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PubMed1980

Manipulatory forelimb movements in normal and pyramidotomized dogs.

Normal and unilaterally pyramidotomized dogs were trained to retrieve food from various test devices to allow an estimation of the importance of the pyramidal tract for forelimb movements. The effects of pyramidotomy were relatively weak on movements which to a least extent required use of distal muscles. They were strongest on movements in which wrist flexion and toes flexion and adduction were necessary to get hold of the food. The latter tasks, however, were also among the most difficult ones for normal dogs. The deficits of movements performed after pyramidotomy were similar as previously found in cats if allowance is made for generally weaker components of distal limb muscles in the dog than in the cat.

Animals↗

PubMed1980

Lymph drainage of the major joints of the porcine forelimb.

The lymph drainage of the major joints of the porcine forelimb was subjected to a critical examination. Commercial India ink was injected into the left elbow joint and right shoulder joint of an experimental pig. The shoulder joint was approached craniolaterally, the injection site being at the cranial border of the tendon of insertion of the infraspinatus muscle. The elbow joint was approached from the dorsolateral aspect. A suitable site for intra-articular injection into the elbow joint was found to be within an imaginary triangle formed caudal to the lateral epicondyloid crest of the humerus, the ventral border of the lateral head of the M. triceps brachii, and a line just dorsal to the olecranon. The lymph nodes of the neck and shoulder region were carefully exposed and examined for any discoloration due to the ink. The dissection of the lymph vessels and lymph nodes showed that the Lnn, axillares primae costae drained the elbow and shoulder joint after the intra-articular injection of India ink.

Animals↗

PubMed1981

Forelimb movements in cats with complete or partial bulbar pyramid lesions.

Adult cats were trained to use a forelimb to open a hinged door against resistance for a food reward. Normal cats performed the task with only toe or wrist motions. Cats with unilateral complete bulbar pyramid section showed persistent deficits in distal limb movements with toe fanning, wrist stiffness and pulling from elbow and shoulder. Partial medial or lateral pyramid lesions produced similar but less severe effects. These results suggest a significant role of the corticospinal system in distal limb movements and a lack of topographical localization of pyramid fibers related to these movements in cats.

Animals↗

PubMed1980

Regulation and potency in the forelimb rudiment of the axolotl embryo.

Anterior, posterior, dorsal and ventral halves of the pre-bud forelimb rudiment of tail-bud axolotl embryos can all give rise to normal limbs after the complementary half has been removed. A histological study of the regulation of the posterior half rudiment showed no requirement for mesodermal healing across the gap, and no proliferative zone. The development of the limb bud on the operated side lags behind that of the control bud for several weeks of larval life. When half limb rudiments and double half limb rudiments were grafted to the head they did not develop unless both the posterior and the dorsal margin were present. Double posterior and double dorsal halves could develop into duplications on this site, single halves formed normal or hypomorphic limbs. When half limb rudiments were grafted to the flank the anterior halves developed into normal limbs and the posterior halves into duplicate limbs. The results are interpreted to indicate that at the pre-bud stage the limb rudiment is a homogeneous group of cells with no internal regional subdivisions. Its regulative behaviour is thus similar to that of early embryos and different from the regeneration behaviour shown by adult organs.

Ambystoma↗

PubMed1995

Use of a type II external skeletal fixator for repair of delayed union in three calves with forelimb fractures.

Three calves, 3 to 6 months old, were admitted for evaluation and treatment of fractures of the forelimb that had resulted from use of forced extraction at birth. Each of these calves had clinical and radiographic evidence of delayed union of a fractured metacarpus. All calves were treated, using a type II external skeletal fixator consisting of 0.25-inch-diameter transcortical pins and acrylic connecting bars. Two calves required open reduction of the fracture to obtain anatomic alignment of the limb. On the basis of the 3 calves described here, it would appear that type II external skeletal fixators may be adequate for treatment of selected calves with delayed union of a fracture.

Animals↗

PubMed1993

Masseter muscle responses to forelimb nerve stimulation in the guinea pig.

