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Biomedical subjects

P Kemppainen

Publications and source records attributed to P Kemppainen.

At least 37 records · Page 2Linked to original sources
PubMed1993

Effects of jaw clenching, jaw movement and static jaw position on facial skin sensitivity to non-painful electrical stimulation in man.

The effects of isometric jaw clenching, static jaw position and jaw movement on electrically evoked perception thresholds of the facial skin of the mental region were studied in healthy human subjects. Exercise consisted of brief (1 s) isometric contractions of jaw-closing muscles against a static load (30% of the maximum force), or continuous jaw movements at two different frequencies (1 and 3 Hz). A visual cue was used to indicate the start and end of the isometric exercise (duration 1 s.). Isometric jaw clenching induced a significant elevation of perception thresholds in the skin of the lower jaw just before and during the early electromyographic response of the jaw-closing muscles. This elevation was attenuated before the end of the exercise. Corresponding thresholds evoked by electrical stimulation applied to the dorsum of the hand were not changed by isometric jaw clenching. Changes in static jaw position did not have any effect on detection thresholds. Continuous 'masticatory-like' jaw movements produced a velocity-dependent reduction of sensitivity in the facial skin. The suppression was significantly stronger than that produced by isometric jaw exercise. An imagined isometric biting exercise, which presumably activated the supplementary motor cortex, did not cause any threshold elevations. The results indicate that isometric jaw clenching as well as cyclical jaw movements produce segmentally a phasic, rapidly attenuating masking of facial skin sensitivity.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Maximal contraction force and endurance of human jaw-closing muscles in isometric clenching.

Maximal unilateral bite force and endurance times from maximal bite force to the 75% and 50% levels of maximal values were recorded for 13 men and 15 women with bite openings of 10 and 14 mm. Measurements were made both from right and left molar regions and from the incisal region. Bite force values were significantly higher than previously measured in endurance tests by devices with unilateral housings. Men achieved greater bite force than women in the molar region in every trial. The general assumption that women's muscles are superior to those of men in static endurance when both are working at the same percentage of maximal voluntary contraction was not supported by this work for jaw-closing muscles. The endurance times to 75% and 50% levels of maximal bite force were shorter than could be expected from previous reports, and endurance times to the 50% level were even shorter than those reported for muscles of limbs.

Adult↗
PubMed1992

Lowered cutaneous sensitivity to nonpainful electrical stimulation during isometric exercise in humans.

The effect of isometric exercise on cutaneous sensitivity to nonpainful electric stimulation was studied in human subjects. The exercises consisted of brief (duration: 1-10 s) palmar flexions of the hand or foot against varying loads (10-30% of the maximal force). A visual "go" cue was used to indicate the start and end of the exercise. Isometric hand exercise produced a load-dependent increase of electrotactile thresholds of the fingers. The threshold elevation was rapidly attenuated with prolonged duration of the exercise. The hand exercise-induced threshold elevation was of equal magnitude in the glabrous and hairy skin of the fingers. Thresholds were not changed for the hand contralateral to the exercising hand. Passive static pressure of the hand did not produce threshold changes, whereas activation of afferent inhibition by a vibrotactile stimulus (100 Hz, 0.1 mm) did produce a significant threshold elevation. Exercise-induced threshold elevation was also significant immediately prior to the EMG response of the arm but not at the time of the visual "go" signal, or before it. The threshold increase found during the EMG response was not significantly stronger than that found prior to the EMG response. These results suggest that isometric exercise load-dependently produces a phasic, rapidly attenuating increase in cutaneous tactile thresholds in the exercising limb but not multisegmentally. Corollary efferent barrage from motor to sensory structures of the brain could be underlying the threshold changes produced by isometric exercise, whereas afferent inhibitory mechanisms seem to have only a minor role.

Adult↗
PubMed1991

Modulation of skin sensitivity by dynamic and isometric exercise in man.

The effect of dynamic cycle ergometer exercise and isometric leg exercise on skin sensitivity was studied in man. Exercise was performed at different loads. Cutaneous sensitivity to innocuous and noxious thermal stimuli was tested using a contact thermostimulator and sensitivity to tactile stimuli was tested using electrical stimuli. During isometric exercise a segmental (the exercising limb), but not a multisegmental, phasic decrease of cutaneous thermal sensitivity to innocuous stimuli was found. At the isometric forces used the effect on tactile and heat pain sensitivity was not significant. During dynamic exercise a multisegmental, load-dependent decrease of sensitivity in all tested sensory modalities was found and this attenuation disappeared gradually after the end of exercise. In contrast to isometric exercise, the decrease of sensitivity produced by dynamic exercise was most evident in tactile sensitivity. The size of the stimulus area (7.9 vs 11.8 cm2) did not have a significant effect on the magnitude of the exercise-induced decrease of cutaneous thermal sensitivity to innocuous stimuli. It was concluded that underlying the modulation of skin sensitivity by dynamic and isometric exercise were mechanisms that were different, at least to a small extent. Isometric exercise produced a segmental modulation of skin sensitivity due to central neuronal mechanisms, independent of exercise-induced stress. Exercise-induced stress could have caused the modulation of skin sensitivity by dynamic exercise.

