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PubMed1991

Swimming training increases the G4 acetylcholinesterase content of both fast ankle extensors and flexors.

The effect of endurance swimming training on AChE molecular forms was examined in 2 groups of functionally antagonist rat muscles, including ankle extensors and flexors. This exercise regimen, which entails predominant dynamic activity (i.e., involving extensive shortening) of both groups of muscles, resulted in marked selective G4 increases in all fast muscles. The G4 elevation exhibited by the ankle flexors was in sharp contrast to the G4 reduction reported in these same muscles following running training, during which their action is predominantly tonic. The results strengthen the conclusion that predominantly dynamic activity increases the G4 content of mature innervated fast muscles.

Acetylcholinesterase↗
PubMed1992

Force-length properties and functional demands of cat gastrocnemius, soleus and plantaris muscles.

The purpose of this study was to measure isometric force-length properties of cat soleus, gastrocnemius and plantaris muscle-tendon units, and to relate these properties to the functional demands of these muscles during everyday locomotor activities. Isometric force-length properties were determined using an in situ preparation, where forces were measured using buckle-type tendon transducers, and muscle-tendon unit lengths were quantified through ankle and knee joint configurations. Functional demands of the muscles were assessed using direct muscle force measurements in freely moving animals. Force-length properties and functional demands were determined for soleus, gastrocnemius and plantaris muscles simultaneously in each animal. The results suggest that isometric force-length properties of cat soleus, gastrocnemius and plantaris muscles, as well as the region of the force-length relation that is used during everyday locomotor tasks, match the functional demands.

Animals↗
PubMedDate not supplied

Relationship between ankle muscle and joint kinetics during the stance phase of locomotion in the cat.

The purpose of this study was to examine the relationship between internal force production in selected skeletal muscles and the externally calculated joint moment during overground locomotion in the adult cat. Hindlimb segments were modelled as a linked system of rigid bodies and a generalized muscle moment (GMM), the sum over all active and passive tissues acting about the joint, was calculated using principles of inverse dynamics. Moments produced by individual muscles were calculated using tendon transducers implanted in freely moving cats and muscle moment arm information. Results indicated that the externally measured variables of peak ground reaction force and joint position were equally important to the determination of peak ankle GMM. Examination of peak moments revealed that increases in peak ankle GMM were met by increases in medial (MG) and lateral (LG) gastrocnemius output. Peak soleus (SOL) moments did not change significantly as a function of peak ankle GMM. The role of the plantaris (PLT) was less clear, with peak moments increasing significantly as a function of peak ankle GMM in one cat. All four ankle extensors were important to the attainment of peak ankle GMM early in stance. Subsequently, SOL and PLT contributed substantially to the ankle GMM throughout stance, LG moments declined to near zero, soon after peak ankle GMM; and MG moments demonstrated a substantial but more gradual decline. The relative contributions of these individual muscles to the ankle GMM were supported by their respective architecture, uniarticular versus multiarticular function, and physiological profiles.

Animals↗
PubMed1993

Forces in gastrocnemius, soleus, and plantaris tendons of the freely moving cat.

The purpose of this study was to gain an insight into the mechanisms of force sharing among muscles in a functional group. Tendon force measurements were obtained simultaneously from gastrocnemius, soleus, and plantaris muscles of 10 cats during a variety of different locomotor tasks using strain gauge based force transducers. In particular, tendon forces were measured for conditions where movement speed was altered systematically, and where movement speed was kept constant but external resistance to walking was varied systematically. The results show that forces in the gastrocnemius and plantaris tendons increase with increasing intensities of movement, independent of intensity being altered by varying speed or external resistance. In contrast, peak soleus forces, on an average, remained nearly the same for all conditions; however, substantial modulations in soleus force were observed for consecutive stride cycles. These results suggest that soleus forces are not limited by peripheral (contractile) conditions but by central mechanisms and, further, that these central mechanisms depend on speed of movement and resistance to movement.

Achilles Tendon↗
PubMed1996

Soleus forces and soleus force potential during unrestrained cat locomotion.

