A theoretical characterization method for non-spherical core-shell nanoparticles by XPS.

Core-shell nanoparticles (NPs) are active research areas for their unique properties and wide applications. By changing the elemental composition in the core and shell, a series of core-shell NPs with specific functions can be obtained, where the sizes of the core and shell also influence the properties. X-ray photoelectron spectroscopy (XPS) is useful in this context as a means of quantitatively analyzing such NPs. The empirical formula proposed by Shard [J. Phys. Chem. C, 2012, 116(31), 16806-16813] for calculating the shell thickness of the spherical core-shell NPs has been verified by Powell et al. [J. Phys. Chem. C, 2016, 120(39), 22730-22738] through a simulation of XPS with Simulation of Electron Spectra for Surface Analysis (SESSA) software. However, real core-shell NPs are not necessarily ideal spheres; such NPs can have rich shapes and uneven thicknesses. This work aims to extend the Shard formula to non-ideal core-shell NPs. We have used a Monte Carlo simulation method to study the XPS signal variation with the shell thickness for several modeled non-spherical shapes of core-shell NPs including some complex geometric structures which are numerically constructed with finite-element triangular meshes. Five types of non-spherical shapes, i.e. egg, ellipsoid, rod, rough-surface, and star shapes, are considered, while the size parameters are varied over a wide range. The equivalent radius and equivalent thickness are defined to characterize the average size of the nanoparticles for the use of the Shard formula. We have thus derived an extended Shard formula for the specific core-shell NPs, with which the relative error between the predicted shell thickness and the real thickness can be reduced to less than 10%.

Papaverine identified as an inhibitor of high mobility group box 1/receptor for advanced glycation end-products interaction suppresses high mobility group box 1-mediated inflammatory responses.

The interaction of high mobility group box 1 (HMGB1), which is secreted from immune and dying cells during cellular infection and injury, and receptor for advanced glycation end-products (RAGE) appears to be critical for acute and chronic inflammatory disorders. Here we designed a unique cyclic ß-hairpin peptide (Pepb2), which mimics the predicted RAGE-binding domain of HMGB1. Pepb2 competitively inhibited HMGB1/RAGE interaction. We then identified papaverine as a Pepb2 mimetic by in silico 3D-structural similarity screening from the DrugBank library. Papaverine was found to directly inhibit HMGB1/RAGE interaction. It also suppressed the HMGB1-mediated production of pro-inflammatory cytokines, IL-6 and TNF-α, in mouse macrophage-like RAW264.7 cells and bone marrow-derived macrophages. In addition, papaverine attenuated mortality in cecal ligation puncture-induced sepsis model mice. Taken together, these findings indicate that papaverine could become a useful therapeutic against HMGB1/RAGE-mediated sepsis and other inflammatory diseases.

Extended Mermin method for calculating the electron inelastic mean free path.

We propose an improved method for calculating electron inelastic mean free paths (IMFPs) in solids from experimental energy-loss functions based on the Mermin dielectric function. The "extended Mermin" method employs a nonlimited number of Mermin oscillators and allows negative oscillators to take into account not only electronic transitions, as is common in the traditional approaches, but also infrared transitions and inner shell electron excitations. The use of only Mermin oscillators naturally preserves two important sum rules when extending to infinite momentum transfer. Excellent agreement is found between calculated IMFPs for Cu and experimental measurements from elastic peak electron spectroscopy. Notably improved fits to the IMFPs derived from analyses of x-ray absorption fine structure measurements for Cu and Mo illustrate the importance of the contribution of infrared transitions in IMFP calculations at low energies.

Stage-specific expression of DNasegamma during B-cell development and its role in B-cell receptor-mediated apoptosis in WEHI-231 cells.

Here, we describe the non-redundant roles of caspase-activated DNase (CAD) and DNasegamma during apoptosis in the immature B-cell line WEHI-231. These cells induce DNA-ladder formation and nuclear fragmentation by activating CAD during cytotoxic drug-induced apoptosis. Moreover, these apoptotic manifestations are accompanied by inhibitor of CAD (ICAD) cleavage and are abrogated by the constitutive expression of a caspase-resistant ICAD mutant. No such nuclear changes occur during oxidative stress-induced necrosis, indicating that neither CAD nor DNasegamma functions under necrotic conditions. Interestingly, the DNA-ladder formation and nuclear fragmentation induced by B-cell receptor ligation occur in the absence of ICAD cleavage and are not significantly affected by the ICAD mutant. Both types of nuclear changes are preceded by the upregulation of DNasegamma expression and are strongly suppressed by 4-(4,6-dichloro-[1, 3, 5]-triazin-2-ylamino)-2-(6-hydroxy-3-oxo-3H-xanthen-9-yl)-benzoic acid (DR396), which is a specific inhibitor of DNasegamma. Our results suggest that DNasegamma provides an alternative mechanism for inducing nuclear changes when the working apoptotic cascade is unsuitable for CAD activation.

