Search PubMed⌕ Search

Biomedical subjects

M Leung

Publications and source records attributed to M Leung.

At least 19 recordsLinked to original sources
PubMed2006

Smoking and tuberculosis among silicotic patients.

The aim of the present study was to investigate the relationship between smoking and tuberculosis (TB) among high-risk silicotic patients in Hong Kong. A cohort of 435 silicotic patients tuberculin tested from 1995-2002 was prospectively followed-up until the end of 2005. Baseline characteristics were analysed with respect to positive tuberculin reaction (> or =10 mm) at baseline and subsequent development of TB. Smoking, alcohol use and body mass index were independent predictors of positive tuberculin reaction at baseline in multiple logistic regression analysis. Total cigarette pack-yrs did not demonstrate any significant effect. The annual incidences of TB were 1,841, 2,294 and 4,181 per 100,000 for never-, ex- and current smokers, respectively. On Cox proportional hazard analysis, current smokers have a significantly higher risk of TB than other silicotic patients (adjusted hazard ratio (95% confidence interval (CI)): 1.96 (1.14-3.35)) after controlling for age, alcohol use, tuberculin status, treatment for latent TB infection and other relevant background/disease factors. A significant dose-response relationship was also observed with the daily number of cigarettes currently smoked. Smoking cessation may reduce 32.4% (95% CI: 6.5-54.0) of the risk. Smoking increases the risk of both tuberculosis infection and subsequent development of the disease among silicotic patients.

Age Factors↗
PubMed2004

A blinded laxative taper for patients with eating disorders.

OBJECTIVE: To evaluate a blinded laxative taper, supervised entirely by pharmacists, in eating disorder patients with laxative dependency. METHODS: All subjects received a blinded laxative taper according to a set protocol, in addition to the usual treatment for their eating disorder. No specific treatment was given for laxative dependency other than the pharmacist's supervisions of the blinded taper. RESULTS: Ten patients were enrolled, of whom seven completed the study. Five of the seven patients (71%) decreased their laxative intake by at least 50%. Of these seven patients, three withdraw completely from laxative use. DISCUSSION: A standardized blinded laxative taper shows promise as a treatment option for laxative dependency in patients with eating disorders. The laxative taper may be less costly and more available than inpatient or psychologically based treatment because it can be given on an outpatient basis under the supervision of a pharmacist.

Adult↗
PubMed2002

Primary cutaneous nocardiosis of the hand: a case report and literature review.

A case of primary Nocardial infection of the hand is presented. This case was notable for lymphocutaneous involvement, and the development of multiple ascending subcutaneous abscesses after healing of the primary lesion. This clinical entity is uncommon, and indicates an atypical infection. Prolonged cultures are required to isolate Nocardia. The infection resolved fully with multiple surgical debridements and prolonged antibiotic therapy.

Anti-Bacterial Agents↗
PubMed2001

Neurologic complications due to catheterization.

In our university cardiac center, the incidence of a cohort of children with acute neurologic complications resulting from cardiac catheterization performed for acyanotic or cyanotic congenital heart disease is 0.38% (14 children of a total of 3,648 catheterization procedures). Neurologic complications consisted of convulsion (n = 10), stroke (n = 6), intracranial hemorrhage (n = 2), extrapyramidal features (n = 1), paraplegia (n = 1), visual impairment (n = 1), hearing impairment (n = 1), and brachial plexus injury (n = 1). The main risk factors included prolonged duration of catheterization procedure and interventional manipulation in addition to cardiac catheterization. The possible mechanisms causing brain injury included cerebral embolism from local clots and hypoxia resulting from complications during the procedure. Other complications included intracranial hemorrhage secondary to anticoagulation and peripheral plexopathy because of prolonged fixed posture during anesthesia. The prognosis for the majority of patients with stroke is good. Neurologic sequelae, such as global developmental delay or epilepsy, occurred in those with hypoxic-ischemic encephalopathy.

Acute Disease↗
PubMed2001

Membrane cofactor protein (MCP; CD46) expression in transgenic mice.

Human membrane cofactor protein (MCP; CD46) is a widely distributed complement regulator. In the mouse, expression of MCP is largely restricted to the testis while a related, widely expressed protein (Crry) appears to perform MCP's (CD46) regulatory activity. We have developed two mouse strains transgenic for human MCP (CD46) utilizing an approximately 400 kb YAC clone carrying the complete gene. A third mouse strain was generated using an overlapping YAC clone isolated from a second library. The expression of human MCP (CD46) in these mouse strains was characterized by immunohistochemistry, FACS, Western blotting and RT-PCR. No differences were detected in the isoform pattern or distribution among the three strains, although the expression level varied according to how many copies of the gene were integrated. The expression profile closely mimicked that observed in humans, including the same pattern of isoform expression as the donor. In addition, tissue-specific isoform expression in the kidney, salivary gland and brain paralleled that observed in man. The transgenic mice expressed low levels of MCP (CD46) on their E, in contrast to humans but in line with most other primates. These mice should be a useful tool to analyse tissue-specific expression, to establish animal models of infections and to characterize the role of MCP (CD46) in reproduction.

