Arousal and ventilatory responses to mild hypoxia in sleeping preterm infants

A failure to adequately respond to hypoxia has been implicated in the Sudden Infant Death Syndrome (SIDS). Preterm infants are at increased risk for SIDS, thus we compared ventilatory and arousal responses to mild hypoxia [15% oxygen (O₂)] in preterm and term infants. Eight preterm and 15 term infants were serially studied with daytime polysomnography during which nasal airflow was monitored by pneumotachograph at 2–5 weeks, 2–3 and 5–6 months. At each age, in both groups, hypoxia induced a significant decrease in oxygen saturation (SpO₂) during both active sleep (AS) and quiet sleep (QS). Infants invariably aroused in AS; and in QS either aroused or failed to arouse. In preterm infants arousal latency in AS was longer than in term infants ( P  < 0.05) at 2–5 weeks. Compared with term infants, preterm infants reached significantly lower SpO₂ levels at 2–5 weeks in both AS and QS non-arousing tests and at 2–3 months in QS. A biphasic hypoxic ventilatory response was observed in QS non-arousing tests in both groups of infants at all three ages. We conclude that the greater desaturation during a hypoxic challenge combined with the longer arousal latency in preterm infants could contribute to greater risk for SIDS.     

Time course of continuous positive airway pressure effects on central sleep apnoea in patients with chronic heart failure

Continuous positive airway pressure (CPAP) causes a variable immediate reduction in the frequency of central apnoeas and hypopnoeas in patients with congestive heart failure (CHF) and central sleep apnoea (CSA), but has beneficial mid-term effects on factors known to destabilize the ventilatory control system. We, therefore, tested whether CPAP therapy leads, in addition to its short-term effects on CSA, to a significant further alleviation of CSA after 12 weeks of treatment on the same CPAP level in such patients. CPAP therapy was initiated in 10 CHF patients with CSA. During the first night on CPAP, the pressure was stepwise increased to a target pressure of 8–12 cmH₂O or the highest level the patients tolerated (<12 cmH₂O). Throughout the second night (baseline CPAP), the achieved CPAP of the first night was applied. After 12 weeks of CPAP treatment, we performed a follow-up polysomnography (12 weeks CPAP) on the same CPAP level (8.6 ± 1.1 cmH₂0). We found a significant reduction of the apnoea-hypopnoea index (AHI) between the diagnostic polysomnography and baseline CPAP night (41.8 ± 19.2 versus 22.2 ± 12.6 events per hour; P  = 0.005). The AHI further significantly decreased between the baseline CPAP night and the 12 weeks CPAP night on the same CPAP level (22.2 ± 12.6 versus 12.8 ± 11.0 events per hour; P  = 0.028). We conclude that, in addition to its immediate effects, CPAP therapy leads to a time-dependent alleviation of CSA in some CHF patients, indicating that in such patients neither clinical nor scientific decisions should be based on a short-term trial of CPAP.     

Development of respiratory control instability in heart failure: a novel approach to dissect the pathophysiological mechanisms

Observational data suggest that periodic breathing is more common in subjects with low   F _ETCO2  , high apnoeic thresholds or high chemoreflex sensitivity. It is, however, difficult to determine the individual effect of each variable because they are intrinsically related. To distinguish the effect of isolated changes in chemoreflex sensitivity, mean   F _ETCO2  and apnoeic threshold, we employed a modelling approach to break their obligatory in vivo interrelationship. We found that a change in mean CO₂ fraction from 0.035 to 0.045 increased loop gain by 70 ± 0.083% ( P < 0.0001), irrespective of chemoreflex gain or apnoea threshold. A 100% increase in the chemoreflex gain (from 800 l min⁻¹ (fraction CO₂)⁻¹) resulted in an increase in loop gain of 275 ± 6% ( P < 0.0001) across a wide range of values of steady state CO₂ and apnoea thresholds. Increasing the apnoea threshold   F _ETCO2  from 0.02 to 0.03 had no effect on system stability. Therefore, of the three variables the only two destabilizing factors were high gain and high mean CO₂; the apnoea threshold did not independently influence system stability. Although our results support the idea that high chemoreflex gain destabilizes ventilatory control, there are two additional potentially controversial findings. First, it is high (rather than low) mean CO₂ that favours instability. Second, high apnoea threshold itself does not create instability. Clinically the apnoea threshold appears important only because of its associations with the true determinants of stability: chemoreflex gain and mean CO₂.     

