(1) The Preparation and Value of a Standardised Modification of the Laughlen Test for Syphilis. (2) Investigations on Syphilis Antigen: (a) The Value of Soya Bean Extracts. (b) The Significance of the Diaminomonophosphatide Sphingomyelin

Stevenson, John Simpson (1948) (1) The Preparation and Value of a Standardised Modification of the Laughlen Test for Syphilis. (2) Investigations on Syphilis Antigen: (a) The Value of Soya Bean Extracts. (b) The Significance of the Diaminomonophosphatide Sphingomyelin. PhD thesis, University of Glasgow.

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It is probably true to say that the merits of the precipitation tests for syphilis depend more on their particular methods of performance than on the intrinsic qualities of their individual antigens, which are all similar and in many cases identical. Thus the value of the Laughlen Test will depend upon whether its method of performance is convenient for the conditions under which the test is to be used. The results obtained in Section One of this thesis have shown that the present modification of the Laughlen lest fulfils this requirement in that it is completely reliable for the detection of syphilis in the untreated case, it may be carried out within ten minutes or less and it possesses a simplicity which may be claimed as unequalled. Further, this version of the reaction has been standardised in such a way that the reagent may be reproduced in an exact scientific manner. The large-scale testing for which the test was originally intended, if therefore, seems to present the ideal field for this modified Laughlen Test: the numerous specimens from routine investigations, blood banks, ante-natal clinics, etc., can be tested easily and rapidly with the assurance that no positive serum will be missed, or at least none which would react positively with the wassermann Reaction. As pointed out previously, this speed and reliability enaole the test to be applied in several ways; it may be used as the preliminary screen test in a large serological centre in order to reduce the number of sera to be tested by the wassermann Reaction; it is eminently suited for use as the standard diagnostic test in a "branch" laboratory: it is invaluable as a means of carrying out a test for syphilis at short notice since there is no need for any special preparation, the reagent being ready for immediate use from the moment it is 36 hours old until several months from the time of manufacture. In Section Two it has been shown that this modified Laughlen lest possesses another very useful and interesting feature, i.e., it may be used as a most convenient method of carrying out research. In this way it has been demonstrated that the soya bean contains a substance similar to and reacting in the same way as syphilis "antigen" and although this substance presents problems of extraction, the fact that the soya bean is now cultivated on a large scale in many parts of the world gives weight to the suggestion that in this connection the plant is worthy of further research as it appears probable that in the soya bean there may be found substances which could be used with advantage as antigens in serological tests for syphilis; that these substances exist is certain, as has been proved in the present investigation, but there remains the problem of establishing standardised methods of extraction to produce antigen of high potency. The investigation of sphingomyelin was of a more academic nature, being an attempt to probe the innermost structure of syphilis antigen, and here again the modified Laughlen Test provided a convenient method of conducting the enquiry. Even the somewhat negative results of the investigation do not detract from the preliminary argument that the known solubilities and insolubilities of sphingomyelin almost certainly establish it as a constituent of syphilis antigen and this argument is further strengthened by the results of the work on the soya Dean where, it will be remembered, the best results were obtained with extracts made from ether-insoluble material. The purity of the sphingomyelin employed in the investigation leaves little doubt that the influence of this phosphatide on the activity of syphilis antigen is represented by the present findings i.e., that it is concerned with sensitivity but not with specific reactivity. It is not proposed to attempt an explanation of this property but the absence of glycerol in the sphingomyelin molecule might suggest the implication of the substituted base, spningosine. In conclusion, the reports of the three investigations which form this thesis may be summed up thus:- By an examination of the several components which constitute its reagent, the Laughlen Test for syphilis has been modified in such a way that it represents a standard, rapid and reliable exclusion test for the diagnosis of that disease. In addition, it has been shown how this version of the reaction was used as a simple method of carrying out original research: this revealed a potentially significant source of syphilis antigen in the soya bean and indicated that the sensitivity of syphilis antigens in general may be to some extent under the control of the phosphatide sphingomyelin.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Keywords: Medicine, Microbiology
Date of Award: 1948
Depositing User: Enlighten Team
Unique ID: glathesis:1948-79703
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 04 Mar 2020 15:24
Last Modified: 04 Mar 2020 15:24
URI: https://theses.gla.ac.uk/id/eprint/79703

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