Fibril Growth Behavior of Amyloid beta on Polymer-Based Planar Membranes: Implications for the Entanglement and Hydration of Polymers

The design of biosensors and artificial organs using biocompatible materials with a low affinity for amyloid beta peptide (A beta) would contribute to the inhibition of fibril growth causing Alzheimer's disease. We systematically studied the amyloidogenicity of A beta on various planar membranes. The planar membranes were prepared using biocompatible polymers, viz., poly(methyl methacrylate) (PMMA), polysulfone (PSf), poly(L-lactic acid) (PLLA), and polyvinylpyrrolidone (PVP). Phospholipids from biomembranes, viz., 1,2-dioleoyl-phosphatidylcholine (DOPC), 1,2-dipalmitoyl-phosphatidylcholine (DPPC), and polyethylene glycol-graft-phosphatidyl ethanolamine (PEG-PE) were used as controls. Phospholipid- and polymer-based membranes were prepared to determine the kinetics of A beta fibril formation. Rates of A beta nucleation on the PSf- and DPPC-based membranes were significantly higher than those on the other membranes. A beta accumulation, calculated by the change in frequency of a quartz crystal microbalance (QCM), followed the order: PSf > PLLA > DOPC > PMMA, PVP, DPPC, and PEG-PE. Nucleation rates exhibited a positive correlation with the corresponding accumulation (except for the DPPC-based membrane) and a negative correlation with the molecular weight of the polymers. Strong hydration along the polymer backbone and polymer-A beta entanglement might contribute to the accumulation of A beta and subsequent fibrillation

がん患者を支援する訪問看護師の困難感

This study aimed to identify difficulties of visiting nurses who provide assistance to home-based cancer patients requiring palliative care. In survey１, a questionnaire survey was conducted involving３０visiting nurses working for visiting nursing stations（valid response rate :９０％）, and the data were analyzed using descriptive statistics. In survey ２, a semi-structured interview based on an interview guide was conducted involving４visiting nurses working for visiting nursing stations, and the data were analyzed using a qualitative and inductive approach. The results of survey１showed that the visiting nurses were more likely to experience difficulties with the worsening of a patient’s health status and at the initiation of home-based care. They also experienced difficulties with understanding medical conditions of patients and their families, supporting decision-making, and cooperating with visiting physicians. Their level of understanding about the explanation given by physicians and the sense of value of patients and families were factors that affected such difficulties, and so, in order to resolve them, the importance of cooperating to secure medical and nursing personnel and creating a setting where they can share their knowledge of patients’ conditions and treatments was indicated. In survey ２, the following ６ categories were extracted as difficulties encountered by visiting nurses providing assistance to home-based cancer patients requiring palliative care :［dealing with the worsening of the disease］, ［predicting the end of life］, ［being unable to care for patients without cooperation］,［being involved with patients by understanding their life before illness］,［preparing a home care environment for a patient’s end-of-life］, and［limits of current work situations］. The findings suggest the need not only to provide palliative care knowledge for the prediction and understanding of illness, but also to establish a system that allows multiple medical providers to assess patients’ conditions, in order to deal with their difficulties

CORRELATION BETWEEN THROWING MOTION AND MAXIMUM ELBOW VARUS TORQUE IN FEMALE PROFESSIONAL BASEBALL PITCHERS

The purpose of this study was to identify the correlation between throwing motion and maximum elbow varus torque (MEV) in female professional baseball pitchers. Twelve pitchers without pre-existing pain were recruited. Ball velocity and pitching motion were measured. Ball velocity and, kinematic and kinetic data from each joint during the pitch were extracted to evaluate the correlation with MEV. There was no correlation between the fastest ball velocity and MEV. Sixteen kinematic and kinetic parameters were found to have significant correlations with MEV. Particularly, as trunk rotation angle to the non-throwing direction before lead foot contact (FC) increased, the MEV decreased. Rotating the trunk in the non-throwing direction before FC and immediately in the throwing direction after FC could be a key component of the throwing motion

ERRγ agonist under mechanical stretching manifests hypertrophic cardiomyopathy phenotypes of engineered cardiac tissue through maturation

iPS細胞から成熟した人工心筋組織の作製方法の開発 肥大型心筋症の治療法開発への利用に期待. 京都大学プレスリリース. 2023-10-06.Stretching and stimulating engineered heart tissues to accurately portray hypertrophic cardiomyopathy. 京都大学プレスリリース. 2023-10-17.Engineered cardiac tissue (ECT) using human induced pluripotent stem cell-derived cardiomyocytes is a promising tool for modeling heart disease. However, tissue immaturity makes robust disease modeling difficult. Here, we established a method for modeling hypertrophic cardiomyopathy (HCM) malignant (MYH7 R719Q) and nonmalignant (MYBPC3 G115∗) pathogenic sarcomere gene mutations by accelerating ECT maturation using an ERRγ agonist, T112, and mechanical stretching. ECTs treated with T112 under 10% elongation stimulation exhibited more organized and mature characteristics. Whereas matured ECTs with the MYH7 R719Q mutation showed broad HCM phenotypes, including hypertrophy, hypercontraction, diastolic dysfunction, myofibril misalignment, fibrotic change, and glycolytic activation, matured MYBPC3 G115∗ ECTs displayed limited phenotypes, which were primarily observed only under our new maturation protocol (i.e., hypertrophy). Altogether, ERRγ activation combined with mechanical stimulation enhanced ECT maturation, leading to a more accurate manifestation of HCM phenotypes, including non-cardiomyocyte activation, consistent with clinical observations

