Over the last few years, there has been an increase in the clinical methods targeting the human tracheobronchial tree, both for therapeutic and diagnostic purposes. For these methods to be effective, a good understanding of the lung structure is necessary. This knowledge can be attained through the use of medical imaging protocols such as CT and MRI, and can in turn be used to predict aerosol deposition for particles employed for inhalation therapy via the simultaneous use of radionuclide imaging. However, due to limitations imposed by the technologies currently available, not enough information can be gathered in-vivo about the respiratory tract. Consequently, widespread use of anatomical models of the lung is being made by clinicians in order to enable them to fill this gap in information. The thesis is concerned with the improvement of such models and the introduction of new, more advanced ones in an effort to accurately describe the human lung using mathematical and physical principles. A method is developed for improving the Conceptual Model constructed in the Nuclear Medicine Department of Southampton General Hospital by incorporating to it real, patient-specific data obtained through CT imaging. A model of the bronchopulmonary segments of the lung is also created and an atlas that can be used for the identification of these sub-structures in any lung space is formed. An algorithm for the generation of a fully-descriptive 3D model of the airway tree is then designed and implemented, the morphometry of which is assessed to confirm that it is a realistic representation of the target organ. The deterministic algorithm reveals the 3D geometry and orientation of the lung airways, thus enabling aerosol deposition and flow-pattern studies to be performed in a comprehensive way in previously inaccessible regions of the lung.

No description available.

This thesis consists of an investigation of the current use of visual representations, and drawing in particular, when teaching and assessing within anatomy education in medical studies. Although we know a lot about teachers’ use of visual representations and increasingly drawing, especially in the context of science education, less is known about the use of those tools by educators in the anatomical domain. Drawing is not currently systematically being used within assessment in anatomy education in UK medical schools, and its potential in assessment has not been investigated in depth. Four studies were conducted to answer the research questions set for this thesis. The first study investigated the way in which the teaching staff understand the use of visual representations in teaching, learning and assessment in anatomy. To answer this, observations of seven anatomy demonstrators were conducted within Year 1 dissection sessions, and interviews were conducted with the same demonstrators. The second study employed a real-world experimental design to explore if students’ drawings reveal changes in their understanding after dissection. Drawings from 98 Year 1 medical students were analysed in a within-subject crossover design, where students in the first condition drew the exterior of the heart before dissection in Week 1 and drew the superior mediastinum after dissection in Week 2. The order was reversed for students in the second condition. All drawings were analysed for their content and form with an extensive coding scheme that was developed for this thesis, as the existing coding approaches towards drawings were judged as inappropriate. The third study investigated the use of drawing to reveal changes in understanding as the medical degree progresses. Drawings of the exterior of the heart from 46 Year 3 students were analysed and compared to drawings from the Year 1 students. Finally, the fourth study investigated the way in which anatomy demonstrators understand drawing in the assessment of anatomical knowledge; eight artefact-based interviews were conducted with anatomy demonstrators. The findings offer important insights into the way in which visual representations and drawing in particular are being used by anatomy demonstrators within anatomy education and their perspectives on the use of drawing in teaching, learning and assessment. A significant contribution is also made to the knowledge regarding the use of drawing to assess understanding in spatially intensive domains, such as the anatomical one. This thesis also contributes to our knowledge of dissection as a method of teaching anatomy and the need for drawing training within this domain. Finally, the scheme for drawing analysis that was developed, evaluated and employed in this thesis can be considered a methodological contribution to the approaches of analysing drawings in the current literature.

