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Biomedical subjects

C Laurent

Publications and source records attributed to C Laurent.

At least 289 records · Page 16Linked to original sources
PubMedDate not supplied

Fate of exogenous hyaluronic acid in the middle ear.

The fate of exogenous high-molecular-weight hyaluronic acid applied in the middle ear was studied in rats. Tritium-labelled hyaluronic acid was deposited, and its disappearance through the eustachian tube was followed by analysis of nasopharyngeal secretions. Radioactivity in the secretions reached a peak after three hours and approached zero after 12 hours, indicating that almost all hyaluronic acid had been removed. The middle ears were all empty when opened 24 hours after the deposition of hyaluronic acid. The fate of hyaluronic acid after obstruction of the eustachian tube was followed both with radioactive hyaluronic acid and subsequent autoradiography and by direct analysis of the hyaluronic acid concentration and the hyaluronic acid molecular weight distribution. Radioactive hyaluronic acid was confined to the obstructed middle ear, and no uptake into surrounding tissues could be detected between three hours and four days after the deposition. The amount of hyaluronic acid deposited could be recovered to about the same extent for up to six days. Analysis of the molecular weight distribution of the deposited material indicated only a slow degradation, if any, during the same time period.

Animals↗
PubMedDate not supplied

No evidence for involvement of KCNN3 (hSKCa3) potassium channel gene in familial and isolated cases of schizophrenia.

Several studies have reported in schizophrenia a decrease of age of onset in successive family generations, and this observation is consistent with anticipation. Anticipation is known to result from expansion of CAG repeats in several neurodegenerative disorders. Longer alleles of the KCNN3 gene, which contains a highly polymorphic CAG repeat, and encodes a neuronal small conductance calcium-activated potassium channel, have recently been shown to be over-represented in sporadic cases of schizophrenia. In this report, we tested the hypothesis of an association between longer alleles of CAG repeat in the KCNN3 gene and schizophrenia in 20 families with clinical evidence for anticipation and in 151 unrelated schizophrenic cases. No significant difference in the distributions of allele frequencies was observed between familial cases of schizophrenia and controls, and between unrelated cases and controls. Furthermore, no intergenerational CAG repeat instability was detected in the 20 families. Our results do not support the involvement of the KCNN3 (hSKCa3) gene in the etiology of schizophrenia.

Adult↗
PubMedDate not supplied

Distribution of hyaluronan in the middle and inner ear. A light microscopical study in the rat using a hyaluronan-binding protein as a specific probe.

The histochemical distribution of hyaluronan (hyaluronic acid, HYA) was analyzed in middle and inner ear tissues from rats by use of microwave-aided fixation, a hyaluronan-binding protein and the avidin-biotin/peroxidase staining procedure. In the middle ear HYA was mainly localized in the pars flaccida, the ossicles, the round window membrane and in the endomysium of the middle ear muscles. The subepithelial stroma of the Eustachian tube was strongly HYA-positive. In the inner ear, the spiral ligament of the cochlea and the connective tissue surrounding the nerve fibers emerging from the crista ampullaris stained intensely for HYA. Except for a weak staining of the basilar membrane, the Corti organ was devoid of HYA. The heterogenous distribution of HYA may indicate its specific involvement in middle and inner ear physiology and pathology.

Animals↗
PubMedDate not supplied

Inner ear effects of exogenous hyaluronan in the middle ear of the rat.

1.9% hyaluronan (HA) (mol. wt. 3 x 10(6] was applied repeatedly into the middle ear of rats through a myringotomy. The function and structure of the cochlea was analysed by auditory brainstem recordings (ABR) at 2-31.5 kHz and by light microscopy. The myringotomy significantly impaired the ABR thresholds at frequencies below 8 kHz. Five days after the last application of HA, the ABR thresholds showed minor improvements at 6-8 kHz but were impaired at 12 and 20 kHz, as compared with control levels. One month after the last administration of HA, ABR thresholds were significantly improved as compared with the initial level at 2-6 kHz but normal at all other frequencies. After 3 months, all ABR thresholds had returned to the pre-treatment (normal) level. Five days after the last application of HA, the latencies for almost all frequencies were significantly prolonged for waves II and IV at the ABR threshold. After 3 months all latencies had returned to their pre-treatment (normal) values. Highly concentrated hyaluronan (1.9%) is free from ototoxicity but does have transient functional effects on the inner ear.

Animals↗
PubMedDate not supplied

Staying on track.

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Career Mobility↗
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Aiding adjustment.

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Adaptation, Psychological↗
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[Reverse type of cri du chat disease: 5 p trisomy].

Five patients with a trisomy of the main part of the short arm of a chromosome 5 represented with the clinical picture of the reversetype of the Cri-du-chat syndrome. Its main features are the spurt of gonions, prominent chin, prominent nose root, subnormal skull perimeter, low I.Q. and muscular hypotonia.

Adolescent↗
PubMedDate not supplied

A will to choose.

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Critical Illness↗