833 research outputs found
Phase coexistence and relaxation of the spherical frustrated Blume-Emery-Griffiths model with attractive particles coupling
We study the equilibrium and dynamical properties of a spherical version of
the frustrated Blume-Emery-Griffiths model at mean field level for attractive
particle-particle coupling (K>0). Beyond a second order transition line from a
paramagnetic to a (replica symmetric) spin glass phase, the density-temperature
phase diagram is characterized by a tricritical point from which,
interestingly, a first order transition line starts with coexistence of the two
phases. In the Langevin dynamics the paramagnetic/spin glass discontinuous
transition line is found to be dependent on the initial density; close to this
line, on the paramagnetic side, the correlation-response plot displays
interrupted aging.Comment: to be published on Europhysics Letter
Brain organoids: Filling the need for a human model of neurological disorder
Neurological disorders are among the leading causes of death worldwide, accounting for almost all onsets of dementia in the elderly, and are known to negatively affect motor ability, mental and cognitive performance, as well as overall wellbeing and happiness. Currently, most neurological disorders go untreated due to a lack of viable treatment options. The reason for this lack of options is s poor understanding of the disorders, primarily due to research models that do not translate well into the human in vivo system. Current models for researching neurological disorders, neurodevelopment, and drug interactions in the central nervous system include in vitro monolayer cell cultures, and in vivo animal models. These models have shortcomings when it comes to translating research about disorder pathology, development, and treatment to humans. Brain organoids are three-dimensional (3D) cultures of stem cell-derived neural cells that mimic the development of the in vivo human brain with high degrees of accuracy. Researchers have started developing these miniature brains to model neurodevelopment, and neuropathology. Brain organoids have been used to model a wide range of neurological disorders, including the complex and poorly understood neurodevelopmental and neurodegenerative disorders. In this review, we discuss the brain organoid technology, placing special focus on the different brain organoid models that have been developed, discussing their strengths, weaknesses, and uses in neurological disease modeling
Glass glass transition and new dynamical singularity points in an analytically solvable p-spin glass like model
We introduce and analytically study a generalized p-spin glass like model
that captures some of the main features of attractive glasses, recently found
by Mode Coupling investigations, such as a glass/glass transition line and
dynamical singularity points characterized by a logarithmic time dependence of
the relaxation. The model also displays features not predicted by the Mode
Coupling scenario that could further describe the attractive glasses behavior,
such as aging effects with new dynamical singularity points ruled by
logarithmic laws or the presence of a glass spinodal line
A Novel Gaussian Extrapolation Approach for 2D Gel Electrophoresis Saturated Protein Spots
Analysis of images obtained from two-dimensional gel electrophoresis (2D-GE) is a topic of utmost importance in bioinformatics research, since commercial and academic software available currently has proven to be neither completely effective nor fully automatic, often requiring manual revision and refinement of computer generated matches. In this work, we present an effective technique for the detection and the reconstruction of over-saturated protein spots. Firstly, the algorithm reveals overexposed areas, where spots may be truncated, and plateau regions caused by smeared and overlapping spots. Next, it reconstructs the correct distribution of pixel values in these overexposed areas and plateau regions, using a two-dimensional least-squares fitting based on a generalized Gaussian distribution. Pixel correction in saturated and smeared spots allows more accurate quantification, providing more reliable image analysis results. The method is validated for processing highly exposed 2D-GE images, comparing reconstructed spots with the corresponding non-saturated image, demonstrating that the algorithm enables correct spot quantification
MicroRNA Roles in Cell Reprogramming Mechanisms
Cell reprogramming is a groundbreaking technology that, in few decades, generated a new paradigm in biomedical science. To date we can use cell reprogramming to potentially generate every cell type by converting somatic cells and suitably modulating the expression of key transcription factors. This approach can be used to convert skin fibroblasts into pluripotent stem cells as well as into a variety of differentiated and medically relevant cell types, including cardiomyocytes and neural cells. The molecular mechanisms underlying such striking cell phenotypes are still largely unknown, but in the last decade it has been proven that cell reprogramming approaches are significantly influenced by non-coding RNAs. Specifically, this review will focus on the role of microRNAs in the reprogramming processes that lead to the generation of pluripotent stem cells, neurons, and cardiomyocytes. As highlighted here, non-coding RNA-forced expression can be sufficient to support some cell reprogramming processes, and, therefore, we will also discuss how these molecular determinants could be used in the future for biomedical purposes
A novel Gaussian fitting approach for 2D gel electrophoresis saturated protein spots
Analysis of 2D-GE images is a hot topic in bioinformatics research, since currently available commercial
and academic software has proven to be not really effective and not completely automatic, often requiring
manual revision of spots detection and refinement of computer generated matches. In this work, we present
an effective technique for the detection and the reconstruction of over-saturated protein spots.
Firstly, it reveals overexposed areas where spots may be truncated, and plateau regions caused by smeared
and overlapped spots. As next, the correct distribution of pixel values in the overexposed areas and plateau
regions is recovered by a two-dimensional fitting based on a generalized Gaussian distribution approximating
the spots volume. Pixel correction according to the generalized Gaussian curve in saturated and smeared
spots allows more accurate quantifications, providing more reliable image analysis results.
