Average and peak contact stress distribution evaluation of total knee arthroplasties

Seven total knee arthroplasty systems were tested to determine contact stress patterns and contact areas using a calibrated Fuji film stress analysis technique. Knees were loaded to 2,000 N (204 kg) at 15°, 60°, 90°, and 135° flexion at 24 and 37°C. Evaluation of stresses at 37°C at 15° and 60° using an average contact stress assessment technique indicated that the LCS meniscal bearing knee system, (DePuy, Warsaw, IN), the AMK knee with a constrained insert (DePuy), and the PFC knee with a posterior-lipped insert (Johnson and Johnson, Raynham, MA) had the lowest average contact stresses (near or below 10 MPa). The PFC with a regular insert (Johnson and Johnson), the Ortholoc II (Dow Corning Wright, Arlington, TN), and the AMK with a regular insert (DePuy) had intermediate contact stresses. The AMK with a Hylamer-M insert (DePuy) and the MG II (Zimmer, Warsaw, IN) had the highest average contact stresses (near or above 20 MPa). A stress-calibrated Fuji film measurement technique has shown that an assessment of ranges of contact stress provides much more information about regions of expected wear than an assessment of average contact stresses. Testing of the tibiofemoral articulation of artificial knees revealed that all knees had some areas of contact with maximum stresses in excess of 15 MPa. As the yield strength of ultrahigh-molecular-weight polyethylene is approximately 15 MPa, all tibial inserts could wear to some extent. Peak contact stresses at four test angles of the AMK, Series 7000 (Osteonics, Allendale, NJ:) Genesis (Smith & Nephew Orthopaedics, Memphis, TN), and MG II patellofemoral articulations were high (above 30 MPa). Contact areas varied from line-shaped to bilateral circular or elliptical shapes. The LCS knee system experienced substantially lower patellofemoral contact stresses and larger contact areas. Changes in conformity of knee designs are warranted to overcome wear problems. Peak contact stresses measured from the LCS meniscal bearing tibiofemoral and patellofemoral joint were in excess of 30 MPa in some areas at low flexion angles. This design does create large areas of contact at very low contact pressures, however, and for this reason is expected to wear less than other designs.     

先天性输精管缺如患者生育问题的研究

自1988年至1991年共收治25例先天性输精管缺如患者,在20例行手术诊治术中15例用自体睾丸精索鞘膜制成人工精池囊,5例又在囊内放置用微涤纶制成的异质管。术中抽吸10例附睾内精子进行快速活化,其中5例活化成功,行人工授精,结果2例怀孕,1例已生育一女孩。认为该症是有生育可能的,但需要解决3个问题:(1)采用显微外科技术把附睾内部活着的精子取出一定数量;(2)选配好快速活化剂使精子快速活化成功;(3)用患者的精浆培养自己的精子。建议对梗阻性无精子症在用手术疏通精路的同时可以采用快速活化精子技术行人工授精,以提高生育的效果。     

Cyclic analogues of Thr6-bradykinin,N8-Lys-bradykinin and endo-Lys8a-vespulakinin 1

Syntheses are described of the endo-Lys^8a-vespulakinin 1 and of cyclo-Thr⁶- and cyclo-N^ε-Lys-bradykinin. The linear peptides covering the entire sequences of endo-Lys^8a-VSK-1 and Thr⁶-BK, and the decapeptide containing all residues constituting Lys-BK, with a Arg-Lys peptide bond involving the ε-amino function of lysine, were prepared by the solid-phase procedure based on Fmoc chemistry. Cyclization was carried out by the diphenylphosphorazide method. The amino-terminal octapeptide sequence of vespulakinin 1, Fmoc-Thr(tBu)-Ala-Thr(tBu)-Thr(tBu)-Arg(Pmc)-Arg(Pmc)-Arg(Pmc)-Gly-OH, and its N^α-Boc-[(Gal β)Thr³, (Gal β)Thr⁴]-analogue, were used to prepare N^α-(1–8 VSK 1)-cyclo-N^ε-kallidin and N^α-[(Gal β)Thr³, (Gal β)Thr⁴, 1–8 VSK 1]-cyclo-N^ε-kallidin. Peptides and glycopeptides were characterized by amino-acid analysis, optical rotation, analytical HPLC and FAB-MS. Consistent with previous findings, preliminary pharmacological experiments on smooth muscle preparations showed that the cyclic, or partially cyclic, analogues were significatively less potent than the linear ones. © Munksgaard 1995.     

54例严重缓慢心律失常病人的起搏器治疗

1978年～1987年用永久起搏器治疗54例严重缓慢心律失常的病人,共进行103次手术。随访8年多,发现7例死亡,其中6例死亡原因与起搏器治疗无关,1例死于与起搏器并发感染密切相关。本文就严重缓慢心律失常的类型、病因、安装永久起搏器的指征、手术并发症等加以讨论。     

Antibody reactivity to a synthetic peptide (P62) of the Epstein-Barr nuclear antigen in sera of patients with X-linked lymphoproliferative syndrome

