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PubMed1980

Modulation of polymorphonuclear leukocyte locomotion by synthetic amphiphiles.

The effect of synthetic amphiphiles, poly(ethyleneglycol) 6000 (PEG) esterified with saturated fatty acids (C2-C18), on the locomotion of polymorphonuclear leucocytes (PMNL) has been investigated. It was noticed that PEG-myristate (M-PEG; C14) stimulated the random locomotion of PMNL populations in concentrations up to about 1 g/l. By contrast, the esters with shorter aliphatic chains had negligible effects and those with longer chains, PEG-palmitate (P-PEG; C16) and PEG-stearate (S-PEG; C18) reduced the locomotion, irrespectively of concentration. The ability of the PMNL to be stimulated by an attractant liberated from normal human serum was slightly impaired with M-PEG, but not with P-PEG. The response to M-PEG of individual PMNL was heterogeneous in that some cells were stimulated and others were inhibited, but the average result was a reduction of the motility. This indicates that methods used for the study of the locomotion of cell populations do not always reproduce the true behaviour of the whole population, but rather of a selected subpopulation. It was also concluded that the different effects of M-PEG and P-PEG were probably not due to phagocytosis or selective binding of either substance, but rather due to dissimilar effects on the membrane structure of the PMNL, since (i) M-PEG perturbated the PMNL membrane more than P-PEG, as assayed by the release of superoxide anion (O2-) although the binding was smaller, and (ii) M-PEG and P-PEG increased and decreased the membrane fluidity, respectively, as measured with fluorescence bleaching and recovery after bleaching of labeled PMNL. The results indicate a subtle coupling between membrane structure and PMNL locomotion.

Cell Membrane↗
PubMed1980

A proposal for the definition of terms related to locomotion of leukocytes and other cells.

There is currently much confusion of terms relating to locomotion of leukocytes and other cells. Standardized and precise use of terms is, however, indispensable for analysis of the basic mechanisms controlling such locomotion. The present proposal is intended to serve as a basis for a standardized system of reporting locomotor behaviour of leukocytes and other cells and their responses to environmental stimuli. Definitions of the terms random locomotion, directional locomotion, chemotaxis, chemokinesis, and intrinsic locomotor capacity are proposed. Examples are given to demonstrate the application of the terms in the experimental and clinical analysis of cell locomotion.

Cell Movement↗
PubMed1982

Locomotion of human lymphoblasts towards glucose and other sugars. Effects of pH, temperature and oxygen.

The effect of basic physical and chemical changes in the environment on the locomotion of human lymphoblasts was studied. The lymphoblasts were obtained by culture of human blood lymphocytes either with mitogens or in mixed lymphocyte culture. Lymphoblasts required glucose for optimal locomotion, and, if placed in glucose free media, they migrated towards glucose sources. A filter checkerboard assay showed chemokinesis and was suggestive of chemotaxis to glucose. Among other sugars tested only mannose enhanced locomotion, and products of glycolysis such as lactate and pyruvate inhibited locomotion. Lymphoblast locomotion was inhibited by azide, fluoride and 2-deoxyglucose but the effect of 2-deoxyglucose could be reversed by the addition of glucose. Lymphoblasts migrated faster at 40 degrees C than at 37 degrees C and their pH optimum was between 7.1 and 7.4. They migrated well in anaerobic conditions.

Carbohydrates↗
PubMed1980

Effects of human IgG on locomotion of human neutrophils related to IgG binding of a hydrophobic probe.

Heat-denatured (63 degrees) human IgG had complex effects on locomotion of human neutrophils. At concentrations of 1 mg/ml and below, it stimulated chemotactic locomotion into filters judged by the leading front assay, however, pre-treatment of the cells or of the filters with denatured IgG caused a reduction in the number of locomoting cells, compared to cells locomoting in a medium containing albumin. These effects took place in complement-free media. Native IgG was not chemotactic. The chemotactic activity of denatured IgG correlated well with increased binding by the same IgG preparations of the hydrophobic probe, 1-anilinonaphthalene-8-sulphonate (ANS), and it is suggested that heating induces a conformational change in the IgG molecule which allows recognition of the altered molecule by neutrophils and activation of a chemotactic response. The integrity of the Fc fragment is required for this activity. As well as a direct chemoattractant activity of IgG, evidence for release of chemotactic factors by cells in contact with aggregated IgG was also obtained. It is suggested that the contrary effects of denatured IgG on neutrophil locomotion are explicable if the protein, like other denatured proteins, activates the sensory chemotactic mechanism in the neutrophil, while at the same time causing a modification of adhesion of cell to substratum which may impair the locomotor capacity of the cells.

