Marker-free image registration of electron tomography tilt-series

<p>Abstract</p> <p>Background</p> <p>Tilt series are commonly used in electron tomography as a means of collecting three-dimensional information from two-dimensional projections. A common problem encountered is the projection alignment prior to 3D reconstruction. Current alignment techniques usually employ gold particles or image derived markers to correctly align the images. When these markers are not present, correlation between adjacent views is used to align them. However, sequential pairwise correlation is prone to bias and the resulting alignment is not always optimal.</p> <p>Results</p> <p>In this paper we introduce an algorithm to find regions of the tilt series which can be tracked within a subseries of the tilt series. These regions act as landmarks allowing the determination of the alignment parameters. We show our results with synthetic data as well as experimental cryo electron tomography.</p> <p>Conclusion</p> <p>Our algorithm is able to correctly align a single-tilt tomographic series without the help of fiducial markers thanks to the detection of thousands of small image patches that can be tracked over a short number of images in the series.</p

Layer-Specific fMRI Reflects Different Neuronal Computations at Different Depths in Human V1

Recent work has established that cerebral blood flow is regulated at a spatial scale that can be resolved by high field fMRI to show cortical columns in humans. While cortical columns represent a cluster of neurons with similar response properties (spanning from the pial surface to the white matter), important information regarding neuronal interactions and computational processes is also contained within a single column, distributed across the six cortical lamina. A basic understanding of underlying neuronal circuitry or computations may be revealed through investigations of the distribution of neural responses at different cortical depths. In this study, we used T2-weighted imaging with 0.7 mm (isotropic) resolution to measure fMRI responses at different depths in the gray matter while human subjects observed images with either recognizable or scrambled (physically impossible) objects. Intact and scrambled images were partially occluded, resulting in clusters of activity distributed across primary visual cortex. A subset of the identified clusters of voxels showed a preference for scrambled objects over intact; in these clusters, the fMRI response in middle layers was stronger during the presentation of scrambled objects than during the presentation of intact objects. A second experiment, using stimuli targeted at either the magnocellular or the parvocellular visual pathway, shows that laminar profiles in response to parvocellular-targeted stimuli peak in more superficial layers. These findings provide new evidence for the differential sensitivity of high-field fMRI to modulations of the neural responses at different cortical depths

Steroid Hormone Control of Cell Death and Cell Survival: Molecular Insights Using RNAi

The insect steroid hormone ecdysone triggers programmed cell death of obsolete larval tissues during metamorphosis and provides a model system for understanding steroid hormone control of cell death and cell survival. Previous genome-wide expression studies of Drosophila larval salivary glands resulted in the identification of many genes associated with ecdysone-induced cell death and cell survival, but functional verification was lacking. In this study, we test functionally 460 of these genes using RNA interference in ecdysone-treated Drosophila l(2)mbn cells. Cell viability, cell morphology, cell proliferation, and apoptosis assays confirmed the effects of known genes and additionally resulted in the identification of six new pro-death related genes, including sorting nexin-like gene SH3PX1 and Sox box protein Sox14, and 18 new pro-survival genes. Identified genes were further characterized to determine their ecdysone dependency and potential function in cell death regulation. We found that the pro-survival function of five genes (Ras85D, Cp1, CG13784, CG32016, and CG33087), was dependent on ecdysone signaling. The TUNEL assay revealed an additional two genes (Kap-α3 and Smr) with an ecdysone-dependent cell survival function that was associated with reduced cell death. In vitro, Sox14 RNAi reduced the percentage of TUNEL-positive l(2)mbn cells (p<0.05) following ecdysone treatment, and Sox14 overexpression was sufficient to induce apoptosis. In vivo analyses of Sox14-RNAi animals revealed multiple phenotypes characteristic of aberrant or reduced ecdysone signaling, including defects in larval midgut and salivary gland destruction. These studies identify Sox14 as a positive regulator of ecdysone-mediated cell death and provide new insights into the molecular mechanisms underlying the ecdysone signaling network governing cell death and cell survival

Estudo comparativo preliminar entre os alongamentos proprioceptivo e estático passivo em pacientes com seqüelas de hanseníase

