Hyperpolarized^(3)He or^(129)Xe diffusion MRI has been demonstrated as a promising technique for the detection of microanatomical changes in chronic obstructive pulmonary disease(COPD).Compared with ^(3)He,^(129)Xe is...Hyperpolarized^(3)He or^(129)Xe diffusion MRI has been demonstrated as a promising technique for the detection of microanatomical changes in chronic obstructive pulmonary disease(COPD).Compared with ^(3)He,^(129)Xe is more available for the potential clinical applications.However,the measurement of^(129)Xe apparent diffusion coefficient(ADC)possesses more challenges due to the relevant low gyromagnetic ratio and spin polarization.In this present study,a singleb value(b=14 s/cm^(2))diffusion-weighted hyperpolarized^(129)Xe MRI sequence was used to image a balloon phantom,healthy rats,and the COPD rats,respectively.All COPD rats were induced by second-hand smoke and lipopolysaccharide(LPS).The lung^(129)XeADCmaps were obtained on a 7 T MRI scanner.The mean lung parenchymal^(129)XeADCswere 0.04422±0.0029 and 0.04234±0.0023 cm^(2)/s(Δ=0.8/1.2 ms)for the COPD rats,which showed significant increasements in comparison with healthy ones(0.0377±0.0023 and 0.0367±0.0013 cm^(2)/s).Furthermore,the correspondingADChistogram of the COPD rats exhibited a broader distribution as compared with the healthy ones.Our experiments demonstrated that the alveolar airspace enlargement in the COPD rats are able to be quantitatively evaluated by hyperpolarized xenon diffusion-weighted MRI.展开更多
Objective To study the effect of ivabradine on hyperpolarization activated cation current in canine pulmonary vein(PY) sleeve cardiomyocytes with atrial fibrillation.Methods Dissociation of PVs yielded single cardiomy...Objective To study the effect of ivabradine on hyperpolarization activated cation current in canine pulmonary vein(PY) sleeve cardiomyocytes with atrial fibrillation.Methods Dissociation of PVs yielded single cardiomyocytes from a Landengorff column without or with pacemaker activity from long-term rapidly atrial pacing (RAP) canines.If current was measured with the whole-cell patch-clamp technique.Results Compared with the control group,the rapidly atrial pacing canine PV cardiomyocytes had spontaneous diastolic depolarization and had larger If densities.Ivabradine (Iva,1 μM),a selective inhibitor of the If current,markedly reduced If currents in the RAP from -2.66±0.4 pA/pF to -1.58±0.1 pA/pF at the test potential of-120 mV (P＜0.01,n=12).Inhibition effect of Iva of If current showed concentration-dependent range from 0.1 to 10.0μM,with IC50 of 2.2 μ M ( 1.8-2.9 μM,95% CL).Furthermore,V1/ of steady-state activated curve was shifted from -84.3±4.9 mV to -106.9±3.4 mV and k value of steady-state activated curve was changed from 12.1+2.6 mV to 9.9±3.4 mV by the application of.1.0 μM Iva ( P＜0.01,n=12).Conclusions Our study revealed that Ivarbadine may significantly decrease If of rapidly atrial pacing pulmonary vein sleeve ceUs with atrial fibdllation.(J Geriatr Cardiol 2008;5:39-42)展开更多
We study the feasibility and safety of human lung hyperpolarized（HP）^（129）Xe magnetic resonance imaging（MRI）.There is no significant change in physiological parameters before and after the examinations of all su...We study the feasibility and safety of human lung hyperpolarized（HP）^（129）Xe magnetic resonance imaging（MRI）.There is no significant change in physiological parameters before and after the examinations of all subjects.Compared with computed tomography, HP^（129）Xe MRI is sensitive to earlier and smaller ventilation defects. The distribution of the HP^（129）Xe MRI signal reflects the pulmonary compliance with the gravity gradient. This is the first application of HP^（129）Xe MRI ventilation imaging in China, and this technology is expected to provide more useful information for clinical practice.展开更多
