Precise and accurate measurement of proton T1 in human brain in vivo: Validation and preliminary clinical application

Precise and accurate inversion-recovery (PAIR) magnetic resonance (MR) measurements of T1 were obtained in eight brain regions and cerebrospinal fluid of 26 healthy volunteers. Accuracy of the technique was assessed by measuring T1 in small fluid volumes with the PAIR technique and with two independent spectroscopic techniques. The mean difference between T1 measured with PAIR and with the two spectroscopic techniques was 3.1% ± 1.3. The precision (reproducibility) of measurements with the PAIR technique was excellent. The coefficient of variation (CV) across 16 measurements in a head phantom was 2.0%, compared with a CV of 2.7% across 45 separate measurements in a single subject. The within-subject CV was 1.8% ± 0.6 in white matter and 1.4% ± 1.0 in basal ganglia. The between-subject CV in 26 healthy volunteers was 3.6% ± 0.6 in white matter and 4.1% ± 1.9 in basal ganglia. Comparison between a patient with an active recurrent brain tumor and an agematched patient with an inactive brain tumor showed that T1 was significantly elevated throughout the brain of the active-tumor patient, especially in white matter tracts, even though no tumor or edema was detected in the white matter on standard MR images. Comparisons between five brain tumor patients and four healthy volunteers of similar age showed that T1 was significantly and substantially elevated throughout the white matter tracts and in the caudate nucleus, putamen, and thalamus. These results are consistent with the hypothesis that white matter tracts are selectively vulnerable to edema and that T1 increases in white matter are a sensitive indicator of patient status or tumor aggressiveness.     

组织型纤溶酶原激活物双单抗夹心ELISA建立及临床应用

本文动用自制ｔ－ＰＡ单克隆抗体建立ｔ－ＰＡ：Ａａ夹心ＥＬＩＳＡ法。结合ｔ－ＰＡ：Ａ、ＰＡＩ：Ａ测定，对５０例正常人，８７例肝病，４７例冠心病和１９例深静脉血栓 成患者的血浆ｔ－ＰＡ：Ａｇ、ｔ－ＰＡ：Ａ、ＰＡＩ：Ａ水平进行了研究。     

生物衍生骨复合骨髓基质干细胞修复山羊胫骨缺损的血管化研究

目的研究生物衍生骨与骨髓基质干细胞(marrow stromal stem cells, MSCs)复合修复山羊胫骨缺损的血管化过程,了解其修复长段管状负重骨缺损的血管化情况. 方法制备生物衍生骨作为支架材料,培养、诱导MSCs作为种子细胞,二者在体外复合构建组织工程骨.20只山羊双侧胫骨中段制备成20 mm长的骨-骨膜缺损模型,采取自身左右侧对照,实验侧(右侧)缺损处植入组织工程骨,对照侧(左侧)植入单纯支架材料,采用钢板内固定.术后2、4、6及8周用墨汁灌注透明标本及血管面积图像分析方法观察血管化过程,组织学观察血管形成及成骨情况. 结果术后2、4周,实验侧血管形成较对照侧少(P<0.05);术后8周,两侧均完全血管化,差异无统计学意义(P>0.05).实验侧于术后6、8周新骨形成逐渐增加,材料降解吸收较对照组快;对照侧术后8周材料孔隙内仍无明显新骨形成. 结论生物衍生骨作为骨组织工程的支架材料,能够较快发生血管化;组织工程骨成骨能力较单纯支架材料强.     

Time after excision and temperature alter ex vivo tissue relaxation time measurements

Previously unreported effects of tissue storage were recently observed in the authors' experimental magnetic resonance (MR) studies. To evaluate the effect of elapsed time after excision and storage temperature on tissue relaxation time measurements, tissue samples from the liver, pancreas, kidney, testis, spleen, and brain were obtained in rats. T1 and T2 were first measured within 5 minutes of excision, and between subsequent measurements, tubes were kept in a water bath at 40°C, at room temperature (28°C), or in an ice bath (4°C). Cellular and organellar integrity was assessed with electron microscopy and correlated with the MR findings. At 40°C (20-MHz spectrometer), the T1 of liver decreased from 280 msec ± 8 to 212 msec ± 10 during the first 60 minutes; the T1 of pancreas decreased from 276 msec ± 3 to 208 msec ± 2. Other tissues showed less than a 5% decrease in T1. T2 changes were smaller than T1 changes in all tissues. Electron microscopy of pancreatic acinar cells showed postmortem changes in mitochondria evolving over the first 60 minutes after death. Manganese loading experiments implicated mitochondrial manganese stores in the observed enhanced postmortem decrease in T1. This study calls into question reported relaxation time data for liver and pancreas. MR studies of excised tissues must account for time and temperature to prevent systematic experimental errors.     

