The spectrum of sleep-disordered breathing symptoms and respiratory events in infants with cleft lip and/or palate

OBJECTIVE

To determine the prevalence of sleep-disordered breathing (SDB) symptoms and respiratory events during sleep in infants with cleft lip and/or palate (CL/P).

DESIGN

Prospective observational study.

SETTING

Cleft palate clinic, tertiary care paediatric hospital, before palate surgery.

PATIENTS

Consecutive newborn infants with CL/P.

MAIN OUTCOME MEASURES

Demographics, clinical history, sleep symptoms, facial measurement and polysomnography (PSG; sleep study) data.

RESULTS

Fifty infants completed PSG at 2.7±2.3 months; 56% were male, and 30% had a clinical diagnosis of Pierre Robin sequence (PRS) or a syndrome. The majority of infants (75%) were reported to snore frequently or constantly, while 74% were reported to have heavy or loud breathing during sleep. The frequency of parent-reported difficulty with breathing during sleep was 10% for infants with isolated CL/P, 33% for those with syndrome, and 43% for PRS (χ(2) 16.1, p<0.05). All infants had an Obstructive-Mixed Apnoea-Hypopnoea Index (OMAHI) >1 event/h, and 75% had an OMAHI >3 events/h. Infants with PRS had higher OMAHI (34.3±5.1) than infants with isolated CL/P (7.6±1.2) or infants with syndromes (15.6±5.7, F stat, p<0.001). Multivariate analysis showed that PRS was associated with higher OMAHI (B 0.53±0.22, p=0.022), but the majority of the variance for SDB was unexplained (constant B 1.31±0.55, p=0.024).

CONCLUSIONS

The results highlight that infants across the spectrum of CL/P have a high risk of SDB symptoms and obstructive respiratory events before palate surgery. Clinicians should enquire about symptoms of SDB and consider investigation with polysomnography in all infants with CL/P.

Expression of brain-derived neurotrophic factor and TrkB receptor in the sudden infant death syndrome brainstem

This study compared the expression of BDNF (proBDNF and rhBDNF forms) and its receptor TrkB, in the medulla of sudden infant death syndrome (SIDS) infants and infants who died from known causes (non-SIDS). This study also evaluated these markers in association with SIDS clinical risk factors including, sleep position, cigarette smoke exposure and gender. Brainstem tissue was immunohistochemically stained and quantitative analyses were made for eight nuclei of the caudal and rostral medulla. Compared to non-SIDS, SIDS infants had lower rhBDNF in the caudal nucleus of the solitary tract and higher TrkB in the caudal dorsal motor nucleus of the vagus. Within the SIDS cohort, prone sleep position was associated with lower rhBDNF in the caudal arcuate nucleus, and cigarette smoke exposure was associated with lower rhBDNF and TrkB in the inferior olivary nucleus. Abnormal expression of BDNF and TrkB suggests that neuroprotective functions of the BDNF/TrkB system may be reduced in respiratory-related nuclei of SIDS infants.

Effects of cigarette smoke exposure on nicotinic acetylcholine receptor subunits α7 and β2 in the sudden infant death syndrome (SIDS) brainstem

It is postulated that nicotine, as the main neurotoxic constituent of cigarette smoke, influences SIDS risk through effects on nicotinic acetylcholine receptors (nAChRs) in brainstem nuclei that control respiration and arousal. This study compared α7 and β2 nAChR subunit expression in eight nuclei of the caudal and rostral medulla and seven nuclei of the pons between SIDS (n=46) and non-SIDS infants (n=14). Evaluation for associations with known SIDS risk factors included comparison according to whether infants had a history of exposure to cigarette smoke in the home, and stratification for sleep position and gender. Compared to non-SIDS infants, SIDS infants had significantly decreased α7 in the caudal nucleus of the solitary tract (cNTS), gracile and cuneate nuclei, with decreased β2 in the cNTS and increased β2 in the facial. When considering only the SIDS cohort: 1-cigarette smoke exposure was associated with increased α7 in the vestibular nucleus and increased β2 in the rostral dorsal motor nucleus of the vagus, rNTS and Cuneate, 2-there was a gender interaction for α7 in the gracile and cuneate, and β2 in the cNTS and rostral arcuate nucleus, and 3-there was no effect of sleep position on α7, but prone sleep was associated with decreased β2 in three nuclei of the pons. In conclusion, SIDS infants demonstrate differences in expression of α7 and β2 nAChRs within brainstem nuclei that control respiration and arousal, which is independent on prior history of cigarette smoke exposure, especially for the NTS, with additional differences for smoke exposure (β2), gender (α7 and β2) and sleep position (β2) evident.

