Ordered nanoporous arrays of carbon supporting high dispersions of platinum nanoparticles

Nanostructured carbon materials are potentially of great technological interest for the development of electronic, catalytic and hydrogen-storage systems. Here we describe a general strategy for the synthesis of highly ordered, rigid arrays of nanoporous carbon having uniform but tunable diameters (typically 6 nanometres inside and 9 nanometres outside). These structures are formed by using ordered mesoporous silicas as templates, the removal of which leaves a partially ordered graphitic framework. The resulting material supports a high dispersion of platinum nanoparticles, exceeding that of other common microporous carbon materials (such as carbon black, charcoal and activated carbon fibres). The platinum cluster diameter can be controlled to below 3 nanometres, and the high dispersion of these metal clusters gives rise to promising electrocatalytic activity for oxygen reduction, which could prove to be practically relevant for fuel-cell technologies. These nanomaterials can also be prepared in the form of free-standing films by using ordered silica films as the templates.

Locally resonant sonic materials

We have fabricated sonic crystals, based on the idea of localized resonant structures, that exhibit spectral gaps with a lattice constant two orders of magnitude smaller than the relevant wavelength. Disordered composites made from such localized resonant structures behave as a material with effective negative elastic constants and a total wave reflector within certain tunable sonic frequency ranges. A 2-centimeter slab of this composite material is shown to break the conventional mass-density law of sound transmission by one or more orders of magnitude at 400 hertz.

The lin-41 RBCC gene acts in the C. elegans heterochronic pathway between the let-7 regulatory RNA and the LIN-29 transcription factor

Null mutations in the C. elegans heterochronic gene lin-41 cause precocious expression of adult fates at larval stages. Increased lin-41 activity causes the opposite phenotype, reiteration of larval fates. let-7 mutations cause similar reiterated heterochronic phenotypes that are suppressed by lin-41 mutations, showing that lin-41 is negatively regulated by let-7. lin-41 negatively regulates the timing of LIN-29 adult specification transcription factor expression. lin-41 encodes an RBCC protein, and two elements in the lin-413'UTR are complementary to the 21 nucleotide let-7 regulatory RNA. A lin-41::GFP fusion gene is downregulated in the tissues affected by lin-41 at the time that the let-7 regulatory RNA is upregulated. We suggest that late larval activation of let-7 RNA expression downregulates LIN-41 to relieve inhibition of lin-29.

Structural basis for binding of Smac/DIABLO to the XIAP BIR3 domain

The inhibitor-of-apoptosis proteins (IAPs) regulate programmed cell death by inhibiting members of the caspase family of enzymes. Recently, a mammalian protein called Smac (also named DIABLO) was identified that binds to the IAPs and promotes caspase activation. Although undefined in the X-ray structure, the amino-terminal residues of Smac are critical for its function. To understand the structural basis for molecular recognition between Smac and the IAPs, we determined the solution structure of the BIR3 domain of X-linked IAP (XIAP) complexed with a functionally active nine-residue peptide derived from the N terminus of Smac. The peptide binds across the third beta-strand of the BIR3 domain in an extended conformation with only the first four residues contacting the protein. The complex is stabilized by four intermolecular hydrogen bonds, an electrostatic interaction involving the N terminus of the peptide, and several hydrophobic interactions. This structural information, along with the binding data from BIR3 and Smac peptide mutants reported here, should aid in the design of small molecules that may be used for the treatment of cancers that overexpress IAPs.

Protein kinase B/Akt participates in GLUT4 translocation by insulin in L6 myoblasts

