Synthesis and Properties of 2'-OMe-RNAs Modified with Cross-Linkable 7-Deazaguanosine Derivatives.

Cross-linkable 7-deaza-6-vinylguanosine (ADVP) and 7-propynyl-7-deaza-6-vinylguanosine (ADpVP) derivatives were synthesized and successfully incorporated into 2'-OMe-RNA oligonucleotides by solid-phase oligonucleotide synthesis. Analysis of their cross-link properties revealed that the 7-propynyl substituent on ADpVP induces a significant enhancement of the cross-link kinetics of the proximal 6-vinyl group to the complementary uracil base in the target RNA compared to that of ADVP. In addition, the 2'-OMe-RNA oligonucleotide containing ADpVP exhibited a higher antisense effect on luciferase production in the cell lysate than that of ADVP. These results suggested that the 7-substituted 7-deaza-6-vinylguanosine derivatives can be used as potent cross-linkers to target mRNA inside of cells.

Bluish-White Luminescence in Rare-Earth-Free Vanadate Garnet Phosphors: Structural Characterization of LiCa3MV3O12 (M = Zn and Mg).

Extensive attention has been focused toward studies on inexpensive and rare-earth-free garnet-structure vanadate phosphors, which do not have a low optical absorption due to the luminescence color being easily controlled by its high composition flexibility. However, bluish emission phosphors with a high quantum efficiency have not been found until now. In this study, we successfully discovered bluish-white emitting, garnet structure-based LiCa3MV3O12 (M = Zn and Mg) phosphors with a high quantum efficiency, and the detailed crystal structure was refined by the Rietveld analysis technique. These phosphors exhibit a broad-band emission spectra peak at 481 nm under near UV-light excitation at 341 nm, indicating no clear difference in the emission and excitation spectra. A very compact tetrahedral [VO4] unit is observed in the LiCa3MV3O12 (M = Zn and Mg) phosphors, which is not seen in other conventional garnet compounds, and generates a bluish-white emission. In addition, these phosphors exhibit high quantum efficiencies of 40.1% (M = Zn) and 44.0% (M = Mg), respectively. Therefore, these vanadate garnet phosphors can provide a new blue color source for LED devices.

Principle and basic property of the sequential flow pump.

In the emergency care field, early treatment of acute heart or respiratory failure has been a global concern. In severe cases, patients are frequently required to be on an extracorporeal membrane oxygenator (ECMO) life support. To make the ECMO system more compact and portable, we proposed a sequential flow-type centrifugal pump named the sequential flow pump (SFP). In this study, principle and basic properties of this novel blood pump were examined by computational fluid dynamic (CFD) analysis and an experimental model. In the SFP, fluid is given centrifugal force sequentially twice with a single closed impeller. This sequential pressurization mechanism enables high-pressure output without high impeller speed. To realize easy integration of a blood pump with an artificial lung, the inlet and outlet ports are located at lateral side and center of the pump, respectively, which is the reverse configuration of conventional centrifugal pumps. The computational model was composed for CFD analysis and the experimental model was developed for the experiment of the actual pump. For both models, dimension of the impeller and volute was designed to be equal. In the CFD analysis, the SFP could generate higher performance than the single pressurization model with the same rotational speed of the impeller. Basic property of the experimental model was very similar to that of the computational model. The results showed the possibility that the SFP would be more suitable for the compact ECMO system than conventional centrifugal pumps.

Appropriate control time constant in relation to characteristics of the baroreflex vascular system in 1/R control of the total artificial heart.

1/R control is a physiological control method of the total artificial heart (TAH) with which long-term survival was obtained with animal experiments. However, 1/R control occasionally diverged in the undulation pump TAH (UPTAH) animal experiment. To improve the control stability of the 1/R control, appropriate control time constant in relation to characteristics of the baroreflex vascular system was investigated with frequency analysis and numerical simulation. In the frequency analysis, data of five goats in which the UPTAH was implanted were analyzed with first Fourier transform technique to examine the vasomotion frequency. The numerical simulation was carried out repeatedly changing baroreflex parameters and control time constant using the elements-expanded Windkessel model. Results of the frequency analysis showed that the 1/R control tended to diverge when very low frequency band that was an indication of the vasomotion frequency was relative high. In numerical simulation, divergence of the 1/R control could be reproduced and the boundary curves between the divergence and convergence of the 1/R control varied depending on the control time constant. These results suggested that the 1/R control tended to be unstable when the TAH recipient had high reflex speed in the baroreflex vascular system. Therefore, the control time constant should be adjusted appropriately with the individual vasomotion frequency.

