1,354,379 research outputs found
Acute mountain sickness in a subject with metabolic syndrome at high altitude
No full textVisitors at high altitude are increasing in age and comorbidities, which can lead
to a failure in acclimatization. We describe the development of acute mountain
sickness (AMS) in a 44-year-old man with metabolic syndrome and the time- and
altitude-dependent correlation between the development of AMS and blood pressure
and heart rate changes. Our observations support a dominant role of endothelial
dysfunction in the pathogenesis of AMS and suggest new behavioral indications
Nuove tecnologie a supporto della ricerca archeologica: applicazioni e sviluppi possibili su sistemi complessi
No full textINTRODUCTION. In the last two decades ground-based geophysical techniques have gained a prominent role in archaeological research projects thanks to ability to localize underground structures or geological body by measuring the variation, or anomalies, of physical properties existing between them and the hosting materials. When applied in archaeology geophysical surveys can reveal the location of buried archeological features and lead to their identification. However, the effectiveness of geophysical techniques applied in archeology is closely linked to the nature and the level of complexity of the buried deposit. If these techniques are used in sites characterized by multi-layered or strongly altered deposits, the survey results may be impaired, severely limiting their contribution to the historical and archaeological reconstruction of the investigated site.
AIM OF THE STUDY. This research project has set two main objectives: i) to evaluate the potential of geophysical prospecting in extracting information in deeply stratified archaeological sites and ii) to test their effectiveness in a contemporary urban setting.
MATHERIAL AND METHODS. The main geophysical technique applied was the Ground Penetrating Radar (GPR). The surveys were carried out using different systems (SIR 3000 GSSI and RIS Hi-Mod IDS) with antennas at different frequencies (from 200 MHz to 900 MHz). GPR data sets have been collected along closely spaced parallel profiles (0.25 to 0.125 m). Data were analyzed using different display methods: radargrams, amplitude depth-slices and three-dimensional models of isosurfaces. GPR data have been merged with historical and archaeological data (vector map of archaeological survey, Digital terrain Models - DTM, historical documents and historical maps) in a Geographic Information System (GIS) with ArcGIS software. ArcGIS is able to import the results of GPR surveys in raster format (amplitude depth-slices) and as three-dimensional models in Multipatch format. Data can be associated with attribute tables and the ArcScene module allows to display them three-dimensionally. Four sites in the historical center of Padua were studied integrating into a GIS the results of GPR surveys with historical and archeological data, two inside religious buildings (the Cathedral and the Church of the Eremitani) and two open areas who insisted on the structures of the ancient palace of the Carraresi. The other case study, focused on the integration of stratigraphic data obtained from archaeological excavations, with those of the geophysical surveys, was carried out in the Roman city of Aquileia (UD).
RESULTS. The integration of the GPR survey of the Cathedral with the available historical maps allowed to recognize the position of a group of tombs that belonged to the previous Romanesque cathedral. It was possible to assume the position of the aisles of transept and of the crypt of the old building. The analysis of the isosurfaces model allowed to hypothesize the presence of a vaulted roof in burials identified below the existing pavement of the Eremitani Church. Moreover, the integration of data about burial distribution in the GIS was consistent with the possible presence in the church of a rood screen demolished in the sixteenth century. In both cases, the two GPR surveys revealed a reduced signal penetration (1-1.2m) and did not allow to identify the remains of walls linked to previous structures. The investigations carried out at the square in front of the Cathedral allowed to relate a series of walls with a complex of buildings dating from XI to XVIII century, when GPR data were compared with historical and archeological data in a GIS. The surveys performed in the palace of the Carraresi showed the presence (and state of preservation) of some portions of the XIV century complex. The same survey identified some previous structures, perhaps dating back to the Roman period. Finally, it was developed a rapid and effective approach for ground-truthing geophysical survey anomalies in the survey done in the Roman city of Aquileia. Moreover, the developed approach could assess the level of resolution of GPR survey by comparing the three-dimensional models of isosurfaces with a DTM from the excavation site obtained with the Structure from Motion technique - SFM
A revision of maximal oxygen consumption and exercise capacity at altitude 70 years after the first climb of Mount Everest
