Emergence of the natural history of Myhre syndrome: 47 patients evaluated in the Massachusetts General Hospital Myhre Syndrome Clinic (2016-2023)

Myhre syndrome is an increasingly diagnosed ultrarare condition caused by recurrent germline autosomal dominant de novo variants in SMAD4. Detailed multispecialty evaluations performed at the Massachusetts General Hospital (MGH) Myhre Syndrome Clinic (2016-2023) and by collaborating specialists have facilitated deep phenotyping, genotyping and natural history analysis. Of 47 patients (four previously reported), most (81%) patients returned to MGH at least once. For patients followed for at least 5 years, symptom progression was observed in all. 55% were female and 9% were older than 18 years at diagnosis. Pathogenic variants in SMAD4 involved protein residues p.Ile500Val (49%), p.Ile500Thr (11%), p.Ile500Leu (2%), and p.Arg496Cys (38%). Individuals with the SMAD4 variant p.Arg496Cys were less likely to have hearing loss, growth restriction, and aortic hypoplasia than the other variant groups. Those with the p.Ile500Thr variant had moderate/severe aortic hypoplasia in three patients (60%), however, the small number (n = 5) prevented statistical comparison with the other variants. Two deaths reported in this cohort involved complex cardiovascular disease and airway stenosis, respectively. We provide a foundation for ongoing natural history studies and emphasize the need for evidence-based guidelines in anticipation of disease-specific therapies.

The effect of activity and face masks on exhaled particles in children

Importance

Despite the high burden of respiratory infections among children, the production of exhaled particles during common activities and the efficacy of face masks in children have not been sufficiently studied.

Objective

To determine the effect of type of activity and mask usage on exhaled particle production in children.

Methods

Healthy children were asked to perform activities that ranged in intensity (breathing quietly, speaking, singing, coughing, and sneezing) while wearing no mask, a cloth mask, or a surgical mask. The concentration and size of exhaled particles were assessed during each activity.

Results

Twenty-three children were enrolled in the study. Average exhaled particle concentration increased by intensity of activity, with the lowest particle concentration during tidal breathing (1.285 particles/cm3 [95% CI 0.943, 1.627]) and highest particle concentration during sneezing (5.183 particles/cm3 [95% CI 1.911, 8.455]). High-intensity activities were associated with an increase primarily in the respirable size (≤ 5 µm) particle fraction. Surgical and cloth masks were associated with lower average particle concentration compared to no mask (P = 0.026 for sneezing). Surgical masks outperformed cloth masks across all activities, especially within the respirable size fraction. In a multivariable linear regression model, we observed significant effect modification of activity by age and by mask type.

Interpretation

Similar to adults, children produce exhaled particles that vary in size and concentration across a range of activities. Production of respirable size fraction particles (≤ 5 µm), the dominant mode of transmission of many respiratory viruses, increases significantly with coughing and sneezing and is most effectively reduced by wearing surgical face masks.

Pemphigoid of the pulmonary system (POPS): A review of a less recognized feature

This review of Pemphigoid of the Pulmonary System (POPS) is a comprehensive description of pulmonary involvement in patients with mucous membrane pemphigoid (MMP), which is an orphan autoimmune blistering disease. The objective of the review was to analyze clinical features of pulmonary involvement in MMP. This POPS review is a case series in which multiple search engines were utilized from inception to June 2022 for cases of MMP with biopsy and immunopathology proven tracheal and bronchial pemphigoid. Clinical profiles prior to pulmonary involvement, bronchoscopy findings, clinical course and therapy were recorded and cause of death was analyzed. Patients with documented MMP who developed tracheal, bronchial and pulmonary involvement were included in the POPS review. Histology and immunopathology documentation were essential diagnostic criteria. Comparison groups were not possible. Patients were treated with immunosuppressive therapy. Some required surgical interventions. Six of the 11 patients attained complete or partial remission on or off therapy. Five patients died from pulmonary complications. The POPS review had six females and five males. The mean age at onset was 20 years (range 4-76), while 80% of the patients were under 40 years. All had severe widespread MMP involving three to five mucosal tissues. 100% had oral, 82% had ocular and cutaneous involvement. Pulmonary involvement occurred at 24 mo (range 2-372) after the onset of MMP. Bronchoscopy revealed acute inflammation during active disease and scarring of the trachea and bronchi in the later stages. Systemic infections occurred in 45%, while pulmonary infection occurred in 36%. Mortality due to respiratory failure, at the median age of 20 years (range 18-76), occurred in 45% of the patients, and was considered disease related. In spite of the young age, while there are some similarities in the clinical profile and response to systemic therapy, there are definitive differences from other patients with MMP. Early diagnosis with appropriate management could produce better clinical outcomes and prevent mortality in this orphan disease. Consequently, there is a critical need for early identification and diagnosis of POPS.

