Hemochromatosis is a syndrome which, when fully expressed, is manifested by melanoderma , diabetes mellitus, and liver cirrhosis, with iron overload involving parenchymal and reticuloendothelial cells in many organ systems. This clinical presentation may arise as a consequence of either hereditary or acquired abnormalities of iron overload, although the mechanisms are quite different. In hereditary hemochromatosis (also known as primary, or idiopathic, hemochromatosis), increased intestinal iron absorption leads to excessive accumulations of iron, throughout the body, particularly in parenchymal cells. In secondary forms of iron overload including transfusional hemosiderosis, alcoholic cirrhosis, thalassemia, sideroblastic anemia, and porphyria cutanea tarda, iron accumulates in the reticuloendothelial system initially, but with increasing amounts of total body iron, excessive iron deposits eventually accumulate in parenchymal cells throughout the body producing a picture indistinguishable from hereditary hemochromatosis. In this article, the course, prognosis, and therapy of iron overload will be reviewed in detail. Clinical and experimental data concerning the pathogenesis of the different forms of iron overload will be examined critically. In particular, information relating to possible abnormalities of reticuloendothelial function, intestinal mucosal iron transport, and alterations in serum and tissue isoferritin patterns in hereditary hemochromatosis will be analyzed, and possible directions for future research will be suggested. The mode of inheritance and linkage with the major histocompatibility (HLA) complex will be discussed. Theories on the pathogenesis of tissue damage by excess iron will be evaluated. Methods for measuring the extent of iron overload in clinical practice will be described, including measurements of serum iron, serum ferritin, iron absorption, cobalt excretion, desferrioxamine excretion, liver biopsy and tissue iron determinations, and HLA typing. Finally, unresolved problems in the understanding of the disease process, diagnosis, and therapy will be delineated.

and properties of enzymes involved in the propionic acid fermentation. J. Bacteriol. 87:171-187. 1964.-Chromatographic procedures are described for the separation and purification of phosphotransacetylase, acetyl kinase, malic dehydrogenase and coenzyme A (CoA) transferase. Purity of the enzymes was judged by homogeneity in an ultracentrifuge and by specific activity. Phosphotransacetylase was obtained 85% pure with a specific activity of 27.1. The preparation of acetyl kinase was a homogeneous protein with a specific activity of 531. The malic dehydrogenase likewise was homogeneous with a specific activity of 938. The CoA transferase, which was about 56% pure with a specific activity of 42.6, is the purest preparation of this enzyme yet described. The pH optimum was 6.5 to 7.8, and the Km for succinyl-CoA in the transfer of CoA to acetate was found to be 1.3 X 10-4 M; for acetate, in the same transfer, the Km was 7.0 X 10-3 M; for succinyl-CoA to propionate it was 6.8 X 10-5M, and for propionate, in the same reaction, 6.2 X 104 M. Methods are described for the enzymatic production of methylmalonyl-CoA, malonyl-CoA, propionyl-CoA, acetyl-CoA, and succinyl-CoA. The role of these enzymes in the propionic acid fermentation as well as the possible mechanism responsible for the high yields of adenosine triphosphate from glucose are considered. The formation of propionate by propionibacteria has been extensively investigated, and the pathway is known to involve a number of enzymes which have been purified and studied. These include methylmalonyl-oxaloacetic trans

A young woman, successfully treated for Hodgkin's disease with radiation and MOPP chemotherapy, incurred a devastatiq stroke months after radiation therapy to the neck and other areas. There was no premonitory clinical history of cerebrovascular attacks. Autopsy showed unilateral thrombotic occlusion of the internal carotid artery unassociated with neoplastic or fibrotic annular constriction of the vessel. There was medial thickening and fibroblastic proliferation within the carotid artery. Areas of focal elastic membrane degeneration involved the cervical portions of the carotid. Thrombus was organized to the damaged vessel wall and was propagated into the intracranial vessels. Aneurysm formation and arterial hemorrhages were absent. These vascular changes occurred in an area of extensive radiation (7200 rads). Pathoanatomical studies in this patient indicate that radiation-induced vascular changes were associated with a "delayed" stroke.