Transfusion of PCs in PAS-2 significantly reduces the incidence of reactions. The 1-hour and 20-hour CCIs after transfusion of PCs in PAS-2 were significantly lower than the CCIs after transfusion of PCs in plasma. Because storage conditions of both PCs were found to be optimal, the decrease in CCIs after transfusion of PCs prepared in PAS-2 may be caused by rapid elimination of a subpopulation of P-selectin-positive platelets from the circulation.

The combination of Mg(2+) and K(+) gave significantly (p < 0.05) lower platelet CD62 expression in the storage medium than in PAS-2. The effects of these differences on platelet metabolism and in vivo properties remain to be investigated.

The new oxygen-permeable containers showed platelet quality comparable to that with the PL-732 and for longer storage periods and at higher platelet counts.

During 7 days of storage in a new 1.3-liter platelet container, the pH was maintained above 6.8 in PCs in plasma with a yield between 1.5- and 4.5 x 10(11)/U; when PAS II was used, the maximum platelet yield allowed for comparable pH maintenance was somewhat lower (4.0 x 10(11)/U).

A microdensitometry method that allows estimation of the distribution of the DNA content of nuclei in thin tissue sections is described. The method is based on a theoretical model of Feulgen-stained spherical nuclei, of different sizes, in each of which the DNA is present as a homogeneous solution. In thin sections of nuclei of different sizes, the fraction of DNA per section is inversely proportional to the radius of the nucleus. Histograms of the product of DNA content andThe interpretation of DNA determinations in tissue sections is complicated, since the amount of DNA per slice of nucleus depends on the position of this slice within the nucleus (7). This problem can be circumvented to some extent by taking thick sections (5-8 pm) (6) and correcting for thickness (5), but in most tissues it is impossible then to analyze single nuclei due to overlap. In thin sections the absence of overlap allows one to perform DNA measurements on slices of single nuclei, but then the relation between the amount of DNA per slice and the amount of DNA per whole nucleus is still unclear. A method that allows the relation of the DNA in collections of nuclear sections to the DNA in whole nuclei is described. MATHEMATICAL BACKGROUNDFor the calculations an idealized tissue model is used; it is composed of cells with spherical nuclei homogeneously filled with a DNA solution and cut in infinitesimally thin sections. DNA Content of Sections of Spherical NucleiFor a plane at a distance, r < R, from the centre of the sphere with radius, R, the intersection of plane and sphere is a circle with radius m, and hence with a surface area A(r) = a (R2 -r2). When N is the total amount of DNA, then the DNA content of a slice of a (small) thickness, t, taken at a distance, r, from the centre of the sphere will be: D = (volume density of DNA) x (volume of slice)--radius per nuclear section are independent of nuclear size but depend on total DNA content. The distribution of the total DNA content of nuclei in a section can be estimated from such a histogram. The results of the measurements of a Feulgen-stained rat liver section are described.