Anilino Naphthalenesulfonates↗
PubMedDate not supplied

[Induced locomotion in the myriapod Julus sp].

Coordinated locomotor activity in the decapitated millipede Julus sp. was induced either by mechanical stimulation of the legs with the aid of a treadmile band, or by electrical stimulation of separate parts of the abdominal nervous cord. For the walking induced by mechanical stimulation of the legs, it was shown that: 1) after the "support phase", an additional phase of locomoter cycle, i. e. a "pause phase", is registered; 2) the relationships between kinematic parameters are similar to those recorded during normal walking of the intact millipede and correspond to walking at the lowest velocity. In the case of locomotion induced by electrical stimulation, a "start locomotion threshold" was observed: if stimulation level exceeds this threshold, forward walking is induced being the faster the stronger this stimulation. Besides, the second threshold phenomenon was found - a "threshold of the reversion of locomotion direction". When this threshold is exceeded, forward walking is replaced by backward one. The relationships between kinematic parameters of locomotion induced by electrical stimulation are also similar to corresponding relationships of normal spontaneous walking in the intact millipede, although in this case a "pause phase" is absent.

Animals↗
PubMed1989

Variations in blood supply allocations for quadrupedal and for bipedal posture and locomotion.

Hemodynamics and orthodynamics were investigated in quadrupeds (dogs) and in bipeds (humans). The subjects were investigated at rest in supine or lateral posture, in quadrupedal and then in bipedal posture, and during locomotion. Quadrupedalism in humans was with subjects on their hands and knees. Bipedalism in dogs was on hindlimbs with the forelimbs held by a technician. Blood flow in the main arteries of the body (aorta, external and internal carotid, subclavian, and femoral) was measured by sonography. Positional variations between the main bones of the body were determined from X-rays. This study investigated the reallocation of blood supply to different regions of the body when it switches from quadrupedal to bipedal posture and locomotion. Compared with resting posture, the principal findings are 1) cardiac output shows a minimal increase for humans in bipedal stance and a noticeable increase for dogs as well as humans in quadrupedal stance; 2) quadrupedal stance in humans and dogs and bipedal stance in dogs require increased blood supply to the muscles of the neck, back, and limbs, while human bipedal stance requires none of these; 3) cerebral blood flow (internal carotid) in humans did not change as a result of bipedal posture or locomotion, but showed a noticeable drop in quadrupedal posture and an even further drop in quadrupedal locomotion. The conclusion is that erect posture and encephalization produced a noticeable readjustment and reallocation of blood flow among the different regions of the body: This consisted in shifting a large volume of blood supply from the musculature to the human brain.

Adolescent↗
PubMed2005

Role of the prehensile tail during ateline locomotion: experimental and osteological evidence.

The dynamic role of the prehensile tail of atelines during locomotion is poorly understood. While some have viewed the tail of Ateles simply as a safety mechanism, others have suggested that the prehensile tail plays an active role by adjusting pendulum length or controlling lateral sway during bimanual suspensory locomotion. This study examines the bony and muscular anatomy of the prehensile tail as well as the kinematics of tail use during tail-assisted brachiation in two primates, Ateles and Lagothrix. These two platyrrhines differ in anatomy and in the frequency and kinematics of suspensory locomotion. Lagothrix is stockier, has shorter forelimbs, and spends more time traveling quadrupedally and less time using bimanual suspensory locomotion than does Ateles. In addition, previous studies showed that Ateles exhibits greater hyperextension of the tail, uses its tail to grip only on alternate handholds, and has a larger abductor caudae medialis muscle compared to Lagothrix. In order to investigate the relationship between anatomy and behavior concerning the prehensile tail, osteological data and kinematic data were collected for Ateles fusciceps and Lagothrix lagothricha. The results demonstrate that Ateles has more numerous and smaller caudal elements, particularly in the proximal tail region. In addition, transverse processes are relatively wider, and sacro-caudal articulation is more acute in Ateles compared to Lagothrix. These differences reflect the larger abductor muscle mass and greater hyperextension in Ateles. In addition, Ateles shows fewer side-to-side movements during tail-assisted brachiation than does Lagothrix. These data support the notion that the prehensile tail represents a critical dynamic element in the tail-assisted brachiation of Ateles, and may be useful in developing inferences concerning behavior in fossil primates.

Animals↗
PubMed2005

Did internal transport, rather than directed locomotion, favor the evolution of bilateral symmetry in animals?

