Totally asymmetric exclusion process with site-wise dynamic disorder

We propose an extension of the totally asymmetric simple exclusion process (TASEP) in which particles hopping along a lattice can be blocked by obstacles that dynamically attach/detach from lattice sites. The model can be thought as TASEP with site-wise dynamic disorder. We consider two versions of defect dynamics: (i) defects can bind to any site, irrespective of particle occupation, (ii) defects only bind to sites which are not occupied by particles (particle-obstacle exclusion). In case (i) there is a symmetric, parabolic-like relationship between the current and particle density, as in the standard TASEP. Case (ii) leads to a skewed relationship for slow defect dynamics. We also show that the presence of defects induces particle clustering, despite the translation invariance of the system. For open boundaries the same three phases as for the standard TASEP are observed, albeit the position of phase boundaries is affected by the presence of obstacles. We develop a simple mean-field theory that captures the model's quantitative behaviour for periodic and open boundary conditions and yields good estimates for the current-density relationship, mean cluster sizes and phase boundaries. Lastly, we discuss an application of the model to the biological process of gene transcription.Comment: submitted to J. Phys.

Relationship between schizophrenia and tobacco smoking - literature analysis

Introduction: There is common statement, that schizophrenia patients are more likely to smoke comparing to the total world population. The aim of the study: The aim of this article is to find out why do schizophrenic patients smoke, how does it affect them and what can be the cause of susceptibility to smoking. Material and method: The research of the scientific articles was made on a database of PubMed and Google Scholar. Description of the state of knowledge: Many different associations were found during the research such as these describing that patients with schizophrenia have up to two to five times higher risk of developing type II diabetes. Also patients with diagnosed schizophrenia are characterized by low neuronal activity of the frontal and temporal lobes of the brain. In post mortem studies in schizophrenic patients a decrease in the number of M1 and M2 receptors in the brain was found, mainly in the dorsal lateral part of the prefrontal cortex, hippocampus, striatum and cingulate cortex, and decreased number of nicotinic receptors in the hippocampus, thalamus, cingulate cortex and prefrontal cortex The key process of undergoing of nicotine is the induction of the cytochrome P450 1A2 enzyme (CYP 1A2), thus increasing the metabolism of antipsychotic therapeutics, e.g. olanzapine, clozapine what explain why usage of nicotine is told to be self-treatment in schizophrenic people. Summary: This article gathers scientific research on the relationship between schizophrenia and susceptibility among patients to smoking addiction and its impact on both mental and physical health. However, not all mechanisms are known yet

Quantitative analysis questions the role of MeCP2 as a global regulator of alternative splicing

MeCP2 is an abundant protein in mature nerve cells, where it binds to DNA sequences containing methylated cytosine. Mutations in the MECP2 gene cause the severe neurological disorder Rett syndrome (RTT), provoking intensive study of the underlying molecular mechanisms. Multiple functions have been proposed, one of which involves a regulatory role in splicing. Here we leverage the recent availability of high-quality transcriptomic data sets to probe quantitatively the potential influence of MeCP2 on alternative splicing. Using a variety of machine learning approaches that can capture both linear and non-linear associations, we show that widely different levels of MeCP2 have a minimal effect on alternative splicing in three different systems. Alternative splicing was also apparently indifferent to developmental changes in DNA methylation levels. Our results suggest that regulation of splicing is not a major function of MeCP2. They also highlight the importance of multi-variate quantitative analyses in the formulation of biological hypotheses

Interactions between asthma and the COVID-19 pandemic

ABSTRACT Introduction: The COVID-19 pandemic has been accompanying us in our daily lives for more than 2.5 years and so far there are no indications that it will leave us soon. Updating information and knowledge about it is therefore still incredibly important. Sars-CoV-2 is a virus with a high affinity for the respiratory system, so it is worth tracing its correlations with one of the more common lung diseases, asthma. Patients with this disease are concerned about whether they are at risk of contracting COVID-19 more frequently and severely, whether they face a higher risk of death if infected and how the pandemic will affect exacerbations of their underlying disease. For physicians who encounter the virus on a daily basis, it is important to know how well to manage asthmatic patients if COVID-19 is confirmed in them. State of knowledge: In medicine, not everything is clear-cut. Much depends on our patient's age, condition and other comorbidities. And also on his/her adherence to medical advice, type and degree of asthma control. In this article, we will address all these aspects and summarise the current knowledge on the interplay between COVID-19 and asthma. Conclusions: With the review of recent reports collected here, it can be thought that asthma is not an independent factor for either a higher frequency or severity of COVID-19, but neither does it affect the higher risk of death with Sars-CoV-2 infection. In terms of treatment, it is important not to interrupt the current therapy and to maintain good asthma control. This is the most optimal treatment and reduces the risk of severe COVID-19. Drugs registered for the treatment of asthma are safe and, moreover, it has been suggested that corticosteroids protect against infection to some extent