Effect modification by age of the association between obstructive lung diseases, smoking, and COVID-19 severity

Introduction

Obstructive lung diseases (asthma and chronic obstructive pulmonary disease (COPD)) and smoking are associated with greater risk of respiratory infections and hospitalisations, but conflicting data exist regarding their association with severity of COVID-19, and few studies have evaluated whether these associations differ by age.

Objectives

To examine the associations between asthma, COPD and smoking on the severity of COVID-19 among a cohort of hospitalised patients, and to test for effect modification by age.

Methods

We performed a retrospective analysis of electronic health record data of patients admitted to Massachusetts General Hospital, assigning the maximal WHO Clinical Progression Scale score for each patient during the first 28 days following hospital admission. Using ordered logistic regression, we measured the association between maximal severity score and asthma, COPD and smoking and their interaction with age.

Measurements and main results

Among 1391 patients hospitalised with COVID-19, we found an increased risk of severe disease among patients with COPD and prior smoking, independent of age. We also found evidence of effect modification by age with asthma and current smoking; in particular, asthma was associated with decreased COVID-19 severity among older adults, and current smoking was associated with decreased severity among younger patients.

Conclusions

This cohort study identifies age as a modifying factor for the association between asthma and smoking on severity of COVID-19. Our findings highlight the complexities of determining risk factors for COVID-19 severity, and suggest that the effect of risk factors may vary across the age spectrum.

Virologic features of SARS-CoV-2 infection in children

BACKGROUND

Data on pediatric COVID-19 has lagged behind adults throughout the pandemic. An understanding of SARS-CoV-2 viral dynamics in children would enable data-driven public health guidance.

METHODS

Respiratory swabs were collected from children with COVID-19. Viral load was quantified by RT-PCR; viral culture was assessed by direct observation of cytopathic effects and semiquantitative viral titers. Correlations with age, symptom duration, and disease severity were analyzed. SARS-CoV-2 whole genome sequences were compared with contemporaneous sequences.

RESULTS

110 children with COVID-19 (median age 10 years, range 2 weeks-21 years) were included in this study. Age did not impact SARS-CoV-2 viral load. Children were most infectious within the first five days of illness, and severe disease did not correlate with increased viral loads. Pediatric SARS-CoV-2 sequences were representative of those in the community and novel variants were identified.

CONCLUSIONS

Symptomatic and asymptomatic children can carry high quantities of live, replicating SARS-CoV-2, creating a potential reservoir for transmission and evolution of genetic variants. As guidance around social distancing and masking evolves following vaccine uptake in older populations, a clear understanding of SARS-CoV-2 infection dynamics in children is critical for rational development of public health policies and vaccination strategies to mitigate the impact of COVID-19.

Virologic features of SARS-CoV-2 infection in children

BACKGROUND

Data on pediatric COVID-19 has lagged behind adults throughout the pandemic. An understanding of SARS-CoV-2 viral dynamics in children would enable data-driven public health guidance.

METHODS

Respiratory swabs were collected from children with COVID-19. Viral load was quantified by RT-PCR; viral culture was assessed by direct observation of cytopathic effects and semiquantitative viral titers. Correlations with age, symptom duration, and disease severity were analyzed. SARS-CoV-2 whole genome sequences were compared with contemporaneous sequences.

RESULTS

110 children with COVID-19 (median age 10 years, range 2 weeks-21 years) were included in this study. Age did not impact SARS-CoV-2 viral load. Children were most infectious within the first five days of illness, and severe disease did not correlate with increased viral loads. Pediatric SARS-CoV-2 sequences were representative of those in the community and novel variants were identified.

CONCLUSIONS

Symptomatic and asymptomatic children can carry high quantities of live, replicating SARS-CoV-2, creating a potential reservoir for transmission and evolution of genetic variants. As guidance around social distancing and masking evolves following vaccine uptake in older populations, a clear understanding of SARS-CoV-2 infection dynamics in children is critical for rational development of public health policies and vaccination strategies to mitigate the impact of COVID-19.

Aerosol transmission of SARS-CoV-2 by children and adults during the COVID-19 pandemic

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can be transmitted via respiratory droplets, aerosols, and to a lesser extent, fomites. Defining the factors driving infectivity and transmission is critical for infection control and containment of this pandemic. We outline the major methods of transmission of SARS-CoV-2, focusing on aerosol transmission. We review principles of aerosol science and discuss their implications for mitigating the spread of SARS-CoV-2 among children and adults.

