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Biomedical subjects

P Bjerring

Publications and source records attributed to P Bjerring.

At least 73 records · Page 4Linked to original sources
PubMed1992

The effect of quinidine on the analgesic effect of codeine.

We have studied the hypoalgesic effect of codeine (100 mg) after blocking the hepatic O-demethylation of codeine to morphine via the sparteine oxygenase (CYP2D6) by quinidine (200 mg). The study was performed in 16 extensive metabolizers of sparteine, using a double-blind, randomized, four-way, cross-over design. The treatments given at 3 h intervals during the four sessions were placebo/placebo, quinidine/placebo, placebo/codeine, and quinidine/codeine. We measured pinprick pain and pain tolerance thresholds to high energy argon laser stimuli before and 1, 2, and 3 h after codeine or placebo. After codeine and placebo, the peak plasma concentration of morphine was 6-62 (median 18) nmol.l-1. When quinidine pre-treatment was given, no morphine could be detected (less than 4 nmol.l-1) after codeine. The pin-prick pain thresholds were significantly increased after placebo/codeine, but not after quinidine/codeine compared with placebo/placebo. Both placebo/codeine and quinidine/codeine increased pain tolerance thresholds significantly. Quinidine/codeine and quinidine/placebo did not differ significantly for either pin-prick or tolerance pain thresholds. These results are compatible with local CYP2D6 mediated formation of morphine in the brain, not being blocked by quinidine. Alternatively, a hypoalgesic effect of quinidine might have confounded the results.

Adult↗
PubMed1992

Analgesic efficacy of immediate and sustained release paracetamol and plasma concentration of paracetamol. Double blind, placebo-controlled evaluation using painful laser stimulation.

The analgesic efficacy of single doses of immediate release paracetamol 500 mg and 1000 mg, sustained release paracetamol 2000 mg, and placebo was evaluated over a 12 h period in 10 healthy volunteers. The efficacy was related to the concurrent plasma concentrations of paracetamol. Experimental pain was induced by brief cutaneous application of argon laser pulses, and the analgesic effect was assessed as change in pricking pain threshold. Both 0.5 g and 1.0 g immediate release paracetamol had an analgesic effect superior to that of placebo from 1 to 5 h after administration. Peak analgesia was reached after 2 h. No difference was found in the analgesic effect of the two dosages. Sustained release paracetamol was not significantly superior to placebo at any time. The plasma concentration of paracetamol had peaked in the 1 h sample after of the immediate release tablet. The peak plasma concentration was reached 3-4 h after 2.0 g sustained release paracetamol. It is not known why the sustained release formulation did not produce any detectable analgesia. It is proposed, that the rate of increase in the plasma concentration of paracetamol might be important in the alleviation of acute (laser-induced) pain.

Acetaminophen↗
PubMed1992

Onset and duration of hypoalgesia of lidocaine spray applied to oral mucosa--a dose response study.

Lidocaine is often used as a topical analgesic prior to painful procedures performed in the oral cavity and upper airways. In this study the optimal time interval for performance of painful procedures in the oral cavity and the upper airways was determined by spraying lidocaine solution on the mucous membranes of the mouth with subsequent measurements of pain thresholds induced by argon-laser stimulation. Two different dosages (30 mg and 60 mg) of lidocaine spray were administered to the oral mucosa of the lower lip in healthy volunteers. Repeated measurements were performed until normal sensitivity returned after 15 min. Pain thresholds increased 62% after 30 mg lidocaine and 50% after 60 mg lidocaine (a non-significant difference). Thus repeated applications were found to be without any additional hypoalgesic effect. Maximal hypoalgesia was reached after 4 to 5 min. Complete analgesia was not obtained. The hypoalgesic effect lasted until 14 min, but painful procedures should be performed in the time interval 3-8 min after application.

Adult↗
PubMed1992

Erythema induced by organic solvents: in vivo evaluation of oxygenized and deoxygenized haemoglobin by reflectance spectroscopy.