Histopathology Image Analysis in Two Long-Term Animal Experiments with Helical Flow Total Artificial Heart.

Histopathological analysis can provide important information in long-term experiments with total artificial heart (TAH). Recently, a new type of blood pump, the helical flow total artificial heart (HF-TAH) was developed. This study aimed to investigate the changes in selected vital organs in animal experiments with implanted HF-TAH. Samples from lung, liver, and kidneys from two female goats (No. 1301 and No. 1304) with implanted HF-TAH were analyzed. Tissue samples were fixed in 10% formaldehyde and 4 µm thick transverse sections were stained with hematoxylin-eosin (HE). Additional staining was done for detection of connective tissue (Masson-Goldner stain) and for detection of iron (hemosiderin) deposits (Perls stain). Sections were scanned at 100× and 500× magnification with a light microscope. Experiment no. 1301 survived 100 days (cause of termination was heavy damage of the right pump); experimental goat no.1304 survived 68 days and was sacrificed due to severe right hydrodynamic bearing malfunction. Histopathological analysis of liver samples proved signs of chronic venostasis with limited focal necrotic zones. Dilated tubules, proteinaceous material in tubular lumen, and hemosiderin deposits were detected in kidney samples. Contamination of the organs by embolized micro-particles was suspected at the autopsy after discovery of visible damage (scratches) of the pump impeller surface (made from titanium alloy) in both experiments. Sporadic deposits of foreign micro-particles (presumably titanium) were observed in most of the analyzed parenchymal organs. However, the described deposits were not in direct connection with inflammatory reactions in the analyzed tissues. Histopathological analysis showed the presence of minimal contamination of the lung, kidney, and liver tissue samples by foreign material (titanium very likely). The analysis showed only limited pathological changes, especially in liver and kidneys, which might be attributed to the influence of artificial perfusion often observed in chronic TAH experiments.

Viscosity-adjusted estimation of pressure head and pump flow with quasi-pulsatile modulation of rotary blood pump for a total artificial heart.

Estimation of pressure and flow has been an important subject for developing implantable artificial hearts. To realize real-time viscosity-adjusted estimation of pressure head and pump flow for a total artificial heart, we propose the table estimation method with quasi-pulsatile modulation of rotary blood pump in which systolic high flow and diastolic low flow phased are generated. The table estimation method utilizes three kinds of tables: viscosity, pressure and flow tables. Viscosity is estimated from the characteristic that differential value in motor speed between systolic and diastolic phases varies depending on viscosity. Potential of this estimation method was investigated using mock circulation system. Glycerin solution diluted with salty water was used to adjust viscosity of fluid. In verification of this method using continuous flow data, fairly good estimation could be possible when differential pulse width modulation (PWM) value of the motor between systolic and diastolic phases was high. In estimation under quasi-pulsatile condition, inertia correction was provided and fairly good estimation was possible when the differential PWM value was high, which was not different from the verification results using continuous flow data. In the experiment of real-time estimation applying moving average method to the estimated viscosity, fair estimation could be possible when the differential PWM value was high, showing that real-time viscosity-adjusted estimation of pressure head and pump flow would be possible with this novel estimation method when the differential PWM value would be set high.

Enantioselective Synthesis of Silacyclopentanes.

A variety of functionalized silacyclopentanes were synthesized by highly enantioselective ß-eliminations of silacyclopentene oxides followed by stereospecific transformations. The reaction mechanism of the ß-elimination was elucidated by DFT calculations. An in vitro biological assay with an oxy-functionalized silacyclopentane showed substantial binding to a serotonin receptor protein.

Animal Experiments of the Helical Flow Total Artificial Heart.

