A Robot-Assisted Surgical System Using a Force-Image Control Method for Pedicle Screw Insertion

Objective

To introduce a robot-assisted surgical system for spinal posterior fixation that can automatically recognize the drilling state and stop potential cortical penetration with force and image information and to further evaluate the accuracy and safety of the robot for sheep vertebra pedicle screw placement.

Methods

The Robotic Spinal Surgery System (RSSS) was composed of an optical tracking system, a navigation and planning system, and a surgical robot equipped with a 6-DOF force/torque sensor. The robot used the image message and force signals to sense the different operation states and to prevent potential cortical penetration in the pedicle screw insertion operation. To evaluate the accuracy and safety of the RSSS, 32 screw insertions were conducted. Furthermore, six trajectories were deliberately planned incorrectly to explore whether the robot could recognize the different drilling states and immediately prevent cortical penetration.

Results

All 32 pedicle screws were placed in the pedicle without any broken pedicle walls. Compared with the preoperative planning, the average deviations of the entry points in the axial and sagittal views were 0.50±0.33 and 0.65±0.40 mm, and the average deviations of the angles in the axial and sagittal views were 1.9±0.82° and 1.48±1.2°. The robot successfully recognized the different drilling states and prevented potential cortical penetration. In the deliberately incorrectly planned trajectory experiments, the robot successfully prevented the cortical penetration.

Conclusion

These results verified the RSSS’s accuracy and safety, which supported its potential use for the spinal surgery.     

经皮RTS钉固定与常规椎弓根固定在胸腰段压缩骨折中的疗效比较

目的:分析和比较使用经皮RTS钉固定与常规椎弓根固定在胸腰段骨折中的临床疗效和安全性。方法:对2017年6月至2018年6月在我院住院,经诊断为胸腰段骨折,且经纳入及排除标准筛选后的共计74例患者进行回顾性分析。根据不同的手术方式和选择,将纳入的患者分为经皮RTS钉固定组(观察组;40例)和常规椎弓根螺钉固定组(对照组;34例)。在术后的3天,1月及1年比较两组患者的疼痛评分及功能评分;并通过其影像学指标(伤椎高度恢复,cobb角恢复等)比较两组的影像学疗效;比较两组患者的手术时间,出血量,切口长度等手术指标;比较两组患者的并发症等情况。结果:在术后3天时,观察组患者的VAS评分显著优于对照组(P0.05),而在术后1月及1年时,两组患者未见显著差异(P0.05)。两组患者的Cobb角及前缘高度百分比较术前均有显著改善(P0.05),且两组间均有显著差异(P0.05)。两组患者在手术时间,切口长度,透视次数,出血量,出院时间等均有显著差异(P0.05)。两组患者在并发症的比较中并无统计学差异(P0.05)。结论:与常规的开放椎弓根螺钉固定相比,对于胸腰椎压缩骨折,RTS螺钉能够有效的恢复影像学指标,特别是在前缘高度及Cobb角恢复,并且能够有效地减少创伤及出血,加快功能恢复,在临床中可以进一步推广。     

经伤椎椎弓根置钉椎体内植骨对胸腰椎骨折的疗效评价

目的:对比探讨经伤椎椎弓根置钉椎体内植骨与常规跨伤椎后路复位内固定对胸腰椎骨折的治疗方法及效果.方法:选取我院近期确诊收治的66名胸腰椎骨折患者分为两组,其中实验组36名经伤椎椎弓根置钉椎体内植骨,对照组30名行常规跨伤椎后路复位内固定,随访期间对比两组患者的临床疗效(优良率),手术时间、术中血量、伤椎前高压缩比、Cobb角、椎管侵占率等 临床指标,及Frankel分级变化.结果:治疗后,所有患者的Frankel分级及生活质量均优于治疗前(P＜0.05),而两组间相比,实验组的临床疗效及指标均优于对照组(P＜0.05).结论:经伤椎椎弓根置钉椎体内植骨治疗胸腰椎骨折,符合生物力学特征,可有效改善患者的临床症状及体征,且安全性高,值得推广.     

