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Search Results: 1 - 10 of 10881 matches for " Chi Bun Chan "
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Multiple Functions of Phosphoinositide-3 Kinase Enhancer (PIKE)
Chi Bun Chan,Keqiang Ye
The Scientific World Journal , 2010, DOI: 10.1100/tsw.2010.64
Abstract:
Lectins with Anti-HIV Activity: A Review
Ouafae Akkouh,Tzi Bun Ng,Senjam Sunil Singh,Cuiming Yin,Xiuli Dan,Yau Sang Chan,Wenliang Pan,Randy Chi Fai Cheung
Molecules , 2015, DOI: 10.3390/molecules20010648
Abstract: Lectins including flowering plant lectins, algal lectins, cyanobacterial lectins, actinomycete lectin, worm lectins , and the nonpeptidic lectin mimics pradimicins and benanomicins, exhibit anti-HIV activity. The anti-HIV plant lectins include Artocarpus heterophyllus (jacalin) lectin, concanavalin A, Galanthus nivalis (snowdrop) agglutinin-related lectins, Musa acuminata (banana) lectin, Myrianthus holstii lectin, Narcissus pseudonarcissus lectin, and Urtica diocia agglutinin. The anti-HIV algal lectins comprise Boodlea coacta lectin, Griffithsin, Oscillatoria agardhii agglutinin. The anti-HIV cyanobacterial lectins are cyanovirin- N, scytovirin, Microcystis viridis lectin , and microvirin. Actinohivin is an anti-HIV actinomycete lectin. The anti-HIV worm lectins include Chaetopterus variopedatus polychaete marine worm lectin, Serpula vermicularis sea worm lectin, and C-type lectin Mermaid from nematode ( Laxus oneistus) . The anti-HIV nonpeptidic lectin mimics comprise pradimicins and benanomicins. Their anti-HIV mechanisms are discussed.
Embryonic Lethality in Mice Lacking the Nuclear Factor of Activated T Cells 5 Protein Due to Impaired Cardiac Development and Function
Man Chi Mak, Ka Man Lam, Ping Kei Chan, Yu Bond Lau, Wai Ho Tang, Patrick Ka Kit Yeung, Ben Chi Bun Ko, Stephen Man Sum Chung, Sookja Kim Chung
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0019186
Abstract: Nuclear factor of activated T cells 5 protein (NFAT5) is thought to be important for cellular adaptation to osmotic stress by regulating the transcription of genes responsible for the synthesis or transport of organic osmolytes. It is also thought to play a role in immune function, myogenesis and cancer invasion. To better understand the function of NFAT5, we developed NFAT5 gene knockout mice. Homozygous NFAT5 null (NFAT5?/?) mouse embryos failed to develop normally and died after 14.5 days of embryonic development (E14.5). The embryos showed peripheral edema, and abnormal heart development as indicated by thinner ventricular wall and reduced cell density at the compact and trabecular areas of myocardium. This is associated with reduced level of proliferating cell nuclear antigen and increased caspase-3 in these tissues. Cardiomyocytes from E14.5 NFAT5?/? embryos showed a significant reduction of beating rate and abnormal Ca2+ signaling profile as a consequence of reduced sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA) and ryanodine receptor (RyR) expressions. Expression of NFAT5 target genes, such as HSP 70 and SMIT were reduced in NFAT5?/? cardiomyocytes. Our findings demonstrated an essential role of NFAT5 in cardiac development and Ca2+ signaling. Cardiac failure is most likely responsible for the peripheral edema and death of NFAT5?/? embryos at E14.5 days.