The diagnosis of respiratory disease in children using a phone-based cough and symptom analysis algorithm: The smartphone recordings of cough sounds 2 (SMARTCOUGH-C 2) trial design

The diagnosis of acute respiratory diseases in children can be challenging, and no single objective diagnostic test exists for common pediatric respiratory diseases. Previous research has demonstrated that ResAppDx, a cough sound and symptom-based analysis algorithm, can identify common respiratory diseases at the point of care. We present the study protocol for SMARTCOUGH-C 2, a prospective diagnostic accuracy trial of a cough and symptom-based algorithm in a cohort of children presenting with acute respiratory diseases. The objective of the study is to assess the performance characteristics of the ResAppDx algorithm in the diagnosis of common pediatric acute respiratory diseases.

Insight into the pediatric and adult dichotomy of COVID-19: Age-related differences in the immune response to SARS-CoV-2 infection

The difference in morbidity and mortality between adult and pediatric coronavirus disease 2019 infections is dramatic. Understanding pediatric-specific acute and delayed immune responses to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is critical for the development of vaccination strategies, immune-targeted therapies, and treatment and prevention of multisystem inflammatory syndrome in children. The goal of this review is to highlight research developments in the understanding of the immune responses to SARS-CoV-2 infections, with a specific focus on age-related immune responses.

The future is here: Integrating genetics into the pediatric pulmonary clinic

Recognition of underlying genetic etiologies of disease is increasing at an exponential rate, likely due to greater access to and lower cost of genetic testing. Monogenic causes of disease, or conditions resulting from a mutation or mutations in a single gene, are now well recognized in every subspecialty, including pediatric pulmonary medicine; thus, it is important to consider genetic conditions when evaluating children with respiratory disease. In the pediatric pulmonary clinic, genetic testing should be considered when multiple family members present with similar or related clinical features and when individuals have unusual clinical presentations, such as early-onset disease or complex, syndromic features. This review provides a practical guide for genetic diagnosis in the pediatric pulmonary setting, including a review of genetic concepts, considerations for test selection and results in interpretation, as well as an overview of genetic differential diagnoses for common pediatric pulmonary phenotypes. Genetic conditions that commonly present to the pediatric pulmonary clinic are reviewed in a companion article by Yonker et al.

Recognizing genetic disease: A key aspect of pediatric pulmonary care

Advancement in technology has improved recognition of genetic etiologies of disease, which has impacted diagnosis and management of rare disease patients in the pediatric pulmonary clinic. This review provides an overview of genetic conditions that are likely to present with pulmonary features and require extensive care by the pediatric pulmonologist. Increased familiarity with these conditions allows for improved care of these patients by reducing time to diagnosis, tailoring management, and prompting further investigation into these disorders.

The Unexpected Risks of COVID-19 on Asthma Control in Children

Much is being learned about clinical outcomes for adult COVID-19 patients with underlying chronic conditions; however, there is less coverage on how the COVID-19 pandemic impacts the management of chronic medical conditions, such as asthma, in children and youth. Asthma is a common chronic medical condition in children that is uniquely susceptible to changes brought on by COVID-19. Sudden dramatic changes in the environment, medical practice, and medication use have altered the asthma management landscape with potential impacts on asthma outcomes. In this paper, we review how changes in transportation and travel patterns, school attendance, physical activity, and time spent indoors, along with changes in health care delivery since the start of the pandemic, all play a contributing role in asthma control in children. We review potentially important influences of asthma control in children during the COVID-19 pandemic worthy of further study.

Lung transplant referral practice patterns: a survey of cystic fibrosis physicians and general pulmonologists

BACKGROUND

Many individuals with cystic fibrosis (CF) die from respiratory failure without referral for lung transplant. Physician practices that may expedite, delay, or preclude referral, are poorly understood.

METHODS

Two parallel, web-based surveys focusing on lung transplant referral triggers and barriers, as well as pre-referral evaluation, were emailed to pulmonologists practicing in the New England region. One questionnaire was sent to CF providers (n = 61), and the second to general pulmonary providers practicing at the same institutions (n = 61).

RESULTS

There were 43 (70%) responses to the CF provider survey, and 25 (41%) responses to the general pulmonary ('non-CF') provider survey. Primary reasons for CF providers to refer their patients included: rapidly declining lung function (91%) and a forced expiratory volume in 1 s (FEV₁) below 30% predicted (74%). The greatest barriers to referral for both CF and non-CF providers included active tobacco use (65 and 96%, respectively, would not refer), and active alcohol or other substance use or dependence (63 and 80%). Furthermore, up to 42% of CF providers would potentially delay their referral if triple-combination therapy or other promising new, disease-specific therapy were anticipated. In general, non-CF providers perform a more robust pre-referral medical work-up, while CF providers complete a psychosocial evaluation in higher numbers. Across both groups, communication with lung transplant programs was reported to be inadequate.

CONCLUSIONS

Physician-level barriers to timely lung transplant referral exist and need to be addressed. Enhanced communication between lung transplant programs and pulmonary providers may reduce these barriers.