Severe cardiac failure patients require a total artificial heart (TAH) to save life. To realize a TAH that can fit a body of small stature and has high performance, high durability, good anatomical fitting, good blood compatibility, and physiological control, we have been developing the helical flow TAH (HFTAH) with two helical flow pumps with hydrodynamic levitation impeller. Animal experiments of the HFTAH were conducted to perform in vivo studies. The HFTAH was implanted in 13 adult female goats weighing 45.0-64.0 kg. After surgery, neither anti-coagulant nor anti-platelet medication was given systemically. The HFTAH was usually driven with a quasi-pulsatile mode. The 1/R control or ΔP control was applied to control the circulation. The ΔP control is a new method using simplified equation of the 1/R control. The HFTAH could be implanted in all goats with good anatomical fitting. Two goats survived for a long time (100 and 68 days). Major causes of termination were device failure and surgical complications. In the device failure, trouble with hydrodynamic bearing was conspicuous. In the two long-term survived goats, experiments were terminated with bearing instability that was probably caused by the suction effect. In these goats, hemolysis occurred on postoperative day 88 and 44, which was considered to be relevant to the bearing trouble. Thrombus was found at the broken right bearing of the 100-day survived goat. However, antithrombogenicity of the pump is expected to be good unless bearing trouble occurs. In two long-term survived goats, the 1/R control or ΔP control worked appropriately to prevent the elevation of right atrial pressure. In both goats, hemodynamic parameters changed with the condition of the animals, liver and kidney functions remained almost normal except when recovering from surgery and during hemolysis, and total protein recovered 2 weeks after surgery. Although instability of the hydrodynamic bearing should be improved, performance of the HFTAH with physiological control could be demonstrated.

Hydrodynamic characteristics of the helical flow pump.

The helical flow pump (HFP) was invented to be an ideal pump for developing the TAH and the helical flow TAH (HFTAH) using two HFPs has been developed. However, since the HFP is quite a new pump, hydrodynamic characteristics inside the pump are not clarified. To analyze hydrodynamic characteristics of the HFP, flow visualization study using the particle image velocimetry and computational fluid dynamics analysis were performed. The experimental and computational models were developed to simulate the left HFP of the HFTAH and distributions of flow velocity vectors, shear stress and pressure inside the pump were examined. In distribution of flow velocity vectors, the vortexes in the vane were observed, which indicated that the HFP has a novel and quite unique working principle in which centrifugal force rotates the fluid in the helical volutes and the fluid is transferred from the inlet to the outlet helical volutes according to the helical structure. In distribution of shear stress, the highest shear stress that was considered to be occurred by the shunt flow across the impeller was found around the entrance of the inlet helical volute. However, it was not so high to cause hemolysis. This shunt flow is thought to be improved by redesigning the inlet and outlet helical volutes. In distribution of pressure, negative pressure was found near the entrance of the inlet helical volute. However, it was not high. Negative pressure is thought to be reduced with an improvement in the design of the impeller or the vane shape.

Computational fluid dynamics analysis of the pump parameters in the helical flow pump.

The helical flow pump (HFP) was invented to develop a total artificial heart at the University of Tokyo in 2005. The HFP consists of the multi-vane impeller involving rotor magnets, a motor stator and pump housing having double-helical volutes. To investigate the characteristics of the HFP, computational fluid dynamics analysis was performed. Validation of the computational model was performed with the data of the actual pump. A control computational model in which the vane area corresponded approximately to that of the actual pump was designed for the parametric study. The parametric study was performed varying the vane height, vane width and helical volute pitch. When the vane height was varied from 0.5 to 1.5 times that of the control computational model, the H-Q (pressure head vs. flow) and efficiency curves were translated in parallel with the vane height. When the vane height was two and three times that of the control computational model, the profile of these curves changed. From the results, the best proportion for the vane was considered to be a vane height between 1.5 and 2 times the vane width. The effect of vane width was not very strong compared to that of the vane height. A similar tendency in vane height was observed by varying the helical volute pitch. The best helical volute-pitch size is considered to be between 1.5 and 2 times the vane width. Although further study is necessary to determine the best values for these parameters, the characteristics of the pump parameters in the HFP could be approximately clarified.

Concept of left atrial pressure estimation using its pulsatile amplitude in the helical flow total artificial heart.

