Current Neurovascular Research - Volume 6, Issue 3, 2009

To evaluate the anti-angiogenic efficacy of CB-12181 [an azasugar derivative that has inhibitory actions against matrix metalloproteinases (MMPs) and tumor necrosis factor-α (TNF-α) converting enzyme (TACE)], we investigated the suppressing ability on in vitro (tube formation by endothelial cells) and in vivo (retinal neovascularization on murine ischemia-induced proliferative retinopathy) models of angiogenesis. For in vitro analysis, a capillary-like tube formation model using human umbilical vein endothelial cells (HUVECs) and fibroblasts co-culture assay was employed. Tube formation of HUVECs was stimulated by vascular endothelial growth factor (VEGF) and incubated with different concentrations of CB-12181 (0.1-100 μM) for 11 days. For in vivo analysis, mice were exposed to 75% oxygen between postnatal days 7 and 12 (P7 to P12). Then, the mice were removed from the oxygen treatment and treated with CB-12181 (1, 15, or 50 mg/kg) by daily subcutaneous injection from the time of reintroduction to room air at P12 until P16. At P17, pathological and physiological angiogenesis was quantified using retinal flat-mounts visualized by fluorescent angiography. In the in vitro angiogenesis model, CB-12181 significantly suppressed VEGF-induced HUVEC tube formation. Furthermore, in the in vivo angiogenesis model, administration of CB-12181 significantly suppressed retinal neovascularization without any apparent side effects on physiological revascularization to the oxygen-induced obliteration area. These results suggest that CB-12181 might be useful in the treatment of various diseases that depend on pathologic angiogenesis, and especially valuable for the treatment of diabetic retinopathy and retinopathy of prematurity.

Near Infrared Spectroscopy (NIRS) is an emerging technique for brain oxygenation monitoring in newborns complicated by acute and chronic hypoxia. However, data regarding cerebral oxygenation normal values are still lacking and matter of debate. Therefore, we investigate whether NIRS parameters in healthy preterm/term infants are gestational age and delivery modalities dependent and correlated with standard monitoring parameters. From January to December 2007, 100 healthy newborns with gestational age from 30 to 42 weeks' gestation were evaluated. Routine laboratory variables, daily clinical and neurological evaluation and ultrasound imaging were performed. The regional cerebral oxygen saturation (rSO2) and fractional cerebral tissue oxygen extraction (FTOE) were measured by NIRS in the first 6- hours after birth. Data were recorded by MetaVision ICU X-Edition software and analyzed by SPSS statistical package. rSO2 and FTOE correlated (R=-0.77; R=0.41; P<0.01, for both) with gestational age. Highest rSO2 and the lowest FTOE peaks (P<0.001, for all) were found at 30-33 wks when compared with other monitoring periods. From 34 wks onwards, rSO2 progressively decreased and FTOE increased reaching their lower dip/peak (P<0.001, for all) at 38-39 weeks. rSO2 and FTOE values were significantly different (P<0.05, for both) between preterm and term newborns when corrected for delivery modality. rSO2 correlated (P<0.001 for all) with heart (r=0.63), respiratory (r=-0.58) rate, and with arterial oxygen saturation (r=0.65). In conclusion, in the first 6-hours after birth cerebral oxygenation in healthy newborns is gestational age-dependent and correlated with routine parameters. NIRS reference curve could be particularly useful in sick newborns brain monitoring.

White matter lesions (WML) are a frequent finding on brain magnetic resonance imaging scans. Elevated blood pressure (BP) is consistently identified as risk factor for WML. However, it is unknown whether BP still is associated with WML in patients manifesting vascular disease. The aim of this cross-sectional study was to investigate associations between BP and WML in patients manifesting vascular disease. A total of 1030 patients with vascular disease (cerebrovascular disease (23%), coronary heart disease (59%), peripheral arterial disease (23%), abdominal aortic aneurysm (9%)) from the Second Manifestations of Arterial Disease study were included. WML volume was calculated using an automated quantitative volumetric method and subsequently divided into quartiles. We investigated associations between BP and WML and examined whether relations between BP and WML were modified by the localisation of the symptomatic site or presence of diabetes. Participants had a mean age of 58.7 years. Median volume of WML was 1.70 ml. Mean BP was 141/82 mmHg and 69% suffered hypertension. No significant associations between systolic BP, diastolic BP, mean arterial pressure (MAP) or hypertension presence and moderate or large WML volumes were present. The relation between BP and WML was not modified by the localisation of vascular disease or diabetes presence. Among patients manifesting vascular disease, BP was not associated with the presence of WML, irrespective of the presence of diabetes or the localisation of vascular disease.

