T—2毒素提取分离方法的改进

本文报道从三线镰刀菌(Fusarium tricinctum)M-20大米培养物中提取分离T-2毒素的新方法.用70%乙醇渗漉得到粗毒素,经一次硅胶柱层析分离纯化,用苯:石油醚结晶和丙酮:正己烷重结晶,即可得到白色针状结晶.根据熔点、红外、质谱(FD-MS,EI-MS)H核磁共振谱及高效薄层等分析,确证此结晶为T-2毒素.气相色谱分析纯度为98.34～99.59%.本方法操作简便,经济实用.     

T—2毒素对小鼠小肠的早期毒性作用

本文报告了 T-2毒素所致小鼠小肠损伤及其修复过程。中毒后1h 所有隐窝中有丝分裂像消失,且大部分隐窝上皮细胞发生退行变;4h 大部分上皮细胞死亡;8及12h 隐窝消失的数目逐渐增多;16h 有丝分裂像在一些隐窝中开始重新少数出现,并逐渐增多;24h 几乎所有隐窝形态均正常。文献中尚无 T-2毒素所致早期中毒后1h 小肠损伤形态学的资料,故本文填补了这一空白。     

T—2毒素对肝脏脂质过氧化作用的体外效应

在体外观察了Ｔ－２毒素对大鼠及小鼠肝脏脂质过氧化的影响。结果表明，Ｔ－２毒素引起肝匀浆脂质过氧化物丙二醛及脂褐素含量降低，并且这种变化存在时间和剂量效应关系；不同剂量Ｔ－２毒素对肝匀浆总巯基、蛋白巯基以及非蛋白巯基无明显影响。     

T—2毒素对小鼠致癌作用的病理形态学观察

241只小鼠分别饮用不同浓度的T－2毒素水溶液7－18个月。病理形态学观察结果表明，T－2毒素有诱导小鼠发生肿瘤的作用。饮水中含T－2毒素0．05mg/kg可诱发雌性小鼠乳腺癌，发生率达35％，而对照小鼠仅为4％。饮水中含T－1毒素0．1mg/kg，可诱发雌性小鼠黄体瘤，发生率达10％，而对照小鼠为0％。     

生物样品中T—2毒素及其代谢产物的分离与分析

通过优化实验条件,建立了灵敏、专一、简便的生物样品中T-2毒素及其代谢产物的分离分析方法。灌流液、血、组织样品经XAD-2小柱提取,9∶1的甲醇水溶液洗脱,洗脱液浓缩后用N-七氟丁酰咪唑衍生化,电子捕获气相色谱进行检测。该法能有效地去除杂质干扰,毒素及产物的回收率大都在90%以上,最低检出限分别为(1～2.5)×10~(-11)g(CV%为5.5～9.8)。     

T—2毒素诱发哺乳动物细胞DNA单链断裂效应

用总洗脱时间为2h 的碱洗脱技术测定不同剂量~(60)Co-γ线照射后 L_(1210)细胞的 DNA 单链断裂,能获得与照射剂量呈直线关系的洗脱动力学曲线,剂量效应关系 r=-0.9986。0.1、1、10和100μg/ml 的 T-2毒索与哺乳动物细胞(L_(1210)和 HEL)作用3或24h均诱导轻度 DNA 单链断裂,相对 DNA 单链断裂度为11%～19%。     

T—2毒素急性中毒对大鼠左室心肌舒缩性能的影响

用颈动脉-左心室导管法,观察了乌拉坦麻醉大鼠致死量 T-2毒素静脉注射急性中毒后8h 内左心室舒缩性能及心率、心电图等指标的动态变化。其中,反映舒张性能的-dp/dt max、LVEDP、LVDP 降值及心电图缺血损伤性改变发生较早,一般在中毒后1～4h 开始,呈进行性加重,至4、5h,与对照组有显著或非常显著的差别国;心率和反映收缩性能的指标 LVSP、dp/dt max、V_(max)、V_(pm)、R-(dp/dt max 相继于中毒后4～6h 开始下降或延长,至6、7h 达到统计上的显著性。结果表明,T-2毒素急性中毒首先损害左室舒张性能,引起缺血损伤性变化,后期累及心肌收缩性,产生负性缩率和负性肌力效应。     

T－2毒素对肝脏脂质过氧化作用的体外效应

在体外观察了Ｔ－２毒素对大鼠及小鼠肝脏脂质过氧化的影响。结果表明，１－２毒素引起肝匀浆脂质过大化物丙二醛及脂褐素含量降低，并且这种变化存在时间和剂量效应关系；不同剂量Ｔ－２毒素对肝匀浆总巯基、蛋白巯基以及非蛋白巯基无明显影响。     

丁烯酸内酯对大鼠的脂质过氧化效应

目的：研究了丁烯酸内酯的脂质过氧化效应。方法：采用硫代巴比妥酸（ＴＢＡ）显色法及巯基含量测定等方法测定了脂质过氧化的代谢产物。     

T─2毒素和低硒饲料对雏鸡关节软骨基质代谢损伤的病理观察

用Ｔ－２毒素和低硒饲料喂养雏鸡，经组织化学方法观察软骨胶原和蛋白多糖含量的变化，结果发现，与对照组相比，低硒饲料组、Ｔ－２毒素组、Ｔ－２毒素加低硒组Ⅱ型胶原蛋白和硫酸软骨素、硫酸角质素含量均减少，Ⅰ型胶原含量增加，以Ｔ－２毒素加低硒组变化最为显著，低碱饲料组变化最小，而Ｔ－２毒素补硒组各项指标均接近正常。提示低硒和Ｔ－２毒素对软骨基质均有毒性作用，低硒能增强Ｔ－２毒素；硒；胶原蛋白；软骨素；硫酸角质素     

