Self-organization of supramolecular helical dendrimers into complex electronic materials

The discovery of electrically conducting organic crystals and polymers has widened the range of potential optoelectronic materials, provided these exhibit sufficiently high charge carrier mobilities and are easy to make and process. Organic single crystals have high charge carrier mobilities but are usually impractical, whereas polymers have good processability but low mobilities. Liquid crystals exhibit mobilities approaching those of single crystals and are suitable for applications, but demanding fabrication and processing methods limit their use. Here we show that the self-assembly of fluorinated tapered dendrons can drive the formation of supramolecular liquid crystals with promising optoelectronic properties from a wide range of organic materials. We find that attaching conducting organic donor or acceptor groups to the apex of the dendrons leads to supramolecular nanometre-scale columns that contain in their cores pi-stacks of donors, acceptors or donor-acceptor complexes exhibiting high charge carrier mobilities. When we use functionalized dendrons and amorphous polymers carrying compatible side groups, these co-assemble so that the polymer is incorporated in the centre of the columns through donor-acceptor interactions and exhibits enhanced charge carrier mobilities. We anticipate that this simple and versatile strategy for producing conductive pi-stacks of aromatic groups, surrounded by helical dendrons, will lead to a new class of supramolecular materials suitable for electronic and optoelectronic applications.

Biocompatible surfactants for water-in-fluorocarbon emulsions

Drops of water-in-fluorocarbon emulsions have great potential for compartmentalizing both in vitro and in vivo biological systems; however, surfactants to stabilize such emulsions are scarce. Here we present a novel class of fluorosurfactants that we synthesize by coupling oligomeric perfluorinated polyethers (PFPE) with polyethyleneglycol (PEG). We demonstrate that these block copolymer surfactants stabilize water-in-fluorocarbon oil emulsions during all necessary steps of a drop-based experiment including drop formation, incubation, and reinjection into a second microfluidic device. Furthermore, we show that aqueous drops stabilized with these surfactants can be used for in vitro translation (IVT), as well as encapsulation and incubation of single cells. The compatability of this emulsion system with both biological systems and polydimethylsiloxane (PDMS) microfluidic devices makes these surfactants ideal for a broad range of high-throughput, drop-based applications.

Molecular ordering of the cell death pathway. Bcl-2 and Bcl-xL function upstream of the CED-3-like apoptotic proteases

Genetic analyses of Caenorhabditis elegans has identified three genes that function in the regulation of nematode cell death. Mammalian homologs of two of these genes, ced-9 and ced-3, have been identified and comprise proteins belonging to the Bcl-2 and ICE families, respectively. To date, it is unclear where the negative regulators, ced-9 and bcl-2, function relative to the death effectors, ced-3 and the mammalian ced-3 homologs, respectively. Here, the molecular order of the cell death pathway is defined. Our results establish that Bcl-2 and Bcl-xL function upstream of two members of the ICE/CED-3 family of cysteine proteases, Yama (CPP32/apopain) and ICE-LAP3 (Mch3).

RAIDD is a new 'death' adaptor molecule

The effector arm of the cell-death pathway is composed of cysteine proteases belonging to the ICE/CED-3 family. In metazoan cells these exist as inactive polypeptide precursors (zymogens), each composed of a prodomain, which is cleaved to activate the protease, and a large and small catalytic subunit. The coupling of these 'death' proteases to signalling pathways is probably mediated by adaptor molecules that contain protein-protein interaction motifs such as the death domain. Here we describe such an adaptor molecule, RAIDD, which has an unusual bipartite architecture comprising a carboxy-terminal death domain that binds to the homologous domain in RIP, a serine/threonine kinase component of the death pathway. The amino-terminal domain is surprisingly homologous with the sequence of the prodomain of two ICE/CED-3 family members, human ICH-1 (ref. 5) and Caenorhabditis elegans CED-3 (ref. 6). This similar region mediates the binding of RAIDD to ICH-1 and CED-3, serving as a direct link to the death proteases, indicating that the prodomain may, through homophilic interactions, determine the specificity of binding of ICE/CED-3 zymogens to regulatory adaptor molecules. Finally, alternations in the sequence of the N-terminal domain that are equivalent to inactivating mutations in the C. elegans ced-3 gene prevent homophilic binding, highlighting the potentially primordial nature of this interaction.

