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The thylakoids of Rhodopseudomonas viridis have been studied by freeze-fracturing whole cells. Depending on growth conditions and treatment before freezing, three different types of particle arrangements in the photosynthetic membrane are reported: a random arrangement, an isometric (quadratic) lattice arrangement with a lattice constant of 12.5 ± 0.8 nm, and a hexagonal lattice arrangement with a lattice constant of 12.5 ± 0.8 nm. [ABSTRACT FROM AUTHOR]

Bone density has been assessed during and after radiotherapy of metastases of the spine using quantitative computed tomography (QCT) in 19 patients with osteolytic vertebral lesions. All patients underwent external photon radiation with a total dose of 40 Gy over a period of 4 weeks. Measurements of vertebral mineral density were performed at the beginning, at the end, and 3 months after radiotherapy. In 13 patients with osteolytic metastases, radiotherapy achieved complete release of pain; it was unsuccessful in the remaining 6 patients. Immediately after successful radiotherapy, osteolytic metastases showed a decrease of bone density of 24.7% followed by an increase of 60.6% 3 months later. Normal bone surrounding the osteolysis showed an increase of density at the end and 3 months after radiotherapy. QCT has proved to be a helpful tool in assessing successful radiotherapy of metastases of the spine. [ABSTRACT FROM AUTHOR]

To estimate subchondral mineralisation patterns which represent the long-term loading history of individual joints, a method has been developed employing computed tomography (CT) which permits repeated examination of living joints. The method was tested on 5 knee, 3 sacroiliac, 3 ankle and 5 shoulder joints and then investigated with X-ray densitometry. A CT absorptiometric presentation and maps of the area distribution of the subchondral bone density areas were derived using an image analyser. Comparison of the results from both X-ray densitometry and CT-absorptiometry revealed almost identical pictures of distribution of the subchondral bone density. The method may be used to examine subchondral mineralisation as a measure of the mechanical adaptability of joints in the living subject. [ABSTRACT FROM AUTHOR]