Identifying Biomagnetic Sources in the Brain by the Maximum Entropy Approach

Magnetoencephalographic (MEG) measurements record magnetic fields generated from neurons while information is being processed in the brain. The inverse problem of identifying sources of biomagnetic fields and deducing their intensities from MEG measurements is ill-posed when the number of field detectors is far less than the number of sources. This problem is less severe if there is already a reasonable prior knowledge in the form of a distribution in the intensity of source activation. In this case the problem of identifying and deducing source intensities may be transformed to one of using the MEG data to update a prior distribution to a posterior distribution. Here we report on some work done using the maximum entropy method (ME) as an updating tool. Specifically, we propose an implementation of the ME method in cases when the prior contain almost no knowledge of source activation. Two examples are studied, in which part of motor cortex is activated with uniform and varying intensities, respectively.Comment: 8 pages, 8 figures. Presented at 25th International Workshop on Bayesian Inference and Maximum Entropy Methods in Science and Engineering, San Jose, CA, USA Aug 7-12, 200

Mapping the history and current situation of research on John Cunningham virus – a bibliometric analysis

<p>Abstract</p> <p>Background</p> <p>John Cunningham virus (JCV) constitutes a family of polyoma viruses, which plays important roles in the progressive multifocal leukoencephalopathy (PML) and tumorigenesis. However, no bibliometric investigation has been reported to guide the researchers and potential readers.</p> <p>Methods</p> <p>Papers were collected from database Sci-expanded and Pubmed until May 22, 2008. The highly-productive authors, institutes and countries, highly-cited authors and journals were ranked. The highly-cited articles were subjected to co-citation and chronological analysis with highly-frequent MeSH words for co-occurrence analysis.</p> <p>Results</p> <p>Until now, 1785 articles about JCV were indexed in Sci-expanded and 1506 in Pubmed. The main document type was original article. USA, Japan and Italy were the largest three producers about JCV. Temple University published 128 papers and ranked the top, followed by University of Tokyo. Khalili K and Yogo Y became the core authors due to more than 20 documents produced. Journal of Neurovirology published more than 15 papers and ranked the top. Padgett BL and Berger JR were the first two highly-cited authors. Journal of Virology and Journal of Neurovirology respectively ranked to the first two highly-cited journals. These top highly-cited articles were divided into 5 aspects: (1) The correlation between JC virus and tumors; (2) Causal correlation of JCV with PML; (3) Polyoma virus infection and its related diseases in renal-allograft recipients; (4) Detection of JCV antibody, oncogene and its encoding protein; (5) Genetics and molecular biology of JCV. The MeSH/subheadings were classified into five groups: (1) JCV and virus infectious diseases; (2) JCV pathogenicity and pathological appearance of PML; (3) JCV isolation and detection; (4) Immunology of JCV and PML; (5) JCV genetics and tumors.</p> <p>Conclusion</p> <p>JCV investigation mainly focused on its isolation and detection, as well as its correlation with PML and tumors. Establishment of transgenic animal model using JCV T antigen would be a hopeful and useful project in the further study.</p

Lead, cadmium and aluminum in Canadian infant formulae, oral electrolytes and glucose solutions

Lead (Pb), cadmium (Cd) and aluminum (Al) were determined in 437 individual samples of infant formulae, oral electrolytes and 5% glucose solutions available in Canada. In the electrolytes, Cd and Pb concentrations were all below 0.01 and 0.041 ng g−1, respectively. In the 5% glucose solutions, Pb and Cd levels averaged 0.01 and 0.09 ng g−1, respectively. Reported on an as-consumed basis, Pb levels in milk- and soya-based formulae averaged 0.90 and 1.45 ng g−1, respectively, while Cd levels averaged 0.23 and 1.18 ng g−1, respectively Average Al levels on an as-consumed basis were 440 ng g−1 (range 10–3400 ng g−1) in milk-based formulae and 730 ng g−1 (range 230–1100 ng g−1) in soy-based formulae. Al concentrations increased in the following order: plain formula < low-iron formula < iron-supplemented formula < casein hydrolysate formula ≈ premature formula ≤ soy formula. For example, in the powdered formulae, average Al concentrations were 18 ng g−1 for plain milk-based, 37 ng g−1 for low-iron, 128 ng g−1 for iron supplemented, 462 ng g−1 for lactose-free, 518 ng g−1 for hypoallergenic and 619 ng g−1 for soy-based formula. Al concentrations, as-consumed, increased with decreasing levels of concentration: powder < concentrated liquid < ready-to-use. Formulae stored in glass bottles contained between 100 and 300 ng g−1 more Al than the same formulae stored in cans. The source of the increased Al did not appear to be the glass itself, because most electrolytes and glucose solutions, also stored in glass, contained less than 8 ng g−1 Al. Corresponding differences in Pb and Cd levels were not observed. Al concentrations varied substantially among manufacturers; however, all manufacturers were able to produce plain milk-based formulae containing less than 50 ng g−1 Al, i.e. within the range of Al concentrations found in human milk. Next to soya-based and hypoallergenic formulae, premature formulae contained among the highest concentrations of Al, ranging 851–909 ng g−1 from one manufacturer and 365–461 ng g−1 from another

