3D-CT在前交叉韧带重建术后评估中的临床价值

本文旨在探讨三维重建CT(3D-CT)在前交叉韧带(ACL)重建术后膝关节的临床价值。本研究所有65例ACL损伤患者均采用单切口股骨和胫骨单骨道方法重建ACL,记录患者术前及术后12个月的Lysholm评分,及膝关节屈膝30°、13.6kg应力条件下KT-1000测量胫骨相对前移距离。全部患侧膝关节在术后1周内和12个月分别进行螺旋CT轴位容积扫描,并行MPR、SSD和MIP三维重建,观察ACL和骨隧道情况。结果发现全部患者手术前及术后12个月Lysholm评分和KT-1000(应力13.6kg)差异显著(P<0.05)。螺旋CT重建图像能够清晰显示ACL重建术膝关节骨隧道的改变及位置、ACL与髁间嵴的关系。术后1周内股骨和胫骨隧道直径分别约为(9.15±0.03)mm和(9.11±0.09)mm,12个月时隧道直径较术后1周分别增加约3%和12%,但其差别均无统计学上差异(P>0.05)。因此,本研究认为多排螺旋CT重建图像能够评价ACL重建术后膝关节,有助于指导术中定位及术后评估。     

Comparison of Bioabsorbable Suture Anchor Fixation on the Tibial Side for Anterior Cruciate Ligament Reconstruction Using Free Soft Tissue Graft: Experimental Laboratory Study on Porcine Bone

Purpose

The use of graft tissue fixation using bioabsorbable interference screws (BISs) in anterior cruciate ligament (ACL) reconstruction offers various advantages, but limited pullout strength. Therefore, additional tibial fixation is essential for aggressive rehabilitation. We hypothesized that additional graft tissue fixation using bioabsorbable suture anchors (BSA) would provide sufficient pull-out strength.

Materials and Methods

Twenty four fresh frozen porcine distal femur and patellar tendon preparations were used. All specimens were divided into three groups based on additional fixation methods: A, isolated BIS; B, BIS and BSA; and C, BIS and post cortical screw. Tensile testing was carried out under an axial load. Ultimate failure load and ultimate failure load after cyclic loading were recorded.

Results

The ultimate failure loads after load to failure testing were 166.8 N in group A, 536.4 N in group B, and 438 N in group C; meanwhile, the ultimate failure loads after load to failure testing with cyclic loading were 140 N in group A, 466.5 N in group B, and 400 N in group C. Stiffness after load to failure testing was 16.5 N/mm in group A, 33.5 N/mm in group B, and 40 N/mm in group C. An additional BSA fixation resulted in a significantly higher ultimate failure load and stiffness than isolated BIS fixation, similar to post screw fixation.

Conclusion

Additional fixation using a BSA provided sufficient pullout strength for ACL reconstruction. The ultimate failure load of the BSA technique was similar to that of post cortical screws.     

Acromiohumeral Distance During Neuromuscular Electrical Stimulation of the Lower Trapezius and Serratus Anterior Muscles in Healthy Participants

Context

Compromise to the acromiohumeral distance has been reported in participants with subacromial impingement syndrome compared with healthy participants. In clinical practice, patients with subacromial shoulder impingement are given strengthening programs targeting the lower trapezius (LT) and serratus anterior (SA) muscles to increase scapular posterior tilt and upward rotation. We are the first to use neuromuscular electrical stimulation to stimulate these muscle groups and evaluate how the muscle contraction affects the acromiohumeral distance.

Objective

To investigate if electrical muscle stimulation of the LT and SA muscles, both separately and simultaneously, increases the acromiohumeral distance and to identify which muscle-group contraction or combination most influences the acromiohumeral distance.

Design

Controlled laboratory study.

Setting

Human performance laboratory.

Patients or Other Participants

Twenty participants (10 men and 10 women, age = 26.9 ± 8.0 years, body mass index = 23.8) were screened.

Intervention(s)

Neuromuscular electrical stimulation of the LT and SA.

