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Biomedical subjects

W Cheung

Publications and source records attributed to W Cheung.

32 records · Page 2Linked to original sources
PubMed1996

Chemotactic Preferences and Strain Variation in the Response of Phytophthora sojae Zoospores to Host Isoflavones.

The zoospores of Phytophthora sojae are chemotactically attracted to the isoflavones genistein and daidzein that are released by soybean roots. In this study we have examined the response of P. sojae zoospores to a wide range of compounds having some structural similarity to genistein and daidzein, including isoflavones, flavones, chalcones, stilbenes, benzoins, benzoates, benzophenones, acetophenones, and coumarins. Of 59 compounds examined, 43 elicited some response. A comparison of the chemotactic responses elicited by the various compounds revealed a primary role for the phenolic 4(prm1)- and 7-hydroxyl groups on the isoflavone structure. A few compounds acted as repellents, notably methylated flavones with a hydrophobic B ring. The chemotactic response to many of the analogs was markedly different among different strains of P. sojae.

Journal Article↗
PubMed1995

Goitre in Australia.

Goitre due to nodular thyroid disease is common. Most patients present with benign disease and are euthyroid at presentation, but careful clinical evaluation (thyroid function tests and fine needle biopsy) is essential to determine appropriate therapy. Thyroid hormone therapy should be reserved for hypothyroid patients and those with Hashimoto's thyroiditis. Iodine supplements are not beneficial. Indications for surgery are a malignant or atypical finding on fine needle biopsy, a recurrent cyst larger than 4 cm in diameter, or a goitre causing obstruction.

Goiter↗
PubMed1995

The effect of age on the presentation of patients with tuberculosis.

OBJECTIVE: To study the differences in presentation of young and elderly patients with tuberculosis (TB). DESIGN: Between January 1991 and December 1992 all patients with TB diagnosed at the Department of Medicine, Prince of Wales Hospital, were recruited into the study. The following data were collected: body weight, coexisting medical problems, presenting symptoms, radiographic appearance, sputum results for acid-fast bacilli and peripheral blood biochemistry. The patients were divided into young ( < 65 years) and elderly ( > or = 65 years) age groups and differences in presentation of the 2 groups were analysed. RESULTS: There were 78 young and 94 elderly patients with TB. The elderly patients had lower body weight, less haemoptysis but more non-specific complaints (25% vs 1%, P = 0.001). The chest radiographs in the elderly patients were less likely to have upper lobe infiltration (9% vs 37%, P = 0.0002) but more commonly had extensive infiltration of both lungs (17% vs 2%, P = 0.014). The only biochemical abnormality that was more common in the elderly was a low serum albumin level (64% vs 45%, P < 0.05). CONCLUSION: Elderly patients with TB are more likely to present with non-specific complaints and atypical radiographic appearance. A high index of suspicion and prompt investigations in elderly patients may allow for earlier diagnosis and treatment of TB.

Adolescent↗
PubMed1995

Adverse drug reactions and outcome of elderly patients on antituberculosis chemotherapy with and without rifampicin.

Antituberculosis (anti-TB) chemotherapy with concomitant administration of rifampicin and isoniazid may cause a higher incidence of hepatotoxicity than isoniazid alone. We carried out a prospective study of the adverse reactions to anti-TB drugs and the clinical outcome in elderly patients on anti-TB chemotherapy, to find out whether the omission of rifampicin from standard anti-TB regime would result in a reduction of adverse reactions and/or mortality during anti-TB treatment. Eighty elderly patients (age > 65 years) with TB were recruited into the study. They were randomised to receive anti-TB chemotherapy consisting of isoniazid, pyrazinamide and ethambutol with or without rifampicin for six months. Adverse reactions and mortality occurring during treatment were noted. A significantly higher number of patients on rifampicin had elevated liver enzymes compared with those not receiving rifampicin. All of these reactions responded favorably to adjustment of anti-TB drugs. There was no significant difference between the two groups in the incidence of symptomatic adverse reactions or mortality during treatment. However, five patients not given rifampicin had unsatisfactory resolution radiographically and required additional therapy. We conclude that the inclusion of rifampicin in the anti-TB regime offers a better therapeutic response but without significantly affecting the incidence of adverse reactions or mortality during treatment in elderly patients with TB.

