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Ooi GC, Khong PL, Chan GCF, Chan KN, Chan KL, Lam W, Ng I, Ha SY. Magnetic resonance screening of iron status in transfusion-dependent β-thalassaemia patients. Br J Haematol 2004; 124:385-90. [PMID: 14717788 DOI: 10.1046/j.1365-2141.2003.04772.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The clinical utility of dual sequence (T1- and T2-weighted) magnetic resonance (MR) imaging in estimating liver iron concentration (LIC) in 32 transfusion-dependent beta-thalassaemia major (24 females; age 18.5+/-5.9 years) patients on desferrioxamine was evaluated. Signal intensity ratios (SIR) between liver, spleen and pancreas to psoas muscle were determined on both sequences. Relationships between clinical and MR parameters, and accuracy of SIR thresholds in determining adequacy of chelation from LIC were analysed. Liver T1- and T2-SIR were related to LIC (P < 0.001). T1-SIR < 0.60 predicted severe iron overload (LIC > 15 mg/g) with sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of 100%, 87%, 33% and 100% respectively. T2-SIR < 0.1 yielded 100% sensitivity, 93% specificity, 50% PPV and 100% NPV. T1-SIR > or = 1.1 predicted LIC < 7 mg/g with 69% sensitivity, 88% specificity, 85% PPV and 74% NPV. T2-SIR > or = 0.20 yielded 56.5% sensitivity, 94% specificity, 90% PPV and 71% NPV. LIC correlated with liver T1-SIR, liver T2-SIR and serum ferritin (r = -0.76, -0.65, 0.47, respectively; P < 0.01). Serum ferritin was inversely related to liver T1-SIR, liver T2-SIR and spleen T2-SIR (r = -0.35, -0.43, -0.40, respectively; P < 0.05). Mean total transfusion burden was not related to any MR parameter. Although neither MR sequence was a highly accurate predictor of LIC, SIR thresholds are useful to determine presence of iron overload and adequacy of chelation treatment.
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Affiliation(s)
- G C Ooi
- Department of Diagnostic Radiology, The University of Hong Kong, Room 405/Block K, Queen Mary Hospital, Hong Kong SAR, China.
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Ho JC, Chan KN, Hu WH, Lam WK, Zheng L, Tipoe GL, Sun J, Leung R, Tsang KW. The effect of aging on nasal mucociliary clearance, beat frequency, and ultrastructure of respiratory cilia. Am J Respir Crit Care Med 2001; 163:983-8. [PMID: 11282777 DOI: 10.1164/ajrccm.163.4.9909121] [Citation(s) in RCA: 173] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The increased susceptibility of the elderly to lower respiratory tract infection cannot be fully explained. Although mucociliary clearance, which is affected by ciliary beating and ultrastructure, plays a crucial role in the defense of the airways against inhaled microbes, little is known of the effects of aging on these parameters. We studied the nasal mucociliary clearance (NMCC) time, ciliary beat frequency, and ultrastructure of respiratory cilia in a cohort of healthy volunteers (age range 11 to 90 yr). Ciliary beat frequency of ciliated nasal epithelial cells was obtained via an established photometric method, and NMCC time was measured with the saccharine test. There was a correlation of ciliary beat frequency (r = -0.48, p = 0.0001) and NMCC time r = 0.64, p < 0.001) with increasing age. Transmission electron microscopy revealed an increase in the percent of subjects exhibiting microtubular disarrangement and single central microtubules with aging (p = 0.002 and p = 0.005, respectively). Subjects older than 40 yr of age had significantly slower ciliary beat frequency, higher percent of ciliary cross-sections displaying single tubules, and longer NMCC time than their younger counterparts (p < 0.05). These findings may help explain the frequent occurrence of respiratory infection in the elderly.
