Interactions of acetylcholinesterase with salvianolic acid B and rosmarinic acid from Salvia miltiorhiza water extract investigated by NMR relaxation rate

In order to understand whether the ameliorating effect on old ages memory disorder by the root of Salvia miltiorhiza is related to the acetylcholinesterase （ACHE） inhibition, two main ingredients, salvianolic acid B （1） and rosmarinic acid （2）, which were isolated from S. miltiorhiza water extract, were investigated in vitro by NMR relaxation rate in this work. The results showed that the proton selective relaxation rates and the molecular rotational correlation time of proton pairs for compounds 1 and 2 increased significantly by adding of AChE in mixing solution. The study reveals that the two compounds might bind to the enzyme and have ACHE inhibitory effect, which could contribute to the ameliorating effect at some extent on old ages memory disorder.

Investigation on Positive Correlation of Increased Brain Iron Deposition with Cognitive Impairment in Alzheimer Disease by Using Quantitative MR R2' Mapping

Brain iron deposition has been proposed to play an important role in the pathophysiology of Alzheimer disease（AD）.The aim of this study was to investigate the correlation of brain iron accumulation with the severity of cognitive impairment in patients with AD by using quantitative MR relaxation rate R2＇ measurements.Fifteen patients with AD,15 age-and sex-matched healthy controls,and 30 healthy volunteers underwent 1.5T MR multi-echo T2 mapping and T2＊ mapping for the measurement of transverse relaxation rate R2＇（R2＇=R2＊-R2）.We statistically analyzed the R2＇ and iron concentrations of bilateral hippocampus（HP）,parietal cortex（PC）,frontal white matter（FWM）,putamen（PU）,caudate nucleus（CN）,thalamus（TH）,red nucleus（RN）,substantia nigra（SN）,and dentate nucleus（DN） of the cerebellum for the correlation with the severity of dementia.Two-tailed t-test,Student-Newman-Keuls test（ANOVA） and linear correlation test were used for statistical analysis.In 30 healthy volunteers,the R2＇ values of bilateral SN,RN,PU,CN,globus pallidus（GP）,TH,and FWM were measured.The correlation with the postmortem iron concentration in normal adults was analyzed in order to establish a formula on the relationship between regional R2＇ and brain iron concentration.The iron concentration of regions of interest（ROI） in AD patients and controls was calculated by this formula and its correlation with the severity of AD was analyzed.Regional R2＇ was positively correlated with regional brain iron concentration in normal adults（r=0.977,P0.01）.Iron concentrations in bilateral HP,PC,PU,CN,and DN of patients with AD were significantly higher than those of the controls（P0.05）;Moreover,the brain iron concentrations,especially in parietal cortex and hippocampus at the early stage of AD,were positively correlated with the severity of patients＇ cognitive impairment（P0.05）.The higher the R2＇ and iron concentrations were,the more severe the cognitive impairment was.Regional R2＇ and iron concentration in parietal cortex and hippocampus were positively correlated with the severity of AD patients＇ cognitive impairment,indicating that it may be used as a biomarker to evaluate the progression of AD.

Regulation of MRI contrast and cellular retention time by cellular interfacial distribution of Gd agents:Implications for stem cell tracking

Human mesenchymal stem cells(hMSCs)were labeled with Dotarem or(Gd-DOTA)2-EM7(EM7Gd2)via electroporation(EP).Cellular transmission electron microscopy(TEM)reveals free distribution of Gd agents and formation of EM7Gd2 clusters in the cytosol.Cellular magnetic resonance imaging(MRI)reveals that the free Gd agents induce MRI signal enhancement effect due to its fast exocytosis and subsequent interaction with intercellular water molecules.The EM7Gd2 clusters exhibits a longer intracellular retention time and induce a persistent MRI signal reduction effect.The cellular MRI results are interpreted by taking into account both T1 and T2 relaxation rates and their correlation with cellular binding structures of Dotarem and EM7Gd2.

