Cryoextraction via flexible bronchoscopy in children with tracheobronchial obstruction

BACKGROUND

Cryoextraction via flexible bronchoscopy (FB) can be used to alleviate airway obstruction due to blood clots, casts, mucus, and foreign bodies. There is limited literature regarding the utility of cryoextraction to restore airway patency in critically ill children, especially on extracorporeal membrane oxygenation (ECMO). The aims of this study were to describe the clinical course and outcomes of children who underwent cryoextraction via FB.

METHODS

A singlecenter retrospective review of children who underwent cryoextraction via FB between 2017 and 2021 was conducted. The analyzed data included diagnoses, indications for cryoextraction, respiratory support modalities, FB and chest imaging results, and outcomes.

RESULTS

Eleven patients aged 3-17 years underwent a total of 33 cryoextraction sessions via FB. Patients required ECMO (n = 9) or conventional mechanical ventilation (CMV) for pneumonia, pulmonary hemorrhage, pulmonary embolism, asthma exacerbation, and cardiorespiratory failure following cardiac surgery. One patient underwent elective FB and cryoextraction for plastic bronchitis. Indications for cryoextraction included airway obstruction due to tracheobronchial thrombi (n = 8), mucus plugs (n = 1), or plastic bronchitis (n = 2). Cryoextraction via FB was performed on patients on ECMO (n = 9) and CMV (n = 2) with 6 patients requiring ≥3 cryoextraction sessions for airway obstruction. There were no complications related to cryoextraction. Patient outcomes included partial (n = 5) or complete (n = 6) restoration of airway patency with ECMO decannulation (n = 5) and death (n = 4) due to critical illness.

CONCLUSIONS

Cryoextraction via FB is an effective intervention that can be utilized in critically ill children with refractory tracheobronchial obstruction to restore airway patency and to facilitate liberation from ECMO.

Outpatient Utilization of the RAM Cannula for Nasal Noninvasive Ventilation in Children

Background

The RAM cannula® consists of nasal prongs that can be used to administer oxygen, continuous, and bilevel positive airway pressure therapies. Studies have reported the efficacy and utility of the RAM cannula in inpatients requiring noninvasive ventilation (NIV); however, there is limited literature on the use of the RAM cannula to provide NIV in the outpatient setting.

Objectives

This study aimed to describe the clinical features and outcomes of children who used NIV via RAM cannula in the outpatient setting.

Design

Retrospective review.

Methods

We conducted a retrospective review of children treated with outpatient NIV via RAM cannula at our institution between January 2010 and March 2023. The analyzed data included age, diagnoses, indications for NIV, duration of RAM cannula use, complications, and outcomes at 6 months.

Results

We identified 20 patients who used outpatient NIV via RAM cannula during the study period. The median age at initiation of NIV via RAM cannula was 5.8 months (IQR 2.4-9.9 months). Indications for NIV included sleep-related hypoventilation (15%), restrictive lung disease (25%), obstructive sleep apnea (45%), and chronic respiratory failure (50%), with 6 patients having ⩾2 indications for NIV. RAM cannula was utilized for inability to tolerate conventional NIV interfaces (80%), to alleviate dyspnea (60%), and to avoid tracheostomy (55%). Patients used NIV via RAM cannula for a median duration of 7.7 months (IQR 3.7-20.6 months). Patient outcomes included ongoing usage of RAM cannula (55%), changing to conventional NIV interfaces (15%) or oxygen (10%), weaning off respiratory support (5%), and death (15%). There were no complications related to using the RAM cannula.

Conclusion

Our study demonstrates the utility of outpatient NIV via RAM cannula in children with a variety of diagnoses until clinical improvement or tolerance of conventional interfaces, and for avoidance of tracheostomy.

External airway splint placement for severe pediatric tracheobronchomalacia

OBJECTIVE

To present external airway splinting with bioabsorbable airway supportive devices (ASD) for severe, life-threatening cases of pediatric tracheomalacia (TM) or tracheobronchomalacia (TBM).

METHODS

A retrospective cohort was performed for 5 pediatric patients with severe TM or TBM who underwent ASD placement. Devices were designed and 3D-printed from a bioabsorbable material, polycaprolactone (PCL). Pre-operative planning included 3-dimensional airway modeling of tracheal collapse and tracheal suture placement using nonlinear finite element (FE) methods. Pre-operative modeling revealed that triads along the ASD open edges and center were the most effective suture locations for optimizing airway patency. Pediatric cardiothoracic surgery and otolaryngology applied the ASDs by suspending the trachea to the ASD with synchronous bronchoscopy. Respiratory needs were trended for all cases. Data from pediatric patients with tracheostomy and diagnosis of TM or TBM, but without ASD, were included for discussion.

RESULTS

Five patients (2 Females, 3 Males, ages 2-9 months at time of ASD) were included. Three patients were unable to wean from respiratory support after vascular ring division; all three weaned to room air post-ASD. Two patients received tracheostomies prior to ASD placement, but continued to experience apparent life-threatening events (ALTE) and required ventilation with supraphysiologic ventilator settings. One patient weaned respiratory support successfully after ASD placement. The last patient died post-ASD due to significant respiratory co-morbidity.

CONCLUSION

ASD can significantly benefit patients with severe, unrelenting tracheomalacia or tracheobronchomalacia. Proper multidisciplinary case deliberation and selection are key to success with ASD. Pre-operative airway modeling allows proper suture placement to optimally address the underlying airway collapse.

Ventilator change in children on home mechanical ventilation affected by the Philips respironics trilogy ventilator recall

The Philips Respironics recall notification issued in June 2021 affected many of their positive airway pressure devices and mechanical ventilators including the Trilogy 100 and 200 ventilators that are often utilized in children using home positive pressure ventilation via tracheostomy (PPV-T). Optimal strategies to replace ventilators in children using home PPV-T affected by the Philips recall are unknown. We conducted a retrospective study of children using home PPV-T with recalled Trilogy ventilators who underwent inpatient ventilator change to non-recalled portable home ventilators (PHV) using our collaborative institutional protocol. During the study period, there were 40 children using PPV-T with recalled Trilogy ventilators and 19 patients underwent inpatient ventilator change either during an elective hospitalization (n = 8) or during an unscheduled or postoperative hospitalization (n = 11). The median duration of hospitalization for ventilator change was 2 days (interquartile range: 6 days) and generally 1 day for patients admitted solely for ventilator change. In children using PPV-T with recalled Trilogy ventilators, a systematic protocol collaborating with the patients, physicians, and durable medical equipment companies may optimize transition to nonrecalled PHVs.

