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。     

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.     

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.     

黑蔓不同部位微量元素的测定

为了了解吉林省长白县山区所产卫矛科雷公藤属植物黑蔓的药理作用,扩大它的药用部位和应用范围,我们从无机元素与中药药效有密切关系的角度出发,实验测出黑蔓含有Ba、Si、Cu、Fe、Zn、Sn、Co、Mn、Mg、Ca、Se等无机元素,本文重点对其中人体必需的微量元素Cu、Fe、Zn、Se作了定量分析。     

WR-2721对γ线照射小鼠胃排空的防护作用

小鼠经γ线1200rad照射后胃排空受到明显抑制,如照前15min腹腔注射WR-2721 5mg或10mg对照后3天胃排空的抑制有明显改善。虽然WR-2721药物本身对胃排空具有一定的抑制作用,但经过24～48h后则可表现出对胃排空有一定程度的改善效应,这可能与该药减轻急性放射损伤的过程有关。     

小肝细胞癌的螺旋CT诊断

目的探讨小肝细胞癌的CT影像表现。方法回顾我院2001年2月-2005年2月经病理证实的12例小肝细胞癌的CT表现。结果通过平扫、动脉期、门脉期及部分延迟扫描均可对小肝细胞癌作出定性诊断。结论螺旋CT作为非创伤性容积扫描技术对小肝细胞癌的早期检出、定位、定性诊断具有十分重要的临床价值。     

新型记忆合金节段内固定器治疗腰椎峡部裂的实验研究

目的 :设计一种治疗腰椎峡部裂的新型记忆合金节段内固定器 ,测试其材料力学特性 ,并评价其生物力学稳定性。方法 :测量 2 0具干燥完整成人腰椎标本获得数据 ,按数据采用镍钛记忆合金设计固定器并行材料力学测试。取 6具新鲜成人腰椎标本 ,先后形成正常脊柱组、峡部裂组、横突棘突钢丝捆绑组、钩螺钉固定组、Buck螺钉固定组、新研制记忆合金固定器固定组 6组实验模型。利用脊柱三维运动实验机 ,分别测试 6组的前屈 /后伸、左 /右侧弯及左 /右轴向旋转 6种运动的活动范围。结果 :材料力学测试表明其形态记忆功能良好 ,体温状态下会产生稳定可靠的回复力。 6组在前屈、后伸及左右旋转状态 ,峡部裂组稳定性最差 ,同其他 5组差别明显。而使用新研制记忆合金内固定器组可明显恢复腰椎稳定性 ,同正常脊柱组及其他 3种内固定组均无显著差别。另两种状态左右侧弯 6组均无显著性差别。结论 :新设计的内固定器符合腰椎的生物力学要求 ,较先前的半环状内固定器优势明显 ,具有很好应用前景     

Effect of isoelectric point on biodistribution and inflammation imaging with indium-111-labelled IgG

Electrostatic effects play an important role in protein interactions and may alter the biodistribution of antibodies. To study the effect of molecular charge on the biodistribution and infection imaging properties of human polyclonal immunoglobulin G (IgG), its iso electric point was varied by changing the level of diethylene triamine penta-acetic acid (DTPA) substitution: 0.8, 0.9, 3.7, 5.1 and 5.9 DTPA/IgG. Biodistributions of the different IgG preparations were determined at 10 min, 1, 6, 24, and 48 h post injection in normal rats, and infection imaging properties were determined in rats withEscherichia coli thigh infections. The biodistribution was significantly affected by pl. The immunoglobulin preparations with 0.9 and 3.7 DTPA/IgG showed faster clearance from the circulation and generally lower accumulation in most organs. The images had a target-to-background ratio of approximately 1.3–2.3:1. These results suggest that even though targeting is not affected by the level of DTPA substitutions, preparations with 0.9 and 3.7 DTPA/IgG may be superior imaging agents because of reduced accumulation by background organs.     

京剧器乐的听力损伤（附55例调查报告）

本文对从事京剧打击乐的55人（110耳）进行了听力调查及动态观察。利用图表进行对比分析，发现110耳中高频听力损伤89耳，占81％；语频听力损伤32耳，占29.1%；其中伴有高频耳鸣78耳，占70．9％。动态观察30人（60耳），均为永久性听阈阈移。高频听力损伤最早出现的频率是4kHz，并见典型“V”谷，符合噪声性聋的诊断。