A case of acute gastric mucosal lesions associated with Helicobacter heilmannii infection

A 69-year-old-woman presented with acute epigastric pain, nausea, vomiting and heartburn. Endoscopy disclosed acute gastric mucosal lesions including mucosal edema, erosions, and ulcers with blood crusts in the antrum. Touch cytology and histological assessment obtained from the affected mucosa revealed acute neutrophilic gastritis and single longer and more coiled organisms than Helicobacter pylori, suggesting Helicobacter heilmannii. Electron micropragh confirmed the characteristic morphology. Despite a positive rapid urease test, H. pylori was not isolated by culture or detected by histology and Gram smears. Based on these findings, a diagnosis of acute gastric mucosal lesions associated with H. heilmannii infection was established. This was successfully treated with a 2-week triple therapy consisting of lansoprazole, clarithromycin and metronidazole with persistent endoscopic and histological remission. This is a rare case of H. heilmannii-associated acute gastric mucosal lesions, diagnosed by morphology using touch cytology and histology. The patient might benefit from antimicrobial treatment employing the regimen effective for H. pylori.     

Over-expression of ζ glutathione S-transferase in transgenic rice enhances germination and growth at low temperature

To develop a rice cultivar that would be suitable for direct-seedingcultivation in cooler temperate regions, we generated transgenic rice plants inwhich a rice encoding a -class glutathioneS-transferase (GST) under the control of a maize ubiquitinpromoter. GSTs have been suggested to be responsible for tolerance to variousstresses such as cold, salt and drought by detoxification of xenobioticcompounds and reactive oxygen species. A total of 87 R₀ transgenicrice plants harboring a chimeric GST gene were generatedusing Agrobacterium mediated transformation. ThreeR₂ lines homozygous for the transgene were assayed for GST activityand had higher GST and glutathione peroxidase activities thannon-transformants.Seedlings of the transgenic lines demonstrated greatly enhanced germination andgrowth rates at low temperature grown under submergence. The GST transgeniclines should be useful for breeding rice cultivars suitable for direct-seedingcultivation in cooler temperate regions.     

A hyperthermostable D-ribose-5-phosphate isomerase from Pyrococcus horikoshii characterization and three-dimensional structure

A gene homologous to D-ribose-5-phosphate isomerase (EC 5.3.1.6) was found in the genome of Pyrococcus horikoshii. D-ribose-5-phosphate isomerase (PRI) is of particular metabolic importance since it catalyzes the interconversion between the ribose and ribulose forms involved in the pentose phosphate cycle and in the process of photosynthesis. The gene consisting of 687 bp was overexpressed in Escherichia coli, and the resulting enzyme showed activity at high temperatures with an optimum over 90 degrees C. The crystal structures of the enzyme, free and in complex with D-4-phosphoerythronic acid inhibitor, were determined. PRI is a tetramer in the crystal and in solution, and each monomer has a new fold consisting of two alpha/beta domains. The 3D structures and the characterization of different mutants indicate a direct or indirect catalytic role for the residues E107, D85, and K98.     

Protective effects of thrombopoietin and stem cell factor on X-irradiated CD34+ megakaryocytic progenitor cells from human placental and umbilical cord blood

In previous studies we characterized the radiosensitivity of CFU-megakaryocytes from human placental and umbilical cord blood and the effects of various early-acting cytokines. We found that the maximal clonal growth of CFU-megakaryocytes in vitro and maximal protection against X-ray damage were supported by a combination of thrombopoietin and stem cell factor. However, the mechanism by which the two cytokines exert a synergistic effect remained unclear, so we extended these studies to investigate the radioprotective action of synergistic thrombopoietin and stem cell factor on the survival of X-irradiated CD34(+) CFU-megakaryocytes. A combination of thrombopoietin and stem cell factor led to activation of mitogen-activated protein kinase and extracellular signal-regulated protein kinase and to suppression of caspase 3 in X-irradiated CD34(+) cells. When PD98059 and various synthetic substrates-specific inhibitors of these proteins-were used, the combination had less effect on the clonal growth of X-irradiated CD34(+) CFU-megakaryocytes. However, the addition of wortmannin, a specific inhibitor of the phosphatidylinositol-3 kinase pathway, did not alter the synergistic action of thrombopoietin plus stem cell factor. We suggest that part of this synergistic effect can be explained by activation of mitogen-activated protein kinase and extracellular signal-regulated protein kinase and by suppression of the caspase cascade.     