These experiments were aimed at clarifying the spinal-masseteric connections by observing the effect of electrical stimulation of radial nerve afferents on masseter muscle activity. Spontaneous and evoked electrical responses of the masseter motor units were recorded with tungsten microelectrodes and analysed on computer. Results show that electrical stimulation of both radial nerves induces responses in single masseter motor units. The response patterns were characterized most frequently by excitation, but also by a sequence of excitation inhibition. The latency in masseter muscle responses were found to be lower in contralateral recordings: 18.26 +/- 4.04 msec (x +/- SD) compared with a latency of 24.3 +/- 5.25 msec in ipsilateral recordings. These observations confirm the hypothesis that somatosensory impulses eminating from the radial nerve participate in the postural control of the masseter muscle aimed at maintaining correct jaw position during forelimb displacement.

Animals↗

PubMed1993

Phosphoprotein phosphatase activity in regenerating forelimbs of adult newts, Notophthalmus viridescens.

Traditional signal transduction pathways appear to be operating during amphibian forelimb regeneration, as in other developing systems. A consistent picture appears to be developing that suggests that growth factors promoting proliferation during regeneration act through cAMP-independent mechanisms while factors that modulate differentiation and morphogenesis include signaling pathways in which cAMP participates. Although our understanding of these pathways is far from complete, it is becoming increasingly evident that further characterization of signal transduction events will facilitate (a) identifying major signaling substances, (b) determining the cellular events in regeneration that they modulate, and (c) defining the mechanisms through which they act. The present study demonstrates that PPtases, and in particular PTPases, can be studied in regenerating newt limbs. More importantly, this investigation demonstrates that there are progressive and significant increases in PPtase activity during regeneration. Moreover, the observed patterns of PPtase activity during regeneration conform to an emerging picture that ligands acting through receptors possessing intrinsic tyrosine kinase activity promote proliferation within the regeneration blastema. However, the substrates used in this study precluded acquiring insights about modulating effects of serine/threonine kinases (e.g., PKA and PKC). Nevertheless, these data suggest that activation of PPtases contribute to the orchestration of the diverse cellular activities required to regenerate a vertebrate appendage.

Animals↗

PubMed1993

Thyroxine-responsive unilateral forelimb lameness and generalized neuromuscular disease in four hypothyroid dogs.

Four dogs were examined because of unilateral forelimb lameness. For all dogs, results of physical examination, including complete neurologic examination, were unremarkable except for vague, intermittent signs of pain upon deep palpation of the affected limb. During electromyography, insertional activity, fibrillation potentials, and positive sharp waves were recorded symmetrically from all major muscle groups. Generalized neuromyopathy was diagnosed. All dogs were determined to be thyroid deficient, and L-thyroxine supplementation was initiated. The lameness resolved within 2 months in all dogs. During follow-up electromyography, abnormalities were not recorded from 3 of the dogs and were less severe in the fourth. Thyroxine supplementation was discontinued in 2 dogs, and lameness redeveloped. Lameness again resolved when supplementation was reinstituted.

Animals↗

PubMed1977

Anatomical evidence of one-sided forelimb dominance in the rhesus monkey.

1. Differences in muscle and bone weight in the right and left forelimbs have been studied in twelve Rhesus monkeys. 2. There is anatomical evidence suggestive of one-sided limb dominance in nine animals, dominance being right sided in six animals and left sided in three animals. 3. The mean weights of all muscles and bones are greater on the dominant side except for the pectoralis major, the teres major and the clavicle. 4. The mean weight of the pectoralis major is greater on the non-dominant side and that of teres major and clavicle is equal on the two sides. The significance of these findings has been discussed in the light of observations in human adults and foetuses.

Animals↗

PubMed1988

Fossil platyrrhine forelimb bones from the early miocene of Argentina.

Primate scapula and ulna fragments of uncertain taxonomic affinity (MACN-SC 101) have been recovered from the Pinturas deposits at Arroyo Feo, Santa Cruz, Argentina in association with Santacrucian (Early Miocene) land mammals. Least-squares regression of body weight on surface area and on height of the glenoid fossa of the scapula indicates an estimated mean weight of 3.6 kg for this individual. On the basis of qualitative and several metric features, the fossil scapula and ulna most closely resemble living platyrrhine monkeys. In estimated body weight and relative height of the coronoid process, the fossil is similar to arboreal quadrupeds, such as Cebus apella and Chiropotes. However, spinoglenoid, axilloglenoid, and axillospinal angles, length of lever arm, and length and breadth of the sigmoid notch imply behavioral similarity with larger species that also use their forelimbs extensively in climbing, such as Alouatta and Lagothrix. MACN-SC 101 may represent the incipient divergence of a generalized platyrrhine arboreal quadruped toward a more suspensory form.

