Biomedical subjects

Y K Wong

Publications and source records attributed to Y K Wong.

At least 19 recordsLinked to original sources

PubMed2005

A community-based exercise programme for older persons with knee pain using telemedicine.

We explored the feasibility and efficacy of an exercise programme for elderly people with knee pain conducted via videoconferencing. Twenty-two community-dwelling subjects aged 60 years or above with knee pain were recruited from two community centres in Hong Kong. A 12-week exercise programme, including strengthening and balance training, was given via videoconferencing to subjects at both centres, in conjunction with a home-based exercise programme. The outcome measures included the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), quadriceps muscle strength, Berg's Balance Scale (BBS) and subjects' degree of acceptance of videoconferencing. Twenty subjects completed the 12-week programme and significant improvements occurred in all domains of the WOMAC score (P <0.003). There was a 44% and a 13% increase in quadriceps muscle strength (P <0.001) and BBS (P <0.001), respectively. Over 80% of the elderly subjects who joined the programme agreed or strongly agreed about all aspects of using videoconferencing. Most of them felt that the system was user-friendly and convenient. Videoconferencing appears to be a useful method of delivering a resistance-training programme for community-dwelling elderly persons with knee pain.

Aged↗

PubMed2004

Model-based fault diagnosis in continuous dynamic systems.

Traditional fault detection and isolation methods are based on quantitative models which are sometimes difficult and costly to obtain. In this paper, qualitative bond graph (QBG) reasoning is adopted as the modeling scheme to generate a set of qualitative equations. The QBG method provides a unified approach for modeling engineering systems, in particular, mechatronic systems. An input-output qualitative equation derived from QBG formalism performs continuous system monitoring. Fault diagnosis is activated when a discrepancy is observed between measured abnormal behavior and predicted system behavior. Genetic algorithms (GA's) are then used to search for possible faulty components among a system of qualitative equations. In order to demonstrate the performance of the proposed algorithm, we have tested it on a laboratory scale servo-tank liquid process rig. Results of the proposed model-based fault detection and diagnosis algorithm for the process rig are presented and discussed.

Journal Article↗

PubMed2003

On-line lower-order modeling via neural networks.

This paper presents a novel method to determine the parameters of a first-order plus dead-time model using neural networks. The outputs of the neural networks are the gain, dominant time constant, and apparent time delay. By combining this algorithm with a conventional PI or PID controller, we also present an adaptive controller which requires very little a priori knowledge about the plant under control. The simplicity of the scheme for real-time control provides a new approach for implementing neural network applications for a variety of on-line industrial control problems. Simulation and experimental results demonstrate the feasibility and adaptive property of the proposed scheme.

Algorithms↗

PubMed2003

Improving the positive predictive value of exercise testing in women.

OBJECTIVE: To identify exercise test variables that can improve the positive predictive value of exercise testing in women. DESIGN: Cohort study. SETTING: Regional cardiothoracic centre. SUBJECTS: 1286 women and 1801 men referred by primary care physicians to a rapid access chest pain clinic, of whom 160 women and 406 men had ST depression of at least 1 mm during exercise testing. The results for 136 women and 124 men with positive exercise tests were analysed. MAIN OUTCOME MEASURES: The proportion of women with a positive exercise test who could be identified as being at low risk for prognostic coronary heart disease and the resulting improvement in the positive predictive value. RESULTS: Independently of age, an exercise time of more than six minutes, a maximum heart rate of more than 150 beats/min, and an ST recovery time of less than one minute were the variables that best identified women at low risk. One to three of these variables identified between 11.8% and 41.2% of women as being at low risk, with a risk for prognostic disease of between 0-11.5%. The positive predictive value for the remaining women was improved from 47.8% up to 61.5%, and the number of normal angiograms was potentially reducible by between 21.1-54.9%. By the same criteria, men had higher risks for prognostic disease. CONCLUSIONS: A strategy of discriminating true from false positive exercise tests is worthwhile in women but less successful in men.

Age Factors↗

PubMed2003

Relationships of perceived benefits and barriers to physical activity, physical activity participation and physical fitness in Hong Kong female adolescents.