自体髂骨移植用于后路椎弓根钉棒系统矫形内固定术治疗脊柱侧凸的临床效果及对预后的影响

目的:探讨自体髂骨移植用于后路椎弓根钉棒系统矫形内固定术治疗脊柱侧凸的临床效果及对患者预后的影响。方法:选取2014年4月至2017年4月90例在我院及山西医科大学进行手术治疗的退行性脊柱侧凸患者作为研究对象,按照随机法将患者分为两组,各组45例患者。对照组采用后路椎弓根钉棒系统矫形内固定术,观察组采用后路椎弓根钉棒系统矫形内固定结合自体髂骨移植术。比较两组患者围手术期情况,术前、术后7天及术后12个月腰椎后凸角度、Cobb角、JOA评分、ODI评分的变化及术后并发症发生情况。结果:两组患者手术时间、术中出血量、体温恢复时间、WBC恢复正常时间、引流管置管时间比较差异无统计学意义(P0.05)。两组患者术后腰椎前凸角度、Cobb角较手术前明显改善(P0.05);术后12个月,观察组患者腰椎前凸角度高于对照组,Cobb角显著低于对照组(P0.05)。两组患者术后JOA评分高于手术前,ODI评分低于手术前(P0.05);观察组患者术后12个月JOA评分高于对照组,ODI评分低于对照组(P0.05)。观察组患者并发症发生率显著低于对照组(P0.05)。结论:自体髂骨移植应用于后路椎弓根钉棒系统矫形内固定术治疗退行性脊柱侧弯效果较好,不仅可纠正脊柱侧弯,同时可减轻患者疼痛感及不适感,安全性较高。     

新型骨水泥椎弓根螺钉在治疗腰椎滑脱合并骨质疏松症的应用研究

目的:探讨评估聚甲基丙烯酸甲酯(polymethvlmethacnrlat, PMMA)增强的具有"渐变孔"结构的侧开孔中空椎弓根螺钉(Fenestrated pedicle screw, FPS)治疗腰椎滑脱症的安全性及疗效。方法:回顾性分析2013年1月～2017年12月收治32例合并有骨质疏松症的腰椎滑脱患者,均应用具有"渐变孔"结构的FPS融合手术治疗,记录手术时长、术中出血量,住院时长;测量椎间隙高度、椎体楔形变指数、滑脱距离、滑脱角、骨盆指数、腰椎前凸角;随访评估Oswestry功能障碍指数问卷表(Oswestry Disability Index Questionnaire, ODI)评分和视觉模拟评分法(Visual Analogue Score, VAS)评分,比较分析术前、术后及末次随访时的差异;结果:术中X线及术后三维CT检查发现3枚渗漏的骨水泥螺钉(2.2%),均为Yeom C型,术后无不适。随访7～61个月(平均34.9个月),滑脱复位良好,后凸畸形和矢状位失衡矫正良好,ODI评分和VAS评分均较术前有显著改善(p0.05)。随访期间,全部病例滑脱无复发,无椎弓根螺钉松动、断裂,无椎间隙塌陷,根据SUK标准融合成功率100%。结论:新型骨水泥螺钉能够提供良好的固定稳定性,并且能够避免骨水泥渗漏发生以及螺钉松动脱出,为骨质疏松脊柱手术提供一种新的选择。     

2-Butanol and Butanone Production in Saccharomyces cerevisiae through Combination of a B12 Dependent Dehydratase and a Secondary Alcohol Dehydrogenase Using a TEV-Based Expression System

2-Butanol and its chemical precursor butanone (methyl ethyl ketone – MEK) are chemicals with potential uses as biofuels and biocommodity chemicals. In order to produce 2-butanol, we have demonstrated the utility of using a TEV-protease based expression system to achieve equimolar expression of the individual subunits of the two protein complexes involved in the B₁₂-dependent dehydratase step (from the pdu-operon of Lactobacillus reuterii), which catalyze the conversion of meso-2,3-butanediol to butanone. We have furthermore identified a NADH dependent secondary alcohol dehydrogenase (Sadh from Gordonia sp.) able to catalyze the subsequent conversion of butanone to 2-butanol. A final concentration of 4±0.2 mg/L 2-butanol and 2±0.1 mg/L of butanone was found. A key factor for the production of 2-butanol was the availability of NADH, which was achieved by growing cells lacking the GPD1 and GPD2 isogenes under anaerobic conditions.     