L6 myoblasts stably transfected with a GLUT4 cDNA harboring an exofacial myc epitope tag (L6-GLUT4myc myoblasts) were used to study the role of protein kinase B alpha (PKBalpha)/Akt1 in the insulin-induced translocation of GLUT4 to the cell surface. Surface GLUT4myc was detected by immunofluorescent labeling of the myc epitope in nonpermeabilized cells. Insulin induced a marked translocation of GLUT4myc to the plasma membrane within 20 min. This was prevented by transient transfection of a dominant inhibitory construct of phosphatidylinositol (PI) 3-kinase (Deltap85alpha). Transiently transfected cells were identified by cotransfection of green fluorescent protein. A constitutively active PKBalpha, created by fusion of a viral Gag protein at its N terminus (GagPKB), increased the cell surface density of GLUT4myc compared to that of neighboring nontransfected cells. A kinase-inactive, phosphorylation-deficient PKBalpha/Akt1 construct with the mutations K179A (substitution of alanine for the lysine at position 179), T308A, and S473A (AAA-PKB) behaved as a dominant-negative inhibitor of insulin-dependent activation of cotransfected wild-type hemagglutinin (HA)-tagged PKB. Furthermore, AAA-PKB markedly inhibited the insulin-induced phosphorylation of cotransfected BAD, demonstrating inhibition of the endogenous PKB/Akt. Under the same conditions, AAA-PKB almost entirely blocked the insulin-dependent increase in surface GLUT4myc. PKBalpha with alanine substitutions T308A and S473A (AA-PKB) or K179A (A-PKB) alone was a less potent inhibitor of insulin-dependent activation of wild-type HA-PKB or GLUT4myc translocation than was AAA-PKB. Cotransfection of AAA-PKB with a fourfold DNA excess of HA-PKB rescued insulin-stimulated GLUT4myc translocation. AAA-PKB did not prevent actin bundling (membrane ruffling), though this response was PI 3-kinase dependent. Therefore, it is unlikely that AAA-PKB acted by inhibiting PI 3-kinase signaling. These results outline an important role for PKBalpha/Akt1 in the stimulation of glucose transport by insulin in muscle cells in culture.

A passive transfer model of the organ-specific autoimmune disease, bullous pemphigoid, using antibodies generated against the hemidesmosomal antigen, BP180

Subepidermal blistering associated with the human skin diseases bullous pemphigoid and herpes gestationis has been thought to be an IgG autoantibody-mediated process; however, previous attempts to demonstrate the pathogenicity of patient autoantibodies have been unsuccessful. An immunodominant and potentially pathogenic epitope associated with these blistering diseases has recently been mapped to the extracellular domain of a human epidermal antigen, BP180. Patient autoantibodies that react with this well-defined antigenic site failed to crossreact with the murine form of this autoantigen and thus could not be assayed for pathogenicity in a conventional passive transfer mouse model. As an alternative, rabbit polyclonal antibodies were generated against a segment of the murine BP180 protein homologous with the human BP180 autoantibody-reactive site and were passively transferred into neonatal BALB/c mice. The injected animals developed a subepidermal blistering disease that closely mimicked bullous pemphigoid and herpes gestationis at the clinical, histological, and immunological levels. Autoantibodies that recognize the human BP180 ectodomain are therefore likely to play an initiatory role in the pathogenesis of bullous pemphigoid and herpes gestationis.

Erythropoietin receptor mRNA expression in human endothelial cells

A previous report demonstrated that endothelial cells have erythropoietin receptors and respond to this hormone with enhanced proliferation. The present study demonstrates the existence of mRNA for erythropoietin receptor in human umbilical vein endothelial cells. We have reverse transcribed mRNA of endothelial cells and then used different PCR primers to amplify erythropoietin receptor target cDNA between exons 5 and 6 as well as 3-5 in addition to an internal standard DNA fragment. Correspondence of size as well as location of restriction endonuclease scission (Ava II) was used in comparing the amplified fragments of human endothelial cell erythropoietin receptor to those of two human erythroleukemia cell lines, OCIM1 and K562. No alpha- or gamma-globin mRNA was detected in endothelial cells but was readily demonstrable in OCIM1 cells. In addition, to determine whether the expression of human erythropoietin receptor on endothelial cells occurs in vivo, sections of umbilical cord and placenta were immunostained with antibodies against the extracellular portion of the receptor; the results showed strong positive staining of the vascular endothelium.

Loss of the imprinted IGF2/cation-independent mannose 6-phosphate receptor results in fetal overgrowth and perinatal lethality

Murine embryos that inherit a nonfunctional insulin-like growth factor-II/cation-independent mannose 6-phosphate receptor (Igf2r) gene from their fathers are viable and develop normally into adults. However, the majority of mice inheriting the same mutated allele from their mothers die around birth, as a consequence of major cardiac abnormalities. These mice do not express IGF2R in their tissues, are 25-30% larger than their normal siblings, have elevated levels of circulating IGF2 and IGF-binding proteins, and exhibit a slight kink in their tails. These results show that Igf2r is paternally imprinted and reveal that the receptor is crucial for regulating normal fetal growth, circulating levels of IGF2, and heart development.

