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Biomedical subjects

K Chan

Publications and source records attributed to K Chan.

At least 19 recordsLinked to original sources
PubMed2007

HIV and ethnicity in Canada: is the HIV risk-taking behaviour of young foreign-born MSM similar to Canadian born MSM?

There is a dearth of information on the HIV risk-taking behaviour of foreign-born men who have sex with men (MSM) in Canada. This study focused on identifying sexual risk behaviour among MSM who immigrated to Canada and compared them to MSM who were born in Canada. Baseline data from the Omega Cohort in Montreal and the Vanguard Project in Vancouver were combined to form four ethnicity/race analytical categories (n = 1,148): White born in Canada (WBIC), White born outside of Canada, non-White born in Canada (NBIC) and non-White born outside of Canada (NBOC). Psychological, demographic and sexual behaviour characteristics of the groups were similar except: NBOC were more likely to be unemployed, less likely to be tattooed, had fewer bisexual experiences and less likely worried of insufficient funds. WBOC were more likely to report unprotected sex with seropositives and more likely to have had unprotected sex while travelling. NBIC were more likely to have ever sold sex and to have had body piercing. WBOC are at high risk of acquiring as well as transmitting HIV. It is important to consider place of birth in addition to ethnicity when developing programmes to prevent the transmission of HIV.

Adolescent↗
PubMed2006

Evaluation of NucliSens EasyQ HIV-1 assay for quantification of HIV-1 subtypes prevalent in South-east Asia.

BACKGROUND: Monitoring anti-retroviral therapy requires that viral load assays for human immunodeficiency virus type 1 (HIV-1) be applicable to diverse HIV-1 subtypes. OBJECTIVES: To evaluate NucliSens EasyQ HIV-1 assay for quantitation of common HIV-1 subtypes prevalent in South-east Asia. STUDY DESIGN: One hundred and nineteen plasma samples collected in Hong Kong and Cambodia were used to compare the performance of NucliSens EasyQ HIV-1 and COBAS Amplicor HIV-1 Monitor version 1.5 assays. Viral RNA extracted from the NucliSens MiniMAG was also used for HIV-1 subtyping. RESULTS: Performance of NucliSens EasyQ correlated well with COBAS Amplicor (r=0.777, p<0.001) and the small mean difference (0.0462log(10)IU/mL) obtained in the Bland and Altman model indicated good agreement between two assays. The NucliSens EasyQ assay demonstrated a 95% sensitivity at 500IU/mL and 100% specificity. Reproducibility of this assay was within log(10)2-4IU/mL and had a coefficient of variation between 2.3% and 10.4%. Among the 109 specimens included in the analysis, HIV-1 subtyping identified 64 CRF01_AE, 38 subtype B, 3 subtype C, 3 CRF07_BC and 1 subtype G viruses. CONCLUSIONS: Performance of NucliSens EasyQ was comparable to COBAS Amplicor for HIV-1 viral load monitoring. RNA extracts from NucliSens MiniMAG could be used for HIV-1 viral load monitoring, subtyping and drug resistance mutations detection. Our findings highlight the versatility of both NucliSens EasyQ and COBAS Amplicor in monitoring prevalent subtypes and rare circulating recombinant forms (CRFs) in the South-east Asia region.

Cambodia↗
PubMed2006

Wide local excision and radiotherapy for the treatment of ductal carcinoma in situ of the breast: the Hong Kong experience.

AIMS: Breast conservation treatment for ductal carcinoma in situ (DCIS) was unpopular in the Chinese population and the outcome was seldom reported. We conducted a single-centre retrospective study to examine the clinical outcome of women in Hong Kong. MATERIALS AND METHODS: Seventy-five Chinese women were treated with wide local excision and radiotherapy for DCIS of the breast between 1994 and 2003. Only 26 (34.7%) women had non-palpable DCIS detected by screening mammograms. All women were treated with whole breast irradiation of 50 Gy in 2 Gy daily fractions, with 50 (66.7%) women receiving an additional electron boost of 10-16 Gy. RESULTS: The median follow-up was 5.1 years (range 2.0-10.7). At the last assessment, four women developed local recurrences, but all remained disease-free after salvage mastectomy. The 5-year actuarial local failure-free rate and cause-specific survival rate were 92.9% (95% confidence interval 89.4-96.4) and 100.0%, respectively. Cosmetic results were rated as good to excellent in all women. On univariate analysis of prognostic factors for local failure, only a close (< or = 2 mm) final resection margin approached statistical significance (hazard ratio 9.108; 95% confidence interval 0.946-87.655; P = 0.056). The 5-year actuarial local failure-free rates for women with a close (< or = 2 mm) final resection margin and women with wider margins were 77.0 and 98.2%, respectively. CONCLUSIONS: Despite geographical and demographic differences, the clinical outcome after wide local excision and radiotherapy for DCIS of the breast in Chinese women is comparable with that in Western series. Efforts are needed to achieve cosmetically acceptable tumour-free margins greater than 2 mm.

