Influence of cochlear parameters on the current practice in cochlear implantation : Development of a concept for personalized medicine.

Since the introduction of cochlear implants into clinical routine, the interest in measuring cochlear parameters, particularly the cochlear duct length (CDL) has increased, since these can have an influence on the correct selection of the electrode. On the one hand, coverage of an optimal frequency band is relevant for a good audiological result, and on the other hand, cochlear trauma due to too deep insertion or displacement of the electrode must be avoided. Cochlear implants stimulate the spiral ganglion cells (SGC). The number of SGC and particularly their distribution can also have an influence on the function of a cochlear implant. In addition, the frequency assignment of each electrode contact can play a decisive role in the postoperative success, since the frequency distribution of the human cochlea with varying CDL shows substantial interindividual differences. The aim of this work is to provide an overview of the methods used to determine the cochlear parameters as well as of relevant studies on the CDL, the number and distribution of SGZ, and the frequency assignment of electrode contacts. Based on this, a concept for individualized cochlear implantation will be presented. In summary, this work should help to promote individualized medicine in the field of cochlear implants in the future, in order to overcome current limitations and optimize audiological outcomes.

[Influence of cochlear parameters on the current practice in cochlear implantation : Development of a concept for personalized medicine. German version]. / Einfluss cochleärer Parameter auf die aktuelle Cochleaimplantatversorgung : Entwicklung eines Konzepts für die personalisierte Medizin.

Since the introduction of cochlear implants into clinical routine, the interest in measuring cochlear parameters, particularly the cochlear duct length (CDL) has increased, since these can have an influence on the correct selection of the electrode. On the one hand, coverage of an optimal frequency band is relevant for a good audiological result, and on the other hand, cochlear trauma due to too deep insertion or displacement of the electrode must be avoided. Cochlear implants stimulate the spiral ganglion cells (SGC). The number of SGC and particularly their distribution can also have an influence on the function of a cochlear implant. In addition, the frequency assignment of each electrode contact can play a decisive role in the postoperative success, since the frequency distribution of the human cochlea with varying CDL shows substantial interindividual differences. The aim of this work is to provide an overview of the methods used to determine the cochlear parameters as well as of relevant studies on the CDL, the number and distribution of SGZ, and the frequency assignment of electrode contacts. Based on this, a concept for individualized cochlear implantation will be presented. In summary, this work should help to promote individualized medicine in the field of cochlear implants in the future, in order to overcome current limitations and optimize audiological outcomes.

Neuroanatomy and neurotransmitter regulation of defensive behaviors and related emotions in mammals

1. There is suggestive evidence that the septo-hippocampal system and the amygdala are involved in risk assessment behavior, a response to potential threat possibly related to anxiety. In addition, experimental results have been reported implicating the medial hypothalamus in coordinated escape, while the periaqueductal gray matter (PAG) and the median raphe nucleus serotonergic projection to the hippocampus seem to mediate freezing. The latter defensive behaviors are evoked by distal danger stimuli and may be viewed as manifestations of fear. Finally, there is a sound body of evidence indicating that the PAG commands primitive fight or flight reactions elicited by proximal threat, acute pain or asphyxia. These defense reactions may be related to rage and panic, respectively. In contrast, the lateral septal area and the bed nucleus of the stria terminalis have been shown to exert tonic inhibitory influence on defense. 2. Experimental evidence indicates that gamma-aminobutyric acid (GABA) tonically inhibits defensive behavior in the amygdala, hypothalamus and the PAG, an effect opposed by excitatory amino acids. Among monoamines, serotonin (5-HT) has been suggested to facilitate anxiety in the amygdala while inhibiting panic in the PAG. The role of noradrenaline in defense is less clear, although hypotheses implicating the locus coeruleus in anxiety and panic have been suggested. Among peptides, corticotropin-releasing factor (CRF) acting as a central neurotransmitter is thought to mediate behavioral and physiological effects of acute stress, while opioid peptides have been shown to inhibit defense in the amygdala and in the dorsal PAG. Finally, acetylcholine seems to facilitate defensive behavior in the hypothalamus and the PAG.

