Midlife cognitive decline is now recognized as a factor of poor prognosis for late-life dementia. Although an epidemiological link has been suggested with high fat diet (HFD)-induced metabolic ...disorders, the effect of a long period of HFD on midlife cerebrovascular and cognitive functions remains unproven. A cohort of 216 young mice was fed with HFD up to middle age (12 months), and kinetically characterized for metabolic status, including weight, blood lipid profile, hepatic fat accumulation, glucose intolerance, and visceral adiposity. Metabolic disorders were evidenced from 3 months of HFD. Visual recognition memory and flexibility were significantly altered and associated to a visceral adiposity whereas spatial reference memory and working memory did not. Concomitantly, a progressive dysfunction of the vascular endothelium-dependent relaxation was detected in both middle cerebral artery and parenchymal arterioles, with consequences on the regulation of cerebral blood flow, but without any modification of the basal brain tissue MRI perfusion signal. Our data collection empowered us to stratify the mice according to their heterogeneous response to diet, and to propose a statistical prediction model for cognitive impairment, combining visceral adiposity and cerebral vasomotion in a diagnostic perspective of early neurological deficits.
Cerebral microbleeds: Beyond the macroscope Pétrault, Maud; Casolla, Barbara; Ouk, Thavarak ...
International Journal of Stroke,
07/2019, Letnik:
14, Številka:
5
Book Review, Journal Article
Recenzirano
While being increasingly recognized in clinical routine, brain microbleeds remain a puzzling finding for physicians. These small dot-like lesions are thought to be old perivascular collections of ...hemosiderin deposits. They can be found in different neurological settings such as cerebrovascular or neurodegenerative diseases. While their microscopic size would suggest considering these lesions as anecdotal, they are now regarded as biomarkers of severity of an underlying cerebrovascular disease. Their natural history and the interactions with surrounding brain cells remain unknown. However, their presence may impact therapeutic decisions. Deciphering the biological mechanisms leading to, or following microbleeds would enable us to address a key question: do microbleeds arise and impact the surrounding parenchyma like a miniature version of intracerebral hemorrhages or do they represent a different kind of injury? We hereby discuss, based on both clinical and experimental literature, the gap between the definition of microbleeds coming from neuroimaging and the pathophysiological hypotheses raised from histopathological and experimental data. Our analysis supports the need for a convergent effort from clinicians and basic scientists to go beyond the current “macro” view and disclose the cellular and molecular insights of these cerebral hemorrhagic microlesions.
Background: The origin of pre-existing cognitive impairment in stroke patients remains controversial, with a vascular or a degenerative hypothesis. Objective: To determine whether endothelial ...dysfunction is associated with pre-existing cognitive problems, lesion load and biological anomalies in stroke patients. Methods: Patients originated from the prospective STROKDEM study. The baseline cognitive state, assessed using the IQ-CODE, and risk factors for stroke were recorded at inclusion. Patients with an IQ-CODE score >64 were excluded. Endothelial function was determined 72 h after stroke symptom onset by non-invasive digital measurement of endothelium-dependent flow-mediated dilation and calculation of the reactive hyperemia index (RHI). RHI ≤ 1.67 indicated endothelial dysfunction. Different biomarkers of endothelial dysfunction were analysed in blood or plasma. All patients underwent MRI 72 h after stroke symptom onset. Results: A total of 86 patients were included (52 males; mean age 63.5 ± 11.5 years). Patients with abnormal RHI have hypertension or antihypertensive treatment more often. The baseline IQ-CODE was abnormal in 33 (38.4%) patients, indicating a pre-existing cognitive problem. Baseline IQ-CODE > 48 was observed in 15 patients (28.3%) with normal RHI and in 18 patients (54.6%) with abnormal RHI (p = 0.016). The RHI median was significantly lower in patients with abnormal IQ-CODE. Abnormal RHI was associated with a significantly higher median FAZEKAS score (2.5 vs. 2; p = 0.008), a significantly higher frequency of periventricular lesions (p = 0.015), more white matter lesions (p = 0.007) and a significantly higher cerebral atrophy score (p < 0.001) on MRI. Vascular biomarkers significantly associated with abnormal RHI were MCP-1 (p = 0.009), MIP_1a (p = 0.042), and homocysteinemia (p < 0.05). Conclusions: A vascular mechanism may be responsible for cognitive problems pre-existing stroke. The measurement of endothelial dysfunction after stroke could become an important element of follow-up, providing an indication of the functional and cognitive prognosis of stroke patients.
