PubMed Health⌕ Search

Biomedical subjects

S Louryan

Publications and source records attributed to S Louryan.

At least 19 recordsLinked to original sources
PubMed2003

Ectopic stapes: a case report with embryologic correlations.

A case report of unilateral congenital stapes misplacement revealed by computed tomography is presented. In addition to this malformation, the malleus was synostosed to the middle ear roof. This kind of stapes ectopia has not been described previously. We have analyzed the malformative pattern in the light of normal and teratologic development of the stapes. In a teratologic model in which retinoic acid is administered to pregnant mice, we have observed an ectopic stapes primordium independent of the otic capsule. We discuss the possible pathogenesis of this abnormality in terms of the genetic events of middle ear development, which can be perturbed by retinoic acid administration.

Adult↗
PubMed2003

Differential expression of S100 calcium-binding proteins in epidermoid cysts, branchial cysts, craniopharyngiomas and cholesteatomas.

AIMS: To investigate whether epidermoid cysts, branchial cysts, craniopharyngiomas and cholesteatomas express S100 proteins differentially by immunohistochemical assaying the presence of S100A1, S100A2, S100A3, S100A4, S100A5, S100A6 and S100B. METHODS AND RESULTS: Immunopositivity/negativity was recorded for each S100 protein in a series of 52 cases consisting of 12 epidermoid cysts, 12 branchial cysts, 15 adamantinomatous craniopharyngiomas and 13 acquired cholesteatomas. Except in the case of the craniopharyngiomas, immunoreactivity was assessed independently in the basal membrane and the basal, the internal and the keratin layers. Our data show that in contrast to S100B, which was rarely expressed, S100A1, S100A2, S100A4 and S100A5 were often present in these four types of epithelial lesions. S100A3 and S100A6 and, to a lesser extent, S100A5 were the most differentially expressed proteins across the different histopathological groups analysed. These three proteins are expressed more often in craniopharyngiomas and cholesteatomas, the two more aggressive types of lesions. CONCLUSIONS: This is the first study to report data on the expression of seven S100 proteins in different histopathological groups of epithelial head and neck lesions, whose precise embryological origins are still a matter of debate. S100 proteins could possibly be used as markers to target this embryonic origin, since our results show that S100A3 and S100A6 (and, to a lesser extent, S100A5) are expressed differentially across these different groups of epithelial lesions.

Adolescent↗
PubMed2002

Computed tomography of a cyclotocephalic neonate.

Cyclotocephaly is a very rare malformative lethal condition which associates otocephaly (extreme hypoplasia of the mandibular arch with agnathia) and cyclopy with proboscis. The head of a cyclotocephalic neonate from our Museum of Anatomy and Embryology was examined using computed tomography (CT). Cutaneous and osseous three-dimensional reformations were performed. Severe bony malformations were observed. A single orbital cavity was surrounded by a cartilaginous proboscis and a median fusion of maxillae, temporal and zygomatic bones. The single orbital cavity contained both paramedial eyeballs (synophthalmia). The external auditory meati and the ear pinnae were also parasagittal. No oral cavity and mandible were observed. Despite the poor conservation state of the brain, lobar holoprosencephaly was suspected. The mesencephalon and pituitary gland were absent. This exercise could lead to optimizing ultrasonographic prenatal diagnosis.

Abnormalities, Severe Teratoid↗
PubMed2002

[Diagnostic imaging of peripheral vertigo].

Clinical imaging investigation of vertigo is actually mainly performed using MRI, which offers a detailed analysis of cochieo-vestibular nerve and labyrinth. Computed tomography is reserved to the analysis of bony structures. Several causes of vertigo are described, e.g. tumours, labyrinthitis, malformations, Ménière's disease, otoscierosis, trauma, cholesteatomas and postoperative changes. The interest of imaging is discussed. The necessity to perform paraclinical tests prior to diagnostic imaging to optimise the choice of imaging is emphasized.

Cochlea↗
PubMed2002

[Heat shock proteins, embryogenesis and evolution].