Growth of Filipino infants who differ in body proportions at birth

Growth of infants who differ in body proportions at birth was followed during the first 12 months of life. The sample of 2,695 infants from Metropolitan Cebu, in the Central Philippines, was divided into five groups based on a cross tabulation of low-birth-weight(LBW) status (2,500 g or less) with low (<10th percentile), adequate (10th–90th percentile) or high (>90th percentile)Rohre's Index (RI). The groups exhibited significant differences in growth patterns. The importance of these groups, which reflect weight and body proportions of the infant at birth as a determinant of attained size at 2, 6, and 12 months of age, was evaluated by using multivariate techniques which took into consideration other factors known to affect growth. Results show that intergroup differences in growth patterns and attained size occur because of (1) differences in postnatal growth potential represented by weight and body proportions at birth, (2) differences in the important biological inputs that affect postnatal growth (such as feeding practices and morbidity), and (3) differences in the effects of inputs on growth. Infants who are LBW but well proportioned are most likely to remain small during the first year of life, while those with a low RI at birth are more capable of catch-up growth.     

Trends in quinolone susceptibility of Enterobacteriaceae among inpatients of a large university hospital: 1992–98

Objectives   To assess trends in quinolone susceptibility of Enterobacteriaceae isolated in a large university hospital.
Methods   Between 1992 and 1998, bacterial isolates were collected each year during a 3-month period to evaluate annual changes in susceptibility. In addition, the activities of fluoroquinolones (pefloxacin, norfloxacin, ofloxacin, ciprofloxacin) against nalidixic acid-resistant strains were determined by disk diffusion and MIC methodologies during the first and last year of the study.
Results   The susceptibility of Enterobacteriaceae to nalidixic acid was unchanged between 1992 and 1998 (86% versus 85%). However, at the species level, the susceptibility rates to nalidixic acid decreased for Escherichia coli from 92% to 89%, and for Enterobacter cloacae from 87% to 82%. In contrast, there was a 10% increase in the nalidixic acid susceptibility rates for Klebsiella pneumoniae (74% versus 83%), which was thought to be due to the control of the spread of epidemic extended-spectrum β -lactamase (ESBL)-producing strains. The overall susceptibility of the Enterobacteriaceae to the fluoroquinolones remained high during the study period, greater than 90% in the case of ciprofloxacin. However, nalidixic acid-resistant Escherichia coli showed decreased susceptibility to ciprofloxacin between 1992 and 1998, as reflected by a decrease in median zone diameter (26 mm to 19 mm), an increase in MIC₅₀ (0.25 mg/L to 1 mg/L) and a shift in MIC distribution (unimodal in 1992 to bimodal in 1998). This has resulted in the reduced susceptibility of Escherichia coli to fluoroquinolones between 1992 and 1998 (pefloxacin, 95–90%; ciprofloxacin, 99–95%).
Conclusions   The susceptibility of Escherichia coli to quinolones has decreased, and the level of susceptibility of the resistant strains has increased over the 7-year study period.     

Correlation among urinary eosinophil protein X, leukotriene E4, and 11-dehydrothromboxane B2 in patients with spontaneous asthmatic attack

Various kinds of cells and their mediators are thought to be involved in the pathogenesis of bronchial asthma. However, changes in each mediator or relationship among mediators during an asthmatic attack have not been well documented. In this study, to clarify whether eosinophil protein X (EPX) is a marker which is distinct from leukotriene E₄ (LTE₄), or 11-dehydrothromboxane B₂ (11DTXB₂), we measured the urinary excretion of EPX, LTE₄, and 11DTXB₂ in 14 asthmatics who were admitted to the hospital with either an acute asthmatic attack or status asthmaticus. These patients included eight atopic and six non-atopic types of bronchial asthma, with a median age of 34.0 years. Urinary excretion of EPX was significantly high on admission with the asthmatic attack, and returned to control levels 175 [122 –384] μg/day when the patients were in the improved state (1036–317 μg/day, P  < 0.01). Similar findings were observed in LTE₄ (155–59 ng/day, P  < 0.01) and 11DTXB₂ (991–442 ng/day, P  < 0.01). No significant differences in values were observed between atopic and non-atopic types of asthma in all three substances. When the individual data during the attack state were analysed, a significant correlation was observed between changes (%) in urinary EPX and those in urinary LTE₄, but no such relationship was observed between changes (%) in urinary EPX and those in urinary 11DTXB₂. These results suggest that measuring urinary EPX levels may be a useful marker for the understanding and management of the disease.     

