基因多态性在盆底器官脱垂中的研究进展

盆底器官脱垂（Pelvic Organ Prolapse,POP）是遗传和环境因素共同作用引起的中老年妇女常见病,其发病率逐年上升。目前,环境因素已基本明确,而遗传因素尚未阐明。近年来,由于基因分型及遗传基因鉴定技术的快速发展,以及对盆底器官脱垂的群体调查及家系分析的增加,盆腔脏器脱垂的遗传研究有一定的进展,本文就其在基因多态性方面的发现做一综述。     

Finite element analysis of retroacetabular osteolytic defects following total hip replacement

Periprosthetic osteolysis in the retroacetabular region with cancellous bone loss is a recognized phenomenon in the long-term follow-up of total hip replacement. The effects on load transfer in the presence of defects are less well known. A finite element model incorporating a retroacetabular defect behind a cementless component was validated against a 4th generation sawbone pelvis. Computational predictions of surface strain and von Mises stresses were closely correlated to experimental findings. The presence of a cancellous defect increased von Mises stress in the cortical bone of the medial wall of the pelvis. At a load of 600 N this was under the predicted failure stress for cortical bone. Increases in the cup size relative to the acetabulum caused increased stress in the cortical bone of the lateral wall of the pelvis, adjacent to the acetabulum. We are confident that our modeling approach can be applied to patient specific defects to predict pelvis stress with large loads and a range of activities.     

林床清理对落叶松(Larix gmelinii)人工林土壤呼吸和物理性质的影响

林下可再生生物质资源的利用是当今森林资源利用的热点,通过林床清理可以获得廉价可再生生物质资源,但其对林分土壤碳收支的影响尚不清楚。运用红外气体分析法（IRGA法）连续两年观测了林床清理对落叶松（Larix gmelinii）人工林土壤呼吸及物理性质的影响,并估算了林床清理生物质资源利用对落叶松人工林碳收支的影响。结果表明：林床清理能够降低落叶松人工林的土壤呼吸,2a的平均值由2．20μmol·m^-2s^-1降低到1．18μmol·m^-2s^-1,平均降低幅度1．02μmol·m^-2s^-1,年呼吸总量由41．2μmol·m^-2a^-1降至22．4μmol·m^-2a^-1,而且,使土壤呼吸Q10值从2．33降低到2．22,R0值从0．61μmol·m^-2s^-1降至0．36μmol·m^-2s^-1;林床清理能够使林床土壤温度冬季低于对照,而夏季则有相反趋势,清理使得林床土壤湿度变化幅度加大,而且秋季和春季较对照低,而夏季偏高;林床清理使得表层土壤容重要比对照未清理样地高53％（P〈0．05）,土壤非毛管孔隙度比未处理样地低49．5％（P〈0．001）,毛管孔隙度较对照未清理降低约15％（P〈0．001）。林床清理导致林下生物质资源所储藏的碳非呼吸性释放约175．0mol·m^-2,当考虑到林床清理导致的土壤呼吸的降低作用时,所测定的2a内土壤净碳支出由175．0mol·m^-2降低至137．4mol·m^-2。林床清理措施增加生物质资源利用和其所导致的土壤呼吸释放减少,能够减少非冉生资源利用导致的碳释放压力。但仍然需要注意到林床清理使得土壤物理结构发生改变,可能不利于落叶松的生长和落叶松林生态系统的稳定。     

笼底类型对肉仔鸡行为的影响及其与胸囊肿发生率的关系

为研究笼养肉仔鸡胸囊肿发生的行为学机制,观察比较3种盒式笼(笼底分别由铁丝网、塑料片和竹竿组成)中肉仔鸡从3至6周龄的行为,以及胸囊肿发生率的差异。结果表明6周龄时,肉仔鸡在3种笼底上的伏卧行为虽无显著差异,但在行为格局中其比例最高(均在70%以上),而站立、行走和晃动3种行为之和仅占10%左右;竹竿笼底上的肉仔鸡行走频次、晃动频次和比例均显著高于铁丝和塑料笼底上的(均P<0.05),而竹竿笼底上的肉仔鸡胸囊肿发生率显著低于铁丝笼底上的(P<0.05);随着周龄增长,铁丝笼中肉仔鸡行走和晃动频次均减少,伏卧时间延长,胸骨承受的重量增大,这增加了胸部与铁丝网笼底接触及摩擦的几率和时间。实验结果说明,笼养肉仔鸡行为格局趋向静态单一化(动态行为频次降低,静态行为比例占优势)与其胸囊肿发病率的变化相一致,提示两者存在某种内在联系。这验证了我们提出的假设,即依赖于笼底类型和周龄的肉仔鸡行为趋向静态性是胸囊肿形成的必经环节。     

The effect of diet and covering fully slatted concrete floors with rubber strips on the intake,performance and cleanliness of dairy-origin bulls

