Histopathological characteristics of the arrhythmogenic right ventricular cardiomyopathy presenting the electrocardiographic characteristics with Brugada syndrome

INTRODUCTION

The histopathological characteristics of the overlapping disease states of Brugada syndrome (BrS) and arrhythmogenic right ventricular cardiomyopathy (ARVC) have not been fully elucidated.

METHODS

A 71-year-old man showed coved-type ST-segment elevation with the right precordial leads, and the echocardiography demonstrated right ventricular (RV) dilatation. After 11 months, he died of a polymorphic VT storm.

RESULTS

The pathological tissue demonstrated fibrofatty degeneration in the free wall of the RV outflow tract based on the heart autopsy.

CONCLUSION

The overlapping disease states of BrS and ARVC showed histopathological characteristics consistent with ARVC.

The characteristics and efficacy of catheter ablation of focal atrial tachycardia arising from an epicardial site

BACKGROUND

Although epicardial structures around the atrium such as adipose tissue possess arrhythmogenicity, little is known about atrial tachycardias (ATs) originating from epicardial sites (Epi-ATs). This study aimed to elucidate the prevalence, characteristics, and outcome after radiofrequency catheter ablation (RFCA) of Epi-ATs and to reveal the association between Epi-ATs and the epicardial structures.

METHODS

The electrocardiographic, electrophysiologic, and anatomical properties and results of RFCA were analyzed in 42 patients with a total of 49 ectopic ATs.

RESULTS

Six Epi-ATs (12%) were observed in six patients (14%). Four of six were respiratory cycle-dependent ATs and one was a swallowing-induced AT. The Epi-AT origins were adjacent to a pulmonary vein (five cases) and vein of Marshall (one case). A Valsalva maneuver or atropine infusion to define the arrhythmia mechanism affected the appearance of the Epi-ATs. The congruity rate between epicardial adipose tissue and the AT origin was significantly higher (100% vs. 44%, p = .045), and the epicardial adipose tissue volume of the atrium was significantly larger (104.1 vs. 64.6 ml, p = .04) in the Epi-AT group. Endocardial RFCA targeting the AT foci resulted in acute success in five of five cases. However, electrical isolation including of the AT foci resulted in acute failures (two of three cases) or a recurrence (one of one case).

CONCLUSIONS

Six Epi-ATs were associated with thoracic veins and epicardial arrhythmogenic structures. The main cause provoking the Epi-ATs was associated with autonomic nerve activity.

Autopsy evaluation of the implantation site of a His bundle pacing lead demonstrating selective capture

Evaluations of His bundle pacing (HBP) lead location at autopsy examination have been rarely reported. We report an autopsy case of a 98-year-old man who underwent HBP implantation due to atrioventricular block and heart failure. Although selective HBP was achieved with an acceptable threshold, the stimulus-to-QRS interval was relatively longer without correction of the right bundle-branch block. A macroscopic examination revealed that the HBP lead was inserted on the ventricular side passing through the anteroseptal commissure of the tricuspid valve. Transthyretin cardiac amyloidosis may affect the distal conduction system resulting in a long stimulus-to-QRS interval during selective HBP.

Ethanol injection into the Marshall vein provoking a pericardial effusion resulting in a fatal complication in a patient with persistent atrial fibrillation

An EIM (ethanol infusion into the vein of Marshall [VOM]) provoked a fatal complication in a chronic hemodialysis patient. Autopsy revealed a lacerated VOM covered with thrombi as the only potential cause. The EIM caused vascular damage and clots resulting in myocardial necrosis and interstitial bleeding around the lacerated VOM.

Regional Differences in Frequency of Warfarin Therapy and Thromboembolism in Japanese Patients With Non-Valvular Atrial Fibrillation - Analysis of the J-RHYTHM Registry

BACKGROUND

The proportion of patients with atrial fibrillation (AF) treated with anticoagulation varies from country to country. In Japan, little is known about regional differences in frequency of warfarin use or prognosis among patients with non-valvular AF (NVAF).

