Scattered Golgi elements during microtubule disruption are initially enriched in trans-Golgi proteins

We have addressed the question of whether or not Golgi fragmentation, as exemplified by that occurring during drug-induced microtubule depolymerization, is accompanied by the separation of Golgi subcompartments one from another. Scattering kinetics of Golgi subcompartments during microtubule disassembly and reassembly following reversible nocodazole exposure was inferred from multimarker analysis of protein distribution. Stably expressed alpha-2,6-sialyltransferase and N-acetylglucosaminyltransferase-I (NAGT-I), both C-terminally tagged with the myc epitope, provided markers for the trans-Golgi/trans-Golgi network (TGN) and medial-Golgi, respectively, in Vero cells. Using immunogold labeling, the chimeric proteins were polarized within the Golgi stack. Total cellular distributions of recombinant proteins were assessed by immunofluorescence (anti-myc monoclonal antibody) with respect to the endogenous protein, beta-1,4-galactosyltransferase (GalT, trans-Golgi/TGN, polyclonal antibody). ERGIC-53 served as a marker for the intermediate compartment). In HeLa cells, distribution of endogenous GalT was compared with transfected rat alpha-mannosidase II (medial-Golgi, polyclonal antibody). After a 1-h nocodazole treatment, Vero alpha-2,6-sialyltransferase and GalT were found in scattered cytoplasmic patches that increased in number over time. Initially these structures were often negative for NAGT-I, but over a two- to threefold slower time course, NAGT-I colocalized with alpha-2,6-sialyltransferase and GalT. Scattered Golgi elements were located in proximity to ERGIC-53-positive structures. Similar trans-first scattering kinetics was seen with the HeLa GalT/alpha-mannosidase II pairing. Following nocodazole removal, all cisternal markers accumulated at the same rate in a juxtanuclear Golgi. Accumulation of cisternal proteins in scattered Golgi elements was not blocked by microinjected GTPgammaS at a concentration sufficient to inhibit secretory processes. Redistribution of Golgi proteins from endoplasmic reticulum to scattered structures following brefeldin A removal in the presence of nocodazole was not blocked by GTPgammaS. We conclude that Golgi subcompartments can separate one from the other. We discuss how direct trafficking of Golgi proteins from the TGN/trans-Golgi to endoplasmic reticulum may explain the observed trans-first scattering of Golgi transferases in response to microtubule depolymerization.

Intracerebral transplantation of adult mouse neural progenitor cells into the Niemann-Pick-A mouse leads to a marked decrease in lysosomal storage pathology

Niemann-Pick disease is caused by a genetic deficiency in acid sphingomyelinase (ASM) leading to the intracellular accumulation of sphingomyelin and cholesterol in lysosomes. In the present study, we evaluated the effects of direct intracerebral transplantation of neural progenitor cells (NPCs) on the brain storage pathology in the ASM knock-out (ASMKO) mouse model of Type A Niemann-Pick disease. NPCs derived from adult mouse brain were genetically modified to express human ASM (hASM) and were transplanted into multiple regions of the ASMKO mouse brain. Transplanted NPCs survived, migrated, and showed region-specific differentiation in the host brain up to 10 weeks after transplantation (the longest time point examined). In vitro, gene-modified NPCs expressed up to 10 times more and released five times more ASM activity into the culture media compared with nontransduced NPCs. In vivo, transplanted cells expressed hASM at levels that were barely detectable by immunostaining but were sufficient for uptake and cross-correction of host cells, leading to reversal of distended lysosomal pathology and regional clearance of sphingomyelin and cholesterol storage. Within the host brain, the area of correction closely overlapped with the distribution of the hASM-modified NPCs. No correction of pathology occurred in brain regions that received transplants of nontransduced NPCs. These results indicate that the presence of transduced NPCs releasing low levels of hASM within the ASMKO mouse brain is necessary and sufficient to reverse lysosomal storage pathology. Potentially, NPCs may serve as a useful gene transfer vehicle for the treatment of CNS pathology in other lysosomal storage diseases and neurodegenerative disorders.

