Electron-hole symmetry and magnetic coupling in antiferromagnetic LaFeAsO

When either electron or hole doped at concentrations x approximately 0.1, the LaFeAsO family displays remarkably high temperature superconductivity with Tc up to 55 K. In the most energetically stable Q-->M=(pi,pi,0) antiferromagnetic (AFM) phase comprised of tetragonal-symmetry breaking alternating chains of aligned spins, there is a deep pseudogap in the Fe 3d states centered at the Fermi energy arising from light carriers (m* approximately 0.25-0.33), and very strong magnetophonon coupling is uncovered. Doping (of either sign) beyond x approximately 0.08 results in heavy carriers per Fe (by roughly an order of magnitude) with a large Fermi surface. Calculated Fe-Fe transverse exchange couplings Jij(R) reveal that exchange coupling is strongly dependent on both the AFM symmetry and on the Fe-As distance.

Phase II trial of irinotecan plus oxaliplatin and 5-fluorouracil/leucovorin in patients with untreated metastatic gastric adenocarcinoma

BACKGROUND

This nonrandomized open label phase II study evaluated the efficacy and safety of FOLFOXIRI in metastatic or recurrent gastric cancer patients.

PATIENTS AND METHODS

Patients with histologically proven, metastatic gastric adenocarcinoma, aged 18-70 years, performance status zero to two, no prior chemotherapy, and with signed written informed consent were eligible. Treatment consisted of irinotecan 150 mg/m2 day 1, oxaliplatin 85 mg/m2 day 1, leucovorin 100 mg/m2 day 1, and 5-fluorouracil 2000 mg/m2 as a 48-h continuous infusion starting on day 1, which was repeated every 2 weeks.

RESULTS

From August 2004 to August 2005, 48 patients were prospectively enrolled. The median age was 54 years (24-69). In total, 386 cycles were administered with a median of nine cycles per patient (range 1-12 cycles) and 45 of 48 patients were assessable for treatment response. An independent review of tumor responses resulted in overall response rate of 66.7% (95% confidence interval=53.4% to 80.0%) by intent-to-treat analysis with one complete response and 31 partial responses. The median survival of all patients was 14.8 months and the median time to progression was 9.6 months. Most common grade 3/4 toxic effects were neutropenia (12% of all cycles) and emesis (8% of all cycles). Grade 2 peripheral neuropathy occurred in five patients. One (2%) patient had severe tumor bleeding and five (10%) patients experienced grade 3 diarrhea.

CONCLUSIONS

The modified FOLFOXIRI combination chemotherapy showed a very promising preliminary antitumor activity and was generally well tolerated as a first-line treatment of patients with metastatic gastric cancer.

In vitro anti-Helicobacter pylori activity of panaxytriol isolated from ginseng

This study investigated the effect that some polyacetylenes and protopanaxatriol, which were isolated from heated ginseng (family Araliaceae), have on inhibiting Helicobacter pylori (HP) growth. Among the compounds tested, panaxytriol was quite effective in inhibiting HP growth with an MIC of 50 microg/ml. Ginsenoside Rh1 and protopanaxatriol weakly inhibited H+/K+-ATPase from a rat stomach.

Effects of reactive oxygen species on proliferation of Chinese hamster lung fibroblast (V79) cells

