[Thrombotic microangiopathy with gastrointestinal hemorrhage during carfilzomib therapy for multiple myeloma].

A 70-year-old woman was admitted to the hospital with loss of appetite and melena. She was diagnosed with multiple myeloma 7 years ago and had been on carfilzomib, lenalidomide, and dexamethasone (KRd) therapy for a month because her disease had a relapsed/refractory. On admission, her laboratory tests revealed hemolytic anemia with schizocytes, thrombocytopenia, and acute renal dysfunction. TMA (thrombotic microangiography) caused by carfilzomib was suspected. The possibility of thrombotic thrombocytopenia was considered, and steroid pulse therapy was initiated. Her condition improved significantly after she stopped taking carfilzomib, plasma exchange, hemodiafiltration, steroid pulse therapy, and abstaining from food. The previously reported cases of carfilzomib-induced TMA included fever, gastrointestinal symptoms (nausea/vomiting, diarrhea), and acute renal disorders (lower extremity edema, decreasing urine output). As far as we know, this is the first case of carfilzomib-induced TMA with bleeding as the first symptom.

Discovery of a Tricyclic ß-Lactam as a Potent Antimicrobial Agent against Carbapenem-Resistant Enterobacterales, Including Strains with Reduced Membrane Permeability and Four-Amino Acid Insertion into Penicillin-Binding Protein 3: Structure-Activity-Relationships and In Vitro and In Vivo Activities.

The current worldwide emergence of carbapenem-resistant enterobacterales (CREs) constitutes an important growing clinical and public health threat. Acquired carbapenemases are the most important determinants of resistance to carbapenems. In the development of the previously reported tricyclic ß-lactam skeleton which exhibits potent antibacterial activities against several problematic ß-lactamase-producing CREs without a ß-lactamase inhibitor, we found that these activities were reduced against clinical isolates with resistance mechanisms other than ß-lactamase production. These mechanisms were the reduction of outer membrane permeability with the production of ß-lactamases and the insertion of four amino acids into penicillin-binding protein 3. Here, we report the discovery of a potent compound that overcomes these resistance mechanisms by the conversion of the alkoxyimino moiety of the aminothiazole side chain in which a hydrophilic functional group is introduced and the carboxylic acid of the alkoxyimino moiety is converted to reduce the negative charge of the whole molecule from 2 to 1. This potent tricyclic ß-lactam is a promising drug candidate for infectious diseases caused by CREs due to its potent therapeutic efficacy in the neutropenic mouse lung infection model and low frequency of producing spontaneously resistant mutants.

A novel tricyclic ß-lactam exhibiting potent antibacterial activities against carbapenem-resistant Enterobacterales: Synthesis and structure-activity-relationships.

A series of tricyclic ß-lactams were synthesized and evaluated for in vitro antibacterial activities against carbapenem-resistant Enterobacterales (CREs). Starting from a reported tricyclic ß-lactam that combined the cephalosporin skeleton having a γ-lactone ring with a carboxylic acid group, which was reported as a unique partial structure of Lactivicin, we identified the compound which shows potent antibacterial activities against all tested CREs by introducing sulfoxide. In addition, the sulfoxide-introduced tricyclic ß-lactam also shows a strong therapeutic efficacy in the neutropenic mouse lung infection model. These results indicate that the tricyclic ß-lactam skeleton will show sufficient therapeutic performance in clinical use and therefore can serve as a scaffold in the search for new antibacterial agents against CREs.

In Vitro Activity and In Vivo Efficacy of Cefiderocol against Stenotrophomonas maltophilia.

