Micro-magnetic Resonance Research Articles

Zi Qi Decoction Alleviates Liver Fibrosis by Inhibiting the Toll-Like Receptor 4 (TLR4)-Related Nuclear Factor kappa b (NF-κB) and Mitogen-Activated Protein Kinase (MAPK) Signaling Pathways

BackgroundHepatic stellate cells (HSCs) play a vital role in hepatic fibrogenesis. Our recent clinical study indicated that the Zi Qi decoction, a Traditional Chinese Medicine formula, exhibited good efficacy in alleviating liver fibrosis, but the underlying mechanism remains elusive.Material/MethodsRats repeatedly injected with CCl4 and cells stimulated with lipopolysaccharide were used as in vivo and in vitro models for liver fibrosis, respectively. The viability of LX-2 cells was evaluated with MTT assay. Relative messenger RNA (mRNA) expression of representative extracellular matrix (ECM) components was detected with real-time quantitative polymerase chain reaction (RT-qPCR). Moreover, total and phosphorylation levels of ECM proteins and pathway-related proteins were detected with western blotting. Immunofluorescent staining was used to show the nuclear translocation of nuclear factor kappa b (NF-κB) p65. Hematoxylin & eosin (H&E) and Masson trichrome staining and immunohistochemistry were performed to evaluate the extent of liver fibrosis. The levels of alanine transaminase (ALT), aspartate transaminase (AST), gamma-glutamyl transpeptidase (GGT), Hyp, tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) were tested with an enzyme-linked immunosorbent assay. In addition, 7.0T micro-magnetic resonance imaging (micro-MRI) was used to evaluate the severity of hepatic damage.ResultsThe Zi Qi decoction inhibited lipopolysaccharide-mediated upregulation of mRNA and protein levels of representative ECM proteins both in vivo and in vitro. The Zi Qi decoction also suppressed activation of the Toll-like receptor 4 (TLR4)-related NF-κB signaling pathway and subsequently inhibited the nuclear translocation of activated NF-κB. Moreover, another TLR4 downstream pathway, mitogen-activated protein kinase (MAPK), was simultaneously restrained. The results of liver pathology and MRI in rat models also suggested the efficacy of the Zi Qi decoction in attenuating liver damage.ConclusionsThe Zi Qi decoction inhibited liver fibrosis by inhibiting the TLR4-related NF-κB and MAPK signaling pathways and preventing activation of HSCs.

Renovascular Disease Induces Senescence in Renal Scattered Tubular-Like Cells and Impairs Their Reparative Potency.

Scattered tubular-like cells (STCs), dedifferentiated renal tubular epithelial cells, contribute to renal self-healing, but severe injury might blunt their effectiveness. We hypothesized that ischemic renovascular disease (RVD) induces senescence in STC and impairs their reparative potency. CD24+/CD133+ STCs were isolated from swine kidneys after 16 weeks of RVD or healthy controls. To test their reparative capabilities in injured kidneys, control or RVD-STC (5×105) were prelabeled and injected into the aorta of 2 kidneys, 1-clip (2k,1c) mice 2 weeks after surgery. Murine renal function and oxygenation were studied in vivo 2 weeks after injection using micro-magnetic resonance imaging, and fibrosis, tubulointerstitial injury, capillary density, and expression of profibrotic and inflammatory genes ex vivo. STC isolated from swine RVD kidneys showed increased gene expression of senescence and senescence-associated secretory phenotype markers and positive SA-β-gal staining. Delivery of normal pig STCs in 2k,1c mice improved murine renal perfusion, blood flow, and glomerular filtration rate, and downregulated profibrotic and inflammatory gene expression. These renoprotective effects were blunted using STC harvested from RVD kidneys, which also failed to attenuate hypoxia, fibrosis, tubular injury, and capillary loss in injured mouse 2k,1c kidneys. Hence, RVD may induce senescence in endogenous STC and impair their reparative capacity. These observations implicate cellular senescence in the pathophysiology of ischemic kidney disease and support senolytic therapy to permit self-healing of senescent kidneys.