Flavor Specificities of Satsuma Mandarin Juice Extracted by a New-type Screw Press Extraction System

Dextransucrases from Leuconostoc mesenteroides NRRL B-1416 and B-1375 strains were purified to electrophoretically homogeneous preparations. After successive column chromatographies, the enzyme fractions were treated with endodextranase, then subjected to preparative polyacrylamide gel electrophoresis. The purified dextransucrase from each strain had a dimeric structure of molecular weight 130,000~133,000. Alkaline treatment (pH 10.5) dissociated these dimer forms into the respective monomer forms having molecular weight of 64,000~68,000. The two enzymes were closely similar to each other in optimum conditions and thermal and pH stabilities. The purified B-1416 enzyme was activated 4.35-fold by the addition of exogenous dextran (0.5%), while the B-1375 enzyme was activated 2.76-fold. In the absence of exogenous dextran, both enzymes gave 5~10 min lag periods for reaction, which were abolished by the clinical dextran.     

Bias Caused by Using Different Isolation Media for Assessing the Genetic Diversity of a Natural Microbial Population

Abstract The influence of isolation medium on the biodiversity of Burkholderia cepacia strains recovered from the rhizosphere of Zea mays was evaluated by comparing the genetic diversity of isolates obtained by plating serial dilutions of root macerates on the two selective media TB-T and PCAT. From each medium, 50 randomly chosen colonies were isolated. On the basis of the restriction patterns of DNA coding for 16S rRNA (16S rDNA) amplified by means of PCR (ARDRA), all strains isolated from TB-T medium were assigned to the B. cepacia species, whereas among PCAT isolates only 74% were assigned to the B. cepacia species. Genetic diversity among the PCAT and TB-T isolates was evaluated by the random amplified polymorphic DNA (RAPD) technique. The analysis of molecular variance (AMOVA) method was applied to determine the variance component for RAPD patterns. Most of the genetic diversity (90.59%) was found within the two groups of isolates, but an appreciable amount (9.41%) still separated the two groups (P < 0.001). Mean genetic distances among PCAT isolates (10.39) and TB-T isolates (9.36) were significantly different (P < 0.0001). The results indicate that the two different isolation media select for B. cepacia populations with a different degree of genetic diversity. Moreover, a higher degree of genetic diversity was observed among strains isolated from PCAT medium than among those isolated from TB-T medium. Received: 29 April 1999; Accepted: 27 January 2000; Online Publication: 28 August 2000     

Accuracy of Probabilistic Linkage Using the Enhanced Matching System for Public Health and Epidemiological Studies

Background

The Enhanced Matching System (EMS) is a probabilistic record linkage program developed by the tuberculosis section at Public Health England to match data for individuals across two datasets. This paper outlines how EMS works and investigates its accuracy for linkage across public health datasets.

Methods

EMS is a configurable Microsoft SQL Server database program. To examine the accuracy of EMS, two public health databases were matched using National Health Service (NHS) numbers as a gold standard unique identifier. Probabilistic linkage was then performed on the same two datasets without inclusion of NHS number. Sensitivity analyses were carried out to examine the effect of varying matching process parameters.

Results

Exact matching using NHS number between two datasets (containing 5931 and 1759 records) identified 1071 matched pairs. EMS probabilistic linkage identified 1068 record pairs. The sensitivity of probabilistic linkage was calculated as 99.5% (95%CI: 98.9, 99.8), specificity 100.0% (95%CI: 99.9, 100.0), positive predictive value 99.8% (95%CI: 99.3, 100.0), and negative predictive value 99.9% (95%CI: 99.8, 100.0). Probabilistic matching was most accurate when including address variables and using the automatically generated threshold for determining links with manual review.

