Observational evidence for interhemispheric hydroxyl-radical parity.

The hydroxyl radical (OH) is a key oxidant involved in the removal of air pollutants and greenhouse gases from the atmosphere. The ratio of Northern Hemispheric to Southern Hemispheric (NH/SH) OH concentration is important for our understanding of emission estimates of atmospheric species such as nitrogen oxides and methane. It remains poorly constrained, however, with a range of estimates from 0.85 to 1.4 (refs 4, 7-10). Here we determine the NH/SH ratio of OH with the help of methyl chloroform data (a proxy for OH concentrations) and an atmospheric transport model that accurately describes interhemispheric transport and modelled emissions. We find that for the years 2004-2011 the model predicts an annual mean NH-SH gradient of methyl chloroform that is a tight linear function of the modelled NH/SH ratio in annual mean OH. We estimate a NH/SH OH ratio of 0.97 ± 0.12 during this time period by optimizing global total emissions and mean OH abundance to fit methyl chloroform data from two surface-measurement networks and aircraft campaigns. Our findings suggest that top-down emission estimates of reactive species such as nitrogen oxides in key emitting countries in the NH that are based on a NH/SH OH ratio larger than 1 may be overestimated.

Contribution of anthropogenic and natural sources to atmospheric methane variability.

Methane is an important greenhouse gas, and its atmospheric concentration has nearly tripled since pre-industrial times. The growth rate of atmospheric methane is determined by the balance between surface emissions and photochemical destruction by the hydroxyl radical, the major atmospheric oxidant. Remarkably, this growth rate has decreased markedly since the early 1990s, and the level of methane has remained relatively constant since 1999, leading to a downward revision of its projected influence on global temperatures. Large fluctuations in the growth rate of atmospheric methane are also observed from one year to the next, but their causes remain uncertain. Here we quantify the processes that controlled variations in methane emissions between 1984 and 2003 using an inversion model of atmospheric transport and chemistry. Our results indicate that wetland emissions dominated the inter-annual variability of methane sources, whereas fire emissions played a smaller role, except during the 1997-1998 El Niño event. These top-down estimates of changes in wetland and fire emissions are in good agreement with independent estimates based on remote sensing information and biogeochemical models. On longer timescales, our results show that the decrease in atmospheric methane growth during the 1990s was caused by a decline in anthropogenic emissions. Since 1999, however, they indicate that anthropogenic emissions of methane have risen again. The effect of this increase on the growth rate of atmospheric methane has been masked by a coincident decrease in wetland emissions, but atmospheric methane levels may increase in the near future if wetland emissions return to their mean 1990s levels.

Profiling cytotoxic microRNAs in pediatric and adult glioblastoma cells by high-content screening, identification, and validation of miR-1300.

MicroRNAs play an important role in the regulation of mRNA translation and have therapeutic potential in cancer and other diseases. To profile the landscape of microRNAs with significant cytotoxicity in the context of glioblastoma (GBM), we performed a high-throughput screen in adult and pediatric GBM cells using a synthetic oligonucleotide library representing all known human microRNAs. Bioinformatics analysis was used to refine this list and the top seven microRNAs were validated in a larger panel of GBM cells using state-of-the-art in vitro assays. The cytotoxic effect of our most relevant candidate was assessed in a preclinical model. Our screen identified ~100 significantly cytotoxic microRNAs with 70% concordance between cell lines. MicroRNA-1300 (miR-1300) was the most potent and robust candidate. We observed a striking binucleated phenotype in miR-1300 transfected cells due to cytokinesis failure followed by apoptosis. This was also observed in two stem-like patient-derived cultures. We identified the physiological role of miR-1300 as a regulator of endomitosis in megakaryocyte differentiation where blockade of cytokinesis is an essential step. In GBM cells, where miR-1300 is normally not expressed, the oncogene Epithelial Cell Transforming 2 (ECT2) was validated as a direct key target. ECT2 siRNA phenocopied the effects of miR-1300, and ECT2 overexpression led to rescue of miR-1300 induced binucleation. We showed that ectopic expression of miR-1300 led to decreased tumor growth in an orthotopic GBM model. Our screen provides a resource for the neuro-oncology community and identified miR-1300 as a novel regulator of endomitosis with translatable potential for therapeutic application.

Differential susceptibility to TRAIL of normal versus malignant human urothelial cells.

Comparing normal human urothelial (NHU) cells to a panel of six representative urothelial cell carcinoma (UCC)-derived cell lines, we showed that while TRAIL receptor expression patterns were similar, susceptibility to soluble recombinant crosslinked TRAIL fell into three categories. 4/6 carcinoma lines were sensitive, undergoing rapid and extensive death; NHU and 253J cells were partially resistant and HT1376 cells, like normal fibroblasts, were refractory. Both normal and malignant urothelial cells underwent apoptosis via the same caspase-8/9-mediated mechanism. Rapid receptor downregulation was a mechanism for evasion by some UCC cells. TRAIL resistance in malignant urothelial cells was partially dependent on FLIP(L) and was differentially mediated by p38(MAPK), whereas in normal cells, resistance was mediated by NF-kappaB. Importantly, extensive killing of UCC cells could be induced using noncrosslinked TRAIL after prolonged exposure, with no damage to their homologous, normal urothelial cell counterparts.

A novel mechanism of CD40-induced apoptosis of carcinoma cells involving TRAF3 and JNK/AP-1 activation.

