The temporal and spatial effects of reconstructive surgery on the atrophy of hindlimb muscles in anterior cruciate ligament transected rats.

After anterior cruciate ligament (ACL) injury, a decrease in muscle strength associated with muscle atrophy is frequently observed. The temporal and spatial effects of reconstructive surgery on muscle atrophy have not been examined in detail. This study aimed to 1) reveal the short and mid-term effects of reconstructive surgery on muscle atrophy, and 2) investigate the differences in the degree of atrophy after ACL reconstruction in the hindlimb muscles. ACL transection with or without reconstructive surgery was performed unilaterally on the knees of rats. Untreated rats were used as controls. At one or four weeks post-surgery, the relative muscle wet weights (wet weight/body weight) of the hindlimb muscles were calculated to assess atrophy. At one week post-surgery, muscle atrophy was induced by ACL transection and further aggravated by reconstructive surgery. Reconstructive surgery facilitated recovery from muscle atrophy in some muscles compared with those without reconstructive surgery (ACL transection alone) at four weeks post-surgery. Muscle atrophy after ACL reconstruction was greater in the rectus femoris and plantar flexors than in the semitendinosus and plantar extensors at one week post-surgery. These results indicate that reconstructive surgery exacerbates muscle atrophy in the first week post-surgery, while facilitating recovery between the first and fourth week post-surgery. After reconstructive surgery, muscle atrophy was observed not only in the quadriceps and hamstrings, but also in the lower leg muscles, suggesting the need for muscle strengthening interventions for the lower leg muscles as well as the quadriceps and hamstrings.

Inflammation and Fibrosis Induced by Joint Remobilization, and Relevance to Progression of Arthrogenic Joint Contracture: A Narrative Review.

Joint immobilization is frequently administered after fractures and ligament injuries and can cause joint contracture as a side effect. The structures responsible for immobilization-induced joint contracture can be roughly divided into muscular and articular. During remobilization, although myogenic contracture recovers spontaneously, arthrogenic contracture is irreversible or deteriorates further. Immediately after remobilization, an inflammatory response is observed, characterized by joint swelling, deposit formation in the joint space, edema, inflammatory cell infiltration, and the upregulation of genes encoding proinflammatory cytokines in the joint capsule. Subsequently, fibrosis in the joint capsule develops, in parallel with progressing arthrogenic contracture. The triggers of remobilization-induced joint inflammation are not fully understood, but two potential mechanisms are proposed: 1) micro-damage induced by mechanical stress in the joint capsule, and 2) nitric oxide (NO) production via NO synthase 2. Some interventions can modulate remobilization-induced inflammatory and subsequent fibrotic reactions. Anti-inflammatory treatments, such as steroidal anti-inflammatory drugs and low-level laser therapy, can attenuate joint capsule fibrosis and the progression of arthrogenic contracture in remobilized joints. Antiproliferative treatment using the cell-proliferation inhibitor mitomycin C can also attenuate joint capsule fibrosis by inhibiting fibroblast proliferation without suppressing inflammation. Conversely, aggressive exercise during the early remobilization phases is counterproductive, because it facilitates inflammatory and then fibrotic reactions in the joint. However, the adverse effects of aggressive exercise on remobilization-induced inflammation and fibrosis are offset by anti-inflammatory treatment. To prevent the progression of arthrogenic contracture during remobilization, therefore, care should be taken to control inflammatory and fibrotic reactions in the joints.

Low-level laser therapy attenuates arthrogenic contracture induced by anterior cruciate ligament reconstruction surgery in rats.

Therapeutic approaches to treat joint contracture after anterior cruciate ligament (ACL) reconstruction have not been established. Arthrofibrosis accompanied by joint inflammation following ACL reconstruction is a major cause of arthrogenic contracture. In this study, we examined whether anti-inflammatory treatment using low-level laser therapy (LLLT) can prevent ACL reconstruction-induced arthrogenic contracture. Rats underwent ACL transection and reconstruction surgery in their right knees. Unoperated left knees were used as controls. After surgery, rats were reared with or without daily LLLT (wavelength: 830 nm; power output: 150 mW; power density: 5 W/cm2; for 120 s/day). We assessed the passive extension range of motion (ROM) after myotomy at one and two weeks post-surgery; the reduction in ROM represents the severity of arthrogenic contracture. ROM was markedly decreased by ACL reconstruction at both time points; however, LLLT partially attenuated the decrease in ROM. One week after ACL reconstruction, the gene expression of the proinflammatory cytokine interleukin-1beta in the joint capsule was significantly upregulated, and this upregulation was significantly attenuated by LLLT. Fibrotic changes in the joint capsule, including upregulation of collagen type I and III genes, shortening of the synovium, and thickening were caused by ACL reconstruction and seen at both time points. LLLT attenuated these fibrotic changes as well. Our results indicate that LLLT after ACL reconstruction could attenuate the formation of arthrogenic contracture through inhibition of inflammation and fibrosis in the joint capsule. Thus, LLLT may become a novel therapeutic approach for ACL reconstruction-induced joint contracture.

