Gender and Age-Related Differences in Bilateral Lower Extremity Mechanics during Treadmill Running

Female runners have a two-fold risk of sustaining certain running-related injuries as compared to their male counterparts. Thus, a comprehensive understanding of the sex-related differences in running kinematics is necessary. However, previous studies have either used discrete time point variables and inferential statistics and/or relatively small subject numbers. Therefore, the first purpose of this study was to use a principal component analysis (PCA) method along with a support vector machine (SVM) classifier to examine the differences in running gait kinematics between female and male runners across a large sample of the running population as well as between two age-specific sub-groups. Bilateral 3-dimensional lower extremity gait kinematic data were collected during treadmill running. Data were analysed on the complete sample (n = 483: female 263, male 220), a younger subject group (n = 56), and an older subject group (n = 51). The PC scores were first sorted by the percentage of variance explained and we also employed a novel approach wherein PCs were sorted based on between-gender statistical effect sizes. An SVM was used to determine if the sex and age conditions were separable and classifiable based on the PCA. Forty PCs explained 84.74% of the variance in the data and an SVM classification accuracy of 86.34% was found between female and male runners. Classification accuracies between genders for younger subjects were higher than a subgroup of older runners. The observed interactions between age and gender suggest these factors must be considered together when trying to create homogenous sub-groups for research purposes.     

Heart Rate Differences between Targets and Nontargets in Intuitive Tasks

This study reports the results of one experiment and a replication, aimed at investigating heart rate changes related to a purely intuitive task. In each experiment, 12 subjects were required to guess which of four pictures presented in sequence for about 10 s was the target. Each subject performed 20 trials. In each trial, the target was automatically selected using a pseudorandom algorithm. The heart rate was recorded during the picture presentation. In the first experiment, a statistically significant heart rate increment associated with targets with respect to nontargets was observed. The replication experiment with 12 new subjects confirmed the data obtained in the main experiment. These findings support the hypothesis that heart rate is related not only to conscious but also to unconscious cognitive activity such as that involved in intuitive tasks, giving convergent evidence for the models describing human intuitive cognitive activity as a double, partially independent information processing system.     

Effect of the Fatigue Induced by a 110-km Ultramarathon on Tibial Impact Acceleration and Lower Leg Kinematics

Ultramarathon runners are exposed to a high number of impact shocks and to severe neuromuscular fatigue. Runners may manage mechanical stress and muscle fatigue by changing their running kinematics. Our purposes were to study (i) the effects of a 110-km mountain ultramarathon (MUM) on tibial shock acceleration and lower limb kinematics, and (ii) whether kinematic changes are modulated according to the severity of neuromuscular fatigue. Twenty-three runners participated in the study. Pre- and post-MUM, neuromuscular tests were performed to assess knee extensor (KE) and plantar flexor (PF) central and peripheral fatigue, and a treadmill running bouts was completed during which step frequency, peak acceleration, median frequency and impact frequency content were measured from tibial acceleration, as well as foot-to-treadmill, tibia-to-treadmill, and ankle flexion angles at initial contact, and ankle range of motion using video analysis. Large neuromuscular fatigue, including peripheral changes and deficits in voluntary activation, was observed in KE and PF. MVC decrements of ~35% for KE and of ~28% for PF were noted. Among biomechanical variables, step frequency increased by ~2.7% and the ankle range of motion decreased by ~4.1% post-MUM. Runners adopting a non rearfoot strike pre-MUM adopted a less plantarflexed foot strike pattern post-MUM while those adopting a rearfoot strike pre-MUM tended to adopt a less dorsiflexed foot strike pattern post-MUM. Positive correlations were observed between percent changes in peripheral PF fatigue and the ankle range of motion. Peripheral PF fatigue was also significantly correlated to both percent changes in step frequency and the ankle angle at contact. This study suggests that in a fatigued state, ultratrail runners use compensatory/protective adjustments leading to a flatter foot landing and this is done in a fatigue dose-dependent manner. This strategy may aim at minimizing the overall load applied to the musculoskeletal system, including impact shock and muscle stretch.     

