基于支持向量机的~(31)P磁共振波谱肝细胞癌诊断

支持向量机是在统计学习理论基础上发展起来的一种新的机器学习方法,在模式识别领域有着广泛的应用。利用基于支持向量机模型的31P磁共振波谱数据对肝脏进行分类,区别肝细胞癌,肝硬化和正常的肝组织。通过对基于多项式核函数和径向基核函数的支持向量机分类器进行比较,并且得到三种肝脏分类的识别率。实验表明基于31P磁共振波谱数据的支持向量机分类模型能够对活体肝脏进行诊断性的预测。     

31p磁共振波谱物质检测准确性的验证研究

目的:评价1.5T磁场下31PMRS磷化合物检测的准确性.方法:以卵磷脂为参照标准品,对照研究对同一位正常志愿者骨骼肌肉磷谱代谢特征,对其股骨下端先后行两次相同参数、相同条件状态下的31P波谱检测,第二次检测时在感共趣区内体外加入卵磷脂标准品,对比两次检测的结果变化.结果:对同一位正常志愿者先后两次进行渡谱检测,加入卵磷脂后各代谢物波谱变化为β-ATP:-24.46,α-ATP:+82.61,γ-ATP:-32.89,PCr:+64.32,Pi.+110.5,PDE:+462.57,PME:+15.71.加入卵磷脂后,PDE峰改变最明显.结论:1.5T磁场下31P MRS能准确检测体内化合物的存在及其定量分析,研究结果可信.     

肝脏肿瘤的31P 磁共振波谱研究进展

磁共振渡谱（MRS）在基础医学和临床医学中起着越来越重要的作用,是目前对人体唯一无创的研究活体组织器官代谢、生化变化及化合物定量分析的方法,能显示肿瘤和正常组织之间的不同代谢。能在分子水平上反映病理情况。磷是能量代谢的重要要素,肝脏中许多化合物都含有31P,本文就31P磁共振渡谱在肝癌的研究及,临床应用方面的近况进行综述。     

^H磁共振波谱在脑胶质瘤的应用进展

磁共振波谱（magnetic resonance spectroscopy,MRS）技术的出现使活体检测组织的代谢和生化信息成为可能,随着其技术的不断成熟,其在临床的应用范围日益扩大。脑胶质瘤具有与正常脑组织不同的代谢特征,借助MRS技术一方面可以反映其代谢特征,另外可将其与正常脑组织区分,因此MRS技术特别是^1H-MRS在脑胶质瘤的诊断、鉴别诊断、分级及预后评估中应用日益广泛。本文就相关进展进行综述。     

基于遗传算法特征选择的HBV再激活分类预测模型

探讨原发性肝癌患者精确放疗后乙型肝炎病毒(hepatitis b virus,HBV)再激活的危险特征和分类预测模型。提出基于遗传算法的特征选择方法,从原发性肝癌数据的初始特征集中选择HBV再激活的最优特征子集。建立贝叶斯和支持向量机的HBV再激活分类预测模型,并预测最优特征子集和初始特征集的分类性能。实验结果表明,基于遗传算法的特征选择提高了HBV再激活分类性能,最优特征子集的分类性能明显优于初始特征子集的分类性能。影响HBV再激活的最优特征子集包括:HBV DNA水平,肿瘤分期TNM,Child-Pugh,外放边界和全肝最大剂量。贝叶斯的分类准确性最高可达82.89%,支持向量机的分类准确性最高可达83.34%。     

用~（31）P磁共振谱对艾氏腹水癌和肉瘤S－180细胞代谢的研究

艾氏腹水癌细胞和肉瘤Ｓ－１８０细胞是抗肿瘤药物筛选常用细胞株．实验采用取自小鼠腹腔的第７～８天的艾氏腹水癌和Ｓ－１８０细胞,用３１Ｐ磁共振谱测得了细胞内小分子含磷代谢成分;计算了细胞内ｐＨ值;还用３１Ｐ谱探讨了作用机制不同的三种抗代谢物：碘乙酸、２,４－二硝基苯酚及棉酚对艾氏腹水癌细胞代谢的影响     