Mast cells express IL-13R alpha 1: IL-13 promotes human lung mast cell proliferation and Fc epsilon RI expression

BACKGROUND

The Th2 cytokine interleukin (IL)-13 is implicated in the development of various allergic diseases including asthma. The IL-13 receptor, IL-13Ralpha1, is expressed on most leukocytes, except T-cells. Evidence to support IL-13Ralpha1 expression on mast cells is limited.

METHODS

We investigated: (i) IL-13Ralpha1 expression by human lung mast cells (HLMC); (ii) the number of IL-13Ralpha1+ bronchial submucosal mast cells in subjects with asthma and normal controls and (iii) the effect of IL-13 priming on HLMC expression of high-affinity IgE receptor (FcepsilonRI), stem cell factor receptor (CD117), histamine release, proliferation, and survival.

RESULTS

Human lung mast cell expressed IL-13Ralpha1 mRNA. IL-13Ralpha1 was highly expressed on the surface HLMC (82+/-9%). Bronchial submucosal mast cell IL-13Ralpha1 expression was higher in asthmatics (86+/-2%) than normal controls (78+/-2%; P=0.015). IL-13 priming for 30 min did not increase HLMC histamine release, in the presence or absence of SCF or in response to IgE/anti-IgE activation. IL-13 priming for 5 days upregulated HLMC FcepsilonRI expression (22% increase in fluorescent intensity; P=0.003), increased histamine release following IgE/anti-IgE activation by 56% (P=0.03) and increased proliferation by 50% (P=0.003) without affecting cell survival or CD117 expression. The IL-13 specific neutralizing antibody CAT-354 inhibited all IL-13 mediated effects.

CONCLUSION

Human lung mast cell express IL-13Ralpha1 and activation by IL-13 for 5 days increased FcepsilonRI expression and proliferation. Histamine release was not affected by short-term priming with IL-13, but was upregulated by priming for 5 days suggesting that this effect was mediated by the increased FcepsilonRI expression. These data support the view that targeting IL-13 may be beneficial in the treatment of asthma.

Genetic tuning of the novel avian influenza A(H7N9) virus during interspecies transmission, China, 2013

A novel avian influenza A(H7N9) virus causing human infection emerged in February 2013 in China. To elucidate the mechanism of interspecies transmission, we compared the signature amino acids of avian influenza A(H7N9) viruses from human and non-human hosts and analysed the reassortants of 146 influenza A(H7N9) viruses with full genome sequences. We propose a genetic tuning procedure with continuous amino acid substitutions and reassorting that mediates host adaptation and interspecies transmission. When the early influenza A(H7N9) virus, containing ancestor haemagglutinin (HA) and neuraminidase (NA) genes similar to A/Shanghai/05 virus, circulated in waterfowl and transmitted to terrestrial poultry, it acquired an NA stalk deletion at amino acid positions 69 to 73. Then, receptor binding preference was tuned to increase the affinity to human-like receptors through HA G186V and Q226L mutations in terrestrial poultry. Additional mammalian adaptations such as PB2 E627K were selected in humans. The continual reassortation between H7N9 and H9N2 viruses resulted in multiple genotypes for further host adaptation. When we analysed a potential association of mutations and reassortants with clinical outcome, only the PB2 E627K mutation slightly increased the case fatality rate. Genetic tuning may create opportunities for further adaptation of influenza A(H7N9) and its potential to cause a pandemic.

Enhanced electron transport in Nb-doped TiO2 nanoparticles via pressure-induced phase transitions

Anatase TiO2 is one of the most important energy materials but suffers from poor electrical conductivity. Nb doping has been considered as an effective way to improve its performance in the applications of photocatalysis, solar cells, Li batteries, and transparent conducting oxide films. Here, we report the further enhancement of electron transport in Nb-doped TiO2 nanoparticles via pressure-induced phase transitions. The phase transition behavior and influence of Nb doping in anatase Nb-TiO2 have been systematically investigated by in situ synchrotron X-ray diffraction and Raman spectroscopy. The bulk moduli are determined to be 179.5, 163.3, 148.3, and 139.0 GPa for 0, 2.5, 5.0, and 10.0 mol % Nb-doped TiO2, respectively. The Nb-concentration-dependent stiffness variation has been demonstrated: samples with higher Nb concentrations have lower stiffness. In situ resistance measurements reveal an increase of 40% in conductivity of quenched Nb-TiO2 in comparison to the pristine anatase phase. The pressure-induced conductivity evolution is discussed in detail in terms of the packing factor model, which provides direct evidence for the rationality of the correlation of packing factors with electron transport in semiconductors. Pressure-treated Nb-doped TiO2 with unique properties surpassing those in the anatase phase holds great promise for energy-related applications.

