Plant roots but not hydrology control microbiome composition and methane flux in temperate fen mesocosms.

The rewetting of formerly drained peatlands can help to counteract climate change through the reduction of CO2 emissions. However, this can lead to resuming CH4 emissions due to changes in the microbiome, favoring CH4-producing archaea. How plants, hydrology and microbiomes interact as ultimate determinants of CH4 dynamics is still poorly understood. Using a mesocosm approach, we studied peat microbiomes, below-ground root biomass and CH4 fluxes with three different water level regimes (stable high, stable low and fluctuating) and four different plant communities (bare peat, Carex rostrata, Juncus inflexus and their mixture) over the course of one growing season. A significant difference in microbiome composition was found between mesocosms with and without plants, while the difference between plant species identity or water regimes was rather weak. A significant difference was also found between the upper and lower peat, with the difference increasing as plants grew. By the end of the growing season, the methanogen relative abundance was higher in the sub-soil layer, as well as in the bare peat and C. rostrata pots, as compared to J. inflexus or mixture pots. This was inversely linked to the larger root area of J. inflexus. The root area also negatively correlated with CH4 fluxes which positively correlated with the relative abundance of methanogens. Despite the absence or low abundance of methanotrophs in many samples, the integration of methanotroph abundance improved the quality of the correlation with CH4 fluxes, and methanogens and methanotrophs together determined CH4 fluxes in a structural equation model. However, water regime showed no significant impact on plant roots and methanogens, and consequently, on CH4 fluxes. This study showed that plant roots determined the microbiome composition and, in particular, the relative abundance of methanogens and methanotrophs, which, in interaction, drove the CH4 fluxes.

Risk factors for sleep-related hypoxia in primary school children.

Sleep-related hypoxia has adverse effects on cognition in children. Knowledge of factors contributing to sleep-related hypoxia is sparse. We aimed to identify demographic and clinical factors associated with mild (nadir arterial oxygen saturation 91-93%), moderate (nadir arterial oxygen saturation 3.9) sleep-related hypoxia in children. Parental questionnaires were distributed and overnight recordings of arterial oxygen saturation performed in a population-based cross-section of primary school children (n = 995). Associations were determined using unconditional logistic regression as well as unadjusted and adjusted odds ratios (OR), and their 95% confidence intervals (95% CI) calculated. Male sex, overweight (i.e., body mass index >or= 75th percentile), household smoking, symptoms of sleep-disordered breathing, a current respiratory tract infection, and histories of asthma and respiratory allergy were all significantly associated with sleep-related hypoxia. In multiple regression analysis, (i) overweight (OR, 95% CI: 2.7, 1.7-4.3) and a history of respiratory allergy (1.7, 1.1-2.7) were independent risk factors for mild sleep-related hypoxia, (ii) overweight (3.2, 1.7-5.8), a history of respiratory allergy (2.4, 1.4-4.4), and household smoking >10 cigarettes/day (1.8, 1.1-2.8) were independent risk factors for moderate sleep-related hypoxia, and (iii) overweight (2.3, 1.04-5.3), a history of respiratory allergy (2.5, 1.2-5.1), and a current respiratory tract infection (4.4, 2.0-9.8), were independent risk factors for recurrent sleep-related hypoxia. Our data suggest that overweight, passive smoking, respiratory allergies, and acute lung disease may independently contribute to sleep-related hypoxia in children.

Sleep problems and daytime somnolence in a German population-based sample of snoring school-aged children.

Habitual snoring is associated with daytime symptoms like tiredness and behavioral problems. Its association with sleep problems is unclear. We aimed to assess associations between habitual snoring and sleep problems in primary school children. The design was a population-based cross-sectional study with a nested cohort study. The setting was twenty-seven primary schools in the city of Hannover, Germany. Habitual snoring and sleep problems were assessed in primary school children using an extended version of Gozal's sleep-disordered breathing questionnaire (n = 1144). Approximately 1 year later, parents of children reported to snore habitually (n = 114) and an equal number of children who snored never or occasionally were given the Sleep Disturbance Scale for Children, a validated questionnaire for the assessment of pediatric sleep problems. Snoring status was re-assessed using the initial questionnaire and children were then classified as long-term habitual snorers or ex-habitual snorers. An increasing prevalence of sleep problems was found with increasing snoring frequency for sleep-onset delay, night awakenings, and nightmares. Long-term habitual snorers were at significantly increased risk for sleep-wake transition disorders (e.g. rhythmic movements, hypnic jerks, sleeptalking, bruxism; odds ratio, 95% confidence interval: 12.0, 3.8-37.3), sleep hyperhidrosis (3.6, 1.2-10.8), disorders of arousal/nightmares (e.g. sleepwalking, sleep terrors, nightmares; 4.6, 1.3-15.6), and excessive somnolence (i.e. difficulty waking up, morning tiredness, daytime somnolence; 6.3, 2.2-17.8). Ex-habitual snorers were at increased risk for sleep-wake transition disorders (4.4, 1.4-14.2). Habitual snoring was associated with several sleep problems in our study. Long-term habitual snorers were more likely to have sleep problems than children who had stopped snoring spontaneously.

