Sensitivity to measurement perturbation of single atom dynamics in cavity QED

We consider continuous observation of the nonlinear dynamics of single atom trapped in an optical cavity by a standing wave with intensity modulation. The motion of the atom changes the phase of the field which is then monitored by homodyne detection of the output field. We show that the conditional Hilbert space dynamics of this system, subject to measurement induced perturbations, depends strongly on whether the corresponding classical dynamics is regular or chaotic. If the classical dynamics is chaotic the distribution of conditional Hilbert space vectors corresponding to different observation records tends to be orthogonal. This is a characteristic feature of hypersensitivity to perturbation for quantum chaotic systems.Comment: 11 pages, 6 figure

Mesoangioblasts at 20: from the embryonic aorta to the patient bed

In 2002 we published an article describing a population of vessel-associated progenitors that we termed mesoangioblasts (MABs). During the past decade evidence had accumulated that during muscle development and regeneration things may be more complex than a simple sequence of binary choices (e.g., dorsal vs. ventral somite). LacZ expressing fibroblasts could fuse with unlabelled myoblasts but not among themselves or with other cell types. Bone marrow derived, circulating progenitors were able to participate in muscle regeneration, though in very small percentage. Searching for the embryonic origin of these progenitors, we identified them as originating at least in part from the embryonic aorta and, at later stages, from the microvasculature of skeletal muscle. While continuing to investigate origin and fate of MABs, the fact that they could be expanded in vitro (also from human muscle) and cross the vessel wall, suggested a protocol for the cell therapy of muscular dystrophies. We tested this protocol in mice and dogs before proceeding to the first clinical trial on Duchenne Muscular Dystrophy patients that showed safety but minimal efficacy. In the last years, we have worked to overcome the problem of low engraftment and tried to understand their role as auxiliary myogenic progenitors during development and regeneration

National identity predicts public health support during a global pandemic

Changing collective behaviour and supporting non-pharmaceutical interventions is an important component in mitigating virus transmission during a pandemic. In a large international collaboration (Study 1, N = 49,968 across 67 countries), we investigated self-reported factors associated with public health behaviours (e.g., spatial distancing and stricter hygiene) and endorsed public policy interventions (e.g., closing bars and restaurants) during the early stage of the COVID-19 pandemic (April-May 2020). Respondents who reported identifying more strongly with their nation consistently reported greater engagement in public health behaviours and support for public health policies. Results were similar for representative and non-representative national samples. Study 2 (N = 42 countries) conceptually replicated the central finding using aggregate indices of national identity (obtained using the World Values Survey) and a measure of actual behaviour change during the pandemic (obtained from Google mobility reports). Higher levels of national identification prior to the pandemic predicted lower mobility during the early stage of the pandemic (r = −0.40). We discuss the potential implications of links between national identity, leadership, and public health for managing COVID-19 and future pandemics.publishedVersio

Molecular characterization of adult cardiac stem cells during differentiation towards a pacemaker phenotype

Several cardiac diseases cause disturbances in rhythm propagation, requiring a pharmacological treatment, and/or the implantation of electronic pacemakers. An alternative approach to electronic devices is the \u201cbiological\u201d pacemaker. Possible biological pacemakers consist of cells with pacemaker-like properties, able to pace spontaneously and rhythmically. This work aims to characterize a cellular substrate derived from adult murine stem cells. Self-renewing clones of mesoangioblasts (MABS), obtained from ventricle biopsies, were analyzed for the presence of common stem cell markers. Flow cytometry experiments indicated that these cells are positive for the CD34, c-kit, Sca-1 and CD44 antigens, and for the endothelial antigen CD31. When grown in differentiating medium (low serum, 2%) about 5 days, a fraction of cells started to contract spontaneously. Electrophysiological analysis showed that these cells are able to fire action potentials spontaneously and express the pacemaker current with characteristics similar to the native If (Half-activation at -72.5\ub12.07 mV, n=16). Immunofluorescence was used to investigate the expression of HCN channels, the molecular components of native f-channels. HCN4 was the most expressed isoform; a signal for HCN3 could be detected in a few cells, while the HCN1 and HCN2 isoforms were not detected. As expected, only cells presenting an organized cytoskeleton showed some degree of HCN labeling. Moreover, cells with an organized sarcomeric structure expressed the connexin 43 protein, one of the major components of atrial gap junctions, in vicinity of contacts between cells. In conclusion our data show that MABS could be a potential substrate for the development of a biological pacemaker, although their properties must be further investigated

Adult cardiac stem cells express pacemaker channels following in vitro differentiation

Adult cardiac stem cells express pacemaker channels following in vitro differentiatio

Stromal cell-derived factor-1alpha promotes melanoma cell invasion across basement membranes involving stimulation of membrane-type 1 matrix metalloproteinase and Rho GTPase activities.

Contains fulltext : 58052.pdf (Publisher’s version ) (Closed access)Tissue invasion by tumor cells involves their migration across basement membranes through activation of extracellular matrix degradation and cell motility mechanisms. Chemokines binding to their receptors provide chemotactic cues guiding cells to specific tissues and organs; they therefore could potentially participate in tumor cell dissemination. Melanoma cells express CXCR4, the receptor for the chemokine stromal cell-derived factor-1alpha (SDF-1alpha). Using Matrigel as a model, we show that SDF-1alpha promotes invasion of melanoma cells across basement membranes. Stimulation of membrane-type 1 matrix metalloproteinase (MT1-MMP) activity by SDF-1alpha was necessary for invasion, involving at least up-regulation in the expression of this metalloproteinase, as detected in the highly metastatic BLM melanoma cell line. Moreover, SDF-1alpha triggered the activation of the GTPases RhoA, Rac1, and Cdc42 on BLM cells, and expression of dominant-negative forms of RhoA and Rac1, but not Cdc42, substantially impaired the invasion of transfectants in response to SDF-1alpha, as well as the increase in MT1-MMP expression. Furthermore, CXCR4 expression on melanoma cells was notably augmented by transforming growth factor-beta1, a Matrigel component, whereas anti-transforming growth factor-beta antibodies inhibited increases in CXCR4 expression and melanoma cell invasion toward SDF-1alpha. The identification of SDF-1alpha as a potential stimulatory molecule for MT1-MMP as well as for RhoA and Rac1 activities during melanoma cell invasion, associated with an up-regulation in CXCR4 expression by interaction with basement membrane factors, could contribute to better knowledge of mechanisms stimulating melanoma cell dissemination

Cardiac-derived mesoangioblasts can differentiate into autorhythmic myocytes

Cardiac-derived mesoangioblasts can differentiate into autorhythmic myocyte