Potentilla reptans L. postconditioning protects reperfusion injury via the RISK/SAFE pathways in an isolated rat heart.

BACKGROUND: Our previous study indicated that Potentilla reptans root has a preconditioning effect by its antioxidant and anti-apoptotic effects in an isolated rat heart ischemia/reperfusion (IR) model. In the present study, we investigated the post-conditioning cardio-protective effects of Potentilla reptans and its active substances. METHODS: The ethyl acetate fraction of P. reptans root (Et) was subjected to an IR model under 30 min of ischemia and 100 min of reperfusion. To investigate the postconditioning effect, Et was perfused for 15 min at the early phase of reperfusion. RISK/SAFE pathway inhibitors, 5HD and L-NAME, were applied individually 10 min before the ischemia, either alone or in combination with Et during the early reperfusion phase. The hemodynamic factors and ventricular arrhythmia were calculated during the reperfusion. Oxidative stress, apoptosis markers, GSK-3ß and SGK1 proteins were assessed at the end of experiments. RESULTS: Et postconditioning (Etpost) significantly reduced the infarct size, arrhythmia score, ventricular fibrillation incidence, and enhanced the hemodynamic parameters by decreasing the MDA level and increasing expression of Nrf2, SOD and CAT activities. Meanwhile, Etpost increased the BCl-2/BAX ratio and decreased Caspase-3 expression. The cardioprotective effect of Etpost was abrogated by L-NAME, Wortmannin (a PI3K/Akt inhibitor), and AG490 (a JAK/STAT3 inhibitor). Finally, Etpost reduced the expression of GSK-3ß and SGK1 proteins pertaining to the IR group. CONCLUSION: P. reptans reveals the post-conditioning effects via the Nrf2 pathway, NO release, and the RISK/SAFE pathway. Also, Etpost decreased apoptotic indexes by inhibiting GSK-3ß and SGK1 expressions. Hence, our data suggest that Etpost can be a suitable natural candidate to protect cardiomyocytes during reperfusion injury.

Antibiotic resistance in the pathogenic foodborne bacteria isolated from raw kebab and hamburger: phenotypic and genotypic study.

BACKGROUND: In recent years, interest in the consumption of ready-to-eat (RTE) food products has been increased in many countries. However, RTE products particularly those prepared by meat may be potential vehicles of antibiotic-resistance foodborne pathogens. Considering kebab and hamburger are the most popular RTE meat products in Iran, this study aimed to investigate the prevalence and antimicrobial resistance of common foodborne pathogens (Escherichia coli, Salmonella spp., Staphylococcus aureus, and Listeria monocytogenes) in raw kebab and hamburger samples collected from fast-food centers and restaurants. Therefore, total bacterial count (TBC), as well as the prevalence rates and antibiogram patterns of foodborne pathogens in the samples were investigated. Also, the presence of antibiotic-resistance genes (blaSHV, blaTEM, blaZ, and mecA) was studied in the isolates by PCR. RESULTS: The mean value of TBC in raw kebab and hamburger samples was 6.72 ± 0.68 log CFU/g and 6.64 ± 0.66 log CFU/g, respectively. E. coli had the highest prevalence rate among the investigated pathogenic bacteria in kebab (70%) and hamburger samples (48%). Salmonella spp., L. monocytogenes, and S. aureus were also recovered from 58, 50, and 36% of kebab samples, respectively. The contamination of hamburger samples was detected to S. aureus (22%), L. monocytogenes (22%), and Salmonella spp. (10%). In the antimicrobial susceptibility tests, all isolates exhibited high rates of antibiotic resistance, particularly against amoxicillin, penicillin, and cefalexin (79.66-100%). The blaTEM was the most common resistant gene in the isolates of E. coli (52.54%) and Salmonella spp. (44.11%). Fourteen isolates (23.72%) of E. coli and 10 isolates (29.41%) of Salmonella spp. were positive for blaSHV. Also, 16 isolates (55.17%) of S. aureus and 10 isolates (27.27%) of L. monocytogenes were positive for mecA gene. CONCLUSIONS: The findings of this study showed that raw kebab and hamburger are potential carriers of antibiotic-resistance pathogenic bacteria, which can be a serious threat to public health.

