A modified scoring system to describe gross pathology in the rabbit model of tuberculosis

<p>Abstract</p> <p>Background</p> <p>The rabbit model is an ideal means to study the pathogenesis of tuberculosis due to its semblance to the disease in humans. We have previously described the results using a bronchoscopic route of infection with live bacilli as a reliable means of generating lung cavities in sensitized rabbits. The role of sensitization in the development of disease outcomes has been well established in several animal models. We have described here the varying gross pathology that result from lack of sensitization with heat-killed <it>M. bovis </it>prior to high-dose bronchoscopic infection with live bacilli.</p> <p>Results</p> <p>Rabbits lacking sensitization did not generate lung cavities, but instead formed solely a tuberculoid pneumonia that replaced the normal lung parenchyma in the area of infection. Extrapulmonary dissemination was seen in approximately equal frequency and distribution in both rabbit populations. Notable differences include the lack of intestinal lesions in non-sensitized rabbits likely due to the lack of ingestion of expectorated bacilli from cavitary lesions. The experiment also employed a modified scoring system developed initially in the primate model of tuberculosis to allow for the quantification of findings observed at necropsy.</p> <p>Conclusions</p> <p>To date, no such scoring system has been employed in the rabbit model to describe gross pathology. The quantitative methodology would allow for rapid comparative analyses and standardization of thoracic and extrapulmonary pathology that could be evaluated for statistical significance. The aim is to use such a scoring system as the foundation for all future rabbit studies describing gross pathology at all stages in TB pathogenesis.</p

13[C]-Urea Breath Test as a Novel Point-of-Care Biomarker for Tuberculosis Treatment and Diagnosis

BACKGROUND: Pathogen-specific metabolic pathways may be detected by breath tests based on introduction of stable isotopically-labeled substrates and detection of labeled products in exhaled breath using portable infrared spectrometers. METHODOLOGY/PRINCIPAL FINDINGS: We tested whether mycobacterial urease activity could be utilized in such a breath test format as the basis of a novel biomarker and diagnostic for pulmonary TB. Sensitized New-Zealand White Rabbits underwent bronchoscopic infection with either Mycobacterium bovis or Mycobacterium tuberculosis. Rabbits were treated with 25 mg/kg of isoniazid (INH) approximately 2 months after infection when significant cavitary lung pathology was present. [(13)C] urea was instilled directly into the lungs of intubated rabbits at selected time points, exhaled air samples analyzed, and the kinetics of delta(13)CO(2) formation were determined. Samples obtained prior to inoculation served as control samples for background (13)CO(2) conversion in the rabbit model. (13)CO(2), from metabolic conversion of [(13)C]-urea by mycobacterial urease activity, was readily detectable in the exhaled breath of infected rabbits within 15 minutes of administration. Analyses showed a rapid increase in the rate of (13)CO(2) formation both early in disease and prior to treatment with INH. Following INH treatment, all evaluable rabbits showed a decrease in the rate of (13)CO(2) formation. CONCLUSIONS/SIGNIFICANCE: Urea breath testing may provide a useful diagnostic and biomarker assay for tuberculosis and for treatment response. Future work will test specificity for M. tuberculosis using lung-targeted dry powder inhalation formulations, combined with co-administering oral urease inhibitors together with a saturating oral dose of unlabeled urea, which would prevent the delta(13)CO(2) signal from urease-positive gastrointestinal organisms

Hyperoxemia and excess oxygen use in early acute respiratory distress syndrome : Insights from the LUNG SAFE study

