This research focuses on investigating the vibration characteristics of branched circular cylindrical shells with applications to airway passages. Analytical modelling is carried out based on Donnell-Mushtari equations of thin elastic membrane type of shells while numerical validation is conducted using the Finite Element Method (COSMOS/Works). Further validation of the results is performed using experimental investigation of tracheobronchial tissues dissected from pigs. The analytical, numerical and experimental results are in acceptable agreement. Further investigation of the vibration characteristics of the airways for cases which cannot be dealt with analytically is carried out using COSMOS/Works. Results show a strong trend relationship which suggests that the natural frequency of the trachea and the primary tracheobronchi is approximately 10 Hz. Radial resonances of lower bronchi are predictable through trends found in this work that the resonant frequency is a linear function in certain region of generations.

[Truncated abstract] The extent to which an airway narrows is strongly influenced by mechanical loads on airway smooth muscle (ASM). This thesis considers both dynamic and static mechanical loads. Dynamic load describes the time varying load on airways produced by oscillatory breathing movements. Static load is that present at a fixed lung volume ie. without breathing. In the intact lung static load principally comprises the pressure across the airway wall, that is transmural pressure (Ptm), and elastic after-load arising from distortion of airway and lung tissue by the narrowing airway. The experiments performed in this thesis were designed to answer several outstanding questions relating to how dynamic and static loads regulate airway narrowing. Dynamic load from breathing movements cyclically stretches ASM, which produces a number of physiological and cellular effects. For example in ASM strips a period of cyclical stretch reduces subsequent ASM contraction. However the response of the whole airway to dynamic load may differ from isolated ASM where non-muscle tissue also contributes. The first aim of this thesis was to characterise the response of the whole airway to dynamic load and determine whether the airway wall modifies the effects produced by ASM length cycling. Static after-loads restrict ASM shortening providing a limit to airway narrowing. Two primary sources of airway wall load include cartilage and the mucosal membrane which contribute to airway compliance. The relative importance of cartilage and mucosa to airway wall compliance and airway narrowing is unclear. ... Results demonstrate that airway narrowing is restricted by Ptm but not by parenchymal elastic after-load. The major findings of this thesis are: (1) dynamic loads produced by breathing movements regulate airway responsiveness through cyclical airway expansion and elongation; (2) the reported effects of cyclical stretch on ASM contraction differs in situ 8 possibly due to modification by one or more biomechanical or physiological properties of the airway wall; (3) parenchymal elastic after-loads, previously thought to be important during bronchoconstriction, do not restrict airway narrowing. Given the absence of an effect of parenchymal elastic after-load on airway narrowing, the static mechanical load on ASM therefore comprises Ptm and airway wall stiffness, with important contributions from cartilage and mucosa depending on lung volume.

Diss. (sammanfattning) Stockholm : Karol. inst. / Härtill 5 uppsatser.

Thesis (PhD) -- Auckland University of Technology, 2005. / Also held in print (180 leaves, ill., 30 cm.) in Akoranga Theses Collection (T 611.2 AU)

Thesis (M.D.)--University of Hong Kong, 1992. / Includes bibliographical references (leaves 186-206).

Thesis (M.D.)--University of Hong Kong, 1992. / Includes bibliographical references (leaves 186-206) Also available in print.

Class of 2015 Abstract / Objectives: The purpose of this study is to explore potential changes in cytokine and interferon expression during co-infection of rhinovirus and Alternaria. Methods: Alternaria filtrates were used to represent Alternaria spores in real-life. The responses were assessed by production of IL-6, IL-8 and interferon, which were measured by ELISA. mRNA expression was detected by quantitative real-time PCR. For data analysis, a two-sided t-test was performed to compare individual experimental groups. Results: Co-infection of Alternaria and rhinovirus enhanced IL-6 and IL-8 production significantly (p< 0.05). However, Alternaria significantly inhibited production of interferon which would otherwise be induced by rhinovirus. Average interferon-beta (IFN β) production was reduced by about 67%; interferon-lambda (IFN λ) was decrease by about 75%. The differences between treatment and control groups were also statistically significant (p < 0.05). Conclusions: These findings suggested that the Alternaria may cause an imbalanced mucosal antiviral response through inhibiting production of interferon while enhancing production of proinflammatory cytokines. These results indicated that Alternaria may lead to inhibit host innate immunity against virus infection, causing more inflammatory response.

