Yohei Kawasaki

Dr. Yohei Kawasaki


Research Focus & Metrics

Academic Career Length

17Years (2010-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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24 August 2014 in AIDS
Verified
Journal Article
Closed access
TNTakeshi Nishijima
Takeshi Nishijima
YKYohei Kawasaki
Yohei Kawasaki
NTNoriko Tanaka
Noriko Tanaka
DMDaisuke Mizushima
Daisuke Mizushima
TATakahiro Aoki
Takahiro Aoki
SOShinichi Oka
Shinichi Oka
To investigate the effect of long-term tenofovir disoproxil fumarate (TDF) use on renal function, especially in patients with low body weight who are vulnerable to TDF nephrotoxicity. A single-center, observational study in Tokyo, Japan. We performed a 10 years cohort study of 792 HIV-1-infected patients. The effect of long-term TDF use on estimated glomerular filtration rate (eGFR) was investigated on treatment-naive patients who started TDF-containing antiretroviral therapy (n = 422) and those who started abacavir-containing antiretroviral therapy as control (n = 370). Three renal endpoints were examined by the logistic regression model: decrement in eGFR of higher than 10 ml/min per 1.73 m relative to the baseline, more than 25% decrement in eGFR, and eGFR lower than 60 ml/min per 1.73 m at least 3 months apart. The loss in eGFR was estimated using linear mixed models for repeated measures. The median weight at baseline was 63 kg. TDF use increased the risk of all three renal outcomes compared with the control group: higher than 10 ml/min per 1.73 m decrement in eGFR [adjusted odds ratio (OR) = 2.1, 95% confidence interval (CI) 1.45-3.14, P < 0.001], more than 25% decrement (adjusted OR = 2.1, 95% CI 1.50-2.90, P < 0.001), and eGFR lower than 60 ml/min per 1.73 m at least 3 months apart (adjusted OR = 3.9, 95% CI 1.62-9.36, P = 0.002). The cumulative mean loss relative to the control after 1, 2, 3, 4, and 5 years of TDF exposure was -3.8, -3.6, -5.5, -6.6, and -10.3 ml/min per 1.73 m, respectively, indicating that the loss in eGFR increased over time (P < 0.001). In this cohort of patients with low body weight, TDF exposure increased the risk of renal dysfunction. Furthermore, the loss in eGFR relative to the control increased continuously up to 5 years.

5 May 2016 in CNS & Neurological Disorders - Drug Targets
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Journal Article
Closed access
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KYKunio Yui
Kunio Yui
YKYohei Kawasaki
Yohei Kawasaki
HYHiroshi Yamada
Hiroshi Yamada
SOShintaro Ogawa
Shintaro Ogawa
The etiology of autism spectrum disorder (ASD) remains unclear; however, the toxic environmental exposure to oxidative stress has been suggested to play an important role in its pathogenesis. A loss of balance between oxidative stress and antioxidant capacity produces an excess of reactive nitrogen species (RNS) such as nitric oxide (NO). Polyunsaturated fatty acids (PUFAs), particularly arachidonic acid, docosahexaenoic acid and eicosapentaenoic acid, are closely related to NO and NO synthase. In the pathophysiology of ASD, NO is related to the activity of primary PUFAs. NO modulates short- and long-term synaptic plasticity and plays essential roles in the regulation of a wide range of physiological processes including neurotransmission. NO affects the function of reactive oxygen species (ROS) in the local cellular milieu, in which biological antioxidants are present. NO plays a double role in the organism showing both neuroprotective and neurotoxic effects. Redox imbalance leads to the activation of the neurotoxic pathway, suggesting crossroads for the neurotoxic or neuroprotective effects of NO. Furthermore, the dual role of NO could depend on the adaptive functions of the antioxidant capacity and oxidative stress-related ROS/RNS as the disease progresses. Increased concentrations of arachidonic acid promote neuronal survival, and the dysregulation of the NO system plays an important role in the pathophysiology of bipolar disorder and recurrent depressive disorders. Therefore, the NO system could provide useful drug targets for these diseases. NO and NO donors also show therapeutic potential for Alzheimer’s disease and schizophrenia with refractory symptoms and cognitive dysfunction.

1 December 2015 in Nutrition Journal
Verified
Journal Article
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KIKazuki Ide
Kazuki Ide
HYHiroshi Yamada
Hiroshi Yamada
NTNorikata Takuma
Norikata Takuma
YKYohei Kawasaki
Yohei Kawasaki
SHShohei Harada
Shohei Harada
YSYuko M. Sagesaka
Yuko M. Sagesaka
Green tea is a beverage with potential effects on cognitive dysfunction, as indicated by results of experimental studies. However, its effects in humans, especially at real-world (typical) consumption levels, are unclear. A double-blind, randomized controlled study was conducted to assess the effects of green tea consumption on cognitive dysfunction (Mini-Mental State Examination Japanese version (MMSE-J) score <28) in Japan. Participants were randomly allocated to the green tea or placebo group, and consumed either 2 g/day of green tea powder (containing 220.2 mg of catechins) or placebo powder (containing 0.0 mg of catechins), respectively, for 12 months. Cognitive function assessments were performed every 3 months using the MMSE-J and laboratory tests. Thirty-three nursing home residents with cognitive dysfunction were enrolled (four men, 29 women; mean age ± SD, 84.8 ± 9.3; mean MMSE-J score ± SD, 15.8 ± 5.4), of whom 27 completed the study. Changes of MMSE-J score after 1 year of green tea consumption were not significantly different compared with that of the placebo group (−0.61 [−2.97, 1.74], least square mean (LSM) difference [95 % CI]; P = 0.59). However, levels of malondialdehyde-modified low-density lipoprotein (U/L), a marker of oxidative stress, was significantly lower in the green tea group (−22.93 [−44.13, −1.73], LSM difference [95 % CI]; P = 0.04). Our results suggest that 12 months green tea consumption may not significantly affect cognitive function assessed by MMSE-J, but prevent an increase of oxidative stress in the elderly population. Additional long-term controlled studies are needed to clarify the effects. UMIN000011668

