Interpretations of SARS-CoV-2 IgM and IgG antibody titers in the seroepidemiological study of asymptomatic healthy volunteers.

Introduction: The usefulness of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibody tests in asymptomatic individuals has not been well validated, although they have satisfied sensitivity and specificity in symptomatic patients. In this study, we investigated the significance of IgM and IgG antibody titers against SARS-CoV-2 in the serum of asymptomatic healthy subjects.

Methods: From June 2020, we recruited 10,039 participants to the project named the University of Tokyo COVID-19 Antibody Titer Survey (UT-CATS), and measured iFlash-SARS-CoV-2 IgM and IgG (YHLO IgM and IgG) titers in the collected serum.

Relationship between chronotropic incompetence and β-blockers based on changes in chronotropic response during cardiopulmonary exercise testing.

Background: Chronotropic incompetence (CI), an attenuated heart rate (HR) response to exercise, is common in patients with cardiovascular disease. The aim of this study was to assess changes in the chronotropic response (CR) during cardiopulmonary exercise testing (CPET) in patients undergoing cardiac rehabilitation and investigate the effects of β-blockers.

Methods: Patients undergoing cardiac rehabilitation performed CPET.

High-frequency powers hidden within QRS complex as an additional predictor of lethal ventricular arrhythmias to ventricular late potential in post-myocardial infarction patients.

Background: Ventricular late potentials (VLPs) have been known to be a predictor of lethal ventricular arrhythmias (L-VAs); however, detection of other arrhythmogenic signals within the QRS complex remains obscure.

Objective: The aim of this study was to evaluate whether abnormal intra-QRS high-frequency powers (IQHFP) within the QRS complex become a new predictor of L-VAs in addition to VLPs.

Methods: Both 12-lead electrocardiograms (ECG) and VLPs were recorded from 142 subjects, including 37 patients without heart diseases, 97 patients post-myocardial infarction (MI), and 45 post-MI patients with L-VAs.

Morbidity prevalence rate of kawasaki disease assessed by single cross-sectional history-taking.

The need for long-term follow-up in Kawasaki disease is poorly recognized although cardiac sudden death attacks asymptomatic young people with past illness after a long latent period. Therefore, in order to prevent cardiac disasters, high risk groups should be identified and the prevalence rate of the disease should be determined for crisis management. A total of 9,965 consecutive freshmen at the University of Tokyo were the subject of a questionnaire.

Gene therapy prevents disruption of dystrophin-related proteins in a model of hereditary dilated cardiomyopathy in hamsters.

Background: The TO-2 hamster is an animal model of dilated cardiomyopathy (DCM). It has genetic and clinical features in common with humans who carry the gene deletion or mutation of the delta-sarcoglycan (SG) gene, a component in dystrophin-related proteins (DRP). DRP stabilise the sarcolemma during cardiac contraction.

Molecular and pharmacological characteristics of transient voltage-dependent K+ currents in cultured human pulmonary arterial smooth muscle cells.

The A-type voltage-dependent K(+) current (I(A)) has been identified in several types of smooth muscle cells including the pulmonary artery (PA), but little is known about the pharmacological and molecular characteristics of I(A) in human pulmonary arterial smooth muscle cells (hPASMCs). We investigated I(A) expressed in cultured PASMCs isolated from the human main pulmonary artery, using patch-clamp techniques, reverse transcriptase-polymerase chain reaction (RT-PCR), quantitative real-time RT-PCR and immunocytochemical studies. With high EGTA and ATP in the pipette, the outward currents were dominated by a transient K(+) current (I(A)), followed by a relatively small sustained outward current (I(K)).

Acute and chronic effects of eicosapentaenoic acid on voltage-gated sodium channel expressed in cultured human bronchial smooth muscle cells.

This study investigated acute and chronic effects of eicosapentaenoic acid (EPA) on voltage-gated Na+ current (I(Na)) expressed in cultured human bronchial smooth muscle cells (hBSMCs). The whole-cell voltage clamp technique and quantitative real-time RT-PCR analysis were applied. The alterations in the fatty acid composition of phospholipids after treatment with EPA were also examined.

[T-type calcium channel blockers].

T-type calcium channels play an important role in regulating cell function in various kinds of organs, especially in cardiovascular systems. They have been recently clarified to be involved in various pathophysiological conditions, and clinically used for treatment of a variety of diseases. This review reports the usefulness and safety of the T-type calcium channel blockers.

Amlodipine increases nitric oxide production in exhaled air during exercise in patients with essential hypertension.

Background: Endothelial production of nitric oxide (NO) is attenuated in patients with essential hypertension. We investigated whether treatment with amlodipine increased exhaled NO output (VNO) at rest and during exercise in patients with essential hypertension.

