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41.
M. Boulangé J. C. Cnockaert G. Lensel E. Pertuzon B. Vigreux 《European journal of applied physiology》1979,41(1):17-25
Summary The effects of long-term fatigue upon maximal force and peak rate of tension development (PRTD) (dF/dt max) are studied in man (elbow flexors), in the rat (pseudo-isolated gastrocnemius muscle) and in the frog (isolated sartorius muscle). The muscles are fatigued by voluntary anisometric anisotonic contractions against an elastic resistance in man, and by maximal tetanic contractions in the frog and the rat. In man, the excitation level of the muscle is controlled by the integrated surface EMG of the biceps brachii. In the animals, the muscles are stimulated by a neurostimulator. The PRTD and the maximal isometric force are measured during fatigue tests.In man, frog and rat, the maximal voluntary isometric torque or the maximal force and the PRTD decrease initially more or less rapidly according to the power developed during the fatigue process, and then less rapidly. The relationship between PRTD and maximal force is linear in the animals and curvilinear in man.The variations of maximal force and PRTD are discussed in relation to the level of excitation of the muscles and of the composition in different motor units types and their spatio-temporal recruitment. From a biomechanical point of view, it seems necessary to study the behavior of the series elastic component during the evolution of long term fatigue. 相似文献
42.
David F. Cottrell 《Pflügers Archiv : European journal of physiology》1984,402(4):454-457
The effect of changes of temperature on the impulse activity of duodenal mechanoreceptors with afferent C-fibres was studied in acute electrophysiological experiments in chloralose-anaesthetised sheep. The impulse activity of 4 tension receptor units increased when the duodenal mucosa was cooled over the range 0–39° C. The impulse activity of 10 tension receptors was reduced when the mucosa was cooled. Temperature changes between 39° C and 52° C did not alter the discharge pattern of either type of tension receptor response. An additional unit, which may have been associated with pyloric circular muscle, was excited by cooling over the temperature range 0–39° C. This unit was insensitive to compression and was excited by close-intra-arterial injections of pentagastrin, nor-adrenaline, prostaglandin F2 and prostaglandin E2. The cold-sensitivity of mechanoreceptors in the duodenal muscularis externa may play a role in the reflexes regulating gastric emptying in experimental situations when duodenal chyme is cold. 相似文献
43.
Summary The mechanism of quinidine action on rabbit cardiac and skeletal muscle was examined with functionally skinned muscle-fiber preparations. By using these preparations we could correlate measurements of muscle tension with the effect of quinidine on the Ca2+ activation of the contractile proteins and on the Ca2+ uptake and release from the sarcoplasmic reticulum (SR).
Effect of quinidine on the contractile proteins. Quinidine concentrations above 0.5 mmol/l increased the maximal Ca2+-activated tension development 12% for papillary muscle and 5% for soleus (slow-twitch). Adductor magnus (fast-twitch) showed no significant change. Quinidine (0.1–1.0 mmol/l) also increased the submaximal Ca2+-activated tension development for the three muscle types (papillary muscle=soleus>adductor magnus) and shifted the [Ca2+]-tension curves to the left in a dose-dependent fashion.
Effects of quinidine on the Ca
2+ uptake and release from the SR. Sarcoplasmic reticulum of skinned fibers was loaded with Ca2+ (uptake phase), then Ca2+ was released by 25 mmol/l caffeine (release phase) giving a tension transient. The area under the tension transient was used to estimate the amount of Ca2+ released. Quinidine (>0.5 mmol/l) decreased the Ca2+ uptake (soleus>adductor magnus>papillary muscle) and increased the Ca2+ release [papillary muscle=soleus adductor magnus (only at 1.5 mmol/l, the highest concentration tested)] from the SR of all three muscles in a dose-dependent manner. Quinidine at low concentration (0.1 and 0.5 mmol/l) increased the caffeine-induced tension transient of papillary muscle and higher quinidine concentrations (1.0 and 1.5 mmol/l) decreased the caffeine-induced tension transient of soleus and adductor magnus during both the uptake and release phases. The decreased Ca2+ uptake of papillary muscle in 1.5 mmol/l quinidine was antagonized by increasing the free Mg2+ from 0.032 to 0.32 mmol/l.In summary, quinidine has similar mechanisms of action in all three muscles: increased Ca2+ activation of the contractile proteins, decreased Ca2+ uptake and increased Ca2+ release from the SR in functionally skinned muscle fibers. We conclude that quinidine-induced decreases in Ca2+ uptake by the SR could be responsible for quinidine-induced myocardial depression and that quinidine-induced increases in Ca2+ activation of the contractile proteins and Ca2+ release from the SR could be responsible for the increases in skeletal muscle contraction caused by quinidine. 相似文献
44.