Hyperpolarization-activated cyclic-nucleotide-gated (HCN) channels in the heart modulate cardiac automaticity via the hyperpolarization-activated cation current ( named Ⅰf, Ⅰh, or Ⅰq). Recent studies have unveiled ...Hyperpolarization-activated cyclic-nucleotide-gated (HCN) channels in the heart modulate cardiac automaticity via the hyperpolarization-activated cation current ( named Ⅰf, Ⅰh, or Ⅰq). Recent studies have unveiled the molecular identity of HCN (HCN1-4) channels. HCN isoforms are unevenly expressed in the heart, even in the sinoatrial node. Features of HCN currents have been characterized in cardiac and other types of cells or in cell lines transfected with the HCN isoforms. The factors modulating Ih and the physiological significance of HCN channels in the heart have been extensively investigated in recent years. The hypothesis for transplanting and/or creating biological pacemakers to replace diseased sinoatrial and/or atrioventricular nodes has been postulated and tested in animal models. Local overexpression of HCN2 channels in the left atrium or in the left conductive bundle branch of the left ventricle via gene delivery induced significant Ⅰh and escape rhythms during vagal stimulation in canines. In addition, implantation of human mesenchymal stem cells with overexpression of HCN2 channels to the canine left ventricular wall was associated with formation of spontaneous escape rhythms of left-sided origin during vagal-stimulation-induced sinus arrest. This preliminary data suggest that the use of HCN channels may hold great promise in,the development of biological pacemakers.展开更多
Abstract Hyperpolarization-activated cyclic-nucleotide-gated ( HCN) channels in the heart modulate cardiac automaticity via the hyperpolarization-activated cation current (named If, Ih, or Iq). Recent studies have unv...Abstract Hyperpolarization-activated cyclic-nucleotide-gated ( HCN) channels in the heart modulate cardiac automaticity via the hyperpolarization-activated cation current (named If, Ih, or Iq). Recent studies have unveiled the molecular identity of HCN (HCN 1-4) channels. HCN isoforms are unevenly expressed in the heart, even in the sinoatrial node. Features of HCN currents have been characterized in cardiac and other types of cells or in cell lines transfected with the HCN isoforms. The factors modulating Ih and the physiological significance of HCN channels in the heart have been extensively investigated in recent years. The hypothesis for transplanting and/or creating biological pacemakers to replace diseased sinoatrial and/or atrioventricular nodes has been postulated and tested in animal models. Local overexpression of HCN2 channels in the left atrium or in the left conductive bundle branch of the left ventricle via gene delivery induced significant Ih and escape rhythms during vagal stimulation in canines. In addition, implantation of human mesenchymal stem cells with overexpression of HCN2 channels to the canine left ventricular wall was associated with formation of spontaneous escape rhythms of left-sided origin during vagal-stimulation-induced sinus arrest. This preliminary data suggest that the use of HCN channels may hold great promise in the development of biological pacemakers.展开更多
NMR hyperpolarization dramatically improves the detection sensitivity of magnetic resonance through the increase in nuclear spin polarization.Because of the sensitivity increase by several orders of magnitude,addition...NMR hyperpolarization dramatically improves the detection sensitivity of magnetic resonance through the increase in nuclear spin polarization.Because of the sensitivity increase by several orders of magnitude,additional applications have been unlocked,including imaging of gases in physiologically relevant conditions.Hyperpolarized ^(129)Xe gas recently received FDA approval as the first inhalable gaseous MRI contrast agent for clinical functional lung imaging of a wide range of pulmonary diseases.However,production and utilization of hyperpolarized ^(129)Xe gas faces a number of translational challenges including the high cost and complexity of contrast agent production and imaging using proton-only(i.e.,conventional)clinical MRI scanners,which are typically not suited to scan ^(129)Xe nuclei.As a solution to circumvent the translational challenges of hyperpolarized ^(129)Xe,we have recently demonstrated the feasibility of a simple and cheap process for production of proton-hyperpolarized propane gas contrast agent using ultralow-cost disposable production equipment and demonstrated the feasibility of lung ventilation imaging using hyperpolarized propane gas in excised pig lungs.However,previous pilot studies have concluded that the hyperpolarized state of propane gas decays very fast with an exponential decay T1 constant of∼0.8 s at 1 bar(physiologically relevant pressure);moreover,the previously reported production rates were too slow for potential clinical utilization.Here,we investigate the feasibility of high-capacity production of hyperpolarized