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Biomedical subjects

M F Chan

Publications and source records attributed to M F Chan.

At least 19 recordsLinked to original sources
PubMed2006

Investigating nurses' knowledge, attitudes, and skills patterns towards clinical management system: results of a cluster analysis.

To determine whether definable subtypes exist within a cohort of Hong Kong nurses as related to the clinical management system use in their clinical practices based on their knowledge, attitudes, skills, and background factors. Data were collected using a structured questionnaire. The sample of 242 registered nurses was recruited from three hospitals in Hong Kong. The study employs personal and demographic variables, knowledge, attitudes, and skills scale. A cluster analysis yielded two clusters. Each cluster represents a different profile of Hong Kong nurses on the clinical management system use in their clinical practices. The first group (Cluster 1) was labeled 'lower attitudes, less skilful and average knowledge' group, and represented 55.4% of the total respondents. The second group (Cluster 2) was labeled as 'positive attitudes, good knowledge but less skilful'. They comprised almost 44.6% of this nursing sample. Cluster 2 had more older nurses, the majority were educated to the baccalaureate or above level, with more than 10 years working experience, and they held a more senior ranking then Cluster 1. A clear profile of Hong Kong nurses may benefit healthcare professionals in making appropriate education or assistance to prompt the use of the clinical management system by nurses an officially recognized profession. The findings were useful in determining nurse-users' specific needs and their preferences for modification of the clinical management system. Such findings should be used to formulate strategies to encourage nurses to resolve actual problems following computer training and to increase the depth and breadth of nurses' knowledge, attitudes, and skills toward such system.

Adult↗
PubMed2006

The effectiveness of using a lipido-colloid dressing for patients with traumatic digital wounds.

This study compares the effect of a daily gauze dressing with that of a lipido-colloid dressing on the time taken to make up the dressing and efficacy of the management of traumatic digital wounds. This is a randomized controlled trial of 28 patients (16 experimental and 12 control) with injuries to their fingers and loss of tissue. The patients in the experimental and control groups were given a lipido-colloid dressing and a daily gauze dressing, respectively. The patients'wounds were assessed in terms of the size of the wound and the time it took for the wound to heal. The findings showed that patients in the experimental group had a faster recovery time from the healing of their wound than the control group (p= .024). The findings can help to establish an evidence-based practice in the management of traumatic digital wounds in clinical settings.

Adult↗
PubMed2005

Investigating spiritual care perceptions and practice patterns in Hong Kong nurses: results of a cluster analysis.

AIM: Nurses' spiritual care perceptions and practices are explored by identifying profiles of nurses studying in a part-time baccalaureate course in a local Hong Kong university. Relationships between nurses' spiritual care perceptions and their practices are explored. RESEARCH METHOD: Hundred and ninety three nurses completed a structured questionnaire. OUTCOME MEASURES: Spiritual care perceptions and practices. RESULTS: Two-step cluster analysis yielded three clusters. Clusters A, B, and C consisted of 15.0% (n = 29), 44.6% (n = 86), and 40.4% (n = 78), respectively. Cluster A nurses were characterized by relatively negative spiritual care perceptions and practices. Cluster C nurses reported positive perceptions, but negative practices; they mainly chose 'uncertain' for most items on both scales. Cluster B was a large group of nurses holding both positive spiritual care perceptions and practices. Significant differences towards spiritual care were found among clusters. Nurses' perceptions were significant positively correlated with practices (r = 0.62). High positive correlations were found between the two scales (r = 0.83) for nurses in Cluster A, for nurses in Clusters B and C, low positive correlations (r = 0.37) were found. CONCLUSION: Three clusters of Hong Kong nurses were differentiated. They showed differences in the level of their spiritual care perceptions and practices. Despite their level of spiritual care perceptions, nurses seldom incorporated spiritual care practices into their daily nursing care, and the level of spiritual care awareness of some nurses was low. Findings may be used to improve support of nurses, to ensure sensitive spiritual care in their daily practices, and to enhance nursing curricula.

