557 research outputs found
Community Supported Agriculture in the urban fringe: empirical evidence for project potentiality in the metropolitan area of Naples (Italy)
Urbanisation of city-side areas effects on farm land use and organisation are analysed in this study with the objective of seeking the most effective way to implement a Community Supported Agriculture (CSA) scheme. Specifically, we used a theoretical framework to describe and assess the relationships between urbanisation and changes in farm-styles in the city belt. Our analysis is based on a case study in the protected area of the Campi Flegrei Regional Park situated in the north-western part of the Neapolitan metropolitan area, which is a peri-urban rural area with severe environmental management problems. Our results from the empirical analysis allowed us to distinguish the farms of the area into three behavioural-social groups on the basis of specific features, in order to identify the best suited type of farm for the strategic implementation of the CSA. A market scenario was predicted for each of them without any intervention
Rat pial microvascular responses to melatonin during bilateral common carotid artery occlusion and reperfusion
The present study assessed the in vivo rat pial microvascular responses induced by melatonin during brain hypoperfusion and reperfusion (RE) injury. Pial microcirculation of male Wistar rats was visualized by fluorescence microscopy through a closed cranial window. Hypoperfusion was induced by bilateral common carotid artery occlusion (BCCAO, 30 min); thereafter, pial microcirculation was observed for 60 min. Arteriolar diameter, permeability increase, leukocyte adhesion to venular walls, perfused capillary length (PCL), and capillary red blood cell velocity (V(RBC) ) were investigated by computerized methods. Melatonin (0.5, 1, 2 mg/kg b.w.) was intravenously administered 10 min before BCCAO and at the beginning of RE. Pial arterioles were classified in five orders according to diameter, length, and branchings. In control group, BCCAO caused decrease in order 2 arteriole diameter (by 17.5 ± 3.0% of baseline) that was reduced by 11.8 ± 1.2% of baseline at the end of RE, accompanied by marked leakage and leukocyte adhesion. PCL and capillary V(RBC) decreased. At the end of BCCAO, melatonin highest dosage caused order 2 arteriole diameter reduction by 4.6 ± 2.0% of baseline. At RE, melatonin at the lower dosages caused different arteriolar responses. The highest dosage caused dilation in order 2 arteriole by 8.0 ± 1.5% of baseline, preventing leakage and leukocyte adhesion, while PCL and V(RBC) increased. Luzindole (4 mg/kg b.w.) prior to melatonin caused order 2 arteriole constriction by 12.0 ± 1.5% of baseline at RE, while leakage, leukocyte adhesion, PCL and V(RBC) were not affected. Prazosin (1 mg/kg b.w.) prior to melatonin did not significantly change melatonin's effects. In conclusion, melatonin caused different responses during hypoperfusion and RE, modulating pial arteriolar tone likely by MT1 and MT2 melatonin receptors while preventing blood-brain barrier changes through its free radical scavenging action
Protective Effects of Quercetin on Rat Pial Microvascular Changes during Transient Bilateral Common Carotid Artery Occlusion and Reperfusion
The aim of this study was to assess the in vivo effects of quercetin on pial microvascular responses during transient bilateral common carotid artery occlusion (BCCAO) and reperfusion. Rat pial microcirculation was visualized by fluorescence microscopy through a closed cranial window. Pial arterioles were classified in five orders of branchings. Capillaries were assigned order 0, the smallest arterioles order 1, and the largest ones order 5. In ischemic rats, 30 min BCCAO and 60 min reperfusion caused arteriolar diameter decrease (by 14.5 ± 3.3% of baseline in order 2), microvascular leakage [0.47 ± 0.04, normalized gray levels (NGL)], leukocyte adhesion in venules (9 ± 2/100 μm venular length, v.l./30 s), and reduction of capillary perfusion (by 40 ± 7% of baseline). Moreover, at the end of BCCAO and reperfusion there was a significant increase in reactive oxygen species (ROS) formation when compared with baseline. Quercetin highest dose determined dilation in all arteriolar orders (by 40 ± 4% of baseline in order 2) and prevented