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Biomedical subjects

S Gilman

Publications and source records attributed to S Gilman.

At least 163 records · Page 9Linked to original sources
PubMed1979

Exploring azimuth effects with an anthropometric manikin.

In these experiments, the effects of sound direction on the eardrum response of an anthropometric manikin (the KEMAR manikin) were investigated. Pure tones and pink noise (analyzed in 1/3-octave bandwidths) over a wide frequency range were used as signals as the manikin rotated 360 degrees with respect to a point source in a anechoic chamber. The simulated eardrum SPL was compared with the averaged human field-to-eardrum data reported by Shaw [J. Acoust. Soc. Am. 56, 1848--1861 (1974)]. It was concluded that the KEMAR manikin can be used up to frequencies of approximately 8.0 kHz, with (1) 1/3-octave pink noise signals to measure a response equivalent to tht obtained by averaging over a number of humans, and (2) pure-tone signals to measure the response equivalent to that of a single human having average head and ear dimensions.

Anthropometry↗
PubMed1978

Neuropathological changes in cerebellar biopsies of epileptic patients.

In 5 patients with pharmacologically intractable epilepsy, biopsy of the cerebellar cortex at the time of surface electrode implantation for therapeutic stimulation demonstrated marked degeneration of the Purkinje cell layer in every case. Two of the patients had never experienced a generalized convulsion. Comparison of these biopsy findings with the autopsy findings in two other groups of patients with a seizure disorder of different duration and severity and with the findings in other reported series suggests that permanent neuronal damage in epilepsy is related to the cumulative effects of the frequency and chronicity of the disorder. The pathogenesis remains unclear. The histopathological changes are identical to those seen in generalized cerebral hypoxia, but the observations in our series support the view that in epilepsy the pathogenesis may not be hypoxic.

Adolescent↗
PubMed1978

Speech disorders in cerebellar disease.

The areas of cerebellar damage most commonly associated with dysarthria were sought by reviewing the clinical, radiographic, surgical, and autopsy findings in patients with nondegenerative cerebellar disease. Case histories on 162 patients with focal cerebellar lesions were reviewed. All but 15 of the patients underwent surgery, and 28 had autopsies. Thirty-one of the 122 patients with adequate descriptions of speech had dysarthria. Twenty-two of these 31 dysarthric patients had exclusively or predominantly left cerebellar hemisphere disease; 7 had right hemisphere disease; and 2 had vermal disease. Only 19 of 41 patients with exclusively or predominantly left hemisphere disease had had normal speech before surgery. Dysarthria developed in isolated cases following cerebellar resections extending into the paravermal segments of the left hemisphere. There was no correlation between the extent of vermal damage and development of abnormal speech. Cerebellar speech function was most commonly affected with damage to the superior portion of the left cerebellar hemisphere.

Adult↗
PubMed1978

Changing the coronary-prone (type A) behavior pattern in a nonclinical population.

This report presents the design and initial findings of an attempt to reduce the risk of coronary heart disease in healthy men by modifying their type A behavior pattern. A group of 27 professional and executive volunteers, aged 39--59, who had been medically assessed as free from coronary heart disease, were randomly assigned to brief psychotherapy and behavior therapy groups. Each treatment group met for 14 sessions over a period of 5 months. Pre- and postmeasures of physiological (serum cholesterol, serum triglycerides, blood pressure) and psychological (anxiety, psychological symptoms, satisfaction) variables were taken. Results indicate that both treatment groups changed in the desired direction on most of the psychological and physiological variables without apparent change in habits of diet, exercise, smoking, or work load. The findings are provocative, but only tentative, leaving questions of clinical validity, durability, and generalizability unresolved. Nevertheless, they indicate that this approach to modifying type A behavior may reduce coronary risk and therefore warrants further exploration.

Adult↗
PubMed1978

Development and evaluation of a new water-soluble iodinated myelographic contrast medium with markedly reduced convulsive effects.

A new water-soluble myelographic contrast agent with more hydrophilic properties than metrizamide was developed and tested in the primate (Macaca mulatta) and the cat. A new animal model that allows study of the convulsive effects of intrathecally administered contrast agents in the awake monkey was designed. With this sensitive model the new contrast agent was shown to have a remarkable reduced convulsive effect when compared with metrizamide and other media. Intrathecal hypertonic solutions in the cat depress the evoked cortico-spinal responses whereas the neurotoxic effects of the iodinated water-soluble contrast media increase them. The net effect is a combination of the two actions.