OBJECTIVE: (i) using a new non-invasive technique capable of evaluating quantitatively and qualitatively the haemoglobin content of the skin (ii) to evaluate delipidization induced by organic solvents. PATIENTS: 11 Caucasians treated for 1 min in a randomized manner on the volar forearm with a mixture of chloroform/methanol (2:1) (CM) and ether/acetone (1:1) (EA) to delipidize the skin. METHOD: erythema was evaluated by computerized remittance spectroscopy immediately after delipidization and hourly for 2 h. RESULTS: only CM application induced subjectively observed and objectively quantified erythema. Erythema was related to a significant increase in oxygenized haemoglobin content due to dilatation of arterioles in the subpapillary plexus (P less than 0.01). The increased blood flow induced a significant (P less than 0.01) reduction in de-oxygenized haemoglobin in venous vessels immediately after CM application. CONCLUSION: short contact with certain potent solvent mixtures causes erythema, possibly due to massive lipid extraction and damage of the skin barrier. Using computerized remittance spectroscopy the visible erythema was composed of an increase in oxygenized haemoglobin and a relative decrease in deoxygenized haemoglobin.

Dermatitis, Irritant↗
PubMed1992

The analgesic effect of EMLA cream on facial skin. Quantitative evaluation using argon laser stimulation.

The hypoalgesic effect of EMLA cream (Eutectic Mixture of Local Anesthetics) applied for 5, 15, and 30 min on facial skin was evaluated. Hypoalgesia was assessed by changes in pain thresholds to brief argon laser stimuli 0, 2, 5, 10, 15, 20, 25, 30, 45, and 60 min after removal of EMLA cream. The local cutaneous vascular changes induced by EMLA cream was evaluated by Erythema Index determined by reflectance spectroscopy and by laser Doppler blood flowmetry. A large inter-individual variability in analgesic efficacy was observed. The volunteers could be divided into two groups, one group of 6 persons where EMLA induced analgesia or considerable hypoalgesia, and one group of 4 persons where EMLA had no or only slight hypoalgesic effect. This great variability should be considered when EMLA cream is used for facial application in the clinic. Differences in local blood flow probably contribute to the variability. Application of EMLA cream for 5 and 15 min did not change erythema of the skin, while 30 min of application caused minor blanching.

Adult↗
PubMed1992

Vertex potentials evoked by nociceptive laser stimulation of oral mucosa: a comparison of four stimulation paradigms.

A new method for quantitative assessment of oral mucosal nociception and analgesia has been introduced using vertex potentials elicited by nociceptive argon laser stimuli. Four different stimulation paradigms (long, random, warning, and self-triggered) were compared to determine which technique elicited the most reproducible vertex potentials. A warning stimulation paradigm applied on the tongue and hand elicited vertical potentials with smaller amplitudes, lowest intraindividual coefficient of variation (16.5% and 7.9%, respectively), and highest reproducibility. The latency of the major negative peak was not affected significantly by different stimulation paradigms. The high reproducibility of vertical potentials elicited by the warning stimulation may be ascribed to a standardized psychological state of the subjects.

Adult↗
PubMed1992

Hypoalgesic effect of EMLA and lidocaine gel applied on human oral mucosa: quantitative evaluation by sensory and pain thresholds to argon laser stimulation.

Sensory and pain thresholds to argon laser stimulation were used to evaluate the analgesic efficacy and duration of a eutectic mixture of local anesthetics (EMLA) and a 2% lidocaine gel applied topically on the oral mucosa. Application of EMLA for 2 min on the tongue and gingiva increased the pain thresholds by 92.8% and 63.4% respectively. Corresponding values for lidocaine gel were 53.6% and 21.9%. Standardized variation of the EMLA application period (2, 5, and 15 min) produced significantly different analgesic profiles on the tongue but not on the gingiva. Application of EMLA for 5 and 15 min on the tongue and for 2, 5, and 15 min on the gingiva increased the pain thresholds to a predefined analgesic level (2.15 W) for 2 to 25 min. The present experimental model for assessment of oral mucosa pain is suggested to be well-suited for investigations of intraoral analgesia.

