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Biomedical subjects

R G Feldman

Publications and source records attributed to R G Feldman.

At least 109 records · Page 6Linked to original sources
PubMed1980

Occupational lead exposure, nephropathy, and renal cancer.

A 48-year-old lead worker was found to have a cystic renal carcinoma during an evaluation of his occupational lead poisoning. Clinical studies showed elevated blood lead levels, impaired urinary concentrating ability, and reduced creatinine clearance. Histologic and electron microscopic studies showed this cystic tumor to be similar to renal carcinomas observed in animals with prolonged lead exposure. Lead content of the tumor was elevated (2.49 micrograms/gm) in comparison with adjacent renal tissue and with normal adult levels. In light of previous animal studies, this case adds increased evidence to the concern over the carcinogenic potential of prolonged lead exposure.

Adenocarcinoma↗
PubMed1980

Neuropsychological effects of industrial toxins: a review.

Quantitative assessment of nervous system function is essential in characterizing the nature and extent of impairment in individuals experiencing symptoms following workplace exposure. In recent years, the application of standardized neuropsychological tests to the evaluation of exposure to toxic industrial substances has significantly increased the understanding of the effects of these compounds. Within this review, the specific toxic neuropsychological effects of lead, carbon disulfide, trichloroethylene, perchloroethylene, mercury, styrene, and pesticides are discussed in detail. These discussions draw on our clinical experience with patients exposed to these substances as well as material from the medical literature. Factors affecting the utilization of these tests in occupational settings are also considered.

Carbon Disulfide↗
PubMed1980

Pattern shift visual evoked response in carotid occlusion.

Pattern shift visual evoked response (PSVER) latency has been shown to be an extremely sensitive but nonspecific measure of optic nerve dysfunction. The test has been most useful in detecting unsuspected demyelinating lesions of the optic nerve, but abnormal results have been reported in a variety of other conditions affecting the optic nerve, including ischemic optic neuropathy. We report a patient with left internal carotid artery occlusion, possibly secondary to neck trauma, with normal ophthalmological examination and abnormal PSVER. The suggested mechanism is subclinical optic nerve ischemia due to decreased blood flow in the ophthalmic artery. PSVER may have value as a sensitive indicator of internal carotid artery disease.

Adult↗
PubMed1980

Is L-DOPA drug holiday useful?

We studied 9 patients with severe, chronic Parkinson disease and complications of long-term L-DOPA therapy. After a "holiday" of 3 to 21 days, excess dopamine effects improved in all patients, and the baseline parkinsonian picture emerged. After reinstitution of L-DOPA therapy, often at lower doses than had been used previously, parkinsonian signs improved. Complications of immobility were seen in two patients; one had deep vein thrombophlebitis, and the other became depressed. In treating the individual patient, the risks of immobility despite aggressive attempts to prevent complications should be weighed against the possible improvement of parkinsonism. These findings suggest that a holiday from L-DOPA therapy may extent the drug's usefulness in treating Parkinson disease, perhaps by resensitizing striatal dopamine receptors in patients receiving the drug for prolonged periods.

Activities of Daily Living↗
PubMed1980

Clinical epidemiology of occupational neurotoxic disease.

Occupational exposures to neurotoxic chemicals have produced large outbreaks of illness in chemical and pesticide workers worldwide. Outbreaks of occupational neurologic disease in the United States have included (1) the Kepone episode in Hopewell, Virginia, in which 76 workers at a pesticide plant producing the chlorinated hydrocarbon insecticide, Kepone, developed a previously unrecognized syndrome of nervousness, tremor, ataxia, weight loss, opsoclonus, pleuritic and joint pain, and oligospermia; (2) an outbreak of 104 cases of autonomic neuropathy in polyurethane foam workers in Marblehead, Massachusetts, manifest principally by urinary bladder dysfunction, which followed exposure to a new catalyst, dimethylaminopropionitrile (DMAPN); and (3) an outbreak of acute mixed motor and sensory neuropathy in 48 plastic fabric workers in Columbus, Ohio, exposed to the solvent methyl butyl ketone (MBK). These outbreaks underscore the vulnerability of chemical workers to neurotoxins. In addition, occurrence of these large, easily detectable epidemics suggests that many more smaller clusters and single cases of neurologic disease of undetermined origin, particularly in younger adults, may be caused by exposure to occupational or to other toxic chemicals. Detection of the etiology of chemically induced neurologic illness requires a high index of suspicion and careful ascertainment of occupational history.

Adult↗
PubMed1979

Effects of dimepramine fumarate on physiological and cognitive behaviors of Parkinson patients.

Nine patients 55 to 74 years old with Parkinson's disease were tested before and after treatment with 50 to 225 mg dimepramine fumarate (CIBA G-31406) for about three weeks daily in order to determine the drug's effects on electrodermal responsiveness to a series of unpredictably occurring loud sounds. Twelve control subjects were tested and retested with the same procedure. In addition, the Parkinson patients received a number of cognitive tests before and after drug treatment. Results indicated that the drug tends to decrease autonomic arousal responses as measured by resting conductance levels, number of fluctuations in skin conduction per minute, orienting response, and habituation rate. These decreases in measures of arousal generally were accompanied by lowered performance scores on several tests of memory and temporal discrimination ability.