Eteplirsen Treatment Attenuates Respiratory Decline in Ambulatory and Non-Ambulatory Patients with Duchenne Muscular Dystrophy

BACKGROUND

Duchenne muscular dystrophy (DMD) patients experience skeletal muscle degeneration, including respiratory muscles. Respiratory decline in glucocorticoid-treated DMD patients, measured by percent predicted forced vital capacity (FVC% p), is typically 5% annually in patients aged 10 to 18 years.

OBJECTIVE

Evaluate the effects of eteplirsen on FVC% p annual change in 3 trials versus matched Cooperative International Neuromuscular Research Group Duchenne Natural History Study (CINRG DNHS) controls.

METHODS

Eteplirsen studies 201/202 evaluated eligible ambulatory DMD patients for at least 4 years, study 204 evaluated primarily non-ambulatory DMD patients for 2 years, and ongoing study 301 is evaluating ambulatory DMD patients for 2 years (interim analysis is included). Eteplirsen-treated patients (n = 74) were amenable to exon 51 skipping and were receiving glucocorticoids. Three CINRG DNHS cohorts included: glucocorticoid-treated patients amenable to exon 51 skipping (Exon 51 CINRG DNHS; n = 20), all glucocorticoid-treated CINRG patients (All CINRG DNHS; n = 172), and all glucocorticoid-treated genotyped CINRG DNHS patients (Genotyped CINRG DNHS; n = 148). FVC% p assessments between ages 10 and <18 years were included for all patients; mixed-model analyses characterized FVC% p annual change.

RESULTS

FVC% p annual change was greater for CINRG DNHS Exon 51 controls (- 6.00) versus patients in studies 201/202, study 204, and study 301 (- 2.19, P < 0.001; - 3.66, P 0.004; and - 3.79, P 0.017, respectively). FVC% p annual change in all eteplirsen studies suggested treatment benefit compared with the Genotyped CINRG DNHS (- 5.67) and All CINRG DNHS (- 5.56) cohorts (P < 0.05, all comparisons).

CONCLUSIONS

Significant, clinically meaningful attenuation of FVC%p decline was observed in eteplirsen-treated patients versus CINRG DNHS controls.

Using Physician-Level Emergency Department Utilization Reports to Address Avoidable Visits by Patients Managed by Pediatric Specialists

OBJECTIVES

Emergency department (ED) utilization is a major driver of cost. Specialist physicians have an important role in addressing ED utilization, especially at tertiary medical centers that treat highly specialized patients. We analyzed if reporting of ED utilization to pediatric specialist physicians can decrease ED visits.

METHODS

Physicians within pediatric neurology, hematology and oncology, infectious diseases, and pulmonary divisions received their ED use reports. By using control charts, we examined if this intervention decreased the rate of ED utilization.

RESULTS

Overall, for the 4 divisions, specialty-related ED utilization decreased significantly during all hours, weekdays, and office hours. This was in the setting of ED utilization increasing for all diagnoses ED visits. Pediatric ED volume did not change during the study period.

CONCLUSIONS

Physician-level reporting of ED utilization was associated with a reduction in ED use by patients managed by our pediatric specialists.

Diagnostic and clinical course of pulmonary interstitial glycogenosis: The tip of the iceberg

"Pulmonary Interstitial Glycogenosis: Diagnostic Evaluation and Clinical Course," written by Liptzin et al is a timely and insightful phenotypic summary of a rare pediatric interstitial lung disease. Twenty-four infants with biopsy-proven pulmonary interstitial glycogenosis (PIG) were reviewed at their center. Genetic analysis, bronchoscopy results, imaging, biopsy, and cardiology findings were described, and treatment decision and clinical outcomes were discussed.

Long-Term Pulmonary Function in Duchenne Muscular Dystrophy: Comparison of Eteplirsen-Treated Patients to Natural History

Background:

Duchenne muscular dystrophy (DMD) is a rare, degenerative, X-linked genetic disease that results in progressive muscle loss and premature death, most commonly from respiratory or cardiac failure. DMD is primarily caused by whole exon deletions, resulting in a shift of the dystrophin mRNA reading frame that prevents production of functional dystrophin protein. Eteplirsen, a phosphorodiamidate morpholino oligomer (PMO), is designed to skip exon 51, restore the reading frame, and induce production of internally shortened dystrophin in patients with mutations amenable to such treatment.

Objective:

Describe lung function assessed throughout eteplirsen studies 201/202.

Methods:

Studies 201/202 included 12 patients treated with eteplirsen over 5 years. Pulmonary function tests included forced vital capacity (FVC), maximum expiratory pressure (MEP), and maximum inspiratory pressure (MIP). With no long-term placebo control, FVC results were compared with data from the United Dystrophinopathy Project (UDP). MIP and MEP were compared to published natural history.