Calculations of Electron Inelastic Mean Free Paths. XI. Data for Liquid Water for Energies from 50 eV to 30 keV.

We calculated electron inelastic mean free paths (IMFPs) for liquid water from its optical energy-loss function (ELF) for electron energies from 50 eV to 30 keV. These calculations were made with the relativistic full Penn algorithm (FPA) that has been used for previous IMFP and electron stopping-power calculations for many elemental solids. We also calculated IMFPs of water with three additional algorithms: the relativistic single-pole approximation (SPA), the relativistic simplified SPA, and the relativistic extended Mermin method. These calculations were made using the same optical ELF in order to assess any differences of the IMFPs arising from choice of the algorithm. We found good agreement among the IMFPs from the four algorithms for energies over 300 eV. For energies less than 100 eV, however, large differences became apparent. IMFPs from the relativistic TPP-2M equation for predicting IMFPs were in good agreement with IMFPs from the four algorithms for energies between 300 eV and 30 keV but there was poorer agreement for lower energies. We calculated values of the static structure factor as a function of momentum transfer from the FPA. The resulting values were in good agreement with results from first-principles calculations and with inelastic X-ray scattering spectroscopy experiments. We made comparisons of our IMFPs with earlier calculations from authors who had used different algorithms and different ELF data sets. IMFP differences could then be analyzed in terms of the algorithms and the data sets. Finally, we compared our IMFPs with measurements of IMFPs and of a related quantity, the effective attenuation length (EAL). There were large variations in the measured IMFPs and EALs (as well as their dependence on electron energy). Further measurements are therefore required to establish consistent data sets and for more detailed comparisons with calculated IMFPs.

DLAD, a novel mammalian divalent cation-independent endonuclease with homology to DNase II.

In this report, we describe the molecular cloning and characterization of DLAD, a novel mammalian deoxy-ribonuclease homologous to DNase II. The full length cDNA for mouse DLAD has been cloned by polymerase chain reaction. The cDNA contains a 1065 bp open reading frame (ORF) encoding a 354 amino acid protein with a calculated molecular mass of 40 767. The predicted protein for DLAD shares 34.4% identity with DNase II. DLAD is also homologous to three predicted proteins, C07B5.5, F09G8.2 and K04H4.6, from the nematode Caenorhabditis elegans. Furthermore, the third ORF of the fowlpox virus genome is found to encode a DLAD homologue showing 37. 1% identity at the amino acid level. Northern blot analysis reveals that expression of the DLAD mRNA is highly restricted to the liver. DLAD mainly exists as a cytoplasmic protein with divalent cation-independent endonuclease activity and cleaves DNA to produce 3'-phosphoryl/5'-hydroxyl ends. It is active under a wide range of pH with maximum activity at pH 5.2. Among known DNase inhibitors tested, aurintricarboxylic acid and Zn(2+)are found to be effective inhibitors of the DLAD activity.

Mono(ADP-ribosyl)ation of Gi by eukaryotic cysteine-specific mono(ADP-ribosyl) transferase attenuates inhibition of adenylate cyclase by epinephrine.

Eukaryotic cysteine-specific mono(ADP-ribosyl)transferase, named ADP-ribosyltransferase C (Tanuma, S., Kawashima, K. and Endo, H. (1988) J. Biol. Chem. 263, 5485-5489), attenuates inhibition of adenylate cyclase in human platelet membranes by epinephrine. This attenuation appeared to result from mono(ADP-ribosyl)ation by ADP-ribosyltransferase C of the inhibitory guanine nucleotide-binding protein (Gi) of adenylate cyclase. These results indicate a role of ADP-ribosyltransferase C in regulation of hormonal control of the adenylate cyclase system.

Evidence of a regulatory role of the level of poly (ADP-ribose) in chromosomal proteins in metallothionein gene expression by glucocorticoids but not by heavy metals.

