兰索拉唑联合莫沙必利对胃食管反流患者的胃食管动力学及胃电活动指标的影响

目的分析兰索拉唑联合莫沙必利对胃食管反流患者的胃食管动力学及胃电活动指标的影响。方法选取2010年1月-2012年1月收治的136例胃食管反流患者为研究对象,将患者随机分为对照组和观察组各68例,对照组给予兰索拉唑治疗,观察组在对照组基础上加用莫沙必利。将两组患者治疗前与治疗后2周、4周、12周的胃食管动力学指标及胃电参数进行比较。结果观察组治疗后2周、4周、12周的胃食管动力学指标及胃电参数均明显优于对照组,且观察组治疗后胃食管动力学指标及胃电参数呈进行性升高(P0.05)。结论兰索拉唑联合莫沙必利对胃食管反流患者的胃食管动力学及胃电活动指标的影响较大,治疗效果较好。     

Thermotolerant mycobiota of Israeli soils

Composition of thermotolerant mycobiota in the soil of Israeli deserts and northern territories was examined in spatiotemporal dynamics. A total of 165 species from 82 genera were isolated at 37 °C using the soil dilution plate method. Aspergilli (Aspergillus fumigatus and A. niger) and teleomorphic ascomycetes (Canariomyces notabilis, Chaetomium nigricolor, and Ch. strumarium) comprised the basic part of the thermotolerant communities. The desert communities remarkably differed from the northern communities by a much higher abundance of A. fumigatus and teleomorphic species, as well as by a lower abundance of A. niger and Rhizopus arrhyzus. Seasonal dynamics revealed for the southern Negev was expressed mainly in the variations of species richness (substantially lower in the winter), and abundances of A. fumigatus (dominant in the summer) and A. niger (dominant in the winter). The composition of thermotolerant mycobiota was almost entirely different from the composition of mesophilic mycobiota at 25 °C. Melanin‐containing fungi with many‐celled conidia that dominated mesophilic communities in the deserts did not grow at 37 °C, while prevailing aspergilli accompanied by teleomorphic species with perithecial fruit bodies were apparently able not only to survive but also to germinate at this temperature and be active during a long hot period in the desert.     

Dynamic instability during post-stroke hemiparetic walking

Falls and fall-related injuries cause extremely costly and potentially fatal health problems in people post-stroke. However, there is no global indicator of walking instability for detecting which individuals will have increased risk of falls. The purposes of this study were to directly quantify walking stability in stroke survivors and neurologically intact controls and to determine which stability measures would reveal the changes in walking stability following stroke. This study thus provided an initial step to establish objective measures for identifying potential fallers. Nine post-stroke individuals and nine controls walked on a treadmill at four different speeds. We computed short-term local divergence exponent (LDE) and maximum Floquet multiplier (maxFM) of the trunk motion, average and variability of dynamic margins of stability (MOS) and step spatiotemporal measures. Post-stroke individuals demonstrated larger short-term LDE (p = 0.002) and maxFM (p = 0.041) in the mediolateral (ML) direction compared to the controls but remained orbitally stable (maxFM < 1). In addition, post-stroke individuals walked with greater average step width (p = 0.003) but similar average ML MOS (p = 0.154) compared to the controls. Post-stroke individuals also exhibited greater variability in all MOS and step measures (all p < 0.005). Our findings indicate that post-stroke individuals walked with greater local and orbital instability and gait variability than neurologically intact controls. The results suggest that short-term LDE of ML trunk motion and the variability of MOS and step spatiotemporal measures detect the changes in walking stability associated with stroke. These stability measures may have the potential for identifying those post-stroke individuals at increased risk of falls.     

两种无创正压机械通气模式在COPD急性加重期患者中的应用价值比较

目的比较两种无创正压机械通气模式在慢性阻塞性肺疾病急性加重期 (AECOPD)患者中的应用价值。方法将 98 例 AECOPD 患者随机分为研究组和对照组,各 49 例,分别行压力调节容量控制通气(PRVC)和双水平正压通气(Bi PAP)。记录人均每日带机时间(TA)、总人均带机时间(TB)及平均漏气量(Lleak),于通气前(T1)、通气 1h(T2)、6h(T3)、1d(T4)、3d (T5)、7d(T6)时检测患者动脉血气指标[p H、氧合指数(PaO_2/FiO_2)、动脉血二氧化碳分压(PaCO_2)],观察两组 T1 及 T6 时呼吸动力学指标[自主呼吸潮气量 (VT)、每分钟通气量 (VE)、呼吸频率(RR)、浅速呼吸指数(f/VT)、呼吸功(WORKP)]差异,记录气管插管率和并发症发生情况。结果研究组 TB、TA 均大于对照组 ,Lleak 则小于对照组 (P 均0.05)。 T1~T6 时 ,两组 pH、PaO_2/FiO_2均逐渐升高,PaCO_2则逐渐降低,但各时间上述指标组间比较,差异均无统计学意义(P 均0.05)。T6 时,两组 VT、VE 均较 T1 时上升,RR、f/VT、WORKP 则均较 T1 时降低 ,且研究组变化幅度大于对照组 (P 均0.05)。两组气管插管率和并发症发生率比较 ,差异均无统计学意义(P 均0.05)。结论 PRVC 和 BiPAP 在 AECOPD 治疗过程中均可有效改善血气指标,PRVC可显著提高人机协同性、改善氧合功能、减少呼吸肌做功、减少漏气,于 AECOPD 患者病情改善有利。     