microvascular permeability (0.15 ± 0.02 NGL), leukocyte adhesion (3 ± 1/100 μm v.l./30 s) as well as ROS formation, while capillary perfusion was protected. Inhibition of endothelial nitric oxide synthase (NOS) prior to quercetin reduced arteriolar dilation (order 2 diameter increase by 10.3 ± 2.5% of baseline) and caused permeability increase (0.29 ± 0.03 NGL); inhibition of neuronal NOS or inducible NOS did not affect quercetin-induced effects. Inhibition of guanylyl cyclase prior to quercetin reversed the quercetin’s effects on pial arteriolar diameter and leakage. In conclusion, quercetin was able to protect pial microcirculation from ischemia–reperfusion damage inducing arteriolar dilation likely by nitric oxide release. Moreover, quercetin scavenger activity blunted ROS formation preserving the blood–brain barrier integrity
Rat Pial Microvascular Responses to Transient Bilateral Common Carotid Artery Occlusion and Reperfusion: Quercetin’s Mechanism of Action
The aim of the present study was to assess quercetin’s mechanism of action in rat pial microvessels during transient bilateral common carotid artery occlusion (BCCAO) and reperfusion. Rat pial microcirculation was visualized using fluorescence microscopy through a closed cranial window. Pial arterioles were classified in five orders of branchings. In ischemic rats, 30 min BCCAO and 60 min reperfusion caused arteriolar diameter decrease, microvascular leakage, leukocyte adhesion in venules, and reduction of capillary perfusion. Quercetin highest dose determined dilation in all arteriolar orders, by 40 ± 4% of baseline in order 2 vessels, and prevented microvascular permeability [0.15 ± 0.02 normalized gray levels (NGL)], leukocyte adhesion, and capillary failure. Protein kinase C (PKC) inhibition exerted by chelerythrine prior to quercetin attenuated quercetin-induced effects: order 2 arterioles dilated by 19.0 ± 2.4% baseline, while there was an increase in permeability (0.40 ± 0.05 NGL) and leukocyte adhesion with a marked decrease in capillary perfusion. Tyrosine kinase (TK) inhibition by tyrphostin 47 prior to quercetin lessened smaller pial arterioles responses, dilating by 20.7 ± 2.5% of baseline, while leakage increased (0.39 ± 0.04 NGL) sustained by slight leukocyte adhesion and ameliorated capillary perfusion. Inhibition of endothelium nitric oxide synthase (eNOS) by NG-nitro-L-arginine-methyl ester (L-NAME) prior to PKC or TK reduced the quercetin’s effects on pial arteriolar diameter and leakage. eNOS inhibition by L-NAME reduced quercetin effects on pial arteriolar diameter and leakage. Finally, combined inhibition of PKC and TK prior to quercetin abolished quercetin-induced effects, decreasing eNOS expression, while blocking ATP-sensitive potassium (KATP) channels by glibenclamide suppressed arteriolar dilation. In conclusion, the protective effects of quercetin could be due to different mechanisms resulting in NO release throughout PKC and TK intracellular signaling pathway activation
Long term remodeling of rat pial microcirculation after transient middle cerebral artery occlusion and reperfusion.
Objective: The aim of this study was to assess the in vivo structural and functional remodeling of pial arteriolar networks in the ischemic area of rats submitted to transient middle cerebral artery occlusion (MCAO) and different time intervals of reperfusion.
Methods and results: Two closed cranial windows were implanted above the left and right parietal cortex to observe pial microcirculation by fluorescence microscopy. The geometric characteristics of pial arteriolar networks, permeability increase, leukocyte adhesion and capillary density were analyzed after 1 h or 1, 7, 14 or 28 days of reperfusion. MCAO and 1-hour reperfusion caused marked microvascular changes in pial networks. The necrotic core was devoid of vessels, while the penumbra area presented a few arterioles, capillaries and venules with severe neuronal damage. Penumbra microvascular permeability and leukocyte adhesion were pronounced. At 7 days of reperfusion, new pial arterioles were organized in anastomotic vessels, overlapping the ischemic core and in penetrating pial arterioles. Vascular remodeling caused different arteriolar rearrangement up to 28 days of reperfusion and animals gradually regained their motor and sensory functions.
