The Two-Steps Reaction Fluorescent Probe for the Selective Detection of Cysteine and Its Applications.

We reported the specific fluorescent probe (MC-BOD-XDS) with two-steps reaction based on monosulfanyl-coumarin-BODIPY for selective detection of cysteine, high activity sulfanyl-coumarin as the multiple reaction group instead of a group internal standard fluorophore. The reaction mechanism of MC-BOD-XDS for detecting cysteine was different from the reported probes about the nucleophilic aromatic substitution reaction (SNAr) of chlorinated BODIPY. The fluorescent color of MC-BOD-XDS changed from yellow to red, and then to orange. The linear calibration diagram showed that it can potentially be used for quantitatively detection of Cys. Its potential applications were demonstrated by employing it for detection of Cys in artificial urine and in fluorescent imaging in HeLa cells.

Prediction Model for Intermediate-Stage Hepatocellular Carcinoma Response to Transarterial Chemoembolization.

BACKGROUND: The outcome of intermediate-stage hepatocellular carcinoma (HCC) treated with transarterial chemoembolization (TACE) is greatly heterogeneous. Current means for predicting HCC response to TACE are lacking. PURPOSE: To investigate whether the combination of parameters derived from amide proton transfer (APT) and intravoxel incoherent motion (IVIM) imaging, and morphological characteristics of tumor can establish a better prediction model than the univariant model for HCC response to TACE. STUDY TYPE: Prospective. SUBJECTS: 56 patients with intermediate-stage HCC (50 males and six females). FIELD STRENGTH/SEQUENCES: 3.0T; T2 -weighted-fast spin echo, 3D liver acquisition with volume flex, single-shot fast spin echo-planar imaging (EPI), spin echo-EPI. ASSESSMENT: Pretreatment APT signal intensities (SIs), apparent diffusion coefficient (ADC), true molecular diffusion coefficient (D), pseudodiffusion coefficient (D*), and perfusion fraction (f) for tumor, peritumoral, and normal tissues were measured. Follow-up MRI scanning was performed, and the patients were classified as responders or nonresponders based on the modified Response Evaluation Criteria in Solid Tumors (mRECIST) criteria. STATISTICAL TESTS: The imaging parameters were compared among the three tissues and between the two groups using analysis of variance (ANOVA) or two-sample t-test. The prediction model's variables were derived from univariate and multivariate logistic regression analyses. Receiver operating characteristic (ROC) curve analysis was used to explore the predictive performance. RESULTS: Based on the logistic regression analysis results, we established a prediction model that integrated the APT SI and D values in the tumor tissue and the tumor size. ROC analyses revealed that the model was better able to predict tumor response to TACE (area under the ROC curve = 0.851) than the individual parameters on their own. DATA CONCLUSION: A prediction model incorporating pretreatment APT SI, D in the tumor tissue and tumor size may be useful for predicting the response of intermediate-stage HCC to TACE. LEVEL OF EVIDENCE: 1 TECHNICAL EFFICACY: Stage 1 J. MAGN. RESON. IMAGING 2020;52:1657-1667.

Phytoplankton photosynthetic rate measurement using tunable pulsed light induced fluorescence kinetics.

The photosynthetic process of phytoplankton is the basis of the material circulation and energy flow of the ecosystem. The rapid and accurate measurement of phytoplankton photosynthesis rate is of great significance to water ecological environment monitoring, marine resource assessment and global climate change prediction. On the basis of "Bio-Optical" model, a photosynthetic rate measurement method based on tunable pulsed light induced fluorescence kinetics was put forward in this paper. The chlorophyll fluorescence was used as the probe of photosynthesis process, and the phytoplankton photosynthetic rate was evaluated by the photosynthetic electron transport rate. Comparative experiment results showed that the photosynthetic electron transport rate measured by fluorescence kinetic method under different conditions of DCMU, culture light and nutrients (nitrogen) were consistent with the photosynthetic oxygen evolution rate measured by oxygen evolution method, and the correlation coefficient R2 were 0.934, 0.957 and 0.955 respectively.