The Differences in Lower Extremity Joints Energy Dissipation Strategy during Landing between Athletes with Symptomatic Patellar Tendinopathy (PT) and without Patellar Tendinopathy (UPT)

Patellar tendinopathy is a clinical symptom of patellar tendons characterized by local pain in the front of the knee joint. It is common among basketball and volleyball players. Patients with patellar tendinopathy may exhibit different landing strategies during landing compared to healthy individuals. The purpose of this study was to compare the differences in lower limb joint energy dissipation (eccentric work) values for the symptomatic patellar tendinopathy (PT) athletes and no patellar tendinopathy (UPT) athletes during single-leg landing. A total of 26 (PT: 13, UPT:13) semi-professional male basketball and volleyball player’s kinetic data were collected during the landing phases. Joint work was calculated by the integral of joint power over time. In this study, the result showed that the ankle joint means energy dissipation (p < 0.001) and total energy dissipation (p < 0.001) of PT were significantly greater than UPT. Compared to the UPT athletes, the PT athletes showed smaller knee joint mean energy dissipation (p = 0.002) and contribution to total energy dissipation (p < 0.001) during the landing stance. Meanwhile, there were no differences in hip joint contribution to total energy dissipation (p = 0.523) and lower limb total energy dissipation (p = 0.127). A deeper understanding of each joint’s energy dissipation contribution ratio between UPT and PT during landing can provide clues that reveal the biomechanical mechanism of PT athletes landing. Further study should choose a larger sample size to more comprehensively reveal the energy dissipation strategy of PT during landing.     

Timing of Muscle Response to a Sudden Leg Perturbation: Comparison between Adolescents and Adults with Down Syndrome

Movement disturbances associated with Down syndrome reduce mechanical stability, worsening the execution of important tasks such as walking and upright standing. To compensate these deficits, persons with Down syndrome increase joint stability modulating the level of activation of single muscles or producing an agonist-antagonist co-activation. Such activations are also observed when a relaxed, extended leg is suddenly released and left to oscillate passively under the influence of gravity (Wartenberg test). In this case, the Rectus femoris of adults with Down syndrome displayed peaks of activation after the onset of the first leg flexion. With the aim to verify if these muscular reactions were acquired during the development time and to find evidences useful to give them a functional explanation, we used the Wartenberg test to compare the knee joint kinematics and the surface electromyography of the Rectus femoris and Biceps femoris caput longus between adolescents and adults with Down syndrome. During the first leg flexion, adolescents and adults showed single Rectus femoris activations while, a restricted number of participants exhibited agonist-antagonist co-activations. However, regardless the pattern of activation, adults initiated the muscle activity significantly later than adolescents. Although most of the mechanical parameters and the total movement variability were similar in the two groups, the onset of the Rectus femoris activation was well correlated with the time of the minimum acceleration variability. Thus, in adolescents the maximum mechanical stability occurred short after the onset of the leg fall, while adults reached their best joint stability late during the first flexion. These results suggest that between the adolescence and adulthood, persons with Down syndrome explore a temporal window to select an appropriate timing of muscle activation to overcome their inherent mechanical instability.     

2型糖尿病患者肝损伤标志物与下肢动脉病变的相关性分析

目的：探讨2型糖尿病患者肝损伤标志物水平与其下肢动脉病变的相关性,为2型糖尿病并发症的防治提供参考依据。方法：选取我院收治的2型糖尿病患者946例,根据下肢动脉内膜中层厚度分为以下3组,即无动脉硬化组（276例）、单纯性动脉硬化组（598例）和动脉硬化伴管腔狭窄或闭塞组（72例）。分析和比较三组之间肝损伤标志物谷丙转氨酶（ALT）、谷草转氨酶（AST）、γ-谷氨酰转肽酶（GGT）水平的差异,及其与2型糖尿病患者下肢动脉硬化程度的相关性。结果：随着动脉硬化程度的加重,2型糖尿病患者的ALT水平逐渐升高,三组之间两两比较差异均有统计学意义（P〈0．05）。动脉硬化伴管腔狭窄或闭塞组AST水平显著高于非动脉硬化组和单纯性下肢动脉硬化组,而动脉硬化组和非动脉硬化组之间AsT水平比较无显著差异（P〉0．05）。三组之间γ-谷氨酰转肽酶水平比较无显著性差异（P〉0．05）。Spearman等级相关分析显示ALT与糖尿病下肢动脉硬化的相关系数为0．30484。结论：2型糖尿病患者ALT水平与其下肢动脉硬化程度显著相关。     