Simulation of dental collisions and occlusal dynamics in the virtual environment

Semi‐adjustable articulators have often been used to simulate occlusal dynamics, but advances in intra‐oral scanning and computer software now enable dynamics to be modelled mathematically. Computer simulation of occlusal dynamics requires accurate virtual casts, records to register them and methods to handle mesh collisions during movement. Here, physical casts in a semi‐adjustable articulator were scanned with a conventional clinical intra‐oral scanner. A coordinate measuring machine was used to index their positions in intercuspation, protrusion, right and left laterotrusion, and to model features of the articulator. Penetrations between the indexed meshes were identified and resolved using restitution forces, and the final registrations were verified by distance measurements between dental landmarks at multiple sites. These sites were confirmed as closely approximating via measure‐ments made from homologous transilluminated vinylpolysiloxane interocclusal impressions in the mounted casts. Movements between the indexed positions were simulated with two models in a custom biomechanical software platform. In model DENTAL, 6 degree‐of‐freedom movements were made to minimise deviation from a straight line path and also shaped by dynamic mesh collisions detected and resolved mathematically. In model ARTIC, the paths were further constrained by surfaces matching the control settings of the articulator. Despite these differences, the lower mid‐incisor point paths were very similar in both models. The study suggests that mathematical simulation utilising interocclusal ‘bite’ registrations can closely replicate the primary movements of casts mounted in a semi‐adjustable articulator. Additional indexing positions and appropriate software could, in some situations, replace the need for mechanical semi‐adjustable articulation and/or its virtual representation.     

Comparison of invasively measured FFR with FFR derived from coronary CT angiography for detection of lesion-specific ischemia: Results from a PC-based prototype algorithm

BackgroundWe evaluated the diagnostic accuracy of a novel prototype for on-site determination of CT-based FFR (cFFR) on a standard personal computer (PC) compared to invasively measured FFR in patients with suspected coronary artery disease.MethodsA total of 91 vessels in 71 patients (mean age 65 ± 9 years) in whom coronary CT angiography had been performed due to suspicion of coronary artery disease, and who subsequently underwent invasive coronary angiography with FFR measurement were analyzed. For both cFFR and FFR, a threshold of ≤0.80 was used to indicate a hemodynamically relevant stenosis. The mean time needed to calculate cFFR was 12.4 ± 3.4 min. A very close correlation between cFFR and FFR could be shown (r = 0.85; p < 0.0001) with Bland-Altman analysis showing moderate agreement between FFR and cFFR with mild systematic overestimation of FFR values in CT (mean difference 0.0049, 95% limits of agreement ±2SD −0.007 to 0.008). Compared to FFR, the sensitivity of cFFR to detect hemodynamically significant lesions was 91% (19/21, 95% CI: 70%–99%), specificity was 96% (67/70, 95% CI: 88%–99%), positive predictive value 86% (95% CI: 65%–97%) and negative predictive value was 97% (95% CI: 90%–100%) with an accuracy of 93%.ConclusioncFFR obtained using an on-site algorithm implemented on a standard PC shows high diagnostic accuracy to detect lesions causing ischemia as compared to FFR. Importantly, the time needed for analysis is short which may be useful for improving clinical workflow.     

From the Cover: Strain history dependence of the nonlinear stress response of fibrin and collagen networks

We show that the nonlinear mechanical response of networks formed from un–cross-linked fibrin or collagen type I continually changes in response to repeated large-strain loading. We demonstrate that this dynamic evolution of the mechanical response arises from a shift of a characteristic nonlinear stress–strain relationship to higher strains. Therefore, the imposed loading does not weaken the underlying matrices but instead delays the occurrence of the strain stiffening. Using confocal microscopy, we present direct evidence that this behavior results from persistent lengthening of individual fibers caused by an interplay between fiber stretching and fiber buckling when the networks are repeatedly strained. Moreover, we show that covalent cross-linking of fibrin or collagen inhibits the shift of the nonlinear material response, suggesting that the molecular origin of individual fiber lengthening may be slip of monomers within the fibers. Thus, a fibrous architecture in combination with constituents that exhibit internal plasticity creates a material whose mechanical response adapts to external loading conditions. This design principle may be useful to engineer novel materials with this capability.     

