Excessive airway obstruction is the cause of symptoms and abnormal lung function in asthma.As airway smooth muscle (ASM) is the effecter controlling airway calibre, it is suspected that dysfunction of ASM contributes to the pathophysiology of asthma. However, the precise role of ASM in the series of events leading to asthmatic symptoms is not clear. It is not certain whether, in asthma, there is a change in the intrinsic properties of ASM, a change in the structure and mechanical properties of the noncontractile components of the airway wall, or a change in the interdependence of the airway wall with the surrounding lung parenchyma. All these potential changes could result from acute or chronic airway inflammation and associated tissue repair and remodelling.Anti-inflammatory therapy, however, does not “cure” asthma, and airway hyperresponsiveness can persist in asthmatics, even in the absence of airway inflammation. This is perhaps because the therapy does not directly address a fundamental abnormality of asthma, that of exaggerated airway narrowing due to excessive shortening of ASM.In the present study, a central role for airway smooth muscle in the pathogenesis of airway hyperresponsiveness in asthma is explored.

Granulocyte-macrophage colony-stimulating factor (GM-CSF) stimulates hemopoiesis and effector functions of granulocytes and macrophages and is involved in pulmonary surfactant homeostasis. We investigated whether GM-CSF therapy improved clinically diagnosed severe sepsis and respiratory dysfunction in critically ill patients. This randomized, double-blind, placebo-controlled phase II study added low-dose (3 mcg/kg) intravenous recombinant human GM-CSF daily for 5 days to conventional therapy in 10 patients, with a further eight patients receiving placebo. GM-CSF–treated patients showed improvement in PaO₂/Fi O₂ over 5 days (p = 0.02) and increased peripheral blood neutrophils (p = 0.08), whereas alveolar neutrophils decreased (p = 0.02). GM-CSF therapy was not associated with decreased 30-day survival or with increased acute respiratory distress syndrome or extrapulmonary organ dysfunction. GM-CSF therapy was associated with increased blood granulocyte superoxide production and restoration or preservation of blood and alveolar leukocyte phagocytic function. We conclude that low-dose GM-CSF was associated with improved gas exchange without pulmonary neutrophil infiltration, despite functional activation of both circulating neutrophils and pulmonary phagocytes. In addition, GM-CSF therapy was not associated with worsened acute respiratory distress syndrome or the multiple organ dysfunction syndrome, suggesting a homeostatic role for GM-CSF in sepsis-related pulmonary dysfunction.

Background: The refractive index (RI) of cellular material provides fundamental biophysical information about the composition and organizational structure of cells. Efforts to describe the refractive properties of cells have been significantly impeded by the experimental difficulties encountered in measuring viable cell RI. In this report we describe a procedure for the application of quantitative phase microscopy in conjunction with confocal microscopy to measure the RI of a cultured muscle cell specimen.Methods: The experimental strategy involved calculation of cell thickness by using confocal optical sectioning procedures, construction of a phase map of the same cell using quantitative phase microscopy, and selection of cellular regions of interest to solve for the cell RI.Results: Mean cell thickness and phase values for six cell regions (five cytoplasmic and one nuclear) were determined. The average refractive index calculated for cytoplasmic and nuclear regions was 1.360 ± 0.004. The uncertainty in the final RI value represents the technique measurement error.Conclusions: The methodology we describe for viable cell RI measurement with this prototype cell has broad generic application in the study of cell growth and functional responses. The RI value we report may be used in optical analyses of cultured cell structure and morphology.

Coal workers’ pneumoconiosis (CWP), as part of the spectrum of coal mine dust lung disease (CMDLD), is a preventable but incurable lung disease that can be complicated by respiratory failure and death. Recent increases in coal production from the financial incentive of economic growth lead to higher respirable coal and quartz dust levels, often associated with mechanization of longwall coal mining. In Australia, the observed increase in the number of new CWP diagnoses since the year 2000 has necessitated a review of recommended respirable dust exposure limits, where exposure limits and monitoring protocols should ideally be standardized. Evidence that considers the regulation of engineering dust controls in the mines is lacking even in high‐income countries, despite this being the primary preventative measure. Also, it is a global public health priority for at‐risk miners to be systemically screened to detect early changes of CWP and to include confirmed patients within a central registry; a task limited by financial constraints in less developed countries. Characteristic X‐ray changes are usually categorized using the International Labour Office classification, although future evaluation by low‐dose HRCT) chest scanning may allow for CWP detection and thus avoidance of further exposure, at an earlier stage. Preclinical animal and human organoid‐based models are required to explore potential re‐purposing of anti‐fibrotic and related agents with potential efficacy. Epidemiological patterns and the assessment of molecular and genetic biomarkers may further enhance our capacity to identify susceptible individuals to the inhalation of coal dust in the modern era.