AIM: Previous studies that examined participation in physical activity suggested that female adolescents were less active compared with males. However, the relationship between physical fitness, physical activity participation, and perceived benefits and barriers for physical activity to adolescents, irrespective of gender, has not been made clear. This study examines the association of these factors in female adolescents. METHODS: Physical activity participation and perceived benefits and barriers to physical activity were determined in 206 secondary school female subjects (aged 11 to 18) using a validated questionnaire. RESULTS: Subjects with a correct concept about optimal physical activity participation to maintain health engaged in an activity level higher than the group without a correct concept (t=2.37, p=0.02). A significant correlation was established between the physical activity participation with "health" (r=0.22, p<0.001) and "body image" (r=0.17, p=0.02) in the perceived benefit category. The individual factor, "make me feel better in general" in the "health" category (p=0.04) and the intention to participate (p<0.001) were shown to be significant predictors for physical activity participation. The combined effects of the regression model explained 35.9% of the variance in participation in physical activity. CONCLUSION: Policies to support regular physical activity participation at school and out-of-school should be strategically developed and promoted, highlighting the promotion of health benefits in exercise and the reinforcement of initial intent towards exercise.

Adolescent↗

PubMed2002

Fusion of qualitative bond graph and genetic algorithms: a fault diagnosis application.

In this paper, the problem of fault diagnosis via integration of genetic algorithms (GA's) and qualitative bond graphs (QBG's) is addressed. We suggest that GA's can be used to search for possible fault components among a system of qualitative equations. The QBG is adopted as the modeling scheme to generate a set of qualitative equations. The qualitative bond graph provides a unified approach for modeling engineering systems, in particular, mechatronic systems. In order to demonstrate the performance of the proposed algorithm, we have tested the proposed algorithm on an in-house designed and built floating disc experimental setup. Results from fault diagnosis in the floating disc system are presented and discussed. Additional measurements will be required to localize the fault when more than one fault candidate is inferred. Fault diagnosis is activated by a fault detection mechanism when a discrepancy between measured abnormal behavior and predicted system behavior is observed. The fault detection mechanism is not presented here.

Air Movements↗

PubMed2001

Establishment and characterization of an oral melanoma cell line (ME).

A new cell line, ME, has been established from a melanoma of the palatal mucosa. The cultured monolayer of cells was fusiform and melanin-producing. The cells were highly tumorigenic and metastatic in nude mice. The xenographic tumors resembled the original tumor in morphology, melanin production, and the expression of S-100 and HMB-45 antigens. The metaphase karyotype of ME indicated multiple aberrations of chromosomes 2, 3, 5, 7-11, 13, 19, 21 and X. A homozygous loss of the p16/MTS1 gene during the establishment of ME correlated with karyotypic evidence of chromosome 9 abnormalities. Absence of nm23 protein expression and elevated expression of CD44 protein (indicative of metastatic phenotypes) were demonstrated in primary and xenographic tumors. ME cells could be valuable in developing novel therapeutic strategies for oral melanoma.

Aged↗

PubMed2001

The association between deaths from myocardial infarction and household size in England and Wales.

BACKGROUND: Chronic infection with organisms such as Chlamydia pneumoniae is thought to cause coronary heart disease. We investigated whether myocardial infarction deaths are associated with large household size and overcrowding, as these are factors that may facilitate the transmission of infection. DESIGN: Ecological study of England and Wales. METHODS: Population data were obtained from the 1991 National Census and mortality data were obtained from the Office of National Statistics. For various categories of household size and overcrowding, we calculated mortality rates standardized for age, sex and deprivation. RESULTS: Standardized mortality rates for acute respiratory infections were associated with household size and overcrowding, while rates for myocardial infarction and gastric carcinoma, both putatively associated with chronic infection, were associated with household size. For combined deaths from causes other than myocardial infarction, there were small associations with household size and overcrowding. In the case of myocardial infarction, the association was generally strongest in the age group 45-54.9 years. For this age group, the standardized mortality rate ratio for the category of largest size household was 2.7 in the year 1991. CONCLUSIONS: There is an association between household size and mortality from myocardial infarction. Chronic infection is a possible cause.

Adult↗

PubMed2000

Association of aberrant p53 and p21(WAF1) immunoreactivity with the outcome of oral verrucous leukoplakia in Taiwan.

