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Biomedical subjects

C Gros

Publications and source records attributed to C Gros.

At least 235 records · Page 13Linked to original sources
PubMedDate not supplied

The endogenous tripeptide Tyr-Gly-Gly as a possible metabolite of opioid peptides in rat brain: identification, regional distribution, effects of lesions and formation in depolarized slices.

Using a sensitive radioimmunoassay, the tripeptide Tyr-Gly-Gly (YGG) which corresponds to the N-terminal sequence of opioid peptides was detected in rat brain and identified by HPLC. Its regional distribution paralleled that of (Met5)enkephalin (YGGFM), a marker of enkephalin neurons. Ablation of these neurons in the striato-pallidal pathway by intrastriatal kainate, induced a significant decrease in YGG levels in caudateputamen and globus pallidus (-49%), consistent with the hypothesis that YGG originates from enkephalin neurons. When pallidal slices were incubated under various conditions, YGG was mainly found in the incubation medium indicating a predominantly extracellular localization. Depolarization of these slices by a K+-stimulus elicited a release of YGGFM accompanied by a marked increase in YGG levels. Bestatin and amastatin further enhanced YGG levels, reflecting the participation of aminopeptidases in the metabolism of the tripeptide and its precursor. Captopril, an inhibitor of the angiotensin-converting enzyme (ACE) showed no effect on the recovery of YGGFM and YGG. In contrast, the formation of YGG was completely prevented by Thiorphan (IC50 value = 9 nM) and phosphoramidon, two inhibitors of "enkephalinase" (EC 3.4.24.11; membrane metallo-endopeptidase), thus identifying the latter as the YGG-forming enzyme. The K+-induced increase in YGG + YGGFM levels in medium containing bestatin exceeded by about 60% the amount of YGGFM released from tissues, suggesting that YGG was mainly formed by extracellular hydrolysis of the various opioid fragments of the proenkephalin molecule. In vivo, YGG levels of cerebral regions were also markedly reduced in rats treated with acetorphan, a parenterally active "enkephalinase" inhibitor. All data suggest that YGG levels constitute an index of opioid peptide release.

Animals↗
PubMedDate not supplied

Changes in levels of the tripeptide Tyr-Gly-Gly as an index of enkephalin release in the spinal cord: effects of noxious stimuli and parenterally-active peptidase inhibitors.

The tripeptide Tyr-Gly-Gly (YGG), representing the product of enkephalin hydrolysis by enkephalinase (EC 3.4.24.11), was characterized and its levels measured in spinal cord perfusates of halothane-anaesthetized rats. During noxious pinching of the muzzle, which is known to trigger enkephalin release, YGG levels were enhanced more markedly and for longer than were those of [Met5]enkephalin (YGGFM), in the same samples. By contrast, neither YGG nor YGGFM levels were affected by pinching the tail. Treatment with carbaphethiol, a parenterally-active aminopeptidase inhibitor, markedly increased YGG levels and lengthened the duration of the increase produced by pinching the muzzle. Treatment with acetorphan, a parenterally-active enkephalinase inhibitor, given alone or in combination with carbaphethiol, completely prevented the rise in YGG triggered by noxious stimulation. By contrast, [Met5]enkephalin levels in the perfusates were increased by the combined administration of the two peptidase inhibitors but these levels were not further enhanced by noxious stimulation. Thus, spinal cord YGG appears to be formed under the influence of enkephalinase and to constitute a sensitive index of enkephalin release.

Analgesics↗
PubMedDate not supplied

[Visual evoked potentials in elderly subjects (author's transl)].

Study of visual evoked potentials by contrast stimuli (VEPL) and by luminance stimuli (VEPC) in 28 subjects aged between 65 and 95 years (mean age: 81.8 years). Changes related to aging in regard to VEP involve: an increase of latencies of VEPL affecting the early components and an increase in the maximum amplitude of VEPL. The course of EP as age progresses introduces a difference in topographical organisation with a deterioration of responses in the left occipital regions and a change in potentials recorded at the vertex. Aging would appear to cause more marked inter-individual differences which could have clinical implications by making it possible to demonstrate individual differences in the biological processes of aging.

Aged↗
PubMedDate not supplied

[Artery-nerve conflict. Involvement of the acoustic-facial group].

Six cases of "Conflit Artère-Nerf" concerning acoustico-facial nerves discovered by surgical exploration of cerebello-pontine angle. This conflit is due to an encircling middle cerebellar artery constricting the nerve or by a large Internal Auditory Artery lying upon it. Dissection of the surroundings arachnoidal tracts had given in these cases good results.

Adult↗
PubMedDate not supplied

[Mammary echothermographic comparisons (author's transl)].

This attempt at comparison between the absorption and thermogenesis of breast tumour tissue is currently being continued using a larger group of patients and complemented by measurement of tumour thermogenesis in situ and of the acoustic properties of operative specimens. Such studies define the contributions of thermographic and ultrasonic findings in diagnosis, prognosis and indications for biopsy and treatment, by their integration and combination alongside the data obtained by palpation/inspection and radiological, cytological and histological findings.

Adult↗
PubMedDate not supplied

[Arthrodesis of the sub-occipital spine by screwed occipito-cervical plate. Clinical case and technical notes].

The authors report a new technique in arthrodesis of the sub-occipital spine which has been experienced since 1973 in case of metastases at CI-C2 level. An occipitovertebral metal plate, inverted Y shaped has been realised after anatomical and biomecanical studies. It is adapted to the occipito-vertebral curvature and screwed in the articular processes of C3 and C4 (14 mm screw), and in the pedicles of C2 (32 mm screw). At the upper part, the occiptal ridge offers fixation by 12 and 14 mm Muller's screw. In addition CI is attached to the plate, by a nylon thread. After the report of the first clinical case with a nine month period of follow up technical features of the material as well as practical problems are exposed. Tomograms of the cervical spine as well as bilateral brachial angiography are of paramount value. The latter investigation may reveal anomalies of the vertebral artery that can hinder of forbid the pedicular fixation. Finally the authors discuss the extension of this technique to complexe trauma of the suboccipital column.

Arthrodesis↗