We present results about immunohistochemical identification of several heat shock proteins (HSP'S) during mouse normal and teratological embryogenesis. Apoptotic cells express very specifically and precociously HSP 110. This fact permits to identify apoptotic cells before apparition of morphologic features of apoptosis, but also to quantify the process of cell death in some teratological models, particularly administration of retinoic acid. HSP 86 is expressed in some cell populations, and particularly permanent in germ cells. Our observations brought us to discuss the potential protective role of HSP on germ cells, and the consequence of their inactivation in the macroevolution process, as well as the role of apoptosis in teratology.

Animals↗
PubMed2000

[From university pedagogy to medical pedagogy: some reflections].

Recent studies have shown that an appropriate pedagogic training, characterized by a high specificity, is necessary for teaching in universities. However, the time when it should be initiated and whether it should be a compulsory or a optional formation are still debated. Furthermore, the specificity of medical training is at the origin of a new expending discipline, medical pedagogy, that must take into account the necessity to provide the students with a basic professional competence. Finally, postgraduate continuous medical education has its own methods that also require a preliminary pedagogic training.

Clinical Competence↗
PubMed1999

The levels of expression of galectin-1, galectin-3, and the Thomsen-Friedenreich antigen and their binding sites decrease as clinical aggressiveness increases in head and neck cancers.

BACKGROUND: The aim of this study was to investigate whether an increase in malignancy level is accompanied by significant modifications of the expression of galectin-1, galectin-3, and Thomsen-Friedenreich antigen (T antigen) as well as the expression of binding sites for these three markers in head and neck squamous cell carcinomas (HNSCCs). METHODS: Immunohistochemical and glycohistochemical staining reactions were carried out with antibodies, labeled lectins, and a custom-made neoglycoprotein on the basis of histologic slides from a retrospective series of 40 normal and 75 HNSCC formalin fixed, paraffin embedded tissues, and were quantitatively described with the aid of computer-assisted microscopy. RESULTS: Whatever the histologic type, the epithelial tissues in HNSCC exhibited very significantly (P < 0.01 to P < 0. 0001) lower amounts of galectin-1, galectin-3, and T antigen and their respective binding sites than their corresponding normal counterparts. The tumors of the larynx differed very significantly (P < 0.0001 to P < 0.000001) from all the other tumor types. A loss of differentiation in the HNSCCs is accompanied first by the loss of expression of galectin-3 and galectin-3-reactive sites and then by that of the T antigen and its binding site(s). The opposite feature was observed when the parameters associated with the TNM classification were taken into account. The negative lymph node HNSCCs could be distinguished (P = 0.02) from the positive lymph node HNSCCs on the basis of a loss of galectin-3 expression. The modifications occurring in the extent of expression of galectin-1 and galectin-1-reactive sites were relatively marginal in comparison with those observed for galectin-3-dependent and T- antigen-dependent staining. CONCLUSIONS: The decrease in the extent of expression of galectin-3 and galectin-3-reactive sites, T antigen and T antigen-binding sites, and, to a lesser extent, galectin-1 and galectin-1-reactive sites correlates significantly with an increasing level of clinically detectable HNSCC aggressiveness.

Adjuvants, Immunologic↗
PubMed1999

Modern imaging of petrous bone malformations: improvement for clinical-embryological correlations.

The rapid perfecting of modern diagnostic imaging during the past decade has provided several new ways to explore ear malformations. Helical computed tomography, three-dimensional (3D) reformations, virtual endoscopy and thin-sliced 3D magnetic resonance imaging constitute the most important recent progress. In parallel, conventional morphologic studies and modern teratologic experimentation give rise to new concepts relative to ear development. The molecular and genetic control of ear morphogenesis is becoming better known, and several malformations can be considered as a consequence of a disruption of genetic or morphogenetic processes. The role of the homeobox genes is particularly important in normal and abnormal development. The field in which radio-embryologic correlations are possible is presently very wide and includes: the association of vestibular defects and lenticulo-stapedial malformations; abnormalities in cochlear coiling; complex ossicular abnormalities; and 'branchial' syndromes. Several experimental models in animals can reproduce this variety of malformations.

Animals↗
PubMed1999

Cranio-facial dysmorphism: experimental study in the mouse, clinical applications.

