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Biomedical subjects

K Y Chan

Publications and source records attributed to K Y Chan.

At least 19 recordsLinked to original sources
PubMed2006

Electrochemical degradation of 4-chlorophenol at nickel-antimony doped tin oxide electrode.

The effectiveness of a novel nickel-antimony doped tin oxide electrode for electrochemical degradation of organic pollutants was investigated using 4-chlorophenol (4-CP) as a model toxic organic. The experimental results demonstrate that the optimal Ni content was at Ni:Sn=1:500 in atomic ratio in the precursor coating solution, whereas the Sb:Sn ratio was set at 8:500. Using the electrode prepared with the optimal Ni doping ratio for 4-CP degradation, the charge-based efficiencies were up to 89 microg C(-1) for 4-CP destruction and 15 microg C(-1) for TOC removal, which were considerably higher than the efficiencies observed for other electrodes. It is suggested that the enhancement of the electrode for electrochemical oxidation of organics could be attributed to the production of hydroxyl radicals in anodic water electrolysis.

Antimony↗
PubMed2006

Nitrogen removal from the saline sludge liquor by electrochemical denitrification.

Sludge liquor from the sludge dewatering process has a high ammonia content. In the present study, a lab-scale electrochemical (EC) system with a pair of Ti electrode plates was used for treating the sludge centrate liquor of digested wastewater sludge with a NH4(+) - N content of around 500 mg/L. The sludge liquor had a high salinity due to seawater being used for toilet flushing in Hong Kong. The results show that the EC process is highly effective for denitrification of the saline sludge liquor. Complete nitrogen removal could be achieved within 1 hr or so. The rate of EC denitrification increased with the current intensity applied. The best current efficiency for nitrogen removal was obtained for a gap distance between the electrodes at 8 mm. Electro-chlorination was considered to be the major mechanism of EC denitrification. The formation of chlorination by-products (CBPs) appeared to be minimal with the total trihalomethanes (THM) detected at a level of 300 microg/L or lower. The power consumption for EC denitrification was around 23 kWh/kg N. Additional electro-flocculation with a pair of iron needle electrodes could enhance the flocculation and subsequent sedimentation of colloidal organics in the sludge liquor, increasing the organic removal from less than 30% to more than 70%. Therefore, the EC process including both electro-denitrification and electro-flocculation can be developed as the most cost-effective method for treatment of the saline sludge liquor.

Bioreactors↗
PubMed2005

A method for the quantitative analysis of the layering of HIV-related stigma.

HIV-related stigma is regarded as one of the major barriers in the development of effective prevention and care programs; but the stigma associated with HIV stigma is not a singular entity. The stigma of the infection is layered with other stigmas, such as those associated with the routes of transmission (e.g., sex work and injecting drug use) and personal characteristics (e.g., race, religion, ethnicity and gender). In developing programs and policies to overcome HIV-related stigma, cognisance needs to be taken of all the sources of stigma, and how they may interact. A novel method is described for examining the layers of HIV/AIDS-related stigma, and secondary data are adapted to illustrate this. The importance of understanding the layering of stigma for the development of effective interventions is also discussed.

HIV Infections↗
PubMed2005

Institutional and structural forms of HIV-related discrimination in health care: a study set in Beijing.

This paper presents key findings of a situational analysis of institutional and structural levels of HIV/AIDS-related discrimination in Beijing, China, with a focus on the area of health care. Initially slow to respond to the presence of HIV, China has altered its approach and enacted strict legislative protection for people living with HIV/AIDS (PLWHA). In order to determine whether this has altered discrimination against PLWHA, this study examined existing legislation and policy, and interviewed key informants working in health care and PLWHA. The overall findings revealed that discrimination in its many forms continued to occur in practice despite China's generally strong legislative protection, and it is the actual practice that is hindering PLWHAs' access to health services. A number of legislative and policy gaps that allow discrimination to occur in practice were also identified and discussed. The paper concludes with a call to rectify specific gaps between legislation, policy and practice. An understanding of the underlying factors that drive discrimination will also be necessary for effective strategic interventions to be developed and implemented.

Acquired Immunodeficiency Syndrome↗
PubMed2005

Future research on structural and institutional forms of HIV discrimination.

