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Biomedical subjects

W M Chan

Publications and source records attributed to W M Chan.

At least 37 records · Page 2Linked to original sources
PubMed2001

Rhodopsin mutations in Chinese patients with retinitis pigmentosa.

AIM: To determine the pattern of rhodopsin mutations in Chinese retinitis pigmentosa (RP) patients. METHODS: The rhodopsin gene was examined in 101 RP patients and 190 controls from Hong Kong. RESULTS: Three coding changes were identified: Pro347Leu, Ala299Ser, and 5211delC. Each protein sequence alteration was found in one patient. Ala299Ser also existed in two controls. CONCLUSION: The C-terminal nonsense mutation may cause mis-sorting of rhodopsin protein. The finding of controls with Ala299Ser suggests this is only the third missense alteration reported that does not cause RP. The expected frequency of rhodopsin mutations in RP is <7% (2/101=2.0%, 95% confidence interval: 0.2%-7.0%).

Adult↗
PubMed2001

The role of telenursing in the provision of geriatric outreach services to residential homes in Hong Kong.

A residential nursing home in Hong Kong was linked to the community geriatric assessment team based in a regional hospital using videoconferencing equipment operating at 384 kbit/s. The feasibility of providing nursing services and their acceptability to users were evaluated over 12 months. There were 198 occupants of the nursing home and their mean age was 82 years (range 60-101). Services included patient education regarding the use of a metered dose inhaler, wound management and a falls prevention programme, together with assessment of clients' need for infirmary care and the risk of aspiration. The acceptability of the system to the clients and nursing home staff was also assessed. It was found that 89% of such services could be carried out via telemedicine, and only 11% required on-site visits. There was an increase in the proportion of patients correctly using inhalers as well as a reduction in the number of falls. More consultations were conducted by the nurse (an increase of 76% per month) and an additional 8.4 patients per month could be attended to by the nurse compared with 5 patients when on-site visits were used. Acceptability to clients and nursing home staff was good. The problem of lack of resources to support elderly residential care institutions makes service delivery via telemedicine appear economically attractive, as well as facilitating improvements in the quality of long-term care.

Accidental Falls↗
PubMed2000

Immunorestitution disease involving the innate and adaptive response.

Immunorestitution disease (IRD) is defined as an acute symptomatic or paradoxical deterioration of a (presumably) preexisting infection that is temporally related to the recovery of the immune system. We report the temporal sequence of events that led to IRD caused by Pneumocystis carinii and Aspergillus terreus in 2 human immunodeficiency virus (HIV)-negative patients soon after the recovery of adaptive and innate immunity, respectively, and we review episodes noted in the English-language literature that fit the definition of IRD (109 episodes in 107 patients). The median time from the recovery of neutrophil counts or termination of steroid therapy to the development of IRD was 8 days in cases of pulmonary aspergillosis (23 episodes) and hepatosplenic candidiasis (8) and 21 days for viral diseases such as hepatitis B (24) and viral pneumonitis (6). For IRD due to mycobacteriosis (27 episodes) and cryptococcosis (4) in HIV-positive patients, the median interval between the initiation of highly active antiretroviral therapy (HAART) and the onset of IRD was 11 days; for viral infections, including those due to cytomegalovirus (14), hepatitis B virus (1), and hepatitis C virus (2), the median interval was 42 days. As an emerging clinical entity, IRD merits further study to optimize treatment of immunosuppressed patients.

Adult↗
PubMed2000

Combined cataract extraction and submacular blood clot evacuation for globe perforation caused by retrobulbar injection.

A 45-year-old woman, originally scheduled for cataract surgery in the left eye, was referred for management of a globe perforation noticed after the retrobulbar injection of an anesthetic solution. There was a moderate degree of vitreous hemorrhage, and initial visual acuity was hand movement. A submacular blood clot of about 4-disc diameter was detected when the vitreous hemorrhage gradually cleared. One week after the incident, combined phacoemulsification, intraocular lens implantation, pars plana vitrectomy, and submacular clot removal using tissue plasminogen activator (tPA) as an adjunct were performed. Recovery was uneventful. At the last follow-up 6 months after surgery, best corrected visual acuity was 20/30.

Anesthesia, Local↗
PubMed2000

Raman spectroscopic study of oat globulin conformation.

