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Kamishima T, Hirabe C, Myint KZY, Taguchi J. Divergent progression pathways in male androgenetic alopecia and female pattern hair loss: Trichoscopic perspectives. J Cosmet Dermatol 2024; 23:1828-1839. [PMID: 38189587 DOI: 10.1111/jocd.16177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Revised: 11/22/2023] [Accepted: 12/28/2023] [Indexed: 01/09/2024]
Abstract
BACKGROUND Despite similarities in progressive miniaturization of hair follicles and transition of terminal hairs to vellus hairs, insufficient trichoscopic comparisons between male androgenetic alopecia (MAGA) and female pattern hair loss (FPHL) hinder our ability to select effective treatments. AIM Our study aimed to explore gender-specific trichoscopic characteristics of MAGA and FPHL, while formulating hypotheses regarding the progression of these conditions across clinical stages. METHODS We classified 126 male MAGA subjects using Hamilton-Norwood Classification and 57 FPHL subjects using adopted Sinclair Scale. Subsequently, we analyzed nine trichoscopic factors divided into three categories: hair-diameter related, hair-number per follicular unit related, and hair density related factors. RESULTS Of the nine quantitative trichoscopic factors, hair-diameter and hair-number per follicular unit showed strong correlations with clinical stages in both genders. Hair density, a common trichoscopic factor for hair loss evaluation, weakly correlated with clinical stages in FPHL, but not at all in MAGA. In addition, MAGA was characterized by a progressive reduction in hair-diameter, followed by a reduction in hair-number per follicular unit. FPHL, on the contrary, showed the opposite progression. CONCLUSIONS Trichoscopic factors vary with disease severity in a gender-specific manner. Our research highlights that MAGA and FPHL involve two distinct streams: hair-diameter decreasing by hair follicle miniaturization (Stream 1), and hair-number per follicular unit decreasing by hair follicle tri-lineage niche dysfunction (Stream 2). MAGA typically starts from Stream 1 to Stream 2, while FPHL starts from Stream 2. These diverse progression pathways underscore the importance of personalized treatment approaches.
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Affiliation(s)
- Tomoko Kamishima
- Department of Dermatology, Tokyo Midtown Skin/Aesthetic Clinic Noage, Tokyo, Japan
| | - Chie Hirabe
- Department of Dermatology, Tokyo Midtown Skin/Aesthetic Clinic Noage, Tokyo, Japan
| | - Khin Zay Yar Myint
- Tokyo Midtown Center for Advanced Medical Science and Technology, Tokyo, Japan
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Myint KZY, Yoshikata R, Taguchi J. Comparison of the five different definitions of equol producers: The relationship between blood and urine equol concentrations and blood parameters in 466 healthy men and women. Clin Chim Acta 2024; 557:117885. [PMID: 38527713 DOI: 10.1016/j.cca.2024.117885] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 03/17/2024] [Accepted: 03/21/2024] [Indexed: 03/27/2024]
Abstract
BACKGROUND AND AIMS No studies have compared various definitions of "equol producers" until now. Therefore, we aimed to explore the accuracy of five different definitions of equol producers (EQP) and their associations with health benefits. METHODS This is a cross-sectional study of 466 healthy Japanese men and women aged between 22 and 88 years. Equol producer proportions were calculated from their serum and urine isoflavone concentrations using five commonly used definitions. We then examined their accuracy, and associations with the blood parameters. RESULTS Proportions of equol ranged from 29 % in the most stringent definition to 47.6 % in the most sensitive definition. EQP identified under all definitions had significantly low serum PSA1 levels compared to nonequol producers (NEQP). The most stringent definition, which is defined as the urinary equol level of 1.0 μM and above, corresponded to the highest median serum equol level and was associated with better health outcomes. Male EQP identified by this definition seemed to have reduced risk of LDL2-hypercholesterolemia by 50 %, and female EQP identified by this definition seemed to have lower risk of high hs-CRP,3 compared to NEQP. Both the first and second stringent definition, which is defined as the serum equol level of 1.0 ng/mL and above, was associated with lower thyroid stimulating hormone level. CONCLUSIONS More stringent definitions were associated with better parameters in general. Combined with the dietary inquires, a reliable definition for equol producer is crucial to evaluate the health benefits of equol.