The standard explanation for the origin of bilateral symmetry is that it conferred an advantage over radial symmetry for directed locomotion. However, recent developmental and phylogenetic studies suggest that bilateral symmetry may have evolved in a sessile benthic animal, predating the origin of directed locomotion. An evolutionarily feasible alternative explanation is that bilateral symmetry evolved to improve the efficiency of internal circulation by affecting the compartmentalization of the gut and the location of major ciliary tracts. This functional design principle is illustrated best by the phylum Cnidaria where symmetry varies from radial to tetraradial, biradial and bilateral. In the Cnidaria, bilateral symmetry is manifest most strongly in the internal anatomy and the disposition of ciliary tracts. Furthermore, the bilaterally symmetrical Cnidaria are typically sessile and, in those bilaterally symmetrical cnidarians that undergo directed locomotion, the secondary body axis does not bear a consistent orientation to the direction of locomotion as it typically does in Bilateria. Within the Cnidaria, the hypothesized advantage of bilateral symmetry for internal circulation can be tested by experimental analysis and computer modeling of fluid mechanics. The developmental evolution of symmetry within the Cnidaria can be further explored through comparative gene expression studies among species whose symmetry varies.

Animals↗
PubMed1995

Transplants enhance locomotion in neonatal kittens whose spinal cords are transected: a behavioral and anatomical study.

We have studied the locomotor development of kittens that received complete low thoracic spinal cord transections and embryonic spinal cord transplants as newborns. Embryonic spinal cord (E21-E26) transplanted into the site of a transection integrated well with the host spinal cord and promoted the development of overground locomotion. Spinalized kittens with transplants were first distinguished from spinalized kittens during the 2nd and 3rd postnatal weeks when kittens with transplants positioned their hindlimbs underneath their bodies which promoted support of the hindquarters. By postnatal Week 6, kittens with transplants exhibited overground locomotion characterized by full weight support and moderate balance control. By 20 weeks of age, as many as 96% of the step cycles showed full weight support and as few as 2% of the step cycles were interrupted by a fall. Most kittens also showed coordination between the forelimbs and the hindlimbs. They differed from normal in the precocious onset of reflex stepping and in the less precise interlimb coordination and more precarious balance during overground locomotion. The overground locomotor performance of kittens with transplants greatly exceeded that of spinal kittens without transplants since few spinalized kittens showed any full-weight-supported step cycles and none showed coordination between the forelimbs and the hindlimbs. In the absence of a transplant, no fibers could grow across the lesion site. In the presence of a transplant, fibers grew across the lesion site and established anatomical connectivity with the host. Host segmental systems identified by the presence of calcitonin gene-related peptide- and substance P-immunoreactive fibers were found throughout the transplants. Descending host systems of supraspinal origin were identified by serotonin- and dopamine beta-hydroxylase-immunoreactive fibers throughout the transplants. The growth of supraspinal axons into the transplant, and in one case into the caudal host spinal cord, provided a possible anatomical basis for the development of coordinated overground locomotion.

Age Factors↗
PubMed2002

Both dorsal and ventral spinal cord pathways contribute to overground locomotion in the adult rat.

Identification of long tracts responsible for spontaneous locomotion is critical for spinal cord injury (SCI) repair strategies. We recently demonstrated that extensive demyelination of adult rat thoracic ventral columns, ventromedial, and ventrolateral white matter produces persistent, significant open-field hindlimb locomotor deficits. Locomotor movements resulting from stimulation of the pontomedullary locomotor region are inhibited by dorsolateral funiculus (DLF) lesions suggesting that important pathways for locomotion may also exist in the dorsal white matter. However, dorsal hemisections that interrupt dorsal columns/dorsal corticospinal tract (DC/CST) and DLF pathways do not produce persistent, severe locomotor deficits in the adult rat. We studied the contributions of myelinated tracts in the DLF and DC/CST to overground locomotion following complete conduction blockade of axons in the ventrolateral funiculus (VLF), a region important for locomotor movements and for transcranial magnetic motor-evoked potentials (tcMMEP). Animals received ethidium bromide plus photon irradiation to produce discrete demyelinating lesions sufficient to stop axonal conduction in the VLF, combined VLF + DLF, or combined VLF + DC/CST. Open-field BBB scores and tcMMEPs were studied at 1, 2, 3, and 4 weeks postlesion. VLF lesions resulted in mean BBB scores of 17 at 4 weeks. VLF + DC/CST and VLF + DLF lesions resulted in mean BBB scores of 15.9 and 11.1, respectively. TcMMEPs were absent in all lesion types confirming VLF conduction blockade throughout the study. Our data indicate that significant contributions to locomotion from myelinated pathways within the rat DLF can be revealed when combined with simultaneous compromise of the VLF.

