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Influence of the aspect ratio on the endovascular treatment of intracranial aneurysms: A computational investigation

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Journal of Biomedical Science and Engineering 2012年第8期5卷 422-431页

作者： Abraham Yik-Sau Tang Siu-kai Lai kar-Ming leung gilberto ka-kit leung Kwok-Wing Chow Department of Mechanical Engineering University of Hong Kong Pokfulam Hong Kong Department of Neurosurgery Kwong Wah Hospital Hong Kong Division of Neurosurgery Department of Surgery Li Ka Shing Faculty of Medicine University of Hong Kong Queen Mary

Intracranial aneurysm, a localized dilation of arterial blood vessels in the Circle of Willis and its branches, is potentially life threatening, due to massive bleeding in the subarachnoid space upon rupture. In clinical practice, one minimally invasive surgical procedure is the implantation of a metallic stent to cover the aneurysm neck. This flow diverting device can reduce the flow into the aneurysm and enhance the prospect of thrombosis, a condition expected to reduce the risk of growth and rupture. The biomechanical and haemo-dynamic factors in stented and nonstented situations are studied by computational fluid dynamics. Unlike earlier models with straight or curved parent blood vessels, the aneurysm is now located near an arterial bifurcation. The influence of the aspect (depth to neck) ratio of the aneurysm on the flow dynamics will be emphasized, especially in the post-operation stages. More precisely, the maximum flow velocity, the variations of wall shear stress, the risk of stent migration and volumetric flow rate after endovascular treatment will be studied. Aneurysms with larger aspect ratios (i.e. smaller neck sizes for constant depth) generally pose a greater risk in terms of these flow parameters. These results will assist the applications and design of stents in future neurosurgical therapy. The approach is limited to a nonelastic model, without taking into account of questions like stent expansion and interaction with tissue.

关键词： Intracranial Aneurysm Endovascular Treatment Stent Aspect Ratio Computational Fluid Dynamics

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Gastrointestinal bleeding in patients on novel oral anticoagulants:Risk,prevention and management

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World Journal of Gastroenterology 2017年第11期23卷 1954-1963页

作者： ka-Shing Cheung Wai K leung Department of Medicine The University of Hong KongQueen Mary HospitalHong KongChina

Novel oral anticoagulants(NOACs), which include direct thrombin inhibitor(dabigatran) and direct factor Xa inhibitors(rivaroxaban, apixaban and edoxaban), are gaining popularity in the prevention of embolic stroke in non-valvular atrial fibrillation as well as in the prevention and treatment of venous thromboembolism. However, similar to traditional anticoagulants, NOACs have the side effects of bleeding, including gastrointestinal bleeding(GIB). Results from both randomized clinical trials and observations studies suggest that high-dose dabigatran(150 mg b.i.d), rivaroxaban and high-dose edoxaban(60 mg daily) are associated with a higher risk of GIB compared with warfarin. Other risk factors of NOAC-related GIB include concomitant use of ulcerogenic agents, older age, renal impairment, Helicobacter pylori infection and a past history of GIB. Prevention of NOAC-related GIB includes proper patient selection, using a lower dose of certain NOACs and in patients with renal impairment, correction of modifiable risk factors, and prescription of gastroprotective agents. Overt GIB can be managed by withholding NOACs followed by delayed endoscopic treatment. In severe bleeding, additional measures include administration of activated charcoal, use of specific reversal agents such as idarucizumab for dabigatran and andexanent alfa for factor Xa inhibitors, and urgent endoscopic management.

关键词： Warfarin Endoscopy Apixaban Edoxaban Gastrointestinal bleeding Dabigatran Rivaroxaban Novel anticoagulants

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Pediatric COVID‑19:what disease is this?