Cefiderocol is a novel siderophore cephalosporin antibiotic with broad coverage against difficult-to-treat Gram-negative bacteria, including those resistant to carbapenems. Its activity against Stenotrophomonas maltophilia was investigated in vitro against clinical isolates and in lung infection models using strains either resistant (SR202006) or susceptible (SR201934, SR200614) to trimethoprim-sulfamethoxazole. Cefiderocol demonstrated potent in vitro activity against all 217 S. maltophilia clinical isolates tested (MIC50, 0.063 µg/ml; MIC90, 0.25 µg/ml). Cefiderocol also demonstrated low MICs against the trimethoprim-sulfamethoxazole-resistant S. maltophilia strains (i.e., SR202006; MIC, 0.125 µg/ml). In a neutropenic mouse lung infection model, cefiderocol (30 mg/kg body weight and 100 mg/kg) demonstrated a significant, dose-dependent reduction in the lung viable bacteria cell count compared with untreated controls in S. maltophilia infection and was the only antibiotic tested to show a similar significant effect in a trimethoprim-sulfamethoxazole-resistant S. maltophilia infection. In immunocompetent rat lung infection models of S. maltophilia, humanized dosing of cefiderocol (2 g every 8 h) and meropenem (1 g every 8 h) revealed pharmacokinetic profiles similar to those in human subjects, and the humanized cefiderocol dosing significantly reduced the lung viable bacteria cell count compared with baseline controls, which received no intervention. Together, the results from these studies suggest that cefiderocol could provide an effective alternative treatment option for S. maltophilia infections in the lower respiratory tract, particularly strains resistant to empirical antibiotics, such as trimethoprim-sulfamethoxazole or minocycline.

Allergen-Related Coronary Vasospasm "Kounis Syndrome" Requiring Administration of Epinephrine and a Coronary Vasodilator.

Kounis syndrome is an anaphylactic reaction leading to acute coronary syndrome. The acute treatment of anaphylaxis is epinephrine; however, epinephrine may cause coronary vasoconstriction, reduce coronary blood flow, increase myocardial oxygen demand, and worsen myocardial ischemia. On the other hand, coronary vasodilation, a treatment for acute coronary syndrome, can aggravate hypotension in patients with anaphylaxis. Herein, the authors report a case of type II Kounis syndrome, with vasospasm in a patient with coronary disease, requiring the administration of epinephrine and a coronary vasodilator for resuscitation. The authors administered intravenous epinephrine continuously from lower dosages and performed delicate titration. The coronary vasodilator nicorandil, which has little effect on hemodynamics, also was administered. These treatments improved hemodynamics without complications. Circulatory management that considers both anaphylaxis and coronary lesions is crucial to improve prognosis in this syndrome.

Activities of Cefiderocol with Simulated Human Plasma Concentrations against Carbapenem-Resistant Gram-Negative Bacilli in an In Vitro Chemostat Model.

Activities of cefiderocol under simulated human plasma concentrations at the recommended dosing regimen of 2 g every 8 h with a 3-h infusion were evaluated using an in vitro chemostat model. Against a total of 6 meropenem-resistant Gram-negative strains with cefiderocol MICs of 0.5 to 4 µg/ml, including metallo-ß-lactamase producers and carbapenem-resistant Acinetobacter baumannii, cefiderocol treatment showed a bactericidal effect within 8 h and sustained efficacy with no marked bacterial regrowth over 24 h.

Association between Enterocyte Injury and Mortality in Patients on Hemodialysis Who Underwent Cardiac Surgery: An Exploratory Study.

BACKGROUND: Intestinal ischemia and enterocyte injury are significant causes of death after cardiac surgery. Hemodialysis is a well-known risk factor for intestinal ischemia. However, the relationship between enterocyte injury and mortality is unclear. This exploratory study assessed the association between intestinal fatty acid-binding protein (I-FABP), a specific marker of enterocyte injury, at intensive care unit (ICU) admission and in-hospital mortality in patients on hemodialysis who underwent cardiac surgery with cardiopulmonary bypass. MATERIALS AND METHODS: Forty-seven consecutive patients on long-term hemodialysis who underwent elective cardiac surgery (median age, 70 y; men, 27 [57%]) were prospectively enrolled. The association between serum I-FABP levels at ICU admission and in-hospital mortality was compared with the associations between serum I-FABP levels and prognostic severity scores, vasoactive-inotropic scores, and lactate levels. RESULTS: Only I-FABP levels at ICU admission were significantly related to in-hospital mortality (odds ratio, 5.54; 95% confidence interval [CI], 1.08-28.43) in the simple logistic regression analysis. Univariate and multiple linear regression analyses indicated prolonged cardiopulmonary bypass (ρ, 0.49; 95% CI, 0.15-0.83), higher mean norepinephrine dose (ρ, 0.07; 95% CI, 0.02-0.12), lower mean dopamine dose (ρ, -0.51; 95% CI, -0.94 to -0.08), and intra-aortic balloon pump use (ρ, 3.63; 95% CI, 1.68-5.59) were significant risk factors for high I-FABP levels. CONCLUSIONS: Enterocyte injury at ICU admission was associated with in-hospital mortality after cardiac surgery for patients on hemodialysis. Intraoperative hidden hypoperfusion of the intestine may impact prognoses. Enterocyte injury prevention, early diagnosis, and intervention for intestinal ischemia might be required to improve outcomes.

