[Urocanic acid content of the epidermis of diabetics]. / Soderzhanie urokaninovoi kisloty v épidermise kozhi bol'nykh sakharnym diabetom.

A degree of a decrease in the content of urocanic acid in washes-off from the skin surface of patients with decompensated diabetes mellitus depends on a period and gravity of disease that may be indicative of disorders of the adenylate cyclase system (or one of its links). Change in the content of urocanic acid in the epidermis of patients with diabetes mellitus treated with the Biostator apparatus, correlates with change in the content of glucagon and blood sugar. The authors discuss a possibility to use the test of urocanic acid determination for the prediction and assessment of the efficacy of therapy of patients with diabetes mellitus.

[Evaluation of the hepatotoxic activity of several chlor-nitro derivatives of benzoic acid]. / Otsenka gepatotoksicheskogo deistviia nekotorykh khlor- nitroproizvodnykh benzoinoi kisloty.

Hepatotoxic effects of 4-chloro-3-nitrobenzoic acid (x-NBA), 3-nitrobenzoic acid (NBA) and 4-chlorobenzoic acid (CBA) were studied at the doses corresponding to LD50, 1/10 LD50 and 1/50 LD50. The toxic effects were estimated by monitoring alterations in activity of protein-synthesizing system in liver tissue and by the analyses for the presence in blood serum of two tissue-specific cytoplasmic enzymes of liver cells--urokaninase (EC 4.2.1.49) and histidase (EC 4.3.1.3). Single peroral administration of the toxic substances at a dose equal to LD50 led to dissimilar alterations in synthesis of liver proteins: activation within 0.5-5 hrs, distinct increase up to the maximal value within 60 hrs, with a gradual decrease approaching the control values within 8 days. Urokaninase and histidase activities were found in blood serum within 8 hrs after the intoxication, reaching the maximum within 15 hrs and exhibited the constant level during 25 hrs. Then the enzymatic activity was gradually decreased but it did not reach the control values within 70 hrs. After daily peroral administration of these toxic substances at the doses corresponding to 1/10 LD50 and 1/50 LD50, only the first dose inhibited the protein synthesis within 2 weeks. Within this period the enzymes studied were not found in blood serum. Distinct inhibition of the protein synthesis was observed within 4 weeks after administration of both these doses. In this case enzymatic activity was present in blood serum (up to 3 mumole/I L blood serum). Within 2 months after administration of these preparations the alterations studied were the most distinct.

[Purification, properties and regulation of urocaninase from rat liver]. / Ochistka, svoistva i reguliatsiia urokaninazy pecheni krys.

Urocaninase (EC 4.2.1.4.9) from rat liver homogenate has been purified, using protein precipitation at pH 4,8, ammonium sulfate fractionation, gel-filtration through Sephadex G-200 and chromatography on DEAE-cellulose. Upon DEAE-cellulose chromatography urocaninase is separated from the proteins possessing the activity of 3',5'-AMP-dependent protein kinase. The purified enzyme becomes activated after addition of ATP and exogenous protein kinase or one of the fractions resulting from DEAE-cellulose chromatography. Using [gamma-32P]ATP, it has been shown that such activation is accompanied by incorporation of at least one phosphate residue into the enzyme molecule. The mol. weight of urocaninase as determined by gel-filtration is about 110 000. The Km value for urocanate is 15 . 10(-6) M, the isoelectric point lies at 5,6. The mechanism of regulation of the urocaninase activity in rat liver is discussed.

[Diagnosis of histidinemia through using the determination of urocanic acid in the sweat by an enzymatic method]. / Diagnostika gistidinemii s pomoshch'iu opredeleniia urokaninovoi kisloty v pote énzimaticheskim metodom.

A diagnosis of histidinemia was confirmed by estimation of urokaninic acid in sweat using highly purified preparation of urokaninase from rat liver tissue. The content of urokaninic acid was estimated by the method developed and by means of a known chemical method, which involved reduction of urokaninic acid with zinc in a medium containing HCL; seven children with histidinemia and ten healthy children were examined. The diagnosis of histidinemia was confirmed since the content of urokaninic acid was distinctly decreased in sweat of the imparied children as compared with the control group. The method developed was highly sensitive, reproducible and accurate.

[Regulation of urocaninase activity in the liver: role of 3',5'-AMP]. / Reguliatsiia aktivnosti urokaninazy v pecheni: rol' 3',5'-AMP

A dependence of rat liver urocaninase activity on the agents affecting the adenylate cyclase system was studied in vitro and in vivo. Urocaninase is considerably activated after the injection of glucagone, NaF, theophylline and 3',5'-AMP. Under conditions optimal for the protein kinase activity of phosphorylase the urocaninase of liver extracts was activated 7-fold on the average. The nezyme retains its activity after gel-filtration through Sephadex G-25 and is capable of inactivation in the presence of Mg2+ and of reactivation after addition of ATP and 3',5'-AMP. These data suggest a possibility of regulation of mammalian liver urocaninase activity by 3',5'-AMP-dependent phosphorylation of the enzyme. Derivatives of hypoxanthine (theophylline and caffeine) in concentration 10(-4) M activate urocaninase in liver extracts 2--3 and 1.5-fold respectively. The activation is probably not due to the 3',5'-AMP phosphodiesterase inhibition, since another phosphodiesterase inhibitor--papaverine--has no activating effect on urocaninase.