Reactive oxygen species (ROS) have emerged as important signaling molecules in the regulation of various cellular processes. In our study, we investigated the effect of a wide range of ROS on Chinese hamster lung fibroblast (V79) cell proliferation. Treatment with H2O2 (100 microM), superoxide anion (generated by 1 mM xanthine and 1 mU/ml xanthine oxidase), menadione, and phenazine methosulfate increased the cell proliferation by approximately 50%. Moreover, a similar result was observed after partial inhibition of superoxide dismutase (SOD) and glutathione peroxidase. This upregulation of cell proliferation was suppressed by pretreatment with hydroxyl radical scavengers and iron chelating agents. In addition to ROS, treatment with exogenous catalase and SOD mimic (MnTMPyP) suppressed the normal cell proliferation. Short-term exposure of the cells to 100 microM H2O2 was sufficient to induce proliferation, which indicated that activation of the signaling pathway is important as an early event. Accordingly, we assessed the ability of H2O2 to activate mitogen-activated protein kinases (MAPK). Jun-N-terminal kinase (JNK) and p38 MAPK were both rapidly and transiently activated by 100 microM H2O2, with maximal activation 30 min after treatment. However, the activity of extracellular signal-regulated kinase (ERK) was not changed. Pretreatment with SB203580 and SB202190, specific inhibitors of p38 MAPK, reduced the cell proliferation induced by H2O2. The activation of both JNK and p38 MAPK was also suppressed by pretreatment with hydroxyl radical scavenger and iron chelating agents. Our results suggest that the trace metal-driven Fenton reaction is a central mechanism that underlies cell proliferation and MAPK activation.

Cell biology of limb patterning

Of vertebrate organ systems, the developing limb has been especially well characterized. Morphological studies have yielded a wealth of information describing limb outgrowth and have allowed for the identification of a multitude of important factors. In terms of the latter, key signaling pathways are known to control numerous aspects of limb development, including establishment of the early limb field, determination of limb identity, elongation of the limb bud, specification of digit pattern, and sculpting of the digits. Modification of underlying signaling pathways can thus result in dramatic alterations of the limb phenotype, accounting for many of the diverse limb patterns observed in nature. Given this, it is clear that signaling pathways regulate the highly orchestrated and tightly controlled sequence of cellular events necessary for limb outgrowth; however, exactly how molecular signals interface with the cell biology of limb development remains largely a mystery. In this review we first provide an overview of a number of the morphogenetic signaling pathways that have been identified in the developing limb and then review how a subset of these signals are known to modify cell behaviors important for limb outgrowth.

In vitro anti-Helicobacter pylori activity of irisolidone isolated from the flowers and rhizomes of Pueraria thunbergiana

The inhibitory effect of isoflavones isolated from the flowers and rhizomes of Pueraria thunbergiana (Leguminosae) on the growth of Helicobacter pylori (HP) was investigated. Isoflavone glycosides did not inhibit the growth of HP. However, their aglycones, irisolidone, tectorigenin and genistein, inhibited HP growth. Among them, irisolidone had the most potent inhibitory activity against HP and its MIC was 12.5-25 micrograms/ml. Genistein only weakly inhibited the urease of HP and H+/K(+)-ATPase of rat stomach: its IC50 were 0.43 and 0.89 mg/ml, respectively.

Proteome analysis of metabolically engineered Escherichia coli producing Poly(3-hydroxybutyrate)

Recombinant Escherichia coli strains harboring heterologous polyhydroxyalkanoate (PHA) biosynthesis genes were shown to accumulate unusually large amounts of PHA. In the present study, integrated cellular responses of metabolically engineered E. coli to the accumulation of poly(3-hydroxybutyrate) (PHB) in the early stationary phase were analyzed at the protein level by two-dimensional gel electrophoresis. Out of 20 proteins showing altered expression levels with the accumulation of PHB, 13 proteins were identified with the aid of mass spectrometry. Three heat shock proteins, GroEL, GroES, and DnaK, were significantly up-regulated in PHB-accumulating cells. Proteins which play essential roles in protein biosynthesis were unfavorably influenced by the accumulation of PHB. Cellular demand for the large amount of acetyl coenzyme A and NADPH for the PHB biosynthesis resulted in the increased synthesis of two enzymes of the glycolytic pathway and one enzyme of the Entner-Doudoroff pathway. The expression of the yfiD gene encoding a 14.3-kDa protein, which is known to be produced at low pH, was greatly induced with the accumulation of PHB. Therefore, it could be concluded that the accumulation of PHB in E. coli acted as a stress on the cells, which reduced the cells' ability to synthesize proteins and induced the expression of various protective proteins.

