经肌间隙微创内固定术与传统椎弓根螺钉内固定术治疗胸腰椎骨折的疗效比较

目的：比较经肌间隙和传统切开椎弓根内固定治疗胸腰椎骨折的临床疗效和安全性。方法：选取我院2010 年1 月-2014 年 12 月收治的胸腰椎骨折患者120例,分为微创手术组和开放手术组。观察并对比两组患者的手术时间、术中出血量、住院时间及 术后恢复情况。结果：两组患者的手术时间比较差异无统计学意义（P>0.05）。与开放手术组比较,微创组患者术中出血量显著减 少、住院时间明显缩短,差异具有统计学意义（P<0.05）。与手术前比较,两组患者术后Cobb 角及伤椎高度均明显改善,差异具有 统计学意义（P<0.05）,但两组间比较差异无统计学意义（P>0.05）;两组患者术后JOA 评分均显著降低,差异具有统计学意义（P<0. 05）,但两组间比较差异无统计学意义（P>0.05）。结论：经肌间隙微创内固定术与传统椎弓根螺钉内固定术均能较好的复位固定胸 腰椎骨折,但经肌间隙微创内固定术具有创伤小、术中出血少、功能恢复快、住院周期短等优势,值得临床推广应用。     

Crystal Structure and Catalytic Mechanism of Leucoanthocyanidin Reductase from Vitis vinifera

Leucoanthocyanidin reductase (LAR) catalyzes the NADPH-dependent reduction of 2R,3S,4S-flavan-3,4-diols into 2R,3S-flavan-3-ols, a subfamily of flavonoids that is important for plant survival and for human nutrition. LAR1 from Vitis vinifera has been co-crystallized with or without NADPH and one of its natural products, (+)-catechin. Crystals diffract to a resolution between 1.75 and 2.72 Å. The coenzyme and substrate binding pocket is preformed in the apoprotein and not markedly altered upon NADPH binding. The structure of the abortive ternary complex, determined at a resolution of 2.28 Å, indicates the ordering of a short 3₁₀ helix associated with substrate binding and suggests that His122 and Lys140 act as acid-base catalysts. Based on our 3D structures, a two-step catalytic mechanism is proposed, in which a concerted dehydration precedes an NADPH-mediated hydride transfer at C4. The dehydration step involves a Lys-catalyzed deprotonation of the phenolic OH7 through a bridging water molecule and a His-catalyzed protonation of the benzylic hydroxyl at C4. The resulting quinone methide serves as an electrophilic target for hydride transfer at C4. LAR belongs to the short-chain dehydrogenase/reductase superfamily and to the PIP (pinoresinol-lariciresinol reductase, isoflavone reductase, and phenylcoumaran benzylic ether reductase) family. Our data support the concept that all PIP enzymes reduce a quinone methide intermediate and that the major role of the only residue that has been conserved from the short-chain dehydrogenase/reductase catalytic triad (Ser…TyrXXXLys), that is, lysine, is to promote the formation of this intermediate by catalyzing the deprotonation of a phenolic hydroxyl. For some PIP enzymes, this lysine-catalyzed proton abstraction may be sufficient to trigger the extrusion of the leaving group, whereas in LAR, the extrusion of a hydroxide group requires a more sophisticated mechanism of concerted acid-base catalysis that involves histidine and takes advantage of the OH4, OH5, and OH7 substituents of leucoanthocyanidins.     

The Critical Roles of Residues P235 and F236 of Subunit A of the Motor Protein A-ATP Synthase in P-Loop Formation and Nucleotide Binding