Bronchoscopic interventions for plastic bronchitis in children without structural heart disease

Plastic bronchitis (PB) is a rare and life-threatening complication encountered in several disease states that leads to airway obstruction by branching casts. PB is most often reported in children with cyanotic congenital heart disease where recurrence is common, and mortality is high. There is limited data on optimal management strategies or recurrence of non-structural heart disease-related PB in children. We describe the clinical features, management, and outcomes in our cohort of children with non-structural heart disease-related PB. Among the 12 identified patients, asthma was the most common (67%) diagnosis. Ventilatory requirements ranged from room air to one patient who required extracorporeal membrane oxygenation (ECMO). Most patients (92%) required bronchoscopy, and cryotherapy was successfully utilized in two patients to relieve refractory obstructive airway casts. All patients received chest physiotherapy, and 11 patients were treated with two or more medications. There was one mortality despite ECMO, and one-third had recurrent PB, all of whom had asthma.Conclusion: Asthma is a risk factor for recurrent PB. Bronchoscopic interventions including cryotherapy are safe and effective treatment options in patients with refractory PB. What is Known: • Plastic bronchitis is a rare but life-threatening cause of airway obstruction caused by branching casts that are generally reported in patients with congenital heart disease. What is New: • In children without structural heart disease, asthma is a risk factor for recurrent plastic bronchitis. Cryotherapy via bronchoscopy is a safe and effective intervention in patients with refractory plastic bronchitis.

Heterogeneous Pulmonary Phenotypes in Filamin A Mutation-Related Lung Disease

Background: Interstitial lung disease (ILD) has been recently reported in a few patients with pathogenic variants in the Filamin A (FLNA) gene with variable presentation and prognosis. This study evaluated the respiratory manifestations and clinical features in children with FLNA disease. Methods: We conducted a retrospective review of pediatric patients with variants in FLNA in a tertiary children's hospital. The clinical features, genotype, management, and outcomes were analyzed. Results: We identified 9 patients with variants in FLNA aged 15 months to 24 years, 4 females and 5 males. Six patients had abnormal chest imaging ranging from mild interstitial prominence to atelectasis, interstitial densities, and hyperinflation. Three patients with ILD presented during the neonatal period or early infancy with respiratory distress or respiratory failure requiring supplemental oxygen or assisted ventilation via tracheostomy. We report male twins with the same FLNA variant and lung disease, but different ages and clinical features at presentation eventually culminating in respiratory failure requiring assisted ventilation. All patients had FLNA variants identified by FLNA sequencing, had abnormal echocardiograms, and none of the patients underwent lung biopsy or lung transplantation. The outcomes were variable and could be as severe as chronic respiratory failure. Conclusion: The wide spectrum of respiratory manifestations and abnormal chest imaging in our study highlights the importance of evaluation for lung disease in patients with variants in FLNA. FLNA sequencing in suspected cases with ILD may obviate the need for a lung biopsy, prompt surveillance for progressive lung disease, and evaluation for associated clinical features.

An instructional definition and assessment rubric for bioinformatics instruction

The lack of an instructional definition of bioinformatics delays its effective integration into biology coursework. Using an iterative process, our team of biologists, a mathematician/computer scientist, and a bioinformatician together with an educational evaluation and assessment specialist, developed an instructional definition of the discipline: Bioinformatics is "an interdisciplinary field that is concerned with the development and application of algorithms that analyze biological data to investigate the structure and function of biological polymers and their relationships to living systems." The field is defined in terms of its two primary foundational disciplines, biology and computer science, and its interdisciplinary nature. At the same time, we also created a rubric for assessing open-ended responses to a prompt about what bioinformatics is and how it is used. The rubric has been shown to be reliable in successive rounds of testing using both common percent agreement (89.7%) and intraclass correlation coefficient (0.620) calculations. We offer the definition and rubric to life sciences instructors to help further integrate bioinformatics into biology instruction, as well as for fostering further educational research projects.

Mortality and Outcomes of Pediatric Tracheostomy Dependent Patients

Objective: To describe clinical factors associated with mortality and causes of death in tracheostomy-dependent (TD) children. Methods: A retrospective study of patients with a new or established tracheostomy requiring hospitalization at a large tertiary children's hospital between 2009 and 2015 was conducted. Patient groups were developed based on indication for tracheostomy: pulmonary, anatomic/airway obstruction, and neurologic causes. The outcome measures were overall mortality rate, mortality risk factors, and causes of death. Results: A total of 187 patients were identified as TD with complete data available for 164 patients. Primary indications for tracheostomy included pulmonary (40%), anatomic/airway obstruction (36%), and neurologic (24%). The median age at tracheostomy and duration of follow up were 6.6 months (IQR 3.5-19.5 months) and 23.8 months (IQR 9.9-46.7 months), respectively. Overall, 45 (27%) patients died during the study period and the median time to death following tracheostomy was 9.8 months (IQR 6.1-29.7 months). Overall survival at 1- and 5-years following tracheostomy was 83% (95% CI: 76-88%) and 68% (95% CI: 57-76%), respectively. There was no significant difference in mortality based on indication for tracheostomy (p = 0.35), however pulmonary indication for tracheostomy was associated with a shorter time to death (HR: 1.9; 95% CI: 1.04-3.4; p = 0.04). Among the co-morbid medical conditions, children with seizure disorder had higher mortality (p = 0.04). Conclusion: In this study, TD children had a high mortality rate with no significant difference in mortality based on indication for tracheostomy. Pulmonary indication for tracheostomy was associated with a shorter time to death and neurologic indication was associated with lower decannulation rates.