Main Outcome Measure(s)

Ultrasound measurement of the acromiohumeral distance.

Results

Acromiohumeral distance increased during contraction via neuromuscular electrical stimulation of the LT muscle (t₁₉ = −3.89, P = .004), SA muscle (t₁₉ = −7.67, P = .001), and combined LT and SA muscles (t₁₉ = −5.09, P = .001). We observed no differences in the increased acromiohumeral distance among the 3 procedures (F_2,57 = 3.109, P = .08).

Conclusions

Our results supported the hypothesis that the muscle force couple around the scapula is important in rehabilitation and scapular control and influences acromiohumeral distance.Key Words: subacromial impingement syndrome, real-time ultrasound, rehabilitation

Key Points

• Acromiohumeral distance increased during neuromuscular electrical stimulation of the lower trapezius muscle, serratus anterior muscle, and combined lower trapezius and serratus anterior muscles.
• The increase in acromiohumeral distance was not different among the 3 neuromuscular electrical-stimulation procedures.
• The muscle force couple around the scapula is important in rehabilitation and scapular control and influences acromiohumeral distance.

Optimal upper limb function depends on the ability to statically and dynamically position the shoulder girdle in an optimal coordinated fashion.^1,2 Suboptimal motor control is considered a risk factor for developing shoulder subacromial impingement syndrome.^3–14 Alterations in scapular motion have been linked to a decrease in serratus anterior (SA) muscle activity, an increase in upper trapezius muscle activity, and an imbalance of forces between the upper and lower parts of the trapezius muscle.¹⁵ This may adversely affect scapular positioning, resulting in reduced scapular upward rotation, increased anterior scapular tilt, and scapular winging.^4,9,16 In turn, scapular upward rotation and posterior tilt are considered vital for elevating the acromion and, hence, widening the subacromial space, thereby preventing impingement of the subacromial tissues.^17,18 Atalar et al¹⁹ suggested that reduced scapular mobility led to a decrease in acromiohumeral distance (AHD) during upper extremity abduction. Therefore, when developing rehabilitation strategies for patients with subacromial impingement syndrome, correcting neuromuscular control of the SA and trapezius muscles is important.^20,21Overall, researchers^22,23 have supported the theory that altered activity in the scapular rotator muscles is present in patients with subacromial impingement syndrome and have highlighted the role of scapular rotator muscle training as an essential component of shoulder rehabilitation. A clinical practice strategy, supported by research data, recommends that patients who have subacromial shoulder impingement and present with primary movement dysfunction of the scapula should be given strengthening programs targeting the lower trapezius (LT) and SA muscles.^24,25 The LT muscle is reported to increase posterior scapular tilt, and the SA muscle is believed to increase upward rotation of the scapula.² In turn, posterior scapular tilt and upward scapular rotation are associated with increased AHD.^17,18Authors^9,23,26–29 of electromyographic (EMG) studies have tested muscle activity in participants with subacromial impingement syndrome and in healthy persons. In patients with subacromial impingement syndrome, when the upper extremity was at rest and during flexion and abduction, the EMG signal amplitude of the upper trapezius muscle increased, whereas the EMG signal amplitude of the LT and SA muscles decreased.^30,31 These researchers have considered the immediate changes in the surface EMG activity of the scapular rotator muscles. However, to our knowledge, we are the first to use neuromuscular electrical stimulation (NMES) to stimulate the muscle groups of the LT and SA and evaluate the effect of muscle contraction in these muscles on the AHD. Neuromuscular electrical stimulation is used for various medical applications and is a common intervention during rehabilitation to improve function and motor control,³² prevent and treat shoulder pain,³³ increase range of motion,³⁴ and facilitate changes in muscle action and performance.³⁵ Therefore, the purpose of our study was to investigate whether stimulation of the LT and the SA muscles (separately and simultaneously) with NMES would increase the AHD and to investigate which muscle-group contraction or combination most influenced the AHD.     

