核磁共振成像及其发展

核磁共振（nuclear magnetic resonance，简称NMR）是1946年由美国F.Bloch和E.Purcell发现并应用的，为此他们获得1952年诺贝尔奖金，1972年美国Damadian指出NMR用于医学诊断的可能性。1973年美国P.Lauferber发表了核磁共振成像原理的论文，引起了广泛的兴趣和重视。随着扫描成像技术（CT）的发展日致成熟，近几年来核磁共振成像技术获得迅速发展并开始临床应用。目前世界上有200多台成像装置，各国公司正在相竞研制生产，其发展前景是令人瞩目的。     

葡萄球菌蛋白A胶体金分子三维构象的原子力显微镜分析

目的　确定葡萄球菌蛋白A胶体金分子特征性构象。　方法　应用原子力显微镜扫描生理状态下分布在云母表面的葡萄球菌蛋白A胶体金分子 ,并进行理论计算。　结果　葡萄球菌蛋白A胶体金分子为 5 7.0 0nm× 33.0 0nm× 2 1.6 1nm椭圆球形“左轮手枪状”复合物。　结论　原子力显微镜可以在生理状态下直观测定生物大分子纳米尺度结构。葡萄球菌蛋白A胶体金分子的特征性结构可以作为神经细胞膜表面N -甲基 -D -天冬氨酸受体 (NMDAR)原子力显微镜观测的原位标记物。     

测定有机磷化合物结构的核磁共振新方法

报道二种用于测定有机磷化合物结构的核磁共振新方法,~(13)CSLDEPT和~(31)PSLPT。它们以选择性质子软脉冲的远程磁极化转移为基础,所提供的~1H—~(13)C和~1H—~(31)P的相关信号可以直接用于识别核磁共振谱峰、连接结构单元,确定分子结构。与二维异核远程核磁共振方法相比,这二种方法都具有灵敏度高、数字分辨率好和使用方便等特点。     

鼻咽癌放射性脊髓病及核磁共振成像诊断的优越性

我院自１９８８年１月至１９９４年１２月收治首程放疗鼻咽癌９３８例，随诊中６例发生放射性脊髓病，均经核磁共振成像（ＭＲＩ）检查诊断。本文根据临床资料，分析其发病规律及ＭＲＩ诊断的优越性。１材料和方法该６例病人均经病理诊断为鼻咽癌，放疗采用加速器８ＭＶＸ...     

急性运动及恢复期大鼠RBCM蛋白构象改变的ESR研究

利用电子自旋共振（ＥＳＲ）技术，以大鼠递增负荷力竭性运动为模型，测定急性运动中及不同时程恢复期红细胞膜（ＲＢＣＭ）蛋白构象的改变。结果表明：ＲＢＣＭ蛋白构象在运动中（３级负荷未）即出现明显改变（ｐ＜０．００１），认为主要由机械因素引起；至运动后即刻达最显著变化，考虑脂质过氧化作用不足及膜蛋白的生物物理特性可能对蛋白构象继续改变起作用；运动后４ｈ膜蛋白运动减慢，与即刻比ｐ＜０．０５，可能与膜蛋白构象恢复或／和脂质过氧化引起的蛋白分子交联有关；直至运动后２４ｈ仍未恢复至正常水平。     

颅脑伤后持续性植物状态100例脑组织的核磁共振变化

目的：为了明确创伤性持续性植物状态（PVS）脑损伤的部位、性质和脑组织结构的变化特征。方法：采用MRI对创伤性PVS患者100例进行病灶的定位、定性断定，且进行统计。结果：100例PVS患者中，发现病灶1154处（出血性462处，非出血性692处），每例5－19处，平均约12处病灶。弥漫性脑白质轴索损伤和胼胝体损伤94例，脑干背侧损伤87例，基底节和丘脑损伤分别为52例和32例，大脑皮层伤50例（以额、颞叶居多），海马旁伤47例。结论：创伤性PVS主要是由于弥漫性轴索损伤。统计结果表明，临床与MRI密切结合对确诊脑外伤后PVS有重要意义。     

生物样品中微量氟乙酸钠和氟乙酰胺的核磁共振测定技术…

氟乙酸和氟乙酰胺是国家禁用的剧毒灭鼠剂，但一些地方仍在非法使用，给人民生命财产造成秀大危害。本研究报道一种氟乙酸钠和氟乙酰胺的核磁共振测定技术，其灵敏度比国内外同类方法高４倍以上，能够准确鉴定生物样品中微量含氟灭鼠剂。用该技术首次查明了１９９５年广东省高要市大型中毒事件的原因，在中毒病人的抢救与治疗，公安系统侦破此案过程中起到了关键作用。     

13C NMR investigation of synovial fluids

¹³C NMR spectra of synovial fluids from 20 patients suffering from rheumatic diseases have been recorded. Structural changes in hyaluronic acid, the main carrier of the viscoelastic properties of synovial fluid, could be observed in the NMR spectra of the native biological fluid. By comparing these spectra with those of purified hyaluronic acid, a rough estimation of the degree of depolymerization of synovial hyaluronlic acid was possible. The patients with rheumatoid arthritis appeared to have a lower degree of polymerization compared to patients with osteoarthrosis. Thus, ¹³C NMR spectroscopy prolvides useful information about biophysical properties of sartorial fluid.     

