Langendorff灌流心脏的31P NMR谱测定

测定了Langendorff灌流大鼠和兔心脏的³¹P NMR谱.观测到PCr、ATP、SP、P_i以及PME和GPC等含磷代谢物的共振峰,各谱峰之间实现了很好的分辨.在3~5min的累加时间内测得的图谱具有较好的S/N,可用于以上含磷代谢物的定量测定,以高能含磷化合物ATP和PCr相对峰强度以及冠脉流量的变化对灌流大鼠心脏代谢的稳定性进行了考察,结果表明,在本实验条件下大鼠心脏的能量储存至少可稳定2h,用所建方法以3min的时间间隔对同一大鼠心脏缺血21min及再灌注12min过程中心脏的³¹P NMR谱进行了连续跟踪测定,并初步观测了缺血及再灌注过程中心肌细胞内ATP、PCr与P_i之间的消长关系.     

离体心脏的31P NMR谱

³¹P NMR谱自70年代后期开始被用于离体心脏中含磷化合物代谢的动态研究.^3lP NMR谱不仅可以鉴定心肌组织中浓度较高的含磷化合物,即ATP、磷酸肌酸和无机磷酸盐,而且可提供有关这些化合物化学环境(包括pH和Mg²⁺)和细胞内分布的信息.利用这一非损伤性的定量分析方法,可连续观测心肌的代谢并可同时测定离体心脏的机械功能.利用饱和转移技术还能对完整心脏中肌酸激酶和腺苷酸激酶反应的速率加一测定.本文综述介绍了近年来进行离体灌流心脏^3lP NMR谱测定的实验方法以及这一技术所提供的各种信息.     

急性低氧大鼠脑31P核磁共振波谱研究

³¹P磁共振波谱是目前唯一可以用作在体无损伤的检测细胞水平能量代谢变化的非侵入性技术,可测得脑内多种能量代谢产物.目的：急性低氧大鼠脑组织的³¹P MRS检测.方法：(1)20只成年SD大鼠分为4组：低氧0min(对照),5min,10min,15min后,迅速液氮冷冻;(2)将脑组织研碎后,加入高氯酸(PCA),冷冻干燥;(3)将提取物用0.5mL D\-2O溶解后进行MRS检测.结果：(1)急性低氧早期即引起³¹P MRS中PCr和ATP峰降低,ADP和Pi峰增高,PCr/Pi和ATP/Pi降低,而ADP/ATP增高.可交换磷池(EPP)中PCr的正常值为42.4%,低氧5min后降到28.9%, ATP从33.8%降到19.2%,Pi从17.7%升到42.0%.(2)急性低氧时³¹P MRS中脑内磷酯分解代谢产物GPC、GPE含量增加,说明低氧早期脑内即有膜磷酯的分解增加.结论：³¹P磁共振波谱可用于脑低氧性疾病的诊断,我们波谱中最敏感的指标是PCr/Pi和ATP/Pi,尤其早期降低更为显著.     

紫杉醇治疗小鼠S180肉瘤的体内31P MRS研究

为了研究紫杉醇治疗小鼠S180肉瘤的³¹P MRS参数的变化及这些参数的变化是否早于常规观察的瘤体积的变化.方法:利用表面线圈³¹P NMR方法,研究小鼠皮下接种的S180肉瘤.结果:用药48h后给药组的PCr/Pi、β-NTP/Pi、PME/β-NTP比值与对照组有显著性差别(P<0.05),而肿瘤体积在给药组和对照组之间无显著性差别,³¹P MRS参数的变化早于瘤体积变化.结论:小鼠S180肉瘤³¹P MRS不仅可以给出定量的结果,而且可以较早地显示出治疗的效果.     

大鼠急性缺血心肌31P磁共振波谱的基础研究

利用³¹P磁共振波谱（MRS）检测了急性缺血心肌组织提取物中高能磷酸化合物的变化. 方法：成年SD大鼠在心肌梗塞后0、5、 20、45 min后进行取材,梗塞区、边缘区及正常区的心肌组织经高氯酸萃取后进行高分辨MRS检测. 结果：梗塞区,缺血5 min PCr/Pi比值下降到对照组的12 ％;20 min ATP/Pi 比值下降至0.05,Pi/EPP比值上升至0.8;45 min 梗塞区PDE/ATP上升至1.93,与45 min心肌的不可逆损伤超微结构相吻合. 边缘区各代谢产物出现改变的程度要小于梗塞区,大于正常区. 正常区也有能量代谢的改变. 结论：心肌组织的³¹P MRS能够反映心肌缺血后心肌不同部位的动态能量代谢改变. PDE/ATP是判断心肌不可拟性损伤的可靠指标.     

小鼠大脑急性缺血过程中31P NMR研究

利用³¹P NMR研究了小鼠大脑在急性缺血状态下能量代谢的特点,结扎带迷走神经的颈总动脉后,PCr/Pi、β-ATP/Pi比值迅速下降,且PCr/Pi下降速度较快,同时脑细胞内酸中毒加重.缺血5min后恢复供血,可部分地逆转缺血造成的损伤.     