Achievement of Targeted Posterior Slope in the Medial Opening Wedge High Tibial Osteotomy: A Mathematical Approach

High tibial osteotomy (HTO) for medial compartment knee osteoarthritis is preferred in the activity patient since it allows patients to return to sports and recreational activities similar to the preoperative level. The purpose of this study was to mathematically formulate medial and anteromedial opening gaps in the medial opening wedge HTO to achieve a targeted tibial posterior slope. The change of posterior slope angle was mathematically derived in terms of the medial and anteromedial opening gaps, and the medial opening angles. The derived equations were validated by comparing them with those directly measured by performing simulated HTOs. In the triangular geometries of osteotomy planes, measured from three-dimensional osteotomy models of 30 knee patients, the mean anteromedial, medial, and lateral included angles were 92.4°, 53.9°, and 33.7°, respectively, and the mean lateral–medial edge length was 53.3 mm. The ratio of the anteromedial opening gap to the posterior opening gap should be “sin(the medial included angle) × cos(the lateral included angle)/sin(the anteromedial included angle)” to maintain an intact posterior tibial slope angle. With the derived equations, surgeons can estimate the opening gaps and opening angles to get a targeted posterior tibial slope with a medial opening angle.     

Influence of Anthropometric and Mechanical Variations on Functional Instability in the ACL-Deficient Knee

Individual variations in joint anatomy, tissue mechanical properties, and muscle strength of the knee are believed to affect the clinical outcome of ACL-deficient patients, but the effects have not been studied systematically. The impact of individual anthropometric and mechanical variation on functional stability of the ACL-deficient knee was investigated in this study using a two-dimensional mathematical knee model. The model included the tibiofemoral and the patellofemoral articulations, four ligaments, the medial capsule, and four muscle units surrounding the knee. Simulations were conducted to determine tibial anterior translation as well as tibiofemoral and patellofemoral joint loading at a single selected position during early stance phase of gait. Incremental hamstring muscle forces were applied to the modeled ACL-deficient knee in order to examine the level of the hamstring muscle forces required to prevent abnormal tibial anterior translation relative to the femur. Simulations were repeated using incremental variations in the selected anthropometric and mechanical properties of the ACL-deficient knee. It was found that bony geometry of the knee joint, especially the slope of tibial plateau, strongly affected both the tibial translations in the ACL-deficient knee and the effectiveness of the hamstring muscles to compensate for the ACL deficiency. For instance, simulations indicated that, due to ACL deficiency, the tibial anterior displacement increased by 9.1 mm for a tibial slope angle of 4° compared to 15.2 mm for a tibial slope angle of 12°. Future outcome studies for ACL-deficient knee may be required to include individual anthropometric and mechanical parameters of the knee as covariants. © 2003 Biomedical Engineering Society. PAC2003: 8719Rr, 8719Ff, 8719St     

Motion Alterations After Anterior Cruciate Ligament Reconstruction: Comparison of the Injured and Uninjured Lower Limbs During a Single-Legged Jump

Context:

Asymmetries subsist after anterior cruciate ligament reconstruction (ACL-R), and it is unclear how lower limb motion is altered in the context of a dynamic movement.

Objective:

To highlight the alterations observed in the injured limb (IL) during the performance of a dynamic movement after ACL-R.

Design:

Cross-sectional study.

Setting:

Research laboratory.

Patients or Other Participants:

A total of 11 men (age = 23.3 ± 3.8 years, mass = 81.2 ± 17.0 kg) who underwent ACL-R took part in this study 7.3 ± 1.1 months (range = 6–9 months) after surgery.

Intervention(s):

Kinematic and kinetic analyses of a single-legged squat jump were performed. The uninjured leg (UL) was used as the control variable.

Main Outcome Measure(s):

Kinematic and kinetic variables.