Habitual snoring, intermittent hypoxia, and impaired behavior in primary school children.

OBJECTIVES: Sleep-disordered breathing is associated with impaired behavior and poor academic performance in children. We aimed to determine the extent of behavioral problems in snoring children, clarify the role of intermittent hypoxia, and test the reversibility of impaired behavior and poor academic performance. METHODS: In 1144 children, habitual snoring (HS; snoring frequently or always) and impaired behavior were assessed using parental questionnaires. Intermittent hypoxia (ie, presence of > or =5 arterial oxygen desaturations by > or =4% or > or =1 desaturation to < or =90%) was investigated with pulse oximetry. Poor academic performance (grade 4-6 on a 6-point scale in mathematics, science, or spelling) was based on the last school report. HS, impaired behavior, and academic performance were reevaluated after 1 year. Adjusted odds ratios (ORs) were calculated using unconditional logistic regression. RESULTS: HS was significantly associated with hyperactive (OR: 2.4) and inattentive behavior (OR: 4.0), daytime tiredness (OR: 7.1), and sleepiness (OR: 2.6-4.8). These associations were independent of intermittent hypoxia. HS was also significantly associated with bad conduct (OR: 2.8), emotional symptoms (OR: 5.5), and peer problems (OR: 9.7). At follow-up, hyperactive and inattentive behavior but not academic success had significantly improved in children in whom HS had ceased. CONCLUSIONS: We suggest that impaired behavior is a key feature of HS independent of intermittent hypoxia and improves when HS ceases.

Risk factors and natural history of habitual snoring.

STUDY OBJECTIVE: It has been suggested that habitual snoring (HS) has adverse health outcomes in children. We aimed to identify risk factors for HS and determine its natural history in primary school children. DESIGN: Cross-sectional, population-based cohort study. SETTING: Twenty-seven primary schools located within the city limits of Hannover, Germany. PARTICIPANTS: Third-grade primary school children. MEASUREMENTS AND RESULTS: Snoring frequency and potential risk factors were investigated using parental questionnaires. Unadjusted and adjusted odds ratios (ORs) for HS and their 95% confidence intervals (CIs) were calculated. One year after the initial contact, snoring status was re-evaluated in habitual snorers. In total, 1,760 children were contacted, and 1,144 parents and their children (49% were girls) agreed to participate and returned a completed questionnaire. A body mass index >/= 90th percentile (OR, 3.5; 95% CI, 1.8 to 7.1), low maternal education (OR, 2.3; 95% CI, 1.1 to 4.7), regular daytime mouth breathing (OR, 7.4; 95% CI, 3.5 to 15.6), and a higher frequency of sore throats (OR, 17.6; 95% CI, 6.4 to 48.8) were independent risk factors for HS. Parental smoking and frequent infections were significantly but not independently associated with HS. The association of low maternal education and HS was higher in boys (OR, 4.4; 95% CI, 1.5 to 13.6; vs OR, 1.2; 95% CI, 0.4 to 3.6), while that of sore throats and HS was higher in girls (OR, 52.7; 95% CI, 6.0 to 460.2; vs OR, 13.3; 95% CI, 3.0 to 58.5). At follow-up, 39 of 80 eligible habitual snorers (48.8%) still snored regularly. Children who continued to snore differed significantly in maternal education, household smoking, snoring loudness, and prior ear, nose, throat surgery from those who had ceased to snore habitually. CONCLUSIONS: Socioeconomic status, obesity, signs of nasal obstruction, and pharyngeal problems were independent risk factors for HS in these primary school children. The expression of HS varied considerably over time.

Snoring, intermittent hypoxia and academic performance in primary school children.

Sleep-disordered breathing is associated with impaired attention and neurocognitive deficits. We assessed the association of snoring and intermittent hypoxia with poor academic performance in third grade school children (1,144 children). Snoring frequency and intermittent hypoxia were investigated using parental questionnaire and nocturnal home pulse oximetry. Intermittent hypoxia was specified as desaturation events of 90% or less pulse oximeter saturation. Poor academic performance was defined as grade 4-6 on a six-point scale (i.e., approximately the lowest quintile grades) in mathematics, science, reading, spelling, and/or handwriting in the most recent school report. Snoring "always" was significantly associated with poor academic performance in mathematics (odds ratio; 95% confidence interval: 3.6; 1.3-10.1), science (4.3; 1.3-14.6), and spelling (3.5; 1.2-10.3). Snoring "frequently" was also significantly associated with poor academic performance in mathematics (2.4; 1.3-4.7) and spelling (2.0; 1.04-3.8). A significant relationship between snoring and poor academic performance was also found in children without intermittent hypoxia, whereas intermittent hypoxia did not show an independent association with poor academic performance. Thus, habitual snoring (i.e., snoring frequently or always) was associated with poor academic performance in these primary school children.