Inhibition of Grb2 expression demonstrates an important role in BCR-ABL-mediated MAPK activation and transformation of primary human hematopoietic cells

Chronic myeloid leukemia (CML) results from the expression of the BCR/ABL oncogene in a primitive hematopoietic cell. However, BCR/ABL-activated signaling mechanisms are dependent on the cellular context in which it is expressed, and mechanisms underlying primitive human hematopoietic cell transformation by BCR-ABL are not well understood. Our previous studies have shown that BCR/ABL-Y177 has an essential role in Ras activation and human hematopoietic progenitor transformation in CML. The adapter protein growth factor receptor-binding protein-2 (Grb2) can bind phosphorylated BCR/ABL-Y177, induce Grb2-SoS complex formation and activate Ras signaling. We investigated the role of Grb2 in CML progenitor transformation by cotransducing human CD34+ cells with lentivirus vectors expressing short hairpin RNA to Grb2 and retrovirus vectors expressing BCR/ABL. We show that Grb2 knockdown significantly inhibits proliferation and survival of BCR-ABL-expressing CD34+ cells, but not control CD34+ cells. Grb2 knockdown reduced mitogen-activated protein kinase (MAPK) activity in BCR-ABL-expressing hematopoietic cells. We conclude that inhibition of Grb2 expression demonstrates an important role in BCR-ABL-mediated MAPK activation and transformation of primary human hematopoietic cells.These results support further investigation of downstream effectors of Grb2-mediated signals and targeting of Grb2 interactions in the treatment of CML.

Search for sneutrino production in eμ final states in 5.3 fb-1 of pp collisions at square root s =1.96 TeV

We report the results of a search for R parity violating (RPV) interactions leading to the production of supersymmetric sneutrinos decaying into eμ final states using 5.3 fb-1 of integrated luminosity collected by the D0 experiment at the Fermilab Tevatron Collider. Having observed no evidence for production of eμ resonances, we set direct bounds on the RPV couplings λ311' and λ312 as a function of sneutrino mass.

Comparison of performance of one-color and two-color gene-expression analyses in predicting clinical endpoints of neuroblastoma patients

Microarray-based prediction of clinical endpoints may be performed using either a one-color approach reflecting mRNA abundance in absolute intensity values or a two-color approach yielding ratios of fluorescent intensities. In this study, as part of the MAQC-II project, we systematically compared the classification performance resulting from one- and two-color gene-expression profiles of 478 neuroblastoma samples. In total, 196 classification models were applied to these measurements to predict four clinical endpoints, and classification performances were compared in terms of accuracy, area under the curve, Matthews correlation coefficient and root mean-squared error. Whereas prediction performance varied with distinct clinical endpoints and classification models, equivalent performance metrics were observed for one- and two-color measurements in both internal and external validation. Furthermore, overlap of selected signature genes correlated inversely with endpoint prediction difficulty. In summary, our data strongly substantiate that the choice of platform is not a primary factor for successful gene expression based-prediction of clinical endpoints.

Diagnostic value of adenosine deaminase in cerebrospinal fluid for tuberculous meningitis: a meta-analysis

OBJECTIVE

To determine the accuracy of adenosine deaminase (ADA) measurements in the diagnosis of tuberculous meningitis (TBM).

DESIGN

After a systematic review of English language studies, the sensitivity, specificity and accuracy of ADA concentrations in the diagnosis of cerebrospinal fluid (CSF) were evaluated using random effects models. Summary receiver operating characteristic curves were used to summarise overall test performance.

RESULTS

Ten studies met our inclusion criteria. The sensitivity of ADA in the diagnosis of TBM was 0.79 (95%CI 0.75-0.83), specificity 0.91 (95%CI 0.89-0.93), positive likelihood ratio 6.85 (95%CI 4.11-11.41), negative likelihood ratio 0.29 (95%CI 0.19-0.44) and diagnostic odds ratio 26.93 (95%CI 12.73-56.97).

CONCLUSION

Our data suggest that ADA in the CSF can be a sensitive and specific target and a critical criteria for the diagnosis of TBM.

Electron standing waves on the GaN(0001)-pseudo (1 × 1) surface: a FT-STM study at room temperature

We report the direct imaging of standing waves on a GaN(0001)-pseudo (1 × 1) metallic surface, which consists of two atomic Ga layers with the top layer incommensurate. Two types of periodic oscillation are observed by scanning tunneling microscopy at room temperature. The longer wavelength standing waves are due to electron scattering by dislocation-induced steps and two-dimensional InN islands. The localized shorter wavelength waves are attributed to a structural transition of the incommensurate Ga bilayer to a tetrahedral Ga bilayer after the growth of the InN islands.

Efficacy, safety, and ethics of cosmetic neurology far from settled

In this issue, Larriviere and colleagues discuss the emerging use of drugs to enhance cognitive function. Several cautions they raise warrant amplification. People have tried to pharmacologically improve cognitive function for millennia, but Larriviere and colleagues postulate that new, more effective drugs will lead to the emergence of  "cosmetic neurology." The ethics of using drugs to improve performance, as opposed to treating disease or restoring normal function, are far from settled.

