Testing feasibility of scalar-tensor gravity by scale dependent mass and coupling to matter

We investigate whether there are any cosmological evidences for a scalar field with a mass and coupling to matter which change accordingly to the properties of the astrophysical system it "lives in", without directly focusing on the underlying mechanism that drives the scalar field scale-dependent properties. We assume a Yukawa type of coupling between the field and matter and also that the scalar field mass grows with density, in order to overcome all gravity constraints within the solar system. We analyse three different gravitational systems assumed as "cosmological indicators": supernovae type Ia, low surface brightness spiral galaxies and clusters of galaxies. Results show that: a) a quite good fit to the rotation curves of low surface brightness galaxies only using visible stellar and gas mass components is obtained; b) a scalar field can fairly well reproduce the matter profile in clusters of galaxies, estimated by X-ray observations and without the need of any additional dark matter; c) there is an intrinsic difficulty in extracting information about the possibility of a scale-dependent massive scalar field (or more generally about a varying gravitational constant) from supernovae type Ia.Comment: 30 pages, 15 figures, to appear in Phys. Rev.

Vitamin d in the prevention, development and therapy of oncological diseases

Vitamin D, traditionally known as a fat-soluble essential vitamin, is a precursor of a powerful steroid hormone that regulates a broad spectrum of physiological processes. In addition to its fundamental role in bone metabolism, epidemiological, preclinical and cellular researches in recent decades have revealed that vitamin D can play a considerable role in the prevention of some pathologies, including extra-skeletal ones, such as neoplasms. Vitamin D, as a prohormone, undergoes first hepatic and subsequently renal metabolism to produce a biologically active metabolite, calcitriol or 1α,25-dihydroxyvitamin D or (1,25 (OH)2D), which binds the vitamin D receptor by regulating the expression of several genes involved in bone metabolism and other biological functions. Furthermore, recent studies have revealed that vitamin D can be also metabolized and activated through a non-canonical metabolic pathway catalyzed by CYP11A1, the gene encoding the cholesterol side chain cleavage enzyme or P450scc. The metabolites of vitamin D deriving from the CYP11A1 enzyme have shown antiproliferative and anti-inflammatory activities and are able to promote the differentiation process on neoplastic cells in comparable way or better than calcitriol, thus contributing to its tumor preventive effect. Clinical data have demonstrated that vitamin D has anticancer activity against prostate, colon, and breast cancers. Several molecular mechanisms of vitamin D involved in tumor etiopathogenesis have been proposed that have not yet been fully clarified. Vitamin D may play a key role in preventing the early stage of the neoplastic process by exerting anti-inflammatory, antioxidant defenses and inducing enzymes responsible for repairing DNA damage and could also be involved in mechanisms of inhibition of cell proliferation, induction of cell differentiation, and cell death. In addition, some studies indicate various mechanisms through which vitamin D can quantitatively and qualitatively influence the intestinal microbiota, strongly linked to chronic inflammatory bowel diseases and the development of colon cancer. However, the metabolism and functions of vitamin D are dysregulated in some neoplasms which therefore develop resistance to the antiproliferative effect of vitamin D, and this promotes tumor development and progression. In this review, studies regarding vitamin D in relation to its activity in cancer have been summarized, as long as the metabolic pathways described for vitamin D

Do olfactory and gustatory psychophysical scores have prognostic value in COVID-19 patients? A prospective study of 106 patients