Animals↗
PubMed2000

Dissecting sites important for complement regulatory activity in membrane cofactor protein (MCP; CD46).

Membrane cofactor protein (MCP; CD46), a widely distributed regulator of complement activation, is a cofactor for the factor I-mediated degradation of C3b and C4b deposited on host cells. MCP possesses four extracellular, contiguous complement control protein modules (CCPs) important for this inhibitory activity. The goal of the present study was to delineate functional sites within these modules. We employed multiple approaches including mutagenesis, epitope mapping, and comparisons to primate MCP to make the following observations. First, functional sites were located to each of the four CCPs. Second, some residues were important for both C3b and C4b interactions while others were specific for one or the other. Third, while a reduction in ligand binding was invariably accompanied by a parallel reduction in cofactor activity (CA), other mutants lost or had reduced CA but retained ligand binding. Fourth, two C4b-regulatory domains overlapped measles virus interactive regions, indicating that the hemagglutinin docks to a site important for complement inhibition. Fifth, several MCP regulatory areas corresponded to functionally critical, homologous positions in other CCP-bearing C3b/C4b-binding proteins. Based on these data and the recently derived crystal structure of repeats one and two, computer modeling was employed to predict MCP structure and examine active sites.

Amino Acid Sequence↗
PubMed2000

Estimating the components of the gap effect.

The gap effect refers to the finding that saccadic latencies are typically reduced when a fixation point is removed prior to the appearance of a peripheral target. This reduction in saccadic reaction time (SacRT) is thought to be due to a general warning effect and an oculomotor specific fixation offset that occur when the fixation point is removed. In order to estimate the contribution of each of these effects to the overall gap effect, this paper introduces a new manipulation, the partial-gap trial, where the fixation point undergoes a change in size prior to the presentation of the target. The partial-gap trial is presumed to provide the visual warning effect of the fixation offset (i.e. similar to that in a gap trial) but does not provide the fixation offset effect (FOE). When the fixation point was abruptly reduced in size before the presentation of the target, the estimated decrease in SacRT due to the visual warning effect was 5-7% and did not differ in the presence or absence of an auditory warning signal. It was found that auditory warning effect and the FOE interacted in reducing SacRTs. Additionally, when the fixation point was abruptly increased in size before the presentation of the target, SacRTs were slower than when the fixation point did not change in size and remained present for the entire trial (i.e. an overlap trial). We conclude that this new partial-gap paradigm is a useful method for researchers wishing to separately examine FOE and visual warning effects.

Adult↗
PubMed2000

Nerve growth factor potentiated the sodium butyrate- and PMA-induced megakaryocytic differentiation of K562 leukemia cells.

We have recently reported that retinoic acid (RA) induced the expression of trkA, the high affinity receptor for nerve growth factor (NGF), in human chronic myelogenous leukemia K562 cells. In this paper, we examined the ability of several other differentiation inducers to regulate the expression of trkA and NGF in K562 cells. We found that the expression of trkA was dramatically induced by the two megakaryocyte lineage inducers sodium butyrate (NaBut) and phorbol 12-myristate 13-acetate (PMA), but not by the two erythrocyte lineage inducers hemin or 1-beta-D-arabinofuranosyl cytosine (Ara-C). Furthermore, activation of the up-regulated trkA receptor by exogenous NGF potentiated the megakaryocytic differentiation of K562 cells induced by NaBut and PMA. Our results demonstrated that trkA is one of the essential genes that are up-regulated and involved in the megakaryocytic differentiation of K562 leukemia cells triggered by these differentiation inducers. Our findings suggest that NGF, in addition to its pivotal roles in the nervous system, may also play important roles in hematopoietic differentiation.

Butyric Acid↗
PubMed2000

Maximising the clinical use of exercise gaseous exchange testing in children with repaired cyanotic congenital heart defects: the development of an appropriate test strategy.

Implicit in deciding upon an exercise test strategy to elucidate cardiopulmonary function in children with congenital heart disease are appropriate application of gas exchange techniques and the significance of the data collected to the specific congenital heart disorder. Post-operative cardiopulmonary responses to exercise in cyanotic disorders are complex and, despite a large body of extant literature in paediatric patients, there has been much difficulty in achieving quality and consistency of data. Maximal oxygen uptake is widely recognised as the best single indicator of cardiopulmonary function and has therefore been the focus of most clinical exercise tests in children. Many children with various heart anomalies are able to exercise to maximum without adverse symptoms, and it is essential that test termination is based on the same criteria for these children. Choosing appropriate, valid indicators of maximum in children with congenital heart disease is beset by difficulties. Such maximal intensity exercise testing procedures have been challenged on the grounds that they do not give a good indication of cardiopulmonary function that is relevant to real life situations. Furthermore, they are prone to much interindividual variability and error in the definition of maximal exertion. Alternative strategies have been proposed which focus upon dynamic submaximal and kinetic cardiopulmonary responses, which are thought to be less dependent on maximal voluntary effort and more suited to the daily activity patterns of children. These methods are also not without problems. Variability in anaerobic threshold measurements and controversy regarding its physiological meaning have been debated. It is recommended that an appropriate cardiopulmonary exercise gas exchange test strategy, which provides clinically useful information for children with cyanotic congenital heart disease, should include both maximal and submaximal data. The inclusion of oxygen uptake kinetics and ventilatory data are encouraged, since they may allow the distinction between a pulmonary, cardiovascular or inactivity related exercise limitation.