Escherichia coli strains possessing a four amino acid YRIN insertion in PBP3 identified as part of the SIDERO-WT-2014 surveillance study.

BACKGROUND: In addition to carbapenemases, dissemination of recently reported Escherichia coli lineages possessing a four amino acid insertion in PBP3 (encoded by ftsI) that confers reduced susceptibility to PBP3-targeted ß-lactams, such as ceftazidime, can pose a threat of antimicrobial resistance. OBJECTIVES: To evaluate genotypic and phenotypic characteristics of E. coli possessing the mutated PBP3 collected during SIDERO-WT-2014 surveillance. METHODS: A subset of 65 E. coli clinical isolates with MICs ≥2 mg/L for ceftazidime/avibactam, ceftolozane/tazobactam or cefiderocol, among a total of 1529 isolates from the multinational surveillance study, were subjected to gene analysis and antimicrobial susceptibility testing. Isogenic PBP3 mutants were constructed to confirm experimentally an impact on antimicrobial susceptibility. RESULTS: Eleven strains possessing a YRIN-inserted PBP3 were identified, consisting of nine strains collected from the same hospital in Turkey (ST1284) and one each from the USA and Italy (ST361). Strains associated with each ST lineage possessed similar genetic backgrounds including ß-lactamase genotypes; all nine strains from Turkey carried CMY-42, OXA-1 and the OXA-181 carbapenemase (five strains additionally carried CTX-M-15 ESBL), whereas the two other strains carried CMY-42 and TEM-1, indicating dissemination driven by selective pressure. The presence of the YRIN insertion contributed to reduced susceptibility to aztreonam, ceftazidime, cefepime and ceftolozane/tazobactam, although the strains remained susceptible to ceftazidime/avibactam despite relatively high MICs. CONCLUSIONS: E. coli strains of both ST1284 and ST361 lineages, possessing YRIN-inserted PBP3, are disseminating in several regions. The YRIN insertion in PBP3 occurred with multiple ß-lactamases, which indicates frequent cross-resistance to other ß-lactams.

Association between endotoxemia and enterocyte injury and clinical course in patients with gram-positive septic shock: A posthoc analysis of a prospective observational study.

Endotoxemia often occurs in patients with gram-positive infections. The possible mechanism is thought to be bacterial translocation after enterocyte hypoperfusion injury. However, the association between endotoxemia and enterocyte injury among patients with gram-positive septic shock has never been assessed. The aim of this study was to evaluate the association between endotoxemia and enterocyte injury in gram-positive septic shock patients and to evaluate the association among endotoxemia, subsequent clinical course, and other related factors.This was a posthoc analysis of a prospective observational study that evaluated the capability of intestinal fatty acid-binding protein (I-FABP), an indicator of enterocyte injury, to predict mortality. Among 57 patients in septic shock, those whose causative microorganisms were gram positive were included. The correlation between endotoxin activity (EA), which indicates endotoxemia, and I-FABP levels upon admission to the intensive care unit (ICU), the clinical course, and other related factors were evaluated.A total of 21 patients were examined. One-third of the patients presented with high EA levels at the time of ICU admission. However, there was no significant correlation between EA and I-FABP levels (Spearman ρ = 0.002, P = .993). Additionally, high EA levels were not associated with abdominal complications after ICU admission or mortality. Similarly, high EA levels were not associated with severity scores, inotropic scores, or lactate levels upon ICU admission, which were previously reported to be factors related to high EA levels.In this posthoc analysis, no correlation was observed between endotoxemia and enterocyte injury among patients in gram-positive septic shock. Additionally, high EA levels were not associated with the clinical course and reported factors related to endotoxemia. Although our results need to be validated in a large prospective cohort study, hypoperfusion enterocyte injury might not be a cause of endotoxemia in these patients. Thus, if there is no correlation between EA and I-FABP levels, other mechanisms that induce high EA levels among patients with gram-positive septic shock should be elucidated.

In Vivo Pharmacodynamic Study of Cefiderocol, a Novel Parenteral Siderophore Cephalosporin, in Murine Thigh and Lung Infection Models.