Results:

Age-adjusted mixed-model repeated-measures analysis showed decreases of 2.3% and 2.6% annually for FVC% p and MEP% p, and an annual increase of 0.6% for MIP% p for the eteplirsen-treated cohort. Data from the UDP demonstrated a 4.1% decline in FVC% p. The published natural history reports annual declines of at least 2.7% and 3.8% for MEP% p and MIP% p, respectively, in patients with DMD.

Conclusions:

With eteplirsen treatment, deterioration of respiratory muscle function based on FVC% p was half of that seen in the UDP; MEP% p and MIP% p compared favorably with natural history.

"Friending" teens: systematic review of social media in adolescent and young adult health care

Background

Social media has emerged as a potentially powerful medium for communication with adolescents and young adults around their health choices.

Objective

The goal of this systematic review is to identify research on the use of social media for interacting with adolescents and young adults in order to achieve positive health outcomes.

Methods

A MEDLINE/PubMed electronic database search was performed between January 1, 2002 and October 1, 2013, using terms to identify peer-reviewed research in which social media and other Web 2.0 technologies were an important feature. We used a systematic approach to retrieve papers and extract relevant data.

Results

We identified 288 studies involving social media, of which 87 met criteria for inclusion; 75 studies were purely observational and 12 were interventional. The ways in which social media was leveraged by these studies included (1) observing adolescent and young adult behavior (n=77), (2) providing health information (n=13), (3) engaging the adolescent and young adult community (n=17), and (4) recruiting research participants (n=23). Common health topics addressed included high-risk sexual behaviors (n=23), alcohol, tobacco, and other drug use (n=19), Internet safety (n=8), mental health issues (n=18), medical conditions (n=11), or other specified issues (n=12). Several studies used more than one social media platform and addressed more than one health-related topic.

Conclusions

Social media technologies offer an exciting new means for engaging and communicating with adolescents and young adults; it has been successfully used to engage this age group, identify behaviors, and provide appropriate intervention and education. Nevertheless, the majority of studies to date have been preliminary and limited in their methodologies, and mostly center around evaluating how adolescents and young adults use social media and the resulting implications on their health. Although these explorations are essential, further exploration and development of these strategies into building effective interventions is necessary.

Coenzyme Q10 and immunity: A case report and new implications for treatment of recurrent infections in metabolic diseases

Coenzyme Q10 (CoQ10) deficiency can manifest diversely, from isolated myopathy to multisystem involvement. Immune dysregulation has not been reported as a feature of the disease. We report a four-year old girl with failure to thrive, recurrent infections, developmental delay with hypotonia, and CoQ10 deficiency with impaired immune function, which improved after CoQ10 and immunoglobulin replacement therapy. Immune dysfunction in CoQ10 deficiency should be considered and treated appropriately.

Recombinant human mannose-binding lectin dampens human alveolar macrophage inflammatory responses to influenza A virus in vitro

IAV pneumonia remains a serious global health problem, and preventative and therapeutic strategies remain limited. AM are critical effector cells in the control of influenza, impairing IAV replication, promoting IAV clearance, and promoting efferocytosis and resolution of lung inflammation. MBL, an innate immune pattern recognition molecule, present in the lungs, binds IAV, and plasma MBL deficiency is associated with increased susceptibility to IAV, although the mechanism remains incompletely understood, and the influence of MBL on the IAV-AM interaction has not been established. In the current study, focusing on human macrophages (U937 cell line and clinically relevant human AM), data demonstrated that unopsonized IAV is readily internalized, induced release of TNF and ROS, and promoted macrophage apoptosis. In contrast, IAV, opsonized with rhMBL, reduced IAV uptake and macrophage apoptosis and dramatically reduced TNF release and ROS. Macrophage host-defense responses were reduced further in the presence of MASPs. Taken together, these data support the concept that rhMBL may serve a protective innate host response and a critical biological response modifier function by limiting AM inflammation, oxidative injury, and AM apoptosis, which may allow effective IAV clearance while limiting collateral damage to vital organs, such as the lungs.

Endothelial expression of guidance cues in vessel wall homeostasis dysregulation under proatherosclerotic conditions

OBJECTIVE

Emerging evidence suggests that neuronal guidance cues, typically expressed during development, are involved in both physiological and pathological immune responses. We hypothesized that endothelial expression of such guidance cues may regulate leukocyte trafficking into the vascular wall during atherogenesis.

APPROACH AND RESULTS

We demonstrate that members of the netrin, semaphorin, and ephrin family of guidance molecules are differentially regulated under conditions that promote or protect from atherosclerosis. Netrin-1 and semaphorin3A are expressed by coronary artery endothelial cells and potently inhibit chemokine-directed migration of human monocytes. Endothelial expression of these negative guidance cues is downregulated by proatherogenic factors, including oscillatory shear stress and proinflammatory cytokines associated with monocyte entry into the vessel wall. Furthermore, we show using intravital microscopy that inhibition of netrin-1 or semaphorin3A using blocking peptides increases leukocyte adhesion to the endothelium. Unlike netrin-1 and semaphorin3A, the guidance cue ephrinB2 is upregulated under proatherosclerotic flow conditions and functions as a chemoattractant, increasing leukocyte migration in the absence of additional chemokines.

