Chemistry: analytical and immunological testing – Pregnancy or ovulation
Patent
1982-02-05
1984-02-21
Marantz, Sidney
Chemistry: analytical and immunological testing
Pregnancy or ovulation
G01N 3352, G01N 3376
Patent
active
044330570
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a chemical reagent indicator for the in vitro diagnosis of pregnancy in a female mammal, and also to the method of preparing and the method of utilizing such indicator.
It is well known to rely on the presence of human chorionic gonadotropin (H.C.G.) in the urine or serum of expectant mothers beyond the 24th day of pregnancy, with a maximum concentration between the 40th and the 60th day, for diagnosing the state of pregnancy.
Initially, biological lab tests have been carried out by using animals such as rats and rabbits.
Though the accuracy of these tests is satisfactory, the time and means necessary for accomplishing them, and consequently their cost, are rather excessive, thus making the procedure inadequate for a generalization.
Immunological tests have also been proposed which consist in determining a reaction between gonadotropin and its antibodies. These tests are also satisfactory from the point of view of precision, but suffer from the same inconveniences as biological tests: they are time-robbing, difficult to implement, and expensive.
It is therefore necessary to develop a different method which is at the same time rapid, accurate and economical, and also capable of affording an easy interpretation of the result even by the unskilled layman.
The U.S. Pat. No. 3,595,620 filed by Gordon on Oct. 28, 1968 discloses and claims a chemical reagent acting as an indicator in the in vitro diagnosis of pregnancy, by imparting a specific color to the urine when added thereto.
This reagent consists either of bromocresol purple of chlorophenol red in a buffer solution having a pH value of 6 and comprising monobasic potassium phosphate and sodium hydroxide. chlorophenol red.
The reagent is criticized on account of the small discrepancy between the color due to a negative reaction and the color due to a positive reaction, which discrepancy may drop to about one-hundred Angstroms, with the possibilites of misinterpretation.
Besides, it seems that the amount of reagent implemented does not affect the result appreciably.
It is the primary object of the present invention to improve the results obtained with a Gordon-type reagent by increasing the discrepancy between the color due to a negative reaction and the color due to a positive reaction.
Besides, experience teaches that the positive test color was reinforced when the colorimetric agent utilized was a mixture of halogenated cresol (such as bromocresol purple) and halogenated chlorophenol (such as chlorophenol red), the two components producing on each other a synergetic effect controlling the degree of coloration of the positive test, the best results being obtained when the ratio of bromocresol purple to chlorophenol red was in the range of about 55% to 45% by weight, and preferably in the ratio of 53% to 47% by weight.
These tests produced a great number of wrong and dubious results in which it would have been impossible to give an affirmative answer in one or the other direction, had the sound answer not been known beforehand.
In all these cases the verifications made showed that the urines had an abnormally low pH value or an abnormally high pH value, and consequently that the urines of a non-pregnant woman (i.e. a test of which the result should normally be definitely negative) turned to the range of purple red tints, close to the range of tints which should normally correspond to the positive test.
The applicant observed that a first requirement for obtaining true results was to change the urine pH so that it ranges between 4 and 5.
Now, there is at least one case in which this acid-alkalimetry factor displays a strongly basic trend, namely when the woman has previously ingested a steroid drug, for example a contraceptive drug.
In his U.S. Pat. No. 3,595,620, Gordon, far from thinking that the presence of this type of hormone might alter the test result, had on the contrary the idea of utilizing this property for detecting the omission of taking a contraceptive pill.
It is therefore the primary object of the present inven
REFERENCES:
patent: 3226196 (1965-12-01), La Vietes
patent: 3248173 (1966-04-01), Stauch
patent: 3298787 (1967-01-01), Fossel
patent: 3345138 (1967-10-01), Eberhard et al.
patent: 3595620 (1971-07-01), Gordon
patent: 3813222 (1974-05-01), La Vietes
Chemical Abstracts, 92: 37296b (1980).
Chemical Abstracts, vol. 7, No. 2, 1971, No. 14558y.
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