The pharmacokinetic (PK) and pharmacodynamic (PD) parameters which correlated with the in vivo efficacy of cefiderocol were evaluated using neutropenic murine thigh and lung infection models in which the infections were caused by a variety of Gram-negative bacilli. The dose fractionation study using the thigh infection model in which the infection was caused by Pseudomonas aeruginosa showed that the cumulative percentage of a 24-h period that the free drug concentration in plasma exceeds the MIC (%fT>MIC) rather than the free peak level divided by the MIC (fCmax/MIC) and the area under the free concentration-time curve over 24 h divided by the MIC (fAUC/MIC) was the PK/PD parameter that best correlated with efficacy. The study with multiple carbapenem-resistant strains revealed that the %fT>MIC determined in iron-depleted cation-adjusted Mueller-Hinton broth (ID-CAMHB) better reflected the in vivo efficacy of cefiderocol than the %fT>MIC determined in cation-adjusted Mueller-Hinton broth (CAMHB). The mean %fT>MIC of cefiderocol required for a 1-log10 reduction against 10 strains of Enterobacteriaceae and 3 strains of Pseudomonas aeruginosa in the thigh infection models were 73.3% and 77.2%, respectively. The mean %fT>MIC for Enterobacteriaceae, P. aeruginosa, Acinetobacter baumannii, and Stenotrophomonas maltophilia in the lung infection model were 64.4%, 70.3%, 88.1%, and 53.9%, respectively. These results indicate that cefiderocol has potent efficacy against Gram-negative bacilli, including carbapenem-resistant strains, irrespective of the bacterial species, in neutropenic thigh and lung infection models and that the in vivo efficacy correlated with the in vitro MIC under iron-deficient conditions.

Association Between Macroscopic Tongue Ischemia and Enterocyte Injury and Poor Outcome in Patients With Septic Shock: A Preliminary Observational Study.

A correlation between sublingual and intestinal mucosa microcirculation, and ischemic necrosis of the tongue as a sign of poor prognosis has been reported. However, an association between tongue ischemia and intestinal health and subsequent outcome has never been studied. This preliminary prospective observational study evaluated the association between macroscopic tongue ischemia and enterocyte injury and poor outcome in patients with septic shock. In this study, 57 adults with septic shock on mechanical ventilators were enrolled. Macroscopic tongue ischemia upon intensive care unit (ICU) admission was assessed by two independent intensivists. We used intestinal fatty-acid binding protein (I-FABP) as a biomarker of enterocyte injury and evaluated the association with tongue ischemia. Demographic variables, risk factor data, and 28-day mortality information were also collected. Compared with patients with normal tongues (n = 45), those with ischemic tongues (n = 12) had a significantly higher Acute Physiology and Chronic Health Evaluation II score (29.0 [25.0-34.0] vs. 36.5 [30.5-44.5], P = 0.017), lactate level (2.8 [2.0-5.0] vs. 9.3 [4.5-10.6], P = 0.002), and I-FABP level (1.9 [0.8-4.0] vs. 54.4 [19.5-159.3], P < 0.001) and the all-cause 28-day mortality was significantly higher (7% vs. 83%, P < 0.001). In conclusion, macroscopic tongue ischemia at ICU admission was associated with enterocyte injury and poor outcome in patients with septic shock. Although there is a disadvantage in that assessment of the tongue was subjective, tongue ischemia could be used to gauge the severity of intestinal injury and to estimate poor outcome in the clinical setting.

In Vitro Antibacterial Properties of Cefiderocol, a Novel Siderophore Cephalosporin, against Gram-Negative Bacteria.

Cefiderocol (CFDC; S-649266), a novel parenteral siderophore cephalosporin conjugated with a catechol moiety, has a characteristic antibacterial spectrum with a potent activity against a broad range of aerobic Gram-negative bacterial species, including carbapenem-resistant strains of Enterobacteriaceae and nonfermenting bacteria such as Pseudomonas aeruginosa and Acinetobacter baumannii Cefiderocol has affinity mainly for penicillin-binding protein 3 (PBP3) of Enterobacteriaceae and nonfermenting bacteria similar to that of ceftazidime. A deficiency of the iron transporter PiuA in P. aeruginosa or both CirA and Fiu in Escherichia coli caused 16-fold increases in cefiderocol MICs, suggesting that these iron transporters contribute to the permeation of cefiderocol across the outer membrane. The deficiency of OmpK35/36 in Klebsiella pneumoniae and the overproduction of efflux pump MexA-MexB-OprM in P. aeruginosa showed no significant impact on the activity of cefiderocol.