METHODS AND RESULTS

In J-RHYTHM Registry, the number of patients recruited from each of 10 geographic regions of Japan was based on region population density. A total of 7,406 NVAF patients were followed up prospectively for 2 years. At baseline, significant differences in various clinical characteristics including age, sex, type of AF, comorbidity, and CHADS2score, were detected among the regions. The highest mean CHADS2score was recorded in Shikoku. Frequency of warfarin use differed between the regions (P<0.001), with lower frequencies observed in Hokkaido and Shikoku. Baseline prothrombin time international normalized ratio differed slightly but significantly between the regions (P<0.05). On univariate analysis, frequency of thromboembolic events differed among the regions (P<0.001), with the highest rate seen in Shikoku. An inverse correlation was detected between frequency of thromboembolic and of major hemorrhagic events (P=0.062). On multivariate analysis, region emerged as an independent risk for thromboembolism.

CONCLUSIONS

Thromboembolic risk, frequency of warfarin use, and intensity and quality of warfarin treatment differed significantly between geographic regions of Japan. Region was found to be an independent predictor of thromboembolic events. (Circ J 2016; 80: 1548-1555).

Atypical Fast-Slow Atrioventricular Nodal Reentrant Tachycardia Incorporating a "Superior" Slow Pathway: A Distinct Supraventricular Tachyarrhythmia

BACKGROUND

The existence of an atypical fast-slow (F/S) atrioventricular nodal reentrant tachycardia (AVNRT) including a superior (sup) pathway with slow conductive properties and an atrial exit near the His bundle has not been confirmed.

METHODS AND RESULTS

We studied 6 women and 2 men (age, 74 ± 7 years) with sup-F/S-AVNRT who underwent successful radiofrequency ablation near the His bundle. Programmed ventricular stimulation induced retrograde conduction over a superior SP with an earliest atrial activation near the His bundle, a mean shortest spike-atrial interval of 378 ± 119 milliseconds, and decremental properties in all patients. sup-F/S-AVNRT was characterized by a long-RP interval; a retrograde atrial activation sequence during tachycardia identical to that over a sup-SP during ventricular pacing; ventriculoatrial dissociation during ventricular overdrive pacing of the tachycardia in 5 patients or atrioventricular block occurring during tachycardia in 3 patients, excluding atrioventricular reentrant tachycardia; termination of the tachycardia by ATP; and a V-A-V activation sequence immediately after ventricular induction or entrainment of the tachycardia, including dual atrial responses in 2 patients. Elimination or modification of retrograde conduction over the sup-SP by ablation near the right perinodal region or from the noncoronary cusp of Valsalva eliminated and confirmed the diagnosis of AVNRT in 4 patients each.

CONCLUSIONS

sup-F/S-AVNRT is a distinct supraventricular tachycardia, incorporating an SP located above the Koch triangle as the retrograde limb, that can be eliminated by radiofrequency ablation.

Non-valvular atrial fibrillation patients with low CHADS2 scores benefit from warfarin therapy according to propensity score matching subanalysis using the J-RHYTHM Registry

INTRODUCTION

Recently, direct-acting oral anticoagulants (DOACs) have been introduced, with increasing use in patients with non-valvular atrial fibrillation (NVAF). However, warfarin continues to be widely used and the benefits and risks of warfarin in NVAF patients warrant closer inspection.

MATERIALS AND METHODS

Thromboembolism, major hemorrhage, and total and cardiovascular mortalities were analyzed in 7,406 NVAF patients in the J-RHYTHM Registry from January to July 2009, prior to DOAC introduction. Propensity score matching analysis was performed to reduce the differences in clinical characteristics between non-anticoagulant (n=1002) and warfarin (n=6404) cohorts to reassess warfarin outcomes over 2years.

RESULTS

The incidence of thromboembolism was significantly greater in the non-anticoagulant cohort (3.0%) than in the warfarin cohort (1.5%, P<0.001) with less frequent major hemorrhage in the non-anticoagulant cohort (0.8%) than in the warfarin cohort (2.1%, P=0.009). Using propensity score matching, new subsets (n=896 each) were obtained, with matching of the clinical characteristics between warfarin and non-anticoagulant subsets. The warfarin subset had lower risk factors compared with the total warfarin cohort. The incidence of thromboembolism was higher in the non-anticoagulant subset (2.9%) than in the warfarin subset (0.7%, P<0.001). However, major hemorrhage was not significantly different between the two subsets.

CONCLUSIONS

Although warfarin was associated with a significantly higher incidence of hemorrhage in the unmatched cohorts, propensity score matching revealed that warfarin reduced thromboembolism without a significant increase in hemorrhage in the matched subsets with lower risks. Propensity score matching reduced selection bias and provided rational comparisons although it had indwelling limitations.

