Littérature scientifique sur le sujet « 895.6/12 »

Abstract Background Thromboelastographic measures of clot strength increase early after injury, portending higher risks for thromboembolic complications during recovery. Understanding the specific role of platelets is challenging due to a lack of clinically relevant measures of platelet function. Platelet mitochondrial respirometry may provide insight to global platelet function, but has not yet been correlated with functional coagulation studies. Methods Wistar rats underwent anesthesia and either immediate sacrifice for baseline values [n = 6] or (1) bilateral hindlimb orthopedic injury [n = 12], versus (2) sham anesthesia [n = 12] with terminal phlebotomy/hepatectomy after 24 hours. High resolution respirometry was used to measure basal respiration, mitochondrial leak, maximal oxidative phosphorylation, and Complex IV activity in intact platelets; Complex-I and Complex-II driven respiration was measured in isolated liver mitochondria. Results were normalized to platelet number and protein mass, respectively. Citrated native thromboelastography (TEG) was performed in triplicate. Results Citrated native TEG maximal amplitude (MA) was significantly higher (81.0 ± 3.0 vs. 73.3 ± 3.5 mm, p < 0.001) in trauma compared to sham rats 24 hours after injury. Intact platelets from injured rats had higher basal oxygen consumption (17.7 ± 2.5 vs. 15.1 ± 3.2 pmol/s*108 cells, p = 0.045), with similar trends in mitochondrial leak rate (p = 0.19) when compared to sham animals. Overall, platelet basal respiration significantly correlated with TEG-MA (r = 0.44, p = 0.034). As a control for sex-dependent systemic mitochondrial differences, females displayed higher liver mitochondria Complex-I driven respiration (895.6 ± 123.7 vs. 622.1 ± 48.7 mmol e-/min/mg protein, p = 0.02); as a control for systemic mitochondrial effects of injury, no liver mitochondrial respiration differences were seen. Conclusions Platelet mitochondrial basal respiration is increased after injury and correlates with clot strength in this rodent hindlimb fracture model. Several mitochondrial-targeted therapeutics exist in common use that are underexplored but hold promise as potential antithrombotic adjuncts that can be sensitively evaluated in this preclinical model.

BackgroundSepsis-induced muscle atrophy leads to prolonged physical dysfunction. Although the interaction of muscle atrophy and macrophage has been reported in sepsis, the role of neutrophils in muscle atrophy has not been thoroughly investigated. This study sought to investigate the long-term changes in muscle-localized neutrophils after sepsis induction and their possible role in sepsis.MethodsSepsis was induced in seven-week-old male C57BL/6J mice 8-12 (cecal slurry [CS] model) via intraperitoneal injection of 1 mg/g cecal slurry. The percentage change in body weight and grip strength was evaluated. The tibialis anterior muscles were dissected for microscopic examination of the cross-sectional area of myofibers or Fluorescence-activated cell sorting (FACS) analysis of immune cells. These changes were evaluated in the following conditions: (1) Longitudinal change until day 61, (2) CS concentration-dependent change on day 14 at the low (0.3 mg/g), middle (1.0 mg/g), and high (2.0 mg/g) concentrations, and (3) CS mice on day 14 treated with an anti-Ly6G antibody that depletes neutrophils.ResultsBody weight and grip strength were significantly lower in the CS model until day 61 (body weight: 123.1% ± 1.8% vs. 130.3% ± 2.5%, p = 0.04; grip strength: 104.5% ± 3.8% vs. 119.3% ± 5.3%, p = 0.04). Likewise, cross-sectional muscle area gradually decreased until day 61 from the CS induction (895.6 [606.0–1304.9] μm2 vs. 718.8 [536.2–937.0] μm2, p &lt; 0.01). The number of muscle-localized neutrophils increased from 2.3 ± 0.6 cell/mg on day 0 to 22.2 ± 13.0 cell/mg on day 14, and decreased thereafter. In terms of CS concentration–dependent change, cross-sectional area was smaller (484.4 ± 221.2 vs. 825.8 ± 436.2 μm2 [p &lt; 0.001]) and grip strength was lower (71.4% ± 12.8% vs. 116.3% ± 7.4%, p = 0.01) in the CS High group compared with the control, with increased neutrophils (p = 0.03). Ly6G-depleted mice demonstrated significant increase of muscle cross-sectional area and grip strength compared with control mice (p &lt; 0.01).ConclusionsSepsis causes infiltration of neutrophils in muscles, leading to muscle atrophy and weakness. Depletion of neutrophils in muscle reverses sepsis-induced muscle atrophy and weakness. These results suggest that neutrophils may play a critical role in sepsis-induced muscle atrophy and weakness.

None of the many previous animal models of NAFLD/NASH, whether genetic mouse models or aberrant dietary challenges, replicate or fully reflect either the metabolic pathophysiology or the histopathology of patients with NAFLD/NASH. We report for the first time the development and characterization of NASH in middle‐aged naturally overweight nonhuman primates. This colony has been maintained continuously on a healthy low fat high fiber diet and by all parameters, it is clear that these rhesus monkeys have developed the same disease as develops so commonly in humans.MethodsNAFLD/NASH histopathology was examined in 37 male rhesus monkeys (7–20yrs, 7–18kg; 25 of which were significantly overweight >12 kg). These nonhuman primates have exhibited in detail the characteristics of the metabolic syndrome as seen in humans, including normoglycemia, hyperinsulinemia, insulin resistance, hypertension, and dyslipidemia, together with additional circulating biomarkers.ResultsBy ultrasound evaluation of the 37 monkeys, 6 were identified to be normal with no steatosis (<5%); 12 had mild steatosis (5–10%) and 19 had moderate steatosis (10–30%). Dual‐energy CT (DECT) was used to quantify liver fat content. DECT quantified 6, 12, and 19 monkeys into the normal group <5% fat, the mild group with 5–10% fat, and the moderate group with 10 to 30% fat. The mild and moderate groups had significantly higher body weights (p<0.001) and higher C‐peptide levels than the normal group (p<0.01). In 24 of these 37 monkeys, liver needle biopsies were performed and evaluated by standard stains. Separately and blindly, the NAFLD Activity Score (NAS; by H&E) and then the fibrosis score (by Masson) were determined for each biopsy specimen. All 6 of the monkeys that were normal by DECT had normal NAS scores. 50% of the monkeys that were in the mild group all had NAS scores of 4; among the 10 monkeys in the mod group that were biopsied, 9 of 10 had NASH (5 with NAS scores of 4, and 4 with NAS scores of 5–6) and 1 had simple steatosis (SS). Masson results showed that of the 4 with NAS scores of 5–6, 3 were in stages 2–3, and 1 was in stage 1a. Among the 5 with NAS score of 4, 4 were in 0–1c stage. The 4 in the mild group with NAS scores of 3–4 wee in 1c‐3 stages. SS cases were in the 1a–1c stage. In conclusion, DECT is important for noninvasive liver fat quantification in obese patients and the NAFLD monkey model shows the same specific liver pathology and circulating biomarkers as humans.ConclusionsWe conclude that this nonhuman primate model, permitting both repeated liver biopsies and imaging studies, provides new opportunities to understand the pathogenesis as well as to examine in detail (with sequential repeated liver biopsies and longitudinal metabolic biomarkers) both the progression of the disease and its response to new therapeutic agents.