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Affiliation(s)
| | - Remi Yoshikata
- Tokyo Midtown Medical Center, Minato-ku, Tokyo, Japan; Hamasite Clinic, Minato-ku, Tokyo, Japan
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Kamishima T, Hirabe C, Ohnishi T, Taguchi J, Myint KZY, Koga S. Trichoscopic evaluation of dental pulp stem cell conditioned media for androgenic alopecia. J Cosmet Dermatol 2023; 22:3107-3117. [PMID: 37154468 DOI: 10.1111/jocd.15799] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 04/16/2023] [Accepted: 04/21/2023] [Indexed: 05/10/2023]
Abstract
BACKGROUND Conditioned media (CM) derived from mesenchymal stem cells (MSC) is known to induce hair regrowth in androgenic alopecia. OBJECTIVES The objectives of the study were to assess the efficacy and safety of one type of MSC-CM, the CM derived from dental pulp stem cells obtained from human exfoliated deciduous teeth (SHED-CM) and to compare the efficacy of SHED-CM with and without dihydrotestosterone synthesis inhibitor (DHT-inhibitor). METHODS Eighty-eight male androgenic alopecia subjects with Hamilton-Norwood Classification (H-N C) I-VII were evaluated by trichoscopy to explore which trichoscopic factors statistically correlated with H-N C. After being screened, 33 subjects received six SHED-CM treatments at 1-month intervals. Clinical severity was assessed through global and trichoscopic images from baseline to 9th month. RESULTS SHED-CM was effective for 75% of subjects regardless of disease severity, concomitant DHT-inhibitor use, and age. Adverse effects including pain and small hemorrhages were transient and mild. We also found that clinical hair status evaluated by absolute values of three quantitative trichoscopic factors (maximum hair diameter, vellus hair rate, and multi-hair follicular unit rate) showed a good correlation with H-N C stages, and what is more-a scoring system of these three factors can be a possible predictor of SHED-CM efficacy. CONCLUSIONS We have shown that SHED-CM provides global and trichoscopic image improvement for androgenic alopecia, regardless of concomitant DHT-inhibitor use.
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Affiliation(s)
- Tomoko Kamishima
- Department of Dermatology, Tokyo Midtown Skin/Aesthetic Clinic Noage, Tokyo, Japan
| | - Chie Hirabe
- Department of Dermatology, Tokyo Midtown Skin/Aesthetic Clinic Noage, Tokyo, Japan
| | | | | | - Khin Zay Yar Myint
- Tokyo Midtown Center for Advanced Medical Science and Technology, Tokyo, Japan
| | - Shoji Koga
- Ginza Solaria Clinic, Tokyo, Japan
- Panagy Co., Ltd., Tokyo, Japan
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Myint KZY, Shimabuku M, Horio R, Kaneda M, Shimizu Y, Taguchi J. Identification of circulating tumour DNA (ctDNA) from the liquid biopsy results: Findings from an observational cohort study. Cancer Treat Res Commun 2023; 35:100701. [PMID: 37094468 DOI: 10.1016/j.ctarc.2023.100701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 03/02/2023] [Accepted: 03/24/2023] [Indexed: 04/26/2023]
Abstract
Liquid biopsies can be a rapid, cost-effective and non-invasive alternative to tumour biopsies for detecting genetic mutations in somatic tumours. Genetic profiling of liquid biopsies can also be used to identify novel antigens for targeted therapy, provide updated information on disease prognosis and evaluate treatment efficacy. In this study, we aimed to examine mutations that could be identified in liquid biopsy and their distribution in a small study cohort. We studied the genomic profiles of 99 blood samples from 85 patients with 21 different types of cancer using two commercially available liquid biopsy tests. The mean circulating free DNA (cfDNA) concentration was 162.7 ± 352.3 nanograms per 20 millilitres. Amongst cfDNA, the circulating tumour DNA (ctDNA) percentage ranged from 0.006% to 90.6%. With the exception of samples with gene amplification and high microsatellite instability, the number of mutations in each sample varied from zero to 21, with an average of 5.6 mutations in each patient. Amongst these mutations, nonsynonymous mutations were the most frequently observed type of mutation (90% of the sample, with an average frequency of 3.6 mutations per patient). Mutations were observed in 76 different genes. TP53 mutations constituted more than 16% of the detectable mutations, especially in non-small cell lung cancer. All the tumour types, except the ovary, kidney and apocrine gland tumours, harboured at least one type of TP53 mutation. KRAS (mainly in pancreatic cancer) and PIK3CA (mostly in breast cancer) mutations, were responsible for an additional 10% of the mutations in the studied samples. The tumour mutations were specific to each patient, as approximately 94.7% of the mutations were so unique that there was almost no duplication amongst the patients. These findings indicate that liquid biopsy can detect specific molecular changes of tumour, which is useful for precision oncology and personalized cancer treatment.
