Immunohistochemical localization of hepatocyte growth factor activator (HGFA) in developing mouse liver tissues. Heterogeneous distribution of HGFA protein.

Hepatocyte growth factor activator (HGFA) can activate the single-chain hepatocyte growth factor (HGF) required for embryonic development. We studied the immunohistochemical (IHC) localization of HGFA in adult mouse liver and its developmental changes from embryonic day 12 to postnatal day 30. A heterogeneous distribution of HGFA was observed in adult liver tissues. The hepatocytes around the hepatic veins were preferentially positive for HGFA, whereas those in other areas were negative. Depending on the vascular diameter, the hepatic veins were bordered by a one- to three-cell-thick layer of hepatocytes positive for HGFA, which showed evidence of cell-cell heterogeneity in staining intensity. Immunoelectron microscopy detected ubiquitous distribution of the gold particle reaction product for HGFA in the cytoplasm of these hepatocytes, especially in the rough endoplasmic reticulum. Developmental analysis indicated that there was hardly any staining of HGFA until postnatal day 0 and that noticeable staining was initially detected in the pericentral hepatocytes on postnatal day 3. Subsequently, immunoreactivity increased and the distinct staining pattern had been established by postnatal day 30. These results suggest that HGFA proteins are produced in the hepatocytes surrounding the efferent hepatic veins in the mouse and that development of the unique distributing pattern takes place postnatally.     

Reduction of lipid hydroperoxides by apolipoprotein B-100.

We have previously isolated two proteins which can reduce phosphatidylcholine hydroperoxide (PC-OOH) from human blood plasma and identified one of the proteins as apolipoprotein A-I (Mashima, R. , et al. (1998) J. Lipid Res. 39, 1133-1140). In the present study we have identified the other protein as apolipoprotein B-100 (apo B-100) by amino acid sequence analysis of its tryptic peptides. The reactivity of lipid hydroperoxides with apo B-100 decreased in the order of PC-OOH > linoleic acid hydroperoxide > cholesteryl ester hydroperoxide under our experimental conditions. Pretreatment of apo B-100 with chloramine T, an oxidant of methionine, diminished the PC-OOH-reducing activity, indicating that some of 78 methionines are responsible for the reduction of PC-OOH. Despite the presence of 6 methionines in albumin, albumin was inactive to reduce PC-OOH. Free methionine was also inactive. These data suggest that the accessibility and binding of lipid hydroperoxides to the protein methionine residues are crucial for reduction of lipid hydroperoxides.     

Apoptosis resistance in tumor cells

Various antitumor agents induce apoptotic cell death in tumor cells. Since the apoptosis program in tumor cells plays a critical role in the chemotherapy-induced tumor cell killing, it is suggested that the defect in the signaling pathway of apoptosis could cause a new form of multidrug resistance in tumor cells. This article describes the recent findings concerning the mechanisms of chemotherapy-induced apoptosis and discusses the implication of apoptosis resistance in cancer chemotherapy. This revised version was published online in August 2006 with corrections to the Cover Date.     

Structure-activity relationship of brassinosteroids

The plant growth-promoting activities of brassinolide and brassinosteroids with different side chains were investigated by means of the Raphanus an     

Imaging of caspase-3 activation in HeLa cells stimulated with etoposide using a novel fluorescent probe.

Microscopic visualization of intracellular enzyme activity can provide information about the physiological role of the enzyme. Caspases are cysteine proteases that have critical roles in the execution of apoptosis. General fluorometric substrates of caspase-3, such as DEVD-MCA, are unsuitable for imaging because they are excited at short wavelength, so we designed and synthesized novel fluorescent probes that are excited at suitable wavelengths for detecting caspase-3 activity in living cells. Using one of these probes, we succeeded in microscopic visualization of caspase-3-like activity within HeLa cells treated with etoposide. The caspase-3-like activity was increased in the cytosol at first, then expanded to the whole cell.     

First isolation of Desulfovibrio from the human vaginal flora

Four Desulfovibrio species, including 2 subtypes of 1 species, namely, Desulfovibrio piger, Desulfovibrio desulfuricans MB subtype and Essex 6 subtype, Desulfovibrio fairfieldensis, and Desulfovibrio vulgaris, have been isolated from the human oral and intestinal flora, but not previously from the vaginal flora. They are opportunistic pathogens and have been considered as possible environmental and etiologic agents involved in ulcerative colitis and chronic periodontitis. We isolated Desulfovibrio intestinalis from vaginal specimens of four Japanese women; a species which has not been previously isolated from humans. The vaginal isolates were highly resistant to cefoxitin, piperacillin, and piperacillin-tazobactam but were susceptible to the other antimicrobial agents tested. Our findings suggested that vaginal Desulfovibrio species may be involved in gynecological or obstetric pathology, and provides additional information of the medical relevance on human Desulfovibrio species.     

Synthesis of a fluorogenic mucopolysaccharide by chondrocytes in cell culture with 4-methylumbelliferyl β-d-xyloside

Culture of chondrocytes in the presence of 4-methylumbelliferyl β-d-xyloside resulted in a synthesis of protein-free, fluorogenic chondroitin sulfate which was heterogeneous on DEAE-cellulose chromatography. Degradation of the major chromatographic fraction with chondroitinase-ABC yielded, in addition to a large quantity of Δ⁴-glucuronic acid-containing disaccharides, two flurogenic oligosaccharides of different size. Quantitative analysis showed that Δ⁴-glucuronic acid, galactose, xylose, and 4-methylumbelliferone were present in the small oligosaccharide fragment in a molar ratio of 1:2:1:1. Since these analytical data are analogous to those reported for glycopeptides derived from proteochondroitin sulfates, it may be suggested that 4-methylumbelliferyl β-d-xyloside replaces the need for xylosyl protein core in the normal synthesis of proteochondroitin sulfate with a resultant production of the unusual polysaccharide bearing the added xyloside at the reducing end.