Percoll density gradient centrifugation was used for isolating large quantities of bradyzoites of Sarcocystis suicanis, which were used for enzymatic analysis. Crude extracts of bradyzoites contained activities suggestive of several acid hydrolases. Levels of acid and alkaline phosphatase were higher than those of beta-N-acetylhexosaminidase and beta-galactosidase. Acid phosphatase was purified 156-fold with an overall recovery of 54% using DEAE-Sepharose 4B and Sephadex G-200 chromatography. The partially purified enzyme was not a glycoprotein and had a molecular weight of approximately 170,000. The enzyme was markedly inhibited by Cu++, Hg++, and iodoacetamide, suggesting the presence of a sulfhydryl group. Sodium tartrate caused strong inhibition of the enzyme. The acid phosphatase of S. suicanis appears to be a unique enzyme that cannot be classified under high or low molecular weight acid phosphatases of widely diverse origin.

SummaryThe administration of desiccated thyroid inhibited the uptake, but not the release, of I131 (in five millicurie doses) by the metastases of a thyroid adenocarcinoma.The desiccated thyroid was apparently responsible for a marked and sustained reduction in the size of the pulmonary and subcutaneous metastases.It is suggested that in cases of thyroid carcinoma it may be better to try treatment with desiccated thyroid before I131 therapy, rather than after it.

Epidemics of infectious diseases, such as the great plague of London, partly erased by the great fire, were of mysterious origin until Louis Pasteur (Figure 1) introduced the correct Germ Theory of Disease [1], in opposition to the prevailing theory that life was generated spontaneously in decaying organic matter. Lionel Whitby [2] initiated brilliant study of medical bacteriology, which was carried on by others as described by Baron [3], producing amazingly detailed knowledge of Microbiology. The Immunity SystemThis exists for defence against infectious diseases, as well described by Arthur Silverstein in William Paul's classic textbook [4], the description of Nobel Prize highlights summarising major advances well. Autoimmune DiseaseThe steps involved in the discovery of the existence and the pathogenesis of the autoimmune diseases are shown in Table 1. As antibodies that fitted specific germs had been discovered, it was natural to think that they were built on a template of antigen. However, Miescher discovered the structure of DNA (Deoxyribonucleic Acid). Then Watson and Crick [5,6] discovered that the order of four bases in a very long double helix provides the genetic code for man and other creatures. Armed with this revolutionary knowledge, Niels Jerne [7] realised that cells are factories that can swiftly convert DNA to RNA to polypeptide, and proposed the Selection Theory,