Biomedical subjects
J S Lieberman
Publications and source records attributed to J S Lieberman.
Serum creatine phosphokinase variations in dystrophic mice.
Explore the source record for details and available documents.
Perinatal neuropathy as an early manifestation of Krabbe's disease.
An asymptomatic child with antenatally diagnosed globoid cell leukodystrophy was found to have electrodiagnostic evidence of peripheral neuropathy at 7 weeks of age. The earliest prior such evidence in the literature was in a 6-month-old-child. Thus, peripheral neuropathy can be both the initial manifestation and a very early finding in Krabbe's disease.
Instrumental methods in the study of vascular disease.
Explore the source record for details and available documents.
Response of muscle spindle primary endings to static stretch in acute and chronic spinal cats.
To evaluate fusimotor activity, the response of muscle spindle primary endings to static stretch was recorded from group Ia fibers in 8 control cats and in 31 cats at 3, 6, 14, 30, and 60 days after lumbar spinal cord transection. The spindle responses and clinical status of each group were compared with those of the control group. At 3 days after transection, the cats were hypotonic and mildly hyperreflexic. Spindle responses were significantly depressed. By day 6, the cats were mildly hypertonic and significant spindle recovery had occurred, although the responses were still significantly depressed from control levels. Spindle responses, hypertonia, and hyperreflexia continued to increase to day 30. At this time, spindle responses remained significantly depressed, although the cats were markedly hypertonic and hyperreflexic. A significant change in spindle activity or clinical status did not occur from 30 to 60 days after transection.
Fast and slow skeletal muscles: contractility evaluated by paired stimuli in mice.
The purpose of this study was to evaluate a technique for in vitro study of mouse skeletal muscle, to determine if paired stimuli would allow estimation of new time parameters of contraction. Conventional tension measurements were obtained, plus the time measurements from the paired stimulus studies. The muscles were also subjected to fatigue by repetitive tetanization. A fast muscle (extensor digitorum longus or plantaris) and a slow muscle (soleus) were studied in each preparation. Studies were conducted at physiologic (35C) and at nonphysiologic (20C) temperatures. Data obtained indicate that this isometric in vitro method allows subdivision of results into 3 categories of effect due to treatment related to the functional muscle compartments: 1) chronotropic-excitation contraction coupling mechanisms, 2) inotropic- contractile elements, and 3) metabolic (fatigue)-energy supply mechanisms. When results as 20C were compared with physiologic temperature, a negative chronotropic effect was observed for all parameters in all 3 muscles. A positive inotropic effect was observed for twitch with no change or a negative effect for all other tension parameters. The lower temperature produced slight protection from fatigue. Models were developed to demonstrate how data from isometric studies fit the original concepts developed using isotonic methods. The model and method should prove of value in detecting the acute effect of drugs or of other therapy imposed on skeletal muscles.
Fast and slow skeletal muscles: effect of secobarbital on contractility of muscles from mice.
In vitro studies were performed on fast and slow muscles from mice to determine if secobarbital sodium (SCB) has a direct effect on muscle contractility. All preparations were curarized and stimulation was direct. After baseline studies, SCB was added to the muscle bath in 1 of 4 concentrations-10, 20, 100 and 200 microgram/ml. Tetanic tension was reduced for both muscle types at SCB concentrations greater than or equal to 20 microgram/ml, and loss was progressive with increasing dose. In contrast, twitch tension (P) was increased by SCB at the 2 higher concentrations. The increase in P was due to an increase in rate of tension development plus prolongation of the time parameter (duration) of the twitch. Fatigue was accelerated by SCB for both muscle types. The results indicate that SCB has a direct and similar effect on fast and slow skeletal muscles. The probable sites of action of the drug are the excitation contraction coupling mechanisms and the mechanisms for energy production and/or utilization.
Serial phrenic nerve conduction studies in candidates for diaphragm pacing.
Serial phrenic nerve conduction studies in 3 patients with high cervical cord injuries have demonstrated a pattern of function that changes with time. Nerves may be responsive initially and may then become unresponsive only to have responses reappear at a later date. Before a final decision is made about phrenic nerve viability prior to diaphragm pacing, serial studies should be carried out for at least 6 weeks postinjury on initially responsive nerves, and for at least 2 years postinjury on nonresponsive nerves or those with a changing functional pattern.
Intraarterial secobarbital: muscle injury evaluated by electrodiagnosis in four cases.