Escherichia coli periplasmic chaperone FaeE is a homodimer and the chaperone-K88 subunit complex is a heterotrimer.

The interaction of FaeE, a periplasmic chaperone involved in K88 biosynthesis, and the major fimbrial subunit FaeG was investigated. The genes encoding the two proteins were subcloned together in the expression vector pINIIIA1. Cells expressing the subcloned genes accumulated in their periplasm a complex of FaeE and FaeG. This complex was purified by isoelectric focusing and anion-exchange fast-protein liquid chromatography. SDS-PAGE, native gel electrophoresis, immunoblotting and determination of the N-terminal amino acid sequences and the molar ratio of the N-terminal amino acid residues revealed that the complex is a heterotrimer consisting of two molecules of FaeE and one molecule of FaeG. The periplasmic chaperone FaeE was purified from the periplasm of cells expressing only the subcloned faeE gene. Gel filtration, protein cross-linking analysis and a biophysical approach in which the rotation diffusion coefficient of the purified FaeE was determined led to the conclusion that the native FaeE chaperone is a homodimer.

[Endophthalmia of pseudophakic patients]. / Endophtalmies du pseudophake.

After the era of antibiotics, a real improvement has been stated in the percentage of endophthalmis following cataract surgery which has fallen from 1% between 1950 and 1977, to 0.2-0.3% now. Since 10 lenses have been implanted, the incidence of acute bacterial endophthalmitis due to pathogenic organisms has not increased. But we now encounter many cases of "cold endophthalmitis", with a lowered symptomatology, a delayed onset, and which are due to organisms of low virulence. Their prognosis can be improved by early vitrectomy combined to intraocular antibiotics in the more severe cases, and by using antibiotics of high intraocular penetration in the milder cases. We report fifteen cases of pseudophakic endophthalmitis. The clinical course was acute in one case, sub acute in eleven cases, and chronic in three cases. In the latter fourteen cases a vitrectomy was performed in 60% of the cases. Aqueous and vitreous taps have found cocci gram + in five cases. Visual results are superior to 1/20 in 2/3 of the cases.

[Ocular implantation and exfoliative syndrome]. / Implantation oculaire et syndrome exfoliatif.

Operative difficulties and post operative complications after posterior chamber lens implantation are described in 27 eyes with exfoliation syndrome, 8 simple exfoliation syndromes and 19 capsular glaucoma. 14 eyes were operated on by extracapsular extraction and posterior chamber lens implantation in the capsular bag; 13 eyes had extracapsular cataract implantation combined with trabeculectomy. Operative difficulties were due to bad mydriasis and zonular laxity. There was no zonular dialysis. Post-operative visual acuity was between 20/40 and 20/20 in 70% of the cases. There was nos lens luxation. Intercapsular implantation is possible without great risk. The risk of zonular rupture occurs principally during extracapsular extraction. Implants 4 to 12 times Lighter than a cataract human lens do not seem to be dangerous when there is no peroperative zonular rupture.

[Value of qualitative keratometry for the correction of postoperative astigmatism]. / Valeur de la kératométrie qualitative pour la correction de l'astigmatisme post-opératoire.

The use of a per operative qualitative Keratometer is of interest in prevention of astigmatism in cataract extraction. Our study, which included two groups of forty patients each, demonstrated that the Karickhoff Keratometer can markedly decrease the degree of immediate post-operative astigmatism = gain of 2.38 delta in comparison with the control group and astigmatism less than or equal to 2 in 35% of the cases.

[Galand disk implant and pupillary block]. / Implant disque de Galand et bloc pupillaire.

We have implanted 530 Galand's disc lens in the last 15 months. Stability and self-centering of implant were good when peroperative vitreous pressure was normal and in any case when wound was closed. Pupillary blocks, specific complications of this lens were rare (less than 1%); they can be prevented occurred by simple and adequate protocols.