Simulation of 125I-based radioprobing experiments to study DNA quadruplex structure and topology

Purpose: Certain guanine-rich DNA sequences have the capacity to fold into four-stranded structures stabilized by the stacking of square planar arrangements of four hydrogen-bonded guanine bases. However both the overall topology of folding and the more detailed three dimensional structure of these quadruplexes is difficult to determine or predict, and they can be polymorphic, altering radically depending on environmental conditions. Radioprobing experiments, in which Auger electrons emitted during the decay of a ¹²⁵I-containing base induce strand cleavage in a distance- and structure-dependent manner, have provided possible means of determining these details. Here we have used a combination of computer simulation methods to study the information obtained by one such experiment, reported in 2004.

Method: Models were constructed of three quadruplex topologies considered in the experiment, and one other topology proposed more recently. Molecular Dynamics simulations were used to equilibrate these structures and monitor how they evolved over several nanoseconds in solution. Snapshots from the trajectories were then subjected to Monte Carlo track structure prediction, from which theoretical cleavage patterns have been extracted.

Results: The four topologies were found to yield quite different cleavage patterns, which allow the presence of particular conformations in an experiment to be predicted.

Conclusion: Radioprobing, which is usable in biologically relevant environments, is sensitive enough to distinguish with some confidence between alternative folding topologies in a DNA structure. Monte Carlo track structure simulation can reinforce or question conclusions drawn from experiment, and Molecular Dynamics used with various restraints provides a practical means of guiding a model towards one that yields cleavage patterns closer to those found experimentally.     

Feasibility of Ultrasound-Based Computational Fluid Dynamics as a Mitral Valve Regurgitation Quantification Technique: Comparison with 2-D and 3-D Proximal Isovelocity Surface Area-Based Methods

Current Doppler echocardiography quantification of mitral regurgitation (MR) severity has shortcomings. Proximal isovelocity surface area (PISA)-based methods, for example, are unable to account for the fact that ultrasound Doppler can measure only one velocity component: toward or away from the transducer. In the present study, we used ultrasound-based computational fluid dynamics (Ub-CFD) to quantify mitral regurgitation and study its advantages and disadvantages compared with 2-D and 3-D PISA methods. For Ub-CFD, patient-specific mitral valve geometry and velocity data were obtained from clinical ultrasound followed by 3-D CFD simulations at an assumed flow rate. We then obtained the average ratio of the ultrasound Doppler velocities to CFD velocities in the flow convergence region, and scaled CFD flow rate with this ratio as the final measured flow rate. We evaluated Ub-CFD, 2-D PISA and 3-D PISA with an in vitro flow loop, which featured regurgitation flow through (i) a simplified flat plate with round orifice and (ii) a 3-D printed realistic mitral valve and regurgitation orifice. The Ub-CFD and 3-D PISA methods had higher precision than the 2-D PISA method. Ub-CFD had consistent accuracy under all conditions tested, whereas 2-D PISA had the lowest overall accuracy. In vitro investigations indicated that the accuracy of 2-D and 3-D PISA depended significantly on the choice of aliasing velocity. Evaluation of these techniques was also performed for two clinical cases, and the dependency of PISA on aliasing velocity was similarly observed. Ub-CFD was robustly accurate and precise and has promise for future translation to clinical practice.     

The Obesity Paradox: Body Mass Index Complication Rates Vary by Gender and Age Among Primary Total Hip Arthroplasty Patients

BackgroundHigh body mass index (BMI) has long been recognized as a risk factor for postoperative complication among total hip arthroplasty (THA) patients. However, recent studies showed mixed results in the effect of high BMI on surgical outcomes. Our study is to examine the association of preoperative BMI with complication incidence, stratified by age and gender.MethodsWe queried the American College of Surgeons National Surgical Quality Improvement Project database to identify patients who underwent elective primary THA between 2012 and 2016. We examined the associations between BMI as a continuous and a categorical variable and risk of 30-day postoperative complication, using 2 multiple polynomial logistic regression models. We also created predictive plots to graphically assess the relationship between BMI and complication by gender and age.ResultsIn total, 117,567 eligible patients were included in the analyses. The predictive probability of all-type postoperative complications showed a U-shaped relationship with continuous BMI values (range 10-65 kg/m²). The lowest complication risks occurred in patients with BMI between 35 and 40. Females had higher complication rate than males across all BMI values. This U-shaped relationship was only observed among patients younger than 60 years old, while the associations appear to be inversely linear among patients aged greater than 60 years.ConclusionOur results suggest that the current theory of a linear association between BMI and complication risk may not apply to elective primary THA. Strict BMI cutoffs may not minimize risk, especially among patients over 60 years old. Orthopedic surgeons should factor in patient-specific variables of age and gender when determining acceptable surgical risk given a particular BMI value.