Formation of 5-hydroxykynurenine and 5-hydroxykynurenamine from 5-hydroxytryptophan in rabbit small intestine

In order to clarify the role of indoleamine 2,3-dioxygenase [indole:oxygen 2,3-oxidoreductase (decyclizing), EC 1.13.11.17] in the metabolism of serotonin, DL-5-hydroxy[methylene-(14)C]tryptophan, a precursor of serotonin, was incubated with slices of rabbit ileum. Resulting metabolites were separated by DEAE-cellulose column and polyamide column chromatography and identified by various chromatographic techniques and enzymatic analysis. Metabolites obtained in significant amounts were serotonin, 5-hydroxyindoleacetic acid, 5-hydroxytryptophol, 5-hydroxykynurenine, 5-hydroxykynurenamine, and 4,6-dihydroxyquinoline, representing 13.2, 15.8, 7.0, 21.9, 1.3, and 2.6% of the total metabolites, respectively. The first three compounds were previously reported to be major metabolites produced from 5-hydroxytryptophan by the action of aromatic L-amino acid decarboxylase and monoamine oxidase, whereas the last three are formed by the cleavage of the indole ring by the action of indoleamine 2,3-dioxygenase. In the presence of pargyline, a monoamine oxidase inhibitor, the major metabolites obtained were serotonin, 5-hydroxykynurenine, and 5-hydroxykynurenamine, representing 29.6, 26.6, and 5.4% of the total metabolites, respectively. In the presence of RO4-4602, an aromatic amino acid decarboxylase inhibitor, 5-hydroxykynurenine was the sole major product. These results strongly suggest that the newly discovered metabolic pathway involving the cleavage of the indole ring of 5-hydroxytryptophan operates in vivo to a significant extent and that indoleamine 2,3-dioxygenase plays an important role in the regulation of serotonin levels in the small intestine of the rabbit.     

C5a-C5aR在脓毒症中的作用

脓毒症中补体系统的过度激活导致大量C5a的产生,并诱导其受体(C5aR)在细胞上的表达异常,C5a-C5aR相互作用调节炎症介质的表达、干扰凝血通路和诱导中性粒细胞功能障碍,最终导致器官功能损伤.     

体外培养的男性外生殖器皮肤成纤维细胞单层5α-还原酶活性测定

目的　提高临床对两性畸形患者的诊断和治疗水平。方法　以体外培养的男性外生殖器皮肤成纤维细胞单层为５α还原酶活性测定材料,３ Ｈ睾酮（ Ｔ） 为底物,经薄层层析法分离产物３ Ｈ去氢睾酮（ Ｄ Ｈ Ｔ） ,然后,结合蛋白质含量计算５α还原酶活性。结果　建立了稳定可靠的５α还原酶测定方法。批内和批间变异系数分别为６ ．４ ％ 和８ ．９ ％ 。总回收率为９１ ．５ ％ 。８ 例正常人５α还原酶活性为（７ ．００ ±９ ．４１）ｐｍ ｏｌ·ｍｇ － １·ｈ － １ （１ ．０８ ～２３ ．２１ｐ ｍｏｌ·ｍ ｇ － １ ·ｈ － １ ） 。结论　正常人之间５α还原酶活性存在较大变异。     

Disposition of 5-aminosalicylic acid by 5-aminosalicylic acid-delivering compounds

The disposition of 5-aminosalicylic acid (5-ASA) from 5-ASA-delivering drugs was studied in eight healthy volunteers. Time-related urinary excretion and faecal excretion of 5-ASA and acetyl-5-ASA were measured after a single oral dose of the azo compounds sulphasalazine and olsalazine, of the slow-release compounds Pentasa, Asacol, and Salofalk, and of plain 5-ASA. Plain 5-ASA was rapidly excreted into urine and had a low faecal recovery, indicating fast absorption proximally in the intestine and little availability to the colon. After ingestion of both azo compounds and slow-release compounds, urinary excretion of 5-ASA was markedly delayed and reduced, and faecal excretion was enhanced. At all points of time there was a significant but not very marked difference in urinary excretion of 5-ASA after ingestion of the azo compounds and the slow-release compounds, in favour of the azo compounds. A significantly larger proportion of the ingested 5-ASA, moreover, was excreted in faeces after intake of azo compounds as compared with slow-release compounds.     

Transformation kinetics of the 5'-chloro-5'-deoxy analogue of arabinosylcytosine

5'-Chloro-5'-deoxy arabinosylcytosine (Cl-araC) is a more lipophilic analog of the clinically used drug--arabinosylcytosine (araC). The resistance toward the enzyme cytidine-deaminase action was described as an characteristic feature of this synthetic nucleoside. The kinetics of the Cl-araC transformation in acid and alkaline solutions was studied at various temperatures. When compared with parent compound araC, the chlorine atom at the 5' position of the nucleoside sugar moiety increases the Cl-araC stability. The chlorine atom stabilizing effect is higher in acidic conditions. Cl-araC increased stability, antileukemic activity accompanied by higher lipophilicity confirm the fact that Cl-araC belong among interesting compounds from the point of view of cancer chemotherapy.