Elevated CD38 antigen expression on CD8+ T cells is a stronger marker for the risk of chronic HIV disease progression to AIDS and death in the Multicenter AIDS Cohort Study than CD4+ cell count, soluble immune activation markers, or combinations of HLA-DR and CD38 expression

The prognostic value of several immunologic markers were compared in Los Angeles Multicenter AIDS Cohort Study (MACS) participants, most of whom had been infected with HIV for >8 years. Markers studied included CD4+ cell number, flow cytometric measurements of CD8+ cell expression of CD38 and HLA-DR antigens, and serum markers of immune activation including neopterin, beta2-microglobulin, soluble interleukin-2 receptor, soluble CD8, and soluble tumor necrosis factor receptor-alpha (TNF-alpha) type II. Cox proportional hazards models indicated that elevated CD38 on CD8, a flow cytometric measurement of CD8+ T-lymphocyte activation, was the most predictive marker of those studied for development of a clinical AIDS diagnosis and death. As compared with the reference group, who had CD38 on CD8 <2470 molecules per CD8+ cell and in whom 4 of 99 developed clinical AIDS within 3 years, participants with CD38 on CD8 between 2470 and 3899, 3900 and 7250, and >7250 had relative risks (and numbers developing AIDS within 3 years) of 5.0 (15 of 81), 12.3 (24 of 60), and 41.4 (36 of 49), respectively. The strong prognostic value of CD38 on CD8 measurements and the fundamental importance of chronic immune activation in the pathogenesis of HIV disease suggests that this marker might have utility in the clinical management of HIV-infected persons.

The evolution of H5N1 influenza viruses in ducks in southern China

The pathogenicity of avian H5N1 influenza viruses to mammals has been evolving since the mid-1980s. Here, we demonstrate that H5N1 influenza viruses, isolated from apparently healthy domestic ducks in mainland China from 1999 through 2002, were becoming progressively more pathogenic for mammals, and we present a hypothesis explaining the mechanism of this evolutionary direction. Twenty-one viruses isolated from apparently healthy ducks in southern China from 1999 through 2002 were confirmed to be H5N1 subtype influenza A viruses. These isolates are antigenically similar to A/Goose/Guangdong/1/96 (H5N1) virus, which was the source of the 1997 Hong Kong "bird flu" hemagglutinin gene, and all are highly pathogenic in chickens. The viruses form four pathotypes on the basis of their replication and lethality in mice. There is a clear temporal pattern in the progressively increasing pathogenicity of these isolates in the mammalian model. Five of six H5N1 isolates tested replicated in inoculated ducks and were shed from trachea or cloaca, but none caused disease signs or death. Phylogenetic analysis of the full genome indicated that most of the viruses are reassortants containing the A/Goose/Guangdong/1/96-like hemagglutinin gene and the other genes from unknown Eurasian avian influenza viruses. This study is a characterization of the H5N1 avian influenza viruses recently circulating in ducks in mainland China. Our findings suggest that immediate action is needed to prevent the transmission of highly pathogenic avian influenza viruses from the apparently healthy ducks into chickens or mammalian hosts.

Correlation between transcriptome and interactome mapping data from Saccharomyces cerevisiae

Genomic and proteomic approaches can provide hypotheses concerning function for the large number of genes predicted from genome sequences. Because of the artificial nature of the assays, however, the information from these high-throughput approaches should be considered with caution. Although it is possible that more meaningful hypotheses could be formulated by integrating the data from various functional genomic and proteomic projects, it has yet to be seen to what extent the data can be correlated and how such integration can be achieved. We developed a 'transcriptome-interactome correlation mapping' strategy to compare the interactions between proteins encoded by genes that belong to common expression-profiling clusters with those between proteins encoded by genes that belong to different clusters. Using this strategy with currently available data sets for Saccharomyces cerevisiae, we provide the first global evidence that genes with similar expression profiles are more likely to encode interacting proteins. We show how this correlation between transcriptome and interactome data can be used to improve the quality of hypotheses based on the information from both approaches. The strategy described here may help to integrate other functional genomic and proteomic data, both in yeast and in higher organisms.