butane gas via heterogeneous parahydrogen-induced polarization using Rh nanoparticle-based catalyst utilizing butene gas as a precursor for parahydrogen pairwise addition.We demonstrate a remarkable result:the lifetime of the hyperpolarized state can be nearly doubled compared to that of propane(T1 of∼1.6 s and long-lived spin-state TS of∼3.8 s at clinically relevant 1 bar pressure).Moreover,we demonstrate a production speed of up to 0.7 standard liters of hyperpolarized gas per second.These two synergistic developments pave the way to biomedical utilization of proton-hyperpolarized gas media for ventilation imaging.Indeed,here we demonstrate the feasibility of phantom imaging of hyperpolarized butane gas in Tedlar bags and also the feasibility of subsecond 2D ventilation gas imaging in excised rabbit lungs with 1.6×1.6 mm^(2) in-plane resolution using a clinical MRI scanner.The demonstrated results have the potential to revolutionize functional pulmonary imaging with a simple and inexpensive on-demand production of protonhyperpolarized gas contrast media,followed by visualization on virtually any MRI scanner,including emerging bedside low-field MRI scanner technology.展开更多
Objective To investigate the myocardial protective effects of pinacidil induced hyperpolarized arrest and compare with those afforded by conventional depolarized hyperkalemic arrestMethods Eighteen dogs were equal...Objective To investigate the myocardial protective effects of pinacidil induced hyperpolarized arrest and compare with those afforded by conventional depolarized hyperkalemic arrestMethods Eighteen dogs were equally divided into three groups: normothermic hyperpolarized group (Group A), hypothermic hyperpolarized group (Group B), and hyperkalemic group (Group C) Pinacidil (50μmol/L) containing 37℃ St Thomas solution (K+5mmol/L, 10ml/kg), pinacidil (50μmol/L, Sigma, USA) containing 4℃ St Thomas solution (K+ 5mmol/L, 10ml/kg) and 4℃ standard St Thomas solution (K+ 16mmol/L, 10ml/kg) were infused respectively through the aortic root after aorticclamping Heart arrest and its recovery, ultrastructure of the myocardium, the level of serum myocardial enzymes, and lipid peroxide and adenine cleotide of the myocardium were measuredHemodynamics during ischemia and after reperfusion were observedResults The percentages of normal mitochondria and glycogen did not change much during ischemia (except at 60 min) and after reperfusion in B Group, but declined markedly in Group C 30 min and 60 min after ischemia and 20 min after reperfusion (P<0.01) In Group A,they were lower than those of Group B before ischemia, but higher than those of Group C The recoveries of CO, SV, CI, LVSW, RVSW and MAP in Group B were significantly better than those in other two groups 15 min and 30 min after reperfusion (P<0.05and0.01, respectively) However, they were still better in Group A than those in Group C(P<0.05 and 0.01, respectively)The onset of heart arrest was faster in Groups C and B than that in Group A Highly elevated serum myocardial enzymes were observed 60 min after ischemia and 20 min after reperfusion in Group C, while they were only mild in the hyperpolarized groups, especially in Group B, and their recoveries were rapid Adenine nucleotides of the myocardium were better preserved in Group B than in other two groups 30 min, 60 min after ischemia, and 20 min after reperfusion (P<0.05 and 0.01, respectively)They were also much better in Group A than in GroupC(P<0.05and0.01,respectively)Lipid peroxide of the myocardium were significantly lower in Group B than in other groups 20 min after reperfusion (P<0.01),and they were lower in Group A than in Group C(P<0.05) Conclusions Myocardial protection for global ischemia during cardiopulmonary bypass (CPB) could be achieved with hyperpolarized heart arrest induced by pinacidil, an ATP sensitive potassium channel opener,especially in the hypothermic state The protection is weaker in normothermia but is still superior to that with traditional depolarized hyperkalemic arrest展开更多
