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Biomedical subjects

R Leung

Publications and source records attributed to R Leung.

At least 55 records · Page 3Linked to original sources
PubMed1997

Prevalence of latex allergy in hospital staff in Hong Kong.

BACKGROUND: The prevalence of latex allergy in healthcare workers in Asian populations is unknown. METHODS: We studied 1472 employees in a teaching hospital in Hong Kong using written questionnaires and 133 respondents underwent skin prick testing to latex glove eluates and common allergens. RESULTS: Glove-related symptoms were common and 455 (30.9%) reported one or more symptoms, the majority of which could be classified as glove dermatitis (GD). On the other hand, symptoms suggestive of latex allergy such as urticaria, rhinitis, wheeze and asthma, were encountered less frequently and were noted by 3.3%. In particular, one developed asthma and two had wheezing, but there was no report of anaphylaxis. A total of 9.9% reported allergic symptoms from contact with other latex devices, in particular, rubber bands, rubber boots, goggles and swimming. Nine subjects (6.8%) had positive skin test to one or more of the five latex extracts. All were atopic to common allergens. Skin test positivity to latex and banana extracts was positively correlated (P < 0.05). In univariate logistic regression, daily glove use, personal history of allergic disease and history of allergic symptoms to latex-containing devices other than gloves were significant risk factors for both GD and LA. Nurses were more likely to complain of GD and workers with positive skin test to latex were 8.6 times more likely to have symptoms of LA. In multiple logistic regression, the remaining significant associations were between history of daily glove use and GD (OR = 50.11, 95% CI 15.88-158.13), and between positive latex skin test and LA (OR = 8.14, 95% CI 1.27-52.36). CONCLUSION: Glove-related symptoms are common in healthcare workers in Hong Kong. Gloved healthcare workers are at risk of becoming sensitized to latex, and those with positive latex skin tests, long glove exposure time and frequent glove changes are at risk of clinical latex allergy.

Adult↗
PubMed1997

Royal jelly consumption and hypersensitivity in the community.

BACKGROUND: Royal jelly consumption has recently been linked with acute asthma, anaphylaxis and death. A cross-sectional survey was conducted to determine the prevalence of and the relationship between royal jelly consumption and hypersensitivity reactions. METHODS: 1472 hospital employees of a teaching hospital in Hong Kong completed a questionnaire on royal jelly consumption and related allergic symptoms, and 176 questionnaire respondents and 300 consecutive asthma clinic patients were skin tested to royal jelly. RESULTS: Royal jelly consumption was high, with 461 out of 1472 subjects (31.3%) having taken royal jelly in the past. A total of nine subjects reported 14 adverse reactions to royal jelly, including urticaria, eczema, rhinitis and acute asthma. Thirteen out of 176 questionnaire respondents (7.4%) and 23 out of 300 consecutive asthma clinic attendees (7.3%) had positive skin test to pure royal jelly. All but one of the 36 subjects with positive royal jelly skin test were atopic to other common allergens. Positive associations were found between positive royal jelly skin test and atopy (OR = 33.73, 95% CI 4.51 to 252.11), adverse reactions to royal jelly and a history of clinical allergy (OR = 2.88, 95% CI 0.72 to 11.58), but not between royal jelly symptoms and previous royal jelly intake. CONCLUSION: Royal jelly consumption is high in the community of Hong Kong. Atopic individuals are at high risk of sensitization to royal jelly but the precise relationship between royal jelly use, positive royal jelly skin test and clinical manifestations of adverse reactions to royal jelly, remains to be defined.

Adolescent↗
PubMed1997

Comparison of the ISAAC video questionnaire (AVQ3.0) with the ISAAC written questionnaire for estimating asthma associated with bronchial hyperreactivity.

BACKGROUND: A standardized protocol is essential for international comparisons of asthma prevalence and severity. The International Study of Asthma and Allergies in Childhood (ISAAC) used a standardized written questionnaire (WQ) and a video questionnaire (AVQ3.0) to survey the prevalence and severity of asthma in 13-14-year-old schoolchildren in different countries. OBJECTIVE: To compare the effectiveness of WQ and AVQ3.0 in predicting bronchial hyperresponsiveness (BHR), defined as having a provocation dose of inhaled methacholine causing a 20% fall in baseline FEV1 of 7.8 mumol. METHODS: One hundred and eighty-nine Chinese schoolchildren completed a written questionnaire followed by a video questionnaire on asthma symptoms. They then underwent bronchial challenge to methacholine. RESULTS: Fair correlations were seen between the first two corresponding questions (moderate wheezing at rest and exercise wheeze) in the two questionnaires with Kapper indices of 0.44 and 0.43, respectively. The ability to predict BHR, as indicated by the Youden's index, was similar between the corresponding questions of the two questionnaires, except for 'severe wheeze' which had a significantly higher Youden's index in AVQ3.0 (0.44) than the corresponding question in WQ (0.11, P < 0.05). CONCLUSION: The ISAAC International video questionnaire is at least as effective as the ISAAC written questionnaire in predicting BHR. It therefore provides a simple and valid tool for international comparisons of asthma prevalence and severity.

