美国中东政策评析

美国在中东遇到大麻烦,主要战略目标未能实现。伊拉克安全形势持续严峻,巴以和谈停滞不前,伊朗核问题难以解决,压叙利亚屈服迄未奏效,恐怖活动越反越多,大中东改造计划受挫。美遇到的困难未超出其承受能力,美国在中东仍居主导地位,美中东政策在手法和策略上有所调整,实质上并无变化。     

γ-干扰素对大鼠胚胎基底前脑及隔区核团胆碱能神经元分化的影响

为了研究γ-干扰素(IFNγ)对大鼠胚胎基底前脑及隔区核团胆碱能神经元分化的作用,采用免疫组织化学方法对胆碱能神经元的特异性标记酶-胆碱乙酰基转移酶(ChAT)进行染色,ChAT阳性细胞的数量反映了胆碱能神经元的数量,并用14C-乙酰CoA作底物来检测ChAT活性。结果显示,IFNγ处理过的实验组,ChAT阳性细胞数量显著增加,ChAT活性也增加,这种增加被大鼠抗小鼠IFNγ单克隆抗体(Ab-IFNγ)完全拮抗。采用流式细胞术对细胞周期进行分析,细胞周期及细胞百分率无明显改变。用MAP2标记神经细胞,神经细胞数基本未增加。以上结果提示:IFNγ不能促进基底前脑和隔区神经元增殖,胆碱能神经元表达增加不是因为神经元数目增加而是分化的结果。     

国产rhGH的免疫原性及其对临床疗效的影响

目的　通过测定生长激素缺乏症 (GHD)患儿用国产重组人生长激素 (recom bined hum angrowth horm one,rh GH)治疗时血清生长激素抗体 (GH- Ab)水平及其结合特性 ,探讨 rh GH的免疫原性及其对疗效的影响。方法　对 6 1例 (男 49例 ,女 12例 ) GHD患儿用国产 rh GH治疗 ,每晚睡前皮下注射 rh GH 0 .1IU /kg共6个月 ;用放射免疫法测定治疗期间患儿血清 GH- Ab水平和滴度 ,并计算抗体结合容量、亲和常数 (Ka)。结果　48%患儿 (2 9/6 1)用药后 3个月血清 GH - Ab呈阳性至试验结束时仍未消失 ,其中 2 0例抗体为弱阳性 (结合率 <10 % ) ,9例呈强阳性 (结合率 >15 % ) ;5 2 %患儿 (32 /6 1)治疗期间抗体为阴性 ;血清 GH- Ab的结合容量、Ka及滴度均为低水平 ,分别为 (0 .1～ 4.8) pmol/L、(1.7× 10 7～ 6 .5× 10 8) L /mol和 1∶ 4～ 1∶ 8。GH- Ab阳性患儿治疗后的身高、身高增长速率及身高落后于正常 SD值的变化与同期阴性者比较无统计学差异 (P>0 .0 5 )。结论　本试验所用国产 rh GH对 GHD患儿身高增长具有确切的促进作用 ,其免疫原性所导致产生的 GH - Ab未对患儿体格线性增长产生负性影响     

Xenograft rejection--all that glitters is not Gal.

Xenotransplantation is being developed in the hope of resolvingthe critical shortage of donor organs for transplantation. TheEurotransplant waiting lists [1] for donor organs of variouskinds number almost 16 000 patients and the US lists [2] morethan 90 000 patients. Renal transplantation, for instance, cost-effectivelyconfers a significant survival advantage [3] and improvementof quality of life [4]. But whereas currently, in Europe, nearly12 000 end-stage renal disease patients await a suitable donor,only 3383 kidney transplants were performed in 2005, with anaverage waiting time of 1174 days [1]. Substantial researchefforts are being made in the field of xenotransplantation,and the immunological barriers are gradually being elucidated.Pig-to-human xenogeneic     

Screw angulation affects bone-screw stresses and bone graft load sharing in anterior cervical corpectomy fusion with a rigid screw-plate construct: a finite element model study