Intestinal fatty acid-binding protein level as a predictor of 28-day mortality and bowel ischemia in patients with septic shock: A preliminary study.

PURPOSE: We sought to evaluate the levels of intestinal fatty acid-binding protein (I-FABP), a biomarker of enterocyte injury, as a predictor of 28-day mortality and bowel ischemia in septic shock patients. MATERIAL AND METHODS: In this preliminary prospective observational study, 57 adult septic shock patients under mechanical ventilation were enrolled. Serum I-FABP levels and prognostic biomarkers were recorded upon intensive care unit (ICU) admission. RESULTS: The overall 28-day mortality rate of participants was 23% (13/57). Non-survivors displayed significantly higher lactate (p=0.009), I-FABP (p=0.012), and N-terminal pro-B-type natriuretic peptide (p=0.039) levels compared to survivors. Only I-FABP was associated with 28-day mortality (odds ratio, 1.036; 95% confidence interval, 1.003-1.069; p=0.031) in a multiple logistic regression analysis adjusted for the Acute Physiology and Chronic Health Evaluation II score. When divided into low and high I-FABP groups based on the optimum cut-off value of 19.0ng/mL for predicting 28-day mortality, high-I-FABP patients had a significantly higher incidence of non-occlusive mesenteric ischemia (NOMI) (2% [1/43] vs 29% [4/14]; p=0.011). CONCLUSIONS: I-FABP level at ICU admission can serve as a predictor of 28-day mortality in septic shock patients and is associated with the incidence of NOMI.

Efficacy of Cefiderocol against Carbapenem-Resistant Gram-Negative Bacilli in Immunocompetent-Rat Respiratory Tract Infection Models Recreating Human Plasma Pharmacokinetics.

Cefiderocol (S-649266), a novel siderophore cephalosporin, shows potent activity against carbapenem-resistant Gram-negative bacilli. In this study, we evaluated the efficacy of cefiderocol against carbapenem-resistant Gram-negative bacilli (Pseudomonas aeruginosa, Acinetobacter baumannii, and Klebsiella pneumoniae) in immunocompetent-rat respiratory tract infection models recreating plasma pharmacokinetics (PK) profiles in healthy human subjects. A total of 6 clinical isolates (1 cephalosporin-susceptible P. aeruginosa isolate, 1 multidrug-resistant P. aeruginosa isolate, 2 multidrug-resistant A. baumannii isolates, and 2 carbapenem-resistant K. pneumoniae isolates) were evaluated. Four-day treatment with a human exposure of 1 g ceftazidime every 8 h as a 0.5-h infusion showed potent efficacy only against a ceftazidime-susceptible isolate, not against five ceftazidime-resistant isolates harboring carbapenemase. With cefiderocol, a human exposure of 2 g every 8 h as a 3-h infusion for 4 days produced a >3 log10 reduction in the number of viable cells of these carbapenem-resistant isolates in the lungs. When the infusion time was 1 h, bactericidal activity was also observed against all isolates tested, although for 2 of 5 carbapenem-resistant isolates, a 3 log10 reduction was not achieved. The difference in efficacy achieved by changing the infusion period from 1 h to 3 h was considered to be due to the higher percentage of the dosing interval during which free-drug concentrations were above the MIC (%fTMIC), as observed for ß-lactam antibiotics. These results suggest the potential utility of cefiderocol for the treatment of lung infections caused by carbapenem-resistant P. aeruginosa, A. baumannii, and K. pneumoniae strains.

Endoscopic gastric atrophy is strongly associated with gastric cancer development after Helicobacter pylori eradication.