Conclusion

With the establishment of national electronic datasets across health and social care, EMS enables previously unanswerable research questions to be tackled with confidence in the accuracy of the linkage process. In scenarios where a small sample is being matched into a very large database (such as national records of hospital attendance) then, compared to results presented in this analysis, the positive predictive value or sensitivity may drop according to the prevalence of matches between databases. Despite this possible limitation, probabilistic linkage has great potential to be used where exact matching using a common identifier is not possible, including in low-income settings, and for vulnerable groups such as homeless populations, where the absence of unique identifiers and lower data quality has historically hindered the ability to identify individuals across datasets.     

Assessing pharmacokinetic variability directly induced by drug intake behaviour through development of a feeding behaviour-pharmacokinetic model

Variability in drug intake is increasingly recognized as a major source of variability in drug response. The non-uniform access to medicated feed, influenced by swine individual feeding behaviour, is a determinant of antibiotic exposure, recalling the intrinsic similarity with human compliance to drug regimens. In this paper, we developed a feeding behaviour-pharmacokinetic (FBPK) model of in-feed chlortetracycline (CTC) and established, in a definite way, the effect of feeding behaviour and its induced pharmacokinetic (PK) variability. Based on reported animal behaviour, we mathematically formulated swine feeding behaviour by incorporating its main characteristics: intense feeding periods that repeat on a daily basis and random feeding periods of free access to feed, along with growth stage factors. This behaviour model was then integrated into a PK model of CTC. Moreover, we analysed the effect of each feeding behaviour component and assessed the corresponding PK variability. We have been able to delineate the impact of different feeding behaviour components and characterize the induced PK variability. We have compared different therapeutic assumptions to our model and shown that random features underlying the feeding behaviour have dramatic influence on the PK variability. A practical tool to adopt the dosing regimen in terms of dose and age has been proposed. The method developed here can be generalized to other therapeutic contexts and incorporated into medical practice, particularly to make long-term projections of drug-intake behaviour, to explain possible treatment failure and guide practitioners in adjusting the dosing regimen.     

经伤椎椎弓根螺钉固定治疗脊柱骨折的疗效及对患者疼痛、Cobb角的影响

目的:探讨经伤椎椎弓根螺钉固定治疗脊柱骨折的疗效及对患者疼痛、Cobb角的影响。方法:选择2013年2月至2018年2月我院接诊的脊柱骨折患者80例作为研究对象,以随机数表法分为观察组(n=41)和对照组(n=39)。对照组采用跨伤椎固定治疗,观察组采用经伤椎椎弓根螺钉固定治疗。比较两组患者临床手术指标、日本骨科协会评估治疗(JOA)评分、视觉模拟评分(VAS)、椎体压缩率、Cobb角水平及伤椎椎体高度。结果:观察组患者手术时间、术中出血量及住院时间均显著低于对照组(P0.05);治疗后,两组患者JOA评分、VAS评分均明显改善(P0.05),且观察组患者VAS评分显著低于对照组(P0.05);治疗后,两组患者椎体压缩率、Cobb角水平均明显改善(P0.05),且观察组患者椎体压缩率、Cobb角水平显著低于对照组(P0.05);两组患者治疗前椎体前、后缘高度无明显差异;治疗后,两组患者椎体前、后缘高度均明显改善(P0.05),且观察组患者椎体前、后缘高度显著高于对照组(P0.05)。结论:脊柱骨折患者采用经伤椎椎弓根螺钉固定治疗栓效果显著,可改善患者疼痛、Cobb角水平,值得临床推广。     