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World Journal of Pediatrics 2020年第4期16卷 323-325页

作者： kam Lun Ellis Hon karen ka Yan leung Department of Paediatrics and Adolescent Medicine The Hong Kong Children’s HospitalHong Kong SARChina

The coronavirus disease 2019(COVID-19)pandemic spares no nations or cities causing escalating incidence and ***,prime ministers,celebrities and high government officials alike have been affected by the *** peculiar reasons,children and infants have generally been spared in Hong Kong,China until recently,when returning students from affected cities with the virus who largely presented with mild *** fact,several countries have reported on pediatric COVID-19.

关键词： mortality officials Royal

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Can progesterone be a better alternative to dexamethasone for use in routine brain surgery?

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Neural Regeneration Research 2015年第9期10卷 1379-1380页

作者： Stephen Y.Cheng gilberto K.K.leung Division of Neurosurgery Department of Surgery Li Ka Shing Faculty of Medicine The University of Hong Kong Queen Mary Hospital

Can progesterone be a better alternative to dexamethasone for use in routine brain surgery？ Surgical brain injury （SBI） is a form of brain trauma caused by various forms of neurosurgical interventions including bra... 详细信息

关键词： TBI Can progesterone be a better alternative to dexamethasone for use in routine brain surgery SBI

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Structure and sequence analysis of influenza A virus nucleoprotein

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Science China(Life Sciences) 2009年第5期52卷 439-449页

作者： NG Andy ka-leung SHAW Pang-Chui Molecular Biotechnology Programme Department of Biochemistry and Centre for Protein Science and Crystallography The Chi-nese University of Hong Kong

Influenza A virus nucleoprotein (NP) forms homo-oligomers and multiple copies of NP wrap around genomic RNA, along with a trimeric polymerase making up ribonucleoprotein (RNP) complex. Sequence comparison of more than 2500 influenza A NP showed that this protein contains 30.1 % of polymorphic residues. NP is composed of a head and a body domain and a tail loop/ linker region. The head domain is more conserved than the body domain, as revealed from the structure-based sequence alignment. NP oligomerization is mediated by the insertion of the non-polymorphic and structurally conserved tail loop of one NP molecule to a groove of another NP. The different form of NP oligomers is due to the flexibility of the polymorphic linkers that join the tail loop to the rest of the protein. The RNA binding property of NP is known to involve the protruding element and the flexible basic loop between the head and body domains, both having high degree of primary sequence conservation. To bind RNA, NP may first capture the RNA by the flexible basic loop and then the RNA is clamped by the protruding element.

关键词： Influenza H5N1 nucleoprotein oligomerization RNA binding

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Risk of gastric cancer development after eradication of Helicobacter pylori

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World Journal of Gastrointestinal Oncology 2018年第5期10卷 115-123页

作者： ka-Shing cheung Wai K leung Department of Medicine The University of Hong Kong Queen Mary Hospital

Helicobacter pylori(H. pylori) infection is the most important risk factor for gastric cancer(gc) development through the correa's gastric carcinogenesis cascade. However, H. pylori eradication alone does not eliminate gc, as pre-neoplastic lesions(atrophic gastritis, intestinal metaplasia and dysplasia) may have already developed in some patients. It is therefore necessary to identify patients at high-risk for gastric cancer after H. pylori eradication to streamline the management plan. If the patients have not undergone endoscopy with histologic assessment, the identification of certain clinical risk factors and non-invasive testing(serum pepsinogen) can predict the risk of atrophic gastritis. For those with suspected atrophic gastritis, further risk stratification by endoscopy with histologic assessment according to validated histologic staging systems would be advisable. Patients with higher stages may require long-term endoscopic surveillance. Apart from secondary prevention to reduce deaths by diagnosing gc at an early stage, identifying medications that could potentially modify the gc risk would be desirable. The potential roles of a number of medications have been suggested by various studies, including proton pump inhibitors(PPIs), aspirin, statins and metformin. However, there are currently no randomized clinical trials to address the impact of these medications on gc risk after H. pylori eradication. In addition, most of these studies failed to adjust for the effect of concurrent medications on gc risk. Recently, large population-based retrospective cohort studies have shown that PPIs were associated with an increased gc risk after H. pylori eradication, while aspirin was associated with a lower risk. The roles of other agents in reducing gc risk after H. pylori eradication remain to be determined.

