702 research outputs found
Sort by
I sarcomi uterini: casistica osservata, protocolli attuati e prospettive terapeutiche.
No full textmissin
Muscle development and differentiation in the urodele Ambystoma mexicanum.
No full textSkeletal muscle in vertebrates is the most representative tissue and it is composed by different types of fibers which differ for anatomical and physiological features. These traits permit to distinguish them basing on the speed of twitch and the load resistance. The characteristics of a fiber depend on the amount of glycogen and mitochondria in their cytoplasm, as well as by the presence of glycolitic and oxidative enzymes.
In particular, slow fibers are specific for a long-lasting contraction, they express a MyHC isoform having an ATPase activity at acidic pH (pH 4.0) and an aerobic oxidative metabolism. In contrast, fast fibers are larger in size, with few mitochondria. They are specialized in rapid and short-lasting contractions and express a MyHC isoform, having an ATPase activity at basic pH (pH 10.0) and an anaerobic glycolitic metabolism.
These different types of fibers, both in amniotes and in lower vertebrates such as fish and anuran amphibians s come from distinct populations of myoblasts which appear in the somites during the embryonic development.
Even if substantial data concerning the muscle differentiation and the characterization of the different types of fibers in zebrafish and Xenopus are available, nothing is still known about the mechanisms regulating these processes in amphibian urodeles. Since these animals present some anatomical features and life style between fish and anurans, the study of myogenic processes in these animals could be useful to clarify the evolutionary changes which lead to the formation of skeletal muscle in the trunk of land vertebrates.
To shed light on the myogenic processes in urodele amphibians we focused our studies on the axolotl Ambystoma mexicanum and we analysed several embryonic stages of this amphibian in order to identify the different types of fibers and their pattern of distribution during the myogenic process. Using morphological analysis, enzymatic hystochemistry and immunohystochemistry we showed that in A. mexicanum, as in zebrafish, the first differentiating fibers are the slow ones deriving from myoblasts localized close to the notochord.
These fibers then migrate towards the somitic surface and here they give rise to a uperficial layer of slow fibers, while the myoblasts forming the medial part of the somite differentiate into fast fibers.
Further, in order to evaluate the possible involvement of muscle-specific transcriptional factors and protein signalling in the regulation of myogenic process of this amphibian, we used molecular biological approaches to identify and clone the muscle-specific transcriptional factor (Myf5) and the Sonic hedgehog signalling protein, known to regulate the muscle development and differentiation both in amniotes and lower vertebrates
Psicofarmaci e polifarmacoterapia come fattori di rischio per le cadute negli anziani istituzionalizzati: uno studio trasversale in una residenza socio assistenziale lombarda.
No full textmissin
Semantics foundations for constructive description logics.
No full textIn this work we present our contributions to the study of semantics foundations for constructive description logics. In particular, we propose a Kripke style semantics for the basic description logic ALC, and we give a sound and complete tableau calculus for this semantics.
Then we exploit an information term semantics for description logics to formalize an action language for ALC. Finally, we define a semantics for ALC which is directly inspired by the Kripke style semantics for intuitionistic modal logics and we give a sound and complete tableau calculus for this semantics
Terremoti crostali e zonazione sismica dell’Ecuador attraverso l’integrazione dei dati geologici, sismologici e morfostrutturali.
No full textmissin
Coastal fish assemblages associated with rocky substrates: differences between a marine reserve (Pianosa island) and an unprotected area (Elba island).
No full textAlong the coastline of Italy, there are many areas of high environmental value.
Nevertheless, only for few of these the protection proposed in 1982 by low has been really enforced. Understanding if marine reserves work, requires two levels of analysis.
The first requires that particular reserves be evaluated in the context of the goals inherent in their establishment. The second level of analysis should be a broad comparison across reserves in different ecosystems to understand if reserves in general have a local or regional effect. Fish assemblage inside the MPAs, usually include many species targeted by fishing, so that they are primarily expected to benefit from protection, especially those having no-take reserve. The evaluation of the benefits, in terms of increase in density and size of target fishes can be useful to assess the ecological effectiveness of reserves. Up to now, there are very few long-term series of density estimates in and around MPAs before and after protection to verify these assumptions in the context of protected populations.