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Affiliation(s)
- J C Ho
- University Departments of Medicine, Pediatrics, and Anatomy, The University of Hong Kong, Queen Mary Hospital, Hong Kong, China
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Ooi GC, Kwong DL, Chan KN, Ngan H, Lock DT, Lam WK, Chan FL, Au G, Tsang KW. Serial HRCT lung changes after 3-field radiation treatment of breast cancer. Clin Radiol 2000; 55:817-24. [PMID: 11069735 DOI: 10.1053/crad.2000.0542] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
AIMS To document serial high resolution computed tomography (HRCT) features of lung injury after 3-field radiotherapy for breast cancer. MATERIALS AND METHODS Thirty women who received opposing tangential chest wall and supraclavicular field (SCF) irradiation after breast surgery were recruited. Thoracic HRCT was performed before and at 1, 3, 6 and 12 months after radiotherapy (RT). Lung injury at 3 months was quantified by applying a scoring system to each HRCT section. Findings were correlated with spirometric lung function tests. RESULTS There was HRCT evidence of lung injury in 27 (90%) women at 1 month and in all 30 patients at 3 months. Spirometric lung function declined post-RT (P < 0.05), correlating with an increased SCF acute lung injury score at 3 months [r = -0.54 and -0.46, P = 0.01 and 0.03 for forced expiratory volume in 1st (FEV(1)) and forced vital capacity (FVC), respectively]. Lung injury on HRCT progressed from ground glass opacification at 1 month to nodular consolidation (3 months), increasing linear densities (6 months), and finally to residual subpleural linear and dense opacities (12 months). CONCLUSION There is a high incidence of lung injury associated with 3-field radiotherapy for breast cancer, with concurrent SCF irradiation increasing the risk of lung damage and functional impairment. A characteristic sequence of HRCT changes is seen in most patients receiving this type of radiotherapy.Ooi, G. C. (2000). Clinical Radiology55, 817-824.
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Affiliation(s)
- G C Ooi
- Department of Diagnostic Radiology, The University of Hong Kong, Hong Kong SAR, China.
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Abstract
OBJECTIVES The aim was to study the yield of malignant or suspicious cells from bronchoalveolar lavage (BAL), endobronchial biopsy (BX) and endobronchial brushing (BR) specimens obtained at bronchoscopy. METHODOLOGY We prospectively followed up all patients who had undergone bronchoscopy and studied those with subsequent diagnosis of bronchial carcinoma at a tertiary referral centre. Bronchoalveolar lavage, BX and BR were performed, sequentially whenever possible, by one pulmonologist. The parameters assessed were age, gender, macroscopic bronchoscopic findings, TNM staging, radiological findings, histological typing, and diagnostic yield from BAL, BX, and BR. RESULTS One hundred patients (31 females, 69 males; mean age +/- SD, 61.8+/-12.7 years; range 32-81 years) were studied between 1995 and 1997. Of these, BAL, BX and BR were performed on 100, 64 and 37 cases which yielded diagnostic specimens for bronchial carcinoma in 69, 78.1, and 62.2% of cases, respectively (P > 0.05). Diagnostic specimens were therefore obtained in 69,50, and 23% of the entire patient cohort from BAL, BX, and BR, respectively (P < 0.001). The diagnostic yield of BAL was independent of patient age, gender, site of lesion, TNM staging, histological typing and macroscopic bronchoscopic findings. Addition of BX, BR and postbronchoscopic sputum sampling to BAL only increased the yield of diagnostic specimens for bronchial carcinoma by 7, 0, and 4%, respectively. CONCLUSION Bronchoalveolar lavage is a highly effective sampling method to obtain cytological evidence for bronchial carcinoma. The diagnostic yield for BAL is independent of tumour or other clinical characteristics. Further studies should be performed to confirm these important and clinically relevant findings.
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Affiliation(s)
- B Lam
- University Department of Medicine, Queen Mary Hospital, The University of Hong Kong, SAR, China
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Ip MS, Karlberg EM, Chan KN, Karlberg JP, Luk KD, Leong JC. Lung function reference values in Chinese children and adolescents in Hong Kong. II. Prediction equations for plethysmographic lung volumes. Am J Respir Crit Care Med 2000; 162:430-5. [PMID: 10934065 DOI: 10.1164/ajrccm.162.2.9905058] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
As part of a comprehensive evaluation of lung function in Hong Kong Chinese children and adolescents, over a thousand healthy subjects aged 7-19 yr from seven schools were recruited for lung function testing that included spirometry and, in many cases, lung subdivision measurements. Lung function tests were performed using SensorMedics Automated Body Plethysmograph according to published standards. Of these, 551 subjects (219 males), aged 8-19 yr, had satisfactory lung subdivision indices recorded. Analysis for the values of lung subdivisions including total lung capacity (TLC), residual volume (RV), and functional residual capacity (FRC) demonstrated that standing height and sitting height were the best predictors of lung volumes. After allowing for standing height or sitting height in the regression models for lung volumes, age at examination was the second best parameter, although its inclusion into the equations contributed to less than 1% of explained variance for boys and 3% for girls. These are the first reported data in international literature on reference values for lung subdivisions in Chinese children and adolescents.
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Affiliation(s)
- M S Ip
- Departments of Medicine, Orthopedic Surgery, and Pediatrics, The University of Hong Kong, Hong Kong SAR, China.