5 June 2017 in Nature Communications
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Journal Article
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KSKazutaka Shibatomi
Kazutaka Shibatomi
KKKazumasa Kitahara
Kazumasa Kitahara
NSNozomi Sasaki
Nozomi Sasaki
YKYohei Kawasaki
Yohei Kawasaki
IFIkuhide Fujisawa
Ikuhide Fujisawa
SISeiji Iwasa
Seiji Iwasa
Stereoselective halogenation is a highly useful organic transformation for multistep syntheses because the resulting chiral organohalides can serve as precursors for various medicinally relevant derivatives. Even though decarboxylative halogenation of aliphatic carboxylic acids is a useful and fundamental synthetic method for the preparation of a variety of organohalides, an enantioselective version of this reaction has not been reported. Here we report a highly enantioselective decarboxylative chlorination of β-ketocarboxylic acids to obtain α-chloroketones under mild organocatalytic conditions. The present method is also applicable for the enantioselective synthesis of tertiary α-chloroketones. The conversions of the resulting α-chloroketones into α-aminoketones and α-thio-substituted ketones via SN2 reactions at the tertiary carbon centres are also demonstrated. These results constitute an efficient approach for the synthesis of chiral organohalides and are expected to enhance the availability of enantiomerically enriched chiral compounds with heteroatom-substituted chiral stereogenic centres.

19 July 2017 in Nutrients
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Journal Article
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KUKeiko Unno
Keiko Unno
SNShigenori Noda
Shigenori Noda
YKYohei Kawasaki
Yohei Kawasaki
HYHiroshi Yamada
Hiroshi Yamada
AMAkio Morita
Akio Morita
YNYoriyuki Nakamura
Yoriyuki Nakamura
Caffeine, one of the main components in green tea, can interfere with sleep and block the effect of theanine. Since theanine, the main amino acid in tea leaves, has significant anti-stress effects in animals and humans, we examined the effects of green tea with lowered caffeine content, i.e., low-caffeine green tea (LCGT), on stress and quality of sleep of middle–aged individuals (n = 20, mean age 51.3 ± 6.7 years) in a double-blind crossover design. Standard green tea (SGT) was used as the control. These teas (≥300 mL/day), which were eluted with room temperature water, were consumed over a period of seven days after a single washout term. The level of salivary α-amylase activity (sAA), a stress marker, was significantly lower in participants that consumed LCGT (64.7 U/mL) than in those that consumed SGT (73.9 U/mL). Sleep quality was higher in participants that consumed a larger quantity of LCGT. In addition, a self-diagnostic check for accumulated fatigue was significantly lower in those participants that consumed LCGT than SGT. These results indicate that LCGT intake can reduce stress in middle-aged individuals and improve their quality of sleep. The reduction in caffeine is suggested to be a valid reason for enhancing the anti-stress effect of green tea.

23 April 2018 in BMC Psychiatry
Verified
Journal Article
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STShinichiro Tomitaka
Shinichiro Tomitaka
YKYohei Kawasaki
Yohei Kawasaki
KIKazuki Ide
Kazuki Ide
MAMaiko Akutagawa
Maiko Akutagawa
HYHiroshi Yamada
Hiroshi Yamada
TFToshiaki A. Furukawa
Toshiaki A. Furukawa
Recently, item responses and total scores on depression screening scales have been reported to have characteristic distributions in the general population. The distributional pattern of responses to the Patient Health Questionnaire-9 (PHQ-9) in the general population has not been well studied. Thus, we carried out a pattern analysis of the PHQ-9 item responses and total scores in US adults. Data (5372 individuals) were drawn from the 2013–2014 National Health and Nutrition Examination Survey in the United States. The item responses and total score distributions of the PHQ-9 data were investigated with graphical analysis and exponential regression model. Lines of item responses showed the same pattern among the nine items, characterized by crossing at a single point between “not at all” and “several days” and a parallel pattern from “several days” to “nearly every day” on a log-normal scale. The total score distribution of the PHQ-9 exhibited an exponential pattern, except for at the lower end of the distribution. The present results support that the item responses and total scores on the PHQ-9 in the general population show the same characteristic patterns, consistent with the previous studies using the Center for Epidemiologic Studies Depression Scale (CES-D) and Kessler Screening Scale for Psychological Distress (K6).