It has been suggested that the soleus muscle in the cat is maximally activated during slow walking (e.g. Walmsley et al., Am. J. Physiol. 41, 1203-1216, 1978); however, this opinion is not shared throughout the scientific community (e.g. Hodgson, J. Physiol. 337, 553-562, 1983). Whether or not the soleus is maximally activated for low-demand movements is critical for understanding the interaction and force-sharing of the soleus with the remaining ankle extensor muscles. The purpose of this study was to test experimentally whether the soleus muscle was maximally activated during low-demand, unrestrained movements. In order to achieve this purpose, the soleus was stimulated supramaximally at different instants of the step cycle during walking using a chronically implanted nerve cuff electrode. Forces of the soleus during normal step cycles and during step cycles following supramaximal nerve stimulation were measured using a standard E-shaped tendon force transducer. For slow (0.4 m s-1) and intermediate (0.8 m s-1) speeds of walking, soleus forces could be substantially increased through supramaximal nerve stimulation during the swing and mid-stance phases of the step cycle; for fast walking (1.2 m s-1), such increases in force could be produced only during the swing phase. For all speeds of walking, the soleus forces could not be increased in the early (i.e. from paw contact to about peak force occurrence) or the late (i.e. the last 50-100 ms) parts of the stance phase. Specifically, peak forces and the rate of increase in force immediately following paw contact could not be increased substantially through supramaximal nerve stimulations at the appropriate instant in time for any of the conditions tested here. The results of this study indicate that force production of the soleus is maximal for fast walking (1.2 m s-1) throughout the stance phase, and is maximal for large portions of the stance phase for walking at slow (0.4 m s-1) and intermediate (0.8 m s-1) speeds. These findings have direct implications for explaining the possible mechanism of force-sharing among the cat ankle extensor muscles, and the in vivo mechanical properties of the soleus.

Animals↗
PubMed1987

Destructive cartilage loss in the joints of adult male broiler breeding fowls.

Patterns of destructive cartilage loss were studied in 60 male broiler breeding fowls. All showed destructive lesions in their hip or intertarsal joints and were between 18 and 62 weeks old when killed. Although surface regressive changes in articular cartilage were common, deep fibrillation, as seen in human and mammalian osteoarthrosis, was not identified. This difference probably reflects the more fibrous nature of articular cartilage in birds, but a number of similarities to hyaline cartilage degeneration were noted. Destructive cartilage loss resulted from partial or full thickness detachment of uncalcified cartilage. Clefts in deep cartilage preceded segmental detachment and occurred in cartilage with an intact articular surface. Detachment of segments of uncalcified cartilage may be the principal method of destructive cartilage loss in all avian species. It is concluded that clefts and destructive cartilage loss in adult broiler fowls can be a consequence of articular osteochondrosis or may result from osteoarthrosic lesions.

Acetabulum↗
PubMed1988

Further studies on collateral ligaments of knee and intertarsal joints in domestic fowl.

Collateral ligament attachments in distal femora and distal tibiotarsi were examined in broilers on ad libitum and restricted feeding and in laying strain fowls fed ad libitum. Histopathological studies revealed morphological changes in ligaments of ad libitum-fed broilers which were less apparent or absent in other birds examined. One such change was loss of crimp pattern in collagen bundles of ligaments, which suggested that structural derangement had occurred. Chondroid metaplasia and foci of hyaline cartilage were observed in ligaments of ad libitum-fed broilers and may result from tissue ischaemia. Similarities were noted between ligament attachments in broilers and Osgood-Schlatter disease in man; lesions in broilers may well have a similar aetiology. It is concluded that although feed restriction restores some semblance of normality in broiler ligaments, the propensity for abnormality remains and becomes apparent in heavier birds. Such reasoning casts doubt on the wisdom of modern broiler breeding practice where feed restriction can mask genotypic predisposition to clinical disease.

Animal Husbandry↗
PubMed1992

Epithelioid sarcoma in a dog.

A tumour in an 11-year-old male crossbred Fox Terrier, showing the clinical and pathological features of epithelioid sarcoma in man is reported. Clinical aspects, location, peculiar pattern of spread and evolution, together with histopathological and immunohistological findings of this rare tumour simulating a granuloma are described. Controversial histogenesis is discussed.

Animals↗
PubMed1975

Fine structure of tarsal sensory organs in the whip spider Admetus pumilio (Amblypygi, Arachnida).

