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Search Results: 1 - 10 of 2948 matches for " Kwok-Fai Lam "
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Age, period, and cohort analysis of regular dental care behavior and edentulism: A marginal approach
Kar-Yan Li, May Wong, Kwok-Fai Lam, Eli Schwarz
BMC Oral Health , 2011, DOI: 10.1186/1472-6831-11-9
Abstract: Data from four sequential cross-sectional surveys of non-institutionalized Danes conducted from 1975-2005 comprising 4330 respondents aged 15+ years in 9 birth cohorts were analyzed. The key study variables were seeking dental care on an annual basis (ADC) and edentulism. For the analysis of ADC, survey year, age, gender, socio-economic status (SES) group, denture-wearing, and school dental care (SDC) during childhood were considered. For the analysis of edentulism, only respondents aged 35+ years were included. Survey year, age, gender, SES group, ADC, and SDC during childhood were considered as the independent factors. To take into account the clustering effect of birth cohorts, marginal logistic regressions with an independent correlation structure in generalized estimating equations (GEE) were carried out, with PROC GENMOD in SAS software.The overall proportion of people seeking ADC increased from 58.8% in 1975 to 86.7% in 2005, while for respondents aged 35 years or older, the overall prevalence of edentulism (35+ years) decreased from 36.4% in 1975 to 5.0% in 2005. Females, respondents in the higher SES group, in more recent survey years, with no denture, and receiving SDC in all grades during childhood were associated with higher probability of seeking ADC regularly (P < 0.05). The interaction of SDC and age (P < 0.0001) was significant. The probabilities of seeking ADC were even higher among subjects with SDC in all grades and aged 45 years or older. Females, older age group, respondents in earlier survey years, not seeking ADC, lower SES group, and not receiving SDC in all grades were associated with higher probability of being edentulous (P < 0.05).With the use of GEE, the potential clustering effect of birth cohorts in sequential cross-sectional oral health survey data could be appropriately considered. The success of Danish dental health policy was demonstrated by a continued increase of regular dental visiting habits and tooth retention in adults becaus
Influenza Polymerase Activity Correlates with the Strength of Interaction between Nucleoprotein and PB2 through the Host-Specific Residue K/E627
Andy Ka-Leung Ng, Wai-Hon Chan, Sze-Ting Choi, Mandy Ka-Han Lam, Kwok-Fai Lau, Paul Kay-Sheung Chan, Shannon Wing-Ngor Au, Ervin Fodor, Pang-Chui Shaw
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0036415
Abstract: The ribonucleoprotein (RNP) complex is the essential transcription-replication machinery of the influenza virus. It is composed of the trimeric polymerase (PA, PB1 and PB2), nucleoprotein (NP) and RNA. Elucidating the molecular mechanisms of RNP assembly is central to our understanding of the control of viral transcription and replication and the dependence of these processes on the host cell. In this report, we show, by RNP reconstitution assays and co-immunoprecipitation, that the interaction between NP and polymerase is crucial for the function of the RNP. The functional association of NP and polymerase involves the C-terminal ‘627’ domain of PB2 and it requires NP arginine-150 and either lysine-627 or arginine-630 of PB2. Using surface plasmon resonance, we demonstrate that the interaction between NP and PB2 takes place without the involvement of RNA. At 33, 37 and 41°C in mammalian cells, more positive charges at aa. 627 and 630 of PB2 lead to stronger NP-polymerase interaction, which directly correlates with the higher RNP activity. In conclusion, our study provides new information on the NP-PB2 interaction and shows that the strength of NP-polymerase interaction and the resulting RNP activity are promoted by the positive charges at aa. 627 and 630 of PB2.