Analysis of Raman spectra of oat globulin showed that extreme pH values caused an increase in the amide and C-H stretching band intensity, indicating changes in the secondary structures of the protein due to denaturation. Similar changes were observed when oat globulin was treated with chaotropic salts and several protein perturbants. Sodium dodecyl sulfate, beta-mercaptoethanol, and ethylene glycol also caused a shift in the amide III' band, suggesting a transition from beta-sheet to a random coil conformation. Heating at temperatures near the denaturation temperature of oat globulin led to increases in the amide and C-H band intensity, indicating unfolding of the protein. The data indicate that FT-Raman spectroscopy is suitable for studying the secondary structure of plant proteins such as oat globulin.

Avena↗
PubMed2000

Structural factors that determine the ability of adenosine and related compounds to activate the cardiac ryanodine receptor.

The effects of adenosine and adenine on the gating of native sheep cardiac ryanodine receptor (RyR) channels were investigated. By examining the mechanisms underlying channel activation and by using comparative molecular field analysis (CoMFA) we have investigated the structural features of adenine-based ligands involved in channel activation. In the presence of 10 microM cytosolic Ca(2+), adenosine and adenine both activate the channel but only to a level approximately 10 and 20% respectively of that of ATP indicating that both are partial agonists of low efficacy. Adenosine was able to antagonize the ATP-induced increase in open probability (Po) as expected for a partial agonist of low efficacy at the ATP sites on the cardiac RyR. GTP (100 microM - 10 mM) had no effect on channel gating indicating that the adenine ring structure is important for agonist activity at the ATP-sites on RyR. CoMFA revealed an extremely strong correlation between the structural features of the five ATP analogues and the ability to increase (Po). Our model indicates that the high efficacy of ATP results primarily from the large electrostatic field established by the ionized phosphate groups. Reducing the number of phosphate groups lowers the strength of this field, leading to ligands with lower efficacy. In addition, steric interactions between the alpha-phosphate and ribose moieties and the RyR are correlated with low Po.

Adenine↗
PubMed2000

The apolipoprotein E epsilon4 allele is unlikely to be a major risk factor of age-related macular degeneration in Chinese.

Apolipoprotein E (ApoE) is a major transporter of lipids and cholesterol in the nervous system. Age-related macular degeneration (ARMD), characterized by drusen containing lipids, was reported to show a lower frequency of the ApoE epsilon4 allele than control subjects. We sought to examine the association of this polymorphism with ARMD in Hong Kong Chinese. Among 98 ARMD subjects, the frequency of epsilon4 carriers showed a trend toward a decrease compared to controls, but it was not significant (11.2 vs. 15.0%, p < 0.52). The association of epsilon4 with an apparent reduced risk of ARMD was reported previously in the exudative form of the disease, however among 39 exudative ARMD patients there was also no significant difference in epsilon4 frequency (12.8%, p < 0.93). The lack of a statistically significant effect of epsilon4 may be due to the lower frequency of epsilon4 in Chinese than Europeans. Thus we cannot exclude a possible effect of this allele on ARMD risk, but we can conclude that this allele is likely not a major factor influencing ARMD risk in the Chinese.

Adult↗
PubMed1999

A comparative study on the efficacy of levofloxacin and ceftazidime in acute exacerbation of bronchiectasis.

A prospective randomized study was performed in order to compare the efficacy of oral levofloxacin, a new S- isomer of ofloxacin, with intravenous ceftazidime in the empirical treatment of acute exacerbations of bronchiectasis. Consecutive patients with acute exacerbation of bronchiectasis were recruited at a tertiary referral centre and were randomized to receive 10 days' treatment with either oral levofloxacin (300 mg b..d.) or ceftazidime (1 g i.v.t.d.). Body temperature, cough score, dyspnoea score, sputum purulence and volume and white blood cell and neutrophil count were assessed on day 1 and day 10. Thirty-five patients (mean age 61 yrs, 15 males) completed the study; 17 of these were in the levofloxacin group. There was no significant difference in the distribution of sputum pathogens or clinical parameters between the two groups at entry to and completion of the study. Both groups of patients showed significant improvement in 24-h sputum volume, sputum purulence score, cough score and dyspnoea score (p<0.001) but there was no significant difference between these two groups at entry to or on completion of the study (p>0.05). The results of this study suggest that oral administration of levofloxacin is as effective as parenteral ceftazidime in the empirical treatment of exacerbations in bronchiectasis.

Acute Disease↗