Italian Map of Design Earthquakes from Multimodal Disaggregation Distributions: Preliminary Results.

Probabilistic seismic hazard analysis allows to calculate the mean annual rate of exceedance of ground motion intensity measures given the seismic sources the site of interest is subjected to. This piece of information may be used to define the design seismic action on structures. Moreover, through disaggregation of seismic hazard, it is possible to identify the earthquake giving the largest contribution to the hazard related to a specific IM value. Such an information may also be of useful to engineers in better defining the seismic treat for the structure of interest (e.g., in record selection for nonlinear seismic structural analysis). On the other hand, disaggregation results change with the spectral ordinate and return period, and more than a single event may dominate the hazard, especially if multiple sources affect the hazard at the site. In this work disaggregation for structural periods equal to 0 sec and 1.0 sec is presented for Italy, with reference to the hazard with a 475 year return period. It will be discussed how for the most of Italian sites more than a design earthquake exist, because of the modelling of seismic sources

Keratan sulphate in the tumour environment

Keratan sulphate (KS) is a bioactive glycosaminoglycan (GAG) of some complexity composed of the repeat disaccharide D-galactose β1→4 glycosidically linked to N-acetyl glucosamine. During the biosynthesis of KS, a family of glycosyltransferase and sulphotransferase enzymes act sequentially and in a coordinated fashion to add D-galactose (D-Gal) then N-acetyl glucosamine (GlcNAc) to a GlcNAc acceptor residue at the reducing terminus of a nascent KS chain to effect chain elongation. D-Gal and GlcNAc can both undergo sulphation at C6 but this occurs more frequently on GlcNAc than D-Gal. Sulphation along the developing KS chain is not uniform and contains regions of variable length where no sulphation occurs, regions which are monosulphated mainly on GlcNAc and further regions of high sulphation where both of the repeat disaccharides are sulphated. Each of these respective regions in the KS chain can be of variable length leading to KS complexity in terms of chain length and charge localization along the KS chain. Like other GAGs, it is these variably sulphated regions in KS which define its interactive properties with ligands such as growth factors, morphogens and cytokines and which determine the functional properties of tissues containing KS. Further adding to KS complexity is the identification of three different linkage structures in KS to asparagine (N-linked) or to threonine or serine residues (O-linked) in proteoglycan core proteins which has allowed the categorization of KS into three types, namely KS-I (corneal KS, N-linked), KS-II (skeletal KS, O-linked) or KS-III (brain KS, O-linked). KS-I to -III are also subject to variable addition of L-fucose and sialic acid groups. Furthermore, the GlcNAc residues of some members of the mucin-like glycoprotein family can also act as acceptor molecules for the addition of D-Gal and GlcNAc residues which can also be sulphated leading to small low sulphation glycoforms of KS. These differ from the more heavily sulphated KS chains found on proteoglycans. Like other GAGs, KS has evolved molecular recognition and information transfer properties over hundreds of millions of years of vertebrate and invertebrate evolution which equips them with cell mediatory properties in normal cellular processes and in aberrant pathological situations such as in tumourogenesis. Two KS-proteoglycans in particular, podocalyxin and lumican, are cell membrane, intracellular or stromal tissue–associated components with roles in the promotion or regulation of tumour development, mucin-like KS glycoproteins may also contribute to tumourogenesis. A greater understanding of the biology of KS may allow better methodology to be developed to more effectively combat tumourogenic processes

Cell-extrinsic requirement for sulfate in regulating hippocampal neurogenesis

Sulfate is a key anion that is required for a range of physiological functions within the brain. These include sulfonation of extracellular proteoglycans to facilitate local growth factor binding and to regulate the shape of morphogen gradients during development. We have previously shown that mice lacking one allele of the sulfate transporter exhibit reduced sulfate transport into the brain, deficits in social behaviour, reduced performance in learning and memory tasks, and abnormal neurogenesis within the ventricular/subventricular zone lining the lateral ventricles. However, whether these mice have deficits in hippocampal neurogenesis was not addressed. Here, we demonstrate that adult mice have increased neurogenesis within the subgranular zone (SGZ) of the hippocampal dentate gyrus, with elevated numbers of neural progenitor cells and intermediate progenitors. In contrast, by 12 months of age there were reduced numbers of neural stem cells in the SGZ of heterozygous mice. Importantly, we did not observe any changes in proliferation when we isolated and cultured progenitors in neurosphere assays, suggestive of a cell-extrinsic requirement for sulfate in regulating hippocampal neurogenesis. Collectively, these data demonstrate a requirement for sulfate transport during postnatal brain development to ensure normal adult hippocampal neurogenesis

Opposing effects of α2- and β-adrenergic receptor stimulation on quiescent neural precursor cell activity and adult hippocampal neurogenesis