Patterns of Bird-Bacteria Associations

Birds, with their broad geographic ranges and close association with humans, have historically played an important role as carriers of human disease and as reservoirs for drug-resistant bacteria. Here, we examine scientific literature over a 15-year timespan to identify reported avian-bacterial associations and factors that may impact zoonotic disease emergence by classifying traits of bird species and their bacteria. We find that the majority of wild birds studied were migratory, in temperate habitats, and in the order Passeriformes. The highest diversity of bacteria was found on birds in natural habitats. The most frequently reported bacteria were Escherichia coli, Salmonella enterica, and Campylobacter jejuni. Of the bacteria species reported, 54% have shown pathogenicity toward humans. Percentage-wise, more pathogens were found in tropical (vs. temperate) habitats and natural (vs. suburban, urban, or agricultural) habitats. Yet, only 22% were tested for antibiotic resistance, and of those tested, 75% of bacteria species were resistant to at least one antibiotic. There were no significant patterns of antibiotic resistance in migratory versus non-migratory birds, temperate versus tropical areas, or different habitats. We discuss biases in detection and representation, and suggest a need for increased sampling in non-temperate zones and in a wider range of avian species.

Airway epithelial cell PPARγ modulates cigarette smoke-induced chemokine expression and emphysema susceptibility in mice

Chronic obstructive pulmonary disease (COPD) is a highly prevalent, chronic inflammatory lung disease with limited existing therapeutic options. While modulation of peroxisome proliferator-activating receptor (PPAR)-γ activity can modify inflammatory responses in several models of lung injury, the relevance of the PPARG pathway in COPD pathogenesis has not been previously explored. Mice lacking Pparg specifically in airway epithelial cells displayed increased susceptibility to chronic cigarette smoke (CS)-induced emphysema, with excessive macrophage accumulation associated with increased expression of chemokines, Ccl5, Cxcl10, and Cxcl15. Conversely, treatment of mice with a pharmacological PPARγ activator attenuated Cxcl10 and Cxcl15 expression and macrophage accumulation in response to CS. In vitro, CS increased lung epithelial cell chemokine expression in a PPARγ activation-dependent fashion. The ability of PPARγ to regulate CS-induced chemokine expression in vitro was not specifically associated with peroxisome proliferator response element (PPRE)-mediated transactivation activity but was correlated with PPARγ-mediated transrepression of NF-κB activity. Pharmacological or genetic activation of PPARγ activity abrogated CS-dependent induction of NF-κB activity. Regulation of NF-κB activity involved direct PPARγ-NF-κB interaction and PPARγ-mediated effects on IKK activation, IκBα degradation, and nuclear translocation of p65. Our data indicate that PPARG represents a disease-relevant pathophysiological and pharmacological target in COPD. Its activation state likely contributes to NF-κB-dependent, CS-induced chemokine-mediated regulation of inflammatory cell accumulation.

Alternative splicing of a group II intron in a surface layer protein gene in Clostridium tetani

Group II introns are ribozymes and retroelements found in bacteria, and are thought to have been the ancestors of nuclear pre-mRNA introns. Whereas nuclear introns undergo prolific alternative splicing in some species, group II introns are not known to carry out equivalent reactions. Here we report a group II intron in the human pathogen Clostridium tetani, which undergoes four alternative splicing reactions in vivo. Together with unspliced transcript, five mRNAs are produced, each encoding a distinct surface layer protein isoform. Correct fusion of exon reading frames requires a shifted 5′ splice site located 8 nt upstream of the canonical boundary motif. The shifted junction is accomplished by an altered IBS1-EBS1 pairing between the intron and 5′ exon. Growth of C. tetani under a variety of conditions did not result in large changes in alternative splicing levels, raising the possibility that alternative splicing is constitutive. This work demonstrates a novel type of gene organization and regulation in bacteria, and provides an additional parallel between group II and nuclear pre-mRNA introns.

A diversity of Antibiotic-resistant Staphylococcus spp. in a Public Transportation System

OBJECTIVES

Our goal was to determine the diversity and abundance of Staphylococcus bacteria on different components of a public transportation system in a mid-sized US city (Portland, Oregon) and to examine the level of drug resistance in these bacteria.

METHODS

We collected 70 samples from 2 cm × 4 cm sections from seven different areas on buses and trains in Portland, USA, taking 10 samples from each area. We isolated a subset of 14 suspected Staphylococcus spp. colonies based on phenotype, and constructed a phylogeny from16S rRNA sequences to assist in identification. We used the Kirbye-Bauer disk diffusion method to determine resistance levels to six common antibiotics.

RESULTS

We found a range of pathogenic Staphylococcus species. The mean bacterial colony counts were 97.1 on bus and train floors, 80.1 in cloth seats, 9.5 on handrails, 8.6 on seats and armrests at bus stops, 3.8 on the underside of seats, 2.2 on windows, and 1.8 on vinyl seats per 8 cm(2) sample area. These differences were significant (p < 0.001). Of the 14 isolates sequenced, 11 were staphylococci, and of these, five were resistant to penicillin and ampicillin, while only two displayed intermediate resistance to bacitracin. All 11 isolates were sensitive to trimethoprim-sulfamethoxazole, vancomycin, and tetracycline.

CONCLUSIONS

We found six different strains of Staphylococcus, and while there were varying levels of drug resistance, we did not find extensive levels of multidrug-resistant bacteria, and no S. aureus was found. We found floors and cloth seats to be areas on buses and trains that showed particularly high levels of bacteria.

Role of PPARs and Retinoid X Receptors in the Regulation of Lung Maturation and Development

Understanding lung development has significant importance to public health because of the fact that interruptions in the normal developmental processes can have prominent effects on childhood and adult lung health. It is widely appreciated that the retinoic acid (RA) pathway plays an important role in lung development. Additionally, PPARs are believed to partner with receptors of this pathway and therefore could be considered extensions of retinoic acid function, including during lung development. This review will begin by introducing the relationship between the retinoic acid pathway and PPARs followed by an overview of lung development stages and regulation to conclude with details on PPARs and the retinoic acid pathway as they may relate to lung development.

