Purpose: To investigate the brain iron deposits in patients with Alzheimer's disease (AD) and healthy age-matched controls using phase imaging. Materials and Methods:Twenty-six AD patients and 24 healthy controls were recruited. A three-dimensional highresolution, gradient-echo sequence was used to acquire phase data in the coronal plane. A high-pass filter was used to remove the phase variation caused by field inhomogeneity. The regions evaluated included the bilateral putamen, globus pallidus, and the head and body of the hippocampus.Results: Significantly lower phase values in both the basal ganglion and hippocampus were revealed in the AD group compared to the normal controls (P Ͻ 0.05). The phase value in the right side of the head of the hippocampus had a moderate positive correlation with the MMSE score (rϭ 0.603, P ϭ 0.000) and a negative correlation with the duration of the disease (r ϭ Ϫ0.677, P ϭ 0.013). Using Ϫ0.0972 radians as an optimal cutoff value, the sensitivity and specificity for differentiation between AD and normal controls reached 95.8 and 80.8%, respectively. Conclusion:Phase imaging proved to be a useful method for the differentiation between normal controls and AD patients. An investigation of the excessive accumulation of iron in the hippocampus may help us better understand the pathologic process and neuropsychological dysfunction of AD disease.

Background and Purpose-The intraluminal suture technique for producing middle cerebral artery occlusion in rodents is the most commonly used method for modeling focal cerebral ischemia associated with clinical ischemic stroke. Synchrotron radiation angiography may provide a novel solution to directly monitor the success of middle cerebral artery occlusion. Methods-Twenty adult Sprague-Dawley rats for middle cerebral artery occlusion models were prepared randomly with different suture head silicone coating. In vivo imaging was performed at beam line BL13W1, Shanghai Synchrotron Radiation Facility, Shanghai, China. Results-Silicone-coated suture was superior to uncoated suture for producing consistent brain infarction. Additionally, silicone coating length was an important variable controlling the extent of the ischemic lesion: infarcts affected predominantly the caudate-putamen with large variability (Ͻ2 mm), both the cortex and caudate-putamen (2-3.3 mm), and most of the hemisphere, including the hypothalamus (Ͼ3.3 mm). Conclusions-Synchrotron radiation angiography provides a useful tool to observe hemodynamic changes after middle cerebral artery occlusion, and the physical properties of suture are critical to the success of the middle cerebral artery occlusion model. (Stroke. 2012;43:888-891.)Key Words: angiography Ⅲ middle cerebral artery occlusion Ⅲ synchrotron radiation T he focal cerebral ischemia model involves the occlusion of the middle cerebral artery (MCAO) and typically results in localized brain infarction, which recapitulates many of the pathophysiological and histopathologic features of stroke. The most common technique for MCAO is the intraluminal filament model. 1 However, 1 limitation of the suture model is its high variability in infarct size. 2 Factors that contribute to such variation include differences in animal strain and weight, method of anesthesia, blood pressure, brain and body temperature, brain vascular anatomy, suture material, duration, and site of occlusion. Physical properties of the filament are important because it is the key factor that affects lesion volume 3 ; however, there is no direct evidence to confirm this principle. 4,5 Regional cerebral blood flow can be measured using autoradiography and laser Doppler flowmetry to confirm successful MCAO, but neither method can dynamically monitor changes of cerebral blood flow in deeper tissue during ischemia-reperfusion. 6,7 Synchrotron radiation angiography (SRA) may represent a novel solution to directly and dynamically monitor MCAO. 8 In the present study, we used SRA to examine if the coating length was critical for producing a highly reproducible stroke model. Materials and Methods Experimental GroupsAnimal procedures were approved by the Institutional Animal Care and Use Committee of Shanghai Jiao Tong University, Shanghai, China. Twenty male Sprague-Dawley rats (SLAC, Shanghai, China) weighing 270 to 350 g were divided into 4 groups randomly (nϭ5/group). The sutures with different physical properties were used in 4 groups t...

The purpose of the study was to evaluate the feasibility of microbubbles as phase contrast imaging (PCI) agents for angiography applications. The hypothesis was that the introduction of microbubbles into tissue produces a significant change in the refractive index and highlights the lumen of the vessel in PCI. The absorption and phase contrast images of commercially available microbubbles were obtained and compared in vitro. A further increase in contrast was observed in PCI. Microbubbles highlighted the lumen of the renal microvessels, acting as a positive contrast medium in ex vivo imaging. In addition, home-made microbubbles with larger diameters were introduced for image contrast enhancement in living tumor-bearing mice, demonstrating the feasibility of microbubble-based x-ray phase-contrast imaging for tumor vasculature in vivo.

