Background-AMP-activated protein kinase (AMPK) is a stress-activated protein kinase that works as a metabolic sensor of cellular ATP levels. Here, we investigated whether AMPK signaling has a role in the regulation of the angiotensin II (Ang II)-induced proliferation signal in rat vascular smooth muscle cells (VSMCs

PurposeThe purpose was to clarify the load-bearing functions of the fibers of the femoral anterior cruciate ligament (ACL) attachment in resisting tibial anterior drawer and rotation.MethodsA sequential cutting study was performed on 8 fresh-frozen human knees. The femoral attachment of the ACL was divided into a central area that had dense fibers inserting directly into the femur and anterior and posterior fan-like extension areas. The ACL fibers were cut sequentially from the bone: the posterior fan-like area in 2 stages, the central dense area in 4 stages, and then the anterior fan-like area in 2 stages. Each knee was mounted in a robotic joint testing system that applied tibial anteroposterior 6-mm translations and 10° or 15° of internal rotation at 0° to 90° of flexion. The reduction of restraining force or moment was measured after each cut.ResultsThe central area resisted 82% to 90% of the anterior drawer force; the anterior fan-like area, 2% to 3%; and the posterior fan-like area, 11% to 15%. Among the 4 central areas, most load was carried close to the roof of the intercondylar notch: the anteromedial bundle resisted 66% to 84% of the force and the posterolateral bundle resisted 16% to 9% from 0° to 90° of flexion. There was no clear pattern for tibial internal rotation, with the load shared among the posterodistal and central areas near extension and mostly the central areas in flexion.ConclusionsUnder the experimental conditions described, 66% to 84% of the resistance to tibial anterior drawer arose from the ACL fibers at the central-proximal area of the femoral attachment, corresponding to the anteromedial bundle; the fan-like extension fibers contributed very little. This work did not support moving a single-bundle ACL graft to the side wall of the notch or attempting to cover the whole attachment area if the intention was to mimic how the natural ACL resists tibial displacements.Clinical RelevanceThere is ongoing debate about how best to reconstruct the ACL to restore normal knee function, including where is the best place for ACL graft tunnels. This study found that the most important area on the femur, in terms of resisting displacement of the tibia, was in the central-anterior part of the femoral ACL attachment, near the roof of the intercondylar notch. The testing protocol did not lead to data that would support using a large ACL graft tunnel that attempts to cover the whole natural femoral attachment area.

We examined whether ANG II and TNF-alpha cooperatively induce vascular inflammation using the expression of monocyte chemoattractant protein (MCP)-1 as a marker of vascular inflammation. ANG II and TNF-alpha stimulated MCP-1 expression in a synergistic manner in vascular smooth muscle cells. ANG II-induced MCP-1 expression was potently inhibited to a nonstimulated basal level by blockade of the p38-dependent pathway but only partially inhibited by blockade of the NF-kappaB-dependent pathway. In contrast, TNF-alpha-induced MCP-1 expression was potently suppressed by blockade of NF-kappaB activation but only modestly suppressed by blockade of p38 activation. ANG II- and TNF-alpha-induced activation of NF-kappaB- and p38-dependent pathways was partially inhibited by pharmacological inhibitors of ROS production. Furthermore, ANG II- and TNF-alpha-stimulated MCP-1 expression was partially suppressed by ROS inhibitors. We also examined whether endogenous ANG II and TNF-alpha cooperatively promote vascular inflammation in vivo using a wire injury model of the rat femoral artery. Blockade of both ANG II and TNF-alpha further suppressed neointimal formation, macrophage infiltration, and MCP-1 expression in an additive manner compared with blockade of ANG II or TNF-alpha alone. These results suggested that ANG II and TNF-alpha synergistically stimulate MCP-1 expression via the utilization of distinct intracellular signaling pathways (p38- and NFkappaB-dependent pathways) and that these pathways are activated in ROS-dependent and -independent manners. These results also suggest that ANG II and TNF-alpha cooperatively stimulate vascular inflammation in vivo as well as in vitro.

