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Biomedical subjects

A B Chang

Publications and source records attributed to A B Chang.

At least 37 records · Page 2Linked to original sources
PubMed2004

Inhaled anti-cholinergics for prolonged non-specific cough in children.

BACKGROUND: Non-specific cough is defined as non-productive cough in the absence of identifiable respiratory disease or known aetiology. It is commonly seen in paediatric practice. These children are treated with a variety of therapies including inhaled anti-cholinergic medications. OBJECTIVES: To determine the efficacy of inhaled anti-cholinergic medications in the management of prolonged non-specific cough in children. SEARCH STRATEGY: The Cochrane Register of Controlled Trials (CENTRAL), the Cochrane Airways Group Specialised Register and Cochrane Airways Group, MEDLINE and EMBASE databases were searched. Relevant pharmaceutical companies were contacted. The latest searches were performed in July 2003. SELECTION CRITERIA: All randomised controlled trials comparing inhaled anti-cholinergic medication with a placebo medication. DATA COLLECTION AND ANALYSIS: Results of searches were reviewed against pre-determined criteria for inclusion. No eligible trials were identified and thus no data were available for analysis. A single small trial in adults has been reported. MAIN RESULTS: No randomised-controlled trials that examined the efficacy of inhaled anti-cholinergic medications in the management of prolonged non-specific cough in children were found. REVIEWER'S CONCLUSIONS: There is currently no evidence to support the use of inhaled anti-cholinergics for symptomatic control of non-specific cough in children. Further research examining the effects of this intervention is needed.

Administration, Inhalation↗
PubMed2004

Snoring and its association with asthma in Indigenous children living in the Torres Strait and Northern Peninsula Area.

OBJECTIVE: Respiratory health of Indigenous and minority ethnic groups in affluent countries is poorer than their non-minority counterparts and sleep disorders are no exception. In children, obstructive sleep apnoea has the potential to result in serious long-term consequences. In 1999, we studied 1650 children and adolescents living in the Torres Strait and the Northern Peninsula Area, Australia. Here we report prevalence of snoring in these communities and relate its association with asthma symptoms. METHODS: A population-based cross-sectional study was conducted in the Torres Strait region. Five indigenous communities were randomly selected and information was collected using a structured face-to-face interview based on a standardized questionnaire. There was a 98% response rate, and 1650 children, 0-17 years of age, were included in the study. RESULTS: Overall, the prevalence of snoring was 14.2% (95% CI 12.5-15.9); 3.6% (95% CI 2.7-4.6) reported snorting, and 6% (95% CI 4.9-7.2) reported restless sleep. The prevalence of snoring was significantly higher among males (17.1% for males and 10.8 for females, P = 0.005). Children were five times more likely to have experienced snoring and snorting if they reported wheezing in the last 12 months. CONCLUSION: We conclude that the prevalence of symptoms suggestive of obstructive sleep problems is relatively high in children of this region. This highlights the need for awareness among the community patients and physicians about the problem of obstructive sleep-disordered breathing, especially in children with asthma, and for the need for further studies to measure prevalence of sleep breathing disorders among Indigenous Australians.

Adolescent↗
PubMed2003

Sequence and phylogenetic analyses of 4 TMS junctional proteins of animals: connexins, innexins, claudins and occludins.