乳腺肿瘤组织中Ⅰ型纤溶酶原激活物抑制剂的表达

探查乳腺肿瘤组织中Ⅰ型纤溶酶原激活物抑制剂（ＰＡＩ－１）的表达，并比较乳腺恶性肿瘤组织与良性纤继腺瘤及正常组织中ＰＡＩ－１的差异。用免疫组织化学和原位杂交的方法，确定了乳腺癌、乳腺纤维腺瘤及瘤旁正常组织中ＰＡＩ－１的分布；用发色底物法检测组织提取液中ＰＡＩ－１的活性；用图象分析的方法对组织切片上的ＰＡＩ－１进行灰度定量。结果：ＰＡＩ－１主要分布在乳腺正常腺上皮细胞、瘤上皮细胞和腺癌细胞的胞浆中，但恶性组织中的成纤维细胞、巨噬细胞以及癌旁纤维组织也有染色。癌组织中ＰＡＩ－１的活性（Ｐ＜０．００１）和含量（Ｐ＜０．００５）均高于良性乳腺纤维腺瘤及瘤旁正常组织。结论：ＰＡＩ－１在乳腺恶性肿瘤组织中明显升高，ＰＡＩ－１的检测可能为临床乳腺肿瘤的诊断、预后提供新的指标。     

藻酸钙凝胶-成骨细胞-骨粉构建工程化骨修复兔颅骨缺损的实验研究

目的探讨藻酸钙凝胶、成骨细胞、骨粉复合构建的可塑形组织工程骨修补兔颅骨缺损后的形态学变化和成骨效果.方法28只日本大耳白兔,随机分为A(n=20)、B(n=8)两组,手术在兔颅顶骨矢状缝两侧分别各建立一个直径1cm的圆形全层缺损,用两种方法藻酸钙凝胶、成骨细胞、骨粉和藻酸钙凝胶、骨粉分别构建组成可塑形的组织工程骨复合材料,分别填补修复A组兔颅骨左右两侧的缺损,B组为空白对照组,通过大体、组织学、X线观察材料的形态变化、成骨情况,并对X线片和组织学切片进行评分.结果材料植入后,局部未见红肿、积液、渗出等异常反应.①藻酸钙凝胶-成骨细胞-骨粉组修补后12周颅骨缺损基本被硬性组织所修复,镜下见修复材料大多被骨组织替代,骨粉基本被吸收,有块状凝胶残留其中,组织学评分为(5.50±1.00).X线片见兔颅骨缺损处有高密度骨痂影存在,布满整个缺损区,X线片评分为(3.25±0.95).②藻酸钙凝胶-骨粉组修补后12周部分颅骨缺损被硬性组织所修复,镜下见修复材料部分转变成骨组织,骨粉基本被吸收,有凝胶残留其中,组织学评分为(3.25±1.50).X线片见兔颅骨缺损处有高密度骨痂影存在,主要分布在缺损区的边缘部位,X线片评分(2.25±0.25).③空白对照组骨缺损主要被膜样纤维组织修复,在紧邻骨缺损边缘处有硬性组织形成,镜下见修复组织边缘有骨组织存在,中央大部为膜状致密纤维组织,组织学评分为(1.50±0.50),X线片仅见靠近骨缺损边缘的部位存在致密骨痂影,X线片评分为(1.00±0.57).结论藻酸钙凝胶、成骨细胞、骨粉构建的可塑形组织工程骨可根据颅骨缺损的形态进行塑形填补,在体内有良好的成骨能力,可达到对兔颅骨缺损的骨性修复,但部分藻酸盐凝胶吸收缓慢,手术后12周仍不能满意吸收.     

