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Biomedical subjects

Vivian Chan

Publications and source records attributed to Vivian Chan.

27 records · Page 2Linked to original sources
PubMed2004

Association of novel single nucleotide polymorphisms in the calcium channel alpha 1 subunit gene (Ca(v)1.1) and thyrotoxic periodic paralysis.

Thyrotoxic (hypokalemic) periodic paralysis (TPP) is a frequent complication of thyrotoxicosis among Chinese men. To determine the genetic association of TPP, we studied 97 male TPP patients, 77 Graves' disease patients without TPP, and 100 normal male subjects. Mutations of the voltage-dependent calcium channel (Ca(v)1.1), sodium channel (Na(v)1.4), and potassium channel (K(v)3.4), and association of the microsatellite markers on chromosome 1 in the region of the Na/K-ATPase subunits alpha1, alpha2, and beta1 were studied. None of the TPP patients carried the known mutations in Ca(v)1.1, Na(v)1.4, and K(v)3.4 genes. There was no association of TPP with the microsatellite markers that mapped to 1p13, 1q21-23, and 1q22-25. We detected 12 single nucleotide polymorphisms (SNPs) in Ca(v)1.1 in our population, of which three were novel. Significant differences in the SNP genotype distribution between TPP compared with Graves' disease controls and normal controls were seen at the 5' flanking region nucleotide (nt) -476 (P = 0.02), intron 2 nt 57 (P < 0.01), and intron 26 nt 67 (P < 0.001). Because these SNPs lie at or near the thyroid hormone responsive element, it is possible that they may affect the binding affinity of the thyroid hormone responsive element and modulate the stimulation of thyroid hormone on the Ca(v)1.1 gene.

5' Flanking Region↗
PubMed2004

A new cross-over region for hemogloboin-Lepore-Hollandia.

Hb Lepore-Hollandia, identified in a Thai patient, was found to be due to a new cross-over between IVS1-nt 42 and nt 56 of the delta- and beta-globin genes. This differs from a previous case which crossed-over between codon 22 and IVS1-nt 16. Two independent homologous unequal cross-over events account for these two Lepore-Hollandia genes.

Female↗
PubMed2003

Bioelectronic DNA detection of human papillomaviruses using eSensor: a model system for detection of multiple pathogens.

BACKGROUND: We used human papillomaviruses (HPV) as a model system to evaluate the utility of a nucleic acid, hybridization-based bioelectronic DNA detection platform (eSensor) in identifying multiple pathogens. METHODS: Two chips were spotted with capture probes consisting of DNA oligonucleotide sequences specific for HPV types. Electrically conductive signal probes were synthesized to be complementary to a distinct region of the amplified HPV target DNA. A portion of the HPV L1 region that was amplified by using consensus primers served as target DNA. The amplified target was mixed with a cocktail of signal probes and added to a cartridge containing a DNA chip to allow for hybridization with complementary capture probes. RESULTS: Two bioelectric chips were designed and successfully detected 86% of the HPV types contained in clinical samples. CONCLUSIONS: This model system demonstrates the potential of the eSensor platform for rapid and integrated detection of multiple pathogens.

Biosensing Techniques↗
PubMed2003

Family experience caring for terminally ill patients with cancer in Hong Kong.

In this study, 24 family caregivers of terminally ill patients participated in in-depth interviews regarding their experiences of giving care. The data were analyzed using grounded theory qualitative method. Commitment emerged as the precondition of the caregiving process. The caregivers did not perceive the work of caring as a burden. Rather, they felt that despite any personal hardships, what they were doing was important to their loved ones and therefore meaningful to them as caregivers. The components of commitment can be described as relational commitment, the act of showing love, and determination. The process of caregiving includes four phases: 1) holding onto hope for a miracle, 2) taking care, 3) preparing for death, and 4) adjusting to another phase of life. A patient-caregiver relationship, Confucian concepts of yi (appropriateness or rightness), and filial duty are reflected in the process of caregiving. Consequences of the process include finding meaning in life and peace of heart and mind. The emotional aspect of the caregiving experience can be described as an intense emotional experience filled with feelings of hope and hopelessness, guilt, fear, and regret. As a result of the caregiving experience, most participants found they have had a change of worldviews and treasure their lives. Findings show a significant need for interventions at each phase of the caregiving process designed to provide effective and culturally sensitive support and affirmation to family members as they care for their loved ones with terminal illnesses.

Adaptation, Psychological↗
PubMed2003

Bioelectronic sensor technology for detection of cystic fibrosis and hereditary hemochromatosis mutations.