Drug discovery from Chinese medicine against neurodegeneration in Alzheimer's and vascular dementia
Yuen-Shan Ho, Kwok-Fai So, Raymond Chang
Chinese Medicine , 2011, DOI: 10.1186/1749-8546-6-15
Abstract: Alzheimer's disease (AD) and vascular dementia (VaD) are the major forms of dementia. In addition, in the postmortem brains of the late stage of Parkinson's disease/Lewy body disease also find pathological hallmarks of AD [1]. Senile dementia is the progressive decline of memory and some related cognitive functions in the elderly. The global dementia population is predicted to reach 81.1 million by 2040 [2]. In 2010, the estimated prevalence of senile dementia in China is 6.0 to 7.0 million, accounting for about one-sixth of the global prevalence; the prevalence is expected to increase to 22.5 million by 2040, accounting for one-fourth of the global prevalence by that time [3]. The rapid increase in the number of dementia patients urgently demands effective prevention and treatment. Current approaches to dementia-related neurodegenerative diseases still highly rely on relieving symptoms. As some Chinese medicinal herbs have been used in treating dementia, many researchers are now turning to Chinese medicine for identifying potential neuroprotective agents or disease-modifying agent. This article reviews the strategy in the research of Chinese medicine in dementia related-neurodegenerative diseases.AD is clinically characterized by the progressive loss of memory, cognitive functions and behavioral changes. The pathogenesis of AD has been widely studied [4,5], in which beta-amyloid (Aβ) peptide and hyperphosphorylated tau protein as components of extracellular senile plaques and intracellular neurofibrillary tangles, respectively, are believed to be the targets for developing disease-modifying drugs. Current AD treatments are all symptom-relieving agents and heavily rely on the use of acetylcholinesterase (AChE) inhibitors (donepezil, rivastigmine and galantamine). AChE inhibitors slow down the degradation of the neurotransmitter acetylcholine, thereby increasing its bioavailability. Another approved AD treatment aims to reduce glutamate excitotoxicity. Memantine, the
Dendritic Morphology of Caudal Periaqueductal Gray Projecting Retinal Ganglion Cells in Mongolian Gerbil (Meriones unguiculatus)
Chaoran Ren, Mingliang Pu, Qi Cui, Kwok-Fai So
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0103306
Abstract: In this study we investigated the morphological features of the caudal periaqueductal gray (cPAG)-projecting retinal ganglion cells (RGCs) in Mongolian gerbils using retrograde labeling, in vitro intracellular injection, confocal microscopy and three-dimensional reconstruction approaches. cPAG-projecting RGCs exhibit small somata (10–17 μm) and irregular dendritic fields (201–298 μm). Sizes of somata and dendritic fields do not show obvious variation at different distance from the optic disk (eccentricity). Dendrites are moderately branched. Morphological analysis (n = 23) reveals that cPAG-projecting RGCs ramified in sublamina a and b in the inner plexiform layer. These cells exhibit different stratification patterns based on the thickness of dendritic bands in sublaminas a and b: majority of analyzed cells (16 out of 23) have two bands of arborizations share similar thickness. The rest of analyzed cells (7 out of 23) exhibit thinner band in sublamina a than in sublamina b. Together, the present study suggests that cPAG of Mongolian gerbil could receive direct retinal inputs from two types of bistratified RGCs. Furthermore, a small subset of melanopsin-expressing RGCs (total 41 in 6 animals) is shown to innervate the rostral PAG (rPAG). Functional characteristics of these non-visual center projecting RGCs remain to be determined.
GAP-43 expression correlates with spinal motoneuron regeneration following root avulsion
Qiuju Yuan, Bing Hu, Huanxing Su, Kwok-Fai So, Zhixiu Lin, Wutian Wu
Journal of Brachial Plexus and Peripheral Nerve Injury , 2009, DOI: 10.1186/1749-7221-4-18
Abstract: We have used immunohistochemistry to investigate the expression of GAP-43 in spinal motoneurons during nerve reconstruction following root avulsion in the neonatal and adult rats.Following the injury, GAP-43-immunoreactivity (IR) could be found in adult avulsed motoneurons as early as 1 day, increased from 3 to 7 days and reached a maximal level at 2 weeks post-injury. The up-regulation of GAP-43 in adult avulsed motoneurons was accompanied with the axonal regeneration indicated by numerous regenerating motor axons entering the reimplanted ventral root and nerve. In contrast, GAP-43-IR could not be found in the neonatal avulsed motoneurons at any examined post-injury time points. This failure of up-regulation of GAP-43 was coincident with no axonal regeneration in the reimplanted nerve in the neonatal rats.Close association of GAP-43 expression and capacity of regeneration in reimplanted spinal nerve of avulsed motoneurons suggests that GAP-43 is a potential therapeutic target for treatment of root avulsion of brachial plexus.The current treatment for brachial plexus root avulsion is mainly based on nerve transfers and nerve grafts directly implanted into the spinal cord. The results of brachial plexus reconstruction are poor, despite the sophistication of the various methods used [1]. In animals, nerve regeneration into a peripheral nerve (PN) graft after root avulsion was demonstrated in a series of experiments in rats, cats and primates [2-7]. We have previously shown that spinal motoneurons in adult rats can regenerate and reinnervate muscles to recover partial function [8-11]. However, avulsed motoneurons in neonatal rats are unable to regenerate into a PN graft [12], which indicates that intrinsic neuronal factors also determine the regenerative capabilities.Successfully regenerating neurons in mammalian peripheral nervous system (PNS) undergo a variety of changes in gene expression, for example, the prominent upregulation of growth-associated proteins [13,14]
Y-Like Retinal Ganglion Cells Innervate the Dorsal Raphe Nucleus in the Mongolian Gerbil (Meriones unguiculatus)
Liju Luan,Chaoran Ren,Benson Wui-Man Lau,Jian Yang,Gary E. Pickard,Kwok-Fai So,Mingliang Pu
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0018938
Abstract: The dorsal raphe nucleus (DRN) of the mesencephalon is a complex multi-functional and multi-transmitter nucleus involved in a wide range of behavioral and physiological processes. The DRN receives a direct input from the retina. However little is known regarding the type of retinal ganglion cell (RGC) that innervates the DRN. We examined morphological characteristics and physiological properties of these DRN projecting ganglion cells.
