131,834 research outputs found
Behind beta cell glucotoxicity: a pivotal role of glycoxidative damage?
No full textThis book presents current research from across the globe in the study of Beta-cells, including the induction of pancreatic cancer cell death by elevated concentrations of extracellular zinc; the role of Rab GTPases and their effectors in the insulin secretory pathway of the pancreatic beta cell; In vivo reprogramming of pancreatic A-cells into B-like cells; and the role of glucocortoids, exercise and glucolipotoxicity with regard to stress and pancreatic B-cell function.Type 2 diabetes, which is the most common form of diabetes, is characterized by hyperglycemia and insulin resistance associated with a progressive deterioration of β-cell function and mass. High blood glucose plays a key role in the development of diabetic complications and may contribute to the progressive β-cell failure. Chronic exposure to high glucose levels increases non enzymatic reactions between aldehydic and amino group of molecules like sugars and proteins, lipids or nucleic acids leading to Advanced Glycation End-Products (AGEs) formation. Accumulation of AGEs is related to the aging process and is boosted by diabetes. Although the pathogenic role of AGEs in microvascular complications of diabetes has been widely investigated and recognized, their role in pancreatic β-cell dysfunction remains to be fully elucidated. Evidence of a direct role of AGEs on pancreatic β-cell dysfunction is discussed in this review. Findings show that exposure to high AGE concentration damages the β-cell functionality affecting insulin production and disturbing the insulin secretion machinery. The studies provide solid evidence that AGEs not only may play a causative role in diabetes complications but may be crucial in the onset and maintenance of it
Erosione ed uso del suolo: indicazioni per la gestione e la pianificazione del territorio. Un esempio nella Sardegna sud-occidentale
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Influence of solar field recirculation on medium-size CSP performance
No full textThis paper aims to evaluate the influence of solar field recirculation on the performance of medium-size Concentrating Solar Power (CSP) systems. Different strategies regarding recirculation paths are proposed and then compared. In particular, cases for total or partial recirculation of the solar field mass flow (those passing through, as well as those bypassing the cold tank) are compared with a strategy of no recirculation during the operating phases that occur throughout the day. The comparative analysis has been carried out by considering three days with different weather conditions, with particular reference to the CSP plant of the Ottana Solar Facility (currently under construction in the industrial district of Ottana, Sardinia, Italy).
The results of this study show that partial recirculation of the solar field does not allow performance improvement of the CSP plant. Moreover, bypassing the cold tank in the recirculation path avoids a strong deterioration in performance. Differences between recirculation strategies become subtler for clear-sky days and, therefore, the present results can be very useful for improving the CSP performance, especially during mostly cloudy days
L’utilizzo della terra in diversi scenari di politica. Risultati di un modello farm/household
No full textI mercati dei fattori rappresentano una tematica centrale nell’analisi dello sviluppo dell’azienda e della vitalità del settore agricolo. Tra i differenti fattori produttivi, la terra è uno dei più studiati. Il mercato fondiario è imperfetto e ciò è dovuto alla bassa sostituibilità del bene, alla poca trasparenza e agli alti costi di transazione. È caratterizzato da un basso numero di transazioni, una dimensione locale ed, inoltre, é influenzato dalla struttura economica, politica e istituzionale che lo circonda. In particolare, la letteratura economica agraria ha evidenziato gli effetti della Politica agricola comune (Pac) sui mercati fondiari (Floyd 1965; Parsch et al. 1998; Latruffe et al., 2006; Ciaian et al., 2006; Bartolini et al., 2011) e in specifico è stato studiato il modo in cui la riforma della Pac ha cambiato questi effetti nel tempo.
La Pac attuale è molto differente rispetto quando nacque, passando da politiche orientate alla produzione per arrivare con la riforma del 2003 a una politica di supporto al reddito con l’introduzione del pagamento unico aziendale (Pua) . Oggi la Pac sta subendo un nuovo processo di riforma e, in ottobre 2011, sono state pubblicate le proposte ufficiali per la riforma post-2013. In Italia, si può prevedere il passaggio del regime di pagamento unico da una base storica a una regionalizzata.
