Effects of salt intake reduction by urinary sodium to potassium ratio self-monitoring method

Effective and feasible educational methods are needed to control salt intake. We performed a single-center, non-randomized controlled study to investigate the effectiveness and feasibility of self-monitoring using a urinary sodium/potassium (Na/K) ratio-measuring device in patients with difficulty in reducing salt intake. This study included 160 patients with hypertension, chronic kidney disease, or heart disease who were followed up in the outpatient clinic of the Dokkyo Medical University Nikko Medical Center. Urinary Na/K ratio measuring Na/K ratio meter were loaned for 2-6 weeks to the treatment (T) group (n = 80) and not to the patients in the control (C) group (n = 80). In the T group, patients were instructed to measure the urinary Na/K ratio at least three times a day and maintain a Na/K ratio below 2.0. Salt reduction education and home blood pressure measurement guidance continued in both groups. The mean device loan period in the T group was 25.1 days, the mean number of measurements was 3.0 times/day, and the proportion of patients achieving three measurements per day was 48.8% (39/80). Self-monitoring using the urinary Na/K ratio meter successfully reduced salt intake by -1.9 g/day at the second visit (p < 0.001) in the T group. In contrast, no change was observed over time in the C group. Self-monitoring using the urinary Na/K ratio meter successfully reduced salt intake in patients with difficulty reducing salt intake.

Utility of growth differentiation factor-15 as a predictor of cardiovascular surgery outcomes: Current research and future directions

In a world increasingly confronted by cardiovascular diseases (CVDs) and an aging population, accurate risk assessment prior to cardiac surgery is critical. Although effective, traditional risk calculators such as the Japan SCORE, Society of Thoracic Surgeons score, and EuroSCORE II may not completely capture contemporary risks, particularly due to emerging factors such as frailty and sarcopenia. These calculators often focus on regional and ethnic specificity and rely heavily on evaluations based on age and underlying diseases. Growth differentiation factor-15 (GDF-15) is a stress-responsive cytokine that has been identified as a potential biomarker for sarcopenia and a tool for future cardiac risk assessment. Preoperative plasma GDF-15 levels have been associated with preoperative, intraoperative, and postoperative factors and short- and long-term mortality rates in patients undergoing cardiac surgery. Increased plasma GDF-15 levels have prognostic significance, having been correlated with the use of cardiopulmonary bypass during surgery, amount of bleeding, postoperative acute kidney injury, and intensive care unit stay duration. Notably, the inclusion of preoperative levels of GDF-15 in risk stratification models enhances their predictive value, especially when compared with those of the N-terminal prohormone of brain natriuretic peptide, which does not lead to reclassification. Thus, this review examines traditional risk assessments for cardiac surgery and the role of the novel biomarker GDF-15. This study acknowledges that the relationship between patient outcomes and elevated GDF-15 levels is not limited to CVDs or cardiac surgery but can be associated with variable diseases, including diabetes and cancer. Moreover, the normal range of GDF-15 is not well defined. Given its promise for improving patient care and outcomes in cardiovascular surgery, future research should explore the potential of GDF-15 as a biomarker for postoperative outcomes and target therapeutic intervention.

Skeletal Muscle Quality Assessment in Patients With Cardiac Disease Associated With Type 2 Diabetes Mellitus: A Pilot Study

Background Type 2 diabetes mellitus (T2DM) is associated with changes in skeletal muscle quantity and quality, such as increased ectopic fat. Cardiac rehabilitation (CR) aims to improve the exercise capacity and muscle strength. This study aimed to determine the relationship between qualitative changes in the skeletal muscles and exercise function in patients with and without diabetes mellitus. Methods The study included patients with cardiovascular diseases who entered CR. Of 72 CR patients (68.1±9.0 years) who underwent a cardiopulmonary exercise test and skeletal muscle assessment at discharge, 15 patients with T2DM and 15 without DM were selected using propensity score matching by age and gender. Results No significant differences in the skeletal muscle echo intensity (EI) (T2DM: 58.4, Non-DM: 53.4, p=0.32), skeletal muscle index (T2DM: 7.5 kg/m2, Non-DM: 7.2 kg/m2, p=0.36), or the weight-bearing index (WBI)(T2DM: 0.44, Non-DM: 0.50, p=0.35) existed between the two groups. The phase angle (PhA) (T2DM: 3.67°, Non-DM: 4.49°, p<0.05) and peak oxygen uptake (T2DM: 12.3 mL/kg/min, Non-DM: 14.8 mL/kg/min, p<0.05) were significantly lower in the T2DM group. PhA values showed a significant correlation with the WBI, a parameter of lower limb muscle strength (r=0.50, p<0.05). Conclusion The coexistence of cardiovascular disease and T2DM resulted in a decrease in the PhA, indicating a qualitative decrease in skeletal muscle mass. The PhA is also associated with lower limb muscle strength.

