1,721,040 research outputs found
New strategies to overcome resistance to chemotherapy and immune system in cancer
Full text linkMultiDrug resistance (MDR) is a complex phenomenon responsible for multiple cross-resistance towards structurally unrelated drugs and it characterizes almost 70% of solid and haematological tumours at the diagnosis [...]
Editorial: The Canonical and Non-Canonical Endocannabinoid System as a Target in Cancer and Acute and Chronic Pain
Full text linkEditorial pape
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Perspectives of Cannabinoid Type 2 Receptor (CB2R) Ligands in Neurodegenerative Disorders: Structure–Affinity Relationship (SAfiR) and Structure–Activity Relationship (SAR) Studies
Full text linkUp-regulation of CB2R on activated microglial cells, the first step in neurodegeneration, has been widely demonstrated, and this finding makes the receptor a promising target in the early diagnosis and treatment of several neurodegenerative disorders such as Alzheimer’s disease (AD), Parkinson’s disease (PD), Huntington’s disease (HD), and multiple sclerosis (MS). The development of CB2R PET ligands could help demonstrate the neurodegenerative pathogenesis,
thus providing useful tools for characterizing the role of neuroinflammation in the progression of these disorders.
CB2R agonists and inverse agonists have emerged as neuroprotective agents, and CB2R agonists have entered several clinical trials. CB2R ligands have therefore received great attention, and different molecular scaffolds have been selected to target CB2R subtypes. This review is focused on structure−activity relationship (SAR) and structure−affinity relationship (SAfiR) studies performed on different scaffolds with the aim to identify the molecular features useful for the design of both therapeutic and diagnostic agents
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
P-Glycoprotein, a biological and medicinal chemistry/radiochemistry point of view
No full textP-glycoprotein is an important transporter belonging to ATP-Binding Cassette pumps (ABC-B1). This transporter plays a fundamental role in several degenerative diseases such as Alzheimer's, Parkinson's and other forms of dementia, as well as in tumors. This transporter is localized at the blood brain barrier (BBB) where it is involved in the efflux of endogenous and exogenous compounds and it is overexpressed in several tumor cell lines determining Multi Drug Resistance (MDR). In this chapter, we will examine the in vitro biological assays useful to establish the P-gp interactive mechanisms of a ligand and its potential in terms of therapy and diagnosis. In addition, examples of Structure Activity Relationship (SAR) studies of P-gp modulators will be described. Moreover, P-gp imaging by PET with different radioligands (11C and 18F -radiolabelled) will be herein discussed. Finally, the difficulty in the definition of a pharmacophore for the design of substrates, modulators and inhibitors is also critically approached in this chapter
Influence of morpho-structural parameters on environmental stress cracking in polyethylene
Full text linkPolyethylene (PE) is widely utilized in several industries due to its versatility and mechanical strength, yet its long-term performance is often hindered by slow crack growth (SCG) and environmental stress cracking (ESC). This study quantitatively evaluates the influence of key morpho-structural parameters on SCG and ESC resistance in PE, using a linear elastic fracture mechanics (LEFM) approach to assess the effect of different comonomers on fracture toughness. Four PE materials were analyzed: two medium molecular weight, linear low-density polyethylenes (LLDPE) co-polymerized with 1-butene (Material A) and 1-hexene (Material B); a high molecular weight LLDPE copolymerized with 1-hexene (Material C); and a medium molecular weight, high-density polyethylene (HDPE) homopolymer (Material D). The results confirm that molecular weight is a dominant factor in enhancing stress cracking resistance, with the high molecular weight LLDPE (Material C) showing superior performance. Moreover, despite nearly identical structural parameters, Material B exhibited significantly higher SCG and ESC resistance compared to Material A, highlighting the critical role of the commoner type. The research identified three distinct environmental regimes influencing fracture behavior, each dependent on the applied stress intensity factor (K) and material properties. These regimes are: (1) no significant environmental effect at high K values, where fracture is dominated by the material's inherent properties; (2) partial plasticization of craze fibrils at intermediate K values, due to limited diffusion of environmental agents into the crack tip; and (3) full plasticization of craze fibrils at low K values, where extensive diffusion accelerates environmental stress cracking (ESC). By demonstrating how morpho-structural parameters and environmental conditions together influence polyethylene's resistance to SCG and ESC, this study improves our understanding of the underlying mechanisms and underscores the effectiveness of LEFM in evaluating long-term material performance. This knowledge can guide the design with polyethylene materials aimed at improving long-term durability for industrial applications
Microalgal biomass as renewable biofiller in natural rubber compounds
Full text linkMicroalgal biomasses, consisting of micronized Spirulina Platensis and its low protein fraction, were investigated in this work as possible renewable biofillers in natural rubber compounds, with the aim of replacing the commonly used carbon black. Natural rubber, in some cases blended with 10% of epoxidized natural rubber to improve the matrix-filler affinity, was compounded with 25, 35, 50 and 75 phr of each biomass. Compounds with 25, 35 and 50 phr of carbon black N990 were also prepared as benchmarks. After compounding, vulcanization times were determined by dynamic mechanical analysis. Rubbers were vulcanized by compression moulding and characterized by means of morphological analysis (scanning electron microscopy), thermal analysis (thermogravimetric analysis, dynamic mechanical thermal analysis) and mechanical tests (tensile tests, strain induced crystallization detection by X-ray diffraction, pure shear fracture tests). Microalgal biomass turned out to be homogeneously dispersed in natural rubber matrix and the materials obtained required lower curing times compared to carbon black compounds. It was found that, up to 50 phr, Spirulina has the ability to increase rubber tensile strength and modulus, acting similarly to N990, while decreasing rubber thermal stability and fracture toughness
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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