Procalcitonin kinetics in Legionella pneumophila pneumonia

Little is known about procalcitonin (PCT) levels in patients with community-acquired pneumonia (CAP) caused by Legionella pneumophila . The aim of the present study was to investigate this infection marker in patients admitted with L. pneumophila pneumonia in relation to conventional inflammatory parameters, severity of pneumonia upon admission and clinical outcome. Eighteen patients admitted with CAP caused by L. pneumophila serogroup 1 were retrospectively examined. PCT measurements were carried out during the first week of admission in addition to measurements of C-reactive protein (CRP), white blood cell (WBC) count and registration of severity of pneumonia upon admission (CURB-65 score). The mean PCT level upon admission in patients with L. pneumophila pneumonia was 13.5 ng/mL (range 0.3–55.7 ng/mL). Mean CRP level was 397 mg/L (range 167–595 mg/L) and mean WBC count 11.7 × 10⁹/L (range 4.5–20.4 × 10⁹/L). Initial high PCT levels were indicative of more severe disease as reflected by prolonged intensive care unit (ICU) stay and/or in-hospital death. Patients admitted to the ICU showed significantly higher PCT levels compared with the remaining patients [26.7 ng/mL (range 4.6–55.7 ng/mL) vs. 6.9 ng/mL (range 0.3–29.3 ng/mL); p 0.019]. There was a significant correlation between Acute Physiology and Chronic Health Evaluation-II scores upon ICU admission and initial PCT levels upon hospital admission ( r  = 0.86; p 0.027). Persistently increased PCT levels during treatment were indicative of unfavourable clinical outcome. Conventional inflammatory parameters (CRP and WBC) and the CURB-65 score lacked this discriminatory capacity in our study population. PCT may therefore be a valuable tool in the initial clinical assessment and follow-up of patients with L. pneumophila pneumonia.     

Filaggrin mutations in the onset of eczema, sensitization, asthma, hay fever and the interaction with cat exposure

Background:  Filaggrin gene ( FLG ) mutations contribute to the development of eczema and asthma, but their contribution to sensitization and hay fever remains unclear.
Methods:  FLG mutations R501X, 2282del4 and R2447X were genotyped in the Prevention and Incidence of Asthma and Mite Allergy birth cohort ( n  = 934) to evaluate longitudinally, for up to 8 years, their association with eczema, sensitization, asthma, hay fever and their interaction with cat exposure.
Results:  The combined FLG mutations were significantly associated with eczema at all ages when occurring in the first year of life (OR = 2.0; 95% CI: 1.4–2.8). Combined FLG mutations were associated with both atopic and nonatopic eczema, as well as asthma (OR = 3.7; 95% CI: 1.8–7.5). When the FLG 2282del4 mutation was analysed separately, it was significantly associated with the development of eczema during the first year, having eczema up to 8 years and sensitization at the age of 8 years, which was enhanced by early-life cat exposure (ORs being 8.2; 95% CI: 2.6–25.9, 6.0; 95% CI: 3.2–11.3 and 5.4; 95% CI: 1.2–23.6 respectively). FLG 2282del4 was significantly associated with hay fever from the age 5 years onwards (OR = 3.9; 95% CI: 1.5–10.5).
Conclusions:  FLG mutations are associated both with atopic and nonatopic eczema starting in the first year of life. FLG mutations combined with eczema in the first year of life are associated with a later development of asthma and hay fever, a clear example of the atopic march. We confirm that cat exposure enhances the effect of a FLG mutation on the development of eczema and sensitization.     

