Showing papers by "University of Luxembourg published in 1987"

Antibodies to a 64,000 Mr human islet cell antigen precede the clinical onset of insulin-dependent diabetes

Abstract: Antibodies in sera from newly diagnosed insulin-dependent diabetes mellitus (IDDM) patients are directed to a human islet cell protein of relative molecular mass (Mr) 64,000. Since IDDM seems to develop after a prodromal period of beta-cell autoimmunity, this study has examined whether 64,000 Mr antibodies could be detected in 14 individuals who subsequently developed IDDM and five first degree relatives who have indications of altered beta-cell function. Sera were screened by immunoprecipitation on total detergent lysates of human islets and positive sera retested on membrane protein preparations. Antibodies to the 64,000 Mr membrane protein were consistently detected in 11/14 IDDM patients, and in all 5 first degree relatives. 10 IDDM patients were already positive in the first samples, obtained 4-91 mo before the clinical onset of IDDM, whereas 1 patient progressed to a high 64,000 Mr immunoreactivity, at a time where a commencement of a decline in beta-cell function was detected. 64,000 Mr antibodies were detected before islet cell cytoplasmic antibodies (ICCA) in two patients. In the control groups of 21 healthy individuals, 36 patients with diseases of the thyroid and 5 SLE patients, the 64,000 Mr antibodies were detected in only one individual, who was a healthy sibling to an IDDM patient. These results suggest that antibodies against the Mr 64,000 human islet protein are an early marker of beta-cell autoimmunity and may be useful to predict a later development of IDDM.

The effect of carrageenan-induced inflammation on the sensitivity of unmyelinated skin nociceptors in the rat.

Abstract: Carrageenan was subcutaneously injected in the area innervated by the saphenous nerve. Part of the mechano-heat sensitive C-fiber receptors (CHM) located inside or at the border of the inflamed area showed an enhanced responsiveness to heat stimulation (sensitization). Those CMH units exhibited spontaneous activity; their mechanical thresholds (von Frey) were higher than those of not spontaneously active fibers. None of the units located outside of the inflamed area displayed sensitization. The data reveal that only part of the CMH units in a uniformly inflamed skin area shows signs of sensitization. Our results are compared to those obtained in other inflammatory processes. The relation to inflammatory pain and to hyperalgesia and the contribution of endogenous substances to sensitization of CMH units are discussed.

Arachidonic acid metabolites and airway epithelium-dependent relaxant factor.

Abstract: Exogenous arachidonic acid (10(-8) to 10(-4) M) contracted epithelium-free guinea pig tracheal strips. Intact tracheal strips were contracted slightly by low concentrations of arachidonic acid (10(-8) to 10(-5) M), but higher concentrations relaxed them. In contrast, when tracheal strips were precontracted with histamine or carbachol, exogenous arachidonic acid had no effect on epithelium-free preparations but induced concentration-dependent (10(-8) to 10(-4) M) relaxation of intact tracheal strips. The effects of arachidonic acid both in epithelium-free and epithelium-containing trachea were blocked by either indomethacin (10(-6) M) or aspirin (10(-4) M). Studies on the effects of exogenous arachidonic acid, performed with a "sandwich protocol," demonstrated that the postulated airway epithelium-dependent relaxant factor released by an intact tracheal strip relaxes an adjacent epithelium-free strip in the same organ bath. This relaxation is antagonized by indomethacin suggesting the involvement of a cyclooxygenase product in this phenomenon. Comparison of concentration-response curves for contractile agonists in epithelium-free preparations and in one containing epithelium suggests the mobilization of airway epithelium-dependent relaxant factor by histamine but not by carbachol. The effects of cyclooxygenase and lipoxygenase inhibitors indicated that both relaxant and contractile arachidonic acid metabolites are generated by epithelial and nonepithelial cells alike in response to contractile agonists.

Nociceptor functions in intact skin and in neurogenic or non-neurogenic inflammation.

Abstract: Acute neurogenic or non-neurogenic inflammation was elicited in skin patches innervated by the saphenous nerve of anaesthetized Sprague Dawley rats. Lambda carrageenan was used to induce non-neurogenic inflammation, mustard oil (allyl-iso-thio-cyanate) or antidromic nerve stimulation to induce neurogenic inflammation. Antidromic nerve stimulation yielded plasma extravasation but no significant sensitization of unmyelinated nociceptor units. In contrast, mustard oil and carrageenan yielded plasma extravasation and sensitization of nociceptors, though carrageenan sensitized only part of them. Sensitization resulted in ongoing spike discharges and in a shift of response curves to lower temperatures when controlled radiant heat stimuli were applied to the receptive fields. Responses to mechanical stimuli with v. FREY hairs were not significantly altered. Effects of neurogenic and non-neurogenic inflammation on unmyelinated nociceptor units are compared.

Nonequilibrium Phase Transitions in Solid Catalysts for Oxidation

Abstract: Nonequilibrium phase transitions in oxidation catalysts follow either one of two distinct patterns. The system CuO/Cu2O—C3H6+O2 exemplifies the pattern of hysteresis. The influence of catalyst preparation on this pattern at 645 K is investigated as well as the influence of the presence of small amounts of Pd. The system Ni/NiO—H2+O2 exemplifies the pattern of coexistence of two phases of the active component, which in this case coexist by alternating in time.

Response of primary somatosensory cortical nociceptive neurons to noxious thermal stimulation applied to the face in trained monkeys

Abstract: Previous studies using anesthetized monkeys have reported a population of neurons in the primary somatosensory cortex (SI) that encode the intensity of noxious stimuli. However, no study has detailed the properties of these neurons in trained monkeys. In the present study, we examined the response properties of SI neurons in monkeys trained to detect noxious thermal stimuli applied to the face. Monkeys were trained to press a button that raised the temperature of a thermode from a baseline of 38°C to 45\", 46\", 47\" or 48°C (Tl). Tl was followed by an additional small temperature increase (T2) of l.O'C. If the monkey released the button within 2 set after T2 onset, the thermode temperature returned to 38°C and a juice reward was delivered. To date, 21 SI neurons have shown an increase in their discharge frequency to noxious thermal stimuli applied to the face. Twenty of these neurons were classified as WDR and one as a NS neuron. All of these neurons had receptive fields comprising 1 or 2 divisions of the trigeminal system. Twelve neurons increased their discharge frequency in a monotonic fashion to increasing thermal stimuli. The remainder of the neurons (9) responded to noxious thermal stimulation, but did not encode increases in the stimulus intensity. These data demonstrate that SI neurons respond to noxious thermal stimuli applied to the face of unanesthetized, trained monkeys. Furthermore, it appears that at least two populations of nociceptive SI neurons exist: one type that encodes increases in noxious thermal stimuli and may participate in the sensory-discriminative aspects of pain and another type that does not encode noxious thermal stimuli but may play a role in an arousal or alerting response.