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Affiliation(s)
- Khin Zay Yar Myint
- Centre for Advanced Medical Science and Technology, Tokyo Midtown Medical Center, Japan
| | - Masamori Shimabuku
- Centre for Advanced Medical Science and Technology, Tokyo Midtown Medical Center, Japan
| | - Ruriko Horio
- Centre for Advanced Medical Science and Technology, Tokyo Midtown Medical Center, Japan
| | - Munehisa Kaneda
- Centre for Advanced Medical Science and Technology, Tokyo Midtown Medical Center, Japan
| | - Yoko Shimizu
- Centre for Advanced Medical Science and Technology, Tokyo Midtown Medical Center, Japan
| | - Junichi Taguchi
- Centre for Advanced Medical Science and Technology, Tokyo Midtown Medical Center, Japan.
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Yoshikata R, Yamaguchi M, Mase Y, Tatsuzuki A, Myint KZY, Ohta H. Age-Related Changes, Influencing Factors, and Crosstalk Between Vaginal and Gut Microbiota: A Cross-Sectional Comparative Study of Pre- and Postmenopausal Women. J Womens Health (Larchmt) 2022; 31:1763-1772. [PMID: 36374244 DOI: 10.1089/jwh.2022.0114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Objective: The ideal vaginal environment is maintained by Lactobacillus species, which keep the vagina clean and free of infections, boost fertility and immunity. Age-related decline in estrogen affects Lactobacillus population, leading to dominance of nonoptimal species and increased diversity in vaginal microbiota. In this study, we compared the differences between the vaginal microbiota of pre- and postmenopausal women. We also examined the relationships between vaginal and gut microbiota, their relationships with sex hormones and equol-producing ability. Materials and Methods: This was a cross-sectional study of 35 premenopausal and 35 postmenopausal women (age range: 27-76 years). We compared parameters such as the composition of the gut and vaginal microbiota, vaginal pH, estradiol, follicular stimulating hormone, and urinary equol concentration. Results: In the vaginal microbiota of premenopausal women, Lactobacillus species constituted ∼71.98%, and nonoptimal species constituted ∼16.87%. They were 10.08% and 26.78%, respectively, in the vaginal microbiota of postmenopausal women. The proportion of Lactobacillus was significantly low, whereas microbial diversity and vaginal pH were significantly high (p < 0.0001) in postmenopausal women. The compositions of the vaginal microbiota were significantly different in pre- and postmenopausal women. However, such differences were not noticeable in the gut microbiota. Urinary equol production had no significant correlation with vaginal microbiota, although it had significant relationships with gut microbiota in postmenopausal women. In both groups, the proportions of vaginal Lactobacillus were inversely correlated with vaginal microbial diversity and vaginal pH. Conclusion: Postmenopausal women had significantly low Lactobacillus and high nonoptimal species in their vaginal flora, whereas such age-related differences were not identified in gut microbiota. Urinary equol concentration had significant correlation with gut microbiota in postmenopausal women only. This study was registered with the University Hospital Medical Information Network (UMIN) Clinical Trial Registry (Trial registration No.: UMIN000043944).