Effects of post-mortem intervals on regional brain protein profiles in rats using SELDI-TOF-MS analysis

Identification of disease-associated proteins is critical for elucidating CNS disease mechanisms and elaborating novel treatment strategies. It requires post-mortem tissue analysis which can be significantly affected by the collection process, post-mortem intervals (PMIs), and storage conditions. To assess the effect of time and storage conditions on brain protein stability, SELDI-TOF-MS protein profiles were assessed in rat frontal cortex, caudate-putamen, hippocampus and medulla samples collected after various PMIs (0, 6, 12, 24, 48, and 72 h) at 4 °C or at room temperature (RT) storage. Regions of interest were isolated from cryosections (tissue apposition, TA), or micropunched from cryosections apposed on filter paper (paper apposition, PA), and applied onto an NP20 ProteinChip array. Protein alterations, while greater at RT than at 4 °C, were detected at 6h then differentially evolved in the various brain regions, with greater alterations in the caudate-putamen (60%) and the cortex (48%). Overall, our sensitive analytical method allowed unveiling of different patterns of protein susceptibility to PMI and to storage temperature in the various brain regions. Some protein peaks were altered in all brain regions and may potentially serve as markers of the PMI status of the brain, or for reference values when studying new proteins. Changes in disease-related proteins within post-mortem samples can be greatly affected by PMI and storage conditions, particularly when studying fragile and/or low abundant protein/peptides in tissues sampled from the caudate-putamen and neocortex.

Immunolocalization of pro- and mature-brain derived neurotrophic factor (BDNF) and receptor TrkB in the human brainstem and hippocampus

Brain-derived neurotrophic factor (BDNF) and its receptor TrkB are essential in promoting normal development of the central nervous system. Specific functions that are affected in knockout models include respiratory control, coordination of movement and balance, and feeding activities. The expression of these markers has not yet been studied in the human infant brain. This study provides a detailed account of the distribution and localization of both pro- and mature-recombinant human (rh) forms of BDNF, and of TrkB in the human infant brainstem and hippocampus, and qualitatively compares this expression to that seen in the human adult. Using commercially available antibodies, we applied immunohistochemistry on formalin fixed and paraffin embedded human brain tissue [n=8 for infant, n=6 for adult], and qualitatively analyzed the expression of proBDNF, rhBDNF and TrkB. Amongst the brainstem regions studied, the greatest expression of the markers was in the mesencephalic trigeminal of the pons, and in the medulla, the inferior olive and arcuate nucleus. The lowest expression was in the substantia nigra of the midbrain and pontine locus coeruleus. Compared to adults, all the studied markers had a higher expression in the infant brainstem nuclei of the hypoglossal, vestibular, dorsal motor nucleus of the vagus, prepositus, cuneate, and dorsal raphe. In the hippocampus, only TrkB showed a higher expression in infants compared to adults. We conclude that BDNF and TrkB play important roles in controlling respiration, movement, balance and feeding in the brainstem and that the TrkB receptor is the most age-sensitive component of this system, especially in the hippocampus.

