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Biomedical subjects

C K Lai

Publications and source records attributed to C K Lai.

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

Prevalence of asthma and allergy in Hong Kong schoolchildren: an ISAAC study.

Asthma and allergic disease in children is increasing in many Western countries but such trend has not been well-defined in Chinese populations. This paper aims to determine the prevalence of asthma and allergic disease in Hong Kong schoolchildren and compare it with previous data to identify a changing trend. We studied 4,665 schoolchildren aged 13-14 yrs using the International Study of Asthma and Allergy in Childhood (ISAAC) protocol to determine prevalence rates for asthma, wheeze, respiratory symptoms, rhinitis and eczema in 1994-1995. Additional questions on education levels of the parents and smoking status were also asked. Concordance between responses to the written and video questionnaires was good (76% for wheeze ever, 80% for current wheeze). Prevalence rates for asthma ever, wheeze ever, and current wheeze were 11, 20 and 12%, respectively, and were greater in boys (p < 0.05). Rhinitis affected slightly over half of the subjects (52%), and eczema was reported by a sixth (15%), whilst current rhinitis and current eczema were present in 44% and 3.6% of children, respectively. In multiple logistic regression: odds ratio male sex (OR) 1.47; (95% confidence interval (95% CI) 1.15-1.86); current rhinitis (OR 3.00; 95% CI 2.36-3.81); current eczema (OR 2.34; 95% CI 1.40-3.93); and active smoking (OR 2.00; 95% CI 1.38-2.89) were associated with current wheeze; whilst severe wheezing attack was associated with: current rhinitis (OR 2.72; 95% CI 1.47-5.02); current eczema (OR 6.13; 95% CI 2.82-13.33); and active smoking (OR 4.62; 95% CI 2.43-8.76). Age, parental education and passive smoking were not important factors. When compared to previous epidemiological data obtained in 1992, the prevalence rates for asthma ever and wheeze ever had increased by 71 and 255%, respectively, in Hong Kong schoolchildren. The severity of asthma and respiratory symptoms showed a similar increasing trend. Further studies should aim to identify the role of the environment in the pathogenesis of asthma.

Adolescent↗
PubMed1997

Cytokine gene expression profile of circulating CD4+ T cells in active pulmonary tuberculosis.

T lymphocytes, particularly CD4+ cells, are thought to play an important role in the immune defense against Mycobacterium tuberculosis through the release of their wide array of cytokines. In vitro studies suggest that Mycobacterium-specific T-cell clones are of the TH1 subtype. Using the technique of reverse transcription-polymerase chain reaction, we have investigated the capacity for cytokine gene expression profile in ex vivo circulating CD4+ T cells from 20 patients with active pulmonary tuberculosis compared with that of 30 normal healthy tuberculin-positive volunteers. Venous blood samples were collected from the former prior to the initiation of chemotherapy. A significant increase in interleukin (IL-2) expression (p < 0.001) and a significant decrease in IL-5 expression (p < 0.0001) were observed in patients with tuberculosis but no differences were seen in the expression of IL-4 and interferon gamma between the two study groups. Our data support a TH1-like immune response in active tuberculosis.

Adolescent↗
PubMed1997

Effect of anti-DNA autoantibodies on the gene expression of interleukin 8, transforming growth factor-beta, and nitric oxide synthase in cultured endothelial cells.

Our study aims to determine whether anti-dsDNA exerts any effect on the gene expression of IL-8 or TGF-beta in cultured HUVEC. Both cytokines have angiogenic effect on endothelial cells. IgG was purified from 19 patients with SLE and from 19 healthy controls. Anti-dsDNA-depleted polyclonal IgG was also prepared from serum IgG of lupus patients by affinity chromatography with DNA cellulose column. Compared with either control IgG or anti-dsDNA-dep-IgG, HUVEC incubated with anti-dsDNA-containing-IgG expressed higher levels of IL-8 mRNA (p = 0.0001) and TGF-beta 1 mRNA (p = 0.0014). We demonstrated a significant increase in the percentage of cells with fragmented DNA in HUVEC incubated with anti-dsDNA-containing-IgG compared with those incubated with anti-dsDNA-dep-IgG, supporting the notion that anti-dsDNA may exert a direct apoptotic effect on cultured endothelial cells. Our study provides in vitro evidence that anti-dsDNA could play an important pathogenetic role in inducing inflammatory injury of vascular endothelium in SLE.

Adult↗
PubMed1997

Uniform solid-phase extraction procedure for toxicological drug screening in serum and urine by HPLC with photodiode-array detection.