Preconditioning and anti-apoptotic effects of Metformin and Cyclosporine-A in an isolated bile duct-ligated rat heart.

Despite all previous studies relating to the mechanism of cirrhotic cardiomyopathy (CCM), the role of cirrhosis on Ischemic Preconditioning (IPC) has not yet been explored. The present study strives to assess the cardioprotective role of IPC in bile duct ligated (BDL) rats as well as the cardioprotective role of Cyclosporin-A (CsA) and Metformin (Met) in CCM. Cirrhosis was induced by bile duct ligation (BDL). Rats' hearts were isolated and attached to a Langendorff Apparatus. The pharmacological preconditioning with Met and CsA was done before the main ischemia. Myocardial infarct size, hemodynamic and electrophysiological parameters, biochemical markers, and apoptotic indices were determined at the end of the experiment. Infarct size, apoptotic indices, arrhythmia score, and incidence of VF decreased significantly in the IPC group in comparison with the I/R group. These significant decreases were abolished in the IPC (BDL) group. Met significantly decreased the infarct size and apoptotic indices compared with I/R (BDL) and normal groups, while CsA led to similar decreases except in the level of caspase-3 and -8. Met and CsA decreased and increased the arrhythmia score and incidence of VF in the BDL groups, respectively. Functional recovery indices decreased in the I/R (BDL) and IPC (BDL) groups. Met improved these parameters. Therefore, the current study depicted that the cardioprotective effect of Met and CsA on BDL rats is mediated through the balance between pAMPK and apoptosis in the mitochondria.

Targeting autophagy in cardiac ischemia/reperfusion injury: A novel therapeutic strategy.

Acute myocardial infarction (AMI) is one of the leading causes of morbidity worldwide. Myocardial reperfusion is known as an effective therapeutic choice against AMI. However, reperfusion of blood flow induces ischemia/reperfusion (I/R) injury through different complex processes including ion accumulation, disruption of mitochondrial membrane potential, the formation of reactive oxygen species, and so forth. One of the processes that gets activated in response to I/R injury is autophagy. Indeed, autophagy acts as a "double-edged sword" in the pathology of myocardial I/R injury and there is a controversy about autophagy being beneficial or detrimental. On the basis of the autophagy effect and regulation on myocardial I/R injury, many studies targeted it as a therapeutic strategy. In this review, we discuss the role of autophagy in I/R injury and its targeting as a therapeutic strategy.

Functional biological pacemaker generation by T-Box18 protein expression via stem cell and viral delivery approaches in a murine model of complete heart block.

Despite recent advances in the treatment of cardiac arrhythmia, the available options are still limited and associated with some complications. Induction of biological pacemakers via Tbx18 gene insertion in the heart tissue has been suggested as a promising therapeutic strategy for cardiac arrhythmia. Following a previous in vitro study reporting the production of Tbx18-expressing human induced pluripotent stem cell-derived cardiomyocytes (hiPS-CMs), we aimed to investigate the efficacy of these engineered cells to generate pacemaker rhythms in a murine model of complete heart block. We also attempted to generate a functional pacemaker by Tbx18 overexpression in native cardiac cells of rat heart. The hiPSC-derived pacemaker cells were produced by lentiviral delivery of Tbx18 gene to stem cells during a small molecule-based differentiation process. In the present study, 16 male albino Wistar rats were randomly assigned to Tbx18-lentivirus (n = 4) and Tbx18-pacemaker cells (n = 4) administered via injection into the left ventricular anterolateral wall. The control rats received GFP-lentiviruses (n = 4) and GFP-pacemaker cells (n = 4). Fourteen days after the injection, the rats were sacrificed and analyzed by electrocardiography (ECG) recording using a Langendorff-perfused heart model following complete heart block induced by hypokalemia and crashing. Immunofluorescence staining was used to investigate the expression of Tbx18, HCN4 and connexin 43 (Cx43) proteins in Tbx18-delivered cells of heart tissues. The heart rate was significantly reduced after complete heart block in all of the experimental rats (P < 0.05). Heart beating in the Tbx18-transduced hearts was slower compared with rats receiving Tbx18-pacemaker cells (P = 0.04). The duration of ventricular fibrillation (VF) was higher in the lentiviral Tbx18 group compared with the GFP-injected controls (P = 0.02) and the Tbx18-pacemaker cell group (P = 0.02). The ECG recording data showed spontaneous pacemaker rhythms in both intervention groups with signal propagation in Tbx18-transduced ventricles. Immunostaining results confirmed the overexpression of HCN4 and downregulation of Cx43 as a result of the expression of the Tbx18 gene and spontaneously contracting myocyte formation. We confirmed the formation of a functional pacemaker after introduction of Tbx18 via cell and gene therapy strategies. Although the pacemaker activity was better in gene-received hearts since there were longer VF duration and signal propagation from the injection site, more data should be gathered from the long-term activity of such pacemakers in different hosts.

