杜仲叶林枝木醋液化学成分及抑菌活性研究

以杜仲叶林枝木为原料,采用干馏法,分90℃~200℃、200℃~340℃和340℃~520℃共3个温度段收集杜仲叶林枝木粗木醋液,经过静置、活性炭粉吸附焦油处理等过程得到精制木醋液,然后对所得木醋液的理化性质和抑菌活性进行了研究,并对抑菌活性最强的木醋液的化学成分进行了GC/MS分析。结果表明:(1)杜仲叶林枝木醋液产生的温度范围为90℃~520℃,其中200℃~340℃段产量最大、pH值最低、有机酸含量最高、抑菌能力也最强。(2)GC/MS分析表明,温度段为200℃~340℃的木醋液中约含有42种化合物,主要为酚类、酸类、酮类和醛类等,其中酚类化合物含量最高,占总量的46.81%,其次为有机酸类物质。初步分析确定木醋液抑菌活性成分为酚类物质。     

Different immunodominance of HIV-1-specific CTL epitopes among three subtypes of HLA-A*26 associated with slow progression to AIDS

It is speculated that HLA-A^∗26-restricted HIV-1-specific CTLs can control HIV-1, since HLA-A^∗26 is associated with a slow progression to AIDS. In three major HLA-A^∗26 subtypes, HLA-A^∗2601-restricted, and HLA-A^∗2603-restricted HIV-1 epitopes have been identified, but HLA-A^∗2602-restricted ones have not. We here identified HLA-A^∗2602-restricted HIV-1 epitopes by using reverse immunogenetics and compared the immunodominance of the epitopes among the three subtypes. Out of 110 HIV-1 peptides carrying HLA-A^∗26 anchor residues, only the Gag169-177 peptide, which had been previously identified as an HLA-A^∗2601- and HLA-A^∗2603-restricted immunodominant epitope, induced Gag169-177-specific CD8⁺ T cells from only two of six HLA-A^∗2602⁺ HIV-1-infected individuals. No difference in affinity of this epitope peptide was found among these three HLA-A^∗26 subtypes, indicating that Gag169-177 was effectively presented by HLA-A^∗2602 but recognized as a subdominant epitope in HIV-1-infected HLA-A^∗2602⁺ individuals. These findings indicate different immunodominance of Gag169-177 epitope among 3 HLA-A^∗26 subtypes.     

Split conformation of Chaetomium thermophilum Hsp104 disaggregase

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Biosynthetic studies on chlorinated indoles in Vicia faba

We identified L-4-chlorotriptophan (L-4-Cl-Trp) in two week old plants of Vicia faba. Deuterium labeled indole was incorporated to 4-chloroindole in these plants. Deuterium labeled L- and D-4-Cl-Trp were both synthesized and, when supplied to the plants only L-4-Cl-Trp was incorporated to 4-Cl-indoleacetic acid, although the incorporation ratio was very low.     

Commensal Bacteria-Dependent Indole Production Enhances Epithelial Barrier Function in the Colon

Microbiota have been shown to have a great influence on functions of intestinal epithelial cells (ECs). The role of indole as a quorum-sensing (QS) molecule mediating intercellular signals in bacteria has been well appreciated. However, it remains unknown whether indole has beneficial effects on maintaining intestinal barriers in vivo. In this study, we analyzed the effect of indole on ECs using a germ free (GF) mouse model. GF mice showed decreased expression of junctional complex molecules in colonic ECs. The feces of specific pathogen-free (SPF) mice contained a high amount of indole; however the amount was significantly decreased in the feces of GF mice by 27-fold. Oral administration of indole-containing capsules resulted in increased expression of both tight junction (TJ)- and adherens junction (AJ)-associated molecules in colonic ECs in GF mice. In accordance with the increased expression of these junctional complex molecules, GF mice given indole-containing capsules showed higher resistance to dextran sodium sulfate (DSS)-induced colitis. A similar protective effect of indole on DSS-induced epithelial damage was also observed in mice bred in SPF conditions. These findings highlight the beneficial role of indole in establishing an epithelial barrier in vivo.     

Up-regulation of vascular endothelial growth factor in response to glucose deprivation

Vascular endothelial growth factor (VEGF), also known as a vascular permeability factor (VPF), is an endothelial specific mitogen and is a potent inducer of angiogenesis. Recently it has been reported that hypoxia induces VEGF mRNA expression in various cells. Since both oxygen and glucose are required for efficient production of energy, we examined the effect of glucose deprivation on VEGF mRNA expression and VEGF protein production in U-937 (a human monocytic cell line) cells. Both the mRNA expression and secretion of VEGF increased after exposure to low glucose. Addition of L-glucose, the L-stereoisomer of D-glucose, did not prevent the up-regulation of VEGF expression. The conditioned medium from glucose-deprived cells, followed by supplementation with glucose, did not up-regulate VEGF mRNA expression in U-937 cells. The low glucose-induced VEGF mRNA expression returned to the control level after supplementation with D-glucose. Furthermore, oligomycin, a mitochondrial ATP synthase inhibitor, increased VEGF protein production. The results suggest that the up-regulation of VEGF mRNA in U-937 cells in response to glucose deprivation is not mediated by autocrine factors from the cells nor is the osmotic change of the medium mediated by the deficiency of glucose metabolism in the cells. Our results also suggest that the intracellular ATP depletion due to glucose deprivation may be one of the causes for increased VEGF mRNA expression. We speculate that local hypoglycemia may act as an essential trigger for angiogenesis through the VEGF gene expression.     

Establishment and characterization of a new human renal cell carcinoma cell line (KRC/Y)

Summary A new renal cell carcinoma (RCC) cell line (KRC/Y) has been established from a surgical specimen of a 41-yr-old Japanese female patient with RCC composed of both clear cells and granular cells. This cell line has been maintained for more than 15 mo. through 45 passages with a stable growth, KRC/Y cells have clear or eosinophilic polygonal cytoplasm and round to oval nuclei with one or two nucleoli, and proliferate in a pavementlike cell arrangement with a lack of contanct inhibition. By electron microscopy, these cells contain abundant fat droplets and glycogen granules or well-developed organells or both, which were also observed in the original tumor. The doubling time of these cells at the 15th passage was 73 h. The chromosome number was from 37 to 45 with a hypodiploid modal number of 42. Tumorigenicity was identified by tumor formation after subcutaneous injections of KRC/Y cells in nude mice, which showed close resemblance to the original tumor by light and electron microscope observations. This study was supported in part by Sarah Cousin Fund, Boston, MA.