Engineered doping of organic semiconductors for enhanced thermoelectric efficiency

Significant improvements to the thermoelectric figure of merit ZT have emerged in recent years, primarily due to the engineering of material composition and nanostructure in inorganic semiconductors (ISCs). However, many present high-ZT materials are based on low-abundance elements that pose challenges for scale-up, as they entail high material costs in addition to brittleness and difficulty in large-area deposition. Here we demonstrate a strategy to improve ZT in conductive polymers and other organic semiconductors (OSCs) for which the base elements are earth-abundant. By minimizing total dopant volume, we show that all three parameters constituting ZT vary in a manner so that ZT increases; this stands in sharp contrast to ISCs, for which these parameters have trade-offs. Reducing dopant volume is found to be as important as optimizing carrier concentration when maximizing ZT in OSCs. Implementing this strategy with the dopant poly(styrenesulphonate) in poly(3,4-ethylenedioxythiophene), we achieve ZT  =  0.42 at room temperature.

A universal scaling law between gray matter and white matter of cerebral cortex

Neocortex, a new and rapidly evolving brain structure in mammals, has a similar layered architecture in species over a wide range of brain sizes. Larger brains require longer fibers to communicate between distant cortical areas; the volume of the white matter that contains long axons increases disproportionally faster than the volume of the gray matter that contains cell bodies, dendrites, and axons for local information processing, according to a power law. The theoretical analysis presented here shows how this remarkable anatomical regularity might arise naturally as a consequence of the local uniformity of the cortex and the requirement for compact arrangement of long axonal fibers. The predicted power law with an exponent of 4/3 minus a small correction for the thickness of the cortex accurately accounts for empirical data spanning several orders of magnitude in brain sizes for various mammalian species, including human and nonhuman primates.

Interpreting neuronal population activity by reconstruction: unified framework with application to hippocampal place cells

Physical variables such as the orientation of a line in the visual field or the location of the body in space are coded as activity levels in populations of neurons. Reconstruction or decoding is an inverse problem in which the physical variables are estimated from observed neural activity. Reconstruction is useful first in quantifying how much information about the physical variables is present in the population and, second, in providing insight into how the brain might use distributed representations in solving related computational problems such as visual object recognition and spatial navigation. Two classes of reconstruction methods, namely, probabilistic or Bayesian methods and basis function methods, are discussed. They include important existing methods as special cases, such as population vector coding, optimal linear estimation, and template matching. As a representative example for the reconstruction problem, different methods were applied to multi-electrode spike train data from hippocampal place cells in freely moving rats. The reconstruction accuracy of the trajectories of the rats was compared for the different methods. Bayesian methods were especially accurate when a continuity constraint was enforced, and the best errors were within a factor of two of the information-theoretic limit on how accurate any reconstruction can be and were comparable with the intrinsic experimental errors in position tracking. In addition, the reconstruction analysis uncovered some interesting aspects of place cell activity, such as the tendency for erratic jumps of the reconstructed trajectory when the animal stopped running. In general, the theoretical values of the minimal achievable reconstruction errors quantify how accurately a physical variable is encoded in the neuronal population in the sense of mean square error, regardless of the method used for reading out the information. One related result is that the theoretical accuracy is independent of the width of the Gaussian tuning function only in two dimensions. Finally, all the reconstruction methods considered in this paper can be implemented by a unified neural network architecture, which the brain feasibly could use to solve related problems.

A 5-bp deletion in ELOVL4 is associated with two related forms of autosomal dominant macular dystrophy

Stargardt-like macular dystrophy (STGD3, MIM 600110) and autosomal dominant macular dystrophy (adMD) are inherited forms of macular degeneration characterized by decreased visual acuity, macular atrophy and extensive fundus flecks. Genetic mapping data suggest that mutations in a single gene may be responsible for both conditions, already known to bear clinical resemblance. Here we limit the minimum genetic region for STGD3 and adMD to a 0.6-cM interval by recombination breakpoint mapping and identify a single 5-bp deletion within the protein-coding region of a new retinal photoreceptor-specific gene, ELOVL4, in all affected members of STGD3 and adMD families. Bioinformatic analysis of ELOVL4 revealed that it has homology to a group of yeast proteins that function in the biosynthesis of very long chain fatty acids. Our results are therefore the first to implicate the biosynthesis of fatty acids in the pathogenesis of inherited macular degeneration.

