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Biomedical subjects

J Mallard

Publications and source records attributed to J Mallard.

28 records · Page 2Linked to original sources
PubMed1978

The influence of size and radiopharmaceutical concentration ratio on the detection of abnormalities in clinical radionuclide imaging.

The effect of the size of an abnormality on its detectability was measured. The cylindrical abnormalities studied, with diameters ranging from 3 mm to 4 cm, were superimposed on a uniform background. To avoid artefacts produced by the imaging devices, the images were simulated by computer. The method of constant stimulus was used to determine the detectability of the abnormalities. By using a Perspex phantom filled with 99Tcm, measurements were made of the concentration ratio between abnormality and background which permitted detection of the abnormality. This allowed evaluation of the effectiveness of 99Tcm pertechnetate in the detection of small abnormalities. Assuming a concentration ratio between abnormal and normal tissue of 22.5:1, then at a depth of 50 mm in the brain a cylindrical abnormality of about 8 mm diameter was the smallest detectable under the chosen scanning conditions.

Brain Diseases↗
PubMed1976

The measurement of the performance of the display system of radioisotope imaging device: the multi-element band display.

An assessment has been made of the performance of the type of display system in which each display signal intensity, i.e. grey shade or colour, represents a range of count densities or counting rates. In the particular commercially available system used in this investigation eight different grey shades are used to display the image, a range of count densities beingallocated to each grey shade. It is shown experimentally that changes in the distribution of radioisotope can fail to be detected solely due to the manner in which the display is used, viz. The way in which the count density is allocated to the available grey shades. Also, it is shown experimentally that the best display performance can be achieved by using one in which the range of count densities represented by each grey shade is less than three standard deviations of the mean background [corrected] count density.

Background Radiation↗
PubMedDate not supplied

Isolation and long-term maintenance of differentiated adult chicken hepatocytes in primary culture.

Adult chicken hepatocytes were obtained by an adaptation of the two step in situ collagenase perfusion. Usually 0.5 to 1 x 10(9) cells were obtained, with 75 to 95% viability. Hepatocytes attached within 2 h when plated on plastic cell culture dishes and spread in 4 h, surviving for several months in a specific serum-free medium. These cells retained a typical parenchymal cell morphology and the ability to produce a specific protein (albumin) throughout the culture period. We hereby provide a suitable model for studying hepatic metabolism in birds.

Albumins↗