Impact of gender on the prognosis of patients with nonvalvular atrial fibrillation

Treatment guidelines for atrial fibrillation (AF) used in Western countries describe female gender as a risk factor for thromboembolic events in patients with nonvalvular AF (NVAF). The present study aimed to determine the impact of gender on prognosis of Japanese patients with NVAF. A subanalysis of 7,406 patients with NVAF (mean age 70 years) who were followed-up prospectively for 2 years was performed using data from the J-RHYTHM registry. The primary end points were thromboembolic events, major hemorrhaging, total mortality, and cardiovascular mortality. Compared with male subjects (n = 5,241), female subjects (n = 2,165) were older and displayed greater prevalences of paroxysmal AF, heart failure, and hypertension but less prevalences of diabetes, previous cerebral infarction, and coronary artery disease. Male and female patients had mean CHADS2 (Congestive heart failure, Hypertension, Age of 75 years or more, Diabetes mellitus and prior Stroke or transient ischemic attack) scores of 1.6 and 1.8, respectively (p <0.001). Warfarin was given to 87% of male patients and 86% of female patients (p = 0.760), and the 2 genders displayed similar mean international normalized ratio of prothrombin time values at baseline (1.91 vs 1.90, respectively, p = 0.756). Multivariate logistic regression analysis indicated that male gender was an independent risk factor for major hemorrhaging (odds ratio 1.59, 95% confidence interval 1.05 to 2.40, p = 0.027) and all-cause mortality (odds ratio 1.78, 95% confidence interval 1.25 to 2.55, p <0.002) but not for thromboembolic events (odds ratio 1.24, 95% confidence interval 0.83 to 1.86, p = 0.297) or cardiovascular mortality (odds ratio 0.96, 95% confidence interval 0.56 to 1.66, p = 0.893). In conclusion, female gender is not a risk factor for thromboembolic events among Japanese patients with NVAF who were treated mostly with warfarin. However, male gender is a risk factor for major hemorrhaging and all-cause mortality.

Ablation of idiopathic ventricular fibrillation targeting short coupled ventricular premature contractions originating from a right ventricular papillary muscle

We describe a 38-year-old male who experienced several episodes of syncope after having ventricular fibrillation. The electrocardiographic monitoring after his hospitalization revealed repetitive polymorphic ventricular tachycardias. All polymorphic ventricular tachycardias were consistently initiated by a short-coupled monomorphic ventricular premature contraction (VPC). This VPC was suggested to originate from the inferoposterior region of the right ventricle (RV). Radiofrequency catheter ablation targeting the VPC was successfully performed, and the CARTO merge system (Biosense Webster Inc., Diamond Bar, CA, USA) revealed that the culprit region was the root of the posterior papillary muscle of the RV. A subsequent follow-up of 15 months has been uneventful. <Learning objective: This is a case report of idiopathic ventricular fibrillation (IVF) triggered by a ventricular premature contraction (VPC) from the posterior papillary muscle of the right ventricle. We can learn about the relationship between the anatomical structure and the possible mechanisms of the short-coupled variant of Torsade de Pointes.>.

Effects of azelnidipine on uric acid metabolism in patients with essential hypertension

PURPOSE

To examine effects of a long-acting calcium channel blocker (CCB) azelnidipine on uric acid metabolism in hypertensive patients.

METHODS

Azelnidipine was administered to 72 patients at a daily dose of 8 mg or 16 mg. In 22 cases out of the 72 patients, a different CCB was switched to azelnidipine. Blood pressure was measured and biochemical parameters of blood and urine were evaluated before and 2-3 months after the administration.

RESULTS

Azelnidipine significantly decreased both systolic and diastolic blood pressure and the heart rate. It decreased both serum urate levels and the urinary uric acid to creatinine ratio (Uur/Ucr), but did not affect the uric acid clearance to creatinine clearance ratio (Cur/Ccr). Azelnidipine decreased both Uur/Ucr and Cur/Ccr in patients with Uur/Ucr ≥ 0.5 or ≥ 0.34, although it did not change these clearance parameters in patients with Uur/Ucr <0.5 or <0.34. Azelnidipine decreased the serum urate levels and Uur/Ucr in hyperuricemic patients with uric acid levels ≥ 7.0 mg/dL in males and ≥ 6.0 mg/dL in females. It did not change these parameters in normouricemic patients with serum urate levels <7.0 mg/dL in males and <6.0 mg/dL in females. Azelnidipine decreased Uur/Ucr and Cur/Ccr in hyperuricemic patients with normal or over excretion of uric acid, although it did not change these clearance parameters in hyperuricemic patients with uric acid hypoexcretion.