Expression patterns of Fgf-8 during development and limb regeneration of the axolotl

Fgf-8 is one of the key signaling molecules implicated in the initiation, outgrowth, and patterning of vertebrate limbs. However, it is not clear whether FGF-8 plays similar role in development and regeneration of urodele limbs. We isolated a Fgf-8 cDNA from the Mexican axolotl (Ambystoma mexicanum) through the screening of an embryo cDNA library. The cloned 1.26-kb cDNA contained an open reading frame encoding 212 amino acid residues with 84%, 86%, and 80% amino acid identities to those of Xenopus, chick, and mouse, respectively. By using the above clone as a probe, we examined the temporal and spatial expression patterns of Fgf-8 in developing embryos and in regenerating larval limbs. In developing embryos, Fgf-8 was expressed in the neural fold, midbrain-hindbrain junction, tail and limb buds, pharyngeal clefts, and primordia of maxilla and mandible. In the developing axolotl limb, Fgf-8 began to be expressed in the prospective forelimb region at pre-limb-bud and limb bud stages. Interestingly, strong expression was detected in the mesenchymal tissue of the limb bud before digit forming stages. In the regenerating limb, Fgf-8 expression was noted in the basal layer of the apical epithelial cap (AEC) and the underlying thin layer of mesenchymal tissue during blastema formation stages. These data suggest that Fgf-8 is involved in the organogenesis of various craniofacial structures, the initiation and outgrowth of limb development, and the blastema formation and outgrowth of regenerating limbs. In the developing limb of axolotl, unlike in Xenopus or in amniotes such as chick and mouse, the Fgf-8 expression domain was localized mainly in the mesenchyme rather than epidermis. The unique expression pattern of Fgf-8 in axolotl suggests that the regulatory mechanism of Fgf-8 expression is different between urodeles and other higher species. The expression of Fgf-8 in the deep layer of the AEC and the thin layer of underlying mesenchymal tissue in the regenerating limbs support the previous notion that the amphibian AEC is a functional equivalent of the AER in amniotes.

Antitumor activity of Bifidobacterium spp. isolated from a healthy Korean

The antitumor activity of Bifidobacterium breve K-110, and K-111, and B. infantis K-525 was investigated. These Bifidobacterial cells and their cell wall preparations (WPG) significantly increased the survival rate of mice who had been intraperitoneally implanted with sarcoma 180 cells. Solid tumor growth was inhibited even when the sarcoma 180 cells were implanted into the groins of the mice. However, the Bifidobacterial cells did not show in vitro cytotoxicity against tumor cell lines. Cell kinetic studies revealed that these WPGs induced neutrophils, which were followed by macrophages, at the site of peritoneal injection. The WPGs directly activated these cells to inhibit the growth of tumor cells in in vitro assays. Our results suggest that Bifidobacterial WPGs induce and activate nonspecific phagocytes in situ to reject growing tumor cells in the mouse peritoneal cavity.

In vitro inhibitory effect of some flavonoids on rotavirus infectivity

The inhibitory effects of some flavonoids on the infectivity of rotavirus, which predominantly causes sporadic diarrhea in infants and young children, were investigated. Among tested flavonoids, diosmin and hesperidin had the most potent inhibitory activity on rotavirus infection. The fifty percent inhibitory concentration of both compounds was 10 microM. However, their aglycones did not have the inhibitory activity. The rutinose moiety of flavonoids should protect against the invasion of rotavirus into cells.

