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Biomedical subjects

J Magnan

Publications and source records attributed to J Magnan.

At least 73 records · Page 4Linked to original sources
PubMed1989

[Diagnostic and therapeutic problems in dissociated forms of Menière's disease].

The authors report the cases of 5 subjects who presented with incapacitating vertigo which was attributed to a dissociated form of Meniere's disease. They stress the difficulty, in these circumstances, in making a precise diagnosis which can only in fact be confirmed with the benefit of a longer follow up. They stress the value of systematically combining frequency analysis with measurement of maximal slow phase velocity during vestibular testing. This allowed better precision in terms of topographical diagnosis. All subjects underwent vestibular neurotomy via the retro-sigmoid approach. The procedure did not alter hearing and compensation occurred within the usual delay. The question therefore arises as to when is the best time to intervene in patients presenting with vertigo of peripheral origin with preserved hearing.

Audiometry↗
PubMed1988

Binding of the non-selective opioid [3H]etorphine in the human fetal central nervous system.

The existence of specific, high-affinity opioid binding sites was demonstrated in 21-week-old human fetuses with the use of tritiated etorphine, a non-selective opioid ligand. Binding capacities measured in the brain, the cerebellum and the spinal cord give values of 2.83, 3.71 and 5.42 pmol/g of tissue. Kd values do not vary from one region to the other and are respectively 0.29, 0.35 and 0.33 nM. These results are compared with the characteristics of opioid binding sites found in adults.

Binding Sites↗
PubMed1988

[3H]U69,593 binding in guinea-pig brain: comparison with [3H]ethylketazocine binding at the kappa-opioid sites.

[3H]U69,593 and [3H]ethylketazocine (mu + delta suppressed) binding was measured in homogenates of guinea-pig brain. Both ligands bind with high affinity to a single class of opioid sites. The relative equilibrium dissociation constant (KD) for [3H]U69,593 is 1.15 nM, while [3H]ethylketazocine has a KD value of 0.33 nM. Their respective maximum binding capacities are 4.49 and 4.48 pmol/g of wet tissue. Various mu-selective, delta-selective, kappa-selective, and nonselective opioids were tested in competition studies against the binding of [3H]U69,593 or [3H]ethylketazocine (in the presence of mu- and delta-blockers) to measure their relative affinity. [D-Ala2, MePhe4,Gly5-ol]enkephalin (mu-selective) has low affinity (600-3000 nM) and [D-Pen2,D-Pen5]enkephalin and [D-Ser2, Leu5, Thr6]enkephalin (delta-selective) have very low affinities (greater than 20,000 nM) at the sites labelled with [3H]U69,593 or [3H]ethylketazocine. On the other hand, unlabelled U69,593, U50,488H, and tifluadom (all three kappa-selective substances) display high affinity (1-5 nM) at those sites. Nonselective opioids, such as bremazocine, levorphanol, and ethylketazocine show similar affinities at the sites labelled with [3H]U69,593 and at the sites labelled with [3H]ethylketazocine. These data indicate that [3H]U69,593 is a selective high-affinity ligand for the same sites that are labelled with [3H]ethylketazocine (in the presence of mu- and delta-blockers) and that these are kappa-sites.

Benzeneacetamides↗
PubMed1987

Localization of kappa opioid receptor binding sites in human forebrain using [3H]U69,593: comparison with [3H]bremazocine.

1. The autoradiographic distribution of kappa opioid receptor binding sites in human brain was examined using two radiolabeled probes, namely [3H]U69,593 and [3H]bremazocine. 2. [3H]U69,593 binding was performed in the absence of blockers for other sites, while [3H]bremazocine binding was investigated in the presence of saturating concentrations of mu and delta blockers to ensure selective labeling of kappa opioid receptors. 3. Our results show that the autoradiographic distribution of [3H]U69,593 and [3H]bremazocine (plus blockers) binding sites is identical, with high densities of sites found in deep cortical layers and claustrum. 4. This indicates that [3H]U69,593 is a highly selective ligand of the kappa opioid receptor type.

Autoradiography↗
PubMed1987

Autoradiographic distribution of multiple classes of opioid receptor binding sites in human forebrain.

