Asuka Kasai

Exendin-4 ameliorates cardiac ischemia/reperfusion injury via caveolae and caveolins-3

BackgroundExendin-4, an exogenous glucagon-like peptide-1 receptor (GLP-1R) agonist, protects the heart from ischemia/reperfusion injury. However, the mechanisms for this protection are poorly understood. Caveolae, sarcolemmal invaginations, and caveolins, scaffolding proteins in caveolae, localize molecules involved in cardiac protection. We tested the hypothesis that caveolae and caveolins are essential for exendin-4 induced cardiac protection using in vitro and in vivo studies in control and caveolin-3 (Cav-3) knockout mice (Cav-3 KO).MethodsMyocytes were treated with exendin-4 and then incubated with methyl-β-cyclodextrin (MβCD) to disrupt caveolae formation. This was then followed by simulated ischemia/reperfusion (SI/R). In addition, cardiac protection in vivo was assessed by measuring infarct size and cardiac troponin levels.ResultsExendin-4 protected cardiac myocytes (CM) from SI/R [35.6 ± 12.6% vs. 64.4 ± 18.0% cell death, P = 0.034] and apoptosis but this protection was abolished by MβCD (71.8 ± 10.8% cell death, P = 0.004). Furthermore, Cav-3/GLP-1R co-localization was observed and membrane fractionation by sucrose density gradient centrifugation of CM treated with MβCD  + exendin-4 revealed that buoyant (caveolae enriched) fractions decreased Cav-3 compared to CM treated with exendin-4 exclusively. Furthermore, exendin-4 induced a reduction in infarct size and cardiac troponin relative to control (infarct size: 25.1 ± 8.2% vs. 41.4 ± 4.1%, P < 0.001; troponin: 36.9 ± 14.2 vs. 101.1 ± 22.3 ng/ml, P < 0.001). However, exendin-4 induced cardiac protection was abolished in Cav-3 KO mice (infarct size: 43.0 ± 6.4%, P < 0.001; troponin: 96.8 ± 26.6 ng/ml, P = 0.001).ConclusionsWe conclude that caveolae and caveolin-3 are critical for exendin-4 induced protection of the heart from ischemia/reperfusion injury.

Geranylgeranylacetone protects the heart via caveolae and caveolin-3

AIMS Geranylgeranylacetone (GGA) is commonly utilized to protect the gastric mucosa in peptic ulcer disease. Recently GGA has been shown to protect the myocardium from ischemia/reperfusion by activating heat shock proteins. However, the exact mechanism as to how GGA activates these protective proteins is unknown. Caveolae and caveolin-3 (Cav-3) have been implicated in ischemia, anesthetic, and opioid induced cardiac protection. Given the lipophilic nature of GGA it is our hypothesis that GGA induced cardiac protection requires caveolae and Cav-3. MAIN METHODS We used an in vivo mouse model of ischemia-reperfusion injury and performed biochemical assays in excised hearts. KEY FINDINGS GGA treated control mice revealed increased caveolae formation and caveolin-3 in buoyant fractions, mediating heat shock protein 70 activation. Furthermore, control mice treated with GGA were protected against ischemia/reperfusion injury whereas Cav-3 knockout (Cav-3 KO) mice were not. Troponin levels confirmed myocardial damage. Finally, Cav-3 KO mice treated with GGA were not protected against mitochondrial swelling whereas control mice had significant protection. SIGNIFICANCE This study showed that caveolae and caveolin-3 are essential in facilitating GGA induced cardiac protection by optimizing spatial and temporal signaling to the mitochondria.

Whey Peptide–Based Formulas With ω-3 Fatty Acids Are Protective in Lipopolysaccharide-Mediated Sepsis

BACKGROUND Sepsis and septic shock syndrome are among the leading causes of death in critically ill patients. Lipopolysaccharide (LPS) released by bacteria within the colon may translocate across a compromised epithelium, leading to oxidative stress, inflammation, sepsis, and eventually death. METHODS We examined the effects of a whey-based enteral formula high in cysteine (antioxidant precursor) and the addition of ω-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), against a mouse model of LPS-induced sepsis. Mice were fed either a whey-based diet with EPA-DHA (PAF), a whey-based diet without EPA-DHA (PSTD), or a casein-based control diet (CONT). RESULTS Mice fed PAF or PSTD were protected against LPS-induced weight loss. Whey-based diets suppressed inflammatory cytokine release and oxidative stress damage. Furthermore, PAF and PSTD were able to inhibit autophagy, a mechanism in which the cell recycles damaged organelles. These anti-inflammatory and antioxidative effects of PSTD and PAF resulted in decreased liver inflammation and intestinal damage and promoted protective microbiota within the intestines. CONCLUSIONS These data suggest a clinical role for whey peptide-based diets in promoting healing and recovery in critically ill patients.