Monitoring blood perfusion and oxygenation changes is of vital importance and for this reason many different techniques have been developed over the decades. Photoplethysmography (PPG) is an optical technique that measures blood volume variations in vascular tissue and it is well known for its utilisation in pulse oximetry for the estimation of arterial blood oxygen saturation (SpO2). In pulse oximetry, mainly the pulsatile component of the signal (AC PPG) is used while the continuous DC component is mostly excluded. Near Infrared Spectroscopy (NIRS) is another optical technique that measures changes in the concentration of oxygenated (ΔHbO2), deoxygenated (ΔHHb), and total haemoglobin (ΔtHb) from the variations in light attenuations at different wavelengths. The main motivation of this research is to explore the capability of Photoplethysmography in assessing tissue perfusion and oxygenation similarly as NIRS. The hypothesis underlining this research is that the DC component of the PPG signal contains information on the overall absorbed light and this part of the PPG signal, acquired at least two wavelengths, may be used to obtain ΔHbO2, ΔHHb, and ΔtHb as performed in NIRS. Therefore, DC PPG attenuations may be related to haemoglobin concentrations by the modified Beer-Lambert law (MBLL). In order to investigate this, novel reflectance, custom-made PPG sensors and measurement systems, including advanced signal processing algorithms, have been developed for the acquisition and analysis of raw PPG signals (AC + DC) from different anatomical locations. Three in vivo studies on healthy volunteers were carried out in order to investigate if ΔHbO2, ΔHHb, and ΔtHb estimated from PPG could indicate changes in blood perfusion and oxygenation. The studies consisted of vascular occlusions on the forearm, negative bed tilting, and whole body cold exposure. Raw PPG signals were acquired from different locations such as the forearm, fingers, and forehead, whereas simultaneous NIRS signals were used as a reference. The results showed that ΔHbO2, ΔHHb, and ΔtHb could be effectively estimated from PPG signals. These parameters indicated the changes in blood volumes and/or oxygenation, whereas comparison with NIRS signals showed good levels of correlation and trending. These promising results showed that DC PPG signals could be used to monitor changes in blood perfusion and oxygenation, extending the range of applications of Photoplethysmography.

The differentiation of human endometrial stromal cells (HESCs) into specialised decidual cells prepares the endometrium for embryonic implantation. The biochemical and morphological transformation of these cells is highly temporally regulated in order to define a transient period of endometrial receptivity. Currently, the involvement of circadian machinery, and clock dependent pathways in this process are not fully understood. Firstly, analysis of circadian rhythms in HESCs revealed a consistent loss of oscillations in clock components upon decidualization. Down-regulation of Period 2 (PER2) expression, apparent in the early stages of differentiation, was shown to be sufficient to cause this aperiodicity. In turn, temporal suppression of PER2 expression was achieved via reduced CLOCK binding to a non-canonical Ebox enhancer in the PER2 promoter. RNA sequencing analysis upon premature PER2 knockdown revealed a disorganised decidual phenotype in which cell cycle and mitotic regulators were perturbed. As such, PER2 acts to uncouple the endometrium from circadian oscillations during decidualization. Secondly, the gene PRIP-1 was shown to be PER2 dependent in undifferentiated HESCs. Endometrial expression of PRIP-1 was induced and maintained upon decidualization by the post-ovulatory rise in progesterone. Analysis of Ca2+ fluxes demonstrated the ability of PRIP-1 to act as a chelator of IP3 signalling. Additionally, PRIP-1, via its regulation of the AKT pathway, is shown to be an anti-apoptotic regulator in decidual HESCs. Together, these results indicate PRIP-1 functions as a molecular switch in response to progesterone signalling. High PRIP-1 levels during differentiation enable AKT and IP3 mediated cell survival, whilst declining levels upon P4 withdrawal leads to decidual apoptosis. In summary, I provide a novel paradigm whereby both PER2 and PRIP-1 act to uncouple the endometrium from various signalling inputs, enabling an autonomous decidual response. Asynchrony in these pathways can lead to a cascade of events resulting in an array of adverse pregnancy complications.

Background: People with diabetes and peripheral neuropathy have been reported to show alterations in lower limb joint function compared to healthy non-diabetic people. Specifically the maximum angular movement available at certain joints can be reduced during static, non-weight bearing tasks. Limited joint range of motion has the potential to compromise balance and stability thereby increasing the risk of falling. It is unclear whether a reduction in the extent of movement available at the joints is reflected by a reduction in the amount of angular movement actually utilised during a functional task such as stair negotiation. The aim of this study was to determine if people with diabetes show reduced dynamic range of motion at the ankle, knee and hip joints during stair ascent and descent in comparison to controls. Falls risk during stair negotiation was calculated by measuring the degree of variability in dynamic joint range of motion. Methods: Data were generated from three groups: subjects with diabetes and peripheral neuropathy (DPN), diabetes without peripheral neuropathy (DM), and healthy controls (Ctl). The study was conducted in a gait laboratory using motion capture and related 3D software for analysis. Joint range of motion for the ankle, knee, and hip were captured during level walking, stair ascent, and descent. A seven step, bespoke staircase was fabricated for this purpose. Analysis of Variance (ANOVA) and Newman-Keuls tests were used to analyse the data. Results: Significantly reduced ankle range of motion, in the sagittal plane, was observed in the DPN group during stair ascent when compared to the controls. For stair descent, the DPN group demonstrated a significant increase in knee and hip ROM in the frontal plane, and also hip ROM in the transverse plane. No significant differences between the groups were identified for joint variability. Conclusions: People with DPN demonstrate alterations in dynamic range of motion at the lower limb joints during stair ascent and descent. The degree of angular movement utilised for both stair tasks was decreased at the ankle joint and this has the potential to undermine balance and stability. In contrast, angular movement at the knee and hip joints was increased in the frontal and transverse planes. This may compensate for impaired balance and stability by increasing the base of support to maintain balance and assist in foot clearance and placement. The specific combination of increased angular movement at the knee and hip may represent a compensatory stair gait strategy in response to reduced angular movement at the ankle joint.