The relationship among transfer and expression of auxin binding protein gene ( abp ), auxin (NAA) induced plasmalemma hyperpolarity and sensibility to auxin during protoplast culture was studied by measuring transmemb...The relationship among transfer and expression of auxin binding protein gene ( abp ), auxin (NAA) induced plasmalemma hyperpolarity and sensibility to auxin during protoplast culture was studied by measuring transmembrane potential difference (Em) and culturing the protoplasts of sense and antisense abp transgenic tobacco. The concentration of NAA inducing the highest degree of hyperpolarity of sense abp transgenic tobacco protoplasts was lower than the control, and in protoplast culture, their sensibility to auxin increased. The concentration of antisense abp transgenic tobacco protoplasts was higher than the control, and in protoplast culture, their sensibility to auxin decreased. These results demonstrated that ABP synthesized in endoplasmic reticulum needed to transport to cell membrane and functioned there.展开更多
The action potential of pacemaker cells in the sino-atrial node forms the automatic rhythm of the heart. The automatic depolarization in phase 4 is me DaSlS of the automaticity in pacemaker cells. Many currents are in...The action potential of pacemaker cells in the sino-atrial node forms the automatic rhythm of the heart. The automatic depolarization in phase 4 is me DaSlS of the automaticity in pacemaker cells. Many currents are included in phase 4, such as calcium current, TTX-sensitive sodium current, sustained inward current （Isi）, decay of delayed rectifier potassium current, etc. Funny current （If） has long been recognized as important in this phase and is activated at hyperpolarized potentials during cell diastole and in turn activates other currents to form automatic depolarization.展开更多
The action potential （Na<sup>+</sup> spike） of neurons is often followed by a compound after hyperpolarization （AHP） which is mediated by Ca<sup>2+</sup>-dependent K<sup>+</sup>...The action potential （Na<sup>+</sup> spike） of neurons is often followed by a compound after hyperpolarization （AHP） which is mediated by Ca<sup>2+</sup>-dependent K<sup>+</sup> channels. Pyramidal cells in the cerebral cortex are known to have fast, medium and slow AHPs. It is commonly accepted that the fast AHP （fAHP） is mediated by a kind of C- or BK-K<sup>+</sup> channels. The fAHP is characterized by a short duration of about 20 ms, its remarkable voltage dependence and sensitivity to low concentration （【1 mmol/L） of Tetraethylammonium （TEA）.The mAHP results from activation of AHP- or SK-K<sup>+</sup> channels and has a long duration over 200 ms. It is poorly voltage-dependent and blocked by Apamin, but not by TEA.展开更多
Understanding the properties and behavior of water molecules in restricted geometries, such as the nanopores of rocks, is of interest for shale gas exploitation. We present herein ex situ and in situ nuclear magnetic ...Understanding the properties and behavior of water molecules in restricted geometries, such as the nanopores of rocks, is of interest for shale gas exploitation. We present herein ex situ and in situ nuclear magnetic resonance （NMR） studies on the effects of water on the adsorption and diffusion of methane in nanopores. Silica materials with one-dimensional pores of ZSM-22, MCM-41, and SBA-15, with pore sizes ranging from 0.5 to 6 nm, were chosen as models. Hyperpolarized （HP） 129Xe NMR results show that water adsorption does not affect the pore sizes of ZSM-22 and MCM-41 but reduces that of SBA-15. The presence of water suppresses methane adsorption; this suppression effect is stronger in smaller pores. The self-diffusion coefficients of methane within ZSM-22 and MCM-41 are not significantly influenced by the presence of water, as measured by ~H pulsed field gradient （PFG） NMR. However, within SBA-15, which has a pore size of 6 nm, the diffusion coefficient of methane increases as the amount of water adsorption increases, peaks, and then decreases to a constant value with further water adsorption. These experiments reveal the effects of the pore size and the presence of water on methane adsorption and diffusion in constrained spaces, which could have important implications for flow simulations of methane in shales.展开更多