CONCLUSIONS

The concurrent regulation of negative and positive guidance cues may facilitate leukocyte infiltration of the endothelium through a balance between chemoattraction and chemorepulsion. These data indicate a previously unappreciated role for axonal guidance cues in maintaining the endothelial barrier and regulating leukocyte trafficking during atherogenesis.

Relationship between sleep apnea, fat distribution, and insulin resistance in obese children

BACKGROUND

Obstructive sleep apnea (OSA) is associated with obesity, inflammation, and insulin resistance. The role of fat distribution in OSA pathogenesis has not been established in children. The objective of the study is to examine the relationship between fat distribution, OSA, and insulin resistance in an unselected population of obese children.

METHODS

All obese (BMI > 95th percentile) children (ages 5-18 y) seen at a pediatric obesity clinic were invited to participate. Subjects underwent polysomnography, and were tested for dyslipidemia, inflammation, and insulin resistance measured by the homeostasis model assessment (HOMA). In a subset of subjects, magnetic resonance (MRI) imaging was used to determine the abdominal visceral and subcutaneous adipose tissue areas and magnetic resonance spectroscopy (MRS) spectroscopy was used to intramyocellular lipids in leg muscles.

MEASUREMENTS AND MAIN RESULTS

31 obese subjects enrolled and completed polysomnography and serum testing, and 19 subjects underwent MRI/MRS. The mean age was 12.6 ± 3.0 y and the mean body mass index (BMI) was 39.5 ± 11.2 kg/m(2). Forty-eight percent had OSA (mean apnea hypopnea index [AHI] 6.26 ± 6.77 events/h) Subjects with OSA had significantly increased BMI, log HOMA, triglycerides, and leptin compared to those without OSA. In regression analysis, only BMI z-score was associated with log HOMA. In the subset of patients with imaging data, visceral fat area was strongly predictive of AHI (p = 0.003, r(2) = 0.556). BMI z-score, gender, and age were not predictive.

CONCLUSIONS

Visceral fat distribution is independently predictive of OSA severity in obese children.

Initial experience using propranolol as an adjunctive treatment in children with aggressive recurrent respiratory papillomatosis

We performed a retrospective chart review with a 6-month follow-up to examine the initial use of propranolol as an adjunctive treatment in children with severe recurrent respiratory papillomatosis. This is the first such report. Two of 3 children with severe recurrent respiratory papillomatosis demonstrated a response to oral propranolol therapy, as evidenced by an improved voice and by an increased time between surgical interventions. One child demonstrated no response to propranolol, and medication was halted. Both children who demonstrated a response had undergone more than 10 surgical interventions in the previous year, along with prior treatment including surgical excision and adjuvant therapy. Both children more than doubled the interval between treatments after propranolol administration, and the parents of both children noted marked improvement of the child's voice as measured by their Pediatric Voice-Related Quality of Life score (from 40 to 67.5 in one child and from 27 to 60 in the other child). No child experienced hypoglycemia or blood pressure abnormalities. We conclude that initial use of propranolol as an adjunctive measure in severe recurrent respiratory papillomatosis shows it to have some efficacy in delaying surgical intervention and improving voice. Previous reports have demonstrated relatively safe use of propranolol in children with hemangiomas. Further studies are needed to determine the long-term effectiveness, dosing strategies, and side-effect profile of propranolol for treatment of recurrent respiratory papillomatosis.

Nitrofen induces apoptosis independently of retinaldehyde dehydrogenase (RALDH) inhibition

BACKGROUND

Nitrofen is a diphenyl ether that induces congenital diaphragmatic hernia (CDH) in rodents. Its mechanism of action has been hypothesized as inhibition of the retinaldehyde dehydrogenase (RALDH) enzymes with consequent reduced retinoic acid signaling.

METHODS

To determine if nitrofen inhibits RALDH enzymes, a reporter gene construct containing a retinoic acid response-element (RARE) was transfected into HEK-293 cells and treated with varying concentrations of nitrofen in the presence of retinaldehyde (retinal). Cell death was characterized by caspace-cleavage microplate assays and terminal deoxynucleotidyl transferase dUTP nick end-labeling (TUNEL) assays. Ex vivo analyses of cell viability were characterized in fetal rat lung explants using Live/Dead staining. Cell proliferation and apoptosis were assessed using fluorescent immunohistochemistry with phosphorylated histone and activated caspase antibodies on explant tissues. Nile red staining was used to identify intracellular lipid droplets.