Upregulated sirtuin 1 by miRNA-34a is required for smooth muscle cell differentiation from pluripotent stem cells

© 2015 Macmillan Publishers Limited. All rights reserved. microRNA-34a (miR-34a) and sirtuin 1 (SirT1) have been extensively studied in tumour biology and longevityaging, but little is known about their functional roles in smooth muscle cell (SMC) differentiation from pluripotent stem cells. Using well-established SMC differentiation models, we have demonstrated that miR-34a has an important role in SMC differentiation from murine and human embryonic stem cells. Surprisingly, deacetylase sirtuin 1 (SirT1), one of the top predicted targets, was positively regulated by miR-34a during SMC differentiation. Mechanistically, we demonstrated that miR-34a promoted differentiating stem cells' arrest at G0G1 phase and observed a significantly decreased incorporation of miR-34a and SirT1 RNA into Ago2-RISC complex upon SMC differentiation. Importantly, we have identified SirT1 as a transcriptional activator in the regulation of SMC gene programme. Finally, our data showed that SirT1 modulated the enrichment of H3K9 tri-methylation around the SMC gene-promoter regions. Taken together, our data reveal a specific regulatory pathway that miR-34a positively regulates its target gene SirT1 in a cellular context-dependent and sequence-specific manner and suggest a functional role for this pathway in SMC differentiation from stem cells in vitro and in vivo

Weak up-regulation of serum response factor in gastric ulcers in patients with co-morbidities is associated with increased risk of recurrent bleeding

<p>Abstract</p> <p>Background</p> <p>Serum response factor (SRF) is crucial for gastric ulcer healing process. The study determined if gastric ulcer tissues up-regulate SRF and if such up-regulation correlated with co-morbidities and the risk of recurrent bleeding.</p> <p>Methods</p> <p>Ulcer and non-ulcer tissues were obtained from 142 patients with active gastric ulcers for SRF expression assessed by immunohistochemistry. Based on the degree of SRF expression between these two tissue types, SRF up-regulation was classified as strong, intermediate, and weak patterns. The patients were followed-up to determine if SRF up-regulation correlated to recurrent bleeding.</p> <p>Results</p> <p>Gastric ulcer tissues had higher SRF expression than non-ulcer tissues (<it>p </it>< 0.05). Patients with strong SRF up-regulation had lower rates of stigmata of recent hemorrhage (SRH) on the ulcer base than the others (<it>p </it>< 0.05). Multivariate logistic regression confirmed that co-morbidities and weak SRF up-regulation were two independent factors of recurrent gastric ulcer bleeding (<it>p </it>< 0.05). Combining both factors, there was an 8.29-fold (95% CI, 1.31~52.62; <it>p </it>= 0.03) higher risk of recurrent gastric ulcer bleeding.</p> <p>Conclusions</p> <p>SRF expression is higher in gastric ulcer tissues than in non-ulcer tissues. Weak SRF up-regulation, combined with the presence of co-morbidities, increase the risk of the recurrent gastric ulcer bleeding.</p

Laboratory layered latte

Inducing thermal gradients in fluid systems with initial, well-defined density gradients results in the formation of distinct layered patterns, such as those observed in the ocean due to double-diffusive convection. In contrast, layered composite fluids are sometimes observed in confined systems of rather chaotic initial states, for example, lattes formed by pouring espresso into a glass of warm milk. Here, we report controlled experiments injecting a fluid into a miscible phase and show that, above a critical injection velocity, layering emerges over a time scale of minutes. We identify critical conditions to produce the layering, and relate the results quantitatively to double-diffusive convection. Based on this understanding, we show how to employ this single-step process to produce layered structures in soft materials, where the local elastic properties vary step-wise along the length of the material