3D Printed Biomimetic Rabbit Airway Simulation Model for Nasotracheal Intubation Training.

Rabbit inhalation anesthesia by endotracheal intubation involves a higher risk among small animals owing to several anatomical and physiological features, which is pathognomonic to this species of lagomorphs. Rabbit-specific airway devices have been designed to prevent misguided intubation attempts. However, it is believed that expert anesthetic training could be a boon in limiting the aftermaths of this procedure. Our research is aimed to develop a novel biomimetic 3D printed rabbit airway model with representative biomechanical material behavior and radiodensity. Imaging data were collected for two sacrificed rabbit heads using micro-computed tomography (μCT) and micro-magnetic resonance imaging for the first head and cone beam computed tomography (CBCT) for the second head. Imaging-based life-size musculoskeletal airway models were printed using polyjet technology with a combination of hard and soft materials in replicates of three. The models were evaluated quantitatively for dimensional accuracy and radiodensity and qualitatively using digital microscopy and endoscopy for technical, tactic, and visual realism. The results displayed that simulation models printed with polyjet technology have an overall surface representation of 93% for μCT-based images and 97% for CBCT-based images within a range of 0.0–2.5 mm, with μCT showing a more detailed reproduction of the nasotracheal anatomy. Dimensional discrepancies can be caused due to inadequate support material removal and due to the limited reconstruction of microstructures from the imaging on the 3D printed model. The model showed a significant difference in radiodensities in hard and soft tissue regions. Endoscopic evaluation provided good visual and tactile feedback, comparable to the real animal. Overall, the model, being a practical low-cost simulator, comprehensively accelerates the learning curve of veterinary nasotracheal intubation and paves the way for 3D simulation-based image-guided interventional procedures.

ViceCT and whiceCT for simultaneous high-resolution visualization of craniofacial, brain and ventricular anatomy from micro-computed tomography

Up to 40% of congenital diseases present disturbances of brain and craniofacial development resulting in simultaneous alterations of both systems. Currently, the best available method to preclinically visualize the brain and the bones simultaneously is to co-register micro-magnetic resonance (µMR) and micro-computed tomography (µCT) scans of the same specimen. However, this requires expertise and access to both imaging techniques, dedicated software and post-processing knowhow. To provide a more affordable, reliable and accessible alternative, recent research has focused on optimizing a contrast-enhanced µCT protocol using iodine as contrast agent that delivers brain and bone images from a single scan. However, the available methods still cannot provide the complete visualization of both the brain and whole craniofacial complex. In this study, we have established an optimized protocol to diffuse the contrast into the brain that allows visualizing the brain parenchyma and the complete craniofacial structure in a single ex vivo µCT scan (whiceCT). In addition, we have developed a new technique that allows visualizing the brain ventricles using a bilateral stereotactic injection of iodine-based contrast (viceCT). Finally, we have tested both techniques in a mouse model of Down syndrome, as it is a neurodevelopmental disorder with craniofacial, brain and ventricle defects. The combined use of viceCT and whiceCT provides a complete visualization of the brain and bones with intact craniofacial structure of an adult mouse ex vivo using a single imaging modality.

The shrimp nephrocomplex serves as a major portal of pathogen entry and is involved in the molting process