增强P18~(INK4C)表达对胃腺癌细胞侵袭的影响(英文)

在应用基因芯片技术筛选胃腺癌转移相关基因的过程中 ,发现CDK抑制因子P18INK4C在人类胃腺癌转移细胞株RF 4 8中的表达较其原发灶细胞株RF 1明显下调 .这提示P18INK4C表达差异与胃腺癌细胞的侵袭转移可能有一定程度的相关性 .通过构建P18INK4C 表达质粒并将其转染入RF 4 8增强P18INK4C的表达 ,研究其对胃腺癌原发灶细胞体外运动、侵袭转移能力以及生长特性的影响 ,进一步明确P18INK4C与人类胃腺癌侵袭转移之间的关系 .结果发现 ,增强P18INK4C表达可以使胃腺癌原发灶细胞的体外侵袭能力明显下降 ,而对RF 4 8的细胞周期和生长增殖能并力未产生影响 .上述结果提示 ,P18INK4C参与人类胃腺癌转移过程 ,在此过程中其主要的作用可能并不是调节细胞周期 ,而是与胃腺癌原发灶细胞侵袭转移能力的调节密切相关 .     

两个特用稻的营养供应水平与~(32)P、~(14)C分布和谷产量的关系

香稻(竹香粘)的分蘖数多,其分蘖期根系吸收~(32)P和~(32)P分布到分蘖,以高、中肥和高N,高K肥处理的为高;~(14)C-葡萄糖同化物分布在分蘖比黑米稻(黑优粘)和常规稻“双桂36”的高,但灌浆期和黄熟期~(14)C分布在稻穗较少.低肥处理的稻谷产量较高.而在高、中肥条件下结实率降低,实粒数减少,成穗率稍低,谷产量也比“黑优粘”和“双桂36”低. “黑优粘”在高肥、高N条件下的分蘖多,成穗率高、结实粒数也较多,稻谷产量比“竹香粘”高,在高、中肥、高 N高 P条件下,~(32)P分布于分蘖多,分蘖的~(14)C分布则以高 N,高 K肥条件下的多;开花和灌浆用稻穗的~(14)C分布皆以高 K肥水平的为高。“黑优粘”是耐肥和需钾肥品种,高肥、高K可提高其稻谷产量,但仍比“双桂36”低.     

基于模拟退火算法的高分辨率蛋白质质谱数据特征选择

蛋白质质谱技术是蛋白质组学的重要研究工具,它被出色地应用于癌症早期诊断等领域,但是蛋白质质谱数据带来的维灾难问题使得降维成为质谱分析的必需的步骤。本文首先将美国国家癌症研究所提供的高分辨率SELDI—TOF卵巢质谱数据进行预处理;然后将质谱数据的特征选择问题转化成基于模拟退火算法的组合优化模型,用基于线性判别式分析的分类错误率和样本后验概率构造待优化目标函数,用基于均匀分布和控制参数的方法构造新解产生器,在退火过程中添加记忆功能;然后用10-fold交叉验证法选择训练和测试样本,用线性判别式分析分类器评价降维后的质谱数据。实验证明,用模拟退火算法选择6个以上特征时,能够将高分辨率SELDI—TOF卵巢质谱数据全部正确分类,说明模拟退火算法可以很好地应用于蛋白质质谱数据的特征选择。     

~(32)P研究马铃薯(合作-88)和黄豆对磷素营养的吸收及分布规律

应用3 2 　P研究“合作 88”马铃薯对磷素营养的吸收和分布规律 ,结果显示 :马铃薯对磷素营养的吸收率随植株的生长而增加。吸收率与栽培生长时间呈显著正相关。磷素主要分布为茎 >根 >叶。随生育期茎中含量相对增加 ,而叶中含量相对减少 ,根的不变。黄豆对磷素的吸收在 6d水培时间内随时间的延长而增加 ,过后则衰退。     

