Gender Differences in Asthma Development and Progression

Antioxidant defense enzyme genes and asthma susceptibility: gender-specific effects and heterogeneity in gene-gene interactions between pathogenetic variants of the disease

Oxidative stress resulting from an increased amount of reactive oxygen species and an imbalance between oxidants and antioxidants plays an important role in the pathogenesis of asthma. The present study tested the hypothesis that genetic susceptibility to allergic and nonallergic variants of asthma is determined by complex interactions between genes encoding antioxidant defense enzymes (ADE). We carried out a comprehensive analysis of the associations between adult asthma and 46 single nucleotide polymorphisms of 34 ADE genes and 12 other candidate genes of asthma in Russian population using set association analysis and multifactor dimensionality reduction approaches. We found for the first time epistatic interactions between ADE genes underlying asthma susceptibility and the genetic heterogeneity between allergic and nonallergic variants of the disease. We identified GSR (glutathione reductase) and PON2 (paraoxonase 2) as novel candidate genes for asthma susceptibility. We observed gender-specific effects of ADE genes on the risk of asthma. The results of the study demonstrate complexity and diversity of interactions between genes involved in oxidative stress underlying susceptibility to allergic and nonallergic asthma.

Asthma incidence and risk factors in a national longitudinal sample of adolescent Canadians: a prospective cohort study

BACKGROUND

Estimates of asthma incidence and its possible determinants in adolescent populations have rarely been obtained using prospective designs. We sought to identify socio-demographic and other patterns in the incidence of asthma among Canadian adolescents and to examine possible behavioural and environmental determinants of asthma incidence using longitudinal analyses.

METHODS

We used data from the National Population Health Survey (NPHS), a nationally representative longitudinal survey of Canadians. All persons aged 12-18 years without asthma at baseline were followed up to a maximum of 12 years. The outcome was a reported diagnosis of asthma during the follow-up period. Analyses were weighted to the population and bootstrapping procedures were used to estimate variances.

RESULTS

Participants (n = 956) represented 2,038,890 adolescents of whom 293,450 (14.4%) developed asthma over the 21,274,890 person-years of follow-up. Overall, the incidence of asthma was 10.2 per 1000 person-years. In adjusted Cox regression analysis, being female (HR = 2.13, 95% CI = 1.26-3.62, p = 0.005) and being exposed to passive smoking (HR = 2.06, 95% CI = 1.27-3.34, p = 0.003) were associated with the development of asthma while no statistically significant associations were identified for rural residence, being overweight, and other health behaviours. There was also an apparent cohort effect among girls where girls who were older at baseline reported being diagnosed with asthma more over the follow-up than their younger counterparts. This was not observed among males.

CONCLUSIONS

Asthma prevention initiatives for adolescents should target girls and focus on smoking exposures. The role that differential diagnostic patterns play in these observations should be investigated to more accurately assess the incidence of asthma.

The relationship between body mass index, aerobic performance and asthma in a pre-pubertal, population-level cohort

PURPOSE

To assess the relationship between asthma, body mass index (BMI) and aerobic performance, as indicated by a shuttle test.

METHODS

20,577 participants (10,413 boys) from the SportsLinx serial cross-sectional study participated. Parental reports of asthma status and home postcode data were gathered from consent forms. Stature, sitting stature and body mass were measured and BMI, somatic maturity and indices of multiple deprivation scores (IMD) were derived. Performance on the 20 m multi-stage shuttle runs test (20mSRT) was used to estimate cardiorespiratory fitness (CRF).

RESULTS

Asthma [F (1, 17,015) = 82.26, P < 0.01] and gender [F (1, 17,015) = 678.491, P < 0.001] significantly influenced 20mSRT. The addition of BMI, maturity and IMD to the model did not alter these significant effects. There was a significant interaction between 20mSRT and BMI [F (1, 16,723) = 132.80, P < 0.01], with a significant decrease in 20mSRT from the 50th BMI percentile upwards [t (16,699) = 36.88, P < 0.01]. Binary logistic regression revealed gender and 20mSRT to be significant predictors of asthma occurrence; BMI SDS just reached significance whilst maturity and IMD were not significant contributors to the model.

CONCLUSIONS

This study demonstrates the negative influences of low CRF and high BMI on the risk of asthma occurrence in pre-pubertal children. Furthermore, it highlights the significant influence of BMI on CRF, revealing these effects to be manifest considerably below those BMI percentiles conventionally associated with being overweight or obese.

Asthma prevalence and risk factors among children and adolescents living around an industrial area: a cross-sectional study

Background

The exposure to air pollution has negative effects on human health, increasing the risk of respiratory diseases, such as asthma. Few data are yet available on the epidemiology of childhood asthma in some areas of Italy. The aim of the study was to estimate asthma prevalence and related risk factors in children and adolescents residents around the industrial area of Termoli, Molise region, Central-South Italy.

Methods

Prevalence was assessed through the administration of modified ISAAC questionnaires filled out by parents of 89 children and adolescents for the identification of confirmed and probable cases, and by analyzing pediatricians’ databases on drug prescriptions for symptoms control and treatment of assisted population in the study area (n = 1,004), compared to a control area (n = 920) with lower industrialization. The association of asthma with risk factors was evaluated by univariate (Chi-square or Fisher’s Exact test) and regression logistic analysis.

Results

A total of 22 (24.7%) asthmatics were identified, including both confirmed (n = 7; 7.9%) and probable cases (n = 15; 16.8%), most of them (n = 17; 77.3%) resident of Termoli town. All asthma cases were georeferenced based on the residence, however clusters were not found. Using drug prescriptions analysis, a higher prevalence (n = 138; 13.7%) of diagnosed cases was found. Lifetime history of both atopic dermatitis and bronchitis were significantly relateds to asthma cases, as well as an elevated body mass index, whose association is consistent with prevalence data of overweight/obese children living in the study area. Moreover, being resident of the town of Termoli was associated to the occurrence of cases.

Conclusions

Although our data indicated a prevalence concordance with previous national studies in pediatric population, a definitive correlation with environmental industrial factors present in the study area was not established. However, asthma outcome was significantly associated to individuals living in the town of Termoli that, despite the industrial/manufacturing activities, is also subjected to a higher environmental pressure due to the presence of toll road, state highway, railroad, and seaport which may cause air pollution from motor vehicle traffic and increase asthma induction. This study provides hitherto unavailable data on asthma in childhood population living in an industrialized area which was never investigated before, could be part of a systematic review or meta-analysis procedure, might suggest significant findings for larger observational studies, and contribute to complete the frame of disease epidemiology in Italy.

Nongenomic bronchodilating action elicited by dehydroepiandrosterone (DHEA) in a guinea pig asthma model

Primates secrete large amounts of the precursor steroid dehydroepiandrosterone (DHEA); in humans, its levels are low during childhood and start declining after the fourth decade. It has been postulated that the progressive decline in DHEA levels may be related with the severity of asthma associated with age. To determine whether DHEA may regulate the airway smooth muscle (ASM) activity, isolated tracheal rings with and without epithelium from male guinea pigs were isometrically recorded to characterize the response of ASM to DHEA at different concentrations on KCl- and carbachol (CCh)-induced contraction as well as on ovalbumin (OVA)-induced contraction in sensitized guinea pigs. Additionally, we used barometric plethysmography in sensitized guinea pigs in order to compare changes of the lung resistance increased by the antigen challenge to OVA in the absence and presence of different doses of DHEA. DHEA concentration-dependently abolished the contraction to KCl, CCh and OVA, and no differences were found in preparations with and without epithelium. DHEA-induced relaxation was not modified by the suppression of protein synthesis or transcription, pharmacological inhibition of nitric oxide (NO) synthase, nor by antagonist of β2-adrenergic receptors or an inhibitor of the 3β-HSD enzyme. Likewise, Ca(2+)-induced contraction in Ca(2+)-free depolarized tissues was antagonized by DHEA, and the contraction to the L-type voltage-dependent calcium channel activator (Bay K 8644) was inhibited by DHEA. Furthermore, DHEA prevented OVA-induced increases in lung resistance. These results indicate that DHEA-induced relaxation in ASM is a nongenomic (membrane) action and is not produced after its bioconversion. The data suggest that DHEA-induced relaxation is an epithelium- and NO-independent mechanism that involves a blockade of voltage-dependent calcium channels and possible non-selective cation channels.

