Robin R. Deterding

Molecular identification of bacteria in bronchoalveolar lavage fluid from children with cystic fibrosis.

Culture of bronchoalveolar lavage fluid (BALF) is the gold standard for detection of pathogens in the lower airways in cystic fibrosis (CF). However, current culture results do not explain all clinical observations in CF, including negative culture results during pulmonary exacerbation and inflammation in the absence of pathogens. We hypothesize that organisms not routinely identified by culture occur in the CF airway and may contribute to disease. To test this hypothesis we used a culture-independent molecular approach, based on use of rRNA sequence analysis, to assess the bacterial composition of BALF from children with CF and disease controls (DC). Specimens from 42 subjects (28 CF) were examined, and ≈6,600 total clones were screened to identify 121 species of bacteria. In general, a single rRNA type dominated clone libraries from CF specimens, but not DC. Thirteen CF subjects contained bacteria that are not routinely assessed by culture. In four CF subjects, candidate pathogens were identified and include the anaerobe Prevotella denticola, a Lysobacter sp., and members of the Rickettsiales. The presumptive pathogens Tropheryma whipplei and Granulicatella elegans were identified in cases from the DC group. The presence of unexpected bacteria in CF may explain inflammation without documented pathogens and consequent failure to respond to standard treatment. These results show that molecular techniques provide a broader perspective on airway bacteria than do routine clinical cultures and thus can identify targets for further clinical evaluation.

Future Directions in Idiopathic Pulmonary Fibrosis Research. An NHLBI Workshop Report

The median survival of patients with idiopathic pulmonary fibrosis (IPF) continues to be approximately 3 years from the time of diagnosis, underscoring the lack of effective medical therapies for this disease. In the United States alone, approximately 40,000 patients die of this disease annually. In November 2012, the NHLBI held a workshop aimed at coordinating research efforts and accelerating the development of IPF therapies. Basic, translational, and clinical researchers gathered with representatives from the NHLBI, patient advocacy groups, pharmaceutical companies, and the U.S. Food and Drug Administration to review the current state of IPF research and identify priority areas, opportunities for collaborations, and directions for future research. The workshop was organized into groups that were tasked with assessing and making recommendations to promote progress in one of the following six critical areas of research: (1) biology of alveolar epithelial injury and aberrant repair; (2) role of extracellular matrix; (3) preclinical modeling; (4) role of inflammation and immunity; (5) genetic, epigenetic, and environmental determinants; (6) translation of discoveries into diagnostics and therapeutics. The workshop recommendations provide a basis for directing future research and strategic planning by scientific, professional, and patient communities and the NHLBI.

A comparison of critical thinking in groups of third-year medical students in text, video, and virtual PBL case modalities.

Purpose To determine whether critical thinking in problem-based learning (PBL) group discourse differed according to case modality. Method The study was conducted in 2000 in the Department of Pediatrics at the University of Colorado School of Medicine in Denver. Third-year medical students on their pediatrics clerkship were divided into three groups: face-to-face with a text case, face-to-face with a digital video case, and virtual with a digital video case. Twenty-four groups were divided among the three case modalities. Using an existing coding scheme, each distinct codable unit of discourse was placed into one of 35 indicators reflective of five critical-thinking stages. For each groups discourse, a critical-thinking ratio was calculated for each of the stages. The Kruskal–Wallis test was used to compare the critical-thinking ratios for each stage across the three modalities. Residual conversation to indicate processes occurring within the group was also coded. Results A content analysis of the transcripts of 13 of the 24 group discussions occurred. The virtual groups had the highest critical-thinking ratio. Except for the problem-identification stage, the video groups had higher ratios that the text groups did. Conclusions This exploratory study examined how the mode of case presentation affected the critical thinking of groups using the PBL format. Students who learned in a virtual modality with a digital video case engaged in more critical thinking. The data suggest that the video enhanced critical thinking in both face-to-face and virtual PBL groups.

Neuroendocrine Cell Hyperplasia of Infancy: Diagnosis With High-Resolution CT

OBJECTIVE Neuroendocrine cell hyperplasia of infancy is a form of childhood interstitial lung disease originally reported as persistent tachypnea of infancy. Reports of small series of cases and anecdotal experience have suggested that this disorder may have a consistent CT pattern. The purpose of this study was to review the CT findings in children with neuroendocrine cell hyperplasia of infancy to determine the findings at high-resolution CT, the diagnostic accuracy of CT compared with biopsy, and interrater reliability. MATERIALS AND METHODS Images from 23 CT examinations of children with biopsy-proven neuroendocrine cell hyperplasia of infancy and six CT examinations of children with other childhood interstitial lung diseases were reviewed by two pediatric radiologists with special expertise in thoracic imaging. Identifying digital data were removed, and images were reviewed without clinical data. A CT assessment form was completed for each patient. RESULTS Ground-glass opacification was the most common finding in patients with neuroendocrine cell hyperplasia of infancy. The right middle lobe and lingula were most commonly involved. Air trapping with a mosaic pattern was the second most common finding. Interrater reliability was very good with a kappa value of 0.93. The sensitivity and specificity of CT in the diagnosis of neuroendocrine cell hyperplasia of infancy were at least 78% and 100%. CONCLUSION Neuroendocrine cell hyperplasia of infancy can have a characteristic appearance on high-resolution CT scans, the imaging findings being useful in differentiating neuroendocrine cell hyperplasia of infancy from other types of childhood interstitial lung disease. The appearance aids radiologists in suggesting a specific diagnosis but does not exclude this diagnosis; in 17-22% of cases, the readers in this study did not suggest the diagnosis of neuroendocrine cell hyperplasia of infancy when it was present.