Background: The lack of objective data makes it difficult to establish the prognostic value of chemosensitive disorders in coronavirus disease 2019 (COVID-19) patients. We aimed to prospectively monitor patients diagnosed with COVID-19 to see if the severity of olfactory and gustatory dysfunction associates with subsequent disease severity. Methods: Multicentre prospective study that recruited 106 COVID-19 subjects at diagnosis. Chemosensitive functions were assessed with psychophysical tests within 4 days of clinical onset, at 10 and 20 days. Daily body temperature and oxygen saturation were recorded as markers of disease severity alongside need for hospitalisation. The correlation between olfactory and gustatory scores and disease severity was assessed with linear regression analysis. Results: At T0, 71 patients (67%) presented with olfactory dysfunction while gustatory impairment was detected in 76 cases (65.6%). Chemosensitive disorders gradually improved over the observation period. No significant correlations were found between T0 chemosensitive scores and final disease severity. The correlation between olfactory scores and fever proved significant at T2 (p = 0.05), while the relationship with gustatory scores was significant at T1 (p = 0.01) and T2 (p < 0.001), however neither was clinically relevant. The correlation between chemosensitive scores and oxygen saturation was significant only for taste at T2 (p < 0.001). Logistic regression analysis found significant correlations between olfactory impairment severity and need for hospitalization at T2 (OR 3.750, p = 0.005). Conclusions: Initial objective olfactory and gustatory scores do not seem to have a significant prognostic value in predicting the severity of the COVID-19 course; however, persistence of olfactory dysfunction at 20 days, associated with a more severe course. Unfortunately, olfactory and gustatory dysfunction do not seem to hold prognostic value at the time of initial diagnosis

The Abnormally Weighting Energy Hypothesis: the Missing Link between Dark Matter and Dark Energy

We generalize tensor-scalar theories of gravitation by the introduction of an abnormally weighting type of energy. This theory of tensor-scalar anomalous gravity is based on a relaxation of the weak equivalence principle that is now restricted to ordinary visible matter only. As a consequence, the convergence mechanism toward general relativity is modified and produces naturally cosmic acceleration as an inescapable gravitational feedback induced by the mass-variation of some invisible sector. The cosmological implications of this new theoretical framework are studied. From the Hubble diagram cosmological test \textit{alone}, this theory provides an estimation of the amount of baryons and dark matter in the Universe that is consistent with the independent cosmological tests of Cosmic Microwave Background (CMB) and Big Bang Nucleosynthesis (BBN). Cosmic coincidence is naturally achieved from a equally natural assumption on the amplitude of the scalar coupling strength. Finally, from the adequacy to supernovae data, we derive a new intriguing relation between the space-time dependences of the gravitational coupling and the dark matter mass, providing an example of crucial constraint on microphysics from cosmology. This glimpses at an enticing new symmetry between the visible and invisible sectors, namely that the scalar charges of visible and invisible matter are exactly opposite.Comment: 24 pages, 6 figures, new version with extended discussions and added references. Accepted for publication in JCAP (sept. 2008

Phase Transitions on Nonamenable Graphs

We survey known results about phase transitions in various models of statistical physics when the underlying space is a nonamenable graph. Most attention is devoted to transitive graphs and trees

Redox proteomics of the inflammatory secretome identifies a common set of redoxins and other glutathionylated proteins released in inflammation, influenza virus infection and oxidative stress

Protein cysteines can form transient disulfides with glutathione (GSH), resulting in the production of glutathionylated proteins, and this process is regarded as a mechanism by which the redox state of the cell can regulate protein function. Most studies on redox regulation of immunity have focused on intracellular proteins. In this study we have used redox proteomics to identify those proteins released in glutathionylated form by macrophages stimulated with lipopolysaccharide (LPS) after pre-loading the cells with biotinylated GSH. Of the several proteins identified in the redox secretome, we have selected a number for validation. Proteomic analysis indicated that LPS stimulated the release of peroxiredoxin (PRDX) 1, PRDX2, vimentin (VIM), profilin1 (PFN1) and thioredoxin 1 (TXN1). For PRDX1 and TXN1, we were able to confirm that the released protein is glutathionylated. PRDX1, PRDX2 and TXN1 were also released by the human pulmonary epithelial cell line, A549, infected with influenza virus. The release of the proteins identified was inhibited by the anti-inflammatory glucocorticoid, dexamethasone (DEX), which also inhibited tumor necrosis factor (TNF)-α release, and by thiol antioxidants (N-butanoyl GSH derivative, GSH-C4, and N-acetylcysteine (NAC), which did not affect TNF-α production. The proteins identified could be useful as biomarkers of oxidative stress associated with inflammation, and further studies will be required to investigate if the extracellular forms of these proteins has immunoregulatory functions

Apolipoprotein B signal peptide polymorphism distribution among South Amerindian populations

This is the published version, also available here: http://www.jstor.org/stable/41465798