Androgen receptor function links human sexual dimorphism to DNA methylation

Sex differences are well known to be determinants of development, health and disease. Epigenetic mechanisms are also known to differ between men and women through X-inactivation in females. We hypothesized that epigenetic sex differences may also result from sex hormone functions, in particular from long-lasting androgen programming. We aimed at investigating whether inactivation of the androgen receptor, the key regulator of normal male sex development, is associated with differences of the patterns of DNA methylation marks in genital tissues. To this end, we performed large scale array-based analysis of gene methylation profiles on genomic DNA from labioscrotal skin fibroblasts of 8 males and 26 individuals with androgen insensitivity syndrome (AIS) due to inactivating androgen receptor gene mutations. By this approach we identified differential methylation of 167 CpG loci representing 162 unique human genes. These were significantly enriched for androgen target genes and low CpG content promoter genes. Additional 75 genes showed a significant increase of heterogeneity of methylation in AIS compared to a high homogeneity in normal male controls. Our data show that normal and aberrant androgen receptor function is associated with distinct patterns of DNA-methylation marks in genital tissues. These findings support the concept that transcription factor binding to the DNA has an impact on the shape of the DNA methylome. These data which derived from a rare human model suggest that androgen programming of methylation marks contributes to sexual dimorphism in the human which might have considerable impact on the manifestation of sex-associated phenotypes and diseases.

Epidemiologic methods of assessing asthma and wheezing episodes in longitudinal studies: measures of change and stability

Background

In settings in which diseases wax and wane, there is a need to measure disease dynamics in longitudinal studies. Traditional measures of disease occurrence (eg, cumulative incidence) do not address change or stability or are limited to stable cohorts (eg, incidence) and may thus lead to erroneous conclusions. To illustrate how different measures can be used to detect disease dynamics, we investigated sex differences in the occurrence of asthma and wheezing, using a population-based study cohort that covered the first 18 years of life.

Methods

In the Isle of Wight birth cohort (n = 1456), prevalence, incidence, cumulative incidence, positive and negative transitions, and remission were determined at ages 1 or 2, 4, 10, and 18 years. Latent transition analysis was used to simultaneously identify classes of asthma and wheezing (related phenotypes) and characterize transition probabilities over time. Trajectory analysis was used to characterize the natural history of asthma and wheezing.

Results

Regarding time-specific changes, positive and negative transition probabilities were more informative than other measures of associations because they revealed a sex switchover in asthma prevalence (P < 0.05). Transition probabilities were able to identify the origin of a sex-specific dynamic; in particular, prior wheezing transitioned to asthma at age 18 years among girls but not among boys. In comparison with latent transition analysis, trajectory analysis did not directly identify a switchover in prevalence among boys and girls.

Conclusions

In longitudinal analyses, transition analyses that impose minimal restrictions on data are needed in order to produce appropriate information on disease dynamics.

The association between hospitalization for asthma in childhood and alcohol use disorder hospitalization during adolescence and early adulthood among males in an Australian birth cohort

OBJECTIVE

Associations between asthma and a range of mental disorders have been increasingly reported from cross-sectional studies. The aim of this study is to investigate whether hospitalization for asthma during childhood is associated with an increased risk of hospitalization for alcohol use disorders during adolescence and early adulthood.

METHOD

This study used a population-based birth-cohort design and included males (n = 56369) born between 1980 and 1984 in Western Australia (WA). Hospitalizations for asthma and alcohol use disorders were identified using ICD-9 codes and ICD-10 codes. Survival analysis and multivariate Poisson regression model were used in the analysis.

RESULTS

The risk of alcohol use disorder hospitalization was significantly higher among participants who had been hospitalized for asthma during ages 3-6 years and 12-18 years.

CONCLUSION

In this cohort study of Western Australian males, hospitalizations for asthma during childhood were associated with an increased risk of alcohol use disorder hospitalization among males.

Asthma Heredity, Cord Blood IgE and Asthma-Related Symptoms and Medication in Adulthood: A Long-Term Follow-Up in a Swedish Birth Cohort

Cord blood IgE has previously been studied as a possible predictor of asthma and allergic diseases. Results from different studies have been contradictory, and most have focused on high-risk infants and early infancy. Few studies have followed their study population into adulthood. This study assessed whether cord blood IgE levels and a family history of asthma were associated with, and could predict, asthma medication and allergy-related respiratory symptoms in adults. A follow-up was carried out in a Swedish birth cohort comprising 1,701 consecutively born children. In all, 1,661 individuals could be linked to the Swedish Prescribed Drug Register and the Medical Birth Register, and 1,227 responded to a postal questionnaire. Cord blood IgE and family history of asthma were correlated with reported respiratory symptoms and dispensed asthma medication at 32-34 years. Elevated cord blood IgE was associated with a two- to threefold increased risk of pollen-induced respiratory symptoms and dispensed anti-inflammatory asthma medication. Similarly, a family history of asthma was associated with an increased risk of pollen-induced respiratory symptoms and anti-inflammatory medication. However, only 8% of the individuals with elevated cord blood IgE or a family history of asthma in infancy could be linked to current dispensation of anti-inflammatory asthma medication at follow-up. In all, 49 out of 60 individuals with dispensed anti-inflammatory asthma medication at 32-34 years of age had not been reported having asthma at previous check-ups of the cohort during childhood. Among those, only 5% with elevated cord blood IgE and 6% with a family history of asthma in infancy could be linked to current dispensation of anti-inflammatory asthma medication as adults. Elevated cord blood IgE and a positive family history of asthma were associated with reported respiratory symptoms and dispensed asthma medication in adulthood, but their predictive power was poor in this long-time follow-up.

Prevalence and risk factors of asthma in off-reserve Aboriginal children and adults in Canada

Only a few studies have investigated asthma morbidity in Canadian Aboriginal children. In the present study, data from the 2006 Aboriginal Peoples Survey were used to determine the prevalence and risk factors for asthma in Canadian Aboriginal children six to 14 years of age and adults 15 to 64 years of age living off reserve. The prevalence of asthma was 14.3% in children and 14.0% in adults. Children and adults with Inuit ancestry had a significantly lower prevalence of asthma than those with North American Indian and Métis ancestries. Factors significantly associated with ever asthma in children included male sex, allergy, low birth weight, obesity, poor dwelling conditions and urban residence. In adults, factors associated with ever asthma varied among Aboriginal groups; however, age group, sex and urban residence were associated with ever asthma in all four Aboriginal groups. The prevalence of asthma was lower in Aboriginal children and higher in Aboriginal adults compared with that reported for the Canadian population. Variation in the prevalence of and risk factors for asthma among Aboriginal ancestry groups may be related to genetic and environmental factors that require further investigation.

Association of breastfeeding with asthma in young Aboriginal children in Canada

BACKGROUND

Few studies have investigated the factors associated with asthma in young Aboriginal children.

OBJECTIVE

To characterize the association of demographic, environmental and early life factors with asthma in young Aboriginal children in Canada.

METHODS

The 2006 Aboriginal Children's Survey was conducted among off-reserve Aboriginal children zero to six years of age to obtain information on Aboriginal children's development and well-being. The prevalence of asthma in Aboriginal children was obtained from the parental report of asthma as diagnosed by a health care professional.

RESULTS

The prevalence of reported asthma among off-reserve Aboriginal children zero to six years of age (n=14,170) was 9.4%. Asthma prevalence in both exclusively breastfed children (6.8%) and ever but not exclusively breastfed children (9.0%) was significantly lower than that in nonbreastfed children (11.0%). In the multiple logistic regression analysis, exclusive breastfeeding was protective of asthma compared with nonbreastfeeding (OR 0.59 [95% CI 0.44 to 0.78]). Older age groups, male sex, having two or more older siblings, low birth weight, day care attendance and ear infection were significant risk factors for asthma.