Results:

Jump height was 24% less for the IL than the UL (F_1,9 = 23.3, P = .001), whereas the push-off phase duration was similar for both lower limbs (P = .96). Knee-joint extension (F_1,9 = 11.4, P = .009), and ankle plantar flexion (F_1,9 = 22.6, P = .001) were less at takeoff for the IL than the UL. The hip angle at takeoff was not different between lower limbs (P = .09). We found that total moment was 14% less (F_1,9 = 11.1, P = .01) and total power was 35% less (F_1,9 = 24.2, P = .001) for the IL than the UL. Maximal hip (P = .09) and knee (P = .21) power was not different between legs. The IL had 34% less maximal ankle power (F_1,9 = 11.3, P = .009) and 31% less angular velocity of ankle plantar flexion (F_1,9 = 17.8, P = .004) than the UL.

Conclusions:

At 7.3 months after ACL-R, motion alterations were present in the IL, leading to a decrease in dynamic movement performance. Enhancing the tools for assessing articular and muscular variables during a multijoint movement would help to individualize rehabilitation protocols after ACL-R.Key Words: knee, dynamic movement, hop test, rehabilitation

Key Points:

• Kinematic and kinetic alterations were demonstrated in the injured leg at 7.3 months after anterior cruciate ligament reconstruction.
• These alterations led to decreased jump height during a single-legged squat jump in the injured leg.
• Enhancing tools for assessing articular and muscular variables during a multijoint movement would help to individualize rehabilitation protocols after anterior cruciate ligament reconstruction.

Anterior cruciate ligament (ACL) reconstruction involving bone-patellar tendon-bone (BPTB) or hamstrings tendon grafts has been commonly used after ACL rupture.¹ Ligament reconstruction often requires a long period of recovery, with a return to sport typically around 6.2 months after surgery.² However, the return to high-performance pivoting sports is not ensured. Sixty-seven percent were unable to return to their preinjury sport participation levels by 12 months after surgery.³Postoperative follow up, therefore, is crucial to evaluate the functional states of patients and individualize rehabilitation programs to achieve optimal recovery. Currently, several variables can help to monitor postoperative follow up⁴: (1) clinical measures, such as edema, pain, mobility, and stability of the knee joint; (2) subjective measures, such as the subjective knee form of the International Knee Documentation Committee⁵; and (3) objective measures, such as the measurement of anterior translation of the tibia on radiographs and the assessment of muscular recovery. To evaluate muscular recovery, 2 main types of tests are performed: an isokinetic test⁶ and functional tests.^6,7 The uninjured limb (UL) is used as a reference, and the goal of rehabilitation is to increase side-to-side symmetry.^6,8–10The isokinetic test helps to quantify muscular recovery by measuring peak muscle torque of the extensor and flexor muscles of the knee joint. Some authors^1,11 have shown deficits in the quadriceps and hamstrings muscles after ACL reconstruction. However, this test solely focuses on the knee joint and does not take into account the multijoint dimension of movements performed in sport activities.¹²Functional tests use single-legged functional movements involving the hip, knee, and ankle joints to identify performance deficits between the lower extremities. During vertical jumps, jump height was 14% to 24% less in the injured leg (IL) than in the UL¹³ 6 months after ACL reconstruction. Mohtadi et al¹ concluded that the results of functional tests did not differ with graft location. Functional tests use movements performed in sport activities, but they do not allow the identification of the deficit variables⁷ in terms of specific limitations responsible for the decrease in performance. In addition, these tests do not allow deficits to be corrected during rehabilitation.Some authors^14,15 have suggested the development of joint adaptations during multijoint movements after ACL reconstruction, consisting of modified joint positions and range of motion of the lower limb joints. Decker et al¹⁴ reported greater hip-extension and ankle plantar-flexion angles at initial ground contact during landing in the injured group than in the control group, and Pfeifer and Banzer¹⁵ observed that the range of motion of the knee joint during cycle single-legged jumps was less in the IL than in the UL. For kinetic analysis, Ernst et al¹⁶ measured a lower maximal knee moment in the IL than the UL and equivalent maximal hip and ankle moments in both limbs. Castanharo et al¹⁷ studied maximal power during a bilateral vertical jump and also noted a decrease in maximal knee power and equivalent maximal hip power in the ACL group compared with the control group. In these studies, joint and muscular variables were analyzed independently.Therefore, the purpose of our study was to highlight the alterations observed in the IL during the performance of a dynamic movement after ACL reconstruction. Our aim was to bring additional information to the current knowledge in the field of movement analysis to help multidisciplinary teams improve rehabilitation after ACL reconstruction. We hypothesized that (1) jump height would be less in the IL than in the UL, (2) we would find kinematic alterations with a modification in the joint positions of the lower limb joints of the IL at takeoff, and (3) we would find kinetic alterations with decreases in maximal knee moment and power in the IL compensated for by an increase in hip and ankle maximal moments and powers.     