Animals↗

PubMed1986

The growth of muscle nerves in relation to the formation of primary myotubes in the developing chick forelimb.

A study has been made of the development of muscle nerves to primary myotube clusters destined to become the flexor carpi ulnaris (fcu) and flexor digitorum profundus (fdp) muscles in the avian forelimb. Myotubes and nerves were identified by immunofluorescent techniques using antibodies to the heavy and light subunits of myosin and neurofilament, respectively. At stage 24 the main ventral nerve trunk (the brachialis longus inferior nerve; bli n) had entered the limb before the appearance of myotubes in the limb. At stage 25/26 the bli n within the ventral compartment of the forearm had given rise to the interosseus nerve (in n) and the medial-ulnar nerve (m-u n) at the junction of the stylopodium and zeugopodium. The first few myotubes of the fdp and fcu muscles were observed at this level within the ventral premuscle cell mass; however, no nerves projected toward these myotubes from either the in n or the m-u n at this time. At stage 26/27 the fcu and the fdp muscles each consisted of clusters of 20-40 myotubes; each cluster was clearly delineated within the ventral premuscle cell mass. By this time small groups of axons had left the in n and the m-u n to grow into the fdp and fcu myotube clusters, respectively; these axons formed the muscle nerves. At stage 28/29 the number of primary myotubes in the clusters composing the fdp and fcu muscles had greatly increased, as did the size of the muscle nerves; each muscle was still clearly identifiable within the ventral muscle mass. By stage 32 the fdp and fcu muscles had clearly separated and the muscle nerves had divided into several well-spaced branches within each muscle. The present observations show that the main nerve trunks grow into the limb before the formation of myotubes expressing myosin isozymes. When myotubes do form they appear in small clusters at specific sites within the premuscle mass, before muscle nerves appear; a distinct muscle is destined to form from each of these clusters. Muscle nerves first branch from the main limb nerves when the myotube cluster contains more than about ten myotubes.

Animals↗

PubMed1977

Changes in cyclic GMP levels during forelimb regeneration in adult Notophthalmus viridescens.

Cyclic 3', 5'-guanosine monophosphate (cGMP) was measured at eight stages of forelimb regeneration in adult newts and compared with the cGMP levels of non-regenerating control limbs. There was a significant increase in cGMP content during dedifferentiation followed by a sharp decrease to minimal levels at the cone stage. A second smaller increase in cGMP occurred between the cone stage and mid-differentiation, followed by a decrease to relatively constant levels approaching control values as differentiation progressed. The changes in cGMP during dedifferentiation and during the period of highest cell proliferation indicate that cGMP may play a role in these processes. The smaller increases in cGMP levels during differentiation may reflect a reduced rate of cell division in the differentiating tissues.

Animals↗

PubMed1986

Vitamin A enhances forelimb regeneration in juvenile leopard frogs Rana pipiens.

The effect of retinoids on forelimb regeneration in the leopard frog, Rana pipiens, was examined by the topical application of a concentrated solution of vitamin A palmitate to the amputated left limb stumps of 30 froglets. This treatment resulted in the enhancement of regeneration; regenerative outgrowths of experimental frogs were more frequent, larger in size, and had improved morphology compared to their untreated control counterparts. We conclude that vitamin A palmitate, topically administered in concentrated dosages, exerts a positive effect on the regenerative capacity of Rana pipiens.

Amputation, Surgical↗

PubMed1976

Ascending long spinal actions on forelimb motoneurons in the acute spinal cat.

