Local Application of Strontium in a Calcium Phosphate Cement System Accelerates Healing of Soft Tissue Tendon Grafts in Anterior Cruciate Ligament Reconstruction: Experiment Using a Rabbit Model

Background: The healing of soft tissue tendon graft within the bone tunnel in anterior cruciate ligament (ACL) reconstruction is known to be slower than that of bone-patellar tendon-bone graft. There are attempts in accelerating the healing of the graft within the bone tunnel. One of the methods is the use of strontium-enriched calcium phosphate bone cement (Sr-CPC). The early result in animal study was encouraging, though it was not known whether the accelerated healing was solely due to the effect of the strontium within the cement, or due to the calcium phosphate cement (CPC) itself. Hypothesis: There would be differences between a strontium-enriched calcium phosphate cement (Sr-CPC) and a conventional calcium phosphate cement (CPC) in terms of the effect on soft tissue tendon graft healing within the bone tunnels in anterior cruciate ligament (ACL) reconstruction. Study Design: Controlled laboratory study. Methods: Thirty single bundle ACL reconstruction procedures were performed in 15 rabbits with the use of an Achilles tendon allograft. The graft on the left limb was coated with Sr-CPC, while that on the right limb was coated with CPC. Three animals were sacrificed for histological and histomorphometric analysis at 3, 6, 9, 12 and 24 weeks post-operation. Results: In the Sr-CPC group, early Sharpey fiber formation was present at 6 weeks post-operation while early remodeling of a graft-fibrocartilage-bone junction was noted at 12weeks. In the CPC group, early Sharpey fiber formation was only found at 9 to 12 weeks post-operation. At 24 weeks, a direct enthesis was found in both groups. According to histomorphometric score, graft healing in the Sr-CPC group took place 3 weeks faster than that in the CPC group at and before 12 weeks, but there was no difference at 24 weeks. Conclusion: The local application of strontium in a CPC system leads to accelerated graft healing within the bone tunnels. Clinical Relevance: The use of Sr-CPC to enhance graft-bone healing may improve the clinical results of ACL reconstruction using soft tissue tendon graft. Keywords: anterior cruciate ligament (ACL); strontium; calcium phosphate cementpostprin

Use of strontium-enriched bioactive bone cement in enhancing tendon osteointegration in a rabbit anterior cruciate ligament reconstruction model

Conference Theme: Defying the Aging Spine: Our Mission ContinuesConcurrent Free Papers 5 - Sports: no. 5.17Introduction: It was hypothesised that strontium led to accelerated healing of strontium-enriched calcium phosphate cement (Sr-CPC)–treated soft tissue tendon graft within the bone tunnel in anterior cruciate ligament (ACL) reconstruction. This hypothesis was tested in a rabbit ACL reconstruction model using Achilles tendon allograft. Methods: A total of 30 bilateral ACL reconstructions were performed in 15 rabbits. The graft on the tested limb was treated with Sr-CPC, while that on the contralateral limb was treated with CPC. Three were sacrificed for histomorphometric analysis respectively at 3, 6, 9, 12, and 24 weeks after the index operation. Histomorphometric analysis of the healing of graft was done by 2 independent observers in 42 histological zones per animal using a scoring system of 0 to 9. The data were analysed by Mann-Whitney U test. Results: Accelerated healing of the graft within bone tunnel was noted in the strontium-treated limb at 3, 6, 9, and 12 weeks after the operation (p < 0.001) when compared with the CPC-treated limb. Complete healing of the graft by Sharpey’s fibre formation at 9 weeks and early evidence of remodelling into normal ACL insertion site at 12 weeks were noted in the SrCPC group. The healing of the graft in the CPC-treated limb was noted 3 to 6 weeks slower than the Sr-CPC group. Conclusion: Strontium is the main contributing factor leading to accelerated healing of Sr-CPC–treated soft tissue tendon graft in a rabbit ACL reconstruction model.postprin

Use of strontium-enriched bioactive bone cement in enhancing tendon osteointegration in a rabbit anterior cruciate ligament reconstruction model