BACKGROUND: Risk factors for gastric cancer during continuous infection with Helicobacter pylori have been well documented; however, little has been reported on the risk factors for primary gastric cancer after H. pylori eradication. We conducted a retrospective, endoscopy-based, long-term, large-cohort study to clarify the risk factors for gastric cancer following H. pylori eradication. METHODS: Patients who achieved successful H. pylori eradication and periodically underwent esophagogastroduodenoscopy surveillance thereafter at Toyoshima Endoscopy Clinic were enrolled. The primary endpoint was the development of gastric cancer. Statistical analysis was performed using the Kaplan-Meier method and Cox's proportional hazards models. RESULTS: Gastric cancer developed in 15 of 1232 patients. The cumulative incidence rates were 1.0 % at 2 years, 2.6 % at 5 years, and 6.8 % at 10 years. Histology showed that all gastric cancers (17 lesions) in the 15 patients were of the intestinal type, within the mucosal layer, and <20 mm in diameter. Based on univariate analysis, older age and higher endoscopic grade of gastric atrophy were significantly associated with gastric cancer development after eradication of H. pylori, and gastric ulcers were marginally associated. Multivariate analysis identified higher grade of gastric atrophy (hazard ratio 1.77; 95 % confidence interval 1.12-2.78; P = 0.01) as the only independently associated parameter. CONCLUSIONS: Endoscopic gastric atrophy is a major risk factor for gastric cancer development after H. pylori eradication. Further long-term studies are required to determine whether H. pylori eradication leads to regression of H. pylori-related gastritis and reduces the risk of gastric cancer.

Siderophore Cephalosporin Cefiderocol Utilizes Ferric Iron Transporter Systems for Antibacterial Activity against Pseudomonas aeruginosa.

Cefiderocol (S-649266) is a novel parenteral siderophore cephalosporin conjugated with a catechol moiety at the third-position side chain. The in vitro activity of cefiderocol against Pseudomonas aeruginosa was enhanced under iron-depleted conditions, whereas that of ceftazidime was not affected. The monitoring of [thiazole-14C]cefiderocol revealed the increased intracellular accumulation of cefiderocol in P. aeruginosa cells incubated under iron-depleted conditions compared with those incubated under iron-sufficient conditions. Cefiderocol was shown to have potent chelating activity with ferric iron, and extracellular iron was efficiently transported into P. aeruginosa cells in the presence of cefiderocol as well as siderophores, while enhanced transport of extracellular ferric iron was not observed when one of the hydroxyl groups of the catechol moiety of cefiderocol was replaced with a methoxy group. We conclude that cefiderocol forms a chelating complex with iron, which is actively transported into P. aeruginosa cells via iron transporters, resulting in potent antibacterial activity of cefiderocol against P. aeruginosa.

Protective effect of lactoferrin on acute acid reflux-induced esophageal mucosal damage.

BACKGROUND/AIMS: The natural immunomodulator lactoferrin is known to possess anti-inflammatory effects. However, there have been no studies examining the mode of action of lactoferrin in protecting the esophageal mucosa against damage. We investigated the effect of lactoferrin on gastric acid secretion and in protecting against acute acid reflux-induced esophagitis in rats. METHODOLOGY: Male Wistar rats aged 8 weeks, weighing 210-240 g, were used for all the experiments. A gastric perfusion system was installed using the method of Ghosh et al. Lactoferrin was administered once via the caudate vein, starting 24 hours before an acute acid reflux (treatment mode), or saline (control). Statistical comparison of the parameters between the two test conditions was performed. RESULTS: No significant differences in basal or stimulated gastric acid secretion, or in the serum gastrin level were observed between the two test conditions. Esophageal damage was attenuated by lactoferrin in a dose-dependent manner, as reflected by the improvement in the esophageal tissue weight and macroscopic scores. Significant reductions in the histological scores, myeloperoxidase activity and the levels of proinflammatory cytokines, tumor necrosis factor-α and interleukin-1ß were also observed following lactoferrin administration. CONCLUSIONS: We concluded that lactoferrin exerts a protective effect against acute acid reflux-induced esophageal damage in rats.

High-dose fasudil preserves postconditioning against myocardial infarction under hyperglycemia in rats: role of mitochondrial KATP channels.