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Affiliation(s)
- Remi Yoshikata
- Hamamatsucho Hamasite Clinic, Minato-ku, Tokyo, Japan.,Tokyo Midtown Medical Center, Minato-ku, Tokyo, Japan
| | | | - Yuri Mase
- Hamamatsucho Hamasite Clinic, Minato-ku, Tokyo, Japan.,Tokyo Midtown Medical Center, Minato-ku, Tokyo, Japan
| | - Ayano Tatsuzuki
- Hamamatsucho Hamasite Clinic, Minato-ku, Tokyo, Japan.,Tokyo Midtown Medical Center, Minato-ku, Tokyo, Japan
| | | | - Hiroaki Ohta
- Kawasaki Medical School Hospital, Okayama, Japan.,Fujita Health University Hospital, International Medical Center, Aichi, Japan
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Shimabuku M, Taguchi J, Zay Yar Myint K, Kaneda M, Kashihara K, Kusano T, Horio R, Shimizu Y, Hirokawa K. [Ⅳ. Dendritic Cell Immunotherapy as Pancreatic Cancer Treatment]. Gan To Kagaku Ryoho 2022; 49:1070-1075. [PMID: 36281598] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Affiliation(s)
- Masamori Shimabuku
- Center for Advanced Medical Science and Technology, Tokyo Midtown Medical Center
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Mori S, Onda K, Fujita S, Suzuki T, Ikeda M, Zay Yar Myint K, Hikage J, Abe O, Tomimoto H, Oishi K, Taguchi J. Brain atrophy in middle age using magnetic resonance imaging scans from Japan’s health screening programme. Brain Commun 2022; 4:fcac211. [PMID: 36043138 PMCID: PMC9416065 DOI: 10.1093/braincomms/fcac211] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 06/12/2022] [Accepted: 08/20/2022] [Indexed: 12/21/2022] Open
Abstract
Although health screening plays a key role in the management of chronic diseases associated with lifestyle choices, brain health is not generally monitored, remaining a black box prior to the manifestation of clinical symptoms. Japan is unique in this regard, as brain MRI scans have been widely performed for more than two decades as part of Brain Dock, a comprehensive health screening programme. A vast number of stored images (well over a million) of longitudinal scans and extensive health data are available, offering a valuable resource for investigating the prevalence of various types of brain-related health conditions occurring throughout adulthood. In this paper, we report on the findings of our preliminary quantitative analysis of T1-weighted MRIs of the brain obtained from 13 980 subjects from three participating sites during the period 2015–19. We applied automated segmentation analysis and observed age-dependent volume loss of various brain structures. We subsequently investigated the effects of scan protocols and the feasibility of calibration for pooling the data. Last, the degree of brain atrophy was correlated with four known risk factors of dementia; blood glucose level, hypertension, obesity, and alcohol consumption. In this initial analysis, we identified brain ventricular volume as an effective marker of age-dependent brain atrophy, being highly sensitive to ageing and evidencing strong robustness against protocol variability. We established the normal range of ventricular volumes at each age, which is an essential first step for establishing criteria used to interpret data obtained for individual participants. We identified a subgroup of individuals at midlife with ventricles that substantially exceeded the average size. The correlation studies revealed that all four risk factors were associated with greater ventricular volumes at midlife, some of which reached highly significant sizes. This study demonstrates the feasibility of conducting a large-scale quantitative analysis of existing Brain Dock data in Japan. It will importantly guide future efforts to investigate the prevalence of large ventricles at midlife and the potential reduction of this prevalence, and hence of dementia risk, through lifestyle changes.
