Technical and statistical improvements for flow cytometric DNA analysis of paraffin-embedded tissue

Flow cytometric DNA analysis of paraffin-embedded solid tumors has permitted review of large series of archival tissue in attempts to relate abnormal DNA content to prognosis. Limitations of the technique include: 1) a laborious, time-consuming procedure; 2) variation in technique between laboratories; and 3) lack of an objective method of computing DNA indices. Critical evaluation of our technique has shortened the time involved in dewaxing and rehydration, selectively utilized patient's own normal tissue as the internal standard, proved reproducibility of stored specimens, standardized DNA index computation, and developed a statistical analysis to confirm aneuploidy. These technical improvements and the development of a statistical analysis provide a way to shorten the procedure time and standardize the data generated from flow cytometric DNA analysis so as to improve the quality of retrospective reviews of paraffin-embedded tumors and accelerate the definition of flow cytometry's role as a prognostic indicator.     

Protein folds, functions and evolution.

The evolution of proteins and their functions is reviewed from a structural perspective in the light of the current database. Protein domain families segregate unequally between the three major classes, the 32 different architectures and almost 700 folds observed to date. We find that the number of new topologies is still increasing, although 25 new structures are now determined for each new topology. The corresponding analysis and classification of function is only just beginning, fuelled by the genome data. The structural data revealed unexpected conservations and divergence of function both within and between families. The next five years will see the compilation of a definitive dictionary of protein families and their related functions, based on structural data which reveals relationships hidden at the sequence level. Such information will provide the foundation to build a better understanding of the molecular basis of biological complexity and hopefully to facilitate rational molecular design.     

THE GROWTH AND DURATION OF LIFE OF CELOSIA CRISTATA SEEDLINGS AT DIFFERENT TEMPERATURES

Daily measurements of hypocotyl length were made on Celosia cristata seedlings cultured in darkness under aseptic conditions at six constant temperatures between 14.5° and 40.5°C. At 40.5° roots did not penetrate the agar and only the hypocotyls that were supported by the wall of the test tube could be measured. The growth curves were of the generalized logistic type, but of different degrees of skewness. The degree of symmetry of the growth curves was influenced by temperature. At the lower temperatures the maximal growth rate came relatively late in the grand period of growth; at successively higher temperatures it came progressively earlier. The mean total time rate of growth (millimeter per diem) was found to be a parabolic function of the temperature. The maximum rate of growth was found from the curve to be at 30.48°C. The maximum observed rate of growth, and the maximum yield, were found to be at 30°C. At all temperatures above 14.5° the maximum growth activity fell in the second quarter of the whole growth period. At all temperatures tested other than 30°, and at all parts of the growth cycle, the growth yield as measured by height of hypocotyl at any given equivalent point was less than at 30°. The total duration of life of the seedlings, and the duration of life after the end of the growth period (intermediate period) were inversely proportional to the mean total growth rate. The observations on Celosia cristata seedlings are thus in accord with the "rate of living" theory of life duration. The optimal temperature for life duration is the minimum temperature, within the range of these observations.