一种新型腰椎可降解椎间融合器的体外生物力学评价

目的介绍一种新型腰椎可降解椎间融合器(cage)的设计理念和结构,对其生物力学性能进行初步评价。方法采用新型可降解骨水泥-磷酸镁水泥(Magnesium phosphate cement,MPC)经过特殊模具压缩凝固成可降解椎间融合器作为实验组(n=8),大小型号相同聚醚醚酮(PEEK)椎间融合器(n=8)及取猪髂骨块做成的三面皮质骨椎间融合器(n=8)作为对照组,利用Instron 10000N生物力学机做压缩载荷测试。当各组椎间融合器受压丢失椎间融合器高度1/3时即判定为椎间融合器失效,记录椎间融合器的轴向压缩栽荷及其刚度。若未达到丢失高度1/3时即发生椎间融合器损毁的,记录损毁时的位移、轴向压缩栽荷及其刚度。结果 MPC cage组压缩损毁时丢失的高度明显小于PEEK cage组及髂骨块cage组,差异有显著统计学意义(0.01);MPC cage组压缩损毁时所承受载荷明显高于PEEK cage组及髂骨块cage组丢失高度1/3时所承受载荷,差异存在显著统计学意义(0.01);MPC cage自身刚度远远高于PEEK cage及髂骨块cage,差异存在显著统计学意义(0.01)。结论磷酸镁可降解椎间融合器(MPC cage)具有优良的抗形变能力及能够承受较大的压力载荷,能够提供人体腰椎间隙的支撑-压缩稳定作用,能满足临床植入的生物力学要求。     

Soft tissue anatomy around the hip and its implications for choice of entry point in antegrade femoral nailing

Antegrade intramedullary nailing is an accepted method of treatment for femoral shaft fractures. Entrance of the nail through the trochanteric fossa is currently recommended by some surgeons. This approach results in some cases, however, in loss of abduction strength and persistent pain. Nail insertion at the tip of the greater trochanter may be more favorable. In this study the anatomical relationships of the trochanteric fossa and of the tip of the greater trochanter were explored. Dissection was carried out in 10 fresh human cadaver femurs. The risks and safety of the two entry points with respect to the adjacent soft tissues were assessed. Abductor muscles and tendons, branches of the medial circumflex femoral artery and the hip joint capsule were at risk during nail insertion through the trochanteric fossa. These structures were not endangered during insertion through the trochanteric tip. The reported clinical morbidity after nailing through the trochanteric fossa may result from direct soft tissue injury and may be reduced by choosing the route through the greater trochanter.     

In vitro biomechanical study of femoral torsion disorders: effect on tibial proximal epiphyseal cancellous bone deformation

Purpose  

Osteoarthritis (OA) of the knee is a degenerative disease mainly found in elderly population. Valgus deformity seems to be directly related to lateralised gonarthrosis. Contradictory outcomes of surgical series are published in the literature and report satisfactory and unsatisfactory long-term results. Lower limb torsions disorders have been considered as being another factor inducing gonarthrosis. This paper presents an in vitro study aiming at quantifying the relationships between experimental femoral torsion disorders (medial and lateral) and the deformation of the cancellous bone of the proximal tibial epiphysis (CB_TPE).     

In vitro evaluation of left ventricular assistance by cannulation of both femoral arteries

