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Biomedical subjects

J S Kauer

Publications and source records attributed to J S Kauer.

63 records · Page 4Linked to original sources
PubMed1979

Alteration of posttraumatic ischemia in experimental spinal cord trauma by a central nervous system depressant.

Blood flow after severe experimental injury to the thoracic spinal cord was studied in cats, using a modification of the hydrogen clearance technique. Gamma hydroxybutyrate, a central nervous system depressant, was shown to markedly alter the ischemic response to injury if given during the early posttraumatic period. Other vasoactive drugs investigated had no effect on posttraumatic ischemia. Therapeutic intervention during the early posttraumatic period aimed at increasing blood flow while decreasing the metabolic requirements of the injured cord may prove of value in reversing or limiting some elements of long-tract dysfunction due to the secondary ischemic insult.

Animals↗
PubMed1977

Dopamine-sensitive adenylate cyclase within laminae of the olfactory tubercle.

There are three histological laminae within the rat olfactory tubercle: plexiform, pyramidal and polymorphic. We have assayed dopamine-sensitive adenylate cyclase in homogenates of frozen sections cut parallel to these laminae. Consecutive sections were cut of alternating thickness, 16 micron and 100 micron. The 16 micron sections were stained with toluidine blue to ascertain the depth and orientation of each section. The 100 micron sections were homogenized and assayed for dopamine-sensitive adenylate cyclase. Substantial levels of dopamine-sensitive adenylate cyclase were found within all three laminae. The results suggest that the enzyme occurs in cell processes, including dendrites, of the plexiform layer, and they are consistent with the localization of dopamine-sensitive adenylate cyclase in the pyramidal cells.

Adenylyl Cyclases↗
PubMed1977

Analysis of the onset phase of olfactory bulb unit responses to odour pulses in the salamander.

1. A method for delivering odour pulses of controlled onset, steady plateau and abrupt termination, has been developed and applied to a single unit study of mitral cell responses in the olfactory bulb of the salamander. The pulses have been monitored during the experiments near the site of stimulation on the olfactory mucosa.2. Responses have been categorized as excitatory or suppressive based on the initial response to the odour pulse.3. Initially excitatory responses had sustained discharges near threshold. With increasing concentration, the discharge changed to a brief burst followed by suppression. The briefest latency of a unit response was 120 msec, using stimulation of medium concentration, after the start of the pulse; the majority of units appeared to be excited within 200-300 msec. Ramp stimuli gave increasing periods of excitation as the rise time of the odour front became less abrupt.4. Initially suppressive responses showed suppression at all levels of concentration. The majority of units appeared to have an onset of suppression about 300-400 msec after the start of the pulse.5. These basic responses, involving suppression or excitatory-suppressive sequences, can be correlated with some basic properties of the synaptic circuits in the olfactory bulb. The time courses of the initial responses appear to be within the time periods of the inhalation cycle of the salamander, and therefore may reflect mechanisms of processing of natural olfactory stimuli.

Action Potentials↗
PubMed1974

Response patterns of amphibian olfactory bulb neurones to odour stimulation.

1. Responses of 199 single olfactory bulb neurones in the frog were observed with odour stimulation.2. To effect control over the concentration, flow rate and time course of the stimulus application, a simple olfactometer was developed and calibrated using a gas chromatograph. The stimulus pulses were monitored by recording the electro-olfactogram from the olfactory mucosa.3. Several categories of unit activity became evident after delivering many odour applications (637). Some odour applications did not cause any change in the spontaneous activity of the unit. This was classified as type N (no response) activity. Some applications caused a suppression of ongoing activity (type S activity). Some applications caused an excitation during the rising concentration phase of the stimulus pulse (type E activity). Three temporal patterns of excitatory responses were seen and these were categorized as subgroups of activity type E.4. Since each response type was seen with about the same frequency regardless of the odour used, this suggested that the temporal patterns of response per se were not coding for odour type.5. When odour concentration was manipulated for a unit showing suppressive (type S) activity at one concentration, then the unit tended to show qualitatively similar suppression at other concentrations as long as they were above threshold.6. When peak concentrations were manipulated for units showing excitatory (type E) activity, the temporal patterns of response could change dramatically. In many cases the units fired after one level of concentration had been reached and were subsequently suppressed with increase in concentration. Such ;concentration tuning' suggested that excitatory temporal patterns, in contrast to suppressive ones, were coding odour concentration information.7. The significance of the changes in temporal response patterns seen here, for experiments examining the relationships between odours using single unit response data, is discussed.

Action Potentials↗
PubMed1974

Responses of olfactory bulb neurones to odour stimulation of small nasal areas in the salamander.

1. Previous experiments have suggested that one way odours may be discriminated is by different spatial patterns of response at both the olfactory bulb and receptor level. The present experiments were designed to test to what extent the position of an odour on the receptor mucosa can influence the activity of olfactory bulb neurones.2. To deliver odours to small areas on the nasal receptor sheet a new method for local application of odour was developed. The flow rate, concentration, and time course of the odour were controlled using the olfactometer described in the preceding paper.3. In thirty olfactory bulb units in the salamander it was found that if the response of a unit to odour delivered to the entire exposed receptor epithelium were suppression (type S), then the unit tended to be suppressed when odour was delivered to a number of localized epithelial regions. If the response were excitation (type E) to stimulation of the entire epithelium, then stimulation to only one or two localized regions would elicit the maximum response.4. Different epithelial regions had the ability to cause excitation in the same bulbar unit depending on the odour being used. Two odours, camphor and amyl acetate, elicited maximum excitation when they were presented to different mucosal areas. The areas at which presentation of these odours gave excitation were surprisingly consistent from unit to unit and animal to animal.5. The data presented here suggest the presence of restricted excitatory receptive fields for some olfactory bulb neurones for a particular odour.6. The presence of spatial response patterns using odour delivery to small nasal receptor regions and thus the presence of receptive fields is discussed with reference to bulbar neuronal circuitry.

Action Potentials↗