关键词： Gastric adenocarcinoma Stomach cancer Helicobacter pylori Chemoprevention Intestinal metaplasia

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Application of Big Data analysis in gastrointestinal research

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World Journal of Gastroenterology 2019年第24期25卷 2990-3008页

作者： ka-Shing Cheung Wai K leung Wai-kay Seto Department of Medicine The University of Hong KongQueen Mary HospitalHong KongChina Department of Medicine The University of Hong Kong- Shenzhen HospitalShenzhen 518053Guangdong ProvinceChina

Big Data,which are characterized by certain unique traits like volume,velocity and value,have revolutionized the research of multiple fields including *** Data in health care are defined as large datasets that are collected routinely or automatically,and stored *** the rapidly expanding volume of health data collection,it is envisioned that the Big Data approach can improve not only individual health,but also the performance of health care *** application of Big Data analysis in the field of gastroenterology and hepatology research has also opened new research *** it retains most of the advantages and avoids some of the disadvantages of traditional observational studies(case-control and prospective cohort studies),it allows for phenomapping of disease heterogeneity,enhancement of drug safety,as well as development of precision medicine,prediction models and personalized *** randomized controlled trials,it reflects the real-world situation and studies patients who are often under-represented in randomized controlled ***,residual and/or unmeasured confounding remains a major concern,which requires meticulous study design and various statistical adjustment *** potential drawbacks include data validity,missing data,incomplete data capture due to the unavailability of diagnosis codes for certain clinical situations,and individual *** continuous technological advances,some of the current limitations with Big Data may be further *** review will illustrate the use of Big Data research on gastrointestinal and liver diseases using recently published examples.

关键词： Healthcare dataset Epidemiology Gastric cancer Inflammatory bowel disease Colorectal cancer Hepatocellular carcinoma Gastrointestinal bleeding

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Acupuncture improves cognitive function A systematic review

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Neural Regeneration Research 2013年第18期8卷 1673-1684页

作者： Mason Chin Pang leung ka Keung Yip Chung Tsung Lam ka Shun Lam Wai Lau Wing Lam Yu Amethyst King Man leung Kwok-fai So Department of Rehabilitation Sciences the Hong Kong Polytechnic University Cambridge Regional College Department of Anatomy and the State Key Laboratory of Brain and Cognitive Science the University of Hong Kong Pokfulam Hong Kong Special Administrative Region China GHM Institute of CNS Regeneration Jinan University

BACKGROUND： Acupuncture has been used as a treatment for cognitive impairment. OBJECTIVE： This review assesses clinical evidence for or against acupuncture as a treatment for cognitive impairment. This review also discusses the proposed mechanism（s） that could link acupuncture to improved cognitive function. METHODS： We searched the literature using PolyUone search from its inception to January 2013, with full text available and language limited to English. Levels of evidence were examined using Oxford Centre for Evidence-based Medicine-Levels of Evidence （March, 2009）. RESULTS： Twelve studies met the inclusion criteria： 3 human studies and 9 animal studies. Levels of evidence ranged from level lb to level 5. CONCLUSION： Most animal studies demonstrated a positive effect of acupuncture on cognitive impairment. However, the results of human studies were inconsistent. Further high-quality human studies with greater statistical power are needed to determine the effectiveness of acupuncture and an optimal protocol.

