89,081 research outputs found
Analysis of chromosome aberrations in somatic and germ cells of the mouse
No full textChromosome aberration tests are used to evaluate the clastogenicity of chemical and physical agents, that is, the capacity of these agents to cause breaks in chromosomes and produce microscopically visible fragments or structural rearrangements. Aberrations are scored in metaphase chromosomes of dividing cells. In the mouse, bone marrow progenitors of erythrocytes and leukocytes provide abundant metaphases to study the effects on somatic cells, whereas the response of male germ cells to clastogenic agents can be visualized on metaphases of spermatogonia and primary spermatocytes. The techniques to prepare the slides for analyses are well standardized and internationally harmonized protocols for tests in bone marrow and spermatogonia provide the guidance necessary to obtain meaningful results. It is advisable to adhere as much as possible to these recommendations. Not all tests are suitable to score the same kind of aberrations. Here an overview of the application domains of these tests is provided with warnings on the scoring criteria and statistical analysis. © Springer Science+Business Media, New York 2013
Pig red blood cell hexokinase: evidence for the presence of hexokinase types II and III, and their purification and characterization
No full text: Pig erythrocytes, in contrast to red blood cells from other mammals (M. Magnani, V. Stocchi, F. Canestrari, M. Dachà, and G. Fornaini (1982) Biochem. Int. 4, 673), have been shown to contain hexokinase (EC 2.7.1.1) types II and III. Hexokinase type III is the predominant form, accounts for 98% of the total glucose phosphorylating activity, and has been purified 290,000-fold by a combination of ion-exchange chromatography and affinity chromatography on Sepharose-N-hexanoylglucosamine. The enzyme was shown to be homogeneous by polyacrylamide and sodium dodecyl sulfate-gel electrophoresis. The highest specific activity obtained was 190 units/mg protein with a yield of 60%. Because the amount of hexokinase II was small, it was only partially purified by ion-exchange chromatography. The native proteins have the same molecular weight of 100,000 by gel filtration on Ultrogel AcA44. The apparent isoelectric point of hexokinase type II was shown to be 4.8 and 4.9 pH units, whereas hexokinase type III was shown to have a pI of 4.3 to 4.4 pH units by isoelectric focusing. Both hexokinases are able to phosphorylate several hexoses. However, while hexokinase II shows an apparent Km for glucose of 1.5 X 10(-4) M with negative cooperativity (nH = 0.4), hexokinase III shows an apparent Km for glucose of 1.5 X 10(-5) M and a positive cooperative effect (nH = 1.5). Furthermore, glucose at concentrations higher than 0.4 mM becomes an inhibitor of hexokinase III. Amino acid analysis of hexokinase type III revealed a low number of the aromatic residues Phe, Tyr, and Trp; this is in agreement with the low extinction coefficient of E1(0nm = 12.5
Glacio-isostatic adjustment in the Po plain and in the northern Adriatic region
No full textVertical movements in the Po plain (northern Italy) are controlled by natural and anthropogenic
effects. Since Italy is located in the far–field of the former late Pleistocene ice sheets, isostatic deformations are
primarily driven by melt water loading and represent a major component of long–term natural movements across
the entire Mediterranean. In addition to far–field sources, here we consider the isostatic effects of melting of the
nearby Wu ̈rm Alpine ice–sheet, suggesting that it is possible to put bounds on its maximum thickness, extent
and chronology by Holocene relative sea level observations from the northern Adriatic. Using various plausible
ice models, and adopting a viscosity profile that matches Holocene relative sea level observations in the
Mediterranean, we find that melting of the Alpine ice sheet is always responsible for upward movements in the
Po plain, currently at rates of * 0.5 mm/yr. When both far– and near–field sources are considered, the rate of
sea level change in the Venetian Lagoon for the most reasonable mantle rheology and melting chronology is
negative, i.e., opposite to that attributed to human activity and recent climatic variations. However, its amplitude
(fractions of mm/yr) is small compared to the secular signal observed by tide gauges (*2 mm/yr), which makes
glacial isostasy a second–order mechanism of sea level variation in this region
Determination of the CKM unitarity triangle parameters by end 1999
No full textTalk given by A. Stocchi at the Third International Conference on B physics and CP violation, National Taiwan Univ., Taipei, Tawain, December 3-7, 1999Within the Standard Model, a review of the current determination of the CKM unitarity triangle parameters is presented, using experimental constraints from the measurements of |epsilon_K|, V_ub/V_cb, Delta m_d and from the limit on Delta m_s, available by end 1999
Validation of the PARC_CL 2.0 crack model for the assessment of the nonlinear behaviour of RC structures subjected to seismic action: SMART 2013 shaking table test simulation
No full textPresented in the paper is the new PARC_CL 2.0 crack model, a physical approach for RC modelling especially tailored to shear sensitive structures. The model is then applied for the seismic response assessment of the SMART 2013 specimen, a scaled RC nuclear power plants facility wall structure tested on a shaking table under strong seismic input. The aim of the research is to evaluate the predictive capacity of the modelling in terms of global and local response, in order to try to partially fill the gap for the need of non linear calculation for large structures and applicability of the modelling technique to the practice. The presented approach demonstrated to be able to provide satisfying results in terms of top displacement, floor acceleration spectra, interstorey drift and eigen frequency drop off. Moreover, the modelling using shell elements demonstrated to keep the amount of computational cost acceptabl