Animals↗
PubMed1978

Alteration of Purkinje cell activity from transfolial stimulation of the cerebellum in the cat.

The activity of single Purkinje cells and other single neural units was recorded extracellularly from the cerebellar cortex of anesthetized cats during surface cerebellar stimulation with parameters similar to those used in human beings with epilepsy. At a stimulation rate of 0.5 Hz, most Purkinje cells responded with a simple stimulus-locked suppression of activity, although some showed more complex sequences of suppression and activation. At a stimulus rate of 10 Hz, essentially all responsive Purkinje cells showed a suppression of activity. Most of the other units responded to stimulation in the same manner. These effects were observed immediately adjacent to the stimulating electrodes and as far away as 6.5 mm. Therefore, surface stimulation of the cerebellum with parameters equivalent to those used in epileptic patients suppresses rather than activates Purkinje cells. These findings do not support the hypothesis that Purkinje cell activation accounts for seizure suppression in epileptic patients.

Animals↗
PubMed1977

Methods for measuring the temporal characteristics and filter response of electroacoustic impedance instruments.

Methods for determining the temporal response of electroacoustic impedance instruments are presented along with sample measurements from one instrument. The conditions under which reflex artifacts may occur are discussed in light of electrical measurements of filter response characteristics and measurements of the "threshold" of the artifact measured from two subjects with no acoustic reflex.

Acoustic Stimulation↗
PubMed1977

Effect of isotonic contrast agents on spinal reflexes in the cat.

The effects of isotonic solutions of three contrast agents, administered intrathecally, were studied in cats. A pronounced increase in the electrically evoked cortico-spinal responses and segmental spinal polysynaptic reflexes was recorded after administration of methylglucamine diatrizoate. Injection of methylglucamine iothalamate resulted in an increase of the amplitudes of these reflexes, while metrizamide did not show any consistent effect. The data suggest that water-soluble media have direct effects upon spinal gray matter.

Animals↗
PubMed1977

Long-term surface stimulation of the cerebellum in the monkey. I. Light microscopic, electrophysiologic, and clinical observations.

The effects of chronic implantation of platinum electrodes over the surface of the cerebellum and of stimulation through these electrodes was studied in monkeys. Stimulation parameters were similar to those used in epileptic human beings; two animals received continous stimulation and two received intermittent stimulation in eight-minute on-off cycles. Both stimulating and non-stimulating electrodes became encapsulated in dense reactive fibrous tissue. As determined by light microscopy, continous stimulation resulted in widespread loss or damage to Purkinje cells. Intermittent stimulation led to damage similar in extent to mechanical damage caused by control electrodes. The impedance of the stimulating electrodes was higher after long-term than short-term implnatation and increased progressively in animals stimulated intermittently. There were no clinical neurological signs of cerebellar dysfunction, even in animals with extensive damage.

Animals↗
PubMed1977

Long-term surface stimulation of the cerebellum in the monkey. II. Electron microscopic and biochemical observations.

Phase and electron microscopy were used to study the effects of chronic intermittent or continuous stimulation applied to the surface of the cerebellum with bipolar platinum electrodes in monkeys. Damage under the anodes consisted of swelling of neuropil, variable loss of Purkinje cells, and a variable increase in fibrous glial processes. Under the cathode there was marked loss of Purkinje cells, thinning of the molecular layer, moderate swelling, occasional phagocytes with lipofuscin granules, and often an increase of fibrous glial processes. Despite the damage, normal appearing synaptic terminals remained in all layers under both anode and cathode, though sparser in fibrotic areas Gamma-aminobutyric acid (GABA) concentrations were decreased beneath the cathodes, reflecting the loss of Purkinje cells and other GABA-containing cells, and spermidine concentrations were increased in areas with increased fibrous glial processes.

Animals↗
PubMed1976

Bone conduction thresholds for normal listeners in force and acceleration units.

In a previous article we reported on the standardization of normal hearing for bone conduction. All of our findings were reported in force units. Because many international users of this information express such findings in units of acceleration, we have, at the Editor's request, converted our force units into acceleration units to increase the scope of our results and to enhance their comparison with other investigations. This note presents data which may be useful to organization concerned with the development of standards for normal hearing by bone conduction.

Acceleration↗