Adolescent↗
PubMed1996

Unusual cause of fever and diarrhea in a patient with AIDS. Penicillium marneffei infection.

Penicillium marneffei is an opportunistic pathogen predominantly found in Southeast Asia. Systemic infection of Penicillium marneffei has protean manifestations including fever, weight loss, anaemia, skin lesions, and lymphadenopathy. We report a rare case of penicillium colitis in an AIDS patient who responded successfully to a course of amphotericin B therapy.

AIDS-Related Opportunistic Infections↗
PubMed1996

Urinary tract infection caused by Mycobacterium terrae complex.

We describe a case of recurrent urinary tract infection caused by Mycobacterium terrae complex in a patient with obstructive nephropathy. The mycobacterium was resistant to most antituberculosis drugs and despite its apparent clearance in the urine, the patient finally died of urinary sepsis caused by multiple bacterial pathogens.

Aged↗
PubMed1996

Gene expression of interleukin-3 and granulocyte macrophage colony-stimulating factor in circulating CD4+ T cells in acute severe asthma.

BACKGROUND: Interleukin (IL)-3 and granulocyte macrophage colony-stimulating factor (GM-CSF) may influence the inflammatory process in asthma through their regulatory role on eosinophil survival, differentiation and effector function. OBJECTIVE: To examine the relationships between IL-3 and GM-CSF messenger (m) ribonucleic acid (RNA) expression in peripheral blood CD4+ cells and serum levels of eosinophil cationic protein (ECP), a marker of eosinophil activation, and disease activity in asthma. METHODS: Venous blood was drawn from patients with acute severe asthma prior to the commencement of systemic steroid therapy (day 1) and 7 days afterwards (day 7), patients with stable disease and normal healthy volunteers. The capacity for expression of IL-3 and GM-CSF in ex vivo stimulated circulating CD4+ cells was assessed semi-quantitatively by reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: We found that the capacity for expression of IL-3 and GM-CSF was significantly higher in acute asthmatics prior to steroid treatment (n = 24) than those in stable disease (n = 38) and healthy subjects (n = 32, P < 0.001 for IL-3 and < 0.05 for GM-CSF), but no difference was observed between the latter two groups. Further assessment made in 15 of the 24 acute asthmatics 7 days after systemic steroid treatment revealed a significant reduction in GM-CSF expression (P < 0.05) but not for IL-3. At the same time, PEF also improved significantly from 30.4 +/- 3.5% of predicted value to 72.9 +/- 7.2% (P < 0.0001) and serum ECP concentration also fell from 19.9 +/- 5.9 micrograms/L to 4.3 +/- 2.0 micrograms/L (n = 10, P < 0.01). CONCLUSION: Our data suggest both IL-3 and GM-CSF may be important in the pathogenesis of acute severe asthma.

Acute Disease↗
PubMed1996

Asthma and anaphylaxis induced by royal jelly.

BACKGROUND: Asthma, together with, in some cases, anaphylaxis, was observed in seven subjects following ingestion of royal jelly, a secretion of honey bees which is used as a health tonic. OBJECTIVE: To determine if reactions were IgE-mediated and to identify allergenic components of royal jelly. METHODS: Skin-prick tests, immunoassays for specific IgE antibodies and protein blotting studies using patients' sera and anti-IgE second antibodies were employed. RESULTS: Immunoassays detected IgE antibodies to royal jelly proteins in sera of subjects who reacted to the substance. A total of 18 different IgE-binding components were detected on blots following electrophoretic separation of royal jelly under dissociating conditions. Examination of 63 sera from subjects allergic to bee venom showed that there is no direct relationship between IgE antibody reactivity to bee venom allergens and to royal jelly proteins although 38% of the sera reacted with a royal jelly solid phase. IgE antibody reactivity to royal jelly proteins was also detected in 52% of 75 subjects with allergies to inhalant and/or food allergens. Antibody binding of blotted royal jelly proteins was most marked in the molecular weight region 25-55 kDa and one component of MW approximately 55 kDa was detected by all of the reactive sera from royal jelly-allergic and control allergic subjects. CONCLUSIONS: Symptoms of asthma and anaphylaxis seen in subjects following ingestion of royal jelly were true IgE-mediated hypersensitivity reactions. The clinical significance of the antibodies found in the sera of control subjects is not known but they may arise in response to common inhalant allergens that show allergenic cross-reactivity with royal jelly.

