In vivo USPIO-enhanced MR signal characteristics of secondary degeneration in the ipsilateral substantia nigra after middle cerebral artery occlusion at 3T.

BACKGROUND AND PURPOSE: Ultrasmall superparamagnetic iron oxide (USPIO) particles to enhance MRI have been used to study neuroinflammation in vivo. Our purpose was to observe the USPIO-enhanced MR signal alterations in the primary ischemic lesion and ipsilateral substantia nigra after middle cerebral artery occlusion (MCAO) to verify the subsequent sequelae of neuroinflammation seen in the primary ischemic focus and secondary degeneration region. MATERIALS AND METHODS: Sprague-Dawley rats were subjected to transient MCAO. In addition to conventional T2-, T1-weighted imaging, USPIO-enhanced MRI was performed in USPIO-injected stroke rats, while Gd-enhanced imaging was acquired in control stroke rats, on days 3, 6 using a 3-T MR scanner. The MR signal characteristics in the primary ischemic striatum, ipsilateral substantia nigra were noted, compared on histopathological H&E, Prussian blue (PB) staining. RESULTS: After MCAO, USPIO-induced T2 hypointensity changes were observed in the primary ischemic region with BBB impairment at both time points. In the substantia nigra ipsilateral to the primary ischemic lesion, there was no evidence of USPIO accumulation detected by MRI and PB staining, and no BBB leakage reflected by Gd-enhanced imaging on days 3 and 6. CONCLUSION: USPIO-enhanced MR signals have variable characteristics in both primary and remote sites after focal cerebral ischemia. This suggests that the neuroinflammatory response to brain ischemia in the primary ischemic focus and secondary degeneration region have different temporal patterns and pathophysiological mechanisms.

Detection of brain lesions at the skull base using diffusion-weighted imaging with readout-segmented echo-planar imaging and generalized autocalibrating partially parallel acquisitions.

OBJECTIVE: To analyze the value of readout-segmented echo-planar imaging (rs-EPI) with parallel imaging and a two-dimensional (2D) navigator-based reacquisition technique in the detection of brain lesions at the skull base. MATERIALS AND METHODS: A total of 54 patients (male 37, female 17) with suspected skull-base intracranial lesions underwent magnetic resonance imaging (MRI), including pre-T1 weighted imaging, T2-weighted imaging, Fluid Attenuated Inversion Recovery (FLAIR), standard single shot echo-planar imaging diffusion weighted imaging (ss-EPI DWI) and rs-EPI DWI, post-contrast T1-weighted. The total number of lesions and the number of lesions at different sites on all MRI sequences were used as reference measures. Then differences in detecting lesions and image quality between standard ss-EPI DWI and rs-EPI DWI were analyzed. RESULTS: There was a significant difference in the total number of lesions detected by rs-EPI DWI and standard ss-EPI DWI (P = 0.01). But this difference was mainly due to an improved ability of rs-EPI DWI to detect lesions located in the anterior cranial fossa, compared to ss-EPI DWI (P=0.02); the ability of ss-EPI and rs-EPI DWI to detect lesions in the middle cranial fossa and posterior cranial fossa was not significantly different (P = 0.471, P = 0.486, respectively). For image quality, rs-EPI images were significantly better than standard ss-EPI DWI images (P<0.001). CONCLUSION: The rs-EPI DWI technique is a useful tool for the detection and evaluation of lesions located at the skull base.

[Effect of organs biomass by drought stress on the leaf growing stage of Angelica dahurica var. formosana].

OBJECTIVE: To study the effect of natural drought stress conditions on Angelica dahurica var. formnosana vegetative organs biomass accumulation and allocation in leaf growing season. To discuss the changing law of Angelica dahurica var. formosana vegetative organs biomass in different drought stress conditions. METHODS: Measured Angelica dahurica var. formnosana leaf and leafstalk's biomass, all aboveground biomass and the ratio of root biomass, leaf biomass, root/shoot ratio etc. in the growing season under the natural drought stress condition. RESULTS: Slight drought stress condition was good for organs' biomass accumulation, medium and serious drought stress conditions were bad for organs biomass accumulation. Slight and medium drought stress conditions were good for biomass transit to the root in the leaf growing season and serious drought stress condition was not good for that. CONCLUSION: Suitable drought stress can improve the root biomass ratio in Angelica dahurica var. formosana leaf growing season and get a better yield.

