Biomedical subjects

P Mohammadian

Publications and source records attributed to P Mohammadian.

8 recordsLinked to original sources

PubMed2001

Peripheral levels of inflammatory mediators in migraineurs during headache-free periods.

OBJECTIVES: The present study investigated the peripheral inflammatory changes of the trigeminovascular system by measuring the inflammatory mediators leukotriene B4 (LTB(4)), prostaglandin E2 (PGE(2)), and thromboxane B2 (TXB(2)) in the nasal fluid, as well as saliva, of patients with migraine. BACKGROUND: Migraine has been hypothesized to be as a result of changes in the peripheral or central nervous system or both. It is still unclear whether peripheral changes in the trigeminovascular system are involved in the pathogenesis of migraine. METHODS: Participants were 18 subjects, 9 patients with migraine and 9 controls, matched for age and sex. Each subject took part in one experimental session during which nasal lavage fluid and saliva samples were collected. These samples were analyzed by competitive enzyme immunoassay using goat anti-rabbit polyclonal antibody. RESULTS: With the exception of TXB(2), correlational analyses indicated good correlations between results obtained using nasal lavage or saliva (LTB(4), r(18) = 0.91; PGE(2), r(18) = 0.95). When comparing inflammatory mediators measured in controls and migraineurs, the LTB(4) level was significantly lower in migraineurs, while no differences were found for PGE(2) and TXB(2). CONCLUSIONS: The study demonstrated that nasal lavage, a noninvasive method, can be easily used for investigations of pathophysiological mechanisms of migraine. In addition, the results may indicate that there is no peripheral trigeminal sensitization in the headache-free period of migraineurs compared with controls when PGE(2), LTB(4), and TXB(2) in saliva and nasal lavage samples are measured.

Adult↗

PubMed1999

Experimentally induced nasal irritation.

The aim of this study was to develop a method that is suited for the induction of nasal irritation. For this purpose inflammatory responses were analysed after challenging the nasal mucosa with experimentally induced cold, dry air (8 l/min, 22 degrees C, 20 %RH). To assess inflammatory effects we determined inflammatory mediators (prostaglandin E2 [PGE2], thromboxane B2 TXB2[, peptide leukotrienes pLT: LTC4, LTD4, LTE4[) in nasal lavage fluid which was sampled before, immediately after suprathreshold stimulation, and one hour after termination of the stimulation. In addition, subjects estimated the intensity of pain during the stimulation. Cold, dry air produced strong painful sensations which increased throughout the stimulation period. A significant increase of the inflammatory mediator pLT was observed after stimulation; mean concentrations of PGE2 and TXB2 also showed a tendency to increase. One hour after termination of the stimulation the concentration of these inflammatory mediators returned to baseline which indicates the reversibility of the effects of nasal irritation. These data suggest, that this model may be a useful tool in investigations of mucosal irritation as, for example, induced by environmental agents.

Adult↗

PubMed1998

Capsaicin-induced impairment of tactile spatial discrimination ability in man: indirect evidence for increased receptive fields in human nervous system.

The effects of capsaicin was investigated on vibration detection thresholds, touch detection thresholds, mechanically-evoked pain thresholds, two-point discrimination ability, and ability to detect roughness of different stimulation surfaces in the left hands of human volunteers in a double-blind controlled study. Capsaicin cream induced allodynia to mechanical stimulation in both primary and secondary area of hyperalgesia. Capsaicin impaired two-point discrimination ability, and reduced the ability to detect differences of the roughness of various stimulation surfaces only within the capsaicin treated area (area of primary hyperalgesia). These changes were not seen after placebo cream. We conclude that experimental inflammation and related pain impairs spatial discrimination ability which could be due to increases in the receptive fields of neurons in the peripheral and central nervous system (CNS).

Adult↗

PubMed1998

Correlation between local vascular and sensory changes following tissue inflammation induced by repetitive application of topical capsaicin.

The aim of the present study was to investigate local vascular and sensory changes and their correlation in order to obtain a better understanding of the mechanisms of allodynia, hyperalgesia and vascular changes following tissue inflammation induced by repetitive application of capsaicin cream. This type of application was utilized as a controlled model of inflammation which was altered in intensity due to its repetitive applicability. Ten healthy volunteers participated in two experiments separated by at least five days. Each experiment consisted of a baseline session followed by five additional sessions. Before these sessions either 1.5 g capsaicin (1%) or placebo cream was applied to the volar site of the forearm for 15 min. The areas of stroking allodynia and pin-prick hyperalgesia were mapped and the intensity of spontaneous pain (VAS) was assessed after each application of the cream. In addition, the visible flare, temperature (IR-Thermography), and blood- flow (Laser-Doppler) were measured. The first application of capsaicin was perceived as painful; it induced both secondary hyperalgesia and allodynia. Compared to placebo, the first application of capsaicin cream also resulted in an increased blood-flow, elevated temperature and visible flare. The highest values of these sensory and vascular parameters were reached after the third application. A direct correlation between visible flare, secondary mechanical hyperalgesia and allodynia following repetitive application of capsaicin indicates that both common central and peripheral mechanisms were involved in these changes.

Administration, Topical↗

PubMed1998

Handedness is a determining factor in lateralized olfactory discrimination.