The expression of p53 and p21WAF1 in 53 oral verrucous leukoplakias (OVLs), mostly non-dysplastic lesions, was investigated to ascertain the role of such events in malignant conversion. Immunohistochemical analysis revealed aberrant p53 and p21WAF1 immunoreactivity in 51% (27 cases) and 75% (40 cases), respectively. After an average follow-up period of three and a half years, histopathological examination revealed that 22 (42%) cases had developed oral squamous cell carcinoma (OSCC), 14 (26%) cases had undergone recurrence, and 17 (32%) cases were free of disease. The oncogenic potential of this subset of premalignant lesions warrants attention. A significant difference in the frequency of OSCC progression/recurrence was noted in lesions bearing aberrant immunoreactivity of either p53 (93% vs 42%; P=0.00008) or p21WAF1 (80% vs 32%; P=0.002) in comparison with lesions without immunoreactivity. This study suggested that the aberrant immunoreactivity of p53 and p21WAF1 may represent important alterations of OVL and could affect the outcome of this lesion.

Adult↗

PubMed2000

Alterations of p16/MTS1 gene in oral squamous cell carcinomas from Taiwanese.

To determine the alterations of the p16/MTS1 gene in oral squamous cell carcinoma (OSCC), we examined in Taiwanese patients the mutation, deletion and methylation of p16/MTS1 in primary OSCCs associated mostly with betel quid (BQ)/tobacco use. Among 110 tumors undergoing mutational analyses, seven (6%) showed mutations in exon 2 or the intron 1/exon 2 splice site. All but one mutation disrupted the encoded proteins. Base transitions represented the vast majority (6/7) of the mutations identified in BQ/tobacco consuming subjects. It was noted that 15/56 (27%) tumors examined by restriction fragment methylation analysis revealed a significant level of methylation in different loci of exon 1 as compared with the respective non-cancerous tissue. Mutation of p16/MTS1 was exclusively identified in carcinomas of buccal mucosa, whereas methylation of the p16/MTS1 promoter region occurred preferentially in carcinomas of the tongue (54%) rather than at other sites (22%). Homozygous deletion was not found in 56 paired samples examined, nor was hemizygous deletion indicated in 12 informative cases. The results indicated aberrant methylation and mutation as the molecular abnormality of p16/MTS1 in the OSCC from Taiwanese.

Adult↗

PubMed2000

Establishment and characterization of a cell line (HCDB-1) derived from a hamster buccal pouch carcinoma induced by DMBA and Taiwanese betel quid extract.

This study identified that the carcinogenesis of hamster buccal pouch (HBP) induced by 7,12-dimethylbenz[a]anthracene (DMBA) was greatly enhanced (18 folds) by a combination treatment with Taiwanese betel quid (BQ) extract. A new cell line, HCDB-1, has been established from induced carcinomas. The cultured monolayer cells were epithelioid in shape with irregular nuclei. They demonstrated abundant cytokeratin and tonofilaments; however, ultrastructural well-organized desmosomes were lacking. The HCDB-1 cell exhibited population doubling in 19 h and was highly tumorigenic in nude mice. A C-->T transition at codon 141 (Ala to Val) of the p53 gene was detected in this cell. This mutation is equivalent to a specific temperature-sensitive mouse p53Ala135Val mutant that causes transformation by shifting to 37.5 degrees C. HCDB-1 is the first cell line established from the HBP model of oral carcinogenesis induced by DMBA/Taiwanese BQ extract. It might be valuable for exploring the molecular pathogenesis of oral cancer.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed1999

Circulating Chlamydia pneumoniae DNA as a predictor of coronary artery disease.