Genome-wide linkage of obstructive sleep apnoea and high-density lipoprotein cholesterol in a Filipino family: bivariate linkage analysis of obstructive sleep apnoea

Increasing evidence supports an association between obstructive sleep apnoea (OSA) and metabolic syndrome (MeS) in both children and adults, suggesting a genetic component. However, the genetic relationship between the diseases remains unclear. We performed a bivariate linkage scan on a single Filipino family with a high prevalence of OSA and MeS to explore the genetic pathways underlying these diseases. A large rural family (n = 50, 50% adults) underwent a 10-cM genome-wide scan. Fasting blood was used to measure insulin, triglycerides, total cholesterol and high density lipoprotein (HDL) cholesterol. Attended overnight polysomnography was used to quantify the respiratory disturbance index (RDI), a measure of sleep apnoea. Body mass index z-scores and insulin resistance scores were calculated. Bivariate multipoint linkage analyses were performed on RDI and MeS components. OSA prevalence was 46% (n = 23; nine adults, 14 children) in our participants. MeS phenotype was present in 40% of adults (n = 10) and 48% of children (n = 12). Linkage peaks with a logarithm of odds (LOD) score >3 were demonstrated on chromosome 19q13.4 (LOD = 3.04) for the trait pair RDI and HDL cholesterol. Candidate genes identified in this region include the killer cell immunoglobulin-like receptor genes. These genes are associated with modulating inflammatory responses in reaction to cellular stress and initiation of atherosclerotic plaque formation. We have identified a novel locus for genetic links between RDI and lipid factors associated with MeS in a chromosomal region containing genes associated with inflammatory responses.

The effects of nicotine on the alpha-7 and beta-2 nicotinic acetycholine receptor subunits in the developing piglet brainstem

Exposure to cigarette smoke is a major risk factor for sudden infant death syndrome (SIDS). We tested the hypothesis that nicotine increases expression of the nicotinic acetylcholine receptor (nAChR) subunits alpha7 and beta2 in a piglet model. Piglets exposed to 2mg/kg/day nicotine for 14 days postnatally (n=14) were compared to non-exposed controls (n=14), (equal gender proportions). Immunohistochemistry was performed to identify and quantify changes in, alpha7 and beta2 nAChR subunits in 8 nuclei of the medulla at both the rostral and caudal levels. Compared to controls, nicotine exposed piglets had decreased alpha7 in the rostral dorsal motor nucleus of the vagus (rDMNV) (p=0.01), and increased beta2 in the caudal DMNV (cDMNV) (p=0.05), caudal nucleus of the spinal trigeminal tract (cNSTT) (p=0.03) and caudal nucleus of the solitary tract (cNTS) (p=0.04). Analysis by gender showed that in the control group, compared to males, females had higher beta2 in the caudal hypoglossal (cXII) (p<0.01) and caudal inferior olivary (p=0.04) nuclei, while in the nicotine group females had higher beta2 in the cDMNV (p=0.02). Compared to control males, nicotine exposed males had lower beta2 in the cXII (p<0.01). Overall, changes in alpha7 were specific to nicotine exposure with no gender differentiation. Changes in beta2 were more widespread but showed gender-specific effects. These findings provide evidence that early postnatal exposure to nicotine significantly affects nAChR subunit expressions in the developing brainstem.

Adenotonsillectomy in the context of obstructive sleep apnoea

Adenotonsillectomy (T&A) is a common surgical procedure. Its frequency is highest in the paediatric age range and its most common current indication is obstructive sleep apnoea (OSA). Sleep studies are used to document the presence and severity of OSA. This review will focus on indications for and complications of T&A in the context of the age range and setting where this surgery is undertaken for OSA in children.

Evaluation of the pro-cognitive effects of the AMPA receptor positive modulator, 5-(1-piperidinylcarbonyl)-2,1,3-benzoxadiazole (CX691), in the rat

RATIONALE

Positive allosteric modulators of the glutamatergic alpha-amino-3-hydroxy-5-methyl-4-isoazolepropionic acid (AMPA) receptor do not stimulate AMPA receptors directly but delay deactivation of the receptor and/or slow its desensitisation. This results in increased synaptic responses and enhanced long-term potentiation. Thus, it has been suggested that such compounds may have utility for the treatment of cognitive impairment.

OBJECTIVES

The objective of the study was to investigate the effect of an AMPA positive modulator, CX691, (1) in three rodent models of learning and memory, (2) on neurochemistry in the dorsal hippocampus and medial prefrontal cortex following acute administration, and (3) on brain-derived neurotrophic factor (BDNF) messenger RNA (mRNA) expression in the rat hippocampus following acute and sub-chronic administration.