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Abstract
Asthma is a very common respiratory disease which is characterized by the presence of cytokine-mediated airway inflammation leading to smooth muscle contraction, oedema and progressive airway damage in some cases. In light of our recent finding of an increased sero-prevalence of Helicobacter pylori in bronchiectasis, we have determined serum levels of H. pylori-specific IgG in asthmatic and control subjects. Altogether 90 consecutive asthmatic [mean age +/- SD 42.6+/-16 years and 52 female (F)] and 97 healthy control subjects (mean age +/- SD 43.2+/-13.3 years and 51 female (F); P = 0.78 and 0.39 respectively) were recruited prospectively. H. pylori sero-prevalence was not significantly different between asthmatic and control subjects (P>0.05). Serum H. pylori IgG levels did not correlate with FEV1 % predicted, FVC % predicted or duration of asthma (P>0.05). Similar to the results of previously published sero-epidemiological studies, there was a weak correlation between serum H. pylori IgG with increasing age (r = 0.43, P = 0.004). Despite the sero-epidemiological association of H. pylori infection with many inflammatory conditions, our data showed no such association for middle age asthmatic patients with mild intermittent asthma in our locality.
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Affiliation(s)
- K W Tsang
- University Department of Medicine, The University of Hong Kong, Queen Mary Hospital, SAR, China.
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Abstract
The recently reported increase in seroprevalence of Helicobacter pylori, the causative pathogen in peptic ulceration, in bronchiectasis is unexplained. Therefore, the association of antibodies directed against cytotoxin-associated gene A(CagA), whose expression indicates virulence of H. pylori, and upper gastrointestinal symptoms in patients with stable bronchiectasis and healthy volunteers evaluated. One hundred patients (mean +/- SD age 55.1+/-16.7 yrs) and 94 healthy asymptomatic subjects (54.6+/-7.6 yrs) underwent clinical and physiological assessment and serum levels of anti-H. pylori CagA were determined using standard clinical and enzyme-linked immunosorbent assay techniques. Samples were positive for anti-H. pylori CagA in 11.7% of controls and 24% of bronchiectatic subjects (p = 0.03). There was, however, no association between serum H. pylori CagA immunoglobulin G level and forced expiratory volume in one second (FEV1), forced vital capacity (FVC), sputum volume, respiratory symptoms or upper respiratory gastrointestinal symptoms (p>0.05). Patients who suffered from acid regurgitation or upper abdominal distension had significantly lower FEV1 and FVC (as a percentage of the predicted value) compared to their counterparts. The results of anticytotoxin-associated gene A measurements in this study contrasted with the previous finding that anti-Helicobacter pylori immunoglobulin G correlated with sputum volume. These findings, therefore, suggest that Helicobacter pylori, should it have a pathogenic role in bronchiectasis, could act via noncytotoxin-associated gene A-mediated mechanisms, and, in this context, gastro-oesophageal reflux might be of importance in bronchiectasis.
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Affiliation(s)
- K W Tsang
- University Dept of Medicine, The University of Hong Kong, Queen Mary Hospital, SAR
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Abstract
Obstructive sleep apnea (OSA) is found to affect 2-4% of the middle-aged population in several Caucasian studies, whereas the prevalence among other ethnic groups have not been clearly documented. It has been reported that OSA and systemic hypertension are highly associated; we therefore conducted a study on Chinese subjects who were receiving treatment for essential hypertension to assess the prevalence of OSA among this group. Ninety-two consecutive patients being followed up at a hypertension clinic were recruited for a questionnaire survey. The entire study group was aged 54.7 +/- 11.7 years, with 40 men. One male subject had a diagnosis of obstructive sleep apnea on nasal continuous positive airway pressure (nCPAP) treatment and 46 subjects agreed to an overnight sleep study. Those who underwent sleep study showed selection bias with a higher body mass index and more symptoms associated with OSA. Of the 46 who underwent sleep study, 16 (34.8%) had an obstructive apnea-hypopnea (AHI) score of >/=5 and excessive daytime sleepiness, with a median score of 26.2 (range, 8.3-64.9). Patients in the group with obstructive sleep apnea syndrome (OSAS) thus defined compared with those without OSAS had more men (64.7 vs 17.20%, p = 0.001) and an excess of smokers (31.5 vs 3.3%. p = 0.01) and had significantly more symptoms of excessive daytime sleepiness (p = 0.001), daytime fatigue (p = 0.007), and witnessed apneas (p = 0.008). Seven patients accepted treatment with nCPAP and reported improvement in symptoms, but there was no detectable change in clinic blood pressure measurements after 3 months of nCPAP treatment. This study demonstrated a high prevalence of previously unidentified OSAS among Chinese patients with essential hypertension. Increased awareness of both doctors and patients toward this potentially treatable problem is warranted.