Ascending long spinal reflex system were investigated by means of monosynaptic reflex testing in the acutely spinalized unanesthetized cat. 1. Hindlimb nerve stimulation gave bilateral facilitatory effects on the motoneuron pools of pectoralis major and physiological flexors of the forelimb such as biceps brachii, extensor carpi radialis, extensor digitorum communis, but elicited depressive effects on the physiological extensors such as triceps brachii, flexor carpi radialis, flexor digitorum profundus. 2. In the latissimus dorsi, which is the antagonist of pectoralis major, a depressive effect was elicited by the stimulation of ipsilateral hindlimb nerves, and a facilitatory effect by contralateral stimulation. 3. These effects were evoked mainly from group II afferent fibers in muscle as well as cutaneous nerves. 4. Intracellular recordings from motoneurons of extensor carpi radialis revealed EPSPs following stimulation of hindlimb nerves with time courses corresponding to those of the facilitatory effects. We failed to detect any potential changes in the motoneurons of flexor carpi radialis following stimulation of hindlimb nerves.

Afferent Pathways↗

PubMed1985

Afferent projections from forelimb muscles to the external and main cuneate nuclei in the cat. A study with transganglionic transport of horseradish peroxidase.

Muscular and cutaneous afferents from distal forelimb distributed to the cuneate and external cuneate nuclei have been demonstrated in cat with the method of transganglionic transport of horseradish peroxidase. Injections of the same tracer were also done in ganglia C7 to T6 to demonstrate the afferents to these two nuclei. It is concluded that only muscle afferents terminate in the external cuneate nucleus. Afferents from paw and forearm occupy sequential territories in the medial part of the nucleus, which are only partly exclusive. Afferents from individual flexor muscles of forearm occupy distinct sites but their distributions overlap with those of forearm extensor muscles. In the external cuneate nucleus, the distributions of afferents from individual muscles constitute integral parts of a segmental representation. In the cuneate nucleus, cutaneous afferents are located dorsally and terminate over cells of the "clusters". Muscle afferents are distributed in ventral regions and are topographically arranged. They terminate over "reticular" regions.

Animals↗

PubMed1985

Peripheral inputs and early unit activity in area 5 of the monkey during a trained forelimb movement.

Previous studies on area 5 in the monkey showed that an early neuronal activity up to 300 ms before the onset of movement was encountered in this cortical area after deafferentation of the trained forelimb (C1-T7). This present work indicates that none of the EMG activity recorded in other parts of the body may account for these early changes and lends weight to the hypothesis that their activation is purely central.

Animals↗

PubMed1985

Fatiguability and oxidative capacity of forelimb and hind limb muscles of dystrophic mice.

Fatigue indices and succinic dehydrogenase (SDH) activities were determined in the extensor digitorum longus (EDL) and soleus muscles of the hind limb and the extensor carpi radialis longus of the forelimb in control and dystrophic mice aged 4 to 26 weeks. A good correlation was found between SDH activities and fatigue indices in muscles from normal mice. In the dystrophic (dy2J) mice, however, this correlation was not present. The EDL muscles from 26-week-old dy2J mice showed a much higher resistance to fatigue than age-matched controls but this was not accompanied by a significant change in SDH. The increased fatigue resistance in dy2J EDL appeared between 8 and 12 weeks of age and was temporally correlated with the onset of fused bursts of spontaneous activity in the hind limb muscles. Nevertheless, there was no conclusive evidence for a link among this spontaneous activity, oxidative enzyme capacity, and fatigue resistance.

Animals↗

PubMed1986

Number and size of motoneurons in a forelimb motor nucleus of normal and dystrophic (C57BL/6J dy2j/dy2j) mice.

The method of retrograde axonal transport of horseradish peroxidase (HRP) was used to identify the motoneurons that innervate the distal forelimb muscles via the ulnar nerve in normal and dystrophic (C56BL/6J dy2j/dy2j) mice. In both normal and dystrophic mice this motor nucleus was located in spinal segments C6 through T1. No clear division, on the basis of size, into alpha and gamma motoneuron populations was apparent. The motoneurons of dystrophic mice were fewer in number (26.5 vs. 35) but larger in cross-sectional area (780 vs. 674 microns2) than those of age-matched control mice. These results are quantitatively similar to those reported for the hind limb soleus muscle of dystrophic mice and suggest that the motoneuronal changes are a reflection of the dystrophic process rather than the associated spontaneous action potential generation seen in the dystrophic hind limb muscles.

Animals↗