Relationship Between Increased Oxygen Uptake and Lactate Production With Progressive Incremental Electrode Skeletal Muscle Stimulation: A Pilot Study

Background Belt electrode skeletal muscle stimulation (B-SES) is an alternative exercise therapy for those with difficulty performing voluntary exercise. However, it is unknown whether oxygen uptake (VO2) in B-SES is comparable to cardiopulmonary exercise test (CPX) as assessed by voluntary exercise. This study aimed to evaluate oxygen uptake (VO2) and lactate (LA) production in incremental B-SES compared to ergometer CPX and to determine the relationship with ergometer CPX. Methods This study included 10 healthy young Japanese participants. Using a crossover design, all participants underwent incremental B-SES CPX and ergometer CPX using a 20 W ramp. Serum lactic acid concentration (LA) was measured serially before, during, and after B-SES. The tolerability of B-SES was adjusted with the change in LA level (⊿LA). Results Peak VO2 during B-SES (14.1±3.3 mL/kg/min) was significantly lower than ergometer peak VO2 (30.2±6.2 mL/kg/min, P<0.001). B-SES peak VO2 was similar to the anaerobic threshold (AT) VO2 on ergometer CPX (15.1±2.6 mL/kg/min). LA (Rest: 1.4±0.3, Peak: 2.8±0.8 mmol) and plasma noradrenalin (Rest: 0.2±0.1, Peak: 0.4±0.1 ng/mL) levels increased after B-SES. No significant correlation was observed between B-SES peak VO2 and ergometer CPX. However, after adjusting for B-SES, tolerability, it (peak VO2 of B-SES /⊿LA) correlated with peak VO2 (r=0.688, p=0.028) on the ergometer. Conclusion Peak VO2 of the passively progressive B-SES almost reached the AT value of the ergometer CPX without adverse events. Peak VO2 of B-SES adjusted with ⊿LA may be used to predict peak VO2 in ergometer CPX.

Successful Transvenous Implantation of a Permanent Pacemaker in a Patient with Situs Inversus with Dextrocardia Supported by Preceding Three-dimensional Computed Tomography: A Case Report

We herein report a 76-year-old woman with situs inversus and dextrocardia who underwent pacemaker implantation for sick sinus syndrome. Situs inversus with dextrocardia, which is frequently associated with cardiovascular malformation, is a rare congenital malformation wherein the thoracic and abdominal viscera are inverted compared with their normal positions. This renders the implantation of cardiac devices an arduous task. We therefore decided to gather preoperative anatomical information on patients with situs inversus and dextrocardia. We used three-dimensional computed tomography to collect preoperative information in order to facilitate the safe implantation of cardiac devices.

Exploring the Multifaceted Nexus of Uric Acid and Health: A Review of Recent Studies on Diverse Diseases

The prevalence of patients with hyperuricemia or gout is increasing worldwide. Hyperuricemia and gout are primarily attributed to genetic factors, along with lifestyle factors like consuming a purine-rich diet, alcohol and/or fructose intake, and physical activity. While numerous studies have reported various comorbidities linked to hyperuricemia or gout, the range of these associations is extensive. This review article focuses on the relationship between uric acid and thirteen specific domains: transporters, genetic factors, diet, lifestyle, gout, diabetes mellitus, metabolic syndrome, atherosclerosis, hypertension, kidney diseases, cardiovascular diseases, neurological diseases, and malignancies. The present article provides a comprehensive review of recent developments in these areas, compiled by experts from the Young Committee of the Japanese Society of Gout and Uric and Nucleic Acids. The consolidated summary serves to enhance the global comprehension of uric acid-related matters.

Uric acid and neurological disease: a narrative review

Hyperuricemia often accompanies hypertension, diabetes, dyslipidemia, metabolic syndrome, and chronic renal disease; it is also closely related to cardiovascular disease. Moreover, several epidemiological studies have linked hyperuricemia and ischemic stroke. However, uric acid may also have neuroprotective effects because of its antioxidant properties. An association between low uric acid levels and neurodegenerative diseases has been suggested, which may be attributed to diminished neuroprotective effects as a result of reduced uric acid. This review will focus on the relationship between uric acid and various neurological diseases including stroke, neuroimmune diseases, and neurodegenerative diseases. When considering both the risk and pathogenesis of neurological diseases, it is important to consider the conflicting dual nature of uric acid as both a vascular risk factor and a neuroprotective factor. This dual nature of uric acid is important because it may help to elucidate the biological role of uric acid in various neurological diseases and provide new insights into the etiology and treatment of these diseases.

Dysuricemia-A New Concept Encompassing Hyperuricemia and Hypouricemia

The importance of uric acid, the final metabolite of purines excreted by the kidneys and intestines, was not previously recognized, except for its role in forming crystals in the joints and causing gout. However, recent evidence implies that uric acid is not a biologically inactive substance and may exert a wide range of effects, including antioxidant, neurostimulatory, proinflammatory, and innate immune activities. Notably, uric acid has two contradictory properties: antioxidant and oxidative ones. In this review, we present the concept of "dysuricemia", a condition in which deviation from the appropriate range of uric acid in the living body results in disease. This concept encompasses both hyperuricemia and hypouricemia. This review draws comparisons between the biologically biphasic positive and negative effects of uric acid and discusses the impact of such effects on various diseases.