CONTEXT: Bioelectronic sensors, which combine microchip and biological components, are an emerging technology in clinical diagnostic testing. An electronic detection platform using DNA biochip technology (eSensor) is under development for molecular diagnostic applications. Owing to the novelty of these devices, demonstrations of their successful use in practical diagnostic applications are limited. OBJECTIVE: To assess the performance of the eSensor bioelectronic method in the validation of 6 Epstein-Barr virus-transformed blood lymphocyte cell lines with clinically important mutations for use as sources of genetic material for positive controls in clinical molecular genetic testing. Two cell lines carry mutations in the CFTR gene (cystic fibrosis), and 4 carry mutations in the HFE gene (hereditary hemochromatosis). DESIGN: Samples from each cell line were sent for genotype determination to 6 different molecular genetic testing facilities, including the laboratory developing the DNA biochips. In addition to the bioelectronic method, at least 3 different molecular diagnostic methods were used in the analysis of each cell line. Detailed data were collected from the DNA biochip output, and the genetic results were compared with those obtained using the more established methods. RESULTS: We report the successful use of 2 applications of the bioelectronic platform, one for detection of CFTR mutations and the other for detection of HFE mutations. In all cases, the results obtained with the DNA biochip were in concordance with those reported for the other methods. Electronic signal output from the DNA biochips clearly differentiated between mutated and wild-type alleles. This is the first report of the use of the cystic fibrosis detection platform. CONCLUSIONS: Bioelectronic sensors for the detection of disease-causing mutations performed well when used in a "real-life" situation, in this case, a validation study of positive control blood lymphocyte cell lines with mutations of public health importance. This study illustrates the practical potential of emerging bioelectronic DNA detection technologies for use in current molecular diagnostic applications.

Base Sequence↗
PubMed2002

A genetic locus for adolescent idiopathic scoliosis linked to chromosome 19p13.3.

Adolescent idiopathic scoliosis (AIS) is one of the most common orthopedic disorders, affecting up to 4% of schoolchildren worldwide. We studied seven unrelated multiplex families of southern Chinese descent with AIS, consisting of 25 affected members. A genomewide scan with >400 fluorescent microsatellite markers was performed. Multipoint linkage analysis by GENEHUNTER revealed significant linkage of the abnormal phenotype to the distal short arm of chromosome 19, with both a maximum multipoint LOD score and a nonparametric LOD score of 4.93. Two-point linkage analysis by MLINK gave a LOD score of 3.63 (recombination fraction theta[m=f]=0.00) at D19S216. Further high-density mapping and informative recombinations defined the AIS critical region in the vicinity of D19S216, flanked by D19S894 and D19S1034, spanning 5.2 cM on the sex-averaged genetic map on chromosome 19p13.3.

Adolescent↗
PubMed2002

Perception of empowerment by family caregivers of patients with a terminal illness in Hong Kong.

The purpose of this study is to provide an in-depth description of the nurse-facilitated empowering experiences of family caregivers of terminally ill patients in Hong Kong. Data were collected through in-depth interviews with 24 family caregivers of patients with terminal cancer. Grounded theory strategies served as the basis for data collection and analysis. Data were analysed in terms of the strategies, consequences, and interactions involved in the empowering experience. Themes included establishing an engaged relationship; providing information, knowledge and skills; affirming self-worth; and giving reassurance that the patient is under good care. The consequences of empowerment included a trusting relationship, having confidence to carry out caregiving tasks, acceptance of patient's death, sustained self-worth and feeling peace at heart. The focus of empowering experiences was related to the quality of life of the dying patients. Family caregivers require information, education, encouragement and support, and nurses are in an ideal position to meet this need. Fundamental in the empowering process is the formation of a trusting relationship and as a result the caregivers feeling they are not being abandoned or left alone in the caring process. The results of this study can help nurse interact more effectively with family caregivers, giving them direction for effective nursing practice when caring for patients with a terminal illness.

Caregivers↗
PubMedDate not supplied

Can defects in transferrin receptor 2 and hereditary hemochromatosis genes account for iron overload in HbH disease?

Iron overload was found to be the major cause of disability in Chinese HbH disease patients although they were not on regular blood transfusion. The transferrin receptor 2 (TFR2) and hereditary hemochromatosis (HFE) genes were examined to see if inheritance of these gene defects may be a possible cause of iron overload in 45 HbH patients. A novel intronic (IVS6 (+6) T-->A) mutation of the TFR2 gene was identified in one patient, and six others were found to carry a known missense mutation (exon 5, I238M) that was also present in one normal control subject. One HbH patient and one normal control carried the H63D mutation of the HFE gene. Since only eight out of 45 iron-overloaded HbH patients carry a defect in the TFR2 or HFE gene in the heterozygote state and their iron loading status was comparable to the matched controls without such defects, it would appear that the accumulation of excess iron in HbH disease is more likely a result of increase dietary absorption secondary to ineffective erythropoiesis.

Alleles↗