Connexins and probably innexins are the principal constituents of gap junctions, while claudins and occludins are principal tight junctional constituents. All have similar topologies with four alpha-helical transmembrane segments (TMSs), and all exhibit well-conserved extracytoplasmic cysteines that either are known to or potentially can form disulfide bridges. We have conducted sequence, topological and phylogenetic analyses of the proteins that comprise the connexin, innexin, claudin and occludin families. A multiple alignment of the sequences of each family was used to derive average hydropathy and similarity plots as well as phylogenetic trees. Analyses of the data generated led to the following evolutionary and functional suggestions: (1) In all four families, the most conserved regions of the proteins from each family are the four TMSs although the extracytoplasmic loops between TMSs 1 and 2, and TMSs 3 and 4 are usually well conserved. (2) The phylogenetic trees revealed sets of orthologues except for the innexins where phylogeny primarily reflects organismal source, probably due to a lack of relevant organismal sequence data. (3) The two halves of the connexins exhibit similarities suggesting that they were derived from a common origin by an internal gene duplication event. (4) Conserved cysteyl residues in the connexins and innexins may point to a similar extracellular structure involved in the docking of hemichannels to create intercellular communication channels. (5) We suggest a similar role in homomeric interactions for conserved extracellular residues in the claudins and occludins. The lack of sequence or motif similarity between the four different families indicates that, if they did evolve from a common ancestral gene, they have diverged considerably to fulfill separate, novel functions. We suggest that internal duplication was a general evolutionary strategy used to generate new families of channels and junctions with unique functions. These findings and suggestions should serve as guides for future studies concerning the structures, functions and evolutionary origins of junctional proteins.

Amino Acid Sequence↗
PubMed2003

Non-CF bronchiectasis: clinical and HRCT evaluation.

Childhood bronchiectasis not related to underlying disease is still common in some populations in affluent countries. The aims of the study were to: 1) describe demographics, 2) evaluate the effectiveness of routine investigations, and 3) determine the relationship between spirometry and radiology scoring systems, in children with chronic suppurative lung disease (CSLD) living in Central Australia. Data of children living in Central Australia aged </=15 years with noncystic fibrosis CSLD were identified over 2 years. Chest high-resolution computed tomography (HRCT) scans were interpreted by a pediatric radiologist and scored according to three systems. Sixty-five children were identified, resulting in a prevalence of at least 14.7/1,000 aboriginal children aged </=15 years. Comorbidities (most common: suppurative otitis media in >70%) and early hospitalisation for pneumonia were common (median age, 0.5 years). Previous admissions for pneumonia were almost universally present and significantly more common than bronchiolitis (95% CI for proportional difference, 0.4-0.51). Although the majority did not have a treatable underlying cause, investigations had significant impact on management in 12.3% of children. None of the chest HRCT scores related to any spirometry data. In conclusion, CSLD is unacceptably common in indigenous children of this region, commences early in life, and is associated with significant comorbidities. Spirometry data do not reflect the severity of lung disease in HRCT scans. While improvement in the living standards is of utmost importance, the medical management that includes thorough investigations of these children should not be neglected.

Adolescent↗
PubMed2003

Altered arousal response in infants exposed to cigarette smoke.

AIMS: A failure of the arousal mechanism is a key feature in the apnoea theory for sudden infant death syndrome (SIDS). In infants studied at an age when the incidence of SIDS is highest, we evaluated whether in utero smoke exposed infants have altered arousal response to standardised auditory stimuli, and/or sleep pattern, as recorded on overnight complex sleep polysomnography. METHODS: A standardised sequence of audiology stimuli was applied binaurally to 20 in utero smoke and non-smoke exposed infants aged 8-12 weeks during a rapid eye movement (REM) and NREM epoch, in a controlled (temperature, position, pacifier use, noise) sleep environment. Infants were monitored for 10-12 hours using complex sleep polysomnography. RESULTS: Five infants exposed to in utero tobacco smoke did not have behavioural arousal response, whereas all non-smoke exposed infants aroused during NREM (p = 0.016). There was, however, no difference in REM sleep, and the groups did not differ in routine overnight complex sleep polysomnography parameters. CONCLUSION: At the age when the incidence of SIDS is at its peak, infants of smoking mothers are less rousable than those of non-smoking mothers in NREM sleep; this may partly explain why such infants are more at risk of SIDS.

Adult↗
PubMed2003

Relation between measurements of cough severity.