The sensory organs on the tarsi of the antenniform first legs of the whip spider Admetus pumilio C. L. Koch (Amblypygi, Arachnida) were examined with the scanning and transmission electron microscope. At least four different types of hair sensilla were found: (1) thick-walled bristles, which have the characteristics of contact chemoreceptors (several chemoreceptive dendrites in the lumen plus two mechanoreceptors at the base); (2) short club sensilla, innervated by 4-6 neurons which terminate in a pore on the tip; they are possibly humidity receptors; (3) porous sensilla, which are either innervated by 20-25 neurons and have typical pore tubules, or they have 40-45 neurons but no pore tubules; both types are considered to be olfactory; (4) rod sensilla occur in clusters near segmental borders; they are innervated by only one large dendrite which branches inside the lumen. Other tarsal receptors are the claws, which correspond to contact chemoreceptors, and the pit organ which resembles the tarsal organ of spiders. Compared to other arthropod sensilla, the contact chemoreceptors are very similar to those of spiders, while the porous sensilla correspond structurally to olfactory receptors in insects; the club and rod sensilla seem to be typical for amblypygids.

Animals↗
PubMed1987

A computer-controlled system to perturb the ankle joint of freely standing cats trained to maintain a given force.

A computer-based system was developed to (1) train freely standing cats to match various target forces with the left hindlimb, (2) perturb the left ankle joint when the cat was maintaining a desired force and (3) compare reflex responses before and after decerebration. Cats quickly learned to stand unaided on 4 pedestals. During a training session, a range of target force windows was presented to the cat. A successful trial consisted of maintaining the force applied on the left rear pedestal within the target window for a preset time period. To assist the cat, a light was turned on whenever the force was within the target window. A food pellet reward was delivered by the computer after each successful trial. To test reflex responses, the position of the left hindlimb could be briefly perturbed by activating a servo-controlled printed motor configured to rotate the pedestal about the axis of the ankle joint. Perturbations that either flexed or extended the ankle joint were presented pseudo-randomly by the computer. This approach has been used to quantify the magnitude of muscle afferent volleys and the reflex EMG in ankle extensor muscles of normal and decerebrated cats, in response to similar mechanical perturbations. It has also been used to study dynamic features in the electroneurogram recorded from a cutaneous nerve by implanted nerve cuff electrodes, and the correlations among the electroneurogram, the vertical contact force applied on the pedestal and the force recorded from muscle tendons by implanted transducers. This approach may have general applications in the study of postural control, including the study of the discharge patterns of individual motor, sensory or spinal cord neurons in freely standing cats.

Animals↗
PubMed1993

A discrete adjuvant-induced monoarthritis in the rat: effects of adjuvant dose.

Much evidence suggests an important role for the nervous system in the pathogenesis of peripheral inflammatory conditions such as arthritis. The classical adjuvant-induced arthritis model in the rat is a severe condition in which polyarthritis is accompanied by widespread systemic disease, complicating the interpretation of data. We have developed an adjuvant-induced arthritis of the tibio-tarsal joint in the rat, using a low dose of Freund's adjuvant administered locally. Initial inflammation is followed, after 14 days, by chronic monoarthritis which is maintained without generalised effects or loss of use of the limb until at least 30 days postinjection. A higher dose of adjuvant produces contralateral inflammation and arthritis, but only after 14 days, and without the complicating effects seen in classical adjuvant disease. Indirect measures of arthritis (joint circumference, inflammation score and nociceptive threshold) correlate closely with the histological state of the joint, supporting the use of these indices. This model can be easily exploited by alteration of adjuvant dose, to determine the roles of the nervous system in the pathogenesis, maintenance and symmetrical spread of inflammatory arthritis.

Animals↗
PubMedDate not supplied

Neuromuscular evaluation using rat gait analysis.

We have developed a rat gait analysis model to evaluate if ankle angle and other associated gait parameters could consistently define normal peroneal nerve and anterior tibialis muscle function. The second part of the study was designed to determine if such a model would be useful to measure recovery of function after a peroneal nerve crush injury (NCI). A clear plexiglas tunnel was designed for high-speed frame videotaping and subsequent computergraphic gait measurement and analysis. Normal gait patterns for ankle angle, back height, step and stride lengths and the stance and swing times were determined in 8 rats. Data analysis demonstrated no significant left/right differences for any of the variables (ANOVA) with the exception of step length. Subsequently, 12 rats with a peroneal NCI were evaluated. All gait parameters evaluated from the injured side were significantly different from the uninjured side after injury except stride length. Ankle angle was the most sensitive outcome variable. Weekly gait analysis provided objective measurements as the ankle angle gradually returned to normal within 3 weeks. The rat gait model is a sensitive and reproducible method for non-invasive evaluation of neuromuscular function during nerve recovery after a peroneal crush injury.