Intermediate analysis of magnesium alloy covered stent for a lateral aneurysm model in the rabbit common carotid artery.

OBJECTIVE: To analyze the outcomes of a magnesium alloy covered stent (MACS) for a lateral aneurysm model in common carotid artery (CCA). METHODS: In 32 rabbits, a MACS (group A, n = 17) or a Willis covered stent (WCS; group B, n = 15) was inserted and the rabbits were sacrificed 1, 3, 6, or 12 months after stenting. Angiography and intravascular ultrasound (IVUS) were performed at 3, 6, and 12 months. Scanning electron microscopy was performed for six stents in each group at 1, 3, and 6 months, and histopathology and histomorphology were conducted at 3 (n = 4), 6 (n = 4), and 12 (n = 12) months. RESULTS: Final angiography showed complete occlusion of the aneurysms in 12 cases. IVUS at 6 and 12 months revealed a significant increase in mean lumen area of the stented CCA in group A and also showed greater mean lumen area in group A than in group B. The endothelialization process was quicker in group A than in group B. CONCLUSION: MACS is effective for occlusion of lateral aneurysms and is superior to WCS in growth of the stented CCA and endothelialization. Further work is needed to make this device available for human use. KEY POINTS: • The MACS is an effective approach for occlusion of a lateral aneurysm. • IVUS showed that the CCA could grow following degradation of the MACS. • The lumen area of the stented CCA was excellent in MACS. • HE staining displayed the degradation of the magnesium alloy stent. • Combination of IVUS and DSA were applied in this study.

HR-MRI-based nomogram network calculator to predict stroke recurrence in high-risk non-disabling ischemic cerebrovascular events patients.

Background and objective: To investigate the use of high-resolution magnetic resonance imaging (HR-MRI) to identify the characteristics of culprit plaques in intracranial arteries, and to evaluate the predictive value of the characteristics of culprit plaques combined with the modified Essen score for the recurrence risk of high-risk non-disabling ischemic cerebrovascular events (HR-NICE) patients. Methods: A retrospective analysis was conducted on 180 patients with HR-NICE at the First Affiliated Hospital of Xinxiang Medical University, including 128 patients with no recurrence (non-recurrence group) and 52 patients with recurrence (recurrence group). A total of 65 patients with HR-NICE were collected from the Sixth Affiliated Hospital of Shanghai Jiaotong University as a validation group, and their modified Essen scores, high-resolution magnetic resonance vessel wall images, and clinical data were collected. The culprit plaques were analyzed using VesselExplorer2 software. Univariate and multivariate logistic regression analyses were used to identify independent risk factors for recurrence, and a nomogram was constructed using R software to evaluate the discrimination of the model. The area under the curve (AUC) of the receiver operating characteristic curve (ROC) was used to evaluate the model performance. Calibration curves and Decision Curve Analysis (DCA) were used to evaluate the model efficacy. Results: Intra-plaque hemorrhage (OR = 3.592, 95% CI = 1.474-9.104, p = 0.006), homocysteine (OR = 1.098, 95% CI = 1.025-1.179, p = 0.007), and normalized wall index (OR = 1.114, 95% CI = 1.027-1.222, p = 0.015) were significantly higher in the recurrent stroke group than in the non-recurrent stroke group, and were independent risk factors for recurrent stroke. The performance of the nomogram model (AUC = 0.830, 95% CI: 0.769-0.891; PR-AUC = 0.628) was better than that of the modified Essen scoring model (AUC = 0.660, 95% CI: 0.583-0.738) and the independent risk factor combination model (AUC = 0.827, 95% CI: 0.765-0.889). The nomogram model still had good model performance in the validation group (AUC = 0.785, 95% CI: 0.671-0.899), with a well-fitting calibration curve and a DCA curve indicating good net benefit efficacy for patients. Conclusion: High-resolution vessel wall imaging combined with a modified Essen score can effectively assess the recurrence risk of HR-NICE patients, and the nomogram model can provide a reference for identifying high-risk populations with good clinical application prospects.

