Sugai Kazuhisa

写真a

Affiliation

School of Medicine, Institute for Integrated Sports Medicine (Shinanomachi)

Position

Project Assistant Professor (Non-tenured)/Project Research Associate (Non-tenured)/Project Instructor (Non-tenured)
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Academic Degrees 【 Display / hide 】

  • 博士(獣医保健看護学), Nippon Veterinary and Life Science University, 2024.03

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Papers 【 Display / hide 】

  • Angiotensin-converting gene and hypoxic exercise tolerance: A randomized crossover trial

    Muramoto Y., Momoi M., Nakashima D., Omae K., Sugai K., Daigo K., Iwasawa Y., Ichihara G., Okawara H., Sawada T., Kinoda A., Yamada Y., Kimura T., Sato K., Katsumata Y.

    International Journal of Sports Medicine 46 ( 4 ) 246 - 254 2025

    ISSN  01724622

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    Hypoxic training enhances endurance sports tolerance. However, individual responses vary due to physiological differences. This study investigated the relationship between genetic factors and exercise tolerance in hypoxic conditions. This randomized crossover study included 22 male university students (age 20.8±1.3 years, peak oxygen uptake 54.5±6.5 mL/min/kg). Incremental load tests were conducted to assess the symptomatic limit on separate days under normoxic and hypoxic conditions (oxygen concentration 15.4±0.8%) using an ergometer. The initial test environment was randomized. The peak oxygen uptake and blood lactate were monitored every minute, and Δ peak oxygen uptake (peak oxygen uptake under hypoxia - peak oxygen uptake under normoxia) was calculated. Sixteen genotypes linked to exercise tolerance (such as angiotensin-converting enzyme [ACE]) were examined. Peak oxygen uptake significantly decreased under hypoxia (p<0.01). Δ peak oxygen uptake varied among individuals (minimum: 0.7 and maximum: - 18.9). Among analyzed genetic polymorphisms, ACE-II genotypes showed significantly greater Δ peak oxygen uptake than ACE-ID/ACE-DD genotypes (p=0.02). ACE-II genotypes exhibited lower blood lactate elevation at peak exercise in normoxic (p=0.01) and hypoxic (p=0.03) conditions. Participants with the ACE-II genotype had lower lactate concentrations and greater reductions in peak oxygen uptake under hypoxic conditions. Optimizing hypoxic training requires individualized programs incorporating genetic analysis.

  • Impact of daily administration of blackberry extract on gerbil model of transient cerebral ischemia

    Oda A., Sugai K., Fujisawa M., Hakamata Y., Kobayashi S., Kobayashi E.

    Acta Cirurgica Brasileira 39 2024

    ISSN  01028650

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    Purpose: Blackberries are rich in polyphenols and are a human health food continuously consumed to improve health and reduce diseases caused by aging. Herein, we evaluated the effects of daily blackberry administration before and after transient cerebral ischemia in gerbils. Methods: Blackberry extract (BBE) was orally administered twice a day for two weeks to protect against ischemic events during continuous administration. On the seventh day after administration, the bilateral common carotid arteries were transiently occluded for 5 min. To verify its therapeutic effect, BBE was administered after ischemia using a similar protocol without pre-administration. In both experiments, the number of viable neurons in the CA1 region of the hippocampus was assessed seven days after ischemic treatment. Results: The number of neurons in the group treated with BBE before ischemia was higher than that in the group treated with distilled water (p = 0.0601), and similar to that in the control group. In the BBE administration experiments after ischemia, the number of neurons was significantly reduced compared to that in the control group (p < 0.0001). Conclusion: Continuous BBE intake is expected to prevent or ameliorate ischemic events such as transient cerebral ischemia.

  • Establishment and application of a new 4/6 infarct nephrectomy rat model for moderate chronic kidney disease

    Sugai K., Hirano M., Oda A., Fujisawa M., Shono S., Ishioka K., Tamura T., Katsumata Y., Sano M., Kobayashi E., Hakamata Y.

    Acta Cirurgica Brasileira 39 2024

    ISSN  01028650

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    Purpose: To develop a new 4/6 infarct nephrectomy (INx) model rat mimicking moderate chronic kidney disease (CKD) and to evaluate its application. Methods: We modified the conventional 5/6 INx rat model to create the 4/6 INx model by ligating the renal artery branch to induce infarction of one-third of the left kidney after right kidney removal and compared biochemically and histologically both models. To demonstrate the application of the 4/6 INx model, the effects of a supplementary compound containing calcium carbonate, chitosan, palm shell activated charcoal etc., that is effective for both CKD and its complications, were compared between both models. Results: Impairment of renal function in the 4/6 INx group was significantly more moderate than in the 5/6 INx group (P < 0.05). The 4/6 INx group showed less histological damage in kidney than in the 5/6 INx group. The supplementary compound did not improve CKD in the 5/6 INx group, but ameliorated elevation of blood urea nitrogen in the 4/6 INx group. Conclusion: We developed the 4/6 INx model, which is more moderate than the conventional 5/6 INx model. This model could potentially demonstrate the effectiveness of drugs and supplements intended to prevent CKD and its progression.