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Affiliation(s)
- M Ip
- Department of Medicine, The University of Hong Kong, Queen Mary Hospital, Hong Kong, China
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Ooi GC, Chen FE, Chan KN, Tsang KW, Wong YH, Liang R, Chan V, Ngan H. Qualitative and quantitative magnetic resonance imaging in haemoglobin H disease: screening for iron overload. Clin Radiol 1999; 54:98-102. [PMID: 10050737 DOI: 10.1016/s0009-9260(99)91068-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVES To evaluate the clinical utility of magnetic resonance imaging (MRI) in screening for iron overload in non-transfusion dependent Haemoglobin (Hb) H disease. PATIENTS AND METHODS Thirty-six non-transfusion dependent HbH patients were evaluated with axial spin echo T1 and gradient echo T2 MRI of the abdomen and heart. The ratios of signal intensities (SIR) of the liver, spleen, pancreas and heart to paraspinous muscles were calculated. SIR <1 was taken as indicative of iron overload. Qualitative grading (0-4 scale) of iron overload was also performed. The relationship between T1 and T2 SIR and serum ferritin, and that between qualitative grading and serum ferritin were examined using standard statistical methods. Comparisons were also made between qualitative grading and quantitative T1 and T2 SIR data in diagnosing iron overload. Six patients underwent liver biopsies. RESULTS T2 SIR was more sensitive in detecting iron overload than T1 SIR. Thirty-three livers, 13 spleens, six pancreas and one heart were diagnosed as having iron overload with T2 SIR, including three patients with normal serum ferritin. A positive diagnosis by T2 SIR was more closely related to that of qualitative grading than T1 SIR. Serum ferritin was negatively correlated with hepatic SIR (T1 and T2), and with T2 SIR of the spleen and pancreas, even after adjustment for age. Liver haemosiderosis was confirmed in all six patients who underwent liver biopsies. Liver iron concentration of only one and a half times the normal was found in one patient with positive MR findings. CONCLUSION MR is a non-invasive, effective method for early detection of iron overload particularly in the liver and spleen. Qualitative grading and quantitative T2 SIR data are equivalent in diagnosing iron overload. Routine screening of non-transfusion dependent HbH patients will identify high risk patients in whom early therapeutic intervention may prevent further complications and morbidity.
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Affiliation(s)
- G C Ooi
- Department of Diagnostic Radiology, The University of Hong Kong, Queen Mary Hospital
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Abstract
Patients with bronchiectasis suffer from sputum production, recurrent exacerbations, and progressive airway destruction. Erythromycin is effective in diffuse panbronchiolitis, another suppurative airway disorder, although its efficacy is unknown in idiopathic bronchiectasis. A double-blind placebo-controlled study was therefore conducted to evaluate the effects of 8-week administration of low dose erythromycin (500 mg b.i.d.) in steady-state idiopathic bronchiectasis. Patients in the erythromycin group (n=11, 8 female, mean age 50+/-15 yrs), but not the placebo group (n=10, 8 female, mean age 59+/-16 yrs) had significantly improved forced expiratory volume in one second, forced vital capacity and 24-h sputum volume after 8 weeks (p<0.05). There was no parallel improvement in sputum pathogens, leukocytes, interleukin (IL)-1alpha and IL-8, tumour necrosis factor-alpha, or leukotriene B4. The results of this pilot study show that low-dose erythromycin improves lung function and sputum volume in bronchiectasis. Further studies are indicated to evaluate the efficacy of long-term erythromycin therapy in bronchiectasis.