Animals↗
PubMed1997

Ontogeny of locomotion in mountain gorillas and chimpanzees.

The African apes are a group of closely related taxa that differ considerably in body size. In spite of the large body size difference, the African apes are similar in many aspects of their morphology; it has been suggested that most of their differences result from selection for these body size differences (Shea, 1988). The influence of body size on locomotion has been well-documented, but what is less clear, is whether these behavioral differences occur throughout ontogeny because few studies have directly addressed the influence of ontogeny (and changing body size) on locomotion. This study documents the ontogeny of mountain gorilla locomotion and compares it with that of chimpanzees in order to consider how changing body size during ontogeny influences locomotion in the two species. Results indicate that gorilla locomotor development is greatly accelerated compared with chimpanzees, and that much of the interspecific variation in age can be explained by body size. When chimpanzees and gorillas are at similar sizes (although widely disparate ages), they perform very similar locomotor activities. However, it is incorrect to view a gorilla as a faster growing and ultimately larger chimpanzee. Throughout ontogeny, gorillas have broader scapulae and relatively shorter phalanges and metacarpals than chimpanzees (Susman, 1979; Shea, 1981; Jungers & Susman, 1984; Inouye, 1992) which are associated differences in mountain gorilla and chimpanzee suspensory behavior; gorillas never show as high an incidence of suspensory behavior as chimpanzees during ontogeny.

Aging↗
PubMed1990

The study of locomotion by finite state models.

A methodology to derive finite state models of legged locomotion is outlined. Background data for model derivation are joint angle functions and gait diagrams. The method is used to describe the walking of the cat in terms of an abstract automaton. The main features of finite state descriptions of legged locomotion are described. Such models are presenting locomotion invariants of a species in explicit form. It is emphasized that finite state models provide insight into structural features of motor control organization such as decomposition into subsystems, interaction between centralized and decentralized control, and the role of control levels. The finite state model of locomotion can be helpful in suggesting experiments pertinent to the study of motor control and interpretation of experimental results.

Animals↗
PubMed1990

Activity of interneurons within the L4 spinal segment of the cat during brainstem-evoked fictive locomotion.

Extracellular recordings from interneurons located in the L4 spinal segment were made during fictive locomotion produced by electrical stimulation of the mesencephalic locomotor region (MLR) in the paralysed decerebrate cat. Only interneurons within the L4 segment which received group II input from quadriceps, sartorius or the pretibial flexor muscle afferents and which had axonal projections to motor nuclei in L7 were selected for analysis. During the fictive step cycle two thirds of these interneurons fired action potentials during the time of activity in the ipsilateral hindlimb flexor neurograms. These cells were also less responsive to peripheral input during the extension phase of the fictive locomotion cycle. The remaining one third of the interneurons examined were not rhythmically active during locomotion. The possible contributions of the midlumbar interneurons to motoneuron activity during locomotion are discussed.

Action Potentials↗
PubMed1990

Interlimb coordination during fictive locomotion in the thalamic cat.

Efferent discharges in muscle nerves of the four limbs were recorded simultaneously during spontaneous fictive locomotion in thalamic cats with the goal of understanding how the central nervous system controls interlimb coordination during stepping. The onset of the bursts of activity in the nerve of a selected flexor muscle in each limb allowed the temporal and the phase relationships between the fictive step cycle of a pair of limbs to be determined. Our main results are the following: 1) the fictive step cycles of the two forelimbs are always strictly alternated whereas the phasing of the step cycles of either the two hindlimbs or pairs of homolateral or diagonal limbs is more variable; 2) the time interval between the onsets of the flexor bursts of one of the two pairs of diagonal limbs is independent of the step cycle duration; 3) distinct patterns of interlimb coordination exist during fictive locomotion; a small number of patterns of coordination involving all four limbs, which correspond to the walking and the trotting gaits in the intact cat, occur very frequently. The results demonstrate that the central nervous system deprived of phasic afferent inputs from the periphery has the capacity to generate most of the patterns of interlimb coordination which occur during real locomotion. They further support the view that the central pattern of interlimb coordination essentially results from diagonal interaction between a forelimb generator for locomotion and a hindlimb one.

Afferent Pathways↗
PubMed1993

Effects of serotonin on fictive locomotion coordinated by a neural network deprived of NMDA receptor-mediated cellular properties.

