Efficient nano iron particle-labeling and noninvasive MR imaging of mouse bone marrow-derived endothelial progenitor cells

In this study, we sought to label mouse bone marrow-derived endothelial progenitor cells (EPCs) with Resovist® in vitro and to image them using 7.0 Tesla (T) magnetic resonance imaging (MRI). Mouse bone marrow-derived EPCs were cultured in endothelial basal medium with endothelial growth supplement. They were then characterized by immunocytochemistry, flow cytometry, and fluorescence quantitative polymerase chain reaction. Their functions were evaluated by measuring their uptake of 1,1-dioctadecyl-3,3,3,3-tetramethylindocarbocyanine-labeled acetylated low-density lipoprotein (Dil-Ac-LDL), binding of fluorine isothiocyanate (FITC)-labeled Ulex europaeus agglutinin (UEA), and formation of capillary-like networks. EPCs were labeled with superparamagnetic iron oxide (SPIO) and their proliferation was then assessed in a water-soluble tetrazolium (WST-8)-based cell proliferation assay. Spin echo sequence (multislice, multiecho [MSME]) and gradient echo sequence (2D-FLASH) were used to detect differences in the numbers of labeled cells by 7.0 T MRI. The results showed that the cultured cells were of “cobblestone”-like shape and positive for CD133, CD34, CD31, von Willebrand factor, kinase domain receptor, and CD45, but negative for F4/80. They could take up Dil-Ac-LDL, bind FITC-UEA, and form capillary-like networks on Matrigel in vitro. Prussian-blue staining demonstrated that the cells were efficiently labeled with SPIO. The single-cell T2* effect was more obvious in the 2D-FLASH sequence than in the MSME sequence. Further, there were almost no adverse effects on cell vitality and proliferation. In conclusion, mouse bone marrow-derived EPCs can be efficiently labeled with SPIO and imaged with 7.0-T MRI. They may thus be traced by MRI following transplantation for blood vessel disorders and cancer treatment

Fully Automated Detection of Corticospinal Tract Damage in Chronic Stroke Patients

Structural integrity of the corticospinal tract (CST) after stroke is closely linked to the degree of motor impairment. However, current methods for measurement of fractional atrophy (FA) of CST based on region of interest (ROI) are time-consuming and open to bias. Here, we used tract-based spatial statistics (TBSS) together with a CST template with healthy volunteers to quantify structural integrity of CST automatically. Two groups of patients after ischemic stroke were enrolled, group 1 (10 patients, 7 men, and Fugl-Meyer assessment (FMA) scores ⩽ 50) and group 2 (12 patients, 12 men, and FMA scores = 100). CST of FAipsi, FAcontra, and FAratio was compared between the two groups. Relative to group 2, FA was decreased in group 1 in the ipsilesional CST (P<0.01), as well as the FAratio (P<0.01). There was no significant difference between the two subgroups in the contralesional CST (P=0.23). Compared with contralesional CST, FA of ipsilesional CST decreased in group 1 (P<0.01). These results suggest that the automated method used in our study could detect a surrogate biomarker to quantify the CST after stroke, which would facilitate implementation of clinical practice

A practical grid generation procedure for the design of free-form structures

Computer aided design software enables the rapid conceptual creation of a curved surface geometry, whereas it is neither a convenient nor an obvious task for engineers to create a discrete grid structure on a complex surface that meets architectural and aesthetic requirements. This emphasizes the importance of grid generating tools and methods in the initial design stage. This paper presents an efficient design tool for the synthesis of free-form grid structures based on the "guide line" method, employing a fast and straightforward approach which achieves grids with rods of balanced length and fluent lines. The process starts with defining a limited number of curves (named the "guide lines") on the surface, which are then used to determine the directions of the 'rods' of the grid. Two variations of this concept are introduced in this paper: the ‘Guide Line Scaling Method’ (GSM) and the 'Two Guide Lines with Two End Vertices Method' (2G2VM). Case studies are provided which illustrate the successful execution of these procedures. The results show that the free-form grid structures generated with the proposed methods feature a regular shape and fluent lines, thereby satisfying aesthetic requirements. These two methods have been programmed into the software ZD-Mesher, enabling rapid grid generation for structural design purposes

A Novel Multi-Input Bidirectional LSTM and HMM Based Approach for Target Recognition from Multi-Domain Radar Range Profiles

Radars, as active detection sensors, are known to play an important role in various intelligent devices. Target recognition based on high-resolution range profile (HRRP) is an important approach for radars to monitor interesting targets. Traditional recognition algorithms usually rely on a single feature, which makes it difficult to maintain the recognition performance. In this paper, 2-D sequence features from HRRP are extracted in various data domains such as time-frequency domain, time domain, and frequency domain. A novel target identification method is then proposed, by combining bidirectional Long Short-Term Memory (BLSTM) and a Hidden Markov Model (HMM), to learn these multi-domain sequence features. Specifically, we first extract multi-domain HRRP sequences. Next, a new multi-input BLSTM is proposed to learn these multi-domain HRRP sequences, which are then fed to a standard HMM classifier to learn multi-aspect features. Finally, the trained HMM is used to implement the recognition task. Extensive experiments are carried out on the publicly accessible, benchmark MSTAR database. Our proposed algorithm is shown to achieve an identification accuracy of over 91% with a lower false alarm rate and higher identification confidence, compared to several state-of-the-art techniques

