Age and walking speed effects on muscle recruitment in gait termination

During gait termination at normal walking speed, older adults more frequently employ two-step responses, increasing their stopping distance and stopping time more than younger controls. This study investigated ageing effects on lower limb muscle recruitment patterns during stopping at three walking speeds. Twelve young male (26 +/- 3.7 years, range 19-30) and 12 gender-matched older participants (72 +/- 4.3 years, range 65-82) terminated walking at normal, medium and maximum speed. A visual stopping stimulus was presented 10 ms following either left or right heel-contact with no stimulus (catch) on 30% of trials. Electromyographic (EMG) activity was recorded from the tibialis anterior (TA), soleus (SOL), biceps femoris (BF), vastus lateralis (VL) and gluteus medius (GM). Older males more frequently (46% of trials) took two-steps to stop than young males (20%). The stance leg muscles responded significantly faster than the swing leg, and with increased speed, fewer swing limb muscles contributed to stopping. Older males were slower to respond with the stance leg, at 215 ms following the stimulus compared with 176 ms for the younger group. They also recruited fewer swing leg muscles with less frequent activation of the soleus and gluteus medius. Failure to activate muscles would provide less extensor torque to maintain the centre of gravity anterior to the forward base of support. This would decrease the total force opposing horizontal velocity in order to bring the body to rest and, as a consequence, encourage an additional step prior to stopping.     

Adaptations to changing speed,load, and gradient in human walking: Cost of transport,optimal speed,and pendulum

It has been observed that the optimal speed (OPT) of human walking is independent of load on level surfaces because of the unaltered trajectory of the center of mass and consequent conservation of the pendular mechanism. However, the role of the inverted pendulum mechanism that combines speed, load, and gradient during walking remains unknown. In the present study, 10 subjects walked on a treadmill, with and without loading (25% of the body mass), at different speeds and slopes (0%, +7%, and +15%). The three‐dimensional motion and VO₂ were simultaneously registered. The mechanical external and internal work and the cost of transport (C) changed with the speed and gradient, but the load only affected C. OPT decreased with increasing gradient, and the pendular mechanics (R) was modified mainly as a result of changes in speed and gradient. OPT and R were independent of the load in these gradients. Remarkably, R increased with increasing speed and decreased (to 30%) with an increasing gradient; moreover, R was independent of load. Therefore, the energy‐saving strategy by the pendular mechanism persists, although at a diminished level, in loaded walking on gradients and partially explains the OPT in this condition.     

STRs, mini STRs and SNPs--a comparative study for typing degraded DNA

Short tandem repeat (STR) systems are the most powerful and widely used genetic marker systems in forensic DNA typing. Optimized amplification conditions and PCR reagents in combination with laser fluorescence based detection methods have increased the sensitivity and decreased the detection threshold down to approximately 100 pg. The quality of human DNA from forensic samples can be influenced by environmental factors. These may cause different degrees of degradation which have a negative impact on the amplification process especially of STR systems with large amplicons. Therefore, methods which need only small amplicon sizes to detect DNA markers are a better choice for typing degraded DNA. Here we report investigations on different types of DNA markers and typing methods which should all be applicable for analysing degraded DNA. These are two commercially available mini STR kits and five SNP markers which were analysed with two self established assays, a 5' nuclease assay and a minisequencing (SNaPshot) assay. The investigations comprised sensitivity studies, different types of stain material, as well as intact and degraded DNA. Results indicate that mini STRs are superior to standard STR typing methods, especially for typing old stain material with small amounts of degraded DNA. SNP typing based on the minisequencing (SNaPshot) assay achieved a better success rate in typing aged blood and saliva stains compared to standard STRs and SNP typing using the 5' nuclease assay.     