Plugging of a Model Rock System by Using Starved Bacteria

The effects of starvation on bacterial penetration through artificial rock cores were examined. Klebsiella pneumoniae was starved in a simple salts solution for a duration of up to 4 weeks. These cell suspensions were injected into sintered glass bead cores, and the resulting reductions in core permeabilities were recorded. Vegetative cell cultures of K. pneumoniae grown in a sodium citrate medium were injected into other, similar cores, and the reductions in core permeabilities were recorded. The starved cell suspensions did not completely block the core pores, whereas the vegetative cultures reduced core permeability to less than 1%. Scanning electron microscopy of core sections infiltrated with either vegetative or starved cells showed that the former produced shallow “skin” plugs and copious amounts of glycocalyx at the inlet face, whereas the latter produced very little glycocalyx and the cells were distributed evenly throughout the length of the core. The use of a DNA assay to produce a cell distribution profile showed that, compared with the vegetative cells, starved bacteria were able to penetrate deeper into the cores. This was due to the smaller size of the cells and the reduction in biofilm production. This ability of starved bacteria to penetrate further into cores than the normal-size vegetative cells can be usefully applied to selective plugging for enhanced oil recovery. To further test the suitability of starved cells for use in selective plugging, the activities of starved cells present within cores were monitored before and after nutrient stimulation. Our data indicate that with nutrient stimulation, the starved cells lose their metabolic dormancy and produce reductions in core permeability due to cell growth and polymer production.     

Assessing the Risk of an Aquaculture Development on Shorebirds Using a Bayesian Belief Model

One of the largest Ramsar-designated wetlands in New Zealand is located at Miranda, in the Hauraki Gulf, at the head of a large sheltered embayment (the Firth of Thames). The habitat is particularly significant in that it supports large populations of nationally important, and Arctic migratory, shorebirds. At present regulatory authorities are processing applications for a new marine farming region in the Firth and both regulators and stakeholders have expressed a desire to investigate possible interactions between the possible marine farms and the Ramsar wetland. The specific objective of this study was therefore to use existing information to investigate the risks of the possible aquaculture activities on the ability of the southern Firth habitats to support shorebirds. The study involved the development of a hazard assessment, and then investigating risk pathways through the use of a Bayesian network model, and a complex systems model. The hazard assessment identified multiple pathways through which the farms may interact with the wetland habitat; including through changes to primary productivity, detrital pathways and sediment dynamics. Furthermore, both the Bayesian network model and complex systems model suggested that the ability of the habitat to support shorebirds is nonlinearly dependent on both the habitat size, and quality; both of which could potentially be influenced by the establishment of the farms.     

Fast and Accurate Registration of the Proximal Femurs in Bilateral Hip Joint Images by Using the Random Sub-Sample Points

Background and ObjectiveAs is known, point clouds representing the objects are frequently used in object registration. Although the objects can be registered by using all the points in the corresponding point clouds of the objects, the registration process can also be achieved with a smaller number of the landmark points selected from the entire point clouds of the objects. This paper introduces a research study focusing on the fast and accurate rigid registration of the bilateral proximal femurs in bilateral hip joint images by using the random sub-sample points. For this purpose, Random Point Sub-sampling (RPS) was analyzed and the reduced point sets were used for an accurate registration of the bilateral proximal femurs in coronal hip joint magnetic resonance imaging (MRI) slices.MethodsIn registration, bilateral proximal femurs in MRI slices were registered rigidly by performing a process consisting of three main phases named as MR image preprocessing, proximal femur registration over the random sub-sample points and MR image postprocessing. In the stage of the MR image preprocessing, segmentation maps of the bilateral proximal femurs are obtained as region of interest (RoI) images from the entire MRI slices and then, the edge maps of the segmented proximal femurs are extracted. In the registration phase, the edge maps describing the proximal femur surfaces are represented as point clouds initially. Thereafter, the RPS is performed on the proximal femur point clouds and the number of points representing the proximal femurs is reduced at different ratios. For the registration of the point clouds, the Iterative Closest Point (ICP) algorithm is performed on the reduced sets of points. Finally, the registration procedures are completed by performing MR image postprocessing on the registered proximal femur images.ResultsIn performance evaluation tests performed on healthy and pathological proximal femurs in 13 bilateral coronal hip joint MRI slices of 13 Legg-Calve-Perthes disease (LCPD) patients, bilateral proximal femurs were successfully registered with very small error rates by using the reduced set of points obtained via the RPS and promising results were achieved. The minimum error rate was observed at RPS rate of 30% as the value of 0.41 (±0.31)% on all over the bilateral proximal femurs evaluated. When the range of RPS rate of 20-30% is considered as the reference, the elapsed time in registration can be reduced by almost 30-40% compared to the case where all the proximal femur points were included in registration. Additionally, it was observed that the RPS rate should be selected as at least 25% to achieve a successful registration with an error rate below 1%.ConclusionIt was concluded from the observed results that a more successful and faster registration can be accomplished by selecting fewer points randomly from the point sets of proximal femurs instead of using all the points describing the proximal femurs. Not only an accurate registration with low error rates was performed, but also a faster registration process was performed by means of the limited number of points that are sub-sampled randomly from the whole point sets.     