Association between psychomotor function and ALDH2 genotype after consuming barley shochu: A randomized crossover trial

Sustained exposure to acetaldehyde, the major metabolite of ethanol, may influence psychomotor performance even after the breath ethanol level significantly drops several hours following ethanol consumption. We examined the relationship between psychomotor function and changes in exhaled ethanol and acetaldehyde concentrations after consuming a low dose (0.33 g/kg) of barley shochu, a traditional Japanese distilled alcohol beverage, at the point when the exhaled ethanol concentrations dropped below 78,000 parts per billion (0.15 mg/L), the standard threshold for driving under the influence of alcohol in Japan. We assessed how the genetic polymorphisms of rs671 G/G homozygous (*1/*1) and G/A heterozygous (*1/*2) of ALDH2 influenced the kinetics of ethanol and acetaldehyde in exhaled air and psychomotor dynamics using the Digit Symbol Substitution Test (DSST), Critical Flicker Fusion Test (CFFT), and visual analogue scale (VAS) up to 12 h after shochu or water intake. There was no significant difference in DSST and CFFT scores depending on genotype; however, the time required for the DSST to attain the level prior to drinking was longer in the ALDH2 *1/*2 group than in the *1/*1 group. In the VAS test, facial flushing and mood elevation tended to be higher in the *1/*2 group after shochu consumption. VAS scores for mood elevation and facial flushing correlated with acetaldehyde concentration in exhaled breath. These results indicate that DSST recovery tends to be slower and mood elevation higher in the ALDH2 *1/*2 group even when exposed to a low dose of alcohol.

Recent Advances in the Treatment of Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a disease in which stenosis or obstruction of the pulmonary arteries (PAs) causes an increase in PA pressure, leading to right-sided heart failure and death. Basic research has revealed a decrease in the levels of endogenous vasodilators, such as prostacyclin, and an increase in the levels of endogenous vasoconstrictors, such as endothelin, in patients with PAH, leading to the development of therapeutic agents. Currently, therapeutic agents for PAH target three pathways that are selective for PAs: the prostacyclin, endothelin, and nitric oxide pathways. These treatments improve the prognosis of PAH patients. In this review, we introduce new drug therapies and provide an overview of the current therapeutic agents.

Glibenclamide attenuates brain edema associated with microglia activation after intracerebral hemorrhage

OBJECTIVE

Glibenclamide, Sulfonylurea receptor 1 antagonist, reduces brain edema after cerebral hemorrhage. However, the effects of glibenclamide on microglial activation and inflammatory cell infiltration after cerebral hemorrhage are unclear. The present study investigated the effect of glibenclamide on microglial activation and inflammatory cell infiltration in a rat cerebral hemorrhage model.

METHODS

A collagenase intracerebral injection model was used to cause cerebral hemorrhage in rats. After injury, glibenclamide was continuously administered at 1.0μL/h for 24hours. We evaluated hematoma volume, brain edema, expression of ABCC8, galectin-3 and CD11b, and anti-Iba-1 antibody staining.

RESULTS

Glibenclamide significantly reduced water content. Meanwhile, glibenclamide significantly reduced expression of galectin-3 and CD11b in the cerebral cortex and putamen on the bleeding side. Immunohistochemical staining confirmed that glibenclamide attenuated activation of microglia around the hematoma.

CONCLUSIONS

Glibenclamide reduced microglial activation and infiltration of inflammatory cells, resulting in amelioration of cerebral edema.

Pharmacokinetics of lanoconazole in human skin after repeated topical application

Drug disposition after topical application to the skin has not been fully elucidated, especially after repeated application. We conducted a clinical trial to evaluate the pharmacokinetics in the stratum corneum of healthy adults after repeated application of lanoconazole cream as a model drug. We applied 25 mg of 1% lanoconazole cream onto the pre-specified areas on the participants' back once daily for 5 days. The stratum corneum was sampled twice on each study day using a standardized tape-stripping method, and the amount of lanoconazole contained in the samples was quantified using the tandem mass spectrometry method. The obtained data were used to evaluate lanoconazole pharmacokinetics in the stratum corneum. The amount of lanoconazole in the stratum corneum after once daily repeated administration reached a steady state on day 3, and it was eliminated from the stratum corneum with a half-life of approximately 11 h after discontinuing application.

