Site-specific induction of lipid peroxidation by iron in charged micelles

Generation of hydroxyl radicals by the Fenton reaction resulted in lipid peroxidation of linoleic acid (LA) (H2O2-Fe2+-induced lipid peroxidation) in positively charged tetradecyltrimethylammonium bromide (TTAB) micelles, but not in negatively charged sodium dodecyl sulfate (SDS) micelles. However, more OH radicals formed via the Fenton reaction were trapped by N-t-butyl-alpha-phenylnitrone (PBN) in SDS micelles than in TTAB micelles. When detergent-dispersed LA was contaminated with linoleic acid hydroperoxide (LOOH), lipid peroxidation was catalyzed by Fe2+ via reductive cleavage of LOOH (LOOH-Fe2+-induced lipid peroxidation), and Fe2+ was oxidized simultaneously in SDS micelles, even when H2O2 was not present. In contrast, LOOH-Fe2+-induced lipid peroxidation and simultaneous oxidation of Fe2+ were not observed in TTAB micelles. An ESR spectrum presumed to be due to an alkoxy radical trapped by PBN was also detected in SDS micelles, but not in TTAB micelles in the LOOH-Fe2+-induced lipid peroxidation system. The results are discussed in the light of the localization of iron, the unsaturated bonding moiety of LA, the OOH-group of LOOH, and the trapping site of PBN in different charged micelles.     

Easy and Rapid Detection of Mumps Virus by Live Fluorescent Visualization of Virus-Infected Cells

Mumps viruses show diverse cytopathic effects (CPEs) of infected cells and viral plaque formation (no CPE or no plaque formation in some cases) depending on the viral strain, highlighting the difficulty in mumps laboratory studies. In our previous study, a new sialidase substrate, 2-(benzothiazol-2-yl)-4-bromophenyl 5-acetamido-3,5-dideoxy-α-D-glycero-D-galacto-2-nonulopyranosidonic acid (BTP3-Neu5Ac), was developed for visualization of sialidase activity. BTP3-Neu5Ac can easily and rapidly perform histochemical fluorescent visualization of influenza viruses and virus-infected cells without an antiviral antibody and cell fixation. In the present study, the potential utility of BTP3-Neu5Ac for rapid detection of mumps virus was demonstrated. BTP3-Neu5Ac could visualize dot-blotted mumps virus, virus-infected cells, and plaques (plaques should be called focuses due to staining of infected cells in this study), even if a CPE was not observed. Furthermore, virus cultivation was possible by direct pick-up from a fluorescent focus. In conventional methods, visible appearance of the CPE and focuses often requires more than 6 days after infection, but the new method with BTP3-Neu5Ac clearly visualized infected cells after 2 days and focuses after 4 days. The BTP3-Neu5Ac assay is a precise, easy, and rapid assay for confirmation and titration of mumps virus.     

aPKC acts upstream of PAR-1b in both the establishment and maintenance of mammalian epithelial polarity

BACKGROUND: aPKC and PAR-1 are required for cell polarity in various contexts. In mammalian epithelial cells, aPKC localizes at tight junctions (TJs) and plays an indispensable role in the development of asymmetric intercellular junctions essential for the establishment and maintenance of apicobasal polarity. On the other hand, one of the mammalian PAR-1 kinases, PAR-1b/EMK1/MARK2, localizes to the lateral membrane in a complimentary manner with aPKC, but little is known about its role in apicobasal polarity of epithelial cells as well as its functional relationship with aPKC. RESULTS: We demonstrate that PAR-1b is essential for the asymmetric development of membrane domains of polarized MDCK cells. Nonetheless, it is not required for the junctional localization of aPKC nor the formation of TJs, suggesting that PAR-1b works downstream of aPKC during epithelial cell polarization. On the other hand, aPKC phosphorylates threonine 595 of PAR-1b and enhances its binding with 14-3-3/PAR-5. In polarized MDCK cells, T595 phosphorylation and 14-3-3 binding are observed only in the soluble form of PAR-1b, and okadaic acid treatment induces T595-dependent dissociation of PAR-1b from the lateral membrane. Furthermore, T595A mutation induces not only PAR-1b leakage into the apical membrane, but also abnormal development of membrane domains. These results suggest that in polarized epithelial cells, aPKC phosphorylates PAR-1b at TJs, and in cooperation with 14-3-3, promotes the dissociation of PAR-1b from the lateral membrane to regulate PAR-1b activity for the membrane domain development. CONCLUSIONS: These results suggest that mammalian aPKC functions upstream of PAR-1b in both the establishment and maintenance of epithelial cell polarity.     