RESULTS

CX691 attenuated a scopolamine-induced impairment of cued fear conditioning following acute administration (0.1 mg/kg p.o.) and a temporally induced deficit in novel object recognition following both acute (0.1 and 1.0 mg/kg p.o.) and sub-chronic (bi-daily for 7 days) administration (0.01, 0.03, 0.1 mg/kg p.o.). It also improved attentional set-shifting following sub-chronic administration (0.3 mg/kg p.o.). Acute CX691 (0.1, 0.3 and 1.0 mg/kg, p.o.) increased extracellular levels of acetylcholine in the dorsal hippocampus and medial prefrontal cortex and dopamine in the medial prefrontal cortex. Sub-chronic administration of CX691 (0.1 mg/kg, p.o.) elevated BDNF mRNA expression in both the whole and CA(1) sub-region of the hippocampus (P < 0.05).

CONCLUSIONS

Collectively, these data support the pro-cognitive activity reported for AMPA receptor positive modulators and suggest that these compounds may be of benefit in treating disorders characterised by cognitive deficits such as Alzheimer's disease and schizophrenia.

Effects of acute intermittent hypercapnic hypoxia on insulin sensitivity in piglets using euglycemic clamp

Continuous hypoxia is associated with insulin resistance, altered glucose metabolism, and increased sympathetic nervous activity. This study examined the effect of 2 successive exposures to intermittent hypercapnic hypoxia (IHH) on glucose metabolism and insulin sensitivity in neonatal piglets. Piglets were assigned to 2 groups. One group was exposed to 2 x 90 minutes of hypercapnic hypoxia (8% O(2), 7% CO(2)), intermittently in 6-minute cycles alternating with 6-minute air. The second group was given 2 x 90 minutes of air. Blood pressure, blood gases, glucose, insulin, and lactate were measured during exposures. Insulin sensitivity was assessed using the euglycemic clamp before and after the exposures. Piglets in the IHH group exhibited reduced PO(2) (from 111.4 +/- 14.2 to 43.3 +/- 21.7), increased PCO(2) (from 33.6 +/- 1.9 to 49.4 +/- 5.4), and lactic acidosis. Compared with air, IHH decreased blood glucose (control [CON] 4.44 +/- 0.72 mmol/L vs IHH 2.67 +/- 1.2 mmol/L, P = .007), insulin (CON 12.5 +/- 7.4 microU/mL vs IHH 3.6 +/- 3.1 microU/mL, P = .03), and mean arterial pressure (CON 143.0 +/- 7.9 mm Hg vs IHH 112.5 +/- 9.5 mm Hg, P < .001) over 90 minutes. Maximal insulin-stimulated glucose disposal was not different between the groups on either day, nor was endogenous glucose production. Overall, exposure to hypoxia in an intermittent pattern reduced sympathetic drive as indicated by blood pressure and did not alter insulin sensitivity, resulting in decreases in blood glucose and insulin. We speculate that an intermittent hypoxic stimulus results in failure of initiation of compensatory responses to increased energy requirements that would usually be observed during sustained exposure to hypoxia.

Neuronal cell death in the Sudden Infant Death Syndrome brainstem and associations with risk factors

Immunoreactive expression of three cell death markers was quantitatively analysed in the human infant brainstem medulla. We assessed active caspase-3, TUNEL and single-stranded DNA (ssDNA) in a cohort of 92 infants, and analysed for: (i) variations in the immunoreactive expression with development; (ii) comparison of infants diagnosed with the Sudden Infant Death Syndrome (SIDS, n = 67) to infants who died suddenly with another diagnosis (non-SIDS, n = 25); and (iii) correlations with known clinical risk factors for SIDS. Five nuclei from the brainstem medulla (caudal and rostral levels) were studied, including the hypoglossal (XII), dorsal motor nucleus of the vagus (DMNV), the dorsal column nuclei (gracile and cuneate) and the arcuate nucleus. Our main hypothesis was that neuronal cell death would be increased in SIDS compared to non-SIDS infants, and the increase would correlate with risk factors such as prone sleeping and cigarette smoke exposure. Comparing SIDS to non-SIDS, there was an increase in caspase-3 in the rostral DMNV (P = 0.01), and a trend to increased TUNEL in the arcuate nucleus (P = 0.1), which was statistically significant when comparing the male SIDS to male non-SIDS cohort (P = 0.04). No major changes for ssDNA immunoreactivity were found. Moreover, TUNEL expression was affected by post-conceptional age, by sleep-related risk factors (predominantly affecting the dorsal column nuclei), and by cigarette smoke exposure in the rostral DMNV and arcuate nucleus. Active caspase-3 was affected by post-conceptional age but only in the XII, while gender-related differences were seen in the arcuate nucleus. This study provides further evidence of increased apoptosis in the brainstem of SIDS infants, but shows for the first time that these changes are also affected by age and gender, and by clinical risk factors such as the sleep position and cigarette smoke exposure.

