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.     

5 Autoantibodies

The number of autoantibodies associated with chronic liver disease continues to burgeon and characterization of these immunoreactivities will undoubtedly enhance understanding of the autoantigens that are targeted by cytodestructive immunocytes. Assays for the majority of these immunoserological species are not generally available and in most instances, assessments are restricted to individual laboratories with vested interests in characterizing a particular species.For clinical diagnosis and management of autoimmune liver disease, assays for ANA, SMA, anti-LKM1 and AMA are essential. This conventional armamentarium, however, must be upgraded on a regular basis to ensure availability and application of the most useful assays. Unfortunately, there are no formal mechanisms for improving the diagnostic resources and standardizing testing strategies. An important first step must be taken by the basic laboratories that advocate individual assay systems. These facilities must share methodologies and exchange serum samples so that the most clinically pertinent and cost-effective immunoserological batteries can be defined and promulgated. Industry can then respond to need and facilitate the commercialization of assays for general use.Currently, the assays that warrant dissemination are those that detect antibodies to the E2 subunits of the pyruvate dehydrogenase complex and antibodies to asialoglycoprotein receptor. Both assays have high diagnostic specificity and each reflects reactivity to an important target autoantigen of probable pathogenic importance. Each autoantibody species can supplant conventional assays such as those for AMA and ANA and they each may impart useful clinical information. In the case of antibodies to the E2 subunits, titres may reflect histological progression of PBC. In the case of antiASGPR, disappearance of the autoantibodies in patients with autoimmune hepatitis may secure a confident treatment end-point. Great progress has been made in defining the immunoserological manifestations of chronic liver disease but little has been done to distribute the resources.     

Chapter 5

No abstract available for this article.     

Cytotoxic activity of 5'-deoxy-5-fluorouridine in cultured human tumors

The cytotoxic activity of 5'-deoxy-5-fluorouridine (5'-ddFUrd) was established in six cultured human tumor lines: 47-DN and MCF-7 breast carcinomas, MG-63 osteosarcoma, HCT-8 colon carcinoma, Colo-357 pancreatic carcinoma, and HL-60 promyelocytic leukemia. Cells were exposed to a wide range of 5'-dFUrd concentrations (from 0.1 microM to 1.0 mM) for 3, 6, or 24 hrs, and then cloned using standard in vitro clonogenic assays. 5'-dFUrd exhibited its best activity in the 47-DN and MCF-7 breast cell lines and in the MG-63 osteosarcoma line (3-hr LD50 values of 32, 34, and 38 microM, respectively). Less activity was observed in the HCT-8 colon (LD50 = 195 microM) and Colo-357 pancreatic (LD50 = 155 microM) tumor lines, and ver poor activity was noted in the HL-60 leukemia cell line (LD50 = 465 microM). The metabolism of 5'-dFUrd to 5-FU (FUra) and FUra-nucleotides was determined and found to directly correlate with the potency of 5'-FUrd in these cell lines. These results suggest that: (a) there is a marked variation in sensitivity of human cancer cells of different tissue origin to 5'-dFUrd, (b) there is a direct relationship between the sensitivity of human cells to 5'-dFUrd and the ability of the cell to metabolize 5'-dFUrd to FUra, and (c) increasing exposure period of cells to 5'-dFUrd did not markedly alter 5'-dFUrd potency in all human cancer cells examined, with the exception of the 47-DN breast cancer cells.     

LRP5

Several lines of evidence have provided compelling support for low-density lipoprotein receptor-related protein 5 (LRP5) and the canonical Wnt/β-catenin signaling pathway as being important and essential for bone formation. Lrp 5 and its close homolog, Lrp6, are coreceptors with frizzled for Wnt proteins. Binding of Wnt proteins to Lrp5/6 and frizzled activates the Wnt/β-catenin signaling pathway. Mutations in Lrp5 have been shown to give rise to human diseases of low bone mass and loss of vision such as osteoporosis pseudoglioma syndrome (OPPG) and familial exudative vitreoretinopathy (FEVR) as well as several human conditions with increased bone mass and reduced fracture risk, such as the high bone mass (HBM) phenotype. Although it is well established that the Lrp5/6-Wnt canonical pathway is important in embryonic growth and development of the skeleton, its role in the adult skeleton is not clear. Accumulating evidence now supports an important role for Lrp5 in the response of the postnatal skeleton to mechanical load. Transgenic mice carrying the human HBM mutation (LRP5^G171V) have increased sensitivity to load, and mice lacking Lrp5 do not respond to mechanical load. In vivo loading of LRP5^G171V mice tibia results in increased osteoprotegerin (OPG) gene expression. Mice with either gain-or loss-of-function mutations in protein components of the canonical pathway below the level of Lrp5/6 develop high or low bone mass mainly as a consequence of altered OPG production by osteoblasts, which subsequently alters osteoclastogenesis. Thus, activation of the canonical Wnt signaling pathway apparently has multiple modes of action on bone cells to regulate bone mass. Given the clear importance of LRP5 in regulating bone mass, this gene/protein represents a potentially exciting new target for the development of anabolic agents to treat osteoporosis.     

丙型肝炎病人系列血清中5‘—NCR和C区基因变异研究

目的研究丙型肝炎病人的系列血清中HCV5′-NCR及核心区基因变化。方法4例因献血感染HCV病人的系列血标本,用特异性引物扩增5′-NCR和核心区基因并进行测序。结果所有HCV分离株基因序列均为1b和2a型，5′-NCR序列差异只与型别有关，与病人和不同时点采集的标本无关。核心区基因序列差异因病人和基因型别而异，未发现同一病人的同一基因型序列随时间而变化。结论5′-NCR序列保守性大于核心区。型别是导致基因变化的主要原因。未发现该2区段基因的核苷酸改变与时间有关。