ICE-LAP3, a novel mammalian homologue of the Caenorhabditis elegans cell death protein Ced-3 is activated during Fas- and tumor necrosis factor-induced apoptosis

Members of the ICE/ced-3 gene family have been implicated as components of the cell death pathway. Based on similarities with the structural prototype interleukin-1 beta-converting enzyme (ICE), family members are synthesized as proenzymes that are proteolytically processed to form active heterodimeric enzymes. In this report, we describe a novel member of this growing gene family, ICE-LAP3, which is closely related to the death effector Yama/CPP32/Apopain. Pro-ICE-LAP3 is a 35-kDa protein localized to the cytoplasm and expressed in a variety of tissues and cell lines. Overexpression of a truncated version of ICE-LAP3 (missing the pro-domain) induces apoptosis in MCF7 breast carcinoma cells. Importantly, upon receipt of a death stimulus, endogenous ICE-LAP3 is processed to its subunit forms, suggesting a physiological role in cell death. This is the first report to demonstrate processing of a native ICE/ced-3 family member during execution of the death program and the first description of the subcellular localization of an ICE/ced-3 family member.

Solution structure of the RAIDD CARD and model for CARD/CARD interaction in caspase-2 and caspase-9 recruitment

Apoptosis requires recruitment of caspases by receptor-associated adaptors through homophilic interactions between the CARDs (caspase recruitment domains) of adaptor proteins and prodomains of caspases. We have solved the CARD structure of the RAIDD adaptor protein that recruits ICH-1/caspase-2. It consists of six tightly packed helices arranged in a topology homologous to the Fas death domain. The surface contains a basic and an acidic patch on opposite sides. This polarity is conserved in the ICH-1 CARD as indicated by homology modeling. Mutagenesis data suggest that these patches mediate CARD/CARD interaction between RAIDD and ICH-1. Subsequent modeling of the CARDs of Apaf-1 and caspase-9, as well as Ced-4 and Ced-3, showed that the basic/acidic surface polarity is highly conserved, suggesting a general mode for CARD/CARD interaction.

ICE-LAP6, a novel member of the ICE/Ced-3 gene family, is activated by the cytotoxic T cell protease granzyme B

Members of the ICE/Ced-3 gene family are likely effector components of the cell death machinery. Here, we characterize a novel member of this family designated ICE-LAP6. By phylogenetic analysis, ICE-LAP6 is classified into the Ced-3 subfamily which includes Ced-3, Yama/CPP32/apopain, Mch2, and ICE-LAP3/Mch3/CMH-1. Interestingly, ICE-LAP6 contains an active site QACGG pentapeptide, rather than the QACRG pentapeptide shared by other family members. Overexpression of ICE-LAP6 induces apoptosis in MCF7 breast carcinoma cells. More importantly, ICE-LAP6 is proteolytically processed into an active cysteine protease by granzyme B, an important component of cytotoxic T cell-mediated apoptosis. Once activated, ICE-LAP6 is able to cleave the death substrate poly(ADP-ribose) polymerase into signature apoptotic fragments.

Combinatorial signaling in the specification of unique cell fates

How multifunctional signals combine to specify unique cell fates during pattern formation is not well understood. Here, we demonstrate that together with the transcription factor Lozenge, the nuclear effectors of the EGFR and Notch signaling pathways directly regulate D-Pax2 transcription in cone cells of the Drosophila eye disc. Moreover, the specificity of D-Pax2 expression can be altered upon genetic manipulation of these inputs. Thus, a relatively small number of temporally and spatially controlled signals received by a set of pluripotent cells can create the unique combinations of activated transcription factors required to regulate target genes and ultimately specify distinct cell fates within this group. We expect that similar mechanisms may specify pattern formation in vertebrate developmental systems that involve intercellular communication.