CONCLUSIONS

The prevalence of asthma among young Aboriginal children zero to six years of age living off reserve was slightly lower than that reported for all other Canadian children. Breastfeeding, especially exclusively breastfeeding, was protective of asthma in Aboriginal children, which is consistent with what has been observed in non-Aboriginal children in Canada. Public health interventions intended for reducing asthma incidence in young Aboriginal children should include breastfeeding promotion programs.

Early life influences on the development of chronic obstructive pulmonary disease

There is increasing evidence that chronic obstructive pulmonary disease (COPD) is not simply a disease of old age that is largely restricted to heavy smokers, but may be associated with insults to the developing lung during foetal life and the first few years of postnatal life, when lung growth and development are rapid. A better understanding of the long-term effects of early life factors, such as intrauterine growth restriction, prenatal and postnatal exposure to tobacco smoke and other pollutants, preterm delivery and childhood respiratory illnesses, on the subsequent development of chronic respiratory disease is imperative if appropriate preventive and management strategies to reduce the burden of COPD are to be developed. The extent to which insults to the developing lung are associated with increased risk of COPD in later life depends on the underlying cause, timing and severity of such derangements. Suboptimal conditions in utero result in aberrations of lung development such that affected individuals are born with reduced lung function, which tends to remain diminished throughout life, thereby increasing the risk both of wheezing disorders during childhood and subsequent COPD in genetically susceptible individuals. If the current trend towards the ever-increasing incidence of COPD is to be reversed, it is essential to minimize risks to the developing lung by improvements in antenatal and neonatal care, and to reduce prenatal and postnatal exposures to environmental pollutants, including passive tobacco smoke. Furthermore, adult physicians need to recognize that lung disease is potentially associated with early life insults and provide better education regarding diet, exercise and avoidance of smoking to preserve precious reserves of lung function in susceptible adults. This review focuses on factors that adversely influence lung development in utero and during the first 5 years of life, thereby predisposing to subsequent COPD.

Offspring IgE responses are influenced by levels of maternal IgG transferred in early life

PROBLEM

Maternal immune responses may interfere with offspring allergy development as maternal immunization may suppress IgE development, while maternal allergy may promote allergy. Therefore, we investigated the effect of two different maternal treatments on airway allergy in female and male offspring.

METHOD OF STUDY

Pregnant mice were immunized (IMM) with ovalbumin (OVA) or immunized and airway-challenged (IMM+AI). At different ages, airway allergy to OVA was induced in offspring by intranasal sensitization.

RESULTS

Maternal IgG1 was found at higher levels in IMM+AI than in IMM offspring. After sensitization, the suppression of OVA-specific IgE and IgG1 was complete in juvenile offspring but waned with age concurrently with maternal IgG1 levels. Cytokine secretion, lung inflammation, and B cell priming were not suppressed although IgE responses were.

CONCLUSIONS

High compared with low levels of maternal IgG1 were associated with lower TH 2 antibody production after adult offspring were re-exposed to OVA. Thus, offspring allergy-related responses appeared to be shaped by maternal antibody levels.

Asthma and COPD in an Italian adult population: role of BMI considering the smoking habit

Smoking and body mass index (BMI) are well-documented risk factors that contribute substantially to chronic obstructive pulmonary disease (COPD) and asthma. However, the relations among smoking, obesity, and COPD or asthma remain to be clarified. We conducted a population-based cross-sectional epidemiologic study to explore the association between BMI and COPD or asthma among non-smokers, smokers and ex-smokers using information obtained from the Health Search database (HSD) owned by the Italian College of General Practitioners (SIMG), which stores information on about 1.5% of the total Italian population served by general practitioners (GPs). Our study confirms the importance of smoking status in patients with COPD, but not in those with asthma. Moreover, it demonstrates that the increase in BMI is frequently associated with the diagnosis of COPD or asthma, suggesting that the probability of suffering from COPD or asthma increases with the increase in body weight regardless of the smoking status. The association between an increase in BMI appears to be greater in women than in men. Our data also show that underweight is significantly associated with COPD, but only in men, while being underweight apparently protects from the possibility of suffering from asthma.

Relevance of birth cohorts to assessment of asthma persistence

The definition of persistent asthma in longitudinal studies reflects symptoms reported at every assessment with no substantive asymptomatic periods. Early-childhood wheezing may be transient, especially if it is of viral etiology. Longitudinal studies provide greater opportunity to confirm the diagnosis by variability of symptoms, objective measurements, and therapeutic responses. Several clinical phenotypes of childhood asthma have been identified, with general consistency between cohorts. Persistent wheezing is often associated with loss of lung function, which is evident from early-childhood and related to persistent inflammation and airway hyperresponsiveness. Female sex, atopy, airway responsiveness, and personal smoking, but not exposure to environmental tobacco smoke, are risk factors for persistence of childhood asthma into adulthood. The effect of breastfeeding remains controversial, but gene-environment interactions may partly explain outcomes. Understanding the natural history and underlying causes of asthma may lead to development of strategies for primary prevention.

Maternal microchimerism protects against the development of asthma

BACKGROUND

Maternal asthma and child's sex are among the most significant and reproducible risk factors for the development of asthma. Although the mechanisms for these effects are unknown, they likely involve nonclassical genetic mechanisms. One such mechanism could involve the transfer and persistence of maternal cells to her offspring, a common occurrence known as maternal microchimerism (MMc). MMc has been associated with many autoimmune diseases but has not been investigated for a role in asthma or allergic disease.

OBJECTIVE

We hypothesized that some of the observed risks for asthma may be due to different rates of transmission or persistence of maternal cells to children of mothers with asthma compared with children of mothers without asthma, or to sons compared with daughters. We further hypothesized that rates of MMc differ between children with and without asthma.

METHODS

We tested these hypotheses in 317 subjects from 3 independent cohorts by using a real-time quantitative PCR assay to detect a noninherited HLA allele in the child.

RESULTS

MMc was detected in 20.5% of the subjects (range 16.8%-27.1% in the 3 cohorts). We observed lower rates of asthma among MMc-positive subjects than among MMc-negative subjects (odds ratio, 0.38; 95% CI, 0.19-0.79; P = .029). Neither maternal asthma nor sex of the child was a significant predictor of MMc in the child (P = .81 and .15, respectively).

CONCLUSIONS

Our results suggest for the first time that MMc may protect against the development of asthma.

How robust is the evidence of an emerging or increasing female excess in physical morbidity between childhood and adolescence? Results of a systematic literature review and meta-analyses

For asthma and psychological morbidity, it is well established that higher prevalence among males in childhood is replaced by higher prevalence among females by adolescence. This review investigates whether there is evidence for a similar emerging female ‘excess’ in relation to a broad range of physical morbidity measures. Establishing whether this pattern is generalised or health outcome-specific will further understandings of the aetiology of gender differences in health. Databases (Medline; Embase; CINAHL; PsycINFO; ERIC) were searched for English language studies (published 1992–2010) presenting physical morbidity prevalence data for males and females, for at least two age-bands within the age-range 4–17 years. A three-stage screening process (initial sifting; detailed inspection; extraction of full papers), was followed by study quality appraisals. Of 11 245 identified studies, 41 met the inclusion criteria. Most (n = 31) presented self-report survey data (five longitudinal, 26 cross-sectional); 10 presented routinely collected data (GP/hospital statistics). Extracted data, supplemented by additional data obtained from authors of the included studies, were used to calculate odds ratios of a female excess, or female:male incident rate ratios as appropriate. To test whether these changed with age, the values were logged and regressed on age in random effects meta-regressions. These showed strongest evidence of an emerging/increasing female excess for self-reported measures of headache, abdominal pain, tiredness, migraine and self-assessed health. Type 1 diabetes and epilepsy, based on routinely collected data, did not show a significant emerging/increasing female excess. For most physical morbidity measures reviewed, the evidence broadly points towards an emerging/increasing female excess during the transition to adolescence, although results varied by morbidity measure and study design, and suggest that this may occur at a younger age than previously thought.