Receptor binding parameters and autoradiographic distribution of various opioid receptor sites have been investigated in normal human brain, post-mortem. [3H]DAGO, a highly selective mu ligand, binds to a single class of high affinity (Kd = 1.1 nM), low capacity (Bmax = 160 fmol/mg protein) sites in membrane preparations of frontal cortex. These sites show a ligand selectivity profile that resembles that of the mu opioid receptor. On the other hand, [3H]bremazocine, in presence of saturating concentrations of mu and delta blockers, appears to selectively bind to a single population of kappa opioid sites (Kd = 0.13 nM; Bmax = 93.0 fmol/mg protein) in human frontal cortex. Whole hemisphere in vitro receptor autoradiography reveals that [3H]DAGO-mu, [3H]DSLET-delta and [3H]bremazocine (plus blockers)-kappa binding sites are discretely and differentially distributed in human forebrain. In the cortex, mu sites are concentrated in laminae I and IV, delta sites in laminae I and II while kappa sites are found in deeper layers (laminae V and VI). In subcortical nuclei, high densities of mu and delta sites are seen in the caudate and putamen while high amounts of kappa sites are present in the claustrum and amygdala. The nucleus basalis of Meynert is enriched in all three classes of sites while the globus pallidus only contains moderate densities of kappa sites. Thus, the possible alterations of these various classes of opioid receptors in neurological and psychiatric diseases certainly deserve further investigation.

Aged↗
PubMed1986

Mu opioid receptor binding sites in human brain.

Our experiments focused on the examination of the distribution of mu opioid receptor binding sites in normal human brain using the highly selective ligand [3H]DAGO, in both membrane binding assay and in vitro receptor autoradiography. Mu opioid binding sites are very discretely distributed in human brain with high densities of sites found in the posterior amygdala, caudate, putamen, hypothalamus and certain cortical areas. Moreover the autoradiographic distribution of [3H]DAGO binding sites clearly reveals the discrete lamination (layers I and III-IV) of mu sites in cortical areas.

Autoradiography↗
PubMed1985

[Conditions necessary for a cure of cholesteatomatous chronic otitis].

The authors present a homogeneous series of 750 cholesteatomas treated surgically between 1973 and 1984, 710 cases by a closed technique (94%) and 40 by an open technique. After dealing with the false problem of the choice between open technique and closed technique, the authors attempt to define the conditions required for successful treatment of cholesteatomatous chronic otitis, and on that basis justify their own therapeutic attitude. Excision of the cholesteatoma must be complete and as a single block, from the periphery to the point of origin of the epidermal matrix. Such excision is possible in the majority of cases without damage to the bony canal walls. The risk of residual cholesteatoma fell from 19% in 1978 to 8% in 1984. The prevention of cholesteatoma is based upon our basic knowledge of the disease. It requires avoiding damage to or repair of the osteo-membranous anatomical barrier which separate the two compartments, outer and middle, of the ear. This aim can now be better achieved by the use of tympanic homografts and recent techniques for repair of the bony external auditory canal. Recurrences (13%) are due to the ability of progression of the cholesteatoma but also, and above all, the imperfect surgery. Whilst it was long believed that complete eradication of cholesteatoma was impossible without destruction of part of the architecture of the ear, it is now known to be possible, and even represents one of the best methods for the prevention of recurrences.

Adult↗
PubMed1984

[The jugular foramen, the inferior bulb of the jugular vein and their surgical approach].

Anatomical features of the sigmoid sinus and internal jugular vein and their connections are described. The jugular foramen is really only the opening of a bony canal between occipital and temporal bones, and is equivalent to a connective opening between the occipital vertebra and petrosal bone. The junction between the sigmoid sinus and internal jugular vein has the form and probably also the function of a siphon, but one in which the two arms are at right-angles. The jugular vein sinus has numerous vessels emptying into it, including some; condylar veins and inferior petrosal sinus, that are of high importance: valves are present at their orifices and the jugular sinus contains cords as in the cardiac cavities. The jugular vein sinus certainly plays a physiologic role in venous flow: a rigid-wall canal, the sigmoid sinus is followed by one with flexible, easily collapsible walls: the jugular vein. The latter is submitted to very high negative pressures that have to be compensated for by the sigmoido-jugular siphon in order to maintain cerebral vascular filling. Surgical approach to the jugular vein sinus is complicated by two factors: the facial nerve and hemorrhage. The facial nerve in its bony canal is situated immediately adjacent to the jugular sinus and must be displaced to reach the vein. The sinus is almost always approached for jugular glomus tumors, which are very hemorrhagic lesions. To prevent blood loss, the sigmoid sinus and then the external carotid are linked to the jugular vein.(ABSTRACT TRUNCATED AT 250 WORDS)