Multimodality MRI Radiomics Based on Machine Learning for Identifying True Tumor Recurrence and Treatment-Related Effects in Patients with Postoperative Glioma.

INTRODUCTION: Conventional magnetic resonance imaging (MRI) features have difficulty distinguishing glioma true tumor recurrence (TuR) from treatment-related effects (TrE). We aimed to develop a machine-learning model based on multimodality MRI radiomics to help improve the efficiency of identifying glioma TuR. METHODS: A total of 131 patients were enrolled and randomly divided into the training set (n = 91) and the test set (n = 40). Radiomic features were extracted from the postoperative enhancement (PoE) region and edema (ED) region from four routine MRI sequences. After analyses of Spearman's rank correlation coefficient, and least absolute shrinkage and selection operator, the key radiomic features were selected to construct support vector machine (SVM) and k-nearest neighbor (KNN) models. Decision curve analysis (DCA) and receiver operating characteristic (ROC) curves were used to analyze the performance. RESULTS: The PoE model had a significantly higher area under curve (AUC) than the ED model (p < 0.05). Among the models constructed with a single sequence, the model using PoE regional features from CE-T1WI was superior to other models, with an AUC of 0.905 for SVM and 0.899 for KNN. In multimodality models, the PoE model outperformed the ED model with an AUC of 0.931 for SVM and 0.896 for KNN. The multimodality model, which combined routine sequences and the whole regional features, showed a slightly better performance with an AUC of 0.965 for SVM and 0.955 for KNN. Decision curve analysis showed the good clinical utility of multimodal radiomics models. CONCLUSIONS: Multimodality radiomics can identify glioma TuR and TrE, potentially aiding clinical decision-making for individualized treatment. And edematous regions may provide useful information for recognizing recurrence. RETROSPECTIVELY REGISTERED: 2021.04.15, No:2020039.

Use of biexponential and stretched exponential models of intravoxel incoherent motion and dynamic contrast-enhanced magnetic resonance imaging to assess the proliferation of endometrial carcinoma.

Background: It is important to assess the proliferation of endometrial carcinoma (EC) noninvasively using imaging methods. This prospective diagnostic study investigated the value of biexponential and stretched exponential models of intravoxel incoherent motion (IVIM) and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in predicting the Ki-67 status of EC. Methods: In all, 70 patients with EC underwent pelvic MRI. The diffusion coefficient (D), pseudo diffusion coefficient (D*), perfusion fraction (f), distributed diffusion coefficient (DDC), water molecular diffusion heterogeneity index (α), volume transfer constant (Ktrans), rate transfer constant (Kep), and volume of extravascular extracellular space per unit volume of tissue (Ve) were compared. The area under the receiver operating characteristic (ROC) curve (AUC) was used to quantify diagnostic efficacy. Multivariate logistic regression and bootstrap (1,000 samples) analyses were used to establish and evaluate, respectively, the optimal model to predict Ki-67 status. Results: D, Ktrans, and Kep were lower while α was higher in the high-proliferation group as compared with low-proliferation group (all P values<0.05). D and Kep were independent predictors of Ki-67 status in EC, and the combination of these parameters had optimal diagnostic efficacy (AUC =0.920; sensitivity 85.71%; specificity 89.29%), which was significantly better than that of D (AUC =0.753; Z=2.874; P=0.004), α (AUC =0.715; Z=3.505; P=0.001), Ktrans (AUC =0.808; Z=2.741; P=0.006), and Kep (AUC =0.832; Z=2.147; P=0.032) alone. The validation model showed good accuracy (AUC =0.882; 95% confidence interval 0.861-0.897) and consistency (C-statistic =0.902). D, Kep, Ktrans, and α showed a slightly negative (r=-0.271), moderately negative (r=-0.534), slightly negative (r=-0.409), and slightly positive (r=0.488) correlation with the Ki-67 index, respectively (all P values <0.05). Conclusions: IVIM- and DCE-MRI-derived parameters, including D, α, Ktrans, and Kep, were associated with Ki-67 status in EC, and the combination of D and Kep may serve as a superior imaging marker for the identification of low- and high-proliferation EC.