CONCLUSIONS

Azelnidipine decreased the serum urate acid levels and Uur/Ucr, and this response was most prominent in hyperuricemic patients or patients with normal and over excretion of uric acid.

Effect of carvedilol on reduction in heart rate in patients with chronic atrial fibrillation

Background

Currently, β-blockers are used most frequently for the purpose of heart rate (HR) control in patients with atrial fibrillation (AF) in worldwide. Carvedilol is one of common β-blockers and known to be effective for hypertension and heart failure. However, little can be found the information about the HR-lowering effect of carvedilol in patients with AF without heart failure. Therefore, we conducted this study to investigate the effect of carvedilol on HR in 3-minute electrocardiogram (ECG) and total heart beats (THBs) in 24-hour Holter ECG monitoring in patients with persistent or permanent AF.

Methods

A total of 13 hypertensive patients (73 ± 12 years, 7 males) with AF and HR 90 bpm or more were enrolled. All patients received carvedilol from 5 mg/day. The dose of drug was titrated every 4 weeks and raised to 10 or 20 mg/day if HR was 80 bpm or more.

Results

Mean HR was decreased from 101.9 ± 13.9 to 85.2 ± 15.2 bpm (P < 0.05) after treatment with carvedilol. THBs were also significantly decreased from 128 to 115 × 1,000/day (P < 0.001). Percent reduction in HR and THBs were 13.9% and 10.7%, respectively. The scores of Atrial Fibrillation Quality of Life Questionnaire (AFQLQ) did not change. Only one patient was required to discontinue carvedilol due to congestive heart failure.

Conclusions

We observed that carvedilol certainly reduced HR in patients with chronic AF. We believe that the effect of carvedilol on the reduction in HR can contribute to the management of AF patients treated with rate-control strategy.

Histopathological verification for successful ablation of mitral isthmus ventricular tachycardia complicated with cardiac sarcoidosis

A 68-year-old man died a few days after catheter ablation of drug-resistant, monomorphic ventricular tachycardia (VT) complicated with cardiac sarcoidosis. The diagnosis of mitral isthmus VT was made from electrophysiological observations, including electro-anatomical activation and voltage map, pace-mapping, entrainment mapping and ablation outcome. On autopsy of the heart, sarcoidic lesion with scattered fibrous tissue in the mitral isthmus was non-transmural, and the surviving myocardium serving as the reentry circuit in the endomyocardium was isolated from the adjacent viable epimyocardium, enabling the sustenance of macroreentry across the mitral isthmus. Non-transmural lesions produced by RF delivery created a barrier sufficient to interrupt the myocardial bundles located in the mitral isthmus, eliminating the mitral isthmus VT.

Respiratory cycle-dependent atrial tachycardia: prevalence, electrocardiographic and electrophysiologic characteristics, and outcome after catheter ablation

BACKGROUND

Little is known about the tachyarrhythmias relating to respiration. Case reports presented patients with respiratory cycle-dependent atrial tachycardias (RCATs), which cyclically emerge after starting inspiration and cease during expiration.

OBJECTIVE

The aim of the present study was to elucidate the prevalence, characteristics, and long-term outcome after radiofrequency catheter ablation (RFCA) of RCATs.

METHODS

The electrocardiographic and electrophysiologic properties and results of RFCA were analyzed in 60 patients with a total of 71 focal atrial tachycardias (ATs).

RESULTS

Nine RCATs (13%) were observed in 7 patients (12%). RCATs were irregular, with a mean cycle length ranging from 220 to 650 ms, and developed incessantly accounting for 32% ± 14% of the 24-hour heartbeats. The P-wave morphology was positive or biphasic (positive to negative) in V1, and positive in I and II. The electroanatomical mapping demonstrated a centrifugal activation pattern, with the earliest site located at the antrum of the right superior pulmonary vein (RSPV), inside the RSPV, and inside the superior vena cava (SVC) in 4, 2, and 3 RCATs, respectively. Radiofrequency energy delivery at the earliest site or the electrical isolation of the RSPV and SVC suppressed all RCATs. During a follow-up of 25 ± 15 months, 1 RCAT recurred and was eliminated in a second procedure.

