Room-temperature ultraviolet nanowire nanolasers

Room-temperature ultraviolet lasing in semiconductor nanowire arrays has been demonstrated. The self-organized, <0001> oriented zinc oxide nanowires grown on sapphire substrates were synthesized with a simple vapor transport and condensation process. These wide band-gap semiconductor nanowires form natural laser cavities with diameters varying from 20 to 150 nanometers and lengths up to 10 micrometers. Under optical excitation, surface-emitting lasing action was observed at 385 nanometers, with an emission linewidth less than 0.3 nanometer. The chemical flexibility and the one-dimensionality of the nanowires make them ideal miniaturized laser light sources. These short-wavelength nanolasers could have myriad applications, including optical computing, information storage, and microanalysis.

Metabolic reprogramming in macrophage responses

Macrophages are critical mediators of tissue homeostasis, with the function of tissue development and repair, but also in defense against pathogens. Tumor-associated macrophages (TAMs) are considered as the main component in the tumor microenvironment and play an important role in tumor initiation, growth, invasion, and metastasis. Recently, metabolic studies have revealeded specific metabolic pathways in macrophages are tightly associated with their phenotype and function. Generally, pro-inflammatory macrophages (M1) rely mainly on glycolysis and exhibit impairment of the tricarboxylic acid (TCA) cycle and mitochondrial oxidative phosphorylation (OXPHOS), whereas anti-inflammatory macrophages (M2) are more dependent on mitochondrial OXPHOS. However, accumulating evidence suggests that macrophage metabolism is not as simple as previously thought. This review discusses recent advances in immunometabolism and describes how metabolism determines macrophage phenotype and function. In addition, we describe the metabolic characteristics of TAMs as well as their therapeutic implications. Finally, we discuss recent obstacles facing this area as well as promising directions for future study.

Patients with pseudomyxoma peritonei associated with disseminated peritoneal adenomucinosis have a significantly more favorable prognosis than patients with peritoneal mucinous carcinomatosis

BACKGROUND

Pseudomyxoma peritonei (PMP) is a poorly understood condition characterized by disseminated intraperitoneal mucinous tumors, often with mucinous ascites. The term PMP has been applied historically as a pathologic diagnostic term to both benign and malignant mucinous neoplasms that produce abundant extracellular mucin, resulting in a variable and poorly predictable prognosis. A recent study reported a pathologic classification that separated patients into prognostically distinct groups, but the follow-up was relatively short.

METHODS

Long-term follow-up data were analyzed for a previously reported series of 109 patients with PMP to examine the prognostic utility of a pathologic classification system that divided patients into three groups: disseminated peritoneal adenomucinosis (DPAM), peritoneal mucinous carcinomatosis (PMCA), and peritoneal mucinous carcinomatosis with intermediate or discordant features (PMCA-I/D). Patients whose tumors were classified 25 DPAM (n = 65 patients) had disease that was characterized by histologically bland to low-grade adenomatous mucinous epithelium associated with abundant extracellular mucin and fibrosis, often with an identifiable appendiceal mucinous adenoma that was the source of the peritoneal lesions. Patients whose tumors were classified 25 PMCA (n = 30 patients) had disease that was characterized by peritoneal lesions that displayed the cytologic and architectural features of mucinous carcinoma associated with extracellular mucin, often with an identifiable invasive mucinous adenocarcinoma of the gastrointestinal tract. Patients whose tumors were classified 25 PMCA-I (n = 11 patients) had peritoneal lesions that combined the features of DPAM and PMCA derived from well differentiated mucinous adenocarcinomas associated with adenomas. Patients whose tumors were classified 25 PMCA-D (n = 3 patients) had markedly atypical appendiceal adenomas associated with peritoneal lesions similar to PMCA.

RESULTS

Patients with DPAM had 5-year and 10-year survival rates of 75% and 68%, respectively (mean follow-up, 96 months; median follow-up, 104 months). Patients with PMCA and PMCA-I/D had a significantly worse prognosis, with 5-year and 10-year survival rates, respectively, of 50% and 21% for PMCA-I/D (mean follow-up, 58 months; median follow-up, 51 months) and 14% and 3% for PMCA (mean follow-up, 27 months; median follow-up, 16 months; P = 0.0001).