Adult↗
PubMed2005

The effect of music therapy on postoperative pain, heart rate, systolic blood pressures and analgesic use following nasal surgery.

The prevalence of unrelieved postoperative pain is high and may lead to adverse effects including prolonged hospitalization and delayed recovery. Distraction may be an effective pain-relieving strategy, and can be implemented by several means including affective imaging, games, and possibly music. The aim of this study was to explore the effect of music therapy on postoperative pain. Fifty-seven patients (24 females, 33 males; mean +/- SD age 39.9 +/- 14.35 years [range 15 to 69 years] were matched for age and sex and then nonselectively assigned to either an experimental (n = 27) or a control (n = 30) group. Music was played intermittently to members of the experimental group during the first 24 hour postoperative period. Pain intensity was measured using the Pain Verbal Rating Scales (VRS). Significant decreases in pain intensity over time were found in the experimental group compared to the control group (p < 0.0001). In addition, the experimental group had a lower systolic blood pressure and heart rate, and took fewer oral analgesics for pain. These findings suggest that music therapy is an effective nonpharmacologic approach for postoperative pain management.

Acetaminophen↗
PubMed2004

Increased alpha 7 nicotinic acetylcholine receptor protein levels in Alzheimer's disease patients.

We compared the intact alpha7 nicotinic acetylcholine receptor (alpha7nAChR) protein levels in the peripheral blood leukocytes in 15 Alzheimer's disease (AD) patients and 13 normal elderly control subjects. Demographic data and Mini-Mental State Examination (MMSE) scores were obtained. Western blot analysis for alpha7nAChR protein levels in peripheral blood leukocytes was performed. There were no significant differences in sex and age between the AD and control groups. The mean MMSE score of the AD subjects was significantly lower than that of the normal control subjects (15.4 +/- 5.5 vs. 28.5 +/- 1.9 respectively; p < 0.001). The median value of normalized alpha7nAChR protein levels (optical density, arbitrary unit) of the AD group was significantly higher than that of the normal control group (0.6923 vs. 0.4803 respectively; p = 0.045, Mann-Whitney U test). The normalized alpha7nAChR protein levels showed a significant inverse correlation with the MMSE scores (Spearman rho = -0.45; p = 0.016; n = 28). Receiver Operating Characteristic curve analyses showed that the area under curve was 0.72 (95% CI 0.52- 0.87). If the cut-off of the alpha7nAChR protein level was >0.312, the sensitivity, specificity, positive predictive value and negative predictive value would be 80, 39, 60 and 63%, respectively. These findings showed that the alpha7nAChR protein levels would be a potentially useful diagnostic marker for AD.

Aged↗
PubMed2004

An experimentally confirmed statistical model on arm movement.

The purpose of this research work was to develop a methodology to model arm movement in normal subjects and neurologically impaired individuals through the application of a statistical modelling method. Thirteen subjects with Parkinson's disease and 29 normal controls were recruited to participate in an arm motor task. An infrared optoelectronic kinematic movement analysis system was employed to record arm movement at 50 times per second. This study identified the modified extended Freundlich model as one that could be used to describe this task. Results showed that this model fit the data well and that it has a good correspondence between the observed and the predicted data. However, verification of the model showed that the residuals contained a sizeable autocorrelation factor. The Cochrane and Orcutt method was applied to remove this factor, which improved the fit of the model. Results showed that Parkinson's disease subjects had a higher autocorrelation coefficient than the normal subjects for this task. A positive correlation (r(s) = 0.72, p < 0.001) was found between the Langton-Hewer stage and the autocorrelation coefficient of PD subjects. This finding suggests that if autocorrelation is positively correlated with disease progression, clinicians in their clinical practice might use the autocorrelation value as a useful indicator to quantify the progression of a subjects' disease. Significant differences in model parameters were seen between normal and Parkinson's disease subjects. The use of such a model to represent and quantify movement patterns provides an important base for future study.