Norepinephrine regulates latent neural stem cell activity and adult hippocampal neurogenesis, and has an important role in modulating hippocampal functions such as learning, memory and mood. Adult hippocampal neurogenesis is a multi-stage process, spanning from the activation and proliferation of hippocampal stem cells, to their differentiation into neurons. However, the stage-specific effects of noradrenergic receptors in regulating adult hippocampal neurogenesis remain poorly understood. In this study, we used transgenic Nestin-GFP mice and neurosphere assays to show that modulation of α2- and β-adrenergic receptor activity directly affects Nestin-GFP/GFAP-positive precursor cell population albeit in an opposing fashion. While selective stimulation of α2-adrenergic receptors decreases precursor cell activation, proliferation and immature neuron number, stimulation of β-adrenergic receptors activates the quiescent precursor pool and enhances their proliferation in the adult hippocampus. Furthermore, our data indicate no major role for α1-adrenergic receptors, as we did not observe any change in either the activation and proliferation of hippocampal precursors following selective stimulation or blockade of α1-adrenergic receptors. Taken together, our data suggest that under physiological as well as under conditions that lead to enhanced norepinephrine release, the balance between α2- and β-adrenergic receptor activity regulates precursor cell activity and hippocampal neurogenesis

Stimulation of α2-adrenergic and β-adrenergic receptors exerts opposing effects on proliferative activity of Nestin-positive hippocampal precursor cells.

<p>(A) Nestin-positive cells from the adult hippocampus were sorted using flow cytometry based on their GFP expression. (B) Treatment with the α2-adrenergic receptor agonist guanabenz directly and significantly inhibited Nestin-GFP-positive hippocampal precursor cell proliferation as measured by a significant decline in neurosphere number. In contrast, treatment with the β-adrenergic receptor agonist isoproterenol significantly increased Nestin-GFP-positive hippocampal precursor cell proliferation with an enhanced number of neurospheres noted following isoproterenol treatment. The increased neurosphere numbers induced by isoproterenol were comparable to the induction observed following norepinephrine treatment. (mean±SEM, *<i>p</i><0.05, n = 3 experiments).</p

Summary of the stage-specific effects of sub-class selective adrenergic receptor agonists and antagonists on hippocampal precursor activity and neurogenesis.

<p>NC: No change;</p><p>→: Increased;</p><p>←: Decreased;</p><p>→^*: <i>p</i> = 0.06.</p

Stimulation of β-adrenergic receptors enhances hippocampal precursor activity whereas blockade inhibits precursor activity and decreases neurogenesis.

<p>(A) Treatment of primary hippocampal cells with β-adrenergic receptor agonist isoproterenol at 1 and 10 µM significantly increased where as with antagonist propranolol (0.1 and 10 µM) decreased neurosphere formation (n = 4 experiments). (B) Neurospheres obtained in the presence of isoproterenol were similar to norepinephrine-derived neurosphere, particularly the emergence of a small proportion of very large neurospheres measuring >200 µm in diameter. (C) A significantly large proportion of isoproterenol-treated neurospheres contained both neurons and astrocytes similar to that observed in norepinephrine-derived neurospheres. Proportion of neurospheres expressing neuronal marker βIII tubulin was significantly reduced in propranolol-treated neurospheres compared to control. (D, E) Representative photomicrographs of BrdU- and DCX-labeled cells from control, isoproterenol and propranolol-treated mice. (F) <i>In vivo</i> administration of isoproterenol increased whereas propranolol decreased the number of BrdU-positive cells in the SGZ (n = 4–5 mice per group). (G) While a trend towards an increase in Nestin-GFP-positive cells was obtained following isoproterenol treatment, propranolol treatment did not alter GFP-positive cell numbers in SGZ. (H) The percentage of Nestin-GFP/GFAP double-positive cells was significantly enhanced by isoproterenol treatment where as propranolol treatment (I) led to a significant reduction in double-positive cells compared to the vehicle-treated control group. (J) Propranolol treatment resulted in a significant reduction in DCX-positive immature neuron pool. (mean±SEM, *<i>p</i><0.05, **<i>p</i><0.01, ***<i>p</i><0.01).</p

Summary of the stage-specific effects of sub-class selective adrenergic receptor agonists and antagonists on hippocampal precursor activity and neurogenesis.

<p>NC: No change;</p><p>→: Increased;</p><p>←: Decreased;</p><p>→^*: <i>p</i> = 0.06.</p

Dose and concentrations of sub-class-selective adrenergic receptor agonists and antagonists used in this study.

<p>Dose and concentrations of sub-class-selective adrenergic receptor agonists and antagonists used in this study.</p