Controlling spontaneous emission with metamaterials

We have observed, in metamaterial with hyperbolic dispersion (an array of silver nanowires in alumina membrane), a sixfold reduction of the emission lifetime of dye deposited onto the metamaterial's surface. This serves as evidence of an anomalously high density of photonic states in hyperbolic metamaterials, demonstrates the feasibility of an earlier-predicted single-photon gun, and paves the road for the use of metamaterials in quantum optics.

Critical role of cholesterol in bovine herpesvirus type 1 infection of MDBK cells

Cholesterol is involved in the life cycle of many viruses. Here, we examined the role of cholesterol for both viral envelope and target cell membrane for bovine herpesvirus type 1 (BoHV-1) infection. Cholesterol depletion by pretreatment of Madin-Darby bovine kidney (MDBK) cells with a cholesterol-sequestering drug methyl-beta-cyclodextrin (MbetaCD), inhibited the production of BoHV-1 in a dose-dependent manner. This inhibitory effect was partially reversed by cholesterol replenishment, indicating that the reduction was caused by cholesterol depletion. Cholesterol depletion at the post-entry stage only had a mild effect on the virus production. However, cell membrane cholesterol depletion did not reduce the virus attachment. In addition, treatment of BoHV-1 particles with MbetaCD also reduced the virus infectivity significantly and the effect was partially reversed by addition of exogenous cholesterol. Taken together, these data implicated that cell membrane cholesterol mainly contributed to BoHV-1 entry into MDBK cells and the viral envelope cholesterol was also essential for the virus infectivity.

Role of hypoxia-inducible factor-1 alpha in the regulation of plasminogen activator activity in rat knee joint chondrocytes

OBJECTIVE

To examine the effects of hypoxia-inducible factor-1alpha (HIF-1alpha) on the plasminogen activator's (PA) activity and on the expression of components of PA system in articular chondrocytes of rats.

METHODS

Chondrocytes from rat knee joint cartilage were cultured under normoxic, hypoxic, CoCl(2) simulated hypoxic, and interleukin-1beta (IL-1beta)-stimulated conditions. siRNA targeting HIF-1alpha was transfected into cells cultured under hypoxic, simulated hypoxic, and IL-1beta-stimulated conditions to silence HIF-1alpha. PA activity was determined by the hydrolysis of the chromogenic substrate H-D-Val-Leu-Lys-pNA (S-2251). The mRNA levels were measured by quantitative real-time reverse transcription polymerase chain reaction (RT-PCR). The intracellular/matrix-associate protein levels were detected by Western blot and the soluble protein levels were measured by enzyme linked immunosorbent assay (ELISA). Chromatin immunoprecipitation (CHIP) assay was performed to determine whether HIF-1alpha binds to the hypoxia response element (HRE) of target genes.

RESULTS

The enhancement of HIF-1alpha by CoCl(2) resulted in a decrease of PA activity, and the silence of HIF-1alpha by siRNA led to an increase of PA activity. The PA inhibitor-1 (PAI-1) mRNA and protein were increased by hypoxia or simulated hypoxia, which was reversed by the siRNA2-mediated silencing of HIF-1alpha. CHIP assay further confirmed that the induction of PAI-1 involved the binding of HIF-1alpha to the PAI-1 promoter, while the enhancement or silencing of HIF-1alpha did not affect the expression of urokinase type PA (uPA), tissue type PA (tPA) or uPA receptor (uPAR). Additionally, IL-1beta stimulated both HIF-1alpha and PAI-1 in articular chondrocytes, and the IL-1beta-mediated induction of PAI-1 was inhibited partly by HIF-1alpha silencing.

CONCLUSION

HIF-1alpha may inhibit the PA activity through stimulating the expression of PAI-1 in normal articular chondrocytes. The inhibition of HIF-1alpha in the PA activity of articular chondrocytes probably plays an important role in the maintenance of articular cartilage matrix.

[Isolation and identification of a Staphylococcus aureus small colony variants]

OBJECTIVE

Staphylococcus aureus small colony variants (S. aureus SCVs) could lead to persistent, recurrent infection with the characteristics of aminoglycosides antibiotics resistance, making them a big challenge for clinical diagnosis and therapy. We aimed at isolating and identifying isolates of S. aureus SCVs and providing the biological material of SCVs study in China.

METHODS

The combination assays of observing colony phenotype, identification of the species-specific gene nuc of S. aureus by PCR amplification and a series of biochemical tests were conducted on 104 clinical isolates originally isolated from human, cow and environment. The suspected isolates were confirmed as S. aureus SCVs by complementation assay with supplementation of menadione, thiamine, thymine and haemin.

RESULTS

One of the isolates from environment was identified as SCVs, named CDC54 with the species-specific gene nuc of Staphylococcus aureus (S. aureus) confirmed by PCR amplification, whose major phenotypes included smaller colony, decreased pigmentation, decreased coagulase, reduced fermentation of lactose, decreased haemolytic activity, increased resistance to aminoglycosides.