The induction capacity of dexamethasone, a synthetic glucocorticoid, for the synthesis of metallothionein was about the same as that of 3-aminobenzamide, which is an inhibitor of ADP-ribosylation of chromosomal proteins, in cultured mouse mammary tumor cells. Both inductions of metallothionein were temporally correlated with a decrease in the amount of endogenous poly (ADP-ribose) on nonhistone high-mobility-group 14 and 17 proteins. In contrast, the extent of cadmium-induced metallothionein synthesis was 2-3-times that of dexamethasone or 3-aminobenzamide. However, cadmium had essentially no effect on de-ADP-ribosylation of these proteins.

Differential DNases are selectively used in neuronal apoptosis depending on the differentiation state.

In this study, we investigate the roles of two apoptotic endonucleases, CAD and DNase gamma, in neuronal apoptosis. High expression of CAD, but not DNase gamma, is detected in proliferating N1E-115 neuroblastoma cells, and apoptotic DNA fragmentation induced by staurosporine under proliferating conditions is abolished by the expression of a caspase-resistant form of ICAD. After the induction of neuronal differentiation, CAD disappearance and the induction of DNase gamma occur simultaneously in N1E-115 cells. Apoptotic DNA fragmentation that occurs under differentiating conditions is suppressed by the downregulation of DNase gamma caused by its antisense RNA. The induction of DNase gamma is also observed during neuronal differentiation of PC12 cells, and apoptotic DNA fragmentation induced by NGF deprivation is inhibited by the antisense-mediated downregulation of DNase gamma. These observations suggest that DNA fragmentation in neuronal apoptosis is catalyzed by either CAD or DNase gamma depending on the differentiation state. Furthermore, DNase gamma is suggested to be involved in naturally occurring apoptosis in developing nervous systems.

Stimulation of human peripheral blood polymorphonuclear cell iodination by lignin-related substances.

Lignin is a heterogenous natural product composed of phenylpropane units and is usually associated with hemicellulose in its native state. Until now little attention has been paid to the potential therapeutic utility of lignified products. Natural lignified products are demonstrated in the present study to stimulate iodination significantly (incorporation of radioactive iodine into an acid-insoluble fraction) of human peripheral blood polymorphonuclear cells (PMN). This stimulation was significantly inhibited in the presence of myeloperoxidase inhibitors. These materials were almost completely deprived of their stimulation capacity by treatment with NaCIO2, but this capacity was not affected by severe treatment with H2SO4 or trifluoroacetic acid. Similar stimulating activity by chemically defined tannin-related polyphenolic compounds was observed. Degradation products or component units of lignin, and natural antitumor polysaccharides and their chemically modified derivatives (introduced with negatively or positively charged groups) and polysialoglycoproteins had little or no activity. The results indicate the importance of a polymerized phenolic structure for the stimulation of PMN iodination. Possible physiological relevance of the stimulation of iodination by lignified substances is discussed.

Identification in human erythrocytes of mono(ADP-ribosyl) protein hydrolase that cleaves a mono(ADP-ribosyl) Gi linkage.

A novel enzymatic activity, the hydrolysis of linkages between mono(ADP-ribose) and cysteine residues in Gi prepared by eukaryotic ADP-ribosyltransferase C [(1988) J. Biol. Chem. 263, 5485-5489] was found in the cytosol of human erythrocytes. The mono(ADP-ribosyl) Gi hydrolase, tentatively named ADP-ribosyl protein hydrolase C was partially purified by sequential chromatographies on DEAE-cellulose and Blue Sepharose. This enzyme catalyzes the release of ADP-ribose from mono(ADP-ribosyl) Gi. Its activity was enhanced by Ca2+ and inhibited by ADP-ribose. The presence of this enzyme in eukaryotic cells suggests that endogenous mono(ADP-ribosyl)ation of Gi is a reversible post-translational modification.

Inhibitors of poly(ADP-ribose) polymerase suppress nuclear fragmentation and apoptotic-body formation during apoptosis in HL-60 cells.

The effects of 3-aminobenzamide (3ABm) and benzamide (BAm), known specific inhibitors of poly(ADP-ribose) polymerase (PARP), on actinomycin D (Act D)-induced apoptosis in HL-60 cells were examined. These inhibitors had no appreciable effect on apoptotic DNA fragmentation, chromatin condensation or PARP restriction cleavage, but clearly inhibited morphological changes, especially nuclear fragmentation and apoptotic-body formation, in a dose-dependent manner. These results suggest that the synthesis of ADP-ribose polymers is not essential for the progression of apoptotic DNA fragmentation and chromatin condensation, but is required in the processes leading to nuclear fragmentation and the subsequent apoptotic-body formation during apoptosis in HL-60 cells.

Purification of a novel B cell growth and differentiation factor associated with lupus syndrome.