Adult↗
PubMed1991

The effects of medetomidine, an alpha-2-adrenoceptor agonist, and cocaine on the tooth pulp-evoked jaw-opening reflex in cat.

In the pentobarbitone-anesthetized cat, the threshold of the tooth pulp-elicited jaw-opening reflex was elevated in a dose-dependent way (30-100 micrograms/kg, IP) following the administration of medetomidine, an alpha-2-adrenoceptor agonist. This elevation was significantly reduced by atipamezole (1 mg/kg, IP), an alpha-2-adrenoceptor antagonist. The inhibitory interaction between two successive dental stimuli applied to the same tooth (in-field inhibition) was suppressed by a lower dose of medetomidine (30 micrograms/kg) than the threshold elevation to single electrical pulses (55 micrograms/kg). Only the highest dose of medetomidine used (100 micrograms/kg) significantly influenced the temporally facilitated (in-field facilitation) response. In comparison, cocaine, a nonspecific monoaminergic agent, did not produce a significant threshold elevation of the tooth pulp-elicited jaw-opening reflex (1-25 mg/kg, IP). It is concluded that medetomidine, through an action on alpha-2-adrenoceptors, can suppress a predominantly nociceptive trigeminal reflex in anesthetized cats. The threshold evoked by single electric pulses, in-field inhibition, and in-field facilitation display differential sensitivities to medetomidine effects.

Adrenergic alpha-Agonists↗
PubMed1991

Effect of systemic medetomidine, an alpha 2 adrenoceptor agonist, on experimental pain in humans.

The effect of systemic (intravenous) medetomidine, an alpha-2 adrenoceptor agonist, on pain thresholds was studied in healthy human subjects (n = 6). Medetomidine produced a dose-dependent (cumulative doses: 25 and 50 micrograms) sedative effect evaluated by visual analog scale. Also, a dose-dependent decrease of blood pressure but not of heart rate was seen after administration of medetomidine. Pain threshold to electric stimulation of the tooth pulp and cutaneous heat pain threshold were uninfluenced by medetomidine. An index of cutaneous thermal sensitivity to innocuous stimuli, the width of the thermoneutral zone, also was uninfluenced by medetomidine. Medetomidine produced a significant attenuation of the affective-motivational component (unpleasantness) of tourniquet-induced ischemic pain, whereas the sensory-discriminative component (pain magnitude estimate) of the ischemic pain was not attenuated. The results suggest that systemic medetomidine alone at subanesthetic but sedative and hypotensive doses does not significantly influence the intensity and thresholds of experimental pain, whereas the affective-motivational component of pain can be attenuated.

Adrenergic alpha-Agonists↗
PubMed1990

Dexamethasone attenuates exercise-induced dental analgesia in man.

The effect of dexamethasone on exercise-induced adrenocorticotropin (ACTH) secretion and dental analgesia was studied in healthy human subjects. Different levels of exercise (100-200 W) were produced by a cycle ergometer. Dental pain thresholds were tested with a constant current stimulator. Dental pain thresholds were elevated with increasing work loads, and the elevation was still significant 30 min after the end of the exercise. Dexamethasone produced a significant reversal of exercise-induced pain threshold elevations concomitantly with the suppression of exercise-induced ACTH release. The results suggest that the corticotropin releasing factor-ACTH axis is involved in the exercise-induced analgesia.

Adrenocorticotropic Hormone↗
PubMed1990

Experimentally induced ischemic pain and so-called diaphase fix current.

It has been claimed that the diadynamic currents have either analgesic or other beneficial effects during the treatment of various painful musculoskeletal disorders. However, no experimental or controlled clinical results have been presented to support these claims. In this study, the possible analgesic effect of the DF (diaphase fix)-current on experimental pain was evaluated. An ischemia was experimentally induced in the left arm of five healthy male volunteers by a modified submaximal effort tourniquet test. Each subject had two consecutive ten minute periods of ischemia, one with and another without the DF-current. The subjective pain responses to the ischemia were measured by the visual analogue scale. The DF-current did not cause any marked decrease in the mean pain responses in this experiment. This experiment did not support the idea of using the diadynamic currents in alleviating musculoskeletal pain.

Adult↗
PubMed1987

Human pain thresholds after the application of lypressin, a vasopressin analogue.

Recent animal studies indicate that vasopressin has analgetic properties. The aim of this study was to find out if lypressin, a vasopressin analogue, produces analgesia in man. The effect of i.n. lypressin (5 and 10 I.U.) on experimental pain was tested in healthy humans. The lower dose proved high enough to produce a significant antidiuretic effect. Lypressin did not have any marked analgetic effect at these doses either on ischaemic, cutaneous thermal, or dental pain. The results indicate that lypressin cannot be used for pain relief in man at doses low enough not to produce a hazardous water retention.

Administration, Intranasal↗
PubMed1987

Pain and stress: correlation of stress hormone release to pain modulation in man.