Viruses, such as white spot syndrome virus, and bacteria, such as Vibrio species, wreak havoc in shrimp aquaculture [C. M. Escobedo-Bonilla et al., J. Fish. Dis. 31, 1-18 (2008)]. As the main portal of entry for shrimp-related pathogens remain unclear, infectious diseases are difficult to prevent and control. Because the cuticle is a strong pathogen barrier, regions lacking cuticular lining, such as the shrimp's excretory organ, "the antennal gland," are major candidate entry portals [M. Corteel et al., Vet. Microbiol. 137, 209-216 (2009)]. The antennal gland, up until now morphologically underexplored, is studied using several imaging techniques. Using histology-based three-dimensional technology, we demonstrate that the antennal gland resembles a kidney, connected to a urinary bladder with a nephropore (exit opening) and a complex of diverticula, spread throughout the cephalothorax. Micromagnetic resonance imaging of live shrimp not only confirms the histology-based model, but also indicates that the filling of the diverticula is linked to the molting cycle and possibly involved therein. Based on function and complexity, we propose to rename the antennal gland as the "nephrocomplex." By an intrabladder inoculation, we showed high susceptibility of this nephrocomplex to both white spot syndrome virus and Vibrio infection compared to peroral inoculation. An induced drop in salinity allowed the virus to enter the nephrocomplex in a natural way and caused a general infection followed by death; fluorescent beads were used to demonstrate that particles may indeed enter through the nephropore. These findings pave the way for oriented disease control in shrimp.

A temperature-controlled cryogen free cryostat integrated with transceiver-mode superconducting coil for high-resolution magnetic resonance imaging.

Small-sized High Temperature Superconducting (HTS) radiofrequency coils are used in a number of micro-magnetic resonance imaging applications and demonstrate a high detection sensitivity that improves the signal-to-noise ratio. However, the use of HTS coils could be limited by the rarity of cryostats that are suitable for the MR environment. This study presents a magnetic resonance (MR)-compatible and easily operated cryogen-free cryostat based on the pulse tube cryocooler technology for the cooling and monitoring of HTS coils below the temperature of liquid nitrogen. This cryostat features a real-time temperature control function that allows the precise frequency adjustment of the HTS coil. The influence of the temperature on the electrical properties, resonance frequency (f0), and quality factor (Q) of the HTS coil was investigated. Temperature control is obtained with an accuracy of over 0.55 K from 60 K to 86 K, and the sensitivity of the system, extracted from the frequency measurement from 60 K to 75 K, is of about 2 kHz/K, allowing a fine retuning (within few Hz, compared to 10 kHz bandwidth) in good agreement with experimental requirements. We demonstrated that the cryostat, which is mainly composed of non-magnetic materials, does not perturb the electromagnetic field in any way. MR images of a 10 × 10 × 15 mm3 liquid phantom were acquired using the HTS coil as a transceiver with a spatial resolution of 100 × 100 × 300 µm3 in less than 20 min under experimental conditions at 1.5 T.

Temporomandibular joint damage in K/BxN arthritic mice

Rheumatoid arthritis (RA) is an autoimmune disease affecting 1% of the world population and is characterized by chronic inflammation of the joints sometimes accompanied by extra-articular manifestations. K/BxN mice, originally described in 1996 as a model of polyarthritis, exhibit knee joint alterations. The aim of this study was to describe temporomandibular joint (TMJ) inflammation and damage in these mice. We used relevant imaging modalities, such as micro-magnetic resonance imaging (μMRI) and micro-computed tomography (μCT), as well as histology and immunofluorescence techniques to detect TMJ alterations in this mouse model. Histology and immunofluorescence for Col-I, Col-II, and aggrecan showed cartilage damage in the TMJ of K/BxN animals, which was also evidenced by μCT but was less pronounced than that seen in the knee joints. μMRI observations suggested an increased volume of the upper articular cavity, an indicator of an inflammatory process. Fibroblast-like synoviocytes (FLSs) isolated from the TMJ of K/BxN mice secreted inflammatory cytokines (IL-6 and IL-1β) and expressed degradative mediators such as matrix metalloproteinases (MMPs). K/BxN mice represent an attractive model for describing and investigating spontaneous damage to the TMJ, a painful disorder in humans with an etiology that is still poorly understood.

Chondroprotective and anti-inflammatory effects of amurensin H by regulating TLR4/Syk/NF-κB signals.