As validation, we process highly exposed 2D-GE image, containing saturate spots, with respect to the corresponding
non-saturated image, confirming that the method can effectively fix the saturated spots and enable
correct spots quantification
Small fragments sodium sulfated hyaluronate, more than hyaluronic acid, reduces LPS-induced cytokine/chemokine levels in HaCaT cells
Hyaluronic acid (HA) is a linear non-sulphated glycosaminoglycan, used in dermatology as a
biomaterial for bioengineering purposes, temporary dermal filler, stimulation of wound healing
as well as drug vehicle in topical formulations. In addition to the well-characterized
structural properties, extensive research on HA has revealed a range of vastly immunemodulatory
effects, dependent on its size. In this in vitro study we investigated the ability of
HA-S3, a small fragment HA (MW, molecular weight: 68 kDa) with degree of sulphatation
of 3 and of HA fraction (MW:210 kDa) to reduce the bacterial induced inflammatory response
in spontaneous immortalized keratinocytes. To this purpose, HaCaT cells were treated for
24 hours with 25 ”g/ml of E. Coli derived bacterial lipopolysaccharide (LPS) in absence or
presence of small fragment HA-S3 or HA. Cell viability was thereafter assessed using trypan
blue stain and interleukin (IL)-8, IL-1ÎČ and tumor necrosis factor alpha (TNF-α) concentrations
were determined in cell supernatants by single enzyme-linked immunoadsorbent assay
(ELISA). Our results showed that cell viability was not affected either by HA-S3 or HA which
in turn were able to reduce LPS-induced mortality. HA and especially HA-S3 were able to
significantly reduce LPS-induced pro-inflammatory cytokines. Our observation might suggest
new perspectives in the development of HA-S3 containing topical products able to modulate
cutaneous inflammatory response
Impact of Alkyl Chain Length on the Formation of Regular- and Reverse-Graded Quasi-2D Perovskite Thin Films
Crystallization of low-dimensional perovskites is a complex process that leads to multidimensional films comprising two-dimensional (2D), quasi-2D, and three-dimensional (3D) phases. Most quasi-2D perovskite films possess a regular gradient with 2D phases located at the bottom of the film and 3D phases at the top. Recently, multiple studies have reported reverse-graded perovskite films, where the location of the 2D and 3D structures is inverted. The underlying reasons for such a peculiar phase distribution are unclear. While crystallization of regular-graded quasi-2D perovskites has been described as starting with 3D phases from the liquid-air interface, the film formation of reverse-graded films has not been investigated yet. Here, we examine the impact of the alkyl chain length on the formation of regular- and reverse-graded perovskites using n-alkylammonium ions. We find that long alkyl chains reverse the phase distribution gradient. By combining photoluminescence spectroscopy with in situ optical absorption measurements, we demonstrate that crystallization starts at the liquid-N2 interface, though as 3D phases for short-chain n-alkylammonium ions and as quasi-2D phases for long chains. We link this behavior to enhanced van der Waals interactions between long-chain n-alkylammonium ions in polar solvents and their tendency to accumulate at the liquid-N2 interface, creating a concentration gradient along the film thickness.</p
High resolution chemical stratigraphies of atmospheric depositions from a 4 m depth snow pit at dome C (East Antarctica)
In this work, we present chemical stratigraphies of two sampling lines collected within a 4 m depth snow pit dug in Dome C during the Antarctic summer Campaign 2017/2018, 12 years after the last reported snow pit. The first sampling line was analyzed for nine anionic and cationic species using Ion Chromatography (IC); the second sampling line was analyzed for seven major elements in an innovative way with Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) after sample pre-concentration, allowing the study of deposition processes of new markers especially related to crustal source. This coupled analysis, besides confirming previous studies, allowed us to investigate the depositions of the last decades at Dome C, enriching the number of the detected chemical markers, and yielding these two techniques complementary for the study of different markers in this kind of matrix. As a result of the dating, the snow layers analyzed covered the last 50 years of snow depositions. The assessment of the accumulation rate, estimated about 9 cm yrâ1, was accomplished only for the period 1992â2016, as the eruption of 1992 constituted the only tie-point found in nssSO42â depth profile. Na, the reliable sea salt marker, together with Mg and Sr, mainly arose from marine sources, whereas Ca, Al and Fe originated from crustal inputs. Post-depositional processes occurred on Clâ as well as on NO3â and methanesulfonic acid (MSA); compared to the latter, Clâ had a more gradual decrease, reporting a threshold at 2.5 m for the post-depositional process completion. For NO3â and MSA, instead, the threshold was shallower, at about 1 m depth, with a loss of 87% for NO3â and of 50% for MSA
A Novel Gaussian Extrapolation Approach for 2D Gel Electrophoresis Saturated Protein Spots
Analysis of images obtained from two-dimensional gel electrophoresis (2D-GE) is a topic of utmost importance in bioinformatics research, since commercial and academic software available currently has proven to be neither completely effective nor fully automatic, often requiring manual revision and refinement of computer generated matches. In this work, we present an effective technique for the detection and the reconstruction of over-saturated protein spots. Firstly, the algorithm reveals overexposed areas, where spots may be truncated, and plateau regions caused by smeared and overlapping spots. Next, it reconstructs the correct distribution of pixel values in these overexposed areas and plateau regions, using a two-dimensional least-squares fitting based on a generalized Gaussian distribution. Pixel correction in saturated and smeared spots allows more accurate quantification, providing more reliable image analysis results. The method is validated for processing highly exposed 2D-GE images, comparing reconstructed spots with the corresponding non-saturated image, demonstrating that the algorithm enables correct spot quantificatio
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