Hepatic lipid composition analysis using 3.0-T MR spectroscopy in a steatotic rat model

Purpose

To investigate the feasibility of in vivo assessment of hepatic lipid composition using 3.0-T proton magnetic resonance spectroscopy (¹H-MRS) in a steatotic rat model and compare it to histopathological and biochemical assessment.

Materials and Methods

Hepatic steatosis was induced by feeding rats with a methionine/choline-deficient (MCD) diet for 1, 2, 3, 5 or 7 weeks (n=5 per group). At the end of the diet period, ¹H-MRS of the liver was performed, and rats were sacrificed for histopathological and biochemical assessment of the liver. Spectra were acquired in a single voxel (1.2 cc) using a point-resolved spectroscopic sequence with TE/TR=35/2000 ms and 64 signal acquisitions. From the MR spectra, peak area ratios were calculated to estimate hepatic lipid composition.

Results

During MCD diet periods, hepatic steatosis significantly increased on histopathology (P<.001). The ¹H-MRS measurements of total hepatic fat content [1.3/(1.3+4.65) ppm] correlated strongly with histological macrovesicular hepatic steatosis (r=0.93, P<.001) and with the biochemical total hepatic fatty acids (r=0.94, P<.001). Total unsaturated fatty acids [TUFA, 5.4/(1.3+4.65) ppm] estimated with ¹H-MRS strongly correlated with the biochemical unsaturated fatty acids (r=0.90, P<.001). Polyunsaturated fatty acids [PUFA, 2.8/(1.3+4.65) ppm] estimated with ¹H-MRS strongly correlated with biochemical PUFA (r=0.91, P<.001). The proportion of total unsaturated fatty acids relative to the amount of total fatty acids (rTUFA, 5.4/1.3ppm) measured with ¹H-MRS strongly correlated with the biochemical amount of unsaturated relative to total hepatic fatty acids (r=0.81, P<.001). The proportion of PUFA relative to the amount of total fatty acids (rPUFA, 2.8/1.3 ppm) measured with ¹H-MRS correlated with the biochemical amount of PUFA relative to total fatty acids (r=0.59, P=0.005,) and with the biochemical amount of omega-6 PUFA relative to total fatty acids (r=0.73, P<.001).PUFA at ¹H-MRS correlated with the histopathologically assessed degree of lobular inflammation in the liver (r=0.57, P=.001).

Conclusion

3.0T ¹H-MRS is able to measure poly- and unsaturated hepatic fatty acids and this strongly correlates with biochemical assessment. This study provides evidence that 3.0-T ¹H-MRS is a noninvasive technique to assess hepatic lipid composition.     

冷端温度对无极灯253.7nm共振谱线的影响

无极灯是一种长寿命、低汞害、无频闪的新型电光源,其光效在很大程度上取决于253.7nm共振谱线的辐射效率。通过原子发射光谱分析,实验研究了冷端温度对253.7nm共振谱线的影响规律。研究发现,253.7nm共振谱线的辐射效率随冷端温度变化近似呈正态分布,即无极灯工作存在一个最佳冷端温度。运用气体放电理论对实验结果进行了定性分析,对无极灯光效的提高具有指导意义。     

孔雀石绿-锌(Ⅱ)-牛血清白蛋白的共振光散射及其分析应用

基于牛血清白蛋白(BSA)使孔雀石绿(MG)-锌(Ⅱ)配合物体系的共振光散射光谱(RLS)信号增强,建立了一种测定痕量蛋白质的新方法。探讨了pH、MG浓度、金属离子浓度、共存物质等因素对共振光散射强度的影响。在优化实验条件下,RLS强度与BSA浓度的线性范围为0.1—25μg/mL,检出限0.06μg/mL,运用该方法对合成样品加标回收测定,结果满意。     

分子光谱法研究硫普罗宁修饰的CdTe量子点与血红蛋白相互作用

以N-(2-巯基丙酰基)-甘氨酸(硫普罗宁,TP)为稳定剂,采用水相法合成了荧光较好的水溶性CdTe量子点(TP-CdTe QDs)。本文通过共振瑞利散射光谱(RRS)、荧光光谱(FL)和紫外光谱(UV-Vis),探讨了TP-CdTe QDs与血红蛋白通过静电引力相互作用的机理.研究发现TP-CdTe QDs与血红蛋白通过静电引力相互作用以后,TP-CdTe QDs荧光猝灭发生猝灭同时荧光光谱发生蓝移,体系的共振瑞利散射光谱强度增大.血红蛋白通过静态猝灭,动态猝灭和光诱导电子转移的方式猝灭TP-CdTeQDs的荧光。同时对体系共振瑞利散射增强的原因进行了讨论。     

