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Standardization of the measurement of amyloid degrading activity (ADA) by diffusion of serum in amyloid-impregnated agar plates may either indicate or exclude with reasonable certainty the presence of systemic AA amyloidosis. In certain cases, it may obviate the need for a diagnostic biopsy. The sera of 38 patients with systemic amyloidosis were tested and compared with sera of 38 controls matched for age, serum creatinine and albumin blood levels, and with sera of 48 additional controls with the same basic diseases as the amyloidotic patients but without amyloidosis. The difference between ADA of amyloidotic and control patients was significant, with no overlap in the range of activity between the two groups. A positive correlation was found between ADA and serum albumin concentration in the nonamyloidotic matched controls but not in patients with amyloidosis. Our data do not support the view that the decline in ADA of sera of amyloidotic patients is due to hypoalbuminemia.

Dimethyl sulfoxide was administered intravenously for 60 days to twenty mice with casein-induced amyloidosis. Partial or total disappearance of amyloid deposits occurred in all treated animals. The urine of these animals contained a substance from which amyloid fibrils could be synthesized. A control group of mice with casein-induced amyloidosis given saline injections showed massive amyloid deposition in the liver and in the spleen at the end of the experiment. Neither the urine of these mice nor the urine of normal control mice treated with dimethyl sulfoxide contained substances from which amyloid fibrils could be synthesized. It is our assumption that dimethyl sulfoxide treatment of mice with amyloidosis resulted in a break up of amyloid fibres into small subunits which were excreted in the urine.

In vitro experiments have shown that the amyloid degrading activity of amyloidotic sera could be restored by ascorbic acid, citric acid and by EDTA. It was therefore decided to test the influence of Vitamin C on experimental murine amyloidosis. Amyloidosis was induced during 14 days in three groups of 60 animals each. The first group received Vitamin C in the drinking water, as 3.5% solution, throughout the entire experimental period. Vitamin C was given to the second group after the induction of amyloidosis, while the control group received water alone. On the tenth, 17th, and 20th post induction days, 15 mice of each group were sacrificed. Their spleens were examined for the presence of amyloid. On the 17th day no amyloid was found in nine mice (out of 15) of the first group and in eight of the second. Small deposits were observed in five and three animals respectively. However, in the control groups giant deposits of amyloid were found in ten out of 15 animals. Amyloid degrading activity (ADA) of murine serum was examined in untreated, amyloidotic and Vitamin C treated animals. In healthy animals the ADA is unaffected by Vitamin C. In amyloidotic mice which have very low ADA initially, the addition of Vitamin C significantly increases the ADA. These results may possibly indicate that the in vitro effect of Vitamin C on amyloidotic sera is also expressed in an in vivo experimental model.

Insulin, calcitonin and parathyroid hormone subjected to one of two procedures-acidification and heating or incubation with mouse kidney lysosomal extracts-assumed a nonbranching fibrillar structure, 7 to 10 nm in diameter. The preparations showed green birefringence after Congo red staining. The in vitro synthesis from different hormonal polypeptides of fibrils, fulfilling the criteria for the identification of amyloid, indicates that these criteria are related to conformational rather than to compositional properties, and suggests that these hormones may provide the subunit of the amyloid formed in the corresponding endocrine organs.

ADA of human serum was demonstrated and investigated with an agar gel diffusion technique using amyloid-impregnated agar plates. Sera of 20 healthy adults, 40 patients with AA-amyloidosis, and 86 nonamyloidotic patients were tested. The presence of an ADF, showing enzymatic properties and strongly bound to albumin, was demonstrated in normals and amyloidotic and nonamyloidotic patients. ADA in the serum of amyloidotic and cirrhotic patients was markedly decreased due to the presence of an inhibitor of ADF. ADA of amyloidotic sera was restored to normal by EDTA, citric acid, and ascorbic acid. The ADA of 16 FMF patients and four of 34 patients with rheumatoid arthritis without amyloidosis was intermediate between normal and amyloidotic values, indicating the presence of lADF at low concentrations in these patients. These findings suggest that amyloid is a normal protein metabolite, possibly with a high metabolic turnover. Accumulation of amyloid may be caused by decrease of the ADA of the serum by its inhibitor, rather than by accelerated production.

Amyloid was obtained in recipient mice by implantation into their peritoneal cavity of a dialysis bag containing spleen cells obtained from donor mice which were treated with casein for 6 days and while no amyloid was found in their implanted spleens. The transplantations were performed with 2 cell systems, one containing whole spleen suspension and the other washed cells. Amyloid was obtained in the recipient mice within 6 days after the implantation and in a more massive quantity than in mice treated by casein for a similar period.

In systemic amyloidosis, the rare instances of recovery following the successful treatment of a predisposing disease present a challenge in the management of an otherwise fatal disorder 1,2. Notwithstanding, experimental endeavor has been directed largely toward unravelling the nature of amyloid and its pathogenesis rather than the biological mechanism by which this fibrillar protein may be removed from the tissues 3. The following experiments indicate that normal human serum contains a heat-stable component capable of degrading amyloid in vitro.Procedure. In principle, one portion of a standard suspension of water-soluble amyloid 4 was incubated with two portions of human serum in a test tube for 2 hr at 37°. Following incubation the precipitate obtained by centrifugation for 30 min in a cooled PC-2 Sorvall Centrifuge at 15,000 rpm was collected, twice washed in cold saline, and recentrifuged as above, resuspended in normal saline, and its total protein content determined by the Biuret method at 555 nm. ...

Amyloidosis was induced by casein injections in mice allocated to glucose, purina and casein dietary regimens. Amyloid was not found in the glucose fed mice. By contrast, amyloid was present in the spleen of purina fed animals and in the spleen, liver and kidney of those fed casein. It seems therefore that adequate protein intake is essential for the consummation of an amyloidogenic stimulus.