318 results on '"Chiba, Takeshi"'
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302. Quintessence Cosmology and Varying {alpha}
- Author
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Chiba, Takeshi and Kohri, Kazunori
- Abstract
If the reported measurements of the time variation of the fine structure constant from observations of distant QSOs are correct, combined with the Oklo limit, they would strongly constrain the class of the quintessence potential. If these results prove valid, future satellite experiments (STEP) should measure the induced violation of the weak equivalence principle. Future cosmological observations of nearby (z ≲ 0.5) absorption systems would make it clear whether the variation is significant or not.
- Published
- 2002
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303. Lens Model Degeneracy and Cosmological Tests by Strong Gravitational Lensing
- Author
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Chiba, Takeshi and Takahashi, Ryuichi
- Abstract
We estimate the sensitivity of lensing observables to the parameters in the lens model (isothermal sphere/Navarro-Frenk-White profile) parameters and to cosmological parameters. We find that the observables are primarily dependent on the lens model parameters, while the dependence on cosmological parameters is minor (especially so for the dark energy parameters). We demonstrate the lens model degeneracy by deriving both the projected mass density profile and the circular velocity profile. We also identify a possible source of the problem of fitting the averaged mass profile of CL 0024+1654 with the Navarro-Frenk-White profile.
- Published
- 2002
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304. Cylindrical Dust Collapse in General Relativity: Toward Higher Dimensional Collapse
- Author
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Chiba, Takeshi
- Abstract
Motivated by possible spindle naked singularity formation in prolate collapse, we investigate the dust collapse in cylindrically symmetric spacetime. First, possible singularity avoidance property of the maximal time slicing in cylindrically symmetric spacetime is investigated. It is found both analytically and numerically that the maximal time slicing never has that property and that the lapse function decreases only slowly and hits a singularity in cylindrically symmetric spacetime. We propose a new kind of time slice which may be suitable to investigate the formation of a cylindrical singularity. Second taking into account these results, dust collapse is investigated numerically in order to see the role of gravitational waves during the gravitational collapse leading to a naked singularity. We find negligible gravitational wave emission during the free fall time. This is consistent with Shapiro-Teukolsky claim that neglibible gravitational waves are emitted in prolate collapse of collisionless particles. The implications of these results for axisymmetric collapse, especially for prolate collapse, are also discussed.
- Published
- 1996
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305. The Minimum Mass of the First Stars and the Anthropic Pinciple
- Author
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Nakamura, Takashi, Uehara, Hideya, and Chiba, Takeshi
- Abstract
The lower limit of the mass of the first stars suggested recently may imply the formation of massive stars of mass greater than 8M
⊙ irrespective of the details of the initial mass function. The production of heavy metals from the first stars will provide a requisite for the existence of life without the anthropic principle.- Published
- 1997
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306. Dynamic postural control correlates with activities of daily living and quality of life in patients with knee osteoarthritis.
- Author
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Sabashi, Kento, Ishida, Tomoya, Matsumoto, Hisashi, Mikami, Kentaro, Chiba, Takeshi, Yamanaka, Masanori, Aoki, Yoshimitsu, and Tohyama, Harukazu
- Subjects
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QUALITY of life , *ACTIVITIES of daily living , *KNEE , *OSTEOARTHRITIS - Abstract
Background: Knee osteoarthritis (OA) negatively affects dynamic postural control, which is a basic function that individuals use to perform activities of daily living (ADL). The purpose of this study was to investigate the associations of center of pressure (COP) control during the transition from double-leg to single-leg standing with subjective assessments of ADL and quality of life (QOL) in patients with knee OA.Methods: Thirty-six patients (29 females) with moderate-to-severe knee OA participated. Dynamic postural control was evaluated during the transition from double-leg to single-leg standing. Each patient stood on a force plate, lifted the less affected limb as fast as possible, and maintained single-leg standing with the more affected limb. The COP movements corresponding to anticipatory postural adjustment (APA) and transitional phases were assessed. The maximum displacement and peak velocity of the COP movements in the medial-lateral direction were calculated. The Knee Injury and Osteoarthritis Outcome Score (KOOS) was used for the subjective assessment of ADL and QOL. Pearson's product correlation analysis was performed to investigate the associations of COP movements in the APA and transitional phases with KOOS-ADL and KOOS-QOL.Results: In the APA phase, the maximum COP displacement was significantly correlated with KOOS-ADL (r = -0.353, P = 0.035) and KOOS-QOL (r = -0.379, P = 0.023). In the transitional phase, the maximum COP displacement and peak COP velocity were significantly correlated with KOOS-ADL (maximum displacement: r = 0.352, P = 0.035; peak velocity: r = 0.438, P = 0.008) and with KOOS-QOL (maximum displacement: r = 0.357, P = 0.032; peak velocity: r = 0.343, P = 0.040).Conclusions: The present study showed that smaller COP movements in the APA phase and smaller and slower COP movements in the transitional phase correlated with poorer ADL and QOL conditions in patients with knee OA. These findings suggest that poor dynamic postural control is associated with poor ADL and QOL conditions in patients with moderate-to-severe medial knee OA. Conservative treatment for patients with knee OA may need to focus on dynamic postural control during the transition from double-leg to single-leg standing. [ABSTRACT FROM AUTHOR]- Published
- 2021
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307. Abdominal draw-in maneuver changes neuromuscular responses to sudden release from trunk loading in patients with non-specific chronic low back pain.