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Affiliation(s)
- K W Tsang
- Dept of Medicine, The University of Hong Kong, Hong Kong
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Ho PL, Chan KN, Ip MS, Lam WK, Ho CS, Yuen KY, Tsang KW. The effect of Pseudomonas aeruginosa infection on clinical parameters in steady-state bronchiectasis. Chest 1998; 114:1594-8. [PMID: 9872194 DOI: 10.1378/chest.114.6.1594] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
STUDY OBJECTIVE To investigate the effect of Pseudomonas aeruginosa infection on clinical parameters in Chinese patients with noncystic fibrosis and steady-state bronchiectasis. DESIGN Prospective, cross-sectional clinicomicrobiological study with informed consent. SETTING Consecutive outpatient recruitment from a specialist bronchiectasis respiratory clinic. PATIENTS Outpatients (n = 100; 62 women; 55.1+/-16.7 years old; FEV1/FVC 1.4+/-0.7/2.1+/-0.9 L), who had stable respiratory symptoms for more than 3 weeks. MEASUREMENTS AND RESULTS Respiratory pathogens isolated from the sputum were: Pseudomonas aeruginosa (33), Haemophilus influenzae (10), Moraxella catarrhalis (2), other Gram-negative bacilli (5), Streptococcus pneumoniae (6), Staphylococcus aureus (5), mycobacteria (3), and yeast (1). Clinical parameters in patients with positive isolation of P aeruginosa were compared with those without the organism in the sputum culture (non-P aeruginosa). In the P aeruginosa group, the FEV1/FVC ratio and sputum volume were lower (p < 0.005) and higher (p < 0.0001), respectively, than those of the non-P aeruginosa group. The FEV1/FVC ratio (< 60%) and sputum volume (grading > 5) were independently associated with a positive sputum isolation of P aeruginosa with odds ratios of 3.1 (confidence interval [CI] 1.2 to 8.4; p < 0.01) and 4.7 (CI 1.6 to 13.3; p < 0.001), respectively. CONCLUSIONS P aeruginosa is the predominant respiratory pathogen isolated in the sputum of Chinese patients with steady-state bronchiectasis, and its isolation is associated with high sputum output (> or = 75th quartile) and moderately severe airflow obstruction (FEV1/FVC < 60%).
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Affiliation(s)
- P L Ho
- University Department of Microbiology, Queen Mary Hospital, The University of Hong Kong, Hong Kong
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Tsang KW, Ho PL, Lam WK, Ip MS, Chan KN, Ho CS, Ooi CC, Yuen KY. Inhaled fluticasone reduces sputum inflammatory indices in severe bronchiectasis. Am J Respir Crit Care Med 1998; 158:723-7. [PMID: 9730996 DOI: 10.1164/ajrccm.158.3.9710090] [Citation(s) in RCA: 106] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Although corticosteroid therapy might be clinically beneficial for bronchiectasis, very little is known of its effects on the inflammatory and infective markers in bronchiectasis. We have therefore performed a double-blind, placebo-controlled study to evaluate the effects of a 4-wk administration of inhaled fluticasone in bronchiectasis. Twenty-four patients (12 female; mean age 51 yr) were randomized into receiving either inhaled fluticasone (500 microgram twice daily) via the Accuhaler device (n = 12) or placebo. At each visit, spirometry, 24-h sputum volume, sputum leukocyte density, bacterial densities, and concentrations of interleukin (IL)-1beta, IL-8, tumor necrosis factor-alpha (TNF-alpha), and leukotriene B4 (LTB4) were determined. There was a significant (p < 0.05) decrease in sputum leukocyte density and IL-1beta, IL-8, and LTB4 after fluticasone treatment. The fluticasone group had one and the placebo group three episodes of exacerbation. There were no significant changes in spirometry (p > 0.05) or any reported adverse reactions in either group. The results of this study show that high-dose fluticasone is effective in reducing the sputum inflammatory indices in bronchiectasis. Large-scale and long-term studies are indicated to evaluate the effects of inhaled steroid therapy on the inflammatory components in bronchiectasis.
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Affiliation(s)
- K W Tsang
- University Departments of Medicine, Microbiology, Pediatrics, and Diagnostic Radiology, Queen Mary Hospital, The University of Hong Kong, Hong Kong
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Abstract
Soluble interleukin-2 receptor (IL-2R) concentrations were measured in 110 serum samples from 102 children undergoing routine small bowel biopsy for a wide range of gastrointestinal symptoms. Young children in the control group who had no gastrointestinal disease and a normal intestinal mucosa were found to have high concentrations of IL-2R. There was a significant inverse relationship between IL-2R concentration and age in the control group. Children with a gastrointestinal diagnosis appeared to have increased IL-2R concentrations, although some of the diagnostic groups were too small in size for statistical analysis. Children with cow's milk sensitive enteropathy had IL-2R concentrations equivalent to those of age-matched controls. High concentrations of IL-2R in young healthy children implies that serum IL-2R is of no clinical use as an index of inflammation in this age group.