Assessing the Viral Fitness of Oseltamivir-Resistant Influenza Viruses in Ferrets,Using a Competitive-Mixtures Model

To determine the relative fitness of oseltamivir-resistant strains compared to susceptible wild-type viruses, we combined mathematical modeling and statistical techniques with a novel in vivo “competitive-mixtures” experimental model. Ferrets were coinfected with either pure populations (100% susceptible wild-type or 100% oseltamivir-resistant mutant virus) or mixed populations of wild-type and oseltamivir-resistant influenza viruses (80%:20%, 50%:50%, and 20%:80%) at equivalent infectivity titers, and the changes in the relative proportions of those two viruses were monitored over the course of the infection during within-host and over host-to-host transmission events in a ferret contact model. Coinfection of ferrets with mixtures of an oseltamivir-resistant R292K mutant A(H3N2) virus and a R292 oseltamivir-susceptible wild-type virus demonstrated that the R292K mutant virus was rapidly outgrown by the R292 wild-type virus in artificially infected donor ferrets and did not transmit to any of the recipient ferrets. The competitive-mixtures model was also used to investigate the fitness of the seasonal A(H1N1) oseltamivir-resistant H274Y mutant and showed that within infected ferrets the H274Y mutant virus was marginally outgrown by the wild-type strain but demonstrated equivalent transmissibility between ferrets. This novel in vivo experimental method and accompanying mathematical analysis provide greater insight into the relative fitness, both within the host and between hosts, of two different influenza virus strains compared to more traditional methods that infect ferrets with only pure populations of viruses. Our statistical inferences are essential for the development of the next generation of mathematical models of the emergence and spread of oseltamivir-resistant influenza in human populations.The neuraminidase (NA) inhibitors are a class of influenza antiviral drugs that are specifically designed to inhibit the enzymatic function of the NA, thereby preventing normal viral replication. Since 1999, two NA inhibitors (NAIs), oseltamivir (Tamiflu) and zanamivir (Relenza), have been shown to be effective for the treatment and prophylaxis of patients infected with not only seasonal influenza, but also highly pathogenic A(H5N1) and the newly emerged A(H1N1) pandemic virus. Prior to 2007, resistance to this class of drugs was considered relatively uncommon, particularly in comparison with the other class of influenza antivirals, the adamantanes, which readily select for viral resistance in treated patients. During early clinical trials, oseltamivir resistance was detected in only 1 to 2% of adults (14) and 5 to 6% of children (33) under treatment, although later studies detected resistance in up to 18% of oseltamivir-treated children (16). In contrast, resistance following zanamivir treatment is rare, with only one reported case observed in an immunocompromised patient (6). Influenza viruses that develop resistance to these drugs typically contain mutations in the NA which, either directly or indirectly, alter the shape of the NA enzymatic site, thereby reducing the ability of the drugs to bind to this specific pocket. One of the most commonly observed mutations in oseltamivir-resistant A(H3N2) viruses is an arginine-to-lysine mutation at residue 292 (R292K) of the NA, while the predominant NA mutation in oseltamivir-resistant A(H1N1) viruses is a histidine-to-tyrosine mutation at residue 274 (H274Y) (N2 NA amino acid numbering, equivalent to residue 275 based on N1 numbering). Both of these mutations have an indirect impact on drug binding, as they affect the ability of the glutamic acid residue at position 276 to reorientate, as required for slow binding by oseltamivir (3). Many mutations that cause NAI resistance also cause reduced NA enzyme activity and, consequently, can compromise viral fitness.Previous studies have demonstrated that viruses with an R292K NA mutation demonstrated compromised growth in vitro (36) and in ferrets were significantly less infectious and did not transmit (9). The replication and transmission fitness of the H274Y mutation has also been studied previously. An H274Y mutant A(H1N1) strain isolated from a patient under oseltamivir treatment demonstrated compromised growth in cell culture compared to a wild-type (WT) virus (13), although a strain carrying the same mutation selected in vitro was found to replicate as well as the wild type (32). The infectivity and transmissibility of an H274Y mutant were