OBJECTIVE: To determine whether current vascular Chlamydia pneumoniae (CPn) infection as diagnosed by circulating CPn DNA is more common in subjects with coronary artery disease (CAD). BACKGROUND: Serological, pathological and animal studies have associated CPn with CAD and preliminary trials suggest antibiotics may prevent adverse coronary events. C. pneumoniae is thought to disseminate systemically within macrophages. We therefore detected CPn DNA in blood to determine whether its presence was a predictor of CAD. METHODS: One thousand, two hundred and five subjects attending for diagnostic and interventional coronary arteriography were recruited. The mononuclear cell layer and platelets were separated from collected blood and the polymerase chain reaction (PCR) was used to detect CPn DNA. RESULTS: Circulating CPn DNA was found in 8.8% of 669 men with CAD compared with 2.9% of 135 men with normal coronary arteries (odds ratio [OR] 3.2, 95% confidence interval [CI] 1.1-8.9). In men with CAD, those with CPn DNA had higher mean platelet counts than those without CPn DNA. Monocyte counts and indirect fibrinogen levels were also raised but not significantly so. By contrast, no association of circulating CPn DNA and CAD was seen in women. CONCLUSIONS: Circulating CPn DNA is a predictor of CAD in men. Unlike serology, it is a specific indicator of current infection and is a means of identifying subjects who may potentially benefit from antichlamydial therapy.

Aged↗

PubMed1999

Risk factors for coronary heart disease and acute-phase proteins. A population-based study.

AIMS: Circulating levels of C-reactive protein and serum amyloid A protein increase markedly, and albumin levels fall, during the acute-phase response to tissue injury, infection and inflammation. Some acute-phase proteins have been associated with increased risks of coronary heart disease in long-term prospective studies. The aim of the present study was to determine whether circulating concentrations of C-reactive protein, albumin and serum amyloid A protein are correlated with one another, standard vascular risk factors, markers of persistent infection, or indicators of socio-economic status. METHODS AND RESULTS: We report a cross-sectional study of 704 individuals without a history of coronary heart disease from five general practices in Bedfordshire, U.K. Plasma levels of C-reactive protein and serum amyloid A protein were strongly associated with each other (2 P<0.00001) and inversely related to levels of serum albumin (2 P<0.00001). There were highly significant associations of plasma C-reactive protein concentrations with cigarette smoking and obesity (2 P<0.00001 for each). Serum albumin levels were strongly associated with blood pressure (2 P<0.0001) and plasma lipids (2 P<0.001), and concentrations of serum amyloid A protein were strongly correlated with obesity (2 P<0.0001). CONCLUSION: Previously reported long-term prospective studies have found an increased risk of coronary heart disease of about 50% in people with raised baseline levels of plasma C-reactive protein or low albumin. The strong cross-sectional associations we have found between levels of these proteins with each other and with concentrations of serum amyloid A protein suggest that some underlying process related to inflammation is likely to be of relevance to the causation of disease. Further studies are needed to determine if the strong associations of plasma levels of C-reactive protein with cigarette smoking and obesity indicate that this particular protein can mediate some of the effects of those risk factors on coronary heart disease.

Acute-Phase Proteins↗

PubMed1999

Surgical outcome of traumatic intracranial hematoma at a regional hospital in Taiwan.

BACKGROUND: To report the experience in the management of 489 consecutive patients with traumatic intracranial hematoma and determine the prognostic factors. METHODS: All patients were classified into three groups based on the number of operations for each case. A total of 538 operations were performed for evacuation of 720 intracranial hematomas. RESULTS: The most common cause of injury was motor vehicular traffic crashes (68.7%) and most victims were motorcyclists (40.1%). The most common type of lesion was acute epidural hematoma (31.0%). The overall mortality rate was 9.6%, and the complication rate was 11.2%. Follow-up assessment of 480 patients revealed that 270 (56.2%) patients made a good recovery, 99 (20.6%) were moderately disabled, 32 (6.7%) were severely disabled, 21 (4.4%) were vegetative, and 58 (12.1%) had died. CONCLUSION: The surgical outcome was significantly correlated with the score of the Glasgow Coma Scale, pupillary reactivity, number of operations, and type of lesion.

Adolescent↗

PubMed1999

Telomerase activity and in situ telomerase RNA expression in oral carcinogenesis.

