高水位条件下池杉根系的生态适应机制和膝根的呼吸特性

  池杉(Taxodium ascendens)属于典型的耐水树种, 掌握其根系对淹水环境的生态适应机制对于研究林木耐水机理十分重要。通过对江苏省里下河低湿地17年生池杉在高水位(6～10月淹水, 全年平均地下水位-5 cm)、中水位(8～9月淹水, 全年平均地下水位-18 cm)和低水位(常年不淹水, 全年平均地下水位-41 cm)条件下的根系进行调查, 结果表明, 池杉在高水位条件下形成细长的气生根, 气生根依附于树干北侧或潜伏于树干外表皮内侧和纵裂的树皮缝隙中; 中水位池杉能形成直径(7.9±2.2) cm、高(7.7±2.7) cm的膝根, 每株立木拥有膝根数(5.8±1.7)个; 低水位池杉也能形成膝根, 但个体小、数量少。林木地下和地上生物量均呈现出明显的高水位<中水位<低水位的趋势, 但是地下/地上生物量的比值却呈相反趋势, 表明池杉耐水性虽然很强, 长期处于较高水位时生长会明显受抑, 尤其是地上生物量生长受抑更显著。高、中和低水位池杉的地径/胸径之比分别是2.66±0.11、2.08±0.10和1.75±0.08, 说明水位较高的环境能促进树干基部的相对粗生长。长期淹水导致地下根的容重降低, 但是气生根和膝根的容重却明显大于地下根。高、中水位池杉细根的Fe和Mn浓度显著高于低水位, 其中Fe的浓度相差10倍以上, 但是叶的Fe、Mn浓度在不同水位之间没有显著差异。膝根的呼吸具有明显的季节差异, 8月和9月平均每个膝根的呼吸速率为2.1～2.5 mgCO₂&#8226;h^–1, 6月和11月为0.7～0.9 mgCO₂&#8226;h^–1, 3月为0.4 mgCO₂&#8226;h^–1; 膝根吸收O₂的摩尔数是释放CO₂摩尔数的4.6倍, 说明膝根吸收的O₂除了供自身呼吸, 大部分是提供给地下根利用。池杉之所以具有较强的耐水性, 与其在缺氧环境中能形成气生根和膝根、树干基部膨大和根系容重降低等有利于改善根系通气条件的生态适应机制密切相关。     

Protocol for constructing subject-specific biomechanical models of knee joint

A robust protocol for building subject-specific biomechanical models of the human knee joint is proposed which uses magnetic resonance imaging, motion analysis and force platform data in conjunction with detailed 3D finite element models. The proposed protocol can be used for determining stress and strain distributions and contact kinetics in different knee elements at different body postures during various physical activities. Several examples are provided to highlight the capabilities and potential applications of the proposed protocol. This includes preliminary results on the role of body weight on the stresses and strains induced in the knee articular cartilages and meniscus during single-leg stance and calculations of the induced stresses and ligament forces during the gait cycle.     

Technical note: a multi-dimensional description of knee laxity using radial basis functions

The net laxity of the knee is a product of individual ligament structures that provide constraint for multiple degrees of freedom (DOF). Clinical laxity assessments are commonly performed along a single axis of motion, and lack analyses of primary and coupled motions in terms of translations and rotations of the knee. Radial basis functions (RBFs) allow multiple DOF to be incorporated into a single method that accounts for all DOF equally. To evaluate this method, tibiofemoral kinematics were experimentally collected from a single cadaveric specimen during a manual laxity assessment. A radial basis function (RBF) analysis was used to approximate new points over a uniform grid space. The normalized root mean square errors of the approximated points were below 4% for all DOF. This method provides a unique approach to describing joint laxity that incorporates multiple DOF in a single model.     

Effects of the type of meniscal lesion on knee function

The relationship between the type of meniscal lesion (bucket-handle, flap or degenerative tears) and preoperative knee function (5.1±6.2 days before arthroscopic meniscectomy) was studied in 35 patients. Patients with bucket-handle tears (group B, n=12) had large knee extension work deficits during maximal voluntary contractions at 30° and 180°/s (Kin-Com dynamometer). These work deficits were accompanied by proportional decreases in the prime mover or agonist-EMG levels (VM: vastus medialis and/or VL: vastus lateralis). These patients had smaller deficits during flexion movements at 30°/s. Moreover, a larger number of negative clinical signs and symptoms (pain at rest and during tests, locking, thigh atrophy, extension and flexion movement deficits larger than 10°) were found with an equal or a higher prevalence in group B than in the other groups. Patients with flap tears (group F, n=15) had deficits in work and agonist-EMG activity (VM and VL) only during the extension tests. In contrast, patients with degenerative tears (group D, n=8) had a work deficit and a concomitant decrease in the EMG level of the medial gastrocnemius (MG), only during the flexion test at 30°/s. Comparable mean knee function scores, as measured by the Lysholm and Gillquist questionnaire [35], were obtained for the three groups of patients, suggesting that this measure was not sensitive enough to discern functional differences related to types of meniscal tears. The results of this study have demonstrated a link between the type of meniscal lesion and the consequent preoperative knee joint disability profile as defined by comparison with the sound leg. These results emphasize the need to consider meniscal lesion type and an individual's preoperative strength deficit when group comparisons of patients are made or the effects of therapy (arthroscopic surgery and rehabilitation) are evaluated.     