The mutants P235A and F236A have been generated and their crystal structure was determined to resolutions of 2.38  and 2.35 Å, respectively, in order to understand the residues involved in the formation of the novel arched P-loop of subunit A of the A-ATP synthase from Pyrococcus horikoshii OT3. Both the structures show unique, altered conformations for the P-loop. Comparison with the previously solved wild type and P-loop mutant S238A structures of subunit A showed that the P-loop conformation for these two novel mutants occupy intermediate positions, with the wild type fully arched and the well-relaxed S238A mutant structures taking the extreme positions. Even though the deviation is similar for both mutants, the curvature of the P-loop faces the opposite direction. Deviations in the GER-loop, lying above the P-loop, are similar for both mutants, but in F236A, it moves towards the P-loop by around 2 Å. The curvature of the loop region V392-V410, located directly behind the P-loop, moves close by 3.6 Å towards the P-loop in the F236A structure and away by 2.5 Å in the P235A structure. Two major deviations were observed in the P235A mutant, which are not identified in any of the subunit A structures analyzed so far, one being a wide movement of the N-terminal loop region (R90-P110) making a rotation of 80° and the other being rigid-body rotation of the C-terminal helices from Q520-A588 by around 4° upwards. Taken together, the data presented demonstrate the concerted effects of the critical residues P235A, F236, and S238 in the unique P-loop conformation of the A-ATP synthases.     

生物柱锥式螺旋模型

自从阿基米德(Archimedes)第一部关于螺旋结构的著作问世以来,螺旋现象引起了人们的重视和研究。植物的叶、叶柄、茎等变态形成的藤、蔓或卷须往往是以螺旋形式攀缘缠绕;动物体表有毛的兽类,在头额顶上或背上都有1、2个毛螺,毛呈螺旋排列。本世纪30年代,阿基特伯利(Astbury)首次用x射线研究蛋白质结构,发现角蛋白类中多肽链有不同方式的盘旋或卷曲,第一次发现生物大分子的螺旋结构;     

Interaction of heparin with antithrombin III and platelet factor 4: pH dependence demonstrated with a new rocket precipitin electrophoretic procedure

Only 30% of commercial heparin reacts with antithrombin III (ATIII). This study shows that the interaction is pH dependent: 100% of the heparin binds to ATIII at pH 3.0, 30% at physiological pH. Binding of ATIII, platelet factor 4, and protamine to heparin was studied using a new rocket precipitin electrophoresis procedure, adapted from the Laurell rocket immunoelectrophoresis procedure. Protamine is incorporated into agarose gel, and heparin mixtures with protamine, ATIII, or platelet factor 4 electrophoresed into the gel from a series of wells. The residual free heparin is precipitated by the protamine in a rocket-shaped arc, the height of which is proportional to the amount of free heparin. No antibody is employed. This procedure is useful for quantitation of heparin and for studying the binding of heparin to proteins.     

BOLD钉治疗桡骨小头骨折的临床疗效分析

目的:报告BOLD钉治疗Mason II型、未累及桡骨颈的Mason III型桡骨小头骨折的临床疗效。方法:自2009年3月至2012年2月对25例Mason II型,12例Mason III型桡骨小头骨折均采用切开复位BOLD钉内固定。结果:所有患者术后均获得随访12-24个月,平均随访14个月,肘关节功能评分:Mason II型平均分94分(88-98分),其中,优20例,良3例,可2例,差0例,优良率92%;Mason III型平均分91分(80-95分)其中,优9例,良1例,可2例,差0例,优良率83.3%。结论:BOLD钉治疗Mason II型及未累及桡骨颈的Mason III型桡骨小头有手术操作简单,固定稳定,允许早期活动等优点,可以作为这类骨折治疗的新选择。     

不同后路术式治疗胸腰椎爆裂骨折的临床效果比较

目的：探讨不同后路术式治疗胸腰椎爆裂骨折的临床效果。方法：将我院骨科收治的96例胸腰椎爆裂骨折患者随机分为两组,分别使用经伤椎椎弓根六钉固定法（六钉组,65例）和跨伤椎短节段四钉固定法（四钉组,31例）进行复位固定,测量并比较术后6个月两组矢状面Cobb角、冠状面Cobb角和伤椎椎体前缘压缩比及术后并发症情况的差异。结果：两组患者术前矢状面和冠状面Cobb角、伤椎椎体前缘压缩比的差异无统计学意义（P〉0．05）。术后6个月,六钉组矢状面Cobb角、伤椎椎体前缘压缩比、术后并发症发生率均显著低于四钉组（P〈0．05）,两组冠状面Cobb角均为0°。四钉组术后并发痘的发生率为22．6％,而六钉组术后并发症的发生率为4．6％,显著低于四钉组（P〈0．05）。结论：经伤椎椎弓根六钉固定法治疗胸腰椎爆裂骨折疗效优于跨伤椎短节段四钉固定法．且不良反应较少．具有较高的临床应用价值。     