In this HPLC-diode-array detection method for toxicological drug screening, a mixed-mode solid-phase extraction procedure is optimized for isolation of a broad range of drugs from serum and urine. Basic, neutral, and weakly acidic drugs are uniformly recovered. The extract from the solid-phase cartridge is readily injected to a reversed-phase HPLC column for separation by gradient elution. Unknown drugs and metabolites in urine and serum samples from acute drug poisoning cases are rapidly identified by matching their retention times and ultraviolet spectra with hundreds of reference compounds in the library. Urine metabolites of common toxicants from various medications and drugs of abuse are recorded, with their changes of retention times and ultraviolet spectra as related to their metabolic transformations. Glucuronide conjugates of common benzodiazepines, tricyclic antidepressants, and beta-blockers are examined directly without chemical or enzymatic hydrolysis. The system is reliable for diverse clinical investigations of drug overdoses, drug-induced psychoses, and substance abuse.

Blood Chemical Analysis↗
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

Neutrophil attractant protein-1 interleukin 8 and its autoantibodies in IgA nephropathy.

Human neutrophil attractant protein-1/interleukin 8 (IL-8) has been shown to activate neutrophils to degranulate in vitro and to be a potent chemotactic agonist for neutrophils and lymphocytes in vitro and in vivo. There is accumulating evidence that neutrophils are involved in inflammatory injury in IgA nephropathy (IgAN). We studied the serum levels of IL-8 and its autoantibodies of the IgA or IgG class in 36 patients with IgAN in comparison with 31 healthy controls and 26 patients with other primary glomerulonephritides (CGN). Interleukin 8 was more frequently detected in sera of patients with IgAN and their serum levels were significantly higher than those of healthy controls. The free IL-8 autoantibodies of the IgA, but not IgG class, were more frequently detected in patients with IgAN and their serum levels were significantly elevated compared with both groups of controls. The complexed IL-8 autoantibodies of either class were not different among the three groups of subjects. Again the ratio of free to complexed IL-8 autoantibodies of the IgA class was raised in patients with IgAN. Histologic examination revealed increased polymorphs and monocyte/macrophage infiltration in IgAN compared with other glomerulonephritides. When the serum levels of IL-8 and IL-8 autoantibodies were compared between IgAN patients with milder pathology and those with more severe pathology, the latter group had significantly higher serum levels of free and complexed IL-8 autoantibodies of the IgA class. These observations suggest a possible role for IL-8 and its autoantibodies of the IgA class in the inflammatory process of IgAN. These autoantibodies may provide a clinically useful marker for the diagnosis of disease severity.

Adult↗
PubMed1996

Upregulation of adhesion molecule expression on endothelial cells by anti-DNA autoantibodies in systemic lupus erythematosus.

The mechanism of vasculopathy in systemic lupus erythematosus (SLE) remains unclear and the evidence for a direct pathogenic role of anti-double-stranded DNA antibodies (anti-dsDNA) is not strong. Our study aims to determine whether anti-dsDNA exerts any effect on the expression of adhesion molecules on endothelial cells. IgG was purified from 17 patients with SLE (median anti-dsDNA titer, 404 IU/ml) and from 9 healthy controls (median titer 16 IU/ml). Anti-dsDNA-depleted polyclonal IgG (anti-dsDNA-dep-IgG) (median anti-dsDNA titer 17 IU/ml) was prepared from sera of these patients with SLE by affinity chromatography with DNA cellulose column. Expression of intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and E-selectin on human umbilical vein endothelial cells (HUVEC) cultured with either control IgG or anti-dsDNA were compared by flow cytometry. The levels of adhesion molecules in the supernatant of cultured HUVEC were assessed by sandwich ELISA. Compared with either control IgG or anti-dsDNA-dep-IgG, HUVEC incubated with anti-dsDNA expressed a significantly higher mean fluorescence intensity of ICAM-1 and in VCAM-1 and a higher supernatant concentration of ICAM-1 and VCAM-1 but not E-selectin. At the same time, ICAM-1 mRNA was also raised with increased neutrophil adherence in HUVEC incubated with anti-dsDNA. Pretreatment of HUVEC with native DNA or histone before incubation with anti-dsDNA did not increase the expression of adhesion molecules. Our study provides in vitro evidence that anti-dsDNA could play an important pathogenic role in inducing inflammatory injury of vascular endothelium in SLE.

Adult↗
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

Interleukin-5 messenger RNA expression in peripheral blood CD4+ cells in asthma.

BACKGROUND: IL-5 has been implicated in the pathogenesis of asthma through its regulatory role on eosinophil survival, proliferation, and effector function. OBJECTIVE: The study was designed to investigate the relationships between IL-5 messenger RNA expression in circulating CD4+ cells and serum concentrations of eosinophil cationic protein (ECP), a marker of eosinophil activation, and disease activity in asthma. METHODS: IL-5 gene expression was assessed semiquantitatively in ex vivo stimulated CD4+ cells by reverse transcription-polymerase chain reaction and serum ECP concentration measured from venous blood samples collected from patients with acute severe asthma before the commencement of systemic steroid therapy (day 1) and on day 7 and from patients with stable asthma and healthy volunteers. RESULTS: IL-5 gene expression was significantly higher in patients with acute asthma before steroid treatment than in those with stable disease and healthy subjects (p < 0.0001). Similar results were obtained with serum ECP levels: levels in patients with acute asthma were highest (20.30 +/- 5.31 micrograms/L), followed by levels in patients with stable asthma (2.76 +/- 0.65 micrograms/L) and levels in normal control subjects (1.37 +/- 0.06 micrograms/L; p < 0.01 for all comparisons). Significant falls in both IL-5 expression and serum ECP level were seen on day 7 (p < 0.001) and coincided with a significant improvement in peak expiratory flow (p < 0.0001). Significant correlations were observed between IL-5 expression and ECP level (rho = 0.39, p < 0.01), IL-5 expression and peak expiratory flow (rho = -0.55, p < 0.0002), and peak expiratory flow and ECP level (rho = -0.32, p < 0.04). CONCLUSION: Our data therefore support an important regulatory role of IL-5 on eosinophil function in human asthma in vivo.

