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Biomedical subjects

M B Bromberg

Publications and source records attributed to M B Bromberg.

At least 73 records · Page 4Linked to original sources
PubMed1988

Neurological abnormalities associated with remote occupational elemental mercury exposure.

We examined 502 subjects, 247 of whom had occupational elemental mercury exposures 20 to 35 years previously, to identify potential exposure-related neurological abnormalities. Few significant (p less than 0.05) differences existed between exposed and unexposed subjects. However, multiple linear regression analysis demonstrated several significant correlations between declining neurological function and increasing exposure as determined by urine mercury measurements from the exposure interval. Subjects with urine mercury peak levels above 0.6 mg/L demonstrated significantly decreased strength, decreased coordination, increased tremor, decreased sensation, and increased prevalence of Babinski and snout reflexes when compared with the remaining subjects. Furthermore, subjects with clinical polyneuropathy had significantly higher peak levels than normal subjects (0.85 vs 0.61 mg/L; p = 0.04), but not increased exposure duration (20.1 vs 20.8 quarters; p = 0.34), and 28% of subjects with peak levels above 0.85 mg/L had clinical evidence of polyneuropathy, compared with 10% of remaining subjects (p = 0.005). Although exposure was not age dependent, several neurological measures showed significant age-mercury interaction, suggesting that natural neuronal attrition may unmask prior exposure-related subclinical abnormalities.

Aging↗
PubMed1988

Chorea and dystonia: a remote effect of carcinoma.

A 45-year-old woman with an acquired multifocal neurologic syndrome, including chorea, dystonia, cerebellar dysfunction, multiple cranial neuropathies, and pure sensory neuropathy, was found at autopsy to have oat cell carcinoma. Neuropathologic examination revealed several features typically associated with remote effects of malignancy on the nervous system. We believe that this is the first described case of chorea as a remote effect of malignancy.

Carcinoma, Small Cell↗
PubMed1987

Evidence for reactive synaptogenesis in the ventrolateral thalamus and red nucleus of the rat: changes in high affinity glutamate uptake and numbers of corticofugal fiber terminals.

High affinity glutamate uptake into corticofugal fiber terminals was measured in the ventrolateral thalamus and red nucleus at varying time intervals after lesions were made by kainic acid in the contralateral interpositus nucleus of the cerebellum in rats. Under similar conditions the density of cortical fiber terminals was estimated using the Fink-Heimer impregnation technique. 1. Glutamate uptake steadily increased in the ventrolateral thalamus up to 60 days after lesions in the contralateral cerebellum. 2. Similar changes were noted in the red nucleus. 3. The changes were dependent on the integrity of corticofugal fibers to the thalamus and red nucleus. 4. No changes in uptake of gamma-aminobutyric acid were noted. 5. Saturation curves for glutamate uptake suggested a change in the maximal number of transport sites. 6. Fink-Heimer degeneration studies showed an increase in cortical terminals in the ipsilateral ventrolateral thalamus and in both rostral and caudal regions of the red nucleus following lesions in the contralateral interpositus nucleus. The data are consistent with an increase in the number of cortical fiber terminals in reaction to loss of cerebellar input to the ventrolateral thalamus and red nucleus. This study correlates anatomical and biochemical evidence for collateral sprouting in a model based on electrophysiologic data in the red nucleus and extends the model to include the thalamus.

Animals↗
PubMed1987

Peripheral and spinal inputs to physiologically identified thalamic and nonthalamic relay neurons in cat cuneate nucleus.

A single-unit population study of the feline cuneate nucleus was carried out to identify principal neuron types, their distribution within the nucleus, pattern of peripheral activation, and receptive field characteristics. Units were also tested for response to isolated dorsal column or dorsolateral funicular electrical stimulation. The nucleus was explored in a uniform pattern, and sample size was optimized by applying the search stimulus shocks to the dorsal spinal cord. Single units were defined as spinal afferents, cuneothalamic-relay (CTR) neurons, and non-cuneothalamic-relay (non-CTR) neurons. The following features were observed: The distribution within the nucleus of specific cell types agreed with cytoarchitectural studies: Spinal afferent fibers were superficial and caudal; 22% of neurons were CTR neurons; CTR neurons were most dense in the middle of the nucleus and were largely separate from non-CTR neurons. Of the 58 neurons tested for response to isolated dorsal column and dorsolateral funicular stimulation, 24% were activated from both tracts. Convergent input from the off-focus periphery (defined as other than the ipsilateral forelimb) was detected in both CTR and non-CTR neurons, most commonly from the contralateral forepaw. Several neurons were activated from three limbs. Thirty-seven percent of units were unresponsive to hair movement, touch, muscle palpation, or movement of joints. Compared to spinal fibers and non-CTR neurons, CTR neurons were most likely to have an identifiable input.

