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Biomedical subjects

G Guilbaud

Publications and source records attributed to G Guilbaud.

At least 145 records · Page 8Linked to original sources
PubMed1978

Serum proteins in heavily burnt patients.

Several serum proteins, such as prealbumin, protease inhibitors, immunoglobulins, metalloproteins and inflammatory glycoproteins were determined in the sera of heavily burnt patients by radial immunodiffusion. An increase of acute phase reactant glycoproteins (orsomucoid, haptoglobin, haemopexin, C-reactive protein), C3-complement, immunoglobulins, prealbumin and of the protease inhibitors (a1-antitrypsin, a2-macroglobulin) was found. For some proteins, such as prealbumin, haemopexin, immunoglobulins, this increase was preceeded by a decrease on days 3 to 5 post-burn. The time course of the increase was variable, faster for some patients and slower for others: orosomucoid, C-reactive protein, C3-complement reached peak values between days 6 and 8; immunoglobulins and hemopexin decreased then towards normal values. No significant increase was found for ceruloplasmin, transferrin, beta2-glycoprotein, a2-SH glycoprotein and GC-globulin. It is proposed that the selective overproduction of the above mentioned proteins may be related to the stimulation of acute-phase reactant protein synthesis by the liver as a result of tissue breakdown produced by the circulating proteases and especially by elastases and collagenases as was shown previously (Miskulin et al., 1978; Moati et al., 1978a).

Blood Proteins↗
PubMed1977

Responses of thoracic dorsal horn interneurons to cutaneous stimulation and to the administration of algogenic substances into the mesenteric artery in the spinal cat.

The effects of the injection of algogenic substances (bradykinin, acetylcholine) into the inferior mesenteric artery were studied at the thoracic level on 47 dorsal horn interneurons responding to cutaneous stimulation. Each unit was characterized by its electrophysiological properties and carefully located within the cord by extracellular injection of pontamine sky blue. Twenty cells, driven only by non-noxious cutaneous stimulation and mainly located in lamina IV, were not affected by the administration of algogenic substances. The activity of 25/27 cells, excited by both non-noxious and noxious cutaneous stimulation and mainly located in lamina V, was strongly modified by nociceptive visceral stimulation, induced by bradykinin and acetylcholine: 8/27 cells were activated, 14/27 were inhibited, 3/27 had a mixed inhibitory-excitatory response. From our study it clearly appears that nociceptive visceral messages only project on dorsal horn cells receiving noxious cutaneous afferents. Thus viscerosomatic convergence seems only to concern nociceptive messages; the existence of this kind of convergence reinforces the hypothesis suggested by several authors to explain referred pain from a neurophysiological point of view.

Acetylcholine↗
PubMed1977

Opiate antagonist, naloxone, strongly reduces analgesia induced by stimulation of a raphe nucleus (centralis inferior).

The analgesic effects obtained in the cat by central inferior raphe nucleus stimulation are greatly reduced by the administration of a specific opiate antagonist, naloxone. In 12 of 16 cats analgesia, tested by pinches applied on the 4 limbs or the tail, was totally abolished. Analgesia tested by considering the increase of the threshold of the jaw opening reflex was reduced to 44% of the initial value. These results emphasize the relation existing between morphine analgesia and analgesia induced by central stimulation. To try to explain the effects of naloxone, one may suppose that central stimulation releases an endogenous morphine-like substance such as enkephalin.

Analgesia↗
PubMed1977

Single units activities in ventral posterior and posterior group thalamic nuclei during nociceptive and non nociceptive stimulations in the cat.

The purpose of this study was to define, in hyperventilated and unanesthetized cats, the role of the posterior thalamic nuclei in pain mechanisms. Unit activities of these structures were compared to those of the ventro-posterior nucleus during non-noxious (touch, brushing) and noxious stimulations (pinches and intra-arterial injections of bradykinin into the limbs). 135 cells with somatic inputs and clear peripheral excitatory receptive field were studied. The cells driven by noxious stimulations were located in the posterior group nuclei as anatomically defined by Rinvik. These units, preferentially excited from contralateral receptive fields, were localized in POm, POl, suprageniculate nuclei, the magnocellular division of the medial geniculate body (Mgmc) and the ventral part of the lateral posterior nucleus. At this level two groups of units were found: those driven only by noxious stimulations and those driven by both noxious and non-noxious stimulations. On contrast, cells recorded at the levels of the VPm and VPl were not activated by noxious stimuli. These results emphasize the role of the posterior thalamic nuclei in pain processing.