Prefrontal-Temporal Pathway Mediates the Cross-Modal and Cognitive Reorganization in Sensorineural Hearing Loss With or Without Tinnitus: A Multimodal MRI Study

Objective: Hearing loss, one main risk factor of tinnitus and hyperacusis, is believed to involve significant central functional abnormalities. The recruitment of the auditory cortex in non-auditory sensory and higher-order cognitive processing has been demonstrated in the hearing-deprived brain. The dorsolateral prefrontal cortex (dlPFC), which has dense anatomical connections with the auditory pathway, is known to play a crucial role in multi-sensory integration, auditory regulation, and cognitive processing. This study aimed to verify the role of the dlPFC in the cross-modal reorganization and cognitive participation of the auditory cortex in long-term sensorineural hearing loss (SNHL) by combining functional and structural measurements.Methods: Thirty five patients with long-term bilateral SNHL and 35 matched healthy controls underwent structural imaging, resting-state functional magnetic resonance imaging (rs-fMRI), diffusion tensor imaging (DTI), and neuropsychological assessments. Ten SNHL patients were with subjective tinnitus.Results: No differences in gray matter volume, spontaneous neural activity, or diffusion characteristics in the dlPFC were found between the SNHL and control groups. The functional connectivity (FC) between the dlPFC and the auditory cortex and visual areas, such as the cuneus, fusiform, lingual cortex, and calcarine sulcus was increased in patients with SNHL. ANOVA and post hoc tests revealed similar FC alterations in the SNHL patients with and without tinnitus when compared with the normal hearing controls, and SNHL patients with and without tinnitus showed no difference in the dlPFC FC. The FC in the auditory cortex was associated with the symbol digit modality test (SDMT) scores in the SNHL patients, which reflect attentional function, processing speed, and visual working memory. Hearing-related FC with the dlPFC was found in the lingual cortex. A tract-based spatial statistics (TBSS) analysis revealed decreased fractional anisotropy (FA) values, mainly in the temporal inferior fronto-occipital fasciculus (IFOF), which showed remarkable negative correlations with the mean hearing thresholds in SNHL.Conclusion: Higher functional coupling between the dlPFC and auditory and visual areas, accompanied by decreased FA along the IFOF connecting the frontal cortex and the occipito-temporal area, might mediate cross-modal plasticity via top-down regulation and facilitate the involvement of the auditory cortex in higher-order cognitive processing following long-term SNHL

Inefficient Involvement of Insula in Sensorineural Hearing Loss

The insular cortex plays an important role in multimodal sensory processing, audio-visual integration and emotion; however, little is known about how the insula is affected by auditory deprivation due to sensorineural hearing loss (SNHL). To address this issue, we used structural and functional magnetic resonance imaging to determine if the neural activity within the insula and its interregional functional connectivity (FC) was disrupted by SNHL and if these alterations were correlated clinical measures of emotion and cognition. Thirty-five SNHL subjects and 54 Controls enrolled in our study underwent auditory evaluation, neuropsychological assessments, functional and structure MRI, respectively. Twenty five patients and 20 Controls underwent arterial spin labeling scanning. FC of six insula subdivisions were assessed and the FC results were compared to the neuropsychological tests. Interregional connections were also compared among insula-associated networks, including salience network (SN), default mode network (DMN), and central executive network (CEN). Compared to Controls, SNHL subjects demonstrated hyperperfusion in the insula and significantly decreased FC between some insula subdivisions and other brain regions, including thalamus, putamen, precentral gyrus, postcentral gyrus, mid-cingulate cortex, dorsolateral prefrontal cortex, rolandic operculum. Anxiety, depression and cognitive impairments were correlated with FC values. Abnormal interactions among SN, DMN, and CEN were observed in SNHL group. Our result provides support for the “inefficient high-order control” theory of the insula in which the auditory deprivation caused by SNHL contributes to impaired sensory integration and central deficits in emotional and cognitive processing

Effects of soil grain size and solution chemistry on the transport of biochar nanoparticles

Biochar nanoparticles (BC-NP) have attracted significant attention because of their unique environmental behavior, some of which could potentially limit large-scale field application of biochar. Accurate prediction of the fate and transportability of BC-NP in soil matrix is the key to evaluating their environmental influence. This study investigated the effects of soil grain size and environmentally relevant solution chemistry, such as ionic strength (cation concentration, 0.1 mM–50 mM; cation type, Na+, and Ca2+), and humic acid (HA; 0–10 mg/L), on the transport behavior of BC-NP via systematic column experiments. The transportability of BC-NP in the soil-packed column decreased with decreasing soil grain size and was inversely proportional to soil clay content. At low cation concentrations (0.1–1.0 mM), a considerable proportion of BC-NP (15.95%–67.17%) penetrated the soil columns. Compared with Na+, Ca2+ inhibited the transportability of BC-NP in the soil through a charge shielding effect. With increasing HA concentration, the transportability of BC-NP increased, likely due to an enhanced repulsion force between BC-NP and soil particles. However, at a high HA concentration (10 mg/L), Ca2+ bridging reduced the transportability of BC-NP in the soil. Breakthrough curves of BC-NP were explained by the two-site kinetic retention model. The antagonistic effects of ionic strength and HA indicated that the transport behavior of BC-NP in the soil was governed by competitive effects of some environmental factors, including soil grain size, environmental solution chemistry, and natural organic matter content