Teaching becomes learning. Our lived experience.

Two teachers involved in the curriculum transformation process describe how they created and implemented a new learning environment with first-year nursing students in a basic baccalaureate nursing program. The authors have taught the introductory nursing course within this paradigm shift and describe the process of developing ends-in-view and relevant student experiences. They also reflect on the new meaning of the teaching-learning process within this paradigm.

The growth of PC12 neurites is biased towards the anode of an applied electrical field.

We have exposed cultures of PC12 cells to uniform DC electric fields following the addition of NGF. The success of these experiments relied upon the design of new chambers enabling fields to be applied to mammalian cell cultures. After 48 h of field application, the distribution of neurite outgrowths was biased towards the anode. More neurites faced the anode than would be expected if growth was uniform. The magnitude of this bias was strongly correlated with field strength, with a threshold value of about 1 mV/mm. At field strengths above 30 mV/mm, the neurites growing towards the cathode were shorter than those growing towards the anode or perpendicular to the field. This response was not correlated with field strength. This report confirms that mammalian neurons respond to electrical fields and supports the notion that neurites are influenced by endogenous electrical fields during development. As far as we are aware, this is the only report that documents a response towards the anode.

Regeneration of rat sciatic nerves in silicone tubes: characterization of the response to low intensity d.c. stimulation.

Endogenous d.c. electric fields have been postulated to play a role in normal development and repair functions of a variety of living systems. The corollary hypothesis, that exogenous electric fields can alter development and repair mechanisms, has led to the use of d.c. electric fields as a means to enhance mammalian peripheral nerve regeneration. This study investigates the response of transected rat sciatic nerves within silicone tubes to low intensity d.c. stimulation. In 40 rats, the right sciatic nerves were transected and sutured into silicone tubes, leaving a 5.0 mm gap between the stumps. The nerves were either treated with 10 microA d.c., with the cathode at the midpoint of the tube and the anode distant, or received no exogenous current. Three weeks later, transverse sections from the center of the tissue bridging the two segments were analysed by sampling approximately 12% of the cross sectional area, using x 1000 magnification on the light microscope. All non-stimulated (control) nerves showed regeneration of myelinated axons at the center of the bridge, while only 35% of the nerves stimulated with 10 microA had such a response. Of the nerves with regeneration of myelinated axons at the center of the tube, the control nerves had significantly more myelinated axons (P = 0.0028) than treated nerves. Stimulated nerves showed bizarre regeneration responses, including formation of multiloculated cysts and neuroma-like formations. In control nerves there was a gradual tapering of axon number from proximal to distal in the regeneration bridge, while in the stimulated nerves there was a sharp decrease in the number of axons proximal to the cathode. We hypothesize that this effect is due to the accumulation of electrolysis products at the cathode, which inhibit regeneration through this region. Regeneration of transected rat sciatic nerves is not enhanced by electric currents applied in this manner. Previous work interpreted the increased number of axonal cross-sections in the tube as an increase in the absolute number of regenerating fibers. Our data suggest that the increased number of axonal cross-sections is due to neuroma formation, probably in response to the accumulation of electrolysis products at the cathode. This work brings into question claims of an enhancement of peripheral nerve regeneration by applied electric fields.

Effects of applied electric fields on clinical cases of complete paraplegia in dogs.

A clinical trial of applied, slowly oscillating, weak electric fields was performed in dogs with naturally occurring spinal cord injuries due to intervertebral disc herniation. Criteria for admission to the study were: complete paraplegia, defined by neurological examination and electrophysiological testing; intact segmental reflexes; radiologic and myelographic evidence of spinal cord compression due to disc herniation and a focal lesion, without appreciable rostrocaudal spread of necrosis; weight less than 16 kg; onset of paralysis less than 1 month before surgery. The injured cord was exposed by laminectomy, and decompressed by aspiration of disc material. Active (n = 13) or sham (n = 11) stimulators were implanted subcutaneously, with platinum/iridium electrodes sutured to muscle several millimeters above the cord surface, at either end of the laminectomy site. Active stimulators delivered 200 µA of direct current, switching polarity every 15 min, for 3, 6, or 15 weeks. Neurological and electrophysiological examinations were repeated approximately 6 weeks and 6 months after implantation. Few complications were noted. None were attributable to current application. The group of dogs with active stimulators showed greater improvement in function than the group with sham implants, with a trend towards greater recovery in all neurological measures, and evoked potentials. The combined neurological score derived from these separate tests was significantly different from controls at 6 weeks and 6 months (P < 0.05). Application of slowly oscillating electric fields thus appears to be beneficial in the treatment of paraplegia in dogs.

The lack of an effect of applied d.c. electric fields on peripheral nerve regeneration in the guinea pig.