Isoflurane-induced postconditioning via mitochondrial calcium-activated potassium channels

PURPOSE Activation of the mitochondrial calcium-activated potassium (mKCa) channel reportedly confers resistance to myocardial ischemic stress. However, the role of the mKCa channel in postconditioning induced by volatile anesthetic remains unclear. METHODS Male Japanese white rabbits underwent coronary artery occlusion for 30 min followed by reperfusion for 3 h. Volatile anesthetic, isoflurane, was administered at 3 min prior to reperfusion for 5 min. Rabbits were injected with the mKCa channel blocker, iberiotoxin, or the mKCa channel opener, NS1619, at 8 min prior to reperfusion. Myocardial infarct size and the area at risk (AAR) were measured at the end of the experiment. RESULTS Isoflurane significantly reduced infarct size (23.0 ± 9.8% of the AAR, P<0.05) compared with the control (44.0 ± 9.1%). Iberiotoxin abolished the cardioprotective impact of isoflurane (43.0 ± 11.6%), while iberiotoxin alone exerted no effect on infarct size (45.0 ± 9.5%). NS1619 and isoflurane/NS1619 both significantly reduced infarct size (21.0 ± 10.3% and 19.0 ± 8.8%, respectively, P<0.05 vs control group), but isoflurane/NS1619 showed no additional benefits compared with isoflurane alone. CONCLUSION These results indicate that activation of the mKCa channel contribute isoflurane-induced postconditioning.

Effectiveness of using non‐invasive continuous arterial pressure monitoring with ClearSight in hemodynamic monitoring during living renal transplantation in a recipient:a case report

We investigated the effectiveness of the ClearSight system for hemodynamic management during kidney transplantation for a recipient. The recipient was to receive a kidney transplant from his mother under general anesthesia. We used continuous noninvasive finger-cuff-based monitoring of blood pressure, provided by the ClearSight system, and stroke volume variation to predict fluid responsiveness. We used of a balanced anesthetic technique and stringent monitoring standards to ensure a successful outcome for the patient. This case demonstrated that ClearSight has the potential to improve patient monitoring in hemodynamically stable patients who received kidney transplantation under general anesthesia. J. Med. Invest. 65:139-141, February, 2018.

A Comparison of Fosaprepitant and Ondansetron for Preventing Postoperative Nausea and Vomiting in Moderate to High Risk Patients: A Retrospective Database Analysis

Postoperative nausea and vomiting (PONV) occur in 30–50% of patients undergoing general anesthesia and in 70–80% of high PONV risk patients. In this study, we investigated the efficacy of fosaprepitant, a neurokinin-1 (NK1) receptor antagonist, compared to ondansetron, a selective 5-hydroxytryptamine type 3 (5-HT3) receptor antagonist, in moderate to high PONV risk patients from our previous randomized controlled trials. Patients (171 patients from 4 pooled studies) with the Apfel simplified score ≥ 2 and undergoing general anesthesia were randomly allocated to receive intravenous fosaprepitant 150 mg (NK1 group, n = 82) and intravenous ondansetron 4 mg (ONS group, n = 89) before induction of anesthesia. Incidence of vomiting was significantly lower in the NK1 group compared to the ONS group 0–2, 0–24, and 0–48 hours after surgery (2 versus 17%, 2 versus 28%, and 2 versus 29%, resp.). However, no significant differences in PONV, complete response, rescue antiemetic use, and nausea score were observed between groups 0–48 hours after surgery. In moderate to high PONV risk patients, fosaprepitant decreased the incidence of vomiting and was superior to ondansetron in preventing postoperative vomiting 0–48 hours after surgery.