SAG, a novel zinc RING finger protein that protects cells from apoptosis induced by redox agents

SAG (sensitive to apoptosis gene) was cloned as an inducible gene by 1,10-phenanthroline (OP), a redox-sensitive compound and an apoptosis inducer. SAG encodes a novel zinc RING finger protein that consists of 113 amino acids with a calculated molecular mass of 12.6 kDa. SAG is highly conserved during evolution, with identities of 70% between human and Caenorhabditis elegans sequences and 55% between human and yeast sequences. In human tissues, SAG is ubiquitously expressed at high levels in skeletal muscles, heart, and testis. SAG is localized in both the cytoplasm and the nucleus of cells, and its gene was mapped to chromosome 3q22-24. Bacterially expressed and purified human SAG binds to zinc and copper metal ions and prevents lipid peroxidation induced by copper or a free radical generator. When overexpressed in several human cell lines, SAG protects cells from apoptosis induced by redox agents (the metal chelator OP and zinc or copper metal ions). Mechanistically, SAG appears to inhibit and/or delay metal ion-induced cytochrome c release and caspase activation. Thus, SAG is a cellular protective molecule that appears to act as an antioxidant to inhibit apoptosis induced by metal ions and reactive oxygen species.

Anti-cancer activities of tea epigallocatechin-3-gallate in breast cancer patients under radiotherapy

The purpose of this study was to test the hypothesis that administration of epigallocatechin-3-gallate (EGCG), a polyphenol present in abundance in widely consumed tea, inhibits cell proliferation, invasion, and angiogenesis in breast cancer patients. EGCG in 400 mg capsules was orally administered three times daily to breast cancer patients undergoing treatment with radiotherapy. Parameters related to cell proliferation, invasion, and angiogenesis were analyzed while blood samples were collected at different time points to determine efficacy of the EGCG treatment. Compared to patients who received radiotherapy alone, those given radiotherapy plus EGCG for an extended time period (two to eight weeks) showed significantly lower serum levels of vascular endothelial growth factor (VEGF), hepatocyte growth factor (HGF), and reduced activation of metalloproteinase-9 and metalloproteinase-2 (MMP9/MMP2). Addition of sera obtained from patients treated with combination of radiotherapy and EGCG feeding for 2-8 weeks to in vitro cultures of highly-metastatic human MDA-MB-231 breast cancer cells resulted in the following significant changes: (1) suppression of cell proliferation and invasion; (2) arrest of cell cycles at the G0/G1 phase; (3) reduction of activation of MMP9/MMP2, expressions of Bcl-2/Bax, c-Met receptor, NF-κB, and the phosphorylation of Akt. MDA-MB-231 cells exposed to 5-10 µM EGCG also showed significant augmentation of the apoptosis inducing effects of γ-radiation, concomitant with reduced NF-κB protein level and AKT phosphorylation. These results provide hitherto unreported evidence that EGCG potentiated efficacy of radiotherapy in breast cancer patients, and raise the possibility that this tea polyphenol has potential to be a therapeutic adjuvant against human metastatic breast cancer.

The Ret receptor protein tyrosine kinase associates with the SH2-containing adapter protein Grb10

Ret is a receptor protein tyrosine kinase that has been implicated in the development of the enteric nervous, endocrine, and renal systems. Mutations associated with multiple endocrine neoplasia types 2A and 2B (MEN 2A and 2B) have been shown to activate the intrinsic kinase and transforming ability of ret (Santoro, M., Carlomagno, F., Romano, A., Bottaro, D. P., Dathan, N. A., Grieco, M., Fusco, A., Vecchio, G., Matoskova, B., Kraus, M. H., and Paolo DiFiore, P. (1995) Science 267, 381-383). Using the cytoplasmic domain of Ret as bait in a yeast two-hybrid screen of a mouse embryonic library, it was discovered that the src homology 2 (SH2) domain containing protein Grb10 bound Ret. Grb10 belongs to an emerging family of SH2 containing adapter proteins, the prototypical member being Grb7. Using glutathione S-transferase fusion proteins, it was demonstrated that the SH2 domain of Grb10 specifically interacted with Ret. Additionally, using an EGFR/Ret chimera, it was shown that Grb10 bound Ret in an activation dependent manner in vivo. This is the first description of a receptor protein tyrosine kinase that utilizes Grb10 as a signaling intermediate.