Membrane-presented CD40 agonists can induce apoptosis in carcinoma, but not normal homologous epithelial cells, whereas soluble agonists are growth inhibitory but not proapoptotic unless protein synthesis is blocked. Here we demonstrate that membrane-presented CD40 ligand (CD154) (mCD40L), but not soluble agonists, triggers cell death in malignant human urothelial cells via a direct mechanism involving rapid upregulation of TNFR-associated factor (TRAF)3 protein, without concomitant upregulation of TRAF3 mRNA, followed by activation of the c-Jun N-terminal kinase (JNK)/activator protein-1 (AP-1) pathway and induction of the caspase-9/caspase-3-associated intrinsic apoptotic machinery. TRAF3 knockdown abrogated JNK/AP-1 activation and prevented CD40-mediated apoptosis, whereas restoration of CD40 expression in CD40-negative carcinoma cells restored apoptotic susceptibility via the TRAF3/AP-1-dependent mechanism. In normal human urothelial cells, mCD40L did not trigger apoptosis, but induced rapid downregulation of TRAF2 and 3, thereby paralleling the situation in B-lymphocytes. Thus, TRAF3 stabilization, JNK activation and caspase-9 induction define a novel pathway of CD40-mediated apoptosis in carcinoma cells.

Oncolytic reovirus enhances rituximab-mediated antibody-dependent cellular cytotoxicity against chronic lymphocytic leukaemia.

The naturally occurring oncolytic virus (OV), reovirus, replicates in cancer cells causing direct cytotoxicity, and can activate innate and adaptive immune responses to facilitate tumour clearance. Reovirus is safe, well tolerated and currently in clinical testing for the treatment of multiple myeloma, in combination with dexamethasone/carfilzomib. Activation of natural killer (NK) cells has been observed after systemic delivery of reovirus to cancer patients; however, the ability of OV to potentiate NK cell-mediated antibody-dependent cellular cytotoxicity (ADCC) is unexplored. This study elucidates the potential of oncolytic reovirus for the treatment of chronic lymphocytic leukaemia (CLL), both as a direct cytotoxic agent and as an immunomodulator. We demonstrate that reovirus: (i) is directly cytotoxic against CLL, which requires replication-competent virus; (ii) phenotypically and functionally activates patient NK cells via a monocyte-derived interferon-α (IFNα)-dependent mechanism; and (iii) enhances ADCC-mediated killing of CLL in combination with anti-CD20 antibodies. Our data provide strong preclinical evidence to support the use of reovirus in combination with anti-CD20 immunotherapy for the treatment of CLL.

Delivery programmes for elderly and isolated populations.

The provision of dental care for the elderly and for other isolated population groups cannot be ignored. In particular, special provision must be made for the housebound and institutionalized elderly as well as for those who are isolated for social or medical reasons. Continuous liason with social service personnel and health service workers, as well as with voluntary agencies, is essential for identifying and treating these populations. The assessment of dental treatment needs must take account of the clinical dental status of the subjects, their demands for treatment and their oral handicaps. The aims should be to treat overt oral and dental pathology and to relieve oral handicaps. Treatment should be readily available and must not be an added burden for those who are already medically or socially disadvantaged. Careful consideration must be given to treatment and manpower requirements. The dental team should consist of people who are particularly skilled at treating elderly and/or handicapped people. Schemes for domiciliary visits should be devised and facilities such as mobile dental units and dental surgeries within long-stay hospitals should be made available. Most importantly, in order to provide an appropriate ongoing dental service, dental personnel and other health workers must be totally committed to making quality dental health care available to all.

Precision trace gas analysis by FT-IR spectroscopy. 2. The 13C/12C isotope ratio of CO2.

We report the development of a method of carbon stable isotope ratio analysis based on 1-cm-1 resolution Fourier transform infrared (FT-IR) spectroscopy, deployable in both laboratory and field applications. We demonstrate the determination of the 13C/12C ratio of CO2 (i.e., delta 13CO2) in air with an analytical precision of the order of +/- 0.1/1000 (i.e., +/- 0.01%). The FT-IR method relies on calibration using synthetically calculated absorbance spectra and a multivariate calibration algorithm. The method requires no sample preparation other than optional drying of the sample and may be applied directly to ambient air samples containing approximately 350 mumol mol-1 CO2 (molar mixing ratio). It may also be applied to samples more concentrated in CO2, such as human breath, approximately 5% CO2. We demonstrate the utility of the technique to the analysis of delta 13CO2 in air during an experimental field campaign and to the laboratory-based analysis of human breath. A similar method could also be used to determine the H/D ratio in atmospheric water vapor.

Precision trace gas analysis by FT-IR spectroscopy. 1. Simultaneous analysis of CO2, CH4, N2O, and CO in air.

We report the development of a method of trace gas analysis based on 1-cm-1 resolution Fourier transform infrared (FT-IR) spectroscopy, deployable in both laboratory and field applications. Carbon dioxide, methane, nitrous oxide, and carbon monoxide may be analyzed simultaneously in a single air sample using this method. We have demonstrated that the method can provide analytical precision of the order of +/- 0.15 mumol mol-1 for CO2, +/- 0.9 nmol mol-1 for CH4, +/- 0.3 nmol mol-1 for N2O, and +/- 0.3 nmol mol-1 for CO, expressed as mole fractions in dry air. The analytical precision is in all cases competitive with or superior to that of the more usual methods of analysis for these trace gases, namely, nondispersive infrared spectroscopy for CO2 and gas chromatography-based techniques for CH4, N2O, and CO. The novel FT-IR method relies on calibration using synthetically calculated absorbance spectra and a chemometric multivariate calibration algorithm, classical least squares.