Tolerability and pharmacokinetics of intravenous allopregnanolone with and without midazolam pretreatment in two healthy dogs.

The neurosteroid allopregnanolone (ALLO) is under investigation as a treatment for benzodiazepine-refractory status epilepticus (SE). Here, we assess the cardiopulmonary safety of intravenous ALLO by itself and after a clinically recommended dose of midazolam (MDZ) in two healthy adult beagles. Each dog received ALLO (1 mg/kg, IV), and after a washout period of 2 weeks, each dog was dosed with MDZ (0.2 mg/kg, IV) followed 10 minutes later by ALLO. Behavioral state, vital signs, arterial blood gases, blood chemistries, and plasma ALLO concentrations were monitored for up to 6 hours after dosing. The dogs appeared sleepy but were fully responsive after both treatments. No depression of mean arterial pressure or respiratory rate was noted. Blood gas measurements failed to show evidence of drug-induced acute respiratory acidosis. Estimated maximum plasma ALLO concentrations were in the range of 1500 to 3000 ng/ml. The results indicate that intravenous ALLO can be used safely to treat benzodiazepine-refractory SE, even when administered shortly after a benzodiazepine.

Differential pulmonary effects of wintertime California and China particulate matter in healthy young mice.

Airborne particulate matter (PM) is associated with adverse cardiorespiratory effects. To better understand source-orientated PM toxicity, a comparative study of the biological effects of fine PM (diameter≤2.5µm, PM2.5) collected during the winter season from Shanxi Province, China, and the Central Valley, California, United States, was conducted. The overarching hypothesis for this study was to test whether the chemical composition of PM on an equal mass basis from two urban areas, one in China and one in California, can lead to significantly different effects of acute toxicity and inflammation in the lungs of healthy young mice. Male, 8-week old BALB/C mice received a single 50µg dose of vehicle, Taiyuan PM or Sacramento PM by oropharyngeal aspiration and were sacrificed 24h later. Bronchoalveolar lavage, ELISA and histopathology were performed along with chemical analysis of PM composition. Sacramento PM had a greater proportion of oxidized organic material, significantly increased neutrophil numbers and elevated CXCL-1 and TNF-α protein levels compared to the Taiyuan PM. The findings suggest that Sacramento PM2.5 was associated with a greater inflammatory response compared to that of Taiyuan PM2.5 that may be due to a higher oxidice. Male, 8-week old BALB/C mice received a single 50µg dose of vehicle, Taiyuan PM or Sacramento PM by oropharyngeal aspiration and were sacrificed 24h later. Bronchoalveolar lavage, ELISA and histopathology were performed along with chemical analysis of PM composition. Sacramento PM had a greater proportion of oxidized organic material, significantly increased neutrophil numbers and elevated CXCL-1 and TNF-α protein levels compared to the Taiyuan PM. The findings suggest that Sacramento PM2.5 was associated with a greater inflammatory response compared to that of Taiyuan PM2.5 that may be due to a higher oxidized state of organic carbon and copper content.

Soot and house dust mite allergen cause eosinophilic laryngitis in an animal model.

OBJECTIVES/HYPOTHESIS: Chronic laryngitis (CL) is common and costly. One of the most common causes of CL is thought to be laryngopharyngeal reflux, although a significant percentage of individuals fail to get better with acid suppressive therapy. The role of other potential causes of CL such as allergy and environmental pollution has not been thoroughly investigated. PURPOSE: To evaluate the association between iron soot, house dust mite allergen (HDMA), and CL in an established animal model. METHODS: Twenty-four guinea pigs were separated into four 6-week exposure groups: 1) saline (allergen control) + filtered air (pollution control); 2) HDMA (Dermatophygoides farinae) + filtered air; 3) saline + combustion particulates; or 4) HDMA + combustion particulates. The primary outcome measure was mean eosinophil profile (MEP) in glottic, subglottic, and trachea epithelium and submucosa. RESULTS: The combination of iron soot and HDMA caused eosinophilia (elevated MEP) in the glottic (P < 0.06), subglottic (P < 0.05), and trachea (P < 0.05) submucosa and epithelium (P < 0.05). CONCLUSION: The combination of HDMA and iron soot resulted in laryngeal eosinophilia in an established guinea pig model of CL. The data support the notion that factors other than reflux may cause CL. Further investigation into eosinophilic laryngitis as a distinct clinical entity caused by exposure to environmental allergen and pollution is warranted.