Transmission of human immunodeficiency virus and hepatitis C virus from an organ donor to four transplant recipients

In 2007, a previously uninfected kidney transplant recipient tested positive for human immunodeficiency virus type 1 (HIV) and hepatitis C virus (HCV) infection. Clinical information of the organ donor and the recipients was collected by medical record review. Sera from recipients and donor were tested for serologic and nucleic acid-based markers of HIV and HCV infection, and isolates were compared for genetic relatedness. Routine donor serologic screening for HIV and HCV infection was negative; the donor's only known risk factor for HIV was having sex with another man. Four organs (two kidneys, liver and heart) were transplanted to four recipients. Nucleic acid testing (NAT) of donor sera and posttransplant sera from all recipients were positive for HIV and HCV. HIV nucleotide sequences were indistinguishable between the donor and four recipients, and HCV subgenomic sequences clustered closely together. Two patients subsequently died and the transplanted organs failed in the other two patients. This is the first recognized cotransmission of HIV and HCV from an organ donor to transplant recipients. Routine posttransplant HIV and HCV serological testing and NAT of recipients of organs from donors with suspected risk factors should be considered as routine practice.

Thiol redox disturbances in children with severe asthma are associated with posttranslational modification of the transcription factor nuclear factor (erythroid-derived 2)-like 2

BACKGROUND

Airway thiol redox disturbances, including depletion of the antioxidant, glutathione, are differentiating features of severe asthma in children.

OBJECTIVES

Given the role of the transcription factor nuclear factor (erythroid-derived 2)-like 2 (Nrf2) in maintaining glutathione homeostasis and antioxidant defense, we quantified expression and activity of Nrf2 and its downstream targets in the airways and systemic circulation of children with asthma. We hypothesized that Nrf2 activation and function would be impaired in severe asthma, resulting in depletion of thiol pools and insufficient glutathione synthesis and conjugation.

METHODS

PBMCs and airway lavage cells were collected from children 6 to 17 years with severe (n = 51) and mild-to-moderate asthma (n = 38). The thiols glutathione and cysteine were quantified, and expression and activity of Nrf2 and its downstream targets were assessed.

RESULTS

Children with severe asthma had greater oxidation and lower concentrations of glutathione and cysteine in the plasma and airway lavage. Although Nrf2 mRNA and protein increased in severe asthma as a function of increased thiol oxidation, the Nrf2 expressed was highly dysfunctional. Nrf2 activation and downstream targets of Nrf2 binding, including glutathione-dependent enzymes, were not different between groups. The duration of asthma was a key factor associated with Nrf2 dysfunction in severe asthma.

CONCLUSION

Children with severe asthma have a global disruption of thiol redox signaling and control in both the airways and systemic circulation that is associated with posttranslational modification of Nrf2. We conclude that the Nrf2 pathway is disrupted in severe asthma as a function of chronic oxidative stress, which ultimately inhibits glutathione synthesis and antioxidant defense.

PPARgamma deficiency results in reduced lung elastic recoil and abnormalities in airspace distribution

Background

Peroxisome proliferator-activated receptor (PPAR)-γ is a nuclear hormone receptor that regulates gene expression, cell proliferation and differentiation. We previously described airway epithelial cell PPARγ deficient mice that develop airspace enlargement with decreased tissue resistance and increased lung volumes. We sought to understand the impact of airspace enlargement in conditionally targeted mice upon the physio-mechanical properties of the lung.

Methods

We measured elastic recoil and its determinants, including tissue structure and surface forces. We measured alveolar number using radial alveolar counts, and airspace sizes and their distribution using computer-assisted morphometry.

Results

Air vs. saline-filled pressure volume profiles demonstrated loss of lung elastic recoil in targeted mice that was contributed by both tissue components and surface tension, but was proportional to lung volume. There were no significant differences in surfactant quantity/function nor in elastin and collagen content between targeted animals and littermate controls. Importantly, radial alveolar counts were significantly reduced in the targeted animals and at 8 weeks of age there were 18% fewer alveoli with 32% more alveolar ducts. Additionally, the alveolar ducts were 19% larger in the targeted animals.

Conclusions

Our data suggest that the functional abnormalities, including loss of recoil are secondary to altered force transmission due to differences in the structure of alveolar ducts, rather than changes in surfactant function or elastin or collagen content. These data further define the nature of abnormal lung maturation in the absence of airway epithelial cell PPARγ and identify a putative genetic determinant of dysanapsis, which may serve as a precursor to chronic lung disease.

The Puf family of RNA-binding proteins in plants: phylogeny, structural modeling, activity and subcellular localization

BACKGROUND

Puf proteins have important roles in controlling gene expression at the post-transcriptional level by promoting RNA decay and repressing translation. The Pumilio homology domain (PUM-HD) is a conserved region within Puf proteins that binds to RNA with sequence specificity. Although Puf proteins have been well characterized in animal and fungal systems, little is known about the structural and functional characteristics of Puf-like proteins in plants.

RESULTS

The Arabidopsis and rice genomes code for 26 and 19 Puf-like proteins, respectively, each possessing eight or fewer Puf repeats in their PUM-HD. Key amino acids in the PUM-HD of several of these proteins are conserved with those of animal and fungal homologs, whereas other plant Puf proteins demonstrate extensive variability in these amino acids. Three-dimensional modeling revealed that the predicted structure of this domain in plant Puf proteins provides a suitable surface for binding RNA. Electrophoretic gel mobility shift experiments showed that the Arabidopsis AtPum2 PUM-HD binds with high affinity to BoxB of the Drosophila Nanos Response Element I (NRE1) RNA, whereas a point mutation in the core of the NRE1 resulted in a significant reduction in binding affinity. Transient expression of several of the Arabidopsis Puf proteins as fluorescent protein fusions revealed a dynamic, punctate cytoplasmic pattern of localization for most of these proteins. The presence of predicted nuclear export signals and accumulation of AtPuf proteins in the nucleus after treatment of cells with leptomycin B demonstrated that shuttling of these proteins between the cytosol and nucleus is common among these proteins. In addition to the cytoplasmically enriched AtPum proteins, two AtPum proteins showed nuclear targeting with enrichment in the nucleolus.

