Therapeutic imaging window of cerebral infarction revealed by multisequence magnetic resonance imaging An animal and clinical study

In this study, we established a Wistar rat model of right middle cerebral artery occlusion and observed pathological imaging changes （T2-weighted imaging [T2WI], T2FLAIR, and diffusion-weighted imaging [DWI]） following cerebral infarction. The pathological changes were divided into three phases： early cerebral infarction, middle cerebral infarction, and late cerebral infarction. In the early cerebral infarction phase （less than 2 hours post-infarction）, there was evidence of intracellular edema, which improved after reperfusion. This improvement was defined as the ischemic penumbra. In this phase, a high DWI signal and a low apparent diffusion coefficient were observed in the right basal ganglia region. By contrast, there were no abnormal T2WI and T2FLAIR signals. For the middle cerebral infarction phase （2-4 hours post-infarction）, a mixed edema was observed. After reperfusion, there was a mild improvement in cell edema, while the angioedema became more serious. A high DWI signal and a low apparent diffusion coefficient signal were observed, and some rats showed high T2WI and T2FLAIR signals. For the late cerebral infarction phase （4-6 hours post-infarction）, significant angioedema was visible in the infarction site. After reperfusion, there was a significant increase in angioedema, while there was evidence of hemorrhage and necrosis. A mixed signal was observed on DWI, while a high apparent diffusion coefficient signal, a high T2WI signal, and a high T2FLAIR signal were also observed. All 86 cerebral infarction patients were subjected to T2WI, T2FLAIR, and DWI. MRI results of clinic data similar to the early infarction phase of animal experiments were found in 51 patients, for which 10 patients （10/51） had an onset time greater than 6 hours. A total of 35 patients had MRI results similar to the middle and late infarction phase of animal experiments, of which eight patients （8/35） had an onset time less than 6 hours. These data suggest that defining the ＂therapeutic time window＂ as the time 6 hours after infarction may not be suitable for all patients. Integrated application of MRI sequences including T2WI, T2FLAIR, DW-MRI, and apparent diffusion coefficient mapping should be used to examine the ischemic penumbra, which may provide valuable information for identifying the ＂therapeutic time window＂.

Light controlled imaging probes for intracellular target recognition： photochromism as a tool to enhance sensing precision

Chemosensors and imaging probes have been the focus of significant research interest over the past few decades. In part due to ease of preparation and simplicity in manipulation, fluorescent probes have been extensively used for biomedical applications. When used for #7 vitro cell imaging [1,2],

In situ self-assembly of near-infrared-emitting gold nanoparticles into body-clearable ID nanostructures with rapid lysosome escape and fast cellular excretion

The integration of strong near-infrared(NIR)emission,rapid lysosome escape,fast cellular excretion,and efficient total body clearance is highly desired for nanoparticles(NPs)to achieve synergistic functions in both molecular imaging and delivery.Herein,using a well-designed cyclopeptide(CP)that can spontaneously assem ble into controllable nanofibers a s template,a facile strategy is reported for in situ self-assembly of NIR-emitting gold NPs(AuNPs)into ordered and well-controlled one-dimensional(1D)nanostructures(AuNPs@CP)with greatly enhanced NIR emission(〜6 fold).Comparing with the unassem bled AuNPs,the AuNPs@CP are observed to enter living cells through endocytosis,escap e from lysosome rapidly,and excrete the cell fast,which shows high gene transfection efficiencies in construction of cell line with-7.5-fold overexpression of p53 protein.Furthermore,the AuNPs@CP exhibit high in vivo diffusibility and total body clearance efficiency with minimized healthy organ retention,which are also demonstrated to be good nanovectors for plasmid complementary deoxyribonucleic acid 3.1(pcDNA3.1)(+)-internal ribosome entry site(IRES)-green fluorescent protein(GFP)-p53 plasmid with efficient p53 gene over-expression in tumor site.This facile in situ strategy in fabricating highly luminescent 1D nanostructures provides a promising approach toward future translatable multifunctional nanostructures for delivering,tracking,and therapy.