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Walking smoothly and safely often involves stepping over an obstacle. The purpose of this study was to examine forelimb movements and toe trajectories in stepping over an obstacle during overground locomotion in rats. We performed a kinematic analysis of forelimb movements and measured electromyographic (EMG) activities in the biceps and triceps brachii of the forelimbs. We found that mean toe height just above the obstacle was lower in the leading forelimb than in the trailing forelimb. The toe positions of the leading forelimb at maximal elevation over the obstacle (peak toe position) were closer to the upper edge of the obstacle than those of the trailing forelimb. The linear distance between peak toe position and the upper edge of the obstacle was significantly less in the leading forelimb compared to the trailing forelimb. The peak toe position of the leading forelimb spatially corresponds to the transition point from flexion to extension of the elbow joint. This transition appeared to be controlled mainly by an offset of EMG activity of the elbow flexor, the biceps brachii muscle. In contrast, the trailing forelimb appeared to be controlled by the shoulder and wrist joints. These results suggest that the toe trajectory of the leading forelimb is more accurately regulated than that of the trailing forelimb. In addition, the activities of the elbow flexor may in part contribute to the toe trajectory of the leading forelimb., (Copyright © 2012 Elsevier Ireland Ltd and the Japan Neuroscience Society. All rights reserved.)

Stepping over obstacles to avoid tripping is an essential component in safe and smooth locomotion. Obstacle avoidance during locomotion is completed in several steps during the approach phase toward the obstacle and stepping over the obstacle. The purpose of this study was to investigate gait modification during the approach phase when stepping over obstacles of different heights in rats. In all four limbs, the toe height when the toe was just above the obstacle increased depending on the obstacle height, leaving a safe margin. However, the horizontal distance between toe and obstacle just prior to stepping over was not influenced by obstacle height. In the fore- and hindlimbs that served as trailing limbs, it was found that the stride length and its related swing phase duration in the final step were significantly shorter than those in both the penultimate step and overground locomotion. These results suggest that adjustment of trailing limb in the final step during the approach phase is important in preparation for the stepping movement over an obstacle., (Copyright © 2011 Elsevier Ireland Ltd and the Japan Neuroscience Society. All rights reserved.)

The expression and activity of receptor tyrosine kinases (RTK) at the cell surface can be modulated by several different pathways including the proteolytic release of the extracellular domain as a soluble receptor. We investigated the regulation of tie receptor expression, an orphan RTK restricted to cells of hematopoietic and endothelial lineages, on primary human endothelial cells and a stably transfected Chinese hamster ovary (CHO) cell line. Tie was expressed in cells as a doublet of 135 and 125 kD; the 135-kD band represented mature cell surface receptor containing sialic acid and N-linked oligosaccharide residues, whereas the 125-kD band represented an intracellular pool of immature receptor. Phorbol 12-myristate 13-acetate (PMA) had dramatic effects on tie expression at the cell surface. Within 15 minutes of PMA treatment, the 135-kD band disappeared from the cell surface and was accompanied by the appearance of a 100-kD band in cell supernatants. The 100-kD band continued to accumulate in the media throughout the duration of PMA treatment during which mature tie receptor was undetectable on the cell surface by fluorescence-activated cell sorting (FACS) or in cell lysates by immunoblot analysis. Using specific antibodies, this 100-kD species was shown to be a soluble form of the tie receptor containing the extracellular domain. PMA-dependent release of soluble tie was mediated through the activation of protein kinase C (PKC); soluble tie was not released in the presence of PKC inhibitors, an inactive PMA analog, or following the downregulation of PKC through chronic PMA treatment. These results indicate that tie receptor expression on endothelial cells is regulated by the release of a soluble extracellular fragment following activation of PKC. Parallel pathways regulating c-kit, tumor necrosis factor (TNF), and colony-stimulating factor (CSF) receptor expression suggest that the release of extracellular receptor fragments represents an alternative mechanism through which cells modulate responses to growth factors and cytokines.