CONCLUSIONS

The Puf family of RNA-binding proteins in plants consists of a greater number of members than any other model species studied to date. This, along with the amino acid variability observed within their PUM-HDs, suggests that these proteins may be involved in a wide range of post-transcriptional regulatory events that are important in providing plants with the ability to respond rapidly to changes in environmental conditions and throughout development.

Endoscopic repair of laryngeal cleft type I and type II: when and why?

OBJECTIVES/HYPOTHESIS

To evaluate the clinical features of children with type I and type II laryngeal cleft and the role of conservative monitoring versus endoscopic repair in their management.

METHODS

Clinical presentation and evaluation; findings at the time of laryngoscopy, bronchoscopy, and esophagoscopy; and efficacy and outcome of conservative monitoring and endoscopic CO(2) laser repair.

RESULTS

Eighty-one patients were evaluated for aspiration. Seventy-four patients were diagnosed as having a clinically significant laryngeal cleft. Thirty-two patients (14 males, 18 females) were monitored conservatively. Forty-nine patients (26 males, 23 females) required surgical intervention due to failed medical and feeding therapy of aspiration related to their laryngeal clefts (28 type I, 21 type II). Endoscopic CO(2) laser repair was used in all these patients.

CONCLUSIONS

Medical and feeding therapy should be the first modality of treatment in patients with laryngeal cleft type I and type II. Factors supporting surgical repair include: 1) clinically apparent aspiration with feeding, 2) severity of pulmonary status, 3) findings on modified barium swallow and chest x-ray, 4) absence of significant comorbid conditions predisposing to aspiration, 5) findings on upper aerodigestive endoscopy, and 6) poor response to medical management and feeding therapy.

Fibroblast growth factor receptors control epithelial-mesenchymal interactions necessary for alveolar elastogenesis

RATIONALE

The mechanisms contributing to alveolar formation are poorly understood. A better understanding of these processes will improve efforts to ameliorate lung disease of the newborn and promote alveolar repair in the adult. Previous studies have identified impaired alveogenesis in mice bearing compound mutations of fibroblast growth factor (FGF) receptors (FGFRs) 3 and 4, indicating that these receptors cooperatively promote postnatal alveolar formation.

OBJECTIVES

To determine the molecular and cellular mechanisms of FGF-mediated alveolar formation.

METHODS

Compound FGFR3/FGFR4-deficient mice were assessed for temporal changes in lung growth, airspace morphometry, and genome-wide expression. Observed gene expression changes were validated using quantitative real-time RT-PCR, tissue biochemistry, histochemistry, and ELISA. Autocrine and paracrine regulatory mechanisms were investigated using isolated lung mesenchymal cells and type II pneumocytes.

MEASUREMENTS AND MAIN RESULTS

Quantitative analysis of airspace ontogeny confirmed a failure of secondary crest elongation in compound mutant mice. Genome-wide expression profiling identified molecular alterations in these mice involving aberrant expression of numerous extracellular matrix molecules. Biochemical and histochemical analysis confirmed changes in elastic fiber gene expression resulted in temporal increases in elastin deposition with the loss of typical spatial restriction. No abnormalities in elastic fiber gene expression were observed in isolated mesenchymal cells, indicating that abnormal elastogenesis in compound mutant mice is not cell autonomous. Increased expression of paracrine factors, including insulin-like growth factor-1, in freshly-isolated type II pneumocytes indicated that these cells contribute to the observed pathology.

CONCLUSIONS

Epithelial/mesenchymal signaling mechanisms appear to contribute to FGFR-dependent alveolar elastogenesis and proper airspace formation.

A broadscale phylogenetic analysis of group II intron RNAs and intron-encoded reverse transcriptases

Group II introns are self-splicing RNAs that are frequently assumed to be the ancestors of spliceosomal introns. They are widely distributed in bacteria and are also found in organelles of plants, fungi, and protists. In this study, we present a broadscale phylogenetic analysis of group II introns using sequence data from both the conserved RNA structure and the intron-encoded reverse transcriptase (RT). Two similar phylogenies are estimated for the RT open reading frame (ORF), based on either amino acid or nucleotide sequence, whereas one phylogeny is produced for the RNA. In making these estimates, we confronted nearly all the classic challenges to phylogenetic inference, including positional saturation, base composition heterogeneity, short internodes with low support, and sensitivity to taxon sampling. Although the major lineages are well-defined, robust resolution of topology is not possible between these lineages. The approximately unbiased (AU) and Shimodaira-Hasegawa topology tests indicated that the RT ORF and RNA ribozyme data sets are in significant conflict under a variety of models, revealing the possibility of imperfect coevolution between group II introns and their intron-encoded ORFs. The high level of sequence divergence, large timescale, and limited number of alignable characters in our study are representative of many RTs and group I introns, and our results suggest that phylogenetic analyses of any of these sequences could suffer from the same sources of error and instability identified in this study.

A diversity of uncharacterized reverse transcriptases in bacteria

Retroelements are usually considered to be eukaryotic elements because of the large number and variety in eukaryotic genomes. By comparison, reverse transcriptases (RTs) are rare in bacteria, with only three characterized classes: retrons, group II introns and diversity-generating retroelements (DGRs). Here, we present the results of a bioinformatic survey that aims to define the landscape of RTs across eubacterial, archaeal and phage genomes. We identify and categorize 1021 RTs, of which the majority are group II introns (73%). Surprisingly, a plethora of novel RTs are found that do not belong to characterized classes. The RTs have 11 domain architectures and are classified into 20 groupings based on sequence similarity, phylogenetic analyses and open reading frame domain structures. Interestingly, group II introns are the only bacterial RTs to exhibit clear evidence for independent mobility, while five other groups have putative functions in defense against phage infection or promotion of phage infection. These examples suggest that additional beneficial functions will be discovered among uncharacterized RTs. The study lays the groundwork for experimental characterization of these highly diverse sequences and has implications for the evolution of retroelements.