We have previously reported that KML1-7 cells cloned from a lupus-prone MRL/l mice produced a soluble factor that preferentially expanded anti-DNA antibody production across the H-2 barrier. We purified this factor, a 55-kDa protein that we termed nucleobindin (Nuc). Nuc showed not only induction of anti-ssDNA IgG antibody in cultures of B cells from MRL/l mice (greater than 16 weeks old), but also growth activity. Furthermore, antibodies against existing cytokines have so far not been shown to block Nuc activity on these B cells. In view of the fact that Nuc did not boost anti-ssDNA IgG antibody production in cultures of spleen cells of comparable age from MRL/n mice, which develop a mild form of lupus after the age of one year, Nuc may act on pre-activated B cells to help IgG anti-DNA antibody production. Taken together, Nuc is a new kind of growth and differentiation factor associated with lupus syndrome.

Induction of autoantibodies in normal mice by injection of nucleobindin and natural occurrence of antibodies against nucleobindin in autoimmune MRL/lpr/lpr mice.

Our previous works have shown that nucleobindin (Nuc) or recombinant (r) Nuc not only augments anti-DNA antibody production in vitro but also accelerates autoimmune response in vivo in MRL/+/+ (MRL/n) mice which are the substrain of autoimmune MRL/lpr/lpr (MRL/l) mice. To investigate whether rNuc can induce autoimmune response similarly in naive mice, we carried out intraperitoneal (i.p.) injection of rNuc (5 micrograms) without adjuvant into 8-week-old female BALB/c mice and continued injection twice a week for 12 weeks. About 5 weeks after the first injection, all the mice began to show IgG hypergammaglobulinemia (HG) followed by elevation of a number of autoantibodies of the IgG class such as anti-double-stranded (ds) DNA, anti-U1 ribonuclear protein (RNP), anti-ssB(La) and anti-Fc antibodies (RF), but not by anti-Sm antibodies. However, the IgG anti-dsDNA antibody response and histopathological changes in the kidney of these BALB/c mice were not so noticeable as those in MRL/n mice induced by rNuc in our previous experiment. In contrast, the IgG anti-rNuc antibody response of normal BALB/c mice induced by rNuc was stronger than that of MRL/n mice induced by rNuc. Since the titers of each autoantibody of BALB/c mice induced by rNuc were not always associated with the level of IgG HG, and either IgG HG or IgG autoantibodies could not be induced by control administration of extracts (5 micrograms) of Escherichia coli with or without harboring plasmid alone, polyclonal B cell activation (PBA) appeared not to be the mechanism of this autoimmunity.(ABSTRACT TRUNCATED AT 250 WORDS)

DNA fragmentation in ischemic core and penumbra in focal cerebral ischemia in rats.

Although apoptotic cell death has been suggested to be involved in ischemic injury of the brain, the precise mechanisms of ischemic neuronal cell death are unknown. Here, we examined the biochemical feature of apoptosis (i.e. DNA fragmentation) in male spontaneously hypertensive rats (5-7 months old) subjected to photothrombotic distal middle cerebral artery (MCA) occlusion. After MCA occlusion, the brain was cut in a cryostat to produce a standard coronal block and samples were dissected from the regions corresponding to the ischemic core, penumbra and contralateral control areas. Changes in cerebral blood flow (CBF) were monitored at 1 mm posterior and 2-4 mm lateral to the bregma by means of a laser-Doppler flowmetry. After MCA occlusion, CBF was decreased to 72+/-18 (+/-S.D.), 50+/-14, and 35+/-11% of the control values at 2, 3, and 4 mm from the midline, respectively. DNA fragmentation characteristics of apoptosis were examined in these samples by conventional and pulse-field gel electrophoresis. On the conventional gel electrophoresis, nucleosomal DNA fragmentation was detected in the penumbral zone at 6 h after MCA occlusion. Large DNA fragments of 50 and 20 kbp were detected in the penumbral zone and also in the ischemic core region at 3 h after distal MCA occlusion. The large DNA fragments seen on the pulse-field gel elecrophoresis were further degraded to small DNA fragments at 6 h after MCA occlusion in the penumbral zone but not in the core regions. The evolving DNA fragmentation was observed between 3 and 6 h after the onset of brain ischemia in the penumbra, suggesting that apoptosis may contribute to the development of ischemic infarction.

Inhibition of human immunodeficiency viral replication by tannins and related compounds.