Quantitative dynamic contrast-enhanced parameters and intravoxel incoherent motion facilitate the prediction of TP53 status and risk stratification of early-stage endometrial carcinoma.

BACKGROUND: The aim of the study was to investigate the value of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and intravoxel incoherent motion (IVIM) in differentiating TP53-mutant from wild type, low-risk from non-low-risk early-stage endometrial carcinoma (EC). PATIENTS AND METHODS: A total of 74 EC patients underwent pelvic MRI. Parameters volume transfer constant (Ktrans), rate transfer constant (Kep), the volume of extravascular extracellular space per unit volume of tissue (Ve), true diffusion coefficient (D), pseudo-diffusion coefficient (D*), and microvascular volume fraction (f) were compared. The combination of parameters was investigated by logistic regression and evaluated by bootstrap (1000 samples), receiver operating characteristic (ROC) curves, calibration curves, and decision curve analysis (DCA). RESULTS: In the TP53-mutant group, Ktrans and Kep were higher and D was lower than in the TP53-wild group; Ktrans, Ve, f, and D were lower in the non-low-risk group than in the low-risk group (all P < 0.05). In the identification of TP53-mutant and TP53-wild early-stage EC, Ktrans and D were independent predictors, and the combination of them had an optimal diagnostic efficacy (AUC, 0.867; sensitivity, 92.00%; specificity, 80.95%), which was significantly better than D (Z = 2.169, P = 0.030) and Ktrans (Z = 2.572, P = 0.010). In the identification of low-risk and non-low-risk early-stage EC, Ktrans, Ve, and f were independent predictors, and the combination of them had an optimal diagnostic efficacy (AUC, 0.947; sensitivity, 83.33%; specificity, 93.18%), which was significantly better than D (Z = 3.113, P = 0.002), f (Z = 4.317, P < 0.001), Ktrans (Z = 2.713, P = 0.007), and Ve (Z = 3.175, P = 0.002). The calibration curves showed that the above two combinations of independent predictors, both have good consistency, and DCA showed that these combinations were reliable clinical prediction tools. CONCLUSIONS: Both DCE-MRI and IVIM facilitate the prediction of TP53 status and risk stratification in early-stage EC. Compare with each single parameter, the combination of independent predictors provided better predictive power and may serve as a superior imaging marker.

Heading perception from optic flow is affected by heading distribution.

Recent studies have revealed a central tendency in the perception of physical features. That is, the perceived feature was biased toward the mean of recently experienced features (i.e., previous feature distribution). However, no study explored whether the central tendency was in heading perception or not. In this study, we conducted three experiments to answer this question. The results showed that the perceived heading was not biased toward the mean of the previous heading distribution, suggesting that the central tendency was not in heading perception. However, the perceived headings were overall biased toward the left side, where headings rarely appeared in the right-heavied distribution (Experiment 3), suggesting that heading perception from optic flow was affected by previously seen headings. It indicated that the participants learned the heading distributions and used them to adjust their heading perception. Our study revealed that heading perception from optic flow was not purely perceptual and that postperceptual stages (e.g., attention and working memory) might be involved in the heading perception from optic flow.

Abnormal Dynamic Functional Connectivity in Patients With End-Stage Renal Disease.

