Effects of streams on lignin degradation during foliar litter decomposition in an alpine forest

AimsStreams are widely distributed in alpine forests, and litter decomposition in which is an important component of material cycling across the forest landscape. The leaching and fragmenting effects as well as the unique environmental factors in streams may have significant impacts on lignin degradation during litter decomposition, but studies on this are lacking.
Methods Using litterbag methods, we investigated the dynamics of lignin mass remaining and concentration (percent litter mass, %) during the decomposition of four foliar litters, which varied significantly in the initial litter chemical traits, from the dominant species of Salix paraplesia, Rhododendron lapponicum, Sabina saltuaria, and Larix mastersiana under different habitats (forest floor, stream, and riparian zone) in the upper reaches of the Minjiang River.
Important findings After two year’s incubation, litter lignin mass remaining for a specific litter species varied significantly (p < 0.05) among habitats, with an order of stream < riparian zone < forest floor. Lignin was degraded substantially in the early stage of litter decomposition process, and the lignin concentration first decreased and then increased with the proceeding of litter decomposition, but varied significantly (p < 0.05) among different litter species. Lignin mass showed a general trend of decrease across the 2-year decomposition course. In addition, habitat type, decomposition period and microenvironmental factors (e.g., temperature, pH value and nutrient availability) showed substantial influences on lignin degradation rate. These results suggest that the traditional view that lignin was relatively recalcitrant with an increase of concentration in the early stage of litter decomposition is challenged, but the loss of lignin in the early phrase is in line with recent findings about the fate of lignin during litter decomposition. Moreover, the significant differences of lignin degradation rates among different decomposition period and habitat types indicated that local-scale environmental factors can play a significant role in litter decomposition and lignin degradation processes.     

Monte Carlo calculations of radiotherapy dose in “homogeneous” anatomy

Given the substantial literature on the use of Monte Carlo (MC) simulations to verify treatment planning system (TPS) calculations of radiotherapy dose in heterogeneous regions, such as head and neck and lung, this study investigated the potential value of running MC simulations of radiotherapy treatments of nominally homogeneous pelvic anatomy. A pre-existing in-house MC job submission and analysis system, built around BEAMnrc and DOSXYZnrc, was used to evaluate the dosimetric accuracy of a sample of 12 pelvic volumetric arc therapy (VMAT) treatments, planned using the Varian Eclipse TPS, where dose was calculated with both the Analytical Anisotropic Algorithm (AAA) and the Acuros (AXB) algorithm. In-house TADA (Treatment And Dose Assessor) software was used to evaluate treatment plan complexity, in terms of the small aperture score (SAS), modulation index (MI) and a novel exposed leaf score (ELS/ELA). Results showed that the TPS generally achieved closer agreement with the MC dose distribution when treatments were planned for smaller (single-organ) targets rather than larger targets that included nodes or metastases. Analysis of these MC results with reference to the complexity metrics indicated that while AXB was useful for reducing dosimetric uncertainties associated with density heterogeneity, the residual TPS dose calculation uncertainties resulted from treatment plan complexity and TPS model simplicity. The results of this study demonstrate the value of using MC methods to recalculate and check the dose calculations provided by commercial radiotherapy TPSs, even when the treated anatomy is assumed to be comparatively homogeneous, such as in the pelvic region.     