The possibility of achieving effective mechanical ventricular assistance without the need for thoracotomy provides great clinical advantages. Two in vitro systems were used to assess left ventricular unloading by means of a small-diameter cannula inserted retrograde into the left ventricle by cannulation of the femoral artery. This cannula is connected to the inlet of a centrifugal blood pump (CP) that delivers the blood into the contralateral femoral artery. Steady-flow test circulation was used to pump fluid in a closed loop from a reservoir through the test cannula back into the reservoir. Pressure drops over cannulae with inner diameters of 4, 5, 6, 7, and 8 mm at flows of 2, 2.5, 3 L/min, against a pressure of 60, 80, 100, and 120 mmHg were calculated. A stationary pressure drop of 120 mmHg was measured at a flow of 3 L/min through a 100 cm cannula with an inner diameter of 6 mm. The second system was a pulsatile mock circulation composed of an atrial and an arterial reservoir linked by a pneumatic prosthetic ventricle. This system was coupled with a 100 cm cannula, 6.1 mm inner diameter, which was passed across the outflow valve of the pulsatile prosthetic ventricle and connected to a CP. Fluid was withdrawn from the ventricle and pumped back into the arterial reservoir. Pulsatile pressure drop over the cannula was measured at different CP flows for increasing systolic ventricular pressure; heart unloading was quantified as a function of CP flow under baseline and failing conditions of the prosthetic left ventricle model. At a constant CP flow the pressure drop over the cannula increased with the pulsatility inside the ventricle. The work of the prosthetic ventricle was reduced by more than 50% when the CP pump was set to 3 L/min; at the same flow setting, when the situation of a failing left ventricle was simulated, the CP was able to take over all the work of the prosthetic ventricle, establishing a stationary flow and a 25% higher mean aortic pressure. This approach to left ventricular assistance may have significant clinical relevance.     

In vitro translation of immediate early, early, and late classes of RNA from vaccinia virus-infected cells.

Cytoplasmic RNA, isolated at various times after vaccinia virus infection, was translated in a message-dependent cell-free system prepared from rabbit reticulocytes. Supplementation of the system with calf liver tRNA specifically increased translation of viral RNA. Virtually all of the [³⁵S]methionine-labeled viral proteins from infected cells that were detected by sodium dodecyl sulfate -polyacrylamide gel electrophoresis appeared to be synthesized in the cell-free system. When programmed with RNA extracted at 2 hr after infection, early viral proteins were made and formation of cellular proteins was diminished. Primarily late proteins were synthesized using RNA extracted at 4 or more hr after infection, suggesting that the switch in protein synthesis is regulated principally by changes in RNA concentration rather than by modification of the translation apparatus of the cell. However, the vaccinia virus-mediated inhibition of host protein synthesis that occurred in the presence of actinomycin D was not associated with a decrease in translatable cellular mRNA. Immediate early RNA and early RNA were obtained by infecting cells in the presence of inhibitors of protein and of DNA synthesis, respectively. Analysis of the in vitro translation products did not reveal a class of early genes that require protein synthesis for expression. On the contrary, seven polypeptides, of which a 28,000-dalton species was most prominent, were synthesized in relatively greater amounts with immediate early RNA than with early RNA. All early and late mRNA species appear to be polyadenylylated, and a correlation between RNA sedimentation and molecular weight of translation product was obtained.     

Differential induction of sister chromatid exchanges by indirect-acting mutagen-carcinogens at early and late stages of embryonic development

To examine the development of drug-metabolizing enzyme systems in the early chick embryo, the procarcinogens, aflatoxin B₁ (AF-B₁) and 2-acetylamino-fluorene (2-AAF), and the direct-acting carcinogen, ethyl methanesulfonate (EMS) (positive control), were given to embryos; the sister-chromatid-exchange (SCE) technique was used as an indicator of conversion to active mutagenic metabolities. Chick embryos at two stages of incubation (3-day and 6-day) were exposed to the same graded series of dosages of the compounds for a period of 22 hours. All three mutagens increased the frequency of SCE above the control rate of 1.8 SCEs/cell. While a dose-dependent increase in SCE was obtained for both procarcinogens at each age, the mean SCE frequency was significantly higher in the 6-day embryos for each dosage given. In contrast, the direct-acting mutagen, EMS, gave a reduced level of SCEs at the older age. These results suggest that the ability of early chick embryos to activate promutagens to forms capable of inducing SCE increases as development advances from three to six days of incubation (DI). In the 6-day embryo, the metabolic conversion is enhanced, resulting in a significant increase in the mutagenicity of the test chemicals.     