Adult↗
PubMed1996

Asthma and migration.

The dramatic influx of immigrants from South-East Asian countries into Australia over the past 20 years was associated with an increase is asthma and allergic disease amongst these immigrants. Epidemiological data showed that the prevalence rates of asthma and allergic disease increased with the duration of residence in Australia so that after 10 years in Australia, up to 60% of South-East Asian immigrants developed hayfever while 15% had symptoms of asthma. Many immigrants developed these conditions for the first time after arrival in Australia suggesting that the environment plays a important role in the pathogenesis of asthma and allergy. While sensitization to inhalant allergens such as house dust mite and grass pollen are apparently important in some, other yet undefined local factors are likely to contribute significantly to the overall increase in prevalence. A prospective study designed to follow a group of migrants in areas where asthma and allergic disease are common such as Australia, may reveal the pathogenic role of the environment and provide valuable information that may explain the global distribution and increasing trend of asthma and allergies.

Animals↗
PubMed1996

Effect of inhaled morphine on the development of breathlessness during exercise in patients with chronic lung disease.

BACKGROUND: Inhaled morphine has previously been shown to increase exercise endurance in patients with chronic lung disease. A similar study was performed to determine whether inhaled morphine reduces the sensation of breathlessness in this group of patients. METHODS: A randomised double blind study on the effect of nebulised morphine on both exercise induced breathlessness and maximum achievable power output using isotonic saline as a control was performed in 10 patients with stable chronic lung disease. Each subject performed a progressive exercise test (Jones' stage I) on an electrically braked cycle ergometer. The work load was increased by 10 watts per minute and subjects exercised to exhaustion. At the end of each minute of exercise patients were asked to rate their degree of breathlessness according to a modified Borg scale. All subjects were randomised to receive either inhaled morphine sulphate 1 mg/ml (5 ml) or isotonic saline (5 ml) by wet nebulisation. The effect of morphine and saline on the achieved exercise capacity and the development of breathlessness during exercise was tested on separate days. RESULTS: The mean dose of morphine inhaled was 1.24 mg. There was no difference in maximum power output achieved, minute ventilation at maximum power output, nor the degree of breathlessness at maximum power output between the groups treated with morphine and placebo. The degree of breathlessness was related to the power output achieved during exercise by a power function relationship (mean r: morphine = 0.86, saline = 0.87). However, there was a wide variation in the sensation for any given power output in both groups. There was no difference in the group mean slopes (morphine = 1.15, saline = 1.00) or intercepts (morphine = 0.07, saline = 0.15) in this relationship between the morphine and saline treatment groups. CONCLUSIONS: In patients with severe chronic lung disease inhaled morphine in the doses used in this study does not relieve exercise induced breathlessness nor does it increase maximum power output achieved during progressive exercise.

Administration, Inhalation↗
PubMed1995

Cloning and functional expression of the cDNA encoding rat lanosterol 14-alpha demethylase.

Lanosterol 14 alpha-demethylase (LDM) is a cytochrome P-450 enzyme in the biosynthetic pathway of cholesterol. As such, it represents a target for cholesterol-lowering drugs. Rat LDM (rLDM) has been purified from the livers of rats treated with cholestyramine. The purified protein was used to generate tryptic fragments which were then sequenced. The amino acid (aa) sequences were used to design oligodeoxyribonucleotide primers and a DNA fragment was generated by RT-PCR to probe a phagemid library. A clone encoding rLDM was isolated from the livers of cholestyramine-treated rats. The clone contains an open reading frame encoding a polypeptide of 486 aa and a predicted molecular mass of 55 045 Da. The deduced aa sequence shows a high degree of identity to the yeast LDM sequences, as well as sequences which match typical P-450 sequence motifs. When produced in a baculovirus/insect cell culture system, LDM activity was detected and inhibited by the specific inhibitor azalanstat with an IC50 value of less than 2 nM. The isolation of this full-length coding sequence should facilitate research into understanding the direct and indirect effects of LDM in the regulation of cholesterol biosynthesis and the search for cholesterol-lowering drugs.

Amino Acid Sequence↗
PubMed1995

Mechanisms of DNA demethylation in chicken embryos. Purification and properties of a 5-methylcytosine-DNA glycosylase.

