4,804 research outputs found
Neural Networks Skin Tumor Diagnostic System
In this study, a malignant melanoma diagnostic system is designed using a straightforward neural network with the back-propagation learning algorithm. Eleven features are automatically extracted from skin tumor images. The correct diagnostic rate of this system is better than the average rate of 16 dermatologists who based their diagnosis with only the slide images
A Novel Morphological Operator to Calculate Euler Number
This paper introduces a novel morphological operator to calculate the Euler number for binary images. The operator is based on the condition of eight-connectedness for foreground and four-connectedness for background. It is significantly faster than the previous operators. The morphological operations used in border detection are discusse
Spd2 assists Spd1 in modulation of RNR architecture but does not regulate deoxynucleotide pools
In yeasts, small intrinsically disordered proteins (IDPs) modulate ribonucleotide reductase (RNR) activity to ensure an optimal supply of dNTPs for DNA synthesis. The S. pombe Spd1 protein can directly inhibit the large RNR subunit (R1), import the small subunit (R2) into the nucleus and induce an architectural change in the R1-R2 holocomplex. Here, we report the characterization of Spd2, a protein with homology to Spd1. We show that Spd2 is a CRL4Cdt2 controlled IDP that functions together with Spd1 in the DNA damage response and in modulation of RNR architecture. However, Spd2 does not regulate dNTP pools and R2 nuclear import. Furthermore, deletion of spd2 only weakly suppresses the Rad3ATR checkpoint dependency of CRL4Cdt2 mutants. However, when we raised intracellular dNTP pools by inactivation of RNR feedback inhibition, deletion of spd2 could suppress the checkpoint dependency of CRL4Cdt2 mutant cells to the same extent as spd1. Collectively, these observations suggest that Spd1 on its own regulates dNTP pools, while it together with Spd2 modulates RNR architecture and sensitizes cells to DNA damage
Brain MRI-to-PET Synthesis using 3D Convolutional Attention Networks
Accurate quantification of cerebral blood flow (CBF) is essential for the
diagnosis and assessment of a wide range of neurological diseases. Positron
emission tomography (PET) with radiolabeled water (15O-water) is considered the
gold-standard for the measurement of CBF in humans. PET imaging, however, is
not widely available because of its prohibitive costs and use of short-lived
radiopharmaceutical tracers that typically require onsite cyclotron production.
Magnetic resonance imaging (MRI), in contrast, is more readily accessible and
does not involve ionizing radiation. This study presents a convolutional
encoder-decoder network with attention mechanisms to predict gold-standard
15O-water PET CBF from multi-sequence MRI scans, thereby eliminating the need
for radioactive tracers. Inputs to the prediction model include several
commonly used MRI sequences (T1-weighted, T2-FLAIR, and arterial spin
labeling). The model was trained and validated using 5-fold cross-validation in
a group of 126 subjects consisting of healthy controls and cerebrovascular
disease patients, all of whom underwent simultaneous $15O-water PET/MRI. The
results show that such a model can successfully synthesize high-quality PET CBF
measurements (with an average SSIM of 0.924 and PSNR of 38.8 dB) and is more
accurate compared to concurrent and previous PET synthesis methods. We also
demonstrate the clinical significance of the proposed algorithm by evaluating
the agreement for identifying the vascular territories with abnormally low CBF.
