Angiogenesis (the growth of new capillaries) occurs in adults in response to physiological stimuli such as wound healing and exercise. The mitogen-activated protein kinase c-jun N-terminal kinase (JNK) has a controversial role in the process of angiogenesis, with previous evidence supporting JNK as both a positive and negative regulator of blood vessel growth. The purpose of this study was to clarify the role of JNK in the angiogenesis process. Phosphorylated JNK was observed in cultured endothelial cells, and levels were constant regardless of extracellular matrix composition. Using SP600125, inhibition of JNK attenuated sprout growth in 3D capillary sprout cultures. Inhibition of JNK reduced endothelial cell proliferation and migration in vitro. JNK inhibition and siRNA knockdown of c-jun (a downstream target of JNK) decreased protein levels of the transcription factor Egr-1, a regulator of genes involved in proliferation and migration. Matrix metalloproteinase-2 (MMP-2) production, and activity also, was reduced in sprout cultures treated with SP600125. c-Jun silencing decreased both MMP-2 and membrane type-1 (MT1)-MMP mRNA in endothelial cells, implicating both JNK and c-jun as activators of proteolysis. Taken together, these results provide evidence that JNK and its downstream target c-jun positively regulate angiogenesis via activation of endothelial cell proliferation, migration and proteolysis.

These results suggest a link through which flow-mediated endothelial-derived signals may promote myocyte production of VEGF-A. In turn, myocyte-derived VEGF-A is required for appropriate flow-mediated microvascular remodelling. This highlights the importance of the local environment and paracrine interactions in the regulation of tissue perfusion.

Elevated shear stress within the skeletal muscle microvasculature is implicated in the induction of a longitudinal splitting form of angiogenesis, which is characterized by the lack of basement membrane breakage. We investigated whether the transcriptional regulator, Ets-1, is responsive to changes in hemodynamic forces and if so, whether Ets-1 controls microvascular endothelial cell integrity by inducing the expression of inhibitors of matrix degrading proteases. Rats were treated with prazosin for 2, 4 and 7 days to increase in microvascular shear stress in hindlimb skeletal muscles. In complimentary in vitro experiments, rat microvascular skeletal muscle endothelial cells were exposed to laminar shear stress (15 dyne/cm 2 ) for 0.5, 2, and 24 hours. TaqMan PCR analysis of laser microdissected capillaries isolated from EDL muscles demonstrated transient (after 2 days) induction of Ets-1 gene expression. In cultured cells, a transient up-regulation of Ets-1 mRNA was observed after 2hr shear stimulation, accompanied by increased phosphorylation of Ets-1 and enhanced Ets-1 DNA binding activity. This response was modulated by ERK1/2 and p38 MAP kinases, but was not dependent on NOS or COX-2 activity. PAI-1, TIMP-1 and TIMP-3 mRNA were elevated significantly in prazosin treated EDL, and in response to shear stimulation in vitro. In cultured endothelial cells, Ets-1 RNA interference abolished the shear-induced increases in Ets-1, PAI-1, TIMP-1 and TIMP-3 mRNA expression. These results suggest that enhanced laminar shear stress may act to preserve the integrity of microvascular walls in part through Ets-1-dependent induction of protease inhibitors.

Peripheral artery disease is characterized by reduced blood flow to the lower limb, resulting in chronic ischemia in these muscles, which can lead to eventual amputation of the affected limb. Stimulation of angiogenesis in the ischemic region would be of therapeutic benefit; however, attempts to increase angiogenesis through delivery of vascular endothelial growth factor (VEGF) largely have been unsuccessful. Recent studies have shown that VEGF signaling through its receptors, VEGFR1 and VEGFR2, is much more complex than previously appreciated. This review will examine current research into the function of VEGFR1 and -2 signaling pathways, and evidence of cross-talk between these two receptors. The potential impact of endothelial cell co-stimulation via other growth factors/cell surface receptors (such as angiopoietins and ephrins) on angiogenesis also will be discussed. Evidence suggesting deficiencies in VEGF pathway signaling in individuals with chronic ischemia and diabetes will be discussed. Numerous pro-angiogenic therapies for ischemia have been employed. The successes and limitations of these therapies will be illustrated, emphasizing more recent angiogenesis therapies that focus on activating co-ordinated patterns of pro-angiogenic genes as the most promising direction in the treatment of ischemic muscle tissue in peripheral artery disease.

The efficacy and tolerability of moclobemide and fluvoxamine, two new types of antidepressant agents, were compared in a multicentre, double-blind prospective study of patients with a diagnosis of major depressive episode (DSM III). Patients were randomized to receive either moclobemide (150 mg) or fluvoxamine (50 mg) twice daily for 7 days, immediately following a washout period of at least 1 week. Dosages were increased where necessary on day 8, to a maximum of moclobemide 450 mg or fluvoxamine 200 mg and in most cases were maintained at these levels for the remainder of the study period (4-6 weeks). Both treatment groups showed a marked antidepressant effect. While both treatments were well tolerated, moclobemide showed a more favourable side-effect profile than fluvoxamine. Of the 126 patients eligible for evaluation, 34 withdrew from therapy, 22% in the moclobemide group and 30% in the fluvoxamine group. Adverse events were reported in 41.8% of patients treated with moclobemide compared to 60.3% of patients in the fluvoxamine group. Reports of dry mouth and other anticholinergic effects were more frequent among those treated with fluvoxamine. A greater number of gastrointestinal complaints, especially nausea, also occurred in the fluvoxamine-treated patients.