To investigate the role of telomerase in oral carcinogenesis, we assayed telomerase activity in various oral tissues by a modified telomeric repeat amplification protocol (TRAP) analysis. Also, using digoxigenin-labeled probes, we measured the in situ expression of human telomerase RNA component (hTR) in paired oral squamous cell carcinomas (OSCC) and adjacent non-cancerous matched tissue (NCMT). We detected telomerase activity in three OSCC cell lines, but not in primary oral keratinocytes. In patient samples, most OSCC (36/42, 86%) and oral premalignant lesions (8/12, 67%) possessed telomerase activity. In addition, 6 of 27 (22%) NCMT contained weak telomerase activity. In situ hybridization showed that hTR was expressed in almost all OSCC (23/27, 85%) as well as in the majority of NCMT (20/25, 80%). In most cases, accumulation of hTR was observed both in the nucleus and cytoplasm of epithelial cells. A correlation between hTR expression and more advanced tumor grade was observed. The appearance of telomerase activation and hTR expression during oral carcinogenesis was different. This study indicates that the activation of telomerase is an early and frequent event in OSCC.

Adult↗

PubMed1999

Chlamydia pneumoniae and atherosclerosis.

OBJECTIVE: To review the literature for evidence that chronic infection with Chlamydia pneumoniae is associated with atherosclerosis and acute coronary syndromes. DATA SOURCES: MEDLINE and Institute of Science and Information bibliographic databases were searched at the end of September 1998. Indexing terms used were chlamydi*, heart, coronary, and atherosclerosis. Serological and pathological studies published as papers in any language since 1988 or abstracts since 1997 were selected. DATA EXTRACTION: It was assumed that chronic C pneumoniae infection is characterised by the presence of both specific IgG and IgA, and serological studies were examined for associations that fulfilled these criteria. Pathological studies were also reviewed for evidence that the presence of C pneumoniae in diseased vessels is associated with the severity and extent of atherosclerosis. DATA SYNTHESIS: The majority of serological studies have shown an association between C pneumoniae and atherosclerosis. However, the number of cases in studies that have reported a positive association when using strict criteria for chronic infection is similar to the number of cases in studies which found no association. Nevertheless, the organism is widely found in atherosclerotic vessels, although it may not be at all diseased sites and is not confined to the most severe lesions. Rabbit models and preliminary antibiotic trials suggest that the organism might exacerbate atherosclerosis. CONCLUSION: More evidence is required before C pneumoniae can be accepted as playing a role in atherosclerosis. Although use of antibiotics in routine practice is not justified, large scale trials in progress will help to elucidate the role of C pneumoniae.

Acute Disease↗

PubMed1999

The species specificity of the microimmunofluorescence antibody test and comparisons with a time resolved fluoroscopic immunoassay for measuring IgG antibodies against Chlamydia pneumoniae.

AIMS: To examine the species specificity of the microimmunofluorescence test (MIF) and assess a time resolved fluoroscopic immunoassay (TRIA) for measuring IgG antibodies to C pneumoniae. METHODS: Sera from 1020 subjects were tested by MIF for IgG, IgM, and IgA antibodies to C pneumoniae, C trachomatis, and C psittaci; 501 serum samples were also tested by TRIA for IgG antibodies to C pneumoniae. RESULTS: C pneumoniae antibody titres as measured by MIF were correlated with those for C psittaci and trachomatis. It was estimated that on average, one third of the twofold dilution steps that make up the final C pneumoniae antibody titre may be due to cross reacting genus specific antibody. The results of TRIA correlated well with those of MIF. In 75% of cases, the TRIA result predicted a three titre range within which the actual MIF result would fall. CONCLUSIONS: MIF does not appear to be as species specific as claimed. TRIA is unlikely to be as specific but as it is completely objective, easier to perform, amenable to automation, and gives reproducible results, it is a rapid and useful method for comparing populations.

Aged↗

PubMed1999

Intracerebral hemorrhage caused by cerebral amyloid angiopathy: a case report.

Cerebral amyloid angiopathy (CAA) accounts for approximately 10% of spontaneous intracerebral hemorrhages (ICH), and typically occurs in the cortex and subcortical white matter. It is characterized by the deposition of amyloid fibrils in the leptomeningeal, cortical and subcortical arteries. Pathologically, amyloid is stained pink with Congo red and shows yellow-green birefringence when viewed under polarized light. Although there have been many reports of CAA in the literature, it has rarely been described in Taiwan. This is the report of a case of a 75-year-old man with ICH caused by CAA. The postoperative course was uneventful. The incidence of this disease increases with age. The authors, therefore, suggest conducting a brain biopsy and special stain for CAA in each operative case of spontaneous ICH, especially in the elderly.

Aged↗