Confirmation of the novel association at the BTNL2 locus with ulcerative colitis

Linkage in families and association in population case–control investigations have clearly shown that genes within the major histocompatibility complex region on chromosome 6p are relevant to the susceptibility and pathogenesis of ulcerative colitis (UC) and Crohn's disease. However, identifying the causative variants by fine mapping has not been conclusive. In this study using 58 single nucleotide polymorphisms (SNPs) with 616 UC cases, there was significant association with SNP rs2294881 of the (butyrophilin-like 2) BTNL2 gene with odds ratio (OR) = 2.80, confidence interval (CI) = 1.62–4.84 and P  = 5.69 × 10⁻⁴ ( P _Bonferroni = 3.3 × 10⁻²) and replication of SNP rs9268480. The missense SNP rs2076523 (K196E) showed novel association with a subset of UC cases with colectomy ( n  = 126), OR = 0.25, CI = 0.11–0.58 and P  = 4.42 × 10⁻⁴ ( P _Bonferroni = 2.56 × 10⁻²). These three associated variants within the BTNL2 gene were neither in linkage disequilibrium with each other nor correlated with the SNPs tagging the human leukocyte antigen (HLA)-DRB1*1502 and HLA-DRB1*0301 alleles.     

Interferon gamma receptor 1 gene polymorphism in patients with tuberculosis in China

The aim of the study was to examine the influence of the CA microsatellite polymorphisms of interferon gamma receptor 1 on patients with tuberculosis (TB) in the south-eastern Chinese population. Genomic DNA from patients with TB ( n  = 155) and ethnically matched controls ( n  = 89) were genotyped by short tandem repeat-PCR method. The allele frequency of (CA)₂₅ was 1.70-fold higher among patients than that among controls (95% CI 1.07–2.70) ( P  = 0.025). Compared with the non-(CA)₂₅/non-(CA)₂₅ reference group, the risk to TB of the carriers of (CA)₂₅/(CA)₂₅ genotypes were 6.46-fold (95% CI 1.40–29.74) ( P  = 0.0017) higher. On the contrary, the allele frequency of (CA)₂₆ was 0.29-fold lower in patients than that in controls (95% CI 0.11–0.76) ( P  = 0.012). Genotypes with (CA)₂₆ allele were at 0.35-fold (95% CI 0.13–0.98) ( P  = 0.045) lower to the risk of TB, compared with that of the non-(CA)₂₆/non-(CA)₂₆ in the reference group. The above results indicated that the allele (CA)₂₅ appeared to be susceptible to TB, while the allele (CA)₂₆ to be protective towards TB. Our data also suggest that the CA repeat was a highly polymorphic marker and could be used for linkage and association analysis.     

Dual involvement of coenzyme Q10 in redox signaling and inhibition of death signaling in the rat heart mitochondria

Coenzyme Q10 (CoQ) has long been utilized as a cardioprotective agent in various heart diseases. One of the most important mechanisms by which CoQ exerts cardioprotection is aerobic ATP production as a mobile electron carrier in the mitochondrial electron transfer chain. The ability of CoQ to afford myocardial protection is also attributed to its antioxidant property. However, CoQ may also act as a pro-oxidant through the generation of reactive oxygen species. Although excess oxidative stress is known to induce death signaling via cytochrome c release from mitochondria, it is now apparent that a brief exposure to oxidative stress stimulates redox signaling for acquisition of tolerance to oxidative stress. Therefore, we have investigated dual involvement of CoQ in redox signaling generation through enhanced production of reactive oxygen species and death signaling inhibition through antioxidation. Mitochondria were isolated from the rat heart and incubated with CoQ (10 or 100 microM) or its vehicle HCO 60 for 1 h. H2O2 and cytochrome c release from respiring mitochondria were increased by antimycin A (2 microM), an inhibitor of complex III respiratory chain, or by high Ca2+ (10 microM). This enhanced release of H2O2 was associated with an increase in lipid peroxidation as measured with 4-hydroxy-2-nonenal-modified proteins and with large amplitude swelling of mitochondria. CoQ potentiated H2O2 release from antimycin A- or high Ca(2+)-treated mitochondria, but was capable of inhibiting lipid peroxidation and large amplitude swelling, and attenuated cytochrome c release from the mitochondria. In addition, CoQ increased ATP synthesis by mitochondria. These results suggest that CoQ plays dual roles in mitochondrial generation of intracellular signaling. CoQ acts as a pro-oxidant that participates in redox signaling. CoQ also acts as an antioxidant that inhibits permeability transition and cytochrome c release, and increases ATP synthesis, thereby attenuating death signaling toward apoptosis and necrosis.     