Structural equation modeling of sleep apnea, inflammation, and metabolic dysfunction in children

Obstructive sleep apnea (OSA), often concomitant with obesity, increases the risk for the metabolic syndrome. One mechanism that may participate in this association is upregulation of inflammatory pathways. We used structural equation modeling to assess the interrelations between childhood obesity, OSA, inflammation, and metabolic dysfunction. One hundred and eighty-four children (127 boys, mean age: 8.5 +/- 4.1 years) had height and weight measured, underwent overnight polysomnography and had fasting blood taken. The blood was analyzed for insulin, glucose, lipids, leptin, and cytokines [interferon (IFN)-gamma, granulocyte macrophage-colony stimulating factor, interleukin (IL)-1beta, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12, tumor necrosis factor-alpha]. Structural equation modeling (SEM) was used to evaluate associations between the outcomes of interest including hypoxia, arousal (related to respiratory and spontaneous), obesity, metabolic dysfunction, and inflammatory markers. Two cytokine factors and one metabolic factor were derived for the SEM. These factors provided good fit in the structural equation model (chi(2)/df = 2.855; comparative fit index = 0.90, root mean squared error of approximation = 0.10) and all factor loadings were significantly different from zero (P < or = 0.01). Overall, our results indicate that while obesity (as measured by body mass index z-score) has a major influence on the metabolic dysfunction associated with OSA, arousal indices, and cytokine markers may also influence this association. Our results support the hypothesis that OSA is a contributor to the mechanisms that link sleep, systemic inflammation and insulin resistance, and show that the interrelations may begin in childhood.

The identification of children with cleft palate and sleep disordered breathing using a referral system

BACKGROUND

Cleft palate is associated with an increased risk of sleep disordered breathing (SDB) but the magnitude of this risk and specific risk factors are unclear. A better understanding of these components of risk will aid the early identification of SDB in this group of children.

OBJECTIVE

To describe the clinical characteristics and results of sleep studies undertaken in a cohort of children with cleft palate. Clinical features will be examined to determine potential associations with SDB in this group.

METHOD

A retrospective chart review was undertaken to ascertain sleep study results and clinical data for all children with cleft palate. Clinical features of interest included age, gender, syndrome diagnosis, cleft classification, and surgical status.

RESULTS

A total of 99 sleep studies were available from 62 children. The sample included a select group of children with cleft palate with features predictive of a high risk of SDB. Baseline sleep study results were consistent with SDB for 87% of children and 28% (15 of 54) of these children demonstrated severe SDB. Uni-variate analysis showed that age, syndrome, and surgical status had significant association with the severity of SDB. On multi-variate analysis only surgical status maintained this association, such that pre-palatoplasty/pharyngoplasty was associated with more severe SDB. Follow-up studies were completed in one-third of the cohort.

CONCLUSION

Children with cleft palate appear to have a significant risk of SDB. A prospective study of a population of children with cleft palate is needed to further define the characteristics of this risk and important risk factors.

The effect of acute intermittent hypercapnic hypoxia treatment on IL-6, TNF-alpha, and CRP levels in piglets

STUDY OBJECTIVES

Obstructive sleep apnea (OSA) is characterized by repeated episodes of upper-airway obstruction during sleep leading to significant hypercapnic hypoxic conditions. These conditions are associated with increased levels of proinflammatory cytokines (including interleukin [IL]-6, tumor necrosis factor [TNF]-alpha, and C-reactive protein [CRP]) and subsequent increased cardiovascular risk. It is unclear whether hypercapnic hypoxia itself causes inflammatory perturbations.

