Christian B. Pipper

Chromosome 17q21 Gene Variants Are Associated with Asthma and Exacerbations but Not Atopy in Early Childhood

RATIONALE An asthma predisposition locus on chromosome 17q12-q21 has recently been replicated in different ethnic groups. OBJECTIVES To characterize the asthma and atopy phenotypes in early childhood that associate with the 17q12-21 locus. METHODS The single nucleotide polymorphism (SNP), rs7216389, was genotyped in 376 of 411 children from the Copenhagen Prospective Study on Asthma in Childhood (COPSAC) birth cohort born to mothers with asthma together with 305 mothers and 224 fathers. Nineteen additional SNPs in the region were genotyped in the children. Investigator-diagnosed clinical endpoints were based on diary cards and clinic visits every 6 months and at acute symptoms from birth. Lung function, bronchial responsiveness, and sensitization were tested longitudinally from early infancy. MEASUREMENTS AND MAIN RESULTS rs7216389 was significantly associated with the development of wheeze (hazard ratio 1.64 [1.05-2.59], P value = 0.03), asthma (hazard ratio, 1.88 [1.15-3.07], P = 0.01), and acute severe exacerbations (hazard ratio 2.66 [1.58-4.48], P value = 0.0002). The effect on wheeze and asthma was observed for early onset but not late onset of disease. The increased risk of exacerbations persisted from 1 to 6 years of age (incidence ratio 2.48 [1.42-4.32], P value = 0.001), and increased bronchial responsiveness was present in infancy and at 4 years of age, but not at 6 years. In contrast, rs7216389 conferred no risk of eczema, rhinitis, or allergic sensitization. CONCLUSIONS Variation at the chromosome 17q12-q21 locus was associated with approximately twofold increased risk of recurrent wheeze, asthma, asthma exacerbations, and bronchial hyperresponsiveness from early infancy to school age but without conferring risk of eczema, rhinitis, or allergic sensitization. These longitudinal clinical data show this locus to be an important genetic determinant of nonatopic asthma in children.

Diabetes Is a Risk Factor for Pulmonary Tuberculosis: A Case-Control Study from Mwanza, Tanzania

Background Diabetes and TB are associated, and diabetes is increasingly common in low-income countries where tuberculosis (TB) is highly endemic. However, the role of diabetes for TB has not been assessed in populations where HIV is prevalent. Methods A case-control study was conducted in an urban population in Tanzania among culture-confirmed pulmonary TB patients and non-TB neighbourhood controls. Participants were tested for diabetes according to WHO guidelines and serum concentrations of acute phase reactants were measured. The association between diabetes and TB, and the role of HIV as an effect modifier, were examined using logistic regression. Since blood glucose levels increase during the acute phase response, we adjusted for elevated serum acute phase reactants. Results Among 803 cases and 350 controls the mean (SD) age was 34.8 (11.9) and 33.8 (12.0) years, and the prevalence of diabetes was 16.7% (95% CI: 14.2; 19.4) and 9.4% (6.6; 13.0), respectively. Diabetes was associated with TB (OR 2.2, 95% CI: 1.5; 3.4, p<0.001). However, the association depended on HIV status (interaction, p = 0.01) due to a stronger association among HIV uninfected (OR 4.2, 95% CI: 1.5; 11.6, p = 0.01) compared to HIV infected (OR 0.1, 95% CI: 0.01; 1.8, p = 0.13) after adjusting for age, sex, demographic factors and elevated serum acute phase reactants. Conclusion Diabetes is a risk factor for TB in HIV uninfected, whereas the association in HIV infected patients needs further study. The increasing diabetes prevalence may be a threat to TB control.