The Drosophila spitz gene encodes a putative EGF-like growth factor involved in dorsal-ventral axis formation and neurogenesis

We describe the molecular characterization of the Drosophila gene spitz (spi), which encodes a putative 26-kD, EGF-like transmembrane protein that is structurally similar to TGF-alpha. Temporal and spatial expression patterns of spi transcripts indicate that spi is expressed throughout the embryo. Examination of mutant embryos reveals that spi is involved in a number of unrelated developmental choices, for example, dorsal-ventral axis formation, glial migration, sensory organ determination, and muscle development. We propose that spi may act as a ligand for cell-specific receptors, possibly rhomboid and/or the Drosophila EGF receptor homolog.

FZD7 has a critical role in cell proliferation in triple negative breast cancer

Breast cancer is genetically and clinically heterogeneous. Triple negative breast cancer (TNBC) is a subtype of breast cancer that is usually associated with poor outcome and lack of benefit from targeted therapy. We used microarray analysis to perform a pathway analysis of TNBC compared with non-triple negative breast cancer (non-TNBC). Overexpression of several Wnt pathway genes, such as frizzled homolog 7 (FZD7), low density lipoprotein receptor-related protein 6 and transcription factor 7 (TCF7) was observed in TNBC, and we directed our focus to the Wnt pathway receptor, FZD7. To validate the function of FZD7, FZD7shRNA was used to knock down FZD7 expression. Notably, reduced cell proliferation and suppressed invasiveness and colony formation were observed in TNBC MDA-MB-231 and BT-20 cells. Study of the possible mechanism indicated that these effects occurred through silencing of the canonical Wnt signaling pathway, as evidenced by loss of nuclear accumulation of β-catenin and decreased transcriptional activity of TCF7. In vivo studies revealed that FZD7shRNA significantly suppressed tumor formation, through reduced cell proliferation, in mice bearing xenografts without FZD7 expression. Our findings suggest that FZD7-involved canonical Wnt signaling pathway is essential for tumorigenesis of TNBC, and thus, FZD7 shows promise as a biomarker and a potential therapeutic target for TNBC.

Observation of electron-antineutrino disappearance at Daya Bay

The Daya Bay Reactor Neutrino Experiment has measured a nonzero value for the neutrino mixing angle θ(13) with a significance of 5.2 standard deviations. Antineutrinos from six 2.9 GWth reactors were detected in six antineutrino detectors deployed in two near (flux-weighted baseline 470 m and 576 m) and one far (1648 m) underground experimental halls. With a 43,000 ton-GWth-day live-time exposure in 55 days, 10,416 (80,376) electron-antineutrino candidates were detected at the far hall (near halls). The ratio of the observed to expected number of antineutrinos at the far hall is R=0.940±0.011(stat.)±0.004(syst.). A rate-only analysis finds sin(2)2θ(13)=0.092±0.016(stat.)±0.005(syst.) in a three-neutrino framework.