Dynamic functional connectivity (FC) analysis can capture time-varying properties of connectivity; however, studies focusing on dynamic FC in patients with end-stage renal disease (ESRD) are very limited. This is the first study to explore the dynamic aspects of whole-brain FC and topological properties in ESRD patients. Resting-state functional magnetic resonance imaging data were acquired from 100 ESRD patients [50 hemodialysis (HD) patients and 50 non-dialysis patients] and 64 healthy controls (HCs). Independent component analysis, a sliding-window approach and graph-theory methods were used to study the dynamic FC properties. The intrinsic brain FC were clustered into four configuration states. Compared with HCs, both patient groups spent longer time in State 3, in which decreased FC between subnetworks of the default mode network (DMN) and between the dorsal DMN and language network was observed in these patients, and a further reduction in FC between the DMN subnetworks was found in HD patients compared to non-dialysis patients. The number of transitions and the variability of global and local efficiency progressively decreased from that in HCs to that of non-dialysis patients to that of HD patients. The completion time of Trail Making Test A and Trail Making Test B positively correlated with the mean dwell time of State 3 and negatively correlated with the number of transitions in ESRD patients. Our findings suggest impaired functional flexibility of network connections and state-specific FC disruptions in patients with ESRD, which may underlie their cognitive deficits. HD may have an adverse effect on time-varying FC.

Evaluation of Amide Proton Transfer-Weighted Imaging for Risk Factors in Stage I Endometrial Cancer: A Comparison With Diffusion-Weighted Imaging and Diffusion Kurtosis Imaging.

Background: Endometrial cancer (EC) is one of the most common gynecologic malignancies in clinical practice. This study aimed to compare the value of diffusion-weighted imaging (DWI), diffusion kurtosis imaging (DKI), and amide proton transfer-weighted imaging (APTWI) in the assessment of risk stratification factors for stage I EC including histological subtype, grade, stage, and lymphovascular space invasion (LVSI). Methods: A total of 72 patients with stage I EC underwent pelvic MRI. The apparent diffusion coefficient (ADC), mean diffusivity (MD), mean kurtosis (MK), and magnetization transfer ratio asymmetry (MTRasym at 3.5 ppm) were calculated and compared in risk groups with the Mann-Whitney U test or independent samples t-test. Spearman's rank correlation was applied to depict the correlation of each parameter with risk stratification. The diagnostic efficacy was evaluated with receiver operating characteristic (ROC) curve analysis and compared using the DeLong test. A multivariate logistic regression was conducted to explore the optimal model for risk prediction. Results: There were significantly greater MTRasym (3.5 ppm) and MK and significantly lower ADC and MD in the non-adenocarcinoma, stage IB, LVSI-positive, high-grade, and non-low-risk groups (all p < 0.05). The MK and MTRasym (3.5 ppm) were moderately positively correlated with risk stratification as assessed by the European Society for Medical Oncology (EMSO) clinical practice guidelines (r = 0.640 and 0.502, respectively), while ADC and MD were mildly negatively correlated with risk stratification (r = -0.358 and -0.438, respectively). MTRasym (3.5 ppm), MD, and MK were identified as independent risk predictors in stage I EC, and optimal predictive performance was obtained with their combinations (AUC = 0.906, sensitivity = 70.97%, specificity = 92.68%). The results of the validation model were consistent with the above results, and the calibration curve showed good accuracy and consistency. Conclusions: Although similar performance was obtained with each individual parameter of APTWI, DWI, and DKI for the noninvasive assessment of aggressive behavior in stage I EC, the combination of MD, MK, and MTRasym (3.5 ppm) provided improved predictive power for non-low-risk stage I EC and may serve as a superior imaging marker.

Stabilizing and Anti-Repressor Elements Effectively Increases Transgene Expression in Transfected CHO Cells.

Chinese hamster ovary (CHO) cells are currently the most widely used host cells for recombinant therapeutic protein (RTP) production. Currently, the RTP yields need to increase further to meet the market needs and reduce costs. In this study, three stabilizing and anti-repressor (SAR) elements from the human genome were selected, including human SAR7, SAR40, and SAR44 elements. SAR elements were cloned upstream of the promoter in the eukaryotic vector, followed by transfection into CHO cells, and were screened under G418 pressure. Flow cytometry was used to detect enhanced green fluorescent protein (eGFP) expression levels. The gene copy numbers and mRNA expression levels were determined through quantitative real-time PCR. Furthermore, the effect of the stronger SAR elements on adalimumab was investigated. The results showed that transgene expression levels in the SAR-containing vectors were higher than that of the control vector, and SAR7 and SAR40 significantly increased and maintained the long-term expression of the transgene in CHO cells. In addition, the transgene expression level increase was related with gene copy numbers and mRNA expression levels. Collectively, SAR elements can enhance the transgene expression and maintain the long-term expression of a transgene in transfected CHO cells, which may be used to increase recombinant protein production in CHO cells.