Development and validation of the Chinese Quality of Life Instrument
Kwok-fai Leung, Feng-bin Liu, Li Zhao, Ji-qian Fang, Kelvin Chan, Li-zhu Lin
Health and Quality of Life Outcomes , 2005, DOI: 10.1186/1477-7525-3-26
Abstract: The development of the ChQOL was based on the concept of health in Traditional Chinese Medicine with a theory driven approach. Based on the results of literature review, the research team developed an initial model of health which encompassed the concept of health in TCM. An expert panel was then invited to comment and give suggestions for improvement of the initial model. According to their suggestions, the model was refined and a set of initial items for the ChQOL was drafted. The refined model, together with the key domains, facets and initial items of the ChQOL were then mailed to a sample of about 100 Chinese medicine practitioners throughout Mainland China for their comments and advice. A revised set of items were developed for linguistic testing by a convenience sample consisting of both healthy people and people who attended Chinese Medicine treatment. After that, an item pool was developed for field-testing. Field test was conducted on a convenience sample of healthy and patient subjects to determine the construct validity and psychometric properties of the ChQOL.Construct validity was established by various methods, i.e. the internal consistency in all facets and domains were good; the correlation between facets to domain, and domains to overall ChQOL correlation were high; confirmatory factor analysis showed that the structure fitness of all facets, domain and overall structure were good with CFI > 0.9. Test-retest reliability was also good, especially in the domain scores with ICC value ranging from 0.83 to 0.90. No ceiling or floor effect was noted which indicated that ChQOL can be applied to subjects with a wide range of health status. Most facet scores, domain scores and the overall CHQOL scores were able to discriminate groups of subjects with known differences in health status. The ChQOL had mild positive convergence with the other generic health related QOL measures, i.e. the WHOQOL-100 and the SF-36, with moderate correlations.In conclusion, the s
Activation of the Nrf2/HO-1 Antioxidant Pathway Contributes to the Protective Effects of Lycium Barbarum Polysaccharides in the Rodent Retina after Ischemia-Reperfusion-Induced Damage
Meihua He, Hong Pan, Raymond Chuen-Chung Chang, Kwok-Fai So, Nicholas C. Brecha, Mingliang Pu
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0084800
Abstract: Lycium barbarum polysaccharides (LBP), extracts from the wolfberries, are protective to retina after ischemia-reperfusion (I/R). The antioxidant response element (ARE)–mediated antioxidant pathway plays an important role in maintaining the redox status of the retina. Heme oxygenase-1 (HO-1), combined with potent AREs in its promoter, is a highly effective therapeutic target for the protection against neurodegenerative diseases, including I/R-induced retinal damage. The aim of our present study was to investigate whether the protective effect of LBP after I/R damage was mediated via activation of the Nrf2/HO-1-antioxidant pathway in the retina. Retinal I/R was induced by an increase in intraocular pressure to 130 mm Hg for 60 minutes. Prior to the induction of ischemia, rats were orally treated with either vehicle (PBS) or LBP (1 mg/kg) once a day for 1 week. For specific experiments, zinc protoporphyrin (ZnPP, 20 mg/kg), an HO-1 inhibitor, was intraperitoneally administered at 24 h prior to ischemia. The protective effects of LBP were evaluated by quantifying ganglion cell and amacrine cell survival, and by measuring cell apoptosis in the retinal layers. In addition, HO-1 expression was examined using Western blotting and immunofluorescence analyses. Cytosolic and nuclear Nrf2 was measured using immunofluorescent staining. LBP treatment significantly increased Nrf2 nuclear accumulation and HO-1 expression in the retina after I/R injury. Increased apoptosis and a decrease in the number of viable cells were observed in the ganglion cell layer (GCL) and inner nuclear layer (INL) in the I/R retina, which were reversed by LBP treatment. The HO-1 inhibitor, ZnPP, diminished the LBP treatment-induced protective effects in the retina after I/R. Taken together, these results suggested that LBP partially exerted its beneficial neuroprotective effects via the activation of Nrf2 and an increase in HO-1 protein expression.