调节优化训练在弱视治疗中的应用

目的:探讨调节优化训练在弱视治疗中的临床应用。方法:治疗组:58例(110眼),4-12岁,散光在2.00D以下,屈光不正性弱视或屈光参差性弱视,调节优化训练。(极限调节 眼内外肌协调);对照组:49例(92眼),条件与治疗组同,做传统弱视训练。结果:调节优化训练组总有效率94.5%,传统治疗组总有效率46.1,两组比较有显著性差别(P<0.01);按轻中重弱视分类,两种治疗方法比较有显著性差别(P<0.01)。结论:通过优化调节训练,可以提高弱视治疗的效果,缩短弱视治疗的时间。     

Assessment of DNA degradation and the genotyping success of highly degraded samples

DNA becomes progressively more fragmented as biological tissue degrades resulting in decreasing ability to gain a complete DNA profile. Successful identification of samples exhibiting very high levels of DNA degradation may be complicated by presenting in minute quantities. The industry standard method for human DNA identification utilising short tandem repeats (STR) may produce partial or no DNA profile with such samples. We report a comparative study of genotyping using STRs, mini-STRs and single nucleotide polymorphisms (SNPs) with template at different levels of degradation in varying amounts. Two methods of assessing quantity and quality of a DNA sample prior to genotyping were investigated. The QIAxcel capillary gel electrophoresis system provided a rapid, cost effective screening method for assessing sample quality. A real-time quantitative PCR (qPCR) assay was able to simultaneously quantify total human DNA, male DNA, DNA degradation and PCR inhibition. The extent of DNA degradation could be assessed with reasonable accuracy to 62.5 pg and genomic targets could be quantified to a lower limit of 15.6 pg. The qPCR assay was able to detect male DNA to a lower limit of 20 pg in a 1:1,000 background of female DNA. By considering the amount of DNA and the degradation ratio of a sample, a general prediction of genotyping success using AmpFlSTR® Profiler Plus®, MiniFiler? kits and SNP analysis can be made. The results indicate mini-STRs and SNP markers are usually more successful in typing degraded samples and in cases of extreme DNA degradation (≤200 bp) and template amounts below 250 pg, mini-STR and SNP analysis yielded significantly more complete profiles and lower match probabilities than corresponding STR profiles.     

Energy cost of gait in children and the effect of speed,age, and body size

BackgroundEnergy cost (EC) of comfortable walking is often used in clinical evaluation of children with altered gait function. EC is presented as energy expenditure per kg bodyweight per meter, either in total (grossEC) or in addition to resting energy expenditure (netEC). GrossEC is considered more reliable and netEC less affected by between-subject variations in speed, age, and body size. However, the effect of the individual child’s speed on EC is rarely considered, while altered gait function may affect both speed and EC.Research questionTo what extent are grossEC and netEC affected by within-subject variation in speed and between-subject variations in speed, age, and body size?MethodsForty-two typically developing children (7–15 y) were included in this cross-sectional study. Age, height, and bodyweight were obtained. Breath-to-breath gas-exchange measures of VO₂ and VCO₂ were conducted during rest and five over-ground gait conditions: walking at slow, comfortable, and fast speed, jogging and running. All conditions lasted 3–5 min. Body surface area, non-dimensional speed, grossEC, and netEC were calculated. Regression analyses and mixed model analyses were conducted to explain the effect of speed, age, and body size on variations in EC.ResultsGrossEC showed a non-significant, concave up relation to within-subject variation in speed, with a minimum around comfortable/fast walking speed. NetEC had a strong positive linear relation to within-subject variation in speed. For each gait condition, grossEC was more affected by between-subject variations in speed, age, and body size compared to netEC. However, the effect of age and body size was not eliminated for netEC but was quadratic.SignificanceAlthough normalised to speed and bodyweight, grossEC and netEC are still affected by those factors. However, they are affected differently for within- and between-subject variations. This must be considered when interpreting EC in children in relation to gait function.     