冷冻保存同种异体骨-ACL-骨移植后止点转归研究

目的：比较自体骨-前交叉韧带(ACL)-骨移植和冷冻保存同种异体骨-ACL-骨移植重建ACL后，韧带止点的组织学和生物力学转归。方法：将日本大耳兔和新斯兰兔各60只随机分成自体骨-ACL-骨移植组和二步令冻保存同种异体骨-ACL-骨移植组。术中及术后均不使用免疫抑制剂。术后4、8、12周分别切取ACL作大体、俎织学观察和生物力学测试。结果：自体骨-ACL-骨移植组和冷冻保存骨-ACL-骨移植组在4周时止点处组织学上已有纤维组织与骨相连，但未见“潮线”形成，而在12周时两组均有潮线形成；4周拉伸时，止点处断裂分别为60％、66．7％，而8周分别为13．3％、13．3％，12周时则分别为6．7％、6．7％。结论：两组在止点处有相似的生物力学性能和组织学愈合过程。     

应用PEEK材料cage颈前路减压椎间融合术治疗脊髓型颈椎病的疗效观察

目的：观察分析应用PEEK材料椎间融合器颈前路减压椎间融合术治疗脊髓型颈椎病的疗效.方法：应用PEEK材料椎间融合器颈前路减压椎间融合术治疗脊髓型颈椎病39例83节段,其中单节段6例,双节段22例,三节段11例.手术前后应用JOA评分评定手术效果.结果：术后随访36.1（10～50）个月,JOA评分术前为平均（8.9±1.4）分,术后末次随访时为（14.3±2.4）分,平均改善率为（66.3%±5.4%）,与术前比较差异有统计学意义（P ＜0.01）,优良率为76.9%.颈椎生理曲度、融合节段高度均恢复,以三节段者为佳.椎间融合率术后6、12个月分别为89.7%、100%.无并发症发生.结论：应用PEEK材料椎间融合器颈前路减压椎间融合术治疗脊髓型颈椎病的疗效可靠,能够提高和维持颈椎曲度和融合节段高度.     

Static and Dynamic Properties of Golgi Tendon Organs in the Anterior Tibial and Soleus Muscles of the Cat

The responses of tendon organs of the anterior tibial muscle have been studied during twitch contraction, passive stretch, fused tetanic contractions and sinusoidal stretching in Nembutal anesthetized cats. The majority of the tendon organs had similar thresholds to active contraction and passive stretch tension. Some tendon organs were found to discharge spontaneously in the relaxed muscle. An approximate power function relationship has been found between steady state impulse frequency and muscle tension. The receptor properties are compared with those of soleus tendon organs. It is concluded that static and dynamic properties of Golgi tendon organs in the anterior tibial and the soleus muscles fall within the same range of variation, and that apparent discharge dissimilarities can be explained as due to differences in muscle mechanics.     