Adult↗
PubMed2006

Inadequacies in antiretroviral therapy use among Aboriginal and other Canadian populations.

We undertook this study to provide a profile of Aboriginal people initiating antiretroviral therapy and their response to treatment. Aboriginal peoples were identified through self-report. Baseline socio-demographics and risk factors were compared between Aboriginal and non-Aboriginal participants as were baseline factors associated with two consecutive plasma viral load measures below 500 copies/ml using contingency table analysis. Multivariate survival analysis of the prognostic factors associated with time to two consecutive plasma viral load measures below 500 copies/ml among eligible participants was undertaken to characterize response to antiretroviral therapy. There were 892 participants with available data for this analysis, of those 146 (16%) self-identified as Aboriginal. Aboriginal participants were more likely to be female (p < or = 0.001), have lower baseline plasma viral loads (p = 0.010), be co-infected with HCV (p < 0.001), live in unstable housing (p < or = 0.001), and report an income of >10K CDN (p < or = 0.001) per annum. Aboriginal people were less likely to report men who have sex with men (p < or = 0.001) and more likely to report injection drug use (p < or = 0.001) as a risk factor for HIV infection. Aboriginal participants were more likely to receive double versus triple combination antiretroviral therapy (p = 0.002), be less adherent in the first year on therapy (p = 0.001) and to have a physician less experienced with treating HIV (p < or = 0.001). When these factors were controlled for, Aboriginal people treated with triple combination therapy were as likely to respond and suppress their viral load below 500 copies. In the era of HAART, our results indicate that Aboriginal people living with HIV/AIDS were less likely to receive optimal therapy. However, when Aboriginals did receive triple drug therapy they suppressed just as well as non-Aboriginals.

Adult↗
PubMed2006

What are the barriers faced by general practitioners in treating depression and anxiety in Hong Kong?

Barriers faced by general practitioners in Hong Kong to manage patients with depression and anxiety disorders and their association with postgraduate qualification in family medicine were studied. Postal questionnaires were sent to 179 family medicine tutors affiliated with a university in Hong Kong with a response rate of 64.2%. 'Too time consuming' was the largest barrier for these physicians in treating patients with depression and anxiety. General practitioners without higher qualifications in family medicine were significantly more likely to report 'lack of confidence', 'lack of experience' and 'lack of supporting service' as being the barriers in treating patients with depression and anxiety. Our results showed that time constraint is an important barrier for general practitioners in managing patients with depression and anxiety in Hong Kong. Having a higher qualification in family medicine may reduce the barriers of having lack of confidence and experience in these physicians.

Adult↗
PubMed2005

Clinical utility of genotyping resistance test on determining the mutation patterns in HIV-1 CRF01_AE and subtype B patients receiving antiretroviral therapy in Hong Kong.

