117,476 research outputs found
Association of primary pulmonary hypertension and portal hypertension. Review of the literature and description of 2 further cases]
No full textAbstract
Previous studies have shown that the association between primary pulmonary hypertension and portal hypertension is not merely coincidental. Pathogenesis of this rare combination is unclear, and several hypotheses have been advanced. In the present article, we reviewed the literature on this topic. Two new cases of this syndrome, recently admitted to our hospital, are described. Clinical and laboratory findings of our patients agree with data of the previous case reports
CARDIOVASCULAR REHABILITATION IN PATIENTS WITH DIABETES
No full textPURPOSE:
The cardiovascular disease risk profile and exercise capacity of coronary heart disease patients with type 2 diabetes mellitus (DM) were measured and compared with those of nondiabetic (NDM) patients before and after a 6-week multidisciplinary cardiac rehabilitation program.
METHODS:
Subjects included 413 patients with DM (56.9 +/- 7.9 years) and 614 patients with NDM (56.8 +/- 10.3 years).
RESULTS:
At program entry, DM patients had a higher prevalence of risk factors (hypertension, hypercholesterolemia, hypertriglyceridemia, obesity, excess abdominal fat, and depression), had a lower peak oxygen uptake (14.3 +/- 4.4 vs 16.6 +/- 5.4 mL . kg . min; P < .001), and covered a shorter distance in the 6-minute walk test (404 +/- 117 m vs 445 +/- 116 m; P < .001) than NDM patients. At the end of the exercise program, all patients achieved significant improvements in physical capacity, which were similar in DM and NDM patients (+27.6 +/- 28.2% vs +30.5 +/- 27.7% for peak oxygen uptake and +21.0 +/- 31.5% vs +21.3 +/- 53.2% for the 6-minute distance test).
CONCLUSION:
DM patients with coronary heart disease had a higher prevalence of cardiovascular disease risk factors as well as lower physical capacity than NDM patients at the beginning of rehabilitation. All patients demonstrated improvement in exercise capacity after rehabilitation. More importantly, the extent of the improvement was similar in DM and NDM patients. This study, which involved a large population, emphasizes the capacity of DM patients to fully benefit from a multidisciplinary risk factor management program, including exercise training and educational programs
Self-Assembling l-d-l -Tripeptides Dance the Twist
No full textMinimalistic peptides composed of d - and l -amino acids are attractive building blocks for functional supramolecular materials, including catalysts. d -Amino acids have long been known to promote turn conformations in peptides, yet unexpected twists continue to emerge on their effects on self-assembly. The combination of single-crystal X-ray diffraction and full-atom molecular dynamics have finally unraveled fine details of how l-d-l -tripeptides visit different conformations in solution and establish key interactions in supramolecular structures
Correction to: Influence of cellulose nanofibrils on the rheology, microstructure and strength of alkali activated ground granulated blast-furnace slag: a comparison with ordinary Portland cement (Materials and Structures, (2021), 54, 1, (23), 10.1617/s11527-020-01614-5)
No full textLaura Riva and Carlo Punta have been added to the author group. The change of authorship is due to an error in the recognition of the role and importance of the work of synthesis and characterization of the materials object of the present study, which was not entirely recognized by the inclusion in the acknowledgements. A full recognition of the work performed is obtained by inclusion of the originally omitted authors in the authors’ list. Moreover, a recognition of these authors’ funding body was missing and has been included in the acknowledgement
SELF-ASSEMBLY OF MINIMALISTIC PHENYLALANINE DERIVATIVES INTO SUPRAMOLECULAR HYDROGELS
No full textNel corso degli anni, i materiali nanostrutturati costituiti da piccoli peptidi e con una buona biodegradabilità hanno suscitato un notevole interesse nella ricerca. Grazie ai numerosi vantaggi che presentano rispetto ad altri tipi di materiali (ad es. biocompatibilità, versatilità chimica di composizione e semplicità di preparazione con bassi costi e su grande scala), si è assistito ad un crescente ed attivo interesse verso lo sviluppo di biomateriali di natura peptidica a partire da sequenze il più semplici e brevi possibili, quali singoli amminoacidi o dipeptidi, secondo un approccio di tipo minimalista.
Questa tesi di dottorato, per prima cosa, descrive la capacità di un derivato dell’amminoacido fenilalanina, protetta all’N-terminale in posizione para con un gruppo nitrobenzoile, di auto-assemblarsi in condizioni fisiologiche per formare un idrogel trasparente. Studi preliminari in vitro, hanno rivelato per questo composto una promettente attività antimicrobica ed una buona biocompatibilità verso colture cellulari di mammifero. Successivamente, è stato investigato l’effetto della sostituzione del gruppo N-terminale della fenilalanina con un altro amminoacido di natura idrofobica, quale fenilalanina, leucina, isoleucina o valina, considerando questa sostituzione come una strategia promettente per ottenere biomateriali a partire da dipeptidi capaci di auto-organizzarsi. È stata inoltre esplorata l’influenza della chiralità nei singoli amino acidi, sulla capacità di questi dipeptidi di formare idrogeli. L’eterochiralità si è rivelata una promettente strategia sia per guidare l’organizzazione gerarchica di piccole molecole quali i dipeptidi, specialmente nel caso della difenilalanina, sia per favorirne la loro auto-organizzazione in acqua, aumentando l’idrofobicità della sequenza peptidica. Poichè il fenomeno di auto-organizzazione è un processo cooperativo, anche minime differenze strutturali nella sequenza peptidica, quali la diversa ramificazione della catena alifatica nei tre regioisomeri leucina, isoleucina e norleucina, può essere amplificata e portare a significative differenze a livello sopramolecolare. In questa tesi, infine, è stata investigata anche la possibile influenza dell’alogenazione sull’organizzazione sopramolecolare della difenilalanina eterochirale.