Changes in DTI parameters in the optic tracts of macaque monkeys with monocular blindness.

For humans and non-human primates, the alteration of the visual pathway's white matter fibers after visual deprivation has been partially explored. However, the changes in the optic tracts after the transection of the optic nerve have not been well characterized. In the current study, we attempted to investigate the differences in optic tracts between normal and unilateral optic nerve transected macaque monkeys using diffusion tensor imaging (DTI). Four healthy neonatal macaque monkeys were randomly divided into 2 groups, with 2 in each group. Group A served as a control group, and Group B underwent unilateral (right eye) optic nerve transection to produce monocular blindness. Sixteen months (Group B16M) and thirty-two months (Group B32M) after optic nerve transection, diffusion tensor imaging was performed on all monkeys. Then, we compared fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD) and radial diffusivity (RD) in bilateral optic tracts between Group A and Group B and between Group B16M and Group B32M. In both Group B16M and Group B32M, when compared with normal monkeys in Group A, FA was decreased and MD, AD and RD were increased in the bilateral optic tracts of monkeys with monocular blindness. Furthermore, compared with Group B16M, FA was reduced and MD, AD, RD were more obviously increased in the bilateral optic tracts of Group B32M, and noticeable differences in MD, AD and RD were found between the left and right optic tracts in group B32M. We believe that the results of this study would be helpful in investigation of the histological abnormalities of the integrity damage, axonal degeneration and demyelination of optic tracts in macaque monkeys with monocular blindness by DTI parameters in noninvasively and quantitatively.

Noninvasive scoring system for significant inflammation related to chronic hepatitis B.

Although a liver stiffness measurement-based model can precisely predict significant intrahepatic inflammation, transient elastography is not commonly available in a primary care center. Additionally, high body mass index and bilirubinemia have notable effects on the accuracy of transient elastography. The present study aimed to create a noninvasive scoring system for the prediction of intrahepatic inflammatory activity related to chronic hepatitis B, without the aid of transient elastography. A total of 396 patients with chronic hepatitis B were enrolled in the present study. Liver biopsies were performed, liver histology was scored using the Scheuer scoring system, and serum markers and liver function were investigated. Inflammatory activity scoring models were constructed for both hepatitis B envelope antigen (+) and hepatitis B envelope antigen (-) patients. The sensitivity, specificity, positive predictive value, negative predictive value, and area under the curve were 86.00%, 84.80%, 62.32%, 95.39%, and 0.9219, respectively, in the hepatitis B envelope antigen (+) group and 91.89%, 89.86%, 70.83%, 97.64%, and 0.9691, respectively, in the hepatitis B envelope antigen (-) group. Significant inflammation related to chronic hepatitis B can be predicted with satisfactory accuracy by using our logistic regression-based scoring system.

MicroRNA-17~92 inhibits colorectal cancer progression by targeting angiogenesis.

The miR-17~92 microRNA (miRNA) cluster host gene is upregulated in a broad spectrum of human cancers including colorectal cancer (CRC). Previous studies have shown that miR-17~92 promotes tumorigenesis and cancer angiogenesis in some tumor models. However, its role in the initiation and progression of CRC remains unknown. In this study, we found that transgenic mice overexpressing miR-17~92 specifically in epithelial cells of the small and large intestines exhibited decreased tumor size and tumor angiogenesis in azoxymethane and dextran sulfate sodium salt (AOM-DSS)-induced CRC model as compared to their littermates control. Further study showed that miR-17~92 inhibited the progression of CRC via suppressing tumor angiogenesis through targeting multiple tumor angiogenesis-inducing genes, TGFBR2, HIF1α, and VEGFA in vivo and in vitro. Collectively, we demonstrated that miR-17~92 suppressed tumor progression by inhibiting tumor angiogenesis in a genetically engineered mouse model, indicating the presence of cellular context-dependent pro- and anti-cancer effects of miR-17~92.