Biomechanical gait analysis of pigs walking on solid concrete floor

Inappropriate floors in pig pens and slippery floor conditions may cause leg problems that reduce animal welfare. Therefore the objectives of the present study were to characterise the walk of pigs on dry concrete solid floor, to evaluate whether pigs modify their gait according to floor condition, and to suggest a coefficient of friction (COF) that ensures safe walking on solid concrete floors for pigs. Kinematic (50 Hz video recordings in the sagittal plane) and kinetic (1 KHz force plate measuring three perpendicular ground reaction forces) data were collected from four strides of both the fore- and hindlimbs of 30 healthy pigs walking on dry, greasy and wet concrete floor with 10 pigs on each floor condition. The COF of the floor conditions were tested in a drag-test. The results from the gait analysis showed that the pigs adapted their gait to potentially slippery floors by lowering their walking speed and reducing their peak utilised COF on greasy and wet (contaminated) floors compared with dry floors. Moreover, the pigs shortened their progression length and prolonged their stance phase duration on greasy floor compared with dry and wet floors. Thus the greasy floor appeared the most slippery condition to the pigs, whereas the wet floor was intermediate to the other two conditions. The pigs walked with a four-beat gait, and the limbs differed biomechanically, as the forelimbs carried more load, received higher peak vertical forces and had longer lasting stance phases than did the hindlimbs. The utilised COF from the gait analysis indicated that a high floor COF (>0.63) is needed to prevent pigs from slipping and thus to ensure safe walking on dry concrete floors.     

Tail structure is formed when blastocoel roof contacts blastocoel floor in Xenopus laevis

The tail organizer has been assessed by such transplantation methods as the Einsteck procedure. However, we found that simple wounding of blastocoel roof (BCR) made it possible to form secondary tails without any transplantation in Xenopus laevis. We revealed that the ectopic expression of Xbra was blocked by inhibiting the contact between BCR and blastocoel floor (BCF), and wounding per se seemed to be not directly related to the secondary tail formation. Therefore, the secondary tail might be induced by the contact between BCR and BCF due to the leak of blastocoel fluid from the wound. This secondary tail was similar to the original tail in the expression pattern of tail genes, and in the fact that the inhibition of fibroblast growth factor signaling prevented the secondary tail induction. Our results imply that the secondary tail formation reflects the developmental processes of the original tail, indicating that simple wounding of BCR is useful for the analysis of tail formation in normal development.     

A new measure of growth efficiency: Skull base height

Skull base height increases significantly with better nutrition and health conditions, as seen in comparing 163 nineteenth to twentieth century dissecting-room skeletons (Terry Collection) with 237 modern American middle-class adults (forensic and willed skeletons). The increase parallels the change in pelvic inlet depth index, known to respond sensitively to nutrition, and in stature, and is over six times greater than the general skull size change. Skull base height (porion-basion) is easy to measure with depth gauge and sliding caliper, or by subtraction, and is in adults a sensitive indicator of childhood growth stress.     

A biomechanical model to assess the contribution of pelvic musculature weakness to the development of stress urinary incontinence

A biomechanical model of the female pelvic support system was developed to explore the contribution of pelvic floor muscle defect to the development of stress urinary incontinence (SUI). From a pool of 135 patients, clinical data of 26 patients with pelvic muscular defect were used in modelling. The model was employed to estimate the parameters that describe the stiffness properties of the vaginal wall and ligament tissues for individual patients. The parameters were then implemented into the model to evaluate for each patient the impact of pelvic muscular defect on the vaginal apex support and the bladder neck support, a factor that relates to the onset of SUI. For the modelling analysis, the compromise of pelvic muscular support was demonstrated to contribute to vaginal apex prolapse and bladder neck prolapse, a condition commonly seen in SUI patients, while simulated conditions of restored muscular support were shown to help re-establish both vaginal apex and bladder neck supports. The findings illustrate the significance of pelvic muscle strength to vaginal support and urinary continence; therefore, the clinical recommendation of pelvic muscle strengthening, such as Kegel exercises, has been shown to be an effective treatment for patients with SUI symptoms.     

