Human megakaryocyte ploidy.

We reviewed the literature concerning the history of determination of the ploidy of human megakaryocytes and its relationship with diseases. The ploidy of rabbit megakaryocytes was analyzed by microspectrophotometry in 1964, and the analysis of the ploidy in human megakaryocytes was first performed in 1968. Presently, microphotometry and flow cytometry are the primary methods for the evaluation of the ploidy, but they have their merits and demerits. In the ploidy of human megakaryocytes, a peak has often been reported at 16N in healthy individuals, and the next peaks have been observed at 32N and 8N. The results of ploidy analyses have been reported by many investigators to be comparable between patients with idiopathic thrombocytopenic purpura and normal subjects, but various shifts of the peaks have also been documented. The ploidy is often reported to shift to a larger ploidy class in polycythemia vera and essential thrombocythemia, but it has invariably been reported to shift to a smaller class in chronic myelogenous leukemia. In reactive thrombocytosis, the ploidy pattern was reported to be the same as that in normal individuals by some investigators but to shift to a larger ploidy by others. These differences are considered to be due to heterogeneity of the subjects. In myelodysplastic syndrome, the ploidy shifts mostly to a smaller class, but it may show various patterns. We also reviewed the ploidy in other rare hematological disorders, the relationships of the ploidy with diabetes mellitus and atherosclerotic disorders, and its changes in the ontogeny. Details of the mechanism of polyploidization and its biological significance remain unknown, and further advances in the studies of these topics are anticipated.     

Human prothrombin activation.

Human prothrombin has been purified from American Red Cross Factor IX concentrates. Studies of the activation of the human prothrombin with the use of sodium dodecyl sulfate electrophoretic analysis of activation products indicated that human prothrombin activation is similar to bovine prothrombin activation. Molecular weight analysis of human prothrombin and intermediated by sodium dodecyl sulfate co-electrophoresis with bovine prothrombin and its intermediates resulted in molecular weights of 70,000 for prothrombin, 51,000 for intermediate 1, 41,000 for intermediate 2, 23,000 for intermediate 3, and 13,000 for intermediate 4. Amino acid compositions of human prothrombin and intermediates are similar to those for bovine prothrombin and intermediates. NH2-terminal sequence studies of human prothrombin, intermediates, and alpha-thrombin A and B chains placed the intermediates in the parent human prothrombin molecule as described for the bovine system. Intermediate 3 is the NH2-terminal of prothrombin, and intermediate 1 is the COOH-terminal segment of the zymogen. Intermediate 4 is the NH2-terminal of intermediate 1. Intermediate 2', the immediate precursor of alpha-thrombin, is the COOH-terminal segment of intermediate 1. In general, a high degree of homology in the primary structure of prothrombin and intermediates was observed between the human and bovine system. The NH2-terminal sequences of human intermediate 2' and alpha-thrombin A chain are identical. However, human intermediate 2' isolated in a manner identical with that used for the isolation of bovine intermediate 2 is homologous with bovine intermediate 2, beginning with residue 14.     

Human dietary change.

The transition from hunting and gathering to agriculture and animal husbandry in the Near East and Mediterranean Region began some 12,000 years ago. The ecological changes associated with this change are known to have been related to higher levels of stress from undernutrition and infectious disease. Certain pathologies found in human skeletal remains from this time are indicative of anaemia and osteoporosis, although it is not clear whether they had clear nutritional aetiologies. In this paper, dietary changes associated with changes in subsistence practices in this region are described. In addition, quantitative modelling of possible patterns of dietary and nutrient intakes of adult males before, and soon after, the establishment of agrarian economies is used to examine the proposition that the skeletal pathologies porotic hyperostosis, cribra orbitalia and porotic hyperostosis may have been due to nutritional deficiencies. The results suggest that protein deficiency was only likely if subjects were suffering from chronic energy deficiency (CED) and their diet contained no meat. Dietary calcium deficiency was possible after the transition to cultivation and animal husbandry, in the presence of moderate or severe CED. Anaemias, although present after the transition, were unlikely to have had dietary aetiologies, regardless of the severity of CED.     

Human granulocyte ribonuclease.

Human granulocytes contain an RNase which is thermostable at pH 4.2 and thermolabile at pH 8.5. It has a pH optimum at 6.5. It exhibits highest preference for the secondary phosphate esters of uridine 3′-phosphates. It has no action on uridine 2′: 3′-cyclic phosphates. Poly (A) and poly (G) are inert to its action. Its rate of hydrolysis of poly (C) is about 1% of that of poly (U). It differs from bovine pancreatic RNase and human serum RNase. Because of its unique specificity, this enzyme might serve as a biochemical marker in certain granulocyte disorders.