骺板软骨细胞复合三维支架体外构建组织工程软骨的研究

目的探讨将骺板软骨细胞复合三维支架经体外培养,构建组织工程软骨的效果及其生物学特点. 方法将3周龄幼兔第1代骺板软骨细胞与液态的生物凝胶混合,接种于聚磷酸钙纤维/L-聚乳酸(CPPF/PLLA)三维支架材料,构建组织工程软骨组织块,连续培养4周.行大体、倒置显微镜及组织学、Ⅰ型和Ⅱ型胶原免疫组织化学光镜观察,定量检测硫酸糖胺多糖(GAG)含量. 结果构建的组织工程软骨块在培养过程中能保持其初始外形,种子细胞呈稳定的三维均相分布,外观逐渐呈乳白色、半透明,硬度亦不断增加.培养1周有软骨细胞陷窝形成,2周后形成富含Ⅱ型胶原和蛋白聚糖、具有典型软骨组织结构的工程化软骨,且Ⅰ型胶原逐渐转为阴性.4周时构建软骨的组织结构与天然骺板软骨相类似,硫酸GAG含量平均为天然骺板软骨的34%以上. 结论骺板软骨细胞复合三维支架体外培养可生成典型软骨,且可形成类似天然骺板软骨的组织结构,能满足修复骺板缺损的基本要求.体外培养1～2周可能是植入体内修复骺板缺损的较佳时机.     

rhBMP-2对不同培养时间骨髓基质干细胞成骨能力的影响

目的：探讨不同培养阶段骨髓基质干细胞成骨能力的变化及BMP-2对其成骨能力的影响。方法：培养兔骨髓基质干细胞，测定第3代和第18代细胞碱性磷酸酶及骨钙素活性；测定BMP-2对不同培养时间骨髓基质干细胞成骨能力的影响；测定rhBMP-2对细胞增殖的影响。结果：细胞传至第18代后，分泌的骨钙素（OC）水平及ALP活力明显降低，与第3代细胞相比，差异显著（P〈0．05）。第3代细胞在rhBMP-2的诱导下，分泌的OC水平及ALP活力在原基础上进一步升高，与对照组相比，差异显著（P〈0.05）。结第18代细胞在rhBMP-2的诱导下，分泌的OC水平及ALP活力在原基础上升高，与对照组相比，差异不显著（P〉0．05）；随培养时间的延长，各组细胞数量均有所增加，rhBMP-2诱导组与对照组细胞无显著性差异（P〉0．05）。细胞的传代次数对细胞增殖无明显影响（P〉0．05）。结论：rhBMP-2对细胞增殖无影响。随着传代次数的增加，骨髓基质干细胞的成骨能力下降，rhBMP-2促进其成骨的能力亦下降。     

糖基化终末产物对大鼠肾系膜细胞纤溶酶原激活物抑制物-1表达韵影响

目的：观察糖基化终末产物（AGEs）对大鼠肾系膜细胞纤溶酶原激活物抑制物-1（PAI-1）表达的影响及其与细胞外基质（ECM）成分含量的关系。方法：体外培养正常大鼠肾系膜细胞，分别用糖化牛血清白蛋白（AGEs）及未经糖化的牛血清白蛋白（BSA）处理，以常规培养的肾系膜细胞作为对照，检测不同时间、不同浓度AGEs对纤维连接蛋白（FN）、Ⅳ型胶原、PAI-1表达的影响。MTT法检测AGEs对系膜细胞增殖的作用，ELISA测定条件培养基中FN、Ⅳ型胶原及PAI-1蛋白含量，逆转录聚合酶链式反应（RT—PCR）检测系膜细胞PAI-1 mRNA的表达。结果：与相应浓度的BSA比较，AGEs（0—200mg／L）对系膜细胞增殖无明显影响，但可不同程度地刺激系膜细胞FN、Ⅳ型胶原、PAI-1蛋白的产生。RT—PCR检测显示，给予AGEs（100mg／L）的系膜细胞PAI-1 mRNA的表达明显增加（P〈0．01）。结论：AGEs促进系膜细胞PAI—1的表达，提示AGEs通过上调PAI-1的表达而减少细胞外基质降解，可能是糖尿病肾病细胞外基质积聚的原因之一。