  • A neural cell automated analysis system based on pathological specimens in a gerbil brain ischemia model

    Katsumata E., Ranjan A.K., Tashima Y., Takahata T., Sato T., Kobayashi M., Ishii M., Takahashi T., Oda A., Hirano M., Hakamata Y., Sugai K., Kobayashi E.

    Acta Cirurgica Brasileira 39 2024

    ISSN  01028650

    　View Summary

    Purpose: Amid rising health awareness, natural products which has milder effects than medical drugs are becoming popular. However, only few systems can quantitatively assess their impact on living organisms. Therefore, we developed a deep-learning system to automate the counting of cells in a gerbil model, aiming to assess a natural product’s effectiveness against ischemia. Methods: The image acquired from paraffin blocks containing gerbil brains was analyzed by a deep-learning model (fine-tuned Detectron2). Results: The counting system achieved a 79%-positive predictive value and 85%-sensitivity when visual judgment by an expert was used as ground truth. Conclusion: Our system evaluated hydrogen water’s potential against ischemia and found it potentially useful, which is consistent with expert assessment. Due to natural product’s milder effects, large data sets are needed for evaluation, making manual measurement labor-intensive. Hence, our system offers a promising new approach for evaluating natural products.

  • Anaerobic threshold using sweat lactate sensor under hypoxia

    Okawara H., Iwasawa Y., Sawada T., Sugai K., Daigo K., Seki Y., Ichihara G., Nakashima D., Sano M., Nakamura M., Sato K., Fukuda K., Katsumata Y.

    Scientific Reports 13 ( 1 )  2023.12

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    We aimed to investigate the reliability and validity of sweat lactate threshold (sLT) measurement based on the real-time monitoring of the transition in sweat lactate levels (sLA) under hypoxic exercise. In this cross-sectional study, 20 healthy participants who underwent exercise tests using respiratory gas analysis under hypoxia (fraction of inspired oxygen [FiO2], 15.4 ± 0.8%) in addition to normoxia (FiO2, 20.9%) were included; we simultaneously monitored sLA transition using a wearable lactate sensor. The initial significant elevation in sLA over the baseline was defined as sLT. Under hypoxia, real-time dynamic changes in sLA were successfully visualized, including a rapid, continual rise until volitionary exhaustion and a progressive reduction in the recovery phase. High intra- and inter-evaluator reliability was demonstrated for sLT’s repeat determinations (0.782 [0.607–0.898] and 0.933 [0.841–0.973]) as intraclass correlation coefficients [95% confidence interval]. sLT correlated with ventilatory threshold (VT) (r = 0.70, p < 0.01). A strong agreement was found in the Bland–Altman plot (mean difference/mean average time: − 15.5/550.8 s) under hypoxia. Our wearable device enabled continuous and real-time lactate assessment in sweat under hypoxic conditions in healthy participants with high reliability and validity, providing additional information to detect anaerobic thresholds in hypoxic conditions.

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Presentations 【 Display / hide 】

  • CKD Models in Rats Created by Microsurgical Technique

    Sugai K, Fujisawa M, Katsumata Y, Kobayashi E, Hakamata Y.

    The 17th Congress of The International Society for Experimental Microsurgery, 

    2025.05

  • サツマイモ葉柄部の一過性脳虚血スナネズミに対する神経細胞保護効果

    前田友香, 小田朝陽, 菅井和久, 藤澤正彦, 袴田陽二.

    第72回日本実験動物学会総会, 

    2025.05

  • 脳虚血障害スナネズミに対するブラックベリー抽出液の神経細胞保護効果

    小田朝陽, 菅井和久, 藤澤正彦, 袴田陽二.

    第167回日本獣医学会学術集会, 

    2024.09

  • 低酸素環境下での運動トレーニングの骨格筋に及ぼす影響

    菅井和久, 岩澤佑治, 市原元気, 醍醐恭平、桃井瑞生、後藤信一、佐藤和毅、勝俣良紀.

    第167回日本獣医学会学術集会, 

    2024.09

  • 術後イレウス（POI）モデルにおけるクエン酸モサプリド・トレハロース併用時の消化管運動機能評価

    藤澤正彦, 小田朝陽, 菅井和久, 袴田陽二.

    第71回日本実験動物学会総会, 

    2024.05

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