Characterization of a novel Src-like adapter protein that associates with the Eck receptor tyrosine kinase

The Eph family of receptor protein tyrosine kinases (RPTKs) is the largest family of RPTKs. The signal transduction pathways initiated by this family have only recently begun to be explored. Using a yeast two-hybrid screen to identify molecules that interact with the cytoplasmic domain of Eck, it was previously shown that activated Eck RPTK bound to and stimulated phosphatidylinositol 3-kinase (Pandey, A., Lazar, D.F., Saltiel, A. R., and Dixit, V.M. (1994) J. Biol. Chem. 269, 30154-30157). Also isolated from this same screen was a novel protein containing SH3 and SH2 adapter modules that had striking homology to those found in the Src family of non-receptor tyrosine kinases. However, unlike other Src family members, it lacked a catalytic tyrosine kinase domain. Hence, this protein was designated SLAP for Src-like adapter protein. Using glutathione S-transferase fusion Proteins, it was demonstrated that SLAP bound to activated Eck receptor tyrosine kinase. Therefore, SLAP is a novel candidate downstream signaling intermediate and the first member of the Src family that resembles an adapter molecule.

Coumarins and bicoumarin from Ferula sumbul: anti-HIV activity and inhibition of cytokine release

The methanol extract of the dried roots of Ferula sumbul afforded two furanocoumarin esters, fesumtuorin A, B, one bicoumarin, fesumtuorin C, five spirobicoumarins, fesumtuorin D, E, F, G and H, along with nineteen known coumarins. Their structures were established on the basis of spectroscopic studies. Some of the isolated compounds showed anti-HIV activity and very weak inhibition of cytokine release.

Drosophila Lame duck, a novel member of the Gli superfamily, acts as a key regulator of myogenesis by controlling fusion-competent myoblast development

A hallmark of mature skeletal muscles is the presence of multinucleate muscle fibers. In Drosophila, the formation of muscle syncytia requires the cooperative participation of two types of myoblasts, founder cells and fusion-competent myoblasts. We show that a newly identified gene, lame duck (lmd), has an essential regulatory role in the specification and function of fusion-competent myoblasts. Embryos that lack lmd function show a loss of expression of two key differentiation and fusion genes, Mef2 and sticks-and-stones, in fusion-competent myoblasts and are completely devoid of multinucleate muscle fibers. By contrast, founder cells are specified and retain their capability to differentiate into mononucleate muscle cells. lmd encodes a novel member of the Gli superfamily of transcription factors and is expressed in fusion-competent myoblasts and their precursors in a Wingless- and Notch-dependent manner. The activity of the Lmd protein appears to be additionally controlled by its differential cytoplasmic versus nuclear localization. Results from an independent molecular screen for binding factors to a myoblast-specific Mef2 enhancer further demonstrate that Lmd is a direct transcriptional regulator of Mef2 in fusion-competent myoblasts.

Cytotoxic T-cell-derived granzyme B activates the apoptotic protease ICE-LAP3

Cytotoxic T lymphocytes (CTLs) and natural killers (NK) cells provide immune surveillance against viruses and neoplasms, and play a central role in the pathogenesis of autoimmune disease, AIDS and graft rejection. Thus, it is important to understand the precise molecular mechanism(s) whereby cytotoxic lymphocytes destroy susceptible target cells. Granule-mediated cytotoxicity requires a combination of both perforin and granzyme B. Perforin polymerizes to form transmembrane channels and presumably allows granzyme B access to target cell substrates, which until recently, were unknown. One clue to the identity of the physiological substrate(s) activated by granzyme B comes from its unusual specificity for cleaving synthetic substrates after aspartate residues. Members of the ICE/CED-3 family of cysteine proteases are prime candidates as they are important apoptotic effectors and are expressed as zymogens, which can be processed to form active heterodimeric enzymes after cleavage at specific aspartate residues. Previous studies have shown that granzyme B proteolytically activates the cell death effector Yama/CPP32/apopain (referred to here as Yama). Here we report that granzyme B also activates ICE-LAP3/Mch3/CMH-1 (referred to here as ICE-LAP3), which, along with Yama and Mch2, forms a subset of the ICE/CED-3 family of cysteine proteases most closely related to the Caenorhabditis elegans cell death gene, CED-3. Importantly, Jurkat T cells incubated with granzyme B and a sublytic concentration of perforin undergo apoptosis, which is preceded by the activation of endogenous ICE-LAP3. Thus, we propose that granzyme B mediates apoptosis by directly engaging the target cell's death effector machinery, which is probably composed of an arsenal of intracellular, CED-3-like cysteine proteases.

