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Biomedical subjects

A Carmon

Publications and source records attributed to A Carmon.

At least 19 recordsLinked to original sources
PubMed1986

A new animal model for action myoclonus.

Morphine was injected into a catheter implanted chronically into the intrathecal space of rats. Three to eight minutes after drug administration, 80% of the rats developed arrhythmic stimulus-sensitive jerks that lasted up to 1 hr. The morphine-induced myoclonic activity was markedly reduced by naloxone. Methadone, pethidine, and etorphine failed to produce the syndrome. In spinally transected rats, morphine injected below the level of transection did not produce the syndrome. No significant changes in PaCO2 and PaO2 were produced by morphine before and throughout the period of myoclonic activity. Neither did induced hypoxia augment the effect of morphine. However, irreversible hypoxic-ischemic cell changes were noticed in some brain regions. The phenomenon described here resembles the human syndrome of action myoclonus and may serve as an animal model for studying the mechanism of that neurological disorder.

Animals↗
PubMed1985

Effect of alpha-chlorohydrin on metabolism and testosterone secretion by rat testicular interstitial cells.

The direct effect of alpha-chlorochydrin (alpha-CH) on basic metabolism (glucose utilization and oxygen consumption) and testosterone secretion by isolated rat interstitial cells (I-cells) has been studied. In the range of concentrations between 5 and 100 microliter/ml, only the highest doses of alpha-CH decreased cell vitality and their histochemical stain for 3 beta-HSD. Oxygen consumption of I-cells was depressed at all doses higher than 10 microliter/ml and this effect was reversible only with doses lower than 50 microliter/ml. glucose utilization by I-cells was depressed significantly by alpha-CH and this effect was particularly dramatic with doses higher than 50 microliter/ml. alpha-CH decreased testosterone secretion by I-cells, with maximal effects at 100 microliter/ml. I-cells responded to hCG challenge by increasing testosterone secretion, and hCG prevented the toxic effect of alpha-CH at the lowest dose (10 microliter/ml) of alpha-CH, but failed to overcome the effects of a high dose (100 microliter/ml).

3-Hydroxysteroid Dehydrogenases↗
PubMed1984

Rhythm length and hemispheric asymmetry.

Conflicting evidence has appeared in the literature concerning hemispheric asymmetry in the perception of rhythm. The present study investigated the effects of rhythm length on relative cerebral dominance. Twenty-four subjects were presented with sequences of one to four time intervals bounded by light flashes. The subjects' task was to determine if two such sequences were the same or different. The first rhythm was presented in both visual fields and the second only to one visual field. Reaction times and number of errors were recorded. It was found that increasing rhythm length resulted in a shift in cerebral dominance from left to right hemisphere. An interpretation of these findings was suggested in terms of the preferred mode of processing of each hemisphere, analytic vs. holistic.

Eye Movements↗
PubMed1983

A model for the temperature distribution in skin noxiously stimulated by a brief pulse of CO2 laser radiation.

The application of localized noxious heat stimuli to the skin, generated by brief infrared radiation pulses emitted by a CO2 laser, is a relatively new experimental technique for the thermal induction of pain in humans and in experimental animals. This study proposes a model for the spatial (3-dimensional) and temporal distribution of the skin temperature during and following a radiation pulse. The heat equation is written and solved, using thermal and optical constants of human skin reported in the literature. The solution is approximated, with a very small error, by a closed form expression, having a simple physical interpretation. This model is applied to analyze a typical set-up currently in use in our laboratory. The results show a significant difference between the temperature of the surface of the skin and that of the border between the epidermis and the dermis, which is the location of the most superficial receptive nerve ends. It is shown that, for the set-up examined, these nerve ends reach a temperature of 45 degrees C, known to be the human pain threshold, 30-40 ms after pulse onset. Moreover, it is also shown that they may remain above threshold temperature for up to a few hundreds of milliseconds (considerably outlasting pulse cessation). In addition, it is shown that the area in which nerve ends reach this threshold is a circle with a very small radius (1-2.5 mm). The implications of the results on the double sensation experienced by humans, and on the extremely powerful EEG correlates, are discussed.