A syndrome of severe upper extremity pain, swelling and weakness following intraarterial injection of illicit secobarbital was evaluated in 4 patients. Although the involved muscle mass was small, serum muscle enzymes were markedly elevated. Electromyography (emg) revealed fibrillation and positive sharp wave potentials at 7 days. Motor unit action potentials were of low amplitude and of brief duration but markedly reduced in numbers, a mixture of myopathic and neuropathic changes. Motor nerve conduction velocities and latencies were normal, but M-wave amplitudes were small. Serial studies in 1 patient revealed persistent fibrillation and positive sharp waves in all involved muscles with absent voluntary contraction in the ulnar muscles and no response to stimulation of the ulnar nerve at 60 days postinjection. The emg and conduction studies for the median nerve distribution were normal except for the abnormal rest activity. A muscle biopsy (on day 66) in this patient revealed findings compatible with neuropathy, myopathy and vasculitis. The results indicate that electrodiagnostic studies may be of value for prognosis in these cases by evaluating the extent of neuromyopathic involvement.
Cerebellar ataxia. Anatomical, physiological and clinical implications.
Explore the source record for details and available documents.
Phrenic nerve conduction studies in the evaluation of ventilatory problems in patients with cranio-cervical trauma.
Five patients with hypoventilation and paresis of the diaphragm following trauma to the cervical spinal cord, brain stem, or both, were evaluated with phrenic nerve conduction studies while being considered for implantation of a phrenic nerve stimulator. Several distinct patterns of phrenic nerve function were elicited in the various cases, allowing accurate predictions and management decisions to be made. Phrenic nerve conduction studies are felt to be a valuable diagnostic tool in the management of the hypoventilating patient with cranio-cervical trauma. The procedure is safe, rapid, and easily performed at the bedside.
D-norgestrel: an estrogen-free, cyclic oral contraceptive.
Explore the source record for details and available documents.
Alpha motoneuron responses to natural stimuli in decerebellate cats.
The responses of single alpha motoneurons to various "natural' stimuli were recorded from dissected ventral root filaments in lightly anesthetized control and recently decerebellate cats. The identity of the motoneurons was established by recording the unitary responses to orthodromic stimulation of nerves innervating the triceps surae muscles in the hindlimb. We recorded only the activity of units which responded to electrical stimulation of the medial or lateral gastrocnemius nerves, though some units responded to stimulation of both these nerves, and some also responded to stimulation of the posterior tibial nerve. The distributions of unit latencies and amplitudes did not differ between the two groups of animals. Baseline firing rates were also similar. However, unit firing rates in response to neck extension, ipsilateral hindfoot dorsi- or ventral-flexion were significantly higher in decerebellate than in control cats. The discharge rates in response to other stimuli, including neck flexion, pinna stimulation, and noxious stimulation in the hindlimb, were not significantly different between the two groups. Since the alpha motoneurons showed an increase in responsiveness only to some stimuli, specific mechanisms probably explain this release. The most important mechanism seems to be a loss of inhibition normally exerted by the cerebellum on vestibular and joint proprioceptive reflexes. The pathways to the ventral horn cells are thought to involve the vestibulo-spinal and reticulo-spinal tracts.
Differences in proximal and distal conduction velocities of efferent nerve fibers to the medial gastrocnemius muscle.
Explore the source record for details and available documents.
Cryogenic lesions in the ventrolateral nucleus and pulvinar. Fusimotor effects.
Explore the source record for details and available documents.
Spinal mechanisms underlying the effects of unilateral ablation of areas 4 and 6 in monkeys.
Explore the source record for details and available documents.
Presynaptic neuromuscular inhibition by porphobilinogen and porphobilin.
The rat hemidiaphragm was studied in vitro as a test system to evaluate the effects of heme precursors and the uroporphyrins upon neuromuscular excitability. Porphobilinogen and porphobilin had no effect on the resting miniature end-plate potential frequency, but the K(+)-augmented frequency was significantly reduced. Porphobilin and porphobilinogen gave 50% of their maximal effect at concentrations of 0.008 and 0.6 mug/ml, respectively; the effect increased with concentration. Uroporphyrin I at 0.05-1.0 mug/ml caused a 25% decrease in frequency, but the effect did not increase with concentration. At similar concentrations, uroporphyrin III was without effect. The concentrations of porphobilin and porphobilinogen effective in inhibiting the K(+) stimulation, which are several orders of magnitude lower than the effective concentrations of simple amino acids, are those which might reasonably be expected in the sera of patients with acute intermittent porphyria.