DESIGN

We evaluated circulating IL-6, TNF- a and CRP in a piglet model of infant OSA, following exposure to acute intermittent hypercapnic hypoxia (IHH). Study groups comprised of treatment (n = 8) and control (n = 8) groups. Treatment was two 90-minute sessions of IHH with arterial blood sampled before and after each IHH session.

MEASUREMENTS AND RESULTS

IL-6, TNF-alpha and CRP levels were measured before and after IHH treatment sessions. Results showed an increase in IL-6 following the first session of IHH that was neither sustained, nor repeated, during a subsequent exposure. Using mixed-modelling, TNF-alpha changed between time points and groups. There were no changes in CRP over the duration of the study.

CONCLUSION

These results suggest that acute hypoxia causes a transient increase in IL-6 levels and has implications for the pathogenesis of increased cardiovascular disease in OSA, especially in childhood.

Active caspase-3 in the sudden infant death syndrome (SIDS) brainstem

In a retrospective postmortem study, we examined the neuronal expression of active caspase-3, a specific apoptotic marker, in the brainstem of 67 infants dying from sudden infant death syndrome (SIDS), and 25 age-matched control infants (non-SIDS). Neuronal immunostaining for active caspase-3 was semi-quantitatively scored in nuclei from five brainstem levels: rostral, mid and caudal pons, and rostral and caudal medulla. Regardless of the cause of death (SIDS vs. non-SIDS), age-related differences in active caspase-3 expression were identified, predominantly in the medulla. No gender-related differences were identified. Comparing SIDS to non-SIDS cases, increased active caspase-3 expression was restricted to four nuclei in the caudal pons (abducens, facial, superior olivary, and pontine nuclei) and two nuclei in the rostral medulla (hypoglossal and dorsal motor nucleus of the vagus). We conclude that neuronal apoptosis is increased in the brainstem of SIDS compared to non-SIDS infants.

Changes in serotoninergic receptors 1A and 2A in the piglet brainstem after intermittent hypercapnic hypoxia (IHH) and nicotine

We studied the effects of intermittent hypercapnic hypoxia (IHH) and/or nicotine on the immunoreactivity of serotoninergic (5-HT) receptors 1A and 2A in the piglet brainstem. These exposures were developed to mimic two common risk factors for Sudden Infant Death Syndrome (SIDS); prone sleeping (IHH) and cigarette smoke exposure (nicotine). Immunoreactivity for 5-HT(1A)R and 5-HT(2A)R were studied in four nuclei of the caudal medulla. Three exposure groups were compared to controls (n=14): IHH (n=10), nicotine (n=14), and nicotine+IHH (n=14). In control piglets, the immunoreactivity of 5-HT(1A)R was highest in the hypoglossal nucleus (XII), followed by inferior olivary nucleus (ION), nucleus of the solitary tract (NTS) and dorsal motor nucleus of the vagus (DMNV), whereas for 5-HT(2A)R, the immunoreactivity was highest in DMNV/NTS and then ION. Compared to controls, IHH reduced 5-HT(1A)R immunoreactivity in all studied nuclei (p<0.05) but had no effect on 5-HT(2A)R immunoreactivity. Nicotine reduced 5-HT(1A)R immunoreactivity in the DMNV, ION and NTS (p<0.001), and reduced 5-HT(2A)R immunoreactivity in DMNV/NTS (p<0.05). Nicotine+IHH reduced 5-HT(1A)R in DMNV, ION and NTS (p<0.001) but had no effect on 5-HT(2A)R immunoreactivity. Effects of nicotine on the DMNV were more significant in males compared to the females. These results show for the first time that IHH and/or nicotine can reduce 5-HT receptor immunoreactivity within functionally important nuclei of the piglet medulla. The findings support our hypothesis that 5-HT receptor abnormalities may be caused by postnatal exposures to clinically-relevant stimuli such as cigarette smoke exposure and/or prone sleeping.