Rejection of disseminated metastases of colon carcinoma by synergism of IL-12 gene therapy and 4-1BB costimulation

In an orthotopic model of metastatic colon carcinoma established in the liver of mice, we have previously shown that the natural killer (NK) cells were the major effectors after intratumoral delivery of a recombinant adenovirus expressing the murine IL-12 gene. However, tumor cure and long-term survival were achieved only in a minority of animals. In the present study, we generated an effective antitumoral CD8(+ ) T-cell response by the combination of IL-12 gene therapy and systemic delivery of an agonistic monoclonal antibody against 4-1BB, a costimulatory molecule expressed on activated T cells. In the IL-12 plus anti-4-1BB combination treatment, the effective dose of IL-12 could even be reduced even up to 18-fold and still achieved a better efficacy than the maximal dose of either treatment alone. We further demonstrate that the innate and the adaptive antitumoral immune responses were synergistic, as animals bearing hepatic as well as multiple pulmonary metastases were quantitatively cured of their diseases after IL-12 gene therapy + anti-4-1BB combination treatment. Both NK and CD8(+) T cells were necessary in maintaining the long-term antitumor immunity, as depletion of either cell type in the cured animals abolished their abilities to reject tumor cells implanted at distal sites. These results indicate that synergism between innate and adaptive immune responses may be effectively exploited to treat patients with metastatic diseases.

The Cdc42 target ACK2 directly interacts with clathrin and influences clathrin assembly

The Ras-related GTP-binding protein Cdc42 has been implicated in a diversity of biological functions including the regulation of intracellular trafficking and endocytosis. While screening for Cdc42 targets that influence these activities, we identified the protein-tyrosine kinase ACK2 (for activated Cdc42-associated kinase 2) as a new binding partner for clathrin. ACK2 binds clathrin via a domain that is conserved among a number of other clathrin-binding proteins including the arrestins and AP-2. Overexpression of ACK2 in NIH3T3 cells results in an inhibition of transferrin receptor endocytosis because of a competition between ACK2 and AP-2 for clathrin. Activated Cdc42 weakens the interaction between ACK2 and clathrin and thus reverses the ACK2-mediated inhibition of endocytosis. Overexpression of ACK2 increases the amount of clathrin present in fractions enriched in clathrin-coated vesicles. Taken together, our data suggest that ACK2 may represent a novel clathrin-assembly protein and participate in the regulation of receptor-mediated endocytosis.

Hyperglycaemic hormones inhibit protein and mRNA synthesis in in vitro-incubated ovarian fragments of the marine shrimp Penaeus semisulcatus

The present work shows for the first time that peptides belonging to the Crustacean hyperglycaemic hormone family (CHH-family hormones) from Penaeus japonicus affect protein and mRNA synthesis in in vitro-incubated ovarian explant fragments removed from vitellogenic females of Penaeus semisulcatus. Reduced levels of protein synthesis, determined by TCA-precipitable 35S-labeled proteins, were found in the presence of crude sinus gland extracts from both P. semisulcatus and P. japonicus. A similar inhibitory effect compared to controls was found with each of the seven CHH-family peptides. Non-CHH-family peptides did not reduce protein synthesis. Crude sinus gland extracts prepared from P. semisulcatus were at least 20-fold more effective than sinus gland extracts of P. japonicus. The inhibition level was directly related to the concentration of the peptide in the incubation media, but its degree varied among the different tested peptides. The profile of proteins synthesized during in vitro incubation was analyzed using polyacrylamide gel electrophoresis under denatured and reduced conditions (SDS-PAGE), followed by autoradiography. Synthesis of several proteins was reduced, including proteins with electrophoretic mobility similar to that of vitellin. Immunoprecipitation with antiserum prepared against native ovarian vitellin confirmed the inhibitory effect of CHH-family peptides on vitellin synthesis. The crude sinus gland extract and CHH-family peptides also inhibited RNA synthesis, as determined by [3H]uridine incorporation into mRNA of ovarian fragments. It is concluded that in addition to their role in carbohydrate metabolism, CHH-family peptides may also influence ovarian physiology in crustaceans.