Accessory Nerve↗
PubMed1984

[The fronto-supra-ethmoidal approach. Its value in cerebrospinal rhinorrhea].

A supra-ethmoidal approach was used to treat cerebrospinal fluid rhinorrhea secondary to anterior fractures of the base of the skull. After an internal orbital incision, the anterior wall of the frontal sinus is removed and the posterior wall of this sinus trephined in the internal region of its horizontal portion in order to expose the meninges covering the roof of the first ethmoidal space. Dissection is continued within the space towards the anterior extremity of the apophysis of the crista galli against which the fibrous band issuing from the anterior ethmoidal opening is sectioned. The dura mater is then separated from the cribriform plate of the ethmoid up to the jugum sphenoidale posteriorly, while progressively coagulating and sectioning the nerve and connective tissue network attached to the cribriform plate. This freeing of the dura mater exposes the meningeal fistula and allows its liberation from its bony adhesions. A fragment of epicranium removed from the frontal bone is spread between the dura mater and the cribriform plate in order to cover it completely. A drain is then introduced into the nasofrontal canal and the anterior wall of the frontal sinus replaced in position. The advantages of this technique are: the operation is simple, it allows good exposure of the fistula, and since the bony support of the ethmoid is not destroyed the meningeal opening can be easily obstructed.

Cerebrospinal Fluid Rhinorrhea↗
PubMed1984

[Vestibular neurotomy by the posterior retrosinus approach. Technics, results and indications].

A posterior retrosinus approach was used for 50 vestibular neurotomies to treat patients with severe "Ménière's" disease. The pontocerebellar angle is approached by trephination of a 2 cm diameter opening immediately behind the mastoid and lateral sinus. The acoustic-facial nerve bundle lies 55 mm deep to the craniotomy opening. The vestibular nerve is separated from the cochlear and sectioned, the facial nerve not being at risk as it lies much deeper. Results after a minimum follow up of one year showed recovery from vertigo in 96 p. 100 of cases. Deafness, which was unchanged following surgery, did not appear to progress in most cases. Tinnitus was unchanged. Facial nerve lesions were never observed. The operation is a simple one (duration of 90 minutes) and is reliable, and vestibular neurotomy by the pontocerebellar angle approach appears to be most effective currently available method for treating severe cases of "Ménière's" disease. Decompression procedures provide results that are too inconstant, while neurectomy by a suprapetrous approach is a much riskier op eration than that which uses a posterior approach as described above.

Deafness↗
PubMed1983

[Problems of hemostasis and excision technic in glomus jugulare tumors].

An artifice is proposed for controlling bleeding during excision of a glomus jugulare tumor. After ligature of the external carotid or ascending pharyngeal arteries, and of the sigmoid sinus, a balloon catheter is introduced into the internal jugular vein. The balloon is then placed at the level of the jugular vein sinus and distended, preventing bleeding from the inferior petrosal sinus and the condylar emissary veins. The operation is conducted in four stages, their order varying according to the extension of the lesion. The mastoid stage involves freeing of the sigmoid sinus and the third portion of the facial nerve. The cervical stage requires freeing of the VIIth nerve at its entry into the parotid, and of the external carotid and internal jugular arteries, and identification of the IXth, Xth, and XIth nerves. During the third cervicomastoid stage, the facial nerve is completely liberated and pushed upwards, and the jugular apophysis of the occipital resected. The last stage is that of preventive hemostasis and excision. The jugular sinus, external carotid artery and internal jugular vein are ligatured. The internal jugular vein is then catheterized with the balloon catheter, which is distended. The jugular vein sinus is opened, the afferent vein orifices clogged, and the lesion excised.

Catheterization↗