Objective— Arginase can reduce NO availability. In this study, we explored arginase as a determinant of endothelial dysfunction in small arteries from obese patients and its relationship with aging and microvascular remodeling. Approach and Results— Small arteries were dissected after subcutaneous fat biopsies and evaluated on a pressurized micromyograph. Endothelium-dependent vasodilation was assessed by acetylcholine, repeated under L-NAME ( N   G -nitro-L-arginine-methyl ester), N(ω)-hydroxy-nor- l -arginine (arginase inhibitor) and gp91ds-tat (NADPH [nicotinamide adenine dinucleotide phosphate oxidase] oxidase inhibitor) in vessels from young (age <30 years) control and obese and old (>30 years) control and obese subjects. Media-lumen ratio and amount of vascular wall fibrosis were used as markers of vascular remodeling. Amount of vascular superoxide anions and NO production were determined with immunofluorescence, whereas arginase expression was quantified using Western blot and quantitative polymerase chain reaction. Obese and older age groups had lower vascular NO, as well as higher media-lumen ratio, wall fibrosis, intravascular superoxide, and blunted inhibitory effect of L-NAME on acetylcholine versus controls and younger age groups. N(ω)-hydroxy-nor- l -arginine restored the acetylcholine-induced vasodilation in young and, to a lesser extent, in old obese subjects. This effect was abolished by addition of L-NAME. Gp91ds-tat increased the vasodilatory response to N(ω)-hydroxy-nor- l -arginine in old obese. Superoxide anions and arginase I/II levels were higher in the vascular wall of obese versus controls. Conclusions— Arginase contributes to microvascular endothelial dysfunction in obesity. Its impact is reduced by aging because of higher levels of vascular oxidative stress. Obesity is accompanied by accelerated microvascular remodeling, the extent of which is related to the amount of arginase in the vascular wall.

Background and Purpose-We sought to determine whether the introduction of EEG monitoring during head-up tilt testing could significantly improve the understanding of the cerebral events occurring during tilt-induced vasovagal syncope and the potential danger to the patient of this diagnostic procedure. Methods-EEG monitoring was performed during head-up tilt testing in a group of 63 consecutive patients (27 males and 36 females; mean age, 41.5 years) with a history of recurrent syncope of unknown origin despite extensive clinical and laboratory assessment. Results-Syncope occurred in 27 of 63 patients (42.8%) during head-up tilt testing and was found to be cardioinhibitory in 11 of 27 (40.7%) and vasodepressor in 16 of 27 (59.3%). All patients with a negative response to head-up tilt testing showed no significant EEG modifications. In patients with vasodepressor syncope, a generalized high-amplitude, 4-to 5-Hz (theta range) slowing of EEG activity appeared at the onset of syncope, followed by an increase of brain-wave amplitude with the reduction of frequency at 1.5 to 3 Hz (delta range). The return to the supine position was associated with brain-wave amplitude reduction and frequency increase to 4 to 5 Hz, followed by restoration of a normal EEG pattern and arousal (mean total duration of syncope, 23.2 seconds.). In patients with cardioinhibitory syncope, a generalized high-amplitude EEG slowing in the theta range was noted at the onset of syncope, followed by a brain-wave amplitude increase and slowing in the delta range. A sudden reduction of brain-wave amplitude then ensued, leading to the disappearance of electrocerebral activity ("flat" EEG). The return to the supine position did not allow either the immediate resolution of EEG abnormalities or consciousness recovery, both of which occurred after a further time interval (mean total duration of syncope, 41.4 seconds.). Conclusions-EEG monitoring during head-up tilt testing allowed recording and systematic description of electrocerebral abnormalities developing in the course of tilt-induced vasovagal syncope.

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Purpose: Luteolin exerts beneficial effects against obesity-associated comorbidities, although its influence on vascular dysfunction remains undetermined. We examined the effects of luteolin on endothelial dysfunction in a mouse model of diet-induced obesity.Methods: Standard diet (SD) or high-fat diet (HFD)-fed mice were treated daily with luteolin intragastrically. After 8 weeks, body and epididymal fat weight, as well as blood cholesterol, glucose, and triglycerides were evaluated. Endothelium-dependent relaxations of resistance mesenteric vessels was assessed by a concentration-response curve to acetylcholine, repeated upon Nw-nitro-L-arginine methylester (L-NAME) or ascorbic acid infusion to investigate the influence of nitric oxide (NO) availability and reactive oxygen species (ROS) on endothelial function, respectively. Intravascular ROS production and TNF levels were measured by dihydroethidium dye and ELISA, respectively. Endothelial NO synthase (eNOS) and superoxide dismutase 1 (SOD1), as well as microRNA-214-3p expression were examined by Western blot and RT-PCR assays, respectively.Results: HFD animals displayed elevated body weight, epididymal fat weight and metabolic indexes. Endothelium-dependent relaxation was resistant to L-NAME and enhanced by ascorbic acid, which restored also the inhibitory effect of L-NAME, suggesting a ROS-dependent reduction of NO availability in HFD vessels. Moreover, media-lumen ratio, intravascular superoxide anion and TNF levels were increased, while vascular eNOS, SOD1, and microRNA-214-3p expression were decreased. In HFD mice, luteolin counteracted the increase in body and epididymal fat weight, and metabolic alterations. Luteolin restored vascular endothelial NO availability, normalized the media-lumen ratio, decreased ROS and TNF levels, and normalized eNOS, SOD1 and microRNA-214-3p expression.Conclusion: Luteolin prevents systemic metabolic alterations and vascular dysfunction associated with obesity, likely through antioxidant and anti-inflammatory mechanisms.

Enteric neurogenic/inflammation contributes to bowel dysmotility in obesity. We examined the role of NLRP3 in colonic neuromuscular dysfunctions in mice with high-fat diet (HFD)-induced obesity.Experimental Approach: Wild-type C57BL/6J and NLRP3-KO (Nlrp3 À/À ) mice were fed with HFD or standard diet for 8 weeks. The activation of inflammasome pathways in colonic tissues from obese mice was assessed. The role of NLRP3 in in vivo colonic transit and in vitro tachykininergic contractions and substance P distribution was evaluated. The effect of substance P on NLRP3 signalling was tested in cultured cells.Key Results: HFD mice displayed increased body and epididymal fat weight, cholesterol levels, plasma resistin levels and plasma and colonic IL-1β levels, colonic inflammasome adaptor protein apoptosis-associated speck-like protein containing caspase-recruitment domain (ASC) and caspase-1 mRNA expression and ASC immunopositivity in macrophages. Colonic tachykininergic contractions were enhanced in HFD mice. HFD NLRP3 À/À mice developed lower increase in body and epididymal fat weight, cholesterol levels, systemic and bowel inflammation. In HFD Nlrp3 À/À mice, the functional alterations of tachykinergic pathways and faecal output were normalized. In THP-1 cells, substance P promoted IL-1β release. This effect was inhibited upon incubation with caspase-1 inhibitor or NK 1 antagonist and not observed in ASC À/À cells.Abbreviations: ASC, apoptosis-associated speck-like protein containing a caspase-recruitment domain; HFD, high-fat diet; IL-1β, interleukin-1beta; L-NAME, N ωnitro-L-arginine methylester; LPS, lipopolysaccharide; MyD88, adaptor molecule myeloid differentiation primary response 88; NLRP3, nucleotide-binding oligomerization domain leucine rich repeat and pyrin domain containing protein 3; SD, standard diet; WT, wild type.Carolina Pellegrini and Matteo Fornai equally contributed to the manuscript.