Search PubMed⌕ Search

Biomedical subjects

S Louryan

Publications and source records attributed to S Louryan.

At least 37 records · Page 2Linked to original sources
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↗
PubMed1998

[The role of apoptosis during craniofacial development: concepts and importance in pathology].

Apoptosis is an essential common final pathway in numerous pathological conditions such as malignant tumors, HIV-related CD4 lymphocytes degeneration, neurodegenerative disorders, and in programmed cell death events during normal embryogenesis. Some teratogenic substances for man and laboratory mammals induce an increase of the apoptotic phenomenon, responsible for the occurrence of some precise cranio-maxillo-facial malformations. The study of cell death during normal or teratogenic embryonic development allows to analyse the cellular mechanisms implied in the control of the apoptotic phenomenon, together with its dysregulation ending in pathological processes. We review the cell death phenomenon during cephalogenesis, both during normal embryogenesis, or in teratogenic conditions known to induce cranio-maxillo-facial malformations.

Abnormalities, Drug-Induced↗
PubMed1998

Yolk sac tumor of the ear in a child.

OBJECTIVE: This study aimed to describe the clinical, histopathologic, and immunohistochemical findings of the second case of an endodermal sinus tumor of the ear. STUDY DESIGN: This clinical study is a retrospective case report combined with a literature review. SETTING: The patient was treated at the University Erasmus Hospital. INTERVENTION: Diagnosis was confirmed by computed tomographic scan and histologic analysis. The treatment was surgical. RESULTS: The patient underwent surgical treatment, and a locoregional relapse developed. The clinical evolution was in accordance with previous reports of extragonadal endodermal sinus tumor sites. The family refused chemotherapy, and the patient died 3 months after admission. CONCLUSIONS: An endodermal sinus tumor is a malignant germ cell tumor that usually involves the gonadal tissue. Extragonadal sites are rare, and different hypotheses have been evoked to explain these locations. Treatment options include surgical removal and chemotherapy. This is the second case of an endodermal sinus tumor of the ear.

Child, Preschool↗
PubMed1997

Anomalies of fetal development in GK rats.

Fetal development was investigated in Goto-Kakizaki (GK) rats. Between days 15 and 20 after identification of a positive sperm plug, the GK rats gained less weight than control animals. The number of conceptuses in each litter was not significantly different in control and GK rats. The incidence of abortive fetal development, however, averaged 39.7% +/- 9.1% in GK rats, compared with only 5.6% +/- 0.2% in control animals. The placental weight in living fetuses was slightly lower in GK rats than control rats. The crown-rump length was identical in the fetuses of control and diabetic mothers. The number of ossification points in the lumbosacral spine, pelvic girdle and anterior and posterior limbs was significantly lower in fetuses of GK rats than control animals. These anomalies could not be blamed on a lower plasma insulin concentration in GK than control animals, whether before or during (days 15-20) pregnancy. Moreover, in both control and GK rats, the insulinogenic index was raised during pregnancy. These findings indicate that GK rats represent a new model for the study of diabetes-related fetal anomalies, their pathogenesis and prevention.

Animals↗
PubMed1997

Myxomatous odontogenic tumor of the maxilla. An unusual case with squamous and mucoproducing epithelial component.

A tumor attached to the amelo-cemental junction of a third molar impacted in the maxillary tuberosity, consisted histologically of a myxomatous stroma, in which multicystic cavities lined by a columnar epithelium and mucoproducing cells, together with an aggressive squamous epithelial component were present. Although the diagnosis of polyp of the maxillary sinus cannot be excluded, this lesion most likely constitutes an unusual presentation for an odontogenic myxoma of the maxilla, in which an aggressive squamous epithelial component is present, along with a mucosecreting glandular component.

Adult↗