Urban eddy covariance measurements reveal significant missing NOx emissions in Central Europe

Nitrogen oxide (NO_x) pollution is emerging as a primary environmental concern across Europe. While some large European metropolitan areas are already in breach of EU safety limits for NO₂, this phenomenon does not seem to be only restricted to large industrialized areas anymore. Many smaller scale populated agglomerations including their surrounding rural areas are seeing frequent NO₂ concentration violations. The question of a quantitative understanding of different NO_x emission sources is therefore of immanent relevance for climate and air chemistry models as well as air pollution management and health. Here we report simultaneous eddy covariance flux measurements of NO_x, CO₂, CO and non methane volatile organic compound tracers in a city that might be considered representative for Central Europe and the greater Alpine region. Our data show that NO_x fluxes are largely at variance with modelled emission projections, suggesting an appreciable underestimation of the traffic related atmospheric NO_x input in Europe, comparable to the weekend-weekday effect, which locally changes ozone production rates by 40%.

A single-molecule approach to explore binding, uptake and transport of cancer cell targeting nanotubes

In the past decade carbon nanotubes (CNTs) have been widely studied as a potential drug-delivery system, especially with functionality for cellular targeting. Yet, little is known about the actual process of docking to cell receptors and transport dynamics after internalization. Here we performed single-particle studies of folic acid (FA) mediated CNT binding to human carcinoma cells and their transport inside the cytosol. In particular, we employed molecular recognition force spectroscopy, an atomic force microscopy based method, to visualize and quantify docking of FA functionalized CNTs to FA binding receptors in terms of binding probability and binding force. We then traced individual fluorescently labeled, FA functionalized CNTs after specific uptake, and created a dynamic 'roadmap' that clearly showed trajectories of directed diffusion and areas of nanotube confinement in the cytosol. Our results demonstrate the potential of a single-molecule approach for investigation of drug-delivery vehicles and their targeting capacity.

Mapping the intracellular distribution of carbon nanotubes after targeted delivery to carcinoma cells using confocal Raman imaging as a label-free technique

The uptake of carbon nanotubes (CNTs) by mammalian cells and their distribution within cells is being widely studied in recent years due to their increasing use for biomedical purposes. The two main imaging techniques used are confocal fluorescence microscopy and transmission electron microscopy (TEM). The former, however, requires labeling of the CNTs with fluorescent dyes, while the latter is a work-intensive technique that is unsuitable for in situ bio-imaging. Raman spectroscopy, on the other hand, presents a direct, straightforward and label-free alternative. Confocal Raman microscopy can be used to image the CNTs inside cells, exploiting the strong Raman signal connected to different vibrational modes of the nanotubes. In addition, cellular components, such as the endoplasmic reticulum and the nucleus, can be mapped. We first validate our method by showing that only when using the CNTs' G band for intracellular mapping accurate results can be obtained, as mapping of the radial breathing mode (RBM) only shows a small fraction of CNTs. We then take a closer look at the exact localization of the nanotubes inside cells after folate receptor-mediated endocytosis and show that, after 8-10 h incubation, the majority of CNTs are localized around the nucleus. In summary, Raman imaging has enormous potential for imaging CNTs inside cells, which is yet to be fully realized.

AFM imaging of functionalized carbon nanotubes on biological membranes

Multifunctional carbon nanotubes are promising for biomedical applications as their nano-size, together with their physical stability, gives access into the cell and various cellular compartments including the nucleus. However, the direct and label-free detection of carbon nanotube uptake into cells is a challenging task. The atomic force microscope (AFM) is capable of resolving details of cellular surfaces at the nanometer scale and thus allows following of the docking of carbon nanotubes to biological membranes. Here we present topographical AFM images of non-covalently functionalized single walled (SWNT) and double walled carbon nanotubes (DWNT) immobilized on different biological membranes, such as plasma membranes and nuclear envelopes, as well as on a monolayer of avidin molecules. We were able to visualize DWNT on the nuclear membrane while at the same time resolving individual nuclear pore complexes. Furthermore, we succeeded in localizing individual SWNT at the border of incubated cells and in identifying bundles of DWNT on cell surfaces by AFM imaging.

Valdecoxib does not interfere with the CYP2D6 substrate metoprolol

OBJECTIVE

We reported recently that celecoxib inhibits the metabolism of the cytochrome P450 (CYP)2D6 substrate metoprolol in volunteers. Valdecoxib, the active metabolite of parecoxib, has also been claimed to interfere with the metabolism of CYP2D6 substrates. However, little support for this contention is available despite the intensive use of parecoxib in the perioperative setting. Therefore, the objective of this study was to examine the effect of valdecoxib on the pharmacokinetics of the clinically relevant CYP2D6 substrate metoprolol.

METHODS

An open, randomized, 3-period crossover study was performed in 15 healthy male volunteers. Metoprolol (50 mg) was given in all 3 periods without, or following a 7-day pre-treatment with valdecoxib (20 mg, o.d.) or rofecoxib (25 mg, o.d.), to achieve steady state conditions of COX-2 inhibitors in Periods 2 and 3. In a small group of extensive metabolizers (EM/EM), short-term application of twice the dose was investigated.

