Magnetic resonance spectroscopy identifies neural progenitor cells in the live human brain

The identification of neural stem and progenitor cells (NPCs) by in vivo brain imaging could have important implications for diagnostic, prognostic, and therapeutic purposes. We describe a metabolic biomarker for the detection and quantification of NPCs in the human brain in vivo. We used proton nuclear magnetic resonance spectroscopy to identify and characterize a biomarker in which NPCs are enriched and demonstrated its use as a reference for monitoring neurogenesis. To detect low concentrations of NPCs in vivo, we developed a signal processing method that enabled the use of magnetic resonance spectroscopy for the analysis of the NPC biomarker in both the rodent brain and the hippocampus of live humans. Our findings thus open the possibility of investigating the role of NPCs and neurogenesis in a wide variety of human brain disorders.     

Magnetic resonance imaging of biological specimens by electron paramagnetic resonance of nitroxide spin labels

Electron paramagnetic resonance imaging was demonstrated on two plant species, Apium graveolens and Coleus blumei. This was accomplished by soaking stems of these plants in the paramagnetic nitroxide imaging agent 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl. The experiments were accomplished at L-band frequency (1.4 to 1.9 gigahertz) with single-turn, flat-loop surface coils. One-dimensional imaging spectra were diagnostic of capillary structure and long-term stability.     

Comment on "Magnetic resonance spectroscopy identifies neural progenitor cells in the live human brain"

Manganas et al. (Reports, 9 November 2007, p. 980) used nuclear magnetic resonance spectroscopy to identify a biomarker of neural progenitor cells. However, their analysis relies on spectral processing methods that are known to be problematic. Absent detection using alternate methods of spectrum analysis or controls to quantify the false discovery rate, their conclusions may be premature.     

MRI诊断双侧基底节区对称性分水岭脑梗死

目的：探讨双侧基底节区对称性分水岭性脑梗死(CWI)的病因与机理、MRI特征。方法：回顾性分析12例经MRI及临床证实的双侧基底节区对称性CWI的临床资料及MRI表现。结果：12例的病因中以严重低血压及低血容量为主，MRI表现为双侧基底节区对称性T1WI为低，T2WI为高信号，信号均匀，占位不明显，加强扫描无强化。结论：双侧基底节区对称性CWI病因主要为严重低血压及低血容量。MRI能较早及敏感地显示其变化，其与一些好发于基底节区病变的MRI表现相似，鉴别时须结合临床资料。     

汞对水生动物酶活性影响与机理的研究进展

汞是一种以多种形式、广泛而持久地污染水体的重金属,汞及其化合物的毒性较大,可通过食物链富集进入人体和其他动物体包括水生动物,对机体健康造成严重威胁,其中水生动物酶活性是最敏感的标志物之一.重点综述汞对水生动物酶活性影响与机理研究的新进展,旨在更好地深入研究、理解汞对水生动物的影响、机理及防治,为采取更加积极有效的控制和防治措施、保护水生生态环境提供参考.     

Long-term activity recording in small aquatic animals

We have built an activity-recording device based on the principle of detecting slight changes in the heat conductance of an aquatic environment by means of a thermistor. A major advantage of the device is that it can be used with a simple event recorder, thus combining high sensitivity with low cost. The equipment has been tested with automatic mechanical stimulation, and has been used for long-term recording of the swimming of small marine crustaceans. Problems of stability and reliability have been solved, and potential applications of the device seem widespread.     

Echo-planar imaging: magnetic resonance imaging in a fraction of a second

Progress has recently been made in implementing magnetic resonance imaging (MRI) techniques that can be used to obtain images in a fraction of a second rather than in minutes. Echo-planar imaging (EPI) uses only one nuclear spin excitation per image and lends itself to a variety of critical medical and scientific applications. Among these are evaluation of cardiac function in real time, mapping of water diffusion and temperature in tissue, mapping of organ blood pool and perfusion, functional imaging of the central nervous system, depiction of blood and cerebrospinal fluid flow dynamics, and movie imaging of the mobile fetus in utero. Through shortened patient examination times, higher patient throughput, and lower cost per MRI examination, EPI may become a powerful tool for early diagnosis of some common and potentially treatable diseases such as ischemic heart disease, stroke, and cancer.     

Functional magnetic resonance imaging in medicine and physiology

Magnetic resonance imaging (MRI) is a well-established diagnostic tool that provides detailed information about macroscopic structure and anatomy. Recent advances in MRI allow the noninvasive spatial evaluation of various biophysical and biochemical processes in living systems. Specifically, the motion of water can be measured in processes such as vascular flow, capillary flow, diffusion, and exchange. In addition, the concentrations of various metabolites can be determined for the assessment of regional regulation of metabolism. Examples are given that demonstrate the use of functional MRI for clinical and research purposes. This development adds a new dimension to the application of magnetic resonance to medicine and physiology.     