Tendon injuries continue to be a financial burden on the health care system of many western countries, whilst also remaining common and a significant challenge within the orthopaedic discipline with no consensus of opinion on the best therapeutic regime to be employed. Many polymers have been investigated for use in tendon repair. A range of polymers have shown good integration with limited immune response. However, to date no implant has been capable of delivering the physical properties observed in native undamaged tendon. Many of the polymers implanted have resulted in re-rupture or reduced mechanical function. Therefore, improvements are required in the choice of polymer and mechanical properties of the polymer are required. One means of achieving such improvements is to utilise co-polymers such as PHBHHx, which have shown favourable elastic properties when the ratio of HHx to PHB has been increased. Therefore, a PHBHHx polymer based scaffold was investigated as a potential scaffold for tendon repair. Whilst, also investigating the potential of FGF-4, FGF-6 and FGF-8 to differentiate both human embryonic and mesenchymal stem cells towards a tenocyte-like lineage. Finally, an investigation into whether a controlled production of PHBHHx based nanoparticles could produce different nanoparticles sizes that can be predicted and result in differing release profiles. This may allow for the synthesis of size controlled nanoparticles capable of delivering differing drug concentrations and sustained release properties.

Injury to the bronchial epithelium in respiratory diseases such as asthma and COPD results in the loss of barrier function and an elevated sensitivity to environmental insults. An increased release of the endogenous cannabinoid, anandamide in response to inhalation of allergen in asthmatic patients has been reported. In contrast, previous clinical trial findings suggest anti-inflammatory and broncho-relaxant properties of the phytocannabinoid, ∆9-tetrahydrocannabinol (THC). The aim of this study was, therefore, to determine the effects of endocannabinoids and phytocannabinoids on bronchial epithelial cell permeability and to investigate the mechanisms involved. Calu-3 human bronchial epithelial cells were cultured at air-liquid interface to allow development of tight junctions. Changes in transepithelial electrical resistance (TEER), a reflection of epithelial permeability, were measured at various time points post-treatment. The endogenous cannabinoid anandamide produced a significant reduction in TEER, which was unaffected by cannabinoid receptor antagonists, but attenuated by URB597, an inhibitor of fatty acid amide hydrolase, and by a combination of cyclooxygenase and lipooxygenase blockade. Subsequent immunoblotting data revealed that the expression of tight junction proteins, occludin and ZO-1, were also reduced by anandamide. Inhibition of ERK activation by MEK1/2 inhibitors, PD98059 and U0126, prevented the anandamide-induced reduction in TEER and prevented the reduction in occludin expression. Thus, ERK activation is likely to mediate these effects by altering the expression of tight junction proteins. Treatment with THC prevented TNFα-induced decrease in TEER and increased in paracellular permeability. CB1 and CB2 receptor-like immunoreactivity was found in Calu-3 cells. Subsequent pharmacological blockade of either cannabinoid receptor inhibited the THC effect. In comparison, stimulation of both or either CB1 or CB2 receptors displayed similar effect to that of THC. Western immunoblotting also revealed reproducible decreases in occludin and ZO-1 expression in TNFα-treated cells, whereas cells pre-incubated with THC alone or in combination with TNFα did not alter expression levels. Phosphorylation of myosin-phosphatase target protein at threonine 696 residue by TNFα was attenuated in the presence of THC, indicating the involvement of RhoA/ROCK cascade. Selective stimulation of either cannabinoid receptor in TNFα-treated cells suggests THC-induced inhibitory effect on RhoA/ROCK signalling was mediated through CB2 receptor, and not CB1. In summary, these data suggest that the reduction in transepithelial resistance by anandamide, indicative of increased epithelial permeability, is caused by its metabolites rather than anandamide itself. Inhibition of anandamide degradation might provide a novel approach to treat airway inflammation. Conversely, THC reverses the reduction in transepithelial resistance caused by TNFα, through an effect at CB1 and CB2 receptors. Hence, THC, or perhaps other cannabinoid receptor ligands may have potential therapeutic roles in inflammation-induced changes in airway epithelial cell permeability, such as asthma and COPD.