The low‐grade, chronic inflammation initiated by TLR4‐triggered innate immune responses has a central role on early osteoarthritis. Amurensin H is a resveratrol dimer with anti‐inflammatory and anti‐apoptotic effects, while its effects on TLR‐4 signals to inhibit osteoarthritis are still unclear. In the present study, treatment with amurensin H for 2 weeks in monosodium iodoacetate‐induced mice significantly slows down cartilage degeneration and inflammation using macroscopic evaluation, haematoxylin and eosin (HE) staining and micro‐magnetic resonance imaging. In IL‐1β‐stimulated rat chondrocytes, amurensin H suppresses the production of inflammatory mediators including nitric oxide, IL‐6, IL‐17, PGE2 and TNF‐α using Greiss and ELISA assay. Amurensin H inhibits matrix degradation via decreasing levels of MMP‐9 and MMP‐13 using Western blot assay, promotes synthesis of type II collagen and glycosaminoglycan using immunostaining and safranin O staining, respectively. Amurensin H inhibits intracellular and mitochondrial reactive oxygen species (ROS) generation, and mitochondrial membrane depolarization using DCFH‐DA, MitoSOX Red and JC‐1 assay as well. IL‐1β stimulates TLR4 activation and Syk phosphorylation in chondrocytes, while amurensin H inhibits TLR4/Syk signals and downstream p65 phosphorylation and translocation in a time and dose‐dependent manner. Together, these results suggest that amurensin H exerts chondroprotective effects by attenuating oxidative stress, inflammation and matrix degradation via the TLR4/Syk/NF‐κB pathway.

Potential roles of lncRNA-Cox2 and EGR1 in regulating epidural fibrosis following laminectomy.

Epidural fibrosis, one of the common complications after spinal surgery, seriously affects the surgical decompression effect. Effectively inhibiting the fibrous tissue hyperplasia is pivotal to reduce the scar adhesion. Previous studies showed that early growth response 1 (EGR1) is associated with the fibroblast reactivity induced by transforming growth factor-beta (TGF-β) and plays a vital regulatory role in scar formation; however, the upstream targets and mechanisms still remain unclear. In this work, it was found that the level of long non-coding ribonucleic acid (lncRNA)-cyclooxygenase-2 (COX2) was significantly negatively correlated with EGR1 expression and the severity of the scar. Therefore, it was conjectured that lncRNA-COX2 may decrease fibroplasia and scar formation by negatively regulating EGR1. TGF-β was used to activate the embryonic and adult rat fibroblasts. Rats underwent laminectomy to establish the epidural fibrosis model. The changes in the levels of fibroplasia-related genes were measured and analyzed through messenger RNA (mRNA), lncRNA, and micro RNA expression profile chips. Quantitative Reverse Transcription-Polymerase Chain Reaction (qRT-PCR) was applied to determine the levels of EGR1 and lncRNA-COX2, and Western blotting was adopted to detect the content of EGR1, collagen I (Col-1), Col-3, and alpha-smooth muscle actin (α-SMA). The scar formation was reflected by hematoxylin and eosin (HE) staining and Masson staining, and the expression level of α-SMA in the scar tissues was measured via immunohistochemistry. Finally, micro-magnetic resonance imaging (MRI) was utilized to examine the different degrees of epidural fibroplasia. It was found that the reactivity of embryonic rat fibroblasts to the TGF-β stimulation was different from that of adult rat fibroblasts. LncRNA-COX2 was highly expressed in the embryonic rat fibroblasts, but lowly expressed in the adult rat fibroblasts, which had negative correlations with the EGR1 level in embryonic and adult rat fibroblasts. In addition, it was revealed that the expression of EGR1 in the adult rat fibroblasts was remarkably higher than that in the embryonic rat fibroblasts after the activation with TGF-β. Meanwhile, the level of lncRNA-COX2 was lowered after the activation, especially in the adult rat fibroblasts. It was discovered in the in-vivo model that the degree of fibroplasia was positively associated with EGR1 level and negatively correlated with lncRNA-COX2 level. The results of this research elucidated that the down-regulation of lncRNA-COX2 is involved in the epidural scar formation and related to the elevated EGR1 level which regulates the activation of fibroblasts and secretion of massive extracellular matrixes, suggesting that lncRNA-COX2 may modulate the role of fibroblasts in scar formation as an upstream action target of EGR1.