SAG/ROC/Rbx/Hrt, a zinc RING finger gene family: molecular cloning, biochemical properties, and biological functions

The RING (really interesting new gene) finger proteins containing a characteristic C3HC4 or C3H2C3 motif appear to act as E3 ubiquitin ligase and play important roles in many processes, including cell-cycle progression, oncogenesis, signal transduction, and development. This review is focused on SAG/ROC/Rbx/Hrt (sensitive to apoptosis gene/regulator of cullins/RING box protein), an evolutionarily conserved RING finger family of proteins that were cloned recently by several independent laboratories through differential display, yeast two-hybrid screening, or biochemical purification. SAG/ROC2/Rbx2/Hrt2 is expressed in multiple mouse adult tissues, as well as early embryos. In humans, both SAG and ROC1 are ubiquitously expressed at a very high level in heart, skeletal muscle, and testis. Expression of both SAG and ROC1 is induced by mitogenic stimulation. SAG is also induced by a redox agent in cultured cells, as well as in in vivo mouse brain upon ischemia/reperfusion. Structurally, SAG consists of four exons and three introns with at least one splicing variant and two pseudogenes. The SAG gene promoter is enriched with multiple transcription factor binding sites. Biochemically, SAG binds to RNA, has metal-ion binding/free radical scavenging activity, and is redox-sensitive. Most importantly, like ROC1, SAG/ROC2 binds to cullins and acts as an essential component of E3 ubiquitin ligase. Biologically, SAG is a growth-essential gene in yeast. In mammalian cells, SAG protects apoptosis mainly through inhibition of cytochrome c release/caspase activation, and promotes growth under serum deprivation at least in part by inhibiting p27 accumulation. Blocking SAG expression via antisense transfection inhibits tumor cell growth. Thus, SAG appears to be a valid drug target for anticancer therapy.

Quantitative analysis of the dendritic morphology of corticocortical projection neurons in the macaque monkey association cortex

The polymodal association areas of the primate cerebral cortex are heavily interconnected and play a crucial role in cognition. Area 46 of the prefrontal cortex in non-human primates receives direct inputs from several association areas, among them the cortical regions lining the superior temporal sulcus. We examined whether projection neurons providing such a corticocortical projection differ in their dendritic morphology from pyramidal neurons projecting locally within area 46. Specific sets of corticocortical projection neurons were identified by in vivo retrograde transport in young macaque monkeys. Full dendritic arbors of retrogradely labeled neurons were visualized in brain slices by targeted intracellular injection of Lucifer Yellow, and reconstructed three-dimensionally using computer-assisted morphometry. Total dendritic length, numbers of segments, numbers of spines, and spine density were analyzed in layer III pyramidal neurons forming long projections (from the superior temporal cortex to prefrontal area 46), as well as local projections (within area 46). Sholl analysis was also used to compare the complexity of these two groups of neurons. Our results demonstrate that long corticocortical projection neurons connecting the temporal and prefrontal cortex have longer, more complex dendritic arbors and more spines than pyramidal neurons projecting locally within area 46. The more complex dendritic arborization of such neurons is likely linked to their participation in cortical networks that require extensive convergence of multiple afferents at the cellular level.