Growth hormone and IGF-1 have been suggested to have tissue-protective effects. Ghrelin is a stomach-derived growth hormone secretagogue. The effects of ghrelin on ischemia/reperfusion-induced renal failure in mice were examined. Ischemic acute renal failure was induced by bilateral renal artery clamping for 45 min and reperfusion for 24 h. Ghrelin (100 g/kg mouse) or vehicle was injected subcutaneously six times before surgery and three times after surgery every 8 h. Twenty-four hours after reperfusion, the right kidney was isolated and perfused. Acetylcholine (ACh)-and adrenomedullin-induced endothelium-dependent vasorelaxation of renal vessels significantly improved in ghrelin-pretreated mice (%⌬ renal perfusion pressure by 10 ؊7 M ACh ؊63.5 ؎ 3.7 versus ؊41.2 ؎ 5.5%; P < 0.05). This change was associated with significant increases of nitric oxide release in the kidneys of ghrelin-treated mice (10 ؊7 M ACh 35.5 ؎ 5.8 versus 16.9 ؎ 3.5 fmol/g kidney per min; P < 0.05). Serum concentration of urea nitrogen (53 ؎ 7 versus 87 ؎ 15 mg/dl; P < 0.05) and renal injury score were significantly lower in the ghrelin group (2.5 ؎ 0.8 versus 5.3 ؎ 1.5; P < 0.01). Tubular apoptotic index was significantly lower in the ghrelin group (5 ؎ 5 versus 28 ؎ 4; P < 0.05). Furthermore, the survival rate after the 60-min ischemic period was higher in the ghrelin group (80 versus 20%; P < 0.05). Ghrelin treatment significantly increased the serum level of IGF-1. However, such renal protective effects of ghrelin on ischemia/reperfusion injury were not observed in insulin receptor substrate-2 knockout mice. These results suggest that ghrelin may protect the kidneys from ischemia/reperfusion injury and that this effect is related to an improvement of endothelial function through an IGF-1-mediated pathway.

Abstract-Although it has been established that myocyte enhancer factor 2 (MEF2) plays pivotal roles in the development of the cardiovascular system as well as skeletal muscle cells, little is known of its role in vascular inflammatory diseases such as atherosclerosis and restenosis after angioplasty. To investigate the role of MEF2 in vascular inflammation and that of p38 in the activation of MEF2, we infected cultured rat vascular smooth muscle cells (VSMCs) with an adenovirus construct expressing a dominant-negative mutant of MEF2A (MEF2ASA) or mitogen-activated protein kinase kinase 6 (MEK6AA), and examined their effects on the expression of monocyte chemoattractant protein-1 (MCP-1), which is known to play important roles in vascular inflammation. We also examined the role of MEF2 in vivo using a rat model of transluminal wire-induced injury of the femoral artery. Angiotensin II (Ang II)-induced expression of MCP-1 mRNA was significantly inhibited by infection with adenoviruses encoding MEF2ASA (AdMEF2ASA) or MEK6AA. Ang II-induced increase of MCP-1 promoter activity was also significantly suppressed by overexpression of MEF2ASA or MEK6AA. Ang II stimulated the transactivating function of MEF2A and this activation was inhibited by overexpression of MEK6AA. Infection with AdMEF2ASA suppressed MCP-1 expression in the femoral artery after the transluminal mechanical injury. AdMEF2ASA infection also inhibited macrophages infiltration and neointimal formation in the wire-injured femoral arteries. These results suggested that MEF2 activation via the p38-dependent pathway mediates vascular inflammation via stimulation of MCP-1 expression in VSMCs and macrophages infiltration. Key Words: atherosclerosis Ⅲ angioplasty Ⅲ angiotensin Ⅲ signal transduction Ⅲ inflammation I t has recently become clear that inflammation mediated by chemokines plays pivotal roles in the initiation and maintenance of vascular diseases such as atherosclerosis and restenosis after angioplasty. 1 Among a variety of chemokines, monocyte chemoattractant protein-1 (MCP-1) is reportedly critically implicated in the development of vascular diseases. MCP-1 is widely expressed in atherosclerotic lesions including vascular endothelial cells, smooth muscle cells, and macrophages. 2 It has been reported that the additional disruption of the MCP-1 receptor markedly attenuated atherosclerotic lesions by inhibiting macrophage infiltration in apolipoprotein E null mice. 3 It has also been shown that neutralization of MCP-1 is effective in preventing restenosis after angioplasty. 4 Intracellular signaling pathways leading to the activation of the MCP-1 gene have been intensively studied. Protein kinases including extracellular signalregulated kinase (ERK), p38, and janus kinase (JAK) appear to be involved in the induction of MCP-1 expression. 5-8 A variety of nuclear factors such as nuclear factor-B (NF-B), SP-1, AP-1, and signal transducers and activators of transcription (STAT) have been shown to be implicated in the transcriptional activation of the MCP-1...