Vitamin D receptor variants and uncontrolled asthma.

Summary: Background. Asthma is a common childhood respiratory disease, affecting around 20% of Irish children. In other populations, vitamin D receptor (VDR) polymorphisms have been associated with asthma risk. We aimed to investigate the association between 2 VDR polymorphisms and uncontrolled paediatric asthma. Methods. 44 asthmatic children and 57 healthy volunteers were studied. The VDR TaqI gene variant in exon 9 (T/C) (rs731236) and ApaI (rs7975232) in intron 8 (C/T) were determined, using TaqMan® Assays. The lung function, serum 25-hydroxyvitamin D (25OHD) levels and other biomarkers of allergy, immunity, airway and systemic inflammation were as-sessed. Results. The distribution of T and C alleles and genotype frequencies differed significantly between asthmatics and controls for both polymorphisms (p < 0.05). A significant association was found between both TaqI [OR = 2.37, 95% CI (1.27 - 4.45), p = 0.007] and ApaI polymorphisms, and asthma risk [OR = 2.93, 95% CI (1.62 - 5.3), p = 0.0004]. No association was observed between genotypes and 25OHD levels, lung function and other biomarkers, with the exception of Interleukin-10 (IL-10) and white blood cells count (WBC). IL-10 levels were lower in asthmatics with TC genotype for TaqI polymorphism (p < 0.01) and were higher in patients with TT genotype for ApaI (p < 0.01). WBC were higher in patients with TC and CC genotypes for TaqI (p < 0.05) and lower in TT genotype for ApaI (p < 0.05). Conclusion. TaqI and ApaI polymorphisms are associated with asthma in Irish children. Further studies are warranted to investigate the importance of decreased IL-10 levels in paediatric asthmatics with specific genotypes.

Diagnosis and treatment of sleep related breathing disorders in children: 2007 to 2011.

Sleep related breathing disorders (SRBD) have historically been under-recognised and under-treated. Obstructive sleep apnoea (OSA) affects approximately 3% of children. In line with the increased recognition of SRBD there has been an increase in demand for diagnostic services. We determined the awareness of SRBD amongst Irish paediatricians, examined the provision of sleep services to children throughout the country between 2007 and 2011 and audited diagnostic sleep services in a tertiary centre in 2011. Amongst respondents there was an awareness of SRBD but a poor understanding of diagnostic evaluation with 31/46 (67) referring to inappropriate services. There has been a sharp increase in both diagnostic sleep tests (433-1793 [414]) and in the use of non-invasive ventilation (NIV) (31-186 [627]) for treatment of SRBD between 2007 and 2011. Paediatric sleep services are organized in an ad-hoc manner nationally with significant service variation. The use of domiciliary overnight oximetry reduced the requirement for more formal polysomnography by 70%.

The changing epidemiology of the bronchiolitis epidemic in Tallaght Hospital.

Bronchiolitis affects one third of babies in their first year of life. We investigated all bronchiolitis admissions to Tallaght Hospital in the last five years, with the hope of providing an insight into the epidemic in an Irish population. We analysed these 1,202 admissions on the basis of time of year (busiest being December at 24.20%), length of stay (mean 2.92 days), gender (62% male) and age (mean 30.29 weeks). There was a 102% increase in the average incidence of bronchiolitis in the first six months of 2011 and 2012 (186) compared to the previous four years (92.25). P value was statistically significant at 0.0469. Our findings were backed up by comparable data from OLCH, Crumlin (149.5 for 2011-2012 vs 36.25 for 2007-2010). There has been in a significant shift in the timing and incidence of bronchiolitis in Tallaght Hospital in the last two years. We explored the possible reasons for this, with special attention to RSV incidence, climate causes and vaccine programs.

A decade of non-cystic fibrosis bronchiectasis 1996-2006.

This study aimed to determine the aetiology, clinical presentation, co-morbidity, severity and the lobar distribution of non cystic fibrosis bronchiectasis (NCFB). We performed a retrospective review of clinical, radiological, immunological and microbiological data from 92 non-CF patients with a High resolution thoracic CT (HRCT) diagnosis of bronchiectasis in the three Dublin Children's referral Hospitals for the period 1996-2006. Of 92 patients (50 female), the median age at diagnosis was 6.4 years. The aetiology of bronchiectasis was as follows; idiopathic 29 (32%), post-pneumonia 16 (17%), immune deficiency 15 (16%), recurrent aspiration 15 (16%), primary ciliary dyskinesia 8 (9%), chronic aspiration with immune deficiency 5 (5%), post foreign body inhalation 2 (2%), tracheomalacia 1 (1%) and Obliterative bronchiolitis 1 (1%). Bronchial asthma and gastroesophageal reflux disease (GORD) were concurrently present in 18 (20%) and 10 (11%) respectively. Left lower lobe was commonly involved followed next by the right middle lobe. The common isolates were Haemophilus influenza (50), Streptococcus pneumoniae (34) and Staphylococcus aureus (14), Moraxella catarrhalis (9) and Pseudomonas auerginosa (8). Surgical interventions were performed in 23 (25%) of patients, lobectomy 11 (12%), pneumectomy 2 (2%), laryngeal cleft repair 4 (5%), rigid bronchoscopy for foreign body removal 2 (2%), Nissan's fundoplication 2 (2%), tracheoesophageal fistula repair 2 (2%). We conclude NCFB is under-recognised in Irish children and diagnosis is often delayed and Bronchial Asthma and GORD are common co morbidity. A high index of suspicion and early HRCT can expedite the diagnosis.