There is scant research into HIV discrimination, particularly structural and institutional forms of it. This appears, in part, to arise from a prevailing view that the solutions to HIV discrimination are known a priori and in the absence of additional data. The six country studies into HIV discrimination presented in this AIDS Care supplement suggest that this is not the case. There needs to be an acceptance that if the issue of HIV discrimination is to be tackled successfully and based on evidence, then incremental and effortful steps need to be taken to develop that evidence base. This is discussed.

Forecasting↗
PubMed2005

An Asia Pacific six-country study on HIV-related discrimination: introduction.

This paper outlines a six-country study of institutionalised forms of HIV/AIDS-related discrimination in the Asia-Pacific region. Although recognised as a barrier to disease prevention and treatment, very limited data are available on the effects of institutionalised HIV-related stigma and discrimination. Understanding the forms of discrimination within the institutions where they occur is the first step to identifying effective ways of promoting compassionate, non-discriminatory treatment of PLWHA. Thus, the goal of this research project was to document institutional discrimination against PLWHA, as guided by the UNAIDS Protocol for the Identification of Discrimination Against People Living with HIV (2000), in six Asian countries: India, Thailand, Philippines, China, Vietnam and Indonesia. As a precursor to the six individual studies, this paper provides a brief overview of the literature on HIV discrimination, and then describes the UNAIDS Protocol and the shared methodological considerations relevant to all of the study sites. Commonalities in sampling, procedures and analysis are also discussed.

Asia↗
PubMed2005

Methodological considerations in the measurement of institutional and structural forms of HIV discrimination.

The systematic measurement of HIV/AIDS-related discrimination is imperative within the current rhetoric that holds discrimination as one of the two 'biggest' barriers to HIV/AIDS pandemic intervention. This paper provides a methodological critique of the UNAIDS (2000b) Protocol for the Identification of Discrimination against People Living with HIV (the Protocol). Specifically, the paper focuses on the Protocol's capacity to accurately identify and measure institutional levels of HIV-related discrimination that allows data that are reliable and comparable across time and contexts. Conceptual issues including the Protocol's objective as an indicator versus a direct measure of discrimination and the role of the Protocol as a tool of research versus a tool of advocacy are explored. Design issues such as the operationalization of discrimination, appropriateness of indicator content, sampling and data collection strategies and issues of scoring are also evaluated. It is hoped that the matters outlined will provide readers with ways of critically reflecting and evaluating the findings of the research papers presented in this Special Issue, as well as pointing to ways of improving research design.

HIV Infections↗
PubMed2005

HIV discrimination: integrating the results from a six-country situational analysis in the Asia Pacific.

The findings of the six independent studies on institutional forms of HIV discrimination in the Asia Pacific presented in this Special Issue of AIDS Care are integrated. At first glance, the general pattern of the results across the study sites suggests that discrimination is most pertinent in the domain of 'practice' rather than in the domains of law or institutional policy. On closer analysis, however, utilising the qualitative data, this conclusion does not take sufficient account of the cultural context within which the interpersonal interaction (practice) between the health carers and people living with HIV/AIDS occurs. Limitations on the use of anti-discrimination legislations and protective written policies for reducing discrimination in these contexts are discussed. The need for alternative approaches to thinking about discrimination intervention is raised and this is done through a consideration of the strategy of universal precautions.

Acquired Immunodeficiency Syndrome↗
PubMed2005

Surveillance of acute flaccid paralysis in Hong Kong: 1997 to 2002.

OBJECTIVES: To describe the characteristics of patients reported with acute flaccid paralysis between 1997 and 2002, and to evaluate the performance of the acute flaccid paralysis surveillance system using indicators recommended by the World Health Organization. DESIGN: Retrospective study. SETTING: Department of Health, Hong Kong. PARTICIPANTS: Children aged younger than 15 years who were reported to the Department of Health between 1997 and 2002 with acute flaccid paralysis. RESULTS: Of 120 children with acute flaccid paralysis reported between 1997 and 2002, 42% were younger than 5 years of age. None of the cases were acute poliomyelitis or polio-compatible. A neurological cause was identified in 67.5% of cases, of which the most common was Guillain-Barre syndrome (42%), followed by transverse myelitis (15%). All except one of the performance indicators consistently met World Health Organization requirements and thus demonstrated the effectiveness of the acute flaccid paralysis surveillance programme. The acute flaccid paralysis notification rate consistently exceeded 1.0 per 100 000 population below 15 years of age. The requirement for adequate stool investigation was the single indicator that did not satisfy World Health Organization requirements. This highlighted the importance of maintaining physicians' awareness of acute flaccid paralysis surveillance. CONCLUSION: Hong Kong should remain vigilant for acute flaccid paralysis. The effective surveillance system and its evaluation may serve as a model for surveillance of other infectious diseases.