Group II introns in eubacteria and archaea: ORF-less introns and new varieties

Group II introns are a major class of ribozymes found in bacteria, mitochondria, and plastids. Many introns contain reverse transcriptase open reading frames (ORFs) that confer mobility to the introns and allow them to persist as selfish DNAs. Here, we report an updated compilation of group II introns in Eubacteria and Archaea comprising 234 introns. One new phylogenetic class is identified, as well as several specialized lineages. In addition, we undertake a detailed search for ORF-less group II introns in bacterial genomes in order to find undiscovered introns that either entirely lack an ORF or encode a novel ORF. Unlike organellar group II introns, we find only a handful of ORF-less introns in bacteria, suggesting that if a substantial number exist, they must be divergent from known introns. Together, these results highlight the retroelement character of bacterial group II introns, and suggest that their long-term survival is dependent upon retromobility.

Herpes simplex virus hepatitis: expanding the spectrum of disease

We describe 2 transplant patients with herpes simplex virus (HSV) hepatitis who were minimally symptomatic throughout their illness. The spectrum of disease caused by HSV hepatitis is more variable than previously reported in this population. HSV hepatitis should be considered in immunocompromised hosts with elevated transaminases without evidence of fulminant hepatic necrosis.

Epithelial cell PPAR[gamma] contributes to normal lung maturation

Peroxisome proliferator-activated receptor (PPAR)-gamma is a member of the nuclear hormone receptor superfamily that can promote cellular differentiation and organ development. PPARgamma expression has been reported in a number of pulmonary cell types, including inflammatory, mesenchymal, and epithelial cells. We find that PPARgamma is prominently expressed in the airway epithelium in the mouse lung. In an effort to define the physiological role of PPARgamma within the lung, we have ablated PPARgamma using a novel line of mice capable of specifically targeting the airway epithelium. Airway epithelial cell PPARgamma-targeted mice display enlarged airspaces resulting from insufficient postnatal lung maturation. The increase in airspace size is accompanied by alterations in lung physiology, including increased lung volumes and decreased tissue resistance. Genome-wide expression profiling reveals a reduction in structural extracellular matrix (ECM) gene expression in conditionally targeted mice, suggesting a disruption in epithelial-mesenchymal interactions necessary for the establishment of normal lung structure. Expression profiling of airway epithelial cells isolated from conditionally targeted mice indicates PPARgamma regulates genes encoding known PPARgamma targets, additional lipid metabolism enzymes, and markers of cellular differentiation. These data reveal airway epithelial cell PPARgamma is necessary for normal lung structure and function.

Phylogenetic analyses suggest reverse splicing spread of group I introns in fungal ribosomal DNA

BACKGROUND

Group I introns have spread into over 90 different sites in nuclear ribosomal DNA (rDNA) with greater than 1700 introns reported in these genes. These ribozymes generally spread through endonuclease-mediated intron homing. Another putative pathway is reverse splicing whereby a free group I intron inserts into a homologous or heterologous RNA through complementary base-pairing between the intron and exon RNA. Reverse-transcription of the RNA followed by general recombination results in intron spread. Here we used phylogenetics to test for reverse splicing spread in a taxonomically broadly sampled data set of fungal group I introns including 9 putatively ancient group I introns in the rDNA of the yeast-like symbiont Symbiotaphrina buchneri.

RESULTS

Our analyses reveal a complex evolutionary history of the fungal introns with many cases of vertical inheritance (putatively for the 9 introns in S. buchneri) and intron lateral transfer. There are several examples in which introns, many of which are still present in S. buchneri, may have spread through reverse splicing into heterologous rDNA sites. If the S. buchneri introns are ancient as we postulate, then group I intron loss was widespread in fungal rDNA evolution.

CONCLUSION

On the basis of these results, we suggest that the extensive distribution of fungal group I introns is at least partially explained by the reverse splicing movement of existing introns into ectopic rDNA sites.

Heterogeneity of intron presence or absence in rDNA genes of the lichen species Physcia aipolia and P. stellaris

Intron origin and evolution are of high interest, yet the rates of insertion and loss are unclear. To investigate their spread, we studied ribosomal (r)DNA introns from the closely related lichens Physcia aipolia and P. stellaris. Both taxa are replete with rDNA spliceosomal introns and autocatalytic group I introns, many of which show presence/absence polymorphism when screened with the PCR approach. This initially suggested that Physcia could be a model for studying intron retention and loss. However, during the course of a population-level analysis, we discovered widespread intron presence/absence heterogeneity within lichen thalli. To address this result, we sequenced multiple clones encoding nuclear rDNA and the single-copy elongation factor-1alpha (EF-1alpha) from individual thalli. These data showed extensive rDNA heterogeneity within individuals, rather than the presence of multiple fungi within a thallus. Our results suggest that considerable care must be taken when interpreting intron presence/absence in lichen rDNA, an observation that has general implications for the study of rDNA intron evolution.

The natural history of group I introns

There are four major classes of introns: self-splicing group I and group II introns, tRNA and/or archaeal introns and spliceosomal introns in nuclear pre-mRNA. Group I introns are widely distributed in protists, bacteria and bacteriophages. Group II introns are found in fungal and land plant mitochondria, algal plastids, bacteria and Archaea. Group II and spliceosomal introns share a common splicing pathway and might be related to each other. The tRNA and/or archaeal introns are found in the nuclear tRNA of eukaryotes and in archaeal tRNA, rRNA and mRNA. The mechanisms underlying the self-splicing and mobility of a few model group I introns are well understood. By contrast, the role of these highly distinct processes in the evolution of the 1500 group I introns found thus far in nature (e.g. in algae and fungi) has only recently been clarified. The explosion of new sequence data has facilitated the use of comparative methods to understand group I intron evolution in a broader context and to generate hypotheses about intron insertion, splicing and spread that can be tested experimentally.

