OCCURRENCE AND FORMATION OF γ-GLUTAMYLPUTRESCINE IN MAMMALIAN BRAIN

—An unknown radioactive compound was detected in the basic fraction of the trichloroacetic acid extract of rat brain injected with radioactive putrescine. This compound was purified from bovine brain and identified as γ-glutamylputrescine by comparison of its behaviour with that of the synthesized glutamylamides. The amide seemed to be metabolized as rapidly as putrescine in rat brain.     

Assessment of Still and Moving Images in the Diagnosis of Gastric Lesions Using Magnifying Narrow-Band Imaging in a Prospective Multicenter Trial

Objectives

Magnifying narrow-band imaging (M-NBI) is more accurate than white-light imaging for diagnosing small gastric cancers. However, it is uncertain whether moving M-NBI images have additional effects in the diagnosis of gastric cancers compared with still images.

Design

A prospective multicenter cohort study.

Methods

To identify the additional benefits of moving M-NBI images by comparing the diagnostic accuracy of still images only with that of both still and moving images. Still and moving M-NBI images of 40 gastric lesions were obtained by an expert endoscopist prior to this prospective multicenter cohort study. Thirty-four endoscopists from ten different Japanese institutions participated in the prospective multicenter cohort study. Each study participant was first tested using only still M-NBI images (still image test), then tested 1 month later using both still and moving M-NBI images (moving image test). The main outcome was a difference in the diagnostic accuracy of cancerous versus noncancerous lesions between the still image test and the moving image test.

Results

Thirty-four endoscopists were analysed. There were no significant difference of cancerous versus noncancerous lesions between still and moving image tests in the diagnostic accuracy (59.9% versus 61.5%), sensitivity (53.4% versus 55.9%), and specificity (67.0% versus 67.6%). And there were no significant difference in the diagnostic accuracy between still and moving image tests of demarcation line (65.4% versus 65.5%), microvascular pattern (56.7% versus 56.9%), and microsurface pattern (48.1% versus 50.9%). Diagnostic accuracy showed no significant difference between the still and moving image tests in the subgroups of endoscopic findings of the lesions.

Conclusions

The addition of moving M-NBI images to still M-NBI images does not improve the diagnostic accuracy for gastric lesions. It is reasonable to concentrate on taking sharp still M-NBI images during endoscopic observation and use them for diagnosis.

Trial registration

Umin.ac.jp UMIN-CTR000008048     

Light activates H2 15O flow in rice: Detailed monitoring using a positron-emitting tracer imaging system (PETIS)

Water (H₂ ¹⁵O) translocation from the roots to the top of rice plants ( Oryza saliva L. cv. Nipponbare) was visualized over time by a positron-emitting tracer imaging system (PETIS). H₂ ¹⁵O flow was activated 8 min after plants were exposed to bright light (1 500 μmol m⁻² s⁻¹). When the light was subsequently removed, the flow gradually slowed and completely stopped after 12 min. In plants exposed to low light (500 μmol m⁻² s⁻¹), H₂ ¹⁵O flow was activated more slowly, and a higher translocation rate of H₂ ¹⁵O was observed in the same low light at the end of the next dark period. NaCl (80 m M ) and methylmercury (1 m M ) directly suppressed absorption of H₂ ¹⁵O by the roots, while methionine sulfoximine (1 m M ), abscisic acid (10 μ M ) and carbonyl cyanide m -chlorophenylhydrazone (10 m M ) were transported to the leaves and enhanced stomatal closure, reducing H₂ ¹⁵O translocation.     

Purification and characterization of alpha-keto amide reductase from Saccharomyces cerevisiae

An NADPH-dependent alpha-keto amide reductase was purified from Saccharomyces cerevisiae. The molecular mass of the native enzyme was estimated to be 33 and 36 kDa by gel filtration chromatography and SDS-polyacrylamide gel electrophoresis, respectively. The purified enzyme showed a reducing activity not only for aromatic alpha-keto amides but also for aliphatic and aromatic alpha-keto esters. The internal sequence of the enzyme was identical with that of a hypothetical protein (ORF YDL 124w) coded by yeast chromosome IV.     

Inhibition of sphingomyelinase activity helps to prevent neuron death caused by ischemic stress

Magnesium-dependent neutral sphingomyelinase (N-SMase) present in plasma membranes is an enzyme that can be activated by stress in the form of inflammatory cytokines, serum deprivation, and hypoxia. The design of small molecule N-SMase inhibitors may offer new therapies for the treatment of inflammation, ischemic injury, and cerebral infarction. Recently, we synthesized a series of difluoromethylene analogues (SMAs) of sphingomyelin. We report here the effects of SMAs on the serum/glucose deprivation-induced death of neuronally differentiated pheochromocytoma (PC-12) cells and on cerebral infarction in mice. SMAs inhibited the enhanced N-SMase activity in the serum/glucose-deprived PC-12 cells, and thereby suppressed the apoptotic sequence: ceramide formation, c-Jun N-terminal kinase phosphorylation, caspase-3 activation, and DNA fragmentation in the nuclei. Administration of SMA-7 (10 mg/kg i.v.) with IC50= 3.3 microM to mice whose middle cerebral arteries were occluded reduced significantly the size of the cerebral infarcts, compared to the control mice. These results suggest that N-SMase is a key component of the signaling pathways in cytokine- and other stress-induced cellular responses, and that inhibiting or stopping N-SMase activity is an important strategy to prevent neuron death from ischemia.     

