Theoretical calculations for solid oxygen under high pressure

The crystal structure of solid oxygen at low temperatures and at pressures up to 7 GPa is studied by theoretical calculations. In the calculations, the adiabatic potential of the crystal is approximated by a superposition of pair-potentials between oxygen molecules calculated by an ab-initio method. The monoclinic alpha structure is stable up to 6 GPa and calculated lattice parameters agree well with experiments. The origin of a distortion and that of an anisotropic lattice compressibility of the basal plane of alpha-O2 are clearly demonstrated. In the pressure range from 6 to 7 GPa, two kinds of structures are proposed by X-ray diffraction experiments: the alpha and orthorhombic delta structures. It is found that the energy difference between these structures becomes very small in this pressure range. The relation between this trend and the incompatible results of X-ray diffraction experiments is discussed.Comment: 12 pages, 6 figure

Considerations in hiPSC-derived cartilage for articular cartilage repair

Background: A lack of cell or tissue sources hampers regenerative medicine for articular cartilage damage. Main text: We review and discuss the possible use of pluripotent stem cells as a new source for future clinical use. Human induced pluripotent stem cells (hiPSCs) have several advantages over human embryonic stem cells (hESCs). Methods for the generation of chondrocytes and cartilage from hiPSCs have been developed. To reduce the cost of this regenerative medicine, allogeneic transplantation is preferable. hiPSC-derived cartilage shows low immunogenicity like native cartilage, because the cartilage is avascular and chondrocytes are segregated by the extracellular matrix. In addition, we consider our experience with the aberrant deposition of lipofuscin or melanin on cartilage during the chondrogenic differentiation of hiPSCs. Short conclusion: Cartilage generated from allogeneic hiPSC-derived cartilage can be used to repair articular cartilage damage

Quality assessment tests for tumorigenicity of human iPS cell-derived cartilage

Takei Y., Morioka M., Yamashita A., et al. Quality assessment tests for tumorigenicity of human iPS cell-derived cartilage. Scientific Reports 10, 12794 (2020); https://doi.org/10.1038/s41598-020-69641-4.Articular cartilage damage does not heal spontaneously and causes joint dysfunction. The implantation of induced pluripotent stem cell (iPSC)-derived cartilage (iPS-Cart) is one candidate treatment to regenerate the damaged cartilage. However, concerns of tumorigenicity are associated with iPS-Cart, because the iPSC reprogramming process and long culture time for cartilage induction could increase the chance of malignancy. We evaluated the tumorigenic risks of iPS-Cart using HeLa cells as the reference. Spike tests revealed that contamination with 100 HeLa cells in 150 mg of iPS-Cart accelerated the cell growth rate. On the other hand, 150 mg of iPS-Cart without HeLa cells reached growth arrest and senescence after culture, suggesting less than 100 tumorigenic cells, assuming they behave like HeLa cells, contaminated iPS-Cart. The implantation of 10,000 or fewer HeLa cells into joint surface defects in the knee joint of nude rat did not cause tumor formation. These in vitro and in vivo studies collectively suggest that the implantation of 15 g or less iPS-Cart in the knee joint does not risk tumor formation if assuming that the tumorigenic cells in iPS-Cart are equivalent to HeLa cells and that nude rat knee joints are comparable to human knee joints in terms of tumorigenicity. However, considering the limited immunodeficiency of nude rats, the clinical amount of iPS-Cart for implantation needs to be determined cautiously

包括的凝固機能検査による急性期川崎病における止血動態の評価

Introduction: Kawasaki disease (KD) is a systemic vasculitis involving coronary arteries, sometimes resulting in aneurysms and myocardial infarction. Hyper-coagulability in the acute-phase of KD is indicated in some circumstances based on changes of individual clotting factors. Comprehensive coagulation assays, clot waveform analysis (CWA) and thrombin/plasmin generation assay (T/P-GA), have been developed to assess physiological hemostasis, but these techniques have not been applied in KD. Methods: We utilized both assays to analyze coagulation function in KD children (n = 42) prior to intravenous-immunoglobulin (IVIG) treatment (Pre), 1-week (1W) and 1-month (1M) post-IVIG. Results: In CWA, the clot time (CT) pre-treatment was prolonged, and was significantly shortened at 1W and 1M. However, the maximum coagulation velocity (|min1|) and acceleration (|min2|) were ~2-fold greater relative to controls, indicating an overall hypercoagulable tendency. These parameters were related to fibrinogen concentration, and were decreased at 1W and declined to normal at 1M. In T/P-GA, the endogenous potentials of thrombin and plasmin were greater relative to control at each of three time-points, and measurements at 1W were greater than those Pre-treatment. The ratios of TG and PG relative to control were similar, however, suggesting well-balanced dynamic coagulation and fibrinolysis. In non-responders to IVIG, the |min1| and |min2| measurements were greater than those in responders at 1W and 1M, suggesting that non-responders remained hypercoagulable after primary treatment. Conclusion: The coagulation data observed in KD were consistent with hypercoagulability, although fibrinolytic function appeared to be well-balanced. Comprehensive assays of this nature could provide valuable information on coagulation potential in KD.博士（医学）・乙第1441号・令和元年12月5日Copyright © 2018 Elsevier Ltd. All rights reserved

