Stability analysis of mathematical models of infectious disease

Dynamics of infectious disease in vivo is described by coupled differential equations. Stability analysis of the complicated systems is difficult without computer calculation, while stability analysis is, in general, important to investigate qualitative behaviour of models. Liu analyzes stability of systems describing HIV dynamics in vivo with a symbolic calculation software. The same method is used for stability analysis of a mathematical model of malaria

Further development in solid-state NMR of half-integer quadrupolar nuclei

Half-integer quadrupolar nuclei constitute more than 70% of the NMRactive nuclei in the Periodic Table. Owing to the presence of anisotropic quadrupolar broadening, high-resolution methods are often required for complete spectral analysis of solid-state NMR spectra of half-integer quadrupolar nuclei. The DOR and DAS techniques require specialist probes whilst the MQMAS and STMAS methods are two-dimensional correlation experiments performed under MAS conditions. The MQMAS experiment has been widely used in materials investigations, whereas the STMAS counterpart is ideal for the study of NMR-insensitive nuclei. This thesis is mainly concerned with the satellite transitions of halfinteger quadrupolar nuclei. Firstly, sensitivity enhancement schemes for the STMAS method are proposed and investigated both theoretically and experimentally using 23Na and 87Rb NMR of simple inorganic compounds, and the applicability and limiting factors of the novel methods are discussed. A recent addition to the aforementioned high-resolution techniques is the STARTMAS experiment. Further development of the STARTMAS approach is described, with respect to the spectral analysis, sensitivity enhancement, and implementation under fast MAS conditions, using 23Na, 87Rb and 69/71Ga NMR at B0 = 9.4 and 20.0 T. A potential area of interest in which the intrinsic sensitivity advantage of the STMAS method can be exploited is the natural abundance 33S solid-state NMR. In the latter half of this thesis, ettringite, a cementitious mineral, is employed to demonstrate the feasibility of high-resolution 33S STMAS NMR at B0 = 9.4 and 20.0 T, with particular emphasis on the implementation of 33S STMAS experiments all performed at the natural abundance levels of the 33S nucleus. Additional investigations are then proposed and performed using 1H- 33S CP-MAS NMR experiments to probe the presence of dynamics in ettringite. Recently, quantum mechanical calculations of solid-state NMR parameters have gained popularity, aiding experimentalists to predict and interpret solid-state NMR spectra. Further investigations of first-principles calculations of solidstate 33S NMR parameters are also presented in this thesis, to support the presence of dynamics around the S nuclei in ettringite

Mathematical model for color pattern and community structure of mat-forming phytobenthos in shallow Antarctic lakes

第3回極域科学シンポジウム/第34回極域生物シンポジウム 11月27日（火） 統計数理研究所 ３階セミナー

Japanese Translation and Validation of Genomic Knowledge Measure in the International Genetics Literacy and Attitudes Survey (iGLAS-GK)

Knowledge of genetics is essential for understanding the results of genetic testing and its implications. Recent advances in genomic research have allowed us to predict the risk of onset of common diseases based on individual genomic information. It is anticipated that more people will receive such estimates of risks based on their genomic data. However, currently, there is no measure for genetic knowledge that includes post-genome sequencing advancements in Japan. In this study, we translated the genomic knowledge measure in the International Genetics Literacy and Attitudes Survey (iGLAS-GK) into Japanese and validated it in a general Japanese adult population (n = 463). The mean score was 8.41 (SD 2.56, range 3–17). The skewness and kurtosis were 0.534 and 0.088, respectively, and the distribution showed a slightly positive skewness. Exploratory factor analysis proposed a six-factor model. Results for 16 of the 20 items of the Japanese version of the iGLAS-GK were comparable to those from previous studies in other populations. These results indicate that the Japanese version is reliable and can be used to measure the genomic knowledge of adults in the general population, and this version of the knowledge measure maintains the multidimensional structure for assessing genomic knowledge

Perfluorooctane Sulfonate (PFOS) and Related Perfluorinated Compounds in Human Maternal and Cord Blood Samples: Assessment of PFOS Exposure in a Susceptible Population during Pregnancy

Fluorinated organic compounds (FOCs), such as perfluorooctane sulfonate (PFOS), perfluorooctanoate (PFOA), and perfluorooctane sulfonylamide (PFOSA), are widely used in the manufacture of plastic, electronics, textile, and construction material in the apparel, leather, and upholstery industries. FOCs have been detected in human blood samples. Studies have indicated that FOCs may be detrimental to rodent development possibly by affecting thyroid hormone levels. In the present study, we determined the concentrations of FOCs in maternal and cord blood samples. Pregnant women 17–37 years of age were enrolled as subjects. FOCs in 15 pairs of maternal and cord blood samples were analyzed by liquid chromatography–electrospray mass spectrometry coupled with online extraction. The limits of quantification of PFOS, PFOA, and PFOSA in human plasma or serum were 0.5, 0.5, and 1.0 ng/mL, respectively. The method enables the precise determination of FOCs and can be applied to the detection of FOCs in human blood samples for monitoring human exposure. PFOS concentrations in maternal samples ranged from 4.9 to 17.6 ng/mL, whereas those in fetal samples ranged from 1.6 to 5.3 ng/mL. In contrast, PFOSA was not detected in fetal or maternal samples, whereas PFOA was detected only in maternal samples (range, < 0.5 to 2.3 ng/mL, 4 of 15). Our results revealed a high correlation between PFOS concentrations in maternal and cord blood (r(2) = 0.876). However, we did not find any significant correlations between PFOS concentration in maternal and cord blood samples and age bracket, birth weight, or levels of thyroid-stimulating hormone or free thyroxine. Our study revealed that human fetuses in Japan may be exposed to relatively high levels of FOCs. Further investigation is required to determine the postnatal effects of fetal exposure to FOCs

Differentiation of preadipocytes and mature adipocytes requires PSMB8

The differentiation of adipocytes is tightly regulated by a variety of intrinsic molecules and also by extrinsic molecules produced by adjacent cells. Dysfunction of adipocyte differentiation causes lipodystrophy, which impairs glucose and lipid homeostasis. Although dysfunction of immunoproteasomes causes partial lipodystrophy, the detailed molecular mechanisms remain to be determined. Here, we demonstrate that Psmb8, a catalytic subunit for immunoproteasomes, directly regulates the differentiation of preadipocytes and additionally the differentiation of preadipocytes to mature adipocytes. Psmb8−/− mice exhibited slower weight gain than wild-type mice, and this was accompanied by reduced adipose tissue volume and smaller size of mature adipocytes compared with controls. Blockade of Psmb8 activity in 3T3-L1 cells disturbed the differentiation to mature adipocytes. Psmb8−/− mice had fewer preadipocyte precursors, fewer preadipocytes and a reduced ability to differentiate preadipocytes toward mature adipocytes. Our data demonstrate that Psmb8-mediated immunoproteasome activity is a direct regulator of the differentiation of preadipocytes and their ultimate maturation