The SAFE pathway is involved in the postconditioning mechanism of oxytocin in isolated rat heart.

Oxytocin (OT) has a postconditioning effect against the ischemia-reperfusion (I/R) injury. However, its precise cardioprotection mechanism at the early reperfusion phase remains under debate. Our previous study revealed that OT postconditioning (OTpost) is cardioprotective by activating the Reperfusion Injury Salvage Kinase (RISK) pathway. Therefore, the present study is aimed to determine the biological effects of OTpost via the OT receptor and the activation of the JAK/STAT3 signaling pathway, mitochondrial adenosine triphosphate-dependent potassium channel (mitoKATP), nitric oxide (NO) release, and its anti-apoptotic effects against I/R injury in an isolated rat heart model. Sixty-three rats were randomly allocated to one of nine groups. OT was perfused 40 min prior to the regional ischemia or 15 min at the early reperfusion phase. AG490 (a JAK/STAT3 inhibitor), 5HD (a mitoKATP blocker), atosiban (an OT receptor antagonist), L-NAME (a nonspecific nitric oxide synthase inhibitor) were applied either alone or in combination with OT during the pre-ischemia phase and/or in the early reperfusion phase. Myocardial infarct size, hemodynamic factor, ventricular arrhythmia, coronary flow, cardiac biochemical marker, and the apoptosis index were determined at the end of reperfusion. Oxytocin postconditioning reduced infarct size, lactate dehydrogenase activity, arrhythmia score, ventricular fibrillation, and apoptosis. Moreover, AG490, 5HD, atosiban, and L-NAME abrogated the cardioprotective effects of OT. Our results demonstrated that the cardioprotective effects of OT are mediated by NO release, and the activation of mitoKATP and the SAFE pathway through the JAK/STAT3 signaling cascade that finally lead to decrease in the apoptosis index during the early reperfusion phase.

Cardioprotective and anti-apoptotic effects of Potentilla reptans L. root via Nrf2 pathway in an isolated rat heart ischemia/reperfusion model.

BACKGROUND: Previous studies have shown that proanthocyanidins have cardioprotective effects which are mediated via the release of nitric oxide (NO) ultimately resulting in increasing the antioxidant activity. We have investigated to show whether 1) the total extract and ethyl acetate fraction (Et) of Potentilla reptans root have an ischemic preconditioning (IPC) effect, 2) P. reptans has antioxidant and cardioprotective effects mediated by nuclear factor erythroid 2-related factor 2 (Nrf2) pathway and scavenging of reactive oxygen species (ROS), 3) NO, caspase-3 and Bcl-2/Bax are involved in the IPC effect of P. reptans. METHODS: Male Wistar rats were divided into 10 groups. The isolated hearts were subjected to 30 min of ischemia and 100 min of reperfusion. The P. reptans was applied before the main ischemia. The infarct size was estimated by triphenyl-tetrazolium chloride staining. The hemodynamic parameters and ventricular arrhythmias were calculated during the reperfusion. Antioxidant markers and immunohistochemistry assays were determined at the end of the protocol. RESULTS: The Et significantly decreased the infarct size, arrhythmia scores, ventricular fibrillation incidence, and enhanced the hemodynamic parameters in a concentration-dependent manner against the ischemia/reperfusion group. SOD and CAT activity were increased and MDA level was decreased in response to the Et. Meanwhile, Et attenuated the suppression of Nrf2 expression and reduced the apoptotic indexes. The cardioprotective effect of P. reptans was abrogated by L-NAME. CONCLUSIONS: P. reptans demonstrated that the cardioprotective preconditioning effects via NO release, Nrf2 pathway, and antioxidant activity lead to a decrease in the apoptotic index.