Interleukin 1 and tumour necrosis factor increase phosphorylation of fibroblast proteins

AbstractInterleukin 1 (IL1) or tumour necrosis factor (TNF) stimulated phosphorylation of a triad of 27 kDa phosphoproteins (pI 6.0, 5.7 and 5.5) in human dermal fibroblasts. The change was dependent on the dose of cytokine in the range 0.1–20 ng, was detectable between 3 and 5 min after stimulation and was maximal by 10 min. The proteins were found in the cytosol after subcellular fractionation. The 32P was removed from them by alkali, indicating the presence of phosphoserine and/or phosphothreonine. The results suggest that early changes in serine/threonine protein kinase activity may be involved in responses of fibroblasts to IL1 and TNF

OSTEOBLASTS MEDIATE INTERLEUKIN-1 STIMULATION OF BONE-RESORPTION BY RAT OSTEOCLASTS

A monocyte-derived factor with IL-1-like properties has recently been shown to cause resorption of bone in organ culture. We have investigated the action of IL-1 on disaggregated populations of osteoclasts, incubated alone or in the presence of osteoblastic cells, in an attempt to identify the target cell for IL-1 in bone, and to elucidate the mechanism by which IL-1 induces osteoclastic resorption. Osteoclasts were disaggregated from neonatal rat long bones and incubated on slices of human femoral cortical bone. Under these conditions, the majority of osteoclasts form distinctive excavations in the bone surface within 24 h, the volume of which can be quantified by computer-assisted morphometric and stereophotogrammetic techniques. IL- 1 had no effect on bone resorption by osteoclasts alone, but when incubated in the presence of calvarial cells or cloned osteosarcoma cells, it induced a 3.8 (+/- 0.38)-fold increase in osteoclastic bone resorption, with significant enhancement at concentrations of greater than or equal to 30 pg/ml. The osteoblastic populations themselves did not resorb bone. The mechanism by which osteoblastic cells stimulate osteoclasts did not appear to depend upon PG synthesis; nor could we detect a diffusible substance in the medium of stimulated cocultures. These results indicate that IL-1 stimulates bone resorption through a primary action on osteoblasts, which are induced by IL-1 to transmit a short-range signal that stimulates osteoclastic bone resorption

Selective activation of JNK/SAPK by interleukin-1 in rabbit liver is mediated by MKK7

AbstractActivation of jun N-terminal kinase (JNK)/stress-activated protein kinase (SAPK) by interleukin-1 (IL-1) has been reported in many cells and in rabbit liver. Here we report selective activation of JNK/SAPK, without activation of p38 or p42 mitogen-activated protein kinases (MAPKs), by IL-1 in rabbit liver. We identified an IL-1 regulated JNK/SAPK activator present in rabbit liver using S Sepharose chromatography. It was purified and immunoprecipitated by two antisera to MAP kinase kinase 7 (MKK7). It was not recognised by an antibody to MKK4. We conclude that MKK7 is the activator of JNK/SAPK activated by IL-1 in liver and that JNK/SAPK is the only MAPK activated by IL-1 in liver

Diffraction Considerations for Planar Detectors in the Few-Mode Limit

Filled arrays of bolometers are currently being employed for use in astronomy from the far-infrared through millimeter parts of the electromagnetic spectrum. Because of the large range of wavelengths for which such detectors are applicable, the number of modes supported by a pixel will vary according to the specific application of a given available technology. We study the dependence of image fidelity and induced polarization on the size of the pixel by employing a formalism in which diffraction due to the pixel boundary is treated by propagating the second-order statistical correlations of the radiation field through a model optical system. We construct polarized beam pattern images of square pixels for various ratios of p/\lambda where p is the pixel size and \lambda is the wavelength of the radiation under consideration. For the limit in which few modes are supported by the pixel (p/\lambda<1), we find that the diffraction due to the pixel edges is non-negligible and hence must be considered along with the telescope diffraction pattern in modeling the ultimate spatial resolution of an imaging system. For the case in which the pixel is over-moded (p/\lambda>1), the geometric limit is approached as expected. This technique gives a quantitative approach to optimize the imaging properties of arrays of planar detectors in the few-mode limit.Comment: 20 pages, 8 figure