Metabolism of rhaponticin and chrysophanol 8-o-beta-D-glucopyranoside from the rhizome of rheum undulatum by human intestinal bacteria and their anti-allergic actions

Rhaponticin and chrysophanol 8-o-beta-D-glucopyranoside isolated from the rhizomes of Rheum undulatum (Family Polygonaceae) are metabolized to rhapontigenin and chrysophanol, respectively, by human intestinal microflora. Most intestinal bacteria isolated from human feces catalyzed these metabolic pathways. Among rhaponticin and chrysophanol 8-o-beta-D-glucopyranoside and their metabolites, rhapontigenin had the most potent inhibitory activity on a hyaluronidase, a histamine release from mast cell and passive cutaneous anaphylaxis (PCA) PCA reaction. The inhibitory activity of rhapontigenin was more potent than that of disodium cromoglycate, one of the commercial anti-allergic drugs. These results suggest that rhaponticin in the rhizomes of R. undulatum is a prodrug that has an extensive anti-allergic property.

T-DNA insertional mutagenesis for functional genomics in rice

We have produced 22 090 primary transgenic rice plants that carry a T-DNA insertion, which has resulted in 18 358 fertile lines. Genomic DNA gel-blot and PCR analyses have shown that approximately 65% of the population contains more than one copy of the inserted T-DNA. Hygromycin resistance tests revealed that transgenic plants contain an average of 1.4 loci of T-DNA inserts. Therefore, it can be estimated that approximately 25 700 taggings have been generated. The binary vector used in the insertion contained the promoterless beta-glucuronidase (GUS) reporter gene with an intron and multiple splicing donors and acceptors immediately next to the right border. Therefore, this gene trap vector is able to detect a gene fusion between GUS and an endogenous gene, which is tagged by T-DNA. Histochemical GUS assays were carried out in the leaves and roots from 5353 lines, mature flowers from 7026 lines, and developing seeds from 1948 lines. The data revealed that 1.6-2.1% of tested organs were GUS-positive in the tested organs, and that their GUS expression patterns were organ- or tissue-specific or ubiquitous in all parts of the plant. The large population of T-DNA-tagged lines will be useful for identifying insertional mutants in various genes and for discovering new genes in rice.

Biotransformation of glycyrrhizin by human intestinal bacteria and its relation to biological activities

The relationship between the metabolites of glycyrrhizin (18beta-glycyrrhetinic acid-3-O-beta-D-glucuronopyranosyl-(1-->2)-beta-D-glucuronide, GL) and their biological activities was investigated. By human intestinal microflora, GL was metabolized to 18beta-glycyrrhetinic acid (GA) as a main product and to 18beta-glycyrrhetinic acid-3-O-beta-D-glucuronide (GAMG) as a minor product. The former reaction was catalyzed by Eubacterium L-8 and the latter was by Streptococcus LJ-22. Among GL and its metabolites, GA and GAMG had more potent in vitro anti-platelet aggregation activity than GL. GA also showed the most potent cytotoxicity against tumor cell lines and the potent inhibitory activity on rotavirus infection as well as growth of Helicobacter pylori. GAMG, the minor metabolite of GL, was the sweetest.

Inhibitory effect of herbal medicines on rotavirus infectivity

The inhibitory effect of some traditional herbal medicines on the infectivity of rotavirus, which predominantly occurs in sporadic diarrhea in infants and young children, was investigated. Among the 34 kinds of herbal medicines tested, the fruit of Citrus aurantium had the most potent inhibitory activity on rotavirus infection. The active components of the fruit of Citrus aurantium were neohesperidin and hesperidin. Their 50% inhibitory concentrations were 25 and 10 microM, respectively.

5-(beta-Cyclodextrinylamino)-5-Deoxy-alpha-D-Riboses as Models for Nuclease, Ligase, Phosphatase, and Phosphorylase

beta-Cyclodextrin derivatives crowned with ribose rings (such as 1) catalyzed the hydrolysis, esterification, and phosphorylation of catechol-derived phosphate esters. The vicinal cis-diols on the ribose groups appear to play a major role in the catalytic activity of these enzyme models by the formation of hydrogen bonds which activate the phosphorus atom to nucleophilic attack.