Construction of microbial platform for an energy-requiring bioprocess: practical 2′-deoxyribonucleoside production involving a C−C coupling reaction with high energy substrates

BACKGROUND: Reproduction and sustainability are important for future society, and bioprocesses are one technology that can be used to realize these concepts. However, there is still limited variation in bioprocesses and there are several challenges, especially in the operation of energy-requiring bioprocesses. As an example of a microbial platform for an energy-requiring bioprocess, we established a process that efficiently and enzymatically synthesizes 2′-deoxyribonucleoside from glucose, acetaldehyde, and a nucleobase. This method consists of the coupling reactions of the reversible nucleoside degradation pathway and energy generation through the yeast glycolytic pathway. RESULTS: Using E. coli that co-express deoxyriboaldolase and phosphopentomutase, a high amount of 2′-deoxyribonucleoside was produced with efficient energy transfer under phosphate-limiting reaction conditions. Keeping the nucleobase concentration low and the mixture at a low reaction temperature increased the yield of 2′-deoxyribonucleoside relative to the amount of added nucleobase, indicating that energy was efficiently generated from glucose via the yeast glycolytic pathway under these reaction conditions. Using a one-pot reaction in which small amounts of adenine, adenosine, and acetone-dried yeast were fed into the reaction, 75 mM of 2′-deoxyinosine, the deaminated product of 2′-deoxyadenosine, was produced from glucose (600 mM), acetaldehyde (250 mM), adenine (70 mM), and adenosine (20 mM) with a high yield relative to the total base moiety input (83%). Moreover, a variety of natural dNSs were further synthesized by introducing a base-exchange reaction into the process. CONCLUSION: A critical common issue in energy-requiring bioprocess is fine control of phosphate concentration. We tried to resolve this problem, and provide the convenient recipe for establishment of energy-requiring bioprocesses. It is anticipated that the commercial demand for dNSs, which are primary metabolites that accumulate at very low levels in the metabolic pool, will grow. The development of an efficient production method for these compounds will have a great impact in both fields of applied microbiology and industry and will also serve as a good example of a microbial platform for energy-requiring bioprocesses

Genome Sequence of a Mesophilic Hydrogenotrophic Methanogen Methanocella paludicola, the First Cultivated Representative of the Order Methanocellales

We report complete genome sequence of a mesophilic hydrogenotrophic methanogen Methanocella paludicola, the first cultured representative of the order Methanocellales once recognized as an uncultured key archaeal group for methane emission in rice fields. The genome sequence of M. paludicola consists of a single circular chromosome of 2,957,635 bp containing 3004 protein-coding sequences (CDS). Genes for most of the functions known in the methanogenic archaea were identified, e.g. a full complement of hydrogenases and methanogenesis enzymes. The mixotrophic growth of M. paludicola was clarified by the genomic characterization and re-examined by the subsequent growth experiments. Comparative genome analysis with the previously reported genome sequence of RC-IMRE50, which was metagenomically reconstructed, demonstrated that about 70% of M. paludicola CDSs were genetically related with RC-IMRE50 CDSs. These CDSs included the genes involved in hydrogenotrophic methane production, incomplete TCA cycle, assimilatory sulfate reduction and so on. However, the genetic components for the carbon and nitrogen fixation and antioxidant system were different between the two Methanocellales genomes. The difference is likely associated with the physiological variability between M. paludicola and RC-IMRE50, further suggesting the genomic and physiological diversity of the Methanocellales methanogens. Comparative genome analysis among the previously determined methanogen genomes points to the genome-wide relatedness of the Methanocellales methanogens to the orders Methanosarcinales and Methanomicrobiales methanogens in terms of the genetic repertoire. Meanwhile, the unique evolutionary history of the Methanocellales methanogens is also traced in an aspect by the comparative genome analysis among the methanogens