RESULTS

Nitrofen-induced dose-dependent declines in RARE-reporter gene expression. However, similar reductions were observed in control-reporter constructs suggesting that nitrofen compromised cell viability. These observed declines in cell viability resulted from increased cell death and were confirmed using two independent assays. Ex vivo analyses showed that mesenchymal cells were particularly susceptible to nitrofen-induced apoptosis while epithelial cell proliferation was dramatically reduced in fetal rat lung explants. Nitrofen treatment of these explants also showed profound lipid redistribution, primarily to phagocytes.

CONCLUSIONS

The observed declines in nitrofen-associated retinoic acid signaling appear to be independent of RALDH inhibition and likely result from nitrofen induced cell death/apoptosis. These results support a cellular apoptotic mechanism of CDH development, independent of RALDH inhibition.

A novel L-ficolin/mannose-binding lectin chimeric molecule with enhanced activity against Ebola virus

Ebola viruses constitute a newly emerging public threat because they cause rapidly fatal hemorrhagic fevers for which no treatment exists, and they can be manipulated as bioweapons. We targeted conserved N-glycosylated carbohydrate ligands on viral envelope surfaces using novel immune therapies. Mannose-binding lectin (MBL) and L-ficolin (L-FCN) were selected because they function as opsonins and activate complement. Given that MBL has a complex quaternary structure unsuitable for large scale cost-effective production, we sought to develop a less complex chimeric fusion protein with similar ligand recognition and enhanced effector functions. We tested recombinant human MBL and three L-FCN/MBL variants that contained the MBL carbohydrate recognition domain and varying lengths of the L-FCN collagenous domain. Non-reduced chimeric proteins formed predominantly nona- and dodecameric oligomers, whereas recombinant human MBL formed octadecameric and larger oligomers. Surface plasmon resonance revealed that L-FCN/MBL76 had the highest binding affinities for N-acetylglucosamine-bovine serum albumin and mannan. The same chimeric protein displayed superior complement C4 cleavage and binding to calreticulin (cC1qR), a putative receptor for MBL. L-FCN/MBL76 reduced infection by wild type Ebola virus Zaire significantly greater than the other molecules. Tapping mode atomic force microscopy revealed that L-FCN/MBL76 was significantly less tall than the other molecules despite similar polypeptide lengths. We propose that alterations in the quaternary structure of L-FCN/MBL76 resulted in greater flexibility in the collagenous or neck region. Similarly, a more pliable molecule might enhance cooperativity between the carbohydrate recognition domains and their cognate ligands, complement activation, and calreticulin binding dynamics. L-FCN/MBL chimeric proteins should be considered as potential novel therapeutics.

A comparison of respiratory patterns in healthy term infants placed in car safety seats and beds

OBJECTIVE

The purpose of this work was to compare the incidence of apnea, hypopnea, bradycardia, or oxygen desaturation in healthy term newborns placed in hospital cribs, infant car safety beds, or infant car safety seats.

METHODS

A consecutive series of 200 newborns was recruited on the second day of life. Each subject was studied while placed in the hospital crib (30 minutes), car bed (60 minutes), and car seat (60 minutes). Physiologic data, including oxygen saturation, frequency, and type of apnea, hypopnea, and bradycardia were obtained and analyzed in a blinded manner.

RESULTS

The mean oxygen saturation level was significantly different among all of the positions (97.9% for the hospital crib, 96.3% for the car bed, and 95.7% for the car seat; P < .001). The mean minimal oxygen saturation level was lower while in both safety devices (83.7% for the car bed and 83.6% for the car seat) compared with in the hospital crib (87.4%) (P < .001). The mean total time spent with an oxygen saturation level of <95% was significantly higher (P = .003) in both safety devices (car seat: 23.9%; car bed: 17.2%) when compared with the hospital crib (6.5%). A second study of 50 subjects in which each infant was placed in each position for 120 minutes yielded similar results.

CONCLUSIONS

In healthy term newborns, significant desaturations were observed in both car beds and car seats as compared with hospital cribs. This study was limited by lack of documentation of sleep stage. Therefore, these safety devices should only be used for protection during travel and not as replacements for cribs.

Travel patterns to school among children with asthma

BACKGROUND

Active commuting to school provides regular exercise, which can improve asthma symptoms. Little is known about how children with asthma travel to school.

OBJECTIVE

To identify travel patterns and parental perceptions surrounding mode of travel to school among children with asthma.

METHODS

Cross-sectional study of 176 children with asthma aged 5 to 15 years. Parents completed questionnaires assessing mode of travel to school, physical activity, asthma control, physician counseling, and factors influencing parental decisions. Data analysis included descriptive and bivariate statistics.