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Affiliation(s)
- K N Chan
- Academic Department of Paediatric Gastroenterology, Queen Elizabeth Hospital for Children, London, UK
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Abstract
It has been suggested that endomysial antibodies are specific markers for coeliac disease. In a 13-month study, we examined the usefulness of screening for these antibodies in the diagnosis of coeliac disease in children. Twenty-one of 223 (9.4%) serum samples [or 17 of 192 (9%) children undergoing investigation for GI disorders] were found to be positive for serum IgA class endomysial antibodies. These included eight strong positives, eight positives, and five weak positives. One-hundred-thirty-four children had small bowel biopsies performed. Endomysial antibodies were found in all children with severe villous atrophy on a gluten-containing diet who were diagnosed as having coeliac disease. Three children with positive and four with weak-positive results did not have coeliac disease. One had partial villous atrophy consistent with the diagnosis of cow-milk-sensitive enteropathy and the others had a normal small bowel mucosa. This study confirms a strong association between endomysial antibodies and coeliac disease; however, not all cases with positive antibodies had the disease. At the present time, small bowel biopsy remains essential for the diagnosis of coeliac disease.
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Affiliation(s)
- K N Chan
- Academic Department of Paediatric Gastroenterology, Queen Elizabeth Hospital for Children, London, United Kingdom
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Chan KN, Phillips AD, Knutton S, Smith HR, Walker-Smith JA. Enteroaggregative Escherichia coli: another cause of acute and chronic diarrhoea in England? J Pediatr Gastroenterol Nutr 1994; 18:87-91. [PMID: 8126624] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
Enteroaggregative Escherichia coli (EAggEC) has been found to be associated with acute and persistent diarrhoea in children in developing countries. Its clinical significance in developed countries has not been examined in much detail. In a survey of faecal samples from children with diarrhoea presenting to a children's hospital in East London between August and December 1988, EAggEC strains were isolated in 8 of 297 (2.7%) consecutive stool samples collected from 289 children and in 5 of 34 typed E. coli isolates during 1988. Of the 13 children found to be excreting EAggEC, 8 had acute diarrhoea and 5 had chronic diarrhoea of more than 14 days' duration; 5 children had mixed infections. Compared to other organisms found during the same period, EAggEC were isolated as frequently as many other better-known pathogens such as enteropathogenic E. coli, Campylobacter, Salmonella, Shigella, Giardia lamblia, and Cryptosporidium. We conclude that EAggEC may be an important pathogen in developed countries.
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Affiliation(s)
- K N Chan
- Academic Department of Paediatric Gastroenterology, Queen Elizabeth Hospital for Children, London, England
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Chan KN, Phillips AD, Walker-Smith JA, Koskimies S, Spencer J. Density of gamma/delta T cells in small bowel mucosa related to HLA-DQ status without coeliac disease. Lancet 1993; 342:492-3. [PMID: 8102443 DOI: 10.1016/0140-6736(93)91616-t] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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Abstract
The effect of treatment with topical inhaled corticosteroids was assessed in 15 children of low birth weight (mean (SD) birth weight 1435 (268) g, gestational age 30.5 (2.9) weeks, age at study 8.2 (0.4) years) who were symptomatic and showed a positive airway response to histamine aerosol. The study was of a double blind, placebo controlled, crossover design with four week long treatment periods with inhaled beclomethasone dipropionate (400 micrograms daily) or placebo. Daily symptom scores were recorded and physiological measurements were performed at the beginning and end of each treatment period. There was no significant difference in respiratory symptom score, baseline airway function, or the airway response to histamine between treatment periods. The findings argue against an inflammatory basis for airway hyper-responsiveness in these children and raise questions as to its pathophysiological basis.
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Affiliation(s)
- K N Chan
- Department of Paediatrics and Neonatal Medicine, Royal Postgraduate Medical School, Hammersmith Hospital, London
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Silverman M, Chan KN. Lung function 8-18 years after intermittent positive pressure ventilation for hyaline membrane disease. Thorax 1991; 46:467. [PMID: 1858094 PMCID: PMC463204 DOI: 10.1136/thx.46.6.467-a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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Chan KN, Clay MM, Silverman M. Output characteristics of DeVilbiss No. 40 hand-held jet nebulizers. Eur Respir J 1990; 3:1197-201. [PMID: 2090484] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
DeVilbiss No. 40 hand-held nebulizers are widely used for quantifying airway responsiveness in large populations using pharmacological agents. We examined the aerosol characteristics of five nebulizers. Within each device, the aerosol output and droplet size were reasonably stable over a wide range of bulb pressures, although there were considerable differences in output characteristics between nebulizers. The droplet size was very large compared to conventional aerosol delivery systems, with a mass median diameter greater than 10 microns for three of the five devices. Between 28-50% of the output was in particles sufficiently small for airway deposition (less than 6.2 microns). A more vigorous compression of the bulb caused a small increase output and a reduction in droplet size, resulting in a much bigger variation in the output of the respirable aerosol (less than 6.2 microns) with changes in bulb pressure. The loss due to evaporation was about 3.5%, causing a similar rise in the osmolality of the nebulizer solution. In view of the variable nebulizer output and the marked between-operator variation in bulb pressure, the characteristics of individual DeVilbiss No. 40 nebulizers should be evaluated by individual operators before use in clinical practice or research.