康复训练联合超激光对全膝关节置换术患者术后疼痛、膝关节功能和生活质量的影响

目的:探讨康复训练联合超激光对全膝关节置换术(TKA)患者术后疼痛、膝关节功能和生活质量的影响。方法:选取2016年1月-2017年9月期间在青海省人民医院疼痛科行TKA术式的患者73例为研究对象。根据随机数字表法将患者分为对照组(n=36)和研究组(n=37),对照组患者术后给予康复训练,研究组在对照组基础上联合超激光进行治疗,两组均治疗6周。比较治疗前、治疗6周后(治疗后)两组患者膝关节功能状况、疼痛程度、膝关节屈曲度和伸展度,同时随访3个月,观察两组患者生活质量情况。结果:两组患者治疗后视觉模拟疼痛量表(VAS)评分均较治疗前降低,且研究组低于对照组(P0.05)。两组患者治疗后膝关节伸展度、屈曲度、美国特种外科医院(HSS)评分均较治疗前升高,且研究组高于对照组(P0.05)。随访3个月,两组患者的生理功能(PF)、生理职能(RF)、躯体疼痛(BP)、总体健康(GH)、活力(VT)、社会功能(SF)、情感职能(RE)以及心理健康(MH)等评分较治疗前均升高,且研究组高于对照组(P0.05)。结论:TKA患者给予康复训练联合超激光治疗效果较好,可显著改善患者膝关节功能,减轻患者疼痛,提高患者生活质量。     

腓骨近端截骨术与全膝关节置换术治疗内翻型膝关节骨关节炎患者的对比研究

目的:对比腓骨近端截骨术、全膝关节置换术(TKA)两种术式治疗内翻型膝关节骨关节炎患者的效果。方法:选择2016年2月-2017年2月期间我院收治的98例(98膝)内翻型膝关节骨关节炎患者,以随机数表法分为对照组与研究组,每组各49例(49膝)。研究组给予腓骨近端截骨术治疗,对照组给予TKA治疗,比较两组患者手术时间、术中失血量、住院时间、术后并发症情况,比较术前与术后1年膝关节功能、膝部疼痛程度、关节活动度、内翻角、生活质量的变化情况。结果:研究组手术时间、术中失血量、住院时间均低于对照组(P0.05)。两组术后并发症发生情况对比无统计学差异(P0.05)。术后1年两组患者美国特种外科医院(HSS)膝关节评分、关节活动度高于术前,视觉疼痛模拟(VAS)评分、内翻角低于术前(P0.05),但两组间对比无统计学差异(P0.05)。术后1年两组患者生理职能、生理机能、社会功能、活力、躯体疼痛、情感职能、精神健康与总体健康评分均高于术前,且研究组各项评分高于对照组(P0.05)。结论:与TKA术式比较,腓骨近端截骨术治疗内翻型膝关节骨关节炎患者在手术时间、术中失血量、住院时间等临床指标中均占有优势,可显著改善患者的生活质量,且无严重并发症发生。     

初次膝关节置换术后放置引流管与否临床疗效的前瞻性对照研究

目的:分析对比初次膝关节置换术后放置和不放置引流管的临床疗效。方法:纳入2017年1月-2017年7月在青岛大学附属医院行初次膝关节双间室置换的患者107例(107膝),其中术后放置引流管组(实验组)54例,术后不放置引流管组(对照组)53例。分别观察比较两组患者的一般临床资料、住院天数。术前和术后第3天血红蛋白、红细胞压积、视觉疼痛模拟评分、膝关节屈曲度数以及两组患者术后出现发热、伤口问题、24 h内辅料渗透、输血情况的例数。结果:两组患者在年龄、性别组成、体重、身高、手术时间等一般临床资料之间以及术前血红蛋白、红细胞压积、视觉疼痛模拟评分、膝关节屈曲度数等方面均无明显差异(P0.05)。术后实验组患者在血红蛋白、红细胞压积、膝关节屈曲度数均高于对照组(P0.05)。在视觉疼痛模拟评分上,实验组患者术后第1天低于对照组(P0.05),但术后第3天两组无明显差异(P0.05)。实验组患者的住院天数、输血患者的数量低于对照组,而发热例数明显高于对照组(P0.05)。结论:初次膝关节置换术后不放置引流管更有利于患者术后的早期康复,并减少患者术后输血率,而且不增加并发症的发生。     

Intracellular Calcium Response of ACL and MCL Ligament Fibroblasts to Fluid-Induced Shear Stress

This study examines the real-time intracellular calcium concentration, [Ca²⁺]_i, response of canine medial collateral ligament (MCL) and anterior cruciate ligament (ACL) fibroblasts subjected to a fluid-induced shear stress of 25 dynes/cm². In experiments using a modified Hanks' Balanced Salt Solution (HBSS) perfusate, both cell types demonstrated a significant increase in peak [Ca²⁺]_i compared to respective no-flow controls, the response of MCL fibroblasts being nearly 2-fold greater than that of ACL fibroblasts. In studies where the cells were bathed in a medium of HBSS supplemented with 2% newborn bovine serum (NBS) and then introduced to flow with the same medium, ACL fibroblasts responded nearly 3-fold greater than MCL fibroblasts. Neomycin (10 mM), thapsigarigin (1 μM) and Ca²⁺-free media supplemented with EGTA (1 mM) were able to inhibit significantly the [Ca²⁺]_i response to flow with HBSS in both fibroblasts. Thapsigargin also blocked the NBS flow response in both cell types, while neomycin and Ca²⁺-free media significantly inhibited the ACL response. Our findings demonstrate that ACL and MCL cells are not the same. These differences may be related to the disparate healing capacity of the ACL and MCL observed clinically.