The total artificial heart (TAH) requires physiological control to respond to the metabolic demand of the body. To date, 1/R control is a single physiological control method that can control venous pressure. To realize an implantable 1/R control system, we are developing a new pressure measuring method using absolute pressure sensor. To find a method for absolute pressure sensor, which went well without calibration, concept of left atrial pressure (LAP) estimation using its pulsatile amplitude was proposed. Its possibility was investigated with two long-term survived goats whose hearts were replaced with the helical flow TAHs. In manual control condition, there existed a positive relation between mean LAP (mLAP) and normalized pulsatile amplitude (NPA). Percent systole revealed not to affect the relationship between mLAP and NPA. Dispersion was observed between different pulse rates. As for cardiac output difference (QLD) that is the difference of flow rate between systolic and diastolic phases, similar results were obtained except in low QLDs. In the 1/R control condition, relatively high correlation between mLAP and NPA could be obtained. In estimation of mLAP using the correlating function of individual goat, fairly good correlation was obtained between measured mLAP and estimated mLAP. Despite that further studies are necessary, it was demonstrated that the concept of the LAP estimation could be possible.

Cathode active materials using rare metals recovered from waste lithium-ion batteries: A review.

Large-scale lithium-ion batteries (LIBs) are overtaking as power sources for electric vehicles and grid-scale energy-storage systems for renewable sources. Accordingly, large amounts of LIBs are expected to be discarded in the near future. Recycling technologies for waste LIBs, particularly for valuable rare metals (Li, Co, and Ni) used in cathode active materials, need to be developed to construct continuous LIB supply chains. Various recovery methodologies, such as pyrometallurgy, hydrometallurgy, and direct recycling, as well as their advantages, disadvantages, and technical features, are briefly introduced. We review the electrochemical performances of these cathode active materials based on recycled rare metals from LIB waste. Moreover, the physicochemical properties and electrochemical performance of the cathode active materials with impurities incorporated during recycling, which have high academic significance, are outlined. In hydrometallurgy-based LIB recycling, the complete removal of impurities in cathode active materials is not realistic for the mass and sustainable production of LIBs; thus, optimal control of the impurity levels is of significance. Meanwhile, the studies on the direct recycling of LIB showed the necessity of almost complete impurity removal and restoration of physicochemical properties in cathode active materials. This review provides a survey of the technological outlook of reusing cathode active materials from waste LIBs.

VP1 of human and murine noroviruses recognizes glycolipid sulfatide via the P domain.

Noroviruses are a prevalent cause of human viral gastroenteritis, yet the precise mechanisms underlying their infection cycle, particularly their interactions with and entry into cells, remain poorly understood. Human norovirus (HuNoV) primarily targets human small intestinal epithelial cells, within which 3-O-sulfogalactosylceramide (sulfatide) ranks among the most abundant glycosphingolipids (GSLs). While sulfatide involvement in the binding and infection mechanism of several viruses has been documented, its interaction with noroviruses remains underexplored. This study investigated whether noroviruses interact with sulfatide. We found that the recombinant viral capsid protein VP1 of HuNoV (genogroups I and II) and murine norovirus (genogroup V) exhibited robust binding to sulfatide compared with other tested GSLs using enzyme-linked immunosorbent assay, thin-layer chromatography binding assay and real-time quantitative reverse transcription polymerase chain reaction binding assay. VP1 also bound 3-O-sulfated lactosylceramide, which shares the 3-O-sulfated galactose moiety with sulfatide. However, both VP1 and its P domain, identified as the sulfatide-binding domain, exhibited limited binding to structural analogues of sulfatide and other sulfated compounds. These findings suggest a specific recognition of the 3-O-sulfated galactose moiety. Notably, we found that sulfatide is a novel binding target for norovirus particles. Overall, our findings reveal a previously unknown norovirus-sulfatide interaction, proposing sulfatide as a potential candidate for norovirus infection receptors.

Simulation of the aortic valve deformation by considering blood flow reflection.

We have tried to simulate the aortic valve deformation by considering the reflection of blood flow. The aortic valve opens and closes according to blood flow caused by pressure difference between the heart and the aorta. The aortic valve is elastic body while blood is fluid so that two different types of methods are usually used for the simulation; however, it is difficult to calculate collision detection and force between two different types of models. Then, in this paper, both materials are modeled with particles so that collision detection and force between two different types of models can be easily calculated. In addition, by considering the reflection of blood flow at the end of blood vessel, we have succeeded to simulate the deformation of the aortic valve and found that blood flows differently depending on the length of the aortic valve.