The effects of age and carbon black on airway resistance in mice

CONTEXT

Ambient particulate matter (PM) is associated with acute exacerbations of airflow obstruction. Additionally, elderly individuals are more susceptible to increased functional morbidity following acute PM exposure.

OBJECTIVE

The purpose of this study is to determine the aging effects of PM exposure on the responsiveness of airway smooth muscle in mice. We hypothesized that airway reactivity induced by methacholine (Mch) will increase with age in PM exposed mice.

MATERIALS AND METHODS

Male C57BL/6 (B6) mice at 11, 39, 67, and 96 weeks of age were exposed to carbon black (CB) or room air (RA) for 3 h on 3 consecutive days. One day after the last exposure, mice were anesthetized and airways resistance (R(aw)) was measured by forced oscillation following half-log dose increases of aerosolized Mch.

RESULTS

Baseline R(aw) was significantly lower in 67 and 96 week mice compared to 11-week mice (p < 0.05). In RA exposed mice, an age-dependent decline in Mch-induced airway reactivity occurred in association with the highest Mch doses at ages 67 and 96 weeks (p < 0.05). A significantly (p < 0.05) greater Mch-induced R(aw) response occurred in 67-week mice exposed to CB compared with age-matched RA-exposed mice.

DISCUSSION AND CONCLUSION

Our results show a progressive decrease in the Mch-induced R(aw) response with age in mice. The effect of CB exposure resulted in greater airway reactivity in middle-aged mice, which highlights the effects of PM exposure on the lung as it relates to increased morbidity and mortality with older age.

Sex Differences in the Effects of Inhaled Corticosteroids on Weight Gain among Patients with Asthma

Background. Studies have shown that asthma and asthma exacerbations are related to body weight and that this relationship might be sex-specific. While oral corticosteroids have been associated with weight gain, little is known about the effect of inhaled corticosteroid (ICS) use on short-term weight gain. The purpose of the present study was to examine whether ICSs would be associated with weight gain among asthmatic patients. Methods. A total of 180 adult patients with physician-diagnosed asthma provided details of their medical history and demographic information, along with height and weight at baseline and at one year. Weight change was defined as follow-up minus baseline weight. General linear models were used to assess the relationship between ICS dose (fluticasone propionate equivalent) and sex. Results. Significant main effects of sex (P=.005) and ICS dose (P=.036) and an interaction effect of sex and ICS dose (P=.003) on weight change were observed. Further analysis of the interaction indicated that women had greater weight gain, while men had decreased weight with increased ICS dose. Conclusions. Findings suggest that ICSs may trigger weight gain in females and highlight the need for studies to confirm this relationship and examine the potential underlying mechanisms.

Asthma and the menopause: a systematic review and meta-analysis

OBJECTIVE

To review the available literature to determine whether the menopausal transition is associated with asthma incidence.

METHODS

We performed a systematic review and meta-analysis of cohort and cross-sectional studies providing a definition/assessment of menopausal status, incidence or prevalence of a defined diagnosis of asthma, and providing a measure of the association or of menopausal state and asthma or enough data for a calculation of this association. Where possible these meta-analytic estimates were also stratified by intake of menopausal hormone therapy (MHT).

RESULTS

Of 76 potentially relevant articles, 8 studies met the inclusion criteria and were included in the review, and 6 in the meta-analysis. There was heterogeneity across studies: four studies reported slightly increased prevalence rates of asthma in post-menopause, one large cohort yielded a lower asthma incidence and one cross-sectional study a lower prevalence in post-menopause. Overall, the meta-analysis showed no significant association between menopause and asthma rates. When stratifying by use of MHT, the association between menopause and asthma rates was increased in women reporting use of MHT (RR 1.32, 95%CI 1.01-1.74), but not in women not using MHT.

CONCLUSION

We found no significant association of menopause with asthma prevalence or incidence except for women reporting use of MHT. However, these findings result from a small number of studies, including only 1 large cohort with incidence rates for pre- as well as post-menopause. Further studies are needed addressing more closely subgroup analyses and a possible modification of the association of menopause and asthma by MHT.

Relationships between total and allergen-specific serum IgE concentrations and lung function in young adults

BACKGROUND

Prior studies have shown relationships between serum immunoglobulin E (IgE) and asthma.

OBJECTIVE

To investigate relationships between total and allergen-specific IgE concentrations and lung function in young adults.

METHODS

Measurements of total IgE, allergen-specific IgE to 6 common allergens, and spirometry (forced expiratory volume in one second [FEV(1)], forced vital capacity [FVC], FEV(1)/FVC, and percent change in FEV(1) after bronchodilation) were used to calculate correlations between the logarithmically transformed IgE values and measures of lung function among participants in a birth cohort not selected for risk of allergic disease stratified by current asthma, prior asthma, or no asthma.

RESULTS

The 428 participants were 51.6% female, 93% white, and 18.4 (standard deviation = 0.6) years old. Forty-eight (11.2%) had current asthma, 55 (12.9%) had a history of asthma, and 325 (75.9%) never had asthma. For males with current asthma, correlations between total IgE and FEV(1)% and FVC% were -0.51 (P = .06) and -0.70 (P = .005), respectively. For females with current asthma, the only significant correlation was between total IgE and the FEV(1)/FVC ratio (-0.55, P = .001). After excluding smokers and individuals without detectable allergen-specific IgE, the negative correlations for both males and females remained statistically significant. The correlations among males or females with prior asthma or no history of asthma were minimal and not statistically significant. The sum of the allergen-specific IgEs showed the same pattern of relationships to lung function as did total IgE.

CONCLUSION

Our results show significant negative correlations that vary by gender between both total and allergen-specific IgE and measurements of lung function in young adults with current asthma.

Sex-specific differences in effect size estimates at established complex trait loci

BACKGROUND

Genetic differences between men and women may contribute to sex differences in prevalence and progression of many common complex diseases. Using the WTCCC GWAS, we analysed whether there are sex-specific differences in effect size estimates at 142 established loci for seven complex diseases: rheumatoid arthritis, type 1 diabetes (T1D), Crohn's disease, type 2 diabetes (T2D), hypertension, coronary artery disease and bipolar disorder.

METHODS

For each Single nucleotide polymorphism (SNP), we calculated the per-allele odds ratio for each sex and the relative odds ratios (RORs; the effect size is higher in men with ROR greater than one). RORs were then meta-analysed across loci within each disease and across diseases.

RESULTS

For each disease, summary RORs were not different from one, but there was between-SNP heterogeneity in the RORs for T1D and T2D. Four loci in T1D, three in Crohn's disease and three in T2D showed differences in the genetic effect between men and women (P<0.05). We probed these differences in additional independent replication samples for T1D and T2D. The differences remained for the T1D loci CTSH, 17q21 and 20p13 and the T2D locus BCL11A, when WTCCC data and replication data were meta-analysed. Only CTSH showed different genetic effect between men and women in the replication data alone.

CONCLUSION

Our results exclude the presence of large and frequent differences in the effect size estimates between men and women for the established loci in the seven common diseases explored. Documenting small differences in genetic effects between men and women requires large studies and systematic evaluation.

The association between leisure-time physical activities and asthma symptoms among 10- to 12-year-old children: the effect of living environment in the PANACEA study

OBJECTIVE

This study evaluated the interrelationships of living environment, physical activity, lifestyle/dietary habits, and nutritional status on the prevalence of childhood asthma.

METHODS

In a cross-sectional survey 1125 children (529 boys), 10 to 12 years old, were selected from 18 schools located in an urban environment (Athens, n = 700) and from 10 schools located in rural areas (n = 425) in Greece.

