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T A Carpenter

Publications and source records attributed to T A Carpenter.

79 records · Page 5Linked to original sources
PubMed1991

Localized in vivo proton spectroscopy of the human kidney.

In vivo 1H spectroscopy using the STEAM sequence for localization has been applied to the human kidney in normal volunteers and subjects with successful renal transplants. We show that, within the resolution of our measurements, trimethylamines are present in the spectra from some of the subjects and absent from others. The prominent peak seen at 5.8 ppm in the spectrum is identified as that from urea and not lipid, as previously suggested.

Humans↗
PubMed1991

Cardiac tagging in the rat using a DANTE sequence.

We demonstrate the application of a DANTE tagging sequence to in vivo imaging of the rat heart. This sequence generates narrow parallel tag lines in a short space of time and is combined with cardiac gating to image the heart wall at eight points throughout the cycle.

Animals↗
PubMed1991

Magnetic resonance imaging in a model of atherosclerosis: use of a collar around the rabbit carotid artery.

Transverse cardiac-cycle gated high resolution magnetic resonance images have been obtained from the neck of the New Zealand white rabbit both in normal animals and from those in which a collar had been earlier positioned around one carotid artery. The study included animals fed on normal and on high cholesterol diets with the surgical modification having been demonstrated previously to cause a rapid and reproducible lesion resembling early atherosclerosis. The aim of the work was to investigate the attainable spatial resolution and sensitivity at a field strength of 2 T using a large radiofrequency transmitter system and a surface coil receiver with which spin-echo images have been obtained. Visualization was enhanced using a three-dimensional interpolation technique. An image resolution of 200 microns was readily obtained but was shown to be insufficient for delineating pathological features within the artery wall such as intimal layer thickening. The results have been compared with histopathological findings which confirmed that any morphological changes were within the pixel resolution of the image. Extensions to the methodology are proposed which should be able to detect atherosclerotic changes with a resolution of 50 microns within a feasible imaging time. In addition, the MRI study of how the surgical intervention alters the artery shape and curvature was carried out and the MRI demonstrated that collar implantation in general does not occlude the artery and causes only a slight and gradual degree of curvature to the vessel.

Animals↗
PubMed1990

Lipid characterization in an animal model of atherosclerosis using NMR spectroscopy and imaging.

High resolution 1H and 13C NMR spectroscopic measurements including 1H/13C 2D correlation and magnetic resonance imaging (MRI) studies, have been carried out on intact rabbit aortic tissues ex vivo using animals fed both normal and high cholesterol diets. The results show that 1H and 13C NMR spectroscopy can distinguish mobile lipids and can differentiate between normal triglyceride content and cholesterol-enriched lipids, in intact tissue, There were considerable differences in the level of deposition of cholesteryl esters in animals all fed on the same diet. Confirmation is presented of temperature-dependent differences in mobility and organization between the triglycerides found in control tissue and the cholesteryl esters found in aortas from high lipid diet animals. Water-suppressed MRI showed evidence of lipid accumulation in the aortas of high cholesterol diet rabbits. It is concluded that the hypercholesterolaemic rabbit model of atherosclerosis, coupled with such NMR methods, may offer a noninvasive method of monitoring disease development, allowing the evaluation of the effect of therapeutic agents on the progress of atherosclerosis.

Animals↗
PubMed1988

Magnetic resonance imaging of the delivery of a paramagnetic contrast agent by an osmotic pump.

The successful application of Magnetic Resonance Imaging (MRI) in verifying the in vitro delivery action of an osmotically-driven pump (Alzet 2ML1) is described. MRI detection of drugs commonly used with such pumps is not yet possible because of the low signal intensity of present MR techniques. So we employed a paramagnetic contrast agent (gadolinium diethylene triamine penta acetic acid) of molecular weight comparable to commonly used drugs, and solutions of comparable concentration and viscosity. The study highlights the potential of this approach in the evaluation of in vivo drug delivery systems.

Contrast Media↗
PubMed1986

Aluminosilicates and senile plaque formation in Alzheimer's disease.

Aluminium and silicon were found to be colocalised in the central region of senile plaque cores in studies with energy dispersive X-ray microanalysis. The distribution of these elements was similar in cores isolated from the cerebral cortex of patients with senile dementia of the Alzheimer type and in cores studied in situ from tissue sections from the cerebral cortex of presenile and senile patients with Alzheimer's disease, and elderly, mentally normal patients. High-resolution solid-state nuclear magnetic resonance techniques showed aluminium and silicon to be present as aluminosilicates. The presence of aluminosilicates at the centre of senile plaque cores contrasts with the distribution of other inorganic constituents and suggests that they may be involved in the initiation or early stages of senile plaque formation.

Aged↗