CONCLUSION

RCATs were observed in 13% of the focal ATs. As presumed from the P-wave morphologies, their foci converged around the RSPV or inside the SVC. RFCA was effective to eliminate RCATs.

Reciprocal control of hERG stability by Hsp70 and Hsc70 with implication for restoration of LQT2 mutant stability

RATIONALE

The human ether-a-go-go-related gene (hERG) encodes the α subunit of the potassium current I(Kr). It is highly expressed in cardiomyocytes and its mutations cause long QT syndrome type 2. Heat shock protein (Hsp)70 is known to promote maturation of hERG. Hsp70 and heat shock cognate (Hsc70) 70 has been suggested to play a similar function. However, Hsc70 has recently been reported to counteract Hsp70.

OBJECTIVE

We investigated whether Hsc70 counteracts Hsp70 in the control of wild-type and mutant hERG stability.

METHODS AND RESULTS

Coexpression of Hsp70 with hERG in HEK293 cells suppressed hERG ubiquitination and increased the levels of both immature and mature forms of hERG. Immunocytochemistry revealed increased levels of hERG in the endoplasmic reticulum and on the cell surface. Electrophysiological studies showed increased I(Kr). All these effects of Hsp70 were abolished by Hsc70 coexpression. Heat shock treatment of HL-1 mouse cardiomyocytes induced endogenous Hsp70, switched mouse ERG associated with Hsc70 to Hsp70, increased I(Kr), and shortened action potential duration. Channels with disease-causing missense mutations in intracellular domains had a higher binding capacity to Hsc70 than wild-type channels and channels with mutations in the pore region. Knockdown of Hsc70 by small interfering RNA or heat shock prevented degradation of mutant hERG proteins with mutations in intracellular domains.

CONCLUSIONS

These results indicate reciprocal control of hERG stability by Hsp70 and Hsc70. Hsc70 is a potential target in the treatment of LQT2 resulting from missense hERG mutations.

Effect of losartan and benzbromarone on the level of human urate transporter 1 mRNA

Both an angiotensin II receptor blocker, losartan (CAS 124750-99-8) and a serum urate lowering agent, benzbromarone (CAS 3562-84-3) exert a uricosuric action by inhibiting urate transporter 1 (URAT1). A recent clinical trial indicated that losartan could reduce the level of serum urate in hypertensive patients treated with urate lowering agents, suggesting the different mode of action of losartan from benzbromarone. In the present study, the effect of losartan and benzbromarone on the level of URAT1 mRNA was determined in transfected HEK293 cells. Losartan caused a significant reduction of its mRNA level, whereas it was not affected by benzbromarone. These results indicate that losartan decreases the level of human URAT1 mRNA, which may underlie the uricosuric action of losartan in hypertensive patients treated with serum urate lowering agents.

[Calcium antagonists: current and future applications based on new evidence. The mechanisms on lowering serum uric acid level by calcium channel blockers]

In hypertensive subjects, their serum uric acid levels tend to be higher because of decreasing urinary secretion or overproduction of uric acid. Among calcium channel blockers (CCBs) , long acting nifedipine and cilnidipine reveal serum uric acid lowering action. They decrease the production of uric acid precursor in skeletal muscles under anaerobic condition induced by hypertension or insulin resistance. Hyperuricemia is considered to be a risk factor of not only gout but also renal and cardiovascular diseases, thus, it is important to use CCBs without adverse effect on uric acid metabolisms.

Uric acid-lowering treatment with benzbromarone in patients with heart failure: a double-blind placebo-controlled crossover preliminary study

BACKGROUND

Hyperuricemia is common in chronic heart failure (CHF), and it is a strong independent marker of prognosis. Upregulated xanthine oxidase (XO) activity and impaired renal excretion have been shown to account for increased serum uric acid (UA) levels in CHF. Therapeutic interventions with allopurinol to reduce UA levels by XO inhibition have been shown to be beneficial. Discussions are ongoing whether UA itself is actively involved or it is a mere marker of upregulated XO activity within CHF pathophysiology. Therefore, the aim of this study was to test the effect of lowering UA by uricosuric treatment without XO inhibition on hemodynamic and metabolic characteristics of CHF. Impaired renal excretion of UA was taken into account.