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Affiliation(s)
- Susumu Mori
- Department of Radiology, Johns Hopkins University, School of Medicine , 330 Traylor Bldg, 217 Rutland Ave, Baltimore, MD 21205 , USA
| | - Kengo Onda
- Tokyo Medical and Dental University , 1 Chome-5-45 Yushima, Bunkyo City, Tokyo 113-0034 , Japan
| | - Shohei Fujita
- Department of Radiology, The University of Tokyo, Graduate School of Medicine , 7-3-1 Hongo, Bunkyo City, Tokyo 113-0033 , Japan
| | - Toshiaki Suzuki
- Resorttrust.Inc, Engyou Bldg.8F , Roppongi 7-15-14, Minato-ku, Tokyo 106-0032 , Japan
| | - Mikimasa Ikeda
- Resorttrust.Inc, Engyou Bldg.8F , Roppongi 7-15-14, Minato-ku, Tokyo 106-0032 , Japan
| | - Khin Zay Yar Myint
- Advanced Medical Care Inc. , Midtown Tower 6F, Akasaka 9-7-1, Minato-ku, Tokyo 107-6206 , Japan
| | - Jun Hikage
- Resorttrust.Inc, Engyou Bldg.8F , Roppongi 7-15-14, Minato-ku, Tokyo 106-0032 , Japan
| | - Osamu Abe
- Department of Radiology, The University of Tokyo, Graduate School of Medicine , 7-3-1 Hongo, Bunkyo City, Tokyo 113-0033 , Japan
| | - Hidekazu Tomimoto
- Department of Neurology, Hidekazu Tomimoto, Mie University 2-174 , Edobashi, Tsu, Mie 514-0001 , Japan
| | - Kenichi Oishi
- Department of Radiology, Johns Hopkins University, School of Medicine , 330 Traylor Bldg, 217 Rutland Ave, Baltimore, MD 21205 , USA
| | - Junichi Taguchi
- Tokyo Midtown Clinic , 9-7-1-6F Akasaka, Minato, Tokyo 107-6206 , Japan
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Yoshikata R, Myint KZY, Ohta H, Ishigaki Y. Effects of an equol-containing supplement on advanced glycation end products, visceral fat and climacteric symptoms in postmenopausal women: A randomized controlled trial. PLoS One 2021; 16:e0257332. [PMID: 34506596 PMCID: PMC8432832 DOI: 10.1371/journal.pone.0257332] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Accepted: 06/17/2021] [Indexed: 11/28/2022] Open
Abstract
INTRODUCTION Equol, an isoflavone derivative whose chemical structure is similar to estrogen, is considered a potentially effective agent for relieving climacteric symptoms, for the prevention of lifestyle-related diseases, and for aging care in postmenopausal women. We investigated the effect of an equol-containing supplement on metabolism and aging and climacteric symptoms with respect to internally produced equol in postmenopausal women. METHODS A single-center, randomized controlled trial (registration number: UMIN000030975) on 57 postmenopausal Japanese women (mean age: 56±5.37 years) was conducted. Twenty-seven women received the equol supplement, while the remaining received control. Metabolic and aging-related biomarkers were compared before and after the 3-month intervention. Climacteric symptoms were assessed every month using a validated self-administered questionnaire in Japanese postmenopausal women. RESULTS Three months post-intervention, the treatment group showed significant improvement in climacteric symptoms compared to the control group (81% vs. 53%, respectively, p = 0.045). We did not observe any beneficial effect on metabolic and aging-related biomarkers in the intervention group. However, in certain populations, significant improvement in skin autofluorescence, which is a measurement of AGE skin products, and visceral fat area was observed, especially among equol producers. CONCLUSION Women receiving equol supplementation showed improved climacteric symptoms. This study offered a new hypothesis that there may be a synergy between supplemented equol and endogenously produced equol to improve skin aging and visceral fat in certain populations.
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Affiliation(s)
- Remi Yoshikata
- Hamasite Clinic, Minato-ku, Tokyo, Japan
- Tokyo Midtown Medical Center, Minato-ku, Tokyo, Japan
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Yoshikata R, Myint KZY, Ohta H. Effects of Equol Supplement on Bone and Cardiovascular Parameters in Middle-Aged Japanese Women: A Prospective Observational Study. J Altern Complement Med 2018; 24:701-708. [PMID: 29722549 PMCID: PMC6065522 DOI: 10.1089/acm.2018.0050] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Objective: To examine changes in the bone and cardiovascular parameters and tolerability in middle-aged Japanese women taking equol supplement for a year. Design: This was a prospective observational study. Subjects and Setting: Participants were 74 women receiving outpatient care at Hamasite Medical Clinic, Minato-ku, Tokyo, from 2013 to 2015. Interventions: Participants received per oral equol-containing supplement, 10 mg/day. Outcome measures: The primary outcome measures were percent changes in bone and cardiovascular parameters after 1 year supplementation with equol. The secondary measures included factors affecting the parameter changes and adverse effects associated with equol use for a year. Results: Reduction in arterial stiffness was observed after 12 months of equol supplement (1402.3 cm/s vs.1367.3 cm/s, p < 0.001). Significant reductions in respective parameters were observed in women with moderate and high risk for arteriosclerosis (median [95% confidence interval]: −3.2% [−5.79 to −0.74]; −12.65% [−18.52 to −4.28]; respectively); hypertriglyceridemia −45.53% [−70.24 to −5.58]; bone resorption risk (−15.15% [−23.71 to 1.56]; and bone fracture risk −26.68% [−76.43 to −5.99]. All 15 women with high baseline parathyroid hormone levels had achieved a median of 50% [−54.11 to −31.69] reduction from their baseline values. These associations were further confirmed in the results of multiple linear regression analysis. There were no reported adverse events or abnormal findings in the blood chemistry, Pap smear, mammography, and transvaginal ultrasound during periodic follow-ups. Conclusion: One year equol supplement was tolerable and induced improvement of certain bone and cardiovascular parameters, especially in higher risk groups. Further controlled studies are needed to explore long-term equol use for wellbeing of middle-aged women.
