Browsing by Author "Barr, H."

Now showing 1 - 6 of 6
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    Advancing the clinical application of Raman spectroscopic diagnosis of oesophageal pre-malignancies
    (Cranfield University, 2009-01) Hutchings, J.; Stone, Nicholas; Kendall, Catherine; Barr, H.
    Raman spectroscopy is a technique that utilises inelastic scattering processes to provide a biochemical fingerprint that has been shown to successfully discriminate oesophageal pathologies. The aim of this study was to develop Raman spectroscopy as a clinical tool; both in vivo for ‘targeted biopsy’, and in ex vivo for ‘automated histopathology’. Two different Raman probes were evaluated and compared and tissue classification models generated ex vivo. A preliminary classification model of a novel single collection fibre probe demonstrated potential for the probe design. Both probes were shown to discriminate three different oesophageal pathology groups. A cross-validated tissue classification model (88 samples) discriminated normal, Barrett’s and neoplasia with an overall accuracy of 86.5% with a sensitivity of 83.3-89.5% and specificity of 89.2-97.1%. A novel rapid Raman mapping technique was evaluated. It was shown that sufficient biochemical information for pathology diagnosis could be extracted from low signal to noise ratio data using multivariate analysis providing the dataset was sufficiently large, thus demonstrating the feasibility of automated histopathology in a clinically realistic time frame. Furthermore, it was demonstrated that high spatial resolution imaging was not necessarily required for automated histopathology using novel interpretation of multivariate techniques. A tissue classification model generated from two rapid Raman maps containing separated substrate, normal, HGD, luminescence and fibrous connective tissue with an overall training performance of 97.5% Problems limiting clinical implementation of Raman techniques were investigated and methods of overcoming devised.
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    The hydraulic lung
    (2004-10) Prime, David; Turner, Anthony P. F.; Barr, H.
    A Hydraulic Lung has been designed and constructed. The Hydraulic Lung can inhale through a Dry Powder Inhaler (DPI) with a pre-determined level of inspiratory effort, and the characteristics of the inhalation profile generated, such as the peak pressure drop, peak flow rate and the flow acceleration are determined by the resistivity of the inhaler. The Hydraulic Lung has been used to explore the relationship between the level of inspiratory effort, the DPI resistivity and the resultant profile characteristics. A simple empirical equation has been found to describe the peak pressure drop achieved for any given level of inspiratory effort and device resistivity. This equation can be adapted to provide the equivalent peak inspiratory flow rate. A second simple empirical equation was found to describe the flow acceleration rate achieved under defined conditions of inspiratory effort and device resistivity. A clinical study has been performed to generate equivalent human inhalation data. A comparison between the relationships derived from the Hydraulic Lung data and the human inhalation data has demonstrated the validity of the key equation for pressure drop as a tool for predicHng human inhalation characteristics. The equation for flow acceleration rate was found to underestimate the flow accelerations achieved by human volunteers, but with slight modification could be used for this purpose. Correlations were established between the findings from this study and the work of earlier researchers in this area, which was based on clinical data alone. The Hydraulic Lung was also used as a practical tool for the evaluation of DPI performance in-vitro, including the behaviour of devices with variable resistivity which cannot easily be assessed using either standard pumps or sophisticated apparatus such as the Electronic Lung.
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    The study of molecular markers for the progression of Barrett's Oesophagus to adenocarcinoma to identify markers that can be used as diagnostic tools.
    (Cranfield University, 2002-05) Cadd, Verity Anne; Warner, P.; Barr, H.; Shepherd, N. A.
    Barrett's oesophagus is a complication of gastro-oesophageal reflux disease and is the single most important predisposing factor for the development of adenocarcinoma of the oesophagus. New molecular markers are needed for early diagnosis and to monitor disease progression. Telomerase is a ribonuclear protein with reverse transcriptase activity, which uses its own RNA component as a template for the addition of telomeric repeats to the end of chromosomes. Telomerase activity has been studied during the neoplastic progression of Barrett's oesophagus using a TRAP based ELISA technique, which found telomerase to be reactivated early during . disease progression. A non-isotopic method of in situ hybridisation for the detection of the RNA component of telomerase has also been successfully developed. Plasminogen activation is an inducible extracellular proteolytic system involved in the regulation of cellular interactions and invasion. The components of the urokinase-type Plasminogen Activator system have been fully investigated during the progression of Barrett's oesophagus to adenocarcinoma utilising immunohistochemistry and ELISA techniques. Changes in the expression of this invasive phenotype were found to occur late during disease progression in malignant tissues. Two-oesophageal cell-lines have been characterised using molecular biological techniques to detect a range of molecular markers to produce ex vivo models of oesophageal adenocarcinoma and oesophageal squamous cell carcinoma. In order to assess the effects of bile salts and acidity on oesophageal tissues these celllines were then utilised as ex vivo models. Exposure to acidic conditions both alone and with bile salts altered the morphological appearance of the cells and disrupted adhesion molecules in the cellular membrane. Investigations into both telomerase reactivation and the plasminogen activator system have provided new information concerning the nature and timing of molecular changes during the Barrett's metaplasia/dysplasia/ adenocarcinoma sequence.