A Phase 1 Study to Evaluate Safety, Pharmacokinetics, and Pharmacodynamics of Respiratory Syncytial Virus (RSV) Neutralizing Monoclonal Antibody MK-1654 in Healthy Japanese Adults

Respiratory syncytial virus (RSV) is the leading cause of lower respiratory tract infection among all infants worldwide and remains a significant cause of morbidity and mortality. To address this unmet medical need, MK‐1654, a half‐life extended RSV neutralizing monoclonal antibody, is in clinical development for the prevention of RSV disease in infants. This was a phase I, randomized, placebo‐controlled, single‐site, double‐blind trial of MK‐1654 in 44 healthy Japanese adults. The safety, tolerability, pharmacokinetics, antidrug antibodies (ADAs), and serum neutralizing antibody (SNA) titers against RSV were evaluated for 1 year after a single intramuscular (i.m.) or intravenous (i.v.) dose of MK‐1654 or placebo in five groups (100 mg i.m., 300 mg i.m., 300 mg i.v., 1000 mg i.v., or placebo). MK‐1654 was generally well‐tolerated in Japanese adults. There were no serious drug‐related adverse events (AEs) reported in any MK‐1654 recipient and no discontinuations due to any AEs in the study. The half‐life of MK‐1654 ranged from 76 to 91 days across dosing groups. Estimated bioavailability was 86% for 100 mg i.m. and 77% for 300 mg i.m. One participant out of 33 (3.0%) developed detectable ADA with no apparent associated AEs. The RSV SNA titers increased in a dose‐dependent manner among participants who received MK‐1654. These data support the development of MK‐1654 for use in Japanese infants.

Hypouricemia and Urate Transporters

Hypouricemia is recognized as a rare disorder, defined as a serum uric acid level of 2.0 mg/dL or less. Hypouricemia is divided into an overexcretion type and an underproduction type. The former typical disease is xanthinuria, and the latter is renal hypouricemia (RHUC). The frequency of nephrogenic hypouricemia due to a deficiency of URAT1 is high in Japan, accounting for most asymptomatic and persistent cases of hypouricemia. RHUC results in a high risk of exercise-induced acute kidney injury and urolithiasis. It is vital to promote research on RHUC, as this will lead not only to the elucidation of its pathophysiology but also to the development of new treatments for gout and hyperuricemia.

Evidence for Urate Uptake Through Monocarboxylate Transporter 9 Expressed in Mammalian Cells and Its Enhancement by Heat Shock

Background: Monocarboxylate transporter 9 (MCT9), an orphan transporter member of the solute carrier family 16 (SLC16), possibly reabsorbs uric acid in the renal tubule and has been suggested by genome-wide association studies to be involved in the development of hyperuricemia and gout. In this study we investigated the mechanisms regulating the expression of human (h) MCT9, its degradation, and physiological functions. Methods and Results: hMCT9-FLAG was stably expressed in HEK293 cells and its degradation, intracellular localization, and urate uptake activities were assessed by pulse-chase analysis, immunofluorescence, and [¹⁴C]-urate uptake experiments, respectively. hMCT9-FLAG was localized on the plasma membrane as well as in the endoplasmic reticulum and Golgi apparatus. The proteasome inhibitors MG132 and lactacystine increased levels of hMCT9-FLAG protein expression with enhanced ubiquitination, prolonged their half-life, and decreased [¹⁴C]-urate uptake. [¹⁴C]-urate uptake was increased by both heat shock (HS) and the HS protein inducer geranylgeranylacetone (GGA). Both HS and GGA restored the [¹⁴C]-urate uptake impaired by MG132. Conclusions: hMCT9 does transport urate and is degraded by a proteasome, inhibition of which reduces hMCT9 expression on the cell membrane and urate uptake. HS enhanced urate uptake through hMCT9.

Recent approaches to gout drug discovery: an update

INTRODUCTION

Inflammation induced by urate deposition in joints causes gout. Healthy individuals maintain serum levels of urate by balancing urate production/excretion, whereas a production/excretion imbalance increases urate levels. Hyperuricemia is diagnosed when the serum urate level is continuously above 7 mg/dl as the solubility limit, and urate accumulates in the kidneys and joints. Because hyperuricemia increases the risk of gout, therapies aim to eliminate urate deposition to prevent gouty arthritis and kidney injury.

AREAS COVERED

This review discusses the mechanism underlying hyperuricemia with respect to urate production and urate transport, along with urate-lowering therapeutics, including urate synthesis inhibitors, uricolytic enzymes, and uricosuric agents. The authors asses published data on relevant commercial therapy development projects and clinical trials.

EXPERT OPINION

Available treatment options for hyperuricemia are limited. Allopurinol, a urate synthesis inhibitor, is generally administered at a reduced dosage to patients with renal impairment. Some URAT1 inhibitors have an unfavorable side effect profile. A promising strategy for treatment is the use of uricosuric agents that inhibit transporters (e.g. URAT1, URATv1/GLUT9, OAT10) which reabsorb urate from the urine.