Fish fauna distributions patterns can be useful for testing the effectiveness of habitat protection in marine reserves. Most target fishes are high-levels predator and their functional extinction may cause community wide changes. The impact of fishing has consequent top-down perturbations in marine communities structures and organization.
Benthic communities in the shallow Mediterranean rocky sublittoral have 2 extreme alternative succession endpoints: coralline barrens and complex macroalgal beds. In the Mediterranean, Paracentrotus lividus is a key species that a high densities influences the dynamics of the phytobenthos, by eliminating erect algae and seagrasses, and inducing the formations of coralline barrens. Despite ecologists’ increasing interest in fish fauna living in marine protected areas, fish assemblage of some Italian marine reserves are still completely unknown.
Pianosa represents the ideal area where to verify the hypothesis that are the subject of this PhD. The PhD thesis is aimed at: 1- determine the structure of the infalittoral fish assemblage inhabiting the protected (Pianosa Island) and adjacent (Elba Island) non protected areas of Tuscan Archipelago, in terms of species composition, diversity and relative density, assessing differences in the community parameters in different areas; 2- to estimate the fish community responses to the trophic cascades in shallow rocky shores as possible results that indicate the reserve effect.
In infralittoral area, is possible to assess that structure of rocky fish assemblage testing the effectiveness of habitat protection in MPAs? Underwater Visual Census (UVC) is choised as the more appropriate method to conduct study on infralittoral fish community in Pianosa and Elba islands. Abundance data were collected by using a scale based on a geometric progression factor which was approximately 2. Fish density was calculated by considering the mid point of each abundant class. The size of individual fish was assigned to one of four size classes.
Extensions of barren cover, was visually estimated as relative percentage by means of square of 1 m-2 located on the bottom. P. lividus was chosen as indicator liable to possible shift from macroalgal cover to barren.
During the survey the degree of exploitation on fish species at Elba island, was evaluated on the basis of direct observation of fishing landings in Marina di Campo harbour.
A one way ANOVA was performed to test for differences among the areas in the assemblage parameters. Permanova was performed to test differences in analysis fish community using locality as fixed factor. The reserve effect (response ratio, R), was calculated for trophic categories and exploitation levels, as ln of ratio between value of response variable (density) inside the protected area and in fished areas.
During this study, 46 fish species were identified. Labridae and Sparidae were the most relevant families in relation to species richness. Some large sized specimens, belonging to species of high commercial value (i.e. Seriola dumerilili, Dentex dentex, and Ephinephelus marginatus), were also observed.
Taxonomic composition of fish community in Pianosa and Elba islands agrees with other similar northern-western in Mediterranean. The abundance of target species correlates strongly with the reserve effect, and therefore shows that the reserve has been effective in providing protection for such species. Some highly spearfished species such as E. marginatus, S. umbra, or D. dentex, have been censed exclusively within the reserve. Other such as Sparus aurata are far more abundant in the reserve. Species diversity index, and Evenness, show significant differences between sites located in Pianosa. Here, Diplodus vulgaris and Diplodus sargus, showed higher abundance in protected than in unprotected area. The study of four size classes of some target species has confirmed that large individuals were significantly more abundant in the protected area.
The increase of the size of fishes is a phenomenon widely reported in other MPAs and this general pattern has primarily attributed to the lack of fishing impact. Protected area seems to have the potential to restore depleted fish stocks. The response ratio evaluated for exploitation level shows that the reserve has been effective in protection for heavily fished species. Protected area, support greater density of D. sargus and D. vulgaris as predators on sea urchin P. lividus, than unprotected area. At the same time, the cover of barrens was significantly higher in unprotected area than in Pianosa. This study has evidenced a reserve effect or refuge effect characterized by the presence of large individuals. This refuge effect, within the presence of large individuals and species vulnerable to fishing, is one of the characteristics described in the definition of reserve effect. The results of the present study suggest that the recovery of Diplodus species in Pianosa seems to reestablish predatory control upon P. lividus similar to what is observed in other temperate regions and in other Mediterranean protected areas. The results of this study can corroborate the hypothesis of a transition from macroalgal beds, which harbour hundred of species of algae and invertebrates, to barrens through sea urchins grazing.In protected area, the effect of predator density on prey and on its population parameter is density-mediated indirect interactions (DMIIs).