Aged↗
PubMed1979

Paget's disease and the nervous system.

Paget's disease usually is found in patients past the age of 40. Early presenting symptoms include headache, deafness, tinnitus, and pain due to radicular compression. The diagnosis is confirmed by radiographic features and elevated levels of serum alkaline phosphatase and urinary hydroxyproline. Bony overgrowth results in pressure on nearby soft tissues such as the brain, spinal cord, and certain peripheral nerves. The abnormally soft quality of the calvarial bone permits distortion by the weight of the brain. Dorsal inclination of the plane of the foramen magnum and the projection of the odontoid process into the posterior fossa lead to stretching of the brain stem over the odontoid process and the ventral margin of the foramen. Obstructive hydrocephalus may result. Sarcoma of the crainial vault may develop in cases of Paget's disease. Once cervicomedullary or spinal compression has occurred, surgical decompression may be necessary. Three drugs--calcitonin, disodium etidronate, and mithramycin--have been used with some benefit in the treatment of Paget's disease.

Adult↗
PubMed1979

Peripheral neuropathy in arsenic smelter workers.

We conducted a double-blind controlled study of individuals exposed to arsenic trioxide in a copper-smelting factory. Subjects fell into three categories of peripheral neuropathy: none, subclinical, and clinical. The subclinical group had no symptoms or signs of numbness or reduced reflexes, but did have reduced nerve conduction velocity and amplitude measurements. Clinical neuropathy groups had signs and symptoms of neuropathy and electrophysiologic abnormalities. The clinical and subclinical groups correlated with increased content of arsenic in urine, hair and nails. The incidence of subclinical and clinical neuropathy was greater in arsenic workers than in unexposed controls.

Adult↗
PubMed1979

Leukopenia-induction capacity of 6-MP metallo-purine complexes in the rat.

Six-MP and its palladium and platinum complexes of this compound were administered intraperitoneally to 28 day old Sprague-Dawley rats in dosages of 15 mg/kg, 26.85 mg/kg, respectively for 21 days. The leukopenia induction capacity of 6-MP was greater at the end of day 7 while the 6-MP-Pd complex evidenced a more drastic leukocyte reduction at the end of day 21. The platinum complex was less toxic, as demonstrated by greater weight gain, while treatment with the palladium complex resulted in approximately the same weight gain as that observed in rats treated with pure 6-MP.

Animals↗
PubMed1978

Cyclic alterations of blink reflexes: an EEG and EMG study during wakefulness and sleep.

Studies of the blink reflex were undertaken in twelve normal subjects during wakefulness and different sleep stages. The early R1 and the late R2 components of the reflex were analyzed. R1 was present in only one subject during stage I sleep and subsequently disappeared in stage II to IV. In all subjects, R2 was gradually diminished and totally disappeared during stage IV. During the REM stage, R1 was seen in only four-out-of-twelve subjects but all R2 returned. Alterations of R1 and R2 of the blink reflex during different sleep stages suggest that the underlying mechanism includes both supranuclear and infranuclear activities. Our finding strengthens further the notion of dual hyponogenic mechanisms for sleep.

Adult↗
PubMed1978

Baclofen for spasticity in multiple sclerosis. Double-blind crossover and three-year study.

Baclofen is a safe and effective means for treating spasticity associated with multiple sclerosis. We found no toxic effects on hepatologic, hematopoietic, or renal function, acutely or for over 3 years of follow-up. A statistically significant reduction was noted in frequency of spasms, and clonus, and there was improved range of joint movement, which enabled patients to maintain functional status for prolonged periods. For the more disabled patients, treatment with baclofen gave symptomatic relief of painful spasms and made immobility more tolerable. Optimum effect was achieved when baclofen was administered in the early stages of disease, before major disabilities became permanent.

Activities of Daily Living↗
PubMed1977

Azorean disease of the nervous system.

We studied a family of Portuguese ancestry from the Azores who suffered a progressive neurologic disease characterized by gait ataxia, features similar to Parkinson's disease in some patients, limitation of eye movements, widespread fasciculations of muscles, loss of reflexes in the lower limbs, followed by nystagmus, mild cerebellar tremor and extensor plantar responses. Two post-mortem examinations revealed loss of neurons and gliosis in the substantia nigra, nuclei pontis (and in the putamen in one case) as well as in the nuclei of the vestibular and other cranial nerves, columns of Clarke and anterior horns, in the spinal cord there were also loss of fibers in the fasciculi gracilis and mild changes in the pyramidal tracts. Comparison of the disease in this family with the findings reported in three families of similar ancestry, previously thought to have different disorders, suggests that they may all represent a single genetic entity with variable expression.

Adolescent↗