Effects of Anticholinergic Drugs Used for the Therapy of Overactive Bladder on P-Glycoprotein Activity

We evaluated the effects of anticholinergic drugs principally used for the therapy of overactive bladder (OAB) on the activity of P-glycoprotein, an efflux transport protein, in Caco-2 cells. The time-dependent changes in the fluorescence of residual rhodamine 123, a P-glycoprotein activity marker, in the apical region of Caco-2 cells were measured in the presence of anticholinergic drugs using time-lapse confocal laser scanning microscopy. The effect of anticholinergic drugs on human P-glycoprotein ATPase activity was also measured. The fluorescence of residual rhodamine 123 in untreated Caco-2 cells decreased over time. The gradual decrease in the fluorescence was significantly inhibited by treatment with cyclosporine A, darifenacin, and trospium. In contrast, oxybutynin, N-desethyl-oxybutynin (DEOB), propiverine, and its active metabolites (M-1, M-2), imidafenacin, solifenacin, or tolterodine had little effect on the efflux of rhodamine 123. P-Glycoprotein ATPase activity was increased by darifenacin. Darifenacin and trospium reduced the rhodamine 123 transfer across the apical cell membrane. These data suggest that darifenacin and trospium interact with P-glycoprotein. Additionally, darifenacin influenced P-glycoprotein ATPase activity. These results suggest that darifenacin may be a substrate of P-glycoprotein. This study is the first paper to test simultaneously the effects of 10 anticholinergic drugs used currently for the therapy of OAB, on the P-glycoprotein.

No Effect of Digoxin on Rosuvastatin Pharmacokinetics in Healthy Subjects: Utility of Oita Combination for Clinical Drug-Drug Interaction Study

This study evaluated the utility of combination of digoxin (0.25 mg) and rosuvastatin (5 mg) as a new transporter (P-glycoprotein/breast cancer resistance protein/organic anion-transporting polypeptide (OATP)1B1/OATP1B3) probe cocktail (Oita combination) for drug-drug interaction (DDI) studies by demonstrating lack of DDI of digoxin on the pharmacokinetics (PKs) of rosuvastatin, as it was already known that rosuvastatin did not affect digoxin PK. This was an open-label, two-period study in which the primary end points were the geometric mean ratio (GMR) of the area under the plasma rosuvastatin concentration-time curve from time zero to last (AUC_last ) after rosuvastatin administration combined with digoxin to that after rosuvastatin administration alone and its 90% confidence interval (CI). As the GMR of AUC_last was 0.974 and its 90% CI was 0.911-1.042, it was judged that digoxin does not affect rosuvastatin PK. Results of this study have rationalized utility of the Oita combination as a transporter probe cocktail for clinical DDI studies.

Uric acid lowering in relation to HbA1c reductions with the SGLT2 inhibitor tofogliflozin

An integrated analysis was performed with data from 4 phase 2 and phase 3 studies of tofogliflozin in which patients with type 2 diabetes mellitus received the sodium-glucose cotransporter 2 inhibitor tofogliflozin for up to 24 weeks. Sex differences, baseline haemoglobin A1c (HbA1c) and serum uric acid (UA) levels, and log₁₀ -transformed urinary N-acetyl-β-D-glucosaminidase ratio were significantly correlated with the reduction in serum UA levels at both 4 and 24 weeks in multivariate analysis (respectively, P < .0001). The decrease in HbA1c levels was greatest in the group with the highest baseline HbA1c level (quartile 4; HbA1c > 8.6%) and lowest in the group with the lowest baseline HbA1c level (quartile 1; HbA1c ≤ 7.4%). The decrease in serum UA levels was greatest in the quartile 1 group and lowest in the quartile 4 group. In most groups, the maximum decrease in serum UA levels was seen in the first 4 weeks, while the maximum decrease in HbA1c was seen at week 24. Thus, serum UA levels were significantly decreased in patients with moderate HbA1c levels.

Cardiac paraganglioma with a novel germline mutation of succinate dehydrogenase gene D

A 58-year-old woman with a past medical history of a carotid body tumor, resected 4 months prior to presentation, was admitted to our hospital for treatment of a cardiac tumor that was identified on post-operative echocardiography and chest computed tomography. The cardiac tumor was surgically removed and identified pathologically as a paraganglioma, similarly to the carotid body tumor. Genetic analysis of both tumors identified a non-synonymous mutation in the succinate dehydrogenase (SDH) gene D, Exon4, c.320T>C, p.Leu107Pro showing co-segregation with paternal transmission and maternal imprinting among family members. This novel mutation appears to be the cause of familial paraganglioma in this patient.

Protective Effects of Topiroxostat on an Ischemia-Reperfusion Model of Rat Hearts

BACKGROUND

Ischemia/reperfusion (I/R) injury triggers cardiac dysfunctions via creating reactive oxygen species (ROS). Because xanthine oxidase (XO) is one of the major enzymes that generate ROS, inhibition of XO is expected to suppress ROS-induced I/R injury. However, it remains unclear whether XO inhibition really yields cardioprotection during I/R. The protective effects of the XO inhibitors, topiroxostat and allopurinol, on cardiac I/R injury were evaluated.Methods and Results:Using isolated rat hearts, ventricular functions, occurrence of arrhythmias, XO activities and thiobarbituric acid reactive substances (TBARS) productions and myocardial levels of adenine nucleotides before and after I/R, and cardiomyocyte death markers during reperfusion, were evaluated. Topiroxostat prevented left ventricular dysfunctions and facilitated recovery from arrhythmias during I/R. Allopurinol and the antioxidant, N-acetylcysteine (NAC), exhibited similar effects at higher concentrations. Topiroxostat inhibited myocardial XO activities and TBARS productions after I/R. I/R decreased myocardial levels of ATP, ADP and AMP, but increased that of xanthine. While topiroxostat, allopurinol or NAC did not change myocardial levels of ATP, ADP or AMP after I/R, all of the agents decreased the level of xanthine. They also decreased releases of CPK and LDH during reperfusion.