神经网络提高肝细胞癌磁共振波谱诊断正确率

通过评价31磷磁共振波谱(31Phosphorus Magnetic Resonance Spectroscopy,31P-MRS)来辨别三种诊断类型:肝细胞癌,正常肝和肝硬化。运用反向传输神经网络(BP)和径向基函数神经网络(RBF)分析31P-MRS数据,分别建立神经网络模型,进行肝细胞癌的诊断分类以期提高识别率。实验结果证明,应用神经网络模型后,31P-MR波谱对活体肝细胞癌的诊断正确率从89.47%提高到97.3%,且BP更优于RBF。     

Phosphorus magnetic resonance spectroscopy: its utility in examining the membrane hypothesis of schizophrenia

A novel approach to understanding the pathophysiology of schizophrenia has been the investigation of membrane composition and functional perturbations, referred to as the "Membrane Hypothesis of Schizophrenia." The evidence in support of this hypothesis has been accumulating in findings in patients with schizophrenia of reductions in phospholipids and essential fatty acids various peripheral tissues. Postmortem studies indicate similar reductions in essential fatty acids in the brain. However, the use of magnetic resonance spectroscopy (MRS) has provided an opportunity to examine aspects of membrane biochemistry in vivo in the living brain. MRS is a powerful, albeit complex, noninvasive quantitative imaging tool that offers several advantages over other methods of in vivo biochemical investigations. It has been used extensively in investigating brain biochemistry in schizophrenia. Phosphorus MRS (31P MRS) can provide important information about neuronal membranes, such as levels of phosphomonoesters that reflect the building blocks of neuronal membranes and phosphodiesters that reflect breakdown products. 31P MRS can also provide information about bioenergetics. Studies in patients with chronic schizophrenia as well as at first episode prior to treatment show a variety of alterations in neuronal membrane biochemistry, supportive of the membrane hypothesis of schizophrenia. Below, we will briefly review the principles underlying 31P MRS and findings to date. Magnetic resonance spectroscopy (MRS) is a powerful, albeit complex, imaging tool that permits investigation of brain biochemistry in vivo. It utilizes the magnetic resonance imaging hardware. It offers several advantages over other methods of in vivo biochemical investigations. MRS is noninvasive, there is no radiation exposure, does not require the use of tracer ligands or contrast media. Because of it is relatively benign, repeated measures are possible. It has been used extensively in investigating brain biochemistry in schizophrenia.     

Evaluation of cardiac energetics by non-invasive 31P magnetic resonance spectroscopy

Alterations in myocardial energy metabolism have been implicated in the pathophysiology of cardiac diseases such as heart failure and diabetic cardiomyopathy. ³¹P magnetic resonance spectroscopy (MRS) is a powerful tool to investigate cardiac energetics non-invasively in vivo, by detecting phosphorus (³¹P)-containing metabolites involved in energy supply and buffering. In this article, we review the historical development of cardiac ³¹P MRS, the readouts used to assess cardiac energetics from ³¹P MRS, and how ³¹P MRS studies have contributed to the understanding of cardiac energy metabolism in heart failure and diabetes.This article is part of a Special issue entitled Cardiac adaptations to obesity, diabetes and insulin resistance, edited by Professors Jan F.C. Glatz, Jason R.B. Dyck and Christine Des Rosiers.     

连续提取和液体磷核磁共振表征太湖梅梁湾沉积物中磷的剖面分布

应用连续提取法(SMT)和液体磷核磁共振(³¹PNMR)技术研究了太湖北部梅梁湾沉积物中磷形态和组成的剖面变化。结果表明,铁/铝磷是沉积物中磷的主要形态,约占总磷含量的44.0-54.6%。总磷、无机磷、有机磷和铁/铝磷含量均随沉积深度增加呈降低趋势,至18cm以下略有增加,而钙磷却在柱样下部随沉积深度增加呈累积趋势。³¹PNMR显示,沉积物磷主要由正磷酸盐(72.0-99.2%)和磷酸单酯(0.8-25.9%)构成,磷酸二酯、膦酸盐和焦磷酸盐的相对含量非常低,分别为1.0%、0.4-1.0%和 0.1%。正磷酸盐含量在沉积物表层9cm内减少了65%,9cm以下波动变化,但总体呈降低趋势。这些特征表明沉积物中磷对梅梁湾上覆水体具有强烈的释放潜力,是太湖富营养化发生的重要因素。     