- Author
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Osuka, Satoshi, Ishida, Tomoya, Yamanaka, Masanori, Chiba, Takeshi, Miura, Takuya, Koshino, Yuta, Saito, Yuki, Nakata, Akimi, Samukawa, Mina, Kasahara, Satoshi, and Tohyama, Harukazu
- Subjects
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LUMBAR pain , *MUSCLES , *SKELETAL muscle physiology , *MUSCLE contraction , *ABDOMINAL muscles , *ELECTROMYOGRAPHY , *KINEMATICS - Abstract
Background: Abdominal draw-in maneuver (ADIM) has been recommended to achieve appropriate trunk muscle response for patients with non-specific chronic low back pain (CLBP). However, it has remained unclear whether the intervention with ADIM could change the trunk muscle response to sudden release from loading, which is considered to contribute mechanical circumstances to low back pain. The purpose of the present study was to investigate the effects of the intervention with ADIM on electromyography (EMG) activities of trunk muscles following sudden release from loading.Methods: Seventeen subjects with non-specific CLBP participated. Subjects resisted trunk flexion or extension loading in semi-seated position, and then the loading was suddenly released. EMG recordings of 6 trunk muscles were acquired using a wireless surface EMG system. Onset and offset times were calculated from the EMG data. The intervention with ADIM was provided for 4 weeks. The onset and offset times were compared between pre- and post-intervention with ADIM.Results: At the post-intervention, the onset of trunk flexors following release from trunk flexion loading became significantly earlier than pre-intervention (P = 0.028). The offset of flexors following release from trunk extension loading of post-intervention was significantly earlier than that of pre-intervention (P = 0.001).Conclusions: We showed that the intervention with ADIM changed the EMG activity of trunk flexors in response to sudden release from loading. These results suggest a possibility that ADIM might be effective to improve the neuromuscular control of trunk flexors for the treatment of young patients with non-specific CLBP. [ABSTRACT FROM AUTHOR]- Published
- 2020
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308. Equation of state of tracker fields
- Author
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Chiba, Takeshi [Department of Physics, College of Humanities and Sciences, Nihon University, Tokyo 156-8550 (Japan)]
- Published
- 2010
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309. Erratum: w and w{sup '} of scalar field models of dark energy [Phys. Rev. D 73, 063501 (2006)]
- Author
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Chiba, Takeshi
- Published
- 2009
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310. Erratum: Slow-roll thawing quintessence [Phys. Rev. D 79, 083517 (2009)]
- Author
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Chiba, Takeshi
- Published
- 2009
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311. Slow-roll thawing quintessence
- Author
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Chiba, Takeshi [Department of Physics, College of Humanities and Sciences, Nihon University, Tokyo 156-8550 (Japan)]
- Published
- 2009
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312. Smoking-induced suppression of β-casein in milk is associated with an increase in miR-210-5p expression in mammary epithelia.