Pressure stability of nasal CPAP and bilevel devices

Summary Question of the study   Nasal continuous positive airway pressure (CPAP) prevents collapse of the upper airway during sleep in patients with obstructive sleep apnea provided that a positive transmural pressure can be maintained during inspiration. We examined pressure-flow characteristics in seven CPAP and bilevel devices during spontaneous breathing.
Methods   The CPAP devices were set to a pressure level of 9.8  hPa (10  cm H₂O) and adapted to a pneumotachograph using a standard CPAP hose and an outlet valve. We continuously measured flow, volume and pressure during resting ventilation and increasing voluntary hyperventilation and analysed the dependence of the variables on a breath-to-breath basis.
Results   Mean CPAP pressures differed between the devices (9.9 – 10.6  hPa) despite the same settings. In all machines pressure fell during inspiration to 8.4 – 9.8  hPa and increased during expiration to 11.1 – 11.7  hPa. This effect increased with higher flow rates. Maximum expiratory pressures rose to 12 – 19  hPa at peak flow rates of 2 l/s, mean expiratory pressures to 9.5 – 16  hPa. Inspiratory pressures dropped to 8.5 – 4.5  hPa (minimum) and 10.5 – 6.0 (mean). Bilevel devices showed a higher stability than CPAP devices. Pressure swings during the respiratory cycle increased the additional work of breathing.
Conclusions   Due to differences in mean and effective CPAP levels CPAP devices are not simply exchangeable but should be individually adapted. Patients with higher minute ventilation might benefit from more stable CPAP machines. The impact on patients' compliance remains to be evaluated.     

Lack of control of severe asthma is associated with co-existence of moderate-to-severe rhinitis

Background:  Retrospective studies provide evidence that rhinitis is associated with more severe asthma. The aim of this study was to evaluate prospectively whether rhinitis is a predictor of increased asthma severity.
Methods:  Five hundred and fifty-seven patients with severe asthma were enrolled. During 1 year of follow-up, each patient was evaluated every 3 months with a record of emergency room visits and supply of topical corticosteroids for asthma and rhinitis. In the 1 year of follow-up visit, the patients were checked for rhinitis diagnosis, severity and answered questionnaires for asthma symptoms and quality of life.
Results:  Eighty-two (15%) patients had no rhinitis, 299 (54%) had mild rhinitis and 176 (31%) moderate/severe rhinitis. In logistic regression models, moderate/severe rhinitis was a predictor for any emergency room visit in the follow-up period [3.83 (2.00–7.35)], for the presence of uncontrolled asthma after 1 year of follow-up [12.68 (1.73–92.85)], for <10% improvement of the airway obstruction [2.94 (1.48–5.85)] and <50% reduction in the number of emergency room visits [2.90 (1.02–8.26)] in the year of follow-up. It was also associated with a smaller chance of more than 90% reduction in the number of emergency room visits in the year of follow-up [0.27 (0.12–0.60)]. In a multivariate linear regression model, severity of rhinitis was positively correlated with a score of asthma severity and inversely correlated to an index of quality of life.
Conclusions:  In a population with severe asthma, moderate/severe rhinitis is a strong predictor for greater severity of asthma.     

Seasonal variation in Escherichia coli bloodstream infection: a population-based study

Seasonal variation in the rates of infection with certain Gram-negative organisms has been previously examined in tertiary-care centres. We performed a population-based investigation to evaluate the seasonal variation in Escherichia coli bloodstream infection (BSI). We identified 461 unique patients in Olmsted County, Minnesota, from 1 January 1998 to 31 December 2007, with E. coli BSI. Incidence rates (IR) and IR ratios were calculated using Rochester Epidemiology Project tools. Multivariable Poisson regression was used to examine the association between the IR of E. coli BSI and average temperature. The age- and gender-adjusted IR of E. coli BSI per 100 000 person-years was 50.2 (95% CI 42.9–57.5) during the warmest 4 months (June through September) compared with 37.1 (95% CI 32.7–41.5) during the remainder of the year, resulting in a 35% (95% CI 12–66%) increase in IR during the warmest 4 months. The average temperature was predictive of increasing IR of E. coli BSI (p 0.004); there was a 7% (95% CI 2–12%) increase in the IR for each 10-degree Fahrenheit ( c. 5.5°C) increase in average temperature. To our knowledge, this is the first study to demonstrate seasonal variation in E. coli BSI, with a higher IR during the warmest 4 months than during the remainder of the year.     