Ser-59 is the major phosphorylation site in alphaB-crystallin accumulated in the brains of patients with Alexander's disease

The phosphorylation state of alphaB-crystallin accumulated in the brains of two patients with Alexander's disease (one infantile and one juvenile type) was determined by means of SDS-PAGE or isoelectric focusing of soluble and insoluble fractions of brain extracts and subsequent western blot analysis with specific antibodies against alphaB-crystallin and each of three phosphorylated serine residues. The level of mammalian small heat shock protein of 25-28 kDa (Hsp27) in the same fraction was also estimated by western blot analysis. The majority of alphaB-crystallin was detected in the insoluble fraction of brain homogenates and phosphorylation was preferentially observed at Ser-59 in both cases. A significant level of phosphorylation at Ser-45 but not Ser-19 was also detected. Hsp27 was found at considerable levels in the insoluble fractions. alphaB-crystallin and phosphorylated forms were detected in the cerebrospinal fluid of patient with the juvenile type. AlphaB-crystallin and phosphorylated forms were also detectable at considerable levels in the insoluble fraction of brain homogenates from patients with Alzheimer's disease and aged controls. The phosphorylation site was mostly at Ser-59 in all cases. Immunohistochemically, alphaB-crystallin was stained in Rosenthal fibers in brains of patients with Alexander's disease and their peripheral portions were immunostained with antibodies recognizing phosphorylated Ser-59. These results indicate that the major phosphorylation site in alphaB-crystallin in brains of patients with Alexander's disease or Alzheimer's disease as well as in aged controls is Ser-59.     

A miRNA machinery component DDX20 controls NF-κB via microRNA-140 function

Hepatocellular carcinoma is the third leading cause of cancer mortality worldwide, but the molecular mechanisms in tumorigenesis remain largely unknown. Previously, a DEAD-box protein DDX20, a component of microRNA-containing ribonucleoprotein complexes, was identified as a liver tumor suppressor candidate in an oncogenomics-based in vivo RNAi screen. However, the molecular mechanisms were unknown. Here, we show that deficiency of DDX20 results in the enhancement of NF-κB activity, a crucial intracellular signaling pathway closely linked with hepatocarcinogenesis. While DDX20 normally suppresses NF-κB activity by regulating NF-κB-suppressing miRNA-140 function, this suppressive effect was lost in DDX20-deficient cells. The impairment of miRNA function due to DDX20 deficiency appears to be miRNA species-specific at the point of loading miRNAs into the RNA-induced silencing complex. These results indicate that DDX20 deficiency enhances NF-κB activity by impairing the NF-κB-suppressive action of microRNAs, and suggest that dysregulation of the microRNA machinery components may also be involved in pathogenesis in various human diseases.     

Study on immunocapture-chemiluminescence assay of lipase activity in a biological sample.

A new approach for the determination of lipase (triacylglycerol lipase, EC.3.1.1.3) activity in a biological sample was investigated by combining an immunocapture technique with a chemiluminescence (CL) assay method in order to eliminate interference with CL detection. The proposed method consists of an immunocapture step to trap lipase and a subsequent step for CL detection of the activity of the captured lipase. The CL detection is based on the luminol-hydrogen peroxide (H(2)O(2))-horseradish peroxidase (HRP) reaction and utilizes a proenhancer substrate [a lauric acid ester of 2-(4-hydroxyphenyl)-4,5-diphenylimidazole (HDI)] which liberates an active enhancer, HDI, by enzymatic hydrolysis. A polyclonal antibody prepared with porcine pancreas lipase was used for the immunocapture. The proposed immunocapture-CL method effectively eliminated the interference with the CL reaction from biological components and enabled the determination of spiked porcine pancreas lipase activity in serum samples in the range 0.41-1.1 U(HDI) (1 U(HDI) corresponds to the amount which liberates 1 pmol HDI/min at 37 degrees C from the substrate). The method was further applied to the assay of the activity for human pancreas lipase in serum and the results showed good correlation (r = 0.871) with those by the conventional colorimetric method.     

Unusual cytologic findings in low grade papillary transitional cell carcinoma

OBJECTIVE: To describe cases of low grade papillary transitional cell carcinoma (LG-pTCC) with a low nuclear cytoplasmic (N/C) ratio and unusual cytologic patterns with many isolated, single neoplastic cells. STUDY DESIGN: We defined the following unusual cytologic findings as "isolated, single cell pattern": (1) numerous single cells sometimes with a few flat cell clusters; (2) very low N/C ratio; (3) angulation of cytoplasmic contour; (4) pale, homogeneous cytoplasm; (5) hyperchromatic nuclei with an uneven contour; (6) monotonous cytologic appearance; and (7) clear background. We studied 2,956 cytologic specimens of voided urine from 114 LG-pTCC patients at our university hospital during a 10-year period. RESULTS: Thirty-six specimens had the isolated, single cell pattern. The isolated, single cell pattern showed less celllular atypia than does the typical pattern of LG-pTCC. On histology the cases with the isolated, single cell pattern showed a papillary structure with an erosive surface and were composed of mildly atypical neoplastic cells with very low N/C ratios. CONCLUSION: Some LG-pTCCs show many single, atypical transitional cells.     

Quantitative footprinting analysis

This review outlines the steps for obtaining relative constants for drugs from footprinting data. After correcting the autoradiographic spot intensities for differing amounts of radioactive DNA loaded into the lanes of a sequencing gel, footprinting plots, showing individual spot intensities as a function of drug concentration, are constructed. The initial relative slopes of footprinting plots are proportional to the binding constant of the drug for its DNA sites. Slopes of plots outside the drug binding sites can be used to identify locations of altered DNA structure. It illustrates the power of quantitative footprinting analysis by analyzing the binding of the antiviral agent netrospin to a 139-base pair restriction fragment in the presence of the antitumor agent actinomycin D. While two netrospin binding regions are unaffected by actinomycin D a third region experiences enhanced binding in the presence of the antitumor agent.