The growth and development of hair follicles is influenced by a number of different growth factors and cytokines, particularly members of the fibroblast growth factor (FGF) family. Keratinocyte growth factor (KGF or FGF-7) is a recently identified 28-kd member of the FGF family that induces proliferation of a wide variety of epithelial cells, including keratinocytes within the epidermis and dermal adnexa. Because KGF induces marked proliferation of keratinocytes, and both KGF and KGF receptor (KGFR) mRNA are expressed at high levels in skin, we sought to localize KGF and KGFR in skin by in situ hybridization. KGFR mRNA was relatively strongly expressed by keratinocytes in the basilar epidermis as well as throughout developing hair follicles of rat embryos and neonates. KGF mRNA was expressed at lower levels than was KGFR but could be localized to follicular dermal papillae in rat embryos and neonates. These results prompted us to investigate the effects of KGF on hair follicles in two distinct murine models of alopecia. In the first model, recombinant KGF (rKGF) induced dose-dependent hair growth over most of the body in nu/nu athymic nude mice when administered intraperitoneally or subcutaneously over 17 to 18 days. When administered subcutaneously, rKGF induced the most extensive hair growth at the sites of injection. Histologically, rKGF induced marked follicular and sebaceous gland hypertrophy, a normalization of the nu/nu follicular keratinization defect, and an increase in follicular keratinocyte proliferation as assessed by bromodeoxyuridine labeling. In the second model, a neonatal rat model of cytosine arabinoside chemotherapy-induced alopecia in which interleukin-1, epidermal growth factor, and acidic FGF have all demonstrated some degree of alopecia cytoprotection, rKGF induced a dose-dependent cytoprotective effect, abrogating as much as 50% of the alopecia in this model when administered beginning 1 day before the onset of chemotherapy. Taken together, these data suggest that KGF is an important endogenous mediator of normal hair follicle growth, development, and differentiation.

We recorded spike potentials from Purkinje cells in the lateral vermis of lobule V in cat cerebellum, and found significant enhancement in climbing fiber discharges during perturbed locomotion. Five adult cats were decerebrated at a precollicular level, and 4-5 days thereafter, they were mounted on a treadmill. During stable locomotion at 36 cm/s belt velocity, climbing fiber responses were slightly modulated with a weak increment at the swing phase of the ipsilateral forelimb. When the left contralateral forelimb alone was suddenly imposed with a faster belt velocity of 61 cm/s, the occurrence of the climbing fiber discharges was significantly enhanced during the late swing phase of the ipsilateral forelimb. This observation is in accordance with the general notion that climbing fiber responses represent error signals in control of movements.

Adaptive interlimb coordination was studied during perturbed locomotion in experimental chronically decerebrate cats. Perturbations were applied to the stance phases of the left forelimb using a newly developed treadmill which consisted of three compartments, one each for the left forelimb, the left hindlimb and both right limbs. During the perturbed locomotion, the treadmill belt for the left forelimb was driven at about twice the speed for the other limbs. During the first 1-50 perturbed steps, the step cycles of both forelimbs showed marked fluctuations; thereafter, the animals achieved stable locomotion by slightly shortening step cycle durations, and also by adjusting durations of bisupport phases asymmetrically in the left and right forelimbs. The present method provides a new test paradigm for adaptive interlimb coordination in locomotion, which will be useful in studying neural mechanisms of motor learning involving cerebellar synaptic plasticity.

The dorsal light response (DLR) to the continuously rotating light source was investigated in goldfish that had lesioned the valvula cerebelli. The body inclination was observed and analyzed for every 10 degrees of light rotation. The effects of selective lesions of the medial and lateral valvula cerebelli on the DLR were compared. After the lesion of the medial valvula cerebelli, the fish responded to the rotating light in the similar pattern to that seen preoperatively. However, after the unilateral lesion of the lateral valvula cerebelli, the fish did not respond to light from the side contralateral to the lesion, as if the fish had been unilaterally blindfolded. The lesion induced by kainic acid of the rostral and caudal part of the lateral valvula cerebelli differently influenced on the DLR. The DLR was impaired only after the caudal part of the lateral valvula cerebelli was lesioned by kainic acid. These findings suggest that the lateral valvula cerebelli in goldfish mediate the induction of the visually guided aspects of the DLR.