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Affiliation(s)
- Remi Yoshikata
- 1 Hamasite Clinic , Minato-ku, Japan .,2 Tokyo Midtown Medical Center , Minato-ku, Japan
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Myint KZY, Nonaka D, Jimba M, Nanishi K, Poudel KC, Yasuoka J, Miyagi M, Shinjo M, Kobayashi J. Unnecessary Dieting Intention and Behavior among Female Students in Naha City, Japan. Trop Med Health 2015; 43:131-40. [PMID: 26161031 PMCID: PMC4491491 DOI: 10.2149/tmh.2014-33] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Accepted: 03/17/2015] [Indexed: 12/15/2022] Open
Abstract
Weight concerns and dieting are prevalent among female adolescents both in Western and Asian countries. They can result in negative psychological and physiological consequences. This study aimed to examine the relative importance of social and personal factors in the decision to diet among female adolescent students in Japan, applying the Theory of Planned Behavior. Data were collected from five junior high schools and three high schools in Naha City, Okinawa Prefecture, in 2010, through self-administered questionnaires. The data of 756 female students were assessed. The independent variables included social factor variables (norms) and personal factor variables (attitude to dieting, perceived behavior control, body esteem, body-figure discrepancy and past dieting). The dependent variables were dieting intention and behavior. Hierarchical multiple regression analyses were performed to examine three models: model 1 (age and obesity index), model 2 (social factor variables with age and obesity index) and model 3 (all variables). Although model 2 failed to explain a substantial proportion of the variance, model 3 explained approximately a half of the variance for intention (R2 = 0.507) and more than one third of the variance for behavior (R2 = 0.376). Past experience of dieting was the best predictor of both dieting intention and behavior. Body esteem was the second best predictor for dieting behavior. In conclusion, personal factors are more likely than social factors to drive the dieting decision. Diet education programs should consider targeting frequent dieters and those with poor body esteem.
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Affiliation(s)
- Khin Zay Yar Myint
- Department of Community and Global Health, Graduate School of Medicine, University of Tokyo , Hongo 7-3-1, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Daisuke Nonaka
- Department of Global Health, School of Health Sciences, University of the Ryukyus , Uehara 207, Nishihara-cho, Okinawa, 903-0215, Japan
| | - Masamine Jimba
- Department of Community and Global Health, Graduate School of Medicine, University of Tokyo , Hongo 7-3-1, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Keiko Nanishi
- Department of Community and Global Health, Graduate School of Medicine, University of Tokyo , Hongo 7-3-1, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Krishna Chandra Poudel
- Department of Health Promotion and Policy, School of Public Health and Health Sciences, University of Massachusetts Amherst , 316 Arnold House, 715 North Pleasant St, Amherst, MA 01003-9304, USA
| | - Junko Yasuoka
- Department of Community and Global Health, Graduate School of Medicine, University of Tokyo , Hongo 7-3-1, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Masaya Miyagi
- Faculty of Education, University of the Ryukyus , Senbaru 1, Nishihara-cho, Okinawa, 903-0213, Japan
| | - Masaki Shinjo
- Okinawa Prefectural College of Nursing , Yogi 1-24-1, Naha-shi, Okinawa, 902-8513, Japan
| | - Jun Kobayashi
- Department of Global Health, School of Health Sciences, University of the Ryukyus , Uehara 207, Nishihara-cho, Okinawa, 903-0215, Japan
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