METHODS AND RESULTS

Serum UA (SUA), urinary UA (uUA) excretion, and renal clearance test for UA (Cl(UA)) were measured in 82 patients with CHF. SUA was significantly increased compared with controls of similar age (control, 5.45+/-0.70 mg/dL; New York Heart Association I, 6.48+/-1.70 mg/dL; New York Heart Association II, 7.34+/-1.94 mg/dL; New York Heart Association III, 7.61+/-2.11 mg/dL; P<0.01). Patients with CHF showed lower uUA excretion and Cl(UA). On multivariate analysis, insulin, brain natriuretic peptide (P<0.01), and creatinine levels (P=0.05) showed independent correlation with SUA. The treatment effect of the uricosuric agent benzbromarone was tested in 14 patients with CHF with hyperuricemia in a double-blind, placebo-controlled, randomized crossover study design. Benzbromarone significantly decreased SUA (P<0.01). Brain natriuretic peptide, left ventricular ejection fraction, and dimensions in echocardiographic assessment did not change after benzbromarone therapy. In contrast, fasting insulin (placebo, 18.8+/-8.9 microU/mL; benzbromarone, 11.0+/-6.2 microU/mL; P<0.05), homeostasis model assessment of insulin resistance index (placebo, 5.4+/-2.6; benzbromarone, 3.0+/-1.7; P<0.05), and tumor necrosis factor-alpha (placebo, 2.59+/-0.63 pg/mL; benzbromarone, 2.14+/-0.51 pg/mL; P<0.05) improved after benzbromarone, and the changes in tumor necrosis factor-alpha levels were correlated with reduction of SUA (P<0.05).

CONCLUSIONS

These results show that UA lowering without XO inhibition may not have an effect on hemodynamic impairment in CHF pathophysiology. To the extent that these data are correct, this finding suggests that upregulated XO activity rather than UA itself is actively involved in hemodynamic impairment in CHF. Clinical Trial Registration- clinical trials.gov. Identifier: NCT00422318.

Identification, isolation and characterization of HCN4-positive pacemaking cells derived from murine embryonic stem cells during cardiac differentiation

BACKGROUND

Development of biological pacemaker is a potential treatment for bradyarrhythmias. Pacemaker cells could be extracted from differentiated embryonic stem (ES) cells based on their specific cell marker hyperpolarization-activated cyclic nucleotide-gated (HCN)4. The goal of this study was to develop a method of identification, isolation, and characterization of pacemaking cells derived from differentiated ES cells with GFP driven by HCN4 promoter.

METHODS AND RESULTS

Polymerase chain reaction (PCR) screening and southern blot analysis revealed that HCN4p-EGFP trans-gene was stably integrated into the chromosome of mouse AB1 ES cells. RT-PCR and immunostaining results showed similar expression of the specific cardiac pacemaker markers of the HCN4p-EGFP ES cells and its parental AB1 ES cell lines. Although HCN4p-EGFP trans-gene may have slight effect on the general mesodermal differentiation, it had no effect on the pluripotency of ES cells, on the transcription of cardiac specific factors and cardiac contractile proteins, and on the capability of ES cells to differentiate into pacemaker cells. Electrophysiological study indicated that HCN4p-GFP-positive cells revealed the spontaneous action potential, which was slowed by the treatment with 2 mM Cs(+), and expressed the hyperpolarization-activeted cation current I(f) encoded by HCN4 gene.

CONCLUSION

By the approach of using stable transfectant of HCN4p-EGFP gene, the identification, isolation, and characterization of ES cell-derived pacemaking cells could be carried out.

Appropriate use of nasal continuous positive airway pressure decreases elevated C-reactive protein in patients with obstructive sleep apnea

BACKGROUND

C-reactive protein (CRP) is an important risk factor for cardiovascular disease. Furthermore, it has been reported that levels of CRP are increased in patients with obstructive sleep apnea (OSA). The aim of this study was to examine the effects of long-term therapy with nasal continuous positive airway pressure (nCPAP) on CRP levels and to investigate whether compliance with nCPAP therapy more effectively attenuated markers of systemic inflammation in patients with OSA.