Conclusions: Transient MCAO-induced pial-network remodeling is characterized by arteriolar anastomotic arcades. Remodeling mechanisms appear to be accompanied by an increased expression of nitric oxide synthases
Reciprocal regulation of metabolic and signaling pathways
<p>Abstract</p> <p>Background</p> <p>By studying genome-wide expression patterns in healthy and diseased tissues across a wide range of pathophysiological conditions, DNA microarrays have revealed unique insights into complex diseases. However, the high-dimensionality of microarray data makes interpretation of heterogeneous gene expression studies inherently difficult.</p> <p>Results</p> <p>Using a large-scale analysis of more than 40 microarray studies encompassing ~2400 mammalian tissue samples, we identified a common theme across heterogeneous microarray studies evident by a robust genome-wide inverse regulation of metabolic and cell signaling pathways: We found that upregulation of cell signaling pathways was invariably accompanied by downregulation of cell metabolic transcriptional activity (and vice versa). Several findings suggest that this characteristic gene expression pattern represents a new principle of mammalian transcriptional regulation. First, this coordinated transcriptional pattern occurred in a wide variety of physiological and pathophysiological conditions and was identified across all 20 human and animal tissue types examined. Second, the differences in metabolic gene expression predicted the magnitude of differences for signaling and all other pathways, i.e. tissue samples with similar expression levels of metabolic transcripts did not show any differences in gene expression for all other pathways. Third, this transcriptional pattern predicted a profound effect on the proteome, evident by differences in structure, stability and post-translational modifications of proteins belonging to signaling and metabolic pathways, respectively.</p> <p>Conclusions</p> <p>Our data suggest that in a wide range of physiological and pathophysiological conditions, gene expression changes exhibit a recurring pattern along a transcriptional axis, characterized by an inverse regulation of major metabolic and cell signaling pathways. Given its widespread occurrence and its predicted effects on protein structure, protein stability and post-translational modifications, we propose a new principle for transcriptional regulation in mammalian biology.</p
Effects of physical exercise associated with a diet enriched with natural antioxidants on cerebral hypoperfusion and reperfusion injury in spontaneously hypertensive rats
Oxidative stress is implicated in the pathogenesis of arterial hypertension. The reduction in the bioavailability of nitric oxide (NO) causes endothelial dysfunction, altering the functions of cerebral blood vessels. Physical exercise and intake of antioxidants improve the redox state, increasing the vascular NO production and/or the decrease in NO scavenging by reactive oxygen species (ROS). The present study was aimed at assessing the effects of physical exercise associated with a diet enriched with antioxidants from the Annurca apple in preventing the microvascular damage due to cerebral hypoperfusion and reperfusion injury in spontaneously hypertensive rats (SHRs). The rat pial microcirculation was investigated by intravital fluorescence microscopy through a parietal closed cranial window. As expected, SHRs subjected to physical exercise or an antioxidants-enriched diet showed a reduction of microvascular permeability, ROS formation, and leukocyte adhesion to venular walls, with a major effect of the antioxidants-enriched diet, when compared to untreated SHRs. Moreover, capillary perfusion was preserved by both treatments in comparison with untreated SHRs. Unexpectedly, the combined treatments did not induce higher effects than the single treatment. In conclusion, our results support the efficacy of physical activity or antioxidant supplement in reducing the microvascular alterations due to hypertension and ascribe to an antioxidants-enriched diet effective microvascular protection in SHRs
Muscle expression of human retinol-binding protein (RBP). Suppression of the visual defect of RBP knockout mice.
Mice lacking retinol-binding protein (RBP) have low circulating retinol levels. They have severe visual defects due to a low content of retinol or retinyl esters in the eye. A transgenic mouse strain that expresses human RBP under the control of the muscle creatine kinase promoter in the null background was generated. The exogenous protein bound retinol and transthyretin in the circulation and effectively delivered retinol to the eye. Thus, RBP expressed from an ectopic source suppresses the visual phenotype, and retinoids accumulate in the eye. No human RBP was found in the retinal pigment epithelium of the transgenic mice, indicating that retinol uptake by the eye does not entail endocytosis of the carrier RBP
miR-27a is a master regulator of metabolic reprogramming and chemoresistance in colorectal cancer.
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