155 research outputs found
An interesting example for spectral invariants
In "Illinois J. of Math. {\bf 38} (1994) 653--678", the heat operator of a
Bismut superconnection for a family of generalized Dirac operators is defined
along the leaves of a foliation with Hausdorff groupoid. The Novikov-Shubin
invariants of the Dirac operators were assumed greater than three times the
codimension of the foliation. It was then showed that the associated heat
operator converges to the Chern character of the index bundle of the operator.
In "J. K-Theory {\bf 1} (2008) 305--356", we improved this result by reducing
the requirement on the Novikov-Shubin invariants to one half of the
codimension. In this paper, we construct examples which show that this is the
best possible result.Comment: Third author added. Some typos corrected and some material added.
Appeared in Journal of K Theory, Volume 13, in 2014, pages 305 to 31
Exosomes and their Cargo as a New Avenue for Brain and Treatment of CNSRelated Diseases
Extracellular Vesicles (EVs), which belong to nanoscale vesicles, including microvesicles (MVs) and exosomes, are now considered a new important tool for intercellular neuronal communication in the Central Nervous System (CNS) under physiological and pathological conditions. EVs are shed into blood, peripheral body fluids and cerebrospinal fluid (CSF) by a large variety of cells. EVs can act locally on neighboring and distant cells. EVs represent the fingerprints of the originating cells and can carry a variety of molecular constituents of their cell of origin, including protein, lipids, DNA and microRNAs (miRNAs). The most studied EVs are the exosomes because they are ubiquitous and have the capacity to transfer cell-derived components and bioactive molecules to target cells. In this minireview, we focused on cell-cell communication in CNS mediated by exosomes and their important cargo as an innovative way to treat or follow up with CNS diseases. © 2022 Benameur et al
Extracellular vesicles miRNA cargo for microglia polarization in traumatic brain injury
Traumatic brain injury (TBI) is one of the major causes of death and disability worldwide, and despite its high dissemination, effective pharmacotherapies are lacking. TBI can be divided into two phases: the instantaneous primary mechanical injury, which occurs at the moment of insult, and the delayed secondary injury, which involves a cascade of biological processes that lead to neuroinflammation. Neuroinflammation is a hallmark of both acute and chronic TBI, and it is considered to be one of the major determinants of the outcome and progression of disease. In TBI one of the emerging mechanisms for cellâcell communication involved in the immune response regulation is represented by Extracellular Vesicles (EVs). These latter are produced by all cell types and are considered a fingerprint of their generating cells. Exosomes are the most studied nanosized vesicles and can carry a variety of molecular constituents of their cell of origin, including microRNAs (miRNAs). Several miRNAs have been shown to target key neuropathophysiological pathways involved in TBI. The focus of this review is to analyze exosomes and their miRNA cargo to modulate TBI neuroinflammation providing new strategies for prevent longâterm progression of disease
L^2 rho form for normal coverings of fibre bundles
We define the secondary invariants L^2- eta and -rho forms for families of
generalized Dirac operators on normal coverings of fibre bundles. On the
covering family we assume transversally smooth spectral projections, and
Novikov--Shubin invariants bigger than 3(dim B+1) to treat the large time
asymptotic for general operators. In the particular case of a bundle of spin
manifolds, we study the L^2- rho class in relation to the space of positive
scalar curvature vertical metrics.Comment: 21 pages, revised versio
The emerging role of curcumin in the modulation of TLR-4 signaling pathway: Focus on neuroprotective and anti-rheumatic properties
Natural products have been used in medicine for thousands of years. Given their potential health benefits, they have gained significant popularity in recent times. The administration of phytochemicals existed shown to regulate differential gene expression and modulate various cellular pathways implicated in cell protection. Curcumin is a natural dietary polyphenol extracted from Curcuma Longa Linn with different biological and pharmacological effects. One of the important targets of curcumin is Toll-like receptor-4 (TLR-4), the receptor which plays a key role in the modulation of the immune responses and the stimulation of inflammatory chemokines and cytokines production. Different studies have demonstrated that curcumin attenuates inflammatory response via TLR-4 acting directly on receptor, or by its downstream pathway. Curcumin bioavailability is low, so the use of exosomes, as nano drug delivery, could improve the efficacy of curcumin in inflammatory diseases. The focus of this review is to explore the therapeutic effect of curcumin interacting with TLR-4 receptor and how this modulation could improve the prognosis of neuroinflammatory and rheumatic diseases
Impact strength of composites with nano-enhanced resin after fire exposure
Composite materials have been widely used in several engineering applications. However, there are very few studies about the effects of nanoclays on the impact strength of laminates after exposure to the fire. Therefore, this paper intends to study this subject and the impact performance was analysed by low velocity impact tests carried out at different incident impact energy levels. For better dispersion and interface adhesion matrix/clay, nanoclays were previously subjected to a silane treatment appropriate to the epoxy resin. The exposure to the fire decreases the maximum load and increases the displacement in comparison with the respective values obtained at room temperature. Mathematical relationships are proposed to estimate the maximum impact force and displacement, based on the total impact energy and flexural stiffness. Finally, a decrease of the elastic recuperation can be found, independently of the benefits introduced by the nanoclays
Curcumin as prospective anti-aging natural compound: Focus on brain
The nutrients and their potential benefits are a new field of study in modern medicine for their positive impact on health. Curcumin, the yellow polyphenolic compound extracted from Curcuma longa species, is widely used in traditional Ayurvedic medicine to prevent and contrast many diseases, considering its antioxidant, immunomodulatory, anti-inflammatory, anti-microbial, cardio-protective, nephron-protective, hepato-protective, anti-neoplastic, and anti-rheumatic proprieties. In recent years, the investigations of curcumin have been focused on its application to aging and age-associated diseases. Aging is a physiological process in which there is a decreasing of cellular function due to internal or external stimuli. Oxidative stress is one of the most important causes of aging and age-related diseases. Moreover, many age-related disorders such as cancer, neuroinflammation, and infections are due to a low-grade chronic systemic inflammation. Curcumin acting on different proteins is able to contrast both oxidative stress than inflammation. In the brain, curcumin is able to modulate inflammation induced by microglia. Finally in brain tumors curcumin is able to reduce tumor growth by inhibition of telomerase activity. This review emphasizes the anti-aging role of curcumin focusing on its mechanism to counteract aging in the brain. Moreover, new formulations to increase the bioavailability of curcumin are discussed
Microparticles from patients with metabolic syndrome induce in vivo vascular hypo-reactivity via Fas/Fas-Ligand pathway by increasing oxidative and nitrosative stresses in mouse aorta
Microparticles from patients with metabolic syndrome induce vascular hypo-reactivity via Fas/Fas-Ligand pathway in mice
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