Beliefs about the relative harm of "light" and "low tar" cigarettes: findings from the International Tobacco Control (ITC) China Survey

BACKGROUND

Many smokers in Western countries perceive "light" or "low tar" cigarettes as less harmful and less addictive than "regular" or "full flavoured" cigarettes. However, there is little research on whether similar perceptions exist among smokers in low and middle incomes, including China.

OBJECTIVE

To characterise beliefs about "light" and "low tar" cigarettes among adult urban smokers in China.

METHODS

We analysed data from Wave 1 of the ITC China Survey, a face-to-face household survey of 4732 adult Chinese smokers randomly selected from six cities in China in 2006. Households were sampled using a stratified multistage design.

FINDINGS

Half (50.0%) of smokers in our sample reported having ever tried a cigarette described as "light," "mild" or "low tar". The majority of smokers in our sample (71%) believed that "light" and/or "low tar" cigarettes are less harmful compared to "full flavoured" cigarettes. By far the strongest predictor of the belief that "light" and/or "low tar" cigarettes are less harmful was the belief that "light" and/or "low tar" cigarettes feel smoother on the respiratory system (p<0.001, OR=53.87, 95% CI 41.28 to 70.31).

CONCLUSION

Misperceptions about "light" and/or "low tar" cigarettes were strongly related to the belief that these cigarettes are smoother on the respiratory system. Future tobacco control policies should go beyond eliminating labelling and marketing that promotes "light" and "low tar" cigarettes by regulation of product characteristics (for example, additives, filter vents) that reinforce perceptions that "light" and "low tar" cigarettes are smoother on the respiratory system and therefore less harmful.

A cross-sectional study on levels of second-hand smoke in restaurants and bars in five cities in China

OBJECTIVES

To assess indoor second-hand smoke (SHS) exposure in restaurants and bars via PM(2.5) (fine particles 2.5 μm in diameter and smaller) level measurements in five cities in China.

METHODS

The study was conducted from July to September in 2007 in Beijing, Xi'an, Wuhan, Kunming and Guiyang. Portable aerosol monitors were used to measure PM(2.5) concentrations in 404 restaurants and bars. The occupant density and the active smoker density were calculated for each venue sampled.

RESULTS

Among the 404 surveyed venues, 23 had complete smoking bans, 9 had partial smoking bans and 313 (77.5%) were observed to have allowed smoking during sampling. The geometric mean of indoor PM(2.5) levels in venues with smoking observed was 208 μg/m(3) and 99 μg/m(3) in venues without observed smoking. When outdoor PM(2.5) levels were adjusted, indoor PM(2.5) levels in venues with smoking observed were consistently significantly higher than in venues without smoking observed (F=80.49, p<0.001). Indoor PM(2.5) levels were positively correlated with outdoor PM(2.5) levels (partial rho=0.37 p<0.001) and active smoker density (partial rho=0.34, p<0.001).

CONCLUSIONS

Consistent with findings in other countries, PM(2.5) levels in smoking places are significantly higher than those in smoke-free places and are strongly related to the number and density of active smokers. These findings document the high levels of SHS in hospitality venues in China and point to the urgent need for comprehensive smoke-free laws in China to protect the public from SHS hazards, as called for in Article 8 of the Framework Convention on Tobacco Control, which was ratified by China in 2005.

Low vitamin C and increased oxidative stress and cell death in mice that lack the sodium-dependent vitamin C transporter SVCT2

The sodium-dependent vitamin C transporter (SVCT2) is responsible for the transport of vitamin C into cells in multiple organs, from either the blood or the cerebrospinal fluid. Mice null for SVCT2 (SVCT2(-/-)) do not survive past birth but the cause of death has not yet been ascertained. After mating of SVCT2(+/-) males and SVCT2(+/-) females, fewer SVCT2(-/-) and SVCT2(+/-) progeny were observed than would be expected according to Mendelian ratios. Vitamin C levels in SVCT2(-/-), SVCT2(+/-), and SVCT2(+/+) were genotype-dependent. SVCT2(-/-) fetuses had significantly lower vitamin C levels than littermates in placenta, cortex, and lung, but not in liver (the site of vitamin C synthesis). Low vitamin C levels in placenta and cortex were associated with elevations in several markers of oxidative stress: malondialdehyde, isoketals, F(2)-isoprostanes, and F(4)-neuroprostanes. Oxidative stress was not elevated in fetal SVCT2(-/-) lung tissue despite low vitamin C levels. In addition to the expected severe hemorrhage in cortex, we also found hemorrhage in the brain stem, which was accompanied by cell loss. We found evidence of increased apoptosis in SVCT2(-/-) mice and disruption of the basement membrane in fetal brain. Together these data show that SVCT2 is critical for maintaining vitamin C levels in fetal and placental tissues and that the lack of SVCT2, and the resulting low vitamin C levels, results in fetal death and, in SVCT2(-/-) mice that survive the gestation period, in oxidative stress and cell death.