Trichosanthin Inhibits Breast Cancer Cell Proliferation in Both Cell Lines and Nude Mice by Promotion of Apoptosis
Evandro Fei Fang, Chris Zhi Yi Zhang, Lin Zhang, Jack Ho Wong, Yau Sang Chan, Wen Liang Pan, Xiu Li Dan, Cui Ming Yin, Chi Hin Cho, Tzi Bun Ng
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0041592
Abstract: Breast cancer ranks as a common and severe neoplasia in women with increasing incidence as well as high risk of metastasis and relapse. Translational and laboratory-based clinical investigations of new/novel drugs are in progress. Medicinal plants are rich sources of biologically active natural products for drug development. The 27-kDa trichosanthin (TCS) is a ribosome inactivating protein purified from tubers of the Chinese herbal plant Trichosanthes kirilowii Maximowicz (common name Tian Hua Fen). In this study, we extended the potential medicinal applications of TCS from HIV, ferticide, hydatidiform moles, invasive moles, to breast cancer. We found that TCS manifested anti-proliferative and apoptosis-inducing activities in both estrogen-dependent human MCF-7 cells and estrogen-independent MDA-MB-231 cells. Flow cytometric analysis disclosed that TCS induced cell cycle arrest. Further studies revealed that TCS-induced tumor cell apoptosis was attributed to activation of both caspase-8 and caspase-9 regulated pathways. The subsequent events including caspase-3 activation, and increased PARP cleavage. With regard to cell morphology, stereotypical apoptotic features were observed. Moreover, in comparison with control, TCS- treated nude mice bearing MDA-MB-231 xenograft tumors exhibited significantly reduced tumor volume and tumor weight, due to the potent effect of TCS on tumor cell apoptosis as determined by the increase of caspase-3 activation, PARP cleavage, and DNA fragmentation using immunohistochemistry. Considering the clinical efficacy and relative safety of TCS on other human diseases, this work opens up new therapeutic avenues for patients with estrogen-dependent and/or estrogen-independent breast cancers.
Deoxygedunin, a Natural Product with Potent Neurotrophic Activity in Mice
Sung-Wuk Jang,Xia Liu,Chi Bun Chan,Stefan A. France,Iqbal Sayeed,Wenxue Tang,Xi Lin,Ge Xiao,Raul Andero,Qiang Chang,Kerry J. Ressler,Keqiang Ye
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0011528
Abstract: Gedunin, a family of natural products from the Indian neem tree, possess a variety of biological activities. Here we report the discovery of deoxygedunin, which activates the mouse TrkB receptor and its downstream signaling cascades. Deoxygedunin is orally available and activates TrkB in mouse brain in a BDNF-independent way. Strikingly, it prevents the degeneration of vestibular ganglion in BDNF ?/? pups. Moreover, deoxygedunin robustly protects rat neurons from cell death in a TrkB-dependent manner. Further, administration of deoxygedunin into mice displays potent neuroprotective, anti-depressant and learning enhancement effects, all of which are mediated by the TrkB receptor. Hence, deoxygedunin imitates BDNF's biological activities through activating TrkB, providing a powerful therapeutic tool for treatment of various neurological diseases.
Perspectives for Sharing Personal Information on Online Social Networks  [PDF]
Chi Kin Chan, Johanna Virkki
Social Networking (SN) , 2014, DOI: 10.4236/sn.2014.31005
Abstract:

The goal of this research was to study how people feel about sharing personal information on social networks. The research was done by interviews; 50 people were interviewed, mostly from mainland China, Hong Kong, and Finland. This paper presents the included 12 questions and discusses the collected answers. It was discovered, e.g., that 38 out of the 50 answerers use social media every day and share versatile personal information on the Internet. Half of the answerers also share information about other people on the Internet. It was also discovered that compared to male answerers, the female answerers were more active in sharing information about other people. There was a significant variety in opinions: what should be the age limit for sharing personal information online, while 22 out of the 50 answerers felt that there is no need for an age limit at all. According to the answers, only a few people use social media for making new friends. Instead, an important reason for using social media is that their existing friends are using. An interesting finding was that the answerers see the Internet as a part of the real world; the privacy that you have on the Internet is the privacy that you have in the real world.

A Lectin with Highly Potent Inhibitory Activity toward Breast Cancer Cells from Edible Tubers of Dioscorea opposita cv. Nagaimo
Yau Sang Chan, Tzi Bun Ng
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0054212
Abstract: A 70-kDa galactose-specific lectin was purified from the tubers of Dioscorea opposita cv. nagaimo. The purification involved three chromatographic steps: anion exchange chromatography on a Q-Sepharose column, FPLC-anion exchange chromatography on a Mono Q column, and FPLC-gel filtration on a Superdex 75 column. The purified nagaimo lectin presented as a single 35-kDa band in reducing SDS-PAGE while it exhibited a 70-kDa single band in non-reducing SDS-PAGE suggesting its dimeric nature. Nagaimo lectin displayed moderate thermostability, retaining full hemagglutinating activity after heating up to 62°C for 30 minutes. It also manifested stability over a wide pH range from pH 2 to 13. Nagaimo lectin was a galactose-specific lectin, as evidenced by binding with galactose and galactose-containing sugars such as lactose and raffinose. The minimum concentration of galactose, lactose and raffinose required to exert an inhibitory effect on hemagglutinating activity of nagaimo lectin was 20 mM, 5 mM and 40 mM, respectively. Nagaimo lectin inhibited the growth of some cancer cell lines including breast cancer MCF7 cells, hepatoma HepG2 cells and nasopharyngeal carcinoma CNE2 cells, with IC50 values of 3.71 μM, 7.12 μM and 19.79 μM, respectively, after 24 hour treatment with nagaimo lectin. The induction of phosphatidylserine externalization and mitochondrial depolarization indicated that nagaimo lectin evoked apoptosis in MCF7 cells. However, the anti-proliferative activity of nagaimo lectin was not blocked by application of galactose, signifying that the activity was not related to the carbohydrate binding specificity of the lectin.