Quantitative evaluation of the major determinants of human gait

Accurate knowledge of the isolated contributions of joint movements to the three-dimensional displacement of the center of mass (COM) is fundamental for understanding the kinematics of normal walking and for improving the treatment of gait disabilities. Saunders et al. (1953) identified six kinematic mechanisms to explain the efficient progression of the whole-body COM in the sagittal, transverse, and coronal planes. These mechanisms, referred to as the major determinants of gait, were pelvic rotation, pelvic list, stance knee flexion, foot and knee mechanisms, and hip adduction. The aim of the present study was to quantitatively assess the contribution of each major gait determinant to the anteroposterior, vertical, and mediolateral displacements of the COM over one gait cycle. The contribution of each gait determinant was found by applying the concept of an ‘influence coefficient’, wherein the partial derivative of the COM displacement with respect to a prescribed determinant was calculated. The analysis was based on three-dimensional measurements of joint angular displacements obtained from 23 healthy young adults walking at slow, normal and fast speeds. We found that hip flexion, stance knee flexion, and ankle-foot interaction (comprised of ankle plantarflexion, toe flexion and the displacement of the center of pressure) are the major determinants of the displacements of the COM in the sagittal plane, while hip adduction and pelvic list contribute most significantly to the mediolateral displacement of the COM in the coronal plane. Pelvic rotation and pelvic list contribute little to the vertical displacement of the COM at all walking speeds. Pelvic tilt, hip rotation, subtalar inversion, and back extension, abduction and rotation make negligible contributions to the displacements of the COM in all three anatomical planes.     

Electromyography of pelvic floor muscles

Pelvic floor muscles (PFM) are intimately involved in function of lower urinary tract, the anorectum and sexual functions, therefore their neural control transcends the primarily important somatic innervation of striated muscle, as they are directly involved in “visceral activity”. Neural control of pelvic organs is affected by a unique co-ordination of somatic and autonomic motor nervous systems. Visceral and somatic sensory fibres supply sensory information from pelvic organs; their input influences through central integrative mechanisms also pelvic floor muscle activity. Anatomically, somatic afferent and efferent nerves of the sacral cord segments, reflexly integrated at the spinal cord and brainstem level, conduct neural control of PFM. The inputs from several higher centres influence the complex reflex control and are decisive for voluntary control, and for socially adapted behaviour related to excretory functions.     

Pelvic Floor Muscle Biofeedback in the Treatment of Urinary Incontinence: A Literature Review

Biofeedback is efficacious in the training of the pelvic floor musculature in order to enhance continence. This article reviews the anatomy and physiology of micturition as the underlying rationale for pelvic floor muscle biofeedback in the treatment of urinary incontinence. It critically reviews 28 studies published in peer reviewed journals from 1975 to 2005 that were prospective, randomized studies with parametric statistical analyses, operationally defined patient selection criteria, treatment protocols and outcome measures. The overall mean treatment improvement for patients undergoing biofeedback for urinary incontinence was 72.61%. In 21 of 35 (60%) paired comparisons, biofeedback demonstrated superior symptomatic outcome to control or alternate treatment groups. Larger studies and a standardization of technology and methodology are required for more conclusive determinations.     

高密度聚乙烯多孔材料在创伤性眶底缺损整复的临床观察

目的：观察高密度聚乙烯多孔材料Medpor在眶底缺损修复中的临床应用效果,分析相关并发症的术后改善情况。方法：2001年1月起选取20例创伤性眶底缺损患者采用高密度聚乙烯多孔材料作为眶底填充材料实施眼眶重建术,同期选取16例常规钛金属修复作为对照。术后6m嘱患者进行复查评价两者的治疗效果;评价内容包括息者外貌、眼球功能和创伤性眶底缺损常见并发症的改善情况等;术前履术后6m头颅三维螺旋CT检查观察眶底缺损修复后眼眶结构的连续性。结果：36例患者术后面中部对称性都逐渐恢复,眼球的运动功能明显好转。创伤性眶底缺损常见并发症如眼球内陷、复视及眶下神经感觉迟钝术后明显改善,采用Medpor材料修复和常规钛金属修复的患者无明显差异。同期螺旋三维CT显示与钛金属修复相比,采用生物材料保持了眶结构的连续性,维持了正常眶容积。有利于缺损修复,骨缺损面积明显缩小。结论：研究表明高密度聚乙烯多孔材料操作容易,可塑性高,材料在体内可促进自体骨组织长入,具有较好的修复效果,时临床眼眶修复重建的手术治疗具有一定的指导意义。