Bacopaside I and II: two pseudojujubogenin glycosides from Bacopa monniera

Two saponins, designated as bacopaside I and II, have been isolated from Bacopa monniera Wettst. and their structures have been elucidated as 3-O-alpha-L-arabinofuranosyl-(1-->2)-[6-O-sulphonyl-beta-D-glucopyranosyl-(1-->3)]-alpha-L-arabinopyranosyl pseudojujubogenin (1) and 3-O-alpha-L-arabinofuranosyl-(1-->2)-[beta-D-glucopyranosyl (1-->3)]-beta-D-glucopyranosyl pseudojujubogenin (2) mainly on the basis of 2D NMR and other spectral analyses.     

Isolation of a new potent cytotoxic pigment along with indigotin from the pathogenic basidiomycetous fungus Schizophyllum commune

An indole derivative, schizocommunin, was isolated along with indigotin (indigo), indirubin, isatin, and tryptanthrin, from the liquid culture medium in which a culture of Schizophyllum commune, isolated from the bronchus of a human patient with allergic bronchopulmonary mycosis, had been grown. The structure of schizocommunin was established by spectroscopic investigation. Schizocommunin showed the strong cytotoxicity against murine lymphoma cells. The assignments of the ¹H- and ¹³C-NMR signals of indigotin were also listed. This revised version was published online in June 2006 with corrections to the Cover Date.     

Intracellularly inducible, ubiquitin hydrolase-insensitive tandem ubiquitins inhibit the 26S proteasome activity and cell division

We constructed polyubiquitin derivatives that contain a tandem repeat of ubiquitins and were insensitive to ubiquitin hydrolases. They were designated tandem ubiquitin (tUb) with the number of repeats, such as tUb2. When tUbs were expressed under the control of the GAL1 promoter in the wild-type yeast strain, growth was strongly inhibited. Under these conditions, the degradation of N-end rule substrates, a UFD substrate and Gcn4 was inhibited, indicating that the tUb inhibits 26S proteasome activity. Consistent with this, tUb binds to the 26S proteasome. We showed that tUb inhibited the in vitro degradation of polyubiquitinylated Sic1 by the 26S proteasome. When tUB6 messenger RNA was injected into Xenopus embryos, cell division was inhibited, suggesting that tUb can be used as a versatile inhibitor of the 26S proteasome.     

Synthesis and pharmacological properties of benzamide derivatives as selective serotonin 4 receptor agonists

A series of 4-amino-5-chloro-2-methoxy-N-(piperidin-4-ylmethyl)benzamides with a polar substituent group at the 1-position of the piperidine ring was synthesized and evaluated for its effect on gastrointestinal motility. The benzoyl, phenylsulfonyl, and benzylsulfonyl derivatives accelerated gastric emptying and increased the frequency of defecation. One of them, 4-amino-N-[1-[3-(benzylsulfonyl)propyl]piperidin-4-ylmethyl]-5-chloro-2-methoxybenzamide (13a, Y-36912), was a selective 5-HT4 receptor agonist offering potential as a novel prokinetic with reduced side effects derived from 5-HT3- and dopamine D2 receptor-binding affinity. In the oral route of administration, this compound enhanced gastric emptying and defecation in mice, and has a possibility as a prokinetic agent, which is effective on both the upper and the lower gastrointestinal tract.     

Hepatocyte growth factor enhances adhesion of breast cancer cells to endothelial cells in vitro through up-regulation of CD44

For cancer metastasis, tumor cells present in the circulation must first adhere to the endothelium. Integrins play a central role in leukocyte adhesion to the endothelium and subsequent migration into tissues. The majority of tumor cells derived from solid cancers, including breast cancer, do not express integrins. We investigated the mechanisms of adhesion and transendothelial migration of cancer cells using breast carcinoma cell lines. Our results showed the following features of breast cancer cells: (1) HGF stimulated breast cancer cells by up-regulating CD44 expression in a concentration-dependent manner. (2) the maximum level of HGF-induced CD44 up-regulation on breast cancer cell lines occurred within 3 h. (3) HGF-induced up-regulation of CD44 was mediated by the tyrosine kinase signaling pathway. (4) HGF induced CD44-mediated adhesion of tumor cell lines to bone marrow-derived endothelial cells. (5) HGF did not change rolling of breast cancer cell lines on bone marrow-derived endothelial cells, but enhanced firm adhesion of cancer cells on endothelial cells under shear stress conditions. (6) HGF increased transendothelial migration of cancer cells. Our results indicate that HGF stimulates CD44-mediated adhesion of breast cancer cells to bone marrow-derived endothelial cells, which subsequently results in transendothelial migration of tumor cells. These results suggest that CD44 may confer the metastatic properties of breast cancer cells and, therefore, could be used as a target in future molecular cancer therapy.     