Establishment and Imaging Studies of Human Lung Cancer-Associated Brain Metastasis Animal Models

Background: Lung cancer is one of the malignant tumors with fast increase in morbidity and mortality, and great threat to human health and life. Methods: Animal models (n = 5) were performed by injecting 1 × 106 A549 cells in 0.1 mL phosphate buffer saline into nude mice through the left ventricle. Body weight of animals was measured every 3 days, and changes in the appearance and behavior were observed. Brain magnetic resonance imaging of 5 animals were performed using T1, T1 enhancement and T2 scan at the 4th, 6th, and 7th weeks after injected with tumor cells. Animals (n = 5) were sacrificed after the last magnetic resonance scan, and brain slices of the animals were prepared to conduct hematoxylin-eosin staining. Results: At the 4th weeks after inoculation of tumor cells, there was no obvious change in the appearance and behavior of animals and there were no obvious tumor metastases in the brains from brain magnetic resonance scan. At the 6th weeks, body weight of all animals (n = 5), one of which appeared paralysis in hind limb, decreased obviously, and results from MR scans showed there were tumor metastases in the brains of all animals. Results from brain magnetic resonance scan images of one animal at 4th, 6th, and 7th weeks showed tumor metastases appeared in the animal's brain and gradually grew bigger. Result from hematoxylin-eosin staining of brain slices showed multiple tumor metastases, consistent with the results of magnetic resonance imaging. Conclusions: Human lung cancer-associated brain metastasis animal models was successfully established, and micro-magnetic resonance imaging is a sensitive, accurate and non-invasive method for the detection of lung cancer brain metastases in mice through this study.

Biomechanical properties of the repaired and non-repaired rat supraspinatus tendon in the acute postoperative period

ABSTRACTPurpose: The rat rotator cuff (RC) model is used to study RC pathology and potential treatment; however, native scar-mediated healing allows the rat RC to recover at 4–6 weeks but little is known about acute healing. This study characterized the properties of the repaired and non-repaired rat RC following surgical detachment. Materials and Methods: Forty-eight rats underwent surgical RC detachment and received surgical repair (Repair) or left unrepaired (Defect) to either 12 or 19 days. Healthy controls were obtained from contralateral limbs. Biomechanical properties were assessed using stress relaxation and failure testing and mechanical modeling performed using quasilinear viscoelastic (QLV) and structurally based elastic models. Histology and micro-magnetic resonance imaging were used to qualitatively grade tendon-to-bone healing. Results: Repair and Defect exhibited significantly inferior mechanical properties compared to Healthy at both time points. Repair had significant increases in peak, equilibrium, and ultimate stress, modulus, and stiffness and significant decreases in cross-sectional area, % relaxation, and QLV constant “C” between 12 and 19 days, whereas Defect showed no change. Conclusions: This study demonstrates acute differences in mechanical properties of the rat supraspinatus tendon in the presence and absence of surgical repair. Understanding the longitudinal recovery of mechanical properties can facilitate more accurate characterization of RC pathology or future treatments.

Micro-scale assessment of the postoperative effect of anterior cruciate ligament reconstruction preclinical study using a 7.1T micro-magnetic resonance imaging.