Enhanced human IgE production results from exposure to the aromatic hydrocarbons from diesel exhaust: direct effects on B-cell IgE production

Epidemiologic and experimental studies suggest that air pollution, and particularly diesel exhaust particles (DEPs) may play a role in the increasing prevalence and severity of airway allergic disease. We show that the extract of polyaromatic hydrocarbons (PAHs) from DEPs (PAH-DEP) enhances human IgE production from purified B cells. Interleukin-4 plus CD40 monoclonal antibody-stimulated IgE production was enhanced 20% to 360% by the addition of PAH-DEP over a period of 10 to 14 days. This effect was increased when PAH-DEP was added 2 to 5 days after cultures were initiated. PAH-DEP itself did not induce IgE production or synergize with interleukin-4 alone to induce IgE from purified B cells, suggesting that it was enhancing ongoing IgE production rather than inducing germline transcription or isotype switching. The prototype nonmetabolized aromatic hydrocarbon 2,3,7,8 tetracholorodibenzo-p-dioxin, which functions solely through activation of the cytosolic aromatic hydrocarbon receptor complex, also increased IgE production. Additionally, the pattern of mRNAs coding for distinct isoforms of the epsilon chain was altered by PAH-DEP, and B-cell expression of the low-affinity IgE receptor was upregulated by PAH-DEP. Enhanced IgE production in the human airway, resulting from exposure to PAH-DEP, may be an important factor in the increase in airway allergic disease.

Neuronal tuning: To sharpen or broaden?

Sensory and motor variables are typically represented by a population of broadly tuned neurons. A coarser representation with broader tuning can often improve coding accuracy, but sometimes the accuracy may also improve with sharper tuning. The theoretical analysis here shows that the relationship between tuning width and accuracy depends crucially on the dimension of the encoded variable. A general rule is derived for how the Fisher information scales with the tuning width, regardless of the exact shape of the tuning function, the probability distribution of spikes, and allowing some correlated noise between neurons. These results demonstrate a universal dimensionality effect in neural population coding.

Changing sexual attitudes and behaviour in China: implications for the spread of HIV and other sexually transmitted diseases

In Imperial China sexual behaviour was regarded as an indispensable activity to reach harmony with the universe, through the unity of the interaction of two opposing forces: yin and yang. Sexual intercourse was accepted when linked to procreation within a family context, while an individual's sexuality was not considered important. Homosexuality was tolerated although not advocated, while masturbation was denounced. Since the One Child Family and Open Door policies in the 1970s and the economic reforms of the 1980s, attitudes towards sexuality in China have changed. Premarital sex has become widely accepted among young people and people in China are now more tolerant toward extramarital sex. Nowadays young people consider that love should dominate marriage and the quality of an individual's sex life is currently more valued than it used to be. Attitudes towards masturbation have become more tolerant and though homosexuality has been hidden by society for a long time, in recent years it has begun to be considered as a legitimate lifestyle choice. Attitudes towards sex and sexual behaviour have become recognized as an individuals' responsibility as long as no offence occurs against society or the interests of other individuals, resulting in the recognition of diversity of sexual behaviour. As part of the changing attitudes to sex and sexual behaviour, heterosexual transmission is becoming the most important route of HIV transmission in China. This is complicated by the internal migration of an estimated 120 million labourers moving from the countryside to the cities as the result of economic reforms, most of whom are sexually active young men. Unless addressed directly, these factors may add to the estimated 300,000 HIV-infected Chinese, further fuelling an already rapidly spreading epidemic. The ramifications of the Chinese HIV epidemic will not only be felt within China, but also within the surrounding Asian countries thereby fuelling the HIV pandemic.

Interleukin-17 promotes prostate cancer via MMP7-induced epithelial-to-mesenchymal transition