A stationary-phase protein of Escherichia coli that affects the mode of association between the trp repressor protein and operator-bearing DNA

Highly purified preparations of trp repressor (TrpR) protein derived from Escherichia coli strains that were engineered to overexpress this material were found to contain another protein, of 21 kDa. The second protein, designated WrbA [for tryptophan (W) repressor-binding protein] remained associated with its namesake through several sequential protein fractionation steps. The N-terminal amino acid sequence of the WrbA protein guided the design of two degenerate oligonucleotides that were used as probes in the cloning of the wrbA gene (198 codons). The WrbA protein, in purified form, was found by several criteria to enhance the formation and/or stability of noncovalent complexes between TrpR holorepressor and its primary operator targets. The formation of an operator-holorepressor-WrbA ternary complex was demonstrated by gel mobility-shift analysis. The WrbA protein alone does not interact with the trp operator. During the stationary phase, cells deficient in the WrbA protein were less efficient than wild type in their ability to repress the trp promoter. It is proposed that the WrbA protein functions as an accessory element in blocking TrpR-specific transcriptional processes that might be physiologically disadvantageous in the stationary phase of the bacterial life cycle.

Geranylgeranylation signals to the Hippo pathway for breast cancer cell proliferation and migration

Protein geranylgeranylation (GGylation) is an important biochemical process for many cellular signaling molecules. Previous studies have shown that GGylation is essential for cell survival in many types of cancer. However, the molecular mechanism mediating the cell survival effect remains elusive. In this report, we show that the Hippo pathway mediates GGylation-dependent cell proliferation and migration in breast cancer cells. Blockade of GGylation enhanced phosphorylation of Mst1/2 and Lats1, and inhibited YAP and TAZ activity and the Hippo-YAP/TAZ pathway-dependent transcription. The effect of GGylation blockade on inhibition of breast cancer cell proliferation and migration is dependent on the Hippo-YAP/TAZ signaling, in which YAP appears to regulate cell proliferation and TAZ to regulate cell migration. Furthermore, GGylation-dependent cell proliferation is correlated with the activity of YAP/TAZ in breast cancer cells. Finally, Gγ and RhoA are the GGylated proteins that may transduce GGylation signals to the Hippo-YAP/TAZ pathway. Taken together, our studies have demonstrated that the Hippo-YAP/TAZ pathway is essential for GGylation-dependent cancer cell proliferation and migration.

An ATF/CRE element mediates both EBNA2-dependent and EBNA2-independent activation of the Epstein-Barr virus LMP1 gene promoter

The Epstein-Barr virus (EBV) latent membrane protein 1 (LMP1) is a viral oncogene whose expression is regulated by both viral and cellular factors. EBV nuclear antigen 2 (EBNA2) is a potent transactivator of LMP1 expression in human B cells, and several EBNA2 response elements have been identified in the promoter regulatory sequence (LRS). We have previously shown that an activating transcription factor/cyclic AMP response element (ATF/CRE) site in LRS is involved in EBNA2 responsiveness. We now establish the importance of the ATF/CRE element by mutational analysis and show that both EBNA2-dependent activation and EBNA2-independent activation of the promoter occur via this site but are mediated by separate sets of factors. An electrophoretic mobility shift assay (EMSA) with specific antibodies showed that the ATF-1, CREB-1, ATF-2 and c-Jun factors bind to the site as ATF-1/CREB-1 and ATF-2/c-Jun heterodimers whereas the Sp1 and Sp3 factors bind to an adjacent Sp site. Overexpression of ATF-1 and CREB-1 in the cells by expression vectors demonstrated that homodimeric as well as heterodimeric forms of the factors transactivate the LMP1 promoter in an EBNA2-independent manner. The homodimers of ATF-2 and c-Jun did not significantly stimulate promoter activity. In contrast, the ATF-2/c-Jun heterodimer had only a minor stimulatory effect in the absence of EBNA2 but induced a strong transactivation of the LMP1 promoter when coexpressed with this protein. Evidence for a direct interaction between the ATF-2/c-Jun heterodimeric complex and EBNA2 was obtained by EMSA and coimmunoprecipitation experiments. Thus, our results suggest that EBNA2-induced transactivation via the ATF/CRE site occurs through a direct contact between EBNA2 and an ATF-2/c-Jun heterodimer. EBNA2-independent promoter activation via this site, on the other hand, is mediated by a heterodimeric complex between the ATF-1 and CREB-1 factors.

