is therefore highly desirable.

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  • Researchers developed a detailed 3D MRI protocol using four different imaging techniques to analyze key brain components related to tissue and fluid, targeting both healthy individuals and MS patients.
  • The protocol successfully quantified brain-related metrics such as macromolecular content and different types of water, revealing significant differences in these metrics between MS lesions and healthy brain regions.
  • The study shows that this advanced MRI method can reliably assess the brain's structure and could be valuable for understanding neuroinflammatory and neurodegenerative diseases.
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Purpose: The semisolid myelin sheath has very fast transverse relaxation and is invisible to conventional MRI sequences. UTE sequences can detect signal from myelin. The major challenge is the concurrent detection of various water components.

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  • Metabolic dysfunction-associated steatotic liver disease (MASLD) is increasingly common alongside obesity and type 2 diabetes, with a link to immune responses involving complement proteins and macrophages.
  • The study investigates the role of the complement 3a receptor (C3aR1) in macrophages, particularly in the liver's Kupffer cells, by creating mouse models lacking this receptor.
  • Results show that deleting C3aR1 in macrophages or Kupffer cells doesn't significantly impact liver conditions like steatosis, inflammation, or fibrosis in the context of a MASLD-inducing diet.
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Thermogenesis in beige/brown adipose tissues can be leveraged to combat metabolic disorders such as type 2 diabetes and obesity. The complement system plays pleiotropic roles in metabolic homeostasis and organismal energy balance with canonical effects on immune cells and noncanonical effects on nonimmune cells. The adipsin/C3a/C3a receptor 1 (C3aR1) pathway stimulates insulin secretion and sustains pancreatic β cell mass.

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Background: Myelin water imaging (MWI) is a myelin-specific technique, which has great potential for the assessment of demyelination and remyelination. This study develops a new MWI method, which employs a short repetition time adiabatic inversion recovery (STAIR) technique in combination with a commonly used fast spin echo (FSE) sequence and provides quantification of myelin water (MW) fractions.

Method: Whole-brain MWI was performed using the short repetition time adiabatic inversion recovery prepared-fast spin echo (STAIR-FSE) technique on eight healthy volunteers (mean age: 38±14 years, four-males) and seven patients with multiple sclerosis (MS) (mean age: 53.

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Excessive adiposity in obesity is a significant risk factor for development of type 2 diabetes (T2D), nonalcoholic fatty liver disease, and other cardiometabolic diseases. An unhealthy expansion of adipose tissue (AT) results in reduced adipogenesis, increased adipocyte hypertrophy, adipocyte hypoxia, chronic low-grade inflammation, increased macrophage infiltration, and insulin resistance. This ultimately culminates in AT dysfunction characterized by decreased secretion of antidiabetic adipokines such as adiponectin and adipsin and increased secretion of proinflammatory prodiabetic adipokines including RBP4 and resistin.

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Purpose: To investigate the feasibility and application of a novel imaging technique, a three-dimensional dual adiabatic inversion recovery prepared ultrashort echo time (3D DIR-UTE) sequence, for high contrast assessment of cartilaginous endplate (CEP) imaging with head-to-head comparisons between other UTE imaging techniques.

Method: The DIR-UTE sequence employs two narrow-band adiabatic full passage (AFP) pulses to suppress signals from long T water (e.g.

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Objective: Glucose-dependent insulinotropic polypeptide (GIP) has a role in controlling postprandial metabolic tone. In humans, a GIP receptor (GIPR) variant (Q354, rs1800437) is associated with a lower body mass index (BMI) and increased risk for Type 2 Diabetes. To better understand the impacts of GIPR-Q354 on metabolism, it is necessary to study it in an isogeneic background to the predominant GIPR isoform, E354.

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Introduction: Numerous techniques for myelin water imaging (MWI) have been devised to specifically assess alterations in myelin. The biomarker employed to measure changes in myelin content is known as the myelin water fraction (MWF). The short TR adiabatic inversion recovery (STAIR) sequence has recently been identified as a highly effective method for calculating MWF.

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Cancer alters the function of multiple organs beyond those targeted by metastasis. Here we show that inflammation, fatty liver and dysregulated metabolism are hallmarks of systemically affected livers in mouse models and in patients with extrahepatic metastasis. We identified tumour-derived extracellular vesicles and particles (EVPs) as crucial mediators of cancer-induced hepatic reprogramming, which could be reversed by reducing tumour EVP secretion via depletion of Rab27a.

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The immune system coordinates the response to cardiac injury and is known to control regenerative and fibrotic scar outcomes in the heart and subsequent chronic low-grade inflammation associated with heart failure. Here we profiled the inflammatory response to heart injury using single cell transcriptomics to compare and contrast two experimental models with disparate outcomes. We used adult mice, which like humans lack the ability to fully recover and zebrafish which spontaneously regenerate after heart injury.

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The pancreatic islets are composed of discrete hormone-producing cells that orchestrate systemic glucose homeostasis. Here we identify subsets of beta cells using a single-cell transcriptomic approach. One subset of beta cells marked by high CD63 expression is enriched for the expression of mitochondrial metabolism genes and exhibits higher mitochondrial respiration compared with CD63 beta cells.

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The Coronavirus Disease 2019 (COVID-19) pandemic renewed interest in infectious aerosols and reducing risk of airborne respiratory pathogen transmission, prompting development of devices to protect healthcare workers during airway procedures. However, there are no standard methods for assessing the efficacy of particle containment with these protective devices. We designed and built an aerosol bio-containment device (ABCD) to contain and remove aerosol via an external suction system and tested the aerosol containment of the device in an environmental chamber using a novel, quantitative assessment method.

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Rising rates of obesity are intricately tied to the type 2 diabetes epidemic. The adipose tissues can play a central role in protection against or triggering metabolic diseases through the secretion of adipokines. Many adipokines may improve peripheral insulin sensitivity through a variety of mechanisms, thereby indirectly reducing the strain on beta cells and thus improving their viability and functionality.

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Preservation and expansion of β-cell mass is a therapeutic goal for diabetes. Here we show that the hyperactive isoform of carbohydrate response-element binding protein (ChREBPβ) is a nuclear effector of hyperglycemic stress occurring in β-cells in response to prolonged glucose exposure, high-fat diet, and diabetes. We show that transient positive feedback induction of ChREBPβ is necessary for adaptive β-cell expansion in response to metabolic challenges.

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Individuals infected with SARS-CoV-2 who also display hyperglycemia suffer from longer hospital stays, higher risk of developing acute respiratory distress syndrome (ARDS), and increased mortality. Nevertheless, the pathophysiological mechanism of hyperglycemia in COVID-19 remains poorly characterized. Here, we show that hyperglycemia is similarly prevalent among patients with ARDS independent of COVID-19 status.

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