BACKGROUND: In asthma, measurements of airway inflammation correlate poorly with clinical markers and airway hyperresponsiveness. While the relation between determinants of asthma severity is known, that for cough is unknown. We hypothesised that cough sensitivity changes relate to changes in cough scores and objectively measured cough frequency. AIMS: To examine the relation between commonly used outcome measurements of cough severity in children. METHODS: The concentration of capsaicin causing two and five or more coughs (C2 and C5 respectively), cough frequency objectively measured using an ambulatory cough meter, and parent and child recorded subjective cough scores were determined in 40 children with recurrent cough on two occasions. RESULTS: On occasion one, log cough frequency significantly correlated with parent and child recorded log cough score (r(s) = 0.32, p = 0.05; and r(s) = 0.32, p = 0.046 respectively) and significantly negatively correlated with log C2 (r(s)= -0.5, p = 0.005). Subjective cough scores did not relate to either C2 or C5. On occasion two, the relation between cough frequency and C2 and C5 measures was lost, but C2 had a weak but significant relation to parent recorded cough score (r(s) = -0.38, p = 0.047). When the changes in the log values were determined, C5 but not C2 significantly related to cough frequency. CONCLUSION: In children, measures of cough sensitivity have a weak relation with cough frequency. Subjective cough scores have a stronger and consistent relation with cough frequency. These cough severity indices measure different aspects of cough. The choice of indices depends on the reason for performing the measurement.

Adolescent↗
PubMed2002

Series of laryngomalacia, tracheomalacia, and bronchomalacia disorders and their associations with other conditions in children.

Laryngomalacia, bronchomalacia, and tracheomalacia are commonly seen in pediatric respiratory medicine, yet their patterns and associations with other conditions are not well-understood. We prospectively video-recorded bronchoscopic data and clinical information from referred patients over a 10-year period and defined aspects of interrelationships and associations. Two hundred and ninety-nine cases of malacia disorders (34%) were observed in 885 bronchoscopic procedures. Cough, wheeze, stridor, and radiological changes were the most common symptoms and signs. The lesions were most often found in males (2:1) and on the left side (1.6:1). Concomitant malacia lesions ranged from 24% for laryngotracheobronchomalacia to 47% for tracheobronchomalacia. The lesions were found in association with other disorders such as congenital heart disorders (13.7%), tracheo-esophageal fistula (9.6%), and various syndromes (8%). Even though the understanding of these disorders is in its infancy, pediatricians should maintain a level of awareness for malacia lesions and consider the possibility of multiple lesions being present, even when one symptom predominates or occurs alone.

Adolescent↗
PubMed2002

Therapy for cough: active agents.

Cough is an important defensive reflex of the upper airway and is also a very common symptom of respiratory disease. Cough after an upper respiratory virus infection is transient, and persistent cough is associated with a whole range of conditions such as asthma, rhino-sinusitis, gastro-oesophageal reflux. Treatment directed at these conditions may improve the associated cough. There is often a need, however, to control cough itself, whatever the cause. The most effective drugs in this class are the opioids, such as morphine, codeine or pholcodeine, but at effective doses they have side-effects such as drowsiness, nausea, constipation and physical dependence. Investigations into the cough reflex and into the potential mechanisms of sensitised cough reflex have uncovered several potential targets for novel drugs. New opioids such as k- and d-receptor agonists apart from m-agonists have been developed, in addition to non-opioid, nociceptin. Neurokinin receptor antagonists, bradykinin receptor antagonists, vanilloid receptor VR-1 antagonists may be beneficial by blocking effects of tachykinins, and sensory nerve activation. Local anaesthetics, blockers of sodium-dependent channels, and maxi-K CA2+-dependent channel activators of afferent nerves are inhibitors of the cough reflex. Some of these novel agents may act centrally or peripherally or at both sites as antitussives. Large scale trials of these novel compounds have not been tried in cough in man, but there is a serious need for more effective antitussives devoid of side-effects.

Antitussive Agents↗
PubMed2002

Persistent cough in children and the overuse of medications.