Treatment Satisfaction with Insulin Glargine in Insulin-Naïve Type 2 Diabetes Patients—A Hong Kong Based Registry  [PDF]
Wing-Bun Chan, Wilson W. M. Ngai, Peter Chun-Yip Tong
Journal of Diabetes Mellitus (JDM) , 2014, DOI: 10.4236/jdm.2014.43033
Abstract:

Objective: To evaluate patient satisfaction with insulin glargine. Design: Multicentre observational registry. Data were collected at baseline/inclusion visit, and 12 and 24 weeks. Setting: Physicians in Hong Kong, who managed type 2 diabetes patients and had >5 years’ experience in using insulin glargine. Patients: People with type 2 diabetes, new to insulin, aged 18 - 75 years, who were previously being treated with ≤3 oral antidiabetes drugs (OAD) and had HbA1c > 7%, and in whom the physicians had chosen to prescribe glargine for the first time. Main outcome measures: Treatment satisfaction assessed by Diabetes Treatment Satisfaction Questionnaire (DTSQs), glycaemic control (fasting blood glucose and HbA1c) and adverse events. Results: Between April 2010-October 2011, 41 patients completed the study. Average duration of diabetes and OAD therapy was 7.8 ± 8.0 years and 6.7 ± 7.4 years, respectively. The global DTSQs treatment satisfaction scores improved from 20.9 at baseline to 28.4 (p < 0.05) at the end of 24 weeks insulin glargine treatment. Analysis of DTSQs scores showed a decrease in perceived frequency of hyperglycaemia (4.1 to 1.9, p < 0.001) and hypoglycemia (2.2 to 1.5, p = 0.079). Perceived convenience (0.60, p < 0.025) and flexibility (0.9, p < 0.009) were also improved from baseline. Reduction in mean HbA1c (10.2% ± 2.2% to 7.0% ± 1.0%) and fasting blood glucose (10.9 ± 4.0 mmol/L to 6.4 ± 1.8 mmol/L) from baseline to study termination was significant (p < 0.05). Almost half (48.7%) of patients achieved HbA1c ≤ 7.0%, while 26.0% patients had FBG < 5.6 mmol/L. In total, 9 (22.0%) patients experienced at least one hypoglycemia event; there were no reports of severe hypoglycaemia. Conclusions: Despite a small number of subjects completed in this study, the study demonstrated clearly that the addition of insulin glargine to OAD therapy in diabetes management improved treatment satisfaction and perceived frequency of hyper-and hypoglycaemia together with glycaemic control close to recommended target without severe side-effects in this cohort of patients in Hong Kong.

The Outcome of the Oxidations of Unusual Enediamide Motifs Is Governed by the Stabilities of the Intermediate Iminium Ions
Muneer Ahamed, Bun Chan, Paul Jensen, Matthew H. Todd
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0047224
Abstract: We compare the results from the oxidation of two unusual “enediamide” motifs (3,4-dihydropyrazin-2(1H)-ones), where a double bond is flanked by two amides. In one case the oxidation led to a ring-opened product arising from the cleavage of the double bond, and in the other a rare cis-dioxygenated compound was obtained. Both products have been characterized by X-ray crystallography. The outcomes of the key reactions are rationalized based on calculated free energies of intermediates.
Poisson noise induced switching in driven micromechanical resonators
Jie Zou,Sanal Buvaev,Mark Dykman,Ho Bun Chan
Physics , 2011, DOI: 10.1103/PhysRevB.86.155420
Abstract: We study Poisson-noise induced switching between coexisting vibrational states in driven nonlinear micromechanical resonators. In contrast to Gaussian noise induced switching, the measured logarithm of the switching rate is proportional not to the reciprocal noise intensity, but to its logarithm, for fixed pulse area. We also find that the switching rate logarithm varies as a square root of the distance to the bifurcation point, instead of the conventional scaling with exponent 3/2.
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