High-field micro-magnetic resonance imaging (MRI) scanning may provide additional information for quantitative analysis of graft bone healing processes, thus serving as a promising supplementary method in graft and bone healing evaluation following anterior cruciate ligament reconstruction (ACLR) surgery during preclinical studies. The present study included 12 New Zealand white rabbits that underwent ACLR with polyethylene terephthalate (PET) ligament. At 4, 8, and 16 weeks following surgery, 4 rabbits were euthanized and knee joint samples were harvested for a 7.1T micro-magnetic resonance imaging (MRI) scan. The graft bone tunnel diameter and signal noise ratio (SNR) at the region of interest (ROI) were measured. Hematoxylin-eosin staining was performed at each time point to verify the graft bone healing process in histology. The bone tunnel diameter at the graft tunnel interface decreased over time in both femoral and tibial parts. Notably, the tunnel size was smaller than the diameter of the drilling Kirschner wire that was used to observe the femoral part and proximal site of the tibial part at 16 weeks following surgery. SNR research demonstrated that both the femoral and tibial part PET ligaments selected in the ROI exhibited a marked increase in SNR from the initial 4-week results. The micro-MRI result was consistent with that of histological analysis. Micro-MRI scanning was applied in an animal model that underwent ACL reconstruction surgery with PET ligament, and it was determined that micro-MRI is promising in quantitatively observing graft bone healing processes directly with a focus on graft tunnel distances and SNRs.

Micro-imaging of Brain Cancer Radiation Therapy Using Phase-contrast Computed Tomography

Experimental neuroimaging provides a wide range of methods for the visualization of brain anatomic morphology down to subcellular detail. Still, each technique-specific detection mechanism presents compromises among the achievable field-of-view size, spatial resolution, and nervous tissue sensitivity, leading to partial sample coverage, unresolved morphologic structures, or sparse labeling of neuronal populations and often also to obligatory sample dissection or other sample invasive manipulations. X-ray phase-contrast imaging computed tomography (PCI-CT) is an experimental imaging method that simultaneously provides micrometric spatial resolution, high soft-tissue sensitivity, and exvivo full organ rodent brain coverage without any need for sample dissection, staining or labeling, or contrast agent injection. In the present study, we explored the benefits and limitations of PCI-CT use for invitro imaging of normal and cancerous brain neuromorphology after invivo treatment with synchrotron-generated x-ray microbeam radiation therapy (MRT), a spatially fractionated experimental high-dose radiosurgery. The goals were visualization of the MRT effects on nervous tissue and a qualitative comparison of the results to the histologic and high-field magnetic resonance imaging findings. MRT was administered invivo to the brain of both healthy and cancer-bearing rats. At 45days after treatment, the brain was dissected out and imaged exvivo using propagation-based PCI-CT. PCI-CT visualizes the brain anatomy and microvasculature in 3 dimensions and distinguishes cancerous tissue morphology, necrosis, and intratumor accumulation of iron and calcium deposits. Moreover, PCI-CT detects the effects of MRT throughout the treatment target areas (eg, the formation of micrometer-thick radiation-induced tissue ablation). The observed neurostructures were confirmed by histologic and immunohistochemistry examination and related to the micro-magnetic resonance imaging data. PCI-CT enabled a unique 3D neuroimaging approach for exvivo studies on small animal models in that it concurrently delivers high-resolution insight of local brain tissue morphology in both normal and cancerous micro-milieu, localizes radiosurgical damage, and highlights the deep microvasculature. This method could assist experimental small animal neurology studies in the postmortem evaluation of neuropathology or treatment effects.

A rapid micro-magnetic resonance imaging scanning for three-dimensional reconstruction of peripheral nerve fascicles.