31P saturation transfer spectroscopy predicts differential intracellular macromolecular association of ATP and ADP in skeletal muscle

The kinetics of phosphoryl exchange involving ATP and ADP have been investigated successfully by in vivo ³¹P magnetic resonance spectroscopy using magnetization transfer. However, magnetization transfer effects seen on the signals of ATP also could arise from intramolecular cross-relaxation. This relaxation process carries information on the association state of ATP in the cell. To disentangle contributions of chemical exchange and cross-relaxation to magnetization transfer effects seen in ³¹P magnetic resonance spectroscopy of skeletal muscle, we performed saturation transfer experiments on wild type and double-mutant mice lacking the cytosolic muscle creatine kinase and adenylate kinase isoforms. We find that cross-relaxation, observed as nuclear Overhauser effects (NOEs), is responsible for magnetization transfer between ATP phosphates both in wild type and in mutant mice. Analysis of ³¹P relaxation properties identifies these effects as transferred NOEs, i.e. underlying this process is an exchange between free cellular ATP and ATP bound to slowly rotating macromolecules. This explains the β-ATP signal decrease upon saturation of the γ-ATP resonance. Although this usually is attributed to β-ADP ↔ β-ATP phosphoryl exchange, we did not detect an effect of this exchange on the β-ATP signal as expected for free [ADP], derived from the creatine kinase equilibrium reaction. This indicates that in resting muscle, conditions prevail that prevent saturation of β-ADP spins and puts into question the derivation of free [ADP] from the creatine kinase equilibrium. We present a model, matching the experimental result, for ADP ↔ ATP exchange, in which ADP is only transiently present in the cytosol.     

Application of nuclear magnetic resonance spectroscopy to analysis of ethanol fermentation kinetics in yeasts and bacteria

Nuclear Magnetic Resonance (NMR) spectroscopy is proving to be a very valuable technique for characterizing the metabolic status of a range of microbial fermentations. This non-invasive method allows us not only to determine the presence of particular metabolites, but also to monitor reaction rates, enzyme activities and transport mechanisms in vivo. Despite the low levels of the carbon-13 isotope (1.1%), natural-abundance ¹³C-NMR studies have proven useful in monitoring the progress of various fermentation processes. Furthermore, ³¹P-NMR can provide noninvasive information relating to cellular metabolism, and on the energy status of the cells. This results from the facility with NMR to identify various nucleotide phosphates and other energy-rich compounds in the cell, as well as to characterize changes in the intracellular pH from the chemical shifts of internal phosphate and other phosphorylated intermediates. In this review, we will summarize the use of NMR as an analytical tool in biotechnology and also discuss examples that illustrate how NMR can be used to obtain significant information on the characteristics of ethanol fermentations in both yeasts and bacteria.     

A new horizon of DNP technology: application to in-vivo 13C magnetic resonance spectroscopy and imaging

Dynamic nuclear polarization (DNP) is an emerging technique for increasing the sensitivity (>10,000-fold) of magnetic resonance spectroscopy and imaging (MRSI), in particularly for low-γ nuclei. DNP methodology is based on polarizing nuclear spins in an amorphous solid state at low temperature (ca. 1 K) through coupling of the nuclear spins with unpaired electron spins that are added to the sample via an organic free radical. In an amorphous solid state, the high electron spin polarization can be transferred to the nuclear spins by microwave irradiation. While this technique has been utilized in solid-state research for many years, it is only recently that dissolution methods and the required hardware have been developed to produce the high nuclear polarization provided by DNP to produce injectable hyperpolarized solutions suitable for in vivo studies. It has been applied to a number of ¹³C-labeled cell metabolites in biological systems and their real-time metabolic conversion has been imaged. This review focuses briefly on the DNP methodology and the significant molecules investigated to date in preclinical cancer models, in terms of their downstream metabolism in vivo or the biological processes that they can probe. In particular, conversion between hyperpolarized ¹³C-labeled pyruvate and lactate, catalyzed by lactate dehydrogenase, has been shown to have a number of potential applications such as diagnosis, staging tumor grade, and monitoring therapy response. Strategies for making this technique more viable to use in clinical settings have been discussed.