Estimation model for lower extremity strength using gait movement measured with inertial sensor considering differences of sex and environment.

In this study, we propose a method for estimating lower extremity strength from daily gait movement. Gait movement is affected by sex and gait environment. Therefore, we examined correlation coefficient between lower extremity strength and gait movement based on sex and environment and created models for estimating lower extremity strength. As a result, when only male or female data were used for model constructing, the correlation coefficient between estimates and actual measurements of lower extremity strength were approximately 0.7 and the precision had a mean absolute error of approximately 0.1 N/kg. The accuracy of the estimates was higher than that when sex was considered.

Intra-articular injection of mitomycin C prevents progression of immobilization-induced arthrogenic contracture in the remobilized rat knee.

This study tested whether cell cycle inhibitor mitomycin C (MMC) prevents arthrogenic contracture progression during remobilization by inhibiting fibroblast proliferation and fibrosis in the joint capsule. Rat knees were immobilized in a flexed position to generate flexion contracture. After three weeks, the fixation device was removed and rat knees were allowed to freely move for one week. Immediately after and three days after fixator removal, rats received intra-articular injections of MMC or saline. The passive extension range of motion (ROM) was measured before and after myotomy of the knee flexors to distinguish myogenic and arthrogenic contractures. In addition, both cellularity and fibrosis in the posterior joint capsule were assessed histologically. Joint immobilization significantly decreased ROMs both before and after myotomy compared with untreated controls. In saline-injected knees, remobilization increased ROM before myotomy, but further decreased that after myotomy compared with that of knees immediately after three weeks of immobilization. Histological analysis revealed that hypercellularity, mainly due to fibroblast proliferation, and fibrosis characterized by increases in collagen density and joint capsule thickness occurred after remobilization in saline-injected knees. Conversely, MMC injections were able to prevent the remobilization-enhanced reduction of ROM after myotomy by inhibiting both hypercellularity and joint capsule fibrosis. Our results suggest that joint capsule fibrosis accompanied by fibroblast proliferation is a potential cause of arthrogenic contracture progression during remobilization, and that inhibiting fibroblast proliferation may constitute an effective remedy.

Controlling interfered area in interferential current stimulation by electrode-area patterning.

Interferential current therapy is a noninvasive therapy using simultaneously two or more medium-frequency currents passing through tissue. By controlling the interfered area of the current flows, selective stimulation is possible in target muscles, including deep muscles. However, controlling the interfered area or the intensity of the current precisely is still lacking. Using simulations based on a biological model of the thigh as well as electrical muscle stimulation (EMS) experiments, we investigated the influence of electrode area ratio in changing the interfered area of the currents. Simulation and experiments were conducted under the same conditions, whereby current signals were applied through electrodes placed on the quadriceps and hamstring with an electrode area ratio of either 1:1 or 3:1. A comparison of the simulation results showed that the interferential current density decreased near the larger area electrode but increased near the smaller area electrode. In addition, the EMS experiment also showed that the quadriceps were stimulated using electrodes in a 1:1 area ratio, and the hamstrings were stimulated using electrodes in a 3:1 area ratio. These results demonstrated the possibility of controlling the area application of interferential current through electrode area patterning.

Interaction between gastrocnemius muscle weakness and moderate exercise deteriorates joint integrity in rat knee.

