Exercise enhances axonal growth and functional recovery in the regenerating spinal cord.

We investigated whether enhancing locomotory activity could accelerate the axonal growth underlying the significant recovery of function after a complete spinal transection in the eel, Anguilla. Eels with low spinal transections (at about 60% body length) were kept in holding tanks, where they were inactive, or made to swim continually against a water current at about one body length/s. Their locomotion was periodically assessed by measuring tail beat frequencies at different swimming speeds. Axonal growth was determined from anterograde labeling with 1,1'-diotadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate, inserted postmortem into the spinal cord, just rostral to the transection. Twenty days after surgery, there were significantly more labeled growth cones more than 2 mm caudal from the transection in the exercised fish (74.6+/-2.3%; cf. 34.5+/-1.1%). This difference was still observed at 40 days (57.9+/-1.6% cf. 42.1+/-2% >2 mm), but the regenerated axons were of similar maximum lengths by 120 days (9.8+/-0.3 cf. 7.7+/-2.8 mm). After surgery, each eel undulated its whole body faster at any given swimming speed, thus changing the linear relationship between tail beat frequency and forward speed established before transection. The slope increased by up to 112.5+/-27.4% over the first 8 days post-surgery in inactive animals, while a smaller rise (45.6+/-10.5%) was observed in exercised fish during this period. Thereafter, the slope progressively declined to pre-surgery levels in both groups of animals, but the recovery occurred within 20+/-4 days in exercised eels, as opposed to 40+/-5 days in inactive fish. The locomotory performance of sham-operated fish was unaffected by 10 days of continual locomotion and remained similar to that of naïve eels, pre-transection. These data show that elevated locomotory activity enhances axonal growth and accelerates recovery of locomotory function.

Recovery of locomotion correlated with axonal regeneration after a complete spinal transection in the eel.

This research has examined the relationship between axonal regeneration and the return of normal movement following complete transection of the spinal cord. We made measurements of tail beat frequency and amplitude of the caudal body wave from video recordings of eels (Anguilla anguilla) swimming in a water tunnel at several speeds. Each eel was then anaesthetised and the spinal cord cut caudal to the anus; in some animals the resulting gap was filled with a rubber block. All animals were kept at 25 degrees C for recovery periods ranging from 7 to 128 days, during which their swimming performance was monitored regularly. Each fish was then re-anaesthetised and perfused with fixative and the regrowing descending axons labelled with 1,1'-diotadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate. For all animals and at all speeds after surgery, tail beat frequency increased, while amplitude decreased. In non-blocked animals, an improvement in performance was first seen from 8 days following transection and thereafter tail beat frequency decreased progressively until it had returned to normal after 35 to 45 days, while amplitude remained below baseline until at least 45 days. In these animals, few axonal growth cones had penetrated the caudal stump by 7 days, but some had extended as much as 3 mm by 15 days. Many had reached as far as 6 mm between 25 and 36 days, while by 128 days they had progressed up to 10.5 mm. Contralateral crossing was never observed. Functional recovery was never witnessed in animals in which the cord had been blocked and these eels swam at all times with elevated tail beat frequency and reduced caudal amplitude. No labelled axons could be traced into the caudal spinal cord at any recovery stage in such animals. We conclude that re-innervation of only 1-2 segments caudal to the injury is necessary for functional recovery, although continued axonal growth may be important for the refinement of some aspects of movement.

Levodopa-induced modulation of subthalamic beta oscillations during self-paced movements in patients with Parkinson's disease.

Excessive synchronization of neural activity in the beta frequency band ( approximately 20 Hz) within basal ganglia circuits might contribute to the paucity and slowness of movement in Parkinson's disease (PD). Treatment with dopaminergic drugs reduces the background level of beta frequency band synchronization in the subthalamic nucleus (STN), but has not been shown to increase the proportion of beta activity that is suppressed before voluntary movement in PD. We assessed changes in the event-related desynchronization (ERD) in the beta frequency band of local field potential signals from the region of the STN in 14 patients with PD as they performed self-paced movements of a joystick before and after levodopa administration. The dopamine precursor, levodopa, increased the duration and magnitude of the premovement beta ERD, but did not alter postmovement synchronization in the beta band. Both the latency and magnitude of the beta ERD inversely correlated with the degree of motor impairment. These findings suggest that the beta ERD recorded in the STN area reflects motor-preparative processes that are at least partly dependent on dopaminergic activity within the basal ganglia.

Comparison of two methods of instruction for the prevention of workplace violence.

The purpose of this study was to compare the effect of the poster session format (PSF) with the traditional film discussion format (FDF) on posttest scores using the Violence in the Workplace Knowledge Test (VWKT) for hospital staff. The 25-item VWKT was developed by the authors. Both groups took this test as the pretest and posttest to determine whether there was a difference in ovrall test scores or a difference in score according to type of violence. The control group included a sample of newly hired staff (n = 51) in general hospital orientation who received training via the FDF method and took the posttest after the program. The experimental group included current staff (n = 84) who received training via the PSF. They "walked through" a poster session at their own pace, completing the posttest as they went along. The comparison of mean pretest scores on the VWKT for the two groups was not significantly different. However, the PSF group had greater improvement in test scores than the FDF group. Further analysis determined that the PSF group significantly improved in both types of violence compared to the FDF group. For this study, using an alternative teaching-learning strategy was more effective than the traditional method. Implications for staff development educators include the need to explore different methods of enhancing learning.

Functional recovery and axonal growth following spinal cord transection is accelerated by sustained L-DOPA administration.

The eel, Anguilla anguilla, as with other fish species, recovers well from spinal cord injury. We assessed the quality of locomotion of spinally transected eels from measurements made from video recordings of individuals swimming at different speeds in a water tunnel. Following transection of the spinal cord just caudal to the anus, the animals displayed higher tail beat frequencies and lower tail beat amplitudes than before surgery, owing to the loss of power in this region. Swimming performance then progressively recovered, appearing normal within 1 month of surgery. Eels with similar transections, but given regular, repeated intraperitoneal injections (50 mg/kg) of l-3,4-dihydroxyphenylalanine (L-DOPA) showed an equivalent pattern of decline and recovery that was 10-20 days shorter than that seen in non-treated fish. Axonal growth into the denervated cord, as determined from anterograde labelling experiments, was also more rapid in the drug-treated fish. L-DOPA treatment increased the activity of all fish for up to 18 h, and accelerated the spontaneous movements ('spinal swimming') made by the denervated, caudal portion of the animal that appeared following transection. We suggest that this enhancement of locomotion underlies the accelerated axonal growth and, hence, functional recovery.

Sequence of the gene encoding the 16S rRNA of the beer spoilage organism Megasphaera cerevisiae.

The 16S ribosomal RNA gene from the beer-spoilage organism, Megasphaera cerevisiae was polymerase chain reaction (PCR)-amplified and sequenced. Analysis confirmed the phylogenetic position of M. cerevisiae as a sister taxon of Megasphaera elsdenii, within the obligately anaerobic, Gram-negative cocci. The sequence obtained should facilitate the development of DNA probes for early detection of this spoilage organism.