No full textOn the 70th anniversary of the first climb of Mount Everest by Edmund Hillary and Tensing Norgay, we discuss the physiological bases of climbing Everest with or without supplementary oxygen. After summarizing the data of the 1953 expedition and the effects of oxygen administration, we analyse the reasons why Reinhold Messner and Peter Habeler succeeded without supplementary oxygen in 1978. The consequences of this climb for physiology are briefly discussed. An overall analysis of maximal oxygen consumption (VO2max) at altitude follows. In this section, we discuss the reasons for the non-linear fall of VO2max at altitude, we support the statement that it is a mirror image of the oxygen equilibrium curve, and we propose an analogue of Hill's model of the oxygen equilibrium curve to analyse the VO2max fall. In the following section, we discuss the role of the ventilatory and pulmonary resistances to oxygen flow in limiting VO2max, which becomes progressively greater while moving toward higher altitudes. On top of Everest, these resistances provide most of the VO2max limitation, and the oxygen equilibrium curve and the respiratory system provide linear responses. This phenomenon is more accentuated in athletes with elevated VO2max, due to exercise-induced arterial hypoxaemia. The large differences in VO2max that we observe at sea level disappear at altitude. There is no need for a very high VO2max at sea level to climb the highest peaks on Earth. imageAbstract figure legend Maximal oxygen consumption (VO2max) shows a non-linear fall with altitude that is a mirror image of the oxygen equilibrium curve. Di Prampero and Ferretti were the first to associate the non-linear behaviour of the respiratory system to the oxygen equilibrium curve. On the other hand, Wagner constructed his convective curve accounting for the effects of the oxygen equilibrium curve. The decrease is more accentuated in athletic subjects with elevated VO2max compared to those who are non-athletic, so that the large differences in VO2max that are observed at sea level disappear at altitude. Such consequences are due to the effect of ventilatory and pulmonary resistances to oxygen flow in limiting VO2max, which becomes progressively greater while moving toward higher altitudes compared to that of the cardiovascular resistance. On top of Everest, the pulmonary resistances provide most of the VO2max limitation and the respiratory system provides linear responses. imag
A combined computational and experimental approach to human osteocalcin and GPCR Family C Group 6 Member A
No full textINTRODUCTION. The use of mouse genetics recently highlighted coordination by endocrine regulation between bone, energy metabolism, and endogenous sex hormones. Osteocalcin, a bone matrix protein that regulates hydroxyapatite size and shape through its vitamin‑K-dependent γ‑carboxylated form, unraveled endocrinological functions in its circulating forms, that are not only simple markers of bone formation. Undercarboxylated osteocalcin administration regulates gene and protein expression in adipocytes, in pancreatic β cells, and in Leydig cells by a G protein-coupled receptor, GPRC6A receptor, with a potential gender selectivity. Total serum osteocalcin concentrations in humans are inversely associated with measures of glucose metabolism and cardiovascular risk factors; however, human data are inconclusive with regard to the role of uncarboxylated osteocalcin because most studies do not account for the influence of vitamin K or differentiate between the different γ‑carboxylated forms of osteocalcin. Intriguingly GPRC6A receptor mediates also the non-genomic effects of androgens and, although the information about SHBG-receptor structure is not conclusive, evidence seems to suggest that a G protein-coupled receptor is involved.
AIM of the STUDY. Starting from clinical observations, we investigated the protein-protein interaction computational predictors of osteocalcin and SHBG with GPRC6A receptor, and we validated experimentally in vitro in a two-step approach.
MATHERIAL and METHODS. Clinical and biochemical characteristics were studied in a cohort of 91 obese patients and healthy controls in a cross-sectional study. 3-D protein structure alignment analysis and protein docking analysis were resolved with a four (i.e. TM-align, FATCAT, TriangleMatch, TopMatch) and three (i.e. GRAMM-X, ZDOCK, PatchDock) different algorithms approach, respectively. ClickMD-min script was used as a molecular dynamic platform for computational analysis of the conformational structure of osteocalcin in presence or absence of Ca2+, developed with MOE software. Steered molecular dynamics simulations related to the carboxylation state were performed, and the data compared with the spectroscopic techniques results. Gene and protein expression analysis and cell-surface receptor binding assays (i.e. immunofluorescence and flow cytometry analysis) on HEK-293T cells experimentally validated the former results in vitro.
RESULTS. Our study shows for the first time the existence of the competition for a specific binding site between osteocalcin and SHBG on human cells expressing GPRC6A receptor. The results are supported by a computational prediction analysis, describing amino acid residues of SHBG from Gly145 to Leu161 as a highly predicted interface. Our experiments describe the structure of human osteocalcin in its carboxylated and undercarboxylated forms for the first time. The influence of the binding of calcium on osteocalcin structure seems to be stronger than the presence of γ-carboxylated glutamic acid residues. Our clinical data show an imbalance between the γ‑carboxylated forms of osteocalcin in a cohort of hypogonadic obese an overweight patients, with decreased levels of SHBG and altered levels of the other sex hormones.
CONCLUSIONS. The current two-step approach offers a target approach of investigation directly in humans, that has the potential to identify novel pathophysiological pathways as well as novel therapeutic possibilities. The computational basis of the possible binding of SHBG and osteocalcin has been experimentally validated and can directly lead to the synthesis of a peptide, whose physiological and therapeutic implications represent a feasible perspective for future research in an area of paramount importance, such as the cross-talk between bone, energy metabolism, and endogenous sex hormones
Decadimento dei residui di azinphos-methyl e chlorpyriphos-methyl su mele, pesche e nettarine: risultati di una sperimentazione condotta nel Veneto
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EXTENSIVE GEOPHYSICAL INVESTIGATION IN URBAN ENVIRONMENT. THE CASE OF THE EPISCOPAL CENTER OF PADUA
No full textComment on: Acute kidney injury and rhabdomyolysis: a role for the regulator of G-protein signaling (RGS)-2
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