OBJECTIVE: Children referred for persistent cough were evaluated for the referring and final diagnosis, and the extent of the use of medications prior to referral and the side effects encountered. METHODS: Data on children seen by respiratory paediatricians for persistent cough (> or =4 weeks) in a tertiary respiratory setting were collected prospectively over 12 months. RESULTS: Of the 49 children, 61.2% were diagnosed with asthma at referral, with similar referral rates from general practitioners and paediatricians. Children with isolated cough were just as likely to have been diagnosed with asthma as children with cough and wheeze. Medication use (asthma, gastro-oesophageal reflux and antibiotics) prior to referral was high, asthma medications were most common, and of these 12.9% had significant steroid side effects. The most common abnormality found (46.9%) was a bronchoscopically defined airway lesion, and in 56.5% of these children, another diagnosis (aspiration, achalasia, gastro-oesophageal reflux) existed. No children had a sole final diagnosis of asthma and pre-referral medications were weaned in all children. CONCLUSION: Over diagnosis of asthma and the overuse of asthma treatments with significant side effects is common in children with persistent cough referred to a tertiary respiratory clinic. Children with persistent cough deserve careful evaluation to minimize the use of unnecessary medications and, if medications are used, assessment of response to treatment is important.

Adolescent↗
PubMed2002

Cough, airway inflammation, and mild asthma exacerbation.

BACKGROUND: Prospective data on the temporal relation between cough, asthma symptoms, and airway inflammation in childhood asthma is unavailable. AIMS AND METHODS: Using several clinical (diary, quality of life), lung function (FEV(1), FEV(1) variability, airway hyperresponsiveness), cough (diary, cough receptor sensitivity (CRS)), and inflammatory markers (sputum interleukin 8, eosinophilic cationic protein (ECP), myeloperoxidase; and serum ECP) of asthma severity, we prospectively described the course of these markers in children with asthma during a non-acute, acute, and resolution phase. A total of 21 children with asthma underwent these baseline tests; 11 were retested during days 1, 3, 7, and 28 of an exacerbation. RESULTS: Asthma exacerbations were characterised by increased asthma and cough symptoms and eosinophilic inflammation. Sputum ECP showed the largest increase and peaked later than clinical scores. Asthma scores consistently related to cough score only early in the exacerbation. Neither CRS nor cough scores related to any inflammatory marker. CONCLUSION: In mild asthma exacerbations, eosinophilic inflammation is dominant. In asthmatic children who cough as a dominant symptom, cough heralds the onset of an exacerbation and increased eosinophilic inflammation, but cough scores and CRS do not reflect eosinophilic airway inflammation.

Acute Disease↗
PubMed2002

Bronchoscopic findings in children with non-cystic fibrosis chronic suppurative lung disease.

BACKGROUND: Published data on the frequency and types of flexible bronchoscopic airway appearances in children with non-cystic fibrosis bronchiectasis and chronic suppurative lung disease are unavailable. The aims of this study were to describe airway appearances and frequency of airway abnormalities and to relate these airway abnormalities to chest high resolution computed tomography (cHRCT) findings in a cohort of children with non-cystic fibrosis chronic suppurative lung disease (CSLD). METHODS: Indigenous children with non-cystic fibrosis CSLD (>4 months moist and/or productive cough) were prospectively identified and collected over a 2.5 year period at two paediatric centres. Their medical charts and bronchoscopic notes were retrospectively reviewed. RESULTS: In all but one child the aetiology of the bronchiectasis was presumed to be following a respiratory infection. Thirty three of the 65 children with CSLD underwent bronchoscopy and five major types of airway findings were identified (mucosal abnormality/inflammation only, bronchomalacia, obliterative-like lesion, malacia/obliterative-like combination, and no macroscopic abnormality). The obliterative-like lesion, previously undescribed, was present in 16.7% of bronchiectatic lobes. Structural airway lesions (bronchomalacia and/or obliterative-like lesion) were present in 39.7% of children. These lesions, when present, corresponded to the site of abnormality on the cHRCT scan. CONCLUSIONS: Structural airway abnormality is commonly found in children with post-infectious bronchiectasis and a new bronchoscopic finding has been described. Airway abnormalities, when present, related to the same lobe abnormality on the cHRCT scan. How these airway abnormalities relate to aetiology, management strategy, and prognosis is unknown.