CONCLUSIONS

The term PMP should be used only as a clinical descriptor for patients who have the syndrome of mucinous ascites accompanied by a characteristic distribution of peritoneal mucinous tumors with the pathologic features of DPAM. DPAM should be used as a pathologic diagnostic term for patients with the bland peritoneal mucinous tumors associated with ruptured appendiceal mucinous adenomas and PMP. These patients should not be diagnosed with carcinoma, because they have disease that is distinct pathologically and prognostically from PMCA.

Interactions of bacterial cationic peptide antibiotics with outer and cytoplasmic membranes of Pseudomonas aeruginosa

Polymyxins B and E1 and gramicidin S are bacterium-derived cationic antimicrobial peptides. The polymyxins were more potent than gramicidin S against Pseudomonas aeruginosa, with MICs of 0.125 to 0. 25 and 8 microg/ml, respectively. These peptides differed in their affinities for binding to lipopolysaccharide, but all were able to permeabilize the outer membrane of wild-type P. aeruginosa PAO1 strain H103, suggesting differences in their mechanisms of self-promoted uptake. Gramicidin S caused rapid depolarization of the bacterial cytoplasmic membrane at concentrations at which no killing was observed within 30 min, whereas, conversely, the concentrations of the polymyxins that resulted in rapid killing resulted in minimal depolarization. These data indicate that the depolarization of the cytoplasmic membrane by these peptides did not correlate with bacterial cell lethality.

Stat recruitment by tyrosine-phosphorylated cytokine receptors: an ordered reversible affinity-driven process

Herein, we demonstrate that purified Stat1 binds to its tyrosine-phosphorylated docking site on the IFN gamma receptor alpha chain in a direct, specific, and reversible manner. Using surface plasmon resonance, we determine the affinity (KD = 137 nM) and specificity of the interaction and define the minimum affinity needed for receptor-mediated Stat1 activation. In addition, we quantitate the relative ability of purified Stat1 to interact with tyrosine-phosphorylated binding sites on other Stat proteins. Finally, we describe experiments that imply that the unidirectional release of activated Stat1 from the IFN gamma receptor reflects the preference of free tyrosine-phosphorylated Stat1 monomers to form high avidity reciprocal homodimers rather than reassociating with the receptor binding site. Our results demonstrate that IFN gamma-induced Stat1 activation is an ordered and affinity-driven process and we propose that this process may serve as a paradigm for Stat activation by other cytokine receptors.

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.

Soft x-ray scattering facility at the Advanced Light Source with real-time data processing and analysis

We present the development and characterization of a dedicated resonant soft x-ray scattering facility. Capable of operation over a wide energy range, the beamline and endstation are primarily used for scattering from soft matter systems around the carbon K-edge (∼285 eV). We describe the specialized design of the instrument and characteristics of the beamline. Operational characteristics of immediate interest to users such as polarization control, degree of higher harmonic spectral contamination, and detector noise are delineated. Of special interest is the development of a higher harmonic rejection system that improves the spectral purity of the x-ray beam. Special software and a user-friendly interface have been implemented to allow real-time data processing and preliminary data analysis simultaneous with data acquisition.

Synergistic interactions between mammalian antimicrobial defense peptides

A single animal can express several cationic antimicrobial peptides with different sequences and structures. We demonstrate that mammalian peptides from different structural classes frequently show synergy with each other and selectively show synergy with human lysozyme.

Cell cycle-regulated nuclear localization of MCM2 and MCM3, which are required for the initiation of DNA synthesis at chromosomal replication origins in yeast

MCM2 and MCM3 are two genetically interacting and structurally related proteins essential for growth in Saccharomyces cerevisiae. Mutants defective in these proteins affect the stability of minichromosomes in general, but the severity of the defect is dependent on the autonomously replicating sequence (ARS) that drives the replication of that plasmid. In this paper we show by two-dimensional gel electrophoresis that the initiation of DNA synthesis at chromosomal replication origins is also reduced in frequency in these mutants. We show further that the nuclear and subnuclear localizations of the MCM2 and MCM3 proteins are temporally regulated with respect to the cell cycle. These proteins enter the nucleus at the end of mitosis, persist there throughout G1 phase, and disappear from it at the beginning of S phase. Once inside the nucleus, a fraction of the MCM2 and MCM3 proteins becomes tightly associated with DNA. The association of MCM2 and MCM3 with chromatin presumably leads to the initiation of DNA synthesis, and their subsequent disappearance from the nucleus presumably prevents reinitiation of DNA synthesis at replication origins. This temporally and spatially restricted localization of MCM2 and MCM3 in the nucleus may serve to ensure that DNA replication occurs once and only once per cell cycle.