The afferent connections of the lateral lobe of the valvula cerebelli in goldfish were investigated by retrograde labeling with horseradish peroxidase (HRP). Retrogradely labeled neurons were observed ipsilaterally in the lateral nucleus of the valvula and contralaterally in the inferior olivary nucleus after HRP injection into all parts of the lateral valvula. The valvulopetal projections from these nuclei were topographically arranged. After HRP injection confined to the rostral half of the lateral valvula, labeled neurons were also found ipsilaterally in the octavolateral and trigeminal cell groups: the eminentia granularis, the medial nucleus of the octavolateralis column, and the isthmic primary sensory trigeminal nucleus. HRP injection confined to the caudal half of the lateral valvula resulted in retrograde labeling of the following vision-related cell groups; the central pretectal nucleus, nucleus paracommissuralis, and the nucleus isthmi. However, the octavolateral and trigeminal cell groups did not project to the caudal half of the lateral valvula. These data provide insight into central nervous integration of visual and vestibular information, and help reveal the mechanism of the dorsal light response (DLR). Bilateral lesions of either the valvula cerebelli or pretectal area completely abolish this visually-guided response, but lesions of the optic tectum have no such effect. The pretectal nuclei (central pretectal nucleus, nucleus paracommissuralis) project to the lateral valvula directly, not via the optic tectum. These direct projections from the pretectal accessory optic nuclei to the lateral valvula may control the DLR. On the other hand, the lateral valvula receives vestibular and lateral line inputs indirectly, via the eminentia granularis and the medial nucleus of the octavolateralis column, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Recombinant platelet-derived growth factor (BB homodimer, rPDGF-BB), transforming growth factor beta 1 (rTGF-beta 1), and basic fibroblast growth factor (rbFGF) can accelerate healing of soft tissues. However, little information is available characterizing the components of wound matrix induced by these growth factors and the molecular mechanisms underlying accelerated repair and wound maturation. In this study, the composition, quantity, and rate of extracellular matrix deposition within growth factor-treated lapine ear excisional wounds were analyzed at different stages of healing using specific histochemical and immunohistochemical stains, coupled with image analysis techniques. Single application of optimal concentrations of each growth factor accelerated normal healing by 30% (P less than 0.0003); rPDGF-BB markedly augmented early glycosaminoglycan (GAG) and fibronectin deposition, but induced significantly greater levels of collagen later in the repair process, compared with untreated wounds rTGF-beta 1 treatment led to rapidly enhanced collagen synthesis and maturation, without increased GAG deposition. In contrast, rbFGF treatment induced a predominantly angiogenic response in wounds, with a marked increase in endothelia and neovessels (P less than 0.0001), and increased wound collagenolytic activity (P less than 0.03). rbFGF-treated wounds did not evolve into collagen-containing scars and continued to accumulate only provisional matrix well past wound closure. These results provide new evidence that growth factors influence wound repair via different mechanisms: 1) rPDGF-BB accelerates deposition of provisional wound matrix; 2) rTGF-beta 1 accelerates deposition and maturation of collagen; and 3) rbFGF induces a profound monocellular angiogenic response which may lead to a marked delay in wound maturation, and the possible loss of the normal signal(s) required to stop repair. These results suggest that specific growth factors may selectively regulate components of the repair response by differing mechanisms, offering the potential for targeted therapeutic intervention.

As the second telescience testbed experiment we were examined sophisticated processes of biomedical experiment, such as an implantation of a transmitter into the hamster's abdominal cavity, non-stressful blood sampling, large amount of blood collection, muscle extirpation and biopsy from the hamsters on February 6-8, 1990. To make clear the differences between successful results obtained by an experienced hand and by a non-experienced one, three operators were selected for three successive experimental days; an engineer who had never experienced any biological experiment, a non-biology student, who experienced on biological experiments, and a veterinary surgeon. Surgical procedures need much experiences on maneuvering and understanding of theory to shorten the elapse time. Especially for a non-experienced hand, graphic instructions were much helpful to understand and to maneuver the procedures. Continuous recordings of ECG from a operator and PIs were of an advantage to grasp an extent of the mental strain, which was compared with their reports requested after end of each experimental day. The mental strain was not related to degrees of scientific achievement, but showed faithfully difficulty of each experimental procedure. Training effects on PIs in successive experimental days were found in their instructions for the operator to let understand the procedures.

Human follicular fluid was found to induce the formation of new blood vessels on the chick chorioallantoic membrane 3 to 5 days after implantation. To characterize this response more fully, the effects of human follicular fluid on a continuous line of bovine aortic arch endothelial cells were studied. Human follicular fluid showed strong mitogenic activity toward endothelial cells, ranging from a threefold increase in thymidine incorporation at a dilution of 1:10 to a 1.4-fold increase at a dilution of 1:3200. Endothelial cells also exhibited a directional migration (chemotaxis) toward human follicular fluid. A 1:10 dilution of human follicular fluid induced a 6.8-fold increase in directional cellular migration through membranes with 8 microns pores, and a 1:800 dilution induced a 1.8-fold increase in migration. Endothelial cells responding to gradients of human follicular fluid also demonstrated a marked change in morphologic structure when compared with control cells. Human plasma and fibrinogen were angiogenic and chemotactic (but not mitogenic) toward endothelial cells, which suggested that fibrinogen may account for at least part of the angiogenic activity of human follicular fluid. These results indicate that human follicular fluid is strongly angiogenic and that this biologic activity can be associated with effects directly on endothelial cells in vitro.