Severe bone demineralisation is associated with higher mortality in children with cystic fibrosis.

Decreased bone mineral density (BMD) is an emerging problem for clinicians who care for children with Cystic fibrosis (CF). The aim of this study was to determine prevalence and assess risk factors for reduced BMD in our adolescent population with CF. All bone densitometry scans (n=99) performed on children (n=79) with a mean age 13.6 (10-19.2) years over a 7 year period (2000-2007) were reviewed. Patient records were reviewed for correlating clinical data. Low BMD is frequently present in adults and children with variable reports (36-66%). In our study, BMD expressed as z score of L2-L4 spine was reduced in a total of 50% children with a preponderance of males. Bone demineralization was strongly associated with increasing age (p=0.03), diminished lung function (p=0.027), reduced body mass index (p=0.001) and treatment with oral corticosteroids (p=0.02).

Voriconazole in the treatment of allergic bronchopulmonary aspergillosis in cystic fibrosis.

Allergic bronchopulmonary aspergillosis (ABPA) can cause a significant clinical deterioration in patients with cystic fibrosis. There is very little research in the current literature with regard to alternatives for treatment, apart from long courses of steroids. We conducted a retrospective review of all our patients with ABPA treated with the antifungal voriconazole and found there was a significant drop in IgE levels post treatment as well as a decrease in steroid dosing. The improvement in FEV was not statistically significant; however there was a very wide variation in pre-treatment levels.

Survey of the management of acute asthma in children.

Acute asthma is one of the most common reasons for children presenting to the emergency department. International guidelines for the management of acute paediatric asthma are widely available. In this study we examined how acute asthma in children is managed across hospitals in Ireland and compared Irish practice with standard international guidelines. We surveyed 54 paediatricians across 18 centres in Ireland. A total of 30 (55.5%) individual paediatricians across 17 (94%) centres replied. The majority of centres had a written protocol for the management of acute asthma. A large number of centres use MDI and spacer devices in acute management although doses used varied widely. Only 29% of centres had written asthma action plans available from the emergency department and 53% had plans available from the ward. Irish practice is largely inline with established guidelines. A national asthma strategy could further help to improve asthma care.

Postnatal development of the pattern of respiratory and cardiovascular response to systemic hypoxia in the piglet: the roles of adenosine.

1. In 3-day-old and 3-week-old spontaneously breathing piglets anaesthetized with Saffan, we have studied ventilatory and cardiovascular responses evoked by 5 min periods of hypoxia (breathing 10 and 6% O2). 2. In 3-day-old piglets both 10 and 6% O2 evoked an increase followed by a secondary fall in ventilation, a gradual tachycardia and a renal vasoconstriction, with an increase in femoral blood flow that was attributable to femoral vasodilatation. Arterial blood pressure rose initially but fell towards control values by the 5th minute of hypoxia. 3. The stable adenosine analogue 2-chloroadenosine (2-CA; 30 mg kg(-1) i.v.) evoked bradycardia and renal vasoconstriction, but had no effect on femoral vasculature. These responses were blocked by the adenosine receptor antagonist 8-phenyltheophylline (8-PT; 8 mg kg(-1) i.v.). 8-PT also abolished the secondary fall in ventilation evoked by 10 and 6% O2 and the renal vasoconstriction evoked by 10% O2, but had no effect on the tachycardia, or on the femoral vascular response. 4. By contrast, in 3-week-old piglets both 10 and 6% O2 evoked a sustained increase in ventilation, tachycardia and a rise in arterial pressure with renal vasoconstriction, but no change in renal blood flow and substantial femoral vasodilatation with an increase in femoral blood flow. 2-CA evoked bradycardia and renal vasoconstriction, as in 3-day-old piglets, but also evoked pronounced femoral vasodilatation. 8-PT blocked these responses and the hypoxia-induced femoral vasodilatation, but had no significant effect on other components of the hypoxia-induced response. 5. We propose that there is postnatal development of the ventilatory and cardiovascular responses evoked by systemic hypoxia and of the role of locally released adenosine in these responses: at 3 days, adenosine released within the central nervous system and within the kidney is a major contributor to the secondary fall in ventilation and renal vasoconstriction respectively, whereas at 3 weeks, adenosine makes little contribution to the ventilatory response, or renal vasoconstriction, but is largely responsible for hypoxia-induced vaso-dilatation in skeletal muscle.