The most common methods for three-dimensional reconstruction of peripheral nerve fascicles include histological and radiology techniques. Histological techniques have many drawbacks including an enormous manual workload and poor image registration. Micro-magnetic resonance imaging (Micro-MRI), an emerging radiology technique, has been used to report results in the brain, liver and tumor tissues. However, micro-MRI usage for obtaining intraneural structures has not been reported. The aim of this study was to present a new imaging method for three-dimensional reconstruction of peripheral nerve fascicles by 1T micro-MRI. Freshly harvested sciatic nerve samples from an amputated limb were divided into four groups. Two different scanning conditions (Mannerist Solution/GD-DTPA contrast agent, distilled water) were selected, and both T1 and T2 phases programmed for each scanning condition. Three clinical surgeons evaluated the quality of the images via a standardized scale. Moreover, to analyze deformation of the two-dimensional image, the nerve diameter and total area of the micro-MRI images were compared after hematoxylin-eosin staining. The results show that rapid micro-MRI imaging method can be used for three-dimensional reconstruction of the fascicle structure. Nerve sample immersed in contrast agent (Mannerist Solution/GD-DTPA) and scanned in the T1 phase was the best. Moreover, the nerve sample was scanned freshly and can be recycled for other procedures. MRI images show better stability and smaller deformation compared with histological images. In conclusion, micro-MRI provides a feasible and rapid method for three-dimensional reconstruction of peripheral nerve fascicles, which can clearly show the internal structure of the peripheral nerve.

Correlation of Glioma Proliferation and Hypoxia by Luciferase, Magnetic Resonance, and Positron Emission Tomography Imaging.

Gliomas are the most common type of primary, malignant brain tumor and significantly impact patients, who have a median survival of ~1year depending on mutational background. Novel imaging modalities such as luciferase bioluminescence, micro-magnetic resonance imaging (micro-MRI), micro-computerized tomography (micro-CT), and micro-positron emission tomography (micro-PET) have expanded the portfolio of tools available to study this disease. Hypoxia, a key oncogenic driver of glioma and mechanism of resistance, can be studied in vivo by the concomitant use of noninvasive MRI and PET imaging. We present a protocol involving stereotactic injection of syngenic F98 luciferase-expressing glioma cells generated by our laboratory into Fischer 344 rat brains and imaging using luciferase. In addition, 18-F-fludeoxyglucose, 18F-fluoromisonidazole, and 18F-fluorothymidine PET imaging are compared with quantified luciferase flux. These tools can potentially be used for assessing tumor growth characteristics, hypoxia, mutational effects, and treatment effects.

Real-time quantitative analysis of metabolic flux in live cells using a hyperpolarized micromagnetic resonance spectrometer.

Metabolic reprogramming is widely considered a hallmark of cancer, and understanding metabolic dynamics described by the conversion rates or "fluxes" of metabolites can shed light onto biological processes of tumorigenesis and response to therapy. For real-time analysis of metabolic flux in intact cells or organisms, magnetic resonance (MR) spectroscopy and imaging methods have been developed in conjunction with hyperpolarization of nuclear spins. These approaches enable noninvasive monitoring of tumor progression and treatment efficacy and are being tested in multiple clinical trials. However, because of their limited sensitivity, these methods require a larger number of cells, on the order of 107, which is impractical for analyzing scant target cells or mass-limited samples. We present a new technology platform, a hyperpolarized micromagnetic resonance spectrometer (HMRS), that achieves real-time, 103-fold more sensitive metabolic analysis on live cells. This platform enables quantification of the metabolic flux in a wide range of cell types, including leukemia stem cells, without significant changes in viability, which allows downstream molecular analyses in tandem. It also enables rapid assessment of metabolic changes by a given drug, which may direct therapeutic choices in patients. We further advanced this platform for high-throughput analysis of hyperpolarized molecules by integrating a three-dimensionally printed microfluidic system. The HMRS platform holds promise as a sensitive method for studying metabolic dynamics in mass-limited samples, including primary cancer cells, providing novel therapeutic targets and an enhanced understanding of cellular metabolism.

