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Biomedical subjects

P Sheldon

Publications and source records attributed to P Sheldon.

67 records · Page 4Linked to original sources
PubMed1983

Brain nuclear magnetic resonance imaging enhanced by a paramagnetic nitroxide contrast agent: preliminary report.

Contrast-enhancing agents for demonstrating abnormalities of the blood-brain barrier may extend the diagnostic utility of proton nuclear magnetic resonance (NMR) imaging. "TES," a nitroxide stable free radical derivative, was tested as a central nervous system contrast enhancer in dogs with experimentally induced unilateral cerebritis or radiation cerebral damage. After intravenous injection of TES, the normal brain showed no change in NMR appearance, but areas of disease demonstrated a dramatic increase (up to 45%) in spin-echo intensity and a decrease in T1 relaxation times. The areas of disease defined by TES enhancement were either not evident on the nonenhanced NMR images or were better defined after contrast administration. In-depth tests of toxicity, stability, and metabolism of this promising NMR contrast agent are now in progress.

Animals↗
PubMed1979

Metrizamide cisternography and computed tomography for the investigation of pituitary lesions.

Metrizamide cisternography and computed tomography (CT) have been performed on 22 patients suspected of having pituitary or suprasellar lesions, using a low dose of metrizamide. These patients would otherwise have been subjected to air encephalography. The technique is described and the results are presented. The lesions demonstrated included empty sellae and suprasellar extensions of pituitary tumours. We also identified those patients in whom there was no suprasellar extension of a pituitary tumour. The diagnostic information required was obtained in all cases by a combination of the two techniques and air encephalography was avoided in all but one case. The side effects were mild and no serious complications were encountered. We consider this combination of methods to be very useful for the investigation of pituitary lesions.

Humans↗
PubMed1975

Autoimmune New Zealand mouse. Alterations in C3 receptors, complement-induced clumps and follicular adherence of immune complexes.

Lymphocytes with free complement receptors are markedly diminished in autoimmune mice, probably as a reflection of a receptor blockage by immune complexes. There is also a slight decrease in Fc receptor-bearing cells and an increase in complement-induced clumps. These alterations may be related to a lack of immune complex fixation onto germinal centres and also may play a part in possible defects in T-B-cell co-operation, follicular localization of immune complexes and immune response control in autoimmune mice.

Animals↗
PubMed1974

Immunological studies in a case of T-cell leukaemia.

The blood lymphocytes from a case of prolymphocytic leukaemia were subjected to a battery of different tests in order to establish as certainly as possible their T or B cell type of origin. The results of the tests for surface markers indicated the T-cell origin of the leukaemic cells in this patient, and this provided a good opportunity to determine the participation of T cells in the various tests proposed for measuring human lymphocyte function.

Aminosalicylic Acids↗
PubMedDate not supplied

Temperature distribution measurements in two-dimensional NMR imaging.

This paper represents a preliminary study of the effects of regional temperature distribution in two-dimensional nuclear magnetic resonance (NMR) T1 imaging. It is found, as expected, that variations in local temperature appear as variations in the corresponding T1 image. The potential use of NMR T1 imaging in temperature measurements is evaluated in the case of water and blood samples. Using containers where the temperature could be either known or directly controlled with reasonable accuracy, images are obtained with samples having at least two regions at different temperatures. As expected, T1 is found to vary linearly with 1/T over the range of 0 degrees C to about 40 degrees C for blood. The potential use of T1 imaging in hyperthermia applications is also discussed.

Blood↗
PubMedDate not supplied

NMR imaging of experimental brain abscess: comparison with CT.

An experimental canine model of a brain abscess induced with alpha-streptococcus was imaged in the cerebritis and capsule stages by computed tomography (CT) with intravenous contrast enhancement and by nuclear magnetic resonance (NMR). An NMR imager equipped with a superconducting magnet operating at 3.5 kG was used for several imaging techniques. The NMR images were compared with the CT scans and with gross and microscopic neuropathologic findings. CT showed enhancement of the inflammatory focus at the site of capsule formation while the necrotic center retained its low-density appearance. Spin-echo NMR images demonstrated the presence and extent of abnormal infected brain tissue more accurately than contrast-enhanced CT. Spin-echo images showed the necrotic center, the surrounding inflammatory zone, and peripheral edema without discriminating distinctly between the latter two zones. Inversion-recovery NMR images depicted a lesion of lesser extent, showing the necrotic center circumscribed by the surrounding edematous brain tissue. The inversion-recovery technique was best for demonstrating gray- and white-matter contrast in normal brain and depicted edema as loss of contrast between the gray and white matter. NMR offers some advantages over CT in imaging brain abscess, and the variety of NMR imaging techniques is useful for characterizing the different pathologic areas.

Animals↗