Outcome of noninvasive ventilation in children with neuromuscular disease

OBJECTIVE

To assess the effect of institution of noninvasive ventilation (NIV) on clinical outcome and quality of life (QOL) in a cohort of children with severe neuromuscular disorders.

METHODS

We reviewed records and obtained clinical data from the year prior to commencing NIV and annually thereafter. Data obtained included diagnosis, patient symptoms, mortality, NIV adverse effects, pulmonary function tests, polysomnographic data, length of hospitalizations, and health care costs. Patients and parents completed questionnaires assessing QOL with NIV and recalling QOL before NIV.

RESULTS

Fourteen of 17 (82%) suitable patients were enrolled. Follow-up ranged from 6 to 84 months (median 30). Symptoms of daytime sleepiness (p = 0.003) and headache (p = 0.046) improved after initiation of NIV. Sleep quality assessed by polysomnography also improved. Hospitalization rates (p = 0.002) and health care costs (p = 0.003) decreased. QOL remained stable after NIV, despite disease progression.

CONCLUSION

Treatment of respiratory failure, in children with neuromuscular disease, with noninvasive ventilation results in a reduction in symptoms, hospitalizations, and health care costs without adverse effects on quality of life.

N-methyl-d-aspartate receptor 1 changes in the piglet braintem after nicotine and/or intermittent hypercapnic-hypoxia

Prone sleeping and cigarette smoke exposure are two major risk factors for the sudden infant death syndrome (SIDS). Utilizing piglet models of early postnatal nicotine and/or intermittent hypercapnic-hypoxia (IHH) exposure, we tested the hypothesis that these exposures, separately or combined, increase N-methyl-D-aspartate (NMDA) receptor 1 (NR1) expression in the brainstem medulla. We also tested for gender-specific effects. Three piglet exposure groups were compared against 14 controls; 1, nicotine [n = 14], 2, IHH [n = 10], and 3, nicotine+IHH [n = 14], with equal gender proportions in each group. Non-radioactive in situ hybridization and immunohistochemistry were performed for NR1 mRNA and protein expression, respectively, and were quantified in seven nuclei of the brainstem medulla. NR1 mRNA was significantly increased in the gracile and inferior olivary nucleus (ION) after nicotine exposure, in five of seven nuclei after IHH exposure, and in three of seven nuclei after nicotine+IHH. The increased mRNA changes were accompanied by increased protein only in the ION after IHH and nicotine+IHH (P = 0.019, and P = 0.008 respectively). By gender, control females had greater NR1 mRNA than males in the dorsal motor nucleus of vagus (P = 0.05) and for protein in the ION (P = 0.02). This gender difference was maintained after nicotine exposure in the ION with additional gender differences observed including greater mRNA in the cuneate nucleus (P = 0.04) and nucleus of the spinal trigeminal tract (P = 0.03) of males compared with females. Overall, more changes occurred at the mRNA level than protein, and IHH exposure induced more changes than nicotine or nicotine+IHH exposures. Together, these findings suggest that hypercapnic-hypoxic exposures (modeling prone sleeping or sleep apnea) are more likely to induce NMDA receptor changes in the developing brainstem than nicotine exposure alone.

Obesity increases the risk for persisting obstructive sleep apnea after treatment in children

OBJECTIVE

To evaluate the impact of obesity at diagnosis on treatment outcomes in paediatric obstructive sleep apnea (OSA).

METHODS

Children were included if they had both diagnostic and follow-up studies for OSA. Anthropological and polysomnographic data were collected at the time of both studies. Polysomnograms were scored using standard criteria and OSA was defined as a respiratory disturbance index (RDI) >or=5. Obesity was defined as a body mass index standard deviation (z-)score (BMIsds) greater than 2, adjusted for age and gender.

RESULTS

For 69 children (49 males), mean age was 7.1+/-4.2 years and 29 (42%) children were obese. There was no significant difference in RDI between obese and non-obese children at diagnostic study. Following adenotonsillectomy the obese children had a significantly higher mean RDI (10.7+/-15.6 versus 3.7+/-4.3; p=0.01). Disease resolution occurred in 77.5% of non-obese compared to 45% of obese children (p=0.011). The odds ratio (OR) for persistent OSA in obese compared to non-obese children was 4.2 (95% CI: 1.5-11.9; p=0.005). Using initial RDI as a covariate, these data show that obesity in children has an adjusted OR for persistent OSA after adenotonsillectomy 3.7 (95% CI: 1.3-10.8, p=0.016).