Persistent pulmonary hypertension of the newborn (PPHN) causes significant morbidity and mortality in neonates.
-3 Poly-unsaturated fatty acids have vasodilatory properties in the perinatal lung. We ...studied the circulatory effects of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in fetal sheep and in fetal pulmonary arterial rings.
At 128 days of gestation, catheters were placed surgically in fetal systemic and pulmonary circulation, and a Doppler probe around the left pulmonary artery (LPA). Pulmonary arterial pressure and LPA flow were measured while infusing EPA or DHA for 120 min to the fetus, to compute pulmonary vascular resistance (PVR). The dose effects of EPA or DHA were studied in vascular rings pre-constricted with serotonin. Rings treated with EPA were separated into three groups: E+ (intact endothelium), E- (endothelium stripped) and LNA E+ (pretreatment of E+ rings with l-nitro-arginine).
EPA, but not DHA, induced a significant and prolonged 25% drop in PVR (
= 8,
< 0.001). Incubation of vascular rings with EPA (100 µM) caused a maximum relaxation of 60% in the E+ (
= 6), whereas vessel tone did not change in the E- (
= 6,
< 0.001). The vascular effects of EPA were significantly decreased in LNA E+ (
= 6). Incubation with DHA resulted in only a mild relaxation at the highest concentration of DHA (300 µM) compared to E+.
EPA induces a sustained pulmonary vasodilatation in fetal lambs. This effect is endothelium- and dose-dependent and involves nitric oxide (NO) production. We speculate that EPA supplementation may improve pulmonary circulation in clinical conditions with PPHN.
Stroke is one of the major causes of mortality and disability in adults in industrialized countries. Despite numerous preclinical studies and clinical trials in the field of cerebral ischemia, no ...pharmacological agent has been validated in the treatment of acute ischemic, except thrombolysis. Cerebral ischemia is not only a neuronal disease but it affects the entire neurovascular unit. The therapeutic strategy in stroke should be more global and combine preventive approaches, acute phase treatment and long-term care to improve recovery and prevent or treat affective and cognitive post-stroke consequences. There is an imperative need to develop disease-modifying drugs, which should be able to induce neuroprotection, to serve as adjuvants for thrombolysis by decreasing the hemorrhagic risk and to limit the long-term post-stroke consequences. This review presents the potential effects of Peroxisome Proliferator-Activated Receptors (PPARs) and of their agonists in stroke. We focus on each PPAR receptor and detail their implication in stroke. PPARs are nuclear receptors, acting as ligand-dependent transcription factors. They are expressed in the neurovascular unit that suggests that PPARs could play a role in stroke. Indeed, it has been shown that they are able to interfere with pathways implicated in the pathophysiology of stroke. They could be an answer to this disease-modifying drug concept, being able to act on the different phases of ischemia.
The impact of fenofibrate, a peroxisome proliferator-activated receptor-alpha (PPAR-α) agonist, on the risk of thrombolysis-induced hemorrhage during the acute phase of stroke in a rat model of ...stroke was studied. One-hour middle cerebral artery occlusion followed by thrombolysis with tissue plasminogen activator was made in rats receiving either fenofibrate or vehicle for 72 h after stroke. Evaluation of infarct, hemorrhage, middle cerebral artery vasoreactivity, and immunochemistry (CD11b for microglial activation, myeloperoxidase, and ICAM-1 for neutrophil infiltration) was performed. The PPAR-alpha agonist significantly reduced the risk of hemorrhage after thrombolysis in parallel with a decrease in the infarct volume and in the stroke-induced vascular endothelial dysfunction. These effects are concomitant with a reduction in microglial activation and neutrophil infiltration in infarct area. Our results strengthen the idea that using drugs such as fenofibrate, with pleiotropic properties due to PPAR-alpha agonism, may be of value to reduce thrombolysis-induced hemorrhage during acute stroke.
We investigated the involvement of potassium inward rectifier current (Kir) impairment in smooth muscle cells of cerebral arteries under the condition of increased susceptibility of stroke, in ...spontaneously hypertensive stroke-prone (SHRsp) rats compared to spontaneously hypertensive (SHR) ones as well as to controls (WKY). Kir current was studied with whole-cell patch-clamp techniques on freshly isolated single smooth muscle cells (SMC) of middle cerebral artery (MCA) from SHRsp, SHR, and WKY male rats (are range 12–32 weeks). A significant and progressive Kir current density reduction was observed on SMC of SHRsp rats from the 22nd week of age on, as opposed to the Kir current density stability observed over the same time in the SMC of WKY and SHR rats. The Kir density alteration was correlated to the age of the SHRsp animals. These results suggest that in the cerebral vascular smooth muscle cells of SHRsp rats, there is a progressive Kir channel impairment, leading to a reduction of Kir current density. This impairment may underpin a lack of vasodilation of the MCA and be implicated in the stroke-proneness observed on SHRsp animals.