The distinct roles of TRAF2 and RIP in IKK activation by TNF-R1: TRAF2 recruits IKK to TNF-R1 while RIP mediates IKK activation

The death domain kinase RIP and the TNF receptor-associated factor 2 (TRAF2) are essential effectors in TNF signaling. To understand the mechanism by which RIP and TRAF2 regulate TNF-induced activation of the transcription factor NF-kappaB, we investigated their respective roles in TNF-R1-mediated IKK activation using both RIP-/- and TRAF2-/- fibroblasts. We found that TNF-R1-mediated IKK activation requires both RIP and TRAF2 proteins. Although TRAF2 or RIP can be independently recruited to the TNF-R1 complex, neither one of them alone is capable of transducing the TNF signal that leads to IKK activation. Moreover, we demonstrated that IKK is recruited to the TNF-R1 complex through TRAF2 upon TNF treatment and that IKK activation requires the presence of RIP in the same complex.

The essential role of MEKK3 in TNF-induced NF-kappaB activation

Activation of IkappaB kinase (IKK) is the key step in stimulation of the transcription factor NF-kappaB, which regulates many genes in the inflammatory response pathway. The molecular mechanism that underlies IKK activation in response to tumor necrosis factor (TNF) is still unknown. Using mitogen-activated protein kinase kinase kinase 3 (MEKK3)-deficient fibroblast cells, we found that MEKK3 plays a critical role in TNF-induced NF-kappaB activation. We have shown that MEKK3 is required for IKK activation and functions downstream of receptor-interacting protein (RIP) and TNF receptor- associated factor 2. We have also shown that MEKK3 interacts with RIP and directly phosphorylates IKK. The kinase activity of MEKK3 is pivotal to its function and, therefore, MEKK3 links RIP and IKK in TNF-induced NF-kappaB activation.

Tas1r3, encoding a new candidate taste receptor, is allelic to the sweet responsiveness locus Sac

The ability to taste the sweetness of carbohydrate-rich foodstuffs has a critical role in the nutritional status of humans. Although several components of bitter transduction pathways have been identified, the receptors and other sweet transduction elements remain unknown. The Sac locus in mouse, mapped to the distal end of chromosome 4 (refs. 7-9), is the major determinant of differences between sweet-sensitive and -insensitive strains of mice in their responsiveness to saccharin, sucrose and other sweeteners. To identify the human Sac locus, we searched for candidate genes within a region of approximately one million base pairs of the sequenced human genome syntenous to the region of Sac in mouse. From this search, we identified a likely candidate: T1R3, a previously unknown G protein-coupled receptor (GPCR) and the only GPCR in this region. Mouse Tas1r3 (encoding T1r3) maps to within 20,000 bp of the marker closest to Sac (ref. 9) and, like human TAS1R3, is expressed selectively in taste receptor cells. By comparing the sequence of Tas1r3 from several independently derived strains of mice, we identified a specific polymorphism that assorts between taster and non-taster strains. According to models of its structure, T1r3 from non-tasters is predicted to have an extra amino-terminal glycosylation site that, if used, would interfere with dimerization.

Methadone and buprenorphine for the management of opioid dependence: a systematic review and economic evaluation

OBJECTIVES

To assess the clinical effectiveness and cost-effectiveness of buprenorphine maintenance therapy (BMT) and methadone maintenance therapy (MMT) for the management of opioid-dependent individuals.

DATA SOURCES

Major electronic databases were searched from inception to August 2005. Industry submissions to the National Institute for Health and Clinical Excellence were accessed.

REVIEW METHODS

The assessment of clinical effectiveness was based on a review of existing reviews plus an updated search for randomised controlled trials (RCTs). A decision tree with Monte Carlo simulation model was developed to assess the cost-effectiveness of BMT and MMT. Retention in treatment and opiate abuse parameters were sourced from the meta-analysis of RCTs directly comparing flexible MMT with flexible dose BMT. Utilities were derived from a panel representing a societal perspective.