found to be restricted in ferrets (13), although a second study demonstrated that transmission of the mutant virus between ferrets was possible, but required a greater viral dose of the mutant compared to the wild type (10). These results suggest that resistant virus variants with the same NA mutation may differ in replication or transmission fitness depending on other viral components. Nevertheless, based on these data and the viral fitness of other resistant mutants, it was believed that NAI-resistant viruses were unlikely to spread throughout the community due to their compromised viral fitness in the absence of drug selective pressure. This was proven incorrect during the Northern Hemisphere 2007-2008 influenza season, when large numbers of oseltamivir-resistant seasonal A(H1N1) viruses with an H274Y mutation were detected in patients who had not been treated with oseltamivir (4, 24). The mutant strain continued to spread to the Southern Hemisphere, such that by late 2008 virtually all circulating seasonal A(H1N1) viruses were oseltamivir resistant (11). The rapid global spread of this strain clearly suggested that the oseltamivir-resistant seasonal A(H1N1) virus had fitness equivalent to or greater than that of the previous oseltamivir-sensitive A(H1N1) strain. The reasons for enhanced viral fitness in this strain, when previous studies demonstrated that the acquisition of an H274Y mutation led to reduced viral fitness, remain unclear but probably involve compensatory mutations or reassortment events which may have improved the hemagglutinin (HA)/NA balance, allowing efficient transmission (5, 26).Experimental methods have been developed to assess the relative fitness of NAI-resistant strains compared with respective wild-type viruses, both in vitro and in vivo. Ferrets have been considered the most appropriate model animal for influenza research, and fitness studies have assessed variables such as minimum dose required to achieve infection, duration of viral shedding, and levels of viral load to allow comparisons between viruses. The guinea pig model has also been previously used to assess the viral fitness of influenza viruses, particularly in comparing the transmissibility of strains via either the contact or aerosol route (2). As an alternative to these traditional approaches, we have investigated a methodology that involves coinfection of ferrets with a mixture of two influenza viruses. Daily monitoring of changes in the relative proportion of those viruses over the course of the infection allows determination of the relative replication fitness of the viruses. Monitoring of recipient ferrets exposed to the infected ferrets enables the relative transmissibility of the viruses (henceforth, the relative transmission fitness) to be determined. In this study, the “competitive-mixtures” methodology was used to assess the relative replication and transmission fitness of an oseltamivir-resistant R292K mutant A(H3N2) virus compared with an oseltamivir-sensitive A(H3N2) wild-type strain and also to asses the relative replication and transmission fitness of an oseltamivir-resistant H274Y seasonal A(H1N1) mutant compared with an oseltamivir-sensitive A(H1N1) wild-type strain. Quantitative estimates for the replication fitness of mutant viruses were determined using a simple mathematical model of within-host viral replication and mixed-effects statistical tests. Transmission fitness was evaluated by application of a graphical technique that demonstrated the relationship between the proportion of mutant virus in the infectee ferrets as a function of the proportion of mutant virus in the infector ferrets.Inferences drawn from the statistical analyses presented here are essential for the refinement of existing mathematical models that simulate the spread of influenza in the human population and model the deployment of antiviral agents. These models are designed to assess the likely impact of different antiviral agent deployment strategies to control pandemic influenza (18, 21, 35). At present, data on the probability of emergence of NAI-resistant strains, the relative transmission fitness of these strains, and the probability of an individual''s infection reverting to an NAI-sensitive strain in the absence of ongoing selective pressure are severely limited. In consequence, human population-level models of influenza spread must make gross assumptions on the likely characteristics of NAI-resistant strains. Data such as those presented here will be used to inform new models of drug deployment and result in improved pandemic policy advice (20, 23).     