Long-Distance Signals Are Required for Morphogenesis of the Regenerating Xenopus Tadpole Tail, as Shown by Femtosecond-Laser Ablation

tadpoles has recently emerged as an important model for these studies; we explored the role of the spinal cord during tadpole tail regeneration.Using ultrafast lasers to ablate cells, and Geometric Morphometrics to quantitatively analyze regenerate morphology, we explored the influence of different cell populations. For at least twenty-four hours after amputation (hpa), laser-induced damage to the dorsal midline affected the morphology of the regenerated tail; damage induced 48 hpa or later did not. Targeting different positions along the anterior-posterior (AP) axis caused different shape changes in the regenerate. Interestingly, damaging two positions affected regenerate morphology in a qualitatively different way than did damaging either position alone. Quantitative comparison of regenerate shapes provided strong evidence against a gradient and for the existence of position-specific morphogenetic information along the entire AP axis.We infer that there is a conduit of morphology-influencing information that requires a continuous dorsal midline, particularly an undamaged spinal cord. Contrary to expectation, this information is not in a gradient and it is not localized to the regeneration bud. We present a model of morphogenetic information flow from tissue undamaged by amputation and conclude that studies of information coming from far outside the amputation plane and regeneration bud will be critical for understanding regeneration and for translating fundamental understanding into biomedical approaches

Association of Alpha B-Crystallin Genotypes with Oral Cancer Susceptibility, Survival, and Recurrence in Taiwan

BACKGROUND: Alpha B-crystallin (CRYAB) is a protein that functions as "molecular chaperone" in preserving intracellular architecture and cell membrane. Also, CRYAB is highly antiapoptotic. Abnormal CRYAB expression is a prognostic biomarker for oral cancer, while its genomic variations and the association with carcinogenesis have never been studied. METHODOLOGY/FINDING: Therefore, we hypothesized that CRYAB single nucleotide polymorphisms may be associated with oral cancer risk. In this hospital-based study, the association of CRYAB A-1215G (rs2228387), C-802G (rs14133) and intron2 (rs2070894) polymorphisms with oral cancer in a Taiwan population was investigated. In total, 496 oral cancer patients and 992 age- and gender-matched healthy controls were genotyped and analyzed. A significantly different frequency distribution was found in CRYAB C-802G genotypes, but not in A-1215G and intron2 genotypes, between the oral cancer and control groups. The CRYAB C-802G G allele conferred an increased risk of oral cancer (P = 1.49×10(-5)). Patients carrying CG/GG at CRYAB C-802G were of lower 5-year survival and higher recurrence rate than those of CC (P<0.05). CONCLUSION/SIGNIFICANCE: Our results provide the first evidence that the G allele of CRYAB C-802G is correlated with oral cancer risk and this polymorphism may be a useful marker for oral cancer recurrence and survival prediction for clinical reference

Identification of Human Fibroblast Cell Lines as a Feeder Layer for Human Corneal Epithelial Regeneration

There is a great interest in using epithelium generated in vitro for tissue bioengineering. Mouse 3T3 fibroblasts have been used as a feeder layer to cultivate human epithelia including corneal epithelial cells for more than 3 decades. To avoid the use of xeno-components, we evaluated human fibroblasts as an alternative feeder supporting human corneal epithelial regeneration. Five human fibroblast cell lines were used for evaluation with mouse 3T3 fibroblasts as a control. Human epithelial cells isolated from fresh corneal limbal tissue were seeded on these feeders. Colony forming efficiency (CFE) and cell growth capacity were evaluated on days 5–14. The phenotype of the regenerated epithelia was evaluated by morphology and immunostaining with epithelial markers. cDNA microarray was used to analyze the gene expression profile of the supportive human fibroblasts. Among 5 strains of human fibroblasts evaluated, two newborn foreskin fibroblast cell lines, Hs68 and CCD1112Sk, were identified to strongly support human corneal epithelial growth. Tested for 10 passages, these fibroblasts continually showed a comparative efficiency to the 3T3 feeder layer for CFE and growth capacity of human corneal epithelial cells. Limbal epithelial cells seeded at 1×104 in a 35-mm dish (9.6 cm2) grew to confluence (about 1.87–2.41×106 cells) in 12–14 days, representing 187–241 fold expansion with over 7–8 doublings on these human feeders. The regenerated epithelia expressed K3, K12, connexin 43, p63, EGFR and integrin β1, resembling the phenotype of human corneal epithelium. DNA microarray revealed 3 up-regulated and 10 down-regulated genes, which may be involved in the functions of human fibroblast feeders. These findings demonstrate that commercial human fibroblast cell lines support human corneal epithelial regeneration, and have potential use in tissue bioengineering for corneal reconstruction