Conference Theme: Defying the Aging Spine: Our Mission ContinuesConcurrent Free Papers 5 - Sports: no. 5.17Introduction: It was hypothesised that strontium led to accelerated healing of strontium-enriched calcium phosphate cement (Sr-CPC)–treated soft tissue tendon graft within the bone tunnel in anterior cruciate ligament (ACL) reconstruction. This hypothesis was tested in a rabbit ACL reconstruction model using Achilles tendon allograft. Methods: A total of 30 bilateral ACL reconstructions were performed in 15 rabbits. The graft on the tested limb was treated with Sr-CPC, while that on the contralateral limb was treated with CPC. Three were sacrificed for histomorphometric analysis respectively at 3, 6, 9, 12, and 24 weeks after the index operation. Histomorphometric analysis of the healing of graft was done by 2 independent observers in 42 histological zones per animal using a scoring system of 0 to 9. The data were analysed by Mann-Whitney U test. Results: Accelerated healing of the graft within bone tunnel was noted in the strontium-treated limb at 3, 6, 9, and 12 weeks after the operation (p < 0.001) when compared with the CPC-treated limb. Complete healing of the graft by Sharpey’s fibre formation at 9 weeks and early evidence of remodelling into normal ACL insertion site at 12 weeks were noted in the SrCPC group. The healing of the graft in the CPC-treated limb was noted 3 to 6 weeks slower than the Sr-CPC group. Conclusion: Strontium is the main contributing factor leading to accelerated healing of Sr-CPC–treated soft tissue tendon graft in a rabbit ACL reconstruction model.postprin

Endoscopic submucosal dissection vs laparoscopic colorectal resection for early colorectal epithelial neoplasia

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促進前交叉韌帶重建術後腱-骨愈合的方法學進展

近年来,应用肌腱移植物(如腘绳肌腱)行前交叉韧带重建术越来越普遍。手术的远期疗效关键取决于肌腱移植物能否在骨隧道内获得可靠的腱-骨愈合,腱-骨界面开始仅通过一些Sharpey样纤维连接,其在力学上逊于正常的纤维软骨连接,之后肌腱移植物在骨隧道内需要相当长时间才能获得可靠的腱-骨愈合。因此,在没有获得可靠的腱-骨愈合前,腱-骨界面被认为是'弱点',肌腱移植物容易产生滑移甚至从骨隧道内拔出,最终导致手术失败。因此,如何促进腱-骨愈合是目前研究的热点。本文对相关文献做一综述,重点关注应用于骨隧道局部的一些方法学进展。其中干细胞技术、生长因子的局部应用、基因转染技术以及炎症反应的生物调控技术等均已获得令人振奋的研究成果。生物活性骨水泥的应用以及物理治疗方法也取得可喜的成果。组织工程技术可能成为降低供区并发症的方法 ,尽管目前的研究成果令人鼓舞,但仅基于动物实验,应用于临床实践尚需进一步随机对照临床研究

Validation of Statistical Models for Estimating Hospitalization Associated with Influenza and Other Respiratory Viruses

BACKGROUND: Reliable estimates of disease burden associated with respiratory viruses are keys to deployment of preventive strategies such as vaccination and resource allocation. Such estimates are particularly needed in tropical and subtropical regions where some methods commonly used in temperate regions are not applicable. While a number of alternative approaches to assess the influenza associated disease burden have been recently reported, none of these models have been validated with virologically confirmed data. Even fewer methods have been developed for other common respiratory viruses such as respiratory syncytial virus (RSV), parainfluenza and adenovirus. METHODS AND FINDINGS: We had recently conducted a prospective population-based study of virologically confirmed hospitalization for acute respiratory illnesses in persons <18 years residing in Hong Kong Island. Here we used this dataset to validate two commonly used models for estimation of influenza disease burden, namely the rate difference model and Poisson regression model, and also explored the applicability of these models to estimate the disease burden of other respiratory viruses. The Poisson regression models with different link functions all yielded estimates well correlated with the virologically confirmed influenza associated hospitalization, especially in children older than two years. The disease burden estimates for RSV, parainfluenza and adenovirus were less reliable with wide confidence intervals. The rate difference model was not applicable to RSV, parainfluenza and adenovirus and grossly underestimated the true burden of influenza associated hospitalization. CONCLUSION: The Poisson regression model generally produced satisfactory estimates in calculating the disease burden of respiratory viruses in a subtropical region such as Hong Kong

Presynaptic actions of 4-Aminopyridine and γ-aminobutyric acid on rat sympathetic ganglia in vitro