The contribution of stress-induced and opioid-dependent mechanisms to the modulation of experimental pain was studied in man under different conditions. The contribution of these mechanisms to the possible attenuation of acute cardiac pain in human patients was also studied. According to the present series of investigations, stress-induced mechanisms might be involved in the modulation of pain caused by physical exercise but not by concurrent subacute pain or transcutaneous nerve stimulation. The lack of any negative correlation between the pain intensity and the release of stress hormones indicates that stress mechanisms do not attenuate acute ischaemic pain of the cardiac origin. The use of an opioid-antagonist, naloxone, and the measurement of plasma levels of beta-endorphin did not reveal any contribution of endogenous opinoids to pain modulation in the current study.

Coronary Disease↗
PubMed1986

Elevation of dental pain threshold induced in man by physical exercise is not reversed by cyproheptadine-mediated suppression of growth hormone release.

The effect of cyproheptadine on growth hormone (GH) secretion and dental pain threshold elevation during physical exercise was studied in healthy human subjects. Different levels of exercise (200-300 W) were produced by a cycle-ergometer. Dental pain thresholds were tested with a constant current pulp tester. In all 6 subjects dental pain thresholds and the heart rate were increased with increasing work load. Cyproheptadine did not have any significant effect on dental pain threshold elevations, although it suppressed the exercise-induced GH release. The results indicate that the exercise-induced dental pain threshold elevation is not based on GH-related stress mechanisms, since cyproheptadine did not reverse the pain threshold elevation.

Adult↗
PubMed1985

Modification of dental pain and cutaneous thermal sensitivity by physical exercise in man.

The effect of physical exercise on dental pain thresholds, the release of pituitary stress hormones and thermal sensitivity of skin was tested in healthy human subjects. Different levels of exercise (100-300 W) at different pedal frequencies were produced by a cycle ergometer. Thermal limen (the interval between warm and cool thresholds) determined from glabrous hand, hairy forearm and leg was used as a parameter of thermal sensitivity. In all subjects the heart rate and blood pressure were increased with increasing work load. Dental pain thresholds were elevated at high work loads with a concomitant activation of pituitary stress hormone (especially growth hormone) release. Thermal limens at all 3 sites were increased work load, too, independent of the pedal frequency. The increase of thermal limen was most marked in the leg and least in the glabrous hand. The results indicate that physical exercise produces a non-segmental, load-dependent decrease of pain and thermal sensitivity with a concomitant activation of pituitary stress mechanisms. The magnitude of modification varies with skin region. Activation of inhibitory mechanisms at spinal levels via muscle and proprioceptive afferents, in a way suggested by the gate control theory of pain mechanisms, seems to have only a minor, if any, contribution to the present findings, since a higher pedal frequency did not produce a more marked decrease of sensitivity.

Adrenocorticotropic Hormone↗
PubMed1985

The effect of tourniquet-induced ischemia on somatically evoked cerebral magnetic fields in man.

We recorded somatically evoked magnetic fields (SEFs) during tourniquet-induced ischemia in healthy humans. The subjective intensities of the stimuli decreased earlier and more clearly than the amplitudes of the SEF deflections peaking at 60-80 ms. Mixed nerve and sensory nerve responses behaved differently during ischemia. The results indicate that these SEF deflections are transmitted through thick myelinated fibers. Muscle afferents might contribute considerably to mixed nerve SEFs.

Adult↗
PubMed1983

Modification of human dental pain thresholds by conditioning vibrotactile stimulation at high frequency.

The effects of vibrotactile stimulation on dental pain thresholds were studied in 6 healthy human volunteers. Mechanoreceptive afferents were activated with conditioning sinusoidal vibration at 240 and 100 Hz. Significant dental pain threshold elevations were observed only when the conditioning stimulus was applied at high intensity ipsilaterally to the tested tooth. The present study suggests that the dental pain threshold elevation during high-frequency vibratory stimulation is based on the total number of impulses generated in mechanoreceptive afferents.

Adult↗
PubMed1982

Ischemic pain nonsegmentally produces a predominant reduction of pain and thermal sensitivity in man: a selective role for endogenous opioids.

Ischemic pain was produced by a blood pressure cuff placed to the arm of healthy human subjects for 15 min which produced a mean pain score of 59% (visual analogue scale). Ischemia induced a significant dental pain threshold elevation (mean 67%) and 2 mg of naloxone did not reduce it. Thermal sensitivity of the upper lip had a tendency to reduction during ischemia and 2 mg of naloxone reduced this effect. Tactile thresholds in the forehead or in the contralateral arm were not markedly elevated. Neither ACTH nor prolactin level in the plasma was related to the dental pain threshold elevation during ischemia. The findings of the present study suggest that ischemic pain nonsegmentally produces a predominant inhibition of responses to thin afferents. Endogenous opioids may markedly contribute to the reduction of thermal sensitivity induced by ischemia, but their contribution to dental pain threshold elevations seems to be less important. Stress or other adenohypophyseal mechanisms involving the release of ACTH or prolactin do not explain the effects of ischemia found in the present study.

Adrenocorticotropic Hormone↗