Comparison of Diffusion Kurtosis Imaging and Amide Proton Transfer Imaging in the Diagnosis and Risk Assessment of Prostate Cancer.

OBJECTIVES: This study aims to evaluate and compare the diagnostic value of DKI and APT in prostate cancer (PCa), and their correlation with Gleason Score (GS). MATERIALS AND METHODS: DKI and APT imaging of 49 patients with PCa and 51 patients with benign prostatic hyperplasia (BPH) were collected and analyzed, respectively. According to the GS, the patients with PCa were divided into high-risk, intermediate-risk and low-risk groups. The mean kurtosis (MK), mean diffusion (MD) and magnetization transfer ratio asymmetry (MTRasym, 3.5 ppm) values among PCa, BPH, and different GS groups of PCa were compared and analyzed respectively. The diagnostic accuracy of each parameter was evaluated by using the receiver operating characteristic (ROC) curve. The correlation between each parameter and GS was analyzed by using Spearman's rank correlation. RESULTS: The MK and MTRasym (3.5 ppm) values were significantly higher in PCa group than in BPH group, while the MD value was significantly lower than in BPH group. The differences of MK/MD/MTRasym (3.5 ppm) between any two of the low-risk, intermediate-risk, and high-risk groups were all statistically significant (p <0.05). The MK value showed the highest diagnostic accuracy in differentiating PCa and BPH, BPH and low-risk, low-risk and intermediate-risk, intermediate-risk and high-risk (AUC = 0.965, 0.882, 0.839, 0.836). The MK/MD/MTRasym (3.ppm) values showed good and moderate correlation with GS (r = 0.844, -0.811, 0.640, p <0.05), respectively. CONCLUSION: DKI and APT imaging are valuable in the diagnosis of PCa and demonstrate strong correlation with GS, which has great significance in the risk assessment of PCa.

Development of a novel enzyme reactor and application as a chemiluminescence flow-through biosensor.

A novel enzyme reactor was prepared using calcium alginate fiber (CAF) and amine-modified nanosized mesoporous silica (AMNMS) as a support. Combination of the adsorption of the enzyme on AMNMS with the cage effect of the polymer greatly increases the catalytic activity and the stability of the immobilized enzyme. It was shown that the lifetime, stability, and catalytic activity of the enzyme reactor were greatly improved by incorporating AMNMS into CAF to efficiently encapsulate the enzyme. Glucose oxidase was chosen as a model enzyme to explore the possibility of using CAF-AMNMS as a matrix for enzyme immobilization in the design of a chemiluminescence (CL) flow-through biosensor. The sensitivity of the flow-through biosensor combined with a novel luminol-diperiodatonickelate CL system was higher than for other reported CL biosensors. The proposed biosensor exhibits short response time, easy operation, long lifetime, high catalytic activity, high sensitivity, and simple assembly.

Diagnostic value of conventional MRI combined with DTI for neonatal hyperbilirubinemia.

