Areas Of High Uptake Research Articles

An experimental model to study the relationship between blood flow and uptake for bone-seeking radionuclides in normal bone

An experimental model has been developed in which the blood flow into the nutrient artery of a canine tibia is controlled by a Harvard infusion pump. This model has been used to study the extraction of the bone-seeking radionuclide technetium-99m labelled methylene diphosphonate at two flows through the tibia. The results of these experiments form the basis of a discussion concerning the relative importance of blood flow in determining the uptake of bone-seeking radionuclides. Although areas of increased radionuclide uptake observed in bone scans are associated with increased blood flow to that area, the results indicate that, in normal bone, the rate at which the nuclides are taken up is not limited by the blood flow. The authors conclude that other factors, in addition to blood flow, must be involved in producing areas of high radionuclide uptake in bone.

Stereotactic biopsies and computer tomography in gliomas

This study was carried out in order to obtain data on the relation between tumour structures seen in computer tomograms and the corresponding histopathology and cytology. Nine consecutive patients were studied, and stereotactic biopsies were obtained from sites determined on contrast enhanced computer tomograms. Biopsies were obtained from tumour areas with high and low contrast uptake and from the low attenuating areas surrounding the tumours. The results indicated a close correlation between the microscopical morphology of gliomas and the pattern of the computer tomogram. Biopsy samples from low-uptake central areas contained tumour tissues, necrotic tissue, and in one case a cyst. Biopsies from high-uptake areas typically contained tumour tissue, whereas biopsies from low-uptake surrounding areas contained oedematous non-tumour tissue. For tumour diagnosis biopsies should be obtained from both low and high attenuating tumour areas.

Time dependence of [ 131I]albumin uptake following removal of an experimental aortic stenosis

The uptake of trypan blue and [ 131I]human serum albumin (HSA) has been studied in the dog's abdominal aorta between 1 and 42 days after removal of an experimental stenosis (∼90%) applied 1 week previously. Previous work has shown that when the stenosis was present during circulation of these markers, their uptake was increased immediately proximal to the stenosis decreasing to normal by the renal artery level. Distal to the stenosis uptake was reduced apart from small areas of high uptake probably due to turbulent jet impacts. Within the stenosed section the uptake was normal. In this present study it was found that, after removal of the stenosis, proximal uptake initially remained elevated, returning to normal after ∼15 days whilst the distal uptake returned to normal after ∼ 10 days. In the previously stenosed section uptake was increased markedly following the release of the stenosis but returned to normal within ∼20 days. The relationship of these findings to alterations in the local haemodynamic state and to possible changes in endothelial morphology are discussed.

Influence of experimental stenosis on uptake of albumin by the abdominal aorta

The influence of abdominal aortic stenosis on the uptake of the protein-binding trypan blue dye and 131I human serum albumin (HSA) has been studied. The major change was a region of high uptake proximal to the stenosis, returning to normal by the level of the renal arteries. There was reduced uptake distal to the stenosis, apart from occasional small areas of high uptake probably due to turbulence. The increase in uptake immediately proximal to the stenosis was dependent on the severity and duration of the stenosis. Removal of the stenosis immediately before the injection of dye and 131I-HSA still resulted in elevated uptake in the proximal region. Some haemodynamic modifications resulting from a stenosis are described. It is suggested that the most satisfactory haemodynamic explanation of the observed uptake change is a proximal increase in oscillatory pressure/strain. The relevance of these findings to atherosclerotic development at and above arterial junctions is discussed.

Focal [3h]cholesterol uptake in the pig aorta Part 2. Distribution of [3h]cholesterol across the aortic wall in areas of high and low uptake in vivo

Focal areas of increased uptake of [3H]cholesterol in vivo by the macroscopically normal young pig aorta have been identified by their ability to accumulate the protein-binding azo dye, Evans blue. The distribution of labelled cholesterol across the aortic wall in areas of dye uptake (blue areas) and no dye uptake (white areas) was determined at intervals from 10 min to 24 h after the injection of label. Labelled free cholesterol represented most of the label in the aorta. It was distributed non-uniformly across the aortic wall, with most label concentrated in the intima and inner media. Labelled cholesterol ester represented only a small proportion of the aortic label and was distributed evenly through the vessel wall. Free cholesterol activity and free cholesterol specific activity were greater in blue areas than in white areas. These differences were confined to the intima and inner media and also the adventitia. Free cholesterol distribution and DNA content and distribution across the aortic wall were similar in blue and white areas. It is suggested that the increased focal uptake of labelled free cholesterol by blue areas reflects a higher free cholesterol turnover in these areas, and that labelled plasma cholesterol enters the pig aorta mainly through the intima in vivo.

Focal uptake and gradient distribution of 3H-cholesterol in the pig aorta

Focal patterns of ³H-cholesterol uptake were demonstrated in the macroscopically normal 'lesion free' young pig aorta with the aid of the protein-binding azo dye Evans blue. The transmural distribution of labelled cholesterol in areas of both high and low aortic ³H-cholesterol uptake were studied at intervals from 10 min. to 24 hr. after the intravenous injection of 1.5 mCi of ³H-cholesterol. Cholesterol gradients were determined using serial 100 μ frozen sections from the endothelial surface to the adventitia, and the results expressed as the dpm 100 mg. dry weight, or dpm mg. DNA. ³H-Cholesterol entered the aorta rapidly and by 10 min. there was an appreciable distribution throughout the intima, media and adventitia. By 24 hr. most cholesterol activity was concentrated in the intima and inner media. In areas of both high and low cholesterol uptake, cholesterol activity in the media increased with time after the injection of label. In areas of high cholesterol uptake, identified by the intimal accumulation of Evans blue, the ³H-cholesterol activity within the intimal 200 μ was greater than in areas of low uptake. At 24 hr., the label was predominantly associated with unesterilied cholesterol, which showed a distribution gradient similar to that of total cholesterol. Esterified cholesterol activity was minimal, and distributed evenly throughout thc aortic wall. Both free cholesterol activity and free cholesterol specific activity were greater in blue than in white areas, and these differences persisted through most of the aortic wall. Free cholesterol and DNA content and distribution across the vessel wall were similar in blue and white areas. The results suggested that the increased uprake of labelled cholesterol by blue areas reflects a higher free cholesterol turnover in these areas, and that the intima is the principal point of entry of the labelled plasma cholesterol <i>in vivo</i>. This model can be used in the study of the very early structural and metabolic changes in atherogenesis.