张志奇 《杭州医学高等专科学校学报》2001,22(6):315-316
目的总结疝环充填式无张力疝修补术的手术经验和临床效果.
方法采用美国巴德公司的疝环充填物及网状补片施行无张力修补术52例
,观察手术时间、切口疼痛、术后患者自主能力的恢复、并发症、复发率及术后住院时间.结果平均手术时间35min,切口疼痛轻,术后5~8h就能下床活动,
并发尿潴留4例,阴囊水肿2例,切口积液1例,术后平均住院时间4d,随访2~12个月无1例复发.结论疝环充填式无张力疝修补术具有操作方便,术后恢复快,并发症少,复发率低的优点,是一种符合人体解剖结构的理想的疝修补术. 相似文献
45.
目的通过总结克氏针钢丝单张力带内固定治疗四肢不稳定性骨折的手术方法与疗效,探讨四肢不稳定性骨折的有效治疗措施.方法对46例髌骨、肱骨外科颈、尺骨鹰嘴、锁骨远端骨折和肩锁关节脱位的患者采用克氏针钢丝单张力带内固定.结果46例患者关节功能完全恢复,无明显后遗症.结论应用克氏针钢丝单张力带内固定技术治疗四肢不稳定性骨折,简单易行,稳定可靠. 相似文献
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49.
Milad Khasian Bradley A. Meccia Michael T. LaCour Richard D. Komistek 《The Journal of arthroplasty》2021,36(7):2379-2385
BackgroundIt has been hypothesized that increasing posterior tibial slope can influence condylar rollback and play a role in increasing knee flexion. However, the effects of tibial slope on knee kinematics are not well studied. The objective of this study is to assess the effects of tibial slope on femorotibial kinematics and kinetics for a posterior cruciate retaining total knee arthroplasty design.MethodsA validated forward solution model of the knee was implemented to predict the femorotibial biomechanics of a posterior cruciate retaining total knee arthroplasty with varied posterior slopes of 0°-8° at 2° intervals. All analyses were conducted on a weight-bearing deep knee bend activity.ResultsIncreasing the tibial slope shifted the femoral component posteriorly at full extension but decreased the overall femoral rollback throughout flexion. With no tibial slope, the lateral condyle contacted the polyethylene 6 mm posterior of the midline, but as the slope increased to 8°, the femur shifted an extra 5 mm, to 11 mm posterior of the tibial midline. Similar shifts were observed for the medial condyle, ranging from 7 mm posterior to 13 mm posterior, respectively. Increasing posterior slope decreased the posterior cruciate ligament tension and femorotibial contact force.ConclusionThe results of this study revealed that, although increasing the tibial slope shifted the femur posteriorly at full extension and maximum flexion, it reduced the amount of femoral rollback. Despite the lack of rollback, a more posterior location of condyles suggests lower chances of bearing impingement of the posterior femur and may explain why increasing slope may lead to higher knee flexion. 相似文献
50.
You-Hung Cheng Wei-Chun Lee Yi-Feng Tsai Hsuan-Kai Kao Wen-E Yang Chia-Hsieh Chang 《Journal of children's orthopaedics》2021,15(2):106
PurposeThis study aimed to compare the efficacy of decreasing leg-length discrepancy (LLD) and postoperative complications between tension band plates (TBP) and percutaneous transphyseal screws (PETS).MethodsThis retrospective study reviewed LLD patients who underwent temporary epiphysiodesis at the distal femur and/or proximal tibia from 2010 to 2017 (minimum two years follow-up). Efficacy of decreasing LLD was assessed one and two years postoperatively. Complications were classified with the modified Clavien-Dindo-Sink complication classification system. Knee deformities were assessed by percentile and zone of mechanical axis across the tibial plateau.ResultsIn total, 53 patients (25 boys, 28 girls) underwent temporary epiphysiodesis (mean age, 11.4 years). The efficacy of decreasing LLD at two years between the TBP (n = 38) and PETS (n = 15) groups was comparable. Seven grade III complications were recorded in six TBP patients and in one PETS patient who underwent revision surgeries for knee deformities and physis impingement. Four grade I and two grade II complications occurred in the TBP group. The mechanical axis of the leg shifted laterally in the PETS group and medially in the TBP groups (+7.1 percentile versus -4.2 percentile; p < 0.05). Shifting of the mechanical axis by two zones was noted medially in four TBP patients and laterally in two PETS patients.ConclusionMore implant-related complications and revision surgeries for angular deformities were associated with TBP. A tendency of varus and valgus deformity after epiphysiodesis using TBP and PETS was observed, respectively. Patients and families should be informed of the risks and regular postoperative follow-up is recommended.Level of evidenceLevel III 相似文献