Community analysis of bacteria colonizing intestinal tissue of neonates with necrotizing enterocolitis

BackgroundNecrotizing enterocolitis (NEC) is the most common gastrointestinal emergency in newborn neonates. Bacteria are believed to be important in the pathogenesis of NEC but bacterial characterization has only been done on human faecal samples and experimental animal studies. The aim of this study was to investigate the microbial composition and the relative number of bacteria in inflamed intestinal tissue surgically removed from neonates diagnosed with NEC (n = 24). The bacterial populations in the specimens were characterized by laser capture microdissection and subsequent sequencing combined with fluorescent in situ hybridization (FISH), using bacterial rRNA-targeting oligonucleotide probes.ResultsBacteria were detected in 22 of the 24 specimens, 71% had moderate to high densities of bacteria. The phyla detected by 16S rRNA gene sequencing were: Proteobacteria (49.0%), Firmicutes (30.4%), Actinobacteria (17.1%) and Bacteroidetes (3.6%). A major detected class of the phylum Proteobacteria belonged to δ-proteobacteria. Surprisingly, Clostridium species were only detected in 4 of the specimens by FISH, but two of these specimens exhibited histological pneumatosis intestinalis and both specimens had a moderate to a high density of C. butyricum and C. parputrificum detected by using species specific FISH probes. A 16S rRNA gene sequence tag similar to Ralstonia species was detected in most of the neonatal tissues and members of this genus have been reported to be opportunistic pathogens but their role in NEC has still to be clarified.ConclusionIn this study, in situ identification and community analysis of bacteria found in tissue specimens from neonates with NEC, were analysed for the first time. Although a large variability of bacteria was found in most of the analyzed specimens, no single or combination of known potential pathogenic bacteria species was dominating the samples suggestive NEC as non-infectious syndrome. However there was a significant correlation between the presence of C. butyricum & C. parputrificum and histological pneumatosis intestinalis. Finally this study emphasizes the possibility to examine the microbial composition directly on excised human tissues to avoid biases from faecal samples or culturing.

Endotyping early childhood asthma by quantitative symptom assessment

BACKGROUND Asthmatic symptoms in young children reflect a heterogeneous group of diseases. Symptoms remain the primary end-point in both research and clinical management, but there is a need for standardized symptom assessment. OBJECTIVE We sought to explore endotyping of early childhood asthma by prospective daily diary recordings of globally assessed symptoms during the first 6 years of life. METHODS Globally assessed troublesome lung symptoms were recorded in daily diaries during the first 6 years of life in the Copenhagen Prospective Studies on Asthma in Childhood birth cohort born of mothers with asthma. Symptom recordings adjusted for missing values were used to categorize children based on the temporal symptom pattern. We propose an alternative approach of quantitating symptom frequency and longitudinal assessment of age-at-onset to segment children. These different methods were compared by estimating the risk from the well-established genetic risk variants of ORMDL3. RESULTS Six years of daily diary recordings were available in 307 children (75% of the birth cohort). We confirmed the archetypal temporal categories of transient early, persistent, and late-onset troublesome lung symptoms based on 3-year periods, finding no benefit from a finer temporal categorization of 2- or 1-year periods. Restricting categorization to symptoms during the summer improved specificity at the expense of sensitivity. Our alternative approach quantitating symptom frequency and age-at-onset exhibited a more powerful association with ORMDL3, whereas the study power was lost by restricting to doctor-verified wheeze. CONCLUSIONS We propose a novel method for endotyping of early childhood asthma based on the frequency and age-of-onset of globally assessed troublesome lung symptoms analyzed longitudinally. This method showed the closest association with genetic variants, hence underlying molecular mechanisms and endotypes.

Azithromycin for episodes with asthma-like symptoms in young children aged 1–3 years: a randomised, double-blind, placebo-controlled trial