L’obiettivo del presente lavoro è fornire un’analisi ex-ante dell’impatto della nuova componente regionalizzata dei pagamenti diretti sul mercato fondiario. L’articolo mira a contribuire alla comprensione dei meccanismi che legano la riforma della Pac e il comportamento dell’agricoltore attraverso un’analisi degli investimenti in terra sotto differenti scenari di politica. L’indagine è condotta, prima, sviluppando una’analisi teorica attraverso l’interpretazione delle curve di domanda di terra aziendali, e successivamente realizzando un’analisi empirica a livello aziendale con un modello di programmazione matematica
Angina of effort with a variable threshold: a unique entity due to different mechanisms?
No full textVariable threshold during exertion is a common feature in patients with chronic exertional angina. Changes in coronary vasomotor tone, when occurring at sites of critical narrowings, are a plausible explanation for variability of symptoms in these patients. However, the evidence supporting this hypothesis is still uncertain. Accordingly, we performed four computer assisted, multistage bicycle ergometer tests, without drugs, in 30 patients with chronic exertional angina, exercise induced ST depression, and a history of variable anginal threshold during exertion. Significant coronary artery disease was documented in each case by coronary arteriography. Patients were tested at the same time of day within a two week period. Comparison was made between each single test and the average of the remaining three. Time to 0.1 mV ST depression showed significant (+/- 20%) changes in 27 (90%) patients. Variability was shown in two out of four tests in 25 patients (83%), in three tests in 10 (33%), and in four tests in 2 (7%). Rate pressure product at 0.1 mV ST depression was concurrently changed (+/- 20%) in 20 patients (67%). Variability in two, three and four tests was observed in 7 (22%), 2 (7%) and 2 (7%) patients, respectively. Changes in time to 0.1 mV ST depression paralleled those in rate-pressure product at the onset of ischemia in 6 patients (22%) (dynamic ischemic threshold). Rate pressure product at 0.1 mV ST depression was unchanged despite variations in time to 0.1 mV ST depression in 10 patients (37%) (fixed ischemic threshold). The remaining 11 patients (41%) showed variable exercise tolerance associated with fixed (13 tests) and dynamic (13 tests) ischemic threshold.(ABSTRACT TRUNCATED AT 250 WORDS
The clinical impact of maternal weight on offspring health: lights and shadows in breast milk metabolome.
No full textIntroduction: Pre-pregnancy overweight and obesity, depending on maternal nutrition and metabolic state, can influence fetal, neonatal, and long-term offspring health, regarding cardio-metabolic, respiratory, immunological, and cognitive outcomes. Thus, maternal weight can act, through mechanisms not fully understood, on the physiology and metabolism of some fetal organs and tissues, to adapt themselves to the intrauterine environment and nutritional reserves. These effects can occur by modulating gene expression, neonatal microbiome, and through breastfeeding. Areas Covered: In this paper, we investigated the potential effects of metabolites found altered in breast milk (BM) of overweight/obese mothers, through an extensive review of metabolomics studies, and the potential short and long-term clinical effects in the offspring, especially overweight, glucose homeostasis, insulin resistance, oxidative stress, infections, immune processes, neurodevelopment. Expert Opinion: Metabolomics seems the ideal tool to investigate BM variation depending on maternal or fetal/neonatal factors. In particular, BM metabolome alterations according to maternal conditions were recently pointed out in cases of gestational diabetes, preeclampsia, intrauterine growth restriction and maternal overweight/obesity. In our opinion, even if BM is the food of choice in neonatal nutrition, the deepest comprehension of its composition in overweight/obese mothers could allow targeted supplementation, to improve offspring health and metabolic homeostasis
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