In situ expression of fibrogenic growth factors and their receptors in biliary atresia: comparison between early and late stages

Progressive fibrosis, despite successful surgical treatment, is one of the serious complications of biliary atresia. To understand the mechanism of this fibrosis, the in situ expression of fibrogenic growth factors (TGF-beta and PDGF) and their corresponding receptors was studied by immunohistochemistry using frozen sections. The results were compared between the early (n=12) and late (n=6) stages. The early stage was characterized by abundant expression of all ligands and receptors, together with type I procollagen (PC-I). The major cellular sources were activated fibroblasts/myofibroblasts distributed mostly in the portal tracts. Macrophages also expressed all the ligands and the receptors, but to a lesser degree. Bile duct cells strongly expressed TGF-beta RI and RII and PDGF AA and BB, but focally expressed TGF-beta. All of these decreased in the late stage of biliary atresia. These results suggest that TGF-beta and PDGF play important roles in the fibrogenesis of biliary atresia, especially in its early stage, acting either by autocrine or paracrine mechanisms involving activated fibroblasts/myofibroblasts, bile duct cells, and macrophages.     

Testicular morphology in the early and late stages of prostatic cancer]

A total of 31 biopsy specimens in patients with cancer of the prostate (18 with I and II stages and 13 with III and IV stages of the disease) were investigated. The results obtained were collated with those of the control group (22 observations). Involutional changes in the testes in the patients with cancer of the prostate started earlier and were more pronounced than those in the corresponding age of the control group. The testes in the patients with cancer were characterized by a specific mucoid oedema of the intertubular stroma with outcome into sclerosis. At early stages of the cancer hyperplasia and hypertrophy of Leydig' cells were noted. At final stages of the diseases their number normalized. At the same time the number of Sertoli's cells increased and signs indicating to intensification of their activity appeared.     

非透视下确定顺行股骨髓内钉大转子进钉点的解剖观察及临床应用

目的 探讨非透视下确定顺行股骨髓内钉大转子进钉点的技术方法。方法 2007年12月—2008年6月选取10%甲醛溶液固定的成人髋部湿标本8具,男5例、女3例,观察股骨大转子解剖特征,标记大转子上臀中肌、梨状肌的附着情况,观察股骨大转子嵴拐点凹陷、髓腔中轴线与梨状窝的解剖关系。2010年1月—2012年12月对收治的44例股骨转子间及股骨干骨折患者进行前瞻性研究。其中男20例,女24例;年龄25～85岁,平均 (66.9± 15.7)岁。患者均行顺行髓内钉固定术,术中根据标本解剖中发现大转子嵴拐点凹陷和梨状窝的关系,非透视下通过手法触摸确定髓内钉开口位置。结果 尸体标本解剖研究发现,股骨大转子在与股骨颈结合部形成一个向外侧凸出类似“C”形的山嵴样结构。股骨大转子嵴呈后方高、前方平坦下降似斜坡样结构,中间凭借手指就可以感觉有一个类似拐点的凹陷切迹。臀中肌附着在大转子嵴的外侧部分,梨状肌腱附着在大转子嵴拐点切迹的内侧部分。梨状窝就是梨状肌附着点的骨质凹陷,梨状窝基本位于髓腔中轴线上、大转子嵴拐点凹陷的内侧。44例患者中,1例患者术中无法满意确定骨折近端髓腔朝向,开口过程中采用X线透视检查髓腔开口器的方向;43例均在非透视的情况下将髓内钉导针置入髓腔,髓内钉均置入良好。术后随访时间9～28个月,平均18.4个月;除1例股骨干骨折愈合迟缓,动力化后愈合外,其他患者均愈合良好;随访期间所有患者无髓内钉松动、股骨头切出等并发症。结论 在股骨干和股骨转子区骨折采用顺行髓内钉固定治疗术中,非透视下通过手法触摸,可以利用大转子嵴拐点凹陷切迹代替梨状窝参考定位,确定髓内钉开口位置,避免反复透视,降低辐射损害。     