Summary Background Bacteria and viruses are equally associated with the risk of acute episodes of asthma-like symptoms in young children, suggesting antibiotics as a potential treatment for such episodes. We aimed to assess the effect of azithromycin on the duration of respiratory episodes in young children with recurrent asthma-like symptoms, hypothesising that it reduces the duration of the symptomatic period. Methods In this randomised, double-blind, placebo-controlled trial, we recruited children aged 1–3 years, who were diagnosed with recurrent asthma-like symptoms from the Copenhagen Prospective Studies on Asthma in Childhood 2010 cohort; a birth cohort consisting of the general Danish population of Zealand, including Copenhagen. Exclusion criteria were macrolide allergy, heart, liver, neurological, and kidney disease, and, before each treatment, one or more clinical signs of pneumonia (respiratory frequency of ≥50 breaths per min; fever of ≥39°C; C-reactive protein concentration of ≥476·20 nmol/L [≥50 mg/L]). Each episode of asthma-like symptoms lasting at least 3 days was randomly allocated to a 3-day course of azithromycin oral solution of 10 mg/kg per day or placebo after thorough examination by a study physician at the Copenhagen Prospective Studies on Asthma research unit. Each episode was randomly allocated independently of previous treatment from a computer-generated list of random numbers in blocks of ten (generated at the Pharmacy of Glostrup). Investigators and children were masked until the youngest child turned 3 years of age and throughout the data validation and analysis phases. The primary outcome was duration of the respiratory episode after treatment, verified by prospective daily diaries and analysed with Poisson regression. Analyses were per protocol (excluding those without a primary outcome measure or who did not receive treatment). This trial is registered with ClinicalTrials.gov, number NCT01233297. Findings Between Nov 17, 2010, and Jan 28, 2014, we randomly allocated 158 asthma-like episodes in 72 children (79 [50%] to azithromycin and 79 [50%] to placebo). The mean duration of the episode after treatment was 3·4 days for children receiving azithromycin compared with 7·7 days for children receiving placebo. Azithromycin caused a significant shortening of the episode of 63·3% (95% CI 56·0–69·3; p<0·0001). The effect size increased with early initiation of treatment, showing a reduction in episode duration of 83% if treatment was initiated before day 6 of the episode compared with 36% if initiated on or after day 6 (p<0·0001). We noted no differences in clinical adverse events between the azithromycin (18 [23%] of 78 episodes included in final analysis) and placebo (24 [30%] of 79) groups (p=0·30), but we did not investigate bacterial resistance patterns after treatment. Interpretation Azithromycin reduced the duration of episodes of asthma-like symptoms in young children, suggesting that this drug could have a role in acute management of exacerbations. Further research is needed to disentangle the inflammatory versus antimicrobial aspects of this relation. Funding Lundbeck Foundation, Danish Ministry of Health, Danish Council for Strategic Research, Capital Region Research Foundation.

Prevalence of hypertrophic cardiomyopathy in a cohort of British Shorthair cats in Denmark.

BACKGROUND Familial hypertrophic cardiomyopathy (HCM) has been described previously in British Shorthair cats (BSH), but until now, no reports have been published describing the prevalence of the disease within this breed. OBJECTIVES The aim of this study was to assess the prevalence of HCM in a large cohort of BSH and to evaluate the effect of sex, weight, and increasing age as potential risk factors for this disease. ANIMALS Three hundred and twenty-nine BSH presented for routine HCM screening during a 4-year period. METHODS Prospective cross-sectional study in which all cats were screened for HCM by conventional echocardiography. RESULTS A total of 329 cats were examined, 214 females and 115 males, with a median age of 2.3 years (range, 0.8-14.1). Twenty-eight cats (8.5%) were classified as HCM-positive, 14 (4.3%) as equivocal, 282 (85.7%) as HCM-negative, and 5 (2.1%) were diagnosed with other cardiac diseases. The median age for diagnosis of HCM was 2.7 years (range, 0.9-14.1). Male cats had a significantly higher occurrence of HCM (20.4%) compared with the females (2.1%) corresponding to an odds ratio of 7.89 (95 % CI, 2.54-28.08) for males versus females adjusted for age and weight (P < .001). CONCLUSION The BSH in our cohort had a high prevalence of HCM, often of early onset and with a significant male sex predisposition. We strongly recommend echocardiographic screening in this breed, especially cats used for breeding.