前入路减压内固定术治疗胸腰椎爆裂骨折

目的：评价前入路减压植骨内固定治疗胸腰椎爆裂型骨折的效果。方法：对15例胸腰椎爆裂骨折患者行前路减压，切除椎体后缘骨块，解除对硬膜的压迫，上下椎体间植骨融合内固定。结果：随访6～24个月，平均9个月，神经功能平均有1级以上的恢复。植骨块全部融合，椎体高度恢复满意，椎管容量扩大，无骨片残留。结论：该术式疗效肯定，但要严格掌握手术要点、适应证。     

In Vivo Effects of Ovarian Steroid Hormones on the Expressions of Estrogen Receptors and the Composition of Extracellular Matrix in the Anterior Cruciate Ligament in Rats

Female athletes have a significantly higher rate of anterior cruciate ligament (ACL) injury than their male counterparts. Sex steroid hormones are considered to have an influence as risk factors for female ACL injuries. We hypothesized that estrogen and progesterone have specific and synergistic influences on the composition of extracellular matrix in ACL. By ovariectomy (OVX) followed by subcutaneous estradiol (E2) and/or progesterone (P4) replacement, 40 female rats were divided into 5 groups: E2, P4, combined E2 and P4 (EP), OVX control, and sham group. After 30 days, using undecalcified sections of knee joints in conjunction with immunofluorescence staining of estrogen receptor α and β (ERα and ERβ), collagen types 1 and 3, and cartilage oligomeric matrix protein (COMP), the immunoreactivities of these proteins in two distinct parts of ACL, proximal and middle portions, were compared semiquantitatively among experimental groups. By E2 replacement, the expressions of ERα in ACL fibroblasts were elevated compared to the OVX group. At the proximal portion, the immunoreactivities of type 1 collagen by E2 replacement, type 3 collagen by P4 replacement, and COMP by E2 or P4 replacement were significantly reduced. At the middle portion, the immunoreactivity of type 3 collagen was significantly elevated by E2 replacement. However, no differences were observed between the sham and OVX groups. These findings suggest that ACL is ER-dependent and that ovarian hormones alter ligament tissue composition, especially at the proximal portion. Female hormonal influences are partly involved in the biological properties of ACL.     

Aspects of the Cerebral Circulation During Non-REM Sleep in Healthy Controls and Psychiatric Patients, as Shown by Rheoencephalography

A total of 59 recordings of simultaneous EEG-cerebral electrical impedance plethysmography (REG), in which periods of wakefulness drifted into light sleep, were considered; 32 of these recordings were from 9 healthy subjects, 27 were from 7 psychiatric patients (schizophrenics and organic brain syndromes). Digital measurements of three REG parameters and of two carotid-vertebral artery blood transit times from representative samples of pulse-volume waves were made from awake parts of each recording and compared with similarly obtained measurements from the subsequent sleeping portions. For the total group none of the neck transit times' differences reached significance but there were significant REG decreases of 11 and 15 percent in Amplitude for the left and right hemispheres respectively. Inflow Angle similarly fell by 4 (L) and 5 (R) percent; and Percent Rise Time decreased by 11 (L) and 5 (R) percent. Psychiatric patients could be distinguished from control subjects by their significantly greater decreases with sleep in both Amplitude (10 and 4 times greater for left and right sides) and Inflow Angle (by factors of 3 and 2 similarly). Our REG findings support those of other workers using alternative invasive methods to investigate cerebral circulation during non-REM sleep in animals and man.     