Metabolism of 6"-O-xylosyltectoridin and tectoridin by human intestinal bacteria and their hypoglycemic and in vitro cytotoxic activities

6"-O-Xylosyltectoridin and tectoridin isolated from the flowers of Pueraria thunbergiana (Leguminosae), are metabolized to tectorigenin by human intestinal bacteria. Although tectoridin is metabolized to tectorigenin by most intestinal bacteria, 6"-O-xylosyltectoridin is metabolized to tectorigenin via tectoridin by only a few intestinal bacteria, such as Bifidobacterium breve K-110 and Eubacterium A-44. The metabolite, tectorigenin, had more potent hypoglycemic activity as well as in vitro cytotoxic activity against tumor cell lines than 6"-O-xylosyltectoridin and tectoridin. These results suggest that 6"-O-xylosyltectoridin and tectoridin are prodrugs which can be transformed to the active agents by human intestinal bacteria.

Metabolism of quercitrin by human intestinal bacteria and its relation to some biological activities

When quercitrin was anaerobically incubated with human intestinal bacteria, quercetin, 3,4-dihydroxyphenylacetic acid and 4-hydroxybenzoic acid were found as metabolites. The main metabolite was quercetin. The bacterium transforming quercitrin to quercetin was Fusobacterium K-60. However, Bacteroides JY-6, which produced alpha-L-rhamnosidase, did not transform quercitrin to quercetin. Among quercitrin and its metabolites, 3,4-dihydroxyphenylacetic acid and 4-hydroxylphenylacetic acid had more potent activity than quercitrin on in vitro anti-platelet aggregation activity, and quercetin and 3,4-dihydroxyphenylacetic acid showed more potent cytotoxicity against tumor cell lines than quercitrin and 4-hydroxylphenylacetic acid.

In vitro anti-Helicobacter pylori activity of some flavonoids and their metabolites

The inhibitory effect of flavonoids and phenolic acids, which could be transformed from flavonoids by human intestinal microflora, on the growth of Helicobacter pylori (HP) was investigated. Ponciretin, hesperetin, naringenin and diosmetin were active against HP. Among them, ponciretin was the most potent and its MIC was 10-20 micrograms/ml. However, these active compounds against HP did nearly not inhibit the urease activity of HP.

Anti-Helicobacter pylori activity of the metabolites of poncirin from Poncirus trifoliata by human intestinal bacteria

Poncirin was isolated from water extract of the fruits of Poncirus trifoliata and metabolized by human intestinal bacteria. The inhibitory effect of poncirin and its metabolites by these bacteria on the growth of Helicobacter pylori (HP) was investigated. Among them, ponciretin (5,7-dihydroxy-4'-methoxyflavanone), the main metabolite most potently inhibited the growth of HP, with a minimum inhibitory concentration (MIC) of 10-20 microg/ml. However, poncirin and its metabolites except ponciretin did not inhibit the growth of HP, nor did they inhibit HP urease.

Dose assessment and behavior of tritium in environmental samples around Wolsong nuclear power plant

For the estimation of the dispersion trend of tritium discharged from the Wolsung nuclear power plant, the present level of tritium in environmental samples in the vicinity of the Wolsong site has been studied. On the basis of tritium concentrations in environmental samples, the effective dose due to tritium has been estimated for an individual and population within a 16 km radius from the Wolsong site. The annual effective dose of tritium to an inhabitant around the Wolsong site ranged from 0.15 microSv y-1 to 1.3 microSv y-1. The dose level was negligible and much lower than some applicable standards, i.e. the limit on exposure from nuclear fuel cycle to the general public as recommended by ICRP (1 mSv y-1) or US EPA's limit (0.25 mSv y-1). The collective dose to the total population within a 16 km radius from the site, 1.2 x 10(-2) man.Sv y-1 was much lower than 1 man.Sv y-1, an applicable criterion for the so-called "exemption" of radiation sources and practices from regulatory control.

