Cardiac Conduction Disorders as Markers of Cardiac Events in Myotonic Dystrophy Type 1.

Background Myotonic dystrophy type 1 involves cardiac conduction disorders. Cardiac conduction disease can cause fatal arrhythmias or sudden death in patients with myotonic dystrophy type 1. Methods and Results This study enrolled 506 patients with myotonic dystrophy type 1 (aged ≥15 years; >50 cytosine-thymine-guanine repeats) and was treated in 9 Japanese hospitals for neuromuscular diseases from January 2006 to August 2016. We investigated genetic and clinical backgrounds including health care, activities of daily living, dietary intake, cardiac involvement, and respiratory involvement during follow-up. The cause of death or the occurrence of composite cardiac events (ie, ventricular arrhythmias, advanced atrioventricular blocks, and device implantations) were evaluated as significant outcomes. During a median follow-up period of 87 months (Q1-Q3, 37-138 months), 71 patients expired. In the univariate analysis, pacemaker implantations (hazard ratio [HR], 4.35; 95% CI, 1.22-15.50) were associated with sudden death. In contrast, PQ interval ≥240 ms, QRS duration ≥120 ms, nutrition, or respiratory failure were not associated with the incidence of sudden death. The multivariable analysis revealed that a PQ interval ≥240 ms (HR, 2.79; 95% CI, 1.9-7.19, P<0.05) or QRS duration ≥120 ms (HR, 9.41; 95% CI, 2.62-33.77, P < 0.01) were independent factors associated with a higher occurrence of cardiac events than those observed with a PQ interval <240 ms or QRS duration <120 ms; these cardiac conduction parameters were not related to sudden death. Conclusions Cardiac conduction disorders are independent markers associated with cardiac events. Further investigation on the prediction of occurrence of sudden death is warranted

Splicing misregulation of SCN5A contributes to cardiac-conduction delay and heart arrhythmia in myotonic dystrophy

Myotonic dystrophy (DM) is caused by the expression of mutant RNAs containing expanded CUG repeats that sequester muscleblind-like (MBNL) proteins, leading to alternative splicing changes. Cardiac alterations, characterized by conduction delays and arrhythmia, are the second most common cause of death in DM. Using RNA sequencing, here we identify novel splicing alterations in DM heart samples, including a switch from adult exon 6B towards fetal exon 6A in the cardiac sodium channel, SCN5A. We find that MBNL1 regulates alternative splicing of SCN5A mRNA and that the splicing variant of SCN5A produced in DM presents a reduced excitability compared with the control adult isoform. Importantly, reproducing splicing alteration of Scn5a in mice is sufficient to promote heart arrhythmia and cardiac-conduction delay, two predominant features of myotonic dystrophy. In conclusion, misregulation of the alternative splicing of SCN5A may contribute to a subset of the cardiac dysfunctions observed in myotonic dystrophy.Peer reviewe

Pulmonary Inflammation of Well-Dispersed Multi-Wall Carbon Nanotubes Following Intratracheal Instillation: Toxicity by Fiber of 1–5 µm in Length

The pulmonary toxicity of multi-wall carbon nanotubes (MWCNT) were examined by intratracheal instillation. We prepared a well-dispersed MWCNT dispersion including MWCNTs of 3.71 µm geometric average length. The fiber length of most of the MWCNTs in the dispersion was 10 µm or less. The MWCNT dispersion was administered to rat lung by single intratracheal instillation at doses of 0.2 mg and 0.6 mg/rat. Bronchoalveolar lavage fluid (BALF) was collected at 3 days, 1 week, 1 month, 3 months, and 6 months after instillation. The influences of the longer MWCNTs on the induction of inflammation and oxidative stress were examined by the number of neutrophils, cytokine induced neutrophil chemoattractant-1 (CINC-1), CINC-2, CINC-3 and HO-1 in the BALF. Additionally, ho-1 gene expression in the lung was examined. The intratracheal instillation of MWCNT induced transient inflammation dose dependently in the lung. The number of neutrophils was highest at 3 days after instillation and then decreased. However, the neutrophils in the MWCNT administered animals tended to be higher than in the control group until 3 months after instillation. The CINC-1 and CINC-2 concentrations in the BALF increased at 1 month after instillation. There were no significant differences in CINC-3 and HO-1 between the MWCNT administered animals and the control animals. These results revealed that the MWCNTs of 1–10 µm in length induced persistent inflammation in rat lung. There were no remarkable differences between the MWCNTs in the present study and previously reported, shorter MWCNTs prepared from “the same” raw MWCNT material

Comparison of the Pulmonary Oxidative Stress Caused by Intratracheal Instillation and Inhalation of NiO Nanoparticles when Equivalent Amounts of NiO Are Retained in the Lung

NiO nanoparticles were administered to rat lungs via intratracheal instillation or inhalation. During pulmonary toxicity caused by NiO nanoparticles, the induction of oxidative stress is a major factor. Both intratracheal instillation and inhalation of NiO nanoparticles induced pulmonary oxidative stress. The oxidative stress response protein, heme oxygenase-1 (HO-1), was induced by the administration of NiO nanoparticles at both the protein and gene expression level. Additionally, certain oxidative-stress markers in the lung, such as 8-iso-prostaglandin F2α, thioredoxin, and inducible nitric oxide synthase were increased. Furthermore, the concentration of myeloperoxidase (MPO) in the lung was also increased by the administration of NiO nanoparticles. When the amount of NiO in the lung is similar, the responses against pulmonary oxidative stress of intratracheal instillation and inhalation are also similar. However, the state of pulmonary oxidative stress in the early phase was different between intratracheal instillation and inhalation, even if the amount of NiO in the lung was similar. Inhalation causes milder oxidative stress than that caused by intratracheal instillation. On evaluation of the nanoparticle-induced pulmonary oxidative stress in the early phase, we should understand the different states of oxidative stress induced by intratracheal instillation and inhalation