Autofluorescence in eleocytes of some earthworm species.

Immunocompetent cells of earthworms, coelomocytes, comprise adherent amoebocytes and granular eleocytes (chloragocytes). Both cell populations can be expelled via dorsal pores of adult earthworms by exposure to an electric current (4.5 V) for 1 min. Analysis by phase contrast/fluorescence microscopy and flow cytometry demonstrated that eleocyte population of several species exhibits a strong autofluorescence. A high percentage (11-35%) of autofluorescent eleocytes was recorded in Allolobophora chlorotica, Dendrodrilus rubidus, Eisenia fetida, and Octolasion sp. (O. cyaneum, O. tyrtaeum tyrtaeum and O. tyrtaeum lacteum). In contrast, autofluorescent coelomocytes were exceptionally scarce (less than 1%) in representative Aporrectodea sp. (A. caliginosa and A. longa) and Lumbricus sp. (L. castaneus, L. festivus, L. rubellus, L. terrestris). Thus, this paper for the first time describes profound intrinsic fluorescence of eleocytes in some--but not all--earthworm species. The function (if any) and inter-species differences of the autofluorescent coelomocytes still remain elusive

Selected physico-chemical properties of composite scaffolds of sintered submicrocrystalline corundum and bioglass

Presented paper contains description and interpretation of the results of selected physicochemical and structural properties of two types of composite sinters. They were constituted of a mixture of sintered microcrystalline corundum and bioglass CaO-P2O5-SiO2-Na2O system intended for scaffolds to cell culture of human chondrocytes. The composites contained a mixture of both above-mentioned components in the volumetric proportion of 50:50 (W5) and 30:70 (W7). They were obtained using powder metallurgy by free sintering in air atmosphere. Phase analysis of composites and verification of theoretical identification using X-ray diffraction were performed. The same phases were found in both cases (Al2O3 SiO2 CaAl2Si2O8, Ca3 (PO4)2, Ca2Al4O7 and NaAlSiO4). Microscopic tests of composite surfaces were performed and some differences were found. W5 sample was not completely covered with bioglass, whilst W7 sample was completely covered with bioglass with few fine pores. Tests of surface topography confirmed the presence of large and small pores. Composite surfaces immersed for 30 days in artificial blood plasma were tested and then electron microscopy analysis was performed. It was found that no significant changes occurred on the surface of the W5 composite, probably partial corrosion of the glass happened. Spherical forms characteristic of HA-hydroxyapatites were observed on the surface of sample W7. Human articular chondrocyte cells were seeded on both types of sinters and proliferation assay was performed. Results indicate that tested scaffolds support cellular attachment and proliferation of chondrocytes

SALL4 controls cell fate in response to DNA base composition

Contains fulltext : 232790.pdf (Publisher’s version ) (Open Access

An Orphan CpG Island Drives Expression of a let-7 miRNA Precursor with an Important Role in Mouse Development.

Most human genes are associated with promoters embedded in non-methylated, G + C-rich CpG islands (CGIs). Not all CGIs are found at annotated promoters, however, raising the possibility that many serve as promoters for transcripts that do not code for proteins. To test this hypothesis, we searched for novel transcripts in embryonic stem cells (ESCs) that originate within orphan CGIs. Among several candidates, we detected a transcript that included three members of the let-7 micro-RNA family: Let-7a-1, let-7f-1, and let-7d. Deletion of the CGI prevented expression of the precursor RNA and depleted the included miRNAs. Mice homozygous for this mutation were sub-viable and showed growth and other defects. The results suggest that despite the identity of their seed sequences, members of the let-7 miRNA family exert distinct functions that cannot be complemented by other members