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.     

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.     

A subunit of the mammalian oligosaccharyltransferase, DAD1, interacts with Mcl-1, one of the bcl-2 protein family

DAD1 is a mammalian homologue of Saccharomyces cerevisiae Ost2p, a subunit of the oligosaccharyltransferase complex. Loss of its function induces apoptosis in hamster BHK21 cells. By means of a two-hybrid method involving DAD1 as bait, the C-terminal region of Mcl-1, one of the bcl-2 family, was isolated. Consistently, DAD1 binds well to Mcl-1 in COS cells when overexpressed. On deletion analysis, the C-terminal domain of Mcl-1 containing BH(2) (bcl-2 homologous domain) was found to be essential for the interaction with DAD1. On the other hand, the C-terminal half of DAD1 was concluded to be essential for the interaction with Mcl-1. Surprisingly, a DeltaC-DAD1 mutant lacking only 4 amino acid residues from the C-terminus did not complement the tsBN7 mutation, while it interacted well with Mcl-1. In contrast, DeltaN-DAD1 lacking 20 amino acid residues from the N-terminus still exhibited the ability to complement the tsBN7 mutation. Thus, the C-terminus of DAD1 was suggested to play an important role in N-linked glycosylation and to complement the tsBN7 mutation. Mcl-1 may be required for the inhibition of apoptotic cell death caused by a loss of DAD1.     

Inhibition of N-linked glycosylation causes apoptosis in hamster BHK21 cells

The tsBN7 cell line is one of the temperature-sensitive mutants for cell proliferation derived from hamster BHK21 cell line. It has a mutation in the DAD1 gene and enters apoptosis at the restrictive temperature of 39 degrees C. The defect of Dad1p causes a loss of N-linked glycosylation; therefore, it was thought that an inhibition of N-linked glycosylation induced apoptosis.However, tunicamycin, a potent inhibitor of N-linked glycosylation, had not caused apoptosis in wild-type BHK21 cells. In order to clarify this discrepancy, wild-type BHK21 cells treated with tunicamycin and tsBN7 cells incubated at 39.5 degrees C were examined by the annexin V staining and TUNEL methods. Both methods showed that tunicamycin induces apoptosis in wild-type BHK21 cells, similar to the defect of Dad1p. Thus, we concluded that loss of N-linked glycosylation causes apoptosis.     

Orbit, a novel microtubule-associated protein essential for mitosis in Drosophila melanogaster

We describe a Drosophila gene, orbit, that encodes a conserved 165-kD microtubule-associated protein (MAP) with GTP binding motifs. Hypomorphic mutations in orbit lead to a maternal effect resulting in branched and bent mitotic spindles in the syncytial embryo. In the larval central nervous system, such mutants have an elevated mitotic index with some mitotic cells showing an increase in ploidy. Amorphic alleles show late lethality and greater frequencies of hyperploid mitotic cells. The presence of cells in the hypomorphic mutant in which the chromosomes can be arranged, either in a circular metaphase or an anaphase-like configuration on monopolar spindles, suggests that polyploidy arises through spindle and chromosome segregation defects rather than defects in cytokinesis. A role for the Orbit protein in regulating microtubule behavior in mitosis is suggested by its association with microtubules throughout the spindle at all mitotic stages, by its copurification with microtubules from embryonic extracts, and by the finding that the Orbit protein directly binds to MAP-free microtubules in a GTP-dependent manner.