Chronic inflammation has been associated with a variety of human cancers including prostate cancer. Interleukin-17 (IL-17) is a critical pro-inflammatory cytokine, which has been demonstrated to promote development of prostate cancer, colon cancer, skin cancer, breast cancer, lung cancer, and pancreas cancer. IL-17 promotes prostate adenocarcinoma with a concurrent increase of matrix metalloproteinase 7 (MMP7) expression in mouse prostate. Whether MMP7 mediates IL-17’s action and the underlying mechanisms remain unknown. We generated Mmp7 and Pten double knockout (Mmp7^−/− in abbreviation) mouse model and demonstrated that MMP7 promotes prostate adenocarcinoma through induction of epithelial-to-mesenchymal transition (EMT) in Pten-null mice. MMP7 disrupted E-cadherin/β-catenin complex to up-regulate EMT transcription factors in mouse prostate tumors. IL-17 receptor C and Pten double knockout mice recapitulated the weak EMT characteristics observed in Mmp7^−/− mice. IL-17 induced MMP7 and EMT in human prostate cancer LNCaP, C4-2B, and PC-3 cell lines, while siRNA knockdown of MMP7 inhibited IL-17-induced EMT. Compound III, a selective MMP7 inhibitor, decreased development of invasive prostate cancer in Pten single knockout mice. In human normal prostates and prostate tumors, IL-17 mRNA levels were positively correlated with MMP7 mRNA levels. These findings demonstrate that MMP7 mediates IL-17’s function in promoting prostate carcinogenesis through induction of EMT, indicating IL-17-MMP7-EMT axis as potential targets for developing new strategies in the prevention and treatment of prostate cancer.

Transformation of NIH 3T3 cells by HER3 or HER4 receptors requires the presence of HER1 or HER2

Members of the epidermal growth factor receptor (EGFR) subfamily of receptor protein tyrosine kinases have been implicated in the pathogenesis of various malignancies. The ability of one EGFR subfamily member to influence, or function synergistically with, another is likely to be a general feature of these receptors. To assess the role of receptor heterodimerization, we analyzed the ability of Neu differentiation factor (NDF) to induce cell growth and transformation of NIH 3T3 cells transfected with different combinations of the EGFR subfamily of receptors. NDF induced mitogenesis, but not transformation, of cells expressing either HER3 or HER4 alone. However, NDF-induced cell transformation was observed when either HER1 or HER2 was coexpressed with HER3 or HER4. In analogous receptor phosphorylation experiments, NDF-induced transphosphorylation appears to be correlated with synergistic transformation of NIH 3T3 cells. Interestingly, transphosphorylation between HER1 and HER4 can be stimulated by either EGF or NDF.

Suppression of c-ras transformation by GTPase-activating protein

The ras genes are required for normal cell growth and mediate transformation by oncogenes encoding protein tyrosine kinases. Normal ras can transform cells in vitro and in vivo, but mutationally activated ras does so much more efficiently, and highly transforming mutant versions of ras have been isolated from a variety of human and animal tumours. The ras genes encode membrane-associated, guanine nucleotide-binding proteins that are active when GTP is bound and inactive when GDP is bound. The slow intrinsic GTPase activity of normal mammalian Ras proteins can be greatly accelerated by the GTPase-activating protein (GAP), which is predominantly cytoplasmic. This activity of GAP, which can increase with cell density in contact-inhibited cells, suggests that it functions as a negative, upstream regulator of ras. Other studies, however, show that GAP interacts with a region of ras-encoded protein implicated in ras effector function, which raises the possibility that GAP might also be a downstream target of ras. Mutationally activated ras-encoded proteins also interact with GAP, although they are resistant to its catalytic activity. In an attempt to define the role of GAP in ras-mediated transformation, we examined the effects on transformation of normal or mutant ras when cells overexpress GAP. We found that GAP suppresses transformation of NIH 3T3 cells by normal Ha-ras (c-ras) but does not inhibit transformation by activated Ha-ras (v-ras). These results support the hypothesis that GAP functions as a negative regulator of normal ras and make it unlikely that GAP alone is the ras target.

Final results from the large sunitinib global expanded-access trial in metastatic renal cell carcinoma

BACKGROUND

We report final results with extended follow-up from a global, expanded-access trial that pre-regulatory approval provided sunitinib to metastatic renal cell carcinoma (mRCC) patients, ineligible for registration-directed trials.

METHODS

Patients ⩾18 years received oral sunitinib 50 mg per day on a 4-weeks-on-2-weeks-off schedule. Safety was assessed regularly. Tumour measurements were scheduled per local practice.