Among 87 chemically defined tannins and related compounds, several hydrolyzable tannins, but not condensed tannins or other lower molecular weight polyphenols, significantly inhibited both the cytopathic effect of human immunodeficiency virus (HIV) and the expression of HIV antigen in human lymphotropic virus type I (HTLV-1)-positive MT-4 cells. The 50% effective concentrations (2.0-4.8 micrograms/ml) of the active compounds were 13- to 15-fold lower than their 50% cytotoxic concentrations. Their anti-HIV activity was demonstrated to be mediated, at least in part, by inhibition of HIV adsorption to the cells.

Inhibition of herpes simplex virus infection by tannins and related compounds.

Several chemically defined plant extracts were investigated for their antiviral action on herpes simplex virus (HSV-1, HSV-2)-infected African green monkey kidney cells and human adenocarcinoma cells, using a plaque formation assay. Among them, the monomeric hydrolyzable tannins, oligomeric ellagitannins and condensed tannins, having galloyl groups or hexahydroxydiphenoyl groups, had the most potent anti-HSV activity. Their 50% effective doses (0.03-0.1 microgram/ml) were by two-three orders of magnitude lower than their 50% cytotoxic doses (greater than 10 micrograms/ml). On the other hand, gallic acid, neutral polysaccharides, chemically modified (N,N-dimethylaminoethyl-, carboxymethyl-, and sulfated-) glucans, sialic acid-rich glycoproteins, and uronic acid-rich pine cone polysaccharide showed little or no activity. Using radiolabeled virus particles, we demonstrated that the anti-HSV effect of the tannins is due to inhibition of virus adsorption to the cells.

Acceptor proteins for (ADP-ribose)n in the HeLa S3 cell cycle.

The acceptor proteins for (ADP-ribose)n were investigated by using nuclei or chromosomes isolated from specific phases of the cell cycle of HeLa S3 cells. Analysis of HMG proteins and histone H1 by acetic acid/urea polyacrylamide gel electrophoresis demonstrated that the (ADP-ribosyl)n-ation of HMG 14 and 17 and histone H1 increased by 12- and 5-fold, respectively, in the metaphase chromosomes as compared with that in the G1 phase cell nuclei. The degree of (ADP-ribosyl)n-ation of these proteins in the S phase cell nuclei was as low as that in G1 phase cell nuclei. In the G2 phase cell nuclei, the degrees of (ADP-ribosyl)n-ation of HMG 14 and 17 and histone H1 were about 5- and 2-fold greater, respectively, as compared with that in the G1 phase cell nuclei. The (ADP-ribosyl)n-ation of HMG 1 and 2 was constant through the cell cycle except for a slight decrease in the S phase. The data may imply that the (ADP-ribosyl)n-ation of HMG 14 and 17 and histone H1 is linked to chromatin structural changes in mitosis.

An NAD:cysteine ADP-ribosyltransferase is present in human erythrocytes.

A novel enzymatic activity, i.e., the catalysis of the formation of ADP-ribosylcysteine, was found in the cytosol of human erythrocytes. The NAD:cysteine ADP-ribosyltransferase was partially purified by sequential chromatographic steps on phenyl-Sepharose, phosphocellulose, and Sepharose CL-6B. The enzyme has an apparent molecular weight of 27,000 +/- 3,000, as determined by gel permeation. The formation of ADP-ribosylcysteine was associated with the stoichiometric release of nicotinamide from NAD. The enzyme was found to be highly specific toward cysteine and cysteine methyl ester as ADP-ribose acceptors. S-Benzoyl-L-cysteine, cystine, histidine, glutamic acid, arginine, arginine methyl ester, and agmatine were ineffective as acceptors for this enzyme.

ATP requirement for the processes of DNA replication in isolated HeLa cell nuclei.

The ATP requirement for two steps of DNA replication, the synthesis and subsequent joining of Okazaki fragments, was investigated by using isolated HeLa cell nuclei. Among adenine nucleotides tested, high levels of dATP and ADP stimulated DNA synthesis. In the presence of high levels of ATP, the addition of high levels of dATP or ADP resulted in about 70% inhibition of DNa synthesis. The optimal concentration of ATP for the stimulation of DNA synthesis varied depending on the magnesium ion concentration. When the molar ratio of magnesium ion to ATP was approximately 1, maximal stimulation was attained. Product analysis by sedimentation in an alkaline sucrose gradient revealed that both Okazaki fragments and high molecular weight DNA were synthesized in the presence of high levels of ATP, whereas in the case of dATP and ADP, little high molecular weight DNA was synthesized. The ability to synthesize high molecular weight DNA was restored to nuclei by adding low levels of ATP in the presence of high levels of ADP but not of dATP.