Aged↗
PubMed2004

Enhancement of prosthetics and orthotics learning and teaching through e-Learning technology and methodology.

A Write-Once Publish-Everywhere model was used to create and deliver on-line clinical training and education for undergraduate prosthetics and orthotics students. This project consisted of three phases: developing multimedia learning and teaching tools, integrating these tools into the curriculum (combination of e-Learning and live practical sessions), and evaluating the outcomes. Video-based multimedia contents were captured and integrated with graphic, audio and text into a PowerPoint presentation software format. The web-based content was integrated into the WebCT platform for course management. Questionnaires were used to obtain student feedback on this e-Learning approach. Results were compared within the prosthetics and orthotics (P&O) programme, with other Health Sciences programmes, and overall with the University. P&O student responses were significantly higher than other groups for career relevance and problem solving. Qualitative feedback indicated that students appreciated the easy access, integrated and interactive approach of the text materials, concise PowerPoint presentation, demonstration video and the on-line case discussion via the WebCT platform. Educators appreciated the ability easily to maintain contents and publish the modules across multiple media without recreating the contents.

Adult↗
PubMed2003

Attitudes of Hong Kong Chinese to traditional Chinese medicine and Western medicine: survey and cluster analysis.

OBJECTIVES: To determine whether within a cohort of Hong Kong out-patients definable subtypes exist based on their attitudes to traditional Chinese medicine and Western medicine. DESIGN: Data were collected using a structured questionnaire. SETTING: The sample of 503 subjects was recruited at two local outpatient clinics in Hong Kong. MAIN OUTCOME MEASURES: The study employs demographic variables, illness status, the Chinese-Western Medical Belief Scale, trust of physicians and subjects' preferences on consultation fees, attitude of health care professional, efficacy of service and waiting time during consultation. RESULTS: A cluster analysis yielded three clusters based on their attitudes towards traditional Chinese and Western medicine. One cluster, 24% of the sample, is noted for being older, poorer, more likely to be female and to have chronic conditions; they are sceptical of western physicians. The second cluster (63% of the sample) is younger and have considerably more belief in Western than traditional Chinese medicine. The third group (14%) is intermediate in age and is noted for a marked faith in both forms of medicine. CONCLUSIONS: A clear profile of these attitudes of Hong Kong Chinese may benefit health care professionals in making appropriate patient-doctor relationships and planning patient care.

Adolescent↗
PubMed2002

A parameter optimization algorithm for intensity-modulated radiotherapy prostate treatment planning.

An iterative algorithm has been developed to analytically determine patient specific input parameters for intensity-modulated radiotherapy prostate treatment planning. The algorithm starts with a generic set of inverse planning parameters that include dose and volume constraints for the target and surrounding critical structures. The overlap region between the target volume and the rectum is used to determine the optimized target volume coverage goal. Sequential iterations are performed to vary the numerous parameters individually or in sets while other parameters remain fixed. A coarse grid search is first used to avoid convergence on a local maximum. Linear interpolation is then used to define a region for a fine grid search. Selected parameters are also tested for possible improvements in target coverage. In several representative test cases investigated the coverage of the planning target volume improved with the use of the algorithm while still meeting the clinical acceptability criteria for critical structures. The algorithm avoids time-consuming random trial and error variations that are often associated with difficult cases and also eliminates lengthy user learning curves. The methodology described in this paper can be applied to any treatment planning system that requires the user to select the input optimization parameters.

Algorithms↗
PubMed2001

Delivery of intensity-modulated radiation therapy with a conventional multileaf collimator: comparison of dynamic and segmental methods.