人工颈椎间盘置换术与融合术的生物力学比较

目的 分析颈前路植骨融合术（anterior cervical discectomy and fusion,ACDF）与颈椎间盘置换术（total disc replacement,TDR）后颈椎生物力学特性。方法 采用12具人体颈椎标本,通过三维非接触式光电测量系统及位移控制方式,测试原始状态（intact）、TDR及ACDF术后各节段在前屈与后伸、左侧弯与右侧弯、左旋转与右旋转6种独立工况的运动和载荷分布,并探讨颈椎正常生理运动规律及植入器械特点。结果TDR术后,颈椎各节段运动保留效果明显,能恢复接近正常的运动,并以屈伸、旋转工况为优;同等工况下ACDF术后手术节段运动丢失达73.41%,其他节段运动也存在明显改变。侧弯工况两者均存在较大运动改变,TDR达45.92%,ACDF达108.06%。试验发现,颈椎正常生理运动为空间三轴耦合运动,以侧弯工况耦合程度最大,绕X轴运动分量达35%,TDR术后,颈椎能恢复接近正常的耦合运动规律。结论TDR术能使颈椎恢复更接近正常的生理运动,在屈伸、旋转工况效果最好,侧弯次之。本研究为TDR与ACDF的临床手术提供理论依据和定量参考。     

Amantadine hydrochloride inhibition of early and late stages of lymphocytic choriomeningitis virus-cell interactions

Amantadine hydrochloride inhibits the CA1371, UBC, and WE strains of LCM in both BHK21/13S and L-929 cells. The compound has no direct inactivating effect on virus infectivity nor does it affect the adsorption of virus to cells. By observing the susceptibility of cell-adsorbed virus to neutralizing antibody, amantadine was shown to delay virion penetration. Furthermore, addition of the drug at any time during ongoing viral replication, with all cells scoring as infective centers, inhibits virus synthesis and release.     

Kinetics of the uptake of rifampicin and tetracycline into mouse macrophages. In vitro study of the early stages

The in vitro uptake by mouse peritoneal macrophages, of chlortetracycline (by fluorescence microscopy) and of tetracycline and rifampicin (by scintillation spectrometry of radioactive antibiotics) has been studied over a six hours period, using various concentrations of the antibiotics, close to the therapeutic concentrations. The incidence of the conditions of the assays, especially that of the use of heterologous serum for the cultivation of cells, has been investigated; a medium supplemented with homologous serum at low concentration has been devised with the technique. The uptake of these antibiotics was a three-phases process suggesting the superposition to a passive diffusion of either an active incorporation, or a restriction of the outflow (perhaps associated). This led to a rather high concentration of the antibiotics into cells, although other studies have shown that this concentration is not as active on intracellular bacteria as one could expect from the in vitro sensitivity.     

In vitro characterization and biomechanical optimization of a biodegradable particulate composite bone cement

We have developed a biodegradable particulate composite bone cement and used in vitro and in vivo methods for studying its suitability for orthopaedic applications. The composite matrix consists of gelatin, water, and sodium salicylate. The particulate phase is made up of powdered and particulate (355-600 microns diameter) tricalcium phosphate. Paraformaldehyde (0.1% to 0.5% by weight) is used as a matrix cross-linking agent. The effects of incubation time, particulate volume fraction, density of the individual particles, water content, concentration of crosslinking agent, and freeze-drying on the unconfined compressive strength and modulus of the particulate composite were measured. Compressive strengths of 7 MPa and moduli of 65 MPa could be achieved. Mechanical properties depended critically upon the water content of the particulate composite, with values of strength and modulus decreasing rapidly outside a range of 10-14% of specimen dry weight. High-density tricalcium phosphate particulate produced cement with twice the strength found with porous particulate. In a companion study we document in vivo performance of this particulate composite in an animal model system.     