RESULTS

No effect of valdecoxib (20 mg/d) or rofecoxib (25 mg/d) were detected on the area under the plasma concentration-time curve of metoprolol (323 +/- 333 to 324 +/- 296 or 309 +/- 256 microg x h/l) or at a higher dose. No significant changes of pharmacokinetic or pharmacodynamic parameters of metoprolol were apparent.

CONCLUSION

We conclude that, at therapeutic doses, valdecoxib and rofecoxib do not influence the CYP2D6 substrate metoprolol.

PCR-based DGGE fingerprinting and identification of methanogens detected in three different types of UASB granules

Methane is produced by various methanogenic bacteria present in upflow anaerobic sludge blanket (UASB) bioreactors. Methane can be used to predict and improve UASB bioreactor efficiency. The methanogen population in the granules can be influenced by the composition of the substrate. The aim of this study was to fingerprint and identify the methanogens present in three different types of UASB granules that had been used to treat winery, brewery and peach-lye canning effluents. This was done using polymerase chain reaction (PCR)-based denaturing gradient gel electrophoresis (DGGE) and DNA sequence analysis. The DGGE fingerprints obtained from the methanogen reference cultures of Methanosaeta concilii, Methanosaeta thermophila, Methanosarcina barkeri, Methanosarcina mazeii and Methanobacterium formicicum were compared to the DGGE profiles of the Archaea in the different granules. The positions of the DGGE bands that did not correspond well to the bands of the known species were sequenced and compared to sequences available on GenBank using the Blastn search option. The aligned DNA sequences were used to construct a phylogenetic tree. Based on the data obtained, a DGGE marker was constructed which was used to provide a quick method to identify the Archaeal members of the microbial consortium in UASB granules.

Glucocorticoid receptor homodimers and glucocorticoid-mineralocorticoid receptor heterodimers form in the cytoplasm through alternative dimerization interfaces

Steroid hormone receptors act to regulate specific gene transcription primarily as steroid-specific dimers bound to palindromic DNA response elements. DNA-dependent dimerization contacts mediated between the receptor DNA binding domains stabilize DNA binding. Additionally, some steroid receptors dimerize prior to their arrival on DNA through interactions mediated through the receptor ligand binding domain. In this report, we describe the steroid-induced homomeric interaction of the rat glucocorticoid receptor (GR) in solution in vivo. Our results demonstrate that GR interacts in solution at least as a dimer, and we have delimited this interaction to a novel interface within the hinge region of GR that appears to be both necessary and sufficient for direct binding. Strikingly, we also demonstrate an interaction between GR and the mineralocorticoid receptor in solution in vivo that is dependent on the ligand binding domain of GR alone and is separable from homodimerization of the glucocorticoid receptor. These results indicate that functional interactions between the glucocorticoid and mineralocorticoid receptors in activating specific gene transcription are probably more complex than has been previously appreciated.

D-site binding protein transactivation requires the proline- and acid-rich domain and involves the coactivator p300

The D-site binding protein (DBP) is a member of the proline- and acid-rich (PAR) domain subfamily of basic/leucine zipper proteins and is involved in transcriptional regulation in the liver. Deletion analysis of the DBP protein was carried out in an effort to define the function of the conserved PAR domain. Internal deletions of the protein, i.e. removing portions of the PAR domain, resulted in a substantial loss in transactivation of a high affinity DBP reporter construct when assayed in Hep G2 cells. These same sequences conferred significant transactivation to GAL4 DNA binding domain fusion proteins, indicating that this region acts as part of an independent activation domain comprised of sequences in both the amino terminus and in the PAR domain of DBP. The coexpression of full-length expression constructs for both DBP and hepatic leukemia factor resulted in a dramatic increase in activation mediated by the GAL4-DBP fusion proteins, suggesting the involvement of a regulated coactivator in this process. DBP transactivation appears to be a p300-dependent process, as a 12 S E1A expression construct disrupted DBP-mediated transactivation, and a p300 expression vector, but not a CREB binding protein vector, was able to restore DBP transactivation. These results suggest that the PAR domain is required for DBP activation, which occurs through a regulated, p300-dependent process.

An outbreak of congenital rubella in Chicago

After an outbreak of rubella in Chicago in 1978, an intensive survey of local health care personnel and hospital records identified 31 infants with congenital rubella syndrome (CRS). Rubella virus was isolated from 11 infants; rubella-IgM antibodies were demonstrated in seven infants; ten babies had persistent high rubella hemagglutination-inhibition (HI) titers. The incidence of CRS in Chicago between July 1978 and June 1979 was 48.9 per 100,000 live births. Mothers of babies with CRS frequently remembered a crash-illness during pregnancy (56%), were unmarried (74%), and were primigravidas (64%). No mother had received rubella vaccine. Review of prenatal rubella HI testing and follow-up immunization in one hospital showed that only eight (10.8%) of 74 seronegative women received rubella vaccine physicians need to place increased emphasis on detection and vaccination of susceptible adult women.