BACKGROUND: HIV-1 genotypic resistance test (GRT) has been widely used to monitor HIV infection but only few reports revealed the mutation patterns of non-B HIV-1 subtypes. OBJECTIVE: To evaluate the concordance of GRT and clinical treatment outcomes on different HIV-1 subtypes and monitor the mutation patterns and frequencies. STUDY DESIGN: Pre- and post-treatment plasma samples from 123 patients (39 treatment naïve and 84 treatment experienced) were tested by ViroSeq HIV-1 Genotyping System followed by analysis using the Stanford HIV database. The mutation patterns and frequencies developed in the pol gene were compared among subtypes. RESULTS: HIV-1 subtypes among patients in Hong Kong were mainly subtype B and CRF01_AE. Primary mutation was not detected among all pre-treatment samples. For post-treatment samples, primary mutations were only detected in the treatment failure group. The mutation patterns and frequencies were similar between CRF01_AE and subtype B viruses. However, the frequencies of L74V/I and K103N in the reverse transcriptase region were different between CRF01_AE and subtype B viruses. VirtualPhenotype was unable to analyze an in-frame insertion of arginine and isoleucine at protease codon 35 of one CRF01_AE isolate. CONCLUSIONS: This is the first report to demonstrate the high degree of concordance of longitudinal genotyping data and clinical treatment outcome in patients harboring different HIV-1 subtypes. Our findings shed light to the emergence of resistance mutations and its testing in CRF01_AE, which is relevant to other prevailing places in Asia.

Algorithms↗
PubMed2005

The effects of a Chinese medicinal suppository (Vitalliver) on insulin-like growth factor 1 and homocysteine in patients with hepatitis B infection.

The liver is the major organ for the metabolism of homocysteine (Hcy) and production of insulin-like growth factor 1 (IGF-1). Hcy metabolism and IGF-1 synthesis may be impaired in chronic liver diseases. The study investigated the regulatory effect of a Chinese herbal suppository, Vitalliver, on Hcy and IGF-1, as well as their relationship in patients with hepatitis B infection. Forty patients with chronic hepatitis B virus (HBV) infection without cirrhosis, 25 males and 15 females, were observed for changes in Hcy and IGF-1 after the administration of Vitalliver (one nightly) for a period of 3 months. Serum levels of Hcy, IGF-1 and IGFBP-3 were measured at baseline, and at 1 month and 3 months after treatment. Vitalliver reduced Hcy levels significantly (p = 0.001) from 9.7 +/- 2.8 to 9.0 +/- 2.1 micromol/L after treatment of 3 months. Furthermore, the IGF-1 levels increased significantly (p < 0.001) from 170.2 +/- 81.8 to 212.8 +/- 80.9 ng/mL at 1 month and 187.5 +/- 72.3 ng/mL at 3 months (p = 0.001) after treatment. In conclusion, it is speculated Vitalliver may have a self-regulatory effect on the release of IGF-1 in HBV patients without liver cirrhosis.

Adolescent↗
PubMed2005

Neuropathologically distinct prion strains give rise to similar temporal profiles of behavioral deficits.

Mouse-adapted scrapie strains have been characterized by vacuolation profiles and incubation times, but the behavioral consequences have not been well studied. Here, we compared behavioral impairments produced by ME7, 79A, 22L, and 22A strains in C57BL/6J mice. We show that early impairments on burrowing, glucose consumption, nesting and open field activity, and late stage motor impairments show a very similar temporal sequence in ME7, 79A, and 22L. The long incubation time of the 22A strain produces much later impairments. However, the strains show clear late stage neuropathological differences. All strains showed clear microglial activation and synaptic loss in the hippocampus, but only ME7 and 79A showed significant CA1 neuronal death. Conversely, 22L and 22A showed significant cerebellar Purkinje neuron loss. All strains showed marked thalamic neuronal loss. These behavioral similarities coupled with clear pathological differences could serve to identify key circuits whose early dysfunction underlies the neurological effects of different prion strains.

Animals↗
PubMed2005

Quality of life, depression and fatigue among persons co-infected with HIV and hepatitis C: outcomes from a population-based cohort.