CONCLUSIONS

Topiroxostat showed protective effects against I/R injury with higher potency than allopurinol or NAC. It dramatically inhibited XO activity and TBARS production, suggesting suppression of ROS generation.

Reproducible insulin secretion from isolated rat pancreas preparations using an organ bath

Diabetes mellitus is a lifestyle-related disease that is characterized by inappropriate or diminished insulin secretion. Ex vivo pharmacological studies of hypoglycemic agents are often conducted using perfused pancreatic preparations. Pancreas preparations for organ bath experiments do not require cannulation and are therefore less complex than isolated perfused pancreas preparations. However, previous research has generated almost no data on insulin secretion from pancreas preparations using organ bath preparations. The purpose of this study was to investigate the applicability of isolated rat pancreas preparations using the organ bath technique in the quantitative analysis of insulin secretion from β-cells. We found that insulin secretion significantly declined during incubation in the organ bath, whereas it was maintained in the presence of 1 µM GLP-1. Conversely, amylase secretion exhibited a modest increase during incubation and was not altered in the presence of GLP-1. These results demonstrate that the pancreatic organ bath preparation is a sensitive and reproducible method for the ex vivo assessment of the pharmacological properties of hypoglycemic agents.

Molecular mechanisms underlying the pilsicainide-induced stabilization of hERG proteins in transfected mammalian cells

Background

Pilsicainide, classified as a relatively selective Na⁺ channel blocker, also has an inhibitory action on the rapidly-activating delayed-rectifier K⁺ current (I_Kr) through human ether-a-go-go-related gene (hERG) channels. We studied the effects of chronic exposure to pilsicainide on the expression of wild-type (WT) hERG proteins and WT-hERG channel currents, as well as on the expression of mutant hERG proteins, in a heterologous expression system.

Methods

HEK293 cells stably expressing WT or mutant hERG proteins were subjected to Western blotting, immunofluorescence microscopy and patch-clamp experiments.

Results

Acute exposure to pilsicainide at 0.03–10 μM influenced neither the expression of WT-hERG proteins nor WT-hERG channel currents. Chronic treatment with 0.03–10 μM pilsicainide for 48 h, however, increased the expression of WT-hERG proteins and channel currents in a concentration-dependent manner. Chronic treatment with 3 μM pilsicainide for 48 h delayed degradation of WT-hERG proteins and increased the channels expressed on the plasma membrane. A cell membrane-impermeant pilsicainide derivative did not influence the expression of WT-hERG, indicating that pilsicainide stabilized the protein inside the cell. Pilsicainide did not influence phosphorylation of Akt (protein kinase B) or expression of heat shock protein families such as HSF-1, hsp70 and hsp90. E4031, a chemical chaperone for hERG, abolished the pilsicainide effect on hERG. Chronic treatment with pilsicainide could also increase the protein expression of trafficking-defective mutant hERG, G601S and R752W.

Conclusions

Pilsicainide penetrates the plasma membrane, stabilizes WT-hERG proteins by acting as a chemical chaperone, and enhances WT-hERG channel currents. This mechanism could also be applicable to modulations of certain mutant-hERG proteins.

Erratum to: 36th International Symposium on Intensive Care and Emergency Medicine: Brussels, Belgium. 15-18 March 2016

[This corrects the article DOI: 10.1186/s13054-016-1208-6.].

Impact of Obstructive Sleep Apnoea on Heart Failure with Preserved Ejection Fraction

BACKGROUND

The impact of obstructive sleep apnoea on heart failure with preserved ejection fraction is unknown.

METHODS

Fifty-eight patients who had heart failure with a left ventricular ejection fraction; ≥50% underwent a sleep study. Brain natriuretic peptide (BNP) levels were determined at enrolment and at one, six, 12 and 36 months after enrolment.

RESULTS

Obstructive sleep apnoea was found in 39 patients (67%), and they were all subsequently treated with continuous positive airway pressure. Echocardiography at admission showed that E/E' tended to be higher in the 39 patients with, than in the 19 patients without, obstructive sleep apnoea (15.0±3.6 vs 12.1±1.9, respectively, P=0.05). The median BNP levels at enrolment were similar in patients with and without obstructive sleep apnoea [median (interquartile range): 444 (233-752) vs 316 (218-703) pg/ml]. Although BNP levels decreased over time in both groups, the reduction was less pronounced in patients with obstructive sleep apnoea (P<0.05). Consequently, BNP levels were higher in patients with sleep apnoea at six months, [221 (137-324) vs 76 (38-96) pg/ml, P<0.05], 12 months [123 (98-197) vs 52 (38-76) pg/ml, P<0.05] and 36 months [115 (64-174) vs 56 (25-74) pg/ml, P<0.05].