CTLA-4 +49A/G polymorphism is associated with Behçet's disease in a Tunisian population

The involvement of excessive T-helper cell functions in the pathogenesis of Behçet's disease (BD) has been reported. Cytotoxic T-lymphocyte antigen-4 (CTLA-4) plays a role in T-cell downregulation. In this report, we investigated the possible association between BD patients and the CTLA-4 +49A/G polymorphism in Tunisian population. A total of 135 Tunisian BD patients and 151 healthy blood donors from the same geographic area were genotyped by polymerase chain reaction for the CTLA-4 +49 A/G polymorphism. A highly significant difference between Tunisian BD patients and healthy controls was found regarding the distribution of CTLA-4 +49 A allele [ P  < 10⁻⁷; χ² = 75.63; odds ratio (OR) = 4.63; 95% confidence interval (CI) = 3.20–6.72] and genotype frequencies ( P  < 10⁻⁷; χ² = 71.02). Furthermore, in the BD group, the A allele was predominant in males (76.3%) when compared with females (62%), ( P  = 0.014; χ² = 5.97; OR = 1.99; 95% CI = 1.10–3.59). No relationship was found between the studied genotype and clinical manifestations. Our results show a gene dose effect of the A allele on the BD. The A allele exerts a stronger effect on disease susceptibility in males compared with females.     

Epicutaneous aeroallergen sensitization in atopic dermatitis infants - determining the role of epidermal barrier impairment

Background:  Sensitization to atopens is an early phenomenon that overlaps with the onset of atopic dermatitis (AD) in infancy. Early epidermal barrier impairment may facilitate the epicutaneous penetration of atopens.
Objective:  To correlate transepidermal water loss (TEWL) and aeroallergen sensitization in infants with AD.
Methods:  In this cross-sectional study we enrolled 59 AD children and 30 controls aged 3–12 months. Transepidermal water loss in uninvolved skin, specific immunoglobulin E, atopy patch test (APT) and skin prick tests were performed with respect to seven aeroallergens, i.e., Dermatophagoides pteronyssinus , D. farinae , cat, dog, birch pollen, ambrosia, and cockroach. Environmental conditions were assessed by a questionnaire, and the house dust mite (HDM) concentration was determined in dust samples.
Results:  Eighty-nine percent of AD infants had a positive APT vs one out of eleven controls. AD infants had a significantly higher mean TEWL than controls (27.4 vs 11.1 g/m²/h, P  < 0001). Children with two or more positive APT had higher TEWL than the others (31.1 vs 19.0 g/m²/h, P  < 0.025). No correlation was found between indoor APT results and exposure to HDM, cats, and dogs at home.
Conclusions:  This study confirms the high prevalence of delayed sensitization to indoor and outdoor aeroallergens in AD infants, and shows that the higher the TEWL, the higher the prevalence of sensitization to aeroallergens. These data are in favor of a major role of a constitutive epidermal barrier impairment in determining early atopen sensitization in infants with AD.     

A randomized prospective long-term study of two oral appliances for sleep apnoea treatment

Various types of mandibular protrusive appliances have revealed different treatment success in mild-to-moderate obstructive sleep apnoea (OSA). The present study compared the long-term effect of two different appliances in the treatment of OSA. A total of 103 patients with OSA were randomized and treated with an IST^® or Thornton Anterior Positioner (TAP^™) appliance. They were followed-up after a short-term treatment period of 6 months and long-term treatment period of over 24 months. Sleep studies in the sleep laboratory were conducted with and without the appliances, and various questionnaires assessing subjective daytime sleepiness, sleep quality, quality of life and symptom scores were administered at each time interval. Quality of life, sleep quality, sleepiness, symptoms and sleep outcome showed significant improvement in the short-term evaluation with both appliances, but the TAP^™ appliance revealed a significantly greater effect. After more than 2 years of treatment, sleep outcomes revealed an equal effect with both appliances. The subjective benefits achieved initially lessened significantly. This study illustrates that both the IST^® and the TAP^™ appliances are effective therapeutic devices for OSA after a period of over 24 months. Lack of compliance may be due to insufficient improvement in anticipated subjective symptoms and/or a recurrence of symptoms over time.     