Such methods may enable more widespread and accurate CBF evaluation in larger
cohorts who cannot undergo PET imaging due to radiation concerns, lack of
access, or logistic challenges.Comment: 19 pages, 14 figure
ADAM9 inhibition increases membrane activity of ADAM10 and controls α-secretase processing of amyloid precursor protein
Prodomains of A disintegrin and metalloproteinase (ADAM) metallopeptidases can act as highly specific intra- and intermolecular inhibitors of ADAM catalytic activity. The mouse ADAM9 prodomain (proA9; amino acids 24â204), expressed and characterized from Escherichia coli, is a competitive inhibitor of human ADAM9 catalytic/disintegrin domain with an overall inhibition constant of 280 ± 34 nm and high specificity toward ADAM9. In SY5Y neuroblastoma cells overexpressing amyloid precursor protein, proA9 treatment reduces the amount of endogenous ADAM10 enzyme in the medium while increasing membrane-bound ADAM10, as shown both by Western and activity assays with selective fluorescent peptide substrates using proteolytic activity matrix analysis. An increase in membrane-bound ADAM10 generates higher levels of soluble amyloid precursor protein α in the medium, whereas soluble amyloid precursor protein ÎČ levels are decreased, demonstrating that inhibition of ADAM9 increases α-secretase activity on the cell membrane. Quantification of physiological ADAM10 substrates by a proteomic approach revealed that substrates, such as epidermal growth factor (EGF), HER2, osteoactivin, and CD40-ligand, are increased in the medium of BT474 breast tumor cells that were incubated with proA9, demonstrating that the regulation of ADAM10 by ADAM9 applies for many ADAM10 substrates. Taken together, our results demonstrate that ADAM10 activity is regulated by inhibition of ADAM9, and this regulation may be used to control shedding of amyloid precursor protein by enhancing α-secretase activity, a key regulatory step in the etiology of Alzheimer disease.National Institutes of Health (U.S.) (Grant R01EB010246)National Institutes of Health (U.S.) (Grant R01GM081336)Heptagon Fund (London, England)Cancer Research UKWhitehead FoundationDuke University. School of Medicine (Bridge Funding Program)Germany. Bundesministerium fuÌr Bildung und ForschungChina (National Fellowship from the Chinese Scholarship Council)Florida State Universit
Improved regeneration and de novo bone formation in a diabetic zebrafish model treated with paricalcitol and cinacalcet
Bone changes related to diabetes have been well stablished, but few strategies have been developed to prevent this growing health problem. In our work, we propose to investigate the effects of calcitriol as well as of a vitamin D analog (paricalcitol) and a calcimimetic (cinacalcet), in fin regeneration and de novo mineralization in a zebrafish model of diabetes. Following exposure of diabetic transgenic Tg(ins: nfsb-mCherry) zebrafish to calcitriol, paricalcitol and cinacalcet, caudal fins were amputated to assess their effects on tissue regeneration. Caudal fin mineralized and regenerated areas were quantified by in vivo alizarin red staining. Quantitative real-time PCR was performed using RNA from the vertebral column. Diabetic fish treated with cinacalcet and paricalcitol presented increased regenerated and mineralized areas when compared with non-treated diabetic group, while no significant increase was observed in nondiabetic fish treated with both drugs. Gene expression analysis showed an up-regulation for runt-related transcription factor 2b (runx2b), bone gamma-carboxyglutamic acid-containing protein (bglap), insulin a (insa) and insulin b (insb) and a trend of increase for sp7 transcription factor (sp7) in diabetic groups treated with cinacalcet and paricalcitol. Expression of insra and vdra was up-regulated in both diabetic and nondiabetic fish treated with cinacalcet. In nondiabetic fish treated with paricalcitol and cinacalcet a similar increase in gene expression could be observed but not so pronounced. The increased mineralization and regeneration in diabetic zebrafish treated with cinacalcet and paricalcitol can be explained by increased osteoblastic differentiation and increased insulin expression indicating pro-osteogenic potential of both drugs.European Regional Development Fund (ERDF) through the COMPETE-Operational Competitiveness ProgramFCT-Fundacao para a Ciencia e a Tecnologia [PEst-CCMAR/Multi/04326/2013]info:eu-repo/semantics/publishedVersio
Quantification of cerebral perfusion and cerebrovascular reserve using TurboâQUASAR arterial spin labeling MRI