A mouse model for cerebral babesiosis

Clinical symptoms and pathology observed in the cattle infected with Babesia bovis are quite similar to those of human cerebral malaria. Mechanisms involved in the pathogenesis of cerebral babesiosis, however, are still poorly understood because of the lack of a suitable experimental animal model. In this report, Masayoshi Tsuji and his colleagues describe B. bovis infection in severe combined immunodeficiency (SCID) mice, whose circulating red blood cells (RBCs) have been substituted with bovine RBCs (Bo-RBC-SCID mice). The infected mice not only develop a substantial level of parasitemia, but also show nerve symptoms and pathology similar to those observed in infected cattle.     

Changes in Chlorophyll a and b Content in Dark-Incubated Cotyledons Excised from Illuminated Seedlings: THE EFFECT OF CALCIUM

Cucumber seedlings were illuminated for various time periods, cotyledons excised, placed in the dark, and changes in chlorophyll a and b content monitored. During the dark periods, chlorophyll b content decreased while chlorophyll a did not. When the illumination time was lengthened, the percentage of chlorophyll b decomposition from initial levels decreased. Ca²⁺ at 50 millimolar prevented the decrease in chlorophyll b and caused a decrease in chlorophyll a. The effect of Ca²⁺ decreased with increased illumination time. Cycloheximide and chloramphenicol inhibited chlorophyll b decrease, but did not induce chlorophyll a decrease.     

Galactosialidosis: molecular heterogeneity in biosynthesis and processing of protective protein for β-galactosidase

Summary Biosynthesis and processing of the protective protein for -galactosidase in normal and galactosialidosis fibroblasts were investigated using specific antiserum preparations. A 45-kd precursor was processed to a mature 30-kd protein in normal fibroblasts. The mature protective protein was not detected in any of the twelve galactosialidosis fibroblast strains examined in this study. The precursor was not detected in two cases and in the others was of heterogeneous molecular weight, i.e., normal, abnormally low, or abnormally high. These molecular abnormalities were not correlated with clinical manifestations of the patients.     

Ornithine decarboxylase antizyme upregulates DNA-dependent protein kinase and enhances the nonhomologous end-joining repair of DNA double-strand breaks in human oral cancer cells

Ornithine decarboxylase (ODC) antizyme targets ODC for ubiquitin-independent proteosome degradation, thereby inhibiting polyamine synthesis. It has been shown to regulate DNA methylation and has tumor suppressor activity. Increasing evidence suggested that antizyme may also have ODC-independent functions. Here, we report that antizyme plays a role in DNA double-strand break repairs. A zinc-inducible human antizyme gene expression vector was transfected into UM1 human oral squamous cancer cells that do not express endogenous antizyme. The resultant upregulated genes were screened by cDNA arrays and confirmed by quantitative real-time polymerase chain reaction. DNA-dependent protein kinase including its catalytic subunit DNA-PKcs and regulatory subunit Ku70, two key proteins of the DNA damage repair machinery, was significantly upregulated after ectopic expression of antizyme. Consistently, we found that UM1 cells are sensitive to gamma irradiation and deficient in DNA damage repairs, as shown by radio-sensitivity and Comet assays. Ectopic expression of antizyme increased radio-resistance of UM1 cells and restored their capacity of DNA damage repairs to the level of UM2 cells that have an identical genetic background but express endogenous antizyme. Plasmid end-joining assays confirmed that antizyme enhances the ability of UM1 cells to repair DNA double-strand breaks by the nonhomologous end-joining pathway.     

Phorbol ester-dependent phosphorylation regulates the association of p57/coronin-1 with the actin cytoskeleton

The p57/coronin-1 protein is a member of the coronin family of actin-binding proteins, which are characterized by the presence of WD (tryptophan/aspartic acid) repeats and a coiled-coil motif in the molecule. It is selectively expressed in immune cells and has been suggested to play crucial roles in leukocyte functions, including cell migration and phagocytosis. In this study we examined the effects of p57/coronin-1 phosphorylation on the association of the protein with actin. Treatment of HL60 human leukemic cells or p57/coronin-1-transfected HEK293 cells with phorbol 12-myristate 13-acetate (PMA) reduced the association of p57/coronin-1 with the actin cytoskeleton, as indicated by cell fractionation experiments and by fluorescence microscopic observation. Two-dimensional gel electrophoresis of HL60 cell lysate revealed that p57/coronin-1 was phosphorylated upon PMA stimulation of the cells, giving two major and two minor spots of phosphorylated forms, each with distinct isoelectric points. The p57/coronin-1 molecules associated with the cytoskeleton in PMA-treated HL60 cells were phosphorylated at lower levels than those recovered in the cytosolic fraction. In addition, p57/coronin-1 co-sedimented with F-actin polymerized in vitro had lower phosphorylation levels than the molecules remaining in the supernatant. By affinity chromatographic analysis using anti-p57/coronin-1 antibody-conjugated Sepharose, p57/coronin-1 derived from PMA-treated HL60 cells showed lower affinity for actin than that from untreated cells. Finally, recovery of p57/coronin-1 in the actin cytoskeleton-rich fraction from neutrophil-like differentiated HL60 cells decreased during phagocytosis, concomitant with enhanced phosphorylation of p57/coronin-1. These results strongly suggest that the phosphorylation of p57/coronin-1 down-regulates its association with actin and modulates the reorganization of actin-containing cytoskeleton.