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Affiliation(s)
- K N Chan
- Dept of Paediatrics and Neonatal Medicine, Royal Postgraduate Medical School Hammersmith Hospital, London, UK
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Chan KN, Clay MM, Silverman M. Output characteristics of DeVilbiss No. 40 hand-held jet nebulizers. Eur Respir J 1990. [DOI: 10.1183/09031936.93.03101197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
DeVilbiss No. 40 hand-held nebulizers are widely used for quantifying airway responsiveness in large populations using pharmacological agents. We examined the aerosol characteristics of five nebulizers. Within each device, the aerosol output and droplet size were reasonably stable over a wide range of bulb pressures, although there were considerable differences in output characteristics between nebulizers. The droplet size was very large compared to conventional aerosol delivery systems, with a mass median diameter greater than 10 microns for three of the five devices. Between 28-50% of the output was in particles sufficiently small for airway deposition (less than 6.2 microns). A more vigorous compression of the bulb caused a small increase output and a reduction in droplet size, resulting in a much bigger variation in the output of the respirable aerosol (less than 6.2 microns) with changes in bulb pressure. The loss due to evaporation was about 3.5%, causing a similar rise in the osmolality of the nebulizer solution. In view of the variable nebulizer output and the marked between-operator variation in bulb pressure, the characteristics of individual DeVilbiss No. 40 nebulizers should be evaluated by individual operators before use in clinical practice or research.
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Abstract
Twenty-seven children of very low birthweight (less than or equal to 1,500 g) whose lung function had been measured on several occasions during the first year were studied at the age of about 9 years. Fifteen of the children had received neonatal intermittent positive pressure ventilation, mostly for respiratory distress syndrome. Ten of the ventilated children were still oxygen dependent at 30 days of age. Compared to the remainder of the group, mechanically ventilated children had reduced lung compliance in early infancy and increased thoracic gas volume in the middle of their first year. These changes correlated with the level of neonatal respiratory therapy as indicated by the oxygen score. Lung compliance in early infancy, but not thoracic gas volume, correlated with forced expiratory volume at 1 second recorded at 9 years. On the other hand, reduced airway conductance showed no significant correlation with the neonatal oxygen score, but there was a strong correlation between airway conductance late in infancy and lung function at 9 years. This relationship was independent of neonatal mechanical ventilation. We conclude that perinatal factors, which may be associated with disturbed lung mechanics early in infancy, are only weak and indirect predictors of childhood lung function. Airway conductance late in infancy, determined by constitutional factors, prematurity itself or other undetermined factors, is a good predictor of airway function at 9 years.
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Affiliation(s)
- K N Chan
- Department of Paediatrics and Neonatal Medicine, Royal Postgraduate Medical School, Hammersmith Hospital, London, England
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Abstract
Lung function was recorded in a cohort of 130 age specific children of low birth weight (under 2000 g) and a reference population of 120 unselected local schoolchildren at 7 years of age. Children of the cohort were similar in height and forced vital capacity to the reference group, but had significantly reduced forced expiratory volume in 0.75 second and expiratory flow indices. Although neonatal respiratory illness was associated with reduced airway function, we were unable to confirm that this was a consequence of oxygen treatment or mechanical ventilation. Low birth weight, however, was closely associated with poor airway function independent of neonatal respiratory illness. Other factors of importance included the male gender and maternal smoking. The reduction in airway function observed in the low birthweight children was associated with cough but not wheeze. The disparity between the relatively well preserved vital capacity and reduced airway function suggests that very low birth weight, and hence prematurity, has its greatest effect on the subsequent growth of airway function. The absence of an association between neonatal oxygen score or mechanical ventilation and childhood lung function suggests that the long term effect of neonatal respiratory treatment is small compared with that of birth weight, maternal smoking, and male sex.
