Measurement of drug and macromolecule diffusion across atherosclerotic rabbit aorta ex vivo by attenuated total reflection–Fourier transform infrared imaging

2009 ◽  
Vol 14 (4) ◽  
pp. 044008 ◽  
Author(s):  
Francesca Palombo ◽  
Charlène B. Danoux ◽  
Peter D. Weinberg ◽  
Sergei G. Kazarian
Keyword(s):  
Fourier Transform ◽  
Infrared Imaging ◽  
Ex Vivo ◽  
Rabbit Aorta ◽  
Fourier Transform Infrared ◽  
Total Reflection ◽  
Attenuated Total Reflection ◽  
Fourier Transform Infrared Imaging

scholarly journals Application of Fourier transform infrared spectroscopic imaging to the study of effects of age and dietary l -arginine on aortic lesion composition in cholesterol-fed rabbits

2008 ◽  
Vol 6 (37) ◽  
pp. 669-680 ◽  
Author(s):  
Francesca Palombo ◽  
Stephanie G. Cremers ◽  
Peter D. Weinberg ◽  
Sergei G. Kazarian
Keyword(s):  
Fourier Transform ◽  
Structural Information ◽  
Ex Vivo ◽  
Density Ratio ◽  
Spectroscopic Imaging ◽  
Rabbit Aorta ◽  
Fourier Transform Infrared ◽  
Attenuated Total Reflection ◽  
Aortic Lesion ◽  
Atherosclerotic Lesions

Diet-induced atherosclerotic lesions in the descending thoracic segment of rabbit aorta were analysed ex vivo by micro-attenuated total reflection (ATR)–Fourier transform infrared (FTIR) spectroscopic imaging. The distribution and chemical character of lipid deposits within the arterial wall near intercostal branch ostia were assessed in histological sections from immature and mature rabbits fed cholesterol with or without l -arginine supplements. Previous studies have shown that both these properties change with age in cholesterol-fed rabbits, putatively owing to changes in the synthesis of nitric oxide (NO) from l -arginine. Immature animals developed lesions at the downstream margin of the branch ostium, whereas lipid deposition was observed at the lateral margins in mature animals. Dietary l -arginine supplements had beneficial effects in mature rabbit aorta, with overall disappearance of the plaques; on the other hand, they caused only a slight decrease of the lipid load in lesions at the downstream margin of the ostium in immature rabbits. ATR–FTIR imaging enabled differences in the lipid to protein density ratio of atherosclerotic lesions caused by age and diet to be visualized. Lipid deposits in immature rabbits showed higher relative absorbance values of their characteristic spectral bands compared with those in immature l -arginine-fed rabbits and mature rabbits. The multivariate methods of principal component analysis (PCA) and factor analysis (FA) were employed, and relevant chemical and structural information were obtained. Two distinct protein constituents of the intima–media layer at different locations of the wall were identified using the method of FA. This approach provides a valuable means of investigating the structure and chemistry of complex heterogeneous systems. It has potential for in vivo diagnosis of pathology.

Attenuated Total Reflection—Fourier Transform Infrared Imaging of Large Areas Using Inverted Prism Crystals and Combining Imaging and Mapping

2008 ◽  
Vol 62 (10) ◽  
pp. 1095-1101 ◽  
Author(s):  
K. L. Andrew Chan ◽  
Sergei G. Kazarian
Keyword(s):  
Fourier Transform ◽  
Spatial Resolution ◽  
Infrared Imaging ◽  
Fourier Transform Infrared ◽  
Total Reflection ◽  
Attenuated Total Reflection ◽  
Array Detector ◽  
Aqueous Environment ◽  
Depth Of Penetration ◽  
Ft Ir

Attenuated total reflection–Fourier transform infrared (ATR-FT-IR) imaging is a very useful tool for capturing chemical images of various materials due to the simple sample preparation and the ability to measure wet samples or samples in an aqueous environment. However, the size of the array detector used for image acquisition is often limited and there is usually a trade off between spatial resolution and the field of view (FOV). The combination of mapping and imaging can be used to acquire images with a larger FOV without sacrificing spatial resolution. Previous attempts have demonstrated this using an infrared microscope and a Germanium hemispherical ATR crystal to achieve images of up to 2.5 mm × 2.5 mm but with varying spatial resolution and depth of penetration across the imaged area. In this paper, we demonstrate a combination of mapping and imaging with a different approach using an external optics housing for large ATR accessories and inverted ATR prisms to achieve ATR-FT-IR images with a large FOV and reasonable spatial resolution. The results have shown that a FOV of 10 mm × 14 mm can be obtained with a spatial resolution of approximately 40–60 μm when using an accessory that gives no magnification. A FOV of 1.3 mm × 1.3 mm can be obtained with spatial resolution of approximately 15–20 μm when using a diamond ATR imaging accessory with 4× magnification. No significant change in image quality such as spatial resolution or depth of penetration has been observed across the whole FOV with this method and the measurement time was approximately 15 minutes for an image consisting of 16 image tiles.

scholarly journals Distinguishing active from quiescent disease in ANCA-associated vasculitis using attenuated total reflection Fourier-transform infrared spectroscopy

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Adam D. Morris ◽  
Camilo L. M. Morais ◽  
Kássio M. G. Lima ◽  
Daniel L. D. Freitas ◽  
Mark E. Brady ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Unmet Need ◽  
Fourier Transform Infrared ◽  
Total Reflection ◽  
Attenuated Total Reflection ◽  
Remission Induction ◽  
Disease Remission ◽  
Anca Associated Vasculitis ◽  
Active Disease ◽  
Quiescent Disease

AbstractThe current lack of a reliable biomarker of disease activity in anti-neutrophil cytoplasmic autoantibody (ANCA) associated vasculitis poses a significant clinical unmet need when determining relapsing or persisting disease. In this study, we demonstrate for the first time that attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy offers a novel and functional candidate biomarker, distinguishing active from quiescent disease with a high degree of accuracy. Paired blood and urine samples were collected within a single UK centre from patients with active disease, disease remission, disease controls and healthy controls. Three key biofluids were evaluated; plasma, serum and urine, with subsequent chemometric analysis and blind predictive model validation. Spectrochemical interrogation proved plasma to be the most conducive biofluid, with excellent separation between the two categories on PC2 direction (AUC 0.901) and 100% sensitivity (F-score 92.3%) for disease remission and 85.7% specificity (F-score 92.3%) for active disease on blind predictive modelling. This was independent of organ system involvement and current ANCA status, with similar findings observed on comparative analysis following successful remission-induction therapy (AUC > 0.9, 100% sensitivity for disease remission, F-score 75%). This promising technique is clinically translatable and warrants future larger study with longitudinal data, potentially aiding earlier intervention and individualisation of treatment.

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