Overground locomotion in intact rats: interlimb coordination, support patterns and support phases duration.
(25/2687)
The interlimb coordination during overground locomotion was analysed in intact rats, using the method of contact electrodes (Gorska et al. 1998). It was found that in animals moving with a speed ranging from 10 to 78 cm/s (step cycles 685 to 215 ms, respectively) the interlimb coordination was characterized by homologous phase shifts close to 0.5 and much shorter diagonal than lateral phase shifts. These features corresponded to symmetrical gait with diagonal sequence and diagonal couplets (Hildebrandt 1976). Shortening the step cycle changed the gait from a walking trot (duty factor > 0.5) into a running trot (duty factor < 0.5). Correspondingly, the support patterns in the four-legged step cycles, i.e., the sequence of phases of support on various limbs changed: the support on diagonal limbs persisted but the three-limb support was replaced by one-limb support and the support on homolateral limbs by phases of flight. For each phase of support the relationship between its absolute and relative durations and the step cycle duration is being described. The paper explains the variability of support patterns described in the literature. The picture of locomotion obtained in intact rats will be used as a template for studying locomotor control deficits after CNS lesions. (+info)
The diving physiology of bottlenose dolphins (Tursiops truncatus). II. Biomechanics and changes in buoyancy at depth.
(26/2687)
During diving, marine mammals must balance the conservation of limited oxygen reserves with the metabolic costs of swimming exercise. As a result, energetically efficient modes of locomotion provide an advantage during periods of submergence and will presumably increase in importance as the animals perform progressively longer dives. To determine the effect of a limited oxygen supply on locomotor performance, we compared the kinematics and behavior of swimming and diving bottlenose dolphins. Adult bottlenose dolphins (Tursiops truncatus) were trained to swim horizontally near the water surface or submerged at 5 m and to dive to depths ranging from 12 to 112 m. Swimming kinematics (preferred swimming mode, stroke frequency and duration of glides) were monitored using submersible video cameras (Sony Hi-8) held by SCUBA divers or attached to a pack on the dorsal fin of the animal. Drag and buoyant forces were calculated from patterns of deceleration for horizontally swimming and vertically diving animals. The results showed that dolphins used a variety of swimming gaits that correlated with acceleration. The percentage of time spent gliding during the descent phase of dives increased with depth. Glide distances ranged from 7.1+/-1.9 m for 16 m dives to 43.6+/-7.0 m (means +/- s.e.m.) for 100 m dives. These gliding patterns were attributed to changes in buoyancy associated with lung compression at depth. By incorporating prolonged glide periods, the bottlenose dolphin realized a theoretical 10-21 % energetic savings in the cost of a 100 m dive in comparison with dives based on neutral buoyancy models. Thus, modifying locomotor patterns to account for physical changes with depth appears to be one mechanism that enables diving mammals with limited oxygen stores to extend the duration of a dive. (+info)
Seven year follow up of children presenting to the accident and emergency department with irritable hip.
(27/2687)
OBJECTIVE: To assess an established protocol for managing children with irritable hip in the accident and emergency department. METHODS: Retrospective seven year follow up of all children managed under an established hip pain protocol. The main outcome measure was of failure of the protocol to identify serious pathology. RESULTS: A total of 103 children met the criteria for assessment using the protocol. Sixty were allowed home, and outpatient follow up arranged. All of these children except one were diagnosed as having transient synovitis. This child had Perthes' disease and was diagnosed at first presentation. Forty three children were admitted, with eight subsequently having a diagnosis other than transient synovitis of the hip. It was possible to review 80 children seven years later. Of these children no long term problems were encountered. CONCLUSION: The protocol used in the department for children with irritable hip is successful in identifying those children with transient synovitis of the hip, or other benign causes, and therefore not requiring hospital admission. Long term follow up showed that no serious pathology was missed. (+info)
Toxicological studies on pipemidic acid. V. Effect on diarthrodial joints of experimental animals.
(28/2687)
Pipemidic acid (PPA) orally given in a dose of 100 mg/kg/day or more was found to cause lame gait in immature beagle dogs of about 3 months old. Their diarthrodial joints were abnormal with increased synovial fluid and blister formation under the outer layer of the articular cartilage. However, such an abnormality was not found in dogs younger than 2 weeks or older than 12 months. The blisters were formed at the joint areas bearing the body weight at a time when PPA was considered to be present there. Nalidixic and piromidic acids, structural analogues of PPA, also caused abnormality similar to PPA. The severity of the arthropathy was slight with piromidic acid as compared with PPA and nalidixic acid. The gait abnormality was almost disappeared spontaneously even if medication was continued. The incidence of the arthropathy was not or rarely observed in any young rats, rabbits and monkeys. (+info)
Urinary function in elderly people with and without leukoaraiosis: relation to cognitive and gait function.