2 型糖尿病患者肝损伤标志物与下肢动脉病变的相关性分析

目的：探讨2 型糖尿病患者肝损伤标志物水平与其下肢动脉病变的相关性,为2 型糖尿病并发症的防治提供参考依据。方 法：选取我院收治的2 型糖尿病患者946 例,根据下肢动脉内膜中层厚度分为以下3 组,即无动脉硬化组(276 例)、单纯性动脉硬 化组(598 例)和动脉硬化伴管腔狭窄或闭塞组(72 例)。分析和比较三组之间肝损伤标志物谷丙转氨酶(ALT)、谷草转氨酶(AST)、γ-谷氨酰转肽酶(GGT)水平的差异,及其与2型糖尿病患者下肢动脉硬化程度的相关性。结果：随着动脉硬化程度的加重,2 型糖尿病患者的ALT 水平逐渐升高,三组之间两两比较差异均有统计学意义(P<0.05)。动脉硬化伴管腔狭窄或闭塞组AST 水平显著高于非动脉硬化组和单纯性下肢动脉硬化组,而动脉硬化组和非动脉硬化组之间AST 水平比较无显著差异(P>0.05)。三组之间γ-谷氨酰转肽酶水平比较无显著性差异(P>0.05)。Spearman 等级相关分析显示ALT 与糖尿病下肢动脉硬化的相关系数为0.30484。结论：2型糖尿病患者ALT 水平与其下肢动脉硬化程度显著相关。     

Effect of Trunk Sagittal Attitude on Shoulder,Thorax and Pelvis Three-Dimensional Kinematics in Able-Bodied Subjects during Gait

It has been shown that an original attitude in forward or backward inclination of the trunk is maintained at gait initiation and during locomotion, and that this affects lower limb loading patterns. However, no studies have shown the extent to which shoulder, thorax and pelvis three-dimensional kinematics are modified during gait due to this sagittal inclination attitude. Thirty young healthy volunteers were analyzed during level walking with video-based motion analysis. Reflecting markers were mounted on anatomical landmarks to form a two-marker shoulder line segment, and a four-marker thorax and pelvis segments. Absolute and relative spatial rotations were calculated, for a total of 11 degrees of freedom. The subjects were divided into two groups of 15 according to the median of mean thorax inclination angle over the gait cycle. Preliminary MANOVA analysis assessed whether gender was an independent variable. Then two-factor nested ANOVA was used to test the possible effect of thorax inclination on body segments, planes of motion and gait periods, separately. There was no significant difference in all anthropometric and spatio-temporal parameters between the two groups, except for subject mass. The three-dimensional kinematics of the thorax and pelvis were not affected by gender. Nested ANOVA revealed group effect in all segment rotations apart those at the pelvis, in the sagittal and frontal planes, and at the push-off. Attitudes in sagittal thorax inclination altered trunk segments kinematics during gait. Subjects with a backward thorax showed less thorax-to-pelvis motion, but more shoulder-to-thorax and thorax-to-laboratory motion, less motion in flexion/extension and in lateral bending, and also less motion during push-off. This contributes to the understanding of forward propulsion and sideways load transfer mechanisms, fundamental for the maintenance of balance and the risk of falling.     

D-二聚体、P-选择素及血管内皮生长因子与下肢骨折患者深静脉血栓形成的关系

摘要 目的：探究D-二聚体(D-D)、P-选择素及血管内皮生长因子(VEGF)与下肢骨折患者深静脉血栓(DVT)形成的关系。方法：选取2017年2月至2019年10月期间我院诊治的80例下肢骨折并发DVT患者作为DVT组,选择同期治疗的95例下肢骨折但未并发DVT患者作为无DVT组。比较两组患者的各项临床资料,采用多因素Logistic回归分析下肢骨折患者DVT发生的危险因素,采用受试者工作特征（ROC）曲线分析血清D-D、P-选择素、VEGF对下肢骨折患者DVT的诊断价值。结果：与无DVT组相比,DVT组血清D-D、P-选择素和VEGF水平明显升高（P<0.05）。多因素Logistic回归分析结果显示血清D-D、P-选择素、VEGF是下肢骨折患者DVT发生的危险因素（OR=1.996、2.335、1.743,P<0.05）。ROC曲线分析结果显示血清D-D、P-选择素、VEGF诊断下肢骨折患者DVT的曲线下面积（AUC）分别为0.771、0.790、0.812,血清D-D、P-选择素、VEGF联合诊断下肢骨折患者DVT的AUC为0.945。结论：下肢骨折合并DVT患者血清D-D、P-选择素、VEGF水平明显升高,并且血清D-D、P-选择素和VEGF是下肢骨折患者发生DVT的危险因素,三者联合检测在下肢骨折患者发生DVT的诊断和预测中具有一定临床意义。     