Glycation-induced inactivation and loss of antigenicity of catalase and superoxide dismutase

Oxidative mechanisms are thought to have a major role in several biological phenomena, including cataract formation and diabetic complications. Here we investigate the inactivation of catalase and superoxide dismutase, both powerful antioxidant enzymes, by sugars of different glycating abilities, and the loss of antigenicity that was monitored by the loss of activity after immunoprecipitation with monospecific antibodies. The antigenicity of non-glycated or glycated enzymes separated by affinity chromatography were determined by dot-blotting. Incubation with sugars resulted in a time-dependent inactivation of the enzymes. Ribose and fructose inactivated them more rapidly than glucose and glucose 6-phosphate. Glycation induced losses of antigenicity and inactivation simultaneously. The glycated enzymes had entirely lost their antigenicity compared with non-glycated enzyme. These results further support the idea that inactivation of enzyme and loss of antigenicity are simultaneous. This might occur in the pathogenesis of diabetic complications and aging.

Salt-resistant alpha-helical cationic antimicrobial peptides

Analogues based on the insect cecropin-bee melittin hybrid peptide (CEME) were studied and analyzed for activity and salt resistance. The new variants were designed to have an increase in amphipathic alpha-helical content (CP29 and CP26) and in overall positive charge (CP26). The alpha-helicity of these peptides was demonstrated by circular dichroism spectroscopy in the presence of liposomes. CP29 was shown to have activity against gram-negative bacteria that was similar to or better than those of the parent peptides, and CP26 had similar activity. CP29 had cytoplasmic membrane permeabilization activity, as assessed by the unmasking of cytoplasmic beta-galactosidase, similar to that of CEME and its more positively charged derivative named CEMA, whereas CP26 was substantially less effective. The activity of the peptides was not greatly attenuated by an uncoupler of membrane potential, carbonyl cyanide-m-chlorophenylhydrazone. The tryptophan residue in position 2 was shown to be necessary for interaction with cell membranes, as demonstrated by a complete lack of activity in the peptide CP208. Peptides CP29, CEME, and CEMA were resistant to antagonism by 0.1 to 0.3 M NaCl; however, CP26 was resistant to antagonism only by up to 160 mM NaCl. The peptides were generally more antagonized by 3 and 5 mM Mg2+ and by the polyanion alginate. It appeared that the positively charged C terminus in CP26 altered its ability to permeabilize the cytoplasmic membrane of Escherichia coli, although CP26 maintained its ability to kill gram-negative bacteria. These peptides are potential candidates for future therapeutic drugs.

Mcm2 and Mcm3, two proteins important for ARS activity, are related in structure and function

MCM2 and MCM3 are essential genes believed to play important roles in the initiation of DNA replication in Saccharomyces cerevisiae. Mutants defective in Mcm2 or Mcm3 are remarkably similar in phenotype. They both show an autonomously replicating sequence (ARS)-specific minichromosome maintenance defect, although their ARS specificities are not identical. In addition, these mutants exhibit a premitotic cell cycle arrest and an increase in chromosome loss and recombination. Genetic studies suggest that the two MCM gene products play interacting or complementary roles in DNA replication. Double mutants of mcm2-1 and mcm3-1 are inviable at the permissive growth temperature (23 degrees C) for each of the single mutants. Furthermore, overproduction of Mcm3 accentuates the deleterious effect of the mcm2-1 mutation, whereas overproduction of Mcm2 partially complements the mcm3-1 mutation. MCM2 encodes a protein of 890 amino acids containing a putative zinc-finger domain that is essential for Mcm2 function. Mcm2 shows striking homology to Mcm3 and three other proteins, Cdc46 of S. cerevisiae, and Nda4 and Cdc21 of Schizosaccharomyces pombe. The phenotypes of mutants defective in these proteins suggest that they belong to a protein family involved in the early steps of DNA replication.