RESULTS

Few (16%) children with asthma actively commute to school. Active travelers lived closer to school, and "distance" was the most frequently reported factor influencing a parent's decision regarding travel mode to school. Parents reported few concerns about pollution and little physician counseling on active travel.

CONCLUSION

Few children with asthma actively travel to school. Asthma-specific concerns do not appear to guide parental decisions on travel mode to school.

Retinoic acid-mediated differentiation protects against nitrofen-induced apoptosis

BACKGROUND

Nitrofen is a diphenyl ether that induces a spectrum of birth defects subsequent to administration to pregnant rodents, in which the molecular etiology of these defects are poorly characterized. Because previous reports showed that nitrofen induced apoptosis in undifferentiated P19 teratocarcinoma cells, we hypothesized that undifferentiated fetal cells have greater susceptibility to nitrofen-induced apoptosis than their differentiated derivatives.

METHODS

To investigate this hypothesis, cell lines including P19 and F9 were differentiated with retinoic acid into neuronal and endodermal derivatives respectively. Apoptosis was characterized by caspase-3 cleavage and Terminal transferase dUTP nick end labeling (TUNEL) assays.

RESULTS

Both differentiated cell-types had reduced nitrofen-induced caspase-3 cleavage and DNA fragmentation compared with the naive controls, strongly suggesting that differentiation of these cells protects against nitrofen-induced apoptosis. In addition, resistance to apoptotic induction was proportional to the expression levels of the differentiation marker, p27 (kip1) while direct proportionality was not observed for the antiapoptotic protein Bcl-2.

CONCLUSIONS

These studies show that nitrofen may induce its associated birth defects via a mechanism involving apoptosis of undifferentiated fetal cells.

Lung development and implications for hypoplasia found in congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is associated with various degrees of pulmonary hypoplasia and severe persistent pulmonary hypertension in the newborn. These conditions have significant implications for the outcome for the patient. Defects in early lung development are likely to be central to the generation of hypoplasia. A number of mouse models with defects in pathways that are central to lung development were found to have CDH. Understanding all aspects of early lung development will provide fresh insight into the pathogenesis of CDH and its associated conditions.

Comparison of respiratory physiologic features when infants are placed in car safety seats or car beds

OBJECTIVE

The objective of this study was to compare the respiratory physiologic features of healthy term infants placed in either a car bed or a car safety seat.

METHODS

Within the first 1 week of life, 67 healthy term infants were recruited and assigned randomly to be monitored in either a car bed (33 infants) or a car safety seat (34 infants). Physiologic data, including oxygen saturation and frequency and type of apnea, were obtained and analyzed in a blinded manner.

RESULTS

The groups spent similar amounts of time in the devices (car bed: 71.6 minutes; car seat: 74.2 minutes). The mean oxygen saturation values were not different between the groups (car bed: 97.1%; car seat: 97.3%). The percentages of time with oxygen saturation of < 95% were also similar for the 2 groups (car bed: 11.8[corrected]%; car seat: 18.3[corrected]%). In both groups, a number of infants spent high percentages of study time with oxygen saturation of < 95%. The 6 infants with the most time at this level were all in the car safety seat group (54%-63% of study time). Values for the 6 infants in the car bed group with the most time at this level were lower (20%-42%). This difference in the duration of oxygen saturation of < 95% was not statistically significant. The mean end-tidal carbon dioxide levels and the numbers of episodes of apnea were similar for the 2 groups.

CONCLUSIONS

The respiratory physiologic features of infants in the 2 car safety devices were observed to be similar. Of note, substantial periods of time with oxygen saturation of < 95% were surprisingly common in both groups.

Netrin-1 inhibits leukocyte migration in vitro and in vivo

Cell migration plays important roles in embryonic development and inflammation, and this process is highly regulated to ensure tissue homeostasis. A number of barriers exist to prevent the inappropriate migration of leukocytes into healthy peripheral tissues, including retention of these cells in the inactive state and maintenance of the integrity and charge of the vascular endothelium. However, active signals also are likely to exist that can repulse cells or abolish existing cell migration. One such paradigm exists in the developing nervous system, where neuronal migration is mediated by a balance between chemoattractive and chemorepulsive signals. The ability of the guidance molecule netrin-1 to repulse or abolish attraction of neuronal cells expressing the UNC5b receptor makes it an attractive candidate for the regulation of inflammatory cell migration. Here, we show that netrin-1 is expressed on vascular endothelium, where it is regulated by infection and inflammatory cytokines. The netrin-1 receptor UNC5b is strongly expressed by leukocytes, upon which netrin-1 acts as a potent inhibitor of migration to different chemotactic stimuli both in vivo and in vitro. These data suggest that endothelial expression of netrin-1 may inhibit basal cell migration into tissues and that its down-regulation with the onset of sepsis/inflammation may facilitate leukocyte recruitment.