CONCLUSION

For children, obesity at the time of diagnosis is a major risk for persisting OSA after treatment, regardless of the severity of initial disease.

Postnatal nicotine and/or intermittent hypercapnic hypoxia effects on apoptotic markers in the developing piglet brainstem medulla

The most important risk factors currently identified for the sudden infant death syndrome (SIDS) are prone sleeping and cigarette smoke exposure. In this study, we investigated the neuropathological sequelae of these risk factors by exposing piglets to intermittent hypercapnic-hypoxia (IHH) and/or nicotine (nic) in the early postnatal period. Our hypothesis was that either nic or IHH exposure could increase neuronal cell death, and that combined exposure (nic+IHH) would be additive. Four exposure patterns were studied: controls (n=14), IHH (n=10), nic (n=14), and nic+IHH (n=14). All groups had equal gender ratios. Nic exposure via an implanted osmotic minipump commenced within 48 h of birth and continued until age 13-14 days when animals were killed and brains collected. A total of 48 min of hypercapnic-hypoxia was delivered on the day immediately prior to killing in a pattern comprising 6 min of HH (8% O(2), 7% CO(2), balance N(2)) alternating with 6 min of air. Immunohistochemistry was performed to identify neurons positive for active caspase-3 and DNA fragmentation (terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling, TUNEL) in seven nuclei of the caudal medulla. Staining quantification showed that: 1. IHH induced neuronal death (increased both TUNEL and casapse-3) in more brainstem nuclei than nicotine. 2. Females were more severely affected by IHH than males. 3. Where IHH and nicotine were combined, TUNEL expression was approximately 5% less than IHH alone, but changes in caspase-3 were variable. We conclude that acute exposure to IHH in the postnatal period is more neurotoxic than exposure to nicotine alone. Combined exposure to IHH and nicotine produced variable responses with some results suggesting that nicotine can be neuroprotective. These results indicate that environmental insults attributable to prone sleeping can produce neurotoxic sequelae in SIDS, with some regional specificity in the response. However, no consistent relationship is evident when combining the two insults.

Follow-up on metabolic markers in children treated for obstructive sleep apnea

RATIONALE

In adults, obstructive sleep apnea (OSA) is associated with metabolic dysfunction that improves with treatment of OSA. No equivalent studies exist in children.

OBJECTIVE

To examine the relationship between metabolic markers and OSA with time and treatment in children.

METHODS

Metabolic markers measured on a fasting morning blood sample at diagnostic polysomnography and follow-up 1.3 +/- 0.6 yr later.

MEASUREMENTS AND MAIN RESULTS

Forty-five children (34 males), aged 6.9 +/- 3.5 yr, and including 12 obese subjects, were in the final analysis. There were no differences in metabolic markers between children with and without OSA at initial study; however, obese children had significantly higher insulin (106.1 +/- 72.1 vs. 66.7 +/- 37.6 pmol/L; p = 0.028), insulin/glucose ratio (23.7 +/- 14.3 vs. 14.7 +/- 8.0; p = 0.02), and significantly lower high-density lipoprotein cholesterol (1.3 +/- 0.2 vs. 1.6 +/- 0.4 nmol/L; p = 0.005) than nonobese children. Twenty children underwent surgical removal of adenotonsillar tissue, whereas 12 children with OSA elected not to have treatment. OSA persisted after treatment in five children, and resolved in 27. Thirteen children did not have OSA on initial or follow-up studies. At follow-up, there was a small but significant improvement in total cholesterol in those children whose OSA was resolved (4.8 +/- 0.8 to 4.7 +/- 0.6 nmol/L; p = 0.005) and a trend for obese children with persisting OSA to have elevated insulin levels compared with obese children without OSA (p = 0.07).

CONCLUSION

Obesity appears to be the major influence on metabolic dysfunction in children with OSA, but these preliminary data also suggest that resolution or persistence of OSA may affect changes in metabolic function over time.