Reduced voltage losses yield 10% efficient fullerene free organic solar cells with >1 V open circuit voltages

Optimization of the energy levels at the donor-acceptor interface of organic solar cells has driven their efficiencies to above 10%. However, further improvements towards efficiencies comparable with inorganic solar cells remain challenging because of high recombination losses, which empirically limit the open-circuit voltage (V_oc) to typically less than 1 V. Here we show that this empirical limit can be overcome using non-fullerene acceptors blended with the low band gap polymer PffBT4T-2DT leading to efficiencies approaching 10% (9.95%). We achieve V_oc up to 1.12 V, which corresponds to a loss of only E_g/q - V_oc = 0.5 ± 0.01 V between the optical bandgap E_g of the polymer and V_oc. This high V_oc is shown to be associated with the achievement of remarkably low non-geminate and non-radiative recombination losses in these devices. Suppression of non-radiative recombination implies high external electroluminescence quantum efficiencies which are orders of magnitude higher than those of equivalent devices employing fullerene acceptors. Using the balance between reduced recombination losses and good photocurrent generation efficiencies achieved experimentally as a baseline for simulations of the efficiency potential of organic solar cells, we estimate that efficiencies of up to 20% are achievable if band gaps and fill factors are further optimized.

piRNA-823 contributes to tumorigenesis by regulating de novo DNA methylation and angiogenesis in multiple myeloma

Aberrant DNA hypermethylation contributes to myelomagenesis by silencing tumor-suppressor genes. Recently, a few reports have suggested that a novel class of small non-coding RNAs, called Piwi-interacting RNAs (piRNAs), may be involved in the epigenetic regulation of cancer. In this study, for the first time we provided evidence that the expression of piRNA-823 was upregulated in multiple myeloma (MM) patients and cell lines, and positively correlated with clinical stage. Silencing piRNA-823 in MM cells induced deregulation of cell cycle regulators and apoptosis-related proteins expression, accompanied by inhibition of tumorigenicity in vitro and in vivo. Moreover, piRNA-823 was directly relevant to de novo DNA methyltransferases, DNMT3A and 3B, in primary CD138(+) MM cells. The inhibited expression of piRNA-823 in MM cells resulted in marked reduction of DNMT3A and 3B at both mRNA and protein levels, which in turn led to decrease in global DNA methylation and reexpression of methylation-silenced tumor suppressor, p16(INK4A). In addition, piRNA-823 abrogation in MM cells induced reduction of vascular endothelial growth factor secretion, with consequent decreased proangiogenic activity. Altogether, these data support an oncogenic role of piRNA-823 in the biology of MM, providing a rational for the development of piRNA-targeted therapeutic strategies in MM.

Biological properties of structurally related alpha-helical cationic antimicrobial peptides

A series of alpha-helical cationic antimicrobial peptide variants with small amino acid changes was designed. Alterations in the charge, hydrophobicity, or length of the variant peptides did not improve the antimicrobial activity, and there was no statistically significant correlation between any of these factors and the MIC for Pseudomonas aeruginosa, Escherichia coli, or Salmonella typhimurium. Individual peptides demonstrated synergy with conventional antibiotics against antibiotic-resistant strains of P. aeruginosa. The peptides varied considerably in the ability to bind E. coli O111:B4 lipopolysaccharide (LPS), and this correlated significantly with their antimicrobial activity and ability to block LPS-stimulated tumor necrosis factor and interleukin-6 production. In general, the peptides studied here demonstrated a broad range of activities, including antimicrobial, antiendotoxin, and enhancer activities.

A role for Cdk2 kinase in negatively regulating DNA replication during S phase of the cell cycle