[The expression and significance of Notch1 in the human kidney tubular cell transdifferentiation induced by TGF-ß(1);].

AIM: To explore the dynamic expression and significance of Notch1 in the human kidney tubular epithelial cell transdifferentiation (KTECT)induced by TGF-ß(1);. METHODS: Normal human kidney epithelial cell line (HK-2) was cultured and then divided into blank group, and TGF-ß(1);(10 ng/mL) induced group. At the 12 h, 24 h, 48 h and 72 h, the morphologic changes of HK-2 cells were observed under an inverted phase contrast microscope. The expression of α-SMA, E-cadherin and Notchl as well as their mRNA were examined by immunohisto-chemistry staining and RT-PCR respictively. RESULTS: Compared with the normal control group, the expression levels ofα-SMA and Notchl markedly increased in TGF-ß(1); induced group (P<0.05), but the expression of E-cadherin obviously reduced(P<0.05). The expression of Notch1 protein and its mRNA was positively correlated to the expression ofα-SMA(r(protein);=0.958; r(mRNA);=0.944; P<0.05), and was negatively correlated to the expression of E-cadherin(r(protein);=-0.937; r(mRNA);=-0.921; P<0.05). CONCLUSION: Notch1 may participate in the KTECT induced by TGF-ß(1);.

Detection of pulmonary embolism comparison between dual energy CT and MR angiography in a rabbit model.

RATIONALE AND OBJECTIVES: The purpose of this study was to compare the efficacy of dual-energy computed tomography (DECT), time-resolved magnetic resonance (MR) imaging (MRI) perfusion measurements, and high-resolution MR angiography (MRA) for the detection of pulmonary embolism (PE) in a rabbit model. MATERIALS AND METHODS: Two hours after Gelfoam (n = 16) or saline (n = 2) injection into the femoral vein, 18 rabbits were first imaged using dual-energy computed tomographic pulmonary angiography (CTPA), from which blood flow imaging (BFI) were produced. Next, the rabbits underwent time-resolved MR perfusion measurements and MRA using a 3.0-T scanner. Two radiologists who were blinded to histopathologic findings independently evaluated the results of CTPA, BFI, time-resolved MR perfusion, and MRA for each rabbit and recorded the locations and number of pulmonary clots on a per lobe basis. Immediately after MRI examination, pathologic determination of the locations and numbers of lung lobes with PE was recorded. Histopathologic results served as the reference standard to determine the sensitivity and specificity of DECT (BFI and CTPA) and MRI (time-resolved MR perfusion and high-resolution MRA) for the detection of PE. RESULTS: The induction of PE was successful in all animals, but three rabbits were excluded because of death prior to MRI procedures (caused by complications during the embolization procedure); only data from the remaining 15 rabbits were included in the final analysis. Histopathology demonstrated 24 lobes with clots and 51 lobes without clots. CTPA, BFI, and MRI correctly identified PE in 23, 23, and 20 lobes, respectively, and the absence of emboli in 48, 46, and 46 lobes, respectively; these results corresponded to sensitivities of 95.8%, 95.8%, and 83.3% and specificities of 94.1%, 90.2%, and 90.2% for reader 1 and sensitivities of 91.7%, 91.7%, and 87.5% and specificities of 90.2%, 88.2%, and 88.2% for reader 2 for CTPA, BFI, and MRI, respectively. Good or excellent intermodality and interreader agreement among CTPA, BFI, and MRI were found. CONCLUSIONS: DECT can simultaneously provide high-resolution pulmonary artery and lung iodine mapping with slightly high diagnostic accuracy for the detection of PE compared to MRI in an experimental rabbit model of PE. This improvement was not statistically significant given the study sample size.