Fluid shear stress induces differentiation of circulating phenotype endothelial progenitor cells.

Endothelial progenitor cells (EPCs) are mobilized from bone marrow to peripheral blood, and contribute to angiogenesis in tissue. In the process, EPCs are exposed to shear stress generated by blood flow and tissue fluid flow. Our previous study showed that shear stress induces differentiation of mature EPCs in adhesive phenotype into mature endothelial cells and, moreover, arterial endothelial cells. In this study we investigated whether immature EPCs in a circulating phenotype differentiate into mature EPCs in response to shear stress. When floating-circulating phenotype EPCs derived from ex vivo expanded human cord blood were exposed to controlled levels of shear stress in a flow-loading device, the bioactivities of adhesion, migration, proliferation, antiapoptosis, tube formation, and differentiated type of EPC colony formation increased. The surface protein expression rate of the endothelial markers VEGF receptor 1 (VEGF-R1) and -2 (VEGF-R2), VE-cadherin, Tie2, VCAM1, integrin α(v)/ß(3), and E-selectin increased in shear-stressed EPCs. The VEGF-R1, VEGF-R2, VE-cadherin, and Tie2 protein increases were dependent on the magnitude of shear stress. The mRNA levels of VEGF-R1, VEGF-R2, VE-cadherin, Tie2, endothelial nitric oxide synthase, matrix metalloproteinase 9, and VEGF increased in shear-stressed EPCs. Inhibitor analysis showed that the phosphoinositide 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) signal transduction pathway is a potent activator of adhesion, proliferation, tube formation, and differentiation in response to shear stress. Western blot analysis revealed that shear stress activated the VEGF-R2 phosphorylation in a ligand-independent manner. These results indicate that shear stress increases differentiation, adhesion, migration, proliferation, antiapoptosis, and vasculogenesis of circulating phenotype EPCs by activation of VEGF-R2 and the PI3K/Akt/mTOR signal transduction pathway.

A single starfish Aurora kinase performs the combined functions of Aurora-A and Aurora-B in human cells.

Aurora, an essential mitotic kinase, is highly conserved during evolution. Most vertebrates have at least two Aurora kinases, Aurora-A and Aurora-B, which have distinct functions in the centrosome-spindle and inner centromere-midbody, respectively. However, some non-vertebrate deuterostomes have only a single Aurora. It remains to be verified whether the single Aurora performs the same functions as vertebrate Auroras A and B combined. We have isolated a cDNA of a single Aurora (ApAurora) from the echinoderm starfish, Asterina pectinifera, and show that ApAurora displays most features of both Aurora-A and Aurora-B in starfish oocytes and early embryos. Furthermore, ApAurora that is stably expressed in HeLa cells can substitute for both human Aurora-A and Aurora-B when either is reduced by RNAi. A single ApAurora thus has properties of both Aurora-A and Aurora-B in starfish eggs and HeLa cells. Together with phylogenetic analysis indicating that ApAurora forms a clade with all types of vertebrate Auroras and single Auroras of non-vertebrate deuterostomes, our observations support the idea that the single Aurora found in non-vertebrate deuterostomes represents the ancestor that gave rise to various types of vertebrate Auroras. This study thus provides functional evidence for phylogenetic considerations.

Development of normal-suction boundary control method based on inflow cannula pressure waveform for the undulation pump ventricular assist device.

It is desirable to obtain the maximum assist without suction in ventricular assist devices (VADs). However, high driving power of a VAD may cause severe ventricle suction that can induce arrhythmia, hemolysis, and pump damage. In this report, an appropriate VAD driving level that maximizes the assist effect without severe systolic suction was explored. The target driving level was set at the boundary between low driving power without suction and high driving power with frequent suction. In the boundary range, intermittent mild suction may occur. Driving power was regulated by the suction occurrence. The normal-suction boundary control method was evaluated in a female goat implanted with an undulation pump ventricular assist device (UPVAD). The UPVAD was driven in a semipulsatile mode with heartbeat synchronization control. Systolic driving power was adjusted using a normal-suction boundary control method developed for this study. We confirmed that driving power could be maintained in the boundary range. Occurrences of suction were evaluated using the suction ratio. We defined this ratio as the number of suction occurrences divided by the number of heartbeats. The suction ratio decreased by 70% when the normal-suction boundary control method was used.