人淋巴瘤白血病细胞系Molt-4的31P核磁共振研究

用³¹P核磁共振(NMR)观察了人淋巴瘤白血病细胞系Molt-4的³¹P谱.NMR测试温度为37℃、20℃和4℃时,随着测试时间增长,细胞³¹P谱中ATP峰降低,无机磷峰升高,细胞³¹P谱的变化随测试温度降低依次减缓.实验温度为4℃,从收集细胞至开始NMR累加在30min内,NMR累加在60min内,获得活细胞的稳定的³¹P谱.根据细胞内无机磷的化学位移数值,对细胞内pH值进行了测定.     

活体动物代谢过程的31P NMR研究——方法与初步结果

利用表面线圈探头测得了小鼠大脑,大腿肌肉和肝脏的体内³¹P NMR谱图。观察到PCr,ATP,PME,PDE,P_i等化合物的共振峰,并确定了各谱峰的化学位移。由大脑的P_i化学位移计算得到其细胞内pH值为7.15.用差谱方法解决了因定位不准而造成的肝脏谱图不纯。观察了小鼠大脑在缺氧状态下的代谢变化过程。当O₂浓度降至2%时,PCr开始下降,降到1%时,P_i明显升高。从空气变化到1%的O₂含量,致使小鼠死亡,小鼠大脑的pH值从7.16降到6.46。     

鼠S180肉瘤的体内31P MRS研究

利用表面线圈³¹P NMR研究了小鼠S180肉瘤生长过程中能量代谢和磷脂类变化的特点.结果发现:随着肿瘤体积的增大,(1)Pi和PME升高;(2)PCr降低,在肿瘤体积较大时常检测不到;(3)β-NTP(通常用来表示ATP的量)变化较小;(4)PDE波动性较大;(5)PCr/Pi和β-NTP/Pi比值均下降,且PCr/Pi比β-NTP/Pi下降得快;(6)PME/β-NTP比值升高;(7)肿瘤pH下降,且与PCr/Pi、β-NTP/Pi或(PCr+β-NTP)/Pi比值有相关性.讨论了与这些参数变化相关联的生物学意义.     

活体肝胵Fasciola hepatica及其高氯酸萃取物的31P及13C NMR研究

本工作报道了用³¹P NMR谱定量分析活体肝胵Fasiciola hepatica中含磷化合物的实验方法及一些初步结果,测定了活体肝胵体内含磷化合物的弛豫时间T₁,观察了无灌注循环系统时肝胵体内pH值变化。利用高氯酸萃取物测得的³¹P NMR谱,定出了各谱峰的归属,观察了用含糖及缺糖培养液培养的肝胵糖类养料的代谢变化,并利用¹³C NMR谱肯定了肝胵体内主要含磷化合物之一的α-甘油磷酰胆碱³¹P NMR谱峰的归属。     

In vivo 31P MRS of human brain at high/ultrahigh fields: a quantitative comparison of NMR detection sensitivity and spectral resolution between 4 T and 7 T

The primary goal of this study was to establish a rigorous approach for determining and comparing the NMR detection sensitivity of in vivo ³¹P MRS at different field strengths (B₀). This was done by calculating the signal-to-noise ratio (SNR) achieved within a unit sampling time at a given field strength. In vivo ³¹P spectra of human occipital lobe were acquired at 4 and 7 T under similar experimental conditions. They were used to measure the improvement of the human brain ³¹P MRS when the field strength increases from 4 to 7 T. The relaxation times and line widths of the phosphocreatine (PCr) resonance peak and the RF coil quality factors (Q) were also measured at these two field strengths. Their relative contributions to SNR at a given field strength were analyzed and discussed. The results show that in vivo ³¹P sensitivity was significantly improved at 7 T as compared with 4 T. Moreover, the line-width of the PCr resonance peak showed less than a linear increase with increased B₀, which leads to a significant improvement in ³¹P spectral resolution. These findings indicate the advantage of high-field strength to improve in vivo ³¹P MRS quality in both sensitivity and spectral resolution. This advantage should improve the reliability and applicability of in vivo ³¹P MRS in studying high-energy phosphate metabolism, phospholipid metabolism and cerebral biogenetics in the human at both normal and diseased states noninvasively. Finally, the approach used in this study for calculating in vivo ³¹P MRS sensitivity provides a general tool in estimating the relative NMR detection sensitivity for any nuclear spin at a given field strength.     