The effects of rises in external K+(Kext) were examined on the hyperpolarization-activated cation current(Ih) in rat dorsal root ganglion neurons using the whole-cell patch clamp technique.The results showed that Kext...The effects of rises in external K+(Kext) were examined on the hyperpolarization-activated cation current(Ih) in rat dorsal root ganglion neurons using the whole-cell patch clamp technique.The results showed that Kext increased Ih in a certain concentration and voltage-dependent manner.At the basal Kext level(4 mmol/L),Ih had a maximal amplitude of 1085 ± 340 pA which was enhanced by ～45% and ～92% at 8 and 16 mmol/L Kext,respectively.The midpoint activation voltage was significantly shifted from -98 mV in the hyperpolarizing direction by 8 and 12 mV at 8 and 16 mmol/L Kext,respectively with alteration of the activation course of Ih.The short time constants of activation became longer with the increasing amplitude of the command potential upon rises in Kext.The long time constants became shorter.The reversal potentials were shifted in the positive direction without significant alterations upon rises in Kext.According to the functional role of Ih,Kext increased Ih,resulting in an enhanced neuronal excitability,which might produce activation potential abnormality and perhaps neuropathic pain involved.展开更多
基金Gants from the National Natural Science Foundation of China(81227902)the Chinese Academy of Sciences(KJCX2-EW-N06-04)
文摘Hyperpolarized^(3)He or^(129)Xe diffusion MRI has been demonstrated as a promising technique for the detection of microanatomical changes in chronic obstructive pulmonary disease(COPD).Compared with ^(3)He,^(129)Xe is more available for the potential clinical applications.However,the measurement of^(129)Xe apparent diffusion coefficient(ADC)possesses more challenges due to the relevant low gyromagnetic ratio and spin polarization.In this present study,a singleb value(b=14 s/cm^(2))diffusion-weighted hyperpolarized^(129)Xe MRI sequence was used to image a balloon phantom,healthy rats,and the COPD rats,respectively.All COPD rats were induced by second-hand smoke and lipopolysaccharide(LPS).The lung^(129)XeADCmaps were obtained on a 7 T MRI scanner.The mean lung parenchymal^(129)XeADCswere 0.04422±0.0029 and 0.04234±0.0023 cm^(2)/s(Δ=0.8/1.2 ms)for the COPD rats,which showed significant increasements in comparison with healthy ones(0.0377±0.0023 and 0.0367±0.0013 cm^(2)/s).Furthermore,the correspondingADChistogram of the COPD rats exhibited a broader distribution as compared with the healthy ones.Our experiments demonstrated that the alveolar airspace enlargement in the COPD rats are able to be quantitatively evaluated by hyperpolarized xenon diffusion-weighted MRI.
基金the National NaturalScience Foundation of China(No: 30570739)
文摘Objective To study the effect of ivabradine on hyperpolarization activated cation current in canine pulmonary vein(PY) sleeve cardiomyocytes with atrial fibrillation.Methods Dissociation of PVs yielded single cardiomyocytes from a Landengorff column without or with pacemaker activity from long-term rapidly atrial pacing (RAP) canines.If current was measured with the whole-cell patch-clamp technique.Results Compared with the control group,the rapidly atrial pacing canine PV cardiomyocytes had spontaneous diastolic depolarization and had larger If densities.Ivabradine (Iva,1 μM),a selective inhibitor of the If current,markedly reduced If currents in the RAP from -2.66±0.4 pA/pF to -1.58±0.1 pA/pF at the test potential of-120 mV (P＜0.01,n=12).Inhibition effect of Iva of If current showed concentration-dependent range from 0.1 to 10.0μM,with IC50 of 2.2 μ M ( 1.8-2.9 μM,95% CL).Furthermore,V1/ of steady-state activated curve was shifted from -84.3±4.9 mV to -106.9±3.4 mV and k value of steady-state activated curve was changed from 12.1+2.6 mV to 9.9±3.4 mV by the application of.1.0 μM Iva ( P＜0.01,n=12).Conclusions Our study revealed that Ivarbadine may significantly decrease If of rapidly atrial pacing pulmonary vein sleeve ceUs with atrial fibdllation.(J Geriatr Cardiol 2008;5:39-42)
基金Supported by the National Natural Science Foundation of China under Grant Nos 81227902 and 81625011the National Key Research and Development Program of China under Grant No 2016YFC1304702the Key Research Program of Frontier Sciences of CAS(QYZDY-SSW-SLH018)
文摘We study the feasibility and safety of human lung hyperpolarized（HP）^（129）Xe magnetic resonance imaging（MRI）.There is no significant change in physiological parameters before and after the examinations of all subjects.Compared with computed tomography, HP^（129）Xe MRI is sensitive to earlier and smaller ventilation defects. The distribution of the HP^（129）Xe MRI signal reflects the pulmonary compliance with the gravity gradient. This is the first application of HP^（129）Xe MRI ventilation imaging in China, and this technology is expected to provide more useful information for clinical practice.