CONCLUSION

Obstructive sleep apnoea, even when treated appropriately, may worsen long-term cardiac function and outcomes in patients who have heart failure with preserved ejection fraction.

Protective effect of K201 on isoproterenol-induced and ischemic-reperfusion-induced ventricular arrhythmias in the rat: comparison with diltiazem

AIM

Ventricular arrhythmia (VA) is a risk for sudden death. Polymorphic ventricular tachycardia (VT) degenerating to ventricular fibrillation occurs subsequent to the prolongation of the QT interval following administration of catecholamines under Ca(2+) loading. Fatal VA also occurs in ischemia and ischemic-reperfusion. We compared the suppressive effect of K201 (JTV519), a multiple-channel blocker and cardiac ryanodine receptor-calcium release channel (RyR2) stabilizer, with that of diltiazem, a Ca(2+ )channel blocker, in 2 studies of isoproterenol-induced (n = 30) and ischemic-reperfusion-induced VAs (n = 38) in rats.

METHODS

Adult male Wistar rats were administered 12 mg/kg/min calcium chloride (CaCl(2)) for 20 minutes and then 6 μg/kg/min isoproterenol was infused with CaCl(2) for a further 20 minutes. In other rats, the left coronary artery was ligated for 5 minutes followed by reperfusion for 20 minutes. K201 or diltiazem (both 1 mg/kg) was administered before infusion of the isoproterenol or induction of ischemia.

RESULTS

After administration of isoproterenol under Ca(2+) loading, fatal VA frequently occurred in the vehicle (9 of 10 animals, 90%) and diltiazem (8 of 10, 80%) groups, and K201 significantly suppressed the incidences of arrhythmia and mortality (2 of 10, 20%). In the reperfusion study, the incidence and the time until occurrence of reperfusion-induced VA and mortality were significantly suppressed in the K201 (2 of 15 animals, 13%) and diltiazem (1 of 9 animals, 11%) groups compared to the vehicle group (8 of 14 animals, 57%).

SIGNIFICANCE

Induction of VA in an experimental model was achieved with a low dose of isoproterenol under Ca(2+) loading. K201 markedly suppressed both the isoproterenol-induced and the reperfusion-induced VAs, whereas diltiazem did not suppress the isoproterenol-induced VA. The results suggest that both VAs are related to early after depolarization (EAD) and indicate that K201 has the potential to suppress EAD by stabilizing RyR2 to mediate Ca(2+) release from the sarcoplasmic reticulum and acting as a multiple-channel blocker.

Left ventricular function in pulmonary hypertension

To elucidate left ventricular function in pulmonary hypertension, we measured parameters of left ventricular as well as right ventricular function by echocardiography in 11 patients with pulmonary hypertension (idiopathic pulmonary artery hypertension in 4, chronic thromboembolic pulmonary hypertension in 5, and other pulmonary hypertension in 2). The percent change in these parameters 6 months after treatment with pulmonary artery vasodilators (beraprost in 8 and sildenafil in 3) was assessed. There was a correlation between the relative change in right ventricular systolic pressure (RVSP) and the relative changes in left ventricular outflow tract velocity-time integral (r = -0.730, P = 0.011) and mitral valve velocity-time integral (r = -0.621, P = 0.041). However, there was no correlation between the relative change in RVSP and the relative changes in left ventricular ejection fraction, left ventricular diastolic dimension, and systolic blood pressure. The relative change in RVSP was also correlated with the relative change in early diastolic myocardial velocity at the medial mitral annulus (r = -0.675, P = 0.023). Reduction of RVSP by pulmonary artery vasodilators might increase left ventricular preload, leading to an increase in stroke volume. Right ventricular load reduction might improve left ventricular diastolic function in patients with pulmonary hypertension, possibly through altered interventricular septal performance.

Experimental venous thrombi: MRI characteristics with histopathological correlation

OBJECTIVES

The purpose of this study was to evaluate the MRI characteristics of venous thrombus over set time thresholds with histopathological correlation in a porcine model.

METHODS

Inferior vena cava thrombi were induced in 12 pigs. MRI was performed in three pigs 2 h, 1 day, 3 days and 2 weeks after thrombus induction.

RESULTS

The MRI characteristics were analysed in correlation with histopathological findings. The thrombi after 2 hours, which consisted of red blood cells (RBCs), showed isointensity on T(1 )weighted images (T(1)WIs) and hyperintensity on both T(2 )weighted images (T(2)WIs) and diffusion-weighted images (DWIs). The mean apparent diffusion coefficient (ADC) value was 1.93 × 10(-3) mm(2) s(-1). The thrombi after Day 1, which consisted of RBCs and migrating neutrophils at the periphery, showed isointensity on T(1)WIs, slight hyperintensity on T(2)WIs and hypointensity on DWIs. The mean ADC value was 1.62 × 10(-3) mm(2) s(-1) [corrected]. The thrombi after Day 3, which consisted of RBCs and peripheral inflammatory cells including macrophages, showed isointensity with peripheral hyperintense regions on T(1)WIs and hypointensity on both T(2)WIs and DWIs. The mean ADC value was 1.67 × 10(-3) mm(2) s(-1). After 2 weeks, the thrombi, which revealed RBC lysis surrounded by granulation tissues, showed isointensity on T(1)WIs and hyperintensity on T(2)WIs and DWIs. The mean ADC value was 2.48 × 10(-3) mm(2) s(-1).