Using cell-free extracts made from Xenopus eggs, we show that cdk2-cyclin E and A kinases play an important role in negatively regulating DNA replication. Specifically, we demonstrate that the cdk2 kinase concentration surrounding chromatin in extracts increases 200-fold once the chromatin is assembled into nuclei. Further, we find that if the cdk2-cyclin E or A concentration in egg cytosol is increased 16-fold before the addition of sperm chromatin, the chromatin fails to initiate DNA replication once assembled into nuclei. This demonstrates that cdk2-cyclin E or A can negatively regulate DNA replication. With respect to how this negative regulation occurs, we show that high levels of cdk2-cyclin E do not block the association of the protein complex ORC with sperm chromatin but do prevent association of MCM3, a protein essential for replication. Importantly, we find that MCM3 that is prebound to chromatin does not dissociate when cdk2-cyclin E levels are increased. Taken together our results strongly suggest that during the embryonic cell cycle, the low concentrations of cdk2-cyclin E present in the cytosol after mitosis and before nuclear formation allow proteins essential for potentiating DNA replication to bind to chromatin, and that the high concentration of cdk2-cyclin E within nuclei prevents MCM from reassociating with chromatin after replication. This situation could serve, in part, to limit DNA replication to a single round per cell cycle.

Replication focus-forming activity 1 and the Werner syndrome gene product

The initiation of DNA replication involves a minimum of four factors: a specific DNA sequence (origin), an initiator protein which binds to the origin, a helicase that unwinds the origin and a protein that binds single-stranded DNA that stabilizes the unwound origin. In eukaryotic cells, the origin recognition complex (ORC) is the initiator protein and replication protein A (RPA; ref. 3) is the single-stranded DNA-binding protein. However, the helicase has not been identified and the nature of origins remains elusive, except in the case of Saccharomyces cerevisiae. A unique feature of eukaryotic DNA replication is that it occurs at a few-hundred discrete foci. It has thus been proposed that a real origin must contain a specific DNA sequence and must be attached to replication foci. Using Xenopus laevis egg extracts, we have identified and purified a 170-kD protein, focus-forming activity 1 (FFA-1), which is required for the formation of replication foci. Here we report that FFA-1 has DNA-helicase activity. Moreover, it is a homologue of the human Werner syndrome gene product WRN, a protein associated with premature ageing in humans.

Alcohol and aldehyde dehydrogenase genotypes and drinking behavior of Chinese living in Shanghai

Alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH), the principal enzymes responsible for oxidative metabolism of ethanol, exist in multiple, genetically determined molecular forms. Widely different kinetic properties in some of these isozymes account for the individual differences in alcohol sensitivity. In this study we used the polymerase chain reaction/restriction fragment length polymorphism method to determine the genotypes of the ADH2 and ALDH2 loci of alcoholic and nonalcoholic Chinese living in Shanghai. We also investigated the subjects' drinking patterns by means of semistructured interviews. The alcoholics had significantly lower frequencies of the ADH2(2) and ALDH2(2) alleles than did the nonalcoholics, suggesting the inhibitory effects of these alleles for the development of alcoholism. In the nonalcoholic subjects, ADH2(2) had little, if any, effect, despite the significant effect of the ALDH2(2) allele in decreasing the alcohol consumption of the individual. Taken together, these results fit the proposed hypothesis for the development of alcoholism, i.e., drinking behavior is greatly influenced by the individual's genotypes of alcohol-metabolizing enzymes, and the risk of becoming alcoholic is proportionate with the ethanol consumption of the individual.

Results of treatment of 33 patients with peritoneal mesothelioma

BACKGROUND

Peritoneal mesothelioma is a rare peritoneal malignancy, representing approximately one-third of all mesotheliomas. It is regarded as a universally fatal cancer with few treatment options.

METHODS

Records of 33 patients with peritoneal mesothelioma were reviewed retrospectively. Demographic, clinical and quantitative prognostic indicators were evaluated and analysed statistically using survival as endpoint. Patients were treated by a uniform strategy involving cytoreductive surgery with peritonectomy procedures and perioperative intraperitoneal chemotherapy (cisplatin, doxorubicin).

RESULTS

There were ten women and 23 men; mean age was 53.0 years. Asbestos exposure was recorded in five patients and a family history of cancer in 13. Presentation was mainly abdominal distension and pain. Median survival was 31.0 months; overall projected survival at 3 years was 56 per cent. The most significant positive predictive factors of survival were: female sex (P= 0.003), low prior surgical score (P=0.002), completeness of cytoreduction (P=0.0002) and second-look surgery (P=0.019). The morbidity rate for this combined treatment was 33 per cent and the perioperative mortality rate was 3 per cent.

CONCLUSION

Although peritoneal mesothelioma is rare, progress in its management has occurred. Survival has been extended and selection factors by which patients may be allocated to aggressive management strategies have been defined.