P-aminophenylacetic Acid Research Articles

Gonadotrope function in ovariectomized ewes actively immunized against gonadotropin-releasing hormone (GnRH).

The gonadotrope cells of the ovine anterior pituitary were insulated from hypothalamic inputs by imposing an immunologic barrier generated by active immunization of ovariectomized ewes against gonadotropin-releasing hormone (GnRH) conjugated to keyhole limpet hemocyanin (KLH) through a p-aminophenylacetic acid bridge. All GnRH-KLH animals immunized developed titers of anti-GnRH that exceeded 1:5000. The antisera were specific for GnRH and cross-reacted with GnRH agonists modified in position 10 to an extent that was less than 0.01%. Ewes actively immunized against GnRH-KLH displayed levels of basal and GnRH agonist-induced gonadotropin secretion that were markedly lower (p less than 0.05) than comparable parameters in ewes actively immunized against KLH. In contrast, basal and thyrotropin-releasing hormone (TRH)-induced prolactin (PRL) secretion were not compromised by active immunization. Immunization against the GnRH-KLH conjugate, but not KLH alone, prevented expression of the positive feedback response to exogenous estradiol (E2). Pituitary stores of immunoactive luteinizing hormone (LH) and follicle-stimulating hormone (FSH) were significantly (p less than 0.001) reduced in ewes immunized against GnRH-KLH but stores of PRL were not affected by such immunization. Further, the biopotency of the residual LH stores in tissue of animals from the anti-GnRH group was significantly (p less than 0.05) lower than LH biopotency in anti-KLH animals. Serum levels of LH in anti-GnRH ewes were restored by circhoral administration of a GnRH agonist that did not cross-react with the antisera generated. Pulsatile delivery of GnRH agonist in anti-GnRH ewes significantly (p less than 0.05) elevated serum LH within 48 h and reestablished LH levels comparable to anti-KLH ewes within 6 days of treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Mutagenic potential of some chemical components of dental materials.

Abstract Chemical compounds that are used in dental materials or related structurally to compounds that are found in dental materials were tested for bacterial mutagenicity by means of the Ames Test. The results of spot tests and plate incorporation tests indicated that 8 of the compounds were not mutagenic. These same procedures showed that one of the chemicals, p-aminophenylacetic acid, is weakly mutagenic. The data also indicated that the addition of liver extracts containing microsomal enzymes enhanced the mutagenic activity of p-aminophenylacetic acid.

Penicillin derivatives of p-aminobenzylpenicillin.

THE formation of p-aminobenzylpenicillin was reported by Corse, Jones, Soper, Whitehead and Behrens1; but no material was isolated. Brewer and Johnson2 later obtained partially purified material by using p-aminophenylacetic acid as precursor; but no details of yields or purity were given. The work reported here was carried out in order to obtain p-aminobenzylpenicillin for use as the parent compound of a series of derivatives. Tosoni, Glass and Goldsmith3 have since reported the preparation of crystalline p-aminobenzylpenicillin by hydrogenation of p-nitrobenzylpenicillin and the preparation of certain N-acyl derivatives.

Relative Acidity and Basicity of Sulphanilamide and p-Aminobenzoic Acid

SINCE no determination of the relative acidic or basic dissociation constants of sulphanilamide appears to have been published, this drug was potentio-metrically titrated against N/1 hydrochloric acid followed by N/1 sodium hydroxide. p-Aminobenzoic acid and p-aminophenylacetic acid were treated similarly for purposes of comparison. In each case, a solution of freshly recrystallized, pure material (0.0005 gm. mol. in 20 ml. of water) was titrated in a beaker fitted with a stirrer, glass electrode and potassium chloride agar bridge connected to a calomel half-cell and a Leeds and Northrup universal pH potentiometer assembly. The results are shown in the accompanying figure and the derived (uncorrected) dissociation constants are given in the table.

Acetylation as a physiologic reaction.

After the ingestion of para-amino phenyl acetic acid by human beings it was found that this substance was detoxicated by acetylation of the amino group. When fed to rabbits, acetic acid was also employed as the detoxicating agent and p-acetyl aminophenyl acetic acid was excreted in the urine. When the p-amino phenyl-acetic acid was fed to dogs, however, the amino group remained free and the detoxication of the compound was accomplished by combining with glycocoll. Ortho, meta and para amino benzoic acids were ingested by human beings then fed to dogs and rabbits. All three compounds were excreted unchanged in the urine of the dog. The ortho amino benzoic was excreted unchanged by the human being and rabbit, but the meta and para amino benzoic were acetylated by the human being as well as by the rabbit. Ortho acetyl amino benzoic acid was prepared and fed to the dog and rabbit as well as taken by a human subject. The acetyl derivative was found to be non-toxic, and was in each case rapidly excreted unchanged. There was in no case a glycocoll compound formed as reported by Salkowski after feeding meta amino benzoic acid to a human being, dog and rabbit.