Role of aromatase and androgen receptor expression in gonadal sex differentiation of ZW/ZZ-type frogs,Rana rugosa

To elucidate the mechanisms of amphibian gonadal sex differentiation, we examined the expression of aromatase and androgen receptor (AR) mRNAs for days 17-31 after fertilization. The effects of inhibitors and sex steroid hormones were also examined. In ZZ males, expression of AR decreased after day 19, while aromatase expression was low throughout the sampling period. Males treated with 17beta-estradiol (E2) showed increasing aromatase expression after day 21, and formed ovaries. AR antagonist treatment also induced high-level aromatase expression and ovarian differentiation. In males co-treated with an aromatase inhibitor and E2, the undifferentiated gonads developed into testes despite high-level aromatase expression. Males treated with androgen and E2 before and during an estrogen sensitive period, respectively, also formed testes. In ZW females, AR expression persisted at a low-level, while aromatase expression increased after day 18. Short-term treatment with an aromatase inhibitor was ineffective in preventing ovarian differentiation, whereas long-term treatment resulted in testes developing from ovarian structure. Compared with the ZZ males and ZW females, WW females did not exhibit detectable expression of AR, suggesting that the active AR gene(s) itself, or a putative gene regulating AR gene expression, is located on Z chromosomes. From the time lag of aromatase expression between ZW females and ZZ males treated with E2 and the effect of AR antagonist, it was found that in males elevated AR expression suppresses aromatase expression directly or indirectly. Consequently, endogenous androgens, accumulated by blocking estrogen biosynthesis, induced testicular differentiation. The gonadogenesis of males is dependent on sex hormone, whereas that of females has evolved to hormone-independence.     

Immunoelectron microscopic study for histamine in the gastric enterochromaffin-like cells of rats treated with the proton pump inhibitor lansoprazole

The enterochromaffin-like (ECL) cells of the gastric mucosa in animals play an important role in gastric acid secretion. They contain few granules and numerous secretory vesicles and microvesicles. They operate under the control of circulating gastrin. In the present study, we conducted an immunoelectron microscopic study for histamine (HA) in the ECL cells of rats given the proton pump inhibitor lansoprazole (LP), which is known to induce hypergastrinemia. The pre-embedding indirect immunoperoxidase procedure utilized a mouse monoclonal antibody AHA-2 against glutaraldehyde-conjugated HA. Rats received LP (50 g/kg per day, subcutaneously) over a period of a month, and developed hypertrophy of the ECL cells in the stomach. It was clearly demonstrated that HA was located to a much higher degree in the cytoplasm of ECL cells of LP-treated rats than in normal rats. HA immunoreactivity was observed in the cores of the granules and secretory vesicles of the ECL cells in all the rats, but in the LP-treated rats it was observed in the cores of the newly developed vacuoles as well. These results may suggest that HA may be actively generated in the cytoplasm of the hypertrophic ECL cells of LP-treated rats. Also suggested in the present study is that HA is instrumental in the transformation of granules into secretory vesicles and in their consequent enlargement, and that vacuoles are formed by the fusion of large secretory vesicles. Furthermore, the finding that relatively little HA immunoreactivity existed in the vacuoles may suggest that the vacuoles actively degrade superfluous secretory products (for example, HA) through enhanced autophagocytosis and/or oxidative stress. Another possibility may be that the membrane-bounded structure regarded as the vacuoles in this study might actually be an invagination structure produced as a result of successive series of exocytosis through which the secretory vesicles actively and rapidly release HA.     

