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Regulation of cell number in the developing Remak's ganglion in the chick
Get PDF新潟大学Niigata University博士（医学）Remak 神経節は⼗⼆指腸から排泄腔の背側を並⾛する神経節であり，⿃類で認められる特異な⾃律神経節と考えられている．仙⾻神経堤細胞に由来する排泄腔部においては，カテコールアミン陽性細胞とコリンアセチルトランスフェラーゼ陽性細胞が混在し，また，この神経節から後腸の腸管神経系に無髄線維を投射することが知られている．Remak神経節の発⽣過程については報告が限定的で，他の神経系で確認されているようなニューロン数の増加と最終的な細胞数をコントロールするプログラム細胞死については詳細が不明である．本研究では，Remak 神経節形成期における総細胞数がE6 からE14 にかけて増加する⼀⽅で，E10~E12 では増加傾向が⼀時的に停滞することが明らかになった．また、初期分化マーカーのIslet-1 陽性細胞がE12 でピークアウトするのと対照的に，Tyrosin Hydroxylase 陽性細胞やコリンアセチルトランスフェラーゼ陽性細胞がE8 から経時的に増加傾向を呈することが明らかになった．更に神経系の発⽣過程で観察される細胞死について検証したところ，E6~E14の全てのステージでRemak神経節における細胞死が観察された．この細胞死は２層性の推移を⽰しており，前半と後半で異なる細胞が除去されていることが⽰唆された．また細胞死で失われる細胞の規模は，他の神経系の発⽣で認められる50％前後と⽐して，極めて限定的であることが明らかになった．プログラム細胞死の多くが標的由来シグナルの影響を受けることから，Remak 神経節の標的がENS を含む点で通常の⾃律神経節後ニューロンのような細胞数のコントロールと異なっている可能性が考えられた．新大院博（医）第1145
2020年新潟県高齢者脆弱性大腿骨近位部骨折調査において超高齢者の骨折発生は増加した
Get PDF新潟大学Niigata University博士（医学）Introduction A 2015 study showed a decreasing trend in the incidence of osteoporotic hip fractures in Niigata Prefecture, Japan, which had been increasing. This study aimed to investigate the incidence of osteoporotic hip fractures in 2020, deter-mine the long-term change in the incidence of hip fractures from 1985 to 2020, and assess whether the decline in fracture incidence since 2010 has continued. Materials and Methods We obtained data from the registration forms submitted by hospitals and clinics of patients who lived in Niigata Prefecture and were diagnosed with osteoporotic hip fracture through a survey conducted from January 1, 2020 to December 31, 2020. Results In 2020, 3,369 hip fractures were recorded in Niigata Prefecture. Although the overall incidence of age-specific hip fractures decreased, it increased in patients aged ≥ 90 years, regardless of sex. The proportion of patients receiving anti-osteoporosis drugs prior to hip fracture increased from 7.6% in 2004 to 17.3% in 2020. Notably, surgical treatment should be performed as early as possible, and the preoperative waiting time was 2.9 days, which was mainly due to holidays. Conclusion The incidence of hip fractures in Niigata Prefecture has gradually increased over the past 35 years, with an increasing change observed in the very elderly recently in 2020. Although the treatment of osteoporotic hip fractures in Niigata Prefecture is adequate, improvements may include increasing the rate of adoption of osteoporosis treatment further and decreasing the number of days of preoperative waiting.Journal of Bone and Mineral Metabolism. 2023, 41, 533-541.新大院博（医）第1151
持続性知覚性姿勢誘発めまいにおける前庭-視覚 : 体性感覚野と空間認知領域との機能的結合性の変化 : 視覚刺激前後の安静時機能的MRIの検討
Get PDF新潟大学Niigata University博士（医学）Introduction: Persistent postural-perceptual dizziness (PPPD) is a functional chronic vestibular syndrome with symptom exacerbation by upright posture,motion, and complex visual stimuli. Among these exacerbating factors, visual exacerbation is the most specific characteristic of PPPD requiring further investigation. We hypothesized that stimulus-induced changes occur in the functional connectivity (FC) rather than simple neural activation that is involved in visual stimulation. The present study aimed to identify the neural basis of PPPD by investigating FC before and after visual stimulation. Methods: Eleven patients with PPPD and 11 age- and sex-matched healthy controls (HCs) underwent resting-state fMRI (rs-fMRI) before and after task-based fMRI with visual stimuli. Results: At pre-stimulus, FC between the vestibular cortex and visual areas was low, while that between the somatosensory and visual areas was high in PPPD compared with that in HCs. FC between the visuospatial (parahippocampal gyrus) and spatial cognitive areas (inferior parietal lobule) was elevated in PPPD even in the pre-stimulus condition, which no longer increased at post-stimulus as observed in HCs. In the post-stimulus condition, FC between the visual and spatial cognitive areas and that between the visual and prefrontal areas increased compared with that in the pre-stimulus condition in PPPD. Task-based fMRI demonstrated that no brain regions showed different activities between the HC and PPPD groups during visual stimulation. Discussion: In PPPD, vestibular inputs may not be fully utilized in the vestibulo-visuo-somatosensory network. Given that the FC between visuospatial and spatial cognitive areas increased even in HCs after visual stimuli, elevated status of this FC in combination with the high FC between the somatosensory and visual areas would be involved in the visual exacerbation in PPPD. An increase in FC from the visual areas to spatial cognitive and prefrontal areas after visual stimuli may account for the prolonged symptoms after visual exacerbation and anxious status in PPPD.Frontiers in Neurology. 2023, 14, 1215004.新大院博（医）第1152
髄床底部への意図的穿孔形成がマウス歯の再植後の歯髄治癒過程に及ぼす影響