硫脲21A激发态扭曲几何结构的共振拉曼光谱和理论研究

获得了硫脲在水和乙腈溶液中A吸收带的共振拉曼光谱,通过B3LYP/6-311++G(3df,3pd)和RCIS/6-311++G(3df,3pd)分别对硫脲的电子跃迁和2¹A 激发态鞍点结构进行了研究．对共振拉曼光谱进行了归属,并通过含时波包理论对吸收光谱和共振拉曼光谱进行拟合,结果表明硫脲动态结构特征主要沿着：C=S伸缩振动ν₆(|△|=0.95)、H₅N₃H₆+H₈N₄H₇弯曲振动ν₅(|△|=0.19)、NCN对称伸缩振动+C=S伸缩振动+N₃H₆+H₈N₄弯曲振动ν₄(|△|=0.18)．ν₁₅倍频2ν₁₅和4ν₁₅强度主要归因于ν₁₅激发态频率的改变而不是简正模位移量的变化．对S=CN₂面外变形振动ν₁₅倍频出现的机理进行了探究,结果表明Franck-Condon区域势能面鞍点是标准A项共振拉曼散射里的二次声子机制的驱动力,导致碳原子中心的锥形化,并使硫脲在2¹A激发态发生几何结构扭曲.     

Nano-structured Fabry–Pérot resonators in neutron optics & tunneling of neutron wave-particles

Correlated to the quantum mechanics wave-particle duality, the optical analogy between electromagnetic waves and cold neutrons manifests itself through several interference phenomena particularly the so called Frustrated Total Reflection i.e., the tunneling process in Fabry–Pérot nano-structured cavities. Prominent resonant situations offered by this configuration allow the attainment of numerous fundamental investigations and surface-interface studies as well as to devise new kinds of neutron optics devices. This review contribution reports such possibilities in addition to the recently observed peculiar Goos–Hänchen longitudinal shift of neutron wave-particles which was predicted by Sir Isaac Newton as early as 1730.     

Analysis of the composition of the passive film on iron under pitting conditions in 0.05 M NaOH/NaCl using Raman microscopy in situ with anodic polarisation and MCR‐ALS

The composition of the surface film formed on pure iron was investigated in a solution of 0.05 M NaOH and 0.05 M NaCl. Raman spectra of the film were recorded in situ during anodic polarisation over the passive region after addition of the NaCl to the electrolyte, under conditions of preresonance enhancement using excitation at 636.4 nm. Multivariate curve resolution with alternating least squares analysis was applied to the spectra to measure the relative amounts of different iron oxide and oxyhydroxides in the film at different potentials. The water content was also determined in this way from Raman spectra recorded using excitation at 514.5 nm. It was found that the composition of the film and the amount of incorporated water were influenced by the applied anodic potential. The results show that stable pitting can occur when the composition changes from the primary constituents β‐FeOOH and Green Complex (a hydrated, amorphous magnetite) with smaller amounts of γ‐Fe₂O₃ and γ‐FeOOH, to δ‐FeOOH and Green Complex, simultaneously with a reduction in water content. These changes result in conditions that favour the rate of localised breakdown of the film by Cl⁻ ions over the rate of repassivation by water in the passive film. Copyright © 2011 John Wiley & Sons, Ltd.     

吖啶红-SLS体系共振瑞利散射法测定蛋白质

研究了吖啶红染料与蛋白质的结合反应。在十二烷基磺酸钠存在下及pH2.90的柠檬酸NaOH介质中,蛋白质与吖啶红形成复合物,使最大波长392nm的共振光散射光谱得到加强,根据其共振光散射的增强程度,可用于蛋白质的定量测定。十二烷基磺酸钠的加入,使灵敏度提高11倍,牛血清白蛋白、γ球蛋白的线性范围分别为0.03～0.7mg/L、0.05～1.3mg/L,检出限分别为6.4μg/L、10.8μg/L。用于人血清、牛奶、豆浆、尿液中总蛋白质的测定,结果与经典的考马斯亮蓝G 250法一致。     

Existence of solutions for a class of noncooperative elliptic systems

We establish the existence of a nontrivial solution for a class of noncooperative elliptic systems with nonlinearities of superlinear growth. Moreover, if there is resonance, we also find at least a solution. All results are obtained by the minimax methods in critical point theory.