Intensity-modulated radiation therapy (IMRT) can be delivered with a conventional multileaf collimator (MLC), either in dynamic mode (DMLC) or in segmental mode (SMLC, also known as "step-and-shoot"). The advantage of DMLC is its ability to deliver the desired intensity profile produced by inverse planning with a high degree of fidelity. The SMLC method, on the other hand, resembles treatment with multiple static fields, and can be more easily verified. However, the use of SMLC requires that the desired profile be approximated by discrete levels of intensity, which may lead to degradation in the delivered dose distribution. Clearly, the results of SMLC delivery depend on the number of levels and the spatial resolution of the intensity distribution. In this work, we compare the DMLC method and the SMLC method employing different numbers of levels and different spatial resolutions. Three disease sites were studied: prostate, nasopharynx, and breast, with three cases for each. In general, a 5- to 10-level SMLC plan produced results comparable to that from a DMLC plan. The target coverage is improved by increasing the number of levels while critical organs are better protected with finer spatial resolutions. The beam-on-time (MUs) requirement for SMLC was approximately 20% less than DMLC, but the delivery time (in minutes) was about twice as long. Thus, the choice depends on many factors including machine capability, quality assurance, target coverage, critical organ protection, beam-on-time, delivery time, and other clinical considerations.

Breast Neoplasms↗
PubMed2001

The treatment of large extraskeletal chondrosarcoma of the leg: comparison of IMRT and conformal radiotherapy techniques.

Extraskeletal chondrosarcoma of the leg is a rare, malignant neoplasm with very few cases having been reported in the literature. In this study we investigate the possibility of using intensity modulated radiotherapy (IMRT) for this type of disease and demonstrate its advantages over conventional three-dimensional (3D) conformal treatment. A case was presented of a patient with extraskeletal chondrosarcoma of the lateral compartment of the leg in which the target volume was 50 cm in length and twisted around the surrounding bones. Both the 3D conformal plan and IMRT plan were designed using the Memorial Sloan-Kettering Cancer Center planning system. The IMRT plan produced a superior dose distribution to the patient as compared to the 3D conformal plan both in terms of dose conformity and homogeneity in the target volumes, and reduction of the maximum dose to the bone. The planning time of the IMRT plan was about 3-5 times shorter than that of the 3D conformal plan. It was demonstrated that the IMRT technique can be used not just for small tumors, but also for large and spiral-shaped tumors close to critical organs. The IMRT method requires less planning time, and provides better target coverage with more sparing of critical structures. When planning patients with multiple target volumes receiving different prescribed doses, the IMRT technique can more easily meet this requirement.

Adult↗
PubMed2001

The measurement of three dimensional dose distribution of a ruthenium-106 ophthalmological applicator using magnetic resonance imaging of BANG polymer gels.

The BANG (MGS Research Inc., Guilford, CT) polymer gel has been used as a dosimeter to determine the three-dimensional (3D) dose distribution of a ruthenium-106 (Ru-106) ophthalmologic applicator. An eye phantom made of the BANG gel was irradiated with the Ru-106 source for up to 1 h. The phantom and a set of calibration vials were scanned simultaneously in a GE 1.5 T MR imager using the Hahn spin-echo pulse sequence with a TR of 2000 ms and two TEs of 20 ms and 100 ms. The T(2) values were evaluated on a pixel-by-pixel basis using custom-built software on a DEC alpha workstation and converted to dose using calibration data. Depth doses and isodose lines of the Ru-106 eye-plaque were generated. It is concluded that the BANG gel dosimetry offers the potential for measuring the 3D dose distributions of an ophthalmologic applicator, with high spatial resolution and relatively good accuracy.

Brachytherapy↗
PubMed2001

Reduced rates of gene loss, gene silencing, and gene mutation in Dnmt1-deficient embryonic stem cells.

