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Biomedical subjects

C Hummel

Publications and source records attributed to C Hummel.

30 records · Page 2Linked to original sources
PubMed1994

A comparison of the antinociceptive effects of imipramine, tramadol and anpirtoline.

The pain relieving properties of imipramine (100 mg orally), tramadol (150 mg orally), and anpirtoline (60 mg orally) were compared in 16 healthy subjects in a cross-over, double-blind, randomized, and placebo-controlled study. Anpirtoline exhibits analgesia which is possibly mediated via serotoninergic pathways, whereas tramadol exerts its effects at opioid receptors. The pain-relieving effect of the tricyclic antidepressant imipramine may involve both serotoninergic and opioid mechanisms. Chemo-somatosensory event-related potentials (CSSERP) were recorded after painful stimulation of the nasal mucosa with carbon dioxide. Subjects rated the perceived intensity of the stimuli by means of a visual analogue scale. In addition, acoustically evoked responses were recorded, the spontaneous EEG was analyzed in the frequency domain, the subjects' vigilance was assessed in a tracking task, and side effects of the drugs were monitored. Anpirtoline and tramadol produced a decrease of both CSSERP amplitudes and subjective estimates of pain, the effects of the former compound being greater. In contrast, after administration of imipramine no change of CSSERP amplitudes could be detected, whereas the subjective estimate of pain intensity decreased significantly. This was accompanied by a significant decrease of arousal indicating that pain relief produced by acute administration of imipramine was primarily related to its sedation action. The analgesic properties of anpirtoline were demonstrated in man. Tramadol was characterized as a week opioid analgesic. In contrast, imipramine appeared to produce its pain-relieving effects predominantly by non-specific actions. It is hypothesized that different analgesics may change ERP sources in a drug-specific manner.

Administration, Oral↗
PubMed1994

Dose-related effects of ibuprofen on pain-related potentials.

1. The aim of this study was to investigate the dose-related effects of ibuprofen (placebo, 400 and 800 mg rac-ibuprofen [Aktren], administered orally) on experimentally-induced tonic and phasic pain. 2. Eighteen volunteers participated in this randomized, double-blind, three-fold cross-over study. Measurements were obtained before and 90 min after administration of the drugs. Phasic pain was produced by CO2 pulses of two concentrations applied to the right nostril. The left nostril was stimulated with a constant stream of dry air which produced a tonic painful sensation described as dull and burning. Subjects rated the intensity of the painful stimuli by means of visual analogue scales. In addition, chemo-somatosensory event-related potentials (CSSERP) were also recorded in response to phasic painful CO2 stimuli. 3. While mean intensity estimates of both tonic and phasic painful stimuli showed a non-significant dose-related decrease, a statistically significant dose-related decrease was observed for CSSERP amplitudes. 4. In conclusion, in order to investigate analgesic drug effects, CSSERP appear to be a more sensitive measure compared with psychophysically obtained responses.

Adult↗
PubMed1994

Magnetic source localization and morphological changes in temporal lobe epilepsy: comparison of MEG/EEG, ECoG and volumetric MRI in presurgical evaluation of operated patients.

Is MEG source analysis able to precisely locate the primary focal epileptic activity? 22 patients with pharmacoresistant temporal lobe epilepsy were recorded during presurgical evaluation simultaneously with multichannel MEG/EEG and invasive (subdural) electrodes to evaluate the increase of information gained by MEG concerning the localization of focal epileptic activity and lesions. With this systematic study it should become clearer how often MEG can establish a diagnostic bridge between function and morphology. In addition, MEG localization accuracy of focal epileptic activity was to be validated empirically by invasive EEG recordings and postsurgical outcome. Spikes in the MEG were used for magnetic source localization, and the result was combined with magnetic resonance imaging (MRI). All patients definitely suffered from temporal lobe epilepsy and revealed a structural abnormality in MRI. 17 patients with lesions in the temporal lobe were operated meanwhile and became markedly improved or seizure free. In 7 of 8 patients with a tumor and validated operation outcome, a very close correlation of the 3D-magnetic source localization and the border of the tumor in the brain was found (distance less than 10 mm). In 8 of 9 patients with a temporal/hippocampal atrophy and validated operation outcome, dipoles of epileptiform activity were located within the atrophic lobe.(ABSTRACT TRUNCATED AT 250 WORDS)

Brain↗
PubMed1991

The mucosal potential elicited by noxious chemical stimuli with CO2 in rats: is it a peripheral nociceptive event?

Negative mucosal potentials (NMPs) were recorded from the nasal respiratory mucosa in rats following retrograde stimulation with CO2 through a tube advanced to the nasopharynx. Local application of capsaicin (3 mg in 0.3 ml solvent, n = 5) and lidocaine (31 mg in 0.3 ml solvent, n = 5) eliminated the NMPs and cortical responses in the EEG. A quantitative reduction in NMPs was found following systemic pretreatment with capsaicin (cumulative dose, 200 mg/kg, n = 4), but not with guanethidine (50 mg/kg s.c., n = 4). Blood flow measurements and NMPs were obtained from the same recording position (n = 4). Onset of blood flow changes (1200-4800 ms) appeared significantly later than the onset of NMPs (120-500 ms). On the basis of these results a sensory neurogenic origin of the NMP is assumed.