Differentiation of the peripherally mediated from the centrally mediated influences of adenosine in the rat during systemic hypoxia.

In two groups of Saffan-anaesthetized, spontaneously breathing rats we have attempted to identify the peripheral influences of adenosine in mediating the responses evoked by hypoxia by using an adenosine receptor antagonist, 8-sulphophenyltheophylline (8-SPT, 20 mg kg-1 i.v., Group 1) and adenosine deaminase (ADA, 500 units in 0.04 ml infused into the tail artery for 10 min, Group 2); neither of these drugs crosses the blood-brain barrier. Recordings were made of respiration, heart rate, arterial pressure, blood flow and vascular conductance in the femoral artery, with ankle ligated (FBF and FVC, respectively) and in the carotid artery with all branches except the internal carotid ligated (CBF and CVC, respectively, Group 1 only) in order to indicate responses in skeletal muscle and cerebral vasculature. Hypoxia (breathing 8 or 10% O2 for 10 min) evoked an increase followed by a secondary decrease in respiration, tachycardia followed by secondary bradycardia, a fall in arterial pressure, an increase in FVC and CVC and an increase, followed by a decrease, in CBF. Neither 8-SPT nor ADA had any significant effect on the secondary decrease in respiration. The secondary bradycardia was unaffected by 8-SPT, but abolished by ADA. Both drugs reduced the fall in arterial pressure and the increase in FVC; 8-SPT had no significant effect on the increase in CVC, but CBF no longer fell with arterial pressure. We propose that adenosine contributes to the hypoxia-induced fall in arterial pressure by causing vasodilatation in skeletal muscle and possibly by causing bradycardia by a direct action on the heart; other evidence suggests that adenosine contributes to the secondary decrease in respiration by acting on central respiratory neurones. The possibility that the fall in arterial pressure and the secondary falls in CBF, respiration and heart rate, can become interdependent in a positive feedback manner is discussed.

The reflex ventilatory responses of conscious, newborn rats to alternations of inspiratory oxygen concentration.

We examined the effect of a dynamic, hypoxic stimulus upon the reflex respiratory responses of 15, conscious rat pups on post-natal days 5-7 in order to ascertain the influence of a non-adapting peripheral chemoreceptor discharge upon respiratory control during hypoxia in the newborn. Respiration was measured as integrated airflow into and out of a body plethysmograph. The respiratory response to 6 minutes of a 16-breath cycle (approximately 5 s) in FiO2 between 0.21 and 0.10 (alternating hypoxia) was compared with the response to 6 min of a constant FiO2 of 0.12 (non-alternating hypoxia). Ventilation increased significantly from a control level of 0.12 +/- 0.02 ml/s (mean +/- SEM) to 0.18 +/- 0.02 and 0.17 +/- 0.02 ml/s in non-alternating and alternating hypoxia runs respectively during the first minute (phase 1) of each run, after which ventilation in both run types fell progressively and significantly back towards control levels to reach, by the sixth minute (phase 2), 0.13 +/- 0.01 and 0.12 +/- 0.02 ml/s respectively. No significant difference was found between the levels of ventilation in non-alternating hypoxia and alternating hypoxia during either phase 1 (P greater than 0.10) or phase 2 (P greater than 0.60). No significant alternation was found in any respiratory variable at the frequency of the 16-breath hypoxic cycle during either phase 1 or phase 2 of non-alternating hypoxia. However, a significant alternation, at this frequency, of 37 +/- 6% (P less than 0.05 compared to control) was found in ventilation during phase 1 of alternating hypoxia which was further increased to 62 +/- 8% (P less than 0.05 compared to phase 1) during phase 2. In phase 1 the alternation was due primarily to significant alternation in inspiratory time whilst in phase 2 significant alternation also occurred in tidal volume, expiratory time and mean inspiratory flow. Our results show that the magnitude of hypoxic ventilatory depression (HVD) in the newborn is not affected by an alternating hypoxic stimulus and that, during phase 2, ventilation can still be stimulated by peripheral chemoreceptors. We suggest that peripheral chemoreceptor adaptation is unlikely to be a major cause of HVD in the newborn rat and that the magnitude of HVD is, in part, the result of a competitive interaction between peripheral chemoreceptor stimulation and a centrally-mediated inhibitory action of hypoxia.