Acute Disease↗
PubMed2005

Herpetic shoulder paresis in a Chinese elderly patient.

A patient with left shoulder girdle weakness secondary to herpetic myotomal paresis is reported. Needle electromyography revealed denervational discharge from the left supraspinatus, deltoid, and brachioradialis muscles, compatible with a radiculopathy that was relevant to his myotomes affected by zoster infection. The patient was managed with range-of-movement and strengthening exercises as well as pain relief for post-herpetic neuralgia. Further studies are required to determine whether antiviral treatment can limit the extent of motor deficit and hasten recovery. Zoster paresis should be one of the differential diagnoses of girdle muscle weakness.

Aged↗
PubMed2005

A review of day care ureteroscopy of a teaching hospital in Malaysia.

This is a retrospective review of 200 day-care ureteroscopies performed between April 1998 and October 2002. The aim was to determine the feasibility and safety of this procedure. The mean age was 38.8 years and 75% of them were male. Eighty-three percent were ASA 1 and the remainders were ASA 2. The side of procedure were 48.5% right, 2.5% left and 6% both sides. Fentanyl and proprofol were used during induction. Calculi were found in 82.5% of cases. Rigid and flexible scope were used in 91.5% and 10.5% of cases. There were 33% upper, 23% mid and 44% distal ureteric stones. The mean stone size was 9.37 X 6.93mm. Seventy-four percent required a ureteric stent insertion. The mean operative time was 58.3 minutes. Four percent of patients experienced pain post-operatively relieved by NSAID injection. Repeat ureteroscopy performed in 30% of patients. There were zero admission rates. This study suggests day-care ureteroscopy is effective, safe and well tolerated by patients.

Adolescent↗
PubMed2005

Case report of a difficult venous access: retroperitoneal approach of inserting an improved non-heparinised port for long-term use.

This is a case report of a patient with difficult venous access following thrombosis of major superficial and deep veins of the limbs as documented by ultrasound doppler and venography. The insertion of a few central ports were infected and the vein thrombosed. Venography revealed that central venous access was no longer feasible. The previous laparotomies had resulted in dense intra-peritoneal adhesions, and rendered further laparotomy virtually impossible. The patient had occasional adhesion colics, vomiting and hypoglycemic episodes. A rarely performed retro-peritoneal approach of inserting an improved non-heparinised port proved to be effective for long-term management of this patient. The surgical approach and the selected port are discussed.

Adult↗
PubMed2005

Review of risk factors associated with the anastomosis leakage in anterior resection in Hospital Universiti Kebangsaan Malaysia.

This is a retrospective study evaluating the risk factors for clinical anastomotic leakage after anterior resection in 64 patients with rectal cancer operated from November 2001 till August 2003. The percentage of anastomosis leakage was higher in those patients with diabetic, low albumin level, neoadjuvant radiotherapy, higher staging, and poorly differentiated tumour. However, these differences were statistically not significant. There was a significant difference (p=0.03) of anastomosis leakage in those patients with very distal tumour of < 4cm from anal verge (42%), when compare to those patients with proximal tumor of > 15cm from anal verge (4.3%). The mortality associated with this complication was 30%. Hence, a surgeon may consider a covering stoma or be more vigilant in operating patients with multiple risk factors.

Adenocarcinoma↗
PubMed2005

The incidence of deep venous thrombosis following arthroscopic knee surgery.