Spin-lattice relaxation times and nuclear overhauser enhancement effect for P metabolites in model solutions at two frequencies: Implications for in vivo spectroscopy

The relaxation time T₁ values and nuclear Overhauser enhancement factor for ³¹P signal were determined in model solutions of metabolites ATP, PCr and Pi, and AMP at two frequencies and in H₂O and ²H₂O solutions. The data were analyzed to resolve the contribution of different relaxation mechanisms. A knowledge of NOE is important in the light of recent applications of double resonance methods to enhance the sensitivity of in vivo ³¹P spectroscopy. The results show that chemical shift anisotropy is the dominant mechanism for ³¹P in ATP at the high field, whereas the dipolar interaction mechanism is the main feature for the ³¹P relaxation of PCr and Pi. The dipolar mechanism responsible for NOE originates from interactions of solvent water with ³¹P moiety. Implications for in vivo spectroscopy are indicated.     

反应物NO的振动激发对反应C(3P)+NO(X2Π)→CO(X1Σ+)+N(2D)立体动力学性质的影响

采用准经典轨线方法研究碰撞能为0.23 eV时,反应物分子NO在不同初始振动态（v=0~3）下发生在两个电子态（²A″和²A'）势能面上反应C（³P）+NO（X²Π）→CO（X¹Σ⁺）+N（²D）的立体动力学性质。计算反应产物的转动角动量矢量分布（P（θ_r）和P（φ_r））以及微分散射截面（P₀₀（ω_t）,P₂₀（ω_t））。结果表明：反应物的振动激发对发生在²A'势能面上的反应立体动力学性质影响显著,而对发生在²A″势能面上的反应立体动力学性质影响较小,这可能与两个势能面的构型有关。在两个电子态势能面上发生的反应均受内平面反应机理支配。     

Metabolite mapping of human filarial parasite, Brugia malayi with nuclear magnetic resonance

Metabolite mapping of human filarial parasite, Brugia malayi was carried out in vitro as well as in situ in host Mastomys coucha by ³¹P nuclear magnetic resonance (NMR) spectroscopy. Detection of parasites by visualizing contrast spots due to pathologic changes was observed by ¹H magnetic resonance imaging (MRI). Major metabolites of adult B. malayi observed by ³¹P-NMR spectroscopy were of sugar phosphates (SP), phosphomonoesters (PME), glycerophosphoryl-ethanolamine (GPE), -choline (GPC), phosphoenolpyruvate (PEP), inorganic phosphate (Pi), nucleoside diphosphosugar and nucleotides-mono, -di and -tri phosphates. PEP and GPC were present in high concentration; PEP being the major energy reservoir and GPC the major phospholipid in this species of filaria. The ³¹P NMR spectra of testis of mastomys, showed seven major peaks of SP, PME, phosphocreatine (PCr), phosphodiesters (PDE), Pi, and nucleotides di- and tri-phosphates. The ³¹P-NMR spectra of testis of B. malayi infected animal also consisted of seven major peaks with significant decrease in the SP and PME peak showing changes in the carbohydrate and lipid metabolism of filaria infected testis. Thus, in vivo ³¹P MRS provided a non-invasive assessment of tissue bioenergetics and phospholipid metabolism.     

NMR-spectroscopic study of Pb in pure and barium diluted lead phosphate

³¹P and ²⁰⁷Pb MAS and static ²⁰⁷Pb NMR spectra of Pb₃(PO₄)₂ and (Pb_1−xBa_x)₃(PO₄)₂ (x=0.08, 0.12) are analysed. The resonances stemming from different cation sites are correlated with the corresponding local symmetry and their oxygen neighbours. The coordination sphere of Pb(1) consists of 12 oxygen atoms and shows characteristics of a near-axial arrangement with a comparatively low anisotropy. The tenfold coordinated Pb(2) atoms are located in a more anisotropically-coordinated site. In Pb-diluted lead phosphate crystals the Pb(2) positions appear to be preferentially substituted by barium. There are indications that the cation distributions in the diluted samples are inhomogeneous. Furthermore, ³¹P MAS NMR experiments indicate a single phosphorus position.     

1D and 2D solid state NMR investigations of the framework structure of As-synthesized AlPO4-14

The framework structure of As-synthesized A1PO₄-14 has been investigated with a combination of different one-dimensional ²⁷Al and ³¹P solid state NMR techniques and ²⁷Al/³¹P double resonance methods. The results are found to be fully consistent with the assumed structural model. ²⁷Al MAS and DOR experiments at three different magnetic field strengths together with simulations show the presence of two tetrahedral sites, one pentacoordinated and one octahedral aluminum site. The ²⁷Al quadrupolar coupling constants and the ³¹P isotropic chemical shifts of the tetrahedral sites correlate well with tetrahedral shear-strain parameters and mean P-O-A1 bond angles, respectively. These correlations allow one to assign all of the NMR resonances to specific T-sites in the proposed framework structure. The assignments are then further confirmed by the application of three different two-dimensional heteronuclear correlation methods (i.e., ²⁷Al → ³¹P TEDOR, CP, and INEPT) which reveal the connectivities between AlO_x and PO₄ polyhedra. The two-dimensional INEPT experiment is applied here for the first time in the solid state.