Aged↗
PubMed1995

Correlation between steady-state plasma concentration of antituberculous drugs and age, inclusion of rifampicin in the treatment regimen, adverse drug reactions and other clinical parameters.

A regional hospital in Hong Kong examined the correlation between plasma concentrations of rifampicin, pyrazinamide, isoniazid and its metabolite hydrazine and age, inclusion of rifampicin in the treatment regimen, adverse drug reactions and other clinical parameters. One hundred eighty subjects with tuberculosis were admitted consecutively to the medical wards of the Prince of Wales Hospital over a one and a half year period. Elderly patients > 65 years were randomized into one of two treatments with and without rifampicin in addition to isoniazid, pyrazinamide and ethambutol; younger patients received all four drugs. Plasma antituberculous drug concentrations were determined using high performance liquid chromatography. Elderly patients taking rifampicin had a higher mean steady-state concentration of isoniazid, together with a higher incidence of adverse effects compared with those not taking rifampicin. No age related differences were observed for the other drugs. For the whole group, higher mean concentrations of hydrazine, rifampicin and pyrazinamide were associated with a higher incidence of adverse effects and the presence of coexisting diseases. It is concluded that in sick elderly patients with coexisting diseases, use of rifampicin in the antituberculous regimen should be accompanied by close monitoring for side effects, and that there may be an indication for use of lower dosages of antituberculous drugs in such patients.

Adult↗
PubMed1994

Ultrasound guided transperineal prostatic aspiration biopsy: experience in Hong Kong.

OBJECTIVE: The purpose of this study is to correlate the result of the ultrasound guided transperineal aspiration biopsy with the clinical findings. MATERIALS AND METHODS: We retrospectively studied 27 patients who had been subjected to ultrasound guided transperineal prostatic aspiration biopsy in our institution during the period 1990 to 1992. The patients were divided into two groups: Group A--those with clinically palpable nodules on digital examination, and Group B--those without palpable nodule but with clinical evidence of prostatic enlargement and/or bladder outlet obstruction. RESULTS: There were 8 biopsy proven cancers, 4 of them were palpable lesions while the other 4 were clinically non-palpable. The overall positive predictive value was 29.6%; this increased to 40% if the lesions were palpable but decreased to 23.5% if the lesions were non-palpable. CONCLUSION: The overall positive predictive value of this technique was found to be consistent with other studies using different methods of biopsies. The positive predictive value was increased if the abnormality was clinically palpable. This technique was also found to be safe and no significant complication was observed in these patients.

Aged↗
PubMed1993

Key features of cereal genome organization as revealed by the use of cytosine methylation-sensitive restriction endonucleases.

Unlike mammalian genomes, cereal (Gramineae) genomes exhibit little suppression of CpG dinucleotides. In cereal genomes, however, most of the numerous potential recognition sites for CpG methylation-sensitive restriction enzymes are methylated. Analysis of cereal genomic libraries and of regions flanking genes indicates that unmethylated NotI sites are useful landmarks for regions containing genes/single-copy sequences. Studies of a rye chromosome arm indicate that its pericentromeric region has a reduced density of unmethylated NotI (and MluI) sites and therefore of genes. Unmethylated MluI and NruI sites are distributed nonrandomly in the genomes of wheat, barley, and rice. Analysis of the genomic blocks defined by these sites in wheat and barley indicates that they are most likely to have arisen by amplification. These observations form the basis of a proposed model for the organization and evolution of the wheat, barley, and rice genomes.

Bacterial Proteins↗
PubMed1991

BIS 1, a major component of the cereal genome and a tool for studying genomic organization.

We report the cloning and characterization of an element (BIS 1) in barley. Related sequences were also found in wheat and rye genomes. BIS 1-related sequences may be some of the more frequent of the complex repeats in the barley genome, and their dispersion throughout the barley genome suggests that they are capable of both mobility and amplification. BIS 1 sequences have been used to study the gross structure of the barley genome. These studies indicate that the genome may be formed from larger genomic structures of tens of kilobases which may be repeated. Surprisingly, these studies also show that these large genomic structures also occur in similar proportions and at similar size distribution in the wheat genome.

