A non-human primate model of stroke reproducing endovascular thrombectomy and allowing long-term imaging and neurological read-outs.

Stroke is a devastating disease. Endovascular mechanical thrombectomy is dramatically changing the management of acute ischemic stroke, raising new challenges regarding brain outcome and opening up new avenues for brain protection. In this context, relevant experiment models are required for testing new therapies and addressing important questions about infarct progression despite successful recanalization, reversibility of ischemic lesions, blood-brain barrier disruption and reperfusion damage. Here, we developed a minimally invasive non-human primate model of cerebral ischemia (Macaca fascicularis) based on an endovascular transient occlusion and recanalization of the middle cerebral artery (MCA). We evaluated per-occlusion and post-recanalization impairment on PET-MRI, in addition to acute and chronic neuro-functional assessment. Voxel-based analyses between per-occlusion PET-MRI and day-7 MRI showed two different patterns of lesion evolution: "symptomatic salvaged tissue" (SST) and "asymptomatic infarcted tissue" (AIT). Extended SST was present in all cases. AIT, remote from the area at risk, represented 45% of the final lesion. This model also expresses both worsening of fine motor skills and dysexecutive behavior over the chronic post-stroke period, a result in agreement with cortical-subcortical lesions. We thus fully characterized an original translational model of ischemia-reperfusion damage after stroke, with consistent ischemia time, and thrombus retrieval for effective recanalization.

Implementation of French Recommendations for the Prevention and the Treatment of Hospital-acquired Pneumonia: A Cluster-randomized Trial.

BACKGROUND: We determined whether an audit on the adherence to guidelines for hospital-acquired pneumonia (HAP) can improve the outcomes of patients in intensive care units (ICUs). METHODS: This study was conducted at 35 ICUs in 30 hospitals. We included consecutive, adult patients hospitalized in ICUs for 3 days or more. After a 3-month baseline period followed by the dissemination of recommendations, an audit on the compliance to recommendations (audit period) was followed by a 3-month cluster-randomized trial. We randomly assigned ICUs to either receive audit and feedback (intervention group) or participate in a national registry (control group). The primary outcome was the duration of ICU stay. RESULTS: Among 1856 patients enrolled, 602, 669, and 585 were recruited in the baseline, audit, and intervention periods, respectively. The composite measures of compliance were 47% (interquartile range [IQR], 38-56%) in the intervention group and 42% (IQR, 25-53%) in the control group (P = .001). As compared to the baseline period, the ICU lengths of stay were reduced by 3.2 days in the intervention period (P = .07) and by 2.8 days in the control period (P = .02). The durations of ICU stay were 7 days (IQR, 5-14 days) in the control group and 9 days (IQR, 5-20 days) in the intervention group (P = .10). After adjustment for unbalanced baseline characteristics, the hazard ratio for being discharged alive from the ICU in the control group was 1.17 (95% confidence interval, .69-2.01; P = .10). CONCLUSIONS: The publication of French guidelines for HAP was associated with a reduction of the ICU length of stay. However, the realization of an audit to improve their application did not further improve outcomes. CLINICAL TRIALS REGISTRATION: NCT03348579.

PET-MRI nanoparticles imaging of blood-brain barrier damage and modulation after stroke reperfusion.

In an acute ischaemic stroke, understanding the dynamics of blood-brain barrier injury is of particular importance for the prevention of symptomatic haemorrhagic transformation. However, the available techniques assessing blood-brain barrier permeability are not quantitative and are little used in the context of acute reperfusion therapy. Nanoparticles cross the healthy or impaired blood-brain barrier through combined passive and active processes. Imaging and quantifying their transfer rate could better characterize blood-brain barrier damage and refine the delivery of neuroprotective agents. We previously developed an original endovascular stroke model of acute ischaemic stroke treated by mechanical thrombectomy followed by positron emission tomography-magnetic resonance imaging. Cerebral capillary permeability was quantified for two molecule sizes: small clinical gadolinium Gd-DOTA (<1 nm) and AGuIX® nanoparticles (∼5 nm) used for brain theranostics. On dynamic contrast-enhanced magnetic resonance imaging, the baseline transfer constant K trans was 0.94 [0.48, 1.72] and 0.16 [0.08, 0.33] ×10-3 min-1, respectively, in the normal brain parenchyma, consistent with their respective sizes, and 1.90 [1.23, 3.95] and 2.86 [1.39, 4.52] ×10-3 min-1 in choroid plexus, confirming higher permeability than brain parenchyma. At early reperfusion, K trans for both Gd-DOTA and AGuIX® nanoparticles was significantly higher within the ischaemic area compared to the contralateral hemisphere; 2.23 [1.17, 4.13] and 0.82 [0.46, 1.87] ×10-3 min-1 for Gd-DOTA and AGuIX® nanoparticles, respectively. With AGuIX® nanoparticles, K trans also increased within the ischaemic growth areas, suggesting added value for AGuIX®. Finally, K trans was significantly lower in both the lesion and the choroid plexus in a drug-treated group (ciclosporin A, n = 7) compared to placebo (n = 5). K trans quantification with AGuIX® nanoparticles can monitor early blood-brain barrier damage and treatment effect in ischaemic stroke after reperfusion.