Bounds on the time-history and Holocene mass budget of Antarctica from sea-level records in SE Tunisia
No full textSolving the sea–level equation for a Maxwell Earth, we analyze the sensitivity of Holocene sea–level records in SE Tunisia to the time–history of remote ice sheets. Assuming that mantle viscosity increases moderately with depth, we find that in this region the sea–level variations driven by the Northern Hemisphere ice sheets cancel, so that the late–Holocene sea–level high–stand suggested by the geological record merely reflects the melting history of Antarctica. New insight into the history of this ice sheet is obtained analyzing the information contained in a revised set of relative sea–level observations for sites across the Mediterranean covering the last 8 kyrs. From a trial–and–error misfit analysis, it holds true that in this region the match between model predictions and observations improves when the volume of water released from Antarctica is well below the value imposed by the ICE3G chronology and when a sudden meltwater pulse is allowed between 8 and 7 kyrs before present, corresponding to the epoch of the catastrophic rise event known as CRE3
The timescale and spatial extent of vertical tectonic motions in Italy: insights from relative sea-level changes studies
No full textVertical tectonic displacements in Italy since 125 to 1 Kyr BP are drawn from relative sea-level (RSL)
history studies at coastal sites, and, together with instrumental observations, allow to bridge the gap with events
recorded in the geologic (1 Ma) archive. Our analysis aims at establishing the appropriate spatial extent, rate and
duration of vertical tectonic motion within individual crustal segments, and at placing constraints on the contribution
to displacements coming from regional (deep) and local (shallow-crustal) sources. The central and northern
Tyrrhenian Sea and the Ligurian Sea margins show stability at all scales, except for subsidence in coastal basins and
uplift, at places high, at volcanic centers. On the contrary, sustained, large magnitude uplift of Calabria embeds a
deep-seated contribution, highlighted by the spatial coincidence of the uplifting province with a lithospheric slab, and
a contribution from local faults and folds. Holocene uplift was up larger than since Middle-Late Pleistocene, with rate
changes tuned among all sites. The recent increase in uplift rate, detected also in the instrumental record, is related to
clustering of strain release, possibly triggered by isostatic response to deglaciation. A weak deformation signal is
recorded on the central Adriatic coastline, and records slow Apennines thrust belt migration. In the northern Adriatic
Sea, vertical tectonic motions result from opposite displacements in the southern Alps, internal Dinarids and northern
Apennines, but flexure of the Adriatic (micro-) plate beneath the Northern Apennines is the dominating contributor.
Here, rate and spatial extent of displacements are steady over different time-scales, suggesting prevailing control
exercised by plate dynamics
Validation of the PARC_CL 2.0 Crack Model by the Cyclic Tests of 1/13 Scale Nuclear Containment Structures
No full textPhysical activity and neurotrophic factors as potential drivers of neuroplasticity in Parkinson's Disease: A systematic review and meta-analysis
No full textParkinson's disease (PD) is a neurodegenerative disorder, characterized by motor and non-motor symptoms, that still lacks of a disease-modifying treatment. Consistent evidence proved the benefits of physical therapy on motor and non-motor symptoms in PD patients, leading the scientific community to propose physical activity as disease-modifying therapy for PD and suggesting the involvement of neurotrophic factors (NFs) as key mediators of neuroplasticity. However, the lack of standardized exercise training and methodological flaws of clinical trials have limited the evidence demonstrating the exercise-induced changes in serum and plasma neurotrophic factors concentration. A systematic search, covering 20 years of research in this field and including randomized and non-randomized controlled trials (RCTs and non-RCTs), which reported changes in serum and plasma NFs after a specific intervention, were reviewed. Pooled effect sizes (p-ESs) and 95% confidence intervals (95%CIs) were calculated using a random effects model with R software. A total of 18 articles, of which exercise programs of interventions were codified in terms of type, intensity and duration adopting a standardisation methodology, were included in the systematic review. Six papers, describing the effect of different training programs on BDNF and IGF-1 levels, were included and independently analysed in two meta-analyses. Quantitative analysis for BDNF indicated a statistically significant improvement in serum concentration of PD patients (MD: 5.99 ng/mL; 95%IC: 0.15-11.83; I2 = 77%) performing physical activity compared with control conditions in RCTs. Pre-liminary evidence supported the hypothesis that a moderate intensity aerobic exercise (MIAE) would be necessary to induce the changes in NFs. However, sensitivity analysis of meta-analysis and the few studies included in subgroup analysis did not support these results. Alongside, meta-analysis followed by sensitivity analysis revealed a potential change in serum IGF-1 (MD: 33.47 ng/mL; 95%IC: 8.09-58.85) in PD patients performing physical activity with respect controls in RCT studies. Considering the limited evidence to support or refute the increase in NFs levels in PD patients performing physical activity, there is a need to develop a rigorous controlled randomized trial, with standardization for loading intensity of physical activity, greater sample size, and a correct stratification of PD patients to establish a well-defined correlation between physical activity and NFs levels
Transient left bundle branch block following intravenous lisuride bolus
No full text[No abstract available
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