RESULTS

Children living in Athens had higher likelihood of "ever had" asthma compared with children living in rural areas (odds ratio (OR) = 1.78, 95% confidence interval (CI) = 1.25-2.54), after adjusting for age and sex. After adjusting for age, sex, body mass index, and adherence to the Mediterranean diet (KIDMED score), leisure-time physical activity was inversely associated with "ever had" asthma. When stratifying by county of residence, a trend toward reduced asthma symptoms among children engaged in outdoor physical activities during their leisure time who reside in rural (but not urban) environment was observed (OR = 0.88, 95% CI = 0.77-1.01).

CONCLUSIONS

The inverse relationship between asthma symptoms and leisure-time physical activity in the rural environment and the lack of an association between asthma symptoms and organized sports-related activities should draw the attention of public healthcare authorities. Their efforts should focus on the planning of a sustainable natural environment, which will promote the physical health of children and reduce the burden of childhood asthma.

Prevalence of respiratory symptoms at two time points in a population of children in Manchester--a cohort study

OBJECTIVE

Although the prevalence of asthma and atopy has been noted to have increased in recent decades, patterns of asthma prevalence have, traditionally, been difficult to track. Most reports on trends in childhood asthma have been cross-sectional measuring the prevalence in cohorts of similar aged children at different time points. The aim of this paper is to report on the prevalence of symptoms in the same cohort at two separate time points.

DESIGN

Retrospective cohort study.

SETTING

Community-based study, Central Manchester.

PARTICIPANTS

MANCAS1, study n=5086, participation n=2414. MANCAS2, study n=6338, participation n=1608. Children born in a hospital in Manchester within specified dates and still living or attending a school in Central Manchester were eligible for inclusion. Children on an 'at-risk' register or living with short-term carers were excluded.

OUTCOME MEASURES

Data on respiratory symptoms were collected at two separate time points using parent completed questionnaires.

RESULTS

Response rate for MANCAS1 was 47.5% and 25.4% for MANCAS2. There were 801 individuals for whom a response to both studies was received. There was a significant reduction in the prevalence of night cough (29.5% vs 18.3%, McNemar <0.01) and antibiotic use for respiratory infections (9.1% vs 4.3%, McNemar <0.01) between the two study time points. The prevalence of hay fever/eczema increased (41.6% vs 46.9%, McNemar <0.01) between the two studies. There was no significant difference in the prevalence of wheeze, exercise-induced wheeze or asthma medication.

CONCLUSIONS

Although this report of respiratory symptom prevalence in the same population at two time points over a 7-year period shows a constant burden of asthma symptoms, there is some suggestion of variability in asthma symptom prevalence within the cohort as the children matured while the burden of allergy symptoms increased.

Fatores associados ao controle da asma em pacientes pediátricos em centro de referência

OBJETIVO: Descrever os dados epidemiológicos, clínicos e os fatores associados ao controle da asma em pacientes asmáticos seguidos em um ambulatório pediátrico especializado. MÉTODOS: Estudo transversal de pacientes asmáticos ambulatoriais, para os quais eram fornecidas medicações profiláticas. A classificação da asma, as etapa de tratamento e a avaliação do controle seguiram a IV Diretrizes Brasileiras para o Manejo da Asma, de 2006. Os fatores avaliados foram: outras alergias, obesidade, imunodeficiências, refluxo gastresofágico e sensibilização alérgica, sendo comparados pacientes com asma controlada ou não com relação à etapa do tratamento, à obesidade e à sensibilização alérgica. RESULTADOS: Foram analisados 300 pacientes com asma (1,38M:1F), com mediana de idade de 10,8 anos, e de início dos sintomas de 1,0 ano. A atopia estava presente em 78% dos pais e/ou irmãos. Antecedentes pessoais de doenças alérgicas ocorreram em 292 pacientes (96% rinite, 27% dermatite atópica, 18% conjuntivite alérgica, 6% alergia alimentar). Foram diagnosticados sete casos de deficiência de IgA (DIgA) e quatro de IgG2; obesidade em 37/253 (15%), sendo que sobrepeso e obesidade estiveram associados à falta de controle (p=0,023). Em 118 pacientes com multissensibilização, predominaram casos não controlados (22 (19%) casos; p=0,049; OR 1,9; IC95% 1,03-3,50). Entre os 180 casos (60%) em tratamento nas etapas 3 e 4, 122 (45%) estavam controlados e 112 (41%) parcialmente controlados. CONCLUSÕES: A rinite foi a alergia mais associada à asma e a prevalência de DIgA foi 20 vezes maior do que na população geral. O controle parcial ou total dos sintomas da asma foi obtido em 85% dos casos. Obesidade/sobrepeso e multissensibilização foram associadas à falta de controle da asma.

Estrogen increases nitric-oxide production in human bronchial epithelium

Although sex differences in asthma severity are recognized, the mechanisms by which sex steroids such as estrogen influence the airway are still under investigation. Airway tone, a key aspect of asthma, represents a balance between bronchoconstriction and dilation. Nitric oxide (NO) from the bronchial epithelium is an endogenous bronchodilator. We hypothesized that estrogens facilitate bronchodilation by generating NO in bronchial epithelium. In acutely dissociated human bronchial epithelial cells from female patients exposure to 17β-estradiol (E(2); 10 pM-100 nM) resulted in rapid increase of diaminofluorescein fluorescence (NO indicator) within minutes, comparable with that induced by ATP (20 μM). Estrogen receptor (ER) isoform-specific agonists (R,R)-5,11-diethyl-5,6,11,12-tetrahydro-2,8-chrysenediol (THC) (ERα) and diaryl-propionitrile (DPN) (ERβ) stimulated NO production to comparable levels and at comparable rates, whereas the ER antagonist 7α,17β-[9-[(4,4,5,5,5-pentafluoropentyl)sulfinyl]nonyl]estra-1,3,5(10)-triene-3,17-diol (ICI 182,780) (1 μM) was inhibitory. Estrogen effects on NO were mediated via caveolin-1 (blocked using the caveolin-1 scaffolding domain peptide) and by increased intracellular calcium concentration [prevented by 20 μM 1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid tetra(acetoxymethyl) ester but not by blocking Ca(2+) influx using LaCl(3)]. Estrogen increased endothelial NO synthase activation (inhibited by 100 μM N(G)-nitro-l-arginine methyl ester) and phosphorylated Akt. In epithelium-intact human bronchial rings contracted with acetylcholine (1 μM), E(2), THC, and DPN all produced acute bronchodilation in a dose-dependent fashion. Such bronchodilatory effects were substantially reduced by epithelial denudation. Overall, these data indicate that estrogens, acting via ERα or ERβ, can acutely produce NO in airway epithelium (akin to vascular endothelium). Estrogen-induced NO and its impairment may contribute to altered bronchodilation in women with asthma.

Ethnicity and risk of hospitalization for asthma and chronic obstructive pulmonary disease

PURPOSE

To identify ethnic differences for risk of hospitalization for asthma and chronic obstructive pulmonary disease (COPD).

METHODS

We undertook a cohort study with 126,019 participants: 55% whites, 27% blacks, 11% Asians, and 4% Hispanics. To estimate asthma and COPD risk, we used Cox proportional hazards models adjusted for age, sex, body mass index, education, smoking, and alcohol intake. End points were hospitalizations for asthma or COPD.

RESULTS

Compared with whites, relative risks (RR) with 95% confidence intervals (95% CI) for asthma among other groups were: blacks, 1.7 (1.4-2.0); Hispanics, 0.9 (0.6-1.4); and Asians, 1.6 (1.2-2.1). Among Asians, increased risk was concentrated in Filipino men and women and South Asian men. For COPD, whites were at highest risk; RR of blacks was 0.9 (0.7-1.0); Hispanics, 0.6 (0.3- 0.9); and Asians, 0.4 (0.3-0.6). COPD risk among Asians was lowest in Chinese with RR of 0.3 (0.1-0.5).

CONCLUSIONS

Ethnic disparities in risk of asthma and COPD as well as between both diseases exist, especially for Asian Americans, who have high asthma risk and low COPD risk. While residual confounding for smoking or other environmental factors could be partially responsible, genetic factors in Asians may be involved in decreased COPD risk.