MGSA/GRO-mediated melanocyte transformation involves induction of Ras expression

The MGSA/GRO protein is endogenously expressed in almost 70% of the melanoma cell lines and tumors, but not in normal melanocytes. We have previously demonstrated that over-expression of human MGSA/GROalpha, beta or gamma in immortalized murine melanocytes (melan-a cells) enables these cells to form tumors in SCID and nude mice. To examine the possibility that the MGSA/GRO effect on melanocyte transformation requires expression of other genes, differential display was performed. One of the mRNA's identified in the screen as overexpressed in MGSA/GRO transformed melan-a clones was the newly described M-Ras or R-Ras3 gene, a member of the Ras gene superfamily. Over-expression of MGSA/GRO upregulates M-Ras expression at both the mRNA and protein levels, and this induction requires an intact glutamine-leucine-arginine (ELR)-motif in the MGSA/GRO protein. Western blot examination of Ras expression revealed that K- and N-Ras proteins are also elevated in MGSA/GRO-expressing melan-a clones, leading to an overall increase in the amount of activated Ras. MGSA/GRO-expressing melan-a clones exhibited enhanced AP-1 activity. The effects of MGSA/GRO on AP-1 activation could be mimicked by over-expression of wild-type M-Ras or a constitutively activated M-Ras mutant in control melan-a cells as monitored by an AP-1-luciferase reporter, while expression of a dominant negative M-Ras blocked AP-1-luciferase activity in MGSA/GRO-transformed melan-a clones. In the in vitro transformation assay, over-expression of M-Ras mimicked the effects of MGSA/GRO by inducing cellular transformation in control melan-a cells, while over-expression of dominant negative M-Ras in MGSA/GROalpha-expressing melan-a-6 cells blocked transformation. These data suggest that MGSA/GRO-mediated transformation requires Ras activation in melanocytes.

Antibodies to Schistosoma japonicum (Asian bloodfluke) paramyosin induced by nucleic acid vaccination

Nucleic acid vaccination by intramuscular or intradermal delivery of DNA plasmids encoding antigenic proteins has been shown to confer protection in experimental animals against viruses and unicellular protozoan parasites. However, this revolutionary approach has not been tested for induction of immunity to multicellular parasites, such as trematode worms. We report here, for the first time, that murine antibodies can be induced by intramuscular injection with plasmid DNA encoding fragments of Schistosoma japonicum paramyosin (Sj97), a 97 kDa molecule and a promising vaccine candidate in schistosomiasis. An additional construct containing the gene encoding full-length glutathione S-transferase (Sj26), another recognised anti-schistosome vaccine target, failed to raise detectable levels of specific antibody.

Asymmetric recognition of DNA local distortion. Structure-based functional studies of eukaryotic Msh2-Msh6

