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Comparative analysis of realistic CT-scan and simplified human airway models in airflow simulation

Johari NH, Osman K, Helmi NH, Abdul Kadir MA

Comput Methods Biomech Biomed Engin, 2015;18(1):48-56.
PMID: 23521065 DOI: 10.1080/10255842.2013.776548

Efforts to model the human upper respiratory system have undergone many phases. Geometrical proximity to the realistic shape has been the subject of many research projects. In this study, three different geometries of the trachea and main bronchus were modelled, which were reconstructed from computed tomography (CT) scan images. The geometrical variations were named realistic, simplified and oversimplified. Realistic refers to the lifelike image taken from digital imaging and communications in medicine format CT scan images, simplified refers to the reconstructed image based on natural images without realistic details pertaining to the rough surfaces, and oversimplified describes the straight wall geometry of the airway. The characteristics of steady state flows with different flow rates were investigated, simulating three varied physical activities and passing through each model. The results agree with previous studies where simplified models are sufficient for providing comparable results for airflow in human airways. This work further suggests that, under most exercise conditions, the idealised oversimplified model is not favourable for simulating either airflow regimes or airflow with particle depositions. However, in terms of immediate analysis for the prediction of abnormalities of various dimensions of human airways, the oversimplified techniques may be used.

Matched MeSH terms: Bronchi/physiology
Cyclic adenosine 3',5'-monophosphate content and bronchial smooth muscle contractility of hyper- and hypothyroid lungs

Nabishah BM, Morat PB, Alias AK, Kadir BA, Khalid BA

Clin Exp Pharmacol Physiol, 1992 Dec;19(12):839-42.
PMID: 1335381

1. Male Sprague-Dawley rats were made either hyper- or hypothyroid with thyroxine or 4-methyl-2-thiouracil, respectively. Bronchial smooth muscle (BSM) contractility and lung cyclic adenosine 3',5'-monophosphate (cAMP) content were measured in both conditions. 2. Bronchial smooth muscle contractility was significantly weaker in hyperthyroid rats, while the BSM contractility of hypothyroid rats was the same as controls. 3. The cAMP content of hyperthyroid rat lungs was similar to controls but was decreased in hypothyroid rats. 4. These studies demonstrated that both the hyper- and hypothyroid states affect respiration, although the mechanisms involved with different for each condition.

Matched MeSH terms: Bronchi/physiology*
Analysis of airway epithelial regeneration and repair following endobronchial brush biopsy in sheep

Yahaya B, Baker A, Tennant P, Smith SH, Shaw DJ, McLachlan G, et al.

Exp. Lung Res., 2011 Nov;37(9):519-35.
PMID: 21895444 DOI: 10.3109/01902148.2011.605513

Understanding the fundamental processes involved in repairing the airway wall following injury is fundamental to understanding the way in which these processes are perturbed during disease pathology. Indeed complex diseases such as asthma and chronic obstructive pulmonary disease (COPD) have at their core evidence of airway wall remodeling processes that play a crucial functional role in these diseases. The authors sought to understand the dynamic cellular events that occur during bronchial airway epithelial repair in sheep. The injury was induced by endobronchial brush biopsy (BBr), a process that causes epithelial débridement and induces a consequential repair process. In addition, the current experimental protocol allowed for the time-dependent changes in airway wall morphology to be studied both within and between animals. The initial débridement was followed by evidence of dedifferentiation in the intact epithelium at the wound margins, followed by proliferation of cells both within the epithelium and in the deeper wall structures, notably in association with the submucosal glands and smooth muscle bundles. Seven days after injury, although the airway wall was thickened at the site of damage, the epithelial layer was intact, with evidence of redifferentiation. These studies, in demonstrating broad agreement with previous studies in small animals, indicate the wider relevance of this system as a comparative model and should provide a solid basis upon which to further characterize the critical cellular and molecular interactions that underlie both effective restitution and pathological repair.

Matched MeSH terms: Bronchi/physiology*
Effect of acetylcholine and morphine on bronchial smooth muscle contraction and its modulation by steroid hormones

Nabishah BM, Morat PB, Khalid BA, Kadir BA

Clin Exp Pharmacol Physiol, 1990 Dec;17(12):841-7.
PMID: 2092952

1. The effects of corticosteroid pretreatment on acetylcholine (ACH)-induced contraction of bronchial smooth muscle (BSM) were studied. 2. ACH dose-response curves for dexamethasone (DM)- and corticosterone (B)-treated but not deoxycorticosterone (DOC)-treated BSM were significantly shifted to the right; this provides evidence that glucocorticoid treatment reduced the sensitivity of BSM to ACH. 3. Morphine enhanced BSM contraction in response to ACH by 20%. DM suppressed this enhancement. 4. These findings correlated well with the reduction of muscarinic receptor numbers in BSM by glucocorticoids in our previous study. In addition, glucocorticoids reduced the sensitivity of BSM to opioids.

Matched MeSH terms: Bronchi/physiology
Bronchodilator effects of Lignosus rhinocerotis extract on rat isolated airways is linked to the blockage of calcium entry

Lee MK, Lim KH, Millns P, Mohankumar SK, Ng ST, Tan CS, et al.

Phytomedicine, 2018 Mar 15;42:172-179.
PMID: 29655683 DOI: 10.1016/j.phymed.2018.03.025

BACKGROUND: Lignosus rhinocerotis (Cooke) Ryvarden is a popular medicinal mushroom used for centuries in Southeast Asia to treat asthma and chronic cough. The present study aimed to investigate the effect of this mushroom on airways patency.
MATERIALS AND METHODS: The composition of L. rhinocerotis TM02 cultivar was analyzed. Organ bath experiment was employed to study the bronchodilator effect of Lignosus rhinocerotis cold water extract (CWE) on rat isolated airways. Trachea and bronchus were removed from male Sprague-Dawley rats, cut into rings of 2 mm, pre-contracted with carbachol before adding CWE into the bath in increasing concentrations. To investigate the influence of incubation time, tissues were exposed to intervals of 5, 15 and 30 min between CWE concentrations after pre-contraction with carbachol in subsequent protocol. Next, tissues were pre-incubated with CWE before the addition of different contractile agents, carbachol and 5-hydroxytrptamine (5-HT). The bronchodilator effect of CWE was compared with salmeterol and ipratropium. In order to uncover the mechanism of action of CWE, the role of beta-adrenoceptor, potassium and calcium channels was investigated.
RESULTS: Composition analysis of TM02 cultivar revealed the presence of β-glucans and derivatives of adenosine. The extract fully relaxed the trachea at 3.75 mg/ml (p 

Matched MeSH terms: Bronchi/physiology