Smooth Muscle-Generated Methylglyoxal Impairs Endothelial Cell-Mediated Vasodilatation of Cerebral Microvessels in Type 1 Diabetic Rats

Background and Purpose Endothelial cell-mediated vasodilatation of cerebral arterioles is impaired in individuals with Type 1 diabetes (T1D). This defect compromises haemodynamics and can lead to hypoxia, microbleeds, inflammation and exaggerated ischaemia-reperfusion injuries. The molecular causes for dysregulation of cerebral microvascular endothelial cells (cECs) in T1D remains poorly defined. This study tests the hypothesis that cECs dysregulation in T1D is triggered by increased generation of the mitochondrial toxin, methylglyoxal, by smooth muscle cells in cerebral arterioles (cSMCs). Experimental Approach Endothelial cell-mediated vasodilatation, vascular transcytosis inflammation, hypoxia and ischaemia-reperfusion injury were assessed in brains of male Sprague-Dawley rats with streptozotocin-induced diabetes and compared with those in diabetic rats with increased expression of methylglyoxal-degrading enzyme glyoxalase-I (Glo-I) in cSMCs. Key Results After 7–8 weeks of T1D, endothelial cell-mediated vasodilatation of cerebral arterioles was impaired. Microvascular leakage, gliosis, macrophage/neutrophil infiltration, NF-κB activity and TNF-α levels were increased, and density of perfused microvessels was reduced. Transient occlusion of a mid-cerebral artery exacerbated ischaemia-reperfusion injury. In cSMCs, Glo-I protein was decreased, and the methylglyoxal-synthesizing enzyme, vascular adhesion protein 1 (VAP-1) and methylglyoxal were increased. Restoring Glo-I protein in cSMCs of diabetic rats to control levels via gene transfer, blunted VAP-1 and methylglyoxal increases, cECs dysfunction, microvascular leakage, inflammation, ischaemia-reperfusion injury and increased microvessel perfusion. Conclusions and Implications Methylglyoxal generated by cSMCs induced cECs dysfunction, inflammation, hypoxia and exaggerated ischaemia-reperfusion injury in diabetic rats. Lowering methylglyoxal produced by cSMCs may be a viable therapeutic strategy to preserve cECs function and blunt deleterious downstream consequences in T1D

Dose-Dependent Influences of Ethanol on Ischemic Stroke: Role of Inflammation

Chronic ethanol consumption dose-dependently affects both incidence and prognosis of ischemic stroke. Our goal was to determine whether the influence of chronic ethanol consumption on ischemic stroke is related to an altered inflammatory profile in the brain. Male C57BL/6J mice were divided into six groups and gavage fed with 0.175, 0.35, 0.7, 1.4, 2.8 g/kg/day ethanol or volume-matched water once a day for 8 weeks. Adhesion molecules, microglial activation, neutrophil infiltration, pro- and anti-inflammatory cytokines/chemokines, blood-brain barrier (BBB) permeability, and matrix metallopeptidases (MMPs) in the cerebral cortex before and following a 90-min unilateral middle cerebral artery occlusion (MCAO)/24-h reperfusion were evaluated. Brain ischemia/reperfusion (I/R) injury was significantly reduced in 0.7 g/kg/day ethanol group (peak blood ethanol concentration: 9 mM) and worsened in 2.8 g/kg/day ethanol group (peak blood ethanol concentration: 37 mM). Baseline E-selectin was downregulated in all ethanol groups, whereas baseline intercellular adhesion molecule-1 (ICAM-1) was only downregulated in 0.35 and 0.7 g/kg/day ethanol groups. Interestingly, baseline vascular cell adhesion molecule-1 (VCAM-1) was upregulated in 0.35, 0.7, and 1.4 g/kg/day ethanol groups. Post-ischemic upregulation of ICAM-1 and E-selectin were suppressed in all ethanol groups. Post-ischemic neutrophil infiltration and microglial activation were significantly less in the low-moderate (0.175–1.4 g/kg/day) ethanol groups but greater in the 2.8 g/kg/day ethanol group compared to the vehicle group. At basal conditions, ethanol increased one pro- and two anti-inflammatory cytokines/chemokines at the 0.7 g/kg/day dose, and 13 pro- and eight anti-inflammatory cytokines/chemokines at the 2.8 g/kg/day dose. After ischemia, 0.7 g/kg/day ethanol suppressed post-ischemic pro-inflammatory cytokines/chemokines and enhanced post-ischemic anti-inflammatory cytokines/chemokines. Moreover, 0.7 g/kg/day ethanol significantly reduced baseline MMP-9 activity and alleviated post-ischemic BBB breakdown. On the other hand, 2.8 g/kg/day ethanol worsened post-ischemic BBB breakdown. Our findings suggest that low-moderate ethanol consumption may prevent ischemic stroke and reduce brain I/R injury by suppressing inflammation, whereas heavy alcohol consumption may induce ischemic stroke and worsen brain I/R injury by aggravating inflammation