健康成年女性内生雌激素的变化与脂类代谢关系的探讨

目的:研究健康成年女性内生雌激素的变化对脂类代谢的影响,为雌激素替代治疗(ERT)提供参考.方法:选择健康体检育龄妇女387例,年龄(21～50)岁,测定雌激素(E2)、孕激素(P)、载脂蛋白A-Ⅰ(apoA-Ⅰ)、载脂蛋白B(apoB)、高密度脂蛋白胆固醇(HDL-C)、低密度脂蛋白胆固醇(LDL-C)、总胆固醇(TC)、甘油三酯(TG)、脂蛋白a[LP(a)].并从中选取40例自愿者作月经周期中自体早排卵期(EF)和黄体期(LUT)对照.结果:月经周期中雌激素的周期性波动,会影响到脂类代谢,选取EF、LUT作配对比较,发现内生雌激素水平对apoA-Ⅰ、apoB、apoA-Ⅰ/apoB、HDL-C、LDL-C、LDL-C/HDL-C、TC、TC/HDL-C、TG有影响,对LP(a)无影响,其中LDL-C、LDL-C/HDL-C、TC/HDL-C水平在LUT均比EF明显低(P＜0.05).结论:健康成年女性月经周期中内生雌激素的波动对脂类代谢有影响,虽然对于多数脂类影响不显著,但对在绝经期前女性进行脂类检测和药物治疗监测时,对测定结果处于临界水平的标本,需将其考虑为重要影响因素之一,不注意这些波动可能会影响治疗和诊断.随年龄增长呈周期性变化的雌激素水平有下降趋势,脂类:TC、TG、LDL-C、apoB随年龄增长有增长趋势,作为心血管疾病的危险因素之一,是一个较长的渐进过程.     

Effects of Dietary Copper Loading on Livers of Rats: I. Changes in Subcellular Acid Phosphatases and Detection of an Additional Acid p-Nitrophenylphosphatase in the Cellular Supernatant During Copper Loading

Significant changes occurred in lysosomal structure and function as copper was metabolized by rat livers. Hepatic total acid p-nitrophenylphosphatase (pNPase) activity was markedly increased in copper-loaded rats, and this increase was almost completely accounted for by heat- and formalin-stable (HFS) acid pNPase. Heat- and formalin-labile acid pNPase was essentially unchanged. On a subcellular level, the microsomal and supernatant fractions reflected the greatest relative increase in HFS acid pNPase. Increases in lysosomal, HFS acid pNPase in the large-granule fractions correlated with increase in solubilized large-granule enzymes, LG I, with mol wt > 200,000. LG II, representng solubilized large-granule enzymes with mol wt < 200,000, remained unchanged. Marked increases in supernatant acid pNPase were principally accounted for by a sevenfold increase in a supernatant lysosomal-like enzyme, DEAE Pk 1, separated by DEAE cellulose chromatography. An additional enzyme, DEAE Pk 2A′, that was hardly or not detectable in normal rats, was consistently demonstrated and increased in copper-loaded rats. Serum HFS acid pNPase increased in copper-loaded rats, suggesting that the increased hepatic supernatant acid pNPase in part escaped into the circulating fluid. Copper was principally associated with cytoplasmic organelles and was highest in mitochondrial and lysosomal fractions.     

半月板摘除对行走状态膝关节韧带-肌肉受力影响的计算机仿真

本研究结合人体下肢行走步态,建立韧带-肌肉-半月板-骨骼的膝关节力学模型,分别对有半月板和无半月板(半月板摘除)进行仿真计算,获得并对比了平地行走周期内有、无半月板时的膝关节运动和受力的动态数据,所建立的动态模型与传统不含半月板的力学模型相比,更符合实际,提高了计算效率和精度,有助于指导各类膝关节半月板损伤手术后恢复运动和康复评价。     

Static Compressive Loading Reduces the mRNA Expression of Type II and X Collagen in Rat Growth-Plate Chondrocytes During Postnatal Growth

The mechanisms by which chondrocytes modulate longitudinal bone growth are not well understood. This in vitro study investigated the effects of loading on the mRNA expression pattern of key molecular components of the growth-plate related to the extracellular matrix (type II and type X collagen) and the PTH-PTHrP feedback loop. Short-term static compressive loading was applied to rat proximal tibial growth-plate explants. Four age groups at specific developmental stages were investigated. The spatial variation in the mRNA expression was compared among loaded explants, their contralateral sham controls, and uncultured growth plates from normal animals. Basic cell metabolism (18S rRNA) was unaffected by load. Results indicated a narrower spatial distribution of mRNA expression of type II collagen throughout the growth plate; similarly, a narrowed distribution of expression of type X collagen was noted in the lower hypertrophic zone of the growth-plate. This suggests that mechanical compression influences chondrocytes of the hypertrophic zone to alter their expression of specific genes encoding proteins of the extracellular matrix, while PTH-PTHrP receptor mRNA, a regulatory protein, remained unaffected by loading. The effects of compression were similar at the different stages of growth, suggesting that additional factors may be involved in the clinical progression of skeletal deformities observed during growth spurts. Although this study was done in vitro and limited to static loading, it furthers our understanding of growth-plate mechanobiology as a first step toward providing a scientific rationale for treating progressive musculoskeletal deformities.     