The aim of this study was to determine the effect on the knee joint of the interaction between ankle muscle weakness and moderate exercise. Gastrocnemius muscle weakness was induced by intramuscular injection of botulinum toxin type A (BTX) in rats. Low-speed treadmill running (12 m/min for 60 min) was applied for 6 weeks in rats with and without BTX. Untreated animals were used as controls. After BTX injection, the gastrocnemius muscle weakness was confirmed by 3-D motion analysis in kinematic features of the hindlimb during locomotion as an increased maximal dorsiflexion angle during the stance phase. Serum biomarker analysis by enzyme-linked immunosorbent assay revealed that low-speed running decreased the catabolic effect on type II collagen. However, the inhibition of catabolism induced by running exercise was significantly counteracted by BTX injection. In addition, thinning of the cartilage layer and a reduction in the chondrocyte density was also found in the tibial plateau of the knee in the BTX-injected rats after running for 6 weeks. These data suggest that moderate exercise have a positive effect on joint homeostasis. However, ankle muscle weakness may alter the mechanical environment of the knee and impair the integrity of joint cartilage with moderate exercise.

Morphological changes in hind limb muscles elicited by adjuvant-induced arthritis of the rat knee.

We investigated qualitative and quantitative changes in rat hind limb muscles caused by complete Freund's adjuvant (CFA)-induced knee joint pain. One week after CFA injection, muscle atrophy was induced only on the CFA-injected side. Wet weight of the rectus femoris (RF) and soleus (SOL) muscles were significantly decreased by 20% and 19%, respectively. The reduction in cross-sectional areas by CFA was similar for fast and slow muscle fibers in the RF (10% vs 15%, respectively) and SOL muscles (16% vs 16%, respectively). At the light microscopic level, pathological changes were not found in the RF muscles on both sides, although the infiltration of mononuclear cells and muscle regeneration were found in the SOL muscles on CFA-injected and contralateral control sides. On the other hand, electron microscopy revealed degenerative changes in the RF and SOL muscles on the CFA-injected side. Interestingly, sarcomere hypercontraction, indicating overexercise, was observed to a limited extent in the SOL muscles on the control side. In conclusions, knee joint pain can trigger the rapid development of muscle atrophy with degenerative changes not only in thigh but also calf muscles. This indicates that early interventions to inhibit joint pain or inflammation may prevent muscle atrophy.

Injury and repair of the soleus muscle after electrical stimulation of the sciatic nerve in the rat.

To study injury and subsequent changes in skeletal muscles, the rat sciatic nerve was electrically stimulated at 50 Hz and muscle contraction was induced for 30 min. Muscle damage was classified into five types (hypercontraction, hyperstretching, Z band disorders, misalignment of myofilament and regions of scarce myofilaments) by electron microscopy and quantified by ultrastructural assessment. After electrical nerve stimulation, the percentages of the injured areas of the soleus muscle were 18.8 +/- 15.8% (mean +/- SD) at 0 h, 9.7 +/- 1.0% at 6 h, 22.0 +/- 23.6% at 12 h, 13.1 +/- 3.2% at 24 h, 4.9 +/- 6.0% at 3 days and 0.5 +/- 0.4% at 7 days. At 0 h, the vast majority of ultrastructural alterations were sarcomere hypercontraction. At 6 h, hypercontraction was not recognizable and sarcomere hyperstretching and Z band disarrangement constituted the major findings. At 12 h, when the injury reached its maximum, myofilament disorganization and hyperstretching were predominant. At 24 h or afterwards, the injury began to decrease and recovered to almost normal conditions by 7 days. There were very few necrotic muscle fibers in all specimens. It is considered that the muscle lesions in the present study were reversible, and recovered through changes in various types of sarcomere alterations. Z band streaming and free ribosomes were frequently found at 12 and 24 h, which may indicate repair processes rather than newly formed lesions.

Effects of short-term denervation and subsequent reinnervation on motor endplates and the soleus muscle in the rat.

The rat sciatic nerve was locally frozen, and changes in the nerve, motor endplates, and the soleus muscle were examined for up to 6 weeks by light and electron microscopy. The wet weights of denervated soleus muscles compared with contralateral values progressively declined to a minimum at 2 weeks after injury (60.7 +/- 2.5%) and began to reverse following 3 weeks. The sciatic nerve thoroughly degenerated after freezing. However, numerous regenerated myelinated and thin nerve fibers were observed at 3 weeks. They were considerably enlarged but still smaller than normal counterparts at 6 weeks postoperatively. Nerve terminals containing synaptic vesicles of endplates disappeared at day 1 and mostly reappeared at 3 weeks (about 70% of the endplates). All endplates examined were reinnervated at 4, 5, and 6 weeks. On the other hand, postsynaptic folds of muscle fibers seemed to be only slightly influenced by denervation or reinnervation. Ultrastructural alterations of myofibrils, in particular the loss of register, immediately appeared after denervation, spread progressively, peaked at 2 weeks, ameliorated following reinnervation, and became significantly normalized at 6 weeks after freezing. The proportion of type II fibers in the soleus muscle similary showed an increase and a decrease with a short delay in response to denervation and reinnervation, respectively. This study clearly demonstrated that the nerve supply affects the ultrastructural integrity of skeletal muscles. In addition, changes in the endplates and the soleus muscle evaluated in this study after short-term denervation are largely reversible following reinnervation.