Transient electromagnetically induced transparency spectroscopy of^(87)Rb atoms in buffer gas

We study the transient response dynamics of^(87)Rb atomic vapor buffered in 8 torr Ne gas through an electromagnetically induced transparency configured inΛ-scheme.Experimentally,the temporal transmission spectra versus probe detuning by switching on and off the coupling one show complex structures.The transmitted probe light intensity drops to a minimum value when the coupling light turns off,showing a strong absorption.Even at the moment of turning on the coupling light at a subsequent delayed time,the atomic medium shows a fast transient response.To account for the transient switching feature,in the time-dependent optical Bloch equation,we must take the transverse relaxation dephasing process of atomic vapor into account,as well as the fluorescence relaxation along with the optical absorption.This work supplies a technique to quantify the transverse relaxation time scale and to sensitively monitor its variation along the environment by observing the transient dynamics of coherent medium,which is helpful in characterizing the coherent feature of the atomic medium.

Difference Analysis of MRI Apparent Diffusion Coefficient and R_(2)^(*)Value Between Small Hepatocellular Carcinoma and Cirrhosis Nodules

Objective:To investigate the differences of apparent diffusion coefficient and transverse relaxation rate(R_(2)^(*))in magnetic resonance imaging(MRI)between micro hepatocellular carcinoma and nodules of cirrhosis.Method:The clinical data of 68 patients with micro hepatocellular carcinoma(76 lesions)and 45 patients with nodular cirrhosis(48 lesions)were retrospectively analyzed.Diffusion weighted imaging and R_(2)^(*)imaging were performed on all patients.The differences of apparent diffusion coefficient and R_(2)^(*)values in patients with micro hepatocellular carcinoma and nodular cirrhosis were compared.Receiver operating characteristic(ROC)curves were drawn to evaluate the diagnostic efficacy of apparent diffusion coefficient values and R_(2)^(*)values for microhepatocellular carcinoma.Result:Compared with nodules of cirrhosis,the mean apparent diffusion coefficient and R_(2)^(*)value of micro-hepatocellular carcinoma were significantly decreased(P<0.05).The diagnosis threshold of apparent diffusion coefficient is at 1.35×10^(-3)mm^(2)/s,and the sensitivity for the diagnosis of micro-hepatocellular carcinoma was 80.88%,and the specificity was 91.11%,and the corresponding area under the ROC curve was 0.88;The diagnostic threshold for R_(2)^(*)value was at 53.96 Hz,and the sensitivity for the diagnosis of small hepatocellular carcinoma was 91.18%,and the specificity was 77.78%,and the corresponding area under the ROC curve was 0.84.Conclusion:MRI apparent diffusion coefficient value and R_(2)^(*)value can be used to differentiate and diagnose micro hepatocellular carcinoma and nodules of cirrhosis,in which the apparent diffusion coefficient of nodules of cirrhosis was less than 1.35×10^(-3)mm^(2)/s,R_(2)^(*)values were lower than 53.96 Hz may indicate the occurrence of nodular canceration.

Calculation of vibrational energy transition rates in acoustic relaxation processes for excitable gas molecules

To research the correlation between vibrational energy transition rates and acoustic relaxation processes in excitable gases, the vibrational relaxation theory provided by Tanczos [J. Chem. Phy3. 25, 439 （1956）] is applied to calculate the energy transition rates of Vibrational- Vibrational （V-V） and Vibrational-Translational （V-T） energy transfer in gas mixtures. The results of calculation for the multi-relaxation processes in various gas mixtures, consisting of carbon dioxide, methane, chlorine, nitrogen, and oxygen at room temperature, demonstrate that the acoustic energy stagnated in every vibrational mode is coupled with each other through V-V energy exchanges. The vibrational excitation energy will relax through the V-T de-excitation path of the lowest mode because of its fastest V-T transition rate, resulting in that only one absorption peak can be measured for most of excitable gas mixtures. Thus, an effective model is provided to analyze how the vibrational energy transition rates affect the characteristics of acoustic relaxation processes and acoustic propagation in excitable gas mixtures.