Repair of aneurysmal aortic coarctation in an octogenarian

An 80-year-old man presented with a descending thoracic aortic aneurysm. Computed tomography and aortography revealed a large aneurysm and tight aortic coarctation. This was successfully repaired with an interposition prosthesis.

Infectious complications of solid organ transplantations

The rate of infectious complications in SOT recipients has declined dramatically. As improvements in immunosuppressive therapy, surgical techniques, and diagnostics and antimicrobial treatment continue, further declines in infectious complications are expected. Refinements to preemptive therapy for high-risk patients are likely to contribute further to this decrease. Further investigation is required to define what role various infectious agents play in chronic allograft injury and rejection.

Acquired neurologic deficits in young children: a diagnostic journey with Dora

Young children with limited communication abilities are often difficult to diagnose. When a neurologic insult occurs prior to language development, the communication effects tend to be less predictable than when the same event occurs in an older child or in an adult with a history of "normal" language use. Information in the medical chart regarding status during prelinguistic periods for cognition, motor, and verbal function should be helpful in predicting outcomes in some instances, but a series of decisions, over time, are likely to be necessary to reach a definitive communication diagnosis. As children become more verbal, the characteristics of the motor speech system can lead to new or changing diagnoses.

Fatty acid composition of commercially manufactured omega-3 enriched pork products, haddock, and mackerel

This study was conducted to determine the commercial feasibility of feeding a 15% ground flaxseed diet to finishing hogs for up to 42 d before slaughter and to compare the fatty acid composition of the resulting pork products with commercially produced haddock and mackerel. Eighty-seven pigs were fed a control diet (predominantly corn, soybean meal-based) and then a similar diet containing 15% flaxseed for the last 28 (FS28) or 42 d (FS42) before slaughter. Control pigs were continued on the control diet (CO28 and CO42). Percentages of saturated and monounsaturated fatty acids were decreased (P < .0001), and percentages of polyunsaturated fatty acids, most prominently alpha-linolenic acid [18:3(n-3)] and the sum of all (sigma) measured (n-3) fatty acids, were increased (P < .0001) in all pork tissues (backfat, liver, and longissimus thoracis) and products (lard, muffins, Braunschweiger, and bacon) due to dietary flaxseed. The percentage of arachidonic acid [20:4(n-6)] decreased in FS28 compared to CO28 liver (P < .0001) and in longissimus thoracis polar fraction FS42 compared to CO42. The percentage of 18:3(n-3) was similar in mackerel, CO bacon, and CO longissimus thoracis, and the percentage of 18:3(n-3) and sigma(n-3) in haddock was similar to that in FS bacon and FS longissimus thoracis. The percentage of 20:5 in FS42 longissimus thoracis, polar fraction, approached the level in haddock, but the percentages of 20:5 and 22:6 were greater (P < .0001) in mackerel than in haddock. The percentage of sigma(n-3) was greater (P < .0001) in mackerel than in haddock and sigma(n-6) was greater (P < .0001) in haddock than in mackerel. Commercial production of omega-3 enriched pork products can provide consumers a feasible alternative to a diet higher in fish than that normally consumed.

Treatment of chronic hepatitis C with interferon alfa-n3: a multicenter, randomized, open-label trial

We studied the antiviral effectiveness and safety of interferon alfa-n3, a natural alpha interferon which contains multiple interferon species, in the treatment of previously untreated patients with chronic hepatitis C. Seventy-seven patients were randomized to receive either 1.0, 2.5, 5.0, or 10.0 million units (MU) of interferon alfa-n3 three times a week for 24 weeks and were then followed for an additional 24 weeks. At the end of therapy, 67% of patients in the 10 MU group normalized serum alanine transaminase (ALT) levels and 59% had no hepatitis C virus (HCV) RNA detected by polymerase chain reaction. At the end of the follow-up period, 44% of patients in the 10 MU group maintained normal ALT, and 24% had nondetectable HCV RNA. Lower doses were much less effective. Interferon alfa-n3 was well tolerated and no patient developed neutralizing anti-interferon antibodies during or after the treatment period. Interferon alfa-n3 appears to be effective against hepatitis C virus and deserves further study in larger randomized controlled trials.

Gastric vascular ectases

Gastric vascular ectases are being increasingly recognized as a significant source of acute and chronic upper gastrointestinal bleeding. Upper gastrointestinal endoscopy has not only facilitated the identification of gastric vascular ectases but has also revolutionized their therapy. This article reviews recent developments with reference to the epidemiology, diagnosis, pathogenesis, and therapy of gastric vascular ectases.

Multicenter trial of octreotide in patients with refractory acquired immunodeficiency syndrome-associated diarrhea

BACKGROUND/AIMS

Diarrhea is a significant problem in patients with acquired immunodeficiency syndrome (AIDS). The aim of this study was to determine octreotide effectiveness in refractory AIDS-associated diarrhea.

METHODS

In a 3-week protocol, 129 patients with a stool weight of > 500 g/day despite standard antidiarrheal therapy were randomized to receive octreotide or placebo (3:2 ratio). Octreotide dose was increased 100 micrograms weekly to a maximum of 300 micrograms three times a day based on weekly 72-hour stool collections. Subsequently, patients received open-label octreotide at doses of up to 500 micrograms three times a day.

RESULTS

A 30% decrease in stool weight defined response. After 3 weeks, 48% of octreotide- and 39% of placebo-treated patients had responded (P = 0.43). At 300 micrograms three times a day, 50% of octreotide- and 30.1% of placebo-treated patients responded (P = 0.12). At a baseline stool weight of 1000-2000 g/day, 57% of octreotide- and 25% of placebo-treated patients responded (P = 0.06). Response rates based on CD4 counts, diarrhea duration, body weight, human immunodeficiency virus risk factor, and presence or absence of pathogens showed no benefit of octreotide. Adverse events were more frequent in the octreotide-treated group.

CONCLUSION

In the doses studied, octreotide was not more effective than placebo in patients with refractory AIDS-associated diarrhea. This lack of effectiveness may be attributable to inadequate sample size, doses, and duration of study treatment.