This study, is a further step toward a better knowledge of the rocky reef fish assemblage of this area. At the community level, the present study will provide a useful reference point for planning future investigations on inter-specific relationship such as competition. Pianosa is an protected area where is possible to demonstrate that reserves aimed at restoring whole assemblages and ecological processes should be established as permanent no take area. This studies confirms that besides direct effects on target species, fishing may cause changes in trophic relations and in ecosystem functioning. Despite Pianosa is not a typical MPA since actual permanent presence of penal institute, it represent an important site where to study isolated infralittoral fish community on rocky substrata. It is clear that future experiments testing the reserve effect on fish biodiversity will have to take into account the necessity of being repeated on larger spatial and temporal scales
Allostery in a monomeric protein: the case of human serum albumin.
No full textHuman serum albumin (HSA), the most prominent protein in plasma, binds different classes of ligands at multiple sites. HSA provides a depot for many compounds, affects pharmacokinetics of many drugs, holds some ligands in a strained orientation providing their metabolic modification, renders potential toxins harmless transporting them to disposal sites. Its modular domain organization provides a variety of ligand-binding sites and the flexible modular structure involves more than the immediate vicinity of the binding site(s), affecting the ligand-binding properties of the full protein. Ferric human serum heme–albumin (heme– HSA) shows a peculiar spectroscopic properties that allow to investigate structural and functional aspects of the protein.
Here, a characterization of the environment of the metal binding site and of its dynamics is reported. Moreover, the effect of different endogenous and exogenous ligands on the allosteric properties of HSA and link between binding sites are investigated.
As a whole, the complex mechanism modulating ligand binding to HAS represents one of the most important structure-function correlations ever reported for monomeric proteins in general
Validazione del protocollo analitico di equilibrazione competitiva dei leganti accoppiata a stripping catodico per la speciazione di elementi in traccia.
No full textThe analytical performances of Competitive Ligand Equilibration with Cathodic Stripping Voltammetric detection of the labile fraction (CLE-CSV) were assessed and optimized. This speciation method enables the concentration of natural ligand(s) and their conditional stability constants for the complexation of the investigated metal to be determined through thermodynamic considerations.
The CLE-CSV procedure requires three working steps: firstly, total metal determination has to be performed with a good accuracy and precision; secondly, the calibration of the alfa coefficient of the added ligand with the metal considered is required; finally, titration of the samples with increasing metal additions provides the speciation results mentioned above.
To allow an accurate and precise measurement of the total metal concentration at trace levels (nM), the entire analytical procedure was assessed in term of effect of acidification of the samples and/or reagents required for the analysis and in term of influence of the UV-photooxidation used as pretreatment step for the total metal quantification with voltammetric techniques. The purity grade of nitric and hydrochloric acids produced by subboiling distillation was evaluated with the aim to avoid metal contamination during acidification processes. UV-photooxidation is commonly accepted as a sample pretreatment for voltammetric measurements to remove organic matter. Starting from the critical evaluation of the performances and costs of the commercially available systems, we decided to design and develop a prototype UV-digester, using only commonly commercialised parts (e.g. low cost, standard connection UV lamps). As a result, the target of coupling low investment and low maintenance costs to high performances is completely fulfilled. Its suitability for the treatment of natural waters prior to cathodic stripping voltammetry was assessed: the total concentration of copper, uranium and platinum in natural waters could be reliably determined applying a 30 minute UV treatment.
The final aim of this doctorate thesis is the complete evaluation of the speciation procedure CLE-CSV in term of accuracy and precision