阿加曲班与葛根素联合治疗糖尿病下肢动脉硬化闭塞症的临床研究

目的:研究阿加曲班与葛根素联合治疗糖尿病动脉硬化闭塞症的临床效果。方法:选择糖尿病动脉硬化闭塞症患者124例。随机分为观察组与对照组,各62例。观察组给予阿加曲班与葛根素联合治疗,对照组单用阿加曲班治疗。治疗前使用降糖和降压药物使血糖和血压保持稳定。观察治疗前后临床症状改善的情况,检测治疗前后足背动脉血流量及踝/肱动脉压比值。结果:单用阿加曲班组及联合葛根素组在改善糖尿病动脉硬化闭塞症的临床症状方面均有良好的效果,但联合葛根素组比单用阿加曲班组的治疗效果更佳(P<0.01)。在足背动脉血流量,踝/肱动脉压比值治疗前后各项指标的改善方面,联合葛根素组比单用阿加曲班组的治疗效果更佳,差异亦有统计学意义(均为P<0.05)。两组治疗期间和治疗后均无明显不良反应,耐受性好。结论:糖尿病动脉硬化闭塞症患者经使用阿加曲班与葛根素联合治疗,效果良好,二者具有协同作用。     

2型糖尿病患者血糖波动与心律失常和下肢血管病变的关系及其影响因素分析

目的:探讨2型糖尿病(T2DM)患者血糖波动与心律失常和下肢血管病变的关系,分析影响T2DM心律失常和下肢血管病变的因素.方法:选择2019年7月到2020年6月我院收治的82例T2DM患者,根据是否合并心律失常分为心律失常组28例和无心律失常组54例,根据是否合并下肢血管病变分为下肢血管病变组31例和无下肢血管病变组...     

Differences in maternal age-specific rates of Down syndrome between Jews of European origin and of North African or Asian origin.

Rates of Down syndrome in livebirths in West Jerusalem in 1964-1975 were studied in relation to the mother's continent of birth or, if she was born in Israel, to the maternal grandfather's continent of birth. In women of European origin the crude livebirth rate of Down syndrome was 1.3 per 1,000 livebirths. This crude rate and the maternal age-specific rates in this group were very close to those observed in a Swedish study and two studies of white livebirths in the United States. For West Jerusalem women of North African or Asian origin the crude rate was about 2.4 per 1,000 livebirths, and at all maternal ages except the youngest their rates were higher than for women of European origin. The summary adjusted relative risk for a Down syndrome livebirth for all those of North African or Asian origin, compared to those for women of European origin, was about 1.56. If attention is restricted to mothers born outside of Israel, the adjusted relative risk for mothers born in Europe, the Americas or English speaking countries of the British commonwealth compared to those born in North Africa or Asia was 1.97, consistent with a two-fold difference in the likelihood of a Down syndrome livebirth between thes two groups. To our knowledge this is the first report of ethnic differences in maternal age specific rates of Down syndrome that cannot be plausibly explained by differences in ascertainment.     

Mapping of Single-Base Differences between Two DNA Strands in a Single Molecule Using Holliday Junction Nanomechanics

Objective

The aim of this work is to demonstrate a novel single-molecule DNA sequence comparison assay that is purely based on DNA mechanics.

Methods

A molecular construct that contained the two homologous but non-identical DNA sequences that were to be compared was prepared such that a four-way (Holliday) junction could be formed by the formation of heteroduplexes through the inter-recombination of the strands. Magnetic tweezers were used to manipulate the force and the winding applied to this construct for inducing both the formation and the migration of a Holliday junction. The end-to-end distance of the construct was measured as a function of the winding and was used to monitor the behavior of the Holliday junction in different regions of the intra-molecular recombination.