Assessing the Risk of Soil Pollution around an Industrialized Mining Region Using a Geostatistical Approach

Knowledge of mobility of some heavy metals in coal mining areas is fundamental in order to understand their toxicity and geochemical behavior. This paper aims to map pollution and assess the risk to agricultural soils in a wider lignite opencast mining and industrial area. Geochemical data related to environmental studies show that the waste characteristics favor solubilization and mobilization of inorganic contaminants. The geochemical distribution of soil pollution is studied by the application of the Bayesian Maximum Entropy (BME) procedure, a versatile extension of geostatistics which allows merging spatial and temporal estimations in a single model. Results reveal a correlation range of contaminants concentrations up to 5000 m and indicate a potential forecasting range of up to five years. Inspection of the produced spatiotemporal maps indicates that the whole study area is contaminated by As and various heavy metals, a situation which seems to be more or less stable over time.     

Coflex植入术与Quadrant通道下TLIF结合经皮Sextant椎弓根螺钉治疗退行性腰椎管狭窄症的疗效对比

目的:对比棘突间动态稳定装置Coflex系统植入与Quadrant通道结合经皮Sextant椎弓根螺钉内固定术治疗退行性腰椎管狭窄症的短期疗效.方法:抽取兰州军区兰州总医院骨科中心脊柱外科及第四军医大学唐都骨科医院脊柱外科的30例住院治疗退行性腰椎管狭窄症的患者,随机化分为2组,每组15例,分别行Coflex系统植入和Quadrant通道结合经皮Sextant椎弓根螺钉内固定术,观察比较两组的手术时间、出血量、术后住院时间、术前和术后6个月Oswestry功能障碍指数(Oswestry disability index,简称ODI)及视觉模拟评分法(Visual Analogue Scale/Score,简称VAS).结果:两组术前、术后6个月ODI及VAS评分对比差异有统计学意义,而在手术时间、术中出血量及术后住院天数方面Coflex组优于Quadrant+Sextant组,两组在术后6个月ODI评分方面差异无统计学意义,在术后6个月VAS评分方面Quadrant+Sextant组优于Coflex组,随访期间两组无并发症发生.结论:Coflex植入术及Quadrant通道结合经皮Sextant椎弓根螺钉内固定术均为治疗退行性腰椎管狭窄症的有效手段,但其各有特点,在临床工作中,应当严格掌握手术适应症,选择适当的手术方案,从而在最小的创伤和侵扰的同时获得最佳的疗效.     

Assessing the Innate Sensing of HIV-1 Infected CD4+ T Cells by Plasmacytoid Dendritic Cells Using an Ex vivo Co-culture System.

HIV-1 innate sensing requires direct contact of infected CD4⁺ T cells with plasmacytoid dendritic cells (pDCs). In order to study this process, the protocols described here use freshly isolated human peripheral blood mononuclear cells (PBMCs) or plasmacytoid dendritic cells (pDCs) to sense infections in either T cell line (MT4) or heterologous primary CD4⁺ T cells. In order to ensure proper sensing, it is essential that PBMC are isolated immediately after blood collection and that optimal percentage of infected T cells are used. Furthermore, multi-parametric flow cytometric staining can be used to confirm that PBMC samples contain the different cell lineages at physiological ratios. A number of controls can also be included to evaluate viability and functionality of pDCs. These include, the presence of specific surface markers, assessing cellular responses to known agonist of Toll-Like Receptors (TLR) pathways, and confirming a lack of spontaneous type-I interferon (IFN) production. In this system, freshly isolated PBMCs or pDCs are co-cultured with HIV-1 infected cells in 96 well plates for 18-22 hr. Supernatants from these co-cultures are then used to determine the levels of bioactive type-I IFNs by monitoring the activation of the ISGF3 pathway in HEK-Blue IFN-α/β cells. Prior and during co-culture conditions, target cells can be subjected to flow cytometric analysis to determine a number of parameters, including the percentage of infected cells, levels of specific surface markers, and differential killing of infected cells. Although, these protocols were initially developed to follow type-I IFN production, they could potentially be used to study other imuno-modulatory molecules released from pDCs and to gain further insight into the molecular mechanisms governing HIV-1 innate sensing.