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Biomedical subjects

W W Yan

Publications and source records attributed to W W Yan.

16 recordsLinked to original sources
PubMed2003

Coronavirus as a possible cause of severe acute respiratory syndrome.

BACKGROUND: An outbreak of severe acute respiratory syndrome (SARS) has been reported in Hong Kong. We investigated the viral cause and clinical presentation among 50 patients. METHODS: We analysed case notes and microbiological findings for 50 patients with SARS, representing more than five separate epidemiologically linked transmission clusters. We defined the clinical presentation and risk factors associated with severe disease and investigated the causal agents by chest radiography and laboratory testing of nasopharyngeal aspirates and sera samples. We compared the laboratory findings with those submitted for microbiological investigation of other diseases from patients whose identity was masked. FINDINGS: Patients' age ranged from 23 to 74 years. Fever, chills, myalgia, and cough were the most frequent complaints. When compared with chest radiographic changes, respiratory symptoms and auscultatory findings were disproportionally mild. Patients who were household contacts of other infected people and had older age, lymphopenia, and liver dysfunction were associated with severe disease. A virus belonging to the family Coronaviridae was isolated from two patients. By use of serological and reverse-transcriptase PCR specific for this virus, 45 of 50 patients with SARS, but no controls, had evidence of infection with this virus. INTERPRETATION: A coronavirus was isolated from patients with SARS that might be the primary agent associated with this disease. Serological and molecular tests specific for the virus permitted a definitive laboratory diagnosis to be made and allowed further investigation to define whether other cofactors play a part in disease progression.

Adult↗
PubMed2002

Respiratory insufficiency in a Chinese adult with mitochondrial myopathy.

Mitochondrial myopathy is an important but uncommon cause of respiratory insufficiency in adults. We report the first case of respiratory insufficiency associated with adult-onset mitochondrial myopathy seen in a Chinese adult in Hong Kong. The patient presented with peripheral oedema and shortness of breath over 2 to 3 days. There was a history of gradual progressive limb weakness over approximately 2 years, hypertrophic cardiomyopathy, intermittent diarrhoea, and weight loss. The diagnosis was made by skeletal muscle biopsy and molecular study, which revealed the A3243G point mutation.

Adult↗
PubMed2001

An investigation of pulsatile release tablets with ethylcellulose and Eudragit L as film coating materials and cross-linked polyvinylpyrrolidone in the core tablets.

To develop new pulsatile release tablets, which can suppress drug release in stomach and release the drug rapidly after a predetermined lag time of about 3 h in intestine, the use of tablets with ethylcellulose/Eudragit L as a coating film and cross-linked polyvinylpyrrolidone in the core tablets was investigated. The release of diltiazem hydrochloride (DIL) as a model drug in the core tablets was investigated in vitro. The lag time (t10) was prolonged with an increase of the coating level, whereas the drug release rate was almost constant, irrespective of the coating level. The water-uptake study and electron microscope photographs suggested the mechanism of pulsatile release of drug. Pulsatile release tablets containing 60 mg DIL with 4.4 h of lag time (t10) in vitro were administrated to eight volunteers. The mean plasma concentration curves showed 4.9 h of lag time (tlag), 8.0 h of time to maximum concentration (tmax) and 3.1 h of time between tmax and tlag (t(psi)) in vivo. Relative bioavailability was 1.05 for pulsatile release tablets compared to conventional tablets.

Adult↗
PubMed1998

Critical care ethics in Hong Kong: cross-cultural conflicts as east meets west.

The practice of critical care medicine has long been a difficult task for most critical care physicians in the densely populated city of Hong Kong, where we face limited resources and a limited number of intensive care beds. Our triage decisions are largely based on the potential of functional reversibility of the patients. Provision of graded care beds may help to relieve some of the demands on the intensive care beds. Decisions to forego futile medical treatment are frequently physician-guided family-based decisions, which is quite contrary to the Western focus on patient autonomy. However, as people acquire knowledge about health care and they become more aware of individual rights, our critical care doctors will be able to narrow the gaps between the different concepts of medical ethics among our professionals as well as in our society. An open and caring attitude from our intensivists will be important in minimizing the cross-cultural conflict on the complex issue of medical futility.

Aged↗
PubMed1998

An investigation of adult outcome of hyperactive children in Shanghai.

Approximately 1-5% of school children have been diagnosed as hyperactive but little is known about their outcome. Children diagnosed as hyperactive in 1979 were followed up for 15 years in order to evaluate their outcome. The manifestations of 197 hyperactive children and 103 normal controls were investigated through follow up with their parents, and the differences were analyzed. Subjects who were diagnosed as MBD (attention deficit hyperactive disorder) in 1979 continued to reveal typical symptoms in 70% of cases and completed less than formal schooling, while only 85% could go through middle school and were less often employed in higher-level professions, and did not exhibit significantly more conduct problems as a whole group compared with normal controls. About 30% of formerly hyperactive children are able to succeed in their academic or occupational performance. However, the adult lives of the others are influenced by such a development deficit.

Achievement↗
PubMed1998

Acute encephalitis complicating rubella.

During an epidemic of rubella in Hong Kong between October 1996 and June 1997, four male patients presented with rubella complicated by encephalitis, the symptoms of which started 1 to 5 days after the appearance of the rash characteristic of rubella. Two patients recovered completely within 1 week and one complained of a slight impairment of short-term memory. Severe cerebral oedema, and herniation across the brainstem and cerebellum developed in the fourth patient, who died 15 days later. The presence of serum immunoglobulin M antibody against rubella virus was demonstrated in all four patients; one patient also had immunoglobulin M antibody against rubella virus in his cerebrospinal fluid. No virus could be isolated during post-mortem examination of the fourth patient.

Journal Article↗
PubMed1994

[2 homoharringtonine resistant leukemic cell lines (K562 HHT and L1210 HHT): establishment, characterization and mechanisms of action].

We developed two leukemic cell lines (K562 HHT and L1210 HHT) stably 16.7 fold and 13.4 fold resistant to HHT respectively with which the culture were treated. Both cell lines were also cross-resistant to DOX, VCR, DNR and Mel. Increased expression of MDR1 gene in the both lines was noted. To further evaluate the implications of MDR1 in HHT resistance. We studied the expression of MDR1 in sensitive and HHT-resistant sublines of K562 by ABC with an monoclonal antibody against P170, JSB-1. K562 HHT cells were positive but sensitive cells were negative. Additionally, the increased drug resistance was associated with increased level of expression of alpha and pi class GST gene, but not with increased level of expression of mu class GST gene.

Animals↗
PubMed1987

Diagnostic value of the Widal test in childhood typhoid fever.

The usefulness of the Widal test in diagnosing childhood typhoid fever in endemic areas was investigated. The test was done on 150 children with other febrile illnesses and 98 bacteriologically proved cases of typhoid fever. Of the 150 children with nontyphoidal fever, only one had an H agglutinin titer of 1:50. Using an H or O agglutinin titer of 1:50 or more as a criterion for diagnosis, a positive Widal test was found in 88% of typhoid fever cases on the first occasion on which the test was done. If the test was repeated at least 94% of the typhoid cases had a significant result. The Widal test is a useful diagnostic test in children in endemic areas, provided interpretation of the test is made against background information relating to agglutinin levels in normal children in the region.

Adolescent↗