An enzyme-linked immunosorbent assay (ELISA) was used to measured IgG antiboody titers againt a synthetic peptide whose sequence was derived from the glycine-alanine repeating region of Epstein-Barr virus nuclear associated antigen 1 (EBNA-1). Antibody titers were determined in sera from 15 normal subjects, sera from 21 normal male siblings of X-linked lymphoproliferative syndrome (XLP) patients, from 20 XLP patients comprising a total of 42 samples, and ten samples before and ten samples after gamma-globulin therapy in ten patients with XLP. Data analysis demonstrated that while there are differences between the ELISA and ACIF, they appear to measure a similar response as demonstrated by their correlation coefficient (0.77) and the GMT to EBNA observed by both methods. No cross-reactivity of cytomegalovirus antibodies to the EBNA-1 peptide was observed by immunobv using adsorption against AD-169 infected MRC-5 cells.. However, non-specific binding was observed if samples were not pre-incubated in a 10% goat serum PBS-Tween 20 solution. This pre-treatment removed the non-specific binding that falsely elevated GMT in approximately 15% of both normal and XLP samples in ELISA. The ELISA system appears to be a sensitive, reproducible and objective test that may be useful for assessing the antibody responses of patients to the EBNA-1 protein.     

不同微生物诱导家蝇幼虫表达抗菌肽的特性

研究不同微生物诱导家蝇幼虫表达的抗菌肽特性.用3种不同的病源菌通过针刺感染的方法诱导家蝇幼虫表达抗菌肽,通过Sephadex G25分离,用Hult mark改进法和抑菌圈测定法作抑菌试验,用毛细管电泳（CE）分析不同微生物诱导得到的抗菌肽样品差异,检测抗菌肽的热稳定性和酸碱耐受性.发现不同微生物诱导产生的家蝇抗菌肽具有广谱抑菌性,但不同样品对不同病源菌抑菌活性有差异,不同测定抑菌效果的方法对抑菌结果有影响,各种抗菌肽样品CE蛋白谱具有明显不同.抗菌肽样品都具有热稳定性和酸碱耐受性.说明不同微生物诱导产生的家蝇抗菌肽类型以及抗菌肽含量与诱导源有关,抗菌肽为家蝇幼虫体内固有成分,诱导增加了抗菌肽的表达量同时刺激新抗菌肽的产生.用志贺氏菌、金黄色葡萄球菌、鼠伤寒沙门氏菌诱导家蝇幼虫可产生较多含量高活性好的抗菌肽.     

血管内皮细胞和成纤维细胞混合移植对人工真皮血管化的影响

目的观察同种血管内皮细胞和成纤维细胞移植对人工真皮血管化的促进作用。方法在27只Wistar大鼠背部造成2．5 cm×2．5 cm全层皮肤缺损创面(2处／只),将其分为血管内皮细胞组:将血管内皮细胞混入0．5 ml纤维蛋白胶中,按1．0×105／cm2的密度均匀喷洒于移植床;混合组:将血管内皮细胞和成纤维细胞混入等量纤维蛋白胶后,同前密度喷洒于移植床;对照组:按同样方法喷洒等量纤维蛋白胶。随后各组移植人工真皮,每组9只大鼠18处创面。于移植后5、10 d切取移植的真皮及周围组织行HE、血管内皮生长因子(VEGF)、Masson和墨汁灌注染色,观察新生血管生长情况。于移植后5 d行伊文思蓝灌注,以分光光度计定量检测法测定微血管形成情况。结果移植后5 d,HE、VEGF、Masson和墨汁灌注染色均可见各组移植床有新生血管长入。HE染色见血管内皮细胞组、混合组新生血管数量分别为(14．2±3．6)、(12．1±2．5)条,较对照组[(3．9±1．6)条]明显增多(P<0．05)。移植后10 d,人工真皮内及移植床均有微血管形成,且胶原组织的合成增加。移植后5 d,经伊文思蓝灌注,收集并检测血管内皮细胞组、混合组真皮组织溶出的上清液,吸光度值分别为0．167±0．058、0．155±0．046,均高于对照组的0．066±0．024(P<0．05)。结论同种血管内皮细胞和成纤维细胞移植可促进创面愈合过程中的血管新生,加速人工真皮移植后血管化过程,促进类真皮组织的成熟。     

贺斯预防骨水泥所致低血压的临床探讨

目的:观察6%贺斯预防骨水泥所致低血压的效果。方法:30例人工股骨头置换病人随机分为两组:Ⅰ组为6%贺斯组(n=15);Ⅱ组为平衡盐组(n=15)。在填充骨水泥前分别输入6%贺斯及平衡盐500ml,分别测定入室(基础)、填充骨水泥前1min收缩压、填充骨水泥后5min最低收缩压,并观察心率变化。结果:Ⅰ组用骨水泥后最低收缩压明显高于Ⅱ组(P<0.01)。I组低血压发生率仅为13.3%,而Ⅱ组为60%。结论:在填充骨水泥前输注胶体能有效预防骨水泥所致的低血压。     

人工股骨头置换治疗高龄股骨颈骨折

1996年12月~2002年6月,我院应用人工股骨头置换术治疗80岁以上股骨颈骨折患者21例,效果满意。1材料与方法1.1病例资料本组21例,男4例,女17例,年龄80~89岁。其中2例脑血管疾病后轻度偏瘫。健侧发生股骨颈骨折。材料选用常州市康辉医疗器械有限公司产双极人工股骨头。1.2治疗方法