基金the National Natural Science Foundation of China(No.30470559,30330230,30240059)the National Basic Research Development Program(973)of China(No.2007CB512501)Beijing Natural Science Foundation(No.7052039)
文摘Dorsal root ganglion(DRG)neurons have peripheral terminals in skin,muscle,and other peripheral tissues,andcentral
文摘Hyperpolarization-activated cyclic-nucleotide-gated (HCN) channels in the heart modulate cardiac automaticity via the hyperpolarization-activated cation current ( named Ⅰf, Ⅰh, or Ⅰq). Recent studies have unveiled the molecular identity of HCN (HCN1-4) channels. HCN isoforms are unevenly expressed in the heart, even in the sinoatrial node. Features of HCN currents have been characterized in cardiac and other types of cells or in cell lines transfected with the HCN isoforms. The factors modulating Ih and the physiological significance of HCN channels in the heart have been extensively investigated in recent years. The hypothesis for transplanting and/or creating biological pacemakers to replace diseased sinoatrial and/or atrioventricular nodes has been postulated and tested in animal models. Local overexpression of HCN2 channels in the left atrium or in the left conductive bundle branch of the left ventricle via gene delivery induced significant Ⅰh and escape rhythms during vagal stimulation in canines. In addition, implantation of human mesenchymal stem cells with overexpression of HCN2 channels to the canine left ventricular wall was associated with formation of spontaneous escape rhythms of left-sided origin during vagal-stimulation-induced sinus arrest. This preliminary data suggest that the use of HCN channels may hold great promise in,the development of biological pacemakers.
文摘Abstract Hyperpolarization-activated cyclic-nucleotide-gated ( HCN) channels in the heart modulate cardiac automaticity via the hyperpolarization-activated cation current (named If, Ih, or Iq). Recent studies have unveiled the molecular identity of HCN (HCN 1-4) channels. HCN isoforms are unevenly expressed in the heart, even in the sinoatrial node. Features of HCN currents have been characterized in cardiac and other types of cells or in cell lines transfected with the HCN isoforms. The factors modulating Ih and the physiological significance of HCN channels in the heart have been extensively investigated in recent years. The hypothesis for transplanting and/or creating biological pacemakers to replace diseased sinoatrial and/or atrioventricular nodes has been postulated and tested in animal models. Local overexpression of HCN2 channels in the left atrium or in the left conductive bundle branch of the left ventricle via gene delivery induced significant Ih and escape rhythms during vagal stimulation in canines. In addition, implantation of human mesenchymal stem cells with overexpression of HCN2 channels to the canine left ventricular wall was associated with formation of spontaneous escape rhythms of left-sided origin during vagal-stimulation-induced sinus arrest. This preliminary data suggest that the use of HCN channels may hold great promise in the development of biological pacemakers.
基金supported by DOD CDMRP W81XWH-20-10576,W81XWH-20-10578,NSF CHE-1905341 and CHE-1904780,NHLBI R21HL154032 and F32HL160108,R01NS114972,R01NS117146,and R01NS130258.I.V.K.and O.G.S.thank the Russian Science Foundation(Grant#22-43-04426)for financial support.