CONCLUSION

The CDC54 will play an important role in studying prevention, control and pathogenesis for S. aureus SCVs infection.

Controlling two-electron threshold dynamics in double photoionization of lithium by initial-state preparation

Double photoionization (DPI) and ionization-excitation (IE) of Li(2s) and Li(2p), state-prepared and aligned in a magneto-optical trap, were explored in a reaction microscope at the free-electron laser in Hamburg (FLASH). From 6 to 12 eV above threshold (homega = 85, 91 eV), total as well as differential DPI cross sections were observed to critically depend on the initial state and, in particular, on the alignment of the 2p orbital with respect to the VUV-light polarization, whereas no effect is seen for IE. The alignment sensitivity is traced back to dynamical electron correlation at threshold.

Cryptosporidium and cryptosporidiosis

Cryptosporidium is one of the most common enteric protozoan parasites of vertebrates with a wide host range that includes humans and domestic animals. It is a significant cause of diarrhoeal disease and an ubiquitous contaminant of water which serves as an excellent vehicle for transmission. A better understanding of the development and life cycle of Cryptosporidium, and new insights into its phylogenetic relationships, have illustrated the need to re-evaluate many aspects of the biology of Cryptosporidium. This has been reinforced by information obtained from the recent successful Cryptosporidium genome sequencing project, which has emphasised the uniqueness of this organism in terms of its parasite life style and evolutionary biology. This chapter provides an up to date review of the biology, biochemistry and host parasite relationships of Cryptosporidium.

Demonstration of a spaser-based nanolaser

One of the most rapidly growing areas of physics and nanotechnology focuses on plasmonic effects on the nanometre scale, with possible applications ranging from sensing and biomedicine to imaging and information technology. However, the full development of nanoplasmonics is hindered by the lack of devices that can generate coherent plasmonic fields. It has been proposed that in the same way as a laser generates stimulated emission of coherent photons, a 'spaser' could generate stimulated emission of surface plasmons (oscillations of free electrons in metallic nanostructures) in resonating metallic nanostructures adjacent to a gain medium. But attempts to realize a spaser face the challenge of absorption loss in metal, which is particularly strong at optical frequencies. The suggestion to compensate loss by optical gain in localized and propagating surface plasmons has been implemented recently and even allowed the amplification of propagating surface plasmons in open paths. Still, these experiments and the reported enhancement of the stimulated emission of dye molecules in the presence of metallic nanoparticles lack the feedback mechanism present in a spaser. Here we show that 44-nm-diameter nanoparticles with a gold core and dye-doped silica shell allow us to completely overcome the loss of localized surface plasmons by gain and realize a spaser. And in accord with the notion that only surface plasmon resonances are capable of squeezing optical frequency oscillations into a nanoscopic cavity to enable a true nanolaser, we show that outcoupling of surface plasmon oscillations to photonic modes at a wavelength of 531 nm makes our system the smallest nanolaser reported to date-and to our knowledge the first operating at visible wavelengths. We anticipate that now it has been realized experimentally, the spaser will advance our fundamental understanding of nanoplasmonics and the development of practical applications.

A multinational phase III randomized trial with or without consolidation chemotherapy using docetaxel and cisplatin after concurrent chemoradiation in inoperable stage III non-small cell lung cancer (CCheIN): Interim analysis

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Background: Currently, the recommended treatment for inoperable stage III non-small cell lung cancer (NSCLC) is concurrent chemoradiotherapy (CCRT). The efficacy of consolidation chemotherapy after CCRT needs to be confirmed. The aim of this phase III randomized trial is to determine the efficacy of consolidation chemotherapy with docetaxel (D) and cisplatin (P) following definitive CCRT with the same agents in stage III inoperable NSCLC. Herein we report the pre-planned interim analysis. Methods: Patients with inoperable stage III NSCLC were randomized to either CCRT alone (observation arm) or CCRT followed by consolidation chemotherapy (consolidation arm). N2 or N3 disease was confirmed by PET and/or pathology. CCRT with D (20 mg/m2) and P (20 mg/m2) was administered every week for 6 weeks with a total dose of 66 Gy of thoracic RT as 33 fractions. In the consolidation arm, patients were further treated with 3 cycles of D and P (35 mg/m2 each on day 1 and 8, every 3 weeks). The primary endpoint is time to progression (TTP). Total target number of patients is 458. Results: From Oct 2005 to Mar 2008, 233 patients were enrolled and 226 were randomized (observation 112; consolidation 114). Patients’ characteristics were similar in both arms. In the consolidation arm, 83 patients (73%) received consolidation chemotherapy, of whom 52 (45%) completed 3 planned cycles. Grade 3–4 neutropenia occurred in 5.4% of 203 consolidation cycles. Common non-hematologic toxicities of all grades during consolidation were anorexia (47%), nausea (37%), vomiting (16%), fatigue (35%) and esophagitis (31%). At the time of this analysis, there were 40 and 41 deaths in the observation and consolidation arms, respectively. Treatment-related mortality rates were similar. With a median follow-up of 28.2 months, the median TTP was 9.0 months in the observation arm and 13.9 months in the consolidation arm (P=0.19). Median overall survival was 20.7 and 21.2 months, respectively (P=0.49). Conclusions: This interim analysis suggests that consolidation chemotherapy with DP after CCRT with weekly DP is feasible and relatively well tolerated. Patient enrollment is ongoing.