Crystal structures of bacterial MutS homodimers bound to mismatched DNA reveal asymmetric interactions of the two subunits with DNA. A phenylalanine and glutamate of one subunit make mismatched base-specific interactions, and residues of both subunits contact the DNA backbone surrounding the mismatched base, but asymmetrically. A number of amino acids in MutS that contact the DNA are conserved in the eukaryotic Msh2-Msh6 heterodimer. We report here that yeast strains with amino acids substituted for residues inferred to interact with the DNA backbone or mismatched base have elevated spontaneous mutation rates consistent with defective mismatch repair. Purified Msh2-Msh6 with substitutions in the conserved Phe(337) and Glu(339) in Msh6 thought to stack or hydrogen bond, respectively, with the mismatched base do have reduced DNA binding affinity but normal ATPase activity. Moreover, wild-type Msh2-Msh6 binds with lower affinity to mismatches with thymine replaced by difluorotoluene, which lacks the ability to hydrogen bond. The results suggest that yeast Msh2-Msh6 interacts asymmetrically with the DNA through base-specific stacking and hydrogen bonding interactions and backbone contacts. The importance of these contacts decreases with increasing distance from the mismatch, implying that interactions at and near the mismatch are important for binding in a kinked DNA conformation.

BRD4 regulates Nanog expression in mouse embryonic stem cells and preimplantation embryos

Bromodomain-containing protein 4 (BRD4) is an important epigenetic reader implicated in the pathogenesis of a number of different cancers and other diseases. Brd4-null mouse embryos die shortly after implantation and are compromised in their ability to maintain the inner cell mass, which gives rise to embryonic stem cells (ESCs). Here we report that BRD4 regulates expression of the pluripotency factor Nanog in mouse ESCs and preimplantation embryos, as well as in human ESCs and embryonic cancer stem cells. Inhibition of BRD4 function using a chemical inhibitor, small interfering RNAs, or a dominant-negative approach suppresses Nanog expression, and abolishes the self-renewal ability of ESCs. We also find that BRD4 associates with BRG1 (brahma-related gene 1, aka Smarca4 (SWI/SNF-related, matrix-associated, actin-dependent regulator of chromatin, subfamily a, member 4)), a key regulator of ESC self-renewal and pluripotency, in the Nanog regulatory regions to regulate Nanog expression. Our study identifies Nanog as a novel BRD4 target gene, providing new insights for the biological function of BRD4 in stem cells and mouse embryos. Knowledge gained from these non-cancerous systems will facilitate future investigations of how Brd4 dysfunction leads to cancers.

Virtual surgeries in patients with congenital heart disease: a multi-scale modelling test case

The objective of this work is to perform a virtual planning of surgical repairs in patients with congenital heart diseases--to test the predictive capability of a closed-loop multi-scale model. As a first step, we reproduced the pre-operative state of a specific patient with a univentricular circulation and a bidirectional cavopulmonary anastomosis (BCPA), starting from the patient's clinical data. Namely, by adopting a closed-loop multi-scale approach, the boundary conditions at the inlet and outlet sections of the three-dimensional model were automatically calculated by a lumped parameter network. Successively, we simulated three alternative surgical designs of the total cavopulmonary connection (TCPC). In particular, a T-junction of the venae cavae to the pulmonary arteries (T-TCPC), a design with an offset between the venae cavae (O-TCPC) and a Y-graft design (Y-TCPC) were compared. A multi-scale closed-loop model consisting of a lumped parameter network representing the whole circulation and a patient-specific three-dimensional finite volume model of the BCPA with detailed pulmonary anatomy was built. The three TCPC alternatives were investigated in terms of energetics and haemodynamics. Effects of exercise were also investigated. Results showed that the pre-operative caval flows should not be used as boundary conditions in post-operative simulations owing to changes in the flow waveforms post-operatively. The multi-scale approach is a possible solution to overcome this incongruence. Power losses of the Y-TCPC were lower than all other TCPC models both at rest and under exercise conditions and it distributed the inferior vena cava flow evenly to both lungs. Further work is needed to correlate results from these simulations with clinical outcomes.

When water meets iron at Earth's core–mantle boundary

Hydrous minerals in subducted crust can transport large amounts of water into Earth's deep mantle. Our laboratory experiments revealed the surprising pressure-induced chemistry that, when water meets iron at the core–mantle boundary, they react to form an interlayer with an extremely oxygen-rich form of iron, iron dioxide, together with iron hydride. Hydrogen in the layer will escape upon further heating and rise to the crust, sustaining the water cycle. With water supplied by the subducting slabs meeting the nearly inexhaustible iron source in the core, an oxygen-rich layer would cumulate and thicken, leading to major global consequences in our planet. The seismic signature of the D″ layer may echo the chemical complexity of this layer. Over the course of geological time, the enormous oxygen reservoir accumulating between the mantle and core may have eventually reached a critical eruption point. Very large-scale oxygen eruptions could possibly cause major activities in the mantle convection and leave evidence such as the rifting of supercontinents and the Great Oxidation Event.