Reasons why dynamic compression plates are inferior to locking plates in osteoporotic bone: a finite element explanation

While locking plate fixation is becoming increasingly popular for complex and osteoporotic fractures, for many indications compression plating remains the standard choice. This study compares the mechanical behaviour of the more recent locking compression plate (LCP) device, with the traditional dynamic compression plates (DCPs) in bone of varying quality using finite element modelling. The bone properties considered include orthotropy, inhomogeneity, cortical thinning and periosteal apposition associated with osteoporosis. The effect of preloads induced by compression plating was included in the models. Two different fracture scenarios were modelled: one with complete reduction and one with a fracture gap. The results show that the preload arising in DCPs results in large principal strains in the bone all around the perimeter of the screw hole, whereas for LCPs large principal strains occur primarily on the side of the screw proximal to the load. The strains within the bone produced by the two screw types are similar in healthy bone with a reduced fracture gap; however, the DCP produces much larger strains in osteoporotic bone. In the presence of a fracture gap, the DCP results in a considerably larger region with high tensile strains and a slightly smaller region with high compressive strains. These findings provide a biomechanical basis for the reported improved performance of locking plates in poorer bone quality.     

Bold螺钉治疗内踝骨折的疗效分析

目的：对比Bold螺钉和普通空心螺钉内固定治疗单纯内踝骨折的疗效。方法：空心螺钉治疗单纯内踝撕脱骨折57例,分为A组Bold螺钉内固定治疗内踝骨折25例,B组使用普通空心螺钉内固定32例。结果：两组57例均获得随访,两组病例远期均能得到较坚强的固定和良好的功能恢复,但Bold螺钉组相对普通螺钉组愈合时间更快（P〈0.05）,下床活动时间更早（P〈0.05）,早期踝关节功能评分高（P〈0.05）,但六个月后没有明显差异。结论：Bold螺钉内固定有助于内踝骨折早期愈合和早期功能锻炼,是一种比较好的内固定材料,值得推广。     

生物活性玻璃提高骨质疏松绵羊椎弓根螺钉稳定性的体内实验研究

目的:研究生物活性玻璃(Bioactive Glass,BG)在骨质疏松绵羊体内强化椎弓根螺钉固定的力学效果,并观察钉道界面及材料吸收等情况。方法:4只成年雌性小尾寒羊,采用去势联合激素注射方法建立骨质疏松绵羊模型。选择绵羊L2至L5双侧椎弓根,随机化选取一侧直接拧入椎弓根螺钉(空白组),对侧采用BG强化钉道后拧入椎弓根螺钉(实验组)。术后3月随机选取6个椎体(12枚椎弓根螺钉),对螺钉骨质界面行显微CT分析和组织学观察。对剩余10个椎体(20枚椎弓根螺钉)行轴向拔出实验,分析螺钉固定强度。结果:术前绵羊腰椎BMD为0.818±0.0310 g/cm2,建模完成后为1.000±0.0316 g/cm2,BMD平均值下降22.38%,差异有统计学意义(P<0.05)。实验组螺钉骨质界面的Tb.Th、Tb.N组较对照组分别增加143.60%和33.56%,差异有统计学意义(P<0.05)。实验组钉道周围材料绝大部分已经降解吸收,大量新生骨组织紧密包裹螺钉;对照组钉道周围骨量较少,钉骨结合不紧密,实验组螺钉骨质界面结合优于对照组。实验组的最大轴向拔出力为1083.04±86.37N,空白组为871.76±79.03N,前者较后者提高25.26%,差异有统计学意义(P<0.05)。结论:生物活性玻璃能显著改善骨质疏松情况下螺钉骨质界面的骨微观结构,进而提高椎弓根螺钉的把持力。