Women and Lung Disease. Sex Differences and Global Health Disparities.

There is growing evidence that a number of pulmonary diseases affect women differently and with a greater degree of severity than men. The causes for such sex disparity is the focus of this Blue Conference Perspective review, which explores basic cellular and molecular mechanisms, life stages, and clinical outcomes based on environmental, sociocultural, occupational, and infectious scenarios, as well as medical health beliefs. Owing to the breadth of issues related to women and lung disease, we present examples of both basic and clinical concepts that may be the cause for pulmonary disease disparity in women. These examples include those diseases that predominantly affect women, as well as the rising incidence among women for diseases traditionally occurring in men, such as chronic obstructive pulmonary disease. Sociocultural implications of pulmonary disease attributable to biomass burning and infectious diseases among women in low- to middle-income countries are reviewed, as are disparities in respiratory health among sexual minority women in high-income countries. The implications of the use of complementary and alternative medicine by women to influence respiratory disease are examined, and future directions for research on women and respiratory health are provided.

Susceptibility of the aging lung to environmental injury.

With an ever-increasing number of elderly individuals in the world, a better understanding of the issues associated with aging and the environment is needed. The respiratory system is one of the primary interfaces between the body and the external environment. An expanding number of studies suggest that the aging pulmonary system (>65 years) is at increased risk for adverse health effects from environmental insult, such as by air pollutants, infection, and climate change. However, the mechanism(s) for increased susceptibility in this subpopulation are not well understood. In this review, we provide a limited but comprehensive overview of how the lung ages, examples of environmental exposures associated with injury to the aging lung, and potential mechanisms underlying the increased vulnerability of the aging lung to injury from environmental factors.

Asthma/allergic airways disease: does postnatal exposure to environmental toxicants promote airway pathobiology?

UNLABELLED: The recent, dramatic increase in the incidence of childhood asthma suggests a role for environmental contaminants in the promotion of interactions between allergens and the respiratory system of young children. To establish whether exposure to an environmental stressor, ozone (O3), and an allergen, house dust mite (HDMA), during early childhood promotes remodeling of the epithelial-mesenchymal trophic unit (EMTU) of the tracheobronchial airway wall by altering postnatal development, infant rhesus monkeys were exposed to cyclic episodes of filtered air (FA), HDMA, O3, or HDMA plus O3. The following alterations in the EMTU were found after exposure to HDMA, O3, or HDMA plus O3: (1) reduced airway number; (2) hyperplasia of bronchial epithelium; (3) increased mucous cells; (4) shifts in distal airway smooth muscle bundle orientation and abundance to favor hyperreactivity; (5) interrupted postnatal basement membrane zone differentiation; (6) modified epithelial nerve fiber distribution; and (7) reorganization of the airway vascular and immune system. CONCLUSIONS: cyclic challenge of infants to toxic stress during postnatal lung development modifies the EMTU. This exacerbates the allergen response to favor development of intermittent airway obstruction associated with wheeze. And, exposure of infants during early postnatal lung development initiates compromises in airway growth and development that persist or worsen as growth continues, even with cessation of exposure.

Early postnatal exposure to allergen and ozone leads to hyperinnervation of the pulmonary epithelium.

Airway injury in infant monkeys exposed to ozone and/or house dust mite allergen (HDMA) is associated with a loss of epithelial innervation. In this study, we evaluated for persistence/recovery of the altered epithelial innervation. Thirty-day-old rhesus monkeys were exposed to repeated episodes of HDMA and/or ozone from 1 to 6 months of age and subsequently allowed to recover for 6 months in the absence of further ozone exposure and/or minimal HDMA challenge (sufficient to maintain allergen sensitization). At 1 year of age, nerve density in intrapulmonary airways was immunohistochemically evaluated using antibodies directed against protein gene product 9.5. Hyperinnervation and irregular epithelial nerve distribution was observed in both HDMA- and ozone-exposed groups; most prominent alterations were observed in animals exposed to HDMA plus ozone. Therefore, while adaptive mechanisms exist that re-establish epithelial innervation following cessation or diminution of exposure to HDMA and/or ozone, the recovery is associated with persistent proliferative mechanisms that result in hyperinnervation of the airways.

