1,275 research outputs found
MMsPred: a bioactivity and toxicology predictive system
In the last decade, the development and use of new methods in combinatorial chemistry and high-throughput screening has dramatically increased the number of known biologically active compounds. Paradoxically, the number of drugs reaching the market has not followed the same trend, often because many of the candidate drugs present poor qualities in absorption, distribution, metabolism, excretion, and toxicological properties (ADME-Tox). The ability to recognize and discard bad candidates early in the drug discovery steps would save lost investments in time and money. Machine learning techniques could provide solutions to this problem.
The goal of my research is to develop classifiers that accurately discriminate between active and inactive molecules for a specific target. To this end, I am comparing the effectiveness of the application of different machine learning techniques to this problem.	As a source of data we have selected a set of PubChem's public BioAssays1. In addition, with the objective of realizing a real-time query service with our predictors, we aim to keep the features describing the chemical compounds relatively simple.
At the end of this process, we should better understand how to build statistical models that are able to recognize molecules active in a specific bioassay, including how to select the most appropriate classification technique, and how to describe compounds in such a way that is not excessively resource-consuming to generate, yet contains sufficient information for the classification. We see immediate applications of such technology to recognize compounds with high-risk of toxicity, and also to suggest likely metabolic pathways that would process it
How does a dark compact object ringdown?
A generic feature of nearly out-of-equilibrium dissipative systems is that
they resonate through a set of quasinormal modes. Black holes - the absorbing
objects par excellence - are no exception. When formed in a merger, black holes
vibrate in a process called "ringdown", which leaves the gravitational-wave
footprint of the event horizon. In some models of quantum gravity which attempt
to solve the information-loss paradox and the singularities of General
Relativity, black holes are replaced by regular, horizonless objects with a
tiny effective reflectivity. Motivated by these scenarios, here we develop a
generic framework to the study of the ringdown of a compact object with various
shades of darkness. By extending the black-hole membrane paradigm, we map the
interior of any compact object in terms of the bulk and shear viscosities of a
fictitious fluid located at the surface, with the black-hole limit being a
single point in a three-dimensional parameter space. We unveil some remarkable
features of the ringdown and some universal properties of the light ring in
this framework. We also identify the region of the parameter space which can be
probed by current and future gravitational-wave detectors. A general feature is
the appearance of mode doublets which are degenerate only in the black-hole
limit. We argue that the merger event GW150914 already imposes a strong lower
bound on the compactness of the merger remnant of approximately 99% of the
black-hole compactness. This places model-independent constraints on black-hole
alternatives such as diffuse "fuzzballs" and nonlocal stars.Comment: 11+7 pages, 8 figures. v2: minor revisions to match the version to
appear in PR
How time window influences biometrics performance: an EEG-based fingerprints connectivity study
EEG-based biometric represents a relatively recent research field that aims
to recognize individuals based on their recorded brain activity by means of
electroencephalography (EEG). Among the numerous features that have been
proposed, connectivity-based approaches represent one of the more promising
methods tested so far. In this paper, we investigate how the performance of an
EEG biometric system varies with respect to different time windows to
understand if it is possible to define the optimal duration of EEG signal that
can be used to extract those distinctive features. Overall, the results have
shown a pronounced effect of the time window on the biometric performance
measured in terms of EER (equal error rate) and AUC (area under the curve),
with an evident increase of the biometric performance with an increase of the
time window. In conclusion, we want to highlight that EEG connectivity has the
potential to represent an optimal candidate as EEG fingerprint and that, in
this context, it is very important to define a sufficient time window able to
collect the subject specific features. Moreover, our preliminary results show
that extending the window size beyond a certain maximum does not improve
biometric systems' performance
The Evolution of Primordial Black Holes and their Final Observable Spins
Primordial black holes in the mass range of ground-based gravitational-wave
detectors can comprise a significant fraction of the dark matter. Mass and spin
measurements from coalescences can be used to distinguish between an
astrophysical or a primordial origin of the binary black holes. In standard
scenarios the spin of primordial black holes is very small at formation.