Changes in the liver of rats at late stages of regeneration

Summary The author carried out a histological study of the regenerating liver of rats at remote periods (2, 5, 11 and 17 months) after the operation.Development of dystrophic processes was observed 17 months after the excision of 2/3 of the organ by Higgins and Anderson's method. The weight of the liver decreased in experimental animals and was much lower than in controls. A large number of binuclear cells with small nuclei appeared; mononuclear hepatic cells decreased in size; proliferation and thickening of reticular fibers was detected by Gomori's staining.(Presented by Active Member of the Akad. Med. Nauk SSSR N. N. Zhukov-Verezhnikov) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 51, No. 4, pp. 114–118, April, 1961     

In vitro metabolism of moxidectin in Haemonchus contortus adult stages

We studied the implication of cytochrome P450 enzymes in the in vitro metabolism of moxidectin (MXD) in homogenates of Haemonchus contortus adult stages (susceptible isolate, Weybridge, UK). After homogenisation in a phosphate buffer, 2 ml of homogenates (equivalent to 1 g of nematodes) were incubated with 5 microg [14C] MXD at 37 degrees C for 24 h. MXD and its metabolites were separated by HPLC with radiodetection on-line. Only one metabolite was detected and its production was inhibited by carbon monoxide. This result demonstrates that the cytochrome P450 system is implicated in the metabolisation of MXD in H. contortus susceptible to milbemycin. Furthermore, this metabolite did not match those previously described in vertebrates.     

Tracking early and late stages of information processing: Contributions of startle eyeblink reflex modification

Startle eyeblink modification was examined as a measure of information processing. College students were presented with tones of 5 and 7 s duration of either high or low pitch, followed by startle-eliciting stimuli at lead intervals of 120, 2.000, 4,500, or 6,000ms. Attention to tones was manipulated by instructing the task group to count the longer tones of either pitch. The no-task group had no instructed task. Startle eyeblink was inhibited at the short lead interval and facilitated at the long lead intervals in both groups. The task group showed greater inhibition and facilitation during attended than during ignored tones, indicating that early and late controlled processing was occurring. In the task group, I he degree of facilitation appeared to reflect the degree of cognitive demands of the task. Startle eyeblink modification may provide a sensitive measure of the nature and timing of stapes of processing in active and passive attentional conditions.     

Differential activation of monkey striatal neurons in the early and late stages of procedural learning

The magnetic properties of human hippocampal tissue from 23 subjects (15 epilepsy patients and eight cadavers with no neuropathology) were analysed and tissue concentrations of magnetic material were calculated. The biogenic iron oxide magnetite (Fe(3)O(4)) is the dominant source of magnetisation in the tissue. Analysis of the group as a whole revealed no significant trend towards either increasing or decreasing magnetite concentration with age. Separate analysis of male and female subjects, however, reveals a trend towards increasing magnetite concentration with age in males. This trend is not seen in females and may have implications for iron metabolism and neurological disorders associated with disruptions in normal iron homeostasis.     

In vitro culture of intramolluscan stages of the avian schistosomeTrichobilharzia ocellata

Several different procedures for in vitro cultivation of intramolluscan stages of the avian schistosomeTrichobilharzia ocellata were tried. A medium was found and culture conditions were established that not only supported in vitro transformation of miracidia into mother sporocysts, but also resulted in substantial subsequent growth; moreover, some degree of germinative development appeared to occur as well. Cerebral ganglia from uninfected adult snails of the intermediate host species,Lymnaea stagnalis, could produce factors promoting in vitro development of young mother sporocysts. Results are compared with data from the literature and it is concluded that greater success in in vitro culturing of young mother sporocysts ofT. ocellata can be achieved than has hitherto been reported for other schistosome species. The same culture procedures were less successful when applied to other intramolluscan stages ofT. ocellata, but can be used for in vitro maintenance of these stages. The procedures described here will be a useful tool in the study of schistosome-snail interactions inT. ocellata-L. stagnalis and possibly in other systems as well.