T2 quantitation of articular cartilage at 1.5 T

PURPOSE: To evaluate sources of error when using a multiecho sequence for quantitative T2 mapping of articular cartilage at 1.5 T. MATERIALS AND METHODS: Phantom measurements were used to assess the contribution of stimulated echoes to inaccuracy of T2 measurements in cartilage using a multiecho sequence. Five volunteer studies compared in vivo single-echo spin echo results to multiecho, single-slice and multiecho, multislice acquisitions for assessment of both the stimulated echo and magnetization transfer contrast (MTC) contributions to T2 measurement inaccuracy. RESULTS: Phantom experiments demonstrated that substantial inaccuracy (10%-13% longer T2 values) is introduced from stimulated echoes with a multiecho sequence with slice-selective refocusing pulses. The in vivo volunteer studies also demonstrated increases in measured T2 by up to 48% with a multiecho sequence. Use of the multiecho sequence in the multislice mode resulted in T2 values closer to the single-echo standards for the volunteer studies. However, this apparent increased accuracy should be regarded as circumstantial, as it only occurs because the error due to MTC has the opposite sign compared to the error due to the stimulated echo contribution. CONCLUSION: Use of a multiecho, multislice sequence for cartilage T2 measurements should be undertaken with the caution that substantial inaccuracy is introduced from stimulated echoes and MTC.     

正常人胫股关节软骨T2及T2*弛豫值的比较研究

目的:探讨正常志愿者膝关节软骨的T2及T2*弛豫值范围、影响因素及其内在相关程度。方法:将63名健康人胫股关节按照年龄分为青少年组(<35岁)18人、中年组(36~55岁)28人和老年组(56~78岁)17人,计算体重指数(BMI)并行T2图、T2*图成像,按照全器官磁共振成像评分(WORMS)规定的软骨分区法测量胫股关节软骨10个感兴趣区的T2、T2*弛豫率并取平均值,然后进行统计学分析。结果:健康人胫股关节软骨T2、T2*值分别为(42.98±4.19)ms、(19.75±2.43)ms。左右膝胫股关节T2、T2*值分别为(43.60±4.08 ms,42.37±4.26 ms)、(19.29±2.48 ms,20.21±2.37 ms),经检验两者均无明显统计学差异(P>0.05)。女性及男性胫股关节软骨T2、T2*值分别为(44.28±5.14 ms,41.86±4.09 ms)、(19.36±2.48 ms、20.09±2.42 ms),亦无明显统计学差异(P>0.05)。青少年组、中年组及老年组胫股关节软骨的T2、T2*值分别为(37.45±1.76 ms,41.29±2.13 ms,44.98±4.73 ms)、(17.95±1.58 ms,20.76±1.52 ms,22.30±2.08 ms),三组间有明显统计学差异(P<0.01)。青少年组、中年组及老年组三组内T2、T2*值均呈显著相关(P<0.05,Pearson相关系数分别为0.61、0.63、0.55)。结论:正常人胫股关节软骨T2及T2*弛豫值研究可以为关节软骨早期病变的诊断提供相似的参考价值,定量测定T2*值有望替代传统的T2值用于研究软骨形态学改变之前软骨内生化成分的变化。     

Radiofrequency pulses for simultaneous short T2 excitation and long T2 suppression

Magnetic resonance imaging of short T₂ musculoskeletal tissues such as ligaments, tendon, and cortical bone often requires specialized pulse sequences to detect sufficiently high levels of signal, as well as additional techniques to suppress unwanted long T₂ signals. We describe a specialized radiofrequency technique for imaging short T₂ tissues based on applying hard 180° radiofrequency excitation pulses to achieve simultaneous short T₂ tissue excitation and long T₂ tissue signal suppression for three‐dimensional ultrashort echo time applications. A criterion for the pulse duration of the 180° radiofrequency pulses is derived that allows simultaneous water and fat suppression. This opens up possibilities for direct imaging of short T₂ tissues, without the need for additional suppression techniques. Bloch simulations and experimental studies on short T₂ phantoms and specimen were used to test the sequence performance. Magn Reson Med, 2011. © 2010 Wiley‐Liss, Inc.     

Influence of knee positions on T2, T*2, and dGEMRIC mapping in porcine knee cartilage

We examined the influence of flexed knee positions on cartilage MR assessments. Sagittal T₂, T*₂, and delayed gadolinium‐enhanced MRI of cartilage (dGEMRIC) maps of the femoral cartilage were obtained in eight 6‐month‐old porcine femorotibial joints in the extended knee position (position A: flexion 0° and femoral shaft in parallel with the amplitude of static field), flexed knee position (position B: flexion 40° and femoral shaft oriented at 40° to the amplitude of static field), and oblique‐placed knee‐extended position (position C: flexion 0° and femoral shaft oriented at 40° to the amplitude of static field). Comparison of the MR parameters between positions A and C showed isolated influence of the magic‐angle effect, and comparison between positions A and B showed effects of knee flexion. Proteoglycan and hydroxyproline content in cartilage specimen at each region of interest had no significant correlation with T₂, T*₂, and dGEMRIC values. At the central zone, located on a weight‐bearing area and parallel to the amplitude of static field, T₂/T*₂/dGEMRIC values increased by 6.8/11/0.8% at position C and by 24/44/31% at position B compared with position A. There was a significant increase in T₂ and T*₂ values at position B compared with those at position A. The substantial changes in T₂, T*₂, and dGEMRIC were shown in response to knee flexion, presumably due to the compounding influence of the magic‐angle effect and change in the intra‐articular biomechanical condition. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.