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Biomedical subjects

S Louryan

Publications and source records attributed to S Louryan.

At least 55 records · Page 3Linked to original sources
PubMed1996

Comparison between two HNK-1-related antibodies immunoreactivity (HNK-1-anti-leu 7 and anti-HNK-1/N-CAM) during rat cephalogenesis.

The fixation sites of two antibodies, HNK-1-anti-leu 7 and anti- HNK-1/N-CAM, were studied during visceral cephalogenesis in the rat. The labelling patterns of both antibodies were different. Anti-leu 7 staining was restricted to trunk neural crest cells, the peripheral nervous system, myotomes and premuscular cells, the eye rudiment and the olfactory vesicle. On the other hand, anti- HNK-1/N-CAM extended to the otocyst, several epithelia (including tooth germs) and precartilages. Anti-HNK-1/N-CAM staining of somites and cranial nerve ganglia was more precocious than anti-leu 7 labelling. We conclude that both antibodies, despite several common sites labelling, display quite different immunological properties, and that the expression "HNK-1" positive has no absolute significance.

Animals↗
PubMed1995

Ear malformations in the mouse embryo following maternal administration of triazene, with clinical implications.

Triazene administration to 10-day pregnant mice gave rise to severe ear abnormalities, including middle ear ossicle malformations. The head of the malleus and the body of the incus were sometimes absent. In some instances, the stapes appeared dysplastic. The stapedial artery was often quite dilated, as well as other cephalic vessels, but qualitatively normal. Severe inner ear abnormalities were observed, as well as auditory nerve disruption, which was associated with central nervous system lesions. Multiple haematomas were present in the embryonic face, but ear abnormalities occurred even in the absence of local hemorrhages. We postulate a direct effect of the teratogen on the branchial mesenchyme. This model seems to be useful for the comprehension of human middle ear abnormalities, but does not constitute a phenocopy of hemicranial microscomia.

Abnormalities, Drug-Induced↗
PubMed1995

[Contribution and limitations of experimental models to the understanding of certain abnormalities of the face and ear].

The analysis of 4 craniofacial teratological models in the mouse (13-cis-retinoic acid and methyl triazene administration, irradiation, 'far' strain) permits to study the similarities, but also the differences between these models and malformative syndromes in the human. Retinoic acid administration provides a phenocopy of mandibulofacial dysostosis, and irradiation gives rise to a centrofacial dysplasia evoking several holoprosencephalia and Crouzon syndrome. However, triazene administration does not reproduce the hemicraniofacial microsomia.

Abnormalities, Drug-Induced↗
PubMed1995

Nerve growth factor in the developing craniofacial region of the mouse embryo.

Nerve growth factor (NGF), demonstrated by immunohistochemistry, appears during craniofacial development of the mouse in several embryonic tissues. First, NGF is present in the neural and placodic tissues of early embryos. At later stages, NGF staining appears in premuscular and precartilaginous blastemata, as well as in the tooth germs. The presence of NGF in muscular primordia is probably in relation with its putative trophic effect on target tissues. However, cartilaginous expression of NGF supports the view that this molecule could play a role in the regulation of preskeletal differentiation.

Animals↗
PubMed1993

Unilateral duplication of the vestibular aqueduct.

A case of unilateral duplication of the vestibular aqueduct is presented. This very rare abnormality can be explained either by an excessive induction by the rhombencephalon or by an abnormal complete division of the endolymphatic duct into utricular and saccular parts.

Aged↗
PubMed1993

[Development of the auditory ossicles in the human embryo: correlations with data obtained in mice].

The comparison of human middle ear ossicles developmental features with morphological and experimental data obtained in the mouse embryo reveals some points of convergence. The stapes develops mainly form Reichert's cartilage, but the malleus and incus derived partially from the first arch cartilage (Meckel's) and from a Reichert's cartilage-derived blastema parallel to the tubo-tympanic recess. These results permit to validate the mouse model in teratological studies.

Animals↗
PubMed1992

Bi- and three-dimensional CT study of carpal bone motion occurring in lateral deviation.

A computed tomography (CT) study of the right wrists of 15 volunteers and of 5 anatomical preparations in neutral position, radial (15 degrees) and ulnar (30 degrees) deviation enables to tackle the qualitative analysis of carpal bone motion. The CT Scans were analyzed and reconstructed in three dimensions by means of the Philips CAMRA S100 computer program. The results show that the capitate, the metacarpals II and III and, to a lesser extent, the trapezium and the trapezoid are poorly mobile. Our study points to the role of the flexor and extensor carpi ulnaris muscles in the stability of the internal carpus, confirming that the pisiform is a sesamoid bone in the flexor carpi ulnaris tendon. A model of longitudinal functional structure of the carpus during lateral deviation, intermediate between those of Navarro and Taleisnik, is proposed.

Adult↗
PubMed1992

Induced and genetic mouse middle ear ossicular malformations: a model for human malformative ossicular diseases and a tool for clarifying their normal ontogenesis.