BACKGROUND: Neonatal hyperbilirubinemia (NHB) is a common clinical disease and can cause bilirubin encephalopathy in severe cases. It is now widely accepted that increased signal intensity in the globus pallidus on MR T1WI is an important sign of neonatal bilirubin encephalopathy. And brain diffusion tensor imaging (DTI) has not been used extensively to study hyperbilirubinemia (HB). So we compared newborns with different hyperbilirubinemia of different severities and healthy newborns in order to determine the relationships among MRI signal intensities, serum bilirubin levels, and the molecular changes in brain water diffusion in hyperbilirubinemia. METHODS: Seventy-three newborns with hyperbilirubinemia were grouped into three groups: the mild increase group (M, 27 cases), the moderate increase group (O, 28 cases), and the severe group (S, 18 cases). The groups were based on serum bilirubin levels. We performed cranial MRI in these newborns, as well as 29 healthy full-term infants (group N). We compared and analyzed the mean signal values for the globus pallidus and the relationship between the bilirubin level and the score on the neonatal behavioral neurological assessment. Fifteen, 10, and 10 patients in groups M, O + S, and N were successfully examined using diffusion tensor imaging (DTI). We assessed the relationships among the signal from the globus pallidus, fractional anisotropy (FA), and average diffusion coefficient (DCav) of the posterior limb of the internal capsule (PLIC). RESULTS: There were significant differences in the mean signal value of bilateral globus pallidus between group O/S and group N [p = 0.029 and 0.000 (left), 0.038 and 0.000 (right)]. There were no significant differences in bilateral FA or DCav values between the patient groups and group N. The bilateral PLIC-FA and DCav values were significantly different between the patient groups and group N (P = 0.014 and 0.047, respectively). CONCLUSIONS: Increased signal intensity in the globus pallidus on T1-weighted imaging can be used as an objective index to evaluate neonatal bilirubin encephalopathy. Globus pallidus and PLIC injuries are likely to occur when the total serum bilirubin level is ≥20 mg/dl.

Effect of Ce Addition on Modifying the Microstructure and Achieving a High Elongation with a Relatively High Strength of As-Extruded AZ80 Magnesium Alloy.

Forming magnesium alloys with rare earth elements (La, Gd, Nd, Y, Ce) is a routine method for modifying their microstructure and properties. In the present work, the effect of Ce addition on the microstructure evolution and the mechanical properties of as-extruded Mg-8Al-0.5Zn (AZ80) alloy was investigated. All of the extruded AZ80-xCe (x = 0, 0.2, 0.8 and 1.4 wt %) alloys exhibited equiaxed grains formed by fully dynamic recrystallization, and the grain size of the extruded AZ80 alloy was remarkably reduced by ~56.7% with the addition of 1.4 wt % Ce. Furthermore, the bulk-shaped Al4Ce phase formed when Ce was first added, with the Ce content rising to 0.8 wt % or higher, and Al4Ce particles in both the nano- and micron sizees were well distributed in the primary α-Mg matrix. The area fraction of the Al4Ce particles expanded with increasing Ce content, providing more nuclei for dynamic recrystallization, which could contribute to the grain refinement. The results of the tensile tests in this study showed that Ce addition effectively improved the room temperature formability of the as-extruded AZ80 alloy, without sacrificing strength. The significantly improved mechanical properties were ascribed to excellent grain refinement, weakened texture strength, an increased Schmid factor, and a reduced area fraction of low-angle grain boundaries, all resulting from Ce addition to the as-extruded AZ80 alloy. The contribution of the nano-Al4Ce precipitates on improving the mechanical properties was also discussed in this paper.

Comparative analysis of 3D time-resolved contrast-enhanced magnetic resonance angiography, color Doppler ultrasound and digital subtraction angiography in symptomatic carotid stenosis.

The present study aimed to compare the diagnostic value of contrast-enhanced magnetic resonance angiography (CE MRA) with 3D time-resolved imaging of contrast kinetics, color Doppler ultrasound (CDUS) and digital subtraction angiography (DSA) in extracranial carotid stenosis (CS). A total of 54 patients with symptomatic CS were subjected to CDUS, CE MRA and DSA examination. Results of DSA were defined as the standard, and a total of 216 vessels were examined. In each patient four vessels were examined, namely the bilateral common carotid arteries and the bilateral internal carotid arteries. The sensitivities and specificities of CE MRA and CDUS for various degrees of CS were also determined. It was observed that the sensitivities to mild-level (1-49%), moderate-level (50-69%) and severe-level (70-99%) CS were 85.45, 100 and 100% for CE MRA, and 78.18, 50 and 100% for CDUS, respectively. The corresponding specificities were 95.27, 98.58 and 99.53% for CE MRA, and 79.05, 93.36 and 98.10% for CDUS, respectively. In addition, the carotid sinus plaque detection rate for CDUS was significantly higher than that of DSA and CE MRA (both P<0.001). Detection rates for common carotid artery plaques and internal carotid artery plaques did not significantly differ among the three examination methods (all P>0.05). These data demonstrate that CE MRA has higher sensitivity and specificity than CDUS for the diagnosis of CS, and that CDUS has a higher carotid sinus plaque detection rate than DSA and CE MRA. Therefore, the combination of MRI and CDUS may be a 'gold standard' diagnostic method for the detection of moderate and severe CS.

