A mild and efficient extraction method for polysaccharides from Sinonovacula constricta and study of their structural characteristic and antioxidant activities.

The aim of this paper is to develop a mild and efficient extraction method for polysaccharides from Sinonovacula constricta (SCP) using enzyme extraction, and analyze the structural characteristics and antioxidant activities of the two purified polysaccharide fractions (SCP-1 and SCP-2). Firstly, enzyme extraction conditions were optimized, and the conditions were found to be, as follows: enzymolysis time 173.0 min, pH 8.2, enzymolysis temperature 50.0 ℃ and enzyme content 4.0%. Comparison between enzymatic extraction and water extraction was obtained from visual, UV-visible and IR spectrum images. The results clearly indicate that there is no significant difference between them with regard to the composition of the SCP fraction, but the polysaccharide content produced by enzymatic extraction is higher. Then, the physicochemical properties and structural characteristics of SCP-1 and SCP-2 were investigated using FT-TR, UV, GC and HPGPC. The carbohydrate content, sulfuric radicals and uronic acids of the two fractions were detected. Both SCP-1 and SCP-2 were mainly consisted of glucose, but their molecular weights were different. In addition, compared the Fe2+ chelating activity, ABTS+ radical and superoxide radical scavenging activity, and lipid peroxidation inhibition activity of SCP-1 and SCP-2, it turned out that SCP-2 had stronger antioxidant activity than SCP-1.

Late recanalisation beyond 24 hours is associated with worse outcome: an observational study.

OBJECTIVES: We evaluated the rate of late recanalisation beyond 24 h after intravenous thrombolysis (IVT) and its relationship with haemorrhagic transformation and outcome. METHODS: We reviewed prospectively collected clinical and imaging data from acute ischaemic stroke patients with distal internal carotid artery or proximal middle cerebral artery occlusion who underwent angiography on admission, 24 h and 1 week after IVT. Patients were trichotomised according to vascular status: timely recanalisation (<24 h), late recanalisation (24 h-7 days), and no recanalisation. RESULTS: Non-invasive angiography revealed timely recanalisation in 52 (50.0 %) patients, late recanalisation in 25 (24.0 %) patients, and no recanalisation in 27 (26.0 %) patients. Pre-existing atrial fibrillation was associated with the occurrence of late recanalisation (odds ratio 6.674; 95 % CI: 1.197 to 37.209; p = 0.030). In patients without timely recanalisation, shift analysis indicated that late recanalisation led to a worse modified Rankin Scale score (odds ratio 6.787; 95 % CI: 2.094 to 21.978; p = 0.001). CONCLUSIONS: About half of all patients without recanalisation by 24 h after IVT may develop late recanalisation within 1 week, along with higher mRS scores by 3 months. Pre-existing atrial fibrillation is an independent predictor for late recanalisation. KEY POINTS: • About half of patients may develop late recanalisation within 1 week. • Pre-existing atrial fibrillation was associated with the occurrence of late recanalisation. • Late recanalisation led to a higher mRS score than no recanalisation.

Defining Core and Penumbra in Ischemic Stroke: A Voxel- and Volume-Based Analysis of Whole Brain CT Perfusion.

Whole brain computed tomography perfusion (CTP) has the potential to select eligible patients for reperfusion therapy. We aimed to find the optimal thresholds on baseline CTP for ischemic core and penumbra in acute ischemic stroke. We reviewed patients with acute ischemic stroke in the anterior circulation, who underwent baseline whole brain CTP, followed by intravenous thrombolysis and perfusion imaging at 24 hours. Patients were divided into those with major reperfusion (to define the ischemic core) and minimal reperfusion (to define the extent of penumbra). Receiver operating characteristic (ROC) analysis and volumetric consistency analysis were performed separately to determine the optimal threshold by Youden's Index and mean magnitude of volume difference, respectively. From a series of 103 patients, 22 patients with minimal-reperfusion and 47 with major reperfusion were included. Analysis revealed delay time ≥ 3 s most accurately defined penumbra (AUC = 0.813; 95% CI, 0.812-0.814, mean magnitude of volume difference = 29.1 ml). The optimal threshold for ischemic core was rCBF ≤ 30% within delay time ≥ 3 s (AUC = 0.758; 95% CI, 0.757-0.760, mean magnitude of volume difference = 10.8 ml). In conclusion, delay time ≥ 3 s and rCBF ≤ 30% within delay time ≥ 3 s are the optimal thresholds for penumbra and core, respectively. These results may allow the application of the mismatch on CTP to reperfusion therapy.