Blotting, Southern↗
PubMedDate not supplied

Heterogeneity of amiodarone-induced thyrotoxicosis: evaluation of colour-flow Doppler sonography in predicting therapeutic response.

BACKGROUND: Amiodarone-induced thyrotoxicosis (AIT) presents a therapeutic challenge because of its resistance to standard antithyroid therapy. In iodine-deplete environments, colour-flow Doppler sonography (CFDS) has allowed distinction between two types of AIT: (i) Type I AIT, associated with increased vascularity (CFDS I-III) and response to thionamide antithyroid drug and (ii) type II AIT, with no/little thyroid vascularity (CFDS 0) and prednisolone responsiveness. AIM: To clarify if CFDS patterns correlated with treatment outcomes in a retrospective study of 24 patients with AIT in an iodine-replete environment. METHODS: Medical records of patients who presented to a teaching hospital between January 1998 to December 2000 were reviewed. Results of CFDS, ultrasound measurement of thyroid size and technetium scanning of the thyroid were correlated with treatment responses, especially prednisolone responsiveness. RESULTS: Thirteen of 24 patients showed CFDS 0. Twelve of these 13 were evaluable for prednisolone responsiveness, of whom seven (58%) were prednisolone-responsive. Of 11 patients with CFDS I-III, four (36%) responded to antithyroid medication alone and only one of seven (14%) was prednisolone-responsive. Euthyroidism was achieved twice as rapidly in patients with CFDS 0 than those with CFDS I-III. Because of medical treatment failure, seven patients, from both CFDS groups, required urgent near-total thyroidectomy which was successful and uncomplicated in all cases. CONCLUSIONS: CFDS is useful in the management of AIT because CFDS 0 correlates better with prednisolone response (58%) than CFDS I-III (14%). However, unlike experience in iodine-deficient regions, the results of the present study revealed that treatment responses to thionamide or prednisolone were heterogeneous within uniform CFDS patterns. Thus, prednisolone--responsiveness was not consistently predicted by CFDS 0, but the presence of flow appeared to correlate with non-response to prednisolone.

Adult↗
PubMedDate not supplied

Evaluation of epoetin alpha (rHuEPO) and darbepoetin alpha (DARB) on human burst-colony formation (BFU-E) in culture.

The erythropoietic effect of recombinant human erythropoietin, epoetin alpha (rHuEPO), in promoting the growth of erythroid burst-forming units (BFU-E) was compared with darbepoetin alpha (DARB), a rHuEPO analogue obtained by site-directed mutagenesis. Human bone marrow cells derived from healthy donors were cultured with different concentrations of rHuEPO or DARB for 12 - 21 days and BFU-E were counted using an inverted microscope. The EC50 of rHuEPO was about 10-fold lower than DARB and the size of the colonies was significantly larger in rHuEPO-containing cultures using comparable concentrations. The maximum number of colonies obtained in some rHuEPO-containing cultures was also higher than for DARB. The number of colonies in DARB-containing cultures was increased, in part, by the addition of low concentrations of rHuEPO, but not by DARB, even at high concentrations. We conclude that DARB is not as effective as rHuEPO in supporting the in vitro growth of human BFU-E.

Bone Marrow Cells↗
PubMedDate not supplied

Chronic intussusception in children: report of one case.

Chronic intussusception is defined as intussusception lasting for 14 days or more. Because the clinical manifestation is different from that of acute intussusception, the diagnosis is usually delayed or missed. Ultrasonography is of diagnostic value. We present a 8-year-old boy who had the complaints of marked body weight loss and intermittent abdominal pain for one month. Hydrostatic reduction failed in this case. Laparotomy revealed an ileo-colic intussusception, the leading point of which was a colonic polyp. We would like to emphasize that chronic intussusception frequently appears a nonacute abdominal condition, usually intermittent abdominal pain, and sometimes marked body weight loss and an abdominal mass. Surgical intervention is usually needed in older children because a high incidence of underlying lesions in them.

Child↗