The helical flow pump with a hydrodynamic levitation impeller.

The helical flow pump (HFP) is a novel rotary blood pump invented for developing a total artificial heart (TAH). The HFP with a hydrodynamic levitation impeller, which consists of a multi-vane impeller involving rotor magnets, stator coils at the core position, and double helical-volute pump housing, was developed. Between the stator and impeller, a hydrodynamic bearing is formed. Since the helical volutes are formed at both sides of the impeller, blood flows with a helical flow pattern inside the pump. The developed HFP showed maximum output of 19 l/min against 100 mmHg of pressure head and 11 % maximum efficiency. The profile of the H-Q (pressure head vs. flow) curve was similar to that of the undulation pump. Hydrodynamic levitation of the impeller was possible with higher than 1,000 rpm rotation speed. The normalized index of the hemolysis ratio of the HFP to centrifugal pump (BPX-80) was from 2.61 to 8.07 depending on the design of the bearing. The HFP was implanted in two goats with a left ventricular bypass method. After surgery, hemolysis occurred in both goats. The hemolysis ceased on postoperative days 14 and 9, respectively. In the first experiment, no thrombus was found in the pump after 203 days of pumping. In the second experiment, a white thrombus was found in the pump after 23 days of pumping. While further research and development are necessary, we are expecting to develop an excellent TAH with the HFP.

Role of SiOx in rice-husk-derived anodes for Li-ion batteries.

The present study investigated the role of SiOx in a rice-husk-derived C/SiOx anode on the rate and cycling performance of a Li-ion battery. C/SiOx active materials with different SiOx contents (45, 24, and 5 mass%) were prepared from rice husk by heat treatment and immersion in NaOH solution. The C and SiOx specific capacities were 375 and 475 mAh g-1, respectively. A stable anodic operation was achieved by pre-lithiating the C/SiOx anode. Full-cells consisting of this anode and a Li(Ni0.5Co0.2Mn0.3)O2 cathode displayed high initial Coulombic efficiency (~ 85%) and high discharge specific capacity, indicating the maximum performance of the cathode (~ 150 mAh g-1). At increased current density, the higher the SiOx content, the higher the specific capacity retention, suggesting that the time response of the reversible reaction of SiOx with Li ions is faster than that of the C component. The full-cell with the highest SiOx content exhibited the largest decrease in cell specific capacity during the cycle test. The structural decay caused by the volume expansion of SiOx during Li-ion uptake and release degraded the cycling performance. Based on its high production yield and electrochemical benefits, degree of cycling performance degradation, and disadvantages of its removal, SiOx is preferably retained for Li-ion battery anode applications.

Results of animal experiments with the fourth model of the undulation pump total artificial heart.

Animal experiments using a total artificial heart in a goat are not easy to perform. The fourth model of the undulation pump total artificial heart (UPTAH4), which was designed to perform a long-term physiological experiment including pulsatile and nonpulsatile TAH operations with a conductance- and arterial pressure-based control method named 1/R control, was implanted in 31 goats weighing 38.5 to 60.4 kg (average of 46.8 kg). The 1/R control is a physiological flow control method of TAH developed with a conductance (1/R: reciprocal of a resistance) parallel circuit model. The survival periods were from 0.1 to 153 days (average of 14.5 days). The causes of termination were postoperative bleeding in eight goats, respiratory failure in five goats, device failure in 14 goats, dissected aneurysm in two goats, and thrombus in one goat. The thrombus case was the longest surviving goat. The respiratory failure tended to occur when the extracorporeal circulation time was prolonged. Autotransfusion was effective for the prolongation of survival time. The left-right balance control and the suction control were performed successfully in all goats. The 1/R control was performed for a long time in five goats that survived for more than 1 month. With three goats that survived for 48, 52, and 53 days mainly with the pulsatile mode, the 1/R control was stable. With a goat that survived for 73 days, the nonpulsatile mode with the 1/R control could be tested for 3 weeks. With the longest surviving goat that was maintained mainly with the pulsatile mode, the 1/R control was unstable, possibly due to the mismatching of the response time of the control system between the computer and the body. However, liver and kidney functions were almost normal, and the total protein level recovered. Further study to stabilize the 1/R control in the UPTAH is necessary.