Get PDF新潟大学Niigata University博士（保健学）Objectives: Shortening the root of a mouse molar prior to tooth replantation results in early revascularization in the pulp cavity and activation of the dental pulp quiescent stem cells. This study aimed to elucidate the effects of perforating the floor of the pulp chamber on pulpal healing after tooth replantation in order to determine whether this strategy is a valid methodology to promote early revascularization into the pulp. Methods: The maxillary first molars of three-week-old Crlj:CD1 mice were extracted and repositioned into the original socket: the left teeth were immediately replanted (control group: CG), whereas the floor of the pulp chamber of the right teeth was perforated with a tungsten carbide bur before tooth replantation (experimental group: EG). The samples were collected from three days to eight weeks after the operation. In addition to the TUNEL assay, immunohistochemistry for Nestin, CK14, and Ki-67 was conducted. Results: Early revascularization occurred with the decrease of apoptosis and an increase in cell proliferation to facilitate the pulpal healing in the EG compared with the CG. The rate of Nestin-positive perimeter in the distal root significantly increased on days 5 and 14 as well as Nestin-positive hard tissue on day 14. On day 7, the number of epithelial cell rests of Malassez in the EG significantly decreased, making the EG susceptible to ankylosis at the floor. Conclusions: Intentionally perforating the floor of the pulp chamber provides a route via the floor for early revascularization, resulting in the better pulpal healing after tooth replantation.Journal of Oral Biosciences. 2023, 65(1), 31-39.新大院博(保)第54
ウキクサ亜科(サトイモ科)の進化生物学的研究 : 特に東アジア産アオウキクサ属Lemnaを中心として
Get PDF新潟大学Niigata University博士（理学）Aquatic plants are a polyphyletic plant group that depend on the aquatic environment for part of their life history. Each of these plants is considered to have adapted and speciated into a waterside environment; however, evolutionary and taxonomic research has been stagnant because of the difficulty in investigation and observation compared with that in general terrestrial plants. Lemna L. (Araceae, Lemnoideae) is a good model plant for aquatic botanical research. It is the largest genus in the subfamily Lemnoideae and is a tiny floating aquatic plant that is widely distributed throughout the world, except in the polar areas. Because Lemna species have simple organs and their flowers are rare, identification is difficult, and taxonomic challenges remain. Therefore, in the present study, the genetic diversity, morphology, floral morphology, interspecific hybridization, and distribution of Lemna and their relationship with evolution and speciation are discussed in five chapters. In Chapter 1, I summarize the taxonomic challenges, relationships between evolution and species differentiation, genetic diversity, morphological characteristics, flower morphology, and interspecies hybridization of Lemna. In Chapter 2, I examined whether the physiological and morphological characteristics were phenotypic plasticity or a reflection of species differences in Le. aequinoctialis Welw. and Le. aoukikusa Beppu et Murata. Physiological analysis of 11 strains revealed two types of flowers: protogynous and homogamous. Physiological group A, which was protogynous, was self-incompatible, and mature seeds could not be obtained. In contrast, mature seeds were obtained from group B, which was homogamous. These two groups were morphologically different, consistent with the characteristics of Le. aequinoctialis and Le. aoukikusa, respectively. Chloroplast DNA-based phylogenetic analyses also supported the division of these two groups, and it was concluded that Le. aequinoctialis and Le. aoukikusa are independent taxa. In Chapter 3, I estimated the clonality of the Japanese Le. trisulca L. based on genome-wide Single-nucleotide polymorphisms (SNPs) data, clarified the population structure, and evaluated the relationship between morphology (root presence and number of frond veins) and genetic features. Based on the genetic distance calculated for three relationships, which are "within individual", "among individuals in the same population", and "between population", there was no significant difference in genetic distance between "within individual" and "among individuals in the same population" relationships. This suggests that each population is usually maintained by the clonal reproduction of a single plant, that each population does not share the same individual, and that migration among populations is likely caused by seeds. This seems to be because submerged plants have a low tolerance to drying conditions, making it difficult for leaflets to disperse long distances. No relationship was detected between the morphological diversity and genetic characteristics in the presence frond veins or their number. In Chapter 4, to clarify the relationship between interspecific hybridization, differentiation of morphological traits, and speciation in Lemna, I investigated physiological and morphological variation, pollen germination rate, and phylogenetic relationships for Japanese Le. minor L., Le. japonica Landolt, and Le. turionifera Landolt in section Lemna. Chloroplast DNA analysis yielded three haplotypes and clustering analysis based on genome-wide SNP data revealed three genetic clusters in the three Japanese species. As flower characteristics of Le. japonica have not been sufficiently