Adolescent↗
PubMed2001

Application of chest high-resolution computer tomography in young children with cystic fibrosis.

SUMMARY. High-resolution computed tomography (HRCT) of the chest permits early detection of lung disease; two relevant scoring systems (Bhalla and Nathanson) have been developed to describe CF lung disease. Comparisons between the two scoring systems have not been made, and it is not known which system is more appropriate for young children, i.e., the age group where other objective markers are scarce. We reviewed the clinical findings, pulmonary function data, and HRCT of 16 children aged less than 12 years. The Bhalla scoring system had a better correlation with FEV(1) (r = -0.65, P = 0.012) than the Nathanson score (r = 0.53, P = 0.05). All children had bronchiectasis, including 5 with normal pulmonary function tests. The lower lobes were universally involved, and 5 children did not have any upper lobe disease. Four of these 5 children were aged less than 7 years. We conclude that the Bhalla scoring system is more applicable to young children than is the Nathanson system. Also, in this group of young children with CF, lower lobes are more commonly involved than upper lobes, which is in contrast to the classical teaching that CF lung disease begins in the upper lobes.

Age Factors↗
PubMed2001

Frequency and perception of cough severity.

OBJECTIVE: The frequency of the common symptom of cough in children is unknown. The aim of this study was to compare cough frequency and perception of cough severity in children with and without recurrent cough. METHODOLOGY: Eighty-four children with (C) and without (NC) recurrent cough were recruited in the same season. Cough frequency (measured with cough-meter) and subjective cough severity (measured on parent-completed and child-completed diary cards on two subjective systems), were compared between the two groups. RESULTS: Cough frequency in C (median 65/day) was significantly higher than in NC (10/day). The correlation between daytime and night-time cough was higher in NC (rs = 0.51, P < 0.00001) than in C (rs = 0.3, P = 0.05). The C group had significantly higher coughs per score than NC, for both subjective methods. CONCLUSIONS: Children with recurrent cough have a higher frequency and different pattern of cough than controls enrolled in the same season. Subjective perception of cough severity is dependent on the population studied.

Adolescent↗
PubMed2001

A review of cough in children.

Cough is a very common symptom of respiratory disease and reason for parents to seek medical attention. The article presents broad clinical guidelines on the approach to childhood cough and discusses current controversies of the management of cough in children.

Adult↗
PubMed2001

High prevalence of asthma in five remote indigenous communities in Australia.

Data on the prevalence of asthma in children residing in remote indigenous communities in Australia are sparse, despite the many reports of high prevalence in nonindigenous children of this country. Two previous Australian studies have had poor participation rates, limiting interpretation of their results. A study of children in the Torres Strait and Northern Peninsula Area of Australia was conducted to document the prevalence of asthma symptoms. Five indigenous communities were randomly selected and trained interviewers, who were local indigenous health workers, recruited participants using a house-by-house approach. Information was collected by a structured face-to-face interview based on a standardized questionnaire constructed from the protocol International Study of Asthma and Allergy in Childhood; 1,650 children were included in the study with a 98% response rate. Overall, the prevalence of self-reported ever wheezing was 21%; 12% reported wheezing in the previous year; and 16% reported ever having asthma. There was significant variation in the prevalence of asthma symptoms between communities. It is concluded that there are significant intercommunity variations in the prevalence of asthma symptoms in remote communities and that the prevalence in these communities is as high as in nonindigenous groups.

Adolescent↗
PubMed2000

Cough in children.

Cough is a common presenting problem in children. A persistent moist or productive cough is always abnormal. The history, examination, chest x-ray and spirometry usually provide clues to specific causes of cough. Non-specific cough, defined as a non-productive or dry cough in the absence of identifiable respiratory disease, is poorly understood. We briefly discuss major controversies in non-specific cough and its management in children.

Child↗