PurposeTo compare cerebral blood flow (CBF) and cerebrovascular reserve (CVR) quantification from TurboâQUASAR (quantitative signal targeting with alternating radiofrequency labeling of arterial regions) arterial spin labeling (ASL) and single postâlabeling delay pseudoâcontinuous ASL (PCASL).MethodsA modelâbased method was developed to quantify CBF and arterial transit time (ATT) from TurboâQUASAR, including a correction for magnetization transfer effects caused by the repeated labeling pulses. Simulations were performed to assess the accuracy of the modelâbased method. Data from an in vivo experiment conducted on a healthy cohort were retrospectively analyzed to compare the CBF and CVR (induced by acetazolamide) measurement from TurboâQUASAR and PCASL on the basis of global and regional differences. The quality of the two ASL data sets was examined using the coefficient of variation (CoV).ResultsThe modelâbased method for TurboâQUASAR was accurate for CBF estimation (relative error was 8% for signalâtoânoise ratio = 5) in simulations if the bolus duration was known. In the in vivo experiment, the mean global CVR estimated by TurboâQUASAR and PCASL was between 63% and 64% and not significantly different. Although global CBF values of the two ASL techniques were not significantly different, regional CBF differences were found in deep gray matter in both preâ and postacetazolamide conditions. The CoV of TurboâQUASAR data was significantly higher than PCASL.ConclusionBoth ASL techniques were effective for quantifying CBF and CVR, despite the regional differences observed. Although CBF estimated from TurboâQUASAR demonstrated a higher variability than PCASL, TurboâQUASAR offers the advantage of being able to measure and control for variation in ATT
Synthesis of anthraquinone based electroactive polymers: A critical review
Conducting polymers or synthetic monomers have revolutionized the world and are at the heart of scientific research having a scope of vast diverse applications in many technological fields. The conducting and redox polymers have been investigated as energy storage systems because of their better sustainability, ease of synthesis, and environmental compatibility. Owing to the conducting properties of quinones, they gain too much importance among the researchers. Keeping in view the importance and sustainability of conducting polymers, for the first time, this study compiles a detailed overview of synthetic approaches followed by investigations on electrochemical properties and future directions. This study critically examines the synthetic process of simple monomers, substituted monomers, and polymers of anthraquinone (AQ) under the classification of low- and high-molecular-weight AQâbased derivatives, their working principles, and their electrochemical applications, which enable us to explore their novel possible application in automotive, solar cell devices, aircraft aileron, and biomedical equipment. Irrefutably, we confirm that high-molecular-weight polymeric AQ compounds are best in comparison with low-molecular-weight AQ monomers because they have pre-eminent properties over monomeric systems. Because of the significant properties of AQ, polymeric systems are high demanding and have emerged as a hot topic among the researchers these days. In the current scenario, this study is of immense importance because it identifies and discusses the right and sustainable combination and paves the way to utilize these novel materials in different technologies
Starspots due to large-scale vortices in rotating turbulent convection
We study the generation of large-scale vortices in rotating turbulent
convection by means of Cartesian direct numerical simulations. We find that for
sufficiently rapid rotation, cyclonic structures on a scale large in comparison
to that of the convective eddies, emerge, provided that the fluid Reynolds
number exceeds a critical value. For slower rotation, cool cyclonic vortices
are preferred, whereas for rapid rotation, warm anti-cyclonic vortices are
favored. In some runs in the intermediate regime both types of cyclones
co-exist for thousands of convective turnover times. The temperature contrast
between the vortices and the surrounding atmosphere is of the order of five per
cent. We relate the simulation results to observations of rapidly rotating
late-type stars that are known to exhibit large high-latitude spots from
Doppler imaging. In many cases, cool spots are accompanied with spotted regions
with temperatures higher than the average. In this paper, we investigate a
scenario according to which the spots observed in the temperature maps could
have a non-magnetic origin due to large-scale vortices in the convection zones
of the stars.Comment: 8 pages, 8 figures, version published in ApJ. Version with higher
resolution figures can be found at http://www.helsinki.fi/~kapyla/publ.htm
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