Evaluation of a Diagnostic Approach to Pediatric Interstitial Lung Disease

Objective. To evaluate the value of a systematic approach to the diagnosis of pediatric interstitial lung disease (ILD). Methods. In this descriptive, observational, prospective study, we evaluated 51 children presenting with ILD of unknown etiology during a 3-year period. Specific clinical information regarding history, physical examination, diagnostic evaluation, and final diagnosis was recorded on each patient. Results. A specific diagnosis was established by history and physical examination alone in 1 patient, noninvasive tests alone in 8 others, and invasive tests, including lung biopsy, in another 26. Of the remaining patients, 8 had a suggestivediagnosis, and 8 had no specific diagnosis. Conclusions. A systematic approach to the diagnosis of pediatric ILD is useful, and not all patients need lung biopsy for diagnosis.

Heterogeneous Pulmonary Phenotypes Associated With Mutations in the Thyroid Transcription Factor Gene NKX2-1

BACKGROUND Mutations in the gene encoding thyroid transcription factor, NKX2-1, result in neurologic abnormalities, hypothyroidism, and neonatal respiratory distress syndrome (RDS) that together are known as the brain-thyroid-lung syndrome. To characterize the spectrum of associated pulmonary phenotypes, we identified individuals with mutations in NKX2-1 whose primary manifestation was respiratory disease. METHODS Retrospective and prospective approaches identified infants and children with unexplained diffuse lung disease for NKX2-1 sequencing. Histopathologic results and electron micrographs were assessed, and immunohistochemical analysis for surfactant-associated proteins was performed in a subset of 10 children for whom lung tissue was available. RESULTS We identified 16 individuals with heterozygous missense, nonsense, and frameshift mutations and five individuals with heterozygous, whole-gene deletions of NKX2-1. Neonatal RDS was the presenting pulmonary phenotype in 16 individuals (76%), interstitial lung disease in four (19%), and pulmonary fibrosis in one adult family member. Altogether, 12 individuals (57%) had the full triad of neurologic, thyroid, and respiratory manifestations, but five (24%) had only pulmonary symptoms at the time of presentation. Recurrent respiratory infections were a prominent feature in nine subjects. Lung histopathology demonstrated evidence of disrupted surfactant homeostasis in the majority of cases, and at least five cases had evidence of disrupted lung growth. CONCLUSIONS Patients with mutations in NKX2-1 may present with pulmonary manifestations in the newborn period or during childhood when thyroid or neurologic abnormalities are not apparent. Surfactant dysfunction and, in more severe cases, disrupted lung development are likely mechanisms for the respiratory disease.

Measuring Critical Thinking in Problem-Based Learning Discourse

Background: Critical thinking (CT) is a composite of skills linked to problem-based learning (PBL). Purposes: This study has 3 purposes: (a) to determine if PBL discourse could be coded for CT, (b) to demonstrate reliable coding, and (c) to determine whether a CT ratio would provide a valid measure to compare 2 PBL groups. Methods: Using prior research, we refined the code for a content analysis of PBL transcripts. Raters coded 6 hr of transcripts and computed CT ratios for each of the 5 CT stages. Average interrater agreement was 85.5%. CT ratios appeared to differ between 2 PBL groups delivered in 2 modalities. Results: PBL discourse could be coded following a CT framework. Independent raters reliably applied the code, and the resulting CT ratios detected tenable differences. Conclusions: This approach could provide useful information about the effect of case modality.

Familial neuroendocrine cell hyperplasia of infancy.

Neuroendocrine cell hyperplasia of infancy (NEHI) is a recently described childrens interstitial lung disease (chILD) disorder of unknown etiology. It manifests clinically with tachypnea, retractions, hypoxemia, and crackles. The characteristic radiographic appearance consists of pulmonary hyperexpansion and ground‐glass densities on high‐resolution computed tomography (HRCT). Lung histology shows hyperplasia of bombesin‐immunopositive neuroendocrine cells within distal bronchioles and alveolar ducts without other identifiable lung pathology or developmental anomaly.

Pulmonary veno-occlusive disease after autologous bone marrow transplant in a child with stage IV neuroblastoma: case report and literature review.

Pulmonary veno-occlusive disease (PVOD) is a rare, almost universally fatal complication of chemotherapy and bone marrow transplantation with few treatment options. A 19-month-old boy with stage 4 neuroblastoma with fatal PVOD following high-dose chemotherapy with autologous peripheral blood stem cell rescue is described here. A comprehensive literature review revealed 40 case reports of PVOD in oncology patients. Various therapeutic modalities were attempted, with four survivors. PVOD should be considered in patients with dyspnea and cardiomegaly. Less invasive diagnostic methods and more effective therapies are needed.

Regeneration of Thyroid Function by Transplantation of Differentiated Pluripotent Stem Cells

Differentiation of functional thyroid epithelia from pluripotent stem cells (PSCs) holds the potential for application in regenerative medicine. However, progress toward this goal is hampered by incomplete understanding of the signaling pathways needed for directed differentiation without forced overexpression of exogenous transgenes. Here we use mouse PSCs to identify key conserved roles for BMP and FGF signaling in regulating thyroid lineage specification from foregut endoderm in mouse and Xenopus. Thyroid progenitors derived from mouse PSCs can be matured into thyroid follicular organoids that provide functional secretion of thyroid hormones in vivo and rescue hypothyroid mice after transplantation. Moreover, by stimulating the same pathways, we were also able to derive human thyroid progenitors from normal and disease-specific iPSCs generated from patients with hypothyroidism resulting from NKX2-1 haploinsufficiency. Our studies have therefore uncovered the regulatory mechanisms that underlie early thyroid organogenesis and provide a significant step toward cell-based regenerative therapy for hypothyroidism.