Elucidation of the liver pathophysiology of COVID-19 patients using liver-on-a-chips

新型コロナウイルス感染症（COVID-19）研究のための肝臓チップの開発 --肝障害の病態解明と治療薬の評価--. 京都大学プレスリリース. 2023-03-08.Using organ-on-a-chip technology to elucidate the liver pathophysiology of COVID-19 patients. 京都大学プレスリリース. 2023-03-08.SARS-CoV-2 induces severe organ damage not only in the lung but also in the liver, heart, kidney, and intestine. It is known that COVID-19 severity correlates with liver dysfunction, but few studies have investigated the liver pathophysiology in COVID-19 patients. Here, we elucidated liver pathophysiology in COVID-19 patients using organs-on-a-chip technology and clinical analyses. First, we developed liver-on-a-chip (LoC) which recapitulating hepatic functions around the intrahepatic bile duct and blood vessel. We found that hepatic dysfunctions, but not hepatobiliary diseases, were strongly induced by SARS-CoV-2 infection. Next, we evaluated the therapeutic effects of COVID-19 drugs to inhibit viral replication and recover hepatic dysfunctions, and found that the combination of anti-viral and immunosuppressive drugs (Remdesivir and Baricitinib) is effective to treat hepatic dysfunctions caused by SARS-CoV-2 infection. Finally, we analyzed the sera obtained from COVID-19 patients, and revealed that COVID-19 patients, who were positive for serum viral RNA, are likely to become severe and develop hepatic dysfunctions, as compared with COVID-19 patients who were negative for serum viral RNA. We succeeded in modeling the liver pathophysiology of COVID-19 patients using LoC technology and clinical samples

On τ(2)\tau^{(2)}-model in Chiral Potts Model and Cyclic Representation of Quantum Group Uq(sl2)U_q(sl_2)

We identify the precise relationship between the five-parameter $\tau^{(2)}$-family in the $N$-state chiral Potts model and XXZ chains with $U_q (sl_2)$-cyclic representation. By studying the Yang-Baxter relation of the six-vertex model, we discover an one-parameter family of $L$-operators in terms of the quantum group $U_q (sl_2)$. When $N$ is odd, the $N$-state $\tau^{(2)}$-model can be regarded as the XXZ chain of $U_{\sf q} (sl_2)$ cyclic representations with ${\sf q}^N=1$. The symmetry algebra of the $\tau^{(2)}$-model is described by the quantum affine algebra $U_{\sf q} (\hat{sl}_2)$ via the canonical representation. In general for an arbitrary $N$, we show that the XXZ chain with a $U_q (sl_2)$-cyclic representation for $q^{2N}=1$ is equivalent to two copies of the same $N$-state $\tau^{(2)}$-model.Comment: Latex 11 pages; Typos corrected, Minor changes for clearer presentation, References added and updated-Journal versio

Identification of novel clostridium perfringens type E strains that carry an iota toxin plasmid with a functional enterotoxin gene

Clostridium perfringens enterotoxin (CPE) is a major virulence factor for human gastrointestinal diseases, such as food poisoning and antibiotic associated diarrhea. The CPE-encoding gene (cpe) can be chromosomal or plasmid-borne. Recent development of conventional PCR cpe-genotyping assays makes it possible to identify cpe location (chromosomal or plasmid) in type A isolates. Initial studies for developing cpe genotyping assays indicated that all cpe-positive strains isolated from sickened patients were typable by cpe-genotypes, but surveys of C. perfringens environmental strains or strains from feces of healthy people suggested that this assay might not be useful for some cpe-carrying type A isolates. In the current study, a pulsed-field gel electrophoresis Southern blot assay showed that four cpe-genotype untypable isolates carried their cpe gene on a plasmid of ~65 kb. Complete sequence analysis of the ~65 kb variant cpe-carrying plasmid revealed no intact IS elements and a disrupted cytosine methyltransferase (dcm) gene. More importantly, this plasmid contains a conjugative transfer region, a variant cpe gene and variant iota toxin genes. The toxin genes encoded by this plasmid are expressed based upon the results of RT-PCR assays. The ~65 kb plasmid is closely related to the pCPF4969 cpe plasmid of type A isolates. MLST analyses indicated these isolates belong to a unique cluster of C. perfringens. Overall, these isolates carrying a variant functional cpe gene and iota toxin genes represent unique type E strains. © 2011 Miyamoto et al