Asthma, body mass, gender, and Hispanic national origin among 517 preschool children in New York City

Background:  Striking differences in asthma prevalence have been reported among Hispanic adults and children living in different cities of the USA. Prevalence is highest among those of Puerto Rican and lowest among those of Mexican origin. We hypothesized that body size would mediate this association.
Methods:  Parents of children in New York City Head Start programs completed a questionnaire including demographic factors, health history, a detailed history of respiratory conditions, lifestyle, and home environment. Children's height and weight were measured in home visits. Logistic regression was used to model the association of asthma with body mass index percentile (<85th percentile, gender/age specific vs ≥85th percentile, gender/age specific), national origin, and other factors.
Results:  Of 517 children at mean age of 4.0 ± 0.6 years, 34% met the study criteria for asthma, and 43% were above the 85th percentile. Asthma was strongly associated with non-Mexican national origin, male gender, allergy symptoms, and maternal asthma, and marginally with body size. The odds of asthma among boys of non-Mexican origin was 5.9 times that among boys of Mexican origin [95% confidence interval (CI): 2.9–12.2]; the comparable odds ratio (OR) among girls was 1.8 (95% CI: 0.9–3.6). Body mass was associated with asthma among girls [OR = 2.0 (95% CI: 1.1–3.7)], but not boys [OR = 1.4 (95% CI: 0.8–2.6)].
Conclusions:  The association of asthma with both body mass and national origin was gender-specific among the children in our study. Ours is one of the first studies to report on pediatric asthma in different Hispanic populations in the same city, by gender.     

Both allergic and nonallergic asthma are associated with increased FENO levels, but only in never-smokers

Background:  Allergic asthma is consistently associated with increased FE_NO levels whereas divergence exists regarding the use of exhaled nitric oxide (NO) as marker of inflammation in nonallergic asthma and in asthmatic smokers. The aim of this study is to analyze the effect of having allergic or nonallergic asthma on exhaled nitric oxide levels, with special regard to smoking history.
Methods:  Exhaled NO measurements were performed in 695 subjects from Turin (Italy), Gothenburg and Uppsala (both Sweden). Current asthma was defined as self-reported physician-diagnosed asthma with at least one asthma symptom or attack recorded during the last year. Allergic status was defined by using measurements of specific immunoglobulin E (IgE). Smoking history was questionnaire-assessed.
Results:  Allergic asthma was associated with 91 (60, 128) % [mean (95% CI)] increase of FE_NO while no significant association was found for nonallergic asthma [6 (–17, 35) %] in univariate analysis, when compared to nonatopic healthy subjects. In a multivariate analysis for never-smokers, subjects with allergic asthma had 77 (27, 145) % higher FE_NO levels than atopic healthy subjects while subjects with nonallergic asthma had 97 (46, 166) % higher FE_NO levels than nonatopic healthy subjects. No significant asthma-related FE_NO increases were noted for ex- and current smokers in multivariate analysis.
Conclusions:  Both allergic and nonallergic asthma are related to increased FE_NO levels, but only in never-smoking subjects. The limited value of FE_NO to detect subjects with asthma among ex- and current smokers suggests the predominance of a noneosinophilic inflammatory phenotype of asthma among ever-smokers.     

Heart rate increment analysis is not effective for sleep-disordered breathing screening in patients with chronic heart failure

Frequency domain analysis of heart rate variation has been suggested as an effective screening tool for sleep-disordered breathing (SDB) in the general population. The aim of this study was to assess this method in patients with chronic congestive heart failure (CHF). We included prospectively 84 patients with stable CHF, left ventricular ejection fraction (LVEF) <45% and sinus rhythm. The patients underwent polygraphy to measure the apnoea/hypopnoea index (AHI) and simultaneous Holter electrocardiogram monitoring to measure the power spectral density of the very low frequency component of the heart rate increment, expressed as the percentage of total power spectral density [% very low frequency increment (%VLFI)]. %VLFI could be determined in 54 patients (mean age, 52.8 ± 12.3 years; LVEF, 33.5 ± 9.8%). SDB defined as AHI ≥15 h⁻¹ was diagnosed in 57.4% of patients. Percent VLFI was not correlated with AHI ( r  =   0.12). Receiver-operating characteristic curves constructed using various AHI cut-offs (5–30 h⁻¹) failed to identify a %VLFI cut-off associated with SDB. The 2.4% VLFI cut-off recommended for the general population of patients with suspected SDB had low specificity (35%) and low positive and negative predictive values (35% and 54%, respectively). Heart rate increment analysis has several limitations in CHF patients and cannot be recommended as an SDB screening tool in the CHF population.