Molecular heterogeneity of heat-stable toxin-producing and non-producing Escherichia coli O25 strains isolated in Japan

Escherichia coli O25 strains that produce heat-stable toxin (ST) have been recently isolated in Japan, and epidemiological study of this type of enterotoxigenic E. coli is required. In this study the heterogeneity of 16 ST-producing and non-producing strains of E. coli O25 was investigated. All eight ST-producing strains were shown to have STIb gene, and seven of them had similar profiles of plasmids, ladder-banding of LPS in SDS-polyacrylamide gel electrophoresis, and chromosomal DNA digestions in pulsed-field gel electrophoresis (PFGE). In contrast, ST-non-producing strains were more heterogeneous in all parameters examined. PFGE of the digested chromosomal DNA with several restriction enzymes was proved to be an effective procedure to compare the closely related strains of E. coli O25.     

Occurrence of an alpha-galacturonosyl-ceramide in the dioxin-degrading bacterium Sphingomonas wittichii

The chemical structure of two glycosphingolipids (GSLs) found in the dioxin-degrading bacterium Sphingomonas wittichii strain RW1 was investigated by means of mass spectrometry and (1)H-nuclear magnetic resonance spectroscopy. One of the GSLs was alpha-D-glucuronosyl-ceramide, commonly present in Sphingomonas spp., and the other was proved to be alpha-D-galacturonosyl-ceramide, whose sugar configuration has not been reported before. In both GSLs the ceramide portion was composed of myristic acid or 2-hydroxy-myristic acid as the fatty acid, and 2-amino-1,3-octadecanediol or 2-amino-cis-13,14-methylene-1,3-eicosanediol as the dihydrosphingosine.     

Association of a regulatory gene, slyA with a mouse virulence of Salmonella serovar Choleraesuis

The influence of slyA gene, originally found in Salmonella serovar Typhimurium as a regulatory gene for the expression of virulence genes, on a mouse virulence of S. serovar Choleraesuis was investigated by using an slyA-defective mutant. The defective mutant was constructed by the insertion of a kanamycin-resistance gene (aph) into the cloned slyA gene, and the homologous recombination with the intact slyA gene on the chromosome. The mutant strain showed the LD50 value for BALB/c mouse approximately 10(5) higher than that of the parent strain. The increase of the LD50 value was the same order as that shown by the mutation of the slyA gene of S. serovar Typhimurium, although LD50 of the wild-type strain of S. serovar Choleraesuis was 40-fold higher than that of S. serovar Typhimurium. The time course of infection observed in the mice organs also proved the clear difference of the virulence between the parent and the mutant strains. These results suggested that the slyA gene product functions as a virulence-associated regulator also in S. serovar Choleraesuis.     

Regeneration of hippocampal pyramidal neurons after ischemic brain injury by recruitment of endogenous neural progenitors

The adult brain is extremely vulnerable to various insults. The recent discovery of neural progenitors in adult mammals, however, raises the possibility of repairing damaged tissue by recruiting their latent regenerative potential. Here we show that activation of endogenous progenitors leads to massive regeneration of hippocampal pyramidal neurons after ischemic brain injury. Endogenous progenitors proliferate in response to ischemia and subsequently migrate into the hippocampus to regenerate new neurons. Intraventricular infusion of growth factors markedly augments these responses, thereby increasing the number of newborn neurons. Our studies suggest that regenerated neurons are integrated into the existing brain circuitry and contribute to ameliorating neurological deficits. These results expand the possibility of novel neuronal cell regeneration therapies for stroke and other neurological diseases.