ERRγ enhances cardiac maturation with T-tubule formation in human iPSC-derived cardiomyocytes

ヒトのiPS細胞から新生児レベルまで成熟した心筋細胞を作製する. 京都大学プレスリリース. 2021-06-21.Lowering the cost of heart cell therapies. 京都大学プレスリリース. 2021-06-21.One of the earliest maturation steps in cardiomyocytes (CMs) is the sarcomere protein isoform switch between TNNI1 and TNNI3 (fetal and neonatal/adult troponin I). Here, we generate human induced pluripotent stem cells (hiPSCs) carrying a TNNI1[EmGFP] and TNNI3[mCherry] double reporter to monitor and isolate mature sub-populations during cardiac differentiation. Extensive drug screening identifies two compounds, an estrogen-related receptor gamma (ERRγ) agonist and an S-phase kinase-associated protein 2 inhibitor, that enhances cardiac maturation and a significant change to TNNI3 expression. Expression, morphological, functional, and molecular analyses indicate that hiPSC-CMs treated with the ERRγ agonist show a larger cell size, longer sarcomere length, the presence of transverse tubules, and enhanced metabolic function and contractile and electrical properties. Here, we show that ERRγ-treated hiPSC-CMs have a mature cellular property consistent with neonatal CMs and are useful for disease modeling and regenerative medicine

Genetic characterization of type A enterotoxigenic Clostridium perfringens strains

Clostridium perfringens type A, is both a ubiquitous environmental bacterium and a major cause of human gastrointestinal disease, which usually involves strains producing C. perfringens enterotoxin (CPE). The gene (cpe) encoding this toxin can be carried on the chromosome or a large plasmid. Interestingly, strains carrying cpe on the chromosome and strains carrying cpe on a plasmid often exhibit different biological characteristics, such as resistance properties against heat. In this study, we investigated the genetic properties of C. perfringens by PCR-surveying 21 housekeeping genes and genes on representative plasmids and then confirmed those results by Southern blot assay (SB) of five genes. Furthermore, sequencing analysis of eight housekeeping genes and multilocus sequence typing (MLST) analysis were also performed. Fifty-eight C. perfringens strains were examined, including isolates from: food poisoning cases, human gastrointestinal disease cases, foods in Japan or the USA, or feces of healthy humans. In the PCR survey, eight of eleven housekeeping genes amplified positive reactions in all strains tested. However, by PCR survey and SB assay, one representative virulence gene, pfoA, was not detected in any strains carrying cpe on the chromosome. Genes involved in conjugative transfer of the cpe plasmid were also absent from almost all chromosomal cpe strains. MLST showed that, regardless of their geographic origin, date of isolation, or isolation source, chromosomal cpe isolates, i) assemble into one definitive cluster ii) lack pfoA and iii) lack a plasmid related to the cpe plasmid. Similarly, independent of their origin, strains carrying a cpe plasmid also appear to be related, but are more variable than chromosomal cpe strains, possibly because of the instability of cpe-borne plasmid(s) and/or the conjugative transfer of cpe-plasmid(s) into unrelated C. perfringens strains. © 2009 Deguchi et al

SARS-CoV-2 disrupts respiratory vascular barriers by suppressing Claudin-5 expression

臓器チップ技術を用いて新型コロナウイルスが血管へ侵入するメカニズムを解明 --Claudin-5発現抑制による呼吸器の血管内皮バリア破壊--. 京都大学プレスリリース. 2022-09-22.A study using an organ-on-a-chip reveals a mechanism of SARS-CoV-2 invasion into blood vessels --Disruption of vascular endothelial barrier in respiratory organs by decreasing Claudin-5 expression--. 京都大学プレスリリース. 2022-09-27.In the initial process of coronavirus disease 2019 (COVID-19), severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infects respiratory epithelial cells and then transfers to other organs the blood vessels. It is believed that SARS-CoV-2 can pass the vascular wall by altering the endothelial barrier using an unknown mechanism. In this study, we investigated the effect of SARS-CoV-2 on the endothelial barrier using an airway-on-a-chip that mimics respiratory organs and found that SARS-CoV-2 produced from infected epithelial cells disrupts the barrier by decreasing Claudin-5 (CLDN5), a tight junction protein, and disrupting vascular endothelial cadherin–mediated adherens junctions. Consistently, the gene and protein expression levels of CLDN5 in the lungs of a patient with COVID-19 were decreased. CLDN5 overexpression or Fluvastatin treatment rescued the SARS-CoV-2–induced respiratory endothelial barrier disruption. We concluded that the down-regulation of CLDN5 expression is a pivotal mechanism for SARS-CoV-2–induced endothelial barrier disruption in respiratory organs and that inducing CLDN5 expression is a therapeutic strategy against COVID-19