Responses to bath-applications of 4-aminopyridine (4-AP) and -aminobutyric acid (GABA) were recorded intracellularly from neurones in the rat isolated superior cervical ganglion. 4-aminopyridine (0.1–1.0 mmol/l) usually induced spontaneous action potentials and excitatory postsynaptic potentials (EPSPs), which were blocked by hexamethonium. Membrane potential was unchanged; spike duration was slightly increased. Vagus nerve B-and C-fibre potentials were prolonged. In 4-AP solution (0.1–0.3 mmol/l), GABA (0.1 mmol/l), 3-aminopropanesulphonic acid or muscimol evoked bursts of spikes and EPSPs in addition to a neuronal depolarization. These bursts, which were not elicited by glycine, glutamate, taurine or (±)-baclofen, were completely antagonised by hexamethonium, tetrodotoxin or bicuculline methochloride. It is concluded that: (a) 4-AP has a potent presynaptic action on sympathetic ganglia; (b) presynaptic actions of GABA can be recorded postsynaptically in the presence of 4-AP; and (c) the presynaptic GABA-receptors revealed in this condition are similar to those on the postsynaptic membrane

Model Selection in Time Series Studies of Influenza-Associated Mortality

Background: Poisson regression modeling has been widely used to estimate influenza-associated disease burden, as it has the advantage of adjusting for multiple seasonal confounders. However, few studies have discussed how to judge the adequacy of confounding adjustment. This study aims to compare the performance of commonly adopted model selection criteria in terms of providing a reliable and valid estimate for the health impact of influenza. Methods: We assessed four model selection criteria: quasi Akaike information criterion (QAIC), quasi Bayesian information criterion (QBIC), partial autocorrelation functions of residuals (PACF), and generalized cross-validation (GCV), by separately applying them to select the Poisson model best fitted to the mortality datasets that were simulated under the different assumptions of seasonal confounding. The performance of these criteria was evaluated by the bias and root-mean-square error (RMSE) of estimates from the pre-determined coefficients of influenza proxy variable. These four criteria were subsequently applied to an empirical hospitalization dataset to confirm the findings of simulation study. Results: GCV consistently provided smaller biases and RMSEs for the influenza coefficient estimates than QAIC, QBIC and PACF, under the different simulation scenarios. Sensitivity analysis of different pre-determined influenza coefficients, study periods and lag weeks showed that GCV consistently outperformed the other criteria. Similar results were found in applying these selection criteria to estimate influenza-associated hospitalization. Conclusions: GCV criterion is recommended for selection of Poisson models to estimate influenza-associated mortality and morbidity burden with proper adjustment for confounding. These findings shall help standardize the Poisson modeling approach for influenza disease burden studies. © 2012 Wang et al.published_or_final_versio

Reliability characteristics and conduction mechanisms in resistive switching memory devices using ZnO thin films

In this work, bipolar resistive switching characteristics were demonstrated in the Pt/ZnO/Pt structure. Reliability tests show that ac cycling endurance level above 106 can be achieved. However, significant window closure takes place after about 102 dc cycles. Data retention characteristic exhibits no observed degradation after 168 h. Read durability shows stable resistance states after 106 read times. The current transportation in ZnO films is dominated by the hopping conduction and the ohmic conduction in high-resistance and low-resistance states, respectively. Therefore, the electrical parameters of trap energy level, trap spacing, Fermi level, electron mobility, and effective density of states in conduction band in ZnO were identified

Identification of a Cryptic Prokaryotic Promoter within the cDNA Encoding the 5′ End of Dengue Virus RNA Genome

Infectious cDNA clones of RNA viruses are important research tools, but flavivirus cDNA clones have proven difficult to assemble and propagate in bacteria. This has been attributed to genetic instability and/or host cell toxicity, however the mechanism leading to these difficulties has not been fully elucidated. Here we identify and characterize an efficient cryptic bacterial promoter in the cDNA encoding the dengue virus (DENV) 5′ UTR. Following cryptic transcription in E. coli, protein expression initiated at a conserved in-frame AUG that is downstream from the authentic DENV initiation codon, yielding a DENV polyprotein fragment that was truncated at the N-terminus. A more complete understanding of constitutive viral protein expression in E. coli might help explain the cloning and propagation difficulties generally observed with flavivirus cDNA