- Author
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Chiba T, Takaguri A, Mikuma T, Kimura T, and Maeda T
- Abstract
Smoking during lactation harmfully affects the amount and constituents of breast milk. Infants who consume breast milk containing miR-210-5p may have a higher risk of brain-related diseases. We investigated whether smoking during lactation decreases β-casein concentrations in milk and whether miR-210-5p expression is involved in smoking-induced β-casein suppression. During lactation, maternal CD1 mice were exposed to cigarette smoke (1.7 mg of tar and 14 mg of nicotine) in a smoke chamber for 1 h twice/day for five consecutive days. Control mice were placed in an air-filled chamber equivalent in size to the smoke chamber, with maternal separation times identical to those of the smoked mice. Maternal exposure to smoke during lactation significantly decreased β-casein expression in the mammary epithelia of smoked mice compared to that of the control mice. Signal transducer and activator transcription 5 (STAT5) and phosphorylated STAT5 (pSTAT5) are transcription factors involved in β-casein expression. In the mammary epithelia of smoked mice, the pSTAT5 and STAT5 levels were significantly lower, and miR-210-5p expression was significantly higher than that of the control mice. The β-casein, pSTAT5, and STAT5 protein levels of miR-210-5p mimic-transfected human mammary epithelial MCF-12A cells were significantly lower than those of control siRNA-transfected cells. These results indicate that smoke exposure led to an increase in miR-210-5p expression in mammary epithelium and a decrease in pSTAT5 and β-casein protein levels through the inhibition of STAT5 expression. Moreover, nicotine treatment decreased β-casein protein levels and increased miR-210-5p expression in non-malignant human mammary epithelial MCF-12A cells in a concentration-dependent manner, demonstrating that nicotine significantly affects the β-casein and miR-210-5p levels of breast milk. These results highlight the adverse effects of smoking on breast milk, providing essential information for healthcare professionals and general citizens., Competing Interests: The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Takeshi Chiba reports financial support was provided by Japanese Society for the Promotion of Science. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors.)
- Published
- 2024
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313. Effect of toe-out gait modification on patellofemoral joint loading.
- Author
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Sabashi K, Chiba T, Yamanaka M, and Tohyama H
- Subjects
- Adult, Humans, Biomechanical Phenomena, Gait, Knee Joint, Toes, Patellofemoral Joint, Osteoarthritis, Knee
- Abstract
Background: Toe-out gait has been proposed as a conservative treatment to reduce medial tibiofemoral joint loading. However, patellofemoral joint loading during toe-out gait is not yet understood., Research Question: Does the toe-out gait modification affect patellofemoral joint loading?, Methods: Sixteen healthy adults were enrolled in this study. The natural gait and toe-out gait were measured using a three-dimensional motion analysis and a force plate. The knee flexion angle and external knee flexion moment during the stance phase were calculated. Thus, dynamic knee joint stiffness, a proxy of patellofemoral joint loading, was defined as a linear regression of the knee flexion moment and knee flexion angle during the early stance. Additionally, the peak patellofemoral compressive force during the early stance was calculated using a musculoskeletal simulation. A paired t-test was used to compare these biomechanical parameters during the natural gait and toe-out gait., Results: The toe-out gait significantly increased the peak patellofemoral compressive force (mean difference = 0.37 BW, P = 0.017) and dynamic knee joint stiffness (mean difference = 0.07%BW*Ht/°, P = 0.001). The 1st peak of the knee flexion moment also significantly increased in the toe-out gait (mean difference = 1.01%BW*Ht, P = 0.003); however, the knee flexion angle did not change significantly (initial contact: mean difference = 1.7°, P = 0.078; peak: mean difference = 1.3°, P = 0.224)., Significance: Toe-out gait increased the patellofemoral compressive force and dynamic knee joint stiffness because of increasing knee flexion moment, but not the knee flexion angle. When the toe-out gait is adapted, clinicians should pay attention to an increase in the patellofemoral joint loading., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)
- Published
- 2023
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314. Early Changes in Postural Balance Following Inverted V-Shaped High Tibial Osteotomy in Patients With Knee Osteoarthritis.
- Author
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Sabashi K, Chiba T, Iwasaki K, Onodera T, Kondo E, Iwasaki N, and Tohyama H
- Subjects
- Humans, Tibia surgery, Knee Joint surgery, Pain etiology, Osteotomy adverse effects, Osteotomy methods, Postural Balance, Osteoarthritis, Knee surgery, Osteoarthritis, Knee etiology
- Abstract
Patients with knee osteoarthritis and varus knee deformity have impaired postural balance, resulting in decreased walking performance and an increased risk of falls. This study aimed to investigate the early changes in the postural balance following inverted V-shaped high tibial osteotomy (HTO). Fifteen patients with medial knee osteoarthritis were recruited. Postural balance was assessed using the center-of-pressure (COP) data during single-leg standing before and 6 weeks after inverted V-shaped HTO. The maximum range, mean velocity, and area of COP movements in the anteroposterior and mediolateral directions were analyzed. Preoperative and postoperative visual analog scale for knee pain was assessed. The maximum range of COP in the mediolateral direction decreased (P = .017), whereas the mean velocity of COP in the anteroposterior direction increased 6 weeks postoperatively (P = .011). The visual analog scale score for knee pain significantly improved at 6 weeks postoperatively (P = .006). Valgus correction with inverted V-shaped HTO resulted in improved postural balance in the mediolateral direction and good short-term clinical outcomes early following surgery. Early rehabilitation after inverted V-shaped HTO should focus on postural balance in the anteroposterior direction.