To obtain a better understanding of mandibulo-facial dysostosis and hemicraniofacial microsomia in man, the authors carried out a histologic and scanning electron microscope study of the facial malformations produced in mouse embryos by retinoic acid and methyl-triazene. The administration of 400 mg/kg 13 cis-retinoic acid (RA) to pregnant C57BL mice on day 9 of gestation produced anomalies of the cephalic extremity in the embryos resembling human mandibulo-facial dysostosis. The 64 embryos collected presented hypoplasia of the branchial arches or the snout in 79% of cases, auricular anomalies in 47% and ophthalmic anomalies in 12.5%. Fourteen NMRI mice on day 10.5 of gestation were treated with 1.5 mg (0.5 mg/kg) methyl-triazene (Methyl). The 126 embryos collected had developed a very high percentage of micromandibles and anomalies of both embryonic ears (94.6% to 100%). Finally, although the facial anomalies produced by retinoic acid resemble the human mandibulo-facial dysostosis syndrome, no correlation was found between hemicraniofacial microsomia and the administration of methyl-triazene.

Abnormalities, Drug-Induced↗
PubMed1998

Dynamic study of the extraembryonic vascular network of the chick embryo by fractal analysis.

Fractal analysis is widely used in many scientific fields, including the study of vascularization. It is a convenient method that defines the complexity of natural structures. The chorioallantoic membrane of the chick embryo is a standard experimental model for the study of vasculogenesis and angiogenesis. The aim of this investigation was to demonstrate that fractal geometry is more appropriate than any other method to describe and analyse the evolution of a vascular network, i.e. the extraembryonar vascular network of the chick embryo. We used an original methodology to evaluate the complexity of this network in the first stages of embryo development (day 3 until 6). We demonstrated an increase of fractal dimension, indicating an increasing complexity of the vascular tree, until an asymptotical value of about 1.70 at day 4. The fractal approach is more accurate than other usual semi-quantitative or quantitative methods evaluating the complexity of a growing vascular tree.

Animals↗
PubMed1998

Effects of irradiation on facial development in mouse embryos.

The purpose of this study was to observe the effects of irradiation on the craniofacial development of NMRI mouse embryos. Two populations of pregnant mice were irradiated with a single dose of 2 Gray on day 8 of gestation for the first population (Po. 1) and on day 9 of gestation for the second population (Po. 2). On gestational days 9 to 17, embryos were submitted to histological and scanning electron microscope examinations. The two populations of embryos presented a high percentage of centro-facial hypoplasia (74.7% for Po. 1 and 75% for Po. 2) which was more pronounced in the latter one. Ocular anomalies were present in 16% of the first population. Cases of anencephaly, cleft palate and anomalies of the central nervous system were found in both populations.

Abnormalities, Radiation-Induced↗
PubMed1998

Effects of irradiation and methyl-triazene on craniofacial development in mouse embryos: a semiautomated morphometric analysis.

OBJECTIVE: The purpose of the present study was a 2D-semiautomated morphometric analysis of craniofacial growth in nuclear magnetic resonance imaged (NMRI) mouse embryos. METHODS: The NMRI mouse embryos were exposed in utero to either a single dose of 2 Gy X-irradiation on day 9 of gestation (113 embryos) or to 1.5 mg methyl-triazene administered orally to their pregnant mothers on gestational day 10.5 (124 embryos). An additional group of 108 embryos was used as controls. Digitized pictures of embryos from gestational days 14 to 17 were taken in lateral right view using a video system. Landmarks were located and digitized for computerized analysis of growth changes in relation to developmental stages of the face. RESULTS: The results revealed that the snout of control embryos lengthens during the developmental period considered. The snout of embryos previously submitted to methyl-triazene displayed micrognathia, and all treated fetuses exhibited macroscopic signs of microcephaly with a reduced mandible. The snouts of irradiated embryos appeared shortened at the 14-day stage and continued to shorten as development proceeded. A shortening of the midface was detected macroscopically in 83% of the cases. CONCLUSION: The results of this morphometric analysis enabled us to trace the developmental progression of the induced dysmorphosis and to assess the differences compared with normal development.

Abnormalities, Drug-Induced↗