Maternal obesity and offspring dietary patterns at 9 months of age

Background/Objectives:Differences in the quality of complementary feeding between infants of obese and nonobese mothers have not been examined sufficiently. The aim of this paper was to compare dietary patterns, foods, nutrients and energy intakes of 9-month-old Danish infants in a cohort comprising obese mothers (SKOT II, n=184; SKOT, Danish abbreviation of small childrens diet and well-being) with a cohort consisting mainly of nonobese mothers (SKOT I, n=329).Subjects/Methods:Dietary intake was assessed by 7-day records, and dietary patterns were identified by principal component analysis.Results:SKOT I was characterized by a lower maternal body mass index (BMI) and a higher social class than SKOT II in relation to parental education and occupation. Infants in SKOT II had lower scores on a Health-Conscious Food pattern reflected at the food group level, for example, with lower intake of the food groups Fruit and Vegetable but higher intake of WheatBreadNoWholegrain in SKOT II compared with SKOT I. Moreover, SKOT II had shorter durations of breastfeeding, earlier introductions of complementary feeding, higher energy intake from protein but lower energy intakes from monounsaturated fatty acids and polyunsaturated fatty acids at 9 months. SKOT II had higher weight-for-age and length-for-age z-scores, but no differences in BMI z-scores, as compared with SKOT I at 9 months.Conclusions:Infants of obese mothers from a lower social class seem to have a less healthy diet and higher weight and length z-scores at 9 months. Therefore, the promotion of healthy complementary feeding might be beneficial for the prevention of health implications, such as obesity, later in life for these infants.

A likelihood based estimating equation for the Clayton-Oakes model with marginal proportional hazards

Multivariate failure time data arise when data consist of clusters in which the failure times may be dependent. A popular approach to such data is the marginal proportional hazards model with estimation under the working independence assumption. In this paper, we consider the Clayton-Oakes model with marginal proportional hazards and use the full model structure to improve on efficiency compared with the independence analysis. We derive a likelihood based estimating equation for the regression parameters as well as for the correlation parameter of the model. We give the large sample properties of the estimators arising from this estimating equation. Finally, we investigate the small sample properties of the estimators through Monte Carlo simulations. Copyright 2003 Board of the Foundation of the Scandinavian Journal of Statistics..

Evaluation of multi‐outcome longitudinal studies

Evaluation of intervention effects on multiple outcomes is a common scenario in clinical studies. In longitudinal studies, such evaluation is a challenge if one wishes to adequately capture simultaneous data behavior. In this situation, a common approach is to analyze each outcome separately. As a result, multiple statistical statements describing the intervention effect need to be reported and an adjustment for multiple testing is necessary. This is typically done by means of the Bonferroni procedure, which does not take into account the correlation between outcomes, thus resulting in overly conservative conclusions. We propose an alternative approach for multiplicity adjustment that incorporates dependence between outcomes, resulting in an appreciably less conservative evaluation. The ability of the proposed method to control the familywise error rate is evaluated in a simulation study, and the applicability of the method is demonstrated in two examples from the literature.

GLOBAL PATTERNS OF LEPTOSPIRA PREVALENCE IN VERTEBRATE RESERVOIR HOSTS

Abstract Leptospirosis is a widespread emerging bacterial zoonosis. As the transmission is believed to be predominantly waterborne, human incidence is expected to increase in conjunction with global climate change and associated extreme weather events. Providing more accurate predictions of human leptospirosis requires more detailed information on animal reservoirs that are the source of human infection. We evaluated the prevalence of Leptospira in vertebrates worldwide and its association with taxonomy, geographic region, host biology, ambient temperature, and precipitation patterns. A multivariate regression analysis with a meta-analysis-like approach was used to analyze compiled data extracted from 300 Leptospira-related peer reviewed papers. A fairly uniform Leptospira infection prevalence of about 15% was found in the majority of mammalian families. Higher prevalence was frequently associated with species occupying urban habitats, and this may explain why climatic factors were not significantly correlated with prevalence as consistently as expected. Across different approaches of the multiple regression analyses, the variables most frequently correlated with Leptospira infection prevalence were the hosts ability to swim, minimum ambient temperature, and methodologic quality of the study. Prevalence in carnivores was not associated with any climatic variable, and the importance of environmental risk factors were indicated to be of lesser consequence in nonhuman mammals. The dataset is made available for further analysis.