31P NMR investigation of energy metabolism in perifused MMQ cells

The MMQ cell line is a unique prolactin-secreting rat pituitary cell line. MMQ cells entrapped in agarose gel threads are metabolically active, as determined by the uptake and phosphorylation of creatine and the maintenance of high energy phosphates for over 15 h. Forskolin activates the catalytic subunit of adenylyl cyclase and, in MMQ cells, elevates the level of cAMP and stimulates prolactin secretion. ³¹P NMR spectroscopy was used to investigate the energy metabolism of the MMQ cells during stimulation by forskolin. The ability to measure small changes in the energy status of these cells was enhanced by increasing the PCr levels in the cells. Administration of forskolin to the perifused MMQ cells resulted in acute, reversible, and dose-dependent changes in the ³¹P NMR spectra of the cells within 12 to 24 min of the beginning of forskolin exposure. Several lines of evidence indicate that the changes observed in the MMQ cells are the composite result of the interaction of forskolin with adenylyl cyclase and the plasma membrane glucose transporter. Also, preincubation of the MMQ cells with the dopamine agonist, bromocriptine, attenuates the forskolin-stimulated decrease in the PCr resonance by approximately 50%. This attenuation indicates that the forskolin-stimulated changes in energy metabolism are probably related to the prolactin secretion process.     

Multinuclear NMR investigation of probe construction materials at 9.4T.

This work investigates probe construction materials for their signal contribution to ultrashort echo time spectroscopy and imaging. (1)H, (13)C, and (31)P spectra were obtained at a field strength of 9.4 T for 16 materials considered for use in probe and holder design and construction. Four of the materials were found to be suited for the construction of NMR probes, housing of RF coils, and holders for in vivo experiments.     

NMR imaging of the brain

Summary The basic features of an NMR imaging system are outlined and three pulse sequences which produce images with varying dependence on proton density T₁ and T₂ are described. The first of these sequences, Repeated Free Induction Decay produces images which demonstrate changes in proton density as well as flow effects. The second sequence, Inversion-recovery, produces images which are dependent on T₁ and show a high level of grey, white matter contrast giving considerable anatomical detail. In addition pathological processes such as infarction, haemorrhage, demyelination and malignancy produce changes in T₁ enabling lesions to be localised. The third sequence, Spin-echo, produces images which are dependent on T₂. These show very little grey, white matter contrast but demonstrate acute and space occupying lesions as well as cerebral oedema. The high level of grey, white matter contrast, lack of bone artefact, variety of sequences, capacity for multiplanar imaging, sensitivity to pathological change and lack of known hazard make NMR an important addition to existing techniques of neurological diagnosis.     

High-resolution (1)H NMR and magic angle spinning NMR spectroscopic investigation of the biochemical effects of 2-bromoethanamine in intact renal and hepatic tissue.

The metabolic consequences of xenobiotic-induced toxicity were investigated using high-resolution magic angle spinning (MAS) NMR spectroscopy of intact tissue. Renal papillary necrosis (RPN) was induced in Sprague-Dawley rats (n = 12) via a single i.p. dose of 250 mg/kg 2-bromoethanamine (BEA) hydrobromide. At 2, 4, 6, and 24 h after treatment with BEA, three animals were killed and tissue samples were obtained from liver, renal cortex, and renal medulla. Tissue samples were also removed at 2 and 24 h from matched controls (n = 6). (1)H MAS NMR spectroscopic techniques were used to analyze samples of intact tissue ( approximately 10 mg). Decreased levels of nonperturbing renal osmolytes (glycerophosphocholine, betaine, and myo-inositol) were observed in the renal papilla of BEA-treated animals at 6 and 24 h postdose (p.d.), concomitant with a relative increase in the tissue concentration of creatine. Increased levels of glutaric acid were found in all tissues studied in BEA-treated animals at 4 and 6 h p.d., indicating the inhibition of mitochondrial fatty acyl CoA dehydrogenases and mitochondrial dysfunction. Increased levels of trimethylamine-N-oxide occurred in the renal cortex at 6 h p.d. Changes in the metabolite profile of liver included an increase in the relative concentrations of triglycerides, lysine, and leucine. The novel application of (1)H MAS NMR to the biochemical analysis of intact tissues following a toxic insult highlights the potential of this technique as a toxicological probe in providing a direct link between urinary biomarkers of toxicity and histopathological evaluation of toxicological lesions.     

NMR anatomy of the brain using inversion-recovery sequences

Summary The use of NMR inversion-recovery (IR) sequences to demonstrate brain anatomy is illustrated. The high level of grey-white matter contrast is of value in localising anatomical structures and demonstrating myelination during childhood. While the resemblance of IR scans to gross anatomical sections in different planes is close, it is limited by the spatial resolution of the NMR scanner, artefacts and partial volume effects.     

Cerebral NMR: diagnostic evaluation of brain tumors by partial saturation technique with resistive NMR

Summary One hundred and forty patients with cerebral neoplasms were examined in a 0.12-Tesla prototype resistive NMR proton imaging device by partial saturation technique. NMR was superior to CT in tumor and edema localization and equal to CT in tumor and edema detection. NMR, however, was not able to clearly separate tumor from edema, a separation that contrast enhanced CT achieved.