METHODS AND RESULTS

Fifty-five patients (mean [+/- SEM] age, 55 +/- 2 years; 44 male patients, 11 female patients) with newly diagnosed moderate-to-severe OSA (apnea-hypopnea index > 20 events/h) were studied before and after 6 months of nCPAP treatment. There was a significant reduction in CRP levels after nCPAP therapy (before nCPAP therapy, 0.23 +/- 0.03 mg/dL; after nCPAP therapy, 0.17 +/- 0.02 mg/dL; p < 0.01). Additionally, we divided these patients into two groups based on adherence to nCPAP therapy. A group of patients using nCPAP > 4 h/d and > 5 d/wk were designated as the good compliance group. The decrease in CRP concentration was significant (before nCPAP therapy, 0.23 +/- 0.04 mg/dL; after nCPAP therapy, 0.16 +/- 0.03 mg/dL; p < 0.05) in the good compliance group but not in the poor compliance group (before nCPAP therapy, 0.24 +/- 0.05 mg/dL; after nCPAP therapy, 0.20 +/- 0.05 mg/dL; p = 0.21). Furthermore, we divided those patients into a high CRP group (>/= 0.2 mg/dL) and a normal CRP group (< 0.2 mg/dL) before nCPAP therapy. The significant decrease in CRP levels in the good compliance group was evident only in those patients with an initially elevated CRP level (before nCPAP therapy, 0.48 +/- 0.08 mg/dL; after nCPAP therapy, 0.29 +/- 0.06 mg/dL; p < 0.05).

CONCLUSION

Appropriate use of nCPAP in patients with OSA may be required to decrease elevated CRP levels, with possible implications for cardiovascular morbidity and mortality.

Pendrin is a novel autoantigen recognized by patients with autoimmune thyroid diseases

CONTEXT

Pendrin is an apical protein of thyroid follicular cells, responsible for the efflux of iodide into the follicular lumen via an iodide-chloride transport mechanism. It is unknown whether pendrin is recognized by autoantibodies.

OBJECTIVE

Our objective was to examine the prevalence of pendrin antibodies in autoimmune thyroid diseases and compare with that of thyroglobulin, thyroperoxidase, TSH receptor, and sodium iodide symporter antibodies.

DESIGN

In a prevalent case-control study, we analyzed the sera of 140 autoimmune thyroid disease cases (100 with Graves' disease and 40 with Hashimoto's thyroiditis) and 80 controls (50 healthy subjects, 10 patients with papillary thyroid cancer, 10 with systemic lupus erythematosus, and 10 with rheumatoid arthritis). Pendrin antibodies were measured by immunoblotting using extract of COS-7 cells transfected with pendrin and a rabbit polyclonal pendrin antibody.

RESULTS

Pendrin antibodies were found in 81% of the cases and 9% of controls (odds ratio = 44; P < 0.0001). Among cases, pendrin antibodies were more frequent and of higher titers in Hashimoto's thyroiditis than in Graves' disease. Pendrin antibodies correlated significantly with thyroglobulin, thyroperoxidase, and sodium iodide symporter antibodies but not with TSH receptor antibodies. Pendrin antibodies were equally effective as thyroglobulin and thyroperoxidase antibodies in diagnosis of autoimmune thyroid diseases, especially Hashimoto's thyroiditis.

CONCLUSIONS

The study identifies pendrin as a novel autoantigen recognized by patients with autoimmune thyroid diseases and proposes the use of pendrin antibodies as an accurate diagnostic tool.

Ubiquitin-proteasome system impairment caused by a missense cardiac myosin-binding protein C mutation and associated with cardiac dysfunction in hypertrophic cardiomyopathy

The ubiquitin-proteasome system is responsible for the disappearance of truncated cardiac myosin-binding protein C, and the suppression of its activity contributes to cardiac dysfunction. This study investigated whether missense cardiac myosin-binding protein C gene (MYBPC3) mutation in hypertrophic cardiomyopathy (HCM) leads to destabilization of its protein, causes UPS impairment, and is associated with cardiac dysfunction. Mutations were identified in Japanese HCM patients using denaturing HPLC and sequencing. Heterologous expression was investigated in COS-7 cells as well as neonatal rat cardiac myocytes to examine protein stability and proteasome activity. The cardiac function was measured using echocardiography. Five novel MYBPC3 mutations -- E344K, DeltaK814, Delta2864-2865GC, Q998E, and T1046M -- were identified in this study. Compared with the wild type and other mutations, the E334K protein level was significantly lower, it was degraded faster, it had a higher level of polyubiquination, and increased in cells pretreated with the proteasome inhibitor MG132 (50 microM, 6 h). The electrical charge of its amino acid at position 334 influenced its stability, but E334K did not affect its phosphorylation. The E334K protein reduced cellular 20 S proteasome activity, increased the proapoptotic/antiapoptotic protein ratio, and enhanced apoptosis in transfected Cos-7 cells and neonatal rat cardiac myocytes. Patients carrying the E334K mutation presented significant left ventricular dysfunction and dilation. The conclusion is the missense MYBPC3 mutation E334K destabilizes its protein through UPS and may contribute to cardiac dysfunction in HCM through impairment of the ubiquitin-proteasome system.