Parameters important in fabricating enzyme electrodes using self-assembled monolayers of alkanethiols

The fabrication of enzyme electrodes using self-assembled monolayers (SAMs) has attracted considerable interest because of the spatial control over the enzyme immobilization. A model system of glucose oxidase covalently bound to a gold electrode modified with a SAM of 3-mercaptopropionic acid was investigated with regard to the effect of fabrication variables such as the surface topography of the underlying gold electrode, the conditions during covalent attachment of the enzyme and the buffer used. The resultant monolayer enzyme electrodes have excellent sensitivity and dynamic range which can easily be adjusted by controlling the amount of enzyme immobilized. The major drawback of such electrodes is the response which is limited by the kinetics of the enzyme rather than mass transport of substrates. Approaches to bringing such enzyme electrodes into the mass transport limiting regime by exploiting direct electron transfer between the enzyme and the electrode are outlined.

Syntheses, structures, and luminescence of novel lanthanide complexes of tripyridylamine, N,N,N',N'-tetra(2-pyridyl)-1,4-phenylenediamine and N,N,N',N'-tetra(2-pyridyl)biphenyl-4,4'-diamine

Two novel blue luminescent bridging ligands N,N,N',N'-tetra(2-pyridyl)-1,4-phenylenediamine (tppd) and N,N,N',N'-tetra(2-pyridyl)-1,1-biphenyl-4,4'-diamine (tpbpd) have been synthesized. Several novel lanthanide complexes containing 2,2',2"-tripyridylamine (2,2',2"-tpa), 2,2',3"-tpa, tppd, or tpbpd ligands have been synthesized and characterized structurally, which include Pr(hfa)3(2,2',2"-tpa), I, Ln(tmhd)3(2,2',3"-tpa), 2 (Ln = Dy, 2a; Eu, 2b; Tb, 2c; Sm, 2d), [Eu(tmhd)3][Pr(hfa)3](2,2',3"-tpa), 3, [Pr(hfa)3]2(tppd), 4, and [Ln(hfa)3]2(tpbpd), 5, where Ln = Pr (5a), Eu (5b), tmhd = 2,2,6,6-tetramethyl-3,5-heptanedionato, and hfa = hexafluoroacetylacetonate. The Dy(III), Eu(III), and Tb(III) complexes display a bright photoluminescence, which can be achieved by either a direct excitation process or an indirect excitation process. Compounds 2a-2d can be sublimed readily.

Effects of pulsed UV-light on peanut allergens in extracts and liquid peanut butter

Pulsed ultraviolet (PUV) light, a nonthermal technology, was used to treat both the peanut extracts and liquid peanut butter. The objective was to determine if such treatment would lead to a reduction in the allergenic properties of the peanut extract and butter. Peanut samples were PUV treated using a Xenon RS-3000C under the following conditions: 3 pulses/s, 14.6 cm from the central axis of the lamp, 4 min (extract) or 3 min (liquid peanut butter). After the treatment, the peanut samples were centrifuged and the supernatants analyzed by SDS-PAGE and competitive inhibition enzyme-linked immunosorbent assay (ciELISA). For comparison, boiling treatments were also performed. SDS-PAGE showed that while boiling treatment had little effect on the peanut allergens, PUV-light-treated samples displayed a reduced solubility or level of peanut allergens (63 kDa). Solubility of another allergen (18 to 20 kDa) was unaffected. Insoluble aggregates formed were responsible for the reduced level of allergens in PUV-light-treated samples. ciELISA showed that untreated samples exhibited an IgE binding 7-fold higher than the PUV-treated samples. It was concluded that PUV light was effective in reducing IgE binding of peanut extracts and liquid peanut butter. The current study provides an approach to the development of a possibly less allergenic peanut product. However, the reduction in actual allergenicity needs to be confirmed by clinical studies.