Determinants of experimental allergic responses: interactions between allergen dose, sex and age

The prevalence of allergic diseases is influenced by sex and age. Although mouse models are widely used in allergy research, few experimental studies have examined the interaction effects of sex and age on allergy outcomes. Our aim was to investigate the individual and combined effects of sex and age on allergic sensitization and inflammation in two mouse models: an intraperitoneal (i.p.) and an intranasal (i.n.) sensitization model. We also investigated how the allergen immunization dose interacted with age and sex in the i.p. model. Female and male mice were immunized i.p. or i.n. with ovalbumin when 1, 6 or 20 weeks old. In both models, allergen challenges were performed by i.n. delivery. Serum antibodies, draining lymph node cytokine release and airway inflammatory responses were assessed. In the i.p. model, the antibody and cytokine levels and airway inflammation were highly influenced by immunization dose and age. The responses increased with age when using a low immunization dose, but decreased with age when using a high immunization dose. In the i.n. model, antibody production and airway tissue inflammation increased with age. Female compared with male mice generally developed more pronounced antibody and inflammatory responses. Relative to older mice, juvenile mice had augmented airway inflammation to allergen exposures. The study demonstrates that immunization dose, sex and age are highly influential on allergy outcomes. To better mimic different life stages of human allergic airway disease, murine models, therefore, require careful optimization.

Sex-specific trends in prevalence of childhood asthma over 30 years in Patras, Greece

AIM

 According to four surveys conducted during 1978-2003, the prevalence of childhood asthma and wheezing has risen in the city of Patras, Greece, albeit at a decelerating rate. We examined sex-specific wheeze and asthma prevalence in the same urban environment in 2008.

METHODS

A cross-sectional parental questionnaire survey was performed in 2008 among third and fourth grade schoolchildren (8-9 year old), which was identical to previously conducted surveys in 1978 (n = 3003), 1991 (n = 2417), 1998 (n = 3076) and 2003 (n = 2725).

RESULTS

The prevalence of current wheeze and asthma in 1978, 1991, 1998, 2003 and 2008 (n = 2688) was 1.5%, 4.6%, 6.0%, 6.9% and 6.9%, respectively (p for trend <0.001). Respective values for lifetime (ever had) wheeze and asthma in the 1991-2008 surveys were 8.0%, 9.6%, 12.4% and 12.6% (p for trend <0.001). The male:female ratio of current and lifetime wheeze and asthma increased during the 30-year surveillance period (p for trend <0.001). Irrespective of sex, diagnosed asthma declined among current wheezers by 17% (p < 0.001), but not among non-current ones (6.7%, p = 0.16) during 2003-2008.

CONCLUSIONS

Childhood wheeze and asthma have reached a plateau in an urban environment in Greece, while the male:female ratio increased. Asthma diagnosis declined among schoolage but not preschool wheezers during 2003-2008.

Exposure assessment in cohort studies of childhood asthma

BACKGROUND

The environment is suspected to play an important role in the development of childhood asthma. Cohort studies are a powerful observational design for studying exposure-response relationships, but their power depends in part upon the accuracy of the exposure assessment.

OBJECTIVE

The purpose of this paper is to summarize and discuss issues that make accurate exposure assessment a challenge and to suggest strategies for improving exposure assessment in longitudinal cohort studies of childhood asthma and allergies.

DATA SYNTHESIS

Exposures of interest need to be prioritized, because a single study cannot measure all potentially relevant exposures. Hypotheses need to be based on proposed mechanisms, critical time windows for effects, prior knowledge of physical, physiologic, and immunologic development, as well as genetic pathways potentially influenced by the exposures. Modifiable exposures are most important from the public health perspective. Given the interest in evaluating gene-environment interactions, large cohort sizes are required, and planning for data pooling across independent studies is critical. Collection of additional samples, possibly through subject participation, will permit secondary analyses. Models combining air quality, environmental, and dose data provide exposure estimates across large cohorts but can still be improved.

CONCLUSIONS

Exposure is best characterized through a combination of information sources. Improving exposure assessment is critical for reducing measurement error and increasing power, which increase confidence in characterization of children at risk, leading to improved health outcomes.

Analysis of sex and gender-specific research reveals a common increase in publications and marked differences between disciplines

BACKGROUND

The incorporation of sex and gender-specific analysis in medical research is increasing due to pressure from public agencies, funding bodies, and the clinical and research community. However, generations of knowledge and publication trends in this discipline are currently spread over distinct specialties and are difficult to analyze comparatively.

METHODS

Using a text-mining approach, we have analysed sex and gender aspects in research within nine clinical subspecialties--Cardiology, Pulmonology, Nephrology, Endocrinology, Gastroenterology, Haematology, Oncology, Rheumatology, Neurology--using six paradigmatic diseases in each one. Articles have been classified into five pre-determined research categories--Epidemiology, Pathophysiology, Clinical research, Management and Outcomes. Additional information has been collected on the type of study (human/animal) and the number of subjects included. Of the 8,836 articles initially retrieved, 3,466 (39%) included sex and gender-specific research and have been further analysed.

RESULTS

Literature incorporating sex/gender analysis increased over time and displays a stronger trend if compared to overall publication increase. All disciplines, but cardiology (22%), demonstrated an underrepresentation of research about gender differences in management, which ranges from 3 to 14%. While the use of animal models for identification of sex differences in basic research varies greatly among disciplines, studies involving human subjects are frequently conducted in large cohorts with more than 1,000 patients (24% of all human studies).

CONCLUSIONS

Heterogeneity characterizes sex and gender-specific research. Although large cohorts are often analysed, sex and gender differences in clinical management are insufficiently investigated leading to potential inequalities in health provision and outcomes.

Gender-specific asthma treatment

Because genetic characteristics vary among subjects, the therapeutic effects of a certain drug differ among patients with the same disease. For this reason, special interest has focused on tailored treatments. Although it is well known that sex is genetically determined, little attention has been paid to sex differences in the clinical features and treatment of asthma. Females are more likely to suffer allergic asthma, to have difficulty controlling asthma symptoms, and to show adverse effects to drugs. As asthma symptoms show cyclic changes depending on female hormone levels in many women of child-bearing age, the use of contraceptives may specifically help to treat female patients with asthma such as those with perimenstrual asthma and severe asthma. Generally, testosterone seems to suppress asthma, and dehydroepiandrosterone (DHEA), a less virilizing androgen, may be effective for treating asthma. Evidence exists for a therapeutic and steroid-sparing effect of DHEA. However, further studies on the optimal dose and route of DHEA for each sex are needed. Monitoring of the serum DHEA-S level is necessary for patients with asthma on inhaled steroid treatment, and at minimum, replacement therapy for patients with a low level of DHEA may be helpful for treating their asthma.

Gender differences in asthma development and remission during transition through puberty: the TRacking Adolescents' Individual Lives Survey (TRAILS) study

BACKGROUND

During puberty, a gender shift in asthma prevalence occurs, with a preponderance of boys before puberty. The mechanisms underlying this gender shift are unclear.

OBJECTIVES

We assessed associations of pubertal stages and transition through puberty with (1) the prevalence, incidence, and remission of asthma in male and female subjects; (2) total IgE levels; and (3) peak expiratory flow (PEF) fall during a shuttle run test (SRT).

METHODS

In the TRacking Adolescents' Individual Lives Survey study (n = 2,230; 51% female subjects), associations between pubertal stages and the prevalence, incidence, and remission of asthma were tested by using logistic regression and generalized estimating equations at a mean age of 11.1 (SD, 0.6), 13.6 (SD, 0.5), and 16.3 (SD, 0.7) years. Multiple linear regression analyses were used to study log-transformed total IgE levels and PEF fall during a SRT dependent on early versus late pubertal stages at a mean age of 16.3 years.