The objective of the study was to describe the additional burden generated by hepatitis C (HCV) infection among HIV-infected individuals as measured by self-reported quality of life, depression and fatigue. The provincial HIV/AIDS Drug Treatment Program (DTP) distributes all antiretroviral medication in the province of British Columbia. Eligibility for accessing antiretrovirals is based on published guidelines commensurate with the International AIDS Society. Each participant is asked to complete a self-administered mailed questionnaire that includes patient sociodemographic information, quality of life measures (Medical Outcomes Study-Short Form (MOS-SF), mental health issues (Centre for Epidemiological Studies Depression scale (CESD) and fatigue information. HIV-HCV co-infected individuals were compared to HIV mono-infected individuals using parametric and nonparametric methods. Multivariate logistic regression was used to examine the impact of hepatitis C on quality of life, depression and fatigue, after controlling for sociodemographics and HIV-specific clinical characteristics. Of the 4,134 individuals who were sent a HIV/AIDS DTP survey in 1999, 2000 or 2001, 484 participants both returned one and had an HCV-antibody test result on file. Of the 484 participants eligible for this analysis, 105 (22%) were HCV-positive. In comparison to the 379 (78%) patients testing negative for HCV, a larger proportion of co-infected patients were female (18% versus 3%, p<0.001), aboriginal (20% versus 3%, p<0.001), had ever injected drugs (79% versus 5%, p<0.001), were unemployed (91% versus 49%, p<0.001) and lived in unstable housing (19% versus 1%, p<0.001) at the time they completed the survey. Co-infected patients reported more symptoms consistent with depression, increased fatigue and poorer quality of life. However, using multivariate modeling, it was determined that the impact of HCV on quality of life, depression and fatigue was better explained by the sociodemographic factors related to poverty and injection drug use, than by HCV itself. In conclusion, individuals co-infected with HIV and HCV represent a patient population with significant physical and mental health challenges. Although these patients experience poorer quality of life, increased depression and fatigue, this experience appears to be primarily related to socio-economic issues rather than HCV infection.

AIDS-Related Opportunistic Infections↗
PubMed2005

Reducing discriminatory attitudes toward people living with HIV/AIDS (PLWHA) in Hong Kong: an intervention study using an integrated knowledge-based PLWHA participation and cognitive approach.

The present paper describes the development and evaluation of an intervention programme aiming to reduce adolescents' discriminatory attitudes toward people living with HIV/AIDS (PLWHA). The intervention programme integrates components of 'virtual interaction' with PLWHA (watching a documentary), knowledge enhancement and a simple cognitive exercise. To evaluate its effectiveness, the programme was implemented to about 600 form 3-4 (grade 9-10) students of three secondary schools in Hong Kong. Using a structured questionnaire, the level of discriminatory attitudes toward PLWHA, knowledge about HIV/AIDS and perceptions about PLWHA, etc. were measured before and after the implementation of the programme. A notable improvement on the level of acceptance of PLWHA and knowledge about HIV/AIDS was found after the implementation of the programme. Negative perceptions about PLWHA also reduced substantially. For instance, before the programme, over one-third (35.7%) of all respondents believed that the majority of PLWHA were promiscuous; the figure dropped to 15.8% after exposure to the programme (adjusted odds ratio = 0.35, p < 0.001). Further, some gender differences were observed. Female respondents tended to be less discriminatory toward PLWHA and responded more favourably to the programme than their male counterparts.

Acquired Immunodeficiency Syndrome↗
PubMed2005

Does pulmonary rehabilitation give additional benefit over tiotropium therapy in primary care management of chronic obstructive pulmonary disease? Randomized controlled clinical trial in Hong Kong Chinese.

OBJECTIVE: To evaluate whether multidisciplinary pulmonary rehabilitation programme (PRP) provides additional benefit over tiotropium therapy in managing chronic obstructive pulmonary disease (COPD) in primary care. DESIGN: A randomized controlled trial to analyse the difference in outcomes of COPD patients receiving tiotropium plus PRP vs. tiotropium treatment alone. SETTING: Two primary care teaching clinics affiliated with a university which serves a population of 600,000. PARTICIPANTS: Fifty primary care COPD patients. METHODS: Fifty subjects underwent spirometry and their status of COPD was confirmed by using the Vitalograph Gold Standard. They were then assessed by the 6-min walking distance (6MWD), Peak Visual Analogue Scale (Peak VAS) and Chronic Respiratory Disease Questionnaire (CRQ). All subjects were given tiotropium to optimize their treatment. After a 6-week period, half were randomized to the intervention group (i.e. receiving PRP), whereas the rest were randomized to control group which received only medication. Spirometry, 6MWD, Peak VAS and CRQ were performed in both groups at 6 weeks, 12 weeks and 3 months. OUTCOMES: Spirometry, 6MWD, Peak VAS and CRQ. RESULTS: Significant improvement (P < 0.05) was seen in 6MWD, symptoms of dyspnoea measured by Peak VAS and CRQ. The improvement was sustained at 3-month follow-up. However, no additional significant improvement was seen in the intervention group when compared with control. CONCLUSION: Tiotropium therapy has improved health outcomes in COPD patients in primary care settings. A 6 weekly PRP did not give any additional benefits in patients already given tiotropium.