Effect of Lycium Barbarum (Wolfberry) Polysaccharides on Preserving Retinal Function after Partial Optic Nerve Transection
Patrick H. W. Chu, Hong-Ying Li, Man-Pan Chin, Kwok-fai So, Henry H. L. Chan
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0081339
Abstract: Lycium Barbarum Polysaccharides (LBP) are the active components of Wolfberry (a traditional Chinese medicine) which has long been used for improving visual function. This study aims to investigate localized changes of retinal function in a partial optic nerve transection (PONT) model, and effects of LBP on visual function. The multifocal electroretinograms (mfERG) were obtained from 30 eyes of 30 Sprague-Dawley rats. The rats were divided into 6 groups (five treatment groups and one control group). Starting from the first day of the experiment, the rats in the (PONT+LBP) group and the (LBP) group were dosed with LBP; rats in the (PONT+PBS (phosphate buffered saline)) group and the (PBS) group were dosed with PBS via nasogastric tube every day until euthanized. The dorsal part of the optic nerve was transected in the (PONT), (PONT+LBP) and (PONT+PBS) groups at the end of week 1 (day 7 after LBP or PBS feeding began). The mfERG was measured at three time points: week 2, week 3 and week 5. Significant reduction of P1 and PhNR amplitudes of the mfERG were observed in all retinal regions a week after PONT. Feeding with LBP prior to PONT preserved retinal function. All mfERG responses returned to the normal range in the superior retina, which corresponds to the transected dorsal region of the optic nerve, while most of the inferior retinal responses were significantly increased at week 4 after PONT. The ventral part of the retina had secondary degeneration which was not only limited to the ganglion cell layer, but is a widespread effect affecting the outer retina. LBP altered the functional reduction caused by PONT by regulating the signal from the outer retina.
Lycium Barbarum (Wolfberry) Reduces Secondary Degeneration and Oxidative Stress, and Inhibits JNK Pathway in Retina after Partial Optic Nerve Transection
Hongying Li, Yuxiang Liang, Kin Chiu, Qiuju Yuan, Bin Lin, Raymond Chuen-Chung Chang, Kwok-Fai So
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0068881
Abstract: Our group has shown that the polysaccharides extracted from Lycium barbarum (LBP) are neuroprotective for retinal ganglion cells (RGCs) in different animal models. Protecting RGCs from secondary degeneration is a promising direction for therapy in glaucoma management. The complete optic nerve transection (CONT) model can be used to study primary degeneration of RGCs, while the partial optic nerve transection (PONT) model can be used to study secondary degeneration of RGCs because primary degeneration of RGCs and secondary degeneration can be separated in location in the same retina in this model; in other situations, these types of degeneration can be difficult to distinguish. In order to examine which kind of degeneration LBP could delay, both CONT and PONT models were used in this study. Rats were fed with LBP or vehicle daily from 7 days before surgery until sacrifice at different time-points and the surviving numbers of RGCs were evaluated. The expression of several proteins related to inflammation, oxidative stress, and the c-jun N-terminal kinase (JNK) pathways were detected with Western-blot analysis. LBP did not delay primary degeneration of RGCs after either CONT or PONT, but it did delay secondary degeneration of RGCs after PONT. We found that LBP appeared to exert these protective effects by inhibiting oxidative stress and the JNK/c-jun pathway and by transiently increasing production of insulin-like growth factor-1 (IGF-1). This study suggests that LBP can delay secondary degeneration of RGCs and this effect may be linked to inhibition of oxidative stress and the JNK/c-jun pathway in the retina.
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