Abstract
Summary
The use of Abderhalden's test for pregnancy, employing the dialysis method and the ninhydrin color reaction has given positive results with each of 28 sera from pregnant women and with eight from women in the post-partum period, including one abortion. The test has never been negative in a known pregnancy. On the other hand, the serum of pregnancy reacts with tissues (kidney, heart, uterus) other than placenta. Also sera of two cases of nephritis, one of tabes and one of infection (carbuncle), and occasionally of some individuals in apparent perfect health have given the reaction with placenta and other tissues.
In the use of Abderhalden's dialysis method we have found the ninhydrin reaction far superior to the biuret reaction. It is also important that Schleicher and Schull's smaller dialysis sacks should be used rather than the fish skin membranes originally recommended.
Results as satisfactory as those obtained by dialysis are obtained by mixing tissue and serum in tubes and after incubating for 24 hours testing the filtrate obtained on coagulation by heat and acetic acid with ninhydrin.
Inactivation of the serum causes a great diminution in the degree of reaction, but does not cause it to disappear entirely. At zero temperature no reaction occurs. The power of a serum to cause the reaction persists when the serum is kept under proper conditions of temperature for at least 7 days.
As the result of our studies we feel that this test cannot be accepted as an accurate clinical method until it has been more thoroughly investigated and the possible sources of error corrected. This conclusion however applies only to Abderhalden's dialysis method and not to his optical method with which we have had no experience.
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