Fabrication of Dicarboxylic-Acid- and Silica-Substituted Octacalcium Phosphate Blocks with Stronger Mechanical Strength

Octacalcium phosphate (OCP) is an attractive base material to combine into components developed for medical purposes, especially those used in bone replacement procedures, not only because of its excellent biocompatibility but also because of its ability to intercalate with multiple types of molecular layers such as silica, dicarboxylic acid, and various cations. On the other hand, there are no examples of simultaneous substituting for several different compounds on OCPs. Therefore, in this study, the physical and mechanical strength (DTS: diametral tensile strength) of OCPs substituted with both silica and dicarboxylic acids (thiomalate: SH-malate) were evaluated. By optimizing the amount of SH-malate, we were able to prepare a block consisting of OCPs with both silica and SH-malate supported in the interlayer. The composition of the OCP-based compound comprising this block was Ca8Na1.07H6.33(PO4)4.44(SiO4)1.32(SH-malate)2.40·nH2O. Interestingly, the low mechanical strength, a drawback of silica-substituted OCP blocks, could be improved by dicarboxylic acid substituting. The dicarboxylic acid addition increased the mechanical strength of silica-substituted OCP blocks, and the acid successfully incorporated into the interlayer, even with the presence of silica. These results are expected to advance the creation of better silica-substituted OCPs and improved bone replacement materials

Application of traditional herbal medicines to suppress the reversion of polio vaccine viruses to the neurovirulent genotype

Background　The oral poliovirus vaccine (OPV) is regarded as one of the most effective and safest vaccines. However, some paralytic cases have been reported among vaccinees and individuals who have been in contact with vaccinees, because vaccine viruses undergo neurovirulent reversion during repeated replication in the alimentary tract. Moreover, the revertants are excreted with the feces into the environment, and the viruses have caused epidemics of poliomyelitis in the world. Objective　We have reported that Ninjin'yoeito suppressed the reversion of polio vaccine viruses. In this study, to clarify the herbal constituent which takes part in the suppressive effect, we investigated the effect of Ninjinto, which is composed of simpler herbal constituents than Ninjin'yoeito, and of the individual herbal constituents in Ninjinto. Methods　Polio vaccine viruses were serially passaged three times in the presence of herbal medicines in cells derived from the human alimentary tract. The reversion of the passaged viruses was analyzed by the MAPREC and non-RI-modified MAPREC method, designed to estimate the ratio of revertants in a virus population. Results　It was shown that Ninjinto suppressed the reversion of polio vaccine viruses. Although Ginseng Radix and Glycyrrhizae Radix (common herbal constituents in Ninjinto and Ninjin'yoeito) did not show the suppressive effect, the mixture of both herbal constituents was a little inhibitory in regard to the reversion of the viruses. Conclusion　It is quite likely that the suppressive effect on reversion is not a simple process. A complicated interaction of some components of the herbal constituents might take part in the effect. It is expected that traditional herbal medicines like Ninjinto and Ninjin'yoeito will contribute to solving the problems of OPV though further analyses of the herbal constituents and their components are necessary to clarify the mechanism of the suppressive effect.背景　経口生ポリオワクチン(OPV) は、安全性と有効性が高いワクチンである。 しかし、その一方、極めて低い頻度ではあるが、ワクチン被接種者あるいは被接種者に接触した人に、ポリオ(急性灰白髄炎)の発症例が報告されている。これは弱毒ワクチンウイルスが、人の消化管細胞で増殖する過程において、毒力復帰変異を起こすことに起因すると考えられている。 更に、その変異ウイルスが、糞便とともに環境中に排泄されることで、ポリオの新たな流行を世界各地で引き起こし、大きな問題となっている。目的　我々は、和漢薬の一つである人参養栄湯エキスに、ポリオワクチンウイルスの毒力復帰変異に対する抑制効果が見られることを既に報告した。本研究では、人参養栄湯の中の、どのような生薬成分がこの抑制効果に関与しているかを調べるために、人参養栄湯よりも混合(構成)生薬の種類が極端に少ない人参湯エキスについて、更に、人参養栄湯と人参湯の共通構成生薬である人参と甘草の両生薬エキスについて、毒力復帰変異抑制効果の解析を行った。方法　ポリオワクチンウイルスをヒト消化管由来細胞を用いて、人参養栄湯エキス、人参湯エキス、あるいは上記2種の生薬エキスをそれぞれ至敵濃度含有する培地中で、3代継代培養を行った。これら継代ウイルスの毒力復帰変異について、遺伝子レベルでウイルスの毒力（神経毒力）の強さを測定できるMAPREC法、およびMAPREC法の一部を改変した非RI-MAPREC法で解析した。結果　人参湯エキスにも人参養栄湯エキスに近い毒力復帰変異抑制効果が認められたが、人参と甘草の両生薬エキスについては、ほとんど抑制効果は見られなかった。しかし、両生薬エキスを混合して用いることで、若干の抑制効果が認められた。結論　人参養栄湯や人参湯によるポリオワクチンウイルスの毒力復帰変異抑制効果は、単純にどれか1種類の生薬成分によって起きるものではなく、複数の成分による複雑な相互作用が関与している可能性が示唆された。どのような生薬成分が、どのようなメカニズムで毒力復帰変異の抑制を起こすのか、解析を行う必要が残されているが、人参養栄湯や人参湯のような和漢薬は、OPVがもつ問題の解決に大きく貢献することが期待される