Stroke has been shown to lead to depressive disorders, anxiety disorders and other emotional consequences. Although the cause of these disorders is a subject of debate, stroke has clearly been shown to lead to the production of pro-inflammatory cytokines, which we hypothesized to play a role in the production of post-stroke emotional disorders. Thus we investigated here whether acute stroke might be associated with changes in the normal serum levels of IL-18 and if these changes were related to stroke severity, as well as to the presence and severity of alexithymia and depression. Thirty patients with a first-ever symptomatic ischemic stroke were included. Alexithymia (Toronto Alexithymia Scale; TAS-20), depression (Hamilton Depression Rating Scale; HDRS-17) and serum IL-18 were assessed. Stroke patients showed serum levels of IL-18 significantly related to stroke severity. Furthermore, a strong positive correlation was observed between IL-18 levels and severity of alexithymia, particularly among patients with right-hemisphere lesions. Specifically, circulating concentrations of IL-18 were significantly increased in patients with categorical alexithymia (TAS-20 score ≥61), as compared with both non alexithymic patients and control subjects. In addition, stroke was more severe in alexithymic patients, as compared to non alexithymic patients. Following multivariate regression, serum IL-18 levels appeared to be specifically associated with alexithymia rather than with stroke severity in patients with righthemisphere lesions only. These results suggest that IL-18 might be specifically implicated in the pathogenesis of poststroke alexithymia, ultimately contributing to impaired recovery from stroke.

Thapsigargin is a pro-apoptotic chemical, which has been shown to be useful to study cell death of cholinergic or dopaminergic neurons, or cells, which degenerate in Alzheimer's disease or Parkinson's disease, respectively. The aim of the present work was to study the effects of thapsigargin in the well established organotypic brain co-slice model composed of the basal nucleus of Meynert (nBM), ventral mesencephalon (vMes), dorsal striatum (dStr) and parietal cortex (Ctx). Cholinergic acetyltransferase-positive neurons in the nBM and dStr and dopaminergic tyrosine hydroxylasepositive neurons in the vMes survived, when cultured for 4 weeks with nerve growth factor and glial cell line-derived neurotrophic factor. Nerve fibers of cholinergic nBM neurons grew into the cortex and dopaminergic nerve fibers sprouted into dopamine D2 receptor-positive dStr. The whole co-slice contained a dense laminin-positive capillary network. Treatment of co-cultures with 3 μM thapsigargin for 24 hr significantly decreased the number of cholinergic neurons and dopaminergic neurons. This cell death displayed apoptotic DAPI-positive malformed nuclei and enhanced TUNEL-positive cells. Thapsigargin selectively stimulated the laminin-positive capillary growth between the nBM and Ctx. In conclusion, the induced cell death of cholinergic and dopaminergic neurons may be accompanied by enhanced angiogenic activity.

That promising neuroprotectants failed to demonstrate benefit against stroke highlights the great difficulties to translate preclinical pharmacological effects in clinical outcomes. Part of this hurdle implies the complex response to injury of the neurovascular unit increasing the cerebrovascular permeability at the level of the blood-brain barrier (BBB). Previous studies reported neuroprotection in animal models upon activation of the nuclear receptor PPARα (peroxisome proliferator-activated receptor) α, but the cellular targets at the BBB level remain largely unexplored. Here, to study whether PPAR-α activation acts on BBB permeability, we adapted a mouse BBB cell model to ischaemic conditions at the stage of occlusion defined in vitro as oxygen-glucose deprivation (OGD). This model consists of a co-culture of brain capillary endothelial cells (ECs) on a filter insert placed upon a rat glial cell culture. The EC monolayer permeability increase induced by 4 h of OGD was significantly restricted after treatment with the PPAR-α agonist fenofibric acid (FA) 24 h before or at the onset of OGD. Treatments of separated ECs or glial cells showed that this protective effect was conferred by BBB ECs but not glial cells. Furthermore, co-cultures with ECs from PPAR-α-deficient mice revealed that FA had no effect on OGD-induced hyperpermeability. No transcriptional modulation of classical PPAR-α target genes such as SOD, ICAM-1, VCAM-1, ACO, CPT-1, PDK-4 or ET-1 was observed in wild type mouse ECs. In conclusion, these results suggest that part of the preventive PPAR-α-mediated protection may occur via BBB ECs by limiting hyperpermeability.

Sepsis is a major disease entity with important clinical implications. It is associated with a high mortality rate in humans. Recently, several studies have demonstrated that Intensive Care Unit survivors present long-term cognitive impairment, including alterations in memory, attention, concentration and/or global loss of cognitive function. The pathogenesis of septic encephalopathy and cognitive impairment are still poorly known and further understanding of these processes is necessary for the development of effective preventive and therapeutic interventions. Here we discuss the clinical presentation and underlying pathophysiology of the encephalopathy and neurobiology of the cognitive impairment associated with sepsis.

A new nosologic vascular pattern that is defined by chronic cerebrospinal venous insufficiency (CCSVI) has been strongly associated with multiple sclerosis. The picture is characterized by significant obstacles of the main extracranial cerebrospinal veins, the jugular and the azygous system, and by the opening of substitute circles. The significance of collateral circle is still neglected. To the contrary, substitute circles are alternative pathways or vicarious venous shunts, which permit the drainage and prevent intracranial hypertension. In accordance with the pattern of obstruction, even the intracranial and the intrarachidian veins can also become substitute circles, they permit redirection of the deviated flow, piping the blood towards available venous segments outside the central nervous system. We review the complex gross and radiological anatomy of collateral circulation found activated by the means of EchoColor-Doppler and selective venography in the event of CCSVI, focusing particularly on the suboccipital cavernous sinus (SCS), the condylar venous system, the pterygoid plexus, the thyroid veins, and the emiazygous-lumbar venous anastomosis with the left renal vein.