Analysis of Variance↗
PubMed1992

Neuropeptide Y inhibits sympathetic neurotransmission in ipsilaterally innervated but not contralaterally reinnervated superior tarsal smooth muscle of the rat.

The superior tarsal smooth muscle (STM), which elevates the upper eyelid, normally is innervated by sympathetic neurons from the ipsilateral superior cervical ganglion that are not neuropeptide Y-immunoreactive (NPY-ir). Following neonatal ganglionectomy, this target is reinnervated by sympathetic nerves from the contralateral superior cervical ganglion that are strongly NPY-ir. We examined the effects of exogenously administered NPY on STM tone, response to norepinephrine, and sympathetic neurotransmission in ipsilaterally innervated and contralaterally reinnervated STMs. NPY (2-10 micrograms/kg iv) increased blood pressure but did not alter STM tone. Similarly, contractile responses to co-administered norepinephrine were not affected. These findings imply an absence of direct and indirect postjunctional actions of NPY on STM. Contractions elicited by stimulation of the cervical sympathetic nerve (1.5 Hz) were not affected by NPY on the contralaterally reinnervated side; however, ipsilateral contractions were decreased in a dose-dependent fashion, with an inhibition of about 40% at 10 micrograms/kg. We conclude that while the STM is unresponsive to exogenously administered NPY, this peptide exerts selective inhibitory effects on the ipsilateral NPY-ir-negative but not the contralateral NPY-ir-positive innervation. This suggests that the neonatally denervated STM is reinnervated by contralateral fibers that are functionally different from the normal ipsilateral innervation in being devoid of functional prejunctional NPY receptors.

Animals↗
PubMed1995

Capsaicin effects on substance P and CGRP in rat adjuvant arthritis.

The effects of capsaicin on the sensory neuropeptides substance P and calcitonin gene-related peptide were analyzed in the ankle joints and dorsal root ganglia (L2-L6) of adult female Lewis rats. The study included 23 normal rats and 23 arthritic rats, all injected subcutaneously with capsaicin (total dose 200 mg/kg bw). Another two groups of animals from a previous study, i.e., 23 normal rats and 23 arthritic rats not given capsaicin served as controls. Adjuvant arthritis was induced by inoculation with heat-killed mycobacteria. The morphological distribution of sensory neuropeptides was assessed by immunohistochemistry and the tissue concentrations were determined by radioimmunoassay. In normal rats, capsaicin significantly reduced the concentrations of substance P and calcitonin gene-related peptide in ankle joints (54 and 36%, respectively) as well as dorsal root ganglia (40 and 54%, respectively). In arthritic rats those pretreated with capsaicin had significantly lower concentrations of substance P and calcitonin gene-related peptide in dorsal root ganglia (19 and 42%, respectively) compared to the arthritic controls. In the ankle joints, however, only the SP concentration was reduced (42%). Notably, this was accompanied by a 40% reduction in inflammatory response as assessed by comparing the ankle joint weights of the experimental groups. In general, there was a good correlation between the neuropeptide concentrations in ipsilateral ankle joints and the corresponding dorsal root ganglia as assessed in individual rats. The present study of adjuvant induced arthritis shows that capsaicin administration reduces the otherwise up-regulated levels of sensory neuropeptides in dorsal root ganglia and ankle joints. However, capsaicin at the dose given can only mitigate, not completely prevent the development of joint inflammation. Nonetheless, the findings suggest that antineuronal therapy targeted against specific neurotransmitters may prove useful in inflammatory joint disease.

Animals↗
PubMed1991

Secretion of chondroitin 6-sulfotransferase and chondroitin 4-sulfotransferase from cultured chick embryo chondrocytes.