This study was undertaken to provide evidence of enhanced regeneration of mammalian peripheral nerves in response to applied d.c. electric fields. Peroneal nerves of adult guinea-pigs were crushed or transected and anastomosed. Constant current d.c. stimulators (20 microA) were implanted in the flank with platinum/iridium electrodes routed to the ankles. Animals with crush lesions were tested for toe spreading ability from the 14th to the 23rd day following the lesion. Animals with transection lesions were allowed to recover for 40 days and isometric force measurements of toe abduction and foot flexion were made. Both myelinated and unmyelinated fiber densities were determined. There proved to be no difference between legs treated with an anode, a cathode, or a sham electrode as evaluated by: the time to return of the toe spreading reflex, the isometric force of either twitches or tonic contractions, the latency between stimulation and contraction, or the number or density of either myelinated or unmyelinated fibers. These negative results are at variance with other studies that have reported beneficial effects of d.c. electric fields on peripheral nerve regeneration. The stimulation and analysis techniques used in this study were well within the variety of protocols that have yielded reports of highly significant positive effects with smaller numbers of animals than used in this study. The conclusion is that either there is a subtle but highly specific and critical difference between the present protocol and others, or the other studies need to be reevaluated. In either case, it seems that the ability of applied d.c. fields to enhance peripheral nerve regeneration in vivo remains open to question.

Cutaneus trunci muscle reflex of the guinea pig.

The cutaneus trunci muscle reflex in guinea pigs was studied with a combination of video analysis, electromyography, lesioning, and light microscopy. The muscle forms a bilateral, subdermal sheet over much of the trunk. Local contractions of the dorsal part of the muscle are produced in response to brief tactile or electrical stimulation of the skin and consist of a twitch centered 1-2 cm rostral of the stimulus site. The reflex receptive field covers most of the thoracic and lumbar dorsal surface. The sensory information is carried via segmental dorsal cutaneous nerves. Receptive fields of adjacent nerves overlap and form rectangular areas perpendicular to the midline, at thoracic levels. Motor innervation projects through the lateral thoracic nerves of the brachial plexus. The motoneurons are located near the cervical thoracic junction (C7-T1). Lesions of the lower thoracic cord indicate that ascending sensory information is carried to the motor nuclei via the ventral half of the lateral funiculus. This pathway conveys information primarily from ipsilateral skin. There is a weaker input from contralateral skin, crossing at segmental levels. Electromyographic responses to brief electrical stimulation of lower thoracic skin occur usually as 10-12 msec bursts at latencies of 10-20 msec, and do not readily habituate or fatigue at stimulus frequencies below 10 Hz. The reflex persists under light pentobarbital anesthesia. This combination of characteristics makes the reflex useful for a variety of physiological and pathophysiological studies.

Functional recovery after spinal cord hemisection in guinea pigs: the effects of applied electric fields.

Right lateral hemisection of the lower thoracic spinal cord was performed in 216 adult guinea pigs. Animals that proved suitable for the study were divided into one control and two experimental groups. Experimental animals were implanted with intraperitoneal stimulators delivering regulated current of 35 or 50 microA through electrodes placed 1 cm rostral and caudal of the hemisection. The cathode was cranial to the lesion in one group (n = 67) and caudal in the other (n = 33). Control animals (n = 62) were implanted with sham stimulators and electrodes delivering no current. The functional status of the animals was measured by tactile stimulation of the back skin to elicit the cutaneus trunci muscle reflex, and by the vestibulospinal free-fall response. The cutaneous response ipsilateral and caudal to the lesion was lost following hemisection and did not recover in any of the control animals or in animals with cathode caudal to the lesion. Recovery of the response was found in 9 of 67 animals in the cathode rostral group, between 56 and 139 days after injury. Toe spreading recovered spontaneously in 80-90% of animals in all groups. Of the possible mechanisms of skin reflex recovery, most current evidence points to regrowth of ascending nerve fibers in the lateral funiculus of the spinal cord local to the lesion.

Behavioral recovery induced by applied electric fields after spinal cord hemisection in guinea pig.

Applied electric fields were used to promote axonal regeneration in spinal cords of adult guinea pigs. A propriospinal intersegmental reflex (the cutaneous trunci muscle reflex) was used to test lateral tract function after hemisection of the thoracic spinal cord. An electrical field (200 microvolts per millimeter, cathode rostral) applied across the lesion led to functional recovery of the cutaneous trunci muscle reflex in 25 percent of experimental animals, whereas the functional deficit remained in control animals, which were implanted with inactive stimulators.

Stump currents in regenerating salamanders and newts.

We report here that a variety of salamanders and newts from differing habitats all drive a steady ionic electric current out of the forelimb stump tip after forelimb amputation. Several hours after amputation the density of this stump current ranges from about 10 to 100 microA/cm2 in most species, and declines with time. In most cases, the magnitude of the stump current is dependent on the concentration of Na+ in the external medium (an artificial pondwater), suggesting that the well-known Na+ -dependent transcutaneous voltage described in amphibia (particularly frogs) is the EMF for this stump current. These measurements add to those previously reported for the North American red spotted newt (Notophthalmus viridescens), and suggest that electrical changes following amputation of urodele limbs are widespread among members of this group.

Admission predictors for pre-physical therapy majors.

This study was designed to determine whether a criterion exists for advisors to give students some indication early in their academic careers of their ultimate chances for admission to professional schools of physical therapy. Biographical questionnaires completed by pre-physical therapy students at Northern Illinois University provided materials for a descriptive study. Data obtained from files of successful and unsuccessful student applicants provided variables for a multiple-regression analysis. Results indicate that biographical data cannot be used to differentiate successful from unsuccessful applicants to professional programs. The only statistically significant variable tested that might be considered in advising students whether to remain in the major is their grade-point average at the end of the freshman year.