We have previously shown that in developing chicken embryos and differentiating mouse myoblasts, the demethylation of 5-metCpGs occurs through the replacement of 5-methylcytosine by cytosine (Jost, J. P. (1993) Proc. Natl. Acad. Sci. U.S.A. 90, 4685-4688; Jost, J. P. & Jost, Y.C. (1994) J. Biol. Chem. 269, 10040-10043). We have now purified over 30,000-fold a 5-methylcytosine-DNA glycosylase from 12-day-old chicken embryos. The enzyme copurifies with a mismatch-specific thymine-DNA glycosylase and an apyrimidic-endonuclease. The reaction product of the highly purified 5-methylcytosine-DNA glycosylase is 5-methylcytosine. The copurified apyrimidic-endonuclease activity cleaves 3' from the apyrimidic sugar. A 52.5-kDa peptide, isolated as a single band from preparative SDS-polyacrylamide gels, has both the 5-methylcytosine-DNA glycosylase and the mismatch-specific thymine-DNA glycosylase activities. 5-Methylcytosine-DNA glycosylase has an apparent pI of 5.5-7.5 and maximal activity between pH 6.5 and 7.5. The Km for hemimethylated oligonucleotide substrate is 8 x 10(-8) M with a Vmax of 4 x 10(-11) mol/h/micrograms proteins. 5-Methylcytosine-DNA glycosylase binds equally well to methylated and non-methylated DNA. The enzyme reacts six times faster with the hemimethylated DNA than with the same bifilarly methylated DNA sequence, and single-stranded methylated DNA is not a substrate. The action of the enzyme is distributive.

Animals↗
PubMed1995

Conversion of human 15-lipoxygenase to an efficient 12-lipoxygenase: the side-chain geometry of amino acids 417 and 418 determine positional specificity.

Positional specificity determinants of human 15-lipoxygenase were examined by site-directed mutagenesis and by kinetic analysis of the wild-type and variant enzymes. By comparing conserved differences among sequences of 12- and 15-lipoxygenases, a small region responsible for functional differences between 12- and 15-lipoxygenases has been identified. Furthermore, the replacement of only two amino acids in 15-lipoxygenase (at 417 and 418 in the primary sequence) by those found in certain 12-lipoxygenases results in an enzyme that has activity similar to 12-lipoxygenase. An examination of the activity of nine variants of lipoxygenase demonstrated that the amino acid side-chain bulk and geometry of residues 417 and 418 are the key components of the positional specificity determinant of 15-lipoxygenase. Overexpression of a variant (containing valines at positions 417 and 418) that performs predominantly 12-lipoxygenation was achieved in a baculo-virus-insect cell culture system. This variant was purified to > 90% homogeneity and its kinetics were compared with the wild-type 15-lipoxygenase. The variant enzyme has no change in its apparent KM for arachidonic acid and a minor (3-fold) change in its Vmax. For linoleic acid, the variant has no change in its KM and a 10-fold reduction in its Vmax, as expected for an enzyme performing predominantly 12-lipoxygenation. The results are consistent with a model in which two amino acids of 15-lipoxygenase (isoleucine 417 and methionine 418) constitute a structural element which contributes to the regiospecificity of the enzyme. Replacement of these amino acids with those found in certain 12-lipoxygenases results in an enzyme which can bind arachidonic acid in a catalytic register that prefers 12-lipoxygenation.

Arachidonate 12-Lipoxygenase↗
PubMed1994

Asthma, allergy and atopy in southern Chinese school students.

In order to determine the prevalence of asthma, allergy and atopy in southern China and the relative importance of atopy and parental history in predicting asthma and allergic diseases, we carried out a cross-sectional study on 737 secondary school students aged 12-20 (492 boys, 245 girls; mean age = 16.4 years, SD = 1.8 years) in the city of San Bu, Guangdong, China. Standard questionnaires on respiratory and allergic symptoms were distributed for completion by parents with an overall response of 98.6%. Skinprick tests to common aeroallergens were performed on 647 subjects (87.8%) to determine atopic status. The prevalence (and 95% CI) of a history of hay fever, eczema, wheeze or asthma ever and wheeze in past 12 months were 1.6% (0.7-2.5), 10.4% (8.2-12.6), 1.9% (0.9-1.9) and 1.1% (0.3-1.9) respectively. Forty-nine per cent (45.2-52.9) of students had one or more positive skin tests to common aeroallergens. Amongst atopic subjects, 87.3% reacted to house dust mite (Dermatophagoides pteronyssinus) and 73.3% to cockroach. There was a close association between the degree of atopy and the prevalence of a history of wheeze (P < 0.05) but not with hay fever or eczema. After adjusting for age and sex, parental histories of hay fever, eczema and wheeze were strongly associated with the respective symptoms in the subjects (OR = 17.4 (3.2-93.9) for hay fever, 27.4 (12.7-59.0) for eczema, 79.4 (21.9-288.4) for wheeze). It is concluded that respiratory and allergic symptoms were uncommon in Chinese school students despite a high prevalence of atopy, and that parental history is more important in predicting asthma and allergy than atopy.

Adolescent↗