Long-term effects of methylphenidate transdermal delivery system treatment of ADHD on growth.

OBJECTIVE: To examine the long-term effects of the methylphenidate transdermal system (MTS) on the growth of children being treated for attention-deficit/hyperactivity disorder. METHOD: Height, weight, and body mass index (BMI) were measured in 127 children ages 6 to 12 at longitudinal assessments for up to 36 months of treatment with MTS. These data were compared with norms provided by the Centers for Disease Control and Prevention. RESULTS: MTS treatment was associated with small but significant delays in growth for height, weight, and BMI. The latter two indices were affected in a dose-dependent manner. Children who had not received prior stimulant therapy and children who entered the study with above-average height, weight, and BMI were most likely to experience growth deficits during the trial. Effects on all parameters of growth were most apparent during the first year of treatment, and attenuated over time. CONCLUSIONS: Consistent with prior studies of methylphenidate, our results suggest that treatment with MTS can lead to reductions in expected height, weight, and BMI that show some attenuation over the course of treatment. Growth of patients with attention-deficit/hyperactivity disorder treated with MTS should be closely monitored, but in this study, deficits in growth in relation to MTS treatment were not a significant clinical concern for most children.

Spinal projection to the dorsolateral nucleus of the caudal basilar pons in the cat.

In the cat, a spinal projection to a restricted area of the basilar pontine grey has been revealed with use of anterograde degeneration technique (Fink-Heimer). The area was ipsilateral to the spinal lesion, restricted to the far caudal limit of the pons, and included the dorsal and the dorsolateral subdivisions of the pontine nuclei (PN). Comparisons following high cervical, midthoracic and upper lumbar spinal lesions did not reveal any somatotopic organization. Only a few spinopontine fibers had origins below segmental level L4. Lesions of various quadrants of the cord indicated that the spinopontine fibers ascended through the dorsolateral funiculus, and not through either the dorsal or the ventral funiculi. Comparison with the degeneration effects of cerebral cortical lesions showed that the spinal projection to the PN overlapped to some extent with the projection from the first sensorimotor and second somatosensory cortices. In the rat no comparable spinopontine projection was found. It is suggested that the spinopontine pathway might forward information to the cerebellum from visceral sensory receptors or perhaps from pools of spinal interneurons.

Effects of age at cordotomy and subsequent exercise on contraction times of motor units in the cat.

The contraction times (CTs) of functionally isolated motor units (MUs) in the soleus (SOL) and medial gastrocnemius (MG) muscles were determined in cats that had been spinalized at ages 2 (n = 15) or 12 (n = 9) wk and then either subjected to exercise on a treadmill or simply given manipulative care of the hindlimbs. The MUs were tested approximately 12 wk after the low-thoracic cordotomy, and comparisons were made with data from control animals. The CT of 50.9 ms obtained for SOL units (n = 163) in the spinal cats was 22% shorter than the mean of 65.0 ms for MUs (n = 57) from control cats (n = 4). Contrary to expectation, the CT in animals spinalized at 12 wk was significantly shorter than that in the 2-wk group. The CT for MG units (n = 105) in spinal cats was also significantly shorter (11%) than that in controls cats (n = 66, 6 cats), and those units identified by their high fatigue index as being of slow or fatigue-resistant type had a shorter CT than units with a low index. No distinction in CT of exercised and nonexercised groups was detected for either muscle. These findings are discussed in relation to the bearing influences of supraspinal and segmental origin have on CT duration in SOL and MG muscles during growth of the kitten. A slight, significant decrease (6%) in the fatigue index of SOL MUs (n = 144) was detected, but the values remained high (mean 0.87).

Comparison of contraction times of a muscle and its motor units.

The twitch contraction time (CT) for each of 13 soleus (SOL) and 13 medial gastrocnemius (MG) muscles was compared with the mean CT from a sample of its motor units (MUs; 356 total) to see if the CT of a whole muscle when tested at its optimal length (Lo) differed systematically from that of its MUs tested at their individual Lo's. The CTs of the whole muscle were significantly longer in the ratio of 1.13. This is consistent with a hypothesis that electrical-field effects result in a more protracted contraction of the individual muscle fiber.

Effects of high-frequency (500-1,000 Hz), indirect stimulation on slow and fast muscle relevant to orthotic applications.

The effects of indirect stimulation at 500-1,000 Hz on force production by the cat's slow-fibered soleus and mixed-fiber medial gastrocnemius (MG) muscles were compared for their relevance to the use of such "high-frequency" stimulation to modulate spasticity or the induced contraction of a centrally paralyzed muscle. Severe loss in force was seen in both muscles, and slow (S) motor units (MUs) within the MG showed about the same susceptibility as fast (FF) units. Both muscles and isolated fast and slow MUs within the MG exhibited an initial spike of tension and throughout stimulation a low level of residual tension. Despite the minimal output of work, a contribution to fatigue could be detected in the poststimulation period, as well as a delayed facilitative effect. Possible mechanisms are discussed.

Effects of high-frequency (500-600 Hz), antidromic stimulation on primary and secondary spindle afferents.

The aftereffects of antidromic stimulation at 500 or 600 Hz on the discharge of isolated spindle Ia and II, and tendon organ Ib afferent fibers from the cat medial gastrocnemius muscle were examined to see what proprioceptive disturbances to expect when such "high-frequency," tension-attenuating stimulation is used to modulate contractions in orthotic applications. Three phases of poststimulation depression in spindle discharge were recognized: a complete pause in firing, a rapidly accelerating return of discharge, and a final more gradual approach to the control rate. When steady prestimulation discharge rates of Ia and II endings were equated through adjustment of muscle length, no obvious difference in effect on duration of the pause or position sensitivity was detected. Sensitivity to dynamic change in muscle length was also depressed, but responses returned earlier than when the muscle was held at a steady length. The dynamic responses of tendon organs were similarly depressed.

Nursing skills necessary for competency in the high-tech health care system.

Neighbors, Sullivan, and Eldred tell us how schools of nursing and institutions of nursing practice conform--or fail to conform--in regard to what constitutes basic nursing procedures. Are schools leaving the new graduate unprepared for everyday practice? A survey of association degree schools is revealing.