Administration, Topical↗
PubMed1991

Comparison of four laser types for experimental pain stimulation on oral mucosa and hairy skin.

The use of different lasers for stimulation in human experimental pain research has provided a sensitive method for evaluation of thin nerve fiber functions. In this study, sensory and pain thresholds were compared to argon-, copper vapour-, Nd:YAG-, and CO2 laser stimulation on hairy skin and on oral mucosa. The influence on thresholds with respect to laser type, stimulation site, surface colour, and stimulus parameters (laser beam diameter and pulse duration) was investigated. Significant differences in thresholds between the four lasers were found on both surfaces; however, no significant differences existed between thresholds on the skin and on the tongue when the same laser was used. The observations imply that wavelength-dependent optical properties of the stimulated tissue influence on threshold determinations. Furthermore, the results indicate that temporal and spatial summation mechanisms may exist for laser induced warmth and pain perceptions. Laser stimulation may be a new tool for the investigation of origin and genesis of various orofacial pain syndromes.

Adult↗
PubMed1991

Involvement of thin afferents in carpal tunnel syndrome: evaluated quantitatively by argon laser stimulation.

The thin afferent nerves were tested quantitatively by determining the thresholds of warmth and pricking pain to argon laser stimulation and by measuring the brain potentials related to pricking pain. In 27 patients with electrophysiologically verified carpal tunnel syndrome these parameters were measured from fingers 3 and 5 on both hands. All patients had had sensory symptoms ranging from 3 months to 25 years. Both the thresholds were elevated (P less than 0.05) at finger 3 compared to measurements from finger 5, and compared to finger 3 in a group of 39 controls. Four patients with symptoms for more than 7 years had thresholds below the control values. The power of the pain-evoked brain potentials elicited from finger 3 was lower (P less than 0.05) compared to finger 5, and compared to the control group (P less than 0.01). No correlations were found between the measured parameters and the clinical electrophysiological investigation. The findings support previous assumptions that chronic low-force compressions cause impairment of intraneural microcirculation, and hence can affect the function of the thin afferents.

Adolescent↗
PubMed1991

Double-blind, placebo controlled comparison of paracetamol and paracetamol plus codeine--a quantitative evaluation by laser induced pain.

The aim of the present double-blind, placebo controlled, three-way cross over study was to evaluate the analgesic efficacy of single oral doses of paracetamol 1.0 g and paracetamol 1.0 g plus codeine 60 mg. Pain threshold and brain evoked potentials to laser stimulation were determined hourly for 6 h in 12 healthy volunteers. Pain threshold was significantly elevated compared to placebo 1 and 2 h after paracetamol ingestion. Paracetamol 1.0 g plus codeine 60 mg was superior to placebo 1 to 6 h after medication. Only at 1 and 2 h after ingestion the combined drug was better than paracetamol. The evoked potentials were significantly depressed compared to placebo 2 and 4 h after paracetamol. The combination of paracetamol and codeine was superior to placebo 1 to 6 h after ingestion. The potentials showed no difference between the two active drugs. The total analgesic effect (approximation of area under the time-efficacy curve), showed that the combined drug was superior to plain paracetamol. A higher incidence of adverse effects in 10 of the 12 subjects was observed after ingestion of the combined drug compared to plain paracetamol (1 of 12). Paracetamol appears to exert part of its action by a central effect. There was at least 1 h between the peak plasma concentration of paracetamol and the peak hypoalgesia.

Acetaminophen↗
PubMed1991

Serum aminoterminal propeptide of type III procollagen in psoriasis and psoriatic arthritis: relation to liver fibrosis and arthritis.