Influence of Hydration on Physiological Function and Performance During Trail Running in the Heat

Context:

Authors of most field studies have not observed decrements in physiologic function and performance with increases in dehydration, although authors of well-controlled laboratory studies have consistently reported this relationship. Investigators in these field studies did not control exercise intensity, a known modulator of body core temperature.

Objective:

To directly examine the effect of moderate water deficit on the physiologic responses to various exercise intensities in a warm outdoor setting.

Design:

Semirandomized, crossover design.

Setting:

Field setting.

Patients or Other Participants:

Seventeen distance runners (9 men, 8 women; age  =  27 ± 7 years, height  =  171 ± 9 cm, mass  =  64.2 ± 9.0 kg, body fat  =  14.6% ± 5.5%).

Intervention(s):

Participants completed four 12-km runs (consisting of three 4-km loops) in the heat (average wet bulb globe temperature  =  26.5°C): (1) a hydrated, race trial (HYR), (2) a dehydrated, race trial (DYR), (3) a hydrated, submaximal trial (HYS), and (4) a dehydrated, submaximal trial (DYS).

Main Outcome Measure(s):

For DYR and DYS trials, dehydration was measured by body mass loss. In the submaximal trials, participants ran at a moderate pace that was matched by having them speed up or slow down based on pace feedback provided by researchers. Intestinal temperature was recorded using ingestible thermistors, and participants wore heart rate monitors to measure heart rate.

Results:

Body mass loss in relation to a 3-day baseline was greater for the DYR(−4.30% ± 1.25%) and DYS trials (−4.59% ± 1.32%) than for the HYR (−2.05% ± 1.09%) and HYS (−2.0% ± 1.24%) trials postrun (P < .001). Participants ran faster for the HYR (53.15 ± 6.05 minutes) than for the DYR (55.7 ± 7.45 minutes; P < .01), but speed was similar for HYS (59.57 ± 5.31 minutes) and DYS (59.44 ± 5.44 minutes; P > .05). Intestinal temperature immediately postrun was greater for DYR than for HYR (P < .05), the only significant difference. Intestinal temperature was greater for DYS than for HYS postloop 2, postrun, and at 10 and 20 minutes postrun (all: P < .001). Intestinal temperature and heart rate were 0.22°C and 6 beats/min higher, respectively, for every additional 1% body mass loss during the DYS trial compared with the HYS trial.

Conclusions:

A small decrement in hydration status impaired physiologic function and performance while trail running in the heat.     

Examination of the Diagnostic Value and Estimation of the Chaos Phenomenon Joint Sounds Using in Temporomandibular Fractal Dimension

The aim of this study is to estimate the chaos phenomenon in temporomandibular joints （TMJ） sound using fractal dimension （FD）, and to examine the diagnostic value of the FD in comparing TMJ sounds produced by 6 asymptomatic and 25 symptomatic TMJ. Multiple mandibular opening and closing cycles recorded were used to calculate the waveform dimension and correlation dimension in the FD. Chaos in the TMJ sounds was estimated by the FD that was saturated with some constant value to an increase of embed- ding dimension. Results reveal that fractal analysis produces a high degree of reproducibility within, and similarity across subjects, and indicate that both FD values of the asymptomatic TMJ sounds are significantly higher than those of the symptomatic. These findings suggest that chaos is present in TMJ sounds and the difference in the FD is of diagnostic value in evaluation of pathological change in TMJ sound signals.