An essential role for the Drosophila Pax2 homolog in the differentiation of adult sensory organs

The adult peripheral nervous system of Drosophila includes a complex array of mechanosensory organs (bristles) that cover much of the body surface of the fly. The four cells (shaft, socket, sheath, and neuron) which compose each of these organs adopt distinct fates as a result of cell-cell signaling via the Notch (N) pathway. However, the specific mechanisms by which these cells execute their conferred fates are not well understood. Here we show that D-Pax2, the Drosophila homolog of the vertebrate Pax2 gene, has an essential role in the differentiation of the shaft cell. In flies bearing strong loss-of-function mutations in the shaven function of D-Pax2, shaft structures specifically fail to develop. Consistent with this, we find that D-Pax2 protein is expressed in all cells of the bristle lineage during the mitotic (cell fate specification) phase of bristle development, but becomes sharply restricted to the shaft and sheath cells in the post-mitotic (differentiative) phase. Two lines of evidence described here indicate that D-Pax2 expression and function is at least in part downstream of cell fate specification mechanisms such as N signaling. First, we find that the lack of late D-Pax2 expression in the socket cell (the sister of the shaft cell) is controlled by N pathway activity; second, we find that loss of D-Pax2 function is epistatic to the socket-to-shaft cell fate transformation caused by reduced N signaling. Finally, we show that misexpression of D-Pax2 is sufficient to induce the production of ectopic shaft structures. From these results, we propose that D-Pax2 is a high-level transcriptional regulator of the shaft cell differentiation program, and acts downstream of the N signaling pathway as a specific link between cell fate determination and cell differentiation in the bristle lineage.

Immunosuppressive sesquiterpene alkaloids from Tripterygium wilfordii

Nine new sesquiterpene pyridine alkaloids [wilfornines A (1), B (2), C (3), D (4), E (5), F (8), and G (9); wilfordinines I (6) and J (7)] and six known compounds (10-15) were isolated from a clinically used extract (T(II)) of Tripterygium wilfordii. The structures of 1-9 were elucidated by spectroscopic and chemical methods. The inhibitory effects on cytokine production of 1-3 and several related compounds were evaluated. Compounds 10 and 14 showed significant inhibitory effects on cytokine production.

Yeast homolog of human SAG/ROC2/Rbx2/Hrt2 is essential for cell growth, but not for germination: chip profiling implicates its role in cell cycle regulation

In an attempt to understand the signaling pathway mediating redox-induced apoptosis, we cloned SAG, an evolutionarily conserved zinc RING finger gene that, when overexpressed, protects cells from apoptosis induced by redox agents. Here we report functional characterization of SAG by the use of yeast genetics approach. Targeted disruption of ySAG, yeast homolog of human SAG, and subsequent tetrad analysis revealed that ySAG is required for yeast viability. Complementation experiment showed that the lethal phenotype induced by the ySAG deletion is fully rescued by wildtype SAG, but not by several hSAG mutants. Complementation experiment has also confirmed that ySAG is essential for normal vegetative growth, rather than being required for sporulation. Furthermore, cell death induced by SAG deletion was accompanied by cell enlargement and abnormal cell cycle profiling with an increased DNA content. Importantly, SAG was found to be the second family member of Rbx (RING box protein) or ROC (Regulator of cullins) or Hrt that is a component of SCF E3 ubiquitin ligase. Indeed, like ROC1/Rbx1/Hrt1, SAG binds to Cul1 and SAG-Cul1 complex has ubiquitin ligase activity to promote poly-ubiquitination of E2/Cdc34. This ligase activity is required for complementation of death phenotype induced by ySAG disruption. Finally, chip profiling of the entire yeast genome revealed induction of several G1/S as well as G2/M checkpoint control genes upon SAG withdrawal. Thus, SAG appears to control cell cycle progression in yeast by promoting ubiquitination and degradation of cell cycle regulatory proteins. Oncogene (2000) 19, 2855 - 2866

Sesquiterpene alkaloids from Tripterygium hypoglaucum and Tripterygium wilfordii: a new class of potent anti-HIV agents

Five new sesquiterpene pyridine alkaloids [triptonines A (1) and B (2), and wilfordinines A (3), B (4), and C (5)] and two known compounds (peritassine A and hypoglaunine C) were isolated from Tripterygium hypoglaucum and a clinically used extract of Tripterygium wilfordii. The structures of 1-5 were elucidated by spectroscopic methods. The anti-HIV activity of 1, 2, and several related compounds was evaluated. Triptonine B (2) demonstrated potent anti-HIV activity with an EC(50) value of <0.10 microg/mL and an in vitro therapeutic index value of >1000.