The study aimed to re-investigate differences in olfactory thresholds and odor discrimination between the left and right sides in relation to the handedness of healthy subjects. Twenty left- and 20 right-handers participated; all were in excellent health with no indication of any major nasal or health problems, and all were non-smokers. The two groups were comparable in terms of sex and age (left-handers: 11 women, 9 men, median age 25 years; right-handers: 9 women, 11 men, median age 26 years). Odor thresholds did not differ in relation to handedness. However, in the odor discrimination task the left-handers performed significantly better at the left side compared with the right nostril; this pattern was reversed in the right-handers. The data indicate that, similar to other sensory systems, higher olfactory functions exhibit a certain degree of lateralization.

Adult↗

PubMed1997

Comparison of the antinociception produced by two oral formulations of ibuprofen: ibuprofen effervescent vs ibuprofen tablets.

OBJECTIVE: The aim of this study was to compare the dose-related effects of both ibuprofen tablets and ibuprofen effervescent [placebo, 400 and 800 mg ibuprofen (Aktren)] on phasic pain. PATIENTS: Twenty volunteers participated in this randomized, double-dummy, fivefold crossover study. METHODS: Measurements were obtained before and 15, 60 and 240 min after drug administration. Pain was produced by CO2 pulses applied to the left nostril. Subjects rated the intensity of the painful stimuli by means of a visual analogue scale. In addition, chemosomatosensory event-related potentials were recorded. RESULTS: In line with previous work, ibuprofen produced a dose-related decrease in pain-related potential amplitudes P1N1, indicating its antinociceptive effects. Higher plasma concentrations of ibuprofen were reached 15-40 min after administration of the effervescent while ibuprofen tablets had a tmax 60-90 min after administration. In addition, 60 min after intake of the effervescent a prolongation of the latencies of the potentials was observed, possibly reflecting superior antinociceptive properties when compared to ibuprofen tablets. In addition, the effervescent appeared to have more consistent effects on intensity estimates compared to ibuprofen tablets.

Administration, Oral↗

PubMed1995

Effects of flurbiprofen enantiomers on pain-related chemo-somatosensory evoked potentials in human subjects.

1. The aim of the study was to investigate the analgesic effects of flurbiprofen enantiomers using an experimental pain model based on both chemo-somatosensory event-related potentials (CSSERP) and subjective pain ratings. 2. Healthy female volunteers (n = 16, age 23-36 years) participated in a placebo-controlled, randomised, double-blind, four-way crossover study. Single doses of (S)-flurbiprofen (50 mg), (R)-flurbiprofen (50 and 100 mg) and placebo were administered orally. Measurements were taken before and 2 h after administration of the medications. During each measurement, 32 painful stimuli of gaseous carbon dioxide (200 ms duration, interval approximately 30 s) of two concentrations (60 and 65% CO2 v/v) were applied to the right nostril. EEG was recorded from five positions and CSSERP were obtained in response to the painful CO2- stimuli. Additionally, subjects rated the perceived intensity of the painful stimuli by means of a visual analogue scale (VAS). 3. The CSSERP-amplitude P2, a measure of analgesic effect, decreased after administration of both (R)- and (S)-flurbiprofen, while it increased after placebo. This was statistically significant at recording positions C4 (P < 0.01) and Fz (P < 0.05). The analgesia-related decreases in evoked potential produced by (R)-flurbiprofen were dose-dependent. Comparing similar doses of (R)- and (S)-flurbiprofen, the decrease in CSSERP-amplitudes produced by the (S)-enantiomer was somewhat more pronounced, indicating a higher analgesic potency. 4. The present data indicate that both enantiomers of flurbiprofen produce analgesic effects. Since (R)-flurbiprofen caused only little toxicity in rats as compared with the (S)-enantiomer or the racemic compound, a reduction of the quantitatively most important side effects in the gastrointestinal tract might be achieved by employing (R)-flurbiprofen in pain therapy.

Adult↗

PubMed1995

Effects of azapropazone on pain-related brain activity in human subjects.

1. The dose-related effects of azapropazone on (i) event-related and spontaneous EEG-activity and (ii) the subjects' pain ratings were investigated using an experimental human pain model based on both chemo-somatosensory event-related potentials (CSSERP) and subjects' pain ratings. 2. Healthy subjects (n = 20) participated in a placebo-controlled, randomized, double-blind, four-way cross-over study. Single doses of azapropazone (300 mg, 600 mg and 1200 mg) and placebo were administered intravenously. Each experiment consisted of five sessions (before and 1, 2, 4 and 8 h after administration of the medication). Each session lasted for approximately 40 min. In the first 20 min, pain was induced by short CO2-stimuli presented to the right nostril (phasic pain; interstimulus interval 30 s) and EEG was recorded from five positions. CSSERPs were obtained in response to painful CO2-stimuli. In the following 20 min period, tonic pain was induced by a constant stream of dry air introduced in the left nostril. Subjects rated the intensity of both phasic and tonic pain by means of a visual analogue scale. Additionally, a frequency analysis of the spontaneous EEG was performed. 3. Azapropazone reduced the pain-related CSSERP-amplitudes at frontal and parietal recording positions. This topographical pattern was observed in previous studies with opioids, while NSAIDs such as flurbiprofen and ketoprofen exerted effects at frontal and central positions. In contrast to other NSAIDs, administration of azapropazone resulted in a reduction of the frequency bands alpha 1, delta and theta of the spontaneous EEG. At the subjective level, analgesic effects of azapropazone were observed in the ratings of tonic pain. 4. Analgesic properties of azapropazone were demonstrated in man. The topographical pattern of the changes in the CSSERPs and the effects on EEG background activity suggest a central component of the analgesic action of azapropazone.

Adult↗