Tumor suppressor gene inactivation is a crucial event in oncogenesis. Gene inactivation mechanisms include events resulting in loss of heterozygosity (LOH), gene mutation, and transcriptional silencing. The contribution of each of these different pathways varies among tumor suppressor genes and by cancer type. The factors that influence the relative utilization of gene inactivation pathways are poorly understood. In this study, we describe a detailed quantitative analysis of the three major gene inactivation mechanisms for a model gene at two different genomic integration sites in mouse embryonic stem (ES) cells. In addition, we targeted the major DNA methyltransferase gene, Dnmt1, to investigate the relative contribution of DNA methylation to these various competing gene inactivation pathways. Our data show that gene loss is the predominant mode of inactivation of a herpes simplex virus thymidine kinase neomycin phosphotransferase reporter gene (HSV-TKNeo) at the two integration sites tested and that this event is significantly reduced in Dnmt1-deficient cells. Gene silencing by promoter methylation requires Dnmt1, suggesting that the expression of Dnmt3a and Dnmt3b alone in ES cells is insufficient to achieve effective gene silencing. We used a novel assay to show that missense mutation rates are also substantially reduced in Dnmt1-deficient cells. This is the first direct demonstration that DNA methylation affects point mutation rates in mammalian cells. Surprisingly, the fraction of CpG transition mutations was not reduced in Dnmt1-deficient cells. Finally, we show that methyl group-deficient growth conditions do not cause an increase in missense mutation rates in Dnmt1-proficient cells, as predicted by methyltransferase-mediated mutagenesis models. We conclude that Dnmt1 deficiency and the accompanying genomic DNA hypomethylation result in a reduction of three major pathways of gene inactivation in our model system.

DNA (Cytosine-5-)-Methyltransferase 1↗
PubMed2000

Replacement of the carboxylic acid group of prostaglandin f(2alpha) with a hydroxyl or methoxy substituent provides biologically unique compounds.

Replacement of the carboxylic acid group of PGF(2alpha) with the non-acidic substituents hydroxyl (-OH) or methoxy (-OCH(3)) resulted in an unexpected activity profile. Although PGF(2alpha) 1-OH and PGF(2alpha) 1-OCH(3) exhibited potent contractile effects similar to 17-phenyl PGF(2alpha) in the cat lung parenchymal preparation, they were approximately 1000 times less potent than 17-phenyl PGF(2alpha) in stimulating recombinant feline and human FP receptors. In human dermal fibroblasts and Swiss 3T3 cells PGF(2alpha) 1-OH and PGF(2alpha) 1-OCH(3) produced no Ca(2+) signal until a 1 microM concentration was exceeded. Pretreatment of Swiss 3T3 cells with either 1 microM PGF(2alpha) 1-OH or PGF(2alpha) 1-OCH(3) did not attenuate Ca(2+) signal responses produced by PGF(2alpha) or fluprostenol. In the rat uterus, PGF(2alpha) 1-OH was about two orders of magnitude less potent than 17-phenyl PGF(2alpha) whereas PGF(2alpha) 1-OCH(3) produced only a minimal effect. Radioligand binding studies on cat lung parenchymal plasma membrane preparations suggested that the cat lung parenchyma does not contain a homogeneous population of receptors that equally respond to PGF(2alpha)1-OH, PGF(2alpha)1-OCH(3), and classical FP receptor agonists. Studies on smooth muscle preparations and cells containing DP, EP(1), EP(2), EP(3), EP(4), IP, and TP receptors indicated that the activity of PGF(2alpha) 1-OH and PGF(2alpha) 1-OCH(3) could not be ascribed to interaction with these receptors. The potent effects of PGF(2alpha) 1-OH and PGF(2alpha) 1-OCH(3) on the cat lung parenchyma are difficult to describe in terms of interaction with the FP or any other known prostanoid receptor.

3T3 Cells↗
PubMed1999

Psychologic response of the edentulous patient after primary surgery for oral cancer: A cross-sectional study.