CONCLUSION

The temporal MRI characteristics seemed to be related to chemical and physical changes in RBC and organisation of granulation tissues. Free radicals generated by macrophages might also be related to some extent.

K201 (JTV-519) alters the spatiotemporal properties of diastolic Ca(2+) release and the associated diastolic contraction during β-adrenergic stimulation in rat ventricular cardiomyocytes

K201 has previously been shown to reduce diastolic contractions in vivo during β-adrenergic stimulation and elevated extracellular calcium concentration ([Ca²⁺]_o). The present study characterised the effect of K201 on electrically stimulated and spontaneous diastolic sarcoplasmic reticulum (SR)-mediated Ca²⁺ release and contractile events in isolated rat cardiomyocytes during β-adrenergic stimulation and elevated [Ca²⁺]_o. Parallel experiments using confocal microscopy examined spontaneous diastolic Ca²⁺ release events at an enhanced spatiotemporal resolution. 1.0 μmol/L K201 in the presence of 150 nmol/L isoproterenol (ISO) and 4.75 mmol/L [Ca²⁺]_o significantly decreased the amplitude of diastolic contractions to ~16% of control levels. The stimulated free Ca²⁺ transient amplitude was significantly reduced, but stimulated cell shortening was not significantly altered. When intracellular buffering was taken into account, K201 led to an increase in action potential-induced SR Ca²⁺ release. Myofilament sensitivity to Ca²⁺ was not changed by K201. Confocal microscopy revealed diastolic events composed of multiple Ca²⁺ waves (2–3) originating at various points along the cardiomyocyte length during each diastolic period. 1.0 μmol/L K201 significantly reduced the (a) frequency of diastolic events and (b) initiation points/diastolic interval in the remaining diastolic events to 61% and 71% of control levels respectively. 1.0 μmol/L K201 can reduce the probability of spontaneous diastolic Ca²⁺ release and their associated contractions which may limit the propensity for the contractile dysfunction observed in vivo.

Campylobacter fetus as cause of prosthetic valve endocarditis

A 65-year-old woman who had previously undergone aortic root replacement with a bioprosthetic valve (Bentall operation) in treatment of annuloaortic ectasia became feverish after developing dental caries and was admitted to our hospital. Transesophageal echocardiography showed an 18 × 4-mm vegetation on her prosthetic valve. Campylobacter fetus was isolated on blood cultures, and she was diagnosed with infectious endocarditis. Aggressive combined antibiotic treatment was effective for her recovery. C. fetus infection is a rarely reported cause of prosthetic valve endocarditis.

K201 modulates excitation–contraction coupling and spontaneous Ca2+ release in normal adult rabbit ventricular cardiomyocytes

OBJECTIVES

The drug K201 (JTV-519) increases inotropy and suppresses arrhythmias in failing hearts, but the effects of K201 on normal hearts is unknown.

METHODS

The effect of K201 on excitation-contraction (E-C) coupling in normal myocardium was studied by using voltage-clamp and intracellular Ca(2+) measurements in intact cells. Sarcoplasmic reticulum (SR) function was assessed using permeabilised cardiomyocytes.

RESULTS

Acute application of <1 micromol/L K201 had no significant effect on E-C coupling. K201 at 1 micromol/L decreased Ca(2+) transient amplitude (to 83+/-7%) without affecting I(Ca,L) or the SR Ca(2+) content. At 3 micromol/L K201 caused a larger reduction of Ca(2+) transient amplitude (to 60+/-7%) with accompanying reductions in I(Ca,L) amplitude (to 66+/-8%) and SR Ca(2+) content (74+/-9%). Spontaneous SR Ca(2+) release during diastole was induced by increasing intracellular [Ca(2+)]. At 1 micromol/L K201 reduced the frequency of spontaneous Ca(2+) release. The effect of K201 on SR-mediated Ca(2+) waves and Ca(2+) sparks was examined in beta-escin-permeabilised cardiomyocytes by confocal microscopy. K201 (1 micromol/L) reduced the frequency and velocity of SR Ca(2+) waves despite no change in SR Ca(2+) content. At 3 micromol/L K201 completely abolished Ca(2+) waves and reduced the SR Ca(2+) content (to approximately 73%). K201 at 1 micromol/L reduced Ca(2+) spark amplitude and frequency. Assays specific to SR Ca(2+)-ATPase and RyR2 activity indicated that K201 inhibited both SR Ca(2+) uptake and release.

CONCLUSIONS

K201 modifies E-C coupling in normal cardiomyocytes. A dual inhibitory action on SERCA and RyR2 explains the ability of K201 to suppress spontaneous diastolic Ca(2+) release during Ca(2+) overload without significantly affecting Ca(2+) transient amplitude.