- Published
- 2023
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315. Human Milk Exosomes Induce ZO-1 Expression via Inhibition of REDD1 Expression in Human Intestinal Epithelial Cells.
- Author
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Chiba T and Maeda T
- Subjects
- Humans, Intestinal Mucosa metabolism, Caco-2 Cells, Milk, Human metabolism, Intestines, Epithelial Cells, TOR Serine-Threonine Kinases metabolism, Zonula Occludens-1 Protein genetics, Zonula Occludens-1 Protein metabolism, Tight Junctions metabolism, Exosomes metabolism
- Abstract
Human milk exosomes (HMEs) enhance intestinal barrier function and contribute to an improvement in inflammation and mucosal injury, such as necrotizing enteritis (NEC), in infants. Here, we aimed to elucidate the intracellular factors involved in HME-induced expression of zonula occludens-1 (ZO-1), a tight junction protein, in Caco-2 human intestinal epithelial cells. HME treatment for 72 h significantly increased transepithelial electrical resistance in these cells. The mean ZO-1 protein levels in cells treated with HME for 72 h were significantly higher than those in the control cells. The mRNA and protein levels of regulated in development and DNA damage response 1 (REDD1) in HME-treated cells were significantly lower than those in the control cells. Although HME treatment did not increase the mechanistic target of rapamycin (mTOR) level in Caco-2 cells, it significantly increased the phosphorylated mTOR (p-mTOR) level and p-mTOR/mTOR ratio. The ZO-1 protein levels in cells treated with an inducer of REDD1, cobalt chloride (CoCl
2 ) alone were significantly lower than those in the control cells. However, ZO-1 protein levels in cells co-treated with HME and CoCl2 were significantly higher than those in cells treated with CoCl2 alone. Additionally, REDD1 protein levels in cells treated with CoCl2 alone were significantly higher than those in the control cells. However, REDD1 protein levels in cells co-treated with HME and CoCl2 were significantly lower than those in cells treated with CoCl2 alone. This HME-mediated effect may contribute to the development of barrier function in the infant intestine and protect infants from diseases.- Published
- 2023
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316. Suppression of milk-derived miR-148a caused by stress plays a role in the decrease in intestinal ZO-1 expression in infants.
- Author
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Chiba T, Takaguri A, Kooka A, Kowatari K, Yoshizawa M, Fukushi Y, Hongo F, Sato H, Fujisawa M, Wada S, and Maeda T
- Subjects
- Adult, Animals, Female, Humans, Infant, Mice, Pregnancy, Caco-2 Cells, Intestines, Milk, Human, MicroRNAs genetics, Tight Junctions metabolism
- Abstract
Background & Aims: Milk-derived miR-148a-3p (miR-148a), which is abundant in breast milk, has been shown to be associated with the development of infants' intestines. Although it is well known that stress during lactation changes milk constituents in terms of lipid and protein, no studies have examined the influence of stress on miR-148a expression in breast milk. The objective of this study is to investigate the relationship between stress and miR-148a expression in milk, and to evaluate whether the changes in milk-derived miR-148a expression-caused by the mother's exposure to stress-influence intestinal ZO-1 expression in infants., Methods: The participants of this study were healthy Japanese women who were nursing. Psychological stress evaluation of the subjects was conducted using a short form of the Profile of Mood State Second Edition-Adult (POMS-2). Additionally, miR-148a expressions in restraint stressed nursing mice were investigated using quantitative real-time PCR. The levels of a tight junction protein zonula occludens-1 (ZO-1) and DNA methyltransferase 1 (DNMT1), which is a direct target of miR-148a, in ileum in neonatal mice breastfed by stressed nursing mice were investigated using Western blot. Furthermore, to investigate the influence of miR-148a on ZO-1 expression within the intestine, the levels of ZO-1 and DNMT1 in human intestinal epithelial Caco-2 cells with lentivirus-mediated miR-148a overexpression were evaluated., Results: A significantly negative correlation was observed between relative miR-148a expression in breast milk and the total mood disturbance T-score. Each T-score on negative mood subscales of anger-hostility, confusion-bewilderment, depression-dejection, fatigue-inertia, and tension-anxiety was significantly negatively correlated with relative miR-148a expression in breast milk: a positive mood subscale vigor-activity T-score was significantly positively correlated with relative miR-148a expression in breast milk. A positive mood friendliness T-score, estimated separately from other scores, was significantly positively correlated with relative miR-148a expression in breast milk. Additionally, the relative expression of miR-148a in the milk obtained from stressed mice was significantly lower than that of control mice. The relative level of ZO-1 in ileum of neonatal mice nursed by stressed mice was significantly lower than that of neonatal mice nursed by control mice. Additionally, the relative level of DNMT1 in ileum of neonatal mice nursed by stressed mice was significantly higher than that of neonatal mice nursed by control mice. Furthermore, the relative level of ZO-1 in miR-148a-overexpressed Caco-2 cells was significantly higher than that in control cells. The relative level of DNMT1 in miR-148a-overexpressed Caco-2 cells was significantly lower than that in control cells., Conclusions: Mothers' exposure to stress during lactation may cause miR-148a expression in breast milk. Additionally, stressed-induced suppression of miR-148a expression in breast milk may cause a decrease in intestinal ZO-1 level via the increase in DNMT1 in infants' intestines. These observations are beneficial information for breastfeeding mothers and their families and perinatal medical professionals. Our findings encourage monitoring maternal psychological stress during lactation to promote breastfeeding and adequate infant nutrition., (Copyright © 2022 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.)