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    Study of Raman spectroscopy for the early detection and classification of malignancy in oesophageal tissue
    (Cranfield University, 2002-10) Kendall, Catherine; Greenhalgh, Douglas A.; Barr, H.; Stone, Nicholas
    Raman Spectroscopy for the identification and classification of malignancy in the oesophagus has been demonstrated in this thesis. The potential of Raman spectroscopy in this field is twofold; as a adjunct for the pathologist and as a biopsy targeting tool at endoscopy. This study has demonstrated the feasibility of these potential applications in vitro. Spectral diagnostic models have been developed by correlating spectral information with histopathology. This is the current 'gold standard' diagnostic method for the identification of dysplasia, the established risk factor for the development of oesophageal cancer. Histopathology is a subjective assessment and widely acknowledged to have limitations. A more rigorous gold standard was therefore developed, as part of this study, using the consensus opinion of three independent expert pathologists to train the diagnostic models. Raman spectra have been measured from oesophageal tissue covering the full spectrum of malignant disease in the oesophagus, using a near infrared Raman spectrometer customised for tissue spectral measurements. Two spectral datasets were measured with different volumes of tissue probed using twenty and eighty times magnification ultra long working distance objectives. Multivariate statistical analysis has been used to extract the required spectral information with the greatest discriminative power. Principal component fed linear discriminant spectral models have been tested with leave one out cross validation procedures. Three pathology group models have correctly classified up to 91% of spectra, and eight group models have correctly classified up to 82% of spectra. Optimisation of the spectral models by selection of significant principal components, filtering the data and using staggered models was investigated. Effort has been made to understand the findings in their clinical context, with review of patient history and clinical progress, long term follow up is required. Preliminary work projecting independent data on to the models has been encouraging with 76% of the spectra in the three group model correctly classified, approaching classification levels of the training dataset. Formalin fixed tissue models were demonstrated to perform well, with 80% of the spectra were correctly classified in the seven group model. This further demonstrates the potential of Raman spectroscopy as a pathology tool. If Raman spectroscopy is to be implemented in a clinical setting it must be transferable between different measurement systems. This has been evaluated with oesophageal tissue spectra measured on two systems using three objectives. Simple calibration has demonstrated the use of multiple systems and measurement parameters in the development and application of spectral classification models. Testing of a new design of fibre probe has provided encouraging preliminary results. There is potential for the application of Raman spectroscopy in vivo, however the technology remains immature. Spectral maps of samples taken from across the spectrum of disease have shown clear delineation of the morphological features seen on the H&E images. Furthermore the biochemical information elicited has been analysed. Initial measurements of oesophageal tissue using multiphoton imaging have demonstrated the potential of collagen autofuorescence in the diagnosis of malignant change.
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    Towards objective endoscopic diagnosis of Barrett's associated early neoplasia using fibre-optic Raman Spectroscopy
    (Cranfield University, 2012-08) Almond, Laurence Maximilian; Kendall, Catherine; Hutchings, J.; Morgan, Sarah; Barr, H.
    This translational research evaluates a novel, custom-built Raman probe for potential application as an in vivo diagnostic tool in the oesophagus. Raman spectroscopy (RS) is a well established analytical technique which is capable of probing the biochemical changes associated with neoplastic progression in oesophageal tissue. RS relies on measurement of subtle inelastic scattering signals following monochromatic laser excitation. Clinical utilisation of RS within hollow organs requires accurate collection and transmission of signal through fibre-optic cables. This research aims to evaluate the ability of a custom built fibre-optic Raman probe, in conjunction with multivariate classification models, to differentiate between benign and neoplastic oesophageal pathologies ex vivo. The need for spectral stability and reproducibility are addressed, as are difficulties associated with multisystem reliability. In addition, the biochemical basis of spectral classification is evaluated and discussed. Cont/d.
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    Volatile diagnostic techniques for ventilator associated pneumonia
    (Cranfield University, 2010-02) Humphreys, Martyn Lee; Kendall, Catherine; Magan, Naresh; Barr, H.
    Ventilator associated pneumonia (VAP) is a significant challenge for the Intensive Care doctors worldwide. It is both difficult to diagnose accurately and quickly and to treat effectively once the diagnosis has been established. Current diagnostic microbiological methods of diagnosis can take up to 48 hours to yield results. Early diagnosis and treatment remain the best way of improving outcome for patients with VAP. In this study we look at novel diagnostic techniques for VAP. Electronic nose (Enose) technology was used to identify to identify the presence of microorganisms in bronchoalveolar lavage (BAL) fluid samples taken from the respiratory tracts of ventilated patients. The results were compared with standard microbiological culture and sensitivities. The Enose was able to discriminate 83% of samples into growth or no growth groups on samples grown in the lab. When the technique was employed to samples taken directly from patients the accuracy fell to 68.2%. This suggests that patient related factors may be reducing the accuracy of the Enose classification. The use of antimicrobial drugs prior to patient sampling is likely to have played a major role. The second part of this study used Gas Chromatography-Mass Spectrometry (GC-MS) analysis of patient’s breath in an attempt to identify patients with VAP. Breath samples were taken at the same time as the bronchoalveolar lavage samples described above. The use of this technique did show differences between the breath samples of patients who did not have any microbiological growth from their BAL samples and those that did. Leave one out cross validation of a PC fed LDA model showed 84% correct classification between healthy volunteers, no growth and growth groups. Finally, we evaluated the Breathotron, which is a breath analysis device designed and built at Cranfield Health. It allows for analysis of breath samples using a single sensor system as opposed to a sensor array employed in traditional Enose devices. This allows it to be more portable and cheaper to build. The Breathotron also allows collection of breath onto sorbent cartridges for GC-MS analysis. Its single sensor did not allow for accurate discrimination between samples.