Micro-MREによるゼラチンゲルとブタ肝臓の動的粘弾性計測

This study aimed to measure a viscoelastic property of gelatin gels and porcine liver by the magnetic resonance elastography using micro-magnetic resonance imaging (micro-MRE). In the experiments, gelatin gel specimens (90 × 70 × 50 mm) made of gelatin solution with 5, 7, 10, 12, and 15 wt% concentration were examined under excitation with longitudinal waves in frequency of 50-250 Hz and amplitude of 0.5 mm. The viscoelastic modulus was obtained as storage shear modulus G’ and loss shear modulus G”. As a result, G’ values increased with the concentration and the excitation frequency. G” value was much smaller than G’. Double-layer specimens composed of 5 and 15 wt% gelatin gels were also examined. The average of G’ in each concentration gel in the double-layer specimens showed no significant difference from the single-material specimens with the same concentration. Furthermore, a porcine liver specimen (150 × 50 × 30 mm) were examined; however, the specimen were not vibrated and the displacement distribution in the specimen was not observed. When porcine liver specimens were embedded in the 15 wt% gel (70 × 70 × 50 mm), the specimens were vibrated deeply and G’ and G” of the liver and gel regions were obtained. As a result, G’ of the gel region was almost the same as the value of the gel specimens. G’ of the liver region increased with the excitation frequency as well as the gel specimens. The viscoelastic modulus of the porcine liver could be measured by embedding it inside gelatin gel using the micro-MRE system. This study demonstrated the application of the MRE system as the dynamic viscoelasticity measurements of gelatin gel and liver specimen.

Free water in bean seeds: The imbibition process observed by micro-magnetic resonance imaging

Water uptake by dry Lima beans (Phaseolus limensis L.) was traced using 1H micro-magnetic resonance imaging. The studies are performed using two-dimensional longitudinal images. Channels through which water comes in an imbibing bean seed are determined; the water distribution inside the seed is shown to be heterogeneous.

Optical coherence tomography for embryonic imaging: a review.

Embryogenesis is a highly complex and dynamic process, and its visualization is crucial for understanding basic physiological processes during development and for identifying and assessing possible defects, malformations, and diseases. While traditional imaging modalities, such as ultrasound biomicroscopy, micro-magnetic resonance imaging, and micro-computed tomography, have long been adapted for embryonic imaging, these techniques generally have limitations in their speed, spatial resolution, and contrast to capture processes such as cardiodynamics during embryogenesis. Optical coherence tomography (OCT) is a noninvasive imaging modality with micrometer-scale spatial resolution and imaging depth up to a few millimeters in tissue. OCT has bridged the gap between ultrahigh resolution imaging techniques with limited imaging depth like confocal microscopy and modalities, such as ultrasound sonography, which have deeper penetration but poorer spatial resolution. Moreover, the noninvasive nature of OCT has enabled live imaging of embryos without any external contrast agents. We review how OCT has been utilized to study developing embryos and also discuss advances in techniques used in conjunction with OCT to understand embryonic development.

Water entry for the black locust (Robinia pseudoacacia L.) seeds observed by dedicated micro-magnetic resonance imaging.

Water entry at germination for black locust (Robinia pseudoacacia L.) seeds which are known as hard seeds with impermeable seed coat to water, was examined using micro-magnetic resonance imaging (MRI). The MRI apparatus equipped with a low-field (1 T; Tesla) permanent magnet was used, which is open access, easy maintenance, operable and transportable. The excellent point of the apparatus is that T 1-enhancement of water signals absorbed in dry seeds against steeping free water is stronger than the apparatuses with high-field superconducting magnets, which enabled clear detection of water entry. Water hardly penetrated into the seeds for more than 8h but approximately 60% of seeds germinated by incubating on wet filter papers for several days. Hot water treatments above 75°C for 3min effectively induced water gap; scarification was 70% at 100°C and 75°C, declined to 15% at 50°C and decreased further at room temperature. Water entered into the scarified seeds exclusively through the lens, spread along the dorsal side of the seeds and reached the hypocotyl, whereas water migrated slowly through hilum side to radicle within 3h.