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Affiliation(s)
- K N Chan
- Department of Paediatrics and Neonatal Medicine, Royal Postgraduate Medical School, Hammersmith Hospital
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Abstract
We recorded the respiratory history by questionnaire in a 7 year old cohort of children whose birth weight was under 2000 g and an unselected reference group of local schoolchildren of the same age. Complete data were obtained in 121 low birthweight children (90% of those studied): 62 who had no neonatal respiratory illness, 25 who had oxygen treatment only, and 34 who received mechanical ventilation (of whom 10 had bronchopulmonary dysplasia). The low birthweight children were no more likely to wheeze than the reference group, but frequent and troublesome cough was significantly more common, especially among children of very low birth weight (under 1500 g) who had received neonatal respiratory treatment. Neonatal mechanical ventilation was not associated with increased symptoms when compared with neonatal oxygen treatment alone. The prevalence of cough at the age of 7 was independently associated with the level of neonatal intensive care as defined by oxygen score. Although there was no excess of wheeze in the cohort compared with the reference group, there was a weak correlation between wheeze and the neonatal oxygen score as well as with maternal smoking. Loss of schooling due to respiratory symptoms in the nine months before this study was no greater in children of low birth weight than in the reference group.
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Affiliation(s)
- K N Chan
- Department of Paediatrics and Neonatal Medicine, Royal Postgraduate Medical School, Hammersmith Hospital, London
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Chan KN, Silverman M. Lung function and bronchial responsiveness measured by forced oscillometry after bronchopulmonary dysplasia. Arch Dis Child 1989; 64:425-6. [PMID: 2705809 PMCID: PMC1791900 DOI: 10.1136/adc.64.3.425-a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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Abstract
We report a prospective study of airway responsiveness in a cohort of 121 children of low birthweight (under 2,000 g) at 7 years and a random sample of 100 local schoolchildren of the same age. A positive airway response was defined as a 20% fall in peak expiratory flow rate in response to a cumulative histamine dose of 3 mumol or less. We found a moderate increase in airway responsiveness to inhaled histamine in the cohort (44%) compared with the reference group (22%). There was no significant association between airway responsiveness and any perinatal variables including the level of respiratory support. The findings suggested that neonatal respiratory illness or its treatment did not play a major role in determining the long-term airway responsiveness in these children. Amongst all factors examined, reduced airway function at the age of 7 was most strongly associated with airway responsiveness, independent of perinatal and familial factors. Airway responsiveness was associated with significantly more chest symptoms. We suggest that increased airway responsiveness to inhaled histamine in low birthweight children is a consequence rather than the cause of reduced airway function and argue against the presence of any other form of airway dysfunction as a cause of airway responsiveness.
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Affiliation(s)
- K N Chan
- Department of Paediatrics and Neonatal Medicine, Royal Postgraduate Medical School, Hammersmith Hospital, London, England
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Abstract
In a prospective study on a cohort of 7 year old children of low birth weight (under 2000 g at birth), we observed an increased prevalence of airway responsiveness to histamine compared with a reference population of unselected, local schoolchildren. The airway responsiveness to histamine was significantly related to a history of asthma in first degree relatives (natural parents and siblings) in both groups of children, but not to that of the mothers. There was no increase in the prevalence of maternal asthma, a family history of asthma, or airway responsiveness in the mothers of low birthweight children. We were unable to find evidence to support the hypothesis that maternal smooth muscle irritability (uterine and airway) has a causative role in the premature labour in the mothers and in subsequent bronchial hyper-responsiveness in their prematurely born children.
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Affiliation(s)
- K N Chan
- Paediatric Department, Royal Postgraduate Medical School, Hammersmith Hospital, London
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Abstract
A new valveless ventilator, which uses an air jet to provide the driving force for positive pressure ventilation, was used on 13 newborn babies (10 of very low birthweight) who had severe respiratory disease. The ventilator differs from 'true' jet ventilators in that its driving gas does not take part in gas exchange. Functionally it is a pressure pre-set, time-cycled ventilator, whose performance is characterised by the rapid and precise maintenance of both inspiratory and expiratory airway opening pressure. All the babies had progressively worsening respiratory failure (mean values of arterial pCO2 were 9.46 kPa, with a pH of 7.14, and an inspired oxygen concentration of 92.5%) on conventional mechanical ventilation. On the new ventilator, with the same settings, there was a dramatic and highly significant improvement within 20 to 30 minutes (mean values of arterial pCO2 were 6.45 kPa, pH 7.26, and inspired oxygen concentration 85.7%). This improvement was maintained. The new ventilator represents an important advance in the management of babies with severe respiratory failure.
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Affiliation(s)
- K N Chan
- Department of Paediatrics, Royal Postgraduate Medical School, Hammersmith Hospital, London
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