Humans↗
PubMed1980

Peripheral fiber correlates to noxious thermal stimulation in humans.

Minimal conduction velocities of peripheral nerves contributing to acute thermal pain sensation in human volunteer subjects were calculated. Purely thermal stimulation was administered by a low power laser beam directed at the subjects' fingers, and subjective pain responses correlated with a peak in the event-related brain potential (ERBP). These cerebral responses were found to preclude C fiber peripheral activity from this phenomenon.

Cerebral Cortex↗
PubMed1980

Somatosensory evoked potentials and noxious stimulation in patients with intractable, noncancer pain syndromes.

Investigations of the evoked potentials (EPs) to noxious laser stimulation have indicated consistent strong linear relationships between subjective response (R), stimulus intensity (S), and EP amplitude (A). Thirty patients with chronic intractable benign pain syndromes (CIBPS) were tested to determine whether their patterns differed from previous studies with normal volunteers. Nearly half of the CIBPS patients were found to be relatively insensitive to acute pain stimuli. A large number were also found to show negative relationships between S and A. These differences from control subjects were considered of potential importance in their implications concerning the nature of chronic pain and its differences from the acute pain process.

Adult↗
PubMed1980

Single trial analysis of evoked potentials to noxious thermal stimulation in man.

Thermal (laser) evoked responses were obtained from 13 male volunteers. A single trial analysis technique with a latency adjusting adaptive filter was used to analyze evoked response amplitudes. Significant and substantial within-subject linear correlations were found between the magnitude (A) of the primary waveform (RMS muV of the P200--N300-P400 complex ) and subjective pain response (R) as well as stimulus intensity (S). Since subjective pain response was strongly correlated with stimulus intensity, the partial correlation coefficients were calculated for R vs. A with S controlled, and S vs. A with R controlled, for each subject. The partial correlations revealed a much stronger relationship between subjective response and the evoked response amplitude, suggesting that the primary complex may measure neural events in the pain perception process rather than transduction and transmission of the stimulus event.

Computers↗
PubMed1978

Correlation of subjective pain experience with cerebral evoked responses to noxious thermal stimulations.

The relationships between different parameters of the evoked cerebral response to noxious thermal stimulation, stimulus intensity, and subjective pain were investigated in seven normal human volunteers. The evoked response was characterized by late events: a small negative peak at 164--180 ms, followed by a high amplitude positive peak at 372--391 ms. The only correlation found in this study was between the amplitude of the positive component and the qualitative and quantitative aspects of the verbal report of pain. This was manifested by a linear trend of association: an increase in the evoked response amplitude was accompanied by an increase in the magnitude of the subjective sensation. The findings suggest that the evoked response to noxious heat reflects not a mere transduction of the physical parameters of the stimulus, but rather a complex interpretative action at the cerebral level.

Evoked Potentials↗
PubMed1977

Responses of paranoid and nonparanoid schizophrenics in a dichotic listening task.

Differences in attentional processes between normals, paranoid schizophrenics, and nonparanoid schizophrenics were studied by delivering dichotically presented digits for identification. Thirty paranoid schizophrenics (20 acute and 10 chronic), 30 nonparanoid schizophrenics (20 acute and 10 chronic), and 20 normal controls were tested. The data were analyzed in terms of the overall level of correct identification of stimuli presented to the two ears, the number of shifts in report from one ear to the other, and the magnitude of ear differences in recall. The results showed that overall level of performance was higher for the normals than for the schizophrenics; the number of ear shifts was greater for normals and nonparanoid than for paranoid schizophrenics; and ear differences were biggest for the paranoid schizophrenics and smallest for the normals. The results were interpreted in terms of differences in attentional style and rate of information processing.

Adolescent↗