RESULTS

The prevalence of asthma was similar in boys (7.7%) and girls (7.4%) at a mean age of 11.1 years. The prevalence of asthma was significantly higher in female (6.2%) than male (4.3%) subjects at 16.3 years of age. There were no significant associations between transition of pubertal stages and the presence of asthma, either cross-sectionally or longitudinally. Pubertal stages and log-transformed total IgE levels or PEF fall during a SRT at age 16.3 years were not correlated.

CONCLUSIONS

A shift in the prevalence of asthma occurs between 11.1 and 16.3 years, which is due to both an increased incidence and decreased remission of asthma in female compared with male subjects. Pubertal stages could not be proved to explain the gender shift in asthma prevalence.

Self-reported prevalence of childhood allergic diseases in three cities of China: a multicenter study

BACKGROUND

Several studies conducted during the 1990s indicated that childhood allergic diseases were increasing worldwide, but more recent investigations in some Western countries have suggested that the trend is stabilizing or may even be reversing. However, few data are available on the current status of allergic disease prevalence in Chinese children. The aim of the present study was to investigate the prevalence rates of asthma, allergic rhinitis, and eczema in children of three major cities of China, to determine the status of allergic diseases among Chinese children generally, and to evaluate the prevalence of allergic diseases in children of different ages.

METHODS

We conducted a cross-sectional survey between October 2008 and May 2009 in three major cities of China (Beijing, Chongqing, and Guangzhou) to evaluate the prevalence rates of childhood allergic diseases including asthma, allergic rhinitis, and eczema, using a questionnaire of the International Study of Asthma and Allergies in Childhood (ISAAC) group. A total of 24,290 children aged 0-14 years were interviewed, using a multi-stage sampling method. To acquire data on children aged 3-14 years, we visited schools and kindergartens. To access children too young to attend school or kindergarten, we extended our survey to community health service centers. Each questionnaire was completed by a parent or guardian of a child after an informed consent form was signed.

RESULTS

Of the 24,290 children in our study, 12,908 (53.14%) were males and 11,382 (46.86%) females; 10,372 (42.70%) were from Beijing, 9,846 (40.53%) from Chongqing, and 4,072 (16.77%) from Guangzhou. Our survey indicated that in Beijing, Chongqing, and Guangzhou, the prevalence rates of asthma were 3.15%, 7.45%, and 2.09%, respectively; the rates of allergic rhinitis were 14.46%, 20.42%, and 7.83%; and the rates of eczema were 20.64%, 10.02%, and 7.22%. The prevalence of allergic diseases varied with age. Asthma was relatively less common both in children aged under 2 years, and in those aged 9 years or more, in each of the three cities. The prevalence of allergic rhinitis was also lower in children younger than 2 years. The prevalence of eczema fell with age.

CONCLUSIONS

A marked increase in the prevalence rates of allergic diseases in China (compared with earlier data) was evident. Further studies exploring the precise causes of this increase are warranted.

The influence of gender on adults admitted for asthma

BACKGROUND

In the United States, the prevalence of asthma is not only higher than in most other countries, it also varies greatly between diverse populations. Only limited data exist that examine the variation of outcomes by gender in patients admitted to a hospital for asthma.

OBJECTIVE

This study assessed outcome differences based on gender in adults who were admitted nationally with the primary diagnosis of asthma.

METHODS

A retrospective cohort study was conducted of all patients who were admitted to a hospital with the primary diagnosis of asthma in 2002-2005 and were reported in the Nationwide Inpatient Sample of the Healthcare Cost and Utilization Project. Patients were excluded if they were aged <18 years or had an additional diagnosis of chronic obstructive pulmonary disease.

RESULTS

A total of 590,410 patients (439,991 women, 150,419 men) were included in the study. Patients admitted for asthma were significantly more likely to be female (P < 0.05). Women were significantly older compared with men (mean [SD], 48.5 [17.4] vs 44.6 [17.0] years, respectively), had a longer length of stay (3.44 vs 2.84 days), were more likely to be white (37.9% vs 34.2%), and had a higher total cost of admission ($10,575 vs $9390) (all, P < 0.05). Women were more likely than men to need a tracheostomy (adjusted odds ratio [AOR] = 2.04; 95% CI, 1.77-2.35) and to have a bronchoscopy (AOR =1.12; 95% CI, 1.05-1.21). Men were significantly more likely than women to have arterial blood gases performed (AOR = 1.15; 95% Cl, 1.05-1.27) and to be intubated (AOR = 1.18; 95% Cl, 1.10-1.26) (both, P < 0.05). Men were significantly more likely to be admitted as an emergency admission (AOR = 1.10; 95% Cl, 1.04-1.18) and to die during hospitalization (AOR =1.69; 95% CI, 1.41-2.03).

CONCLUSION

Although they were less likely to be admitted to a hospital, men were more likely to be admitted as an emergency and to experience worse outcomes compared with women, in this study of adults with asthma in the United States.

Differences in associations between markers of antioxidative defense and asthma are sex specific

BACKGROUND

Lungs are exposed to high levels of oxygen, air pollutants, and smoke, all of which stimulate the production of reactive oxygen species (ROS). In addition, inflammatory cells produce ROS, and thus there may be increased demand for antioxidants, including antioxidant enzymes, in inflammatory lung diseases such as asthma. Sex-specific differences have been noted for asthma, which in postpubertal subjects is predominantly found in females. These sex-specific differences may be associated with differences on the molecular level as well.

OBJECTIVE

The aim of this cross-sectional study was to examine associations between markers of antioxidative defense and asthma, and to investigate whether these associations were different between women and men.

METHODS

Based on the European Community Respiratory Health Survey protocol, subjects were enrolled in a study of asthma risk factors. The multicenter study was conducted in 5 west Danish counties between 2003 and 2006, and the subjects were recruited as a case-enriched random sample of 10,000 Danish inhabitants aged 20 to 44 years selected by their civil registration number. Participants were identified by positive answers to asthma questions on a screening questionnaire, random sampling, or both. Serum selenium concentrations and antioxidant enzyme activities (superoxide dismutase, glutathione peroxidase [GPX], glutathione reductase [GR], and glucose-6-phosphate dehydrogenase [G6PD]) in erythrocytes were measured. Asthma was defined as either current asthma symptoms with bronchial hyperresponsiveness (BHR) or a continuous asthma score based on 8 questions.

RESULTS

A total of 1191 mostly white women and men (mean [SD] age, 34.0 [7.1] and 35.1 [7.1] years, respectively) were enrolled in the study. Current asthma symptoms were present in 29.9% (200/670) of women and 22.5% (117/521) of men, with women reporting more positive answers (51.1% vs 40.9%, respectively; P < 0.01) to asthma questions. Serum selenium concentrations were measured in 1151 subjects (640 women, 511 men), and antioxidant enzyme activities were measured in 295 subjects (161 women, 134 men). Women had higher enzyme activities of most antioxidant enzymes (GPX, P = 0.006; GR, P < 0.001; and G6PD, P = 0.009) than did men. Although the serum selenium concentration was inversely associated with asthma in both sexes, there was a female preponderance, with 3.5% lower serum selenium in subjects with current asthma symptoms with BHR (n = 77) compared with controls (n = 287). GR activity was associated with asthma in men, with 5.7% higher enzyme activity in subjects with current asthma symptoms with BHR (n = 14) compared with controls (n = 77). However, a significant interaction with gender was observed for analyses of GR (P = 0.02), but not for analyses of selenium.

CONCLUSIONS

In this study of asthma risk factors, women had higher levels of enzyme activities than did men in a randomly selected Danish population, and sex-specific differences were found in the associations between markers of antioxidative defense and asthma.

A current picture of asthma diagnosis, severity, and control in a low-income minority preteen population

BACKGROUND

Asthma severity, control, type of medical regimen provided, and compliance with it are not well understood in minority patients at the transition stage from childhood to adolescence.

OBJECTIVE

Describe the level of asthma severity and control and the clinical regimens provided to a large population of low-income, African American children at this developmentally significant period.