However, the mass and spin can evolve through the cosmic history due to
accretion. We show that the mass and spin of primordial black holes are
correlated in a redshift-dependent fashion, in particular primordial black
holes with masses below are likely non-spinning at any
redshift, whereas heavier black holes can be nearly extremal up to redshift
. The dependence of the mass and spin distributions on the redshift
can be probed with future detectors such as the Einstein Telescope. The mass
and spin evolution affect the gravitational waveform parameters, in particular
the distribution of the final mass and spin of the merger remnant, and that of
the effective spin of the binary. We argue that, compared to the
astrophysical-formation scenario, a primordial origin of black hole binaries
might better explain the spin distribution of merger events detected by
LIGO-Virgo, in which the effective spin parameter of the binary is compatible
to zero except possibly for few high-mass events. Upcoming results from
LIGO-Virgo third observation run might reinforce or weaken these predictions.Comment: 13 figures, 31 pages. v2: Section and appendix added. Results
unchange
Predictors of response to erenumab after 12 months of treatment
Objective: Erenumab is a monoclonal antibody acting against calcitonin gene-related peptide receptor and approved for the preventive treatment of chronic migraine. The aim of the present study is to identify clinical predictors of good response in patients with chronic migraine and medication overuse-headache. Material and methods: This was a retrospective single-center not funded study. Enrolled patients were affected by chronic migraine and medication overuse-headache treated with erenumab monthly, up to 1 year. At 1 year, patients were classified as good responders if they displayed a ≥50% reduction in the number of headache days per months compared to the baseline. Results: After 1 year, a significant improvement in the number of headache days per months, analgesic consumption, 6-items headache impact test, and migraine disability assessment questionnaire scores were obtained compared to the baseline. Patients who obtained a ≥50% reduction in the number of headache days per month compared to the baseline displayed a longer history of medication overuse-headache, a higher number of painkillers taken per month at the baseline and a higher number of failed preventive treatments in the past. Conclusions: Patients with longer medication overuse-headache duration, higher analgesic intake, and a higher number of previous preventive treatment failures may receive less benefit with erenumab
Novel epigenetic target therapy for prostate cancer: a preclinical study.
Epigenetic events are critical contributors to the pathogenesis of cancer, and targeting epigenetic mechanisms represents a novel strategy in anticancer therapy. Classic demethylating agents, such as 5-Aza-29-deoxycytidine (Decitabine), hold the potential for reprograming somatic cancer cells demonstrating high therapeutic efficacy in haematological malignancies. On the other hand, epigenetic treatment of solid tumours often gives rise to undesired cytotoxic side effects. Appropriate delivery systems able to enrich Decitabine at the site of action and improve its bioavailability would reduce the incidence of toxicity on healthy tissues. In this work we provide preclinical evidences of a safe, versatile and efficient targeted epigenetic therapy to treat hormone sensitive (LNCap) and hormone refractory (DU145) prostate cancers. A novel Decitabine formulation, based on the use of engineered erythrocyte (Erythro-Magneto-Hemagglutinin Virosomes, EMHVs) drug delivery system (DDS) carrying this drug, has been refined. Inside the EMHVs, the drug was shielded from the environment and phosphorylated in its active form. The novel magnetic EMHV DDS, endowed with fusogenic protein, improved the stability of the carried drug and exhibited a high efficiency in confining its delivery at the site of action in vivo by applying an external static magnetic field. Here we show that Decitabine loaded into EMHVs induces a significant tumour mass reduction in prostate cancer xenograft models at a concentration, which is seven hundred times lower than the therapeutic dose, suggesting an improved pharmacokinetics/pharmacodynamics of drug. These results are relevant for and discussed in light of developing personalised autologous therapies and innovative clinical approach for the treatment of solid tumours
Analysis of CYP2D6
The CYP2D6 enzyme is involved in the metabolism of many commonly prescribed drugs. The presence of polymorphisms in the CYP2D6 gene may modulate the enzyme level and activity affecting individual responses, to pharmacological treatment in drug level, response and adverse reactions. Aims. This study aimed to analyze the determination of allele frequencies in Sardinians and the comparison to frequencies found in the Caucasian Population. Methods and Materials. We used a Long PCR strategy coupled to direct genomic DNA sequencing analysis. An amplification allele-specific was carried out to infer the correct allelic phase. The TaqMan Gene Copy Number Assay (Applied Biosystems) was used to verify the presence of gene deletions/multiplications. Results and Conclusions. Our results indicated that CYP2D6 allele frequencies in Sardinians differed from those previously detected in the Caucasian Population. Moreover, three new SNPs and four novel haplotypes were identified
Wandering spleen with a ten-time twisted vascular pedicle
Torsion of a wandering spleen is a rare cause of acute abdomen in children, usually diagnosed with color-Doppler ultrasonography and enhanced computed tomography. We report a pediatric case of torsion of wandering spleen
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