BACKGROUND: The current study was carried out to determine whether fasudil hydrochloride (fasudil), a Rho-kinase inhibitor, has myocardial postconditioning (PostC) activity under hyperglycemia as well as normoglycemia, and if so, whether the effects could be mediated by mitochondrial ATP-sensitive potassium (m-KATP) channels. METHODS: Male Sprague-Dawley rats were anesthetized with sodium pentobarbital. After opening the chest, all rats underwent 30-min coronary artery occlusion followed by 2-h reperfusion. The rats received low-dose (0.15 mg/kg) or high-dose (0.5 mg/kg) fasudil or diazoxide, an m-KATP channel opener, at 10 mg/kg, just before reperfusion under normoglycemic or hyperglycemic conditions. In another group, rats received 5-hydroxydecanoic acid (5HD), an m-KATP channel blocker, at 10 mg/kg, before high-dose fasudil. Myocardial infarct size was expressed as a percentage of area at risk (AAR). RESULTS: Under normoglycemia, low-dose and high-dose fasudil and diazoxide reduced myocardial infarct size (23 ± 8%, 21 ± 9% and 21 ± 10% of AAR, respectively) compared with that in the control (42 ± 7%). Under hyperglycemia, low-dose fasudil (40 ± 11%) and diazoxide (44 ± 14%) could not exert this beneficial effect, but high-dose fasudil reduced myocardial infarct size in the same manner as under normoglycemia (21 ± 13%). 5HD prevented fasudil-induced reduction of myocardial infarct size (42 ± 13%). CONCLUSION: Fasudil induces PostC against myocardial infarction via activation of m-KATP channels in the rat. Although hyperglycemia attenuates the PostC, high-dose fasudil can restore cardioprotection.

Hyperglycemia raises the threshold of levosimendan- but not milrinone-induced postconditioning in rat hearts.

BACKGROUND: The authors examined whether milrinone and levosimendan could exert cardiac postconditioning effects in rats under normoglycemia and hyperglycemia, and whether the effects could be mediated by mitochondrial permeability transition pore (mPTP). METHODS: Wistar rats underwent 30-min coronary artery occlusion followed by 2-h reperfusion. The rats received milrinone or levosimendan just before reperfusion under normoglycemic or hyperglycemic conditions with or without atractyloside, an mPTP opener. RESULTS: Under normoglycemia, both 30 µg/kg milrinone (29 ± 12%) and 10 µg/kg levosimendan (33 ± 13%) reduced infarct size compared with that in the control (58 ± 7%). Under hyperglycemia, milrinone (34 ± 13%) reduced infarct size at the same dose as under normoglycemia. In contrast, neither 10 nor 30 µg/kg levosimendan protected hyperglycemic hearts, and only 100 µg/kg levosimendan (32 ± 9%) reduced infarct size compared with that in the hyperglycemic control (58 ± 13%). All of these cardioprotective effects under normoglycemia and hyperglycemia are abolished by atractyloside. CONCLUSION: Milrinone and levosimendan exert postconditioning effects via inhibition of mPTP opening. Hyperglycemia raises the threshold of levosimendan-induced postconditioning, while milrinone-induced postconditioning is not influenced by hyperglycemia.

Roles of cyclooxygenase 2 in sevoflurane- and olprinone-induced early phase of preconditioning and postconditioning against myocardial infarction in rat hearts.

PURPOSE: It is known that selective cyclooxygenase 2(COX-2) inhibitors increase mortality in patients with previous myocardial infarction, and it has been suggested that COX-2 plays an important role in cardioprotection against ischemia. The current study was carried out to determine whether COX-2 is involved in the mechanisms of sevoflurane- and olprinone-induced early-phase preconditioning (E-PreC) and postconditioning (PostC) in rat hearts. METHODS: Male Sprague-Dawley rats were anesthetized with sodium pentobarbital. After opening the chest, all rats underwent 30-minute occlusion of left anterior descending coronary artery followed by 2-hour reperfusion, and the infarct size was measured after the reperfusion. The rats were randomly assigned to groups with pre- and postischemic exposure to sevoflurane and administration of olprinone with or without a selective COX-2 inhibitor, NS-398. RESULTS: The infarct size in the control group was 42% ± 6% of the area at risk. Infarct size was significantly reduced by pre- and postischemic administration of sevoflurane (16% ± 7% and 17% ± 6%, respectively), as well as by olprinone (14% ± 4% and 15% ± 10%, respectively). NS-398 prevented the protective effects of both pre- and postischemic exposure to sevoflurane (35% ± 8% and 42% ± 10%, respectively), whereas the protective effect of both pre- and postischemic administration of olprinone was not influenced by NS-398 (12% ± 5% and 19% ± 7%, respectively). CONCLUSIONS: Cyclooxygenase 2 could be a critical mediator of sevoflurane-induced but not olprinone-induced E-PreC or PostC in rat hearts.