Systemic reactive amyloidosis associated with Castleman's disease: serial changes of the concentrations of acute phase serum amyloid A and interleukin 6 in serum.

A case is reported of a 21 year old woman who suffered from Castleman's disease and systemic reactive amyloidosis. The serum concentrations of serum amyloid A (SAA) and interleukin 6 (IL-6) were extremely high and amyloid protein was immunohistochemically identified as AA. After surgical excision of a large retroperitoneal lymph node with the pathological findings of plasma cell type of Castleman's disease, both serum SAA and IL-6 declined, showing a similar pattern of reduction curves. All clinical symptoms and laboratory abnormalities greatly improved. The biochemical feature of Castleman's disease is abnormal production of IL-6 and this cytokine continuously may stimulate the synthesis of an amyloid precursor, SAA, causing systemic reactive (AA) amyloidosis. This pathogenetic theory is strongly supported by the present study.

Possible involvement of both N- and L-type voltage-dependent Ca channels in adrenergic neurotransmission of canine saphenous veins in low Ca2+ plus tetraethylammonium medium.

The involvement of N- and L-type voltage-dependent Ca channels (VDCCs) in adrenergic neurotransmission under the superfusion with 0.25 mM Ca2+ + 20 mM tetraethylammonium (low Ca2+ + TEA) medium has been studied by examining the effects of omega-conotoxin GVIA (omega-CTX) and dihydropyridine antagonists and agonist on transmural nerve stimulation (TNS)-evoked 3H overflow from canine saphenous veins preloaded with [3H]-noradrenaline. Nisoldipine (10 and 30 microM) and nifedipine (30 microM) reduced significantly the TNS-evoked 3H overflow in low Ca2+ + TEA medium, while the two dihydropyridine antagonists failed to suppress it in normal Krebs medium. Bay K 8644 (30 and 100 nM) produced a significant and concentration-dependent enhancement of the TNS-evoked 3H overflow in low Ca2+ + TEA medium. The enhancing effects of Bay K 8644 were antagonized by both 3 microM nisoldipine and 10 microM nifedipine. omega-CTX inhibited markedly the TNS-evoked 3H overflow in both normal Krebs and low Ca2+ + TEA media, the inhibition by omega-CTX being ten times more potent in low Ca2+ + TEA medium. Nisoldipine (30 microM), when combined with 1 nM omega-CTX, produced a further significant inhibition of the TNS-evoked 3H overflow in low Ca2+ + TEA medium. However, no additional inhibition by 30 microM nisoldipine was observed when omega-CTX concentration was raised to 2 nM. In the veins superfused with normal Krebs medium, nisoldipine (30 microM) did not affect the inhibitory effect of 10 nM omega-CTX on the evoked 3H overflow.(ABSTRACT TRUNCATED AT 250 WORDS)

Low Ca2+ plus tetraethylammonium medium: its usefulness in studying the effect of Ca antagonist on adrenergic neurotransmission.

The low Ca2+ + tetraethylammonium (TEA) medium enhanced electrically evoked norepinephrine release by 3.5-fold in canine saphenous veins. omega-Conotoxin GVIA (omega-CTX) inhibited the neurotransmission more markedly in low Ca2+ + TEA medium than in normal Krebs medium. This is the case for the inhibition by tetrodotoxin, though to a lesser extent. The inhibition by omega-CTX was competitively antagonized by elevating external Ca2+. The results indicate that low Ca2+ + TEA medium is useful for studying the effect of Ca antagonists on adrenergic neurotransmission, because omega-CTX acts more effectively in this medium.

Presynaptic sites of isolated canine saphenous veins are more sensitive to protein kinase C than postsynaptic ones.