Main Results

In the appropriate buffer, the magnet rotation induces the migration of the Holliday junction in the regions where there is no sequence difference between the recombining sequences. In contrast, even a single-base difference between the recombining sequences leads to a long-lasting blockage of the migration in the same buffer; this effect was obtained when the junction was positioned near this locus (the site of the single-base difference) and forced toward the formation of heteroduplexes that comprise the locus. The migration blockages were detected through the identification of the formation of plectonemes. The detection of the presence of sequence differences and their respective mappings were obtained from the series of blockages that were detected.

Significance

This work presents a novel single-molecule sequence comparison assay that is based on the use of a Holliday junction as an ultra-sensitive nanomechanism; the mismatches act as blocking grains of sand in the Holliday “DNA gearbox”. This approach will potentially have future applications in biotechnology.     

Differences in the Relationship of Menstrual Cycle Phase to Spatial Performance on Two- and Three-Dimensional Tasks

Inverse activational effects of estrogen on spatial problem-solving performance in females have been amply demonstrated, although the findings across studies are somewhat inconsistent. In an attempt to resolve this ambiguity, the present study compared activational effects, using phases of the menstrual cycle as the criteria for estrogen levels, on two- and three-dimensional spatial tasks. As predicted, menstrual cycle effects were obtained for the latter category only. Results were interpreted as a function of the greater ecological validity of three-dimensional tasks.     

Rhythmic Differences in the Basipetal Movement of Indoleacetic Acid between Separated Upper and Lower Halves of Geotropically Stimulated Corn Coleoptiles

Rhythmic fluctuation in the basipetal movement of auxin occurs in corn (Zea mays) coleoptiles oriented either in the vertical or in the horizontal position. This periodicity of transport rate varies from region to region in a horizontal coleoptile. Between an upper and lower half coleoptile (with respect to gravity), the comparable regions in the coleoptile do not exhibit similar periods. The velocity of transport also varies from region to region along a geostimulated coleoptile. In the upper half coleoptile, the velocities are 29 millimeters per hour (tip), 8 millimeters per hour (mid), and 30 millimeters per hour (base); in the lower, 41 millimeters per hour (tip), 12 millimeters per hour (mid) and 12 millimeters per hour (base).     

64排螺旋CTA在下肢动脉闭塞及狭窄性病变中应用价值

目的：评价64排螺旋CT血管造影在下肢动脉闭塞性及狭窄性病变中应用价值。方法：采用美国GE公司生产LightSpeed VCT对52例患者进行下肢血管造影检查。扫描层厚0．625mm,管电压120KV、管电流130．205mAs,扫描时间约为10秒。图像后处理技术多采用VR、M1P、MPR、cMPR,图像分析密切结合原始轴位图像。结果：67支血管未见明确病变,CTA显示狭窄血管共77支,5支血管闭塞;狭窄≥50％,≤75％共21支;狭窄≤50％共51支。结论：64排CTA图像在发现闭塞远端血管方面优于DSA,可以清晰显示闭塞远端侧枝供血血管。随着64排螺旋CT临床广泛应用,在下肢血管疾病诊断方面的优势会得到长足发展。     

64 排螺旋CTA 在下肢动脉闭塞及狭窄性病变中应用价值

目的:评价64排螺旋CT血管造影在下肢动脉闭塞性及狭窄性病变中应用价值。方法:采用美国GE公司生产LightSpeedVCT对52例患者进行下肢血管造影检查。扫描层厚0.625 mm,管电压120 KV、管电流130-205 mAs,扫描时间约为10秒。图像后处理技术多采用VR、MIP、MPR、cMPR,图像分析密切结合原始轴位图像。结果:67支血管未见明确病变,CTA显示狭窄血管共77支,5支血管闭塞;狭窄≥50%,≤75%共21支;狭窄≤50%共51支。结论:64排CTA图像在发现闭塞远端血管方面优于DSA,可以清晰显示闭塞远端侧枝供血血管。随着64排螺旋CT临床广泛应用,在下肢血管疾病诊断方面的优势会得到长足发展。