Levels of serum aminoterminal propeptide of type III procollagen were measured in 170 patients with psoriasis (49% with coexistent psoriatic arthritis) who had liver biopsies performed during or before treatment with methotrexate or, in some cases, with retinoids. Psoriasis patients with fibrosis or cirrhosis in their liver biopsy specimens had a significantly higher mean serum aminoterminal propeptide of type III procollagen than did patients without fibrosis and without arthritis. Only 4% of patients without cirrhosis or fibrosis and no arthritis had an elevated serum aminoterminal propeptide of type III procollagen. In contrast, 38% of patients with psoriatic arthritis had an increased aminoterminal propeptide of type III procollagen in the absence of detectable liver fibrosis. It is concluded that the number of liver biopsies performed on methotrexate-treated psoriasis patients with or without arthritis may be reduced to a minimum as long as serum aminoterminal propeptide of type III procollagen is normal. Increased serum aminoterminal propeptide of type III procollagen in the absence of arthritis is a strong indicator of liver fibrogenesis and suggests the need for liver biopsy to monitor possible methotrexate-induced toxicity. In patients with psoriatic arthritis an increased aminoterminal propeptide of type III procollagen may be related to the joint disease. Patients with psoriatic arthritis and increased levels of aminoterminal propeptide of type III procollagen should therefore follow the established guidelines for the use of methotrexate in psoriasis.

Alkaline Phosphatase↗
PubMed1991

Subhypnotic doses of thiopentone and propofol cause analgesia to experimentally induced acute pain.

Subhypnotic doses of thiopentone are considered to have a hyperalgesic effect, while propofol has a hypoalgesic effect. We investigated the effect of these drugs on the nociceptive system by measuring the pain threshold to laser stimulation and the pain evoked potential (power and latency). Nineteen patients (ASA group I) participated. Twelve patients received thiopentone 0.5 mg kg-1 and propofol 0.25 mg kg-1 in random order separated by an interval of 14 h, and seven patients received saline. Immediately after the injection of both agents, the pain threshold was increased significantly (P less than 0.001) and the amplitude of the evoked potential was reduced significantly (P less than 0.05), while the latency of the evoked potential remained constant. It is concluded that, in subhypnotic doses, both thiopentone and propofol decrease the acute pain evoked by argon laser stimulation.

Acute Disease↗
PubMed1991

The effect of hypnotically induced emotional states on brain potentials evoked by painful argon laser stimulation.

The relationship between pain perception and emotional states is well known. However, the nature of this relationship and how different emotional states affect sensory and cognitive dimensions of pain remains uncertain. Results from experimental investigations are often contradictory, which may be due to methodological difficulties in inducing pain and monitoring physiological responses. In addition, most studies have focused on a single emotion, and data on the relative effects of different emotional states are lacking. In the present study we attempted to eliminate some of these methodological problems. Laser evoked potentials were used as a quantitative correlate to pain perception and were measured in 12 highly hypnotically susceptible subjects during seven conditions: (a) a prehypnotic baseline condition; (b) a neutral hypnotic control condition; (c-e) hypnotically recalled anger, fear, and depression in randomized order; (f) a hypnotically recalled happy condition, and (g) a posthypnotic awake control condition. The pain evoked potentials were significantly decreased in the angry condition and significantly increased in the depressed condition compared with baseline. No differences could be detected for either the happy or the fear-related condition compared with the baseline or neutral hypnotic condition. A significant positive correlation between the subjective intensity of depression and the increase in evoked potentials was found, but none for the other three emotions. The results support earlier findings that clinical depression is related to increased pain perception, and findings that the expression of anger can inhibit the experience of pain.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

A comparison of the hypoalgesic effect of paracetamol in slow-release and plain tablets on laser-induced pain.

1. In a double-blind, three way, cross-over study 15 volunteers received plain paracetamol tablets 1000 mg every 6th hour, paracetamol slow-release tablets 2000 mg every 12th hour, and placebo. Steady state conditions were established over a 5 day period preceding each test session. 2. Plain paracetamol was given twice in the 12h test session, initially and after 6 h, and the slow-release formulation was given once at the start of the session. 3. Hypoalgesia, measured by experimentally laser-induced pain (pain threshold), and plasma concentrations of paracetamol were measured hourly for 12 h. 4. Both formulations of paracetamol were significantly superior (P = 0.0003) to placebo, but not difference in analgesic efficacy was found between the two regimens.