A proposta deste estudo foi comparar a aplicação de alongamento estático passivo e alongamento proprioceptivo no tratamento de seqüelas de hanseníase. Doze pacientes com essas seqüelas participaram da pesquisa, separados aleatoriamente em dois grupos: o grupo FNP, tratado com facilitação neuromuscular proprioceptiva, e o grupo AEP, com alongamento estático passivo. Ambos realizaram dez sessões de alongamentos, sendo submetidos à avaliação inicial e final nas quais foram aplicados o questionário SF-36, mensuradas a amplitude de movimento (ADM) do punho e tornozelo, testados os reflexos e a sensibilidade. No grupo FNP foi observada melhora na ADM do tornozelo e em três domínios do SF-36; no grupo AEP, em cinco domínios do SF-36. Quando comparados os grupos, o FNP obteve melhora significativa na extensão do punho, dorsiflexão e plantiflexão em relação ao AEP. A facilitação neuromuscular proprioceptiva parece ser um método mais eficaz para ganhar alongamento muscular e ADM de tornozelo e punho em pacientes com seqüelas de hanseníase. Não foi observada relação entre acréscimo na ADM e melhora na qualidade de vida relacionada à saúde nos pacientes dos dois grupos.The purpose of this study was to compare the effects of two kinds of stretching - passive, static stretching, and proprioceptive neuromuscular facilitation (PNF) - in patients with leprosy sequel. Twelve patients were randomly assigned into two groups: the PNF group and the SS group, that was submitted to static stretching. Both groups attended ten stretching sessions, being submitted to initial and final evaluations in which were assessed: health-related quality of life, by means of he SF-36 questionnaire; ankle and wrist range of motion (ROM); and sensitivity and reflex testing. Improvements in ankle movement and in three SF-36 domains were observed in PNF group; and in five SF-36 domains in SS group. PNF group showed better improvement in wrist extension and ankle movement than SS group. PNF seems to be a more effective method to increase flexibility and ankle and wrist range of motion in patients with leprosy sequelae. No relation was found between ROM improvement and perception of better health-related quality of life in any of the groups

Wnt/β-catenin pathway regulates <it>ABCB1</it> transcription in chronic myeloid leukemia

<p>Abstract</p> <p>Background</p> <p>The advanced phases of chronic myeloid leukemia (CML) are known to be more resistant to therapy. This resistance has been associated with the overexpression of <it>ABCB1</it>, which gives rise to the multidrug resistance (MDR) phenomenon. MDR is characterized by resistance to nonrelated drugs, and P-glycoprotein (encoded by <it>ABCB1</it>) has been implicated as the major cause of its emergence. Wnt signaling has been demonstrated to be important in several aspects of CML. Recently, Wnt signaling was linked to <it>ABCB1</it> regulation through its canonical pathway, which is mediated by β-catenin, in other types of cancer. In this study, we investigated the involvement of the Wnt/β-catenin pathway in the regulation of <it>ABCB1</it> transcription in CML, as the basal promoter of <it>ABCB1</it> has several β-catenin binding sites. β-catenin is the mediator of canonical Wnt signaling, which is important for CML progression.</p> <p>Methods</p> <p>In this work we used the K562 cell line and its derived MDR-resistant cell line Lucena (K562/VCR) as CML study models. Real time PCR (RT-qPCR), electrophoretic mobility shift assay (EMSA), chromatin immunoprecipitation (ChIP), flow cytometry (FACS), western blot, immunofluorescence, RNA knockdown (siRNA) and Luciferase reporter approaches were used.</p> <p>Results</p> <p>β-catenin was present in the protein complex on the basal promoter of <it>ABCB1</it> in both cell lines <it>in vitro</it>, but its binding was more pronounced in the resistant cell line <it>in vivo</it>. Lucena cells also exhibited higher β-catenin levels compared to its parental cell line. <it>Wnt1</it> and <it>β-catenin</it> depletion and overexpression of nuclear β-catenin, together with TCF binding sites activation demonstrated that <it>ABCB1</it> is positively regulated by the canonical pathway of Wnt signaling.</p> <p>Conclusions</p> <p>These results suggest, for the first time, that the Wnt/β-catenin pathway regulates <it>ABCB1</it> in CML.</p