Fully slatted concrete floors are prevalent in beef cattle housing. However, concerns have been raised about welfare of cattle accommodated on slats. The objective of this study was to evaluate the effect of diet and floor type on the intake, performance and cleanliness of dairy-origin bulls from a mean age of 8 months to slaughter at 15.5 months old. Forty-eight bulls, which had a mean initial live weight of 212 kg (SD = 23.7), were allocated one of four treatments which consisted of two floors and two diets, arranged in a 2×2 factorial design. The floors evaluated were a fully slatted concrete floor and a fully slatted concrete floor covered with rubber; while the diets offered were either a high concentrate diet or a grass silage-based diet supplemented with concentrates. Over the entire experimental period, floor type had no significant effect on intake. Interestingly, however, when bulls were offered concentrates ad libitum, those accommodated on rubber covered slats consumed more concentrates than those accommodated on concrete slats. No effect of floor type on intake was noted when bulls were offered the grass silage supplemented with concentrate diet. There were no significant interactions between floor and diet on animal performance. Animals accommodated on rubber covered slats had a significantly better performance than those accommodated on concrete slats, as assessed by live weight at slaughter and live weight gain/day (P < 0.01) and estimated carcass gain/day (P < 0.05). The diet offered had no significant effect on animal performance. Bulls accommodated on rubber covered slats were significantly cleaner than those accommodated on concrete slats on day 97 (P < 0.001), but there was no significant effect of floor type when measured at other time points in the experiment. It is concluded from this study that diet has an important role to play in assessing bulls’ responses in performance to the effect of covering concrete slatted floors with rubber. Bulls offered a high concentrate diet had a higher concentrate intake, higher performance but a similar feed conversion ratio (FCR) when accommodated on rubber covered slats compared to those accommodated on fully concrete slatted floors. Animals offered this intensive diet were less efficient (as measured by a higher FCR) than those offered a supplemented grass silage-based diet.     

Two-leg alternate loading model – A different approach to biomechanical investigations of fixation methods of the injured pelvic ring with focus on the pubic symphysis

The dorsal component of the pelvic ring is considered to be the most essential element for the stability of the pelvic ring. None of the current biomechanical set-ups include the effect of shear stresses by alternating loads that the pelvic ring has to withstand during walking. We hypothesize that a biomechanical test set-up with two-leg alternate loading will lead to stress imitation at the pubic symphysis that are more similar to existing strains than other test set-ups, and would, therefore, be more adequate for biomechanical testing of fixation methods.     

Directed Dopaminergic Neuron Differentiation from Human Pluripotent Stem Cells

Dopaminergic (DA) neurons in the substantia nigra pars compacta (also known as A9 DA neurons) are the specific cell type that is lost in Parkinson’s disease (PD). There is great interest in deriving A9 DA neurons from human pluripotent stem cells (hPSCs) for regenerative cell replacement therapy for PD. During neural development, A9 DA neurons originate from the floor plate (FP) precursors located at the ventral midline of the central nervous system. Here, we optimized the culture conditions for the stepwise differentiation of hPSCs to A9 DA neurons, which mimics embryonic DA neuron development. In our protocol, we first describe the efficient generation of FP precursor cells from hPSCs using a small molecule method, and then convert the FP cells to A9 DA neurons, which could be maintained in vitro for several months. This efficient, repeatable and controllable protocol works well in human embryonic stem cells (hESCs) and human induced pluripotent stem cells (hiPSCs) from normal persons and PD patients, in which one could derive A9 DA neurons to perform in vitro disease modeling and drug screening and in vivo cell transplantation therapy for PD.     

Decline of soil nitrogen mineralization and nitrification during forest conversion of evergreen broad-leaved forest to plantations in the subtropical area of Eastern China

We examined soil nitrogen (N) mineralization and nitrification rates, and soil and forest floor properties in one native forest: evergreen broad-leaved forest (EBLF), one secondary shrubs (SS), and three adjacent plantation forests: Chinese fir plantation (CFP), bamboo plantation (BP) and waxberry groves (WG) in Tiantong National Forest Park, Eastern China. All forests showed seasonal dynamics of N mineralization and nitrification rates. Soil N mineralization rate was highest in EBLF (1.6 ± 0.3 mg-N kg⁻¹ yr⁻¹) and lowest in CFP (0.4 ± 0.1 mg-N kg⁻¹ yr⁻¹). Soil nitrification rate was also highest in EBLF (0.6 ± 0.1 mg-N kg⁻¹ yr⁻¹), but lowest in SS (0.02 ± 0.01 mg-N kg⁻¹ yr⁻¹). During forest conversion of EBLF to SS, CFP, BP and WG, soil N mineralization rate (10.7%, 73%, 40.3% and 69.8%, respectively), soil nitrification rate (94.9%, 32.2%, 33.9% and 39%, respectively), and soil N concentration (50%, 65.4%, 78.9% and 51.9%, respectively) declined significantly. Annual soil N mineralization was positively correlated with total C and N concentrations of surface soil and total N concentration of forest floor, and negatively correlated with soil bulk density, soil pH and C:N ratio of forest floor across the five forests. Annual soil nitrification was positively correlated with total C concentration of surface soil and N concentration of forest floor, and negatively correlated with soil bulk density and forest floor mass. In contrast, annual soil nitrification was not correlated to pH value, total N concentration, C:N ratio of surface soil and total C concentration and C:N ratio of forest floor.