Animals↗
PubMed1975

[A microphysiologic study of thalamic projection of the cat's dental pulp (author's transl)].

(1) A similar proportion of cells in the VPM (24.7%), MGmc (24%), CM (26.8%) and CL (28.6%) is activated by electrical stimulation of the cat's dental pulp. However the thresholds are very different, cells belonging to the first group of the VPM being often activated by stimulation below 0.1 V. (2) Pain seems to be the unique sensation evoked by pulpal stimulation. A first group of cells somatotopically localized in the VPM displays a primary type of response. These cells can also be activated from an oral or perioral field. This fact is reminiscent of referred pain phenomenon often encountered in the clinic. (3) A second group of cells scattered in the VPM and activated by pulpal stimulation displays a non-primary type of response. (4) Strong pinching of the skin activates some MGmc cells tonically. Response characteristics of the MGmc cells after pulpal stimulation are heterogeneojs. (5) CM cells activated by pulpal stimulation display long latency responses whose properties are similar to those obtained after somatic stimulation. However, the latency of responses are shorter after limb stimulation than after pulpal stimulation.

Animals↗
PubMed1975

Effects of the intra-arterial injection of bradykinin into the limbs, upon the activity of mesencephalic reticular units.

The changes in firing rate of mesencephalic reticular units after intra-arterial injection into the limbs of a potent nociceptive agent, bradykinin, were studied in cats (unanesthetized, immobilized with flaxedil and hyperventilated). 30 per cent of the d35 studied cells were affected, 56 per cent were excited, 23 per cent inhibited and 5 per cent had mixed effects. Among the 75 excited cells, the activation of 16 of them seemed to related to the arousa- processes (group A); for 56 cells the increase seemed dire-tly dependent on the nociceptive stimulation itself (group B). The changes of firing rate were repruducible; their latencies and durations were of the same order as the latencies and duration of the nociceptive reactions and painful sensation s, which have been obtained in animals and men after bradykinin injections. The modifications induced by bradykinin administration were suppressed by Ketamin and Thiopental.

Acoustic Stimulation↗
PubMed1975

Analgesia induced by electrical stimulation of the inferior centralis nucleus of the raphe in the cat.

In the cat, electrical stimulation of the inferior central nucleus of the raphe induces a powerful analgesia. This stimulation totally suppresses the behavioural reactions elicited by strong pinches applied to the tail or to the four limbs; it strongly modifies the threshold of the jaw opening reflex obtained by tooth pulp stimulation and considerably affects the behavioural reactions elicited by continuing such stimulation. The results can be considered as evidence that the mechanism of analgesia from the inferior raphe nucleus is similar to that already described in the dorsal raphe nucleus. The analgesia obtained by stimulation of raphe nuclei seems to be sustained by serotoninergic mechanisms and relationships between these are discussed. In preliminary experiments, analgesia induced by CI stimulation has been suppressed by administration of naloxone, a specific opiate antagonist.

Analgesia↗
PubMed1975

Descending inhibitory influences exerted by the brain stem upon the activities of dorsal horn lamina V cells induced by intra-arterial injection of bradykinin into the limbs.

1. In order to study descending influences of the brain stem upon the transmission of nociceptive messages at the spinal level, the activities of lumbar lamina V dorsal horn cells, induced by intra-arterial injection of brandykinin into the limbs, were recorded in unanaesthetized cats in both decerebrate and temporary spinal states (reversible cold block applied at the thoracic level). 2. In the decerebrate state, the intra-arterial injection of bradykinin had little or no effect. 3. During the reversible spinalization, the effects of bradykinin were revealed or considerably enhanced. As described in a previous study, in the C1-transected cat, three types of effects were encountered: excitatory, inhibiitory and mixed (inhibitory-excitatory). 4. These modifications observed after spinalization were generally associated with a large increase of the spontaneous firing rate. 5. These results emphasize, in the decerebrate cat, the importance of descending inhibitory controls exerted by the brain stem upon the transmission of nonciceptive messages at the spinal cord level.

Action Potentials↗