The risk of intracerebral hemorrhage still greatly limits the use of tPA in stroke patients. Research is ongoing in order to identify the pathophysiological mechanisms at play, detect predictive ...biomarkers and discover new pharmacological targets to develop preventive or curative treatments. Going through experimental and clinical studies, this review focuses on the role of neutrophils as key predictive biomarkers for thrombolysis-induced hemorrhages and as pharmacological targets to limit their occurrence. To date, there are no established pharmacological modulators of neutrophils for ischemic stroke and its hemorrhagic complications. Several strategies are under evaluation, including lipid-lowering drugs, free radical scavengers, or minocycline, as well as non-pharmacological interventions such as physical exercise.
Even with optimal dopaminergic treatments, many patients with Parkinson's disease (PD) are frequently incapacitated by apathy prior to the development of dementia. We sought to establish whether ...rivastigmine's ability to inhibit acetyl- and butyrylcholinesterases could relieve the symptoms of apathy in dementia-free, non-depressed patients with advanced PD.
We performed a multicentre, parallel, double-blind, placebo-controlled, randomised clinical trial (Protocol ID: 2008-002578-36; clinicaltrials.gov reference: NCT00767091) in patients with PD with moderate to severe apathy (despite optimised dopaminergic treatment) and without dementia. Patients from five French university hospitals were randomly assigned 1:1 to rivastigmine (transdermal patch of 9.5 mg/day) or placebo for 6 months. The primary efficacy criterion was the change over time in the Lille Apathy Rating Scale (LARS) score.
101 consecutive patients were screened, 31 were eligible and 16 and 14 participants were randomised into the rivastigmine and placebo groups, respectively. Compared with placebo, rivastigmine improved the LARS score (from -11.5 (-15/-7) at baseline to -20 (-25/-12) after treatment; F(1, 25)=5.2; p=0.031; adjusted size effect: -0.9). Rivastigmine also improved the caregiver burden and instrumental activities of daily living but failed to improve quality of life. No severe adverse events occurred in the rivastigmine group.
Rivastigmine may represent a new therapeutic option for moderate to severe apathy in advanced PD patients with optimised dopaminergic treatment and without depression dementia. These findings require confirmation in a larger clinical trial. Our results also confirmed that the presence of apathy can herald a pre-dementia state in PD.
Clinicaltrials.gov reference: NCT00767091.
This study aims at determining the ability of clinical-based doses of four oral anticoagulants to transform the onset of a cerebral microhemorrhages (CMH) burden into a symptomatic intracerebral ...hemorrhage (ICH) in the healthy brain, and precipitate cognitive impairment. Wild-type mice were anticoagulated for 10 days using apixaban, rivaroxaban or dabigatran as direct oral anticoagulants (DOACs), or warfarin as vitamin K-antagonist. Meanwhile, a burden of ∼20 CMHs was induced in the Sylvian territory by intra-carotid injection of cyclodextrin nanoparticles. At bleeding onset, only warfarin provoked deadly hematoma, and dramatically increased mortality (+45%). All the DOACs enhanced CMH burden through a greater number of intermediate-sized microhemorrhages (+80% to +180%). Although silent at onset, both baseline- and anticoagulant-enhanced CMH burdens increased mortality (+11% to +58%) along the following year without statistical difference among groups, and despite cessation of anticoagulation and absence of CMH progression or transformation into ICH. All survivor mice exhibited reduction in visual recognition memory from 9 months. In the healthy brain, DOACs preserve the onset of microhemorrhages from transformation into ICH, and do not precipitate cognitive impairment despite enhancement of CMH burden. High CMH burdens should however be considered for early detection and preventive memory care apart from anticoagulation decisions.
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•Oral anticoagulants enhance the cerebral microhemorrhage burden.•Only warfarin transforms cerebral microhemorrhages into deadly hematoma.•Disseminated cerebral microhemorrhages induce cognitive impairment in healthy mice.•Oral anticoagulant-enhanced microhemorrhages do not precipitate cognitive impairment.
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