RESULTS

A total of 4543 patients received sunitinib. Median treatment duration and follow-up were 7.5 and 13.6 months. Objective response rate was 16% (95% confidence interval (CI): 15-17). Median progression-free survival (PFS) and overall survival (OS) were 9.4 months (95% CI: 8.8-10.0) and 18.7 months (95% CI: 17.5-19.5). Median PFS in subgroups of interest: aged ⩾65 years (33%), 10.1 months; Eastern Cooperative Oncology Group performance status ⩾2 (14%), 3.5 months; non-clear cell histology (12%), 6.0 months; and brain metastases (7%), 5.3 months. OS was strongly associated with the International Metastatic Renal-Cell Carcinoma Database Consortium prognostic model (n=4065). The most common grade 3/4 treatment-related adverse events were thrombocytopenia (10%), fatigue (9%), and asthenia, neutropenia, and hand-foot syndrome (each 7%).

CONCLUSION

Final analysis of the sunitinib expanded-access trial provided a good opportunity to evaluate the long-term side effects of a tyrosine kinase inhibitor used worldwide in mRCC. Efficacy and safety findings were consistent with previous results.

Statistically efficient estimation using population coding

Coarse codes are widely used throughout the brain to encode sensory and motor variables. Methods designed to interpret these codes, such as population vector analysis, are either inefficient (the variance of the estimate is much larger than the smallest possible variance) or biologically implausible, like maximum likelihood. Moreover, these methods attempt to compute a scalar or vector estimate of the encoded variable. Neurons are faced with a similar estimation problem. They must read out the responses of the presynaptic neurons, but, by contrast, they typically encode the variable with a further population code rather than as a scalar. We show how a nonlinear recurrent network can be used to perform estimation in a near-optimal way while keeping the estimate in a coarse code format. This work suggests that lateral connections in the cortex may be involved in cleaning up uncorrelated noise among neurons representing similar variables.

A role for C-C chemokines in fibrotic lung disease

Pulmonary fibrosis is the end point of a chronic inflammatory process characterized by leukocyte recruitment and activation, fibroblast proliferation, and increased extracellular matrix production. Previous studies of models of pulmonary fibrosis have investigated the role of cytokines in the evolution of the fibrotic response. The involvement of tumor necrosis factor and interleukin-1 in bleomycin-induced lung injury, a model of idiopathic pulmonary fibrosis, has been well established, suggesting that cytokines mediate the initiation and maintenance of chronic inflammatory lesions. However, the aforementioned cytokines alone cannot account for the recruitment and activation of specific leukocyte populations found in the bleomycin model. Recently, a family of novel proinflammatory cytokines (chemokines) was cloned and characterized, yielding many putative mediators of leukocyte functions. Macrophage inflammatory protein-1 alpha (MIP-1 alpha) and monocyte chemoattractant protein-1 (MCP-1) belong to the C-C chemotactic cytokine family, a group of low-molecular-weight peptides. These molecules modulate chemotaxis, proliferation, and cytokine expression in leukocyte subsets. Our group has investigated the roles of MCP-1 and MIP-1 alpha in the bleomycin model. Both MCP-1 and MIP-1 alpha are expressed in a time-dependent manner after bleomycin challenge, and passive immunization of these animals with either anti-MIP-1 alpha or anti-MCP-1 antibodies attenuated leukocyte accumulation. In addition, we have identified specific cell types expressing MCP-1 or MIP-1 alpha by in situ hybridization and immunohistochemical localization, respectively. Furthermore, our results indicate that MIP-1 alpha expression is mediated by alveolar macrophage-derived tumor necrosis factor, identifying an important cytokine pathway in the initiation of pulmonary fibrosis. Finally, anti-MIP-1 alpha therapy attenuated fibrosis, providing direct evidence for its involvement in fibrotic pathology. Our work has clearly established that the C-C chemokines MCP-1 and MIP-1 alpha are expressed and contribute to the initiation and maintenance of the bleomycin-induced pulmonary lesion.