Objective: Diaphragmatic weakness and acute respiratory failure are common in sepsis. Nuclear factor-κB acts as a general coordinator of the systemic inflammatory response, but its role within the diaphragm itself during sepsis is unknown. We investigated the potential protective effect upon the diaphragm of inhibiting nuclear factor-κB only within muscle fibers during acute endotoxemia.
Design: Prospective study in experimental animals.
Setting: University research laboratory.
Interventions: Wild-type and transgenic (muscle-specific IκBα super-repressor) mice with skeletal muscle-specific inhibition of the classical nuclear factor-κB pathway were subjected to acute endotoxemia. Muscle-specific ubiquitin ligases (muscle RING-finger protein 1 and atrogin-1), caspase-3 activity, inhibitor of apoptosis proteins, proinflammatory cytokines (interleukin-1β, monocyte chemoattractant protein-1, and tumor necrosis factor-α), and diaphragmatic contractility were evaluated after 24 hours.
Measurements And Main Results: In wild-type mice, endotoxemia significantly increased proinflammatory cytokines (fold-change messenger RNA: interleukin-1β = 7.6, monocyte chemoattractant protein-1 = 15.3, and tumor necrosis factor-α = 2.2) and proteolysis effectors (fold-change messenger RNA: muscle RING-finger protein 1 = 5.7, atrogin-1 = 2.8; caspase-3 activity elevated by 28%) in the diaphragm, while reducing its force-generating capacity by 38%. In nonendotoxemic muscle-specific IκBα super-repressor diaphragms, caspase-3 activity was unexpectedly increased by 40% above basal wild-type levels and inhibitors of apoptosis proteins were down-regulated, but force production remained normal. In muscle-specific IκBα super-repressor mice subjected to endotoxemia, proinflammatory cytokines, muscle RING-finger protein 1, and atrogin-1 were not significantly increased above their basal levels, and diaphragmatic weakness and further increases in caspase-3 activity were completely prevented.
Conclusions: These results suggest that nuclear factor-κB signaling within skeletal muscle fibers is a key pathway leading to diaphragmatic weakness during acute endotoxemia, most likely via effects on multiple inflammatory mediators. In addition, inhibition of nuclear factor-κB signaling within diaphragm muscle fibers has complex effects on caspase-3 activation, which could have implications for the treatment of sepsis-induced diaphragmatic dysfunction.
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http://dx.doi.org/10.1097/CCM.0000000000000407 | DOI Listing |
Neurology
February 2025
Department of Medicine and Geriatrics, Tuen Mun Hospital, Hong Kong, People's Republic of China.
Background And Objectives: Mitochondrial disorders are multiorgan disorders resulting in significant morbidity and mortality. We aimed to characterize death-associated factors in an international cohort of deceased individuals with mitochondrial disorders.
Methods: This cross-sectional multicenter observational study used data provided by 26 mitochondrial disease centers from 8 countries from January 2022 to March 2023.
Proc Natl Acad Sci U S A
February 2025
SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon 16419, Republic of Korea.
The design of organic-peptide hybrids has the potential to combine our vast knowledge of protein design with small molecule engineering to create hybrid structures with complex functions. Here, we describe the computational design of a photoswitchable Ca-binding organic-peptide hybrid. The designed molecule, designated Ca-binding switch (CaBS), combines an EF-hand motif from classical Ca-binding proteins such as calmodulin with a photoswitchable group that can be reversibly isomerized between a spiropyran (SP) and merocyanine (MC) state in response to different wavelengths of light.
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January 2025
President, American Nuclear Society, Washington, DC, USA.
Science
January 2025
Program on Science and Global Security, Princeton University, Princeton, NJ, USA.
Science
January 2025
Department of Genome Sciences, University of Washington, Seattle, WA, USA.
Studying the functional consequences of structural variants (SVs) in mammalian genomes is challenging because (i) SVs arise much less commonly than single-nucleotide variants or small indels and (ii) methods to generate, map, and characterize SVs in model systems are underdeveloped. To address these challenges, we developed Genome-Shuffle-seq, a method that enables the multiplex generation and mapping of thousands of SVs (deletions, inversions, translocations, and extrachromosomal circles) throughout mammalian genomes. We also demonstrate the co-capture of SV identity with single-cell transcriptomes, facilitating the measurement of SV impact on gene expression.
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