文摘NMR hyperpolarization dramatically improves the detection sensitivity of magnetic resonance through the increase in nuclear spin polarization.Because of the sensitivity increase by several orders of magnitude,additional applications have been unlocked,including imaging of gases in physiologically relevant conditions.Hyperpolarized ^(129)Xe gas recently received FDA approval as the first inhalable gaseous MRI contrast agent for clinical functional lung imaging of a wide range of pulmonary diseases.However,production and utilization of hyperpolarized ^(129)Xe gas faces a number of translational challenges including the high cost and complexity of contrast agent production and imaging using proton-only(i.e.,conventional)clinical MRI scanners,which are typically not suited to scan ^(129)Xe nuclei.As a solution to circumvent the translational challenges of hyperpolarized ^(129)Xe,we have recently demonstrated the feasibility of a simple and cheap process for production of proton-hyperpolarized propane gas contrast agent using ultralow-cost disposable production equipment and demonstrated the feasibility of lung ventilation imaging using hyperpolarized propane gas in excised pig lungs.However,previous pilot studies have concluded that the hyperpolarized state of propane gas decays very fast with an exponential decay T1 constant of∼0.8 s at 1 bar(physiologically relevant pressure);moreover,the previously reported production rates were too slow for potential clinical utilization.Here,we investigate the feasibility of high-capacity production of hyperpolarized butane gas via heterogeneous parahydrogen-induced polarization using Rh nanoparticle-based catalyst utilizing butene gas as a precursor for parahydrogen pairwise addition.We demonstrate a remarkable result:the lifetime of the hyperpolarized state can be nearly doubled compared to that of propane(T1 of∼1.6 s and long-lived spin-state TS of∼3.8 s at clinically relevant 1 bar pressure).Moreover,we demonstrate a production speed of up to 0.7 standard liters of hyperpolarized gas per second.These two synergistic developments pave the way to biomedical utilization of proton-hyperpolarized gas media for ventilation imaging.Indeed,here we demonstrate the feasibility of phantom imaging of hyperpolarized butane gas in Tedlar bags and also the feasibility of subsecond 2D ventilation gas imaging in excised rabbit lungs with 1.6×1.6 mm^(2) in-plane resolution using a clinical MRI scanner.The demonstrated results have the potential to revolutionize functional pulmonary imaging with a simple and inexpensive on-demand production of protonhyperpolarized gas contrast media,followed by visualization on virtually any MRI scanner,including emerging bedside low-field MRI scanner technology.
基金theNationalNaturalScienceFoundationofChina (No .39760 0 71)
文摘Objective To investigate the myocardial protective effects of pinacidil induced hyperpolarized arrest and compare with those afforded by conventional depolarized hyperkalemic arrestMethods Eighteen dogs were equally divided into three groups: normothermic hyperpolarized group (Group A), hypothermic hyperpolarized group (Group B), and hyperkalemic group (Group C) Pinacidil (50μmol/L) containing 37℃ St Thomas solution (K+5mmol/L, 10ml/kg), pinacidil (50μmol/L, Sigma, USA) containing 4℃ St Thomas solution (K+ 5mmol/L, 10ml/kg) and 4℃ standard St Thomas solution (K+ 16mmol/L, 10ml/kg) were infused respectively through the aortic root after aorticclamping Heart arrest and its recovery, ultrastructure of the myocardium, the level of serum myocardial enzymes, and lipid peroxide and adenine cleotide of the myocardium were measuredHemodynamics during ischemia and after reperfusion were observedResults The percentages of normal mitochondria and glycogen did not change much during ischemia (except at 60 min) and after reperfusion in B Group, but declined markedly in Group C 30 min and 60 min after ischemia and 20 min after reperfusion (P<0.01) In Group A,they were lower than those of Group B before ischemia, but higher than those of Group C The recoveries of CO, SV, CI, LVSW, RVSW and MAP in Group B were significantly better than those in other two groups 15 min and 30 min after reperfusion (P<0.05and0.01, respectively) However, they were still better in Group A than those in Group C(P<0.05 and 0.01, respectively)The onset of heart arrest was faster in Groups C and B than that in Group A Highly elevated serum myocardial enzymes were observed 60 min after ischemia and 20 min after reperfusion in Group C, while they were only mild in the hyperpolarized groups, especially in Group B, and their recoveries were rapid Adenine nucleotides of the myocardium were better preserved in Group B than in other two groups 30 min, 60 min after ischemia, and 20 min after reperfusion (P<0.05 and 0.01, respectively)They were also much better in Group A than in GroupC(P<0.05and0.01,respectively)Lipid peroxide of the myocardium were significantly lower in Group B than in other groups 20 min after reperfusion (P<0.01),and they were lower in Group A than in Group C(P<0.05) Conclusions Myocardial protection for global ischemia during cardiopulmonary bypass (CPB) could be achieved with hyperpolarized heart arrest induced by pinacidil, an ATP sensitive potassium channel opener,especially in the hypothermic state The protection is weaker in normothermia but is still superior to that with traditional depolarized hyperkalemic arrest
文摘The relationship among transfer and expression of auxin binding protein gene ( abp ), auxin (NAA) induced plasmalemma hyperpolarity and sensibility to auxin during protoplast culture was studied by measuring transmembrane potential difference (Em) and culturing the protoplasts of sense and antisense abp transgenic tobacco. The concentration of NAA inducing the highest degree of hyperpolarity of sense abp transgenic tobacco protoplasts was lower than the control, and in protoplast culture, their sensibility to auxin increased. The concentration of antisense abp transgenic tobacco protoplasts was higher than the control, and in protoplast culture, their sensibility to auxin decreased. These results demonstrated that ABP synthesized in endoplasmic reticulum needed to transport to cell membrane and functioned there.