Quantum dots for live cells, in vivo imaging, and diagnostics

Research on fluorescent semiconductor nanocrystals (also known as quantum dots or qdots) has evolved over the past two decades from electronic materials science to biological applications. We review current approaches to the synthesis, solubilization, and functionalization of qdots and their applications to cell and animal biology. Recent examples of their experimental use include the observation of diffusion of individual glycine receptors in living neurons and the identification of lymph nodes in live animals by near-infrared emission during surgery. The new generations of qdots have far-reaching potential for the study of intracellular processes at the single-molecule level, high-resolution cellular imaging, long-term in vivo observation of cell trafficking, tumor targeting, and diagnostics.     

Circadian changes in enzyme concentration account for rhythm of enzyme activity in gonyaulax

A circadian rhythm in the activity of luciferase is partly responsible for rhythmic bioluminescence in the dinoflagellate alga Gonyaulax polyedra. The cyclic activity of this enzyme can be attributed to a corresponding rhythm in the concentration of immunologically reactive luciferase protein. Hence protein turnover (synthesis or degradation or both) is used by the endogenous clock to control the daily rhythm of bioluminescence.     

饵料中添加芽孢杆菌BC26对刺参幼参消化酶、免疫反应和抗病力的影响

将浓度为105、107、109CFU/g(饵料)的芽孢杆菌BC26添加到基础饵料中,用每一浓度的饵料投喂一组刺参幼参(1.374 g±0.558 g),对照组投喂基础饵料,每组均设3个平行,试验在12个盛有100 L过滤海水的塑料桶中进行,每桶放50头幼参,饲养试验共进行45 d。试验结束后,分析芽孢杆菌BC26对幼参肠道消化酶活力、免疫反应和抗病力的影响。结果表明:投喂芽孢杆菌BC26饵料的各组幼参肠道中的胰蛋白酶、脂肪酶活力,以及体腔液中的酚氧化酶、总一氧化氮合酶活力均极显著高于对照组(P<0.01);投喂浓度为107、109CFU/g(饵料)的芽孢杆菌BC26组幼参体腔细胞的吞噬活力极显著高于对照组(P<0.01);用病原菌灿烂弧菌NB13攻毒各组幼参,投喂芽孢杆菌BC26组的幼参发病率和死亡率明显低于对照组。研究表明,饵料中添加芽孢杆菌BC26可促进刺参消化和增强免疫功能,并提高其抗病力。     

反胶束体系的光密度与酶活性测定

以正庚烷-正丁醇-大豆卵磷脂配制反胶束,做了增溶不同量Tris—HCl缓冲液的试验．结果表明：增溶不同水量的反胶束体系稳定性不一样,每3mL增溶40-90μL缓冲液的反胶柬体系光密度在0—300s内不断变化,透明澄清的稳定反胶束体系分布在每3mL增溶0～40μL及90～130μL2个区间．增溶水量较少时,反胶束增溶含蛋白质与不含蛋白质水相的体系之间存在差别．在水-正庚烷-正丁醇-大豆卵磷脂反胶束体系中未发现核糖核酸酶A1（RNase A1）的超活性．     

Accurate temperature imaging based on intermolecular coherences in magnetic resonance

Conventional magnetic resonance methods that provide interior temperature profiles, which find use in clinical applications such as hyperthermic therapy, can develop inaccuracies caused by the inherently inhomogeneous magnetic field within tissues or by probe dynamics, and work poorly in important applications such as fatty tissues. We present a magnetic resonance method that is suitable for imaging temperature in a wide range of environments. It uses the inherently sharp resonances of intermolecular zero-quantum coherences, in this case flipping up a water spin while flipping down a nearby fat spin. We show that this method can rapidly and accurately assign temperatures in vivo on an absolute scale.     

北乌头提取物对舞毒蛾体内酶活性的影响

采用系统溶剂法对北乌头甲醇提取物进行分离,用饲料混药法测定4种萃取物对舞毒蛾的胃毒毒力,测定了北乌头乙酸乙酯萃取物对舞毒蛾幼虫体内解毒酶、保护酶、消化酶活力的影响。试验结果表明:北乌头乙酸乙酯萃取物杀虫作用显著,为主要杀虫活性物质;舞毒蛾幼虫经北乌头乙酸乙酯萃取物亚致死浓度(LC_(20))处理后,其体内羧酸酯酶、谷胱甘肽S-转移酶和乙酰胆碱酯酶活性均表现为持续抑制,处理72 h,乙酰胆碱酯酶活力为对照的50.6%,抑制作用极显著(P0.01);超氧化物歧化酶、过氧化氢酶、过氧化物酶活性均表现为先激活后抑制,处理24 h,过氧化氢酶活力为对照的1.613倍,激活作用极显著(P0.01),处理72 h,超氧化物歧化酶活力为对照的84.2%,抑制作用极显著(P0.01);脂肪酶和淀粉酶活性均表现为持续抑制,处理72 h,脂肪酶活力为对照的53.9%,抑制作用极显著(P0.01);蛋白酶活性表现为先激活后抑制,处理24 h,蛋白酶活力为对照的1.431倍,激活作用极显著(P0.01),处理72 h,蛋白酶活力为对照的90.4%,抑制作用显著(P0.05)。综上,北乌头乙酸乙酯萃取物可影响舞毒蛾幼虫的解毒酶、保护酶及消化酶,扰乱其正常生理代谢。