Heterogeneity of type-II interleukin-1 receptors. Heterogeneity of B-cell interleukin-1 binding created by dimerization of type-II interleukin-1 receptors.

The binding of IL-1 alpha and IL-1 beta to two human lymphoblastoid B-cell lines, Raji and RPMI 1788, was compared with binding to the murine T-cell line, EL4. Dramatic differences in IL-1 binding were observed. Both human B-cell lines bound much less IL-1 alpha than IL-1 beta, expressed 5-10 times more receptors per cell for IL-1 beta than did the EL4 cell line, and demonstrated a large difference in the ability of IL-1 alpha to compete with IL-1 beta for binding. The B-cell lines demonstrated a low number of high-affinity IL-1 alpha receptors and a large number of IL-1 alpha receptors with a much lower affinity. Inhibition studies demonstrated that only IL-1 beta could compete for the binding of radiolabeled IL-1 beta to the B-cell IL-1R. Furthermore, SDS-PAGE analyses of lysates of the B-cell lines that had been affinity cross-linked with 125I-IL-1 alpha revealed two bands corresponding to IL-1R structures of 60 and 110 kD. These results coupled with a nonequilibrium binding study suggested a dimerization of a common type-II IL-1R polypeptide, the dimer being responsible for the high-affinity IL-1 alpha-binding site of the B-cell lines.

Apparent age-related bone loss among adult female Gombe chimpanzees.

Apparent age-related bone loss among adult females was observed in a skeletal sample derived from the free-ranging Gombe chimpanzee population of Tanzania. Photon absorptiometric and computed tomographic bone scans indicated that, as in humans, bone was lost from the endosteal surface, but, in contrast to humans, more bone was lost from cortical sites than from cancellous sites. The etiology of this bone loss may be related to a number of factors, including hormonal changes, nutritional inadequacy, and decreased physical activity late in life coupled with the demands of pregnancy and lactation.

Computed tomographic measurement of cortical bone geometry.

In this study digital images of bone cross-sections obtained by computed tomography were analyzed with an automated outlining method. It was shown that unbiased cross-sectional geometric measurements of cortical bone could be obtained if the periosteal and endosteal surfaces were defined at separate thresholds. Use of different threshold levels for these two surfaces resulted in errors of 2.6% for periosteal diameters, 7.4% for endosteal diameters and 7.3% for cortical area. If incorrect thresholds were used, cortical thickness measurements can have errors as high as 30%. In addition, simulated variation in medullary fat content did not affect measurement of medullary dimensions.

Dual energy computerized tomography: a simplified approach.

Attenuation numbers of various organic liquids were measured in a phantom at the low and high X-ray beam settings of the Mark I and CT 1010. The readings were translated into absolute units and ratios computed. There is a nonlinear relationship between this ratio and the effective atomic number of the compounds tested. A ratio of one defines a substance with energy dependence like water. Ratios below one definite anhydrous substances composed of elements with low atomic numbers. Ratios greater than one defined substances containing elements with high atomic numbers.

A correlative study of computed tomography and histology in human and experimental vasogenic cerebral edema.

The computed tomography (CT) scans of nine patients with vasogenic cerebral edema and five monkeys with cryogenic lesions were correlated with histologic findings. The areas of diminished density on the CT scan corresponded to foci of histologically recognizable edema. The attenuation number of the edematous tissue in the human varied from 18.0 to 28.8 Hounsfield units (HU: 1,000 scale) and in the monkey from 27.0 to 34.7 HU. There was a rough correlation between the extent of decrease in the attenuation number and the degree of staining of edematous tissue by the periodic acid-Schiff method. The decreased attenuation number of edematous tissue signifies dilution by edema fluid only when it is above 20 HU or represents a change of less than 12 HU. Lower numbers imply an additional process, possibly transformation of complex into neutral lipids. It is our belief that cerebral edema in the human can be quantitatively studied with the presently available CT scanners.