Background contextAnterior corpectomy and reconstruction with bone graft and a rigid screw-plate construct is an established procedure for treatment of cervical neural compression. Despite its reliability in relieving symptoms, there is a high rate of construct failure, especially in multilevel cases.PurposeThere has been no study evaluating the biomechanical effects of screw angulation on construct stability; this study investigates the C4–C7 construct stability and load-sharing properties among varying screw angulations in a rigid plate-screw construct.Study designA finite element model of a two-level cervical corpectomy with static anterior cervical plate.MethodsA three-dimensional finite element (FE) model of an intact C3–T1 segment was developed and validated. From this intact model, a fusion model (two-level [C5, C6] anterior corpectomy) was developed and validated. After corpectomy, allograft interbody fusion with a rigid anterior screw-plate construct was created from C4 to C7. Five additional FE models were developed from the fusion model corresponding to five different combinations of screw angulations within the vertebral bodies (C4, C7): (0°, 0°), (5°, 5°), (10°, 10°), (15°, 15°), and (15°, 0°). The fifth fusion model was termed as a hybrid fusion model.ResultsThe stability of a two-level corpectomy reconstruction is not dependent on the position of the screws. Despite the locked screw-plate interface, some degree of load sharing is transmitted to the graft. The load seen by the graft and the shear stress at the bone-screw junction is dependent on the angle of the screws with respect to the end plate. Higher stresses are seen at more divergent angles, particularly at the lower level of the construct.ConclusionThis study suggests that screw divergence from the end plates not only increases load transmission to the graft but also predisposes the screws to higher shear forces after corpectomy reconstruction. In particular, the inferior screw demonstrated larger stress than the upper-level screws. In the proposed hybrid fusion model, lower stresses on the bone graft, end plates, and bone-screw interface were recorded, inferring lower construct failure (end-plate fractures and screw pullout) potential at the inferior construct end.     

17 β雌二醇通过丝裂原活化蛋白激酶抑制前列腺癌细胞系PC3增殖

目的探讨丝裂原活化蛋白激酶在17β雌二醇(E2)抑制前列腺癌PC3细胞生长中的作用。方法检测不同浓度E2作用不同时间后PC3细胞生长抑制率。流式细胞仪分析细胞周期分布,TUNEL染色检测凋亡。Western blot检测ERK1/2,JNK和p38活性。RT-PCR法检测雌激素受体(ER)α、ERβ、P21WAF1和cyclinD1的表达。结果E2抑制PC3细胞增殖,并且可以激活ERK1/2、JNK和p38。处理因素作用48h后,对照组、E2、E2 PD98059、E2 SP600125、E2 SB203580组细胞的凋亡率分别为(0.9±0.1)%;(23.0±1.4)%;(30.0±1.2)%;(10.6±0.8)%和(14.6±0.7)%,(P<0.05)。E2使细胞阻滞在G1期,PD98059、SP600125、SB203580分别预处理1h后细胞分别进一步阻滞在G1期;轻度阻滞在G1期和进入S期。RT-PCR发现PC3细胞表达ERα和ERβ,E2、E2 PD98059、E2 SP600125、E2 SB203580组中cyclinD1、P21WAF1基因表达分别为对照组的(0.42±0.03)、(3.13±0.02)倍;(0.21±0.03)、(3.08±0.05)倍;(0.43±0.01)、(1.31±0.04)倍;(2.81±0.02)、(3.14±0.02)倍(P<0.05)。结论E2激活JNK增加P21WAF1基因表达,并激活p38抑制cyclinD1表达,使细胞阻滞在G1期,JNK和p38通路还介导E2引起PC3细胞凋亡。同时E2又可激活ERK1/2,轻度拮抗上述作用。     

Notochordal cells stimulate migration of cartilage end plate chondrocytes of the intervertebral disc in in vitro cell migration assays

Background contextIt was recently demonstrated that the postnatal transition from a notochordal to a fibrocartilaginous nucleus pulposus (NP) is accomplished exogenously by chondrocytes migrating from hyaline cartilage end plates (CEs) into the ectopic notochordal NP region. Although our previous in vivo studies showed evidences for the migration of CE chondrocyte from hyaline CEs into the notochordal NP, it is unknown whether CE chondrocytes of the intervertebral disc (IVD) really have a motile property. In addition, the effect of notochordal cells on this property has not been elucidated.PurposeThe purpose of this in vitro study was to demonstrate whether CE chondrocytes of the IVD are capable of migration, and whether there is any biological link between notochordal cells and CE chondrocytes that may regulate the CE chondrocyte migration.Study design/settingIn vitro cell migration assays were performed using rat IVDs.MethodsNotochordal cells and chondrocytes were obtained from the NP and CE tissues, respectively, and were cultured separately. The different numbers of notochordal cells and the supernatant (conditioned medium) that contained soluble factors produced by notochordal cells were used to demonstrate their effects on the migration of CE chondrocytes. Bovine serum albumin (BSA) and lysophosphatidic acid (LPA) were used as negative and positive controls, respectively.ResultsCompared with BSA, LPA, notochordal cells (N=4×, 2×, 1×, and 0.5×10⁵), and its conditioned media (unconcentrated and fivefold concentrated) significantly increased migration of CE chondrocytes (p<.05 in all comparisons). Particularly, notochordal cells and its conditioned media increased migration in a number- and concentration-dependent manner, respectively.ConclusionsThis study demonstrates that CE chondrocytes of the IVD are capable of migration and that soluble factors produced by notochordal cells stimulate the migration. These results provide a plausible explanation to the question of why CE chondrocytes of the IVD migrate into the ectopic NP region during the natural transition from the notochordal to fibrocartilaginous NP.