Temporal and spatial distribution of ciliogenesis in the tracheobronchial airways of mice.

Little is known about ciliogenesis as it proceeds through the entire airway tree, from the trachea to the terminal bronchioles, especially during the postnatal period. The purpose of this study was to define the spatial and temporal (prenatal and postnatal) pattern of normal cilia development in the mouse. Three airway generations representing the entire airway tree were examined: trachea, lobar bronchi, and terminal bronchiole. Ciliated cells in lung lobe whole mounts were labeled with a fluorescent dye for confocal microscopy, and ciliated cell surface density was measured for each airway generation and age. The same samples were examined by scanning electron microscopy to verify the appearance of ciliated cells among the differentiating epithelium of the airways. Ciliated cells were first detected in the trachea and lobar bronchi at 16 days gestational age (DGA) and in the terminal bronchioles at 18 DGA. Ciliated cell surface density increased with prenatal and postnatal age at all airway levels. However, the ciliated cell surface density of the trachea and lobar bronchi was always greater compared with the terminal bronchiole. In conclusion, the study revealed that in developing tracheobronchial airways of the mouse: 1) Ciliogenesis differs temporally and spatially by airway generation; 2) Ciliated cell surface density increases with age in all airway generations, but density decreases in a proximal to distal direction; and 3) A significant portion of ciliogenesis continues after birth. This study provides a healthy basis for investigations of neonatal pulmonary disease or pollutant toxicity affecting cilia and its functions.

Smooth muscle development during postnatal growth of distal bronchioles in infant rhesus monkeys.

Development of smooth muscle in conducting airways begins early in fetal life. Whereas the pattern and regulation of smooth muscle differentiation are well-defined, the impact of airway growth on the process is not. To evaluate the transformations in organization during postnatal growth, smooth muscle bundle organization (size, abundance, and orientation) was mapped in five generations of distal airways of infant rhesus monkeys (5 days and 1, 2, 3, and 6 mo old). On the basis of direct measurement of the bronchiole proximal to the terminal bronchiole, length increased by 2-fold, diameter by 1.35-fold, and surface area by 2.8-fold between 5 days and 6 mo of age. Smooth muscle bundle size was greater in proximal bronchioles than in respiratory bronchioles and did not change with age. However, relative bundle size decreased in proportion to airway size as the airways grew. Relative bundle abundance was constant regardless of airway generation or age. The distribution of smooth muscle bundle orientation changed with age in each airway generation, and there were significant changes in the terminal and respiratory bronchioles. We conclude that smooth muscle undergoes marked organizational changes as airways grow during postnatal development.

Proliferation during early phases of bronchiolar repair in neonatal rabbits following lung injury by 4-ipomeanol.

Nonciliated bronchiolar (Clara cells) are progenitor cells during development. During differentiation, they are more susceptible to injury by environmental toxicants metabolized by the cytochrome P450 monooxygenase system, and injury results in altered bronchiolar repair and development. Squamous cells and abnormal cuboidal epithelium persist into early adulthood. The hypothesis tested in this study was that the failure of bronchiolar epithelium to repair normally in neonates following injury is due to an inhibition of proliferation. A model of differential repair in rabbit kits was used. Proliferation was followed for 1 week post injury in rabbit kits treated with a single dose of the P450-mediated cytotoxicant 4-ipomeanol (IPO) at 7 days old (repair abnormal) and compared to rabbits treated with a single dose of IPO at 21 days old (repair normal). Proliferation was measured by the nuclear incorporation of 5-chloro-2'-deoxyuridine (CldU) within epithelium at the target site (terminal bronchiole). The repair pattern between the two age groups was histologically defined. There was no difference in the CldU labeling index during the week of repair between the two age groups, even though the bronchiolar epithelium did not return to normal in the animals treated at 7 days old. In summary, proliferation (through S-phase) is not inhibited during repair in neonatal rabbits treated with IPO at 7 days old compared to animals treated at 21 days old, and we conclude that other factors may be responsible for the altered repair in the young neonates injured by a P450-mediated cytotoxicant.