[The diagnostic value of conventional x-ray diagnosis and quantitative mineral measurements in patients with clinical symptoms of osteoporosis]. / Diagnostische Wertigkeit der konventionellen Röntgendiagnostik und der quantitativen Mineralometrie bei Patienten mit klinischer Osteoporosesymptomatik.

The problem of differentiating between patients suffering from osteoporosis and those with healthy bones is discussed on the basis of distribution of the age-specific and sex-specific mineral salt values in a healthy population and in a population with clinically manifest osteoporosis. By comparing the results of quantitative mineralometry and conventional x-ray films of the human skeleton in a histologically clarified group of persons with clinically manifest osteoporosis signs and symptoms, the diagnostic ranking of both methods is assessed and discussed.

Cell-cycle-related metabolic and enzymatic events in proliferating rat thymocytes.

Cell-cycle progression of rat thymocytes stimulated with concanavalin A and interleukin 2 was monitored at 12-h intervals by pulse labeling aliquots of the cell culture with [3H]thymidine, by measuring cellular DNA and protein content and by counting the number of cells in the cultures. The cell cycle was completed after 96 h of culture with the S phase peaking at 48 h. Early events in thymocyte activation were enhanced phosphatidylinositol turnover and the induction of ornithine decarboxylase. Concomitant changes were observed in the rates of DNA synthesis and glycolysis accompanied by a 20-fold increase in glucose uptake 48 h after stimulation. However, the maximal increment in the glycolytic rate preceded that of DNA synthesis by 12 h. Apart from the quantitative changes which occurred during the cell-cycle progression, there was also a change from partial aerobic glucose degradation to CO2 (26%) to almost complete anaerobic conversion of glucose to lactate (85%) and less than 3% to CO2. Glycolytic enzyme levels increased fourfold to tenfold and reached their maxima 48 h after mitogenic stimulation. Maximal increments of glycolytic enzyme activities preceded or coincided with the maximal increments of the glycolytic rate. Actinomycin D (1.5 ng/ml) completely inhibited DNA and RNA synthesis but did not show any inhibitory effect either on glycolytic enzyme induction or on enhanced glycolysis. During mitosis and return of the cells to the non-proliferative state, all of the enhanced metabolic rates returned to their initial levels and the elevated enzyme activities were decreased also. The marked changes of metabolic rates and enzyme activities observed at the various phases of the cell cycle suggest that these biochemical events may also serve as suitable parameters for evaluating the response of lymphocytes towards mitogens and lymphokines.