I peptidi sono stati sintetizzati in fase solida, purificati mediante HPLC in fase inversa e caratterizzati a livello molecolare tramite 1H-NMR, 13C-NMR e studi di massa ESI-MS. La capacità di ogni dipeptide sintetizzato di auto-organizzarsi e formare degli idrogeli è stata testata in condizioni fisiologiche (es. soluzioni di tampone fosfato) ed il comportamento sopramolecolare è stato investigato tramite l’utilizzo di diverse tecniche, quali analisi di reologia, dicroismo circolare (CD), spettroscopia infrarossa (FT-IR), saggi di fluorescenza (Th-T) amiloide, microscopia ottica ed a trasmissione elettronica (TEM), diffrazione a raggi X (XRD) su singolo cristallo e su polvere e spettroscopia visibile ed UV-Raman. Infine, la biocompatibilità di questi composti è stata testata in vitro attraverso saggi di citotossicità sia di tipo qualitativo (live/dead) che quantitativo (MTT, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) su culture cellulari di mammifero.
Complessivamente, questa tesi di dottorato consente di definire le regole chiave che guidano l’auto-organizzazione di semplici e piccole molecole, costituite da 1 o 2 amminoacidi, per ottenere biomateriali con ideali caratteristiche di biodegradabilità e biocompatibilità. Inoltre, molti dei sistemi studiati in questa tesi dimostrano la loro capacità di organizzarsi in maniera ordinata a formare interessanti strutture a canale ed idrogel, con promettenti e potenziali applicazioni future nel campo della biomedicina.Biodegradable nanomaterials based on short-peptide building blocks have raised an increasing interest in research over the years. They present several advantages (i.e., biocompatibility, chemical diversity, low cost) relative to other types of materials, and there is a large scope to study minimalistic short sequences as active building blocks for biomaterials, with single amino acids and dipeptides standing out as ideal candidates, athough prediction of their supramolecular behaviour is very challenging.
This PhD thesis aims to fill this gap firstly describing the self-assembly of a N-capped phenylalanine (Phe) derivative into a transparent gel under physiological conditions with promising antimicrobial activity and biocompatibility in vitro. Next, the substitution of the N-cap with another hydrophobic amino acid (i.e., Phe, Leu, Ile, or Val) has been explored as a preferable strategy towards biocompatible self-assembling dipeptides, and effects of amino acid chirality over gelation has been studied. Heterochirality revealed to be a successful strategy to control the hierarchical assembly of dipeptides, especially in the case of Phe-Phe, and to promote self-assembly in water through increased peptide hydrophobicity. As self-assembly is a cooperative process, small structural sequence differences (i.e., branching of the aliphatic amino acid sidechain for the regioisomers Leu and Ile) can be amplified and lead to significant supramolecular differences. Furthermore, halogenation was studied for its influence on the supramolecular organization of D-Phe-L-Phe.
Peptides were synthesized by Fmoc-based solid-phase peptide synthesis, purified by reverse-phase HPLC and characterized by 1H-NMR, 13C-NMR and ESI-MS. Self-assembly was probed under physiological conditions (i.e., phosphate buffered solutions) and the supramolecular behaviour was investigated by means of rheology, circular dichroism (CD), Fourier-transformed infrared spectroscopy (FT-IR), Thioflavin T fluorescence, optical imaging, transmission electron microscopy (TEM), powder and single-crystal X-ray diffraction (XRD), visible and UV-resonant Raman spectroscopy. Finally, biocompatibility was assayed qualitatively (live/dead) and quantitatively (MTT, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide).
Overall, this PhD thesis allows to delineate design rules for the self-assembly of very simple building blocks based on 1-2 amino acids into biocompatible biomaterials and outlines several examples of supramolecular water-channels and hydrogels with potential applications in medicine
Multisensor Online Transfer Learning for 3D LiDAR-Based Human Detection with a Mobile Robot
No full textHuman detection and tracking is an essential task for service robots, where the combined use of multiple sensors has potential advantages that are yet to be fully exploited. In this paper, we introduce a framework allowing a robot to learn a new 3D LiDAR-based human classifier from other sensors over time, taking advantage of a multisensor tracking system. The main innovation is the use of different detectors for existing sensors (i.e. RGB-D camera, 2D LiDAR) to train, online, a new 3D LiDAR-based human classifier based on a new "trajectory probability". Our framework uses this probability to check whether new detection belongs to a human trajectory, estimated by different sensors and/or detectors, and to learn a human classifier in a semi-supervised fashion. The framework has been implemented and tested on a real-world dataset collected by a mobile robot. We present experiments illustrating that our system is able to effectively learn from different sensors and from the environment, and that the performance of the 3D LiDAR-based human classification improves with the number of sensors/detectors used
Compositional characterization of Etruscan earthen architecture and ceramic production
No full textThis study presents the results of new research into Etruscan technology for earthen architecture as well as ceramic production in the upper Tiber Valley in central Italy, using as a case study the Etruscan settlement of Col di Marzo (Perugia). It determines the compositional differences of the raw material employed as building material and for ceramic production by X-ray powder diffraction (XRD), thermogravimetric analysis and differential thermal analysis (TG-DTG), Fourier-transform infrared analysis (FTIR) and geotechnical analyses. The research also advances the knowledge of ceramic manufacturing technology, with a focus on impasto production, at Col di Marzo between the fifth and mid-third centuries bce and the surrounding territory on the left bank of the River Tiber. The compositional analysis of building material compared with the ceramics provides answers to questions related to their sourcing and deepens the understanding of the exploitation of natural resources
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