The neural network coordinating fictive locomotion in the isolated lamprey spinal cord can be activated by either N-methyl-D-aspartate (NMDA) or kainate/AMPA receptors. Serotonin (5-HT) is known to affect the pattern of fictive locomotion induced by NMDA receptor activation by increasing spike rate within a burst, increasing burst duration, and increasing the intersegmental delay. Two cellular mechanisms contribute to these 5-HT induced effects: The after-hyperpolarization following individual action potentials is reduced and the depolarizing plateau induced by NMDA is prolonged. Both of these serve as important burst-terminating factors in the locomotor network. In order to isolate these two mechanisms, the 5-HT effect on plateau potentials was eliminated by applying 5-HT during fictive locomotion induced by activation of kainate/AMPA receptors. In the absence of NMDA-mediated plateau potentials, the 5-HT-induced increase in burst duration and cycle period was greater than that previously reported during NMDA-induced fictive locomotion. In addition, the prolonged burst period of a single side was subdivided into brief multiple bursts with a shorter cycle period than the control reciprocal burst activity. Intracellular recordings of spinal neurons combined with chloride injection to reverse inhibitory post-synaptic potentials revealed that, in a proportion of these cells, the bursting within a single side may be generated solely or predominantly by phasic excitation.

2-Amino-5-phosphonovalerate↗
PubMed1984

Reversible cooling of the brainstem reveals areas required for mesencephalic locomotor region evoked treadmill locomotion.

The evidence suggests that the mesencephalic locomotor region (MLR) may not be a unitary region since anatomical and functional variations in the descending projections are clearly indicated. Reversible cooling of midline reticular structures can effectively block locomotion evoked by stimulation of lateral MLR (L3.5-4) sites while not significantly affecting the locomotion evoked from more medial MLR (L2-2.5) sites. In contrast, locomotion evoked by stimulation of the medial MLR sites is blocked by cooling of the ipsilateral lateral brainstem region which corresponds to the pontomedullary strip (PLS). Ipsilateral PLS cooling was not effective for blocking lateral MLR evoked locomotion, and contralateral PLS cooling was not effective for blocking either medial or lateral MLR evoked stepping. The evidence indicates that the lateral MLR relays through medial reticular nuclei while the medial MLR sites relay largely through the lateral brainstem structures often referred to as the PLS.

Animals↗
PubMed1997

Modulation of the spinal network for locomotion by substance P in the neonatal rat.

The tachykinin substance P (SP) is present in the ventral and medial area of the lumbar spinal cord. Its localisation suggests that it could modulate the spinal network for locomotion. We have investigated its effects on motor outputs by applying SP, in vitro, to the lumbosacral segments of an isolated spinal cord of new-born rats. SP was applied to the lumbosacral spinal cord either on a quiescent preparation or during episodes of fictive locomotion induced by N-methyl-D,L-aspartate. When applied on quiescent preparations, SP induced a slow rhythmic activity (period >30 s). During fictive locomotion, SP increased both the locomotor frequency and the duration of the bursts of cyclic activity. Furthermore, SP stabilised the locomotor rhythm. These results demonstrate that SP is able to modulate both the "clock" and the pattern generator for locomotion.

Animals↗
PubMed2004

Velocity and curvature in human locomotion along complex curved paths: a comparison with hand movements.

There is extensive experimental evidence linking instantaneous velocity to curvature in drawing and hand-writing movements. The empirical relationship between these characteristics of motion and path is well described by a power law in which the velocity varies in proportion to the one-third power of the radius of curvature. It was recently shown that a similar relationship can be observed during locomotion along curved elliptical paths raising the possibility that these very different motor activities might, at some level, share the same planning strategies. It has, however, been noted that the ellipse is a special case with respect to the one-third power law and therefore these previous results might not provide strong evidence that the one-third power law is a general feature of locomotion around curved paths. For this reason the experimental study of locomotion and its comparison with hand writing is extended here to non-elliptical paths. Subjects walked along predefined curved paths consisting of two complex shapes drawn on the ground: the cloverleaf and the limacon. It was found that the data always supported a close relationship between instantaneous velocity and curvature. For these more complex paths, however, the relationship is shape-dependent--although velocity and curvature can still be linked by a power law, the exponent depends on the geometrical form of the path. The results demonstrate the existence of a close relationship between instantaneous velocity and curvature in locomotion that is more general than the one-third power law. The origins of this relationship and its possible explanation in the mechanical balance of forces and in central planning are discussed.

Adult↗