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The suture middle cerebral artery occlusion (MCAO) model is used worldwide in both academia and industry. However, the variable occurrence of dysplasia in posterior communicating arteries (PcomAs) induces high mortality and instability in permanent MCAO models, limiting the model's application to transient focal ischemia. In particular, high mortality in intraluminal suture MCAO models is associated with the dysplasia of PcomAs in C57BL/6 mice. Optimization of silicone coating length is critical for reducing mortality and generating stable infarct in this model. The aim of our study is to reduce mortality and improve the reproducibility of the intraluminal suture MCAO model in C57BL/6 mice, which have high variation in PcomA dysplasia. Adult male C57BL/6 mice (n=38) underwent MCAO using sutures with various diameters and silicone coating lengths. The occlusion of cerebral vessels was examined by synchrotron radiation live angiography. The morphology of PcomAs was examined under a microscope after MICROFIL(®) infusion. Neurological outcome, infarct volume, and mortality were examined within 28 days. Optimizing the silicone coating on an 8-0 suture tip, we were able to reduce the model mortality to zero after permanent occlusion in C57BL/6 and produce stable brain infarct volume independent of the patency of PcomAs.

Transient middle cerebral artery occlusion (tMCAO) model is widely used to mimic human focal ischemic stroke in order to study ischemia/reperfusion brain injury in rodents. In tMCAO model, intraluminal suture technique is widely used to achieve ischemia and reperfusion. However, variation of infarct volume in this model often requires large sample size, which hinders the progress of preclinical research. Our previous study demonstrated that infarct volume was related to the success of reperfusion although the reason remained unclear. The aim of present study is to explore the relationship between focal thrombus formation and model reproducibility with respect to infarct volume. We hypothesize that suture-induced thrombosis causes infarct volume variability due to insufficient reperfusion after suture withdrawal. Seventy-two adult male CD-1 mice underwent 90 minutes of tMCAO with or without intraperitoneal administration of heparin. Dynamic synchrotron radiation microangiography (SRA) and laser speckle contrast imaging (LSCI) were performed before and after tMCAO to observe the cerebral vascular morphology and to measure the cerebral blood flow in vivo. Infarct volume and neurological score were examined to evaluate severity of ischemic brain injury. We found that the rate of successful reperfusion was much higher in heparin-treated mice compared to that in heparin-free mice according to the result of SRA and LSCI at 1 and 3 hours after suture withdrawal (p<0.05). Pathological features and SRA revealed that thrombus formed in the internal carotid artery, middle cerebral artery or anterior cerebral artery, which blocked reperfusion following tMCAO. LSCI showed that cortical collateral circulation could be disturbed by thrombi. Our results demonstrated that suture-induced thrombosis was a critical element, which affects the success of reperfusion. Appropriate heparin management provides a useful approach for improving reproducibility of reperfusion model in mice.

The microbial communities in freshwater have raised concerns about the ecosystem and human health. Many ecological environmental problems have been found in urban river because of the unreasonable use and long-term wastewater discharge. In this study, we explored the bacterial community composition, abundance of 14 antibiotics and 21 antibiotic resistance genes (ARGs), and water environment features in seven water samples and seven sediment samples from Ba River in Xi’an, China. Results showed Proteobacteria and Bacteroidetes were the dominant phyla in all samples, and sediment samples had a higher bacterial diversity and richness than it in water. Bacterial communities of site 5 and 6 were clustered in discrepant patterns compared to those at remaining sites from other samples. It might be influenced by nutrients, heavy metals and antibiotics. Antibiotics concentrations ranged from 1.26 to 1.61 × 103 ng L-1 in water samples and 1.55 to 4.05 × 102 μg kg-1 in sediment samples. Sulfamerazine (SM1) and erythromycin (ERY) were the chief antibiotics in water samples, while the level of oxytetracycline (OTC) and cefazolin (CFZ) were higher in sediment samples. Canonical correspondence analysis showed that trimethoprim (TMP) was significantly related to Acinetobacter in W6, and that SM1 and OTC had positive correlation with Arcobacter in W5. The tetC, blaTEM, ermF and sul1 had higher pollution abundance ranging from 10-4 to 100 copies/16S rRNA gene copies in all samples. Significant correlations were observed between ARGs and matching antibiotics, suggesting that antibiotics can pose the selective pressure on ARGs in this river. In summary, these finding might provide some new data to the limited information available on the bacterial community characteristics, abundance of antibiotics and ARGs in urban river of China.

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