Publisher Copyright: © 2020 The Author(s). Copyright: Copyright 2020 Elsevier B.V., All rights reserved.Background: Concerns exist regarding the prevalence and impact of unnecessary oxygen use in patients with acute respiratory distress syndrome (ARDS). We examined this issue in patients with ARDS enrolled in the Large observational study to UNderstand the Global impact of Severe Acute respiratory FailurE (LUNG SAFE) study. Methods: In this secondary analysis of the LUNG SAFE study, we wished to determine the prevalence and the outcomes associated with hyperoxemia on day 1, sustained hyperoxemia, and excessive oxygen use in patients with early ARDS. Patients who fulfilled criteria of ARDS on day 1 and day 2 of acute hypoxemic respiratory failure were categorized based on the presence of hyperoxemia (PaO2 > 100 mmHg) on day 1, sustained (i.e., present on day 1 and day 2) hyperoxemia, or excessive oxygen use (FIO2 ≥ 0.60 during hyperoxemia). Results: Of 2005 patients that met the inclusion criteria, 131 (6.5%) were hypoxemic (PaO2 < 55 mmHg), 607 (30%) had hyperoxemia on day 1, and 250 (12%) had sustained hyperoxemia. Excess FIO2 use occurred in 400 (66%) out of 607 patients with hyperoxemia. Excess FIO2 use decreased from day 1 to day 2 of ARDS, with most hyperoxemic patients on day 2 receiving relatively low FIO2. Multivariate analyses found no independent relationship between day 1 hyperoxemia, sustained hyperoxemia, or excess FIO2 use and adverse clinical outcomes. Mortality was 42% in patients with excess FIO2 use, compared to 39% in a propensity-matched sample of normoxemic (PaO2 55-100 mmHg) patients (P = 0.47). Conclusions: Hyperoxemia and excess oxygen use are both prevalent in early ARDS but are most often non-sustained. No relationship was found between hyperoxemia or excessive oxygen use and patient outcome in this cohort. Trial registration: LUNG-SAFE is registered with ClinicalTrials.gov, NCT02010073publishersversionPeer reviewe

Continued Deficits of the Perceived Harms of Cigarette Smoking Among Young Adults: Insights from Participants on Amazon Mechanical Turk

Young adults are an age group that has been the target of multiple education campaigns regarding the harms of cigarette smoke exposure. Although smoking rates of conventional cigarettes have declined in the US, continued usage is noted among a select subset of the population aged 18 –30 years. This group either serves as current or soon-to-be future caretakers of young children who will likely spend a significant amount of time exposed to their cigarette byproducts. Understanding their current knowledge base of the dangers of secondhand smoke and the means to address these risks are of major importance for the welfare of young children. We had utilized a brief and limited sample size survey to explore the utility of using an online task marketplace on Amazon.com® to assess secondhand smoking beliefs and financial incentives among young adults. The pilot study had a particular focus on the perception and means to minimize smoke exposure among children residing with young adults serving as their primary caretaker or fellow home residents.</p

Linkage of Maternal Caregiver Smoking Behaviors on Environmental and Clinical Outcomes of Children with Asthma: A Post-Hoc Analysis of a Financial Incentive Trial Targeting Reduction in Pediatric Tobacco Smoke Exposures

(1) Background: Monthly variability in smoking behaviors in caregivers of pediatric asthmatics yields questions of how much and when does smoking reduction result in improved environmental and clinical outcomes. (2) Methods: Post hoc analysis of data from a 6 month pilot randomized-control trial occurring from May 2017 to May 2018 in Baltimore City (MD, USA). The initial trial&rsquo;s primary intervention explored the utility of financial incentives in modifying caregiver smoking behaviors. Post hoc analyses examined all dyads independent of the initial trial&rsquo;s randomization status. All caregivers received pediatric tobacco smoke harm reduction education, in addition to monthly encouragement to access the state tobacco quitline for individual phone-based counseling and nicotine replacement therapy. Maternal caregivers who were active cigarette smokers and their linked asthmatic child (aged 2&ndash;12 years) were grouped into two classifications (&ldquo;high&rdquo; versus &ldquo;low&rdquo;) based on the child and caregiver&rsquo;s cotinine levels. A &ldquo;low&rdquo; cotinine level was designated by at least a 25% reduction in cotinine levels during 3 months of the trial period; achieving &le;2 months of low cotinine levels defaulted to the &ldquo;high&rdquo; category. Twenty-seven dyads (caregivers and children) (total n = 54) were assigned to the &ldquo;high&rdquo; category, and eighteen dyads (caregivers and children) (total n = 36) were allocated to the &ldquo;low&rdquo; category. The primary outcome measure was the correlation of caregiver cotinine levels with pediatric cotinine values. Secondary outcomes included asthma control, in addition to caregiver anxiety and depression. (3) Results: Caregivers with 3 months of &ge;25% decrease in cotinine levels had a significantly greater mean change in child cotinine levels (p = 0.018). &ldquo;Low&rdquo; caregiver cotinine levels did not significantly improve pediatric asthma control (OR 2.12 (95% CI: 0.62&ndash;7.25)). Caregiver anxiety and depression outcomes, measured by Patient Health Questionnaire (PHQ)-4 scores, was not significantly different based on cotinine categorization (p = 0.079); (4) Conclusion: Reduced pediatric cotinine levels were seen in caregivers who reduced their smoking for at least 3 months, but clinical outcome measures remained unchanged