Aged↗
PubMed2005

A case of tetramine poisoning: a lethal rodenticide.

We report a fatal case of suicide presenting with convulsions and subsequently multi-organ failure. Rodenticide poisoning was not suspected until the next day when tetramine was detected in the patient's blood, urine, and food residues. Tetramine is a potent rodenticide with a rapid action and high mortality. The poison has been banned worldwide but is still readily available in Mainland China. Outbreaks of poisoning are reported frequently and doctors should be alert for this lethal toxin.

Bridged-Ring Compounds↗
PubMed2004

Protective effects of Danshensu from the aqueous extract of Salvia miltiorrhiza (Danshen) against homocysteine-induced endothelial dysfunction.

Homocysteine (Hcy) is a by-product of methionine metabolism. An imbalance of Hcy in the body may lead to hyperhomocysteinemia, a condition with elevated Hcy concentration in blood that may be one of the risk factors responsible for the development of several vascular diseases (thromboembolism, atherosclerosis, stroke, vascular diseases and dementia). Radix Salvia miltiorrhiza (Danshen), a well-known Chinese medicinal herb that can activate and improve blood microcirculation, is noticeable for its beneficial effect in treating cardiovascular diseases. The present study is to demonstrate the protective effect of Danshen extract against the homocysteine-induced adverse effect on human umbilical vein endothelial cell (HUVEC). Homocysteine (5 mM) not only decreased the cell viability but also caused the disruption of capillary-like structure formation in vitro. The protective effect of Danshen aqueous extract and its active compounds on endothelial cell function were demonstrated through an in vitro tube formation assay, which mimics the new blood vessel formation. To identify the active components in the aqueous extract of Danshen, the content was characterized by instrumental analysis using high performance liquid chromatography with diode array detector (DAD) and electrospray tandem mass spectrometry (ESI-MS/MS). Interestingly, Danshen extract and its pure compounds showed different effectiveness in protecting HUVEC against Hcy-induced injury according to the following descending order: Danshen aqueous extract, 3-(3,4-dihydroxy-phenyl)-2-hydroxy-propionic acid (Danshensu), protocatechuic acid, catechin and protocatechualdehyde. We believed that such findings might provide evidence in understanding the beneficial effects of Danshen on the cardiovascular system.

Benzaldehydes↗
PubMed2004

Use of antiretroviral therapy among HIV positive individuals living in British Columbia.

The objective of this study was to examine the level of antiretroviral use and characterize individuals accessing antiretroviral therapy in British Columbia. The study was conducted by the British Columbia Persons with AIDS Society and the British Columbia Centre for Excellence in HIV/AIDS. Self-administered questionnaires were mailed out to HIV-positive members from May to September of 2002. Comparisons of sociodemographic characteristics and disease status were made using Pearson's Chi2 and the Kruskal-Wallis test for continuous variables. A total of 764 (51%) HIV-positive participants returned the questionnaire. Of these, 80% reported ever using antiretroviral therapy and 64.5% indicated current use. Reasons for never taking antiretroviral therapy were high CD4 or doctor's advice (74/126; 59%), feeling healthy (50/126; 40%) and being afraid of side-effects (35/126; 28%). Those reporting current antiretroviral use were more likely to be older (p<0.001), white (p=0.01), male (p<0.001), gay or bisexual (p<0.001), graduated from high school (p=0.001), non-injecting drug user (IDU) (p<0.001) and earning a household income greater than CAN$10,000/year (p=0.003). IDU status and length of time since diagnosis remained significantly associated with antiretroviral use in multivariate models. The differences in current antiretroviral use by sociodemographic characteristics such as IDU suggest that the need remains to target marginalized populations in order to maximize the health benefits from antiretroviral therapy.

Adult↗
PubMed2004

Development and management of a radon assessment strategy suitable for underground railway tunnelling projects.