A comparison of contrast-free MRA at 3.0T in cases of intracranial aneurysms with or without subarachnoid hemorrhage.

PURPOSE: To determine the diagnostic accuracy of contrast-free MRA at 3.0T for detection of intracranial aneurysms in patients with subarachnoid hemorrhage. METHODS: 411 patients (183 with SAH and 228 with non-SAH) underwent MRA. Accuracy, sensitivity, specificity, positive predictive values (PPV), and negative predictive values (NPV) were measured and compared with DSA. RESULTS: Except for a slight difference in sensitivity in patient-based and aneurysm-based evaluations (P=0.037), there were no other significant differences in accuracy, specificity, PPV, and NPV. CONCLUSION: VR 3D-TOF-MRA is a non-invasive approach with high accuracy in the diagnosis of intracranial aneurysms.

The development and amino acid binding ability of nano-materials based on azo derivatives: theory and experiment.

Two nano-material-containing azo groups have been designed and developed, and the binding ability of nano-materials with various amino acids has been characterized by UV-vis and fluorescence titrations. Results indicated that two nano-materials showed the strongest binding ability for homocysteine among twenty normal kinds of amino acids (alanine, valine, leucine, isoleucine, methionine, aspartic acid, glutamic acid, arginine, glycine, serine, threonine, asparagine, phenylalanine, histidine, tryptophan, proline, lysine, glutamine, tyrosine and homocysteine). The reason for the high sensitivity for homocysteine was that two nano-materials containing an aldehyde group reacted with SH in homocysteine and afforded very stable thiazolidine derivatives. Theoretical investigation further illustrated the possible binding mode in host-guest interaction and the roles of molecular frontier orbitals in molecular interplay. Thus, the two nano-materials can be used as optical sensors for the detection of homocysteine.

Platelet-derived growth factor-ß expression in rabbit models of cerebral vasospasm following subarachnoid hemorrhage.

Subarachnoid hemorrhage (SAH), one of the serious types of stroke incurred by bleeding into the space surrounding the brain, occurs when brains are deprived of oxygen by various factors, particularly an interruption to the blood supply or a ruptured aneurysm. Cerebral vasospasm (CVS) is one of the most common complications of SAH. It has been proposed that platelet­derived growth factor (PDGF) is involved in CVS. The aim of the present study was to analyze expression of PDGF in rabbit models of CVS. Post-SAH CVS rabbit models were created using endovascular puncture and employed to analyze the expression patterns of PDGF by enzyme-linked immunosorbent assay and immunohistochemistry. The results indicated that the creation of the rabbit model of CVS induced using endovascular puncture was successful and demonstrated the double phase changes observed in human CVS. The acute stage started at 12 h post-SAH with narrowing of the vascular lumen diameter. This narrowing appeared again on the seventh day in delayed CVS alongside increased thickness of vessel walls. PDGF-ß expression was observed in vascular smooth muscle cells of the rabbit models. PDGF-ß was expressed as early as 3 h post-SAH, it was evident after 1 day and reached a peak in 7 days, suggesting that PDGF-ß is involved in the early stages of CVS. In the current study, it was confirmed that PDGF-ß expression was present in the rabbit models of CVS, which may aid the elucidation of the pathogenesis of CVS, and also provide useful information for diagnosis and treatment of CVS.