Effects of protein kinase C (PKC) activators and inhibitors on both tritium overflow and contraction evoked by 40 mM KCl were studied in canine saphenous veins preloaded with [3H]norepinephrine (NE). 12-O-Tetradecanoylphorbol 13-acetate (TPA) and phorbol 12,13-dibutyrate (PDBu) at 10(-11)-10(-7) M enhanced concentration-dependently the KCl-evoked tritium overflow, which was antagonized by polymyxin B (10(-5) M) and staurosporine (10(-7) or 10(-6) M). PDBu (10(-8) and 10(-7) M), but not TPA, potentiated the KCl-induced contraction. Only staurosporine reduced the KCl-induced contraction in the presence of PKC activators. Polymyxin B (3 X 10(-5) M) which failed to inhibit exogenous NE-induced contraction attenuated both responses to KCl. Staurosporine (10(-6) M) suppressed not only both the responses to KCl but also exogenous NE-induced contraction. Phentolamine (10(-6) M) inhibited almost completely the KCl-induced contraction and augmented remarkably the evoked tritium overflow. PDBu (10(-8) and 10(-7) M) still potentiated both responses to KCl in the phentolamine-treated veins. An additional treatment with nifedipine (10(-6) M) inhibited markedly the potentiation of the KCl-induced contraction by PDBu in the presence of phentolamine without affecting the evoked overflow. These results suggest that PKC may modulate KCl-evoked NE release from the adrenergic nerve endings of canine saphenous veins and that PKC is more sensitive to presynaptic than postsynaptic sites.

A selective effect of protein kinase C activators on noradrenaline release compared with subsequent contraction in canine isolated saphenous veins.

1. Effects of protein kinase C (PKC) activators and inhibitors on both tritium overflow and subsequent contraction evoked by transmural nerve stimulation (TNS) were investigated in canine saphenous veins prelabelled with [3H]-noradrenaline. 2. Activation of PKC by stepwise increasing concentrations (0.01 nM-1 microM) of 12-O-tetradecanoylphorbol 13-acetate (TPA), phorbol 12,13-dibutyrate (PDBu) or mezerein caused a significant and concentration-dependent enhancement of the tritium overflow evoked by TNS, while the activators failed to affect the corresponding contraction except with the highest concentration of PDBu when the contraction was significantly reduced. Phorbol, which is inactive on PKC, had no effects on the tritium overflow and contraction induced by TNS. 3. PKC inhibitors, polymyxin B (1 and 10 microM) and the isoquinolinesulphonamide, H-7 (1 microM), inhibited significantly the phorbol ester-potentiated tritium overflow evoked by TNS with no effects on the contraction. H-7 and the related inhibitor H-8 at 10 microM reduced significantly both responses to TNS in the presence of TPA, while they suppressed only the TNS-induced contraction in the absence of TPA. 4. None of the PKC activators or inhibitors affected the spontaneous tritium overflow. 5. PDBu (0.01 and 0.1 microM) elevated resting tension of the veins more effectively than TPA and mezerein. 6. These results suggest that PKC may modulate electrically stimulated noradrenaline release from adrenergic nerve endings of the canine saphenous veins and the PKC activators may act more selectively on presynaptic than postsynaptic sites, but have no apparent effect on postjunctional noradrenergic mechanisms.

Interaction between chicken gizzard caldesmon and tropomyosin.

Chicken gizzard muscle caldesmon has been examined for ability to interact with tropomyosin from chicken gizzard muscle by using fluorescence enhancement of tropomyosin labeled with dansyl chloride (DNS) and affinity chromatography. The binding of caldesmon to tropomyosin was regulated by Ca2+ and calmodulin, i.e., at low ionic strength most of the caldesmon bound to tropomyosin-Sepharose 4B was co-eluted by adding calmodulin only in the presence of Ca2+, but not in its absence. This regulation by Ca2+ and calmodulin was also suggested by fluorescence measurements. Actin- and calmodulin-binding sites on the caldesmon molecule were located in the 38K fragment (Fujii, T., Imai, M., Rosenfeld, G.C., & Bryan, J. (1987) J. Biol. Chem. 262, 2757-2763). When 38K-enriched fraction was applied to the tropomyosin-Sepharose, the 38K fragment was retained by the column and could be eluted by adding Ca2+ and calmodulin.