Afferent Pathways↗
PubMed1983

Preservation of physical dimensions in a model of reactive synaptogenesis in the red nucleus.

Collateral sprouting of cerebral cortical fibers in the red nucleus following destruction of the interpositus nucleus may be effective in restoring activity of rubral neurons. Shrinkage of the deafferented red nucleus was measured to estimate its effect on recording neural activity and its contribution as a stimulus for sprouting. The results suggest that rubral morphology is preserved during the early time course of collateral sprouting when electrophysiological changes are evident.

Animals↗
PubMed1983

Glutamate or aspartate as a possible neurotransmitter of cerebral corticofugal fibers in the monkey.

We measured high affinity glutamate uptake in subcortical projection sites of monkey (Macaca fascicularis) 8 weeks after unilateral ablation of Brodmann's areas 4 and 6. Uptake decreased ipsilateral to the lesion in ventrolateral nucleus of thalamus, caudate nucleus, and pons. Uptake also decreased contralateral to the lesion in cervical and lumbar spinal cord. These results suggest that L-glutamate (or possibly L-aspartate) is a neurotransmitter of corticofugal fibers in primate.

Animals↗
PubMed1981

Doubly projecting neurons of the dorsal column nuclei.

In a sample of 1700 neurons recorded from the dorsal column nuclei of the cat, 44 (2.6%) were found to send an axon down the dorsal spinal cord. Fully 70% of these caudally projecting neurons also sent an axon to the ventral thalamus. Nearly all had small cutaneous receptive fields distally on the forelimb and displayed response properties similar to other neurons of the dorsal column nuclei. Most were isolated along the lateral and medial margins of the cuneate nucleus rostral to the obex, and many were excited or inhibited by pericruciate cerebral stimulation. A few clearly were excited monosynaptically from the contralateral cerebral cortex at a latency that required the largest pyramidal tract fibers. These neurons probably comprise an important subset that regulates the flow of sensory information in spinal and brainstem somatic sensory pathways.

Animals↗
PubMed1981

Decreased glutamate uptake in subcortical areas deafferented by sensorimotor cortical ablation in the cat.

Evidence that L-glutamate is a neurotransmitter of corticofugal fibers was sought by measuring changes in several biochemical markers of neurotransmitter function after pericruciate (sensorimotor) ablations in cats. Two weeks after cortical ablation, samples from various brain regions were analyzed for high affinity uptake of glutamate, gama-aminobutyric acid (GABA), glycine, alanine, and tyrosine. Amino acid levels and the activity of choline acetyltransferase (CAT) also were determined. High affinity glutamate uptake is decreased relative to the opposite side in areas of the nervous system which lost a predominantly unilateral corticofugal projection. These areas include the caudate nucleus, ventrolateral thalamic nucleus, red nucleus, basis pontis, and cervical and lumbar spinal cord. No significant changes were found in the uptake of other amino acids or in CAT in these regions. Changes in the levels of amino acids were significant only in ventrolateral thalamus where there was a 33% decrease in glutamate on the deafferented side. The data suggest that L-glutamate is a neurotransmitter of corticofugal fibers to many subcortical areas related to motor control.

Amino Acids↗
PubMedDate not supplied

The low incidence of suprascapular nerve injury after primary repair of massive rotator cuff tears.

We measured the incidence of cuff retear and injury to the suprascapular nerve after mobilization and repair of a massive rotator cuff tear. Of one hundred four rotator cuff repairs performed over a 5-year period, 10 patients (7 men and 3 women, age range 22 to 68 years) had primary repairs of massive rotator cuff tears requiring cuff mobilization and an acromioplasty as their only procedure. These patients were evaluated at a mean of 2.5 years (range 2.0 to 3.0 years) after surgery. At follow-up electromyographic examination confirmed that 1 of the 10 patients had an iatrogenic suprascapular nerve injury, whereas ultrasound evaluation revealed that 2 of 10 repairs failed. Pain relief was achieved in the eight patients with intact repairs and not in the two with recurrent tears. All patients had some limitation of active motion or strength, especially in external rotation. Thus 7 of 10 patients had neither evidence of nerve injury nor recurrent rotator cuff tears yet still showed limited active motion or weakness. It appears that operative injury to the suprascapular nerve during cuff mobilization can occur, but other factors such as inadequate cuff muscle function are more frequently responsible for the poor functional outcomes seen after successful repairs of massive rotator cuff tears.

Adult↗