Modelling the human eye provides a great challenge in both the field of mathematical medicine and in engineering. Four different problems regarding flow and deformation in the eyeball are considered, showing how changes in both the fluid and solid mechanicsof the human eye contribute to the development of pathological states. Firstly,a mathematical model is presented for the flow of aqueous humour through the trabecular meshwork and into the Schlemm canal. This predicts the intraocular pressure and investigates how this influences primary open angle glaucoma. Secondly, paradigm problems concerning the development of rhegmatogeneous retinal detachment are presented. A two-dimensional model of pressure driven fluid flow between rigid walls, and between one rigid and one moving wall is presented and followed by a three-dimensional model concerning liquefied vitreous humour flow induced by saccadic eye motion. The purpose of these models is to examine the flow behaviour and the deformation of the detached retina. Thirdly, a mathematical model of aqueous humour flow, driven by buoyancy effects through the detached descemet membrane in the anterior chamber, has been developed to analyse the fluid mechanics concerning the progression of descemet membrane detachment. Lastly, mathematical models studying the effects of a tonometer and a scleral buckle on the shape of the eyeball membrane are presented. The modelling of fluid flow in these studies is based on the lubrication theory limit of the Navier-Stokes equations. However, the full Navier-Stokes equations have been used in the development of a three-dimensional model of retinal detachment. In the modelling of the tonometry and scleral buckling the membrane theory of spherical shells has been used. The results of these models predict changes in the intraocular pressure as well as examining the fluid flow behaviour and the deformation of the detached retina. The modelling of descemet membrane detachment is shown to explain the progress of the spontaneous reattachment and redetachment of descemet membrane may be controlled under the correct conditions. The results of the modelling of the tonometer cast doubt on the Imbert-Fick law, but the results of the scleral buckle may prove useful to predict changes in the focal length of the eye when a scleral buckle is present.

The ability to quantify kinematic parameters of the knee is crucial in understanding normal biomechanics, recognising the presence of pathology and its severity, planning treatment and evaluation of outcomes. Current methods of quantifying lower limb kinematics remain limited in allowing accurate dynamic assessment. Computer assisted surgery systems have been validated in quantifying kinematic parameters, but remain limited to the operative setting. Recently, image-free computer assisted surgery technology has been adapted for non-invasive use and validated in terms of repeatability in measuring coronal and sagittal femorotibial mechanical alignment in extension. The aim of this thesis was to develop and implement a set of validation protocols to quantify the reliability, precision and accuracy of this non-invasive technology in quantifying lower limb coronal and sagittal femorotibial mechanical alignment, anteroposterior and rotatory laxity of the knee by comparison with a validated, commercially available image-free computer assisted surgery system. Pilot study confirmed feasibility of further experimental work and revealed that the noninvasive method measured with satisfactory precision and accuracy: coronal mechanical femorotibial alignment (MFTA) from extension to 30° knee flexion, anteroposterior translation in extension and tibial rotatory laxity during flexion. Further experiments using 12 fresh cadaveric limbs revealed that the non-invasive method gave satisfactory precision and agreement with the invasive system measuring MFTA without stress from extension to 40° knee flexion, and with 15Nm coronal stress from extension to 30° knee flexion. Using 100N of anterior force on the tibia, the non-invasive system was acceptably precise and accurate in measuring sagittal tibial displacement from extension to 40° flexion. End of range apprehension, such as has been proven repeatable in measuring tibial rotatory laxity was used and the non-invasive method gave superior 3 precision and accuracy to most reported non-invasive devices in quantifying tibial rotatory range of motion. Non-invasive optical tracking systems provide a means to quantify important kinematic parameters in health and disease, and could allow standardisation of knee examination increasing communicability and translation of findings from the out-patient to operative setting. This technology therefore could allow restoration of individual specific kinematics in knee arthroplasty and soft-tissue reconstruction.