Animals↗
PubMed1990

Effects of pentazocine and acetylsalicylic acid on pain-rating, pain-related evoked potentials and vigilance in relationship to pharmacokinetic parameters.

Achieving objective and quantitative measurement of experimental pain in human volunteers and establishing the impact of drugs remains a difficult task. This problem may be overcome by employing a method which allows the simultaneous measurement of pain ratings elicited by standardized stimulation of the nasal mucosa by carbon dioxide, together with pain-related chemo-somatosensory evoked potentials (CSSEP) and vigilance. We assessed the effect of pentazocine and acetylsalicylic acid on these parameters in 14 human volunteers and related the effects to the pharmacokinetic parameters of the drugs measured at the same time. Pentazocine was found to reduce the pain ratings as well as the amplitudes of the pain-related evoked potentials and to increase their latencies. Vigilance (measured by EEG power spectra and performance of a tracking task) was also significantly reduced. These effects were observed during the distribution phase and the first period of the terminal elimination phase of the drug. Acetylsalicylic acid had no significant effects on pain ratings, but reduced the amplitudes of the event-related potentials when compared to placebo controls. At the same time a slight, but significant, effect on vigilance (reduced performance of the tracking task) was observed. These effects could not be related to the presence of unmetabolized acetylsalicylic acid in the plasma. They appeared at later times when only salicylic acid was left. It is concluded that chemical stimuli of sufficient intensity produce pain which may be suppressed by opioid analgesics such as pentazocine. The effect of acetylsalicylic acid on this experimental pain did not reach significance for all measured parameters under the experimental conditions chosen. The changes in vigilance and in the amplitudes of pain-related chemo-somatosensory evoked potentials indicated as yet unknown CNS-effects of this non-steroidal anti-inflammatory drug.

Adult↗
PubMed1989

[Full inpatient versus partial inpatient psychiatric after-care--a comparative retrospective study].

In a retrospective study 80 inpatients (Sociotherapy, Therapeutic Community) were compared to 160 outpatients (80 patient Day Clinic, 80 patients Night Clinic). With a mean treatment duration of 4-5 1/2 month a significant decrease was found for each group in the frequency and duration of further hospital admissions after end of therapy. Day and Night Clinic patients tending to a better outcome than the inpatients. Advantages of the Day and Night Clinic are seen e.g. in a higher degree of acceptance by patients and family doctors, disadvantages in the increased rate of suicide found in our sample.

Adult↗
PubMedDate not supplied

Cerebral chemosensory evoked potentials elicited by chemical stimulation of the human olfactory and respiratory nasal mucosa.

A stimulation method was employed by which chemosensory evoked potentials were recorded without tactile somatosensory contamination. The purpose of the study was to determine whether potential components evoked by stimulation of the chemoreceptors of the trigeminal nerve can be distinguished from those of the olfactory nerve. The stimulants (vanillin, phenylethyl alcohol, limonene, menthol, anethol, benzaldehyde, carbon dioxide and a mixture of vanillin and carbon dioxide) were presented in a randomized order to 13 volunteers. Chemosensory evoked potentials to substances which anosmics are unable to perceive (vanillin, phenylethyl alcohol) were termed olfactory evoked potentials; potentials to CO2, which effected no olfactory sensations were termed chemo-somatosensory potentials. Analysis of variance revealed that the different substances resulted in statistically significant changes in the amplitudes and latencies of the evoked potentials, and also in the subjective estimates of intensity. An increased excitation of the somatosensory system resulted in reduced latencies and enhanced amplitudes of the evoked potentials. Responses to the mixture of carbon dioxide and vanillin appeared significantly earlier (50-150 msec) than responses to either substance alone.

Adult↗
PubMedDate not supplied

Chemosensory event-related potentials in man: relation to olfactory and painful sensations elicited by nicotine.

The aim of this study was to investigate the topographical distribution of chemosensory event-related potentials in relation to stimulation with nicotine. The recognition thresholds of 3 different sensations elicited by nicotine (odor, burning, stinging) were determined. Subsequently, 3 concentrations of nicotine were applied which were just above mean threshold for each of the 3 sensations. Subjects rated the intensity of odor, burning, and stinging. Additionally, they tracked the time course of these sensations. Odor and stinging appeared immediately after stimulus onset. Burning started after several seconds. Intensity ratings of burning and stinging increased with rising stimulus concentrations, whereas the odorous sensation was strongest at medium concentrations. After low and medium stimuli largest mean amplitudes were parietally obtained, whereas following stimulation with the highest concentration, amplitudes peaked at Cz.

Adult↗