基金This study was supported by the grants from the National"863"Program(No.2001AA2160313)Beijing Important Program Fund of Science and Technology(No.H020220010490)Capital Medical Development Fund of Science and Technology(No.2003-3002)
文摘The action potential of pacemaker cells in the sino-atrial node forms the automatic rhythm of the heart. The automatic depolarization in phase 4 is me DaSlS of the automaticity in pacemaker cells. Many currents are included in phase 4, such as calcium current, TTX-sensitive sodium current, sustained inward current （Isi）, decay of delayed rectifier potassium current, etc. Funny current （If） has long been recognized as important in this phase and is activated at hyperpolarized potentials during cell diastole and in turn activates other currents to form automatic depolarization.
文摘The action potential （Na<sup>+</sup> spike） of neurons is often followed by a compound after hyperpolarization （AHP） which is mediated by Ca<sup>2+</sup>-dependent K<sup>+</sup> channels. Pyramidal cells in the cerebral cortex are known to have fast, medium and slow AHPs. It is commonly accepted that the fast AHP （fAHP） is mediated by a kind of C- or BK-K<sup>+</sup> channels. The fAHP is characterized by a short duration of about 20 ms, its remarkable voltage dependence and sensitivity to low concentration （【1 mmol/L） of Tetraethylammonium （TEA）.The mAHP results from activation of AHP- or SK-K<sup>+</sup> channels and has a long duration over 200 ms. It is poorly voltage-dependent and blocked by Apamin, but not by TEA.
文摘Understanding the properties and behavior of water molecules in restricted geometries, such as the nanopores of rocks, is of interest for shale gas exploitation. We present herein ex situ and in situ nuclear magnetic resonance （NMR） studies on the effects of water on the adsorption and diffusion of methane in nanopores. Silica materials with one-dimensional pores of ZSM-22, MCM-41, and SBA-15, with pore sizes ranging from 0.5 to 6 nm, were chosen as models. Hyperpolarized （HP） 129Xe NMR results show that water adsorption does not affect the pore sizes of ZSM-22 and MCM-41 but reduces that of SBA-15. The presence of water suppresses methane adsorption; this suppression effect is stronger in smaller pores. The self-diffusion coefficients of methane within ZSM-22 and MCM-41 are not significantly influenced by the presence of water, as measured by ~H pulsed field gradient （PFG） NMR. However, within SBA-15, which has a pore size of 6 nm, the diffusion coefficient of methane increases as the amount of water adsorption increases, peaks, and then decreases to a constant value with further water adsorption. These experiments reveal the effects of the pore size and the presence of water on methane adsorption and diffusion in constrained spaces, which could have important implications for flow simulations of methane in shales.
基金Supported by the University of Science and Technology Foundation of Shanxi Province (Grant No. 200713010)
文摘The effects of rises in external K+(Kext) were examined on the hyperpolarization-activated cation current(Ih) in rat dorsal root ganglion neurons using the whole-cell patch clamp technique.The results showed that Kext increased Ih in a certain concentration and voltage-dependent manner.At the basal Kext level(4 mmol/L),Ih had a maximal amplitude of 1085 ± 340 pA which was enhanced by ～45% and ～92% at 8 and 16 mmol/L Kext,respectively.The midpoint activation voltage was significantly shifted from -98 mV in the hyperpolarizing direction by 8 and 12 mV at 8 and 16 mmol/L Kext,respectively with alteration of the activation course of Ih.The short time constants of activation became longer with the increasing amplitude of the command potential upon rises in Kext.The long time constants became shorter.The reversal potentials were shifted in the positive direction without significant alterations upon rises in Kext.According to the functional role of Ih,Kext increased Ih,resulting in an enhanced neuronal excitability,which might produce activation potential abnormality and perhaps neuropathic pain involved.