Methods: We studied the effect of amlodipine in seven untreated hypertensive patients.

Voltage-gated sodium channel expressed in cultured human smooth muscle cells: involvement of SCN9A.

Voltage-gated Na(+) channel (I(Na)) is expressed under culture conditions in human smooth muscle cells (hSMCs) such as coronary myocytes. The aim of this study is to clarify the physiological, pharmacological and molecular characteristics of I(Na) expressed in cultured hSMCs obtained from bronchus, main pulmonary and coronary artery. I(Na), was recorded in these hSMCs and inhibited by tetrodotoxin (TTX) with an IC(50) value of approximately 10 nM.

Translocation and cleavage of myocardial dystrophin as a common pathway to advanced heart failure: a scheme for the progression of cardiac dysfunction.

Advanced heart failure (HF) is the leading cause of death in developed countries. The mechanism underlying the progression of cardiac dysfunction needs to be clarified to establish approaches to prevention or treatment. Here, using TO-2 hamsters with hereditary dilated cardiomyopathy, we show age-dependent cleavage and translocation of myocardial dystrophin (Dys) from the sarcolemma (SL) to the myoplasm, increased SL permeability in situ, and a close relationship between the loss of Dys and hemodynamic indices.

Inhibitory effects of carvedilol on calcium channels in vascular smooth muscle cells.

Carvedilol has hypotensive effects and inhibits agonist-induced cell proliferation of vascular smooth muscle and then prevents vascular remodeling. However, the basic mechanisms have not been clarified. We examined the effects of carvedilol on [Ca2+]i mobilization and voltage-dependent L-type Ca2+ current (ICa.

Sarcolemmal fragility secondary to the degradation of dystrophin in dilated cardiomyopathy, as estimated by electron microscopy.

A common gene deletion or mutation of delta-sarcoglycan (delta-SG) in dystrophin-related proteins (DRPs) is identified in both TO-2 strain hamsters and human families with dilated cardiomyopathy. We have succeeded in the long-lasting in vivo supplementation of a normal delta-SG gene by recombinant adeno-associated virus vector, restoration of the morphological and functional degeneration, and improvement in the prognosis of the TO-2 hamster. To evaluate the integrity of the sarcolemma (SL) and the subsequent change of organelles in cardiomyocytes of the TO-2 strain hamster, we examined electron microscopy (EM) images focusing on the sarcolemmal stability at the end stage of heart failure.

Inhibitory effects of ursodeoxycholic acid on the induction of nitric oxide synthase in vascular smooth muscle cells.

The expression of inducible nitric oxide synthase (iNOS) and the resultant increased nitric oxide production are associated with endotoxemia and atherosclerotic lesions observed in transplant hearts or balloon-injured artery. Ursodeoxycholic acid has been shown to have cardiovascular protective effects, such as inhibition of the development of transplant arteriosclerosis, but its mechanism remains unclear. Here, we investigated the effects of ursodeoxycholic acid on nitric oxide production and the expression of iNOS in vascular smooth muscle cells isolated from adult rat aorta and rabbit coronary artery.

Nonselective cation currents regulate membrane potential of rabbit coronary arterial cell: modulation by lysophosphatidylcholine.

Background: The effects of lysophosphatidylcholine (LPC) on electrophysiological activities and intracellular Ca2+ concentration ([Ca2+]i) were investigated in coronary arterial smooth muscle cells (CASMCs).

Methods And Results: The patch clamp techniques and Ca2+ measurements were applied to cultured rabbit CASMCs. The membrane potential was -46.

Cell density and growth-dependent down-regulation of both intracellular calcium responses to agonist stimuli and expression of smooth-surfaced endoplasmic reticulum in MC3T3-E1 osteoblast-like cells.

A two-dimensional intracellular Ca(2+) ([Ca(2+)](i)) imaging system was used to examine the relationship between [Ca(2+)](i) handling and the proliferation of MC3T3-E1 osteoblast-like cells. The resting [Ca(2+)](i) level in densely cultured cells was 1.5 times higher than the [Ca(2+)](i) level in sparsely cultured cells or in other cell types (mouse fibroblasts, rat vascular smooth muscle cells, and bovine endothelial cells).

Inward rectifier K(+) current in human bronchial smooth muscle cells: inhibition with antisense oligonucleotides targeted to Kir2.1 mRNA.

Inward rectifier K(+) (Kir) channels play an important role in forming membrane potential and then modulating muscle tone in certain types of smooth muscles. In cultured human bronchial smooth muscle cells (hBSMCs), Kir current was identified using whole-cell voltage clamp techniques and explored by using RT-PCR analysis of mRNA, Western blotting, and antisense oligonucleotide methods to block the synthesis of Kir channel protein. The K(+) current with strong inward rectification and high K(+) ion selectivity was observed.