Definitive support by transmission electron microscopy, electron diffraction, and electron density maps for the formation of a BCC lattice from poly[N-[3,4,5-tris(n-dodecan-1-yloxy)benzoyl]ethyleneimine]

Transmission electron microscopy (TEM), electron diffraction (ED), and electron density maps (EDM) experiments were carried out on a poly[N-[3,4,5-tris(n-dodecan-1-yloxy)benzoyl]ethyleneimine] [poly[(3,4,5)12G1-Oxz]] with a degree of polymerization (DP) of 20. All experiments confirmed the thermotropic body-centered cubic (BCC) Im3m lattice suggested previously by X-ray diffraction (XRD) experiments. The unit cell parameter determined by ED at 23 degrees C is a = 42.4 A, in good agreement with XRD results which show a = 42.6 A after quenching from 70 degrees C. EDM of the XRD results confirm that the supramolecular minidendrimer obtained from poly[(3,4,5)12G1-Oxz] adopts a spherical "inverse micellar-like" structure, with the polyethyleneimine backbone and the aromatic groups microsegregated and concentrated in the corners and in the center of the cubic unit cell. A space-filling continuum is realized by the n-alkyl groups that radiate out of the aromatic core of the spherical dendrimer. This manuscript is only the second example of complete structural analysis of a lattice generated from supramolecular objects and complements the previous example reported from our laboratory on the Pm3n lattice.

Characterization of Th17 and FoxP3(+) Treg Cells in Paediatric Psoriasis Patients

Psoriasis is one of the most common inflammatory skin conditions affecting both children and adults. Growing evidence indicates that T-helper 17 (Th17) cells and CD4(+) CD25(+) regulatory T (Treg) cells play an important role in the pathogenesis of psoriasis. However, the relationship between Th17 and Treg cells and their dynamic variations in paediatric psoriasis remain unclear. In this study, we found that both Th17 and FoxP3(+) Treg cells and the ratio of Th17 to Treg cell frequency in the peripheral circulation were increased in patients with paediatric psoriasis and were positively correlated with the disease severity. The function of Treg to suppress CD4(+) CD25(-) T cell proliferation and IFN-γ secretion was impaired during the onset of psoriasis. After disease remission, both the Th17 and Treg cell frequencies were decreased, and the suppressive function of the Treg cells was obviously restored. However, neither Treg cells from the disease onset nor those after remission can regulate IL-17 secretion by CD4(+) T cells. These findings will further our understanding of the associations between Th17 and Treg cells in paediatric psoriasis and their influence on disease severity.

Interleukin-8-positive neutrophils in psoriasis

We performed an immunohistochemical study to try to determine the cellular source of interleukin-8 (IL-8) in psoriatic skin lesions. IL-8 was positively stained in the vast majority of neutrophils but not in the mononuclear cells, macrophages, or keratinocytes. IL-8-positive neutrophils were seen both in Munro's microabcesses in cases of psoriasis vulgaris and in a small spongiform pustule and much larger macropustules of Kogoj in cases of pustular psoriasis. Some IL-8-positive neutrophils were observed in the upper dermis of pustular psoriasis. The staining was considered to be specific because it could be completely blocked by preabsorption with recombinant IL-8. In addition, stimulation of human neutrophils with lipopolysaccharide (LPS) or tumor necrosis factor-alpha (TNF-alpha) for 18 h induced IL-8 production in vitro. In our study, IL-8 was expressed in the neutrophils of psoriasis, suggesting that neutrophils are one of the sources of IL-8 in psoriasis. The expression of IL-8 and the influx of neutrophils led us to speculate that the IL-8 autocrine and/or paracrine system functions in the formation of the microabcesses and pustules in proriasis.