Rapid patterning of Dictyostelium discoideum cells under confined geometry and its relation to differentiation

The following was recently reported by Bonner et al. (1995): (1) Rapid differentiation occurred into two zones in Dictyostelium discoideum cells confined in a fine glass capillary. The cells in the anterior zone exposed to the air appear similar to prestalk cells, while the posterior zone isolated from the air mimics prespore cells. (2) The volumes of the two zones are proportional to each other for different sized cell masses, and the proportion is the same as that in normal migrating slugs. We investigated the nature of this newly discovered rapid differentiation in a slightly modified geometry. Exponentially growing cells were harvested, washed to remove external nutrients, and pelleted by centrifugation. Subsequently, a small drop of the pelleted (starved) cells was placed on a slide glass and then confined in a two-dimensional space between the slide glass and a coverslip, with help of spacers whose thickness varied from 25 to 100 μm. As a result, a dark zone, which looked optically different, emerged within several minutes in the periphery of the disc of the confined cells, corresponding to the zonation in a capillary as previously reported. When the width of the peripheral zone was measured for more than 30 samples of different diameters for each thickness of the spacers, the width was found to be always about 100 μm, irrespective of the size difference of the cell mass placed. This seems to be contradictory to the previous observation made by Bonner et al. (1995). We also examined oxygen concentration dependence on the zone width. The zone width was found to be independent of the oxygen concentration at low concentrations, but increased rapidly at high concentrations. A reaction-diffusion mechanism for formation of the zone and possible involvement of atmospheric oxygen (O₂) in the initial steps of cell differentiation and pattern formation is discussed.     

Cytotoxic cycloartane-type triterpenes from Combretum quadrangulare

Seven novel cycloartane-type triterpenes were isolated from Combretum quadrangulare, and their structures were elucidated on the basis of spectral analysis. All these compounds were tested for their cytotoxicity against murine colon 26-L5 carcinoma cells. Methyl quadrangularate B (2) and methyl quadrangularate D (4) exhibited potent cytotoxicity having ED₅₀ values 9.54 and 5.42 μM, respectively.     

p38-Mediated phosphorylation of Eps15 endocytic adaptor protein

Epidermal growth factor receptor pathway substrate 15 (Eps15) has been suggested to be involved in the endocytosis of cell surface receptors, including epidermal growth factor receptor (EGFR). Eps15 is phosphorylated at Tyr-849 upon stimulation with EGF during endocytic processes. In the present study, we found that stimulation of HeLa cells with EGF or TNF-α induced transient phosphorylation of Eps15 at Ser-796. Inhibition of p38 completely blocked phosphorylation and recombinant p38α directly phosphorylated the residue. These results demonstrate a novel stress kinase-mediated signaling pathway to Eps15 endocytic adapter protein.     

Contribution of the trifluoroacetyl group in the thermodynamics of antigen–antibody binding

We analyzed the binding of the 7C8 antibody to the chloramphenicol phosphonate antigens—one containing a trifluoroacetyl group (CP‐F) and the other containing an acetyl group (CP‐H)—by using isothermal titration calorimetry (ITC). The thermodynamic difference due to the substitution of F by H was evaluated using free energy calculations based on molecular dynamics (MD) simulations. We have previously shown that another antibody, namely, 6D9, binds more weakly to CP‐H than to CP‐F, mainly due to the different hydration free energies of the dissociated state and not due to the unfavorable hydrophobic interactions with the antibody in the bound state. Unlike in the binding of the trifluoroacetyl group with 6D9, in its binding with 7C8, it is exposed to the solvent, as seen in the crystal structure of the complex of 7C8 with CP‐F. The thermodynamic analysis performed in this study showed that the binding affinity of 7C8 for CP‐H is similar to that for CP‐F, but this binding to CP‐H is accompanied with less favorable enthalpy and more favorable entropy changes. The free energy calculations indicated that, upon the substitution of F by H, enthalpy and entropy changes in the associated and dissociated states were decreased, but the magnitude of enthalpy and entropy changes in the dissociated state was larger than that in the associated state. The differences in binding free energy, enthalpy, and entropy changes determined by the free energy calculations for the substitution of F by H are in good agreement with the experimental results. Copyright © 2009 John Wiley & Sons, Ltd.