RESULTS

Most of the included systematic reviews and RCTs were of moderate to good quality, and focused on short-term (up to 1-year follow-up) outcomes of retention in treatment and the level of opiate use (self-report or urinalysis). Most studies employed a trial design that compared a fixed-dose strategy (i.e. all individuals received a standard dose) of MMT or BMT and were conducted in predominantly young men who fulfilled criteria as opiate-dependent or heroin-dependent users, without significant co-morbidities. RCT meta-analyses have shown that a fixed dose of MMT or BMT has superior levels of retention in treatment and opiate use than placebo or no treatment, with higher fixed doses being more effective than lower fixed doses. There was evidence, primarily from non-randomised observational studies, that fixed-dose MMT reduces mortality, HIV risk behaviour and levels of crime compared with no therapy and one small RCT has shown the level of mortality with fixed-dose BMT to be significantly less than with placebo. Flexible dosing (i.e. individualised doses) of MMT and BMT is more reflective of real-world practice. Retention in treatment was superior for flexible MMT than flexible BMT dosing but there was no significant difference in opiate use. Indirect comparison of data from population cross-sectional studies suggests that mortality with BMT may be lower than that with MMT. A pooled RCT analysis showed no significant difference in serious adverse events with MMT compared with BMT. Although treatment modifier evidence was limited, adjunct psychosocial and contingency interventions (e.g. financial incentives for opiate-free urine samples) appeared to enhance the effects of both MMT and BMT. Also, MMT and BMT appear to be similarly effective whether delivered in a primary care or outpatient clinic setting. Although most of the included economic evaluations were considered to be of high quality, none used all of the appropriate parameters, effectiveness data, perspective and comparators required to make their results generalisable to the NHS context. One company (Schering-Plough) submitted cost-effectiveness evidence based on an economic model that had a 1-year time horizon and sourced data from a single RCT of flexible-dose MMT compared with flexible-dose BMT and utility values obtained from the literature; the results showed that for MMT vs no drug therapy, the incremental cost-effectiveness ratio (ICER) was pound 12,584/quality-adjusted life-year (QALY), for BMT versus no drug therapy, the ICER was pound 30,048/QALY and in a direct comparison, MMT was found to be slightly more effective and less costly than BMT. The assessment group model found for MMT versus no drug therapy that the ICER was pound 13,697/QALY, for BMT versus no drug therapy that the ICER was pound 26,429/QALY and, as with the industry model, in direct comparison, MMT was slightly more effective and less costly than BMT. When considering social costs, both MMT and BMT gave more health gain and were less costly than no drug treatment. These findings were robust to deterministic and probabilistic sensitivity analyses.

CONCLUSIONS

Both flexible-dose MMT and BMT are more clinically effective and more cost-effective than no drug therapy in dependent opiate users. In direct comparison, a flexible dosing strategy with MMT was found be somewhat more effective in maintaining individuals in treatment than flexible-dose BMT and therefore associated with a slightly higher health gain and lower costs. However, this needs to be balanced by the more recent experience of clinicians in the use of buprenorphine, the possible risk of higher mortality of MMT and individual opiate-dependent users' preferences. Future research should be directed towards the safety and effectiveness of MMT and BMT; potential safety concerns regarding methadone and buprenorphine, specifically mortality and key drug interactions; efficacy of substitution medications (in particular patient subgroups, such as within the criminal justice system, or within young people); and uncertainties in cost-effectiveness identified by current economic models.

The serpin alpha1-proteinase inhibitor is a critical substrate for gelatinase B/MMP-9 in vivo

We have identified the key protein substrate of gelatinase B/MMP-9 (GB) that is cleaved in vivo during dermal-epidermal separation triggered by antibodies to the hemidesmosomal protein BP180 (collagen XVII, BPAG2). Mice deficient in either GB or neutrophil elastase (NE) are resistant to blister formation in response to these antibodies in a mouse model of the autoimmune disease bullous pemphigoid. Disease develops upon complementation of GB -/- mice with NE -/- neutrophils or NE -/- mice with GB -/- neutrophils. Only NE degrades BP180 and produces dermal-epidermal separation in vivo and in culture. Instead, GB acts upstream to regulates NE activity by inactivating alpha1-proteinase inhibitor (alpha1-PI). Excess NE produces lesions in GB -/- mice without cleaving alpha1-PI. Excess alpha1-PI phenocopies GB and NE deficiency in wild-type mice.