No significant financial relationships to disclose.

CTLA4 gene polymorphisms are associated with chronic bronchitis

Chronic obstructive pulmonary disease (COPD) is characterised by chronic and progressive dyspnoea, cough and sputum production. T-lymphocytes may play a key role in the pathogenesis of COPD and chronic bronchitis. Cytotoxic T-lymphocyte antigen (CTLA) 4 is a potential candidate gene because it modulates T-cell activation. Genetic association between nine CTLA4 single nucleotide polymorphisms (SNPs) and chronic bronchitis was assessed in 606 pedigrees (1,896 individuals) from the International COPD Genetics Network (ICGN) population. We then replicated the associations in 342 COPD subjects with chronic bronchitis and 511 COPD subjects without chronic bronchitis from Bergen, Norway. Family-based association tests were used to analyse the ICGN cohort, and a logistic regression model was used for the Bergen cohort. Six CTLA4 SNPs were significantly associated with chronic bronchitis in the ICGN cohort (0.0079< or = p < or =0.0432), with three being replicated with the same directionality of association in the Bergen cohort (0.0325< or = p < or =0.0408). One of these replicated SNPs (rs231775) encodes the Thr to Ala substitution at amino acid position 17. Haplotype analyses supported the results of single SNP analyses. Thus, CTLA4 is likely to be a genetic determinant of chronic bronchitis among COPD cases.

Stimulated emission of surface plasmon polaritons

We have observed laserlike emission of surface plasmon polaritons (SPPs) decoupled to the glass prism in an attenuated total reflection setup. SPPs were excited by optically pumped molecules in a polymeric film deposited on the top of a silver film. Stimulated emission was characterized by a distinct threshold in the input-output dependence and narrowing of the emission spectrum. The observed stimulated emission and corresponding compensation of the metallic absorption loss by gain enables many applications of metamaterials and nanoplasmonic devices.

Repeat-based subtyping and grouping of Staphylococcus aureus from human infections and bovine mastitis using the R-domain of the clumping factor A gene

Staphylococcus aureus has become an emerging public health concern. Markers capable of differentiating separate host-specific lineages are needed for tracing strain sources. Thus, a coding variable number tandem repeat-based typing was explored in this study, based on R-domain of clumping factor A (clfA) gene. DNA from isolates and strains of human infections and bovine mastitis were amplified and sequenced. Sequences of clfA from published strains were also analyzed. Results indicate that except one with 36 copies, 44 of the 55 R-domains had repeat copies between 44 and 57, whereas the remaining 10 had 59.5 to 73 copies. Furthermore, human isolates were polymorphic, while mastitis isolates were clonal. Phylogenetic grouping assigned host-specific strains into respective clusters. The repeats were stable during passages in milk, nutrient broth, and invasion of mammary cells showing suitability for typing. Our data show that the R-domain can be useful for typing and grouping host-specific lineages. Moreover, existence of variant repeats in human strains and the dominance of a clonal motif in mastitis may imply that a specific selection has occurred in the mammary gland.

Elongation of surface plasmon polariton propagation length without gain

We have demonstrated that an addition of highly concentrated rhodamine 6G chloride dye to the PMMA film adjacent to a silver film can cause 30% elongation of the propagation length of surface Plasmon polaritons (SPPs). The possibility to elongate the SPP propagation length without optical gain opens a new technological dimension to low-loss nanoplasmonic and metamaterials.

[Identification of the 987P protein receptors for enterotoxigenic Escherichia coli]

The 987P fimbriae of enterotoxigenic Escherichia coli (ETEC) mediates adhesive interactions with brush border vesicle (BBV) of the intestinal epithelial cells from the neonatal piglets. By adhering to intestinal epithelial cells, producing localized multiplication, the 987P ETEC can progress to mucosal surface colonization and concomitant effective enterotoxin delivery. To identify the receptors for the 987P, BBV proteins from piglet intestinal villous epithelial cells were separated by SDS-PAGE and analyzed by Ligand blot, protein bands with a set of 32-35 kD recognized by the 987P fimbriae were subjected to in gel proteolysis with trypsin. The tryptic fragments were separated by microbore reversed phase HPLC(RP-HPLC), samples shown to contain one major peak by MALDI-MS were submitted to Edman sequencing, three peptides were sequenced successfully and the all of three peptides matched the sequences of human or porcine histone H1 proteins. Porcine histone H1 proteins isolated from both piglet intestinal epithelial cells and BBV demonstrated the same SDS-PAGE migration pattern and 987P-binding properties as the 987P-specific protein receptors from piglet intestinal brush border did. The above results indicated that the 987P protein receptors are piglet BBV-derived Histone H1 proteins.