The construction of underground tunnels through radon-bearing rock poses a radiation health risk to tunnelling workers from exposure to radon gas and its radioactive decay products. This paper presents the development and practical application of a radon assessment strategy suitable for the measurement of radon in tunnelling work environments in Hong Kong. The assessment strategy was successfully evaluated on a number of underground railway tunnelling projects over a 3 y period. Radon measurements were undertaken using a combination of portable radon measurement equipment and track etch detectors (TEDs) deployed throughout the tunnels. The radon gas monitoring results were used to confirm that ventilation rates were adequate or identified, at an early stage, when further action to reduce radon levels was required. Exposure dose estimates based on the TED results showed that the exposure of tunnel workers to radon did not exceed 3 mSv per annum for the duration of each project.

Air Pollutants, Radioactive↗
PubMed2004

Effect of tai chi exercise on proprioception of ankle and knee joints in old people.

OBJECTIVES: To assess if tai chi, a traditional Chinese form of exercise, could improve proprioception in old people and if the effects of tai chi on proprioception are more evident than other exercise forms in the elderly. METHODS: By detecting the threshold of passive movement, ankle and knee joint kinaesthesis was measured in 21 elderly long term tai chi practitioners (TC group), 20 elderly long term swimmers/runners (S/R group), and 27 elderly sedentary controls (control group). RESULTS: Ankle joint kinaesthesis differed significantly among the three groups (p = 0.001). Subjects in the TC group could detect a significantly smaller amount of motion than those in the S/R group (p = 0.022) and control group (p = 0.001). No significant difference was found between the S/R group and the control group (p = 0.701). The threshold for detection of passive motion was significantly different in knee extension and flexion. For knee flexion, the TC group showed a significantly lower mean threshold for detection of passive motion than the control group (p = 0.026). There were no significant differences between the S/R group and control group (p = 0.312), or between the TC group and S/R group (p = 0.533). For knee extension, no significant difference was noted among the three groups (p = 0.597). CONCLUSIONS: The elderly people who regularly practiced tai chi not only showed better proprioception at the ankle and knee joints than sedentary controls, but also better ankle kinaesthesis than swimmers/runners. The large benefits of tai chi exercise on proprioception may result in the maintenance of balance control in older people.

Aged↗
PubMed2004

A panel study on the effects of a Chinese medicinal suppository, Vigconic VI-28, on insulin-like growth factor 1 and homocysteine in healthy men.

Changes in serum homocysteine (Hcy), often related to stroke and vascular dementia, are negatively correlated with changes in serum insulin-like growth factor 1 (IGF-1) and growth hormone (GH) replacement decreases Hcy levels in men with GH deficiency. Very little information on the effects of Chinese medicines on GH and Hcy is available in the literature published in English. In this study, the effects of a Chinese medicine suppository, Vigconic VI-28 (VI-28), consisting of concentrated extracts of a composite mixture of herbal materials, on serum IGF-1 and Hcy were studied. In vivo observations after treatment with Chinese medicines have often indicated changes in biochemical profiles of measurable parameters related to those changes in endocrine secretions. Thirty six healthy males (age 47-66) were under observation over a 16-week schedule after using VI-28 suppository from 0 to 12 weeks. Blood specimens were taken monthly (except at the end of week 8) for analysis of Hcy and IGF-1 levels. Compared with week 0, IGF-1 levels (192.5 +/- 66.4 ng/ml) were significantly elevated at week 4 (211.7 +/- 80.5, p < 0.05) and week 12 (226.6 +/- 95.2 ng/ml, p = 0.01). No significant changes were observed for Hcy for the whole cohort from week 0 to week 16. When the cohort was divided into 2 groups using a Hcy level of 13.0 micro mol/l as the cut-off, a significant (p < 0.05) difference in IGF-1 was observed between the 2 groups at week 12 only. The mean IGF-1 of 14 subjects with higher Hcy levels was lower than that of the 22 subjects with lower Hcy. We believe that VI-28 may exert a regulatory effect on the relationship between Hcy and IGF-1, at least in subjects with relatively low levels of Hcy. In addition, we also observed an apparent association of hyperhomocysteinemia (Hcy> or =13.0 micromol/l) with decreased IGF-1.

Aged↗