http://hdl.handle.net/10397/1721 Search the Channel search http://repository.lib.polyu.edu.hk/jspui/simple-search http://hdl.handle.net/10397/5298 Title: Dynamic expression of Dab2 in the mouse embryonic central nervous system<br/><br/>Authors: Cheung, Alex K. K.; Mok, Samuel C.; Rezaie, Payam; Chan, Wood Yee<br/><br/>Abstract: Background: Dab2, one of two mammalian orthologs of Drosophila Disabled, has been shown to be involved in cell positioning and formation of visceral endoderm during mouse embryogenesis, but its role in neuronal development is not yet fully understood. In this report, we have examined the localization of the Dab2 protein in the mouse embryonic central nervous system (CNS) at different developmental stages.; Results: Dab2 protein was transiently expressed in rhombomeres 5 and 6 of the developing hindbrain between E8.5 and E11.5, and in the floor plate of the neural tube from E9.5 to E12.5, following which it was no longer detectable within these regions. Dab2 protein was also identified within circumventricular organs including the choroid plexus, subcommissural organ and pineal gland during their early development. While Dab2 was still strongly expressed in the adult choroid plexus, immunoreactivity within the subcommissural organ and pineal gland was lost after birth. In addition, Dab2 was transiently expressed within a subpopulation of Iba1-positive mononuclear phagocytes (including presumed microglial progenitors) within the neural tube from E10.0 and was lost by E14.5. Dab2 was separately localized to Iba1 positive cells from E9.5 and subsequently to F4/80 positive cells (mature macrophage/myeloid-derived dendritic cells) positioned outside the neural tube from E12.5 onwards, implicating Dab2 expression in early cells of the mononuclear phagocyte lineage. Dab2 did not co-localize with the pan-neuronal marker PGP9.5 at any developmental stage, suggesting that Dab2 positive cells in the developing CNS are unlikely to be differentiating neurons.; Conclusion: This is the first study to demonstrate the dynamic spatiotemporal expression of Dab2 protein within the CNS during development.<br/><br/>Description: DOI: 10.1186/1471-213X-8-76 http://hdl.handle.net/10397/5296 Title: The association between back pain and trunk posture of workers in a special school for the severe handicaps<br/><br/>Authors: Wong, Kelvin C. H.; Lee, Yun-wah Raymond; Yeung, Sai-mo Simon<br/><br/>Abstract: Background: The present study aims to determine the time spent in different static trunk postures during a typical working day of workers in a special school for the severe handicaps.; Methods: Eighteen workers with low back pain (LBP) and fifteen asymptomatic workers were recruited. A cross-sectional design was employed to study the time spent in different static trunk postures which was recorded by a biaxial accelerometer attached to the T12 level of the back of the subjects.; Results: The results of ANCOVA revealed that subjects with LBP spent significantly longer percentage of time in static trunk posture when compared to normal (p < 0.05). It was also shown that they spent significantly longer time in trunk flexion for more than 10° (p < 0.0125).; Conclusion: An innovative method has been developed for continuous tracking of spinal posture, and this has potential for widespread applications in the workplace. The findings of the present investigation suggest that teachers in special schools are at increased risk of getting LBP. In order to minimise such risk, frequent postural change and awareness of work posture are recommended.<br/><br/>Description: DOI: 10.1186/1471-2474-10-43 http://hdl.handle.net/10397/4846 Title: Electrical stimulation influences satellite cell proliferation and apoptosis in unloading-induced muscle atrophy in mice<br/><br/>Authors: Guo, Bao-Sheng; Cheung, Alex K. K.; Yeung, Sai-mo Simon; Zhang, Bao-Ting; Yeung, Wai Ella<br/><br/>Abstract: Muscle atrophy caused by disuse is accompanied by adverse physiological and functional consequences. Satellite cells are the primary source of skeletal muscle regeneration. Satellite cell dysfunction, as a result of impaired proliferative potential and/or increased apoptosis, is thought to be one of the causes contributing to the decreased muscle regeneration capacity in atrophy. We have previously shown that electrical stimulation improved satellite cell dysfunction. Here we test whether electrical stimulation can also enhance satellite cell proliferative potential as well as suppress apoptotic cell death in disuse-induced muscle atrophy. Eight-week-old male BALB/c mice were subjected to a 14-day hindlimb unloading procedure. During that period, one limb (HU-ES) received electrical stimulation (frequency: 20 Hz; duration: 3 h, twice daily) while the contralateral limb served as control (HU). Immunohistochemistry and western blotting techniques were used to characterize specific proteins in cell proliferation and apoptosis. The HU-ES soleus muscles showed significant improvement in muscle mass, cross-sectional area, and peak tetanic force relative to the HU limb (p<0.05). The satellite cell proliferative activity as detected within the BrdU⁺/Pax7⁺ population was significantly higher (p<0.05). The apoptotic myonuclei (detected by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling) and the apoptotic satellite cells (detected by cleaved Poly [ADP-ribose] polymerase co-labeled with Pax7) were reduced (p<0.05) in the HU-ES limb. Furthermore the apoptosis-inducing factor and cleaved caspase-3 were down-regulated while the anti-apoptotic Bcl-2 protein was up-regulated (p<0.05), in the HU-ES limb. These findings suggest that the electrical stimulation paradigm provides an effective stimulus to rescue the loss of myonuclei and satellite cells in disuse muscle atrophy, thus maintaining a viable satellite cell pool for subsequent muscle regeneration. Optimization of stimulation parameters may enhance the outcome of the intervention.<br/><br/>Description: DOI: 10.1371/journal.pone.0030348 http://hdl.handle.net/10397/4840 Title: Positive youth development programs: experience based on the Project P.A.T.H.S. in Hong Kong = 「共創成長路」青少年正面成長課程在香港推行的經驗<br/><br/>Authors: Shek, Daniel T. L.; Siu, M. H. Andrew<br/><br/>Abstract: A survey of the literature shows that there are worrying trends and phenomena related to the development of adolescents in Hong Kong. As such, primary prevention programs targeting specific adolescent developmental problems and positive youth development programs are called for. However, research findings show that there are very few systematic and multi-year positive youth development programs in Hong Kong. In response to this worrying picture, a positive youth development program entitled Project P.A. THS. was initiated by The Hong Kong Jockey Club Charities Trust to promote holistic development of junior secondary school students in Hong Kong, with the involvement of five universities in Hong Kong the program development, training and evaluation. Based on different evaluation strategies, existing research findings generally revealed that different stakeholders had positive perceptions of the program, workers. as well as benefits the program and the program was effective in promoting holistic positive youth development in Chinese adolescents in Hong Kong.; 在近年，多項本地調查顯示，香港青少年的發展有多個令人擔憂的現象及趨勢。社會有需要發展基層健康方案，以針對年青人的發展問題及培育正面發展。可是，香港多年來都未有開發有系統及持續的青少年正面成長課程。針對這令人擔憂的現象，香港賽馬會結善信託基金贊助及椎動了一個名為「共創成長路」的青少年正面成長課程，以促進香港初中學生的全面發展。「共創成長路」計劃的課程由本地五所大學所設計、並進行導師培訓及成效評估。通過使用不同的評估策略，成效研究結果顯示，不同的利益相關者普遍對計劃、導師、及效益有正面的評價，認為「共創成長路」的課程能有效地促進香港青少年的正面發展。