Acute Disease↗
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

Effect of renal transplantation on pulmonary function in patients with end-stage renal failure.

Ten patients with end-stage renal failure on maintenance dialysis underwent serial lung function tests before and at monthly intervals after renal transplantation. Mean values of forced expiratory volume within 1 s, forced vital capacity, and total lung capacity were within the normal range before and up to 6, months after transplantation. The mean value of residual volume (RV) was above the normal range during all periods measured (157.8 +/- 21.5% predicted before transplantation and 121.2 +/- 17.0% predicted at 6 months after transplantation). No statistically significant changes in lung volumes were detected over a course of 6 months, but there was a trend for a reduction in RV after transplantation. The single-breath diffusion capacity for carbon monoxide (DLCO) was in the high-normal range before transplantation (115.7 +/- 9.5% predicted). It remained high at 1 month after transplantation (124.5 +/- 12.2% predicted), but it gradually came down to the normal range from the 2nd month onwards. At 6 months after transplantation the mean DLCO was 83.8 +/- 7.3% of predicted which was significantly (p < 0.0001) lower than the value before transplantation. We conclude that raised DLCO and RV values occurred in patients with end-stage renal failure on maintenance dialysis which were most likely the result of pulmonary vascular congestion, and these abnormalities tend to improve after renal transplantation.

Adult↗
PubMed1996

Anti-DNA autoantibodies stimulate the release of interleukin-1 and interleukin-6 from endothelial cells.

The pathogenetic mechanism of vasculitis in systemic lupus erythematosus (SLE) remains a subject of debate. Evidence for a direct pathogenetic role of anti-double-stranded DNA antibodies (anti-dsDNA) is not strong. Supernatant concentrations of interleukin-1 beta and interleukin-6, and mRNAs encoding for interleukin-1 alpha and interleukin-1 receptor-1 were determined in cultured human umbilical vein endothelial cells (HUVEC), incubated with control IgG (n = 18), anti-dsDNA (n = 18), or IgG from the same lupus patient depleted of anti-dsDNA by affinity chromatography (anti-dsDNA-dep-IgG). Compared with control IgG, there was a significant increase of supernatant interleukin-1 beta and interleukin-1 alpha mRNA in endothelial cells incubated with anti-dsDNA. The supernatant interleukin-1 beta and interleukin-6, and mRNAs encoding for interleukin-1 alpha and interleukin-1 receptor-1, were significantly elevated in endothelial cells incubated with anti-dsDNA, compared with those incubated with anti-dsDNA-dep-IgG. Pretreating HUVEC with native DNA before incubating with anti-dsDNA did not result in an additive effect. These in vitro studies suggest that anti-dsDNA plays an important pathogenetic role in inducing inflammatory injury of vascular endothelium in SLE.

Adult↗
PubMed1995

Heparin binding to platelet factor-4. An NMR and site-directed mutagenesis study: arginine residues are crucial for binding.

Native platelet factor-4 (PF4) is an asymmetrically associated, homo-tetrameric protein (70 residues/subunit) known for binding polysulphated glycosaminoglycans like heparin. PF4 N-terminal chimeric mutant M2 (PF4-M2), on the other hand, forms symmetric tetramers [Mayo, Roongta, Ilyina, Milius, Barker, Quinlan, La Rosa and Daly (1995) Biochemistry 34, 11399-11409] making NMR studies with this 32 kDa protein tractable. PF4-M2, moreover, binds heparin with a similar affinity to that of native PF4. NMR data presented here indicate that heparin (9000 Da cut-off) binding to PF4-M2, while not perturbing the overall structure of the protein, does perturb specific side-chain proton resonances which map to spatially related residues within a ring of positively charged side chains on the surface of tetrameric PF4-M2. Contrary to PF4-heparin binding models which centre around C-terminal alpha-helix lysines, this study indicates that a loop containing Arg-20, Arg-22, His-23 and Thr-25, as well as Lys-46 and Arg-49, are even more affected by heparin binding. Site-directed mutagenesis and heparin binding data support these NMR findings by indicating that arginines more than C-terminal lysines, are crucial to the heparin binding process.

Amino Acid Sequence↗