Quantifying the blood oxygenation level dependent effect in cerebral blood volume-weighted functional MRI at 9.4T.

In cerebral blood volume (CBV)-weighted functional MRI (fMRI) employing superparamagnetic contrast agent, iron dose and blood oxygenation level dependent (BOLD) contamination are two important issues for experimental design and CBV quantification. Both BOLD and CBV-weighted fMRI are based upon the susceptibility effect, to which spin-echo and gradient-echo sequences have different sensitivities. In the present study, CBV-weighted fMRI was conducted using spin-echo and gradient-echo sequences at 9.4T by systematically changing the doses of contrast agent. Results suggest that BOLD contamination is a significant component in CBV-weighted fMRI at high field, particularly when relatively low dose of contrast agent is administered. A mathematical model was developed to quantify the extravascular (EV) BOLD effect. With a TE of 35 ms, the EV BOLD effect was estimated to account for 76+/-12% of the observed spin-echo fMRI signal at 9.4T. These data suggest that correcting BOLD effect may be necessary for accurately quantifying activation-induced CBV changes at high field.     

Phase-sensitive cardiac tagging--REALTAG.

Fully inverting spins, instead of merely saturating them, provides superior contrast for tagging procedures. The resulting improvement in tag contrast-to-noise ratio (CNR) yields higher-precision tag detection. Also, thinner slices and hence reduced tag separations can be employed, providing displacement and strain measurements with better spatial resolution. Alternatively, the improved tag contrast can be used to obtain cine images covering a greater portion of the cardiac cycle. The use of standard magnitude reconstruction for images of these inversion tags causes rectification of the negative-valued signals from the tags, confounding the image interpretation. Therefore, a phase-sensitive reconstruction scheme of the inverted tags must be employed. Here we demonstrate the implementation of inverted tags with phase-sensitive reconstruction in a ramped-flip-angle, steady-state free precession (SSFP) sequence.     

对药品市场营销中代理环节监督管理的思考

随着我国药品分销市场的对外放开,传统的批发零售经营方式发生了根本变化,代理配送制将成为医药流通的主要方式.药监工作人员要准确掌握药品分销市场的现状及发展趋势,抓好药品市场营销中代理环节的监督管理.     

The effect of observation time and contrast on visual acuity

Background: Field studies of the duration of fixation during daytime driving find that it is about 0.2 seconds on average. Thus, the time available to read traffic signs is often limited. There are other circumstances where time to read alphanumeric messages is limited. Data relating time of observation are needed for purposes of ergonomic design as the data available in the literature are limited and uncertain. Method: Visual acuity was measured using Landolt rings in negative contrast, which were presented on a computer screen with a background luminance of 32 cd/m2 for durations that varied between two and 0.02 seconds at three different contrasts. Resulte: Visual acuity depends on the log of the light dose reduced by a factor that may be related to absorption of the light by the eye media. For young observers, it was found that: VA = 0.57 (log C t) + 1.705, where C is the contrast and is expressed as δL/L, where δL is the difference between target and background luminances in cd/m2 and t is the observation time in seconds. Conclusion: This formula or the functions fitted to the data obtained can be used to calculate the increase in target size needed to allow for short observation times.     

顺糖氨铂(Ⅱ)的合成

以氯铂酸钾为原料，经硫酸氨铂(Ⅱ)中间体制得抗肿瘤药物顺糖氨铂(Ⅱ)，操作简便，总收率46．1％。     

离子型与非离子型MR对比剂对肝脏病变的增强效果比较

目的　对比离子型钆喷酸葡胺 (Gd -DTPA)和非离子型钆双胺MR对比剂 (Gd -DTPA -BMA)在肝脏病变手推团注多时相增强扫描中的增强效果。方法　 5 8例肝脏疾病患者 (男 3 1例 ,女 2 7例 ,年龄 3 0～ 77岁 )分 2组 ,第 1组 :3 0例 (男 16例 ,女 14例 ) ,采用Gd -DTPA -BMA。第 2组 :2 8例 (男 17例 ,女 11例 ) ,采用Gd -DTPA。行MR手推团注多时相增强扫描。结果　Gd -DTPA -BMA组 :增强效果满意者 2 3例 (77% ) ,增强效果一般者 6例 (2 0 % ) ,增强效果差者 1例 (3 % )。Gd -DTPA组 :增强效果满意者 2 2例(79% ) ,增强效果一般者 6例 (2 1% )。结论　在肝脏疾病MR手推团注多时相增强扫描中 ,Gd -DTPA -BMA和Gd -DTPA均可达到满意的增强效果 ,安全及有效性两者无显著性差异。Gd -DTPA -BMA粘滞度小 ,利于快速推注。     

二乙基二硫代氨基甲酸钠驱镍作用的实验研究

本文用大鼠研究了带-SH基的二乙基二硫代氨基甲酸钠(Dithiocarb,简称Na-DDC或称铜试剂)和不带-SH基的新螯合剂(H-73-10)的驱镍作用。结果表明,Na-DDC对羰基镍(Ni(CO)_4〕的驱镍作用明显优于H-73-10;与此相反,H-73-10对硝酸镍〔Ni(NO_3)_2〕染毒大鼠的驱镍作用却明显优于Na-DDC。     

新型麻醉药异丙酚的氧化动力学

采用高效液相色谱法测定了异丙酚在不同温度下及其甲醇 水（Ｖ∶Ｖ＝７０∶３０）混合溶液在不同ｐＨ值下的反应速率常数，并求出了异丙酚氧化反应的活化能，结果表明ｐＨ值与温度对异丙酚的氧化动力学均有影响     

CMSS-VEPs: Contrast modulated steady state visual evoked potentials: Its neuronal origin and clinical use

CMSS-VEPs are presented as a sensitive, non-invasive functional investigation technique of the visual function, applicable in clinical practice. New improvements of the technique are presented. The underlying neuronal mechanisms are discussed. The clinical use is illustrated in a case of optic neuritis.     

Selective modification at the N-terminal region of human growth hormone that shows antagonistic activity

A new analogue of recombinant human growth hormone (hGH), hGH des(1–6,14) was expressed in Escherichia coli, refolded and purified to homogeneity. The mutation decreased the hormone's ability to bind lactogenic and somatogenic receptors through its site 1, and almost completely abolished its ability to bind these receptors through site 2, as evidenced by both binding and gel-filtration experiments. More specifically, the binding to prolactin receptors (PRLRs) from various species or their soluble recombinant extracellular domains (ECDs) was decreased 1.5–4-fold, whereas the binding to hGH receptor (hGHR) was decreased 10–85-fold. These changes caused an almost total loss of hormone agonistic activity in several in vitro bioassays and subsequently, the hGH des(1–6,14) analogue acquired antagonistic properties. This antagonistic activity was dependent upon modification of site 1. In those cases in which the binding was reduced only slightly, e.g. binding to rabbit PRLRs, hGH des(1–6,14) acted as a strong antagonist, whereas in others in which the binding of site 1 was reduced to a higher degree, such as other PRLRs and, in particular, hGHR, the antagonistic activity was correspondingly weaker. Circular dichroism spectra of the analogue suggested that these changes do not result from a decrease in overall -helix content, but rather from minor local structural modifications at the N-terminus.