METHODS

Parents of 1292 children with asthma among 6827 preteens in 19 middle schools in predominantly African American (94%), low-income neighborhoods in Detroit, Michigan, were enrolled in the study. Data were collected through self-administered survey and telephone interviews and were useable for 936 participants. Study queries related to demographics, asthma symptoms, and medication use. Mixed effects models with a random intercept for school were used to determine severity and control and the association of medical regimens to these.

RESULTS

Sixty-seven percent of children with probable asthma had received a physician's diagnosis. Being female was associated with being undiagnosed (p = .02). Forty-seven with no diagnosis had persistent asthma and 10% of these were classified as severe. Sixty-eight percent with a diagnosis and asthma medicine prescriptions were not controlled. Compliant use of controller medicine was associated with poorer asthma control compared to noncompliant controller users (p = .04) and reliever-only users (p < .001). Thirty-nine percent of children had controller medicine; of those 40% were not compliant with controller use; 9% nebulized their controller medicine.

CONCLUSIONS

Care provided low-income minority children at an important stage in their development was not consistent with guidelines for asthma control. Therapy choices for treatment did not account for the actual level of their symptoms. Lack of an asthma diagnosis was significant in the population. Adolescent girls were at risk for not receiving a diagnosis. Patient compliance with asthma regimens was limited. Both clinician and patient education regarding effective asthma management appears needed regarding preteens in low-income minority communities.

Dampness, food habits, and sick building syndrome symptoms in elementary school pupils

OBJECTIVES

We investigated dampness/mold in schools and dwellings, and food habits and subjective symptoms in elementary school pupils, in order to clarify the effect of dampness and food habits on subjective symptoms in elementary school pupils.

METHODS

Questionnaires were used to investigate dampness in classrooms and dwellings in Hokkaido, Japan, and its effect on subjective symptoms in 1,077 pupils in 8 elementary schools. We used a dampness index for both the home and classroom; the index was the sum of the presence of four dampness indicators: (1) visible mold, (2) moldy odor, (3) water leakage, and (4) condensation on windowpanes. The questionnaire also contained queries about food habits, as follows: the frequency of eating breakfast, whether the energy provided by the school lunch was sufficient, and whether eating too many snacks and/or sweets were consumed. Adjusted logistic regression was used to determine whether dampness and food habits were related to the subjective symptoms.

RESULTS

In fully adjusted models, the home dampness index was significantly related to cough, general symptoms, and having at least one symptom; the classroom dampness index was significantly related to nasal symptoms. In addition, usually not eating breakfast was significantly related to eye symptoms, and too many snacks and/or sweets was significantly related to eye, nasal, and general symptoms.

CONCLUSIONS

Both home and classroom dampness can affect pupils' health. Home dampness, in particular, was significantly related to cough and general symptoms, and classroom dampness was significantly related to nasal symptoms. Furthermore, favorable food habits have a positive effect on pupils' subjective symptoms.

Hormonal influences on lung function and response to environmental agents: lessons from animal models of respiratory disease

Numerous studies in humans and experimental animals have identified considerable sex differences in respiratory physiology and in the response of the lung to environmental agents. These differences appear to be mediated, at least in part, by sex hormones and their nuclear receptors. Moreover, animal models are increasingly used to study pathogenic mechanisms and test potential therapies for a variety of human lung diseases, many of which appear to be influenced by sex and sex hormones. In this article, data are summarized from studies of lung function and disease in which sex differences have been observed. Specific attention is paid to animal models of acute lung injury, nonallergic and allergic lung inflammation, and lung fibrosis. It is anticipated that continued investigation of the role of sex and sex hormones in animal models will provide valuable insight into the pathogenesis and potential treatments for a variety of acute and chronic human lung diseases.

Postmenopausal hormone therapy and asthma onset in the E3N cohort

BACKGROUND

Epidemiological studies have suggested that female hormones might play a role in asthma and that menopausal hormone therapy (MHT or hormone replacement therapy (HRT)) might increase the risk of asthma in postmenopausal women. The only prospective study addressing this issue reports an increase in the risk of developing asthma which was similar for oestrogen alone and oestrogen/progestagen treatment.

METHODS

The association between the use of different types of MHT and the risk of asthma onset in postmenopausal women was investigated prospectively from 1990 to 2002 by biennial questionnaires as part of the French E3N cohort study. Asthma onset was considered to be the time of medical diagnosis of asthma cases occurring during the follow-up of women who were asthma free at baseline. Cox proportional hazards models were used, adjusting for potential confounding factors.

RESULTS

Among 57 664 women free of asthma at menopause, 569 incident cases of asthma were identified during 495 448 years of follow-up. MHT was related to an increased risk of asthma onset (HR=1.20, 95% CI 0.98 to 1.46) among recent users. The increase in risk of asthma onset was only significant among women reporting the use of oestrogen alone (HR=1.54, 95% CI 1.13 to 2.09) particularly in never smokers (HR=1.80, 95% CI 1.15 to 2.80) and women reporting allergic disease prior to asthma onset (HR=1.86, 95% CI 1.18 to 2.93). A small increase in the risk of asthma onset associated with the use of oestrogen/progestagen was also observed in these subgroups.

CONCLUSION

Postmenopausal use of oestrogen alone was associated with an increased rate of newly diagnosed asthma in menopausal women.

Rapid effects of estrogen on intracellular Ca2+ regulation in human airway smooth muscle

The severity of asthma, a disease characterized by airway hyperresponsiveness and inflammation, is enhanced in some women during the menstrual cycle and during pregnancy but relieved in others. These clinical findings suggest that sex steroids modulate airway tone. Based on well-known relaxant effects of estrogens on vascular smooth muscle, we hypothesized that estrogens relax airway smooth muscle (ASM), thus facilitating bronchodilation. In ASM tissues from female patients, Western and immunocytochemical analyses confirmed the presence of both estrogen receptor (ER) isoforms, ERalpha and ERbeta. In fura 2-loaded, dissociated ASM cells maintained in culture, acute exposure to physiological concentrations of 17beta-estradiol (E(2); 100 pM to 10 nM) decreased the intracellular Ca(2+) ([Ca(2+)](i)) response to 1 muM histamine, an effect reversed by the ER antagonist ICI-182,780. The ERalpha-selective agonist (R,R)-THC had a greater reducing effect on [Ca(2+)](i) responses to histamine and 1 muM ACh compared with the ERbeta-selective agonist (DPN). The effects of E(2) on [Ca(2+)](i) were mediated, at least in part, via decreased Ca(2+) influx through l-type channels and store-operated Ca(2+) entry but not via Ca(2+)-activated K(+) channels, receptor-operated entry, or sarcoplasmic reticulum reuptake. Overall, these data support our hypothesis that estrogens relax ASM and suggest a potentially novel therapeutic target in airway hyperresponsiveness.

A new look at the pathogenesis of asthma

Asthma is an inflammatory disorder of the conducting airways that has strong association with allergic sensitization. The disease is characterized by a polarized Th-2 (T-helper-2)-type T-cell response, but in general targeting this component of the disease with selective therapies has been disappointing and most therapy still relies on bronchodilators and corticosteroids rather than treating underlying disease mechanisms. With the disappointing outcomes of targeting individual Th-2 cytokines or manipulating T-cells, the time has come to re-evaluate the direction of research in this disease. A case is made that asthma has its origins in the airways themselves involving defective structural and functional behaviour of the epithelium in relation to environmental insults. Specifically, a defect in barrier function and an impaired innate immune response to viral infection may provide the substrate upon which allergic sensitization takes place. Once sensitized, the repeated allergen exposure will lead to disease persistence. These mechanisms could also be used to explain airway wall remodelling and the susceptibility of the asthmatic lung to exacerbations provoked by respiratory viruses, air pollution episodes and exposure to biologically active allergens. Variable activation of this epithelial-mesenchymal trophic unit could also lead to the emergence of different asthma phenotypes and a more targeted approach to the treatment of these. It also raises the possibility of developing treatments that increase the lung's resistance to the inhaled environment rather than concentrating all efforts on trying to suppress inflammation once it has become established.