Mitochondrial dysfunction contributes to cardiac pathologies. Barriers to new therapies include an incomplete understanding of underlying molecular culprits and a lack of effective mitochondria-targeted medicines. Here, we test the hypothesis that the cardiolipin-binding peptide elamipretide, a clinical-stage compound under investigation for diseases of mitochondrial dysfunction, mitigates impairments in mitochondrial structure-function observed after rat cardiac ischemia-reperfusion. Respirometry with permeabilized ventricular fibers indicates that ischemia-reperfusion induced decrements in the activity of complexes I, II, and IV are alleviated with elamipretide. Serial block face scanning electron microscopy used to create 3D reconstructions of cristae ultrastructure reveals that disease-induced fragmentation of cristae networks are improved with elamipretide. Mass spectrometry shows elamipretide did not protect against the reduction of cardiolipin concentration after ischemiareperfusion. Finally, elamipretide improves biophysical properties of biomimetic membranes by aggregating cardiolipin. The data suggest mitochondrial structure-function are interdependent and demonstrate elamipretide targets mitochondrial membranes to sustain cristae networks and improve bioenergetic function.
Docosahexaenoic acid (DHA, 22:6) is an n-3 polyunsaturated fatty acid (n-3 PUFA) that influences immunological, metabolic, and neurological responses through complex mechanisms. One structural mechanism by which DHA exerts its biological effects is through its ability to modify the physical organization of plasma membrane signaling assemblies known as sphingomyelin/cholesterol (SM/chol)-enriched lipid rafts. Here we studied how DHA acyl chains esterified in the sn-2 position of phosphatidylcholine (PC) regulate the formation of raft and non-raft domains in mixtures with SM and chol on differing size scales. Coarse grained molecular dynamics simulations showed that 1-palmitoyl-2-docosahexaenoylphosphatylcholine (PDPC) enhances segregation into domains more than the monounsaturated control, 1-palmitoyl-2-oleoyl-phosphatidylcholine (POPC). Solid state H NMR and neutron scattering experiments provided direct experimental evidence that substituting PDPC for POPC increases the size of raft-like domains on the nanoscale. Confocal imaging of giant unilamellar vesicles with a non-raft fluorescent probe revealed that POPC had no influence on phase separation in the presence of SM/chol whereas PDPC drove strong domain segregation. Finally, monolayer compression studies suggest that PDPC increases lipid-lipid immiscibility in the presence of SM/chol compared to POPC. Collectively, the data across model systems provide compelling support for the emerging model that DHA acyl chains of PC lipids tune the size of lipid rafts, which has potential implications for signaling networks that rely on the compartmentalization of proteins within and outside of rafts.
Cardiolipin (CL) is an anionic phospholipid mainly located in the inner mitochondrial membrane, where it helps regulate bioenergetics, membrane structure, and apoptosis. Localized, phase-segregated domains of CL are hypothesized to control mitochondrial inner membrane organization. However, the existence and underlying mechanisms regulating these mitochondrial domains are unclear. Here, we first isolated detergent-resistant cardiac mitochondrial membranes that have been reported to be CL-enriched domains. Experiments with different detergents yielded only nonspecific solubilization of mitochondrial phospholipids, suggesting that CL domains are not recoverable with detergents. Next, domain formation was investigated in biomimetic giant unilamellar vesicles (GUVs) and newly synthesized giant mitochondrial vesicles (GMVs) from mouse hearts. Confocal fluorescent imaging revealed that introduction of cytochrome into membranes promotes macroscopic proteolipid domain formation associated with membrane morphological changes in both GUVs and GMVs. Domain organization was also investigated after lowering tetralinoleoyl-CL concentration and substitution with monolyso-CL, two common modifications observed in cardiac pathologies. Loss of tetralinoleoyl-CL decreased proteolipid domain formation in GUVs, because of a favorable Gibbs-free energy of lipid mixing, whereas addition of monolyso-CL had no effect on lipid mixing. Moreover, murine GMVs generated from cardiac acyl-CoA synthetase-1 knockouts, which have remodeled CL acyl chains, did not perturb proteolipid domains. Finally, lowering the tetralinoleoyl-CL content had a stronger influence on the oxidation status of cytochrome than did incorporation of monolyso-CL. These results indicate that proteolipid domain formation in the cardiac mitochondrial inner membrane depends on tetralinoleoyl-CL concentration, driven by underlying lipid-mixing properties, but not the presence of monolyso-CL.
Background: Analgesic guidelines are lacking for most operative pediatric fractures, and little is known about postdischarge opioid use or pain control. We hypothesized that opioid/acetaminophen/non-steroidal anti-inflammatory drugs (NSAID) prescribing would vary, pain would be well controlled, and postdischarge opioid use would be low. Methods: This prospective cohort study included nonpolytraumatized patients aged 17 years and below with operative fractures at a level 1 trauma center from August 1, 2019 to March 31, 2021. Supracondylar humerus fractures were excluded since they have been studied extensively. Information regarding injury/surgery/ analgesics were collected. Discharged patients were called on postoperative days (POD) 1/3/5. Parents/guardians were asked about analgesic use and pain over the preceding 2 days. Complications, pain control, and opioid refills were recorded after first follow-up. Results: All 100 eligible patients were included. Mean age was 10.1 years (range: 1.8 to 17.8 y). Common fracture types were humeral condyle/epicondyle (28%), radius/ulna (15%), and femoral shaft (13%). Opioids were prescribed to 95% of patients with mean 14 doses (range: 2 to 45). Acetaminophen/NSAIDs were prescribed to 74% and 60% of patients, respectively. Eleven patients were excluded from telephone follow-up (7 non-English speaking, 3 prohibitive social situations, 1 inpatient POD1 to 5). Telephone follow-up was completed for 87/89 eligible patients (98%). Mean pain scores declined from 3.7/10 POD1 to 2.4/10 POD5. Opioids were taken by 50% POD1, 20% POD5. Acetaminophen/NSAID was given before opioid 82% of the time. By POD5, mean total doses of opioid taken postdischarge was 2.3; mean proportion of prescribed opioid doses taken was 22%; and 97% of patients took ≤ 8 opioid doses postdischarge. Two patients were evaluated early due to poor pain control which improved with cast changes. Pain was well controlled or absent at follow-up in 97% of patients.Conclusions: Pain is consistently well controlled after operative pediatric fractures. Nearly all were prescribed opioids, while acetaminophen/NSAIDs were inconsistently prescribed and used. Opioid prescriptions are written for 4 to 5 times the amount needed. Prescribing ≤ 8 doses of opioid is adequate for acute pain through POD5 in 97% of patients. Poorly controlled pain should prompt early evaluation for possible complications.
State EMS protocols for fluid administration for hypotensive trauma patients vary in regard to SBP goal, fluid dose, and fluid type. Clinical trials to determine the optimal use of intravenous fluids for hypotensive trauma patients are needed to define the optimal approach.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.