Age Factors↗
PubMed1999

Ring avulsion injuries.

BACKGROUND: Ring avulsion injuries can vary in severity from mere breach of the skin through to complete amputation or degloving. Management of the more severe injuries remains controversial in deciding whether to salvage or amputate. METHOD: Six cases managed between 1991 and 1997 are presented. RESULTS: Results were comparable to the larger series published. CONCLUSION: Referral to a microsurgical unit and attempted repair where possible are recommended.

Female↗
PubMed1999

Free toe pulp transfer for digital reconstruction after high-pressure injection injury.

We report two cases of high-pressure injection injuries to the fingertip in which free toe pulp flaps were used to resurface the palmar surface of the finger following extensive wound debridement. There was good return of sensibility and, because of the high durability of the donor skin, both patients regained good functional use of the injured digits and returned to heavy manual work. There was minimal associated morbidity of the donor sites. The free toe pulp flap represents an excellent alternative for resurfacing the digit with a large residual skin defect after high-pressure injection injury.

Accidents, Occupational↗
PubMed1999

Survey of vitamin and mineral supplementation after gastric bypass and biliopancreatic diversion for morbid obesity.

BACKGROUND: The authors investigated whether practice patterns of bariatric surgeons correlate with published data regarding metabolic deficiencies after Roux-en-Y gastric bypass (RYGB) and biliopancreatic diversion (BPD). METHODS: 109 surgeons completed a questionnaire to determine use of supplements and frequency of lab tests. RESULTS: Regarding supplements routinely prescribed after RYGB, 96% of surgeons gave multivitamins, 63% gave iron, and 49% gave vitamin B12. After BPD, 96% of surgeons gave multivitamins, 67% gave iron, 42% gave vitamin B12, 97% gave calcium, 63% gave fat-soluble vitamins, and 21% gave protein supplements. Regarding laboratory tests obtained routinely after RYGB, 95% of surgeons do complete blood counts, 56% do iron determinations, 66% do vitamin B12 determinations, 58% do folate determinations, 76% do electrolyte determinations, and 8% test for proteins. After BPD, 96% of surgeons do complete blood counts, 80% do iron determinations, 67% do vitamin B12 determinations, 71% do folate determinations, 88% do electrolyte determinations, 84% do protein determinations, and 46% test for fat-soluble vitamins. Regarding frequency of blood tests, after RYGB, 22% of surgeons obtain them after 3 months, 33% after 6 months, and 41% after 12 months; 4% do not routinely obtain postoperative laboratory tests. After BPD, 46% of surgeons obtain them after 3 months, 33% after 6 months, and 16% after 12 months; one does not obtain laboratory tests. Surgeons estimated these deficiencies after RYGB: 16% iron, 12% vitamin B12, 14% anemia, 5% protein, and 3% calcium. They estimated these deficiencies after BPD: 26% iron, 11% vitamin B12, 21% anemia, 18% protein, 16% calcium, and 6% fat-soluble vitamins. The estimated incidence of deficiencies after RYGB was considerably lower than the published incidence. Unnecessary tests were commonly performed (electrolytes after RYGB). CONCLUSION: Despite wide variations in the performance of laboratory tests and the use of supplements, the practice patterns of most surgeons protect patients from developing severe metabolic deficiencies after RYGB and BPD.

Biliopancreatic Diversion↗
PubMed1997

The combined differentiating effect of retinoic acid and vincristine on acute promyelocytic leukemia.

We have previously shown that HL-60 cells exposed to all-trans retinoic acid (ATRA) after treatment with a non-cytotoxic concentration of vincristine (VCR) result in granulocytic maturation and differentiation, suggesting that VCR might exhibit a synergistic action with ATRA in the treatment of acute promyelocytic leukemia. In this report, leukemic cells obtained from a patient with acute promyelocytic leukemia were exposed to 20 nM VCR for 1 h followed by 1 microM ATRA for 6 days. An increase in the expression of mature myelocyte antigens, CD11b and CD15, was observed as determined by flow cytometric analysis. Treatment of VCR or ATRA alone, however, did not have any effect on the expression of these mature myelocyte antigens of the leukemic cells. These results suggest that combined VCR and ATRA may be more efficient in the differentiation therapy of acute promyelocytic leukemia, particularly in those cases showing a slow response to ATRA therapy.

Antigens, CD↗