A prospective cohort study was undertaken at two centers to look for the incidence of deep vein thrombosis (DVT) following knee arthroscopic surgery. Eighty-four patients who had 90 arthroscopic procedures were reviewed. The relevant risk factors: past or family history of DVT, smoking, oral contraceptives, body weight, haemoglobin level, platelet count, tourniquet time and type of anaesthesia were documented. All patients were subjected to preoperative and post-operative duplex ultrasound. Only one patient (1.2 %) was noted to have DVT involving the peroneal vein. We concluded that the incidence of DVT after knee arthroscopy was very low in this study population.

Adolescent↗
PubMed2005

Colonies in engineered articular cartilage express superior differentiation.

In view of poor regeneration potential of the articular cartilage, in-vitro engineering of cartilage tissue offers a promising option for progressive joint disease. This study aims to develop a biologically engineered articular cartilage for autologous transplantation. The initial work involved determination of chondrocyte yield and viability, and morphological analysis. Cartilage was harvested from the knee, hip and shoulder joints of adult New Zealand white rabbits and chondrocytes were isolated by enzymatic digestion of the extra-cellular matrix before serial cultivation in DMEM/Ham's F12 media as monolayer cultures. No differences were noted in cell yield. Although chondrocytes viability was optimal (>93%) following harvest from native cartilage, their viability tended to be lowered on passaging. Chondrocytes aggregated in isogenous colonies comprising ovoid cells with intimate intracellular contacts and readily exhibited Safranin-O positive matrix; features typically associated with articular cartilage in-vivo. However, chondrocytes also existed concurrently in scattered bipolar/multipolar forms lacking Safranin-O expression. Therefore, early data demonstrated successful serial culture of adult chondrocytes with differentiated morphology seen in established chondrocyte colonies synthesizing matrix proteoglycans.

Animals↗
PubMed2004

Anomalous diffusivity and electric conductivity for low concentration electrolytes in nanopores.

We apply equilibrium and nonequilibrium molecular dynamics simulations to study the dynamic properties of electrolytes in nanopores. The realistic primitive model and the restrictive primitive model widely used in the statistical mechanics of liquid-state theory are applied to model the electrolytes. The electrolytic ions are immersed in water, treated in this work as either a dielectric continuum ignoring the size of solvent molecules or a macroscopic dielectric continuum (polar property) plus neutral soft spheres, and the aqueous electrolyte is put in a confined space. To simulate a condition mimicking closely processes of practical interest and yet maintaining the simulation computationally manageable, we consider an infinitely long and uncharged cylindrical tube. The equilibrium property of the self-diffusion coefficient D and the nonequilibrium property of electric conductivity sigma are computed in terms of electrolyte concentration, particle size, and cylindrical pore radius. The simulation results for the continuum solvent restrictive primitive model and continuum solvent primitive model show normal behavior for D versus pore radius R at ionic concentration 0.1M -i.e., D decreases with decreasing R -display an R independence of D at a certain threshold concentration and undergo an anomalous increase in D with reducing R at a lower value 0.025 M. The mechanism of the anomaly at the ionic concentration 0.025 M was sought for and interpreted in this work to arise from the energetic and entropic factors. Our simulated data of sigma at this same concentration follow the same trend as D. To delve further into the transport properties, we perform simulation studies for the discrete solvent primitive model and make a detailed analysis of the characteristic of the ion radial density functions. Comparison of the latter functions with those in the continuum solvent primitive model sheds light on the simulated diffusion coefficient within the context of discrete solvent primitive model which is about two orders of magnitude less. This difference in D is naturally attributed to the solvent effect. Similar disparities were reported by others for the discrete and continuum restrictive primitive models.

Journal Article↗
PubMed2004

Spontaneous closure of a persistent post-traumatic pancreatic fistula in a child: incidental therapeutic effect of ERCP.

A child with a post-tramatic pancreatic pseuodocyst developed pancreatic fistula, following percutaneous drainage of the cyst. The fistula output was about 120ml/day and lasted for a month. A diagnostic ERCP revealed main pancreatic duct disruption. The fistula output ceased over the next two days following the ERCP. The patient has been well for the past four years. This patient's immediate recovery after ERCP could possibly be due to dislodgement of a mucus plug by the contrast injected during ERCP. Such a mechanism can explain the previous sporadic reports of spontaneous cure of persistent pancreatic fistulae in children.

Child↗