The mutagenicities of naturally occurring xanthones were tested in Salmonella typhimurium TA100, TA98, TA97, and TA2637 by the preincubation method. Xanthydrol, gentisein, gentisin, isogentisin, 1-hydroxy-3,7-dimethoxyxanthone, 1,3,7-trimethoxyxanthone, desmethylbellidifolin, bellidifolin and dimethylbellidifolin were mutagenic, but unsubstituted xanthone was not mutagenic to TA100, TA98, TA97 and TA2637 with or without a metabolic activation system. The beta-O-glucosides, norswertianolin and swertianolin, were only mutagenic when a metabolic activation system containing beta-glucosidase was used, and the C-glucoside mangiferin was not mutagenic even with this system.

Animals↗

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Structure of thymidine kinase gene introduced into mouse Ltk- cells by a new injection method.

Pricking, a new injection method developed by Yamamoto et al. (1981), can be used to introduce DNA into cultured cells with high efficiency. Closed circular plasmid DNA containing the cloned HSV-TK gene (pTK-1) was introduced by this method and the structure of DNA in stable transformants was examined. In most clones, the introduced DNA was integrated into the mouse genome in a tandemly repeated form. The possibility of multiple integration via mouse middle repetitive sequences was also examined using the chimeric plasmid with TK genes and middle repetitive sequences (pMRTK-1). Digestion with restriction enzymes showed that the middle repetitive sequence used in this experiment had no effect on the efficiency of transformation, suggesting that this sequence is unable to mediate homologous recombination with mouse genomes.

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PubMedDate not supplied

Dual functions of insect immunity proteins in defence and development.

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Animals↗

PubMedDate not supplied

The roles of Sarcophaga defense molecules in immunity and metamorphosis.

This article summarizes recent progress (1996 1998) in our studies on self-defense molecules in Sarcophaga peregrina. A new antibacterial substance was purified and its unique structure and function revealed a novel aspect of the Sarcophaga defense system. We found a novel lectin and cysteine protease in hemocytes which will assist in the understanding of immune response of hemocytes. There have been two major advances in research on the regulation of defense gene induction: (i) cDNA cloning of a new transcriptional factor binding to the kappaB-like promoter sequence of the Sarcophaga lectin gene, (ii) methylation of cytosolic factors essential for induction of immune genes in the fatbody. Metamorphosis is an interesting event from an immunological point of view: (i) a novel protease with antibacterial activity was discovered from metamorphosing gut, and (ii) a pupal hemocyte-specific surface antigen was purified and characterized in terms of its structure and possible function for larval tissue recognition and elimination.

Animals↗

PubMedDate not supplied

Azaphilones inhibit tumor promotion by 12-O-tetradecanoylphorbol-13-acetate in two-stage carcinogenesis in mice.

Monascorubrin (an azaphilone derivative) was isolated from Monascus anka, 'Monascus pigment', a natural pigment of food additivies, was extracted from Monasucs spp., and chaetoviridin A, one of the azaphilones, was isolated from Chaetomium globosum var. flavo-viridae. Application of 1 microgram of 12-O-tetradecanoylphorbol-13-acetate (TPA), a tumor promoting agent, to the mouse ear resulted in induction of inflammation. Among monascorubrin and related compounds assayed, monascorubrin, chaetoviridin A and its related compounds inhibited the inflammatory activity of TPA in mice. The 50% inhibitory dose of these compounds for TPA-induced inflammation was 0.4-1.5 mumol. Furthermore, monascorubrin (2 mumol), chaetoviridin A (2 mumol) and Monascus pigment (1 mg) markedly suppressed the promoting effect of TPA (1 microgram) on skin tumor formation in mice initiated with 7,12-dimethylbenz[a]anthracene (50 micrograms). It is assumed that the inhibition of tumor promotion by monascorubrin, chaetoviridin A and Monascus pigment is due to anti-inflammatory activity.

9,10-Dimethyl-1,2-benzanthracene↗

PubMedDate not supplied

Thyrotropin releasing hormone (TRH)-induced release of 7B2 (neuroendocrine polypeptide) in vivo and in vitro using adenoma cells of a patient with acromegaly.

We demonstrated TRH-induced release of 7B2 (a neuroendocrine polypeptide) in vivo and in vitro (somatotroph adenoma cells) in a patient with acromegaly. The mean basal plasma 7B2 and growth hormone (GH) levels before operation were 142.8 +/- 3.2 ng/l and 52.4 +/- 1.6 micrograms/l (mean +/- SEM), respectively and these levels significantly rose after an i.v. administration of 500 micrograms of thyrotropin releasing hormone (TRH). After the transsphenoidal adenomectomy, the basal level of plasma GH was restored to the normal level and that of plasma 7B2 was slightly decreased. In addition, TRH-induced response of plasma 7B2 and GH disappeared post-operatively. In a primary culture of somatotroph adenoma cells obtained at surgery, TRH significantly induced secretions of both 7B2 and GH. Immunohistochemical studies showed the positive 7B2 and GH immunoreactivities in somatotroph adenoma cells. These findings strongly suggest that the somatotroph adenoma cells in this case produced and released 7B2 concomitant with GH.

Acromegaly↗

PubMedDate not supplied

Anti-tumor effect of N-beta-alanyl-5-S-glutathionyldihydroxyphenylalanine (5-S-GAD), a novel anti-bacterial substance from an insect.

PURPOSE: We examined the anti-tumor effect of 5-S-GAD, a novel potent inhibitor of protein tyrosine kinases, isolated from the flesh fly in order to investigate the potential use of this compound as an anti-tumor agent. METHODS: In vitro growth inhibition was evaluated using the alamarBlue assay kit. In vivo anti-tumor activity was evaluated by i.p. treatment of 5-S-GAD against xenografted melanoma (LOX-IMV1) and breast carcinoma (MDA-MB-435S) in nude mice. RESULTS: Of 38 human cancer cell lines examined, this compound showed significant cytotoxicity toward two estrogen-negative breast carcinomas (MDA-MB-231 and MDA-MB-435S) and one malignant melanoma (LOX-IMV1) in vitro, indicating that it exhibits selective cytotoxicity to certain tumor cell lines. In accordance with its in vitro anti-tumor effect, 5-S-GAD was shown to significantly repress the growth of sensitive tumor cells in nude mice. CONCLUSION: These results indicate that 5-S-GAD is potentially useful to treat certain human cancer.

Animals↗