Acetaminophen↗
PubMed1991

Monocyte chemotactic activity in sera after hypnotically induced emotional states.

In a number of studies it has been shown that psychological factors in general and specifically emotional factors can be correlated to changes in immunological function and defence mechanisms. Although the mediating pathways between the central nervous system and the immune system still remain unclear, it is known that some of the 'classical stress hormones' such as cortisol and catecholamines have modulatory effects on different immunological parameters. In this investigation we wished to study the effect of brief hypnotically induced emotional states on monocyte chemotaxis and endocrinological parameters. Eleven highly hypnotically susceptible volunteers were, while in a deep trance, given suggestions to re-experience earlier life experiences involving intense anger and depression in random order. Before concluding hypnosis subjects were given suggestions to re-experience a feeling of happiness and well-being. Monocyte chemotactic activity in sera and serum levels of cortisol, as well as venous plasma levels of the catecholamines epinephrine, norepinephrine, DOPA and DOPAC, were measured before hypnosis, after each emotional state and immediately after hypnosis. The results showed a significant differences (P less than 0.02) in chemotactic activity between the angry and the depressed emotional states, the depressed state exhibiting a decreased chemotactic index compared with the angry state. Chemotactic index after the happy relaxed emotional state also showed a significant (P less than 0.01) increase compared with both chemotactic index before hypnosis and chemotactic activity after the angry and depressed state. Though there were significant differences between emotions and between emotions and the before-hypnosis-condition, no clear-cut significant differences between the emotional states of anger and depression could be detected for serum cortisol levels and catecholamine plasma levels. Significant positive correlations (P less than 0.01) for differences in chemotactic activity and differences in plasma DOPA levels between emotional states was found. When investigated in vitro, DOPA did not in itself exhibit monocyte chemotactic properties. No other significant correlations between differences in chemotactic activity and other endocrinological parameters could be detected. Soluble interleukin-2 receptors in serum were also measured. No significant differences were found.

Anger↗
PubMed1991

A quantitative double-blind evaluation of the antinociceptive effects of perineurally administered morphine compared with lidocaine.

In two double-blind, placebo-controlled investigations, morphine and lidocaine were administered perineurally to the ulnar nerve. Thresholds (warmth and pain) and pain-evoked brain potentials (amplitude and latency) to argon laser stimulation were measured up to 120 min after the injection. Hypalgesia to laser pain was detected 15 min after the injection of morphine and 5 min after the injection of lidocaine. The duration of hypalgesia and analgesia was less than 15 min for morphine and 85 min for the lidocaine injection. Both morphine and lidocaine increased the latency of the brain potentials, which indicates that the same blocking mechanisms could be involved. Pin-prick analgesia was obtained 5 min after the injection of lidocaine, but 15-30 min elapsed before the laser pain was inhibited maximally. Laser pulses can activate larger skin areas than needle pricks, indicating that a central summation of the activity from many cutaneous nociceptors is important in order to obtain a reliable indicator of adequate analgesia.

Adult↗
PubMed1991

Hypoalgesia following intrathecal morphine: a segmental dependent effect.

The onset phase of hypoalgesia, following intrathecal morphine, was assessed by experimental argon laser-induced pain. A dose of 0.4 mg morphine was injected pre-operatively at the L3-L4 level into nine patients. The thresholds to laser-induced pain and pain-evoked brain potentials were monitored for 2 h at the S1, L1, and C7 dermatomes. Hypoalgesia was detected at the S1 and L1 dermatomes after 5 and 15 min, respectively. No hypoalgesic effect was found at C7. This indicates that hypoalgesia was caused predominantly by segmental spinal mechanisms during the onset phase, and not by a general widespread effect. No latency changes (conduction delay) of the brain potentials evoked from the hypoalgesic dermatomes were found. Cutaneous pain, induced experimentally by laser stimulation, has the advantage of being quantitative and is useful to assess the onset and the segmental spread of hypoalgesia.

Adult↗