reported, I could not identify the actual Le. japonica. Based on Le. japonica type material (7182) observation and comparison, cluster B (haplotype J), which has a light reddish spathe and never an open anther, was classified as Le. japonica. Subcluster a (haplotype M), with a transparent spathe, was identified as Le. minor. Cluster C (haplotype T), with strong reddish spathe and dehiscent anthers, was identified as Le. turionifera. There was only one substitution between haplotypes J and M; however, there were 16 and 15 substitutions within haplotypes J and T, M and T, respectively. The three species were also morphologically distinguished in Principal Component Analysis (PCA), and the variances in frond number, frond thickness, ovary diameter, and stigma width were high. In the estimation of population demographic history, the scenario in which Le. minor and Le. turionifera hybridized approximately 6,850 (2,100-13,100) generations ago was most highly supported, and the possibility that Le. japonica originating from hybridization, was supported, as previously reported. In the pollen germination rate test, putative parental species Le. turionifera had a significantly higher germination rate than Le. minor, whereas pollen from Le. japonica seeds did not germinate. These results suggested that the combination of the putative parental species Le. minor as the female seed parent and Le. turionifera as a male pollen donor, as deduced from chloroplast DNA analysis. Additionally, the distribution of Le. minor and Le. japonica was divided into Northern and Southern Japan, which may reflect the seed-formation ability of the two species. In Chapter 5, I report two new distributions of the Lemnoideae plants (Landoltia punctata and Le. turionifera) and their habitat information to date based on field observations.新大院博(理)第485
Study on the mass balance of "avalanche accumulate type" very small glaciers and perennial snow patches in the northern Japanese Alps
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Study on Practical Application of DC Induction Heating Type Aluminum Billet Heating Device Using High Temperature Superconducting Magnet
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東日本における流域特性を使用したベースフローと低流量指数の回帰モデリング
Get PDF新潟大学Niigata University博士（農学）Baseflow is the portion of streamflow derived from delayed subsurface pathways. The baseflow index (BFI) is a ratio of baseflow to total streamflow, and is an important hydrological variable when linking watershed characteristics to baseflow. In addition, the BFI and runoff trend analysis could be used to assess the impact of climate change and human activity on river systems. The 'smoothed minima' procedure of baseflow separation was applied to streamflow data (29-67 years) from twenty-six gauges of watersheds in eastern Japan. The Mann-Kendall statistical test and Sen's slope estimator were used to identify trends and estimate the rate of change in annual and seasonal runoff and BFI per decade at 0.01 and 0.05 significance levels. According to what I know, this is the first study to investigate long-term trends in runoff and BFI for watersheds in the large-scale region of eastern Japan. Results showed significant trends in annual runoff and BFI, with a concentration of significant seasonal trends occurring in winter, with five gauges showing trends in runoff and nine gauges showing trends in BFI. The results suggest that the response of annual and seasonal runoff and BFI to climate change can already be seen, which implies that policymakers need more information on the impacts of climate change and human activities to manage water resources sustainably. A convenient technique was suggested for the matching strip method in determining the recession constant of the master recession curve using the ratio of flow over successive days (Qn+1/Qn). The procedure was applied to 29 basins (6.1-740km2) in eastern Japan to build linear regression models which estimate low flow indices through the recession constant (λ), and either mean annual precipitation or mean annual runoff. Statistically, significant models with an additive format (no log transformation) were built for dependent variables; Q710 (7-day 10-year low flow), and Q9710 (10-year low flow exceeded 97% of time) in the case of all basins, and in particular, the case of basins classified into sedimentary or igneous lithology with the adjusted R2 up to 0.784. In case of all basins lumped together, regression models based on mean annual runoff as the second independent variable performed better than those based on mean annual precipitation, with adjusted R2 of 0.705 and 0.717 for the Q710 and Q9710 models, respectively. The thesis also developed models with a multiplicative format (log transformation) to estimate annual BFI and Q710 flow index using the mean annual runoff and either mean elevation or maximum elevation. Five out of the six models developed were significant, with adjusted R2 values up to 0.482 (Q710 model for sedimentary lithology). These significant regression models could be applied to poorly gauged watersheds to manage water resources sustainably in eastern Japan and contribute towards achieving SDG6.新大院博(農)第237