- Published
- 2022
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317. Expression profiles of hsa-miR-148a-3p and hsa-miR-125b-5p in human breast milk and infant formulae.
- Author
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Chiba T, Kooka A, Kowatari K, Yoshizawa M, Chiba N, Takaguri A, Fukushi Y, Hongo F, Sato H, and Wada S
- Subjects
- Breast Feeding, Cesarean Section, Female, Humans, Lactation, Pregnancy, MicroRNAs genetics, Milk, Human
- Abstract
Background: Milk-derived microRNAs (miRNAs), including hsa-miR-148a-3p (miR-148a) and hsa-miR-125b-5p (miR-125b), have been shown to be beneficial to the gastrointestinal function in infants. Here, we investigated their expression during lactation in humans and determined whether the infant formulae available in Japan contain these miRNAs., Methods: Healthy Japanese women (n = 16) who gave birth vaginally or by cesarean section at the Teine Keijinkai Hospital between 1 September 2020, and 31 April 2021 were included in this study. Breast milk was collected by nurses on days 4 or 5 after delivery (hereinafter, transition milk) and on day 30 of postpartum (hereinafter, mature milk). The levels of miR-148a and miR-125b in breastmilk and six commercially available infant formulae were compared and evaluated using quantitative reverse transcription-polymerase chain reaction., Results: In all participants, the miR-148a level in mature breastmilk was significantly lower than that in the transition milk. The changes in miR-125b expression during lactation showed similar trends to the changes in miR-148a expression. The miR-148a and miR-125b levels in all analyzed infant formulae were lower than 1/500th and 1/100th of those in mature breastmilk, respectively., Conclusions: The levels of both miR-148a and miR-125b in human breast milk decreased on day 30 postpartum compared with those in the transition milk. Additionally, the expression of these miRNAs in infant formulae available in Japan was very low. Further studies with larger populations are required to understand precisely the lactational changes in the expression of miR148a and miR-125b in breast milk., (© 2021. The Author(s).)
- Published
- 2022
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318. [DEVELOPMENT OF MEDICAL EDUCATIONAL PROGRAM FOR PEDIATRICIANS TO IMPROVE THEIR BEHAVIOR IN THE MANAGEMENT OF FOOD ALLERGY].
- Author
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Tsumura Y, Yomase M, Chiba T, Narita M, Futamura M, and Ohya Y
- Subjects
- Allergens immunology, Behavior, Child, Dermatitis, Atopic therapy, Health Knowledge, Attitudes, Practice, Humans, Physician's Role, Education, Medical, Continuing, Food Hypersensitivity therapy
- Abstract
Background: Many children are suffering from food allergy, however, not all of them are treated properly by pediatricians based on the latest practice guideline. The guideline does not recommend excessive elimination diet, but suggests initial appropriate skincare treatment before examining candidate allergens for food-allergy-patients with atopic dermatitis. We developed and evaluated a curriculum for continuing medical education for pediatrician about food allergy., Methods: We provided a medical educational program for pediatricians at the Division of Allergy in National Center for Child Health and Development, from January 2013 to January 2014. The program was aimed to improve their behavior in the management of food allergy, if they excessively eliminated diet from the patients and did not treat atopic dermatitis appropriately. The program was constituted of SBOs and educational strategy. Participant's self evaluation of learning and that of behavior were carried out before and after the training, and their scores were analyzed for the program evaluation., Results: Thirty-five participants completed the program. All the scores rating 22 items for evaluation of learning were increased. Five items out of 7 about evaluation of behavior were significantly improved., Conclusion: We developed a medical educational program about food allergy for pediatricians. After training based on this program, the participants' knowledge and skills were improved and their behavior was desirably modified.
- Published
- 2015
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