Uricosuric action of losartan via the inhibition of urate transporter 1 (URAT 1) in hypertensive patients

BACKGROUND

The angiotensin receptor blocker losartan inhibited urate transporter 1 (URAT1) according to in vitro experiments. However, it is still unknown whether the inhibitory effect of losartan on URAT1 contributes to its uricosuric action in humans.

METHODS

Thirty-two patients with hypertension and nine patients with idiopathic renal hypouricemia (five with and four without hypertension) were enrolled for this study. Hypertensive patients were prescribed oral losartan (50 mg/day, n = 16) or candesartan (8 mg/day, n = 16). Before and after 1-month treatment, the serum concentration of urate (Sur) and creatinine (Scr), and the clearance value of urate (Cur) and creatinine (Ccr) were determined. Clearance studies using the URAT1 inhibitor benzbromarone (100 mg/day) or losartan (50 mg/day) loading test were also performed in these patients.

RESULTS

Blood pressure (BP) significantly decreased in the patients treated with either losartan or candesartan. Losartan significantly reduced Sur, which was associated with a concomitant increase in the Cur/Ccr ratio, whereas candesartan did not alter these parameters. In hypertensive patients with loss-of-function mutation of URAT1, losartan did not alter either Sur or Cur/Ccr, nor did benzbromarone. The lack of effect of URAT1 inhibitors on renal excretion of urate was independent of the renal function of hypouricemic patients. On the other hand, both losartan and benzbromarone increased Cur/Ccr ratio in hypertensive patients harboring the wild URAT1 gene, regardless of the presence of hypouricemia.

CONCLUSIONS

These findings suggested that losartan inhibited URAT1 and thereby it lowered Sur levels in hypertensive patients.

[Idiopathic hyperuricemia with overproduction of uric acid]

Idiopathic hyperuricemia is generally defined as hyperuricemia caused by unknown origin. Idiopathic hyperuricemia is categorized as overproducing or underexcretion of uric acid. Overproduced uric acid is caused by increased biosynthesis of purine bodies, hypermetabolization of purine bodies, or increased intake of dietary purine bodies. Idiopathic hyperuricemia with overproducing uric acid can be diagnosed by amount of excreted uric acid in the urine. Recently it has been identified that hypertension are frequently associated with myogenic hyperuricemia converted from overproduced hypoxanthine in the skeletal muscles. Some anti-hypertensive drugs including alpha1 blocker, ACE inhibitor, alphabeta blocker, or long-acting Ca blocker attenuated the myogenic hyperuricemia. Thus, these drugs may be helpful in the management of hypertension with hyperuricemia.

[How do we set the standard value of serum uric acid levels?]

In most medical facilities in Japan, either uricase-catalase or uricase-peroxidase method has been adopted as a sensitive determination of serum uric acid concentration. However, the values obtained from the same patients at different time points are often variable with those methods. Accelerated generation of uric acid and impaired excretion in the kidney are promoted by several dietary factors, such as foods with higher content of sugars (fructose and xylitol), fat and purine bases, and by alcohol consumption, starvation and dehydration. In contrast, hyperglycemia and excess salt ingestion are conductive to accelerate urate excretion. Physicians should notice representative factors fluctuating serum uric acid levels as described above.

[Other antihyperuricemic agents]

It has been reported that hyperuricemia might be responsible for cardiovascular diseases as well as gout and renal injury. Hypertension and hyperlipidemia, which are also responsible for cardiovascular diseases, are often associated with hyperuricemia. Thus, the treatment of hypertension and hyperlipidemia associated with hyperuricemia is also important. Losartan, an antihypertensive agent, and fenofibrate, an antihyperlipidemic agent, are known to have uric acid lowering effects. Both agents are useful for hyperuricemia with associated with hypertension and hyperlipidemia. In this section, we reported the characteristics and usefulness of these two agents in hyperuricemic patients with hypertension and hyperlipidemia.