Anticipatory locomotor adjustments of the trail limb during surface accommodation

This paper explores anticipatory locomotor adjustments of the trail limb when stepping up to a new level. The kinematics and kinetics of the trail limb for nine subjects were compared across level gait and surface accommodation. The largest generation of new rotational energy was found at the trail ankle, during the latter part of stance (i.e. ankle 'push-off'). Accelerations of the head, arms and trunk (HAT) and foot segments during the same phase indicate that the ankle power acted to push the body and lead limb up onto the new level and drive the foot upwards at toe-off. The shank was more vertical at toe-off to ensure that the ankle energy would drive the limb upwards, rather than forward into the surface. The vertical hip translation energy increased over 300%, acting to pull upwards on the hip to increase trail limb elevation. The increased hip translational energy could be due to extension of the lead limb after it was placed on the surface and/or the piston-like drive of the increased rotational energy at the trail ankle during late stance. The findings add to the knowledge of whole body coordination strategies during anticipatory locomotor adjustments when the entire body is raised to a new level.     

The effect of sex,stature, and limb length on the preferred walk-to-run transition speed

BackgroundThe preferred walk-to-run transition speed (PTS) for healthy adults is approximately 2 m∙s^-1, however, PTS is influenced by anthropometric factors. Yet despite known sex differences in anthropometrics, studies have reported no sex differences in PTS.Research questionDo stature and limb length affect PTS in the same way for both male and female healthy adults?MethodsThirty-seven (19 female) non-injured adults volunteered for this study. Participants completed a walk-to-run transition protocol, where the treadmill speed was increased from 1.2 m∙s^-1 to 2.2 m∙s^-1, in increments of 0.1 m∙s^-1 every two minutes. An independent t-test compared PTS between sexes. Multiple regression analysis determined the effect of sex and stature and sex and limb length on PTS.ResultsFemale participants transitioned at a lower PTS than male participants (1.8 (0.2) m∙s^-1 versus 1.9 (0.1) m∙s^-1; p ≤ 0.026). Sex and stature explained 19% of the variance in PTS, while sex and limb length explained 21% of the variance. Including interactions increased the variance explained by 23% and 2% for sex and stature and sex and limb length, respectively. The significant interaction between sex and stature showed PTS was inversely proportional to stature for male participants but directly proportional for female participants.SignificanceThese findings suggest that the extent to which stature and limb length influence the preferred transition speed may differ between sexes.     

Three-dimensional viewing of and dosimetric calculations in Au-198 implants of the prostate.

A three-dimensional system for dosimetric calculation of radiation from interstitial brachytherapeutic implants was developed and was compared with conventional dosimetry performed with a commercial two-dimensional system. Software programs written for this study enabled the authors to place radioactive sources in the correct reconstructed anatomic locations, compute the isodose distribution around these sources, and display the isodose curves in their correct relationship to anatomic structures. Eight radiation oncologists evaluated the usefulness of both systems. Verification studies in phantoms and in 20 patients with gold-198 implants in the prostate gland showed that the experimental system was very accurate in volume reconstruction, seed localization, isodose distribution, point-dose calculation, and computation of dose-volume histograms. Although the dose depictions in the two systems matched almost exactly, statistically significant differences existed in interpretation of the dosimetric data generated by both systems. For example, the oncologists consistently believed that the dose to the prostate was lower when the three-dimensional system was used (P less than or equal to .0001).     

Age,perfusion test results and dipyridamole reaction

This retrospective study evaluated 933 patients referred for diagnostic nuclear medicine perfusion testing at 2 outpatient cardiology centers over a 7-month period. None of the patients were able to perform treadmill stress testing, and all received dipyridamole as a pharmacological stress. The authors found that 44% of the patients had an adverse reaction to dipyridamole. A correlational analysis of patients who did and did not have adverse reactions indicated that patients who exhibited some form of adverse reaction to dipyridamole were 10% more likely to have an abnormal perfusion test. In addition, age-group comparisons between patients 70 years or older and those younger than 70 years demonstrated that the younger group had a statistically greater probability of having an adverse reaction to dipyridamole.     

Inter-laboratory study on standardized MPS libraries: evaluation of performance,concordance, and sensitivity using mixtures and degraded DNA

International Journal of Legal Medicine - We present results from an inter-laboratory massively parallel sequencing (MPS) study in the framework of the SeqForSTRs project to evaluate forensically...