Oral administration of 13-cis retinoic acid (RA) to pregnant mice on the 9th gestation day provokes important malformations of the middle ear ossicles, associated with a general kind of craniofacial dysmorphogenesis evoking the human mandibulofacial dysostosis. The malleus, incus and stapes are affected. The malleus exhibits a handle separated from its head and keeping a persistant relationship with the tubotympanic recess. The stapes makes no contact with the otic capsule. The malformation pattern is visible early as shown by the appearance of an abnormally curved Meckel's cartilage at day 12, followed by the development of atypically shaped ossicular anlagen. The mouse "far" (first arch malformation) mutation is responsible for minor ossicular abnormalities which disrupts the normal relationships between the stapes, Reichert's cartilage and stapedial muscle. The administration of RA to pregnant mice and the comparison with a genetically induced malformation (the mutation far) provides some interesting information about the postulated mechanisms of human middle ear dysmorphogenesis, as well as precious data about the features of normal ossicular primordia formation. The comparison of these features with human middle ear abnormalities as revealed by medical imaging sheds light on human malformation patterns and provides a better understanding of normal and abnormal radiologic ossicular aspects.

Abnormalities, Drug-Induced↗
PubMed1992

[Fetal alcoholism syndrome: apropos of a case].

Fetal alcoholic syndrome (F.A.S.) is a well-recognized entity for over 20 years; it associates mental retardation, delayed growth and anomalies of the cranium in children born from alcoholic mothers. The syndrome has been described primarily in young children. By contrast, its evolution is not well known. We report the case of a 15-year old youngster, who exhibited the characteristic features of F.A.S. We also review the data related to the clinical and pathophysiologic aspects of the syndrome.

Adolescent↗
PubMed1992

[The eye and acromegaly: apropos of a case of ptosis].

A 60-year-old woman presents with bilateral ptosis and tearing, predominant on the right and existing since many years. Upper tarsus is much enlarged on the right; lacrymal glands are palpable under the upper lid and seem enlarged as well. CT scan and RMN confirms the hypertrophy of subcutaneous lid tissues, lacrymal glands and ocular muscles. The patient is aware of a progressive change in her physical aspect since years. Medical work-up diagnoses major acromegaly. Discussion about the consequences of acromegaly upon the ocular adnexa.

Acromegaly↗
PubMed1992

[The temporomandibular joint].

With its discordant articular surfaces and complete division in two cavities separated by a disk, the temporomandibular joint appears as a complex anatomical and functional entity. Combined movements involving anteroposterior gliding between the disk and temporal bone in the upper cavity, anteroposterior condyle translation, hinge and rotation movements between the disk and mandibular condyle contribute to the different movements of the jaw. With dental occlusion, the masticatory apparatus therefore includes five functionally coordinated articular compartments. Various impairments of the normal static and dynamic features of the temporomandibular joint may lead to relatively frequent pathological conditions which can be easily diagnosed by modern imaging and arthroscopic methods.

Diagnostic Imaging↗
PubMed1991

Lectin histochemistry in the developing oto-maxillo-facial primordia of the mouse embryo.

The binding sites of several lectins (Con-A, SBA, WGA, PNA, RCA-I, UEA-I, DBA) were studied in the different tissues involved in mouse visceral cephalogenesis. As compared to various other lectins which have only a weak affinity for precartilaginous rudiments, PNA preceded by neuraminidase treatment shows a very strong fixation in the precartilaginous blastemata and their immediate environment. PNA receptors exist also on the enamel epithelium and mesenchymal sac. RCA affinity for blood vessels has also enabled detailed observations on the vascularization of the palatal shelves, particularly in area 3. Various other localizations have been described and correlated with other histochemical data.

Animals↗
PubMed1991

[The value of current imagery techniques in dentistry and stomatology].

Computed tomography, ultrasonography and magnetic resonance imaging are currently used in stomatology and dentistry. These recent imaging modalities have suppressed or reduced classic examinations (by example: conventional tomography and sialography). Efficient, exact and fast, they improve the diagnostic capacities and optimize the choice of the treatments. After some technical considerations, their applications in various stomatology and dentistry problems are evoked.

Diagnostic Imaging↗
PubMed1990

[Magnetic resonance imaging (MRI) of cervico-facial tumors].

Magnetic Resonance Imaging (MRI) gives substantial advantages for the study of tumoral extension in the anatomically complex cervico-facial region. The multiplanar approach permits a better analysis of the anatomical relationships of the tumor, including relationships with the vascular structures, without the need for injecting a contrast medium. The method is able to accurately differentiate tissues and is very sensitive for detecting tumoral tissue. Lesions poorly visible with CT, with poor contrast enhancement or lying in a muscular environment, are well demonstrated. Some difficulties remain for obtaining from patient a complete immobility for a long examination. We think MRI gives a substantial benefit for the diagnostic work-up of cervico-facial tumours, and could be the first imaging technique in this area, particularly if further shortening of the examination time is gained with fast imaging methods and if availability of MRI installations is improved.

Head and Neck Neoplasms↗