STATEMENT OF PROBLEM: Edentulous patients can have difficulty in tolerating dentures and this may lead to psychologic disturbance. The problem is potentially more severe for edentulous patients after primary surgery for oral cancer, where treatment can include composite resection and reconstruction, followed by adjuvant radiotherapy. PURPOSE: This study investigated the psychologic response and oral satisfaction of edentulous patients treated by surgery for oral squamous cell carcinoma, and to make a comparison to edentulous noncancer counterparts. METHODS AND MATERIAL: The cross-sectional study included patients who were alive and disease-free 2 to 3 years after primary surgery. Seventy patients underwent surgery at the Regional Maxillofacial Unit, Liverpool, in 1993 and 1994. Twenty-eight patients were disease-free; 26 completed questionnaires that included a general health questionnaire (GHQ), a body satisfaction scale, a self-esteem scale, an oral symptom checklist, and a denture satisfaction questionnaire. Comparison was made with 98 noncancer edentulous patients from the same unit. RESULTS: There were similarities in psychologic and oral satisfaction scores between the noncancer and cancer edentulous patients. Cancer patients reported lower self-esteem (P <.02). Cancer patients who were not rehabilitated with either conventional or implant-retained prostheses had significant psychologic morbidity as measured by the GHQ, self-esteem, and body satisfaction scales. Cancer patients with implant-retained overdentures reported greater satisfaction with their dentures compared with their counterparts who wore conventional dentures (P <.05). CONCLUSION: Edentulous cancer patients who do not achieve oral rehabilitation after surgery for oral cancer exhibited significant psychologic morbidity. Patients with implant-retained overdentures exhibited a tendency to adopt the same psychologic response with improved denture satisfaction as edentulous patients with conventional dentures, despite the former having more extensive disease that would otherwise make the provision of dentures much more difficult if implants were not used.

Aged↗
PubMed1999

Botulinum toxin injections for achalasia symptoms can approximate the short term efficacy of a single pneumatic dilation: a survival analysis approach.

OBJECTIVE: Botulinum toxin injection can induce a temporary symptomatic remission in some patients with achalasia, but the comparative utility of the approach is not fully known. This study used survival analysis methods to better understand the ability of single or repeated botulinum toxin injections to postpone the need for other treatments. METHODS: The response to botulinum toxin in 42 patients with idiopathic achalasia who had not received prior treatment was compared with the outcome in 26 consecutive patients who underwent initial treatment with pneumatic dilation. Survival analysis methods were employed using time to retreatment as the principal outcome measure. RESULTS: Retreatment (any type) was required in 50% of subjects at 265 days (0.73 yr) after the first botulinum toxin injection. In contrast, retreatment after initial pneumatic dilation was required in <40% of patients after 2 and 5 yr of follow-up. The curves became significantly separated (p < 0.05) within 1 yr after initial treatment. Of those treated solely with botulinum toxin injections, repeated as needed, only 46% required pneumatic dilation or surgery by 2 yr. Survival analysis curves for repeated injections and initial pneumatic dilation did not differ statistically at 1 or 2 yr (p = 0.5 and p = 0.4, respectively). Correlational analyses indicated that, of the clinical parameters tested, only the degree of dysphagia for liquids was useful in selecting the better responders to botulinum toxin injections, with lesser symptoms predicting longer time to retreatment. CONCLUSIONS: Botulinum toxin injections, repeated as needed, can approximate the benefits of a single pneumatic dilation for < or = 2 yr from the standpoint of usual factors that drive further management.

Botulinum Toxins, Type A↗
PubMed1998

The discovery and structure-activity relationships of nonpeptide, low molecular weight antagonists selective for the endothelin ET(B) receptor.

The systematic modification of the ETA selective N-(5-isoxazolyl)benzene-sulfonamide endothelin antagonists to give ETB selective antagonists is reported. The reversal in selectivity was brought about by substitution of the 4-position with aryl and substituted aryl groups. Of all the aromatic substituents studied, the para-tolyl group gave rise to the most active and selective ETB antagonist. Larger substituents caused a decrease in both ETB activity and selectivity. A similar trend was observed by substitution at the 5-position of the N-(5-isoxazolyl)-2-thiophenesulfonamide ETA receptor antagonists. The para-tolyl group was again found to be optimal for the ETB activity and selectivity. The structural features that were found to be favorable for binding to the ETB receptor, that is, the presence of a linear, conjugated pi-system of definite shape and size, have been successfully incorporated into the design of ETB selective polycyclic aromatic sulfonamides antagonists.

Animals↗