关键词： neural regeneration dementia acupuncture electroacupuncture learning cognitive cognition memory neuroregeneration

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The effects of stent porosity on the endovascular treatment of intracranial aneurysms located near a bifurcation

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Journal of Biomedical Science and Engineering 2013年第8期6卷 812-822页

作者： Abraham Yik-Sau Tang Hiu-Ning Chan Anderson Chun-On Tsang gilberto ka-kit leung kar-Ming leung Alfred Cheuk-Hang Yu Kwok-Wing Chow Department of Mechanical Engineering University of Hong Kong Hong Kong China Department of Neurosurgery Kwong Wah Hospital Hong Kong China Division of Neurosurgery Department of Surgery Li Ka Shing Faculty of Medicine University of Hong Kong Queen Mary Hos-pital Hong Kong China Medical Engineering Program Department of Electrical and Electronic Engineering University of Hong Kong Hong Kong China

Intracranial aneurysm occurs when a cerebral artery develops an abnormal sac-like dilatation, and will cause massive bleeding in the subarachnoid space upon rupture. Endovascular stenting is a minimally invasive procedure in which a flow-diverting stent is deployed to cover the aneurysm neck, thereby restricting blood from entering the aneurysm and reducing the risk of rupture. The stent porosity, a crucial factor determining the intra-aneurysmal hemodynamics following treatment, is investigated by computational fluid dynamics techniques. Based on the computational results, a low porosity stent will dramatically reduce the flow velocity and the flow rate inside the side branch vessel. Conversely, a high porosity stent may not provide adequate flow reduction inside the aneurysm, possibly causing treatment failure. An advisable range of optimal stent porosity would be 60% to 75%, which can drastically reduce the flow rate into the aneurysm while preserving enough blood flow for the side branch vessel. Clinically, deployment of two or more flow-diverting stents may not increase treatment efficacy but can potentially lead to adverse effects due to side-branch hypoperfusion. The present quantitative analysis can also provide practical insight for future stent design.

关键词： Intracranial aneurysm Endovascular Treatment Stent Stent Porosity Computational Fluid Dynamics

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Mechanism of metastasis by membrane type 1-matrix metalloproteinase in hepatocellular carcinoma

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World Journal of Gastroenterology 2005年第40期11卷 6269-6276页

作者： Ying-Chi Ip Siu-Tim Cheung ka-Ling leung Sheung-Tat Fan Centre for the Study of Liver Disease and Department of Surgery

AIM To investigate the precise role of membrane type 1-matrix metalloproteinase （NTI-NNP） in hepatocellular carcinoma （HCC） metastasis. METHODS- Human HCC cells Hep3B with overexpression of MTT-MMP were established by stable transfection, and compared with control cells carrying the empty vector. Cells were examined in vivo for their differences in the metastatic ability of athymic nude mice, and analyzed in vito for their differences in invasion ability by invasion chamber coated with Matrigel, adhesion towards collagen I and migration through culture chamber. Cell proliferation and apoptosis in adherent and suspension status were evaluated by MTr and flow cytometry analysis. RESULTS We found that overexpression of MT1-MMP could increase intrahepatic metastasis in nude mice with orthotopic implantation of HCC cells （incidence of 100% [MT1-MMP transfectants] vs 40% [vector control transfectants], P〈0.05）. NT1-MMP could also enhance cell invasion through Natrigel （107.7 vs 39.3 cells/field, P〈0.001）, adhesion towards matrix （0.30 vs 0.12 absorbance unit at 540 nm, P〈0.001）, cell migration （89.3 vs 39.0 cells/field, P〈0.001）, and cell proliferation （24.3 vs 40.5 h/doubling, P〈0.001）. We also observed that NTI-NNP supported cell survival （71.4% vs 23.9%, P〈0.001） with reduced apoptosis （43.7% vs51.0%, P〈0.05） in an attachment-free environment. CONCLUSION： MT1-MMP overexpression could enhance metastasis. In addition to its active role in matrix degradation during tumor invasion, MT1-MMP enhances tumor cell survival upon challenge of detachment, which is important during metastasis when cells enter the circulation.

关键词： MT1-MMPIMMP14 Liver cancer Invasion Metastasis

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