INTRODUCTION: Cephalometric soft tissue findings have shown correlation with pharyngeal width. Facial photographic analysis of patients with Obstructive Sleep Apnea (OSA) shows an increase in width and flatness of the midface. However, three-dimensional facial soft tissue morphology of children with OSA has not been studied. OBJECTIVE: The objective of the current study was to evaluate the association between facial morphology, upper airway volume, Polysomnography (PSG), and Pediatric Sleep Questionnaire (PSQ) findings in children with OSA versus controls. MATERIAL AND METHODS: The sample included de-identified pre-treatment Cone-beam Computed Tomography images, PSG and PSQ results of 36 children (mean age 6.8 ± 2.8) from one pediatric dental practice. Three-dimensional facial soft tissue landmarks were digitized using Mimics v.20 software. Upper airway volume was segmented into right nasal cavity (RNC), left nasal cavity (LNC), nasopharynx (NP), oropharynx (OP), and hypopharynx (HP). Apnea Hypopnea Index (AHI), Respiratory Disturbance Index (RDI) scores and Pediatric sleep questionnaire (PSQ) values were correlated with soft tissue measurements (a modified Farkas anthropometric analysis) and upper airway volumes using Pearson’s correlation. Student’s T-test was used to evaluate the difference between facial soft tissue measurements of children with obstructive sleep apnea (OSA) versus the control group. RESULTS: Experimental versus control: Polysomnography findings: Apnea/Hipopnea Index and Respiratory Disturbance Index were statistically higher in obstructive sleep apnea children compared to controls (p=<.0001, 0.0001), and lowest oxygen percentage SpO2 was significantly lower (p=0.006). Airway volume findings: Right nasal cavity was statistically larger in obstructive sleep apnea children compared to controls (p=0.04). Soft tissue findings: Exocanthus right to midsagittal plane, Exocanthus right and Exocanthus left, and Soft tissue orbitale right to midsagittal plane were smaller in obstructive sleep apnea children compared to controls (p=0.01, 0.02, 0.03). Experimental group results: Transverse. Nose: Bialar distance was positively correlated to right nasal cavity and nasopharynx, and negatively correlated to hypopharynx, Apnea/Hipopnea Index, and Respiratory Disturbance Index. Lips: Chelion Right and Left, and Crista Philtri Right and Left were positively correlated to NasoPharynx. Anteroposterior. Most of nose and lips measurements were positively correlated to Right Nasal Cavity and negatively correlated to Respiratory Disturbance Index and low oxygen percentage SpO2. Vertical. Nose measurements were positively correlated to NasoPharynx. Lips measurements were positively correlated to NasoPharynx and OroPharynx and negatively correlated to low oxygen percentage SpO2. Control group result: Transverse. Nose: Nostril Base Right to midsagittal was positively correlated to NasoPharynx and average oxygen percentage SpO2 and negatively correlated to Respiratory Disturbance Index. ProNasale to Nostril Base Right and Nostril Base Left was negatively correlate to Pediatric Sleep Questionnaire. Lips: Crista Philtri Right to midsagittal and Chelion Right to midsagittal plane were positively correlated to NasoPharynx and average oxygen percentage SpO2. Anteroposterior. Nose measurements were positively correlated to Right Nasal Cavity, NasoPharynx, OroPharynx, and HypoPharynx and negatively correlated to Pediatric Sleep Questionnaire. Lips measurements were positively correlated to Right Nasal Cavity, NasoPharynx. And OroPharynx. Vertical. Most nose and lips measurements were positively correlated to Right Nasal Cavity, NasoPharynx, OroPharynx, and HypoPharynx, and negatively correlated to Apnea/Hypopnea Index and Respiratory Disturbance Index. CONCLUSION: It can be concluded that for the experimental group wider faces at the level of the eyes, nose and lips indicated increased upper airway volumes, decreased Polysomnography, and Pediatric Sleep Questionnaire values. Moreover, more forward position of the nose and lips in relation to the coronal plane were linked to increased nasal airway volume and decreased Polysomnography values. Finally, long-faced individuals displayed higher volume of the upper airway and decreased oxygen saturation levels. In regards to the control group, anteroposterior measurements positively correlated to all airway compartments and negatively correlated to Pediatric Sleep Questionnaire values. Vertically, longer faces exhibit larger airway compartments and decreased Polysomnography values.

Craniofacial deficiencies in 3-dimensions and their relationships to airway volume have been studied in the past. Much research has investigated maxillary transverse, sagittal or vertical dimensions with correlations to airway volume. Similarly, mandibular characteristics such as its anteroposterior or vertical dimensions have been analyzed. To the author’s current knowledge, there have been limited studies which investigated the relationship between transverse dimensions of the mandible and airway volume. The objectives of our study were to investigate: 1) If there is a significant association between mandibular transverse dimensions and airway volume, mandibular anteroposterior or vertical measurements in the pediatric population. 2) If mandibular anteroposterior and vertical measurements correlated to airway volume. 3) If an OSA symptomatic group had any significant differences in mandibular morphologies, pediatric sleep questionnaire (PSQ), Apnea-hypoxia index (AHI), or Respiratory Disturbance index (RDI), compared to an asymptomatic control group in the pediatric population. This was a cohort, retrospective, correlational study comprised of 22 males, and 14 females (Mean age of 6.8 ± 2.8, range: 2 to 13 years old). Digital CBCT images were acquired from a single private pediatric practice. Utilizing Mimics v.21 analytical software, airway was measured and segmented into right nasal cavity (RNC), left nasal cavity (LNC), nasopharynx (NP), oropharynx (OP) and hypopharynx (HP). Mandibular traits in sagittal, vertical and transverse dimensions were analyzed to see if correlations exist with airway volume, PSQ, AHI, or RDI scores. Differences were also evaluated between symptomatic and asymptomatic groups. Results revealed that asymptomatic patients had significantly greater width between the right and left gonions (Trans-Go) as compared to symptomatic patients. Within each group, Trans-Go was shown to have significant positive correlations to total airway volume, corpus length and ramus height (p < 0.05). There are significant correlations between mandibular transverse dimension and total airway volume, sagittal, and vertical dimensions of the mandible. There may also be transverse differences between symptomatic and asymptomatic patients for sleep disorders in the pediatric population.

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