Lipopolysaccharide-induced blood-brain barrier disruption: roles of cyclooxygenase, oxidative stress, neuroinflammation, and elements of the neurovascular unit

Background: Disruption of the blood-brain barrier (BBB) occurs in many diseases and is often mediated by inflammatory and neuroimmune mechanisms. Inflammation is well established as a cause of BBB disruption, but many mechanistic questions remain. Methods: We used lipopolysaccharide (LPS) to induce inflammation and BBB disruption in mice. BBB disruption was measured using 14C-sucrose and radioactively labeled albumin. Brain cytokine responses were measured using multiplex technology and dependence on cyclooxygenase (COX) and oxidative stress determined by treatments with indomethacin and N-acetylcysteine. Astrocyte and microglia/macrophage responses were measured using brain immunohistochemistry. In vitro studies used Transwell cultures of primary brain endothelial cells co- or tri-cultured with astrocytes and pericytes to measure effects of LPS on transendothelial electrical resistance (TEER), cellular distribution of tight junction proteins, and permeability to 14C-sucrose and radioactive albumin. Results: In comparison to LPS-induced weight loss, the BBB was relatively resistant to LPS-induced disruption. Disruption occurred only with the highest dose of LPS and was most evident in the frontal cortex, thalamus, pons-medulla, and cerebellum with no disruption in the hypothalamus. The in vitro and in vivo patterns of LPS-induced disruption as measured with 14C-sucrose, radioactive albumin, and TEER suggested involvement of both paracellular and transcytotic pathways. Disruption as measured with albumin and 14C-sucrose, but not TEER, was blocked by indomethacin. N-acetylcysteine did not affect disruption. In vivo, the measures of neuroinflammation induced by LPS were mainly not reversed by indomethacin. In vitro, the effects on LPS and indomethacin were not altered when brain endothelial cells (BECs) were cultured with astrocytes or pericytes. Conclusions: The BBB is relatively resistant to LPS-induced disruption with some brain regions more vulnerable than others. LPS-induced disruption appears is to be dependent on COX but not on oxidative stress. Based on in vivo and in vitro measures of neuroinflammation, it appears that astrocytes, microglia/macrophages, and pericytes play little role in the LPS-mediated disruption of the BBB

Plasma-deposited Polymer Films III. The Effects of Gamma Irradiation

The results of a study of irradiated and unirradiated samples of polymers prepared by plasma polymerization in an inductively coupled radiofrequency (rf) reactor using infrared, elemental, thermogravimetric, and ESR analyses and density refractive index measurements are presented. the plasma-formed polymers studied include polypropylene, poly(ethylbenzene), poly(methyl methacrylate), poly(tetrafluoroethylene), poly(chlorotrifluoroethylene), and poly(trimethylchlorosilane). in experiments, characterization of both irradiated and unirradiated plasma-formed polymer films was carried out to determine chemical and/or physical property changes occurring as a consequence of radiation. Analysis of these data suggests that irradiation may provide a means of quenching free-radical sites

Organic Desorption from Carbon. III. The effect of solvent in the desorption of phenol from dry carbon

The desorption of phenol from active carbon was studied using a continuous flow desorber. The system used was nearly water free to reduce water phenol interactions. An attempt to correlate the desorption data with the physical properties of phenol and solvents, in addition to regular solution theory, proved unsuccessful. A thermodynamic approach using the linear free energy enthalpy relationship produced a general trend by using the heat of solution for phenol in solution and a reasonable correlation using the heat of formation of the phenol solvent hydrogen bond with the desorption data