(29/2687)
OBJECTIVES: To investigate urinary function in the elderly with and without white matter lesion (leukoaraiosis) in relation to cognitive and gait function. METHODS: Sixty three subjects were examined, with mean age 73 (range 62 to 86 years). Subjects with brainstem stroke or with large hemispheric lesions were excluded. Spin echo 1.5 T MRI images were graded from 0 to 4 for severity of white matter lesions. Urinary function was assessed by detailed questionnaire and urodynamic studies were performed in 33 of the subjects, including measurement of postmicturition residuals, water cystometry, and sphincter EMG. A mini mental state examination (MMSE) and examination of gait was also performed and compared with urinary function. RESULTS: Urodynamic studies showed subjects with grade 1-4 white matter lesions to have detrusor hyperreflexia more commonly (82%) than those with grade 0 white matter lesions (9%) (p<0.05), indicating that leukoaraiosis was a factor associated with geriatric urinary dysfunction. Postmicturition residuals, low compliance, detrusor-sphincter dyssynergia, and uninhibited sphincter relaxation were also more common in grade 1-4 than in grade 0 white matter lesions, though the difference was not significant. In grade 1 white matter lesions urinary dysfunction (urge urinary incontinence) was more common than cognitive (MMSE<19) (p<0.05) and gait disorders (slowness, short step/festination, and loss of postural reflex) (p<0. 05), which increased together with the grade of white matter lesions (p<0.05). CONCLUSIONS: Urinary dysfunction is common and probably the early sign in elderly people with leukoaraiosis on MRI. (+info)
A densitometric analysis of the human first metatarsal bone.
(30/2687)
Bone responds to the stresses placed on it by remodeling its structure, which includes shape, trabecular distribution and density distribution. We studied 49 pairs of cadaveric human 1st metatarsal bones in an attempt to establish the pattern of density distribution and to correlate it with the biomechanical function of the bone. We found that the head is denser than the base, the dorsal portion of the whole metatarsal is denser than the plantar portion and the lateral portion of the whole metatarsal is denser than the medial aspect. The same pattern of density with respect to dorsal vs plantar and lateral vs medial was also seen in the head when it was examined alone. When we compared the 4 portions of the head with the same portion of the metatarsal as a whole we found that only the medial portion of the head was less dense than its respective portion of the whole metatarsal. All of these patterns of density distribution are consistent with respect to age, sex and laterality. We have also hypothesised as to the relationship between density distribution seen both in the whole metatarsal and in the metatarsal head and their biomechanical function in the gait cycle. (+info)
Prosthetic reconstruction for tumours of the distal tibia and fibula.
(31/2687)
We have carried out prosthetic reconstruction in six patients with malignant or aggressively benign bone tumours of the distal tibia or fibula. The diagnoses were osteosarcoma in four patients, parosteal osteosarcoma in one and recurrent giant-cell tumour in one. Five tumours were in the distal tibia and one in the distal fibula. The mean duration of follow-up was 5.3 years (2.0 to 7.1). Reconstruction was achieved using custom-made, hinged prostheses which replaced the distal tibia and the ankle. The mean range of ankle movement after operation was 31 degrees and the joints were stable. The average functional score according to the system of the International Society of Limb Salvage was 24.2 and five of the patients had a good outcome. Complications occurred in two with wound infection and talar collapse. All patients were free from neoplastic disease at the latest follow-up. Prosthetic reconstruction may be used for the treatment of malignant tumours of the distal tibia and fibula in selected patients. (+info)
Serial force plate analyses of dogs with unilateral knee instability, with or without interruption of the sensory input from the ipsilateral limb.
(32/2687)
OBJECTIVE AND DESIGN: We characterized the mean peak vertical forces (MFz) in five groups of dogs which underwent transection of the left anterior cruciate ligament (ACLT) or sham ACLT and ipsilateral dorsal root ganglionectomy or sham-ganglionectomy, and the relationship of these forces to the severity of osteoarthritis (previously reported) 72 weeks after arthrotomy. Group I (N=7) underwent ACLT; Group II (N=8) underwent ACLT followed 52 weeks later by ganglionectomy; Group III (N=7) underwent ganglionectomy followed 2 weeks later by ACLT; Group IV (N=7) underwent sham-ganglionectomy followed 2 weeks later by ACLT; Group V (N=8) underwent ganglionectomy followed 2 weeks later by sham-ACLT. The dogs were evaluated 2, 6, 12, 24, 52 and 72 weeks after arthrotomy. RESULTS: From 6 weeks after arthrotomy until death, the left hindlimb MFz in Group V was significantly greater (P< 0.05) than that in the other four groups. The MFz of all groups which underwent ACLT decreased after arthrotomy. While the MFz of Group III (very severe OA) was about 10-20% greater than that of Groups I, II and IV (mild OA) 6 and 12 weeks after ACLT, and generally about 5-10% greater subsequently, this difference was not statistically significant. The MFz of Group II returned to pre-ganglionectomy levels, rather than to baseline levels, following ganglionectomy. CONCLUSIONS: (1) since the ipsilateral limb of dogs with ganglionectomy+sham ACLT bore normal amounts of weight throughout most of the postsurgical period, and its knee did not develop OA, one cannot argue that the knee was protected from OA because the limb was not used; (2) the fact that the MFz of dogs which underwent ACLT+ganglionectomy returned to pre-ganglionectomy levels, rather than baseline, is consistent with the hypothesis that the unstable joint was protected from accelerated breakdown by a central nervous system that was reprogrammed by sensation from the unstable limb; (3) the slightly-but consistently-greater MFz of dogs which underwent ganglionectomy+ ACLT may contribute to the acceleration of OA in this model. (+info)