We found that chondroitin 6-sulfotransferase and chondroitin 4-sulfotransferase were released into the culture medium from the cultured chick embryo chondrocytes. Since the release of the sulfotransferases was observed not only in serum-supplemented medium but also in serum-free medium, the released sulfotransferases were unlikely to be derived from serum. Addition of ascorbate to the serum-free medium supported the continuous release of the sulfotransferases. Monensin, which is known to cause dilatation of the Golgi apparatus and to inhibit sulfation of proteoglycan, was found to affect the release of the sulfotransferases. In the presence of 10(-6) M monensin, chondroitin 6-sulfotransferase activity in the cell layer was decreased to less than one tenth of the control, and the rate of the release of the activity became much smaller than the control after the initial rapid release. The activity of chondroitin 4-sulfotransferase was also affected by monensin, but the reduction of the chondroitin 4-sulfotransferase activity in the cell layer was not so great as the reduction of chondroitin 6-sulfotransferase activity. Unlike to the microsomal sulfotransferases, both chondroitin 6-sulfotransferase and chondroitin 4-sulfotransferase released into the culture medium were retained in the soluble fraction after centrifugation at 100,000 x g for 60 min, and were not activated by detergent. pH optimum and requirements for sulfhydryl compounds of the released sulfotransferases were similar to those observed previously in the chondroitin sulfotransferases from chick embryo cartilage and from cultured chick embryo chondrocytes. These results suggest that chondroitin sulfotransferases, which are localized in the Golgi apparatus, may be secreted to the extracellular space in a soluble form under the culture conditions.

Animals↗
PubMed1996

Prednisolone reduces experimental arthritis, and inflammatory tissue destruction in SCID mice infected with Borrelia burgdorferi.

Glucocorticosteroids (GC) are widely used as anti-inflammatory agents. The effects of Prednisolone on the development of Borrelia (B.) burgdorferi-induced clinical arthritis and organ inflammation was studied in severe combined immunodeficiency (SCID) mice. The drug was administered orally at a dose of 3, 10 and 30 mg/kg, starting shortly before experimental infection of the mice. A dose dependent inhibition of arthritic joint swelling was observed. Full protection was obtained with 30 mg/kg until 21 days after infection, subsequently, mild joint swelling developed but progression and severity of the disease was considerably less than in the other treated as well as in the untreated mice. Inhibition of clinical arthritis coincided with reduction of inflammatory cell infiltration in the joints, liver and muscle. Prednisolone was ineffective when application was initiated after arthritis was fully developed, i.e., 22 days after infection. Since the activated endothelium plays a critical role in development of inflammatory lesions, the expression of the cellular adhesion molecules (CAMs) E-selectin, P-selectin, ICAM-1 and VCAM-1 was determined in vitro using the bEnd3 endothelial cell line. Stimulation with a sonicated B. burgdorferi preparation in the presence of the water-soluble compound Prednisolone-21-hemisuccinate considerably reduced expression of ICAM-1, and marginally also of E-selectin, whereas the level of P-selectin and VCAM-1 remained unaltered. Thus, downregulation of ICAM-1 might be a critical factor in Prednisolone-mediated inhibition of B. burgdorferi-induced inflammation; the flare up of the disease after the initial protection indicates that additional therapy, e.g. with antibiotics, is necessary.

Animals↗
PubMed1995

Effects of surgical denervation on substance P and calcitonin gene-related peptide in adjuvant arthritis.

The occurrence of substance P (SP) and calcitonin gene-related peptide (CGRP) was assessed in the ankle joints and dorsal root ganglia (L2-L6) by immunohistochemistry and radioimmunoassay (RIA) after unilateral sciatic nerve section in adjuvant arthritis. Nerve section in arthritic rats had no clear-cut effect on warmth, redness, and swelling of ankle joints, but significantly affected the occurrence of SP and CGRP. Immunohistochemical analysis showed an almost complete disappearance of SP-positive fibers in the ipsilateral ankle joint in normal rats after axotomy, whereas in arthritic rats occasional SP-positive fibers remained. In dorsal root ganglia, only occasional SP-positive cells could be detected in normal and arthritic rats after axotomy. A similar but somewhat less pronounced effect of axotomy was noted for neuronal CGRP-LI. RIA showed a decrease in SP in ankle joints by 45% in normal rats and 58% in arthritic rats; the decrease in CGRP was 41% and 47%, respectively. In dorsal root ganglia, the decrease in SP after surgical denervation was 25% in normal rats and 54% in arthritic rats; the decrease in CGRP was 18% and 27%, respectively. The tissue concentrations of SP and CGRP in ipsilateral ankle joints and dorsal root ganglia were consistently correlated in normal as well as arthritic rats. The present study shows that an interruption of the nerve supply to joints cannot fully prevent the development of arthritis, although it significantly reduces the occurrence of sensory neuropeptides.

Animals↗