Clostridium difficile-associated diarrhea in patients with HIV positivity and AIDS: a prospective controlled study

OBJECTIVE

To compare the clinical manifestations and therapeutic responses of Clostridium difficile infection in HIV-infected and noninfected individuals.

METHODS

Patients were identified for this study if they had C. difficile toxin in the stool. The patients were then followed prospectively by the investigators. All patients were treated with a standard regimen, and clinical and laboratory findings were recorded. Persistence and resolution or recurrence of symptoms and complications were recorded.

RESULTS

A total of 87 patients were studied, of which 12 were HIV positive, 20 had AIDS, and 55 had no known HIV infection. The AIDS group was younger and had a lower total leukocyte count than the controls. There were no statistically significant differences in temperature, leukocytosis, clinical symptoms, therapeutic response, or recurrence or persistent of symptoms.

CONCLUSIONS

Despite the immunosuppression of HIV infection, C. difficile infection behaves no differently in HIV/AIDS patients than it does in controls.

Differences in release of tumor necrosis factor from THP-1 cells stimulated by filtrates of antibiotic-killed Escherichia coli

Bacterial products, such as endotoxin, activate mononuclear cells to produce tumor necrosis factor (TNF) and other monokines capable of producing host cell injury. THP-1 cell TNF release in response to bacterial products generated during antibiotic killing of Escherichia coli (ATCC 12014) was evaluated. THP-1 is a mature monocytic leukemia cell line that produces TNF in a dose-dependent fashion in response to purified endotoxin. E. coli were incubated in the presence of amikacin, ciprofloxacin, ceftazidime, cefotaxime, aztreonam, or imipenem at concentrations that killed greater than 99.9% of the organisms. Aliquots of these antibiotic-bacterial cultures were added to THP-1 cells, and TNF concentrations were determined by specific immunoassay. Amikacin and imipenem produced rapid bacterial killing and were associated with low TNF levels. Ceftazidime, aztreonam, and cefotaxime killed E. coli at a slower rate and were associated with significant increases in mononuclear cell TNF responses. Ciprofloxacin produced intermediate TNF levels. Differences exist among bactericidal antibodies in their ability to generate products capable of stimulating mononuclear cell TNF release.

Endoscopic sphincterotomy: a reappraisal

Endoscopic sphincterotomy is the procedure of choice for choleducolithiasis post-cholecystectomy, and in poor-surgical-risk patients with the gallbladder still present. Sphincterotomy indications have been expanded to include acute biliary pancreatitis, acute cholangitis, and choleducolithiasis removal prior to definitive surgery. This paper will review the available literature and make recommendations on these new indications.

The antigastrolesive activity of rioprostil, a 16-methyl prostaglandin-E1 analogue in healthy volunteers

The antigastrolesive activity of rioprostil, an orally effective synthetic 16-methyl analogue of prostaglandin-E1, with potent antisecretory and antigastrolesive properties in animals, is evaluated in a series of studies involving 166 healthy male volunteers. Three double-blind, randomized, parallel, placebo-controlled studies are conducted independently at three study centres. In two studies the protective effect of rioprostil against endoscopically-demonstrated mucosal changes caused by concurrent administration of aspirin is examined. The third study evaluates the inhibitory effect of rioprostil on faecal blood loss produced by co-administration of aspirin. Oral doses of rioprostil give significant dose-dependent protection against aspirin-induced mucosal changes. The total mucosal scores at day 3 and day 11 are significantly lower in each of the rioprostil + aspirin groups compared with the aspirin treated group. The total mucosal scores generally decrease with increasing rioprostil dose. Daily faecal blood loss is significantly lower in each of the groups of subjects treated with rioprostil + aspirin, compared with those treated with aspirin + placebo. This study shows that rioprostil provides significant protection against mucosal damage caused by high doses of concomitantly administered aspirin.

Peliosis hepatis in a patient with marasmus

Peliosis hepatitis is a rare disorder previously seen in tuberculosis and malignant disorders and now seen with anabolic steroid use or after renal transplantation. We report the first case of peliosis hepatis in a patient with marasmus and no previously reported predisposing condition. Of interest, the peliosis hepatis resolved rapidly (over 2-3 wk) as determined by computed tomography scan and the patient presented with a cholestatic enzyme pattern that resolved with development of the lesion.

Effects of therapeutic paracentesis on systemic and hepatic hemodynamics and on renal and hormonal function

Thirteen patients with cirrhosis and tense ascites (six with and seven without peripheral edema) underwent 4- to 15-liter paracentesis without intravenous "colloid" replacement. Cardiac output increased from 6.6 +/- 0.7 liters per min at baseline to 8.2 +/- 0.7 liters per min (p less than 0.003) 1 hr after large-volume paracentesis completion and fell to 7.5 +/- 0.69 liters per min (p less than 0.05 vs. baseline, p less than 0.02 vs. 1 hr) 24 hr after large-volume paracentesis completion. There was no change in mean arterial pressure or mean pulmonary artery pressure. Central venous pressure fell from 9.1 +/- 0.8 mm Hg at baseline to 8.6 +/- 1.4 mm Hg 1 hr post-large-volume paracentesis to 6.8 +/- 1.0 mm Hg (p less than 0.005 vs. baseline, p less than 0.02 vs. 1 hr value) at 24 hr, and pulmonary capillary wedge pressure fell from 13.1 +/- 0.9 to 11.1 +/- 1.3 mm Hg 1 hr after large-volume paracentesis and to 9.89 +/- 1.2 (p less than 0.01 vs. baseline, p less than 0.03 vs. 1 hr after large-volume paracentesis) at 24 hr. Heart rate fell from 90 +/- 3.0 to 85 +/- 2.9 beats per min (p less than 0.01) 1 hr after large-volume paracentesis completion, but increased to 89 +/- 2.5 beats per min (p less than 0.02 vs. 1 hr after large-volume paracentesis) at 24 hr.(ABSTRACT TRUNCATED AT 250 WORDS)