Biotransformation of glycyrrhizin to 18beta-glycyrrhetinic acid-3-O-beta-D-glucuronide by Streptococcus LJ-22, a human intestinal bacterium

By human intestinal bacteria, glycyrrhizin (18beta-glycyrrhetinic acid-3-O-[beta-D-glucuronopyranosyl-(1-->2)-betaD-glucuro nopyranoside], GL) was metabolized to 18beta-glycyrrhetinic acid (GA): the main pathway metabolized GL to GA by glucuronidases of Bacteroides J-37 and Eubacterium sp. GLH and the minor pathway metabolized GL to 18beta-glycyrrhetinic acid-3-O-beta-D-glucuronide (GAMG) by beta-glucuronidase of Streptococcus LJ-22. Beta-Glucuronidase from Streptococcus LJ-22 hydrolyzed GL to GAMG (not GA). The molecular weight and optimal pH of the enzyme were 240 kDa and 5-6.

Metabolism of liriodendrin and syringin by human intestinal bacteria and their relation to in vitro cytotoxicity

When liriodendrin or syringin was incubated for 24 h with human intestinal bacteria, two metabolites, (+)-syringaresinol-beta-D-glucopyranoside and (+)-syringaresinol, from liriodendrin and one metabolite, synapyl alcohol, from syringin were produced. The metabolic time course of liriodendrin was as follows: at early time, liriodendrin was converted to (+)-syringaresinol-beta-D-glucopyranoside, and then (+)-syringaresinol. The in vitro cytotoxicities of these metabolites, (+)-syringaresinol and synapyl alcohol, were superior to those of liriodendrin and syringin.

Degradation of acharan sulfate and heparin by Bacteroides stercoris HJ-15, a human intestinal bacterium

When glycosaminoglycan (GAG)-degrading enzymes were measured in normal human stool suspensions, all 5 tested different stools degraded titrable heparin and acharan sulfate. GAG-degrading bacteria were screened from the isolates of human stools. Among them, HJ-15 had the most potent activities of heparinases (GAGs-degrading enzymes). However, HJ-15 produced the enzyme even if in the media without heparin. Acharan sulfate lyase was induced by acharan sulfate and heparin. Heparinase production was also induced by these GAGs. These enzymes, acharan sulfate lyase and heparinase, were produced in exponential and stationary phase of HJ-15 growth, respectively. Optimal pHs of the acharan sulfate lyase and heparinase activities were 7.2 and 7.5, respectively. The biochemical properties of HJ-15 was similar to those of B. stercoris. However, difference from B. stercoris was utilization of raffinose. This HJ-15 also degraded chondroitin sulfates A and C.

Anti-Helicobacter pylori activity of herbal medicines

The extracts of Coptidis japonica (rhizoma), Eugenia caryophyllata (flower), Rheum palmatum (rhizoma), Magnolia officinalis (cortex) and Rhusjavanica (galla rhois) potently inhibited the growth of Helicobacter pylori (HP). However, these herbal extracts showed no inhibitory effect on HP urease except Galla rhois. Among the components separated from active herbal extracts by silica gel column chromatography, the inhibitory effects of decursinol angelate and decursin on the growth of HP were the most potent, followed by magnolol, berberine, cinnamic acid, decursinol and gallic acid. Minimum inhibitory concentrations (MICs) of decursin and decursinol angelate were 6-20 microg/ml.

Metabolism of puerarin and daidzin by human intestinal bacteria and their relation to in vitro cytotoxicity

When puerarin or daidzin were incubated for 24 h with human intestinal bacteria, two metabolites, daidzein and calycosin, were produced from them, respectively. The metabolic time course of puerarin was as follows: at an early time, puerarin was converted to daidzin, and then calycosin. The metabolic time course of daidzin by human intestinal bacteria was also similar to that of puerarin. The in vitro cytotoxicities of these metabolites, calycosin and daidzein, were superior to those of puerarin and daidzein.